Reza Ebrahimi, Mostafa Ghayour and Heshmatallah Mohammad Khanlo
This paper aims to present bifurcation analysis of a magnetically supported coaxial rotor model in auxiliary bearings, which includes gyroscopic moments of disks and geometric…
Abstract
Purpose
This paper aims to present bifurcation analysis of a magnetically supported coaxial rotor model in auxiliary bearings, which includes gyroscopic moments of disks and geometric coupling of the magnetic actuators.
Design/methodology/approach
Ten nonlinear equations of motion were solved using the Runge–Kutta method. The vibration responses were analyzed using dynamic trajectories, power spectra, Poincaré maps, bifurcation diagrams and the maximum Lyapunov exponent. The analysis was carried out for different system parameters, namely, the inner shaft stiffness, inter-rotor bearing stiffness, auxiliary bearing stiffness and disk position.
Findings
It was shown that dynamics of the system could be significantly affected by varying these parameters, so that the system responses displayed a rich variety of nonlinear dynamical phenomena, including quasi-periodicity, chaos and jump. Next, some threshold values were provided with regard to the design of appropriate parameters for this system. Therefore, the proposed work can provide an effective means of gaining insights into the nonlinear dynamics of coaxial rotor–active magnetic bearing systems with auxiliary bearings in the future.
Originality/value
This paper considered the influences of the inner shaft stiffness, inter-rotor bearing stiffness, auxiliary bearing stiffness and disk position on the bifurcation behavior of a magnetically supported coaxial rotor system in auxiliary bearings.
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Alireza Fallahi, Fatemeh Fallahi, Hassan Sarhadi, S.F. Ghaderi and Reza Ebrahimi
This study evaluates the efficiency and productivity change of 39 electricity distribution companies in Iran over the period 2005-2014. For purposes of electricity management and…
Abstract
Purpose
This study evaluates the efficiency and productivity change of 39 electricity distribution companies in Iran over the period 2005-2014. For purposes of electricity management and utilization of scarce resources, Iran’s 33 provinces have been classified into five regions by the Ministry of the Interior. Analyzing the efficiency of distribution companies across these regions yields significant understanding of these resources and helps policymakers to generate more informed decisions.
Design/methodology/approach
The proposed method of this study develops nonparametric data envelopment analysis (DEA) with the consideration of geographic classification, size and type of company. At the first stage, a DEA model is used to estimate the relative technical efficiency and productivity change of these companies. At the second stage, distributions of efficiency improvements are examined based on geographic classification, size and type of the company type. A stability test is also conducted to verify the proposed model’s robustness.
Findings
The results demonstrate that the average technical efficiency of the companies increased during the years 2006-2009, but decreased during 2010-2014. The productivity measurement reveals that low efficiency change was the largest contributor to the small increase in productivity change rather than technology change. In addition, testing the hypothesis that the large and small companies have statistically the same efficiency scores revealed no statistical difference among them. Moreover, another test did not detect a difference among companies at the urban and provincial levels.
Practical implications
By applying this approach, policymakers and practitioners in the power industry at the country and corporate level can effectively compare the efficiency and productivity changes among electricity distribution companies, and therefore generate more informed decisions.
Originality/value
The paper’s novel concept applies DEA to Iran’s electricity distribution companies and analyzes them by examining geographic classification, size and the type of the companies. In addition, a stability test is conducted and productivity changes are estimated.
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Miralam Mahdi, Mehrzad Shams and Reza Ebrahimi
The purpose of this paper is to study numerically the effects of heat transfer on the strength of shock waves emitted upon spherical bubble collapse.
Abstract
Purpose
The purpose of this paper is to study numerically the effects of heat transfer on the strength of shock waves emitted upon spherical bubble collapse.
Design/methodology/approach
The motion of bubble under ultrasound is predicted by solutions of the Navier‐Stokes equations for the gas inside a spherical bubble. The Gilmore model and the method of characteristics are used to model the shock wave emitted at the end of the bubble collapse.
Findings
The theory permits one to predict correctly the bubble radius‐time curve and the characteristics of shock wave in sulphuric acid solution. These simulations indicated that the heat transfer inside the bubble and the liquid layer plays a major role in the bubble behaviour and the strength of the shock waves. Also, the developed numerical scheme is checked for different gas bubble like air, Argon and Xenon. It is observed that the gas thermal conductivity plays an important role in the shock wave strength. A good agreement is observed by comparison of the results with the experimental data.
Originality/value
The effect of heat transfer on the emitted shock wave strength has not been studied previously. In this paper, a numerical scheme is developed to consider heat transfer on the shock. Also, this simulation is checked for different gas conductivities.
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Reza Ghazavi and Haidar Ebrahimi
Groundwater is an important source of water supply in arid and semi-arid areas. The purpose of this study is to predict the impact of climate change on groundwater recharge in an…
Abstract
Purpose
Groundwater is an important source of water supply in arid and semi-arid areas. The purpose of this study is to predict the impact of climate change on groundwater recharge in an arid environment in Ilam Province, west of Iran.
Design/methodology/approach
A three-dimensional transient groundwater flow model (modular finite difference groundwater FLOW model: MODFLOW) was used to simulate the impacts of three climate scenarios (i.e. an average of a long-term rainfall, predicted rainfall in 2015-2030 and three years moving average rainfall) on groundwater recharge and groundwater levels. Various climate scenarios in Long Ashton Research Station Weather Generator were applied to predict weather data.
Findings
HadCM3 climatic model and A2 emission scenario were selected as the best methods for weather data generation. Based on the results of these models, annual precipitation will decrease by 3 per cent during 2015-2030. For three emission scenarios, i.e. an average of a long-term rainfall, predicted rainfall in 2015-2030 and three years moving average rainfall, precipitation in 2030 is estimated to be 265, 257 and 247 mm, respectively. For the studied aquifer, predicted recharge will decrease compared to recharge calculated based on the average of long-term rainfall.
Originality/value
The decline of groundwater level in the study area was 11.45 m during the past 24 years or 0.48 m/year. Annual groundwater depletion should increase to 0.75 m in the coming 16 years via climate change. Climate change adaptation policies in the basin should include changing the crop type, as well as water productivity and irrigation efficiency enhancement at the farm and regional scales.
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Ahmad Naderi, Leila Nasrolahi Vosta, Abolghasem Ebrahimi and Mohammad Reza Jalilvand
The exploration of performance determinants in social enterprises has gained increasing relevance among researchers and practitioners, particularly in rural tourism. The purpose…
Abstract
Purpose
The exploration of performance determinants in social enterprises has gained increasing relevance among researchers and practitioners, particularly in rural tourism. The purpose of this paper is to analyze the contributions of transformational leadership and social entrepreneurship to the performance of social enterprises in the context of rural tourism. Further, the mediating roles of social capital, creativity and social value were investigated.
Design/methodology/approach
Data were gathered through a survey of 168 employees of social enterprises operating in the rural tourism setting. Eight surveyors were sent out to conduct the survey. Data were analyzed by structural equation modeling (SEM) using AMOS 18.0.
Findings
The results of the SEM suggested that transformational leadership is positively associated with social value, social capital and performance of social enterprise. In addition, social entrepreneurship had a significant influence on social value, social capital and performance of social enterprise. Creativity and social value predicts the performance of social enterprise. Further, social capital was found to have a positive relationship with creativity. Finally, the mediating roles of social capital, creativity and social value were also confirmed. The findings thus highlight the power of the social value creation and social capital in the social enterprises operating in the rural destinations.
Social implications
The findings assert that social entrepreneurship and transformational leadership are key sources of social value creation, social capital and creativity in rural tourism context indicating the need for additional efforts on this kind of entrepreneurial activity. The findings can motivate policymakers to promote social entrepreneurship in rural tourism destinations as a means of stimulating bottom-up social capital and social value creation.
Originality/value
This study is among the first to examine the hypothesized relationships focusing on tourism social enterprises.
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This article examines the application of "resource dependency theory" to transnational corporations (TNCs) operating in host countries like Bangladesh to explain the relationship…
Abstract
This article examines the application of "resource dependency theory" to transnational corporations (TNCs) operating in host countries like Bangladesh to explain the relationship between the TNCs and Bangladesh. Data indicate that while the TNCs' participation in a third world host country is encouraged primarily for promoting its economic development, TNCs are mainly attracted by market size, purchasing capacities (determined mainly by GNP) of the population, and stable political condition of the country. Although examination of the application of resource dependency theory provides some insights into understanding the complicated relationship between TNCs and Bangladesh, several other factors, not explained by resource dependency theory, help explain the behavior of TNCs in a host country
Mohammad Gharipour, Ehsan Masoud, Jamal Esmaeilzadeh Vafaei and Fateme Jahani Sadatmahalle
The advancement of medical care during the late 19th century and the rising importance of public health led to the creation of a healthcare infrastructure in Iran in the early…
Abstract
Purpose
The advancement of medical care during the late 19th century and the rising importance of public health led to the creation of a healthcare infrastructure in Iran in the early decades of the 20th century. The study focuses on the formation of this infrastructure through the study of historical materials as well as the study of case studies built in the Gilan region in the north of Iran.
Design/methodology/approach
This paper begins with a review of medical, sociological and historical resources, then turns to field studies and interviews as methods to focus on the medical transformations in the Gilan region.
Findings
This study offers four key findings: First of all, most studies tend to focus more on traditional medicine in Iran than on the initiation and spread of modern medicine. Secondly, foreign physicians and missionaries played an influential role in shaping the culture of Iranian hospital care. Thirdly, the interactions with and influences coming from Iran’s northern neighbors in Gilan transformed the province into an educated, freedom-seeking society. And finally, in its early stages, hospital construction in Iran followed local architectural traditions.
Originality/value
In the case of Gilan, the core structures of urban hospitals were similar in their pavilion typology to those that had been common in Gilan for centuries.
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Zahra Fallah Ebrahimi, Chin Wei Chong and Reza Hosseini Rad
The aim of this paper is to evaluate the impact of total quality management (TQM) practices on role stressors in Iranian manufacturing SMEs in order to determine the relationship…
Abstract
Purpose
The aim of this paper is to evaluate the impact of total quality management (TQM) practices on role stressors in Iranian manufacturing SMEs in order to determine the relationship between the multidimensionality of TQM practices and role ambiguity, role conflict and role overload.
Design/methodology/approach
Questionnaires are administrated to 410 employees of 100 different manufacturing SMEs in Iran.
Findings
The results support important negative association among some of TQM practices (such as employee involvement, information analysis, process management, supplier management, strategic planning and customer focus) and role conflict, role ambiguity, role overload. By utilizing multiple regression analysis, information analysis, supplier management, employee involvement, process management, customer focus, strategic planning are found to have significant and negative relationship with role stressors. Leadership and human resource focus are found to have significant and positive relationship with role stressors.
Practical implications
This model is perfect for practical usage by SME managers to estimate the perceptions of role stressors of employees in TQM oriented firms. The findings recommend that manufacturing should look into ways of improving the major roles of TQM practices in order to decrease the negative role stressors of employees.
Originality/value
TQM practices emerge to be related to role stressors (role ambiguity, role conflict and role overload), attending to an obvious noticeable gap in the previous studies of TQM and the psychological welfare of employees.
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Artur Strzelecki and Mariia Rizun
This paper aims to consider the question of changes brought to consumers’ trust and security issues by the implementation of the General Data Protection Regulation (GDPR) in…
Abstract
Purpose
This paper aims to consider the question of changes brought to consumers’ trust and security issues by the implementation of the General Data Protection Regulation (GDPR) in electronic commerce.
Design/methodology/approach
Online shopping policies in Poland and Ukraine are compared from the perspective of four factors as follows: application of terms of service and privacy policy, usage of online payment systems, presence in price comparison engines and grade of secure sockets layer security certificates. Comparison is conducted within the framework of three research questions (complemented by eight hypotheses) set to reveal whether: policies of personal data protection and server security for online stores in both countries are the same; all online stores in both countries obey the existing e-commerce rules; e-commerce policies in the two countries differ significantly. The sample for analysis contains 40 Polish and 40 Ukrainian online stores, representing four industries, namely, electronics, entertainment, fashion and goods for children.
Findings
The research allowed to reveal major differences in the privacy policy of the two countries, caused, mainly, by the absence of GDPR in Ukraine. It also disclosed much stronger cooperation of online stores and price comparison engines in Poland compared to Ukraine. At the same time, research results allow to state that server security in both countries is on the same rather high level and that online stores use transparent and safe methods of online payment.
Research limitations/implications
This research opens a way to other, expanded observations which will include more countries and larger scopes of data. Its main limitation is that GDPR influence is only studied in two countries, not in all countries where it is implemented.
Originality/value
This research contributes from security and trust perspectives by analyzing the situation in two countries as follows: the EU member (Poland) and a non-EU country (Ukraine). The value of exploring the situation of Ukrainian e-commerce consists of understanding how online stores function without implementing the GDPR. Observation of shopbots application allows drawing an important conclusion of the necessity for online stores to cooperate with such services. It was also revealed that consumers’ trust in both countries depends a lot on the payment methods applied by an online store and on the ease of use of these methods.
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Meenal Arora, Jaya Gupta and Amit Mittal
This study aims to provide insight into consumer behavior regarding the use of food delivery apps when making purchases. To investigate the primary elements affecting users'…
Abstract
Purpose
This study aims to provide insight into consumer behavior regarding the use of food delivery apps when making purchases. To investigate the primary elements affecting users' intentions to use meal delivery applications, this study suggests an extension to the technology acceptance model through some contextual variable such as “various food choices (VFC),” “trust (TRR),” “perception of COVID-19-related risks (PCR)” and “convenience (CONV)” during the pandemic.
Design/methodology/approach
A cross-sectional data of 407 was collected in the Indian context. This research adopts the covariance-based structural modeling approach to test the hypotheses along with hierarchical regression to predict the efficiency of constructs.
Findings
Considering the outcomes, “perceived usefulness (PU)” was positively influenced by “perceived ease of use (PEOU),” “VFC” and “CONV.” In addition, the attitude (ATT) was positively impacted by “PU,” “TRR” and “PEOU.” Nevertheless, “PCR” negatively influenced ATT. In additional, this research illustrates the positive impact of ATT and PU on behavioral intention to use.
Originality/value
By confirming the technology acceptance model's capacity for explanation in relation to food delivery apps, this study adds to the body of knowledge. The primary focus of this study is on determining the direct impact of the identified determinants on the adoption of food delivery applications within the context of a pandemic situation in developing countries.