Nowadays many robot approaches to robust control problems are applicable only to linear systems for nonlinear systems; we may not be able to easily compute the solution to the optimal control problem as analytical solutions may not be available problem is that statically-stable wheeled mobile robots can easily become dynamically unstable. If the center of gravity is too high or the robot accelerates/decelerates too rapidly or is on a sloping surface so the power supply are necessary for input to actuator robot. This paper presents mode control solutions in power supply for support Omni mobile robot. The performance compare between Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM) in Power supply. The experiment on the 5V/50W 100 KHZ prototype CCM and DCM converter which have been designed and builted with similar circuit layouts and component. Aspects to be compared are stability voltage and ripple factor. The both operation mode are discussed based on the simulation and experimental result.

This research was to influence of electrode force affecting the complete of the resistance spot welding. The specimen was mild steel sheet metal has 1 mm. thickness. Then applied the force to the specimen are 1.0 2.0 3.0 4.0 and 5.0 kN. The welded specimens were tested by tensile shear testing according to JIS Z 3136: 1999 and Macro structure testing according to JIS Z 3139: 1978.The results showed that electrode force had affected on tensile shear and nugget size at 95% confidential (P value > 0.05). The low electrode force had increase the nugget heating because it had a high resistance (Q=I2Rt) and increase the gab between specimen. When the resistance increasing so the current flow will difficult to passed that fusion zone will had a high heating. It will affected to nugget seize heat affected zone and mechanical properties decreasing. The electrode forces are complete 2.0 kN. Tensile shear 6.39 kN and Nugget Size 5.83 mm. This data can be applied to be used as process monitoring of resistance spot weld quality.

This paper presents an establishment of a mathematical model to determine the optimal size of heat pipe (thermosyphon) heat exchanger for reduce the inlet air temperature in evaporative cooling system of greenhouse. The condition of a mathematical model is the total length of heat pipe is 1.5 m. A mathematical model will determine the optimal value of evaporator section and condenser section. The range of evaporator length is 0.5 – 1.4 m with an increment of 0.1 m and condenser length is in range of 0.1 – 1.0 m with an increment of 0.1 m. The inlet air temperature in evaporative cooling of greenhouse is depend on ambient temperature about 35 degree Celsius. While the cooling water temperature is 20 degree Celsius. Evaporative pad of evaporative cooling system is 2 m in width and 7 m in length. From the conditions above the optimize results from a mathematical model are as follows: evaporator section length is 0.9 m and condenser section length is 0.6 m moreover it was shown that investment net saving and maximum heat rate are 79.83 Thousand Baht 0.552 Million Baht and 15.6 kW respectively.

There is a difficulty in using chemical in disinfestations process in organic rice products therefore this research was aimed to study the optimal setting of infrared radiation heating for disinfestations in Organic Hom Mali Rice. Disinfestations process and rice storage were collected by surveying coupled with interviewing the rice milling enterprise. The infrared radiation heating used in this experiment was belt type with lamp power of 1000 watt. In this study Design of experimental technique was applied to generate the optimum setting of the infrared heating process. The experiments generated by Box Behnken design were 15 experiments and 2 replicate times therefore the total experiments were 30 times. The 3 factors include heating temperature gap between rice and infrared lamp and rice layer thickness. The result from statistical data analysis at reliability level of 95 % shown that the optimization value were heating temperature of 70 oC height of lamp above rice of 10 cm. and rice thickness of 0.5 cm insects mortality rate within 2-3 minutes. Rice after heating were subjected to naturally slow cooling by air therefore rice quality in a good condition without broken or cracking.

The aim of this research is to paint silk fabric with batik technique using five natural dyes from margosa bark lac mango leaves marigold and otaheite gooseberry bark. The pre-mordant and after-mordant techniques were used in this work. Ten mordants Aluminum potassium sulphate Copper (II) sulphate Sodium dichromate Tannic acid Tartaric acid Tin (II) chloride and Calcium acetate-monohydrate were applied. The batik fabrics were characterized in color strength rubbing fastness washing fastness light fastness and stiffness. The result indicated that silk fabric painted with natural dye from margosa bark could use all 10 mordants to improve color strength and gave various shades of color. The silk fabric painted with natural dye from lac could not use all 10 mordants to improve color strength but it gave various shade. The silk fabric painted with natural dye from mango leaves marigold and otaheite gooseberry bark showed that almost 10 mordants gave higher color strength and various shade. The mordanting technique would give good fastness and reduce the stiffness of batik fabric.