scholarly journals Analysis and Experimental Validation of a Piezoelectric Harvester with Enhanced Frequency Bandwidth

Materials ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1243 ◽  
Author(s):  
Haim Abramovich ◽  
Idan Har-nes
Keyword(s):  
Natural Frequency ◽  
Analytical Model ◽  
Vibrational Energy ◽  
Total Output ◽  
Frequency Bandwidth ◽  
Parametric Investigation ◽  
Two Factors ◽  
Set Up ◽  
Spring Constants ◽  
Advanced System

The use of a single bimorph as a harmonic oscillator aimed at harvesting vibrational energy is not effective due to its inherent narrow frequency bandwidth stemming from the need to adjust the natural frequency of the harvester to the platform excitation frequencies. Therefore, the present research focuses on the development, manufacturing, and testing of an advanced system based on three bimorphs, capable of adjusting their natural frequencies using tip end masses, and interconnected by springs, thus enlarging the system’s bandwidth. An analytical model was developed for three bimorphs interconnected by two springs with three end masses. The model can predict the output generated voltage from each bimorph, and then the total output power is measured on a given outside resistor as a function of the material properties, the geometric dimensions of the vibrating beams, the end-masses, and the spring constants. The analytical model was then compared with data in the literature, yielding a good correlation. To further increase the reliability of the model, a test set-up was designed and manufactured that included three bimorphs with three end-masses connected by two springs. The system was excited using a shaker, and the output voltage was measured for each bimorph for various configurations. Then, the analytical model was tuned based on the test results by introducing two factors, the quality and the stiffness factors, and the predictions of the calibrated analytical model were compared with the experimental results, yielding a good correlation. The calibrated analytical model was then used to perform a comprehensive parametric investigation for two and three bimorphs systems, in which the influences of various parameters—like spring constant, mass value, thickness, and width and length of the bimorph and the substrate beam—on the output generated power were investigated. The main conclusion from this parametric investigation was that by correctly choosing the geometric sizes of the cantilevers, the adequate tip end masses, and the ratio between constants of the springs, the frequency bandwidth is expanded yielding a higher harvested power. Typical harvested power of the present designed system can reach up to 20 mW at the first natural frequency and up to 5 mW for the second natural frequency.

Optimum Design for the Frame of Open Type Abrasive Flow Polish Machine

2012 ◽  
Vol 497 ◽  
pp. 89-93
Author(s):  
Liang Liang Yuan ◽  
Ke Hua Zhang ◽  
Li Min
Keyword(s):  
Finite Element ◽  
Natural Frequency ◽  
Finite Element Methods ◽  
Optimization Design ◽  
Low Cost ◽  
Three Dimensional ◽  
Force Model ◽  
Optimization Analysis ◽  
Open Type ◽  
Set Up

In order to process heterotype hole of workpiece precisely, an open abrasive flow polish machine is designed, and the optimization design of machine frame is done for low cost. Firstly, basing on the parameters designed with traditional ways, three-dimensional force model is set up with the soft of SolidWorks. Secondly, the statics and modal analysis for machine body have been done in Finite element methods (FEM), and then the optimization analysis of machine frame has been done. At last, the model of rebuild machine frame has been built. Result shows that the deformation angle value of machine frame increased from 0.72′ to 1.001′, the natural frequency of the machine decreased from 75.549 Hz to 62.262 Hz, the weight of machine decreased by 74.178 Kg after optimization. It meets the strength, stiffness and angel stiffness requirement of machine, reduces the weight and cost of machine.

scholarly journals CONTRACTING-OUT OF HOUSEHOLD WASTE COLLECTION SERVICES IN JAPAN

2017 ◽  
Vol 65 (02) ◽  
pp. 443-455
Author(s):  
NORIMICHI MATSUEDA ◽  
JUN’ICHI MIKI
Keyword(s):  
Analytical Model ◽  
Inverse Relationship ◽  
Municipal Waste ◽  
Household Waste ◽  
Private Firms ◽  
Simple Analytical Model ◽  
Waste Collection ◽  
Contracting Out ◽  
Contract Price ◽  
Set Up

We first report three empirical findings from our survey on the contracting-out of municipal waste collection services in Japan: (1) the rate of contracting-out and the contract price are inversely related, (2) this inverse relationship tapers out as the contracting rate becomes sufficiently high, and the contract price even tends to go up as the contracting rate approaches 100% and (3) there is a significant disparity in the contracting rates between the eastern and western parts of Japan. In order to account for these observations, we then set up a simple analytical model and examine its implications. Also, we discuss the issues that a potential hold-up situation could give rise to when the services are completely contracted out to private firms.

Chinese women's autonomy: parenthood as a choice

2020 ◽  
Vol 3 (2) ◽  
pp. 255-266
Author(s):  
Shelly Volsche ◽  
William Jankowiak
Keyword(s):  
Inner Mongolia ◽  
Filial Piety ◽  
Intergenerational Relationships ◽  
Chinese Society ◽  
Moral Code ◽  
Chinese Youth ◽  
Chinese Studies ◽  
Two Factors ◽  
Set Up ◽  
College Educated

Numerous Chinese studies point out that Chinese youth are transforming the meaning of filial piety, China's highly esteemed moral code used to structure intergenerational relationships. We wanted to understand the extent to which college educated women are redefining what it means to be a filial woman in contemporary Chinese society. To this end, we set up a research design that probed whether men and women continue to think becoming parents is an essential attribute of life satisfaction using a pen-and-paper survey with college students in Shanghai and Hohhot, Inner Mongolia. A Principal Components Analysis (PCA) on Likert-scaled questions resulted in two factors: Customary Ideology and Autonomous Self. As anticipated, students who reported their intent to parent were more likely to agree with items in Customary Ideology, whilst students who reported not intending to have children or were uncertain were more likely to agree with items in Autonomous Self. Most telling, an overwhelming number of respondents from each university reported agreement with the statement, "Having children is a personal choice" (97.6% at Fudan University; 76.4% at Inner Mongolia University). We discuss the implications of these findings as the singleton generations renegotiate expectations of these intergenerational bonds.

Product Choice Strategy for Online Retailers

2011 ◽  
pp. 220-238
Author(s):  
Ruiliang Yan ◽  
Amit Bhatnagar
Keyword(s):  
Product Category ◽  
Product Categories ◽  
Online Retailers ◽  
Two Factors ◽  
Brick And Mortar ◽  
Online Channel ◽  
Online Stores ◽  
Set Up ◽  
The Right ◽  
The Web

An important strategic issue for managers planning to set up online stores is the choice of product categories to retail. While the “right” product category would depend on a number of factors, here we focus on the following two factors: compatibility of the product with the online channel, and the competition between the traditional brick and mortar channel and the online channel. This is to acknowledge two well-known facts: Certain products are more suitable for selling through the Web than through other channels; and an online retailer competes with not only other online retailers, but also traditional brick and mortar retailers. To determine the right product category, we develop a game theoretical model that allows for competition between the retailers. We study both Stackelberg and Bertrand competition models, as these two models capture the essence of different types of competition on the Web. Based on our results, we propose that, under all types of competition, the optimal product is one that is only moderately compatible with the Internet.

scholarly journals A simulation study with a new residual ionospheric error model for GPS radio occultation climatologies

2015 ◽  
Vol 8 (8) ◽  
pp. 3395-3404 ◽  
Author(s):  
J. Danzer ◽  
S. B. Healy ◽  
I. D. Culverwell
Keyword(s):  
Simulation Study ◽  
Radio Occultation ◽  
Three Dimensional ◽  
Error Model ◽  
Residual Error ◽  
New Model ◽  
Gps Radio Occultation ◽  
Two Factors ◽  
Set Up ◽  
L1 And L2

Abstract. In this study, a new model was explored which corrects for higher order ionospheric residuals in Global Positioning System (GPS) radio occultation (RO) data. Recently, the theoretical basis of this new "residual ionospheric error model" has been outlined (Healy and Culverwell, 2015). The method was tested in simulations with a one-dimensional model ionosphere. The proposed new model for computing the residual ionospheric error is the product of two factors, one of which expresses its variation from profile to profile and from time to time in terms of measurable quantities (the L1 and L2 bending angles), while the other describes the weak variation with altitude. A simple integral expression for the residual error (Vorob’ev and Krasil’nikova, 1994) has been shown to be in excellent numerical agreement with the exact value, for a simple Chapman layer ionosphere. In this case, the "altitudinal" element of the residual error varies (decreases) by no more than about 25 % between ~10 and ~100 km for physically reasonable Chapman layer parameters. For other simple model ionospheres the integral can be evaluated exactly, and results are in reasonable agreement with those of an equivalent Chapman layer. In this follow-up study the overall objective was to explore the validity of the new residual ionospheric error model for more detailed simulations, based on modeling through a complex three-dimensional ionosphere. The simulation study was set up, simulating day and night GPS RO profiles for the period of a solar cycle with and without an ionosphere. The residual ionospheric error was studied, the new error model was tested, and temporal and spatial variations of the model were investigated. The model performed well in the simulation study, capturing the temporal variability of the ionospheric residual. Although it was not possible, due to high noise of the simulated bending-angle profiles at mid- to high latitudes, to perform a thorough latitudinal investigation of the performance of the model, first positive and encouraging results were found at low latitudes. Furthermore, first application tests of the model on the data showed a reduction in temperature level of the ionospheric residual at 40 km from about −2.2 to −0.2 K.

GENETIC VARIATION IN DIURETIC RESPONSES TO WATER LOADS: DEFINITION OF SOME PARAMETERS OF DIURETIC RESPONSE AND INITIAL RESULTS OF SELECTION FOR THESE PARAMETERS

1965 ◽  
Vol 33 (3) ◽  
pp. 417-428 ◽  
Author(s):  
J. STEWART ◽  
S. G. SPICKETT
Keyword(s):  
Genetic Variation ◽  
Disruptive Selection ◽  
Total Output ◽  
Water Load ◽  
Diuretic Response ◽  
Set Up ◽  
Definition Of ◽  
Response To Water ◽  
The Relationship ◽  
Initial Results

SUMMARY Three parameters of the diuretic response to a water load are defined these are: diuretic lag, rate of diuresis and total output/input. A heterogeneous stock of mice was set up using the strains A/Cam, CBA/FaCam, SF/Cam and Peru. Directional selection was made from this stock for rate of diuresis, and total output/input. The initial generations of selection showed positive and significant parent-offspring regressions and hence demonstrated genetic variation in these parameters. Two positive disruptive selection experiments were set up to explore the relationship between diuretic lag at 4 and 8 weeks of age. These experiments show also that there is genetic variation in diuretic lag and that gene manifestation at 4 weeks and at 8 weeks is different. The genetic variation affecting diuretic response to water load is discussed with respect to concepts of 'normal' physiology.

scholarly journals A simulation study with a new residual ionospheric error model for GPS radio occultation climatologies

2015 ◽  
Vol 8 (1) ◽  
pp. 1151-1176 ◽  
Author(s):  
J. Danzer ◽  
S. B. Healy ◽  
I. D. Culverwell
Keyword(s):  
Simulation Study ◽  
Radio Occultation ◽  
Three Dimensional ◽  
Error Model ◽  
Residual Error ◽  
New Model ◽  
Gps Radio Occultation ◽  
Two Factors ◽  
Set Up ◽  
L1 And L2

Abstract. In this study, a new model was explored, which corrects for higher order ionospheric residuals in global positioning system (GPS) radio occultation (RO) data. Recently, the theoretical basis of this new "residual ionospheric error model" has been outlined (Healy and Culverwell, 2015). The method was tested in simulations with a one-dimensional model ionosphere. The proposed new model for computing the residual ionospheric error is the product of two factors, one of which expresses its variation from profile-to-profile and from time-to-time in terms of measurable quantities (the L1 and L2 bending angles), the other of which describes the weak variation with altitude. A simple integral expression for the residual error (Vorob’ev and Krasil’nikova, 1994) has been shown to be in excellent numerical agreement with the exact value, for a simple Chapman layer ionosphere. In this case, the "altitudinal" element of the residual error varies (decreases) by no more than about 25% between ~10 and ~100 km for physically reasonable Chapman layer parameters. For other simple model ionospheres the integral can be evaluated exactly, and results are in reasonable agreement with those of an equivalent Chapman layer. In this follow-up study the overall objective was to explore the validity of the new residual ionospheric error model for more detailed simulations, based on modelling through a complex three-dimensional ionosphere. The simulation study was set up, simulating day and night GPS RO profiles for the period of a solar cycle with and without an ionosphere. The residual ionospheric error was studied, the new error model was tested, and temporal and spatial variations of the model were investigated. The model performed well in the simulation study, capturing the temporal variability of the ionospheric residual. Although, it was not possible, due to high noise of the simulated bending angle profiles at mid to high latitudes, to perform a thorough latitudinal investigation of the performance of the model, first positive and encouraging results were found at low latitudes. Furthermore, first application tests of the model on the data showed a reduction on temperature level of the ionospheric residual at 40 km from about −2.2 to −0.2 K.

Vibration Control of Offshore Platforms Using a Wideband METMD System

2006 ◽  
Author(s):  
Dong Zhao ◽  
Rujian Ma ◽  
Dongmei Cai
Keyword(s):  
Vibration Control ◽  
Natural Frequency ◽  
Fem Simulation ◽  
Average Frequency ◽  
Offshore Platforms ◽  
Frequency Bandwidth ◽  
Wave Load ◽  
Control Effect ◽  
Exciting Frequency ◽  
Specific Frequency

A wideband multiple extended tuned mass dampers (METMD) system has been developed for reducing the multiple resonant responses of the platforms to all kinds of loads, such as earthquake, typhoon, tsunami and big ice load. This system is composed of several subsystems, each of which consists of one set of extended tuned mass damper (ETMD) unit covering a specific frequency bandwidth, and its average frequency is tuned to one of the first resonant frequencies of the platform. The offshore platform is simplified to a single degree-of-freedom (DOF) system to which a METMD subsystem (composed of m ETMDs) is attached and constitutes m+1 DOFs system. The total mass ratio of the METMD subsystem to the platform is 14% and the frequency ratio of the exciting frequency to the platform’s natural frequency varies in [0.5, 1.5]. The theory analysis shows that: 1) the platform has the better vibration control effect when the non-dimensional frequency bandwidth Ω, which is defined as the ratio of the frequency range to the controlled (target) platforms natural frequency, is in [0.35, 0.6]; 2) the damping coefficient ξ of ETMD systems is in [0.05, 0.15] and 3) the number of the ETMDs is 5 when Ω = 0.45 and ξ = 0.1. The FEM simulation shows that the METMD has a better vibration control effect on the mega-platforms’ vibration control under the random ocean wave load.

Waiting for the Payday? The Market for Startups and the Timing of Entrepreneurial Exit

2020 ◽  
Author(s):  
Ashish Arora ◽  
Andrea Fosfuri ◽  
Thomas Rønde
Keyword(s):  
Analytical Model ◽  
Business Strategy ◽  
Exit Strategy ◽  
Trade Off ◽  
Early Exit ◽  
Early Acquisition ◽  
Set Up ◽  
Exclusive Choice ◽  
Early Market ◽  
Technology Startups

Most technology startups are set up for exit through acquisition by large corporations. In choosing when to sell, startups face a trade-off. Early acquisition reduces execution errors, but later acquisition both improves the likelihood of finding a better match and benefits from increased buyer competition. Startups’ exit strategies vary considerably: Some startups aim to sell early; others remain in stealth mode by developing the invention for a late sale. We develop an analytical model to study the timing of the exit strategy. We find that startups with more capable founding teams commit to a late exit, whereas those with less capable founding teams commit to an early exit. Finally, startups with founding teams of intermediate capabilities remain flexible: They seek early offers but eventually sell late. If trying the early market is so costly that startups have to make a mutually exclusive choice between an early and late sale, startups sell inefficiently late. Instead, if they can collect early offers at no cost before deciding on the timing of sale, there are too many early acquisitions. This paper was accepted by David Simchi-Levi, business strategy.

Analysis of Vibration Characteristics of Magnetorheological Elastomer Sandwich Beam under Non-Homogeneous Magnetic Field

2011 ◽  
Vol 101-102 ◽  
pp. 202-206 ◽  
Author(s):  
Guo Liang Hu ◽  
Miao Guo ◽  
Wei Hua Li
Keyword(s):  
Magnetic Field ◽  
Natural Frequency ◽  
Sandwich Beam ◽  
Homogeneous Magnetic Field ◽  
Experimental Results ◽  
Magnetorheological Elastomer ◽  
Test Rig ◽  
Thin Aluminum ◽  
Set Up ◽  
The Magnetic Field

In this study, the MRE was manufactured, and the sandwich beam was also fabricated by treating with MRE between two thin aluminum layers. The experiment test rig was set up to investigate the vibration response of the MRE sandwich beam under non-homogeneous magnetic field. The experimental results show that the MRE sandwich beam had the capabilities of left shifting first natural frequency when the magnetic field was increased in the activated regions. It is also obvious that the first natural frequency of the MRE sandwich beam decreased as the magnetic field that applied on the beam was moved from the clamped end of the beam to the free end of the beam.

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