大骨节病病因研究——病区天堂村饮水中有机物的测定(Ⅰ)

本研究应用XAD树脂富集,色谱/质谱联机分离鉴定的方法。对大骨节病病区(麟游县天堂村)三种饮水与对照(西安医科大学校园)深井水作了痕量有机化合物的测定分析。从天堂河水、深机井水、窑水与对照水样中分别检出了40种、31种、19种和10种有机化合物,且对每种检出物的结构式、分子量和峰面积均作了分析测定。其中芳核化合物分别为25种、19种、8种和4种。病区三种水样中均检出了烯类、烯酮类、酮类和萘类、苯并噻唑等稠环芳烃化合物;仅在河水和深井水样中检出了茚类化合物;在对照水样中未发现上述有机物。此结果未见文献报导。上述诸有机化合物可能是值得重视的可疑病因因素,但其真正的病因流行病学意义尚需进一步研究探讨。     

Gas anxiety and the charging choices of plug-in hybrid electric vehicle drivers

Plug-in hybrid electric vehicles (PHEVs) can provide many of the benefits of battery electric vehicles (BEVs), such as reduced petroleum consumption and greenhouse gas emissions, without the “range anxiety” that can accompany driving a vehicle with limited range when there are few charging opportunities. However, evidence indicates that PHEVs are often plugged in more frequently than BEVs in practice. This is somewhat paradoxical: drivers for whom plugging in is optional tend to do so more frequently than those for whom it is necessary. This has led to the coining of a new term – “gas anxiety” – to describe the apparent desire of PHEV drivers to avoid using gasoline. In this paper, we analyze the variables influencing the charging choices of PHEV owners, testing whether drivers express preferences consistent with the concept of gas anxiety. We analyze data collected in a web-based stated preference survey using a latent class logit model. The results reveal two classes of decision-making patterns among the survey respondents: (1) those who weight the cost of gasoline and the cost of recharging approximately equally (the cost-minimizing class), and (2) those who weight the cost gasoline more heavily than the cost of recharging (the gas anxiety class). Respondents in the gas anxiety class expressed a willingness to recharge at a charging station even when doing so would cost approximately four times as much as the cost of the gasoline avoided. While the gas anxiety class represents the majority of our sample, more recent PHEV adopters are more likely to be in the cost-minimizing class. Looking forward, this suggests that public charging station operators may need to price charging competitively with gasoline on a per-mile basis to attract PHEV owners.     

燃气轮机性能的数学模型及其优化解法

本文建立了流量残量方程组形式的燃气轮机性能的新数学模型，并提出了用Newton-Raphson和DFP－BFS优化组合解法来求解该模型。计算实践表明，该法不仅稳定性高、收敛速度快，而且求解精度高，可在任何工况下都得到较为满意的结果，在燃气轮机设计中有一定的实用价值。     

压缩过程喷水蒸发内冷燃气轮机循环分析

本文研究了燃气轮机压缩过程喷水直接掺混蒸发内冷回热的必要性，以及喷水量对压缩过程耗功、燃机输出有效功与效率的影响。通过循环计算得出压缩过程喷水蒸发内冷燃气轮机的一些重要的结论并提出级间喷水的设想及其可行性。     

改进的双工质平行复合循环燃气轮机循环分析

分析了改进的双工质平行复合循环燃气轮机装置性能特点，给出模型和一些计算结果。与改进前的装置效率、比功比较，该装置部套少，成本低，易于利用传统的燃气轮机改装，具有良好的发展前景。     

进气冷却式回热燃气轮机循环数值模拟和分析

针对简单循环燃气轮机性能偏低且易受大气温度变化的影响，本文提出了一种由吸收制机徊汽轮机组成的新型循环－－进气冷却式回热式燃气机循环，对其建模进行数值模拟和分析。结果表明，此循环既能较大幅度提高燃气轮机装置的性能，又能有效地改善燃气轮机性能对大气温度变化的敏感性。     

船用燃机性能降级新型预测模型建立及应用分析

船用燃气轮机气路维护是舰船动力系统健康管理当中必要的环节,采用视情维护的方法是当前十分先进的维护手段,其中对气路降级趋势的预测是维护方法的核心。气路降级数据具有明确的增长趋势与不规律的波动性,符合灰色系统的特征。本文采用无偏灰色预测模型改进灰色马尔科夫模型,在此基础上扩大原始数据的维数,采用灰色关联度模型,将类似于当前序列的参考序列引入,最终构成了一种新的混合预测模型。最后,选择燃气轮机压气机结垢的过程作为实例来验证这一新的模型。通过研究模型参数和预测准确性之间的关系,为实例提出了建议的最佳参数。从预测准确性与对波动性的预测角度与不同的预测模型的比较结果表明,新的模型优于一些其他序列预测模型。     

Effect of intake valve swirl on fuel-gas mixing and subsequent combustion in a CAI engine

A fully three-dimensional model was used to investigate the optimal value for intake valve lift in a CAI engine. Uniform mixing in the engine is a key parameter that affects the auto-ignition reliability and thermal efficiency. The method of intake of the air supply often determines the uniformity (or quality) of the fuel-air mixture. In this paper, four strategies were applied for controlling the swirl intensity of intake air. The variation of the intake valve lift induces different swirling and tumbling intensities. Both experimental data and 1D WAVE software (Ricardo, Co.) were coupled with the 3D model to provide pressure and temperature boundary conditions. The initial condition of the EGR mass fraction was also provided by the 1D model. The benchmark scenario (Case 1) was considered as a valve lift with 2 mm for all intake valves. We found that an intake valve lift of 6 mm with the other intake valve closed (i.e., Case 5) yielded the largest swirling (helical motion in the axial direction) and tumbling, which in turn rendered optimal fuel-gas mixing. We also found that fuel distribution affected the auto-ignition sites (or spot). The better the mixing, the greater the gas temperature and combustion efficiency achieved, as seen in Case 5. The NOx level, however, was increased due to the gas temperature. The optimal operating condition is selected from the viewpoints of environmental protection and combustion efficiency.     

丰田凯美瑞发动机点火系统原理与故障排除实例

针对广州丰田凯美瑞轿车一例特殊故障——发动机高速运行之后抖动、动力下降,着重分析其发动机点火系统的工作原理,并对故障现象作逐步的诊断和分析,最终排除故障。     

浅析LNG在商用车中的应用

论文对LNG在商用车中的应用进行了分析研究,对LNG汽车的市场前景进行简要分析,并从LNG燃料的优点、LNG汽车供气系统技术方案、动力性研究以及其经济性四个方面进行了具体的阐述。研究表明LNG作为后起之秀,具有无与伦比的优势,发展前景看好。