Search results for: high speed milling

Authors: Liliia N. Butymova, Vladimir Ya Modorskii

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To ensure the gas transmittal GCU's efficient operation, leakages through the labyrinth packings (LP) should be minimized. Leakages can be minimized by decreasing the LP gap, which in turn depends on thermal processes and possible rotor vibrations and is designed to ensure absence of mechanical contact. Vibration mitigation allows to minimize the LP gap. It is advantageous to research influence of processes in the dynamic gas-structure system on LP vibrations. This paper considers influence of rotor vibrations on LP gas dynamics and influence of the latter on the rotor structure within the FSI unidirectional dynamical coupled problem. Dependences of nonstationary parameters of gas-dynamic process in LP on rotor vibrations under various gas speeds and pressures, shaft rotation speeds and vibration amplitudes, and working medium features were studied. The programmed multi-processor ANSYS CFX was chosen as a numerical computation tool. The problem was solved using PNRPU high-capacity computer complex. Deformed shaft vibrations are replaced with an unyielding profile that moves in the fixed annulus "up-and-down" according to set harmonic rule. This solves a nonstationary gas-dynamic problem and determines time dependence of total gas-dynamic force value influencing the shaft. Pressure increase from 0.1 to 10 MPa causes growth of gas-dynamic force oscillation amplitude and frequency. The phase shift angle between gas-dynamic force oscillations and those of shaft displacement decreases from 3π/4 to π/2. Damping constant has maximum value under 1 MPa pressure in the gap. Increase of shaft oscillation frequency from 50 to 150 Hz under P=10 MPa causes growth of gas-dynamic force oscillation amplitude. Damping constant has maximum value at 50 Hz equaling 1.012. Increase of shaft vibration amplitude from 20 to 80 µm under P=10 MPa causes the rise of gas-dynamic force amplitude up to 20 times. Damping constant increases from 0.092 to 0.251. Calculations for various working substances (methane, perfect gas, air at 25 ˚С) prove the minimum gas-dynamic force persistent oscillating amplitude under P=0.1 MPa being observed in methane, and maximum in the air. Frequency remains almost unchanged and the phase shift in the air changes from 3π/4 to π/2. Calculations for various working substances (methane, perfect gas, air at 25 ˚С) prove the maximum gas-dynamic force oscillating amplitude under P=10 MPa being observed in methane, and minimum in the air. Air demonstrates surging. Increase of leakage speed from 0 to 20 m/s through LP under P=0.1 MPa causes the gas-dynamic force oscillating amplitude to decrease by 3 orders and oscillation frequency and the phase shift to increase 2 times and stabilize. Increase of leakage speed from 0 to 20 m/s in LP under P=1 MPa causes gas-dynamic force oscillating amplitude to decrease by almost 4 orders. The phase shift angle increases from π/72 to π/2. Oscillations become persistent. Flow rate proved to influence greatly on pressure oscillations amplitude and a phase shift angle. Work medium influence depends on operation conditions. At pressure growth, vibrations are mostly affected in methane (of working substances list considered), and at pressure decrease, in the air at 25 ˚С.

Keywords: aeroelasticity, labyrinth packings, oscillation phase shift, vibration

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Authors: Karel Šebesta, Jiří Žáček, Matuš Salva, Mohammad Housam

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Drivers of agricultural vehicles are exposed to continuous vibration caused by driving over rough terrain. The long-term effects of these vibrations could start with a decreased level of vigilance at work and could reach the level of several health problems. Therefore, eliminating the vibration to maximize the comfort of the driver is essential for better/longer performance. One of the modern damping systems, which can deal with this problem is the Semi-active (S/A) suspension system featuring a Magnetorheological (MR) damper. With this damper, the damping level can be adjusted using varying currents through the coil. Adjustments of the damping force can be carried out continuously based on the evaluated data (position and acceleration of seat) by the control algorithm. The advantage of this system is the wide dynamic range and the high speed of force response time. Compared to other S/A or active systems, the MR damper does not need as much electrical power, and the system is much simpler. This paper aims to prove the effectiveness of this damping system used in the tractor seat. The vibration testing stand was designed and manufactured specifically for this type of research, which is used to simulate vibrations with constant amplitude at variable frequency.

Keywords: magnetorheological damper, semi-active suspension, seat scissor mechanism, sky-hook

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Authors: Dinko Vuleta, Dejan Madić, Goran Sporiš, Nebojša Trajković

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The aim of this study was to determine the effects of gymnastics program in school on skill-related fitness in early adolescent students. The study involved 58 adolescent students (12.82±0.54 years; Height 156.81±8.16 cm; 53.46±12.31 kg) from primary school divided into two groups, following the randomization. The gymnastic group was involved in a 12 week of gymnastics classes, while the control group only participated in usual PE classes which consisted of multi-sport activities. The variables were selected within the several fitness batteries, measuring coordination (polygon backwards), upper and lower body strength standing long jump and medicine ball throw), speed (20 m sprint) and agility (4x10 test). Pre-test to post-test values showed significant improvements in all tested variables (p<0.05), except for the 4x10m test, where there were no significant improvements in neither of the groups (p>0.05). Significant interactions of time by group were observed for coordination, sprint speed, standing long jump and medicine ball throw (p<0.05). The results showed significant increase in skill-related fitness of the participants in the gymnastic group compared to the control group. Therefore, participation in gymnastics must be recommended as a positive foundational activity for school-aged children, from early childhood to adulthood. Additionally, the results can provide useful information in optimizing the training loads of pupils involved in gymnastic training throughout PE classes.

Keywords: effects, PE classes, physical fitness, training

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Authors: Charalambos C. Cleanthous, Ryan Sain, Tabitha Black, Stephen Vera, Suzanne Milton

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A concern when administering questionnaires is whether the participant is providing information that is accurate. The results may be invalid because the person is trying to present oneself in an unrealistic positive manner referred to as ‘faking good’, or in an unrealistic negative manner known as ‘faking bad’. The Balanced Inventory of Desirable Responding (BIDR) was used to assess commercial pilots’ responses on the two subscales of the BIDR: impression management (IM) and self-deceptive enhancement (SDE) that result in high or low scores. Thus, the BIDR produces four valid profiles: IM low and SDE low, IM high and SDE low, IM low and SDE high, and IM high and SDE high. The various profiles were used to compare the respondents’ answers to crew resource management (CRM) items developed from the USA Federal Aviation Administration’s (FAA) guidelines for CRM composition and training. Of particular interest were the results on the IM subscale. The comparisons between those scoring high (lying or faking) versus those low on the IM suggest that there were significant differences regarding their views of the various dimensions of CRM. One of the more disconcerting conclusions is that the high IM scores suggest that the pilots were trying to impress rather than honestly answer the questions regarding their CRM training and practice.

Keywords: USA commercial pilots, crew resource management, faking, social desirability

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Authors: Bjornar Kjellstadli, Shaher A. I. Shalfawi

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The aim of this study was to investigate the effect of strength training Cluster set-method compared to traditional set-method 30 m sprinting time and maximum strength in squats and bench-press. Thirteen Physical Education students, 7 males and 6 females between the age of 19-28 years old were recruited. The students were random divided in three groups. Traditional set group (TSG) consist of 2 males and 2 females aged (±SD) (22.3 ± 1.5 years), body mass (79.2 ± 15.4 kg) and height (177.5 ± 11.3 cm). Cluster set group (CSG) consist of 3 males and 2 females aged (22.4 ± 3.29 years), body mass (81.0 ± 24.0 kg) and height (179.2 ± 11.8 cm) and a control group (CG) consist of 2 males and 2 females aged (21.5 ± 2.4 years), body mass (82.1 ± 17.4 kg) and height (175.5 ± 6.7 cm). The intervention consisted of performing squat and bench press at 70% of 1RM (twice a week) for 8 weeks using 10 repetition and 4 sets. Two types of strength-training methods were used , cluster set (CS) where the participants (CSG) performed 2 reps 5 times with a 10 s recovery in between reps and 50 s recovery between sets, and traditional set (TS) where the participants (TSG) performed 10 reps each set with 90 s recovery in between sets. The pre-tests and post-tests conducted were 1 RM in both squats and bench press, and 10 and 30 m sprint time. The 1RM test were performed with Eleiko XF barbell (20 kg), Eleiko weight plates, rack and bench from Hammerstrength. The speed test was measured with the Brower speed trap II testing system (Brower Timing Systems, Utah, USA). The participants received an individualized training program based on the pre-test of the 1RM. In addition, a mid-term test of 1RM was carried out to adjust training intensity. Each training session were supervised by the researchers. Beast sensors (Milano, Italy) were also used to monitor and quantify the training load for the participants. All groups had a statistical significant improvement in bench press 1RM (TSG 1RM from 56.3 ± 28.9 to 66 ± 28.5 kg; CSG 1RM from 69.8 ± 33.5 to 77.2 ± 34.1 kg and CG 1RM from 67.8 ± 26.6 to 72.2 ± 29.1 kg), whereas only the TSG (1RM from 84.3 ± 26.8 to 114.3 ± 26.5 kg) and CSG (1RM from 100.4 ± 33.9 to 129 ± 35.1 kg) had a statistical significant improvement in Squats 1RM (P < 0.05). However, a between groups examination reveals that there were no marked differences in 1RM squat performance between TSG and CSG (P > 0.05) and both groups had a marked improvements compared to the CG (P < 0.05). On the other hand, no differences between groups were observed in Bench press 1RM. The within groups results indicate that none of the groups had any marked improvement in the distances from 0-10 m and 10-30 m except the CSG which had a notable improvement in the distance from 10-30 m (-0.07 s; P < 0.05). Furthermore, no differences in sprinting abilities were observed between groups. The results from this investigation indicate that traditional set strength training at 70% of 1RM gave close results compared to Cluster set strength training at the same intensity. However, the results indicate that the cluster set had an effect on flying time (10-30 m) indicating that the velocity at which those repetitions were performed could be the explanation factor of this this improvement.

Keywords: physical performance, 1RM, pushing velocity, velocity based training

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Authors: Daohong Yang, Xiang Zhang, Lei Li, Wanting Zhou

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Visual Simultaneous Localization and Mapping (VSLAM) is a technology that obtains information in the environment for self-positioning and mapping. It is widely used in computer vision, robotics and other fields. Many visual SLAM systems, such as OBSLAM3, employ a constant-speed motion model that provides the initial pose of the current frame to improve the speed and accuracy of feature matching. However, in actual situations, the constant velocity motion model is often difficult to be satisfied, which may lead to a large deviation between the obtained initial pose and the real value, and may lead to errors in nonlinear optimization results. Therefore, this paper proposed a motion model based on acceleration, which can be applied on most SLAM systems. In order to better describe the acceleration of the camera pose, we decoupled the pose transformation matrix, and calculated the rotation matrix and the translation vector respectively, where the rotation matrix is represented by rotation vector. We assume that, in a short period of time, the changes of rotating angular velocity and translation vector remain the same. Based on this assumption, the initial pose of the current frame is estimated. In addition, the error of constant velocity model was analyzed theoretically. Finally, we applied our proposed approach to the ORBSLAM3 system and evaluated two sets of sequences on the TUM dataset. The results showed that our proposed method had a more accurate initial pose estimation and the accuracy of ORBSLAM3 system is improved by 6.61% and 6.46% respectively on the two test sequences.

Keywords: error estimation, constant acceleration motion model, pose estimation, visual SLAM

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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: Kevin Wongleedee

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The purposes of this research were to study the image of a flight attendant career from the perspective of high school students in Bangkok and to study the level of interest to pursue a flight attendant career. A probability random sampling of 400 students was utilized. Half the sample group came from private high schools and the other half came from public high schools. A questionnaire was used to collect the data and small in-depth interviews were also used to get their opinions about the image and their level of interest in the flight attendant career. The findings revealed that the majority of respondents had a medium level of interest in the flight attendant career. High school students who majored in Math-English were more interested in a flight attendant career than high school students who majored in Science-Math with a 0.05 level of significance. The image of flight attendant career was rated as a good career with a chance to travel to many countries. The image of flight attendance career can be ranked as follows: a career with a chance to travel, a career with ability to speak English, a career that requires punctuality, a career with a good service mind, and a career with an understanding of details. The findings from the in-depth interviews revealed that the major obstacles that prevented high school students from choosing a flight attendant as a career were their ability to speak English, their body proportions, and lack of information.

Keywords: flight attendant, high school students, image, media engineering

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Authors: Noemia Gomes de Mattos de Mesquita, José Eduardo Ferreira de Oliveira, Arimatea Quaresma Ferraz

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Stops to exchange cutting tool, to set up again the tool in a turning operation with CNC or to measure the workpiece dimensions have a direct influence on production. The premature removal of the cutting tool results in high cost of machining since the parcel relating to the cost of the cutting tool increases. On the other hand, the late exchange of cutting tool also increases the cost of production because getting parts out of the preset tolerances may require rework for its use when it does not cause bigger problems such as breaking of cutting tools or the loss of the part. Therefore, the right time to exchange the tool should be well defined when wanted to minimize production costs. When the flank wear is the limiting tool life, the time predetermination that a cutting tool must be used for the machining occurs within the limits of tolerance can be done without difficulty. This paper aims to show how the life of the cutting tool can be calculated taking into account the cutting parameters (cutting speed, feed and depth of cut), workpiece material, power of the machine, the dimensional tolerance of the part, the finishing surface, the geometry of the cutting tool and operating conditions of the machine tool, once known the parameters of Taylor algebraic structure. These parameters were raised for the ABNT 1038 steel machined with cutting tools of hard metal.

Keywords: machining, productions, cutting condition, design, manufacturing, measurement

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Authors: Tarik Ouslimane, Abdenour Lami, Salaheddine Aoudj, Mouna Hecini, Ouahiba Bouchelaghem, Nadjib Drouiche

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Slurry waste is a byproduct generated from the slicing process of multi-crystalline silicon ingots. This waste can be used as a secondary resource to recover high purity silicon which has a great economic value. From the management perspective, the ever increasing generation of kerf slurry waste loss leads to significant challenges for the photovoltaic industry due to the current low use of slurry waste for silicon recovery. Slurry waste, in most cases, contains silicon, silicon carbide, metal fragments and mineral-oil-based or glycol-based slurry vehicle. As a result, of the global scarcity of high purity silicon supply, the high purity silicon content in slurry has increasingly attracted interest for research. This paper presents a critical overview of the current techniques employed for high purity silicon recovery from kerf slurry waste. Hydrometallurgy is continuously a matter of study and research. However, in this review paper, several new techniques about the process of high purity silicon recovery from slurry waste are introduced. The purpose of the information presented is to improve the development of a clean and effective recovery process of high purity silicon from slurry waste.

Keywords: Kerf-loss, slurry waste, silicon carbide, silicon recovery, photovoltaic, high purity silicon, polyethylen glycol

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Authors: Hajer Najjar, Riad Bourguiba, Jaouhar Mouine

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Reduced instruction set computer (RISC) processors are widely used because of their multiple advantages. In fact, they are based on a simple instruction set so that they increase the speed of the processor and reduce its energy consumption. In this paper, we will present a basic RISC architecture processor that will be developed later to converge to a new architecture with runtime reconfiguration.

Keywords: processor, RISC, DLX, pipeline, runtime reconfiguration

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Authors: Pallavi Gajjar, Vinayak Malhotra

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Rockets have been known to have played a predominant role in spacecraft propulsion. The quintessential aspect of combustion-related requirements of a rocket engine is the minimization of the surrounding risks/hazards. Over time, it has become imperative to understand the combustion rate variation in presence of external energy source(s). Rocket propulsion represents a special domain of chemical propulsion assisted by high speed flows in presence of acoustics and thermal source(s). Jet noise leads to a significant loss of resources and every year a huge amount of financial aid is spent to prevent it. External heat source(s) induce high possibility of fire risk/hazards which can sufficiently endanger the operation of a space vehicle. Appreciable work had been done with justifiable simplification and emphasis on the linear variation of external energy source(s), which yields good physical insight but does not cater to accurate predictions. Present work experimentally attempts to understand the correlation between inter-energy conversions with the non-linear placement of external energy source(s). The work is motivated by the need to have better fire safety and enhanced combustion. The specific objectives of the work are a) To interpret the related energy transfer for combustion in presence of alternate external energy source(s) viz., thermal and acoustic, b) To fundamentally understand the role of key controlling parameters viz., separation distance, the number of the source(s), selected configurations and their non-linear variation to resemble real-life cases. An experimental setup was prepared using incense sticks as potential fuel and paraffin wax candles as the external energy source(s). The acoustics was generated using frequency generator, and source(s) were placed at selected locations. Non-equidistant parametric experimentation was carried out, and the effects were noted on regression rate changes. The results are expected to be very helpful in offering a new perspective into futuristic rocket designs and safety.

Keywords: combustion, acoustic energy, external energy sources, regression rate

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Authors: Abdolrasoul Daneshjoo, Fatemeh Akbari Ghara

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Background and Purpose: Obesity is an increasing factor in cardiovascular disease and serum levels of cellular adhesion molecule. It plays an important role in predicting risk for coronary artery disease. The purpose of this research was to study the effect of eight weeks moderate intensity interval training and curcumin intake on ICAM-1 & VCAM-1 levels of menopausal fat rats. Materials and methods: in this study, 28 Wistar Menopausal fat rats aged 6-8 weeks with an average weight of 250-300 (gr) were randomly divided into four groups: control, curcumin supplement, moderate intensity interval training and moderate intensity interval training + curcumin supplement. (7 rats each group). The training program was planned as 8 weeks and 3 sessions per week. Each session consisted of 10 one-min sets with 50 percent intensity and the 2-minutes interval between sets in the first week. Subjects started with 14 meters per minute, and 2 (m/min) was added to increase their speed weekly until the speed of 28 (m/min) in the 8th week. Blood samples were taken 48 hours after the last training session, and ICAM-1 A and VCAM-1 levels were measured. SPSS software, one-way analysis of variance (ANOVA) and Pearson correlation coefficient were used to assess the results. Results: The results showed that eight weeks of training and taking curcumin had significant effects on ICAM-1 levels of the rats (p ≤ 0.05). However, it had no significant effect on VCAM-1 levels in menopausal obese rates (p ≥ 0.05). There was no significant correlation between the levels of ICAM-1 and VCAM-1 in eight weeks training and taking curcumin. Conclusion: Implementation of moderate intensity interval training and the use of curcumin decreased ICAM-1 significantly.

Keywords: curcumin, interval training , ICMA, VCAM

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Authors: N. Hernández Huertas, F. Rojas Mora

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Sounding rockets are aerospace vehicles that were developed in the mid-20th century, and since then numerous investigations have been executed with the aim of innovate in this type of technology. However, the costs associated to the production of this type of technology are usually quite high, and therefore the challenge that exists today is to be able to reduce them. In this way, the main objective of this document is to present the design process of a Colombian aerospace mission capable to reach the thermosphere using low-cost “Candy” type solid fuel engines. This mission is the latest development of the Uniandes Aerospace Project (PUA for its Spanish acronym), which is an undergraduate and postgraduate research group at Universidad de los Andes (Bogotá, Colombia), dedicated to incurring in this type of technology. In this way, the investigations that have been carried out on Candy-type solid fuel, which is a compound of potassium nitrate and sorbitol, have allowed the production of engines powerful enough to reach space, and which represents a unique technological advance in Latin America and an important development in experimental rocketry. In this way, following the engineering iterative design methodology was possible to design a 2-stage sounding rocket with 1 solid fuel engine in each one, which was then simulated in RockSim V9.0 software and reached an apogee of approximately 150 km above sea level. Similarly, a speed equal to 5 Mach was obtained, which after performing a finite element analysis, it was shown that the rocket is strong enough to be able to withstand such speeds. Under these premises, it was demonstrated that it is possible to build a high-power aerospace mission at low cost, using Candy-type solid fuel engines. For this reason, the feasibility of carrying out similar missions clearly depends on the ability to replicate the engines in the best way, since as mentioned above, the design of the rocket is adequate to reach supersonic speeds and reach space. Consequently, with a team of at least 3 members, the mission can be obtained in less than 3 months. Therefore, when publishing this project, it is intended to be a reference for future research in this field and benefit the industry.

Keywords: aerospace missions, Candy type solid propellant engines, design of solid rockets, experimental rocketry, low costs missions

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Authors: Gautam Kumar Saharia, Sagardeep Talukdar, Riki Dutta, Sudipta Nandy

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The physics informed neural network (PINN) method opens up an approach for numerically solving nonlinear partial differential equations leveraging fast calculating speed and high precession of modern computing systems. We construct the PINN based on strong universal approximation theorem and apply the initial-boundary value data and residual collocation points to weekly impose initial and boundary condition to the neural network and choose the optimization algorithms adaptive moment estimation (ADAM) and Limited-memory Broyden-Fletcher-Golfard-Shanno (L-BFGS) algorithm to optimize learnable parameter of the neural network. Next, we improve the PINN with a weighted loss function to obtain both the bright and dark soliton solutions of Fokas-Lenells equation (FLE). We find the proposed scheme of adjustable weight coefficients into PINN has a better convergence rate and generalizability than the basic PINN algorithm. We believe that the PINN approach to solve the partial differential equation appearing in nonlinear optics would be useful to study various optical phenomena.

Keywords: deep learning, optical Soliton, neural network, partial differential equation

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Authors: Abdelmalek Ouannou, Adil Brouri, Laila Kadi, Tarik

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Switched reluctance motor (SRM) has a major interest in a large domain as in electric vehicle driving because of its wide range of speed operation, high performances, low cost, and robustness to run under degraded conditions. The purpose of the paper is to develop a new analytical approach for modeling SRM parameters. Then, an identification scheme is proposed to obtain the SRM parameters. Since the SRM is featured by a highly nonlinear behavior, modeling these devices is difficult. Then, it is convenient to develop an accurate model describing the SRM. Furthermore, it is always operated in the magnetically saturated mode to maximize the energy transfer. Accordingly, it is shown that the SRM can be accurately described by a generalized polynomial Hammerstein model, i.e., the parallel connection of several Hammerstein models having polynomial nonlinearity. Presently an analytical identification method is developed using a chirp excitation signal. Afterward, the parameters of the obtained model have been determined using Finite Element Method analysis. Finally, in order to show the effectiveness of the proposed method, a comparison between the true and estimate models has been performed. The obtained results show that the output responses are very close.

Keywords: switched reluctance motor, swept-sine signal, generalized Hammerstein model, nonlinear system

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Authors: M.A. Ali, M. Matloob, A. Sahar, M. Yamin, M. Imran, Y.A. Yusof

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Quinoa (Chenopodium quinoa Willd.) is known as pseudocereal was originated in South America's Andes. Quinoa is a good source of protein, amino acids, micronutrients and bioactive components. The lack of gluten makes it suitable for celiac patients. Saponins, the leading ant-nutrient, are found in the pericarp, which adheres to the seed and transmits the bitter flavor to the quinoa grain. It is found in varying amounts in quinoa from 0.1% to 5%. This study was planned to design an indigenous machine to remove saponin from quinoa grains at the farm level to promote entrepreneurship. The machine consisted of a feeding hopper, rotating shaft, grooved stone, perforated steel cylinder, V-belts, pulleys, electric motor and mild steel angle iron and sheets. The motor transmitted power to the shaft with a belt drive. The shaft on which the grooved stone was attached rotated inside the perforated cylinder having a clearance of 2 mm and was removed saponin by an abrasion mechanism. The saponin-removed quinoa was then dipped in water to determine the presence of saponin as it produced foam in water and data were statistically analyzed. The results showed that the raw seed feeding rate of 25 g/s and milling time of 135 s completely removed saponin from seeds with minimum grain losses of 2.85% as compared to the economic analysis of the machine showed that its break-even point was achieved after one and half months with 18,000 s and a production capacity of 33 g/s.

Keywords: quinoa seeds, saponin, abrasion mechanism, stone polishing, indigenous machine

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Authors: S. B. Rathna Kumar, Sandya K. Varudhini, Aparna Ravichandran

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Telugu is a south central Dravidian language spoken in Andhra Pradesh, a southern state of India. The available speech identification tests in Telugu have been developed to determine the communication problems of individuals having a flat frequency hearing loss. These conventional speech audiometric tests would provide redundant information when used on individuals with high-frequency sloping hearing loss because of better hearing sensitivity in the low- and mid-frequency regions. Hence, conventional speech identification tests do not indicate the true nature of the communication problem of individuals with high-frequency sloping hearing loss. It is highly possible that a person with a high-frequency sloping hearing loss may get maximum scores if conventional speech identification tests are used. Hence, there is a need to develop speech identification test materials that are specifically designed to assess the speech identification performance of individuals with high-frequency sloping hearing loss. The present study aimed to develop speech identification test for individuals with high-frequency sloping hearing loss in Telugu. Individuals with high-frequency sloping hearing loss have difficulty in perception of voiceless consonants whose spectral energy is above 1000 Hz. Hence, the word lists constructed with phonemes having mid- and high-frequency spectral energy will estimate speech identification performance better for such individuals. The phonemes /k/, /g/, /c/, /ṭ/ /t/, /p/, /s/, /ś/, /ṣ/ and /h/are preferred for the construction of words as these phonemes have spectral energy distributed in the frequencies above 1000 KHz predominantly. The present study developed two word lists in Telugu (each word list contained 25 words) for evaluating speech identification performance of individuals with high-frequency sloping hearing loss. The performance of individuals with high-frequency sloping hearing loss was evaluated using both conventional and high-frequency word lists under recorded voice condition. The results revealed that the developed word lists were found to be more sensitive in identifying the true nature of the communication problem of individuals with high-frequency sloping hearing loss.

Keywords: speech identification test, high-frequency sloping hearing loss, recorded voice condition, Telugu

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Authors: H. Majour, L. Djabri

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Many methods in the groundwater vulnerability have been developed in the world (methods like PRAST, DRIST, APRON/ARAA, PRASTCHIM, GOD). In this study, our choice dealt with two recent complementary methods using category mapping of index with weighting criteria (Point County Systems Model MSCP) namely the standard DRASTIC method and SI (Susceptibility Index). At present, these two methods are the most used for the mapping of the intrinsic vulnerability of groundwater. Two classes of groundwater vulnerability in the Biskra sandy aquifer were identified by the DRASTIC method (average and high) and the SI method (very high and high). Integrated analysis has revealed that the high class is predominant for the DRASTIC method whereas for that of SI the preponderance is for the very high class. Furthermore, we notice that the method SI estimates better the vulnerability for the pollution in nitrates, with a rate of 85 % between the concentrations in nitrates of groundwater and the various established classes of vulnerability, against 75 % for the DRASTIC method. By including the land use parameter, the SI method produced more realistic results.

Keywords: DRASTIC, SI, GIS, Biskra sandy aquifer, Algeria

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Authors: Sezer Kefeli, Sertaç Arslan

Abstract:

Supercavitation is a pressure dependent process which gives opportunity to eliminate the wetted surface effects on the underwater vehicle due to the differences of viscosity and velocity effects between liquid (freestream) and gas phase. Cavitation process occurs depending on rapid pressure drop or temperature rising in liquid phase. In this paper, pressure based cavitation is investigated due to the fact that is encountered in the underwater world, generally. Basically, this vapor-filled pressure based cavities are unstable and harmful for any underwater vehicle because these cavities (bubbles or voids) lead to intense shock waves while collapsing. On the other hand, supercavitation is a desired and stabilized phenomena than general pressure based cavitation. Supercavitation phenomena offers the idea of minimizing form drag, and thus supercavitating vehicles are revived. When proper circumstances are set up, which are either increasing the operating speed of the underwater vehicle or decreasing the pressure difference between free stream and artificial pressure, the continuity of the supercavitation is obtainable. There are 2 types of supercavitation to obtain stable and continuous supercavitation, and these are called as natural and artificial supercavitation. In order to generate natural supercavitation, various mechanical structures are discovered, which are called as cavitators. In literature, a lot of cavitator types are studied either experimentally or numerically on a CFD platforms with intent to observe natural supercavitation since the 1900s. In this paper, firstly, experimental results are obtained, and trend lines are generated based on supercavitation parameters in terms of cavitation number (), form drag coefficientC_D, dimensionless cavity diameter (d_m/d_c), and length (L_c/d_c). After that, natural cavitation verification studies are carried out for disk and cone shape cavitators. In addition, supercavitation parameters are numerically analyzed at different operating conditions, and CFD results are fitted into trend lines of experimental results. The aims of this paper are to generate one generally accepted drag coefficient equation for disk and cone cavitators at different cavitator half angle and investigation of the supercavitation parameters with respect to cavitation number. Moreover, 165 CFD analysis are performed at different cavitation numbers on FLUENT version 21R2. Five different cavitator types are modeled on SCDM with respect tocavitator’s half angles. After that, CFD database is generated depending on numerical results, and new trend lines are generated based on supercavitation parameters. These trend lines are compared with experimental results. Finally, the generally accepted drag coefficient equation and equations of supercavitation parameters are generated.

Keywords: cavity envelope, CFD, high speed underwater vehicles, supercavitation, supercavitating flows, supercavitation parameters, drag reduction, viscous force elimination, natural cavitation verification

Procedia PDF Downloads 131

Authors: Sri Sharath Kulkarni, Pauline Janssen, Alberto Berardi, Bastiaan Dickhoff, Sander van Gessel

Abstract:

Blending is a common process in the production of pharmaceutical dosage forms where the high shear is used to obtain a homogenous dosage. The shear required can lead to uncontrolled attrition of excipients and affect API’s. This has an impact on the performance of the formulation as this can alter the structure of the mixture. Therefore, it is important to understand the driving mechanisms for attrition. The aim of this study was to increase the fundamental understanding of the attrition behavior of excipients. Attrition behavior of the excipients was evaluated using a high shear blender (Procept Form-8, Zele, Belgium). Twelve pure excipients are tested, with morphologies varying from crystalline (sieved), granulated to spray dried (round to fibrous). Furthermore, materials include lactose, microcrystalline cellulose (MCC), di-calcium phosphate (DCP), and mannitol. The rotational speed of the blender was set at 1370 rpm to have the highest shear with a Froude (Fr) number 9. Varying blending times of 2-10 min were used. Subsequently, after blending, the excipients were analyzed for changes in particle size distribution (PSD). This was determined (n = 3) by dry laser diffraction (Helos/KR, Sympatec, Germany). Attrition was found to be a surface phenomenon which occurs in the first minutes of the high shear blending process. An increase of blending time above 2 mins showed no change in particle size distribution. Material chemistry was identified as a key driver for differences in the attrition behavior between different excipients. This is mainly related to the proneness to fragmentation, which is known to be higher for materials such as DCP and mannitol compared to lactose and MCC. Secondly, morphology also was identified as a driver of the degree of attrition. Granular products consisting of irregular surfaces showed the highest reduction in particle size. This is due to the weak solid bonds created between the primary particles during the granulation process. Granular DCP and mannitol show a reduction of 80-90% in x10(µm) compared to a 20-30% drop for granular lactose (monohydrate and anhydrous). Apart from the granular lactose, all the remaining morphologies of lactose (spray dried-round, sieved-tomahawk, milled) show little change in particle size. Similar observations have been made for spray-dried fibrous MCC. All these morphologies have little irregular or sharp surfaces and thereby are less prone to fragmentation. Therefore, products containing brittle materials such as mannitol and DCP are more prone to fragmentation when exposed to shear. Granular products with irregular surfaces lead to an increase in attrition. While spherical, crystalline, or fibrous morphologies show reduced impact during high shear blending. These changes in size will affect the functionality attributes of the formulation, such as flow, API homogeneity, tableting, formation of dust, etc. Hence it is important for formulators to fully understand the excipients to make the right choices.

Keywords: attrition, blending, continuous manufacturing, excipients, lactose, microcrystalline cellulose, shear

Procedia PDF Downloads 112

Authors: Yousef Almutairi, Yajue Wu

Abstract:

Various large-scale trends have characterized the current century thus far, including increasing shifts towards urbanization and greater movement. It is predicted that there will be 9.3 billion people on Earth in 2050 and that over two-thirds of this population will be city dwellers. Moreover, in larger cities worldwide, mass transportation systems, including underground systems, have grown to account for the majority of travel in those settings. Underground networks are vulnerable to fires, however, endangering travellers’ safety, with various examples of fire outbreaks in this setting. This study aims to increase knowledge of the impacts of extreme climatic conditions on fires, including the role of the high ambient temperatures experienced in Middle Eastern countries and specifically in Saudi Arabia. This is an element that is not always included when assessments of fire safety are made (considering visibility, temperatures, and flows of smoke). This paper focuses on a tunnel within Riyadh’s underground system as a case study and includes simulations based on computational fluid dynamics using ANSYS Fluent, which investigates the impact of various ventilation systems while identifying smoke density, speed, pressure and temperatures within this tunnel.

Keywords: fire, subway tunnel, CFD, mechanical ventilation, smoke, temperature, harsh weather

Procedia PDF Downloads 132

Authors: Hamidreza Ghazvinian, Khosro Ghazvinian, Touba Khodaiean

Abstract:

The importance of evaporation estimation in water resources and agricultural studies is undeniable. Pan evaporation are used as an indicator to determine the evaporation of lakes and reservoirs around the world due to the ease of interpreting its data. In this research, intelligent models were investigated in estimating pan evaporation on a daily basis. Shahroud and Mayamey were considered as the studied cities. These two cities are located in Semnan province in Iran. The mentioned cities have dry weather conditions that are susceptible to high evaporation potential. Meteorological data of 11 years of synoptic stations of Shahrood and Mayamey cities were used. The intelligent models used in this study are Artificial Neural Network (ANN), Least Squares Support Vector Machine (LSSVM), and M5 tree models. Meteorological parameters of minimum and maximum air temperature (Tmax, Tmin), wind speed (WS), sunshine hours (SH), air pressure (PA), relative humidity (RH) as selected input data and evaporation data from pan (EP) to The output data was considered. 70% of data is used at the education level, and 30 % of the data is used at the test level. Models used with explanation coefficient evaluation (R2) Root of Mean Squares Error (RMSE) and Mean Absolute Error (MAE). The results for the two Shahroud and Mayamey stations showed that the above three models' operations are rather appropriate.

Keywords: pan evaporation, intelligent methods, shahroud, mayamey

Procedia PDF Downloads 74

Authors: Javier Paul Montalvo Andia, Adriana Larrea Valdivia, Adolfo Pillihuaman Zambrano

Abstract:

The most common lixiviant in the leaching process of copper minerals is H₂SO₄, however, the current situation requires more environmentally friendly reagents and in certain situations that have a lower consumption due to the presence of undesirable gangue as muscovite or kaolinite that can make the process unfeasible. The present work studied the leaching of an oxidized copper mineral in an aqueous solution of ammonium nitrate, in order to obtain the optimum leaching conditions of the copper contained in the malachite mineral from Peru. The copper ore studied comes from a deposit in southern Peru and was characterized by X-ray diffractometer, inductively coupled-plasma emission spectrometer (ICP-OES) and atomic absorption spectrophotometry (AAS). The experiments were developed in batch reactor of 600 mL where the parameters as; temperature, pH, ammonium nitrate concentration, particle size and stirring speed were controlled according to experimental planning. The sample solution was analyzed for copper by atomic absorption spectrophotometry (AAS). A simulation in the HSC Chemistry 6.0 program showed that the predominance of the copper compounds of a Cu-H₂O aqueous system is altered by the presence in the system of ammonium complexes, the compound being thermodynamically more stable Cu(NH3)₄²⁺, which predominates in pH ranges from 8.5 to 10 at a temperature of 25 °C. The optimum conditions for copper leaching of the malachite mineral were a stirring speed of 600 rpm, an ammonium nitrate concentration of 4M, a particle diameter of 53 um and temperature of 62 °C. These results showed that the leaching of copper increases with increasing concentration of the ammonium solution, increasing the stirring rate, increasing the temperature and decreasing the particle diameter. Finally, the recovery of copper in optimum conditions was above 80%.

Keywords: ammonium nitrate, malachite, copper oxide, leaching

Procedia PDF Downloads 189

Authors: Amin Nezarat, Naeime Seifadini

Abstract:

Trip mode selection is a behavioral characteristic of passengers with immense importance for travel demand analysis, transportation planning, and traffic management. Identification of trip mode distribution will allow transportation authorities to adopt appropriate strategies to reduce travel time, traffic and air pollution. The majority of existing trip mode inference models operate based on human selected features and traditional machine learning algorithms. However, human selected features are sensitive to changes in traffic and environmental conditions and susceptible to personal biases, which can make them inefficient. One way to overcome these problems is to use neural networks capable of extracting high-level features from raw input. In this study, the convolutional neural network (CNN) architecture is used to predict the trip mode distribution based on raw GPS trajectory data. The key innovation of this paper is the design of the layout of the input layer of CNN as well as normalization operation, in a way that is not only compatible with the CNN architecture but can also represent the fundamental features of motion including speed, acceleration, jerk, and Bearing rate. The highest prediction accuracy achieved with the proposed configuration for the convolutional neural network with batch normalization is 85.26%.

Keywords: predicting, deep learning, neural network, urban trip

Procedia PDF Downloads 138

Authors: Ki-Jin Kim, Suk-Hui LEE, Sanghoon Park, K. H. Ahn

Abstract:

A high power, low loss asymmetric single pole double through(SPDT) antenna switch for LTE-A Front-End Module(FEM) is presented in this paper by using CMOS technology. For the usage of LTE-A applications, low loss and high linearity are the key features which are very challenging works under CMOS process. To enhance insertion loss(IL) and power handling capability, this paper adopts asymmetric Transmitter (TX) and RX (Receiver) structure, floating body technique, multi-stacked structure, and feed forward capacitor technique. The designed SPDT switch shows TX IL 0.34 dB, RX IL 0.73 dB, P1dB 38.9 dBm at 0.9 GHz and TX IL 0.37 dB, RX IL 0.95 dB, P1dB 39.1 dBm at 2.5 GHz respectively.

Keywords: CMOS switch, SPDT switch, high power CMOS switch, LTE-A FEM

Procedia PDF Downloads 364

Authors: P. Serpytis, K. Azukaitis, U. Gargalskaite, R. Navickas, J. Badariene, V. Dzenkeviciute

Abstract:

Purpose: Total longitudinal displacement (tLoD) of the common carotid artery (CCA) wall is a novel ultrasound marker of vascular function that can be evaluated using modified speckle tracking techniques. Decreased CCA tLoD has already been shown to be associated with diabetes and was shown to predict one year cardiovascular outcome in patients with suspected coronary artery disease (CAD) . The aim of our study was to evaluate if CCA tLoD differ between patients with moderate or high cardiovascular (CV) risk and patients after recent acute myocardial infarction (AMI). Methods: 49 patients (54±6 years) with moderate or high CV risk and 42 patients (58±7 years) after recent AMI were included. All patients were non-diabetic. CCA tLoD was evaluated using GE EchoPAC speckle tracking software and expressed as mean of both sides. Data on systolic blood pressure, total and high density lipoprotein (HDL) cholesterol levels, high sensitivity C-reactive protein (hsCRP) level, smoking status and family history of early CV events was evaluated and assessed for association with CCA tLoD. Results: tLoD of CCA did not differ between patients with moderate or high CV risk and patients with very high CV risk after MI (0.265±0.128 mm vs. 0.237±0.103 mm, p>0.05). Lower tLoD was associated with lower HDL cholesterol levels (r=0.211, p=0.04) and male sex (0.228±0.1 vs. 0.297±0.134, p=0.01). Conclusions: tLoD of CCA did not differ between patients with moderate or high CV risk and patients with very high CV risk after AMI. However, lower CCA tLoD was significantly associated with low HDL cholesterol levels and male sex.

Keywords: total longitudinal displacement, carotid artery, cardiovascular risk, acute myocardial infarction

Procedia PDF Downloads 384

Authors: Samia Hachemi, Abdelhafid Ounis, W. Heriheri

Abstract:

This paper presents an experimental investigation of high temperatures applied to normal and high performance concrete made with natural coarse aggregates. The experimental results of physical and mechanical properties were compared with those obtained with recycled brick aggregates produced by replacing 30% of natural coarse aggregates by recycled brick aggregates. The following parameters: compressive strength, concrete mass loss, apparent density and water porosity were examined in this experiment. The results show that concrete could be produced by using recycled brick aggregates and reveals that at high temperatures recycled aggregate concrete preformed similar or even better than natural aggregate concrete.

Keywords: high temperature, compressive strength, mass loss, recycled brick aggregate

Procedia PDF Downloads 247

Authors: Yuchen Niu, Liang Zhao, Fangfang Xie, Weiyu Liu

Abstract:

In the past decades, rapid urbanization in China has significantly promoted economic growth and caused a large number of environmental problems. In consideration of land resources shortage, high-density cities will become a common phenomenon in the future. How to improve the living environment under high density is a new challenge. Shenzhen is a typical high-density city, but also the forefront of China's development and reform area. This study selects 9 urban parks with different natural attributes in Shenzhen and explores the relationship of natural, economic, and social conditions within the service scope. Based on correlation analysis and system analysis, the results indicate that improvement of park design and management methods contribute to obtaining higher ecological value and promote economic and social development.

Keywords: correlation analysis, high-density city, park improvement, urban green spaces

Procedia PDF Downloads 129

Authors: Chi-Rung Jiang, Chun-Chung Chen, Sheng-Yuan Shiao, Fang-Yao Yeh

Abstract:

Transmission lines are essential for power systems which play a significant role in a city for the development of infrastructures. Once a tower on the transmission line is damaged or becomes unstable, small-scale transmission tower damage might cause a large-scale electric power failure, and consequently, the enormous economic losses will occur. This paper assesses the structural safety and considers the impact of earthquakes and winds, presents a preliminary study of transmission tower with high-low legs by building structural analysis models of towers. The result shows that the high-low legs towers do have some structural characteristics need to be considered, such as the length of the difference of high legs and low legs should be restricted and the deployment direction of legs must be carefully planned during the design of transmission towers. The outcome of this study is beneficial to power systems authorities.

Keywords: power transition tower, structural analysis, high-low legs, safety assessment

Procedia PDF Downloads 223