Search results for: solar radiation pressure

Authors: Sara Bahariderakhshan, Morteza Ahmadifar

Abstract:

Leakage is one of the most important problems that water distribution networks face which first reason is high-pressure existence. There are many approaches to control this excess pressure, which using pressure reducing valves (PRVs) or reducing pipe diameter are ones. In the other hand, Pumps are using electricity or fossil fuels to supply needed pressure in distribution networks but excess pressure are made in some branches due to topology problems and water networks’ variables therefore using pressure valves will be inevitable. Although using PRVs is inevitable but it leads to waste electricity or fuels used by pumps because PRVs just waste excess hydraulic pressure to lower it. Pumps working in reverse or Pumps as Turbine (called PaT in this article) are easily available and also effective sources of reducing the equipment cost in small hydropower plants. Urban areas of developing countries are facing increasing in area and maybe water scarcity in near future. These cities need wider water networks which make it hard to predict, control and have a better operation in the urban water cycle. Using more energy and, therefore, more pollution, slower repairing services, more user dissatisfaction and more leakage are these networks’ serious problems. Therefore, more effective systems are needed to monitor and act in these complicated networks than what is used now. In this article a new approach is proposed and evaluated: Using PAT to produce enough energy for remote valves and sensors in the water network. These sensors can be used to determine the discharge, pressure, water quality and other important network characteristics. With the help of remote valves pipeline discharge can be controlled so Instead of wasting excess hydraulic pressure which may be destructive in some cases, obtaining extra pressure from pipeline and producing clean electricity used by remote instruments is this articles’ goal. Furthermore due to increasing the area of the network there is unwanted high pressure in some critical points which is not destructive but lowering the pressure results to longer lifetime for pipeline networks without users’ dissatisfaction. This strategy proposed in this article, leads to use PaT widely for pressure containment and producing energy needed for remote valves and sensors like what happens in supervisory control and data acquisition (SCADA) systems which make it easy for us to monitor, receive data from urban water cycle and make any needed changes in discharge and pressure of pipelines easily and remotely. This is a clean project of energy production without significant environmental impacts and can be used in urban drinking water networks, without any problem for consumers which leads to a stable and dynamic network which lowers leakage and pollution.

Keywords: new energies, pump as turbine, drinking water, distribution network, remote control equipments

Procedia PDF Downloads 463

Authors: Siddharth Ahuja, T. M. Muruganandam

Abstract:

An analytical investigation is performed to study the unsteady response of a one-dimensional, non-linear dynamic shock system to external downstream pressure perturbations in a supersonic flow in a varying area duct. For a given pressure ratio across a wind tunnel, the normal shock's location can be computed as per one-dimensional steady gas dynamics. Similarly, for some other pressure ratio, the location of the normal shock will change accordingly, again computed using one-dimensional gas dynamics. This investigation focuses on the small-time interval between the first steady shock location and the new steady shock location (corresponding to different pressure ratios). In essence, this study aims to shed light on the motion of the shock from one steady location to another steady location. Further, this study aims to create the foundation of the Unsteady Gas Dynamics field enabling further insight in future research work. According to the new pressure ratio, a pressure pulse, generated at the exit of the tunnel which travels and perturbs the shock from its original position, setting it into motion. During such activity, other numerous physical phenomena also happen at the same time. However, three broad phenomena have been focused on, in this study - Traversal of a Wave, Fluid Element Interactions and Wave Interactions. The above mentioned three phenomena create, alter and kill numerous waves for different conditions. The waves which are created by the above-mentioned phenomena eventually interact with the shock and set it into motion. Numerous such interactions with the shock will slowly make it settle into its final position owing to the new pressure ratio across the duct, as estimated by one-dimensional gas dynamics. This analysis will be extremely helpful in the prediction of inlet 'unstart' of the flow in a supersonic engine intake and its prominence with the incoming flow Mach number, incoming flow pressure and the external perturbation pressure is also studied to help design more efficient supersonic intakes for engines like ramjets and scramjets.

Keywords: analytical investigation, compression and expansion waves, fluid element interactions, shock trajectory, supersonic flow, unsteady gas dynamics, varying area duct, wave interactions

Procedia PDF Downloads 217

Authors: Hilal Keklicek, Baris Cetin, Yeliz Salci, Ayla Fil, Umut Altinkaynak, Kadriye Armutlu

Abstract:

Objectives and Goals: Spasticity is a common symptom characterized with a velocity dependent increase in tonic stretch reflexes (muscle tone) in patient with multiple sclerosis (MS). Hypertonic muscles affect the normal plantigrade contact by disturbing accommodation of foot to the ground while walking. It is important to know the differences between healthy and neurologic foot features for management of spasticity related deformities and/or determination of rehabilitation purposes and contents. This study was planned with the aim of investigating the dynamic plantar pressure distribution in individuals with MS and determining the differences between healthy individuals (HI). Methods: Fifty-five individuals with MS (108 foot with spasticity according to Modified Ashworth Scale) and 20 HI (40 foot) were the participants of the study. The dynamic pedobarograph was utilized for evaluation of dynamic loading parameters. Participants were informed to walk at their self-selected speed for seven times to eliminate learning effect. The parameters were divided into 2 categories including; maximum loading pressure (N/cm2) and time of maximum pressure (ms) were collected from heal medial, heal lateral, mid foot, heads of first, second, third, fourth and fifth metatarsal bones. Results: There were differences between the groups in maximum loading pressure of heal medial (p < .001), heal lateral (p < .001), midfoot (p=.041) and 5th metatarsal areas (p=.036). Also, there were differences between the groups the time of maximum pressure of all metatarsal areas, midfoot, heal medial and heal lateral (p < .001) in favor of HI. Conclusions: The study provided basic data about foot pressure distribution in individuals with MS. Results of the study primarily showed that spasticity of lower extremity muscle disrupted the posteromedial foot loading. Secondarily, according to the study result, spasticity lead to inappropriate timing during load transfer from hind foot to forefoot.

Keywords: multiple sclerosis, plantar pressure distribution, gait, norm values

Procedia PDF Downloads 320

Authors: Morteza Ahmadifar, Sarah Bahari Derakhshan

Abstract:

Leakage is one of the most important problems that water distribution networks face which first reason is high-pressure existence. There are many approaches to control this excess pressure, which using pressure reducing valves (PRVs) or reducing pipe diameter are ones. On the other hand, Pumps are using electricity or fossil fuels to supply needed pressure in distribution networks but excess pressure are made in some branches due to topology problems and water networks’ variables, therefore using pressure valves will be inevitable. Although using PRVs is inevitable but it leads to waste electricity or fuels used by pumps because PRVs just waste excess hydraulic pressure to lower it. Pumps working in reverse or Pumps as Turbine (called PAT in this article) are easily available and also effective sources of reducing the equipment cost in small hydropower plants. Urban areas of developing countries are facing increasing in area and maybe water scarcity in near future. These cities need wider water networks which make it hard to predict, control and have a better operation in the urban water cycle. Using more energy and therefore more pollution, slower repairing services, more user dissatisfaction and more leakage are these networks’ serious problems. Therefore, more effective systems are needed to monitor and act in these complicated networks than what is used now. In this article a new approach is proposed and evaluated: Using PAT to produce enough energy for remote valves and sensors in the water network. These sensors can be used to determine the discharge, pressure, water quality and other important network characteristics. With the help of remote valves pipeline discharge can be controlled so Instead of wasting excess hydraulic pressure which may be destructive in some cases, obtaining extra pressure from pipeline and producing clean electricity used by remote instruments is this articles’ goal. Furthermore, due to increasing the area of network there is unwanted high pressure in some critical points which is not destructive but lowering the pressure results to longer lifetime for pipeline networks without users’ dissatisfaction. This strategy proposed in this article, leads to use PAT widely for pressure containment and producing energy needed for remote valves and sensors like what happens in supervisory control and data acquisition (SCADA) systems which make it easy for us to monitor, receive data from urban water cycle and make any needed changes in discharge and pressure of pipelines easily and remotely. This is a clean project of energy production without significant environmental impacts and can be used in urban drinking water networks, without any problem for consumers which leads to a stable and dynamic network which lowers leakage and pollution.

Keywords: clean energies, pump as turbine, remote control, urban water distribution network

Procedia PDF Downloads 393

Authors: Nuria Rubio, María Campo, Joana Ruiz, Paola Vecino

Abstract:

Renewable energies have been proposed for some years as a solution to the ecological crisis caused by traditional fuels. The installation of solar parks for electricity production is therefore necessary for a transition to cleaner energy. Additionally, spaces occupied by solar parks can be ideal places for biodiversity promotion consisting in controlled areas allowing free transit of numerous animal species in absence of phytosanitary products or other substances commonly used in rural areas. The main objective of this project is increasing local biodiversity. Secondary objectives include the installation of beehives with Apis mellifera iberiensis swarms (native honeybee species), the monitoring and periodic evaluation of the state of health and demographic progression of these swarms and study of biodiversity increase in these areas, mainly due to the presence of Apis mellifera iberiensis. Prior to bee-hives installation, a preliminary study of the area is carried out to quantify floral load, biocenosis and geo-climatological characteristics of the area of study for determining the optimal number of hives for the benefit of the local ecosystem. Once beehives set up, the bee-swarms health status is monitored and evaluated quarterly using monitoring systems. Parameters studies are weight, humidity inside the hive, external and internal temperature, and sound inside the hive. Furthermore, a biodiversity study of the area was conducted by direct observation and quantification of species (S) in the area of bee-foraging (1 km around the beehives). A great diversity of species has been detected in the area of study. Therefore, the population of Apis mellifera iberiensis is not displacing other pollinators in the area, on the contrary, results show that it is contributing to the pollination of the different plant species enhancing wild bees’ biodiversity.

Keywords: biodiversity, honeybee, pollination, solar park

Procedia PDF Downloads 54

Authors: Ruchi Vyas, Sanjay Singh, Rashmi Sisodia

Abstract:

Chlorophytum borivillianum root extract (CBE) was chosen as a reducing agent to fabricate silver nanoparticles with the aim of studying its radioprotective efficacy. The formation of synthesized nanoparticles was characterized by UV–visible analysis (UV–vis), Fourier transform infra-red (FT-IR), Transmission electron microscopy (TEM), Scanning electron microscope (SEM). TEM analysis showed particles size in the range of 20-30 nm. For this study, Swiss albino mice were selected from inbred colony and were divided into 4 groups: group I- control (irradiated-6 Gy), group II- normal (vehicle treated), group III- plant extract alone and group IV- CB-AgNPs (dose of 50 mg/kg body wt./day) administered orally for 7 consecutive days before irradiation to serve as experimental. CB-AgNPs pretreatment rendered significant increase in body weight and testes weight at various post irradiation intervals in comparison to irradiated group. Supplementation of CB-AgNPs reversed the adverse effects of gamma radiation on biochemical parameters as it notably ameliorated the elevation in lipid peroxidation and decline in glutathione concentration in testes. These observations indicate the radio-protective potential of CB-AgNPs in testicular constituents against gamma irradiation in mice.

Keywords: Chlorophytum borivillianum, gamma radiation, radioprotective, silver nanoparticles

Procedia PDF Downloads 148

Authors: Harminder Singh, Rupinder Kaur

Abstract:

Peach is primarily a temperate fruit, but its low chilling cultivars are grown quite successfully in the sub-tropical climate as well. The area under peach cultivation is picking up rapidly in the sub tropics of northern India due to higher return on a unit area basis, availability of suitable peach cultivar and their production technology. Information on the use of different training systems on peach in the sub tropics is inadequate. In this investigation, conducted at Punjab Agricultural University, Ludhiana (Punjab), India, the trees of the Shan-i-Punjab peach were planted at four different spacings i.e. 6.0x3.0m, 6.0x2.5m, 4.5x3.0m and 4.5x2.5m and were trained to central leader system. The total radiation interception and penetration in the upper and lower canopy parts were higher in 6x3.0m and 6x2.5m planted trees as compared to other spacings. Average radiation interception was maximum in the upper part of the tree canopy, and it decreased significantly with the depth of the canopy in all the spacings. Tree planted at wider spacings produced more vegetative (tree height, tree girth, tree spread and canopy volume) and reproductive growth (flower bud density, number of fruits and fruit yield) per tree but productivity was maximum in the closely planted trees. Fruits harvested from the wider spaced trees were superior in fruit quality (size, weight, colour, TSS and acidity) and matured earlier than those harvested from closed spaced trees.

Keywords: quality, radiation, spacings, yield

Procedia PDF Downloads 188

Authors: Ehsan Atash Zaban, Mehdi Beyk

Abstract:

In recent years, concerns over the depletion of non-renewable fuels and environmental pollution have led countries around the world to look for alternative energy sources for these fuels. An energy source that can have the necessary reliability, be a suitable alternative to fossil fuels, be technologically achievable, comply with environmental standards to the maximum, and at the same time cause countries to meet domestic consumption for electricity production. Iran is one of the richest countries in the world in terms of various energy sources because, on the one hand, it has extensive sources of fossil and non-renewable fuels such as oil and gas, and on the other hand, it has great potential for renewable energy. In this paper, the potential of renewable energy in Iran, which includes solar, wind, geothermal, hydrogen technology, and biomass, has been reviewed and analyzed.

Keywords: renewable energy, solar stations, wind, biomass, hydropower

Procedia PDF Downloads 91

Authors: Vladimir Viktorov, Readul Mahmud, Carmen Visconte

Abstract:

In the present study, a new passive micromixer based on SAR principle, combining the operation concepts of known Chain and H mixers, called C-H micromixer, is developed and studied. The efficiency and the pressure drop of the C-H mixer along with two known SAR passive mixers named Chain and Tear-drop were investigated numerically at Reynolds numbers up to 100, taking into account species transport. At the same time experimental tests of the Chain and Tear-drop mixers were carried out at low Reynolds number, in the 0.1≤Re≤4.2 range. Numerical and experimental results coincide considerably, which validate the numerical simulation approach. Results show that mixing efficiency of the Tear-drop mixer is good except at the middle range of Reynolds number but pressure drop is too high; conversely the Chain mixer has moderate pressure drop but relatively low mixing efficiency at low and middle Re numbers. Whereas, the C-H mixer gives excellent mixing efficiency at all range of Re numbers. In addition, the C-H mixer shows respectively about 3 and 2 times lower pressure drop than the Tear-drop mixer and the Chain mixer.

Keywords: CFD, micromixing, passive micromixer, SAR

Procedia PDF Downloads 308

Authors: Siddig H. Hamad, Salah M. Al-Eid, Fahad M. Al-Jassas

Abstract:

Composite samples of minced chicken were vacuum-packaged and pressure treated at 300, 400, 450 and 500 MPa in a Stansted 'FOOD-LAB' model S-FL-850-9-W high hydrostatic pressure research apparatus (Stansted Fluid Power Ltd., Stansted, UK). Treated and untreated samples were then stored at 3°C, and microbial content as well as some chemical and physical properties monitored. The microbial load of the untreated samples reached the spoilage level of 107 cfu/g in about one week, resulting in bad smell and dark brown color. The pressure treatments reduced total bacterial counts by about 1.8 to 3.2 log10 cycles and reduced counts of Enterobacteriaceae and Salmonella to non-detectable levels. The color of meat was slightly affected, but pH, moisture content and the oxidation products of lipids were not substantially changed. The treatment killed mainly gram negative bacteria but also caused sub-lethal injury to part of the population resulting in prolonged lag phase. The population not killed by the 350 to 450 MPa treatments grew relatively slowly during storage, and its loads reached spoilage level in 4 to 6 weeks, while the load of the population treated at 500 MPa did not reach this level till the end of a storage period of 9 weeks.

Keywords: chicken, cold storage, microbial spoilage, high hydrostatic pressure

Procedia PDF Downloads 244

Authors: Punit Kumar, Niraj Kumar

Abstract:

The traction behavior of lubricants with the linear pressure-viscosity response in EHL line contacts is investigated numerically for smooth as well as rough surfaces. The analysis involves the simultaneous solution of Reynolds, elasticity and energy equations along with the computation of lubricant properties and surface temperatures. The temperature modified Doolittle-Tait equations are used to calculate viscosity and density as functions of fluid pressure and temperature, while Carreau model is used to describe the lubricant rheology. The surface roughness is assumed to be sinusoidal and it is present on the nearly stationary surface in near-pure sliding EHL conjunction. The linear P-V oil is found to yield much lower traction coefficients and slightly thicker EHL films as compared to the synthetic oil for a given set of dimensionless speed and load parameters. Besides, the increase in traction coefficient attributed to surface roughness is much lower for the former case. The present analysis emphasizes the importance of employing realistic pressure-viscosity response for accurate prediction of EHL traction.

Keywords: EHL, linear pressure-viscosity, surface roughness, traction, water/glycol

Procedia PDF Downloads 382

Authors: Nabil Saad, David Morgan, Manish Gupta

Abstract:

Visibility has become a key component of air quality and is regulated in many areas by environmental laws such as the EPA Clean Air Act and Regional Haze Rule. Typically, visibility is calculated by estimating the optical absorption and scattering of both gases and aerosols. A major component of the aerosols’ climatic effect is due to their scattering and absorption of solar radiation, which are governed by their optical and physical properties. However, the accurate assessment of this effect on global warming, climate change, and air quality is made difficult due to uncertainties in the calculation of single scattering albedo (SSA). Experimental complications arise in the determination of the single scattering albedo of an aerosol particle since it requires the simultaneous measurement of both scattering and extinction. In fact, aerosol optical absorption, in particular, is a difficult measurement to perform, and it’s often associated with large uncertainties when using filter methods or difference methods. In this presentation, we demonstrate the use of a new open-path Optical Extinction Analyzer (OEA) in conjunction with a nephelometer and two particle sizers, emphasizing the benefits that co-employment of the OEA offers to derive the complex refractive index of aerosols and their single scattering albedo parameter. Various use cases, data reproducibility, and instrument calibration will also be presented to highlight the value proposition of this novel Open-Path OEA.

Keywords: aerosols, extinction, visibility, albedo

Procedia PDF Downloads 90

Authors: Radegunda Kessy, Justus Ochieng, Victor Afari-Sefa, Takemore Chagomoka, Ngoni Nenguwo

Abstract:

Vegetables are excellent sources of dietary fiber, vitamins, and minerals which constitute an indispensable constituent of diets, but in Tanzania and other Sub-Saharan African countries, they are not readily available all year round due to seasonal variations in the production cycle. Drying of vegetables is one of the traditional methods for food preservation known to man. The Dodoma and Singida regions of Tanzania are characterized by semi-arid agro-climate, thereby experiencing short seasonal supply of fresh vegetables followed by long drought in which dried vegetables become an alternative to meet high household demands. A primary survey of 244 of rural consumers was carried out to understand how knowledge, attitudes, and perceptions of rural consumers affect consumption of dried vegetables. The sample respondents were all found to be aware of open sun drying of vegetables while less than 50% of them were aware of solar-dried vegetables. Consumers were highly concerned with the hygiene, nutritional values, taste, drying method, freshness, color of dried vegetables, timely availability and easiness of cooking as important factors they consider before they purchase dried vegetables. Logit model results show that gender, income, years of consuming dried vegetables, awareness of the importance of solar dried vegetables vis-à-vis sun-dried alternatives and employment status influenced rural consumer’s decision to purchase dried vegetables. Preference on dried vegetables differs across the regions which are also important considerations for any future planned interventions. The findings imply that development partners and policymakers need to design better social marketing and promotion techniques for the enhanced adoption of solar drying technology, which will greatly improve the quality and utilization of dried vegetables by target households.

Keywords: dried vegetables, postharvest management, sun drying, solar drying

Procedia PDF Downloads 198

Authors: Zahzouh Zoubir, Bouzaouit Azzeddine, Gahgah Mounir

Abstract:

The use of more and more electronic power switches with a nonlinear behavior generates non-sinusoidal currents in distribution networks, which causes damage to domestic and industrial equipment. The multi-level shunt power active filter is subsequently shown to be an adequate solution to the problem raised. Nevertheless, the difficulty of adjusting the active filter DC supply voltage requires another technology to ensure it. In this article, a photovoltaic generator is associated with the DC bus power terminals of the active filter. The proposed system consists of a field of solar panels, three multi-level voltage inverters connected to the power grid and a non-linear load consisting of a six-diode rectifier bridge supplying a resistive-inductive load. Current control techniques of active and reactive power are used to compensate for both harmonic currents and reactive power as well as to inject active solar power into the distribution network. An algorithm of the search method of the maximum power point of type Perturb and observe is applied. Simulation results of the system proposed under the MATLAB/Simulink environment shows that the performance of control commands that reassure the solar power injection in the network, harmonic current compensation and power factor correction.

Keywords: Actif power filter, MPPT, pertub&observe algorithm, PV array, PWM-control

Procedia PDF Downloads 338

Authors: Bo Hyun Kim, Sarng Woo Karng

Abstract:

In constructing a hydrogen refueling station, minimizing the volume and reducing the number of banks enable lessening the construction cost. This study aims at performing the dynamic simulation on 250 kg/day of a refueling station for light-duty vehicles. The primary compressor boosts hydrogen from a tube trailer of 250 to 480 bar and stores it in a medium-pressure bank. Then, additional compression of hydrogen from 480 to 900 bar is carried out and stored in a high-pressure bank. Economic analysis was conducted considering the amount of electricity consumed by compression corresponding to the volume and the number of banks (cascade system) in charging mode. NIST REFPROP was selected as the equation of state on the ASPEN HYSYS for thermodynamic analysis of the tube-trailer, the compressors, the chillers, and the banks. Compared to a single high-pressure bank system of 3000 L, the volume of the cascade high-pressure banks (bank1: 250 L and bank 2: 1850 L) was reduced by 30%, and the power consumption of the chiller for precooling was also decreased by 16%.

Keywords: light-duty vehicles, economic analysis, cascade system, hydrogen refueling station

Procedia PDF Downloads 92

Authors: Jae-Ho Jang, Jung-Soo Kim, Byung-Jun Kim, Dae-Geun Nam, Uoo-Chang Jung, Yoon-Suk Choi

Abstract:

Low alloy steels are widely used for pressure vessels, spent fuel storage, and steam generators required to withstand the internal pressure and prevent unexpected failure in nuclear power plants, which these may suffer embrittlement by high levels of radiation and heat for a long period. Therefore, it is important to improve mechanical properties of low alloy steels for the integrity of structure materials at an early stage of fabrication. Recently, it showed that a double austenitizing and tempering (DTA) process resulted in a significant improvement of strength and toughness by refinement of prior austenite grains. In this study, it was investigated that the mechanism of improving mechanical properties according to the change of microstructure by the second fully austenitizing temperature of the DAT process for low alloy steel required the structural integrity. Compared to conventional single austenitizing and tempering (SAT) process, the tensile elongation properties have improved about 5%, DBTTs have obtained result in reduction of about -65℃, and grain size has decreased by about 50% in the DAT process conditions. Grain refinement has crack propagation interference effect due to an increase of the grain boundaries and amount of energy absorption at low temperatures. The higher first austenitizing temperature in the DAT process, the more increase the spheroidized carbides and strengthening the effect of fine precipitates in the ferrite grain. The area ratio of the dimple in the transition area has increased by proportion to the effect of spheroidized carbides. This may the primary mechanisms that can improve low-temperature toughness and elongation while maintaining a similar hardness and strength.

Keywords: double austenitizing, Ductile Brittle transition temperature, grain refinement, heat treatment, low alloy steel, low-temperature toughness

Procedia PDF Downloads 510

Authors: Kyoung Hoon Kim

Abstract:

Organic Rankine Cycle (ORC) has potential in reducing fossil fuels and relaxing environmental problems. In this work performance analysis of ORC is conducted based on the second law of thermodynamics for recovery of low temperature heat source from 100°C to 140°C using R134a as the working fluid. Effects of system parameters such as turbine inlet pressure or source temperature are theoretically investigated on the exergy destructions (anergies) at various components of the system as well as net work production or exergy efficiency. Results show that the net work or exergy efficiency has a peak with respect to the turbine inlet pressure when the source temperature is low, however, increases monotonically with increasing turbine inlet pressure when the source temperature is high.

Keywords: Organic Rankine Cycle (ORC), low temperature heat source, exergy, source temperature

Procedia PDF Downloads 451

Authors: M. Al Huwayz, A. Salhi, S. Alhassan, S. Alotaibi, A. Almalki, M.Almunyif, A. Alhassni, M. Henini

Abstract:

Recently, there has been much research carried out to investigate quantum dots (QDs) lasers with the aim to increase the gain of quantum well lasers. However, one of the difficulties with these structures is that electrically active defects can lead to serious issues in the performance of these devices. It is therefore essential to fully understand the types of defects introduced during the growth and/or the fabrication process. In this study, the effects of Gamma radiation on the electrically active defects in p-i-n InAs/InGaAsQDs laser structures grown by Molecular Beam Epitaxy (MBE) technique on GaAs substrates were investigated. Deep Level Transient Spectroscopy (DLTS), current-voltage (I-V), and capacitance-voltage (C-V) measurements were performed to explore these effects on the electrical properties of these QDs lasers. I-V measurements showed that as-grown sample had better electrical properties than the irradiated sample. However, DLTS and Laplace DLTS measurements at different reverse biases revealed that the defects in the-region of the p-i-n structures were decreased in the irradiated sample. In both samples, a trap with an activation energy of ~ 0.21 eV was assigned to the well-known defect M1 in GaAs layers

Keywords: quantum dots laser structures, gamma radiation, DLTS, defects, nAs/IngaAs

Procedia PDF Downloads 187

Authors: V. Polenta, S. D. Garvey, D. Chronopoulos, A. C. Long, H. P. Morvan

Abstract:

A parametric study on circular thin-walled pipes subjected to pure bending is performed. Both straight and curved pipes are considered. Ratio D/t, initial pipe curvature and internal pressure are the parameters varying in the analyses. The study is mainly FEA-based. It is found that negative curvatures (opposite to bending moment) considerably increase stiffness and buckling limit of the pipe when no internal pressure is acting and, similarly, positive curvatures decrease the stiffness and buckling limit. For internal pressurised pipes the effects of initial pipe curvature are less relevant. Results show that this phenomenon is in relationship with the cross-section deformation due to bending moment, which undergoes relevant ovalisation for no pressurised pipes and little ovalisation for pressurised pipes.

Keywords: buckling, curved pipes, internal pressure, ovalisation, pure bending, thin-walled pipes

Procedia PDF Downloads 376

Authors: Seyedeh Mozhgan Seyed Talebi, Chih -Hao Lee

Abstract:

With an abrupt rise in the power conservation efficiency (PCE) of perovskite solar cells (PSCs) within a short span of time, the toxicity of lead was raised as a major hurdle in the path toward their commercialization. In the present research, a systematic investigation of the electrical and optical characteristics of the all-inorganic CsSnI₃ perovskite absorber layer was performed with the Vienna Ab Initio Simulation Package (VASP) using the projector-augmented wave method. The presence of inorganic halide perovskite offers the advantages of enhancing the degradation resistance of the device, reducing the cost of cells, and minimizing the recombination of generated carriers. The simulated standard device using a 1D simulator like solar cell capacitance simulator (SCAPS) version 3308 involves FTO/n-TiO₂/CsSnI₃ Perovskite absorber/Spiro OmeTAD HTL/Au contact layer. The variation in the device design key parameters such as the thickness and defect density of perovskite absorber, hole transport layer and electron transport layer and interfacial defects are examined with their impact on the photovoltaic characteristic parameters. The effect of an increase in operating temperature from 300 K to 400 K on the performance of CsSnI3-based perovskite devices is also investigated. The optimized standard device at room temperature shows the highest PCE of 25.18 % with FF of 75.71 %, Voc of 0.96 V, and Jsc of 34.67 mA/cm². The outcomes and interpretation of different inorganic Cu-based HTLs presence, such as CuSCN, Cu₂O, CuO, CuI, SrCu₂O₂, and CuSbS₂, here represent a critical avenue for the possibility of fabricating high PCE perovskite devices made of stable, low-cost, efficient, safe, and eco-friendly all-inorganic materials like CsSnI₃ perovskite light absorber.

Keywords: CsSnI₃, hole transporting layer (HTL), lead-free perovskite solar cell, SCAPS-1D software

Procedia PDF Downloads 87

Authors: Othmane Fahim, Naoual Belouaggadia. Charifa David, Mohamed Ezzine

Abstract:

To make better use of cooling resources, systems have been derived on the basis of the use of night radiator systems for heat pumping. Using the TRNSYS tool we determined the influence of the climatic characteristics of the two zones in Morocco on the temperature of the outer surface of a Photovoltaic Thermal Panel “PVT” made of aluminum. The proposal to improve the performance of the panel allowed us to have little heat absorption during the day and give the same performance of a panel made of aluminum at night. The variation in the granite-based panel temperature recorded a deviation from the other materials of 0.5 °C, 2.5 °C on the first day respectively in Marrakech and Casablanca, and 0.2 °C and 3.2 °C on the second night. Power varied between 110.16 and 32.01 W/m² marked in Marrakech, to be the most suitable area to practice night cooling by night radiation.

Keywords: smart buildings, energy efficiency, Morocco, radiative cooling

Procedia PDF Downloads 153

Authors: Andrew Hwang

Abstract:

The average American worker sits for thirteen hours a day, often with poor posture and infrequent breaks, which can lead to health issues and back problems. The Smart Cushion was created to alert individuals of their poor postures, and may potentially alleviate back problems and correct poor posture. The Smart Cushion is a portable, rectangular, foam cushion, with five strategically placed pressure sensors, that utilizes an Arduino Uno circuit board and specifically designed software, allowing it to collect data from the five pressure sensors and store the data on an SD card. The data is then compiled into graphs and compared to controlled postures. Before volunteers sat on the cushion, their levels of back pain were recorded on a scale from 1-10. Data was recorded for an hour during sitting, and then a new, corrected posture was suggested. After using the suggested posture for an hour, the volunteers described their level of discomfort on a scale from 1-10. Different patterns of sitting postures were generated that were able to serve as early warnings of potential back problems. By using the Smart Cushion, the areas where different volunteers were applying the most pressure while sitting could be identified, and the sitting postures could be corrected. Further studies regarding the relationships between posture and specific regions of the body are necessary to better understand the origins of back pain; however, the Smart Cushion is sufficient for correcting sitting posture and preventing the development of additional back pain.

Keywords: Arduino Sketch Algorithm, biomedical technology, pressure sensors, Smart Cushion

Procedia PDF Downloads 134

Authors: Zied Guidara, Alexander Morgenstern, Aref Younes Maalej

Abstract:

In this paper, a desiccant solar unit for air conditioning and desalination is presented first. Secondly, a dynamic modelling study of the desiccant wheel is developed. After that, a simulation study and an experimental investigation of the behaviour of desiccant wheel are developed. The experimental investigation is done in the chamber of commerce in Freiburg-Germany. Indeed, the variations of calculated and measured temperatures and specific humidity of dehumidified and rejected air are presented where a good agreement is found when comparing the model predictions with experimental data under the considered range of operating conditions. Finally, the study of the compartments of desalination and water condensation shows that the unit can produce an acceptable quantity of water at the same time of the air conditioning operation.

Keywords: air conditioning, desalination, condensation, design, desiccant wheel

Procedia PDF Downloads 503

Authors: Aparna Bhat, Rajeshwari Hegde

Abstract:

Renewable energy sources also called non-conventional energy sources that are continuously replenished by natural processes. For example, solar energy, wind energy, bio-energy- bio-fuels grown sustain ably), hydropower etc., are some of the examples of renewable energy sources. A renewable energy system converts the energy found in sunlight, wind, falling-water, sea-waves, geothermal heat, or biomass into a form, we can use such as heat or electricity. Most of the renewable energy comes either directly or indirectly from sun and wind and can never be exhausted, and therefore they are called renewable. This paper presents a review about conventional and renewable energy scenario of India. The paper also presents current status, major achievements and future aspects of renewable energy in India and implementing renewable for the future is also been presented.

Keywords: solar energy, renewabe energy, wind energy, bio-diesel, biomass, feedin

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Authors: Michaela Chovancova, Pavel Niedoba

Abstract:

For the treatment of acute and chronic lung diseases it is preferred to deliver medicaments by inhalation. The drug is delivered directly to tracheobronchial tree. This way allows the given medicament to get directly into the place of action and it makes rapid onset of action and maximum efficiency. The transport of aerosol particles in the particular part of the lung is influenced by their size, anatomy of the lungs, breathing pattern and airway resistance. This article deals with calculation of airway resistance in the lung model of Horsfield. It solves the problem of determination of the pressure losses in bifurcation and thus defines the pressure drop at a given location in the bronchial tree. The obtained data will be used as boundary conditions for transport of aerosol particles in a central part of bronchial tree realized by Computational Fluid Dynamics (CFD) approach. The results obtained from CFD simulation will allow us to provide information on the required particle size and optimal inhalation technique for particle transport into particular part of the lung.

Keywords: human lungs, bronchial tree, pressure losses, airways resistance, flow, breathing

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Authors: Peter A. L’vov, Roman S. Konovalov, Alexey A. L’vov

Abstract:

The paper presents the advanced digital modification of the conventional current loop circuit for pressure piezoelectric transducers. The optimal DSP algorithms of current loop responses by the maximum likelihood method are applied for diminishing of measurement errors. The loop circuit has some additional advantages such as the possibility to operate with any type of resistance or reactance sensors, and a considerable increase in accuracy and quality of measurements to be compared with AC bridges. The results obtained are dedicated to replace high-accuracy and expensive measuring bridges with current loop circuits.

Keywords: current loop, maximum likelihood method, optimal digital signal processing, precise pressure measurement

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Authors: Diamant Irene, Dar Tamar

Abstract:

Burnout, conceptualized within the framework of stress research, is to a large extent a result of a threat on resources of time or a feeling of time shortage. In reaction to numerous tasks, deadlines, high output, management of different duties encompassing work-home conflicts, many individuals experience ‘time pressure’. Time pressure is characterized as the perception of a lack of available time in relation to the amount of workload. It can be a result of local objective constraints, but it can also be a chronic attribute in coping with life. As such, time pressure is associated in the literature with general stress experience and can therefore be a direct, contributory burnout factor. The present study examines the relation of chronic time pressure – feeling of time shortage and of being rushed, with another central aspect in subjective temporal experience - time perspective. Time perspective is a stable personal disposition, capturing the extent to which people subjectively remember the past, live the present and\or anticipate the future. Based on Hobfoll’s Conservation of Resources Theory, it was hypothesized that individuals with chronic time pressure would experience a permanent threat on their time resources resulting in relatively increased burnout. In addition, it was hypothesized that different time perspective profiles, based on Zimbardo’s typology of five dimensions – Past Positive, Past Negative, Present Hedonistic, Present Fatalistic, and Future, would be related to different magnitudes of chronic time pressure and of burnout. We expected that individuals with ‘Past Negative’ or ‘Present Fatalist’ time perspectives would experience more burnout, with chronic time pressure being a moderator variable. Conversely, individuals with a ‘Present Hedonistic’ - with little concern with the future consequences of actions, would experience less chronic time pressure and less burnout. Another temporal experience angle examined in this study is the difference between the actual distribution of time (as in a typical day) versus desired distribution of time (such as would have been distributed optimally during a day). It was hypothesized that there would be a positive correlation between the gap between these time distributions and chronic time pressure and burnout. Data was collected through an online self-reporting survey distributed on social networks, with 240 participants (aged 21-65) recruited through convenience and snowball sampling methods from various organizational sectors. The results of the present study support the hypotheses and constitute a basis for future debate regarding the elements of burnout in the modern work environment, with an emphasis on subjective temporal experience. Our findings point to the importance of chronic and stable temporal experiences, as time pressure and time perspective, in occupational experience. The findings are also discussed with a view to the development of practical methods of burnout prevention.

Keywords: conservation of resources, burnout, time pressure, time perspective

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Authors: L. Foudia, K. Haddadi, M. Reffas

Abstract:

First principles study of structural, elastic, electronic and optical properties of the monoclinic perovskite type ScRhO₃ has been reported using the pseudo-potential plane wave method within the local density approximation. The calculated lattice parameters, including the lattice constants and angle β, are in excellent agreement with the available experimental data, which proving the reliability of the chosen theoretical approach. Pressure dependence up to 20 GPa of the single crystal and polycrystalline elastic constants has been investigated in details using the strain-stress approach. The mechanical stability, ductility, average elastic wave velocity, Debye temperature and elastic anisotropy were also assessed. Electronic band structure and density of states (DOS) demonstrated its semiconducting nature showing a direct band gap of 1.38 eV. Furthermore, several optical properties, such as absorption coefficient, reflectivity, refractive index, dielectric function, optical conductivity and electron energy loss function, have been calculated for radiation up to 40 eV.

Keywords: ab-initio, perovskite, DFT, band gap

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Authors: Mohammad Hassan Heidari, Amir Hossein Goodarzi, Majid Azarniush

Abstract:

Radiation doses to tissues and organs were measured using the anthropomorphic phantom as an equivalent to the human body. When high-energy X-rays are externally applied to treat laryngeal cancer, the absorbed dose at the laryngeal lumen is lower than given dose because of air space which it should pass through before reaching the lesion. Specially in case of high-energy X-rays, the loss of dose is considerable. Three-dimensional absorbed dose distributions have been computed for high-energy photon radiation therapy of laryngeal and hypo pharyngeal cancers, using a coaxial pair of opposing lateral beams in fixed positions. Treatment plans obtained under various conditions of irradiation.

Keywords: 3D treatment planning, anthropomorphic phantom, larynx cancer, radiotherapy

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Authors: Danar Agus Susanto, Hermawan Febriansyah, Meilinda Ayundyahrini

Abstract:

The availability of spring water to meet people demand is often a problem, especially in tropical areas with very limited surface water sources, or very deep underground water. Although the technology and equipment of pumping system are available and easy to obtain, but in remote areas, the availability of pumping system is difficult, due to the unavailability of fuel or the lack of electricity. Solar Water Pumping System (SWPS) became one of the alternatives that can overcome these obstacles. In the tropical country, sunlight can be obtained throughout the year, even in remote areas. SWPS were already widely built in Indonesia, but many encounter problems during operations, such as decreased of efficiency; pump damaged, damaged of controllers or inverters, and inappropriate photovoltaic performance. In 2011, International Electrotechnical Commission (IEC) issued the IEC standard 62253:2011 titled Photovoltaic pumping systems - Design qualification and performance measurements. This standard establishes design qualifications and performance measurements related to the product of a solar water pumping system. National Standardization Agency of Indonesia (BSN) as the national standardization body in Indonesia, has not set the standard related to solar water pumping system. This research to study operational procedures of SWPS by adopting of IEC Standard 62253:2011 to be Indonesia Standard (SNI). This research used literature study and field observation for installed SWPS in Indonesia. Based on the results of research on SWPS already installed in Indonesia, IEC 62253: 2011 standard can improve efficiency and reduce operational failure of SWPS. SWPS installed in Indonesia still has GAP of 51% against parameters in IEC standard 62253: 2011. The biggest factor not being met is related to operating and maintenance handbooks for personnel that included operation and repair procedures. This may result in operator ignorance in installing, operating and maintaining the system. The Photovoltaic (PV) was also the most non-compliance factor of 71%, although there are 22 Indonesia Standard (SNI) for PV (modules, installation, testing, and construction). These research samples (installers, manufacturers/distributors, and experts) agreed on the parameter in the IEC standard 62253: 2011 able to improve the quality of SWPS in Indonesia. Recommendations of this study, that is required the adoption of IEC standard 62253:2011 into SNI to support the development of SWPS for remote areas in Indonesia.

Keywords: efficiency, inappropriate installation, remote areas, solar water pumping system, standard

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