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Effects of leakage and friction on the miniaturization of a Wankel compressor

Yilin ZHANG, Wen WANG

《能源前沿（英文）》 2011年第5卷第1期页码 83-92 doi: 10.1007/s11708-010-0125-7

摘要： This paper presents a numerical simulation of the performance of a meso-scale Wankel compressor and discusses the factors affecting its miniaturization. The discussion is related to the effect of leakage and friction on the design limit (cooling capacity and dimension) of the meso Wankel compressor. In the simulation, the main leakage comes from the gaps between the rotor and the endplates as well as between the seal apex and the cylinder. The largest friction originates from the clearance among the end face of the eccentric shaft, the end faces of the rotor, and the endplates. The decreasing cooling capacity of the meso Wankel compressor increases the proportion of leakage to displacement and causes the coefficient of performance COP and the mechanical efficiency to decrease. The rational design cooling capacity limit for the meso-scale Wankel compressor is approximately 4 W.

关键词： meso-scale Wankel compressor leakage friction

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Experimental study of pollution effect on the behavior of high voltage insulators under alternative current

Hani BENGUESMIA, Nassima M’ZIOU, Ahmed BOUBAKEUR

《能源前沿（英文）》 2021年第15卷第1期页码 213-221 doi: 10.1007/s11708-017-0479-1

摘要： In this paper, the impact of the conductivity and the distribution of pollution on the behavior of the high voltage insulator cap and pin 1512L, artificially polluted is described. An experimental model in form of a disc is proposed. This experimental model reproduces the real model which is the 1512L insulator. Besides, a comparative study is presented. For this comparative study, different solutions are adopted to s`imulate the pollution (containing NaCl+ distilled water) that has different conductivities for a discontinuous distribution of the pollution on the insulator under an AC voltage. Furthermore, the influence of the pollution on the flashover voltage and the leakage current is studied. Finally, the behavior of real and experimental model of the insulator is investigated.

关键词： 1512L insulator circular model artificial pollution flashover leakage current discontinuous pollution high voltage

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Long-term settlement behavior of ground around shield tunnel due to leakage of water in soft deposit

Huaina WU, Yeshuang XU, Shui-long SHEN, Jin-chun CHAI

《结构与土木工程前沿（英文）》 2011年第5卷第2期页码 194-198 doi: 10.1007/s11709-011-0105-y

摘要： The lining of shield tunnel is usually composed of segments, in which the joints, cracks, and the grouting holes (hereafter called lining deficit) exist. During the long-term running, soils and groundwater may leak from these kinds of lining deficit. The leaking of soil and groundwater causes the long-term ground loss around tunnel and thus results in the settlement of ground surface. This paper aims to analyze the impact of the leakage of groundwater through segments on the long-term settlement of ground surface. The adopted analytical method is based on the theory of groundwater seepage by using numerical simulation. The analyzed results show that settlement of ground surface increases gradually with the increase of the leaked volume of tunnel segments. When the leaked volume was unevenly distributed, differential settlement occurred locally. Comparative analysis by changing the leaked volume was conducted. The results reveal that there is a linear relationship between settlement and leaked volume when the leaked volume was controlled within the allowable limit.

关键词： lining deficit leakage of water shield tunnel settlement soft deposit

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A building unit decomposition model for energy leakage by infrared thermography image analysis

Yan SU, Fangjun HONG, Lianjie SHU

《能源前沿（英文）》 2020年第14卷第4期页码 901-921 doi: 10.1007/s11708-020-0679-y

摘要： A quantitative energy leakage model was developed based on the thermography image data measured for both external and internal building surfaces. The infrared thermography images of both surfaces of doors, windows, and walls of an office building in the Hengqin Campus of University of Macao were taken at various times in a day for four seasons. The transient heat ﬂux for sample units were obtained based on measurements of the seasonal transient local temperature differences and calculations of the effective thermal conductivity from the multiple-layer porous medium conduction model. Effects of construction unit types, orientations, and seasons were quantitatively investigated with unit transient orientation index factors. The corresponding electric energy consumption was calculated based on the air conditioning system coefficient of performance of heat pump and refrigerator cycles for different seasons. The model was validated by comparing to the electric meter records of energy consumption of the air conditioning system. The uncertainties of the predicted total building energy leakage are about 14.7%, 12.8%, 12.4%, and 15.8% for the four seasons, respectively. The differences between the predicted electric consumption and meter values are less than 13.4% and 5.4% for summer and winter, respectively. The typical daily thermal energy leakage value in winter is the highest among the four seasons. However, the daily electric energy consumption by the air conditioning system in summer and autumn is higher than that in winter. The present decomposition model for energy leakage is expected to provide a practical tool for quantitative analysis of energy leakage of buildings.

关键词： heat conductivity heat coefficient heat &fllig ux infrared thermography thermal image

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Aggravation of membrane fouling and methane leakage by a three-phase separator in an external anaerobic

Chao Pang, Chunhua He, Zhenhu Hu, Shoujun Yuan, Wei Wang

《环境科学与工程前沿（英文）》 2019年第13卷第4期 doi: 10.1007/s11783-019-1131-6

摘要：

The existence of three-phase separator did not affect COD removal in the EAnCMBR.

The existence of three-phase separator aggravated methane leakage of EAnCMBR.

The existence of three-phase separator aggravated membrane fouling rate of EAnCMBR.

Start-up of EAnCMBR equipped three-phase separator was slightly delayed.

关键词： Anaerobic membrane bioreactor Three-phase separator Membrane fouling Methane leakage Sludge property

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Leakage location system for oil pipeline on basis of stress wave detection

WANG Bangfeng, CHEN Renwen

《机械工程前沿（英文）》 2008年第3卷第3期页码 307-312 doi: 10.1007/s11465-008-0047-9

摘要： An online monitoring system was developed for rapidly determining the exact location of the holing position in an oil pipeline by monitoring and analyzing the characteristics of the strain wave caused by the hole. The system has a master-slaver computer structure based on a remote wireless network. The master system takes charge of managing and controlling the whole system, identifying the holing stress wave, and calculating the holing position. The slaver system is responsible for sampling the strain wave signal from the pipeline. The characteristics of the strain wave signal are extracted by a Hilbert-Huang transform based on a signal processing approach. The exact holing position can be obtained by a time delay locating method with stress wave characteristics. The experimental results of the in-service pipeline show that the average locating error of the system is less than 10 m, the accuracy ratio for the holing alarm is more than 90%, and the time that the system takes to respond to the leakage is less than 10 s.

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利用机器视觉技术对化工厂管道进行自动视觉泄漏检测与定位 Reiew

Mina Fahimipirehgalin, Emanuel Trunzer, Matthias Odenweller, Birgit Vogel-Heuser

《工程（英文）》 2021年第7卷第6期页码 758-776 doi: 10.1016/j.eng.2020.08.026

摘要：

在大型化工厂中，输送液体的管道的泄漏是一个重要的问题。管道的破损不仅会影响工厂的正常运行，同时也增加了维护成本。此外，还会使操作人员的生命安全受到威胁。因此，管道泄漏的检测与定位是维护和状态监测中的关键任务。近年来，大型工厂利用红外（IR）相机进行泄漏检测。红外相机可捕捉温度比周围环境温度高（或低）的液体泄漏。本文针对化工厂中的管道泄漏，提出了一种基于红外视频数据和机器视觉技术的检测与定位方法。由于所提出的方法是以视觉技术为基础，无需考虑泄漏液体的物理性质，因此其适用于任何类型的液体（水、油等）泄漏检测。在本方法中，首先对后续帧进行减影和分块处理，然后对每一分块进行主成分分析，提取特征；接着将分块内所有减影帧都转换为特征向量（作为块分类的依据），根据特征向量，采用k-最近邻算法将块分为正常（无泄漏）和异常（泄漏）两类；最后在各异常块上确定泄漏的位置。本文使用了两种不同格式的数据集（由红外相机拍摄的实验室工厂演示装置的视频图像组成）对上述方法进行评估。结果表明，本文提出的利用红外视频进行管道泄漏检测与定位的方法前景可观，具有较高的检测精度以及合理的检测时间。本文最后讨论了该方法在工厂进行实际推广的可能性及局限性。

关键词：泄漏检测与定位图像分析图像预处理主成分分析 k-最近邻分类

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Modeling and analysis of magnetic dipoles in weak magnetic field

WANG Zhaoxia, ZHANG Weimin, LIU Hongguang

《机械工程前沿（英文）》 2008年第3卷第2期页码 222-225 doi: 10.1007/s11465-008-0028-z

摘要： The magnetic leakage field distribution resulting from linear defects of a tube sample in the geomagnetic field is modeled according to the magnetic dipole theory. The formula to compute the normal component of the weak magnetic field is deduced based on the spatial distribution of the magnetic dipole. The shape and characteristics of the zero line (an important criterion for magnetic memory testing) of the normal field is analyzed under different longitudinal magnetizations. Results show that the characteristics of the zero line should be considered when the metal magnetic memory testing method is used to find and locate the defect.

关键词： geomagnetic theory important criterion magnetic leakage normal component

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Effect of current density on groundwater arsenite removal performance using air cathode electrocoagulation

《环境科学与工程前沿（英文）》 2021年第15卷第6期 doi: 10.1007/s11783-021-1399-1

摘要：

• With the same charge, current density had little effect on As(III) removal in ACEC.

关键词： Electrocoagulation Air cathode Arsenic Current density Energy consumption

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矿井低压电网选择性漏电保护系统总体设计与实现

孙玉坤,朱志莹,黄振跃,唐平

《中国工程科学》 2012年第14卷第7期页码 93-97

摘要：

设计了一款以dsPIC30F4012为主控制器、PIC16F877A为从处理器的新型主从式选择性漏电保护系统。该系统在总开关处采用附加直流源检测原理检测是否发生漏电，在分支开关处使用零序功率方向检测原理判断发生漏电故障线路，给出了保护系统的硬件框图和软件流程图，并且采用速度更快的RS—485总线及光纤传输技术，实现了矿井低压电网漏电保护的瞬动性。实验结果验证了该保护系统的优越性能。

关键词：漏电保护选择性 dsPIC30F4012 PIC16F877A RS—485总线光纤通信

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EGG PRODUCTION IN CHINA: CURRENT STATUS AND OUTLOOK

Ning YANG

《农业科学与工程前沿（英文）》 2021年第8卷第1期页码 25-34 doi: 10.15302/J-FASE-2020363

摘要： Eggs are one of the most nutritious and affordable animal products worldwide. From 1985, egg production in China has retained the leading place in the world. A total of 33 Mt of eggs were produced in 2019 representing ˃ 40% of the world total production. Egg production in China is characterized by diversity in several aspects, including layer breeds, products and production systems. New breeds and synthetic lines are developed to improve the genetic potentials of egg production and feed efficiency of layers. In the past, layer farms were run mostly by small households with 100 to 1000 layers per farm. Over the past decades, egg production in China has developed toward standardization and expansion of production systems, and many of these modern intensive farms raise millions of layers. Although the Chinese egg products maintain strong competitiveness over other animal products and imported egg products, the egg industry will grow at a slower pace compared to the past. Chinese consumers are more concerned about the quality and safety of eggs and egg products, as well as the environmental issues related to animal production, which presents challenges for the Chinese egg industry.

关键词： poultry farms China diversity egg production trends

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EGG PRODUCTION IN CHINA: CURRENT STATUS AND OUTLOOK

《农业科学与工程前沿（英文）》 2021年第8卷第1期页码 25-34

摘要：

• China is now the largest egg production country worldwide

• Egg production in China is characterized by diversity in several aspects

• China is now capable of breeding new varieties, with more than 50% of the market share

• Policies have been implemented to ensure sustainable development of egg production

• Integrating crop-chicken-vegetable production system is established

Eggs are one of the most nutritious and affordable animal products worldwide. From 1985, egg production in China has retained the leading place in the world. A total of 33 Mt of eggs were produced in 2019 representing ˃ 40% of the world total production. Egg production in China is characterized by diversity in several aspects, including layer breeds, products and production systems. New breeds and synthetic lines are developed to improve the genetic potentials of egg production and feed efficiency of layers. In the past, layer farms were run mostly by small households with 100 to 1000 layers per farm. Over the past decades, egg production in China has developed toward standardization and expansion of production systems, and many of these modern intensive farms raise millions of layers. Although the Chinese egg products maintain strong competitiveness over other animal products and imported egg products, the egg industry will grow at a slower pace compared to the past. Chinese consumers are more concerned about the quality and safety of eggs and egg products, as well as the environmental issues related to animal production, which presents challenges for the Chinese egg industry.

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基于迭代算法的有源电力滤波器谐波电流实时检测新方法

李自成,孙玉坤

《中国工程科学》 2006年第8卷第1期页码 46-50

摘要：

目前，已经提出了多种有源电力滤波器谐波及无功电流检测方法，尽管这些方法各有特点，但都存在着难以克服的问题，如计算量大，实时性差，检测精度不高等。文章在负载电流分析的基础上，提出了一种基于迭代算法的有源电力滤波器谐波电流实时检测方法，该方法具有计算量非常小，实时性好，检测精度高等特点。理论分析与仿真研究证实了该方法的正确性。

关键词：有源电力滤波器谐波电流有功电流无功电流

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电力系统中对称和/或不对称故障的限流器阻抗优化新方法 None

Mahmoud MODARESI, Hamid LESANI

《信息与电子工程前沿（英文）》 2018年第19卷第2期页码 297-307 doi: 10.1631/FITEE.1601689

摘要：为给电力网络设计者选择故障限流器（fault current limiters，FCLs）的阻抗类型和阻值，提出一种基于其在网络中的位置计算最佳FCL阻值的新方法。

关键词：故障限流器（FCL）；FCL阻抗；短路电流；故障电流；电力系统

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Circumcision of preschool boys in Baghdad, Iraq: prevalence, current practice and complications

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《医学前沿（英文）》 2013年第7卷第1期页码 122-125 doi: 10.1007/s11684-013-0242-x

摘要：

Circumcision is probably one of the most ancient surgical operations and has been performed more than any other operation. The aim of this study is to assess the prevalence of circumcision in preschool boys and to present an overview of the current practices and complications in Baghdad, Iraq. A statistical survey was conducted at the Central Teaching Hospital for Children in Baghdad, Iraq during the period April 2003 to October 2004. The survey consisted of structured interviews with the accompanying parents while waiting for their children’s routine appointments. A total of 4000 boys were included. 2 443 (61%) were circumcised and the prevalence of circumcision increased from 18% at 6 months of age to reach 92% at 6 years. Only 180 (7.4%) boys had a medical reason while the rest were circumcised for religious reasons. Parents were the only determinant in deciding the time and place of religious circumcision. Circumcision was performed by a doctor in 732 (30%) boys, by a nurse in 1276 (52%) and by a traditional circumciser in 435 (18%). Post-operative complications were encountered in 209 (8.5%) boys. Circumcision is an important surgical procedure that should be performed by trained medical staff in medical institutions. Circumcision performed by medical professionals caused significantly less complications.

关键词： circumcision children prevalence religious complications