Siak Piang Lim

Bio: Siak Piang Lim is an academic researcher from National University of Singapore. The author has contributed to research in topics: Ultrasonic motor & Isotropy. The author has an hindex of 29, co-authored 100 publications receiving 3168 citations. Previous affiliations of Siak Piang Lim include Singapore–MIT alliance & Institute of High Performance Computing Singapore.

Modeling and analysis of micro piezoelectric power generators for micro-electromechanical-systems applications

Abstract: The extremely small size of the micro-electromechanical systems (MEMS) makes them widely suitable for some special applications. The simplicity of the piezoelectric micro-generators is attractive for MEMS applications, especially for remote systems. In this paper, a general concept of the piezoelectric energy conversion is first given. A simple design modeling and analysis of the ‘31’ transverse mode type piezoelectric micro-generator is presented. The output power is taken as the indicated parameters for the generator. The energy conversion efficiency of the generator, which is dependent on the operation frequency, is expressed in the frequency domain. A case study of laminated type micro-generators using PZT-PIC 255 for MEMS applications is given and the use of single crystal PZN-8% PT is also studied for comparison. Some design guidelines are presented based on the simulation results.

Piezoelectric ultrasonic micromotor with 1.5 mm diameter

Abstract: A piezoelectric ultrasonic micromotor has been developed using a lead zirconate titanate (PZT) ceramic/metal composite tube stator that was 1.5 mm in diameter and 7 mm in length. The micromotor was operated in its first bending vibration mode (/spl sim/70 kHz), producing speeds from hundreds to over 2000 rpm in both rotational directions. The maximum torque-output was 45 /spl mu/N-m, which is far superior to previous PZT thin film-based micromotors. This micromotor showed good reliability and stability for more than 300 hours of continued operation.

Hybrid energy harvester based on piezoelectric and electromagnetic mechanisms

Abstract: A novel hybrid energy harvester integrated with piezoelectric and electromagnetic energy harvesting mechanisms is investigated. It contains a piezoelectric cantilever of multilayer piezoelectric transducer (PZT) ceramics, permanent magnets, and substrate of two-layer coils. The effect of the relative position of coils and magnets on the PZT cantilever end and the poling direction of magnets on the output voltage of the energy harvester is explored. When the poling direction of magnets is normal to the coils plane, the coils yield the maximum output voltage, i.e., the type I and III devices. The maximum output voltage and power from the PZT cantilever of the type III device are 0.84 V and 176 µW under the vibrations of 2.5-g acceleration at 310 Hz, respectively. And the maximum output voltage and power from the coils are 0.78 mV and 0.19 µW under the same conditions, respectively. The power density from the type III device is derived as 790 µW/cm3 from piezoelectric components and 0.85 µW/cm3 from electromagnetic elements.

Multiferroic magnetoelectric composites: Historical perspective, status, and future directions

Abstract: Multiferroic magnetoelectric materials, which simultaneously exhibit ferroelectricity and ferromagnetism, have recently stimulated a sharply increasing number of research activities for their scientific interest and significant technological promise in the novel multifunctional devices. Natural multiferroic single-phase compounds are rare, and their magnetoelectric responses are either relatively weak or occurs at temperatures too low for practical applications. In contrast, multiferroic composites, which incorporate both ferroelectric and ferri-/ferromagnetic phases, typically yield giant magnetoelectric coupling response above room temperature, which makes them ready for technological applications. This review of mostly recent activities begins with a brief summary of the historical perspective of the multiferroic magnetoelectric composites since its appearance in 1972. In such composites the magnetoelectric effect is generated as a product property of a magnetostrictive and a piezoelectric substance. A...

Energy harvesting vibration sources for microsystems applications

Abstract: This paper reviews the state-of-the art in vibration energy harvesting for wireless, self-powered microsystems. Vibration-powered generators are typically, although not exclusively, inertial spring and mass systems. The characteristic equations for inertial-based generators are presented, along with the specific damping equations that relate to the three main transduction mechanisms employed to extract energy from the system. These transduction mechanisms are: piezoelectric, electromagnetic and electrostatic. Piezoelectric generators employ active materials that generate a charge when mechanically stressed. A comprehensive review of existing piezoelectric generators is presented, including impact coupled, resonant and human-based devices. Electromagnetic generators employ electromagnetic induction arising from the relative motion between a magnetic flux gradient and a conductor. Electromagnetic generators presented in the literature are reviewed including large scale discrete devices and wafer-scale integrated versions. Electrostatic generators utilize the relative movement between electrically isolated charged capacitor plates to generate energy. The work done against the electrostatic force between the plates provides the harvested energy. Electrostatic-based generators are reviewed under the classifications of in-plane overlap varying, in-plane gap closing and out-of-plane gap closing; the Coulomb force parametric generator and electret-based generators are also covered. The coupling factor of each transduction mechanism is discussed and all the devices presented in the literature are summarized in tables classified by transduction type; conclusions are drawn as to the suitability of the various techniques.

Metaheuristics: From Design to Implementation

Abstract: A unified view of metaheuristics This book provides a complete background on metaheuristics and shows readers how to design and implement efficient algorithms to solve complex optimization problems across a diverse range of applications, from networking and bioinformatics to engineering design, routing, and scheduling. It presents the main design questions for all families of metaheuristics and clearly illustrates how to implement the algorithms under a software framework to reuse both the design and code. Throughout the book, the key search components of metaheuristics are considered as a toolbox for: Designing efficient metaheuristics (e.g. local search, tabu search, simulated annealing, evolutionary algorithms, particle swarm optimization, scatter search, ant colonies, bee colonies, artificial immune systems) for optimization problems Designing efficient metaheuristics for multi-objective optimization problems Designing hybrid, parallel, and distributed metaheuristics Implementing metaheuristics on sequential and parallel machines Using many case studies and treating design and implementation independently, this book gives readers the skills necessary to solve large-scale optimization problems quickly and efficiently. It is a valuable reference for practicing engineers and researchers from diverse areas dealing with optimization or machine learning; and graduate students in computer science, operations research, control, engineering, business and management, and applied mathematics.

A review of power harvesting using piezoelectric materials (2003–2006)

Abstract: The field of power harvesting has experienced significant growth over the past few years due to the ever-increasing desire to produce portable and wireless electronics with extended lifespans. Current portable and wireless devices must be designed to include electrochemical batteries as the power source. The use of batteries can be troublesome due to their limited lifespan, thus necessitating their periodic replacement. In the case of wireless sensors that are to be placed in remote locations, the sensor must be easily accessible or of a disposable nature to allow the device to function over extended periods of time. Energy scavenging devices are designed to capture the ambient energy surrounding the electronics and convert it into usable electrical energy. The concept of power harvesting works towards developing self-powered devices that do not require replaceable power supplies. A number of sources of harvestable ambient energy exist, including waste heat, vibration, electromagnetic waves, wind, flowing water, and solar energy. While each of these sources of energy can be effectively used to power remote sensors, the structural and biological communities have placed an emphasis on scavenging vibrational energy with piezoelectric materials. This article will review recent literature in the field of power harvesting and present the current state of power harvesting in its drive to create completely self-powered devices.

How to Solve It: Modern Heuristics

Abstract: I What Are the Ages of My Three Sons?.- 1 Why Are Some Problems Difficult to Solve?.- II How Important Is a Model?.- 2 Basic Concepts.- III What Are the Prices in 7-11?.- 3 Traditional Methods - Part 1.- IV What Are the Numbers?.- 4 Traditional Methods - Part 2.- V What's the Color of the Bear?.- 5 Escaping Local Optima.- VI How Good Is Your Intuition?.- 6 An Evolutionary Approach.- VII One of These Things Is Not Like the Others.- 7 Designing Evolutionary Algorithms.- VIII What Is the Shortest Way?.- 8 The Traveling Salesman Problem.- IX Who Owns the Zebra?.- 9 Constraint-Handling Techniques.- X Can You Tune to the Problem?.- 10 Tuning the Algorithm to the Problem.- XI Can You Mate in Two Moves?.- 11 Time-Varying Environments and Noise.- XII Day of the Week of January 1st.- 12 Neural Networks.- XIII What Was the Length of the Rope?.- 13 Fuzzy Systems.- XIV Everything Depends on Something Else.- 14 Coevolutionary Systems.- XV Who's Taller?.- 15 Multicriteria Decision-Making.- XVI Do You Like Simple Solutions?.- 16 Hybrid Systems.- 17 Summary.- Appendix A: Probability and Statistics.- A.1 Basic concepts of probability.- A.2 Random variables.- A.2.1 Discrete random variables.- A.2.2 Continuous random variables.- A.3 Descriptive statistics of random variables.- A.4 Limit theorems and inequalities.- A.5 Adding random variables.- A.6 Generating random numbers on a computer.- A.7 Estimation.- A.8 Statistical hypothesis testing.- A.9 Linear regression.- A.10 Summary.- Appendix B: Problems and Projects.- B.1 Trying some practical problems.- B.2 Reporting computational experiments with heuristic methods.- References.