Complexity‐Reduced Algorithms for LDPC Decoder for DVB‐S2 Systems

This paper proposes two kinds of complexity‐reduced algorithms for a low density parity check(LDPC) decoder. First, sequential decoding using a partial group is proposed. It has the same hardware complexity and requires a fewer number of iterations with little performance loss. The amount of performance loss can be determined by the designer, based on a tradeoff with the desired reduction in complexity. Second, an early detection method for reducing the computational complexity is proposed. Using a confidence criterion, some bit nodes and check node edges are detected early on during decoding. Once the edges are detected, no further iteration is required; thus early detection reduces the computational complexity.     

Controlled release of bovine serum albumin using MPEG–PCL diblock copolymers as implantable protein carriers

MPEG–PCL diblock copolymers consisting of methoxy polyethylene glycol (MPEG) and poly(?‐caprolactone) (PCL) as drug carriers were synthesized by ring‐opening polymerization. It is possible to control the balance between hydrophilic and hydrophobic by changing the MPEG and the ratio of ?‐CL to MPEG. Implantable wafers were easily fabricated by the direct compression method after physical mixing of diblock copolymers and bovine serum albumin–fluorescein isothiocyanate (BSA‐FITC) as a model protein drug. The BSA release from wafers prepared by MPEG–PCL diblock copolymers were higher than that from PCL with the physical blending of MPEG. The wafers prepared by a variety of MPEG–PCL diblock copolymers exhibited the controlled BSA release profiles with a dependence on MPEG–PCL diblock copolymer compositions. In addition, the changing of MPEG and PCL molecular weights within MPEG–PCL diblock copolymer controlled the initial burst of BSA. We confirmed that the diblock copolymers could be served as protein delivery carrier in implantable wafer form. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:1561–1567, 2006     

Design of Scannable Non‐uniform Planar Array Structure for Maximum Side‐Lobe Reduction

In this letter, we propose a novel design scheme for an optimal non‐uniform planar array geometry in view of maximum side‐lobe reduction. This is implemented by a thinned array using a genetic algorithm. We show that the proposed method can maintain a low side‐lobe level without pattern distortion during beam steering.     

Study on InGaAsP-InGaAs MQW-LD with symmetric and asymmetric separate confinement heterostructure

We studied symmetric and asymmetric InGaAsP-InGaAs 1.55-/spl mu/m multiquantum-well (MQW) laser diodes (LDs) with highly p-doped layers in the two-step separate confinement heterostructure (SCH). The p-doping in p-SCH suppresses the electron overflow from the MQWs to p-SCH, but it is an origin of free carrier absorption loss. An additional InGaAsP layer inserted inside n-SCH makes asymmetric field distribution and, therefore, reduces the portion of optical field distribution in highly p-doped regions with high optical loss. Compared with symmetric structure, asymmetric SCH LD has low threshold current density, low internal loss, and high and flat slope efficiency with respect to temperature.     

Separation of whey proteins by anion-exchange membranes

Three strong anion-exchange membranes (CIM QA, Q100 and HiTrap Q) were investigated for the separation of the major proteins, which were contained in whey, such as α-Lactalbumin, BSA and β-Lactoglobulin. Experiments were performed to determine the optimum mobile phase composition for separating the whey proteins using the standard chemicals of the proteins. The mobile phase was buffer A (20 mM piperazine-HCl pH 6.4) and buffer B (buffer A+1 M NaCl) and the linear gradient elution changes of salt concentration were applied. The standard chemicals of the proteins were used to investigate the optimal mobile phase compositions with the three anion-exchange membranes. From the experimental results, it was found that HiTrap Q was the most effective in separating whey proteins.     

Enhanced brightness and efficiency of organic light-emitting diodes with an LiF in the Alq/sub 3/

Highly efficient and bright organic light-emitting diodes have been realized by inserting a thin insulating lithium fluoride (LiF) layer in the tris-(8-hydroxyquinoline) aluminum (Alq/sub 3/) with conventional organic layers. By comparing the performances of newly devised devices as a function of the position of the LiF in the Alq/sub 3/ layer, the authors propose the optimal position of the LiF in the Alq/sub 3/ layer. Experimental results show that the efficiency and brightness of the newly devised device with LiF in the Alq/sub 3/ layer were seven times higher than that without LiF in the Alq/sub 3/ layer.     

Molecular design,synthesis, and electro‐optic properties of novel Y‐type polyesters with high thermal stability of second harmonic generation

3,4‐Di‐(2′‐hydroxyethoxy)‐4′‐nitrostilbene was prepared and condensed with terephthaloyl chloride, adipoyl chloride, and sebacoyl chloride to yield novel Y‐type polyesters containing NLO‐chromophore dioxynitrostilbenyl groups, which constituted parts of the polymer backbone. Polymers were found soluble in common organic solvents such as acetone and N,N‐dimethylformamide. They showed thermal stability up to 300 °C in thermogravimetric analysis with glass‐transition temperatures obtained from differential scanning calorimetry in the range 110–152 °C. The second harmonic generation (SHG) coefficients (d₃₃) of poled polymer films at a 1064 cm^?1 fundamental wavelength were around 3.51 × 10^?8 esu. The dipole alignment exhibited high thermal stability even at 10 °C higher than the glass‐transition temperature, and there was no SHG decay below 120 °C for one of these polymers due to the partial main‐chain character of polymer structure, which was acceptable for NLO device applications. Copyright © 2005 Society of Chemical Industry     

Application of computational fluid dynamics analysis for improving performance of commercial scale selective catalytic reduction

The performance of commercial scale selective catalytic reduction (SCR) system is strongly dependant upon the degree of mixing between NH₃ and NOx or NH₃ concentration distribution at the catalyst layer according to the reaction kinetics of SCR catalysts. Insufficient mixing of the reduction agent and NOx mass flow necessitates an uneconomically large catalyst volume and high NH₃ slip to meet the required NOx emission values. The effective methodology which can increase the performance of commercial scale SCR through improving NH₃ concentration distribution at the catalyst layer using computational fluid dynamics (CFD) analysis was suggested and applied to the real operations. The operation results have shown that the performance of commercial SCR was improved from 54.4% to 74.8% as NH₃ concentration deviation at the catalyst layer was reduced from 23.6% to 8.6%. It is established that the increase of NH₃ concentration uniformity at the catalyst layer contributes to improvement of performance of commercial scale SCR.     

Preparation and characterization of vanado-, ferri-, and gallosilicate catalysts in the presence of fluoride ions

Vanado-, ferri-, and gallosilicate catalysts were prepared from the mixtures containing colloidal silica, corresponding metal source, tetrapropylammonium bromide, and NH₄F by hydrothermal crystallization at 175°C for 7 days. The pH value of the reaction mixture was low (pH<8) compared to the conventional methods. The metal compounds have higher solubilites in these conditions than conventional conditions (pH>10). The size distribution and the size of final products were found to be more homogeneous and larger than those of metallosilicates prepared in strong alkaline media. The characterization of metallosilicates with IF!, X-ray diffraction, SEM, EPR, and²⁹Si MAS NMR, indicated that corresponding metal atoms were successfully incorporated into the tetrahedral lattice sites of the ZSM-5 structure.