Applied Mechanics and Materials Vols. 789-790

Abstract: This paper presents workpiece surface integrity of micromilling hardened tool steel AISI D2. These include 3D mapping of surface texture, analysis of microstructure and microhardness variation. The results indicate no evidence of major surface damage such as microcracks, un-tempered/over-tempered martensite, phase transformations or white layer formation was detected in any of the specimens analysed. No discernible deformation of the material grain structure beneath the machined surface was observed. This was mainly attributed to the comparatively low levels of mechanical force and temperatures generated during the micro milling operation.

Abstract: Elliptical vibration cutting is a new processing technology of work piece surface texture generation, the technique based on conventional cutting machine main movement and feed motion of the tool, by changing the structure so that the tip motion to generate ellipse trajectory. This paper designed incentive range vibration frequency as 20~40 KHz, can generate elliptical vibration trajectory in the small space of X/Z axis 16um. Tests prove that, the ultrasonic elliptic vibration cutting mechanism improves the specimen surface texture, smooth discharging of chipping, greatly improving the surface finishes of the work piece.

Abstract: The dynamic recrystallization critical strain of this alloy was investigated by Poliak and other scholars using the hardening rate (θ) method; they thought the critical condition corresponded to the inflection point of the lnθ-ε curve and the minimum value on the ∂ (lnθ)/∂ε-ε curve. A dynamic recrystallization critical strain model of 45Cr4NiMoV was established.

Abstract: Coke production is carried out by coal carbonization. The most frequently used coal is anthracite, which features a very low content of volatile substances that not exceed 7%. Current anthracite production is carried out in rotary furnaces, consists of processes as follows: drying, heating, pyrolysis and calcination. Coke cooling is performed in cooling device located at the end of the furnace. To enhance the performance and reduce the specific heat consumption, use of the preheating device for rotary charge was proposed. The charge granulometry allows using the preheating device based on thin layer principle. Proposed solution was verified by simulations.

Abstract: Engineering, stability and orientation of semiconducting molecules are necessary to achieve the high efficiency of multifunctional organic-based devices. Several conjugated molecules facilitate the use of external magnetic fields to tailor both their molecular orientation and electronic properties while being processed for bio or opto-electronic applications. In this work, molecular thin films of vanadyl phthalocynine (VOPc) layers forming conducting channels in organic field-effect transistors were investigated. Three systems based on 100 nm thick VOPc thin film were grown, one in absence of magnetic field, while the other two with parallel and perpendicular to the substrate plane, respectively. Devices were ex-situ investigated by electrical characterization and confocal scanning Raman spectroscopy (SRS). All molecular layers growth on Au electrodes presented enhancement of the Raman signal.

Abstract: The scarcity of conventional fossil fuel, their increasing cost and the detrimental effects of combustion engendered pollutants seems to make alternative sources more appealing. Fish methyl ester is available abundantly. The present experiment assess the performance and emission distinctive of a diesel engine using dissimilar blends of methyl ester of fish, 2-EHN and ethanol with mineral diesel. Methyl ester and diesel additive was blended with diesel in proportions of 20% and 100% by mass and studied under full load conditions. The performance and emission parameters were found to be better than the mineral diesel.

Abstract: This study presents an experimental investigation of CO₂ flowing condensation at the saturation temperature of-10°C, mass flux in the range from 40 to 60kgm^-2s^-1 and vapour quality ranging from 0.2 to 0.8, in a 6.52mm inside diameter horizontal tube. Previous research on refrigerant condensation has shown that under these conditions, CO₂ two phases are expected to develop as a stratified flow. The significant feature of the stratified flow heat transfer is vapour film condensation in the upper region which dominates the overall heat transfer process. Test series in this study confirm that the saturation-to-tube wall temperature difference has a significant influence on the condensing heat transfer coefficient when the temperature difference is within 3K. Comparisons between the experimental results and the predictions by the Dobson, Cavallini and Thome models show that CO₂ stratified flow condensation heat transfer coefficients are over-predicted by these models with mean deviations of 104%, 81% and 127%, respectively.

Abstract: Because of the energy crisis in Pakistan farmers are getting serious difficulties in irrigating their crops under such increasing diesel costs. There is a need to facilitate the farmers in alternative ways of powering their water pumps. There are lots of alternative ways, powering water pump, but most economical way is the solar pumping which can bring great outcomes in Farmers of Pakistan whom are facing serious difficulties in irrigating their crops under such severe energy crisis and ever increasing diesel costs. According to one estimate, In Pakistan more than 1Million pumps are in use, out of which 750,000 are diesel driven pumps. If we replace 25% diesel pumps by solar pumps, we can save about 3570 MW of electricity. In this paper 220 W motor is used to operate two days without sunshine or power from the PV panels, 40Wh was required daily as back up, supply a minimum of 880 Wh. Since this is a 12 V system, 880Wh/12V = 73.3 Ah was employed A battery bank should be at least 73.3 Ah, here, since the controller selected had a deep discharge protection at less than 30% of battery capacity, a bank of at least 105 Ah was required. For this project a 105 Ah battery was used as backup and all the simulation is done in the matlab.

Abstract: Based on a company's production of single shaft circle vibrating screen, we set up the mechanical model of two degrees of freedom and the vibration differential equation to get the natural frequency of the system, and compared with the working frequency of vibrating screen, it can be roughly judged whether the system work normally when resonance occur; And establish the system simulation model by using the method of integral module in the Matlab/Simulink module to get its center of mass in motion. The research results can provide theoretical basis for the design of the screening machine.

Abstract: The paper presents a comparative analysis of existing designs nozzle turbines. The advantages and disadvantages of existing designs nozzles. The description of the new nozzle design for axial microturbines. The analysis of the reasons for reducing the loss of kinetic energy of the flow of the working fluid in the nozzles of the proposed design offers.