Thermal reliabilities of Sn-0.5Ag-0.7Cu-0.1Al2O3/Cu solder joint

The effects of trace addition of Al₂O₃ nanoparticles (NPs) on thermal reliabilities of Sn-0.5Ag-0.7Cu/Cu solder joints were investigated. Experimental results showed that trace addition of Al₂O₃ NPs could increase the isotheraml aging (IA) and thermal cyclic (TC) lifetimes of Sn-0.5Ag-0.7Cu/Cu joint from 662 to 787 h, and from 1597 to 1824 cycles, respectively. Also, trace addition of Al₂O₃ NPs could slow down the shear force reduction of solder joint during thermal services, which was attributed to the pinning effect of Al₂O₃ NPs on hindering the growth of grains and interfacial intermetallic compounds (IMCs). Theoretically, the growth coefficients of interfacial IMCs in IA process were calculated to be decreased from 1.61×10^-10 to 0.79×10^-10 cm²/h in IA process, and from 0.92×10^-10 to 0.53×10^-10 cm²/h in TC process. This indicated that trace addition of Al₂O₃ NPs can improve both IA and TC reliabilities of Sn-0.5Ag- 0.7Cu/Cu joint, and a little more obvious in IA reliability.     

Data fusion and transfer learning empowered granular trust evaluation for Internet of Things

In the Internet of Things (IoT), a huge amount of valuable data is generated by various IoT applications. As the IoT technologies become more complex, the attack methods are more diversified and can cause serious damages. Thus, establishing a secure IoT network based on user trust evaluation to defend against security threats and ensure the reliability of data source of collected data have become urgent issues, in this paper, a Data Fusion and transfer learning empowered granular Trust Evaluation mechanism (DFTE) is proposed to address the above challenges. Specifically, to meet the granularity demands of trust evaluation, time–space empowered fine/coarse grained trust evaluation models are built utilizing deep transfer learning algorithms based on data fusion. Moreover, to prevent privacy leakage and task sabotage, a dynamic reward and punishment mechanism is developed to encourage honest users by dynamically adjusting the scale of reward or punishment and accurately evaluating users’ trusts. The extensive experiments show that: (i) the proposed DFTE achieves high accuracy of trust evaluation under different granular demands through efficient data fusion; (ii) DFTE performs excellently in participation rate and data reliability.     

贵州北盘江增殖放流效果评价

为了评估北盘江鱼类增殖放流效果,2017~2018年期间采用体外荧光、剪鳍、"T"型标三种标志方法对目标鱼类进行标志放流,通过集中捕捞方式进行回捕调查,集中捕捞时间为2017年7月、2018年8月,捕捞水域为董菁-马马崖-光照-善泥坡库区。结果表明,白甲鱼回捕率较高,为0.82%,其他鱼类均在0.5%左右,其中主要为低龄鱼类,高龄鱼类较少;董菁打邦河及各库尾水域物种丰富度较高,善泥坡高家渡码头和马马崖库区试验库尾物种多样性指数相对较低。建议在以后的增殖放流活动中,加大每年的监测频次。     

KL油田明化镇组富砂型沉积储层特征研究

KL油田的主要含油层系为新近系明化镇组,砂岩含量高,储层发育,叠置连片分布,表现为"富砂"的沉积特征,地震资料品质不支持进行常规的单砂体描述。基于岩心、分析化验、测井曲线等资料,对KL油田明化镇组储层岩性特征、孔隙特征及物性特征进行分析,认为明化镇组储层为浅水三角洲沉积,储层具有特高孔、特高渗的特征。根据地震相特征,并结合沉积相和测井相,按储层发育特征将研究区储层分为三类,并提取振幅属性,刻画出砂体边界,对储量进行了重新认识。研究结果对油田开发方案的编制以及后期的生产调整具有重要意义。     

Nonvolatile taste components,nutritional values,bioactive compounds and antioxidant activities of three wild Chanterelle mushrooms

The chemical compositions, nonvolatile taste components and nutritional compounds of three wild edible Chanterelle mushrooms (C. cibarius Fr (CcF), C. cinnabarinus schwein (CcS) and C. tubaeformis Fr (CtF)) were evaluated. Results showed Chanterelle mushrooms were good sources of proteins and carbohydrates with low energy. CcS was rich in trehalose in free sugars and glucose in soluble sugars. Monosodium glutamate‐like free amino acids and flavour 5′‐nucleotides indicated Chanterelle mushrooms had good taste. Based on their amino acids compositions and nutrition evaluations, CcF, CcS and CtF were significant sources of amino acids and protein. CtF showed better protein quality than CcF and CcS. Stearic and oleic acids showed high contents in three mushrooms, and higher unsaturated fatty acids were found in CcF. Three mushrooms had high contents of K, Ca and Mg, and low content of Na. Organic acid and phenolic acids of three mushrooms were identified, and antioxidant activities were evaluated.     

Reliability of design approaches for axially loaded offshore piles and its consequences with respect to the North Sea

In the near future, several offshore wind farms are planned to be built in the North Sea. Therefore, jacket and tripod constructions with mainly axially loaded piles are suitable as support structures. The current design of axial bearing resistance of these piles leads to deviant results regarding the pile resistance when different design methods are adopted. Hence, a strong deviation regarding the required pile length must be addressed. The reliability of a design method can be evaluated based on a model error which describes the quality of the considered design method by comparing measured and predicted pile bearing resistances. However, only few pile load tests are reported with regard to the boundary conditions in the North Sea. This paper presents 6 large-scale axial pile load tests which were incorporated within a new model error approach for the current design methods used for the axial bearing resistance, namely API Main Text method and cone penetration test (CPT)-based design methods, such as simplified ICP-05, offshore UWA-05, Fugro-05 and NGI-05 methods. Based on these new model errors, a reliability-based study towards the safety was conducted by performing a Monte-Carlo simulation. In addition, consequences regarding the deterministic pile design in terms of quality factors were evaluated. It is shown that the current global safety factor (GSF) prescribed and the partial safety factors are only valid for the API Main Text and the offshore UWA-05 design methods; whereas for the simplified ICP-05, Fugro-05 and NGI-05 design methods, an increase in the required embedded pile length and thus in the GSF up to 2.69, 2.95 and 3.27, respectively, should be considered to satisfy the desired safety level according to DIN EN 1990 of β = 3.8. Further, quality factors for each design method on the basis of all reliability-based design results were derived. Hence, evaluation of each design method regarding the reliability of the pile capacity prediction is possible.     

Quantitative relationship between time margin and human reliability

Operator reliability in complex systems is influenced by various performance shaping factors (PSFs). Time is a particularly important PSF; however, empirical studies of human reliability analysis (HRA) are rarely focused on modeling the effect of time PSF on human error probability (HEP). This study contributes to HRA literature by investigating the empirical relationship between time margin and HEP. Time margin is defined as the difference between the time available to complete a task and the time required to successfully complete the task, divided by the required time. We investigate and compare two models (logistic and linear) to explain HEP based on time margin. The empirical HEP data for model testing were extracted from a microworld simulator (Study 1) and a full-scope simulator (Study 2) in two existing studies relevant to procedural tasks in nuclear power plants. For Study 1, both models exhibited an acceptable, equivalent explanatory power; for Study 2, although both models exhibited an acceptable explanatory ability, the logistic model explained more variance in HEP. Our findings indicate the potential of the logistic model in explaining and predicting HEP based on time margin in time-critical tasks.     

湾图沟煤矿高强度采动巷道稳定性评价研究

针对高强度采动巷道围岩控制难题，从实验室岩样尺度和现场巷道尺度研究了湾图沟煤矿13405工作面回风平巷围岩稳定性特征。结合单轴压缩试验和声波测试分析了干燥、自然及饱和状态下3组岩样的力学行为差异特征。利用钻孔成像，分析了高强度采动影响巷道围岩裂隙发育分段特征。结果表明:干燥、自然及饱和状态下岩样的单轴抗压强度和弹性模量依次降低，水分的存在极大地降低了岩石的强度和刚度。实煤体段围岩仅在深度1 m范围内发现少量纵向裂隙。高静压段两帮维护效果较差，煤帮裂隙极为发育，存在高量值的离层。动压段巷道顶板完整性较好，两帮均发现较大离层，且超出了锚杆正常锚固范围，严重影响了巷道锚固结构的稳定性。     

招远市金矿资源开发利用调查评价研究

为深入贯彻生态文明思想，促进矿产资源全面节约和高效利用，对招远市展开了金矿矿产资源开发利用水平调查评价，对2018年度数据进行整理和实地核查后，进行了单个矿山评价和多矿山评价，包括矿种评价、地区评价、行业评价。招远市16个矿山实际数据和基准值指标对比显示，单个矿山评价和多矿山评价的达标率均为100%。在此基础上，分析了金矿矿产资源资源开发利用水平调查评价的意义和存在问题。     

国际环境不确定下海外采矿权评估研究

在实物期权理论框架下,基于Black-Schole采矿权评估模型,提出了计量国际环境不确定性的方法以及将其纳入评估模型的途径,以此优化完善海外采矿权评估; 通过一实例验证了本文所述方法的可行性,并依据评估结果进一步分析了投资策略,最后对所提方法的可靠性进行了检验。研究结果显示: ① 采矿权价值来自于矿业权人对矿产资源的开采加工及具有灵活经营的权利,国际环境的不确定变化影响采矿权价值及投资策略。② 矿产品价格升高、价格波动率增加、驻在国矿业行业环境和国家环境变异程度的增加、矿山服务年限的增加,均提高了海外采矿权价值; 但矿产品价格下降、矿山服务年限减少将降低采矿权价值。③ 当矿产品价格持续处于低位时,项目应尽早建设或放弃; 而当价格处于增长或高位时,项目可适当推迟建设。④ 老挝矿业行业环境的变异程度大于该国国家环境的变异程度,前往老挝投资的矿企应重点关注该国涉及矿业投资的法律法规及政策,重点防范行业风险。⑤ 本文所提海外采矿权评估方法是可行、可靠的,具有一定实践意义。