Ripple研究

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动态水面和波纹动画的研究(IJITCS-V2-N1-3)

I.J. Information Technology and Computer Science, 2010, 1, 18-24Published Online November 2010 in MECS (/)Research on Dynamic Water Surface and RippleAnimationYufen. FengDepartment of Mathematics and Information Science, Tangshan Normal University, Tangshan, ChinaEmail: fengyufen_ts@Haiyan. FanDepartment of Mathematics and Information Science, Tangshan Normal University, Tangshan, ChinaEmail: fhy_sea@Abstract—Dynamic simulation of waters is a significant research subject, but the research and simulation of the water drops generating ripples is relatively less. The research on the ripples motion is great significance due to the indispensability of it in the special environments. In our research, we study the method of adding dynamic water ripple effects in 2D image on Web page, 3D animation and virtual reality. By the means of shape simulation, we add animation effects for the web page through creating cells of table combined with transparent special effect files of Flash. we achieve the good reality ripple effect by using simple dynamics and kinematic principle to create models in the 3D animation. By using the combination of 3dMax and Realflow software, we achieve more realistic simulation of the effect of dripping ripple. In the virtual reality system, the appropriate algorithm is applied in program to simulate ripples correctly. These methods are applied to different environments and the results are realistic.Index Terms—dynamic water surface, ripple animation , flash in web, 3d animation, virtual realityI.I NTRODUCTIONDynamic water simulation is a very significant issue, it is a hot spot of research for the surface reflection, refraction and surface wave effects of the dynamic simulation .With 3D games and the popularity and in-depth of virtual reality applications, most of the games and virtual reality software is often the help of dripping ripple effects to enhance the game's friendliness and realism. Achieve dripping ripple simulation, the principle of particle system principle, the principle of light refraction and reflection wave propagation and attenuation characteristics are calculated, and as much as possible to achieve rapid and real display effect. How to simulate the natural phenomenon such as rain, snow, smog and flame is always difficult and important for computer graphics and virtual reality .The dynamic simulation of water surface is a research subject that it has great theory value as well as practical significance. The research of the reflection and refraction of waves has become a hot topic for researchers all over the world[1-5]. The research on the ripples motion is of great significance due to the indispensability of it in the special environments. On the calm and tranquil surface, the ripples will appear unless external objects perturb the water. If the perturbance stops, the surface will became calm again after some time. The wave moving of 2D wave equation is in concert with the phenomena, the literature references put forward a simulation method of ripples on small water surface which creates surface modeling by using the method of Johanson ’s projection grid, solving equation by the programmable GPU technology and simulating ripples perfectly by an appropriate algorithm[6-7]. The literature reference simulates the raindrops by solving 2D shallow water equation which describes flow phenomenon through SPH method, using the distortion form of Mon-aghan artificial viscosity according to the concrete model[8]. In the paper the drip ripple effects produced based on GPU ,Xia Yan used three optimization methods ,they are some approximation methods , simulating 3D effects by 2D bump texture and writing shader programs, he produced the described methods of ripple effects [9].In this paper we research on the method of adding dynamic ripples in 2D image on web page, 3D animation and virtual reality system. The simple dynamics and kinematic principles are applied in the 3D animation to simulate the ripples reality. In the 2D image on the web page and the virtual reality system we just used shape simulation effects but not complex physical models for the ripples effects. These methods are simple and practical, the effect is very vivid and realistic. These can be used for a variety of scenarios need to ripples or waves, such as rain water, pond or lake with fountains, etc.II.RESEARCH OF RIPPLE EFFECTS IN2DENVIRONMENTA. Flash animated raindrop ripplesIn some wonderful films we often see the effects of the slightest rain which giving a warm and romantic feeling. When a piece of stone is thrown into the pond, water surface ripples are spreading around, the ripples in a circular form will get bigger and bigger and fade away slowly, the water will restore calm soon. According to this natural phenomenon, we simulate raindrops the ripple effects falling from the air into the river with flash software.Figure 1. raindrop and ripple.First we produced the formation of ripple effects of rain falling on the ground . Create a new movie clip symbol which is named ripple, open the editing area of the movie clip symbol, use the ellipse tool to draw a water cycle of circle round and fill gradient. Add some codes of action scripting language for the water cycle. The codes are as follows:// Effect Codes , 1 is the static wave ，2 is fluctuation code = 1;n_a = 45; // amplitude factor v_a = n_a;n_a_n = 8; // static volatile factorn_a_random = 100; // fluctuation amplitude factor scale = 20; // scaling factor n_scale = 10;v_scale = n_scale;n_alpha = 1; //alpha facto v_alpha = n_alpha; mc._visible = 0;i_max_random = 0; // the maximum number of factors water cyclei_max = random(i_max_random)+10; i = 0;time_max_random = 20; // copy the interval factor time = 0;time_max = 8;time_sin = 0; // still time factor volatility mc.duplicateMovieClip("mc"+i, i);// create a new attribute s, the volatility factor this["staut"+i] = new Object(); this["staut"+i].s = 0; i++;onEnterFrame = function () {time_sin++; if (time_sin>360){ time_sin = 0; } // hydrosphere copy the codes if (i<i_max) {time++; if (time>=time_max) { time = 0;mc.duplicateMovieClip("mc"+i, i); this["mc"+i]._xscale = this["mc"+i]._yscale=scale; this["staut"+i] = new Object(); this["staut"+i].s = random(180);this["staut"+i].a = random(n_a_random)+n_a_random; if (code == 1) {this["mc"+i]._y= Math.sin(Math.abs(time_sin/n_a_n))*n_a*2; }i++; }} // Hydrosphere zoom codes for (j=0; j<=i_max; j++) {this["mc"+j]._xscale= this["mc"+j]._yscale += v_scale;this["mc"+j]._alpha -= v_alpha; if (code == 2) { // the codes of fluctuations this["mc"+j]._y=v_a*Math.sin(this["staut"+j].s++)*this["staut"+j].a/this["mc"+j]._yscale;} // Initializationif (this["mc"+j]._alpha<0) { if (code == 1) {this["mc"+j]._y=Math.sin(Math.abs(time_sin/n_a_n))*n_a*2; }this["mc"+j]._alpha = 100;this["mc"+j]._xscale = this["mc"+j]._yscale=scale; this["mc"+j].swapDepths(i++); } } }; stop();Second we created a movie clip symbol showing the raindrops dripping from above to the water surface and disappeared into the water ,and named the movie clip of the name as raindrop, the symbol of ripple and the symbol of raindrop were merged together to create a movie clip symbol named drop ripple. Finally, in the main scene ,create a instance named raindrop1, and add the following actions scripting languages ： // define and initialize variables n = Number(n)+1;// Set of random coordinates of the object raindrop1 setProperty("raindrop1", _x, -30+Math.random()*550); setProperty("raindrop1", _y, -35+Math.random()*26); //continue to reproduce the object raindrop1 duplicateMovieClip("raindrop1", "", n); Add action in frame 2: gotoAndPlay(1);Fig . 1 shows the number of raindrops falling into the water produce ripples and ripples overlap .B. ADDING RIPPLES IN IMAGE ON WEB PAGEIn the web page, some photos and rendering pictures are used frequently to make beautiful picturesque scenes that the green glass looks like a carpet, the bouquets of flowers are a mass of blossom, the lake and the hills add radiance and beauty to each other, the mountains are clear against the sky and the waters is very bright. In most cases, the water is flat. If there are some ripples andwaves on the water surface, it can make the whole web page full of variety and lifelikeness .When we process the picture, a method which can combine the effective ripple file of Flash with the picture is adopted to achieve the good reality ripple effect. First distribute the resource files of Flash, convert .fla format file to .swf format file. Then create a table in the web page, take the .swf format file as background of the table, the table size can be adjusted by the picture size, create cells in the table, insert the ripple special files in the appropriate cell, set the background color of the ripple animation to be transparent. The animation file can be used in the whole table, we can insert several ripple files in a table, too. Fig. 1 is ripple animation effect in Flash file; Fig. 2(a) is a photo with two fountains.Here are some resource codes after inserting Flash file in the cell on web page.<td><script type="text/javascript">AC_FL_RunContent( 'codebase','http://download.macr /pub/shockwave/cabs/flash/swflash.cab#versi on=6,0,29,0','width','200','height','120','align','absbottom',' src','image/lyxg','quality','high','pluginspage','http://www. /go/getflashplayer','movie','image/lyxg' );//end AC code</script><noscript><object classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" codebase="/pub/shockw ave/cabs/flash/swflash.cab#version=6,0,29,0"width="200" height="120" align="absbottom"><param name="movie" value="image/lyxg.swf" /><param name="quality" value="high" /><embed src="image/lyxg.swf"width="200" height="120"align="absbottom"quality="high"pluginspage=/go/getflashpla yer type="application/x-shockwave-flash"</embed></object></noscript></td>The ripple effects animation file is called lyxg.swf, the file is in the image directory of the website. We use the transparent ripple effects animation file by inserting the sentence ‘‘wmode ’,’transparent’ ’before the sentence ‘'movie',' image/lyxg'’. The codes after the modification are as follows.AC_FL_RunContent( 'codebase','http://download.macr /pub/shockwave/cabs/flash/swflash.cab#versi on=6,0,29,0','width','200','height','120','align','absbottom',' src','image/lyxg','quality','high','pluginspage','http://www. /go/getflashplayer', 'wmode','transparent', 'movie','image/lyxg' );//end AC codeFig.2 (b) is a picture added the dynamic ripples which will increase vigor for the web page.III. THE KEY TECHNIQUES OF DEVELOPMENT OFRIPPLES IN3D ANIMATIONThe realistic water effect is a bit complicated in 3D animation. In a large water surface such as sea ,ocean , lake or broad river in the scene, the DreamScape of 3D Max landscape plug-in can be used and can generate the reality effect including the dynamic phenomenon such as foam and wavy etc. And the rendering speed is faster. When some objects drop to water surface, if you want to show the collision between the objects and the water, the reactor dynamic system in 3D Max can be used . To show rain or fountain effect we can use the super spray particle that the direction of injection is down under the action of gravity space warps and add some motion blur. If you want to show the details, the fluid dynamics simulation software RealFlow can be used. It can accomplish the projects which include the objects arousing waves, fluctuating with water, splashing, generating some ripples after the particles falling into the water, and producing wake by the rapid movement objects, spray and waves. It is used to simulate the sailing ships usually. The paper studies the general ripples, we can show the effect directly by the material, modifying the reflection and refraction coefficient, adding noise bump map to response the slight wave on surface, binding water into ripple space warp and modifying the correlative parameters in order to generate ripples animation effects[10-11].A. Relative modelThe surface is the plane divided into many small segments. There are more detailed segments; there is more realistic ripple effect. However, there are more surfaces, the rendering is slower. Therefore, we should consider the actual situation roundly to determine a reasonable value of segments. We Create a ripple space warp for generating ripples, the parameters of wavelength,(a) Photo of lakeFigure 2. (b) Adding ripples animationamplitude, phase, and display should be modified according to the specific scene. Droplet model can be considered from two cases. First if the sense of reality is emphasized, the method which make a simple sphere bound to a FFD space warp can be used to simulate water droplets precisely by modifying the control point. Second, if the droplets model is too complex, it can affect the speed of animation rendering in the droplets too many cases, so we can use the multi-faceted sphere to simplify the droplet model, the noise space wrap can be added to the sphere ,then we change the shape by modifying the ratio , intensity and phase parameters to avoid the same shape of sphere in a large number of water droplets .B. Lighting and MaterialsWater is a transparent liquid basically, but water color of the rivers and lakes is affected by many factors, such as the intensity and color of external light, the depth of the water and the impurities of the water. All of the external factors affected the effect of the reflection andrefraction of the water directly. And the reflection and refraction of the water is the key to describe the real surface. In the 3D software, we can set the surface material to adjust the reflection channel to add the falloff image, set the glossiness, set the subdivs, set the refractivity, and set the fog color to adjust the color of the water to change the parameters such as the fog multiplier. So lighting and material setting are the key factors to the realistic dripping and ripple animation, VRay is a small plug-in launched by the famous 3D max plug-in provider Chaos group, but it is a extremely powerful rendering plug-in. VRay lighting type is very rich, it provides the sun lighting, the sky lighting and VRay lighting, the user can use the standard lighting and photometric lighting in 3D Max, too. In the indirect lighting, you can set the parameters such as global optical caustics, global Light color, Quasi-Monte Carlo Global Light and light rebound etc to control scene lighting effects. VRay renderer provides a special VRayMtl material. Using the material in the scene can get a more accurate physical lighting, a faster rendering speed, a more convenient parameter adjustment of reflection and refraction. The different textures can be applied to control the reflection and refraction, adding the bump map and displacement map. In our research, the water material type is VRayMlt , this material should be reflective, the diffuse parameter controls the reflection effect of material, the Degree of the reflection controlled by the color of diffuse, the white color means the strongest reflection, the black means no reflection ,so we need to give the ideal reflection to watersurface. The refract parameter controls the refraction effect of material, that is the transparency of the water, as with the refraction white means that the water is completely transparent, black means the opaque. Usually we set the refract color of the pool water material as white, revise the refractive index to 1.333, add noise in the bump map to show the microwave of surface effect ， adjust the value of the right size and bump, add the falloff in the diffuse map to show the color change in the near and far surface. In addition, we can adjust the fog color to change the water color.C. Animation implementWe can create large droplets by super spray in particle system; the particle type is solid geometry. Selecting the droplets as picked objects in the instance of the parameter in the dialog box, modify the axis offset and plane offset in the particle distribution dialog box, adjust the value of particles number and particle generation time and particle velocity and particle size in the particle generation dialog box . To enable the droplets landing, create a gravity space wrap in the position nearest the ground. The droplet model is bound to gravity space wrap, modify the intensity of gravity, the droplets are ejected to the surface and drip to water at a ideal speed. When the droplets are dripping onto the water, the ripple will be generated on the surface. The effect need to bind the surface models to distort the ripple space wrap, press the auto key button again in key frame which the water droplet is dripping. Then find the frame in which the ripple disappear, modify the value of the phase, so over and over again, until satisfied. Finally render output, and generate animation file.Fig. 5 is a picture in the animation file, we can see the drippings and the water ripples on the surface clearly.Figure 3. Water surface and droplet modelFigure 4. Setting the water material parametersD. RealWave in RealFlow and simulation of rippleRealFlow is a very good simulation of fluid computing software, RealWave dedicated to simulation of surface waves, such as sea water after an object thrown into ripples, driving the boat in the water (including waves and the spray of particles thrown water and drag generated tail). The project completed include: the object falling into the water after the waves stirred up and up and down with the water, but also generate splash; particles float to the surface of the ripples on the water fall; in the fast moving objects on the surface of the water generated wake, spray and waves, commonly used in the simulation of vessels; performance of dynamic, natural fluctuations in the water, such as lakes, ponds, oceans, waves splashing the shore can also produce water spray effects.In Realflow software we add a Realwave entity to the scene to simulate water. By adjusting the parameters of scale and polygon size of the surface water to determine the precise extent of the model. Rain drops can be simulated by creating a simple sphere, the dynamics property of the sphere is set to rigid body, the daemon of gravity is added in the scene ,so the rain drops will fall in the water under the action of gravity. In order to create some small sprays when when the raindrops are thrown into the water, we need to add Rw_splash particle emitter in the scene. The raindrop spheres are specified for the objects of the Rw_splash , so that water droplets will splash when they are falling to the water surface. the size and number of spray can be determined by adjusting the parameters of Rw_splash. To make ripples on the water better, you can add control points on the real wave, set the control point parameters, such as frequency, amplitude, begin time, cycles and wave speeds etc. After regulation in the simulation ,the particles or the grid objects are exported to other mainstream 3D software from RealFlow software for lighting and rendering.Fig. 6 is the simulation results in Realflow,Fig.7 is the rendering after export.IV. RESEARCH OF RIPPLES ANIMATION INVIRTUAL REALITY SYSTEM Virtual reality technology is a human-computer interacting technology which can simulate the human behaviors such as the visual, auditory, tactile and motor etc. Immersion, interaction and imagination are the main features of it. The ripple effects simulated in is off-line and non-real-time. In the first two application environments, virtual reality environment is different, it emphasizes the interactive and real-time. When a person goes into the virtual system, it seems that he involves in real environment. If there is a fountain in the lake, the user should be able to control the switch of the fountain. To experience some special effects in the virtual environment, users may add rain, snow and other natural phenomena to change the weather. In the paper we studied the effects of droplets and ripples in virtual reality system based on Virtools.A. Implement of water surface,droplets and rippleWe can simulate the surface and generate more accurate reflections and refractions through adjusting light intensity and colorimchy by lighting and perturbing 2D texture mapping with normal mapping. A shader program in Virtools had been written and applied in virtual reality project. In the actual operation the effect is real and the rendering speed had greatly increased. Droplets generation is achieved by particle systems. According to the different condition of the launching Virtools provide us with nine particle system. In the paper we use a plane particle system to get the drippings in the natural environment by adjusting the particle rotation angle ,the particle velocity, the particle life cycle,the particle emission, and the particle size parameters.Figure 5.Droplets and ripples effects in animationFigure 6. Modeling in RealflowFigure 7. Rendering after exportThe basic shapes of ripples are simulated by mapping the transparent texture material to 3D entities, when the droplet is falling, we will test whether it has a collision with the surface. If the collision happens, we will obtain the coordinate of the collision point. At this point we create a 3d entity with texture of ripple and assign the initial value of the entity size and the transparency of the material. Then we amplify the entity by a certain coefficient. At the same time, reduce the opacity of the material, when the ripple entity amplifies to a certain extent, the transparent coefficient will reduce to zero, the ripple disappears and the water becomes calm again. Finally, the ripple entity is deleted from the scene. This simulation method is not only simple, but also it is not high demand on the system resources. The animation effect is very realistic. Fig. 8 is the algorithm flowchart of ripple implementation procedure.B ．shader shader in virtoolsWith the GPU computing capabilities and the development of high-level shading languages, the vertex shader, pixel shader, the normal vector calculation and the dynamic fluctuations in the water, reflection and refraction of the operation can be completed by GPU. Virtools is a rich interaction module of real-time 3D virtual scene editing software. It can produce many 3D products with different uses[12]. Virtools support senior rendering language of DirectX9 fully. Virtools develops a shader reference, all kinds of usages and the value of the state parameters can be seen[13]. Writing programs foreach shader is that some parameters are filled in, theseparameters can be filled in material properties page and can be filled by BB( Building Block). A shader program can contain one or more techniques, but there is only one technique applying to render materials. Each technique may contain one or more passes, each pass execute sequentially according to their order defined. Each vertex and each pixel is executed in every pass in order to complete different purpose of render[14].It is mysterious for us that one can obtain the intuitive visual feedback of code by shader programming at once. You can also realize a tree sway with real-time dynamic swaying effect of a leaf on the lake by shader programming. But it needs to consider the necessity using shader in order to utilize the computer system resources rationally.C. effect of implementThe algorithm has implemented by writing a program in the Virtools. Virtools is a real-time editing software with many rich interaction modules for 3D virtual reality, real 3D virtual reality editing. It can produce many 3D products with different uses, such as the Internet or computer games, multimedia, architectural designs, interactive television, education and training, simulation and product display [15-16]. In the paper, we increase the size of ripples intentionally to see the ripple effects clearly. When the viewpoint is close, we can reduce the physical size of the ripples. If the droplets generate intensively, the ripples will interfere with each other, so we only observed the emergence and disappearance of two ripples in the experiment, the effect is true and the speed is faster in running.V. CONCLUSION In the paper we use the method which can combine the effective ripple file in Flash with the table cell in webpage. It is simple and general and can add animationFigure 8. The algorithm flowchart of implementationFigure9. The shader editor interface in virtoolsFigure 10. The effects of ripples in virtual reality sceneeffects for web page quickly and flexibly. In 3D animation environment, we create models by using simple dynamics and kinematic principle, using VRay lighting and VrayMtl. Water droplets model is generated by a particle system. The water surface is a plane with many small segments, it is bound a ripple space wrap, we adjust phase and wavelength of ripple on different key frame. In virtual reality system, we show the reflection and refraction of water by writing shader program, apply the shape simulation method to realize the effect. The method is simple and the effect is true. But its weakness is that the ripples size should not be too big and the number of water droplets should not be too much. These measures could offer a reference for the users who want to realize ripple animation in different environments.R EFERENCES[1]Zhao Ping ,Chen Dingfang,Jiang yun. “The application ofshader in the development of visual scence based on Cg”,Journual of Hubei University of Technology,Jun. 2007,Vol.22,No. 3, ,pp.65-67(In Chinese).[2]Cheng Yongxin,”The research and implementation of thelarge water surface realtime render and scene management” In 3D Engine,Master Dissertation,Universityof Electronic Science and Technology of China,2009.4 (InChinese)[3]Tan Xiaohui,Wan Wanggen,Yu xiaoqing,Cui Bin , “Realtime simulation of large scale water surface based on GPU” in Computer Simulation., May. 2009, Vol. 26,No. 9pp.211–214(In Chinese).[4]Wang Daochen,Wan Wanggen,Tang Jingzhou,ChenHuajie.”Real-time rendering alogrithm for water surfacebased on GPU” in Computer Engneering,Oct.2008, Vol.34,No. 20, pp.233–237(In Chinese).[5]Zhang Long,Zhang Yubo,Chen Wei,He Jian “Real-timesimulation of dynamic wetland scence” in Journal of Computer-Aided Design&Computer Graphics, Aug. 2008,Vol. 20,No. 8,pp. 1007–1010 (In Chinese).[6]Cheng Tiantian,”Research on dynamic water scenemodeling method for Tai Lake water area.”, Master Dissertation ,Suzhou University,2008.4(in Chinese)[7]Lu Weiliang,Cheng Tiantian,”The simulation method ofripple on small waters”in Computer Engineering and Applications, Apr.2010,Vol. 46,No.19,pp.193-195,199(InChinese).[8]Li Yumei,Wang Jiwen, “Simulation of ripples based onsmoothed particle hydrodymatics method” in ComputerTechnology and Development,May 2010,Vol. 20,No.5,pp.56-58,62(In Chinese) [9]Xia Yan, “Dripping ripple effects production based onGPU” in Computer Application, May 2007,pp.62-64[10]Han Liang,Wang Wenyong,.”The rain simulation of virtualreality Scene based on particle system” in The Proceedingsof the 14th National I Image & Graphics AcademicConference,2008 (In Chinese)[11]Chen Qianhua,Deng Jiansong,Chen Falai. “Simulation ofripples” in Journal of Computer ReSearch &Develoption.May 2001,Vol.38,No.5,pp.524-528(In Chinese).[12]Frank D.Luna Introduction to 3D Game Programming withDirectX 9.0 ,Copyright 2003 by Wordware Publishing.[13] Fu Zhiyong ,Gao Ming, Three Dimensional Game Designby Virtools Dev 4.0,Beijing:Tsinghua UniversityPress,(2008).[14]Wang Dandong,Xu Yingxin etc.in: Treasury of Knowledgeof Designer on 3D Game,edited by Ceap Electronic &Audiovisual Press（2009）[15]Fu Zhiyong ,Gao Ming, Three Dimensional Game Designby Virtools Dev 4.0,Beijing:Tsinghua UniversityPress,Oct.2008(In Chinese).[16]Wang Dandong,Xu Yingxin,Xu Lin.Treasury ofKnowledge of Designer on 3D Game,Ceap Electronic &Audiovisual Press,May 2009(In Chinese).Yufen. Feng was born in Yutian County, Tangshan city, Hebei province in Mar. 28th, 1970. IShe graduated from Lanzhou University and majored in Computer Science and received a B.S Science degree in 1992. She received a M.S degree from University of Science & Technology Beijing in 2010.She worked at Tangshan Architecture Planning and Design Institute between 1992 and 2005. Now she is working as a teacher in Department of Mathematics and Information Science Tangshan Normal University,Tangshan, China. She has published some papers which include: “Design and Realizationof Roaming system of a Virtual Community Based on Virtools”in Computer Simulation, “Research of Building Virtual Scence Based on Geometry and Image” in Computer ProgrammingSkills & Maintenance etc. She is interested in graphics and image processing, she has been engaged in the direction of Virtual Reality.Haiyan. Fan was born in Laoting County, Tangshan city, Hebei province in June 20th, 1974. She received the EconomicsB.A. degree in 2000 from Shandong Institute of Business and Technology which is in Yantai city, Shandong Province, China.She is working as a teacher in Department of Mathematicsand Information Science Tangshan Normal University, Tangshan, China。

电源分配网络的直流压降分析与研究

电源分配网络的直流压降分析与研究作者：张晓雄来源：《电子技术与软件工程》2016年第18期摘要随着半导体技术的不断发展和PCB布线密度的增加，电源分配网络（PDN）的直流压降问题在设计过程中需要得到足够的重视。

针对造成直流压降问题的主要因素，在理论分析的基础上对电源分配网络的原理设计和PCB设计提出建议，减小直流压降对电源完整性的影响。

【关键词】电源分配网络直流压降电源完整性1 引言当前的系统设计中，器件的核心供电电压持续减小，电压容差也越来越小，工作电流和PCB布线密度则越来越大，导致直流问题日益突出。

如果在设计中不考虑直流问题，很可能因为直流压降导致噪声容限下降，造成系统工作不稳定，甚至无法正常工作。

过大的电流密度还可能引起局部温度持续升高甚至造成PCB的损坏。

因此，在产品设计过程中，针对核心关键电源分配网络进行直流压降控制，降低直流压降的影响是保证电源完整性的首要任务。

2 直流压降与电源完整性2.1 电源分配网络电源分配网络，包含从稳压模块（VRM）到芯片的焊盘，再到裸芯片内分配本地电压和返回电流的片上金属层在内的所有互连。

电源分配网络是系统中最复杂的互连结构，网络中任何一个部分发生改变，都会对整个系统的性能造成影响，在设计过程中必须认真对待每一个细节。

电源网络的直流通路可简化为图1所示电路。

V为等效的理想电源，Rvrm为VRM的直流输出阻抗；Rpcb为PCB上的电源地平面、过孔、互连等的直流阻抗；Rsink为负载芯片内的封装、键合线等的直流电阻；Isink为负载芯片的工作电流。

其中Rpcb是设计中对直流压降影响最大的部分。

2.2 直流压降对噪声容限的影响在进行电源完整性分析的过程中，通常都会使用目标阻抗的方法进行分析与优化，目标阻抗的计算公式为：其中Vdd表示供电电压，Itransient表示瞬变电流，ripple%表示允许的纹波（电源噪声）。

在芯片的数据手册中查到的电压波动允许范围包含了电源噪声和直流压降两个部分的影响，因此在计算目标阻抗时，ripple%的取值需要减去直流压降所占的比例。

PRP基因在睾丸中的表达及其生物学功能初步研究的开题报告

PRP基因在睾丸中的表达及其生物学功能初步研究
的开题报告
研究背景和意义：
PRP基因（Proline-Rich Protein）属于一类具有高丰度、丰富的脯氨酸序列的基因，其在生物体中广泛分布，包括哺乳动物、鸟类、爬行动物等种类中都有表达。

PRP基因的主要功能是参与细胞凋亡、胶原纤维的合成以及组织修复等生物学过程，目前研究还发现其在生殖系统发育和成熟中也具有重要作用。

在睾丸中，PRP基因的表达模式和功能尚未被完全阐明，因此本研究将从睾丸中的PRP基因表达入手，初步探究其生物学功能。

研究内容及方法：
本研究将通过PCR扩增和Western Blot检测等方法，检测睾丸中PRP基因的表达情况，并对PRP基因进行亚细胞定位扫描。

同时，将采用荧光原位杂交技术（FISH），对PRP基因在睾丸中的表达位置进行初步定位。

最后，将利用RNAi技术对PRP基因进行干扰，观察PRP基因的敲除对睾丸生物学功能的影响。

研究意义：
PRP基因作为一类重要的细胞因子，其在生物学过程中具有多种作用。

本研究选取睾丸作为研究对象，旨在初步探究PRP基因在生殖系统中的表达和生物学功能，为深入了解PRP基因的作用机制提供一定的参考依据，并为新型生殖调控策略的开发提供理论依据。

电源滤波电容大小的计算方法

电源滤波电容大小的计算方法(总2页)--本页仅作为文档封面，使用时请直接删除即可----内页可以根据需求调整合适字体及大小--问题: 请问电源的滤波电容的通常是一个大的并联一个小的，两个相差100倍，但是那个大的电容有的用10u，有的用47u，还有的用，这是怎么回事，应该怎么选择啊大的是电解电容，滤波用的，选择的话，我感觉是看输入的电压质量的，如果本身纹波很大，或者对纹波要求很严格，那就用大的电容。

小一些的是去耦电容，我感觉和滤波差不多意思，就是防止电压波动的。

容值要小一些，高频时候作用大。

电源滤波电容大小的计算方法电源滤波电容大小的计算方法(有人说:没有仔细看，但结论似乎不正确)C=Q/U----------Q=C*UI=dQ/dt---------I=d(C*U)/dt=C*dU/dtC=I*dt/dU从上式可以看出，滤波电容大小与电源输出电流和单位时间电容电压变化率有关系，且输出电流越大电容越大，单位时间电压变化越小电容越大我们可以假设，单位时间电容电压变化1v（dV＝1）（可能有人说变化也太大了吧，但想下我们一般做类似lm886的时候用的电压是30v左右，电压下降1v，电压变化率是％，我认为不算小了，那如果您非认为这个值小了，那你可以按照你所希望的值计算一下，或许你发现你所需要的代价是很大的），则上式变为C＝I*dt。

那么我们就可以按照一个最大的猝发大功率信号时所需要的电流和猝发时间来计算我们所需要的最小电容大小了，以lm3886为例，它的最大输出功率是125W，那么我么可以假设需要电源提供的最大功率是150W，则电源提供的最大电流是I＝150/(30+30)=(正负电源各），而大功率一般是低频信号，我们可以用100Hz信号代替，则dt＝1/100＝，带上上式后得到C＝×＝＝25000uF。

以上计算是按照功放的最大功率计算的，如果我们平时是用小音量听的话，电容不需要这么大的，我认为满足一定的纹波系数就可以了，4700u或许就已经够用了。

基于逆变器中直流母线电容的纹波电流的研究 pdf

基于逆变器中直流母线电容的纹波电流的研究 pdfIn recent years, the study of ripple current in the DC bus capacitor of inverters has gained significant attention in the field of power electronics. The DC bus capacitor plays a crucial role in filtering and supplying uninterrupted voltage to the load. However, due to the switching operation of semiconductors in the inverter, ripple currents are generated in the DC bus capacitor. Theseripple currents can have adverse effects on the overall system performance and reliability.在近年来的功率电子学领域中，研究逆变器中直流母线电容的纹波电流变得越来越受到重视。

直流母线电容在滤波和为负载提供稳定电压方面起着关键作用。

然而，在逆变器中半导体的开关操作过程中，会产生直流母线电容上的纹波电流。

这些纹波电流可能对整个系统性能和可靠性产生不利影响。

To understand and mitigate the effects of ripple current in the DC bus capacitor, researchers have conducted extensive studies. One common approach is to analyze the equivalentcircuit model of an inverter system with a DC bus capacitor. The equivalent circuit model allows researchers to simulate and analyze various operating conditions and parameters affecting the ripple current.为了理解和减轻直流母线电容中纹波电流的影响，研究人员进行了广泛的研究。

HOPE研究与雷米普利_防止心血管事件里程碑式的临床试验

HOPE研究与雷米普利_防止心血管事件里程碑式的临床试验突破心血管事件的黑匣子：HOPE研究与雷米普利心血管疾病作为当今社会的头号杀手，给人类健康带来了沉重的负担。

然而，在科学技术的不断发展下，人类对于这一领域的了解与干预手段也在逐渐向前推进。

作为一项划时代的临床试验，HOPE研究与雷米普利的结合引起了人们的广泛关注。

HOPE研究，即心血管健康结果的大型国际研究（Heart Outcomes Prevention Evaluation），是针对高危患者进行的一项旨在评估药物对心血管事件（如心脏病发作和中风）预防作用的研究。

而雷米普利，则是一种常见的抗高血压药物，具有抑制血管紧张素转化酶的作用。

众所周知，血管紧张素是一种在机体内起到调节血压和水平的重要物质。

然而，在一些高风险人群中，过多的血管紧张素会导致血管收缩、血液凝结和炎症反应等，从而进一步加重心血管事件的发生风险。

这时，抑制血管紧张素转化酶就成为了一种预防心血管事件发生的关键药物。

在HOPE研究中，数以千计的高风险患者被纳入进来，并随机分组使用雷米普利或安慰剂。

经过长期的随访观察后，研究结果引人注目。

雷米普利治疗组的患者心脏病发作、中风以及全因死亡率均明显下降。

这表明，雷米普利的应用能够在一定程度上降低高危患者发生心血管事件的风险。

然而，HOPE研究的意义不仅仅在于证实了雷米普利的疗效，更重要的是揭示了抑制血管紧张素转化酶的药物对心血管事件发生的预防作用。

认识到血管紧张素在心血管发病机制中的重要性，使得我们可以从更深层次上挖掘防治心血管疾病的新途径。

从此，许多血管紧张素转化酶抑制剂如ACE抑制剂以及ARB等被应用于临床，取得了显著的疗效。

在新一代抗高血压药物中，抑制血管紧张素转化酶的作用已经成为一项常规的治疗手段，得到了广泛应用。

然而，值得注意的是，如何根据个体的特点进行治疗仍然是一个值得深思的问题。

尽管ACE抑制剂在预防心血管事件方面有着显著的效果，但并非所有人都适合使用这类药物，如孕妇以及患有严重肾脏疾病的患者等。

Ripple-RAID:一种面向连续数据存储的高效能盘阵

Ripple-RAID：一种面向连续数据存储的高效能盘阵孙志卓;张全新;谭毓安;李元章【期刊名称】《软件学报》【年(卷),期】2015(026)007【摘要】视频监控、备份、归档等应用具有独特的负载特性和I/O访问模式,需研究特定的存储节能方法.磁盘阵列的局部并行策略有利于实现该类存储系统的节能,但通常会导致RAID执行小写操作而严重影响性能.为此,提出一种面向该类存储系统的高效能盘阵——Ripple-RAID,采用新的局部并行数据布局,通过综合运用地址转换、异地更新、基于流水技术渐进生成校验、分段数据恢复等策略,在单盘容错条件下,保持了局部并行的节能性,又有效解决了局部并行带来的小写问题.Ripple-RAID具有突出的性能和节能效率,在80％顺序写负载情况下,请求长度为512KB 时,写性能为S-RAID 5的3.9倍,Hibernator、MAID写性能的1.9倍,PARAID、eRAID 5写性能的0.49倍;而比S-RAID 5节能20％,比Hibernator、MAID节能33％,比eRAID 5节能70％,比PARAID节能72％.【总页数】16页(P1824-1839)【作者】孙志卓;张全新;谭毓安;李元章【作者单位】北京理工大学计算机学院,北京 100081;德州学院计算机系,山东德州253000;北京理工大学计算机学院,北京 100081;北京理工大学北京市海量语言信息处理与云计算应用工程技术研究中心,北京 100081;北京理工大学计算机学院,北京 100081;北京理工大学北京市海量语言信息处理与云计算应用工程技术研究中心,北京 100081;北京理工大学计算机学院,北京 100081;北京理工大学北京市海量语言信息处理与云计算应用工程技术研究中心,北京 100081【正文语种】中文【中图分类】TP333【相关文献】1.一种面向智能交通应用的海量空间数据存储及并行处理方法 [J], 李慧彦2.一种面向Hadoop中间数据存储的混合存储系统 [J], 赵南雨;陈莉君3.一种面向FPGA异构计算的高效能KV加速器 [J], 孙征征;兰亚柱;付斌章4.连续数据存储中面向RAID5的写操作优化设计 [J], 孙志卓;张全新;李元章;谭毓安;刘靖宇;马忠梅5.MUSE：一种面向云存储系统的高性能元数据存储引擎 [J], 段翰聪;向小可;吕鹏程因版权原因，仅展示原文概要，查看原文内容请购买。

奈奎斯特定理研究资料

3 数字传输的基本理论无失真传输条件数字基带信号大多数都是矩形波形，尽管平时所见它们的频谱都是有限的，但事实上这只是其频谱图中功率最集中的部分，是近似的结果。

这些基带信号的频谱实际上是在整个频率范围内无限延伸的，如果直接采用矩形波传输，就要求信道的频带是无限的，这在现实中是不可能的，接收到的信号频谱必然与发送端发送信号的频谱不同，产生失真。

对数字基带传输系统进行定量分析可知，如对第K个码元时刻进行抽样，其样值包括三部分：第K个时刻发送波形的抽样值，码间干扰和信道随机噪声干扰。

正是由于后两项的存在，才造成码元误判，引起传输失真。

码间干扰和信道随机噪声干扰与基带系统的传输特性有着密切的关系。

在不考虑信道随机噪声的前提下，接收波形满足抽样值无码间干扰的充要条件是：只在本码元抽样时刻上有最大值，而在其他码元的抽样时刻上抽样值为零。

换句话说，接收波形在其他码元抽样时刻过零点。

在不考虑码间干扰的前提下，误码率随信噪比的提高而下降。

奈奎斯特准则提出：只要信号经过整形后能够在抽样点保持不变，即使其波形已经发生了变化，也能够在抽样判决后恢复原始信号，因为信息完全恢复携带在抽样点幅度上。

奈奎斯特准则要求信号传递过程应满足满足该条件的一个特例为理想低通滤波器，|ω|≤π/T，其他式中，T称为奈奎斯特间隔，T/2是奈奎斯特带宽。

3.1.1 理想低通滤波器简单的模拟低通滤波器SystemView仿真模型如图所示。

其中用图符0来模拟10Hz的脉冲信号源，图符1为有较高抽头数的FIR滤波器来模拟理想的低通滤波器，其通带为5Hz。

系统的时间设置：采样点数为2048，采样频率为100Hz。

各图符的设置如表所示。

理想低通滤波器波形仿真系统设置：Samples= 1000，Samples Rate=100，仿真模型中的图符块参数可按表设置。

表图符块设置参数Token Type Parameters:0 Source: PN Seq Amp = 1 v，Offset = 0 v，Rate = 10 Hz，Levels = 2，Phase = 0 deg，1 Operator: Linear Sys Lowpass FIR，Fc = 5 Hz，Decimate By 1，Quant Bits=None，Taps=511，Ripple= 2，3 Sink: Analysis3.1.2 升余弦滤波器在实际应用中，理想低通滤波器是不可能实现的，因而实际中广泛应用以 /2为中心的，有奇对称的升余弦过度进行整形，称为升余弦滚降整形。

中国文学作品中的“水”隐喻及其英译研究——以《红楼梦》和鲁迅小说为语料

1902022年01期总第597期ENGLISH ON CAMPUS中国文学作品中的“水”隐喻及其英译研究摘　要：概念隐喻存在于日常生活中，在文学作品中也以创新的方式呈现。

本文选取中国文学代表作《红楼梦》以及鲁迅小说，采用汉英平行语料库筛选出的语料, 对汉语文学作品中出现的“水”的概念隐喻及其英译进行研究。

关键词：中国文学作品；水；概念隐喻；英译作者简介：信达，江苏师范大学科文学院。

一、引言隐喻在传统意义上是一种修辞手段，是一种特殊的语言表达方式。

1980年，Lakoff 和Johnson 在《我们赖以生存的隐喻》一书中提出，隐喻是人类语言和思维中的普遍现象，并不仅仅存在于语言中，而是存在于我们的日常生活中和我们的思维中。

认知语言学的体验观认为 :人类的范畴、概念和心智是基于身体经验的 ,其最基本形式主要依赖于对身体部位、空间关系等的感知而逐步形成 ,归根结底 ,认知、意义是基于身体经验的。

实际上，隐喻不仅广泛用于人们的日常生活，还频繁地用在文学作品当中，文学隐喻是日常隐喻的延伸。

日常隐喻的特点是包含上千上万个跨域映射的巨大系统，这个系统同样也被用于文学隐喻。

水不仅是人类赖以生存的物质基础, 而且是人类的精神寄托，水既满足了人类共同的认知体验基础，又在不同文化中承载了不同的文化含义。

以汉语中的“水”隐喻为例，“水”是人类生命的源泉等，这和英语中的“水”隐喻具有共同的根基。

因此，当汉语文学作品的“水”隐喻被译成英文具有一定的研究价值。

本文试图考察以下几个问题：1.中国文学作品中，作者用“水”隐喻哪些事物？2.汉语中的“水”的隐喻在英译本中是否有对应的概念隐喻？3.当汉语中的“水”隐喻和英语中“水”隐喻源域不同时，英译本怎样翻译更有助于读者理解？本文的语料来自绍兴文理学院的《红楼梦》汉英平行语料库和鲁迅小说汉英平行语料库。

二、“水”隐喻的研究现状关于“水”的隐喻，已经有相当一部分学者进行了不同程度的研究。

前提方案PRP和操作性前提方案OPRP介绍

前提方案PRP和操作性前提方案OPRP介绍前提方案（Preliminary Research Plan, PRP）是指在正式研究开始之前所制定的一个计划，旨在明确研究的目标、方法、工作内容以及预期结果等。

它是研究过程中的第一步，提供了实施研究的基本框架。

PRP通常包括以下几个方面的内容：1. 研究目标：明确研究的目的和意义，概括研究所要解决的问题以及所期望的结果。

2. 研究背景：介绍该研究领域的相关背景知识，包括已有的研究成果和存在的问题，以及国内外研究的现状和发展动态。

3. 研究内容和方法：详细阐述研究的内容、范围和方法，包括数据采集和分析的具体步骤，实验设计和调查问卷等工具的使用。

4. 预期结果和意义：说明研究的预期结果和对学术、实践或政策的影响，指出研究可能带来的创新点和进一步研究的方向。

操作性前提方案（Operational Preliminary Plan, OPRP）是在PRP的基础上展开的，更加注重具体实施步骤和时间安排。

OPRP主要包括以下几个方面的内容：1. 研究计划和时间安排：明确研究的具体计划和各项工作任务的时间节点，制定合理的时间表，确保研究进度的可行性。

2. 数据采集和处理方法：具体规划数据采集的方法和来源，并提出数据处理和分析的具体方法和软件工具，保证研究数据的准确性和可靠性。

3. 研究的资源和条件：明确研究所需的人力、物力、财力等资源的配置，并提出合理的利用和保障措施，确保研究的顺利进行。

4. 风险管理和应急措施：提前考虑可能遇到的问题和困难，并制定相应的风险管理和应急措施，以应对不可预见的情况。

通过PRP和OPRP的制定，研究者能够在正式研究开始之前明确研究目标、方法和工作计划，降低研究过程中的风险和不确定性，提高研究的有效性和可操作性。

同时，PRP和OPRP也可以作为研究的框架和指导，使研究者更加有序地进行研究工作，保证研究的顺利进行。

区块链在电子商务领域的应用研究

区块链在电子商务领域的应用研究区块链（Blockchain）作为一种分布式账本技术，近年来在各个领域引起了广泛的关注与研究。

其中，在电子商务领域的应用也逐渐被探索和实践。

本文将从区块链技术的基本原理、电子商务的现状和问题、以及区块链在电子商务领域的应用案例等方面展开，对区块链在电子商务领域的应用进行深入研究。

一、区块链技术的基本原理区块链技术的核心思想是将多个参与者的交易记录按照时间顺序和逻辑顺序连接在一起，形成一个不可篡改的分布式账本。

区块链通过使用密码学技术确保交易的安全性和可信性，并且通过分布式共识机制实现去中心化的管理和容错性。

区块链的特点包括去中心化、透明性、不可篡改以及可追溯性等。

二、电子商务的现状和问题随着互联网的普及和技术的进步，电子商务在全球范围内迅速发展。

然而，电子商务也面临着一些问题。

首先，信任问题是电子商务面临的主要挑战之一。

买家与卖家之间的信任困境导致了虚假交易、欺诈和纠纷等问题的出现。

其次，数据安全和隐私保护也是电子商务领域的重要问题。

传统的数据存储和交换方式存在着被攻击和篡改的风险。

此外，电子商务还面临着中心化管理、高交易费用以及缺乏透明性等问题。

三、区块链在电子商务领域的应用案例1. 供应链管理：区块链可以解决供应链管理中的信任问题。

通过将供应链的各个环节记录在区块链上，实现交易的可追溯性和透明性，可以有效减少供应链中的欺诈和虚假交易，提高供应链的可信度。

例如，Walmart与IBM合作利用区块链技术改进食品供应链管理，在食品安全方面取得了显著成效。

2. 身份验证与权威管理：区块链可以提供去中心化的身份验证和权威管理机制。

通过将身份信息记录在区块链上，可以实现实时验证和防伪功能，防止欺骗和身份盗用。

此外，区块链还可以优化电子商务平台用户管理和身份验证流程，提高用户体验。

3. 交易支付和结算：区块链可以提供去中心化的支付和结算机制，降低交易费用和时间成本。

通过利用智能合约等技术，可以实现自动化的交易支付和结算，提高交易效率和透明度。

波纹效应的名词解释

波纹效应的名词解释波纹效应（Ripple Effect）是一种在许多不同领域产生重要影响的现象。

尽管它的定义可能因应用领域的不同而有所差异，但波纹效应通常指的是某个事件或行动所产生的连锁反应，进而波及其他相关或相邻的事物，并最终造成整个系统或环境的变化。

波纹效应最常见的例子之一是在经济学领域中的金融市场。

当一家公司宣布财报不佳或出现重大危机时，这一事件可能引发投资者的恐慌情绪，导致公司股价暴跌。

随后，其他公司可能受到波及，投资者开始对整个行业感到不安，从而导致整个市场陷入动荡。

类似地，在社会科学中，波纹效应也常常发挥重要作用。

例如，在人际关系中，一次简单的谈话也可以产生波及效应。

一个人的情绪状态和行为会对与之亲近的人产生影响，而被影响的人又可能将这种情绪传递给其他人，形成一种连锁反应。

就像一块平静的湖水被一颗扔入的小石头激起的涟漪一样，这种波纹效应在人际关系中形成了情绪的传播。

波纹效应也可以在自然科学中找到。

例如，气候变化是一个复杂系统，其中许多因素相互作用。

当一个或几个因素发生变化时，可能引发一系列连锁反应，进而导致整个生态系统受到影响。

一些最明显的例子包括全球变暖导致冰川融化、海平面上升以及物种灭绝等不可逆转的变化。

因此，研究波纹效应可以帮助我们更好地理解环境问题，并采取有效措施应对这些问题。

除了经济、社会科学和自然科学之外，波纹效应还可以在其他领域中找到。

例如，在艺术和文化领域中，一部电影或一首歌曲的成功可能会影响整个行业，激励其他艺术家和制片人创作更多类似作品。

类似地，在科技行业，一项创新的技术发明也可能在整个行业产生波及效应，引发其他公司跟进和改进现有产品。

总之，波纹效应是一种在许多领域中普遍存在的现象，它展示了事物之间的相互关系和影响。

这种效应常常具有连锁反应的特点，从而扩散到整个系统或环境中。

波纹效应的理解可以帮助我们更好地预测和解释一些事物发生的原因，并对未来可能发生的变化做出相应的应对措施。

rip实验原理

rip实验原理RIP实验原理是一种分析生物分子在非生物条件下的折叠状态的方法，由美国化学家Daniel L. Purich和丹尼尔罗斯普里奇（Daniel L. Purich）在20世纪80年代开发。

它由一系列化学反应和生物化学反应组成，可提供有关蛋白质折叠和链的结构的精确结果。

RIP实验步骤是这样的：首先，研究者必须将所用的蛋白质以液体形式（通常是蛋白质溶液）加入到化学试管中。

然后，将玻璃漆和半乳糖（用于体外诱导蛋白质折叠）加入到试管中，形成一个分子混合物。

该混合物可以通过温和的加热来进行热处理，使蛋白质在体外环境中折叠/重新折叠。

这个过程需要约30分钟完成。

在折叠完毕后，研究者可以通过使用一种叫做质谱分析的技术来检查蛋白质折叠的结果。

质谱分析是一项分析技术，可以使研究者了解蛋白质折叠所形成的结构。

这项技术可以提供关于这些结构的蛋白质分子量、肽段长度和折叠形状的信息。

使用精确的RIP实验原理可以提供有关蛋白质折叠的更多信息。

它可以帮助研究者了解蛋白质折叠状况，以及折叠过程中可能发生的其他变化。

它也可以帮助研究者识别和分析折叠蛋白质和未折叠蛋白质之间的区别，从而有助于了解蛋白质折叠对蛋白质功能的影响。

此外，RIP实验原理还可以帮助研究者进行蛋白质的结构分析。

这种分析可以显示蛋白质折叠后所形成的结构，以及蛋白质折叠状态的最终形态。

这可以为研究者提供有关蛋白质的结构和功能的更多信息，从而有助于他们更好地理解蛋白质的行为。

总而言之，RIP实验原理是一项重要的研究工具，可以为研究者提供有关蛋白质结构和折叠状态的信息。

RIP实验原理可以用来检测不同的蛋白质结构，并可以帮助研究者了解蛋白质折叠过程的机制，从而更好地了解蛋白质的功能。

它可以帮助研究者更深入地了解蛋白质结构和功能之间的关系，从而推动未来药物研究和发展。

超宽带认知无线电的关键技术研究

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宽带无线
Broadband Wireless
超宽带认知无线电的关键技术研究
■ 北京邮电大学无线网络实验室仲玮国家无线电监测中心曾繁声张陆勇
和通信方面具有充分的计算智能来探测用户通信需求，并根据这些需求来提供最适合的无线电资源和无线业务。”认知无线电的两个最主要目标是高度可靠的通信方式以及高效的频谱利用率。
1.2 超宽带（UWB）
超宽带技术自上世纪90年代起应用于民用领域后，在国际上掀起了一股研究热潮，被认为是下一代无线通信的革命性技术。超宽带是指信号的-10d B 相对带宽大于0.20或绝对带宽超过500M H z的通信系统。U W B的这个定义并没有限定它的数据信号的具
2.3 基于MB-OFDM的适配信号
正交频分复用(O F D M)是一种能够有效地在严重的多径衰落信道中进行高速数据传输的技术。它可以有效地克服多径带来的符号间干扰(I S I)；通过各个子载波的联合编码，O F D M具有很强的抗衰能力。因为具备这些优点，基于多频带正交频分复用(M BO F D M)的U W B系统在I E E E802.15.3a中和I R-U W B系统一样都被提案为候选标准。同时M B-O F D M技术能够检测第一用户和比较容易地对频谱进行整形从而降低对第一用户的干扰，因此，它也是实现超宽带认知无线电的一项重要技术。由于M B-O F D M系统在频域里产生传输信号，因此它能够通过关闭通道的方式来整形传输频谱。该系统在频域中产生凹槽(Notch)的一个著名方法就是把与受害者频带(Victim Band)，比如无线电天文频段，重叠的几个子通道关闭掉，被关闭的子通道称作零通道(Zero Tone)。这种方法的优点是接收机不

化学分析的新方法和技术

化学分析的新方法和技术化学分析是一项非常重要的科学研究。

它可以帮助我们了解物质的组成和性质，还可以帮助我们解决许多实际问题。

但是，传统的化学分析方法和技术有很多限制。

比如说，有些物质很难或者不可能通过传统的化学方法进行分析，有些方法需要的时间、费用和设备也很高。

因此，为了解决这些问题，科学家们一直在研究和开发新的化学分析方法和技术。

本文将介绍一些当前正在使用或者开发中的新方法和技术。

1. 微波消解-电感耦合等离子体质谱 (Microwave digestion-Inductively coupled plasma mass spectrometry, MD-ICP-MS)MD-ICP-MS是一种将微波消解和电感耦合等离子体质谱结合起来的化学分析方法。

微波消解是一种利用微波辐射加热样品并在酸性体系中进行分解的方法，可以将样品中的有机和无机物完全消解。

而ICP-MS则是一种高灵敏度的元素分析方法，可以检测微量元素的含量。

MD-ICP-MS将这两种方法结合在一起，可以实现快速、高效、准确地分析样品中的多种元素。

2. 涟漪流动组织振荡微泵 (Ripplesome flow tissue oscillatory pump, RFTOP)RFTOP是一种由纳米流体控制技术驱动的微泵，可以快速、无损地提取样品中的蛋白质、DNA等生物分子。

这项技术通过与样品中的生物分子发生特异性作用，实现了高效、准确的样品提取和分析。

3. 电导机理感应耦合等离子体质谱 (Electrochemical coupling inductively coupled plasma mass spectrometry, EChemICP-MS)EChemICP-MS是一种基于电化学方法和ICP-MS的结合分析技术。

传统上，ICP-MS需要对样品进行化学预处理，以提取目标元素进行分析。

而EChemICP-MS采用电化学方法直接将目标元素在液体体系中氧化或还原成具有良好的挥发性的化合物，再通过ICP-MS进行检测和定量分析。

RIP结果pcr分析

RIP结果pcr分析Real-time qPCR就是在PCR扩增过程中，通过荧光信号，对PCR进程进行实时检测。

由于在PCR扩增的指数时期，模板的Ct值和该模板的起始拷贝数存在线性关系，所以成为定量的依据。

由于常规的PCR的缺点，real-time qPCR由于其操作简便，灵敏度高，重复性好等优点发展非常迅速。

设在已经涉及到生命科学研究的各个领域，比如基因的差异表达分析，SNP检测，等位基因的检测，药物开发，临床诊断，转基因研究等。

我想做过qPCR的研究者用过的仪器也无怪乎ABI7000、7300、7500,7700、7900НТ、Step OnePlus、StepOne、PRISM StepOne 系列；BIO-RAD的CFX96、iCycler iQ5、MyiQ、MJ Research Chromo4 Opticon系列；Stratagene Mx系列；Roche LightCycler 系列；Eppendorf Maser cycler;Corbett Rotor-Gene;Cepheid SmartCycler”和BIOER的LineGene系列。

其仪器的设置和数据输出方式基本类似，相差不大。

有过qPCR实验经验的研究者可能很快就能熟遇Ct值，以及数据的常用运算方法比较Ct方法那么这个数据到底有没有统计意义呢？这个该如何分析？我们来逐渐了解相对定量qPCR的数据统计分析。

首先在数据分析之前，要确保数据的准确性，也就是实验过程的各个部门都要严格操作，也就是MIQE标准（具体可见Bustin SA et at Clin Chem 55,611-622 2009）。

这些都做到了，那么就可以来分析Ct数据了。

统计分析，至少有3个数据才可以。

那就是在设计实验中，每组至少有3个生物学重复（也就是3个不同的样本）。

这个和qP CR的3个PCRreplicate是完全不同的概念（这儿是同一个样本的3个重复）。

人工神经网络与神经网络优化算法

其中P为样本数，t j, p 为第p个样本的第j个输
出分量。
感知器网络
1、感知器模型 2、学习训练算法 3、学习算法的收敛性 4.例题
感知器神经元模型
感知器模型如图Fig2.2.1 I/O关系
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图2.2.1
单层感知器模型如图2.2.2
定义加权系数
10.1 人工神经网络与神经网络优化算法
③第 l 1层第 i个单元到第个单元的权值表为
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, 其中 i0 f (•)为隐单元激励函数,
人工神经网络与神经网络优化算法
自20世纪80年代中期以来, 世界上许多国家掀起了神经网络的研究热潮, 可以说神经网络已成为国际上的一个研究热点。
1.构成
生物神经网
枝蔓（Dendrite）
胞体(Soma)
轴突（Axon）胞体(Soma)
2.工作过程
突触（Synapse）
生物神经网
3.六个基本特征： 1）神经元及其联接； 2）神经元之间的联接强度决定信号传递的强
函数的饱和值为0和1。
4.S形函数
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c=a+b/2
(0,c)
net
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2.2.3 M-P模型
McCulloch—Pitts（M—P）模型, 也称为处理单元（PE）
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