一种高性价比的PVFS并行文件系统

分析PVFS并行文件系统的构成,得出客户机软件、元数据服务器软件和数据服务器软件之间的接口关系,然后研究一种由PC客户机、PC元数据服务器和低价数据服务器共同构成的PVFS系统,其中客户及与元数据服务器不做重要改变,数据服务器软件需要开发修改以适应新的硬件平台,使得以更低的成本实现相同的系统或者以相同的硬件成本实现更高的性能。     

A cross-junction channel valveless-micropump with PZT actuation

A gas-jet micro pump with novel cross-junction channel has been designed and fabricated using a Si micromachining process. The valveless micro pump is composed of a piezoelectric lead zirconate titanate (PZT) diaphragm actuator and fluidic network. The design of the valveless pump focuses on a cross-junction formed by the neck of the pump chamber and one outlet and two opposite inlet channels. The structure of cross-junction allows differences in fluidic resistance and fluidic momentum inside the channels during each PZT diaphragm vibration cycle, which leads to the gas flow being rectified without valves. The flow channels were easily fabricated by using silicon etching process. To investigate the effects of the structure of the cross-junction on the gas flow rate, two types of pump with different cross-junction were studied. The design and simulation were done using ANSYS-Fluent software. The simulations and experimental data revealed that the step-nozzle structure is much more advantageous than the planar structure. A flow rate of 5.2 ml/min was obtained for the pump with step structure when the pump was driven at its resonant frequency of 7.9 kHz by a sinusoidal voltage of 50 V_p–p.     

高成本和低成本MEMS加速度计性能比较研究

受微加工技术的限制,微机电系统(MEMS)加速度计在精度和可靠性方面存在劣势,针对这一问题,基于Allan方差分析法,对高成本和低成本的两种MEMS加速度计进行了实测和分析,得到了5项噪声系数,对两种传感器的性能进行了评估和对比,验证了Allan方差方法应用于加速度计误差辨识的可行性,并为加速度计的使用和研究提供了依据.     

一种新型的低成本高性能在线式UPS

提出了一种新型的低成本单相在线不间断电源(UPS)。该系统包括具有功率因数校正(PFC)功能的整流/升压转换器和连接到DC-Link总线的两桥臂逆变器,电池组通过一个非常简单的系统可直接连接到DC-Link总线。采用6开关管的架构,相对于传统的8开关管全桥拓扑结构的系统降低了成本。即使在非线性负载下,该系统仍具有功率密度高和高品质输出电压的特点。最后详细描述了电路操作、分析以及模拟和实验结果。     

A low cost microprocessor based multiple pressure measuring system

A low cost, wide range, six-channel pressure sensor, controlled by a 16-bit microprocessor has been designed and developed. The present design exploits the simplicity and reliability of manometers as well as the acquisition processing and control capabilities of microprocessors. The sensor is of digital output type and hence dispenses with the complex and expensive electronics normally required in conjunction with analogue pressure sensors. The data rate of the developed instrument is six samples/2·5 s for a range of ± 1000 mm of liquid column, with a resolution of 1·1 mm. Accuracy of the present unit is found to be better than 0·2 mm of the liquid column. The hardware and software design and implementation details of the unit are presented in this paper.     

A fast,low cost data acquisition system

A low cost data acquisition system is described for the Apple ][ microcomputer. Two additional cards are necessary, a commercial available timer card and a home-made 12 bits ADC card. Data can be recorded through 4 differential channels with resolutions ranging from 1.2 to 1.2 × 10⁻³ mV/bit. Time intervals between the measurements can range from 1/4 ms to 2 hours.     

A high performance crashworthiness simulation system based on GPU

Crashworthiness simulation system is one of the key computer-aided engineering (CAE) tools for the automobile industry and implies two potential conflicting requirements: accuracy and efficiency. A parallel crashworthiness simulation system based on graphics processing unit (GPU) architecture and the explicit finite element (FE) method is developed in this work. Implementation details with compute unified device architecture (CUDA) are considered. The entire parallel simulation system involves a parallel hierarchy-territory contact-searching algorithm (HITA) and a parallel penalty contact force calculation algorithm. Three basic GPU-based parallel strategies are suggested to meet the natural parallelism of the explicit FE algorithm. Two free GPU-based numerical calculation libraries, cuBLAS and Thrust, are introduced to decrease the difficulty of programming. Furthermore, a mixed array and a thread map to element strategy are proposed to improve the performance of the test pairs searching. The outer loop of the nested loop through the mixed array is unrolled to realize parallel searching. An efficient storage strategy based on data sorting is presented to realize data transfer between different hierarchies with coalesced access during the contact pairs searching. A thread map to element pattern is implemented to calculate the penetrations and the penetration forces; a double float atomic operation is used to scatter contact forces. The simulation results of the three different models based on the Intel Core i7-930 and the NVIDIA GeForce GTX 580 demonstrate the precision and efficiency of this developed parallel crashworthiness simulation system.     

基于LUT的高速低硬件开销SHA-3算法设计

通过对SHA-3算法和查找表(Look-Up-Table,LUT)方法的研究,提出一种高速低硬件开销SHA-3算法设计方案。首先,该方案利用状态机实现SHA-3算法核心置换函数的轮运算,并结合LUT方法处理每轮运算的数据交换和数据存储;然后,采用硬件模块并行处理和存储单元共用的方式,提高SHA-3算法的速度、降低硬件开销。最后,在SMIC 65nm CMOS工艺下设计SHA-3算法,DC综合后电路面积为65 833μm~2,在1.2V电压下最高工作频率可达到150MHz,功耗为2.5mW。     

低成本嵌入式双GPS基准站系统设计

针对高精度GPS定位基准站系统多采用双基准站冗余设备,其系统成本高、缺乏基站独立性的特点,设计了一款低成本嵌入式双GPS基准站系统。该系统内置嵌入式处理器ARM9,选用2套GPS接收机板卡替代主用及备用GPS基准站设备,软件应用Linux操作系统。测试结果表明,该系统在完成播发差分信息的基础上,能根据2套GPS接收机板卡的定位状态自动进行切换,实现双机热冗余,设计主要降低了双基准站系统成本,同时也增加了双机冗余系统的独立性。     

A PZT insulin pump integrated with a silicon microneedle array for transdermal drug delivery

Many of the compounds in drugs cannot be effectively delivered using current drug delivery techniques (e.g., pills and injections). Transdermal delivery is an attractive alternative, but it is limited by the extremely low permeability of the skin. As the primary barrier to transport is located in the upper tissue, Micro-Electro-Mechanical-System (MEMS) technology provides novel means, such as microneedle array and PZT pump, in order to increase permeability of human skin with efficiency, safety and painless delivery, and to decrease the size of the pump. Microneedle array has many advantages, including minimal trauma at penetration site because of the small size of the needle, free from condition limitations, painless drug delivery, and precise control of penetration depth. These will promote the development of biomedical sciences and technology and make medical devices more humanized. So far, most of the insulin pumps being used are mechanical pumps. We present the first development of this novel technology, which can assemble the PZT pump and the microneedle array together for diabetes mellitus. The microneedle array based on a flexible substrate can be mounted on non-planar surface or even on flexible objects such as a human fingers and arms. The PZT pump can pump the much more precision drug accurately than mechanical pump and the overall size is much smaller than those mechanical pumps. The hollow wall straight microneedle array is fabricated on a flexible silicon substrate by inductively coupled plasma (ICP) and anisotropic wet etching techniques. The fabricated hollow microneedles are 200 μm in length and 30 μm in diameter. The microneedle array, which is built with on-board fluid pumps, has potential applications in the chemical and biomedical fields for localized chemical analysis, programmable drug-delivery systems, and very small, precise fluids sampling. The microneedle array has been installed in an insulin pump for demonstration and a leak free packaging is introduced.The support from Ministry of Science and Technology of the People’s Republic of China with contract number of 2005AA40420.     

A high performance hybrid SSVEP based BCI speller system

The existing EEG based keyboard/speller systems have a tradeoff between the target detection time and classification accuracy. This study focuses on increasing the accuracy and probability of target classification rates in the SSVEP based speller system. We proposed two different types of hybrid SSVEP system by combining SSVEP with vision based eye gaze tracker (VET) and electro-oculogram (EOG). Thirty six targets were randomly chosen for this study and their corresponding visual stimulus was presented with unique frequencies. The visual stimuli were segregated into three groups and each group were arranged into different regions (left/middle/right) of the keyboard/speller layout for improving the probability of target detection rate. The VET/ EOG data were utilized to identify the regions that belong to the selected target. The region/group determination decreases the issue of misclassification of SSVEP frequencies. The averaged spelling accuracies of SSVEP-VET and SSVEP-EOG system for all the subjects is 91.2% and 91.39% respectively. Later, a visual feedback was added to the SSVEP-EOG system (SSVEP-EOG-VF) for improving the target detection rate. In this case, an average classification accuracy of 98.33% was obtained with the information transfer rate (ITR) of 69.21 bits/min for all the subjects. An accuracy of 100% was obtained for five subjects with the ITR of 74.1 bits/min in this system.     

基于深亚微米的低成本高可靠BOD电路

经常在MCU等应用系统中遇到系统电源电压出现欠压或意外掉电的情况,导致MCU的程序"跑飞"或丢失重要的数据。为了尽量避免这些情况的出现,掉电检测电路能够检测到系统供电电源异常,以提高系统的抗干扰能力和稳定性。提出一种基于180 nm工艺设计的掉电检测电路,具有结构简单、工作稳定可靠、版图面积小的优点,可集成在MCU等微处理器内部,实现对系统电源电压监测,减少系统的外围器件,降低系统成本。该电路结构可以非常容易地迁移至其他工艺节点,具备良好的工艺迁移特性和应用广泛性。     

Enhancement of PZT embedded swing arm actuator using integrated read/write performance and actuation

The current technological challenges associated with the rotary-type seesaw arm actuator for small-form-factor (SFF) disk drives are the small skew focusing, which causes off-axis aberrations and reduces optical quality. This article develops a novel design for a seesaw arm actuator and suspension assembly that is based on a micro-PZT actuator to position pickup head. Dual-stage actuation relaxes the dynamic requirement on the focusing stroke. The proposed actuator with a tilt-compensation mechanism uses a PZT bender to drive pickup head focusing. This combined system, optical module and dual stage actuator, is effectively self-aligned the optical axis for read/write performance in both experiment and simulation result. Finite element modeling and dynamic measurements reveal significant improvements in the actuator bandwidth with and without micro-PZT actuator compensation.     

A micro gearing system based on a ratchet mechanism and electrostatic actuation

This paper presents the design and fabrication of a silicon micro gearing system (MGS) that utilizes electrostatic comb-drive actuators to rotate a gear ring through a ratchet mechanism. The rotational comb-drive actuator is engaged with the gear ring through a spring system and ratchet teeth at one end, reciprocally rotates around an elastic point at the other end based on the electrostatic force. Rotational motion and torque from the driving gear ring are transmitted smoothly to driven gears through involute-shaped gear teeth. Smart design of anti-gap structures helps to overcome the unavoidable gap problem occurred in deep reactive ion etching (deep-RIE) process of silicon. The MGS has been fabricated and tested successfully by using SOI (silicon-on-insulator) wafer and one mask only. The angular velocity of the gear ring is proportional to the driving frequency up to 40 Hz.     

基于BIM的低成本工程项目进度控制系统设计

针对工程项目中出现的施工进度规划不合理等问题,提出低成本工程项目进度控制系统进行设计。传统的工程项目进度控制方法覆盖面有限,仅可完成某个领域进度的控制,存在成本高,效率低的问题。针对该问题提出基于BIM的低成本工程项目进度控制系统设计方法。该方法首先对控制系统的整体硬件结构进行设计,通过ARM7微处理器以及液晶显示模块、IC总线、以太网模块构建系统硬件组成了整体系统结构。对于所设计的系统软件部分,是基于CSDT-S对TR(传送请求)的处理,结合对TR的处理调度,先实现用户的工程项目进度控制的实时请求,并对其进行响应高效处理,进而利用进度数据信息存储器进行并行分布控制,对获取的控制结果进行进一步整合,按照相关度排序传送到用户的控制界面。为验证所设计系统的有效性,进行一次仿真实验,实验结果表明该系统能够实现人力资源与建筑资源合理分配,并且可以高效控制低成本工程项目管理的具体进度。     

A low cost 3D scanner based on structured light

Automatic 3D acquisition devices (often called 3D scanners) allow to build highly accurate models of real 3D objects in a cost- and time-effective manner. We have experimented this technology in a particular application context: the acquisition of Cultural Heritage artefacts. Specific needs of this domain are: medium-high accuracy, easy of use, affordable cost of the scanning device, self-registered acquisition of shape and color data, and finally operational safety for both the operator and the scanned artefacts. According to these requirements, we designed a low-cost 3D scanner based on structured light which adopts a new, versatile colored stripe pattern approach. We present the scanner architecture, the software technologies adopted, and the first results of its use in a project regarding the 3D acquisition of an archeological statue.     

高性能集群文件系统的研究

集群系统提供了强大的批处理和并行计算的能力,具有高性能、高可扩展性、高吞吐量和易用性等特点,但是I／O性能和处理器性能的不匹配使得I／O成为许多应用的瓶颈,特别是处理大量数据的应用就更是如此。针对集群系统当前的现状,克服该瓶颈的常用方法就是采用一种并行虚拟文件系统（PVFS）技术。随着Linux群集系统性能的持续提高,高速并行文件已成为并行计算的一个必备部分。并行虚拟文件系统（PVFS）为高性能计算（HPC）群集和大型I／O密集并行应用提供了这样一个文件系统。首先介绍了PVFS的结构;然后研究了PVFS的存取和管理机制;最后分析,PVFS的工作原理。     

基于多传感器的高性能监控系统设计

针对传统远程监控系统功能不够全面、性能不够完善等不足,采用ARM处理器和GPRS模块,结合多种传感器,设计了一种高性能远程监控系统。以ARM处理器为数据、视频服务器,实现远程网页监控;采用人体红外传感器感应人体入侵,温湿度传感器采集环境数据,图像传感器采集图像视频数据,GPRS模块负责短信交互与彩信报警。此外,利用背景差分法和改进的Lucy-Richardson(LR)算法对模糊图像进行复原处理。测试结果表明:该系统具有低成本、高性能、功能全面等优点。     

A high performance NAND array file system based on multiple NAND flash memories

The existing NAND flash memory file systems have not taken into account multiple NAND flash memories for large-capacity storage. In addition, since large-capacity NAND flash memory is much more expensive than the same capacity hard disk drive, it is cost wise infeasible to build large-capacity flash drives. To resolve these problems, this paper suggests a new file system called NAFS for large-capacity storage with multiple small-capacity and low-cost NAND flash memories. It adopts a new cache policy, mount scheme, and garbage collection scheme in order to improve read and write performance, to reduce the mount time, and to improve the wear-leveling effectiveness. Our performance results show that NAFS is more suitable for large-capacity storage than conventional NAND file systems such as YAFFS2 and JFFS2 and a disk-based file system for Linux such as HDD-RAID5-EXT3 in terms of the read and write transfer rate using a double cache policy and the mount time using metadata stored on a separate partition. We also demonstrate that the wear-leveling effectiveness of NAFS can be improved by our adaptive garbage collection scheme.     

基于EMD方法的机电作动系统故障特征提取

提出基于经验模式分解(EMD)分析的特征提取方法,该方法自适应地将故障信号分解为不同频段上的基本模式分量(IMF)之和,由于只有少数IMF对故障敏感,从而可以有效提取故障特征。实验结果表明该方法可有效提取电机早期隐性故障特征,为飞机机电作动系统的故障预测和健康评估提供必要的前期准备。