汽车发动机ECU的可靠性试验研究

针对国内某型汽车发动机电子控制单元(ECU)自主研发关键技术,开展了ECU可靠性试验研究.根据相关可靠性试验标准及汽车发动机ECU的具体特性,研究了ECU可靠性筛选试验、可靠性增长试验和可靠性鉴定试验的试验原理和实施流程,开发了ECU可靠性试验系统,并制订出详细的ECU可靠性联合试验方案.在此基础上,对国内某型汽车发动机ECU进行了现场试验.试验结果表明:试验系统平台设计合理,试验方案可行,经过试验的ECU样品,其平均寿命MTTF得到较大幅度增长,可靠性水平得到显著提高.     

机车车辆部件的振动试验

介绍了铁路机车车辆部件振动试验的必要性,简述正弦振动试验和随机振动试验的概念和试验要点,给出了一个随机振动和冲击试验的实例。     

发动机性能台架试验自动化系统的开发

开发了发动机性能台架试验自动化系统,包括发动机台架标定和性能开发试验自动化运行系统、发动机台架试验实时控制系统、发动机试验保护策略和系统、发动机台架试验测量系统不确定度评定、试验台架传动系统扭转振动校核等。将自动化系统应用于试验项目,实现了发动机台架标定和性能开发试验的完全自动化,提升了试验效率和质量,加快项目开发进度。     

核电工程试验的过程控制

遵从核电质量保证对工程研究开发的规定,以及基于核电工程试验的实施过程具有质量保证中规定的"特殊过程"的基本特征,提出了核电工程试验成功的标志与主要准则.从试验目标和质量保证2个角度,明确了核电工程试验各个阶段的控制要素和进行验证的要求.对试验设施可用性验证是试验过程控制的最重要环节,正式试验之前必须验证和确认试验模型特征量正确、关键参数测量准确、工况保障条件可控、质/能平衡测定合格和典型工况试验结果合理,以确保试验数据有足够的置信度.在国家大型先进压水堆核电站重大专项关键试验项目中,已全面实施了这种过程控制的相关程序,有效地促进了试验成功.     

直接空冷岛的性能验收试验标准的应用分析

国内的空冷岛验收试验目前基本上采用国外VGB导则进行.对国内、国外空冷岛验收试验标准进行了比较,分析了各自的优点及缺点.结合某国内600MW机组空冷岛的验收试验,对空冷岛试验的重点进行了阐述.可供相关生产及试验单位参考.     

缩短6110柴油机出厂试验时间的研究

介绍了无锡柴油机厂通过对传统产品6110柴油机的出厂试验进行研究,选择磨合油,同时科学制订磨合规范,并将新旧出厂试验用油及磨合规范进行对比试验研究,最终确立了行之有效的、明显缩短了出厂试验时间的试验程序及试验用油,提高了工作效率及经济效益,且满足了工厂产能扩大的需要.     

混凝土直拉试验和三点弯曲断裂试验确定的软化曲线的比较

通过混凝土材料直拉和弯曲试验,分别取得了混凝土拉伸软化曲线,并对比分析了直拉试验和三点弯曲断裂试验结果。结果表明,直拉试验所得受拉峰值应力较三点弯曲断裂试验小,这是因为在三点弯曲断裂试验中,应变梯度提高了混凝土的受拉峰值应变,从而提高了受拉峰值应力;直拉试验所得断裂能比三点弯曲断裂试验略大。总体上看,两种试验所得混凝土软化关系相近。因此,三点弯曲断裂试验可代替直拉试验获得混凝土拉伸软化曲线。     

适用于小型热气机性能试验的电加热器的研制

介绍了一种针对小型家用热气机性能试验开发的电加热器系统.该电加热器可以模拟性能试验时外燃系统对热头的加热情况,精确控制输入的热量.针对不同材料不同形式的加热器进行理论试验研究,确定并制造了应用于试验的电加热器系统.试验验证了其可行性,可满足家用小型热气机性能试验的要求.     

轴承巴氏合金磨损试验的优化设计

在MG-2000摩擦磨损试验机上采用改进的环环试验方法进行巴氏合金与轴颈材料对磨试验,通过对试样优化设计,确定了试样的最佳尺寸和形状,改进了试验方法。试验结果与工程实际情况相吻合,该试验方法和所确定的试样形式和尺寸适合用于汽轮机大型滑动轴承边界润滑状态下的巴氏合金磨损试验。     

基于非稳定流抽/压水试验的岩体渗透系数求解方法

针对传统抽水试验和Lugeon压水试验的不足,在同一钻孔内分别进行了分段压水试验和完整井抽水试验,并根据两种试验得到了试验钻孔处渗透系数剖面分布,分析了采用非稳流压力法测量岩体渗透系数的可行性和准确性。结果表明,压水试验与抽水试验的渗透系数并无显著差异,尤其非稳定流压水试验所需的试验时间更短,其所要求的试验条件易于获得,且准确性和可操作性更优。     

Type II Thermoelasticity. A New Aspect

In this paper we investigate the thermomechanical theory of thermoelasticity without energy dissipation. We consider the case where the assumptions on the constitutive tensor are different from the usual ones in the current literature. These assumptions are suitable because they correspond to situations where the material is prestressed and has initial entropy flux. When we restrict our attention to the one-dimensional problem, we first establish a condition on the coefficients to guarantee the hyperbolicity of the system. Then we prove that the problem is well posed and stable. When the hyperbolicity condition is not satisfied we prove that the problem is ill-posed. We also prove a similar result when the dimension is greater than one whenever the domain satisfies a certain condition. Though we cannot expect in general the stability of solutions in dimension greater than one, we prove the uniqueness and stability of radial solutions in the general case. To obtain the results, we need the use of a conservation law which has not previously been considered in the literature. Similar results are not known for other thermoelastic theories.     

Maximum thermodynamic power coefficient of a wind turbine

According to the centenary Betz‐Joukowsky law, the power extracted from a wind turbine in open flow cannot exceed 16/27 of the wind transported kinetic energy rate. This limit is usually interpreted as an absolute theoretical upper bound for the power coefficient of all wind turbines, but it was derived in the special case of incompressible fluids. Following the same steps of Betz classical derivation, we model the turbine as an actuator disk in a one dimensional fluid flow but consider the general case of a compressible reversible fluid, such as air. In doing so, we are obliged to use not only the laws of mechanics but also and explicitly the laws of thermodynamics. We show that the power coefficient depends on the inlet wind Mach number , and that its maximum value exceeds the Betz‐Joukowsky limit. We have developed a series expansion for the maximum power coefficient in powers of the Mach number that unifies all the cases (compressible and incompressible) in the same simple expression: .     

某柴油机系列机型曲轴轴向间隙偏小分析与改进

通过对设计图纸标注尺寸的尺寸链计算,及对大量装配数据的统计分析,发现对于柴油机止推瓦这种结构,在装配后上、下轴瓦间必定会产生约0.05 mm左右的错位量,在尺寸链计算时必须将这个错位量当做减环来处理,否则就会出现大量不合格。     

某柴油机辐射噪声仿真分析

为降低某柴油机的整机噪声,采用数字化设计方法对其进行了仿真分析,基于AVL Excite平台建立了整机多体动力学模型,结合多体动力学结果对整机结构进行了进一步的数据恢复和声学分析,得到了整机的表面振动速度和辐射声功率级。针对噪声突出频率,找出了最大噪声源为油底壳,为整机降噪指明了方向。     

Measurement of spectra over the Bolund hill in wind tunnel

We have determined the normal Reynolds stresses and spectra of the wind velocity over a 1:115 scale mock‐up of the Bolund hill. The experiment was run in a neutral boundary layer wind tunnel using 3‐component hot‐wire velocimetry, 2‐component particle image velocimetry, and a high‐precision traversing system. Spectra have been determined at different points along transects at 2 and 5 m height above ground level. The experiment was run for 270° wind direction and for two Reynolds numbers, and , based on the maximum height of the hill and the free wind speed at this height. Our results show how the normalized power spectral density changes over the hill. The analysis of the normalized streamwise spectrum at 2 m height, just after the escarpment, reveals that part of the energy is concentrated in the interval of normalized frequencies n_h≈0.01?0.02, which could be a signature of a weakened “flapping” phenomenon described in the literature for flows over forward facing steps. The departure of the spectra slope in the inertial subrange, from the value ?5/3, was found to be correlated with the hill geometry.     

Oil and pump prices: Testing their asymmetric relationship in a robust way

The aim of this study is to provide a novel method to assess whether retail fuel prices respond asymmetrically to changes in the international crude oil prices. To do so, we consider the whole supply chain, we use daily data and we depart from the current practice in the literature that focuses on prices. Rather, we consider the mark-ups of both the refineries and retailers. Hence, we show that we first need to assess whether the refineries' mark-up responds asymmetrically to the international crude oil prices and subsequently whether the retailers' mark-up shows an asymmetric behaviour relatively to changes in the refined fuel prices. Focusing in Greece as our case study, our findings show that Greek fuel retailers do not change their mark-up behaviour based on changes of the refined fuel price. By contrast, the asymmetric behaviour is evident in the refineries' mark-up relatively to changes in the international crude oil prices, which is then passed through to the retailers and consumers. Finally, we provide evidence that weekly and monthly data mask any such asymmetric relationship. Thus, we maintain that unless the appropriate data frequency, fuel price transformations and the whole supply chain are considered, misleading findings could be revealed.     

天然气储量最优经济评价方法研究

在油气田对天然气储量经济性评价中,主要是对天然气储量经济性评价指标如内部收益率、财务净现值、投资回收期的计算。而油气田在对天然气储量经济性评价中,由于受资料的限制,往往难以进行准确的评价。为此,运用净现值分析方法,结合油气田天然气储量收益、收益性支出和投资情况,通过对天然气产量变化规律的认识,建立油气田天然气初始经济产量的数学模型,以确定应达到的最低投产数量,才能保证内部收益率的实现。     

On a Thermodynamic Theory of Porous Cosserat Elastic Shells

This paper presents a theory for porous thermoelastic shells using the model of Cosserat surfaces and the Nunziato–Cowin theory for materials with voids. To describe the porosity of the thin body, we introduce two scalar fields: one field accounts for the changes in volume fraction along the middle surface of the shell, and the other field characterizes the porosity variations along the shell's thickness. First, we postulate the principles of thermodynamics for these two-dimensional continua and we obtain the equations of the nonlinear theory. Then, we consider the linearized theory and prove the uniqueness of solution to the boundary initial value problem with no definiteness assumption on the constitutive coefficients. Finally, we consider the deformation of isotropic and homogeneous shells and determine the constitutive coefficients for Cosserat surfaces, by comparison with the results obtained from the three-dimensional approach to shell theory.     

Aerodynamic optimization of wind turbine rotors using a blade element momentum method with corrections for wake rotation and expansion

The blade element momentum (BEM) method is widely used for calculating the quasi‐steady aerodynamics of horizontal axis wind turbines. Recently, the BEM method has been expanded to include corrections for wake expansion and the pressure due to wake rotation (), and more accurate solutions can now be obtained in the blade root and tip sections. It is expected that this will lead to small changes in optimum blade designs. In this work, has been implemented, and the spanwise load distribution has been optimized to find the highest possible power production. For comparison, optimizations have been carried out using BEM as well. Validation of shows good agreement with the flow calculated using an advanced actuator disk method. The maximum power was found at a tip speed ratio of 7 using , and this is lower than the optimum tip speed ratio of 8 found for BEM. The difference is primarily caused by the positive effect of wake rotation, which locally causes the efficiency to exceed the Betz limit. Wake expansion has a negative effect, which is most important at high tip speed ratios. It was further found that by using , it is possible to obtain a 5% reduction in flap bending moment when compared with BEM. In short, allows fast aerodynamic calculations and optimizations with a much higher degree of accuracy than the traditional BEM model. Copyright © 2011 John Wiley & Sons, Ltd.     

混流式水轮机转轮的刚强度分析

运用CFX软件对混流式转轮不同工况下的流场进行计算，得出作用在转轮上的压力。通过有限元软件把叶片的压力分布作为荷裁加载到转轮上．由此精确地计算变工况下的混流式转轮及叶片刚强度，确定出混流式转轮叶片上的应力和变形。