Amplified Piezoelectric Stack Actuators for Harvesting Electrical Energy From a Backpack

2007 ◽  
Author(s):  
Joel Feenstra ◽  
Jonathan Granstrom ◽  
Henry A. Sodano
Keyword(s):  
Energy Harvesting ◽  
Experimental Testing ◽  
Electrical Energy ◽  
Wearable Electronics ◽  
The Past ◽  
Higher Power ◽  
Recent Developments ◽  
Battery Technology ◽  
Piezoelectric Stack Actuator ◽  
Made In

Over the past few decades the use of portable and wearable electronics has grown steadily. These devices are becoming increasingly more powerful, however, the gains that have been made in the device performance has resulted in the need for significantly higher power to operate the electronics. This issue has been further complicated due to the stagnate growth of battery technology over the past decade. In order to increase the life of these electronics, researchers have begun investigating methods of generating energy from ambient sources such that the life of the electronics can be prolonged. Recent developments in the field have led to the design of a number of mechanisms that can be used to generate electrical energy, from a variety of sources including thermal, solar, strain, inertia, etc. Many of these energy sources are available for use with humans, but their use must be carefully considered such that parasitic effects that could disrupt the user’s gait or endurance are avoided. This study develops a novel energy harvesting backpack that can generate electrical energy from the differential forces between the wearer and the pack. The goal of this system is to make the energy harvesting device transparent to the wearer such that his or her endurance and dexterity is not compromised. This will be accomplished by replacing the strap buckle with a mechanically amplified piezoelectric stack actuator. Piezoelectric stack actuators have found little use in energy harvesting applications due to their high stiffness which makes straining the material difficult. This issue will be alleviated using a mechanically amplified stack which allows the relatively low forces generated by the pack to be transformed to high forces on the piezoelectric stack. This paper will develop a theoretical model of the piezoelectric buckle and perform experimental testing to validate the model accuracy and energy harvesting performance.

Geometric Optimization of a Piezoelectric Power Harvesting Plate for Increased Bandwidth

2007 ◽  
Author(s):  
Lee Wells ◽  
Yirong Lin ◽  
Henry Sodano ◽  
Byeng Youn
Keyword(s):  
Energy Harvesting ◽  
Electrical Energy ◽  
Maximum Energy ◽  
Geometric Optimization ◽  
Signal Frequency ◽  
Field Energy ◽  
Energy Scavenging ◽  
Power Harvesting ◽  
Topology And Shape Optimization ◽  
Battery Technology

The continual advances in wireless technology and low power electronics have allowed the deployment of small remote sensor networks. However, 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. Furthermore, the growth of battery technology has remained relatively stagnant over the past decade while the performance of computing systems has grown steadily, which leads to increased power usage from the electronics. In the case of wireless sensors that are to be placed in remote locations, the sensor must be easily accessible or of disposable nature to allow the device to function over extended periods of time. For this reason the primary question becomes how to provide power to each node. This issue has spawned the rapid growth of the energy harvesting field. 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. However, when designing a vibration based energy harvesting system the maximum energy generation occurs when the resonant frequency of the system is tuned to the input. This poses certain issues for their practical application because structural systems rarely vibrate at a signal frequency. Therefore, this effort will investigate the optimal geometric design of two dimensional energy harvesting systems for maximized bandwidth. Topology and shape optimization will be used to identify the optimal geometry and experiments will be performed to characterize the energy harvesting improvement when subjected to random vibrations.

scholarly journals Recent Advances in Palladium-Catalyzed Isocyanide Insertions

Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 4906
Author(s):  
Jurriën W. Collet ◽  
Thomas R. Roose ◽  
Bram Weijers ◽  
Bert U. W. Maes ◽  
Eelco Ruijter ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Building Blocks ◽  
Insertion Reactions ◽  
Chemical Reagents ◽  
The Past ◽  
Recent Advances ◽  
Recent Developments ◽  
Palladium Catalyzed ◽  
Made In ◽  
Rapid Incorporation

Isocyanides have long been known as versatile chemical reagents in organic synthesis. Their ambivalent nature also allows them to function as a CO-substitute in palladium-catalyzed cross couplings. Over the past decades, isocyanides have emerged as practical and versatile C1 building blocks, whose inherent N-substitution allows for the rapid incorporation of nitrogeneous fragments in a wide variety of products. Recent developments in palladium catalyzed isocyanide insertion reactions have significantly expanded the scope and applicability of these imidoylative cross-couplings. This review highlights the advances made in this field over the past eight years.

Topology Optimization of Piezoelectric Energy Harvesting Devices Subjected to Stochastic Excitation

2010 ◽  
Author(s):  
Zheqi Lin ◽  
Hae Chang Gea ◽  
Shutian Liu
Keyword(s):  
Topology Optimization ◽  
Energy Harvesting ◽  
Electrical Energy ◽  
Ambient Vibration ◽  
Piezoelectric Energy Harvesting ◽  
The Past ◽  
Piezoelectric Energy ◽  
Random Responses ◽  
Pseudo Excitation ◽  
Energy Harvesting Devices

Converting ambient vibration energy into electrical energy using piezoelectric energy harvester has attracted much interest in the past decades. In this paper, topology optimization is applied to design the optimal layout of the piezoelectric energy harvesting devices. The objective function is defined as to maximize the energy harvesting performance over a range of ambient vibration frequencies. Pseudo excitation method (PEM) is applied to analyze structural stationary random responses. Sensitivity analysis is derived by the adjoint method. Numerical examples are presented to demonstrate the validity of the proposed approach.

A Review of Recent Developments in the Mechanisms of Antifatigue Agents

1985 ◽  
Vol 58 (2) ◽  
pp. 269-283 ◽  
Author(s):  
Gerald Scott
Keyword(s):  
Structural Design ◽  
Material Design ◽  
The Past ◽  
Truck Tires ◽  
Recent Developments ◽  
Shoulder Region ◽  
Major Factors ◽  
High Level ◽  
Vulcanization Process ◽  
Made In

Abstract In spite of the remarkable advances that have been made in the engineering design of tires during the past two decades, the basic formulations used in vulcanization and protection during service have essentially remained unchanged. This is to a large extent due to two major factors: 1. The versatility of the traditional accelerated sulfur curing system which provides the necessary combination of resilience and strength with good resistance to cyclical stress. 2. The development of diarylamine antidegradants which confer a high level of thermal-oxidative and mechano-oxidative (fatigue) resistance to the rubber. Both of these developments have occurred slowly with small incremental improvements and, probably because of their success, relatively little fundamental work has been published which addresses the questions of why a polysulfide network is so resistant to fatigue and why N-sec-alkyl-N′-phenyl-p-phenylenediamines are so much more successful as antidegradants than other classes of antioxidant. It is becoming evident, however, that if tires are to withstand the increasingly demanding conditions to which they are subjected in service, much more attention must be paid to the material design as opposed to the structural design of tires. Nowhere is this more evident than in aircraft tires. Recent studies have shown that the tires of heavily laden wide-bodied aircraft reach temperatures in excess of 70°C at the relatively modest speed of 32 km/h (20 mph). Similarly, in heavy duty truck tires, temperatures over 100°C are not abnormal in the shoulder region. This leads to extensive restructurization of the fatigue resistant polysulfide network, particularly in the shoulder of the tire, to give a much weaker mono-disulfide structure. It is no coincidence then that failure normally occurs in this region. The practice of multiple retreading exacerbates the change in chemical decomposition of the rubber. It is well known to the rubber scientist that extending the vulcanization process also leads to restructurization of the rubber network from polysulfide to mono- and disulfide. This is shown typically for a HAF-black tire formulation at 140°C in Figure 1. Antidegradants have virtually no effect on anaerobic restructurization (see Figure 2), and indeed, the established antifatigue agent, IPPD (I), actually accelerates the loss of polysulfide crosslinks from the vulcanizate at 140°C. During fatiguing, on the other hand, IPPD effectively retards restructurization (see Figure 3), whereas a typical bisphenol, nonstaining antidegradant, II, has much less effect.

scholarly journals Pulsar wind nebulae created by fast-moving pulsars

2017 ◽  
Vol 83 (5) ◽  
Author(s):  
O. Kargaltsev ◽  
G. G. Pavlov ◽  
N. Klingler ◽  
B. Rangelov
Keyword(s):  
Hubble Space Telescope ◽  
Ambient Medium ◽  
Pulsar Wind Nebulae ◽  
The Past ◽  
Recent Developments ◽  
Pulsar Velocity ◽  
Bow Shocks ◽  
Observational Status ◽  
Pulsar Wind ◽  
Made In

We review multiwavelength properties of pulsar wind nebulae created by supersonically moving pulsars and the effects of pulsar motion on the pulsar wind nebulae morphologies and the ambient medium. Supersonic pulsar wind nebulae are characterized by bow-shaped shocks around the pulsar and/or cometary tails filled with the shocked pulsar wind. In the past several years significant advances in supersonic pulsar wind nebula studies have been made in deep observations with the Chandra and XMM-Newton X-ray observatories and the Hubble Space Telescope. In particular, these observations have revealed very diverse supersonic pulsar wind nebula morphologies in the pulsar vicinity, different spectral behaviours of long pulsar tails, the presence of puzzling outflows misaligned with the pulsar velocity and far-UV bow shocks. Here we review the current observational status focusing on recent developments and their implications.

scholarly journals Radiation driven planar foil instability and mix experiments at the AWE HELEN laser

1990 ◽  
Vol 8 (1-2) ◽  
pp. 51-71 ◽  
Author(s):  
J. C. V. Hansom ◽  
P. A. Rosen ◽  
T. J. Goldack ◽  
K. Oades ◽  
P. Fieldhouse ◽  
...  
Keyword(s):  
Spectral Absorption ◽  
Parylene C ◽  
One Dimensional ◽  
The Past ◽  
First Results ◽  
Recent Developments ◽  
Full Analysis ◽  
Point Projection ◽  
Absorption Features ◽  
Made In

This paper reviews recent developments and achievements in the program of planar foil instability experiments being performed at the AWE HELEN laser. Point projection Xray backlighting, with spectroscopy, is used to measure hydrodynamic mix in radiatively accelerated ablator/foil packages; the mix is identified in the experimental radiograph from the overlap of distinguishable spectral absorption features associated with each of the constituent materials.The first part of the paper describes the backlighting technique, and briefly summarizes progress made in the past two years, leading to the first results being obtained on a “high mix” Parylene-C ablator/molybdenum payload package. The second part considers the full analysis of one such ‘high mix’ shot (Shot 7772), describing how the spatial distribution of mix has been quantified and considering the various sources of error. Comparisons are made with both one-dimensional and two-dimensional hydrocode simulations. Finally, various improvements and extensions to the experiment and codes are indicated.

scholarly journals Review of nonlinear vibration energy harvesting: Duffing, bistability, parametric, stochastic and others

2020 ◽  
Vol 31 (7) ◽  
pp. 921-944 ◽  
Author(s):  
Yu Jia
Keyword(s):  
Energy Harvesting ◽  
Nonlinear Vibration ◽  
Electrical Energy ◽  
Rapid Expansion ◽  
Vibration Energy ◽  
Vibration Source ◽  
Vibration Energy Harvesting ◽  
Bandwidth Enhancement ◽  
Advantages And Disadvantages ◽  
The Past

Vibration energy harvesting typically involves a mechanical oscillatory mechanism to accumulate ambient kinetic energy, prior to the conversion to electrical energy through a transducer. The convention is to use a simple linear mass-spring-damper oscillator with its resonant frequency tuned towards that of the vibration source. In the past decade, there has been a rapid expansion in research of vibration energy harvesting into various nonlinear vibration principles such as Duffing nonlinearity, bistability, parametric oscillators, stochastic oscillators and other nonlinear mechanisms. The intended objectives for using nonlinearity include broadening of frequency bandwidth, enhancement of power amplitude and improvement in responsiveness to non-sinusoidal noisy excitations. However, nonlinear vibration energy harvesting also comes with its own challenges and some of the research pursuits have been less than fruitful. Previous reviews in the literature have either focussed on bandwidth enhancement strategies or converged on select few nonlinear mechanisms. This article reviews eight major types of nonlinear vibration energy harvesting reported over the past decade, covering underlying principles, advantages and disadvantages, and application-specific guidance for researchers and designers.

scholarly journals High-performance wearable thermoelectric generator with self-healing, recycling, and Lego-like reconfiguring capabilities

2021 ◽  
Vol 7 (7) ◽  
pp. eabe0586
Author(s):  
Wei Ren ◽  
Yan Sun ◽  
Dongliang Zhao ◽  
Ablimit Aili ◽  
Shun Zhang ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
High Performance ◽  
Electrical Energy ◽  
Open Circuit ◽  
Solar Irradiation ◽  
Self Healing ◽  
Wearable Electronics ◽  
Design Concepts ◽  
Electrical Wiring ◽  
Energy Harvesting Devices

Thermoelectric generators (TEGs) are an excellent candidate for powering wearable electronics and the “Internet of Things,” due to their capability of directly converting heat to electrical energy. Here, we report a high-performance wearable TEG with superior stretchability, self-healability, recyclability, and Lego-like reconfigurability, by combining modular thermoelectric chips, dynamic covalent polyimine, and flowable liquid-metal electrical wiring in a mechanical architecture design of “soft motherboard-rigid plugin modules.” A record-high open-circuit voltage among flexible TEGs is achieved, reaching 1 V/cm2 at a temperature difference of 95 K. Furthermore, this TEG is integrated with a wavelength-selective metamaterial film on the cold side, leading to greatly improved device performance under solar irradiation, which is critically important for wearable energy harvesting during outdoor activities. The optimal properties and design concepts of TEGs reported here can pave the way for delivering the next-generation high-performance, adaptable, customizable, durable, economical, and eco-friendly energy-harvesting devices with wide applications.

scholarly journals Flexible Smart Material With Excellent Energy Harvesting

2021 ◽  
Author(s):  
Nabil Chakhchaoui ◽  
Rida Farhan ◽  
Yu-Ming Chu ◽  
Umair Khan ◽  
Adil Eddiai ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Piezoelectric Material ◽  
Polyvinylidene Fluoride ◽  
Piezoelectric Element ◽  
Electrical Energy ◽  
Smart Structure ◽  
Flexible Substrates ◽  
Power Harvesting ◽  
The Past

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. The present work aims to introduce an approach to harvesting electrical energy from a mechanically excited piezoelectric element and investigates a power analytical model generated by a smart structure of type polyvinylidene fluoride(PVDF) that can be stuck onto fabrics and flexible substrates, although we report the effects of various substrates and investigates the sticking of these substrates on the characterization of the piezoelectric material.

Development and Status of Economic Criminal Law in Germany

2014 ◽  
Vol 15 (4) ◽  
pp. 693-718
Author(s):  
Marc Engelhart
Keyword(s):  
Criminal Law ◽  
Criminal Behavior ◽  
Criminal Policy ◽  
Economic Crime ◽  
The Public ◽  
The Past ◽  
Illegal Behavior ◽  
The Status ◽  
Recent Developments ◽  
Made In

During the past decade, economic crime has been in the public focus in Germany like never before. Major cases, such as the embezzlement proceedings against former Deutsche Bank CEO Ackermann—the so-calledMannesmannproceedings—or the corruption incidents within the Siemens group, have shed more light on illegal behavior in the economic sector. These cases revived an interest in economic criminal law that had not been present since the 1980s when the first wave of economic crime regulation after the establishment of economic criminal law as an academic subject and as a central part of criminal policy had passed. This article analyzes the status and development of economic criminal law. First, it will deal with criminological aspects before turning to the forces in economic crime development. Second, it will examine the changes made in substantive, procedural, and soft law. It includes recent developments, such as the privatization of public investigations and the concept of compliance, as a means to prevent and discover criminal behavior.

Sign in / Sign up

Export Citation Format

Share Document