• Energy Research
• 2021-2025close
• engineering and technology close
• MX close

Frozen food is exposed to inevitable temperature changes during its storage, transport, and at the point of sale, which implies a significant impact on its properties and quality. Thus, the study of the effect of the formation of crystals on both the surface of the meat and the container when it is kept frozen, involving the thermodynamic analysis and changes that occurred at the structural level, is necessary. In this research, pork meat from Longissimus thoracis muscle was used, which was cut into plates and packed with two types of food-grade films: (1) Polyvinyl Chloride (PVC) and (2) low-density polyethylene (LDPE). Samples were frozen by indirect contact with nitrogen up to −40 ± 0.5 °C and subsequently stored at −20 ± 1 °C in a chamber from 0 to 15 days. The frost thickness was evaluated by the image superposition method. FTIR spectra were obtained by means of an Attenuated Total Reflectance (ATR) accessory, and thermal changes were determined by Modulated Differential Scanning Calorimetry (MDSC). It was found that the thickness of the frost on the surface of the meat is less when it is packaged with PVC due to the characteristics of the polymer matrix of the package. Furthermore, there were important changes at the molecular level identified by FTIR and MDSC, indicating significant differences (p < 0.05) between the samples. In general, PVC films were more stable at lower temperatures, allowing a small number of changes in the meat surface due to temperature fluctuations.

The Analysis and Optimization in Micro-hydro-generation is the best way to improve new renewable systems. As is known, the Micro-hydroelectric generation is an alternative in areas that has zero access to electrical energy, or isolated areas. The objective of this paper, is to show how a methodology could improve the behavior in the hydroelectric generation. In this case, is based on design considerations by Bilal Abdullah. This paper is about an specific test bench installed in Chiapas, with flow conditions from 4 to 16 l/min, the flow considerations are presented in a new scheme, that is proposed in a previous work made by us. In this specific case, includes the evaluation of the flow due to a tank that is installed in the evaluation area, and the mathematical models are adapted to this case.

Les développements des systèmes de transport, les changements dans les tendances de consommation et des conditions telles que la COVID-19 ont augmenté à la fois la demande et la charge du transport de marchandises. Étant donné que diverses entreprises transportent des marchandises dans le monde entier pour évaluer la durabilité, la vitesse et la résilience des systèmes de transport de marchandises, des systèmes de mesure de la fluidité des données et du fret sont nécessaires. Dans cette étude, un modèle de prise de décision intégré est proposé pour donner la priorité aux alternatives de mesure de la fluidité du fret. Le modèle proposé est composé de deux étapes principales. Dans la première étape, la méthodologie logarithmique des poids additifs (LMAW) basée sur les normes de Dombi est utilisée pour trouver les poids des critères. Dans la deuxième phase, une évaluation étendue basée sur la méthode de la distance de la solution moyenne (EDAS) avec Dombi onction pour l'agrégation est présentée pour déterminer les résultats finaux de classement des alternatives. Trois alternatives de mesure de la fluidité du fret sont proposées, à savoir ne rien faire, intégrer les activités de fret dans Metaverse pour mesurer la fluidité et former une gouvernance mondiale des activités de fret pour mesurer la fluidité à partir des données disponibles. Treize critères, qui sont regroupés sous quatre aspects principaux à savoir la technologie, la gouvernance, l'efficacité et la durabilité environnementale, et une étude de cas au cours de laquelle un cadre de base est formé pour que les experts évaluent les alternatives compte tenu des critères utilisés dans le processus décisionnel multicritères. Les résultats de l'étude indiquent que l'intégration des activités de fret dans Metaverse pour mesurer la fluidité est l'alternative la plus avantageuse, alors que ne rien faire est la moins avantageuse. Los desarrollos en los sistemas de transporte, los cambios en las tendencias de consumismo y condiciones como el COVID-19 han aumentado tanto la demanda como la carga en el transporte de mercancías. Dado que varias empresas transportan mercancías en todo el mundo para evaluar la sostenibilidad, la velocidad y la resistencia de los sistemas de transporte de mercancías, se necesitan sistemas de medición de datos y fluidez de la carga. En este estudio, se propone un modelo integrado de toma de decisiones para priorizar las alternativas de medición de la fluidez de la carga. El modelo propuesto se compone de dos etapas principales. En la primera etapa, se utiliza la Metodología Logarítmica de Pesos Aditivos (LMAW) basada en normas Dombi para encontrar los pesos de los criterios. En la segunda fase, se presenta una Evaluación extendida basada en el método de Distancia de la Solución Media (EDAS) con Dombi unción para la agregación para determinar los resultados finales de clasificación de las alternativas. Se proponen tres alternativas de medición de la fluidez de la carga, a saber, no hacer nada, integrar las actividades de carga en Metaverse para medir la fluidez y formar una gobernanza global de las actividades de carga para medir la fluidez a través de los datos disponibles. Trece criterios, que se agrupan en cuatro aspectos principales: tecnología, gobernanza, eficiencia y sostenibilidad ambiental, y un estudio de caso en el que se forma un marco básico para que los expertos evalúen las alternativas considerando que los criterios se utilizan en el proceso de toma de decisiones multicriterio. Los resultados del estudio indican que integrar las actividades de carga en Metaverso para medir la fluidez es la alternativa más ventajosa, mientras que no hacer nada es la menos ventajosa. Developments in transportation systems, changes in consumerism trends, and conditions such as COVID-19 have increased both the demand and the load on freight transportation. Since various companies are transporting goods all over the world to evaluate the sustainability, speed, and resiliency of freight transportation systems, data and freight fluidity measurement systems are needed. In this study, an integrated decision-making model is proposed to advantage prioritize the freight fluidity measurement alternatives. The proposed model is composed of two main stages. In the first stage, the Dombi norms based Logarithmic Methodology of Additive Weights (LMAW) is used to find the weights of criteria. In the second phase, an extended Evaluation based on the Distance from Average Solution (EDAS) method with Dombi unction for aggregation is presented to determine the final ranking results of alternatives. Three freight fluidity measurement alternatives are proposed, namely doing nothing, integrating freight activities into Metaverse for measuring fluidity, and forming global governance of freight activities for measuring fluidity through available data. Thirteen criteria, which are grouped under four main aspects namely technology, governance, efficiency, and environmental sustainability, and a case study at which a ground framework is formed for the experts to evaluate the alternatives considering the criteria are used in the multi-criteria decision-making process. The results of the study indicate that integrating freight activities into Metaverse for measuring fluidity is the most advantageous alternative, whereas doing nothing is the least advantageous one. أدت التطورات في أنظمة النقل، والتغيرات في اتجاهات النزعة الاستهلاكية، وظروف مثل COVID -19 إلى زيادة الطلب والحمل على نقل البضائع. نظرًا لأن العديد من الشركات تنقل البضائع في جميع أنحاء العالم لتقييم استدامة وسرعة ومرونة أنظمة نقل البضائع، فهناك حاجة إلى أنظمة قياس سيولة البيانات والشحن. في هذه الدراسة، يُقترح نموذج متكامل لصنع القرار للاستفادة من إعطاء الأولوية لبدائل قياس سيولة الشحن. يتكون النموذج المقترح من مرحلتين رئيسيتين. في المرحلة الأولى، يتم استخدام منهجية لوغاريتمية الأوزان المضافة (LMAW) القائمة على معايير دومبي لإيجاد أوزان المعايير. في المرحلة الثانية، يتم تقديم تقييم موسع يعتمد على طريقة المسافة من الحل المتوسط (EDAS) مع Dombi unction للتجميع لتحديد نتائج الترتيب النهائي للبدائل. يتم اقتراح ثلاثة بدائل لقياس سيولة الشحن، وهي عدم القيام بأي شيء، ودمج أنشطة الشحن في ميتافيرس لقياس السيولة، وتشكيل حوكمة عالمية لأنشطة الشحن لقياس السيولة من خلال البيانات المتاحة. ثلاثة عشر معيارًا، تم تجميعها تحت أربعة جوانب رئيسية وهي التكنولوجيا والحوكمة والكفاءة والاستدامة البيئية، ودراسة حالة يتم فيها تشكيل إطار أرضي للخبراء لتقييم البدائل مع مراعاة استخدام المعايير في عملية صنع القرار متعددة المعايير. تشير نتائج الدراسة إلى أن دمج أنشطة الشحن في ميتافيرس لقياس السيولة هو البديل الأكثر فائدة، في حين أن عدم القيام بأي شيء هو البديل الأقل فائدة.

This paper presents a novel single-phase (SP) active-neutral point clamped (ANPC) five-level bidirectional converter (FLBC) for enhancing the power quality (PQ) during the grid-to-vehicle (G2V) and vehicle-to-grid (V2G) operation of an electric vehicle (EV) charger connected in series. This EV charger is based on a dual-active half-bridge DC-DC converter (DAHBC) with a high frequency isolation transformer. Unlike the comparable ANPC topologies found in literature, the proposed one has two more switches, i.e., ten instead of eight. However, with the addition of these components, the proposed multilevel converter not only becomes capable of properly balancing the voltage of the DC-link split capacitors under various step-changing conditions but it achieves a better efficiency, a lower stress of the switching devices and a more even distribution of the power losses. The resulting grid-tied ANPC-SPFLBC and DAHBC are accurately controlled with a cascaded control strategy and a single-phase shift (SPS) control technique, respectively. The simulation results obtained with MATLAB-SimPowerSystems as well as the experimental results obtained in laboratory validate the proposed ANPC-SPFLBC for a set of exhaustive tests in both V2G and G2V modes. A detailed power quality analysis carried out with a Fluke 43B alike demonstrates the good performance of the proposed topology.

The fermentation of syngas is an attractive technology that can be integrated with gasification of lignocellulosic biomass. The coupling of these two technologies allows for treating a great variety of raw materials. Lignin usually hinders microbial fermentations; thus, the thermal decomposition of the whole material into small molecules allows for the production of fuels and other types of molecules using syngas as substrate, a process performed at mild conditions. Syngas contains mainly hydrogen, carbon monoxide and carbon dioxide in varying proportions. These gases have a low volumetric energy density, resulting more interesting its conversion into higher energy density molecules. Syngas can be transformed by microorganisms, thus avoiding the use of expensive catalysts, which may be subject to poisoning. However, the fermentation is not free of suffering from inhibitory problems. The presence of trace components in syngas may cause a decrease in fermentation yields or cause a complete cessation of bacteria growth. The presence of tar and hydrogen cyanide are just examples of this fermentation&#039;s challenges. Syngas cleaning impairs significant restrictions in technology deployment. The technology may seem promising, but it is still far from large-scale application due to several aspects that still need to find a practical solution.

Recycling and remanufacturing waste electrical and electronic equipment (WEEE) can promote the comprehensive utilization of resources and promote the development of the circular economy. However, there are associated risks involved. This study explored the effectiveness of risk control in the WEEE closed-loop supply chain to provide decision support in the sustainable development of WEEE. The catastrophe progression method was used for risk evaluation, and the WEEE risk control model was constructed using system dynamics to analyze the influence of risk control strategies. The results show that adopting risk control strategies positively promotes risk control. Risk mitigation is most pronounced when both the fund subsidy and the green and low-carbon strategies are adopted. When only one approach is implemented, the green and low-carbon strategy has a more considerable effect. When the intensities of the mitigation measures are improved to the same extent, the risk control effect generated by the fund subsidy strategy was found to have a greater impact. The findings provide a useful reference for formulating subsequent risk control strategies in the WEEE closed-loop supply chain.