Search results
1 – 10 of over 134000Yifan Shi, Yuan Wang, Xiaozhou Liu and Ping Wang
Straightness measurement of rail weld joint is of essential importance to railway maintenance. Due to the lack of efficient measurement equipment, there has been limited in-depth…
Abstract
Purpose
Straightness measurement of rail weld joint is of essential importance to railway maintenance. Due to the lack of efficient measurement equipment, there has been limited in-depth research on rail weld joint with a 5-m wavelength range, leaving a significant knowledge gap in this field.
Design/methodology/approach
In this study, the authors used the well-established inertial reference method (IR-method), and the state-of-the-art multi-point chord reference method (MCR-method). Two methods have been applied in different types of rail straightness measurement trollies, respectively. These instruments were tested in a high-speed rail section within a certain region of China. The test results were ultimately validated through using traditional straightedge and feeler gauge methods as reference data to evaluate the rail weld joint straightness within the 5-m wavelength range.
Findings
The research reveals that IR-method and MCR-method produce reasonably similar measurement results for wavelengths below 1 m. However, MCR-method outperforms IR-method in terms of accuracy for wavelengths exceeding 3 m. Furthermore, it was observed that IR-method, while operating at a slower speed, carries the risk of derailing and is incapable of detecting rail weld joints and low joints within the track.
Originality/value
The research compare two methods’ measurement effects in a longer wavelength range and demonstrate the superiority of MCR-method.
Details
Keywords
Qing Wang, Peng Huang, Jiangxiong Li and Yinglin Ke
The purpose of this paper is to increase the measurement accuracy of assembly deviations of an inertial navigation system, a new evaluation and optimal method of assembly…
Abstract
Purpose
The purpose of this paper is to increase the measurement accuracy of assembly deviations of an inertial navigation system, a new evaluation and optimal method of assembly metrology system is proposed, which takes into account the uncertainty from laser tracker hardware and coordinate system transformation, and is based on the Monte Carlo method.
Design/methodology/approach
The uncertainty model of the laser tracker is established and its parameters are obtained from the known repeated test data by kriging interpolation and the least squares method. The errors of coordinate transformation are reduced by using a weighted point matching method, and the uncertainty of the transformation parameters is obtained based on the generalized inverse theory. The weighting coefficients of each reference point are optimized by the particle swarm optimization method according to the assembly requirements.
Findings
The experiment results show that measurement error and predicted results match well, and the assembly deviation uncertainty of large component is reduced by about 10 per cent compared with the singular value decomposition method.
Originality/value
This paper proposes a method to evaluate and eliminate the influence of random errors of the laser tracker during evaluation process of coordinate translation parameters and assembly deviations. The proposed method would be useful to improve the assembly measurement accuracy through less measurement times.
Details
Keywords
Juan Carlos Bou Llusar and César Camisón Zornoza
This paper verifies the adequacy of perceived quality measurement instruments by comparing the SERVPERF and EP methods. After a discussion of the differences between the two…
Abstract
This paper verifies the adequacy of perceived quality measurement instruments by comparing the SERVPERF and EP methods. After a discussion of the differences between the two methods, a quality perception measurement instrument for the company is developed and applied to a sample of ceramic company clients. The methods are compared by analyzing the multitrait‐multimethod matrix using the structural equation model methodology. Results indicate that SERVPERF has greater reliability, greater convergent and discriminant validity, explains variance more completely, and consequently introduces less bias.
Details
Keywords
THE improvement in the British standard of living is generally desired. Politicians have not only subscribed to that ideal but some of them have indicated the rate at which we…
Abstract
THE improvement in the British standard of living is generally desired. Politicians have not only subscribed to that ideal but some of them have indicated the rate at which we should advance. There are, however, certain trends in the country's economic life which must be reversed if we are to make any progress in that direction.
Shuanggao Li, Wenmin Chu and Xiang Huang
The measurement of aircraft barycenter is a verification of theoretical barycenter and is an important step of aircraft development. In the traditional measurement method of…
Abstract
Purpose
The measurement of aircraft barycenter is a verification of theoretical barycenter and is an important step of aircraft development. In the traditional measurement method of aircraft barycenter, the posture of the aircraft needs to be adjusted manually and is measured by optical instruments. The efficiency of posture adjustment depends on the proficiency of workers, and the accuracy of measurement is not high. In view of these problems of the current barycenter measurement method, this paper aims to propose an aircraft barycenter measurement method based on multi-posture.
Design/methodology/approach
In this method, the numerical control locator is used as a supporting part to fix and adjust the aircraft, and the calculation model of aircraft barycenter is established according to the principle of rigid body rotation and the principle of moment balance. Then, the influence of the main error sources on the measurement accuracy of aircraft barycenter is analyzed by Monte Carlo simulation, and the measurement accuracy is compared with that of the barycenter measurement method based on horizontal posture. Finally, the experiment platform of barycenter measurement was built in the laboratory and the experiments were carried out.
Findings
The experimental results show that the barycenter measurement method proposed in this paper has obvious advantages in measurement accuracy and efficiency compared with the traditional method.
Originality/value
This method can be used to measure the barycenter of different types of aircraft quickly and automatically.
Details
Keywords
Aki Jääskeläinen and Erkki Uusi‐Rauva
This study aims to identify means to overcome some of the current problems in public service productivity measurement. The objective is to develop a new method for measuring…
Abstract
Purpose
This study aims to identify means to overcome some of the current problems in public service productivity measurement. The objective is to develop a new method for measuring productivity in large public organizations.
Design/methodology/approach
The research is carried out as a constructive case study in the City of Helsinki, Finland. Interviews are used in order to identify practical requirements for measurement. The measurement data from around 200 units is used in testing the method.
Findings
The new method applies an approach proposed in the literature. It aggregates measurement information from component measures used at the operative level. Based on test calculations and evaluation it is argued that the new method is managerially more relevant than a conventional method.
Research limitations/implications
This study tested the method only to a limited extent. It is necessary to gain more understanding by applying the method in different organizations, and by using longer time periods.
Practical implications
Current productivity measures of public services have been criticized for providing information that lacks managerial relevance. The method described in this study aims to improve relevance in two ways. It enables the gathering of more detailed measurement information from the operative levels of large organizations. In addition, it facilitates the use of different measurement methods in different service providing departments and units.
Originality/value
Many of the existing studies examine productivity measurement at the macro‐level. This study presents a measurement method that is a step forward in developing more sophisticated measurement systems in public organizations. The study also describes and highlights the role of component productivity measurement at the operative level.
Details
Keywords
Xindang He, Run Zhou, Zheyuan Liu, Suliang Yang, Ke Chen and Lei Li
The purpose of this paper is to provide a comprehensive review of a non-contact full-field optical measurement technique known as digital image correlation (DIC).
Abstract
Purpose
The purpose of this paper is to provide a comprehensive review of a non-contact full-field optical measurement technique known as digital image correlation (DIC).
Design/methodology/approach
The approach of this review paper is to introduce the research pertaining to DIC. It comprehensively covers crucial facets including its principles, historical development, core challenges, current research status and practical applications. Additionally, it delves into unresolved issues and outlines future research objectives.
Findings
The findings of this review encompass essential aspects of DIC, including core issues like the subpixel registration algorithm, camera calibration, measurement of surface deformation in 3D complex structures and applications in ultra-high-temperature settings. Additionally, the review presents the prevailing strategies for addressing these challenges, the most recent advancements in DIC applications across quasi-static, dynamic, ultra-high-temperature, large-scale and micro-scale engineering domains, along with key directions for future research endeavors.
Originality/value
This review holds a substantial value as it furnishes a comprehensive and in-depth introduction to DIC, while also spotlighting its prospective applications.
Details
Keywords
The purpose of this paper is to present a new method of measuring thermal resistance of power light-emitting diodes (LEDs). Properties of power LEDs strongly depend on their…
Abstract
Purpose
The purpose of this paper is to present a new method of measuring thermal resistance of power light-emitting diodes (LEDs). Properties of power LEDs strongly depend on their internal temperature. The value of this temperature depends on the cooling conditions characterized by thermal resistance.
Design/methodology/approach
The new method of measuring the value of this parameter belongs to the group of electric methods. In this method, the problem of estimating the value of electrical power converted into light is solved. By comparing the values of the case temperature obtained for the LED operating in the forward mode and the reverse-breakdown mode, the thermal power is estimated. On the basis of the measured value of the thermally sensitive parameter (the LED forward voltage) and the estimated value of the thermal power, thermal resistance is calculated.
Findings
The elaborated method was used to measure thermal resistance of the selected types of power LEDs operating at different cooling conditions. The correctness of the elaborated measurement method was proved by comparing the results of measurements obtained with the use of the new method and the infrared method.
Research limitations/implications
On the basis of the obtained results of measurements and the catalog data of the tested diodes, the dependence of the measurement error of thermal resistance of the LED on its luminous efficiency is discussed.
Originality/value
The new measurement method is easy to use and more accurate than the classical method of thermal resistance measurement of the diode.
Details
Keywords
Ammar Saeed Mohammed Moohialdin, Fiona Lamari, Marc Miska and Bambang Trigunarsyah
The purpose of this paper shows the effect of hot and humid weather conditions (HHWCs) on workers that has resulted in considerable loss in the construction industry, especially…
Abstract
Purpose
The purpose of this paper shows the effect of hot and humid weather conditions (HHWCs) on workers that has resulted in considerable loss in the construction industry, especially during the hottest periods due to decline in worker productivity (WP). Until the last few decades, there is very limited research on construction WP in HHWCs. Nevertheless, these studies have sparked interests on seeking for the most appropriate methods to assess the impact of HHWCs on construction workers.
Design/methodology/approach
This paper begins by reviewing the current measuring methods on WP in HHWCs, follows by presenting the potential impact of HHWCs on WP. The paper highlights the methodological deficiencies, which consequently provides a platform for scholars and practitioners to direct future research to resolve the significant productivity loss due to global warming. This paper highlights the need to identify the limitations and advantages of the current methods to formulate a framework of new approaches to measure the WP in HHWCs.
Findings
Results show that the methods used in providing real-time response on the effects of HHWCs on WP in construction at project, task and crew levels are limited. An integration of nonintrusive real-time monitoring system and local weather measurement with real-time data synchronisation and analysis is required to produce suitable information to determine worker health- and safety-related decisions in HHWCs.
Originality/value
The comprehensive literature review makes an original contribution to WP measurements filed in HHWCs in the construction industry. Results of this review provide researchers and practitioners with an insight into challenges associated with the measurements methods and solving practical site measurements issues. The findings will also enable the researchers and practitioners to bridge the identified research gaps in this research field and enhance the ability to provide accurate measures in HHWCs. The proposed research framework may promote potential improvements in the productivity measurements methods, which support researchers and practitioners in developing new innovative methods in HHWCs with the integration of the most recent monitoring technologies.
Details
Keywords
This paper (which is the first of three) explains how to undertake an anthropometric survey, first, by reviewing previous surveys and size charts to select which measurements to…
Abstract
This paper (which is the first of three) explains how to undertake an anthropometric survey, first, by reviewing previous surveys and size charts to select which measurements to take and the appropriate equipment. The sample of persons to be measured had to be determined, the main constraint being the availability of time. The selection of measurements was made for the end use of constructing garment patterns by both direct and proportional measurement systems. ‘Check’ measurements for accuracy were also built into the procedure. Finally 10 measurements were selected and 100 young women between the ages of 18 and 28 years were measured. It is concluded that measuring the human body is not easy. Hopefully new technology will improve this task. Twenty more body measurements will be brought into use, which will be explained in Part 2.
Details