Search results

For moderate pressure and high pressure gear pumps, the temperature failure problem of bearings is now of considerable concern because of their heavy loads. However, the compact structure and the efficiency consideration make it extremely difficult to improve the bearing cooling. A self-circulating oil bearing system is developed for gear pumps with self-lubricating bearings to solve this problem. The oil is aspirated in from the low pressure chamber of the gear pump and discharged to the same chamber by using the pressure difference in the journal bearing, thus achieving the self-circulation.

An experiment test rig has been built for the feasibility study. The oil flow rate under different speeds has been recorded. Furthermore, the temperatures of the bearings with or without the oil circulation have been compared. Additionally, the oil flow in the test rig has been simulated using computational fluid dynamics codes.

The experimental and numerical results agree well. The experimental results indicate that the oil flow rate increases approximately linearly with the speed and the bearing temperature can be lowered successfully. The calculation results indicate that the bearing load capacity is nearly the same. Both the experimental and numerical studies establish that the self-circulating oil bearing system works successfully.

As far as the authors know, it is the first time to find that the self-circulation can be built using the pressure difference in the bearing oil film, and this principle can be applied in the cooling and lubrication of the gear pumps to solve the temperature failure problem.

Using social network theory (SNT), this study empirically examines the impact of digital supply chain announcements disclosing corporate social responsibility (CSR) information on stock market value.

Based on 172 digital supply chain announcements disclosing CSR information from Chinese A-share listed companies, this study uses event study method to test the hypotheses.

First, digital supply chain announcements disclosing CSR information generate positive and significant market reactions, which is timely. Second, strategic CSR and value-based CSR disclosed in digital supply chain announcements have a more positive impact on stock market, however there is no significant difference when the CSR orientation is either towards internal or external stakeholders. Third, in terms of digital supply chain network characteristics, announcements reflecting higher relationship embeddedness and higher digital breadth and depth lead to more positive increases of stock value.

First, the authors consider the value of CSR information in digital supply chain announcements, using an event study approach to fill the gap in the related area. This study is the first examination of the joint impact of digital supply chain and CSR on market reactions. Second, compared to the previous studies on the single dimension of digital supply chain technology application, the authors innovatively consider supply chain network relationship and network structure based on social network theory and integrate several factors that may affect the market reaction. This study improves the understanding of the mechanism between digital supply chain announcements disclosing CSR information and stock market, and informs future research.

This report is the result of a five‐month survey of information provision in the London Borough of Islington. It looks at information on learning opportunities for adults and complements Brenda Neale's survey of adult learner needs which identified a lack of accessible information as a major barrier for adults in the Borough wishing to return to learning.

The term success in this paper is measured by the yardstick of both material and non‐material ones. This study attempts to examine the success story behind Malaysia's development with evidences drawn from both the conventionally used criteria together with the Islamically motivated universal values and ethos. Of the conventional factors, political consolidation of the first Prime Minister in the presence of dynamic enterprising ability of the Chinese as well as South Indian Community based on family values played a pivotal role in creating a foundation for development. The majority Malays, on the other hand, being the victim of colonial legacies and multi‐farious historical phenomenon were by‐passed. Subsequently, the big bargain of 1957, the year of independence by way of securing Malay special rights in the constitution laid the foundation for new strategy of development based on distributive justice. The New Economic Policy with the twin objetives of eradicating poverty and restructuring society could not have been implemented in the absence of universal values such as loyalty, tolerance, sympathy, caring and sharing being demonstrated by all the races regardless of socio‐economic and political superiority. This paper thus argues that from the very beginning the committed and pragmatic leadership, policy continuation, policy dynamism and policy flexibility, among many others, acted as a catalyst for the success story behind Malaysia's development.

Traditional prediction of braking characteristics of vehicular hydrodynamic retarders is commonly conducted based on braking characteristics model of closed working chamber, namely, closed working chamber model (CWCM). In CWCM, inlet and outlet oil pressures and braking torque are considered to be independent of inlet and outlet flow rates. However, inlet and outlet flow rates can affect internal and external braking characteristics under actual working conditions. This study aims to establish a more accurate braking characteristics model of a hydrodynamic retarder under full oil-charging condition, and then the influence of varying inlet and outlet flow rates on oil pressures and braking torque is investigated in this paper.

A full flow passage of working chamber in a hydrodynamic retarder with inlet and outlets was established, and the reliability of numerical model was analyzed and validated. Pressure rise was introduced to describe the variation of inlet and outlet oil pressures. Then, on the basis of the validation, the CWCM was proposed at different rotor rotational speeds. The inlet and outlet oil pressures and braking torque were numerically computed at different inlet and outlet flow rates with Full Factorial Design experimental method. The results obtained were involved into establishing the braking characteristics model of open working chamber, namely, open working chamber model (OWCM), combined with Radial basis function approximation model. The OWCM with different inlet and outlet flow rates was analyzed and compared with CWCM.

The results show that inlet and outlet flow rates have obvious influence on the variation of inlet and outlet oil pressures in OWCM compared with CWCM. The outlet A pressure rise significantly changes with the inlet and outlet A flow rates, while the pressure rise of outlet B is mainly affected by the outlet B flow rate.

This paper presents an OWCM of hydrodynamic retarders under full oil-charging condition. The model takes into account the impact of oil inflowing and outflowing from the working chamber, which can provide a more accurate prediction of braking characteristics of hydrodynamic retarders.

Starting from the theoretical mechanism of profit sharing between finance and the real economy, this paper reviews and analyzes the profitability of China's banking industry and makes a horizontal comparison with the banking industry of the United States, Japan, and Germany.

Based on the panel threshold model, it is found that there is a dual-threshold asymmetric effect between banking profit and the growth of real economy. When the net profit rate of the banking industry is lower than 0.491%, the increase in banking profitability will inhibit the growth of real economy due to profit grabbing; when the rate falls within the range of 0.491–0.801%, the increase in bank profitability is conducive to the growth of real economy.

Finance and the real economy are in the most comfortable symbiotic state; when the rate is higher than 0.801%, the continued increase in bank profitability will weaken the promotion effect of finance on the real economy, but bank profitability and the growth of real economy are still in a symbiotic state of positive promotion.

The promotion effect of China's bank profitability to the growth of real economy has shifted from the suboptimal state to the optimal range as a whole, which is attributed to the strong deleveraging and strict supervision of the Chinese government after 2016, the timely and decisive “stepping on the brakes”, pulling the financial sector back from the “illusion” caused by “self-circulated” profits and preventing it from harming the real economy.

The lubrication of the high-speed reducer of an electric vehicle is investigated. The specific contents include visualization of the flow field inside reducer, lubrication evaluation of bearings and efficiency experiment.

The flow field inside reducer at five working conditions: straight, uphill, downhill, left lean and right lean is simulated by smoothed particle hydrodynamics (SPH). According to the instantaneous number of particles through bearings, the lubrication states of bearings are evaluated. The test platform is set up to measure the efficiency of the reducer.

The flow field inside the reducer is obtained, the lubrication of bearings needs to be improved, the efficiency of the electric vehicle reducer meets the requirement.

The SPH method is used to simulate lubrication instead of using the traditional grid-based finite volume method. A novel method to evaluate the lubrication of bearings is proposed. The method and conclusions can guide electric vehicle reducer design.

The purpose of this paper is to discuss the combined effects of the deterministic surface roughness and porous structure on the lubrication property of the multi-layer bearing.

Digital filtering technique and Kozeny-Carman equation are used to simulate the random Gauss surface and the internal pore structure of the porous bearing, respectively. Effects of surface morphology, structure and pores on the lubrication property are discussed by using the finite difference method.

Results show that the lubrication performance of the multi-layer bearing increased with the increase of the surface roughness. Also, the transverse surface is better than that of the longitudinal surface. Moreover, lubricating property is getting worse with the increase of the height of each layer and the porosity. The lower permeability surface is beneficial to improve the lubrication performance when the total porosity is certain.

The effect of the Gauss roughness parameters on the detail of lubrication performance are analysed, such as the migration of the oil film rupture point position, the expansion of the pressure distribution region and the fluctuation of the pressure distribution curve with the roughness parameters. The combined effects of surface roughness, multi-layer structure and the internal pore parameters on the hydrodynamic behaviours of multi-layer porous bearing are analysed. This work is beneficial for the analysis of the tribological property and the structural design of multi-layer bearing.

The purpose of this study is to investigate lubricant film-forming capability of oil-impregnated sintered material in highly loaded non-conformal contacts. This self-lubrication mechanism is well described in lightly loaded conformal contacts such as journal bearings; however, only a little has been published about the application to highly loaded contacts under elastohydrodynamic lubrication regime (EHL).

Thin film colorimetric interferometry is used to describe the effect of different operating conditions on lubricant film formation in line contacts.

Under fully flooded conditions, the effect of porous structure can be mainly traced back to the different elastic properties. When the contact is lubricated only by oil bleeding from the oil-impregnated sintered material, starvation is likely to occur. It is indicated that lubricant film thickness is mainly governed by oil bleeding capacity. The relationship between oil starvation parameters corresponds well with classic starved EHL theory.

To show practical, relevant limitations of the considered self-lubrication system, time tests were conducted. The findings indicate that EHL contact with oil-impregnated sintered material may provide about 40 per cent of fully flooded film thickness.

For the first time, the paper presents results on the EHL film-forming capability of oil-impregnated sintered material by measuring the lubricant film thickness directly. The present paper identifies the phenomena involved, which is necessary for the understanding of the behavior of this complex tribological system.