Search results

The purpose of this paper is to investigate the friction and sealing characteristics of narrow end face seal ring with spiral grooves for wet clutch by experiment.

The shallow spiral grooves are machined in the end face of narrow seal ring by laser, and all of other parameters of specimens are the same with the actual production. The investigation of friction and sealing characteristics are carried out by comparing the experiment results of end face seal ring with spiral grooves with the conventional seal ring without spiral grooves through friction coefficient test, volume leakage rate test and pv value test.

Comparing with conventional seal ring without spiral grooves, seal ring with spiral grooves experiences boundary lubrication, mixed lubrication and fluid film lubrication with the increase of rotation speed, whereas the conventional seal ring only experiences mixed lubrication. Besides this, the volume leakage rate is slightly larger, but the pv value is much larger than that of conventional seal ring.

Effect of spiral grooves on the friction and sealing characteristics of narrow end face seal ring for wet clutch is investigated. The improved lubrication performance can be achieved by shallow spiral grooves even if the distance of radius difference used to machine grooves is very small.

Presents over sixty abstracts summarising the 1999 Employment Research Unit annual conference held at the University of Cardiff. Explores the multiple impacts of globalization on work and employment in contemporary organizations. Covers the human resource management implications of organizational responses to globalization. Examines the theoretical, methodological, empirical and comparative issues pertaining to competitiveness and the management of human resources, the impact of organisational strategies and international production on the workplace, the organization of labour markets, human resource development, cultural change in organisations, trade union responses, and trans‐national corporations. Cites many case studies showing how globalization has brought a lot of opportunities together with much change both to the employee and the employer. Considers the threats to existing cultures, structures and systems.

The aim of this paper is to construct a device that simulated the seawater splash zone, dynamic waterline zone (splash zone) and full immersion zone. Localized corrosion of 2A12 aluminum alloy long-scale specimen was studied.

Corrosion morphologies before and after the corrosion product removal were used to identify corrosion intensity at full seawater immersion zone, dynamic waterline zone (splash zone) and atmospheric zone. The average depth and diameter of corrosion pits in the three zones were evaluated by three-dimensional optical microscopy. The impact of wetting time of the atmospheric zone on the localized corrosion was investigated.

Corrosion pits were observed on the surface on day 4 for the wetted atmospheric zone (Case 1), and on the surface on day 8 for the alternant wet/dry atmospheric zone (Case 2). The corrosion product layer on the surface for Case 1 was partially broken down while the layer on the surface for Case 2 was intact. Average pitting depth and pitting diameters for Case 1 were more serious than that for Case 2.

The above findings revealed that the humidity of the atmospheric zone had great impact on the localized corrosion of aluminum alloy at the seawater splash zone.

This paper aims to investigate the effect of hexagonal boron nitride (hBN) nanoparticles on extreme pressure (EP) properties when used as an additive in lubricating oil.

The nano-oil was prepared by dispersing an optimal composition of 0.5 vol. per cent of 70 nm hBN in SAE 15W-40 diesel engine oil using a sonication technique. The tribological testing was performed using a four-ball tribometer according to the ASTM standard.

It was found that the nano-oil has a potential to decelerate the seizure point on the contact surfaces, where higher EP can be obtained. More adhesive wear was observed on the worn surfaces of ball bearing lubricated with SAE 15W-40 diesel engine oil as compared with the nano-oil lubrication.

The results of the experimental studies demonstrated the potential of hBN as an additive for improving the load-carrying ability of lubricating oil.

Reorganising unstructured academic abstracts according to a certain logical structure can help scholars not only extract valid information quickly but also facilitate the faceted search of academic literature. This study aims to build a high-performance model for identifying of the functional structures of unstructured abstracts in the social sciences.

This study first investigated the structuring of abstracts in academic articles in the field of social sciences, using large-scale statistical analyses. Then, the functional structures of sentences in the abstract in a corpus of more than 3.5 million abstracts were identified from sentence classification and sequence tagging by using several models based on either machine learning or a deep learning approach, and the results were compared.

The results demonstrate that the functional structures of sentences in abstracts in social science manuscripts include the background, purpose, methods, results and conclusions. The experimental results show that the bidirectional encoder representation from transformers exhibited the best performance, the overall F1 score of which was 86.23%.

The data set of annotated social science abstract is generated and corresponding models are trained on the basis of the data set, both of which are available on Github (https://github.com/Academic-Abstract-Knowledge-Mining/SSCI_Abstract_Structures_Identification). Based on the optimised model, a Web application for the identification of the functional structures of abstracts and their faceted search in social sciences was constructed to enable rapid and convenient reading, organisation and fine-grained retrieval of academic abstracts.

The purpose of this paper is to provide a solution to investigate the deception effects of the radar equipped with decoys.

Since the attacking process of the anti‐radiation missile (ARM) is very complicated, numerical simulations are used here to analyze the effects of the operating parameters and the layout parameters of the radar and the decoys on the survival probabilities.

The survival probabilities of all the radar and the decoys can be over 99.5 percent when three decoys distribute near the radar in an appropriate way and the decoy level is set to some appropriate values.

The movement model of the ARM is simple and should be improved further.

The numerical results may be applied directly in practice and the dynamic simulation algorithms may be as a reference of the radar‐decoy technique in the future works.

Some coordinate systems are built. Based on it, the models of the radar and decoys against an ARM are introduced, including the fields radiated by the radar and the decoys, the guidance signal and the movement of the ARM. Numerical simulations have been performed here. Some conclusions have been given.

The purpose of this paper is to discuss the impacts of the communication time-delays to the distributed containment control of the second-order multi-agent systems with directed topology.

A basic theoretical analysis is first carried out for the containment control of the second-order multi-agent systems under directed topology without communication time-delay and a sufficient condition is proposed for the achievement of containment control. Based on the above result and frequency-domain analysis method, a sufficient condition is also derived for the achievement of containment control of the second-order multi-agent systems under directed topology with communication time-delays. Finally, simulation results are presented to support the effectiveness of the theoretical results.

For the achievement of containment control of the second-order multi-agent systems under directed topology with communication time-delay, the control gain in the control protocols is completely dependent on the communication topology structure and the maximum of time-delay in the control protocols is dependent on the given control gain and communication topology structure.

The paper investigates the containment control of the second-order multi-agent systems under directed topology with communication time-delays and presents a sufficient conditions for the achievement of containment control. The results and approach proposed in the paper may benefit interesting researchers.

Understandings of house prices and their interrelationships have undoubtedly drawn a great amount of attention from various market participants. This study aims to investigate the monthly newly-built residential house price indices of seventy Chinese cities during a 10-year period spanning January 2011–December 2020 for understandings of issues related to their interdependence and synchronizations.

Analysis here is facilitated through network analysis together with topological and hierarchical characterizations of price comovements.

This study determines eight sectoral groups of cities whose house price indices are directly connected and the price synchronization within each group is higher than that at the national level, although each shows rather idiosyncratic patterns. Degrees of house price comovements are generally lower starting from 2018 at the national level and for the eight sectoral groups. Similarly, this study finds that the synchronization intensity associated with the house price index of each city generally switches to a lower level starting from early 2019.

Results here should be of use to policy design and analysis aiming at housing market evaluations and monitoring.

Information technology-enabled gig platforms connect freelancers with consumers to provide short-term services or asset sharing. The growth of gig economy, however, has been accompanied by controversy, and, recently, food delivery platforms have been criticized for using data-driven techniques to set strict delivery time limits, resulting in negative externality. This study aims to provide managerial implications on the decisions of delivery time and subsidy for food delivery platforms.

The authors develop an analytical framework to investigate the optimal delivery time and subsidy provided to delivery drivers to maximize the gig platform's profit and compare the results with those of a socially optimal outcome.

The study reveals that it is optimal for the platform to shorten the delivery time and raise the subsidy when the food price becomes higher; nevertheless, the platform should shorten the delivery time and lower the subsidy in response to a higher delivery fee. Increases in the food price or delivery fee have non-monotonic effects on the number of fulfilled orders and the platform's profit. In addition, the authors solve the socially optimal outcome and find that a socially optimal delivery time is longer than the platform's preferred length when the delivery fee is high and the negative externality is strong.

The food delivery platform's optimal decision on delivery time is derived after taking negative externality into account, which is rarely considered in the prior literature but is a practically important problem.

Prosocial job characteristics have received the least scholarly attention among the antecedents of employee innovative work behavior (IWB). Hence, antecedents' role remains largely unknown, especially in public sector organizations. Based on the relational job design theory, job characteristics theory (JCT) and public sector innovation literature, the authors examine whether job impact (JI) promotes public sector employees' IWB mediated by work meaningfulness (WM). This study also assesses whether servant leadership (SL) strengthens the influence of JI on IWB (via WM).

The model was examined on a sample of 180 employee-supervisor dyads (90 supervisors and 180 employees) recruited from various government departments in the United Arab Emirates (UAE).

The finding supports the proposed moderated mediation model in which JI enhances IWB. The association between JI and innovative behavior via WM is found to be stronger under high SL behavior.

The authors' findings offer prescriptive insights into SL's crucial role in illustrating when and how JI promotes IWB and offer relevant managerial recommendations for encouraging public sector employees to demonstrate innovative behavior. The authors also provide empirical evidence on the significant contribution of a prosocial job characteristic, i.e. JI, to IWB. In addition to having theoretical and practical significance, the authors' study is aligned with the UAE National Innovation Strategy 2015.