急诊PCI与择期PCI治疗急性心肌梗死的临床对比分析

目的 :观察急诊PCI与择期PCI治疗急性心肌梗死的临床疗效,探讨急诊PCI治疗急性心肌梗死的临床价值及优越性。方法 :对急诊PCI与择期PCI治疗的心肌梗死患者的临床资料进行回顾性分析,观察两组临床疗效、心脏事件发生率及心肌改善情况。结果 :急诊PCI组的治愈率为63.41%,明显高于择期PCI组的48.15%(P<0.05);急诊PCI组患者住院期间心脏事件总发生率为4.88%,明显低于择期PCI组的22.22%(P<0.05);急诊PCI组住院时间明显低于择期PCI组(P<0.05);急诊PCI组术后左心室射血分数明显高于择期PCI组(P<0.05);两组患者随访期间心脏事件发生率及死亡率比较均无显著差异(P>0.05)。结论 :急诊PCI治疗急性心肌梗死的疗效优于择期PCI治疗,患者一旦确诊为心肌梗死,应尽早行PCI治疗,以最大限度地挽救心肌缺血,降低心脏事件及死亡率。     

PCI2040与TMS320C5410的接口设计

PCI2040是TI公司推出的专门用于DSP和PCI总线的接口芯片。能够实现PCI总线和TI公司的DSP的HPI口的无缝连接，最多可连接四片DSP至PCI总线。本文主要介绍了PCI2040与TMS320C5410的一种连接方式，并给出一个应用实例。     

一种可工作在66MHz环境下PCI core的研究

对PCI接口控制芯片和PCI总线信号和操作进行了介绍.详细分析了一种当今流行的PCIcore(PCI核心控制模块)结构设计.本文结合PCI总线的详细传输流程详细地分析了PCI从设备(PCISlave)控制模块的有限状态自动机.同时提出了利用FPGA实现该设计的测试方案.     

一种新型的PCI-GPIB数据采集卡的实现

PCI-GPIB卡在工业现场得到了广泛应用,PCI-GPIB卡本质上说就是从PCI协议到GPIB协议的转换。本文介绍了PCI-GPIB数据采集卡的硬件实现．本设计采用PCI接口芯片PCI9052开发PCI接口,用外部级联FIFO加深数据通道深度．用CPLD完成GPIB接口的控制和数据传输控制。     

基于FPGA的PCI接口IO卡设计

通过研究PCI总线规范,详细介绍了利用Altera公司的Cyclone系列FPGA设计PCI总线IO卡的过程,实现了33MHz、32位的PCI总线协议,并给出用FPGA控制32入、32出IO接口卡电路和设计PCI总线驱动程序的方法。     

基于PCI9052的CAN总线设计

本文介绍了PCI接口芯片PCI9052和CAN接口芯片SJA1000,给出了基于PCI总线的CAN总线适配卡软硬件的设计思路、过程及实现方法。     

基于DSP的液体药品灌装机的运动控制卡设计

介绍了一种采用PCI专用接口芯片PCI9052作为PCI总线与DSP(TMS320LF2407)的接口桥接器,实现液体灌装机2轴运动控制卡的硬件设计方法.首先给出了运动控制卡的总体硬件结构,包括PCI总线接口规范、DSP扩展电路.其次,提出了模糊PID算法在其中的应用.通过PCI与DSP结合的方法,实现了控制器与上位机的高速通讯,充分发挥了DSP电机控制芯片计算速度快,功能强大的特点,提高了灌装精度.     

基于DSP的液体药品灌装机的运动控制卡设计

介绍一种采用PCI专用接口芯片PCI9052作为PCI总线与DSP(TMS320LF2407)的接口桥接器,实现液体灌装机2轴运动控制卡的硬件设计方法。首先给出了运动控制卡的总体硬件结构,包括PCI总线接口规范、DSP扩展电路;其次,提出了模糊PID算法在其中的应用。通过PCI与DSP结合的方法,实现了控制器与上位机的高速通信,充分发挥了DSP电机控制芯片计算速度快、功能强大的特点,提高了灌装精度。     

基于嵌入式X-Board的PCI-CAN采集卡的设计

介绍了基于嵌入式X-BOARD计算机的PCI总线转CAN总线智能适配卡原理及设计方案,包括PCI总线接口的配置的一个简单实例以及在嵌入式系统中对PCI设备进行操作的基本方法,以及CAN总线节点控制软件设计的基本流程。     

PCI设备的WDM驱动程序设计

本文详细地讨论了利用DDK开发PCI设备的WDM驱动程序的设计原理，方法及在设计中注意事项，实现了以芯片PCI9052开发的PCI卡的具有内存和I/O读写及中断处理的WDM驱动程序。     

CHARACTERISTCS OF FLUID FILM IN OPTIMIZED SPIRAL GROOVE MECHANICAL SEAL

In order to investigate the sealing performance variation resulted from the thermal deformation of the end faces, the equations to calculate the fluid film pressure distribution, the bearing force and the leakage rate are derived, for the fluid film both in parallel gap and in wedgy gap. The geometrical parameters of the sealing members are optimized by means of heat transfer analysis and complex method. The analysis results indicate that the shallow spiral grooves can generate hydrodynamic pressure while the rotating ring rotates and the bearing force of the fluid film in spiral groove end faces is much larger than that in the flat end faces. The deformation increases the bearing force of the fluid film in flat end faces, but it decreases the hydrodynamic pressure of the fluid film in spiral groove end faces. The gap dimensions which determine the characteristics of the fluid film is obtained by coupling analysis of the frictional heat and the thermal deformation in consideration of the equilibrium condition of the bearing force and the closing force. For different gap dimensions, the relationship between the closing force and the leakage rate is also investigated, based on which the leakage rate can be controlled by adjusting the closing force.     

CURING PROCESS OF PHOTOPOLYMER RESIN BOND DIAMOND TOOLS

Analytical simulation and corresponding proof-test are adopted to study the principle of the curing process of photopolymer resin diamond tools. The influence of the diamond as abrasives in photopolymer resin owing to the absorptivity of the diamond for the UV light on the photopolymer resin curing process is discussed. Based on the above, a kind of diamond tool—dicing blade is selected to analyze the curing process of photopolymer bond diamond tools. An analytical model of curing process is developed and a correlation curve between the depth of polymerization of the photopolymer resin diamond tools and the exposure time to represent the curing process of photopolymer bond dicing blade. A test is done to proof-test the validity of the analytical model and the correlation curve. The simulated data fit the experimental results, which demonstrates the analytical models and numerical algorithm are of high reliability. The analytical simulation method could possibly be used to optimize the curing cycle and improve the quality of the photopolymers resin bond diamond tools.     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

Effects of prebuckling deformations on the elastic flexural-torsional buckling of laterally fixed arches

The effect of the prebuckling in-plane deformations on the elastic flexural-torsional buckling of laterally fixed circular arches is studied in this paper. The finite strains and the energy equation for the flexural-torsional buckling of arches have been derived based on an accurate orthogonal rotation matrix. A closed form solution for the elastic flexural-torsional buckling resistance of laterally fixed arches in uniform bending, including the effects of the prebuckling deformations, is obtained. It is found that the notion that the prebuckling deformations increase the flexural-torsional buckling moment of an arch or of a beam is not necessarily correct for a laterally fixed arch or beam in uniform bending, in deference to a laterally pinned arch. When a laterally fixed arch is subjected to positive uniform bending, the effects of the prebuckling deformations decrease the buckling moment, and the reduction of the buckling moment increases with an increase of the included angle and of the out-of-plane slenderness ratio of the arch. When a laterally fixed arch is subjected to negative uniform bending, the effects of the prebuckling deformations decrease the absolute value of its buckling moment when the included angle is very small, but increase the absolute value of the buckling moment when the included angle exceeds a certain value. The increase in the absolute value of the buckling moment increases with an increase of the included angle and of the out-of-plane slenderness ratio of the arch. When the ratio of the out-of-plane to the in-plane second moments of area of the cross-section is not small, both the reduction of the buckling moment of a laterally fixed arch in positive uniform bending and the increase of the buckling moment of a laterally fixed arch in negative uniform bending, are substantial.     

PHENOMENON OF CARVED DRIVING WHEELS

A newly found phenomenon of carved driving wheels of a rear-wheel-drive tractor used in an airport is discussed. The circum of every driving wheel is damaged at three regions,which distribute regularly and uniformly. Everyday,the tractor tows a trailer which are times heavier than the tractor,and moves on the same road in the airport. The phenomenon is explained by the torsional self-excited vibration system of the powertrain. The simplified torsional vibration system is discribed by a 2-order ordinary differential equation,which has a limit circle. Experiments and numerical simulations show the followings: Because of the heavy trailer,the slip ratio of the tractor’s driving wheels is very large. Therefore,there is severe torsional self-excited vibration in the tractor’s drivetrain,and the self-excited vibration results in severe and regular fluctuations of the rear wheel’s velocity. The severe fluctuations in velocity fastens the damage of the driving wheels. At the same time,the time interval in which an arbitrary point in the circum of the driving wheel contacts with the road twice is two times more than the period of the torsional self-excited vibration,and this times explained the existence of three damaged regions. At last,it points out that the phenomenon can be avoided when the torsional damping is large enough.     

OPTIMIZATION METHOD ON IMPELLER MERIDIONAL CONTOUR AND 3D BLADE

An optimization method for 3D blade and meridional contour of centrifugal or mixed-flow impeller based on the 3D viscous computational fluid dynamics (CFD) analysis is proposed. The blade is indirectly parameterized using the angular momentum and calculated by inverse design method. The design variables are separated into two categories: the meridional contour design variables and the blade design variables. Firstly, only the blade is optimized using genetic algorithm with the meridional contour remained constant. The artificial neural network (ANN) techniques with the training sample data schemed according to design of experiment theory are adopted to construct the response relation between the blade design variables and the impeller performance. Then, based on the ANN approximated relation between the meridional contour design variables and impeller performance, the meridional contour is optimized. Fewer design variables and less calculation effort is required in this method that may be widely used in the optimization of three-dimension impellers. An optimized impeller in a mixed-flow pump, where the head and the efficiency are enhanced by 12.9% and 4.5% respectively, confirms the validity of this newly proposed method.     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

运用改进残余力向量法的结构损伤识别研究

针对结构损伤识别时测试结构模态振型不完备的情况,采用了自由度凝聚方法进行模型凝聚,并给出了缩聚模型的残余力向量计算公式,证明了残余力向量对结构损伤单元的敏感性.为减小自由度凝聚及测量等因素带来的误差影响,提出了一种改进的残余力向量法.该方法首先通过测试损伤结构多阶模态得到残余力向量,并计算相对于损伤前结构的残余力向量得到残余力向量差矩阵,选取向量差矩阵各行元素中最大绝对值组成改进的残余力向量.损伤识别时,先运用改进的残余力向量确定可能损伤单元,再运用筛选法计算单元损伤程度.数值仿真算例说明,采用该方法只需结构的前几阶低阶频率和振型,就可以快速准确地识别出结构的损伤,显示了该方法具有较好的抗噪性.     

EFFECTS OF INJECTION STRATEGY ON D.I. DIESEL ENGINE COMBUSTION

Experiments are conducted to develop an understanding of how split injections can affect the combustion and emission characteristics of a D.I. diesel engine with a common-rail injection system. The ratio of the amount of fuel injected between two injection pulses and the injection interval is varied keeping the injected fuel quantity constant. Results show that under the 70D90-10 injection pattern, the engine achieves the lower NOx-smoke emissions and BSFC compared with the single injection pattern. The heat release rate and the temperature show that the split injections increase the initial premixed burn and retards the diffusion burn. With the balance of these two effects, the maximum in-cylinder temperature decreases while the 50% heat release point is held at almost the same crank angle. Therefore, both NOx emission and BSFC are improved while keeping the smoke emission at the same level.     

DESIGN AND CAD SYSTEM OF THE FOOL FOR DRILL FLUTE

Based on the principles of differential geometry and kinematics, a mathematical model is developed to describe the grinding wheel axial cross-section with the radial cross-section of the flute in a given drill under the basic engagement condition between the generating flute and the generated grinding wheel (or disk milling tool). The mathematical model is good for the flute in the radial cross-section consisting of three arcs. Furthermore, a CAD system is also developed to represent the axial cross-section of the grinding wheel (or disk milling tool). With the system, the grinding wheel (or disk milling tool) axial cross-section that corresponds to the three-arc flute cross section can be conveniently simulated. Through the grinding experiment of drill flutes, the method and the CAD system are proved to be feasible and reasonable.