Contact area

Tractive force and train movement stability dependence on division of forces involved in wheel/rail contact area are the main subjects of this article. The influence of wheel/rail contact properties in the vehicle dynamics and adhesion fields is investigated. Current tendency all over the world is to reduce the conicity of wheels with the aim of increasing the speed of trains. Wave-length of moving wheel-set in track for worn wheel-set tyre is twice less than for new wheel running profile.

This study was conducted to predict contact area (A) of bias-ply tire based on contact area index (CAI), inflation pressure (P) and vertical load (W). For this purpose, contact area of four bias-ply tires with different contact area index were measured at three levels of inflation pressure and four levels of vertical load. Results of contact area measurement for bias-ply tires No. 1, 2 and 3 were utilized to determine regression model and three-variable linear regression model A = 113.33-0.0023 CAI-2108.6 P + 33.429 W with R = 0.901 was P 2 obtained. Also, results of contact area measurement for bias-ply tire No. 4 were used to verify model. The paired samples t-test results indicated that the contact area values predicted by model were more than the contact area values measured by test apparatus. To check the discrepancies between the contact area values predicted by model with the contact area values measured by test apparatus, RMSE and MRPD were calculated. The amounts of RMSE and MRPD were 30.4 cm and 33.1%, respectively. Amounts of RMSE and MRPD confirmed 2 that the three-variable linear regression model may be used to predict contact area of bias-ply tire based on contact area index, inflation pressure and vertical load. On the other hand, to calculate actual contact area values or contact area values measured by test apparatus (A) based on contact area values predicted by model M (A) the linear regression model A = 0.920 A-20.08 with R = 0.916 can be strongly recommended. P M P 2

Triboelectric charge accumulation both poses problems and offers opportunities for dry particulate processing. It generates hazards in many industrial systems, but is exploited in several important applications, including electrophotographic toner charging and triboelectric separation. However, the charging of continuous particulate flows on solid surfaces is poorly understood, and design of devices to optimise triboelectric behaviour is often qualitative or based on trial and error. This study attempts to identify the main charging mechanisms for a continuous particulate flow on a flat surface. The proposed charging models incorporate contact time, velocity and mode of contact. A model incorporating contact area effects arising from sliding and rolling contact is consistent with experimental data, as long as a charge limit is imposed on bouncing particles. A mechanism for this charge limit, involving separation discharge, is proposed. The effect of delocalised image charge on the system is estimated and found to be negligible. Some general design principles are proposed for triboelectric optimisation of particle processing devices.Triboelectrification produces hazards and offers opportunities for dry particle processing. Charging mechanisms for a continuous particulate flow on a flat surface are identified and modelled, for sliding, rolling and bouncing contact. These models are then validated using existing experimental data. Some general design principles are proposed for triboelectric optimisation of particle processing devices.

The novel wafer-level packaging (WLP) process described in this paper allows quasi-hermetic capping of optical devices on wafer-level yielding miniaturized glass cavity windows on top of the optical area, at the same time leaving the contact area accessible for standard electrical connections i.e. wire bond. These smaller chip-size optical cavity packages are used within standard chip-on-board (COB) assemblies for high performance optical applications providing high yield and utmost reliability. In this paper the process flow of generating optical cavity glass wafers as well as of the wafer-level capping process is demonstrated and reliability data on wafer-level and package-level are discussed.

The morphological features of lift-off footprints on the aluminium metallization pads were investigated to gain an understanding of the effects of bonding parameters on formation of initial bonds during thermosonic gold ball bonding. The obtained results showed that metallurgical bonding initiated at the peripheral areas of the contact area situated along the direction of ultrasonic vibration. Those areas extended inwards with an increase in ultrasonic power. Both the external bonded area and central non-bonded area increased with increasing bonding force. Based on the evolution of footprints, the bonding models were proposed, and the effects of the bonding parameters on the formation of initial bonds were discussed.

... 1. Introduction. Peanut-induced anaphylaxis remains the dominant and most severe of the immediate hypersensitivity reactions to foods because of its persistency and the life threatening nature (Sampson & McCaskill, 1985). ...

This study is aimed to search the angle optimization of scraping/doctor knife in the drum dryers. Electrical measurements were made via a digital ohmmeter to calculate the real contact area between the drum and doctor knife. It was seen that the electrical resistance was decreased with the increment of drum's load. It's also seen that, the contact resistance between the couple was increased with the increment of temperature. This is an experimental practice; AISI 4140 for a drum material, HSS for a doctor knife were used. So as to increase the hardness and to reduce the resistance, the drum was coated with the harder chromium, and then it was ground for the enhancement of the surface quality.