Microstructural analysis and multi response optimization of WEDM of Inconel 825 using RSM based desirability approach

Increasing demand of aerospace industry for more heat resistant and tough material have open up the possibility of the use of Inconel 825 for making of combustor casing and turbine blades. Because of its robust nature, Inconel 825 is a difficult-to-cut material with conventional methods. Wire-cut electrical discharge machining (WEDM), a non traditional method uses thermoelectric erosion principle to produce intricate shape and profiles of such difficult-to-cut material. In this study, various operating parameters of WEDM are optimized using desirability approach and microstructural behavior at optimum combinations was studied. Input parameters viz. pulse-on time, pulse-off time, peak current, spark gap voltage, wire tension, wire feed and performance has been measured in term of material removal rate, surface roughness and wire wear ratio. It has been observed that at 110 machine unit pulse-on time (Ton), 35 machine unit pulse-off time (Toff), 46 volt gap voltage (SV), 120 ampere peak current (IP), 11 machine unit wire tension (WT) and 5 m/min wire feed (WF), the values obtained for material removal rate (MRR), surface roughness (SR) and wire wear ratio (WWR) were 27.691mm2/min, 2.721 μmand 0.117 respectively. Scanning electron microscopy, energy dispersive spectrograph and X-ray diffraction analysis has also been carried out to study the surface characterization. Comparatively less numbers of cracks, pockmarks, craters, and pulled out material were found on work specimen surface and wire electrode surface under standardized conditions, thus maintaining the surface integrity of the machined surface.

CARDIORESPIRATORY SYSTEM UNDER BICYCLE ERGOMETER TEST IN SKIERS WITH DIFFERENT TRAINING STATUS (KOMI REPUBLIC)

The aim of the study is to examine the impact of training status on ski racers (Komi Republic) at rest and under bicycle ergometry evaluating their cardiorespiratory system parameters. Materials and Methods. The authors examined male ski racers with different training status: 22 first-rank sportsmen, 22 candidates for Master of Sports and 22 Masters of Sports. Athletes underwent bicycle ergometry loads up to refusal. Oxycon Pro system (Germany) was used. Then authors studied the complex of cardiorespiratory parameters, calculating maximum oxygen consumption and unit physiological cost. Results. At rest and under standard physical load (200 W) Masters of Sports demonstrate significantly increased training status among ski racers in such cardiorespiratory system parameters as heart rate, rate pressure product and oxygen pulse. Under standard physical load (200 W) statistically significant differences between first-rank sportsmen and candidates for Master of Sports are detected by heart rate, rate pressure product, respiration rate, respiratory minute volume and oxygen utilization coefficient. Such deviations indicate differences in training status. Under maximum load, the highest training status is found in Masters of Sports: bicycle ergometry load power and duration; unit pulse, pressor and cardiac cost, bulk and unit values of maximum oxygen consumption. Heart rate values, unit pulse and heart-vent cost indicate a high training status in candidates for Master of Sports under load up to refusal, if compared with first-rank sportsmen. Athletes’ organism under load up to refusal works more efficiently than under moderate load (200 W). The training status in ski racers (Komi Republic) is manifested in the saving cardiorespiratory system functions, both at rest and under standard bicycle ergometry, as well as in parameters of unit physiological cost under loads up to refusal and increased values of maximum oxygen consumption. Keywords: ski racers, Komi Republic, training status, bicycle ergometry loads, cardiorespiratory system, maximum oxygen consumption.

A Kind of Intelligent Fast Charger of the Lead Acid Battery Based on MCU

Based on pulse fast charge of the lead acid battery, this paper designed a kind of intelligent battery charger, including mainly a minimum system of 16 bit MCU as intelligent center, the constant resistance discharge unit to complete SOC prediction and duty cycle of the pulse charging waveform, the voltage-current-temperature measurement unit, pulse charging control unit. The duty cycle of this charger agreed with SOC of the battery, then using short floating charge in the later stage, thus greatly optimizing the pulse charging mode. Finally, compared with the conventional constant voltage and constant current charging, the charger greatly reduced the charging time.

The Pumping Parameters for Er-Doped Tellurite Glass

Erbium doped tellurite glass rod of the 78.5 TeO2 20 ZnO 1.5 Er2O3 where has successfully been fabricated as lasing medium and have been investigated by means of their properties needed in lasing application. The external triggering method is used to generate high peak current in several microsecond pulse duration. The external triggering circuit design consists of power supply, discharge capacitor, control unit, pulse forming network and ignition circuit. This driver operates in single mode pulse that can be adjusted corresponding to the controller which can vary from 650V to 1000V. The operation is started initially with an external trigger pulse which is the voltage pulse of 8kV with pulse duration 20.0μs. The connection operated by trigger thrystor (SCR) as a switch and ionized gaseous inside the lamp. After the gaseous breakdown, the current from the capacitor flows continuously through the flashlamp. The output current is initially increased proportion in order to the input energy. Maximum value of peak current flashing at 888A with higher input energy, while, the increasing voltage is not linearly increased with the input energy. From the plotted graph of current and voltage, V-I, shows a nonlinear relationship with the electrical input energy. The developed flashlamp driver has produced about 87% in efficiency while another 13% is lost in the circuit resistance. Flashlamp radiation is detected by using spectrometer in the range of 200nm to 1000nm. The beam is used to excite the erbium glass medium and a coherent beam of 1550nm wavelength is produced.