Sulfur capture for fluidized-bed combustion of high-sulfur content lignites

Sulfur release and capture behavior of lignites with highly combustible sulfur-contents were investigated by extending a previously-developed comprehensive model to incorporate sulfur retention. The predictive performance of the model was tested by comparing the model predictions with on-line concentration measurements of O₂, CO₂, CO and SO₂. Favorable comparisons are obtained between the predicted and measured concentrations of gaseous species along the combustor. Results show that freeboard sulfur-capture is enhanced significantly with recycling of elutriated sorbent particles as the sulfur release to the freeboard is significant for fuels rich in combustible sulfur.     

A fast tool servo design for precision turning of shafts on conventional CNC lathes

A technique for precision turning of shafts on conventional CNC turning centers is presented. The shaft is semi-turned on a conventional CNC lathe. The precision finish turning operation is delivered by a piezoelectric based fast tool servo which is mounted on the same CNC lathe's turret. The precision tool tip motion is delivered by a proposed sliding mode controller which is robust to changes in the cutting process and hysteresis in the piezo actuator. Sliding mode controller is also quick to compensate the cutting force disturbances, and keeps the tool tip at the desired location within the displacement measurement sensor resolution (±0.1 μm). The fast tool servo system is packaged in a PC, and its effectiveness is demonstrated on a bearing location turning.     

Synthesis and characterization of two-armed poly(ɛ-caprolactone) polymers initiated by the Schiff's base complexes of copper(II) and nickel(II)

Two-armed poly(?-caprolactone) (TAPCL) polymers were successfully synthesized via the ring opening polymerization (ROP) of ?-caprolactone (?-CL) using the Schiff's base complexes [Cu(SAEE)₂] (1) and [Ni(SAEE)₂] (2), which have two hydroxyl functional groups, as the two-site initiators and tin(II) 2-ethylhexanoate (Sn(Oct)₂) as the catalyst in bulk at 115 °C. The Schiff's base complexes (1 and 2) were synthesized by utilizing the concentrated template synthesis method starting from salicyl aldehyde, 2-(2-aminoethoxy) ethanol and related metal acetate salts. The synthesized TAPCL polymers were characterized by GPC, FTIR, UV–vis, and electron paramagnetic resonance (EPR). The molecular weights of TAPCL polymers linearly increased with increasing molar ratio of the monomer to the initiator. The results obtained from FTIR, UV–vis, and EPR studies indicated that TAPCL polymers had the Schiff's base complexes at the junction point of PCL arms. The crystallization behavior of TAPCL was studied by using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Thermal behavior of TAPCL was also investigated by thermogravimetrical analysis (TGA).     

CMOS realization of two-dimensional mixed analog-digital Hamming distance discriminator circuits for real-time imaging applications

The architecture of an integrated Hamming artificial neural network, and its use as a versatile signal/image processing circuit is presented. The circuit operation relies on the charge-based processing of sum-of-products terms, complemented with digital post-processing. The synthesis of complex functions such as winner-(loser)-take-all, k-winner-(loser)-take-all, rank ordering are demonstrated with a minimal hardware overhead. Different operation modes and corresponding hardware configurations are presented. The VLSI realization of the core two-dimensional Hamming distance discriminator, and the chip measurements are discussed. As such, the presented Hamming discriminator is uniquely suitable for real-time image processing and alignment applications.     

Further experimental evidences of the compatibility of poly(vinyl acetate) with poly(ethyl methacrylate) and its dependence on the ratio of the molecular weight of the two homopolymers

Using various fractions of poly(ethyl methacrylate) (PEMA) and poly(vinyl acetate) (PVAc) of very narrow molecular weight distribution, a very wide range of 2–120 of molecular weight ratio M¯_ν PEMA/M¯_ν PVAc, (M¯_ν)_r was obtained. Studies of some tensile mechanical properties of films of the blends produced from solution on mercury confirmed strong dependence of the improvements of PVAc properties for blend with 18% PEMA on (M¯_ν)_r, especially in the range 5 ≤ (M¯_ν)_r < 100. The density of the films of the blend was much higher than those of the individual polymers and increased monotonically with (M¯_ν)_r. Optical micrographs of the films of the blends showed interactions between the two polymers with 18% PEMA composition, which appears to be more intimate as (M¯_ν)_r increases, as further evidence of compatibility and miscibility of the two polymers.     

Comparative study of a variety of ATRP systems with high oxidation state metal catalyst system

MMA (methyl methacrylate) was polymerized in different ATRP systems using the different ligands of HMTETA (1, 1, 4, 7, 10, 10, hexamethyltriethylenetetraamine), TMEDA (N,N,N′,N′-Tetramethylethylenediamine) with copper salts (CuBr/CuBr₂) and EBriB was used as an initiator in toluene at a reaction temperature of 80 °C. Both conventional and a low catalyst to initiator ratios ranging from 1/1 to 0.01/1 were compared in this study. All four of the ATRP methods, such as normal, reverse, AGET and ATRP using a high oxidation state metal complex without any additives, were evaluated at different conditions. The ATRP using a high oxidation state metal system in the absence of a conventional radical initiator like AIBN, which is used in reverse ATRP, or reducing agents such as Sn (EH)₂ in AGET ATRP was a better controlled system in terms of both the catalytic activity and controllability (PDI ∼ 1.2).     

Deposition and Characterization of Si Substituted Cu2ZnSnS4 Thin Films

Silicon - The influence of the Si substitution ratio on the structural, morphological, and optical properties of Cu2ZnSnS4 (CZTS) thin films was examined. The Cu2Zn(SixSn1–x)S4 thin films...