Papers by Keyword: Buffer

Abstract: Hardfacing weld is a technique which mainly improves and extends the useful life of engineering components. The purpose of this research is to improve welding procedure for one layer and three layers hardfacing of 3.5% Chromium cast steel and to study wear behavior of hardfacing layers. Flux Cored Wire Arc Welding (FCAW) process has been used as a welding process of this research by choosing austenitic stainless steel and martensitic hardfacing wire to weld the buffer and hardfacing layer respectively. Preheating was also used in this study. Abrasive wear test of hardfacing deposit were conducted in accordance with procedure “A” standard of ASTM G65. In addition, microstructures and macrostructure of worn surface deposits were analyzed by using optical microscope. These results showed that there is no crack and defect in the Heat Affected Zone (HAZ) and other regions. The hardness of preheating sample in HAZ regions was lower than the ones without preheating. Therefore, preheating samples should be done before welding. The abrasive wear resistance of three layers hardfacing deposit was better than one layer hardfacing deposit because one layer hardfacing deposit was more diluted from buffer layer than three layers hardfacing deposit. Moreover, weight loss of one hardfacing layer was also higher than three layers.

Abstract: The paper presents a complex quarter car model obtained with ADAMS software, View module, useful in the first stage of suspension dimensioning and optimization.The model is equipped with compression and rebound stopper buffer and suspension trim corrector.The proposed quarter car model with two degrees of freedom (wheel and body) performs all these goals allowing changing:Geometrical elementsPosition of equilibrium, depending on vehicle load;Trim correction;Elastic and dissipative characteristics of the suspension and tire;Suspension stroke;Road profile, assessed either by simple or summation of harmonic functions or reproducing real roadsBuffers (for stroke limitation) position and characteristics;The models developed provide information on:Vertical stability assessed by vertical movements of the body and the longitudinal and transversal stability evaluated based on adherence characterized by wheel ground contact force and frequency of soil detachment wheel.Comfort assessed on the basis of body vertical acceleration and collision forces to the stroke ends.The body-road clearanceThe trim corrector efficiencyAll above performances evaluated function the road unevenness, acceleration, deceleration, turning regime.The damping characteristic is defined by damping forces at different speed for each strokes respectively one for rebound and other for compression.The contact force road-wheel is defined based tire rigidity law.The stopper buffer forces on rebound and compression are defined based each specific rigidity characteristics.The road excitation is realized with a function generator.The software allow the model evolution visualisation in real time, also generating the diagrams of displacements, forces, accelerations, speeds, for each elements or for relative evolution between diverse elements.The simulation was realized for unloaded and fully loaded car using a road generated by a sum of harmonic functions presented in equation (8).The excitation covers the specific frequencies area, being under the body frequencies up to the wheel proper frequencies.The realized ¼ car model, have reached the goal to evaluate the suspension trim correction advantages.The simulations confirm the trim corrector increases the suspension performances, thus for the analyzed case the trim corrector increase simultaneous:Body-ground clearance (evaluated by body higher increasing) between 18.5÷55.1 %Body stability (evaluated by maximal body displacement) between 9.8÷11.4 %Body comfort (evaluated by maximal body acceleration) between 3.4÷35.5 %Adherence (evaluated by maximal and RMS wheel-groundcontact force variation) between 7.0÷12.1 %Body and axles protection (evaluated by buffer strike force) between 10.8÷38.2 %

Abstract: The effect of varying gelatin concentration and temperature on the levelness of wool dyed with 2.0% o.m.f. indigo for various time periods was investigated. The degree of levelness was measured in terms of (RUI)_C values. (RUI)_C stands for corrected relative unlevelness index as reported in the work of Chong et al. [1]. The colour fastness to washing of the indigo-dyed wool using gelatin as a buffer was also determined.Gelatin, used as a buffer, potentially maintained the dyebath pH at a constant value of 10 which consequently reduced the colour variations between dyeings. The levelness of dyeing and depth of shade was found to be unaffected by varying concentrations of gelatin. While longer dyeing times resulted in higher degree of levelness and enhanced shade depths, higher dyeing temperatures did not favour the dyeing of wool with indigo, in that lower shade depths and reduced levelness were achieved. Dyeings of excellent wash fastness and dry and wet rubbing fastness were obtained.

Abstract: The objective of this research is to develop the welding procedure for multilayer hardfacing of 3.5 %chromium cast steel and study wear behavior of hardfacing deposits. Austenitic stainless steel and martensitic hardfacing electrodes were selected as buffer and hardfacing, respectively. Four types of welding procedures were investigated, using shielded metal arc welding (SMAW) process. Three different preheatings were applied in this study. Characteristic of the macro, microstructure and worn surface deposits was investigated by optical microscope. The hardfacing deposits were also determined by the dry sand rubber wheel machine according to procedure A of the ASTM G65 standard. The results indicated that the multilayer hardfacing with and without preheating revealed no crack or defect in the Heat Affected Zone (HAZ) and other regions. The wear resistance of hardfacing presented a little difference. The best abrasive wear resistance was obtained from sample without preheating. This was due to the full martensitic microstructure of the hardfacing.

Abstract: This paper describes a novel device, a wet cell, used for observation in the wet environment inside the scanning electron microscope (SEM). A Wet cell is composed of three counterparts, which are flow control system, thermal system and Wet cell body. The flow system provides continuous buffer liquid to wet cell and maintains cells living at the vacuum environment. It can control different flowrates and switch to different fluidics. Additionally, the thermal system can control the temperature inside the wet cell and maintain at 37 °C. It also offers preheating thermal module to lower the fluctuated of wet cell inside temperature. The wet cell body contains a silicon nitride film based observation window and provides a wet environment for observation between vacuum and anti-vacuum status. In this paper, we introduce the structure and experimental data of flow control and thermal system in Wet cell to let SEM easily provide lots of live imaging information such as dynamics of nano-materials and biological samples in the liquid state.

Abstract: We describe a procedure for the optimization of a 3C-SiC buffer layer for the deposition of 3C-SiC on (001) Si substrates. A 100 – 150 nm thick SiC buffer was deposited after a standard carbonization at 1125 °C, while increasing the temperature from 1125 °C to 1380 °C. Ramp time influenced the quality and the crystallinity of the buffer layer and the presence of voids at the SiC/Si interface. After the optimization of the buffer, to demonstrate its effectiveness, a high-quality 3C-SiC was grown, with excellent surface morphology, crystallinity and low stress.

Abstract: With respect to the application of high-speed, high-resolution A/D converter, the design and implementation of a CMOS input buffer is introduced. The buffer features high-speed and high-linearity. Its performances have been verified in a 14-bit 250MSPS pipelined A/D converter which is developed in 0.18um CMOS-based process technology. The simulation shows that the SFDR of the buffer is up to 104dB at an input clock of 250MHz with an input signal of 25MHz.

Abstract: The article first systematically expounds the working principle and deficiencies of spring buffer, spring - hydraulic buffer, compressible liquid buffer, and other typical buffers. And then detailed introduces the generation, working principle and outstanding features of new material buffer. Finally, according to the characteristic of traditional buffer that performance parameters are immutable, presents a soft mounting buffer that performance parameters can be changed of intelligent, provides theoretic and technological reference of Overhead Weapon Stations for its development design and modification upgrade in China.

Abstract: MAC protocol design in Wireless sensor networks becomes vibrant research field for the past several years. In this paper an EE-Hybrid MAC protocol (Energy efficient hybrid Medium Access Control) has been proposed, which is energy efficient and low latency MAC protocol, which uses interrupt method to assign priority for certain wireless sensor nodes assumed to be present in critical loops of industrial process control domain. EE-Hybrid MAC overcomes some of the limitations in the existing approaches. Industrial wireless sensor network require a suitable MAC protocol which offers energy efficiency and capable of handling emergency situations in industrial automation domain. Time critical and mission critical applications demands not only energy efficiency but strict timeliness and reliability. Harsh environmental condition and dynamic network topologies may cause industrial sensor to malfunction, so the developed protocol must adapt to changing topology and harsh environment. Most of the existing MAC protocols have number of limitations for industrial application domain In industrial automation scenario, certain sensor loops are found to be time critical, where data’s have to be transferred without any further delay. The proposed EE-Hybrid MAC protocol is simulated in NS2 environment, from the result it is observed that proposed protocol provides better performance compared to the conventional MAC protocols.

Abstract: Aircraft landing gear can absorb the energy generated and consumed in aircraft landing, taxiing process, thus weakening the vibration of the aircraft, flight safety plays a vital role. This paper established a landing gear dynamics modeling, its mechanical analysis, and through trial and simulation of the dynamic characteristics of the landing gear were studied, with some practical significance.