Methods for Reliability Assessment under Irregular Time-Varying-Stress Degradation Testing

Degradation tests are often used to assess the reliability of products with long failure-time or few test units. Much of the previous work on reliability assessment methods has focused on constant-stress degradation test( CSDT) and accelerated degradation test( ADT), mainly under the constant, step or progressive stresses. However,in actual testing environments,some stresses are difficult to control and vary with time irregularly,which are quite different from the three stresses mentioned above. In this paper a new approach was presented for reliability assessment with degradation data under irregular time-varying-stress( ITVS).Firstly,the conventional degradation path modeling method was improved by taking into account the influences of the variable stress on the degradation variable. Then,an example was conducted to show the effectiveness of our improved model.

Using the nematode Caenorhabditis elegans as a model animal for assessing the toxicity induced by microcystin-LR

Among more than 75 variants of microcystin （MC）, microcystin-LR （MC-LR） is one of the most common toxins. In this study, the feasibility of using Caenorhabditis elegans to evaluate MC-LR toxicity was studied. C. elegans was treated with MC-LR at different concentrations ranging from 0.1 to 80 μg/L. The results showed that MC-LR could reduce lifespan, delay development, lengthen generation time, decrease brood size, suppress locomotion behavior, and decreases hsp-16-2-gfp expression. The endpoints of generation time, brood size, and percentage of the population expressing hsp-16-2-gfp were very sensitive to 1.0μg/L of MC-LR, and would be more useful for the evaluation of MC-LR toxicity. Furthermore, the tissue-specific hsp-16-2-gfp expressions were investigated in MC-LR-exposed animals, and the nervous system and intestine were primarily affected by MC-LR. Therefore, the generation time, brood size, and hsp-16-2-gfp expression in C. elegans can be explored to serve as valuable endpoints for evaluating the potential toxicity from MC-LR exposure.

Quantitative Assessment and Zonation of Regional Crustal Stability in China

On the basis of the synthetic analysis of present regional tectonic stress field in China, this paper follows three steps to do crustal stability assessment: (1) zonation of preevaluation area for regional crustal stability assessment and zonation; (2) choice, taking value and weight distribution of quantitative evaluation indices and determination of evaluation standards; (3) assessment and zonation of regional crustal stability using fuzzy mathematics in China.

Peritraumatic Behavior Questionnaire- Observer Rated: Validation of the objective version of a measure for combatrelated peritraumatic stress

AIM: To validate the first third-person-rated measure assessing combat-related peritraumatic stress symptoms and evaluate its psychometric properties and war-zone applicability.METHODS: The valid assessment of peritraumatic symptoms in the theater of military operations represents a significant challenge in combat-related, mental health research, which mainly relies on retrospective, subjective self-report ratings. This longitudinal observational study used data from actively deployed troops to correlate third-person observer ratings of deployment peritraumatic behaviors [Peritraumatic Behavior Questionnaire- Observer Rated(PBQ-OR)] collected on a bimonthly basis with post-deployment(1-wk follow-up) ratings of the previously validated PBQ self-rate version(PBQ-SR), and(3-mo follow-up) clinician assessed and self-report posttraumatic stress disorder(PTSD) symptoms(Clinician Administered PTSD Scale, PTSD Checklist). Cronbach's alpha(α) and correlation coefficients were calculated to assess internal reliability and concurrent validity respectively. RESULTS: Eight hundred and sixty male Marines were included in this study after signing informed consents at pre-deployment(mean age 23.2 ± 2.6 years). Although our findings were limited by an overall sparse return rate of PBQ-OR ratings, the main results indicate satisfactory psychometric properties with good internal consistency for the PBQ-OR(α = 0.88) and high convergent and concurrent validity with 1-wk post-deployment PBQSR ratings and 3-mo posttraumatic stress symptoms. Overall, later PBQ-OR report date was associated with higher correlation between PBQ-OR and postdeployment measures. Kappa analysis between PBQOR and PBQ-SR single items, showed best agreement in questions relating of mortal peril, desire for revenge, and experience of intense physical reactions. Logistic regression demonstrated satisfactory predictive validity of PBQ-OR total score with respect to PTSD caseness(OR = 1.0513; 95%CI: 1.011-1.093; P = 0.02).CONCLUSION: Since no comparable tools have been developed, PBQ-OR could be valuable as real-time screening tool for earlier detection of Service Members at risk.

Fuelwood assessment at the micro-watershed level:a case study in Garhwal Himalaya,India

Biomass,as fuelwood,is one of the major sources of energy in rural areas,especially in the mountainous regions of the world.As the increasing human population exerts more pressure on the forest thereby inducing an adverse effect on the sustainability of the ecosystem,which consequently causes fuelwood crisis at a local level,this crisis is spatio-temporal in nature.Thus,the major objective of this study is to assess the sustainability of fuelwood at different probable scenarios at a micro watershed level.The present study was conducted in the Phakot watershed,the Tehri Garhwal district of central Himalaya in India,during 2006-2008.Based on the vegetation composition in the study area,the net primary productivity(NPP)value of the Oak forest,and mixed oak and sal forests,was used for the quantification of fuelwood availability in evergreen and deciduous forests,respectively.The fuelwood demand was calculated on the basis of seasonal fuelwood consumption values.Nine probable permutations for availability-demand scenarios assuming the existence of high(H),low(L)and average(A)conditions were analyzed for evaluating the stress.The available annual harvestable fuelwood in the watershed is in the minimum and maximum ranges of 2283.28 to 4066.00 tons,respectively,per year whereas it has a demand of 110.76 tons as the minimum to 3659 tons as the maximum annually.This shows that in the current availabilitydemand scenario,the watershed does not have fuelwood crisis in the present situation but needs to maintain the sustainability of the system.Based on our study,it is concluded that,globally,more spatio-temporal study is required to understand the issues at the local level.

Prevention of stress-related ulcer bleeding at the intensive care unit: Risks and benefits of stress ulcer prophylaxis

Stress-related mucosal disease is a typical complication of critically ill patients in the intensive care unit(ICU). It poses a risk of clinically relevant upper gastrointestinal(GI) bleeding. Therefore, stress ulcer prophylaxis(SUP)is recommended in high-risk patients, especially those mechanically ventilated > 48 h and those with a manifest coagulopathy. Proton pump inhibitors(PPI) and, less effectively, histamine 2 receptor antagonists(H2RA) prevent GI bleeding in critically ill patients in the ICU. However, the routine use of pharmacological SUP does not reduce overall mortality in ICU patients. Moreover, recent studies revealed that SUP in the ICU might be associated with potential harm such as an increased risk of infectious complications, especially nosocomial pneumonia and Clostridium difficile-associated diarrhea. Additionally, special populations such as patients with liver cirrhosis may even have an increased mortality rate if treated with PPI. Likewise, PPI can be toxic for both the liver and the bone marrow, and some PPI show clinically relevant interactions with important other drugs like clopidogrel. Therefore, the agent of choice, the specific balance of risks and benefits for individual patients as well as the possible dose of PPI has to be chosen carefully. Alternatives to PPI prophylaxis include H2 RA and/or sucralfate. Instead of routine SUP, further trials should investigate risk-adjusted algorithms, balancing benefits and threats of SUP medication in the ICU.

儿科手术患者术中获得性压力性损伤风险评估量表的构建及应用研究

目的 构建儿科手术患者术中获得性压力性损伤(IAPI)风险评估量表并探讨其应用效果。方法 选取2022年8月至2023年5月湖南省儿童医院106例儿科手术患者为研究对象,通过文献回顾和德尔菲专家函询,生成IAPI风险评估量表,将函询后生成的量表应用到临床,开展信效度检验及预测IAPI发生的效能。结果 两轮函询结果显示,专家积极性较高、权威程度较高、意见比较集中、一致性较高。最终量表包括手术时间、体位、美国麻醉医师协会分级、营养状态、体重指数、术中受压处皮肤情况、术前肢体活动、组织灌注8个条目,量表Cronbach’s α系数为0.705,分半信度为0.725,问卷水平内容效度指数为0.832,条目水平内容效度指数为0.805~1.000。使用Munro量表作为效标,术前、术中、术后评分的相关系数分别为0.377、0.415、0.513。量表预测IAPI发生的曲线下面积为0.810,灵敏度为70.8%、特异度为81.5%、临界值为13.5分。结论 构建的量表具有较高的权威性和科学性,可作为儿科手术患者IAPI风险的评估工具。

基于零点有效缺口应力的薄板焊接接头疲劳评估

文中采用零点有效缺口应力进行了薄板焊接接头的疲劳评估研究.该方法综合考虑整体结构应力以及缺口根部到零点位置的非线性峰值应力的影响,以临界距离法和零点结构应力法为基础,将零点应力位置作为缺口对结构疲劳影响的临界距离对焊接结构进行疲劳强度评估.通过对两种不同类型的焊接接头试样(T形单面焊接头和不同厚度组合搭接接头)的疲劳试验结果进行拟合.结果表明,在对焊根失效的试样进行疲劳评估时,焊根位置不同截面应力线性化之后得到零点有效缺口应力存在较大差异;其中,焊脚截面应力线性化得到的S-N曲线分散带宽度最小;再者,同时考虑焊趾和焊根失效的零点有效缺口应力S-N曲线,与分别考虑焊趾或焊根失效的零点有效缺口应力S-N曲线分散带相差不大,证明该方法可同时用于焊接接头焊趾和焊根疲劳评估.

压力性损伤风险评估表对手术患者压力性损伤发生的护理效果分析

目的探究压力性损伤风险评估表对手术患者压力性损伤发生的护理效果影响。方法随机选取2020年1月-2021年12月潍坊市益都中心医院收治的200例外科手术患者为研究对象,以随机数表法分为观察组和对照组,每组100例。观察组采用Braden压力性损伤评估量表护理干预,对照组采用常规护理干预,对比两组患者的相关指标。结果观察组压力性损伤发生率为6.00%,低于对照组的17.00%,差异有统计学意义(χ^(2)=5.944,P<0.05)。观察组压力性损伤分期结果中,1期4例,2期1例,3期1例,4期0例,和对照组(1期3例,2期4例,3期10例,4期0例)相比,差异无统计学意义(P>0.05)。观察组护理满意度为97.00%,高于对照组87.00%,差异有统计学意义(P<0.05)。结论通过采用压力性损伤风险评估表护理干预,能够对压力性损伤患者的压力性损伤风险进行评估,也能够对患者的恢复情况进行判别。

某在役铆接钢桁梁桥关键构件疲劳性能研究

精准评估现役钢桥的疲劳寿命对于桥梁结构的安全运营至关重要。该文以某在役铆接钢桁梁桥为研究对象,在对桥梁结构进行计算分析明确各构件的受力特点的基础上,针对原桥典型构件以及关键节点开展系列疲劳性能研究。数值计算结果表明,城B荷载作用下原桥典型构件以及关键节点均具有良好抗疲劳性能,疲劳寿命循环次数均大于200万次。

Fatigue Assessment Method for Composite Wind Turbine Blade

Fatigue strength assessment of a horizontal axis wind turbine(HAWT)composite blade is considered.Fatigue load cases are identified,and loads are calculated by the GH Bladed software which is specified at the IEC61400 international specification and GL(Germanisher Lloyd)regulations for the wind energy conversion system.Stress analysis is performed with a 3-D finite element method(FEM).Considering Saint-Venant′s principle,a uniform cross section FEM model is built at each critical zone.Stress transformation matrixes(STM)are set up by applied six unit load components on the FEM model separately.STM can be used to convert the external load into stresses in the linear elastic range.The main material of composite wind turbine blade is fiber reinforced plastics(FRP).In order to evaluate the degree of fatigue damage of FRP,the stresses of fiber direction are extracted and the well-known strength criterion-Puck theory is used.The total fatigue damage of each laminate on the critical point is counted by the rain-flow counting method and Miner′s damage law based on general S-N curves.Several sections of a 45.3mblade of a 2 MW wind turbine are studied using the fatigue evaluation method.The performance of this method is compared with far more costly business software FOCUS.The results show that the fatigue damage of multi-axis FRP can be assessed conveniently by the FEM-STM method.And the proposed method gives a reliable and efficient method to analyze the fatigue damage of slender composite structure with variable cross-sections.

水分胁迫下施用磷石膏改良滨海盐碱土对小麦生长影响与环境风险评估初探

在前期磷石膏改良效果试验的基础上,通过室内盆栽试验,采用滨海盐土种植小麦,磷石膏施用量45 000 kg/hm^(2),进行不同土壤持水量下水分与磷石膏的交互作用对小麦生长影响及环境风险试验,分别设置土壤饱和持水量的90%、80%、70%、60%、50%、40%、30%共7个处理。结果表明,含水量为土壤田间持水量的30%处理比持水量80%处理的小麦株高减少32.06%,总鲜生物量减少44.17%,根生物量增加106.06%,根冠比提高,小麦叶片抗氧化酶活性提高,丙二醛含量增加98.37%;土壤Cd增加3.2%,Pb增加7.2%,Cu增加50.9%,水溶性F增加150%;小麦叶片Cd增加50%,Pb增加33.3%,F增加275%。虽然尚未达到土壤和地下水重金属污染环境质量标准,但是如果长期连续高量施用磷石膏,会导致土壤和地下水相应有害物质积累;小麦叶片中的重金属在灌浆时会逐渐向籽粒转移积累,有一定风险。水分胁迫影响小麦生长发育,导致土壤及小麦叶片中Cd和水溶性F含量提高,会带来小麦籽粒残留Cd和F增加的风险。在气象干旱及盐碱地盐胁迫引起的生理干旱条件下施用磷石膏改良盐碱土可能会引起土壤及地下水环境风险和农产品安全风险,需要加强专项研究和应用监测。

重大事件下城市土地市场公共政策效应评估——基于35个大中城市的实证研究

文章采用季节调整法和HP滤波法,使用35个城市政府、企业和居民三部门的21期季度收入数据,对理论模型中的重大公共卫生事件的影响进行了测度;采用断点回归方法,实证了重大公共卫生事件下公共政策对土地价格的影响,且通过分区和分层进一步进行稳定性检验和异质性检验。研究结果表明,重大公共卫生事件对三部门的运行在短期内仍造成了较大波动,其中房地产企业部门的短期波动最大,对城市土地市场有明显的破坏效应;公共政策对城市土地市场进行了修正,但修正程度随着冲击程度的加大而减小,对不同地区、不同城市、不同用途土地市场的政策效应也有差异。文章为深化关于重大事件下城市土地市场的公共政策效应评估提供了定量判断,为政府部门针对城市土地市场制定更精准有效的公共政策提供了一定的理论支撑。

V形斜缺口薄板结构应力场评估方法研究

文中对含有复杂V形倾斜角的薄板结构应力场进行了理论分析和数值研究.通过建立奇异强度因子as与缺口应力强度因子N-SIF的关系,获得无量纲的N-SIF,在此基础上建立一系列不同几何尺寸、张开角与倾斜角下的有限板宽的斜裂纹切口薄板模型,对切口的应力场进行简化与拟合.通过控制变量法得到奇异强度因子与无量纲N-SIF的关系曲线,拟合得到简易的V形倾斜角的薄板结构应力场和N-SIF评估公式.将拟合出的N-SIF简化计算公式和有限元计算结果与传统文献计算结果进行对比与误差分析.结果表明:拟合出的应力场公式精度较高,可实现复杂倾斜角下V形切口应力场的快速评估.

体外受精-胚胎移植患者生育压力评估工具的研究进展

本文对体外受精-胚胎移植患者生育压力的普适性、特异性评估工具的主要内容、特征及应用现状进行综述,提出未来研究者应进一步进行相关量表的开发和汉化工作,有效识别和管理体外受精-胚胎移植患者的生育压力。

The Naples-Questionnaire of Work Distress (nQ-WD): Bullying at workplace, organizational dysfunctions and bio-psycho-social effects

The aim of this study is to elaborate a tool, the “Naples-Questionnaire of Work Distress” (nQ-WD), in order to evaluate the conditions of discomfort perceived in the working field. It tries to differentiate the dysfunctional phenomena more tied to the anomalies of the interpersonal relationships (bullying at work-place) from the phenomena more clearly related to organizational dysfunctions. The inventory measures the overall effects of these two areas on the subject and the spin-off in term of bio-psycho-social functioning. The questionnaire has been administered to a group of 178 workers who showed a work-related psychopathological disturbance and to a control group of 178 subjects without exposure to bullying at workplace or to organizational distress. The statistical analysis demonstrated degree of significant validity and reliability. The degree of internal coherence of the answers proposed is satisfactory. The ROC curves allow the determination of a threshold value which allows separating the workers subjected to mobbing and/or organizational stress from control-workers with an optimal reliability degree. The values of the area under the ROC curves show that the inventory has a high discriminating capacity.

基于氧化应激生物标志物的抗生素制药废水生态风险评价

近年来我国制药产业发展迅速,由此产生了大量的制药废水。制药废水尤其是抗生素制药废水的排放,对水环境造成了潜在威胁。以石家庄市某制药厂达标排放的抗生素制药废水为研究对象,将斑马鱼暴露于不同浓度的抗生素制药废水中(体积分数为10%、40%、70%),分别于第3、6、9、12、15天测定斑马鱼肌肉组织中活性氧自由基(ROS)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽(GSH)、丙二醛(MDA)和磷酸化组蛋白H2AX(γ-H2AX)6项氧化应激生物标志物的活性或含量,并基于生物标志物测定结果计算基于改进的综合生物标志物响应指数(IBR v2)以评价其生态风险。结果表明:抗生素制药废水的胁迫使斑马鱼肌肉组织产生了氧化应激反应,但不同实验组之间的响应时间存在差异,暴露第6天时,70%实验组的ROS含量、CAT活性、GSH含量、MDA含量和γ-H2AX含量均较对照组发生了显著的变化(p<0.001),响应时间早于10%和40%实验组,表明高浓度抗生素制药废水胁迫能够快速诱导斑马鱼产生氧化应激反应;基于6项肌肉组织氧化应激生物标志物的IBR v2值计算结果显示,达标排放的抗生素制药废水仍具有较高的环境风险,且高浓度的制药废水产生的生态风险更加快速和持久。本研究可为抗生素制药废水生态风险评价和相关排放标准的制定和完善提供参考。

机车车体枕梁关键含缺陷结构疲劳寿命评估

为研究枕梁含缺陷结构服役安全问题,首先,基于有限元仿真对比不同尺寸下的底架枕梁结构刚度、挠度,根据最佳结构试验尺寸开展等效疲劳台架试验,获取焊缝关注点的应力分布状态及潜在裂纹位置,并验证枕梁结构与仿真模型的一致性;然后,基于BS 7910:2019标准中结构完整性评估方法,通过引入当量化裂纹缺陷获得结构临界失效状态,实现关键焊缝区域的寿命预测,同时结合断裂力学数值仿真方法,从仿真角度实现局部模型结构的裂纹扩展模拟,对含裂纹缺陷结构的损伤容限进行分析;最后,对比分析基于标准评估的理论方法与数值仿真方法结果的可靠性和差异性。研究结果表明:枕梁子模型结构台架试验与仿真模型的应力分布具有较好的一致性,枕梁结构薄弱区域集中在垂向减振器角焊缝位置,基于BS 7910:2019标准和数值仿真计算得到的减振器座角焊缝表面缺陷临界深度分别为6.50 mm和7.85 mm,对应疲劳载荷循环数分别为1.029×105和1.121×105次,两者评估结果具有较好的一致性。

常规岛汽机旁路调节阀抗震性能研究

为防止常规岛汽机旁路调节阀在地震期间发生共振,致使调节阀与连接管道受到破坏,使用ANSYS软件中Modal模块,对DN 300 Class900汽机旁路调节阀进行模态分析,得到调节阀各阶自振频率。当调节阀的基频高于33 Hz时,使用等效静力法。对调节阀进行抗震分析,得到阀门整体及各部件的等效应力和变形。根据ASME BPVC-Ⅲ中对核级设备抗震的规定,对调节阀在承受地震载荷时的应力强度进行评定,结果表明:阀体、阀盖、阀杆、支架最大应力分别为133.63、77.52、29.46、71.54 MPa,中法兰螺栓最大拉应力为183.23 MPa,最大剪应力为15.36 MPa,均满足抗震强度要求。

不同引种竹子对低温胁迫的生长生理响应

本研究以遂昌雷竹、黄槽早竹、红壳雷竹、临安雷竹、花秆早竹、雷竹和绿槽毛竹(对照)的2年生母竹移栽苗为材料,连续6年研究了自然低温胁迫下不同竹子9个形态与生长生理指标的响应,并采用主成分分析法和隶属函数法对其抗寒性进行了评价。结果表明:自然低温胁迫下,不同竹子的形态均发生明显变化,出现黄化叶片、卷叶等现象;不同竹子之间的生长指标和叶绿素荧光指标的变化幅度存在显著差异,表明不同竹子受到低温胁迫的伤害有所不同。采用主成分分析法,9个单项指标集约于2个主成分,累计贡献率为88.4%。通过隶属函数值D评价抗寒性的强弱,从强到弱依次表现为遂昌雷竹>黄槽早竹>红壳雷竹>雷竹>临安雷竹>花秆早竹。此研究旨在筛选抗寒性较强的优良竹种,为南竹北移提供参考。