Vacuum seal for a rectangular flange

A new vacuum seal for a rectangular flange used in r.f. equipments, was developed. The vacuum seal consists of a recess with a flat surface, machined into a rectangular flange, a rectangular metal gasket with a raised projection on one face, and a mating flange with a recess and raised projection. No leak greater than 1 × 10⁻¹⁰ Pa m³/s was found in leak tests, before and after baking cycles (100 °C, 12 h).     

PROPOSAL FOR A NOVEL CHEMICAL HEAT PUMP DRYER

A new chemical heat pump (CHP) system for ecofriendly effective utilization of thermal energy in drying is proposed from the viewpoints of energy saving and environmental impact. CHPs can store thermal energy in the form of chemical energy by an endothermic reaction and release it at various temperature levels for heat demands by exo/endothermic reactions. CHPs have potential for heat recovery and dehumidification in the drying process by heat storage and high/law temperature heat release. In this study, we estimate the potential of the CHP application to drying systems for industrial use. Some combined systems of CHPs and dryers are proposed as chemical heat pump dryers (CHPD). The potential for commercialization of CHPDs is discussed.     

Cavity-length-dependent spectral and temporal characteristics ofthe gain switched V-groove quantum-wire laser

The cavity-length-dependent spectral and temporal characteristics of a V-groove AlGaAs-GaAs quantum-wire (QWR) laser are investigated. At short cavity lasers less than 300-μm, a discrete wavelength switching from the first (n=1; 837.7 nm for the 800-μm cavity) to the second (n=2;826.5 nm for the 220-μm cavity) subbands occurs due to the increased threshold gain, resulting from the increased cavity loss. Utilizing this characteristic, ultrafast lasing behaviors at the n=1 and n=2 quantized transitions of the QWR, generated by the gain-switching method, are demonstrated and compared     

Remarkable enhancement in durability of Pd/H-ZSM-5 zeolite catalysts for CH4-SCR

Effect of second components on the catalytic performance of Pd/H-ZSM-5 zeolite (Pd: 0.4 wt.%) was evaluated by a durability test of NO reduction with CH₄ at a relatively high temperature of 500°C in the presence of water vapor for a prolonged period. The Pd/H-ZSM-5 showed high stable activity for this reaction without H₂O in the reactant feed, while immediate and irreversible deactivation was observed in the presence of H₂O, resulting in no activity after 7 h. The second components such as Co, Rh, Ag, Ce, and Fe introduced individually to the Pd/H-ZSM-5 enhanced the durability, and in particular the addition of 3.3 wt.% Co led to a stable NO conversion for more than 40 h in the presence of H₂O.     

A multilevel PWM strategy suitable for high‐voltage motor direct drive systems with consideration of the adverse effect of dead time

Recently, high‐voltage motor direct drive systems have been put to practical use, and various multilevel PWM strategies have also been proposed. This paper describes a multilevel PWM strategy [our group calls it the Carrier Phase Selection Method (CPS)] that has the lowest line voltage harmonic distortion in order to prevent the degradation of high‐voltage motor winding insulations. This method takes the adverse effect of dead time into consideration, and it controls the shift direction of a carrier phase. Therefore, a favorable output waveform without instantaneous voltage surges is achieved even if the line voltage level changes. Moreover, the switching transitions across all switching devices are well‐balanced, so the utilization of inverter unit cells is equalized. This is an important factor when designing the entire system. Based on simulation and experimental results, it is shown that this CPS method is particularly effective in high‐voltage motor direct drive systems. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(2): 77–88, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20474     

A 20 kbit associative memory LSI for artificial intelligencemachines

A 20 kb (512 words×40 b) CMOS associative-memory LSI is described. This LSI performs large-scale parallelism for highly efficient associative operations in artificial intelligence machines. Relational search, large-bit-length data treatment, and quick garbage collection are realized on the single-chip associative-memory LSI. A cell array structure has been designed in order to reduce the chip area. A newly designed simple accelerator circuit allows for high-speed search operations. The LSI is fabricated using 1.2 μm double-aluminium-layer CMOS process technology. 284000 devices have been integrated on a 5.3×7.9 mm² chip. The measured minimum cycle time and power dissipation at 10 MHz operation are 85 ns and 250 mW, respectively. The associative memory, with its highly efficient associative operation capabilities, promises to be a large step toward the development of high-performance artificial intelligence machines     

Combining linguistic resources to create a machine-tractable Japanese-Malay dictionary

We present a method for combining two bilingual dictionaries to make a third, using one language as a pivot. In this case we combine a Japanese-English dictionary with a Malay-English dictionary, to produce a Japanese-Malay dictionary. Our method differs from previous methods in its improved matching through normalization of the pivot language. We have made a prototype dictionary of around 76,000 Japanese-Malay pairs for 50,000 Japanese head words.     

Selective conversion of CO into methanol at ordinary temperature, part 5. Using an electrochemical photocell

Carbon monoxide has been selectively converted to methanol by means of an electrochemical photocell composed of the n-CdS photoanode and the Everitt's salt-modified platinum cathode. The catholyte was the CO-saturated aqueous solution containing a metal complex and a primary alcohol operating as homogeneous catalysts. In the anolyte, various reducing agents were added to reduce the holes created at the semiconductor. The current efficiency of the methanol formation was almost 100%, irrespective of the kind of metal complex if the reducing agent added as a hole scavenger to the anolyte has a sufficiently negative redox potential.     

Evaluation of Stress and Crystal Quality in Si During Shallow Trench Isolation by UV-Raman Spectroscopy

Defects and stress gradually accumulate throughout various Si large-scale integration fabrication processes. It is essential to monitor defects and stress carefully to suppress their unintentional introduction. In this study, we measured the stress and crystal quality in shallow trench isolation (STI) samples by ultraviolet (UV)-Raman spectroscopy with an extremely high-resolution wavenumber to evaluate the effect of post-annealing on the recovery of Si crystals. The variations of crystal quality in 200-mm wafers with STI structures gradually decreased after post-annealing for 4 h, 6 h, and 8 h; however, there was no substantial difference in the values of full-width at half-maximum of the Raman spectra. Precise measurements of variations of stress and crystal quality were successfully performed by UV-Raman spectroscopy with a high-resolution wavenumber, which enabled us to evaluate the STI process accurately.