Characterization of coal products from high temperature processing of Usibelli low-rank coals

This research project was conducted in association with Gilbert/Commonwealth Inc. as part of an overall techno-economic assessment of high temperature drying of low-rank coals. This report discusses the characteristics of the dried/pyrolyzed products of two high temperature, evaporative processes and the dried product from a hydrothermal process. The long term goal of this and other coal drying studies conducted at MIRL, was to define drying technologies that have significant and real potential to competitively move Alaska's, low-rank coals (LRCs) into the export, steam coal market of the Pacific Rim. In 1990, Japan imported 33 million metric tons (mt) of steam coal with an additional 39 million mt imported by other Far East nations(2). Australia dominates the export steam coal market to these Pacific Rim countries and exported 48 million mt in 1990 and an additional 61 million mt of metallurgical coal(2). The worldwide steam coal export market has been expanding rapidly, from 20 million mt in 1973 to 150 million mt in 1989, and is expected to double to nearly 300 million mt by the end of the century(3). Could Alaska capture only 3% of the projected new world steam coal market, which is not an unreasonable expectation, the value of the state's coal exports would soar from nominally $28 million per year to over$100 million per year. However, without development of economical methods for drying/stabilizing Alaskan LRCs, the only increase in export of Alaskan coals may be from the few "higher rank" coals within a "reasonable" transport range of the existing Alaska rail system or tidewater. Presently the coal from the Usibelli Coal Mine is the only low-rank coal exported internationally as a steam coal; primarily for its blending properties with other coal to improve combustion. But for Alaskan low-rank coals to truly stand on their own merits, economical drying processes must be developed that produce a physically and chemically stable dried product. The technologies that have the most potential for increasing the use of Alaskan coals are those that can reduce the moisture content of these coals economically, and produce a fuel that is accepted in the international market place. Drying technologies will no doubt differ, depending on the end use of the fuel; be it dried lump coal, briquettes or pellets for pulverized coal or stoker applications, or concentrated coal-water fuels made from hot water dried LRCs. There are a number of developing processes that may work with Alaskan coals. Some drying processes, however, have been plagued by the production of excessive amounts of coal fines, Since the demand for Alaskan coal is currently limited to lump size coal, large quantities of fines are a definite liability. In this study, two high temperature drying/pyrolysis processes and one hydrothermal process were investigated. The high temperature drying/pyrolysis processes were conducted at (1) the Western Research Institute, (WRI) an affiliate of the University of Wyoming Research Corporation, Laramie, WY, and (2) Coal Technology Corporation (CTC) of Brisol, VA. Hydrothermal processing was conducted at MIRL, University of Alaska Fairbanks. A summary of these processes and the products they produced follows.The University of Alaska also provided matching funds for this project, which was a portion of a larger study that leveraged U.S. Department of Energy funds

Effect of lamellar microstructure on the permeability of polyethylene films

Lamellar microstructures can decrease the permeability to gases and vapors by increasing the diffusive path in plastic films, or the so-called tortuosity which depends on the aspect ratio, orientation, and the volume fraction of the dispersed material. In this research, different types and percentages of mica with relatively high aspect ratio are used as oxygen barrier materials in blown films. Both high and low density polyethylenes (HDPE and LDPE), as well as their blends are used as the matrix materials. A decrease in permeability of both LDPE and HDPE films to oxygen is achieved with increasing volume fraction of the higher aspect ratio mica. By contrast, use of the coarser mica grades did not result in the anticipated properties in HDPE films. In all cases, the morphology of the films corresponded to several overlapping, discontinuous mica layers with the broad faces of mica, essentially parallel to the surface of the films. Rheological properties, morphology, and mechanical properties were also examined. The experimentally determined permeability and elastic modulus values were found to be in good agreement with theoretical predictions. By contrast to LDPE, the processability of HDPE films was found to decrease dramatically with increasing mica loadings, It was found that optimization of barrier properties in HDPE films through addition of mica flakes is a compromise between the desired reduction in permeability and the loss in processahility and ductility

Solution treatment of vacuum high pressure die cast aluminum alloy A380.

High pressure die castings usually contain gas porosity mainly due to the entrapment of air or gas during melting due to very high speed injection of the molten metal into the cavity. Vacuum high pressure die casting technology has been proven to be an effective way of reducing gas porosity and pore sizes in castings. As a result, density and mechanical properties, particularly tensile strength and ductility, were improved markedly, and also make castings heat treatable. An investigation on the effect of solution heat treatment in high pressure vacuum die casting A380 alloy has been carried out using methods of microhardness measurement, tensile testing, optical, scanning electron microscopy (SEM), X-ray diffraction, and EDS analysis and fractography. The average ultimate tensile strength (UTS) of 273.2 MPa is attained on the solution treated A380, which is 50% improvement over the vacuum as-cast one. Solution treatment of 480°C x 12hrs increases the average percent of elongation to 3.91% from 1.11% at the as-cast condition. (Abstract shortened by UMI.)Dept. of Electrical and Computer Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2004 .W375. Source: Masters Abstracts International, Volume: 43-01, page: 0298. Adviser: Henry Hu. Thesis (M.A.Sc.)--University of Windsor (Canada), 2004

ReFit: Recurrent Fitting Network for 3D Human Recovery

We present Recurrent Fitting (ReFit), a neural network architecture for single-image, parametric 3D human reconstruction. ReFit learns a feedback-update loop that mirrors the strategy of solving an inverse problem through optimization. At each iterative step, it reprojects keypoints from the human model to feature maps to query feedback, and uses a recurrent-based updater to adjust the model to fit the image better. Because ReFit encodes strong knowledge of the inverse problem, it is faster to train than previous regression models. At the same time, ReFit improves state-of-the-art performance on standard benchmarks. Moreover, ReFit applies to other optimization settings, such as multi-view fitting and single-view shape fitting. Project website: https://yufu-wang.github.io/refit_humans/Comment: ICCV 202

Analysis on Random Fuzzy Queueing Systems with Finite Capacity

This paper discusses random fuzzy queueing systems with finite capacity, where the interarrival times and service times are characterized as random fuzzy variables. Fuzzy simulation techniques are designed to estimate the membership degree, the expected value of system length, and the credibility measure that the system length does not exceed a predetermined level. Furthermore, the rough figures of the membership function and credibility distribution function of the system length can be obtained. Finally, an example is given to illustrate the effectiveness of the presented techniques