Comparison Of Various Configurations Research Articles

Advances in Membrane Distillation Module Configurations.

Membrane Distillation (MD) is a membrane-based, temperature-driven water reclamation process. While research emphasis has been largely on membrane design, upscaling of MD has prompted advancements in energy-efficient module design and configurations. Apart from the four conventional configurations, researchers have come up with novel MD membrane module designs and configurations to improve thermal efficiency. While membrane design has been the focus of many studies, development of appropriate system configurations for optimal energy efficiency for each application has received considerable attention, and is a critical aspect in advancing MD configurations. This review assesses advancements in modified and novel MD configurations design with emphasis on the effects of upscaling and pilot scale studies. Improved MD configurations discussed in this review are the material gap MD, conductive gap MD, permeate gap MD, vacuum-enhanced AGMD/DCMD, submerged MD, flashed-feed MD, dead-end MD, and vacuum-enhanced multi-effect MD. All of these modified MD configurations are designed either to reduce the heat loss by mitigating the temperature polarization or to improve the mass transfer and permeate flux. Vacuum-enhanced MD processes and MD process with non-contact feed solution show promise at the lab-scale and must be further investigated. Hollow fiber membrane-based pilot scale modules have not yet been sufficiently explored. In addition, comparison of various configurations is prevented by a lack of standardized testing conditions. We also reflect on recent pilot scale studies, ongoing hurdles in commercialization, and niche applications of the MD process.

Numerical Prediction of the Seismic Behavior of Reassembled Columns in Ancient Structures: An Anastylosis Model for the Temple of Apollo Pythios in Gortyn (Crete)

The Temple of Apollo Pythios in Gortyn (Crete, Greece) dates back to the mid-7th century BC. The temple underwent several transformations and an ultimate destruction over time that resulted in the current remains of a Roman colonnade composed of six fragmented stone columns lying on the ground within the naos. In addition, the region was struck by several earthquakes which contributed to the various changes. The analysis of the fragments composing the column portions and their geometric features provided a possible outline for their standing repositioning. Based on the current seismic hazard of the region, a predictive numerical model of the colonnade in the anastylosis conditions suggested the need for proper connections between the fragments and the bases to ensure their overall conservation as a compound structure. The comparison of various configurations of intervention and the simple superimposition of the fragments also provided details on the accomplishment of minimal and compatible solutions.

Optimal Scheduling of Hybrid Multi-Carrier System Feeding Electrical/Thermal Load Based on Particle Swarm Algorithm

In this paper, the optimum coordination of an energy hub system, fed with multiple fuel options (natural gas, wood chips biomass, and electricity) to guarantee economically, environmentally friendly, and reliable operation of an energy hub, is presented. The objective is to lessen the total operating expenses and CO2 emissions of the hub system. Additionally, the effect of renewable energy sources as photovoltaics (PVs) and wind turbines (WTs) on energy hub performance is investigated. A comparison of various configurations of the hub system is done. The proper planning of the hub elements is determined by a multi-objective particle swarm optimization (PSO) algorithm to achieve the lowest level of the gross running cost and total system emissions, simultaneously. The outcomes show that the natural gas turbine (NGT) is superior to the biomass generating unit in lowering the gross operating expenses, while using the biomass wood chips plant is most effective in lessening the total CO2 emissions than the NGT plant. Furthermore, the combination of the natural gas turbine, biomass generator, photovoltaics, and wind turbines enhances the operation of the hub infrastructures by lessening both the gross operating cost and overall CO2 emission simultaneously.

Thermo-economic performance comparison of two configurations of combined steam and organic Rankine cycle with steam Rankine cycle driven by Al2O3-therminol VP-1 based PTSC

The main goal of this study is to compare thermo-economic performance of three configurations of power generation system driven by solar heat source in which nanofluid based PTSC is used. Configuration 1 presents simple steam Rankine cycle (SRC) and configuration 2 and 3 show combined SRC with organic Rankine cycle (ORC) in two different conditions. In second configuration, ORC absorbs heat from SRC condenser and in third one, ORC absorbs heat in ORC evaporator from remain heat of SRC evaporator exiting nanofluid. The effects of various parameters such as concentration of nanoparticles, SRC evaporation temperature and SRC condensation temperature are investigated on output parameters and each configuration is optimized by using 4 different organic fluids (R113, n-hexane, cyclohexane, toluene) in ORC. After parametric analysis and performance comparison in base case, components performance and comparison of various configurations are examined at optimal point. Comparison of applying organic fluids in ORC related to configurations 2 and 3 shows that toluene has the best performance. Nanoparticles concentration for all 3 configurations is equal to zero at the selected optimal point and configurations 1 and 2 have relatively similar thermo-economic performance. Configuration 3 has the most net power output (4293 kW); however, it has the weakest thermo-economic performance due to the highest total cost rate (1434 $/h) and less energy and exergy efficiencies.

Comparison of various configurations of the absorption-regeneration process using different solvents for the post-combustion CO2 capture applied to cement plant flue gases

Carbon Capture Utilization or Storage (CCUS) has gained widespread attention as an option for reducing CO2 emissions from power plants but specific developments are still needed for the application to cement plants. More precisely, the post-combustion CO2 capture process by absorption-regeneration is the more mature technology but its cost reduction is still necessary. The present study is focusing on Aspen Hysys™ simulations of different CO2 capture process configurations (namely “Rich Solvent Recycle” (RSR), “Solvent Split Flow” (SSF), “Lean/Rich Vapor Compression” (L/RVC)) applied to the flue gas coming from the Norcem Brevik cement plant (taken as case study) and using three different solvents, namely: monoethanolamine (MEA), piperazine (PZ) and piperazine-methyldiethanolamine (MDEA) blend. For each configuration and solvent, different parametric studies were carried out in order to identify the operating conditions ((L/G)vol., split fraction, flash pressure variation, etc.) minimizing the solvent regeneration energy. Total equivalent thermodynamic works and utilities costs were also analyzed. It was shown that the configurations studied allow regeneration energy savings in the range 4–18%, LVC and RVC leading to the higher ones. As perspectives, other configurations and combination of configurations will be considered in order to further reduce the energy consumption of the process.

Various coupling configurations on the performance of two‐dimensional coupled oscillator arrays

Coupled oscillator arrays (COAs) can be used to control the phase distribution across the aperture of an array antenna in such a manner as to affect steering of the beam without the use of phase shifters. Given the various possible planar configurations of COAs, a systematic design approach is necessary. In this study, the authors present a comprehensive comparison of various configurations of planar COAs based on their sensitivity to random errors in their free running frequencies. The parameters considered are (a) the beam pointing error of the array, (b) the locking probability, (c) the side lobe level, and (d) the beam width of the radiation pattern. These results can serve as a design strategy for choosing optimal configurations of planar COAs based on the needs of each particular application.

The Energy-Water Nexus: An Analysis and Comparison of Various Configurations Integrating Desalination with Renewable Power

This investigation studies desalination powered by wind and solar energy, including a study of a configuration using PVT solar panels. First, a water treatment was developed to estimate the power requirement for brackish groundwater reverse-osmosis (BWRO) desalination. Next, an energy model was designed to (1) size a wind farm based on this power requirement and (2) size a solar farm to preheat water before reverse osmosis treatment. Finally, an integrated model was developed that combines results from the water treatment and energy models. The integrated model optimizes performances of the proposed facility to maximize daily operational profits. Results indicate that integrated facility can reduce grid-purchased electricity costs by 88% during summer months and 89% during winter when compared to a stand-alone desalination plant. Additionally, the model suggests that the integrated configuration can generate $574 during summer and $252 during winter from sales of wind- and solar-generated electricity to supplement revenue from water production. These results indicate that an integrated facility combining desalination, wind power, and solar power can potentially reduce reliance on grid-purchased electricity and advance the use of renewable power.

Segmented bimorph mirrors for adaptive optics: morphing strategy.

This paper discusses the concept of a light weight segmented bimorph mirror for adaptive optics. It focuses on the morphing strategy and addresses the ill-conditioning of the Jacobian of the segments, which are partly outside the optical pupil. Two options are discussed, one based on truncating the singular values and one called damped least squares, which minimizes a combined measure of the sensor error and the voltage vector. A comparison of various configurations of segmented mirrors was conducted; it is shown that segmentation sharply increases the natural frequency of the system with limited deterioration of the image quality.

Solid Oxide Electrolysis Cell Systems — Variant Analysis of the Structures and Parameters

The paper presents a variant analysis of the structure of SOEC systems. The main parameters of such systems are indicated and commented. The comparison of various configurations is shown in terms of efficiency obtained. High efficiency (70%) hydrogen generation seems possible with systems like these.

Variant Analysis of the Structure and Parameters of SOFC Hybrid Systems

The paper presents a variant analysis of the structure of SOFC hybrid system. The systems are divided into two gropus: atmospheric and pressurized. The main parameter of such systems are indicated and commented. The comparison of various configurations is shown in a view of efficiency obtained. The ultra high efficiency (65% HHV, 72% LHV) of electricity production seems to be possible by systems like these.

Optimal design and operation of building services using mixed-integer linear programming techniques

As mandated by several directives issued by the European Union, starting from 2020, new buildings must be designed and constructed as low-energy buildings. This situation is to be achieved mostly by an installation of renewable energy technologies, storage systems, and improved insulations. As a result, the capital cost of these building systems and thus the potential for optimization will grow significantly. In addition, on the electric supply side, a smart grid with time-varying electricity tariffs may be established. These two directions of impact offer the opportunity to optimize the interactions between the so-called smart building and the distribution grid. Due to the stringent requirements for such future building systems, their complexity of design and control will increase inevitably. Therefore, in this paper a design framework for the optimal selection and sizing of a smart building system is presented. Various building services such as thermal and electrical storages, heating and cooling systems, and renewable energy sources are modeled and implemented using mixed-integer linear programming techniques. In order to enable a reasonable comparison of various configurations, optimal operating strategies are computed in parallel. Finally, the impact of regulatory policies and variable pricing systems on the design of the building components are examined.

The NILE Project — Advances in the Conversion of Lignocellulosic Materials into Ethanol

NILE ("New Improvements for Lignocellulosic Ethanol") was an integrated European project (2005-2010) devoted to the conversion of lignocellulosic raw materials to ethanol. The main objectives were to design novel enzymes suitable for the hydrolysis of cellulose to glucose and new yeast strains able to efficiently converting all the sugars present in lignocellulose into ethanol. The project also included testing these new developments in an integrated pilot plant and evaluating the environmental and socio-economic impacts of implementing lignocellulosic ethanol on a large scale. Two model raw materials – spruce and wheat straw – both preconditioned with similar pretreatments, were used. Several approaches were explored to improve the saccharification of these pretreated raw materials such as searching for new efficient enzymes and enzyme engineering. Various genetic engineering methods were applied to obtain stable xylose- and arabinose-fermenting Saccharomyces cerevisiae strains that tolerate the toxic compounds present in lignocellulosic hydrolysates. The pilot plant was able to treat 2 tons of dry matter per day, and hydrolysis and fermentation could be run successively or simultaneously. A global model integrating the supply chain was used to assess the performance of lignocellulosic ethanol from an economical and environmental perspective. It was found that directed evolution of a specific enzyme of the cellulolytic cocktail produced by the industrial fungus, Trichoderma reesei, and modification of the composition of this cocktail led to improvements of the enzymatic hydrolysis of pretreated raw material. These results, however, were difficult to reproduce at a large scale. A substantial increase in the ethanol conversion yield and in specific ethanol productivity was obtained through a combination of metabolic engineering of yeast strains and fermentation process development. Pilot trials confirmed the good behaviour of the yeast strains in industrial conditions as well as the suitability of lignin residues as fuels. The ethanol cost and the greenhouse gas emissions were highly dependent on the supply chain but the best performing supply chains showed environmental and economic benefits. From a global standpoint, the results showed the necessity for an optimal integration of the process to co-develop all the steps of the process and to test the improvements in a flexible pilot plant, thus allowing the comparison of various configurations and their economic and environmental impacts to be determined.

Comparison of various configurations of CDC-type traps for the collection of Phlebotomus papatasi Scopoli in southern Israel

We conducted two experiments to determine the best CDC-trap configuration for catching male and female Phlebotomus papatasi. First, visual features were evaluated. Standard CDC traps were modified to have black or white catch bags, black or white lids, or no lids and these were tried in different combinations. Significantly more male sand flies were caught by darker traps; significantly more females were captured by traps with either all black or a combination of black and white features. Attraction may be due to dark color or contrast in colors. CDC traps with suction and the following features were also evaluated: no light; incandescent light; ultraviolet (UV) light; combination of black color, heat and moisture; CO(2) alone, or a combination of black color, heat, moisture, and CO(2) simultaneously, all in upright and inverted positions, with the opening for insect entry always 50 cm above the ground. Significantly more females than males were caught by all traps (standard and inverted) except the control traps with suction only. Traps with CO(2) caught more sand flies than traps without CO(2.) Traps with black color, heat and moisture captured significantly more sand flies than the control traps, but with the addition of CO(2) , these traps catch significantly more sand flies than the other traps evaluated. Inverting traps increased the catch for like traps by about two times.

MODELING OF TRACE- AND BLOCK-BASED CACHES

Recent cache schemes, such as trace cache, (fixed-sized) block cache, and variable-sized block cache, have helped improve instruction fetch bandwidth beyond the conventional instruction caches. Trace- and block-caches function by capturing the dynamic sequence of instructions. For industry standard benchmarks (e.g., SPEC2000), performance comparison of various configurations of these caches using simulations can take days or even weeks. In this paper, we demonstrate that neural network models can be time-efficient alternatives to the simulations. The models are able to predict the multi-variate and non-linear behavior of trace- and block-caches, in terms of trace miss rate and average trace length. The models can be potentially used in compiler optimization or in pedagogical settings.

Performance comparison of various configurations of single-pump dispersion-compensating Raman/EDFA hybrid amplifiers

We show experimental performance comparison of three types of single-pump highly efficient dispersion-compensating Raman/erbium-doped fiber amplifier (EDFA) hybrid amplifiers with respect to gain, noise figure (NF), and stimulated Brillouin scattering (SBS)-induced penalty: Raman/EDFA hybrid amplifiers recycling residual Raman pump in a cascaded erbium-doped fiber located either after (Type I) or prior to (Type II) a dispersion-compensating fiber, and a Raman assisted EDFA (Type III). Type I shows high small-signal gains, moderate large-signal gains, moderate NFs, and high SBS tolerances. Type II shows high small-signal gains, low NFs, and low SBS tolerances. Type III shows moderate small-signal gains, high large-signal gains, moderate NFs, and high SBS tolerances.

Q -sensitivity of certain RC active filters to gain-bandwidth product

The second-order effects of the gain-bandwidth product (g.b.w.) of operational amplifiers on the pole Q of certain active RC bandpass filters have been studied. These studies enable an accurate comparison of various configurations of active filters to determine their utility over a wide range of complex pole frequencies.