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Article
Publication date: 18 January 2016

Mostafa Mahmoodi, Khalil Alipour and Hadi Beik Mohammadi

The purpose of this paper is to propose an efficient method, called kinodynamic velocity obstacle (KidVO), for motion planning of omnimobile robots considering kinematic and…

193

Abstract

Purpose

The purpose of this paper is to propose an efficient method, called kinodynamic velocity obstacle (KidVO), for motion planning of omnimobile robots considering kinematic and dynamic constraints (KDCs).

Design/methodology/approach

The suggested method improves generalized velocity obstacle (GVO) approach by a systematic selection of proper time horizon. Selection procedure of the time horizon is based on kinematical and dynamical restrictions of the robot. Toward this aim, an omnimobile robot with a general geometry is taken into account, and the admissible velocity and acceleration cones reflecting KDCs are derived, respectively. To prove the advantages of the suggested planning method, its performance is compared with GVOs, the so-called Hamilton-Jacobi-Bellman equation and the rapidly exploring random tree.

Findings

The obtained results of the presented scenarios which contain both computer and real-world experiments for complicated crowded environments indicate the merits of the suggested methodology in terms of its near-optimal behavior, successful obstacle avoidance both in static and dynamic environments and reaching to the goal pose.

Originality/value

This paper proposes a novel method for online motion planning of omnimobile robots in dynamic environments while considering the real capabilities of the robot.

Details

Industrial Robot: An International Journal, vol. 43 no. 1
Type: Research Article
ISSN: 0143-991X

Keywords

Available. Open Access. Open Access
Article
Publication date: 25 July 2024

Guler Aras

126

Abstract

Details

Journal of Capital Markets Studies, vol. 8 no. 1
Type: Research Article
ISSN: 2514-4774

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Article
Publication date: 4 June 2024

Ali Asghar Mahmoodi, Mohammadreza Abdoli, Maryam Shahri and Farhad Dehdar

The purpose of this research is to investigate the importance and status of conditional accounting conservatism indicators and financial flexibility for the management of legal…

88

Abstract

Purpose

The purpose of this research is to investigate the importance and status of conditional accounting conservatism indicators and financial flexibility for the management of legal claims of the company during the outbreak of Corona.

Design/methodology/approach

The research method was implemented using statistical analysis in the SPSS environment. The participants of this research can be experts and specialists working in companies admitted to the stock exchange and expert professors in accounting fields; auditing; economy; financial engineering and financial management, categorized. The data related to the localization tool of research variables were collected by snowball sampling method in the summer of 2022.

Findings

One of the main results of the research is that based on the opinions and professional experience of experts and professionals working in companies admitted to the stock exchange and academic experts, within a range of seven, “The number of legal claims of the company with electronic businesses” under the title of the main indicator in the legal claims of the company in the outbreak of Corona from the importance dimension; “Exchange rate fluctuations in financial resilience” under the title of the main indicator in financial resilience in the Corona outbreak from the functional dimension; “The number of legal claims of the company with government institutions” under the title of the main indicator in the company’s legal claims in the Corona outbreak from the functional dimension; “The company’s conservatism score” under the title of the main indicator in the conditional conservatism of accounting in the Corona outbreak from the functional dimension; “oil price fluctuations in financial resilience” under the title of the main indicator in financial resilience in the Corona outbreak from the importance dimension; and “type of industry based on total assets” under the title of the main indicator in the conditional conservatism of accounting in the Corona outbreak was calculated from the importance dimension.

Originality/value

Although the previous literature has studied the direct correlation between accounting conservatism and financial flexibility, this work focuses on examining the direct association between accounting conservatism and financial flexibility in the post-Corona era and is carried out to resolve legal claims.

Details

International Journal of Law and Management, vol. 67 no. 2
Type: Research Article
ISSN: 1754-243X

Keywords

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Article
Publication date: 18 February 2019

Mohammed S. Gumaan, Rizk Mostafa Shalaby, Mustafa Kamal Mohammed Yousef, Esmail A.M. Ali and E. E. Abdel-Hady

This study aims to investigate the structural, mechanical, thermal and electrical properties of tin–silver–nickel (Sn-Ag-Ni) melt-spun solder alloys. So, it aims to improve the…

243

Abstract

Purpose

This study aims to investigate the structural, mechanical, thermal and electrical properties of tin–silver–nickel (Sn-Ag-Ni) melt-spun solder alloys. So, it aims to improve the mechanical properties of the eutectic tin–silver (Sn-Ag) such as tensile strength, plasticity and creep resistance by adding different concentrations of Ni content.

Design/methodology/approach

Ternary melt-spun Sn-Ag-Ni alloys were investigated using x-ray diffractions, scanning electron microscope, dynamic resonance technique (DRT), Instron machine, Vickers hardness tester and differential scanning calorimetry.

Findings

The results revealed that the Ni additions 0.1, 0.3, 0.5, 0.7, 1, 3 and 5 Wt.% to the eutectic Sn-Ag melt-spun solder were added. The “0.3wt.%” of Ni was significantly improved its mechanical properties to efficiently serve under high strain rate applications. Moreover, the uniform distribution of Ag3Sn intermetallic compound with “0.3wt.%” of Ni offered the potential benefits, such as high strength, good plasticity consequently and good mechanical performance through a lack of dislocations and microvoids. The tensile results showed improvement in 17.63 per cent tensile strength (26 MPa), 21 per cent toughness (1001 J/m3), 22.83 per cent critical shear stress (25.074 MPa) and 11 per cent thermal diffusivity (2.065 × 10−7 m2/s) when compared with the tensile strength (21.416 MPa), toughness (790 J/m3), critical shear stress (19.348 MPa) and thermal diffusivity (1.487 × 10−7 m2/s) of the eutectic Sn-Ag. Slight increments have been shown for the melting temperature of Sn96.2-Ag3.5-Ni0.3 (222.62°C) and electrical resistivity to (1.612 × 10−7 Ω.m). It can be said that the eutectic Sn-Ag solder alloy has been mechanically improved with “0.3wt.%” of Ni to become a suitable alloy for high strain rate applications. The dislocation movement deformation mechanism (n = 4.5) without Ni additions changed to grain boundary sliding deformation mechanism (n = 3.5) with Ni additions. On the other hand, the elastic modulus, creep rate and strain rate sensitivity with “0.3wt.%” of Ni have been decreased. The optimum Ni-doped concentration is “0.7wt.%” of Ni in terms of refined microstructure, electrical resistivity, Young’s Modulus, bulk modulus, shear modulus, thermal diffusivity, maximum shear stress, tensile strength and average creep rate.

Originality/value

This study provides nickel effects on the structural of the eutectic Sn-Ag rapidly solidified by melt-spinning technique. In this paper, the authors have compared the elastic modulus of the melt-spun compositions which has been resulted from the tensile strength tester with these results from the DRT for the first time to best of the authors’ knowledge. This paper presents new improvements in mechanical and electrical performance.

Details

Soldering & Surface Mount Technology, vol. 31 no. 1
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 28 June 2022

Rizk Mostafa Shalaby and Musaeed Allzeleh

This study aims to study the impact of intermetallic compound on microstructure, mechanical characteristics and thermal behavior of the melt-spun Bi-Ag high-temperature lead-free…

118

Abstract

Purpose

This study aims to study the impact of intermetallic compound on microstructure, mechanical characteristics and thermal behavior of the melt-spun Bi-Ag high-temperature lead-free solder.

Design/methodology/approach

In this paper, a new group of lead-free high-temperature Pb-free solder bearing alloys with five weight percentages of different silver additions, Bi-Agx (x = 3.0, 3.5, 4.0, 4.5 and 5.0 Wt.%) have been developed by rapidly solidification processing (RSP) using melt-spun technique as a promising candidate for the replacement of conventional Sn-37Pb common solder. The effect of the addition of a small amount of Ag on the structure, microstructure, thermal and properties of Bi-Ag solder was analyzed by means of X-ray diffractometer, scanning electron microscopy, differential scanning calorimetry and Vickers hardness technique. Applying the RSP commonly results in departures from conventional microstructures, giving an improvement of grain refinement. Furthermore, the grain size of rhombohedral hexagonal phase Bi solid solution and cubic IMC Bi0.97Ag0.03 phase is refined by Ag addition. Microstructure analysis of the as soldered revealed that relatively uniform distribution, equiaxed refined grains of secondary IMC Bi0.97Ag0.03 particles about 10 µm for Bi-Ag4.5 dispersed in a Bi matrix. The addition of trace Ag led to a decrease in the solidus and liquidus temperatures of solder, meanwhile, the mushy zone is about 11.4°C and the melting of Sn-Ag4.5 solder was found to be 261.42°C which is lower compared with the Sn-Ag3 solder 263.60°C. This means that the silver additions into Bi enhance the melting point. The results indicate that an obvious change in electrical resistivity (?) at room temperature was noticed by the Ag addition. It was also observed that the Vickers microhardness (Hv) was increased with Ag increasing from 118 to 152 MPa. This study recommended the use of the Bi-Ag lead-free solder alloys for higher temperature applications.

Findings

Silver content is very important for the soldering process and solder joint reliability. Based on the present investigations described in this study, several conclusions were found regarding an evaluation of microstructural and mechanical deformation behavior of various Bi-Ag solders. The effect of Ag and rapid solidification on the melting characteristics, and microstructure of Bi-Ag alloys were studied. In addition, the mechanical properties of Bi with different low silver were investigated. From the present experimental study, the following conclusions can be drawn. The addition of Ag had a marked effect on the melting temperature of the lead-free solder alloys, it decreases the melting temperature of the alloy from 263.6 to 261.42°C. Bi-Ag solders are comprised of rhombohedral Hex. Bi solid solution and cubic Ag0.97Bi0.03 IMC is formed in the Bi matrix. The alloying of Ag could refine the primary Bi phase and the Bi0.97Ag0.03 IMC. With increasing Ag content, the microstructure of the Bi-Ag gradually changes from large dimples into tiny dimple-like structures. The refinement of IMC grains was restrained after silver particles were added into the matrix. The inhibition effect on the growth of IMC grains was most conspicuous when solder was doped with Ag particles. As a result, the Vickers microhardness of the Bi-Ag lead-free solder alloys was enhanced by more than 100% ranging from 118.34 to 252.95 MPa. Bi-Ag high-temperature lead-free solders are a potential candidate for replacing the tin-lead solder (Sn-37Pb) materials which are toxic to human and the environment and has already been banned.

Originality/value

This study recommended the use of the Bi-Ag lead-free solder alloys for high-temperature applications.

Details

Soldering & Surface Mount Technology, vol. 35 no. 2
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 10 November 2022

Maryam Dehghani, Peyman Akhavan and Morteza Abbasi

This study aims to propose a quantitative approach to reduce the number of suppliers in an organization. This method is based on grouping, and different parts are grouped based on…

141

Abstract

Purpose

This study aims to propose a quantitative approach to reduce the number of suppliers in an organization. This method is based on grouping, and different parts are grouped based on the capabilities they need and are allocated to suppliers who have these capabilities. In this regard, an integrated model for supplier reduction and grouping of parts using a group technology-based algorithm is proposed.

Design/methodology/approach

Design science research methodology was used in this study. The main problem under investigation is a large number of suppliers in an organization’s supply base. The proposed model was used to solve this problem in the electric motor industry.

Findings

The results of implementing the proposed model in the electric motor industry showed that reducing suppliers had a significant effect on reducing cost, increasing information sharing, increasing supplier innovation and technology, enhancing the relationship between buyers and sellers and reducing risks in the production process.

Practical implications

From a managerial point of view, reducing the number of suppliers plays an important role in the company’s overall strategy, and seems to be a prerequisite for building a strong supplier partnership and an effective supply chain, and will have many benefits for the focal company and suppliers.

Originality/value

To the best of the authors’ knowledge, grouping and formation of product families have never been performed based on the similarity of the operational capabilities required for producing parts, and it has not been addressed as a solution for reducing suppliers.

Details

Journal of Business & Industrial Marketing, vol. 38 no. 9
Type: Research Article
ISSN: 0885-8624

Keywords

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