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 27

年份

2023 2

2021 2

2020 1

2019 3

2018 3

2017 1

2016 1

2015 4

2013 1

2012 1

2011 1

2010 1

2009 2

2008 2

2007 1

2005 1

展开︾

关键词

Lagrangian松弛 1

McCormick包络 1

中断模型；k-可靠性；对偶；线性规划松弛；互补松弛型 1

优化运行 1

凸松弛 1

多目标优化决策模型 1

多符号差分检测；广义似然比检验；半定松弛；双向中继传输 1

大块非晶合金，模型铸造，金属材料，结构弛豫 1

工序 1

工程网络计划 1

无线信息与能量同时传输；信道状态信息；鲁棒波束形成；半定松弛；迭代次梯度 1

时间—资源权衡协调 1

模糊线性规划 1

热电联合系统 1

状态估计；克拉美罗下界；可行解追逐；半正定松弛；近线性算法；复合优化；网络攻击；坏数据检测 1

项目时间表 1

项目计划管理 1

展开︾

检索范围：

排序：展示方式：

A solution to unit commitment problem using invasive weed optimization algorithm

B. SARAVANAN, E. R. VASUDEVAN, D. P. KOTHARI

《能源前沿（英文）》 2013年第7卷第4期页码 487-494 doi: 10.1007/s11708-013-0279-1

摘要： Unit commitment (UC) is one of the most important aspect of power generation in the world today. Though, there is no method to find the exact optimized solution, there exists several meta-heuristic algorithms to determine the close to exact solution. This paper proposes a novel solution to effectively determine UC and generation cost using the technique of invasive weed optimization (IWO). The existing technique distributes the load demand among all the generating units. The method proposed here utilizes the output of UC obtained by using the Lagrangian relaxation (LR) method and calculates the required generation from only the plants that are ON discarding the OFF generator units and thereby giving a faster and more accurate response. Moreover, the results show the comparison between the LR-particle swarm optimization (PSO) and LR-IWO, and prove that the cost of generation for a 4 unit, 8 hour schedule is much less in the case of IWO when compared to PSO.

关键词： Lagrangian relaxation (LR) invasive weed optimization (IWO) economic dispatch optimization fuel cost seed fitness

HTML PDF 收藏

Microcystin-LR biodegradation by

Chengbin XIAO, Hai YAN, Junfeng WANG, Wei WEI, Jun NING, Gang PAN

《环境科学与工程前沿（英文）》 2011年第5卷第4期页码 526-532 doi: 10.1007/s11783-010-0261-7

摘要： A promising bacterial strain for biodegrading microcystin-LR (MC-LR) as the sole carbon and nitrogen source was successfully isolated from Lake Dianchi, China. The strain was identified as sp. USTB-05, which was the first isolated MCs-biodegrading sp. in China. The average biodegradation rate of MC-LR by sp. USTB-05 was 28.8 mg·L per day, which was apparently higher than those of other bacteria reported so far. The optimal temperature and pH for both strain USTB-05 growth and MC-LR biodegradation were 30°C and 7.0, respectively. The release of MC-LR from the cyanobacterial cells collected from Lake Guishui and the biodegradation of MC-LR by both strain and cell-free extract (CE) were investigated. The results indicated that MC-LR with the initial concentration of 4.0 mg·L in water was biodegraded by sp. USTB-05 within 4 d, while MC-LR with the initial concentration of 28.8 mg·L could be completely removed in 3 h by CE of sp. USTB-05 containing 350 mg·L protein. During enzymatic biodegradation of MC-LR, two intermediate metabolites and a dead-end product were observed on an HPLC chromatogram. Moreover, the similar scanning profiles of MC-LR and its metabolic products indicate that the Adda side-chain of MC-LR was kept intact in all products.

关键词： microcystin-LR(MC-LR) biodegradation Sphingopyxis sp USTB-05 cell-free extract

HTML PDF 收藏

时间—资源权衡协调问题的多目标优化决策模型

王先甲,万仲平

《中国工程科学》 2005年第7卷第2期页码 35-40

摘要：此外，在对应于资源约束的Lagrangian松弛表示式中，给出了该二人对策问题的有关特性。

关键词：项目计划管理时间—资源权衡协调多目标优化决策模型项目时间表 Lagrangian松弛

HTML PDF 收藏

Oxidation and biotoxicity assessment of microcystin-LR using different AOPs based on UV, O

Siyi Lu, Naiyu Wang, Can Wang

《环境科学与工程前沿（英文）》 2018年第12卷第3期 doi: 10.1007/s11783-018-1030-2

摘要： Microcystin-LR attracts attention due to its high toxicity, high concentration and high frequency. The removal characteristics of UV/H O and O /H O advanced oxidation processes and their individual process for MC-LR were investigated and compared in this study. Both the removal efficiencies and rates of MC-LR as well as the biotoxicity of degradation products was analyzed. Results showed that the UV/H O process and O /H O were effective methods to remove MC-LR from water, and they two performed better than UV-, O -, H O -alone processes under the same conditions. The effects of UV intensity, H O concentration and O concentration on the removal performance were explored. The synergistic effects between UV and H O , O and H O were observed. UV dosage of 1800 mJ·cm was required to remove 90% of 100 g·L MC-LR, which amount significantly decreased to 500 mJ·cm when 1.7 mg·L H O was added. 0.25 mg·L O , or 0.125 mg·L O with 1.7 mg·L H O was needed to reach 90% removal efficiency. Furthermore, the biotoxicity results about these UV/H O , O /H O and O -alone processes all present rising trends with oxidation degree of MC-LR. Biotoxicity of solution, equivalent to 0.01 mg·L Zn , raised to 0.05 mg·L Zn after UV/H O or O /H O reaction. This phenomenon may be attributed to the aldehydes and ketones with small molecular weight generated during reaction. Advice about the selection of MC-LR removal methods in real cases was provided.

关键词： Microcystin-LR Advanced oxidation processes (AOPs) Biotoxicity Synergistic effects

HTML PDF 收藏

Deformation control criterion of shield tunnel under lateral relaxation of soft soil

《结构与土木工程前沿（英文）》 2023年第17卷第5期页码 780-795 doi: 10.1007/s11709-023-0944-3

摘要： Metro shield tunnels under the lateral relaxation of soil (LRS) are susceptible to significant lateral deformations, which jeopardizes the structural safety and waterproofing. However, deformation control standards for such situations have not been clearly defined. Therefore, based on a specific case, a model test is conducted to realize the LRS of a shield tunnel in a sandy stratum to reveal its effect on segment liners. Subsequently, a deformation control criterion is established. The LRS is simulated by linearly reducing the loads applied to the lateral sides of the segment structure. During lateral unloading, the lateral earth pressure coefficient on the segment decreases almost exponentially, and the structural deformation is characterized by horizontal expansion at the arch haunches and vertical shrinkage at the arch vault and arch bottom. Based on the mechanical pattern of the segment structure and the acoustic emission, the deformation response of a segment can be classified into three stages: elastic and quasi-elastic, damage, and rapid deformation development. For a shield tunnel with a diameter of approximately 6 m and under the lateral relaxation of sandy soil, when the ellipticity of the segment is less than 2.71%, reinforcement measures are not required. However, the segment deformation must be controlled when the ellipticity is 2.71% to 3.12%; in this regard, an ellipticity of 3% can be used as a benchmark in similar engineering projects.

关键词： shield tunnel lateral relaxation of soil deformation control criterion of segment structure model test

HTML PDF 收藏

Finding buckling points for nonlinear structures by dynamic relaxation scheme

Mohammad REZAIEE-PAJAND, Hossein ESTIRI

《结构与土木工程前沿（英文）》 2020年第14卷第1期页码 23-61 doi: 10.1007/s11709-019-0549-z

摘要： Dynamic Relaxation Method (DRM) is an explicit approach for solving the simultaneous systems of equations. In this tactic, the fictitious mass and damping are added to the static governing equations, and an artificial dynamic system is constructed. By using DRM for nonlinear analysis, the structural static equilibrium path is obtained. This outcome is extremely valuable, since it leads to the behavior of structures. Among the finding related to the structural static path are the critical and buckling points for nonlinear structures. In this paper, a new way for calculating the load factor is proposed by setting the external work zero. Mixing the dynamic relaxation scheme with external work technique has not been formulated so far. In all incremental-iterative methods, the load factor increment sign should be determinated by extra calculations. This sign leads to increase or decrease of the load increment. It is worth emphasizing that sign of the load factor increment changes at the load limit points. Therefore, the sign determinations are required in the common work control methods. These disadvantages are eliminated in the proposed algorithm. In fact, the suggested load factor depends only on the Dynamic Relaxation (DR) fictitious parameters. Besides, all DR calculations are performed via vector operation. Moreover, the load factor is calculated only by one formula, and it has the same relation in the all solution processes. In contrast to the arc length techniques, which requires the sign determined, the proposed scheme does not need any sign finding. It is shown that author’s technique is quicker than the other dynamic relaxation strategies. To prove the capability and efficiency of the presented scheme, several numerical tests are performed. The results indicate that the suggested approach can trace the complex structural static paths, even in the snap-back and snap-through parts.

关键词： load factor external work dynamic relaxation static equilibrium path large displacement

HTML PDF 收藏

Nonlinear analysis of cable structures using the dynamic relaxation method

Mohammad REZAIEE-PAJAND, Mohammad MOHAMMADI-KHATAMI

《结构与土木工程前沿（英文）》 2021年第15卷第1期页码 253-274 doi: 10.1007/s11709-020-0639-y

摘要： The analysis of cable structures is one of the most challenging problems for civil and mechanical engineers. Because they have highly nonlinear behavior, it is difficult to find solutions to these problems. Thus far, different assumptions and methods have been proposed to solve such structures. The dynamic relaxation method (DRM) is an explicit procedure for analyzing these types of structures. To utilize this scheme, investigators have suggested various stiffness matrices for a cable element. In this study, the efficiency and suitability of six well-known proposed matrices are assessed using the DRM. To achieve this goal, 16 numerical examples and two criteria, namely, the number of iterations and the analysis time, are employed. Based on a comprehensive comparison, the methods are ranked according to the two criteria. The numerical findings clearly reveal the best techniques. Moreover, a variety of benchmark problems are suggested by the authors for future studies of cable structures.

关键词： nonlinear analysis cable structure stiffness matrix dynamic relaxation method

HTML PDF 收藏

Investigation of vortical flows over oscillating body using fast Lagrangian vortex method

Baoshan ZHU ,

《能源前沿（英文）》 2009年第3卷第3期页码 297-306 doi: 10.1007/s11708-009-0010-4

摘要： A computational method facilitating long-time and high-resolution unsteady vortical flows is developed with the advantages of the discrete vortex methods. Both the velocity and pressure distribution of the flow field are calculated by integral formulations in combination with a fast summation algorithm. The vorticity field is described by Lagrangian representation, which is well suited to the moving boundary. Viscosity diffusion of the vorticity is considered with the core spreading model corrected by an adaptive splitting and merging algorithm. The effectiveness of the present method is examined by comparing the numerical results of unsteady separated flows which pass a cylinder and a thin cambered blade undergoing rotational oscillations with available experimental results. Interesting results about vortex shedding patterns and lock-in characteristics are provided for the thin cambered blade.

关键词： unsteady vortical flows fast vortex method vortex shedding rotational oscillation thin cambered blade

HTML PDF 收藏

Comparison of different algicides on growth of

Naiyu Wang, Kai Wang, Can Wang

《环境科学与工程前沿（英文）》 2017年第11卷第6期 doi: 10.1007/s11783-017-0940-8

摘要： Eutrophication with a large number of commonly occurs worldwide, thereby threatening the aquatic ecosystem and human health. In this study, four kinds of algicides were tested to explore their influence on cell density and chlorophyll-a of . Results showed that aluminum silicate agent, which inhibited more than 90% cell growth compared with the control group, demonstrated the strongest inhibition effect immediately on growth. Furthermore, the production and release of microcystin (MC)-LR were investigated. Aluminum silicate, CuSO , and Emma-11 were more effective than pyrogallic acid in disrupting the cells of , thereby increasing the extracellular MC-LR concentration. Aluminum silicate caused the highest extracellular MC-LR concentration of more than 45 mg·L . Biotoxicity was also detected to evaluate the environmental risks of MC-LR release, which were related to the usages of different algicides. Extracellular MC-LR concentration mostly increased when the biotoxicity of algae solution increased. The experiments were also designed to reveal the effects of physical conditions in riverways, such as natural sunlight, aeration and benthal sludge, on MC-LR degradation. These findings indicated that UV rays in sunlight, which can achieve a MC-LR removal efficiency of more than 15%, played an important role in MC-LR degradation. Among all the physical pathways of MC-LR removal, benthal sludge adsorption presented the optimal efficiency at 20%.

关键词： Microcystis aeruginosa MC-LR release Algicides MC-LR degradation Biotoxicity

HTML PDF 收藏

Implementation of total Lagrangian formulation for the elasto-plastic analysis of plane steel frames

Bing XIA, Yuching WU, Zhanfei HUANG

《结构与土木工程前沿（英文）》 2012年第6卷第3期页码 257-266 doi: 10.1007/s11709-012-0163-9

摘要： In this paper, the co-rotational total Lagrangian forms of finite element formulations are derived to perform elasto-plastic analysis for plane steel frames that either experience increasing external loading at ambient temperature or constant external loading at elevated temperatures. Geometric nonlinearities and thermal-expansion effects are considered. A series of programs were developed based on these formulations. To verify the accuracy and efficiency of the nonlinear finite element programs, numerical benchmark tests were performed, and the results from these tests are in a good agreement with the literature. The effects of the nonlinear terms of the stiffness matrices on the computational results were investigated in detail. It was also demonstrated that the influence of geometric nonlinearities on the incremental steps of the finite element analysis for plane steel frames in the presence of fire is limited.

关键词： co-rotational total Lagrangian geometrical nonlinearity fire elasto-plastic

HTML PDF 收藏

Microcystin-LR detection based on indirect competitive enzyme-linked immunosorbent assay

SHENG Jianwu, HE Miao, YU Shaoqing, SHI Hanchang, QIAN Yi

《环境科学与工程前沿（英文）》 2007年第1卷第3期页码 329-333 doi: 10.1007/s11783-007-0056-7

摘要： Microcystins (MCs) are a group of closely related toxic cyclic heptapeptides produced by common cyanobacteria, which cause lots of accidents and threatens human health. In this paper, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was established and used to detect microcystin-LR (MC-LR) in drinking and surface waters. The concentration of coating antigen was 5 ?g/mL, the dilution of monoclonal antibody MC10E7 was 1:3 000, the dilution of enzyme tracer (goat anti-mouse IgG-peroxidase) was 1:3 000, the standard concentration of MC-LR ranged from 0.001 μg/L to 30 μg/L, and o-phenylenediamine was used as substrate. The assay showed high relativity with high performance liquid chromatography (HPLC) with a correlation coefficient of more than 99%. The relative standard deviation was less than 10%, the detection limit was achieved down to 0.01 μg/L and up to 5.1 μg/L. The quantitative detection range was from 0.03 μg/L to 3 μg/L, and the antibody had high specificity for [4-arginine] microcystins. It performed well in spite of the influence of the real samples.

关键词： o-phenylenediamine 4-arginine ic-ELISA substrate chromatography

HTML PDF 收藏

工程网络计划的LR型模糊系数线性规划方法

高朋,冯俊文

《中国工程科学》 2009年第11卷第2期页码 70-74

摘要：文章提出一种具有LR型模糊数的线性规划模型，解决了工程网络计划的时间参数估计和关键路径识别问题，并通过引入λ截集来充分描述决策者在不同情形下对工序工期估计的可信程度。

关键词：工程网络计划模糊线性规划工序

HTML PDF 收藏

A fast and accurate dynamic relaxation scheme

Mohammad REZAIEE-PAJAND, Mohammad MOHAMMADI-KHATAMI

《结构与土木工程前沿（英文）》 2019年第13卷第1期页码 176-189 doi: 10.1007/s11709-018-0486-2

摘要： Dynamic relaxation method (DRM) is one of the suitable numerical procedures for nonlinear structural analysis. Adding the fictitious inertia and damping forces to the static equation, and turning it to the dynamic system, are the basis of this technique. Proper selection of the DRM artificial factors leads to the better convergence rate and efficient solutions. This study aims to increase the numerical stability, and to decrease the analysis time. To fulfil this objective, the reduction rate of analysis error for consecutive iterations is minimized. Based on this formulation, a new time step is found for the viscous dynamic relaxation. After combining this novel relationship with the other DRM factors, various geometrical nonlinear structures, such as, trusses, frames and shells are analyzed. The obtained results verify the efficiency of authors’ scheme.

关键词： viscous dynamic relaxation time step displacement error geometric nonlinear analysis

HTML PDF 收藏

The stress relaxation of cement clinkers under high temperature

Xiufang WANG,Yiwang BAO,Xiaogen LIU,Yan QIU

《机械工程前沿（英文）》 2015年第10卷第4期页码 413-417 doi: 10.1007/s11465-015-0357-7

摘要：

The energy consumption of crushing is directly affected by the mechanical properties of cement materials. This research provides a theoretical proof for the mechanism of the stress relaxation of cement clinkers under high temperature. Compression stress relaxation under various high temperatures is discussed using a specially developed load cell, which can measure stress and displacement under high temperatures inside an autoclave. The cell shows that stress relaxation dramatically increases and that the remaining stress rapidly decreases with an increase in temperature. Mechanical experiments are conducted under various temperatures during the cooling process to study the changes in the grinding resistance of the cement clinker with temperature. The effects of high temperature on the load-displacement curve, compressive strength, and elastic modulus of cement clinkers are systematically studied. Results show that the hardening phenomenon of the clinker becomes apparent with a decrease in temperature and that post-peak behaviors manifest characteristics of the transformation from plasticity to brittleness. The elastic modulus and compressive strength of cement clinkers increase with a decrease in temperature. The elastic modulus increases greatly when the temperature is lower than 1000 °C. The compressive strength of clinkers increases by 73.4% when the temperature drops from 1100 to 800 °C.

关键词： stress relaxation high temperature cement clinker compression elastic modulus

HTML PDF 收藏

Lagrangian simulation of deposition of CO gas-solid sudden expansion flow

HUANG Dongping, DING Guoliang, QUACK Hans

《能源前沿（英文）》 2008年第2卷第2期页码 216-221 doi: 10.1007/s11708-008-0032-3

摘要： Freezing and blockage resulting from the deposition of solid CO formed because of sudden expansion of the downstream pipe during the release of CO through safety valves, will endanger the protected equipment. To overcome this problem, the characteristics of the CO gas-solid sudden expansion flow are studied by using the disperse Lagrangian model. A comparison of the calculated deposition of the solid CO with the experimental results shows that they are in reasonable agreement. The simulation results show that the size of the solid CO formed should not be in the range of 0.04–0.07 mm ( number 3.2–9.8). This can be achieved by using an appropriate flow cross section of the safety valve.

关键词： comparison gas-solid downstream blockage Lagrangian