Bandwidth and region division for broadband multi-cell networks

A cell planning technique termed BRD (bandwidth and region division) is presented for overcoming interference, maintaining QoS (quality of service) and improving channel capacity over OFDM (orthogonal frequency division multiplexing)-based broadband cellular networks. Through an optimal combination of sectorization and zero padding, bandwidth and region division is achieved that minimizes the outage probability for forward-link cell planning. In order to verify the effectiveness of the proposed algorithm, a Monte Carlo simulation is performed over multi-cell environments.     

Mesomorphic polyblends of poly(p-phenylene terephthalamide) and poly(4,4′-terephthanilide adipamide)

A simultaneous dissolution of two lyotropic polyamides, poly(p-phenylene terephthalamide) (PPTA) and poly(4,4′-terephthanilidc adipamide) (PTAd), in a concentrated H₂SO₄ (1 to 1.5% wt) produced an isotropic single phase solution. The crystallinity of PPTA/PTAd blends confirmed formation of a mesomorphic polyblend to the molecular level. With increasing concentration, solutions of these PPTA/PTAd blends in 100% H₂SO₄ showed a sequential phase change typical of a single lyotropic polymer. Further, the ternary solution exhibited a wider biphase range than both binary solutions of PPTA/100% H₂SO₄ and PTAd/100% H₂SO₄. Dry-jet wet spinning of anisetropic solution of this ternary composition with a PTAd weight fraction less than 0.5 enabled us to obtain PPTA/PTAd blend fibers. Including a PTAd weight fraction of 0.1-0.15 reduced both the orientation angle and fibrillation. The particular blend fiber with a PTAd weight fraction of 0.15 exhibited a synergistic effect on the mechanical properties.     

The relationship between disinfection by-products formation and characteristics of natural organic matter in raw water

The influence of the characteristics of natural organic matter (NOM) on disinfection by-product formation was investigated for Maeri raw water, located in downstream of Nakdong river and Hoedong reservoir at Busan in Korea. The NOM was chlorinated and analyzed for trihalomethanes (THMs), 5 haloacetic acids (HAA-5) and total organic halide (TOX). Aromatic contents determined by specific UV absorbance at 254 nm (SUVA) correlated well with THMs, HAA-5 and TOX formation for the NOM in the Maeri raw water and Hoedong reservoir. Especially, THMFP/DOC showed better correlation with SUVA than HAAFP-5/DOC and TOXFP/DOC with SUVA. Chloroform formation showed good correlation with SUVA for Maeri raw water, but poor correlation with SUVA for the Hoedong raw water. In addition, TCAA formation potential showed good correlation with SUVA for both raw waters. In contrast, a lack of correlation was observed for DCAA formation for both raw waters. THM formation per unit DOC concentration was 70.2–81.1% and 18.9–29.8% for hydrophobic and hydrophilic organic matter in the Maeri raw water, respectively, in which the hydrophobic organic matter had much higher THM formation. In contrast, HAA-5 formation per unit DOC concentration varied seasonally for Maeri raw water. THM formation in the Maeri raw water had a good correlations with SUVA regardless of the ratio of hydrophobic and hydrophilic fraction, and THM formation per unit DOC concentration was higher for the order of humic acid>fulvic acid>hydrophilic organic matter. HAA-5 formation per unit DOC concentration for the hydrophilic organic matter was about 30 μg per mg DOC regardless of SUVA values, but HAA-5 formation per unit DOC concentration for the hydrophobic organic matter was proportionally increased with increasing SUVA values. However, the HAA-5 formation per mg DOC was the highest for the hydrophilic organic matter.     

Incorporation of urea for transplanted rice as affected by floodwater and growing season

Incorporation of urea into puddled rice soils is known to reduce ammoniacal-N buildup in floodwater and the subsequent loss of N as ammonia. Little is known, however, about seasonal and temperature effects on the effectiveness of basal urea incorporation in puddled soils. A field experiment was conducted in northern Vietnam on an Aquic Ustifluvent in the spring season (February to June) and summer season (July to November) to determine the effect of the presence of floodwater and method of fertilizer incorporation on floodwater ammoniacal-N, floodwater urea-N, andpNH₃ following urea application. During the 4 d following basal urea application, floodwater temperature at 1400 h was 7 to 15°C higher in summer (July) than that in spring (February), and floodwater pH at 1400 h was 0.5 to 1.0 higher in summer than that in spring. ThepNH₃ was much higher in summer than that in spring, suggesting a high potential for ammonia volatilization in summer. The movement of transplanters through the field did not reducepNH₃, irrespective of floodwater depth (0 or 5 cm) and season. Harrowing and subsequent transplanter movement partially reducedpNH₃ in the summer;pNH₃ reduction, however, was greater when floodwater depth was 0 rather than 5 cm during harrowing and transplanting. This partial reduction ofpNH₃ in summer did not result in a corresponding increase in rice yield, presumably because N losses were only slightly reduced and because yield was constrained by additional factors, such as the adverse climate. In spring, the removal of floodwater before urea application and incorporation increased grain yield by 0.2 Mg ha^–1, even thoughpNH₃ was consistently low and was not reduced by urea incorporation. This result suggests that water management and tillage during basal urea application may influence rice growth and yield in ways other than reduced N loss.     

从机构的动态静力分析确定飞轮转动惯量

本文提出在作机构动态静力分析的同时确定飞轮转动惯量的简便方法。     

Path planning of multi-patched freeform surfaces for laser scanning

In this paper, a new method for scanning a complex surface model with multiple patches is proposed. In scanning of freeform-shaped models, it is difficult to generate a measuring plan by human intuition due to the complexity of the part. The developed method calculates the number of scans, scan direction, and scan path for a stripe-type laser scanner. The user can designate the surface patches that need to be scanned. In generating the scan plan, surface information is first extracted from the CAD model automatically. Other information such as, design knowledge, functionality and machine parameters are provided interactively. Based on this information, the original surface model is sampled in the u, v parameter domain and the sampled points are grouped using the view angle of the laser scanner. The scan direction is determined by calculating the global mean vector of the sampled points that belong to a group. The range of the view angle can be varied to enhance the quality of captured point data. The optical scan paths for each scan direction are calculated by projecting the sampled points onto a 2D plane. The optical constraints are also verified to guarantee the generated scan plan.     

Pyroelectric properties and X-ray photoelectron spectroscopic study of R.F. magnetron-sputtering-derived PZT thin films deposited on various interlayers

PZT thin films and interlayers were fabricated by the radio frequency (r.f.) Magnetron-sputtering from the Pb_1.1Zr_0.53Ti_0.47O₃, PbO and TiO₂ target. As a result of the XPS depth profile analysis, we can confirm that the substrate temperature affects the oxidation condition of each element of interlayers and the PZT film. Compared to the PZT/Pt structure, the dielectric and pyroelectric properties of PZT thin films inserted by interlayers were measured to a relatively high value. In particular, the PZT/PbO structure had the highest pyroelectric properties (P = 189.4 μC/cm²K; F _D = 12.7×10⁻⁶ Pa^−1/2; F _V = 0.018 m²/C).     

Effects of Mg dopant on the degradation of InGaN multiple quantum wells in AlInGaN-based light emitting devices

We investigated the effects of Mg dopant on the degradation of AlInGaN-based light emitting diodes (LEDs) and laser diodes (LDs) with InGaN multi-quantum wells (MQWs). Photoluminescence (PL) intensity of InGaN MQWs was significantly decreased with increasing the Mg intentional doping process in InGaN active region, indicating that Mg dopant could degrade the optical quality of InGaN MQWs. From secondary ion mass spectroscopy (SIMS) analysis of AlInGaN-based LDs grown on GaN/sapphire and GaN substrate with different dislocation densities, we found that Mg concentration of LD on GaN/sapphire was higher than that of LD on GaN substrate at the InGaN MQWs regions. Additionally, we observed that Mg atoms were significantly diffused from p-type layer to InGaN MQWs region in the LD structure after aging evaluation. From these results, we could conclude that Mg diffusion along threading dislocations is one of the major gradual degradation mechanisms of AlInGaN-based LD/LEDs during the device operation under high voltage condition.     

Fingerskate: Relaxing the Physical Constraint of Two-Finger Touchscreen Operations

Two-finger operations, such as rotation operations and zoom operations, are now standard touchscreen operations. However, these two-finger operations may pose an ergonomic problem when they are performed with one hand. FingerSkate is an interaction technique to mitigate the ergonomic problem of two-finger operations adopting the concept of gesture relaxation. A preliminary study showed that the FingerSkate technique was accepted well by the participants. In particular, a micro-analysis of finger movements during the study showed that FingerSkate was utilized well for large rotations. In a subsequent user study, the effects of two FingerSkate design options, Concurrency and Pivot, were examined. The Concurrency option had a statistically significant effect on performance and task workload for a docking task. The Pivot option had a statistically significant effect on task workload for a puzzle task. More participants preferred the sequential Concurrency option, and most participants preferred the center-of-object Pivot option.     

Transformation of a thin-walled solid model into a surface model via solid deflation

A simplified geometric model with lower dimensionality, such as a mid-surface model, is often preferred over a detailed solid model for the analysis process, if the analysis results are not seriously impacted. In order to derive a mid-surface model from a thin-walled solid model, in this paper, we propose a novel approach called the solid deflation method. In this method, a solid model is assumed to be created by using air to inflate a shell that comprises the surface of the solid model. First, the model is simplified by the removal of any detailed features whose absence would not alter its overall shape. Next, the solid model itself can be converted into a degenerate solid model with zero thickness. Finally, a surface model is generated by splitting large faces paired in the thinned solid model, selecting one face per pair for creating a sheet model, and sewing the selected faces. Using this method, a more practical and usable mid-surface model can be very efficiently generated from a solid model because it can circumvent not only the tedious trimming and extension processes of the medial axis transformation method but also the time-consuming patch joining process of the mid-surface abstraction approach.