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The aim of this work is to reveal the temperature rise characteristics of the new designed disc during a braking process. In underground coal mines, the highest temperature of the disc brake used for inclined downward belt conveyors should be < 150 to prevent gas explosion during a braking process. To meet the requirements, a new type of disc was designed.

By using ANSYS software, the disc surface and interior temperature rise variations, effect of braking time and running speed on temperature rise are analyzed numerically.

The results show that the new designed disc can meet the coal mines’ requirements well, during the braking process the disc surface temperature increases at first and then decreases, there is an obvious temperature gradient in the axial direction; when running speed increases to two times of the rated one, the highest temperature nearly reaches 150; and a prolonged braking time can decrease the highest temperature effectively.

It indicates that the disc brake should act as earlier as possible to slow down the belt conveyor when overspeed occurs; and when the running speed increases to two times of the rated one, the braking time must be prolonged to prevent gas explosion.

Research findings of this paper provides theoretical basis for the practical applications of the disc brake used for inclined downward belt conveyor.

Rotary disc is a key component in the compact spherical pump, connecting shaft and piston, bearing hydraulic force conformally and constituting dynamic working chambers alternatively. Motion of rotary disc comprises two components. One is rotating around its own axis and the other is sliding on a cone surface. Therefore, it is necessary to investigate the friction and wear mechanism between rotary disc and cylinder under a complicated operation condition.

Structural properties of rotary disc are analyzed first. Frictional moment of rotary disc is modeled based on its structural characteristics and working mechanism, and the constraints of the structural parameters are considered. Besides, the concept of dimensionless contact area is proposed. Comparison is performed between the proposed concept and the frictional moment to determine an optimized beginning angle for spherical pump with a given displacement. The wear model of rotary disc is also established based on its kinematic property, a velocity coefficient is proposed and its common values are presented.

Effects of structural parameters, i.e. beginning angle and ending angle on the frictional moment, are obtained quantitatively. The frictional moment increases with beginning and ending angle with different rates. While the dimensionless contact area decreases with beginning angle. The larger the piston angle, the larger the velocity coefficient will be. The rotary disc wears severely with a larger beginning angle and smaller ending angle, while it has the smallest wear rate under a smaller beginning angle and a larger ending angle.

The originality lies in modeling the complex contact force of rotary disc based on its specific structure. These conclusions can be used to optimize the structural parameters of rotary disc.

Several systems, ranging in price from about $30 000 to over $200 000, are now available to aid database publishers and other organizations in disseminating information products on CD‐ROM media.

Examines recent studies of maximum expected disc life and the implications for archive storage on CD‐ROM. Discusses the manufacture and structure of compact discs, the phenomenon of disc rot, how discs can be ruined in use, and some actions which can reduce the risk of damage to compact discs. Concludes that when CD becomes a widespread archival medium, they will have to be treated as carefully as other media, although the problem of disc rot is beyond the purchasers′ control.

A mathematical model has been developed to predict steady state creep response of a rotating disc made of SiC (particle/whisker) reinforced 6061Al matrix composite. The model is used to investigate the effect of SiC morphology on the creep behavior of composite disc. The steady state creep behavior has been described by Sherby’s creep law. The creep stresses and creep rates are significantly affected by the morphology of SiC. The steady state creep rates in whisker reinforced disc are observed to be significantly lower than those observed in particle reinforced disc.

As CDROMs become a mass medium for entertainment and reference, the prices of CDROM discs have been dropping while the speed of CDROM drives has been increasing. For example, Essex Entertainment is now marketing 50 CDROM titles through music, book and budget retail stores at $9.95 per disc. Two years ago, the street price of single‐speed single‐disc CDROM drives was in the range of $200–400. Today, a similar drive that runs four times as fast (quad‐speed) can be purchased for about the same price. Meanwhile, sextuple‐speed drives are already available and there is no indication that the limits of CDROM drive speed have as yet been reached. This article discusses both quad‐speed and sextuple‐speed CDROM disc drives, and it also takes note of the many types of multiple disc drives that are being offered — some able to deploy hundreds of CDROM discs for almost instant use by equally large numbers of users.

This article examines the sensitivity of U.S. exports to the availability of export incentives offered under the Domestic International Sales Corporation (DISC) and the Foreign Sales Corporation (FSC) provisions of U.S. tax law. Evidence on the efficacy of export tax incentives is mixed. The history of the DISC/FSC tax incentives provides a natural experiment to address the question of the effect of tax incentives on export volume. We examine the relation of U.S. export volume to the availability of these export tax incentives from 1967 to 1998, controlling for product class and important macroeconomic variables, and find evidence of a positive association between the level of U.S. exports and the existence of the export incentives offered under the DISC/FSC provisions. However, this association depends on product type. Our findings using actual export data are independent of otherwise available data demonstrating a general growth in the use of DISC/FSC entities and the sales volume of these entities. The latter data suffer from an interpretation problem because changes in the number of special export entities used and their sales volume do not necessarily correlate with changes in actual export levels over time. The approach we use in this study is an attempt to overcome this limitation. The reported results have implications for both tax policy regarding the design of export tax incentives and the European Union’s claim that U.S. export tax incentives have damaged U.S. competitors in foreign trade.

This study aims to clarify the relationship between the coefficient of friction (COF) and temperature of aluminum-based brake discs.

Three friction blocks with different COFs are examined by a TM-I-type reduced-scale inertial braking dynamometer. On this basis, the thermo-mechanically coupled model of friction pairs is established to study the evolution of brake disc temperature under different COFs using ADINA software.

Results indicate that the calculated disc temperature field matches the experimental well. The effect of COF on the peak temperature is magnified by the braking speed. With the COF increasing, the rise rate of instantaneous peak temperature is accelerated, and the dynamic equilibrium period and cooling-down period are observed in advance. The increase in COF promotes the area ratio of the high-temperature zone and the maximum radial temperature difference. When the COF is increased from 0.245 to 0.359 and 0.434 at 140 km/h, the area ratio of high-temperature zone increases from 12% to 44% and 49% and the maximum radial temperature difference increases from 56°C to 75°C and 83°C. The sensitiveness of the axial temperature difference to the COF is related to the braking time. The maximum axial temperature difference increases with COF in the early stages of braking, while it is hardly sensitive to the COF in the later stages of braking.

The effect of COF on the aluminum-based brake disc temperature is revealed, providing a theoretical reference for the popularization of aluminum-based brake discs and the selection of matching brake pads.

The purpose of this paper is to examine the practicability of the self-designed ambient humidity controllable pin-disc/rolling multifunctional friction and wear test device and to evaluate the friction and wear characteristics of materials under diverse ambient humidity conditions in different contact forms.

The practicability of the self-designed multifunctional friction tester was examined by the friction and wear tests of materials under different ambient humidity conditions [65%RH, 98%RH (relative humidity)] in diverse contact forms (pin/disc and rolling). Meanwhile, the friction and wear properties of pin/disc samples also rolling samples were assessed from three aspects: average friction coefficient, wear mass and wear morphology.

The results prove that the self-designed multifunctional friction tester has practicability. Therefore, it can be used to simulate the friction and wear tests of materials under diverse ambient humidity conditions in different contact forms. Besides, it is evident that the wear damage of pin/disc and rolling samples are greatly improved under high ambient humidity conditions. And when other conditions are identical, the higher the ambient humidity, the smaller the average friction coefficient, wear mass and wear damage degree of pin/disc also rolling samples.

This paper offers a self-designed multifunctional friction and wear test device. And the tester not only can realize the control of test ambient humidity, but also achieve the wear test of pin/disc or rolling contact forms. The design and production of the tester can offer convenience for the research of tribology, and provide fundamental guidance for the study of materials under high humidity condition in diverse contact forms.

The purpose of this paper is to study the influence of braking speed at –20 °C on the wear property of high-speed railway braking materials and the temperature also stress analyses of brake disc friction surface.

Friction brake tester was used to simulate the wear test of high-speed railway braking materials at diverse braking speeds (2,100, 2,400, 2,700 and 3,000 rad/min) at –20 °C and the stress and temperature analyses of brake disc friction surface were carried out by COMSOL.

Compared with 20°C, there is initial stress of brake disc friction surface before brake starting; also, the maximum wear depth is larger at –20°C. Besides, at –20 °C, with the rising of braking speed, the graphite particles on the friction surface of brake pad significantly reduce. And scratches and cracks are formed on brake pad friction surface. Besides, the abrasive wear, adhesive wear and thermal cracks of brake disc friction surface are aggravated. Moreover, the maximal worn depth also increase. Meanwhile, the highest temperature and the maximum thermal stress of brake disc friction surface both raise. Furthermore, the temperature and thermal stress gradients at radial direction of brake disc friction surface aggrandize, which makes the thermal cracks on brake disc friction surface further exacerbated.

In this paper, the wear property of the high-speed railway braking materials is studied by combining experiment and simulation. However, due to the low-speed traveling of high-speed railway was mainly studied in this paper, there may be no comprehensive simulation of the real running condition of high-speed railway. At the same time, the working condition of low-temperature environment cannot be completely simulated and controlled.

The research results of this paper provide a basic instruction for other researchers and also provide an important reference for relevant personnel to choose the braking speed of high-speed railway at –20 °C.

The research of this paper provides a brick for the study of high-speed railway braking materials and also provides some references for the safe service of trains in low-temperature environment.

This paper studied the wear property and carried out the simulation analysis of braking materials at –20 °C at diverse braking speed. The research findings provide an important reference for the selection of braking speed of high-speed railway at –20 °C.