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Transforming the Loess Plateau of China

Yuheng LI,Guoming DU,Yansui LIU

《农业科学与工程前沿(英文)》 2016年 第3卷 第3期   页码 181-185 doi: 10.15302/J-FASE-2016110

摘要: This paper aims to show the importance of land consolidation in transforming the Loess Plateau of China. The paper comprehensively analyzes how over recent decades the Grain for Green Project and Gully Land Consolidation Project jointly transformed the ecology and landscape of the Loess Plateau and the livelihood of its residents. The findings show that these two projects have achieved a balance between green protection, new land creation, and improved food security and livelihood of local people in the hilly areas of China. The paper points out that the successful transformation of the Plateau lies in a holistic approach incorporating various components of the human and natural systems. Finally, the paper highlights the necessity of retaining these two land consolidation projects as part of an ongoing policy in the mountain and hilly areas of China, changing agricultural management to suit the new relationship between humans and the land.

关键词: China     critical zone     land consolidation     Loess Plateau     sustainability    

Applying the multi-zone model in predicting the operating range of HCCI engines

Ming JIA, Maozhao XIE, Zhijun PENG,

《能源前沿(英文)》 2010年 第4卷 第3期   页码 414-423 doi: 10.1007/s11708-010-0108-8

摘要: In this paper, a multi-zone model is developed to predict the operating range of homogeneous charge compression ignition (HCCI) engines. The boundaries of the operating range were determined by knock (presented by ringing intensity), partial burn (presented by combustion efficiency), and cycle-to-cycle variations (presented by the sensitivity of indicated mean effective pressure to initial temperature). By simulating an HCCI engine fueled with iso-octane, the knock and cycle-to-cycle variations predicted by the model showed satisfactory agreement with measurements made under different initial temperatures and equivalence ratios; the operating range was also well reproduced by the model. Furthermore, the model was applied to predict the operating range of the HCCI engine under different engine speeds by varying the intake temperatures and equivalence ratios. The potential to extend the operating range of the HCCI engine through two strategies, i.e., variable compression ratio and intake pressure boosting, was then investigated. Results indicate that the ignition point can be efficiently controlled by varying the compression ratio. A low load range can be extended by increasing the intake temperature while reducing the compression ratio. Higher intake temperatures and lower compression ratios can also extend the high load range. Boosting intake pressure is helpful in controlling the combustion of the HCCI engine, resulting in an extended high load range.

关键词: homogeneous charge compression ignition (HCCI) engine     multi-zone     operating range    

Microbial biodegradation of plastics: Challenges, opportunities, and a critical perspective

《环境科学与工程前沿(英文)》 2022年 第16卷 第12期 doi: 10.1007/s11783-022-1596-6

摘要:

● Health hazards of plastic waste on environment are discussed.

关键词: Plastic-waste     Polymers     Health-hazards     Biodegradation     Microorganisms     Enzymes    

Machine learning in building energy management: A critical review and future directions

《工程管理前沿(英文)》 2022年 第9卷 第2期   页码 239-256 doi: 10.1007/s42524-021-0181-1

摘要: Over the past two decades, machine learning (ML) has elicited increasing attention in building energy management (BEM) research. However, the boundary of the ML-BEM research has not been clearly defined, and no thorough review of ML applications in BEM during the whole building life-cycle has been published. This study aims to address this gap by reviewing the ML-BEM papers to ascertain the status of this research area and identify future research directions. An integrated framework of ML-BEM, composed of four layers and a series of driving factors, is proposed. Then, based on the hype cycle model, this paper analyzes the current development status of ML-BEM and tries to predict its future development trend. Finally, five research directions are discussed: (1) the behavioral impact on BEM, (2) the integration management of renewable energy, (3) security concerns of ML-BEM, (4) extension to other building life-cycle phases, and (5) the focus on fault detection and diagnosis. The findings of this study are believed to provide useful references for future research on ML-BEM.

关键词: building energy management     machine learning     integrated framework     knowledge evolution    

delamination on the stiffness of composite pipes under compressive transverse loading using cohesive zone

Sattar MALEKI, Roham RAFIEE, Abolfazl HASANNIA, Mohammad Reza HABIBAGAHI

《结构与土木工程前沿(英文)》 2019年 第13卷 第6期   页码 1316-1323 doi: 10.1007/s11709-019-0555-1

摘要: The effect of delamination on the stiffness reduction of composite pipes is studied in this research. The stiffness test of filament wound composite pipes is simulated using cohesive zone method. The modeling is accomplished to study the effect of the geometrical parameters including delamination size and its position with respect to loading direction on stiffness of the composite pipes. At first, finite element results for stiffness test of a perfect pipe without delamination are validated with the experimental results according to ASTM D2412. It is seen that the finite element results agree well with experimental results. Then the finite element model is developed for composite pips with delaminated areas with different primary shapes. Thus, the effect of the size of delaminated region on longitudinal and tangential directions and also its orientation with respect to loading direction on delamination propagation and stiffness reduction of the pipes is assessed.

关键词: delamination     composite pipes     stiffness test     cohesive zone method    

Reducing environmental impacts through socioeconomic transitions: critical review and prospects

《环境科学与工程前沿(英文)》 2023年 第17卷 第2期 doi: 10.1007/s11783-023-1624-1

摘要:

● Reducing environmental impacts through socioeconomic structural transitions.

关键词: Environmental pressures     Environmental impacts     Nexus     Supply chains     Trade     Coupled systems    

Advances in airborne microorganisms detection using biosensors: A critical review

《环境科学与工程前沿(英文)》 2021年 第15卷 第3期 doi: 10.1007/s11783-021-1420-8

摘要:

Humanity has been facing the threat of a variety of infectious diseases. Airborne microorganisms can cause airborne infectious diseases, which spread rapidly and extensively, causing huge losses to human society on a global scale. In recent years, the detection technology for airborne microorganisms has developed rapidly; it can be roughly divided into biochemical, immune, and molecular technologies.

关键词: Biosensor     Airborne microorganisms     Microbiological detection technology    

渤海辽东带地质认识的突破与金县1-1大油田的发现

邓运华

《中国工程科学》 2011年 第13卷 第10期   页码 13-18

摘要:

辽东带系指渤海辽中凹陷的东部陡坡带及辽东凸起,被辽中及辽东凹陷所夹持。辽东带油源条件好,东营组储—盖条件优越,断鼻、断块圈闭发育。但在2002年之前的15年内,国内外公司在辽东带进行了长期研究和勘探,钻了12口探井,没有发现商业油气田。经过对辽东带油气地质条件3年的深入研究,对每口失利井原因进行了再次分析,认识到该带发育东营组及沙河街组两套主力成藏组合,控制东营组成藏的主要因素是油气运移,而沙河街组能否成藏关键是储层。在此认识指导下选择研究方向,评价有利目标,经钻探发现了金县1-1大油田,储量达1.5×108 m3,充分显示了科研在油气勘探中的作用。

关键词: 渤海辽东带     金县1-1     地质认识     大油田    

effects of mismatch fracture properties in encapsulation-based self-healing concrete using cohesive-zone

Luthfi Muhammad MAULUDIN, Chahmi OUCIF, Timon RABCZUK

《结构与土木工程前沿(英文)》 2020年 第14卷 第3期   页码 792-801 doi: 10.1007/s11709-020-0629-0

摘要: Finite element analysis is developed to simulate the breakage of capsule in capsule-based self-healing concrete. A 2D circular capsule with different core-shell thickness ratios embedded in the mortar matrix is analyzed numerically along with their interfacial transition zone. Zero-thickness cohesive elements are pre-inserted into solid elements to represent potential cracks. This study focuses on the effects of mismatch fracture properties, namely fracture strength and energy, between capsule and mortar matrix into the breakage likelihood of the capsule. The extensive simulations of 2D specimens under uniaxial tension were carried out to investigate the key features on the fracture patterns of the capsule and produce the fracture maps as the results. The developed fracture maps of capsules present a simple but valuable tool to assist the experimentalists in designing appropriate capsule materials for self-healing concrete.

关键词: self-healing concrete     interfacial zone     capsule materials     cohesive elements     fracture maps    

Effects of critical geometric parameters on the optical performance of a conical cavity receiver

Hu XIAO, Yanping ZHANG, Cong YOU, Chongzhe ZOU, Quentin FALCOZ

《能源前沿(英文)》 2019年 第13卷 第4期   页码 673-683 doi: 10.1007/s11708-019-0630-2

摘要: The optical performance of a receiver has a great influence on the efficiency and stability of a solar thermal power system. Most of the literature focuses on the optical performance of receivers with different geometric shapes, but less research is conducted on the effects of critical geometric parameters. In this paper, the commercial software TracePro was used to investigate the effects of some factors on a conical cavity receiver, such as the conical angle, the number of loops of the helical tube, and the distance between the focal point of the collector and the aperture. These factors affect the optical efficiency, the maximum heat flux density, and the light distribution in the conical cavity. The optical performance of the conical receiver was studied and analyzed using the Monte Carlo ray tracing method. To make a reliable simulation, the helical tube was attached to the inner wall of the cavity in the proposed model. The results showed that the amount of light rays reaching the helical tube increases with the increasing of the conical angle, while the optical efficiency decreases and the maximum heat flux density increases. The increase in the number of loops contributed to an increase in the optical efficiency and a uniform light distribution. The conical cavity receiver had an optimal optical performance when the focal point of the collector was near the aperture.

关键词: parabolic collector     conical cavity receiver     critical geometric parameters     optical performance    

Experimental investigation and design of aluminum columns with longitudinal welds

Yun WU, Qilin ZHANG

《结构与土木工程前沿(英文)》 2011年 第5卷 第3期   页码 366-373 doi: 10.1007/s11709-011-0101-2

摘要: This paper presents an experimental investigation of longitudinally welded aluminum alloy I-section columns subjected to pure axial compression. The specimens were fabricated using 6061-T6 heat-treated aluminum alloy. The test program included 20 column tests which were separated into 2 test series of different types of welding sections. Each test series contained 10 columns. All the specimens were welded using the Tungsten Inert Gas welding method. The length of the specimens ranged from 442 to 2433 mm in order to obtain a column curve for each test series. The observed failure mode for the column tests includes mainly flexural buckling around the minor axis and the major axis by applying support except for one column (ZP1217-1) which buckled in the local zone and some columns which failed in the weld. The test strengths were compared with the design strengths predicted by the European Code and China Code for aluminum structures. The purpose of this paper is to present the tests results of two typically longitudinally welded I-section columns, and to check the accuracy of the design rules in the current specifications.

关键词: aluminum alloy     longitudinal weld     heat-affected zone (HAZ)     reduced strength zone (RSZ)     buckling     column     experimental study    

Cohesive zone model-based analyses of localized leakage of segmentally lined tunnels

《结构与土木工程前沿(英文)》 2023年 第17卷 第4期   页码 503-521 doi: 10.1007/s11709-023-0927-4

摘要: This paper presents a novel approach for simulating the localized leakage behavior of segmentally lined tunnels based on a cohesive zone model. The proposed approach not only simulates localized leakage at the lining segment, but also captures the hydromechanically coupled seepage behavior at the segmental joints. It is first verified via a tunnel drainage experiment, which reveals its merits over the existing local hydraulic conductivity method. Subsequently, a parametric study is conducted to investigate the effects of the aperture size, stratum permeability, and spatial distribution of drainage holes on the leakage behavior, stratum seepage field, and leakage-induced mechanical response of the tunnel lining. The proposed approach yields more accurate results than the classical local hydraulic conductivity method. Moreover, it is both computationally efficient and stable. Localized leakage leads to reduced local ground pressure, which further induces outward deformation near the leakage point and slight inward deformation at its diametrically opposite side. A localized stress arch spanning across the leakage point is observed, which manifests as the rotation of the principal stresses in the adjacent area. The seepage field depends on both the number and location of the leakage zones. Pseudostatic seepage zones, in which the seepage rate is significantly lower than that of the adjacent area, appear when multiple seepage zones are considered. Finally, the importance of employing the hydromechanical coupled mechanism at the segment joints is highlighted by cases of shallowly buried tunnels subjected to surface loading and pressure tunnels while considering internal water pressure.

关键词: segmentally lined tunnel     localized leakage     cohesive element     hydraulic behavior     numerical modeling    

Simulation of cottonseed cake melt flow in metering zone of a single screw extruder

Hong HE, Jianguo ZHOU,

《化学科学与工程前沿(英文)》 2010年 第4卷 第3期   页码 263-269 doi: 10.1007/s11705-009-0276-4

摘要: Research on the extrusion of natural polymers (food, feed, etc.) is relatively new due to the complex physicochemical transformations of raw materials, although plastics melt conveying and transport have been well studied. The structure and composition, rheological behavior as well as extrusion processing of natural polymer are much more complicated. In this study, a quasi-three-dimensional (3D) fluid flow model for non-Newtonian, non-isothermal and undeveloped temperature was developed, the model prediction being in reasonably good agreement with the experiment. Results show that the influence of moisture content, among other process variables, is the most significant, followed by screw speed. Some interaction exists between these two variables and the screw speed effect becomes marginal at high moisture contents. In addition, viscosity change in the channel was studied.

关键词: quasi-three-dimensional     rheological     viscosity     processing     influence    

基于粉碎区控制的钻孔爆破岩石-炸药匹配方法

冷振东,卢文波,严鹏,陈明,胡英国

《中国工程科学》 2014年 第16卷 第11期   页码 28-35

摘要:

合理的炸药-岩石匹配关系对于提高炸药能量的有效利用率和改善破碎效果有着重要意义。传统上强调的波阻抗匹配理论并不合理,文章从爆破破碎机理出发,提出了一种岩石-炸药匹配的新方法,在保证相邻炮孔间岩石充分破碎的前提下,通过对粉碎区的合理控制来确定钻孔爆破最优的炸药性能参数。该方法可以直观地反映爆破破碎效果及能量有效利用率,可操作性强。考虑相邻炮孔爆炸荷载的联合作用,修正了钻孔爆破破坏分区计算模型。在此基础上,针对具体工程目标给出了混装炸药耦合装药条件下不同等级岩石的炸药性能匹配参数。

关键词: 钻孔爆破     粉碎区     岩石-炸药匹配     波阻抗匹配    

A modified zone model for estimating equivalent room thermal capacity

Hua CHEN, Xiaolin WANG

《能源前沿(英文)》 2013年 第7卷 第3期   页码 351-357 doi: 10.1007/s11708-013-0254-x

摘要: The zone model has been widely applied in control analysis of heating, ventilation and air conditioning (HVAC) systems to achieve a high building efficiency. This paper proposed a modified zone model which is much simpler in the HVAC system simulation and has the similar accuracy to the complicated simulation model. The proposed model took into consideration the effect of envelop heat reservoir on the room indoor temperature by introducing the thermal admittance of the inner surfaces of the building enclosure. The thermal admittance for the building enclosure was developed based on the building thermal network analytical theory and transfer function method. The efficacy of the proposed model was demonstrated by comparing it with the complicated model — heat balance method (HTB2 program). The predicted results from the proposed model well agreed with those from the complicated simulation. The proposed model can then make the HVAC system dynamic simulation much faster and more acceptable for control design due to its simplicity and efficiency.

关键词: room model     thermal network analysis     transfer function     heating     ventilation and air conditioning (HVAC) system simulation    

标题 作者 时间 类型 操作

Transforming the Loess Plateau of China

Yuheng LI,Guoming DU,Yansui LIU

期刊论文

Applying the multi-zone model in predicting the operating range of HCCI engines

Ming JIA, Maozhao XIE, Zhijun PENG,

期刊论文

Microbial biodegradation of plastics: Challenges, opportunities, and a critical perspective

期刊论文

Machine learning in building energy management: A critical review and future directions

期刊论文

delamination on the stiffness of composite pipes under compressive transverse loading using cohesive zone

Sattar MALEKI, Roham RAFIEE, Abolfazl HASANNIA, Mohammad Reza HABIBAGAHI

期刊论文

Reducing environmental impacts through socioeconomic transitions: critical review and prospects

期刊论文

Advances in airborne microorganisms detection using biosensors: A critical review

期刊论文

渤海辽东带地质认识的突破与金县1-1大油田的发现

邓运华

期刊论文

effects of mismatch fracture properties in encapsulation-based self-healing concrete using cohesive-zone

Luthfi Muhammad MAULUDIN, Chahmi OUCIF, Timon RABCZUK

期刊论文

Effects of critical geometric parameters on the optical performance of a conical cavity receiver

Hu XIAO, Yanping ZHANG, Cong YOU, Chongzhe ZOU, Quentin FALCOZ

期刊论文

Experimental investigation and design of aluminum columns with longitudinal welds

Yun WU, Qilin ZHANG

期刊论文

Cohesive zone model-based analyses of localized leakage of segmentally lined tunnels

期刊论文

Simulation of cottonseed cake melt flow in metering zone of a single screw extruder

Hong HE, Jianguo ZHOU,

期刊论文

基于粉碎区控制的钻孔爆破岩石-炸药匹配方法

冷振东,卢文波,严鹏,陈明,胡英国

期刊论文

A modified zone model for estimating equivalent room thermal capacity

Hua CHEN, Xiaolin WANG

期刊论文