CompetitionCLARiiONAX4
GAM 零回波与机器人扁平减速器说明书
Z e r o-B a c k l a s h&R o b o t i c F l a n g e G e a r R e d u c e r sGPL Planetary Robotic Gearbox• The new standard in zero-backlash (≤6 arcsec)• 10x better than other zero-backlash gearboxes• High positional accuracy without vibration• See page 12 for more informationGCL Cycloidal Robotic Gearbox• Backlash ≤1 arcmin• Impact resistance 5x nominal torque• Integral pre-stage available• See page 26 for more informationGSL Strain Wave Robotic Gearbox• Backlash ≤ 0 .5 arcmin• Strain wave (harmonic) gearing for zero-backlash and high torque• Simple design in small, lightweight gearbox• See page 40 for more informationEPL SPH GCL GSL GPLG P L S e r i e s R o b o t i c P l a n e t a r y G e a r b o x e sFeaturesBenefitsZero Backlash ≤ 0.1 arcmin Highest precision for your application Lowest lost motion ≤ 0.6 arcmin High torsional rigiditySuperior accuracy even with low torquePatented self-adjusting backlash system Constant precision throughout the entire lifetime High torque density 58-73 Nm/kg Smaller gearbox, lighter overall system Fully-loaded life 20,000 operating hours Longer lifetime, reduced maintenance costs Efficiency > 90%Lower power consumption, smaller motor Quiet < 70 dBReduced workplace noise exposure High output, acceleration and emergency stop torqueMore security for your application Superior tilting and torsional stiffness Allows precise positioning Low vibrationHigh repeatabilityLowest breakaway torque Better control of the overall system Standard mineral oil Reduced lubrication costLow operating temperature Longer component and lubricant life Low moment of inertia Excellent dynamic performance Compact design, low weightLighter overall design Input with Integrated motor adapter and clampReady to mount your motorRobotic Planetary GearboxesGAM’s GPL Series Robotic Planetary Gearboxes provide the lowest backlash and high tilting rigidity for horizontal and vertical robotic and motion control applications .• With a backlash of ≤ 0.1 arcmin, the GPL Series can be considered a zero backlash gearbox• Best-in-the-market torsional rigidity for ≤ 0.6 arcmin lost motion • Patented design guarantees the backlash will not increase over the life time of the gearbox• Industry-accepted proven performance• Seven sizes with nominal output torque of 445 to 3505 Nm and ratios of 50:1 to 200:1• Flanged solid shaft output or flanged hollow shaft output (up to 75 mm through hole)• Integrated motor adapter plate ready to mount your motor • GPR with right angle input available - contact GAMWith seven sizes, two output options, and ratios up to 200:1, there is a GPL for your application .Integrated helical input stage for high input ratios and high input speedsPlanetary 2nd stageConical Spur Gear Zero-backlash 3rd stageMain Bearingsupports high external loadsGround gears for lowestbacklash with high repeatability, low noise and high transmission accuracyOutput flange for high torsional and tilting stiffnessApplicationsThe GPL Series can be used in a variety of applications where zero-backlash, high tilting and tor-sional rigidity, and long life are required. With the large output mounting flange, through-hole op -tion, and servo-ready mount, the GPL is ideal for many robotic and motion control applications:• Robots• Handling systems • T ool changers • Positioning• Rack & pinion • Pick & place • T urntables• and many moreIndustriesThe GPL Series is ideal for many industries including:• Robotics • Automation • Packaging Machines • Machine tool builders • T urntables• Printing industry• Welding Systems • Medical • Navigation • and many morewith GPL Planetary Gearbox in the baseurntableG P L S e r i e s R o b o t i c P l a n e t a r y G e a r b o x e sGPL-HG P L -FG P L -056 D i m e n s i o n sGPL-F-056GPL-H-056depending on motordepending on motorG P L -112 D i m e n s i o n sGPL-F-112GPL-H-112depending on motordepending on motorG P L -224 D i m e n s i o n sGPL-F-224GPL-H-224*Dimension may vary depending on motordepending on motorG P L -400 D i m e n s i o n sGPL-F-400GPL-H-400depending on motordepending on motorG C L S e r i e s R o b o t i c C y c l o i d a l G e a r b o x esRobotic Cycloidal GearboxesGAM’s GCL Series Robotic Cycloidal Gearboxes provide low backlash and high rigidity for horizontal and vertical robotic and motion control applications .• Backlash of ≤1 arcmin with lost motion of ≤1 arcmin• Withstands the frequent start-stop impact loads of industrial robots with impact resistance 5x nominal torque • Multi-tooth meshing for torsional rigidity • Planetary gear for input speed reduction• Flange output in 7 sizes with nominal output torque of 167 to 4410 Nm and ratios of 57:1 to 192 .4:1• Flanged hollow output in 6 sizes (up to 138 mm through hole) with nominal output torque of 490 to 4900 Nm • Drops in for many competitors’ products•Integrated motor adapter plate ready to mount your motor11234657GCLC-F GCLC-H GCL-F IntegratedG C L C -F / G C L -F160320*320400G C L C -F / G C L -F G e a r b o x D i m e n s i o n sGCLC-F-020GCLC-F-080G C L C -F / G C L -F G e a r b o x D i m e n s i o n sGCLC-F-160G C L C -F / G C L -F G e a r b o x D i m e n s i o n sFor more information, call us toll-free at 888-GAM-7117 | Visit for 2-D and 3-D Drawings36GCLC-H-050G C L -H G e a r b o x D i m e n s i o nsGCLC-H-120For more information, call us toll-free at 888-GAM-7117 | Visit for 2-D and 3-D Drawings38GCLC-H-400mating componentGCLC-H-500G C L -H G e a r b o x D i m e n s i o n sInput: Pinion O utput: Flange Fixed: Housing Ratio: RInput: Pinion O utput: Housing Fixed: Flange Ratio: R-1HousingPinion Shaft FlangeInput: Pinion O utput: Flange Fixed: Housing Ratio: RInput: Pinion O utput: Housing Fixed: Flange Ratio: R-1HousingPinion Shaft FlangeRobotic Strain Wave GearboxesGAM’s GSL Series Robotic Strain Wave Gearboxes provide zero-backlash and high torque in a small, lighweight gearbox .• Backlash of ≤0.5 arcmin (≤30 arcsec)• High repeatability and positional accuracy for fine positioning • High reduction ratios in a single stage: 50:1 to 160:1• Simple design for integration into housing or machine • High torque density with low inertia• Drops in for popular competitor gearboxesStrain Wave Operating PrincipleS train wave gear reducers have three basic components:Wave GeneratorMade up of an elliptical cam and a ball bearing. It is usually attached to the driving component. The inner ring of the bearing is fixed around the cam causing the bearing to deform to an elliptical shape.transmitting torque. Most commonly the output component Circular SplineRigid steel ring with internal teeth. It has 2 more teeth than the flexspline. Most commonly the fixed component.Operation1. The W ave Generator mounts inside the Flexspline forcing the Flexspline into an elliptical shape.2. The Flexspline teeth engage the Circular Spline teeth along the major axis of the ellipse of theWave Generator. The Flexspline has two fewer teeth than the Circular Spline.3. The rotation of the Wave Generator continuously deforms the Flexspline resulting in the teeth engaging and disengaging the teeth of the Circular Spline, rotating the Flexspline in theopposite direction4.As the Wave Generator moves through 360°, since the Flexspline has two fewer teeth it “runsout” of teeth to engage with the Circular Spline before it gets to the first tooth and so moves two teeth in the opposite direction of the Wave Generator. 5. The distance (degrees) the Flexspline rotates depends on the reduction ratio: at 50:1 it moves360/50 or 7.2°At Input 0°: Output at 0°At Input 90° rotation clockwise: Output has rotated ½ tooth counter-clockwiseAt Input 360° rotation clockwise: Output has rotated 2 teeth counter-clockwiseG S L S t r a i n W a v e R o b o t i c G e a r b o x• Low Profile• Small diameterGSL-CS-A/BGSL-HT GSL-HS-A/BGSL-HS-CGSL-HS-D GSL-HS-EG S L G e a r b o x M o d e l sGSL-HS-A/BGSL-HS-DGSL-HTG S L G e a r b o x T e c h n i c a l S p e c i f i c a t i o n sG S L -C S -A G e a r b oxGSL-CS-A• Keyed or set screw input • Cup-style flexspline • Frame sizes 014-032G S L -C S -B G e a r b oxGSL-CS-B• Keyed or set screw input• Oldham’s coupling accomodates slight parallel misalignment • Cup-style flexspline • Frame sizes 014-032For more information, call us toll-free at 888-GAM-7117 | Visit for 2-D and 3-D Drawings50GSL-HS-A• Keyed or set screw input • Hat-style flexspline • Frame sizes 014-032For more information, call us toll-free at 888-GAM-7117 | Visit for 2-D and 3-D Drawings52GSL-HS-B• Keyed or set screw input• Oldham’s coupling accomodates slight parallel misalignment • Hat-style flexspline • Frame sizes 014-032For more information, call us toll-free at 888-GAM-7117 | Visit for 2-D and 3-D Drawings54GSL-HS-C• Hollow shaft input • Hat-style flexspline • Frame sizes 014-040For more information, call us toll-free at 888-GAM-7117 | Visit for 2-D and 3-D Drawings56GSL-HS-D • S haft input• Hat-style flexspline • Frame sizes 014-032For more information, call us toll-free at 888-GAM-7117 | Visit for 2-D and 3-D Drawings58GSL-HS-E• Includes output bearing but no housing for more complete integration where other GSL gearboxes don’t fit • Hollow shaft input • Hat-style flexspline • Frame sizes 014-032。
治疗癌症的联合疗法[发明专利]
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专利名称：治疗癌症的联合疗法
专利类型：发明专利
发明人：G·斯格罗斯,V·M·利驰昂,P·A·马克斯,R·A·利福坎德申请号：CN03813849.2
申请日：20030415
公开号：CN1728991A
公开日：
20060201
专利内容由知识产权出版社提供
摘要：本发明涉及治疗需要治疗的患者癌症的方法。
该方法包含对需要治疗的患者在第一治疗程序中给以第一量组蛋白脱乙酰酶抑制剂，在第二治疗程序中给以第二量或剂量放射。
第一与第二治疗一起构成治疗有效量。
HDAC抑制剂与放射疗法的组合在治疗上是有协同性的。
申请人：斯隆-凯特林癌症研究院
地址：美国纽约
国籍：US
代理机构：中国国际贸易促进委员会专利商标事务所
代理人：赵艳华
更多信息请下载全文后查看。
Fronts propagating with curvature dependent speed Algorithms Based on Hamilton-Jacobi Formulations
reaching out into the unburnt gas somehow propagate slower than do concave regions which are hot gases surrounding a small unburnt pocket. At the same time, particles along the flame front undergo an increase in volume as they burn, creating a jump in velocity across the flame front. This discontinuity in the velocity field creates vorticity along the burning flame, which can be related to the local curvature, and this new vorticity field contributes to the advection of the propagating flame. Thus, there are at least two distinct ways in which the speed of the moving flame depends on the local curvature. Typically, there have been two types of numerical algorithms employed in the solution of such problems. The first parameterizes the moving front by some variable and discretizes this parameterization into a set of marker points [39]. The positions of the marker points are updated in time according to approximations to the equations of motion. Such techniques can be extremely accurate in the attempt to follow the motions of small perturbations. However, for large, complex motion, several problems soon occur. First, marker particles come together in regions where the curvature of the propagating front builds, causing numerical instability unless a regridding technique is employed. The regridding mechanism usually contains a error term which resembles diffusion and dominates the real effects of curvature under analysis. Secondly, such methods suffer from topological problems; when two regions "burn" together to form a single one, ad-hoc techniques to eliminate parts of the boundary are required to make the algorithm work. Other algorithms commonly employed fall under the category of "volume of fluid " techniques, which, rather than track the boundary of the propagating front, track the motion of the interior region. An example of this type of algorithm is SLIC [26]. In these algorithms, the interior is discretized, usually by employing a grid on the domain and assigning to each cell a "volume fraction" corresponding to the amount of interior fluid currently located in that cell. An advantage of such techniques is that no new computational elements are required as the calculation progresses (unlike the parameterization methods), and complicated topological boundaries are easily handled, see [4,32]. Unfortunately, it is difficult to calculate the curvature of the front from such a representa-
Short Course for Qualcomm -- Analysis and Design of LC VCOs -- by B Razavi 2010 [good]
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Analysis and Design of LC VCOs
April 19, 2010
Behzad Razavi Electrical Engineering Department University of California, Los Angeles
33
Analysis of Phase Noise
Need to answer these questions: • • How does noise injected by a device corrupts the phase? How much noise does each device inject? Tens of papers have been published on phase noise in oscillators. Many mechanisms result in phase noise. No single approach has been sufficient to give insight into all mechanisms. We follow two approaches here: - Approach I: based on time averages (a) the average spectrum of noise of a device while the noise spectrum varies with time. (b) the “average resistance” - Approach II: based on phase response of an oscillator to an injected impulse in the time domain [Hajimiri & Lee, JSSC, Feb. 98].
2024数学建模美赛c题
2024数学建模美赛c题
2024年美国大学生数学建模竞赛C题是关于网球中的动量的问题。
该题目
要求参赛者探讨网球中的动量，以及动量如何影响网球的弹跳和飞行。
该题目提供了一些数据，包括不同速度和重量的网球的弹跳高度和飞行距离。
参赛者需要使用这些数据来建立数学模型，以解释动量如何影响网球的弹跳和飞行。
在建立模型的过程中，可以使用不同的数学工具和软件，例如Python、Matlab、Excel等。
在解释数据时，可以使用回归分析、统计分析、机器学习等方法。
最后，参赛者需要将建立的模型应用于实际情境中，例如在网球比赛中如何使用动量来提高击球效果。
同时，还需要回答题目中提出的问题，例如“为什么动量对网球的弹跳和飞行有影响？”、“如何利用动量来提高网球比赛的表现？”等。
总之，2024年美国大学生数学建模竞赛C题是一个有趣且具有挑战性的问题，需要参赛者具备扎实的数学基础和良好的数据分析能力。
约翰·克兰 Metastream T 系列联轴器 - 产品说明说明书
John Crane’s Metastream T Series couplings incorporate scalloped, stainless-steel, flexible membranes. This design gives the most flexible solution for high-torque and misalignment conditions. This range ofcouplings has been specifically designed to meet the exacting standards of API 610 (ISO 13709), ISO 14691 and API 671 (ISO 10441), with exceptions.The coupling is available as a cartridge design to maximize reliability, and increase ease of installation on site. This concept ensures the high level of integral balance is maintained when the coupling is installed.The T Series range incorporates many features listed as standard to ensure safe and trouble-free operation. This gives the user that fit-and-forget reliability expected of all John Crane’s Metastream couplings.• Easy to fit• M eets API 610 (ISO 13709) and ISO 14691. Can be supplied to API 671 (ISO 10441), with exceptions.• Intrinsic balance exceeds AGMA class 9• I deally suited to pump applications; electric motor and turbine drives in critical process industry; marine and power generation applications • Coated carbon steel for corrosion protection • Choice of hub configuration to suit shaft diameters • ATEX compliant• Coupling constructions available for -55°C to 150°CDesign Features• F it and forget - Designed for infinite life and, with correct machinery alignment, will often outlast the machines it connects• O verload protection - Fitted with overload collars to prevent flexible membrane rupture in the event of severe torsional overload• A nti-fly retention - Specifically designed anti-fly guard rings to ensure safe operation, even in the unlikely event of flexible membrane and bolt failure• L ow imposed loads - Designed to optimize torque capability while minimizing reaction forces due to misalignment, thus maximizing the life of the machines connected• Z ero maintenance - Requires no lubrication or routine maintenance • S tandard features:–API 610 compliant puller holes –Self-locking features ensure hub boltsremain in place under all vibration conditions–Compression bolt features ease installationand removal of transmission unit•N o backlash - Torsionally stiff design ensures there is zero backlash, making coupling ideal for drives where constant speed is crucialA – S tainless steelflexible membranes B – O verload collars C – C artridgetransmission unit D – Anti-fly feature E – A nti-corrosiontreatment F – H ubs with APIpuller holes G – R obust hub bolt H – L arge shaftdiameters accommodated I – S elf-lockingthreadJ – C ompressionbolt featureTSK Dimensional Data (Millimeters)Notes:1. Maximum bores shown are based on standard BS/AGMA rectangular/square keys. Unless otherwise specified, parallel bores will be machined to an IT 7 tolerance, with Js9 key-ways to DIN 6885, BS 4235 or BS 46 Pt1 (in.).2. These DBSE sizes are more readily available. Other lengths to suit specific shaft separations are available on request.3. The coupling sizes shaded are non-preferred, and TLK couplings should be selected whenever possible.4. Dimensions should not be used for construction. Certified dimensions furnished upon request.Note:1. Coupling size 0014 is a 4-link coupling with coupling designation TDKS-0014.2. For complete coupling weight, weights of two appropriate hubs plus a transmission unit are required.3. Hubs will be supplied unbored, unless specified. Contact your local sales office regarding standard bore and keyway tolerances.4. Coupling sizes shaded are non-preferred, and TLK coupling should be selected whenever possible.TSK Typical ArrangementStandard Hub Large HubExtended HubABCGHGDJEFAvailable Options1. Select appropriate service factor (SF) from table below.2. Calculate the coupling rating (R) from:R = kW x 1,000 x SFNWhere:kW = rated power for drive equipment (kW)N = speed (rpm)3. Select a coupling with the same or higher rating.4. Check the hub bore capacity is suitable. If not, select a large hub or a larger size coupling.5. Check peak torque capability is suitable for application.6. Check speed capability is suitable.7. Check whether additional dynamic balancing is required.8. Specify distance between shaft ends (DBSE).Example:900 kW electric motor connected to a centrifugal pump at 1,500 rpm with a 180 mm DBSE SF = 1.0R = 900 x 1,000 x 1.0 1500R = 600 kW per 1,000 rpmSelection: TLKS – 0750Standard hub bore up to 110 mm Large hub bore up to 148 mm Peak torque capability – 14 kNmAdditional balancing should not be required.• S park-resistant couplings for hazardous zone operation• S pecial materials for low-temperature applications and/or higher corrosion resistance • E lectrical insulation • A djustable shims for taper shafts • A xially rigid construction • T orque limiting and shear pin designsConsult John Crane for any other special requirements. John Crane couplings can be adapted to suit virtually all power transmission coupling needs.Suggested service factors for electric motor, steam turbine and gas turbinedrivers are given below.* U se a minimum service factor of 1.25 on electric motor drives through a gearbox.*Use a minimum service factor of 1.75 on electric motor drives with VFD coupled to high inertia driven machines.The examples given are for typical machines and are empirically basedguidelines. Knowledge of actual torque characteristics may indicate a different service factor. Consult John Crane for advice.Kselect is an internet-based selection program for the TSK/TLK.This selection program provides all necessary technical data, including inertias and torsional stiffness.Visit to access this program.Max Speed(1) Weight – Transmission Unit(1)(2) Weight - Unbored Hub Coupling SizeRating Max.Continuous Torque Peak Overload Torque Standard Hub Large Hub Abs. MinimumDBSEPer meter extra DBSE Standard (3) Large Balanced Unbalanced Unbalanced kW/1,000rpmkNmkNmrpm rpmrpmkgkgkgkg0300300 2.9 5.715,3005,70011,3008.616.2819.10500500 4.89.612,8005,00010,10013.621.713.730.907507507.21411,3004,6009,00019.527.219.341.810501,0501020.110,1004,2009,00027.93431.141.815001,5001428.79,0003,9008,20037.541.842.253.720002,0001938.28,2003,7007,40049495470.926002,6002549.77,4003,400—666071—33503,3503264.06,9003,200—8068101—42504,2504181.26,3003,000—10581135—60106,010571155,6002,850—147101189—85008,500811625,0002,500—212132269—901313,0001242484,2002,200—340169406—901717,0001623253,8002,050—454203709—902121,0002014013,6001,950—547234873—903636,0003446883,0501,750—8673281,423—904949,0004689362,8001,600—1,1534031,934—Notes:1. For a complete coupling, weights of two appropriate hubs plus a transmission unit are required.2. Hubs will be supplied unbored unless specified. Contact your local sales office regarding standard bore and keyway tolerances.3. Additional weight of extended guard ring is included.(1) C (Max)(1) F (Max)GHJ(2) K - DBSELCoupling SizeABRect. Key (BS 4235)Sq. Key (AGMAB04)DERect. Key (BS 4235)Sq. Key (AGMAB04)Min. mm7 in.180 mm 250 mmPreferred Absolute 140 mm300155116827610614311010220916184130117X X X X 11050018514310095127167134127235187100148130—X X X 134750209161110102143185148139262208110169146—X X X 1481050235187134127167185148139262208134183161—X X X 1481500262208148139185200161152288225148207179———X 1612000288225161152200229184172318255161229197———X 1662600318255184172229———166241210———X —3350342286212197257———191255221———X —4250371315235219285———212273244———X —6010417354260242320———234303269—————8500465402290280365———261345311—————9013529464330318424———297381346—————9017611546420381503———378422387—————9021653588446419538———401457416—————9036761696520483632———468533496—————9049834769580546695———522587552—————Notes:1. Maximum bores shown are based on standard BS/AGMA rectangular/square keys. Unless otherwise specified, parallel bores will be machined to an IT 7 tolerance, with Js9 key-ways to DIN 6885, BS 4235 or BS 46 Pt1 (in.).2. These DBSE sizes are more readily available. Other lengths to suit specific shaft separations are available on request.3. Dimensions should not be used for construction. Certified dimensions furnished upon request.HUB HUBBalance ConditionThese couplings are designed with a high inherent balance, due to the precision of the manufacturing process. It is important that all parts are carefully stored and fitted to maintain this integrity.The inherent balance of the T Series meets AGMA standard 9000-D11 class 9. The adjacent chart relates the T series rating to operating speeds on the basis of the AGMA class 9 characteristic to provide a general guide to determine if dynamic balance improvement is necessary.When balancing improvement is requested, John Crane will dynamically balance the transmission unit. Hubs may also be dynamically balanced, and this will be carried out after machining the bore but before cutting single keyways.Correct alignment of shafts is essential for reliable machinery performance.The angular and axial restoring forces in the table below are given at maximum deflections. The chart can be used to determine forces across the full deflection range. The nonlinear characteristics of axial stiffnesscan dampen a system to prevent high-amplitude axial vibration.Notes:1. Meets NEMA end float specification without modification.2. Maximum angular misalignment will reduce with rotational velocity in excess of 3600 rpm (only on sizes 0500 to 1400).3. Maximum angular misalignment will be 50% at the maximum axial, and vice-versa.4. V alues based on preferred min DBSE and maximum angular misalignment. Greeter parallel offset is achievable by increasing the DBSE.5. The coupling sizes shaded are non-preferred, and TLK couplings should be selected whenever possible.If the products featured will be used in a potentially dangerous and/or hazardous process, your John Crane representative should be consulted prior to their selection and use. In the interest of continuous development, John Crane Companies reserve the right to alter designs and specifications without prior notice. It is dangerous to smoke while handling products made from PTFE. Old and new PTFE products must not be incinerated. ISO 9001 and ISO 14001 Certified, details available on request.©2020 John Crane Revised 3/20 TD-TSK/TLKEuropeUnited Kingdom Tel: 44-1753-224000 Fax: 44-1753-224224North AmericaUnited States of America Tel: 1-847-967-2400 Fax: 1-847-967-3915Latin America BrazilTel: 55-11-3371-2500 Fax: 55-11-3371-2599Middle East & Africa United Arab Emirates Tel: 971-481-27800 Fax: 971-488-62830Asia Pacific SingaporeTel: 65-6518-1800 Fax: 65-6518-1803。
2024年美赛c题的解题思路
2024年美赛c题的解题思路
美赛C题是数据分析和挖掘问题，需要使用数据分析和挖掘的方法来解答。
解题思路如下：
1. 数据清洗：首先需要对数据进行清洗，去除重复、异常和不相关的数据，并对缺失值进行处理。
可以使用Python中的pandas库来完成这些操作。
2. 数据探索：在数据清洗之后，需要对数据进行探索，了解数据的分布和特征。
可以使用Python中的matplotlib和seaborn库来进行可视化分析。
3. 特征工程：根据问题的需求，对数据进行特征工程，提取出与问题相关的特征。
可以使用Python中的sklearn库来进行特征工程。
4. 模型训练：根据问题的类型，选择合适的模型进行训练。
如果是分类问题，可以选择决策树、随机森林、支持向量机等分类模型；如果是回归问题，可以选择线性回归、决策树回归等回归模型。
可以使用Python中的sklearn
库来进行模型训练。
5. 模型评估：对训练好的模型进行评估，可以使用交叉验证、准确率、召回率、F1值等指标来评估模型的性能。
6. 优化和调整：根据模型评估的结果，对模型进行优化和调整，提高模型的性能。
7. 结果呈现：将最终的结果呈现出来，可以使用表格、图表等形式来展示结果。
以上是解答美赛C题的一般思路，具体解题过程需要根据问题的具体情况来进行调整。
非平均化自适应Catmull-Clark细分算法
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郑津津 朱 巍 周洪军 沈连嬉
（ 国科 学 技 术 大 学精 密机 械 与 精 密 仪 器 系 安 徽 合肥 ２０ ２ ） 中 ３ ０ ７
（ 国家同步辐射实验室
安徽 合肥 ２０ ２ ） ３０ ９
摘
要
提 出一种基于 网格边 的光滑度 算来进行 Ｃ ｔｕｌ ｌ ｋ自适应细分 的新算法。该 方法能够在 满足显 示需求的前提 下较 ａ ｌＣａ ｍ — ｒ
好地减小细分 曲面过程 中的网格 生成数 ， 同时解决 了由于采用 网格 顶点 曲率计算 ， 来实现 自适 应细分 方法中平均化生成顶点曲率带 来的不足。通过对比试验 ， 算法能更好地 区别 当前细分 网格 中光滑与非光滑 区域 ， 增加对非光滑 区域 网格加 密密度 ， 并且该算法 能 够普遍适用于较复杂的细分模 式中， 有一定 的推广价值。 具
（ ｅａｔ ｅｔｆＰｅｉｏ ｃｉｅ ｎ ｒ ｉｏ ｓ ｕ ｅｔｔ ｎ Ｕ ｉｒｔ ＆ ｎ ｅ ｎ ｌ ｙｏ Ｃ ｉａ Ｈｆｉ ３ ０ ７Ａ ｈｉＣ ｉａ Ｄｐ ｒ ｎ ｏ ｒ ｓ ｎＭａｈｎｒ ａｄＰｅｓ ｎＩ ｔ ｍ ｎａｉ ， ｎ ｅｓｙｏ ｍ ｃｉ ｙ ｃｉ ｎｒ ｏ ｖ ｉｆ Ｍｅａ ｄＴｃ ｏｏ ｈｎ ， ｅ ０ ２ ，ｎ ｕ，ｈｎ ） ｈ ｇｆ ｅ２ （ ａｉ ａ ｙｗ ｒ ｒ ａ ｉｉｎＬ ｂｒｔｒ， ｅ ｉ ３ ０９，ｎ ｕ，ｈｎ ） Ｎ ｔｎ ｌ ｖ ｈｏ ｏ Ｒ ｄａ ｏ ａｏａｏｙ Ｈｆ ０ ２ Ａ ｈｉＣ ｉａ ｏ Ｓ ｔｎ ｔ ｅ２
Quality competition versus price competition goods- An empirical classification
NBER WORKING PAPER SERIESQUALITY COMPETITION VERSUS PRICE COMPETITION GOODS:AN EMPIRICAL CLASSIFICATIONRichard E. BaldwinTadashi ItoWorking Paper 14305/papers/w14305NATIONAL BUREAU OF ECONOMIC RESEARCH1050 Massachusetts AvenueCambridge, MA 02138September 2008The views expressed herein are those of the author(s) and do not necessarily reflect the views of the National Bureau of Economic Research.NBER working papers are circulated for discussion and comment purposes. They have not been peer-reviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications.© 2008 by Richard E. Baldwin and Tadashi Ito. All rights reserved. Short sections of text, not to exceed two paragraphs, may be quoted without explicit permission provided that full credit, including © notice,Quality competition versus price competition goods: An empirical classificationRichard E. Baldwin and Tadashi ItoNBER Working Paper No. 14305September 2008, Revised October 2008JEL No. F14ABSTRACTBased on the recent trade models of the Heterogeneous Firms Trade (HFT) model and the Quality Heterogeneous Firms Trade (QHFT) model, we classify export goods (at the HS 6-digit level of disaggregation) by quality and price competition. We find a high proportions of quality-competition goods for the major EU countries and lower proportions for Canada, Australia and China. However, the overlap of these quality-competition goods is not large, which suggests that characteristics of export goods are substantially different across countries at the same HS 6-digit code.Richard E. BaldwinGraduate Institute, GenevaCigale 2Lausanne Switzerland 1010and NBERbaldwin@graduateinstitute.chTadashi ItoGraduate Institute, Geneva11 a Ave de la PaixGeneva 1202tadashi.ito@graduateinstitute.chQuality competition versus price competition goods: Anempirical classificationRichard E. Baldwin and Tadashi Ito♦Graduate Institute of International and Development Studies, GenevaAbstract:Based on the recent trade models of the Heterogeneous Firms Trade (HFT) model and theQuality Heterogeneous Firms Trade (QHFT) model, we classify export goods (at the HS6-digit level of disaggregation) by quality and price competition. We find a highproportions of quality-competition goods for the major EU countries and lowerproportions for Canada, Australia and China. However, the overlap of thesequality-competition goods is not large, which suggests that characteristics of exportgoods are substantially different across countries at the same HS 6-digit code.Key words: Quality vs Price competition, heterogeneous firms trade model.JEL Classification: F141. I NTRODUCTIONRecent work on the theory and empirics of firm heterogeneity and trade provides new and wide ranging insights. In the mainstay model in this ‘new new trade theory’ – the heterogeneous firms trade model of Melitz (2003) – competitiveness of a firm’s product depends upon price; the cheapest goods are the most competitive. A minor twist on this model (which was foreshadowed by a footnote in Melitz 2003) turns the standard heterogeneous firms trade (HFT) model into the quality heterogeneous firms trade (QHFT) model where competitiveness depends upon the quality-adjusted price. If consumers care enough about quality, the highest priced goods are the most competitive, so the association between observed price and competitiveness is reversed, i.e. firms with the lowest observed prices are the least competitive.1A simple empirical prediction separates the HFT and QHFT models in trade data. Since trade costs rise with distance of the market, the HFT model predicts that products with the lowest price get sold in the most distant markets while the opposite holds in the QHFT, i.e. the highest priced goods travel the furthest. These diametrically opposed implications provide the foundation of a test of the models by Baldwin and Harrigan (2006), BH henceforth; that paper, however, pools across all categories of US exports thus implicitly assuming that all US exports are characterised either by a fallingprice-distant link (HFT) or by a rising price-distant link (QHFT).Our paper follows up on the BH by estimating the price-distance relationship separately for each product using panel data. Our paper’s main value-added is to establish a list of three types of products. Those where competition appears to be based on price, those where it is based on quality, and those that cannot be confidently placed in either category. Specifically we use export data for nine large exporting nations at the HS 6-digit2level of disaggregation. Our key findings are:*11 Avenue de la Paix, 1202 Geneva, Switzerland; Baldwin@graduateinstitute.ch,Tadashi.Ito@graduateinstitute.ch.1 See Baldwin and Harrigan (2006).2 In the text below, the terms ‘HS 6-digit’ and ‘HS6’ are used interchangeably.1) Of the HS 6-digit codes that can be clearly classified as quality or price competition, 50 to 60% of HS 6-digit codes exports of large European nations can be classified as ‘quality goods’, while only 30 to 40% of US and Japanese exports fall into this category.We believe that the difference may lie in pervasive trade in parts and components stemming from US and Japanese companies’ offshoring strategies that means nearby customers (the offshored factories) are a different type of buyers than the far away customers (arm’s length purchasers).2) For commodity exporters like Canada and Australia, the fraction of quality goods is much lower, only 15-25%. The share of quality goods in China’s exports also fall in this range.We believe that this fits in with our priories that nations with a comparative advantage in raw materials should systematically see a lower incidence of quality-type goods in their export mix. LiteratureOne of the pioneering articles on the empirical front to use price as a proxy for quality is Schott (2004). It has documented a large difference in product prices within the most disaggregated level of product classification. Schott (2008) shows that the US consumers pay less for “Made in China” than for “Made in OECD” for similar goods. Fontagné, Gaulier, and Zignago (2008), analysing unit prices of HS 6-digit products of 200 countries, finds that the developed countries’ products are not directly competing with the developing countries’ products. Especially, because of their products’ superior quality, EU countries have less direct competition with the developing countries than Japan or the US does. These findings have important policy relevance. It suggests that developed countries can maintain their competitiveness by climbing up the quality ladders within the existing industries rather than moving to a new industry. But which goods are quality goods? We, consumers, also know that some goods are not competing in qualities but in prices. Commodity goods and raw materials are mostly competing in prices. Thus, it is interesting and useful for policy purposes to sort out products by the degree of quality or price competition.Plan of paperSection 2 briefly reviews the theory that structures our empirical exercise. Section 3 explains the data, estimation equation and results. The final section concludes.2. T HEORETICAL FRAMEWORKTo structure our empirical analysis, we briefly summarize the price competition and quality competition versions of the heterogeneous firms trade model, highlighting two simple empirically testable predictions of these models.The classic HFT model (Melitz 2003) can be thought of as the Dixit-Stiglitz monopolistic competition trade model where firms have randomly drawn marginal cost functions and face iceberg trade costs as well as a fixed cost of establishing a ‘beachhead’ in each market. As usual, theDixit-Stiglitz structure links the value of sales directly to operating profits, so the beachhead cost means that only sufficiently competitive firms export. Moreover, distance-linked iceberg trade costs imply that a firm’s competitiveness is diminished in more distant markets, so export status displays a distance-marginal cost gradient. The threshold degree of competitiveness necessary to sell in markets rises with the market’s distance, so average competitiveness of firms servicing a particular market rises with distance.The HFT and QHFT models differ only in their determinants of competitiveness. In HFT, price is the sole basis of competition, i.e. market entry thresholds can be written in terms of a maximum price. In QHFT, competitiveness depends upon quality-adjusted price, so market-entry thresholds are defined in terms of quality-adjusted price. In the standard version of the model, the lower quality-adjusted prices (unobserved) are associated with higher unadjusted (observed) prices. In other words, firms only export the most expensive goods to the most distant markets.The BH test of this prediction found that the QHFT provided a better explanation of the US export data for 2005. That finding, however, pools across all US exports, thus implicitly assuming that all US exports are marked either by quality competition or by price competition.In this paper, we explore the hypothesis that some goods may fit HFT predictions while others fit the QHFT predictions. The hope is that we can identify a set of products which are – for a number of major exporting nations – characterised by either HFT or QHFT.3. D ATA , EMPIRICAL MODEL AND RESULTSTaking the distance-price prediction to the data requires some care in handling the theoreticalpredictions. Suppose we had the true product-level data, i.e. data on the prices and sales by particular firms of particular products in particular destination markets. If the baseline model is true,Dixit-Stiglitz mark-up pricing would imply that the producer price, i.e. FOB price, for each variety would be insensitive to distance. The point is that the distance-price-gradient prediction stems from product/firm selection, not from firms’ pricing behaviour.However, if we work with publicly available trade data, where the finest disaggregation available for all nations is HS 6-digit for all nations (HS 9-digit or HS 10-digit for some nations) then distance will have a selection effect. We should find that the average export price rises (QHFT) or falls (HFT) due to an unobserved shift in the bilateral composition of varieties/firms.For example HS6 category 854449 comprises “Other electric conductors for a voltage less than or equal to 80 volts”. Inside this category will be some high priced varieties and some low pricedvarieties (they coexist in both models due to product differentiation). The empirical lever comes from the way the nation-specific price mix changes with distance of the market. If QHFT is correct, Germany’s HS 854449 export basket to France will have more low priced varieties than its export basket to the US. Empirically, this will show up as a lower unit value index for Germany’s HS 854449 exports to France. If the HFT model is correct, we should observe the opposite.We conduct the analysis at the HS 6-digit level because this is the most disaggregated internationally harmonised classification code. Thus if our classification is to prove useful for a broad range of nations, it must be at the HS 6-digit level. Below, we report some sensitivity analysis at the HS 9-digit level for Japan.3.1. Empirical model and resultsThe empirical model we employ is akin to BH. The main differences lie in our use of log-linear distance (instead of distance bands) and our panel dimension.BH uses a panel for US exports of different products to different destinations but for a single year. Our panel data looks at a given origin nation’s exports of a given HS6 product to all the destination countries over a ten years period (1997-2006). For example, as is shown below, 4,845 HS 6-digit lines have at least 20 observations for the whole period. We run 4,845 regressions for the US. We do the same for the other 8 exporters. In total, we estimate approximately 40,000 regressions. The regression equation is:()()()d t d t d t d d t D GDPCAP GDP DIST p ,4,3,210,~log log log εβββββ+++++=where ,t d p is the log of the FOB unit value index to destination country d at time t, d DIST is the bilateral distance from the exporter under study and destination country d, and ,t d GDP is the destination-country GDP at time t ; ,t d GDPCAP is the corresponding GDP per capita. D is a vector of year dummies. d t ,ε is an iid error.3.2. DataThe export data we use is for 9 exporters (the world’s top 8 exporters plus Australia) for 1997 to 2006. These are taken from the UN COMTRADE database. The distance data are from CEPII; the GDP and population data are from the World Development Indicators of the World Bank.For the nine exporting nations we work with, Table 1 shows the world export rank and the number of HS 6-digit lines with at least 20 observations.Table 1: Global export rank and numbers exported HS6 linesUS Germany Japan China France UK Italy Canada Australia Rank 1 2 3 4 5 6 7 8 26 Lines 4,845 4,550 4,150 4,557 4,674 4,751 4,664 3,465 3,942 Source: UN COMTRADE, Author's calculation.3.3. ResultsTable 2 summarises the results.3The first column shows the number of HS6 products for which the distance coefficient is statistically significant at least at the 5% level. The second and third columns show the breakdown between the lines with positive and negative coefficients on distance, respectively. The first three lines show the results for the US, Germany and Japan. Consider the US numbers.Out of the US’s 4,845 HS 6-digit products, 1,957 products have statistically significant distance coefficients with 1,667 of these being positive. This suggests that about 34% of US HS6 exports are ‘quality goods’, about 6% are ‘price goods’. The remainder, almost 60%, cannot be classified, perhaps because the statistical groupings bundle together some price and some quality products. The results for Japan are broadly consistent with those for the US, with 38% of the HS6 lines displaying positive distance coefficients (suggesting quality competition) and 9% displaying negative coefficients.Findings for the four large EU exporters, Germany, France, Britain and Italy, reveal a much higher share of quality goods. About 50% of German, French and British exports are classified as quality goods, while the figure for Italy is almost 60%. We also note that the share of unclassifiable lines is much lower for these nations, with the share range from 33% for Italy to 48% for Britain, while France and Germany both close to 40%.An informal test is given by contrasting these results for highly industrial nations with nations who are known to be more dependent on commodity exports where we expect price to matter more than quality.Australia and Canada are the nations we chose as they are both large exporters, heavily reliant on primary good exports and have excellent data. For these two nations the share of quality goods is only 15% (Canada) and 27% (Australia). The share of price goods is 7% for Canada, and 5% for Australia. China presents an interesting case. Its exports are dominated by industrial goods, but it is widely perceived to be an export of varieties where low prices are the key to their success. What we find is that about 21% of its exports are quality-goods by our measure and 17% of its exports are price goods.3 See the separate file for the whole list of quality and price competition goods by country.Table 2: Numbers of quality-competition and price-competition goodsNumber HS6 lines where distance is significant at5% Number with positivecoefficient(quality competition)Number with negativecoefficient(price competition)USA 1,957 1,667 290 Germany 2,531 2,251 280Japan 1,947 1,590 357Overlap (J, D, US)510 322 1France 2,749 2,519 230UK 2,464 2,232 232Italy 3,136 2,994 142Canada 754 510 244 Australia 1,255 1,075 180China 1,722 946 776 Source: UN COMTRADE, Authors' calculation.3.4. Overall among US, German and Japanese quality goodsThe next question is whether these goods classified at HS 6-digit level are common to the countries in study. The fourth row of Table 2 shows the number of HS 6-digit lines that overlap among the US, Japan and Germany, i.e. the number of products which show statistically significant coefficient estimates of the same sign for the distance variable for all the three countries.Out of 3,905 HS 6-digit product lines which were common for all the three countries, 510 show statistically significant coefficients for all the three countries. Out of the 510 product lines, 322 show statistically significant positive coefficient estimates for all the three countries. We would like to suggest that these HS codes could be considered as marked by ‘quality goods’. The 322 figure represents just 8% of the 3,905 HS 6-digit product lines exported (about 10% in terms of export value).Only one HS 6-digit code has statistically significant negative coefficient estimate for all the three countries.There are 157 products that show two positive signs and one negative sign, so maybe we could call these quasi-quality competition goods. 30 products show one positive sign and two negative signs. The proportion of quality and quasi-quality competition goods is much higher than price andquasi-price competition goods. The rather small proportion of the overlap of product codes across the three countries implies that the product mixture in terms of quality/price competition for a particular HS 6-digit code is different across countries.3.5. More detailed disaggregationFact that less than one out of ten lines can be unanimously classified as quality or price goods suggests that there may be a great deal of heterogeneity (across exporters) among the basket of goods included in each HS6 category.To investigate the hypothesis, we compare the analyses at HS6 results with estimates on HS 9-digit data for Japan. Specifically we reproduce the above procedure for all the HS9 lines within given HS6 codes. Since the purpose here is a simple check, not an exhaustive analysis, we have conducted an analysis using a random sample from HS codes.Japan has approximately 5,000 lines at the HS6 level with roughly 9,100 lines at the HS9 level. Some HS6 codes have only a single HS9 code, rendering our test invalid so we discard all such HS6 codes and then take a 1 % random sample of the remaining HS6 codes. For these randomly sampled HS6 codes, we have taken the export data at the HS9 level. The regression is run for each HS 9-digit code. The test will come from comparing the distance coefficient estimates for the HS6 aggregate with the more disaggregate estimates for the HS9 codes encompassed by the HS6 code.Table 3 summarises the results. The left panel shows that HS6 result, with the first column displaying the HS6 code, the second the distance coefficient and the third the p-value. The fourth column summarise the finding by putting a + or – where the distance coefficient is positive or negative at the 5% level respectively. The right panel shows similar statistics for the HS9 codes that make up the HS6 code listed. The final column summarises the match between the two as a half-match (H), a full-match (F) or more-than-half-match (MF). N indicates no-match.If HS9 heterogeneity is a key source of the low number of goods that can be clearly classified as quality or price goods, then we should see a stark mismatch between the results indicated by the HS9 data and the more aggregated HS6 data, i.e. many “N” in the final column.Out of the total 16 HS 6-digit codes we checked, 7 have full fit and 3 have more than a half fit. Only 3 have no match. Closer examination of the no-match cases is revealing. In two of the cases (520544 and 611120), the distance coefficient is positive and significant for the data pooled at the HS6 level, but none of the underlying HS9 coefficients are significant. We note however that the HS9 coefficients are positive. This suggests that the lack of variation in the HS9 export destinations may account for the lack of statistical significance.The remaining case of no match (901890) is very instructive. Here we see that most of the HS9 coefficients are positive, but one is negative. The aggregate HS6 coefficient is estimated to be negative but not significantly different from zero. This case suggests that the HS6 classification is inappropriate for our purposes in that it pools price and quality goods. If this sort of result were widespread, then it would cast doubt on our HS6 results, but the fact that it occurs in only one of the 16 cases provides some assurance that our HS6 estimates are yielding useful results.While further testing is required, using for example US HS10 and EU HS8 data, our exploratory investigation suggests that analysis at HS6 level provides a reasonably good indication of the underlying situation. It is particularly important to note that in no case did the HS6 result indicate that the line was a quality or price good when the HS9 data indicated otherwise.Our finding does not resolve the issue of the low number of clearly classifiable HS6 codes. We cannot say whether there is something wrong with our empirical framing of the question, or whether the problem lies in heterogeneity (by exporting country) of basket of goods in the HS9 codes.Table 3: HS6 vs HS9 estimatesHS6 codeDistancecoefficient pSign of significantcoefficients HS9 codeDistancecoefficient pSign of the coefficientestimate Fit030791 0.79 0.00 + 0307911000.54 0.060307911000.81 0.00+H 370252 0.23 0.00 + 3702520000.20 0.00+3702521000.26 0.00+F 390290 -0.03 0.73 3902901000.11 0.133902909000.15 0.20F 500720 0.11 0.12 5007201100.28 0.055007201200.09 0.135007201900.15 0.075007202000.19 0.20F520544 0.21 0.01 + 5205441000.04 0.775205449000.15 0.13N 520831 -0.24 0.01 - 520831100-0.32 0.01-520831200-0.05 0.62520831300-0.15 0.05-520831900-0.21 0.04-MH540744 -0.17 0.10 540744100-0.18 0.30540744900-0.14 0.17F 610690 0.33 0.00 + 6106901000.51 0.00+6106909000.17 0.51H 610990 0.40 0.00 + 6109901100.67 0.00+6109901200.51 0.00+6109901900.34 0.00+6109909100.23 0.106109909900.46 0.02+MH611120 0.35 0.00 + 6111202950.02 0.896111203000.12 0.496111209000.01 0.95N611610 -0.25 0.00 - 611610000-0.36 0.02-611610500-0.14 0.14H 710692 0.94 0.00 + 7106921000.82 0.00+7106929000.43 0.00+F 841430 0.32 0.00 + 8414301000.29 0.00+8414309000.24 0.00+F 845630 0.20 0.00 + 8456301100.18 0.00+8456301900.23 0.00+8456309000.80 0.00+F854449 0.10 0.29 8544491000.17 0.628544491100.58 0.00+8544491900.70 0.00+8544499100.02 0.85854449990-0.05 0.71MH901890 -0.06 0.32 9018901100.12 0.00+9018901900.20 0.00+9018902000.59 0.00+9018903110.05 0.619018903190.33 0.00+901890390-0.31 0.00-9018909000.12 0.25N4. C ONCLUSIONThis seeks to classify HS6 digit products as being characterised either by price-competition or by quality-competition goods as suggested by the HFT and QHFT models. We find that about 8% of HS6 codes can be thus classified in the sense that results for the US, Germany and Japan all coincided.Of the goods that can be clearly classified, we find that the major EU countries are leading the quality competition race with 50 to 60 % of their exports being goods in which quality seems to matter in the sense that the goods that get sold to the most distant markets are the most expensive ones. For Japan and the US the figures are lower at 38 and 34 % respectively. Canada, Australia and China have much lower proportions of quality-competition goods.To check for problems with aggregation, we analyse Japan’s export data at the HS 9-digit level and its aggregation into the HS6 scheme. We find few difference in the inferences that come from analysis at the HS9 versus HS6 level.R EFERENCESBaldwin, Richard and Harridan, James (2007). "Zeros, Quality and Space: Trade Theory and Trade Evidence " CEPR Discussion Paper No. 6368.Baldwin, Richard (1988). "Hysteresis in Import Prices: The Beachhead Effect," American Economic Review, American Economic Association, vol. 78(4), pages 773-85, September.Fontagné, Gaulier, and Zignago. (2008) "Specialization across varieties and North-South competition", Economic Policy, January 2008, 53-91.Krugman, P. (1980) “Scale Economies, Product Differentiation and the Pattern of Trade” American Economic Review, 70, 950-959.Melitz, Marc J. (2003), .The Impact of Trade on Intra-Industry Reallocations and Aggregate Industry Productivity,. Econometrica, 71:6, pp. 1695-1725.Schott, Peter. (2008) "The relative sophistication of Chinese exports", Economic Policy, January 2008, 7-49.。
TW 142数学名词-中小学教科书名词中英对照术语
Novel type of phase transition in a system of self-driven particles
A simple model with a novel type of dynamics is introduced in order to investigate the emergence of self-ordered motion in systems of particles with biologically motivated interaction. In our model particles are driven with a constant absolute velocity and at each time step assume the average direction of motion of the particles in their neighborhood with some random perturbation (η) added. We present numerical evidence that this model results in a kinetic phase transition from no tran |va| = 0) to finite net transport through spontaneous symmetry breaking of the rotational symmetry. The transition is continuous since |va| is found to scale as (ηc − η)β with β ≃ 0.45.
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One of the most interesting aspects of many particle systems is that they exhibit a complex cooperative behavior during phase transition [1]. This remarkable feature of equilibrium systems has been studied in great detail for the last couple of decades leading to a deeper understanding of processes which may take place in an assembly
2024年美赛c题思路
2024年美赛c题思路全文共四篇示例，供读者参考第一篇示例：【2024年美赛C题思路】2024年美国大学生数学建模竞赛（MCM/ICM）是一场备受全球瞩目的学术赛事，吸引了来自世界各地的数学爱好者和专业人士参与。
C题始终是竞赛中最具挑战性和创新性的题目之一，要求参赛选手在72小时内运用数学建模的方法解决一个现实世界的问题。
2024年的C 题究竟是什么呢？本文将对这个问题进行探讨，并提出一些可能的思路。
我们可以假设2024年的C题围绕着某一种新兴科技或者社会现象展开。
近年来人工智能和大数据技术的发展迅猛，可能会对人类社会产生巨大的影响。
可能的C题之一就是要求参赛选手利用数学建模的方法，分析人工智能和大数据技术对社会经济、文化、政治等方面的影响，并提出相应的应对措施。
环境问题也是当今世界面临的重大挑战之一。
2024年的C题可能会围绕着气候变化、环境保护、资源利用等方面展开。
参赛选手可以通过建立相关的数学模型，分析气候变化对生态系统和社会经济的影响，并提出相应的应对策略。
2024年的C题还可能涉及到医疗卫生领域。
随着医疗技术的不断发展和普及，人们对于健康和医疗服务的需求也在不断增加。
可能的C 题之一就是要求参赛选手利用数学建模的方法，分析医疗资源的分配问题、疾病传播模式以及医疗服务的效率等方面的问题，并提出相应的改进措施。
2024年的美赛C题可能涉及到科技、环境、医疗等多个领域，要求参赛选手综合运用数学建模、数据分析、计算机仿真等方法，提出创新性的解决方案。
参赛选手在解答C题的过程中，需要具备良好的数学建模能力、创新思维能力和团队合作能力，从而在竞赛中取得优异的成绩。
希望未来的参赛选手能够充分准备，充满信心地迎接2024年美赛C题的挑战。
第二篇示例：2024年美赛c题是一道具有挑战性的数学建模题目，需要参赛队伍充分发挥自己的数学建模能力和创造力，找到最优的解决方案。
本文将围绕2024年美赛c题展开思路讨论，希望对参赛队伍提供一些启发和帮助。
EMC CLARiiON AX4 存储系统
高级功能首先要具有既能满足当今需要又可满足未来要求的可扩展性。单控制器 AX4 机型是一种部署外部存储系统的低成本方法，它可为应用程序（如磁盘备份）和各种 数据归档任务提供一个经济的存储平台。双控制器机型提供了业务关键数据和应用程 序所需的优异的可用性、连接性和性能。
12 个磁盘驱动器无法满足您所需要的容量和性能？ AX4 可以通过四个扩展机箱扩展到 60 个驱动器，容量高达 60 TB，因此所提供的预留空间能够让用户和应用程序使用起来 绰绰有余。AX4 的功能不仅仅局限于提供巨大的存储容量。它还能够为多达 64 个主机 提供整合存储，因此 AX4 为那些因日益发展壮大而需要添加服务器和应用程序的公司 提供了最大的灵活性。
对于光纤通道 AX4 系统而言，附加的 EMC MirrorView™ 软件支持在阵列之间进行同步或 异步数据复制，从而最大限度地提高了数据可用性并实现了全面的灾难恢复解决方案。 EMC SAN Copy™ 软件支持在 AX 和 CX 系列机型之间、进行数据迁移的多供应商阵列之间， 以及边缘到核心环境（如远程或卫星办公室）之间进行高速数据复制。
可选的高级管理和数据复制功能
可选的 Navisphere Manager Suite 能够扩展 AX4 的功能，从而满足日益发展壮大而且地理 分散的公司的需要。Navisphere Manager 可通过单个控制台来管理多个 CLARiiON 阵列， 包括 AX 和 CX 系统。同时它还支持自身所包含的 EMC SnapView™ 软件，以实现多个时间 点快照功能以及对关键数据的完整卷拷贝。
出色的连接性
AX4 可提供 iSCSI 和光纤通道两种机型，使公司能够选择适用于其环境的网络互连设备。 AX4 iSCSI 阵列将普遍可用的 IP 网络组件用于直连网络或使用传统以太网交换机的网络， 从而为实现经济高效的共享存储系统奠定了基础。具有 4 Gb/s 光纤通道连接的 AX4 阵 列利用成本较低的主机总线适配器，提供了经济高效的直连配置以及广泛的 SAN 交换 机选项，最多可为 64 个高可用性服务器创建 SAN。每个控制器均支持两个前端端口， 即 4Gb/s 的光纤通道或 1 Gb/s 的 iSCSI。
2024年美赛a题解题思路
2024年美赛a题解题思路
2024年美赛A题的解题思路可能会涉及到不同的问题和领域，因此我会尽量从多个角度来回答你的问题。
首先，如果A题是一个数学建模题，可能需要分析问题背景，建立数学模型，进行求解和分析。
解题思路可以包括对问题进行分析，确定问题的关键因素和约束条件，建立数学模型，选择合适的数学工具和方法进行求解，最后对结果进行解释和验证。
其次，如果A题是一个工程或科学问题，解题思路可能涉及到实验设计、数据采集与分析、模拟仿真等方面。
解题思路可以包括对问题进行实地调研和数据收集，建立合适的模型或者实验方案，进行数据处理和分析，最后得出结论并进行结果的验证和讨论。
另外，A题可能也涉及到计算机科学和信息技术方面的问题，解题思路可能包括算法设计、程序编写、系统设计等方面。
解题思路可以包括对问题进行需求分析，设计合适的算法或者系统架构，编写程序实现，进行测试和优化，最后得出结果并进行讨论。
总的来说，解题思路可能涉及到数学建模、工程科学、计算机
科学等多个领域，需要根据具体的题目要求和问题特点来确定合适的解题思路。
希望这些信息能够对你有所帮助。
如何用赛灵思FPGA实现4G无线球形检测器
如何用赛灵思FPGA实现4G无线球形检测器 MIMO无线系统最佳硬判决检测方式是最大似然(ML)检测器。
ML检测由于比特误码率 (BER)性能出众，十分受欢迎。
不过，挺直实施的复杂性会随着天线和调制计划的增强呈指数级增加，使ASIC或仅能用于用法少数天线的低密度调制计划。
WiMAX对宽带互联网接入犹如手机对语音通信一样意义非凡。
它可以取代DSL和有线服务，随时随地提供互联网接入。
只需要打开计算机，衔接到最近的WiMAX天线，就可以畅游全世界的网络了。
宽带互联网接入碰到的最大挑战之一就是移动性，而这正是最新的WiMAX标准所要解决的。
IEEE 802.16e-2005介绍了传输和接收过程中多根天线的使用，即MIMO概念，又称为多输入多输出，是移动WiMAX 的一个关键特性。
空分复用(SDM) MIMO处理可显著提高频谱效率，进而大幅增强无线通信系统的容量。
空分复用MIMO通信系统作为一种能够大幅提升无线系统容量和衔接牢靠性的手段，近来吸引了人们的广泛关注。
MIMO无线系统最佳硬判决检测方式是最大似然(ML)检测器。
ML检测由于比特误码率 (BER)性能出众，十分受欢迎。
不过，挺直实施的复杂性会随着天线和调制计划的增强呈指数级增加，使ASIC或FPGA仅能用于用法少数天线的低密度调制计划。
在 MIMO检测中，既能保持与最佳ML检测相媲美的BER性能，又能大幅降低计算复杂性的精彩办法非球形检测法莫属。
这种办法不仅能够降低SDM和空分多接入系统的检测复杂性，同时又能保持与最佳ML检测相媲美的BER性能。
实现球形检测器有多种办法，每种办法又有多种不同算法，因此设计人员可以在诸如无线信道的吞吐量、BER以及实施复杂性等多项性能指标之间寻求最佳平衡。
虽然算法(比如K-best或者深度优先搜寻)和硬件架构对MIMO 检测器的终于BER性能自不待言有极大的影响，不过普通在球形检测之前举行的信道矩阵预处理也会对MIMO检测器的终于BER性能产生巨大影响。
Catmull-Clark细分曲面正则性研究的开题报告
Catmull-Clark细分曲面正则性研究的开题报告一、选题背景和意义在三维计算机图形领域，曲面的建模和呈现是一个重要的研究方向。
而细分曲面技术则是实现高质量、高精度曲面建模的关键性技术之一。
Catmull-Clark细分曲面作为一种经典的细分方法，在计算机图形学和计算机动画领域得到了广泛的应用。
然而，由于其在实际应用中存在的某些问题，如高次粗糙性和不规则边界等问题，使得其仅适合用于静态模型的构建，而不适用于实时动态模型的交互式细分。
因此，对Catmull-Clark细分曲面正则性研究的深入探究，对于解决其存在的问题具有非常重要的指导意义，能够推动细分曲面技术的发展和应用。
二、研究内容和方法1.研究内容：本次论文研究将围绕Catmull-Clark细分曲面的正则性问题展开，具体包括：（1）Catmull-Clark细分曲面的数学模型及其细分过程介绍；（2）Catmull-Clark细分曲面出现的高次粗糙性问题及其解决方法；（3）Catmull-Clark细分曲面出现的不规则边界问题及其解决方法；（4）Catmull-Clark细分曲面的应用案例展示。
2.研究方法：（1）文献调研：通过查阅相关文献、书籍及论文，对Catmull-Clark 细分曲面的基本模型及其正则性问题进行了解和分析。
（2）理论分析：通过对Catmull-Clark细分曲面的数学公式进行解析推演，分析其出现的问题及其原因。
（3）实验验证：通过编程实现Catmull-Clark细分曲面的细分算法，并进行不同参数的实验验证，以验证本文提出的问题解决方法的有效性。
三、预期成果和意义本课题的预期成果为：（1）掌握Catmull-Clark细分曲面的基础知识，了解其细分过程和数学模型；（2）深入分析Catmull-Clark细分曲面出现的高次粗糙性问题和不规则边界问题，并提出一些相应的解决方法；（3）通过实验验证，验证所提出的解决方法的有效性和可行性；（4）展示Catmull-Clark细分曲面在实际应用中的成果和应用案例，推广其应用。
限制对比度 截取参数
限制对比度截取参数
限制对比度自适应直方图均衡化（Contrast Limited AHE，CLAHE）是一种改进的自适应直方图均衡化方法，用于提高图像的对比度并减少噪声放大。
在CLAHE中，限制对比度是通过剪裁直方图并重新分配像素值来实现的。
以下是CLAHE方法中涉及到的主要截取参数：
1. 裁剪限制：这是直方图中被剪裁的值，用于限制对比度放大。
它取决于直方图的归一化，从而间接取决于邻域区域的大小。
常见的做法是将放大限制在3到4之间。
2. 邻域累积分布函数（CDF）斜率：CLAHE方法中，给定像素值附近的对比度放大由变换函数的斜率给出。
这与CDF的斜率成正比，因此与像素值处的直方图值成正比。
通过限制CDF的斜率，可以进一步限制转换函数的斜率。
3. 直方图裁剪与重新分配：在CLAHE中，直方图被剪裁的值取决于图像。
为了避免过度放大，可以在所有直方图直条之间平均重新分配被剪裁的部分。
重新分配过程可以递归地进行，直到超出的部分可以忽略不计。
综上所述，CLAHE方法通过限制对比度来改善图像质量，适用于处理低对比度图像和含有噪声的图像。
在实际应用中，可以根据具体需求和图像特点调整这些截取参数，以获得更好的图像增强效果。
1解释clahe的原理过程 -回复
1解释clahe的原理过程-回复标题：详解CLAHE（对比度受限自适应直方图均衡化）的原理过程CLAHE，全称为Contrast Limited Adaptive Histogram Equalization （对比度受限自适应直方图均衡化），是一种广泛应用于图像增强和预处理的技术。
其主要目标是提高图像的局部对比度，特别是在图像的暗区和亮区，以改善图像的整体视觉效果和后续处理的准确性。
一、直方图均衡化原理在深入理解CLAHE之前，我们首先需要理解直方图均衡化的基本原理。
直方图均衡化是一种将图像的灰度分布调整为均匀分布的过程。
它通过计算图像中每个像素值的出现频率（即直方图），然后重新分配像素值，使得所有像素值的出现概率相等。
这样，原本集中在某一灰度范围的像素就会被分散到更广泛的灰度范围内，从而提高了图像的整体对比度。
二、自适应直方图均衡化（AHE）然而，直方图均衡化是一种全局操作，对于包含多个亮度区域的复杂图像，可能会导致过度平滑或者噪声增强的问题。
为了解决这个问题，引入了自适应直方图均衡化（AHE）。
AHE的基本思想是将图像分割成小的子块（也称为tiles），然后对每个子块进行独立的直方图均衡化。
这样，每个子块的对比度都能得到提升，同时保持了图像的局部特性。
三、对比度受限自适应直方图均衡化（CLAHE）虽然AHE在一定程度上解决了全局直方图均衡化的局限性，但仍然存在一个问题：当某个子块内的像素值过于集中时，经过直方图均衡化后，可能会产生“溢出”现象，即生成的像素值超出了原始像素值的范围。
为了解决这个问题，CLAHE引入了对比度限制的概念。
具体来说，CLAHE在进行直方图均衡化之前，会对每个子块的直方图进行Clip（裁剪）操作，将超过特定阈值的像素值归一化到该阈值。
这样，就可以避免因像素值过大而导致的“溢出”问题。
以下为CLAHE的具体步骤：1. 图像分割：将原始图像分割成小的子块。
2. 直方图计算：对每个子块计算其灰度直方图。
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CLARiiON AX4 Differentiators
High availability and reliability—Based on proven CLARiiON technology that delivers the highest levels of availability and reliability in midrange storage systems
Single Controller 3 TB raw capacity 4 750 GB SATA drives 3-years next business day onsite service
Dual Controllers 3.6 TB raw capacity 12 300 GB SAS drives 3 years next-business day onsite service
Dual Controllers 15.6 TB raw capacity 12 300 GB SAS, 12 750 GB SATA Comprehensive management Advanced local and remote replication Premium 4-hour response service
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Introducing the CLARiiON AX4
The CLARiiON AX4 is a simple, scalable, and reliable storage system equipped with a full suite of software at an extremely competitive price An easy, affordable superior alternative to server-based storage Cost-effective consolidation and automation Advanced technology for superior performance and value:
Easy to install and maintain
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3
CLARiiON AX4 Storage System
Scales from 4 to 60 drives
– Up to 60 TB*
Available with single or dual controller Fibre Channel or iSCSI connectivity Disk drive options
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Competitive System Pricing Comparison (U.S. List Price)
Entry-Level
$32,000 $28,000 $24,000 $20,000 $16,000 $12,000 $8,000 $4,000 $0 $8,599 $9,000 $14,100
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Table of Contents
CLARiiON AX4 overview CLARiiON AX4 differentiators Hardware comparisons Software comparisons Support and serviceability Supporting materials
Most capable and affordable entry-level SAN for VMware—Enable and support new VMware functionality, such as VMotion, Site Recovery Manager, and High Availability
Scales up to 60 drives, and supports up to 64 highly-available hosts Offers advanced software capabilities for multi-array management and disaster recovery
– High-performance serial-attached SCSI (SAS) drives and high-capacity serial ATA (SATA) drives – 1 Gb/s iSCSI or 4 Gb/s Fibre Channel network connectivity for storage versatility
– Cache destage to disk – End-to-end data integrity checking
Ease of use—Simplicity that allows the IT generalist to act like a storage specialist
– Simple wizard-based installation process – Intuitive, Web-based management from anywhere on the network – Nondisruptive data movement between drive types and RAID Groups
Sample Use Cases: Operational and disaster recovery
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CLARiiON AX4 Entry-Level Competitors
Entry-level competing arrays
– – – – HP MSA1500, MSA1510i IBM DS3300, DS3400 Network Appliance FAS2020 Sun StorageTek 2530, 2540
CLARiiON AX4 competitive advantages over these arrays include:
– Support for a mix of SAS and SATA drives within the same drive shelf and virtual LUNs for nondisruptive data migration within the array – Lower price-point for midsize configurations, both with and without advanced software capabilities – Application integration and support via EMC Replication Manager for:
EMC CLARiiON AX4
IBM DS3400/ DS3300
HP MSA1500/ MSA1510i
EMC CLARiiON AX4
IBM DS3400/ DS3300
HP MSA1500/ MSA1510i
$0
EMC EqualLogic Network CLARiiON PS100E Appliance AX4 and FAS2020 PS3600X
Comprehensive interoperability support
– EMC E-Lab qualification and support for the most popular operating environments, including Windows, Linux, AIX, HP-UX, Solaris, Netware, and VMware – Cooperative Support Agreements with all server vendors
Scalability—Capacity, connectivity, and software functionality to support current and future needs
– More capacity and more than three-times the host connectivity – Optional, add-on software for local backup and recovery, and remote disaster recovery
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CLARiiON AX4 Scalable Competitors
Scalable competing arrays
– EqualLogic PS Series – Network Appliance FAS2020
– Support for a mix of SAS and SATA drives within the same drive shelf and virtual LUNs for nondisruptive data migration within the array – Optimal growth path
EMC CLARiiON AX4 Competitive Overview
EMC’s Competitive Advantage
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