Lowest Total Loss Research Articles

Fabrication and Soft Magnetic Properties of Fe–Si–Cr Composites with Double-Insulating Layers Suitable for High-Frequency Power Applications

Soft magnetic composites (SMCs) are composed of alloy materials with the core and insulating layers as the shell. These composites exhibit high saturation magnetic sensitivity and low hysteresis loss, making them a promising material for various applications. The investigation of double layers is considered valuable as it can effectively address the issues of low resistivity and high dynamic loss that arise from non-uniform insulating layers in SMCs. In this study, Fe-Si-Cr/SiO2 particles with a core–shell heterostructure were produced via chemical vapor deposition (CVD). The Fe-Si-Cr/SiO2 materials were coated with different weight percentages (1–6%) of sodium silicate (SS). Subsequently, Fe-Si-Cr-based SMCs were synthesized through high-pressure molding and heat treatment. The effect of the SS weight percentage on microscopic changes and magnetic characteristics was investigated. These findings indicated that a concentration of 4 wt% of SS was the most effective at enhancing magnetic characteristics. The resultant SMCs exhibited high resistivity (21.07 mΩ·cm), the lowest total loss (P10 mt/300 kHz of 44.23 W/kg), a relatively high saturation magnetization (181.8 emu/g), and permeability (35.9). Furthermore, it was observed that the permeability exhibited stabilization at lower frequencies. According to these findings, the combination of CVD and double layers could lead to the further development of SMCs in a variety of applications.

Effect of Various Metal Oxide Insulating Layers on the Magnetic Properties of Fe-Si-Cr Systems

Iron-based soft magnetic composites (SMCs) are the key components of high-frequency electromagnetic systems. Selecting a suitable insulating oxide layer and ensuring the integrity and homogeneity of the heterogeneous core–shell structure of SMCs are essential for optimizing their magnetic properties. In this study, four types of SMCs—Fe-Si-Cr/ZrO2, Fe-Si-Cr/TiO2, Fe-Si-Cr/MgO, and Fe-Si-Cr/CaO—were prepared via ball milling, followed by hot-press sintering. The differences between the microscopic morphologies and magnetic fproperties of the Fe-Si-Cr/AOx SMCs prepared using four different metal oxides were investigated. ZrO2, TiO2, MgO, and CaO were successfully coated on the surface of the Fe-Si-Cr alloy powders through ball milling, forming a heterogeneous Fe-Si-Cr/AOx core–shell structure with the Fe-Si-Cr alloy powder as the core and the metal oxide as the shell. ZrO2 is relatively hard and less prone to breakage and refinement during ball milling, resulting in a lower degree of agglomeration on the surface of the composites and prevention of peeling and collapse during hot-press sintering. When ZrO2 was used as the insulation layer, the magnetic dilution effect was minimized, resulting in the highest resistivity (4.2 mΩ·cm), lowest total loss (580.8 kW/m3 for P10mt/100kHz), and lowest eddy current loss (470.0 kW/m3 for Pec 10mt/100kHz), while the permeability stabilized earlier at lower frequencies.

Earthquake Risk Study on Residential Buildings in West Jakarta using the Event-Based Risk Analysis Method

UNISDR (United Nations Office for Disaster Reduction) states that Indonesia is in the third-highest rank after Japan and the United States for the average economic loss due to earthquakes. Previous earthquake risk studies conducted by the National Agency for Disaster Management (BNPB) in 2011 renewed in 2016 both in the form of risk indexes have yet taken into account the vulnerability function of buildings, so that economic loss has not been presented quantitatively. This research aims to analyse earthquake risk in urban areas (West Jakarta Municipality) using the Event-Based Risk Analysis method by applying several factors including: earthquake source updates, GMPE, site-specific, exposure and building vulnerability functions. Hazard and risk analyses have been conducted for the probability of exceedance (PoEs) 10% and 2% in 50 years. Moreover, risk analysis was conducted for residential buildings exposure. The results predict that the lowest total building loss due to the earthquake per district is around 8.1 million USD and the highest loss is 15.5 million USD at a PoEs 10% in 50 years. Whereas for the PoEs 2% in 50 years, the lowest total loss was 14.86 million USD whilst the highest total loss was 25 million USD.

Минимизация технических потерь активной мощности в воздушных линиях электропередачи сверхвысокого напряжения с учетом коронирования проводов

A technique has been developed to minimize active power losses that takes into account the corona effect on extra-high voltage overhead power transmission lines in normal modes of their operation. The corona effect is modeled by a specific conductivity, which is a nonlinear function of the voltage level. The equivalent conductivity value is corrected for the actual weather conditions iteratively by changing the r.m.s. voltage value. A universal expression for estimating the effect of operating parameters on the change of voltage along the line length and a graphic illustration of this effect are presented. By differentiating the functional dependence of the total active power losses, formulas are obtained for calculating the operating parameters corresponding to the minimum loss values, assuming that the conductivity does not depend on voltage. It is shown that the operating and technical limitations on the voltage values at the line ends and in its intermediate sections significantly reduce the range of transmitted power with minimal losses. The iterative calculation sequence for determining the reduced voltage level corresponding to the lowest total losses is outlined. The transmitted power values at different corona intensities are calculated. The study results have shown the need to take into account the nonlinear dependence of equivalent conductivity on the r.m.s. voltage value.

The Influence of sowing time of red beet seeds on root crops storage

The aim of the study was to investigate the effect of seed sowing time on the red beet root crops conservation in the southwestern Forest-Steppe of Ukraine. It has been established that sowing periods affect the germination of red beet root. Thus, the lowest total losses were observed for sowing on May 1–4 in all the studied hybrids, namely in the Bettollo F1 hybrid – 6.7 %, the Voyevoda F1 – 9.9 %, and in the Ronda F1 hybrid – 14.9 %, respectively. The biggest losses were observed for sowing in the early spring term, since sowing beetroot in the early term results in the roots overripening, aging, cracking, they germinate during storage and become less resistant to rotting microorganisms. The highest output of commodity products was observed under sowing in late spring time. In this case, the yield of markered root beet root in the Bettollo F1 hybrid was 93.3 %, the Voyevoda F1 – 90.1 %, and in the Ronda F1 hybrid – 85.1 %, respectively. Bettolo F1 hybrid root crops were better preserved than others, which we believe is due to the mass of root crops, since the conservation of large and medium-sized root crops is higher than that of small ones. It should also be noted that the total root loss was lower under storage in boxes with a plastic insert, than that under the root loss stored in the boxes. Thus, the lowest total root loss was observed in the Bettollo F1 hybrid – 5.2–7.6 %, which is 0.1–2.0 % less than the Voyevoda F1 hybrid and 3.2–6.9 % less than in the Ronda F1 hybrid. In the Bettolo F1 hybrid, the disease losses were insignificant compared to the Voyevoda F1 and Ronda F1 hybrids and made 2.8–4.0 %. The natural weight loss in the hybrid Bettollo F1 was 2.4–3.6 %, which is almost on par with the hybrid Voyevoda F1 2.3–4.2 %, but much less than in the hybrid Ronda F1 3.8–6.6 %. Comparing the storage methods, it should be noted that storage root crops in boxes with a plastic insert contributes to a higher output of marketed products compared to variants where the root crops were stored in boxes in bulk. Thus, storage root crops in boxes with a plastic insert is the best way to store root beets as it allows to save the product with minimal loss. Key words: storage properties, hybrid, total losses, commodity products output, boxes, boxes with a plastic insert.

Lemongrass essential oil in sugarcane silage: Fermentative profile, losses, chemical composition, and aerobic stability

Essential oils have been used to manipulate microbial growth in different processes such as silage fermentation. This study aimed to evaluate the effects of increasing levels of lemongrass oil (LO) in sugarcane ensiling on fermentative profile and losses, chemical composition, in vitro degradation, and aerobic stability. Thirty-two experimental silos were used in a blocked randomized design to evaluate the following treatments: control (CON), sugarcane ensiling without LO; and increasing levels of LO on sugarcane ensiling: 1 (L1), 2 (L2), and 3 (L3) mL of LO per kg of sugarcane (as-fed basis). Results of LO level effects were regressed to access the maximum/minimum points. Lemongrass oil linearly increased NH3-N and decreased the count of mold and yeast, lactic, and butyric acid concentrations. Besides, LO quadratically affected silage pH, Brix, and levels of ethanol and acetic acid. The lowest silage pH, ethanol, and acetic acid concentration were found with 1.17, 2.22, and 1.89 mL/kg of LO. Lemongrass oil quadratically affected fermentative losses, dry matter (DM) recovery, and chemical composition of silage. The lowest total losses were found at 1.53 mL/kg of LO, whereas the highest DM recovery was obtained using 1.90 mL/kg LO. Intermediary levels of LO (1.99–2.00 mL/kg) improved silage DM, organic matter, non-fiber carbohydrate, and ether extract content, whereas reduced silage concentration of neutral detergent fiber, acid detergent fiber, lignin, and crude protein. Lemongrass oil did not affect neutral detergent fiber in vitro degradation and quadratically affected DM degradation of silage, whereas linearly increased silage aerobic stability (h) and temperature of silage between 48 and 104 h after aerobic exposure. Thus, intermediary levels (between 1.53 and 2.22 mL/kg) of LO reduces ethanol concentration and fermentative losses of silages, improving DM recovery, chemical composition and DM degradation of sugarcane silage. Additionally, LO levels linearly decrease yeast and mold count and increase the aerobic stability of sugarcane silage.

An All-SiC Three-Phase Buck Rectifier for High-Efficiency Data Center Power Supplies

The low power losses of silicon carbide (SiC) devices provide new opportunities to implement an ultra high-efficiency front-end rectifier for data center power supplies based on a 400- <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX"> ${\rm V}_{\rm dc}$</tex></formula> power distribution architecture, which requires high conversion efficiency in each power conversion stage. This paper presents a 7.5-kW high-efficiency three-phase buck rectifier with 480- <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{V}_{{\rm ac}, {\rm rms}}$</tex></formula> input line-to-line voltage and 400- <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm V}_{\rm dc}$</tex></formula> output voltage using SiC MOSFETs and Schottky diodes. To estimate power devices' losses, which are the dominant portion of total loss, the method of device evaluation and loss calculation is proposed based on a current source topology. This method simulates the current commutation process and estimates devices' losses during switching transients considering devices with and without switching actions in buck rectifier operation. Moreover, the power losses of buck rectifiers based on different combinations of 1200-V power devices are compared. The investigation and comparison demonstrate the benefits of each combination, and the lowest total loss in the all-SiC rectifier is clearly shown. A 7.5-kW prototype of the all-SiC three-phase buck rectifier using liquid cooling is fabricated and tested, with filter design and switching frequency chosen based on loss minimization. A full-load efficiency value greater than 98.5% is achieved.

A Study on the Effect of Low-loss Additives on the Property of NiCuZn Ferrite

The electromagnetic properties and microstructures of the ferrites based on ( )() were investigated by changing the amount of additive SnOand CaO and the sintering temperatures. Addition of caused pores in the specimen. There was no variation of grain size by changing the amount of additives. Total loss was reduced when ( ) () composition was sintered at rather than . Addition of CaO was useful to reduce the total loss because it increased the sintering density. The lowest total loss was obtained when 0.06 wt% and 0.4 wt% CaO were added at the same time.

Intermittent Warming Reduces Chilling Injury and Decay of Tomato Fruit

ABSTRACTMature‐green and early breaker tomato fruit (Lycopersicon esculentum Mill) cv‘Dario F‐150’treated with 0.5g liter‐1 iprodione were stored at 6, 9 and 12°C for 28 days. Intermittent warmings for 1 day at 20°C were applied every week on all fruits. They were subjected to post‐storage ripening for 4 days at 20°C. On tomatoes from both maturity stages, intermittent warming during four cycles of 6 days at 9°C and 1 day at 20°C prevented development of chilling injury and decay, enhanced surface color and loss of firmness (compared with continuous 9°C storage), (delayed shriveling, and resulted in the lowest total losses at the end of storage and at the end of post‐storage ripening.