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Parametric equations for notch stress concentration factors of rib–deck welds under bending loading

《结构与土木工程前沿（英文）》 2021年 第15卷 第3期   页码 595-608 doi: 10.1007/s11709-021-0720-1

摘要： The effective notch stress approach for evaluating the fatigue strength of rib–deck welds requires notch stress concentration factors obtained from complex finite element analysis. To improve the efficiency of the approach, the notch stress concentration factors for three typical fatigue-cracking modes (i.e., root–toe, root–deck, and toe–deck cracking modes) were thoroughly investigated in this study. First, we developed a model for investigating the effective notch stress in rib–deck welds. Then, we performed a parametric analysis to investigate the effects of multiple geometric parameters of a rib–deck weld on the notch stress concentration factors. On this basis, the multiple linear stepwise regression analysis was performed to obtain the optimal regression functions for predicting the notch stress concentration factors. Finally, we employed the proposed formulas in a case study. The notch stress concentration factors estimated from the developed formulas show agree well with the finite element analysis results. The results of the case study demonstrate the feasibility and reliability of the proposed formulas. It also shows that the fatigue design curve of FAT225 seems to be conservative for evaluating the fatigue strength of rib–deck welds.

关键词： notch stress concentration factor     rib–deck weld     parametric analysis     regression analysis     parametric equation    

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The formation mechanism and the influence factor of residual stress in machining

null

《机械工程前沿（英文）》 2014年 第9卷 第3期   页码 265-269 doi: 10.1007/s11465-014-0311-0

摘要：

Residual stresses generated in cutting process have important influences on workpiece performance. The paper presents a method of theoretical analysis in order to explicate the formation mechanism of residual stresses in cutting. An important conclusion is drawn that the accumulated plastic strain is the main factor which determines the nature and the magnitude of surface residual stresses in the workpiece. On the basis of the analytical model for residual stress, a series of simulations for residual stress prediction during cutting AISI 1045 steel are implemented in order to obtain the influences of cutting speed, depth of cut and tool edge radius on surface residual stress in the workpiece. And these influences are explained from the perspective of formation mechanism of residual stress in cutting. The conclusions have good applicability and can be used to guide the parameters selection in actual production.

关键词： residual stress     analytical model     strain     plastic     cutting parameter    

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以土体应力状态计算边坡安全系数的方法

王国体

《中国工程科学》 2006年 第8卷 第12期   页码 80-84

摘要：

土坡的稳定分析一直是沿着条分法的思路发展的。由于对土体应力状态条件的忽视和条分法本身的缺陷，使得条分法得到的安全系数在工程中的应用面临激烈的挑战。土体不同条件下的应力状态表现为K0效应和变化，它对坡体的安全度影响不可忽视。笔者以考虑土体应力状态为条件，应用土的库伦强度定律和摩尔-库伦准则，推导出平面土坡的安全系数计算公式，与条分法的安全系数对比结果说明这种方法具有概念明确、计算简便、定性可靠的重要特点，可以直接提供于工程应用和参考。

关键词： 侧应力系数K0     初始应力状态     稳定安全系数公式    

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Finite element analysis of stress concentrations and failure criteria in composite plates with circular

null

《机械工程前沿（英文）》 2014年 第9卷 第3期   页码 281-294 doi: 10.1007/s11465-014-0307-9

摘要：

In this study, the stress concentration factors (SCF) in cross-and-angle-ply laminated composite plates as well as in isotropic plates with single circular holes subjected to uniaxial loading is studied. A quadrilateral finite element of four-node with 32 degrees of freedom at each node, previously developed for the bending and mechanical buckling of laminated composite plates, is used to evaluate the stress distribution in laminated composite plates with central circular holes. Based up on the classical plate theory, the present finite element is a combination of a linear isoparametric membrane element and a high precision rectangular Hermitian element. The numerical results obtained by the present element compare favorably with those obtained by the analytic approaches published in literature. It is observed that the obtained results are very close to the reference results, which demonstrates the accuracy of the present element. Additionally, to determine the first ply failure (FPF) of laminated plate, several failure criterions are employed. Finally, to show the effect of ratio on the failure of plates, a number of figures are given for different fiber orientation angles.

关键词： laminated composite plates     stress concentration     geometric singularity     anisotropic effect    

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Relationship between expression of hepatocyte grow factor and apoptosis of trophoblasts in hypertensive

OUYANG Shan, ZHANG Qinghua, QIAO Fuyuan

《医学前沿（英文）》 2007年 第1卷 第4期   页码 386-389 doi: 10.1007/s11684-007-0075-6

摘要： The aim of this study was to investigate the expression of hepatocyte growth factor (HGF) and Fas in placentas of uncomplicated pregnant women and those with hypertensive disorder complicating pregnancy (HDCP), and elucidate the possible relationship between HGF and apoptosis of trophoblasts. Reverse transcription-polymerase chain reaction (RT-PCR) was undertaken to examine the concentration of HGF mRNA and Fas mRNA obtained from 34 cases of HDCP and 30 cases of uncomplicated pregnancy. The expression of HGF mRNA in mild preeclampsia, severe preeclampsia and eclampsia cases was significantly lower than that in the uncomplicated cases (0.43±0.12, 0.38±0.09, 0.19±0.17 versus 0.67±0.19, <0.05), while the expression of Fas mRNA in mild preeclampsia, severe preeclampsia and eclampisa cases was significantly higher than that in the uncomplicated cases (1.58±0.26, 2.96±0.14, 5.98±1.17 versus 1.01±0.36, <0.05). For HGF mRNA and Fas mRNA, there was no difference between gestational hypertension cases and control cases. Decreased HGF mRNA or increased Fas mRNA was found along with the progress of HDCP. Negative correlation was found between the expressions of HGF and Fas. These results indicate that HGF inhibits the apoptosis mediated by Fas, and the reduced expression of HGF in HDCP may be responsible for the apoptosis of trophoblasts.

关键词： pregnancy     concentration     possible relationship     responsible     hepatocyte    

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腐蚀环境下飞机结构疲劳寿命的分析方法

穆志韬

《中国工程科学》 2002年 第4卷 第3期   页码 68-72

摘要：

依据海军现役飞机的腐蚀环境特点及结构件腐蚀损伤深度拟合规律，采用应力场强法和局部应力应变法分别对疲劳缺口系数Kf及疲劳寿命计算模型进行了分析，提出了一种腐蚀环境下飞机结构疲劳寿命的评定方法。该方法以室温大气环境下的寿命评定结论为依据，考虑了结构件腐蚀损伤后潮湿空气、盐雾、盐雾＋SO2等环境介质对疲劳寿命的影响，并结合国产某型飞机机翼前梁缘条腐蚀损伤部位的疲劳寿命及剩余寿命估算实例进行了分析。

关键词： 飞机结构     疲劳寿命     腐蚀环境     疲劳缺口系数    

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Chidamide inhibits the NOTCH1-MYC signaling axis in T-cell acute lymphoblastic leukemia

《医学前沿（英文）》 2022年 第16卷 第3期   页码 442-458 doi: 10.1007/s11684-021-0877-y

摘要： T-cell acute lymphoblastic leukemia (T-ALL) is one of the most dangerous hematological malignancies, with high tumor heterogeneity and poor prognosis. More than 60% of T-ALL patients carry NOTCH1 gene mutations, leading to abnormal expression of downstream target genes and aberrant activation of various signaling pathways. We found that chidamide, an HDAC inhibitor, exerts an antitumor effect on T-ALL cell lines and primary cells including an anti-NOTCH1 activity. In particular, chidamide inhibits the NOTCH1-MYC signaling axis by down-regulating the level of the intracellular form of NOTCH1 (NICD1) as well as MYC, partly through their ubiquitination and degradation by the proteasome pathway. We also report here the preliminary results of our clinical trial supporting that a treatment by chidamide reduces minimal residual disease (MRD) in patients and is well tolerated. Our results highlight the effectiveness and safety of chidamide in the treatment of T-ALL patients, including those with NOTCH1 mutations and open the way to a new therapeutic strategy for these patients.

关键词： T-cell acute lymphoblastic leukemia     HDAC inhibitor     chidamide     NOTCH1     MYC     ubiquitination    

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Measurement of trimethylamine concentration and evaluation of pig meat natural quality by a spectrophotometric

Mohammod Abdul HAMID,Xi WANG,Xiangdong DING,Chuduan WANG,Xingbo ZHAO

《农业科学与工程前沿（英文）》 2014年 第1卷 第3期   页码 236-241 doi: 10.15302/J-FASE-2014034

摘要： Pig meat off-flavor is attributed to trimethylamine (TMA) concentration, and it is considered as the precursor of the fishy off-flavor problems. In this study, TMA concentrations in pig meat were determined, and the interactions with breed and gender effects were discussed. In addition, the TMA threshold for meat off-flavor and pig meat natural quality was measured in relation to meat storage and movement, and the influential factors including the pig breed and storage time were discussed. The results indicated positive effects on the precursor of the fishy off-flavor and the TMA threshold. Native breeds were found to have lower TMA concentrations than European breeds ( <0.01), and females and castrated males had significantly lower TMA concentration than males ( <0.01), The threshold concentration of TMA when meat was classed as off-flavored was 25 μg·g , and this occurred after 35–38 h of storage. The natural qualities, such as appearance, flavor, color and overall acceptable scores declined significantly after 4 days in storage ( <0.01). It is concluded that pig meat off-flavor, breed and gender were essential factors affecting flavor for meat breeding programs, and storage time is important for pig meat natural quality.

关键词： pig meat     trimethylamine (TMA)     influential factor    

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Role of Wnt and Notch signaling in regulating hair cell regeneration in the cochlea

null

《医学前沿（英文）》 2016年 第10卷 第3期   页码 237-249 doi: 10.1007/s11684-016-0464-9

摘要：

Sensory hair cells in the inner ear are responsible for sound recognition. Damage to hair cells in adult mammals causes permanent hearing impairment because these cells cannot regenerate. By contrast, newborn mammals possess limited regenerative capacity because of the active participation of various signaling pathways, including Wnt and Notch signaling. The Wnt and Notch pathways are highly sophisticated and conserved signaling pathways that control multiple cellular events necessary for the formation of sensory hair cells. Both signaling pathways allow resident supporting cells to regenerate hair cells in the neonatal cochlea. In this regard, Wnt and Notch signaling has gained increased research attention in hair cell regeneration. This review presents the current understanding of the Wnt and Notch signaling pathways in the auditory portion of the inner ear and discusses the possibilities of controlling these pathways with the hair cell fate determiner Atoh1 to regulate hair cell regeneration in the mammalian cochlea.

关键词： inner ear     cochlea     hair cell     regeneration     Wnt     Notch     signaling pathways    

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Stress field near circular-arc interface crack tip based on electric saturation concept

Longchao DAI, Xinwei WANG

《机械工程前沿（英文）》 2009年 第4卷 第3期   页码 320-325 doi: 10.1007/s11465-009-0042-9

摘要： Within the framework of nonlinear electroelasticity, the anti-plane problem of a circular-arc interfacial crack between a circular piezoelectric inhomogeneity and an infinite piezoelectric matrix subjected to a far-field uniform loading is investigated by an electrical strip saturation model, the complex variable method, and the method of analytical continuation. Explicit closed form expressions for the complex potentials in both the matrix and the inclusion, and the stress intensity factor at the crack tip are presented. Comparison with some related solutions based on the linear electroelastic theory shows the validity of the present solutions

关键词： piezoelectric material     arc crack     strip saturation     stress intensity factor    

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Unidirectional and stage-dependent roles of Notch1 in Wnt-responsive Lgr5

Hui Jiang, Shan Zeng, Wenli Ni, Yan Chen, Wenyan Li

《医学前沿（英文）》 2019年 第13卷 第6期   页码 705-712 doi: 10.1007/s11684-019-0703-y

摘要： Wnt and Notch signaling play crucial roles in the determination of the prosensory domain and in the differentiation of hair cells (HCs) and supporting cells during mouse inner ear development; however, the relationship between the two signaling pathways in the mouse cochlea remains largely unknown. Here, we investigated the interactions between Notch and Wnt signaling on the basis of the bidirectional regulation of Notch1 specifically in Wnt-responsive Lgr5 progenitors during different cochlear development stages. We found that the downregulation of Notch1 in Lgr5 cells from embryonic day (E) 14.5 to E18.5 can drive the quiescent Lgr5 cells to re-enter the cell cycle and differentiate into extra HCs, whereas the upregulation of Notch1 expression did not affect the proliferation or differentiation of otic progenitor cells. No effect was observed on the upregulation or downregulation of Notch1 in Lgr5 cells from E10.5 to E14.5. We concluded that the roles of Notch1 in Wnt-responsive Lgr5 cells are unidirectional and stage dependent and Notch1 serves as a negative regulator for Lgr5 progenitor activation during cochlear differentiation. Our findings improved the understanding of the interactions between Notch and Wnt signaling in cochlear development.

关键词： inner ear     cochlear     Wnt     Notch     Lgr5     auditory system    

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论混凝土坝的几个重要问题

朱伯芳

《中国工程科学》 2006年 第8卷 第7期   页码 21-29

摘要：

目前我国在建混凝土坝的高度、数量、规模均居世界第一位，文章就混凝土坝技术的几个重要问题进行讨论：（1）结束“无坝不裂”历史的关键技术；（2）应用氧化镁混凝土筑坝的两种指导思想和两种实践结果；（3）混凝土强度等级应用于混凝土坝欠妥，坝工混凝土仍以采用混凝土标号为宜；（4）我国特高拱坝的抗压安全系数偏低，应适当提高。（5）拱坝有限元等效应力问题。

关键词： 混凝土坝     裂缝     混凝土标号     抗压安全系数     有限元等效应力    

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Mixed mode properties of CNT reinforced composites using Arcan test rig

Jacob MUTHU

《结构与土木工程前沿（英文）》 2015年 第9卷 第4期   页码 397-404 doi: 10.1007/s11709-015-0321-y

摘要： Composite materials reinforced with carbon nanotubes were mechanical tested using Arcan test rig under Mode-I, Mode-II and mixed mode loading conditions to obtain their fracture properties. The butterfly composite specimens were fabricated with 0.02, 0.05 and 0.1 wt % CNTs. The polyester/CNT composite was fabricated using VRTM (Vacuum Resin Transfer Molding) where the CNTs were first functionalised to reach an optimum properties. Arcan test rig was designed and fabricated to work with the Shimadzu testing machine. The results show that the functionalised CNTs have improved the fracture behavior by acting as bridge between the cracked face. In addition, the fracture properties were not improved for the higher weight fraction of 0.1 wt% CNTs.

关键词： CNT     composites     Arcan test rig     stress intensity factor    

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An investigation on prevalent strategies for XFEM-based numerical modeling of crack growth in porous media

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 914-936 doi: 10.1007/s11709-021-0750-8

摘要： Crack growth modeling has always been one of the major challenges in fracture mechanics. Among all numerical methods, the extended finite element method (XFEM) has recently attracted much attention due to its ability to estimate the discontinuous deformation field. However, XFEM modeling does not directly lead to reliable results, and choosing a strategy of implementation is inevitable, especially in porous media. In this study, two prevalent XFEM strategies are evaluated: a) applying reduced Young’s modulus to pores and b) using different partitions to the model and enriching each part individually. We mention the advantages and limitations of each strategy via both analytical and experimental validations. Finally, the crack growth is modeled in a natural porous media (Fontainebleau sandstone). Our investigations proved that although both strategies can identically predict the stress distribution in the sample, the first strategy simulates only the initial crack propagation, while the second strategy could model multiple cracks growths. Both strategies are reliable and highly accurate in calculating the stress intensity factor, but the second strategy can compute a more reliable reaction force. Experimental tests showed that the second strategy is a more accurate strategy in predicting the preferred crack growth path and determining the maximum strength of the sample.

关键词： numerical modeling     extended finite element method     porous media     crack growth     stress intensity factor    

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Crack propagation with different radius local random damage based on peridynamic theory

《结构与土木工程前沿（英文）》 2021年 第15卷 第5期   页码 1238-1248 doi: 10.1007/s11709-021-0695-y

摘要： Drawing from the advantages of Classical Mechanics, the peridynamic theory can clarify the crack propagation mechanism by an integral solution without initially setting the factitious crack and crack path. This study implements the peridynamic theory by subjecting bilateral notch cracked specimens to the conditions of no local damage, small radius local damage, and large radius local damage. Moreover, to study the effects of local stochastic damage with different radii on the crack propagation path and Y-direction displacement, a comparison and contact methodology was adopted, in which the crack propagation paths under uniaxial tension and displacement in the Y-direction were compared and analyzed. This method can be applied to steel structures under similar local random damage conditions.

关键词： peridynamics     stochastic damage     bilateral notch crack    

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标题 作者 时间 类型 操作

Parametric equations for notch stress concentration factors of rib–deck welds under bending loading

期刊论文

The formation mechanism and the influence factor of residual stress in machining

null

期刊论文

以土体应力状态计算边坡安全系数的方法

王国体

期刊论文

Finite element analysis of stress concentrations and failure criteria in composite plates with circular

null

期刊论文

Relationship between expression of hepatocyte grow factor and apoptosis of trophoblasts in hypertensive

OUYANG Shan, ZHANG Qinghua, QIAO Fuyuan

期刊论文

腐蚀环境下飞机结构疲劳寿命的分析方法

穆志韬

期刊论文

Chidamide inhibits the NOTCH1-MYC signaling axis in T-cell acute lymphoblastic leukemia

期刊论文

Measurement of trimethylamine concentration and evaluation of pig meat natural quality by a spectrophotometric

Mohammod Abdul HAMID,Xi WANG,Xiangdong DING,Chuduan WANG,Xingbo ZHAO

期刊论文

Role of Wnt and Notch signaling in regulating hair cell regeneration in the cochlea

null

期刊论文

Stress field near circular-arc interface crack tip based on electric saturation concept

Longchao DAI, Xinwei WANG

期刊论文

Unidirectional and stage-dependent roles of Notch1 in Wnt-responsive Lgr5

Hui Jiang, Shan Zeng, Wenli Ni, Yan Chen, Wenyan Li

期刊论文

论混凝土坝的几个重要问题

朱伯芳

期刊论文

Mixed mode properties of CNT reinforced composites using Arcan test rig

Jacob MUTHU

期刊论文

An investigation on prevalent strategies for XFEM-based numerical modeling of crack growth in porous media

期刊论文

Crack propagation with different radius local random damage based on peridynamic theory

期刊论文