针对电力系统不对称负荷日益多样性的状况,将瞬时无功功率理论应用于提高功率因数和补偿三相不平衡的静止无功功率补偿装置(Static Var Compensator)控制之中,提出了一种基于新算法的SVC补偿控制方法。该算法以对称分量法为理论支撑,通...针对电力系统不对称负荷日益多样性的状况,将瞬时无功功率理论应用于提高功率因数和补偿三相不平衡的静止无功功率补偿装置(Static Var Compensator)控制之中,提出了一种基于新算法的SVC补偿控制方法。该算法以对称分量法为理论支撑,通过对负荷电流进行基波有功分量和无功分量的解耦,利用分离出的无功电流计算理想补偿导纳,简化了传统的不对称补偿算法。采用Matlab/Simulink对所提出的控制算法进行仿真建模,建立对晶闸管相控电抗器(TCR)并联电容型SVC的控制,仿真结果证明了所提方法的正确性和可行性。展开更多
While hallmarks of rodent spermatogonia stem cell biomarkers' heterogeneity have recently been identified, their stage and subset distributions remain unclear. Furthermore, it is currently difficult to accurately ...While hallmarks of rodent spermatogonia stem cell biomarkers' heterogeneity have recently been identified, their stage and subset distributions remain unclear. Furthermore, it is currently difficult to accurately identify subset-specific SSC marker distributions due to the poor nuclear morphological characteristics associated with fixation in 4% paraformaldehyde. In the present study, testicular cross-sections and whole-mount samples were Bouin fixed to optimize nuclear resolution and visualized by immunohistochemistry (IHC) and immunofluorescence (IF). The results identified an expression pattern of PLZFhighc-KITpos in A1 spermatogonia, while A2–A4-differentiating spermatogonia were PLZFlowc-KITpos. Additionally, this procedure was used to examine asymmetrically expressing GFRA1 and PLZF clones, asymmetric Apr and false clones were distinguished based on the presence or absence of TEX14, a molecular maker of intercellular bridges, despite having identical nuclear morphology and intercellular distances that were <25 μm. In conclusion, this optimized Bouin fixation procedure facilitates the accurate identification of spermatogonium subsets based on their molecular profiles and is capable of distinguishing asymmetric and false clones. Therefore, the findings presented herein will facilitate further morphological and functional analysis studies and provide further insight into spermatogonium subtypes.展开更多
Pentamaran,a vessel with five hulls,can be an alternative for high-speed vessels due to its advantages,for instance,its excellent stability and seakeeping performance and broader deck space than an equivalent monohull...Pentamaran,a vessel with five hulls,can be an alternative for high-speed vessels due to its advantages,for instance,its excellent stability and seakeeping performance and broader deck space than an equivalent monohull with the same displacement.The destructive interference between the system of waves produced by the vessel’s hulls might benefit the reduction of power consumption.This study investigated a Wigley hull form pentamaran model with five asymmetric and symmetric hull config-urations and three variations of hull separation.The ship model was towed in conditions of fixed towing and calm water with Froude numbers(Fr)ranging from 0.55 to 1.00.A resistance analysis had been carried out to ensure proper comparison between the asymmetric and symmetric hull configurations.Results showed that total resistance coefficient of the asymmetries created different properties from the symmetries,that is,symmetries produced steadier trends than asymmetries.The hull separation variation caused a slight alteration in the total resistant coefficient(in magnitude)under the same configuration.Although not a single configuration outperformed the others in the entire range of Fr,three configurations were noteworthy as optimum models based on their Fr range.Moreover,a configuration of asymmetric hull with S/L=0.22 could generate a constant destructive interference throughout the investigated Fr range.展开更多
Mass transfer characteristics have been investigated in a 113 mm diameter asymmetric rotating disk contactor of the pilot plant scale for two different liquid–liquid systems. The effects of operating parameters inclu...Mass transfer characteristics have been investigated in a 113 mm diameter asymmetric rotating disk contactor of the pilot plant scale for two different liquid–liquid systems. The effects of operating parameters including rotor speed and continuous and dispersed phase velocities on the volumetric overall mass transfer coefficients are investigated. The results show that the mass transfer performance is strongly dependent on agitation rate and interfacial tension, but only slightly dependent on phase flow rates. In this study, effective diffusivity is used instead of molecular diffusivity in the Grober equation for estimation of dispersed phase overall mass transfer coefficient.The enhancement factor is determined experimentally and there from an empirical expression is derived for prediction of the enhancement factor as a function of Reynolds number. The predicted results compared to the experimental data show that the proposed correlation can efficiently predict the overall mass transfer coefficients in asymmetric rotating disk contactors.展开更多
文摘针对电力系统不对称负荷日益多样性的状况,将瞬时无功功率理论应用于提高功率因数和补偿三相不平衡的静止无功功率补偿装置(Static Var Compensator)控制之中,提出了一种基于新算法的SVC补偿控制方法。该算法以对称分量法为理论支撑,通过对负荷电流进行基波有功分量和无功分量的解耦,利用分离出的无功电流计算理想补偿导纳,简化了传统的不对称补偿算法。采用Matlab/Simulink对所提出的控制算法进行仿真建模,建立对晶闸管相控电抗器(TCR)并联电容型SVC的控制,仿真结果证明了所提方法的正确性和可行性。
基金the grants from the National Key Research and Development Program of China (Project No. 2016YFC1000200)the National Natural Science Foundation of China (Project No. 31472054).
文摘While hallmarks of rodent spermatogonia stem cell biomarkers' heterogeneity have recently been identified, their stage and subset distributions remain unclear. Furthermore, it is currently difficult to accurately identify subset-specific SSC marker distributions due to the poor nuclear morphological characteristics associated with fixation in 4% paraformaldehyde. In the present study, testicular cross-sections and whole-mount samples were Bouin fixed to optimize nuclear resolution and visualized by immunohistochemistry (IHC) and immunofluorescence (IF). The results identified an expression pattern of PLZFhighc-KITpos in A1 spermatogonia, while A2–A4-differentiating spermatogonia were PLZFlowc-KITpos. Additionally, this procedure was used to examine asymmetrically expressing GFRA1 and PLZF clones, asymmetric Apr and false clones were distinguished based on the presence or absence of TEX14, a molecular maker of intercellular bridges, despite having identical nuclear morphology and intercellular distances that were <25 μm. In conclusion, this optimized Bouin fixation procedure facilitates the accurate identification of spermatogonium subsets based on their molecular profiles and is capable of distinguishing asymmetric and false clones. Therefore, the findings presented herein will facilitate further morphological and functional analysis studies and provide further insight into spermatogonium subtypes.
文摘为了满足下一代无线通信的需求,基于最近提出的非对称毫米波大规模多输入多输出(multipleinput multiple-output,MIMO)系统架构,研究了非对称毫米波大规模MIMO系统信道特性——信道非对称性.根据非对称毫米波大规模MIMO系统架构和影响毫米波信道非对称性的主要因素,提出了刻画上下行信道非对称性的新参数——非对称因子.同时利用实验室自行研发的射线跟踪平台对非对称毫米波信道进行仿真分析.结果表明,基站收发天线阵列配置不同是导致信道非对称性的根本原因,复杂的传播环境使得这种非对称性更加突出,严重情况下室内场景非对称因子可达到-30 dB左右.同时室外视距(line-of-sight,LoS)和非视距(non-line-ofsight,NLoS)场景下的非对称因子累积分布函数(cumulative distribution function,CDF)与高斯分布拟合程度较好,而NLoS场景下明显比LoS场景下的非对称因子小.因此,非对称因子能够直观地描述出不同场景中上下行信道的非对称程度,而且非对称毫米波大规模MIMO系统也应以场景为导向进行信道特性分析.
基金financially supported by the Hibah Q1Q2:NKB-0329/UN2.R3.1/HKp.05.00/2019
文摘Pentamaran,a vessel with five hulls,can be an alternative for high-speed vessels due to its advantages,for instance,its excellent stability and seakeeping performance and broader deck space than an equivalent monohull with the same displacement.The destructive interference between the system of waves produced by the vessel’s hulls might benefit the reduction of power consumption.This study investigated a Wigley hull form pentamaran model with five asymmetric and symmetric hull config-urations and three variations of hull separation.The ship model was towed in conditions of fixed towing and calm water with Froude numbers(Fr)ranging from 0.55 to 1.00.A resistance analysis had been carried out to ensure proper comparison between the asymmetric and symmetric hull configurations.Results showed that total resistance coefficient of the asymmetries created different properties from the symmetries,that is,symmetries produced steadier trends than asymmetries.The hull separation variation caused a slight alteration in the total resistant coefficient(in magnitude)under the same configuration.Although not a single configuration outperformed the others in the entire range of Fr,three configurations were noteworthy as optimum models based on their Fr range.Moreover,a configuration of asymmetric hull with S/L=0.22 could generate a constant destructive interference throughout the investigated Fr range.
文摘Mass transfer characteristics have been investigated in a 113 mm diameter asymmetric rotating disk contactor of the pilot plant scale for two different liquid–liquid systems. The effects of operating parameters including rotor speed and continuous and dispersed phase velocities on the volumetric overall mass transfer coefficients are investigated. The results show that the mass transfer performance is strongly dependent on agitation rate and interfacial tension, but only slightly dependent on phase flow rates. In this study, effective diffusivity is used instead of molecular diffusivity in the Grober equation for estimation of dispersed phase overall mass transfer coefficient.The enhancement factor is determined experimentally and there from an empirical expression is derived for prediction of the enhancement factor as a function of Reynolds number. The predicted results compared to the experimental data show that the proposed correlation can efficiently predict the overall mass transfer coefficients in asymmetric rotating disk contactors.
