Effect of high temperature alkali cooking on the constituents,structure and thermal degradation of hemp fiber

Degumming of hemp fiber by high temperature alkali cooking was investigated, and the effect of temperature and dosage of alkali on the constituents, structure, and thermal degradation of hemp fiber was also discussed in this work. The morphology, structure, and thermal degradation of hemp fiber after high temperature cooking were investigated through SEM, FTIR, WAXD, and TG analysis. The results indicated that the high temperature cooking process was effective for removing hemicelluloses and lignin and could also improve the thermal stability of cellulose. Crystallinity index of the treated hemp fiber was increased, which was related to the cooking temperature and NaOH dosage. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Structure and processability of iodinated poly(vinyl alcohol). IV. Drawability of the films iodinated at solution before casting

The drawability of iodinated at solution before casting (IBC) polyvinyl alcohol films prepared by casting aqueous solutions of 10 wt % PVA containing 15.2, 39.8, 83.2, 117.0, and 140.1% was examined with a tensile tester at 20–60°C. The tensile behavior of IBC films showed that the yield and breaking loads were much lower, and the breaking elongation was even higher than those of the unoriented iodinated after casting (IAC) films as well as the untreated PVA films. The maximum draw ratios of the films with the weight gain of 15.2, 39.8, 83.2, 117, and 140.1% were 4.5, 5.5, 8.5, 8.0, and 7.5, respectively, which were achieved at 20°C in all. The crystallinity of all films increased by the maximum draw, regardless of crystallinity before drawing. The crystalline structure was recovered to the original PVA crystalline lattice by deiodination. Amorphous orientation and initial moduli increased with the maximum draw ratio, while the orientation of crystals was constant. The orientation and moduli increased up to the weight gain of 83.2%, whose highest draw ratio and initial modulus were 8.5 and of 7.1 GPa, respectively, and then decreased. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

A study on dynamic friction of different spun yarns

This article presents the results from a study of yarn-to-yarn (YY) and yarn-to-metal (YM) frictions conducted on ring, rotor, air-jet, and open-end friction (OE friction) spun yarns at different relative speeds and input tensions. The results indicate that the behavior of frictions for YY is different than that of YM. In case of YY friction, OE friction yarn shows maximum friction followed by rotor, air-jet, and ring spun yarns; however, a reverse order is noticed for YM friction. The relative speed and input tension have significant influence on the frictional behavior of spun yarns. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

2D artificial life system using network-type assembly-like language: influence of change in environment with costs of instructions

To unlock the full potential of evolution in digital media, a Tierra-like system using network-type assembly-like language has been constructed. In the system, like Avida, digital creatures, self-replicating programs, live in a discrete 2D torus space and an interaction between creatures is restricted locally. Bearing a genetic network in mind, network structure is introduced. In the previous works, it is shown that the possibility that the network-type model has more potential of evolution than a linear-type model like Avida in a simple environment. In this paper, to study the potential of evolution more precisely, we model the effects of environment other than creatures. As one of the simplest models of such environment, the cost of execution, i.e. executing time, is introduced. The difficult environment to live in costs high to execute instructions, the easy environment does low. In computer experiments, we have investigated the influence of change in environment by analyzing the process of evolution and diversity of the system. Experimental results show that the network-type system keeps more stable diversity than the linear-type system does, even when the environment changes drastically. This indicates the possibility that the network-type system has more potential of evolution than the linear-type system has. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Syntheses and Structural Characterization of Triorganotin Derivatives of Bis(carboxymethyl)trithiocarbonate: X-ray Crystal Structures of 2D Network Polymers

Six triorganotin(IV) complexes of the type {(R₃Sn)₂[C₃S₃(COO)₂]}_n (R = C₆H₅ 1; n-Bu 2; PhCH₂ 4; p-F-PhCH₂ 5; o-F-PhCH₂ 6) and {(R₃Sn)₂[C₃S₃(COO)₂]}_n·[EtOH] (R = Me 3) have been synthesized by the reaction of bis(carboxymethyl)trithiocarbonate with triorganotin(IV) chloride in the presence of sodium ethoxide. All complexes were characterized by elemental analysis IR, ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopy. Except for 4–6, all complexes were also characterized by X-ray crystallography. The X-ray date revealed that complexes 1–3 show two-dimensional network polymeric structure in which the geometries of tin atoms are trigonal bipyramid with the axial positions occupied by carboxylic oxygen atoms.     

Pulsating Jet Impingement Heat Transfer Enhancement

This article presents results from a numerical study of pulsating jet impingement heat transfer. The motivation is to seek conditions offering a significant enhancement compared to steady flow impingement drying. The CFD software package FLUENT was used for simulating slot-type pulsating jet impingement flows with confinement. The parameter study included velocity amplitude ratio, mean jet velocity, and pulsation frequency. The distance from nozzle exit to surface was three times the hydraulic diameter of the nozzle. The Reynolds number based on the nozzle hydraulic diameter and jet temperature was 2,460 with a mean jet velocity of 30 m/s, which is the base case of the numerical experiments. Results showed that time-averaged surface heat transfer increased with increasing velocity amplitude for the same mean jet velocity. Large velocity amplitudes helped enhance heat transfer by two mechanisms: high jet velocity during the positive cycle and strong recirculating flows during the negative cycle. For the cases with different mean jet velocities but the same maximum velocity, time-averaged surface heat flux decreased with decreasing mean jet velocity. As for the effects of pulsation frequency, with high-velocity amplitude ratio, time-averaged surface heat fluxes were at the same level regardless of frequency. However, at low-velocity amplitude ratio, high frequency caused stronger recirculating flows resulting in greater heat transfer compared to the cases with a lower frequency.     

罗坡坝水电站泄水建筑物设计及试验研究

罗坡坝水电站拱坝设置有三个溢流表孔,中间孔高程低于两侧的孔,三个泄水孔设有差动式挑坎。通过模型试验表明,不发生危及岸坡稳定的泄流雾化问题,此外,适当控制泄流水舌射程可以减少坝下冲坑深度,消能效果良好。     

光纤智能复合材料

对光纤型智能复合材料的工作原理，性能特点和应用前景作了介绍，并讨论了制造成型的技术问题。     

Analysis of polarization plane rotation characteristic in 2D photonic crystal waveguide with chiral medium by condensed node spatial network

Using the photonic band gap in photonic crystals, the fundamental waveguide structures for the light wavelength range have been developed. Based on the fine structure of these many functional devices have been proposed by analytical or numerical simulation methods and the experiments of trial manufacture. In this paper, the treatment of chiral dielectric in the Condensed Node Spatial Network for the vector potential is explained, and we show the polarization plane rotation property in air‐hole and pillar type photonic crystal waveguide structures with the chiral medium substrate. Then, we show the fundamental advantage of the air‐hole type photonic crystal waveguide structure in application to a mode converter. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(1): 7–14, 2005; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20098