Rapid Tooling by Powder Casting Transferred from RIP Model -Manufacturing Conditions Pursuing Zero Shrinkage

High accuracy is being sought in the rapid manufacturing of long life metal dies and molds by transferring from layer laminated models. Powder casting serves as a promising rapid tooling method as it enables high density filling and thus controls dimensional shrinkage to a considerable extent during sintering and infutrating This study aims to study the relation between the tooling conditions and dimensional changes of powder casting and fmd the conditions at which dimensional changes are minimum. In the experiments performed, a golf ball model was chosen as an exampIe of a small mold and results show that dimensional changes can be controlled to below 0.1%, which will facilitate practical application. By subjecting the cast powder to vibrations after adding the binder to achieve higher density, and adding fme copper powder to a mixture of two different size stainless steel powders for dimensional adjustments, almost zero shrinkage control in rapid tool making was realized.Mechanical Engineerin

Comparison in bone turnover markers during early healing of femoral neck fracture and trochanteric fracture in elderly patients

Healing of fractures is different for each bone and bone turnover markers may reflect the fracture healing process. The purpose of this study was to determine the characteristic changes in bone turnover markers during the fracture healing process. The subjects were consecutive patients with femoral neck or trochanteric fracture who underwent surgery and achieved bone union. There were a total of 39 patients, including 33 women and 6 men. There were 18 patients (16 women and 2 men) with femoral neck fracture and 21 patients (17 women and 4 men) with trochanteric fracture. Serum bone-specific alkaline phosphatase (BAP) was measured as a bone formation marker. Urine and serum levels of N-terminal telopeptide of type I collagen (NTX), as well as urine levels of C-terminal telopeptide of type I collagen (CTX) and deoxypyridinoline (DPD), were measured as markers of bone resorption. All bone turnover markers showed similar changes in patients with either type of fracture, but significantly higher levels of both bone formation and resorption markers were observed in trochanteric fracture patients than in neck fracture patients. BAP showed similar levels at one week after surgery and then increased. Bone resorption markers were increased after surgery in patients with either fracture. The markers reached their peak values at three weeks (BAP and urinary NTX), five weeks (serum NTX and DPD), and 2–3 weeks (CTX) after surgery. The increase in bone turnover markers after hip fracture surgery and the subsequent decrease may reflect increased bone formation and remodeling during the healing process. Both fractures had a similar bone turnover marker profile, but the extent of the changes differed between femoral neck and trochanteric fractures

Miniature Water Ion Thruster; 1 km/s-class Delta-V for a 6U CubeSat

A propulsion system gives CubeSats the capacity to change their orbit on their own, and in terms of achieving a large delta-V, electric propulsion has an advantage. Installing the electric propulsion on CubeSats has difficulties such as a high-pressure gas system, electrical components, and the drop of the efficiency because of the miniaturization. To clear these problems, the water ion thruster is proposed as a candidate for the CubeSats’ electric propulsion. Water has an absolute advantage of applying for CubeSats’ propulsion system in the point of safety. In addition, water is a liquid phase at room temperature and atmospheric pressure, and it makes easy to store and handle it. The thrust measurement and the improvement of the thruster based on experiments were conducted. The thrust and the specific impulse were estimated as 226 ± 19 μN and 384 ± 33 s at the highest performance point with 36.5 W power consumption of all system. It achieved a delta-V of 504 ± 43 m/s with the 1 kg of propellant for an 8 kg and 6U CubeSat

Multiple Water Propulsion Systems: All Propulsive Capabilities for CubeSats From LEO to Deep Space

The proposal is a multiple water propulsion system which combines a water resistojet and water ion thruster

Pre-Flight Testing Results of Multiple Water Propulsion Systems - Resistojet and Ion Thruster for SmallSats

This paper described re-flight flight testing results of the miniature water propulsion system combined an ion thruster and resistojet thrusters which is to be demonstrated on-orbit by JAXA’s program named Innovative Satellite Technology Demonstration-3. The unified propulsion system has a huge potential to expand micro/nano-spacecraft utilization and decrease the risk of debris