Baoling Cui, Xiaodi Li, Kun Rao, Xiaoqi Jia and Xiaolin Nie
Radial vibration of horizontal centrifugal pump has a close association with radial exciting forces. The purpose of this paper is to analyze the unsteady radial force in…
Abstract
Purpose
Radial vibration of horizontal centrifugal pump has a close association with radial exciting forces. The purpose of this paper is to analyze the unsteady radial force in multistage centrifugal pump with double volute in detail and investigate the relevance of static pressure, radial force and radial vibration.
Design/methodology/approach
The unsteady numerical simulation with realizable k-ε turbulence model was carried out for a multistage centrifugal pump with double volute using computational fluid dynamics codes Fluent. The performance tests were conducted by use of a closed loop system and performance curves from numerical simulation agree with that of experiment. Vibration tests were carried out by vibration probes instrumented on the bearing cover of pump near no-driven end. Fast Fourier transform was used to obtain the frequency components of radial forces on the impellers from numerical simulation, which are compared with ones of radial vibration from experiment in Y and Z direction. And the static pressure distributions in the impeller were analyzed under different flow rates.
Findings
The symmetrical double volute can effectively balance radial forces. The maximum radial force and vibration velocity appear at 0.6 Q among the three flow rates 0.6 Q, Q and 1.2 Q. The frequencies corresponding to relatively large amplitude of vibration velocities and radial forces on the impellers in Y direction are blade passing frequency of the impellers. Blade passing frequency of first-stage impeller and shaft frequency are predominating in Z direction. It indicates that the radial vibration of centrifugal pump is closely related to the unsteady radial force.
Originality/value
The unsteady radial forces of the impeller in multistage centrifugal pump with double volute were comprehensively analyzed. The radial forces should be considered to balance during the design of multistage centrifugal pump.
Details
Keywords
Kevin Fagan, Xiaodi Li, Ermengarde Jabir and Victor Calanog
The authors take a historical perspective and compare office market performance metrics and CMBS loan delinquency rates over the past two years with previous downturns.
Abstract
Purpose
The authors take a historical perspective and compare office market performance metrics and CMBS loan delinquency rates over the past two years with previous downturns.
Design/methodology/approach
What will happen to the office sector in the post-pandemic era? we examine this question from three perspectives. First, the authors discuss the (short-term) risk of commercial real estate investment with high inflation and rising interest rates. If investors want to use CRE as an inflationary hedge, the cash flow must increase enough to counteract growing cap rates given rising interest rates.
Findings
As it turns out, the COVID-19 recession has been notably innocuous. Third, the authors focus on medical office space – an emerging investment option for the office sector.
Practical implications
The authors remain somewhat positive (or at least less downbeat) about the future of the office market based on the data they reviewed.
Originality/value
The office market is experiencing an odyssey rather than an exodus, at least in the short run. However, the authors remain cautious and they are monitoring key signs, prepared for the possibility of (r)evolutionary change in the office sector.
Details
Keywords
Xiaodi Sun, Li Ge and Charles Marvil
This study aims to compare customers’ perceived importance of various post-COVID-19 recovery strategies (i.e. sanitary practices, discounts, menu modification and marketing…
Abstract
Purpose
This study aims to compare customers’ perceived importance of various post-COVID-19 recovery strategies (i.e. sanitary practices, discounts, menu modification and marketing strategies) adopted by independent full-service restaurants (casual dining versus upscale/fine dining) using the salience theory. It also assesses the associations between customers’ perceptions and their restaurant spending patterns.
Design/methodology/approach
An online survey was administered to assess 657 US adult participants’ restaurant spending behaviors at different stages of the COVID-19 pandemic using recall questions. Higher-spending versus lower-spending participants’ perceived importance of restaurant recovery strategies were compared in the casual dining versus upscale/fine dining contexts.
Findings
Amid the COVID-19 pandemic, sanitary practices were the most important factor in participants’ restaurant choices, and it was more important for independent casual dining restaurants than for upscale/fine dining restaurants. No significant difference was found in participants’ perceived importance of sanitary practices across different geographic regions. Higher-spending diners (HSD) perceived almost every restaurant recovery strategy as important. Lower-spending diners (LSD) only considered sanitary practices as important.
Practical implications
This study identified important strategies that restaurant operators and public health officials can adopt to help full-service restaurants recover from pandemic losses.
Originality/value
This study differs from previous consumer choice studies; in that it compared HSD with LSD regarding their perceived importance of various restaurant recovery strategies. This study also provides new insights for understanding the salience theory of choice under the impact of COVID-19.
Details
Keywords
Nava Cohen and Xiaodi Zhu
This paper aims to examine the consistency between firms’ stakeholder-friendly responses to the COVID-19 pandemic and their environmental, social and governance (ESG) ratings…
Abstract
Purpose
This paper aims to examine the consistency between firms’ stakeholder-friendly responses to the COVID-19 pandemic and their environmental, social and governance (ESG) ratings. Consistent firms are those with high prior ESG ratings that actively support stakeholders during the COVID-19 crisis.
Design/methodology/approach
The authors use data from JUST Capital, which tracks Russell 1000 firms’ actions in response to the pandemic, to examine the relationship between pre-pandemic ESG ratings and their COVID responses towards employees, customers and communities. The authors also analyse the impact of firms’ consistency between pre-pandemic ESG ratings and stakeholder-friendly COVID responses on ESG ratings and stock returns.
Findings
This study finds that firms with higher pre-pandemic ESG ratings are more likely to support their stakeholders during the pandemic. The authors also find that firms with high ESG ratings before the pandemic experience a decline in their ESG ratings if they do not actively support their communities during the COVID-19 crisis, although insufficient employee/customer support does not impact their ESG ratings. Finally, the authors find that firms with higher pre-pandemic ESG ratings that continue to uphold their ESG commitments through community assistance during the pandemic achieve higher stock returns compared to inconsistent firms.
Practical implications
The results reveal gaps in how comprehensively ESG agencies assess firms’ crisis responses, highlighting areas for rating improvements. The findings contribute to sustainable development by revealing the importance of firms upholding their ESG commitments during crises to maintain stakeholder trust and drive long-term value creation.
Social implications
The findings underscore the need for responsive, transparent ESG rating processes to support the integration of sustainability considerations into corporate practices and investment decisions, particularly during evolving societal expectations during crises.
Originality/value
To the best of the authors’ knowledge, this study is the first to investigate how pre-pandemic ESG ratings explain firms’ stakeholder-friendly responses during the COVID-19 pandemic and analyse the integration of these responses and pandemic risks into ESG ratings during the crisis.
Details
Keywords
Xiaodi Xu, Shanchao Sun, Yang Fei, Liubin Niu, Xinyu Tian, Zaitian Ke, Peng Dai and Zhiming Liang
This article aims to predict the rapid track geometry change in the short term with a higher detection frequency, and realize the monitoring and maintenance of the railway state.
Abstract
Purpose
This article aims to predict the rapid track geometry change in the short term with a higher detection frequency, and realize the monitoring and maintenance of the railway state.
Design/methodology/approach
Firstly, the ABA data needs to be filtered to remove the DC component to reduce the drift due to integration. Secondly, the quadratic integration in frequency domain for concern components of the vertical and lateral ABA needs to be done. Thirdly, the displacement in lateral of the wheelset to rail needs to be calculated. Then the track alignment irregularity needs to be calculated by the integration of lateral ABA and the lateral displacement of the wheelset to rail.
Findings
By comparing with a commercial track geometry measurement system, the high-speed railway application results in different conditions, after removal of the influence of LDWR, identified that the proposed method can produce a satisfactory result.
Originality/value
This article helps realize detection of track irregularity on operating vehicle, reduce equipment production, installation and maintenance costs and improve detection density.
Details
Keywords
The aim of this paper is to argue for the values of familial caring and relationships in addition to the provision of social media technology during the COVID-19 pandemic in Hong…
Abstract
Purpose
The aim of this paper is to argue for the values of familial caring and relationships in addition to the provision of social media technology during the COVID-19 pandemic in Hong Kong.
Design/methodology/approach
The discussion of this paper has adopted an inter-disciplinary approach by integrating health care system and psychological analysis, based on cultural philosophical argument through the hermeneutic approach of classical texts and critical analysis.
Findings
The COVID-19 pandemic has exposed the dilemma between the public health measures for COVID-19 and sustaining elderly social psychological health through familial connection. From a Confucian perspective, the practice of filial piety (xiao, 孝), which demands taking care of parents, is essential for one’s moral formation, and for one’s becoming a virtuous (ren, 仁) person. The necessity of taking care of elderly parents by adult children is not something that can be explained in terms of consequentialism. Indeed, the rising trend of instrumental rationality seems to weaken rather than strengthen the sense of filial obligation. In the face of the COVID-19 pandemic which tends to separate connections between family members, the author argues that we should emphasize the values of familial caring and relationship because it enhances the elderly’s characteristic of resilience.
Originality/value
This paper shows that while social media technology has mitigated the negative effect of social distancing, such online relationships should never replace the bodily connections between the elderly and their family members from a Confucian perspective.
Details
Keywords
Okan Sirin, Murat Gunduz and Mohammed E. Shamiyeh
Pavement is one of the main elements of the roads network. It is extremely essential to study and understand the factors affecting its performance and highlight the most important…
Abstract
Purpose
Pavement is one of the main elements of the roads network. It is extremely essential to study and understand the factors affecting its performance and highlight the most important ones for decision-makers and pavement experts to consider during the design, construction and maintenance stages. The purpose of this paper was to identify the factors affecting pavement performance and rank them according to their importance using Analytic Hierarchy Process (AHP) for decision-makers and pavement experts to consider during the design, construction and maintenance stages.
Design/methodology/approach
A survey was developed considering 29 factors found in the literature that affect pavement performance. The survey was sent to pavement professionals in Qatar to rate their perception of factors affecting pavement performance to enhance roads' sustainability. 205 responses were collected and analyzed using AHP.
Findings
The findings indicate that the factor “unconsidered heavy vehicles volume” is the most critical factor that affects pavement performance. The second most critical factor affecting the pavement performance is the “low asphalt content” due to escalating binder aging, reducing fatigue life of the pavement and decreasing the durability of roads. The third and fourth factors are “poor mechanical and thermal properties” and “unexpected high traffic volume,” respectively. These two factors are strongly attached to the first and second factors since the traffic volume affects the pavement performance less but similar to the heavy vehicles and a mix with poor mechanical and thermal properties is related indirectly to the asphalt content in the mix.
Originality/value
The research provides help for decision-makers in the construction industry to improve the performance of pavements using a multi-criteria decision-making tool. This paper's outcome would help the pavement management professionals in the construction industry to improve pavement performance and management, increase the pavement's life cycle and reduce maintenance costs.
Details
Keywords
Abstract
Purpose
The purpose of this paper is to study the multi-objective optimization design method of high-power high-frequency magnetic-resonance air-core transformer (ACT).
Design/methodology/approach
First, this paper studies the interleaved winding technology, the process of modeling and simulation, the calculation method of high-frequency loss of Litz wire and the design of magnetic shielding in detail. Second, the multi-objective optimization design process of high-frequency magnetic-resonance ACT is established by parametric scanning method and orthogonal experiment method.
Findings
An ACT model of 2 kV/100 kW/81.34 kHz was designed. The efficiency, weight power density and volume power density are 99.61%, 21.6 kW/kg and 5.1 kW/kg, respectively. Finally, the multi-physical field coupling simulation method is used to calculate the port excitation voltages and currents and temperature field of ACT. The maximum temperature of the ACT is 95.5 °C, which meets the design requirements.
Originality/value
The above research provides guidance and basis for the optimization design of high-power high-frequency magnetic-resonance ACT.