Effects of Neodymium and Calcium on the Thermal Stability of AZ71 Magnesium Alloys

The effects of an addition of 0–2 wt% Nd on thermal stability of 0–3 wt% Ca-containing modified AZ71 magnesium alloys was investigated. The ignition temperature was found to increase from that of AZ71, 574, to 825 °C with the addition of 0.5 wt% Ca and 1 wt% Nd. The ignition temperature was further increased to 1114 °C when 3 wt% Ca was added. The Ca- and Nd-added AZ71 was isothermally maintained at a temperature of 500 °C in air for 12 h. The MgO–CaO–Nd₂O₃ formed on the surface to improve the thermal stability of the AZ71–xCa–yNd alloys. While both the tensile strength and ductility decreased with the Ca concentration in the alloy, an addition of 1 wt% Nd was found able to alleviate the degradation effects of Ca on the tensile strength and ductility at 170 °C. Both solid solution formation and precipitation strengthening contributed to the increase in toughness. AZ71 containing 0.5–2 wt% Ca and 1 wt% Nd provides the optimum combination of ignition resistance and mechanical properties.     

A comparison study of Taiwanese He-Yuan Architecture between the ethically spatial order and the condition of physical environment

Since the 21st century, problems such as global warming and energy depletion have become important issues to scientists and architects. The architectural design nowadays often relies on large amount of mechanical equipment to create a comfortable environment for the users. However, it burdens and deteriorates the nature. On the other hand, some of the traditional architecture in the past can cope with the local humid and hot climate, achieving good passive heat control for the environment. Therefore, this study explores the relation between traditional residents in Taiwan’s use of space and the external environment and climate through modern environment measurement technique, restores and conducts quantitative analysis on the interior thermal environment and light environment of Lin-An-Tai Historical House in the past through Ecotect Analysis, and analyzes the results of the calculation in terms of its spatial allocation, openings, and outer walls, etc. This study also evaluates the effects of lighting and user’s sense of comfortable temperature under its environmental conditions according to the standards of residential quality nowadays. It further studies the ancestor of traditional architecture by reviewing its spatial order and compares to the current situation in order to feedback the modern architecture design. Part of the results of the simulation show that the variation of temperature indoors in each space is less dynamic than that of outdoors. The temperature in the space at the right of the main hall (northwestern side) is generally higher than that in the left (southeastern side). The highest temperature in the space farther away from the interior patio is usually higher than that in the space closer to the interior patio. The temperature near the outer side of the space above Hulong is higher than that in the middle. Accordingly, the location is closely related to the interior temperature. As to human’s sense of comfortable temperature, the results show that in summer, the Predicted Mean Vote (PMV) in the space at the left of the main hall (southeastern side) is generally higher than that in the right (northwestern side). In winter, the sense of comfortable temperature in the rooms in the corner is lower than that in other rooms at the inner side, the comparison between the space ethical order and the evaluation result did not show any obvious relationship. For the evaluation of lighting, the main hall and the restaurant at the outer left Hulong have better lighting while other space does not have sufficient and even lighting. Artificial lighting is needed to make the space more functional, the results shows that lighting conditions of space did not metaphor to the space ethical order.     

Why do people purchase virtual goods? A uses and gratification (U&G) theory perspective

Few literature studies have investigated the relationships between different uses and gratifications (U&Gs) of mobile instant messaging (MIM) apps, continuation, and purchase intentions. To address this gap, the researchers aimed to examine the influence of the content, social, process, and technology U&Gs of MIM on continuation intentions toward MIMs, and purchase intentions toward virtual goods available on MIMs. A comprehensive research model was developed based on the U&G theory, which was tested using cross-sectional data from 309 Japanese MIM users. The study considered six different U&Gs of MIM as independent variables and purchase intentions towards stickers and continuation intentions towards MIM as dependent variables. The study results suggest that exposure U&G has a significant positive association with MIM sticker purchase intentions. The entertainment and affection U&G are positively associated with continuation intentions towards MIM use. The study contributes to the literature by investigating U&Gs that motivate MIM users to have both positive purchase intentions toward virtual goods, such as stickers, and continuation intentions toward MIMs. The study has significant theoretical and practical implications for both researchers and practitioners who are interested in virtual goods, the virtual economy, MIM apps, social media, new media, and the service economy.     

Governance choices and policy outcomes in the Latin American and caribbean electricity sector

The paper first provides, for Latin America and the Caribbean, country-specific synthetic quantitative measures of the degree of adoption of governance reforms in the electricity sector, focusing on four key dimensions (market structure, private sector participation (PSP), regulatory autonomy and operational organization). These measures are then correlated with standard policy performance outcomes measures. The findings suggest that, the reforms, considered jointly, were statistically significantly associated with higher technical and process quality but not with social or service improvements. Considered individually, increased regulatory autonomy enjoyed the highest positive correlation with desirable outcomes, but PSP has no significant correlation with any of the outcomes. In sum, as of 2018, governance reforms, considered jointly, had still not delivered on some promised payoffs, notably in addressing energy poverty, although the sensitivity analysis suggests that, for some indicators, the relationships are stronger for larger than for smaller countries.     

Collective reflection strategy for moderating conformity tendency and promoting reflective judgment performance

Reflective judgement is crucial for medical-related practitioners in dealing with controversial issues. However, the conformity phenomenon is likely to occur and interfere with reflective judgement learning during interactive activities. Effective strategies are required to moderate the conformity behaviour tendency (CBT) and improve reflective judgement performance (RJP). This study demonstrates two significant results: (a) Compared with the guided self-reflection learning strategy, the online collective reflection (OCR) learning strategy effectively weakened the learners' general CBT while dealing with professional controversial issues; and (b) a significantly negative correlation between the RJP achieved and the change of CBT in online environment was detected in the OCR group. The implications and potential applications in higher education were discussed. Further studies are needed to confirm the long-term effects and the extending application to other professional studies.     

Effect of resiliency and age on musculoskeletal injuries and lost workdays in emergency medical service personnel

Emergency medical service (EMS) personnel are highly skilled health care professionals who often provide lifesaving clinical care to patients. Paradoxically, they may be repeatedly exposed to a unique set of occupational hazards that could endanger their own health. This cross-sectional study sought to examine the relation between resiliency and musculoskeletal injuries (MSIs) and between resiliency and lost workdays due to MSIs, and explore whether age modifies these associations. Multivariable Poisson main effects regression models showed that resiliency had a protective effect against MSIs, but not lost workdays. In the unadjusted regression model to evaluate the relation between resiliency and age, results suggested that no differences in distributions existed between younger and older EMS personnel and resiliency. However, given the same unit increase in resiliency, findings from multivariable Poisson interaction regression models indicated that older workers had a higher prevalence of MSIs and lost workdays than younger workers. Results from main effects models may reflect diverging routes on a pathophysiological pathway, in which resiliency acts as a prognostic factor for MSIs but not lost workdays. Findings might also indicate the association between resiliency, and MSIs and lost workdays varies by age.Relevance to industryThe largest growth of labor in the US is expected to occur in the oldest segments of the population. While older workers may offer more experience and show similar resiliency to younger workers, they might be more vulnerable to individual risk factors and occupational exposures. If management wants to retain older workers as assets, they should design the work environment to match the capabilities of all workers.     

Investigation on low-temperature sintered AlN nanoceramics with high thermal conductivity

The aim of this research was to investigate the effect of sintering additive and relatively low-sintering temperature on the thermal conductivity of aluminum nitride nanoceramic. While using nanosized AlN powder and liquid-phase sintering additives, the various sintering processes were performed at temperatures 1400 and 1500°C for several hours. In the analysis methods, thermal conductivity (K) and thermal diffusivity (α) were measured using thermal conductivity analyzer (Hot Disk), scanning electron microscope (SEM) was used to observe the surface morphology of the microstructure, x-ray diffraction analyzer (XRD) to analyze the grain size and crystal structure, Raman spectroscopy (Raman) emission spectrum was analyzed to identify the material microstructure and the densities of AlN specimens were measured by Archimedes method. It was found that the thermal conductivity is related to the densification of nanosize low-temperature sintered material, which can be controlled by additives and sintering temperature. With Y₂O₃ sintering add, the densification of AlN for low-temperature sintering increased by the factor of ～5% to ～12%, and the thermal conductivity was enhanced by 25%. The relative density observed in this research is about 78%-84%, and the thermal conductivity measured is in the range of 9-14 W/mK.     

Comprehensiveness and uniqueness of commercial databases and open access systems

Scientometrics - In this study, scholarly communication systems provided by commercial services and open access systems are examined on the basis of the comprehensiveness and uniqueness of their...     

A similarity hybrid harmony search algorithm for the Team Orienteering Problem

The Harmony Search (HS) is a metaheuristic algorithm, which is inspired from the composition of music harmonies. The functionality and flexibility of HS contribute to the development of successful methodologies for different kind of scientific problems. The aim of this paper is to propose a variant of the classic HS algorithm in order to provide competitive solutions for the Team Orienteering Problem (TOP). We introduce the Similarity Hybrid Harmony Search (SHHS) algorithm as an alternative and innovative optimization method. The SHHS follows the standard procedure of HS with some modifications and includes a new strategy called “similarity process”. Two versions of the proposed method have been developed, the static version with predefined values for the parameters of the method and the dynamic one with dynamic adjustment of the parameters. The SHHS algorithm is applied to the known benchmark instances of TOP. The dynamic of the algorithm is tested through a complete solution analysis which gives the superiority of the dynamic version compared to the static one. The results of both versions of the proposed algorithm indicate the positive performance against other effective and robust optimization algorithms from the literature.