A modified multi-group model of angular and momentum distribution of cosmic ray muons for thickness measurement and material discrimination of slabs

Muon tomography is a capable imaging technique to measure the geometry of high-Z objects. However,most existed algorithms used in muon tomography have obscured the effects of angular distribution and momentum spectra of cosmic ray muons and reduced the spatial resolution. We present a modified multi-group model that takes into account these effects and calibrates the model by the material of lead. Performance tests establish that the model is capable of measuring the thickness of a Pb slab and identifying the material of an unknown slab on a reasonable exposure timescale, in both cases of complete and incomplete angular data. Results show that the modified multi-group model is helpful for improvements in image resolution in real applications.     

咸潮对氯消毒中三卤甲烷的影响

受咸潮影响的出厂水三卤甲烷比非咸潮时高5倍,其中三溴甲烷增加10~4倍,远远大于三氯甲烷,4种THM8含量顺序发生了倒置,即CHBr_3>CHBr_2Cl>CHBrCl_2>CHCl_3。在管网中咸潮污染的出厂水和未污染水混合,加之余氯的作用,使得管网水中三卤甲烷(THMs)的种类分配再次发生变化。结合国内外的资料,综合评述了咸潮中溴化物与氯的反应及Br-THMs形成的机理,并提出了在咸潮期间控制饮用水中氯化消毒产物的思路。     

环向裂纹缺陷压力管道塑性极限载荷安全性分析

采用正交试验法,编制了25种不同管道尺寸、不同缺陷尺寸的正交实验图,对20号钢管道进行非线性计算。研究了单一载荷及组合载荷下含环向表面裂纹缺陷管道的塑性极限载荷,并用公式计算不同载荷工况下管道的塑性极限载荷,将有限元分析值与理论值进行对比,验证有限元计算的准确性。分析了裂纹环向长度、轴向长度、深度及管径4个因素对塑性极限载荷的影响,从而得到这4个因素对不同载荷工况下管道承载能力的影响规律以及相同裂纹尺寸的管道在不同载荷工况下的等效应力图。     

Heat and moisture transfer in fibrous thermal insulation with tight boundaries and a dynamical boundary temperature

Prefabricated, lightweight building elements are widely used in the building construction sector. Such elements consist of fibrous thermal insulation encapsulated between two metal sheets. Under various circumstances, moisture can appear in the insulation matrix. Since the temperature of the boundary metal sheets changes dynamically with meteorological conditions, heat and mass transfer between boundaries appear in this case. This paper presents a transient model of the heat and mass transfer, including the sorption and condensation processes. A numerical model considers the dynamical changing of the boundary temperatures. A parametric study considering different amplitudes of temperature change, different moisture masses and different thicknesses of the insulation matrix was made. It was found that a relatively small mass of water in the insulation matrix can result in a significantly increased average heat flux during a periodic cycle. The numerical code was verified with experiments, which showed good agreement with the numerics.     

Toward a model of socializing project team members: An integrative approach

Project work is becoming more and more important in everyday business, as is staffing the right newcomers for the project. Recognizing that not all new project team workers possess equally important specific knowledge, skills and abilities for the success of projects, we draw on project management, human resource management, and organizational socialization literature to develop a framework on how new project team members might be socialized, depending on their strategic value for the project. We specifically draw on the socialization tactics literature and propose how four categories of new employees – Internal specialists, External specialists, External generalists and Internal generalists; based on two dimensions – work task complexity and employment mode, can be socialized more effectively. Implications for theory and practice are discussed as well.     

Influence of Ionic Liquid-Based Metal–Organic Hybrid on Thermal Degradation,Flame Retardancy,and Smoke Suppression Properties of Epoxy Resin Composites

A new multifunctional ionic liquid-based metal–organic hybrid (PMAIL) was synthesized by anion exchange between as-synthesized phosphonate-based ionic liquid and phosphomolybdic acid and applied to epoxy resin (EP) as an efficient flame retardant. As expected, with only 1 wt% addition of PMAIL, the char yield of EP-PMAIL1 composite at 700 °C was significantly improved by 108.3% from 12.0% for neat epoxy resin to 25.0%, demonstrating the outstanding catalytic charring effect of PMAIL. Meanwhile, EP-PMAIL6 composite (6 wt% addition) can reach V-0 rating in the UL-94 vertical burning tests easily, and its peak heat release rate and total smoke production of EP-PMAIL6 were dropped by 31.0 and 15.4%, respectively, compared with neat EP. Moreover, the results from cone calorimetry tests showed that the char yield of EP-PMAIL6 was enhanced by 162% from 9.5 to 24.9% compared with neat EP, resulting in a strong intumescent char layer structure with outstanding fire retardance and mechanical properties. The thermo-oxidative stable protective layer retarded the transfer of heat and flammable volatiles during combustion and protected the epoxy matrix from further degradation. In conclusion, our results might provide a new perspective for producing composites with excellent flame retardancy and smoke suppression properties using ionic liquid-based metal–organic hybrid.     

A Novel Approach for Bolted T-Stub Connections

This paper reports an investigation into new connection types and their behaviors determined using full-scale experiments. T-shaped connections were created using the IPE standard profile. The aim of this study was to analyze the influence of T connections based on the IPE standard profile, height of beam to height of T-stub joint (H) of T-stub joints, and lengths (X) of T-stub joints on the behavior of steel connections, in order to provide the necessary data for improving Eurocode 3 and enable efficient use of residue IPE standard profiles and back to the consumption cycle. While the moment resistance values increased with an increase in H from H_min to H_max in model groups with X of 126 mm, and the energy dissipation increased with an increase in H from H_min to H_max and also with an increase in the lengths (X) of T-stub joints from 54 to 126 mm.     

Fast periocular authentication in handheld devices with reduced phase intensive local pattern

To ensure highest security in handheld devices, biometric authentication has emerged as a reliable methodology. Deployment of mobile biometric authentication struggles due to computational complexity. For a fast response from a mobile biometric authentication method, it is desired that the feature extraction and matching should take least time. In this article, the periocular region captured through frontal camera of a mobile device is considered under investigation for its suitability to produce a reduced feature that takes least time for feature extraction and matching. A recently developed feature Phase Intensive Local Pattern (PILP) is subjected to reduction giving birth to a feature termed as Reduced PILP (R-PILP), which yields a matching time speed-up of 1.56 times while the vector is 20% reduced without much loss in authentication accuracy. The same is supported by experiment on four publicly available databases. The performance is also compared with one global feature: Phase Intensive Global Pattern, and three local features: Scale Invariant Feature Transform, Speeded-up Robust Features, and PILP. The amount of reduction can be varied with the requirement of the system. The amount of reduction and the performance of the system bears a trade-off. Proposed R-PILP attempts to make periocular suitable for mobile devices.