Determination of Dynamic Load Condition of Aircraft Carrier based on Multivariable Distribution of Flight Parameters

In order to solve the design problem of dynamic load of a carrier-based aircraft,according to the relevant criteria of national military standards,eight key flight parameters of the dynamic load conditions for the aircraft carrier were selected.Based on the multivariable distribution data of landing flight parameters obtained from flight test,the distribution form and range limitation of each flight parameter were determined by using the probability distribution of each flight parameter and the spatial relationship among variables.Furthermore,100000 sets of data were constructed to simulate the landing condition of aircraft in the form of random number.After the envelope is screened by multivariable joint probability distribution,the boundary conditions were compared and merged,and finally the dynamic load conditions were obtained.In this paper,a set of dynamic load condition design method based on the aircraft requirements is constructed,which systematically covers all kinds of situations that occur in the process of aircraft landing,and improves the conventional design process of aircraft dynamic load.

Experimental Measurements of the Sensitivity of Fiber-optic Bragg Grating Sensors with a Soft Polymeric Coating under Mechanical Loading,Thermal and Magnetic under Cryogenic Conditions

The strain and temperature sensing performance of fiber-optic Bragg gratings （FBGs） with soft polymeric coating, which can be used to sense internal strain in superconducting coils, are evaluated under variable cryogenic field and magnetic field. The response to a temperature and strain change of coated-soft polymeric FBGs is tested by comparing with those of coated-metal FBGs. The results indicate that the coated-soft polymeric FBGs can freely detect temperature and thermal strain, their At variable magnetic field, the tested results indicate accuracy and repeatability are also discussed in detail. that the cross-coupling effects of FBGs with different matrixes are not negligible to measure electromagnetic strain during fast excitation. The present results are expected to be able to provide basis measurements on the strain of pulsed superconducting magnet/cable （cable- around-conduit conductors, cable-in-conduit conductors）, independently or utilized together with other strain measurement methods.

Empirical Thermal Investigation of Oil-Immersed Distribution Transformer under Various Loading Conditions

The distribution transformer is the mainstay of the power system.Its internal temperature study is desirable for its safe operation in the power system.The purpose of the present study is to determine direct comprehensive thermal distribution in the distribution transformers for different loading conditions.To achieve this goal,the temperature distribution in the oil,core,and windings are studied at each loading.An experimental study is performed with a 10/0.38 kV,10 kVA oil–immersed transformer equipped with forty–two PT100 sensors(PTs)for temperature measurement installed inside during its manufacturing process.All possible locations for the hottest spot temperature(HST)are considered that made by finite element analysis(FEA)simulation and losses calculations.A resistive load is made to achieve 80%to 120%loading of the test transformer for this experiment.Working temperature is measured in each part of the transformer at all provided loading conditions.It is observed that temperature varies with loading throughout the transformer,and a detailed map of temperature is obtained in the whole test transformer.From these results,the HST stays in the critical section of the primary winding at all loading conditions.This work is helpful to understand the complete internal temperature layout and the location of the HST in distribution transformers.

Computational Fracture Analysis of an AFM-Specimen under Mixed Mode Loading Conditions

Fracture processes in ship-building structures are in many cases of a 3-D character. A finite element （FE） model of an all fracture mode （AFM） specimen was built for the study of 3-D mixed mode crack fracture behavior including modes Ⅰ,Ⅱ, and Ⅲ. The stress intensity factors （SIFs） were calculated by the modified virtual crack closure integral （MVCCI） method, and the crack initiation angle assessment was based on a recently developed 3-D fracture criterion--the Richard criterion. It was shown that the FE model of the AFM-specimen is applicable for investigations under general mixed mode loading conditions, and the computational results of crack initiation angles are in agreement with some available experimental findings. Thus, the applicability of the FE model of the AFM-specimen for mixed mode loading conditions and the validity of the Richard criterion can be demonstrated.

Degradation of joint surface morphology, shear behavior and closure characteristics during cyclic loading

In order to investigate the failure mechanism of rock joint,a series of laboratory tests including cyclic direct shear tests under constant normal load(CNL)conditions were conducted.Morphology parameters of the rock joint surface were precisely calculated by means of a three-dimensional laser scanning machine.All test results were analyzed to investigate the shear behavior and normal displacement behavior of rock joints under CNL conditions.Degradation of rock joint surface during cyclic shear tests was also analyzed.The comparison results of the height parameters and the hybrid parameters of the joint surface during cyclic tests show that the degradation of the surface mostly happens in the first shear and the constant normal loads imposed on the joints have significant promotion effects on the morphology degradation.During cyclic shear tests,joints surfaces evolve from rough state to smooth state but keep an overall undulation.Dilatancy of rock joints degrades with the degradation of joint surface and the increase of normal loads.The closure deformation of joint is larger than that of the intact rock,and the normal stiffness increases with the increase of shearing times.

Effect of bolt inclination angle on shear behavior ofbolted joints under CNL and CNS conditions

Rock bolts are widely used in rock engineering projects to improve the shear capacity of the jointed rock mass.The bolt inclination angle with respect to the shear plane has a remarkable influence on the bolting performance.In this study,a new artificial molding method based on 3D scanning and printing technology was first proposed to prepare bolted joints with an inclined bolt.Then,the effects of the bolt inclination angle and boundary conditions on the shear behavior and failure characteristic of bolted joints were addressed by conducting direct shear tests under both CNL and CNS conditions.Results indicated that rock bolt could significantly improve the shear behavior of rock joints,especially in the post-yield deformation region.With the increase of bolt inclination angle,both the maximum shear stress and the maximum friction coefficient increased first and then decreased,while the maximum normal displacement decreased monotonously.Compared with CNL conditions,the maximum shear stress was larger,whereas the maximum normal displacement and friction coefficient were smaller under the CNS conditions.Furthermore,more asperity damage was observed under the CNS conditions due to the increased normal stress on the shear plane.

Optimal Scheduling of Air Conditioners for Energy Efficiency

Energy saving is one of the most important research hotspots, by which operational expenditure and CO2 emission can be reduced. Optimal cooling capacity scheduling in addition to temperature control can improve energy efficiency. The main contribution of this work is modeling the telecommunication building for the fabric cooling load to schedule the operation of air conditioners. The time series data of the fabric cooling load of the building envelope is taken by simulation by using Energy Plus, Building Control Virtual Test Bed （BCVTB）, and Matlab. This pre-computed data and other internal thermal loads are used for scheduling in air conditioners. Energy savings obtained for the whole year are about 4% to 6% by simulation and the field study, respectively.

基于傅里叶变换的多联机空调负荷提取及预测方法

多联机空调实际制冷量通常不等同于房间真实的空调负荷需求,导致基于数据驱动的负荷预测模型的预测效果往往较差。本文提出了一种基于傅里叶变换的从实际制冷量数据中提取空调真实负荷数据的方法。案例预测结果表明,该方法能够有效提取空调负荷数据,并能将基于人工神经网络的超短期空调负荷预测模型精度提升10.94%。

Behavior of transporting pipeline sections without and with hydrogen exposure based on full-scale tests

Pipeline transport of hydrogen is one of today’s economic and environmental challenges.In order to find safe and reliable application of both existing gas and build new pipelines,it is essential to carry out tests on full-scale pipeline section,including the potentially more dangerous places than the main pipe,the girth welds.For the investigations,pipeline sections of P355NH steel with girth welds were prepared and exposed to pure hydrogen at twice the maximum allowable operating pressure for 41 days.Subsequently,full-scale burst tests were carried out and specimens were cut and prepared from the typical locations of the failed pipeline sections for mechanical,and macro-and microstructural investigations.The results obtained were evaluated and compared with data from previous full-scale tests on pipeline sections without hydrogen exposure.The results showed differences in the behavior of pipeline sections loaded in different ways,with different characteristics of the materials and the welded joints,both in the cases without hydrogen exposure and in the cases exposed to hydrogen.

面向脉冲负载的基于超级电容储能UPQC设计及控制策略研究

针对带有脉冲负载电网的电压畸变和电流畸变问题,设计了带有超级电容储能的三电平统一电能质量调节器,提出了基于人工神经网络的方法对串联和并联补偿单元进行控制,基于双闭环PI控制的方法对超级电容储能单元进行控制。其中,串联补偿单元进行电压补偿,以维持负载电压的稳定,保证负载的用电需求;并联补偿单元进行电流补偿,以维持电源电流的稳定,避免电网受到持续大幅冲击;超级电容储能单元对直流侧进行充放电,以维持直流侧电压的恒定,保证串、并联侧的正常工作。所提方法省去了繁琐的坐标变换过程,避免了多个滤波器造成相位滞后的问题。仿真实验结果表明,所提拓扑和控制策略有助于改善带有脉冲负载电网的电能质量。

基于动态负荷的多联机能效测试方法研究与可行性探讨

本文研究了基于动态负荷的多联机能效测试方法及其可行性。传统的多联机能效测试标准主要基于稳态工况,无法全面反映系统在动态条件下的性能。基于动态负荷的测试方法通过模拟空调与实际建筑负荷的动态交互,能更真实地评估空调系统在真实环境中的动态响应能力和整体能效。本文探讨了将该测试方法应用于多联机系统的关键技术点,包括虚拟建筑模型的扩展以适应多区域负荷需求、多点控制和监测的实现、复杂负荷响应的模拟、系统启动和调节动态评估以及实验室设置的调整。基于动态负荷的多联机能效测试方法在技术上是可行的,但经济上需要较高的成本和资源投入。

面向新型电力负荷管理的混杂负荷集群协同管控

针对新型电力负荷管理中负荷协同控制问题,提出了面向新型电力负荷管理的混杂集群协同管控方法。以空调和电热水器混杂负荷集群为控制对象,分析了空调和电热水器负荷的物理和响应特性,分别建立了适用于空调和电热水器的聚合控制模型。基于空调和电热水器负荷的聚合响应特性,利用电热水器负荷和空调负荷响应特性上的优势和互补特性,构建了空调集群和电热水器集群的协同管控模型,控制大量负荷输出稳定响应。最后,设置不同的清洁能源发电场景,基于上述算法对清洁能源出力进行跟踪仿真,结果表明所提负荷集群协同算法在不同场景下的跟踪误差都控制在±0.04%之内,验证了该算法的有效性。

水蓄冷空调系统运行策略的分析

我国空调系统用电量占比越来越大,空调节能降耗成为建筑节能的重要研究方向。水蓄冷技术是空调节能的重要技术之一。介绍水蓄冷空调系统的特点和工作原理,提出基于复杂工况的建筑负荷预测和控制方法,实现蓄冷设备对能源的灵活消耗和存储。根据建筑空调在不同蓄冷率下的环控策略分析可知,通过合理优化运行策略,水蓄冷空调系统具有良好的投资经济性。

关于消防员电梯的几点思考

结合相关规范条文,针对电气设计人员对于消防员电梯井道照明、机房空调配电及五方通话等方面存在的疑惑或争议进行探讨,并提出笔者的见解。

一种基于储能型铁路功率调节器的再生制动能量控制策略研究

针对某长大坡道线路牵引负荷实测数据,首先分析了牵引负荷具有峰值功率高、波动性强、工况之间交替频繁且再生制动能量丰富的特点,并且基于储能型铁路功率调节器,提出一种再生制动能量控制策略。然后通过MATLAB/Simulink搭建仿真模型,根据仿真结果分析系统各工况下的能量转移特性,验证该能量控制策略的可行性,在储能系统削峰填谷的同时,对牵引供电系统出现的功率因数低、三相不平衡等电能质量问题也起到治理的效果,具有良好的应用前景和经济价值。

空调负荷运行特性研究及建模

空调负荷是近年来增长较快的一类负荷,其特性对电网的电压稳定性影响很大。该文在电力系统动态模拟实验室进行的空调特性试验的基础上,对空调负荷的静态特性、电压动态特性、启动过程和堵转过程进行了详细分析,建立了空调负荷的这4种重要运行状态的负荷模型,可作为空调负荷建模研究的重要参考。

单台空调负荷动态特性分析与建模

空调负荷的比例和影响日益增大，为分析其停机特性、启动特性以及电压扰动特性，选用一台辅助电热型分体落地式房间空调器进行实测。结果表明：0．6倍额定电压为空调的停机电压；空调启动时电流冲击倍数可达5～10倍，在0．3～0．5S之内平息；电压扰动过程中，当电压大于停机电压时有功功率变化小而无功功率变化大，当电压降到停机电压后空调停机且功率为0，当电压恢复到187V后再经过3～5s空调可重新启动，因此空调的电压扰动特性是分时段的。在此基础上对单台空调进行建模：电压高于停机电压时采用Karlsson-Hill模型，低于停机电压时空调停机，电压恢复时采用启动模型，可用一指数函数近似拟合功率振荡下降的包络线，结果表明该负荷模型可以很好地拟合空调的特性。

含有空调的综合电力负荷建模研究

随着经济的发展,空调负荷在负荷成分中已占有相当大的比重,并且对电网电压稳定有着不可忽略的负面影响。为了分析夏季含有大量空调区域的负荷特性,给出了含有空调的综合电力负荷建模的方法。对于其中的空调负荷比例这一重要参数,提出了一种基于地理分区,按照负荷节点类型计算空调负荷比例的实用化方法。通过单台空调实验,分别用纯电动机模型和电动机综合负荷模型辨识空调负荷参数,拟合其动态响应。结果表明,空调负荷在正常干扰时,不能够采用纯电动机模型描述,而应该采用综合电动机负荷模型描述。

空调群负荷动态特性分析与建模

为仿真分析空调群负荷的动态特性并建立其模型,在所建立的单台空调负荷模型的基础上,应用电力综合稳定分析程序(PSASP),对某变电站进行配电网扩展,分别接入全空调负荷和混合负荷(包括空调、感应电动机、恒阻抗)。当端电压大于临界电压时,空调群特性可由Karlsson-Hill模型反映;包含空调启动时,分别讨论假设空调群内空调同时启动、均匀启动以及正态分布随机启动3种情况。同时启动时,空调群启动部分沿用单台空调启动模型;均匀启动以及正态分布随机启动时,功率分段拟合。仿真结果表明:10kV母线上的冲击要明显大于0.4kV-3母线上的冲击;全空调负荷时的冲击要明显大于混合负荷时的冲击;空调群同时启动时的冲击最强,正态分布随机启动时次之,均匀启动时冲击最小。