Image composition schemes for sort-last polygon rendering on 2Dmesh multicomputers

In a sort-last polygon rendering system, the efficiency of image composition is very important for achieving fast rendering. In this paper, the implementation of a sort-last rendering system on a general purpose multicomputer system is described. A two-phase sort-last-full image composition scheme is described first, and then many variants of it are presented for 2D mesh message-passing multicomputers, such as the Intel Delta and Paragon. All the proposed schemes are analyzed and experimentally evaluated on Caltech's Intel Delta machine for our sort-last parallel polygon renderer. Experimental results show that sort-last-sparse strategies are better suited than sort-last-full schemes for software implementation on a general purpose multicomputer system. Further, interleaved composition regions perform better than coherent regions. In a large multicomputer system. Performance can be improved by carefully scheduling the tasks of rendering and communication. Using 512 processors to render our test scenes, the peak rendering rate achieved on a 282,144 triangle dataset is dose to 4.6 million triangles per second which is comparable to the speed of current state-of-the-art graphics workstations     

On Methods to Align and Access Data Arrays in Parallel Computers

We present methods to store and access templates of data arrays in parallel processors with shuffle-exchange-type interconnection networks. For this purpose, we define the class of composite linear permutations. In our method, each element of the data array is stored in the memory module determined by applying a suitable composite linear permutation on its indices. Simple necessary and sufficient criteria to avoid memory conflicts in the access of important templates such as row, column, main diagonal, and square block are given based on the composite linear permutation involved. The criteria so derived also specify the set of permutations to be realized by an interconnection network to avoid network conflicts. In particular, we give the criteria to be satisfied by a scheme of the proposed class to avoid network conflicts during the access of templates, when shuffle-exchange-type networks are used. Almost all the previously known scrambled storage methods are special cases in the class of storage methods presented in this paper.     

Correlation of compaction pressure, green density, pore size distribution and sintering temperature of a nano-crystalline 2Y-TZP-Al2O3 composite

Highly sinter-active nano crystalline composite powder of 2 mol% yttria doped tetragonal zirconia polycrystal (2Y-TZP) with 2 wt% alumina was synthesized by co-precipitation method. Crystallization temperature of the amorphous precursor powder, measured from simultaneous thermogravimetric (TG) and differential thermal analysis (DTA) techniques was found to be ∼470 °C. The powder was calcined at different temperatures in the range of 700-1000 °C. XRD patterns of the calcined powders revealed the presence of a single tetragonal phase. Particle size of the calcined powder measured by different techniques (X-ray line broadening, BET surface area and laser scattering technique) indicated an increase in the average particle size with calcination temperature. The study of compaction behaviour revealed the presence of soft agglomerates in the calcined powder. Pore size distribution of the green compacts obtained from a mercury porosimeter was found to be monomodal above a critical pressure. The onset temperature of sintering was found to increase with calcination temperature. Powders calcined at 800 °C and 900 °C had shown better sinterability at 1200 °C owing to the presence of finer pores with a narrow size distribution in the green compacts. Sintering behaviour of the powder calcined at 700 °C was found to be marginally poorer in comparison to the other samples, whereas the powder calcined at 800 °C had demonstrated best densification behaviour, especially when compacted at 300 MPa.     

Formulation and in vitro evaluation of transdermal delivery of zidovudine—An anti‐HIV drug

This study was designed to develop matrix type of transdermal‐controlled delivery system for zidovudine using Eudragit L100 by varying the amounts of drug in addition to polyethylene glycol as a plasticizer and Tween 80® as a penetration enhancer. Transparent smooth and flexible films were characterized for weight, thickness uniformity, and drug content. Drug interactions with the polymer films were studied by differential scanning calorimetry, whereas X‐ray diffraction was used to understand the drug polymorphism in the films. The in vitro drug release experiments were performed in phosphate buffer using the Keshary‐Chien diffusion cell. Variations of drug release profiles were analyzed using the Ritger and Peppas empirical equation to describe the type of release mechanism. The exponent n values of the equation varied over the wide range of 0.75–2.23, suggesting non‐Fickian to super Case‐II type of diffusion transport. Statistical analyses of release data performed by the analysis of variance (ANOVA) method indicated significant differences within experimental measurements. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Communication and computation optimization of concurrent kernels using kernel coalesce on a GPU

General purpose computation on graphics processing unit (GPU) is rapidly entering into various scientific and engineering fields. Many applications are being ported onto GPUs for better performance. Various optimizations, frameworks, and tools are being developed for effective programming of GPU. As part of communication and computation optimizations for GPUs, this paper proposes and implements an optimization method called as kernel coalesce that further enhances GPU performance and also optimizes CPU to GPU communication time. With kernel coalesce methods, proposed in this paper, the kernel launch overheads are reduced by coalescing the concurrent kernels and data transfers are reduced incase of intermediate data generated and used among kernels. Computation optimization on a device (GPU) is performed by optimizing the number of blocks and threads launched by tuning it to the architecture. Block level kernel coalesce method resulted in prominent performance improvement on a device without the support for concurrent kernels. Thread level kernel coalesce method is better than block level kernel coalesce method when the design of a grid structure (i.e., number of blocks and threads) is not optimal to the device architecture that leads to underutilization of the device resources. Both the methods perform similar when the number of threads per block is approximately the same in different kernels, and the total number of threads across blocks fills the streaming multiprocessor (SM) capacity of the device. Thread multi‐clock cycle coalesce method can be chosen if the programmer wants to coalesce more than two concurrent kernels that together or individually exceed the thread capacity of the device. If the kernels have light weight thread computations, multi clock cycle kernel coalesce method gives better performance than thread and block level kernel coalesce methods. If the kernels to be coalesced are a combination of compute intensive and memory intensive kernels, warp interleaving gives higher device occupancy and improves the performance. Multi clock cycle kernel coalesce method for micro‐benchmark1 considered in this paper resulted in 10–40% and 80–92% improvement compared with separate kernel launch, without and with shared input and intermediate data among the kernels, respectively, on a Fermi architecture device, that is, GTX 470. A nearest neighbor (NN) kernel from Rodinia benchmark is coalesced to itself using thread level kernel coalesce method and warp interleaving giving 131.9% and 152.3% improvement compared with separate kernel launch and 39.5% and 36.8% improvement compared with block level kernel coalesce method, respectively.Copyright © 2013 John Wiley & Sons, Ltd.     

Quantitation of Multiple Sphingolipid Classes Using Normal and Reversed-Phase LC–ESI–MS/MS: Comparative Profiling of Two Cell Lines

Sphingolipids are an important class of compounds that regulate signal transduction and other vital cellular processes. Herein, we report sensitive normal and reversed phase LC–MS/MS methods for quantitation of multiple sphingolipid classes. In the normal-phase ESI/MS/MS method, a high content of organic solvents was utilized, which, although it included hexane, ethyl acetate, acetonitrile containing 2% methanol, 1–2% acetic acid, and 5 mM ammonium acetate, resulted in a very efficient electrospray ionization of the ceramides (Cers) and hexosylceramides (MHCers). Three normal-phase LC–MS/MS methods using segmented phases were developed to specifically target Cers, MHCers, or sphingomyelins (SMs). This segmentation scheme increases the number of data points acquired for a given analyte and enhances the sensitivity and specificity of the measurements. Nine separate reversed phase chromatography methods were developed for the three classes of compounds. These assays were used for comparing the levels of Cers, SMs, and MHCers from mouse embryonic fibroblast (pMEF) and human embryonic kidney (HEK293) cells. These findings were then compared with the reported data from RAW264.7 mouse macrophage cells, BHK21 hamster cells, and human plasma and serum samples. The analysis of cell lines, using both normal and reversed phase chromatography, revealed discrimination based on the type of chromatography chosen, while sphingolipid assays of samples containing different amounts of protein showed different results, even after normalizing for protein content. Also, LC/MS/MS profiles were provided for the classes and individual compounds so that they could be used as “molecular profiles” for class or individual sample analysis.     

A fault‐tolerant modular multilevel inverter topology

Multilevel inverter topologies have received an increasing importance for their modular structures with better integration of renewable energy sources and reduced filtering requirements. But reliability is compromised in the process of decreasing the number of switches to produce the maximum number of voltage levels. This paper elevates a single‐phase fault‐tolerant inverter topology, which is modular in structure. The proposed inverter is analyzed for open‐ or short‐circuit faults in sources and open‐circuit faults in switches. Sine Pulse Width Modulation with multicarriers technique is used to control the circuit. The carrier signals are reconfigured under fault conditions based on levels to be generated by bypassing the faulted switch or source. The circuit is simulated in MATLAB/SIMULINK, and experimental setup is developed to claim the fault tolerance of proposed inverter.     

Thermal bonding of polypropylene films and fibers

The thermal bonding behavior of different grades of polypropylene was studied in this research. Initial bonding studies were done with polypropylene films of different grades of polymer with varying morphology, and the studies were extended to polypropylene fibers. Polypropylene fibers manufactured with different cross‐sections, deniers, polymer melt‐flow rates, and different processing conditions were bonded under various conditions. The effect of film structure, properties, and bonding conditions on the bonding efficiency was studied by comparing the tensile strength of bonded films. Thermal bonding was carried for a range of temperatures covering poor, optimum, and over bonding. Changes taking place to the polymer in bond point and the original surface were analyzed using the SEM. Higher bond strength was observed in the vicinity of melting temperature and the strength reduced with a further increase in bonding temperature. The frequent failure point was observed at the bond edge crossover points where film undergoes maximum thickness transition. Lower pressure and shorter time were found to be appropriate for bonding. Films with lower orientation formed better bonds. The optimum bond strength and the optimum bonding temperature observed were different for different polymers. Fiber bond strength results were similar to the results observed in the case of films with respect to the bonding temperatures studied. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of replacement of castor oil and polychloroprene by chlorinated paraffin in butyl compounds of tyre‐curing bladder

Ways are explored to increase the life and to reduce the cost of tyre‐curing bladders by improving their mechanical and ageing properties. Nine formulations have been designed which involve the partial replacement of polychloroprene (PC) and castor oil (CO), both individually and simultaneously, by chlorinated paraffin (CP) in the butyl bladder compound. The compounds have been tested for various cure properties such as initial torque, minimum torque, scorch time, optimum cure time, cure rate, maximum torque and reversion time. The vulcanized samples have been tested for mechanical properties such as tensile stress at 300 % elongation, tensile strength at break, ultimate elongation, rubber deterioration by dynamic fatigue test and Shore‐A hardness before and after ageing. The results show that tensile strength at break and ultimate elongation decrease, while tensile stress at 300 % elongation increase except in one case (when PC was partially replaced by CP). Simultaneous and individual replacement of CO by CP results in a decrease in hardness of up to 3 phr (base recipe CO 5 phr), whereas further replacement of CO by CP results in an increase in hardness. Tensile stress at 300 % elongation and Shore‐A hardness increase up to a limit while tensile strength at break and ultimate elongation decrease with ageing. © 2000 Society of Chemical Industry