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Management is the process that determines the effective running of the business and the prospects for the development of the enterprise. Budgeting is a continuous process that requires constant looking into the future and analyzing. Here are considerable difficulties in the coordination of budgets of individuals. Considering the process of group budgeting, it would first be necessary to improve the flow of information between entities in the group.

AbstractThe current study investigates different methods to minimize the drag coefficient (CD) without ignoring the safety factor related to the stability of a vehicle, i.e., the lift coefficient (CL). The study was carried out by employing an SUV car analyzed numerically using one of the CFD software, Ansys. Four different models such as realizable k–ε, standard k–ω, shear stress transport k–ω, and Reynolds stress model (RSM). The considered models have been validated with experimental data and found in good agreement. The considered inlet velocity varies from 28 to 40 m/s, the results showed that the drag coefficient and the stability are both improved by applying a modification on the roof of the considered car.

Abstract Recently, a number of theoretical and experimental studies have been performed to understand the effect of nanoparticles on thermal properties and heat transfer performance but there is a lack regarding their corrosion properties. In this work, an extended corrosion characterization (at central tower plant storage temperature (565 °C)) has been carried out in two different grades of solar salt (industrial and refined purity) doped with the addition of 1 wt% Al2O3 nanoparticles or 1 wt% SiO2 nanoparticles. Corrosion rates were determined in commercial stainless steel commonly used in CSP technology (347SS) by gravimetric tests, measuring the weight gain during 1000 h, identifying the corrosion products by Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The lowest corrosion rate (0.007 mm/year) was obtained in the refined solar salt with the addition of 1 wt% Al2O3 nanoparticles. A protective layer was formed in the steel-salt interphase, identified through XRD as Al2O3. Additionally, hematite (Fe2O3) and magnetite (Fe3O4) were obtained as unprotective corrosion products throughout the test carried out with or without nanoparticles. In addition, the presence of impurities on the salts generated some stable compounds, as magnesium ferrite (MgFe2O4).

In order to obtain the full impedance characteristics of a lithium-ion capacitor as a function of temperature, the authors proposed the use of dynamic electrochemical impedance spectroscopy. Impedance tests were carried out under wide range of dynamic temperature changes for lithium-ion supercapacitors. Significant differences in electrochemical processes were observed as a result of working temperature. Moreover, the quality of fitting of the equivalent circuits most frequently used in impedance analysis of lithium-ion capacitors was discussed. The proposed methodology allows for a comprehensive characterization of the performance of these devices and provides key information for their optimization in wide range of operations.

This paper deals with experimental investigations of flow boiling in tubular ducts of selected refrigerants—R134a, R507A, and R600a—under near-critical pressures. Near-critical boiling is characterised by low specific enthalpy of evaporation. The positive effect of this feature is the fact that only a small amount of heat consumed by Organic Rankine Cycles is at a constant temperature. This allows a lower terminal temperature of the heating fluid and more effective utilisation of heat sources, especially of low-grade heat sources. The experimental investigations covered a heat flux density of 0.4 to 10 kW/m2 and a mass velocity of 60 to 200 kg/(m2·s). The results of the experimental data were compared to the modified heat transfer correlation of Gungor and Winterton, which provices the best fit for the obtained experimental data. The maximum heat transfer coefficient occurred at the two-phase quality—approximately 0.4 for all the tested fluids under high pressure conditions—which may be thought of as a characteristic feature of the boiling process under near-critical conditions. A modified Gungor–Winterton correlation improves prediction accuracy, especially under the lowest (up to 3 kW/m2) and highest (over 7 kW/m2) heat flux densities for all the tested fluids.

At the outlet of the Vermicelli catchment—a peri-urban area located in the campus of University of Calabria (Cosenza, Southern Italy)—a sedimentation tank is located, aiming at collecting the basin surface runoff and improve its quality. First, experimental results of the treatment effects are here presented and analyzed. In addition, a monitoring campaign was conducted in order to characterize the particles transported by surface runoff and to determine the treatment efficiency of the tank. The analysis showed the presence of a pollutant load in the surface runoff of the Vermicelli basin and provided information on its particle-size distribution (PSD). Results were considered in terms of the treatment efficiency of the sedimentation tank, showing a good overall removal efficiency value, together with a high variability of the removal sedimentation efficiency. This variability is mainly due to the different grain size of the suspended solids and the characteristics of the rainfall event.

This paper presents a DC/AC converter consisting of two two-level inverters. The complex converter is built using two standard three-phase inverters: the main inverter (MI) and the auxiliary one (AI). The MI is controlled in a simple way to generate the stepped output voltage and the AI works as an active filter limiting the higher harmonics in the MI output voltage. The filtering process is based on the orthogonal space vector theory. A development and modification of the basic solution are presented here. The output voltage of the MI takes the shape of a stepped voltage comparable to the voltage generated by multilevel inverters. The AI operates as a very effective active power filter (APF) of the MI output voltage. The AI power is significantly lower in comparison to the MI power.

L'application de systèmes électriques à petite échelle est répandue et l'intégration du contrôle MPPT (Maximum Power Point Tracking) pour les systèmes photovoltaïques avec des applications de batteries améliore encore la faisabilité technico-économique des systèmes renouvelables. À cette fin, un nouveau système de contrôle MPPT utilisant l'algorithme d'optimisation de la coopération basée sur le groupe dynamique (DGBCO) est utilisé pour les systèmes PV. La population de la DGBCO est divisée en groupes d'exploration et d'exploitation. En raison d'une modélisation mathématique efficace, les inconvénients des techniques de contrôle MPPT existantes sont entrepris. Les inconvénients du contrôle MPPT moderne deviennent importants dans des conditions d'ombrage partiel (PSC) qui entraînent une perte de puissance, des fluctuations aléatoires et une action lente du contrôle. Le DGBCO est mis en œuvre à l'aide d'un mécanisme de recherche et de saut qui améliore considérablement les performances du contrôleur MPPT et améliore l'efficacité des systèmes PV. Les résultats sont comparés aux techniques d'optimisation des colonies d'abeilles artificielles (ABC), de l'algorithme de recherche de coucou (CS), de l'optimiseur DragonFly (DFO) et de l'optimisation des essaims de particules (PSO) récemment développées. Les études de cas sur les conditions d'exploitation comprennent une irradiance et un PS à variation rapide avec GM asymétrique. La technique de contrôle MPPT basée sur DGBCO est également validée par la configuration expérimentale. Les résultats sont comparés à l'aide d'indices statistiques et analytiques tels que le temps de suivi, le temps de stabilisation, l'efficacité du suivi de la puissance, l'énergie totale, RMSE, MAE et RE. Les résultats montrent la performance supérieure du DGBCO proposé. Relativement, une récupération d'énergie supérieure de 2 à 8 % et un temps de suivi jusqu'à 60 % plus rapide permettent d'atteindre une efficacité de suivi de la puissance allant jusqu'à 99,86 % en régime transitoire et en régime permanent. Les valeurs inférieures des métriques statistiques, c'est-à-dire RMSE, MAE et SR, indiquent la robustesse et la modélisation mathématique efficace de DGBCO pour une MPPT efficace des systèmes PV dans des conditions PS. La aplicación de sistemas eléctricos a pequeña escala está muy extendida y la integración del control de seguimiento del punto de máxima potencia (MPPT) para sistemas fotovoltaicos con aplicaciones de batería mejora aún más la viabilidad tecnoeconómica de los sistemas renovables. Para este propósito, se utiliza un novedoso sistema de control MPPT que utiliza el algoritmo de optimización de cooperación basada en Dynamic Group (DGBCO) para los sistemas fotovoltaicos. La población en la DGBCO se divide en grupos de exploración y explotación. Debido a la modelización matemática efectiva, se llevan a cabo los inconvenientes de las técnicas de control MPPT existentes. Los inconvenientes del control MPPT moderno se vuelven prominentes bajo condiciones de sombreado parcial (PSC) que dan lugar a pérdida de potencia, fluctuaciones aleatorias y acción de control lenta. El DGBCO se implementa utilizando un mecanismo de búsqueda y omisión que mejora significativamente el rendimiento del controlador MPPT y mejora la eficiencia de los sistemas fotovoltaicos. Los resultados se comparan con las técnicas recientemente desarrolladas de Artificial Bee Colony (ABC), Cuckoo Search Algorithm (CS), DragonFly Optimizer (DFO) y Particle Swarm Optimization (PSO). Los estudios de casos de condiciones de operación incluyen irradiancia de variación rápida y PS con GM sesgado. La técnica de control MPPT basada en DGBCO también está validada por la configuración experimental. Los resultados se comparan utilizando índices estadísticos y analíticos como el tiempo de seguimiento, el tiempo de asentamiento, la eficiencia de seguimiento de potencia, la energía total, RMSE, MAE y RE. Los resultados muestran el desempeño superior de la DGBCO propuesta. Relativamente, una recolección de energía entre un 2% y un 8% más alta y un tiempo de seguimiento hasta un 60% más rápido ayudan a lograr una eficiencia de seguimiento de potencia de hasta un 99,86% tanto en la operación de control transitorio como en la de estado estacionario. Los valores más bajos de las métricas estadísticas, es decir, RMSE, MAE y SR, indican la solidez y el modelado matemático efectivo de DGBCO para MPPT efectivo de sistemas fotovoltaicos en condiciones de PS. The application of small-scale electrical systems is widespread and the integration of Maximum Power Point Tracking (MPPT) control for Photovoltaic systems with battery applications further enhances the techno-economic feasibility of renewable systems. For this purpose, a novel MPPT control system using Dynamic Group based cooperation optimization (DGBCO) algorithm is utilized for PV systems. The population in the DGBCO is divided into exploration and exploitation groups. Due to effective mathematical modeling, the drawbacks of existing MPPT control techniques are undertaken. The drawbacks of modern MPPT control become prominent under partial shading conditions (PSC) which give rise to power loss, random fluctuations, and slow control action. The DGBCO is implemented using a search and skip mechanism which significantly enhances the performance of the MPPT controller and improves the efficiency of PV systems. The results are compared with recently developed Artificial Bee Colony (ABC), Cuckoo Search Algorithm (CS), DragonFly Optimizer (DFO), and Particle Swarm Optimization (PSO) techniques. The operating conditions case studies include fast varying irradiance and PS with skewed GM. The DGBCO based MPPT control technique is also validated by the experimental setup. The results are compared using statistical and analytical indices such as tracking time, settling time, power tracking efficiency, total energy, RMSE, MAE, and RE. The results show the superior performance of the proposed DGBCO. Relatively, 2%–8% higher energy harvest, and up to 60% faster tracking time helps to achieve up to 99.86% power tracking efficiency in both transient and steady-state control operation. Lower values of statistical metrices i.e. RMSE, MAE, and SR indicate the robustness and effective mathematic modeling of DGBCO for effective MPPT of PV systems under PS conditions. إن تطبيق الأنظمة الكهربائية صغيرة النطاق منتشر على نطاق واسع، كما أن دمج التحكم في الحد الأقصى لتتبع نقاط الطاقة (MPPT) للأنظمة الكهروضوئية مع تطبيقات البطارية يزيد من تعزيز الجدوى التقنية والاقتصادية للأنظمة المتجددة. لهذا الغرض، يتم استخدام نظام تحكم MPPT جديد باستخدام خوارزمية تحسين التعاون القائم على المجموعة الديناميكية (DGBCO) للأنظمة الكهروضوئية. ينقسم السكان في DGBCO إلى مجموعات استكشاف واستغلال. نظرًا للنمذجة الرياضية الفعالة، يتم إجراء عيوب تقنيات التحكم MPPT الحالية. تصبح عيوب التحكم الحديث في MPPT بارزة في ظل ظروف التظليل الجزئي (PSC) التي تؤدي إلى فقدان الطاقة، والتقلبات العشوائية، وإجراءات التحكم البطيئة. يتم تنفيذ DGBCO باستخدام آلية البحث والتخطي التي تعزز بشكل كبير أداء وحدة تحكم MPPT وتحسن كفاءة الأنظمة الكهروضوئية. تتم مقارنة النتائج مع تقنيات مستعمرة النحل الاصطناعي (ABC) المطورة حديثًا، وخوارزمية البحث عن الوقواق (CS)، ومحسن اليعسوب (DFO)، وتحسين سرب الجسيمات (PSO). تتضمن دراسات حالة ظروف التشغيل إشعاعًا سريع التباين و PS مع جنرال موتورز منحرف. كما يتم التحقق من صحة تقنية التحكم MPPT القائمة على DGBCO من خلال الإعداد التجريبي. تتم مقارنة النتائج باستخدام مؤشرات إحصائية وتحليلية مثل تتبع الوقت، ووقت الاستقرار، وكفاءة تتبع الطاقة، والطاقة الإجمالية، و RMSE، و MAE، و RE. تظهر النتائج الأداء المتفوق لـ DGBCO المقترح. نسبيًا، يساعد حصاد الطاقة الأعلى بنسبة 2٪-8 ٪، ووقت التتبع الأسرع بنسبة تصل إلى 60 ٪ على تحقيق كفاءة تتبع طاقة تصل إلى 99.86 ٪ في كل من عملية التحكم العابرة والمستقرة. تشير القيم المنخفضة للمقاييس الإحصائية مثل RMSE و MAE و SR إلى المتانة والنمذجة الرياضية الفعالة لـ DGBCO من أجل MPPT الفعال للأنظمة الكهروضوئية في ظل ظروف PS.