The low power and narrow speed range remain bottlenecks that constrain the application of small-scale wind energy harvesting.This paper proposes a simple,lowcost,and reliable method to address these critical issues.A ...The low power and narrow speed range remain bottlenecks that constrain the application of small-scale wind energy harvesting.This paper proposes a simple,lowcost,and reliable method to address these critical issues.A galloping energy harvester with the cooperative mode of vibration and collision(GEH-VC)is presented.A pair of curved boundaries attached with functional materials are introduced,which not only improve the performance of the vibration energy harvesting system,but also convert more mechanical energy into electrical energy during collision.The beam deforms and the piezoelectric energy harvester(PEH)generates electricity during the flow-induced vibration.In addition,the beam contacts and separates from the boundaries,and the triboelectric nanogenerator(TENG)generates electricity during the collision.In order to reduce the influence of the boundaries on the aerodynamic performance and the feasibility of increasing the working area of the TENG,a vertical structure is designed.When the wind speed is high,the curved boundaries maintain a stable amplitude of the vibration system and increase the frequency of the vibration system,thereby avoiding damage to the piezoelectric sheet and improving the electromechanical conversion efficiency,and the TENG works with the PEH to generate electricity.Since the boundaries can protect the PEH at high wind speeds,its stiffness can be designed to be low to start working at low wind speeds.The electromechanical coupling dynamic model is established according to the GEH-VC operating principle and is verified experimentally.The results show that the GEH-VC has a wide range of operating wind speeds,and the average power can be increased by 180%compared with the traditional galloping PEH.The GEH-VC prototype is demonstrated to power a commercial temperature sensor.This study provides a novel perspective on the design of hybrid electromechanical conversion mechanisms,that is,to combine and collaborate based on their respective characteristics.展开更多
Wireless sensor networks (WSNs) offer an attractive solution to many environmental, security and process monitoring. However, their lifetime remains very limited by battery capacity. Through the use of piezoelectric e...Wireless sensor networks (WSNs) offer an attractive solution to many environmental, security and process monitoring. However, their lifetime remains very limited by battery capacity. Through the use of piezoelectric energy harvesting techniques, ambient vibration can be captured and converted into usable electricity to create selfpowering WSN which is not limited by finite battery energy. This paper investigates analytically and experimentally the performance of a WSN powered by a Piezoelectric Energy Harvesting System (PEHS) and a material block-level modeling considering most key energy consumption of a wireless sensor node in a star topology network is proposed. By using real hardware parameters of existing components, the proposed model is used to evaluate the energetic budget of the node. The sensor node performance is evaluated regarding transmit packet size, duty cycle and the number of nodes that can be deployed. From the spectral properties of the available vibration inside two moving vehicles (automobile and train), the maximal recoverable power for each type of vehicle is estimated. Using a PEHS based on a cantilever beam optimized for low-frequency applications, 6 mW power is recovered in the case of the train while a 12.5 mW power is reached in the case of the automobile. It is observed that the sink may not operate with the recovered energy. However, the sensor node can sense and transmit data with a maximum size of 105.5 kbits when the duty cycle is 4 × 10<sup>-15</sup>. It is also achieved that the node is most effective when the measured physical phenomena vary slowly, such as the variations in temperature due to thermal inertia. Considering an optimized PEHS based on non-linear processing, it is shown that the sink can operate for 190% improvement of the recovered power.展开更多
With the rapid development of low-power communication technology and microelectronics technology, wearable and portable embedded health monitoring devices, micro-sensors, and human body network positioning devices hav...With the rapid development of low-power communication technology and microelectronics technology, wearable and portable embedded health monitoring devices, micro-sensors, and human body network positioning devices have begun to appear. For seeking reliable energy sources to replace battery on these devices, it is of great significance for developing low power products to explore the research of piezoelectric effect in conversion of human motion into electricity. Based on the different human motions, the existing technology of piezoelectric energy harvester (PEH) is firstly classified, including PEHs through heel-strike, knee-joint, arm motion, center of mass. The technology is then summarized and the direction of future development and efforts is further pointed out.展开更多
为了克服表面叉指电极d33模式微机电系统（MEMS）悬臂梁振动俘能器中存在的压电材料极化不完全、存在弯曲电场等问题,提出了一种电极贯穿于整个压电层的全d33模式MEMS悬臂梁振动俘能器。根据机电耦合模型,分析了电极尺寸与材料厚度对压...为了克服表面叉指电极d33模式微机电系统（MEMS）悬臂梁振动俘能器中存在的压电材料极化不完全、存在弯曲电场等问题,提出了一种电极贯穿于整个压电层的全d33模式MEMS悬臂梁振动俘能器。根据机电耦合模型,分析了电极尺寸与材料厚度对压电俘能器输出功率的影响。优化结果表明：当硅基底厚度为20μm、电极宽度1μm时,电极间距最优范围为25~75μm,PZT材料最优厚度为7μm,归一化后得到功率密度为34.5 m Wcm-3g-2n。通过在表面叉指电极d33模式俘能器的基础上增加电镀电极工艺,设计了不锈钢基底的全d33模式MEMS俘能器的工艺流程,完成了部分单元工艺。展开更多
针对嵌入秘密后灰度图失真明显的问题,提出一种基于像素值排序(PVO)的可逆信息隐藏算法。首先,将像素分成灰、白两层,选择灰层的像素作为目标像素,对目标像素十字交叉位置上的4个白色像素进行排序;然后根据排序结果计算两端两个像素的...针对嵌入秘密后灰度图失真明显的问题,提出一种基于像素值排序(PVO)的可逆信息隐藏算法。首先,将像素分成灰、白两层,选择灰层的像素作为目标像素,对目标像素十字交叉位置上的4个白色像素进行排序;然后根据排序结果计算两端两个像素的均值和中间两个像素的均值,利用可逆约束实现像素的动态预测;最后,根据预测结果构造预测误差直方图(PEH),使用环形复杂度实现秘密数据的自适应嵌入,并用同样的方法处理白色层像素。利用USC-SIPI标准图像库中6幅图像进行仿真实验,当嵌入容量(EC)为10 000 b,平均峰值信噪比(PSNR)为61.89 d B时,该算法能有效减小携密图像的失真。展开更多
基金the National Natural Science Foundation of China (Nos. 11802091and 12172127)the Hunan Province Science and Technology Innovation Program of China(Nos. 2020JJ3019 and 2019RS2044)the Scientific Researchof Hunan Provincial Department of Education of China (No. 21A0463)
文摘The low power and narrow speed range remain bottlenecks that constrain the application of small-scale wind energy harvesting.This paper proposes a simple,lowcost,and reliable method to address these critical issues.A galloping energy harvester with the cooperative mode of vibration and collision(GEH-VC)is presented.A pair of curved boundaries attached with functional materials are introduced,which not only improve the performance of the vibration energy harvesting system,but also convert more mechanical energy into electrical energy during collision.The beam deforms and the piezoelectric energy harvester(PEH)generates electricity during the flow-induced vibration.In addition,the beam contacts and separates from the boundaries,and the triboelectric nanogenerator(TENG)generates electricity during the collision.In order to reduce the influence of the boundaries on the aerodynamic performance and the feasibility of increasing the working area of the TENG,a vertical structure is designed.When the wind speed is high,the curved boundaries maintain a stable amplitude of the vibration system and increase the frequency of the vibration system,thereby avoiding damage to the piezoelectric sheet and improving the electromechanical conversion efficiency,and the TENG works with the PEH to generate electricity.Since the boundaries can protect the PEH at high wind speeds,its stiffness can be designed to be low to start working at low wind speeds.The electromechanical coupling dynamic model is established according to the GEH-VC operating principle and is verified experimentally.The results show that the GEH-VC has a wide range of operating wind speeds,and the average power can be increased by 180%compared with the traditional galloping PEH.The GEH-VC prototype is demonstrated to power a commercial temperature sensor.This study provides a novel perspective on the design of hybrid electromechanical conversion mechanisms,that is,to combine and collaborate based on their respective characteristics.
文摘Wireless sensor networks (WSNs) offer an attractive solution to many environmental, security and process monitoring. However, their lifetime remains very limited by battery capacity. Through the use of piezoelectric energy harvesting techniques, ambient vibration can be captured and converted into usable electricity to create selfpowering WSN which is not limited by finite battery energy. This paper investigates analytically and experimentally the performance of a WSN powered by a Piezoelectric Energy Harvesting System (PEHS) and a material block-level modeling considering most key energy consumption of a wireless sensor node in a star topology network is proposed. By using real hardware parameters of existing components, the proposed model is used to evaluate the energetic budget of the node. The sensor node performance is evaluated regarding transmit packet size, duty cycle and the number of nodes that can be deployed. From the spectral properties of the available vibration inside two moving vehicles (automobile and train), the maximal recoverable power for each type of vehicle is estimated. Using a PEHS based on a cantilever beam optimized for low-frequency applications, 6 mW power is recovered in the case of the train while a 12.5 mW power is reached in the case of the automobile. It is observed that the sink may not operate with the recovered energy. However, the sensor node can sense and transmit data with a maximum size of 105.5 kbits when the duty cycle is 4 × 10<sup>-15</sup>. It is also achieved that the node is most effective when the measured physical phenomena vary slowly, such as the variations in temperature due to thermal inertia. Considering an optimized PEHS based on non-linear processing, it is shown that the sink can operate for 190% improvement of the recovered power.
文摘With the rapid development of low-power communication technology and microelectronics technology, wearable and portable embedded health monitoring devices, micro-sensors, and human body network positioning devices have begun to appear. For seeking reliable energy sources to replace battery on these devices, it is of great significance for developing low power products to explore the research of piezoelectric effect in conversion of human motion into electricity. Based on the different human motions, the existing technology of piezoelectric energy harvester (PEH) is firstly classified, including PEHs through heel-strike, knee-joint, arm motion, center of mass. The technology is then summarized and the direction of future development and efforts is further pointed out.
文摘为了克服表面叉指电极d33模式微机电系统（MEMS）悬臂梁振动俘能器中存在的压电材料极化不完全、存在弯曲电场等问题,提出了一种电极贯穿于整个压电层的全d33模式MEMS悬臂梁振动俘能器。根据机电耦合模型,分析了电极尺寸与材料厚度对压电俘能器输出功率的影响。优化结果表明：当硅基底厚度为20μm、电极宽度1μm时,电极间距最优范围为25~75μm,PZT材料最优厚度为7μm,归一化后得到功率密度为34.5 m Wcm-3g-2n。通过在表面叉指电极d33模式俘能器的基础上增加电镀电极工艺,设计了不锈钢基底的全d33模式MEMS俘能器的工艺流程,完成了部分单元工艺。
文摘针对嵌入秘密后灰度图失真明显的问题,提出一种基于像素值排序(PVO)的可逆信息隐藏算法。首先,将像素分成灰、白两层,选择灰层的像素作为目标像素,对目标像素十字交叉位置上的4个白色像素进行排序;然后根据排序结果计算两端两个像素的均值和中间两个像素的均值,利用可逆约束实现像素的动态预测;最后,根据预测结果构造预测误差直方图(PEH),使用环形复杂度实现秘密数据的自适应嵌入,并用同样的方法处理白色层像素。利用USC-SIPI标准图像库中6幅图像进行仿真实验,当嵌入容量(EC)为10 000 b,平均峰值信噪比(PSNR)为61.89 d B时,该算法能有效减小携密图像的失真。
