Axis Tracking Research Articles

The moving chord method for determining the curvature of the track axis

Abstract: The paper adresses the issue of determining the curvature of the axis of the railway track in order to enable the determination of the geometrical characteristics of the measured route. A new concept of determining the curvature was used by the method of changing the angles of inclination of a moving (virtual) chord based on the knowlege of the Cartesian coordinates of a given region of the route. The verification of the proposed method, carried out on unambiguosly defined model geometric track layouts, showed the complete agreement of the obtained curvature diagrams with the diagrams constituting the basis for obtaining the corresponding geometric solution. The use of the moving chord method to determine the curvature of the operated railway track showed that the obtained curvature plots clearly differ from those for model layouts; they have a less regular, oscillating character, which results from the track deformation and measurement error. However, this does not prevent the possibility of estimating the basic geometrical parameters of the measured layout on this basis. Keywords: railroad; curvature of the track axis; verification of a new calculation method; determination of application possibilities

Implications of spatial-temporal shading in agrivoltaics under fixed tilt & tracking bifacial photovoltaic panels

The spatial and temporal behavior of the incident sunlight can have important implications for agrivoltaic (AV) crop yield. Here we explore the short term (daily) and long term (monthly) variations of the photosynthetically active radiation (PAR) under various tracking and fixed-tilt agrivoltaic PV modules configurations and propose strategies to minimize the shade-induced crop yield loss. For a fixed row to row PV module spacing, vertically installed PV modules facing East/West provide the best spatial homogeneity and a higher intensity of net daily incident PAR, while the traditional North/South faced fixed tilt PV modules result in a high spatial contrast, i.e., a significantly lower PAR underneath the PV modules as compared to the open space between the adjacent rows of PV modules. The shading behavior for the horizontal single axis tracking PV modules shows a seasonal dependence, a higher shading vertically below the PV modules during winters and vice versa for summers. The spatial variation in the crop yield correlates well with that of the net daily PAR spatial pattern in the case of the shade sensitive crops (e.g., tomato) while the spatial yield for the shade tolerant crops (e.g., lettuce) is less affected by PAR variations. We propose an intercropping approach where the cultivated areas for crops having high and low shade sensitivity are identified based on the calculated spatial PAR pattern. A case study of intercropping lettuce with tomato under various PV module configurations shows that this approach can minimize the biomass loss for shade sensitive crops in the presence of spatial PAR heterogeneity.

Location and orientation based performance analysis of 4.98 kWp solar photovoltaic system for isolated Indian islands

The electricity needs of Indian islands are supplied primarily by diesel generators, whereas solar photovoltaic (SPV) power can fulfil most of the electricity requirements. The performance analysis is the correct path to assess the potential and design aspects for the sustainable growth of future SPV installations. In this regard, several studies have been performed, but the influence of various solar trackers on the performance of the SPV system in Indian islands has not been considered thoroughly. This article investigates the feasibility and evaluates the performance indices of 4.98 kWp SPV systems in different islands (Agatti, Chetlat, Minicoy, and Port Blair) considering fixed axis tracking. Moreover, the effect of various tracking systems (one axis, two axis, azimuth axis, and seasonal tilt) on the system's performance have also been analysed in Port Blair island. The methodology includes the collection of legacy data from NSRDB, modelling of SPV system in System Advisor Model platform, and formulation of performance indices according to IEC 61724 standards. The study has found that the system's annual AC energy productions (AEP) in Agatti, Chetlat, Minicoy, and Port Blair islands are 7,560.91 kWh, 7,468.83 kWh, 7,495.21 kWh, and 6,935.06 kWh, respectively. Additionally, the AEP in Port Blair Island for one axis, two axis, azimuth axis and seasonal tilt tracking is increased by 19%, 25%, 9%, and 4%, respectively, compared to fixed axis tracking. The study has also found that the yearly mean normalized reference yield, array yield, final yield, array capture losses, system loss, performance ratio and capacity factor are in the range of (5.41–6.86) h/d, (4.03–5.04) h/d, (3.82–4.79) h/d, (1.39–1.82) h/d, (0.21–0.25) h/d, (70.07–70.88)%, and (15.92–19.94)% respectively. Finally, the analysis has proven that the SPV system with two axis tracking is technically viable for isolated Indian islands.

The “Fresnel Equations” for Diffuse radiation on Inclined photovoltaic Surfaces (FEDIS)

The well-known Fresnel equations solve for the reflection and transmission of light for precise incident angles. The transmission of diffuse radiation incident on a planar or domed surface is often needed for real-world applications. Due to the complexity of the Fresnel equations, the analytical solution of the integration has hitherto been unobtainable over the last centuries. Therefore, this problem was numerically solved by integrating the angular transmittances in space often leading to substantial computing burden and bias in the results. To efficiently estimate the solar energy resource for a glass-covered photovoltaic (PV) module, we derive an analytical solution of diffuse transmission based on the rigorous integration of an alternate form of the Fresnel equations. The approach leads to a simple yet accurate relative transmittance model that reconciles the solar energy sensed by pyranometers and PV panels. With limited and clearly stated approximations, the complex mathematical derivation resulted in an elegant solution. An experiment using 1-year of data at the National Renewable Energy Laboratory's (NREL's) Solar Radiation Research Laboratory (SRRL) shows that the new model dramatically decreases the disparity between the solar radiation measurements by a Kipp and Zonen CM Pyranometer 22 (CMP22) and an IMT reference cell on a 1-axis tracking system. The solution in this paper can be widely used in scientific and engineering research, development, and applications wherever the Fresnel equations are used.

Utilising high-fidelity 3D building model for analysing the rooftop solar photovoltaic potential in urban areas

There are multiple approaches of estimating solar power generation by rooftop solar photovoltaic (PV) systems. Methods processed using GIS as well as 3D models provide the most reliable and accurate results. However, with the restriction of a limited detail 3D model area, estimations on a regional scale are hard to achieve. The regional power potential can be predicted by identifying the correlation of rooftop areas and the shadowing effect changing between the Level of Detail (LOD)1 and LOD2 models in the case study areas. This research considers the aspects and angles of the rooftops, to try and not only figure out the optimal PV installation conditions but also to make a general estimation for optimal angle, 2-axis solar tracking as well as total solar radiation received scenarios. The results of the research indicate that the optimal annual angle is 177° and 13° in aspect and slope degree, respectively, and the improvements of power generation under those three scenarios increase from about 2 to 16% in the test area, respectively. This research also showed that the power potential in partial small areas had the same tendency as the whole region even though each part of the small area had uneven city pattern. Additionally, different from most of the study, north-facing rooftops had been proved to have the strong potential to be developed as a solar power PV panel site and should not be neglected from the whole PV system.

Crop-Specific Optimization of Bifacial PV Arrays for Agrivoltaic Food-Energy Production: The Light-Productivity-Factor Approach

Agrivoltaics (AV) is an emerging technology having symbiotic benefits for food-energy-water needs of the growing world population and an inherent resilience against climate vulnerabilities. An AV system needs to balance the sunlight sharing between the solar panels and crops to maintain the desired food-energy yields, subject to appropriate constraints. Given the emerging diversity of monofacial and bifacial farms, the lack of a standardized crop-specific metric (to evaluate the efficacy of the irradiance sharing) has made it difficult to optimize/assess the performance of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\mathrm{AV}}$</tex-math></inline-formula> systems. Here, we introduce a new metric—light productivity factor (LPF)—that evaluates the effectiveness of irradiance sharing for a given crop type and photovoltaic (PV) array design. The metric allows us to identify optimal design parameters including the spatial PV array density, panel orientation, and single axis tracking schemes specific to the photosynthetically active radiation needs of the crop. By definition, LPF equals 1 for PV-only or crop-only systems. The AV systems enhances LPF between 1 and 2 depending on the shade sensitivity of the crop, PV array configuration, and the season. While traditional fixed-tilt systems increase LPF significantly above 1, we find LPF is maximized at 2 for shade-tolerant crops with a solar farm based on single axis sun tracking scheme. Among the fixed tilt systems, east/west faced bifacial vertical solar farms is particularly promising because it produces smallest variability in the seasonal yield for shade sensitive crops, while providing LPF comparable to the standard N/S faced solar farms. Additional benefits include reduced soiling and ease of movement of large-scale combine-harvester and other farming equipment.

Acoustic impact on bridges

The paper analyzes the influence of various factors on the level of acoustic impact during the passage of trains on bridges with span structures made of various materials. In the course of the work, a qualitative analysis of the measurement conditions (type of rolling stock, bridge structure design, acoustic conditions, etc.) and factors (span type, design of the cushion layer, distance from the noise source, climatic factors) affecting the maximum or equivalent sound level was carried out. Direct measurements of the maximum and equivalent sound levels on bridges with different spans were made. When the freight train passes, the greatest acoustic impact occurs on metal spans, the maximum sound level on which is recorded at a distance of 6.5 m from the track axis up to 99 dBA. If all else being equal – the speed of the train, its length, irregularities on the surface of the rails and wheels of the rolling stock, natural, climatic and external acoustic conditions, the most significant influence on the level of acoustic impact has a constructive solution of bridge structures – the type of span structure and the material from which it is made, as well as the damping capacity of the cushion layer between the plates of the ballastless bridge deck (BBD) and the longitudinal beams of the spans. The least acoustic impact on the environment is exerted by reinforced concrete and all-composite spans, which determine the lower sound level in comparison with metal spans by 6-8 dBA. Laying an elastic cushion layer between BBD slabs and longitudinal beams reduces the acoustic impact on metal spans by up to 2-3 dBA.

Comparative study of solar tracking and fixed-tilt photovoltaic modules in Morocco

Nowadays the global energy context is being difficult, looking for other alternatives is obviously observed in many countries, and the expectations in terms of renewable energies are increase continuously. Taking the example of photovoltaic energy with its environmental advantages and especially the fixed-tilt solar panel. This technology is used to optimize radiation received, and more the surface of a solar panel is perpendicular to incident rays, more the efficiency is better, hence the objective of our work. In this context, a comparative study between a fixed-tilt panel and a panel with a 2-axis Open Loop tracking system is performed for the first time in AFRICA, and exactly in the 6 regions of MOROCCO distributed according to their solar potential. The comparative study is done on Matlab/Simulink software, in which the incident radiation for both systems is calculated from a radiation model based on zenith and azimuth angles obtained via the Solar position algorithm; the photovoltaic power is also calculated in our program. As a results, we found that the use of open-loop solar tracking systems in less sunny areas and periods increase the productivity of photovoltaic panels and consequently improves its energy efficiency.

The effect of spectral albedo in bifacial photovoltaic performance

This paper analyzes 15-months of spectral albedo measurements collected at the Technical University of Denmark (55.6°N, 12.1°E). High-resolution spectroradiometers are used to monitor four albedo scenarios, which include green vegetation, dry vegetation, gravel, and snow. Spectral mismatch and spectral impact are calculated for the front and backside of three different bifacial cell concepts mounted on horizontal single axis trackers and fixed-tilt substructures. The spectral nature of albedo is shown to have significant influence on bifacial photovoltaic performance wherein backside spectral impact as high as 1.20 is observed for fixed-tilt systems above green vegetation and as low as 0.98 for systems above snow. The results reveal that spectral impact is always lower on tracked than fixed-tilt systems because a greater fraction of sky diffuse light reaches the backside of tracked systems. Given the variety of albedos tested here, we find that the normalized difference vegetation index is a good predictor of backside spectral effects. When the high-resolution measurements are truncated to 4 to 8 carefully selected wavelengths, we find that this limited measurement resolution sufficiently captures the seasonal spectral albedo fluctuations that influence bifacial photovoltaic energy production. Finally, to alleviate the dearth of spectral datasets presently available to the PV community, the spectral irradiance and albedo measurements are made freely available in open access format (https://doi.org/10.11583/DTU.14695437.v1).

An Analytical Approach to Intertrack Space Widening on Railroad Curves

The article addresses the issue of designing the geometry of a curved double track using the analytical design method principles. This allowed, similarly to other applications of the method, a complete overview of the issue and the method for determining the key parameters to be defined. The analytical method for determining the intertrack space axis and the outer and inner track axes is introduced, leading to the required value of the intertrack space widening. The widening is achieved by varying the length of the transition curves in the outer and inner tracks. With the track axis coordinates in the local coordinate system, these can be easily transferred to the PL-2000 two-dimensional Cartesian coordinate system, i.e., an element of the national spatial reference system. The analysis continues with the issue of the chainage of axes of the intertrack space and the mainline tracks. The applicability of the proposed method and its high precision are demonstrated by examining a wide radius range of circular curves. Keywords: railway track, widening of the intertrack space, determining the curved track axis, railway line chainage

Sistem Monitoring Penentuan Pergerakan Posisi Panel Surya Terintegrasi Internet Of Things

Due to the increasing demand for energy, alternative energy is needed. One of them is energy that comes from the sun. To utilize solar energy, solar panels are needed which are used to collect solar energy which will be converted into electrical energy. The problem is to optimize the work of the solar panel, a design for determining the position of the solar panel must be made so that it is always focused on the direction of the arrival of the sun. Design of solar panel position monitoring system based on the Internet of Things has a purpose as a monitoring system in optimizing the light reception received by solar panels in real time. The method used is the dual axis tracking method, which is a method that can make flexible solar panel movements follow the direction of the maximum sunlight intensity. The parameters monitored from this research are the value of analog voltage from the four LDR light sensors, two angles of dual axis movement and description of the the solar panel position. From the tests that have been carried out, the system can work well as solar panel movement position monitoring system based on the Internet of Things.

Influences of tracking and installation errors on the optical performance of a parabolic trough collector with heat pipe evacuated tube

In this study, the parabolic trough collector with heat pipe evacuated tube is used as the research object. Using the ray tracing method, this study analyzes the effect of tracking error of azimuth-elevation axis and receiver installation error on the optical performance of the collector. A test bench for the azimuth-elevation axis manual tracking device of the parabolic trough concentrator was designed and built, and the heat flux distribution at the focal plane was measured. The optical simulation results were compared with the test results to verify their accuracy, and the maximum relative error was 2.69%. The simulation results were compared with those calculated in the literature, and the maximum error was 16.23%. Simulation results show that the circumferential heat flux of the receiver is still symmetrically distributed when longitudinal incidence angles and vertical installation errors were found. The symmetry disappeared when transverse incidence angles and horizontal installation errors were found. As the tracking error of the elevation axis increases, the optical efficiency of the collector decreases, and the length of the end loss increases. For the collector in this study, the azimuth axis tracking error is less than 1.5° and the elevation axis tracking error is less than 6°, which can ensure high optical efficiency. The vertical installation error of the receiver was |Δz| <17 mm, the horizontal installation error was |Δx| < 20 mm, and the optical efficiency of the collector remained unchanged. The calculation method and results in this study can provide theoretical support for selecting an automatic tracking system with reasonable tracking accuracy and determining the allowable installation errors for the parabolic trough collector with heat pipe evacuated tube, and can also provide detailed thermal boundary conditions for the subsequent research of heat transfer performance of the receiver, which has great theoretical value.

Geological region by multi-signal method of gravity anomaly data in central Vietnam area

This paper presents the research results of applying the combined method of probabilistic statistical approaches, energy density spectral correlation, two-dimensional filtering in dynamic sliding windows, full horizontal gradient and heterogeneous axis tracking method to process and interpret the Bughe gravitational anomaly field in central area Vietnam. The calculation results have shown the superiority of the twodimensional filter in dynamic sliding windows compared to the filters in fixed windows in GEOSOFT software, GMT software. According to the physical characteristics of the field, the study area was divided into 13 homogeneous classes, this result is consistent with the geological-tectonic data in the area. In the north and northeast, the stabilized rock layers are characterized by homogeneous layers that extend in the northwestsoutheast direction. In the south and southwest, there is complex tectonic activity characterized by high density rock layers overlain by low density rock layers in each fault band with different directions of development. This suggests that there may be deeply buried mineral deposits of magmatic origin in central area Vietnam.

The Era of Janus Kinase Inhibitors for Inflammatory Bowel Disease Treatment.

For a significant proportion of patients with inflammatory bowel disease (IBD), primary non-response and secondary loss of response to treatment remain significant issues. Anti-tumor necrosis factor therapies have been licensed for use in IBD. Other disease-related pathways have been targeted as well, including the interleukin 12/23 axis and lymphocyte tracking. However, the need for parenteral administration and the associated costs of dispensing and monitoring all biologics remain a burden on healthcare systems and patients. Janus kinase inhibitors are small-molecule drugs that can be administered orally and are relatively inexpensive, thus offering an additional option for treating IBD. They have been shown to be effective in patients with ulcerative colitis (UC), but they are less effective in those with Crohn’s disease (CD). Nonetheless, given the immune-system-based mechanism of these drugs, their safety profile remains a cause for concern. This article provides an overview of Janus kinase (JAK) inhibitors and new trends in the treatment of IBD.

Determining horizontal curvature of railway track axis in mobile satellite measurements

The article discusses the applicability of a novel method to determine horizontal curvature of the railway track axis based on results of mobile satellite measurements. The method is based on inclination angle changes of a moving chord in the Cartesian coordinate system. In the presented case, the variant referred to as the method of two virtual chords is applied which consists in manoeuvring with only one GNSS (Global Navigation Satellite System) receiver. The assumptions of the novel method are formulated, and the assessment of its application in the performed campaign of mobile satellite measurements is given. The shape of the measured railway axis is shown in the national spatial reference system PL-2000, and the speed of the measuring trolley during the measurement is calculated based on the recorded coordinates. It has been observed that over the test section, the curvature ordinates differ from the expected waveform, which can be caused by disturbances of the measuring trolley trajectory. However, this problem can easily be overcome by filtering the measured track axis ordinates to obtain the correct shape – this refers to all track segments: straight sections, circular arcs, and transition curves. The virtual chord method can also be the basis for assessing the quality of the recorded satellite signal. The performed analysis has shown high accuracy of the measuring process.

Experimental study of the impact of dust on azimuth tracking solar PV in Sharjah

&lt;span&gt;Dust is one of the significant constraints in utilizing solar photovoltaic systems under harsh weather conditions in the desert regions due to creating a shadow that blocks solar irradiance from reaching solar cells and consequently, significantly reducing their efficiency. In this research, experimental study was performed to comprehend the nature of dust particles and their impact on the electrical power output that is generated from azimuth tracking solar PV modules under Sharjah environmental conditions in winter season. According to laboratory experiments, the power losses are linearly related to the dust accumulated density on the surface of the solar panel with a slope of 1.27% per g/m2. The conducted Outdoor studies revealed that the absolute reduction in output power increased by 8.46% after 41 continuous days with one low-intensity rainy day. The linear relationship obtained from indoor experiments was applied later to estimate the dust deposited density on the outdoor setup. The results showed that a regular cleaning process every two weeks is recommended to maintain the performance and to avoid the soiling loss. This work will help engineers in the solar PV plants to forecast the dust impact and figure out the regularity of the cleaning process in case of single axis tracking systems.&lt;/span&gt;

Design and Development of a Single-Axis Solar Tracking System

With solar tracking, it will become possible to generate more energy since the solar panel can maintain a perpendicular profile to the rays of the sun. Even though the initial cost of setting up the tracking system is considerably high, there are cheaper options that have been proposed over time. This research discuss the design and construction of a prototype for a solar tracking system that has a single axis of freedom. Light Dependent Resistors (LDRs) are used for sunlight detection. The control circuit is based on an ATMega328P microcontroller. It was programmed to detect sunlight via the LDRs before actuating the servo to position the solar panel. The solar panel is positioned where it is able to receive maximum light. As compared to other motors, the servo motors are able to maintain their torque at high speed. They are also more efficient with efficiencies in the range of 80-90%. Servos can supply roughly twice their rated torque for short periods. Through tracking, there will be increased exposure of the panel to the sun, making it have increased power output. The trackers can either be dual or single axis trackers. As a single tracking system is cheaper, less complex, and still achieves the required efficiency, so it was used.

Stochastic Technical Stability Test of a Passenger Railroad Car Crossing a Turnout

This article presents a definition of stochastic technical stability that was applied to test a mathematical model of a passenger railroad car crossing a turnout with the speed exceeding 160 km/h. Stability defined in this way allows testing of Lyapunov’s stability with disturbances from the track and for a nonlinear system. The STS test of a nonlinear mathematical model of a passenger car was carried out by perturbing the motion of the mathematical model with irregularities originating from the track gauge change and wheelset motion in the direction transverse to the track axis. The main aim of this paper was to determine the influence of various factors and technical conditions on the assessment of the stability of various means of transport. The analysis presented can be used to assess the dynamics of electric vehicles, whose mechanical parameters differ from those of combustion vehicles at present. The area of stable motion in the Lyapunov sense was defined using the STS method. Simulations were performed to determine the trajectory of the wheelset transverse motion. The probability of finding the wheelset in the stable motion area in relation to the rail for a single-point contact was determined. In practice, this is a one-point contact of the wheel with the rail. Conclusions from the conducted research are presented.

A review study on mathematical modeling of solar parabolic d ish‐Stirling system used for electricity generation

The intensity of the solar radiations falling on the earth surface ranges between 5 and 7.5 kWh/m2/day. For the non-directed solar thermal application, higher intensity level is required. The Concentrating Solar Power (CSP) technology incorporating reflecting mirrors reinforces the solar radiations with high intensity. It is suitable for various applications; that is, space heating, space cooling, and cooking, steam, and power generation without any polluted emissions. Meanwhile, among the various CSP technologies, the Concentrating Solar Parabolic Dish Stirling engine System (CSP-DSS) has got attention of the research community due to its various attractive features. The output power and efficiency of the CSP-DSS depend upon their geometrical, optical, and operating parameters. It is therefore, necessary to mathematically investigate the influence of these parameters on system performance before its design and installation. In the existing literature reported, only some specific parameters of the CSP-DSS have been focused and considered to investigate the system performance. To the best of author's knowledge, no literature has been found to provide the mathematical modeling of all the system parameters in a single manuscript to study and investigate their influence on the system performance. Hence, this review article aims to compile, expansively review and organize the systematical mathematical modeling for all optical, geometrical, and operating parameters of the CSP-DSS along with the system design methodology. Likewise, the effects of these parameters on the system output power and efficiency under various operating conditions have been investigated. In addition, comprehensive study of CSP-DSS components along with their classification have been painstakingly discussed to determine optimal system configuration. Finally, the latest review study in the field of CSP-DSS have been deeply and comprehensively discussed. This review study concludes that, the kinematic gamma type Stirling engine coupled with Permanent Magnet DC generator (PMDC) and Azimuth-Altitude Dual Axis Tracker (AADAT) could be the better CSP-DSS design and configuration in context of the standalone off-grid electricity generation system.

Identification of the Major Noise Energy Sources in Rail Vehicles Moving at a Speed of 200 km/h

In this work, the problematic identification of the main sources of noise occurring from the exploitation of railway vehicles moving at a speed of 200 km/h were analyzed. Within the conducted experimental research, the testing fields were appointed, measurement apparatus selected, and a methodology for conducting measurements was defined, including the assessment of noise on a curve and straight track for electric multiple units of the so-called Pendolino, an Alstom type ETR610 series ED25 train. The measurements were made using a microphone camera Bionic S-112 at a distance of 22 m from the track axis. As a result of the conducted experimental research, it was indicated that the noise resulting from vibrations arising at the wheel-rail contact (rolling noise) was the dominant source of sound.