Stress-deformable state of isotropic double curved shell with internal cracks and a circular hole

This work is devoted to the stress–strain state of isotropic double curved shell with defect system. The construction is weakened by two non-through thickness (internal) cracks of different length and by a circular hole located between cracks. In this study we use the line-spring model. Within the framework of this model cracks are modeled as mathematical cuts of shell’s middle surface. This leads to a two-dimensional problem. The problem is reduced to a system of eight boundary integral equations. To ensure the uniqueness of solution an additional equation is added. In the numerical solution of the problem special quadrature formulas for singular integrals of Cauchy type and the finite difference method are applied. The influence of defects on each other for double curved shell has been investigated. The given theoretical results can be used for the calculation of structural elements with holes, cracks on the strength and fracture toughness in various branches of engineering.     

Risk factors associated with online game addiction: A hierarchical model

Online gaming addiction has been increasingly recognized as a mental disorder. However, the predictive factors that lead to online gaming addiction are not well established. The aim of this study was to identify factors that may influence the development of online gaming addiction. A total of 263 patients with problematic online gaming addiction (255 males (97%) and 8 females (3%), age: mean = 20.4 ± 5.8 years) and153 healthy comparison subjects (118 males (77%) and 35 females (23%), age: 21.2 ± 5.5 years, range) were recruited for participation in the current study. Hierarchical logistic regression analyses among each set of variables were conducted. Individual factors (sex and age), cognitive factors (IQ and perseverative errors), psychopathological conditions (ADHD, depression, anxiety, and impulsivity), and social interaction factors (family environment, social anxiety, and self-esteem) were evaluated in a stepwise fashion. All four factors were associated with online gaming addiction, with psychopathological conditions being the strongest risk factors for the addiction. Individual factors, psychological factors, and social interactions were associated with the development of pure online gaming addiction. As before, psychological factors (attention, mood, anxiety and impulsivity) were the strongest risk factors for online gaming addiction in patients with pure online gaming addiction. Psychopathologies, including ADHD and depression, were the strongest factors associated with the development of online gaming addiction in individuals.     

Ranking of aircraft maintenance organization based on human factor performance

Aircraft maintenance organisation is a complex socio-technical setup, where human factors influence the quality of aircraft maintenance service. Maintenance service quality is assessed based on the commitment of management and its ability to provide suitable facility, tools, spares and manpower supported with comfortable environment and maintenance procedures. Assessment of the service quality of the aircraft maintenance organisation is a complex process. Airlines, regulators, insurance companies and other agencies need decision support system, to assess the performance of a maintenance organisation. This paper provides criteria and scientific approach for assessing the maintenance organisation; it presents a methodology of applying Analytical Hierarchy Process to prioritise the key functions and to rank the maintenance organisations under study. The study has established that maintenance service quality in airline is directly correlated to its fleet size.     

人纤维蛋白原对急诊外伤致创伤性凝血病疗效及相关因素分析

目的:探讨人纤维蛋白原(fibrinogen，FIB)对急诊创伤性凝血病患者的临床疗效及相关因素。方法:将2015年6月至2018年6月本院收治的100例严重创伤患者纳入本研究，根据是否创伤性凝血病分为凝血病组(80例)和非凝血病组(20例)。比较凝血病组和非凝血病组患者收住后第1个24 h的急性生理和慢性健康评分(acute physiology and chronic health evaluation II，APACHE II)、创伤严重程度评分(injury severity score，ISS)、低体温及低灌注发生率等指标。采用Logistic多因素回归方法分析严重创伤患者发生创伤性凝血病的相关因素。将80例创伤性凝血病患者随机分为观察组(40例)和对照组(40例)。对照组按照常规诊疗措施治疗，观察组在对照组处理基础上给予人FIB，比较治疗前后观察组和对照组的凝血功能指标，及治疗后的临床用血量、住院时间及病死率。结果:与治疗前相比，治疗后观察组和对照组的凝血酶原时间(prothrombin time，PT)、活化部分凝血活酶时间(activated partial thromboplastin time，APTT)及D-二聚体水平降低(P<0.05)，FIB水平明显升高(P<0.05)。观察组的红细胞(red blood cell，RBC) 输注量、新鲜冰冻血浆(fresh frozen plasma，FFP)输注量、重症加强护理病房(intensive care unit，ICU)时间及病死率均明显低于对照组，差异具有统计学意义(P<0.05)。创伤性凝血病患者PT>18 s(r=0.623，P=0.024)、APTT>60 s(r=0.722，P=0.018)、凝血酶时间(thrombin time，TT)>15 s(r=0.719，P=0.033)与ISS评分呈正相关。碱缺失(base deficit，BD)≥6(OR=3.678，95%CI=1.065～9.417)、格拉斯哥评分(Glasgow coma scale，GCS)≤8(OR=5.299，95%CI=1.122～8.711)和血小板(platelet，PLT)计数(OR=0.982，95%CI=0.971～0.996)是严重创伤患者发生创伤性凝血病的独立预测因素。结论:人FIB可有效改善创伤性凝血病患者的凝血功能，降低病死率、缩短ICU时间，创伤性凝血病与创伤严重程度、合并休克、低体温和重型颅脑损伤存在一定的相关性。     

接轨站设置位置和布置图型的影响因素及其分类

通过对接轨站设置位置和布置图型主要影响因素的分析。按照能够充分反映接轨站作业特点的交接方式。对接轨站所采用的布置图型进行了归纳和分类。     

醇解技术在制备皮革加脂剂方面的研究进展

本文介绍了醇解反应的动力学、影响醇解反应收率的因素以及醇解反应在合成加脂剂方面的应用。     

石油沥青60℃动力粘度测定影响因素的探讨

粘度是表征沥青稠度的一个重要指标。通过论述石油沥青粘度测定法(真空毛细管法)中毛细管的选择、温度、真空度、取样量等对试验结果的影响及试验过程中的其它注意事项,表明了在测定石油沥青的60℃动力粘度时,必须严格按照试验方法的要求进行测定,以保证试验结果的准确性。     

中国火灾与社会经济因素的关系

对中国的火灾统计数据与社会经济数据之间的关系进行了研究，发现中国火灾与社会经济因素的关系和国外相反:中国的火灾形势在经济越发达的地方越严重，并且随着经济的发展更趋严重。讨论了火灾与经济水平及教育水平的关系，提出了火灾和经济的更为全面的关系，即随着经济的发展，火灾形势是先严重后趋缓和。根据所讨论的结果对中国未来一段时期的火灾情况做出了一些预测。     

环境敏感因素对电站正常蓄水位选择的影响

卜寺沟水电站预可阶段正常蓄水位是考虑规划成果、地形、地质务件、梯级衔接、水库淹没、筑坝技术、水能资源利用等因素综合初选的.从理论角度分析,水库淹没时水库内寺庙的影响,按全部淹没进行经济补偿处理代价较小;其社会环境敏感因素对正常蓄水位的选择不应起决定性作用.但是,考虑到少数民族群众、僧侣和地方政府的要求,适当降低正常蓄水位,以减少对扎西日岗寺庙的影响,将带来较积极的社会影响.     

Elimination of organic matter present in wastewaters from the cork industry by membrane filtration

BACKGROUND: The first stage of the cork industrial process generates great volumes of wastewater with moderate to high organic pollutant content that must be purified using different procedures, such as filtration by membranes. RESULTS: The tangential filtration of these wastewaters was studied using two different laboratory equipments. In the first one, three ultrafiltration (UF) membranes were tested, with molecular weight cut‐off (MWCO) 100 kDa and 30 kDa, and two operating modes were used: total recycling of permeate and retentate streams, and in continuous mode, without recycling both streams. In the total recycling UF experiments, the influence of the operating variables on the permeate flux was first established. The effectiveness of the different membranes was determined by evaluating the rejection coefficients for several parameters that measure the global pollutant content of the effluent. The values found for these rejection coefficients were in the following order: ellagic acid and color > absorbance at 254 nm > tannic content > COD (chemical oxygen demand). In the continuous mode experiments, the fouling mechanism for each membrane was established by fitting the experimental data to various filtration fouling models given in the literature. The operating mode in the second equipment was batch concentration, and additional experiments were carried out with an UF membrane (2 kDa), and with a NF membrane (with MWCO in the range 150–300 Da). CONCLUSIONS: The three operating modes tested provided different rejection levels of organic matter; among them, the most effective procedure tested was batch concentration mode using a NF membrane. Copyright © 2007 Society of Chemical Industry