2003_Prototypic Realisation of Millimetre Wave Radar Imaging

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国外民粹主义研究前沿精品

国外民粹主义研究前沿周凡尽管列宁在1912年所写的《中国的民主主义和民粹主义》一文中把孙中山的民主革命纲领称作民粹主义的纲领并把孙中山称作“中国的民粹主义者”，[1]尽管有学者断言毛泽东曾染上民粹主义色彩甚至认为中国的“文化大革命”就是民粹主义性质的政治运动，[2]但是，民粹主义无论作为概念术语、作为社会思潮、作为政治运动抑或作为一种意识形态，最初并不起源于中国。

俄国十月革命一声炮响，给中国送来了马列主义，同时，也让中国人了解了民粹主义——中国人最早就是通过马列主义知道民粹主义这个概念的。

世界最早的民粹运动发生在俄国，而且，不论是马克思、恩格斯还是列宁，都一无例外地遭遇过、思考过、探讨过、回应过俄国民粹主义(Narodnichestvo)问题。

在19世纪晚期的俄国，马克思主义是在俄国民粹派和其他民粹主义运动不能说服民众加入他们的事业之后才获得长足发展的，因此，就俄国当时的情况而论，马克思主义在俄国的胜利在某种意义上也就意味着俄国民粹主义的失败;但是，俄国民粹主义的失败并不等于民粹主义的销声匿迹。

自俄国在19世纪六、七十年代出现轰轰烈烈的民粹主义运动以来，作为现代社会的一种独特现象，民粹主义在世界范围内从来没有彻底断绝过、消失过。

一如保罗•塔格特所言，“民粹主义是间歇性的插曲，它不时强劲地迸发并带来激进政治变革的潜能，遽然之间，它又消退殆尽;然而，民粹主义并非全无效验，在其极盛时，它总会使政治的内容和基调发生结构性变化，哪里有代表民意的政治，哪里就有作为极具潜力的运动和政治观点的民粹主义”。

[3] 就在俄国民粹主义日渐衰竭并濒于消亡之际，美国在19世纪晚期爆发了著名的“人民党(Populist Party)”运动。

二十世纪三、四十年代，法西斯主义利用民粹主义的动员方式登上了欧洲的政治舞台，而随着纳粹主义的覆灭和冷战时代的到来，民粹主义在1950-1960年代成为拉丁美洲政治的主流。

二十世纪80年代以来，民粹主义在国际范围内此伏彼起、掀起了一次又一次的高潮，特别是20世纪90年代以来，民粹主义在欧洲持续升温，所谓“新民粹主义(Neo-Populism)”声浪日壮，欧洲各国中右政党和极右势力纷纷抬头。

2003美赛B题M奖 Optimization of Stereotactic Radiosurgery Treatment Planning

Optimization of Stereotactic RadiosurgeryTreatment PlanningIntroductionGamma knife, which uses stereotactic radiosurgery, is extensively used to treat a wide range of cancers. This therapy satisfies our needs by destroying locus as a result of enough radiation, while avoiding unnecessary damage to the surrounding tissue and organs. In the field of medicine, we can get optimal results if the dosage inside average tumor reaches above 50% .Our model, during the whole treating course, is considered as a bulk composed of a group of isodose curves, which have the same center, inside the tumor. Guaranteeing the safety of surrounding tissues, we only take into account the volume relationship between the tumor and what 50% isodose curve encompasses. Through discrete digital calculating, we can decide optimal shots, locations, beam channels’ diameters and all these parameters make 50% isodose curve coincide with tumor’s contour. We also analyzed more difficult situations (see Figure 0). The small ball stands for the critical tissue, which must be outside the curve surface enclosed by a certain dosage curve.We designed a computer program to deal with varieties of tumors’ shapes, which can be produced through continuous curve surface’s equation or discrete data. Applying geometrical and physical laws, this treating course can be simulated as a sphere-packing problem. Tumor’s external is imagined to be firm and mustn’t be protruded by 50% isodose curve. When the requests of volume, dosage and gradient are met, packing will stop.Analysis of the ProblemAccording to clinic request, an optimal therapy planning must conform to rules as follows: z A “conformity” goal:High-dosage area should approximately coincide with thetumor’s volume.z A “homogeneity” goal: Dosage distribution should be homogeneous as much as possible, that is, energy gradient inside the volume of tumor must be small.z“Decrease” goals:Dosage outside tumor must be decreased to minimum.z Gradient goals: Ensure low dosage gradient inside tumor and high enough gradient on the edge.z Safety goals: If there’re significant critical organs, we must see to it that dosage on them is lower than the safe value.Therefore, we must consider how to protect surrounding normal tissues, as well as how to effectively destroy locus area. Furthermore, we must prevent critical tissues from being damaged by radiations. So proper choice of shot-related parameters, including number of isocenters, locations and beam channels’ diameters has become very important, Only in this way can we get optimal dosage curve surface in line with tumor surface.Considering factors above, our algorithm should solve these problems well.z Damage will be done to normal brain cells each time, so we should guarantee that shots are as few as possible.z In order to form the largest volume covered, we need more radiation and beam channels of longer diameters.z In order to lower the dosage gradient of target volume, we need beam channels of longer diameters.z In order to bring down the damage done to critical organs, we can’t produce shots near them. Meanwhile, choice of small-size beam channels is also essential.The most difficult problem we met is that there’s not a perfect therapeutic plan, and many requirements are even contradicted conflict with each other, especially about shots and target volume. Target volume is the function of shots. The more shots are, the bigger the target volume is. But our model requires that shots are as few as possible and target volume is as big as possible.Assumptions and Hypothesisz Tumor’s position, contour can be precisely detected.z Critical organs’ position, contour and volume can be precisely detected.z We assume the thickness of tissues involved can be neglected.z Minimum effective therapy dosage is 50% of maximum, that is, volumes which receive dosage less than 50%, with exception of critical organs, will not be damaged.z Tolerance dose of critical organs is lower than that of normal tissues, so we can just give it 30% of maximum dosage.z Tolerance dose of different critical organs is identical.z Distribution of 201 radiation sources is homogeneous on the helmet, so these 201 beams intersect at the isocenter and form a sphere.z Radiating time is always the same, and the maximum dosage, too.z Bad cells inside tumor are also distributed homogeneously so therapeutic effect of identicaldosage is the same.z Media are also homogeneous outside tumor.z There’s no normal tissue inside tumors, and they are all tumor cells.Table 1．Symbols used.Structure of radioactive sourceGamma knife is composed of 201colbat-60 distributed on a semi-sphere.Each one of them has individuallongitude and altitude. They form 201radioactive cones and there is a shot oflargest intensity at the peak. Moredetails acquired in Figure 1.Model of Dosage CalculationIdeal model dosage calculation is to employ Monte Carlo’s method applicable to radiating field of any shape, energy distribution of any radiation, inhomogeneity of any medium which we Symbol Unit Definition UGy total dosage value of a point U NGy overall tolerable dosage of a normal tissue U CGy overall tolerable dosage of an critical tissue s mm beam channel’s diameterF 2 dimensionless modification factorTMR dimensionless tissue ‘s maximum ratioOAR dimensionless off-axis ratioC dimensionless constant which changes radiation exposure time into dosageOF dimensionless output factorω dimensionless power amount distributed to a shotη dimensionless Packing ratioλ mm side length of volume elementN 1 number of radioactive sourcesN T 1 V olume elements’ number contained in a shot areaN D 1 V olume elements’ number contained in half-dosage volumeM 1 number of shotscan calculate dosage distribution via simulatingphysical course of interaction between photon andmedia. In order to be suitable for clinic application,we assume that the media are homogeneous forpractical use. In this way the energy space’sdiffusion mode formed by the main interactionbetween radiation and media (that is, there’s no edgeeffect), so it is practicable to the calculation of anypoint in the media. Based on this case, we use Rapidsearching algorithm in combination with MonteCarlo’s method to calculate dosage.Let’s have a look at Figure 2, O is the focus ofradiation, which is also the semi-spherical maskingbulk’s center. φis single source S ’’ altitude on the masking bulk, β is the longitude. OS is axis of radiating field with the definite length of A . The vertical line from P to OS interlaces OS at P’, Q is the interlacing point of OS and surface. S’ is the vertical interlacing point from S to XOZ plane. Thus the absorption dosage of any point P(X, Y, Z) is:()()()()2D ,,,,,p OF TMR p OAR p p X Y Z C U s U s d U r s d F =××××In this formula, r p is the distance from P to axis; d p is the distance from the projection of P to the radiating field’s axis to surface. According to Figure 2, we can calculate:p r PP ′===()2 ()cos cos cos sin sin p d A SSD OP A SSD X Z Y φβφβφ′=−−=−−++ ()3 We can get the value of TMR and OAR at point P by referring to scientific tables, ( we give C the value 1 because of the same radiating time) and then the absorption dosage of this point under the condition of single source and single shot can be calculated.When many sources are radiating, the dosage we get is total amount when all sources radiate at the same time. According to formula （1）, we know that the total dosage at point P is:()()()()2j 1X,Y,Z ,,,j Nj OF TMR j OAR j j D C U s U s d U r s d F ==××××∑ ()41,...,,100j N N =＝, j is the number of radiating sources.When the number of shots is M , the total dosage at point P is:()()1,,,,M i ii U X Y Z D X Y Z ω==∑ ()5()11,...,,i i M ω=is the power weight distributed to the shot which ranks i in sequence.Considering the whole 3D space, we used Rapid Searching Algorithm, and its steps are as follows:1. We cut the 3D space whose center is the isocenter, and then we get many small cubicvolume elements whose side length is λ. Suppose it can be divided into a b c ××elements.2. According to the request, we can work out the value of λ. If λ meets error requirement,we can substitute dosage of the center for that of other points in this volume element.3. With formula （5）and step λ, work out the dosage value of every volume element. Tocalculate a b c ××times is needed. In this way, we can get the distribution of spacialdosage. Changing the value of λ, we will get dosage of different accuracy.Suppose λ＝0.5mm, dosage distribution section’s illustration when we give it 1 shot and that when we give 2 are as follows, and we can see 9 isodose curves (from 10% to 90%). In Figure 4.b , distance between two shots’ centers is 12mm.Judgment of Dosage Gradient in Shot AreasWe can obtain from both practical analysis and computer-simulating results that gamma radiations are focused through rotation of 201 cones and then form a high-dosage area encompasses the focus. The area’s dosage intensity gradually weakens from focus to edges in the way of isocenter circle and the weakening sharpness is related to size of the beam channel. In this way, we can get the half-dosage curve’s width and sharpness degree of each beam channel. More details can be obtained from Table 2.Table 2: (Unit: mm)Half-dosage curve’s width and Sharpness degreeBeam channel’s radius Half-dosage curve’s width Sharpness degree4 6.1 3.68 11.5 7.514 19.5 11.818 24.7 12.2We conclude from Table 2 that relationship between sharpness degree and beam channel’s radius is positive proportion. The smaller size a beam channel has, the more concentrated the dosage is and the quicker the edge dosage weakens, that is, the higher gradient shot area has; on the contrary, the lower gradient in the shot area is. Thereby, beam channels of bigger size are better.Damage to Normal TissuesWe can attain overall absorption dosage at any point such as P(X, Y, Z) from the foregoing:()()1,,,,M i i i U X Y Z D X Y Z ω==∑According to assumptions, we can find a point (),,NORMAL P X Y Z within normal tumor, and then know whether normal tissues are damaged. Of course, we must adopt different paces in different conditions.1. If ()N ,,U X Y Z U ≥, we need to adjust shots, locations and sizes of beam channels.2. If ()N ,,U X Y Z U ≤, that’s OK.Our goal is to make damage to outer tissues slightest, that is, tissues near the contour must be damaged slightest. So highest dosage gradient near the contour must be guaranteed. We indicate it in discrete method:()(){}max ,,,,U X Y Z U X Y Z λλλ−＋＋＋ ()6 Note that (),,X Y Z is coordinate of a point on the contour. Damage to Critical TissuesCritical tissues can be precisely detected according to assumptions, that is, (),,CRITICAL P X Y Z within critical tissues is definite. First, we must guarantee that the maximum value of damage to critical tissues must be smaller than U c . Second, we make the maximum value smallest. Namely, with regard to ()(),,,,CRITICAL P X Y Z P X Y Z ∈ :(){}()min max ,,CRITICAL U X Y Z ()7 (){}C max ,,U X Y Z U ≤ ()8Calculation of V olume-packing RatioAfter cutting the whole space into volume elements, total volume surrounded by any contour can be measured by number of volume elements in it. We can also say that total volume is equal to product of λ3 and number of volume elements. When we know the contour, computer will search in 3D space with the step of λ and work out N T . Likewise, we can work out N D . So packing-ratio η can be represented as below:33100%100%D D T TN N N N ληλ×=×=×× ()9Number of Shots and Original Value of ShotsAs far as an isocenter is concerned, the original value of s is undoubtedly given a value as big as possible. And its original position is any point which satisfies the conditions below:1. Half-dosage curve will not exceed the tumor;2. 30% isodose curve will not cover critical tissues.When there’s no condition-satisfied point, decrease s and then search. Suppose the number of isocenters for a certain tumor []1,15M ∈. When diameter of the beam channel s and position of itchanges, M‘s value constantly changes. Suppose isocenters is ()i ,,F P X Y Z , and then:{}4,8,14,18s ∈， ()[]i F ,,1,P X Y Z Shot Area i M ∈∈，So we can define M using formula below:(),,,M f X Y Z s = ()10 Namely, shots are determined by isocenters’ locations and beam channels’ diameters.Model DesignTaking into account dosage gradient, damage to normal tissues, damage to critical tissues and packing ratio, we get the following discrete model to ascertain reasonable number of shots, locations and beam channel’s diameters.()()()()()(){}min ,,,90%,,,,.,,,,,,481418.NORMAL N CRITICAL C M f X Y Z s U X Y Z U U X Y Z U s t P X Y Z Shot AreaP X Y Z Normal TissueP X Y Z Critical Tissue s η′′′=⎧>⎪′′′′′′<⎪⎪′′′′′′′′′<⎪⎪′′′∈⎨⎪′′′′′′∈⎪⎪′′′′′′′′′∈⎪⎪∈⎩，，，Steps implemented by computer are as follows:1. add a isocenter (),,P X Y Z ′′′；2. move any isocenters (),,P X Y Z ′′′ by step λ，making s.t met: if max{η}<90%, thengo to step1；3. move any isocenters (),,P X Y Z ′′′，till max{η};Algorithm ends, present plan is optimal.．Model ModificationFor we have cut the whole 3D space into small volumes, calculation amount is very tremendous especially when λ is small. Considering these factors, we can properly simplify the running course of our program. Accordingly, running time will reduce on basis of guaranteeing accuracy. These aspects below may be what we should pay attention to:● Diminish the value range of M, based on tumor’s contour.● We also diminish the value range of (),,P X Y Z ′′′ according to tumor contour, criticaltissues’ contour, corresponding sharpness degree and half-dosage curve’s width. The final changed range is S 1.● Choose some points on contour’s curve, and these points’ assembly will take the place ofcontour curve.S 2 stands for the assembly of points in normal tissues; S 3 stands for assembly of points in critical tissues, if there’s no critical tissue, S 3 is empty.The original model will be altered into the following formula:()()()()()(){}123min ,,,90%,,,,.,,,,,,481418.NORMAL N CRITICAL C M f X Y Z s U X Y Z U U X Y Z U s t P X Y Z S P X Y Z S P X Y Z S s η′′′=⎧>⎪′′′′′′<⎪⎪′′′′′′′′′<⎪⎪′′′∈⎨⎪′′′′′′∈⎪⎪′′′′′′′′′∈⎪⎪∈⎩，，，Model ApplicationWe supposed an irregular complicated tumor after outputting discrete data in MATLAB. And there’s a critical tissue near the concave place. You can get the general situation from Figure 0. λ=0.5mm , the size of containing box is 100×100×100. Consequently, we can work out the number of volume elements-----64807.Table 3. Illustration of optimizing processshots V olume elements’ numbercontained in half-dosage volume Packing ratio1 42493 65.6%2 52556 81.1%3 57030 88.0%4 5968692.1%We can see from this table that packing-ratio will increase more slowly when shots’ number increases. When shots’ number reaches 5, the packing ratio will increase quite slightly and the computer program will neglect it automatically. Finally we got 4 isocenters. More details are in Table 4.Table 4. Isocenters1 2 3 4 Isocenter’s coordinate P i(X,Y,Z)(-6，11，-2)(0，-12，0) (5，-4，1) (5，3，1)Beam channel’s diameter S i(mm)14 8 4 4In order to justify validity of the model, we pick up 3 sections and they are z=0, x=5, y=5 separately. The charts of them are as follows:This chart shows: 50% isodose curve doesn’t exceed target volume and 30% isodose curvedoes not cover critical tissues. Moreover, it also tells us the distribution regularity of isodose curves. Inside the tumor, they are dense; while outside the tumor, they gradually become sparser, rapider in weakening, and larger in gradient. So selection of isocenters is reasonable and valid.Error AnalysisSelection of the initial point in this model constitutes a problem. When the number of isocenters increases, this model chooses any random point in line with conditions within tumor volume as the initial one. Therefore, this model is random to some extent, which leads to incomplete results as a result of improper choice of the initial point. We solved this problem by calculating several times so as to get the best solution.Sensitivity AnalysisThis model is not designed for a shape-designated tumor, and it considers tumors of anyshape even shapes simulated from discrete data. Consequently, it is applicable to tumors of any shape.To determine our model’s stability, we choose different values of U C and U N， It doesn’thinder our attainment of the best solution, although the best solution would be different if we choose different maximum dosage.At the same time, we also consider different OF，F2 and C, and then get corresponding bestTeam # 163 Page 11 of 11 solution. In practical use, the model can be adjusted to application, by given different factors.Strengths and WeaknessesThis model can arrive at above 90% or any given proportion’s therapeutic area for tumors of any shape, but it won’t damage normal cells, furthermore, it protects surrounding critical cells. It implement realizes good therapeutic effect on the basis of adequate safety.The shape of tumor can be given by any curve surface’s equation, or by discrete data similar to CT images in clinic practice, and tumor’s contour can be very complex. In this way, it has extensive range of application. In the course of simulating sphere-packing in the whole area, to calculate the accurate shots, position and beam channels’ diameter makes therapeutic error smaller, suitable for manipulation in practical treatment.We think that there’s no perfect plan for a practice, and the best plan got from model is based on contemplations of the balance between therapeutic area and shots, and it is, to some extent, affected by random original points, which is the most serious flaw.To different contours and critical tissues, we need to change the value of λ according to the error allowed, which will inevitably influence the executive results.Time complexity of this algorithm is not large, but large quantities of time are still needed. Therefore, selection of original points and moving of shots also require improving.ConclusionOur model has solved the problem of shots, dosage gradient and packing- ratio’s calculation, so it’s suitable for clinic application. However, some other factors need to be considered in further modifications.Referencesz Clinic application of body gamma knife /html/4-4/4-4-16.htm.z Bao Shanglian, Guo Jingxin. Gamma knife Dosage's Monte Carlo Calculation. [1999].z Elekta Edition. User's manual of Leksell Gamma Unit.[April 1992].z Yan Y, Shu H, Bao X, etal. Clinical Treatment Planning Optimization by Powell's Method for Gamma Unit Treatment System. Int J Radiate Oncol Biol Phy, 1997, 39(1): 247~254.z Morrill S M, Lane R G, Jacobson G, et al. Treatment Planning Optimization Using Constrained Simulated Annealing. Phys Med Biol, 1991, 36: 1341~1361.z Zhang Zhixing. Matlab Program Designing and Applying. 2001.。

身体部署(简体)2003

身体现象学及其阴影哲学如何谈论身体？就身体经验所引生的种种惑觉（sensation）和感受（affection）而言，如果不限制一般心理学的理论思维中，而强调感觉本身做为事件与不透明状态来看，身体经验经常具有不受拘束、无法综合、流动不居的特质。

诚如李欧塔（J-F. Lyotard）借用康德（I. Kant）第三批判谈论「祟高」（sublime）的问题时指出：崇高经验的特殊性之一，来自于它无法在感觉与感受上定位，它是一种感觉经验，相对于可说、可论述的日常经验来说，崇高是一种不可说、无可名状的经验状态。

李欧塔特别强调，康德在讨论崇高感受时，给予这种特殊感受状态以先天（a priori）地位，或者，我们可以称之某种域外经验。

其实，我们不难在这方面找到发人深省的阐释。

我们注意到的是布朗修（M. Blanchot）《黑暗托马》（Thomasl Obscur）的第一章。

游着泳的主角不知不觉游出了习惯的海城，游到了陌生、无规则、视线不明与巨浪升涌的海域，使得他连游泳的习惯都无法运作，接近死亡，主体隐遁，意识蒙昧，几乎完全与激烈涌动、冲击着身体的海水消泯了界限。

主角无法说明这种感觉状态，因为，所有的感觉在此时都处于不受拘东、无法综合、流变不居的碎片中。

李欧塔阅读下的康德，让这种无可名状的经验成为崇高审美判断得以发生的条件，并被主张在此无法想象、无法透过知性理解的破碎身体经验中，却仍具有一种力量、一种强度，让主体停留在一个无法形成「自我」（Soi）的判断机能里面，在这个机能的条件底部，说明康德的主体性哲学里面，仍有一个阴影式的主题状态，也可以说是感觉流变的结点。

由于这个模糊结点是崇高审美判断的核心经验，如果我们强调崇高审美判断的确存在，这种判断无法以目的性来说明，其判断对像又超越了主体的想象与知性范围，无法藉由理性来限定，那么，这种特异的流变体验便成为主体性哲学、意识哲学范围之外的一个存有状态，换句话说，这种体验连「我思考」（Ich denke）这个主体性哲学最初步的门坎都跨越不了，而处于单纯的摄受（apprehension）状态中，此摄受之中虽蕴藏有诸多经验杂多，但这些杂多却处于彼此卫突不合的非思状态，所以，它谈不上能在想象中进行任何在生、复制（reproduction），当然也就谈不上跨入一般判断力的认取、确认（recognition）阶股，也就是说，这类特异地生体经验在根本上即与知性、知识状态遥遥相对，成为无法化为知识生产对象的异样他者。

Proceedings of the 2003 Winter Simulation Conference

Proceedings of the 2003 Winter Simulation ConferenceS. Chick, P. J. Sánchez, D. Ferrin, and D. J. Morrice, eds.ITERATIVE OPTIMIZATION AND SIMULATION OFBARGE TRAFFIC ON AN INLAND WATERWAYAmy BushW. E. BilesG. W. DePuyDepartment of Industrial EngineeringUniversity of LouisvilleLouisville, KY 40292, U.S.A.ABSTRACTThis paper describes an iterative technique between opti-mization and simulation models used to determine solu-tions to optimization problems and ensure that the solu-tions are feasible for real world operations (in terms of a simulation model). The technique allows for the devel-opment of separate optimization and simulation models with varying levels of detail in each model. The results and parameters of the optimization model are used as input to the simulation model. The performance measures from the simulation output are compared to acceptable levels. These performance measures are then used to modify the optimization model if the simulation results are not accept-able. This iterative approach continues until an acceptable solution is reached. This iterative technique is applied to barge traffic on an inland waterway as an example. Linear programming is used as the optimization technique for the example while a simulation model is developed using Arena software.1 INTRODUCTION1.1 Relevance of Iterative TechniqueSimulation and optimization techniques are commonly ap-plied in tandem to study many types of real world prob-lems. Both simulation and optimization are applied to the same problem mainly for two reasons. First, it allows an analyst to simulate a specific system and then determine the optimal value for some parameter within the problem through the application of an optimization technique. An example of this is the OptQuest optimizer within Arena. It allows a specific simulated system to be optimized to de-termine the optimal values for a set of specified parame-ters. Various other techniques can be used to optimize specific parameters within a simulation model. Extensive examples and methodologies of the optimization of simula-tion models are available. Fu (2000), Swisher et al. (2000), Glover (1999), and Azadivar (1999) all presented various techniques at previous Winter Simulation Conferences. Secondly, simulation is often applied to the results of an optimization problem in order to check the validity of the model and/or the results. The results of the optimization model are used as inputs to the simulation model1.2 Separate Optimization andSimulation ModelsThis paper suggests developing separate optimization and simulation models, allowing for different levels of detail to be included in each model. An iterative procedure between the simulation and optimization model is suggested in or-der to guarantee a near-optimal solution is reached that is also feasible based on the simulation model constructs. Jaccard et al. (2003) and Brekke and Moxnes (2001) apply separate optimization and simulation models in order to compare the results. The results in both cases indicate that both types of modeling have a positive impact on decision making but for different reasons. The different techniques are compliments to each other, not substitutes. A related iterative technique was presented by Morito et al. (1999) in which optimization constraints were added to the model based on simulation results.Applying an optimization technique alone to a real world situation leads to valuable information about the sys-tem. Obviously, the relevance of the results depends on the quality of the model. Optimization is useful for long term strategic planning. The optimization technique ap-plied here for illustrative purposes is linear programming, but other techniques are equally applicable.The linear program is not useful for day-to-day opera-tional planning. For example, the LP may yield a result that 150 barges should be allocated from fleet 1 to elevator 2 over a planning horizon of one month. This informationdoes not aid decision makers in making day-to-day deci-sions about barge routing.The application of optimization to such a large prob-lem can lead to difficulty in interpreting and validating re-sults. The first issue is whether or not the solution deter-mined by the optimization is a ‘realistic’ feasible solution. A realistic feasible solution refers to a solution that is not only feasible for the optimization model but also feasible for the real system. A realistic feasible solution is feasible for the optimization model, and the parameters of the op-timization are acceptable in the simulation model. In cer-tain situations it is not possible to include all the con-straints and operating procedures for a real system in an optimization model. In these situations simulation can be a useful tool for incorporating all the required procedures and constraints of the real system.The application of a simulation model will allow cer-tain real world system requirements to be included in the analysis that are not considered in the optimization. Con-straints and procedures may not be included in the optimi-zation because it is not possible to include them in an op-timization model or because they are not relevant to long-term strategic planning. 1.3 Application to Modelinga Barge SystemThis paper will apply the proposed iterative approach to simulation and optimization to a specific real world prob-lem. The application is that of barge traffic in the lower Mississippi River region. Barges enter this area of the river from the Gulf of Mexico as well as from various river inlets. Figure 1 below shows a simplified example of a river system.Unload Location Fleet Location Load Location Fleet with Clean and RepairFigure 1: Simplified Example of a River SystemThe basic traffic flow begins with barges being brought into the system via tows. The entrances and exits to the sys-tem are illustrated by the arrows in Figure 1. A tow consists of a group a barges being moved by a towboat. Loadedbarges have specific locations at which they are to unload their cargo. Tows are initially dropped at a fleet location (a location for organizing incoming and outgoing tows) to re-group and be sent to their assigned unload destination. Tows can be powered by different types of boats of varying sizes, towing capacities, and operating costs.Barges are delivered to their unload location and then sent to various fleet locations for cleaning and repair ac-tivities as required. Following cleaning and repair, barges are redistributed for loading. Loaded barges are sent to fleet locations to be organized into tows to be taken out of the system in the appropriate direction.The barge transport system is studied to determine barge routings through the system in order to minimize the cost of barge movement. The routings are based on unload location and exit direction of the barges. These routings are critical as barges can take various paths through the system to reach their destination. This means determining locations for barges to be redistributed and organized into tows as well as locations for cleaning and repair activities. This type of analysis can be beneficial in determining if boat capacity is adequate or if the addition of fleet space is justified. 2 ITERATIVE TECHNIQUE 2.1 Iterative Process FlowThe objective of this technique is to determine an optimal, ‘realistic’ solution to an optimization problem, a linear program in this example. A realistic solution refers to a feasible solution generated by the optimization that is also ‘feasible’ in the simulation model. This makes the results feasible based on both the optimization and simulation given the differing constructs and rules in both models.The basis for the proposed iterative approach to opti-mization and simulation is shown below in Figure 2. Boxes shown with a dashed line represent steps that are performed by a computer while a skilled analyst carries out the other steps.The following sections correspond to the numbered elements in Figure 2.2.2 Solve Optimization ModelThe first step in the iterative process involves solving the op-timization model and determining a solution to that model. The optimization model can be solved using any an avail-able solver, depending on the optimization technique ap-plied. Thus, this is a computer performed task in the proc-ess. The results of this run may or may not yield a feasible solution to the optimization model. This step could involve either solving the initial optimization model developed or solving an optimization problem with parameters that have been modified through the iterative process.2.6 Determine Infeasible ParametersOnce the current solution to the simulation is determinednot to be ‘realistic feasible,’ the analyst will then determinewhich parameters from the optimization model led to a‘non-realistic feasible’ solution. This is a step performedmanually by the analyst. Determining which factors areinfeasible will be based on the list of performance meas-ures discussed in the previous step. Each performancemeasure will have specific optimization parameters associ-ated with it. These are the parameters from the optimiza-tion model that affect the performance measure in thesimulation model. Thus, the performance measures thatare not at acceptable levels, as previously determined, willbe used to determine which parameters are to be modifiedin the optimization model.2.7 Determine which Parameters to ModifyBased on step (5), the infeasible parameters will have beendetermined by the analyst. This step involves determiningwhich of those infeasible parameters to modify in the opti-mization model. This is a decision making step performedby the analyst. The determination of which parameters tomodify when more than one is identified will be based on aranking system. This ranking may be based on a sensitivityanalysis of the parameters, percent variation from acceptablevalues of the performance measures, or other cost factors.One parameter will be changed per iteration so that the ef-fects of changing each parameter are clear. This will aid indetermining when to stop the iterative procedure because a‘feasible realistic’ solution has been reached.Figure 2: Flow between Simulation and OptimizationModels2.3 Send Optimization Parametersto SimulationThe next step is to send the results and parameters of theoptimization model to the simulation model. The initialsimulation model is based on the same parameters as theinitial optimization model. This step is performed manu-ally. The analyst determines which parameters to send tothe optimization program and manually includes those de-termined parameters in the simulation model.2.8 Modify Optimization Model2.4 Run Simulation ModelThis step involves manually changing the infeasible pa-rameter in the optimization model. The analyst manuallymakes the changes to the optimization model. The optimi-zation model is then run again to determine a new solutionand the iterative process returns to the beginning.The simulation model is then run. This is the only othercomputer-performed step in the iterative process. Anysimulation software can be applied. The simulation modelgenerates the predetermined performance parameterswhich are used to determine if the results of the simulationmodel are acceptable.2.9 Is the Current Solution the Final Solution?2.5 Is Current Solution ‘Realistically Feasible’?The determination of whether a termination criterion hasbeen met is likewise a manual decision step performed bythe analyst. It involves determining if the performancemeasures for a ‘realistic feasible’ solution are sufficient tobe the final solution to the iterative process. It is thoughtthat the first ‘realistic feasible’ solution reached will be thefinal solution.This decision making step is performed manually by theanalyst. In this step the results of the simulation are ana-lyzed to determine whether the results and parameters of theoptimization model led to a ‘realistic feasible’ solution in thesimulation model. A solution will be deemed ‘realisticallyfeasible’ if a variety of performance measures generated bythe simulation model are within acceptable levels predeter-mined by the decision maker. This set of statistics as well astheir acceptable values will be determined prior to runningthe simulation model. The performance measures are spe-cific to the system being studied.2.10 Modifying Optimization ParametersThis step involves modifying parameters if a ‘realistic fea-sible’ solution is deemed unacceptable. This may occur ifthe analyst requires an improvement to a specific perform-ance measure. 4 OPTIMIZATION MODELFor this application linear programming was used as the op-timization approach. In general, any optimization procedurecan be applied to the iterative process. In this case linear programming is suitable for the barge transport application.2.11 Final SolutionThis block signifies that a final solution has been reached and the iterative process can be terminated. The final solu-tion will yield a solution that is realistic and feasible for actual operations. The objective function of the LP is to minimize the costs associated with barge movement. These include travel costs relating to the type of boat used to tow the barges and travel distances.The constraints are used to balance the movement of barges within the network, to ensure loading and unloading requirements, and to preserve capacities. These include location and boat capacities. The decision variables in the model are the volume of barges that travel a specific path through the system pushed by a specific boat type over a specified planning horizon. This is based on unload loca-tion and exiting direction of barges. Thus, the results of the LP assign optimal routings by boat type for barge movement, including cleaning and repair locations. 2.12 Information FlowFigure 3 below shows the flow of information throughout the iterative process. Information flows between the opti-mization model, simulation model, and the decision maker.5 SIMULATION MODELArena software was used to develop the simulation model for this test data set. The simulation model is based on the sample data set discussed. The purpose of the simulation model is to make sure that the barge routings determined by the linear program are feasible during river operations. The model can be expanded to include more aspects of the barge transport system.Figure 3: Information Flow of Iterative ProcessAs seen in Figure 3, the optimization model is run with the originally established parameters. These parameters and solutions from the optimization model are used as input to the simulation model. The output from the simulation model are the performance measures. These performance measures are used by the analyst to modify the parameters of the optimization model and then run the optimization model again. The decision maker is key in this process. This step involves linking the performance measures to parameters of the optimization model. Thus, when a performance measure is out of range the parameters tied to that specific perform-ance measure can be modified. The simulation uses the paths generated from the lin-ear program to route barges through the system. The simu-lation model, though, is time dependent. While the LP as-signs locations for barge movements, the simulation model accounts for time spent at each location.This iterative procedure allows different levels of detail to be included in the optimization and simulation models. In this application there are two types of barges which are han-dled differently. The optimization model does not differen-tiate based on barge type because the number of covered barges is small (less than 5% of the total barges handled). The simulation model specifies the barge type, covered or flatbed. This ensures that specific barge type requirements do not cause performance measures to become out of range. A skilled analyst is required for decision making in the proposed procedure. It may be possible through future re-search to automate this step in the process, but the current state of development relies on a human-in-the-loop to as-sess the output from the LP model prior to establishing in-put for the simulation model, and vice-versa. 3 SAMPLE DATA SET6APPLICATION OF ITERATIVE TECHNIQUEA sample data set was developed to test this iterative proc-ess. The data set contains a total of thirteen (13) locations. There are four (4) fleet locations, four (4) loading locations as well as three (3) unloading location as well as two loca-tions specifically devoted to cleaning and repairs. This is in contrast to the actual river system which contains nearly one hundred locations. Three boat types were used for this data set and there are three directions by which barges can enter or leave the system.6.1 Performance Measure SelectionAs detailed in Section 2, the iterative process involves se-lecting performance measures of the simulation model and linking these performance measures to parameters of the optimization model, in this case the LP. For the barge transport example several performance measures are appli-cable. These include but are not limited to the following: total cost of operation, over-utilization of fleet locations, queues at fleet locations, boat waiting time (idle time), tow waiting time, boat utilization per boat type, on time deliv-eries, time barges spend empty and/or unloaded, time barges spend loaded and waiting. Waiting times may in-clude barge days spent waiting for a boat (in other words waiting to move to the next location) while the barge was either empty or loaded. Cost based performance measures may also be used.For the sample data set the performance measures se-lected were the number of barges waiting at each at each fleet location, given a maximum capacity at each location. These measures are automatically generated by Arena. In larger applications more performance measures would be used and performance measures that are not automatically generated would be required. In a real world application the performance measures selected would be key to actual river operations.6.2 Parameter SelectionThe performance measures selected are tied directly to pa-rameters of the optimization model, in the case the LP. It was determined that for the number waiting performance measure, for example, the number of available boats is a relevant parameter as is the capacity at each location. Thus, when the number of barges waiting exceeds the acceptable levels specified the number of available boats can be ad-justed in the LP model or the location capacity can be in-creased. In a larger example the decision as to which pa-rameters to modify could be based on a variety of factors, cost of the change being likely. The question becomes is it more feasible and cost effective to add more boat capacity or to add additional fleet space. For this example the decision was made to modify the number of boats.Presently one parameter is modified for each perform-ance measure. This selection of parameters to modify is the subject of ongoing research.6.3 Iterative ResultsThe LP model was solved through CPLEX. The LP results yield a number of barges, over a specified planning hori-zon, that make a specific series of movements through the system. Thus, the LP results establish a path for barges given their unload location and exit direction. It also speci-fies the type of boat used to move the tow. The planning horizon for this example was thirty (30) days.These established paths and boat type utilizations were used as input to the simulation model. Upon running the simulation model the selected performance measure, num-ber of waiting barges, exceeded the maximum at some fleet locations at a given time. This leaves the decision as to whether to modify the number of available boats or the available space at violating location. As discussed in the previous Section 6.2, the number of available boats was increased by one in the optimization model. The new rout-ings generated by the optimization model were input to the simulation model. Upon running the simulation with the increased number of boats and new routings, the perform-ance measures were all within the required range.This process gives the analyst key information for de-cision making. It shows the analyst the optimal solution to the LP and also why that solution is not feasible on the river. The LP averages boat use and capacities over the thirty (30) day planning horizon. Over the planning hori-zon selected the original number of boats is adequate, but in specific peak situations there are too many barges at a given location. This is the benefit to using both the opti-mization and simulation models. This procedure leaves the decision to the analyst as to whether a boat should be added or the number of waiting barges can be accepted.7 EXTENSIONS AND CONCLUSIONSThere are several extensions to this work currently in pro-gress. The simulation model is being expanded to include more details of actual river operations. Various data sets are also being developed to illustrate various aspects of the iterative process. There is also more research to be done in the area of how to best complete the iterative process in-cluding the selection of parameters and performance meas-ures in larger scale models.Developing a large scale model that more closely de-tails river operations will allow the benefits of the process to be clearly identified. The real world applicability of the process depends upon the quality of the models developed. The iterative process, though, allows the user to implement optimization solutions that are guaranteed to be feasible for actual operations. It allows the user to study the actual river system in terms of both the optimization and simula-tion models.REFERENCESAzadivar, Farhad. 1999. Simulation Optimization Method-ologies. In Proceedings of the 1999 Winter Simulation Conference, ed. P.A. Farrington, H.B. Nemhard, G.W.Evans, and D.T. Sturrock, 93-100. Piscataway, New Jersey: Institute of Electrical and Electronics Engineers. Brekke, Kjell Arne and Erling Moxnes. 2003. Do numeri-cal simulation and optimization results improve man-agement?: Experimental evidence.Journal of Eco-nomic Behavior & Organization 50: 117-131.Fu, Michael C., et.al., 2000. Integrating Optimization and Simulation: Research and Practice. In Proceedings of the 2000 Winter Simulation Conference, ed. J.A.Joines, R.R. Barton, K. Kang and P.A. Fishwick, 610-616. Piscataway, New Jersey: Institute of Electrical and Electronics Engineers.Glover, Fred, James P. Kelly, and Manuel Laguna. 1999.New Advances for Wedding Optimization and Simula-tion. In Proceedings of the 1999 Winter Simulation Conference, ed. P.A. Farrington, H.B. Nemhard, G.W.Evans, and D.T. Sturrock, 255-260. Piscataway, New Jersey: Institute of Electrical and Electronics Engineers. Jaccard, Mark, Richard Loulou, Amit Kanudia, John Ny-boer, Alison Bailie, Maryse Labriet. 2003. Methodo-logical Contrasts in Costing Greenhouse Gas Abate-ment Policies: Optimization and simulation modeling of micro-economic effects in Canada. European Jour-nal of Operational Research 145: 148-164.Morito, Susumi, Jun Koida, Tsukasa Iwama, Masanori Sato,Yosiaki Tamura, 1999.Simulation-based con-straint generation with applications to optimization of logistic system design.In Proceedings of the 1999 Win-ter Simulation Conference, 531-536. Piscataway, New Jersey: Institute of Electrical and Electronics Engineers. Swisher, J.R., P.D. Hyden, S.H. Jacobson L.W. Schruben.2000. A survey of simulation optimization techniques and procedures. In Proceedings of the 2000 Winter Simulation Conference, ed. J.A. Joines, R.R. Barton, K.Kang and P.A. Fishwick, 119-128. Piscataway, New Jersey: Institute of Electrical and Electronics Engineers. AUTHOR BIOGRAPHIESAMY BUSH is a Ph.D. candidate in Industrial Engineering at the University of Louisville. She received her M.S. from the University of Alabama in Huntsville in Civil/Environmental Engineering and her B.S. from Purdue University in Industrial Engineering. She was previously employed as an industrial engineer and a corporate trainer. Her current interests are in the application of operations research and simulation. Her e-mail address is <a0bush01@>. WILLIAM E. BILES is the Edward R. Clark Chair of Computer Aided Engineering in the Department of Indus-trial Engineering of the University of Louisville. He re-ceived the BSChE in Chemical Engineering from Auburn University, the MSE in Industrial Engineering from the University of Alabama in Huntsville, and the PhD in In-dustrial Engineering and Operations Research from Vir-ginia Tech. Dr. Biles served on the faculties of the Univer-sity of Notre Dame, the Pennsylvania State University, and Louisiana State University before coming to the University of Louisville in 1988. He has been engaged in teaching and research in simulation for three decades. His most recent areas of research are in web-based simulation and the simulation of water-borne logistics. GAIL W. DEPUY, Ph.D., P.E. is an Associate Professor of Industrial Engineering at the University of Louisville in Louisville, Kentucky. Her research focus lies in the areas of production planning, process planning, and operations research. She received her Ph.D. in Industrial and Systems Engineering from The Georgia Institute of Technology, her M.S. in Industrial and Operations Research from Virginia Polytechnic Institute and State University, and her B.S. in Industrial Engineering from North Carolina State Univer-sity. Dr. DePuy has authored over 40 technical papers and has served as Principal Investigator or Co-Principal Inves-tigator on over $800,000 of funded research. Dr. DePuy is a professional engineer and a member of the Institute of Industrial Engineers, Institute of Operations Research and Management Science, Society of Manufacturing Engi-neers, and American Society for Engineering Education.。

从目的论三原则视角看《恐惧教堂—科学神教里的奇异世界》的翻译

从目的论三原则视角看《恐惧教堂—科学神教里的奇异世界》的翻译一、本文概述《从目的论三原则视角看《恐惧教堂—科学神教里的奇异世界》的翻译》是一篇以翻译理论为研究对象的论文，旨在探讨德国翻译理论家汉斯·弗米尔（Hans Vermeer）提出的目的论三原则在翻译实践中的应用。

本文选取《恐惧教堂—科学神教里的奇异世界》这一作品作为研究案例，分析译者在翻译过程中如何遵循目的原则、连贯性原则和忠实性原则，以实现翻译的预期目的和效果。

文章首先介绍了目的论三原则的基本概念和内涵，包括目的原则、连贯性原则和忠实性原则。

然后，结合《恐惧教堂—科学神教里的奇异世界》这一作品的具体翻译实践，分析了译者在处理文化、语言、修辞等方面的翻译难题时，如何灵活运用目的论三原则，以实现翻译的准确性、流畅性和可读性。

通过本文的研究，不仅可以深化对目的论三原则的理解，还可以为类似科幻文学作品的翻译实践提供有益的借鉴和参考。

本文也期望能够促进翻译理论与实践的结合，推动翻译学科的发展和创新。

二、目的论翻译理论及其三原则目的论翻译理论是由德国翻译学家汉斯·弗米尔在20世纪70年代提出的，它突破了传统等值理论的束缚，为翻译研究提供了新的视角。

在目的论翻译理论中，翻译被视为一种有目的的交际行为，其首要原则是“目的原则”（Skopos rule），即翻译应服务于特定的目的或功能。

这一原则强调了翻译活动在实际应用中的灵活性和多样性，使得翻译可以根据不同的需求和语境进行调整和改变。

目的论翻译理论的另外两个重要原则是“连贯性原则”（Coherence rule）和“忠实性原则”（Fidelity rule）。

连贯性原则要求译文必须符合语内连贯（intra-textual coherence）的标准，即译文必须对于具有目的语交际环境和文化背景的读者是可理解的。

这意味着翻译应考虑到目标读者的语言习惯、文化背景和接受能力，确保译文在目标语言文化中具有意义并易于理解。

REGULATIONS OF THE HONG KONG SPECIAL ADMINISTRATIVE REGION 2003

REGULATIONS OF THE HONG KONG SPECIAL ADMINISTRATIVE REGION 2003
Index to 30 November 2003 to Local Regulations and Notices of Commencement Dates —————— Date of Gazette L.N. No. LOCAL REGULATIONS, ETC. A Administration of Estates by Consular Officers Ordinance (Cap. 191)— ( 191 ) Administration of Estates by Consular Officers Ordinance (Amendment of Schedule) Order 2003 .......................... 4. 7.2003 2003 ) ( ............................................... 4. 7.2003 Page
B2153 B2152
Births and Deaths Registration Ordinance (Cap. 174)— ( 174 ) Births and Deaths Registration Ordinance (Amendment of First Schedule) Order 2003 .......................... 2. 5.2003 2003 ( 1) .. 2. 5.2003
4
INDEX TO LOCAL REGULATIONS, ETC.
Date of Gazette L.N. No. B Banking (Amendment) Ordinance 2002 (6 of 2002)— 2002 6 ) 16 16 ( ) (2002

Lower urinary tract symptoms

Lower Urinary Tract Symptoms, Benign Prostatic Hyperplasia, and Sexual DysfunctionJonathan K. Park, BA, Tobias S. Köhler, MD, MPH,and Kevin T. McVary, MDCorresponding authorKevin T. McVary, MDDepartment of Urology, Northwestern University Medical School, Tarry 16-749, 303 East Chicago Avenue, Chicago, IL 60611, USA.E-mail: k-mcvary@Current Bladder Dysfunction Reports 2008, 3:233–240Current Medicine Group LLC ISSN 1931-7212Copyright © 2008 by Current Medicine Group LLCPreviously viewed as independent processes, sexual dys-function (SD) and lower urinary tract symptoms (LUTS) frequently associate and signiﬁ cantly detract from overall quality of life for men. Analysis of historic and emerging literature using some of the Bradford-Hill criteria argues causality between the two disease processes, with most data focusing on the interplay between LUTS and erectile dysfunction. Understanding of the relationship between SD and LUTS is crucial given the current societal age demographics leading to an increased pool of affected patients. Additional information on risk factors for either disease could potentially improve patient screening, and many currently available treatments (medical and surgical) for SD impact LUTS and vice versa.IntroductionLower urinary tract symptoms (LUTS) and sexual dysfunc-tion (SD) are two highly prevalent disease processes that affect aging men [1,2]. Previously viewed as independent processes, these diseases frequently associate and signifi-cantly impact overall quality of life for men [2,3]. Almost all accepted therapies for LUTS (surgical or medical) can impact some aspect of sexual health, and treatments for SD can also affect LUTS [4,5]. The current literature describing the interplay of LUTS and SD predominantly focuses on erectile dysfunction (ED) but can also relate to ejaculatory dysfunction (EJD) [5]. Furthermore, the link between LUTS and sexual function is not restricted to men, as there appears to be a link between female sexual dysfunction and LUTS or incontinence [6–8].In the context of an increasingly aging population and the current environment of expanding indications for intervention, a more in-depth understanding of the rela-tionship between LUTS and sexual function is needed. Because the link between LUTS and sexual function seems to affect men and women, this knowledge will benefi t all patients and health care professionals.To further understand the relationship between LUTS and ED, one must apply some of the Bradford-Hill criteria to the mounting body of epidemiologic evidence to sepa-rate causal from noncausal explanations. Cross-sectional epidemiologic data, case-control reports, and cohort studies grounded by supportive plausible mechanisms are assessed to further comprehend the epidemiologic evidence. Data are examined for the strength of associa-tion through assessing RR, consistency between studies (replication of fi ndings), dose-response effect, and the presence of a temporal relationship between index disease development and progression or cessation. Most impor-tantly, the observed epidemiologic data must not only account for alternative explanations, such as chance, bias, and confounders, but must also be biologically plausible. The current review summarizes our understanding of the epidemiologic relationship between LUTS and sexual dys-function and offers four potential biologic mechanisms to explain these interactions.The Epidemiologic Relationship Between LUTS and Sexual DysfunctionAge is widely recognized as one of the most important risk factors for SD. The preponderance of epidemio-logic data linking LUTS to SD pertains to ED but also includes EJD and female SD. Men in their 50s have a twofold increase in their RR of ED compared with men in their 40s [9•]. Men are increasingly burdened with ED as time progresses, and most of these men have advanced symptoms. These fi ndings were demonstrated by the Massachusetts Male Aging Study (MMAS), which showed that 52% of men ages 40 to 70 have234 Male Voiding Dysfunctionsome degree of ED and also that two thirds of these men manifest moderate to severe symptoms [1].Paralleling the trend with ED, the prevalence of gross, potentially clinically signifi cant benign prostatic hyperpla-sia (BPH) lesions positively correlates with increasing age. Studies show that BPH increases progressively from the fourth (8%) through the eighth (82%) decade of life [10]. Further supporting these studies, the Baltimore Longitudi-nal Study of 1057 men demonstrated that the cumulative prevalence of a history and physical examination–based diagnosis of LUTS or BPH voiding dysfunction increased progressively from 26% to 79% from the fi fth to eighth decade of life [11]. These studies demonstrate that age is a signifi cant risk factor for BPH and sexual dysfunction.Although the aforementioned studies assessed the link between LUTS and SD in men, several studies also documented a comparable prevalence of similar LUTS in aging women, challenging the idea that prostatic change is the cardinal cause of LUTS [12,13]. However, given the potential role of the central nervous system and the blad-der in LUTS, this seemingly surprising relationship seen in women does not weaken the putative argument for a relationship between LUTS and ED [14].Having demonstrated the impact of age on LUTS and sexual function, the next logical step is to assess the possibil-ity of a relationship between LUTS and SD independent of age. One of the fi rst studies to investigate the role between sexual function and LUTS used a cross-sectional, com-munity-based survey and noted that sexual satisfaction correlated negatively with increasing age and LUTS [15]. The RR of ED stratifi ed by the International Prostate Symp-tom Score (IPSS) showed a 3.3-fold increase for symptom scores greater than 19 compared with IPSS scores of zero. Several cross-sectional, questionnaire-based studies have since shown an increased RR of ED in men who also had LUTS [16–18]. However, these studies did not control for confounders such as age through multivariate analysis.Building on these early results, the Multinational Survey of the Aging Male (MSAM-7) study revealed a strong asso-ciation between IPSS score and the level of sexual activity and International Index of Erectile Function (IIEF) score [2]. This study is important, as it demonstrated that the associa-tion between LUTS and ED persisted even after controlling for age and other comorbidities known to impact sexual function, such as diabetes mellitus. This study also empha-sized that sexual activity is common in most men over age 50 and contributes heavily to quality of life.Multiple other reports confi rmed the independent association between ED and LUTS. In Europe, Val-lancien et al. [19] used the IPSS and Danish Prostatic Symptom Score sex questionnaires to evaluate 1274 men older than age 45 who suffered from LUTS. The inci-dence of ED rose from 55% in men with mild LUTS to 70% in men suffering from severe LUTS. After multiple regression analysis, ED was independently associated with the presence of LUTS.Further studies demonstrated that the LUTS–ED independent relationship was upheld even in different demographic populations. Terai et al. [20] used the IPSS and IIEF questionnaires to evaluate 2084 Japanese men undergoing routine health screening. Increasing severity of LUTS was associated with increased incidence of ED, and this relationship persisted even after controlling for age.Other studies have controlled for age and common medical comorbidities. McVary et al. [21] reported a statistically signifi cant association between baseline American Urology Association (AUA) Symptom Index and the various domains of sexual function, such as erec-tile capability, libido, ejaculation, and overall satisfaction with sexual life. There was also signifi cant association between maximum fl ow rate (Qmax) and the various sex-ual function domains, such as libido, erectile capability, ejaculation, problem assessment, and overall satisfaction with sexual life (P < 0.001 for each domain). The rela-tionship between Qmax, total prostate volume, transition zone volume, and ED noted in the Medical Therapy of Prostatic Symptoms (MTOPS) study is crucial, as it links ED symptoms with more fundamental physiologic and biologic measures of bladder and prostate dysfunction. Importantly, statistical signifi cance remained even after performing a multivariate analysis with excellent subject characterization that controlled for ED comorbidities such as age, partner status, marital status, hypertension, lipid disorders, and diabetes. Also, the duration of LUTS associated very strongly with erectile function, problem assessment, and the overall satisfaction with sexual life (P < 0.01). These results strongly support the idea that the association between LUTS and sexual dysfunction is independent of the usual comorbidities.The preponderance of the evidence for studies between LUTS and ED fulfi ll the Hill’s Causality criteria for strength of association, internal consistency, and dose-response effects (worse LUTS equals worse ED) (Table 1).The issue of an alternate explanation to account for the LUTS–ED association appears to be satisfi ed by several large studies that use multiple regression analyses (and thus minimize confounding), after which the LUTS–ED rela-tionship remains signifi cant [2,19–22]. The requirement of LUTS–ED temporality had not been satisfi ed until recently, with the publication of three studies in which the adminis-tration of a phosphodiesterase (PDE) inhibitor resulted in an immediate improvement of LUTS [4,23•,24,25].As demonstrated, LUTS signifi cantly correlates with ED; however, the MSAM-7 additionally noted that LUTS also correlates with EJD. Moreover, the study showed that the severity of ejaculatory problems increases with wors-ening LUTS [2]. The cumulative results of the MSAM-7 suggest that although older men still actively engage in sexual activity, the severity of LUTS affects their ability to perform, independent of other risk factors.Several medical and surgical treatments for LUTS nega-tively impact ejaculatory function. The 2003 AUA BPHLUTS, BPH, and Sexual Dysfunction Park et al.235guidelines reported EJD for tamsulosin to be 10%; inter-estingly, the highest rates reported for other drugs in the α-blocker class, such as doxazosin and terazosin, were 0% and 1%, respectively [26]. A recent study revealed that the most common aspect of EJD associated with tamsulosin is not retrograde ejaculation, but decreased volume of ejacu-late, followed by anejaculation [27]. In contrast, the samestudy reported no anejaculation with alfuzosin, further236 Male Voiding Dysfunctionsuggesting that the effect is unique to tamsulosin within the α-blocker class. Rates of EJD for another commonly used BPH medication, fi nasteride, are reported at 4% [26].The surgical treatment for LUTS also impacts EJD. The frequency of EJD was reported at 65% with transurethral resection of prostate (TURP); 5% to 16% with transure-thral wave thermotherapy (TUMT); 4% with transurethral needle ablation (TUNA); and 2% for sham controls [26]. These surgical options correlate with EJD and, to a varying extent, with ED. ED incidence has been reported as 10% with TURP, 1% with TUMT, 3% for TUNA, and 2% for sham controls [26]. Although most studies report worsen-ing ED with TURP compared with less invasive treatments, one study reported amelioration of ED following TURP and no signifi cant differences in erectile function between TURP and laser therapy [28].Sexual dysfunction following non-LUTS surgery is common. Elevated rates of SD have occurred following open aortic aneurysm repair, colorectal resection, and orthopedic joint replacement surgery [29–31]. These studies highlight the possibility that surgical procedures in general may result in SD. Alternatively, those with baseline ED or other sexual disorders may not have had a chronologic event with which to associate the onset of their disease, thus spuriously indicting their operation as a potential cause. These scenarios provide a conceptual rationale for possible prior overestimation of sexual dys-function following LUTS surgery.While various investigators have examined the link between LUTS and SD in men, studies have also exam-ined a potential link in women [6–8]. Salonia et al. [6] compared women with and without LUTS/urinary incontinence (UI) and found that women with urinarycomplaints noted signifi cantly more sexual dysfunction than women lacking urinary complaints. Furthermore, a study by Özel et al. [7] suggested that the presence of pelvic organ prolapse exacerbated SD in women with UI. In 2008, Dalpiaz et al. [8] sought to further develop the link between LUTS/UI and female SD. Although the rea-son for this link remains unclear, the investigators assert that the cause is likely multifactorial and may include a psychological basis (namely, the fear of urinary leakage during intercourse).Biological Plausibility: Mechanisms of Interaction Between LUTS and EDTo support the epidemiologic evidence of a relationship between LUTS and sexual dysfunction, a biologically sen-sible mechanism explaining the interaction is required. To date, possible biologic interrelationships between LUTS and ED fall into four related physiologically relevant theories (Fig. 1).NOS/NO levels decreased or altered in the bladder, prostate, and penile smooth muscleThis hypothesis asserts that reduced production of nitric oxide synthase (NOS) and/or nitric oxide (NO) in the pel-vis (bladder, penis, and prostate) explains the link between ED and LUTS [32]. This theory incorporates the nitrergic innervation–smooth muscle cell relaxation molecular mechanism of ED. It also elegantly unifi es both disease processes because it is reported that NOS/NO production of the prostate is reduced in BPH (transition zone) com-pared with normal prostate tissue. Prostate tissue levels of NOS/NO are reduced in BPH progression, which then reduces prostatic tone relaxation, leading to LUTS [33]. The LUTS–ED, NOS/NO theory is further supported by the characterization and functional relevance of cyclic nucleotide PDE isoenzymes of the human prostate [34], the most common PDEs found in prostate tissue being PDE type 4 and PDE type 5.It was shown recently that PDE5 mRNA is found in greatest quantity in the human corpora cavernosa (~ 10-fold higher); however, PDE5 mRNA was also found in order of decreasing magnitude over the vas deferens, prostate, epi-didymis, bladder (immunolocalized to vascular endothelium and muscle fi bers only), testis, and kidney [35]. Conversely, rat PDE5 is expressed highest in the bladder, about 10-fold higher than rat corpora cavernosa, followed in decreas-ing prevalence by the vas deferens, prostate, kidney, testis, and epididymis [36]. All PDE5 inhibitors inhibited cGMP catabolizing activity in human bladder cells and rat bladder strips and induced a consistent antiproliferative and relax-ant effect, supporting the idea of the role of NO/NOS in the urinary system.To further characterize the pelvic PDE profi le, Fawcett et al. [37] performed Northern and RNA dot blots forPDE11A gene expression and isolated its presence in testes,Figure 1. Potential linkages in the pathophysiology among the four proposed mechanisms for the association between lower urinary tract symptoms and erectile dysfunction. A—agonist; DAG—dia-cylglycerol; IP 3—inositol triphosphate; MLC—myosin light chain; MLC-P—myosin light chain-phosphatase; PKC—protein kinase C; PLC—phospholipase C; R—receptor; SR—sarcoplasmic reticulum.LUTS, BPH, and Sexual Dysfunction Park et al. 237skeletal muscle, and the prostate. Type 11A protein abun-dance was greatest in the prostate compared with other organs. Although the role of prostatic PDE11A is unknown, its relatively low abundance in the smooth muscle makes its pivotal role in the LUTS–ED relationship less likely. Thus, based on these studies, it is apparent that PDE5 may have a signifi cant role in the pathogenesis of LUTS and ED.With the apparent biologic basis of a role for PDE in the prostate and bladder, the next logical step is to translate this hypothesis into a useful clinical tool. The concept that PDE5 inhibitors could be used to improve LUTS is provocative, fueling three recent studies seeking to elucidate the relationship between these two important diseases in a randomized, placebo-controlled fashion [23•,24,25]. McVary et al. [4,24] performed a 12-week, double-blinded, placebo-controlled study of sildenafi l in 369 men 45 years old or older who had IIEF scores less than 26 and IPSS scores greater than 11. Compared with placebo, patients in the sildenafi l group demonstrated improved IIEF scores and emotional well-being, as well as greater treatment satisfaction (P < 0.0001).Stief et al. [25] performed a study on 221 men 45 to 64 years old who had an IPSS greater than 11 at time of random-ization before 8 weeks of treatment with 10 mg of vardenafi l twice a day versus placebo [25]. After 8 weeks of treatment, the total IPSS score in the vardenafi l group improved signifi -cantly compared with placebo (P = 0.0013).The study by McVary et al. [23•] with tadalafi l likely yields the most reliable fi ndings given its trial design. The magnitude of IPSS improvement observed compared similarly with results reported in α-blocker studies. Taken together, these three studies consistently demonstrated tem-porality between LUTS and ED. As for the specifi c site of action of the PDE5 inhibitors, a recent study in spinal cord injury patients demonstrated improvements in maximum cystometric capacity and increase in detrusor overactivity volume value, suggesting that the site of action by PDE5 inhibitors in alleviating LUTS is the bladder [38].Autonomic hyperactivity and metabolic syndrome effects on LUTS, prostate growth, and EDThe autonomic nervous system (ANS) plays an important role in the control of prostate growth and differentiation [39]. Using a rat model, McVary et al. [39] demonstrated that the ANS provides an environment that induces rat prostatic growth, whereas its absence leads to glandular regression. These fi ndings were supported by additional animal studies using spontaneously hypertensive rats (SHR) that developed increased autonomic activity, prostate hyperplasia, and ED [40,41]. Following brief but aggressive hypertension treat-ment, erectile function improved [41]. These effects may be related to improvement in structurally based vascular resis-tance within the penis and the decrease in responsiveness of α1-adrenoceptor–mediated erectolytic signaling.The metabolic syndrome, which includes glucose intolerance, hypertension, hyperlipidemia, and centralobesity, also incorporates autonomic hyperactivity. It is an attractive theory because it explains the association of the metabolic syndrome with LUTS and ED and also links established clinical physiologic fi ndings of LUTS, BPH, and ED with established basic science evidence [32]. However, it remains unclear whether the increase in LUTS or ED is the result of a central increase in sensitiv-ity to peripheral signals, or a consequence of an alteration in the function of the bladder and penis that generates increased central activation. Autonomic hypersensitivity may also impact smooth muscle relaxation and penile responsiveness through increasing sympathetic tone. The encouraging results of early laboratory research warrant future studies to further elucidate the precise mechanism linking autonomic hyperactivity to LUTS and ED.Animal studies suggesting that autonomic hyperactiv-ity contributes to increased prostate growth are bolstered by epidemiologic investigations linking the clinical diag-nosis of BPH with increased autonomic tone. The ANS is intimately involved in voiding mechanisms, and recent evidence shows that ANS hyperactivity is signifi cantly associated with BPH signs and symptoms, as well as the most commonly used measures of LUTS (AUA symptom score and BPH Impact Index score) [42]. As a result, fur-ther knowledge of autonomic hyperactivity will provide a better understanding of the pathophysiology of BPH, prostate growth, and ED. Thus, ANS hyperactivity is a plausible biological theory that potentially helps to explain the epidemiologic linkage between ED and LUTS.The alternate pathway: Rho-kinase activationInvestigators have suggested that the so-called alternate pathways of smooth muscle relaxation and contraction may be responsible for the relationship between ED and bladder outlet obstruction (BOO) [32]. Phosphorylation and dephosphorylation of myosin light chain (MLC) are the primary mechanisms of regulating smooth muscle contractility and are in part modulated by MLC phos-phatase (MP). It has been shown that MP is regulated by the protein Rho-kinase. Rho-kinase inhibits MP, lead-ing to an elevation of MLC phosphorylation without an accompanying increase in calcium concentration, a phe-nomenon referred to as calcium sensitization of smooth muscle [43]. Given the intricate role of Rho-kinase in smooth muscle contraction, it is not surprising that Rho-kinase is associated with increased bladder tone and prostatic smooth muscle proliferation, leading to BOO (Fig. 2A, Fig. 2B) [44•].Given the role of Rho-kinase in BOO, it is a potential target for drug inhibitor therapy, possibly by reducing the effects of BPH [44•]. In the previously mentioned SHR model, it was also found that Rho-kinase inhibitors sig-nifi cantly suppressed bladder overactivity [45]. Different isoforms of Rho-kinase have been characterized recently, suggesting that alterations in the isoform profi le may be part of a molecular mechanism of bladder adaptation238 Male Voiding Dysfunctionfollowing BOO [46]. Further isoform characterization will aid efforts to target a specifi c Rho-kinase variant for treatment of LUTS.The suggestion that BOO induces ED via an upreg-ulation of Rho-kinase in the penis has experimental merit. Multisystem dysfunction of Rho-kinase may also occur, leading to both LUTS and ED. Evidence from a rabbit study demonstrated increased basal corpus cav-ernosum smooth muscle (CCSM) tone associated with an elevated level of smooth muscle myosin phosphory-lation in BOO rats compared with control rats [47]. Furthermore, Rho-kinase was higher in the CCSM of the BOO group than that of the control group [48]. This study also illustrated that Rho-kinase inhibitors produce CCSM relaxation, reinforcing the idea that Rho-kinase is involved in the pathophysiology of both LUTS and ED and that it may also serve as a therapeu-tic target for both disease processes.Pelvic atherosclerosis as a mechanism for LUTS and ED An additional hypothesis causatively linking LUTS andED is diffuse atherosclerosis of the prostate, penis, and bladder [49]. The proponent theorized that several ED risk factors (hypertension, smoking, hypercholesterol-emia, and diabetes mellitus) also impact LUTS and BPH.The hyperlipidemic rabbit model demonstratesincreased prostate weight, bladder overactivity, and ED after being fed a high-fat diet [50]. Potential mechanisms include hypoxia-induced overexpression of transforming growth factor-β1 and altered prostanoid production. Penile ischemia results in smooth muscle loss and ED. An analogous loss of smooth muscle in the bladderwould decrease compliance and worsen LUTS. Similarly, bladder ischemia resulting from BOO or pelvic vascular disease can induce bladder smooth muscle loss, result-ing in collagen deposition and fi brosis, as well as loss of compliance, hyperactivity, and impaired contractility [50]. Loss of smooth muscle in the prostate causes a less distensible urethra, increased fl ow resistance, decreased urinary fl ow rate, and worsening LUTS. The pelvic ath-erosclerosis theory holds appeal because it integrates the other LUTS/ED theories, in that pelvic ischemia may induce ANS hyperactivity, reduce NOS expression, and upregulate Rho-kinase [3].ConclusionsLUTS and sexual dysfunction are highly prevalent in aging men. It is well established that LUTS and SD inde-pendently reduce quality of life. In combination, these two clinical entities logically compound life distress.The literature supporting an age- and comorbidity-independent association between LUTS and SD is strong, consistent, and demonstrates a dose response. The link between LUTS and ED has biologic plausibility given the four leading theories of how these diseases interrelate. It is possible that these theories collectively contribute to theoverall pathogenesis of LUTS and ED.Recent studies showing a clear improvement in LUTS with the use of effective ED treatment of PDE5 inhibitors demonstrate the strongest evidence to date that these two disease processes are temporally and causally related, notsimply coincidental.Understanding the relationship between SD and LUTS is essential because additional information on risk factors for either disease could be important for patient screen-ing, population demographics reveal an increasing pool of affected men, and many currently available treatments for one disease affect the other [4,5].Establishing the evolving relationship of LUTS and SD will allow further insight into the etiology of LUTS. Using PDE inhibitors as prophylaxis for LUTS, or as a primary treatment for the LUTS/overactive bladder, seems a viable future possibility. Furthermore, treatment of LUTS with PDE inhibitors could potentially be used to treat LUTS in female patients.Figure 2. A and B , The role of Rho-kinase in smooth muscle relaxation and erectile dysfunction (ED). LUTS—lower urinary tract symptoms;MLC—myosin light chain; MLC-P—myosin light chain-phosphatase; NO—nitric oxide; NOS—nitric oxide synthase.LUTS, BPH, and Sexual Dysfunction Park et al.239DisclosuresDr. McVary is consultant for Pfi zer; a consultant for, speaker for, and recipient of grant support from Eli Lilly and Company; a speaker for and recipient of grant support from GlaxoSmithKline; and a speaker for and recipient of grant support from Sanofi. No other potential confl icts of interest relevant to this article were reported. References and Recommended ReadingPapers of particular interest, published recently,have been highlighted as:• Ofimportance•• Of major importance1. Feldman HA, Goldstein I, Hatzichristou DG, et al.:Impotence and its medical and psychosocial correlates:results of the Massachusetts Male Aging Study. J Urol 1994,151:54–61.2. Rosen R, Altwein J, Boyle P, et al.: Lower urinary tractsymptoms and male sexual dysfunction: the multinationalsurvey of the aging male (MSAM-7). Eur Urol 2003,44:637–649.3. McVaryKT:Erectile dysfunction and lower urinary tract symptoms secondary to BPH. Eur Urol 2005, 47:838–845. 4. McVary KT, Monnig W, Camps JL Jr, et al.: Sildenafi l citrateimproves erectile function and urinary symptoms in menwith erectile dysfunction and lower urinary tract symptomsassociated with benign prostatic hyperplasia: a randomized,double-blind trial. J Urol 2007, 177:1071–1077.5. LeporH:Phase III multicenter placebo-controlled study of tamsulosin in benign prostatic hyperplasia. TamsulosinInvestigator Group. Urology 1998, 51:892–900.6. Salonia A, Zanni G, Nappi RE, et al.: Sexual dysfunctionis common in women with lower urinary tract symptomsand urinary incontinence: results of a cross-sectionalstudy. Eur Urol 2004, 45:642–648; discussion 648.7. Özel B, White T, Urwitz-Lane R, Minaglia S: The impactof pelvic organ prolapse on sexual function in womenwith urinary incontinence. Int Urogynecol J Pelvic FloorDysfunct 2006, 17:14–17.8. Dalpiaz O, Kerschbaumer A, Mitterberger M, et al.: Femalesexual dysfunction: a new urogynaecological research fi eld.BJU Int 2008, 101:717–721.9.• McVaryKT:Clinical practice. Erectile dysfunction. N Engl J Med 2007, 13, 357:2472–2481.This review offers an excellent overview of ED pathophysiologyand treatment and recommendations for clinical use to aid patient evaluation and management.10. Berry SJ, Coffey DS, Walsh PC, Ewing LL: The developmentof human benign prostatic hyperplasia with age. J Urol 1984,132:474–479.11. Guess HA, Arrighi HM, Metter EJ, Fozard JL: Cumu-lative prevalence of prostatism matches the autopsyprevalence of benign prostatic hyperplasia. Prostate1990, 17:241–246.12. Chai TC, Belville WD, McGuire EJ, Nyquist L: Specifi cityof the American Urological Association voiding symptomindex: comparison of unselected and selected samples ofboth sexes. J Urol 1993, 150:1710–1713.13. GrayhackJT:Benign prostatic hyperplasia. The scope of the problem. Cancer 1992, 70:275–279.14. Andersson KE, Gratzke C: Pharmacology of alpha1-adre-noceptor antagonists in the lower urinary tract and centralnervous system. Nat Clin Pract Urol 2007, 4:368–378.15. Macfarlane GJ, Botto H, Sagnier PP, et al.: The relationshipbetween sexual life and urinary condition in the Frenchcommunity. J Clin Epidemiol 1996, 49:1171–1176.16. Braun MH, Sommer F, Haupt G, et al.: Lower urinary tractsymptoms and erectile dysfunction: co-morbidity or typical“Aging Male” symptoms? Results of the “Cologne MaleSurvey.” Eur Urol 2003, 44:588–594.17. Blanker MH, Bohnen AM, Groeneveld FP, et al.: Correlatesfor erectile and ejaculatory dysfunction in older Dutchmen: a community-based study. J Am Geriatr Soc 2001,49:436–442.18. Moreira ED Jr, Lisboa Lobo CF, Villa M, et al.: Prevalenceand correlates of erectile dysfunction in Salvador, north-eastern Brazil: a population-based study. Int J Impot Res2002, 14:S3–S9.19. Vallancien G, Emberton M, Harving N, van MoorselaarRJ: Sexual dysfunction in 1274 European men suffer-ing from lower urinary tract symptoms. J Urol 2003,169:2257–2261.20. Terai A, Ichioka K, Matsui Y, Yoshimura K: Association oflower urinary tract symptoms with erectile dysfunction inJapanese men. Urology 2004, 64:132–136.21. McVary KT, Foley JP, Slawin KM, et al.: The long termeffects of doxazosin, fi nasteride, and the combination onsexual function in men participating in the MTOPS Trial[abstract 1194]. J Urol 2004, 171:315.22. Elliott SP, Gulati M, Pasta DJ, et al.: Obstructive lowerurinary tract symptoms correlate with erectile dysfunction.Urology 2004, 63:1148–1152.23.• McVary KT, Roehrborn CG, Kaminetsky JC, et al.: Tadala-fi l relieves lower urinary tract symptoms secondary tobenign prostatic hyperplasia. J Urol 2007, 177:1401–1407. This study is of special interest in that it demonstrated improve-ment of LUTS (comparable to α-blocker studies) following use of PDE-5 inhibitor therapy. In doing so, it solidifi ed the temporality between LUTS and ED.24. McVary KT, Kaufman J, Young JM, Tseng LJ: Sildenafi lcitrate improves erectile function: a randomised double-blind trial with open-label extension. Int J Clin Pract 2007,61:1843–1849.25. Stief CG, Porst H, Neuser D, et al.: A randomised, placebo-controlled study to assess the effi cacy of twice-dailyvardenafi l in the treatment of lower urinary tract symptomssecondary to benign prostatic hyperplasia. Eur Urol 2008,53:1236–1244.26. AUA Practice Guidelines Committee: AUA guidelineon management of benign prostatic hyperplasia (2003).Chapter 1: diagnosis and treatment recommendations.J Urol 2003, 170:530–547.27. Hellstrom WJ, Sikka SC: Effects of acute treatment withtamsulosin versus alfuzosin on ejaculatory function innormal volunteers. J Urol 2006, 176:1529–1533.28. Brookes ST, Donovan JL, Peters TJ, et al.: Sexualdysfunction in men after treatment for lower urinary tractsymptoms: evidence from randomised controlled trial.BMJ 2002, 324:1059–1061.29. Jimenez JC, Smith MM, Wilson SE: Sexual dysfunction inmen after open or endovascular repair of abdominal aorticaneurysms. Vascular 2004, 12:186–191.30. Jayne DG, Brown JM, Thorpe H, et al.: Bladder andsexual function following resection for rectal cancer ina randomized clinical trial of laparoscopic versus opentechnique. Br J Surg 2005, 92:1124–1132.31. Nordentoft T, Schou J, Carstensen J: Changes in sexualbehavior after orthopedic replacement of hip or knee inelderly males—a prospective study. Int J Impot Res 2000,12:143–146.32. McVary KT, McKenna KE: The relationship betweenerectile dysfunction and lower urinary tract symptoms:epidemiological, clinical, and basic science evidence.Curr Urol Rep 2004, 5:251–257.33. Bloch W, Klotz T, Loch C, et al.: Distribution of nitricoxide synthase implies a regulation of circulation, smoothmuscle tone, and secretory function in the human prostateby nitric oxide. Prostate 1997, 33:1–8.。

学生对反函数概念的理解

从上述图表中可以看出，５０％以上的高一学生对反函数概念定义的回答还处于水平一（前结构水平），高二学生在四个水平上的分布相对来说是比较均匀的，高三大部分学生处在水平二（单结构水平）和水平三（多结构水平）上。

让人感到意外的是，对反函数概念定义的回答达到水平四（关联水平）的高二学生远远多于高三学生，水平四上的高一和高三学生人数百分比是相当的。

ｖｉｎｎｅｒ的关于定义与概念表象关系的理论，在这里或许能够作为一个很好的解释：学生在学习过程中不断建构反函数概念的表象，而反函数概念的定义在建构中起到了“协助”作用，是概念形成的脚手架，随着概念表象建构得越来越准确，直到反函数概念大厦筑成之后，他们再次看到“反函数”一词时的反应一般就不再拘泥于定义的形式，而是有了自己完善的理解。

在本研究后面的分析中我们也将会看到，事实上，高三学生在解答题目的表现上确实是好于其他两个年级的。

图２显示了三个年级所有学生对反函数概念定义回答水平的比较。

塑墼堡垒重墨旦查查！塑！！趣一从上述图表中可以看出，学生对反函数概念定义的回答一般可以达到水平二和水平三：由于高一有一半以上学生的回答还处于水平一，所以，尽管高二、高从表２中可以看出，就年级来讲，学生呈现出的各种理解的总频数高二年级为１０８次，比学生数高出９２．９％；高三年级为６１次，比学生数高出４５．２％；高一年级为６５次，比学生数高出２２．２％。

就总体来讲，学生呈现出的各种理解的总频数为２３４次，比学生数高出５３．９％。

比学生数高出的百分比越大，说明有些学生回答中呈现出的概念表象越多，从而可以说明学生对反函数概念定义各个侧面的理解越全面。

以上数据表明对反函数概念定义理解的全面程度从高到低依次为高二年级、高三年级和高一年级。

从上述图表中学生呈现出的各种理解来看，高一年级学生的“无／错表象”在各种理解中是最高的，达４４．６％，而高二和高三年级学生的“无／错表象”一类在各种理解中仅分别占１２．Ｏ％和１１．５％。

蛋白质相互作用研究中的计算方法综述

（１ｉｚｊ＠ｂｕａａ．ｅｄｕ．ｃｎ）
ＡＳｕｒｖｅｙｏｆＣｏｍｐｕｔａｔｉｏｎａｌＭｅｔｈｉｎＰｒｏｔｅｉｎ—ＰｒｏｔｅｉｎＩｎｔｅｒａｃｔｉｏｎＲｅｓｅａｒｃｈ
ＬｉＺｈｏｕｊｕｎｌ～，ＣｈｅｎＹｉｍｉｎ９１～，ＬｉｕＪｕｎｗａｎｌ一，ａｎｄＣｈｅｎＨｕｏｗａｎ９１ ’（ＣｏｌｌｅｇｅｏｆＣｏｍｐｕｔｅｒ。ＮａｔｉｏｎａｌＵｎｉｖｅｒｓｉｔｙｏｆＤｅｆｅｎｓｅＴｅｃｈｎｏｌｏｇｙ，Ｃｈａｎｇｓｈａ４１００７３）２（ＳｃｈｏｏｌｏｆＩｎｆｏｒｍａｔｉｏｎＳｃｉｅｎｃｅａｎｄＴｅｃｈｎｏｌｏｇｙ．ＨｕｎａｎＡｇｒｉｃｕｌｔｕｒａｌＵｎｉｖｅｒｓｉｔｙ，ＣｈａｎｇｅｒＳｃｉｅｎｃｅ＆Ｅｎｇｉｎｅｅｒｉｎｇ，ＢｅｉｈａｎｇＵｎｉｖｅｒｓｉｔｙ，Ｂｅｉｊｉｎｇ１０００８３）４（ＳｃｈｏｏｌｏｆＣｏｍｐｕｔｅｒＳｃｉｅｎｃｅ，ＳｏｕｔｈＣｅｎｔｅｒＵｎｉｖｅｒｓｉｔｙｏｆＦｏｒｅｓｔＳｃｉｅｎｃｅａｎｄＴｅｃｈｎｏｌｏｇｙ，Ｃｈａｎｇｓｈａ４１０００４）
计算机研究与发展ＪｏｕｒｎａｌｏｆＣｏｍｐｕｔｅｒＲｅｓｅａｒｃｈａｎｄＤｅｖｅｌｏｐｍｅｎｔ
ＩＳＳＮ１０００—１２３９／ＣＮ１１—１７７７／ＴＰ４５（１２）：２１２９—２１３７，２００８
蛋白质相互作用研究中的计算方法综述
圆李舟军ｈ３陈义明１’ 刘军万ｈ４
１（国防科学技术大学计算机学院长沙４１００７３）２（湖南农业大学信息科学技术学院长沙４１０１２８）３（北京航空航天大学计算机学院北京１０００８３） ·（中南林业科技大学计算机科学学院长沙４１０００４）
１ＰＰＩ网络的构建
１．１ＰＰＩ的计算预测作为实验手段的重要补充，用计算方法预测蛋

Standard Model

1 Historical background
The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the ﬁfth.
3.1 Fermions
quarks being very strongly bound to one another, forming color-neutral composite particles (hadrons) containing either a quark and an antiquark (mesons) or three quarks (baryons). The familiar proton and the neutron are the two baryons having the smallest mass. Quarks also carry electric charge and weak isospin. Hence they interact with other fermions both electromagnetically and via the weak interaction.
Standard Model
This article is about the Standard Model of particle physics. For other uses, see Standard model (disambiguation). This article is a non-mathematical general overview of the Standard Model. For a mathematical description, see the article Standard Model (mathematical formulation). For the Standard Model of Big Bang cosmology, Lambda-CDM model. The Standard Model of particle physics is a theory con-

《经济学原理》推荐阅读书目

“经济学原理”课程推荐阅读书目（2013年6月修订）本书目所列多为知名经济学家撰写，将经济学基本原理用于思考实际问题，且有趣易懂的书籍。

推荐目的在于培养同学对学习和运用经济学的兴趣。

对于作业和考试并无直接帮助，特别适合在休闲时间（例如假期）阅读。

书目基于Mankiw, Principles of Economics (3rd, 5th and 6th ed.), Suggested Summer Readings / Suggestions for Summer Reading。

并补充了中译本，增删了一些书籍。

排列顺序大致与教材内容平行。

作者相同或内容相近的书籍集中排列，时间有限者可择其一阅读。

The Cartoon Introduction to Economics, by Yoram Bauman, and Grady Klein, New York: Hill and Wang, 2010, 2011.《酷玩经济学》/（美）尤伦·鲍曼、格兰迪·克莱恩著，闾佳译，中国人民大学出版社，2011。

Spin-Free Economics, by Nariman Behravesh, New York: McGraw-Hill, 2008.《这才是经济学：经济学的误解与真相》/（美）纳瑞蒙·贝尔拉夫什著，麻勇爱译，机械工业出版社，2010。

Freakonomics: A Rogue Economist Explores the Hidden Side of Everything, by Steven D. Levitt, and Stephen J. Dubner, William Morrow, 2005.《魔鬼经济学》/（美）史蒂芬·列维特、史蒂芬·都伯纳著，刘祥亚译，广东经济出版社2006。

Philosophy of Science: A Very Short Introduction, Oxford University Press, 2000.《科学哲学》/（英）Samir Okasha著，韩广忠译，凤凰出版传媒集团、译林出版社2009。

村干部交叉任职制度的博弈分析

村干部交叉任职制度的博弈分析∗——兼论制度创新的条件宁泽逵1，屈小博21西安财经学院管理学院，（710061）2西北农林科技大学经济管理学院，（710021）E-mail：ningzekui@摘要：为化解中国农村基层自治体系中所出现的“‘两委’不和”、“两张皮”现象，必须进行制度创新。

通过合理设计“两委”的博弈环境与触发机制，假定为追求执政理念的村级“两委”间的Hotelling博弈弈局必然导致“两委”执政理念的妥协与调和，最终达到相互交融的博弈均衡位置。

这一均衡结果在基层实践中直接表现为“两委”间的交叉任职。

由于乡镇政府能凭籍其绝对强势的政治影响力，可以直接干涉基层“两委”的Hotelling弈局，进而改变博弈均衡位置。

这种干预直接后果表现为村干部交叉任职模式的多样化。

但乡镇政府干预的随机性会导致两委交叉任职模式的不确定性，进而影响到村干部和村民对村级组织政治生活预期的稳定性。

关键词：村干部；交叉任职；囚徒困境；Hotelling博弈1. 引言所谓村干部交叉任职是指村委会成员与村党支部成员互相兼任部分职务。

据文献，早在20世纪80年代中国局部地区基层民主建设中就出现过“两委”（村委会与村党支部的简称，下同）交叉任职现象（商州市情调查组，1993；上杭县情调查组，1994），到20世纪90年代中后期尤为成熟与流行①。

目前，村干部交叉任职已成为中国基层民主改革的重要理念②和实践行为③。

但是，关于村干部交叉任职这种普遍存在、并且正蓬勃发展的社会现象的专门研究并不多：（1）大部分研究成果（如，托马斯·希伯拉、沃夫冈·陶普曼，1995；马戎、刘世定、邱泽奇，2000；王春生，2000）只是将其作为在村民自治过程中的一种普通现象；（2）一部分研究成果则将其作为化解村民自治实践中出现的村级“‘两委’矛盾”的一项政策建议（贺雪峰，2000；王金涛，2000；鲁献启，2000；高旺，2002；李小平，2002；何增科，2003；徐大兵、杨正喜，2003；冯毓奎，2003；冯耀明，2004；姚巧华，2004；王道坤，2004；田东奎，2005）；（3）还有的研究成果侧重于村干部交叉任职对农村妇女参政的影响，但*本文系国家自然科学基金项目“村干部在农村经济管理中的激励与制约机制研究”（项目编号: 70273035 主持人：西北农林科技大学经济管理学院王征兵教授）资助成果。

An overview of new approaches to deep desulfurization for ultra clean gasoline diesel fuel

Catalysis Today86(2003)211–263An overview of new approaches to deep desulfurization for ultra-clean gasoline,diesel fuel and jet fuelଝChunshan Song∗Clean Fuels and Catalysis Program,Department of Energy and Geo-Environmental Engineering,The Energy Institute,Pennsylvania State University,University Park,PA16802,USAReceived6May2003;received in revised form17June2003;accepted18June2003AbstractThis review discusses the problems of sulfur reduction in highway and non-road fuels and presents an overview of new approaches and emerging technologies for ultra-deep desulfurization of reﬁnery streams for ultra-clean(ultra-low-sulfur) gasoline,diesel fuels and jet fuels.The issues of gasoline and diesel deep desulfurization are becoming more serious because the crude oils reﬁned in the US are getting higher in sulfur contents and heavier in density,while the regulated sulfur limits are becoming lower and lower.Current gasoline desulfurization problem is dominated by the issues of sulfur removal from FCC naphtha,which contributes about35%of gasoline pool but over90%of sulfur in gasoline.Deep reduction of gasoline sulfur(from330to30ppm)must be made without decreasing octane number or losing gasoline yield.The problem is complicated by the high oleﬁns contents of FCC naphtha which contributes to octane number enhancement but can be saturated under HDS conditions.Deep reduction of diesel sulfur(from500to<15ppm sulfur)is dictated largely by 4,6-dimethyldibenzothiophene,which represents the least reactive sulfur compounds that have substitutions on both4-and 6-positions.The deep HDS problem of diesel streams is exacerbated by the inhibiting effects of co-existing polyaromatics and nitrogen compounds in the feed as well as H2S in the product.The approaches to deep desulfurization include catalysts and process developments for hydrodesulfurization(HDS),and adsorbents or reagents and methods for non-HDS-type processing schemes.The needs for dearomatization of diesel and jet fuels are also discussed along with some approaches.Overall, new and more effective approaches and continuing catalysis and processing research are needed for producing affordable ultra-clean(ultra-low-sulfur and low-aromatics)transportation fuels and non-road fuels,because meeting the new government sulfur regulations in2006–2010(15ppm sulfur in highway diesel fuels by2006and non-road diesel fuels by2010;30ppm sulfur in gasoline by2006)is only a milestone.Desulfurization research should also take into consideration of the fuel-cell fuel processing needs,which will have a more stringent requirement on desulfurization(e.g.,<1ppm sulfur)than IC engines. The society at large is stepping on the road to zero sulfur fuel,so researchers should begin with the end in mind and try to develop long-term solutions.©2003Elsevier B.V.All rights reserved.Keywords:Desulfurization;Gasoline;Fuels;Diesel fuel;Jet fuel;Catalysis;AdsorptionଝBased on a keynote lecture at the international symposium on Ultra-Clean Transportation Fuels at American Chemical Society National Meeting in Boston,MA,during18–22August2002.∗Tel.:+1-814-863-4466;fax:+1-814-865-3248.E-mail address:csong@(C.Song).1.IntroductionThis review discusses fuel speciﬁcation issues and the problems of sulfur reduction in highway and non-road fuels and presents an overview of new0920-5861/$–see front matter©2003Elsevier B.V.All rights reserved. doi:10.1016/S0920-5861(03)00412-7212 C.Song /Catalysis Today 86(2003)211–263Table 1US EPA Tier II gasoline sulfur regulations as of 2002CategoryYear 1988[7]1995[9]2004[3]2005[3]2006[3]Reﬁnery average (ppmw)1000(maximum)[7]330(<330ppm S and<29.2%aromatics required for national certiﬁcation;<850ppm S and <41.2%aromatics as national maximum)[9]–3030Corporate average (ppmw)12090–Per-gallon cap (ppmw)30030080approaches to ultra-deep desulfurization of reﬁnery streams for ultra-clean (ultra-low-sulfur)gasoline,diesel fuels and jet fuels.In the past decade,clean fuels research including desulfurization has become a more important subject of environmental catalysis studies worldwide.Tables 1and 2show the current US EPA regulations for gaso-line [1–3]and diesel fuels [3–5]including non-road diesel fuels [6],respectively,along with earlier fuel speciﬁcation data in the US for comparison [7–9].With the new US EPA Tier II regulations to reduce the gasoline sulfur from current maximum of 350–30ppm (reﬁnery average,with 80ppm as per-gallon (1US gallon =3.7854l)cap)by 2006,and to cut the high-way diesel fuel sulfur from current 500ppmw down to 15ppmw (per-gallon average)by June 2006,reﬁner-ies are facing major challenges to meet the fuel sulfur speciﬁcation along with the required reduction of aro-matics contents.More recently,EPA has announced plan to reduce non-road diesel fuel sulfur from current average of 3400ppm down to 500ppm by 2007and further to 15ppm by 2010[6].The US Clean Air ActTable 2US EPA sulfur regulations for diesel and jet fuels as of April 2003CategoryYear 1989[8]1993[6]2006[6]2010[6]Highway diesel (ppmw)5000(maximum for no.1D and 2D,with minimum cetane no.40)[8]500(current upper limit since 1993)15(regulated in 2001;exclude some small reﬁneries)15(regulated in 2001;apply to all US reﬁneries)Non-road diesel (ppmw)20000[8]5000(current upper limit)500(proposed in 2003for 2007)15(proposed in 2003for 2010)Jet fuel (ppmw)300030003000maximum?<3000maximum?Amendments of 1990and related new fuel regulations by the US EPA and government regulations in many countries call for the production and use of more en-vironmentally friendly transportation fuels with lower contents of sulfur and aromatics.Table 3shows the average properties of crude oils reﬁned in the US during 1981–2001along with the US and worldwide petroleum consumption dur-ing 1981–2001based on published statistical data [10–14].The demand for transportation fuels has been increasing in most countries for the past three decades.The total world petroleum consumption increased from 49.42million barrels per day (MBPD)in 1971to 77.12MBPD in 2001,representing a 56%increase [11].The total US consumption of petroleum products reached 19.59MBPD in 2001,about 39%increase from 1971(14.11MBPD)[10].Of the petroleum products consumed in US in 2001,8.59MBPD was supplied as motor gasoline,3.82MBPD as distillate fuels,including 2.56MBPD as high-way diesel fuels and 1.26MBPD as off-road fuels and industrial fu-els,1.65MBPD as jet fuel,0.93MBPD as residualC.Song/Catalysis Today86(2003)211–263213 Table3Average properties of crude oils reﬁned in the US during1981–2001and US and world petroleum consumption during1981–2001 Property Year198119912001 Total amounts of crude oils reﬁned in US(million barrel/day)12.4713.3015.13 Average sulfur content of crude oils reﬁned in US(wt.%based on sulfur)0.89 1.13 1.42 API gravity of crude oils reﬁned in US(◦API)33.7431.6430.49 Total petroleum products supplied in the US including importedcrude and products(million barrel/day)16.0616.7119.59 Total worldwide petroleum consumption(million barrel/day)60.9066.7277.12fuel oil,and1.13MBPD as liqueﬁed petroleum gas (LPG),and3.47MBPD for other uses in the US[10]. The problem of deep removal of sulfur has become more serious due to the lower and lower limit of sul-fur content inﬁnished gasoline and diesel fuel prod-ucts by regulatory speciﬁcations,and the higher and higher sulfur contents in the crude oils.A survey of the data on crude oil sulfur content and API grav-ity for the past two decades reveals a trend that US reﬁning crude slates continue towards higher sulfur contents and heavier feeds.The average sulfur con-tents of all the crude oils reﬁned in theﬁve regions of the US known asﬁve Petroleum Administration for Defense Districts(PADDs)increased from0.89wt.% in1981to1.42wt.%in2001,while the correspond-ing API gravity decreased from33.74◦API in1981to 30.49◦API in2001[12–14].In the past two decades, average sulfur contents in crude oils reﬁned in the US increased by265ppm/year and API gravity decreased by0.16◦API/year,while the total crude oil reﬁned in the US reﬁneries increased from12.47MBPD in1981 (11.20MBPD in1971)to15.13MBPD in2001[10]. The crude oils reﬁned in the US tend to have higher sulfur contents than those in the Western Europe.For example,the average crude oil feeds to US reﬁneries in2000have1.35wt.%sulfur and31.0◦API gravity, whereas European reﬁnery feed by comparison was sweeter at1wt.%sulfur and35◦API gravity[15]. The total world consumption of reﬁned petroleum product in2000was76.896MBPD,in which the con-sumptions in the US and western Europe were19.701 and14.702MBPD,respectively.The problem for diesel desulfurization is also somewhat more serious in the US because a higher proportion of light cycle oil(LCO)from FCC is used in the diesel pool in the US,which has higher contents of more refractory sulfur compounds(see below).H2demand increase is another challenge to the reﬁnery operations.Hydro-gen deﬁcits are processing restraints and will impact future hydrotreating capabilities and decisions[16].2.Reactivity of organic sulfur compounds in hydrodesulfurization(HDS)Fig.1presents a qualitative relationship between the type and size of sulfur molecules in various distil-late fuel fractions and their relative reactivities[17]. Various reﬁnery streams are used to produce three major types of transportation fuels,gasoline,jet fuels and diesel fuels that differ in composition and proper-ties.The common types of sulfur compounds in liquid fuels are outlined in Table4,which corresponds to Fig.1for transportation fuels.The reactivity ranking in Fig.1is based on well-known experimental obser-vations and a large amount of literature information [18–21].For the sulfur compounds without a conju-gation structure between the lone pairs on S atom and the␲-electrons on aromatic ring,including disulﬁdes, sulﬁdes,thiols,and tetrahydrothiophene,HDS occurs directly through hydrogenolysis pathway.These sul-fur compounds exhibit higher HDS reactivity than that of thiophene by an order of magnitude[22],be-cause they have higher the electron density on the S atom and weaker C–S bond.The reactivities of the 1-to3-ring sulfur compounds decrease in the order thiophenes>benzothiophenes>dibenzothiophenes [23–27].In naphtha,thiophene is so much less re-active than the thiols,sulﬁdes,and disulﬁdes that the latter can be considered to be virtually in-ﬁnitely reactive in practical high-conversion pro-cesses[22,28].Similarly,in gas oils,the reactivities214 C.Song/Catalysis Today86(2003)211–263Fig.1.Reactivity of various organic sulfur compounds in HDS versus their ring sizes and positions of alkyl substitutions on the ring[17]. of(alkyl-substituted)4-methyldibenzothiophene and4,6-dimethyldibenzothiophene(4,6-DMDBT)aremuch lower than those of other sulfur-containingcompounds[28–31].Consequently,in deep HDS,the conversion of these key substituted dibenzothio-phenes largely determines the required conditions.Gates and Topsoe[28]pointed out in1997that4-methyldibenzothiophene and4,6-DMDBT are themost appropriate compounds for investigations ofcandidate catalysts and reaction mechanisms.Fig.2shows the sulfur compounds in theﬁnishedproducts of gasoline,jet fuel,and diesel fuel that arerepresentative of current commercial transportation fu-els in the US[32,33].It can be seen that in each ofthe fuels,what are left as sulfur compounds in theﬁn-ished products are those that have lower reactivitiesamong all the sulfur compounds in the correspondingfeed shown in Fig.1,e.g.,naphtha range for gasoline,kerosene range for jet fuel,and gas oil range for dieselfuel.Deep desulfurization and ultra-deep desulfuriza-C.Song /Catalysis Today 86(2003)211–263215Table 4Typical sulfur compounds and corresponding reﬁnery streams for fuels Sulfur compoundsReﬁnery streamsCorresponding fuelsMercaptanes,RSH;sulﬁdes,R 2S;disulﬁdes,RSSR;thiophene (T)and its alkylated derivatives,benzothiopheneSR-naphtha;FCC naphtha;coker naphthaGasoline (BP range:25–225◦C)Mercaptanes,RSH;benzothiophene (BT),alkylated benzothiophenesKerosene;heavy naphtha;middle distillateJet fuel (BP range:130–300◦C)Alkylated benzothiophenes;dibenzothiophene (DBT);alkylated dibenzothiophenesMiddle distillate;FCC LCO;coker gas oilDiesel fuel (BP range:160–380◦C)Greater than or equal to three-ring polycyclic sulfur compounds,including DBT,benzonaphthothiophene (BNT),phenanthro[4,5-b,c,d]thiophene (PT)and their alkylated derivatives and naphthothiophenes (NT)Heavy gas oils;vacuum gas oil;distillation residesFuel oils (non-road fuel and heavyoils)Fig.2.Sulfur compounds in commercial gasoline,jet fuel and diesel fuel identiﬁed by GC-FPD analysis coupled with GC-MS and reaction kinetic analysis [32].216 C.Song/Catalysis Today86(2003)211–263tion refers to processes to remove sulfur(that exists in current gasoline and diesel fuels as shown in Fig.2)to below15ppmw for diesel fuels and to below30ppmw for gasoline,respectively.3.Catalysts for hydrotreating/HDS3.1.Catalyst formulationsThe formulations of modern hydroprocessing cata-lysts originated from early research in catalytic coal liquefaction and coal liquids upgrading to automo-tive fuels in the1920s and the1930s in Germany which led to catalysts based on molybdenum and tung-sten with nickel or cobalt promoters[34–36].The basic compositions of current hydrotreating catalysts are represented by molybdenum sulﬁde promoted by cobalt or nickel and supported on porous␥-alumina, Co–Mo/Al2O3,Ni–Mo/Al2O3,with various modiﬁca-tions by using additives(e.g.,boron or phosphorus or silica)or more promoters(e.g.,Ni–Co–Mo/Al2O3)or improved preparation methods.The activity and se-lectivity of the hydrotreating catalysts have been im-proved signiﬁcantly as a result of continuous research and development in research institutions and catalysts, and petroleum companies worldwide.An excellent review has been published by Topsoe et al.[37]on chemistry and catalysis by metal sul-ﬁdes.Design approaches for developing more active catalysts are based on the ideas to tailor the active sites for desired reactions.The exact nature of ac-tive sites in Co–Mo or Ni–Mo catalysts is still a sub-ject of debate,but the Co–Mo–S model(or Ni–Mo–S model for Ni–Mo catalysts)is currently the one most widely accepted[37,38].According to the model,the Co–Mo–S structure or Ni–Mo–S structure is respon-sible for the catalytic activity of the Co-promoted or Ni-promoted MoS2catalyst,although the model does not specify whether the catalytic activity arises from Mo promoted by Co or from cobalt promoted by molybdenum.Density-functional theory(DFT)calcu-lations show that addition of Co–MoS2structure low-ers the sulfur binding energy at the edges and thereby provides more active sites[39].Recently,the forma-tion of sulfur vacancy in MoS2under H2atmosphere has been observed directly for theﬁrst time by scan-ning tunneling microscope(STM)[40].Comparison of STM images for Mo sulﬁde-based particles with and without cobalt promoter atoms shows that with-out cobalt,the MoS2particles assume a neat triangu-lar shape.Once cobalt enters the crystals,the particles become truncated hexagons–triangles with clipped-off vertices[41].These newﬁndings from experimental STM observations are consistent also with the FT-IR studies for NO chemisorption on Co–Mo catalysts. Co–Mo catalysts with more Co sites exposed(Co edge sites)tend to have higher activity for HDS[37],and this trend has been observed also for Co–Mo/MCM-41 and Co–Mo/Al2O3catalysts based on DBT HDS and FT-IR of chemisorbed NO[20].Among the Co–Mo–S structures for alumina-supported catalysts,the intrinsically more active phase was referred to as type II(Co–Mo–S II),and the less active phase as type I(Co–Mo–S I);type I structure is assumed to be bonded to support through Mo–O–Al linkages and has less stacking,whereas type II struc-ture has higher stacking and few linkages with support [38].For steric reasons,catalyst–support linkages in Co–Mo–S I probably hinder reactant molecules from approaching the catalytically active sites,and thus Co–Mo–S II is more active than Co–Mo–S I although Mossbauer and EXAFS signals of types I and II structures are the same.Daage and Chianelli [42]reported that the top and bottom layers(rim)of unsupported MoS2stacks(slabs)have a much higher activity than the surface of intermediate layers(edge) for hydrogenation of DBT,while the hydrogenolysis of the C–S bond in DBT occurs equally well on all MoS2layers.They proposed a rim-edge model,and explained that theﬂat␲-adsorption on MoS2surface results in hydrogenation of DBT which can take place on rim sites but this adsorption is more difﬁcult on edge sites,whereas vertical adsorption of sulfur is as-sumed to be necessary for C–S bond hydrogenolysis which can take place on surface Mo sites of all layers (both rim and edge).The Co–Mo–S model makes no distinction between rim and edge,but Co–Mo–S II would seem to have relatively more rim sites that are not likely to be inﬂuenced by steric hindrance of reactant adsorption.Consequently,more Co–Mo–S II structures can lead to more active catalysts for desulfurization of polycyclic sulfur compounds. Table5shows typical hydroprocessing conditions used in industry[43].The choice of commercial hy-drotreating catalysts,represented by Co–Mo,Ni–MoC.Song /Catalysis Today 86(2003)211–263217Table 5Typical hydroprocessing conditions used in industry [43]Fuel type and historical conditionsPressure (MPa)LHSV (h −1)Temperature (◦C)Recent historyNaphtha (gasoline) 1.38–3.452–8290–370Kerosene/gas oil (jet/diesel fuels) 3.45–8.272–4315–400FCC feed pretreat 5.17–13.80 1.0–3.0370–425Current trendsNaphtha (gasoline) 1.38–5.172–6290–370Kerosene/gas oil (jet/diesel fuels) 3.45–10.300.5–3.0315–400FCC feed pretreat6.90–20.700.5–2.0370–425and Ni–Co–Mo usually supported on alumina with or without modiﬁers,depends also on the capability of reactor equipments,operating conditions (pressure,temperature),feedstock type and sulfur contents,and desired level of sulfur reduction.Increasingly more se-vere conditions and more active catalysts are used to-day for hydroprocessing.In general,for low-pressure and high-temperature desulfurization of distillate fuels,Co–Mo catalysts may be better than Ni–Mo catalysts.For high-pressure and low-temperature con-ditions,Ni–Mo catalysts perform better than Co–Mo catalysts.Ni–Mo catalysts generally have higher hy-Table 6Worldwide reﬁnery catalysts markets [44–46]CategoryYear 1992[46]1997[44]2001[44,45]2005[45]Total catalyst marketUS$7.40billion [47]US$10.16billion Total reﬁnery catalyst market US$2.2billion US$2.07billion US$2.32billion US$2.68billion By sector in reﬁneryHydrotreating/desulfurization US$265million (12%)US$723million (34%)US$789million (34%)US$965million (36%)Catalytic cracking/FCC US$900million (41%)US$944million (45%)US$696million (30%)US$804million (30%)Naphtha reforming US$90million (4%)US$124million (6%)US$139million (6%)US$134million (5%)Hydrocracking US$200million (9%)US$155million (7%)US$116million (5%)US$134million (5%)Others a 34%US$125million(6%)US$580million(25%)US$643million(24%)By region for reﬁnery North America (%)4038Western Europe (%)2019Asia/Paciﬁc (%)1920Rest of world (%)b2123a Include isomerization,alkylation,etheriﬁcation,polymerization,lubes,sulfur recovery,hydrogen,and puriﬁcation catalysts.bIncludes Eastern Europe,Mid-East,and South America.drogenating ability than Co–Mo counterparts,and higher H 2pressure and lower temperature favor the hydrogenation reactions and thus facilitate HDS by hydrogenation pathway.The trimetallic Ni–Co–Mo catalysts can combine the features of Co–Mo and Ni–Mo,and this new formulation feature is being used in some recent commercial catalysts.3.2.Global catalyst marketsTable 6shows the global merchant reﬁnery catalyst market distribution during 1997–2001with a projec-tion to 2005[44–47],together with the data for 1992[46]for comparison.The largest volume gain in re-ﬁning catalysts was in hydrotreating/HDS catalysts.In fact,HDS catalysts recently overtook FCC as the largest market for reﬁnery catalyst makers.HDS cata-lysts are playing an increasingly more important role in reﬁneries today for producing clean fuels that meet the regulatory sulfur requirements.A 1999report puts the 1997global merchant catalyst market at US$7.4billion,with the following distribution:28%reﬁnery,27%chemical,23%polymerization,and 22%envi-ronmental,in which the environmental part excludes the value of the precious metals and substrate used and includes only manufacturing fees [47].According to a study reported in 2000,the global merchant catalyst218 C.Song /Catalysis Today 86(2003)211–263market is about US$10billion/year,with the captive market worth an additional US$2billion to US$3billion and total market growth approaching 10%per year [48].It is clear from these studies that reﬁning catalysts,particularly desulfurization catalysts,repre-sent an important category of growth areas due to the needs for producing cleaner transportation fuels.In addition,some new approaches and new technologies that do not use hydrotreating are also emerging in the past several years [17,21,49].4.Deep desulfurization of naphtha for ultra-clean gasoline4.1.Gasoline pool and sources of sulfurTable 7shows the typical gasoline pool composi-tions in the US [50]and in the western Europe [51].It is well known that naphtha from FCC makes up about 25–40%(average of 36%in the US)of gasoline blend stocks,but accounts for over 90%of the sulfur (up to 90–98%)and essentially all of the oleﬁns in the entire gasoline pool.Therefore,the key to deep desulfuriza-tion of gasoline is sulfur removal from FCC naphtha.It is well known that sulfur removal from FCC naph-tha can be achieved by catalytic HDS,but the accom-panying decrease of octane number is a signiﬁcant loss due to the saturation of oleﬁns.Fig.3shows the re-lationship between HDS and octane loss for conven-tional hydrotreating,in which the plot is made based on data from industrial sources [52].Because FCC naphtha also has a high content of oleﬁns (e.g.,20%)Table 7Typical gasoline pool composition in US and western Europe Gasoline blend stocks Percentage of gasoline pool volume in US Percentage of gasoline pool sulfur in US Percentage of gasoline pool volume in western Europe FCC naphtha369827Naphtha reformate 34–40Alkylate12–9Light straight-run naphtha 317.5Coker naphtha11∼0Hydrocracked naphtha 2–∼0Isomerate 5–10Butanes 5– 5.5MTBE 2– 1.0Total (%)100100100which have higher octane number,selective sulfur re-moval without loss of octane number (or without loss of oleﬁns)is desirable.Hydrotreating of FCC naphtha is an attractive process alternative,provided that oc-tane losses are minimized by either minimizing oleﬁn saturation during HDS or restoring the octane number after the HDS.FCC naphtha can be divided (in a fractionator or splitter)into light cat naphtha (LCN,IBP:140◦F or 60◦C),medium (or intermediate)cat naphtha (MCN or ICN)cut,and heavy cat naphtha (HCN)cuts.To-tally debutanized FCC naphtha distills between 80and 430◦F (27–221◦C)boiling range [53].A MCN or ICN cut is deﬁned by an initial boiling point that should in-clude thiophene (183◦F,85◦C)but thiophene begins to distill with C6hydrocarbons boiling above 140◦F (60◦C)and below 200◦F (93◦C)which makes the better fractionation more important for MCN [53].The ﬁnal boiling point of MCN is ﬂexible between 270and 360◦F (132and 182◦C)[54].Sulfur species change from primarily mercaptans in the low boiling IBP:140◦F (60◦C)LCN to thio-phenes and substituted thiophenic sulfur compounds in 140–390◦F (MCN +HCN ),and benzothiophenes and substituted benzothiophenes in the 390–430◦F (bot-tom part of HCN).Above 390◦F (199◦C),total sulfur increases rapidly with boiling point [53].In general,LCN has most of the oleﬁns and the sulfur in mercap-tan form;caustic treatment is used for LCN treatment to remove mercaptans.Thiophene cannot be extracted by caustic treatment and that is why fractionation of FCC naphtha is important.HCN contains much less oleﬁns and most of the thiophenic sulfur,and thusC.Song /Catalysis Today 86(2003)211–26321910152025303540455010100100010000Sulfur level, ppmO l e f i n c o n t e n t , %10100100010000Sulfur level, ppmR O N (G C )Fig.3.Relationship between desulfurization and oleﬁn content (top)and octane number of FCC naphtha (plot by Ma et al.based on data from Desai et al.[52]).can be desulfurized in a hydrotreater.MCN or ICN is the lowest-octane portion of FCC naphtha,and can be desulfurized deeply to produce a blend stock or re-former feedstock [54].4.2.Approaches to gasoline sulfur removal Table 8outlines the catalytic and non-catalytic ap-proaches to gasoline deep desulfurization with general remarks on their features based on published infor-mation in the open literature [17,55–57].Approaches to reducing sulfur content in FCC naphtha include:(1)post-treating product to remove sulfur from FCC naphtha [55,56];(2)pretreating the FCC feed to re-move sulfur [50];(3)increasing sulfur conversion in situ to hydrogen sulﬁde during the FCC operation [56].The principles of these methods are based on one or more of the following processes:catalytic HDS,selective HDS,reactive adsorption using solid sorbent and H 2at elevated temperature,selective adsorption without using H 2at ambient temperature,distilla-tion or extraction coupled with HDS,membrane,and220 C.Song/Catalysis Today86(2003)211–263Table8Approaches to deep desulfurization of naphtha for cleaner gasolineCategory Description and representative process Remarks(I)Post-FCC sulfur removal Conventional HDS process without special oleﬁnpreservation(many companies)HDSConvert organic sulfur to H2S by selective HDS whilepreserving oleﬁns(ExxonMobil’s SCANﬁning;IFPPrime G+)Selective HDSHydrodesulfurize organic sulfur,saturate oleﬁns butconvert parafﬁns for octane gain(ExxonMobilOCTGain125;UOP-INTEVEP’s ISAL)HDS plus octane recoveryReactive adsorption and capture of sulfur by solid adsorbent at elevated temperatures under low H2 pressure(Phillips Petroleum S-Zorb Gasoline)Non-HDS;stoichiometric H2 consumptionSulfur adsorption and capture by solid metal oxideadsorbent at high temperatures(RTI TReND)Non-HDS;use H2atmospherePolar adsorption by using solid adsorbent based onalumina(Black and Veatch Prichard IRV AD)Polar adsorptionSelective adsorption for removing sulfur(SARS)as organic compounds by solid adsorbent at ambient temperature without using H2(Pennsylvania State University,PSU-SARS)S adsorption,no H2;can reach<1ppm S for fuel cellsIntegrated adsorption and hydrotreating ofconcentrated sulfur from adsorption(PennsylvaniaState University,PSU-SARS-HDSCS)S adsorption coupled with HDSDrop the organic sulfur to heavier fraction byalkylation of thiophenes(BPs OATS process)Alkylation and boiling point shiftRemove the organic sulfur by using caustic treatment (Merichem’s THIOLEX/REGEN process;Exomer by Merichem and ExxonMobil)or extraction(GTC Technology’s GT-DeSulf)Extraction of sulfur in light fraction of naphthaRemove the organic sulfur by using membraneﬁltration(Grace’s S-Brane TM Process)Membrane separation of light naphtha(II)Pre-FCC sulfur removal Deep HDS of feed before catalytic cracking in FCCreactor,which greatly reduces sulfur in FCC naphthaand in LCO(Akzo Nobel,IFP,UOP,etc.)HDS at higher H2pressurePhysico-chemical treatment such as adsorption orextraction to remove sulfur(concept suggested here asa possible approach based on PSU-SARS)Adsorption without H2(III)In situ FCC sulfur removal Convert more organic sulfur into H2S during FCCoperation,which can reduce organic sulfur in liquidproducts(Akzo Nobel’s Resolve;Grace Davison’sSaturn(GSR-6.1))Sulfur conversion in FCCCapture organic sulfur using metal species to retainsulfur as sulfur oxide,and regenerate it in theregenerator(concept suggested here as a possibleapproach based on reactive adsorption using sorbent)Sulfur capture in FCC。

不可知的真实抑或不可交流的真实

不可知的真实抑或不可交流的真实【摘要】本文以意大利新现实主义电影《放大》为例，探讨了该类电影往往具有的丰富的哲学、心理学、社会学、政治学意义。

认为该类作品提倡内心的写实主义，关注人的精神状态的病态和异化，关注人际关系。

指出在《放大》中，人与人之间是不可交流而感到疏离的，造成这一点的重要因素便是其中人们看待事物的真实价值方式，即表象的真实高于现实的真实。

【关键词】意大利；新现实主义电影；不可交流；真实米开朗基罗·安东尼奥尼（1912.9.29-2007.7.30）是意大利新现实主义电影流派后期的代表性人物，主要作品有“人类感情三部曲”：《奇遇》、《夜》、《蚀》；《红色沙漠》、《放大》、《云上的日子》。

他的作品提倡内心的写实主义，关注人的精神状态的病态和异化，关注人际关系。

“我只关心人”。

这是他的名言。

他一直将影片的重点放在人物的内心世界，简化甚至舍弃叙事和戏剧冲突，他的电影很少有传统意义上的跌宕起伏、环环相扣的情节故事，不以戏剧性的冲突来构造情节。

纵观他的影片，他似乎主要关心个人试图与他人交流而又感到人与人之间不可交流的疏离主题。

往往用全知视角的无聚焦和主视角的内聚焦精巧结合的方式，来全面体现主人公的外在感知及其内心属性中的映射。

他的影片的成功之处，并不在于彰显了现实问题的答案，而是在于将问题交给观众，使得不同视角、不同背景的观众对问题产生符合各自认知的思考。

安东尼奥尼是“作者电影”的开创者，这类电影往往具有丰富的哲学、心理学、社会学、政治学意义。

《放大》就是这样一部典型“作者电影”。

与任何一部安东尼奥尼的电影作品一样，《放大》是一部令人迷惑的电影，影片并没有一条明显的叙事线。

在主人公托马斯到公园拍下照片的情节开始之前，街道上、摄影棚里发生的混乱的事件和琐屑视角让人无法看出影片的表述意图，随后，突然发生的、和之前情节没有直接联系的公园案件才貌似推动主要情节的展开。

影片随即由外在视角转入托马斯的内部视角，他不断试图探寻案件的真相。

从目的论看米欧敏英译《解密》

从目的论看米欧敏英译《解密》作者：郑玮博来源：《校园英语》 2019年第22期文/郑玮博【摘要】全球化的进步离不开经济发展，同时也离不开文化的交流。

因此，如何传播发扬中国文化，使中国文化易于被外界所接受，就成了一大难题，而好的翻译正是解决这一问题的钥匙。

译文是否能为受众所接受和认可在很大程度上决定了翻译方法和翻译策略的选择应以目的为导向。

本文将以米欧敏英译《解密》为例，从翻译目的论的视角，以目的论三大原则为基础，分析《解密》英译本的成功原因，为日后将中国作品推向世界作参考。

【关键词】目的论翻译；目的原则；连贯性原则；忠实性原则；作者意图【作者简介】郑玮博，天津大学外国语言与文学学院。

一、目的论翻译概述翻译目的论兴起于二十世纪七十年代，由德国学者费米尔在行动理论的基础上提出，并成为了功能派翻译理论的核心理论。

目的论强调的是译者应该以翻译的最终目的为主线，并依据这条主线采取合适的翻译方法和策略。

因此，从目的论的角度看，翻译方法和策略的选择应由翻译目的决定，决定的过程应遵循目的论三大原则，即目的原则、连贯性原则、忠实性原则。

二、《解密》及其英译《解密》英文版在全球范围内的成功与其译者和译介模式是分不开的。

《解密》英文版的第一译者米欧敏是一位古汉语学者，她米欧敏谈道，翻译《解密》是一件很偶然的事。

在机场转机时，她在书店看到了《解密》这本书，由于米欧敏的爷爷曾和著名破译专家阿兰·图灵共事过，她对麦家的谍战小说产生了非常浓厚的兴趣，并想把该书翻译出来给爷爷阅读。

可以说，米欧敏翻译《解密》的初衷，一部分是源于自身的兴趣，还有一部分是为迎合读者，即她的爷爷。

米欧敏认为，自己翻译的目标，就是“让读者觉得是麦家在用英文说故事”。

而《解密》英文版在英语国家的广受好评，则证明了米欧敏的成功。

三、从目的论视角看《解密》英译在翻译过程中，米欧敏没有局限于一种翻译策略，而是为了读者的阅读兴趣和阅读质量，将归化和异化相结合，直译与意译相结合，在忠实原文的前提下，又对原文中的隐喻、文化负载词做了灵活的处理。

Melitz2003年奠基之作-中文翻译

贸易对产业内重新配置和产业总生产率的影响（The Impact of Trade On Intra-industry Reallocations and Aggregate Industry Productivity）Melitz, Marc(2003)，Econometrica; Nov 2003; 71, 6浙江财经大学经济与国际贸易学院茹玉骢翻译\推导并注释摘要：本文发展了一个异质性产业动态模型，分析国际贸易的产业内作用。

模型显示如何开展贸易，会导致更有生产率的企业进入出口市场（同时，一些生产率比较低的企业只在国内市场进行生产），并同时迫使最没有生产率的企业退出市场。

它还表明产业的贸易开放会导致向更有生产率企业的公司之间额外的重新配置。

文章也表明，通过重新配置所导致的产业总生产率的提高带来了福利的改进，从而揭示了以前从未探讨的贸易益处。

本文把Hopenhayn（1992）的动态产业模型结合垄断竞争，在一般均衡中加以讨论。

因此，文章结合生产率的差异，拓展了Krugman1980的贸易模型。

不同生产率的企业共存于一个产业是因为，每个企业在做不可逆转投资进入该产业之前，面临不确的初始生产率。

进入出口市场也是颇费成本，但企业仅在获得其生产率知识后做出出口决定。

1、引言最近的经验研究表明企业之间的生产率存在持续性的差异，另外一些研究也表明生产率高的企业通常会倾向于出口。

文章发展了一个异质性动态产业模型，用来分析国际贸易所祈祷了产业内企业之间配置催化剂作用。

模型重复了许多与贸易相关的微观研究，它显示贸易如何导致那些生产率更高的企业出口，而同时迫使生产率最低的企业退出。

效率最低企业的退出和更有效率企业获得额外出口销售，使得市场份额更趋向于生产率更高的企业，并导致总生产率的提高。

利润也分配给更有生产率的企业。

模型和许多经验研究相吻合，如Bernard and Jensen(1999a)(对美国), Aw, Chung and Roberts(2000)(对台湾),Clerides, Lack and Tybout(1998)（对哥伦比亚、墨西哥和摩洛哥）都, 发现了更有效率企业选择出口市场的证据。

从意义到实效：皮尔斯的实效主义哲学

・外国哲学・从意义到实效:皮尔斯的实效主义哲学柯　华　庆实效主义(Prag maticis m )属皮尔斯首创。

皮尔斯英文版8卷本文集的第5卷以《实用主义与实效主义》(P ragm atis m and P ragm aticis m )命名。

然而,“实用主义”(Prag matis m )概念通过詹姆斯著名的《实用主义》一书得到流行,“实效主义”概念却鲜有学者提及,甚至皮尔斯自己也一直没有明确区分这两个概念。

那么,皮尔斯究竟为什么要提出实效主义概念?他的实效主义与詹姆斯的实用主义之间有何区别与联系?本文试图通过考察皮尔斯与詹姆斯、席勒和杜威等人的哲学之间的关系,解释以上问题,进而完整把握或者说重构“实效主义”的哲学内涵。

一、实效主义的家族类似皮尔斯在《什么是实用主义?》一文中用“实效主义”区别他的哲学与被滥用的“实用主义”之间的不同。

皮尔斯最初确实是用“实用主义”来表达他的哲学的,而且他取名“实用主义”时是经过深思熟虑的:“对于这种学说,我想出‘实用主义’这个名称。

……而‘实用’则表达了与人的特定目标的联系。

这种崭新的理论的最为令人瞩目的特征,正在于它确认在理性认识和理性目的之间有着不可分割的联系。

正是这种考虑决定了我对‘实用主义’这个名称的偏爱。

”(《皮尔斯文选》,第4-5页)也就是说,皮尔斯强调“实用”以表达他的哲学与人类的特定目标的联系。

那么,皮尔斯为什么要重新正名呢?这是因为随着“实用主义”这个用语“普遍地见诸于文学报刊,它在那里遭到在文字游戏中那种无可幸免的恣意歪曲。

……目前,拿这个词来开美国哲学的玩笑,这已成为英国人的一种时尚”。

所以,为了扼要表述其学说的本义,皮尔斯宣布采取一个新的名称:“实效主义”。

(同上,第7页)实际上,当一个哲学体系被冠之以“某某主义”时,它被大众误解是不可避免的,问题在于皮尔斯实效主义哲学是不是被詹姆斯、席勒、杜威等哲学家所误解了。

皮尔斯最初提出的是一种实用主义的意义理论,而詹姆斯的实用主义把皮尔斯的意义理论转变为真理理论,席勒的人本主义强调一切意义都以人的目的为依据(参见同上,第62-63页),杜威则秉承皮尔斯传统,注重方法论方面,他不满意詹姆斯和席勒等人太注重个体事物和意志的方面,所以杜威自称为“工具主义”(有时又称为实验主义或试验主义)。

《I型起源》解说文案_科学与宗教的证明

《I型起源》解说文案_科学与宗教的证明美国剧情/科幻电影《I型起源》，于2014年上映，由迈克·卡希尔导演，迈克·卡希尔编剧，影片讲述了伊恩·格雷，分子生物学在读博士，专攻眼睛的进化。

他离开实验室去参加了一个聚会，在那里他邂逅了一位神秘的带着面具的模特女郎，虽然只是转瞬即逝的一瞬间，之后她就是消失在黑夜中。

凭着记忆里女孩美丽动人的眼睛，他找到了她，两人陷入爱河。

即使两个人对于生活的基本信仰完全不同，但这只会加深他们之间的联系，他们立誓永远陪伴彼此。

多年后，伊恩和他的实验搭档凯伦有了一次具有深远意义的发现。

现在他必须要离开家人，穿越世界各地去找寻这项新发现的真实和意义。

、。

轮回意味着一种神迹，当相同的生命密码在不同的生命体上得到重现，神的力量被印证，这大概就是《I型起源》的核心主题。

生物学家伊恩是个无神论者，他试图通过分析眼睛的进化来论证生物的进化都是自然的选择，而并非神的旨意。

但突然，他发现一个远在印度的小女孩竟然拥有与他去世前女友一模一样的眼睛，相同的虹膜纹路，隐藏的莫名记忆，都在向他证明转世的存在。

超自然的神秘力量冲击了他对科学的信仰，他开始疑惑，世界的终极哲学到底是科学还是宗教。

我并不认同伊恩的逻辑，轮回的存在也不一定能够证明神的存在，因为没有谁敢保证，轮回就是神拟定的规则，且神的定义本身就含糊不清。

尽管作为工科生的我，对某些细节的逻辑还依然纠结，但我确实相信轮回的存在；我也相信神明，不是那种呼风唤雨的神仙，而是悟道超脱的至高智慧。

从科学的角度去解读，轮回或许只是一种基因的传承和复制，是一种很平常的生命现象。

数百年的祖先印记，像一组组信息编码附着在一段段ＤＮＡ内，隐藏在每个女子的卵子和每个男子的精子中，在每一颗受精卵的发育过程中，来自两个家族的基因信息相互融合，重组成一个新的生命螺旋。

这个生命自诞生之日起，就携带着祖先的生命特征和祖先的记忆，这种传承本身就可以说是一种轮回，只不过我们或许片面地理解了轮回的含义。

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Prototypic Realisation of Millimetre Wave Radar Imaging R. Schneider, J. Wenger, DaimlerChrysler AGAbstractIn future novel driver assistance, comfort, and safety systems the needs for environmental sensing and traffic scene interpretation are increasing. The reliability of these systems will be mainly deter-mined by the perception of the sensors and the capability of auto-matic data interpretation, and it will be a differentiating factor in the competition amongst automotive OEMs. Automotive radar is expect-ed to be a key sensor technology for future active safety systems,especially due to its specific physical properties (direct acquisition of range and velocity). This contribution demonstrates the potential of radar sensors with high resolution in azimuth and range in traffic environment and addresses some aspects of their practical imple-mentation. A prototype of an automotive instrumentation radar is presented, which allows on-line acquisition and real-time visualisa-tion of radar images with an update rate of up to 10Hz. The imaging capabilities of high resolution radar in traffic environment will be pointed out with respect to new comfort and safety features. In addi-tion practical realisation approaches will be discussed.1Current Status of Automotive RadarIn 1999 Mercedes-Benz has been the first to introduce a millimetre-wave radar for autonomous cruise control (ACC) and radar has proven to be an ideal sen-sor in traffic environment [1]. Meanwhile some car manufacturers like Jaguar,BMW , or Volkswagen in the new Phaeton offer ACC for highway operation as an option, others plan to do this in the near future. Further development activ-ities of the suppliers are primarily focused on reducing costs and size of the sensor. Although announced on their roadmaps, no additional functionality beyond ACC, like stop-and-go support, obstacle detection, and collision avoid-ance seems to be in sight for mass products, as this would require clearly enhanced sensor capabilities. Due to the moderate resolution of the employed sensors, insufficient information about the environment is delivered in order to enable advanced driver assistance functions like reliable obstacle warning or emergency breaking.97A conventional ACC radar sensor delivers a target list with distance, azimuthangular position, relative speed, and reflectivity of significant objects, which typically are smaller than the spatial resolution of the radar. Hence a classifi-cation of these point-targets generally is not possible. T able 1 lists some char-acteristics of an ACC radar sensor (Distronic by Mercedes-Benz). In current ACC systems the handling of stationary targets is difficult, as they cannot be separated by differences in their Doppler-shift.T ab. 1.System parameters of a typical ACC radar sensor.2Specific Properties and Potential of Millimetre-Wave Radar Imaging The use of a multi- or scanning-beam radar with high resolution in range and azimuth, which generates real-aperture radar images containing considerably more information about the ambient traffic situation, could overcome the missing capability of object classification and scenario interpretation in first generation ACC sensors. At the DaimlerChrysler Research Centre in Ulm the fundamental potential of high resolution mm-wave radar with respect to auto-motive applications has been investigated since several years [2-4]. One of the most important results was that vehicles appear as laterally and longitudinal-ly extended objects in high resolution radar images in range versus azimuth.Caused by reflections from the road surface, the complete two-dimensional extension of bottom sides is perceived, allowing for the recognition of vehicles and distinction of different classes (cars, vans, trucks) [5]. Even obscured road users become visible, which provides very important information for the oper-ation in stop-and-go traffic. Another benefit is that road environment like any kind of vegetation and man-made ground structures (slopes, guard rails, reflec-tion posts, traffic signs, etc.) can clearly be detected, enabling recognition and prediction of the road course.Safety98As the essential information about the environment is contained in a radar image with the spatial co-ordinates azimuth and range, no resolution in eleva-tion and no large vertical antenna aperture is required. The corresponding line antenna would be well compatible with the vehicle front design and space requirements.A crucial advantage of radar sensing is its direct acquisition of speed viaDoppler processing, which could be taken as a third dimension in the radar images. Effective data compression is achieved by reducing the velocity infor-mation of an azimuth-range resolution cell just to a single value representing the dominant reflection object in this cell. The resulting information is described in two 2D image matrices of radar reflectivity and Doppler. For visu-alisation purposes both matrices can be combined into a single image using a pseudo-colour coding of Doppler and radar intensity into hue and saturation,for example.Fig. 1.T raffic scene and corresponding high resolution radar image in PPIrepresentation.Figure 1 shows an example of such a kind of radar image and exhibits the spe-cific properties of high resolution radar sensing at millimetre waves in traffic environment. The colour coding of relative Doppler shift is: yellow for the same speed, red and green for closing and opening Doppler, respectively.The spatial radar data acquired in polar co-ordinate grid has been transformed into a Cartesian PPI (planar position indicator) representation in range and 99cross-range, which delivers a geometrically correct bird's eye view of thescene. The camera for video documentation was located close to the antenna position 60cm above ground. Radar acquisition parameters as listed in table 2have been set. Details about the radar set-up will be discussed in the following sections.Figure 1 clearly depicts the left roadside with guard rail, which approaches while driving and appears as a red line. Although the right roadside is merely covered with grass, it can be recognised. The preceding truck with trailer appears yellow due to its zero relative Doppler shift, and as an extended area with true dimensions as a result from the road surface reflections. Even a car in front of the truck becomes visible by the wave duct effect. Its green colour indicates an increasing distance from the truck.Here a very attractive feature becomes evident: In platoon traffic not only the next vehicle can be tracked but also at least another one ahead. Perceiving its manoeuvres could improve longitudinal vehicle control considerably.T ab. 2.Acquisition parameters for high resolution radar data.3Prototypical Realisation of an Automotive Imaging RadarBased on the fundamental findings about millimetre-wave imaging a prototype of a mobile instrumentation radar system for on-line radar image acquisition and real-time visualisation was specified and realised. Although the overall system design aims at high performance and versatility, its basic features have the perspective of mean to long term commercialisation. Installed in a test car the system serves for the detailed evaluation and demonstration of the capa-bilities of radar imaging, data acquisition, design, and test of processing algo-rithms, and as a basis for the implementation of new comfort or safety appli-cations. Its operation parameters can be varied in wide ranges in order to achieve different image areas, resolution, and sensitivity.Safety1003.1System DesignImaging of vehicle underbodies and detection of hidden objects via reflections from the road surface require higher sensitivity with respect to a convention-al ACC radar sensor. Preliminary investigations resulted in the need of about 20dB additional sensitivity in order to enable these features up to 150m range, as those targets are characterised by radar cross section (RCS) values of down to -20dBsm. An increased target dynamic of 50dB has to be assumed. T ogether with the dynamic of 60dB due to propagation attenuation in 5-150m range an overall requirement for system dynamic results, with certainly cannot be han-dled by a FMCW system. Hence pulsed waveform has been chosen for the imaging radar system design because of its robustness against saturation. The radar transceiver lay-out has been based on practical imaging parameters (see table 2). Range resolution of 1 m corresponds to 7 nsec pulse duration and to 150MHz bandwidth of a matched IF filter. The gain of an antenna with beam widths of 1deg · 5deg is assumed to be at least 38dBi, which contributes considerably to the additionally required sensitivity. Speed resolution in the Doppler processing depends on the number of range bins N and the pulse rep-etition frequency PRF. A practical choice is N = 512 and PRF = 70kHz, which provides sufficient unambiguous speed (50 km/h), unambiguous range (2km), and processing gain (27dB).A minimum signal-to-noise ratio of 10dB should be present in the radar images in order to achieve acceptable detection and false alarm rates. The overall sys-tem losses of radome, front-end, and signal processing are estimated not to exceed 8dB. The transceiver design finally has to find a trade-off between transmit power and receiver noise figure F. Assuming a value of F = 8dB achievable with state-of-the-art balanced Schottky mixers, a transmit power of 19dBm (80mW) would be necessary. As this hardly can be realised with today's MMIC technology, a low-noise receive amplifier (LNA) with a noise fig-ure of 4.5dB was provided to reduce the required transmit (peak) power to a practical value of about 35mW. The resulting mean transmit power is below 20µW.The front-end design should demonstrate a long term potential with respect to producibility (cost aspect), which won't allow for parallel transceiver concepts. This means that the complete field-of-view (FOW) has to be scanned sequen-tially with a single antenna beam, provided that time-on-target requirements can be satisfied. The above-mentioned Doppler acquisition of 512 samples with a PRF of 70kHz delivers full integration gain for a minimum time-on-tar-get of about 7msec. The required FOW is deduced from the demand of opera-tion in urban area or narrow road curvature. Case studies have shown that a 101coverage of ±15deg is fully sufficient, ±10deg is acceptable with restrictionsin urban (crossing) environment. Assuming an azimuth beam-width of 1deg,the maximum achievable image update rate would be (7msec · 30)-1= 4.8Hz in the first and 7.1Hz in the second case. Compared to a video system, the update rate of an imaging radar is allowed to be clearly lower, as the velocity information is directly available and needs not to be derived from differentia-tion of subsequent images. Hence the mentioned update rates are assumed to be sufficient.At the present time the antenna constitutes the technological key component in a real aperture imaging radar. The challenge is to combine fast beam scan-ning of a wide FOW at good electrical properties (efficiency, side-lobes) with the potential of low-cost production, compactness, and mechanical robustness.Phased array concepts fail due to their complexity, focal plane concepts have shortcomings in achieving large FOVs, beam switching leads to high insertion loss in the required switch cascade, and pure mechanical scan isn't practicable for the large aperture.Fig. 2.Schematic diagram (a) and implementation (b) of azimuth scanningfan beam antenna.A very attractive approach, which doesn't completely dispense with moving parts, is a tricky advancement of the image line antenna [6], which exploits the fact that a material inhomogeneity close to a dielectric wave-guide will cause radiation. An equidistant structure (grating) parallel to the wave-guide effects the radiation of a wave-front with a direction depending on the grating peri-od. If now gratings with varying spacing are arranged on the circumference of a drum, sawtooth-wise scanning of the radiated wave-front is achieved by acceleration-free rotation of the drum (see figure 2a) [7]. For beam forming inSafety102the orthogonal (elevation) plane either a cylindrical parabolic reflector ordielectric lens can be used.Figure 2b shows the prototypic implementation of such a 'spinning grating'antenna with lens (design and manufacturing by WaveBand Corp., USA),which was applied for the instrumentation radar set-up. The grating structure is realised by grooves with different pitch in a metallic cylinder resulting in a continuous beam scanning behaviour. A rigid quartz rod of about 1mm diam-eter forms the dielectric wave-guide. A mode launcher allows the antenna to be connected via a standard WR-12 wave-guide flange. The drum driving is performed by a small DC gear motor (which could be integrated into the drum to increase compactness), an angular encoder serves for rotation speed control and exact reference for the beam pointing direction.Practical experience with the antenna proves well applicability in harsh auto-motive environment. Some electrical and mechanical characteristics are com-piled in table 3 (verified by measurements). The azimuth beam-width is some-what larger and accordingly the gain lower than postulated in above system design, but for availability reasons this had to be accepted.T ab. 3.Antenna characteristics.3.2Description of the Hardware and Vehicle InstallationThe instrumentation radar is designed as a versatile test system with real-time processing and visualisation features, which requires an open and universal hardware structure. It consists of a base unit in a standard VME chassis and the remote front-end (transmitter and receiver modules plus antenna). Figure 3 depicts the overall block diagram. The central component is an embedded Pentium III PC with Windows NT performing system controlling, radar image composition and pre-processing, visualisation, and data handling. Its main periphery is formed by timing &control electronics generating all the radar 103timing and a number of direct control signals, an IF processor module for con-verting the IF signal from the receiver (Rx) module into base-band I/Q signals and digitisation, a digital signal processor (DSP) performing the Doppler FFT s and other numerically extensive pre-processing (details see below), and some external standard components.Fig. 3.Block diagram of the complete instrumentation radar system.System operation is done via a graphical user interface (GUI) allowing the adjustment of pertinent radar parameters like transmit pulse width, PRF , IF fil-ter bandwidth, range sampling, number of Doppler bins, and receiver gain.A ferrite circulator for transmit and receive duplex is mounted together with a receive LNA directly at the antenna and connects to the Tx and Rx modules.The transmit signal is generated in a phase locked dielectric resonator oscilla-tor (DRO) at 19.125GHz, pulse gated in a two-stage PIN-modulator, and multi-plied to 76.5GHz in an active quadrupler with an output power of about 16dBm. The minimum pulse length is 3.5nsec. Key component in the Rx mod-ule is a biased, balanced fundamental mixer (measured noise figure F =7.6dB). It converts to an IF signal of 3GHz, which is led to the base system on a high power level in order to minimise interference in the long transmis-sion line.The detailed design and implementation of the VME base system and the Tx/Rx modules as well as programming the control software of the VME com-ponents were performed by Innovative T echnology, USA.Figure 4 shows the integration of the system into a test car. The front-end com-ponents are mounted centred at the front bumper in a weather-proof housing (figure 4a). The antenna height is positioned 60cm above ground, which is a good compromise between exploiting multi-path effects by road surface reflec-tions (hidden cars, vehicle underbodies) and roadside detection. Also with respect to shadowing effects of road crests [5] the antenna position shouldn'tSafety104be to low. The radome is made of 5 mm polypropylene (according to the mul-tiple half-wavelength matching condition) and showed less than 0.2dB two-way insertion loss.Fig. 4.T est car equipped with imaging radar: (a) front-end, (b) base sys-tem, (c) operation and visualisation display.The base system is rack-mounted together with its AC 230V power supply in the trunk of the estate car (see figure 4b). An additional component placed there is a second PC provided for the intended implementation of safety or comfort applications. In the current status of the set-up it serves for synchro-nised video documentation and is connected to the radar control PC via Ethernet LAN.For GUI operation of the system and the on-line radar image visualisation a dis-play is attached at the dashboard (figure 4c). Note the junction on the left hand side recognisable in the instantaneous radar image.3.3Data ProcessingThe imaging radar data processing is performed in the following subsequent stages: radar data pre-processing, composition of radar images, image pre-pro-cessing, and conditioning for visualisation. Most of the pre-processing is per-formed in the DSP card, primarily computation of the Doppler FFT s for each resolution cell and maximum search in the Doppler frequency spectra. The resulting range profiles of reflectivity and associated Doppler values have to 105be assembled into the actual 2D radar images. As radar acquisition is not syn-chronised with the antenna pointing direction, this is done based on the encoder values and interpolating onto a fix azimuth grid. The antenna scan speed is controlled in a feed-back loop including the complete processing chain, so that the azimuth increment between subsequent range profile meas-urements is exactly the 3dB beam width (Nyquist condition). With the cur-rently used antenna this results in 16 azimuth directions per scan. Range is typically sampled from 5m to 150m at 1m resolution, resulting in raw radar images of 16·145 pixels. Range dependent amplitude correction is performed by R p with an exponent p~1 as a good compromise between point target detectability and noise limitation at larger ranges.Some image pre-processing is performed in order to reduce artefacts caused by system deficiencies or physical effects. Cross-coupling in the transceiver or antenna leads to near range echoes at zero Doppler. They are blanked by a kind of adaptive MTI filter. Because of the relatively low side-lobe suppression of the antenna cross-range blooming of strongly reflecting objects occurs. It is reduced by appropriate lowering the level of those pixels having the same range and Doppler as this object. Another physical effect occurring in the pres-ence of strong reflections is double bounce resulting in false echoes at twice range and twice Doppler in the images. They can be eliminated by pixel-wise checking for this condition.In order to achieve a proper mapping of intensity values into indices suited for an image colour coding, low and high level clipping has to be performed on the logarithmic values. A heuristically optimised choice is: low level clipping at 10dB above noise floor (this is the above specified SNR) and establishing a dynamic head room of 20dB. The noise floor can be computed directly from the measured data by averaging the intensity of target-free resolution cells,which allows a brightness control of the radar images independent of any sys-tem parameters.For visualisation conditioning 2D interpolation of the radar data has to be per-formed, which favourably is done directly in the desired co-ordinate system,either Cartesian (PPI plot) or vanishing point projection with direct compara-bility to optical vision. Due to the moderate FOV , trigonometric approximations can be applied in the transform formulas, which minimise the computational effort. Final step is combining intensity and Doppler matrices into a single one for pseudo-colour coding of a specific colour-map.All of the described data processing could be implemented on the base-system PC controller without significant reduction of real-time capability. With the above mentioned radar and imaging parameters an update rate of 3Hz results.Safety 106By reduced range and Doppler processing settings it can be increased to 10Hz. In addition to visualisation the acquired data can be recorded either in MA T-LAB binary file or TIF image format for off-line processing. For future on-line data evaluation in the application host the image data can be transferred via the LAN interface.3.4Imaging PerformanceThe sensitivity of the mobile instrumentation radar could be verified as pre-dicted in the system design. Hidden vehicles proved to be detectable in all rel-evant traffic situations. Roadsides can typically be recognised up to a range of 70m, provided they consist of grass or gravel. Road curvature prediction based on real clothoid parameter modelling and tracking in consecutive images will work clearly farther. In many cases the prediction is eased by the presence of structures parallel to the road (trees, shrubs, fences, guard rails, poles, walls, slopes, etc.).Radar echoes from the underbodies reliably appear in two-dimensional repre-sentation with correct dimensions and alignment in the radar images and encourage the development of corresponding classification algorithms for traf-fic scene interpretation.Spurious objects are to be found regularly in the case of guard rails, walls, metallic fences, or kerbstones parallel to the road. Due to detour propagation vehicles appear virtually mirrored on the other side of these reflecting areas. The forward reflectivity even of low kerbstones is very high, explicable by their dihedral appearance. But here an exploitable effect becomes evident: Although nearly no backscatter can be observed from kerbstones, occurrence of multipath reflections of preceding vehicles allows localising the roadside in the middle between direct and virtual image. This expands the capability of roadside recognition.4ApplicationsIn the previous sections some novel applications for an automotive high reso-lution radar with imaging capabilities have already been addressed. Currently it is presumed that the following functionalities can be achieved or at least supported by such an environmental sensor:Improvement of ACC function (higher speed, wider range, country road use).Obstacle warning (including stationary objects - for example rear end of traffic jam).Emergency breaking.Collision avoidance.Stop-and-go traffic support.Detection of pedestrians.Identification of parking space.Curve warning.Visibility enhancement.Some of these are not stand-alone applications, but have to be seen in combi-nation with others. Parking space identification would be an interesting enhancement for guided or automatic parking systems, which currently are under development. The sensing capability of high resolution radar has been investigated by measurements in according situations and is illustrated in fig-ure 5. A free parking space can be identified clearly earlier than by visual inspection and a rough size determination is possible (the free space in the analysed scene was 5m long).With respect to safety applications pedestrian detection also can't be an autonomous feature, as the spatial resolution of the imaging radar won't allow classification of persons. But localisation of potentially relevant objects would be a very important input for sensor fusion approaches. Radar can identify regions of interest (ROIs), in which detailed analysis based on video image pro-cessing , e. g., is performed [8]. This provides also the information redundan-cy, which is required in safety systems, as radar and video sensing is largely complementary.A specific contribution of radar can be the detection of pedestrians hidden by vehicles, for example at a bus stop. Here again the wave duct effect between road surface and vehicle underbody becomes beneficial. This could help to recognise situations of persons abruptly entering the roadway (playing chil-dren) at an early stage. Radar measurements have been performed indicating that persons can be detected reliably in front of a vehicle, provided the spac-ing is wider than the range resolution (1m in the current system realisation). Figure 6 shows an example with a person in front of a minivan.An interesting application based solely on radar information could be a kind of "curve assistant", which warns the driver in the danger of overshooting a curve. Exploiting the capability of continuous roadside detection even in the absence of any border structures, the road course and its curvature can bedetermined and related to the actual speed, which is directly available from the Doppler data. Figure 7 gives an impression of the roadside detection per-formance in the situation of a narrow country road. Maximum acquisition range has been 100m. In this example a vanishing point projection has been applied to the radar image.Fig. 5.Capability of free parking space identification (radar image in PPI representation).Fig. 6.Detection of a pedestrian hidden by a parked vehicle (radar image in PPI representation).Fig. 7.Roadside detection capability (radar image in perspective repre-sentation).5Conclusion and OutlookAutomotive radar is expected to be a key technology improving driving safety in future, especially due to its inherent advantages (weather independence, direct acquisition of range and velocity). In this contribution the potential of radar sensors with high resolution in azimuth and range has been pointed out. They deliver images with high information content and considerably smaller amount of data in comparison to video images. A prototype of an automotive instrumentation radar has been realised, which allows on-line acquisition and real-time visualisation of radar images with an update rate of up to 10Hz. It could be shown that by moderate increasing of resolution, angular coverage, and sensitivity with respect to existing automotive radar sensors a new quali-ty of environmental sensing can be established. It enables a fundamentally new approach of radar data interpretation: image processing based scenario analysis instead of point target tracking. This opens up new perspectives of comfort and safety features in future automobiles. The practical implementa-tion of a prototypic mobile imaging radar proves technical feasibility at system design parameters, which are not contradicting to commercialisation aspects like complexity, size, and cost.Future activities will be hardware- and software-related as well. Mass produc-tion realisation aspects of the front-end (antenna and millimetre-wave elec-tronics) have to be clarified. Autonomous implementation of the above men-tioned comfort or safety features requires the development of radar image pro-cessing algorithms (based on the adaptation of established methods like edgedetection, segmentation, clustering, tracking, object classification) and scene interpretation according to the particular application. An important aspect will also be fusion of radar and vision data, for which an optimised concept has to be worked out.References[1]J. Wenger, R. Schneider, M. Stotz, B. Danner, W. Lauer, R. Nieuwenhuizen, R.Adomat: Forward Looking Radar Activities at DaimlerChrysler; Workshop on Automotive Millimetre-Wave Radar Systems (WS 3), EuMC 2000, Paris, France, Oct. 3, 2000, pp. I,1-I,8.[2]R. Schneider, G. Wanielik, J. Wenger: Millimeterwave imaging of traffic scenarios;Intelligent Vehicles ‘96, T okyo, Japan, Sept. 18-20, 1996, pp. 327-332.[3]R. Schneider, J. Wenger, G. Wanielik, H. Neef: Millimeter-wave images of trafficscenes and their automatic interpretation; Conf. Proc. Microwaves and RF, London, UK, Sept. 30 - Oct. 2, 1997, pp. 239-244.[4]R. Schneider, J. Wenger: System Aspects for Future Automotiv…e Radar; Proc. ofthe IEEE MTT-S Microwave Symposium, 1999, pp. 293-296.[5]R. Schneider, D. Didascalou, W. Wiesbeck: Impact of road surfaces on millimeterwave propagation; IEEE T rans. Veh. T ech. Vol. 49, No.4, July 2000, pp. 1314-1320.[6]K. Solbach, I. Wolff: Dielectric Image Line Groove Antennas for Millimeter Waves,Part II: Experimental Verification; IEEE T rans. AP, vol. AP-33, No. 7, July 1985, pp.697-706.[7]V. Manasson, L. Sadovnik, R. Mino: MMW Scanning Antenna; IEEE AES SystemsMagazine, October 1996, pp. 29-33.[8] B. Heisele, N. Neef, W. Ritter, R. Schneider, G. Wanielik: Object Detection in T rafficScenes by a Colour Video and Radar Data Fusion Approach; First Australian Data Fusion Symposium ADF-96, Adelaide, Australia, November 1996, pp. 48-52.Robert Schneider, Josef WengerDaimlerChrysler AGResearch & Technology, REM/CRWilhelm-Runge-Str. 1189081 UlmGermanyrobert.r.schneider@Keywords:automotive radar, environmental sensing, driver assistance, autonomous cruise control, obstacle warning, collision avoidance.。