Search results for: significant wave height

Authors: Khaled M. Khader, Mamdouh I. Elimy, Omayma A. Nada

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Sustainable development is the nominal goal of most countries at present. In general, fossil fuels are the development mainstay of most world countries. Regrettably, the fossil fuel consumption rate is very high, and the world is facing the problem of conventional fuels depletion soon. In addition, there are many problems of environmental pollution resulting from the emission of harmful gases and vapors during fuel burning. Thus, clean, renewable energy became the main concern of most countries for filling the gap between available energy resources and their growing needs. There are many renewable energy sources such as wind, solar and wave energy. Energy can be obtained from the motion of sea waves almost all the time. However, power generation from solar or wind energy is highly restricted to sunny periods or the availability of suitable wind speeds. Moreover, energy produced from sea wave motion is one of the cheapest types of clean energy. In addition, renewable energy usage of sea waves guarantees safe environmental conditions. Cheap electricity can be generated from wave energy using different systems such as oscillating bodies' system, pendulum gate system, ocean wave dragon system and oscillating water column device. In this paper, a multi-criteria model has been developed using Analytic Hierarchy Process (AHP) to support the decision of selecting the most effective system for generating power from sea waves. This paper provides a widespread overview of the different design alternatives for sea wave energy converter systems. The considered design alternatives have been evaluated using the developed AHP model. The multi-criteria assessment reveals that the off-shore Oscillating Water Column (OWC) system is the most appropriate system for generating power from sea waves. The OWC system consists of a suitable hollow chamber at the shore which is completely closed except at its base which has an open area for gathering moving sea waves. Sea wave's motion pushes the air up and down passing through a suitable well turbine for generating power. Improving the power generation capability of the OWC system is one of the main objectives of this research. After investigating the effect of some design modifications, it has been concluded that selecting the appropriate settings of some effective design parameters such as the number of layers of Wells turbine fans and the intermediate distance between the fans can result in significant improvements. Moreover, simple dynamic analysis of the Wells turbine is introduced. Furthermore, this paper strives for comparing the theoretical and experimental results of the built experimental prototype.

Keywords: renewable energy, oscillating water column, multi-criteria selection, Wells turbine

Procedia PDF Downloads 152

Authors: Seungwon Baek, Haeseok Jeong, Haehyun Lee, Woojin Park

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The main purpose of this study was to compare obese people to the non-obese in terms of joint kinematics in lower-limb body. The height of chairs was also considered as a design factor. Obese people had a difficulty in sit-to-stand (STS) tasks compared to the non-obese people. High chair heights can make STS task easy and it helps the obese to be more comfortable with STS task in particular. Subjects were instructed to wear inertial measurement unit (IMU) sensors. They perform STS task using chairs of different heights. Joint kinematics and subjective ratings of discomfort were measured. Knee angles of the obese group were greater than that of the non-obese group in normal type. No significant difference in joint kinematics was found in high chair. Interaction effect was found between obesity and height of chair. The results verified the previous research that had suggested a biomechanical model of STS movement. The results can be applied to occupational design for the obese.

Keywords: biomechanics, electromyography, joint kinematics, obesity, sitting, sit-to-stand

Procedia PDF Downloads 293

Authors: Ahmed Assem Abd El Rahim

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Background: Mechanical low back pain is serious physical and social health problem. Purpose: To examine impact of shock wave therapy versus intermittent mechanical traction on mechanical LBP, and disabilities. Subjects: 60 mechanical LBP male studied cases years old 20-35 years were assigned randomly into 3 groups, Picked up from Sohag university orthopedic hospital outpatient clinic. Methods: (Study Group) A: 20 studied cases underwent shock wave therapy plus conventional physical therapy. (Study Group) B: twenty studied cases underwent intermittent mechanical traction plus conventional physical therapy. (Control Group) C: 20 patients underwent conventional physical therapy alone. Three sessions were applied weekly for four weeks. Pain was quantified using McGill Pain Questionnaire, Roland Morris Disability Questionnaire was used for measuring disability, and the ROM was evaluated by (BROM) device pre- & post-therapy. Results: Groups (A, B & C) found a reduction in pain & disability & rise in their in flexion and extension ROM after end of 4 weeks of program. Mean values of pain scale after therapy were 15.3, 9.47, and 23.07 in groups A, B, & C. mean values of Disability scale after therapy were 8.44, 4.87, 11.8in groups A, B & C. mean values of ROM of flexion were 25.53, 29.06, & 23.9 in groups A, B & C. mean values of ROM of extension were 11.73, 15.53 & 9.85 in groups A, B & C. studied cases who received intermittent mechanical traction & conventional physical therapy (group B), found reduction in pain & disability & improvement in ROM of flexion & extension value (P<0.001) after therapy program. Conclusion: Shock wave therapy and intermittent mechanical traction, as well as conventional physical treatment, can be beneficial in studied cases with mechanical LBP.

Keywords: mechanical low back pain, shock wave, mechanical, low back pain

Procedia PDF Downloads 45

Authors: Areej Javaid, Nishat Fatima, Mehwish Naseer

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There is a tremendous use of biofertilizers in agriculture to increase crop productivity. Pakistan spends a huge amount on the purchase of synthetic fertilizers every year. The use of natural compounds to harness crop productivity is the major area of interest nowadays due to being safe for human health and the environment as well. Legumes have the intrinsic quality to enrich the nutrient status of soil because of the presence of nitrogen fixation bacteria on nodules. This research determined the effect of biofertilizer on nodulation attributes and yield of the pea plant. Seeds of pea varieties were treated with a slurry of biofertilizer prepared in a 10% sugar solution just before seed sowing. The impact of biofertilizer on different parameters of growth, yield and nodulation was observed. Analysis of variance showed that plant height, days to flowering, number of nodes, days to first pod, root length and plant height exhibited significant genetic variation. All the yield parameters, including the number of pods per plant, number of seeds per pod, seed fresh and dry weight showed significant results under treatment. Among nodulation parameters, nodule number responded positively to biofertilizer treatment. Genotypes 2001-40 showed better performance followed by 2001-20 and LINA-PAK in all the parameters, whereas 2001-40 and 2001-20 performed well in nodulation and yield parameters. Consequently, seed treatment with biofertilizer before sowing is recommended to obtain higher crop yield.

Keywords: biological nitrogen fixation, correlation analysis, quantitative inheritance, varietal responses

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Authors: Hasan Dalgic, Fikret Akinerdem

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This trial was made to determine effect of different plant density and weed control on yield and quality of winter sowing safflower (Carthamus tinctorius L.) in Selcuk University, Agricultural Faculty trial fields and the effective substance of Trifluran was used as herbicide. Field trial was made during the vegetation period of 2009-2010 with three replications according to 'Split Plots in Randomized Blocks' design. The weed control techniques were made on main plots and row distances was set up on sub-plots. The trial subjects were consisting from three weed control techniques as fallowing: herbicide application (Trifluran), hoeing and control beside the row distances of 15 cm and 30 cm. The results were ranged between 59.0-76.73 cm in plant height, 40.00-47.07 cm in first branch height, 5.00-7.20 in number of branch per plant, 6.00-14.73 number of head per plant, 19.57-21.87 mm in head diameter, 2125.0-3968.3 kg ha-1 in seed yield, 27.10-28.08 % in crude oil rate and 531.7-1070.3 kg ha-1. According to the results, Remzibey safflower cultivar showed the highest seed yield on 30 cm of row distance and herbicide application by means of the direct effects of plant height, first branch height, number of branch per plant, number of head per plant, table diameter, crude oil rate and crude oil yield.

Keywords: safflower, herbicide, row spacing, seed yield, oil ratio, oil yield

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Authors: Mark Watson, J.-F. Bousquet, Adam Forget

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A magnetic induction based underwater communication link is evaluated using an analytical model and a custom Finite-Difference Time-Domain (FDTD) simulation tool. The analytical model is based on the Sommerfeld integral, and a full-wave simulation tool evaluates Maxwell’s equations using the FDTD method in cylindrical coordinates. The analytical model and FDTD simulation tool are then compared and used to predict the system performance for various transmitter depths and optimum frequencies of operation. To this end, the system bandwidth, signal to noise ratio, and the magnitude of the induced voltage are used to estimate the expected channel capacity. The models show that in seawater, a relatively low-power and small coils may be capable of obtaining a throughput of 40 to 300 kbps, for the case where a transmitter is at depths of 1 to 3 m and a receiver is at a height of 1 m.

Keywords: magnetic induction, FDTD, underwater communication, Sommerfeld

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Authors: João Madureira, Ricardo Lagido, Inês Sousa, Fraunhofer Portugal

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Surf is an increasingly popular sport and its performance evaluation is often qualitative. This work aims at using a smartphone to collect and analyze the GPS and inertial sensors data in order to obtain quantitative metrics of the surfing performance. Two approaches are compared for detection of wave rides, computing the number of waves rode in a surfing session, the starting time of each wave and its duration. The first approach is based on computing the velocity from the Global Positioning System (GPS) signal and finding the velocity thresholds that allow identifying the start and end of each wave ride. The second approach adds information from the Inertial Measurement Unit (IMU) of the smartphone, to the velocity thresholds obtained from the GPS unit, to determine the start and end of each wave ride. The two methods were evaluated using GPS and IMU data from two surfing sessions and validated with similar metrics extracted from video data collected from the beach. The second method, combining GPS and IMU data, was found to be more accurate in determining the number of waves, start time and duration. This paper shows that it is feasible to use smartphones for quantification of performance metrics during surfing. In particular, detection of the waves rode and their duration can be accurately determined using the smartphone GPS and IMU.

Keywords: inertial measurement unit (IMU), global positioning system (GPS), smartphone, surfing performance

Procedia PDF Downloads 392

Authors: V. Khosravi, F. D. Ardejani, A. Aryafar, M. Sedighi

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Heavy metals have a damaging impact for the environment, animals and humans due to their extreme toxicity and removing them from wastewaters is a very important and interesting task in the field of water pollution control. Biosorption is a relatively new method for treatment of wastewaters and recovery of heavy metals. In this study, a continuous fixed bed study was carried out by using Bacillus thuringiensis as a biosorbent for the removal of Cu and Mn ions from Sarcheshmeh Acid Mine Drainage (AMD). The effect of operating parameters such as flow rate and bed height on the sorption characteristics of B. thuringiensis was investigated at pH 6.0 for each metal ion. The experimental results showed that the breakthrough time decreased with increasing flow rate and decreasing bed height. The data also indicated that the equilibrium uptake of both metals increased with decreasing flow rate and increasing bed height. BDST, Thomas, and Yoon–Nelson models were applied to experimental data to predict the breakthrough curves. All models were found suitable for describing the whole dynamic behavior of the column with respect to flow rate and bed height. In order to regenerate the adsorbent, an elution step was carried out with 1 M HCl and five adsorption-desorption cycles were carried out in continuous manner.

Keywords: acid mine drainage, bacillus thuringiensis, biosorption, cu and mn ions, fixed bed

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Authors: Samet Sen, Yalcin Alver

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Before Izmir Commuter Rail System (IZBAN), most of the respondents along the railway were making their trips by city buses, minibuses or private cars. After IZBAN was put into service, some people changed their previous trip behaviors and they started travelling by IZBAN. Therefore a big travel demand in IZBAN occurred. In this study, the characteristics of passengers and their trip behaviors are found out based on the longitudinal data conducted via two wave trip surveys. Just after one year from IZBAN's opening, the first wave of the surveys was carried out among 539 passengers at six stations during morning peak hours between 07.00 am-09.30 am. The second wave was carried out among 669 passengers at the same six stations two years after the first wave during the same morning peak hours. As a result of this study, the respondents' socio-economic specifications, the distribution of trips by region, the impact of IZBAN on transport modes, the changes in travel time and travel cost and satisfaction data were obtained. These data enabled to compare two waves and explain the changes in socio-economic factors and trip behaviors. In both waves, 10 % of the respondents stopped driving their own cars and they started to take IZBAN. This is an important development in solving traffic problems. More public transportation means less traffic congestion.

Keywords: commuter rail system, comparative study, longitudinal survey, public transportation

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Authors: A. Nurgiartiningsih, G. Ciptadi, S. B. Siswijono

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This research was done to identify the performance and breeding potency of Local Buffalo in Kangean Island, Sumenep, East Java, Indonesia. Materials used were buffalo and farmer in Kangean Island. Method used was survey with purposive sampling method. Qualitative trait and existing breeding system including the type of production system were directly observed. Quantitative trait consisted of chest girth, body weight and wither height were measured and recorded. Data were analyzed using analysis of variance applying software GENSTAT 14. Results showed the purposes of buffalo breeding in Kangean Island were for production of calves, saving, religion tradition, and buffalo racing. The combination between grazing and cut and carry system were applied in Kangean Island. Forage, grass and agricultural waste product were available abundantly especially, during the wet season. Buffalo in Kangean Island was categorized as swamp buffalo with 48 chromosomes. Observation on qualitative trait indicated that there were three skin color types: gray (81.25%), red (10.42%) and white/albino (8.33%). Analysis on quantitative trait showed that there was no significant difference between male and female buffalo. The performance of male buffalo was 132.56 cm, 119.33 cm and 174.11 cm, for the mean of body length, whither height and chest girth, respectively. The performance of female buffalo were 129.8 cm, 114.0 cm and 166.2 cm, for mean of body length, wither height and chest girth (CG), respectively. The performance of local buffalo in Kangean Island was categorized well. Kangean Island could be promoted as center of buffalo breeding and conservation. For optimal improvement of population number and its genetics value, government policy in buffalo breeding program should be implemented.

Keywords: chromosome, qualitative trait, quantitative trait, swamp buffalo

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Authors: Yogendra K. Karna, Lauren T. Bennett

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Fire-tolerant eucalypt forests are one of the major forest ecosystems of south-eastern Australia and thought to be highly resistant to frequent high severity wildfires. However, the impact of different severity wildfires on the canopy structure of fire-tolerant forest type is under-studied, and there are significant knowledge gaps in relation to the assessment of tree and stand level canopy structural dynamics and recovery after fire. Assessment of canopy structure is a complex task involving accurate measurements of the horizontal and vertical arrangement of the canopy in space and time. This study examined the utility of multitemporal, small-footprint lidar data to describe the changes in the horizontal and vertical canopy structure of fire-tolerant eucalypt forests seven years after wildfire of different severities from the tree to stand level. Extensive ground measurements were carried out in four severity classes to describe and validate canopy cover and height metrics as they change after wildfire. Several metrics such as crown height and width, crown base height and clumpiness of crown were assessed at tree and stand level using several individual tree top detection and measurement algorithm. Persistent effects of high severity fire 8 years after both on tree crowns and stand canopy were observed. High severity fire increased the crown depth but decreased the crown projective cover leading to more open canopy.

Keywords: canopy gaps, canopy structure, crown architecture, crown projective cover, multi-temporal lidar, wildfire severity

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Authors: Chinsuk Hong

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This paper investigates the characteristics of wall pressure fluctuations in naturally developing boundary layer flows on axisymmetric bodies experimentally. The axisymmetric body has a modified ellipsoidal blunt nose. Flush-mounted microphones are used to measure the wall pressure fluctuations in the boundary layer flow over the body. The measurements are performed in a low noise wind tunnel. It is found that the correlation between the flow regime and the characteristics of the pressure fluctuations is distinct. The process from small fluctuation in laminar flow to large fluctuation in turbulent flow is investigated. Tollmien-Schlichting wave (T-S wave) is found to generate and develop in transition. Because of the T-S wave, the wall pressure fluctuations in the transition region are higher than those in the turbulent boundary layer.

Keywords: wall pressure fluctuation, boundary layer flow, transition, turbulent flow, axisymmetric body, flow noise

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Authors: Joseph Christopher R. Ragasa, Paolo Gabriel P. Casas, Nemesio S. Mangila, Maria Emma C. Villamin, Myra G. Bungag

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A procedure in measuring the thermal protrusion profiles of magnetic recording heads was developed using a Wyko HD-8100 optical interference-based instrument. The protrusions in the heads were made by the application of a constant power through the thermal flying height controller pads. It was found that the thermally-induced bubble is confined to form in the same head locations, primarily in the reader and writer regions, regardless of the direction of approach of temperature. An application of power to the thermal flying height control pads ranging from 0 to 50 milliWatts showed that the protrusions demonstrate a linear dependence with the supplied power. The efficiencies calculated using this method were compared to that obtained through Guzik and found to be 19.57% greater due to the static testing environment used in the testing.

Keywords: thermal protrusion profile, magnetic recording heads, wyko interferometry, thermal flying height control

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Authors: Lotfi O. Gargab, Ruichong R. Zhang

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A wave-based framework is presented for modeling seismic motion in multistory buildings and using measured response for system identification which can be utilized to extract important information regarding structure integrity. With one pair of building response at two locations, a generalized model response is formulated based on wave propagation features and expressed as frequency and time response functions denoted, respectively, as GFRF and GIRF. In particular, GIRF is fundamental in tracking arrival times of impulsive wave motion initiated at response level which is dependent on local model properties. Matching model and measured-structure responses can help in identifying model parameters and infer building properties. To show the effectiveness of this approach, the Millikan Library in Pasadena, California is identified with recordings of the Yorba Linda earthquake of September 3, 2002.

Keywords: system identification, continuous-discrete mass modeling, damage detection, post-earthquake

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Authors: A. H. Choudhury

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In this paper, a highly accurate numerical method for the solution of one-dimensional fourth-order wave equation is derived. This hyperbolic problem is solved by using semidiscrete approximations. The space direction is discretized by wavelet-Galerkin method, and the time variable is discretized by using Newmark schemes.

Keywords: hyperbolic problem, semidiscrete approximations, stability, Wavelet-Galerkin Method

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Authors: Michał Lidner, Zbigniew SzcześNiak

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The ability to estimate blast load overpressure properly plays an important role in safety design of buildings. The issue of studying of blast loading on structural elements has been explored for many years. However, in many literature reports shock wave overpressure is estimated with simplified triangular or exponential distribution in time. This indicates some errors when comparing real and numerical reaction of elements. Nonetheless, it is possible to further improve setting similar to the real blast load overpressure function versus time. The paper presents a method of numerical analysis of the phenomenon of the air shock wave propagation. It uses Finite Volume Method and takes into account energy losses due to a heat transfer with respect to an adiabatic process rule. A system of three equations (conservation of mass, momentum and energy) describes the flow of a volume of gaseous medium in the area remote from building compartments, which can inhibit the movement of gas. For validation three cases of a shock wave flow were analyzed: a free field explosion, an explosion inside a steel insusceptible tube (the 1D case) and an explosion inside insusceptible cube (the 3D case). The results of numerical analysis were compared with the literature reports. Values of impulse, pressure, and its duration were studied. Finally, an overall good convergence of numerical results with experiments was achieved. Also the most important parameters were well reflected. Additionally analyses of dynamic response of one of considered structural element were made.

Keywords: adiabatic process, air shock wave, explosive, finite volume method

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Authors: Won Taek Oh, Adin Richard

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Workers are often required to enter unsupported trenches during the construction process, which may present serious risks. Trench failures can result in death or damage to adjacent properties, therefore trenches should be excavated with extreme precaution. Excavation work is often done in unsaturated soils, where the critical height (i.e. maximum depth that can be excavated without failure) of unsupported trenches can be more reliably estimated by considering the influence of matric suction. In this study, coupled stress/pore-water pressure analyses are conducted to investigate the critical height of sloped unsupported trenches considering the influence of pore-water pressure redistribution caused by excavating. Four different wall slopes (1.5V:1H, 2V:1H, 3V:1H, and 90°) and a vertical trench with the top 0.3 m sloped 1:1 were considered in the analyses with multiple depths of the ground water table in a sand. For comparison, the critical heights were also estimated using the limit equilibrium method for the same excavation scenarios used in the coupled analyses.

Keywords: critical height, matric suction, unsaturated soil, unsupported trench

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Authors: Natarajan Tirupattur Srinivasan

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Quantum mechanics( QM) and (special) relativity (SR) have indeed revolutionized the very thinking of physicists, and the spectacular successes achieved over a century due to these two theories are mind-boggling. However, there is still a strong disquiet among some physicists. While the mathematical structure of these two theories has been established beyond any doubt, their physical interpretations are still being contested by many. Even after a hundred years of their existence, we cannot answer a very simple question, “What is an electron”? Physicists are struggling even now to come to grips with the different interpretations of quantum mechanics with all their ramifications. However, it is indeed strange that the (special) relativity theory of Einstein enjoys many orders of magnitude of “acceptance”, though both theories have their own stocks of weirdness in the results, like time dilation, mass increase with velocity, the collapse of the wave function, quantum jump, tunnelling, etc. Here, in this paper, it would be shown that by postulating an intrinsic internal motion to these enigmatic electrons, one can build a fairly consistent picture of reality, revealing a very simple picture of nature. This is also evidenced by Schrodinger’s ‘Zitterbewegung’ motion, about which so much has been written. This leads to a helical trajectory of electrons when they move in a laboratory frame. It will be shown that the helix is a three-dimensional wave having all the characteristics of our familiar 2D wave. Again, the helix, being a geodesic on an imaginary cylinder, supports ‘quantization’, and its representation is just the complex exponentials matching with the wave function of quantum mechanics. By postulating the instantaneous velocity of the electrons to be always ‘c’, the velocity of light, the entire relativity comes alive, and we can interpret the ‘time dilation’, ‘mass increase with velocity’, etc., in a very simple way. Thus, this model unifies both QM and SR without the need for a counterintuitive postulate of Einstein about the constancy of the velocity of light for all inertial observers. After all, if the motion of an inertial frame cannot affect the velocity of light, the converse that this constant also cannot affect the events in the frame must be true. But entire relativity is about how ‘c’ affects time, length, mass, etc., in different frames.

Keywords: quantum reconstruction, special theory of relativity, quantum mechanics, zitterbewegung, complex wave function, helix, geodesic, Schrodinger’s wave equations

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Authors: L.Jowkar. M.Samiee

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Models or systems based on rainfall and runoff are numerous and have been formulated and applied depending on the precipitation regime, temperature, and climate. In this study, the ArcCN-Runoff rain-runoff modeling tool was used to estimate the spatial variability of the rainfall-runoff relationship in Sartang Ramon in Jiroft watershed. In this study, the runoff was estimated from 6-hour rainfall. The results showed that based on hydrological soil group map, soils with hydrological groups A, B, C, and D covered 1, 2, 55, and 41% of the basin, respectively. Given that the majority of the area has a slope above 60 percent and results of soil hydrologic groups, one can conclude that Sartang Ramon Basin has a relatively high potential for producing runoff. The average runoff height for a 6-hour rainfall with a 2-year return period is 26.6 mm. The volume of runoff from the 2-year return period was calculated as the runoff height of each polygon multiplied by the area of the polygon, which is 137913486 m³ for the whole basin.

Keywords: Arc CN-Run off, rain-runoff, return period, watershed

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Authors: Lu Yang, Meiyang Song, Xiang Yu, Wenhao Zhou, Chuntao Feng

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To address the problem that the FM continuous-wave radar (FMCW) extracts human vital sign signals which are susceptible to noise interference and low reconstruction accuracy, a new detection scheme for the sign signals is proposed. Firstly, an improved complete ensemble empirical modal decomposition with adaptive noise (ICEEMDAN) algorithm is applied to decompose the radar-extracted thoracic signals to obtain several intrinsic modal functions (IMF) with different spatial scales, and then the IMF components are optimized by a BP neural network improved by immune genetic algorithm (IGA). The simulation results show that this scheme can effectively separate the noise and accurately extract the respiratory and heartbeat signals and improve the reconstruction accuracy and signal-to-noise ratio of the sign signals.

Keywords: frequency modulated continuous wave radar, ICEEMDAN, BP neural network, vital signs signal

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Authors: Roger Yu

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A numerical scheme has been developed to solve wave equations for chaotic systems such as stadium-shaped cavity. The same numerical method can also be used for finding wave properties of rectangle cavities with randomly placed obstacles. About 30k eigenvalues have been obtained accurately on a normal circumstance. For comparison, we also initiated an experimental study which determines both eigenfrequencies and eigenfunctions of a stadium-shaped cavity using pulse and normal mode analyzing techniques. The acoustic cavity was made adjustable so that the transition from nonchaotic (circle) to chaotic (stadium) waves can be investigated.

Keywords: quantum dot, chaos, numerical method, eigenvalues

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Authors: M. Mamor

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GaN-based compounds have attracted much interest in the fabrication of high-power, high speed and high-frequency electronic devices. Other examples of GaN-based applications are blue and ultraviolet (UV) light-emitting diodes (LEDs). All these devices require high-quality ohmic and Schottky contacts. Gaining an understanding of the electrical characteristics of metal/GaN contacts is of fundamental and technological importance for developing GaN-based devices. In this work, the barrier characteristics of Pt and Pd Schottky contacts on n-type GaN were studied using temperature-dependent forward current-voltage (I-V) measurements over a wide temperature range 80–400 K. Our results show that the barrier height and ideality factor, extracted from the forward I-V characteristics based on thermionic emission (TE) model, exhibit an abnormal dependence with temperature; i.e., by increasing temperature, the barrier height increases whereas the ideality factor decreases. This abnormal behavior has been explained based on the TE model by considering the presence of double Gaussian distribution (GD) of nonhomogeneous barrier height at the metal/GaN interface. However, in the high-temperature range (160-400 K), the extracted value for the effective Richardson constant A* based on the barrier inhomogeneity (BHi) model is found in fair agreement with the theoretically predicted value of about 26.9 A.cm-2 K-2 for n-type GaN. This result indicates that in this temperature range, the conduction current transport is dominated by the thermionic emission mode. On the other hand, in the lower temperature range (80-160 K), the corresponding effective Richardson constant value according to the BHi model is lower than the theoretical value, suggesting the presence of other current transport, such as tunneling-assisted mode at lower temperatures.

Keywords: Schottky diodes, inhomogeneous barrier height, GaN semiconductors, Schottky barrier heights

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Authors: Ding Yu, Ge Yang, Wang Hong-Tao

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Aiming at the detonation performance and detonation wave propagation distance of liquid fuel detonation engine, the kerosene/oxygen-enriched air mixture is chosen as the research object; its detonation initiation and detonation wave propagation process by mild energy input are numerically studied by using Euler-Lagrange method in the present study. The effects of a semicircular obstacle, rectangular obstacle, and triangular obstacle on the detonation characteristic parameters in the detonation tube are compared and analyzed, and the effect of the angle between obstacle and flame propagation direction on flame propagation characteristics and detonation process when the blocking ratio is constant are studied. The results show that the flame propagation velocity decreases with the increase of the angle in the range of 0-90°, and when the angle is 0° which corresponds to the semicircle obstacle gets the highest detonation wave propagation velocity. With the increase of the angle in the range of 0-90°, DDT (Deflagration to detonation transition) distance decreases first and then increases.

Keywords: deflagration to detonation transition, numerical simulation, obstacle structure, turbulent flame

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Authors: Asmau Mukhtar Ahmed, Olga Duran

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Hydrocarbon (HC) spills constitute a significant problem that causes great concern to the environment. With the latest technology (hyperspectral images) and state of the earth techniques (image processing tools), hydrocarbon spills can easily be detected at an early stage to mitigate the effects caused by such menace. In this study; a controlled laboratory experiment was used, and clay soil was mixed and homogenized with different hydrocarbon types (diesel, bio-diesel, and petrol). The different mixtures were scanned with HYSPEX hyperspectral camera under constant illumination to generate the hypersectral datasets used for this experiment. So far, the Short Wave Infrared Region (SWIR) has been exploited in detecting HC spills with excellent accuracy. However, the Near-Infrared Region (NIR) is somewhat unexplored with regards to HC contamination and how it affects the spectrum of soils. In this study, Deep Neural Network (DNN) was applied to the controlled datasets to detect and quantify the amount of HC spills in soils in the Near-Infrared Region. The initial results are extremely encouraging because it indicates that the DNN was able to identify features of HC in the Near-Infrared Region with a good level of accuracy.

Keywords: hydrocarbon, Deep Neural Network, short wave infrared region, near-infrared region, hyperspectral image

Procedia PDF Downloads 102

Authors: Carla Idely Palencia-Aguilar

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Artificial wetlands play an important role at Guasca Municipality in Colombia, not only because they are used for the agroindustry, but also because more than 45 species were found, some of which are endemic and migratory birds. Remote sensing was used to determine the changes in the area occupied by water of artificial wetlands by means of Aster and Modis images for different time periods. Evapotranspiration was also determined by three methods: Surface Energy Balance System-Su (SEBS) algorithm, Surface Energy Balance- Bastiaanssen (SEBAL) algorithm, and Potential Evapotranspiration- FAO. Empirical equations were also developed to determine the relationship between Normalized Difference Vegetation Index (NDVI) versus net radiation, ambient temperature and rain with an obtained R2 of 0.83. Groundwater level fluctuations on a daily basis were studied as well. Data from a piezometer placed next to the wetland were fitted with rain changes (with two weather stations located at the proximities of the wetlands) by means of multiple regression and time series analysis, the R2 from the calculated and measured values resulted was higher than 0.98. Information from nearby weather stations provided information for ordinary kriging as well as the results for the Digital Elevation Model (DEM) developed by using PCI software. Standard models (exponential, spherical, circular, gaussian, linear) to describe spatial variation were tested. Ordinary Cokriging between height and rain variables were also tested, to determine if the accuracy of the interpolation would increase. The results showed no significant differences giving the fact that the mean result of the spherical function for the rain samples after ordinary kriging was 58.06 and a standard deviation of 18.06. The cokriging using for the variable rain, a spherical function; for height variable, the power function and for the cross variable (rain and height), the spherical function had a mean of 57.58 and a standard deviation of 18.36. Threatens of eutrophication were also studied, given the unconsciousness of neighbours and government deficiency. Water quality was determined over the years; different parameters were studied to determine the chemical characteristics of water. In addition, 600 pesticides were studied by gas and liquid chromatography. Results showed that coliforms, nitrogen, phosphorous and prochloraz were the most significant contaminants.

Keywords: DEM, evapotranspiration, geostatistics, NDVI

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Authors: Jennifer M. Penton

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Record high lake levels in 2017 and 2019 (2017 max lake level = 75.81 m; 2018 max lake level = 75.26 m; 2019 max lake level = 75.92 m) combined with a number of severe storms in the Great Lakes region, have resulted in significant wave generation across Lake Ontario. The resulting large wave heights have led to erosion of the natural shoreline, overtopping of existing revetments, backshore erosion, and partial and complete failure of several coastal structures, which in turn have led to further erosion of the shoreline and damaged existing infrastructure. Such impacts can be seen all along the coast of Lake Ontario. Three specific locations have been chosen as case studies for this paper, each addressing erosion and/or flood mitigation methods, such as revetments and sheet piling with increased land levels. Varying site conditions and the resulting shoreline damage are compared herein. The results are reflected in the case-specific design components of the mitigation and adaptation methods and are presented in this paper.

Keywords: erosion mitigation, flood mitigation, great lakes, high water levels

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Authors: Evangelos Tsakalos, Maria Kazantzaki, Eleni Filippaki, Yannis Bassiakos

Abstract:

The coastal areas of the Mediterranean have been extensively affected by the transgressive event that followed the Last Glacial Maximum, with many studies conducted regarding the stratigraphic configuration of coastal sediments around the Mediterranean. The coastal zone of the Messologi area, western Greece, consists of low relief beaches containing low cliffs and eroded dunes, a fact which, in combination with the rising sea level and tectonic subsidence of the area, has led to substantial coastal. Coastal vulnerability assessment is a useful means of identifying areas of coastline that are vulnerable to impacts of climate change and coastal processes, highlighting potential problem areas. Commonly, coastal vulnerability assessment takes the form of an ‘index’ that quantifies the relative vulnerability along a coastline. Here we make use of the coastal vulnerability index (CVI) methodology by Thieler and Hammar-Klose, by considering geological features, coastal slope, relative sea-level change, shoreline erosion/accretion rates, and mean significant wave height as well as mean tide range to assess the present-day vulnerability of the coastal zone of Messologi area. In light of this, an impact assessment is performed under three different sea level rise scenarios, and adaptation measures to control climate change events are proposed. This study contributes toward coastal zone management practices in low-lying areas that have little data information, assisting decision-makers in adopting best adaptations options to overcome sea level rise impact on vulnerable areas similar to the coastal zone of Messologi.

Keywords: coastal vulnerability index, coastal erosion, sea level rise, GIS

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Authors: F. A. Saracoglu Varol, H. Agaccıoglu

Abstract:

Experimental studies to investigate the depth of the scour conducted at a side-weir intersection located at the 1800 curved flume which located Hydraulic Laboratory of Yıldız Technical University, Istanbul, Turkey. Side weirs were located at the middle of the straight part of the main channel. Three different lengths (25, 40 and 50 cm) and three different weir crest height (7, 10 and 12 cm) of the side weir placed on the side weir station. There is no scour when the material is only kaolin. Therefore, the cohesive bed was prepared by properly mixing clay material (kaolin) with 31% sand in all experiments. Following 24h consolidation time, in order to observe the effect of flow intensity on the scour depth, experiments were carried out for five different upstream Froude numbers in the range of 0.33-0.81. As a result of this study the relation between scour depth and upstream flow intensity as a function of time have been established. The longitudinal velocities decreased along the side weir; towards the downstream due to overflow over the side-weirs. At the beginning, the scour depth increases rapidly with time and then asymptotically approached constant values in all experiments for all side weir dimensions as in non-cohesive sediment. Thus, the scour depth reached equilibrium conditions. Time to equilibrium depends on the approach flow intensity and the dimensions of side weirs. For different heights of the weir crest, dimensionless scour depths increased with increasing upstream Froude number. Equilibrium scour depths which formed 7 cm side-weir crest height were obtained higher than that of the 12 cm side-weir crest height. This means when side-weir crest height increased equilibrium scour depths decreased. Although the upstream side of the scour hole is almost vertical, the downstream side of the hole is inclined.

Keywords: clay-sand mixed sediments, scour, side weir, hydraulic structures

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Authors: Mostafa Mohammadpour, Christoph Kapeller, Christy Li, Josef Scharinger, Christoph Guger

Abstract:

Interictal spikes provide valuable information on electrocorticography (ECoG), which aids in surgical planning for patients who suffer from refractory epilepsy. However, the shape and temporal dynamics of these spikes remain unclear. The purpose of this work was to analyze the shape of interictal spikes and measure their distance to the seizure onset zone (SOZ) to use in epilepsy surgery. Thirteen patients' data from the iEEG portal were retrospectively studied. For analysis, half an hour of ECoG data was used from each patient, with the data being truncated before the onset of a seizure. Spikes were first detected and grouped in a sequence, then clustered into interictal epileptiform discharges (IEDs) and non-IED groups using two-step clustering. The distance of the spikes from IED and non-IED groups to SOZ was quantified and compared using the Wilcoxon rank-sum test. Spikes in the IED group tended to be in SOZ or close to it, while spikes in the non-IED group were in distance of SOZ or non-SOZ area. At the group level, the distribution for sharp wave, positive baseline shift, slow wave, and slow wave to sharp wave ratio was significantly different for IED and non-IED groups. The distance of the IED cluster was 10.00mm and significantly closer to the SOZ than the 17.65mm for non-IEDs. These findings provide insights into the shape and spatiotemporal dynamics of spikes that could influence the network mechanisms underlying refractory epilepsy.

Keywords: spike propagation, spike pattern, clustering, SOZ

Procedia PDF Downloads 51

Authors: Ercan Ceyhan, Ali Kahraman, Hasan Dalgıç

Abstract:

This research was made during the 2011 and 2012 growing periods according to “Randomized Blocks Design” with 3 replications. Research material was the following chickpea genotype: CA119, CA128, CA149, CA150, CA222, CA250, CA254 and other 2 commercial varieties named as Gökçe and Yaşa. Some agronomical characteristics such as plant height (cm), number of pod per plant, number of seed per pod, number of seed per plant, 1000 seed weight (g) and seed yield (kg ha-1) were determined. Statistically significant variations were found amongst the genotypes for all variables except seeds per pod. Means of the two years showed the range for plant height was from 52.83 cm (Gökçe) to 73.00 cm (CA150), number of pod per plant was from 14.00 (CA149) to 26.83 (CA261), number of seed per pod was from 1.10 (Gökçe) to 1.19 (CA149 ve CA250), number of seed per plant was from 16.28 (CA149) to 31.65 (CA261), 1000 seed weight was from 295.85 g (CA149) to 437.80 g (CA261) and seed yield was from 1342.73 kg ha-1 (CA261) to 2161.50 kg ha-1 (CA128). Results of the research implicated that the new developed lines were superior compared with the control (commercial) varieties by means of most of the characteristics.

Keywords: agricultural characters, chickpea, seed yield, genotype variations

Procedia PDF Downloads 203