Search results for: surface pressure distribution

Authors: Justin Morton, Mohammad Khavari, Abhinav Priyadarshi, Nicole Grobert, Dmitry G. Eskin, Jiawei Mi, Kriakos Porfyrakis, Paul Prentice

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Ultrasonic cavitation is used for various processes and applications. Recently, ultrasonic assisted liquid phase exfoliation has been implemented to produce two dimensional nanomaterials. Depending on parameters such as input transducer power and the operational frequency used to induce the cavitation, bubble dynamics can be controlled and optimised. Using ultra-high-speed imagining and acoustic pressure measurements, a dual-frequency systemand its effect on bubble dynamics was investigated. A high frequency transducer (1.174 MHz) showed that bubble fragments and satellite bubbles induced from a low frequency transducer (24 kHz) were able to extend their lifecycle. In addition, this combination of ultrasonic frequencies generated higher acoustic emissions (∼24%) than the sum of the individual transducers. The dual-frequency system also produced an increase in cavitation zone size of∼3 times compared to the low frequency sonotrode. Furthermore, the high frequency induced cavitation bubbleswere shown to rapidly oscillate, although remained stable and did not transiently collapse, even in the presence of a low pressure field. Finally, the spatial distribution of satellite and fragment bubbles from the sonotrode were shown to increase, extending the active cavitation zone. These observations elucidated the benefits of using a dual-frequency system for generating nanomaterials with the aid of ultrasound, in deionised water.

Keywords: dual-frequency, cavitation, bubble dynamics, graphene

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Authors: Seung-Min Yang, Seong-Han Park, Sang-Hoon Lee, Seung-Wan Yoo, Chan-Soo Kim, Nong-Moon Hwang

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The theory of charged nanoparticles suggested that in many Chemical Vapour Depositions (CVD) processes, Charged Nanoparticles (CNPs) are generated in the gas-phase and become a building block of thin films and nanowires. Recently, the nanoparticle-based crystallization has become a big issue since the growth of nanorods or crystals by the building block of nanoparticles was directly observed by transmission electron microscopy observations in the liquid cell. In an effort to confirm charged gas-phase nuclei, that might be generated under conventional processing conditions of thin films and nanowires during CVD, we performed an in-situ measurement using differential mobility analyser and particle beam mass spectrometer. The size distribution and number density of CNPs were affected by process parameters such as precursor flow rate and working temperature. It was shown that many films and nanostructures, which have been believed to grow by individual atoms or molecules, actually grow by the building blocks of such charged nuclei. The electrostatic interaction between CNPs and the growing surface induces the self-assembly into films and nanowires. In addition, the charge-enhanced atomic diffusion makes CNPs liquid-like quasi solid. As a result, CNPs tend to land epitaxial on the growing surface, which results in the growth of single crystalline nanowires with a smooth surface.

Keywords: chemical vapour deposition, charged nanoparticle, electrostatic force, nanostructure evolution, differential mobility analyser, particle beam mass spectrometer

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Authors: Rekha M. Y., Punith Kumar, Anshul Kamboj, Chandan Srivastava

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Coatings plays an important role in providing protection for a substrate and in improving the surface quality. Graphene/graphene oxide (GO) using in coating systems provides an environmental friendly solution towards protection against corrosion. Issues such as, lack of scale, high cost, low quality limits the practical application of graphene/GO as corrosion resistant coating material. One other way to employ these materials for corrosion protection is to incorporate them into coatings that are conventionally used for corrosion protection. Due to the extraordinary properties of graphene/GO, it has been demonstrated that the coatings containing graphene/GO are more corrosion resistant than pure metal/alloy coatings. In the present work, Cr-graphene and SnZn-GO composite coatings were investigated in enhancing the corrosion resistant property when compared to pure Cr coating and pure SnZn coating respectively. All the coatings were electrodeposited over mild-steel substrate. Graphene and GO were synthesized by electrochemical exfoliation method and modified Hummers’ method respectively. In Cr coatings, the microstructural study revealed that the addition of formic acid in the coatings reduced the number of cracks in the coatings. Further addition of graphene in Cr coating enhanced the Cr coating’s morphology. Chemically synthesized ZnO nanoparticles were also embedded in the as-deposited Cr and Cr-graphene coatings to enhance the adhesion of the coating, to improve the surface finish and to increase the corrosion resistant property of the coatings. Diffraction analysis revealed that the addition of graphene also altered the texture of the Cr coatings. In SnZn alloy coatings, the morphological and topographical characterization revealed that the relative smoothness and compactness of the coatings increased with increase in the addition of GO in the coatings. The microstructural investigation revealed large-scale segregation of Zn-rich and Sn-rich phases in the pure SnZn coating. However, in SnZn-GO composite coating the uniform distribution of Zn phase in the Sn-rich matrix was observed. This distribution caused the early and uniform formation of ZnO, which is the corrosion product, yielding better corrosion resistance for the SnZn-GO composite coatings as compared to pure SnZn coating. A significant improvement in corrosion resistance in terms of reduction in corrosion current and corrosion rate and increase in the polarization resistance was observed in Cr coating containing graphene and in SnZn coatings containing GO.

Keywords: coatings, corrosion, electrodeposition, graphene, graphene-oxide

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Authors: A. Kumar, D. Himanshu, Ak Vaish, K. Usman , A. Singh, R. Misra, V. Atam, S. P. Verma, S. Singhal

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Introduction: Resistant and uncontrolled hypertension offer great challenge, in terms of higher risk of morbidity, mortality and not the least, difficulty in diagnosis and management. Our study tries to identify the importance of two crucial aspects of hypertension management, i.e. drug compliance and optimum dosing and also the effect of spironolactone on blood pressure in cases of resistant hypertension. Methodology: A prospective study was carried out among patients, who were referred as case of resistant hypertension to Hypertension Clinic at Gandhi memorial and associated hospital, Lucknow, India from August, 2013 to July 2014. A total of 122 Subjects having uncontrolled BP with ≥3 antihypertensives were selected. After ruling out secondary resistance and with appropriate lifestyle modifications, effect of adherence and optimum doses was seen with monitoring of BP. Only those having blood pressure still uncontrolled were true resistant. These patients were given spironolactone to see its effect on BP over next 12 weeks. Results: Mean baseline BP of all (n=122) patients was 150.4±7.2 mmHg systolic and 92.1±5.7 mmHg diastolic. After promoting adherence to the regimen, there was reduction of 4.20±3.65 mmHg systolic and 2.08±4.74 mmHg Diastolic blood pressure, with 26 patients achieving target blood pressure goal. Further reduction of 6.66±5.99 mmHg in systolic and 2.59±3.67 mmHg in diastolic BP was observed after optimizing the drug doses with another 66 patients achieving target blood pressure goal. Only 30 patients were true resistant hypertensive and prescribed spironolactone. Over 12 weeks, mean reduction of 20.62±3.65 mmHg in systolic and 10.08 ± 6.46 mmHg in diastolic BP was observed. Out of these 30, BP was controlled in 24 patients. Side effects observed were hyperkalemia in 2 patients and breast tenderness in 2 patients. Conclusion: Improper adherence and suboptimal regimen appear to be the important reasons for uncontrolled hypertension. By virtue of maintaining proper adherence to an optimum regimen, target BP goal can be reached in many without adding much to the regimen. Spironolactone is effective in patients with resistant hypertension, in terms of blood pressure reduction with minimal side effects.

Keywords: resistant, hypertension, spironolactone, blood pressure

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Authors: Najmul Hasan, Shiping Li, Chunli Liu

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The synergy effect of surface modifications using the acid treatment and noble metal (Au) deposition on the efficiency of SnFe2O4 (SFO) nano-octahedron photocatalyst has been investigated. Inorganic acids (H2SO4 and HNO3) were employed to compare the effects of different acids. It has been found that after corrosion treatment using H2SO4 and deposition of Au nanoparticles, SnFe2O4 nano-octahedron (Au-S-SFO) showed significantly enhanced photocatalytic activity under simulated light irradiation. Au-S-SFO was characterized by XRD, XPS, EDS, FTIR, Uv-vis-DRS, SEM, PL, and EIS analysis. The mechanism for CO2 reduction was investigated by scavenger tests. The stability of Au-S-SFO was confirmed by continuously repeated tests followed by XRD analysis. The surface corrosion treatment of SFO octahedron with H2SO4 could produce hydroxyl group (-OH) and sulfonic acid group (-SO3H) as reaction sites. These active sites not only enhanced the Au nanoparticles deposition to the acid treated SFO surface but also acted as the Brønsted acid sites that enhance the water adsorption and provide protons for CTC degradation and CO2 reduction. These effects improved the carrier separation and transfer efficiency. In addition, the photocatalytic efficiency was further enhanced by the surface plasmon resonance (SPR) effect of Au nanoparticles deposited on the surface of acid-treated SFO. As a result of the synergy of both acid treatment and SPR effect from the Au NPs, Au-S-SFO exhibited the highest CO2 reduction activity with 2.81, 1.92, and 2.69 times higher evolution rates for CO, CH4, and H2, respectively than that of pure SFO.

Keywords: surface modification, CO2 reduction, Au deposition, Gas-liquid interfacial plasma

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Authors: Partha Sarathi Majee, S. Bhattacharyya

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Migration of a core-shell soft particle under the influence of an external electric field in an electrolyte solution is studied numerically. The soft particle is coated with a positively charged polyelectrolyte layer (PEL) and the rigid core is having a uniform surface charge density. The Darcy-Brinkman extended Navier-Stokes equations are solved for the motion of the ionized fluid, the non-linear Nernst-Planck equations for the ion transport and the Poisson equation for the electric potential. A pressure correction based iterative algorithm is adopted for numerical computations. The effects of convection on double layer polarization (DLP) and diffusion dominated counter ions penetration are investigated for a wide range of Debye layer thickness, PEL fixed surface charge density, and permeability of the PEL. Our results show that when the Debye layer is in order of the particle size, the DLP effect is significant and produces a reduction in electrophoretic mobility. However, the double layer polarization effect is negligible for a thin Debye layer or low permeable cases. The point of zero mobility and the existence of mobility reversal depending on the electrolyte concentration are also presented.

Keywords: debye length, double layer polarization, electrophoresis, mobility reversal, soft particle

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Authors: Shoubhik Mandal, Debarghya Mallick, Abhishek Banerjee, R. Ganesan, P. S. Anil Kumar

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We report magnetotransport measurements in Bi₁Sb₁Te₁.₅Se₁.₅/RuCl₃ heterostructure nanodevices. Bi₁Sb₁Te₁.₅Se₁.₅ (BSTS) is a strong three-dimensional topological insulator (3D-TI) that hosts conducting topological surface states (TSS) enclosing an insulating bulk. α-RuCl₃ (namely, RuCl₃) is an anti-ferromagnet that is predicted to behave as a Kitaev-like quantum spin liquid carrying Majorana excitations. Temperature (T)-dependent resistivity measurements show the interplay between parallel bulk and surface transport channels. At T < 150 K, surface state transport dominates over bulk transport. Multi-channel weak anti-localization (WAL) is observed, as a sharp cusp in the magnetoconductivity, indicating strong spin-orbit coupling. The presence of top and bottom topological surface states (TSS), including a pair of electrically coupled Rashba surface states (RSS), are indicated. Non-linear Hall effect, explained by a two-band model, further supports this interpretation. Finally, a low-T logarithmic resistance upturn is analyzed using the Lu-Shen model, supporting the presence of gapless surface states with a π Berry phase.

Keywords: topological materials, electrical transport, Lu-Shen model, quantum spin liquid

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Authors: Mohieddine Benghersallah, Mohamed Zakaria Zahaf, Ali Medjber, Idriss Tibakh

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The objective of this study is to analyse the effects of cutting parameters on surface roughness in dry face milling using statistical techniques. We studied the effect of the microstructure of AISI 52100 steel on machinability before and after hardening. The machining tests were carried out on a high rigidity vertical milling machine with a 25 mm diameter face milling cutter equipped with micro-grain bicarbide inserts with PVD (Ti, AlN) coating in GC1030 grade. A Taguchi L9 experiment plan is adopted. Analysis of variance (ANOVA) was used to determine the effects of cutting parameters (Vc, fz, ap) on the roughness (Ra) of the machined surface. Regression analysis to assess the machinability of steel presented mathematical models of roughness and the combination of parameters to minimize it. The recorded results show that feed per tooth has the most significant effect on the surface condition for both steel treatment conditions. The best roughnesses were obtained for the hardened AISI 52100 steel.

Keywords: machinability, heat treatment, microstructure, surface roughness, Taguchi method

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Authors: Farshid Hajati, Soheila Gheisari, Ali Cheraghian, Yongsheng Gao

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This paper presents a new Surface Geodesic Derivative Pattern (SGDP) for matching textured deformable 3D surfaces. SGDP encodes micro-pattern features based on local surface higher-order derivative variation. It extracts local information by encoding various distinctive textural relationships contained in a geodesic neighborhood, hence fusing texture and range information of a surface at the data level. Geodesic texture rings are encoded into local patterns for similarity measurement between non-rigid 3D surfaces. The performance of the proposed method is evaluated extensively on the Bosphorus and FRGC v2 face databases. Compared to existing benchmarks, experimental results show the effectiveness and superiority of combining the texture and 3D shape data at the earliest level in recognizing typical deformable faces under expression, illumination, and pose variations.

Keywords: 3D face recognition, pose, expression, surface matching, texture

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Authors: Abdul Hadi Bin Abdol Rahim, Alhassan Salami Tijani

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Hydrogen produced by means of polymer electrolyte membrane electrolyzer (PEME) is one of the most promising methods due to clean and renewable energy source. In the process, some energy loss due to mass transfer through a PEM is caused by diffusion, electro-osmotic drag, and the pressure difference between the cathode channel and anode channel. In PEME water molecules and ionic particles transferred between the electrodes from anode to cathode, Extensive mixing of the hydrogen and oxygen at anode channel due to gases cross-over must be avoided. In recent times the consciousness of safety issue in high pressure PEME where the oxygen mix with hydrogen at anode channel could create, explosive conditions have generated a lot of concern. In this paper, the steady state and simulation analysis of gases crossover in PEME on the temperature and pressure effect are presented. The simulations have been analysis in MATLAB based on the well-known Fick’s Law of molecular diffusion. The simulation results indicated that as temperature increases, there is a significant decrease in operating voltage.

Keywords: diffusion, gases crosover, steady state, Fick’s law

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Authors: Nader Zirak, Mohammadali Shirinbayan, Abbas Tcharkhtchi

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Additive manufacturing is referred to as a method for fabrication of parts with a mechanism of layer by layer. Suitable economic efficiency and the ability to fabrication complex parts have made this method the focus of studies and industry. In recent years many studies focused on the fabrication of impellers, which is referred to as a key component of turbomachinery, through this technique. This study considers the important effect of the final surface quality of the impeller on the performance of the system, investigates the fabricated printed rotors through the fused deposition modeling with different process parameters. In this regard, the surface of each impeller was analyzed through the 3D scanner. The results show the vital role of surface quality on the final performance of the centrifugal compressor.

Keywords: additive manufacturing, impeller, centrifugal compressor, performance

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Authors: M. G. Tadesse, J. Yu, Y. Chen, L. Wang, V. Nierstrasz, C. Loghin

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Viscosity and surface tension are the fundamental rheological property of an ink for inkjet printing. In this work, we optimized the viscosity and surface tension of inkjet inks by varying the concentration of glycerol with water, PEDOT:PSS with glycerol and water, finally by adding the surfactant. The surface resistance of the sample was characterized by four-probe measurement principle. The change in volume of PEDOT:PSS in water, as well as the change in weight of glycerol in water has got a great influence on the viscosity on both temperature dependence and shear dependence behavior of the ink solution. The surface tension of the solution changed from 37 to 28 mN/m due to the addition of Triton. Varying the volume of PEDOT:PSS and the volume of glycerol in water has a great influence on the viscosity of the ink solution for inkjet printing. Viscosity drops from 12.5 to 9.5 mPa s with the addition of Triton at 25 oC. The PEDOT:PSS solution was found to be temperature dependence but not shear dependence as it is a Newtonian fluid. The sample was used to connect the light emitting diode (LED), and hence the electrical conductivity, with a surface resistance of 0.158 KΩ/square, was sufficient enough to give transfer current for LED lamp. The rheology of the inkjet ink is very critical for the successful droplet formation of the inkjet printing.

Keywords: shear rate, surface tension, surfactant, viscosity

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Authors: Lakshminarayanan, Vijayaraghavan, Krishnamurthy

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The ever-increasing demand for high efficiency in automotive and aerospace applications requires new materials to suit to high temperature applications. The Ceramic Matrix Composites nowadays find its applications for high strength and high temperature environments. In this paper, Al2O3 and Sic ceramic materials are taken in particulate form as matrix and reinforcement respectively. They are blended together in Ball Milling and compacted in Cold Compaction Machine by powder metallurgy technique. Scanning Electron Microscope images are taken for the samples in order to find out proper blending of powders. Micro harness testing is also carried out for the samples in Vickers Micro Hardness Testing Equipment. Surface grinding of the samples is also carried out in Surface Grinding Machine in order to find out grinding force estimates. The surface roughness of the grounded samples is also taken in Surface Profilometer. These are yielding promising results.

Keywords: ceramic matrix composite, cold compaction, material characterization, particulate and surface grinding

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Authors: Behic Mert

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This study reports a facile approach to structure soft solids from microfluidizer lycopene-rich plant based structure and oil. First carotenoid-rich plant material (pumpkin was used in this study) processed with high-pressure microfluidizer to release lycopene molecules, then an emulsion was formed by mixing processed plant material and oil. While, in emulsion state lipid soluble carotenoid molecules were allowed to dissolve in the oil phase, the fiber material of plant material provided the network which was required for emulsion stabilization. Additional hydrocolloids (gelatin, xhantan, and pectin) up to 0.5% were also used to reinforce the emulsion stability and their impact on final product properties were evaluated via rheological, textural and oxidation studies. Finally, water was removed from emulsion phase by drying in a tray dryer at 40°C for 36 hours, and subsequent shearing resulted in soft solid (ole gel) structures. The microstructure of these systems was revealed by cryo-scanning electron microscopy. Effect of hydrocolloids on total lycopene and surface lycopene contents were also evaluated. The surface lycopene was lowest in gelatin containing oleo gels and highest in pectin-containing oleo gels. This study outlines the novel emulsion-based structuring method that can be used to encapsulate lycopene without the need of separate extraction of them.

Keywords: lycopene, encapsulation, fiber, oleo gel

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Authors: Serge Provost, Yishan Zang

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Following a review of various approaches that are utilized for classifying the tail behavior of a distribution, an easily implementable methodology that relies on an arctangent transformation is presented. The classification criterion is actually based on the difference between two specific quantiles of the transformed distribution. The resulting categories enable one to classify distributional tails as distinctly short, short, nearly medium, medium, extended medium and somewhat long, providing that at least two moments exist. Distributions possessing a single moment are said to be long tailed while those failing to have any finite moments are classified as having an extremely long tail. Several illustrative examples will be presented.

Keywords: arctangent transformation, tail classification, heavy-tailed distributions, distributional moments

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Authors: Wenqian Zhang, Xuelin Wang, Yujin Hu, Siyang Wang

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The subsurface layer of a component plays a significant role in its service performance. Any surface mechanical process during fabrication can introduce a deformed layer near the surface, which can be related to the microstructure alteration and strain hardening, and affects the mechanical properties and corrosion resistance of the material. However, there exists a great difficulty in determining the subsurface deformation induced by surface machining. In this study, electron backscatter diffraction (EBSD) was used to study the deformed layer of surface milled 316 stainless steel. The microstructure change was displayed by the EBSD maps and characterized by misorientation variation. The results revealed that the surface milling resulted in heavily nonuniform deformations in the subsurface layer and even in individual grains. The direction of the predominant grain deformation was about 30-60 deg to the machined surface. Moreover, a local deformation rate (LDR) was proposed to quantitatively evaluate the local deformation degree. Both of the average and maximum LDRs were utilized to characterize the deformation trend along the depth direction. It was revealed that the LDR had a strong correlation with the development of grain and sub-grain boundaries. In this work, a scan step size of 1.2 μm was chosen for the EBSD measurement. A LDR higher than 18 deg/μm indicated a newly developed grain boundary, while a LDR ranged from 2.4 to 18 deg/μm implied the generation of a sub-grain boundary. And a lower LDR than 2.4 deg/μm could only introduce a slighter deformation and no sub-grain boundary was produced. According to the LDR analysis with the evolution of grain or sub grain boundaries, the deformed layer could be classified into four zones: grain broken layer, seriously deformed layer, slightly deformed layer and non-deformed layer.

Keywords: surface machining, EBSD, subsurface layer, local deformation

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Authors: Huma Shareef, Ghazala H. Rizwani, Ahsana Dar

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In traditional medicine Cardiospermum halicacabum L. (Sapindeaceae) is used against various ailments. In current investigation searching a new remedy that will available easily, non expensive, able to lower hypertension and standardize blood pressure, made us to develop an herbal medicine. Crude ethanol extract of C. halicacabum and its various fractions ethyl acetate and butanol showed a dose-dependent hypotensive effect in anaesthetized rats. The trachea was exposed and freed from connective tissue and incubated by cannula to facilitate spontaneous respiration. The right carotid artery and left jugular vein were cannulated with polyethylene tubing PE-50 for monitoring blood pressure changes via pressure transducer (Gould P23 ID) connected to a Grass model 79D polygraph and for i.v. injection, respectively. Drugs or the plant extracts were administered at a constant volume of 0.5 ml/kg, followed by injection of 0.2 ml of saline that flushed the cannula. Systolic, diastolic and mean arterial blood pressure (MABP) was measured in mm Hg and heart rate in beats/min. Ethanol extract of C. halicacabum showed a significant activity at 50 mg/kg dose. Ethyl acetate fraction (10, 20, 30, 40, and 50 mg/kg) induced dose dependent fall in systolic and diastolic blood pressure, heart rate of rats. At 10-30 mg/kg the hypotensive effect was non significantly reduced by 10 -15%. However, the extract at 40 mg/kg induced significant hypotensive effect calculated as 30.95±3.2% MABP and this effect persists till 50 mg/kg. The higher polar fraction (butanol) of the whole plant failed to produce any significant response against MABP at all the tested doses (10-50 mg/kg). C. halicacabum lowers blood pressure, exerts a dose-dependent hypotensive effect, can be used as hypotensor.

Keywords: cardiospermum halicacabum, calcium channel blocker, hypotensive, various extracts

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Authors: Hamed Sarbazy, Zohre Gholipour Haftkhani, Ali Safari, Pejman Hosseiniun

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Scientific and industrial progress in the past two decades has resulted in energy distribution systems based on power electronics, as an enabling technology in various industries and building management systems can be considered. Grading and standardization module power electronics systems and its use in a distributed control system, a strategy for overcoming the limitations of using this system. The purpose of this paper is to investigate strategies for scheduling and control structure of standard modules is a power electronic systems. This paper introduces the classical control methods and disadvantages of these methods will be discussed, The hierarchical control as a mechanism for distributed control structure of the classification module explains. The different levels of control and communication between these levels are fully introduced. Also continue to standardize software distribution system control structure is discussed. Finally, as an example, the control structure will be presented in a DC distribution system.

Keywords: application management, hardware management, power electronics, building blocks

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Authors: N. R. Putra, A. H. Abdul Aziz, A. S. Zaini, Z. Idham, F. Idrus, M. Z. Bin Zullyadini, M. A. Che Yunus

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The content of omega-3 in soybean oil is important in the development of infants and is an alternative for the omega-3 in fish oils. The investigation of extraction of soybean oil is needed to obtain the bioactive compound in the extract. Supercritical carbon dioxide extraction is modern and green technology to extract herbs and plants to obtain high quality extract due to high diffusivity and solubility of the solvent. The aim of this study was to obtain the optimum condition of soybean oil extraction by modified supercritical carbon dioxide. The soybean oil was extracted by using modified supercritical carbon dioxide (SC-CO₂) under the temperatures of 40, 60, 80 °C, pressures of 150, 250, 350 Bar, and constant flow-rate of 10 g/min as the parameters of extraction processes. An experimental design was performed in order to optimize three important parameters of SC-CO₂ extraction which are pressure (X₁), temperature (X₂) to achieve optimum yields of soybean oil. Box Behnken Design was applied for experimental design. From the optimization process, the optimum condition of extraction of soybean oil was obtained at pressure 338 Bar and temperature 80 °C with oil yield of 2.713 g. Effect of pressure is significant on the extraction of soybean oil by modified supercritical carbon dioxide. Increasing of pressure will increase the oil yield of soybean oil.

Keywords: soybean oil, SC-CO₂ extraction, yield, optimization

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Authors: Ibrahim Tiryakioglu, Mehmet Ali Ugur, Caglar Ozkaymak

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The development of GNSS technology has led to increasingly widespread and successful applications of GNSS surveys for monitoring crustal movements. However, multi-period GPS survey solutions have not been applied in monitoring vertical surface deformation. This study uses long-term GNSS time series that are required to determine vertical deformations. In recent years, the surface deformations that are parallel and semi-parallel to Bolvadin fault have occurred in Western Anatolia. These surface deformations have continued to occur in Bolvadin settlement area that is located mostly on alluvium ground. Due to these surface deformations, a number of cracks in the buildings located in the residential areas and breaks in underground water and sewage systems have been observed. In order to determine the amount of vertical surface deformations, two continuous GNSS stations have been established in the region. The stations have been operating since 2015 and 2017, respectively. In this study, GNSS observations from the mentioned two GNSS stations were processed with GAMIT/GLOBK (GNSS Analysis Massachusetts Institute of Technology/GLOBal Kalman) program package to create a coordinate time series. With the time series analyses, the GNSS stations’ behavior models (linear, periodical, etc.), the causes of these behaviors, and mathematical models were determined. The study results from the time series analysis of these two 2 GNSS stations shows approximately 50-80 mm/yr vertical movement.

Keywords: Bolvadin fault, GAMIT, GNSS time series, surface deformations

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Authors: Solmaz Eskandarion, Haniyeh Eftekhar, Amin Fallahi

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Introduction: Nowadays cosmetic dentistry has gained greater attention because of the changing demands of dentistry patients. Composite resin restorations play an important role in the field of esthetic restorations. Due to the variation between the resin composites, it is important to be aware of their mechanical properties and surface roughness. So, the aim of this study was to compare the mechanical properties (surface hardness, compressive strength, diametral tensile strength) and surface roughness of four kinds of resin composites after thermal aging process. Materials and Method: 10 samples of each composite resins (Gradia-direct (GC), Filtek Z250 (3M), G-ænial (GC), Filtek Z350 (3M- filtek supreme) prepared for evaluation of each properties (totally 120 samples). Thermocycling (with temperature 5 and 55 degree of centigrade and 10000 cycles) were applied. Then, the samples were tested about their compressive strength and diametral tensile strength using UTM. And surface hardness was evaluated with Microhardness testing machine. Either surface roughness was evaluated with Scanning electron microscope after surface polishing. Result: About compressive strength (CS), Filtek Z250 showed the highest value. But there were not any significant differences between 4 groups about CS. Either Filtek Z250 detected as a composite with highest value of diametral tensile strength (DTS) and after that highest to lowest DTS was related to: Filtek Z350, G-ænial and Gradia-direct. And about DTS all of the groups showed significant differences (P<0.05). Vickers Hardness Number (VHN) of Filtek Z250 was the greatest. After that Filtek Z350, G-ænial and Gradia-direct followed it. The surface roughness of nano-filled composites was less than Microhybrid composites. Either the surface roughness of GC Ganial was a little greater than Filtek Z250. Conclusion: This study indicates that there is not any evident significant difference between the groups amoung their mechanical properties. But it seems that Filtek Z250 showed slightly better mechanical properties. About surface roughness, nanofilled composites were better that Microhybrid.

Keywords: mechanical properties, surface roughness, resin composite, compressive strength, thermal aging

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Authors: Wanru Huang, Fujun Wang, Chaoyue Wang, Yuan Tang, Zhifeng Yao, Ruofu Xiao, Xin Chen

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Rotating stall in centrifugal pump is an unsteady flow phenomenon that causes instabilities and high hydraulic losses. It typically occurs at low flow rates due to large flow separation in impeller blade passage. In order to reveal the influence of incoming flow conditions on rotating stall in centrifugal pump, a numerical method for investigating rotating stall was established. This method is based on a modified SST k-ω turbulence model and a fine mesh model was adopted. The calculated flow velocity in impeller by this method was in good agreement with PIV results. The effects of flow rate and sealing-ring leakage on stall characteristics of centrifugal pump were studied by using the proposed numerical approach. The flow structures in impeller under typical flow rates and typical sealing-ring leakages were analyzed. It is found that the stall vortex frequency and circumferential propagation velocity increase as flow rate decreases. With the flow rate decreases from 0.40Qd to 0.30Qd, the stall vortex frequency increases from 1.50Hz to 2.34Hz, the circumferential propagation velocity of the stall vortex increases from 3.14rad/s to 4.90rad/s. Under almost all flow rate conditions where rotating stall is present, there is low frequency of pressure pulsation between 0Hz-5Hz. The corresponding pressure pulsation amplitude increases with flow rate decreases. Taking the measuring point at the leading edge of the blade pressure surface as an example, the flow rate decreases from 0.40Qd to 0.30Qd, the pressure fluctuation amplitude increases by 86.9%. With the increase of leakage, the flow structure in the impeller becomes more complex, and the 8-shaped stall vortex is no longer stable. On the basis of the 8-shaped stall vortex, new vortex nuclei are constantly generated and fused with the original vortex nuclei under large leakage. The upstream and downstream vortex structures of the 8-shaped stall vortex have different degrees of swimming in the flow passage, and the downstream vortex swimming is more obvious. The results show that the proposed numerical approach could capture the detail vortex characteristics, and the incoming flow conditions have significant effects on the stall vortex in centrifugal pumps.

Keywords: centrifugal pump, rotating stall, numerical simulation, flow condition, vortex frequency

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Authors: Young-Hun Lee, Tae-Gwan Kim, Jong-Kyu Kim, Young-Chul Park

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In this study, Spring safety valve Heat - structure coupled analysis was carried out. Full analysis procedure and performing thermal analysis at a maximum temperature, them to the results obtained through to give an additional load and the pressure on the valve interior, and Disc holder Heat-Coupled structure Analysis was carried out. Modeled using a 3D design program Solidworks, For the modeling of the safety valve was used 3D finite element analysis program ANSYS. The final result to be obtained through the Analysis examined the stability of the maximum displacement and the maximum stress to the valve internal components occurring in the high-pressure conditions.

Keywords: finite element method, spring safety valve, gap, stress, strain, deformation

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Authors: Silvano Salvador, Maryam Zarrinderakht, Alan Martin

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Open pits, which are the result of mining, are filled by water over time until the water reaches the elevation of the local water table and generates mine pit lakes. There are several specific regulations about the water quality of pit lakes, and mining operations should keep the quality of groundwater above pre-defined standards. Therefore, an accurate, acceptable numerical model predicting pit lakes’ water balance and water quality is needed in advance of mine excavation. We carry on analyzing and developing the model introduced by Crusius, Dunbar, et al. (2002) for pit lakes. This model, called “PitMod”, simulates the physical and geochemical evolution of pit lakes over time scales ranging from a few months up to a century or more. Here, a lake is approximated as one-dimensional, horizontally averaged vertical layers. PitMod calculates the time-dependent vertical distribution of physical and geochemical pit lake properties, like temperature, salinity, conductivity, pH, trace metals, and dissolved oxygen, within each model layer. This model considers the effect of pit morphology, climate data, multiple surface and subsurface (groundwater) inflows/outflows, precipitation/evaporation, surface ice formation/melting, vertical mixing due to surface wind stress, convection, background turbulence and equilibrium geochemistry using PHREEQC and linking that to the geochemical reactions. PitMod, which is used and validated in over 50 mines projects since 2002, incorporates physical processes like those found in other lake models such as DYRESM (Imerito 2007). However, unlike DYRESM PitMod also includes geochemical processes, pit wall runoff, and other effects. In addition, PitMod is actively under development and can be customized as required for a particular site.

Keywords: pit lakes, mining, modeling, hydrology

Procedia PDF Downloads 158

Authors: Abu Afree Andalib, Rafiur Rahman, Md Mezbah Uddin

Abstract:

The main objective of this work is to anatomize on the various parameters of AGM 88 missile anatomized using FSI module in Ansys. Computational fluid dynamics is used for the study of fluid flow pattern and fluidic phenomenon such as drag, pressure force, energy dissipation and shockwave distribution in water. Using finite element analysis module of Ansys, structural parameters such as stress and stress density, localization point, deflection, force propagation is determined. Separate analysis on structural parameters is done on Abacus. State of the art coupling module is used for FSI analysis. Fine mesh is considered in every case for better result during simulation according to computational machine power. The result of the above-mentioned parameters is analyzed and compared for two phases using graphical representation. The result of Ansys and Abaqus are also showed. Computational Fluid Dynamics and Finite Element analyses and subsequently the Fluid-Structure Interaction (FSI) technique is being considered. Finite volume method and finite element method are being considered for modelling fluid flow and structural parameters analysis. Feasible boundary conditions are also utilized in the research. Significant change in the interaction and interference pattern while the impact was found. Theoretically as well as according to simulation angled condition was found with higher impact.

Keywords: FSI (Fluid Surface Interaction), impact, missile, high viscous fluid, CFD (Computational Fluid Dynamics), FEM (Finite Element Analysis), FVM (Finite Volume Method), fluid flow, fluid pattern, structural analysis, AGM-88, Ansys, Abaqus, meshing, k-omega, turbulence model

Procedia PDF Downloads 467

Authors: Yongyu Duo, Xiaogang Liu, Qingrui Yue

Abstract:

The anchor plays a critical role in the utilization of the tensile strength of carbon fiber-reinforced polymer (CFRP) plate when it is applied for the prestressed retrofitted and cable structures. In this paper, the anchor behavior of planar clamping anchor (PCA) under different interface treatment forms and normal pressures was investigated by the uniaxial static tensile test. Two interface treatment forms were adopted, including pure friction and the coupling action of friction and bonding. The results indicated that the load-bearing capacity of PCA could be obviously improved by the coupling action of friction and bonding compared with the action of pure friction. Under the normal pressure of 11 MPa, 22 MPa, and 33 MPa, the load-bearing capacity of PCA was enhanced by 164.61%, 68.40%, and 52.78%, respectively, and the tensile strength of the CFRP plate was fully exploited when the normal pressure reached 44 MPa. In addition, the experimental coefficient of static friction between the galling CFRP plate and a sandblasted steel plate was in the range of 0.28-0.30, corresponding to various normal pressure. Moreover, the failure mode was determined by the interface treatment form and normal pressure. The research in this paper has important guiding significance to optimize the design of the mechanical clamping anchor, contributing to promoting the application of CFRP plate in reinforcement and cable structure.

Keywords: PCA, CFRP plate, interface treatment form, normal pressure, friction, coupling action

Procedia PDF Downloads 81

Authors: Amir Peyman Soleymani, Jasna Jankovic

Abstract:

The augmented demand of the clean and renewable energy has necessitated the fuel cell and battery industries to produce more efficient devices at the lower prices, which can be achieved through the improvement of the electrode. Microstructural characterization, as one of the main materials development tools, plays a pivotal role in the production of better clean energy devices. In this study, methods for characterization and studying of the defects and components distribution were performed on the polymer electrolyte membrane fuel cell (PEMFC) and Li-ion battery (LIB) electrodes in 2D and 3D. The particles distribution, porosity, mechanical defects, and component distribution were studied by Scanning Electron Microscope (SEM), SEM-Focused Ion Beam (SEM-FIB), and Scanning Transmission Electron Microscope equipped with Energy Dispersive Spectroscopy (STEM-EDS). The 3D results obtained from X-ray Computed Tomography (XCT) revealed the pathways for electron and ion conductivity and defects progression maps. Computer-aided methods (Avizo) were employed to simulate the properties and performance of the microstructure in the electrodes. The suggestions were provided to improve the performance of PEMFCs and LIBs by adjusting the microstructure and the distribution of the components in the electrodes.

Keywords: PEM fuel cells, Li-ion batteries, 2D and 3D imaging, materials characterizations

Procedia PDF Downloads 154

Authors: Sanjeev Kumar, Vikas Kumar

Abstract:

Inconel 718 (IN718) is a high strength nickel-based superalloy designed for high-temperature applications up to 650 °C. It is widely used in gas turbines of jet engines and related aerospace applications because of its good mechanical properties and structural stability at elevated temperatures. Because of good performance ratio and excellent process capability, this alloy has been used predominantly for aeronautic engine components like compressor disc and compressor blade. The main precipitates that contribute to high-temperature strength of IN718 are γʹ Ni₃(Al, Ti) and mainly γʹʹ (Ni₃ Nb). Various processes have been used for modification of the surface of components, such as Laser Shock Peening (LSP), Conventional Shot Peening (SP) and Ultrasonic Shot Peening (USP) to induce compressive residual stress (CRS) and development of fine-grained structure in the surface region. Surface nanostructure by ultrasonic shot peening is a novel methodology of surface modification to improve the overall performance of structural components. Surface nanostructure was developed on the peak aged IN718 superalloy using USP and its effect was studied on low cycle fatigue (LCF) life. Nanostructure of ~ 49 to 73 nm was developed in the surface region of the alloy by USP. The gage section of LCF samples was USPed for 5 minutes at a constant frequency of 20 kHz using StressVoyager to modify the surface. Strain controlled cyclic tests were performed for non-USPed and USPed samples at ±Δεt/2 from ±0.50% to ±1.0% at strain rate (ė) 1×10⁻³ s⁻¹ under reversal loading (R=‒1) at room temperature. The fatigue life of the USPed specimens was found to be more than that of the non-USPed ones. LCF life of the USPed specimen at Δεt/2=±0.50% was enhanced by more than twice of the non-USPed specimen.

Keywords: IN718 superalloy, nanostructure, USP, LCF life

Procedia PDF Downloads 112

Authors: Perla Elizabeth Jimarez Rocha, Carolina Daniela Tejeda Franco, Arturo Minor Martínez, Annel Gomez Coello

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One of the biggest problems in developing new therapies for the management and treatment of voice disorders is the difficulty of objectively evaluating the results of each treatment. A system was proposed that captures and records voice signals, in addition to analyzing the vocal quality (fundamental frequency, zero crossings, energy, and amplitude spectrum), as well as the subglottic pressure (cm H2O) during the sustained phonation of the vowel / a /; a recording system is implemented, as well as an interactive system that records information on subglottic pressure. In Mexico City, a control group of 31 patients with phoniatric pathology is proposed; non-invasive tests were performed for these most common vocal pathologies (Nodules, Polyps, Irritative Laryngitis, Ventricular Dysphonia, Laryngeal Cancer, Dysphonia, and Dysphagia). The most common pathology was irritative laryngitis (32%), followed by vocal fold paralysis (unilateral and bilateral,19.4 %). We take into consideration men and women in the pathological groups due to the physiological difference. They were separated in gender by the difference in the morphology of the respiratory tract.

Keywords: amplitude spectrum, energy, fundamental frequency, subglottic pressure, zero crossings

Procedia PDF Downloads 120

Authors: P. Makendran, M. Pragadeesh, N. Narash, N. Manikandan, A. Rajasri, V. Sanal Kumar

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The growing severity of government-obligatory emissions legislation has required continuous improvement in catalysts performance and the associated reactor systems. IC engines emit a lot of harmful gases into the atmosphere. These gases are toxic in nature and a catalytic converter is used to convert these toxic gases into less harmful gases. The catalytic converter converts these gases by Oxidation and reduction reaction. Stoichiometric engines usually use the three-way catalyst (TWC) for simultaneously destroying all of the emissions. CO and NO react to form CO2 and N2 over one catalyst, and the remaining CO and HC are oxidized in a subsequent one. Literature review reveals that typically precious metals are used as a catalyst. The actual reactor is composed of a washcoated honeycomb-style substrate, with the catalyst being contained in the washcoat. The main disadvantage of a catalytic converter is that it exerts a back pressure to the exhaust gases while entering into them. The objective of this paper is to optimize the back pressure developed by the catalytic converter through geometric optimization of catalystic converter. This can be achieved by designing a catalyst with a optimum cone angle and a more surface area of the catalyst substrate. Additionally, the arrangement of the pores in the catalyst substrate can be changed. The numerical studies have been carried out using k-omega turbulence model with varying inlet angle of the catalytic converter and the length of the catalyst substrate. We observed that the geometry optimization is a meaningful objective for the lucrative design optimization of a catalytic converter for industrial applications.

Keywords: catalytic converter, emission control, reactor systems, substrate for emission control

Procedia PDF Downloads 906