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Abstract This research attempted to analyze a triple-tube heat exchanger (TTHE) fitted with innovative crimped-spiral ribs to enhance thermal efficiency. The crimped-spiral rib was placed on the top of the internal tube, and the water–alumina nanofluid was employed as the hot fluid within the ribbed side, whereas the two other fluids were pure water. The numerical solutions were performed through the two-phase mixture method, while the turbulent flow was modeled via the Reynolds Stress Model (RSM). The overall heat transfer coefficient (U), heat transfer rate, effectiveness, and performance index enhanced remarkably by using the nanofluid. The greatest increment in the U and effectiveness reached around 44.91 and 41 %, respectively, by the increment of the volume fraction by 0.02. The crimp intensity had an appreciable contribution to the thermal performance. The main mechanism was stronger swirl flow generated by the crimped-spiral rib that yielded boundary layer destruction. The heat transfer capability was increased via the rib pitch decrement and rib height increment. The performance index showed great values even at low volume fractions, which manifested the great merit of the implemented refinements. The thermal attributes were investigated at the first of the result section and then, the hydraulic characteristics were researched.

Abstract Concerns about power quality (PQ) in distribution networks have necessitated the use of PQ measuring/monitoring equipment to detect and analyse PQ problems. As the installation of such equipment at all locations is not economically feasible, minimum number and optimum locations of PQ monitors have been sought in recent researches to meet both economical efficiency and monitoring capability. Focusing on voltage sags, this paper attempts to further reduce the number of PQ monitors obtained by optimum allocation approaches while keeping the desired monitoring capability. Growing number of electric equipment with high sensitivity to voltage sags have raised more concerns about financial losses associated with voltage sags in comparison to other PQ problems. Here, a neural estimator placed at a monitored location is proposed to estimate instantaneous voltage-sag waveforms of a non-monitored sensitive load using local measurements. Echo state network (ESN) is used as the voltage-sag waveform estimator (VSWE). Because of increasing penetration of distributed generations (DGs) and their impacts on voltage-sag performance, they are considered to challenge the estimation task. The proposed ESN-based VSWE is examined on the IEEE 37-bus network. Tests for extensive unseen cases with different fault resistances, fault inception-angles, fault locations and fault types under different load demands and network conditions show acceptable high accuracy of estimations during fault and fault clearing sequences. Furthermore, the performance of the VSWE is investigated during transients due to switching capacitors, DGs, loads and lines.

AbstractCumulus‐intact and ‐denuded unfertilized oocytes from two mouse strains were exposed to 1.5 m ethanol (EtOH) or two cryoproteclant solutions, 1.5 M propanediol (PROH) or 1.5 M dimethylsulfoxide (DMSO), for 4.5 min at 27°C, and the proportion of activating or degenerating oocytes studied. Exposure to DMSO did not significantly increase activation above that of oocytes not exposed to DMSO. Treatment of oocytes in PROH resulted in the activation of up to 87% of viable oocytes. This was significantly higher (P <01) than in control oocytes and comparable to the rate of activation after treatment with EtOH (59–96% activation). In solutions at 1°C, 47% of control oocytes were activated, which was not significantly different from the rate of activation in EtOH (36%) or PROH (50%) at 1°C. Following treatment with PROH, up to 87% of oocytes degenerated within a period of 6 h in vitro. The age of the oocytes (h post hCG) and the time of cumulus removal with the enzyme hyaluronidase, relative to the time of exposure to the chemicals, influenced the level of degeneration in most groups. Significantly fewer oocytes degenerated when cumulus cells were removed before treatment (0–31%) than when the cumulus was left intact throughout the treatment and 6 h culture period (10–87%). Exposure to PROH at 1°C reduced oocyte degeneration to 5%. We conclude that PROH causes significantly greater losses of oocytes as a result of parthenogenetic activation and degeneration than of exposure to DMSO.

Abstract Gas cyclone separators have been widely used in different industries. In this study, to find the best geometrical ratios of Stairmand cyclone separator, computational fluid dynamics (CFD), design of experiments (DOE), multi-gene genetic programming (MGGP), and ten meta-heuristic algorithms were combined. Six geometrical dimensions of the gas cyclone separator including inlet height and width, vortex finder length and its diameter, cylinder height and cone-tip diameter were optimized. The obtained models from MGGP were optimized by ten meta-heuristic algorithms and non-dominated Pareto fronts were analyzed using six unary and binary metrics and PROMETHEE II as a decision making method. According to the optimization results, multi-objective Particle Swarm Optimization (MOPSO) showed the best performance and generated more preferred designs than Stairmand design compared to other algorithms. These preferred designs increased the collection efficiency within 0.36 to 6% and decreased the pressure drop within 3.3 to 27.5% compared to the Stairmand.

Among various bioreactors examined in anaerobic digestion and dark fermentation, UASB bioreactor has shown to be a promising alternative. However, mass transfer resistance and biomass washout have been the issues that reported as draw backs of the granular system in the literature. Another problem associated with such a system is its long start-up period as a result of biomass washout and long microbial granulation stage. In this paper, the results obtained from an UASFF bioreactor in methane (AD process) and hydrogen (DF process) production from POME, are presented to assess mass transfer of substrate into the granules and also study the role of internal packing used in the middle part of reactor in the process stability. The value of effectiveness factor, η, for AD and DF processes were calculated to be 0.96 and 0.94, respectively, indicating that there was no mass transfer resistance due to internal and/or external factors. The results showed that the packing material could retain biomass in the reactor and had outstanding contribution in the granulation enhancement. Its role as a supplementing treatment stage was more significant at low HRTs and up-flow velocities.

Short-term generation scheduling is an important function in daily operational planning of power systems. It is defined as optimal scheduling of power generators over a scheduling period while respecting various generator constraints and system constraints. Objective of the problem includes costs associated with energy production, start-up cost and shut-down cost along with profits. The resulting problem is a large scale nonlinear mixed-integer optimization problem for which there is no exact solution technique available. The solution to the problem can be obtained only by complete enumeration, often at the cost of a prohibitively computation time requirement for realistic power systems. This paper presents a hybrid algorithm which combines Lagrangian Relaxation (LR) together with Evolutionary Algorithm (EA) to solve the problem in cooperative and competitive energy environments. Simulation studies were carried out on different systems containing various numbers of units. The outcomes from different algorithms are compared with that from the proposed hybrid algorithm and the advantages of the proposed algorithm are briefly discussed.

AbstractIf the energy‐density of prey bodies is not uniform, predators usually should maximize their rate of energy intake while foraging by selectively consuming energy‐rich regions of their prey and discarding other parts. In this study, the hypothesis of selective body‐part consumption was tested using two species of dasyurid marsupials, Sminthopsis youngsoni and Ningaui ridei, and their invertebrate prey in arid central Australia. Energy‐densities were similar for several divergent types of prey, including whole insects, centipedes, and spiders (20.2 ± 2.19 (sd) J/mg ash‐free dry mass), but there were marked differences in energy‐density among orders of insects and also between different body regions of invertebrates. In captivity, the two dasyurid species consumed different body regions of prey in the same way. For beetles and cockroaches, the rank order for selection of body parts was abdomen, thorax, head, then legs; for centipedes it was body, then head + legs; and for spiders it was opisthosoma, prosoma and then legs. Selection of prey body regions by the marsupials correlated closely with the energy‐densities of these regions, and also with the rates of energy intake that they yielded. In the field, selection of body parts of arthropod prey by dasyurids probably occurs primarily when prey is abundant. This selection should allow maximization of rates of energy intake in favourable periods and should, in turn, allow dasyurid predators to effectively exploit pulses of prey resources in the temporally variable desert environment.

This paper presents a novel modified interactive honey bee mating optimization (IHBMO) base fuzzy stochastic long-term approach for determining optimum location and size of distributed energy resources (DERs). The Monte Carlo simulation method is used to model the uncertainties associated with long-term load forecasting. A proper combination of several objectives is considered in the objective function. Reduction of loss and power purchased from the electricity market, loss reduction in peak load level and reduction in voltage deviation are considered simultaneously as the objective functions. First, these objectives are fuzzified and designed to be comparable with each other. Then, they are introduced into an IHBMO algorithm in order to obtain the solution which maximizes the value of integrated objective function. The output power of DERs is scheduled for each load level. An enhanced economic model is also proposed to justify investment on DER. An IEEE 30-bus radial distribution test system is used to illustrate the effectiveness of the proposed method.