Horizontal Tracking Research Articles

Performance analyses of Cu–Cl hydrogen production integrated solar parabolic trough collector system under Algerian climate

The potential of hydrogen production by thermochemical cycle in Algeria using solar radiation as heat sources is estimated under the climate conditions of the country. The study analyzes an integrated copper–chlorine (Cu–Cl) thermochemical cycle with solar parabolic trough system for hydrogen production. In order to determine the most promising solar sites available for deploying the integrated system, the direct normal solar irradiance (DNI) for horizontal tracking system oriented in North-South has been estimated and compared for different locations. Heat gain from parabolic trough collector model is evaluated under Algerian conditions. To describe the different steps of the Cu–Cl cycle for hydrogen production, we perform a thermodynamic analysis accounting for relevant chemical reactions and including the determination of the energy necessary to the cycle. A parametric study is conducted to investigate the effect of heat gain from the parabolic trough collector (PTC) on the hydrogen production rate. Furthermore, the rate production of hydrogen by the Cu–Cl cycle is analyzed and compared for performance improvement of the system for different climatic regions in Algeria. Simulation results reveal great opportunities of hydrogen production using Cu–Cl cycle combined with solar PTC in the south of Algeria with annual hydrogen production exceeds 84 Tons H2/year (around 0,30 kg/m2/day).

An impacting linear three body system

We study a system of three identical bodies that can move freely on a horizontal track. Initially one body moves and two are at rest. The moving body impacts with one of the resting bodies which then impacts with the third and so on. The impacts are assumed to be characterised by a coefficient of restitution. We investigate the total number of impacts, the final velocities of the bodies, and the final energy of the system in terms of the initial velocity and the coefficient of restitution. The problem, which originates from mechanics textbooks, can be analysed as a discrete dynamical system with three degrees of freedom. The full solution is more subtle that one might expect.

Optimal design and analysis of grid-connected photovoltaic under different tracking systems using HOMER

This research contributes to the ongoing discussions about the grid-connected solar photovoltaic (PV) systems and draws attention to the optimal design by considering various PV array tracking systems towards enhancing the power generation. The PV tracking system configurations considered in this study include horizontal-axis (monthly adjustment, weekly adjustment, daily adjustment, continuous adjustment), vertical-axis (continuous adjustment), and a two-axis tracking system. HOMER (Hybrid Optimization of Multiple Energy Resources) software is employed whereas the actual data required by the model have been collected in Makkah, Saudi Arabia.The results show that the two-axis tracker can produce 34% more power than the fixed system, while the vertical axis tracker with continuous adjustment was able to generate up to 20% more power than the fixed system. Horizontal tracker with continuous adjustment shows the highest net present cost (NPC) and the highest levelized cost of energy (LCOE), with a high penetration of solar energy to the grid. For the case of Makkah, the vertical axis tracker with continuous adjustment is the best option as it has low LCOE and NPC values with a positive return on investment (ROI) as well as high renewable energy penetration to the grid, which enhances its viability for a utility-size solar PV grid-connected system.

Development of a New Downscale Setup for Wheel-Rail Contact Experiments under Impact Loading Conditions

A new downscale test rig is developed for investigating the contact between the wheel and rail under impact-like loading conditions. This paper presents the development process of the setup, including review and synthesis of the potential experimental techniques, followed by scalability, mechanical and operational analysis of the new setup. The new test rig intends to remedy the lack of dynamic similarity between the actual railway and the existing laboratory testing capability, by taking into account the factors that contribute to high-frequency dynamics of the wheel-track system. The paper first reviews the functionalities of the existing test techniques in the literature. Based on this survey, the category of the scaled wheel on the rail track ring is chosen. Afterwards, three potential alternatives are identified under the chosen category and the optimum mechanism is achieved through finite element modelling and analysis of the structures. A downscale test rig, consisting of multiple wheel components running over a horizontal rail track ring, effectively fulfilled the requirements needed for analogical testing of the wheel-rail contact behaviour. The new test rig is a unique experimental setup due to the involvement of high-frequency dynamic vibrations in the wheel-track system and analogy of the incorporated elements and loading to those of the real-life system. This paper further presents the results of some real experiments carried out using the newly-built setup to support substantial ideas behind its development.

Robust tracking output-control for a quad-rotor: A continuous sliding-mode approach

This paper deals with the problem of robust tracking output-control design for a Quad-Rotor. The proposed approach is based on continuous sliding-modes control (SMC) techniques and it is able to robustly track a desired trajectory for the Quad-Rotor despite some class of disturbances acting on the system. Such a robust tracking control is composed of a finite-time sliding-mode observer (SMO) and cascaded continuous SMCs providing uniform finite-time stability and uniform exponential stability, for the vertical and yaw tracking error, and for the horizontal tracking error, respectively; despite the disturbances on the system, and only using the measurable positions and angles. Simulation results illustrate the feasibility of the proposed tracking strategy.

Numerical simulation of tropical cyclone thane: role of boundary layer and surface drag parameterization schemes

In the recent times, several advanced numerical models are utilized for the prediction of the intensity, track and landfall time of a cyclone. Still there are number of issues concerning their prediction and the limitation of numerical models in addressing those issues. The most pertinent question is how intensive a cyclone can become before it makes a landfall and where the cyclone moves under the ambient large-scale flow. In this paper, detailed study has been carried out using Weather Research Forecast model with two boundary schemes to address the above question by considering a recent tropical cyclone in Bay of Bengal region of North Indian Ocean. In addition, the impact of the surface drag effect on the low-level winds and the intensity of the cyclone are also studied. The result reveals that large differences are noted in the ocean surface fluxes between YSU and MYJ with MYJ producing relatively higher fluxes than YSU. It is found that the YSU scheme produced a better simulation for the THANE cyclone in terms of winds, pressure distribution and cloud fractions. Comparison with available observations indicated the characteristics of horizontal divergence, vorticity and vector track positions produced by YSU experiment are more realistic than with MYJ and other experiments. However, when the drag coefficient is changed as 0.5 or 2.0 from the default values, appreciable changes in the surface fluxes are not noticed. A maximum precipitation is reported in YSU as compared to the MYJ PBL scheme for the tropical cyclone THANE.

Energetic analysis of simplified 2-position and 3-position North-South horizontal single-axis sun tracking concepts

Sun trackers allow the energy yield of photovoltaic systems to be increased. Among the different types of sun tracking strategies, North-South horizontal single-axis sun trackers are of big interest nowadays, especially for their implementation in utility-scale photovoltaic plants. It is important to find concepts which simplify as much as possible these sun trackers. In this paper, an energetic analysis of two very simple tracking strategies, based on a 2-position or 3-position rotatory movement for the North-South horizontal single-axis tracker, is carried out for latitudes up to 50°. The tracker positions (morning/afternoon for 2-positions, or morning/noon/afternoon for 3-positions) change at pre-defined daily schedules and the tilt angle at the morning and afternoon periods is fixed. However, both the daily schedules and the tilt angles can be adjusted in the installation process, to maximize the annual irradiation capture in a given location. Such simple tracking concepts can be implemented without the need of illumination sensors, complex sun position calculations or continuous control of the motion. The energetic analysis was carried out over a set of 22 locations worldwide and the captured irradiation was compared to that of equator-pointed optimally tilted fixed systems and to that of the best energetically efficient North-South horizontal single-axis tracker, i.e. the continuous sun tracker. Results indicate that, depending on the analysed location, the 2-position tracker can provide between 41% and 74%, and the 3-position tracker can provide between 68% and 87% of the annual irradiation gains that the North-South horizontal single-axis continuous sun tracker achieves with respect to an optimally tilted fixed system. Therefore, these types of simplified tracking concepts, especially the 3-position tracker, can be seen asalternatives to existing North-South horizontal single-axis continuous sun trackers, providing significant energy gains with respect to fixed photovoltaic systems.

A Pilot Study of Horizontal Head and Eye Rotations in Baseball Batting.

The purpose of the study was to measure and compare horizontal head and eye tracking movements as baseball batters "took" pitches and swung at baseball pitches. Two former college baseball players were tested in two conditions. A pitching machine was used to project tennis balls toward the subjects. In the first condition, subjects acted as if they were taking (i.e., not swinging) the pitches. In the second condition, subjects attempted to bat the pitched balls. Head movements were measured with an inertial sensor; eye movements were measured with a video eye tracker. For each condition, the relationship between the horizontal head and eye rotations was similar for the two subjects, as were the overall head-, eye-, and gaze-tracking strategies. In the "take" condition, head movements in the direction of the ball were larger than eye movements for much of the pitch trajectory. Large eye movements occurred only late in the pitch trajectory. Gaze was directed near the ball until approximately 150 milliseconds before the ball arrived at the batter, at which time gaze was directed ahead of the ball to a location near that occupied when the ball crosses the plate. In the "swing" condition, head movements in the direction of the ball were larger than eye movements throughout the pitch trajectory. Gaze was directed near the ball until approximately 50 to 60 milliseconds prior to pitch arrival at the batter. Horizontal head rotations were larger than horizontal eye rotations in both the "take" and "swing" conditions. Gaze was directed ahead of the ball late in the pitch trajectory in the "take" condition, whereas gaze was directed near the ball throughout much of the pitch trajectory in the "swing" condition.

Modeling and Control of a Powered Parafoil in Wind and Rain Environments

A novel modeling method, based on computational fluid dynamics (CFD) to simulate a parafoil flying in rain and wind environments, is proposed. Then, the dynamic model of the powered parafoil in the complex environment is established on the basis of revised aerodynamic equations. By introducing path-following controllers based on active disturbance rejection control (ADRC), horizontal and longitude trajectory tracking of the powered parafoil in realistic environments are simulated. Results verify the effectiveness of the model and control methods.

Characterization of track geometric imperfections leading to maximal dynamic amplification of internal forces in railway bridges

ABSTRACT This paper resorts to a simplified dynamic analysis methodology for the study of vibrations in railway bridges produced by the passage of a typical passenger train, or EUT (Electric Unit Train). It starts from a model with fifteen degrees-of-freedom, namely vertical (bounce) and horizontal displacements (sway) and rotations about the longitudinal (roll), transverse (pitch) and vertical (yaw) axes. In this methodology, dynamic models of the train and the bridge are assumed to be initially uncoupled, yet being bound by the interaction train-bridge forces. Thus, the loads are evaluated for the train running on a rigid and fixed deck, considering geometric irregularities, different for each rail line, in both the vertical and horizontal track planes, as well as in the wheels. The contact forces are statically condensed at the vehicle’s centre of gravity and applied on a simplified 3D beam model. To represent the train passage over the bridge, functions are used to describe the interaction forces at each node of the beam model, as time evolves. Thus, it is possible to identify the dynamic response caused by the geometric irregularities and also evaluate the dynamic amplification obtained for any internal force, which is compared to the impact coefficient proposed by the Brazilian standards for the design of railway bridges (NBR 7187), used in quasi-static analysis. For the sake of an illustration, a thirty-six-metre-span concrete bridge with box girder section was considered. A study was carried out to find out the parameters of the irregularity functions that could potentially lead to maximal amplification of internal forces in the bridge.

Electro-oculography based horizontal gaze tracking: A perspective for attention-driven hearing aids

Users of hearing aids with standard directional microphones can have difficulties in complex listening situations such as multi-talker environments because they must turn their heads to follow conversations that move rapidly from one talker to the next. The use of gaze-pointed hearing aid directionality has been suggested as a way to potentially alleviate this problem [Kidd et al. (2013); J. Acoust. Soc. Am. 2013; 133(3): EL202-7.] However, to arrive at a practical and usable device, there is the need for unobstructive and mobile technology for gaze tracking. Here, we propose and evaluate an algorithm for estimating eye-gaze angle based solely on the single channel electro-oculogram (EOG), which can be obtained directly from the ear canal using conductive hearing aid molds. In contrast to conventional techniques, we use an algorithm which calculates the absolute eye angle by statistical analysis of the saccades. This results in robust long term performance where predicted eye angles significantly correlate with actual eye angles. This opens up the possibility of an attention driven beam-former for hearing aids without the need for eye-tracking goggles. [This work was supported by the Medical Research Council [grant number U135097131], Chief Scientist Office (Scotland) and Oticon Foundation.]

Performance of off-grid residential solar photovoltaic power systems using five solar tracking modes in Kunming, China

This paper compares the performance of a 2.02 kWp off-grid residential solar photovoltaic (PV) power system using PVSYST simulation software for a household in Kunming, Yunnan province, China. The monthly available solar energy; missing energy; array, final, and reference yields, performance ratio; and array capture and system losses were analyzed for five solar tracking modes: fixed tilted plane, seasonal tilt adjustment, horizontal axis tracking, vertical axis tracking, and dual axis tracking. Although there were some similar aspects across the five systems, minimum available solar energy (2461 kWh/y) and maximum missing energy (134.68 kWh/y) were obtained using the fixed tilted plane system (tilt angle = 25°, azimuth angle = 0°), whereas maximum available solar energy (3081 kWh/y) and minimum missing energy (48.53 kWh/y) in October were obtained using the dual axis tracking system. Average monthly performance ratio was maximal for the fixed tilted plane system (0.689), and minimal for the dual axis tracking system (0.596).

X-stern 배열을 가진 대형급 무인잠수정의 경로점 추적

This paper focuses on a horizontal waypoint tracking and a speed control of large diameter unmanned underwater vehicles (LDUUVs) with X-stern configuration plane. The concerned design problem is converted into an asymptotic stabilization of the error dynamics with respect to the desired yaw angle and surge speed. It is proved that the error dynamics under the proposed control scheme based on the linear control and the feedback linearization can be considered as a cascade system; the cascade system is asymptotically stable if its nominal systems are so. This stability connection enables to separately deal with the waypoint tracking problem and the speed control one. By using the sector nonlinearity, the nominal system with nonlinearities is modeled as a polytopic linear parameter varying (LPV) system with parametric uncertainties. Then, sufficient linear matrix inequality (LMI) conditions for its asymptotic stabilizability are derived in the sense of Lyapunov stability criterion. An example is given to show the validity of the proposed methodology.

A model for the rapid assessment of the impact of aviation noise near airports.

This paper introduces a simplified model [Rapid Aviation Noise Evaluator (RANE)] for the calculation of aviation noise within the context of multi-disciplinary strategic environmental assessment where input data are both limited and constrained by compatibility requirements against other disciplines. RANE relies upon the concept of noise cylinders around defined flight-tracks with the Noise Radius determined from publicly available Noise-Power-Distance curves rather than the computationally intensive multiple point-to-point grid calculation with subsequent ISO-contour interpolation methods adopted in the FAA's Integrated Noise Model (INM) and similar models. Preliminary results indicate that for simple single runway scenarios, changes in airport noise contour areas can be estimated with minimal uncertainty compared against grid-point calculation methods such as INM. In situations where such outputs are all that is required for preliminary strategic environmental assessment, there are considerable benefits in reduced input data and computation requirements. Further development of the noise-cylinder-based model (such as the incorporation of lateral attenuation, engine-installation-effects or horizontal track dispersion via the assumption of more complex noise surfaces formed around the flight-track) will allow for more complex assessment to be carried out. RANE is intended to be incorporated into technology evaluators for the noise impact assessment of novel aircraft concepts.

RESEARCH ON MINES RESCUE BRIGADESMEN'S TRAINING IN A NEW TRAINING FACILITY DESIGNED AND BUILT FOR CONFINED SPACES

Working in confined (limited) spaces represents a risk factor generating unwanted accidents or events, having an impact on human health. The success of intervention and rescue operations in toxic or chemical aggressive environments lies in optimal and efficient design of the training process for rescue personnel, which also includes rescue operations in confined spaces. The paper presents the scientific research behind designing and building a complex training facility with different training tracks, having various levels of difficulty, achieved within a research project funded by the Romanian National Agency for Scientific Research, within the NUCLEU program. The training facility allows for simulation of intervention activities in spaces having horizontal and vertical tracks, poor visibility, high temperature and humidity environments, and so on, with the purpose of preparing intervention and rescue teams for situations similar to real life.

Two-Dimension Numerical Simulation of Parabolic Trough Solar Collector: Far North Region of Cameroon

Cameroon lives in the era of great infrastructures in order to reach the economic emergence by 2035. These infrastructures require a solid framework of energy provisions from many natural energy sources and resources that the country possesses. Speaking of natural energy resources, the country is particularly gifted by solar energy potential in the far north. This region of the land is densely populated but much of the populations do not have access to electricity since they live in remote areas far from national electricity grid. Solar thermal energy appears then as real potential to fulfill the growing demand of energy and reduce fossil fuel use dependence. Moreover, it would also be a grandiose opportunity for hospitals in these regions to provide hot water for Sterilization. As the design of a solar thermal plant strongly relies on the potential of direct solar irradiance and the performance of a solar parabolic trough collector (PTC) estimated under the local climate conditions, in this paper, we annually compute direct solar radiation based on monthly average Linke turbidity factor and various tracking modes in two chosen sites in the far north region of Cameroon. Also, a detailed two dimensional numerical heat transfer analysis of a PTC has been performed. The receiver has been divided into many control volumes along his length and each of them is a column consisting of glass, vacuum, absorber and fluid along which mass and energy balance have been applied. Direct solar irradiation, ambient temperature optical and thermal analyses of the collector receiver takes into consideration all modes of heat transfer and the nonlinear algebraic equations were solved simultaneously at each instant during a day of computation using Engineering Equation Solver (EES). To validate the numerical results, the model was compared with experimental data obtained from Sandia National Laboratory (SNL). It has shown a great concordance with a maximum relative error value of 0.35% and thermal efficiency range of systems about 66.67% - 73.2%. It has also been found that the one axis polar East-West and horizontal East-West tracking with 96% and 94% of full tracking mode respectively, were most suitable for a parabolic trough collector throughout the whole year in the two towns considered.

COLORS OF ELLIPTICALS FROM GALEX TO SPITZER

ABSTRACT Multi-color photometry is presented for a large sample of local ellipticals selected by morphology and isolation. The sample uses data from the Galaxy Evolution Explorer (GALEX), Sloan Digital Sky Survey (SDSS), Two Micron All-Sky Survey (2MASS), and Spitzer to cover the filters NUV, ugri, JHK and 3.6 μm. Various two-color diagrams, using the half-light aperture defined in the 2MASS J filter, are very coherent from color to color, meaning that galaxies defined to be red in one color are always red in other colors. Comparison to globular cluster colors demonstrates that ellipticals are not composed of a single age, single metallicity (e.g., [Fe/H]) stellar population, but require a multi-metallicity model using a chemical enrichment scenario. Such a model is sufficient to explain two-color diagrams and the color–magnitude relations for all colors using only metallicity as a variable on a solely 12 Gyr stellar population with no evidence of stars younger than 10 Gyr. The [Fe/H] values that match galaxy colors range from −0.5 to +0.4, much higher (and older) than population characteristics deduced from Lick/IDS line-strength system studies, indicating an inconsistency between galaxy colors and line indices values for reasons unknown. The NUV colors have unusual behavior, signaling the rise and fall of the UV upturn with elliptical luminosity. Models with blue horizontal branch tracks can reproduce this behavior, indicating the UV upturn is strictly a metallicity effect.

A passive shoulder joint tracking device for effective upper limb rehabilitation

This paper presents development and evaluation of a passive shoulder joint tracking device for allowing natural three-dimensional movement of the shoulder joint (Glenohumeral joint) during upper limb rehabilitation. The shoulder joint is one of the most sophisticated joint in human body as it involves not only three-dimensional rotation but also three-dimensional translation simultaneously. Existing upper limb rehabilitation devices account for three-dimensional rotation of the shoulder joint but lack in three-dimensional translation. This paper presents design and analysis of a three-degrees of freedom (DOF) passive shoulder joint tracker that allows natural translation of the joint in three-dimensional space. One-DOF vertical tracker compensates for the weight of arm and device by using simple spring mechanism and two-DOF horizontal tracker consists of two-link mechanism allowing twodimensional translation in horizontal plane. Performance of the passive tracker was evaluated through an experimental analysis with eight human subjects. An upper limb rehabilitation device (J-WREX) combined with the tracker allowed greater range of motion (ROM) of the shoulder joint in all three directions and followed the shoulder joint with acceptable tracking error. The passive tracker can be attached to existing upper limb devices to improve the performance by allowing natural shoulder joint movement.

Autonomous homing control of a powered parafoil with insufficient altitude

In order to realize safe and accurate homing of a powered parafoil under the condition of insufficient initial altitude, a multiphase homing path is designed according to the flight characteristics of the vehicle. With consideration that the traditional control methods cannot ensure the quality of path following because of the nonlinear, large inertial and longtime delay existed in the system and strong disturbances in a complex environment, a homing controller, composed of the vertical and horizontal trajectory tracking controllers, is designed based on active disturbance rejection control (ADRC). Then autonomous homing simulation experiment of the powered parafoil with insufficient altitude is carried on in a windy environment. The simulation results show that the planned multiphase homing trajectory can fulfill the requirements of fixed-point homing and flare landing; the designed homing controller can overcome the influences of uncertain items of the internal and external disturbances, track the desired homing path more rapidly and steadily, and possesses better control performances than traditional PID controllers.

Evaluation and Acceptability of a Simplified Test of Visual Function at Birth in a Limited-Resource Setting.

Neurological examination, including visual fixation and tracking of a target, is routinely performed in the Shoklo Malaria Research Unit postnatal care units on the Thailand-Myanmar border. We aimed to evaluate a simple visual newborn test developed in Italy and performed by non-specialized personnel working in neonatal care units. An intensive training of local health staff in Thailand was conducted prior to performing assessments at 24, 48 and 72 hours of life in healthy, low-risk term singletons. The 48 and 72 hours results were then compared to values obtained to those from Italy. Parents and staff administering the test reported on acceptability. One hundred and seventy nine newborns, between June 2011 and October 2012, participated in the study. The test was rapidly completed if the infant remained in an optimal behavioral stage (7 ± 2 minutes) but the test duration increased significantly (12 ± 4 minutes, p < 0.001) if its behavior changed. Infants were able to fix a target and to discriminate a colored face at 24 hours of life. Horizontal tracking of a target was achieved by 96% (152/159) of the infants at 48 hours. Circular tracking, stripe discrimination and attention to distance significantly improved between each 24-hour test period. The test was easily performed by non-specialized local staff and well accepted by the parents. Healthy term singletons in this limited-resource setting have a visual response similar to that obtained to gestational age matched newborns in Italy. It is possible to use these results as a reference set of values for the visual assessment in Karen and Burmese infants in the first 72 hours of life. The utility of the 24 hours test should be pursued.