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 th...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.展开更多
Ⅰ The Indexes of Detecting Oil and Gas Resources The deeply buried reservoir which in a dynamic equilibrium state has a great pressure inside, and between it and earth surface there is a great difference of pressure....Ⅰ The Indexes of Detecting Oil and Gas Resources The deeply buried reservoir which in a dynamic equilibrium state has a great pressure inside, and between it and earth surface there is a great difference of pressure. Therefore the hydrocarbon must spread and move vertically to the surface along the pressure gradient orientation. Hydrocarbons in the reservoir along some small rifts, cracks, joints and cleavages penetrate the overlying strata and seepage onto the surface. Thus the hydrocarbons become unvisble oil and gas signs. This process is called the phenomena of hydrocarbon microseepage of reservoir. Hydrocarbons microseepage in the process展开更多
In 1979, the Changchun Jingyuetan Remote Sensing Study and Test Site (RSSTS)began its work, and it was formally established in 1985. The RSSTS is subordinated the Changchun Branch of Chinese Academy of Sciences and is...In 1979, the Changchun Jingyuetan Remote Sensing Study and Test Site (RSSTS)began its work, and it was formally established in 1985. The RSSTS is subordinated the Changchun Branch of Chinese Academy of Sciences and is supported by the Changchun Institute of Geography and Changchun Institute of Optics and Fine Machnics, Chinese Academy of Sciences. It is under the management of the Resource & Environment Bureau of Chinese Academy of Sciences and it is the study base of remote sensing basis and application tests in China. The RSSTS is situated in the Jingyuetan scenic spot of the suburbs of Changchun City, Jilin Province. It is located at 43°40′—43°50′N and 125°18′-125°18′E.展开更多
目的探讨维持性血液透析(maintenance hemodialysis,MHD)患者计时站立行走测试(time up and go test,TUG)时间延长的影响因素。方法采用横断面调查法,选取2023年6月1日至2024年1月31日于首都医科大学附属北京潞河医院规律血液透析、数...目的探讨维持性血液透析(maintenance hemodialysis,MHD)患者计时站立行走测试(time up and go test,TUG)时间延长的影响因素。方法采用横断面调查法,选取2023年6月1日至2024年1月31日于首都医科大学附属北京潞河医院规律血液透析、数据完整且可配合的患者,分别采用简易精神状态检查表(Minimum Mental State Examination,MMSE)、5次起坐试验(5 times sit to stand,STS-5)、TUG量表评估患者认知功能、下肢肌肉力量、平衡及步态功能;根据TUG结果进行分组,即TUG≤12 s,判定为TUG正常组;TUG>12 s判定为TUG延长组,采用多因素Logistic回归法分析患者TUG延长组的影响因素,以受试者工作特征(receiver operating characteristic,ROC)曲线分析影响因素对TUG延长患者的预测价值。结果本研究共纳入146例MHD患者,TUG延长组86例,TUG正常组60例,两组的性别、年龄、合并高血压、合并糖尿病、血糖、教育水平、MMSE评分、C反应蛋白、血白蛋白、血肌酐、血钠、全段甲状旁腺素、低密度脂蛋白胆固醇、血尿酸、STS-5、单次尿素氮清除指数(urea clearance index,Kt/V)差异具有统计学意义(P<0.05);进一步行多因素Logistic回归分析显示,高龄、女性、低MMSE评分、低Kt/V以及STS-5时间延长是发生TUG延长的独立危险因素(P<0.05);ROC曲线显示,年龄、性别、MMSE总分、STS-5时间预测MHD患者发生TUG延长的曲线下面积(area under the curve,AUC)分别为0.825、0.678、0.777、0.836(P<0.01),具有较高的预测价值,Kt/V预测患者发生TUG延长的AUC为0.602(P=0.037),有一定的预测价值;以上5项指标作为整体模型预测MHD患者发生TUG延长的AUC为0.923(P<0.01)结论MHD患者的年龄、性别、MMSE评分、STS-5时间延长、Kt/V的水平与合并TUG延长相关,是发生TUG延长的独立危险因素,可能成为预测TUG延长的生物学指标。展开更多
近年来,国际上不同国家和地区有关风荷载计算的规范均有不同程度的更新迭代,为了研究规范中风荷载及风致加速度计算参数的差异影响,以联邦航空咨询委员会(Commonwealth Advisory Aeronautical Research Council,CAARC)提出的简单标准模...近年来,国际上不同国家和地区有关风荷载计算的规范均有不同程度的更新迭代,为了研究规范中风荷载及风致加速度计算参数的差异影响,以联邦航空咨询委员会(Commonwealth Advisory Aeronautical Research Council,CAARC)提出的简单标准模型试验为例,对不同国家和地区的矩形高层建筑顺风向风荷载及风致加速度进行对比研究。首先,对不同规范给定的风场特性及风场参数进行了详细分析;随后,将不同规范中的风荷载和风致加速度计算公式归一化处理;最后,结合风洞试验结果,详细讨论参考风速、湍流强度、湍流积分尺度、峰值因子、背景响应因子、共振响应因子、阵风响应因子的差异及其对风荷载及风致加速度的影响。结果表明:风场参数的差异是造成高层建筑顺风向风荷载和风致加速度不同的决定性因素。展开更多
In developing and using measures of Language abilities, the most important consideration is the use of a language test, so that the most important quality of a test is its usefulness. A model of test usefulness is reg...In developing and using measures of Language abilities, the most important consideration is the use of a language test, so that the most important quality of a test is its usefulness. A model of test usefulness is regarded as the essential basis for quality control throughout the entire test development process. A model of test usefulness includes following qualities--validity, reliability, discrimination and backwash effects.展开更多
目的探究稳定期精神分裂症患者的注意力特点。方法纳入55例稳定期精神分裂症患者和55名健康对照。采用注意网络测试范式(attention network test paradigm,ANT)对被试的注意力进行测评,观察指标包括4种提示线索和3种刺激类型下的反应时...目的探究稳定期精神分裂症患者的注意力特点。方法纳入55例稳定期精神分裂症患者和55名健康对照。采用注意网络测试范式(attention network test paradigm,ANT)对被试的注意力进行测评,观察指标包括4种提示线索和3种刺激类型下的反应时,以及换算后的3种注意网络(警觉网络、定向网络和执行控制网络)反应时。结果在不同提示线索和刺激类型下,患者组的反应时均高于对照组(P<0.001)。患者组的警觉网络反应时[25.43(11.71,42.53)ms vs.39.32(27.46,51.98)ms,P=0.020]和执行控制网络反应时[96.17(36.32,160.13)ms vs.44.43(18.52,89.73)ms,P<0.001]低于对照组,定向网络反应时在两组之间的差异无统计学意义(P=0.136)。结论稳定期精神分裂症患者的警觉网络和执行控制网络存在明显损伤,而定向网络未见明显损伤。展开更多
文摘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.
文摘Ⅰ The Indexes of Detecting Oil and Gas Resources The deeply buried reservoir which in a dynamic equilibrium state has a great pressure inside, and between it and earth surface there is a great difference of pressure. Therefore the hydrocarbon must spread and move vertically to the surface along the pressure gradient orientation. Hydrocarbons in the reservoir along some small rifts, cracks, joints and cleavages penetrate the overlying strata and seepage onto the surface. Thus the hydrocarbons become unvisble oil and gas signs. This process is called the phenomena of hydrocarbon microseepage of reservoir. Hydrocarbons microseepage in the process
文摘In 1979, the Changchun Jingyuetan Remote Sensing Study and Test Site (RSSTS)began its work, and it was formally established in 1985. The RSSTS is subordinated the Changchun Branch of Chinese Academy of Sciences and is supported by the Changchun Institute of Geography and Changchun Institute of Optics and Fine Machnics, Chinese Academy of Sciences. It is under the management of the Resource & Environment Bureau of Chinese Academy of Sciences and it is the study base of remote sensing basis and application tests in China. The RSSTS is situated in the Jingyuetan scenic spot of the suburbs of Changchun City, Jilin Province. It is located at 43°40′—43°50′N and 125°18′-125°18′E.
文摘目的探讨维持性血液透析(maintenance hemodialysis,MHD)患者计时站立行走测试(time up and go test,TUG)时间延长的影响因素。方法采用横断面调查法,选取2023年6月1日至2024年1月31日于首都医科大学附属北京潞河医院规律血液透析、数据完整且可配合的患者,分别采用简易精神状态检查表(Minimum Mental State Examination,MMSE)、5次起坐试验(5 times sit to stand,STS-5)、TUG量表评估患者认知功能、下肢肌肉力量、平衡及步态功能;根据TUG结果进行分组,即TUG≤12 s,判定为TUG正常组;TUG>12 s判定为TUG延长组,采用多因素Logistic回归法分析患者TUG延长组的影响因素,以受试者工作特征(receiver operating characteristic,ROC)曲线分析影响因素对TUG延长患者的预测价值。结果本研究共纳入146例MHD患者,TUG延长组86例,TUG正常组60例,两组的性别、年龄、合并高血压、合并糖尿病、血糖、教育水平、MMSE评分、C反应蛋白、血白蛋白、血肌酐、血钠、全段甲状旁腺素、低密度脂蛋白胆固醇、血尿酸、STS-5、单次尿素氮清除指数(urea clearance index,Kt/V)差异具有统计学意义(P<0.05);进一步行多因素Logistic回归分析显示,高龄、女性、低MMSE评分、低Kt/V以及STS-5时间延长是发生TUG延长的独立危险因素(P<0.05);ROC曲线显示,年龄、性别、MMSE总分、STS-5时间预测MHD患者发生TUG延长的曲线下面积(area under the curve,AUC)分别为0.825、0.678、0.777、0.836(P<0.01),具有较高的预测价值,Kt/V预测患者发生TUG延长的AUC为0.602(P=0.037),有一定的预测价值;以上5项指标作为整体模型预测MHD患者发生TUG延长的AUC为0.923(P<0.01)结论MHD患者的年龄、性别、MMSE评分、STS-5时间延长、Kt/V的水平与合并TUG延长相关,是发生TUG延长的独立危险因素,可能成为预测TUG延长的生物学指标。
文摘近年来,国际上不同国家和地区有关风荷载计算的规范均有不同程度的更新迭代,为了研究规范中风荷载及风致加速度计算参数的差异影响,以联邦航空咨询委员会(Commonwealth Advisory Aeronautical Research Council,CAARC)提出的简单标准模型试验为例,对不同国家和地区的矩形高层建筑顺风向风荷载及风致加速度进行对比研究。首先,对不同规范给定的风场特性及风场参数进行了详细分析;随后,将不同规范中的风荷载和风致加速度计算公式归一化处理;最后,结合风洞试验结果,详细讨论参考风速、湍流强度、湍流积分尺度、峰值因子、背景响应因子、共振响应因子、阵风响应因子的差异及其对风荷载及风致加速度的影响。结果表明:风场参数的差异是造成高层建筑顺风向风荷载和风致加速度不同的决定性因素。
文摘In developing and using measures of Language abilities, the most important consideration is the use of a language test, so that the most important quality of a test is its usefulness. A model of test usefulness is regarded as the essential basis for quality control throughout the entire test development process. A model of test usefulness includes following qualities--validity, reliability, discrimination and backwash effects.
