Operating system support for a video-on-demand file service

This paper describes the design and implementation of a continuous media file server intended for use in emerging video-on-demand applications. The main focus and contribution of the paper is in scheduling and admission-control algorithms for accessing the server's processor and storage resources. The scheduling algorithms support multiple classes of tasks with diverse performance requirements and allow for the co-existence of guaranteed real-time requests with sporadic, and unsolicited requests. The scheduler maintains performance guarantees for real-time streams in the presence of unpredictably varying non-real-time traffic while ensuring system stability even during overloads. A prototype video file server was implemented on an Intel 486 platform. Performance results show that a large number of streams can be supported, while maintaining efficient utilization of system resources.     

A 64-b microprocessor with multimedia support

A 167 MHz 64 b VLSI CPU chip is described. The chip executes a 333-MFLOPS (peak) with an estimated system performance of 270SPECint92/380SPECfp92 (@167 MHz, 2 MB E-cache). The 17.7×17.8 mm die is fabricated with a 0.5 micron CMOS technology with four metal layers and contains 5.2 M transistors. The superscalar processor is capable of sustaining an execution rate of four instructions per cycle even in the presence of conditional branches and cache misses. Four fully pipelined 8×16 b multipliers and four single-cycle latency 16 b adders combine to speed up image processing, 2-D, 3-D graphics, video compression/decompression by up to an order of magnitude. High clock speed was obtained by the use of delayed reset logic, a new register file design; and novel comparators. Strict design methodology allowed fully functional first silicon which met all speed targets. The power dissipation of the chip is 28 W     

The conduction system in simple, regular (D-), complete transposition with ventricular septal defect

Utilizing an indirect Coombs' technique, humoral antibodies to marihuana and its major components were found in 34 subjects with known marihuana exposure. Similar antibodies were absent in the sera of a control population of 34 subjects with no known marihuana exposure. The specificity of the antibodies was confirmed by differential absorption studies in six seropositive subjects. Routine laboratory tests were abnormal in 22 of 34 seropositive subjects and in 9 of 34 control subjects. The relationship of seropositivity to abnormal laboratory tests is not certain.     

Application of vanishing variable methods to special structured transportation problems

Methods of determining vanishing variables in transportation problems have appeared in a literature published by Intrator and Lev [4]. This paper implements the theorems to special structured transportation problems in general, and tridiagonal transportation problems in particular. New rules are developed for reducing the amount of computations required for solving tridiagonal transportation problems. The rules will result in assigning optimal values to the variables (the values are often zero) and even decomposition of large problems into smaller sub problems.     

A dynamic-sized nonblocking work stealing deque

The non-blocking work-stealing algorithm of Arora, Blumofe, and Plaxton (hencheforth ABP work-stealing) is on its way to becoming the multiprocessor load balancing technology of choice in both industry and academia. This highly efficient scheme is based on a collection of array-based double-ended queues (deques) with low cost synchronization among local and stealing processes. Unfortunately, the algorithm's synchronization protocol is strongly based on the use of fixed size arrays, which are prone to overflows, especially in the multiprogrammed environments for which they are designed. This is a significant drawback since, apart from memory inefficiency, it means that the size of the deque must be tailored to accommodate the effects of the hard-to-predict level of multiprogramming, and the implementation must include an expensive and application-specific overflow mechanism. This paper presents the first dynamic memory work-stealing algorithm. It is based on a novel way of building non-blocking dynamic-sized work stealing deques by detecting synchronization conflicts based on “pointer-crossing” rather than “gaps between indexes” as in the original ABP algorithm. As we show, the new algorithm dramatically increases robustness and memory efficiency, while causing applications no observable performance penalty. We therefore believe it can replace array-based ABP work stealing deques, eliminating the need for application-specific overflow mechanisms. This work was conducted while Yossi Lev was a student at Tel Aviv University, and is derived from his MS thesis [1].     

A novel method for controlling LNG pool fires

A novel method for controlling LNG pool fires has been developed. In the proposed method, a layer of granules or blocks of nonflammable, low-density, solid material is situated in bund areas surrounding liquid fuel storage tanks. In the event of a major spill, this material will float on the liquid and by shielding the surface from back radiation, will cause a reduction in the size of the fire if the pool is accidentally ignited.     

Effect of photocatalytic and hydrophobic coatings on brewery surface microorganisms

The aim of this study was to determine whether process hygiene in the beverage industry could be improved by applying new coating techniques to process surfaces. Photocatalytic titanium dioxide (TiO(2)) and hydrophobic coatings applied to stainless steel with or without added antimicrobial compounds were studied in laboratory attachment tests and in a 15-month process study. No clear reductions in numbers of attached microbes were obtained with photocatalytic coatings, except for coatings to which silver had been added. These TiO(2)+Ag coatings reduced microbial coverage in laboratory studies and in some process samples. Hydrophobic coatings reduced the area coverage of microorganisms in 4-h laboratory studies but did not affect colony counts in laboratory or process studies. The surfaces had changed from hydrophobic into hydrophilic during the process study. The coatings did not mechanically fully withstand process conditions; part of the hydrophobic coatings had peeled off, most of the precipitated Ag had dissolved, and some of the TiO(2) coatings were damaged. In conclusion, functional coatings have potential for reducing microbial loads on beverage industry surfaces, but these coatings need further development.     

Electrospun polyurethane fibers for absorption of volatile organic compounds from air

Electrospun polyurethane fibers for removal of volatile organic compounds (VOC) from air with rapid VOC absorption and desorption have been developed. Polyurethanes based on 4,4-methylenebis(phenylisocyanate) (MDI) and aliphatic isophorone diisocyanate as the hard segments and butanediol and tetramethylene glycol as the soft segments were electrospun from their solutions in N,N-dimethylformamide to form micrometer-sized fibers. Although activated carbon possessed a many-fold higher surface area than the polyurethane fiber meshes, the sorption capacity of the polyurethane fibers was found to be similar to that of activated carbon specifically designed for vapor adsorption. Furthermore, in contrast to VOC sorption on activated carbon, where complete regeneration of the adsorbent was not possible, the polyurethane fibers demonstrated a completely reversible absorption and desorption, with desorption obtained by a simple purging with nitrogen at room temperature. The fibers possessed a high affinity toward toluene and chloroform, but aliphatic hexane lacked the necessary strong attractive interactions with the polyurethane chains and therefore was less strongly absorbed. The selectivity of the polyurethane fibers toward different vapors, along with the ease of regeneration, makes them attractive materials for VOC filtration.     

Aldehyde-alcohol reactions catalyzed under mild conditions by chromium(III) terephthalate metal organic framework (MIL-101) and phosphotungstic acid composites

Porous materials based on chromium(III) terephthalate metal organic frameworks (MIL-101) and their composites with phosphotungstic acid (PTA) were studied as heterogeneous acid catalysts in aldehyde-alcohol reactions exemplified by acetaldehyde-phenol (A-P) condensation and dimethylacetal formation from benzaldehyde and methanol (B-M reaction). The MIL-101 was synthesized solvothermically in water, and the MIL101/PTA composite materials were obtained by either impregnation of the already prepared MIL-101 porous matrix with phosphotungstic acid solution or by solvothermic treatment of aqueous mixtures of Cr(NO(3))(3), and terephthalic and phosphotungstic acids. The MIL101/PTA materials appeared to be effective catalysts for both A-P and B-M reactions occurring at room temperature, with half-lives ranging from 0.5 h (A-P) to 1.5-2 h (B-M) and turnover numbers over 600 for A-P and over 2900 for the B-M reaction, respectively. A synergistic effect of the strong acidic moieties (PTA) addition to mildly acidic Br?nsted and Lewis acid cites of the MIL-101 was observed with the MIL101/PTA composites. The ability of the PTA and MIL101/PTA materials to strongly absorb and condense acetaldehyde vapors was discovered, with the MIL101/PTA absorbing over 10-fold its dry weight of acetaldehyde condensate at room temperature. The acetaldehyde was converted rapidly to crotonaldehyde and higher-molecular-weight compounds while in contact with MIL-101 and MIL101/PTA materials. The stability of the MIL-101 and MIL101/PTA catalysts was assessed within four cycles of the 1-day alcohol-aldehyde reactions in terms of the overall catalyst recovery, PTA or Cr content, and reaction rate constants in each cycle. The loss of the catalyst over 4 cycles was approximately 10 wt % for all tested catalysts due to the incomplete recovery and minute dissolution of the components. The reaction rates in all cycles remained unchanged and the catalyst losses stopped after the third cycle. The developed MIL101/PTA composites appear to be feasible for industrial catalytic applications.