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An orthogonal frequency division multiplexing (OFDM) is one of the effective techniques used in wireless communications. In OFDM systems, channel impairments due to multipath dispersive wireless channels can cause deep fades in wireless channels. The OFDM receiver also requires an accurate and computationally efficient channel state information when coherent detection is involved. Therefore, it needs a good robust estimation method of the channel in wireless communication for OFDM systems. And one of these channel estimation methods is minimum mean square error (MMSE) channel estimation. MMSE channel estimation one most used method in OFDM systems. In this work we enhanced robustness of MMSE channel estimation by using it in base of quasi-cyclic low density parity check (QC-LDPC) coded OFDM system.

Mixed reactive disperse dyes is adopted to dye wool yarn by supercritical CO2 dyeing equipment, and the influencing factors on the wool yarn uptake are analyzed including dyeing temperature, dyeing time, dyeing pressure. The results reveal the interaction relationship between single dyes dyeing on the wool yarn: the total uptake of mixed reactive disperse dyes and the uptake of single reactive disperse dyes increase with the increasing of temperature and pressure, it also increase by the extension of time. In the same conditions, the total uptake of mixed reactive disperse dyes is more than the uptake of single reactive disperse dyes. The uptake of single reactive disperse dyes in the mixed dyes is less than the uptake of single reactive disperse dyes. In the dyeing process of mixed dyes, the wool yarn dyeing of two dyes has selective and competitive. Both color fastness to rubbing and color fastness to washing of dyed wool yarn are in line with national institute of standards.

The conventional process for isobornyl acetate synthesis from camphene and acetic acid is a batch process. The purpose of this paper is to synthesize isobornyl acetate in continuous process in a fixed bed reactor. The continuous reaction conditions were studied. The experiment was put into practice under the following conditions: 35-45, camphene/acetic acid feed ratio(wt%) from 1 to 2 and space velocity from 0.6 to 1.8 h-1. A kinetic model was developed which describes the experimental data well. A pilot fixed reactor was simulated by using the kinetic model.

A series of SAPO-34 materials were synthesized hydrothermally in the presence of mixed templating agent (named TEDE) of tetraethyl ammonium hydroxide (TEAOH) and diethylamine (DEA). The effects of template amount, SiO2/Al2O3 and P2O5/Al2O3 molar ratios and the crystallization temperature on the structure and acidity were studied by XRD, nitrogen adsorption and NH3-TPD techniques. The results showed that SAPO-34 and SAPO-5 are competing phases at low template concentration. Pure SAPO-34 with high crystallinity and large BET surface area were obtained at a TEDE/Al2O3 ratio of 2.0. Varying the SiO2/Al2O3 ratio at 0.1~1.0 did not change the purity of SAPO-34, but affected its crystallinity and acidity. An optimal synthesis procedure giving a homogeneous SAPO-34 framework with high crystallinity, consists of heating a gel of composition Al2O3:P2O5:0.6SiO2:1.0TEAOH:1.0DEA:53H2O at 100 °C for 24h firstly and 200 °C for 72h later. Such a reproducible procedure gave rise to an acidic catalyst active in the MTO reactions with 100% methanol conversion, 85.2% ethylene and propylene selectivity and a longest lifetime.

With incipient impregnation method, cobalt-based catalysts were prepared. The effects of the ZrO2 modification of support and the addition of the second metal Ru on heavy hydrocarbon synthesis were investigated in a fixed-bed reactor. The results revealed that, in cobalt-based catalysts modified with ZrO2, cobalt species were presented in the form of Co3O4, Zr species were highly dispersed or amorphous on the surface of the catalysts. ZrO2 addition also increased the desorption amount of CO, which was correlative with the degree of reduction of cobalt species. When the catalysts modified with ZrO2, the strong interaction between Co species and γ-Al2O3 support was replaced by a weak interaction between Co species and ZrO2. The ZrO2 modification increased the amount of easily reducible Co species. It is noteworthy that addition of a small quantity of Ru promoted the reduction of cobalt species, which led to the reduction temperature decreasing. For the 15w%Co0.4w%Ru4.3w%ZrO2/γ-Al2O3, at a reaction condition as feed gas ratio n(H2):n(CO)=2.0, 483K, 1.5MPa and 800h-1, the conversion of CO was 76.98 %, the selectivity of C5+ 88.36 %, the chain growth probability 0.86, and as to 15.0%Co0.4%Ru/γ-Al2O3, the conversion of CO was 67.15%, the selectivity of C5+ 84.41% and the chain growth probability 0.84.