Increasing the Efficiency and Level of Environmental Safety of Pro-Environmental City Heat Supply Technologies by Low Power Nuclear Plants

In connection with the current prospect of decarbonization of coal energy through the use of small nuclear power plants (SNPPs) at existing TPPs as heat sources for heat supply to municipal heating networks, there is a technological need to improve heat supply schemes to increase their environmental friendliness and efficiency. The paper proves the feasibility of using the heat-feeding mode of ASHPs for urban heat supply by heating the network water with steam taken from the turbine. The ratio of electric and thermal power of a “nuclear” combined heat and power plant is given. The advantage of using a heat pump, which provides twice as much electrical power with the same heat output, is established. Taking into account that heat in these modes is supplied with different potential, the energy efficiency was used to compare these options. To increase the heat supply capacity, a scheme with the use of a high-pressure heater in the backpressure mode and with the heating of network water with hot steam was proposed. Heat supply from ASHPs is efficient and environmentally friendly even in the case of significant remoteness of heat consumers.

Assessment of Axial Power Peaking Factors in GHARR-1 LEU Core: A Decadal Simulation Analysis

This study aims to thoroughly investigate the axial power peaking factors (PPF) within the low-enriched uranium (LEU) core of the Ghana Research Reactor-1 (GHARR-1). This study uses advanced simulation tools, like the MCNPX code for analysing neutron behavior and the PARET/ANL code for understanding power variations, to get a clearer picture of the reactor’s performance. The analysis covers the initial six years of GHARR-1’s operation and includes projections for its whole 60-year lifespan. We closely observed the patterns of both the highest and average PPFs at 21 axial nodes, with measurements taken every ten years. The findings of this study reveal important patterns in power distribution within the core, which are essential for improving the safety regulations and fuel management techniques of the reactor. We provide a meticulous approach, extensive data, and an analysis of the findings, highlighting the significance of continuous monitoring and analysis for proactive management of nuclear reactors. The findings of this study not only enhance our comprehension of nuclear reactor safety but also carry significant ramifications for sustainable energy progress in Ghana and the wider global context. Nuclear engineering is essential in tackling global concerns, such as the demand for clean and dependable energy sources. Research on optimising nuclear reactors, particularly in terms of safety and efficiency, is crucial for the ongoing advancement and acceptance of nuclear energy.

Low-noise,low-power-consumption seafloor vector magnetometer

The seafloor vector magnetometer is an effective tool for marine geomagnetic surveys and seafloor magnetotelluric(MT)detection.However,the noise,power consumption,cost,and volume characteristics of existing seafloor vector magnetometers are insufficient for practical use.Therefore,a low-noise,low-power-consumption seafloor vector magnetometer that can be used for data acquisition of deep-ocean geomagnetic vector components is developed and presented.A seafloor vector magnetometer mainly consists of a fluxgate sensor,data acquisition module,acoustic release module,glass sphere,frame,burn-wire release,and anchor.A new low-noise data acquisition module and a fluxgate sensor greatly reduce power consumption.Furthermore,compact size is achieved by integrating an acoustic telemetry module and replacing the acoustic release with an external burn-wire release.The new design and magnetometer characteristics reduce the volume of the instrument and the cost of hardware considerably,thereby improving the integrity and deployment efficiency of the equipment.Theoretically,it can operate for 90 days underwater at a maximum depth of 6000 m.The seafloor vector magnetometer was tested in the South China Sea and the Philippine Sea and obtained high-quality geomagnetic data.The deep-water environment facilitates magnetic field data measurements,and the magnetometer has an approximate noise level of 10 pT/rt(Hz)@1 Hz,a peak-to-peak value error of 0.2 nT,and approximate power consumption of 200 mW.The fluxgate sensor can measure the magnetic field in the lower frequency band and realize geomagnetic field measurements over prolonged periods.

Improved RF power performance of InAlN/GaN HEMT by optimizing rapid thermal annealing process for high-performance low-voltage terminal applications

Improved radio-frequency(RF)power performance of InAlN/GaN high electron mobility transistor(HEMT)is achieved by optimizing the rapid thermal annealing(RTA)process for high-performance low-voltage terminal applications.By optimizing the RTA temperature and time,the optimal annealing condition is found to enable low parasitic resistance and thus a high-performance device.Besides,compared with the non-optimized RTA HEMT,the optimized one demonstrates smoother ohmic metal surface morphology and better heterojunction quality including the less degraded heterojunction sheet resistance and clearer heterojunction interfaces as well as negligible material out-diffusion from the barrier to the channel and buffer.Benefiting from the lowered parasitic resistance,improved maximum output current density of 2279 mA·mm^(-1)and higher peak extrinsic transconductance of 526 mS·mm^(-1)are obtained for the optimized RTA HEMT.In addition,due to the superior heterojunction quality,the optimized HEMT shows reduced off-state leakage current of 7×10^(-3)mA·mm^(-1)and suppressed current collapse of only 4%,compared with those of 1×10^(-1)mA·mm^(-1)and 15%for the non-optimized one.At 8 GHz and V_(DS)of 6 V,a significantly improved power-added efficiency of 62%and output power density of 0.71 W·mm^(-1)are achieved for the optimized HEMT,as the result of the improvement in output current,knee voltage,off-state leakage current,and current collapse,which reveals the tremendous advantage of the optimized RTA HEMT in high-performance low-voltage terminal applications.

基于NB-IoT的智慧健康监测系统设计

人口老龄化导致慢性非传染性的患病率会越来越高,智慧健康养老成为国家应对老龄化的战略目标。针对我国目前的人口结构现状,提出一种基于窄带物联网技术(NB-IoT)的智慧健康监测系统。该系统结合NB-IoT技术、传感器技和软件技术,系统主要包括可穿戴数据采集终端、云服务平台、远程监测平台等3部分。数据采集终端以STM32作为主控制器,实现对用户生理信息的采集,通过NB-IoT网络传输到云平台上,通过远程监测平台实现健康的远程监测,对健康问题进行预警。实验结果表明:系统可以实时采集老年人的生理信息(血压、血氧、心率)、运动轨迹以及定位信息,对老年人进行实时全方位健康监控,提前预防并降低慢性疾病发病率、减小死亡率、延长寿命。

基于NB-IoT的地下管廊环境监测系统设计

城市地下管廊内布设了大量的管线,如燃气管道、网络通讯线路、电力线路等,由于地下环境复杂多变,存在着气体泄漏、爆炸、火灾等安全风险。针对这些问题,提出一种基于窄带物联网技术(Narrow Band Internet of Things,NB-IoT)的地下管廊环境监测系统。该系统采用先进的传感器技术、NB-IoT技术、软件技术,系统主要分为数据采集模块、物联网云平台、远程监测系统三部分。数据采集模块以STM32作为主控单元连接各个传感器,采集温度、湿度、水位、可燃气体等数据,经过处理后利用NB-IoT网络上传到物联网云平台,远程监测系统调用物联网云平台的数据接口进行远程显示与预警。实验结果表明,系统在降低系统总体功耗的同时,能够实时、稳定地进行地下管廊环境监测,提前预防可能存在的风险。

一种基于NB-IoT的智能井盖监测系统设计

针对城市井盖保有量大、安全事故频发、人工巡检困难、管理组织混乱等问题,提出一种基于窄带物联网(NB-IoT)技术的窨井盖自动监测系统。该系统以STM32作为主控模块,包含倾角、水位等传感器,实现对井盖状态以及井内重点数据的采集,配合云端服务器和客户端完成井盖数据远程可视化显示。结果表明,所提系统可以实现故障井盖自动报警、精确定位,降低人工巡检的难度,让城市井盖管理更加智能化,让故障检修更加便捷化,提高城市管理的智能化水平。

基于VC-综合赋权法的海上风电APF配置优化方法研究

大容量海上风电机组的接入改变了传统电力系统结构,给电网带来了谐波等问题,影响了电能质量。为抑制海上风电机组产生的低次谐波,文章首先建立了海上风电机组并网电流的低次谐波理论模型;然后,在仿真软件ETAP上搭建海上风电机组仿真模型,验证不同出力情况下风电场的输出谐波特性;最后,基于风电场输出谐波特性,提出变异系数(Variation Coefficient,VC)综合赋权法对风电场有源滤波器(APF)进行优化配置,提升了风电场谐波的治理效果。基于实际算例验证了所提方法的有效性。

阶梯碳下考虑耦合电转气-碳捕集和热电联产灵活输出的综合能源系统优化调度

“双碳”目标下,为进一步降低综合能源系统(integrated energy system,IES)碳排放,提升可再生能源消纳能力,提出一种IES低碳经济运行优化策略。首先引入阶梯型碳交易机制约束IES的碳排放;然后建立耦合电转气(power to gas,P2G)和碳捕集系统(carbon capture system,CCS)模型,并细化P2G两阶段运行;接着在传统热电联产机组(combined heat and power,CHP)中引入卡琳娜循环与电锅炉联合运行,构造热电灵活输出的CHP模型;最后以系统运维成本、碳交易成本、购能成本和弃风弃光成本之和最小为优化目标,构建IES低碳经济调度模型,并设置不同运行场景对比分析。结果表明:IES碳排放减少38.45%,运行总成本降低10.37%,验证了所建模型的低碳性和经济性。

LCC-MMC混合三端直流输电系统送端交流故障下的不间断运行协调控制策略

为实现基于电网换相换流器与模块化多电平换流器(LCC-MMC)的混合三端直流输电系统送端交流故障下的直流低电压穿越,提出兼顾传输容量与响应速度的自适应电压协调控制策略及有功功率分配策略。在维持故障期间功率续传的前提下,定量分析了模块化多电平换流器(MMC)的降压值以减少传输功率的绝对值损失量,并设计MMC根据本地直流电流偏差快速减投子模块总数的降压方式;考虑到半桥型MMC的调制比约束,设计正极MMC定量吸收无功功率与负极MMC动态调整交流电压参考值的换流站极间协同控制策略;同时,为抑制从站的过电流及避免送端严重交流故障时主站的潮流反转,提出各受端换流站有功功率自适应调整的控制方式。最后通过对输电系统送端交流电压跌落不同幅度时的故障穿越效果进行仿真分析,验证了所提控制策略的有效性。

煤流-潮流协同的矿山供电系统低碳优化运行

双碳目标的提出对我国矿山绿色高效开采提出了更高的需求。为此,该文提出煤流-潮流协同的矿山供电系统优化调度方法。首先,基于煤流在采煤工作面、带式运输机、储煤筒仓等环节的连续性特征,抽象出运输煤流和节点功率耦合的运输设备模型;其次,整合煤流运输安全约束与配网潮流约束,建立煤流-潮流协同的运行优化模型;最后,以矿山用能的经济性和碳减排为目标,考虑主网实时碳计量水平,调节采煤时间、煤流速度、运输流量与设备用能,生成煤流运输和矿山电网低碳调度的优化方案。以山西某矿山供电系统为实例,验证所提模型与方法的有效性。仿真结果表明,所提模型与方法能够有效降低矿山生产的吨煤电耗、用能成本及碳排放量,实现了煤流-潮流协同的矿山低碳化经济运行。

基于小脑模型-模糊滑模控制的电力系统低频振荡控制策略研究

由于现代电力系统互联规模不断增大,柔性控制系统加入和长距离输电使得电网阻尼不断减小,运行方式的多变性不断改变系统潮流分布,极易引发低频振荡现象。针对此问题,该文提出一种基于小脑模型关节误差修正的模糊滑模附加阻尼控制策略。首先在模糊滑模控制(fuzzy sliding mode control,FSMC)的基础上,引入小脑模型关节控制(cerebellar model articulation control,CMAC)理论,构建CMAC-FSMC算法,提高滑模趋近阶段模糊逻辑对系统的补偿能力,最大程度提高系统稳定性能;其次通过构造CMAC-FSMC的调整指标与总控制率,减小控制误差,提高控制性能;最后通过线性降阶方法建立被控系统模型并确定区间振荡模态,采用几何测度法选择最佳反馈信号和安装位置,基于所提出的CMAC-FSMC方法进行广域阻尼控制器设计。通过对10机39节点系统进行仿真验证,结果表明CMAC-FSMC控制策略能够有效提高系统阻尼,显著抑制低频振荡。

考虑电压-无功调节的台区互联装置规划方法

伴随分布式能源广泛接入低压配电网,其对配电网运行灵活性和消纳能力的要求不断提高。利用低压柔性互联装置将独立运行的低压配电台区分区互联,避免传统电压调节和无功补偿装置频繁动作。考虑到柔性互联装置造价昂贵,协同传统电压-无功调节装置,文中提出低压柔性互联装置的选址定容规划方法。首先,分析低压柔性互联装置拓扑和运行方式,建立其潮流模型。其次,建立低压柔性互联装置优化配置的双层规划模型,上层规划以年综合费用最小为目标,下层规划考虑电压-无功协调控制时间序列模型,以运行成本和电压偏差最小为目标,基于粒子群优化算法和混合整数二阶锥规划算法交替求解,得出配电系统最优柔性互联方案和最优运行方式。最后,在IEEE 33节点系统上进行实例分析,验证该双层规划算法的有效性。结果表明,所提方法能有效减少柔性互联装置的过度布置,同时减少由分布式能源频繁波动造成的运行成本。将模型凸化并线性化的方法明显提高了求解效率。

用于Pipelined-SAR模数转换芯片中的高精度比较器设计

设计了一款可用于18 bit、2 Ms/s的流水线型逐次逼近型模数转换器(Pipelined-SAR ADC)的高精度比较器,该比较器的结构为三级预放大器+锁存器(latch),同时采用了一种失调电压消除技术,有效减小了比较器的失调电压。在TSMC 0.18μm的工艺下,使用Spectre对比较器进行仿真,结果表明,该比较器在1.8 mW的功耗下,输入失调电压标准差为131μV,噪声电压为15μV,满足高精度和低功耗的要求。

Low-power laser irradiation promotes the proliferation and osteogenic differentiation of human periodontal ligament cells via cyclic adenosine monophosphate

Retaining or improving periodontal ligament （PDL） function is crucial for restoring periodontal defects. The aim of this study was to evaluate the physiological effects of low-power laser irradiation （LPLI） on the proliferation and osteogenic differentiation of human PDL （hPDL） cells. Cultured hPDL cel Is were irradiated （660 nm） daily with doses of O, 1, 2 or 4 J .cm-2. Cell proliferation was evaluated by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide （MTT） assay, and the effect of LPLI on osteogenic differentiation was assessed by Alizarin Red S staining and alkaline phosphatase （ALP） activity. Additionally, osteogenic marker gene expression was confirmed by real-time reverse transcription-polymerase chain reaction （RT-PCR）. Our data showed that LPLI at a dose of 2 J.cm-2 significantly promoted hPDL cell proliferation at days 3 and 5. In addition, LPLI at energy doses of 2 and 4 J.cm-2 showed potential osteogenic capacity, as it stimulated ALP activity, calcium deposition, and osteogenic gene expression. We also showed that cyclic adenosine monophosphate （cAMP） is a critical regulator of the LPLI-mediated effects on hPDL cells. This study shows that LPLI can promote the proliferation and osteogenic differentiation of hPDL cells. These results suggest the potential use of LPLI in clinical applications for periodontal tissue regeneration.

Low power consumption 4-channel variable optical attenuator array based on planar lightwave circuit technique

The power consumption of a variable optical attenuator（VOA） array based on a silica planar lightwave circuit was investigated. The thermal field profile of the device was optimized using the finite-element analysis. The simulation results showed that the power consumption reduces as the depth of the heat-insulating grooves is deeper, the up-cladding is thinner,the down-cladding is thicker, and the width of the cladding ridge is narrower. The materials component and thickness of the electrodes were also optimized to guarantee the driving voltage under 5 V. The power consumption was successfully reduced to as low as 155 mW at an attenuation of 30 dB in the experiment.

改进TDM-LoRa低功耗森林火灾监测预警系统

针对目前森林火灾监测系统成本高、功耗大、维护复杂的缺点,提出一种基于改进TDM-LoRa设计的低功耗森林火灾监测预警系统.系统以STM32系列微处理器为节点控制核心,LoRa-SX1278芯片为通信模块,并使用增量传输和改进时分复用通信机制,有效降低节点能耗,从而延长监测节点和汇聚节点寿命.试验结果表明,数据信息在发射功率为20 dBm、传输速率为1.2 kbit·s^(-1)的情况下,节点在3500 m范围内实现的丢包率仅为7.2%;在使用2600 mA·h的电池、数据采集上传间隔时间为30 min的情况下,单个节点有效工作时间理论可达90.7个月,实现无中继远距离低功耗森林环境监测数据的采集.

Modelling Study to Compare the Flow and Heat Transfer Characteristics of Low-Power Hydrogen,Nitrogen and Argon Arc-Heated Thrusters

A modelling study is performed to compare the plasma flow and heat transfer characteristics of low-power arc-heated thrusters （arcjets） for three different propellants： hydrogen, nitrogen and argon. The all-speed SIMPLE algorithm is employed to solve the governing equations, which take into account the effects of compressibility, Lorentz force and Joule heating, as well as the temperature- and pressure-dependence of the gas properties. The temperature, velocity and Mach number distributions calculated within the thruster nozzle obtained with different propellant gases are compared for the same thruster structure, dimensions, inlet-gas stagnant pressure and arc currents. The temperature distributions in the solid region of the anode-nozzle wall are also given. It is found that the flow and energy conversion processes in the thruster nozzle show many similar features for all three propellants. For example, the propellant is heated mainly in the near-cathode and constrictor region, with the highest plasma temperature appearing near the cathode tip; the flow transition from the subsonic to supersonic regime occurs within the constrictor region; the highest axial velocity appears inside the nozzle; and most of the input propellant flows towards the thruster exit through the cooler gas region near the anode-nozzle wall. However, since the properties of hydrogen, nitrogen and argon, especially their molecular weights, specific enthMpies and thermal conductivities, are different, there are appreciable differences in arcjet performance. For example, compared to the other two propellants, the hydrogen arcjet thruster shows a higher plasma temperature in the arc region, and higher axial velocity but lower temperature at the thruster exit. Correspondingly, the hydrogen arcjet thruster has the highest specific impulse and arc voltage for the same inlet stagnant pressure and arc current. The predictions of the modelling are compared favourably with available experimental results.

Transplantation of low-power laser-irradiated olfactory ensheathing cells to promote repair of spinal cord injury in rats

BACKGROUND： Previous studies have demonstrated that low-power laser （LPL） irradiation can promote the regeneration of peripheral nerves and central nerves, as well as influence cellular proliferation. Therefore, it is thought to be a potential treatment for spinal cord injury. OBJECTIVE： Utilizing histological observations and behavioral evaluations, the aim of this study was to investigate the influence of transplanted olfactory ensheathing cells （OECs）, irradiated by LPL, on functional repair of rats following transversal spinal cord injury. DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment was performed at the animal experimental center in the First Affiliated Hospital of Xinjiang Medical University between January 2007 and February 2008. MATERIALS： A total of 52 Sprague Dawley rats were included in this experiment. Twelve rats were used to harvest OECs, some of which were irradiated by LPL on days 3, 5, and 7 in culture. The remaining 40 rats were used to establish T12 complete spinal cord transection injury. DMEM/F12 medium was purchased from Sigma, USA, Fluorogold was provided by Chemicon, USA, and the LY/JG650-D500-16 low-power laser was produced by Xi＇an Lingyue Electromechanical Science And Technology Co., Ltd., China. METHODS： The successful rat models were randomly divided into three groups： OEC transplantation, LPL-irradiated OEC transplantation, and control. These animals were microinjected with OEC suspension, LPL-irradiated OEC suspension, and DMEM/F12 medium （10μL） respectively 4 weeks after spinal cord was completely transected at the T12 level. MAIN OUTCOME MEASURES： Spinal cord injury was observed using hematoxylin-eosin staining Expression of nerve growth factor receptor p75 and glial fibrillary acidic protein were determined using immunohistochemical staining. Regeneration of spinal nerve fibers in rats was assayed by Fluorogold retrograde labeling method. Basso, Beattie and Bresnahan （BBB） scores were used to evaluate motor functions of rat lower limbs. RESULTS： Structural disturbances were observed following spinal cord injury in each group, and a large amount of scar tissue covered the broken ends, accompanied by porosis and inflammatory cell infiltration. Following OEC transplantation, the distal end connected to the proximal end. nerve growth factor receptor p75 and glial fibrillary acidic protein immunohistochemistry revealed positive OECs in the cephalad and caudal area of rats that received LPL-irradiated OEC transplantation. In the OECs group, only glial fibrillary acidic protein staining was observed. No staining was found in the control group. Neural fibers labeled with Fluorogold extended across the lesion area and into the cephalad and caudal area in the OECs and LPL-irradiated OECs groups, but were not present in the control group. BBB scores revealed statistically significant differences among the three groups （P 〈 0.05）： OECs irradiated by LPL group 〉 OECs group 〉 control group. CONCLUSION： Transplantation of OECs and LPL-irradiated OECs promoted functional repair in the injured spinal cord of rats, although LPL-irradiated OECs resulted in greater beneficial effects.

A low-power high-throughput link splitting router for NoCs

In this paper, we propose a technique for lowering the latency of the communication in a NoC (network on chip). The technique, which can support two qualities of service (QoS), i.e., the guaranteed throughput (GT) and best effort (BE), is based on splitting a wider link into narrower links to increase throughput and decrease latency in the NoC. In addition, to ease the syn-chronization and reduce the crosstalk, we use the 1-of-4 encoding for the smaller buses. The use of the encoding in the proposed NoC architecture considerably lowers the latency for both BE and GT packets. In addition, the bandwidth is increased while the power consumption of the links is reduced.