SmartMicro Grid Energy System Management Based on Optimum Running Cost for Rural Communities in Rwanda

The governmental electric utility and the private sector are joining hands to meet the target of electrifying all households by 2024.However,the aforementioned goal is challenged by households that are scattered in remote areas.So far,Solar Home Systems(SHS)have mostly been applied to increase electricity access in rural areas.SHSs have continuous constraints to meet electricity demands and cannot run income-generating activities.The current research presents the feasibility study of electrifying Remera village with the smart microgrid as a case study.The renewable energy resources available in Remera are the key sources of electricity in that village.The generation capacity is estimated based on the load profile.The microgrid configurations are simulated with HOMER,and the genetic algorithm is used to analyze the optimum cost.By analyzing the impact of operation and maintenance costs,the results show that the absence of subsidies increases the levelized cost of electricity(COE)five times greater than the electricity price from the public utility.The microgrid made up of PV,diesel generator,and batteries proved to be the most viable solution and ensured continuous power supply to customers.By considering the subsidies,COE reaches 0.186$/kWh,a competitive price with electricity from public utilities in Rwanda.

A fast-running method for blast load prediction shielding by a protective barrier

This study presents a simplified blast load prediction method on structures behind a protective barrier.The proposed method is basically an empirical approach based on Kingery-Bulamsh(K-B)chart and finite element(FE)analysis results.To this end,this study divides the structure into three regions by three critical points.Blast loads at each critical point can be calculated based on K-B chart and an approximation according to FE analysis results.Finally,peak reflected overpressure and impulse distributed on the structure can be approximately estimated by linearly connecting blast loads at each critical point.In order to confirm a feasibility of the proposed method,a series of numerical simulations were carried out.The simulation results were compared with FE analysis results which are presented in the open literature.From such comparisons,it was found that the proposed method is applicable to predict blast loads on structures behind a protective barrier.

基于Mask R-CNN的电力关键设备运行状态检测

为判断电力关键设备两端负载电压与干路总电压之间的数值关系,提出基于Mask R-CNN的电力关键设备运行状态检测方法。在Mask R-CNN网络结构中,判断电量信号的时域范围与频域范围。然后根据负荷阻抗特征计算交流参数的取值结果,再联合已获取的电信号参量,求解连续相关函数,从而检测电力关键设备运行状态。实验过程中,设备两端负载电压、内阻消耗电压之和与干路总电压之间的差值未超过1.5 V,说明该方法能够证明电力关键设备两端负载电压、内阻消耗电压之和等于干路总电压数值的猜想成立,可以根据该验证检测电力关键设备运行状态是否正常。

早老素-1基因启动子区-48C/T位点多态性与LOAD的遗传相关性

目的 研究早老素 - 1基因启动子区 - 4 8C/T位点的多态性与迟发性AD(LOAD)的相关性。方法 用常规方法从人外周血白细胞中抽提基因组DNA ,PCR扩增出包含 - 4 8C/T多态性位点的基因片段 ,利用PCR -RFLP技术对 -4 8C/T多态性位点进行基因分型 ,χ2 检验分析 - 4 8C/T多态性位点基因型分布和等位基因频率。结果 以 33例AD病例和32例对照样品的外周血白细胞基因组DNA为模板 ,PCR扩增出了长度为 344bp的包含 - 4 8C/T多态性位点的基因片段。基因分型结果表明 ,33例散发型AD的C和T等位基因频率分别为 4 7%和 5 3% ,C/T和T/T基因型频率分别为 94 %和 6 %。而 32例正常对照的C和T等位基因频率分别为 4 8%和 5 2 % ,C/T和T/T基因型频率分别为 97%和 3%。χ2 检验结果显示 ,病例 -对照样品间C和T等位基因频率及C/C、C/T和T/T基因型的分布均无显著性差异 (χ2 值分别为 0 4 4 3和 0 318,P>0 .0 5 )。结论 在我们研究的群体中 ,早老素 - 1基因启动子区 - 4 8C/T位点的多态性与LOAD无显著的遗传相关性。

Reduction in ground reaction force variables with instructed barefoot running

Backgound:Barefoot(BF) running has recently increased in popularity with claims that it is more natural and may result in fewer injuries due to a reduction in impact loading.However,novice BF runners do not necessarily immediately switch to a forefoot strike pattern.This may increase mechanical parameters such as loading rate,which has heen associated with certain running-related injuries,specifically,tibial stress fractures.patellofemoral pain,and plantar iasciitis.The purpose of this study was to examine changes in loading parameters between typical shod running and instructed BF running with real-time force feedback.Methods:Forty-nine patients seeking treatment for a lower extremity injury ran on a force-sensing treadmill in their typical shod condition and then BF at the same speed.While BF they received verbal instruction and real-time feedback of vertical ground reaction forces.Results:While 92%of subjects(n = 45) demonstrated a rearfoot strike pattern when shod,only 2%(n = 1) did during the instructed BF run.Additionally,while BF 47%(n = 23) eliminated the vertical impact transient in all eight steps analyzed.All loading variables of interest were significantly reduced from the shod to instructed BF condition.These included maximum instantaneous and average vertical loading rates of the ground reaction force(p 【 0.0001),stiffness during initial loading(p 【 0.0001).and peak medial(p = 0.001) and lateral(p 【 0.0001) ground reaction forces and impulses in the vertical(p 【 0.0001).medial(p = 0.047),and lateral(p 【 0.0001) directions.Conclusion:As impact loading has been associated with certain running-related injuries,instruction and feedback on the proper forefoot strike pattern may help reduce the injury risk associated with transitioning to BF running.

Topology optimization of 3D structures with design-dependent loads

Topology optimization of continuum structures with design-dependent loads has long been a challenge. In this paper, the topology optimization of 3D structures subjected to design-dependent loads is investigated. A boundary search scheme is proposed for 3D problems, by means of which the load surface can be identified effectively and efficiently, and the difficulties arising in other approaches can be overcome. The load surfaces are made up of the boundaries of finite elements and the loads can be directly applied to corresponding element nodes, which leads to great convenience in the application of this method. Finally, the effectiveness and efficiency of the proposed method is validated by several numerical examples.

Effect of Run - in Ratios on the Mechanical Properties of Two - Guide Bars Warp - Knitted Fabrics

Warp knitting technology gets rapid development at present and becomes one of the most important parts of the textiles.But it is less known how the parameters of warp knitting technology affect the mechanical properties of warp-knitted fabrics.This paper presents discuss a research on the relationships between run-in ratio and mechanical properties of the two-bar warp-knittedfabrics through the measurement and analysis of the mechanical properties of various samples with different run-in ratios.The optimal run一in ratios for the reasonable mechanical properties are obtained from above dis-

Numerical study on wave loads and motions of two ships advancing in waves by using three-dimensional translating-pulsating source

A frequency domain analysis method based on the three-dimensional translating-pulsating （3DTP） source Green function is developed to investigate wave loads and free motions of two ships advancing on parallel course in waves. Two experiments are carried out respectively to mea- sure the wave loads and the free motions for a pair of side-by- side arranged ship models advancing with an identical speed in head regular waves. For comparison, each model is also tested alone. Predictions obtained by the present solution are found in favorable agreement with the model tests and are more accurate than the traditional method based on the three dimensional pulsating （3DP） source Green function. Numer- ical resonances and peak shift can be found in the 3DP pre- dictions, which result from the wave energy trapped in the gap between two ships and the extremely inhomogeneous wave load distribution on each hull. However, they can be eliminated by 3DTP, in which the speed affects the free sur- face and most of the wave energy can be escaped from the gap. Both the experiment and the present prediction show that hydrodynamic interaction effects on wave loads and free motions are significant. The present solver may serve as a validated tool to predict wave loads and motions of two ves- sels under replenishment at sea, and may help to evaluate the hydrodynamic interaction effects on the ships safety in replenishment operation.

Large deflections of non-prismatic nonlinearly elastic cantilever beams subjected to non-uniform continuous load and a concentrated load at the free end

This work studies large deflections of slen- der, non-prismatic cantilever beams subjected to a combined loading which consists of a non-uniformly distributed con- tinuous load and a concentrated load at the free end of the beam. The material of the cantilever is assumed to be non- linearly elastic. Different nonlinear relations between stress and strain in tensile and compressive domain are considered. The accuracy of numerical solutions is evaluated by com- paring them with results from previous studies and with a laboratory experiment.

Effect of Mild-calcined Coal Gangue Additionon Hot Strength and Refractoriness Under Loadof Ultra Low Cement Castablesin Al_2O_3-SiO_2 System

This work explored the way to improve hot modulus q/＇ rupture （HMOR） and refractoriness under load （RUL） by adding mild-calcined coal gangue （MCG） in Al2O3 -SiO2 ultra low cement （ULC） castables, making use of the in-situ effect of the MCG during heating-up. The influence of respective additions of 5%, 10% and 1.5% of the MCG powders calcined at 700℃ was investigated on HMOR at 1400 ℃ and RUL of the castables. With increased addition of the MCG, HMOR and RUL become significantly enhanced. At 10% of the MCG addition, HMOR reaches 3 MPa, as compared to 0. 3 MPa in the case of no MCG addition. RUL of the specimens dried at 110 ℃for 24 h can be increased by some 270 ℃ with 10% of the MCG addition. RUL 0.11 the specimens preheated at 1 500℃ for 3 h maintains the growth trend with the MCG addition increasing. The microstructure of the heated castable samples was investigated by means of SEM. The in-situ formed needle-like and interlaced mullite in the matrix is contributive to the tmprovement.

Non-stationary Buffeting Response Analysis of Long Span Suspension Bridge Under Strong Wind Loading

The non-stationary buffeting response of long span suspension bridge in time domain under strong wind loading is computed. Modeling method for generating non-stationary fluctuating winds with probabilistic model for non-stationary strong wind fields is first presented. Non-stationary wind forces induced by strong winds on bridge deck and tower are then given a brief introduction. Finally,Non-stationary buffeting response of Pulite Bridge in China,a long span suspension bridge,is computed by using ANSYS software under four working conditions with different combination of time-varying mean wind and time-varying variance. The case study further confirms that it is necessity of considering non-stationary buffeting response for long span suspension bridge under strong wind loading,rather than only stationary buffeting response.

Operational Wave Now- and Forecast in the German Bight as a Basis for the Assessment of Wave-Induced Hydrodynamic Loads on Coastal Dikes

The knowledge of the wave-induced hydrodynamic loads on coastal dikes including their temporal and spatial resolution on the dike in combination with actual water levels is of crucial importance of any risk-based early warning system. As a basis for the assessment of the wave-induced hydrodynamic loads, an operational wave now-and forecast system is set up that consists of i) available field measurements from the federal and local authorities and ii) data from numerical simulation of waves in the German Bight using the SWAN wave model. In this study, results of the hindcast of deep water wave conditions during the winter storm on 5–6 December, 2013(German name ‘Xaver') are shown and compared with available measurements. Moreover field measurements of wave run-up from the local authorities at a sea dike on the German North Sea Island of Pellworm are presented and compared against calculated wave run-up using the Eur Otop(2016) approach.

基于货-车-轨耦合动力学分析的重车重心高度及管控规则研究

我国现行重车重心高度管控规则已凸显限制铁路货运系统运输能力的矛盾。针对此问题,通过深度剖析货物-车体耦合机制,建立货-车-轨耦合动力学模型,并采用动态Nadal限度评估车辆运行脱轨风险,基于模型仿真分析我国铁路通用货车在正常速度运行时应限制的重车重心限制高度,以及重心高度超过该限值时的相应限速规定。研究结果表明:针对货物装载参数影响车辆动力学行为的研究,动态Nadal限度可有效减小脱轨误判率,相比于经典Nadal限度更适宜作为脱轨风险的评判依据;基于动态Nadal限度判定车辆脱轨风险,我国铁路通用货车的重车重心限制高度可提升至2400 mm;在保证车辆运行安全的前提下,重心超高时的区间限速规定可以合理地适当放宽。

具有变超越负载的液压调平系统负载口独立控制方法

液压调平系统平台回落过程中存在超越负载,且随着负载重心偏移和平台倾角变化,作用于支腿液压缸的负载力也会随之变化。传统液压系统中负载控制阀或平衡阀在平衡变超越负载时速度控制效果差,容易发生速度抖动。为解决这一问题,采用负载口独立控制技术,针对平台回落时液压缸存在的变超越负载工况,提出对液压调平系统中液压缸有杆腔进行压力控制,无杆腔进行流量控制的压力-流量复合控制方法,建立其数学模型,并进行AMESim和Simulink联合仿真验证。结果表明,在负载力发生突变时,液压缸有杆腔压力和无杆腔流量均可在0.2 s内恢复至控制值,平衡掉系统变超越负载的同时,能够满足系统的速度控制需求。

高校高水平女子足球运动员比赛跑动表现特征研究

目的:探讨中国高校高水平女足运动员在运动员排名、位置和比赛时间变化下的足球比赛跑动表现的特征和模式.方法:收集采用GPS可穿戴设备参加中国2020—2021年全国青年校园足球联盟(大学女子超级冠军联赛)的75支球队和393名球员的跑步数据,并对他们在不同比赛、不同位置和不同时期的跑步特征进行比较和分析.结果:①与上半场相比,下半场球员的比赛负荷数据呈下降趋势,上半场和下半场之间存在差异(P<0.01),且存在明显的位置特征.②上半场不同时期的球员跑动能力表现出“W”型特征,下半场表现出“M”型特征,上半场跑动表现一致,下半场有所下降.③上半场前、中、后卫球员在低速、中速、快速跑等方面存在差异(P<0.05),但下半场在高强度区的位置没有差异.球员有低强度的跑动,并在较短的时间内保持高强度的跑动,前后球员在这个指标上优于中场.结论:①比赛中高强度跑动占比较低,相应来讲,低速跑动与中速跑动跑距占比明显增加,同时跑动距离较短,主要表现出运动员的磷酸原和糖酵解系统能量供应与足球比赛所需存在一定的差距.②高强度的跑动距离偏少,中低强度跑距占比的增加反映了比赛中运动员体能恢复所需时间的增加.

中等负荷跑台训练对D-半乳糖致衰老大鼠基底前脑-皮质自由基代谢的影响

目的:观察中等负荷跑台训练对D-半乳糖致衰老大鼠基底前脑、海马结构和皮质自由基代谢的影响。方法:将30只大鼠随机分为正常对照组、衰老模型对照组和衰老模型中等负荷训练组,每组10只,6周后,用Morris水迷宫试验进行学习记忆能力的测定,然后检测基底前脑、海马结构和大脑皮质NO、丙二醛(MDA)的含量,同时测定超氧化物歧化酶(SOD)的活性。结果:衰老模型组基底前脑、海马结构和大脑皮质NO、MDA含量分别较正常对照组显著增高,而SOD活性显著降低(P<0.01);衰老模型中等负荷训练组基底前脑、海马结构和大脑皮质NO、MDA含量分别较衰老模型组明显降低;而SOD活性明显增高(P<0.05);Morris水迷宫试验结果:正常对照组潜伏期显著短于衰老模型组(P<0.01),衰老模型中等负荷训练组潜伏期显著短于衰老模型对照组(P<0.05)。结论:中等负荷跑台训练可通过提高基底前脑海马/大脑皮质系统SOD的活性,减少NO、MDA的生成,达到清除自由基,抗氧化进而延缓衰老的作用。

内燃机缸套-活塞环磨合过程中微凸体承载研究

为获得内燃机缸套-活塞环磨合磨损过程中微凸体的承载情况,利用粗糙峰的接触模型推导出磨合过程中微凸体承载方程,其中对弹性变形部分微凸体承载和塑性变形部分微凸体承载分别进行了研究,重点比较了内燃机缸套-活塞环磨合过程中假定接触微凸体全部为弹性变形与考虑接触微凸体产生弹、塑性变形时承载能力的不同.研究结果表明,在磨合磨损的中后期,即当h/σ大于0.5,ψ小于0.9时,两者差别不大,可以假定微凸体变形全部为弹性变形进行微凸体载荷的计算;而在磨合磨损初期,即当h/σ小于0.5,ψ大于0.9时,假定微凸体变形全部为弹性变形时的承载为考虑弹、塑性变形时的50%～85%左右.考虑到内燃机缸套-活塞环磨合过程中初期磨合的重要性,在计算缸套-活塞环磨合过程中微凸体承载时,应将塑性变形部分微凸体和弹性变形部分微凸体承载分别进行研究.也说明了本文所建立的微凸体承载方程更有益于缸套-活塞环磨合过程的摩擦学状态分析.

有轨运行式起重机车轮许用载荷计算

有轨运行式起重机车轮许用载荷都是按照GB/T 3811—2008《起重机设计规范》中给出的公式进行计算的,为了让从事起重机设计的专业人员更加深入理解计算公式,详细介绍了计算公式的整个推导过程,并根据铸造起重机大车运行机构的工作特点,提出一个简化后的计算公式,方便设计人员使用。

Conservation genomics provides insights into genetic resilience and adaptation of the endangered Chinese hazelnut, Corylus chinensis

Global climate change has increased concerns regarding biodiversity loss.However,many key conservation issues still required further research,including demographic history,deleterious mutation load,adaptive evolution,and putative introgression.Here we generated the first chromosome-level genome of the endangered Chinese hazelnut,Corylus chinensis,and compared the genomic signatures with its sympatric widespread C.kwechowensis-C yunnanensis complex.We found large genome rearrangements across all Corylus species and identified species-specific expanded gene families that may be involved in adaptation.Population genomics revealed that both C.chinensis and the C.kwechowensis-C.yunnanensis complex had diverged into two genetic lineages,forming a consistent pattern of southwestern-northern differentiation.Population size of the narrow southwestern lineages of both species have decreased continuously since the late Miocene,whereas the widespread northern lineages have remained stable(C.chinensis) or have even recovered from population bottlenecks(C.kwechowensis-C.yunnanensis complex) during the Quaternary.Compared with C.kwechowensis-C. yunnanensis complex,C.chinensis showed significantly lower genomic diversity and higher inbreeding level.However,C.chinensis carried significantly fewer deleterious mutations than C.kwechowensis-C. yunnanensis complex,as more effective purging selection reduced the accumulation of homozygous variants.We also detected signals of positive selection and adaptive introgression in different lineages,which facilitated the accumulation of favorable variants and formation of local adaptation.Hence,both types of selection and exogenous introgression could have mitigated inbreeding and facilitated survival and persistence of C.chinensis.Overall,our study provides critical insights into lineage differentiation,local adaptation,and the potential for future recovery of endangered trees.

不同上坡跑增速策略对男性业余马拉松跑者下肢关节运动学的影响

目的:探讨3种不同上坡跑增速策略的男性业余马拉松跑者在步速控制的条件下,下肢关节运动学及垂直地面反作用力的差异性。方法:根据排除和纳入标准,筛选18名业余马拉松运动员,并依据不同的上坡跑增速策略将其随机分为3组,定义G1组为步频增加组(n=6人),G2组为步长增加组(n=6人),G3组为步频步长同时增加组(n=6人),随后采用Vicon红外高速运动捕捉系统和ZebrisFDM-T系列步态分析跑台,分别采集受试者在6.6 km/h和10 km/h速度条件下的步态数据、下肢各关节运动角度及垂直地面反作用力峰值,并对其数据进行分析讨论。结果:最终有17人完成了整个实验。从6.6km/h增速到10km/h后,支撑腿着地瞬间,G2组的膝关节屈曲角度、踝关节背伸角度大于G1、G3组且均有显著增加,G1、G3组的膝关节屈曲角度、踝关节背伸角度均有一定程度的减小。支撑腿最大缓冲时,G2组3个关节的角度均出现了一定程度的增加,且G1、G3组的角度(除G3组髋关节屈曲角度)都有一定程度的减小。支撑腿蹬离瞬间,3组髋关节伸展角度都有一定程度的增加,G2组膝关节屈曲角度的减小幅度较G3组更为明显,G3组踝关节跖屈角度增加幅度较G1、G2组更大。结论:上坡跑过程中,增加步长和同时增加步长、步频的业余马拉松爱好者,对其膝关节及踝关节的功能需求较大,而步频的增加则对髋关节的功能较为依赖。选用增加步长或步频步长同时增加的增速策略,会带来下肢各关节更高的关节负荷。