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Article

Parnasree Chakraborty and C. Tharini

The purpose of this paper is to find out the use of compressive sensing (CS) algorithm for wireless sensor networks (WSNs). As energy-efficient algorithms are required for…

Abstract

Purpose

The purpose of this paper is to find out the use of compressive sensing (CS) algorithm for wireless sensor networks (WSNs). As energy-efficient algorithms are required for WSNs, CS is very much useful as less than 25 per cent of the entire input data alone is required to be transmitted, and reconstruction at the receiver with this reduced data set is of good quality. But, the usefulness of the algorithm with suitable modulation schemes is not analyzed so far in the literature. Hence, this work concentrated on the algorithm performance with different modulation schemes and different channel conditions.

Design/methodology/approach

Compressive sensing encoding is performed by using suitable transform on the input signal. Here, DCT and DWT are used to generate the sparse signal. Random measurement matrix is used to generate the compressed output, which is reconstructed using the Basis Pursuit (BP) method. Also, an analysis for the energy-efficient modulation scheme is performed by modulating the compressed output using QPSK/BPSK/QAM and transmitted by considering the Gaussian and Rayleigh Channels. Energy required per bit transmission is modeled and computed for different schemes.

Findings

Simulation result shows that the use of CS algorithm for data compression tremendously reduces the number of transmission bits and, hence, enhances the transmission and bandwidth efficiency in WSN. Results show that DWT is a much suitable transform to be used for sparse measurement generation. In comparison with DCT, DWT is computationally simple and takes very less time, which is expected in real-time application. The reconstruction result shows that about 25 per cent of the data sample is sufficient to recover the original image, perhaps which is the most surprising result. An extensive analysis of various modulation schemes based on the energy model shows that QPSK is in the AWGN channel, and QAM modulation in the Rayleigh channel is a much suitable modulation scheme to be used in WSN for further reduction of energy consumption.

Originality/value

Compressive sensing is recently gaining importance for quantization, compression and noise removal in images. In this paper, this technique was used along with modulation schemes to analyze the suitability of the algorithm for WSN.

Details

Sensor Review, vol. 35 no. 2
Type: Research Article
ISSN: 0260-2288

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Article

Gilbert Azuela and Linda Robertson

Workshops are commonly used to up-skill staff and their usefulness can be determined by measuring whether or not learning needs have been met and, in particular, whether…

Abstract

Purpose

Workshops are commonly used to up-skill staff and their usefulness can be determined by measuring whether or not learning needs have been met and, in particular, whether attitudes have changed. In the field of mental health, sensory modulation workshops have been introduced to educate staff about preventative measures that reduce the use of seclusion and restraint for service users with challenging behaviours. The purpose of this paper is to evaluate the impact of such a workshop.

Design/methodology/approach

A one-day workshop was developed based on a review of the literature and feedback from previous workshops, and with input from an industry-based reference group. An evaluation tool was designed to measure the learning outcomes, i.e., the knowledge, skills, and attitudes of the 23 participants. The Statistical Package for the Social Sciences (SPSS v20) was used to analyse the data. Multi-variate analysis of variance was used to determine the relationship between variables.

Findings

A significant increase in the knowledge, skills, and attitudes of mental health staff was identified after the one-day workshop (F=106.346, df=1, p<0.000). When considering which participants showed most benefits, it was shown that the demographics had no effect, i.e., education level, practice discipline, years of work experience in mental health, and previous sensory modulation training.

Practical implications

Measuring learning outcomes provides essential information about whether or not the learning objectives have been met. This allows future workshops to be tailored to ensure that the learning opportunity is at the correct level for the learners. More traditional evaluations that elicit the views of the content covered and teaching methods should additionally be used to supplement this information.

Originality/value

Workshops are often evaluated on the basis of the participants’ subjective response to a quick questionnaire. Developing a tool to measure outcomes is a more effective way to determine what has been learned and to ensure that positive outcomes for individuals and their organisations can be reached.

Details

The Journal of Mental Health Training, Education and Practice, vol. 11 no. 5
Type: Research Article
ISSN: 1755-6228

Keywords

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Article

Wojciech Pietrowski, Wojciech Ludowicz and Rafal Marek Wojciechowski

The specific modulation methods are used to control different kind of single-phase, as well as three-phase, inverters to ensure flexibility and high quality of the output…

Abstract

Purpose

The specific modulation methods are used to control different kind of single-phase, as well as three-phase, inverters to ensure flexibility and high quality of the output waveform. This paper aims to present a combination of two classical methods, namely, pulse width modulation method and direct digital synthesis modulation method.

Design/methodology/approach

The total harmonic distortion of output waveforms of single-phase inverter based on elaborated modulation method has been determined by means of fast Fourier transform analysis. Tests have been carried out by using standard low-frequency application and also a wireless resonant energy link system.

Findings

Applying appropriate timer parameters of microcontroller enables to obtain a waveform for given output parameters (amplitude, frequency, frequency modulation index, etc.). The only limitation is the computing power of a microcontroller.

Originality/value

The elaborated method can be successfully used in both low- and high-frequency application ensuring high level of output waveform quality. Additional signal generators and the control of amplitude modulation ratio are no longer indispensable, what simplify immensely a control system.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 38 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

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Article

BALASUBRAMANIAM RAMASWAMY

Sinusoidal gravity modulation fields imposed on two‐dimensional Rayleigh‐Benard convection flow are studied to understand the effects of periodic source (g‐jitter) on…

Abstract

Sinusoidal gravity modulation fields imposed on two‐dimensional Rayleigh‐Benard convection flow are studied to understand the effects of periodic source (g‐jitter) on fluids system and heat transfer mechanism. The transient Navier‐Stokes and energy equations are solved by semi‐implicit operator splitting finite element method. Results include two sets. One is considered at normal terrestrial condition and the other one is related to low‐gravity condition. Under low‐gravity condition the research focuses on the effects of modulation frequency and direction in order to find out the critical frequency for heat transfer mechanism transferring from conduction to convection.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 3 no. 5
Type: Research Article
ISSN: 0961-5539

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Article

Marianne Obé and Roger E. Khayat

The purpose of this paper is to investigate the thermal convection inside a spatially modulated domain.

Abstract

Purpose

The purpose of this paper is to investigate the thermal convection inside a spatially modulated domain.

Design/methodology/approach

The governing equations are mapped onto an infinite strip, allowing Fourier expansion of the flow and temperature in the streamwise direction.

Findings

Similar to Rayleigh‐Benard convection, conduction is lost to convection at a critical Rayleigh number, which depends strongly on both the modulation amplitude and the wavenumber. The effect of modulation is found to be destabilizing (stabilizing) for conduction for relatively large (small) modulation wavelength. Oscillatory convection sets in as the Rayleigh number is increased.

Originality/value

This paper presents novel results.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 20 no. 1
Type: Research Article
ISSN: 0961-5539

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Article

Nguyen Xuan Quyen, Vu Van Yem, Thang Manh Hoang and Kyandoghere Kyamakya

This paper presents and investigates a method named M×N‐ary chaotic pulse‐width‐position modulation (CPWPM) which is based on the combination of M‐ary chaotic…

Abstract

Purpose

This paper presents and investigates a method named M×N‐ary chaotic pulse‐width‐position modulation (CPWPM) which is based on the combination of M‐ary chaotic pulse‐position modulation (CPPM) and N‐ary chaotic pulse‐width modulation (CPWM) in order to provide a better performance in noise‐affected environments as well as improve significantly bit rate.

Design/methodology/approach

Analysis of schemes for modulator and demodulator are presented in detail through describing the schemes of the individual methods and their combination. Theoretical evaluation of bit‐error rate (BER) performance in presence of additive white Gaussian noise (AWGN) is provided. Chaotic behavior with tent map in variation of modulation parameters is also investigated. In order to verify the theoretical analyses, numerical simulations are carried out and their results are reported.

Findings

Both evaluation and simulation results show that when the number of symbols increases, the bit rate is improved significantly but the BER performance is just slightly worse. This makes M×N‐ary CPWPM become an effective method for chaos‐based digital communication.

Originality/value

Although CPPM, CPWM and M‐ary modulation methods have been described in the literature separately, their combination is presented and investigated for the first time in this paper.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 32 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

Content available
Article

Stefan Gebhardt and Richard von Georgi

A psychiatric population (n=123) was examined on how music preferences had changed after the onset of a mental disorder. Most patients did not change their previous music…

Abstract

A psychiatric population (n=123) was examined on how music preferences had changed after the onset of a mental disorder. Most patients did not change their previous music preference; this group of patients considered music helpful for their mental state, showed more attractivity and enforcement as personality traits and used music more for emotion modulation. Patients who experienced a preference shift reported that music had impaired them during the time of illness; these patients showed less ego-strength, less confidence and less enforcement and used music less for arousal modulation. A third subgroup stopped listening to music completely after the onset of the mental disorder; these patients attribute less importance to music and also reported that music had impaired their mental state. They showed more ego-strength and used music less for emotion modulation. The results suggest that the use of music in everyday life can be helpful as an emotion modulation strategy. However, some patients might need instructions on how to use music in a functional way and not a dysfunctional one. Psychiatrists and psychotherapists as well as music therapists should be aware of emotion modulation strategies, subjective valence of music and personality traits of their patients. Due to the ubiquity of music, psychoeducative instructions on how to use music in everyday life plays an increasing role in the treatment of mental illness.

Details

Mental Illness, vol. 7 no. 1
Type: Research Article
ISSN: 2036-7465

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Article

Thomas M. Wolbank and Mohamed K. Metwally

The purpose of this paper is to describe an effective method to eliminate or substantially reduce the modulation harmonics due to saturation and inter‐modulation for…

Abstract

Purpose

The purpose of this paper is to describe an effective method to eliminate or substantially reduce the modulation harmonics due to saturation and inter‐modulation for sensorless speed control induction motor drives at low and zero speed with high loads using artificial neural networks (ANNs).

Design/methodology/approach

In this paper, the separation of the saturation signal, the slotting signal, and the inter‐modulation signal components in squirrel cage induction machines operating at low and zero frequency using ANNs has been experimentally implemented and measurement results are given.

Findings

The measurement results show the advantages of the application of the proposed technique at low and zero speed sensorless control even at high load levels.

Originality/value

The paper describes an effective method of eliminating or reducing modulation harmonics in induction motor drives.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 29 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

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Article

Yan Zhao, L.T. Si and H. Ouyang

A novel frequency domain approach, which combines the pseudo excitation method modified by the authors and multi-domain Fourier transform (PEM-FT), is proposed for…

Abstract

Purpose

A novel frequency domain approach, which combines the pseudo excitation method modified by the authors and multi-domain Fourier transform (PEM-FT), is proposed for analyzing nonstationary random vibration in this paper.

Design/methodology/approach

For a structure subjected to a nonstationary random excitation, the closed-form solution of evolutionary power spectral density of the response is derived in frequency domain.

Findings

The deterministic process and random process in an evolutionary spectrum are separated effectively using this method during the analysis of nonstationary random vibration of a linear damped system, only modulation function of the system needs to be estimated, which brings about a large saving in computational time.

Originality/value

The method is general and highly flexible as it can deal with various damping types and nonstationary random excitations with different modulation functions.

Details

Engineering Computations, vol. 35 no. 2
Type: Research Article
ISSN: 0264-4401

Keywords

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Article

Fardin Hasanzad, Hasan Rastegar and Mohammad Pichan

This paper aims to investigate the common-mode voltage (CMV) issue of a three-phase four-leg voltage-source inverter. A new space vector modulation method, named as…

Abstract

Purpose

This paper aims to investigate the common-mode voltage (CMV) issue of a three-phase four-leg voltage-source inverter. A new space vector modulation method, named as three-dimensional active zero state Pulse-width modulation (PWM) (3-D AZSPWM), is proposed to reduce the CMV level.

Design/methodology/approach

PWM is a general method to generate the switching signals of the power converters in order to obtain high-quality output voltages. However, the CMV produced by PWM methods has become a serious problem. 3-D AZSPWM is proposed to solve this issue. In 3-D AZSPWM, instead of using zero voltage vectors with high CMV level, appropriate complementary non-zero vectors are introduced to synthesize reference vector. The proposed method is classified into four types of AZSPWM1(a), AZSPWM1(b), AZSPWM2(a) and AZSPWM2(b) based on different complementary vectors chosen for each type. An extend software simulation using MATLAB/Simulink is performed to verify the superior performance of the proposed methods.

Findings

Compared to other reduced CMV methods, the proposed method not only reduces the CMV but also retains the positive characteristics of the three-dimensional classical space vector PWM (3-D CSVPWM).

Originality/value

The proposed method does not suffer from linear modulation region limitation and also does not impose additional switching loss. Furthermore, calculated output voltage harmonic distortion factor illuminates acceptable quality of output voltage produced by the proposed method.

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