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Novel decoupled framework for reliability-based design optimization of structures using a robust shifting technique

Mohammad Reza GHASEMI, Charles V. CAMP, Babak DIZANGIAN

《结构与土木工程前沿（英文）》 2019年第13卷第4期页码 800-820 doi: 10.1007/s11709-019-0517-7

摘要： In a reliability-based design optimization (RBDO), computation of the failure probability ( ) at all design points through the process may suitably be avoided at the early stages. Thus, to reduce extensive computations of RBDO, one could decouple the optimization and reliability analysis. The present work proposes a new methodology for such a decoupled approach that separates optimization and reliability analysis into two procedures which significantly improve the computational efficiency of the RBDO. This technique is based on the probabilistic sensitivity approach (PSA) on the shifted probability density function. Stochastic variables are separated into two groups of desired and non-desired variables. The three-phase procedure may be summarized as: Phase 1, apply deterministic design optimization based on mean values of random variables; Phase 2, move designs toward a reliable space using PSA and finding a primary reliable optimum point; Phase 3, applying an intelligent self-adaptive procedure based on cubic B-spline interpolation functions until the targeted failure probability is reached. An improved response surface method is used for computation of failure probability. The proposed RBDO approach could significantly reduce the number of analyses required to less than 10% of conventional methods. The computational efficacy of this approach is demonstrated by solving four benchmark truss design problems published in the structural optimization literature.

关键词： reliability-based design optimization trusses sensitivity analysis shifting technique cubic B-splines response surface method

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指数多项式均匀样条模型

赵颜利,平萍,刘凤玉

《中国工程科学》 2008年第10卷第7期页码 147-152

摘要：该类模型具有很多与B 样条模型相同的性质，并且增加了一个可调节的形状参数。由该模型构造的曲线，通过改变形状参数的取值，可以调整曲线接近其控制多边形的程度。

关键词：指数多项式样条函数 B样条函数形状参数

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Implicit Heaviside filter with high continuity based on suitably graded THB splines

《机械工程前沿（英文）》 2022年第17卷第1期页码 14-14 doi: 10.1007/s11465-021-0670-2

摘要： The variable density topology optimization (TO) method has been applied to various engineering fields because it can effectively and efficiently generate the conceptual design for engineering structures. However, it suffers from the problem of low continuity resulting from the discreteness of both design variables and explicit Heaviside filter. In this paper, an implicit Heaviside filter with high continuity is introduced to generate black and white designs for TO where the design space is parameterized by suitably graded truncated hierarchical B-splines (THB). In this approach, the fixed analysis mesh of isogeometric analysis is decoupled from the design mesh, whose adaptivity is implemented by truncated hierarchical B-spline subjected to an admissible requirement. Through the intrinsic local support and high continuity of THB basis, an implicit adaptively adjusted Heaviside filter is obtained to remove the checkboard patterns and generate black and white designs. Threefold advantages are attained in the proposed filter: a) The connection between analysis mesh and adaptive design mesh is easily established compared with the traditional adaptive TO method using nodal density; b) the efficiency in updating design variables is remarkably improved than the traditional implicit sensitivity filter based on B-splines under successive global refinement; and c) the generated black and white designs are preliminarily compatible with current commercial computer aided design system. Several numerical examples are used to verify the effectiveness of the proposed implicit Heaviside filter in compliance and compliant mechanism as well as heat conduction TO problems.

关键词： topology optimization truncated hierarchical B-spline isogeometric analysis black and white designs Heaviside filter

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Evaluation method of multiaxial low cycle fatigue life for cubic single crystal material

CHEN Jiping, DING Zhiping

《机械工程前沿（英文）》 2007年第2卷第3期页码 278-282 doi: 10.1007/s11465-007-0048-0

摘要： The coupling effect of normal stress and shear stress on orthotropic materials happens when applied loading deflects from the directions of the principal axes of the material coordinate system. By taking account of the coupling effects, formulas of equivalent stress and strain for cubic single crystal materials are cited. Using the equivalent strain and equivalent stress for such material and a variable k, which is introduced to express the effect of asymmetrical cyclic loading on fatigue life, a low cycle fatigue (LCF) life prediction model for such material in multiaxial stress starts is proposed. On the basis of the yield criterion and constitutive model of cubic single crystal materials, a subroutine to calculate the thermo elastic-plastic stress-strain of the material on an ANSYS platform was developed. The cyclic stress-strain of DD3 notched specimens under asymmetrical loading at 680vH was analyzed. Low cycle fatigue test data of the single crystal nickel-based superalloy are used to fit the different parameters of the power law with multiple linear regression analysis. The equivalent stress and strain for a cubic single crystal material as failure parameters have the largest correlation coefficient. A power law exists between k and the failure cycle. The model was validated with LCF test data of CMSX-2 and DD3 single crystal nickel-based superalloys. All the test data fall into the factor of 2.5 for CMSX-2 hollow cylinder specimens and 2.0 scatter band for DD3 notched specimens, respectively.

关键词： orthotropic regression analysis crystal material multiaxial prediction

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Synthesis of ordered cerium-doped cubic mesoporous silica using long-chain ionic liquid as template

YUE Hongxia, ZHAO Hongmei, LIU Longjiang, WANG Siping, Ruan Qiong, WANG Tongwen

《化学科学与工程前沿（英文）》 2008年第2卷第2期页码 135-139 doi: 10.1007/s11705-008-0031-2

摘要： The long-chain ionic liquid 1-hexadecyl-3-methylimidazolium chloride (CmimCl) was used as a template to prepare cerium-doped MCM-48 materials in basic medium by a hydrothermal synthesis procedure. The effect of the amount of Ce salt and CmimCl/Si on the synthesis were discussed in detail. This mesoporous material exhibits a pore architecture which is cubic 3 gyroid and possesses a large surface area and a narrow pore distribution. Cerium in calcined porous framework exists in the form of well-dispersed tetrahedral coordination. The CmimCl shows a high tendency toward self-aggregation that allows the formation of the cerium-doped gyroid mesostructure by using the appropriate amount of Ce salt.

关键词： mesoporous CmimCl/Si tendency mesostructure synthesis procedure

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Crystal-to-crystal transformation from the triclinic to the cubic crystal system by partial desolvation

Qianqian Guo, Irmgard Kalf, Ulli Englert

《化学科学与工程前沿（英文）》 2018年第12卷第3期页码 433-439 doi: 10.1007/s11705-018-1743-6

摘要：

Diffusion reaction of the labile building block Mg(acacCN)₂ (acacCN= 3-cyanoacetylacetonate) with silver salts leads to a series of solvated Mg/Ag bimetallic coordination polymers with composition [Mg(acacCN)₃Ag]·solvent. Despite their common stoichiometry, the topology of these polymers depends on the solvent of crystallization. The two-dimensional coordination compound [Mg(acacCN)₃Ag]·4CHCl₃ in space group P $\overset{&OverBar;}{1}$ is obtained as platelet-shaped crystals from a mixture of methanol and chloroform. When kept in the reaction mixture, these thin plates within one week convert to isometric tetrahedral crystals of the 3D network [Mg(acacCN)₃Ag]·2CHCl₃ in the cubic space group P2₁3. The transformation reaction proceeds via dissolution and recrystallization. The co-crystallized solvent molecules play an important role for stabilizing the target structure: They subtend Cl···Cl contacts and interact via non-classical C–H···O hydrogen bonds with the coordination framework. In the new cubic coordination network, both Mg(II) and Ag(I) adopt octahedral coordination, with unprecedented face-sharing by bridging O atoms of three acetylacetonato moieties. Prolonged standing of [Mg(acacCN)₃Ag]·2CHCl₃ in the reaction medium leads to further degradation, under formation of [Ag(acacCN)].

关键词： ditopic ligand substituted acetylacetone desolvation diffraction

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Synthesis and electrocatalytic property of cubic and spherical nanoparticles of cobalt platinum alloys

Xiaowei TENG, Hong YANG,

《化学科学与工程前沿（英文）》 2010年第4卷第1期页码 45-51 doi: 10.1007/s11705-009-0308-0

摘要： This paper describes the morphological control and electrocatalytic property of CoPt nanoparticles. Both cubic and spherical CoPt nanoparticles were made using cobalt carbonyl and platinum 2,4-pentanedionate under different reaction temperatures in the presence of capping reagents, which included adamantanecarboxylic acid and hexadecylamine. Effects of heterogeneous species on shape of the CoPt nanoparticles were examined by replacing cobalt carbonyl with silver acetylacetonate. Our results suggest that the formation of different shapes of CoPt particles could be attributed to the affinity between cobalt and platinum, and the effects of capping agents. The size and shape dependent electrocatalytic properties of these nanoparticles were examined based on the direct methanol oxidation reaction.

关键词： spherical 2 4-pentanedionate adamantanecarboxylic acetylacetonate electrocatalytic

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Multiobjective trajectory optimization of intelligent electro-hydraulic shovel

《机械工程前沿（英文）》 2022年第17卷第4期 doi: 10.1007/s11465-022-0706-2

摘要： Multiobjective trajectory planning is still face challenges due to certain practical requirements and multiple contradicting objectives optimized simultaneously. In this paper, a multiobjective trajectory optimization approach that sets energy consumption, execution time, and excavation volume as the objective functions is presented for the electro-hydraulic shovel (EHS). The proposed cubic polynomial S-curve is employed to plan the crowd and hoist speed of EHS. Then, a novel hybrid constrained multiobjective evolutionary algorithm based on decomposition is proposed to deal with this constrained multiobjective optimization problem. The normalization of objectives is introduced to minimize the unfavorable effect of orders of magnitude. A novel hybrid constraint handling approach based on -constraint and the adaptive penalty function method is utilized to discover infeasible solution information and improve population diversity. Finally, the entropy weight technique for order preference by similarity to an ideal solution method is used to select the most satisfied solution from the Pareto optimal set. The performance of the proposed strategy is validated and analyzed by a series of simulation and experimental studies. Results show that the proposed approach can provide the high-quality Pareto optimal solutions and outperforms other trajectory optimization schemes investigated in this article.

关键词： trajectory planning electro-hydraulic shovel cubic polynomial S-curve multiobjective optimization entropy weight technique

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水泥砂浆立方体抗压强度尺寸效应的试验研究

苏捷,方志

《中国工程科学》 2014年第16卷第2期页码 88-92

摘要：

通过36 组强度等级分别为M30、M50 和M80 且边长分别为70 mm、100 mm、150 mm和200 mm的水泥砂浆立方体试件的抗压试验，研究了不同强度等级水泥砂浆试件抗压强度的尺寸效应，建立了强度等级与抗压强度尺寸效应的关系，提出了水泥砂浆抗压强度尺寸效应率的计算公式，通过试验数据验证了该公式的适用性。

关键词：水泥砂浆尺寸效应强度等级立方体抗压强度

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Current hepatitis B treatment guidelines and future research directions

null

《医学前沿（英文）》 2014年第8卷第2期页码 145-157 doi: 10.1007/s11684-014-0335-1

摘要：

Hepatitis B virus (HBV) infection causes a tremendous clinical burden across the world with more than half a million people dying annually from HBV related disease. Significant advances have been made in HBV treatment in the past decade and several guidelines have been published by professional societies and expert panels. Although these recommendations have been valuable to help optimize HBV treatment, there is discordance in treatment criteria and many patients infected with HBV may fall outside of these recommendations. This paper systematically reviews the natural history of the disease and compares and contrasts the recommendations for initiation of treatment from the various societies. There is also discussion of special groups that require particular consideration and some of the open research questions and future research directions within the field.

关键词： chronic hepatitis B HBV treatment guidelines APASL guidelines EASL guidelines AASLD guidelines

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Clinical characteristics and risk factors of COVID-19 patients with chronic hepatitis B: a multi-center

《医学前沿（英文）》 2022年第16卷第1期页码 111-125 doi: 10.1007/s11684-021-0854-5

摘要： The coronavirus disease 2019 (COVID-19) has spread globally. Although mixed liver impairment has been reported in COVID-19 patients, the association of liver injury caused by specific subtype especially chronic hepatitis B (CHB) with COVID-19 has not been elucidated. In this multi-center, retrospective, and observational cohort study, 109 CHB and 327 non-CHB patients with COVID-19 were propensity score matched at an approximate ratio of 3:1 on the basis of age, sex, and comorbidities. Demographic characteristics, laboratory examinations, disease severity, and clinical outcomes were compared. Furthermore, univariable and multivariable logistic and Cox regression models were used to explore the risk factors for disease severity and mortality, respectively. A higher proportion of CHB patients (30 of 109 (27.52%)) developed into severe status than non-CHB patients (17 of 327 (5.20%)). In addition to previously reported liver impairment markers, such as alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and total bilirubin, we identified several novel risk factors including elevated lactate dehydrogenase (≥245 U/L, hazard ratio (HR) = 8.639, 95% confidence interval (CI) = 2.528–29.523; P <0.001) and coagulation-related biomarker D-dimer (≥0.5 μg/mL, HR= 4.321, 95% CI= 1.443–12.939; P = 0.009) and decreased albumin (<35 g/L, HR= 0.131, 95% CI= 0.048–0.361; P <0.001) and albumin/globulin ratio (<1.5, HR= 0.123, 95% CI= 0.017–0.918; P = 0.041). In conclusion, COVID-19 patients with CHB were more likely to develop into severe illness and die. The risk factors that we identified may be helpful for early clinical surveillance of critical progression.

关键词： COVID-19 chronic hepatitis B liver injury coagulation dysfunction

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Vaccine therapies for chronic hepatitis B: can we go further?

null

《医学前沿（英文）》 2014年第8卷第1期页码 17-23 doi: 10.1007/s11684-014-0313-7

摘要：

Chronic hepatitis B is a major health burden worldwide. In addition to the recent progress in antiviral treatment, therapeutic vaccination is a promising new strategy for the control of chronic hepatitis B. On the basis of the major specific and non-specific immune dysregulations and defects in chronic hepatitis B patients, this paper presents the peptide and protein-based, DNA-based, cell-based, and antigen-antibody-based therapeutic vaccines, which have undergone clinical trials. The advantages, disadvantages, and future perspectives for these therapeutic vaccines are discussed.

关键词： chronic hepatitis B therapeutic antigen-antibody complexes DNA vaccine

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Chronic hepatitis B virus infection: epidemiology, prevention, and treatment in China

null

《医学前沿（英文）》 2014年第8卷第2期页码 135-144 doi: 10.1007/s11684-014-0331-5

摘要：

Chronic hepatitis B is a major health problem in China. The universal vaccination program since 1992 has changed the epidemiology of hepatitis B virus infection in China from highly to moderately endemic. The most prevalent hepatitis B virus strains in China are genotypes B and C, whereas those in western provinces are genotypes D and C/D hybrid. Chronic hepatitis B poses a heavy burden to the society in China. Different treatment strategies have been explored to improve patient outcomes in a cost-effective manner. However, antiviral drugs with a low genetic barrier to resistance are still extensively used because of the generally low income and limited resources in China. Individualized antiviral therapy is closely associated with translational medicine, which utilizes information from studies on genomics, immune biomarkers, and fibrosis. The results of these studies are crucial in further improving treatment outcomes.

关键词： chronic hepatitis B epidemiology prevention treatment

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基于PFM的B级钢侧架耐久性分析

李伟,李强,王平

《中国工程科学》 2011年第13卷第1期页码 56-61

摘要：

基于概率断裂力学对B级钢货车侧架的圆角细节进行了模拟耐久性试验研究，提出了一种新的通用当量初始缺陷尺寸分布的计算方法，建立了裂纹超越概率模型

关键词：耐久性疲劳 B级钢裂纹

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Impact analysis of compressor rotor blades of an aircraft engine

Y B SUDHIR SASTRY, B G KIROS, F HAILU, P R BUDARAPU

《结构与土木工程前沿（英文）》 2019年第13卷第3期页码 505-514 doi: 10.1007/s11709-018-0493-3

摘要： Frequent failures due to foreign particle impacts are observed in compressor blades of the interceptor fighter MIG-23 aircraft engines in the Ethiopian air force, supplied by the Dejen Aviation Industry. In this paper, we made an attempt to identify the causes of failure and hence recommend the suitable materials to withstand the foreign particle impacts. Modal and stress analysis of one of the recently failed MIG-23 gas turbine compressor blades made up of the following Aluminum based alloys: 6061-T6, 7075-T6, and 2024-T4, has been performed, apart from the impact analysis of the rotor blades hit by a granite stone. The numerical results are correlated to the practical observations. Based on the modal, stress and impact analysis and the material properties of the three considered alloys, alloy 7075-T6 has been recommended as the blade material.

关键词： axial flow compressor rotor and stator blades aircraft engine stress and impact analysis aluminum alloys