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Article
Publication date: 1 February 1980

V.A. Belyi, I.V. Kragelskii, V.G. Savkin and A.I. Sviridyonok

EXPERIMENTAL WORK AND RESULTS I. Physical Methods of Polymer Modification PHYSICAL methods can be used to modify the structure of super‐molecules in order to control the…

83

Abstract

EXPERIMENTAL WORK AND RESULTS I. Physical Methods of Polymer Modification PHYSICAL methods can be used to modify the structure of super‐molecules in order to control the mechanical properties of the polymer and revise the frictional properties over a wide range while keeping the chemical structure and molecular weight unchanged.

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Industrial Lubrication and Tribology, vol. 32 no. 2
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 1 April 2001

Min Zhi Rong, Ming Qiu Zhang, Hong Liu, Hanmin Zeng, Bernd Wetzel and Klaus Friedrich

Nanocomposites represent a new prospective branch in the huge field of polymer materials science and technology. It has been shown that an overall enhancement of properties of…

1527

Abstract

Nanocomposites represent a new prospective branch in the huge field of polymer materials science and technology. It has been shown that an overall enhancement of properties of polymers can be achieved under certain conditions by the addition of nanoparticles. To examine the influence of microstructure on the tribological performance of nanocomposites, different ways of compounding were used in this study. It was found that the friction and wear behavior of polymeric nanocomposites under sliding environment was rather sensitive to the dispersion states of the nanoparticles. When the microstructural homogeneity of the nanocomposites was improved, their wear resistance could be increased significantly. The present work demonstrates the importance of TiO2‐nanoparticles dispersion in an epoxy resin matrix, on the materials’ tribological properties, when sliding against a smooth steel counterpart.

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Industrial Lubrication and Tribology, vol. 53 no. 2
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 3 May 2011

Stanisław Krawiec

The purpose of this paper is to find a reason of a very high lubrication effectivity of a lithium grease filled with PTFE and copper powders when used as a lubricant between…

354

Abstract

Purpose

The purpose of this paper is to find a reason of a very high lubrication effectivity of a lithium grease filled with PTFE and copper powders when used as a lubricant between contacting steel surfaces under mixed friction conditions.

Design/methodology/approach

The paper presents the results of the differential thermal analysis (DTA) of a lithium grease lubricant filled with 6 wt% PTFE and 6 wt% Cu and of a 1:1 mass mixture of PTFE and copper powders alone. The chemical composition analysis of post‐DTA residual substances was carried out using the x‐ray microanalysis. The same method was employed for the examination of the chemical composition of the post‐test friction area in the balls of a four‐ball apparatus. The balls were lubricated with three greases: without any fillers (the base 1S lithium grease), with one filler (6 wt% Cu), and with two fillers (6 wt% PTFE and 6 wt% Cu). For the latter compound, the load was 500 daN, for the remaining compositions, the load was 126 daN.

Findings

The results of the analyses done confirmed a thesis that the synergism of PTFE and Cu in the tested grease under mixed friction conditions is possible due to the thermal decomposition of PTFE and creation – as a result of a reaction of this decomposition products with an earlier formed platering layer – of new layers that are (to a high probability) complexes containing copper, fluorine, and sulphur.

Practical implications

PTFE and copper powders when used as fillers for a lithium grease form a very effective lubrication compound for steel sliding pairs. The application of this compound results in an overall reduction of friction and wear that is greater than a simple summation of gains obtained when using these two additives separately.

Originality/value

It was proved that a dominant factor contributing to the synergistic effect of PTFE and copper in a lithium grease when used for the lubrication of steel surfaces is the fluorine that originate from the thermal disintegration of PTFE and not sulphur from the base grease.

Details

Industrial Lubrication and Tribology, vol. 63 no. 3
Type: Research Article
ISSN: 0036-8792

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Book part
Publication date: 1 August 2019

O.K. Lukhovskaya, O.Y. Guryeva, V.I. Perov, I.V. Malova and T.S. Kochetkova

The policy of strategic diagnostics in the modern economy of Russia's regions is built in a contradiction. The expected growth of the share of material production in GRP was not…

Abstract

The policy of strategic diagnostics in the modern economy of Russia's regions is built in a contradiction. The expected growth of the share of material production in GRP was not confirmed. Analysis of economic indicators allows stating the expected tendency in dynamics of development of tertiary spheres. A dominating element of structural changes of economy is consumer market.

Several methodological approaches to defining the category “consumer market” are distinguished: marketing, institutional, reproduction, and economic.

For formation of methodological foundations of evaluation of consumer market, several methodologies are systematized. A methodology including two stages of evaluation of development of consumer market is offered: diagnostics (first stage) and forecasting (second stage) of the region's consumer market.

According to evaluations obtained by the authors, a strategic factor of structural changes in Russia's economy is regions' consumer market. Its well-balanced development ensures acceleration of progressive structural changes in economy. A dominating factor in the structure of consumer market is trading sphere, and a tool of structural changes is trading the goods of local and domestic manufacturers.

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Article
Publication date: 13 February 2024

Amer Jazairy, Emil Persson, Mazen Brho, Robin von Haartman and Per Hilletofth

This study presents a systematic literature review (SLR) of the interdisciplinary literature on drones in last-mile delivery (LMD) to extrapolate pertinent insights from and into…

4694

Abstract

Purpose

This study presents a systematic literature review (SLR) of the interdisciplinary literature on drones in last-mile delivery (LMD) to extrapolate pertinent insights from and into the logistics management field.

Design/methodology/approach

Rooting their analytical categories in the LMD literature, the authors performed a deductive, theory refinement SLR on 307 interdisciplinary journal articles published during 2015–2022 to integrate this emergent phenomenon into the field.

Findings

The authors derived the potentials, challenges and solutions of drone deliveries in relation to 12 LMD criteria dispersed across four stakeholder groups: senders, receivers, regulators and societies. Relationships between these criteria were also identified.

Research limitations/implications

This review contributes to logistics management by offering a current, nuanced and multifaceted discussion of drones' potential to improve the LMD process together with the challenges and solutions involved.

Practical implications

The authors provide logistics managers with a holistic roadmap to help them make informed decisions about adopting drones in their delivery systems. Regulators and society members also gain insights into the prospects, requirements and repercussions of drone deliveries.

Originality/value

This is one of the first SLRs on drone applications in LMD from a logistics management perspective.

Details

The International Journal of Logistics Management, vol. 36 no. 7
Type: Research Article
ISSN: 0957-4093

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Article
Publication date: 17 April 2019

Hu Xiao, Rongxin Cui and Demin Xu

This paper aims to present a distributed Bayesian approach with connectivity maintenance to manage a multi-agent network search for a target on a two-dimensional plane.

477

Abstract

Purpose

This paper aims to present a distributed Bayesian approach with connectivity maintenance to manage a multi-agent network search for a target on a two-dimensional plane.

Design/methodology/approach

The Bayesian framework is used to compute the local probability density functions (PDFs) of the target and obtain the global PDF with the consensus algorithm. An inverse power iteration algorithm is introduced to estimate the algebraic connectivity λ2 of the network. Based on the estimated λ2, the authors design a potential field for the connectivity maintenance. Then, based on the detection probability function, the authors design a potential field for the search target. The authors combine the two potential fields and design a distributed gradient-based control for the agents.

Findings

The inverse power iteration algorithm can distributed estimate the algebraic connectivity by the agents. The agents can efficient search the target with connectivity maintenance with the designed distributed gradient-based search algorithm.

Originality/value

Previous study has paid little attention to the multi-agent search problem with connectivity maintenance. Our algorithm guarantees that the strongly connected graph of the multi-agent communication topology is always established while performing the distributed target search problem.

Details

Assembly Automation, vol. 40 no. 1
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 24 October 2023

Zijing Ye, Huan Li and Wenhong Wei

Path planning is an important part of UAV mission planning. The main purpose of this paper is to overcome the shortcomings of the standard particle swarm optimization (PSO) such…

145

Abstract

Purpose

Path planning is an important part of UAV mission planning. The main purpose of this paper is to overcome the shortcomings of the standard particle swarm optimization (PSO) such as easy to fall into the local optimum, so that the improved PSO applied to the UAV path planning can enable the UAV to plan a better quality path.

Design/methodology/approach

Firstly, the adaptation function is formulated by comprehensively considering the performance constraints of the flight target as well as the UAV itself. Secondly, the standard PSO is improved, and the improved particle swarm optimization with multi-strategy fusion (MFIPSO) is proposed. The method introduces class sigmoid inertia weight, adaptively adjusts the learning factors and at the same time incorporates K-means clustering ideas and introduces the Cauchy perturbation factor. Finally, MFIPSO is applied to UAV path planning.

Findings

Simulation experiments are conducted in simple and complex scenarios, respectively, and the quality of the path is measured by the fitness value and straight line rate, and the experimental results show that MFIPSO enables the UAV to plan a path with better quality.

Originality/value

Aiming at the standard PSO is prone to problems such as premature convergence, MFIPSO is proposed, which introduces class sigmoid inertia weight and adaptively adjusts the learning factor, balancing the global search ability and local convergence ability of the algorithm. The idea of K-means clustering algorithm is also incorporated to reduce the complexity of the algorithm while maintaining the diversity of particle swarm. In addition, the Cauchy perturbation is used to avoid the algorithm from falling into local optimum. Finally, the adaptability function is formulated by comprehensively considering the performance constraints of the flight target as well as the UAV itself, which improves the accuracy of the evaluation model.

Details

International Journal of Intelligent Computing and Cybernetics, vol. 17 no. 2
Type: Research Article
ISSN: 1756-378X

Keywords

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Book part
Publication date: 25 July 2024

Vic Benuyenah

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Article
Publication date: 16 July 2024

Chandresh Kumbhani and Ravi Kant

Strategic integration of enablers and the realization of drone delivery benefits emerge as essential strategies for business organizations to enhance operational efficiency and…

166

Abstract

Purpose

Strategic integration of enablers and the realization of drone delivery benefits emerge as essential strategies for business organizations to enhance operational efficiency and stay competitive in last-mile logistics. This paper aims to explore the benefits of drone-based last-mile delivery in the Indian logistic sector by providing a framework for ranking drone delivery benefits (DDBs) due to the adoption of its enablers.

Design/methodology/approach

This study proposes a novel hybrid framework applied in the Indian logistic sector by integrating a sentence boundary extraction algorithm for extracting benefits from literature, a spherical fuzzy analytical hierarchy process (SF-AHP) for evaluating primary enablers, unsupervised fuzzy C-means clustering (FCM) for clustering benefits and a spherical combined compromised solution (SF-CoCoSo) for ranking benefits with respect to primary enablers.

Findings

The results reveal that technological and infrastructure enablers (TIE), government and legislation enablers (GLE) and operational and service quality enablers (OSE) are the most significant enablers for drone implementation in logistics. Top-ranked benefits increase the efficiency of last-mile delivery (DDB10), foster supply chain management and logistic sustainability (DDB16) and increase delivery access to rural area and vulnerable people (DDB17).

Practical implications

This research assists scholars, entrepreneurs and policymakers in the sustainable deployment of drone delivery in the logistics sector. This study facilitates the use of drones in delivery services and provides a foundation for all stakeholders in logistics.

Originality/value

The assessments involve considering judgment from a highly knowledgeable and experienced group in India, characterized by a large volume of inputs and a high level of expertise.

Details

Journal of Advances in Management Research, vol. 21 no. 5
Type: Research Article
ISSN: 0972-7981

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Article
Publication date: 16 April 2018

Tahir Islam, Zaryab Sheikh, Zahid Hameed, Ikram Ullah Khan and Rauf I. Azam

The purpose of this paper is to provide the overview of factors responsible for materialism and compulsive buying among adolescents and young adults. In today’s world, materialism…

10309

Abstract

Purpose

The purpose of this paper is to provide the overview of factors responsible for materialism and compulsive buying among adolescents and young adults. In today’s world, materialism is a crucial phenomenon of the modern age. According to social comparison theory, comparisons are a significant factor affecting the behavioral intentions of adolescents and young adults. Thus, this study develops a framework based on the stimulus–organism–response model and uses the framework to examine the impact of interpersonal communication and marketing factors on social comparison, materialism and compulsive buying, with social media acting as a moderator.

Design/methodology/approach

Using a survey method, data were collected in Study 1 from adolescents (n = 298) and in Study 2 from young adults (n = 345). Structural equation modeling analysis using partial least squares technique was used to analyze the data.

Findings

The results show that social comparison plays a significant role in developing materialistic values and compulsive buying among adolescents and young adults. Through these two studies, it was found that young adults are more socially comparative, materialistic and compulsive in buying as compared to adolescents. Moreover, social media use moderated the relationship between social comparison with peers and media celebrities, which means that rapid increase of social media use leads adolescents and young adults to create high social comparison and materialistic values.

Research limitations/implications

This research is based on the cross-sectional method, which limits the research findings.

Practical implications

This research helps corporate managers understand the interpersonal communication role in creating social comparison among individuals. The study found that peer communication plays a more important role in enhancing the social comparative values among young adults than among adolescents, which provides clear implications for the practitioner.

Originality/value

This study makes a significant contribution to extant literature by discussing the above issue and presenting quantitative data. The study extends the literature by examining and validating a theoretical model of how interpersonal communication among socializing agents affects social comparison among young adults and adolescents. This research examines outcomes of the social comparison with parents, peers and social media, based on the stimulus–organism–response (SOR) model.

Details

Young Consumers, vol. 19 no. 1
Type: Research Article
ISSN: 1747-3616

Keywords

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