An electromagnetic, vibration-powered generator for intelligent sensor systems

This paper describes the design of miniature generators capable of converting ambient vibration energy into electrical energy for use in powering intelligent sensor systems. Such a device acts as the power supply of a microsystem which can be used in inaccessible areas where wires can not be practically attached to provide power or transmit sensor data. Two prototypes of miniature generator are described and experimental results presented. Prototype A is based around two magnets coupled to a coil attached to a cantilever; prototype B is based around four magnets.

For prototype A, experimental results are given for its resonant frequency and its open circuit and loaded output as a function of vibration amplitude. For prototype B, experimental results are given for the generator’s Q factor in air and vacuum, its output voltage as a function of vibration amplitude as well as its magnetic field strength. This generator has been tested on a car engine and shown to produce a peak power of 3.9 mW with an average power of 157 μW.     

一种振动自供能无线传感器的电源管理电路

针对振动能量采集器的输出功率过低不足以直接驱动无线传感器的问题,设计了振动自供能无线传感器的电源管理电路,根据调谐和阻抗变换原理对能量采集器进行了阻抗匹配,以最大功率对储能超级电容进行充电,对能量存储和电源管理电路的充放电特性进行了理论分析和实验验证。结果表明,该电路大幅度提高了采集器的输出功率和对储能超级电容充电的效率,当0.47 F超级电容电压达到0.6 V时,能量瞬间释放电路控制超级电容瞬间放电,成功驱动最大功耗为75 mW的无线传感器工作。     

Reconfigurable H‐plane waveguide phase shifters prototyping with additive manufacturing at K‐band

This work presents the design and manufacturing of a K‐band reconfigurable phase shifter completely implemented in waveguide technology for reduced insertion loss, good matching, and large phase shifting range. The device is based on the combination of a short slot coupler and two tunable reactive loads implemented as a section of short‐circuited waveguide where an adjustable metallic post is inserted. Three prototypes of this design have been manufactured using different techniques (conventional computer numerical control machining, a low‐cost fused filament fabrication technique and direct metal laser sintering) in order to assess its performance for different applications. The prototypes have been characterized experimentally and the achieved results are evaluated and compared. The proposed phase shifter, since it is fully developed in waveguide technology, eliminates the need of adding transitions to planar structures in order to integrate lumped components like pin diodes or varactors. Therefore, this device has a great potential in high‐power beam steering phased arrays.     

快速原型虚拟逼真设计原理及体系结构

在分析设计的特点和发展趋势的基础上,提出快速原型虚拟逼真设计,并对其特点和原理进行了讨论,快速原型虚拟逼真设计是面向并行工具,基于虚拟原型和虚拟环境仿真的设计,强调虚拟原型的快速生成和演化,在关键技术,原型系统以及开发环境三个层次上论述了快速原型虚拟逼真设计的研究,提出快速原型虚拟逼真设计模型以及基于该模型的体系结构。     

User-interface design for text editing: A case study

This paper describes the design of the user interface of a text editor named Occam with the goal of communicating by example the process of user-interface design. An attempt is made to induce principles; where that attempt falls, the raw details are presented. First Occam Itself Is described, and then aspects of its user Interface are used to exemplify (1) power versus ease of learning, (2) the use of prototypes and user feedback, (3) the importance of planning and (4) error detection and handling.     

基于汉字原型的手写汉字识别

本文以现存三种汉字的计算机表示和两种传统的汉字结构分析方法进行评述，应用拓扑和几何的基本原理，分析了汉字结构及其制约关系，确定了四类组成汉字的基本关系，在此基础上实现了汉字原型，最后给出了汉字原型应用手写汉字识别的实例。     

Externally resonated linear microvibromotor for microassembly

A new method for on-substrate fine positioning of microscale/mesoscale discrete components is presented, where component positions are finely adjusted using microlinear sliders and fixtures on the substrate. Each microlinear slider is actuated by vibratory impacts exerted by two pairs of microcantilever impacters. These microcantilever impacters are selectively resonated by shaking the entire substrate with a piezoelectric vibrator, requiring no need for built-in driving mechanisms such as electrostatic comb actuators, as reported previously. This selective resonance of the microcantilever impacters via an external vibration energy field provides with a very simple means of controlling forward and backward motion of the microlinear slider, facilitating assembly and disassembly of a microcomponent on a substrate. An analytical model of the device is derived in order to obtain, through the simulated annealing algorithm, an optimal design, which maximizes translation speed of the linear slider at desired external input frequencies. Prototypes of the externally resonated linear microvibromotor are fabricated using the three-layer polysilicon surface micromachining process provided by the Microelectronics Center of North Carolina, Research Triangle Park, NC, multiuser microelectromechanical processes service. These prototypes are tested for forward and backward motion via external vibration applied by an piezoelectric flexure vibrator, as well as the horizontal positioning and release of 500-μm-square polysilicon chips against a reference fixture element anchored to the substrate     

Part precision improvement in incremental sheet forming of not axisymmetric parts using an artificial cognitive system

Incremental sheet forming is a flexible process that uses a hemispherical tool moved by a CNC machine to form a blank sheet. It is adopted in the production of prototypes, small series or customized parts since it is characterized by low costs and higher process times with respect to traditional forming technologies. One of its main lacks is represented by the low geometrical accuracy, therefore solutions for errors reduction or compensation are required to improve the process. In this paper, an iterative algorithm based on an artificial cognitive system is presented and validated on a not axisymmetric part adopting different tool paths and materials. The results show that the integration of the proposed algorithm with the ISF manufacturing system allows to improve its intelligence and to achieve a geometrical precision similar to the traditional forming processes.     

Power supply sources based on resonant energy harvesting

The paper presents two example approaches to energy harvesting. Mechanical energy harvesting system is based on vibrational minigenerator. Basic relations of its analytical model are given in order to obtain an idea about the operating conditions. Electromagnetic harvesting system is based on tuned resonant nano-structure. Its concept allows impedance matching in order to operate in given frequency range. The matching properties are verified by means of numerical finite element analysis. For power management of vibration energy harvesting system several circuit design concepts are presented together with simulation results and basic properties comparison.     

A multi-prototype clustering algorithm

Clustering is an important unsupervised learning technique widely used to discover the inherent structure of a given data set. Some existing clustering algorithms uses single prototype to represent each cluster, which may not adequately model the clusters of arbitrary shape and size and hence limit the clustering performance on complex data structure. This paper proposes a clustering algorithm to represent one cluster by multiple prototypes. The squared-error clustering is used to produce a number of prototypes to locate the regions of high density because of its low computational cost and yet good performance. A separation measure is proposed to evaluate how well two prototypes are separated. Multiple prototypes with small separations are grouped into a given number of clusters in the agglomerative method. New prototypes are iteratively added to improve the poor cluster separations. As a result, the proposed algorithm can discover the clusters of complex structure with robustness to initial settings. Experimental results on both synthetic and real data sets demonstrate the effectiveness of the proposed clustering algorithm.     

A compact planar distributed tactile display and effects of frequency on texture judgment

This paper describes the development of a planar distributed tactile display and the evaluation of the results of its effectiveness for displaying textures. The tactile display is composed of a 6 × 5 pin array actuated by 30 piezoelectric bimorphs. The distance between each pin's centers is 1.8 mm. Vertical excursion of each pin is controlled over a 0–0.7 mm range. Perceptual experiments were conducted to evaluate the performance of the system under three conditions: active touch, passive touch with vibration and passive touch without vibration. The experimental results showed that vibrational stimuli helped subjects discriminate tactile patterns. Measurements of the error rate during discrimination tasks were used to find an optimal vibration frequency for stimuli presented at a constant sensation level (32 SLdB above threshold). The experiment was repeated, this time holding the energy transferred mechanically to the fingertip tissue constant. At low frequencies, we found that the passive stimulation allowed subjects to discriminate just as well as active touch of static stimuli did. The results suggested new possibilities for displaying texture using passive touch, constant energy and spatially varied vibration frequency.     

汽轮机组振动信号的测量与分析

针对目前汽轮机组振动的特点,将振动信号分为两类,即轴振（相对振动）和瓦振（绝对振动）。首先分析了汽轮机组的振动概况及其对机组的影响;然后分别介绍了机组振动的测量和分析方法。具体地从传感器谈起,解释了机组的轴振和瓦振的不同测量原理。针对振动的三要素即振幅、频率及相位分别做了介绍;最后以300MW机组为例,说明其振动测点的一般布置。     

Development of miniaturized piezoelectric actuators for opticalapplications realized using LIGA technology

To combine the advantages of the LIGA technology and piezoelectric materials, first prototypes of movable elastic LIGA structures have been realized on piezoelectric substrates. The structures consist of a flexible beam fixed to the piezoelectric substrate at its two ends in order to amplify the d₃₁-contraction of the piezoelectric substrate. By using this flexible LIGA beam as a magnification mechanism, the small displacements of the piezoelectric substrate are amplified by more than a factor of 20, offering various possibilities of applications, especially in micro-optics. In this paper, first the fabrication process and the performance of these new prototypes of LIGA piezoelectric actuators are described in detail, demonstrating the feasibility of the new concept combining the LIGA technique and piezoelectric substrates. Subsequently, LIGA-piezoelectric actuators developed for micro-optical applications are presented. These new optical actuators are also based on an elastic beam but slightly modified in order to modulate light propagating in optical fibers. They find promising applications as micro-optical attenuators or choppers whose performance is demonstrated     

Snap-Action Bistable Micromechanisms Actuated by Nonlinear Resonance

This paper presents analysis, design, realization, and experimental demonstration of a bistable switch actuated dynamically utilizing mechanical resonance phenomenon. We demonstrated that if a bistable structure is driven into a resonance near one of its states, it may achieve a large enough amplitude of vibration, sufficient to switch between its stable states. Using energy analysis, we concluded that dynamic switching of bistable structures may provide significant energy advantages over conventional static-switching approaches. To confirm the results, we derived analytically the closed-form actuation conditions guaranteeing switching between the states of a bistable structure and applied these conditions to experimental devices. Micromachined prototypes of dynamically actuated bistable switches were designed, fabricated, and characterized. We demonstrated experimentally that resonant dynamic switching provides energy saving of around 60% at atmospheric pressure with proportional increase in efficiency as the pressure decreases.     

Model-based design and test of vibration energy harvester for aircraft application

This paper deals with a development process of a vibration energy harvesting device in aircraft applications. The vibration energy harvester uses ambient energy of mechanical vibration and it provides an autonomous source of energy for wireless sensors or autonomous applications. This application presents a complex engineering problem and the vibration energy harvester consists of precise mechanical part, electro-mechanical converter, electronics and a powered application. It can be perceive as a mechatronic system and a mechatronic approach was used for development of our vibration energy harvester. An essential step of development process is simulation modeling which is based on mechatronic approach. Presented model-based design of vibration energy harvester is very useful during development process and the whole development process of the autonomous energy source is presented in this paper. The main aim of the paper is an introduction of our development methodology and our approach is presented on a sample of the vibration energy harvester for aircraft applications under project ESPOSA.     

压电式双振子微型发电机功率调节电路设计

为克服压电式单振子微型发电机通过一般整流、滤波和储能控制电路不能连续为瞬时发射功率较大的无线传感器网络发射模块供电的问题,提出了一种双振子振动发电的结构思想,介绍了双振子振动发电原理;提出了一种双振子微型发电机输出功率调节控制电路技术方案,它由主一辅整流电路、主储能器、滤波器、辅助补充能量控制电路、稳压电路、滞回比较器、开关控制电路和电子开关等组成.经实验证明:封装了该功率调节电路的压电式双振子微型发电机平均输出功率为250～950 μw,瞬时输出功率可以达到680 mw,而自身的功耗只有40微瓦以下,能满足连续振动环境中微功耗电子器件、传感器或间歇式较大功耗遥测电路供电的要求.     

Structural improvement for solder joint failure in ultrasonic plastic assembly

This paper presents a method of structural dynamic analysis with finite element method to identify the cause failure of solder joint caused by the vibration of ultrasonic welding. In this method, explicit FE method and its contact algorithm are used to simulate the energy transmission from vibrational energy to internal energy under some assumptions. Therefore, firstly, its feasibility is verified by 2D coupled thermal–mechanical analysis. Then, based on a certain type of cell phone battery, a 3D FE model is established for analyzing the vibration of the solder joints during ultrasonic welding. According to the simulation, we analyze the cause of the failure from three aspects: the location of the chip, the shape of the PCB and the structure of the housing. Correspondingly, the improvements are presented and applied to trial manufacture. The result from mass production shows that the improvements can decrease the reject ratio by 90% compared with the original design.     

An expert system for hydro/aero-static spindle design used in ultra precision machine tool

A novel expert hydro/aero-static spindle design system strategy is presented in this paper. It is based on the comprehensive principles of machine design, machining dynamics and metal cutting mechanics. The transmission and lubrication types of the spindle are decided by a selection system, which utilize a dedicated logical choice algorithm in the light of the specifications of both workpiece material and desired cutting condition. Hydro/aero-static spindles are designed by this system from its dynamics perspective. The chatter vibration of the spindle is automatically improved by optimizing the structural parameters of the spindle. Meanwhile, the predicted Frequency Response Function (FRF) of the spindle based on the rotor dynamics is integrated to the chatter vibration stability law. Consequently, the expert design system enables the structure of machine tools to be designed efficiently with a higher precision. The proposed system was demonstrated through an aerostatic spindle design for micro-array structures machining.     

Design of buckling-induced mechanical metamaterials for energy absorption using topology optimization

A novel design concept for buckling-induced mechanical metamaterials for energy absorption is presented. The force-displacement curves of the mechanical metamaterials are analyzed according to the curves of their unit cells, and the energy-absorbing characteristics of mechanical metamaterials are evaluated. Two topology optimization models are proposed. One maximizes the buckling-induced dissipated energy to facilitate the design of metamaterials with high energy absorption and low elastic strain energy. The other maximizes the dissipated energy with a constraint that the mechanical metamaterials should be self-recoverable. An energy interpolation scheme is employed to avoid numerical instabilities in the geometric nonlinear finite element analysis. A two-phase algorithm is proposed to find the optimized result from a uniform initial guess, and sensitivity analysis is performed. The optimized design has a larger amount of buckling-induced dissipated energy than the previously proposed structural prototypes. Moreover, the self-recoverable mechanical metamaterial is successfully designed by topology optimization.