MODERN APPROACHES TO DIAGNOSTICS AND REPAIR OF LOW-POWER SWITCHING POWER SUPPLIES

Рассмотрены вопросы оптимизации технологических процессов поиска и устранения неисправностей маломощных DC-DC преобразователей, изготавливаемых ООО «АЕДОН». Перечислены наиболее характерные неисправности, встречающиеся у импульсных источников питания малой мощности. Рассмотрены основные методы поиска и устранения неисправностей, применяемые в процессе диагностики импульсных преобразователей. Предложен подход, основывающийся на комбинировании различных методов диагностики и ремонта, позволяющий увеличить эффективность поиска и устранения неисправностей импульсных DC-DC преобразователей. Рассматриваемый подход позволил повысить оперативность технической диагностики и ремонта в условиях серийного производства, а также был эффективно использован при первоначальной подготовке молодых специалистов участка регулировки и тестирования. В качестве примера представлена процедура поиска и устранения причин повышенного напряжения холостого хода в маломощных импульсных источниках питания. Рассмотрены причины появления дефекта как в одиночных модулях, так и во всей партии. Проведено экспериментальное исследование влияния обратной связи на выходное напряжение модуля в режиме холостого хода, показано влияние возможных неисправностей. В результате применения данной процедуры в короткий срок была произведена диагностика и ремонт маломощного импульсного источника питания (ИИП), выполнена регулировка обратной связи по напряжению The article considers the issues of optimization of technological processes for troubleshooting low-power DC-DC converters manufactured by company AEDON. We listed the most typical malfunctions that occur in low-power switching power sources. We considered the main methods of troubleshooting used in the process of diagnostics of pulse converters. We propose an approach based on the combination of various diagnostic and repair methods, which allows one to increase the efficiency of troubleshooting of pulsed DC-DC converters. The considered approach allowed us to increase the efficiency of technical diagnostics and repair in the conditions of mass production, and was also effectively used in training of young specialists of the adjustment and testing subdivision. As an example, we present the procedure for finding and eliminating the causes of increased idle voltage in low-power switching power sources. We considered the reasons for the appearance of the defect both in single modules and in the entire batch. We carried out an experimental study of the effect of feedback on the output voltage of the module in the idle mode. We showed the influence of possible failures. As a result of the application of this procedure, we performed diagnostics and repair of a low-power switching power supplies in a short time and adjusted the voltage feedback

Current Harmonic Aggregation Cases for Contemporary Loads

Power electronic circuits in modern power supplies have improved the conversion efficiency on the one hand but have also increased harmonic emissions. Harmonic currents from the operation of these units affect the voltage waveforms of the network and could compromise the reliability of the network. Load and source non-linearity can, therefore, limit the renewable source’s hosting capacity in the grid, as a large number of inverter units may increase the harmonic distortions. As a result, voltage and current distortions could reach unbearable levels in devices connected to the network. Harmonic estimation modelling often relies on measurement data, and differences may appear in mathematical simulations as the harmonic aggregation or cancellation may generate different results due to the inaccuracies and limitations of the measurement device. In this paper, the effect of harmonic currents cancellation on the aggregation of different load currents is evaluated to show its impact in the network by presenting a comparison between the measurement and mathematical aggregation of harmonics. Furthermore, the harmonic cancellation phenomenon is also qualified for multiple loads connected to the power supply.

SINGLE HOP AUTHENTIC BROADCASTING IN SOCIAL MOBILE NETWORKS USING BLUETOOTH

This paper aims to create infrastructure-free networking capabilities for people in need such as when inadequate infrastructure including mobile cell towers and power supplies are damaged or when all communication means are restricted. In general, this means finding a way to communicate without mobile cell towers, repeaters, or Wi-Fi hotspots on mobile devices. This paper focuses on introducing an ad-hoc network based on Bluetooth where users can communicate without barriers. The proposed network implementation uses Google’s API Nearby Connection which is one of Google Play Services that can provide high bandwidth, low latency, encrypted data transfers between nearby devices in a fully-offline P2P mode. Kotlin language was used to program an application called BlueEmergency installed on Android devices to broadcast data as bytes payloads in a form of text messages from one node to all nodes in proximity using Bluetooth only. The test and verification of the system are performed showed that successful communication is achieved with the latest versions of both the Android operating system and Bluetooth. Finally, the designed network can be extended to cover large geographical areas by multi-hopping the messages between devices to make the system more efficient to use in the time of need.

Degradation processes in tungsten filaments at high temperatures

Degradation processes in tungsten filaments of lighting lamps under normal operating conditions are experimentally studied. The duration of each measurement in continuous mode is about 18 hours. To increase the measurement accuracy, subtraction (compensation) of the constant component of the voltage is used. To compensate for the constant component of the voltage, a low noise reference DC voltage source is used. Using this scheme allowed decreasing the influence of the inherent noise of power supplies without suppressing degradation processes. It is shown that the relative change in resistance during the measurement does not exceed 2.8·10−3. It is also shown that the joint influence of voltage fluctuations of power supplies and low noise reference voltage source on the measurement results corresponds to a relative change in a resistance equal to 2.8·10−4. The study of degradation processes can be used to assess the reliability (and durability) of products in electrical engineering and radio electronics.

Cross-sectional assessment of government health center needs to implement long-acting reversible contraception services in rural Rwanda

Background There is unmet need for family planning in Rwanda. We previously developed an evidence-based couples’ family planning counseling (C)FPC program in the capital city that combines: (1) fertility goal-based family planning counseling with a focus on long-acting reversible contraceptive (LARC) for couples wishing to delay pregnancy; (2) health center capacity building for provision of LARC methods, and (3) LARC promotion by community health workers (CHW) trained in community-based provision of oral and injectable contraception. From 2015 to 2016, this service was integrated into eight government health centers in Kigali, reaching 6072 clients and resulting in 5743 LARC insertions. Methods From May to July 2016, we conducted cross-sectional health center needs assessments in 30 rural health centers using surveys, key informant interviews, logbook extraction, and structured observations. The assessment focused on the infrastructure, materials, and human resources needed for LARC demand creation and provision. Results Few nurses had received training in LARC insertion [41% implant, 27% intrauterine device (IUD)]. All health centers reported working with CHW, but none trained in LARC promotion. Health centers had limited numbers of IUDs (median 10), implants (median 39), functional gynecological exam tables (median 2), and lamps for viewing the cervix (median 0). Many did not have backup power supplies (40%). Most health centers reported no funding partners for family planning assistance (60%). Per national guidelines, couples’ voluntary HIV counseling and testing (CVCT) was provided at the first antenatal visit at all clinics, reaching over 80% of pregnant women and their partners. However, only 10% of health centers had integrated family planning and HIV services. Conclusions To successfully implement (C)FPC and LARC services in rural health centers across Rwanda, material and human resource capacity for LARC provision will need to be greatly strengthened through equipment (gynecological exam tables, sterilization capacity, lamps, and backup power supplies), provider trainings and follow-up supervision, and new funding partnerships. Simultaneously, awareness of LARC methods will need to be increased among couples through education and promotion to ensure that demand and supply scale up together. The potential for integrating (C)FPC with ongoing CVCT in antenatal clinics is unique in Africa and should be pursued.

Electric Power Material Logistics Distribution Based on Improved Multi-Population Particle Swarms

In view of the problem that the information requirements of electric power supplies logistics distribution are increasingly high, this study proposes the research of electric power supplies logistics distribution based on improved multi-population particle swarm. Firstly, the simulated annealing algorithm is introduced in detail, and then the particle swarm optimization (PSO) is improved by using the domain extension method. Then the multi-population particle swarm optimization was carried out through the optimization of coding system, the updating speed formula and the algorithm convergence control. Finally, the optimization effect was verified. Final results show that, this study put forward based on improved particle swarm more population of electricity supplies logistics distribution model has feasibility and suitability, through the optimized parameters and algorithm of the model, to identify the logistics network of electric power supply company the best optimization model, thus reducing power cost of inventory and logistics distribution time, so as to improve the efficiency of logistics distribution.