Study of Vehicle Exhaust Variation with Test Modes

Nowadays harmful gas in vehicle exhaust has pollute d air heavily. To prevent the environment from polluting, the request of emissions control legislation becomes more stringent. New legislation prescribes not only the emissions limitation of vehicles, but also testing instruments and methods. Test car must be operated on the chassis dynamometer and data must be collect ed and analyzed with prescriptive exhaust analysis system as well. The mass of harmful exhaust gas, containing the concentration and volume of emis sion, which is independent from the model of automobile and engine, can be used as a criterion to evaluate the pollution of an automobile. Constant Volume Sampl e System (CVS) is used to measure vehicle emissions, but it is too expensive to apply extensively. The Vehicle Mass Analysis System(Vmas), a new vehicle exhaust mass analysis system produced in USA late 1990s,is used to test and analyze veh icle exhaust. As a test instrument, it has the virtue of cheapness and easy mana geability. In this paper, Vmas is used to measure the emissions of a light truck CA1020F. A ccording to 15 running modes of Vehicle Exhaust Legislation, the test car is ope rated on the chassis dynamometer and data are collected and analyzed with Vmas. The test results show that it is viable to measure and evaluate automobile emiss ion with Vmas. Most of HC exhaust is produced when the car is decelerating. The major factor that influences the mass of HC emission is the sudden decrease of e ngine load causing incomplete combustion in decelerating mode. Test results indi cate CO and NOx are mainly produced in the process of increasing load. The forme r reason is incomplete combustion and the latter is high burning temperature cau sed by the increasing load. The methods of reducing automobile emission are also discussed in this paper.

Analysis of Incomplete Data of Accelerated Life Testing with Competing Failure Modes

Data obtained from accelerated life testing （ALT） when there are two or more failure modes, which is commonly referred to as competing failure modes, are often incomplete. The incompleteness is mainly due to censoring, as well as masking which might be the case that the failure time is observed, but its corresponding failure mode is not identified. Because the identification of the failure mode may be expensive, or very difficult to investigate due to lack of appropriate diagnostics. A method is proposed for analyzing incomplete data of constant stress ALT with competing failure modes. It is assumed that failure modes have s-independent latent lifetimes and the log lifetime of each failure mode can be written as a linear function of stress. The parameters of the model are estimated by using the expectation maximum （EM） algorithm with incomplete data. Simulation studies are performed to check＇model validity and investigate the properties of estimates. For further validation, the method is also illustrated by an example, which shows the process of analyze incomplete data from ALT of some insulation system. Because of considering the incompleteness of data in modeling and making use of the EM algorithm in estimating, the method becomes more flexible in ALT analysis.

Optimal selection of tests for fault detection and isolation in multi-operating mode system

The complex systems are often in the structure of multi-operating modes, and the components implementing system functions are different under different operation modes, which results in the problems that components often fail in different operating modes, faults can be only detected in specified operating modes, tests can be available in specified operating modes,and the cost and efficiency of detecting and isolating faults are different under different operating modes and isolation levels. Aiming at these problems, an optimal test selection method for fault detection and isolation in the multi-operating mode system is proposed by using the fault pair coding and rollout algorithm. Firstly,the faults in fault-test correlation matrices under different operating modes are combined to fault-pairs, which is used to construct the fault pair-test correlation matrices under different operating modes.Secondly, the final fault pair-test correlation matrix of the multioperating mode system is obtained by operating the fault pair-test correlation matrices under different operating modes. Based on the final fault pair-test correlation matrix, the necessary tests are selected by the rollout algorithm orderly. Finally, the effectiveness of the proposed method is verified by examples of the optimal test selection in the multi-operating mode system with faults isolated to different levels. The result shows that the proposed method can effectively mine the fault detection and isolation ability of tests and it is suitable for the optimal test selection of the multi-operating mode system with faults isolated to the replacement unit and specific fault.

Mode Innovation of School-Enterprise Cooperation on Food Safety Testing Laboratory Reform

In view of the difficulties about school-enterprise cooperation on food safety testing laboratory reform,the current training program,teaching methods and teaching forms are not suitable for the new platform.This paper provides new ideas and modes to solve these problems,such as integrating the resource elements between school and enterprise,establishing new platforms with the help of external force and innovating the cooperation modes to improve the laboratory,which can fully serve teaching,scientific research and enterprise production.

Shaking test research on connection modes between block infill wall and frame beam

In order to achieve an optimal anti-seismic behavior,or rather stability,the out-of-plane stability of infill wall in frame has been researched with the shaking test of four sets of two-layer infill wall,in which four different connection modes of filled with inclined bricks on the top,disconnection,flexibility and semi-flexibility were adapted.The acceleration and displacement response of the specimens were analyzed under the seismic load.Also,some feasible connection modes were gained by comparing the response of infill walls.Finally,the calculation of earthquake of infill wall was held.The results showed that seismic responses of the infill walls whose connect with frame in form of flexibility and semi-flexibility modes are weaker than others obviously,and their integrality is better.Thus the conclusion could be drawn that out-of-plane stability of the specimens with connection modes of flexibility and semi-flexibility are better than those with the connection modes of filled with inclined bricks on the top and disconnection.The research results can provide evidence for establishing specifications and directing the construction and therefore help reduce the casualties and property loss caused by earthquake disasters.

Centrifuge model tests of the formation mechanism of coarse sand debris flow

Using the self-developed visualization test apparatus, centrifuge model tests at 20 g were carried out to research the macro and microscopic formation mechanism of coarse sand debris flows. The formation mode and soil-water interaction mechanism of the debris flows were analyzed from both macroscopic and microscopic points of view respectively using high digital imaging equipment and micro-structure analysis software Geodip. The test results indicate that the forming process of debris flow mainly consists of three stages, namely the infiltration and softening stage, the overall slide stage, and debris flow stage. The essence of simulated coarse sand slope forming debris flow is that local fluidization cause slope to wholly slide. The movement of small particles forms a transient stagnant layer with increasing saturation, causing soil shear strength lost and local fluidization. When the driving force of the saturated soil exceeds the resisting force, debris flow happens on the coarse sand slope immediately.

Precipitation Forecast Test Based on MODE

Abstract By testing and analyzing BJ-RUC forecast of one precipitation process, MODE was introduced. MODE could give objective comparison from position of precipitation falling zone, shape and direction, and reflect intensity difference between forecast and actual situation, which comprehensively reflected precipitation forecast performance of the model, and was close to subjective judgment thinking of forecaster.

Architecture and Methodology of Unit Testing Embedding Pair-Wise Mode for Small Team

In this paper, the new organization for unit testing embedding pair-wise mode is proposed with the core thought focused on the cooperation of programmer and tester by “cross-testing”. The typical content of unit testing for the new organizing mode should have three aspects, including self-checking, cross-testing and independent-testing. For cross-testing, executing “pair-wise” mode, mainly tackles data testing, function testing and state testing, which function testing must be done by details and state testing must be considered for completeness. With the specializing of independent-testing, it should be taken as more rigid testing without arbitrariness. Consequently, strategy and measure are addressed for data testing focusing on boundary testing and function/state testing. And organizing method of procedure and key points of tackling unit testing are investigated for the new organizing mode. In order to assess the validity of our study and approach, a series of actual examples are demonstrated for GUI software. The result indicates that the execution of unit testing for the new organizing mode is effective and applicable.

Current Mode Logic Testing of XOR/XNOR Circuit: A Case Study

This paper investigates the issue of testing Current Mode Logic (CML) gates. A three-bit parity checker is used as a case study. It is first shown that, as expected, the stuck-at fault model is not appropriate for testing CML gates. It is then proved that switching the order in which inputs are applied to a gate will affect the minimum test set;this is not the case in conventional voltage mode gates. Both the circuit output and its inverse have to be monitored to reduce the size of the test set.

聚丙烯纤维增强橡胶砂固结不排水剪切试验

鉴于橡胶砂作为回填材料时承载力低和变形量大的问题,采用加入聚丙烯纤维(PPF)的方法提高橡胶砂的力学性能,提出了聚丙烯纤维增强橡胶砂的半干拌式制备方法,通过48组聚丙烯纤维增强橡胶砂、普通橡胶砂和纯砂试样的固结不排水剪切试验,探究了聚丙烯纤维掺量和橡胶掺量等参数对聚丙烯纤维增强橡胶砂主要力学变形特征参数的影响.结果表明:聚丙烯纤维对橡胶砂弹性模量的影响较小;聚丙烯纤维增强橡胶砂具有先剪缩后剪胀破坏的特征,其偏应力与轴向应变关系为应变硬化型;聚丙烯纤维可有效提高橡胶砂的内摩擦角和黏聚力;聚丙烯纤维增强橡胶砂破坏偏应力的提升效果十分显著,最高可提高3倍.

Research on the Equivalence Between Double Differential- mode Current Injection and Radiation Test Method

There are the application scope limits for single differential-mode current injection test method, so in order to carry out injection susceptibility test for two-pieces equipment interconnected with both ends of a cable simultaneously, a double differential-mode current in- jection test method (DDMCI) is proposed. The method adopted the equivalence source wave theorem and Baum-Liu-Tesche(BLT) equation as its theory foundation. The equivalent corresponding relation between injection voltage and radiation electric field intensity is derived, and the phase relation between the two injection voltage sources is confirmed. The results indicate that the amplitude and phase of the equivalent injection voltage source is closely related to the S parameter of directional coupling device, the transmission line length, and the source vector in BLT equation, but has nothing to do with the reflection coefficient between the two equipment pieces. Therefore, by choosing the right amplitude and phase of the double injection voltage sources, the DDMCI test is equivalent to the radiation test for two interconnected equipment of a system.

预制拼装铁路重力式桥墩的抗震性能研究

为适应中国铁路建设向高烈度震区快速发展的需要,解决传统预制拼装桥墩墩柱及承台连接位置薄弱等问题,提出一种灌浆波纹管连接的模块化预制拼装桥墩体系,通过设置承台与墩身塑性区域共同浇筑及墩底局部无黏结段增强桥墩的抗震性能。制作1个局部无黏结整体现浇铁路重力式桥墩模型和1个局部无黏结预制拼装铁路重力式桥墩模型开展拟静力试验,并结合有限元分析,进行预制拼装铁路重力式桥墩抗震性能研究。结果表明:局部无黏结预制拼装桥墩整体连接性能稳定,可通过墩底塑性区域破坏与墩身及节段间的摇摆实现共同消能,其破坏模式表现为墩底塑性区域的弯曲破坏,未发生破坏位置转移现象;局部无黏结预制拼装桥墩等效塑性区域高度比整体现浇桥墩降低,抗侧向水平承载力与耗能能力提升显著,位移延性能力良好,可适应更大加载位移,最终累积耗能增长64.3%;结构接缝位置连接稳定可靠,同等加载位移下等效刚度基本一致,抗震性能得到明显提高;预制节段划分对预制拼装铁路重力式桥墩抗震性能的影响不大。

绕墙底转动模式下装配式挡土墙土压力研究

墙背土压力分布及大小是装配式挡土墙设计的关键依据。设计并开展新型装配式混凝土挡土墙现场试验,研究挡土墙在加载条件下的位移模式和土压力分布规律。以现场试验为原型,建立无黏性填土、墙背倾斜且粗糙的挡土墙理论计算模型,同时考虑挡土墙位移模式与大小、土拱效应和土层间剪应力的影响,采用水平层分析法推导了绕墙底转动(RB)模式下挡土墙的土压力计算公式。结果表明:①该装配式挡土墙整体性能良好,绕墙底刚性转动。在RB模式下,墙顶处土体最先达到主动极限状态,土体从上至下逐渐达到极限状态;任意深度处的土体位移S_(c)达到7 mm时将达到极限状态,即S_(c)=0.16%H(H为墙高)。②本文理论解与试验值吻合较好,计算公式可用于求解挡土墙绕墙底转动过程中的土压力分布及大小。③随着挡土墙转动幅度的增大,土压力分布曲线凹向逐渐明显,土压力合力作用点高度呈现先降低后回升的现象;挡土墙转动角度η=0.007 rad为挡土墙达到主动状态的临界值。

钢支撑-钢筋混凝土掉层框架结构抗震性能试验研究

为改善坡地钢筋混凝土(RC)掉层框架结构抗侧刚度分布的不均匀性,设计了一栋在上接地层设置钢支撑的RC掉层框架结构,按1/4比例提取其顺坡向中榀框架下部5层子结构为试验对象,开展钢支撑-RC掉层框架拟静力试验,观测试件的破坏过程,并对比RC掉层框架试验所得试件的破坏形态,分析试件滞回性能、延性和刚度退化等抗震性能指标。结果表明:试件的最终破坏是以第4层柱底混凝土压溃,梁端混凝土剥落、底部钢筋断裂,顶层柱顶混凝土剥落为标志。与RC掉层框架试验结果相比,钢支撑-RC掉层框架试件上接地柱的破坏明显减轻,柱端破坏分布也更为均匀,避免了掉层框架结构“半层破坏模式”的出现,改善了结构的耗能和抗地震倒塌能力。但试件上接地层相邻上一层的变形和破坏程度较大,应对该楼层的柱端进行适当的抗震加强;设置钢支撑后,试件的滞回曲线较为饱满,并具有良好的延性(正、负向加载的位移延性系数分别可达5.13、5.69),正负向加载的刚度退化曲线也趋于对称。

临床生化检验学混合教学模式的构建及应用

教学团队依托中国大学MOOC平台,搭建了临床生化检验学在线课程。在此基础上,构建了“在线课程学习-临床案例收集-PBL研讨-课后健康教育”的线上线下混合式教学模式。在这个过程中,解决了教与学过程中存在的4个脱节,实现了3个层次的整合,最终目的是培养医学生自主学习和终身学习的能力。

基于有限元分析的连续油管寿命研究及预测模型

目前针对连续油管的寿命预测研究较少,但在实际的生产中连续油管的突然失效会造成极大安全隐患,急需解决方案。针对此问题,本文使用有限元仿真方法,针对三种规格的CT80连续油管在不同工况下进行有限元分析,得到了连续油管的受力、形变和疲劳寿命。用疲劳试验对有限元分析进行验证,证明了有限元分析的疲劳寿命的准确性。将连续油管的直径、壁厚、内压、弯曲半径参数转化为外壁应变和环向应力,通过数据拟合建立了关于外壁应变、环向应力和疲劳寿命之间的全经验公式,得到连续油管疲劳寿命预测模型。并用试验得出的结果与疲劳寿命预测模型进行比较,误差较小,可用于CT80连续油管的疲劳寿命预测,最后通过疲劳试验得到了连续油管在二级加载下的疲劳寿命模型,该模型可预测油管在第二级载荷下的剩余疲劳寿命。

Q460高强钢管柱-H形梁焊接节点循环拉伸性能试验研究

为研究Q460高强钢管柱-H形梁焊接节点在地震作用下的力学行为,对11个梁翼缘板与柱段焊接组成的节点进行了低周循环拉伸性能试验,研究了梁翼缘板与钢管宽度比α、厚度比β以及钢管宽厚比λ等参数对节点破坏模式、承载力、延性和耗能能力的影响规律。结果表明:在循环拉伸荷载作用下,Q460高强钢管柱-H形梁焊接节点的失效模式主要分为连接处焊缝断裂、连接处钢管面板断裂或梁翼缘板被拉断三种;高强钢梁翼缘板与钢管宽度比、钢管柱宽厚比对焊接节点的受力行为影响较大,当宽厚比α由25.0减小到18.75时,节点的应变能减小了134%;当节点破坏时,具有新型焊接通过孔构造的焊接节点极限位移超过传统构造节点近2倍,前者延性性能较好。研究成果可为高强钢管柱与梁焊接节点的抗震设计以及进一步的理论研究提供依据。

不同钢纤维掺量全轻混凝土梁落锤冲击试验研究

由于全轻混凝土结构抗剪承载力较低,因此有必要探究钢纤维的加入对全轻混凝土梁动力性能的影响。设计钢纤维体积掺量为0%、1%、2%共3根适筋梁,对其跨中区域进行落锤冲击试验,并利用LS-dyna有限元软件进行数值模拟,对比分析各试件破坏形态、冲击力时程曲线、跨中位移时程曲线。试验结果表明:在相同冲击荷载作用下随着钢纤维体积掺量的增加抑制裂缝产生和发展的现象越显著,并且裂缝相对更加集中于梁跨中区域,支座处裂缝相对减少。钢纤维的加入不影响试件冲击力最大值,但随着钢纤维体积掺量的增加,各试件冲击力第二峰值与最大值之比增加14%和26%,跨中位移最大值与残余位移分别降低3、8mm与3、7mm。经研究得出钢纤维的加入显著提高全轻混凝土梁抗冲击性能。

联肢弯剪型钢板剪力墙抗震性能试验研究

联肢钢板剪力墙结构是将2片钢板剪力墙通过钢连梁连接形成的抗侧力结构。通过对1榀1/3缩尺的4层联肢弯剪型钢板剪力墙试件进行低周往复加载试验,从滞回曲线、骨架曲线、延性、承载力及刚度退化、耗能能力等方面研究了该结构体系的抗震性能,并且对试件的屈服顺序和变形模式进行了分析。结果表明:联肢钢板剪力墙试件的延性系数达到5.03,承载力退化系数均大于0.96,承载力和刚度退化稳定,等效黏滞阻尼系数达到0.25以上,表明联肢弯剪型钢板剪力墙具有优越的抗震性能。加载过程中,连梁先于墙板发生屈服,墙板先屈曲后屈服,此后柱脚和横梁相继屈服。连梁的引入改变了结构的屈服机制,提高了整体的延性和耗能能力,能够组成多道抗震防线,且试件整体最终也体现出合理的破坏机制。整体侧移曲线呈弯剪变形模式。该试验研究更加贴合实际工程中联肢钢板剪力墙结构的应用情况,为联肢钢板剪力墙结构的进一步研究和应用提供了试验基础。

开口断面钢-混结合梁悬索桥颤振特性及颤振形态研究

为准确评估开口断面双边箱钢-混结合梁悬索桥颤振性能和多模态参与效应,以典型的钢-混结合梁悬索桥——怀化洞庭溪沅水特大桥为背景,开展风洞模型试验及数值分析。制作加劲梁节段缩尺模型并进行风洞试验,测试原桥梁结构的颤振性能,分析调整阻尼比、采用气动措施及结构措施对结构颤振特性的影响,采用三维和二维两种颤振分析方法分析设置中央扣结构的颤振模态及多模态参与效应。结果表明:该钢-混结合梁悬索桥存在较明显的颤振起振点,且颤振是以扭转为主的弯扭耦合振动,同时其扭转和竖向振动存在较大的相位差(相差近180°);节段模型风洞试验与三维和二维颤振分析一致得到设置中央扣后,频率较高的正对称扭转模态先于反对称模态发生颤振,且三维与二维颤振分析结果相差不大。