The influence of use systems on the productivity of shrubephemeral desert pastures and the preservation of herbage

The article is devoted to the urgent problem of developing a scientifically based organization and use of distant pastures in the south of Kazakhstan. It has been found that the composition and diversity of pasture grasses have significant effect on the forage value of the grass stand and ultimately affect the forage capacity of desert pastures. Grazing of farm animals should be carried out with an optimal load on pastures, that is, no more than 70% of the productivity of the pasture mass should be exploited. Due to the better preservation of various types of forage plants and pasture herbage in general with systematic use, the yield of pastures in the summer season was 6.15 c/ha, in other words it was higher by almost 1.0 c/ha of dry forage mass compared to unsystematic grazing (5.20 c/ha). All pasture plants exploited in early spring produced aftermath in 10–15 days and were well preserved from overexploitation and trampling.

Load & Resistance Factors Calibration for Front Covered Caisson Breakwater

Calibration of load-resistance factors for the limit state design of front covered caisson breakwaters were presented. Reliability analysis of the breakwaters which are constructed in Korean coast was conducted. Then, partial safety factors and load-resistance factors were sequentially calculated according to target reliability index. Load resistance factors were optimized to give one set of factor for limit state design of breakwater. The breakwaters were redesigned by using the optimal load resistance factor and verified whether reliability indices larger than the target value. Finally, load-resistance factors were compared with foreign country’s code for verification.

ECONOMIC DAMAGE ASSESSMENT METHODOLOGY IN CASE OF TRANSFORMER LOAD RATIO DEVIATION

The aim of the study is to develop a methodology for assessing economic damage when the transformer load factor deviates. In the process of research, a method was used to determine the optimal load of a power transformer. A method for assessing economic damage in case of a deviation of its load factor has been developed. The optimal load factor of a power transformer has been determined according to the criterion of the minimum cost of money for the transformation of electrical energy. The load level of power transformers can be assessed by two criteria: by the maximum integral value of the effi ciency and by the minimum loss of money during the transformation of electricity. According to the proposed methodology, the assessment of damage is carried out when the load factor of the transformer deviates from the optimal values, for which the relative losses of electrical energy are calculated. The results obtained when evaluating energy and fi nancial and economic effi ciency show that when the load factor is overestimated relative to the optimal values, it is much more preferable to overestimate than underestimate. The reliability of the results is confi rmed by the satisfactory agreement of the calculated results with the experimental data obtained at the operating power plant.

Collaborative Optimization Method of Power and Efficiency for LCC-S Wireless Power Transmission System

Dynamic wireless charging enables moving equipment such as electric vehicles, robots to be charged in motion, and thus is a research hotspot. The applications in practice, however, suffer from mutual inductance fluctuation due to unavoidable environmental disturbances. In addition, the load also changes during operation, which makes the problem more complicated. This paper analyzes the impacts of equivalent load and mutual inductances variation over the system by LCC-S topology modeling utilizing two-port theory. The optimal load expression is derived. Moreover, a double-sided control strategy enabling optimal efficiency and power adjustment is proposed. Voltage conducting angles on the inverter and rectifier are introduced. The simulation and experimental results verify the proposed method.

A Multi-Mode Broadband Vibration Energy Harvester Based on MEMS 3D Coils

This paper presents an electromagnetic vibration energy harvester utilizing 3D MEMS coils and multi-mode structure to improve the output power and broaden the frequency band. We fabricated and assembled the prototype, with a pair of 3D coils fabricated by lithography, silicon etching, silicon direct bonding and copper electroplating, et al., which are compatible with CMOS processes. The numerical simulation was conducted to analysis the vibration modes of the spring-mass system, which revealed the multi-mode mechanism of serpentine springs. We also tested the output power-frequency curves for different load and excitation acceleration to investigate the optimal load resistance and the influence of excitation. The test results showed that the proposed prototype can generate 1.2μW power under 992Hz for 1g acceleration with a half-power bandwidth of 65Hz, which are higher than some recent published data, proving the superiority of proposed structure.