Left bundle branch pacing vs biventricular pacing in heart failure patients with left bundle branch block:A systematic review and meta-analysis

BACKGROUND Left bundle branch pacing(LBBP)is a novel pacing modality of cardiac resynchronization therapy(CRT)that achieves more physiologic native ventricular activation than biventricular pacing(BiVP).AIM To explore the validity of electromechanical resynchronization,clinical and echocardiographic response of LBBP-CRT.METHODS Systematic review and Meta-analysis were conducted in accordance with the standard guidelines as mentioned in detail in the methodology section.RESULTS In our analysis,the success rate of LBBP-CRT was determined to be 91.1%.LBBP CRT significantly shortened QRS duration,with significant improvement in echocardiographic parameters,including left ventricular ejection fraction,left ventricular end-diastolic diameter and left ventricular end-systolic diameter in comparison with BiVP-CRT.CONCLUSION A significant reduction in New York Heart Association class and B-type natriuretic peptide levels was also observed in the LBBP-CRT group vs BiVP-CRT group.Lastly,the LBBP-CRT cohort had a reduced pacing threshold at follow-up as compared to BiVP-CRT.

Seismic-induced surficial failure of cohesive slopes using three-dimensional limit analysis:A case study of the Wangjiayan landslide in Beichuan, China

A seismic-induced landslide is a common geological catastrophe that occurs in nature.The Wangjiayan landslide,which was triggered by the Wenchuan earthquake,is a typical case in point.The Wanjiayan landslide caused many casualties and resulted in enormous property loss.This study constructs a simple surficial failure model based on the upper bound approach of three-dimensional(3D)limit analysis to evaluate the slope stability of the Wangjiayan case,while a traditional two-dimensional(2D)analysis is also conducted as a reference for comparison with the results of the 3D analysis.A quasi-static calculation is used to study the effect of the earthquake in terms of horizontal ground acceleration,while a parametric study is conducted to evaluate the critical cohesion of slopes.Rather than employing a 3D analysis,using the 2D analysis yields an underestimation regarding the safety factor.In the Wangjiayan landslide,the difference in the factors of safety between the 3D and 2D analyses can reach 20%.The sliding surface morphology as determined by the 3D method is similar to actual morphology,and the parameters of both are also compared to analyze the reliability of the proposed 3D method.

Three-dimensional limit variation analysis on the ultimate pullout capacity of the anchor cables based on the Hoek-Brown failure criterion

Only simplified two-dimensional model and a single failure mode are adopted to calculate the ultimate pullout capacity(UPC)of anchor cables in most previous research.This study focuses on a more comprehensive combination failure mode that consists of bond failure of an anchorage body and failure of an anchored rock mass.The three-dimensional ultimate pullout capacity of the anchor cables is calculated based on the Hoek-Brown failure criterion and variation analysis method.The numerical solution for the curvilinear function in fracture plane is obtained based on the finite difference theory,which more accurately reflects the failure state of the anchor cable,as opposed to that being assumed in advance.The results reveal that relying solely on a single failure mode for UPC calculations has limitations,as changes in parameter values not only directly impact the UPC value but also can alter the failure model and thus the calculation method.

Meta analysis of the efficacy of western medicine combined with Qiliqiangxin capsule versus western medicine alone in the treatment of chronic heart failure

Objective: To compare the clinical efficacy of conventional Western medicine combined with Qiliqiangxin capsule and western medicine alone in the treatment of chronic heart failure, and to prove that Qiliqiangxin capsule combined treatment has more advantages, providing reference for clinical decision-making in the treatment of chronic heart failure. Methods: Randomized controlled trials (RCTs) of conventional Western medicine treatment and Western medicine combined with Qiliqiangxin capsule in the treatment of chronic heart failure were searched in databases such as PubMed, Embase, Webofscience, CNKI, WanFang, VIP, and CBM. The bias risk assessment was conducted using the RCT tool recommended by Cochrane, and then the meta-analysis was performed using RevMan5.4 and Stata17 software. Compare the efficacy evaluation of cardiac function, left ventricular ejection fraction (LVEF), left ventricular end diastolic diameter (LVEDD), cardiac stroke output (SV), 6-minute walking test (6MWT), and N-terminal proBNP in the conventional western medicine combined with Qiliqiangxin capsule group (hereinafter referred to as the treatment group) and the conventional western medicine group (hereinafter referred to as the control group). Results: A total of 20 RCTs meeting the criteria were included, including 2953 patients, including 1508 in the treatment group and 1445 in the control group. The results of meta-analysis showed that the treatment group had significantly better cardiac function evaluation, LVEF, LVEDD, SV, 6MWT, and NT-proBNP improvement than the control group. Its central functional efficacy evaluation (OR=2.09,95% CI: 1.71-2.55, P<0.001), LVEF (WMD=7.05,95% CI: 5.30-8.79, P<0.00001), LVEDD (WMD=6.73, 95% CI: 3.18-10.29, P=0.0002), SV (WMD=6.73, 95% CI: 3.18-10.29, P=0.0002), 6MWT (SMD=0.70,95% CI: 0.54-0.87, P<0.00001), NT-proBNP (SMD=-1.95,95% CI: -2.5 2 to 1.38 (P<0.0001), with statistically significant differences. Conclusion: Conventional western medicine combined with Qiliqiangxin capsule can significantly improve the clinical efficacy of heart failure, improve LVEF, LVEDD, SV, and NT-proBNP index, and improve exercise tolerance. It is worth using for reference in the treatment.

Bioinformatics Analysis of the Relationship between Dilated Cardiomyopathy and Chronic Heart Failure

Objective: To screen and analyze the differentially expressed genes between dilated cardiomyopathy (DCM) and chronic heart failure (CHF) based on bioinformatics methods. Methods: The Gene Expression Omnibus (GEO) database was used for data retrieval, and the chip data GSE3585 was downloaded, which was the original data of DCM and normal control group. At the same time, the chip data GSE76701 was downloaded, which was the original data of CHF and control group. Differentially expressed mRNAs (DEmRNAs) were screened by R language limma package, the data were standardized, and the common differentially expressed genes were screened. GO function and KEGG pathway enrichment analysis were performed on the common differentially expressed genes. String11.0 online tool was used for data analysis to obtain differentially expressed genes, and the results were imported into Cytoscape 3.9.1 software. The results were imported into Cytoscape 3.9.1 software, and the common expression gene module was obtained by MOCDE algorithm. Nine Hub genes were obtained by 10 algorithms such as MCC. Results: A total of 248 differentially expressed genes were screened. GO analysis showed that differentially expressed genes were mainly concentrated in 9 different physiological and pathological processes. KEGG analysis showed that the main signaling pathways involved in differentially expressed genes were 2, and 9 key differentially expressed genes were predicted: NPPB, NPPA, MYH6, FRZB, ASPN, SFRP4, RPS4Y1, DDX3Y. Conclusion: This study preliminarily explored the molecular mechanism of DCM and CHF, and obtained the common differentially expressed genes of the two diseases. Further experimental studies are needed to verify the correlation between gene expression and clinicopathological features. Provide new ideas for clinical drug treatment research.

Stability analysis of intermittently jointed rock slopes based on the stepped failure mode

In practical engineering,due to the noncontinuity characteristics of joints in rock slopes,in addition to plane failure,stepped sliding failure may occur for intermittently jointed rock slopes.Especially for intermittently bedding jointed rock slopes,the correlation and difference in strength parameters between joints and rock bridges,along with the various failure modes and intermittency of rock bridges,contribute to the complexity of stepped failure modes and the unpredictability of failure regions.Based on the upper-bound limit analysis method and multi-sliders step-path failure mode,considering the shear and tensile failure of rock bridges and the weakened relationship between the strength parameters of rock bridges and jointed surfaces,by introducing the modified M-C failure criterion and the formula for calculating the energy consumption of tensile failure of rock bridges,two failure mechanisms are constructed to obtain the safety factor(F_(s))of intermittently jointed rock slopes.The sequential quadratic programming method is used to obtain the optimal upper-bound solution for F_(s).The influence of multiple key parameters(slope height H,horizontal distance L,Slope angleβ,shear strength parameters of the rock bridgeφr and cr,Dimensionless parameter u,weakening coefficients of the internal friction angle and cohesion between the rock bridges and joint surfaces Kφand Kc)on the stability analysis of intermittently jointed rock slopes under the shear failure mode of rock bridges as well as under the tensile failure mode is also explored.The reliability of the failure mechanisms is verified by comparative analysis with theoretical results,numerical results,and landslide cases,and the variation rules of F_(s)with each key parameter are obtained.The results show that F_(s) varies linearly withφr and cr of the rock bridge and with K_(φ)and K_(c),whereas F_(s)changes nonlinearly with H and L.In particular,with the increase in Kφand Kc,Fs increases by approximately 52.78%and 171.02%on average,respectively.For rock bridge tensile failure,F_(s) shows a nonlinearly positive correlation withφr,cr,Kφand Kc.In particular,with the increase in Kφand Kc,Fs increases by approximately 13%and 61.69%on average,respectively.Fs decreases rapidly with increasing slope gradientβand decreasing dimensionless parameterμ.When Kφand Kc are both less than 1.0,the stepped sliding surface occurs more easily than the plane failure surface,especially in the case of tensile failure of the rock bridge.In addition,rock slopes with higher strength parameters,taller heights,and greater weakening coefficients are prone to rock bridge tension failure with lower Fs,and more attention should be given to the occurrence of such accidents in actual engineering.

Metabolomic-based analysis reveals bile acid-mediated ovarian failure induced by low temperature in zebrafish

As ectotherms, fish are highly sensitive to temperature fluctuations, which can profoundly impact their reproductive cycles. In this study, we investigated the fertility and histological characteristics of zebrafish(Danio rerio) ovaries exposed to a temperature gradient ranging from the thermopreferendum temperature of the species,27℃, to lower temperatures of 22℃, 20℃, and 13℃ over a period of two weeks. Comparative metabolomic(six biological replicates for each temperature) and transcriptomic(four biological replicates for each temperature) analyses were conducted under the four temperature conditions. Results indicated that lower temperatures inhibited oocyte development and differential metabolites were involved in steroid hormone production,antioxidant function, and lipid and protein catabolism.Disrupted reproductive hormones, increased proteolysis,and lipid degradation significantly impeded oocyte development and egg maturation. Notably, a significant increase in bile acid content was noted in the ovaries of the cold-treated fish, indicating that bile acids play a critical role in ovarian failure. Overall, these findings provide valuable insights into the mechanisms governing the reproductive response of fish to cold stress.

Failure Analysis of Dissimilar Metal Welds between Ferritic Heat Resistant Steels and Austenitic Stainless Steels in Power Plant

This study analysed the failure of dissimilar metal welds(DMWs)between ferritic heat resistant steels and austenitic stainless steels and investigated its influencing factors by means of numerical simulation,microstructure characterization and mechanical property test.Under the long-term high-temperature service condition in practical power plant,the DMW failure mode was along the interface between nickel-based weld metal(WM)and ferritic heat resistant steel,and the failure mechanism was stress/strain concentration,microstructure degradation and oxidation coupling acting on the interface.The numerical simulation results show that interface stress/strain concentration was due to the differences in coefficient of thermal expansion and creep strength,and the degree of stress/strain concentration was related to service time.The ferrite band formed at the WM/ferritic steel interface was prone to cracking,attracting the fracture along the interface.The interface crack allowed oxidation to develop along the WM/ferritic steel interface.During long-term service,the interface stress/strain concentration,microstructure and oxidation all evolved,which synergistically promoted interface failure of DMW.However,only under the long-term service of low stress conditions could trigger the interface failure of DMW.Meanwhile,long-term service would reduce the mechanical strength and plasticity of DMW.

Efficacy and safety of Yangxinshi tablet for chronic heart failure:A systematic review and meta-analysis

BACKGROUND The specific benefits of Yangxinshi tablet(YXST)in the treating chronic heart failure(CHF)remain uncertain.AIM To systematically evaluate the efficacy and safety of YXST in the treatment of CHF.METHODS Randomized controlled trials(RCTs)investigating YXST for CHF treatment were retrieved from eight public databases up to November 2023.Meta-analyses of the included clinical studies were conducted using Review Manager 5.3.RESULTS Twenty RCTs and 1845 patients were included.The meta-analysis results showed that the YXST combination group,compared to the conventional drug group,significantly increased the clinical efficacy rate by 23%[relative risk(RR)=1.23,95%CI:1.17-1.29],(P<0.00001),left ventricular ejection fraction by 6.69%[mean difference(MD)=6.69,95%CI:4.42-8.95,P<0.00001]and 6-min walk test by 49.82 m(MD=49.82,95%C:38.84-60.80,P<0.00001),and reduced N-terminal pro-Btype natriuretic peptide by 1.03 ng/L[standardized MD(SMD)=-1.03,95%CI:-1.32 to-0.74,P<0.00001],brain natriuretic peptide by 80.95 ng/L(MD=-80.95,95%CI:-143.31 to-18.59,P=0.01),left ventricular end-diastolic diameter by 3.92 mm(MD=-3.92,95%CI:-5.06 to-2.78,P<0.00001),and left ventricular endsystolic diameter by 4.34 mm(MD=-4.34,95%CI:-6.22 to-2.47,P<0.00001).Regarding safety,neither group reported any serious adverse events during treatment(RR=0.54,95%CI:0.15-1.90,P=0.33).In addition,Egger's test results indicated no significant publication bias(P=0.557).CONCLUSION YXST effectively improves clinical symptoms and cardiac function in patients with CHF while maintaining a favorable safety profile,suggesting its potential as a therapeutic strategy for CHF.

Sub-Homogeneous Peridynamic Model for Fracture and Failure Analysis of Roadway Surrounding Rock

The surrounding rock of roadways exhibits intricate characteristics of discontinuity and heterogeneity.To address these complexities,this study employs non-local Peridynamics(PD)theory and reconstructs the kernel function to represent accurately the spatial decline of long-range force.Additionally,modifications to the traditional bondbased PD model are made.By considering the micro-structure of coal-rock materials within a uniform discrete model,heterogeneity characterized by bond random pre-breaking is introduced.This approach facilitates the proposal of a novel model capable of handling the random distribution characteristics of material heterogeneity,rendering the PD model suitable for analyzing the deformation and failure of heterogeneous layered coal-rock mass structures.The established numerical model and simulation method,termed the sub-homogeneous PD model,not only incorporates the support effect but also captures accurately the random heterogeneous micro-structure of roadway surrounding rock.The simulation results obtained using this model show good agreement with field measurements from the Fucun coal mine,effectively validating the model’s capability in accurately reproducing the deformation and failure mode of surrounding rock under bolt-supported(anchor cable).The proposed subhomogeneous PD model presents a valuable and effective simulation tool for studying the deformation and failure of roadway surrounding rock in coal mines,offering new insights and potential advancements.

Structural failure analysis with CMS-based ground motion selection using innovative cost function and weight factors

The selection and scaling of ground motion records is considered a primary and essential task in performing structural analysis and design.Conventional methods involve using ground motion models and a conditional spectrum to select ground motion records based on the target spectrum.This research demonstrates the influence of adopting different weighted factors for various period ranges during matching selected ground motions with the target hazard spectrum.The event data from the Next Generation Attenuation West 2(NGA-West 2)database is used as the basis for ground motion selection,and hazard de-aggregation is conducted to estimate the event parameters of interest,which are then used to construct the target intensity measure(IM).The target IMs are then used to select ground motion records with different weighted vector-valued objective functions.The weights are altered to account for the relative importance of IM in accordance with the structural analysis application of steel moment resisting frame(SMRF)buildings.Instead of an ordinary objective function for the matching spectrum,a novel model is introduced and compared with the conventional cost function.The results indicate that when applying the new cost function for ground motion selection,it places higher demands on structures compared to the conventional cost function.Moreover,submitting more weights to the first-mode period of structures increases engineering demand parameters.Findings demonstrate that weight factors allocated to different period ranges can successfully account for period elongation and higher mode effects.

Analysis of the Effect of Non-Invasive Positive Pressure Ventilation in Emergency Treatment of Severe Bronchial Asthma with Respiratory Failure

Objective:This study aims to evaluate the clinical efficacy of non-invasive positive pressure ventilation(NIPPV)in patients with severe bronchial asthma combined with respiratory failure.Methods:90 patients with severe bronchial asthma combined with respiratory failure between September 2022 and December 2023 were selected for the study and randomly divided into the experimental group(NIPPV-assisted treatment)and the control group.The differences between the two groups were compared in terms of total effective rate of treatment,days of clinical symptom disappearance,days of hospitalization,lung function indexes,incidence of adverse reactions,and quality of life.Results:Patients in the experimental group had a significantly higher total effective rate of treatment(97.78%)than the control group(75.56%).In terms of pulmonary function indexes,patients in the experimental group showed significant improvement after treatment,especially the increase in forced expiratory volume and forced vital capacity,while these improvements were not as obvious in the control group.In addition,the incidence of adverse reactions was significantly lower in the experimental group than in the control group,suggesting that the application of NIPPV is relatively safe.Quality of life assessment also showed that patients in the experimental group had significantly better quality of life than the control group after treatment.Conclusion:This study demonstrated the effectiveness of NIPPV as an adjunctive treatment for severe bronchial asthma combined with respiratory failure.NIPPV can improve lung function,reduce the incidence of adverse effects,increase the overall effectiveness of the treatment,and contribute to the improvement of patients'quality of life.Therefore,NIPPV should be regarded as an effective and safe treatment in clinical management,especially in patients with severe bronchial asthma combined with respiratory failure,where its application has potential clinical significance.

Application and Satisfaction Analysis of Humanized Quality Nursing Intervention in the Care of Patients with Critical Respiratory Failure

Objective:To implement humanized quality care in critical respiratory failure nursing,observe the effect,and analyze the satisfaction.Methods:80 patients with severe respiratory failure were divided into 40 cases per group(admitted from February 2022 to December 2023)by double-blind method,the control group performed routine care,and the observation group was given humanized quality care.Results:After the nursing care,two respiratory function indexes of the observation group were lower than those of the control group,and two pulmonary function indexes were higher than those of the control group(P<0.05);regarding the complication situation,the incidence rate of the observation group was lower(P<0.05);regarding the nursing care satisfaction situation,the observation group had a higher level of total satisfaction(P<0.05).Conclusion:The application of a humanized quality nursing intervention model in the care of critical respiratory failure can actively improve patients’respiratory status and lung function,reduce complications,and satisfy patients.

Analysis of the Effectiveness of Targeted Nursing in Children with Severe Viral Encephalitis Complicated with Respiratory Failure

Objective:To explore and analyze the effectiveness of targeted nursing in children with severe viral encephalitis complicated with respiratory failure.Methods:From April 2021 to April 2023,74 children with severe viral encephalitis complicated with respiratory failure admitted to the Department of Pediatrics of our hospital were selected as the research objects and divided into the target group(n=37)and the reference group(n=37).Targeted nursing was given to the target group,while general nursing was given to the reference group.Physical rehabilitation,motor scores,and lung function were compared between the groups.Results:The recovery time of limb abnormalities,convulsions,abnormal consciousness,and cranial nerve disorders in the target group was significantly better than that in the reference group(P<0.05).The motor function,joint activity and pain,sensory function,and total score of the target group were significantly lower than those of the reference group(P<0.05).After the intervention,lung function indicators including VC(vital capacity),FVC(forced vital capacity),and MVV(maximum voluntary ventilation)of the target group were better than those of the reference group(P<0.05).Conclusion:Targeted nursing can shorten the recovery period of severe viral encephalitis complicated with respiratory failure in children,speed up the recovery of motor function,and improve lung function.This nursing model has a significant application effect in children with severe viral encephalitis complicated with respiratory failure.

Comprehensive effects of traditional Chinese medicine treatment on heart failure and changes in B-type natriuretic peptide levels: A meta-analysis

BACKGROUND Heart failure(HF),a common cardiovascular condition,is characterized by significant morbidity and mortality.While traditional Chinese medicine(TCM)is often used as a complementary approach in HF management,systematic evalua-tions of its impact on clinical outcomes,TCM syndrome scores,and B-type natriuretic peptide(BNP)levels are lacking.This study fills this gap through a comprehensive analysis of randomized controlled trials(RCTs)focusing on TCM for HF treatment.It encompasses an assessment of methodological quality,a meta-analysis,and an evaluation of evidence quality based on established standards.The results offer crucial insights into the potential advantages and constraints of TCM in HF management.RCTs on TCM for HF treatment published since the establishment of the database were searched in four Chinese and English databases,including China National Knowledge Infrastructure,Wanfang,VIP Information Chinese Science and Technology Journal,and PubMed.Methodological quality was assessed for the included studies with the Cochrane risk-of-bias assessment tool,and the meta-analysis and publication bias assessment was performed with the RevMan5.3 software.Finally,the quality of evidence was rated according to the GRADE criteria.RESULTS A total of 1098 RCTs were initially retrieved.After screening,16 RCTs were finally included in our study,which were published between 2020 and 2023.These RCTs involved 1660 HF patients,including 832 in the TCM group[TCM combined with conventional Western medicine(CMW)treatment]and 828 in the CWM group(CWM treatment).The course of treatments varied from 1 wk to 3 months.TCM syndrome differentiation was analyzed in 11 of the included RCTs.In all included RCTs,outcome indicators included comprehensive clinical outcomes,TCM syndrome scores,and BNP levels.The meta-analysis results showed significant differences between the TCM and CWM groups in terms of comprehensive clinical outcomes[risk ratio=-0.54;95%confidence interval(CI)=-0.61,-0.47;P<0.00001],TCM syndrome scores[weighted mean difference(WMD)=-142.07;95%CI=-147.56,-136.57;P<0.00001],and BNP levels(WMD=-142.07;95%CI=-147.56,-136.57;P<0.00001).According to the GRADE criteria,RCTs where"TCM improves clinical comprehensive outcomes"were rated as low-quality evidence,and RCTs where"TCM reduces TCM syndrome scores"or"TCM decreases BNP levels"were rated as medium-quality evidence.CONCLUSION TCM combined with CWM treatment effectively improves comprehensive clinical outcomes and diminishes TCM syndrome scores and BNP levels in HF patients.Given the low and medium quality of the included RCTs,the application of these results should be cautious.

Analysis of the Effect of Extended Rehabilitation Care at Home on the Psychological Condition and Adherence to Medical Compliance Behavior of Patients with Coronary Heart Disease Combined with Heart Failure

Objective:To analyze the effects of providing extended rehabilitation nursing services at home to patients with coronary heart disease(CHD)combined with heart failure(CHF)on psychological improvement and adherence to medical compliance behavior.Methods:79 patients with CHD with CHF admitted to Sijia Town Central Health Hospital,Haimen District,Nantong City,Jiangsu Province,between June 2021 and June 2023 were selected and grouped according to the randomized numerical table method.The control group(39 cases)was provided with conventional nursing care and extended rehabilitation nursing care at home was provided to the observation group(40 cases).The psychological status,adherence to medical behaviors,cardiac function,and complications between both groups were compared.Results:The scores of anxieties and depression self-assessment scales(SAS,SDS)of patients in the observation group were lower than those of the control group(t=2.954,3.212;P<0.05);the compliance of patients in the observation group was higher than that of the control group(P<0.05).The levels of left ventricular ejection fraction,end-systolic and end-diastolic internal diameters(LVEF,LVESD,LVEDD)of patients in the observation group at 58.02±5.34%,44.49±5.16 mm,and 49.16±5.76 mm respectively were better than those of the control group after nursing care(t=3.205,3.288,2.633;P<0.05);the complication rate of the observation group was lower than that of the control group(P<0.05).Conclusion:Extended rehabilitation nursing at home exhibited a psychological regulation effect on CHD with CHF patients,improved their medical compliance,improved cardiac function,reduced the incidence of complications,and had significant application value.

Finite element failure analysis of continuous prestressed concrete box girders

In order to analyze the load carrying capacity of prestressed concrete box girders, failure behaviors of in-situ deteriorated continuous prestressed concrete box girders under loading are experimentally observed and a finite failure analysis method for predicting behaviors of box girders is developed. A degenerated solid shell element is used to simulate box girders and material nonlinearity is considered. Since pre-stressed concrete box girders usually have a large number of curve prestressed tendons, a type of combined element is presented to simulate the prestressed tendons of box girders, and then the number of elements can be significantly reduced. The analytical results are compared with full-scale failure test results. The comparison shows that the presented method can be effectively applied to the failure analysis of in-situ continuous prestressed concrete box girders, and it also shows that the studied old bridge still has enough load carrying capacity.

Simulation analysis on three-dimensional slope failure under different conditions

The failure mechanism of two-dimensional（2D） and three-dimensional（3D） slopes were investigated by using the strength reduction method.An extensive study of 3D effect was conducted with respect to boundary conditions,shear strength and concentrated surcharge load.The results obtained by 2D and 3D analyses were compared and the applicable scope of 2D and 3D method was analyzed.The results of the numerical simulation show that 3D effect is sensitive to the width of slip surface.As for slopes with specific geometry,3D effect is influenced by dimensionless parameter c/（γHtanφ）.For those infinite slopes with local loading,external load has the major impact on failure mode.For those slopes with local loading and geometric constraints,the failure mode is influenced by both factors.With the increase of loading length,boundary condition exerts a more significant impact on the failure mode,and then 2D and 3D stability charts are developed,which provides a rapid and reliable way to calculate 2D and 3D factor of safety without iteration.Finally,a simple and practical calculation procedure based on the study of 3D effect and stability charts is proposed to recognize the right time to apply 2D or 3D method.

System reliability assessment based on Wiener process and competing failure analysis

Considering the dependence and competitive relation-ship between traumatic failure and degradation,the reliability assessment of products based on competing failure analysis is studied.The hazard rate of traumatic failure is regarded as a Weibull distribution of the degradation performance,and the Wiener process is used to describe the degradation process.The parameters are estimated with the maximum likelihood estimation（MLE）method.A reliability model based on competing failure analysis is proposed.A case study of the GaAs lasers is given to validate the effectiveness of the model and its solving method.The results indicate that if only the degradation failure is considered,the estimated result will be comparably optimistic.Meanwhile,the correlation between the degradation and traumatic failure has a great influence on the accuracy of reliability assessment.

PROGRESSIVE FAILURE ANALYSIS OF LAMINATED COMPOSITES WITH TRANSVERSE SHEAR EFFECTS

This paper deals with the progressive failure analysis of composite laminates. Triangular elements which include the transverse shear effects are us.d for the stress analysis. A new method for the calculation of the shear correction factors is presented. Several failure criteria are used to check the first ply failure and distinguish the laminate failure modes into fiber breakage or buckling, matrix cracking and delamination. After the failure is detected, the stiffness of the failed ply is modified according to the failure modes. The ultimate strength of the laminate is obtained by an iterative way. Several examples are given in the paper for stress analysis and progressive failure analysis of composite laminates.