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Fatigue crack growth behavior of a 170 mm diameter stainless steel straight pipe subjected to combinedtorsion and bending load

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 905-913 doi: 10.1007/s11709-021-0683-2

摘要： In a nuclear powerplant, the rotary equipment, such as a pump directly fitted with hanger in the piping system, experiences torsional and bending loads. Higher crack growth rate occurs because of this torsional load in addition to the bending load. Hence, it is necessary to study the fatigue behavior of piping components under the influence of combined torsional and bending load. In this study, experimental fatigue life evaluation was conducted on a notched stainless steel SA312 Type 304LN straight pipe having an outer diameter of 170 mm. The experimental crack depth was measured using alternating current potential drop technique. The fatigue life of the stainless steel straight pipe was predicted using experiments, Delale and Erdogan method, and area-averaged root mean square–stress intensity factor approach at the deepest and surface points of the notch. Afterward, the fatigue crack growth and crack pattern were discussed. As a result, fatigue crack growth predicted using analytical methods are in good agreement with experimental results.

关键词： fatigue life     Delale and Erdogan method     RMS–SIF approach     stainless steel     torsion and bending load     fatigue crack growth    

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Multiscale mechanical modeling of hydrated cement paste under tensile load using the combined DEM-MD

Yue HOU, Linbing WANG

《结构与土木工程前沿（英文）》 2017年 第11卷 第3期   页码 270-278 doi: 10.1007/s11709-017-0408-8

摘要： In this paper, a combined DEM-MD method is proposed to simulate the crack failure process of Hydrated Cement Paste (HCP) under a tensile force. A three-dimensional (3D) multiscale mechanical model is established using the combined Discrete Element Method (DEM)-Molecular Dynamics (MD) method in LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator). In the 3D model, HCP consists of discrete particles and atoms. Simulation results show that the combined DEM-MD model is computationally efficient with good accuracy in predicting tensile failures of HCP.

关键词： hydrated cement paste     multiscale     MD simulation     DEM    

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Influence of axial load on the lateral pile groups response in cohesionless and cohesive soil

Jasim M. ABBASA,Zamri CHIK,Mohd Raihan TAHA

《结构与土木工程前沿（英文）》 2015年 第9卷 第2期   页码 176-193 doi: 10.1007/s11709-015-0289-7

摘要： The lateral response of single and group of piles under simultaneous vertical and lateral loads has been analyzed using a 3D finite element approach. The response in this assessment considered lateral pile displacement and lateral soil resistance and corresponding - curve. As a result, modified - curves for lateral single pile response were improved with respect to the influence of increasing axial load intensities. The improved plots can be used for lateral loaded pile design and to produce the group action design -multiplier curves and equations. The effect of load combination on the lateral pile group response was performed on three pile group configurations (i.e., 2×1, 2×2 and 3×2) with four pile spacings (i.e., = 2 , 4 , 6 and 8 ). As a result, design curves were developed and applied on the actual case studies and similar expected cases for assessment of pile group behavior using improved p-multiplier. A design equation was derived from predicted design curves to be used in the evaluation of the lateral pile group action taking into account the effect of axial load intensities. It was found that the group interaction effect led to reduced lateral resistance for the pile in the group relative to that for the single pile in case of pure lateral load. While, in case of simultaneous combined loads, large axial load intensities (i.e., more than 6 , where is lateral load values) will have an increase in -multiplier by approximately 100% and will consequently contribute to greater group piles capacities.

关键词： piles     pile group     spacing     configuration     combined load    

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Stormwater runoff pollution loads from an urban catchment with rainy climate in China

Liqing LI, Baoqing SHAN, Chenqing YIN

《环境科学与工程前沿（英文）》 2012年 第6卷 第5期   页码 672-677 doi: 10.1007/s11783-012-0447-2

摘要： An older urban district in Wuhan, China, is transitioning from discharging sewage and stormwater directly into lakes, to directing the sewage to wastewater treatment plants (WWTPs). Dealing with polluted stormwater discharge is a great challenge. Stormwater runoff from an urban catchment with a combined sewer system was sampled and analyzed over a three-year period. Results indicate that wet weather flows account for 66%, 31%, 17%, and 13% of the total load of suspended solids (SS), chemical oxygen demand (COD), total nitrogen, and total phosphorus, respectively. The first flush of COD and SS was significant in all runoff events. More than 50% of the SS and COD loads were transported by the first 30% of runoff volume. Storage and treatment of the first 10 mm from each combined sewer overflow event could reduce more than 70% of the annual COD overflow load. An integrated solution is recommended, consisting of a tank connected to the WWTP and a detention pond, to store and treat the combined sewer overflow (CSO). These results may be helpful in mitigating CSO pollution for many other urban areas in China and other developing countries.

关键词： combined sewer overflow     pollution load     first flush     detention basins    

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Estimation of composite load model with aggregate induction motor dynamic load for an isolated hybrid

Nitin Kumar SAXENA,Ashwani Kumar SHARMA

《能源前沿（英文）》 2015年 第9卷 第4期   页码 472-485 doi: 10.1007/s11708-015-0373-7

摘要： It is well recognized that the voltage stability of a power system is affected by the load model and hence, to effectively analyze the reactive power compensation of an isolated hybrid wind-diesel based power system, the loads need to be considered along with the generators in a transient analysis. This paper gives a detailed mathematical modeling to compute the reactive power response with small voltage perturbation for composite load. The composite load is a combination of the static and dynamic load model. To develop this composite load model, the exponential load is used as a static load model and induction motors (IMs) are used as a dynamic load model. To analyze the dynamics of IM load, the fifth, third and first order model of IM are formulated and compared using differential equations solver in Matlab coding. Since the decentralized areas have many small consumers which may consist large numbers of IMs of small rating, it is not realistic to model either a single large rating unit or all small rating IMs together that are placed in the system. In place of using a single large rating IM, a group of motors are considered and then the aggregate model of IM is developed using the law of energy conservation. This aggregate model is used as a dynamic load model. For different simulation studies, especially in the area of voltage stability with reactive power compensation of an isolated hybrid power system, the transfer function of the composite load is required. The transfer function of the composite load is derived in this paper by successive derivation for the exponential model of static load and for the fifth and third order IM dynamic load model using state space model.

关键词： isolated hybrid power system (IHPS)     composite load model     static load     dynamic load     induction motor load model     aggregate load    

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Development of combined transitional pavement structure for urban tram track-road grade crossings

《结构与土木工程前沿（英文）》   页码 1199-1210 doi: 10.1007/s11709-023-0949-y

摘要： The grade crossings and adjacent pavements of urban trams are generally subjected to complex load conditions and are susceptible to damage. Therefore, in this study, a novel pavement structure between tram tracks and roads constructed using polyurethane (PU) elastic concrete and ultra-high-performance concrete (UHPC), referred to as a track-road transitional pavement (TRTP), is proposed. Subsequently, its performance and feasibility are evaluated using experimental and numerical methods. First, the mechanical properties of the PU elastic concrete are evaluated. The performance of the proposed structure is investigated using a three-dimensional finite element model, where vehicle-induced dynamic and static loads are considered. The results show that PU elastic concrete and the proposed combined TRTP are applicable and functioned as intended. Additionally, the PU elastic concrete achieved sufficient performance. The recommended width of the TRTP is approximately 50 mm. Meanwhile, the application of UHPC under a PU elastic concrete layer significantly reduces vertical deformation. Results of numerical calculations confirmed the high structural performance and feasibility of the proposed TRTP. Finally, material performance standards are recommended to provide guidance for pavement design and the construction of tram-grade crossings in the future.

关键词： urban tram track     grade crossing     combined track-road transitional pavement     polyurethane elastic concrete     finite element method    

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Calculation method of load distribution on pipe threaded connections under tension load

Shoujun CHEN, Lianxin GAO, Qi AN

《机械工程前沿（英文）》 2011年 第6卷 第2期   页码 241-248 doi: 10.1007/s11465-011-0219-x

摘要：

This paper presents a new calculation method that can calculate the load distribution on pipe threaded connections under tension load. On the basis of elastic mechanics, the new method was developed by analyzing each thread tooth, and a new deformation and covariant equation by making a mechanics analysis on each thread tooth was obtained. Compared with the traditional method proposed by the previous references, the new deformation and covariant equation could be used to describe the relation between the previous and the next thread tooth. By applying the new method on the sample of P-110S pipe threaded connection, the obtained results show that the load on thread tooth mainly concentrates on the four or five threads engaged and the middle teeth were not utilized well to bear the loads. The model offers a new way to calculate the loads carried on the thread teeth under tension load.

关键词： load distribution     calculation method     pipe threaded connections     tension load    

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Comparison of optimal capacitor placement methods in radial distribution system with load growth andZIP load model

Veera Venkata Satya Naryana MURTY, Ashwani KUMAR

《能源前沿（英文）》 2013年 第7卷 第2期   页码 197-213 doi: 10.1007/s11708-013-0249-7

摘要： In this paper, a combined power loss sensitivity (PLS) index-based approach is proposed to determine the optimal location of the capacitors in the radial distribution system (RDS) based on the real and reactive combined loss sensitivity index, as capacitor placement not only reduces real power loss with voltage profile improvement but also reduces reactive power loss due to the reactive power compensation in the network. The results have been obtained with the existing methods of power loss index (PLI) and index vector (IV) method for comparison. Besides, the optimal placement has been obtained with the proposed method as well as existing methods and the total kVar support has been obtained. In addition, the results of net cost savings for the 10-, 34-, and 69-bus systems are obtained for comparison. Moreover, the results have been obtained for a large system of 85 buses to validate the results with combined sensitivity based approach. Furthermore, the load growth factor has been considered in the study which is essential for the planning and expansion of the existing systems, whereas the impact of the realistic load model as ZIP load model has been considered for the study of all the systems.

关键词： load growth     load models     reactive power compensation     radial distribution system     power loss index (PLI)     power loss sensitivity (PLS)     index vector (IV)    

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emissions: a comparative study of the feasibility of the hybrid renewable energy systems incorporating combined

《能源前沿（英文）》 2022年 第16卷 第2期   页码 336-356 doi: 10.1007/s11708-021-0748-x

摘要： Fuel poverty is most prevalent in North East England with 14.4% of fuel poor households in Newcastle upon Tyne. The aim of this paper was to identify a grid connected renewable energy system coupled with natural gas reciprocating combined heat and power unit, that is cost-effective and technically feasible with a potential to generate a profit from selling energy excess to the grid to help alleviate fuel poverty. The system was also aimed at low carbon emissions. Fourteen models were designed and optimized with the aid of the HOMER Pro software. Models were compared with respect to their economic, technical, and environmental performance. A solution was proposed where restrictions were placed on the size of renewable energy components. This configuration consists of 150 kW CHP, 300 kW PV cells, and 30 kW wind turbines. The renewable fraction is 5.10% and the system yields a carbon saving of 7.9% in comparison with conventional systems. The initial capital investment is $1.24 million which enables the system to have grid sales of 582689 kWh/a. A conservative calculation determined that 40% of the sales can be used to reduce the energy cost of fuel poor households by $706 per annum. This solution has the potential to eliminate fuel poverty at the site analyzed.

关键词： greenhouse gas control     low carbon target     grid connected     renewable fraction     fuel poverty     combined heat and power     HOMER Pro    

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Interaction and combined toxicity of microplastics and per- and polyfluoroalkyl substances in aquatic

《环境科学与工程前沿（英文）》 2022年 第16卷 第10期 doi: 10.1007/s11783-022-1571-2

摘要：

● Adsorption of PFASs on MPs and its mechanisms are critically reviewed.

关键词： Microplastics     Per- and Polyfluoroalkyl substances     Adsorption     Transport     Transformation    

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A practical multi-lane factor model of bridges based on multi-truck presence considering lane load disparities

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 877-894 doi: 10.1007/s11709-021-0756-2

摘要： Many bridge design specifications consider multi-lane factors (MLFs) a critical component of the traffic load model. Measured multi-lane traffic data generally exhibit significant lane disparities in traffic loads over multiple lanes. However, these disparities are not considered in current specifications. To address this drawback, a multi-coefficient MLF model was developed based on an improved probabilistic statistical approach that considers the presence of multiple trucks. The proposed MLF model and approach were calibrated and demonstrated through an example site. The model sensitivity analysis demonstrated the significant influence of lane disparity of truck traffic volume and truck weight distribution on the MLF. Using the proposed approach, the experimental site study yielded MLFs comparable with those directly calculated using traffic load effects. The exclusion of overloaded trucks caused the proposed approach, existing design specifications, and conventional approach of ignoring lane load disparity to generate comparable MLFs, while the MLFs based on the proposed approach were the most comprehensive. The inclusion of overloaded trucks caused the conventional approach and design specifications to overestimate the MLFs significantly. Finally, the benefits of the research results to bridge practitioners were discussed.

关键词： bridges     multi-lane factor     traffic load     lane load disparity     multi-truck presence     weigh-in-motion data    

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Experimental study on combined buoyant-thermocapillary flow along with rising liquid film on the surface

Manuel J. GOMES, Ning MEI

《能源前沿（英文）》 2020年 第14卷 第1期   页码 114-126 doi: 10.1007/s11708-017-0483-5

摘要： Temperature distribution and variation with time has been considered in the analysis of the influences of the initial level of immersion of a horizontal metallic mesh tube in the liquid on combined buoyant and thermo-capillary flow. The combined flow occurs along with the rising liquid film flow on the surface of a horizontal metallic mesh tube. Three different levels of immersion of the metallic mesh tube in the liquid have been tested. Experiments of 60 min in duration have been performed using a heating metallic tube with a diameter of 25 mm and a length of 110 mm, sealed outside with a metallic mesh of 178 mm by 178 mm, and distilled water. These reveal two distinct flow patterns. Thermocouples and infrared thermal imager are utilized to measure the temperature. The level of the liquid free surface relative to the lower edge of the tube is measured as angle . The results show that for a smaller angle, or a low level of immersion, with a relatively low heating power, it is possible to near fully combine the upwards buoyant flow with the rising liquid film flow. In this case, the liquid is heated only in the vicinity of the tube, while the liquid away from the flow region experiences small changes in temperature and the system approaches steady conditions. For larger angles, or higher levels of immersion, a different flow pattern is noticed on the liquid free surface and identified as the thermo-capillary (Marangoni) flow. The rising liquid film is also present. The higher levels of immersion cause a high temperature gradient in the liquid free surface region and promote thermal stratification; therefore the system could not approach steady conditions.

关键词： rising liquid film     combined flow     thermo-capillary flow     buoyant flow     metallic mesh tube     horizontal tube    

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Shape design of arch dams under load uncertainties with robust optimization

Fengjie TAN, Tom LAHMER

《结构与土木工程前沿（英文）》 2019年 第13卷 第4期   页码 852-862 doi: 10.1007/s11709-019-0522-x

摘要： Due to an increased need in hydro-electricity, water storage, and flood protection, it is assumed that a series of new dams will be build throughout the world. The focus of this paper is on the non-probabilistic-based design of new arch-type dams by applying means of robust design optimization (RDO). This type of optimization takes into account uncertainties in the loads and in the material properties of the structure. As classical procedures of probabilistic-based optimization under uncertainties, such as RDO and reliability-based design optimization (RBDO), are in general computationally expensive and rely on estimates of the system’s response variance, we will not follow a full-probabilistic approach but work with predefined confidence levels. This leads to a bi-level optimization program where the volume of the dam is optimized under the worst combination of the uncertain parameters. As a result, robust and reliable designs are obtained and the result is independent from any assumptions on stochastic properties of the random variables in the model. The optimization of an arch-type dam is realized here by a robust optimization method under load uncertainty, where hydraulic and thermal loads are considered. The load uncertainty is modeled as an ellipsoidal expression. Comparing with any traditional deterministic optimization method, which only concerns the minimum objective value and offers a solution candidate close to limit-states, the RDO method provides a robust solution against uncertainty. To reduce the computational cost, a ranking strategy and an approximation model are further involved to do a preliminary screening. By this means, the robust design can generate an improved arch dam structure that ensures both safety and serviceability during its lifetime.

关键词： arch dam     shape optimization     robust optimization     load uncertainty     approximation model    

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Simulation and experiments on a solid sorption combined cooling and power system driven by the exhaust

Peng GAO, Liwei WANG, Ruzhu WANG, Yang YU

《能源前沿（英文）》 2017年 第11卷 第4期   页码 516-526 doi: 10.1007/s11708-017-0511-5

摘要： A solid sorption combined cooling and power system driven by exhaust waste heat is proposed, which consists of a MnCl sorption bed, a CaCl sorption bed, an evaporator, a condenser, an expansion valve, and a scroll expander, and ammonia is chosen as the working fluid. First, the theoretical model of the system is established, and the partitioning calculation method is proposed for sorption beds. Next, the experimental system is established, and experimental results show that the refrigerating capacity at the refrigerating temperature of –10°C and the resorption time of 30 min is 1.95 kW, and the shaft power is 109.2 W. The system can provide approximately 60% of the power for the evaporator fan and the condenser fan. Finally, the performance of the system is compared with that of the solid sorption refrigeration system. The refrigerating capacity of two systems is almost the same at the same operational condition. Therefore, the power generation process does not influence the refrigeration process. The exergy efficiency of the two systems is 0.076 and 0.047, respectively. The feasibility of the system is determined, which proves that this system is especially suitable for the exhaust waste heat recovery.

关键词： solid sorption     exhaust waste heat     combined cooling and power system     exergy efficiency    

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Prediction of bed load sediments using different artificial neural network models

Reza ASHEGHI, Seyed Abbas HOSSEINI

《结构与土木工程前沿（英文）》 2020年 第14卷 第2期   页码 374-386 doi: 10.1007/s11709-019-0600-0

摘要： Modeling and prediction of bed loads is an important but difficult issue in river engineering. The introduced empirical equations due to restricted applicability even in similar conditions provide different accuracies with each other and measured data. In this paper, three different artificial neural networks (ANNs) including multilayer percepterons, radial based function (RBF), and generalized feed forward neural network using five dominant parameters of bed load transport formulas for the Main Fork Red River in Idaho-USA were developed. The optimum models were found through 102 data sets of flow discharge, flow velocity, water surface slopes, flow depth, and mean grain size. The deficiency of empirical equations for this river by conducted comparison between measured and predicted values was approved where the ANN models presented more consistence and closer estimation to observed data. The coefficient of determination between measured and predicted values for empirical equations varied from 0.10 to 0.21 against the 0.93 to 0.98 in ANN models. The accuracy performance of all models was evaluated and interpreted using different statistical error criteria, analytical graphs and confusion matrixes. Although the ANN models predicted compatible outputs but the RBF with 79% correct classification rate corresponding to 0.191 network error was outperform than others.

关键词： bed load prediction     artificial neural network     modeling     empirical equations    

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标题 作者 时间 类型 操作

Fatigue crack growth behavior of a 170 mm diameter stainless steel straight pipe subjected to combinedtorsion and bending load

期刊论文

Multiscale mechanical modeling of hydrated cement paste under tensile load using the combined DEM-MD

Yue HOU, Linbing WANG

期刊论文

Influence of axial load on the lateral pile groups response in cohesionless and cohesive soil

Jasim M. ABBASA,Zamri CHIK,Mohd Raihan TAHA

期刊论文

Stormwater runoff pollution loads from an urban catchment with rainy climate in China

Liqing LI, Baoqing SHAN, Chenqing YIN

期刊论文

Estimation of composite load model with aggregate induction motor dynamic load for an isolated hybrid

Nitin Kumar SAXENA,Ashwani Kumar SHARMA

期刊论文

Development of combined transitional pavement structure for urban tram track-road grade crossings

期刊论文

Calculation method of load distribution on pipe threaded connections under tension load

Shoujun CHEN, Lianxin GAO, Qi AN

期刊论文

Comparison of optimal capacitor placement methods in radial distribution system with load growth andZIP load model

Veera Venkata Satya Naryana MURTY, Ashwani KUMAR

期刊论文

emissions: a comparative study of the feasibility of the hybrid renewable energy systems incorporating combined

期刊论文

Interaction and combined toxicity of microplastics and per- and polyfluoroalkyl substances in aquatic

期刊论文

A practical multi-lane factor model of bridges based on multi-truck presence considering lane load disparities

期刊论文

Experimental study on combined buoyant-thermocapillary flow along with rising liquid film on the surface

Manuel J. GOMES, Ning MEI

期刊论文

Shape design of arch dams under load uncertainties with robust optimization

Fengjie TAN, Tom LAHMER

期刊论文

Simulation and experiments on a solid sorption combined cooling and power system driven by the exhaust

Peng GAO, Liwei WANG, Ruzhu WANG, Yang YU

期刊论文

Prediction of bed load sediments using different artificial neural network models

Reza ASHEGHI, Seyed Abbas HOSSEINI

期刊论文