Performance of an oil-free linear compressor using R1234yf

As an alternative to the hydrocarbons (HCs), R1234yf synthetic refrigerant from the family of the hydrofluoroolefins (HFOs), has emerged recently as a replacement fluid for R134a. The purpose of this study is to investigate the performance of an oil-free linear compressor using R1234yf operated at different pressure ratios for household refrigerators. A mathematical model for the oil-free linear compressor using R1234yf has been developed. The compressor stroke was set as 14 mm for minimum dead volume with the evaporator temperature of – 23 °C. The result shows that the bleed flow rate can be 5% of main flow rate, and the resonant frequency varies between 32.7 Hz and 35.3 Hz for pressure ratios of 5-12. Cylinder mean pressure, shaft power, bleed flow, and clearance seal power loss increase with the pressure ratio. At pressure ratio of 10, and clearance seal power loss represents 8% of shaft power

An Empirical Investigation on the Role of exports, imports and its Determinants in Foreign Trade of Pakistan

Abstract: Foreign trade was restrained by fluctuations and depreciations in currencies, nations were under financial pressure to implement protection measures in form of custom duties tariffs. These theories and thoughts have enormous impact on rules and policies of global trade throughout the world. To adopt economic liberalization and free trade zones nations all over the world are connected through number of agreements since last few centuries. In this revolutionized economic system, nations allow free trading of merchandise and services and at the same time don't have to impose tariff in form of import and exports duties. This study attempted to empirically evaluate the role of imports, exports and its determinants in foreign trade of Pakistan applied ARDL Approach for the period of 1972-2015. The study recommends that economies with significant competitiveness and comparative advantage will be greatly benefited from export promoting policies. As far as trade partners are concerned, no considerable efforts have been done to explore new markets in direction of Pakistan's foreign trade since its independence. The key trading partners of Pakistan in the beginning were the developed countries of West and still they are main trading partners of Pakistan

Numerical Modeling of Flood Control System in the Middle Yangtze River by Coupled Hydrological-Hydrodynamic Approach

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Development of NCOVID-19 Colloidal Gold Immunochromatographic Test Strip

Purpose: To establish a fast, simple and accurate method and immunoassay test card for the detection of new coronavirus (nCOVID-19) antigen. Methods: In this study, colloidal gold immunochromatography technology was used to detect nCOVID-19 virus antigens through the sandwich method. At the same time, the preparation plan of colloidal gold was improved, and the application of rapid immune-diagnosis technology in other fields was developed. In this study, purified recombinant nCOVID-19 nucleocapsid protein is used as the antigen to prepare murine monoclonal antibodies. The BN02 antibody produced by the mouse is used as the detection antibody to couple with colloidal gold, forming a gold-labeled complex probe. BN9m1 is used as the coating antibody for the C-line, and ProA is used for the T-line. The polymerization of colloidal gold particles enables us to detect the new coronavirus antigen’s appearance. Thus an in vitro rapid detection kit for virus detection can be made. Results: The positive detection rate of the antigen quality control serum with this colloidal gold reagent was 100%. The specificity was 100%, and the sensitivity was 1ng/ml.  Conclusion: The nCOVID-19 antigen detection reagent (colloidal gold method) developed in this research has high specificity and sensitivity, and can be used in conjunction with nucleic acid detection. As a means of detecting nCOVID-19, it can achieve qualitative and rapid screening of samples with advantage such as accuracy, repeatability, and low cost

Capital Formation, Energy Consumption and Economic Growth in Brazil: An ARDL Bound Testing Approach and Granger Causality

This study analyses the short and long run impact of trade, energy consumption and capital formation on economic growth in Brazil. The time series considered is from the period of 1970-2014. By employing ARDL bound testing approach, the long and short run effects are estimated. With Error Correction model, the findings provide that gross capital formation and energy consumption has established a long run relationship with economic growth. In short run, though slightly but exports, along with energy consumption and capital formation are positively related with economic growth in Brazil. The results of granger causality exhibit a weak but bidirectional causality between gross capital formation and economic growth whereas, gross capital formation and economic growth are unidirectional granger causing energy consumption respectively. The study implies that policy makers need to increase the efficacy of energy sector promoting economic growth. Since the exports of the country are found non-significant in long run, it is important for the country to channelize the capital formation and energy sector within the country enhancing exports to evade from trade deficits. DOI: 10.7176/JESD/10-14-03 Publication date:July 31st 201

Improving garment thermal insulation property by combining two non-contact measuring tools

To investigate the effect of air gaps on the heat transfer performance of clothing, the method using the combination of two non-contact measuring tools (infrared thermal camera and 3D body scanner) has been developed considering the quantification of the air gap thickness and clothing surface temperature of different body parts without contacting clothing surface directly. The results show that the air gaps over middle and lower back of upper body have the largest thickness in all body parts, while the front and back shoulders have the smallest air gap thickness. The one-way analysis of variance shows that air gap thickness under shoulder segments has no significant difference in terms of size. Furthermore, clothing surface temperatures of shoulder and chest decrease gradually along with air gap thickness; clothing surface temperatures of front abdomen, front waist, pelvis and hip segments decrease initially but begin to increase when the air gap is above 1.5cm; clothing surface temperatures of middle back and back waist continually increase with the air gap thickness. Based on the comprehensive analyzation of the distributed features of air gap thickness and clothing surface temperature of different body parts, a revised clothing pattern with lower regional temperature and higher thermal insulation is put forward

Modélisation des glissements de terrain induits par les pluies

Cet article contribue d'abord à un nouveau modèle, qui associe une relation élasto-plastique de contrainte effective-déformation, la loi visqueuse de Bingham, une critère de transition entre les deux, et une relation succion?degré de saturation. Ce modèle permet de décrire le comportement de type solide et fluide des sols non saturés dans un cadre unique. Grâce à la Méthode des Eléments Finis avec des Points d'Intégration Lagrangiens (MEFPIL), qui combine les avantages des approches Lagrangiennes et celles Eulériennes, la formulation rend possible de simuler complètement le comportement des sols non saturés avant et après la rupture, sous conditions aux limites hydromécaniques. Ensuite, un benchmark est montré pour valider ce modèle sous des aspects mécaniques des sols non saturés, et une simulation heuristique pour un glissement de terrain provoqué par la pluie est aussi analysée, les résultats sont validés qualitativement de manière raisonnable. En introduisant la force d'inertie et en améliorant la loi visqueuse, des cas plus réalistes seront ensuite simulés

The Why of Abandonment: Effects of Team Diversity and Leadership Type on the Disbandment and Stagnation of Online Medical Teams

Medical teams (MTs) online could provide more comprehensive and rapid services to patients through the collaboration among physicians. Numerous doctors have participated, but parts of MTs disband or stagnate after a period, so this pressing issue is in need of relief through exploring the reasons. Effects of team diversity, leadership types and their interaction on the team disbandment and stagnation were studied. This study comprehensively examined a sample of 1,071 MTs online, the total MTs on January 10, 2018, and we crawled the data from a leading OHC in China. Logistic regression was utilized. Results revealed team state would be influenced by team diversity and its interaction with leadership type, so the combination pairwise of the leadership and team diversity could reduce the abandonment possibility. Implications in theory and practice about the dealing with the abandonment crisis in online health community, and limitations are discussed

Strategies for lipid production improvement in microalgae as a biodiesel feedstock

In response to the energy crisis, global warming, and climate changes, microalgae have received a great deal of attention as a biofuel feedstock. Due to a high lipid content in microalgal cells, microalgae present as a promising alternative source for the production of biodiesel. Environmental and culturing condition variations can alter lipid production as well as chemical compositions of microalgae. Therefore, application of the strategies to activate lipid accumulation opens the door for lipid overproduction in microalgae. Until now, many original studies regarding the approaches for enhanced microalgal lipid production have been reported in an effort to push forward the production of microalgal biodiesel. However, the current literature demonstrates fragmented information available regarding the strategies for lipid production improvement. From the systematic point of view, the review highlights the main approaches for microalgal lipid accumulation induction to expedite the application of microalgal biodiesel as an alternative to fossil diesel for sustainable environment. Of the several strategies discussed, the one that is most commonly applied is the design of nutrient (e.g., nitrogen, phosphorus, and sulfur) starvation or limitation. Other viable approaches such as light intensity, temperature, carbon dioxide, salinity stress, and metal influence can also achieve enhanced microalgal lipid production.fi=vertaisarvioitu|en=peerReviewed