The amount of dissolved oxygen (DO) in aquaculture ponds is considered to be one of the most important aspects for the survival of fishes. The water in aquaculture ponds is stratified into distinct layers with different DO caused by differences in temperature. This temperature difference occurs when the surface layer of water heated by the sun becomes hotter than the lower water layer. Since the top layer is in contact with the air it contains the most DO. On the other hand the deepest layer is isolated from the air it contains the lowest amount of DO. This study proposed an aeration system called a Solar Circulating-Water Aeration System (SCWAS). The SCWAS uses solar thermal energy to create a natural water circulation. In other words it provides an upward current of water from the bottom to the pond surface and a downward current from the surface to the bottom. This circulation creates the movement of surface water and then increases the DO content of the surface water. This water circulation moves highly oxygenated surface water to the bottom layer forcing low oxygen water from the bottom up to the surface where it can absorb oxygen. To evaluate this design concept the numerical simulations of the system were conducted using ANSYS Fluent software. According to the simulation results the SCWAS can provide the natural water circulation. It was found that a flow rate of 2.24 L/s is obtained when the ratio between the draft tube inlet (r) the draft tube outlet (R) the base (L) is 1: 2: 3. In addition an SCWAS prototype was built and installed in a tilapia aquaculture system. A calibrated measuring system was installed to investigate the prototype performance. The experimental results indicate that the average DO values at the water surface and at the bottom of the pond increased by 1.45 and 1.40 times respectively compared with those of a pond without SCWAS. Economic analysis shows that the payback period of SCWAS is 4.58 years and its investment cost is 17.49% less than that of the paddle-wheel aerator.

This research is to test the fatigue endurance of the material by using end bending of specimen. The testing material is S45C steel and forming to the standard size for testing. The specimens with a diameter of 8 mm required a different bending moment. It was found that the large bending moment affects the fatigue of the specimen. The specimen quickly damaged due to the high bending stress and there were a small number of load cycles. If the bending moment acting on the specimen was reduced to the bending stress decreased and the number of load cycles increasing. It was shown that the bending stress and the magnitude of the bending moment affected the fatigue of the material. Also the appearance of damage marks of the specimen will have a flaw around the fracture surface. Then the flaw will be enlarged until the specimen will be damaged by fracture.

The objective of this research is to construct a phased array device to be able to inspect all sizes of welded pipes and to study materials suitable for creating a phased array. The results obtained from testing both materials are PLA plastics carbon fiber. In order to obtain the force exerted on the material and the intensity of the force exerted on the same material it is found that the strength of the comparison between the two materials is different from the PLA plastic test. Of carbon fibers will be strong and lighter than plastic. Result from the test for Elastic In the impact and strength tests of both materials it can be used to examine pipes with a circumference of 50 centimeters to 100 centimeters and to use a 34 mm. length phased array probe with a width of 24.6 mm. 36 degrees angle and then adjust the strap as needed to reduce the steps during the use of inspection equipment.

This study applied the kunzelstab penetration Test (KPT) or Light Penetrometer to examined penetration resistance values geological profiles and estimate shear strength properties of soils. KPT tests were carried out on steep slopes that exhibit potential slope movement in Chiang Rai province. The principal uses of the KPT are examined; i.e. correction method for N’KPT’ soil profile and allowable bearing capacity of soil foundation. KPT tests were conducted at 13 boreholes each measuring 4.00 m long along the crown of the slope. The results indicated the compacted layer and located the firm layer of soil foundation. The average allowable bearing capacities were 1.53 t/m2 at depth of 1.00-5.00 m and 17.06 t/m2 for 5.00-6.00 m depth respectively. Furthermore this paper presents an analysis of the stability of a slope with the shear strength parameters of the soil and the geological profile were defined based on the results of KPT. The results of factor of safety were below the stable value for analysis cases with groundwater table. Test results demonstrate the usefulness of the KPT method in geotechnical investigations to estimate soil profile and bearing capacity efficiently and economically. This approach is also less time consuming compared to other geotechnical site investigation methods.

The aim of this work was to validate the sample preparation using a microwave digestion for determination of total arsenic in a spiked soil. Graphite fernace atomic absorbtion spectrophotometer (GFAAS) technique was used to determine the total arsenic using palladium nitrate Pd(NO3)3 as a modifier agent. The instrumental detection was performed under the condition steps of drying ashing atomizing and cleaning to be 100 1200 2250 and 2600 C. The external calibration curve was constructed using the automatic program based on the master standard of arsenic with 20 ppb. It was found that linearity range was in the range of 1 to 20 ppb with R2>0.999. Based on microwave digestion condition the sample preparation with and without HF was also compared the total arsenic in the spiked soil with a 10 ppb. The result shoewd that the arsenic content obtained fron the prearation with and without HF did not significantly diferent at the 95% confidence limit. The recovery was 80.3 and 82.3% for the spiked sample with 2.5 and 10 ppb respectively. The relative standard deviation was 2.15% (n=11). The results of this work can also confirmed that the preparation method using microwave digestion provided the more advantages such as rapid a little volume of reagents completely digestion.