Micro Hydro Power Plant for Sustainable Energy in Rural Electrification: A Case Study in Cameroon

The state of Cameroon, faced with the situation the electricity deficits, is promoting the development of renewable energies in general and to meet rural electrification needs in particular. The purpose of this work is to study the feasibility of the MHP of Batcheu, to show its contribution to sustainable development in this locality and to prove that it is a profitable project. After study, it appears that the waterfall of Batcheu is favourable to the establishment of a MHP with an installed power of 260 kW with an operating diagram corresponding to a Francis turbine. Given that it is a renewable energy that can supply more than 800 households in rural areas, its contribution to sustainable development is obvious. Its investment cost is estimated at 171,465,396 FCFA. It is a profitable project with a payback time of 7 years and 2 months.

QDOT MICRO^(TM)导管两种模式与传统导管功率控制模式对消融损伤灶影响的对比研究

目的探讨QDOT MICRO^(TM)(QDOT)导管两种模式消融效果的安全性,以及与传统导管功率控制(PC)模式相比不同参数设置对消融创痕的影响。方法应用新鲜离体猪心,比较QDOT导管的温度/流速控制(TFC)模式与THERMOCOOL SMARTTOUCHTM SF(STSF)导管的PC模式在不同消融指数(AI,400、500)分组下的创痕大小和安全性。同时评估QDOT导管的超高功率短时程消融模式(vHPSD)和TFC模式在不同接触压力(5、15和30 g)和不同贴靠角度(0°、45°和90°)分组下的创痕大小和安全性,并对比两种模式在不同消融间距(4 mm和6 mm)分组下创痕的均匀性、连续性和安全性。结果在AI相同时,TFC与PC模式所产生的创痕的深度、表面宽度、最大横径以及体积的差异均无统计学意义(均为P>0.05)。与目标AI为400时TFC模式相比,vHPSD模式所产生创痕的表面宽度和最大横径的差异均无统计学意义(均为P>0.05),但vHPSD模式产生的创痕更浅[(1.95±0.38)mm比(2.72±0.31)mm,P<0.001]、体积更小[(30.35±11.34)mm^(3)比(48.78±19.82)mm^(3),P=0.040]。接触压力对创痕情况影响不显著,各参数差异均无统计学意义(均为P>0.05)。各组创痕表面宽度均在贴靠角度90°时最小,且在目标AI为500的TFC模式组不同贴靠角度导致的创痕表面宽度差异有统计学意义(P=0.027)。此外,消融间距为4 mm时,vHPSD模式和TFC模式均能产生均匀且连续的线状创痕;消融间距为6 mm时,vHPSD模式和目标AI为400的TFC模式组所产生的创痕均不连续,而目标AI为500的TFC模式组产生的创痕具有良好的连续性。应用QDOT导管和STSF导管消融均未产生气爆和焦痂。结论在AI相同时,QDOT导管的TFC模式与STSF导管的PC模式消融效果相似。与TFC模式相比,vHPSD模式产生的创痕深度更浅,体积更小。QDOT导管的TFC模式和vHPSD模式安全性均较高。

A Miniaturized Broadband Wilkinson Power Divider Using Micro-Strip Branch Lines

A miniaturized broadband Wilkinson power divider is proposed. Micro-strip branch lines are introduced to replace multiple resistors used in multi-stage Wilkinson power dividers to increase the bandwidth of single-stage Wilkinson power dividers. To demonstrate its performance, an improved single-stage Wilkinson power divider with four micro-strip branch lines was designed. Simulated results show that the insert loss is better than 3.2 dB, the input return loss, output return loss, and isolation are better than 15 dB respectively, across a 76% bandwidth from 18 to 40 GHz. .

Rockwell Micro800PLC与Power flex变频器控制电机

Rockwell Micro800系列PLC通过Ethernet/IP端口接入Ethernet中,与其他的通讯设备相连接,因此可以将PLC与Power Flex变频器进行连接,然后通过在变频器的组态界面中添加外接设备后,进行实际设备的连接,如此将PLC与变频器和电机连接在一起。通过在Micro800控制器的编程软件中编写程序,通过上传设备信息和下载程序到PLC中来实现对电机的正反转和启动停止等控制,还可以修改变频器的参数来达到改变电机状态的目的。

Micro-arc Oxidation Inverter Power Supply Based on the Limited Bipolar Soft-switch Control Method

In order to overcome many limitations of the conventional power supplies, such as ponderosity, big wastage, and simplex output characteristic, a dual-inverter power supply is designed to meet the different requirements of micro-arc oxidation. The main circuit structure and principle of the dual-inverter power supply for micro-arc oxidation is described, the control system and the control adjustment method are also introduced. The dual-inverter technology is adopted in micro-arc oxidation power supply. The limited bipolar control mode is applied in the power inverter circuit for adjusting the voltage, and various voltage waveform can be obtained by controlling the chopper circuit. Meanwhile, the control accuracy and response speed are improved greatly because of the higher inverter frequency. The power supply can output direct current（DC） waveform, DC pulse waveform, symmetry alternating current（AC） waveform, asymmetry AC waveform, and so on. Besides, the parameters such as pulse width, range, frequency, duty cycle can be adjusted. The experimental result shows that the power supply has many advantages, such as stable output, wonderful waveform consistency and obvious advantage in technique, and it can meet the requirements of micro-arc oxidation process fully.

EXPERIMENTAL STUDY ON MACRO AND MICRO-STRUCTURE OF METALLIC PARTS BUILT BY LOW-POWER LASER CLADDING

A low-power CO_2 laser is used to deposit Fe powder and mixture of Fe andcarbon powder on substrates respectively, and the macro and micro-structure of the formed samplesare investigated. It is demonstrated that most grains of these samples are equi-axed. This isderived from the high nucleation velocity in the shallow melt pool besides rapid solidification ofthe liquid-state alloy or metal. Bainitic structure, combination of pearlite and ferrite structureand ferrite structure are seen respectively in the samples involving various amounts of carbon owingto no martensitic transformation in these small samples.

RESEARCH AND APPLICATION OF LF WAKE-UP TECHNOLOGY TO MICRO-POWER ACTIVE RFID

Tags of micro-power active RFID system are usually supllied by cells battery, the power consumption is a crucial factor. The currently applied operating mode is of timing wake-up. In this paper, presented the method of LF wake-up technology , discussed how to use it to solve the low-power problem of active RFID tag. Put forward the crucial electrocircuit and working program flow. Practices show that this solution is capable of solving the problem of low-power of active RFID.

Sustainable Development around Small Scale Mining Areas by the Development of Micro Hydro Power: Application Cases in Cameroon

Of all the precious metals buried in the Cameroonian subsoil, gold is certainly the longest exploited. It has longtime been the subject of artisanal exploitation. In 2014, the monthly national production was estimated at around 170 kg. In these mining areas, people still live in a screaming precariousness of which one of the main causes is often the lack of electricity, because of the distance of these localities to the national electricity network. Cameroon has a great hydroelectric potential, but the access rate to electricity is still very low in isolate or rural areas of this country. The objective of this work is to show that it is possible to efficiently exploit gold in isolated areas and contribute to the sustainable development of these localities through the development of micro hydro power (MHP). The mining community of Tikondi in the East Region of Cameroon is the practical case study for an illustration. The results of this study show that the development of the MHP project can be developed with installed power of 87 kW, where the Banki-Michell turbine is recommended according to the Sulzer-Escher Wyss diagram. The investment cost evaluated at 79,832,775 FCFA (1 Euro = 656 FCFA). It is a profitable project with a maximum payback period of 8 years. This project can be easily funded by gold mining activity. That Tikondi’s MHP can make this village becoming attractive for others activities, improving the quality of education of children (there is not any school and lots of them do not go to school), the building of health centers and the quality of life in that locality and therefore contribute to their sustainable development too.

Development of a Renewable Energy Based DC Excitation System in a Micro Hydro Power Plant

MHPPs （micro hydro power plants） have become prominent in hydropower plants as a solution to provide the energy demands of the grid. In this study, a new hybrid renewable energy based DC excitation system for synchronous generator in the developed MHPP system is introduced. Proposed hybrid DC excitation system consists of solar ＆ hydrogen energy based power generating systems. Hybrid renewable energy based system is used for the excitation of the synchronous generator in the MHPP test system. The renewables are used as a secondary energy source to provide the excitation current to a synchronous generator that generates energy in MHPP. A PV （photovoltaic） array is used as the main source of excitation, and a FC （fuel cell） stack is used for DC excitation in the lack of sunshine. In the experimental setup, an electrical control card is developed, and a microcontroller is used to perform the proposed excitation system. All experimental results obtained from 5 kW rated power MHHP test system. Experimental results show that, the proposed method provides the continuous excitation current, and the operation of the synchronous generator is uninterrupted. The proposed method is also practical and easily implemented for MHPP systems.

Temperature measurement based on radialization power for micro-hotplate

A novel method to measure the temperature on the surface of micro-hotplate was presented. The tiny fiber probe and the optical power meter were employed to measure the sample radialization power. By means of comparing the relationship between the radialization power and the temperature, sample surface temperature can be discerned accurately. Such an approach has provided more accuracy than traditional temperature measurements. The experimental result based on this method is quite similar to that of simulation by the finite element analysis (FEA) software of Ansys in theory. This measurement is very useful for measuring temperature for these micro samples prone to be untouchable.

An Air-Breathing Micro Direct Methanol Fuel Cell with 3D KOH-Etched Cathode Structure

A micro direct methanol fuel cell （μDMFC） using MEMS technology is reported. The prototype features a unique 3D air-breathing cathode structure fabricated using KOH etching and double-side lithography. The optimization of the MEMS fabrication process is analyzed. The experimental results show the prototype generates a maximum power density of 2.52mW/cm^2 at room temperature. This performance is better than the published resuits of other silicon-based passive μDMFCs. Moreover,it is comparable with that of our previous active μDMFCs which require an external pump, certificating the feasibility of this new configuration.

阶级、性别、种姓:微观权力视域下《生命之书》的一个解读视角

《生命之书》是印度作家克里希纳·索波蒂对印巴分治之前旁遮普地区乡村生活的全景式描摹,被认为是一部历史小说。这部作品不仅仅是对一个时代的记忆,更是对旁遮普地区特定文化和社会背景的深刻探讨。通过展现旁遮普乡村空间作为权力运行的主要舞台,小说生动地描绘了微观权力如何在公共空间、家庭、个人和心理层面渗透和运作。文章主要运用福柯的权力理论,探讨小说中微观权力的运行,揭示在阶级、性别、种姓等关系场域中权力机制对个体的规训作用,以期更深刻地洞察小说所反映的社会结构、文化背景和权力关系,更全面地理解《生命之书》的文学价值。

面向电力装备自供电传感的微纳能源收集技术

数智化电网的建设依赖于海量分布式电力装备状态监测传感器,提升传感器的供电可靠性进而实现自供电感知,对拓展设备状态感知系统的深度和广度具有重要意义。近年来,以纳米发电机为代表的微纳能源收集方法与器件被广泛关注,其能够将多元、分散的机械能、热能、电磁能等转化为电能,搭配微能量存储元件与低功耗微纳传感器实现自供电传感。该文围绕面向电力装备自供电传感的微纳能源收集方法这一主题,首先介绍了电力装备及其运行环境微能量的分布特性;其次,总结了以热电纳米发电机、摩擦纳米发电机、压电纳米发电机、磁场能收集发电机、水伏发电机为代表的微纳能源收集方法原理及特点,分析了其在电力装备场景下的适用性,同时综述了基于微纳能源器件的电力装备微能量收集与自供电传感最新研究进展,并提出了本领域目前发展面临的主要技术难点和潜在解决方案。最后,展望了微纳能源收集方法及器件的发展趋势,有望为电力装备自供电状态监测和数智化发展提供参考与指导。

Low-Power Operational Amplifier for Real-Time Signal Processing System of Micro Air Vehicle

A low-power complementary metal oxide semiconductor（CMOS） operational amplifier （op-amp） for real-time signal processing of micro air vehicle （MAV） is designed in this paper.Traditional folded cascode architecture with positive channel metal oxide semiconductor（PMOS） differential input transistors and sub-threshold technology are applied under the low supply voltage.Simulation results show that this amplifier has significantly low power,while maintaining almost the same gain,bandwidth and other key performances.The power required is only 0.12 mW,which is applicable to low-power and low-voltage real-time signal acquisition and processing system.

数字关爱抑或媒介控制?老年人视角下智能手机使用中的数字鸿沟

文章以数字鸿沟理论的三个层次为分析框架,理解老年人对于数字设备接入、使用和效果的感知。通过家庭访谈研究发现,在智能手机接入方面,社会中弥散的边缘气氛预设了老年人对新技术较低的需求;在智能手机使用中,年轻人基于代际关系将永远在线气氛传递给老年人进而影响其媒介使用;在智能手机使用效果中,老年人的实际媒介使用效果处于流动变化中,与社会责任、性别关系等要素相关。研究认为,社会以一种看似关爱老年人的方式遮蔽了对老年人媒介使用的控制,老年人自身则受困于家庭资源和亲情需求,不断让渡自身权力。老年人需要从数字社会边缘回归社会中心,以真正弥合银色数字鸿沟。

新能源电动农机一源多用创新供能赋能农网农机融合发展——基于全国536份调查问卷分析

随着我国“三电”技术的快速发展,新能源电动农机也如雨后春笋般迅速崛起,一源多用的提出是解决新能源电动农机季节性闲置、利用率低、无法与农村电网(以下简称农网)新型电力系统互动融合等问题的创新发展模式,具有用能清洁环保、数智化程度高、易于组网的现代化技术特征。针对新能源电动农机一源多用的关键技术、应用场景、实施路径和商业模式等存在问题与发展前景,面向农机、农业、电力和电网等相关从业人员开展网络问卷调研,从一源多用技术发展潜力和农网农机融合认知态势等视角,基于调研结果,研究了一源多用赋能农网农机融合的农机电能替代潜力、应用场景、综合效益等,分析了一源多用的实施路径和商业模式,提出了一源多用创新供能模式赋能农网农机融合的关键技术和扶持政策建议。结果表明,新能源电动农机一源多用发展模式具有较好经济效益和环保效益,发展前景被普遍看好,对落实双碳目标与乡村振兴战略具有积极意义。未来仍需开展新能源电动农机和电网融合互动关键技术协同攻关和应用研究,探索可持续且多方共赢的良性商业模式。

固定床薄膜生物反应器处理农村废水氨氮研究

为解决农村生活污水处理在技术和管理层面的差异性,采用以新型薄膜材料作为微生物载体的微动力固定床薄膜生物法。通过对生物反应器挂膜方法和挂膜后膜卷间隙、进水水力负荷、循环时间、进水污染物负荷等因素的条件下对于氨氮污染物的去除率来确定农村污水排放分级达标要求下的工艺措施和固定床薄膜生物反应器的运行控制参数。研究表明膜卷间隙为5 mm时,装置对氨氮的去除效果较好。在水力负荷为2.82 m^(3)/(m^(2)·h)时,系统对氨氮的去除效果达到最佳。在循环时间为3 h系统对氨氮的去除效果达到最佳。在4种污染物负荷下反应器有较强的扛冲击能力。

脉冲参数主动匹配式micro-EDM脉冲电源

为了提高微细电火花加工(micro-EDM)效率,设计了一种脉冲参数主动匹配式micro-EDM脉冲电源.采用等能量加工的方法,对不同的脉冲匹配参数进行加工效率对比实验,设计了脉冲参数主动匹配式脉冲电源的结构、功能和控制策略,并进行了加工实验验证.结果表明:选定合适的脉宽和脉间参数,使极间电容单次充电和单次放电,可获得最高的加工效率;该电源脉冲参数可根据极间电压和极间电容的大小自动调整;进行微小孔加工,加工连续性较好,加工效率和加工质量较高.利用该电源可进行微细加工,加工效率较传统电源有显著的提升,并能保证较高的加工质量.

考虑新能源出力不确定性的风-光-柴-储系统调度策略

文章以风-光-柴-储系统为研究对象,为了研究新能源出力不确定性对该系统的影响,提出了一种新能源出力复合预测模型。为提高风-光-柴-储系统运行的经济性、环保性和安全性,提出了考虑新能源出力不确定性的风-光-柴-储系统调度模型,并采用了带有Monte Carlo模拟的遗传算法对模型进行求解。文章采用了负荷缺失率(load loss rate,LLR)和置信概率对系统的安全性进行评价,并分析了其对系统调度结果的影响。仿真结果表明,文中所提出的考虑新能源出力不确定性的风-光-柴-储系统调度模型,可以降低新能源出力不确定性对系统的影响,且该方法可以有效地平衡系统的经济性和安全性。

主动匹配式micro-EDM脉冲电源设计与实验

为了提高微细电火花加工(micro-EDM)效率,设计了一种脉冲参数主动匹配式micro-EDM脉冲电源。采用主动匹配式脉冲发生电路实现脉冲参数根据极间电容充放电情况自动匹配,通过实验,对电源的加工效率、加工质量和低电压加工情况进行了分析。结果表明:采用该电源可以实现在单个脉冲周期内,极间电容单次充电、单次放电;与常规晶体管脉冲电源比较,该电源可以提高加工效率,加工表面变质层无裂纹、凹坑均匀、加工质量较高;可以实现24 V低电压加工,加工后的微孔圆度和精度较高。该电源具有提高微细电火花加工效率,保证较高加工质量的作用。