The Influence of Resonance Helical Field on the Z eff and Impurity Radiation in IR-T1 Tokamak

The influence of resonant helical field, RHF, on effective ion charge, Z _eff, and impurity radiations on IR-T1 tokamak discharges was studied. The theoretical calculation of Z _eff with RHF indicated that the Z _eff decreased. To observe the effects of reduced Z _eff on impurity radiation, two important parts of plasma were investigated, equilibrium region of plasma and disruptive plasma. The results obtained from previous experiments on equilibrium plasma showed the increased radiation of impurities, in comparison with preceding and next regions, whereas the new results indicate that the impurities radiation decreases remarkably in disruptive part of plasma.     

The arcless method of testing high-voltage oil-filled equipment for explosion safety

The present paper reports the results of experimental investigations of an arc discharge in the transformer oil under typical conditions of discharge occurring after internal fault in high-voltage oil-filled electric equipment. The flow of the transformer oil under the action of the jet of powder gases has been investigated. It has been shown that the actions of the arc discharge and the jet of powder gases are equivalent provided that energy and the time of action are the same. A new method of explosion safety tests is described in which the dynamic impact of the arc on high-voltage equipment is simulated by means of the dynamic energy stored in explosives. The suitability of the method has been demonstrated on trials of instrument transformers of the 110 kV and 330 kV class.     

Rapid Access Protocols for Discontinuous Transmission in DS-CDMA Systems

In this paper, three reverse link access protocols (AP) enabling discontinuous transmission (DTX) in DS-CDMA personal communication systems are introduced and discussed. The first protocol is synchronous (SDTX-AP), and it uses a so-called synchronous reservation channel to accommodate access requests in a time slotted frame structure. The second uses an asynchronous approach (ADTX-AP) with a spread slotted ALOHA protocol for access requests; access request messages consist of a synchronizing preamble and a user identifier appendix. The third one employs a synchronous structure of overlapping slots, offset in time by a minimum interval (mini-slot) necessary to enable resolution of overlapping access probes sent by different mobile users (MSDTX-AP). Instead of using different spreading codes for different mobile transmitters, all transmitters are assigned the same spreading code to send their access request messages on the access reservation channel. Analysis considers the mean access delay and throughput of the protocols in a multipath fading channel. Numerical results indicate that at high values of offered traffic of access requests mean access delays of ADTX-AP and SDTX-AP are comparable. The mean access delay for the MSDTX-AP depends on the number of minislots or users within each frame, but its throughput is much higher than that of either SDTX-AP or ADTX-AP.     

A discontinuous Galerkin method with block cyclic reduction solver for simulating compressible flows on GPUs

An optimized implementation of a block tridiagonal solver based on the block cyclic reduction (BCR) algorithm is introduced and its portability to graphics processing units (GPUs) is explored. The computations are performed on the NVIDIA GTX480 GPU. The results are compared with those obtained on a single core of Intel Core i7-920 (2.67 GHz) in terms of calculation runtime. The BCR linear solver achieves the maximum speedup of 5.84x with block size of 32 over the CPU Thomas algorithm in double precision. The proposed BCR solver is applied to discontinuous Galerkin (DG) simulations on structured grids via alternating direction implicit (ADI) scheme. The GPU performance of the entire computational fluid dynamics (CFD) code is studied for different compressible inviscid flow test cases. For a general mesh with quadrilateral elements, the ADI-DG solver achieves the maximum total speedup of 7.45x for the piecewise quadratic solution over the CPU platform in double precision.     

Modelling Scenarios to Estimate the Potential Impact of Hydrological Standards on Nutrient Retention in the Tobacco Creek Watershed,Manitoba, Canada

Nutrient loading from agricultural drainage systems into downstream aquatic ecosystems, like Lake Winnipeg in the prairie province of Manitoba, Canada, represents a major challenge for water quality management. In order to improve water quality in downstream waterbodies, the Manitoba government is currently investigating the relationship between hydrological standard of agricultural drainage network and nutrient retention in the drainage systems. Briefly, oversized drains have more capacity to transport nutrients, which can increase nutrient loading to downstream waterbodies, especially during rainfall events. Currently, the hydrological standards of agricultural drainage design in Manitoba were mainly developed according to cost-benefit analysis without considering nutrient retention. The purpose of this study was to use computer modelling techniques to simulate the impact of drain size (based on different hydrological standards) on nutrient retention within an agricultural drainage network. The site chosen was the Tobacco Creek Watershed, an agricultural area which drains into the Red River, and thence into Lake Winnipeg. Suspended sediment, nutrient and flow data, from several locations along the Brown drain within this watershed, were used to calibrate a water quality model. Scenarios were then simulated with the model to estimate how different drain sizes affect nutrient transport and retention. Sampling took place during the spring and summer of 2013 starting with freshet and ending when the drains dried up near mid-summer. Study results indicated that the amount of nutrients transported was generally greater during freshet and summer rain storms. Occasionally, however, nutrients in summer discharge exceeded those transported during freshet. The water quality model was applied to the Brown drain to investigate the effects of different drain sizes for rainfall amounts under 2, 5, 10, 15, and 20 year return periods. Generally the results indicate that as the return periods became larger (in larger channels) lower nutrients concentrations were predicted downstream (higher decay rates). On average, the model predicted a 15%–20% decline in nutrient concentration with a 20-year return channel design compared to a 2-year return. The research from this study may provide an impetus to the policy-making process of drainage design.     

Demosaicing using optimal recovery.

Color images in single-chip digital cameras are obtained by interpolating mosaiced color samples. These samples are encoded in a single-chip charge-coupled device by sampling the light after it passes through a color filter array (CFA) that contains different color filters (i.e., red, green, and blue) placed in some pattern. The resulting sparsely sampled images of the three-color planes are interpolated to obtain the complete color image. Interpolation usually introduces color artifacts due to the phase-shifted, aliased signals introduced by the sparse sampling of the CFAs. This paper introduces a nonlinear interpolation scheme based on edge information that produces high-quality visual results. The new method is especially good at reconstructing the image around edges, a place where the visual human system is most sensitive.     

Electron Barrier Formation at the Organic‐Back Contact Interface is the First Step in Thermal Degradation of Polymer Solar Cells

Long‐term stability of polymer solar cells is determined by many factors, one of which is thermal stability. Although many thermal stability studies occur far beyond the operating temperature of a solar cell which is almost always less than 65 °C, thermal degradation is studied at temperatures that the solar cell would encounter in real‐world operating conditions. At these temperatures, movement of the polymer and fullerenes, along with adhesion of the polymer to the back contact, creates a barrier for electron extraction. The polymer barrier can be removed and the performance can be restored by peeling off the electrode and depositing a new one. X‐ray photoelectron spectroscopy measurements reveal a larger amount of polymer adhered to electrodes peeled from aged devices than electrodes peeled from fresh devices. The degradation caused by hole‐transporting polymer adhering to the electrode can be suppressed by using an inverted device where instead of electrons, holes are extracted at the back metal electrode. The problem can be ultimately eliminated by choosing a polymer with a high glass transition temperature.     

Oxidative dehydrogenation of propane over vanadium catalyst supported on nano-HZSM-5

Vanadium catalyst supported on nano-HZSM-5 was utilized in oxidative dehydrogenation of propane to propylene. The physicochemical properties of the elaborated catalysts were investigated by means of XRD, SEM, FTIR spectra, UV-vis, Raman, NH₃-TPD and H₂-TPR techniques. The effect of vanadium loading (2–10 wt %), temperature (500–600°C) and oxygen to propane ratio (0.5–1.5) on conversion, propylene and ethylene selectivity was studied using full factorial design of experiments. The obtained data were statistically analyzed using the Analysis of Variance (ANOVA) and a p < 0.05 was considered statistically significant. The mathematical relationship of conversion, propylene and ethylene selectivity on three independent variables approximated by a second-order quadratic model. Two-dimensional contour plots were drawn to investigate the effect of independent variables and their interaction on the chosen responses. The function of temperature, oxygen to propane ratio and vanadium content such as acidity and reducibility on the performance of supported vanadium catalysts were discussed.     

Selection of a suitable strain from recombinant Escherichia coli strains with the same genetic structure expressing periplasmic hGM-CSF

The selection of a suitable strain among five recombinant Escherichia coli strains with the same genetic structure that expresses the human granulocyte macrophage colony stimulating factor (hGM-CSF) was carried out based on four criteria:growth rate, expression level, plasmid stability and feasibility for protein extraction. There was no significant difference in growth between the five strains, while a suitable expression level, a high plasmid stability and a good feasibility for protein extraction from periplasmic space were observed for one of the recombinant strains. This strain expressed 27% hGM-CSF relative to total proteins and had 96% plasmid stability after 7-d subcultures on an antibiotic-free LB medium.     

Robust multi-objective optimization for water distribution system design using a meta-metaheuristic

The design of an urban water distribution system (WDS) is a challenging problem involving multiple objectives. The goal of robust multi-objective optimization for WDS design is to find the set of solutions which embodies an acceptable trade-off between system cost and reliability, so that the ideal solution may be selected for a given budget. In addition to satisfying consumer needs, a system must be built to accommodate multiple demand loading conditions, withstand component failures and allow surplus capacity for growth. In a developmental setting, WDS robustness becomes even more crucial, owing to the limited availability of resources, especially for maintenance. Recent optimization studies have achieved success using multi-objective evolutionary algorithms, such as the Non-dominated Sorting Genetic Algorithm II (NSGA-II). However, the multi-objective design of a large WDS within a reasonable timeframe remains a formidable problem, owing to the extremely high computational complexity of the problem. In this paper, a meta-algorithm called AMALGAM is applied for the first time to WDS design. AMALGAM uses multiple metaheuristics simultaneously in an attempt to improve optimization performance. Additionally, a Jumping-gene Genetic Algorithm (NSGA-II-JG) is also applied for the first time to WDS design. These two algorithms were tested against some other metaheuristics (including NSGA-II and a new greedy algorithm) with respect to a number of benchmark systems documented in the literature, and AMALGAM demonstrated the best performance overall, while NSGA-II-JG fared worse than the ordinary NSGA-II. Large cost savings and reliability improvements are demonstrated for a real WDS developmental case study in South Africa.