Synthesis of novel photoacid generator containing resist polymer for electron beam lithography

Photoacid generators (PAGs) have been widely used as a key material in the development of novel photoresist materials. One of the important uses of PAGs is found in chemically amplified photoresists (CARs) because of their high photosensitivity and high resolution capability. Triphenylsulfonium salt methacrylate (TPSMA) as the PAG has been bounded in the main polymer backbone. TPSMA was employed for synthesis of terpolymers, poly(MMA-co-tBVPC-co-TPSMA) and poly(tBVPC-co-tBOCPOMI-co-TPSMA) as a positive tone photoresists by free radical polymerization using AIBN. Terpolymers with various ratio of TPSMA, MMA, tBVPC and tBOCOPMI were synthesized and well characterized by FTIR, NMR. Molecular weight distribution was analyzed by GPC. Thermal properties were studied using TGA, DSC which showed thermal stability of terpolymer up to 150 degrees C. We have applied E-beam lithography and KrF lithography in order to demonstrate the effect of the polymer bounded PAG resists. These positive tone resists were successfully applied for fabrication of nano-scale patterns.     

3D neutron tomography of a polymer electrolyte membrane fuel cell under sub-zero conditions

In this article, we implement both 2D and 3D based neutron imaging techniques on a polymer electrolyte membrane (PEFC) fuel cell under sub-zero conditions. A cell was run at steady state power, purged for 60 s, and then brought down to −5 °C inside an environmental chamber situated in front of a neutron beam. A series of 2D radiographs were taken as the cell dropped in temperature capturing the condensation and redistribution of flow field and gas diffusion layer (GDL) water. Immediately after this, 3D tomography was conducted while the cell remained at −5 °C. The image data was reconstructed into a 3D model in order to highlight regions where water/ice formations occur. The tomography results show where ice forms within the flow field and which regions are subject to blockages. Ice is observed predominately under channel areas due to water rejection by the GDL. The cathode side channel exit region displays higher ice content which correlates with elevated saturation levels from reaction water production during operation. Larger ice formations reside in the lower region of the flow field due to gravity. These blockages may pose significant issues to cold start of the cell as well as highlight potential drawbacks to shorter purge durations.     

The computer-aided analysis for the driving stability of a plug-in fuel cell vehicle using a proton exchange membrane fuel cell

In order to analyze the driving stability of a plug-in fuel cell vehicle (PFCV), a computer-aided simulator for PFCVs has been developed. PFCVs have been introduced around the world to achieve early commercialization of an eco-friendly and highly efficient fuel cell vehicle. The plug-in option, which allows the battery to be recharged from the electricity grid, enables a reduction in size of the fuel cell system (FCS) and an improvement of its durability. As such, the existing limitations of the fuel cell - such as its high cost, poor durability, and the insufficient hydrogen infrastructure – can be overcome. During the design phase of PFCV development, simulation-based driving stability test is necessary to determine the sizes of the electric engine of the FCS and the battery. The developed simulator is very useful for analyzing the driving stability of the PFCV with respect to the capacities of the FCS and battery. The simulation results are in fact very close to those obtained from a real system, since the estimation accuracy of PFCV component models used in this simulator, such as the fuel cell stack, battery, electric vehicle, and the other balance of plants (BOPs), are verified by the experiments, and the simulator uses the newly-proposed power distribution control logic and the pre-confirmed real driving schedule. Using these results, we can study which one will be the best in terms of driving stability.     

Comparative ultrastructure of the fertilized egg envelope in Corydoras adolfoi and Corydoras sterbai,Callichthyidae, Teleostei

In teleost, the structural characteristics of fertilized egg and egg envelope are very important for classification of genus or species. The structures of fertilized egg and egg envelope from Corydoras adolfoi and Corydoras sterbai, Callichthyidae, Siluriformes in teleost were examined by scanning and transmission electron microscopes to confirm whether these morphological structures have specificities of species and family or not. The fertilized eggs of C. adolfoi and C. sterbai were non‐transparent, spherical, demersal, and strong adhesive. There were no structural differences between two species through the light microscope. The size of the fertilized eggs of C. adolfoi was 1.95 ± 0.03 mm (n = 20), and that of C. sterbai was 1.92 ± 0.03 mm (n = 20). The perivitelline space was almost not developed in both species. In both species, the adhesive protuberances structures were on the outer surface of egg envelope. And fibrous structures were specially located at attachment part of spawning bed. And the egg envelope consisted of two layers, an inner lamellae layer and an outer strong adhesive layer with high electron dense protuberances structures in cross section. Consequentially, the fertilized eggs, outer surface on the egg envelope and cross section of egg envelope have identical structure. So, these structural characteristics of fertilized eggs and egg envelope show genus Corydoras specificity.     

Matching of physical experiments and multibody dynamic simulation for large deformation problems

Many papers have studied computer simulations of elastic bodies undergoing large deflections and large deformations. But there have not been many attempts to check the validity of the numerical formulations because the simulation results could not be matched without correct input data such as material properties and damping effects. In this paper, these values are obtained from real experiment with a high-speed camera and a data acquisition system. The simulation results with the absolute nodal coordinate formulation (ANCF) are compared with the results of real experiments. Two examples, a thin cantilever beam and a thin plate, are studied to verify whether the simulation results are well matched to experimental results.     

Pilot ability to anticipate the consequences of flight actions as a function of expertise

The study offers insights into pilot ability to anticipate consequences of actions and how this ability changes with experience. Novice and expert pilots completed trials in which 3 screens depicted a control movement (or control movements), a cockpit flight situation, or a change in flight situation. Changes depicted in the 3rd screen of each trial were consistent, inconsistent with the mental model of the effect of the control movement or movements, or inconsistent with the application of the control movement(s) to the current flight situation. Pilots indicated whether the depicted change was inconsistent or consistent with their expectations, and accuracy of consistency judgments was greater for mental-model than for situation-model inconsistent statements. Experts are more accurate than novices, particularly for trials that involve multiple, meaningfully related control movements. Expert ability to organize information into meaningful units appears to facilitate future flight state projections, and projection failures appear to result from situation- rather than mental-model failures. Actual or potential applications of this research include analysis of flight situation awareness and flight performance errors.     

A 155-mW 50-m vertices/s graphics processor with fixed-point programmable vertex shader for mobile applications

A 36 mm/sup 2/ graphics processor with fixed-point programmable vertex shader is designed and implemented for portable two-dimensional (2-D) and three-dimensional (3-D) graphics applications. The graphics processor contains an ARM-10 compatible 32-bit RISC processor,a 128-bit programmable fixed-point single-instruction-multiple-data (SIMD)vertex shader, a low-power rendering engine, and a programmable frequency synthesizer (PFS). Different from conventional graphics hardware, the proposed graphics processor implements ARM-10 co-processor architecture with dual operations so that user-programmable vertex shading is possible for advanced graphics algorithms and various streaming multimedia processing in mobile applications. The circuits and architecture of the graphics processor are optimized for fixed-point operations and achieve the low power consumption with help of instruction-level power management of the vertex shader and pixel-level clock gating of the rendering engine. The PFS with a fully balanced voltage-controlled oscillator (VCO) controls the clock frequency from 8 MHz to 271 MHz continuously and adaptively for low-power modes by software. The chip shows 50 Mvertices/s and 200 Mtexels/s peak graphics performance, dissipating 155 mW in 0.18-/spl mu/m 6-metal standard CMOS logic process.     

Measurement of the specific heat of Zr–40 wt%U metallic fuel

The specific heat capacities of un-irradiated and irradiated metallic Zr–40 wt%U fuel have been measured between 50 °C and 1000 °C with a differential scanning calorimetry. The irradiated fuels have three different burnup levels of 0.38, 0.70 and 0.92 g-fission product (FP)/cm³. The measured specific heat for the un-irradiated fuel is representative and consistent with the values estimated from the Neumann–Kopp rule. The irradiated fuels exhibited a complicated behavior of the heat capacities. The unique characteristics of the specific heat capacities can be explained by the recovery of radiation damage, the formation of fission gas bubbles and fission gas release, and a phase transition in the irradiated fuels. An examination of the microstructure revealed that multiple large bubbles were formed in the irradiated fuel during specific heat measurement. The measured specific heat is expected to enable us to estimate the stored energy in the metallic fuel during certain accident scenarios and to determine the thermal conductivity of zirconium–uranium metallic fuel.     

The reduction of iron oxides by volatiles in a rotary hearth furnace process: Part II. The reduction of iron oxide/carbon composites

The reduction of iron oxide/carbon composite pellets with hydrogen at 900 °C to 1000 °C was studied. Compared to hydrogen, the reduction by carbon was negligible at 900 °C and below. However, significant carbon oxidation of the iron oxide/graphite pellets by H₂O generated from the reduction of Fe₂O₃ by H₂ was observed. At higher temperatures, reduction by carbon complicates the overall reduction mechanism, with the iron oxide/graphite composite pellet found to be more reactive than the iron oxide/char composite pellet. From the scanning electron micrographs, partially reduced composite pellets showed a typical topochemical interface with an intermediate region between an oxygen-rich unreacted core and an iron-rich outer shell. To determine the possibility of reduction by volatiles, a layer of iron oxide powders was spread on top of a high volatile containing bituminous coal and heated inside a reactor using infra-red radiation. By separating the individual reactions involved for an iron oxide/coal mixture where a complex set of reactions occur simultaneously, it was possible to determine the sole effect of volatile reduction. It was found that the light reducing gases evolve initially and react with the iron oxide, with complex hydrocarbons evolving at the later stages. The volatiles caused about 20 to 50 pct reduction of the iron oxide.