Measurement of in-vehicle volatile organic compounds under static conditions

The types and quantities of volatile organic compounds （VOCs） inside vehicles have been determined in one new vehicle and two old vehicles under static conditions using the Thermodesorber-Gas Chromatograph/Mass Spectrometer （TD-GC/MS）. Air sampling and analysis was conducted under the requirement of USEPA Method TO-17. A room-size, environment test chamber was utilized to provide stable and accurate control of the required environmental conditions （temperature, humidity, horizontal and vertical airflow velocity, and background VOCs concentration）. Static vehicle testing demonstrated that although the amount of total volatile organic compounds （TVOC） detected within each vehicle was relatively distinct （4940 μg/m^3 in the new vehicle A, 1240 μg/m^3 in used vehicle B, and 132 μg/m^3 in used vehicle C）, toluene, xylene, some aromatic compounds, and various C7-C12 alkanes were among the predominant VOC species in all three vehicles tested. In addition, tetramethyl succinonitrile, possibly derived from foam cushions was detected in vehicle B. The types and quantities of VOCs varied considerably according to various kinds of factors, such as, vehicle age, vehicle model, temperature, air exchange rate, and environment airflow velocity. For example, if the airflow velocity increases from 0.1 m/s to 0.7 m/s, the vehicle＇s air exchange rate increases from 0.15 h^-1 to 0.67 h^-1, and in-vehicle TVOC concentration decreases from 1780 to 1201 μg/m^3.

THE DERIVATION OF EXACT STATIC CONDITIONS AT THE CORNER POINTS FOR THE BENDING OF THICK RECTANGULAR PLATES

In this paper, exact static conditions at the corner points for the bending of thickrectangular ptates are strictly. derived from the theorem of minimum potentialenerg[1].

Improved Prediction of Slope Stability under Static and Dynamic Conditions Using Tree-BasedModels

Slope stability prediction plays a significant role in landslide disaster prevention and mitigation.This paper’s reduced error pruning(REP)tree and random tree(RT)models are developed for slope stability evaluation and meeting the high precision and rapidity requirements in slope engineering.The data set of this study includes five parameters,namely slope height,slope angle,cohesion,internal friction angle,and peak ground acceleration.The available data is split into two categories:training(75%)and test(25%)sets.The output of the RT and REP tree models is evaluated using performance measures including accuracy(Acc),Matthews correlation coefficient(Mcc),precision(Prec),recall(Rec),and F-score.The applications of the aforementionedmethods for predicting slope stability are compared to one another and recently established soft computing models in the literature.The analysis of the Acc together with Mcc,and F-score for the slope stability in the test set demonstrates that the RT achieved a better prediction performance with(Acc=97.1429%,Mcc=0.935,F-score for stable class=0.979 and for unstable case F-score=0.935)succeeded by the REP tree model with(Acc=95.4286%,Mcc=0.896,F-score stable class=0.967 and for unstable class F-score=0.923)for the slope stability dataset The analysis of performance measures for the slope stability dataset reveals that the RT model attains comparatively better and reliable results and thus should be encouraged in further research.

Static aerobic composting of municipal sewage sludge with forced ventilation:Using matured compost as bulking conditioner

Static aerobic composting of municipal sewage sludge with forced ventilation or air ventilation using matured compost as bulking conditioner was investigated.Physical and chemical parameters,e.g.,temperature,moisture content,VSS,CODcr,pH,and germination index(GI),were analyzed to characterize the composting process.Fermentation starts quickly in both forced and air ventilation compost heaps and reaches high-temperature stage after 2 d,owing to the bulking function of matured compost.Compared to air ventilation,however,forced ventilation enables the high-temperature stage to last longer for approximately 7 d.The moisture content of both compost bodies decreases from 62% to about 50% as a result of evaporation,and it decreases slightly faster in forced ventilation compost heap after 13 d due to the higher temperature and better ventilation condition.Although no obvious differences of VSS and pH are observed between both compost heaps,the soluble CODCr and GI show differences during the second half period of fermentation.In forced ventilation compost,the soluble CODCr has a small rebound after 13 d,and GI decreases from 46% to 35% but then increases.These results show that in general,the matured compost is a good conditioner and force ventilation with a proper air supply strategy can be more efficient than air ventilation.

模块化多电平铁路功率调节器接入的机车混跑车网耦合系统稳定性分析

基于模块化多电平换流器的铁路功率调节器(modular multilevel converter-railway static power conditioner,MMCRPC)能够有效解决牵引供电系统存在的电能质量问题,但接入MMC-RPC对车网耦合系统低频稳定性的影响尚不明确。针对此问题,首先考虑频率耦合效应,基于多谐波线性化方法建立了CRH3型、CRH5型机车变流器及MMC-RPC的端口序导纳模型,并实现了不同控制策略、不同变流器负荷序导纳模型在单相静止坐标系的统一。其次,分别研究了MMC-RPC接入牵引网前后车网耦合系统的低频振荡现象。接着,根据主导相角裕度和灵敏度指标首次定量评估了MMC-RPC接入机车混跑系统工况下不同控制器参数对系统稳定性的影响,并提出相应调参准则以提升系统稳定性。最后基于Matlab/Simulink仿真和硬件在环半实物实时仿真验证了对系统稳定性分析结果的正确性。

Evaluation of slope stability through rock mass classification and kinematic analysis of some major slopes along NH-1A from Ramban to Banihal, North Western Himalayas

The network of Himalayan roadways and highways connects some remote regions of valleys or hill slopes,which is vital for India’s socio-economic growth.Due to natural and artificial factors,frequency of slope instabilities along the networks has been increasing over last few decades.Assessment of stability of natural and artificial slopes due to construction of these connecting road networks is significant in safely executing these roads throughout the year.Several rock mass classification methods are generally used to assess the strength and deformability of rock mass.This study assesses slope stability along the NH-1A of Ramban district of North Western Himalayas.Various structurally and non-structurally controlled rock mass classification systems have been applied to assess the stability conditions of 14 slopes.For evaluating the stability of these slopes,kinematic analysis was performed along with geological strength index(GSI),rock mass rating(RMR),continuous slope mass rating(CoSMR),slope mass rating(SMR),and Q-slope in the present study.The SMR gives three slopes as completely unstable while CoSMR suggests four slopes as completely unstable.The stability of all slopes was also analyzed using a design chart under dynamic and static conditions by slope stability rating(SSR)for the factor of safety(FoS)of 1.2 and 1 respectively.Q-slope with probability of failure(PoF)1%gives two slopes as stable slopes.Stable slope angle has been determined based on the Q-slope safe angle equation and SSR design chart based on the FoS.The value ranges given by different empirical classifications were RMR(37-74),GSI(27.3-58.5),SMR(11-59),and CoSMR(3.39-74.56).Good relationship was found among RMR&SSR and RMR&GSI with correlation coefficient(R 2)value of 0.815 and 0.6866,respectively.Lastly,a comparative stability of all these slopes based on the above classification has been performed to identify the most critical slope along this road.

UAV-mounted Ground Penetrating Radar: an example for the stability analysis of a mountain rock debris slope

This paper describes scientific research conducted to highlight the potential of an integrated GPR-UAV system in engineering-geological applications.The analysis focused on the stability of a natural scree slope in the Germanasca Valley,in the western Italian Alps.As a consequence of its steep shape and the related geological hazard,the study used different remote sensed methodologies such as UAV photogrammetry and geophysics survey by a GPR-drone integrated system.Furthermore,conventional in-situ surveys led to the collection of geological and geomorphological data.The use of the UAV-mounted GPR allowed us to investigate the bedrock depth under the detrital slope deposit,using a non-invasive technique able to conduct surveys on inaccessible areas prone to hazardous conditions for operators.The collected evidence and the results of the analysis highlighted the stability of the slope with Factors of Safety,verified in static conditions(i.e.,natural static condition and static condition with snow cover),slightly above the stability limit value of 1.On the contrary,the dynamic loading conditions(i.e.,seismic action applied)showed a Factor of Safety below the stability limit value.The UAV-mounted GPR represented an essential contribution to the surveys allowing the definition of the interface debris deposit-bedrock,which are useful to design the slope model and to evaluate the scree slope stability in different conditions.

MMC-RPC的多维泰勒网优化控制策略

为进一步解决铁路牵引供电系统中无功功率、负序电流和谐波失真率高等对电能质量的影响,将多维泰勒网(Multi-dimensional Taylor Network,MTN)优化控制应用于与模块化多电平换流器结合的铁路功率调节器(Railway Power Conditioner with Modular Multilevel Converter,MMC-RPC)。相比传统双闭环PI控制器,多维泰勒网控制器的优点在于抗扰动能力更强、鲁棒性更好和谐波失真率更低等。针对参数整定问题,将dq轴电流参考值与实际值之间误差平方的积分作为输出性能指标,并运用粒子群算法对MTN当中的参数进行优化。在MATLAB/Simulink软件中分别搭建了MMC-RPC采用MTN控制器和PI控制器的仿真模型,对电气化铁路中常见的一侧供电臂有机车负载和负载突变2种常见工况进行对比,验证了MTN控制器在MMC-RPC中的可行性和优越性。

变频空调引起辅助逆变器200%过载故障的原因分析及解决措施

介绍某地铁列车辅助逆变器(SIV)工作原理及组成结构,分析了车辆辅助逆变器输出200%过载故障产生原理。通过多种试验模拟重现辅助逆变器输出200%过载故障,确定引起该故障的原因为变频空调中的可控硅整流桥故障。对故障原因进行了深入分析,对辅助供电系统设备的维护提供参考。

一种考虑再生制动能量反馈的混合铁路功率调节器

为低成本地解决高速铁路或重载铁路牵引供电系统中的三相电流不平衡问题,提出了一种考虑电力机车再生制动能量反馈的混合铁路功率调节器HRPC(hybrid railway power conditioner)对负序电流进行补偿。HRPC由模块化RPC和所提的一种新型静止无功补偿器SVC(static var compensator)组成。首先,详细介绍了HRPC的拓扑结构及其工作原理,分析了列车不同运行工况下的三相电流不平衡度及负序补偿原理。然后,设计了模块化RPC和新型SVC的控制策略。最后进行了仿真验证。仿真结果表明,所提HRPC具有较好的负序补偿能力,且降低了补偿装置的成本,易于工程应用。

高速电气化铁路新型电能质量补偿系统

针对高速电气化铁路牵引供电系统面临的谐波电流含量高且较分散、负序电流大的电能质量问题,建立一种新型电能质量补偿系统。该系统主要由电气化铁路功率调节器、两组晶闸管控制电抗器和两组晶闸管控制3次滤波器组成,其中电气化铁路功率调节器只用来转移有功功率和治理部分谐波,3次滤波器用于滤除3次谐波和改变供电臂电流相角,电抗器也用来改变供电臂电流相角。该系统以最小的有源容量和较低的成本进行谐波抑制和负序电流补偿。本文在阐述其工作原理的基础上,建立了其基波域和谐波域的统一等效电气模型,并深入研究了其负序补偿和谐波抑制原理,分析了电气化铁路功率调节器最佳容量选取的原则,同时还对整个系统的谐振特性进行了分析,并模拟京沪高速电气化铁路实际供电系统进行了仿真,仿真结果验证了本文研究内容的正确性和有效性。

V/V牵引供电系统中铁路功率调节器的控制方法研究

针对电气化铁路高负序含量、谐波污染等电能质量问题,讨论一种能够进行负序与谐波综合补偿的铁路功率调节器(railway static power conditioner,RPC)。为了提高RPC的控制性能与效果,构建RPC的电流内环基于重复预测的无差拍控制和电压外环的复合准PI控制的双环控制策略,实现了对参考电流信号的快速、平滑跟踪和直流侧电压的平稳控制。考虑到系统模型参数的扰动性与波动性,通过采用基于遗忘因子的递推最小二乘算法来动态辨识系统参数,增强控制系统的适应性。最后进行仿真和实验验证,结果证实了所提方法的正确性。

一种基于超级电容储能系统的新型铁路功率调节器

在采用铁路功率调节器解决电气化铁路电能质量问题时,为了提高再生制动能量的利用率,提出一种由铁路功率调节器和超级电容储能系统构成的新型储能式铁路功率调节器。该系统不仅能实现两供电臂能量双向流通,还能通过铁路功率调节器和储能系统的协调控制,提高再生制动能量利用率并实现削峰填谷功能。首先分析系统工作原理,构建再生制动工况下的等效电路,推导再生制动能量利用率表达式;然后分析该系统能够提高再生制动能量利用率并实现削峰填谷功能的原因;最后搭建仿真模型和实验平台,多种工况下的实验结果表明了所提新型补偿系统的正确性及有效性。

基于模块化多电平的铁路功率调节器直接功率控制策略

为解决铁路供电负序问题,同时兼顾无功补偿与谐波治理,由2个单相模块化多电平换流器(modular multilevel converter,MMC)背靠背连接构造铁路功率调节器(MMC-RPC),并直接接入牵引网。较传统RPC而言,取消了降压变压器,提高了直流电压,减小了直流端电流。针对铁路供电,分析单相系统的电压与功率间的数学模型,设计了一种无需系统角频率和电感参数的直接功率控制策略(direct power control,DPC)。以V/v牵引变为例,在Matlab/Simulink中搭建仿真模型,仿真结果验证了所提策略的有效性。

电磁混合式高铁供电系统负序优化补偿方法

由高速铁路牵引负荷不对称性所产生的负序电流,对发电、供电设备安全和可靠运行产生严重影响。本文在分析高铁供电系统负序产生机理和现有负序补偿方法的基础上,提出一种基于小容量的铁路功率调节器(RPC)和大容量的磁控静止无功补偿器(MSVC)的电磁混合式高铁无功和负序综合补偿系统(EHCS)。从理论上分别求出完全补偿无功、负序和满足无功、负序国家标准的优化补偿条件下,EHCS的最小安装容量及其最优协同策略。最后分别对EHCS进行完全补偿和优化补偿条件进行了仿真和实验分析,仿真及实验结果证明了本文所提方法的有效性。

大功率混合型电气化铁路功率补偿装置

针对高速电气化铁路牵引供电系统面临的负序、谐波等电能质量问题,提出一种新型混合电能质量补偿系统。该系统主要由铁路功率调节器(RPC)、晶闸管控制电抗器和三次滤波器组成。为了达到负序与谐波综合治理的目的,首先采用无源装置分别给两个供电臂补偿固定容量的容性与感性电流来改变两供电臂电流相位差,然后RPC根据补偿情况来转移相应量的有功、补偿余额的无功并补偿指定量的谐波,这样大大减小了有源部分的容量,节省了成本,提高了系统的可靠性。考虑到电流内环指令信号的交流特性,故采用了一种模糊递推PI控制方法并能够很好地消除稳态误差,并提高系统的动态性能。根据补偿要求设计了补偿装置参数,最后仿真与实验结果验证了本文研究内容的正确性。

考虑供电臂电压波动的铁路功率调节器多目标优化设计

在采用铁路功率调节器(RPC)解决牵引供电系统电能质量问题时,RPC补偿电流会在一定程度上加剧两供电臂的电压波动,从而可能引起牵引网欠电压或过电压问题。在保证RPC综合治理效果的前提下,为了既能有效减少RPC补偿容量,又能尽量缓解两供电臂电压波动,本文以供电臂电压波动度和RPC补偿容量作为优化目标,提出一种RPC多目标优化设计方法。本文分析RPC补偿电流加剧两供电臂电压波动的原因,引入供电臂电压波动度指标,建立RPC多目标优化数学模型,并采用粒子群多目标优化算法求解。算例分析和实验验证了该方法可有效减小系统两供电臂电压波动并减少RPC补偿容量。

一种新颖的铁路静止功率调节器双环控制方法

为治理由电力机车而引起的牵引供电系统的负序、谐波等电能质量问题,研究了一种先进的铁路静止功率调节器,同时为了改善功率调节器的治理效果与控制性能,本文构建了一种新颖的电压电流双环控制框图。考虑到内环电流跟踪的重要性,提出了一种基于递推积分的双滞环复合控制方法,有机结合了两种控制方法的特性,实现了两种控制方法的优缺点互补,提高了电流跟踪的速度和精度。为了稳定直流侧电压以保证调节器的正常稳定工作,根据功率调节器的结构和能量平衡原理,提出了一种直流侧电压的复合准PI控制方法,从而实现了对电压的平滑、稳定控制。最后,通过仿真和实验验证了本文所提出的控制方法的正确性,有效地改善了牵引网的电能质量问题。

采用V/v变压器的高速铁路牵引供电系统负序和谐波综合补偿方法

为解决高速铁路牵引供电系统中的负序、谐波电能质量问题,提出采用铁路功率调节器(railway static power conditioner,RPC)进行负序和谐波电流综合治理。RPC包含共用直流侧电容的背靠背形式的两变流器,控制其功率能够实现负序补偿和谐波抑制。分析RPC的基本结构和补偿原理后,提出三相V/v变压器下负序和谐波补偿电流检测方法,为保证RPC直流侧电压稳定和实现负序和谐波补偿,提出RPC直流侧电压和两变流器电流控制策略。最后,进行仿真验证。仿真结果表明,在该文提出的负序和谐波检测方法及控制策略下,RPC具有良好的负序和谐波补偿性能。

电气化铁路并联型铁路功率调节器控制策略的仿真研究

为解决电气化铁路牵引供电系统中三相网侧谐波、无功和负序等电能质量问题,同时满足电气化铁路补偿容量大的要求,提出了采用并联型铁路功率调节器(railway static power conditioner,RPC)配合降压变压器的综合补偿方案,具体研究了并联型RPC的控制策略并进行了仿真分析。提出了对RPC的指令电流检测采用平衡补偿电流检测法,对RPC的补偿电流控制采用基于比例谐振(proportion resonance,PR)控制器的三角波比较控制方式,同时将载波相移(carrier phase shift,CPS)技术应用于RPC的控制。最后,利用MATLAB/Simulink搭建了由2个RPC并联构成的补偿方案的仿真模型。仿真结果表明:RPC投入运行后,三相网侧电流为与电网电压同相位的三相正弦对称电流,只含有开关频率整数倍次的高次谐波;通过进一步采用CPS技术,开关频率奇数倍次的高次谐波被有效滤除,三相网侧电流总谐波畸变率由8.04%降低为2.24%。仿真结果验证了并联型RPC在解决牵引供电系统中三相网侧电流谐波、无功和负序等电能质量问题方面的可行性与优越性,为并联型RPC的工程应用提供了有价值的参考。