Analytical study on effect of ring geometry on frequency shift of piezoelectric ring-shaped resonator

Ring-shaped resonators with one and four-point-outer-pinned supports have been designed in this work. The ring-shaped resonator reacts with a mass perturbation to provide eigenstate or frequency shifts which could transfer to electrical signals by piezoelectric effect. The aforementioned ring-shaped resonator is mainly comprised with a multilayer of Pt/Ti/PZT/Pt/Ti/SiO₂ deposited on the silicon-on-insulator wafer and expected to be a contour mode. In order to estimate the sensitivity of the ring-shaped resonator against the mass perturbation, the theoretical analysis was conducted by ANSYS from two aspects including: (a) the view point of geometrical design and (b) the mass application methodology. When a mass perturbation (i.e., a liquid droplet) of 10?pg is homogeneously contacting on the top electrode of the resonator, frequency shifts from 2.11 to 4.07?kHz could be obtained when excited in the contour mode. Furthermore, the more stabled vibration behavior of resonator with four-point-pinned supports was approved by the computer stimulation of ANSYS analysis results.     

Coupling element effect on support loss of coupled oscillators for mass and analyte sensing applications

Microsystem Technologies - The nonlinear synchronous resonance or internal resonance in coupled oscillators has great potential for sensing applications, while a higher quality factor is desirable...     

Design and optimization of MEMS piezoelectric energy harvester for low frequency applications

Microsystem Technologies - Piezoelectric vibrational energy harvester (PVEH) suits best for harvesting vibrational energy from the environment due to the simplicity in design, operation, and...     

Investigation on the geometry of beams for piezoelectric energy harvester

Microsystem Technologies - This paper presents various designs of the cantilever based piezoelectric energy harvester, which is excited using mechanical vibrations at the fixed end. By varying the...     

Designing and analyzing of a piezoelectric energy harvester with tunable system natural frequency for WSN and biosensing applications

A new structure for PEH with actuation piezoelectric layer for shifting natural frequency of the system is proposed. Beams are consisted to be Si and AlN piezoelectric which is deposited on fixed–fixed beams that produces high stress points and generates more power in comparison to the other cantilever beam PEHs. This PEH with ability of shifting system natural frequency is designed to the size of 0.25 cm² using optimum available space. Actuation piezoelectric layers added on both sides of the beams provides possibility of continues reducing systems natural frequency to less than 10 Hz. Accomplished simulation also confirms theoretical calculation done by PDE method to estimate natural frequency of the system. The natural frequency of the system without actuation voltage is 58 Hz that with 1 g acceleration generated 4.27 V and 71 µW electrical power which can be used in WSN and biosensing applications.

     

An exploratory study of radio frequency identification (RFID) adoption in the healthcare industry

This study examines the radio frequency identification (RFID) adoption decision process and proposes a model predicting the likelihood of adopting RFID within organizations in the healthcare industry. A considerable number of studies have been conducted regarding organizational information technology (IT) adoption, but the nature of the organizational IT adoption process is still not well understood. Especially, although there are a number of variables and categories that have been found empirically to be related to adoption behavior, there is little in the way of evidence to suggest the origin or motivation behind the adoption. Thus, this study investigates the underlying motivations and driving forces behind the adoption of RFID using the theory of technology-push and need-pull. In this study, an organizational RFID adoption model is proposed and empirically tested by a survey using a sample of 126 senior executives in U.S. hospitals. The model posits that three categories of factors, technology push, need pull, and presence of champions, determine the likelihood of adopting RFID within organizations. This study also found that the relationships between those three categories and the likelihood of adopting RFID are strengthened or weakened by organizational readiness.     

Block diagrams of a multilayer piezoelectric motor for nano- and microdisplacements based on the longitudinal piezoelectric effect

Block diagrams of a multilayer piezoelectric motor based on the longitudinal piezoelectric effect with account for the electromotive counterforce are designed. Transfer functions of the piezoelectric motor with regard to its geometric and physical parameters, electromotive counterforce, and external load are obtained.     

An effective method for grasp planning on objects with complex geometry combining human experience and analytical approach

Science China Information Sciences - In this paper, an effective method for identifying the graspable components of objects with complex geometry is proposed for grasp planning based on human...     

最小化多MapReduce任务总完工时间的分析模型及其应用

随着大规模的MapReduce集群广泛地用于大数据处理,特别是当有多个任务需要使用同一个Hadoop集群时,一个关键问题是如何最大限度地减少集群的工作时间,提高MapReduce作业的服务效率。可将多个MapReduce作业当做一个调度任务建模,观察发现多个任务的总完工时间和任务的执行顺序有密切关系。 研究目标是设计作业调度系统分析模型,最小化一批MapReduce作业的总完工时间。提出一个更好的调度策略和实现方法, 使整个调度系统符合经典Johnson算法的条件, 从而可使用经典Johnson算法在线性时间内获取总完工时间的最优解。同时,针对需要使用两个或多个资源池进行平衡的问题, 提出了一种线性时间解决方案, 优于已知的近似模拟方案。该理论模型可应用于提高系统响应速度、节能和负载均衡等方面, 对应的应用实例提供了证实。     

An algorithm for the construction of intrinsic delaunay triangulations with applications to digital geometry processing

Summary The discrete Laplace–Beltrami operator plays a prominent role in many digital geometry processing applications ranging from denoising to parameterization, editing, and physical simulation. The standard discretization uses the cotangents of the angles in the immersed mesh which leads to a variety of numerical problems. We advocate the use of the intrinsic Laplace–Beltrami operator. It satisfies a local maximum principle, guaranteeing, e.g., that no flipped triangles can occur in parameterizations. It also leads to better conditioned linear systems. The intrinsic Laplace–Beltrami operator is based on an intrinsic Delaunay triangulation of the surface. We detail an incremental algorithm to construct such triangulations together with an overlay structure which captures the relationship between the extrinsic and intrinsic triangulations. Using a variety of example meshes we demonstrate the numerical benefits of the intrinsic Laplace–Beltrami operator.     

Modeling of the intrinsic stress effect on the resonant frequency of NEMS resonators integrated by beams with variable cross-section

Nano-electro-mechanical systems (NEMS) resonators integrated by a double clamped beam with variable cross-section are used in several applications such as chemical and biological detectors, high-frequency filters, and signal processing. The structure of these resonators can experience intrinsic stresses produced during their fabrication process. We present an analytical model to estimate the first bending resonant frequency of NEMS resonators based on a double clamped beam with three cross-sections, which considers the intrinsic stress effect on the resonant structure. This model is obtained using the Rayleigh and Macaulay methods, as well as the Euler–Bernoulli beam theory. We applied the analytical model to a silicon carbide (SiC) resonator of 186 nm thickness reported in the literature. This resonator has a total length ranking from 80 to 258 μm and is subjected to a tensile intrinsic stress close to 110 MPa. Results from this model show good agreement with experimental results. The analytic frequencies have a maximum relative difference less than 6.3% respect to the measured frequencies. The tensile intrinsic stress on the resonant structure causes a significantly increase on its bending resonant frequency. The proposed model provides an insight into the study of the intrinsic stress influence on the resonant frequency of this nanostructure. In addition, this model can estimate the frequency shift due to the variations of the resonator geometrical parameters.     

An analytical and numerical study of the two-dimensional Bratu equation

Bratu's problem, which is the nonlinear eigenvalue equationu+ exp(u)=0 withu=0 on the walls of the unit square and as the eigenvalue, is used to develop several themes on applications of Chebyshev pseudospectral methods. The first is the importance ofsymmetry: because of invariance under the C₄ rotation group and parity in bothx andy, one can slash the size of the basis set by a factor of eight and reduce the CPU time by three orders of magnitude. Second, the pseudospectral method is ananalytical as well as a numerical tool: the simple approximation3.2A exp(–0.64A), whereA is the maximum value ofu(x, y), is derived via collocation with but a single interpolation point, but is quantitatively accurate for small and moderateA. Third, the Newton-Kantorovich/Chebyshev pseudospectral algorithm is so efficient that it is possible to compute good numerical solutions—five decimal places—on amicrocomputer inbasic. Fourth, asymptotic estimates of the Chebyshev coefficients can be very misleading: the coefficients for moderately or strongly nonlinear solutions to Bratu's equations fall off exponentially rather than algebraically withv untilv is so large that one has already obtained several decimal places of accuracy. The corner singularities, which dominate the behavior of the Chebyshev coefficients in thelimit v, are so weak as to be irrelevant, and replacing Bratu's problem by a more complicated and realistic equation would merely exaggerate the unimportance of the corner branch points even more.     

一种基于压电效应的振动能量收集电路

为了收集环境中的振动能量,实现传感器等低能耗器件的自供能,设计了一种可收集环境中低频机械振动能量的发电电能收集电路,通过三倍压电路将压电晶体产生的交流电压进行倍压放大,利用LTC3588-1电源管理芯片中的低噪声全波整流及高效降压转换器进行变换,获得可为传感器等低能耗器件供电的直流电压。分析与实验表明,设计的振动能量收集电路可为传感器等器件提供电能,实现微弱电能的收集。     

An analytical model on the blocking probability of a fault-tolerantnetwork

The well-known Clos network has been extensively used for telephone switching, multiprocessor interconnection and data communications. Much work has been done to develop analytical models for understanding the routing blocking probability of the Clos network. However, none of the analytical models for estimating the blocking probability of this type of network have taken into account the very real possibility of the interstage links in the network failing. In this paper, we consider the routing between arbitrary network inputs and outputs in the Clos network in the presence of interstage link faults. In particular, we present an analytical model for the routing blocking probability of the Clos network which incorporates the probability of interstage link failure to allow for a more realistic and useful determination of the approximation of blocking probability. We also conduct extensive simulations to validate the model. Our analytical and simulation results demonstrate that for a relatively small interstage link failure probability, the blocking behavior of the Clos network is similar to that of a fault-free network, and indicate that the Clos network has a good fault-tolerant capability. The new integrated analytical model can guide network designers in the determination of the effects of network failure on the overall connecting capability of the network and allows for the examination of the relationship between network utilization and network failure     

A piezoelectric solid shell element based on a mixed variational formulation for geometrically linear and nonlinear applications

The paper is focused on a piezoelectric solid shell finite element formulation. A geometrically nonlinear theory allows large deformations and includes stability problems. The formulation is based on a variational principle of the Hu–Washizu type including six independent fields: displacements, electric potential, strains, electric field, mechanical stresses and dielectric displacements. The element has eight nodes with displacements and the electric potential as nodal degrees of freedom. A bilinear distribution through the thickness of the electric field is assumed to obtain correct results in bending dominated situations. The presented element is able to model arbitrary curved shells and incorporates a 3D-material law. Numerical examples demonstrate the ability of the proposed model to analyze piezoelectric devices.     

Effects of perspective elevation and environmental geometry on representation of a virtual room space

The present study investigated how perspective elevation and room geometry influenced mental representation of spatial layout in virtual rooms. One virtual rectangular and one virtual cylindrical room were constructed. Subjects observed the spatial layout on the floor from five perspectives along the vertical dimension of each virtual room. Then they judged the direction of objects with respect to egocentric and canonical coordinates. The analysis of spatial judgment indicated that judgment accuracy of vertical direction decreased as the perspective elevated, while global situation awareness was best maintained at the 45° elevation angle. The effect of perspective elevation on judgment of horizontal direction was only found in the rectangular room. Moreover, subjects judged the relative direction between objects more quickly in the cylindrical room than in the rectangular room. Applications of these findings to virtual environment design were discussed.     

An analytical study of central and in-network data processing for wireless sensor networks

This paper compares the performance of centralized and in-network data processing for wireless sensor networks (WSNs) under various deployment conditions on the real sensor hardware Sun SPOT from Sun Microsystems. We define several criteria to measure the quality of responses in WSN applications. Guided by an extensive experimental study, we discuss in detail the performance impacts of different deployment factors on algorithms that implement both centralized and in-network computing. Finally, performance guidelines are given to algorithm designers for WSN applications.     

Versatile CAD formulation for estimation of the resonant frequency and magnetic polarizability of circular split ring resonators

In this article, we propose a theoretical formulation to estimate the resonant frequency and magnetic polarizability of a circular split ring resonator (SRR). The computed results are compared with experimental and simulation results revealing excellent agreement for a wide range of frequencies. The proposed theory was compared with simulation for different parametric variation of the SRR. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.