Allele-specific expression and alternative splicing in horse×donkey and cattle×yak hybrids

Divergence of gene expression and alter native splicing is a crucial driving force in the evolution of species;to date, however the molecular mechanism remains unclear. Hybrids of closely related species provide a suitable model to analyze allele-specific expressi on (ASE) and allele-specific alter native splicing (ASS). Analysis of ASE and ASS can uncover the differences in cis-regulatory elements between closely related species, while eliminating interferenee of trans-regulatory elements. Here, we provide a detailed characterization of ASE and ASS from 19 and 10 transcriptome datasets across five tissues from reciprocal-cross hybrids of horsex don key (mule/hi nny) and cattlexyak (dzo), respectively. Results showed that 4.8%-8.7% and 10.8%-16.7% of genes exhibited ASE and ASS, respectively. Notably, IncRNAs and pseudogenes were more likely to show ASE than protein-coding genes. In addition, genes showing ASE and ASS in mule/hinny were found to be involved in the regulation of muscle strength, whereas those of dzo were involved in high-altitude adaptati on. In con clusi on, our study dem on strated that explorati on of genes showing ASE and ASS in hybrids of closely related species is feasible for species evolution research.

Influence of laser on arcs in alternate arcing during laser-twin-arc hybrid welding process

In this study, multi-information including spectrum, high-speed photograph and electrical signal was adopted to explore the coupling mechanism of alternate burning in laser-twin-arc welding process. Laser provides a conductive, stable plasma channel for arcs. Plasma radiation strengthened especially in the center of the arc after hybrid. High temperature plasma erupting from keyhole provides an upward reacting force which can prevent droplet from transfer. The charged particles consisted in high temperature plasma reduce the voltage that maintains arc ignition or burning. The results show that laser can influence the arc shape, prevent droplet transfer, reduce resistivity and stabilize arcs.

Investigation of Flux Regulation Performance and Experimental Validation of Novel Hybrid Excitation Brushless Claw-pole Alternators

针对电励磁爪极发电机效率低、永磁爪极发电机磁场调节困难等问题,提出一种新型的混合励磁无刷爪极发电机。介绍该电机的结构特点和磁场调节原理,采用三维有限元法对电机的空载磁场分布及磁场调节能力进行了分析,设计并制造了试验样机。样机试验结果验证了有限元分析的正确性,并表明在结构参数相同的情况下,与电励磁爪极发电机相比,新型混合励磁无刷爪极发电机具有气隙磁通密度高、功率密度高、低速输出性能好、励磁损耗低等特点。

不同灌溉模式对籼粳杂交稻甬优1540产量与水分利用效率的影响

旨在探讨不同灌溉模式对籼粳杂交稻甬优1540产量与水分利用效率的影响,并阐明其相关生理基础。本研究以甬优1540为材料,设置了3种灌溉模式,即长淹灌溉(continuous flooding,CF)、轻度干湿交替灌溉(alternate wetting and moderate drying, AWMD)以及重度干湿交替灌溉(alternate wetting and severe drying, AWSD)。研究结果表明,与CF相比, AWMD与AWSD均能显著提高水分利用效率,增幅分别为22.6%~25.6%与18.2%~23.1%;AWMD可以显著提高水稻产量,增幅为8.6%~10.0%,而AWSD则显著降低水稻产量,降幅为6.0%~7.5%。与CF相比, AWMD显著降低了拔节期水稻的茎蘖数、地上部干物质重、叶面积指数、移栽至齐穗期的光合势以及移栽至拔节期的作物生长速率,但显著提高了茎蘖成穗率、拔节至齐穗期的作物生长速率、主要生育期水稻根长密度、深根比、比根长、根系总吸收表面积与活跃吸收表面积,以及灌浆后2次土壤复水期的剑叶净光合速率、根系氧化力、根系与叶片中玉米素和玉米素核苷(Z+ZR)含量、籽粒中蔗糖-淀粉代谢途径关键酶活性等指标。以上结果表明, AWMD可以协同提高甬优1540产量与水分利用效率,优化根-冠生长发育特征,提高灌浆期植株生理活性,实现高产与水分高效利用,为本研究最佳水分管理模式。

含多类型直流的交直流混联电网潮流计算方法适用性分析

作为电网发展的新阶段,交直流混联电网呈现多类型直流参与、大规模交直流互联的特点,而关于统一迭代和交替迭代2种潮流计算方法的适用性尚未得到深入分析。为此基于含多类型直流的交直流混联电网对2种潮流计算方法的运算性能进行对比研究。推导了含常规直流、柔性直流、混合直流的交直流混联电网潮流模型,进而提出了相应的统一迭代法和交替迭代法。通过3个交直流混联电网测试系统和南方电网实际系统数据验证了潮流模型的有效性和潮流算法的准确性,结合系统负荷水平、系统强度、直流嵌入规模等因素对2种潮流计算方法的收敛性能和计算速度进行对比分析。研究结果表明,在含多类型直流的交直流混联电网中进行潮流计算时,统一迭代法的计算效率比交替迭代法高。

含能量路由器的交直流混合配电网潮流计算

能量路由器(energy router,ER)作为新兴电力电子设备,可以实现电能在电力系统中的灵活分配。分析ER对系统的影响,研究以ER为配电枢纽的交直流混合配电网潮流计算方法,对实现配电网的优化运行具有重要意义。文中首先基于改进交替迭代法建立ER的稳态潮流模型,并对ER直流端口采用下垂控制策略,结合传统解耦法,提出一种适用于含ER的配电网交直流解耦迭代潮流计算方法。以含有多个ER的IEEE 14节点和IEEE 69节点配电系统为算例进行仿真计算,验证所提方法的正确性与收敛性。为分析ER对系统运行的影响,对不同场景下IEEE 69节点测试系统进行仿真计算,证明ER在系统中可以支撑节点电压,减小系统运行损耗。

Hybrid Precoder and Combiner Design with Finite Resolution PSs for mmWave MIMO Systems

Hybrid precoding and combining have been considered as a promising technology, which can provide a compromise between hardware complexity and system performance in millimeter wave multiple-input multiple-output systems. However, most existing hybrid precoder and combiner designs generally assume that infinite resolution phase shifters(PSs) are used to produce the analog beamformers. In a practical scene, the design with accurate PSs can lead to high hardware cost and power consumption. In this paper, we investigate the hybrid precoder and combiner design with finite resolution PSs in millimeter wave systems. We employ alternate optimization as the main strategy to jointly design analog precoder and combiner. In addition, we propose a low complexity algorithm, where the analog beamformers are implemented only by finite resolution PSs to maximize spectral efficiency. Then, the digital precoder and combiner are designed based on the obtained analog beamformers to improve the spectral efficiency. Finally, simulation results and mathematical analysis show that the proposed algorithm with low-resolution PSs can achieve near-optimal performance and have low complexity.

The trajectory of hybrid and hydrogen technologies in North American heavy haul operations

The central aim of this paper is to provide an upto-date snapshot of hybrid and hydrogen technology-related developments and activities in the North American heavy haul railway setting,placed in the context of the transportation industry more broadly.An overview of relevant alternative propulsion technologies is provided,including a discussion of applicability to the transportation sector in general and heavy haul freight rail specifically.This is followed by a discussion of current developments and research in alternative and blended fuels,discussed again in both general and specific settings.Key factors and technical considerations for heavy haul applications are reviewed,followed by a discussion of non-technical and human factors that motivate a move toward clean energy in North American Heavy Haul systems.Finally,current project activities are described to provide a clear understanding of both the status and trajectory of hybrid and hydrogen technologies in the established context.

Hybrid Cartesian Grid Method for Moving Boundary Problems

A hybrid Cartesian structured grid method is proposed for solving moving boundary unsteady problems.The near body region is discretized by using the body-fitted structured grids,while the remaining computational domain is tessellated with the generated Cartesian grids.As the body moves,the structured grids move with the body and the outer boundaries of inside grids are used to generate new holes in the outside adaptive Cartesian grid to facilitate data communication.By using the alternating digital tree(ADT)algorithm,the computational time of hole-cutting and identification of donor cells can be reduced significantly.A compressible solver for unsteady flow problems is developed.A cell-centered,second-order accurate finite volume method is employed in spatial discretization and an implicit dual-time stepping low-upper symmetric Gauss-Seidel(LU-SGS)approach is employed in temporal discretization.Geometrybased adaptation is used during unsteady simulation time steps when boundary moves and the flow solution is interpolated from the old Cartesian grids to the new one with inverse distance weighting interpolation formula.Both laminar and turbulent unsteady cases are tested to demonstrate the accuracy and efficiency of the proposed method.Then,a 2-D store separation problem is simulated.The result shows that the hybrid Cartesian grid method can handle the unsteady flow problems involving large-scale moving boundaries.

A Study of Advanced Efficient Hybrid Electric Vehicles, Electric Propulsion and Energy Source

Recently global warming and the depletion of fuel resources have accelerated researchers’ efforts to produce more efficient and clean alternatives. This research presents a comprehensive review of the different adjustments/con figurations of electric vehicles (EVs) and hybrid electric vehicles (HEVs), traction motors for power systems, and wireless speed control of traction drive. Electronic installation of technology can reduce pollution efficiently and effectively. The efficient operation has always been one of the most common investigators’ objectives in the automotive industry and academic areas. There are several renewable energy resources for hybrid vehicles that will replace depleted gasoline worldwide. The purpose of this paper is the development of more efficient pure EVs, HEVs, and fuel cell electric vehicles (FCEV) present both a challenge and a definite solution to current mobility issues. Fuel consumption in cars is a concern due to the harmful effects on the environment. Among other battery sources, fuel cells (FC), super capacitors (SC), and photovoltaic cells are studied for vehicle application. A combination of these renewable energy sources can be used for hybrid electric vehicles (HEV) in the next generation of transportation. With the significant progress of automobile technology, the hybrid electric vehicle has already become the main achievement of transportation electrification due to its excellent fuel-saving performance.

基于蒙特卡罗模拟法的柔性交直流混联配电网概率潮流计算

随着高压直流输电和新能源并网技术的快速发展,电力系统运行工况愈加复杂多变。为更好评估现代电力系统的不确定性,文中研究了分布式发电中的风力发电和太阳能发电的随机出力对配电系统电压质量的影响,提出一种能够计及风光互补特性和换流站控制特性,基于蒙特卡罗模拟求解含有电压源换流器的交直流混联系统概率潮流计算方法。首先,针对换流站不同的控制方式,给出利用交替迭代法进行常规交直流潮流的计算模型。其次,建立了考虑风力发电、太阳能发电和负荷不确定性的概率潮流计算模型。最后,在修改后的IEEE-34节点系统上采用蒙特卡洛法计算节点电压、线路功率的均值和标准差。该方法能较为准确的反映新能源固有的不确定性及穿透率的影响,并有着良好的收敛性。

毫米波大规模MIMO系统混合连接天线结构的混合预编码算法研究

在大规模多输入多输出(Multiple Input Multiple Output,MIMO)系统中,混合连接天线结构结合全连接和部分连接的结构优势,能更好地平衡频谱效率和能量效率。但是当前该结构的混合预编码算法繁杂。针对这一问题,研究混合连接天线结构的低复杂度混合预编码算法设计。为了简化该结构的混合预编码算法,将信道矩阵划分成一系列子信道矩阵,分别对每一个子信道矩阵采用交替迭代矩阵分解(Alternating Iterative Matrix Decomposition,Alt-IMD)算法求解最优混合预编码矩阵。通过理论分析该算法复杂度,并且通过仿真实验分别对全连接天线结构、部分连接天线结构混合预编码算法、混合预编码算法的频谱效率和能量效率进行对比。结果表明:与当前混合预编码算法相比,该算法能获得更高的频谱效率和能量效率。

含LCC-MMC串/并联混合直流的交直流系统潮流计算方法

混合直流输电技术方案多样,直流系统拓扑结构复杂,目前的潮流算法面对复杂直流系统时建立数学模型存在困难,为此该文基于串联型、并联型混合交直流系统潮流计算进行研究。首先分析了白鹤滩、昆柳龙工程中混合直流系统的拓扑结构及稳态控制模式。然后根据换流站与单个换流器间状态变量的数值关系,对双极、多阀组换流站进行等效,导出了基于电网换相换流器(line commutated converter,LCC)和模块化多电平换流器(modular multilevel converter,MMC)的换流站潮流模型。在此基础上,通过分析换流站潮流模型间的内在联系,给出了串联型、并联型混合直流系统潮流模型建立方法,进而提出一种LCC-MMC串/并联混合交直流系统潮流交替迭代算法。最后,通过修改的IEEE 39节点串/并联交直流系统验证了所提模型及算法的有效性。

交错群图的混合故障诊断问题研究

为了衡量以交错群图为拓扑结构的多处理器系统在混合故障环境下的故障诊断能力,研究了交错群图在HPMC模型下的h-限制点诊断度和r-限制边诊断度。根据这2种混合故障诊断度的性质,得到了它们之间的关系。考虑到交错群图中相邻的顶点有公共邻点,将h和r划范围讨论。借助反证法,得到了交错群图在1≤h≤2n-7时的h-限制点诊断度是2n-h-4。然后由h-限制点诊断度和r-限制边诊断度的关系,确定了交错群图在3≤r≤2n-5时的r-限制边诊断度是2n-r-4。此外,通过构造相异的一致故障对并证明是不可区分的,确定了交错群图在h=2n-6,2n-5,2n-4时的h-限制点诊断度分别是1、0、0;在r=1,2时的r-限制边诊断度分别是2n-6、2n-7。这些结果显示出交错群图在混合故障环境下可自我识别故障元素的最大数值,体现了系统最大的故障诊断能力。

基于低频中压交流互联的网格化混合微电网结构及其关键装备

为了解决逐年增加的可再生能源发电与负荷分散集成导致的配电网功率倒灌以及电能质量问题,提出一种基于低频中压交流(low-frequency medium-voltage alternating current,LF-MVac)互联的网格化混合微电网结构,所提结构在能够实现潮流调控的基础上,还具备灵活组网能力及能更好地利用现有基础设施等优势。此外,设计了一种隔离型模块化多电平矩阵变换器(isolated modular multilevel matrix converter,I-M3C),给出了其拓扑与调制策略,建立了I-M3C平均电路模型,设计了基于双dq坐标变换的I-M3C控制策略,实现了中压交流(medium-voltage alternating current,MVac)、LF-MVac以及低压直流(low-voltage direct current,LVdc)3个端口之间的能量转换。最后,搭建了基于LF-MVac互联的网格化混合微电网仿真平台,证明了所提关键装备的有效性及相关理论分析的正确性。

基于目标分解的逐次迭代逼近混合预编码算法

为改善大规模毫米波多输入多输出的性能,提出一种基于目标分解的逐次迭代逼近混合预编码算法。基于目标分解,通过采用逐次迭代逼近、交替优化的求解方法和加入中继设备扩大传输范围的模型设计方法,研究混合预编码矩阵设计的问题。仿真结果表明,所提算法可以获得更加理想的系统均方误差和总和速率,其性能逼近理想预编码性能,具有有效性和可靠性。

High-performance photodetectors based on two-dimensional perovskite crystals with alternating interlayer cations

Organic-inorganic halide perovskite,as a low-cost,solution-processable material with remarkable optoelectronic properties,is ideal candidate to fabricate high-performance photodetectors and is expected to significantly reduce device costs.Compared to the common Dion-Jacobson and Ruddlesden-Popper two-dimensional(2D)layered hybrid perovskite compounds,the perovskites with alternating cations in the interlayer(ACI)phase show higher crystal symmetry and narrower optical bandgaps,which exhibit great potential for excellent photodetection performance.Herein,we report a high-performance photodetector based on the 2D bilayered hybrid lead halide perovskite single crystal with the ACI phase(GAMA_(2)Pb_(2)I_(7);GA=C(NH_(2))_(3)and MA=CH_(3)NH_(3)).The single-crystal photodetector exhibits high photoresponsivity of 1.56,2.54,and 2.60 A/W for incident light wavelengths of 405,532,and 635 nm under 9.82 nW,respectively,together with the correspondingly high detectivity values of 1.86×10^(12),3.04×10^(12),and 3.11×10^(12)Jones under the same operating conditions.Meanwhile,a high-resolution imaging sensor is built based on the GAMA_(2)Pb_(2)I_(7)single-crystal photodetector,confirming the high stability and photosensitivity of the imaging system.These results show that the 2D hybrid lead halide perovskites with alternating interlayer cations are promising for high-performance visible light photodetectors and imaging systems.

基于加权L^(1)-L^(2)拟合的模糊活动轮廓图像分割

为了对灰度不均匀图像进行分割,结合图像的局部和全局信息,提出基于加权L^(1)-L^(2)拟合能量项的模糊活动轮廓图像分割(fuzzy active contour based on weighted L^(1)-L^(2) fitting energy for image segmentation,FAWFE)模型。首先,利用模糊隶属度函数,基于图像局部和全局信息构建混合模糊拟合图像。然后,构建加权L 1拟合能量项,量化原始图像与混合模糊拟合图像之间的差异,有效地处理灰度不均匀问题。最后,结合L^(2)拟合能量项,保证能量泛函的凸性,使得模型解的存在性和唯一性得以保证,避免陷入局部极小。另外,采用交替迭代算法对FAWFE模型进行数值求解,并与经典的活动轮廓模型对比。结果表明,FAWFE模型不仅可以准确定位目标边界,而且可以在0.6 s左右实现对图像的处理,对于合成图像和真实图像均有良好的处理效果。

汽车发电机混合励磁转子性能及制造难点分析

混合励磁转子在生产过程中有较高的工艺要求,针对在制造过程中磁钢极性正确安装,流程检验中励磁线圈与集电环电励磁极性的判别,以及不同磁钢材料运用对性能提升的效果这3点作为切入点,通过磁钢与爪极的阵列配合,设计专用的检验设备在检验环节对励磁线圈进行通电校验,并使用不同材料磁钢进行发电机的性能试验。结果表明,配合励磁线圈正负极与磁钢组成海尔贝克阵列,能有效提升发电机输出功率,且汝铁硼材料相较于铁氧体对电性能的提升有更好的效果。