Modular reactors with electrical resistance heating for hydrocarbon cracking and other endothermic reactions

We propose and demonstrate by calculations novel modular reactor configurations with electrical resistance heating for endothermic reactions such as cracking and steam reforming of hydrocarbons. The basic unit of each module consists of a set of wires, tubes, plates, monolith, or gauze/wire meshes arranged in parallel or series to satisfy the current–voltage constraints. The smaller dimensions such as spacing and diameter are selected to obtain nearly uniform heating temperature within the reaction zone.     

Hydrogen supply chain and challenges in large-scale LH2 storage and transportation

Hydrogen is considered to be one of the fuels of future and liquid hydrogen (LH2) technology has great potential to become energy commodity beyond LNG. However, for commercial widespread use and feasibility of hydrogen technology, it is of utmost importance to develop cost-effective and safe technologies for storage and transportation of LH2 for use in stationary applications as well as offshore transportation. This paper reviews various aspects of global hydrogen supply chain starting from several ways of production to storage and delivery to utilization. While each these aspects contribute to the overall success and efficiency of the global supply chain, storage and delivery/transport are the key enablers for establishing global hydrogen technology, especially while current infrastructure and technology are being under development. In addition, while all storage options have their own advantages/disadvantages, the LH2 storage has unique advantages due to the familiarity with well-established LNG technology and existing hydrogen technology in space programs. However, because of extremely low temperature constraints, commercialization of LH2 technology for large-scale storage and transportation faces many challenges, which are discussed in this paper along with the current status and key gaps in the existing technology.     

Pebbling of the skin: a marker of Hunter''s syndrome

Cancer patients typically experience fatigue while undergoing treatment for their disease. This study was an effort to identify a reliable and economical measure of fatigue. In particular, scores on the five subscales of the Multidimensional Fatigue Inventory (MFI-20) were analyzed for internal consistency and then correlated with scores on the Rhoten Fatigue Inventory to establish a measure of validity. Moderate-to-high Cronbach alphas coefficients were established for the General Fatigue subscale of the MFI-20 using a sample of 97 rural oncology outpatients (1). Partial associations with the Rhoten Fatigue Scale lend evidence to the validity of the MFI-20 measures.     

Robust and switched nonuniform scalar quantization of Gaussian source in a wide dynamic range of power

In this paper, robust and switched nonuniform scalar quantization model is analyzed for the case when the power of an input signal varies in a wide range. This model of scalar quantization is used in order to give higher quality by increasing signal-to-quantization noise ratio (SNRQ) in a wide range of signal volumes (variances) with respect to its necessary robustness over a broad range of input variances. We observed μ-low compandor implementation to achieve compromise between high-rate digitalization and variance adaptation. Accurate estimate of the input signal variance is needed when finding the best compressor function for a compandor implementation. It enables quantizers to be adapted to the maximal amplitudes of input signals. In addition, we found the expression for distortion, which we used to estimate the suggested model. In the nature of optimizing parameters of this model, we derived conclusions about the possibilities of this switched quantization application in speech processing. We analized influence of codebook size and number on quality of transmission, and compared ITU-T G711 standard with our model. The main contribution of this model is increasing of quality and the possibility of his applying for digitalization of continuous signals in wide range. The article is published in the original.     

Synthesis and characterization of multifunctional ZnO/polyester green composite films

In this study, we aim at facile fabrication of biodegradable polyester nanocomposite films with homogenous dispersion of ZnO nanoparticles. An environment friendly multi-functional biodegradable polyester resin has been synthesized using polyethylene glycol (PEG), lactic acid (LA) and maleic anhydride (MA) as monomers. ZnO nanoparticles were synthesized by hydrothermal method. As prepared nanoparticles were characterized by particle size analyzer, FE-SEM (Field emission scanning electron microscopy) and TEM (Transmission electron microscopy). Biodegradable ZnO/polyester composite films with 0.25, 0.50, 0.75 and 1.0 wt% of ZnO nanoparticles were fabricated by solution casting method. Experimental results revealed that incorporation of ZnO nanoparticles lead to substantial improvement in UV protection, antimicrobial behaviour and thermal stability, while retaining the biodegradable nature of the films.

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Performance analysis of selection diversity over exponentially correlated α– µ fading environment

An approach to the performance analysis of multibranch selection combiner (SC) receiver operating over fading channels is presented. High level of generality for the proposed analysis is achieved by considering correlated α– µ fading environment. The effect of correlation is studied by assuming exponential correlation model of the signals in each diversity branch. The whole analysis is observed in the interference‐limited fading environments (SIR‐based diversity system is assumed). The important performance measures are considered. Closed form of formulae for the output SIR's probability density function and cumulative distribution function are derived. In order to check the accuracy of the complete proposed formulation, some numerical results are presented. Copyright © 2011 John Wiley & Sons, Ltd.     

High-pressure optical studies of LMA:V

The effect of hydrostatic pressure on R line position and fluorescence lifetime τ for R line (²E → ⁴A₂ transition) in LMA:V²⁺ (LaMgAl₁₁O₁₉:V²⁺) was considered in the 0–100 kbar pressure range. Position of the R line is insensitive to pressure in the considered pressure range. Fluorescence lifetime τ linearly increases with pressure. τ has been calculated on the basis of the assumption that high pressure induces changes in compression rate k, oscillator strength f, spin-orbital coupling parameter ξ and refraction index n. The calculated τ agreed well with all the experimental data in the pressure range specified. The presented model provides a possible way of producing effect of high-pressure on R line fluorescence lifetime in LMA:V²⁺.     

YAP multi-crystal gamma camera prototype

The Anger camera principle has shown a practical limit of a few millimeters spatial resolution. To overcome this limit, a new gamma camera prototype has been developed, based on a position-sensitive photomultiplier tube (PSPMT) coupled with a new scintillation crystal. The Hamamatsu R2486 PSPMT is a 76-mm diameter photomultiplier tube in which the electrons produced in the conventional bi-alkali photocathode are multiplied by proximity mesh dynodes and form a charge cloud around the original coordinates of the light photon striking the photocathode. A crossed wire anode array collects the charge and detects the original position. The intrinsic spatial resolution of PSPMT is better than 0.3 mm. The scintillation crystal consists of yttrium aluminum perovskit (YAP:Ce or YAlO₃:Ce). This crystal has a light efficiency of about 38% relative to NaI, no hygroscopicity and a good gamma radiation absorption. To match the characteristics of the PSPMT, a special crystal assembly was produced by the Preciosa Company, consisting of a bundle of YAP:Ce pillars where single crystals have 0.6×0.6 mm² cross section and 3 mm to 18 mm length. Preliminary results from such gamma camera prototypes show spatial resolution values ranging between 0.7 mm and 1 mm with an intrinsic detection efficiency of 37÷65% for 140 keV gamma energy     

Radionuclide (MUGA) studies of left ventricular functional abnormalities in asymptomatic patients with sickle cell anemia

Radionuclide ventriculography was performed on 10 normal subjects and 39 patients with sickle cell anemia (10 homozygous and 29 heterozygous sicklers) at rest and after exercise. Their left ventricular (LV) function was assessed in both these situations. The results were then compared within the subgroups. The reduction in ejection fraction (EF) response (47.5 +/- 7 at rest and 46.4 +/- 8 at exercise in homozygous patients, and 52.4 +/- 8 at rest and 54.3 +/- 8 at exercise in heterozygous patients) was significant in both the homozygous and the heterozygous groups but more so in the former group. The diastolic filling was also significantly impaired in the homozygous group (PER 2.64 +/- 0.74, PFR 2.13 +/- 0.42 and PFR/HR 0.014 +/- 0.001). The study statistically demonstrates, that LV filling patterns are altered in the sickle cell patients, even in the absence of clinical symptoms relating to LV dysfunction. This fact may prove to be a marker of sickle cell heart disease. Frequent and significant sickling is probably the cause of more pronounced LV functional abnormalities in homozygous sicklers.     

An addressing technique for displaying restricted patterns in rms‐responding LCDs by selecting a few rows at a time

Abstract— An addressing technique that will allow rms‐responding matrix LCDs to display restricted patterns is proposed. This technique is based on the selection of a few rows at a time while scanning the display. In applications such as logic analyzers and oscilloscopes, mostly single‐valued functions of time are displayed. This restriction in the image is useful in enhancing the selection ratio so that good contrast is achievable even with TN‐LCDs. It is shown that a large reduction in the hardware complexity of the column drivers and the supply voltage is possible when the waveforms being displayed do not overlap each other and are equally spaced.