Search results for: interface pressure

Authors: Yanli Zhao, Jian Chen, Shouxiang Lu

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Flame spread over solid fuels in high pressure situations such as nuclear containment shells and hyperbaric oxygen chamber has potential to result in catastrophic disaster, thus requiring best knowledge. This paper reveals experimentally the flame spread behaviors over fuel cylinders in high pressures. The fuel used in this study is polyethylene and polymethyl methacrylate cylinders with 4mm diameter. Ambient gas is fixed as air and total pressures are varied from naturally normal pressure (100kPa) to elevated pressure (400kPa). Flame appearance, burning rate and flame spread were investigated experimentally and theoretically. Results show that high pressure significantly affects the flame appearance, which is as the pressure increases, flame color changes from luminous yellow to orange and the orange part extends down towards the base of flame. Besides, the average flame width and height, and the burning rate are proved to increase with increasing pressure. What is more, flame spread rates become higher as pressure increases due to the enhancement of heat transfer from flame to solid surface in elevated pressure by performing a simplified heat balance analysis.

Keywords: cylinder fuel, flame spread, heat transfer, high pressure

Procedia PDF Downloads 354

Authors: Fares Khalfallah, Zakaria Boumerzoug, Selvarajan Rajakumar, Elhadj Raouache

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The ceramic-aluminum bond is strongly present in industrial tools, due to the need to combine the properties of metals, such as ductility, thermal and electrical conductivity, with ceramic properties like high hardness, corrosion and wear resistance. In recent years, some joining techniques have been developed to achieve a good bonding between these materials such as brazing, diffusion bonding, ultrasonic joining and friction welding. In this work, AA1100 aluminum alloy rods were welded with Alumina 99.9 wt% ceramic rods, by friction welding. The effect of friction pressure on mechanical and structural properties of welded joints was studied. The welding was performed by direct friction welding machine. The welding samples were rotated at a constant rotational speed of 900 rpm, friction time of 4 sec, forging strength of 18 MPa, and forging time of 3 sec. Three different friction pressures were applied to 20, 34 and 45 MPa. The three-point bending test and Vickers microhardness measurements were used to evaluate the strength of the joints and investigate the mechanical properties of the welding area. The microstructure of joints was examined by optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that bending strength increased, and then decreased after reaching a maximum value, with increasing friction pressure. The SEM observation shows that the increase in friction pressure led to the appearance of cracks in the microstructure of the interface area, which is decreasing the bending strength of joints.

Keywords: welding of ceramic to aluminum, friction welding, alumina, AA1100 aluminum alloy

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Authors: P. Sawitri, S. Cdr. Sittha, T. Kritsana

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Flow forming is widely used in many industries, especially in defence technology industries. Pressure vessels requirements are high precision, light weight, seamless and optimum strength. For large pressure vessels, flow forming by 3 rollers machine were used. In case of long range rocket motor case flow forming and welding of pressure vessels have been used for manufacturing. Due to complication of welding process, researchers had developed 4 meters length pressure vessels without weldment by 4 rollers flow forming machine. Design and preparation of preform work pieces are performed. The optimization of flow forming parameter such as feed rate, spindle speed and depth of cut will be discussed. The experimental result shown relation of flow forming parameters to quality of flow formed tube and prototype pressure vessels have been made.

Keywords: flow forming, pressure vessel, four rollers, feed rate, spindle speed, cold work

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Authors: Sathish K. Gurupatham, Farhad Sayedzada, Naji Dauk, Valmiki Sooklal, Laura Ruhala

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It was shown recently that small particles and powders spontaneously disperse on liquid surfaces when they come into contact with the interface for the first time. This happens due to the combined effect of the capillary force, buoyant weight of the particle and the viscous drag that the particle experiences in the liquid. The particle undergoes oscillations normal to the interface before it comes to rest on the interface. These oscillations, in turn, induce a flow on the interface which disperses the particles radially outward. This phenomenon has a significant role in the pollination of sea plants such as Ruppia in which the formation of ‘pollen rafts’ is the first step. This paper investigates, experimentally, the influence of the temperature of the liquid on which this dispersion occurs. It was observed that the frequency of oscillations of the particles decreased with the increase in the temperature of the liquid. It is because the magnitude of capillary force also decreased when the temperature of the liquid increased.

Keywords: particle dispersion, capillary force, viscous drag, oscillations

Procedia PDF Downloads 341

Authors: Yuzman Yusoff, Siti Noor Harun, Noor Shelida Salleh, Tan Kong Yew

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This paper presents the design and characterization of analog readout interface circuits for ion sensitive field effect transistor (ISFET) and ion selective electrode (ISE) based sensor. These interface circuits are implemented using MIMOS’s 0.35um CMOS technology and experimentally characterized under 24-leads QFN package. The characterization evaluates the circuit’s functionality, output sensitivity and output linearity. Commercial sensors for both ISFET and ISE are employed together with glass reference electrode during testing. The test result shows that the designed interface circuits manage to readout signals produced by both sensors with measured sensitivity of ISFET and ISE sensor are 54mV/pH and 62mV/decade, respectively. The characterized output linearity for both circuits achieves above 0.999 rsquare. The readout also has demonstrated reliable operation by passing all qualifications in reliability test plan.

Keywords: readout interface circuit (ROIC), analog interface circuit, ion sensitive field effect transistor (ISFET), ion selective electrode (ISE), ion sensor electronics

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Authors: Pardeep Bishnoi, Mayank Srivastava, Mrityunjay Kumar Sinha

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This article represents the numerical investigation of the pressure and velocity field variation of the dynamics of pendant drop formation through a capillary tube. Numerical simulations are executed using volume of fluid (VOF) method in the computational fluid dynamics (CFD). In this problem, Non Newtonian fluid is considered as dispersed fluid whereas air is considered as a continuous fluid. Pressure contours at various time steps expose that pressure varies nearly hydrostatically at each step of the dynamics of drop formation. A result also shows the pressure variation of the liquid droplet during free fall in the computational domain. The evacuation of the fluid from the necking region is also shown by the contour of the velocity field. The role of surface tension in the Pressure contour of the dynamics of drop formation is also studied.

Keywords: pressure contour, surface tension, volume of fluid, velocity field

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Authors: Antanas Žiliukas, Mindaugas Kukis

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The work deals with cellular pressure vessels subjected to internal pressure. Their cellular insert can be used for placing liquids or gases, which is necessary to carry out technological processes, and the vessel itself has a good bearing capacity. Numerical calculations of the three core structures, which measure the influence of the inner cylinder thickness on maximum bearing capacity are presented. The calculations are compared using strength criteria and they show the different strength safety level.

Keywords: pressure, strength criterion, sandwich plate, cellular vessel

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Authors: Baofeng Pan, Heng Liu

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Because of the high strength and large carrying capacity, the semi-rigid base is widely used in modern road engineering. However, hydrodynamic pressure, which is one of the main factors to cause early damage of semi-rigid base, cannot be avoided in the nature environment when pavement is subjected to some loadings such as the passing vehicles. In order to investigating how moisture-induced-damage of semi-rigid base influenced by hydrodynamic pressure, a new and effective experimental research method is provided in this paper. The results show that: (a) The washing action of high hydrodynamic pressure is the direct cause of strength reducing of road semi-rigid base. (b) The damage of high hydrodynamic pressure mainly occurs at the beginning of the scoring test and with the increasing of testing time the influence reduces. (c) Under the same hydrodynamic pressure, the longer the specimen health age, the stronger ability to resist moisture induced damage.

Keywords: semi-rigid base, hydrodynamic pressure, moisture-induced-damage, experimental research

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Authors: Esmaeil Abbaszadeh Molaei, Zongyan Zhou, Aibing Yu

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The applications of liquid fluidizations have been increased in many parts of industries such as particle classification, backwashing of granular filters, crystal growth, leaching and washing, and bioreactors due to high-efficient liquid–solid contact, favorable mass and heat transfer, high operation flexibilities, and reduced back mixing of phases. In most of these multiphase operations the particles properties, i.e. size, density, and shape, may change during the process because of attrition, coalescence or chemical reactions. Previous studies, either experimentally or numerically, mainly have focused on studies of liquid-solid fluidized beds containing spherical particles; however, the role of particle shape on the hydrodynamics of liquid fluidized beds is still not well-known. A three-dimensional Discrete Element Model (DEM) and Computational Fluid Dynamics (CFD) are coupled to study the influence of particles shape on particles and liquid flow patterns in liquid-solid fluidized beds. In the simulations, ellipsoid particles are used to study the shape factor since they can represent a wide range of particles shape from oblate and sphere to prolate shape particles. Different particle shapes from oblate (disk shape) to elongated particles (rod shape) are selected to investigate the effect of aspect ratio on different flow characteristics such as general particles and liquid flow pattern, pressure drop, and particles orientation. First, the model is verified based on experimental observations, then further detail analyses are made. It was found that spherical particles showed a uniform particle distribution in the bed, which resulted in uniform pressure drop along the bed height. However for particles with aspect ratios less than one (disk-shape), some particles were carried into the freeboard region, and the interface between the bed and freeboard was not easy to be determined. A few particle also intended to leave the bed. On the other hand, prolate particles showed different behaviour in the bed. They caused unstable interface and some flow channeling was observed for low liquid velocities. Because of the non-uniform particles flow pattern for particles with aspect ratios lower (oblate) and more (prolate) than one, the pressure drop distribution in the bed was not observed as uniform as what was found for spherical particles.

Keywords: CFD, DEM, ellipsoid, fluidization, multiphase flow, non-spherical, simulation

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Authors: Ellisha Iling, Dayang Siti Hazimmah Ali

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Experimental composite boards were fabricated using oil palm (Elaeis guineensis Jacq) fronds particles by applying hot press pressure of 5MPa, 6MPa and 7MPa respectively. Modulus of rupture (MOR) and internal bond strength (IB) of the composite boards made with target density of 0.80 g/cm³ were evaluated. Composite board fabricated under hot press pressure of 5MPa had MOR and IB values of 16.27 and 4.34 N/mm² respectively. Corresponding values for composite board fabricated under hot press pressure of 6MPa were 16.76 and 5.41 N/mm² respectively. Whereas, the MOR and IB values of composite board fabricated under hot press pressure of 7MPa were 17.24 and 6.19 N/mm² respectively. All composite boards met the MOR and IB requirement stated in Japanese Industrial Standard (JIS). Based on results of this work, the strength of mechanical properties of composite board increased with increase of hot press pressure. This study revealed that the selection of applied pressure during fabrication of composite board is important to improve mechanical properties of composite boards.

Keywords: composite board, Elaeis guineensis Jacq. Fronds, hot press pressure, mechanical properties

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Authors: Syed Qasim Gilani, Muhammad Umair, Muhammad Noman, Syed Bilawal Shah, Aqib Abbasi, Muhammad Waheed

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Cardiovascular Diseases(CVD's) are the major cause of death in the world. The main reason for these deaths is the unavailability of first aid for heart failure. In many cases, patients die before reaching the hospital. We in this paper are presenting innovative online health service for Cardiac Patients. The proposed online health system has two ends. Users through device developed by us can communicate with their doctor through a mobile application. This interface provides them with first aid.Also by using this service, they have an easy interface with their doctors for attaining medical advice. According to the proposed system, we developed a device called Cardiac Care. Cardiac Care is a portable device which a patient can use at their home for monitoring heart condition. When a patient checks his/her heart condition, Electrocardiogram (ECG), Blood Pressure(BP), Temperature are sent to the central database. The severity of patients condition is checked using Artificial Intelligence Algorithm at the database. If the patient is suffering from the minor problem, our algorithm will suggest a prescription for patients. But if patient's condition is severe, patients record is sent to doctor through the mobile Android application. Doctor after reviewing patients condition suggests next step. If a doctor identifies the patient condition as critical, then the message is sent to the central database for sending an ambulance for the patient. Ambulance starts moving towards patient for bringing him/her to hospital. We have implemented this model at prototype level. This model will be life-saving for millions of people around the globe. According to this proposed model patients will be in contact with their doctors all the time.

Keywords: cardiovascular disease, classification, electrocardiogram, blood pressure

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Authors: Geuna Kim, Sanghyun Kim

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This study investigates various factors that may influence the ISM process, including the organization’s internal needs and external pressure, and examines the role of regulatory pressure in ISM development and performance. The 105 sets of data collected in a survey were tested against the research model using SEM. The results indicate that NP and TP had positive effects on the ISM process, except for perceived benefits. Regulatory pressure had a positive effect on the relationship between ISM awareness and ISM development and performance.

Keywords: information security management, need pull, technology push, regulatory pressure

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Authors: Abrar Al-Mutairi, Talal Al-Bazali

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In this study, changes in capillary entry pressure of shale, as it interacts with CO₂, under different temperatures (25 °C to 250 °C) have been investigated. The combined impact of temperature and petrophysical properties (water content, water activity, permeability and porosity) of shale was also addressed. Results showed that the capillary entry pressure of shale when it interacted with CO₂ was highly affected by temperature. In general, increasing the temperature decreased capillary entry pressure of shale. We believe that pore dilation, where pore throat size expands due to the application of heat, may have caused this decrease in capillary entry pressure of shale. However, in some cases we found that at higher temperature some shale samples showed that the temperature activated clay swelling may have caused an apparent decrease in pore throat radii of shale which translates into higher capillary entry pressure of shale. Also, our results showed that there is no distinct relationship between shale’s water content, water activity, permeability, and porosity on the capillary entry pressure of shale samples as it interacted with CO₂ at different temperatures.

Keywords: heat, threshold pressure, CO₂ sequestration, shale

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Authors: Nur H. Ahmad, Silvia S. Inge, Vanessa A. Julliete, A. Veraditias, Laila F. Febinda

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Abdominal obesity is a risk factor for metabolic syndrome and mostly found in adolescents. Waist circumference is related to abdominal obesity which has a significant effect on the increase of blood pressure. Inulin is one of prebiotic, that has health benefits by offering the potential for lipid management, that can be useful to decrease the risk factor of metabolic syndrome. The aim of the research is to evaluate the effect of 10 gram inulin-substituted ice cream in waist circumference and blood pressure of abdominal obesity adolescents. Inulin had the ability to produce Short Chain Fatty Acid which can improve blood pressure and waist circumference. Systolic blood pressure was significantly decreased in the treatment group (p=0.028) with the mean of reduction 7.35 ± 11.59 mmHg. However, diastolic blood pressure and waist circumference showed no significant effect. Waist circumference, systolic blood pressure and diastolic blood pressure was decreased in control group. These results suggest that inulin-substituted ice cream used as therapeutics and prevention for the early onset of metabolic syndrome.

Keywords: blood pressure, inulin, metabolic syndrome, waist circumference

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Authors: Qasem Qananwah, Ahmad Dagamseh, Hiam AlQuran, Khalid Shaker Ibrahim

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Blood pressure helps the physicians greatly to have a deep insight into the cardiovascular system. The determination of individual blood pressure is a standard clinical procedure considered for cardiovascular system problems. The conventional techniques to measure blood pressure (e.g. cuff method) allows a limited number of readings for a certain period (e.g. every 5-10 minutes). Additionally, these systems cause turbulence to blood flow; impeding continuous blood pressure monitoring, especially in emergency cases or critically ill persons. In this paper, the most important statistical features in the photoplethysmogram (PPG) signals were extracted to estimate the blood pressure noninvasively. PPG signals from more than 40 subjects were measured and analyzed and 12 features were extracted. The features were fed to principal component analysis (PCA) to find the most important independent features that have the highest correlation with blood pressure. The results show that the stiffness index means and standard deviation for the beat-to-beat heart rate were the most important features. A model representing both features for Systolic Blood Pressure (SBP) and Diastolic Blood Pressure (DBP) was obtained using a statistical regression technique. Surface fitting is used to best fit the series of data and the results show that the error value in estimating the SBP is 4.95% and in estimating the DBP is 3.99%.

Keywords: blood pressure, noninvasive optical system, principal component analysis, PCA, continuous monitoring

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Authors: Shahzad Yousaf, Imran Shafi

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This paper presents a new method for calculation of pressure loss coefficients by use of the artificial neural network (ANN) in tee junctions. Geometry and flow parameters are feed into ANN as the inputs for purpose of training the network. Efficacy of the network is demonstrated by comparison of the experimental and ANN based calculated data of pressure loss coefficients for combining flows in a tee junction. Reynolds numbers ranging from 200 to 14000 and discharge ratios varying from minimum to maximum flow for calculation of pressure loss coefficients have been used. Pressure loss coefficients calculated using ANN are compared to the models from literature used in junction flows. The results achieved after the application of ANN agrees reasonably to the experimental values.

Keywords: artificial neural networks, combining flow, pressure loss coefficients, solar collector tee junctions

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Authors: Manal Osman

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Sprinkler irrigation system became more popular to reduce water consumption and increase irrigation efficiency. The water distribution uniformity plays an important role in the performance of the sprinkler irrigation system. The use of low operating pressure instead of high operating pressure can be achieved many benefits including energy and water saving. An experimental study was performed to investigate the water distribution uniformity of the solid-set sprinkler irrigation system under low operating pressure. Different low operating pressures (62, 82, 102 and 122 kPa) were selected. The range of operating pressure was lower than the recommended in the previous studies to investigate the effect of low pressure on the water distribution uniformity. Different nozzle diameters (4, 5, 6 and 7 mm) were used. The outdoor single sprinkler test was performed. The water distribution of single sprinkler, the coefficients of uniformity such as coefficient of uniformity (CU), distribution uniformity of low quarter (DUlq), distribution uniformity of low half (DUlh), coefficient of variation (CV) and the distribution characteristics like rotation speed, throw radius and overlapping distance are presented in this paper.

Keywords: low operating pressure, sprinkler irrigation system, water distribution uniformity

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Authors: Lovro Štefan

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Background: The main purpose of the present study was to explore the correlations between physical activity and peak plantar pressure in dynamic mode. Methods: Participants were one hundred forty-six first-year university students (30.8% girls). Plantar pressure generated under each region of the foot (forefoot, midfoot, and heel) was measured by using Zebris dynamometric platform (Isny, Germany). The level of physical activity (PA) was calculated with the International Physical Activity questionnaire (IPAQ - short form). Results: In boys, forefoot peak plantar pressure was correlated with moderate PA (MPA; r=-0.21), vigorous PA (VPA; r=-0.18), and moderate-to-vigorous PA (MVPA; r=-0.28). No significant correlations with other foot regions (p>0.05) were observed. In girls, forefoot peak plantar pressure was correlated with MPA (r =-0.30), VPA (r=-0.39) and MVPA (r=-0.38). Also, heel peak pressure was significantly correlated with MPA (r=-0.33), while no significant correlations with VPA (r=0.05) and MVPA (r=-0.15) were observed. Conclusion: This study shows that different intensities of PA were mostly correlated with forefoot peak plantar pressure in both boys and girls. Therefore, strategies that reduce plantar pressure through a more active lifestyle should be implemented within the education system.

Keywords: pedobarography, youth, exercise, associations

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Authors: Asma Ashoul

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Nowadays, smartphones are playing a major role in our lives, by communicating with family, friends or using them to learn different things in life. Using smartphones to learn and teach today is something common to see in places like schools or colleges. Therefore, thinking about developing an app that teaches Arabic language may help some categories in society to learn a second language. For example, kids under the age of five or older would learn fast by using smartphones. The problem is based on the Arabic language, which is most like to be not used anymore. The developer assumed to develop an app that would help the younger generation on their learning the Arabic language. A research was completed about user interface design to help the developer choose appropriate layouts and designs. Developing the artefact contained different stages. First, analyzing the requirements with the client, which is needed to be developed. Secondly, designing the user interface design based on the literature review. Thirdly, developing and testing the application after it is completed contacting all the tools that have been used. Lastly, evaluation and future recommendation, which contained the overall view about the application followed by the client’s feedback. Gathering the requirements after having client meetings based on the interface design. The project was done following an agile development methodology. Therefore, this methodology helped the developer to manage to finish the work on time.

Keywords: developer, application, interface design, layout, Agile, client

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Authors: Talal Al-Bazali, S. Mohammad

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The threshold capillary pressure of shale caprocks is an important parameter in CO₂ storage modeling. A correct estimation of the threshold capillary pressure is not only essential for CO₂ storage modeling but also important to assess the overall economical and environmental impact of the design process. A standard step by step approach has to be used to measure the threshold capillary pressure of shale and non-wetting fluids at different temperatures. The objective of this work is to assess the impact of high temperature on the threshold capillary pressure of four different shales as they interacted with four different oil based muds, air, CO₂, N₂, and methane. This study shows that the threshold capillary pressure of shale and non-wetting fluid is highly impacted by temperature. An empirical correlation for the dependence of threshold capillary pressure on temperature when different shales interacted with oil based muds and gasses has been developed. This correlation shows that the threshold capillary pressure decreases exponentially as the temperature increases. In this correlation, an experimental constant (α) appears, and this constant may depend on the properties of shale and non-wetting fluid. The value for α factor was found to be higher for gasses than for oil based muds. This is consistent with our intuition since the interfacial tension for gasses is higher than those for oil based muds. The author believes that measured threshold capillary pressure at ambient temperature is misleading and could yield higher values than those encountered at in situ conditions. Therefore one must correct for the impact of temperature when measuring threshold capillary pressure of shale at ambient temperature.

Keywords: capillary pressure, shale, temperature, thresshold

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Authors: Stephanie Nihan, Jayson M. Fadrigalan, Pyay P. San, Steven M. Santos, Weihui Li

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People of all ages who use wheelchairs are left with the inconvenience of not having an easy way to take their vital signs. Typically, patients are required to visit the hospital in order to take the vital signs. VitalGO is a wheel chair system that equipped with medical devices to take vital signs and then transmit data to a mobile application for convenient, long term health monitoring. The vital signs include oxygen saturation, heart rate, and blood pressure, breathing rate and body temperature. Oxygen saturation and heart rate are monitored through pulse oximeter. Blood pressure is taken through a radar sensor. Breathing rate is derived through thoracic impedance while body temperature is measured through an infrared thermometer. The application receives data through bluetooth and stores in a database for review in a simple graphical interface. The application will have the ability to display this data over various time intervals such as a day, week, month, 3 months, 6 months and a year. The final system for the mobile app can also provide an interface for both the user and their physician(s) to record notes or keep record of daily symptoms that a patient might be having. The user’s doctor will be granted access by the user to view the patient information for assistance with a more accurate diagnosis. Also, this wheelchair accessory conveniently includes a foldable table/desk as somewhere to place an electronic device that may be used to access the app. The foldable table will overall contribute to the wheelchair user’s increased comfort and will give them somewhere to place food, a book, or any other form of entertainment that would normally be hard to juggle on their lap.

Keywords: wheel chair, vital sign, mobile application, telemedicine

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Authors: Dibyendu Das, Santanu Kumar Pal

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Milk protein lactoferrin (Lf) exhibits potent antibacterial activity due to its interaction with Gram-negative bacterial cell membrane component, lipopolysaccharide (LPS). This paper represents fabrication of new Liquid crystals (LCs) based biosensors to explore the interaction between Lf and LPS. LPS self-assembled at aqueous/LCs interface and orients interfacial nematic 4-cyano-4’- pentylbiphenyl (5CB) LCs in a homeotropic fashion (exhibiting dark optical image under polarized optical microscope). Interestingly, on the exposure of Lf on LPS decorated aqueous/LCs interface, an optical image of LCs changed from dark to bright indicating an ordering alteration of interfacial LCs from homeotropic to tilted/planar state. The ordering transition reflects strong binding between Lf and interfacial LPS that, in turn, perturbs the orientation of LCs. With the help of epifluorescence microscopy, we further affirmed the interfacial LPS-Lf binding event by imaging the presence of FITC tagged Lf at the LPS laden aqueous/LCs interface. Finally, we have investigated the conformational behavior of Lf in solution as well as in the presence of LPS using Circular Dichroism (CD) spectroscopy and further reconfirmed with Vibrational Circular Dichroism (VCD) spectroscopy where we found that Lf undergoes alpha-helix to random coil-like structure in the presence of LPS. As a whole the entire results described in this paper establish a robust approach to envisage the interaction between LPS and Lf through the ordering transitions of LCs at aqueous/LCs interface.

Keywords: endotoxin, interface, lactoferrin, lipopolysaccharide

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Authors: Meng-Yu Lin, Wan-Ju Lee

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Pore-water pressure, which mediates effective stress and shear strength at grain contacts, has a great influence on the motion of debris flow. The factors that control the diffusion of excess pore-water pressure play very important roles in the debris-flow motion. This research investigates these effects by solving the distribution of pore-water pressure numerically in an unsteady, surging motion of debris flow. The governing equations are the depth-averaged equations for the motion of debris-flow surges coupled with the one-dimensional diffusion equation for excess pore-water pressures. The pore-pressure diffusion equation is solved using a Fourier series, which may improve the accuracy of the solution. The motion of debris-flow surge is modelled using a Lagrangian particle method. From the computational results, the effects of pore-pressure diffusivities and the initial excess pore pressure on the formations of debris-flow surges are investigated. Computational results show that the presence of pore water can increase surge velocities and then changes the profiles of depth distribution. Due to the linear distribution of the vertical component of pore-water velocity, pore pressure dissipates rapidly near the bottom and forms a parabolic distribution in the vertical direction. Increases in the diffusivity of pore-water pressure cause the pore pressures decay more rapidly and then decrease the mobility of the surge.

Keywords: debris flow, diffusion, Lagrangian particle method, pore-pressure diffusivity, pore-water pressure

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Authors: Yuanhao Chang, Senbo Xiao, Zhiliang Zhang, Jianying He

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The role of nanoparticles (NPs) in enhanced oil recovery (EOR) is being increasingly emphasized. In this study, the motion of NPs and local stress distribution of tapped oil droplet/nanofluid in nanochannels are studied with coarse-grained modeling and molecular dynamic simulations. The results illustrate three motion patterns for NPs: hydrophilic NPs are more likely to adsorb on the channel and stay near the three-phase contact areas, hydrophobic NPs move inside the oil droplet as clusters and more mixed NPs are trapped at the oil-water interface. NPs in each pattern affect the flow of fluid and the interfacial thickness to various degrees. Based on the calculation of atomistic stress, the characteristic that the higher value of stress occurs at the place where NPs aggregate can be obtained. Different occurrence patterns correspond to specific local stress distribution. Significantly, in the three-phase contact area for hydrophilic NPs, the local stress distribution close to the pattern of structural disjoining pressure is observed, which proves the existence of structural disjoining pressure in molecular dynamics simulation for the first time. Our results guide the design and screen of NPs for EOR and provide a basic understanding of nanofluid applications.

Keywords: local stress distribution, nanoparticles, enhanced oil recovery, molecular dynamics simulation, trapped oil droplet, structural disjoining pressure

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Authors: Lila D. Sigdel, Chin J. Leo, Samanthika Liyanapathirana, Pan Hu, Minghao Lu

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Integral bridges are a class of bridges with integral or semi-integral abutments, designed without expansion joints in the bridge deck of the superstructure. Integral bridges are economical alternatives to conventional jointed bridges with lower maintenance costs and greater durability, thereby improving social and economic stability for the community. Integral bridges have also been proven to be effective in lowering the overall construction cost compared to the conventional type of bridges. However, there is significant uncertainty related to the design and analysis of integral bridges in response to cyclic thermal movements induced due to deck expansion and contraction. The cyclic thermal movements of the abutments increase the lateral earth pressures on the abutment and its foundation, leading to soil settlement and heaving of the backfill soil. Thus, the primary objective of this paper is to investigate the soil-abutment interaction under the cyclic translational movement of the abutment. Results from five experiments conducted to simulate different magnitudes of cyclic translational movements of abutments induced by thermal changes are presented, focusing on lateral earth pressure development at the abutment-soil interface. Test results show that the cycle number and magnitude of cyclic translational movements have significant effects on the escalation of lateral earth pressures. Experimentally observed earth pressure distributions behind the integral abutment were compared with the current design approaches, which shows that the most of the practices has under predicted the lateral earth pressure.

Keywords: integral bridge, cyclic thermal movement, lateral earth pressure, soil-structure interaction

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Authors: N. N. Joshi, G. K. Singh

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We present the stimuli implementation and verification of a Programmable Peripheral Interface (PPI) 8255. It involves a designing and verification of configurable intellectual property (IP) module of PPI protocol using Verilog HDL for implementation part and System Verilog for verification. The overview of the PPI-8255 presented then the design specification implemented for the work following the functional description and pin configuration of PPI-8255. The coverage report of design shows that our design and verification environment covered 100% functionality in accordance with the design specification generated by the Questa Sim 10.0b.

Keywords: Programmable Peripheral Interface (PPI), verilog HDL, system verilog, questa sim

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Authors: Nader Pourmahmoud, Amir Hassanzadeh

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This article investigates the effects of inlet pressure in a newly introduced vortex tube which has been equipped with an additional vortex chamber. A 3-D compressible turbulent flow computation has been carried out toward analysis of complex flow field in this apparatus. Numerical results of flows are derived by utilizing the standard k-ε turbulence model for analyzing high rotating complex flow field. The present research has focused on cooling effect and given a characteristics curve for minimum cool temperature. In addition, the effect of inlet pressure for both chambers has been studied in details. To be presented numerical results show that the effect of inlet pressure in second chamber has more important role in improving the performance of the vortex tube than first one. By increasing the pressure in the second chamber, cold outlet temperature reaches a higher decrease. When both chambers are fed with high pressure fluid, best operation condition of vortex tube occurs. However, it is not possible to feed both chambers with high pressure due to the conditions of working environment.

Keywords: energy separation, inlet pressure, numerical simulation, vortex chamber, vortex tube

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Authors: Shidvash Vakilipour, Mehdi Habibnia, Rouzbeh Riazi, Masoud Mohammadi, Mohammad H. Sabour

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The flow field passing through a highly loaded low pressure (LP) turbine cascade is numerically investigated at design and off-design conditions. The Field Operation And Manipulation (OpenFOAM) platform is used as the computational Fluid Dynamics (CFD) tool. Firstly, the influences of grid resolution on the results of k-ε, k-ω, and LES turbulence models are investigated and compared with those of experimental measurements. A numerical pressure under-shoot is appeared near the end of blade pressure surface which is sensitive to grid resolution and flow turbulence modeling. The LES model is able to resolve separation on a coarse and fine grid resolutions. Secondly, the off-design flow condition is modeled by negative and positive inflow incidence angles. The numerical experiments show that a separation bubble generated on blade pressure side is predicted by LES. The total pressure drop is also been calculated at incidence angle between -20◦ and +8◦. The minimum total pressure drop is obtained by k-ω and LES at the design point.

Keywords: low pressure turbine, off-design performance, openFOAM, turbulence modeling, flow separation

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Authors: S. S. Dol, M. S. Chan, S. F. Wong, J. S. Lim

Abstract:

Emulsion formation is unavoidable and can be detrimental to an oil field production. The presence of stable emulsions also reduces the quality of crude oil and causes more problems in the downstream refinery operations, such as corrosion and pipeline pressure drop. Hence, it is important to know the effects of emulsions in the pipeline. Light crude oil was used for the continuous phase in the W/O emulsions where the emulsions pass through a flow loop to test the pressure drop across the pipeline. The results obtained shows that pressure drop increases as water cut is increased until it peaks at the phase inversion of the W/O emulsion between 30% to 40% water cut. Emulsions produced by gradual constrictions show a lower stability as compared to sudden constrictions. Lower stability of emulsions in gradual constriction has the higher influence of pressure drop compared to a sudden sharp decrease in diameter in sudden constriction. Generally, sudden constriction experiences pressure drop of 0.013% to 0.067% higher than gradual constriction of the same ratio. Lower constriction ratio cases cause larger pressure drop ranging from 0.061% to 0.241%. Considering the higher profitability in lower emulsion stability and lower pressure drop at the developed flow region of different constrictions, an optimum design of constriction is found to be gradual constriction with a ratio of 0.5.

Keywords: constriction, pressure drop, turbulence, water-in-oil emulsions

Procedia PDF Downloads 306

Authors: Mina Boroujerdi, Javad Tavakoli

Abstract:

Hydrogels are extensively studied as matrices for the controlled release of drugs. To evaluate the mobility of embedded molecules, these drug delivery systems are usually characterized by release studies. In this contribution, an electronic device for swelling pressure measurement during drug release from hydrogel network was developed. Also, poly acrylic acid micro particles were prepared for prolonged and sustained controlled acetaminophen release. Effect of swelling pressure on drug release from micro particles studied under different environment pH in order to predict release profile in gastro-intestine medium. Swelling ratio and swelling pressure were measured in different pH.

Keywords: swelling pressure, drug delivery, hydrogel, polyelectrolyte

Procedia PDF Downloads 272