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1.
An essential step for the realization of free-form surface structures is to create an efficient structural gird that satisfies not only the architectural aesthetics, but also the structural performance. Employing the main stress trajectories as the representation of force flows on a free-form surface, an automatic grid generation approach is proposed for the architectural design. The algorithm automatically plots the main stress trajectories on a 3D free-form surface, and adopts a modified advancing front meshing technique to generate the structural grid. Based on the proposed algorithm, an automatic grid generator named "St-Surmesh" is developed for the practical architectural design of free-form surface structure. The surface geometry of one of the Sun Valleys in Expo Axis for the Expo Shanghai 2010 is selected as a numerical example for validating the proposed approach. Comparative studies are performed to demonstrate how different structural grids affect the design of a free-form surface structure.  相似文献   

2.
The pitch-angle distribution of energetic particles is important for space physics studies on magnetic storm and particle acceleration.A‘pin-hole’imaging structure is built with the‘pin-hole’technique and a position sensitive detector,which can be used to measure the pitch angle distribution of energetic particles.To calibrate the angular response of the‘pin-hole’imaging structure,special experiment facilities are needed,such as the particle accelerator with special design.The features of this kind of particle accelerator are:1)The energy range of the outgoing particles should be mid-energy particles(tens keV to several hundred keV);2)the particle flux should be consistent in time-scale;3)the directions of the outgoing particles should be the same and 4)the particle number within the spot should be low enough.In this paper,a method to calibrate the angular response of the‘pin-hole’imaging structure by the90Sr/90Y β source with a collimator is introduced and simulated by Geant4 software.The result of the calibration with the collimated β source is in accord with the Geant4 simulations,which verifies the validity of this method.  相似文献   

3.
The restriction width of carcass by the belts( RWCB) as an important parameter of radial tire design has been neglected for a long time. In order to improve the accuracy and efficiency of tire profile design,the calculating method of RWCB is proposed. The equilibrium profile is calculated by geometric model and variational approach,based on it,the predicted model of RWCB is developed for tire design. Finally,four different designs of 12R22.5 tires are investigated by experiment and finite element method,which is used to validate the accuracy of the theoretical method. Results indicate that experimental and finite element analysis results are found to be in good agreement with theoretical results; linear relationships are existed between the cord length and RWCB,and also existed between the position of belt and RWCB; tires designed by the methods have smaller and more uniform displacement,so the method can be used for tire optimized design.  相似文献   

4.
In accordance with the confusion on classification of source rocks, the authors raised a source rock classification for its enriched and dispersed organic matter types based on both Aipern‘s idea^[1] and maceral genesis/composition. The determined rock type is roughly similar to paiynofacies of Combaz^[2], whereas it is “rockmaceral facies (for coal viz. coal facies)“ in strictly speaking. Therefore, it is necessary to use the organic ingredients classification proposed by the authors so that it can be used for both maceral analysis and environment research^[3]. This source rock classification not only shows sedimentology and diagenetic changes but also acquires organic matter type even if hydrocarbon potential derived from maceral‘s geochemical parameters. So, it is considered as genetic classification. The “rock-maceral facies“ may be transformed to sedimentary organic facies^[3], which is used as quantitative evaluation means if research being perfect. Now, there are many models in terms of structure either for coal or for kerogen. In our opinion, .whatever coal or kerogen ought be polymer,then we follow Combaz‘s thought^[2] and study structure of amorphous kerogens which are accordance with genetic mechanism showing biochemical and geochemical process perfectly, Here. we use the time-of-flight secondary ion mass spectrometry (TOFSIMS) to expand Combaz‘s models from three to five, They are also models for coal.  相似文献   

5.
A New Approach to Urban Rainwater Management   总被引:1,自引:0,他引:1  
Based on an analysis of our research results and the main problems relating to urban rainwater treatment, we propose a new approach to urban rainwater management in China. The necessity and feasibility of such a new approach are discussed. From an ecological point of view all components of the global system, including residents living in cities, have the same right to enjoy rainwater. Therefore, urban rainwater should neither be simply drained as waste water, nor be completely harvested as a kind of resource. The objective of this new approach is to maintain the natural hydrological cycle in urban areas during urbanization. When necessary, it could also be used to regulate the amount of runoff, evaporation and infiltration in a city in order to rehabilitate the hydrological cycle given the local conditions. Three basic principles should be adopted in rainwater management, i.e., separation of rainfall from sewage, limited utilization and small and decentralized facilities. Four methods can be used for urban rainwater management: rainwater harvest, rainwater infiltration, rainwater storage and rainwater pipes. The natural hydrological cycle in urban areas could be rehabilitated through rainwater management, which is of great importance for sustainable development of our cities.  相似文献   

6.
As per most other earth science engineering problems, the underground coal geotechnical environment and the way in which roof and rib support interacts with the rock mass are complex issues. It is therefore generally recognised that without prudent simplification, the complexity of the problem will overwhelm all current geotechnical methods of modelling, not least for the reason that a rock mass can never be characterised to a level that allows a ‘‘non-simplified" analysis. The fact that numerical models, which are commonly purported to be a ‘‘simulation" tool and the so-called epitome of advanced geotechnical engineering, always need to be ‘‘calibrated" to a known reality is taken to be conclusive proof of this statement. While the problem should not be oversimplified(i.e. the dominant failure mechanisms or critical data input parameters should not be ignored), without question judicious simplification is at the heart of all engineering design, to the point that it has a well-established name –‘‘reductionism". The hypothesis addressed in this paper, is that horizontal and vertical stress-driven slender beam and column behaviour(which includes unstable Euler Buckling) are respectively the dominant(but not only) roadway roof and ribline behavioural mechanism that(if not controlled) can lead to excessive deformation,failure and eventual collapse. As a part of the Scientific Method, a hypothesis can only be tested via real-world observations, measurements and analyses in establishing it is a credible Theory. Utilising the Scientific Method, this paper demonstrates that slender beam/column behaviour is the dominant instability mechanism within a coal mine roof/rib subject to elevated horizontal/vertical stress conditions and therefore, must be representatively accounted for in any credible empirical, analytical, or numerical approach to coal mine roof/rib stability assessment and associated ground support design.  相似文献   

7.
A novel approach,which can be used for dynamic characteristics analysis of machine tools based on unit structure(US),is reported in this paper.The concepts of unit structures for design of machine tools are defined.In order to satisfy the dynamic characteristics requirement of high natural frequency and light-weight of US,a design method of multi-disciplinary optimization of NSGA-II about unit structures driven by natural frequency and mass is developed.Through analyzing the unit structures,key factors affecting the natural frequency and mass are extracted,and the mathematical models of natural frequency and mass about unit structures are also established by using central composite design and response surface model.The goal of high natural frequency and light-weight is reached by using the multi-objective genetic algorithms.The Pareto optimal set is also obtained.The dynamic behavior of US is investigated by the experimental modal analysis.To show the efficiency of the proposed novel method,the example of YKW51250 gear shaping machine bed is used.Through optimization of NSGA-II about US of YKW51250 machine bed,the natural frequency of YKW51250 gear shaping machine bed is increased by 30.4%and its mass decreased by 5.2%comparing with the original design.By studying the dynamic characteristics of the simplified machine tools bed,useful laws are obtained,and these laws can be used in primary design of NC machine tools structures.The optimal method based on US can be also applied to the dynamic optimal design of machine tools and other similar equipments.  相似文献   

8.
The relationship between the hardware requirement of digital down converters(DDCs)in ultra-low symbol rate receivers and the word length is studied.Through analyzing the impact of word length selection to the system performance,a modified scheme is presented to decline the resource consumption without too much degradation on the signal to noise ratio(SNR).Theoretical analysis and numerical results demonstrate that compared to the traditional design,the proposed scheme could save dozens of memory resources.The scheme also includes some selectable parameters to achieve desired performance in various circumstances.Different from previous work in DDCs that concentrates mostly on the structure design,this paper considers special applications such as ultra-low symbol rate receivers.  相似文献   

9.
The Parameters Selection of SMA Optically Activated and Its Application   总被引:2,自引:0,他引:2  
Shape Memory Alloy (SMA) optically activated is the key lechnology of optical SMA activator,According to the shape memory mechanism of SMA ,researches are done on the activating response time and light wavelength of activating source elc of SMA optically activated to approach the parameters welection of optical activation ,SMA has the optimum efficiecy in the rage of 13 seconds to 27 seconds when SMA is illuminated continusly by wavelength of 675 nm;The power of light wave has a low effect on SMA ;the longer the activating wavelenth ,the quicker the response time of SMA activated ,If the proper activating time and activating wavelength,are adopted,and the structure deformation of composite material of SMA imbedded may be actiely controlled,and ideal effect will be gotten ,The resarch provides an evdence for the design of optical SMA activator and is of great significnce to its application ,Theresarch on smart structure has a wide application prospect.  相似文献   

10.
An induction motor with its speed modulated by frequency features wide transfer speed range, high systematic efficiency, simple structure and long life, and it therefore becomes one of the best driving motorsused in electrical vehicles. The present research trend of it is high power, high speed, high efficiency and longlife. How to meet the above requirements by using the electromagnetic design, structure design and heat de-sign, becomes a matter that needs to be resolved now. In this paper, the characters of the motor in operation areanalyzed, all kinds of factors that relate to life are laid out, its heating and loss are discussed and analyzed.The key reasons affecting the motor life are presented, and different characters of a high induction motor are compared with these of a general induction motor. A design idea is described, that is : we should consider how to improve the efficiency and reliability as well as how to reduce the heating by changing the electromagnet,structure, dissipation and operation of the motor. How to reduce its losses and to improve its dissipation has been presented in the paper.  相似文献   

11.
针对嵌入式系统的低功耗要求,采用位线分割结构和存储阵列分块译码结构,完成了64kb低功耗SRAM模块的设计.与一般布局的存储器相比,采用这两种技术使存储器的功耗降低了43%,而面积仅增加了18%.  相似文献   

12.
为了提高存储器的边界扫描测试软件的通用性,提出一种基于TCL语言及边界扫描技术的存储器测试脚本设计方案。结合存储器测试理论及边界扫描逻辑簇测试技术,研究基于TCL脚本语言的存储器测试脚本设计方法,用以在进行存储器簇测试时描述存储器自身的读写特性及与其外部边界扫描测试单元的连接关系等,并给出HY6264SRAM静态存储器功能测试的例子。通过测试验证,使用TCL脚本语言与高级语言联合编程能够提高边界扫描测试软件的工作效率。  相似文献   

13.
提出一种用于多机系统节.点机间通讯的新结构──广播式共享存储器.每个节点机都有一个双口SRAM,A口供本节点机“只读”,B口均连到公共“广播写”总线,供争到总线使用权的节点机广播写数,实现数据通讯.这种多机系统既具有共享存储器便于并行编程的优点,又能显著降低访问共享存储器发生冲突的概率,具有很好的性能价格比。本文所提出的通讯方案已用于由8个i860微处理器组成的多机系统中(峰值速度达640MFLOPS)实验的结果表明,这种方案可使节点机间的通讯速率得到大幅度提高。  相似文献   

14.
This paper combines improved Hamming codes and parity codes to assure the reliability of memory in presence of multiple bit upsets with low cost overhead.The redundancy bits of improved Hamming codes will be appended at the end of data bits,which eliminates the overhead of interspersing the redundancy bits at the encoder and decoder.The reliability of memory is further enhanced by the layout architecture of redundancy bits and data bits.The proposed scheme has been implemented in Verilog and synthesized using the Synopsys tools.The results reveal that the proposed method has about 19% less area penalties and 13% less power consumption comparing with the current two-dimensional error codes,and its latency of encoder and decoder is 63% less than that of Hamming codes.  相似文献   

15.
李龙镇  LEE  JH  KIM  TH  JIN  KH  PARK  MH  HA  PB  KIM  YH 《中南工业大学学报(英文版)》2009,16(3):467-473
A multi-bit antifuse-type one-time programmable (OTP) memory is designed, which has a smaller area and a shorter programming time compared with the conventional single-bit antifuse-type OTP memory. While the conventional antifuse-type OTP memory can store a bit per cell, a proposed OTP memory can store two consecutive bits per cell through a data compression technique. The 1 kbit OTP memory designed with Magnachip 0.18 μm CMOS (complementary metal-oxide semiconductor) process is 34% smaller than the conventional single-bit antifuse-type OTP memory since the sizes of cell array and row decoder are reduced. And the programming time of the proposed OTP memory is nearly 50% smaller than that of the conventional counterpart since two consecutive bytes can be compressed and programmed into eight OTP cells at once. The layout area is 214 μm × 327 μm, and the read current is simulated to be 30.4 μA. Foundation item: Project supported by the 2nd Stage of Brain Korea; Project supported by the Korea Research Foundation  相似文献   

16.
由于FPGA内部存储资源有限,通常需要使用外部扩展存储器,针对目前广泛应用的DDR2 SDRAM存储器,采用模块化方法设计了多端口存储控制器,详细介绍了控制器、仲裁器、译码器等关键模块的设计,并在开发板上进行了实现和测试,实验结果表明其有效带宽可达2.6 GB/s。  相似文献   

17.
针对内存管理中虚拟页面和物理页面连续分配的特性,提出可对相邻页面进行动态合并的旁路转换缓冲器(TLB)设计方法.该方法的核心思想是在处理器运行过程中,通过对相邻页面的递归合并,动态扩展单个TLB表项的地址映射范围,提高TLB表项的利用率并降低TLB缺失率.在两级TLB架构中,提出基于快速uTLB(fuT-LB)和影子uTLB(suTLB)动态切换的新型uTLB结构,作为两级TLB架构的一级缓存,为页面动态合并提供现场和载体,页面合并过程对软件透明.基于Mibench测试基准的实验结果表明,与filter-TLB架构相比,该页面动态合并方法可以平均降低TLB缺失率达27%.  相似文献   

18.
为解决DVB—s2标准下码长较长,译码器资源消耗较高,但速率要求较高的问题,研究了DVB-S2标准LDPC(LowDensityParityCheckCode)码译码器的硬件结构。利用校验矩阵周期特性,以16200bit码长和0.6码率为例,设计了基于共享内存和后验概率累加储存的译码器结构。实验表明,该设计的LDPC码译码器共消耗24004个逻辑单元,6437个寄存器和448594bit的RAM,吞吐率达到289Mbit/s,不仅吞吐量大,而且寄存器和内存资源的消耗也小。  相似文献   

19.
The compact full custom layout design of a 16 kbit mask-programmable complementary metal oxide semiconductor (CMOS) read only memory (ROM) with low power dissipation is introduced. By optimizing storage cell size and peripheral circuit structure, the ROM  相似文献   

20.
In this paper, the characterization of single event multiple cell upsets(MCUs) in a custom SRAM is performed in a 65 nm triple-well CMOS technology, and O(linear energy transfer(LET) = 3.1 Me V cm2/mg), Ti(LET = 22.2 Me V cm2/mg) and Ge(LET = 37.4 Me V cm2/mg) particles are employed. The experimental results show that the percentage of MCU events in total upset events is 71.11%, 83.47% and 85.53% at O, Ti and Ge exposures. Moreover, due to the vertical well isolation layout, 100%(O), 100%(Ti) and 98.11%(Ge) MCU cluster just present at one or two adjacent columns, but there are still 4 cell upsets in one MCU cluster appearing on the same word wire. The characterization indicates that MCUs have become the main source of soft errors in SRAM, and even though combining the storage array interleaving distance(ID) scheme with the error detection and correction(EDAC) technique, the MCUs cannot be completely eliminated, new radiation hardened by design techniques still need to be further studied.  相似文献   

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