38—A FINITE-DEFORMATION THEORY OF THE 2/2-TWILL WEAVE UNDER BIAXIAL EXTENSION

A mechanical model of the 2/2-twill weave is presented in order to investigate the tensile properties of this weave under biaxial extension. The theory predicts that the compressional deformations of the warp and the weft at their cross-over point produce a superior effect on the tensile properties of the weave, especially in the relatively small-extension state. Experimental investigation to examine the accuracy of this theory is also reported, and good agreement between the theory and the experimental result is demonstrated.     

Voltage holding study of 1 MeV accelerator for ITER neutral beam injector

Voltage holding test on MeV accelerator indicated that sustainable voltage was a half of that of ideal quasi-Rogowski electrode. It was suggested that the emission of the clumps is enhanced by a local electric field concentration, which leads to discharge initiation at lower voltage. To reduce the electric field concentration in the MeV accelerator, gaps between the grid supports were expanded and curvature radii at the support corners were increased. After the modifications, the accelerator succeeded in sustaining -1 MV in vacuum without beam acceleration. However, the beam energy was still limited at a level of 900 keV with a beam current density of 150 A∕m(2) (346 mA) where the 3 × 5 apertures were used. Measurement of the beam profile revealed that deflection of the H(-) ions was large and a part of the H(-) ions was intercepted at the acceleration grid. This causes high heat load on the grids and the breakdowns during beam acceleration. To suppress the direct interception, new grid system was designed with proper aperture displacement based on a 3D beam trajectory analysis. As the result, the beam deflection was compensated and the voltage holding during the beam acceleration was improved. Beam parameter of the MeV accelerator was increased to 980 keV, 185 A∕m(2) (427 mA), which is close to the requirement of ITER accelerator (1 MeV, 200 A∕m(2)).     

Heat transfer enhancement by Marangoni convection in the NH3–H2O absorption process

The objectives of this paper are to quantify the effect of Marangini convection on the absorption performance for the ammonia–water absorption process, and to visualize Marangoni convection that is induced by adding a heat transfer additive, n-octanol. A real-time single-wavelength holographic interferometer is used for the visualization using a He–Ne gas laser. The interface temperature is always the highest due to the absorption heat release near the interface. It was found that the thermal boundary layer (TBL) increased faster than the diffusion boundary layer (DBL), and the DBL thickness increased by adding the heat transfer additive. At 5 s after absorption started, the DBL thickness for 5 mass% NH₃ without and with the heat transfer additive was 3.0 and 4.5 mm, respectively. Marangoni convection was observed near the interface only in the cases with heat transfer additive. The Marangoni convection was very strong just after the absorption started and it weakened as time elapsed. It was concluded that the absorption performance could be improved by increasing the absorption driving potential (x_vb−x_vi) and by increasing the heat transfer additive concentration. The absorption heat transfer was enhanced as high as 3.0–4.6 times by adding the heat transfer additive that generated Marangoni convection.     

Performance analysis of air cycle refrigerator integrated desiccant system for cooling and dehumidifying warehouse

In this paper, the performance of air cycle refrigerator integrated desiccant system used to cool and dehumidify warehouse is analyzed theoretically. Simulation analysis is carried out to calculate the system coefficient of performance, cooling effects and the humidity change under different values of pressure ratio, storage zone temperature inside dock and outdoor air conditions. Also, the effect of the air cycle and the rotor parameters on the system performance is evaluated. From the simulation result it is found that, the desiccant system has the ability to supply air to the dock area at very low humidity. The system coefficient of performance increases due to the exhaust heat recovery on the desiccant system, and this enhancement can be more than 100%. The coefficient of performance of the proposed system is greater than that of a conventional system under the same operating conditions.     

Review of advanced absorption cycles: performance improvement and temperature lift enhancement

The objective of this study is to propose and evaluate advanced absorption cycles for the coefficient of performance (COP) improvement and temperature lift enhancement applications. The characteristics of each cycle are assessed from the viewpoints of the ideal cycle COP and its applications. The advanced cycles for the COP improvement are categorized according to their heat recovery method: condensation heat recovery, absorption heat recovery, and condensation/absorption heat recovery. In H₂O–LiBr systems, the number of effects and the number of stages can be improved by adding a third or a fourth component to the solution pairs. The performance of NH₃–H₂O systems can be improved by internal heat recovery due to their thermal characteristics such as temperature gliding. NH₃–H₂O cycles can be combined with adsorption cycles and power generation cycles for waste heat utilization, performance improvement, panel heating and low temperature applications. The H₂O–LiBr cycle is better from the high COP viewpoints for the evaporation temperature over 0°C while the NH₃–H₂O cycle is better from the viewpoint of low temperature applications. This study suggests that the cycle performance would be significantly improved by combining the advanced H₂O–LiBr and NH₃–H₂O cycles.     

Mass recovery adsorption refrigeration cycle—improving cooling capacity

The study investigates the performance of two-bed, silica gel-water adsorption refrigeration cycle with mass recovery process. The cycle with mass recovery can be driven by the relatively low temperature heat source. In an adsorption refrigeration cycle, the pressures in adsorber and desorber are different. The chiller with mass recovery process utilizes the pressure difference to enhance the refrigerant mass circulation. Cooling capacity and coefficient of performance (COP) were calculated by cycle simulation computer program to analyze the influences of operating conditions. The mass recovery cycle was compared with conventional cycle such as the single stage adsorption cycle in terms of cooling capacity and COP. The results show that the cooling capacity of mass recovery cycle is superior to that of conventional cycle and the mass recovery process is more effective for low regenerating temperature.     

Graphite formation on Ni film by chemical vapor deposition

Thin film formation of graphite by chemical vapor deposition using 2-methyl-1,2′-naphthyl ketone as a starting material was carried out on Ni film substrates. On Ni films directly deposited on quartz glass, the graphite films were obtained when the Ni film thickness was above 1 000 Å and above 5 000 Å at 700 °C and 1 000 °C, respectively. Depositions on thinner Ni film substrates comprise amorphous carbon (a-C) or graphite tubes which was owing to the thermal coagulation of the Ni film into droplets. On the other hand, graphite film was obtained on the Ni film with thickness 10 Å when a-C was inserted between the Ni film and the quartz glass. The coagulation of the Ni film is considered to be avoided by inserting a-C layer.     

Wave drift force in a two-layer fluid of finite depth

Based on the momentum and energy conservation principles, a compact calculation formula is analytically derived for the wave-drift force on a 2-D body floating in a two-layer fluid of finite depth. In a two-layer fluid, two different wave modes (the surface-wave mode with longer wavelength and the internal-wave mode with shorter wavelength) exist not only in the incident wave but also in the body-scattered wave, and these wave characteristics are properly incorporated in the obtained formula. It is noted that, unlike the single-layer case, the wave-drift force can be negative in the incident wave of surface-wave mode, if the transmitted wave with internal-wave mode is large. Numerical computations are implemented for a Lewis-form body by means of the boundary-integral-equation method with Green’s function for the two-layer fluid problem. The effects of density ratio, interface position, and body motions on the wave-drift force are studied, and some important features are found for two-layer fluids.     

Soluble functionalized carbon nanohorns

Carbon nanahorns (CNH) were functionalized following the methodology of 1,3-dipolar cycloaddition of azomethine ylides and found to form stable solutions in either organic solvents or water. The number of added functional units, in the form of pyrrolidine moieties, was calculated when a pyrene chromophore was utilized in the modification scheme. Moreover, complementary theoretical calculations revealed that reactivity enhancement is expected at locations near the conical-shaped tip of CNH, where the highest curvature and strain exist. Finally, additional organic transformation of already modified CNH was exploited by covalently linked ferrocene units.     

p53 and K-ras status in duodenal adenomas in familial adenomatous polyposis

BACKGROUND: The genetic alterations in patients with familial adenomatous polyposis (FAP) and duodenal adenomas are poorly characterized when compared with data relating to colorectal tumorigenesis in the same patients. METHODS: Point mutation of the K-ras oncogene and point mutation and overexpression of the TP53 tumour suppressor gene were investigated in 32 duodenal polyps (seven without mucosal pathology, 23 with mildly dysplastic adenomas and two with moderately dysplastic adenomas) from 21 patients with FAP. RESULTS: K-ras mutation, TP53 mutation or positive p53 staining were not found in duodenal polyps without histological abnormality. Of 25 duodenal adenomas, K-ras mutation was found in three (two mildly dysplastic, one moderately dysplastic), 20 showed positive p53 immunostaining, and mutation of the TP53 gene was found in one moderately dysplastic adenoma. p53 protein overexpression in duodenal adenomas was significantly more frequent than mutation of either K-ras or TP53 (P < 0.01). CONCLUSION: p53 dysfunction is a hallmark of duodenal adenomas in patients with FAP. Overexpression may indicate DNA damage and thus an early step in tumorigenesis.