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Article
Publication date: 17 July 2018

Kai Yang, Mingli Jiao, Sifan Wang, Yuanyuan Yu, Quan Diao and Jian Cao

The purpose of this paper is to investigate thermoregulation properties of different composite phase change materials (PCMs), which could be used in the high temperature…

Abstract

Purpose

The purpose of this paper is to investigate thermoregulation properties of different composite phase change materials (PCMs), which could be used in the high temperature environmental conditions to protect human body against the extra heat flow.

Design/methodology/approach

Three kinds of composite PCM samples were prepared using the selected pure PCMs, including n-hexadecane, n-octadecane and n-eicosane. The DSC experiment was performed to get the samples’ phase change temperature range and enthalpy. The simulated high temperature experiments were performed using human arms in three different high temperature conditions (40°C, 45°C, 50°C), and the skin temperature variation curves varying with time were obtained. Then a comprehensive index TGP was introduced from the curves and calculated to evaluate the thermoregulation properties of different composite PCM samples comprehensively.

Findings

Results show that the composite PCM samples could provide much help to the high temperature human body. It could decrease the skin temperature quickly in a short time and it will not cause the over-cooling phenomenon. Comparing with other two composite PCM samples, the thermoregulation properties of the n-hexadecane and n-eicosane composite PCM is the best.

Originality/value

Using the n-hexadecane and n-eicosane composite PCM may provide people with better protection against the high temperature conditions, which is significative for the manufacture of functional thermoregulating textiles, garments or equipments.

Details

International Journal of Clothing Science and Technology, vol. 30 no. 4
Type: Research Article
ISSN: 0955-6222

Keywords

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Book part
Publication date: 13 August 2018

Hsin-yi (Shirley) Hsieh, Jian Cao and Mark Kohlbeck

Purpose – We investigate the impact of CEO turnover on performance and accounting-based outcomes following major business restructurings.Design/Methodology/Approach – We

Abstract

Purpose – We investigate the impact of CEO turnover on performance and accounting-based outcomes following major business restructurings.

Design/Methodology/Approach – We analyze a sample of 217 major operational restructurings during the period 1999–2007 using regressions and other statistical tests.

Findings – We document significant improvements in postrestructuring operating and investment efficiencies with little differentiation between restructurings that involve a change in CEO and those that involve continuing CEOs. However, we find evidence of lower accounting quality for the continuing CEO firms. First, restructuring charges of CEO turnover firms are associated with lower current period unexpected core earnings and higher future period unexpected core earnings (lower levels of classification shifting). Second, CEO turnover firms have a significantly lower percentage of (i) restructuring charge reversals and (ii) prereversal shortfalls (in meeting analyst forecast estimates) followed by reversals (suggesting lower levels of subsequent earnings management). Therefore, turnover CEOs are less likely to manipulate restructuring charges to mask true economic performance than continuing CEOs. Overall, our evidence suggests continuing CEOs undertake less substantial restructurings, while opportunistically reporting similar charges and performance improvements, consistent with attempts to pool with new CEO hires to keep their jobs.

Originality/Value – Overall, our results highlight the key economic role played by top corporate managers in major business restructurings, suggesting that CEO turnover leads to both real changes in managerial actions and altered reporting incentives.

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Article
Publication date: 10 April 2009

Hongxia Tong, Jian Cao, ShenSheng Zhang and Yujie Mou

This paper aims to define an extended QoS model to accurately describe the quality of web service in the open distributed environment and propose a fuzzy evaluation…

Abstract

Purpose

This paper aims to define an extended QoS model to accurately describe the quality of web service in the open distributed environment and propose a fuzzy evaluation approach for services selection based on the extended QoS model.

Design/methodology/approach

The extended QoS model classifies the quality criteria of web service as five composite quality criteria, and each composite quality criterion is composed by one or more sub‐quality criteria. Considering the multiple forms of representation for the quality criteria and different types of quality value could not be compared directly, a scaling fuzzy measure for quality criteria is introduced. Based on the scaling fuzzy measure of the quality criteria, a fuzzy synthetic evaluation system for services selection is proposed.

Findings

The quality of web service has multiple facets and multiple forms of representation. The fuzzy synthetic evaluation system can deal well with the fuzzy and implicit concepts about quality evaluations and provides higher expressive force and adaptability.

Research limitations/implications

The quality of service in this paper is static preset.

Originality/value

The extended QoS model and the synthetic fuzzy evaluation system cover the shortage of the related researches and lay the foundations for QoS‐oriented service description and services selection.

Details

Kybernetes, vol. 38 no. 3/4
Type: Research Article
ISSN: 0368-492X

Keywords

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Book part
Publication date: 13 August 2018

Abstract

Details

Advances in Management Accounting
Type: Book
ISBN: 978-1-78756-440-4

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Article
Publication date: 8 October 2019

Rui Wang, Haiou Zhang, Wang Gui-Lan and Xushan Zhao

The wire and arc additive manufacturing (WAAM) is a promising technology, but the parts are mostly manufactured on the plane and along the vertical direction. The purpose…

Abstract

Purpose

The wire and arc additive manufacturing (WAAM) is a promising technology, but the parts are mostly manufactured on the plane and along the vertical direction. The purpose of this paper is to propose a cylindrical slicing and manufacturing method.

Design/methodology/approach

For revolved parts, e.g. blades of a propeller, instead of planes, a series of cylindrical surfaces intersect with the STL model of the part. The generated slicing layers lie on the cylindrical surface, and then these spatial contours are unfolded onto the plane by the use of the cylindrical coordinate system. A deposition system based on an NC machine is established to examine deposition paths. The temperature and stress of part of two deposition orders are analyzed using the finite element method.

Findings

The scan parallel path and contour offset path are not suitable to fabricate blades directly. The hybrid of two types of paths and the hybrid of skeleton and contour offset paths are capable of forming blades without gaps. Deposition symmetrically can decrease the deformation of the propeller.

Originality/value

The slicing algorithm is simply implemented and practicable for any parts. The recognition of gaps and supplementary skeleton path can guarantee the full deposition of contour offset paths.

Details

Rapid Prototyping Journal, vol. 26 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 9 April 2018

Bin Shi, Jian Hua Guo, Xing An Cao, En Zhu Hu and Kun Hong Hu

This paper aims to explore the effects of mineral diesel fuel carbon soot (MCS) and biodiesel carbon soot (BCS) on the lubrication of polyalphaolefin (PAO) and diesel fuels.

Abstract

Purpose

This paper aims to explore the effects of mineral diesel fuel carbon soot (MCS) and biodiesel carbon soot (BCS) on the lubrication of polyalphaolefin (PAO) and diesel fuels.

Design/methodology/approach

Two styles of carbon soot were prepared from the natural combustion of mineral diesel fuel oil (MDO) and biodiesel oil (BDO). Tribological tests were conducted on a high-frequency reciprocating rig. Friction surfaces were characterized using three-dimensional laser scanning confocal microscopy and Raman spectroscopy.

Findings

The addition of MCS and BCS to PAO could reduce friction in most cases. MCS had a negligible effect on the wear for contents not exceeding 1.0 per cent. By contrast, BCS exhibited a considerable negative influence on the wear resistance even at low contents. For diesel fuels, MCS reduced both friction and wear, whereas BCS substantially deteriorated the lubrication of BDO. MCS formed a Fe3O4/C composite lubricating film on the friction surface. BCS also entered the contact region, but it did not form an effective Fe3O4/C composite lubricating film.

Originality/value

This work compared MDO and BDO from a different perspective, i.e. the effects of their combustion carbon soot on the lubrication of lubricating oil and fuel oil. The significant negative effect of BCS on the lubrication of lubricating oil and BDO is a problem that could occur in the industrial application of BDO.

Details

Industrial Lubrication and Tribology, vol. 70 no. 3
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 2 November 2017

Jiliang Mu, Zhang Qu, Zongmin Ma, Shaowen Zhang, Yunbo Shi, Jian Gao, Xiaoming Zhang, Huiliang Cao, li Qin, Jun Liu and Yanjun Li

This study aims to fabricate and manipulate ensemble spin of negative nitrogen-vacancy (NV) centres optimally for future solid atomic magnetometers/gyroscope. Parameters…

Abstract

Purpose

This study aims to fabricate and manipulate ensemble spin of negative nitrogen-vacancy (NV) centres optimally for future solid atomic magnetometers/gyroscope. Parameters for sample preparation most related to magnetometers/gyroscope are, in particular, the concentration and homogeneity of the NV centres, the parameters’ microwave antenna of resonance frequency and the strength of the microwave on NV centres. Besides, the abundance of other impurities such as neutral NV centres (NV0) and substitutional nitrogen in the lattice also plays a critical role in magnetic sensing.

Design/methodology/approach

The authors succeeded in fabricating the assembly of NV centres in diamond and they determined its concentration of (2-3) × 1016 cm−3 with irradiation followed by annealing under a high temperature condition. They explored a novel magnetic resonance approach to detect the weak magnetic fields that takes advantage of the solid-state electron ensemble spin of NV centres in diamond. In particular, the authors set up a magnetic sensor on the basis of the assembly of NV centres. They succeeded in fabricating the assembly of NV centres in diamond and determined its concentration. They also clarified the magnetic field intensity measured at different positions along the antenna with different lengths, and they found the optimal position where the signal of the magnetic field reaches the maximum.

Findings

The authors mainly reported preparation, initialization, manipulation and measurement of the ensemble spin of the NV centres in diamond using optical excitation and microwave radiation methods with variation of the external magnetic field. They determined the optimal parameters of irradiation and annealing to generate the ensemble NV centres, and a concentration of NV centres as high as 1016 cm−3 in diamond was obtained. In addition, they found that sensitivity of the magnetometer using this method can reach as low as 5.22 µT/Hz currently.

Practical implications

This research can shed light on the development of an atomic magnetometer and a gyroscope on the basis of the ensemble spin of NV centres in diamond.

Social implications

High concentration spin of NV in diamond is one of the advantages compared with that of the atomic vapor cells, because it can obtain a higher concentration. When increasing the spin concentration, the spin signal is easy to detect, and macro-atomic spin magnetometer become possible. This research is the first step for solid atomic magnetometers with high spin density and high sensitivity potentially with further optimization. It has a wide range of applications from fundamental physics tests, sensor applications and navigation to detection of NMR signals.

Originality/value

As has been pointed out, in this research, the authors mainly worked on fabricating NV centres with high concentration (1015-1016 cm−3) in diamond by using optimal irradiation and annealing processes, and they quantitatively defined the NV concentration, which is important for the design of higher concentration processes in the magnetometer and gyroscope. Until now, few groups can directly define the NV concentration. Besides, the authors optimized the microwave antenna parameters experimentally and explored the dependence between the splitting of the magnetic resonance and the magnetic fields, which dictated the minimum detectable magnetic field.

Details

Sensor Review, vol. 37 no. 4
Type: Research Article
ISSN: 0260-2288

Keywords

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Article
Publication date: 7 March 2016

Jian-Xin Shen, Shun Cai, Jian Yuan, Shuai Cao and Cen-Wei Shi

The purpose of this paper is to evaluate the cogging torque in a surface-mounted permanent magnet (SPM) machine with both uniformly and non-uniformly segmented stator…

Abstract

Purpose

The purpose of this paper is to evaluate the cogging torque in a surface-mounted permanent magnet (SPM) machine with both uniformly and non-uniformly segmented stator cores and to find out the optimal solution of stator core segmenting.

Design/methodology/approach

The cogging torque with segmented stators is synthesized from a single slot model, and analytical prediction is given to analyze the cogging torque with both uniformly and non-uniformly segmented stators. Finite element method (FEM) is used to figure out the electromagnetic field and validate the analytical prediction. Moreover, models with various shapes and positions of connecting tongues between the stator core segments are explored to achieve the optimal design.

Findings

The cogging torque is found to be greatly related to the number of segments and the electrical angle between adjacent additional air gaps caused by the tolerance of stator segments. Different shapes of the connecting tongues are tested and proved to be of great importance to the flux density, both radial and tangential, and therefore affect the cogging torque. Finally, position of the connecting tongues is perceived to have little influence on the performance of machine.

Practical/implications

By utilizing analytical prediction and FEM calculation, the optimal solution is discussed to minimize the cogging torque in the SPM machine from the perspective of the stator core segmentation.

Originality/value

This paper establishes formula of cogging torque with segmented stators and predicts the variation of cogging torque with analytical method. Besides, different combinations of segments are compared and measures to reduce the cogging torque produced by the segmentation are proposed.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 35 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 1 December 2020

Camillo Lento and Wing Him Yeung

This study aims to explore the audit quality supplied by the Big 4, large indigenous Chinese (LIC) and five largest second-tier international network (Tier 2) audit firms…

Abstract

Purpose

This study aims to explore the audit quality supplied by the Big 4, large indigenous Chinese (LIC) and five largest second-tier international network (Tier 2) audit firms in China during the second phase of their audit market development.

Design/methodology/approach

Ordinary least squares regression is used on an archival sample of firm-year observations. Endogeneity and self-selection bias are addressed by creating a propensity score matched sample and using two-stage regression with the inverse Mills’ ratio.

Findings

Strong evidence is found for higher levels of actual audit quality for the Big 4 relative to both LIC and Tier 2 audit firms. Weak evidence is found regarding the audit quality superiority of Tier 2 relative to LIC audit firms. Furthermore, the actual audit quality differential between the Big 4 relative to the LIC and Tier 2 firms widens after adopting International Financial Reporting Standards, which is contrary to the intention of Chinese regulators.

Originality/value

To the best of the authors’ knowledge, this is the first known empirical study to trisect Big N and non-Big N audit firm proxies into the Big 4, LIC and Tier 2. Currently, only qualitative studies have fully appreciated the unique regulatory roles of these three firm structures in developing China’s audit market, which reflect tensions between reliance on foreign expertise and self-determination. In addition, this study adds to the ongoing global dialogue on Tier 2 as an alternative to the Big 4 and the benefits of international accounting network membership.

Details

Managerial Auditing Journal, vol. 36 no. 1
Type: Research Article
ISSN: 0268-6902

Keywords

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Article
Publication date: 22 December 2020

Lin Xiao, Ting Pan, Jian Mou and Lihua Huang

The purpose of this paper is to build a comprehensive structural model to demonstrate the interrelationships of factors influencing social networking service (SNS) fatigue…

Abstract

Purpose

The purpose of this paper is to build a comprehensive structural model to demonstrate the interrelationships of factors influencing social networking service (SNS) fatigue and to identify the varying degrees of influence.

Design/methodology/approach

A total of 14 factors influencing SNS fatigue are identified through an extensive literature review. Interpretive structural modeling (ISM) and Matrice d'Impacts Croisés Multiplication Appliqué à un Classement (MICMAC) analysis are employed to build a hierarchical model and classify these factors into four clusters.

Findings

The results revealed that ubiquitous connectivity and immediacy of feedback are key factors contributing to SNS fatigue through their strong influence on other factors. Privacy concern, impression management concern and work–life conflict lead directly to SNS fatigue. In contrast, system feature overload and system pace of change are relatively insignificant in generating SNS fatigue.

Originality/value

This study represents an initial step toward comprehensively understanding the interrelationships among the factors leading to SNS fatigue and reveals how determinants of SNS fatigue are hierarchically organized, thus extending existing research on SNS fatigue. It also provides logical consistency in the ISM-based model for SNS fatigue by grouping identified factors into dependent and independent categories. Moreover, it extends the applicability of the integration of the ISM and MICMAC approaches to the phenomenon of SNS fatigue.

Details

Information Technology & People, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0959-3845

Keywords

1 – 10 of 192