Studies on dry spinning. I. Fundamental equations

One difficulty in analyzing the state of filament in the dry spinning process is that in the boundary conditions required to solve the equations of mass, momentum and energy which are derived on the consideration of balance with respect to infinitesimally small element are not given a priori. The equations which include these boundary conditions in themselves are derived by considering mass, momentum, and energy balances with respect to the entire cross section of filament. These additional macroscopic equations are simplified to a great extent by assuming the flat velocity profile through the cross section of filament. Besides, in the steady state, these macroscopic equations are modified to give the equations of average solvent content, spinning tension, cross-sectional area, and average temperature. When the spinning conditions are given and the physical constants are measured for a given polymer and solvent system, it becomes possible to calculate the state of filament by solving these microscopic and macroscopic equations simultaneously without resorting to actual spinning.     

Wind energy planning: Development and application of a site selection method for wind energy conversion systems (WECS)

The use of wind energy by means of its conversion to electricity involves a number of constrains such as economic, environmental, technical, legal, social and institutional requirements. Planning for wind energy should solve these issues in the planning process by encouraging opportunities and discouraging constraints associated with the use of wind energy. The opportunities and constraints significant at the regional level (i.e. approximately 10,000 km²) were identified, and a systematic method was developed to select sites for large WECS by incorporating the identified factors. These factors include: wind resource, proximity to load centres, proximity to tie-in points, and exclusive land-use areas. The developed method was applied to the western Massachusetts region, and the first results of the study have been acquired.     

Experimental Facsimile Communication System on Packet Switched Data Network

The use of the public data network for facsimile communication has remarkable advantages with regard to high speed and reliable transmission and, in addition, it is well applicable to provide value added facilities for future service extension. The Research and Development Laboratories of Kokusai Denshin Denwa (KDD) Company, Ltd. have developed an experimental facsimile communication system on the packet switched data network (PSDN). The system is composed of packet switching exchanges (PSE), high speed digital facsimile terminal equipment, a facsimile communication processor (FCP), and facsimile packet assembly/ disassembly equipment (FAX-PAD). The facsimile equipment in the system adopts a two-dimensional modified READ code and has the interface protocol to the PSDN. The FCP provides the store-and-forward facilities to provide such services as delayed delivery, multiaddress delivery, and mailbox service. The FAX-PAD realizes the interworking between facsimile equipments on the public switched telephone network (PSTN) and those on PSDN. After various experiments including international field tests, it was confirmed that the system is useful for future advanced facsimile service.     

A possible activation of cholesterol 7-hydroxylation by S-methylmethionine (vitamin U)

The conversion rate from 14 C-cholesterol to its 7 alpha-hydroxylated metabolites was studied in the microsome system prepared from mice liver with the pretreatment of S-methylmethionine (MMSC). In results, the increased amounts of 7 alpha-hydroxylated metabolites by MMSC show a possible activation of cholesterol 7 alpha-hydroxylase.     

Radiation-induced graft copolymerization of butadiene on polyethylene by trapped radicals

The low-temperature grafting of butadiene on polyethylene (PE) preirradiated in air is compared with that on PE preirradiated in vacuo for the effect of several factors on the grafting. Little fundamental difference between the two cases was observed. In both cases the graft conversion curve is trapped radical type and the overall activation energies are 9.7 and 8.4 kcal/mol for 0.947-density PE and 0.916-density PE, respectively. Percent grafting is proportional to the square root of the dose rate (= total dose). The retarding effect of oxygen at irradiation or storage after irradiation on the grafting scarcely appears when the irradiation temperature or storage temperature is below 15°C. For thinner film and lower density of PE this effect appears clearly at the higher temperature. Therefore, it may be concluded that the low-temperature grafting of butadiene onto PE preirradiated in air is initiated predominantly by nonoxidized radical (allyl radical) trapped in PE and that the grafting reaction occurs in the semicrystalline part of PE.     

HVEM study of crack-tip dislocations in Si crystals prepared by FIB and twin-blade cutting method

Crack-tip dislocations in silicon crystals have been examined by using high-voltage electron microscopy. Cracks were introduced by the Vickers indentation method at room temperature and the indented specimens were annealed at high temperatures to induce dislocations around crack tips under the presence of residual stress due to the indentation. A selected area around a crack tip was thinned by a focused ion beam (FIB) technique. Specimens were thinned in advance by a twin-blade cutting (TBC) method, which is a simple cutting process for saving FIB machine time. A combination of FIB and TBC can be a useful thinning procedure for the efficient preparation of transmission electron microscopy specimens. Characteristic dislocation structures were observed around the tip of a crack, aiding the elucidation of dislocation processes, which is essential to increase the fracture toughness of materials.     

A simulation study on the enhancement of the shift reaction by water injection into a gasifier

Although coal gasification is a clean and efficient use of coal, a reduction of CO₂ emissions is needed to mitigate global warming. The aim of this study was to improve the thermal efficiency of fuel production and electricity generation by dry coal feed gasification. The primary cause of thermal efficiency loss is steam use in a water-gas shift reactor. The shift reactor, installed downstream from the gasifier, uses a catalyst to adjust the H₂/CO ratio of the syngas. We have proposed a new process in which water is injected at the outlet of the gasifier and is vaporized to enhance the extent of the shift reaction. This process utilizes the high temperature of the syngas, which is sufficient for the shift reaction to occur without a catalyst. We have developed a model that incorporates the shift reaction velocity to evaluate our proposed process. In an optimized 5-stage water supply case, we found that the CO conversion reaches 9.9% at a water/syngas ratio of 0.14 mol/mol (water/CO = 0.25 mol/mol); the CO conversion needed for dimethyl ether production is 31%. This new process can improve the efficiency and reduce the cost of coal gasification.     

Ultrashort X-ray pulse generation using subpicosecond electron linac

As a promising tool for ultrafast material analyses, we propose to utilize the X-ray pulse which may be generated in a quite simple manner using subpicosecond electron linacs. The properties of the X-ray were numerically studied with the EGS4 code. Verification of the X-ray generation was also conducted at the Nuclear Engineering Research Laboratory (NERL) linac and clear diffraction patterns of characteristic X-ray were obtained for typical single crystals.