Search results for: Black Aluminum Oxide

Authors: N. Tugrul, A. S. Kipcak, N. Baran Acarali, E. Moroydor Derun, S. Piskin

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Magnesium borate(MB) istechnical ceramic for high heat-resisting, corrosion-resisting, super mechanical strength, superinsulation, light weight, high strength, and high coefficient of elasticity. Zinc borate (ZB) can be used as multi-functional synergistic additives with flame retardant additives in polymers. The most important properties are low solubility in water and high dehydration temperature. ZB dehydrates above 290°C and anhydrous ZB has thermal resistance about 400°C. In this study, the raw materials of ZnO, MgO and H₃BO₃ were used with mole ratio of 1:1:9. With the starting materials hydrothermal method was applied at a temperature of 100^oC. The reaction time was determined as 30, 60, 90 and 120 minutes after some preliminary experiments. After the synthesis, the crystal structure and the morphology of the products were examined by X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR). As a result, the forms of Zinc Oxide Borate Hydrate [Zn₃B₆O₁₂.3.5H₂O], Admontite [MgO(B₂O₃)₃.7(H₂O)] and Mcallisterite [Mg₂(B₆O₇(OH)₆)₂.9(H₂O)] were synthesized.

Keywords: Magnesium borate, zinc borate, XRD, FT-IR.

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Authors: Chundong Li, V. V. Neshchimenko, M. M. Mikhailov

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The effect of the modification of ZnO powders by ZrO₂, Al₂O₃, TiO₂, SiO₂, CeO₂ and Y₂O₃ nanoparticles with a concentration of 1-30 wt % is investigated by diffuse reflectance spectra within the wavelength range 200 to 2500 nm before and after 100 keV proton and electron irradiation. It has been established that the introduction of nanoparticles ZrO₂, Al₂O₃ enhances the optical stability of the pigments under proton irradiation, but reduces it under electron irradiation. Modifying with TiO₂, SiO₂, CeO₂, Y₂O₃ nanopowders leads to decrease radiation stability in both types of irradiation. Samples modified by 5 wt. % of ZrO₂ nanoparticles have the highest stability of optical properties after proton exposure. The degradation of optical properties under electron irradiation is not high for this concentration of nanoparticles. A decrease in the absorption of pigments modified with nanoparticles proton exposure is determined by a decrease in the intensity of bands located in the UV and visible regions. After electron exposure the absorption bands have in the whole spectrum range.

Keywords: Irradiation, nanopowders, radiation stability, zinc oxide.

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Authors: Adeosun S. Oluropo, Sekunowo O. Israel, Talabi S. Isaac

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This study investigated the combined effect of cold rolling and heat treatment on the mechanical properties of Al-Ti alloy. Samples of the alloy are cast in metal mould to obtain 0.94-2.19wt% mixes of titanium. These samples are grouped into untreated (as-cast) and those that are cold rolled to fifty percent reduction, homogenized at 500⁰C and soaked for one hour. The cold rolled and heat treated samples are normalized (RT_n) and quench-tempered (RT_q-t) at 100⁰C. All these samples are subjected to tensile, micro-hardness and microstructural evaluation. Results show remarkable improvement in the mechanical properties of the cold rolled and heat treated samples compared to the as-cast. In particular, the RT_q-t samples containing titanium in the range of 1.7-2.2% demonstrates improve tensile strength by 24.7%, yield strength, 28%, elastic modulus, 38.3% and micro-hardness, 20.5%. The Al₃Ti phase being the most stable precipitate in the α-Al matrix appears to have been responsible for the significant improvement in the alloy’s mechanical properties. It is concluded that quench and temper heat treatment is an effective method of improving the strength-strain ratio of cold rolled Al-.0.9-2.2%Ti alloy.

Keywords: Aluminum-titanium alloy, heat treatment, mechanical properties, precipitate.

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Authors: Hai-Qing Xie, Yun Zeng, Yong-Hong Yan, Jian-Ping Zeng, Tai-Hong Wang

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Photo-BJMOSFET (Bipolar Junction Metal-Oxide- Semiconductor Field Effect Transistor) fabricated on SOI film was proposed. ITO film is adopted in the device as gate electrode to reduce light absorption. Depletion region but not inversion region is formed in film by applying gate voltage (but low reverse voltage) to achieve high photo-to-dark-current ratio. Comparisons of photoelectriccharacteristics executed among VGK=0V, 0.3V, 0.6V, 0.9V and 1.0V (reverse voltage VAK is equal to 1.0V for total area of 10×10μm2). The results indicate that the greatest improvement in photo-to-dark-current ratio is achieved up to 2.38 at VGK=0.6V. In addition, photo-BJMOSFET is compatible with CMOS integration due to big input resistance

Keywords: Photo-BJMOSFET, Responsivity, Sensitivity, Spectral response.

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Authors: A.Guntida, K. Suriye, S. Kunjara Na Ayudhya, J. Panpranot, P. Praserthdam

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Propylene self-metathesis to ethylene and butene was studied over WOx/SiO2 catalysts at 450oC and atmospheric pressure. The WOx/SiO2 catalysts were prepared by incipient wetness impregnation of ammonium metatungstate aqueous solution. It was found that, adding nano-sized extra supports (SiO2 and TiO2) by physical mixing with the WOx/SiO2 enhanced propylene conversion. The UV-Vis and FT-Raman results revealed that WOx could migrate from the original silica support to the extra support, leading to a better dispersion of WOx. The ICP-OES results also indicate that WOx existed on the extra support. Coke formation was investigated on the catalysts after 10 h time-on-stream by TPO. However, adding nano-sized extra supports led to higher coke formation which may be related to acidity as characterized by NH3-TPD.

Keywords: Extra support, nanomaterial, propylene self-metathesis, tungsten oxide.

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Authors: Gizem Kodak

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The Strait of Çanakkale (Dardanelles), together with the Strait of Istanbul and the Sea of Marmara, form the Turkish Straits System. In other words, the Strait of Çanakkale is the southern gate of the system that connects the Black Sea countries with the other countries of the world. Due to the heavy maritime traffic, it is important to scientifically examine the accident characteristics in the region. In particular, the results indicated by the descriptive statistics are of critical importance in order to strengthen the safety of navigation. At this point, exploratory data analysis offers strategic outputs in terms of defining the problem and knowing the strengths and weaknesses against possible accident risk. The study aims to determine the accident characteristics in the Strait of Çanakkale with temporal and spatial analysis of historical data, using Exploratory Data Analysis (EDA) as the research method. The study's results will reveal the general characteristics of maritime accidents in the region and form the infrastructure for future studies. Therefore, the text provides a clear description of the research goals and methodology, and the study's contributions are well-defined.

Keywords: Maritime Accidents, EDA, Strait of Çanakkale, navigational safety.

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Authors: M. Invigorito, G. Elia, M. Panelli

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Hybrid propulsion combines beneficial properties of both solid and liquid rockets, such as multiple restarts, throttability as well as simplicity and reduced costs. A nitrous oxide (N₂O)/paraffin-based hybrid rocket engine demonstrator is currently under development at the Italian Aerospace Research Center (CIRA) within the national research program HYPROB, funded by the Italian Ministry of Research. Nitrous oxide belongs to the class of self-pressurizing propellants that exhibit a high vapor pressure at standard ambient temperature. This peculiar feature makes those fluids very attractive for space rocket applications because it avoids the use of complex pressurization systems, leading to great benefits in terms of weight savings and reliability. To avoid feed-system-coupled instabilities, the phase change is required to occur through the injectors. In this regard, the oxidizer is stored in liquid condition while target chamber pressures are designed to lie below vapor pressure. The consequent cavitation and flash vaporization constitute a remarkably complex phenomenology that arises great modelling challenges. Thus, it is clear that the design of the injection system is fundamental for the full exploitation of hybrid rocket engine throttability. The Analytical Hierarchy Process has been used to select the injection architecture as best compromise among different design criteria such as functionality, technology innovation and cost. The impossibility to use engineering simplified relations for the dimensioning of the injectors led to the needs of applying a numerical approach based on OpenFOAM^®. The numerical tool has been validated with selected experimental data from literature. Quantitative, as well as qualitative comparisons are performed in terms of mass flow rate and pressure drop across the injector for several operating conditions. The results show satisfactory agreement with the experimental data. Modeling assumptions, together with their impact on numerical predictions are discussed in the paper. Once assessed the reliability of the numerical tool, the injection plate has been designed and sized to guarantee the required amount of oxidizer in the combustion chamber and therefore to assure high combustion efficiency. To this purpose, the plate has been designed with multiple injectors whose number and diameter have been selected in order to reach the requested mass flow rate for the two operating conditions of maximum and minimum thrust. The overall design has been finally verified through three-dimensional computations in cavitating non-reacting conditions and it has been verified that the proposed design solution is able to guarantee the requested values of mass flow rates.

Keywords: Hybrid rocket, injection system design, OpenFOAM®, cavitation

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Authors: D. S. Mohale, A. V. Chandewar

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Aim- Study was undertaken to investigate the effect of altered behavioral condition like depression on various oxidative stress markers and biochemical parameters in rats. Methods- Rats were subjected for short (21 days) and long term (84 days) social isolation; the rats displayed an increase in depression on force swim test relative to control. Various markers of oxidative stress like lipid per oxidation (LPO), reduced glutathione (GSH), Supers oxide dismutase (SOD), catalase (CAT) and biochemical parameters like SGOT, SGPT, and blood glucose were determined. Results- There was significant increase in the level of LPO and decrease in the levels of GSH, SOD and CAT after long term isolation. Biochemical parameters were significantly altered after social isolation. Conclusion- Increased oxidative stress in depression which may leads to alteration of biochemical parameters.

Keywords: Depression, Glucose, LPO, Oxidative stress.

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Authors: P Chockalingam, K Kok, R Vijayaram

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This paper presents a comparative study on dry and wet grinding through experimental investigation in the grinding of CSM glass fibre reinforced polymer laminates using a pink aluminium oxide wheel. Different sets of experiments were performed to study the effects of the independent grinding parameters such as grinding wheel speed, feed and depth of cut on dependent performance criteria such as cutting forces and surface finish. Experimental conditions were laid out using design of experiment central composite design. An effective coolant was sought in this study to minimise cutting forces and surface roughness for GFRP laminates grinding. Test results showed that the use of coolants reduces surface roughness, although not necessarily the cutting forces. These research findings provide useful economic machining solution in terms of optimized grinding conditions for grinding CSM GFRP.

Keywords: Chopped Strand Mat GFRP laminates, Dry and Wet Grinding, Cutting Forces, Surface Finish.

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Authors: B. Dikici, I. Ozdemir, M. Topuz

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The corrosion behaviour of 316L stainless steel coatings obtained by cold spray method was investigated in this study. 316L powders were deposited onto Al5052 aluminum substrates. The coatings were produced using nitrogen (N₂) process gas. In order to further improve the corrosion and mechanical properties of the coatings, heat treatment was applied at 250 and 750 °C. The corrosion performances of the coatings were compared using the potentiodynamic scanning (PDS) technique under in-vitro conditions (in Ringer’s solution at 37 °C). In addition, the hardness and porosity tests were carried out on the coatings. Microstructural characterization of the coatings was carried out by using scanning electron microscopy attached with energy dispersive spectrometer (SEM-EDS) and X-ray diffraction (XRD) technique. It was found that clean surfaces and a good adhesion were achieved for particle/substrate bonding. The heat treatment process provided both elimination of the anisotropy in the coating and resulting in healing-up of the incomplete interfaces between the deposited particles. It was found that the corrosion potential of the annealed coatings at 750 °C was higher than that of commercially 316 L stainless steel. Moreover, the microstructural investigations after the corrosion tests revealed that corrosion preferentially starts at inter-splat boundaries.

Keywords: 316L, biomaterials, cold spray, heat treatment.

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Authors: B. Bina, M.H. Mehdinejad, Gunnel Dalhammer, Guna RajaraoM. Nikaeen, H. Movahedian Attar

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Coagulation of water involves the use of coagulating agents to bring the suspended matter in the raw water together for settling and the filtration stage. Present study is aimed to examine the effects of aluminum sulfate as coagulant in conjunction with Moringa Oleifera Coagulant Protein as coagulant aid on turbidity, hardness, and bacteria in turbid water. A conventional jar test apparatus was employed for the tests. The best removal was observed at a pH of 7 to 7.5 for all turbidities. Turbidity removal efficiency was resulted between % 80 to % 99 by Moringa Oleifera Coagulant Protein as coagulant aid. Dosage of coagulant and coagulant aid decreased with increasing turbidity. In addition, Moringa Oleifera Coagulant Protein significantly has reduced the required dosage of primary coagulant. Residual Al+3 in treated water were less than 0.2 mg/l and meets the environmental protection agency guidelines. The results showed that turbidity reduction of % 85.9- % 98 paralleled by a primary Escherichia coli reduction of 1-3 log units (99.2 – 99.97%) was obtained within the first 1 to 2 h of treatment. In conclusions, Moringa Oleifera Coagulant Protein as coagulant aid can be used for drinking water treatment without the risk of organic or nutrient release. We demonstrated that optimal design method is an efficient approach for optimization of coagulation-flocculation process and appropriate for raw water treatment.

Keywords: MOCP, Coagulant aid, turbidity removal, E.coliremoval, water, treatment

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Authors: S. S. Pati, L. Herojit Singh, A. C. Oliveira, V. K. Garg

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Chitosan functionalized Fe3O4-Au core shell nanoparticles have been prepared using a two-step wet chemical approach using NaBH4 as reducing agent for formation of Au in ethylene glycol. X-ray diffraction studies shows individual phases of Fe3O4 and Au in the as prepared samples with crystallite size of 5.9 and 11.4 nm respectively. The functionalization of the core-shell nanostructure with Chitosan has been confirmed using Fourier transform infrared spectroscopy along with signatures of octahedral and tetrahedral sites of Fe3O4 below 600cm-1. Mössbauer spectroscopy shows decrease in particle-particle interaction in presence of Au shell (72% sextet) than pure oleic coated Fe3O4 nanoparticles (88% sextet) at room temperature. At 80K, oleic acid coated Fe3O4 shows only sextets whereas the Chitosan functionalized Fe3O4 and Chitosan functionalized Fe3O4@Au core shell show presence of 5 and 11% doublet, respectively.

Keywords: Magnetic nanoparticles, Fe3O4@Au core shell, iron oxide, Au nanoparticles.

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Authors: Hardik Vaghela, Mamta Khosla, Balwindar Raj

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In this paper, we present and investigate a double gate PN diode based tunnel field effect transistor (DGPNTFET). The importance of proposed structure is that the formation of different drain doping is not required and ambipolar effect in OFF state is completely removed for this structure. Validation of this structure to behave like a Tunnel Field Effect Transistor (TFET) is carried out through energy band diagrams and transfer characteristics. Simulated result shows point subthreshold slope (SS) of 19.14 mV/decade and ON to OFF current ratio (I_ON / I_OFF) of 2.66 × 10¹⁴ (I_ON at V_GS=1.5V, V_DS=1V and I_OFF at V_GS=0V, V_DS=1V) for gate length of 20nm and HfO₂ as gate oxide at room temperature. Which indicate that the DGPNTFET is a promising candidate for nano-scale, ambipolar free switch.

Keywords: Ambipolar effect, double gate PN diode based tunnel field effect transistor, high-κ dielectric material, subthreshold slope, tunnel field effect transistor.

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Authors: Nisha Harry

Abstract:

The study discussed in this article sought to assess whether a sense of professional efficacy mediates the relationship between personal factors and career adaptability. A quantitative cross-sectional survey approach was followed. A non–probability sample of (N = 409) of which predominantly early career and permanently employed black females in call centres in Africa participated in this study. In order to assess personal factors, the participants completed sense of meaningfulness and emotional intelligence measures. Measures of professional efficacy and career adaptability were also completed. The results of the mediational analysis revealed that professional efficacy significantly mediates the meaningfulness (sense of coherence) and career adaptability relationship, but not the emotional intelligence–career adaptability relationship. Call centre agents with professional efficacy are likely to be more work engaged as a result of their sense of meaningfulness and emotional intelligence.

Keywords: Call centre, professional efficacy, career adaptability, emotional intelligence.

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Authors: S. Zhuiykov, Zh. Hai, H. Xu, C. Xue

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Unique and distinctive properties could be obtained on such two-dimensional (2D) semiconductor as tungsten trioxide (WO₃) when the reduction from multi-layer to one fundamental layer thickness takes place. This transition without damaging single-layer on a large spatial resolution remained elusive until the atomic layer deposition (ALD) technique was utilized. Here we report the ALD-enabled atomic-layer-precision development of a single layer WO₃ with thickness of 0.77±0.07 nm on a large spatial resolution by using (^tBuN)₂W(NMe₂)₂ as tungsten precursor and H₂O as oxygen precursor, without affecting the underlying SiO₂/Si substrate. Versatility of ALD is in tuning recipe in order to achieve the complete WO₃ with desired number of WO₃ layers including monolayer. Governed by self-limiting surface reactions, the ALD-enabled approach is versatile, scalable and applicable for a broader range of 2D semiconductors and various device applications.

Keywords: Atomic layer deposition, tungsten oxide, WO3, two-dimensional semiconductors, single fundamental layer.

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Authors: Q. Zafar, R. Akram, Kh.S. Karimov, T.A. Khan, M. Farooq, M.M. Tahir

Abstract:

In this study we present the effect of elevated temperatures from 300K to 400K on the electrical properties of copper Phthalocyanine (CuPc) based organic field effect transistors (OFET). Thin films of organic semiconductor CuPc (40nm) and semitransparent Al (20nm) were deposited in sequence, by vacuum evaporation on a glass substrate with previously deposited Ag source and drain electrodes with a gap of 40 μm. Under resistive mode of operation, where gate was suspended it was observed that drain current of this organic field effect transistor (OFET) show an increase with temperature. While in grounded gate condition metal (aluminum) – semiconductor (Copper Phthalocyanine) Schottky junction dominated the output characteristics and device showed switching effect from low to high conduction states like Zener diode at higher bias voltages. This threshold voltage for switching effect has been found to be inversely proportional to temperature and shows an abrupt decrease after knee temperature of 360K. Change in dynamic resistance (Rd = dV/dI) with respect to temperature was observed to be -1%/K.

Keywords: Copper Phthalocyanine, Metal-Semiconductor Schottky Junction, Organic Field Effect Transistor, Switching effect, Temperature Sensor

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Authors: S. Mohd, Y. Mutoh, Y. Otsuka, Y. Miyashita, T. Koike, T. Suzuki

Abstract:

Scatter behavior of fatigue life in die-cast AM60B alloy was investigated. For comparison, those in rolled AM60B alloy and die-cast A365-T5 aluminum alloy were also studied. Scatter behavior of pore size was also investigated to discuss dominant factors for fatigue life scatter in die-cast materials. Three-parameter Weibull function was suitable to explain the scatter behavior of both fatigue life and pore size. The scatter of fatigue life in die-cast AM60B alloy was almost comparable to that in die-cast A365-T5 alloy, while it was significantly large compared to that in the rolled AM60B alloy. Scatter behavior of pore size observed at fracture nucleation site on the fracture surface was comparable to that observed on the specimen cross-section and also to that of fatigue life. Therefore, the dominant factor for large scatter of fatigue life in die-cast alloys would be the large scatter of pore size. This speculation was confirmed by the fracture mechanics fatigue life prediction, where the pore observed at fatigue crack nucleation site was assumed as the pre-existing crack.

Keywords: Fatigue life, Pore size, Scatter, Weibull distribution, Die-cast magnesium alloy

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Authors: Ria Millati, Fiametta A. Purwandari, Adhitya P. Sanjaya, Muhammad N. Cahyanto, I. Sarvari Horvath, Claes Niklasson, Mohammad J. Taherzadeh

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Pretreatment of oil palm empty fruit bunch (OPEFB) with N-Methylmorpholine-N-oxide (NMMO) to enhance biogas production was investigated. The pretreatments were performed at 90 and 120ºC for 1, 3, and 5 h using three different concentrations of NMMO of 73%, 79%, and 85%. The pretreated OPEFB was subsequently anaerobically digested to produce biogas. After pretreatment, there were no significant changes of the main composition of OPEFB and the maximum total solid recovery was 92%. The amorphous phase was increased up to 78% at pretreatment condition using 85% NMMO solution for 3 h at 120oC. In general, higher concentration of NMMO and higher temperature resulted in increased amorphous form and higher biogas production. The best results of biogas production reached enhancement of methane yield of 148% compared to the untreated OPEFB and increased in digestion of 94% compared to starch as reference.

Keywords: Oil palm empty fruit bunch, pretreatment, NMMO, biogas.

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Authors: R. Mahjoub, K. Maghsoudi Mehraban

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Since the heart of the hybrid system is the fuel cell and it has vital impact on efficiency and performance of cycle, in this study, the major modeling of electrochemical reaction within the fuel cell is analyzed. Also, solid oxide fuel cell is integrated with the gas turbine and thermodynamic analysis on different elements of hybrid system is applied. Next, in predefined operational points of hybrid cycle, the simulation results are obtained. Then, different source of irreversibility in fuel cell is modeled and influence of different major parameters on different irreversibility is computed and applied. Then, the effect of important parameters such as thickness and surface of electrolyte fuel cell are simulated in fuel cell and its dependency to these parameters is explained. At the end of the paper, different impact of parameters on fuel cell with a gas turbine and current density and voltage of fuel cell are simulated.

Keywords: Electrochemical analysis, Gas turbine, Hybrid system, Irreversibility analysis.

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Authors: J. R. Wang, W.Y. Li, H.T. Lin, J.H. Yang, C. Shih, S.W. Chen

Abstract:

Fuel rod analysis program transient (FRAPTRAN)  code was used to study the fuel rod performance during a postulated  large break loss of coolant accident (LBLOCA) in Maanshan nuclear  power plant (NPP). Previous transient results from thermal hydraulic  code, TRACE, with the same LBLOCA scenario, were used as input  boundary conditions for FRAPTRAN. The simulation results showed  that the peak cladding temperatures and the fuel centerline  temperatures were all below the 10CFR50.46 LOCA criteria. In  addition, the maximum hoop stress was 18 MPa and the oxide  thickness was 0.003mm for the present simulation cases, which are all  within the safety operation ranges. The present study confirms that this  analysis method, the FRAPTRAN code combined with TRACE, is an  appropriate approach to predict the fuel integrity under LBLOCA with  operational ECCS.

 

Keywords: —FRAPTRAN, TRACE, LOCA, PWR.

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Authors: K. E. Kaharudin, A. H. Hamidon, F. Salehuddin

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Vertical Double Gate (DG) Metal Oxide Semiconductor Field Effect Transistor (MOSFET) is believed to suppress various short channel effect problems. The gate to channel coupling in vertical DG-MOSFET are doubled, thus resulting in higher current density. By having two gates, both gates are able to control the channel from both sides and possess better electrostatic control over the channel. In order to ensure that the transistor possess a superb turn-off characteristic, the subs-threshold swing (SS) must be kept at minimum value (60-90mV/dec). By utilizing SILVACO TCAD software, an n-channel vertical DG-MOSFET was successfully designed while keeping the sub-threshold swing (SS) value as minimum as possible. From the observation made, the value of sub-threshold swing (SS) was able to be varied by adjusting the height of the silicon pillar. The minimum value of sub-threshold swing (SS) was found to be 64.7mV/dec with threshold voltage (V_TH) of 0.895V. The ideal height of the vertical DG-MOSFET pillar was found to be at 0.265 µm.

Keywords: DG-MOSFET, pillar, SCE, vertical

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Authors: Sher Muhammad, Mirza Muhammad Waqar

Abstract:

It is necessary to monitor and identify mangroves types and spatial extent near coastal areas because it plays an important role in coastal ecosystem and environmental protection. This research aims at identifying and mapping mangroves types along Karachi coast ranging from 24.79⁰ to 24.85⁰ in latitude and 66.91⁰ to 66.97⁰ in longitude using hyperspectral remote sensing data and techniques. Image acquired during February, 2012 through Hyperion sensor have been used for this research. Image pre processing includes geometric and radiometric correction followed by Minimum Noise Fraction (MNF) and Pixel Purity Index (PPI). The output of MNF and PPI has been analyzed by visualizing it in n-dimensions for end member extraction. Well distributed clusters on the n-dimensional scatter plot have been selected with the region of interest (ROI) tool as end members. These end members have been used as an input for classification techniques applied to identify and map mangroves species including Spectral Angle Mapper (SAM), Spectral Feature Fitting (SFF) and Spectral Information Diversion (SID). Only two types of mangroves namely Avicennia Marina (White Mangroves) and Avicennia germinans (Black Mangroves) have been observed throughout the study area.

Keywords: Mangrove, Hyperspectral, SAM, SFF, SID.

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Authors: K. Pipitthapan, S. Maksasithorn, P. Praserthdam, J. Panpranot, K. Suriye, S. Kunjara Na Ayudhya

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WO3/SiO2 catalysts were modified by an ion exchange method with sodium hydroxide or potassium hydroxide solution. The performance of the modified catalysts was tested in the metathesis of ethylene and trans-2-butene to propylene. During ion exchange, sodium and potassium ions played different roles. Sodium modified catalysts revealed constant trans-2-butene conversion and propylene selectivity when the concentrations of sodium in the solution were varied. In contrast, potassium modified catalysts showed reduction of the conversion and increase of the selectivity. From these results, potassium hydroxide may affect the transformation of tungsten oxide active species, resulting in the decrease in conversion whereas sodium hydroxide did not. Moreover, the modification of catalysts by this method improved the catalyst stability by lowering the amount of coke deposited on the catalyst surface.

Keywords: Acid sites, alkali metals, isomerization, metathesis.

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Authors: A. Bahar Ganiyeva, M. Sabuhi Tanriverdiyev

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The article analyzes state support and policy mechanisms aimed at driving tourism as one of the vibrant and rapidly developing economies. State programs and long-range strategic roadmaps and previous programs execution, results and their impact on the particular countries economy have been raised during the research. This theme provides a useful framework for discussions with a wider range of stakeholders as the implications arising are of importance both for academics and practitioners engaged in hospitality and tourism development and research. The impact that tourism has on sustainable regional development in emerging markets is highly substantial. For Azerbaijan, Turkey, Georgia, and Russia, with their rich natural resources and cultural heritage, tourism can be an important basis for economic expansion, and a way to form an acceptable image of the countries as safe, open, hospitable, and complex.

Keywords: Sustainable tourism, hospitality, destination, strategic roadmap, tourism, economy, growth, state support, mechanism, policy formation, state program.

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Authors: Martin Klaumünzer, Jakob Hübner, Denis Spitzer

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Within this paper, latest results on processing of energetic nanomaterials by means of the Spray Flash Evaporation technique are presented. This technology constitutes a highly effective and continuous way to prepare fascinating materials on the nano- and micro-scale. Within the process, a solution is set under high pressure and sprayed into an evacuated atomization chamber. Subsequent ultrafast evaporation of the solvent leads to an aerosol stream, which is separated by cyclones or filters. No drying gas is required, so the present technique should not be confused with spray dying. Resulting nanothermites, insensitive explosives or propellants and compositions are foreseen to replace toxic (according to REACH) and very sensitive matter in military and civil applications. Diverse examples are given in detail: nano-RDX (n-Cyclotrimethylentrinitramin) and nano-aluminum based systems, mixtures (n-RDX/n-TNT - trinitrotoluene) or even cocrystalline matter like n-CL-20/HMX (Hexanitrohexaazaisowurtzitane/ Cyclotetra-methylentetranitramin). These nanomaterials show reduced sensitivity by trend without losing effectiveness and performance. An analytical study for material characterization was performed by using Atomic Force Microscopy, X-Ray Diffraction, and combined techniques as well as spectroscopic methods. As a matter of course, sensitivity tests regarding electrostatic discharge, impact, and friction are provided.

Keywords: Continuous synthesis, energetic material, nanoscale, nanothermite, nanoexplosive.

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Authors: Nisa Rachmania Mubarik, Irni Mahagiani, Aris Tri Wahyudi

Abstract:

The objective of this research was to determine the potency of indigenous acid-aluminium tolerant Bradyrhizobium japonicum as producer of indole acetic acid (IAA) and applied it as nitrogen fixation on local soybeans viz Anjasmoro, Tanggamus (yellow soybean seeds), and Detam (black soybean seed). Three isolates of acid-aluminium tolerant Bradyrhizobium japonicum (BJ) were used in this research, i.e. BJ 11 (wt), BJ 11 (19) - BJ 11(wt) mutant, and USDA 110 as a reference isolate. All of isolates tested to produce the IAA by using Salkowsky method. Effect of IAA production by each of B. japonicum was tested on growth pouch and greenhouse using three varieties of soybean. All isolates could grow well and produce IAA on yeast mannitol broth (YMB) medium in the presence of 0.5 mM L-tryptophan. BJ 11 (19) produced the highest of IAA at 4 days incubation compared to BJ 11 (wt) and USDA 110. All tested isolates of Bradyrhizobium japonicum have showed effect on stimulating the formation of root nodules in soybean varieties grown on Leonard bottle. The concentration of IAA on root nodules of soybean symbiotic with B. japonicum was significantly different with control, except on the treatment using Tanggamus soybean.

Keywords: Acid-aluminium tolerant isolate, Bradyrhizobium japonicum, indole acetic acid, soybean.

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Authors: S. Chauhan, T. P. K. Grewal, S. K. Agrawal, V. K. Srivastava

Abstract:

Combustion of fuels in industrial and transport sector has lead to an alarming release of polluting gases to the atmosphere. Carbon monoxide is one such pollutant, which is formed as a result of incomplete oxidation of the fuel. In order to analyze the effect of catalyst on the reduction of CO emissions to the atmosphere, two catalysts Mn2O3 and Hopcalite are considered. A model was formed based on mass and energy balance equations. Results show that Hopcalite catalyst as compared to Mn2O3 catalyst helped in faster conversion of the polluting gas as the operating temperature of the hopcalite catalyst is much lower as compared to the operating temperature of Mn2O3 catalyst.

Keywords: Carbon monoxide, modeling, hopcalite, manganese oxide.

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Authors: Noor Ul Ain Bhatti, M. Junaid Khan, Javed Ahmad, Murtaza Saleem, Shahid M. Ramay, Saadat A. Siddiqi

Abstract:

Manganese oxide is being recently used as electrode material for rechargeable batteries. In this study, Al incorporated Mn₂O₃ compositions were synthesized to study the effect of Al doping on electrochemical performance of host material. Structural studies were carried out using X-ray diffraction analysis to confirm the phase stability and explore the lattice parameters, crystallite size, lattice strain, density and cell volume. Morphology and composition were analyzed using field emission scanning electron microscope and energy dispersive X-ray spectroscopy, respectively. Dynamic light scattering analysis was performed to observe the average particle size of the compositions. FTIR measurements exhibit the O-Al-O and O-Mn-O and Al-O bonding and with increasing the concentration of Al, the vibrational peaks of Mn-O become sharper. An enhanced electrochemical performance was observed in compositions with higher Al content.

Keywords: Mn2O3, electrode materials, energy storage and conversion, electrochemical performance.

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Authors: Devin Atkin, Orly Yadid-Pecht

Abstract:

The continual demands for increasing resolution and dynamic range in complimentary metal-oxide semiconductor (CMOS) image sensors have resulted in exponential increases in the amount of data that need to be read out of an image sensor, and existing readouts cannot keep up with this demand. Interesting approaches such as sparse and burst readouts have been proposed and show promise, but at considerable trade-offs in other specifications. To this end, we have begun designing and evaluating various readout topologies centered around an attempt to parallelize the sensor readout. In this paper, we have designed, simulated, and started testing a light-controlled oscillator topology with dual column and row readouts. We expect the parallel readout structure to offer greater speed and alleviate the trade-off typical in this topology, where slow pixels present a major framerate bottleneck.

Keywords: CMOS image sensors, high-speed capture, wide dynamic range, light controlled oscillator.

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Authors: Weixin Qian, Haitao Zhang, Hongfang Ma, Yongdi Liu, Weiyong Ying, Dingye Fang

Abstract:

The adsorption properties of CO and H2 on iron-based catalyst with addition of Zr and Ni were investigated using temperature programmed desorption process. It was found that on the carburized iron-based catalysts, molecular state and dissociative state CO existed together. The addition of Zr was preferential for the molecular state adsorption of CO on iron-based catalyst and the presence of Ni was beneficial to the dissociative adsorption of CO. On H2 reduced catalysts, hydrogen mainly adsorbs on the surface iron sites and surface oxide sites. On CO reduced catalysts, hydrogen probably existed as the most stable CH and OH species. The addition of Zr was not benefit to the dissociative adsorption of hydrogen on iron-based catalyst and the presence of Ni was preferential for the dissociative adsorption of hydrogen.

Keywords: adsorption, Fischer-Tropsch synthesis, iron-based catalysts

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