ProfiBus协议的实时性能参数分析

在详细探讨Profibus现场总线数据链路层(MAC)协议的基础上,采用随机Petri网方法对协议令牌循环时间和总线存取效率进行建模分析,着重就协议的实时性能给出了确定随机Petri网(DSPN)模型和性能指标计算方法,并结合实例进行了计算和结果比较.

沥青混合料摊铺机振动振捣装置性能参数分析及设计计算

对沥青摊铺机振动振捣装置进行了参数分析和理论概括 ,为摊铺机振动振捣设计提供了参考。

YTQ-7氧气调节器性能参数调整分析与实验验证

通过对YTQ-7氧气调节器供氧浓度调节原理的分析,说明调整氧浓度调节机构后,在高空输入富氧情况下,可以达到输入纯氧时的供氧浓度要求。经测试并对比分析YTQ-7氧气调节器调整前后供氧性能参数实验数据,验证调整后的氧气调节器供氧性能能够满足不同高度下供氧浓度生理学要求。

水表性能参数的分析及规范性表述

针对各种版本教材和设计手册中对水表技术参数表述不规范、叙述不统一的情况,结合水表生产和使用中所遵循的相关规范和技术标准进行综合分析,归纳和理清水表技术参数的实际含义。并在此基础上,以最新国家标准为依据,结合水表产品样本分析和实际选用过程的需要,提出了关于水表性能参数统一规范化表述的建议,对实践教学和工程设计具有一定的参考价值和指导意义。

ATR/冲压组合动力高超声速飞行器性能分析

针对ATR/冲压并联组合动力的高超声速飞行器,按照典型弹道对其总体性能参数进行计算和分析。结果表明:ATR工作段飞行器的加速性能良好,尤其是在Ma2.0~3.5范围内。总航程随着推重比增加而迅速增加,而飞行时间差别很小,其中ATR工作阶段所占比例显著降低。总航程和飞行时间随着升阻比增加而显著增加,且影响最大的是冲压发动机工作的Ma6.0附近区域。上述研究从飞行器系统角度出发,进一步深化了对ATR发动机的认识。

高大中庭天幕的参数化分析和互动性遮阳节能设计研究——以湖南长沙LIVE项目S2地块为例

以湖南长沙LIVE项目S2地块为例,引入建筑性能参数化分析,采用集参数化建模、气象数据分析、多环境性能模拟于一体的Rhino及Grasshopper软件,分析最适用于本项目中庭玻璃顶棚的遮阳设计及材质,解决温室效应与烟囱效应带来的过热问题,并对比了传统的被动式遮阳与新兴的主动式数字互动遮阳两种方案,进一步协调建筑、环境与人的关系,为使用者提供更好的生活体验。

面向空间天线的TWF复合材料性能研究

利用碳纤维三向编织物(triaxial woven fabric,TWF)作为增强材料,与柔性基体材料硅橡胶复合,制成兼具一定柔性和刚性的复合材料壳膜结构,用于卫星天线反射器,是一种新型的高精度可展开天线实现方案。采用复合材料细观方法,对碳纤维增强硅橡胶TWF复合材料进行了力学性能的研究。首先由纤维和基体的材料特性得到均质纤维束的材料特性;接下来考虑纤维束交织情况(起伏波动)建立由纤维束组成的单胞实体有限元模型;然后对单胞实体有限元模型进行均匀化分析,施加周期性边界条件,最终得到等效的均质材料特性;为满足天线反射器高性能需求,分析了碳纤维种类、纤维体积分数对单胞等效性能的影响规律。对该材料力学性能的研究,可以为其未来应用于大型高精度可展开天线反射器提供一定的理论依据。

往复压缩机多故障试验模拟及特征分析

为了解往复压缩机不同结构故障和性能故障的参数特征,对WP135型压缩机部件典型故障进行了模拟,包括地脚螺栓松动、活塞环断裂、吸气阀片断裂、排气阀片断裂。通过分析不同故障下的压缩机热工参数和缸盖顶部、机身侧面、机身底部测点振动信号的时域波形、时域、频域特征参数,揭示了热工参数和表面振动信号与压缩机不同零部件故障的内在联系。结果表明:不同的性能故障具有不同的热工参数变化特征,可以利用这些参数进行压缩机一级活塞环密封不良、二级活塞环密封不良、二级进气阀片断裂、二级排气阀片断裂性能故障的诊断。压缩机表面的振动对压缩机结构故障较敏感,可以用于对地脚螺栓松动故障的诊断,也可以利用振动信号的频谱特征进行其它结构故障的诊断,为进行往复式空压机的状态监测和健康管理提供了依据。

自动喷水灭火系统性能及其在建筑消防中的应用研究

以陕西省西安市某建筑工程自动配水灭火系统设计为研究对象,采用图表分析方法对自动喷水灭火系统的喷水系数进行分析,结合工程实例对不同喷水系数条件下的最不利管段水力进行计算。结果表明,无论是在何种建筑场合,采用自动喷水灭火系统的灭火成功率均≥90%;在同一喷头系数条件下,自动喷水灭火系统中节点喷头进口端的工作水压力随着喷头流量的增加而增加;在同一喷头工作压力条件下,自动喷水灭火系统中节点喷头流量与喷头系数呈正比;基于自动喷水灭火系统性能的最不利管段水力计算分析可以对管段和喷头的水力压力、水流量以及总水头损失进行分析。

百万千瓦压水堆核电站安全壳喷淋泵分析对比

安全壳喷淋泵是核电站安全壳喷淋系统(EAS)的组成部分,通过对国产、国外安全壳喷淋泵在水力设计、结构设计和各细部设计的分析对比,得出核电站安全壳喷淋泵研制的新思路。

Mechanical behaviors of steel reinforced ECC / concrete composite columns under combined vertical and horizontal loading

In order to improve the load capacity, seismic performance and performance-cost ratio of the columns, the concrete at the base of reinforced concrete （RC） columns is substituted with engineered cementitious composites （ECC） to form ECC/RC composite columns. Based on the existing material properties, the mechanical behaviors of the ECC columns, ECC/RC composite columns and RC columns were numerically studied under combined vertical and horizontal loading with the software of ATENA. Then, the failure mechanism of ECC columns and ECC/RC composite columns were comprehensively studied and compared with that of the RC columns. Then, the effects of the height of the ECC, the axial compression ratio, and the transverse reinforcement ratio on the mechanical behaviors of the composite or the ECC column are studied. The calculation results show that the ultimate load capacity, ductility and crack resistance of the ECC or ECC/RC composite columns are superior to those of the RC columns. The ECC/RC composite column with a height of the ECC layer of 1.2h （ h is the height of the cross section） can achieve similar mechanical properties of a full ECC column. With high shear strength, ECC can undertake the shear force and significantly reduce the amount of stirrups, avoiding construction issues and promoting its engineering application.

Parametric analysis on buffeting performance of a long-span high-speed railway suspension bridge

The buffeting performance of kilometer-level high-speed railway suspension bridges has a great impact on the smooth operation of high-speed trains.To investigate the buffeting performance of the structure significantly different from traditional suspension bridges,the first long-span high-speed railway suspension bridge,Wufengshan Yangtze River Bridge(WYRB),is taken as a numerical example to demonstrate the effects of structural parameters and wind field parameters on the buffeting responses.Based on the design information,the spatial finite element model(FEM)of WYRB is established before testing its accuracy.The fluctuating wind fields are simulated via both classical and stochastic wave based spectral representation method(SRM).Finite element method is further taken to analyze the parametric sensitivity on wind induced buffeting responses in time domain.The results show that the vertical displacement is more sensitive to the changing dead load than the lateral and torsional ones.The larger stiffness of the main girder and the lower sag-to-span ratio are both helpful to reduce the buffeting responses.Wind spectrum and coherence function are key influencing factors to the responses so setting proper wind field parameters are essential in the wind-resistant design stage.The analytical results can provide references for wind resistance analysis and selection of structural and fluctuating wind field parameters for similar long-span high-speed railway suspension bridges.

Seismic behaviors of steel reinforced ECC/RC composite columns under low-cyclic loading

To improve the seismic performance of columns, engineered cementitious composite （ECC） is introduced to partially substitute concrete at the base of the columns to form ECC,/reinforced concrete （ RC） composite columns. The mechanical behaviors of the ECC/RC composite columns are numerically studied under low-cyclic loading with the finite element analysis softwareof MSC. MARC. It is found that the ECC/RC composite columns can significantly enhance the load capacity, the ductility ad energy dissipation of columns. Then, the effects of the height of the ECC, the axial compression ratio and the longitudinal reinforcement ratio on the seismic behaviors of the composite columns are parametrically studied. The results show that the ECC/RC composite column with a height of the ECC layer of 0. Sh（h is the height to the cross-section） can achieve similar seismic performance of a full ECC column. The peak load of the composite column increases significantly while the ductility decreases with the increase of the axial compression ratio. Increasing the longitudinal reinforcement ratio within a certain range can improve the ductility and energy dissipation capacity and almost has no effect on load capacity. The aalysis results ae instructive and valuable for reference in designing ECC structures.

Hydration process of rice husk ash cement paste and its corrosion resistance of embedded steel bar

Thermogravimetric analysis and electrical resistivity were used to determine the hydration process of cement paste with rice husk ash(RHA)(0−15%)and water-cement ratio of 0.4 in this work.X-ray diffraction(XRD)method and scanning electron microscopy(SEM)were used to survey crystal composition and microstructures of specimens cured for 3 h,1 d,7 d and 28 d.Finally,electrical parameters(electrical resistance and AC impedance spectroscopy)of steel bars reinforced cement paste were investigated to study the effect of RHA on the corrosion resistance.Results showed that RHA could affect the cement hydration by hydration promotion and pozzolanic effect.The evaluation function for electrical resistivity and curing ages fitted well with linear increasing function.The addition of RHA higher than 5%demonstrated a decreasing role in the electrical resistivity of cement paste at earlier curing ages(3−7 d).Meanwhile,when at later curing ages(7−28 d)the result was the opposite.Moreover,RHA demonstrated positive effects on corrosion resistance of steel bars in cement paste.

Parameter design and performance analysis of zero inertia continuously variable transmission system

In order to solve the problem of weak power performance of vehicle equipped with continuously variable transmission(CVT) system working under transient operating conditions, a new CVT equipped with planetary gear mechanism and flywheel was researched, a design method of transmission parameter optimization was proposed, and the comprehensive matching control strategy was established for the new transmission system. Fuzzy controllers for throttle opening and CVT speed ratio were designed, and power performance and fuel economy of both vehicles respectively equipped with conventional CVT system and new transmission system wrere compared and analyzed by simulation. The results show that power performance and fuel economy of the vehicle equipped with new transmission system are better than that equipped with conventional CVT, thus the rationality of the parameter design method and control algorithm are verified.

Study on hydrostatic gas lubricated non-contacting mechanical seal

The principle and characteristics of hydrostatic gas lubricated non-contacting mechanical seal （HSGLNMS） are introduced. The flow field of the gas film is established by numerical analysis of end faces of HSGLNMS. The distribution of gas film pressure and seal performance parameters inclu- ding opening force and leakage are obtained. Influence of operating parameters and sealing configu- ration on the sealing performance is studied. HSGLNMS has been designed and manufactured. Its working film thickness and leakage are measured to verify the theoretical analysis. The investigation results show that HSGLNMS demonstrates good speed adaptability, which means that the seal runs successfully with both low and high speed, showing excellent performance. The seal can be regula- ted and controlled online ; the opening force will not be raised greatly with the increasing of the num- ber of throttle orifices, but the leakage of seal increases apparently ; the uniform pressure groove im- proves the sealing performance, for example, opening force and stiffness are raised obviously. While leakage is reduced. Finally, the theoretical analysis is verified by experiment.

Performance Analysis and Design of Vertical Axis Tidal Stream Turbine

This study numerically analyzes the unsteady flow around the Darrieus-type turbine by using FLUENT and deals with the application to the design of blades. Two kinds of blade sections were used in this study. Unsteady RANS equation and the turbulence model, either k-e or k-co model, which are appropriate for each blade section, were employed. First for the NACA 634-021 blade that the experimental data is available, the 2-dimensional and 3-dimensional numerical analyses have been performed and compared with the experimental result. For the optimization of the turbine, the parametric study has been performed to check the performance in accordance with the changes in the number of blades, solidity and camber. It is demonstrated that the present approach could draw the turbine characteristics better in performance than the existing turbine. Next for the NACA 653-018 blade with the high lift-drag ratio from the purpose of developing highly-efficient turbine, this study has also tried to get the highly efficient turbine specifications by analyzing the performance while using 2-dimensional and 3-dimensional numerical analyses and the result was verified through the experiment. According to the present study, it is concluded that the 3-dimensional numerical analysis has simulated the experimental values relatively well and also, the 2-dimensional analysis can be a useful tool in the parametric study for the turbine design.

Influences of the Suspension Parameters on the Vehicle Suspension Performance for a Terrain Vehicle

This paper describes an effective methodology for evaluation of the suspension parameters intended to be used for a terrain vehicle. The objective of this approach is to make quick analyses of the sensitivity of the vehicle suspension parameters. For the purpose of developing such a methodology, a mathematical modeling of a quarter vehicles suspension system is developed. Sensitive analysis of the suspension parameters is performed by employing the standard deviation of the vehicle body acceleration, dynamic tire load, and suspension travel. Sensitivity analysis results have shown that the spring stiffness, damping coefficient, tire stiffness and sprung mass have substantial influence on the ride comfort and road holding, while un-sprung mass on the other side has much lower impact in performance of the vehicle suspension system.

Investigate the Parameters Effect on Thermogravimetry Analysis （TGA） Performance for SOx Additive in FCC Units

Although the FCC process has been used for more than halfa century, new and important developments continue to be made in several areas. Some of these new developments are a direct response to environmental regulation. Sulfur oxides （SOx-SO2＋SO3） emitted from fluid catalytic cracking units （FCCU） are one of the most hazardous atmospheric pollutants, which may cause serious environmental problems such as the formation of acid rain and the destruction of the ozone layer. Thus, great attention has been focused on the SOx removal from FCC in last few years. The present papers will focus on the spinel material studies include three samples they were prepared by acidic method, solid solution MgAl2O4, solid solution with cerium10%Ce/MgAl2O4, iron mixed spinel with cerium 10%Ce/MgAl2-xFeO4.MgO and two samples solid solution with cerium introduce by vanadium as second co-catalyst prepared by basic method, 1% V/10%Ce/MgAl2O4.MgO were tested in TGA for oxidation half cycle to study some parameters effect on performance of SOx additives in TGA under condition similar to those of FCC units. Thermogravimetry analysis experiments have been used to demonstrate the pick-up and release of sulfur oxides in the development of additives for SOx control in the FCCU.

Performance Behaviour Analysis of the Present 3-Level Cache System for Multi-Core Processors

In this paper, a study related to the expected performance behaviour of present 3-level cache system for multi-core systems is presented. For this a queuing model for present 3-level cache system for multi-core processors is developed and its possible performance has been analyzed with the increase in number of cores. Various important performance parameters like access time and utilization of individual cache at different level and overall average access time of the cache system is determined. Results for up to 1024 cores have been reported in this paper.