四连杆机构运动轨迹对液压支架整体性能的影响

通过对液压支架运动原理和受力工况的理论分析,论述了四连杆机构运动轨迹与液压支架整体性能的关系,并运用实例对比,具体分析不同四连杆运动轨迹的支架主要性能差异,综合分析四连杆机构运动轨迹对支架整体性能的影响。     

多用户无线供电通信网络中基于最大加权和速率的优化方案

针对多用户无线供电通信网络系统中的交叉耦合干扰问题,提出了一种基于时间反演技术联合优化上、下行时间分配和功率分配方案,以最大化上行加权和速率.利用时间反演特有的空时聚焦性抑制交叉耦合干扰;然后建立优化模型,将难以求解的加权和速率问题转化为最小均方误差问题;最后通过分级逐次优化变量,分别求出功率和时间的最优解.仿真结果表明,在引入时间反演技术抑制系统的交叉耦合干扰后,系统的平均加权和速率明显提升.     

A Shape‐Adaptive Thin‐Film‐Based Approach for 50% High‐Efficiency Energy Generation Through Micro‐Grating Sliding Electrification

Effectively harvesting ambient mechanical energy is the key for realizing self‐powered and autonomous electronics, which addresses limitations of batteries and thus has tremendous applications in sensor networks, wireless devices, and wearable/implantable electronics, etc. Here, a thin‐film‐based micro‐grating triboelectric nanogenerator (MG‐TENG) is developed for high‐efficiency power generation through conversion of mechanical energy. The shape‐adaptive MG‐TENG relies on sliding electrification between complementary micro‐sized arrays of linear grating, which offers a unique and straightforward solution in harnessing energy from relative sliding motion between surfaces. Operating at a sliding velocity of 10 m/s, a MG‐TENG of 60 cm² in overall area, 0.2 cm³ in volume and 0.6 g in weight can deliver an average output power of 3 W (power density of 50 mW cm^?2 and 15 W cm^?3) at an overall conversion efficiency of ～50%, making it a sufficient power supply to regular electronics, such as light bulbs. The scalable and cost‐effective MG‐TENG is practically applicable in not only harvesting various mechanical motions but also possibly power generation at a large scale.     

Self‐Powered Trace Memorization by Conjunction of Contact‐Electrification and Ferroelectricity

Triboelectric nanogenerator (TENG) is a newly invented technology that can effectively harvest ambient mechanical energy from various motions with promising applications in portable electronics, self‐powered sensor networks, etc. Here, by coupling TENG and a thin film of ferroelectric polymer, a new application is designed for TENG as a self‐powered memory system for recording a mechanical displacement/trace. The output voltage produced by the TENG during motion can polarize the dipole moments in the ferroelectric thin film. Later, by applying a displacement current measurement to detect the polarization density in the ferroelectric film, the motion information of the TENG can be directly read. The sliding TENG and the single‐electrode TENG matrix are both utilized for realizing the memorization of the motion trace in one‐dimensional and two‐dimensional space, respectively. Currently, the ferroelectric thin film with a size of 3.1 mm² can record a minimum area changing of 30 mm² and such resolution can still be possibly improved. These results prove that the ferroelectric polymer is an effective memory material to work together with TENG and thereby the fabricated memory system can potentially be used as a self‐powered displacement monitor.     

Self‐Recovering Triboelectric Nanogenerator as Active Multifunctional Sensors

A novel self‐recovering triboelectric nanogenerator (STENG) driven by airflow is designed as active multifunctional sensors. A spring is assembled into the STENG and enables the nanogenerator to have self‐recovering characteristic. The maximum output voltage and current of the STENG is about 251 V and 56 μA, respectively, corresponding to an output power of 3.1 mW. The STENG can act as an active multifunctional sensors that includes a humidity sensor, airflow rate sensor, and motion sensor. The STENG‐based humidity sensor has a wide detection range of 20%–100%, rapid response time of 18 ms, and recovery time of 80 ms. Besides, the STENG could be utilized in the application of security monitoring. This work expands practical applications of triboelectric nanogenerators as active sensors with advantages of simple fabrication and low cost.     

基于高能量转换效率的旋转式气动发动机动力学分析

针对目前常用气动发动机能量转换效率低的现状,提出一种新型旋转凸轮活塞式气动发动机结构。根据气动发动机工作原理,针对旋转式气动发动机膨胀容积大,缸内高压气体压力直接推动凸轮活塞旋转对外做功的结构特点,分析缸内气体压力与输出扭矩之间的关系,建立动力学模型,并以此动力学模型为基础,利用Matlab/Simulink软件对该发动机单缸工作过程进行计算机仿真分析。仿真结果表明:旋转式气动发动机具有低速时有效扭矩大,能量转换效率高的优点。     

空间不合成平板端射阵列副瓣研究

平板端射天线组阵不符合常规天线组阵规律,增益随着天线单元间距的增大而提高,在1.5倍波长时增益最高,但同时引入栅瓣问题.采用不均匀布阵抑制栅瓣,将阵元间距的稀疏约束从0.5λ栅格扩展到1.5λ栅格.经过大量仿真分析,发现当天线单元最小间距为1.5λ时,按常规不均匀阵列优化原理优化天线间距,可以抑制栅瓣但无法解决引入的高...