Search results for: heat transfer characteristics

Authors: Sang Heon Han, Daejun Chang, Won Yang

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NOx reduction characteristics of syngas fuel were numerically investigated for the 2MW pilot scale heavy oil furnace of KITECH (Korea Institute of Industrial Technology). The secondary fuel and syngas was fed into the furnace with two purposes- partial replacement of main fuel and reburning of NOx. Some portion of syngas was fed into the flame zone to partially replace the heavy oil, while the other portion was fed into the furnace downstream to reduce NOx generation. The numerical prediction was verified by comparing it with the experimental results. Syngas of KITECH’s experiment, assumed to be produced from biomass, had very low calorific value and contained 3% hydrocarbon. This study investigated the precise behavior of NOx generation and NOx reduction as well as thermo-fluidic characteristics inside the furnace, which was unavailable with experiment. In addition to 3% hydrocarbon syngas, 5%, and 7% hydrocarbon syngas were numerically tested as reburning fuels to analyze the effect of hydrocarbon proportion to NOx reduction. The prediction showed that the 3% hydrocarbon syngas is as much effective as 7% hydrocarbon syngas in reducing NOx.

Keywords: syngas, reburning, heavy oil, furnace

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Authors: M. Fares, S. Mameri, I. Abdlani, K. Negara

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Neutron detectors in general, proportional counters gas filling based isotope 3He in particular are going to be essential for monitoring and control of certain nuclear facilities, monitoring of experimentation around neutron beams and channels nuclear research reactors, radiation protection instruments and other tools multifaceted exploration and testing of materials, etc. This work consists of a measurement campaign features two Proportional Counters 3He (3He: LND252/USA CP, CP prototype: 3He LND/DDM). This is to make a comparison study of a CP 3He LND252/USA reference one hand, and in the context of routine periodic monitoring of the characteristics of the detectors for controlling the operation especially for laboratory prototypes. In this paper, we have described the different characteristics of the detectors and the experimental protocols used. Tables of measures have been developed and the different curves were plotted. The experimental campaign at stake: 2 PC 3He were thus characterized: Their characteristics (sensitivity, energy pulse height distribution spectra, gas amplification etc.) Were identified: 01 PC 3He 1'' Type: prototype DEDIN/DDM, 01 PC 3He 1'' Type: LND252/USA.

Keywords: PC 3He, sensitivity, pulse height distribution spectra, gas amplification

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Authors: T. Rocha, P. Carvalho, S. Paredes, J. Henriques, A. Bianchi, V. Traver, A. Martinez

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The main goal of LINK project is to join competences in intelligent processing in order to create a research ecosystem to address two central scientific and technical challenges for personal health care (PHC) deployment: i) how to merge clinical evidence knowledge in computational decision support systems for PHC management and ii) how to provide achieve personalized services, i.e., solutions adapted to the specific user needs and characteristics. The final goal of one of the work packages (WP2), designated Sustainable Linking and Synergies for Excellence, is the definition, implementation and coordination of the necessary activities to create and to strengthen durable links between the LiNK partners. This work focuses on the strategy that has been followed to achieve the definition of the Research Tracks (RT), which will support a set of actions to be pursued along the LiNK project. These include common research activities, knowledge transfer among the researchers of the consortium, and PhD student and post-doc co-advisement. Moreover, the RTs will establish the basis for the definition of concepts and their evolution to project proposals.

Keywords: LiNK Twin European Project, personal health care, cardiovascular diseases, research tracks

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Authors: Robel Legese Meko

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Natural fibers have been used as end-of-life textiles and made into textile products which have become a well-proven and effective way of processing. Nowadays, resources to make primary synthetic fibers are becoming less and less as the world population is rising. Hence it is necessary to develop processes to fabricate textiles that are easily converted to composite materials. Acoustic comfort is closely related to the concept of sound absorption and includes protection against noise. This research paper presents an experimental study on sound absorption coefficients, for natural fiber composite materials: a natural fiber (Coir/Jute) with different blend proportions of raw materials mixed with rigid polyurethane foam as a binder. The natural fiber composite materials were characterized both acoustically (sound absorption coefficient SAC) and also in terms of heat transfer (thermal conductivity). The acoustic absorption coefficient was determined using the impedance tube method according to the ASTM Standard (ASTM E 1050). The influence of the structure of these materials on the sound-absorbing properties was analyzed. The experimental results signify that the porous natural coir/jute composites possess excellent performance in the absorption of high-frequency sound waves, especially above 2000 Hz, and didn’t induce a significant change in the thermal conductivity of the composites. Thus, the sound absorption performances of natural fiber composites based on coir/jute fiber materials promote environmentally friendly solutions.

Keywords: coir/jute fiber, sound absorption coefficients, compression molding, impedance tube, thermal insulating properties, SEM analysis

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Authors: A. Binnui, O. Kalinowska-Beszczynska, G. Shaw

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It is postulated that innovative deployment of entrepreneurial activities leads to firm's growth. This paper draws upon the key predictions of the core theories on entrepreneurship and innovation to formulate a conceptual framework which can be used to depict the casual chain of events from which entrepreneurs can manage more innovatively and ultimately deliver higher growth which benefits of the regional and national economies. It examines the key firm-based factors extracted from the theories, namely the characteristics of entrepreneurial hi-tech firms, characteristics of innovating firms, and firm growth dynamics that lead to enhanced economic growth. The framework postulates that the key determinants extracted such as entrepreneurial demographics, firm characteristic, skills and competencies, research and development, product/service characteristics, market development, financial of the firm and internationalization might lead to the survival and long term development of high-technology startups.

Keywords: innovative entrepreneurial activities, entrepreneuship, determinants, growth, hi-technology start-upws

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Authors: You-Lin Wu, Yi-Hsing Sung, Shih-Hung Lin, Jing-Jenn Lin

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Performance improvement in optoelectronic devices such as solar cells and photodetectors has been reported when a polymer/ZnO nanorods stack is used. Resistance switching of polymer/ZnO nanocrystals (or nanorods) hybrid has also gained a lot of research interests recently. It has been reported that high- and low-resistance states of a metal/insulator/metal (MIM) structure diode with a polystyrene (PS) and ZnO hybrid as the insulator layer can be switched by applied bias after a high-voltage forming process, while the same device structure merely with a PS layer does not show any forming behavior. In this work, we investigated the current-voltage (I-V) characteristics of an MIM device with a PS/ZnO nanorods stack deposited on fluorine-doped tin oxide (FTO) glass substrate. The ZnO nanorods were grown by a hydrothermal method using a mixture of zinc nitrate, hexamethylenetetramine, and DI water. Following that, a PS layer was deposited by spin coating. Finally, the device with a structure of Ti/ PS/ZnO nanorods/FTO was completed by e-gun evaporated Ti layer on top of the PS layer. Semiconductor parameters analyzer Agilent 4156C was then used to measure the I-V characteristics of the device by applying linear ramp sweep voltage with sweep sequence of 0V → 4V → 0V → 3V → 0V → 2V → 0V → 1V → 0V in both positive and negative directions. It is interesting to find that the I-V characteristics are bias dependent and hysteretic, indicating that the device Ti/PS/ZnO nanorods/FTO structure has ferroelectricity. Our results also show that the maximum hysteresis loop height of the I-V characteristics as well as the voltage at which the maximum hysteresis loop height of each scan occurs increase with increasing maximum sweep voltage. It should be noticed that, although ferroelectricity has been found in ZnO at its melting temperature (1975℃) and in Li- or Co-doped ZnO, neither PS nor ZnO has ferroelectricity at room temperature. Using the same structure but with a PS or ZnO layer only as the insulator does not give and hysteretic I-V characteristics. It is believed that a charge polarization layer is induced near the PS/ZnO nanorods stack interface and thus causes the ferroelectricity in the device with Ti/PS/ZnO nanorods/FTO structure. Our results show that the PS/ZnO stack can find a potential application in a resistive switching memory device with MIM structure.

Keywords: ferroelectricity, hysteresis, polystyrene, resistance switching, ZnO nanorods

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Authors: Yih-Chien Chen, Tse-Lung Lin

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The microwave characteristics of NdTi₍₀.₅₋ₓ₎GeₓMo₀.₅O₄ are studied to determine the feasibility of their use in the liquid sensor. The microwave characteristics of NdTi₍₀.₅₋ₓ₎GeₓMo₀.₅O₄ are determined using X-ray diffraction (XRD) patterns. The permittivity (𝜀r) of NdTi₍₀.₄₉₎Ge₀.₀₁Mo₀.₅O₄ that is sintered at 1425 ℃ for 4 h is 17.6, the unloaded quality factor (Qu×f) is 33,400 GHz, and it has a temperature coefficient at the resonance frequency (TCF) of -30.7 ppm/℃. The proposed liquid sensor is at the 5G FR1 bands.

Keywords: NdTi₍₀.₅₋ₓ₎GeₓMo₀.₅O₄, X-ray diffraction pattern, permittivity, Unloaded quality factor

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Authors: Kashan Bashir, Salah Naji Ahmed Sufyan, Mirza Umar Baig

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In this study, n-dodecane, tetralin, decalin, and tetramethybenzene (TMBE) were used as model compounds of alkanes, naphthenic-aromatic, cycloalkanes and alkyl-benzenes presented in hydro-diesel. The catalytic cracking properties of four model compounds over Y zeolite catalyst (Y-Cat.) and ZSM-5 zeolite catalysts (ZSM-5-Cat.) were probed. The experiment results revealed that high conversion of macromolecular paraffin and naphthenic aromatics were achieved over Y-Cat, whereas its low cracking activity of intermediate products micromolecules paraffin and olefin and high activity of hydride transfer reaction goes against the production of value-added products (light olefin and gasoline). In contrast, despite the fact that the hydride transfer reaction was greatly inhabited over ZSM-5-Cat, the low conversion of macromolecules was observed attributed to diffusion limitations. Interestingly, the mixed catalyst compensates for the shortcomings of the two catalysts, and a “relay reaction” between Y-Cat and ZSM-5-Cat was proposed. Specifically, the added Y-Cat acts as a “pre-cracking booster site” and promotes macromolecules conversion. The addition of ZSM-5-Cat not only significantly suppresses the hydride transfer reaction but also contributes to the cracking of immediate products paraffin and olefin into ethylene and propylene, resulting in a high yield of alkyl-benzene (gasoline), ethylene, and propylene with a low yield of naphthalene (LCO) and coke. The catalytic cracking evaluation experiments of mixed hydro-LCO were also performed to further clarify the “relay reaction” above, showing the highest yield of LPG and gasoline over mixed catalyst. The results indicate that the Y-cat and ZSM-5-cat have a synergistic effect on the conversion of hydro-diesel and corresponding value-added product yield and selective coke yield.

Keywords: synergistic effect, hydro-diesel cracking, FCC, zeolite catalyst, ethylene and propylene

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Authors: T. Nakpun, T. Kanjanarach, T. Kittisopee

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Turnover of community pharmacist can affect continuity of patient care and most importantly the quality of care and also the costs of a pharmacy. It was hypothesized that organizational resources, job characteristics, and social supports had direct effect on pharmacist turnover intention, and indirect effect on pharmacist turnover intention via pharmacist engagement. This research aimed to study influencing factors on pharmacist engagement and pharmacist turnover intention by testing the proposed structural hypothesized model to explain the relationship among organizational resources, job characteristics, and social supports that effect on pharmacist turnover intention and pharmacist engagement in Thai community pharmacists. A cross sectional study design with self-administered questionnaire was conducted in 209 Thai community pharmacists. Data were analyzed using Structural Equation Modeling technique with analysis of a moment structures AMOS program. The final model showed that only organizational resources had significant negative direct effect on pharmacist turnover intention (β =-0.45). Job characteristics and social supports had significant positive relationship with pharmacist engagement (β = 0.44, and 0.55 respectively). Pharmacist engagement had significant negative relationship with pharmacist turnover intention (β = - 0.24). Thus, job characteristics and social supports had significant negative indirect effect on turnover intention via pharmacist engagement (β =-0.11 and -0.13, respectively). The model fit the data well (χ2/ degree of freedom (DF) = 2.12, the goodness of fit index (GFI)=0.89, comparative fit index (CFI) = 0.94 and root mean square error of approximation (RMSEA) = 0.07). This study can be concluded that organizational resources were the most important factor because it had direct effect on pharmacist turnover intention. Job characteristics and social supports were also help decrease pharmacist turnover intention via pharmacist engagement.

Keywords: community pharmacist, influencing factor, turnover intention, work engagement

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Authors: A. Q. Ahmed, S. Gao

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In this paper, the energy saving and human thermal comfort in a typical office room are investigated. The impact of a combined system of exhaust inlet air with light slots located at the ceiling level in a room served by displacement ventilation system is numerically modelled. Previous experimental data are used to validate the computational fluid dynamic (CFD) model. A case study of simulated office room includes two seating occupants, two computers, two data loggers and four lamps. The combined system is located at the ceiling level above the heat sources. A new method of calculation for the cooling coil load in stratified air distribution (STRAD) system is used in this study. The results show that 47.4 % energy saving of space cooling load can be achieved by combing the exhaust inlet air with light slots at the ceiling level above the heat sources.

Keywords: air conditioning, displacement ventilation, energy saving, thermal comfort

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Authors: Kang Won Lee, Jung Won Lee

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Characterizing the network flow is of fundamental importance to understand the complex dynamics of networks. And passenger flow characteristics of the subway network are very relevant for an effective transportation management in urban cities. In this study, passenger flow of Seoul metropolitan subway network is investigated and characterized through statistical analysis. Traditional betweenness centrality measure considers only topological structure of the network and ignores the transportation factors. This paper proposes a weighted betweenness centrality measure that incorporates monthly passenger flow volume. We apply the proposed measure on the Seoul metropolitan subway network involving 493 stations and 16 lines. Several interesting insights about the network are derived from the new measures. Using Kolmogorov-Smirnov test, we also find out that monthly passenger flow between any two stations follows a power-law distribution and other traffic characteristics such as congestion level and throughflow traffic follow exponential distribution.

Keywords: betweenness centrality, correlation coefficient, power-law distribution, Korea traffic DB

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Authors: Jantakan Jullawateelert, Korakod Haonoo, Sutipong Sananseang, Sarun Torpaiboon, Thanunthon Bowornsakulwong, Lalintip Hocharoen

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Process scale-up is essential for the biological process to increase production capacity from bench-scale bioreactors to either pilot or commercial production. Scale-up based on constant volumetric oxygen mass transfer coefficient (KLa) is mostly used as a scale-up factor since oxygen supply is one of the key limiting factors for cell growth. However, to estimate KLa of culture vessels operated with different conditions are time-consuming since it is considerably influenced by a lot of factors. To overcome the issue, this study aimed to establish correlation equations of KLa and operating parameters in 0.5 L and 5 L bioreactor employed with pitched-blade impeller and gas sparger. Temperature, gas flow rate, agitation speed, and impeller position were selected as process parameters and equations were created using response surface methodology (RSM) based on central composite design (CCD). In addition, the effects of these parameters on KLa were also investigated. Based on RSM, second-order polynomial models for 0.5 L and 5 L bioreactor were obtained with an acceptable determination coefficient (R²) as 0.9736 and 0.9190, respectively. These models were validated, and experimental values showed differences less than 10% from the predicted values. Moreover, RSM revealed that gas flow rate is the most significant parameter while temperature and agitation speed were also found to greatly affect the KLa in both bioreactors. Nevertheless, impeller position was shown to influence KLa in only 5L system. To sum up, these modeled correlations can be used to accurately predict KLa within the specified range of process parameters of two different sizes of bioreactors for further scale-up application.

Keywords: response surface methodology, scale-up, stirred-tank bioreactor, volumetric oxygen mass transfer coefficient

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Authors: Florent Cerdan, Anne-Gaëlle Denay, Annette Roy, Jean-Claude Grandidier, Éric Laine

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The insulation of MarkIII membrane of the Liquid Natural Gas Carriers (LNGC) consists of a load- bearing system made of panels in reinforced polyurethane foam (R-PUF). During the shipping, the cargo containment shall be potentially subject to risk events which can be water leakage through the wall ballast tank. The aim of these present works is to further develop understanding of water transfer mechanisms and water effect on properties of R-PUF. This multi-scale approach contributes to improve the durability. Macroscale / Mesoscale Firstly, the use of the gravimetric technique has allowed to define, at room temperature, the water transfer mechanisms and kinetic diffusion, in the R-PUF. The solubility follows a first kinetic fast growing connected to the water absorption by the micro-porosity, and then evolves linearly slowly, this second stage is connected to molecular diffusion and dissolution of water in the dense membranes polyurethane. Secondly, in the purpose of improving the understanding of the transfer mechanism, the study of the evolution of the buoyant force has been established. It allowed to identify the effect of the balance of total and partial pressure of mixture gas contained in pores surface. Mesoscale / Microscale The differential scanning calorimetry (DSC) and Dynamical Mechanical Analysis (DMA), have been used to investigate the hydration of the hard and soft segments of the polyurethane matrix. The purpose was to identify the sensitivity of these two phases. It been shown that the glass transition temperatures shifts towards the low temperatures when the solubility of the water increases. These observations permit to conclude to a plasticization of the polymer matrix. Microscale The Fourier Transform Infrared (FTIR) study has been used to investigate the characterization of functional groups on the edge, the center and mid-way of the sample according the duration of submersion. More water there is in the material, more the water fix themselves on the urethanes groups and more specifically on amide groups. The pic of C=O urethane shifts at lower frequencies quickly before 24 hours of submersion then grows slowly. The intensity of the pic decreases more flatly after that.

Keywords: porous materials, water sorption, glass transition temperature, DSC, DMA, FTIR, transfer mechanisms

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Authors: Mahmood Seyyed, Akram Salehi Heykoei, Hamidreza Safakish Kashani

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Among the remaining resource of the past, coins considered as an authentic documents among the most important documentary sources. The coins were minted in a place that called mint. The number and position of the mints in each period reflects the amount of economic power, political security and business growth, which was always fluctuated its position with changing the political and economic condition. Considering that, trade has more growth during the Safavid period than previous ones, the mint also has been in greater importance. It seems the one hand, the growth of economic in Safavid period has a direct link with the number and places of the mints at that time and in the other hand, the mints have been formed in some places because of the specific characteristic of cities and regions. Increasing the number of mints in the north of the country due to the growth of silk trade and in the west and northwest due to the political and commercial relation with Ottoman Empire, also the characteristics such as existence of mines, located in the Silk Road and communication ways, all are the results of this investigation. Accordingly, in this article researcher tries to examine the characteristics that give priority to a city for having mint. With considering that in the various historical periods, the mints were based in the most important cities in terms of political and social, at that time, this article examines the cities specific characteristics in the formation of the mints in Safavid period.

Keywords: documentary sources, coins, mint, city, Safavid

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Authors: Olga Yu Kurapova, Alexander V. Shorokhov, Vladimir G. Konakov

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Nowadays, due to their exceptional anion conductivity at high temperatures cubic zirconia solid solutions, stabilized by rare-earth and alkaline-earth metal oxides, are widely used as a solid electrolyte (SE) materials in different electrochemical devices such as gas sensors, oxygen pumps, solid oxide fuel cells (SOFC), etc. Nowadays the intensive studies are carried out in a field of novel fully stabilized zirconia based SE development. The use of precursor powders for SE manufacturing allows predetermining the microstructure, electrical and sensor characteristics of zirconia based ceramics used as SE. Thus the goal of the present work was the investigation of the effect of precursor powder size on the electrical and sensor characteristics of fully stabilized zirconia-based solid electrolytes with compositions of 0,08Y2O3∙0,92ZrO2 (YSZ), 0,06Ce2O3∙ 0,06Y2O3∙0,88ZrO2 and 0,09Ce2O3∙0,06Y2O3-0,85ZrO2. The synthesis of precursors powders with different mean particle size was performed by sol-gel synthesis in the form of reversed co-precipitation from aqueous solutions. The cakes were washed until the neutral pH and pan-dried at 110 °С. Also, YSZ ceramics was obtained by conventional solid state synthesis including milling into a planetary mill. Then the powder was cold pressed into the pellets with a diameter of 7.2 and ~4 mm thickness at P ~16 kg/cm2 and then hydrostatically pressed. The pellets were annealed at 1600 °С for 2 hours. The phase composition of as-synthesized SE was investigated by X-Ray photoelectron spectroscopy ESCA (spectrometer ESCA-5400, PHI) X-ray diffraction analysis - XRD (Shimadzu XRD-6000). Following galvanic cell О2 (РО2(1)), Pt | SE | Pt, (РО2(2) = 0.21 atm) was used for SE sensor properties investigation. The value of РО2(1) was set by mixing of O2 and N2 in the defined proportions with the accuracy of  5%. The temperature was measured by Pt/Pt-10% Rh thermocouple, The cell electromotive force (EMF) measurement was carried out with ± 0.1 mV accuracy. During the operation at the constant temperature, reproducibility was better than 5 mV. Asymmetric potential measured for all SE appeared to be negligible. It was shown that the resistivity of YSZ ceramics decreases in about two times upon the mean agglomerates decrease from 200-250 to 40 nm. It is likely due to the both surface and bulk resistivity decrease in grains. So the overall decrease of grain size in ceramic SE results in the significant decrease of the total ceramics resistivity allowing sensor operation at lower temperatures. For the SE manufactured the estimation of oxygen ion transfer number tion was carried out in the range 600-800 °С. YSZ ceramics manufactured from powders with the mean particle size 40-140 nm, shows the highest values i.e. 0.97-0.98. SE manufactured from precursors with the mean particle size 40-140 nm shows higher sensor characteristic i.e. temperature and oxygen concentration EMF dependencies, EMF (ENernst - Ereal), tion, response time, then ceramics, manufactured by conventional solid state synthesis.

Keywords: oxygen sensors, precursor powders, sol-gel synthesis, stabilized zirconia ceramics

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Authors: Yacine Babou, Nitesh Ranjan, Branimir Radisavljevic , Martin Seeger, Daniel Over, Torsten Votteler, Bernardo Galletti, Paulo Cristini

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In the frame of replacement of Sulfur hexafluoride (SF6) gas as insulating and switching medium, diverse alternative gases, offering acceptable Global Warming Potential and fulfilling requirements in terms of heat dissipation, insulation and arc quenching performances are currently investigated for High Voltage Circuit Breaker applications. Among the potential gases, CO₂ seems a promising candidate for replacing SF6, because on one hand it is environmentally friendly, harmless, non-toxic, non-corrosive, non-flammable and on the other hand previous studies have demonstrated its fair interruption capabilities. The present study aims at investigating the performance of CO₂ for the thermal interruption in high voltage self-blast circuit breakers. In particular, the correlation between thermal interruption performance and arc voltage is considered and the effect of the arc-network interaction on the performance is rigorously analyzed. For the considered designs, the thermal interruption was evaluated by varying the slope at current zero (i.e., di/dt) for which the breaker could interrupt. Besides, the characteristics of the post-arc current are examined in detail for various rated voltages and currents. The outcome of these experimental investigations will be reported and analyzed.

Keywords: current zero measurement, high voltage circuit breaker, thermal arc discharge, thermal interruption

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Authors: A. A. Abdullah, K. A. Lindsay

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The management of a salt-gradient is investigated with respect to the interaction between the solar pond and its associated evaporation pond. Issues considered are the impact of precipitation and the operation of the flushing system with particular reference to the case in which the flushing fluid is pure water. Results suggest that a management strategy based on a flushing system that simply replaces evaporation losses of water from the solar pond and evaporation pond will be optimally efficient. Such a management strategy will maintain the operational viability of a salt-gradient solar pond as a reservoir of cheap heat while simultaneously ensuring that the associated evaporation pond can feed the storage zone of the solar pond with sufficient saturated brine to balance the effect of salt diffusion. Other findings are, first, that once near saturation is achieved in the evaporation pond, the efficacy of the proposed management strategy is relatively insensitive to both the size of the evaporation pond or its depth, and second, small changes in the extraction of heat from the storage zone of a salt-gradient solar pond have an amplified effect on the temperature of that zone. The possibility of boiling of the storage zone cannot be ignored in a well-configured salt-gradient solar pond.

Keywords: aqueous sodium chloride, constitutive expression, solar pond, salt-gradient

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Authors: N. Yaiphaba, Elizabeth C. H.

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YPO₄ nanoparticles codoped with Eu³⁺(5 at.%) and Bi³⁺(0, 1, 3, 5, 7, 10, 12, 15, 20 at.%) have been prepared in poly acrylic acid (PAA)-H₂O medium by hydrothermal synthesis by maintaining a temperature of 180oC. The crystalline structure of as-prepared and 500oC annealed samples transforms from tetragonal (JCPDS-11-0254) to hexagonal phase (JCPDS-42-0082) with increasing concentration of Bi³⁺ ions. However, 900oC annealed samples exhibit tetragonal structure. The crystallite size of the particles varies from 19-50 nm. The luminescence intensity increases at lower concentration of Bi³⁺ ions and then decreases with increasing Bi3+ ion concentrations. The luminescence intensity further increases on annealing at 500oC and 900oC. Further, 900oC annealed samples show sharp increase in luminescence intensity. Moreover, the samples follow bi-exponential decay indicating energy transfer from donor to the activator or non-uniform distribution of ions in the samples. The samples on excitation at 318 nm exhibit near white emission while at 394 nm excitation show emission in the red region. The as-prepared samples are redispersible and have potential applications in display devices, metal ion sensing, biological labelling, etc.

Keywords: charge transfer, sensitizer, activator, annealing

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Authors: Mousa Meratizaman, Sina Monadizadeh, Majid Amidpour

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One of the most favorable thermal desalination methods used widely today is Multi Effect Desalination. High energy consumption in this method causes coupling it with high temperature power cycle like gas turbine. This combination leads to higher energy efficiency. One of the high temperature power systems which have cogeneration opportunities is Solid Oxide Fuel Cell / Gas Turbine. Integration of Multi Effect Desalination with Solid Oxide Fuel Cell /Gas Turbine power cycle in a range of 300-1000 kW is considered in this article. The exhausted heat of Solid Oxide Fuel Cell /Gas Turbine power cycle is used in Heat Recovery Steam Generator to produce needed motive steam for Desalination unit. Thermodynamic simulation and parametric studies of proposed system are carried out to investigate the system performance.

Keywords: solid oxide fuel cell, thermodynamic simulation, multi effect desalination, gas turbine hybrid cycle

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Authors: Marinka K. Baghdasaryan, Siranush M. Muradyan, Avgen A. Gasparyan

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Analytical expressions of the current and angular errors, as well as the frequency characteristics of an induction converter describing the relation with its structural parameters, the core and winding characteristics are obtained. Based on estimation of the dependences obtained, a mathematical problem of parametric optimization is formulated which can successfully be used for investigation and diagnosing an induction converter.

Keywords: induction converters, magnetic circuit material, current and angular errors, frequency response, mathematical formulation, structural parameters

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Authors: Yubo Bi, Xiao Chen, Shouxiang Lu

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A kind of gas-fueled burner, named Burning Rate Emulator, was proposed for the purpose of the emulation of condensed fuel recently. The gaseous fuel can be pure combustible fuel gas or blends of gaseous fuel or inert gas. However, this concept was recently proposed without detailed study on the combustion characteristic of fuel blends. In this study, two kinds of common gaseous fuels were selected, propane and acetylene, to provide the combustion heat as well as a large amount of smoke, which widely exists in liquid and solid fuel burning process. A set of experiments were carried out using a gas-fueled burner with a diameter of 8 cm. The total volume flow rate of propane and acetylene was kept at 3 liters per minute. The volume fraction of propane varied from 0% to 100% at interval of 10%. It is found that the flame height increases with propane volume fraction, which may be caused by the increase of heat release rate, as the energy density of propane is larger than that of acetylene. The dimensionless flame height is correlated against dimensionless heat release rate, which shows a power function relationship. The radiation fraction of the flame does not show a monotonic relationship with propane volume fraction. With the increase of propane volume fraction from 0% to 100%, the value of radiation fraction increases first and reach a maximum value around 0.46 at a propane volume fraction of 10%, and then decreases continuously to a value of 0.25 at the propane volume fraction of 100%. The flame radiation is related to the soot in the flame. The trend of the radiation fraction reflects that there may be a synergistic effect of soot formation between propane and acetylene which can be guessed from the significantly high radiation fraction at a propane volume fraction of 10%. This work provides data for combustion of gaseous fuel blends pool fire and also give reference on the design of Burning Rate Emulator.

Keywords: Burning Rate Emulator, fuel blends pool fire, flame height, radiation fraction

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Authors: Hafiz Husnain Nawaz

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Anthracnose disease in olive, caused by the fungal pathogen Colletotrichum acutatum, is considered one of the most critical issues in olive orchards in Pakistan. This disease poses a significant threat as it results in infections that can lead to the complete damage of olive plants, affecting leaves, stems, and fruits in the field. Controlling this disease is particularly challenging due to the absence of an effective fungicide that does not pose risks to farmer health and the environment. To address this challenge, our study aimed to evaluate the antagonistic activity of a biosurfactant produced by the Bacillus subtilis PE-07 strain against the anthracnose-causing agent in olive plants. This strain was selected after screening sixty rhizobacteria strains. Additionally, we assessed the heat stability, pH range, and toxicity of the biosurfactant produced by strain PE-07. Our results revealed that the biosurfactant exhibited maximum antifungal activity against C. acutatum. In vitro studies indicated that the biosurfactant could reduce fungal activity by inhibiting the spore germination of C. acutatum. Furthermore, the biosurfactant demonstrated a wide pH and temperature range, displaying antifungal activity at pH levels ranging from 5 to 10 and a temperature range from room temperature to 110°C. To evaluate the biosurfactant's safety, we conducted toxicity tests on zebra fish (Danio rerio). The results showed that the biosurfactant had minimal harmful effects, even at maximum concentrations. In conclusion, our study confirmed that the biosurfactant produced by B. subtilis exhibited high pH and heat stability with minimal harmful effects. Therefore, it presents a promising alternative to chemical pesticides for effectively controlling olive anthracnose in Pakistan.

Keywords: biological control, heat stability and PH range, toxicity, Danio rerio

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Authors: S. Badrinarayanan, R. Vimal, H. Sivaraman, P. Deepak, R. Vignesh Kumar, A. Ponshanmugakumar

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In the present study, the flammability properties of banana fibre reinforced epoxy/ sodium bromate blended composites are studied. Two sets of composite material were prepared, one formed by blending sodium bromate with epoxy matrix and other with neat epoxy matrix. Epoxy resin was blended with various weight fractions of sodium bromate, 4%, 8% and 12%. The composite made with plain epoxy matrix was used as the standard reference material. The mechanical tests, heat deflection tests and flammability tests were carried out on all the composite samples. Flammability test shows the improved flammability properties of the sodium bromated banana-epoxy composite. The modification in flammability properties of the composites by the addition of sodium bromate results in the reduced mechanical properties. The fractured surfaces under various mechanical testing were analysed using morphological analysis done using scanning electron microscope.

Keywords: banana fibres, epoxy resin, sodium bromate, flammability test, heat deflection

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Authors: N. Hatraf, L. Merabti, Z. Neffah, W. Taane

Abstract:

The excessive consumption of fossil energies (electrical energy) during summer caused by the technological development involves more and more climate warming. In order to reduce the worst impact of gas emissions produced from classical air conditioning, heat driven solar absorption chiller is pretty promising; it consists on using solar as motive energy which is clean and environmentally friendly to provide cold. Solar absorption machine is composed by four components using Lithium Bromide /water as a refrigerating couple. LiBr- water is the most promising in chiller applications due to high safety, high volatility ratio, high affinity, high stability and its high latent heat. The lithium bromide solution is constitute by the salt lithium bromide which absorbs water under certain conditions of pressure and temperature however if the concentration of the solution is high in the absorption chillers; which exceed 70%, the solution will crystallize. The main aim of this article is to study the phenomena of the crystallization and to evaluate how the dependence between the electric conductivity and the concentration which should be controlled.

Keywords: absorption, crystallization, experimental results, lithium bromide solution

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Authors: Moulay Smaïne Ghembaza, Mokhtar Dadouch, Nour-Said Ikhlef

Abstract:

Soil treatment is to make use soil that does not have the characteristics required in a given context. We limit ourselves in this work to the field of road earthworks where we have chosen to develop a local material in the region of Sidi Bel Abbes (Algeria). This material has poor characteristics not meeting the standards used in road geo technics. To remedy this, firstly, we were trying to improve the Proctor Standard characteristics of this material by mechanical treatment increasing the compaction energy. Then, by a chemical treatment, adding some cement dosages, our results show that this material classified A1h a increase maximum dry density and a reduction in the water content of compaction. A comparative study is made on the optimal properties of the material between the two modes of treatment. On the other hand, after treatment, one finds a decrease in the plasticity index and the methylene blue value. This material exhibits a change of class. Therefore, soil class CL turned into a soil class composed CL-ML (Silt of low plasticity). This observation allows this material to be used as backfill or sub grade.

Keywords: treatment of soil, cement, subgrade, Atteberg limits, classification, optimum proctor properties

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Authors: H. Feza Carlak, N. G. Gencer

Abstract:

To increase the temperature contrast in thermal images, the characteristics of the electrical conductivity and thermal imaging modalities can be combined. In this experimental study, it is objected to observe whether the temperature contrast created by the tumor tissue can be improved just due to the current application within medical safety limits. Various thermal breast phantoms are developed to simulate the female breast tissue. In vitro experiments are implemented using a thermal infrared camera in a controlled manner. Since experiments are implemented in vitro, there is no metabolic heat generation and blood perfusion. Only the effects and results of the electrical stimulation are investigated. Experimental study is implemented with two-dimensional models. Temperature contrasts due to the tumor tissues are obtained. Cancerous tissue is determined using the difference and ratio of healthy and tumor images. 1 cm diameter single tumor tissue causes almost 40 °mC temperature contrast on the thermal-breast phantom. Electrode artifacts are reduced by taking the difference and ratio of background (healthy) and tumor images. Ratio of healthy and tumor images show that temperature contrast is increased by the current application.

Keywords: medical diagnostic imaging, breast phantom, active thermography, breast cancer detection

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Authors: Marta Cordero-Gracia, Mariola Gomez, Olivier Blesbois, Marina Carrion

Abstract:

One of the difficulties in icing simulations is for extended periods of exposure, when very large ice shapes are created. As well as being large, they can have complex shapes, such as a double horn. For icing simulations, these configurations are currently computed in several steps. The icing step is stopped when the ice shapes become too large, at which point a new mesh has to be created to allow for further CFD and ice growth simulations to be performed. This can be very costly, and is a limiting factor in the simulations that can be performed. A way to avoid the costly human intervention in the re-meshing step of multistep icing computation is to use mesh deformation instead of re-meshing. The aim of the present work is to apply an interpolation method based on Radial Basis Functions (RBF) to transfer deformations from surface mesh to volume mesh. This deformation tool has been developed specifically for icing problems. It is able to deal with localized, sharp and large deformations, unlike the tools traditionally used for more smooth wing deformations. This tool will be presented along with validation on typical two-dimensional icing shapes.

Keywords: ice accretion, interpolation, mesh deformation, radial basis functions

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Authors: Jorge Gonzalez Camus, Valentin Keyantuo, Mahamadi Warma

Abstract:

In this work, we obtain representation results for solutions of a time-fractional differential equation involving the discrete fractional Laplace operator in terms of generalized Wright functions. Such equations arise in the modeling of many physical systems, for example, chain processes in chemistry and radioactivity. The focus is on the linear problem of the simplified Moore - Gibson - Thompson equation, where the discrete fractional Laplacian and the Caputo fractional derivate of order on (0,2] are involved. As a particular case, we obtain the explicit solution for the discrete heat equation and discrete wave equation. Furthermore, we show the explicit solution for the equation involving the perturbed Laplacian by the identity operator. The main tool for obtaining the explicit solution are the Laplace and discrete Fourier transforms, and Stirling's formula. The methodology mainly is to apply both transforms in the equation, to find the inverse of each transform, and to prove that this solution is well defined, using Stirling´s formula.

Keywords: discrete fractional Laplacian, explicit representation of solutions, fractional heat and wave equations, fundamental

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Authors: Adnan I. O. Zaid, Safwan M. A. Alqawabah

Abstract:

Review of the available literature on grain refinement of aluminum and its alloys reveals that little work is published on the effect of refiners on mechanical characteristics and wear resistance. In this paper, the effect of addition of Zr to Al grain refined by Ti+B on its metallurgical, mechanical characteristics and wear resistance both in the as cast and after extrusion condition are presented and discussed. It was found that Addition of Zr to Al resulted in deterioration of its mechanical strength and hardness, whereas it resulted in improvement of both of them when added to Al grain refined by Ti+B. Furthermore it was found that the direct extrusion process resulted in further increase of the mechanical strength and hardness of Al and its micro-alloys. Also it resulted in increase of their work hardening index, n, i.e. improved their formability, hence it reduces the number of stages required for forming at large strains in excess of the plastic instability before Zr addition.

Keywords: aluminum, grain refinement, titanium + boron, zirconium, mechanical characteristics, wear resistance, direct extrusion

Procedia PDF Downloads 446

Authors: Peng Zhang, Cai Liang

Abstract:

The non-biodegradable plastic wastes have posed severe environmental and ecological contaminations. Numerous technologies, such as pyrolysis, incineration, and landfilling, have already been employed for the treatment of plastic waste. Compared with conventional methods, microwave has displayed unique advantages in the rapid production of hydrogen from plastic wastes. Understanding the interaction between microwave radiation and materials would promote the optimization of several parameters for the microwave reaction system. In this work, various carbon materials have been investigated to reveal microwave heating performance and the ensuing catalytic activity. Results showed that the diversity in the heating characteristic was mainly due to the dielectric properties and the individual microstructures. Furthermore, the gaps and steps among the surface of carbon materials would lead to the distortion of the electromagnetic field, which correspondingly induced plasma discharging. The intensity and location of local plasma were also studied. For high-yield H₂ production, iron nanoparticles were selected as the active sites, and a series of iron/carbon bifunctional catalysts were synthesized. Apart from the high catalytic activity, the iron particles in nano-size close to the microwave skin depth would transfer microwave irradiation to the heat, intensifying the decomposition of plastics. Under microwave radiation, iron is supported on activated carbon material with 10wt.% loading exhibited the best catalytic activity for H₂ production. Specifically, the plastics were rapidly heated up and subsequently converted into H₂ with a hydrogen efficiency of 85%. This work demonstrated a deep understanding of microwave reaction systems and provided the optimization for plastic treatment.

Keywords: plastic waste, recycling, hydrogen, microwave

Procedia PDF Downloads 71