期刊文献+
共找到5,922篇文章
< 1 2 250 >
每页显示 20 50 100
Economic Stress, Precariousness and Risk of High Blood Pressure: A Descriptive Survey of Life Models within Households of the Central Region of Cameroon
1
作者 Jean Ndibi Abanda Ulrich Dama +5 位作者 Viviane Foussouo Ndoungue Anicet Onana Akoa Melkior Fobasso Dzeuta Alphonse Tedonge Asobochia Arsène Emilien Messi Ndzengue Désiré Tchoffo 《Health》 2024年第2期118-130,共13页
Context/Objective: High blood pressure (HBP) currently represents the most widespread chronic non-communicable disease in Cameroon. The increase in its prevalence in the country is the result of multiple factors inclu... Context/Objective: High blood pressure (HBP) currently represents the most widespread chronic non-communicable disease in Cameroon. The increase in its prevalence in the country is the result of multiple factors including economic stress imposed by precariousness, poor living conditions, sources of anxiety, anguish, depression and other behavioral disorders. Economic stress is a globalizing concept that integrates into a purely hermeneutic approach, a particular functioning of the nervous system of an individual who faces employment problems and precarious remuneration conditions. The non-satisfaction by an individual of his basic needs due to insufficient financial means can cause him to become irritable, aggressive, and socially and symbolically isolated, thereby increasing the desire to resort to morbid life models such as excessive consumption of narcotics and other psychoactive substances often associated with high blood pressure. The fight against the emergence of BPH is a complex, multifaceted and multifactorial reality that requires taking into account economic stress. The main objective of this survey is to describe the situation of economic stress within the Cameroonian population, which imposes precariousness and life models at risk of high blood pressure. Specifically, we determined the level of household income and the sources of income. Methods: A cross-sectional survey with a descriptive aim among five hundred households in the Central Region of Cameroon was conducted. A probabilistic technique called simple randomness was used. The number of households to be surveyed was determined indirectly using the Cochrane formula. Data collection in face-to-face mode using a physical questionnaire took place from July 1 to August 31, 2023, after obtaining ethical clearance from the Regional Health Research Ethics Committee, Human from the Center and an administrative authorization for data collection. Regarding their processing, the data was grouped during processing in Excel sheets. Normality and reliability tests of the collected data were carried out. For this, the Chi-square test was used for data with a qualitative value and that of Kolmogorov-Sminorf for data with a quantitative value. Descriptive analysis was possible using R software version 3.2, SPSS version 25.0, XLSTAT 2016, PAST and EXCEL programs from Microsoft Office 2013. Results: The main results highlight economic stress, with 45.60% of households surveyed earning less than US$154 per month;55% of household heads were women in single-parent families;14% of household heads were unemployed, 22% worked in the private sector and 19% were self-employed. This general economic situation leads to precarious living conditions, thereby increasing the risk of high blood pressure among the Cameroonian population. 展开更多
关键词 Economic Stress PRECARIOUSNESS High Blood Pressure life models Households
下载PDF
Assessment of Satisfaction with Life among Elderly Patients Receiving HIV Care and Treatment in Mulago HIV Clinic: A Chronic Illness Quality of Life Model
2
作者 Francis Kalule Alimah Komuhangi +2 位作者 Micheal Buwembo Thomas Katairo Martha Tusabe 《World Journal of AIDS》 2021年第4期152-180,共29页
<strong>Objective:</strong> This study aimed at assessing satisfaction with life among elderly HIV patients attending Mulago HIV Clinic. <strong>Methodology:</strong> A cross-sectional study de... <strong>Objective:</strong> This study aimed at assessing satisfaction with life among elderly HIV patients attending Mulago HIV Clinic. <strong>Methodology:</strong> A cross-sectional study design carried out among elderly people (>50 years old) attending Mulago HIV clinic, as stated by the WHO standard age cut-off of >50 years. A random selection of 353 elderly HIV patients was made. The study collected quantitative data to assess patient satisfaction with life, Illness related to discrimination, Barriers to healthcare and social services, and Physical wellbeing, social support and coping using quantitative data collection techniques. Interview discussions were harnessed to obtain patients’ opinions and perceptions and then results grouped into themes. EPIDATA and STATA 14.2 statistical softwares were used for statistical analysis. <strong>Results:</strong> The study showed that only variables that were significantly associated at multivariate level are, disagreeing that other patients are seen before you when you are first to arrive, which had an odds ratio of 2.87, disagreeing that your employer can never promote you which had an odds ratio of 6.87 compared to agreeing, not being sure whether friend or family member cannot share room/utensil/clothes with you reduced the odds of being satisfied by 95% when compared to agreeing and disagreeing that friend or family member blames you for not getting better with an odds ratio of 5.65 compared to agreeing. <strong>Conclusion:</strong> This study unearthed existing gaps in levels of satisfaction. These shortfalls in the service delivery can be addressed according to the following recommendations below: Create a quick way for elderly patients to see a clinician and give them priority, provide more work-related support awareness programs;Put more efforts towards counselling care takers or family members who help them to adhere or socialize with them. 展开更多
关键词 Quality of life model Elderly HIV Patients Patient Satisfaction ADHERENCE
下载PDF
Remaining Useful Life Model and Assessment of Mechanical Products: A Brief Review and a Note on the State Space Model Method 被引量:9
3
作者 Yawei Hu Shujie Liu +1 位作者 Huitian Lu Hongchao Zhang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2019年第1期11-30,共20页
The remaining useful life(RUL) prediction of mechanical products has been widely studied for online system performance reliability, device remanufacturing, and product safety(safety awareness and safety improvement). ... The remaining useful life(RUL) prediction of mechanical products has been widely studied for online system performance reliability, device remanufacturing, and product safety(safety awareness and safety improvement). These studies incorporated many di erent models, algorithms, and techniques for modeling and assessment. In this paper, methods of RUL assessment are summarized and expounded upon using two major methods: physics model based and data driven based methods. The advantages and disadvantages of each of these methods are deliberated and compared as well. Due to the intricacy of failure mechanism in system, and di culty in physics degradation observation, RUL assessment based on observations of performance variables turns into a science in evaluating the degradation. A modeling method from control systems, the state space model(SSM), as a first order hidden Markov, is presented. In the context of non-linear and non-Gaussian systems, the SSM methodology is capable of performing remaining life assessment by using Bayesian estimation(sequential Monte Carlo). Being e ective for non-linear and non-Gaussian dynamics, the methodology can perform the assessment recursively online for applications in CBM(condition based maintenance), PHM(prognostics and health management), remanufacturing, and system performance reliability. Finally, the discussion raises concerns regarding online sensing data for SSM modeling and assessment of RUL. 展开更多
关键词 REMAINING useful life State space model Online ASSESSMENT BAYESIAN estimation Particle filter REMANUFACTURING
下载PDF
Tool life modeling for evaluating the effects of cutting speed and reinforcements on the machining of particle reinforced metal matrix composites
4
作者 Metin Kk 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2010年第3期353-362,共10页
The wear of cutting tools in the machining of 2024Al alloy composites reinforced with Al2O3 particles using varying sizes and volume fractions of particles up to 23.3vol% was investigated by a turning process using co... The wear of cutting tools in the machining of 2024Al alloy composites reinforced with Al2O3 particles using varying sizes and volume fractions of particles up to 23.3vol% was investigated by a turning process using coated carbide tools K10 and TP30 at different cut- ting speeds. Machining tests were performed with a plan of experiments based on the Taguchi method. The tool life model was developed in terms of cutting speed, size, and volume fraction of particles by multiple linear regressions. The analysis of variance (ANOVA) was also employed to carry out the effects of these parameters on the cutting tool life. The test results show that the tool life decreases with the increase of cutting speed for both cutting tools K10 and TP30, and the tool life of the K10 tool is significantly longer than that of the TP30 tool. For the tool life, cutting speed is found to be the most effective factor followed by particle content and particle size, respectively. The predicted tool life of cutting tools is found to be in very good agreement with the experimentally observed ones. 展开更多
关键词 metal matrix composites analysis of variance mathematical modeling tool life
下载PDF
A Building Information Modeling-Life Cycle Cost Analysis Integrated Model to Enhance Decisions Related to the Selection of Construction Methods at the Conceptual Design Stage of Buildings
5
作者 Nkechi McNeil-Ayuk Ahmad Jrade 《Open Journal of Civil Engineering》 2024年第3期277-304,共28页
Life Cycle Cost Analysis (LCCA) provides a systematic approach to assess the total cost associated with owning, operating, and maintaining assets throughout their entire life. BIM empowers architects and designers to ... Life Cycle Cost Analysis (LCCA) provides a systematic approach to assess the total cost associated with owning, operating, and maintaining assets throughout their entire life. BIM empowers architects and designers to perform real-time evaluations to explore various design options. However, when integrated with LCCA, BIM provides a comprehensive economic perspective that helps stakeholders understand the long-term financial implications of design decisions. This study presents a methodology for developing a model that seamlessly integrates BIM and LCCA during the conceptual design stage of buildings. This integration allows for a comprehensive evaluation and analysis of the design process, ensuring that the development aligns with the principles of low carbon emissions by employing modular construction, 3D concrete printing methods, and different building design alternatives. The model considers the initial construction costs in addition to all the long-term operational, maintenance, and salvage values. It combines various tools and data through different modules, including energy analysis, Life Cycle Assessment (LCA), and Life Cycle Cost Analysis (LCCA) to execute a comprehensive assessment of the financial implications of a specific design option throughout the lifecycle of building projects. The development of the said model and its implementation involves the creation of a new plug-in for the BIM tool (i.e., Autodesk Revit) to enhance its functionalities and capabilities in forecasting the life-cycle costs of buildings in addition to generating associated cash flows, creating scenarios, and sensitivity analyses in an automatic manner. This model empowers designers to evaluate and justify their initial investments while designing and selecting potential construction methods for buildings, and enabling stakeholders to make informed decisions by assessing different design alternatives based on long-term financial considerations during the early stages of design. 展开更多
关键词 life Cycle Cost Analysis (LCCA) Building Information modeling (BIM) Cost Decision Modular Construction and 3D Concrete Printing
下载PDF
Child Life照护模式在先天性心脏病患儿围手术期护理中的应用效果
6
作者 高洋 蔡建平 本乐乐 《深圳中西医结合杂志》 2024年第13期122-125,共4页
目的:探讨Child Life照护模式在先天性心脏病患儿围手术期护理中的应用效果。方法:选取阜外华中心血管病医院2021年4至7月入院的80例先天性心脏病患儿,按照入院时间先后顺序进行分组,其中2021年4至5月入院的患儿分为对照组,2021年6至7... 目的:探讨Child Life照护模式在先天性心脏病患儿围手术期护理中的应用效果。方法:选取阜外华中心血管病医院2021年4至7月入院的80例先天性心脏病患儿,按照入院时间先后顺序进行分组,其中2021年4至5月入院的患儿分为对照组,2021年6至7月入院的患儿分为观察组,各40例。对照组患儿给予围手术期常规护理,观察组患儿在对照组基础上联合Child Life照护模式。比较两组患儿恐惧心理、护理治疗依从性。结果:护理后,两组患儿儿童医疗恐惧量表(CMFS)评分低于护理前,且观察组低于对照组,差异具有统计学意义(P<0.05)。观察组患儿各项护理治疗依从性量表评分高于对照组,差异具有统计学意义(P<0.05)。结论:Child Life照护模式应用于先天性心脏病患儿围手术期,能有效减轻患儿在医疗活动中的恐惧心理,增强其护理治疗依从性,保持患儿心理健康,提高医疗质量。 展开更多
关键词 先天性心脏病 围手术期护理 Child life照护模式
下载PDF
Methods to determine stress profile in ALT based on theoretical life models 被引量:8
7
作者 Chen Yunxia Jing Hailong +1 位作者 Liao Xun Kang Rui 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2015年第3期729-736,共8页
Abstract With the recent products being more reliable, engineers cannot obtain enough failure or degradation information through the design period and even the product lifetime, therefore, accel erated life test (ALT... Abstract With the recent products being more reliable, engineers cannot obtain enough failure or degradation information through the design period and even the product lifetime, therefore, accel erated life test (ALT) ihas become the most popular way to quantify the life characteristics of prod ucts. Test design is the most essential topic, such as testing duration, stress profile, data inference, etc. In this paper, a method and procedure based on theoretical life models is proposed to determine the accelerated stress profile. Firstly, the method for theoretical life calculation is put forward based on the main failure mechanism analysis and the theoretical life models. Secondly, the method is pro vided to determine the accelerated stress profile, including the method to determine the accelerated stress types and the stress range on the basis of the main failure mechanism analysis, the method to determine the acceleration factor and the accelerated stress level based on life quantitative calcula tion models, and the collaborative analysis method of the accelerated test time while taking the mul tiple failure mechanisms into consideration. Lastly, the actuator is taken as an example to describe the procedure of the method and the engineering applicability and the validity are verified. 展开更多
关键词 Acceleration factor Accelerated stress profileALT Failure mechanisms Main failure mechanismanalysis Theoretical life models
原文传递
The Construction of Integrated Nursing Model Prevention of Oxaliplatin Chemotherapy-Induced Peripheral Nerve Injury
8
作者 Qiong Wen Xiaomei Cai 《Journal of Biosciences and Medicines》 2024年第2期340-348,共9页
Objective: To investigate the effect of the integrated nursing model in the prevention of chemotherapy-induced peripheral injury. Methods: A total of 60 tumor patients receiving oxaliplatin for 1 - 6 cycles of chemoth... Objective: To investigate the effect of the integrated nursing model in the prevention of chemotherapy-induced peripheral injury. Methods: A total of 60 tumor patients receiving oxaliplatin for 1 - 6 cycles of chemotherapy from January to September 2023 were selected. 30 patients were selected from January to March and divided into the control group, and 30 patients were selected from July to 9 as the experimental group. The control group received conventional chemotherapy nursing, while the experimental group received integrated nursing. Anxiety, peripheral nerve toxicity stage and quality of life score were compared between the two groups before and after intervention. Results: After intervention, the scores of the self-rating Anxiety Scale (SAS) and the total scores of the oxaliplatin Levi specific sensory neurotoxicity scale in the experimental group were significantly lower than those in the control group, and the differences were statistically significant (P< 0.05);The Quality of Life Scale (FACT-G) score of cancer patients was higher than that of control group, and the difference was statistically significant (P< 0.05). Conclusion: The integrated nursing model can effectively reduce the anxiety of patients, reduce the incidence of peripheral nerve injury and improve the quality of life of patients. 展开更多
关键词 Integrated Nursing Intervention model CHEMOTHERAPY Peripheral Nerve Toxicity ANXIETY Quality of life
下载PDF
Empirical studies of escape behavior find mixed support for the race for life model
9
作者 Kwasi WRENSFORD Jahaziel GUTIERREZ +1 位作者 William E.COOPERJR Daniel T.BLUMSTEIN 《Current Zoology》 SCIE CAS CSCD 2022年第3期305-313,共9页
Escape theory has been exceptionally successful in conceptualizing and accurately predicting effects of numerous factors that affect predation risk and explaining variation in flight initiation distance(FID;predator–... Escape theory has been exceptionally successful in conceptualizing and accurately predicting effects of numerous factors that affect predation risk and explaining variation in flight initiation distance(FID;predator–prey distance when escape begins).Less explored is the relative orientation of an approaching predator,prey,and its eventual refuge.The relationship between an approaching threat and its refuge can be expressed as an angle we call the“interpath angle”or“Φ,”which describes the angle between the paths of predator and prey to the prey’s refuge and thus expresses the degree to which prey must run toward an approaching predator.In general,we might expect that prey would escape at greater distances if they must flee toward a predator to reach its burrow.The“race for life”model makes formal predictions about howΦshould affect FID.We evaluated the model by studying escape decisions in yellow-bellied marmots Marmota flaviventer,a species which flees to burrows.We found support for some of the model’s predictions,yet the relationship betweenΦand FID was less clear.Marmots may not assessΦin a continuous fashion;but we found that binning angle into 445°bins explained a similar amount of variation as models that analyzed angle continuously.Future studies ofΦ,especially those that focus on how different species perceive relative orientation,will likely enhance our understanding of its importance in flight decisions. 展开更多
关键词 antipredator behavior escape behavior escape theory escape trajectory race for life model
原文传递
Effect of Strain Ratio on Fatigue Model of Ultra-fine Grained Pure Titanium
10
作者 QIANG Meng YANG Xirong +1 位作者 LIU Xiaoyan LUO Lei 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2023年第5期1169-1178,共10页
The ultra-fine grained(UFG)pure titanium was prepared by equal channel angular pressing(ECAP)and rotary swaging(RS).The strain controlled low cycle fatigue(LCF)test was carried out at room temperature.The fatigue life... The ultra-fine grained(UFG)pure titanium was prepared by equal channel angular pressing(ECAP)and rotary swaging(RS).The strain controlled low cycle fatigue(LCF)test was carried out at room temperature.The fatigue life prediction model and mean stress relaxation model under asymmetrical stress load were discussed.The results show that the strain ratio has a significant effect on the low cycle fatigue performance of the UFG pure titanium,and the traditional Manson-coffin model can not accurately predict the fatigue life under asymmetric stress load.Therefore,the SWT mean stress correction model and three-parameter power curve model are proposed,and the test results are verified.The final research shows that the threeparameter power surface model has better representation.By studying the mean stress relaxation phenomenon under the condition of R≠-1,it is revealed that the stress ratio and the strain amplitude are the factors that significantly afiect the mean stress relaxation rate,and the mean stress relaxation model with the two variables is calculated to describe the mean stress relaxation phenomenon of the UFG pure titanium under different strain ratios.The fracture morphology of the samples was observed by SEM,and it was concluded that the final fracture zone of the fatigue fracture of the UFG pure titanium was a mixture of ductile fracture and quasi cleavage fracture.The toughness of the material increases with the increase of strain ratio at the same strain amplitude. 展开更多
关键词 ultra-fine grained pure titanium low cycle fatigue life model mean stress relaxation mode strain ratio fracture morphology
下载PDF
Grain size based low cycle fatigue life prediction model for nickel-based superalloy 被引量:13
11
作者 Peng ZHANG Qiang ZHU +2 位作者 Gang CHEN He-yong QIN Chuan-jie WANG 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2018年第10期2102-2106,共5页
Nickel-based superalloys are easy to produce low cycle fatigue(LCF)damage when they are subjected to high temperature and mechanical stresses.Fatigue life prediction of nickel-based superalloys is of great importance ... Nickel-based superalloys are easy to produce low cycle fatigue(LCF)damage when they are subjected to high temperature and mechanical stresses.Fatigue life prediction of nickel-based superalloys is of great importance for their reliable practical application.To investigate the effects of total strain and grain size on LCF behavior,the high temperature LCF tests were carried out for a nickel-based superalloy.The results show that the fatigue lives decreased with the increase of strain amplitude and grain size.A new LCF life prediction model was established considering the effect of grain size on fatigue life.Error analyses indicate that the prediction accuracy of the new LCF life model is higher than those of Manson-Coffin relationship and Ostergren energy method. 展开更多
关键词 nickel-based superalloy low cycle fatigue life prediction model grain size
下载PDF
Reliability estimation and remaining useful lifetime prediction for bearing based on proportional hazard model 被引量:7
12
作者 王鹭 张利 王学芝 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第12期4625-4633,共9页
As the central component of rotating machine,the performance reliability assessment and remaining useful lifetime prediction of bearing are of crucial importance in condition-based maintenance to reduce the maintenanc... As the central component of rotating machine,the performance reliability assessment and remaining useful lifetime prediction of bearing are of crucial importance in condition-based maintenance to reduce the maintenance cost and improve the reliability.A prognostic algorithm to assess the reliability and forecast the remaining useful lifetime(RUL) of bearings was proposed,consisting of three phases.Online vibration and temperature signals of bearings in normal state were measured during the manufacturing process and the most useful time-dependent features of vibration signals were extracted based on correlation analysis(feature selection step).Time series analysis based on neural network,as an identification model,was used to predict the features of bearing vibration signals at any horizons(feature prediction step).Furthermore,according to the features,degradation factor was defined.The proportional hazard model was generated to estimate the survival function and forecast the RUL of the bearing(RUL prediction step).The positive results show that the plausibility and effectiveness of the proposed approach can facilitate bearing reliability estimation and RUL prediction. 展开更多
关键词 PROGNOSTICS reliability estimation remaining useful life proportional hazard model
下载PDF
Life Prediction Model of Machine Tool based on Deep Learning 被引量:2
13
作者 HE Jiawei ZHAO Chendi +2 位作者 GAO Ruiyu LIU Xuehui WANG Xue 《International Journal of Plant Engineering and Management》 2021年第1期1-15,共15页
In view of the shortage of traditional life prediction methods for machine tools,such as low accuracy of life prediction and few samples basis attributes,a life prediction model of machine tools combined with machine ... In view of the shortage of traditional life prediction methods for machine tools,such as low accuracy of life prediction and few samples basis attributes,a life prediction model of machine tools combined with machine tool attributes is proposed.The life prediction model of machine tool adopts KL dispersion distribution theory,uses modal superposition method to carry out machine tool life analysis,calculates the theoretical life of machine tool,and then carries on the simulation,obtains the machine tool life prediction value.Compared with the traditional method of machine tool life prediction,the model is based on the application life fatigue damage model,which superimposes the service times and maintenance cycle of the machine tool,derives the influence factor of machine tool life,and obtains the linear relationship between the influence factor of machine tool life and the life of machine tool.The influence factor of machine tool life is introduced as the life prediction parameter of machine tool.The data transformation relationship of HT300 parts is constructed.The original part data is enhanced.The effective training set is obtained.The life prediction model of machine tool based on deep learning is completed.The quantitative analysis of machine tool life is carried out.The experiment of machine tool life prediction using training data set proves the validity of the model.Regression test was carried out on the training data set to reflect the robustness of the model.The prediction accuracy of the model is further verified by Weibull test. 展开更多
关键词 life prediction model machine tool KL divergence metamorphic relation data enhancement
下载PDF
Using hybrid modeling for life cycle assessment of motor bike and electric bike 被引量:1
14
作者 戴杜 冷如波 +1 位作者 张成 王成焘 《Journal of Central South University》 SCIE EI CAS 2005年第S2期77-80,共4页
Life-cycle assessment (LCA) is environmental evaluation of products, materials, and processes over their life cycle. Truncation uncertainty and corresponding uncertainty are main problems occurred in process life cycl... Life-cycle assessment (LCA) is environmental evaluation of products, materials, and processes over their life cycle. Truncation uncertainty and corresponding uncertainty are main problems occurred in process life cycle assessment (PLCA) modeling and economic input-output life cycle assessment (EIOLCA) modeling. Through combination of these two modelings in different life cycle stage and use of an uncertainty reduction strategy, a hybrid life cycle assessment modeling method was proposed in this study. Case studies were presented on gasoline-powered motorbikes (M-bike) and electricity-powered electric bike (E-bike). Web-based software was developed to analyze process environmental impacts. Results show that the largest part of life cycle energy (LCE) is consumed at use stage. Less energy is consumed in life cycle of E-bike than that of M-bike. GWP (Global Warming Potential), CO (Carbon Monoxide), PM10 (particulate matter) emission of M-bike are higher than that of E-bike, especially at use stage, AP (acidification Potential) emission of E-bike is higher than that of M-bike. Comprehensively, E-bike is energy efficient and less emitting, and better choice for urban private transportation. 展开更多
关键词 life CYCLE assessment hybrid modeling BIKE
下载PDF
Life Prediction Model for a Nickel-base Single Crystal Superalloy DD3
15
作者 岳珠峰 杨治国 吕震宙 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2002年第4期239-243,共5页
The possibility of a life prediction model for nickel base single crystal blades has been studied. The fatigue creep (FC) and thermal fatigue creep(TMFC) as well as creep experiments have been carried out with differe... The possibility of a life prediction model for nickel base single crystal blades has been studied. The fatigue creep (FC) and thermal fatigue creep(TMFC) as well as creep experiments have been carried out with different hold time of DD3. The hold time and the frequency as well as the temperature range are the main factors influencing the life. An emphasis has been put on the micro mechanism of the rupture of creep, FC and TMFC. Two main factors are the voiding and degeneration of the material for the cre... 展开更多
关键词 nickel base single crystal superalloy life prediction model thermal fatigue creep
下载PDF
Bi-variable damage model for fatigue life prediction of metal components 被引量:1
16
作者 Miao Zhang Qing-Chun Meng Xing Zhang Wei-Ping Hu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2011年第3期416-425,共10页
Based on the theory of continuum damage mechanics,a bi-variable damage mechanics model is developed,which,according to thermodynamics,is accessible to derivation of damage driving force,damage evolution equation and d... Based on the theory of continuum damage mechanics,a bi-variable damage mechanics model is developed,which,according to thermodynamics,is accessible to derivation of damage driving force,damage evolution equation and damage evolution criteria. Furthermore,damage evolution equations of time rate are established by the generalized Drucker's postulate. The damage evolution equation of cycle rate is obtained by integrating the time damage evolution equations,and the fatigue life prediction method for smooth specimens under repeated loading with constant strain amplitude is constructed. Likewise,for notched specimens under the repeated loading with constant strain amplitude,the fatigue life prediction method is obtained on the ground of the theory of conservative integral in damage mechanics. Thus,the material parameters in the damage evolution equation can be obtained by reference to the fatigue test results of standard specimens with stress concentration factor equal to 1,2 and 3. 展开更多
关键词 Bi-variable damage model - Damage evolution equation . life prediction - Fatigue . Damage mechanics
下载PDF
Life Distribution Transformation Model of Planetary Gear System 被引量:2
17
作者 Ming Li Li-Yang Xie +1 位作者 Hai-Yang Li Jun-Gang Ren 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2018年第2期208-215,共8页
Planetary gear systems have been widely used in transportation, construction, metallurgy, petroleum, aviation and other industrial fields. Under the same condition of power transmission, they have a more compact struc... Planetary gear systems have been widely used in transportation, construction, metallurgy, petroleum, aviation and other industrial fields. Under the same condition of power transmission, they have a more compact structure than ordinary gear train. However, some critical parts, such as sun gear, planet gear and ring gear often suffer from fatigue and wear under the conditions of high speed and heavy load. For reliability research, in order to predict the fatigue probability life of planetary gear system, detailed kinematic and mechanical analysis for a planetary gear system is firstly completed. Meanwhile, a gear bending fatigue test is carried out at a stress level to obtain the strength information of specific gears. Then, a life distribution transformation model is established according to the order statistics theory. Transformation process is that, the life distribution of test gear is transformed to that of single tooth, and then the life distribution of single tooth can be effectively transformed to that of the planetary gear system. In addition, the effectiveness of the transformation model is finally verified by a processing method with random censoring data. 展开更多
关键词 Planetary gear system Reliability modeling Probabilistic life Random censoring data
下载PDF
Reduced Life Expectancy Model Analyses of Exposure Time Effects of Endocrine Disruptors to Teleost Fishes Based on Effect Concentration of Hepatic Biomarkers
18
作者 Mengtian Sun Hualong Chen Ling Zhao 《Journal of Environmental Protection》 2020年第7期540-550,共11页
In this current paper, the exposure time effects on four endocrine disruptors and teleost fishes were evaluated using the reduced life expectancy (RLE) model based on the effect concentration (EC<sub>50</sub&... In this current paper, the exposure time effects on four endocrine disruptors and teleost fishes were evaluated using the reduced life expectancy (RLE) model based on the effect concentration (EC<sub>50</sub>) of available literature published. The result on the regression analysis over different exposure times has demonstrated that the EC<sub>50</sub> of hepatic biomarkers falls with increasing exposure times in a predictable manner. The slopes of the regression equations reflect the strength of the toxic effects on the various teleost fish. The EC<sub>50</sub> reduction over time can be interpreted based on the bioconcentration process, which can be used to understand transfer routes of the compounds from water to fish body. RLE model also provides useful information in assessing the toxic effects on fish life expectancy as a result of the occurrence of compounds. 展开更多
关键词 Reduced life Expectancy model Endocrine Disruptors Effect Concentration Hepatic Biomarkers Teleost Fishes
下载PDF
基于DP-Modeler的实景三维校园精细化模型构建 被引量:3
19
作者 郭昕怡 刘军 +1 位作者 陈毓洁 胡泽坤 《山西建筑》 2023年第24期165-168,193,共5页
无人机倾斜摄影测量自动化三维建模技术具备高效率、低成本和高精度的特点,已经得到了广泛应用。为了进一步提升实景三维模型的质量,以防灾科技学院校园为例,在实景三维模型自动化构建基础上,利用DP-Modeler完成了三维场景的修饰和建筑... 无人机倾斜摄影测量自动化三维建模技术具备高效率、低成本和高精度的特点,已经得到了广泛应用。为了进一步提升实景三维模型的质量,以防灾科技学院校园为例,在实景三维模型自动化构建基础上,利用DP-Modeler完成了三维场景的修饰和建筑物精细化单体建模。结果表明:DP-Modeler软件直接在倾斜三维模型上交互式单体化建模,具有自动化程度高、简单易用等特点,能够有效提升三维建模的效率,所构建的实景三维模型能够客观真实地反映校园场景。 展开更多
关键词 无人机倾斜摄影 实景三维模型 DP-modeler 单体化
下载PDF
Feature Based Machining Process Planning Modeling and Integration for Life Cycle Engineering
20
作者 LIU Changyi (College of Mechanical and Electrical Engineering,Nanjing University of Aeronautics & Astronautics,Nanjing 210016,China 《武汉理工大学学报》 CAS CSCD 北大核心 2006年第S2期633-636,共4页
Machining process data is the core of computer aided process planning application systems.It is also provides essen- tial content for product life cycle engineering.The character of CAPP that supports product LCE and ... Machining process data is the core of computer aided process planning application systems.It is also provides essen- tial content for product life cycle engineering.The character of CAPP that supports product LCE and virtual manufacturing is an- alyzed.The structure and content of machining process data concerning green manufacturing is also examined.A logic model of Machining Process Data has been built based on an object oriented approach,using UML technology and a physical model of machin- ing process data that utilizes XML technology.To realize the integration of design and process,an approach based on graph-based volume decomposition was apposed.Instead,to solve the problem of generation in the machining process,case-based reasoning and rule-based reasoning have been applied synthetically.Finally,the integration framework and interface that deal with the CAPP integration with CAD,CAM,PDM,and ERP are discussed. 展开更多
关键词 COMPUTER aided process planning FEATURE life CYCLE engineering modeling INTEGRATION
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部