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Article
Publication date: 18 April 2016

Hao Wen, Jian Gao and Xin Chen

As manufacturing technology has developed, digital models from advanced measuring devices have been widely used in manufacturing sectors. To speed up the production cycle and…

Abstract

Purpose

As manufacturing technology has developed, digital models from advanced measuring devices have been widely used in manufacturing sectors. To speed up the production cycle and reduce extra errors introduced in surface reconstruction processes, directly machining digital models in the polygonal stereolithographyformat has been considered as an effective approach in rapid digital manufacturing. In machining processes, Cutter Location (CL) data for numerical control (NC) machining is generated usually from an offset model. This model is created by offsetting each vertex of the original model along its vertex vector. However, this method has the drawback of overcut to the offset model. The purpose of this paper is to solve the overcut problem through an error compensation algorithm to the vertex offset model.

Design/methodology/approach

Based on the analysis of the vertex offset method and the offset model generated, the authors developed and implemented an error compensation method to correct the offset models and generated the accurate CL data for the subsequent machining process. This error compensation method is verified through three polygonal models and the tool paths generated were used for a real part machining.

Findings

Based on the analysis of the vertex offset method and the offset model generated, the authors developed an error compensation method to correct the offset models and generated the accurate CL data for the subsequent machining process. The developed error compensation algorithm can effectively solve the overcut drawback of the vertex offset method.

Research limitations/implications

The error compensation method to the vertex offset model is used for generating the CL data with the using of a ball-end cutter.

Practical implications

On the study of CL data generation for a STL model, most of the current studies are focused on the determination of the offset vectors of the vertexes. The offset distance is usually fixed to the radius of the cutter used. Thus, the overcut problem to the offset model is inevitable and has not been much studied. The authors propose an effective approach to compensate the insufficient distance of the offset vertex and solve the overcut problem.

Social implications

The directly tool paths generation from a STL model can reduce the error of surface reconstruction and speed up the machining progress.

Originality/value

The authors investigate the overcut problem occurred in vertex offset for CL data generation and present a new error compensation algorithm for generating the CL data that can effectively solve the overcut problem.

Details

Rapid Prototyping Journal, vol. 22 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 15 July 2022

Lulu Huang, Xiang Huang and Shuang-Gao Li

The size of the aircraft tooling structure is huge, and the ambient temperature is difficult to maintain a constant state. Aiming at the influence of current temperature, this…

Abstract

Purpose

The size of the aircraft tooling structure is huge, and the ambient temperature is difficult to maintain a constant state. Aiming at the influence of current temperature, this paper aims to propose a compensation method for registration error of large-scale measurement fields based on multi-temperature sensors.

Design/methodology/approach

In this method, an enhanced reference points (ERS)–temperature regression model is constructed from ERS and temperature data. The ERS offsets compensation model is established by solving the offset through the regression model, and the ERS offset compensation analysis is carried out.

Findings

The experimental results show that the proposed registration error compensation algorithm has obvious advantages over traditional methods in reducing the influence of ambient temperature and improving the measurement accuracy by reducing the registration error.

Originality/value

This method reduces registration error caused by the influence of ambient temperature and is used for aircraft measurements in different temperature environments.

Details

Sensor Review, vol. 42 no. 5
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 17 May 2023

Lulu Huang, Xiang Huang and Shuanggao Li

Large size of aircraft assembly tooling structure and complex measurement environment exist. The laid enhanced reference points (ERS) are subject to a combination of nonuniform…

Abstract

Purpose

Large size of aircraft assembly tooling structure and complex measurement environment exist. The laid enhanced reference points (ERS) are subject to a combination of nonuniform temperature fields and measurement errors, resulting in increased measurement registration errors. In view of the nonuniform temperature field and measurement errors affecting the ERS point registration problem, the purpose of this paper is to propose a neural network-based ERS point registration compensation method for large-size measurement fields under a nonuniform temperature field.

Design/methodology/approach

The approach is to collect ERS point information and temperature data, normalize the collected data to complete the data structure design and complete the construction of the neural network prediction model by data training. The data learning is performed to complete the prediction model construction, and the prediction model is used to complete the compensation analysis of ERS points. Finally, the algorithm is verified through experiments and engineering practice.

Findings

Experimental results show that the proposed neural network-based ERS point prediction and compensation method for nonuniform temperature fields effectively predicts ERS point deformation under nonuniform temperature fields compared with the conventional method. After the compensation analysis, the registration error is effectively reduced to improve registration accuracy. Reducing the combined effect of environmental nonuniform temperature field and measurement error has apparent advantages.

Originality/value

The method reduces the registration error caused by combining a nonuniform temperature field and measurement error. It can be used for aircraft assembly site prediction and registration error compensation analysis, which is essential to improve measurement accuracy further.

Details

Robotic Intelligence and Automation, vol. 43 no. 2
Type: Research Article
ISSN: 2754-6969

Keywords

Article
Publication date: 8 June 2022

Han Liu, Guojin Yang and Rong Wang

The wireless power transmission (WPT) system with an embedded coil will achieve a more flexible charging operation and higher system efficiency. However, the comprehensive…

Abstract

Purpose

The wireless power transmission (WPT) system with an embedded coil will achieve a more flexible charging operation and higher system efficiency. However, the comprehensive analysis considering cross-coupling for WPT with embedded coil is rarely investigated. This study aims to improve the system efficiency of WPT with the embedded coil based on circuit analysis and optimization of embedded coil loops.

Design/methodology/approach

The circuit model of WPT system with the non-resonant compensated embedded coil is developed by taking the cross-coupling of all coils and the circuit compensation degree of the embedded coil into consideration. On the basis of system characteristics analysis, optimization of embedded coil position and non-resonant compensation are proposed to improve the efficiency of WPT system with embedded coil. Experimental studies demonstrate the correctness of theoretical research.

Findings

The WPT system with embedded coil designed by optimizing the position and non-resonant compensation achieves higher efficiency than those of the system with two-coil mode and the three-coil system with a resonant compensated embedded coil.

Practical implications

A WPT system with embedded coil could be more efficient by using a non-resonant compensated coil embedded into the buffer material of the storage box for sophisticated electrical equipment.

Originality/value

The cross-coupling between all coils is considered in circuit analysis for WPT system with embedded coil. Optimization of the position and non-resonant compensation of embedded coil achieves higher efficiency.

Details

Circuit World, vol. 49 no. 4
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 18 January 2016

Carlos Cajal, Jorge Santolaria, David Samper and Jesus Velazquez

This paper aims to present a methodology for volumetric error compensation. This technique is applied to an Objet Eden350V 3D printer and involves a custom measurement strategy…

Abstract

Purpose

This paper aims to present a methodology for volumetric error compensation. This technique is applied to an Objet Eden350V 3D printer and involves a custom measurement strategy.

Design/methodology/approach

The kinematic model of the printer is explained, and its error model is simplified to 18 independent error functions. Each error function is defined by a cubic Legendre polynomial. The coefficients of the polynomials are obtained through a Levenberg–Marquardt optimization process. This optimization process compares, in an iterative algorithm, nominal coordinates with actual values of the cloud of points. The points are built in the faces of a gauge artefact as conical sockets defining one unique point for each socket. These points are measured by a coordinate measuring machine self-centring measurement process.

Findings

Most of the errors of the 3D printer are systematic. It is possible to obtain an improvement of 70 per cent in terms of global mean error reduction in single points within a volume of 120 × 120 × 40 mm. The forecast of the final error compensation fully matches the actual final error.

Practical implications

This methodology can be used for accuracy improvement in additive manufacturing machines.

Originality/value

Unlike the calculation of geometric errors, the proposed parametric determination through optimization of the error model allows global error reduction, which decreases all sort of systematic errors concurrently. The proposed measurement strategy allows high reliability, high speed and operator independence in the measurement process, which increases efficiency and reduces the cost. The proposed methodology is easily translated to other rapid prototyping machines and allows scalability when replicating artefacts covering any working volume.

Article
Publication date: 7 September 2015

Faisal L Kadri

The purpose of this paper is to introduce signature analysis to humour research. Signature analysis is not widely used in the fields of humanities, the introduction of a new…

Abstract

Purpose

The purpose of this paper is to introduce signature analysis to humour research. Signature analysis is not widely used in the fields of humanities, the introduction of a new technique will invite comparison with the long standing factor analysis method.

Design/methodology/approach

A signature presumes the existence of a model with ideal attributes for the purpose of identification. The model derived from types of humour which describe four types of age dependence. Age dependence contrast sharply with factor analysis which usually ignores age differences in humour. The signatures of four types of humour were calculated from the average scores of all line scores of each type. The Cramer-Rao Bounds were also calculated from the same groups, this defines the centre points and the limits of best type estimators. The age profiles of individual lines were plotted against their type signatures. The error distributions were plotted, with and without offset compensation.

Findings

The error plot with offset compensation showed a spike close to the zero error, indicating the existence of significant matching between profiles and signature.

Research limitations/implications

This is an exploratory analysis of responses from 277 participants in an online long survey. More participation is required/hoped for to confirm these findings.

Practical implications

The graphical identification of context in sentences, humorous and non-humorous.

Originality/value

Signature analysis is well known in the physical sciences, the author knows of no application in psychology or humour research.

Details

Kybernetes, vol. 44 no. 8/9
Type: Research Article
ISSN: 0368-492X

Keywords

Article
Publication date: 18 September 2017

Carlos Ferreira

The purpose of this paper is to analyse the processes involved in the creation and eventual demise of a market for biodiversity offsets in the UK. The reasons for the failure of…

1395

Abstract

Purpose

The purpose of this paper is to analyse the processes involved in the creation and eventual demise of a market for biodiversity offsets in the UK. The reasons for the failure of this market to take hold as a governance mechanism are considered, and its subsequent effects examined.

Design/methodology/approach

The research examines a single case study of the creation of a pilot market for biodiversity offsets in the UK. Data include policy and industry papers, complemented with interviews with biodiversity offset practitioners, regulators and non-government organisations.

Findings

The case study demonstrates that a market for biodiversity offsets was piloted with the intent to contribute to the reform of the UK planning regime. However, disagreements about this political project, uncertainties in the knowledge base, and continued entanglements with existing biodiversity meant it was impossible to stabilise the assemblages necessary to support the market, leading to its eventual demise. However, the principles and devices of offsetting have proved more resilient, and have started to combine with the existing arrangements for the governance of nature.

Practical implications

The paper presents a situation where a political project to reform governance arrangements through the creation of a market was not successful, making it of interest to researchers and policymakers alike.

Originality/value

While biodiversity offsetting has been widely discussed from scientific, legal and political perspectives, this paper addresses it as a market, explicitly designed to become a part of a governance regime. It also advances the understanding of the mechanisms by which similar processes of marketisation can fail, and suggests avenues for future research in those contexts.

Details

Accounting, Auditing & Accountability Journal, vol. 30 no. 7
Type: Research Article
ISSN: 0951-3574

Keywords

Article
Publication date: 26 September 2023

Dangshu Wang, Xuan Deng, Zhimin Guan, Shulin Liu, Yaqiang Yang and Xinxia Wang

To simplify the circuit design and control complexity of the magnetic coupling resonant wireless charging system, the radio energy transmission constant current and constant…

45

Abstract

Purpose

To simplify the circuit design and control complexity of the magnetic coupling resonant wireless charging system, the radio energy transmission constant current and constant voltage charging is realized.

Design/methodology/approach

The purpose of this study is to simplify the circuit design and control complexity of the magnetic coupling resonance wireless charging system, in order to achieve constant current and constant voltage charging for wireless energy transmission. First, the principle of LCC/S-S compensation structure is analyzed, and the equivalent mathematical model is established; then, the system characteristics under constant current and constant voltage mode are analyzed, and the design method of system parameters is given; finally, a simulation and experimental system is built to verify the correctness and feasibility of the theoretical analysis.

Findings

The results show that the proposed hybrid topology can achieve a constant current output of 2 A and a constant voltage output of 30 V under variable load conditions, and effectively suppress the current distortion problem under light load conditions. The waveform distortion rate of the inverter current is reduced from 33.97% to 10.45%.

Originality/value

By changing the high-order impedance characteristics of the compensation structure, the distortion of the current waveform under light load is suppressed, and the overall stability and efficiency of the system are improved.

Details

Circuit World, vol. 50 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 13 August 2018

Sami Elferik, Mohammed Hassan and Mustafa AL-Naser

The purpose of this paper is to improve the performance of control loop suffering from control valve stiction. Control valve stiction is considered as of one of the main causes of…

Abstract

Purpose

The purpose of this paper is to improve the performance of control loop suffering from control valve stiction. Control valve stiction is considered as of one of the main causes of oscillation in process variables, which require performing costly unplanned maintenance and process shutdown. An adaptive solution to handle valve stiction while maintaining safety and quality until next planned maintenance is highly desirable to save considerable cost and effort.

Design/methodology/approach

This paper implements a new stiction compensation method built using adaptive inverse model techniques and intelligent control theories. Finite impulse response (FIR) model, which is known to be robust, as a compensator for stiction. The parameters of FIR model are tuned in an adaptive way using differential evolution (DE) technique. The performance of proposed method is compared with other two compensation techniques.

Findings

The new method showed excellent performance of the DE–FIR compensator compared to other dynamic inversion methods in terms of minimizing process variability, energy saving and valve stem aggressiveness.

Research limitations/implications

The compensation ability for all compensators reduces with the increase of stiction severity, thus the over shoot case always shows the worst result. In future works, other optimization techniques will be explored to find the appropriate technique that can extend the FIR model size with smallest computation time that can improve the performance of the compensator in over shoot case. In addition, the estimation of the valve residual life based on the level of stiction and effort required by the controller should be considered.

Originality/value

The presented approach represents an original contribution to the literature. It performs stiction compensation without a need for a prior knowledge on the process or the valve models and guarantees a smooth control of the stem movement with a low control effort. The proposed approach differs from previous adaptive methods as it uses stable FIR models and DE to find the appropriate parameters of the inverse model and handle nonlinear behavior of stiction.

Details

Journal of Quality in Maintenance Engineering, vol. 24 no. 3
Type: Research Article
ISSN: 1355-2511

Keywords

Article
Publication date: 9 August 2011

Hamza Bahaji

This paper aims to analyze the valuation of stock options from the perspective of an employee exhibiting preferences as described by cumulative prospect theory (CPT). In addition…

1583

Abstract

Purpose

This paper aims to analyze the valuation of stock options from the perspective of an employee exhibiting preferences as described by cumulative prospect theory (CPT). In addition, it elaborates on their incentives effect and some implications in terms of design aspects.

Design/methodology/approach

The paper draws on the CPT framework to derive a continuous time model of the stock option subjective value using the certainty equivalence principle. Numerical simulations are used in order to analyze the subjective value sensitivity with respect to preferences‐related parameters and to investigate the incentives effect.

Findings

Consistent with a growing body of empirical and experimental studies, the model predicts that the employee may overestimate the value of his options in‐excess of their risk‐neutral value. Moreover, for typical setting of preferences parameters around the experimental estimates, and assuming the company is allowed to adjust existing compensation when making new stock option grants, the model predicts that incentives are maximized for strike prices set around the stock price at inception. This finding is consistent with companies’ actual compensation practices. Finally, the model predicts that an executive who is subject to probability weighting may be more prompted than a risk‐neutral executive to act in order to increase the firm's assets volatility.

Originality/value

This research proposes an alternative theoretical framework for the analysis of pay‐to‐performance sensitivity of equity‐based compensation that takes into account a number of prominent patterns of employee behavior that expected utility theory cannot explain. It contributes to recent empirical and theoretical researches that have advanced CPT framework as a promising candidate for the analysis of equity‐based compensation contracts.

Details

Review of Accounting and Finance, vol. 10 no. 3
Type: Research Article
ISSN: 1475-7702

Keywords

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