จำนวน Repository ( 3611 )

การจำลองและการทดสอบระบบเติมอากาศแบบน้ำไหลเวียนด้วยพลังงานแสงอาทิตย์
การจำลองและการทดสอบระบบเติมอากาศแบบน้ำไหลเวียนด้วยพลังงานแสงอาทิตย์

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.

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การศึกษาผลของกระแสฮาร์มอนิกส์ต่อค่าสูญเสียของหม้อแปลงไฟฟ้าเลื่อนเฟสและการทำให้เป็นจริงด้วยหม้อแปลงไฟฟ้าเลื่อนเฟส 15 องศา
การศึกษาผลของกระแสฮาร์มอนิกส์ต่อค่าสูญเสียของหม้อแปลงไฟฟ้าเลื่อนเฟสและการทำให้เป็นจริงด้วยหม้อแปลงไฟฟ้าเลื่อนเฟส 15 องศา

The trend of energy savings has been widely interested and phase shift transformers (HMT) have been extensively used. This paper presents the investigation of the effect of harmonic currents on losses of the HMT. In this paper a 15-degree HMT with quad secondary winding is applied to find the relationship between harmonic currents and losses of the HMT. This relation can be met by testing the active power of primary and secondary sides while the HMT supplies for two and four non-linear loads at 25% 50% 75% and 100% rated currents respectively. The results reveal that harmonic currents affect winding eddy current losses significantly and the losses for loading the two secondaries 1 and 2 are the same as loading the two secondaries 1 and 3 while both %THDi are different. However for loading the secondaries 1 and 2 the %THDi is more than 15% so it is not met IEEE 519 Std. while the HMT is supplied with four loads the %THDi has met IEEE 519 Std. and the losses are less than 57% compared to one load. As a result of these if the HMT is applied to an adjustable speed drive system it is not only reduced the harmonics but also saved the energies.

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การเพาะเลี้ยงเยื่อเพื่อการขยายพันธุ์และการชักนำเหง้าขนาดเล็กจากว่านชักมดลูกตัวเมีย Curcuma comosa roxb
การเพาะเลี้ยงเยื่อเพื่อการขยายพันธุ์และการชักนำเหง้าขนาดเล็กจากว่านชักมดลูกตัวเมีย Curcuma comosa roxb

This study was conducted to determine the effects of plant growth regulators on in vitro propagated plantlets and microrhizome inductions of Curcuma comosa Roxb. for an efficient development of plant regeneration. In vitro sprouted shoots (2 cm length) of C. comosa were incised in longitudinal section and subcultured on MS media supplemented with 3 mg/L BA for shoot multiplication and plant regeneration. Subsequently the regenerated plants were transferred to MS medium with various concentrations of plant growth regulators; BA (1 3 5 mg/L) kinetin (1 3 5 mg/L) and TDZ (0.5 1 1.5 mg/L). The result showed that MS medium supplemented with 3 mg/L BA was the most effective in shoot induction with the significantly maximum average number of 2.11 shoot buds per responding explant. Moreover MS medium supplemented with 1 mg/L BA produced the longest average of shoot bud explants (12.99 cm) while the basal MS medium induced the longest average of root multiplication (6.63 cm). Furthermore microrhizome induction was produced under in vitro conditions derived young shoot buds upon transfer to MS medium containing various combinations of 1 3 and 5 mg/L BA and 30 60 and 90 g/L sucrose concentrations. The optimum combination in the induction of significantly highest average length of both stem (18.32 cm) and root (7.52 cm) multiplication was obtained on MS basal medium supplemented with 1 mg/L BA and 30 g/L sucrose for 4 weeks. Although microrhizome formation was not produced by the different amount of BA and sucrose in induction medium starch accumulation was found at the base of the stem explants cultured on MS medium containing 60 and 90 g/L sucrose concentrations. Additionally in vitro propagated C. comosa plantlets through microrhizome induction were grown under greenhouse conditions for 4 weeks and further developed into normal plants resulting in successfully high survival rates of 66 – 100% in the cultivated C. comosa.

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การพัฒนาสูตรแป้งซาลาเปาเสริมผลเนื้อลูกตาลสุก
การพัฒนาสูตรแป้งซาลาเปาเสริมผลเนื้อลูกตาลสุก

The results of the using of toddy palm pulp powder form added to steamed buns using ratios of 0 10 20 and 30 %. It was found that from the sensory quality measurements of steamed buns by supplemented toddy palm pulp powder was 10%. As the results of chemical quality analysis of 10% steamed buns by supplemented toddy palm pulp powder was found that the total energy content was 296.25 calories per100g. the moisture ash protein fat and carbohydrate was 39.64 0.69 5.33 5.70 and 55.38 % respectively. The results of physical quality analysis of 10% steamed buns by supplemented toddy palm pulp powder showed that water activity (aw) 77.38 brightness (L*) 10.27 red (a*) 36.25 yellow (b*) 3421.50 respectively Hardness 0.85 g force Springiness 86.25 % Chewiness 1314 g force and Cohesiveness 46.09%. From consumer acceptance testing of 40 testers 90 % of them accepted in this product.

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กำลังและความต้านทานการกัดกร่อนของมอร์ต้าร์ที่ใช้วัสดุประสานกระตุ้นด้วยด่างจากเถ้าถ่านหินแคลเซียมสูง
กำลังและความต้านทานการกัดกร่อนของมอร์ต้าร์ที่ใช้วัสดุประสานกระตุ้นด้วยด่างจากเถ้าถ่านหินแคลเซียมสูง

The aim of this study is developed of alkali activated high calcium fly ash to use as cementitious material to replace Portland cement. The mixture of mortar made from fly ash and sodium hydroxide solution (NaOH) was used to activate strength at concentrations of 2 4 6 and 8 molars. Superplasticizer was used to control the flow of mortar in the rage of 105 – 110. The compressive strength of mortar was determined at 7 28 45 and 60 days. The acid resistance of mortars due to sulfuric at a concentration of 3% were also investigated. The results showed the mortar made from high calcium fly ash with sodium hydroxide of 6 molar obtained the highest compressive strength which could be developed compressive strength up to 189 ksc at 60 days. For the acid resistance of mortar it was found that the of use 6 molar of NaOH activated high calcium fly ash binder had the least weight loss due to sulfuric acid attack.

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