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Article
Publication date: 12 August 2021

Guoda Wang, Ping Li, Yumei Wen and Zhichun Luo

Existing control circuits for piezoelectric energy harvesting (PEH) suffers from long startup time or high power consumption. This paper aims to design an ultra-low power

Abstract

Purpose

Existing control circuits for piezoelectric energy harvesting (PEH) suffers from long startup time or high power consumption. This paper aims to design an ultra-low power control circuit that can harvest weak ambient vibrational energy on the order of several microwatts to power heavy loads such as wireless sensors.

Design/methodology/approach

A self-powered control circuit is proposed, functioning for very brief periods at the maximum power point, resulting in a low duty cycle. The circuit can start to function at low input power thresholds and can promptly achieve optimal operating conditions when cold-starting. The circuit is designed to be able to operate without stable DC power supply and powered by the piezoelectric transducers.

Findings

When using the series-synchronized switch harvesting on inductor circuit with a large 1 mF energy storage capacitor, the proposed circuit can perform 322% better than the standard energy harvesting circuit in terms of energy harvested. This control circuit can also achieve an ultra-low consumption of 0.3 µW, as well as capable of cold-starting with input power as low as 5.78 µW.

Originality/value

The intermittent control strategy proposed in this paper can drastically reduce power consumption of the control circuit. Without dedicated cold-start modules and DC auxiliary supply, the circuit can achieve optimal efficiency within one input cycle, if the input signal is larger than voltage threshold. The proposed control strategy is especially favorable for harvesting energy from natural vibrations and can be a promising solution for other PEH circuits as well.

Details

Circuit World, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 15 October 2021

Paulthurai Rajesh, Francis H. Shajin and Kumar Cherukupalli

The purpose of this paper is to track the maximal power of wind energy conversion system (WECS) and enhance the search capability for WECS maximum power point tracking (MPPT).

Abstract

Purpose

The purpose of this paper is to track the maximal power of wind energy conversion system (WECS) and enhance the search capability for WECS maximum power point tracking (MPPT).

Design/methodology/approach

The hybrid technique is the combination of tunicate swarm algorithm (TSA) and radial basis function neural network.

Findings

TSA gets input parameters from the rectifier outputs such as rectifier direct current (DC) voltage, DC current and time. From the input parameters, it enhances the reduced fault power of rectifier and generates training data set based on the MPPT conditions. The training data set is used in radial basis function. During the execution time, it produces the rectifier reference DC side voltage that is converted to control pulses of inverter switches.

Originality/value

Finally, the proposed method is executed in MATLAB/Simulink site, and the performance is compared with different existing methods like particle swarm optimization algorithm and hill climb searching technique. Then the output illustrates the performance of the proposed method and confirms its capability to solve issues.

Details

Journal of Engineering, Design and Technology , vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1726-0531

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Article
Publication date: 19 October 2021

Saja Albelali and Steve Williams

The paper investigates the implications for gendered power relations at work of Nitaqat, a workforce localization policy operating in Saudi Arabia which, by regulating the…

Abstract

Purpose

The paper investigates the implications for gendered power relations at work of Nitaqat, a workforce localization policy operating in Saudi Arabia which, by regulating the employment of Saudi nationals in private sector firms, has stimulated greater feminization of employment.

Design/methodology/approach

Based on an interpretivist, phenomenological research approach, rich qualitative data were collected in two case study organizations – a retail company and an architectural firm. The mixed-method design involved in-depth interviews with managers and women workers and extensive non-participant observation.

Findings

In exploring gendered power relations in Saudi private sector workplaces under the Nitaqat regime, the paper highlights the importance of patriarchal power. However, increased feminization of employment provides women workers with access to power resources of their own, producing complexity and variation in gendered workplace power relations.

Originality/value

Drawing on Bradley's (1999) relational conception of gendered power, the paper illuminates how a Nitaqat-inspired feminization of employment, by increasing firms' dependency on women workers, has influenced the dynamics of gendered power relations in Saudi workplaces.

Details

Employee Relations: The International Journal, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0142-5455

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Article
Publication date: 11 October 2021

Jialin Song, Yiyi Su, Taoyong Su and Luyu Wang

The purpose of this paper is, from a resource accumulation and resource allocation perspective, to examine the variant effects of government subsidies among firms with…

Abstract

Purpose

The purpose of this paper is, from a resource accumulation and resource allocation perspective, to examine the variant effects of government subsidies among firms with varying levels of market power and to test how industry competition moderates the relationship between market power and allocative efficiency of government subsidies.

Design/methodology/approach

This study explores the relationship between government subsidies and firm performance from a resource-based view. The authors study the moderating role of market power and three-way interaction between subsidy, market power and industry competition on firm performance. The authors test their hypotheses using a sample of Chinese A-share manufacturing firms from 2006–2019. The authors apply firm-level panel data regressions and conduct a series of robustness tests. The marginal effect of market power and industry competition is explored via three-way moderator effect models.

Findings

This study finds that government subsidies are negatively related to firm performance. Market power, on average, strengthens the negative effect of government subsidies on performance, but such a reinforcement effect is neutralized when industry competition is intense. Government subsidies are least efficiently used when firms have market power and industry competition is low. In addition, the authors use different forms of firm performance and a various of robustness tests to verify their assumptions.

Originality/value

This paper contributes to the literature as follows. First, the authors look into subsidy–performance problem from the perspective of the resource-based view and contribute to explaining and mitigating the divergence of current findings on the subsidy–performance relationship. Second, the authors introduce market power and industry competition as moderators to study how resource allocative efficiency affects the subsidy–performance relationship. Third, the authors propose that managerial incentives have played an important role in the allocation of government subsidies, which enriches management practices.

Details

Chinese Management Studies, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1750-614X

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Book part
Publication date: 7 September 2012

Sangin Park

This chapter proposes three different definitions for the market power in the antitrust case, such as dynamic monopoly power, static monopoly power and market power.The…

Abstract

This chapter proposes three different definitions for the market power in the antitrust case, such as dynamic monopoly power, static monopoly power and market power.

The chapter presents simple economic models to analyse which definition of the three market powers is consistent with predatory pricing or tying.

The prerequisite market power is simply market power in the predatory pricing case or static monopoly power in the tying case.

Dynamic monopoly power defined as the market power from an antitrust perspective by the Antitrust Modernization Commission should not be the prerequisite market power in the case of the abuse of dominance or the violation of Section 2 of the Sherman Act.

A possession of substantial market power or monopoly power is typically understood as a prerequisite in abuse of dominance in Korea and EU or violation of Section 2 of the Sherman Act in the United States. However, the antitrust law does not clearly indicate the meaning of market power or monopoly power. This chapter proposes three different definitions for the market power in the antitrust case and analyses which definition of the three market powers is consistent with predatory pricing or tying.

Details

Research in Law and Economics
Type: Book
ISBN: 978-1-78052-898-4

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Article
Publication date: 22 September 2021

Nora Moran and Sigalit Ronen

Consumers can provide monetary tips to service employees as a reward for their efforts. However, consumers’ ability to recognize the demands of these jobs could affect…

Abstract

Purpose

Consumers can provide monetary tips to service employees as a reward for their efforts. However, consumers’ ability to recognize the demands of these jobs could affect tipping behavior. This study aims to examine the difficulty consumers have recognized the emotional toll of service work, and how this affects tipping behavior.

Design/methodology/approach

Three experiments were conducted with US participants to determine how the focus on emotional burdens of service work affects willingness to tip lower level service employees.

Findings

Results reveal that when consumers hear about the emotional costs of service labor, they report less willingness to tip low-level workers, compared to when they learn about other job costs or contributions. Results further show that reducing power distance between customers and workers can increase willingness to tip when emotional costs are emphasized.

Research limitations/implications

This research contributes to the services literature by showing how feelings of power affect whether consumers appreciate certain job costs, and, in turn, their tipping behavior.

Practical implications

This research clarifies how consumers perceive job demands, which has direct consequences for tipping behavior and suggests more strategies to improve tips.

Social implications

Findings can help advocates looking to advance the status and compensation for lower-level service workers.

Originality/value

This research is first to explore why the emotional costs of service labor are not recognized in certain cases, and provides insight on how to improve customer treatment of lower-level service labor.

Details

Journal of Services Marketing, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0887-6045

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Article
Publication date: 22 September 2021

A. Prakash, A. Shyam Joseph, R. Shanmugasundaram and C.S. Ravichandran

This paper aims to propose a machine learning approach-based power theft detection using Garra Rufa Fish (GRF) optimization. Here, the analyzing of power theft is an…

Abstract

Purpose

This paper aims to propose a machine learning approach-based power theft detection using Garra Rufa Fish (GRF) optimization. Here, the analyzing of power theft is an important part to reduce the financial loss and protect the electricity from fraudulent users.

Design/methodology/approach

In this section, a new method is implemented to reduce the power theft in transmission lines and utility grids. The detection of power theft using smart meter with reliable manner can be achieved by the help of GRF algorithm.

Findings

The loss of power due to non-technical loss is small by using this proposed algorithm. It provides some benefits like increased predicting capacity, less complexity, high speed and high reliable output. The result is analyzed using MATLAB/Simulink platform. The result is compared with an existing method. According to the comparison result, the proposed method provides the good performance than existing method.

Originality/value

The proposed method gives good results of comparison than those of the other techniques and has an ability to overcome the associated problems.

Details

Journal of Engineering, Design and Technology , vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1726-0531

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Article
Publication date: 5 October 2021

Min Zhang, Cheng Hu, Jingwei Gao and Peng Zheng

Suspension is a significantly important component for automotive and railway vehicles. Regenerative hydraulic-electric shock absorbers (RHSA) have been proposed for the…

Abstract

Purpose

Suspension is a significantly important component for automotive and railway vehicles. Regenerative hydraulic-electric shock absorbers (RHSA) have been proposed for the purpose of attenuating vibration of vehicle suspension, and also recover kinetic energy originated from vehicle vibration that is conventionally dissipated by hydraulic dampers. To advance the technology, the paper aims to present an RHSA system for heavy-duty and railway vehicles and create a dynamic modelling to discuss on the development process of RHSA model.

Design/methodology/approach

First, the development of RHSA dynamic model can be resolved into three stage models (an ideal one, a second one with an added accumulator and a third one that considers both accumulator and system losses) to comprehensively evaluate the RHSA's characterisation. Second, a prototype is fabricated for testing and the results meet desired agreements between simulation and measurement. Finally, the study of key parameters is carried out to investigate the influences of hydraulic-cylinder size, hydraulic-motor displacement and accumulator pre-charged pressure on the RHSA system.

Findings

The findings of sensitivity analysis indicate that the component design can satisfy the damping characteristics and power performance required for heavy-duty vehicle, freight wagon and typical passenger train. The results also show that reducing the losses is highly beneficial for saving suspension energy, improving system reliability and increasing power-conversion efficiency.

Originality/value

The paper presents a more detailed method for the development and analysis of a RHSA. Compared with the typical shock absorbers, RHSA can also recover the vibration energy dissipated by suspension.

Details

Engineering Computations, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 18 August 2021

Gowtham Venkatraman, Adam Hehr, Leon M. Headings and Marcelo J. Dapino

Ultrasonic additive manufacturing (UAM) is a solid-state joining technology used for three-dimensional printing of metal foilstock. The electrical power input to the…

Abstract

Purpose

Ultrasonic additive manufacturing (UAM) is a solid-state joining technology used for three-dimensional printing of metal foilstock. The electrical power input to the ultrasonic welder is a key driver of part quality in UAM, but under the same process parameters, it can vary widely for different build geometries and material combinations because of mechanical compliance in the system. This study aims to model the relationship between UAM weld power and system compliance considering the workpiece (geometry and materials) and the fixture on which the build is fabricated.

Design/methodology/approach

Linear elastic finite element modeling and experimental modal analysis are used to characterize the system’s mechanical compliance, and linear system dynamics theory is used to understand the relationship between weld power and compliance. In-situ measurements of the weld power are presented for various build stiffnesses to compare model predictions with experiments.

Findings

Weld power in UAM is found to be largely determined by the mechanical compliance of the build and insensitive to foil material strength.

Originality/value

This is the first research paper to develop a predictive model relating UAM weld power and the mechanical compliance of the build over a range of foil combinations. This model is used to develop a tool to determine the process settings required to achieve a consistent weld power in builds with different stiffnesses.

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Article
Publication date: 4 August 2021

Lenin Kanagasabai

Purpose of this paper are Real power loss reduction, voltage stability enhancement and minimization of Voltage deviation.

Abstract

Purpose

Purpose of this paper are Real power loss reduction, voltage stability enhancement and minimization of Voltage deviation.

Design/methodology/approach

In HLG approach as per Henry gas law sum of gas dissolved in the liquid is directly proportional to the partial pressure on above the liquid. Gas dissolving in the liquid which based on Henry gas law is main concept to formulate the proposed algorithm. Populations are divided into groups and all the groups possess the similar Henry constant value. Exploration and exploitation has been balanced effectively. Ranking and position of the worst agents is done in order to avoid the local optima. Then in this work Mobula alfredi optimization (MAO) algorithm is projected to solve optimal reactive power problem. Foraging actions of Mobula alfredi has been imitated to design the algorithm. String foraging, twister foraging and backward roll foraging are mathematically formulated to solve the problem. In the entire exploration space the Mobula alfredi has been forced to discover new regions by assigning capricious position. Through this approach, exploration competence of the algorithm has been improved. In all iterations, the position of the Mobula alfredi has been updated and replaced with the most excellent solution found so far. Exploration and exploitation capabilities have been maintained sequentially. Then in this work balanced condition algorithm (BCA) is projected to solve optimal reactive power problem. Proposed BCA approach based on the conception in physics- on the subject of the mass; incoming, exit and producing in the control volume. Preliminary population has been created based on the dimensions and number of particles and it initialized capriciously in the exploration space with minimum and maximum concentration. Production control parameter and Production probability utilized to control the exploration and exploitation.

Findings

Proposed Henry's Law based -soluble gas optimization (HLG) algorithm, Mobula alfredi optimization (MAO) algorithm and BCA are evaluated in IEEE 30 bus system with L-index (Voltage stability) and also tested in standard IEEE 14, 30, 57, 118, 300 bus test systems without L- index. Real power loss minimization, voltage deviation minimization, and voltage stability index enhancement has been attained.

Originality/value

For the first time Henry's Law based -soluble gas optimization (HLG) algorithm, Mobula alfredi optimization (MAO) algorithm and BCA is projected to solve the power loss reduction problem.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 40 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

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