Monolithic homogeneous integrated miniaturized triboelectric nanogenerator with an inner air cavity for energy harvesting

Science China Technological Sciences - To realize the high-efficiency acquisition of environmental mechanical energy, traditional triboelectric nanogenerators (TENGs) based on contact-separation...     

A triboelectric/electromagnetic hybrid generator for efficient wind energy collection and power supply for electronic devices

Harvesting energy from ambient environment has been considered as a promising strategy for driving portable electronic devices in a sustainable way. A wind driven triboelectric-electromagnetic hybrid nanogenerator has been fabricated to convert wind energy into electricity. It is composed of an electromagnetic generator(EMG) and a triboelectric nanogenerator(TENG) with the output power of 35 and 0.32 mW, respectively when the wind speed is 5 m/s. Generally, TENG shows a low current output with a high voltage output characteristic, on the contrary the EMG shows a high current output and a low voltage output. This hybrid nanogenerator overcomes these problems and exhibits comprehensive and efficient performance on scavenging energy.Moreover, in view of the output performance and charging ability of the hybrid nanogenerator, it shows high stability, making it suitable for charging capacitors or batteries and driving portable electronics sustainably. A new structure of integrated TENG and EMG was designed to harvest wind energy, which shows potential applications in portable and small device power supply system, especially in the areas of remote mountains, deserts, islands, etc., as emergency power supply.     

On high-performance rotational energy harvesting with a novel cam-like dielectric elastomer generator

Rotational energy is a type of common energy source that can be harvested for supplying low-powered electronic devices. This paper proposes and investigates a novel cam-like dielectric elastomer generator(CDEG) for high-performance rotational energy harvesting. A mushroom-head clamp is designed to form a type of advanced conical dielectric elastomer membranes(DEMs).Moreover, a type of multi-protrusion cam mechanism is designed in the CDEG to effectively convert any external rotational excitation...     

Coil-levitated hybrid generator for mechanical energy harvesting and wireless temperature and vibration monitoring

The development of wireless monitoring is currently restricted by the short lifetime of batteries,requiring frequent replacement.Utilization of abundant mechani...     

A numerical study of rock burst development and strain energy release

We consider rock burst to be a dynamic disaster similar to earthquakes, rapid land sliding, or coal mine gas dynamic disasters. Multi-scale mechanical principles imply the same mechanism of damage evolution proceeds the catastrophe. Damage may occur at various scales from a meso-scopic scale to a macroscopic, or engineering scale. Rock burst is a catastrophe at the scale of the engineering structure, such as a tunnel cross section or the work face of a long wall mine. It results from dynamic fracture of the structure where microscopic damage nucleates, expands, and finally propagates into a macroscopic sized fracture band. Rock burst must, therefore, undergo a relatively long development, or gestation, time before its final appearance. In this paper, a study of rock burst within a deeply buried tunnel by numerical methods is described. The results show that during rock burst gestation the distributed microscopic damage in the rock surrounding the tunnel localizes, intersects, and then evolves into a set of concentrated “V” shaped damage bands. These concentrated damage bands propagate in the direction of maximum shear as shearing slide bands take shape. Rock burst happens within the wedge separated by the shear bands from the native tunnel rock. An analysis of the wedge fracture shows that the unloading effects result in rock burst and rapid release of the strain energy. The implications for rock burst prediction in tunnels are that: (1) rock burst develops in the upper arch corners of in the tunnel cross section prior to developing in other zones, so good attention must be paid there; (2) all monitoring, prevention, and treatment of rock burst should be done during the gestation phase; (3) the shear bands contain abundant information concerning the physics and mechanics of the process and they are the foundation of physical and mechanical monitoring of acoustic emission, micro seismic events, stress, and the like. Thus a special study of the shearing mechanism is required.     

基于LabVIEW平台的虚拟正弦信号发生器的设计

虚拟仪器(Virtual Instrument,简称VI)是现代计算机软件技术、通信技术和测量技术相结合的产物.论述虚拟仪器的组成原理、主要功能、特点及应用,同时详细介绍基于LabVIEW虚拟仪器开发平台及设计虚拟正弦信号发生器的方法.     

A novel tuned heave plate system for heave motion suppression and energy harvesting on semi-submersible platforms

Deepwater offshore structures such as semi-submersible platforms suffer powerful ocean waves due to their location and site condition. The long distance away from the shore also brings many difficulties to energy supply for the platform operation. How to reduce the response of the platform and convert the wave energy into electrical power is a meaningful topic. In this paper, a tuned heave plate system (THP) is presented and designed to be employed on a semi-submersible platform for heave motion suppression and energy harvesting. This THP system is composed of spring supports, a power take-off system (PTO), and a heave plate. The PTO system is a permanent magnet linear generator (PMLG), which could directly convert the kinetic energy of the heave plate into electronic power. The stiffness of the spring supports is designed based on the principle of the tuned mass damper (TMD). The numerical model of the platform and the THP system is established according to the hydrodynamic analysis results of the platform. The model is tested and modified by scale model tests on the platform in the wave tank. A parameter study, including the size, tuned period, and damping ratio of the THP system, is conducted systematically based on the numerical model. The optimal parameters of the THP are selected due to the maximum heave motion reduction under severe wave conditions in South China Sea. The performance of the semi-submersible with and without the THP system under different wave conditions is analyzed. It is demonstrated that this novel tuned heave plate system could reduce the heave motion of the semi-submersible platform significantly and generate considerable power, which makes the THP system have a broad prospect for development.     

传统手作与当代设计的融汇

当代设计不断的从传统吸取养分和价值。如今,在设计领域,关于如何修复造物的人文内涵和生态价值、以及恢复人与造物之间的本质缔连,成为当代设计关注的重点和思考重心。提高对于民族文化的自觉意识在现代化浪潮的涌动的当今环境中变得尤为重要。     

直接接触式冰浆生成器参数分析及设计要点

为了提高冰浆生成器的传热性能,采用求偏导的方法对影响冰浆生成器性能的各参数进行理论分析.根据圆断面射流理论,得到换热效率与液柱高度的关系式,结果表明：当液柱高度为喷嘴直径的50倍时,换热效率≥0.9.进一步推导体积传热系数的公式,给出冰浆生成器的设计要点：冰浆生成器高度应为喷嘴直径的100倍,冰浆生成器直径应小于喷嘴直径的14倍以避免径向传热.最后对分析结果进行了实验验证,实验与理论分析结果一致：随着气体质量流量和气体比定压热容的增加以及气体进口温度的降低、制冰溶液体积的减少,体积传热系数增加.     

一种山楂采摘机的机构设计及其运动方程建立

为实现机械式采摘山楂,设计了一种五自由度的山楂采摘机构.首先设计出山楂采摘机构简图,然后利用D-H参数表示法对机构简图建立相应的运动学方程,最后通过Matlab软件拟合出相应图形验证了方程的正确性.     

环境WiFi能量采集系统的匹配网络与整流电路设计

设计了一款针对WiFi信号的环境能量采集系统,工作频率范围从2.4 GHz到2.485 GHz.该系统采用了4倍压整流电路,并设计了从天线到整流电路的宽带匹配电路,提升了能量采集的效率.设计的宽带匹配电路在WiFi工作频率范围内,S_(11)均小于-10 dB.整流电路可将采集信号增加4倍,能有效提高RF-DC转换效率.测试结果表明,所设计的电路达到了设计要求,在-10 dBm的输入功率下,达到了40%的RF-DC转换效率,并使超级电容在30 min内采集到了257 mV的电压.     

民间艺术与现代包装设计融合的思考

民间艺术融入现代包装设计有着积极的理论和现实意义.在分析民间艺术在包装设计中应用现状的基础上,提出了民间艺术与现代包装设计融合的路径,并提出了图形、造型、色彩、材质等方面的民间艺术在现代包装设计中的创新体现.     

一种北斗二号测距码生成器的设计

针对北斗二号卫星导航系统中普通测距码的生成问题,提出了一种改进的测距码生成的实现原理,并给出具体实现方案。与传统的测距码生成器相比,本设计采用不同卫星编码设置不同初值的方法,提高了电路使用的便利性,还在算法上采用并行处理的方法,提高了码生成速率。对电路功能的仿真证明其可以得到与传统码生成器相同的编码结果。     

Enhanced triboelectric output of PDMS-based composite film with bi-material filling and surface patterning

Triboelectric nanogenerators(TENGs) are highly promising energy-harvesting devices that exhibit considerable potential for use in self-powered wearable electronics. Nano/microfillers and surface microstructure modification have been proposed to improve the triboelectric performance of TENGs. In this work, performance-enhanced flexible polydimethylsiloxane(PDMS) was developed through bi-material(reduced graphene oxide/fluorinated ethylene propylene, rGO/FEP) modification and filtrationmembrane-pa...     

自供能转换器调理单元的等效建模与拓扑优化

自供能技术为智能电网中亟待解决的智能监测传感器的现场供电难题提供了一种有效解决方法。其中自供能转换器调理单元的优劣对自供能装置整体性能有重要影响。通过对自供能转换器典型调理单元进行建模和仿真分析,推导出典型调理电路平均功率表达式,分析了调理电路效率的影响因素和开关的控制策略。在此基础上提出了一种改进的调理单元拓扑结构,利用电感的续流作用改善调理电路的电压输出波形。推导并定义了影响因子β,从理论上证明了新拓扑结构的可行性。提出新电路元件参数选择原则,并据此原则设计仿真和实验电路。仿真和实验结果均表明:改进的调理单元拓扑可从输出波形等方面克服原有拓扑的缺点,提高自供能系统的工作效率。     

变速恒频双馈风力发电系统的速度模式控制

基于变速恒频双馈风力发电系统能实现最大风能追踪,首先建立了双馈感应发电机的三阶数学模型,在基于定子磁链定向的转子励磁控制策略基础上,提出在最大风能追踪的过程中,采用速度模式控制的系统动态特性优于采用电流模式控制的动态特性,并给出了状态空间解释.最后给出了仿真波形,仿真结果验证了分析的正确性.     

1 000 MW发电机变压器组保护容错设计和配置

1000MW发电机组电压等级高、容量大,其继电保护受到非常多的关注．提出大机组保护的配置方案以及可能面临的问题,分析保护的容错原理和技术,介绍失磁保护、定子接地保护及转子接地保护的选型要求,认为保护装置硬件系统的冗余度是确保1000MW机组安全经济运行的重要措施．     

一类带导数的数值积分公式

介绍一类带导数的数值积分公式，给出这类求积公式的推导过程、误差估计以及收敛性证明．利用这类求积公式在被积函数的导数容易计算，尤其是在积分区间的端点上的导数值容易计算，并且在不增加计算量或者少增加计算量的前提下达到提高计算精度的目的．计算实践证明，这类数值积分公式在一定条件下是行之有效的．     

基于塑性应变能的钢支撑疲劳损伤评估方法

在罕遇地震下,框架-中心支撑结构中的钢支撑常因局部屈曲位置的低周疲劳开裂而过早退出工作.在焊接工字形钢支撑低周疲劳试验研究基础上,提出了一种可用于框架-中心支撑体系非线性动力时程分析中钢支撑疲劳损伤评估的经验方法,并给出了相关步骤的算法流程.研究结果表明:以钢支撑滞回环塑性应变能为损伤参量,能实时估算在随机位移荷载下钢支撑的低周疲劳累积损伤发展,并与试验结果吻合较好.