Search | Engineering

订阅投稿

首页工程期刊工程焦点工程成就工程前沿关于我们 English

资源类型

期刊论文 242

年份

2023 8

2022 15

2021 21

2020 11

2019 14

2018 12

2017 8

2016 7

2015 13

2014 12

2013 11

2012 12

2011 12

2010 11

2009 15

2008 11

2007 21

2006 4

2005 6

2004 2

展开︾

关键词

应力 3

应力状态 3

残余应力 3

DX桩 2

优化 2

应力波 2

强度理论 2

有限元 2

碳达峰 2

D1 turnover / photoinhibition / photoprotection / photosynthesis / tomato / xanthophyll cycle 1

GPU；密度峰值；聚类；并行计算 1

H2S应力腐蚀 1

Kaya 恒等式 1

LED灯具；加速老化测试；中位寿命；滑动平均误差 1

TC4钛合金 1

k-ε模型 1

一维应力波 1

三向受力状态 1

三塔悬索桥 1

展开︾

检索范围：

排序：展示方式：

Investigating peak stresses in fitting and repair patches of buried polyethylene gas pipes

Reza KHADEMI ZAHEDI, Pouyan ALIMOURI, Hooman KHADEMI ZAHEDI, Mohammad SHISHESAZ

《结构与土木工程前沿（英文）》 2020年第14卷第1期页码 147-168 doi: 10.1007/s11709-019-0587-6

摘要： Nowadays, polyethylene composes a large number of natural gas distribution pipelines installed under the ground. The focus of the present contribution is two fold. One of the objectives is to investigate the applicability of polyethylene fittings in joining polyethylene gas pipes which are electrofused onto the pipe ends and buried under the ground, by estimating stress distribution using finite element method. The second objective is to study the effectiveness of polyethylene repair patches which are used to mend the defected pipelines by performing a finite element analysis to calculate peak stress values. Buried polyethylene pipelines in the natural gas industry, can be imposed by sever loadings including the soil-structure interaction, traffic load, soil’s column weight, internal pressure, and thermal loads resulting from daily and/or seasonal temperature changes. Additionally, due to the application of pipe joints, and repair patches local stresses superimposed on the aforementioned loading effects. The pipe is assumed to be made of PE80 resin and its jointing socket, and the repair patch is PE100 material. The computational analysis of stresses and the computer simulations are performed using ANSYS commercial software. According to the results, the peak stress values take place in the middle of the fitting and at its internal surface. The maximum stress values in fitting and pipe are below the allowable stresses which shows the proper use of introduced fitting is applicable even in hot climate areas of Ahvaz, Iran. Although the buried pipe is imposed to the maximum values of stresses, the PE100 socket is more sensitive to a temperature drop. Furthermore, all four studied patch arrangements show significant reinforcing effects on the defected section of the buried PE gas pipe to transfer applied loads. Meanwhile, the defected buried medium density polyethylene gas pipe and its saddle fused patch can resist the imposed mechanical and thermal loads of 22°C temperature increase. Moreover, increasing the saddle fusion patch length to 12 inches reduces the maximum stress values in the pipe, significantly.

关键词： Ansys software polyethylene buried pipelines polyethylene joints polyethylene patches peak von Mises stress soil-pipe interaction temperature variation

HTML PDF 收藏

Transient analysis of thermoelastic contact problem of disk brakes

Ali BELHOCINE, Mostefa BOUCHETARA

《机械工程前沿（英文）》 2013年第8卷第2期页码 150-159 doi: 10.1007/s11465-013-0266-6

摘要：

The main purpose of this study is to analyze the thermomechanical behavior of the dry contact between the brake disk and pads during the braking phase. The simulation strategy is based on computer code ANSYS11. The modeling of transient temperature in the disk is actually used to identify the factor of geometric design of the disk to install the ventilation system in vehicles. The thermal-structural analysis is then used with coupling to determine the deformation established and the Von Mises stresses in the disk, the contact pressure distribution in pads. The results are satisfactory compared to those found in the literature.

关键词： brake disks heat flux heat-transfer coefficient Von Mises stress contact pressure

HTML PDF 收藏

Adaptive selective ES-FEM limit analysis of cracked plane-strain structures

H. NGUYEN-XUAN,T. RABCZUK

《结构与土木工程前沿（英文）》 2015年第9卷第4期页码 478-490 doi: 10.1007/s11709-015-0317-7

摘要： This paper presents a simple and efficient approach for predicting the plastic limit loads in cracked plane-strain structures. We use two levels of mesh repartitioning for the finite element limit analysis. The master level handles an adaptive primal-mesh process through a dissipation-based indicator. The slave level performs the subdivision of each triangle into three sub-triangles and constitutes a dual mesh from a pair of two adjacent sub-triangles shared by common edges of the primal mesh. Applying a strain smoothing projection to the strain rates on the dual mesh, the incompressibility constraint and the flow rule constraint are imposed over the edge-based smoothing domains and everywhere in the problem domain. The limit analysis problem is recast into the compact form of a second-order cone programming (SOCP) for the purpose of exploiting interior-point solvers. The present method retains a low number of optimization variables. It offers a convenient way for designing and solving the large-scale optimization problems effectively. Several benchmark examples are given to show the simplicity and effectiveness of the present method.

关键词： cracked structure limit analysis von Mises criterion edge-based strain smoothing second-order cone programming adaptive

HTML PDF 收藏

Damage-constitutive model for seawater coral concrete using different stirrup confinements subjected to axial loading

《结构与土木工程前沿（英文）》 2023年第17卷第3期页码 429-447 doi: 10.1007/s11709-022-0913-2

摘要： Recently, the application of detrital coral as an alternative to natural aggregates in marine structures has attracted increased attention. In this study, research on the compressive performance of coral aggregate concrete (CAC) confined using steel stirrups with anti-rust treatment was experimentally conducted. A total of 45 specimens were cast, including 9 specimens without stirrups and under different strength grades (C20, C30, and C40) and 36 specimens under different strength grades (C20, C30, and C40). Moreover, three stirrup levels (rectangular, diamond-shaped compound, and spiral stirrups) and different stirrup spacings (40, 50, 60, and 70 mm) were used. Subsequently, the stress−strain curves of specimens subjected to axial loading were measured. The effects of the stirrup spacing and stirrup configurations on the stress and strain were investigated, respectively, and the lateral effective stress of the different stirrups was calculated based on the cohesive-elastic ring model and modified elastic beam theory. Moreover, a damage-constitutive model of CAC considering the lateral stress was set up based on damage mechanics theory. The results indicated an increase in the stress and strain with a decrease in the stirrup spacing, and the adopted stirrup ratio had a better strengthening effect than the different concrete grades, and the variation in the deformation was restricted by the performance of coral coarse aggregate (CA). However, an increment in the lateral strain was observed with an increase in the axial strain. The lateral stress model showed a good agreement with the experimental data, and the proposed damage-constitutive model had a good correlation with the measured stress−strain curves.

关键词： coral aggregate concrete stress−strain curves lateral effective stress peak stress axial−lateral curves damage-constitutive model.

HTML PDF 收藏

Epidemiological study of a von Hippel-Lindau family in northwest China

null

《医学前沿（英文）》 2013年第7卷第3期页码 378-385 doi: 10.1007/s11684-013-0276-0

摘要：

von Hippel-Lindau (VHL) disease is a rare, inherited neoplastic disease characterized by hemangioblastomas (HBL) of the central nervous system (CNS), retinal angiomas, renal cell carcinomas (RCC), pancreatic endocrine tumors (PETs), pheochromocytomas, paragangliomas, and visceral cysts. We encountered a large VHL family in northwest China and conducted a systematic screening of the family members based on their epidemiological and clinical characteristics. A self-designed questionnaire was used to collect the general sociodemographic and health information of the family members. For the preliminary family screening, physical examination and abdomen B ultrasonography were performed. The suspected patients were subjected to cranial computerized tomography and fundus examination. The clinical data of the patients with confirmed VHL disease were collected from hospital records. A total of 63 lineal descendants in six generations were observed in the family (generations O, A, B, C, D, E), including 9 dead suspected cases (6 males, 3 females) and 10 living cases (2 males, 8 females). Among the 10 living cases, 4, 2, 1, 3, 4, 8, and 2 manifested HBLs of the CNS, PETs, RCC, pancreatic cysts, renal cysts, pheochromocytomas (4 hemi and 4 bilateral), and paragangliomas, respectively. Data showed that the morbidity of VHL disease in generation C was lower than that in generation B, but the age of onset was younger. This study is the first to report VHL disease in northwest China and VHL-associated PET cases in Chinese. Therefore, follow-up checkups of the family should be focused on younger generations. Proper family screening protocols should be followed for the treatment of patients with VHL disease.

关键词： von Hippel-Lindau disease epidemiology family screening pancreatic endocrine tumor

HTML PDF 收藏

Elasto-plastic fatigue crack growth analysis of plane problems in the presence of flaws using XFEM

Sachin KUMAR,A. S. SHEDBALE,I. V. SINGH,B. K. MISHRA

《结构与土木工程前沿（英文）》 2015年第9卷第4期页码 420-440 doi: 10.1007/s11709-015-0305-y

摘要： In this paper, elasto-plastic XFEM simulations have been performed to evaluate the fatigue life of plane crack problems in the presence of various defects. The stress-strain response of the material is modeled by Ramberg-Osgood equation. The von-Mises failure criterion has been used with isotropic hardening. The -integral for two fracture modes (mode-I and mode-II) is obtained by decomposing the displacement and stress fields into their symmetric and antisymmetric parts, then individual stress intensity factors are extracted from -integral. The fatigue life obtained by EPFM is found quite close to that obtained by LEFM.

关键词： XFEM von-Mises yield criterion isotropic hardening fatigue crack growth J-integral

HTML PDF 收藏

Factors influencing peak bone mass gain

Xiaowei Zhu, Houfeng Zheng

《医学前沿（英文）》 2021年第15卷第1期页码 53-69 doi: 10.1007/s11684-020-0748-y

摘要： Bone mass is a key determinant of osteoporosis and fragility fractures. Epidemiologic studies have shown that a 10% increase in peak bone mass (PBM) at the population level reduces the risk of fracture later in life by 50%. Low PBM is possibly due to the bone loss caused by various conditions or processes that occur during adolescence and young adulthood. Race, gender, and family history (genetics) are responsible for the majority of PBM, but other factors, such as physical activity, calcium and vitamin D intake, weight, smoking and alcohol consumption, socioeconomic status, age at menarche, and other secondary causes (diseases and medications), play important roles in PBM gain during childhood and adolescence. Hence, the optimization of lifestyle factors that affect PBM and bone strength is an important strategy to maximize PBM among adolescents and young people, and thus to reduce the low bone mass or osteoporosis risk in later life. This review aims to summarize the available evidence for the common but important factors that influence bone mass gain during growth and development and discuss the advances of developing high PBM.

关键词： peak bone mass children adolescents genetic risk factors

HTML PDF 收藏

The carbon dioxide removal potential of Liquid Air Energy Storage: A high-level technical and economic appraisal

Andrew LOCKLEY, Ted von HIPPEL

《工程管理前沿（英文）》 2021年第8卷第3期页码 456-464 doi: 10.1007/s42524-020-0102-8

摘要： Liquid Air Energy Storage (LAES) is at pilot scale. Air cooling and liquefaction stores energy; reheating revaporises the air at pressure, powering a turbine or engine (Ameel et al., 2013). Liquefaction requires water & CO removal, preventing ice fouling. This paper proposes subsequent geological storage of this CO – offering a novel Carbon Dioxide Removal (CDR) by-product, for the energy storage industry. It additionally assesses the scale constraint and economic opportunity offered by implementing this CDR approach. Similarly, established Compressed Air Energy Storage (CAES) uses air compression and subsequent expansion. CAES could also add CO scrubbing and subsequent storage, at extra cost. CAES stores fewer joules per kilogram of air than LAES – potentially scrubbing more CO per joule stored. Operational LAES/CAES technologies cannot offer full-scale CDR this century (Stocker et al., 2014), yet they could offer around 4% of projected CO disposals for LAES and<25% for current-technology CAES. LAES CDR could reach trillion-dollar scale this century (20 billion USD/year, to first order). A larger, less certain commercial CDR opportunity exists for modified conventional CAES, due to additional equipment requirements. CDR may be commercially critical for LAES/CAES usage growth, and the necessary infrastructure may influence plant scaling and placement. A suggested design for low-pressure CAES theoretically offers global-scale CDR potential within a century (ignoring siting constraints) – but this must be costed against competing CDR and energy storage technologies.

关键词： carbon dioxide removal Liquid Air Energy Storage Compressed Air Energy Storage geoengineering

HTML PDF 收藏

The epidemiology of norovirus gastroenteritis in China: disease burden and distribution of genotypes

Honglu Zhou, Songmei Wang, Lorenz von Seidlein, Xuanyi Wang

《医学前沿（英文）》 2020年第14卷第1期页码 1-7 doi: 10.1007/s11684-019-0733-5

摘要： With the improvements of sanitation and nationwide safe water supply the occurrence of bacterial diarrhea declined remarkably, while viruses became the leading causes of acute gastroenteritis (AGE). Of these viruses, noroviruses (NoVs) are responsible for a considerable burden of gastroenteritis, especially in children<2 years and elderly≥65 years. NoVs circulating in the Chinese population are antigenically highly diverse with the genotype GII.4 being the dominant strain followed by GII.3. Given the widespread contamination in environmental sources, and highly infectious nature of NoVs, vaccination would be the desirable strategy for the control of NoV infections. However, a better understanding of acquired immunity after infection, and a reliable immunological surrogate marker are urgently needed, since two vaccine candidates based on virus-like particles (VLPs) are currently moving into clinical evaluations in China.

关键词： molecular epidemiology norovirus disease burden genotype China

HTML PDF 收藏

Zero increase in peak discharge for sustainable development

Xing Fang, Junqi Li, Yongwei Gong, Xiaoning Li

《环境科学与工程前沿（英文）》 2017年第11卷第4期 doi: 10.1007/s11783-017-0935-5

摘要： For urban land development, some or all natural land uses (primarily pervious) are converted into impervious areas which lead to increases of runoff volume and peak discharge. Most of the developed countries require a zero increase in peak discharge for any land development, and the policy has been implemented for several decades. The policy of zero increase in peak discharge can be considered as historical and early stage for the low impact development (LID) and sustainable development, which is to maintain natural hydrological conditions by storing a part or all of additional runoff due to the development on site. The paper will discuss the policy, the policy implementation for individual projects and their impact on regional hydrology. The design rainfalls for sizing LID facilities that are determined in 206 weather stations in USA are smaller than design rainfalls for sizing detention basins. The zero-increase policy links to financial responsibility and sustainability for construction of urban stormwater infrastructures and for reducing urban flooding. The policy was compared with current practices of urban development in China to shine the light for solving urban stormwater problems. The connections and differences among LID practices, the zero-increase policy, and the flood control infrastructure were discussed. We promote and advocate the zero-increase policy on peak discharge for comprehensive stormwater management in China in addition to LID.

关键词： Stormwater management Detention basin Zero increase Peak discharge Sustainable development Design rainfall

HTML PDF 收藏

Control of peak pressures of an HCCI engine under varying swirl and operating parameters

T. KARTHIKEYA SHARMA,G. AMBA PRASAD RAO,K. MADHU MURTHY

《能源前沿（英文）》 2016年第10卷第3期页码 337-346 doi: 10.1007/s11708-016-0401-2

摘要： The major advantages of homogeneous charge compression ignition (HCCI) are high efficiency in combination with low NO -emissions. However, one of the major challenges with HCCI is the control of higher peak pressures which may damage the engine, limiting the HCCI engine life period. In this paper, an attempt is made to analyze computationally the effect of induction swirl in controlling the peak pressures of an HCCI engine under various operating parameters. A single cylinder 1.6 L reentrant piston bowl diesel engine is chosen. For computational analysis, the ECFM-3Z model of STAR –CD is considered because it is suitable for analyzing the combustion processes in SI and CI engines. As an HCCI engine is a hybrid version of SI and CI engines, the ECFM-3Z model with necessary modifications is used to analyze the peak pressures inside the combustion chamber. The ECFM-3Z model for HCCI mode of combustion is validated with the existing literature to make sure that the results obtained are accurate. Numerical experiments are performed to study the effect of varying properties like speed of the engine, piston bowl geometry, exhaust gas recirculation (EGR) and equivalence ratio under different swirl ratios in controlling the peak pressures inside the combustion chamber. The results show that the swirl ratio has a considerable impact on controlling the peak pressures of HCCI engine. A reduction in peak pressures are observed with a swirl ratio of 4 because of reduced in cylinder temperatures. The combined effect of four operating parameters, i.e., the speed of the engine, piston bowl geometry, EGR, and equivalence ratio with swirl ratios suggest that lower intake temperatures, reentrant piston bowl, higher engine speeds and higher swirl ratios are favorable in controlling the peak pressures.

关键词： HCCI engine ECFM-3Z Swirl ratio peak pressures engine speed piston bowl geometry

HTML PDF 收藏

峰谷电价体制下东北输油管网日输油优化研究

崔慧,吴长春,吴江林,孙青峰

《中国工程科学》 2004年第6卷第8期页码 69-73

摘要：

东北原油长输管网是中国规模最大的地区性原油运输系统，就该管网基于峰谷电价体制下的运行现状，建立了线性规划数学模型，提出了日输油计划优化问题，并以铁秦线为例进行分析；初步揭示了峰谷电价体制下日输油计划方式的一些基本规律，表明在该体制下东北管网具有一定的节能降耗潜力。但该方式在一定程度上受到管道本身运行特性的约束，与热油管道相比它更适合于等温管道。

关键词：东北管网峰谷电价日输油优化

HTML PDF 收藏

Peak CO

Sheng ZHOU, Maosheng DUAN, Zhiyi YUAN, Xunmin OU

《能源前沿（英文）》 2020年第14卷第4期页码 740-758 doi: 10.1007/s11708-018-0558-y

摘要： This paper studies the pathways of peaking CO emissions of Dezhou city in China, by employing a bottom-up sector analysis model and considering future economic growth, the adjustment of the industrial structure, and the trend of energy intensity. Two scenarios (a business-as-usual (BAU) scenario and a CO mitigation scenario (CMS)) are set up. The results show that in the BAU scenario, the final energy consumption will peak at 25.93 million tons of coal equivalent (Mtce) (16% growth versus 2014) in 2030. In the CMS scenario, the final energy will peak in 2020 at 23.47 Mtce (9% lower versus peak in the BAU scenario). The total primary energy consumption will increase by 12% (BAU scenario) and decrease by 3% (CMS scenario) in 2030, respectively, compared to that in 2014. In the BAU scenario, CO emission will peak in 2025 at 70 million tons of carbon dioxide (MtCO ), and subsequently decrease gradually in 2030. In the CMS scenario, the peak has occurred in 2014, and 60 MtCO will be emitted in 2030. Active policies including restructuring the economy, improving energy efficiency, capping coal consumption, and using more low-carbon /carbon free fuel are recommended in Dezhou city peaked CO emission as early as possible.

关键词： carbon dioxide emission energy consumption peak CO₂ emission low-carbon transition Dezhou city China

HTML PDF 收藏

A comprehensive simulator for assessing the reliability of a photovoltaic panel peak power tracking system

Nabil KAHOUL,Mourad HOUABES,Ammar NEÇAIBIA

《能源前沿（英文）》 2015年第9卷第2期页码 170-179 doi: 10.1007/s11708-015-0353-y

摘要： When designing a maximum power point tracking (MPPT) algorithm, it is often difficult to correctly predict, before field testing, the behavior of this MPPT under varying solar irradiation on photovoltaic (PV) panels. A solution to this problem is to design a maximum power point trackers simulator of a PV system used to test MPPT algorithms. This simulator must have the same role as the MPPT card of the PV panel and thus will fully emulate the response of a real MPPT card of the PV panel. Therefore, it is a good substitute to help to test the peak power trackers of the PV system in the laboratory. This paper describes a simple peak power trackers simulator of the PV system which has a short response time thus, can be used to test MPPT algorithms under very rapid variation condition. The obtained results and the theoretical operation confirm the reliability and the superior performance of the proposed model.

关键词： photovoltaic module DC-DC converter design maximum power point tracking (MPPT) card microprocessor

HTML PDF 收藏

基于碳排放达峰约束的2030年中国能源供需模型及实证研究

陈进行

《工程（英文）》 2017年第3卷第4期页码 512-517 doi: 10.1016/J.ENG.2017.04.019

摘要：

综合考虑经济发展、技术进步、政策目标、资源禀赋、环境容量等方面因素，设计了中国能源供需模型，构建了碳排放提前达峰和既定达峰两种情景。应用模型对两种情景下的能源供需和碳排放进行了分析，结果显示：2030年前一次能源和电力需求将持续增长，电力需求增速将显著快于一次能源需求；低碳化是能源供需结构变化的基本特征，2030年前非化石能源将超过石油成为第二大能源；选择能效更高的能源消费模式和更加低碳的能源供应方式，能源消费产生的碳排放可能在2025年左右提前达峰；电源结构的低碳化是碳排放尽早达峰、降低峰值的关键因素。

关键词：碳排放达峰能源供需模型情景