Leakage Current Mitigation of Photovoltaic System Using Optimized Predictive Control for Improved Efficiency

This paper proposes an optimized predictive control strategy to mitigate the potential leakage current of grid-tied photovoltaic (PV) systems to improve the lifespans of PV modules. In this work, the PV system is controlled with an optimized predictive control algorithm that selects the switching voltage vectors intelligently to reduce the number of computational burdens. Thus, it improves the dynamic performance of the overall system. This is achieved through a specific cost function that minimizes the change in common-mode voltage generated by the parasitic capacitance of PV modules. The proposed controller does not require any additional modulation schemes. Normalization techniques and weighting factors are incorporated to obtain improved results. The steady state and dynamic performance of the proposed control scheme is validated in this work through simulations and a 600 W experimental laboratory prototype.

Characteristics of reduced fat mayonnaise using pumpkin flour (Cucurbita moschata) as fat replacer

Reduced fat mayonnaise has the disadvantage of destabilization of emulsion. Emulsion destabilization that occurs is the separation of oil and water. Pumpkin flour is used to increase the viscosity and stability of the emulsion. The objective of this study was to determine the best percentage of the use of pumpkin flour in reduced fat mayonnaise based on pH, emulsion stability, moisture content, and sensory evaluation. The material used in this research was mayonnaise made from egg yolk, canola flower oil, vinegar, pumpkin flour as a fat replacer carbohidrates based, and other optional ingredients. The method used was an experimental laboratory with a completely randomized design with 4 treatments and 4 replications. The treatments consisted of without the use of pumpkin as a control, the use of pumpkin flour 2%, 4%, and 6% of the total oil used. The variables measured were pH, emulsion stability, moisture content, and sensory evaluation. The results showed that the use of pumpkin flour on mayonnaise gave highly significant effect on pH, stability emulsion, moisture content and increased panelists preferences. The conclusion of the study that using 6% pumpkin flour produced the best reduced-fat mayonnaise.

Chemical and sensory properties of analogue rice based on kimpul flour (Xanthosoma sagitifolium)

Analog rice is artificial rice shaped like rice grains made from non-rice carbohydrate-rich flour with water, which can overcome food security in Indonesia. Taro kimpul is a local food rich in carbohydrates that cannot be widely used. Therefore, kimpul thread has the potential to be used as raw material in the manufacture of analog rice. This study aimed to determine the chemical characteristics of kimpul taro analog rice with dyes and binders. In addition, it is expected to increase consumer acceptance based on sensory testing. This research method uses an experimental laboratory method by making analog rice with 4 formulations. The analysis was water content, ash content, protein content, fat content, carbohydrate content, and sensory (hedonic) analysis, including colour, taste, texture, and overall aroma. The results showed that analog rice A was the best formula selected using the Bayes method based on the results of chemical and hedonic tests. Chemical and sensory characteristics of analog rice A with the use of 4% CMC and 32% beet are as follows moisture 2.88%; ash 2.3%; fat 1.1%; 5.7% protein; carbohydrate 87.94% and a preference value with an average range of neutral-good.

Production of electrolytic copper from Zhezkazgan Processing Plant tailings leaching solutions using a hydro-impulse discharge

In this work, for the first time, studies of the mineralogical composition and chemical semi-quantitative spectral analysis (SQSA) of the Zhezkazgan processing plant tailings before and after leaching were carried out. It was found that copper is present in the tailings in the form of the chalcosine and bornite minerals. After leaching with the use of ammonium bifluoride and a hydro-pulse discharge, chalcosine and boronite are destroyed, and copper passes into a solution containing phosphoric acid. As a result of multiple placing of tailings into the solution, the copper content in it is brought to a concentration at which copper deposition on a stainless steel plate is possible. The identification of copper was implemented on a LAES-Matrix grain spectrometer. A visual comparative analysis of the changes in the structure of the treated ore waste was carried out using a TESCAN MIRA scanning electron microscope. Metallic copper was obtained from solution by electrochemical reactions in an experimental laboratory setup as a result. The technology was developed on an experimental laboratory setup for the extraction of metallic copper and brought the choice of the solution medium and electrochemical processes to the stage of obtaining the target metal with a purity of 99.99 %

Representation of Game Phrase-Making Mechanisms in Educational Dictionary: Practical Lexicography

The practical experience of the vocabulary representation of the mechanisms of game phraseology is described, the difficulties of lexicography of phraseological units built on the game paradox are listed, the ways to solve the problem of etymologization of phraseological games in the educational dictionary are showed. The main positions of the innovative technology for constructing educational phraseological dictionaries in paper format are presented. The relevance of the research is due to the great developmental impact of phraseological games on the addressee-child and the need to improve the system of their lexicographic description for educational purposes. The novelty of the research lies in the appeal to the unexplored problematic of describing phraseological games and the development of a technique for etymological paraphrasing, including interpretive and plot-compositional techniques, which are implemented in a twolevel configurative structure of etymological paraphrase. Special attention is paid to lexicographic techniques that allow revealing the specifics of phraseological games built on false imagery, as well as phraseological games, the content plan of which is not opposed to the expression plan, and their actual meaning is logically justified and motivated. Examples of dictionary entries of new phraseographic projects of the Experimental Laboratory of Educational Lexicography of Pskov University are given — a quest dictionary and a phraseological puzzle dictionary, the genres of which adequately reveal the specifics of phraseological games.

The Effect Of Heating Acrylic Resin Of Various Types With Different Temperatures On Impact Strength

Resin polymerization which is affected by unstable temperature causes the resin to break easily. The strength of the base material is affected by the forces acting in the mouth, such as transverse forces, other resistance or fatigue, and flexibility. Fracture of denture caused by masticatory loads and is affected by forces acting in the mouth, including transverse, resistance or fatigue, and flexural forces. Experimental Laboratory total of 72 samples consisting of 18 samples of type A, B and C cured at normal temperature, 100oC, 200oC, and 300oC. Types A, B and C have the effect of heating with the addition of temperature on the impact strength of acrylic resin, because the value of sig = 0.001 < 0.05, so H0 is rejected. An effect with the addition of temperature on the impact strength of the resin types A, B and C, because sig = 0.001 < 0.05, so H0 is rejected, which means that the average results are significantly different due to differences in temperature.

The effect of toxic metal As on the Matricaria Chamomilla L. medicinal plant

The paper presents an experimental laboratory study of the bioaccumulation of the toxic metal arsenic in the medicinal plant chamomile (Matricaria Chamomilla L.). The study makes a comparison regarding the bioaccumulation capacity of the chamomile plant in which arsenic is found as a unique contaminant, as well as in mixtures of 2, 3, or 4 toxic metals (Cd, Ni and Pb) on a natural soil enriched with metals, compared to the chamomile plant developed on an unpolluted substrate. The tests followed the effects of soil pollution with metals on the germination and development of chamomile. The experimental results indicated that arsenic does not bioaccumulate in the chamomile plant, remaining in the soil. The experiment that was an exception is the one with arsenic as the only contaminant (E1) in which at 90 days, the arsenic content in the chamomile plant was 3.58 mg/kg arsenic, the value that is within normal limits, below the phytotoxic value of 5 mg/kg, but was higher than that determined in the plant from the control test experiment (<0.75 mg/kg). The bioaccumulation factor (BCF) after 90 days, in all experiments, either by a combination of metals or a single contaminant had values lower than 1, indicating that the plant does not accumulate arsenic. The total chlorophyll from the results obtained indicates that the toxicity in the E1 experiment is higher than in the metal mixture.

Разработка инновационной энергосберегающей технологии очистки резервуаров путем диспергирования отложений

An obvious global trend in recent years is the increase in the proportion of viscous and heavy oils featured by high density and content of asphalt-resin-paraffin deposits. Due to the deterioration of the rheological properties of oil, the processes of its extraction, preparation in the fields, further transportation and subsequent processing have been made more difficult. The object of the study is the cleaning of oil and petroleum products storage tanks from the accumulated bottom sediments. The existing methods of tanks cleaning have been analyzed, the most promising methods and technical means for removing sediment and reducing the volume of sediment formation have been identified. The urgency of the development and implementation of innovative technologies enabling minimization of accumulation of deposit to reduce the scope of work in tank cleaning has been established. In this regard, experimental laboratory studies were conducted to determine the effectiveness of ultrasonic exposure with the occurrence of cavitation on the rheological properties of oil. The obtained results are indicative of a positive effect of ultrasound treatment of high-paraffin oil, such effect been expressed in decreased oil viscosity. A method is proposed for cleaning the tank from bottom sediments with the use of hydraulic washout system and ultrasonic plant. That method is based on the use of the cavitation effect caused by high-frequency waves, which makes it possible to temporarily adjust the rheological properties of oil and sludge deposit, reduce the deposit deposition rate and thereby slow down the process of sediment deposition during the storage of oil and petroleum products in large-volume tanks. Очевидной тенденцией последних лет в мире является увеличение доли вязких и тяжелых нефтей, характеризующихся высокой плотностью и содержанием асфальтосмолопарафиновых отложений. Вследствие ухудшения реологических свойств нефти затрудняются процессы ее добычи, подготовки на промыслах, дальнейшей транспортировки и последующей переработки. Объектом исследования является очистка резервуаров для хранения нефти и нефтепродуктов от образующихся донных отложений. Проанализированы существующие способы очистки резервуаров, выявлены наиболее перспективные методы и технические средства для удаления осадка и снижения объема образования отложений. Установлена актуальность вопроса разработки и использования инновационных технологий, позволяющих минимизировать выпадение осадка с целью уменьшения объема работ при очистке резервуаров. В этой связи проведены экспериментальные лабораторные исследования для определения эффективности ультразвукового воздействия с возникновением кавитации на реологические свойства нефти. Полученные результаты свидетельствуют о положительном эффекте обработки ультразвуком высокопарафинистой нефти, который выражается в снижении ее вязкости. Предложен способ очистки резервуара от донных отложений с применением гидравлической системы размыва и ультразвуковой установки. Он основан на использовании эффекта кавитации, вызываемой посредством высокочастотных волн, что позволяет провести временную корректировку реологических свойств нефти и осадка нефтешлама, снизить скорость выпадения осадка и таким образом замедлить процесс образования отложений при хранении нефти и нефтепродуктов в резервуарах большого объема.

A Laboratory Investigation of the Probable Mechanisms of the Action of an Artificial Thunderstorm Cell on Model Aircraft Radomes

The results of experimental laboratory investigations of possible mechanisms of the impact of lightning and thunderclouds on aircraft radomes and equipment inside them are presented. An artificial thunderstorm cell of negative polarity and model aircraft radomes with lightning diverter strips have been used. Experiments have shown that the discharge processes in a radome model significantly depend on the magnitude of the charge that accumulates on the inner and outer surfaces of the radome shell. It is established that the accumulation of large-magnitude charges of different signs on the outer and/or inner surface of the radome (up to hundreds of µC/m2) shell leads to a multivariance of the mechanisms of development of discharge processes inside the radome model, along its surface, and in the space near it. Significant influence of the “reverse” discharge from the antenna model under the radome on the types of current impulses recorded on the antennas under impact of the artificial thunderstorm cell is established. Peculiarities of the discharge formation in the radome model when using solid and segmented diverter strips for its protection are revealed. Parameters of the current impulses registered on the diverter strips and the antennas have been determined. Based on the conducted research, the possible mechanisms of the impact of thunderclouds and lightning discharges on radio-transparent aircraft radomes and the equipment inside them are considered.