Susilo Adi Widyanto

Polyvinilidine fluoride (PVDF) nanofiber membrane for Li-ion rechargeable battery separator

This study reported synthesis and characterization of PVDF (polyvinilidine fluoride) nanofiber membrane using electrospinning method for Li-ion rechargeable battery separator. Electrospinning equipment system consists of a DC high voltage (HV - DC), a controllable spinner and a plate collector. The effects of the applied voltage on morphological property, porosity and thermal property were systematically investigated. The application of DC voltage at a range of 13 to 17 kV resulted the one-dimension nanostructure of the PVdF nanofiber. The produced PVdF nanofiber membrane separators are evaluated to have a higher level of porosity (86 – 93%) and a good thermal shrinkage property in comparison to Polypropylene (PP) microporous membrane separator. The produced PVdF membrane separators were assembled into the LiFePO4 cells and demonstrated high charge-discharge capacities at room temperature with the coulombic efficiency reaching 80 %.

Error Analysis of ON-OFF and ANN Controllers Based on Evapotranspiration

The changing of climate directly affects on decreasing agricultural production. Therefore, application of automated system in agriculture activities is potential issue which must be considered. This paper presents error analysis of ON-OFF and ANN controllers which are applied to the automated irrigation system. Controlling of irrigation system used a calculated Penman-Monteith evapotranspiration and a reference of soil moisture as the compared input. Input parameters of the evapotranspiration included temperature, heat radiation, atmosphere pressure and wind speed. The performance of such controllers were evaluated and compared based on error of both controllers. The simulation result of ONOFF controller was used as the reference of controller development based on ATmega 8 microcontroller. The simulation results show that the error of the ON-OFF controller can be adjusted by setting the sampling time of the dead zone discretization. Error of the ON-OFF controller with sampling time of 0.05 second is equal to the error of ANN controller; these are 14.3% of the reference of signal amplitude.

Surface Roughness Identification of Cutting Product on Design Aspect Variation of Modular Axis Mechanism

The use of modular component in machine tool structure is an attempt to reduce the production cost. This paper presents the development of machine tool structure for low cutting force using the modular axis mechanism. Single axis mechanism was designed and varied the mover bearing, the length of slideway and the diameter of lead-screw. Cutting test was then performed using the variation. The experimental result shows that the dimension tolerance of linear bearing is the dominant aspect which affect on the product surface roughness. While the use of ball bearing in mover system, the motion looseness can be minimized affects on improving product surface finish.

Evaluation of the Effect of Application of Air Jet Cooling and Cooled-Air Jet Cooling on Machining Characteristics of St 60 Steel

The use of cutting fluid is to reduce the friction between tool and workpiece, reduce and dissipate generated heat. The application of cutting fluid is also to improve the surface quality of workpiece and increase the tool life. On the other side, cutting fluid contains chemical carcinogens that causes serious health risks for machine operators and have inherent waste disposal concern on the environment. Due to these problems, some alternative have been sought to minimize or avoid the use of cutting fluid in machining processes. Air cooling techniques were proposed as alternative cooling mediums, i.e air jet cooling (AJC) and cooled-air jet cooling (CAJC), the liquid less method. In this work, air cooling techniques were investigated to be a possible solution of machining problem for cooling medium. This studi was also motivated by economics point of view that the application of AJC and CAJC would be more efficient than liquid method. The purpose of this study is to investigate the effect of AJC and CAJC on turning process of St 60 steel because it is used widely for production of components especially in small and medium enterprises in Indonesia. The tool tip temperatures, surface roughness and tool wear were measured for a range of cutting times. For a comparison purposes, experiments were also carried out with using traditional liquid coolant and without any cooling applied to the tool tip (dry cutting method). Experiments have shown that air cooling technques (AJC, and CAJC) can be used as cooling medium in machining process. Experimental results show that machining with CAJC have shorter tool life compare to machining with AJC and dry cutting, but liquid coolant in this studi is still the best cooling medium for machining of St 60 steel..