High torque and excessive vibration on the induction motors under special voltage fluctuation conditions

Purpose Voltage fluctuation (flicker) is a power quality disturbance that can produce several undesirable effects on industrial equipment. This paper aims to present the methodology and results of investigations undertaken to examine the speed and torque of an induction motor (IM) under voltage fluctuation conditions. Design/methodology/approach The IM response to different characteristics of voltage fluctuations is presented. It will be shown that under a special condition the IM torque can even reach two times the rated torque. To show how this occurs, a qualitative discussion is given on the motor response by linearized equations. Findings The small-signal analysis was used to determine the frequency which leads to maximum speed fluctuations. It was shown that, if the motor is excited with a modulation frequency (resonant frequency) which is one of its natural frequencies (modes), the mode will act as a fluctuating amplifier and greatly increase the amplitude of torque and speed fluctuations. Sensitivity analysis is also carried out to evaluate the influence of motor parameters on the resonance frequency. The results show that the resonance frequency is not affected at all by the changes in magnetizing reactance. This has been shown that magnetic saturation does not have any impact on the resonance frequency. The most effective parameters are rotor and stator resistances. Originality/value With the increasing popularity and use of arc furnace loads in the metallurgy industry and due to the wide application of large IMs in the industry, it is possible that the frequency of torque pulsation locates near a natural frequency and then will create an oscillation with a large magnitude, potentially leading to accelerated fatigue or severe damage of shaft. However, if this phenomenon occurs in industries, the resonance frequency must be filtered from the input voltage. Experimental results on a 1.1 kW, 380 V, 50 Hz, 2 pole IM are used to validate the accuracy of simulation results.

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Relationship amongst ResearchGate altmetric indicators and Scopus bibliometric indicators

New Library World ◽

10.1108/nlw-03-2015-0017 ◽

2015 ◽

Vol 116 (9/10) ◽

pp. 564-577 ◽

Cited By ~ 10

Author(s):

RISHABH SHRIVASTAVA ◽

Preeti Mahajan

Keyword(s):

Sample Size ◽

Correlation Coefficients ◽

Strong Positive Correlation ◽

Bibliometric Indicators ◽

Pearson’S Correlation ◽

Content Type ◽

Positive Correlation ◽

Pearson's Correlation ◽

Different Characteristics ◽

The Relationship

Purpose – The purpose of this paper is twofold. First, the study aims to investigate the relationship between the altmetric indicators from ResearchGate (RG) and the bibliometric indicators from the Scopus database. Second, the study seeks to examine the relationship amongst the RG altmetric indicators themselves. RG is a rich source of altmetric indicators such as Citations, RGScore, Impact Points, Profile Views, Publication Views, etc. Design/methodology/approach – For establishing whether RG metrics showed the same results as the established sources of metrics, Pearson’s correlation coefficients were calculated between the metrics provided by RG and the metrics obtained from Scopus. Pearson’s correlation coefficients were also calculated for the metrics provided by RG. The data were collected by visiting the profile pages of all the members who had an account in RG under the Department of Physics, Panjab University, Chandigarh (India). Findings – The study showed that most of the RG metrics showed strong positive correlation with the Scopus metrics, except for RGScore (RG) and Citations (Scopus), which showed moderate positive correlation. It was also found that the RG metrics showed moderate to strong positive correlation amongst each other. Research limitations/implications – The limitation of this study is that more and more scientists and researchers may join RG in the future, therefore the data may change. The study focuses on the members who had an account in RG under the Department of Physics, Panjab University, Chandigarh (India). Perhaps further studies can be conducted by increasing the sample size and by taking a different sample size having different characteristics. Originality/value – Being an emerging field, not much has been conducted in the area of altmetrics. Very few studies have been conducted on the reach of academic social networks like RG and their validity as sources of altmetric indicators like RGScore, Impact Points, etc. The findings offer insights to the question whether RG can be used as an alternative to traditional sources of bibliometric indicators, especially with reference to a rapidly developing country such as India.

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Do Twitter phenomena check-in popular venues on Foursquare too?

Information Discovery and Delivery ◽

10.1108/idd-04-2018-0012 ◽

2018 ◽

Vol 46 (3) ◽

pp. 137-146

Author(s):

Aysun Bozanta ◽

Birgul Kutlu

Keyword(s):

Clustering Analysis ◽

Design Methodology ◽

Business Owners ◽

Marketing Strategies ◽

The Other ◽

Shopping Mall ◽

Content Type ◽

History Of ◽

Twitter Users ◽

Different Characteristics

Purpose The purpose of this study is to figure out the visiting behaviors of the users who have different characteristics on Twitter. Design/methodology/approach The visit history of users who share their Foursquare check-ins on Twitter and the characteristics of visited venues (category, check-in count, tip count, like count, rating, and price tier) was collected with Foursquare API. In addition, the number of followers, friends, tweets and favorite-count were collected via Twitter API. First, users were clustered according to their Twitter related attributes. After that, profiling was applied on clusters according to the characteristics of the venues that were visited by the users. Findings Clustering analysis generated three clusters, namely, ordinary, talkative and popular. For each cluster, the visited venues were investigated according to the price classification, check-in, like, tip counts and the categories. The users in ordinary class prefer cheaper venues rather than talkative and popular users. On the other hand, popular users prefer the venues with the highest average number of check-ins, likes and tip counts. The top two categories for all clusters are cafe and shopping mall. Originality/value This study differentiates from the other studies in the literature by examining the data from Twitter with clustering and profiling these clusters with Foursquare data to understand venue preferences of Twitter users having various characteristics. The findings of this study will provide new insights for business owners to understand the customers more comprehensively and design better marketing strategies.

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Molecular Characterization of Commensal Escherichia coli Adapted to Different Compartments of the Porcine Gastrointestinal Tract

Applied and Environmental Microbiology ◽

10.1128/aem.01688-12 ◽

2012 ◽

Vol 78 (19) ◽

pp. 6799-6803 ◽

Cited By ~ 12

Author(s):

Sam Abraham ◽

David M. Gordon ◽

James Chin ◽

Huub J. M. Brouwers ◽

Peter Njuguna ◽

...

Keyword(s):

Escherichia Coli ◽

Gastrointestinal Tract ◽

Random Amplified Polymorphic Dna ◽

Content Type ◽

E Coli ◽

Plasmid Replicon ◽

Different Strains ◽

Different Characteristics

ABSTRACTThe role ofEscherichia colias a pathogen has been the focus of considerable study, while much less is known about it as a commensal and how it adapts to and colonizes different environmental niches within the mammalian gut. In this study, we characterizeEscherichia coliorganisms (n= 146) isolated from different regions of the intestinal tracts of eight pigs (dueodenum, ileum, colon, and feces). The isolates were typed using the method of random amplified polymorphic DNA (RAPD) and screened for the presence of bacteriocin genes and plasmid replicon types. Molecular analysis of variance using the RAPD data showed thatE. coliisolates are nonrandomly distributed among different gut regions, and that gut region accounted for 25% (P< 0.001) of the observed variation among strains. Bacteriocin screening revealed that a bacteriocin gene was detected in 45% of the isolates, with 43% carrying colicin genes and 3% carrying microcin genes. Of the bacteriocins observed (H47, E3, E1, E2, E7, Ia/Ib, and B/M), the frequency with which they were detected varied with respect to gut region for the colicins E2, E7, Ia/Ib, and B/M. The plasmid replicon typing gave rise to 25 profiles from the 13 Inc types detected. Inc F types were detected most frequently, followed by Inc HI1 and N types. Of the Inc types detected, 7 were nonrandomly distributed among isolates from the different regions of the gut. The results of this study indicate that not only may the different regions of the gastrointestinal tract harbor different strains ofE. colibut also that strains from different regions have different characteristics.

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On the role of different annealing heat treatments on mechanical properties and microstructure of selective laser melted and conventional wrought Ti-6Al-4V

Rapid Prototyping Journal ◽

10.1108/rpj-02-2016-0022 ◽

2017 ◽

Vol 23 (2) ◽

pp. 295-304 ◽

Cited By ~ 32

Author(s):

AmirMahyar Khorasani ◽

Ian Gibson ◽

Moshe Goldberg ◽

Guy Littlefair

Keyword(s):

Mechanical Properties ◽

Design Methodology ◽

Stress Relief ◽

Heat Treatments ◽

Recrystallization Annealing ◽

Content Type ◽

Hardness Increase ◽

As Stress ◽

Different Characteristics

Purpose The purpose of this study was to conduct various heat treatments (HT) such as stress relief annealing, mill annealing, recrystallization (α + β) annealing and β annealing followed by furnace cooling (FC) that were implemented to determine the effect of these on mechanical properties and the microstructure of selective laser melted and wrought samples. The mentioned annealings have been carried out to achieve the related standards in the fabrication of surgery implants. Design/methodology/approach In this paper, based on F2924-14 ASTM standard SLM and conventionally wrought parts were prepared. Then HT was performed and different characteristics such as microstructure, mechanical properties, macro-hardness and fracture surface for selective laser melted and wrought parts were analysed. Findings The results show that the high cooling rate in selective laser melting (SLM) generates finer grains. Therefore, tensile strength and hardness increase along with a reduction in ductility was noticed. Recrystallization annealing appears to give the best combination of ductility, strength and hardness for selective laser melted parts, whilst for equivalent wrought samples, increasing HT temperature results in reduction of mechanical properties. Originality/value The contributions of this paper are discussing the effect of different annealing on mechanical properties and microstructural evolution based on new ASTM standards for selective laser melted samples and comparing them with wrought parts.

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Modeling, Design Procedure and Control of a Low-Cost High-Gain Multi-Input Step-Up Converter

Electronics ◽

10.3390/electronics8121424 ◽

2019 ◽

Vol 8 (12) ◽

pp. 1424

Author(s):

Edgardo Netzahuatl ◽

Domingo Cortes ◽

Marco A. Ramirez-Salinas ◽

Jorge Resa ◽

Leobardo Hernandez ◽

...

Keyword(s):

Nonlinear Model ◽

Low Cost ◽

Renewable Energy Sources ◽

Design Procedure ◽

Input Voltage ◽

High Gain ◽

Grid Systems ◽

Real Behavior ◽

Different Characteristics ◽

And Control

The use of several different sources to feed a load jointly is convenient in many applications, in particular those where two or more renewable energy sources are employed. These applications include energy harvesting, hybrid vehicles, and off-grid systems. A multi-input converter able to admit sources of different characteristics and select the output power of each source is necessary in such applications. Several topologies of multi-input converters have been proposed to this aim; however, most of them are controlled by simple strategies based on a small signal model of multi-input converters. In this work, a low cost high gain step-up multi-input converter is analyzed. A nonlinear model is derived. Using this model, a detailed design procedure is proposed. A 500 W converter prototype was constructed to confirm that the model predicted the real behavior of the converter. Using the nonlinear model, indirect voltage control of basic converters was extended to the multi-input converter. The obtained controller had a fast performance, and it was robust under load and input voltage variations. With the obtained model, the proposed design procedure, and the controller, a converter that was initially proposed for photovoltaic applications was enabled to be used in a broader range of applications. The herein exposed ideas for modeling, the design procedure, and control could be also applied to other multi-input converters.

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Dynamic Responses of Electrically Driven Quartz Tuning Fork and qPlus Sensor: A Comprehensive Electromechanical Model for Quartz Tuning Fork

Sensors ◽

10.3390/s19122686 ◽

2019 ◽

Vol 19 (12) ◽

pp. 2686

Author(s):

Manhee Lee ◽

Bongsu Kim ◽

Sangmin An ◽

Wonho Jhe

Keyword(s):

Resonance Frequency ◽

Quality Factor ◽

Tuning Fork ◽

Quartz Tuning Fork ◽

Dynamic Responses ◽

Peak Amplitude ◽

Quantitative Prediction ◽

Dynamic Features ◽

Electromechanical Model ◽

Different Characteristics

A quartz tuning fork and its qPlus configuration show different characteristics in their dynamic features, including peak amplitude, resonance frequency, and quality factor. Here, we present an electromechanical model that comprehensively describes the dynamic responses of an electrically driven tuning fork and its qPlus configuration. Based on the model, we theoretically derive and experimentally validate how the peak amplitude, resonance frequency, quality factor, and normalized capacitance are changed when transforming a tuning fork to its qPlus configuration. Furthermore, we introduce two experimentally measurable parameters that are intrinsic for a given tuning fork and not changed by the qPlus configuration. The present model and analysis allow quantitative prediction of the dynamic characteristics in tuning fork and qPlus, and thus could be useful to optimize the sensors’ performance.

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Nanofluid Thermal Conductivity and Effective Parameters

Applied Sciences ◽

10.3390/app9010087 ◽

2018 ◽

Vol 9 (1) ◽

pp. 87 ◽

Cited By ~ 10

Author(s):

Sarah Simpson ◽

Austin Schelfhout ◽

Chris Golden ◽

Saeid Vafaei

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

Nanoparticle Concentration ◽

Effective Parameters ◽

Conductivity Enhancement ◽

Nanoparticle Shape ◽

Hybrid Nanofluids ◽

Different Characteristics ◽

The Impact ◽

Base Liquid

Due to the more powerful and miniaturized nature of modern devices, conventional heat-transfer working fluids are not capable of meeting the cooling needs of these systems. Therefore, it is necessary to improve the heat-transfer abilities of commonly used cooling fluids. Recently, nanoparticles with different characteristics have been introduced to base liquids to enhance the overall thermal conductivity. This paper studies the influence of various parameters, including base liquid, temperature, nanoparticle concentration, nanoparticle size, nanoparticle shape, nanoparticle material, and the addition of surfactant, on nanofluid thermal conductivity. The mechanisms of thermal conductivity enhancement by different parameters are discussed. The impact of nanoparticles on the enhanced thermal conductivity of nanofluids is clearly shown through plotting the thermal conductivities of nanofluids as a function of temperature and/or nanoparticle concentration on the same graphs as their respective base liquids. Additionally, the thermal conductivity of hybrid nanofluids, and the effects of the addition of carbon nanotubes on nanofluid thermal conductivity, are studied. Finally, modeling of nanofluid thermal conductivity is briefly reviewed.

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Distribution of activity in spinal pathways evoked by experimental dorsal column stimulation

Journal of Neurosurgery ◽

10.3171/jns.1975.42.3.0290 ◽

1975 ◽

Vol 42 (3) ◽

pp. 290-295 ◽

Cited By ~ 20

Author(s):

Heinrich Bantli ◽

James R. Bloedel ◽

Donlin M. Long ◽

Phudhiphorn Thienprasit

Keyword(s):

Rhesus Monkeys ◽

Dorsal Column ◽

Electrode Position ◽

Content Type ◽

Spinal Pathways ◽

Therapeutic Value ◽

Stimulus Parameters ◽

Different Characteristics ◽

Dorsal Column Stimulation ◽

Fine Print

✓ Experiments were performed in rhesus monkeys to determine the distribution of activity evoked in spinal pathways by dorsal column stimulation. It was shown that many pathways in both the dorsal and ventral quadrants of the cord can be activated either directly or transsynaptically by stimulation with electrodes of the type implanted clinically. Moreover, the transsynaptically evoked responses recorded in each quadrant had somewhat different characteristics. Therefore, since the activation of each group of pathways may have differing effects in modifying the perception of noxious stimuli, the authors believe that changes in electrode position and stimulus parameters may be important in obtaining the therapeutic value of spinal cord stimulation for relief of pain.

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The medical leadership challenge in healthcare is an identity challenge

Leadership in Health Services ◽

10.1108/lhs-04-2014-0032 ◽

2015 ◽

Vol 28 (2) ◽

pp. 83-99 ◽

Cited By ~ 28

Author(s):

Thomas Andersson

Keyword(s):

Leadership Skills ◽

Social Identities ◽

Organizational System ◽

Content Type ◽

Qualitative Case Studies ◽

Cooperative Relationships ◽

Psychological Mechanisms ◽

The Social ◽

Medical Leadership ◽

Different Characteristics

Purpose – The purpose of this article is to describe and analyse the identity challenges that physicians with medical leadership positions face. Design/methodology/approach – Four qualitative case studies were performed to address the fact that identity is processual, relational and situational. Physicians with managerial roles were interviewed, as well as their peers, supervisors and subordinates. Furthermore, observations were made to understand how different identities are displayed in action. Findings – This study illustrates that medical leadership implies identity struggles when physicians have manager positions, because of the different characteristics of the social identities of managers and physicians. Major differences are related between physicians as autonomous individuals in a system and managers as subordinates to the organizational system. There are psychological mechanisms that evoke the physician identity more often than the managerial identity among physicians who are managers, which explains why physicians who are managers tend to remain foremost physicians. Research limitations/implications – The implications of the findings, that there are major identity challenges by being both a physician and manager, suggest that managerial physicians might not be the best prerequisite for medical leadership, but instead, cooperative relationships between physicians and non-physician managers might be a less difficult way to support medical leadership. Practical implications – Acknowledging and addressing identity challenges can be important both in creating structures in organizations and designing the training for managers in healthcare (both physicians and non-physicians) to support medical leadership. Originality/value – Medical leadership is most often related to organizational structure and/or leadership skills, but this paper discusses identity requirements and challenges related to medical leadership.

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Particle size characterization as a support for sediment contamination analysis

Management of Environmental Quality An International Journal ◽

10.1108/meq-07-2015-0157 ◽

2017 ◽

Vol 28 (4) ◽

pp. 462-476 ◽

Cited By ~ 4

Author(s):

Felippe Fernandes ◽

Cristiano Poleto

Keyword(s):

Particle Size ◽

Particle Size Analysis ◽

Metropolitan Region ◽

Size Analysis ◽

Content Type ◽

Fine Sediments ◽

Water Courses ◽

Different Depths ◽

Particle Size Characterization ◽

Different Characteristics

Purpose The purpose of this paper is to analyse the results of particle size profiles carried out in the dam Mãe d’água, located in the metropolitan region of Porto Alegre, Rio Grande do Sul, becoming a tool of support for geochemistry evaluation works of sediments in this basin. Design/methodology/approach The methodology comprised the particle size analysis of eight cores sampled using the extraction profile technique “Sampling Cores.” A total of 56 sub-samples were obtained at different depths, varying between 0 and 52 cm. The particle size analysis of the sub-samples was carried out with the protocol relating to Brazilian analysis standards NBR 7,181; for determination of the particle size distribution of thick sediments, the sieve method was used, and for fine sediments, the pipette method was used. Findings The results show that for the different depths, the sediment profiles show similarity in their sedimentary deposition layers. Cores T1, T6, T7 and T8 showed a classification with predominance of mud. Cores T2 and T5 showed variations throughout their sedimentary profile, varying of mud predominance to sand with gravel, and on cores T3 and T4, the predominant characteristic is sand with mud and sand with gravel, respectively. Originality/value It can be seen in this paper that energy of sedimentological flow reaches it in a different way, creating these three sectors (first, sand with gravel; second, sand with mud and third, mud) with different characteristics – morphodynamic and sedimentological. These characteristics are important for the study of the heavy metals on the soil and therefore for reducing the risk of contamination of water courses.

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