利用植被覆盖度-地表温度特征空间提取厦门市土壤湿度信息

土壤湿度是水文学、气象学以及农业科学研究领域的一个重要参数。利用1989年和1996年两个时相Landsat TM遥感卫星影像来获取厦门的植被覆盖度和地表温度,并由此构建了植被覆盖度和地表温度组成的特征空间,最后利用该特征空间反演了土壤湿度,并分析湿度在两个时相中的变化情况。结果显示,在所研究的时间段内,厦门西南老城区的湿度得到增加。但是在东北部城市建成区扩展的地区,土壤湿度则明显降低。     

一种新型双向三电平倍流LCL-T谐振直流变换器

随着蓄能锂电池恒流充电方式的普及,针对双向车载充电机中传统电压源直流变换器不具备自然恒流输出问题,提出一种新型双向三电平倍流LCL-T谐振直流变换器,其由LCL-T谐振结合三电平级联中性点箝位有源桥构成。由于耦合变压器级联的特殊方式,有源桥各子桥臂可独立或并行工作,据此可设计不同的调制方式控制谐振腔输入电压,建立变换器一倍、二倍准恒流模式。为实现双向功率传输特性一致,谐振腔器件参数采用对称设计,进而研究了一种受归一化频率f_n、品质因数Q控制的LCL-T谐振准恒流输出,并考虑无功功率控制和实现开关管零电压开通,设计满足给定准恒流输出精度的输出工况筛选算法。最后通过所搭建的仿真平台和实验样机证明所提变换器在各模式下均能实现给定精度内的准恒流输出。     

考虑节点边际电价的配电网与多微电网双层鲁棒经济调度

可再生能源出力的不确定性给市场定价机制带来了挑战,实现市场参与者的利益均衡分配成为亟待解决的关键问题。提出一种计及风电出力不确定性的节点边际电价市场出清机制。建立配电网与多微电网协调优化调度的双层模型,上层模型为考虑风电出力及功率交互不确定性的配电网数据驱动鲁棒经济调度模型,下层模型为考虑电价型需求响应的微电网数据驱动鲁棒经济调度模型。通过配电网与微电网之间功率交互与电价信息的传递进行上、下层模型的迭代求解,实现不同市场参与者的利益均衡分配。测试系统的仿真结果验证了所提模型及求解方法的有效性。     

中压不接地配电网三相潮流新方法

在大量分布式电源接入中低压配电网的新形势下,三相潮流计算是分析其影响的基本手段。针对现有中压不接地配电网三相潮流研究主要采用人为设置参考中性点/零序电压的方式,导致无法仿真分析中性点/零序电压偏移、不接地网络零序潮流和相-地电压不平衡等情况,提出一种中压不接地配电网三相潮流新算法。首先,提出不接地配电网三相潮流在节点变量和导纳矩阵方面的特殊性。然后,设计基于功率平衡方程和牛拉法,采用导纳矩阵可逆化处理和矩阵替换技术实现约束零序电流为零的不接地配电网三相潮流算法。最后,基于6节点系统和修改的IEEE123算例仿真不接地配网的潮流,结合PSCAD验证所提方法在不同场景下的准确性以及在大电网中的适用性和收敛性,并在地市电网中进行实际应用。算例分析表明,所提算法计算结果准确,具有良好的工程实用性。     

基于多Agent系统的大型电网电压暂降评估

面向实际大型电网的暂降评估需要考虑覆盖全网特征的线路故障仿真,其仿真计算速度和稳定性是制约其实用化的主要因素。为此提出了一种基于多Agent系统的大型电网电压暂降评估方法。该方法根据仿真需求构造多Agent系统并制定协同交互规则。首先,由网架解析和故障设置Agent自主生成仿真任务。其次,由仿真管理和计算Agent动态执行海量仿真。最后,由数据处理和分析Agent异步存储仿真数据并生成评估结果。目前该方法已应用在某省级电网电压暂降评估工作中,取得了较好效果。实例证明所提方法加速比高,运行稳定,可为大型电网电压暂降评估实用化提供技术支撑。     

Surface Control and Electrical Tuning of MXene Electrode for Flexible Self-Powered Human–Machine Interaction

MXene materials emerge as promising candidates for energy harvesting and storage application. In this study, the effect of the surface chemistry on the work function of MXenes, which determines the performance of MXene-based triboelectric nanogenerator (TENG), is elucidated. First-principles calculations reveal that the surface functional group greatly influences MXene work function:  OH termination reduces the work function with respect to that of bare surface, while  F and  Cl increase it. Then, work functions are experimentally determined by Kelvin probe force microscopy. The MXene prepared by gentle etching at 40 °C for 48 h (GE_40/48) has the largest work function. Furthermore, an electron-cloud potential-well model is established to explain the mechanism of electron emission-dominated charge transfer and assemble a triboelectric device to verify experimentally its conclusions. It is found that GE_40/48 has the best performance with a 281 V open-circuit voltage, 9.7 µA short-current current, and storing 1.019 µC of charge, which is consistent with the model. Last, a patterned TENG is demonstrated for self-powered human–machine interaction application. This finding enhances the understanding of the inherent mechanism between the surface structure and the output performance of MXene-based TENG, which can be applied to other TENG based on 2D materials.     

In Situ Polymerizing Internal Encapsulation Strategy Enables Stable Perovskite Solar Cells toward Lead Leakage Suppression

Despite the outstanding power conversion efficiency (PCE) of perovskite solar cells (PSCs) achieved over the years, unsatisfactory stability and lead toxicity remain obstacles that limit their competitiveness and large-scale practical deployment. In this study, in situ polymerizing internal encapsulation (IPIE) is developed as a holistic approach to overcome these challenges. The uniform polymer internal package layer constructed by thermally triggered cross-linkable monomers not only solidifies the ionic perovskite crystalline by strong electron-withdrawing/donating chemical sites, but also acts as a water penetration and ion migration barrier to prolong shelf life under harsh environments. The optimized MAPbI₃ and FAPbI₃ devices with IPIE treatment yield impressive efficiencies of 22.29% and 24.12%, respectively, accompanied by remarkably enhanced environmental and mechanical stabilities. In addition, toxic water-soluble lead leakage is minimized by the synergetic effect of the physical encapsulation wall and chemical chelation conferred by the IPIE. Hence, this strategy provides a feasible route for preparing efficient, stable, and eco-friendly PSCs.     

Exploring a Stable and Dense 3D Lead Chloride Hybrid with Emission of Self-Trapped Excitons toward X-Ray Scintillation

The exceptional photophysical properties of 3D organic–inorganic lead halide hybrids (OILHs) endow their significant potential for usage in optoelectronics, which has sparked intense research on novel 3D OILHs and associated applications. However, constructing new 3D OILHs based on large organic cations suffers from tough challenges due to the limitation of the Goldschmidt tolerance factor rule, let alone further explorations of their practical applications. Herein, a brand-new 3D lead chloride hybrid, (1MPZ)Pb₄Cl₁₀·H₂O ( 1 , 1MPZ = 1-methylpiperazine) is reported, featuring a dense 3D lead chloride framework made of the corner-, edge-, and face-shared lead chloride polyhedra. 1 presents a broadband white light emission with a large Stokes shift and a nanosecond photoluminescence lifetime, which originates from radiative recombination of self-trapped excitons (STEs) induced by the highly distorted structure. Such a reabsorption-free and fast-decayed STEs emission coupling with the dense 3D architecture further enables 1 with effective X-ray scintillation with good sensitivity. Impressively, 1 also shows superior environmental and radiation stability. This study provides a new 3D OILH with appealing luminescence, not only expanding the 3D OILH family but also inspiring the exploitation of their optoelectronic applications.     

一种基于指数积的移动机械臂联合标定方法

提出一种基于指数积的移动机械臂联合标定方法,以实现移动平台和机械臂两者间位姿标定与机械臂运动学参数标定模型的统一.机械臂运动学参数标定使用最多的是基于D-H参数法,但D-H参数法无法克服相邻关节平行或接近平行时的奇异性问题,以及建模过程复杂、建模后的模型通用性差等问题.基于指数积的移动机械臂联合标定方法建模时不会因为关节轴平行而出现奇异性问题,建模过程简单.通过对整个系统的运动学方程进行微分运算,获得末端位姿误差和移动机械臂零位状态旋量误差及关节旋量误差的线性化模型.利用伴随矩阵方式建立关节旋量理论值与关节旋量实际值的关系,并通过改变伴随矩阵实现基于最小二乘法的参数辨识计算过程中参数更新.使用高精度激光跟踪仪作为测量工具,通过实验验证所提出方法的有效性.     

缓减电压暂降影响的电-气综合能源系统储气装置选址定容方法

针对电力系统故障导致的电压暂降通过电-气耦合设备对系统造成多次影响的问题,提出了一种缓减电压暂降影响的电-气综合能源系统储气装置选址定容方法。分析了电力系统发生电压暂降事件对电-气综合能源系统的影响;基于灵敏度分析提出了天然气系统储气装置选址方法;综合考虑投资成本与效益,以安装储气装置后效益的最大值为目标函数,确定储气装置最佳配置方案。通过对由IEEE 14节点电力系统和11节点天然气系统构成的电-气综合能源系统进行算例分析,验证了该缓减方法的正确性与有效性。