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Floating production storage and offloading systems’ cost and motion performance: A systems thinking application

Rini NISHANTH, Andrew WHYTE, V. John KURIAN

《工程管理前沿(英文)》 2018年 第5卷 第3期   页码 357-368 doi: 10.15302/J-FEM-2018022

摘要:

Floating production storage and offloading (FPSO) units increasingly represent a practical and economic means for deep-water oil extraction and production. Systems thinking gives a unique opportunity to seek a balance between FPSO technical performance(s), with whole-cost; stakeholder decision-making is charged to align different fit-for-use design specification options’ that address technical-motion(s), with respective life-cycle cost analyses (LCCA). Soft system methodology allows situation based analyses over set periods-of-time by diagnosing the problem-at-hand; namely, assessing the antecedents of life-cycle cost relative to FPSO sub-component design alternatives. Alternative mooring- component comparisons for either new-build hulls or refurbished hulls represent an initial necessary consideration to facilitate extraction, production and storage of deep-water oil reserves. Coupled dynamic analysis has been performed to generate FPSO motion in six degrees of freedom using SESAM DeepC, while life-cycle cost analysis (LCAA) studies give net-present-value comparisons reflective of market conditions. A parametric study has been conducted by varying wave heights from 4 – 8 m to understand FPSO motion behavior in the presence of wind and current, as well as comparing the motions of turreted versus spread mooring design alternatives. LCCA data has been generated to compare the cost of such different mooring options/hull conditions over 10 and 25-year periods. Systems thinking has been used to explain the interaction of problem variables; resultantly this paper is able to identify explicit factors affecting the choice of FPSO configurations in terms of motion and whole-cost, toward assisting significantly with the front-end engineering design (FEED) phase of fit-for-purpose configured FPSOs, in waters off Malaysia and Australia.

关键词: FPSO     LCCA     spread/turret-mooring     DeepC     cost     motion     soft-systems    

Rethinking the tendering frameworks of construction contractors in the context of a soft systems methodology

Stephen URQUHART, Andrew WHYTE

《工程管理前沿(英文)》 2018年 第5卷 第3期   页码 369-380 doi: 10.15302/J-FEM-2018019

摘要:

Limited research has been conducted on the internal tendering procedures (ITP) of construction contractors because of the commercially sensitive and confidential nature of the subject matter. This limitation explains the reluctance of contractors to undergo interviews. Existing research (outside bid/no-bid and margin decision factor identification and subsequent decision modeling development) only begins to provide insights into key tendering stages, particularly around risk assessments and corporate review processes. Early research suggested one to three review stages. However, when considering the whole work procurement process from prospect identification to contract execution, five to seven series of reviews can be arguably applied by some contractors, wherein some reviews stepped through several layers of internal senior management. Tendering processes were presented as flowchart models that traditionally follow “hard” system (rectangular shapes and straight line arrows) steps, which suggest that a precise process also leads to precise results. However, given that contractors do not win every tender they submit, the process is less precise than that suggested in rigidly structured flowcharts. Twenty-five detailed semi-structured interviews were held with purposely selected high-profile publicly and privately owned construction companies in Australia with significantly varied turnovers. Analyses show that contractors are concerned about the negative effects of increasing corporate governance demands, with many stating that people involved are the most critical element to tendering success. A new way of presenting the ITP of contractors is assessed using a soft systems methodology (SSM) approach. SSM offers an alternative way of considering human interaction challenges within the ITP of contractors, which needs to be tested with the industry. The format graphics of SSM guidelines are presented as a way of offering contractors a different approach, which may assist individuals who are looking to re-structure their tendering activities in a more humanistic and less rigid procedural approach.

关键词: contractor     corporate governance     humanistic     risk     soft systems methodology     tendering procedures    

Predication of discharge coefficient of cylindrical weir-gate using adaptive neuro fuzzy inference systems

Abbas PARSAIE,Amir Hamzeh HAGHIABI,Mojtaba SANEIE,Hasan TORABI

《结构与土木工程前沿(英文)》 2017年 第11卷 第1期   页码 111-122 doi: 10.1007/s11709-016-0354-x

摘要: Settlement of sediments behind weirs and accumulation of materials floating on water behind gates decreases the performance of these structures. Weir-gate is a combination of weir and gate structures which solves them Infirmities. Proposing a circular shape for crest of weirs to improve their performance, investigators have proposed cylindrical shape to improve the performance of weir-gate structure and call it cylindrical weir-gate. In this research, discharge coefficient of weir-gate was predicated using adaptive neuro fuzzy inference systems (ANFIS). To compare the performance of ANFIS with other types of soft computing techniques, multilayer perceptron neural network (MLP) was prepared as well. Results of MLP and ANFIS showed that both models have high ability for modeling and predicting discharge coefficient; however, ANFIS is a bit more accurate. The sensitivity analysis of MLP and ANFIS showed that Froude number of flow at upstream of weir and ratio of gate opening height to the diameter of weir are the most effective parameters on discharge coefficient.

关键词: weir-gate     soft computing     crest geometry     circular crest weir     cylindrical shape    

Development of soft kernel durum wheat

Craig F. MORRIS

《农业科学与工程前沿(英文)》 2019年 第6卷 第3期   页码 273-278 doi: 10.15302/J-FASE-2019259

摘要:

Kernel texture (grain hardness) is a fundamental and determining factor related to wheat ( spp.) milling, baking and flour utilization. There are three kernel texture classes in wheat: soft and hard hexaploid ( ), and very hard durum ( subsp. ). The genetic basis for these three classes lies with the Puroindoline genes. Phenotypically, the easiest means of quantifying kernel texture is with the Single Kernel Characterization System (SKCS), although other means are valid and can provide fundamental material properties. Typical SKCS values for soft wheat would be around 25 and for durum wheat≥80. Soft kernel durum wheat was created via homeologous recombination using the mutation, which facilitated the transfer of ca. 28 Mbp of 5DS that replaced ca. 21 Mbp of 5BS. The 5DS translocation contained a complete and intact locus and both puroindoline genes. Expression of the puroindoline genes in durum grain resulted in kernel texture and flour milling characteristics nearly identical to that of soft wheat, with high yields of break and straight-grade flours, which had small particle size and low starch damage. Dough water absorption was markedly reduced compared to durum flour and semolina. Dough was essentially unchanged and reflected the inherent gluten properties of the durum background. Pasta quality was essentially equal-to-or-better than pasta made from semolina. Agronomically, soft durum germplasm showed good potential with moderate grain yield and resistance to a number of fungal pathogens and insects. Future breeding efforts will no doubt further improve the quality and competitiveness of soft durum cultivars.

关键词: soft durum wheat     grain hardness     puroindolines     milling     baking     pasta     noodles    

Performance of soft-hard-soft (SHS) cement based composite subjected to blast loading with consideration

Jun WU,Xuemei LIU

《结构与土木工程前沿(英文)》 2015年 第9卷 第3期   页码 323-340 doi: 10.1007/s11709-015-0301-2

摘要: This paper presents a combined experimental and numerical study on the damage and performance of a soft-hard-soft (SHS) multi-layer cement based composite subjected to blast loading which can be used for protective structures and infrastructures to resist extreme loadings, and the composite consists of three layers of construction materials including asphalt concrete (AC) on the top, high strength concrete (HSC) in the middle, and engineered cementitious composites (ECC) at the bottom. To better characterize the material properties under dynamic loading, interface properties of the composite were investigated through direct shear test and also used to validate the interface model. Strain rate effects of the asphalt concrete were also studied and both compressive and tensile dynamic increase factor (DIF) curves were improved based on split Hopkinson pressure bar (SHPB) test. A full-scale field blast test investigated the blast behavior of the composite materials. The numerical model was established by taking into account the strain rate effect of all concrete materials. Furthermore, the interface properties were also considered into the model. The numerical simulation using nonlinear finite element software LS-DYNA agrees closely with the experimental data. Both the numerical and field blast test indicated that the SHS composite exhibited high resistance against blast loading.

关键词: high strength concrete (SHS)     engineered cementitious composite     interface     blast test     strain rate effect    

Design and modeling of a novel soft parallel robot driven by endoskeleton pneumatic artificial muscles

《机械工程前沿(英文)》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0678-2

摘要: Owing to their inherent great flexibility, good compliance, excellent adaptability, and safe interactivity, soft robots have shown great application potential. The advantages of light weight, high efficiency, non-polluting characteristic, and environmental adaptability provide pneumatic soft robots an important position in the field of soft robots. In this paper, a soft robot with 10 soft modules, comprising three uniformly distributed endoskeleton pneumatic artificial muscles, was developed. The robot can achieve flexible motion in 3D space. A novel kinematic modeling method for variable-curvature soft robots based on the minimum energy method was investigated, which can accurately and efficiently analyze forward and inverse kinematics. Experiments show that the robot can be controlled to move to the desired position based on the proposed model. The prototype and modeling method can provide a new perspective for soft robot design, modeling, and control.

关键词: pneumatic artificial muscles     soft robot     modeling approach     principle of virtual work     external load    

Risk stratification system for skin and soft tissue infections after allogeneic hematopoietic stem cell

《医学前沿(英文)》   页码 957-968 doi: 10.1007/s11684-021-0910-1

摘要: Skin and soft tissue infections (SSTIs) refer to infections involving the skin, subcutaneous tissue, fascia, and muscle. In transplant populations with hematological malignancies, an immunocompromised status and the routine use of immunosuppressants increase the risk of SSTIs greatly. However, to date, the profiles and clinical outcomes of SSTIs in hematopoietic stem cell transplantation (HSCT) patients remain unclear. This study included 228 patients (3.67%) who developed SSTIs within 180 days after allogeneic HSCT from January 2004 to December 2019 in Peking University People’s Hospital. The overall annual survival rate was 71.5%. We compared the differences between survivors and non-survivors a year after transplant and found that primary platelet graft failure (PPGF), comorbidities of acute kidney injury (AKI), and hospital-acquired pneumonia (HAP) were independent risk factors for death in the study population. A PPGF–AKI–HAP risk stratification system was established with a mortality risk score of 1×PPGF+1×AKI+1×HAP. The areas under the curves of internal and external validation were 0.833 (95% CI 0.760–0.906) and 0.826 (95% CI 0.715–0.937), respectively. The calibration plot revealed the high consistency of the estimated risks, and decision curve analysis showed considerable net benefits for patients.

关键词: skin and soft tissue infections     hematopoietic stem cell transplantation     risk stratification system     mortality    

Crack evolution of soft–hard composite layered rock-like specimens with two fissures under uniaxial compression

《结构与土木工程前沿(英文)》 2021年 第15卷 第6期   页码 1372-1389 doi: 10.1007/s11709-021-0772-2

摘要: Acoustic emission and digital image correlation were used to study the spatiotemporal evolution characteristics of crack extension of soft and hard composite laminated rock masses (SHCLRM) containing double fissures under uniaxial compression. The effects of different rock combination methods and prefabricated fissures with different orientations on mechanical properties and crack coalescence patterns were analyzed. The characteristics of the acoustic emission source location distribution, and frequency changes of the crack evolution process were also investigated. The test results show that the damage mode of SHCLRM is related to the combination mode of rock layers and the orientation of fractures. Hard layers predominantly produce tensile cracks; soft layers produce shear cracks. The first crack always sprouts at the tip or middle of prefabricated fractures in hard layers. The acoustic emission signal of SHCLRM with double fractures has clear stage characteristics, and the state of crack development can be inferred from this signal to provide early warning for rock fracture instability. This study can provide a reference for the assessment of the fracture development status between adjacent roadways in SHCLRM in underground mines, as well as in roadway layout and support.

关键词: soft−hard composite layered rock mass     double cracks     crack evolution     acoustic emission     digital image correlation    

Modular crawling robots using soft pneumatic actuators

Nianfeng WANG, Bicheng CHEN, Xiandong GE, Xianmin ZHANG, Wenbin WANG

《机械工程前沿(英文)》 2021年 第16卷 第1期   页码 163-175 doi: 10.1007/s11465-020-0605-3

摘要: Crawling robots have elicited much attention in recent years due to their stable and efficient locomotion. In this work, several crawling robots are developed using two types of soft pneumatic actuators (SPAs), namely, an axial elongation SPA and a dual bending SPA. By constraining the deformation of the elastomeric chamber, the SPAs realize their prescribed motions, and the deformations subjected to pressures are characterized with numerical models. Experiments are performed for verification, and the results show good agreement. The SPAs are fabricated by casting and developed into crawling robots with 3D-printing connectors. Control schemes are presented, and crawling tests are performed. The speeds predicted by the numerical models agree well with the speeds in the experiments.

关键词: soft robot     soft pneumatic actuator     kinematic model     crawling robot     modular design    

Seismic responses of subway station with different distributions of soft soil in Tianjin

Dejian YANG,Meiling DUAN

《结构与土木工程前沿(英文)》 2014年 第8卷 第2期   页码 187-193 doi: 10.1007/s11709-014-0252-z

摘要: In connection with the practical project of Kunming Road station of Tianjin subway Line 3, the paper established a two-dimensional finite element model with visco-elastic boundary by using ANSYS and analyzed seismic responses of subway station with different distribution of soft soil. The nonlinear dynamic properties of soft soils are modeled by the KINH. And obtain the response rules about displacement and internal force on subway station in the general field soil and five different distributions of soft soil. Provide reference for improving the seismic performance of subway stations in Tianjin soft soil.

关键词: distribution of soft soil     soft soil in Tianjin     seismic response     ANSYS    

A multiscale material model for heterogeneous liquid droplets in solid soft composites

《结构与土木工程前沿(英文)》 2021年 第15卷 第5期   页码 1292-1299 doi: 10.1007/s11709-021-0771-3

摘要: Liquid droplets in solid soft composites have been attracting increasing attention in biological applications. In contrary with conventional composites, which are made of solid elastic inclusions, available material models for composites including liquid droplets are for highly idealized configurations and do not include all material real parameters. They are also all deterministic and do not address the uncertainties arising from droplet radius, volume fraction, dispersion and agglomeration. This research revisits the available models for liquid droplets in solid soft composites and presents a multiscale computational material model to determine their elastic moduli, considering nearly all relevant uncertainties and heterogeneities at different length scales. The effects of surface tension at droplets interface, their volume fraction, size, size polydispersity and agglomeration on elastic modulus, are considered. Different micromechanical material models are incorporated into the presented computational framework. The results clearly indicate both softening and stiffening effects of liquid droplets and show that the model can precisely predict the effective properties of liquid droplets in solid soft composites.

关键词: liquid in solid     soft composite     computational modeling     multiscale model     heterogeneity    

Numerical investigation of the ultimate lateral resistance of piles in soft clay

Konstantinos P. TZIVAKOS,Michael J. KAVVADAS

《结构与土木工程前沿(英文)》 2014年 第8卷 第2期   页码 194-200 doi: 10.1007/s11709-014-0251-0

摘要: The paper presents a numerical study on the undrained lateral response of a single, free-head, reinforced concrete pile in soft clays. Soil conditions simulating normally consolidated clays are examined—undrained shear strength increasing with depth—and the pile-soil interaction under static lateral loading is analyzed. The nonlinear ? curves proposed in literature for soft clays are imported into a beam-on-nonlinear-Winkler-foundation simulation in order to predict the pile head lateral load—displacement curve and the distribution of the horizontal displacement and bending moment along the pile. The striking differences among these methods require further investigation via 3D finite element analyses. The determination of the ultimate soil resistance from the results of the finite element analyses aims at providing the estimation of a range of values for the ultimate soil resistance coefficient with depth and the comparison of the derived values to the corresponding ones proposed by existing methodologies.

关键词: laterally loaded     pile     soft clay     p?y curves     finite element method (FEM)    

Preparation and performance of soft actuator based on IPMC with silver electrodes

Qi CHEN, Ke XIONG, Kan BIAN, Ning JIN, Bangfeng WANG,

《机械工程前沿(英文)》 2009年 第4卷 第4期   页码 436-440 doi: 10.1007/s11465-009-0054-5

摘要: The surface electrodes of traditional ionic polymer-metal composites (IPMC) are made of platinum. To reduce the production cost, nonprecious metals such as silver is proposed. A new approach of electroless silver plating based on chemical deposition method is adopted, getting two types of IPMCs, Pt-Ag IPMC, and Ag-Ag IPMC. The microscopic analysis, driving abilities tests, and their surface-electrode resistance analysis show that Ag and Pt particles penetrate inside Nafion membrane with gradient distribution throughout the membrane. The maximum electro-active bending deformation angles of the specimens, which are obtained under the same specimen dimension and constrains, are about 60° for Pt-Pt IPMC and Pt-Ag IPMC and 90° for the Ag-Ag IPMC, respectively, corresponding to the driving voltage of 3 V, 4 V, and 1.5 V. The surface-electrode resistance of Ag-Ag IPMC is the lowest and the most stable, which shows that the proposed approach is valid. The experiments show that the IPMC technology based on the silver electrode is feasible.

关键词: ionic polymer-metal composites (IPMC)     Nafion     intelligent material     soft actuators     electroless silver plating    

Erratum to: Soft-HGRNs: soft hierarchical graph recurrent networks for multi-agent partially observable

Yixiang REN, Zhenhui YE, Yining CHEN, Xiaohong JIANG, Guanghua SONG

《信息与电子工程前沿(英文)》 2023年 第24卷 第3期   页码 480-480 doi: 10.1631/FITEE.22e0073

Field testing of geosynthetic-reinforced and column-supported earth platforms constructed on soft soil

Qiangong CHENG,Jiujiang WU,Dongxue ZHANG,Fengping MA

《结构与土木工程前沿(英文)》 2014年 第8卷 第2期   页码 124-139 doi: 10.1007/s11709-014-0255-9

摘要: This paper is focused on the behavior of geosynthetic-reinforced and column-supported (GRCS) earth platforms in soft soil. By analyzing the data of a 15-month long field monitoring project, the bearing behavior and effectiveness of GRCS earth platforms are discussed in detail. It can be found that the soil arching is generated when the filling reaches a certain height. The measured pressure acting on the soil in the center of four piles was smaller than that acting on the soil between two piles. The elongation and the tension of the geogrid located in the soil between piles are both larger than the corresponding values on the pile top. The skin friction of piles is relatively small in the soil layer with low strength and the load transfer of the axial force in those layers is significant; meanwhile, the opposite situation occurs in the soil layer with high strength. The pore water pressure at shallow locations increases slightly with the filling height and is greatly affected by the increasing filling load. The layered settlement is directly proportional to the filling height, and the corresponding amount is relevant to the locations and the properties of specific soil layers. Additionally, the lateral displacement of the embankment increases with greater loading and decreases with increased depth. These suggest that the use of GRCS system can reduce lateral displacements and enhance the stability of an embankment significantly.

关键词: geosynthetic-reinforced and column-supported (GRCS) earth platforms     soft soil     bearing behavior     settlement and deformation     field testing    

标题 作者 时间 类型 操作

Floating production storage and offloading systems’ cost and motion performance: A systems thinking application

Rini NISHANTH, Andrew WHYTE, V. John KURIAN

期刊论文

Rethinking the tendering frameworks of construction contractors in the context of a soft systems methodology

Stephen URQUHART, Andrew WHYTE

期刊论文

Predication of discharge coefficient of cylindrical weir-gate using adaptive neuro fuzzy inference systems

Abbas PARSAIE,Amir Hamzeh HAGHIABI,Mojtaba SANEIE,Hasan TORABI

期刊论文

Development of soft kernel durum wheat

Craig F. MORRIS

期刊论文

Performance of soft-hard-soft (SHS) cement based composite subjected to blast loading with consideration

Jun WU,Xuemei LIU

期刊论文

Design and modeling of a novel soft parallel robot driven by endoskeleton pneumatic artificial muscles

期刊论文

Risk stratification system for skin and soft tissue infections after allogeneic hematopoietic stem cell

期刊论文

Crack evolution of soft–hard composite layered rock-like specimens with two fissures under uniaxial compression

期刊论文

Modular crawling robots using soft pneumatic actuators

Nianfeng WANG, Bicheng CHEN, Xiandong GE, Xianmin ZHANG, Wenbin WANG

期刊论文

Seismic responses of subway station with different distributions of soft soil in Tianjin

Dejian YANG,Meiling DUAN

期刊论文

A multiscale material model for heterogeneous liquid droplets in solid soft composites

期刊论文

Numerical investigation of the ultimate lateral resistance of piles in soft clay

Konstantinos P. TZIVAKOS,Michael J. KAVVADAS

期刊论文

Preparation and performance of soft actuator based on IPMC with silver electrodes

Qi CHEN, Ke XIONG, Kan BIAN, Ning JIN, Bangfeng WANG,

期刊论文

Erratum to: Soft-HGRNs: soft hierarchical graph recurrent networks for multi-agent partially observable

Yixiang REN, Zhenhui YE, Yining CHEN, Xiaohong JIANG, Guanghua SONG

期刊论文

Field testing of geosynthetic-reinforced and column-supported earth platforms constructed on soft soil

Qiangong CHENG,Jiujiang WU,Dongxue ZHANG,Fengping MA

期刊论文