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831.
The BCH formula of Rezek and Kosloff (2006) [10] is a convenient tool to handle a family of density matrices, which occurs in the study of quantum heat engines. We prove the formula using a known argument from Lie theory. 相似文献
832.
A study on the effect of electronic engine speed regulator on agricultural tractor ride vibration behavior 总被引:1,自引:0,他引:1
In this study, the effect of electronic speed adjustment on tractor ride vibration levels is examined. With normal pedal operation the engine rotational speed drops with an increasing load. The electronic regulator provides a constant speed mode of operation independent of the load. Vibration levels were measured under different operating conditions and surfaces. As a first series of tests, the tractor was driven on a conglomerate bituminous track at speeds of 20, 25 and 28 km/h. Vibration was measured upon the surface of the operator seat simultaneously in the x, y and z directions. The reference axis system was that defined by the ISO 2631-1 [1]. The weighted r.m.s. acceleration was found to be between 8% and 8.6% higher for the case where operation with electronic speed adjustment had been selected. Secondly, cultivating was chosen as the field task and the vibration was measured while the tractor was traversing a rough farm track at speeds of 6, 7.5 and 9 km/h. In this case, the vibration levels with automatic speed adjustment were between 4.3% and 8.6% lower than when driving with normal foot pedal operation. From the above results, we may infer that electronic speed regulation should not be used in transportation on asphalt country roads. On the contrary, it seems that electronic regulation has an advantage when used in typical field tasks such as cultivating. 相似文献
833.
An on-engine method for dynamic characterisation of automotive NOx concentration sensors is presented. Steps in start of injection on a diesel engine are employed to achieve step-like NOx concentration variations on exhaust flow. On the basis of the sensor response, delay and dynamic response can be easily identified; the paper shows a simple least squares procedure although other models and identification techniques could be used. Application data is presented for three NOx sensors: a research-grade chemiluminescence exhaust gas analyser, and two different commercial ZrO2-based sensors. 相似文献
834.
835.
836.
热声发动机的起振过程是一个产生并维持自激振荡的过程, 研究热声自激振荡机理有助于进一步了解热声效应的实质. 根据热声网络理论, 建立了驻波热声发动机的整机网络. 将热声网络比拟成电网络, 利用厄米特式计算了输入热声网络的视在功流, 功流平衡对应自激, 在角频率虚部为零的情况下计算了热声发动机的阈值温度和运行频率. 结果表明, 计算值与实验值符合得较好, 充气压力与阈值温度和运行频率的耦合关系大致相同. 所得结论有助于进一步探究热声效应机理以及热声发动机系统的优化设计. 相似文献
837.
随着飞机功能和性能要求的不断提高,其综合化程度、复杂性也越来越高,传统的故障诊断方法已经不能满足日益复杂的飞机维护需求。针对传统诊断方法对系统的强依赖性和在多故障模式下处理能力不足等问题,给出一种基于多信号模型的故障诊断方法,设计并实现了基于多信号模型的诊断推理机,并用以某型飞机的自动飞行控制系统为对象验证了该方法在解决飞机系统故障关联和多故障诊断问题中的有效性。 相似文献
838.
Elaheh Neshat Rahim Khoshbakhti Saray 《Mathematical and Computer Modelling of Dynamical Systems: Methods, Tools and Applications in Engineering and Related Sciences》2019,25(2):167-194
The main purpose of the current study is mathematical modelling and validation of mass transfer phenomenon in homogeneous charge compression ignition engines. A validated multi-zone model coupled to a semi-detailed chemical kinetics is used to predict homogeneous charge compression ignition combustion and emissions. Heat and Mass transfer submodels are linked to the multi-zone model. Bulk flow and diffusion mass transfer between zones are considered. The results indicate that the diffusion mass transfer is negligible in homogeneous charge compression ignition engines. Bulk flow mass transfer plays a critical role in homogeneous charge compression ignition simulation and applying it in the multi-zone model leads to accurate prediction of the start of combustion, peak pressure and exhaust emissions. The results show that the maximum error changes from 90% to 5% in carbon monoxide prediction and from 98% to 14% in unburned hydrocarbons prediction, using the mass transfer submodel. 相似文献
839.
AlO孔结构对纳米HZSM基催化剂改质FCC汽油性能的影响 《燃料化学学报》2013,41(11):1343-1348
采用NH3-TPD、FT-IR、N2吸附-脱附等手段对两种不同来源的氧化铝样品进行了表征。结果表明,两种Al2O3的总酸量及酸强度没有明显差别,酸类型均以Lewis酸为主,其中,Al2O3 (b)的平均孔径及孔体积较大。在固定床微型反应装置上考察了以两种Al2O3为载体制备的纳米HZSM-5基催化剂改质全馏分FCC汽油的性能。实验结果表明,以大孔Al2O3为载体的HZSM-5基催化剂具有较好的降烯烃、芳构化、异构化活性及稳定性。改性纳米HZSM-5负载的LaNiMo催化剂对FCC汽油的300 h评价结果表明,烯烃饱和率为83%,脱硫率为87%,同时维持了油品的辛烷值。 相似文献
840.
O. D. Adeniyi A. S. Kovo A. S. Abdulkareem C. Chukwudozie 《Journal of Dispersion Science and Technology》2013,34(4):501-504
The potential in alcohols as fuel had for long being recognized by the early inventors of machines and engines, even before gasoline and the hydrocarbons became popular. In fact, Henry Ford, one of the pioneers in automobile manufacture, designed his equipment to run on ethanol. But since then, time has seen gasoline and other conventional fuels take the front seat in engine application. This article is an insight into the experiment carried out to produce fuel from cassava starch and the characterization to determine some of the fuel properties in comparison to gasoline. The choice of cassava for the production was based on its availability and ability to grow in almost all geographical regions in Nigeria. Experimental production gave a sample concentration of 87% corresponding to a yield of 0.534 cm3 of ethanol per gram of starch hydrolyzed while the sample characteristics for the latent heat of vaporization, heat of combustion, flash point, and density are 950 kJ/kg, 22133.7 kJ/kg, 17–20°C, and 0.825, respectively. The results obtained compared favorably with those of gasoline that the sample concentration. 相似文献