Air gasification of dried sewage sludge in a two-stage gasifier. Part 2: Calcined dolomite as a bed material and effect of moisture content of dried sewage sludge for the hydrogen production and tar removal

In order to produce a clean producer gas, the air gasification of dried sewage sludge was conducted in a two-stage gasifier that consisted of a bubbling fluidized bed and a tar-cracking zone. The kind and amount of bed materials, the kind of additives in the upper-reactor, and the moisture content in the sewage sludge were selected as operating variables in order to investigate their effects on the development of the producer gas characteristics. In our experiments, the gasification of a dried sewage sludge sample containing 30 wt.% of moisture with a combination of calcined dolomite as the bed material and activated carbon in the tar-cracking zone removed the most tar and produced the highest hydrogen concentration. The total tar removal efficiency and the H₂ content in the producer gas from the sample noted above reached 88.4% and 32.1 vol.%, respectively. The LHVs of all the producer gases were high with values above 7 MJ Nm⁻³.     

A wide-view twisted nematic liquid crystal cell with improved image quality obtained by decreasing γ-curve distortion

Wide-view (WV) film, which was introduced by Fuji Co., has been commercialized to block light leakage of twisted nematic (TN)-liquid crystal (LC) cells in a dark state when the viewing angles are in the off-axis direction. In this investigation, we designed an optical compensation structure of a TN-LC cell with an improved γ-curve, as well as a viewing angle property in the dark state. Basically, we used a pair of optical films consisting of a positive and a negative A-plate in order to avoid affecting the viewing angle property in the dark state. Then, we optimized the positive and negative A-plate to improve the viewing angle property in the gray levels by calculating polarization variations as a function of the optical axis and the retardation of the pair of the A-plates. From this calculation, we were able to show that the proposed normally white (NW) WV-TN cell exhibits wide viewing angle performance, including good γ-curve stability.     

Effect of molecular structure on performance of electroactive ionic acrylic copolymer–platinum composites

The character and performance of a new ionic polymer–metal composite (IPMC) prepared with a melt‐processable fluorinated acrylic copolymer were examined. The fluorinated acrylic copolymer was synthesized by the copolymerization of fluoroalkyl methacrylate (DuPont Zonyl) and acrylic acid, and it was compression molded to attain membranes of various thicknesses. The current and displacement responses by electric stimulus were measured to study the effects of the ionic concentration, thickness, and countercation on the actuation of the IPMC. The ionic center of the acrylic copolymer was essential for the actuation of the IPMC; however, too much ionic center induced excessive water uptake, which caused adverse effects on the performance of the IPMC. When the applied voltage was 5 V, the largest current and displacement responses were observed with the IPMC prepared by a fluorinated acrylic copolymer containing 11.8 wt % acrylic acid. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1732–1739, 2005     

Technology improvements for image-guided and minimally invasive spine procedures

This paper reports on technology developments aimed at improving the state of the art for image-guided minimally invasive spine procedures. Back pain is a major health problem with serious economic consequences. Minimally invasive procedures to treat back pain are rapidly growing in popularity due to improvements in technique and the substantially reduced trauma to the patient versus open spinal surgery. Image guidance is an enabling technology for minimally invasive procedures, but technical problems remain that may limit the wider applicability of these techniques. The paper begins with a discussion of low back pain and the potential shortcomings of open back surgery. The advantages of minimally invasive procedures are enumerated, followed by a list of technical problems that must be overcome to enable the more widespread dissemination of these techniques. The technical problems include improved intraoperative imaging, fusion of images from multiple modalities, the visualization of oblique paths, percutaneous spine tracking, mechanical instrument guidance, and software architectures for technology integration. Technical developments to address some of these problems are discussed next. The discussion includes intraoperative computerized tomography (CT) imaging, magnetic resonance imaging (MRI)/CT image registration, three-dimensional (3-D) visualization, optical localization, and robotics for percutaneous instrument placement. Finally, the paper concludes by presenting several representative clinical applications: biopsy, vertebroplasty, nerve and facet blocks, and shunt placement. The program presented here is a first step to developing the physician-assist systems of the future, which will incorporate visualization, tracking, and robotics to enable the precision placement and manipulation of instruments with minimal trauma to the patient.     

Preliminary comparative studies of zinc and zinc oxide electrodes on corrosion reaction and reversible reaction for zinc/air fuel cells

Even though Zn/air energy system is considered to be a promising power energy source, it has been limited to be applied for an electrically rechargeable system basically due to the problem of the irreversible reaction and the corrosion reaction. In this paper a novel attempt has been made to compare the behavior of zinc electrode with a zinc oxide electrode and a modified zinc oxide electrode containing zinc oxide and lead oxide. The hydrogen overpotential is favorable in the zinc electrode, and the modified zinc oxide electrode shows the improved properties showing the more negative potential than the case of the zinc oxide electrode. Investigations of cyclic voltammogram reveal that the pure zinc electrode is irreversible, while both the zinc oxide and the modified zinc oxide electrodes are reversible. However, as far as dendrite formation is concerned there is no marked improvement in case of the zinc oxide and the modified zinc oxide electrodes.     

Speeding up Scalar Multiplication in Genus 2 Hyperelliptic Curves with Efficient Endomorphisms

This paper proposes an efficient scalar multiplication algorithm for hyperelliptic curves, which is based on the idea that efficient endomorphisms can be used to speed up scalar multiplication. We first present a new Frobenius expansion method for special hyperelliptic curves that have Gallant‐Lambert‐Vanstone (GLV) endomorphisms. To compute kD for an integer k and a divisor D, we expand the integer k by the Frobenius endomorphism and the GLV endomorphism. We also present improved scalar multiplication algorithms that use the new expansion method. By our new expansion method, the number of divisor doublings in a scalar multiplication is reduced to a quarter, while the number of divisor additions is almost the same. Our experiments show that the overall throughputs of scalar multiplications are increased by 15.6 to 28.3 % over the previous algorithms when the algorithms are implemented over finite fields of odd characteristics.     

A New Blind Beamforming Procedure Based on The Conjugate Gradient Method for CDMA Mobile Communications

The objective of this paper is to present an adaptive algorithm for computing the weight vector which provides a beam pattern having its maximum gain along the direction of the mobile target signal source in the presence of interfering signals within a cell. The conjugate gradient method (CGM) is modified in such a way that the suboptimal weight vector is produced with the computational load of O(16N), which has been found to be small enough for the real-time processing of signals in most land mobile communications with the digital signal processor (DSP) off the shelf, where N denotes the number of antenna elements of the array. The adaptive procedure proposed in this paper is applied to code division multiple access (CDMA) mobile communication system to show its excellent performance in terms of signal to interference plus noise ratio (SINR), bit error rate (BER), and capacity, which are enhanced by about 7 dB, times, and 7 times, respectively, when the number of antenna elements is 6 and the processing gain is 20 dB.     

Tissue levels of malondialdehyde after passive smoke exposure of rats for a 24-week period.

The present study was to evaluate the effects of chronic cigarette smoke exposure on lipid peroxidation in various organ tissues. Sprague-Dawley rats were exposed to passive smoking 2 hr per day, 6 days per week (Monday-Saturday), for 24 weeks. Malondialdehyde levels, as an index of lipid peroxidation, were measured by the thiobarbituric acid assay. Levels were significantly higher in tissues of passive-smoke-exposed groups (n=10) compared with normal-bred control groups (n=6), for red blood cells (2.17+/-0.22 vs. 1.80+/-0.39 nmol/mg), lung (1.39+/-0.32 vs. 1.03+/-0.35 nmol/mg), and spleen (1.75+/-0.33 vs. 1.42+/-0.15 nmol/mg); p<.05. No differences in malondialdehyde levels were found in plasma, heart, liver, stomach, and renal tissues. The results suggest that chronic environmental tobacco smoke exposure can increase lipid peroxidation in red blood cells and in lung and spleen tissue. This finding brings further investigative attention to the public health issue of the injurious effects of chronic passive smoke exposure.     

Electron microscopy study on the grain-boundary precipitation during aging of Fe-10Ni-5Mn steel

In order to determine the mechanism of grain-boundary embrittlement and de-embrittlement in age-hardened Fe-Mn-Ni alloys, a detailed analysis on the grain-boundary precipitation behavior was conducted using electron diffraction and electron energy loss spectroscopy (EELS) techniques. The precipitation of θ-MnNi intermetallic particles as well as the precipitation of the austenite phase at prior austenite grain boundaries in association with the grain-boundary embrittlement was confirmed. Interlath fracture was also observed with the precipitation of θ-MnNi particles at the interlath boundaries. The de-embrittlement of these boundaries appears to be a result of the conversion of the θ-MnNi phase to a more ductile austenite phase after extended aging.