จำนวน Repository ( 3447 )
นวัตกรรมคอนกรีตต้นทุนต่ำไหลเข้าแบบง่ายโดยการใช้เถ้าทิ่้ง
This research presents a study of the compressive strength porosity chloride penetration resistance to carbonation and corrosion of self-compacting concrete containing fly ash ground rice husk-bark ash and ground bottom ash. Portland cement (CT) is partially replaced with pozzolans 0-40% by weight of the cementitious materials. Fly ash ground rice husk-bark ash and ground bottom ash have a high potential to be used as a good cementitious material. The results show that the compressive strength and low porosity of self-compacting concrete improves substantially with partial replacement of Portland cement with fly ash. Self-compacting concrete mix cement containing 20-40% of pozzolans can be used to make cementitious materials. The use of fly ash ground rice husk-bark ash and ground bottom ash produces concrete mix with good strength and resistance to chloride and corrosion.
ผลกระทบของระบบความปลอดภัยในงานก่อสร้างที่มีผลต่ออัตราผลผลิต
The purpose of this research is to study the effect of a safety system provided for external wall plastering activity on productivity by studying a construction of commercial buildings. The safety system composed of (1) stable scaffolding system (2) providing clean and not slip walkways on the scaffold (3) installation of handrails not less than 0.90 meters in height along sides of the scaffold (4) installing safety nets around outside perimeters of the scaffolding (5) indicating working area (6) installing stairs (7) providing protection for people who works below (8) providing tools and equipments for transporting material which are safe and ready for using and (9) providing personal protective equipment for workers. Cost of the safety system is 79665 baht for a wall area of 1510 m2 or approximately 53 baht/m2. The prevention cost is quite high because it is an initial investment cost. However contractors could repeat theirs used on future projects. Productivity rates for prior and after the used of safety system are 1.16 and 1.13 m2/person/hr respectively. The productivity declines for approximately 3%. In addition our study found an impact of predecessor activity which is a brick laying activity. If brick walls are not well aligned and plumbed the working time for wall plastering could take longer for 8%. Meanwhile the wall plastering productivity could decrease for 11% and labor cost could increase for 12%.
การทดสอบการอัดตัวของวัสดุผสมภายใต้สภาวะอุณหภูมิต่างๆ
Brake system is used the friction between disk and pads. In the driving conditions the brake behavior from the driver is difference. Based on this reason the damage on disk and pads are occurring. Nowadays the ratio of compound materials in pads is several and involved automotive industry has not available enough to experiment. Thus it is difficult to brake pads damaged analyzing in several driving conditions. In this problem the mechanical property tester is main tool for experimental works and test procedure base on the Brake lining and disc brake pads compressibility JIS D 4413. The experiment emphasizes on the flexibility behavior and internal energy by volume with 3 types of brake lining and pads. For the experiment focused on conditions by normal apply brake repeat apply brake and suddenly apply brake. The results revealed the normal apply brake condition the maximum and minimum of flexibility behavior was appeared on brake lining and pads type A and type C with testing temperature at 200C. By the repeat and suddenly apply brake conditions the brake lining and pads type C and type A with 300C is given to the maximum and minimum flexibility behavior. In case of internal energy by volume the maximum and minimum energy was appeared on pads type C and type B at the 30C of testing temperature. For the testing temperature at 200 and 400C the pads type A and type B were got the maximum and minimum energy respectively. On the other hand at the high flexibility behavior is given to high internal energy at the high temperature of the apply brake condition.
การเปรียบเทียบวัสดุที่ใช้ทำแม่พิมพ์ฉีดที่ทำจากอลูมิเนียมเกรด A7075 กับ เหล็กเกรด P20
Material selection for mold making are not only material prices wages but also there are other factors such as thermal strength shine and resistance to temperature changing that caused distortion and cracks. Preform injection molding from Polyethylene Terephthalate (PET) consumes time for drying granulated plastic in 4 – 6 hours at 140 - 160°C and injects at 280 – 300 °C. This is a very high temperature to inject into mold at 10 – 15°C in cool area. The material for mold making must be able to resist to thermal shock. Today molding machines are made of grade P20 steel (Standard JIS) to produce preform that takes long cycle time due to poor cooling. The research aims to compare the pricing time in mold making to preform injection time that made of aluminum -A7075 grade and grade P20 steel. The experiment is to make a mold that made of aluminum A7075 grade and grade P20 steel injects 15 gram preform. The PET is used to blow into a blow mold with pressure at 30 – 35 bar (Two – Stage) that are 2 bottles of 350 ML. The results of material selection for preform mold making showed that aluminum A7075 grade is cheaper 27.04% the mold price is cheaper 23.6% and consumes less cycle time than grade P20 steel.
การวิจัยปัญหาในงานหล่อและการพัฒนาแนวทางแก้ไขปัญหาในงานหล่อเครื่องประดับสมัยใหม่
Thailand’s gem and jewelry industry is widely considered one of the greatest potential markets in the world. One of the important processes is producing the body jewellery or casting. The lost-wax castingtechnique is a popular technique used widely. However it can also be a source of many defects such as porosity tarnishing incomplete form filling and water stain. There is not finding causes of problems affecting the cost of production labor energy and time increased. This research aims to study the production problems and deficiencies of work piece in the actual work from10 casting industriesto identifying and preventing all these problems. This study will be helpful to entrepreneurs gems and jewelry industry to use as guidelines to prevent defects reduce waste reduce production costs and improve the casting process for the piece even more quality. The study found that most of the production process is the main the machinery / equipment and material problems the problem of secondary respectively by this process the main problem is the casting and foundry molds the injection and the candles prototype and mold making rubber the order is a minor respectively work piece for defects in castings are very common a flaw was found in the specimens I have a 6 specimen defects found in wax and defects found in rubber molds and prototypes the defect occurs in each style be caused by a wide variety of cases. Problems encountered in this study the most hole of the shrinkage problem problem of casting porosity the hole of the bubble the cracking problem the cast is not full the problem is the ceiling.