A method for calculating the electromagnetic noise of a motor-driven thin blade fan

An urgent need exists to develop a method of predicting the noise level of a blade fan attached to a motor shaft. To satisfy this requirement, we developed a method for calculating the sound generated when a rotating blade is excited by the torque pulsation of a motor. The sound pressure values calculated by the new method for a rotating blade were found to correspond well with experimentally measured ones.     

High temperature electrochemical heat pump using water gas shift reaction. Part I: Theoretical considerations

A new electrochemical heat pump using a combination of an electrolytic reaction at lower temperature to absorb low grade thermal energy and a thermochemical reaction at higher temperature to produce more efficient thermal energy is proposed. At a lower temperature, an endothermic reaction which cannot occur thermochemically proceeds with electrolysis. At a higher temperature, an exothermic reaction which is the reverse of the electrolysis reaction occurs thermochemically to produce high grade thermal energy. The water gas shift reaction, CO₂(g) + H₂(g) CO(g) + H₂O(g), in molten carbonate is one possible candidate for the new electrochemical heat pump and can lead to an increase in the temperature of the thermal energy from 1100 to 1200K. A heat pump system using the shift reaction is also considered theoretically.     

Effect of outliers on forecasting temporally aggregated flow variables

Economic time series are of two types: stock and flows, and may be available at different levels of aggregation (for instance, monthly or quarterly). The economist, in many situations, is interested in forecasting the aggregated observations. The forecast function, in this case, can be based either on the disaggregated series or the aggregated series. The forecasts based on the disaggregated data are at least as efficient, in terms of mean squared forecast errors, as the forecasts based on temporally aggregated observations when the data generating process (DGP) is a known ARIMA process. However, the effect of outliers on both forecast functions is not known. In this paper, we consider the effect of additive and innovation outliers on forecasting aggregated values based on aggregated and disaggregated models when the DGP is a known ARIMA process and the presence of the outliers is ignored. Results when the model is not known and tests applied for the detection of outliers are derived through simulation.     

High-strength small reinforcement for spliced optical fibre

A high-strength small reinforcement using a nylon and a steel wire has been developed. The size of the reinforcement is 1 mm in diameter and 35 mm in length. An average tensile strength of 5.4 kg has been achieved with negligible loss increase.     

Effect of the size of nuclei on crystallization behavior of Li2O · 2SiO2 glass

Crystallization peak temperature was measured for Li₂O · 2SiO₂ glass with various number densities of nuclei induced by long heat-treatment (405 h) at 460°C. Its crystallization process of Li₂O · 2SiO₂ glass was simulated numerically in order to examine the effect of the initial size of nuclei on crystallization behavior, and the relationship between crystallization peak temperature and the number density of nuclei in the glass was considered. It was found that the effect of nuclei size is not significant when the heat-treatment temperature is lower than 460°C. By considering the effect of nuclei size, number density of nuclus was evaluated by DTA method accurately.     

Imaging of the expansion of femtosecond-laser-produced silicon plasma atoms by off-resonant planar laser-induced fluorescence

Planar laser-induced fluorescence measurements were used to investigate the expansion dynamics of a femtosecond laser-induced plasma. Temporally and spatially resolved measurements were performed to monitor the atoms that were ablated from a silicon target. A dye laser (lambda = 288.16 nm) was used to excite fluorescence signals. The radiation of an off-resonant transition (Si 390.55 nm) was observed at different distances from the target surface. This allowed easy detection of the ablated Si atoms without problems caused by scattered laser light. Abel inversion was applied to obtain the radial distribution of the Si atoms. The atom distribution in the plasma shows some peculiarities, depending on the crater depth.     

Formation and crystallization of gels in the Na2O-SiO2-TiO2-ZrO2 system

5Na₂O·95(SiO₂ + TiO₂ + ZrO₂) gels together with Na₂O-MO₂ gels (MO₂ = SiO₂, TiO₂, ZrO₂) were synthesized and effect of Na₂O addition to the gel formation and crystallization behavior were studied. From Si(OC₂H₅)₄, Ti(iso-OC₃H₇)₄, Zr(n-OC₃H₇)₄ and NaOCH₃ solutions in EtOH without H₂O, transparent, opaque and heterogeneous gels were obtained. By SEM observation, it was found that the opague bulk gels, rich in TiO₂ or ZrO₂ component, contain agglomerated spherical particles of less than 10 m diameter. Crystallization temperature (Tc) measured by DTA decreased sharply from 1258°C (SiO₂) to 613°C (30Na₂O·70SiO₂) due to the increasing non-bridging oxygens in the Na₂O-SiO₂ system. But in the Na₂O-TiO₂ and Na₂O-ZrO₂ systems, Tc increased as Na₂O content was increased up to 10 mol%. The thermal stability, defined by Tc/TL ratio, decreased from Tc/TL = 0.77 (SiO₂) to 0.57 (5Na₂O·95SiO₂) or increased from Tc/TL = 0.30 (TiO₂) to 0.67 (30Na₂O·70TiO₂) with Na₂O addition. In the 5Na₂O·95(SiO₂ + TiO₂ + ZrO₂) system maximum Tc was 891°C at 5Na₂O·76SiO₂·19ZrO₂ composition and decreased as TiO₂ or ZrO₂ contents increased. Compared with the SiO₂-TiO₂-ZrO₂ gels, Tc of the 5 mol%Na₂O containing gels (Na₂O-SiO₂-TiO₂-ZrO₂) was lower in SiO₂ rich composition and higher in TiO₂ or ZrO₂ rich compositions. It is assumed that addition of Na₂O changed the structure of amorphous TiO₂ and ZrO₂ someway to increase their thermal stability or amorphous forming ability. After DTA run up to 1000°C, cystalline phases precipitated in the 5Na₂O·95(SiO₂ + TiO₂ + ZrO₂) gels were determined by XRD analysis.     

Selection of manipulator system for multiple-goal task by evaluating task completion time and cost with computational time constraints

The focus of this study is on the problem of manipulator system selection for a multiple-goal task by evaluating task completion time and cost with computational time constraints. An approach integrating system selection, structural configuration design, layout design, motion planning, and relative cost calculation is proposed to solve this problem within a reasonable computational time. In the proposed approach, multiple-objective particle swarm optimization (MOPSO) is utilized to search for the appropriate manipulator system with appropriate structural configuration from a set of candidate systems. Particle swarm optimization (PSO) and the nearest neighborhood algorithm are employed in layout design and motion planning due to their high convergence speed. Three methods involving a random search algorithm are compared to the proposed approach through a simulation. The simulation is done with a set of tasks and the result shows the effectiveness of the proposed approach.