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Modern sowing machine-tractor units (MTU) can be divided into single-machine (single-module), two-machine (double-module), and three-machine (triple-module). The firsts, consisting of a tractor and a trailed/mounted seeder, are the most studied and, therefore, the most widespread. Two-module MTUs mainly use trailed or semi-mounted hitch and trailed seeders. The units of this type have been studied less. Three-module sowing complexes are even less common. Most are based on a trailed hitch and trailed seeders placed behind the tractor. There are samples of MTU with side-mounted seeding machines, but their knowledge is extremely insufficient. This paper examines a three-module MTU based on a tractor with reverse motion and a front semi-mounted hitch. One of the problems in using this sowing unit is the choice of design parameters that would ensure safe turning when manoeuvring on the headland. Theoretical and experimental studies have established that by increasing the side seeder's towbar length, MTU's safe turning under analysis with machines of a larger operating width can be performed with a smaller distance between their inner wheels and tractor's wheels (parameter d). If the coincidence condition of side seeders' wheel axes with the tractor wheels axe is met, an increase in the tractor track from 1.7 to 2.5 m allows for a decrease in the value of the distance d. This solution is especially effective when using seeders with an operating width of 3.6 m. In this case, the indicated decrease reaches a fivefold size, from 0.5 to 0.10 m. With the seeders' operating width of 5.4 m, the distance d can only be reduced by 1.4 times. But with this option for sowing MTU, it is possible to use a tractor with dual rear tyres and a parameter d value of 0.98 m. Actual oscillations in the distance d value within 0.28 ±0.01 m in the process of turning the studied sowing machine-tractor unit at a velocity of 2.2 m·s−1 are characterized by low variance (0.64·10−4 m2) and low (no more than 1.75 Hz) frequency. This allows us to consider this MTU's mode movement on the headland quite safe. [ABSTRACT FROM AUTHOR]

Context: Urbanisation is pervasive across landscapes and seascapes and leads to the loss, degradation and fragmentation of many natural ecosystems and this has widespread consequences for animals and the ecological functions they support. While the impacts of urbanisation are understood for many individual coastal ecosystems in isolation, it is unclear how these impacts influence animal assemblages and ecological functions across different coastal ecosystems within the same landscape. Objectives: We aimed to determine how urbanisation modifies fish and crustacean assemblages and the function of carrion consumption across multiple coastal ecosystems set within the same landscape in eastern Australia. Methods: We sampled fish and crustacean assemblages in three distinct coastal ecosystems (estuaries, rocky headlands and surf zones) with baited remote underwater video systems and quantified rates of carrion consumption using scavenging assays. Results: Urbanisation had negative effects on the richness and abundance of coastal fish and crustaceans and the ecological function of carrion consumption, and these impacts were almost always consistent across estuaries, rocky headlands and surf zones. Species richness and abundance were lowest at the most urbanised sites, whereas rates of carrion consumption were lowest at sites closest to urbanised areas, across all ecosystems. Conclusions: We highlight the negative effects of urbanisation on coastal fish and crustacean assemblages, and a vital ecological function, and the consistency of these effects on distinct coastal ecosystems located within the same landscape. Managing the pervasive impacts of urbanisation on animal assemblages and ecological functions will, therefore, require targeted approaches that address the underlying impacts of urbanisation across multiple coastal ecosystems. [ABSTRACT FROM AUTHOR]

Coastal seascapes that are comprised of highly connected and complex habitats typically support a greater diversity and abundance of fish. Nearshore reef systems that are close to the coastline and therefore nearby human disturbances are, however, under significant and increasing threat from further disturbance such as commercial and recreational fisheries. In this study, inshore rocky reef fish communities were surveyed at 65 sites in eastern Australia, using baited remote underwater video stations (BRUVS) and unbaited remote underwater video systems (RUVS) with the aim of determining the spatial and habitat influences of fish communities on inshore rocky reefs and to identify whether the spatial patterns driving fish communities were consistent between BRUVS and RUVS. BRUVS were found to identify a greater abundance and diversity of fish and a greater abundance of fish from different functional groups (e.g. herbivores, omnivores, zoobenthivores and piscivores) than RUVS. Additionally, BRUVS and RUVS identified different spatial features that modified the structure of the assemblage; however, it was found that BRUVS and RUVS consistently identified seascape effects including positive impacts of reef extent and complexity and connectivity to other habitats and negative impacts associated with proximity or the extent of urbanisation nearby. The results show that the relative importance of the seascape is a constant between sampling methods, but the methods used here do not identify those patterns consistently. We did however see that fish communities were consistently more abundant and diverse on reefs that were larger in extent and more complex, while being mediated by urbanisation. [ABSTRACT FROM AUTHOR]

Headland boundary identification and ranging are the key supporting technologies for the automatic driving of intelligent agricultural machinery, and they are also the basis for controlling operational behaviors such as autonomous turning and machine lifting. The complex, unstructured environments of farmland headlands render traditional image feature extraction methods less accurate and adaptable. This study utilizes deep learning and binocular vision technologies to develop a headland boundary identification and ranging system built upon the existing automatic guided tractor test platform. A headland image annotation dataset was constructed, and the MobileNetV3 network, notable for its compact model structure, was employed to achieve binary classification recognition of farmland and headland images. An improved MV3-DeeplabV3+ image segmentation network model, leveraging an attention mechanism, was constructed, achieving a high mean intersection over union (MIoU) value of 92.08% and enabling fast and accurate detection of headland boundaries. Following the detection of headland boundaries, binocular stereo vision technology was employed to measure the boundary distances. Field experiment results indicate that the system's average relative errors of distance in ranging at distances of 25 m, 20 m, and 15 m are 6.72%, 4.80%, and 4.35%, respectively. This system is capable of meeting the real-time detection requirements for headland boundaries. [ABSTRACT FROM AUTHOR]

Increasing the productivity of machine tractor units when cultivating the field is achieved by reducing the work time, which usually relates to seeking the shortest path of the unit in the field. Reducing the length of headland turns, which account for the largest proportion of the unit non-working moves, will result in higher productivity as well as less soil compaction in the headland. The article presents an algorithm for selection of a turn in the headland of a field of irregular shape. Existing theoretical correlations have been used to determine the length of the non-working move and the headland width when making T-turns. The selection of a turn is made on the basis of the minimum length of the non-working move, after which the width of the needed headland for the selected turn is calculated. This algorithm can be added to the on-board computer of the unit thus providing a more efficient way of moving, automatically generating a headland and following the trajectory of the selected turn by the unit. [ABSTRACT FROM AUTHOR]

Headland and field edges have a higher traffic frequency compared to the field centre, which causes more compaction. Most repeated compaction is located at the field entrance area and headland during machinery turning and material transporting that takes place during the fertilisation, herbicide laying, and harvesting of fields, which could cause soil structure destruction and yield reduction. In this study, the differences between headland, field edges, and field centre were studied using yield maps and the vegetation indices (VIs) calculated by the Google Earth Engine (GEE). First, thirteen yield maps from 2019 to 2022 were used to measure the yield difference between headland, field edges, and field centre. Then, one hundred and eleven fields from northern Italy were used to compare the vegetation indices (VIs) differences between headland, field edges, and field centre area. Then, field size, sand, and clay content were calculated and estimated from GEE. The yield map showed that headland and field edges were 12.20% and 2.49% lower than the field centre. The results of the comparison of the VIs showed that headlands and field edges had lower values compared to the field centre, with reductions of 4.27% and 2.70% in the normalised difference vegetation index (NDVI), 4.17% and 2.67% in the green normalized difference vegetation index (GNDVI), and 5.87% and 3.59% in the normalised difference red edge (NDRE). Additionally, the results indicated that the yield losses in the headland and field edges increased as the clay content increased and sand content decreased. These findings suggest that soil compaction and structural damage caused by the higher traffic frequency in the headland and field edges negatively affect crop yield. [ABSTRACT FROM AUTHOR]

Headland boundary identification and ranging are the key supporting technologies for the automatic driving of intelligent agricultural machinery, and they are also the basis for controlling operational behaviors such as autonomous turning and machine lifting. The complex, unstructured environments of farmland headlands render traditional image feature extraction methods less accurate and adaptable. This study utilizes deep learning and binocular vision technologies to develop a headland boundary identification and ranging system built upon the existing automatic guided tractor test platform. A headland image annotation dataset was constructed, and the MobileNetV3 network, notable for its compact model structure, was employed to achieve binary classification recognition of farmland and headland images. An improved MV3-DeeplabV3+ image segmentation network model, leveraging an attention mechanism, was constructed, achieving a high mean intersection over union (MIoU) value of 92.08% and enabling fast and accurate detection of headland boundaries. Following the detection of headland boundaries, binocular stereo vision technology was employed to measure the boundary distances. Field experiment results indicate that the system’s average relative errors of distance in ranging at distances of 25 m, 20 m, and 15 m are 6.72%, 4.80%, and 4.35%, respectively. This system is capable of meeting the real-time detection requirements for headland boundaries.

We tested to what extent ridge-and-furrow relics can be identified with airborne LiDAR imagery and analysed whether the ridge-and-furrow can provide an archive of historical parcellation dynamics in open strip-fields. Our case study area is the central-eastern Netherlands (Twente; Veluwe) and adjacent lowland Germany (Westphalia). We sampled eight mark territories containing twenty-one neighbourhoods with unurbanised open strip-fields. The sample contained coversand, ground moraine and ice-pushed ridge landscapes. The study was based on LiDAR-derived elevation models (DEM), historical cadastres and topographic maps, soil and geomorphological maps as well as an archaeological excavation. Ridge-and-furrow relics of 1–2 decimetres height, invisible to the naked eye, were detected in every strip-field. In large strip-fields, raised headland relics divided ridged beds into two shorter strip parcels. In afforested parts of strip-fields, ridge-and-furrow was generally better preserved. Ridged beds were broadly congruent with cadastral strip parcels from the early nineteenth century. However, cadastral strip parcels were often shorter than ridge-and-furrow beds but frequently several beds wide. The identified micro-topographic patterns turned out to be an archive of historical reparcellation dynamics. [ABSTRACT FROM AUTHOR]

Material transport around the headland has received more attention. To reveal the material transport pattern and its response to the topography in the Yellow River Estuary (YRE), in this paper, three Lagrangian analysis methods, including Lagrangian residual current, particle tracking model, and Lagrangian coherent structures (LCSs), are used to analyze the material horizontal transport near the headland in the YRE. The results of the study show that the headland plays an important role in the hydrodynamic processes and material transport in the YRE. Due to the current shear induced by the topography, materials easily diffuse, forming a front around the headland. Due to the blocking and shading effects of the headland, the materials tend to accumulate on the right side of the headland (facing the sea). The above three Lagrangian methods can describe the characteristics of the material distribution, but the LCS method is superior in comparison. Due to their more stable spatial structure, LCSs can be used to analyze the transport of pollutants, larvae, microplastics, etc. in the YRE.

Taborda, R. and Silva, A.N., 2024. Modeling shoreline evolution on platform beaches. In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 283-288. Charlotte (North Carolina), ISSN 0749-0208. Embayed and shore platform beaches, common along rocky coastlines, are highly vulnerable to changes in oceanographic conditions and sediment supply. Coastal changes in embayed beaches involve sediment redistribution within embayments and exchanges between neighboring embayments, particularly in open or leaky sediment cells. Despite their importance, there is a shortage of shoreline models that couple shoreline evolution with sediment bypassing. The study introduces SEM-PLAT, a shoreline evolution model applicable to both low-lying sandy coasts and shore platform beaches on rocky coasts. Unlike traditional models, SEM-PLAT considers the dynamic behavior of the beach toe over time and sediment exchanges between embayments. It incorporates spatial gradients in wave-induced longshore sediment transport and a dynamic profile model, providing a comprehensive framework for complex shoreline evolution. Applications of SEM-PLAT demonstrate its effectiveness in simulating coastal processes, including beach development, rotation, and sediment bypassing. This model highlights key coastal geomorphological processes and offers a versatile tool for shoreline evolution studies and coastal management strategies. [ABSTRACT FROM AUTHOR]

Analytical relations for determining the headland width when making T-turns by a machine-tractor unit with a mounted machine on an irregularly-shaped field have been specified. Five types of T-turns are described in two variants - open turn and closed turn. Each of these is done in two directions of movement. A total of 20 variants of the turns are described. The method for determining the headland width of a specific machinetractor unit consisting of a tractor and mounted row seeder is demonstrated. For each type of turn the headland width is determined according to the angle between the direction of movement of the agricultural unit and the field border. A range of angle modification from 10° to 90° is adopted. The analysis shows that for obtaining minimum headland width closed turns in the left to right direction of movement should not be made. The smallest theoretical headland width is when making a closed T-turn with arch-shaped backward movement and left-to-right direction of movement on the field. When using T-turns with an arch-shaped backward movement and T-turns with straight-ahead movement when entering the headland, the actual headland width is the same (6 m) regardless of the type and direction of the turn. [ABSTRACT FROM AUTHOR]

The reduction in cereal crop yields on field headlands has previously been examined in other geographical regions, with research focusing on the relationship between yield and the distance from the crop edge. Headlands are subject to greater machinery trafficking than the centre of the field and the level of traffic imposed depends on the machine size and adopted turning practice. The aim of this work was to examine the impact of turning headlands on crop performance in a survey of 40 field sites in Irish conditions. The headland was categorised into three distinct zones: the area next to the field edge subject to moderate traffic intensities (field edge); the main headland area of greatest turning traffic (turning) and a transition zone (transition). An in-field zone (in-field) in which no machinery turns occur was also included. The 2-year survey included sites from three regions, four soil texture classes and had crops established with plough-based systems. Crop measurements, including plant densities, shoot counts and light interception, and yields were recorded at each site and included winter barley (WB), spring barley (SB) and winter wheat (WW) crops. The yield response of each crop type varied with sample zone, region and soil texture. There were significant (P < 0.001) yield differences recorded between the turning area and in-field zone for all three crops. Winter barley yields were reduced by 1.3 t/ha in the turning zone compared with the in-field section, while SB and WW had yield reductions of 2.08 and 4.04 t/ha, respectively, between these two field zones.

تعد رأس الأدبية هي الرأس الأرضية الوحيدة الموجودة بالساحل الشمالي الغربي لخليج السويس، وهي رأس صخرية النشأة رسوبية المظهر، وقد ساهم في تکوينها العديد من العوامل لعل أهمها تغير مستوى سطح البحر، ويبلغ أقصى طول لها على امتداد محور شمالي شرقي ـــــ جنوبي غربي 4.3کم، وأقصى عرض على امتداد محور شمالي شمالي غربي ـــــ جنوبي جنوبي شرقي 3,4کم، وتبلغ مساحتها 7.54کم2.ويتناول البحث دراسة الملامح الجغرافية الطبيعية لرأس الأدبية، وعوامل وعمليات التشکيل المؤثرة على نشأتها وتطورها، والخصائص الطبيعية لرواسبها السطحية، وأشکال السطح المرتبطة بها، وأهميتها التطبيقية. Ras al-Adabiya is the only Headland on the northwest coast of the Suez Gulf, and it is the head of rocky sedimentary emergence, and many factors contributed to its formation, perhaps the most important of which is the change of sea level, and its maximum length is 4.3 km, the maximum width is 3.4 km, and it is area is 7.54 km2. The research deals with the study of the natural geographical features of Ras al-Adabiya, the formation factors and processes affecting its origin and development, the natural characteristics of its surface deposits, the Land Forms associated with it, and it is importance Applied.

There is increased stress on soil and crop quality caused by machinery traffic during field operations in tillage systems, especially the area where the machinery turns, known as the headlands. While the influence of traffic on soil physical quality is understood, the impact on soil chemical quality and soil fertility is less so. Furthermore, correcting soil fertility and chemical quality in fields under cereal tillage requires strategic sampling due spatial variability, specifically in headlands. Using a simplified sampling strategy, the objective of this study was to examine the variability in soil chemical quality within traffic-dependent zones in the headland. In a case-study in Ireland, 41 fields under tillage were surveyed, and soil sampling zones delineated within headlands based on typical field traffic patterns. Soil phosphorus (P), potassium (K), lime requirement (LR), pH and organic matter (%OM) were measured at two depths. Elevated values of major nutrients (P, K) were recorded around the main headland tramline. Using a generalized linear mixed model, significant differences in P, K, LR and pH were found between headland zones, whereas %OM values did not vary significantly. In addition to laboratory analyses, predictions from mid-infrared spectroscopy (MIR) models resulted in similar patterns in %OM and LR with comparable statistical significance, which highlights the potential of MIR as an alternative to lab analysis of soil in traffic-dependent headland zones. Sampling headland zones to determine soil chemical quality coupled with the application of MIR for rapid soil analysis will improve decision support for soil management in tillage systems. [ABSTRACT FROM AUTHOR]

Fixed acoustic Doppler current profiler (ADCP) velocity measurements are used to investigate headland vorticity generation and recirculation in ∼20 m depth around the small (∼1 km) central California headland Pt. Sal. To reduce vorticity estimation noise, velocities are reconstructed from the first two Empirical Orthogonal Function modes representing ≈73% of the variance. Using fixed ADCPs, depth‐averaged vorticity is estimated west and south of Pt. Sal. Only one west‐location vorticity component is estimated, leading to negative vorticity bias for northward flow. The south location vorticity is consistent with estimates from parallel vessel transects on one day. The observed depth‐averaged flow V was primarily along‐bathymetric contours and varied ±0.2 ms−1 across subtidal and tidal frequency bands. The depth‐averaged normalized vorticity ζ¯/f varied ±8 across all frequency bands. Vorticity distributions are skewed with opposite sign at west and south locations, and ζ¯/f<−1 is more likely at the west location. At both locations, depth‐averaged vorticity and velocity are inversely related, with relationship asymmetric with sign of V, indicating headland and farther upstream vorticity generation. Binned‐mean ζ¯/f depends on both V and its time‐derivative, and indicates vorticity recirculation across the headland. The ∼2 h vorticity adjustment timescale and the associated short excursion distances indicate vorticity generation between south and west locations. Potential vorticity changes across the headland are different for positive and negative V indicating headland asymmetric vorticity generation. Pt. Sal occupies a nondimensional parameter space that is unique relative to other well studied headlands. Plain Language Summary: Coastal ocean flows past topographic features, such as headlands and islands, lead to a variety of processes which can enhance how much mixing and stirring occurs and have implications on the movement of marine biota and sediment. One measure of this mixing and stirring is 'vorticity,' which is a gauge of how fast the water spins. Observations from September and October 2017 are used to investigate how vorticity is created and moved around the small (∼1 km) central California headland Pt. Sal. Raw data are filtered using statistical methods to remove noise. Vorticity is estimated west and south of Pt. Sal from groups of fixed instruments measuring flow speed and direction. Separate vorticity observations from a pair of research vessels corroborate the fixed observations on a single day. Currents at the headland were a mix of oscillatory tidal (twice a day) and longer time‐scale flows. The generation of vorticity is found to be stronger for northward flow relative to southward flow. The vorticity can also recirculate back with the oscillatory tidal flow. Pt. Sal is a unique study site, especially relative to other well studied headlands which are either larger in size or in deeper water. Key Points: At a 1 km scale headland (Pt. Sal CA), depth averaged vorticity varied {plus minus}8f and was asymmetrically related to along‐headland flowVorticity also depends on flow acceleration, indicating short (2 h) adjustment timescale, recirculation, and headland generationEstimated potential vorticity across the headland indicates asymmetric vorticity generation stronger for northward flow [ABSTRACT FROM AUTHOR]

Soil quality and fertility depend on the biological and physical processes that take place in it. Intensive tillage has a negative impact not only on the soil but also on the environment. Intensive tillage has a negative impact not only on the soil but also on the environment. It is very important for farmers to evaluate the benefits of the latest technologies, such as automatic steering systems, remote monitoring systems, automation of machine functional parameters, and the installation of mechatronic sensors. The use of automatic steering systems makes it possible to avoid overlaps or uncultivated soil areas during agricultural work. Innovative technologies reduce time and fuel costs and operational costs. Properly selected field travel scheme reduces soil compaction. Due to soil compaction, crop yields are generally 10% lower than in the rest of the field. The aim of the research -- by use of telemetry platform to predict and by theoretical calculations prove the most efficient turning at headland schemes that reduces time and number of pass. For the study, the combination of Claas Xerion 5000 and 4.75 m width of Vaderstad TopDown 600 cultivator selected. The test carried out at 2.5 m s-1 tractor driving speed on a headland. Tractor were equipped with automatic steering system with RTK correction signal accuracy of ±2 cm. The tillage performed on a 45.78 ha field area. After tractor and implement turning radius and working width evaluation, the headland of 17 m width were chosen. During the study the turning time, number of passes and area covered at headland were analysed. The research data taken via remote monitoring system called telemetry. Analysis of the telemetry data shown that the tractor operator at the same shape of the headland edge selects different headland schemes. The analysis of the most rational turning schemes in the headland performed using the aggregate unit calculation turning schemes and turning lengths methodology. For the theoretical calculation, the loopless 1800 -turn angle scheme were chosen. The data analysis shown that in the case of the theoretically calculated turning scheme, the headland area would be 2.30 ha, which would make up 5.02% of the total field area. Meanwhile, the area for the headland chosen by the operator was 3.07 ha, which is 33.4% larger than the area based on theoretical calculations. According to the headland turning scheme chosen by the operator, the soil area compacted by the tractor's chassis wheels accounted for 48% of the total headland area. Meanwhile, the area for the headland according theoretical calculation of the turning scheme, was 32% of the total area for the headland, or 33% of the soil compaction area would be smaller than the headland turning scheme chosen by the operator. Also noted that the average headland path, according the driving scheme chosen by the operator, was 54.03 m. Meanwhile, the length of the headland path based on theoretical calculation decreased in 18.13 m or 33.6% less path distance than selected by operator. The reduced length of the trip for turning also resulted in a shorter driving time at the headland. Thus, the turning time in headland also reduced by 7.25% compared to the operator's chosen driving scheme. The most rational headland rotation patterns, taking into account the field shape, implement working width and turning radius, can be modelled using Telemetry platforms. [ABSTRACT FROM AUTHOR]

Delivery mechanisms for crab postlarvae along upwelling coasts have been inferred from weekly sampling, but more frequent sampling is needed to better relate highly variable oceanographic conditions to postlarval supply. Settlement of 8 crab taxa was measured in Bodega Bay, California every 2 d from 12 May through 3 July, 2002. Abundance of postlarval and juvenile settlers was cross-correlated with physical variables. Four upwelling and 4 relaxation events were recorded as fluctuations in wind stress and sea temperature during this period. Transitions to and from upwelling conditions in Bodega Bay were brief and temperature changes occurred rapidly. The strongest correlations between crab abundance and physical variables indicative of upwelling and relaxation conditions were observed for Cancer magister, which settled primarily during relaxation-favorable conditions, and for Cancer antennarius/productus, which settled primarily during upwelling-favorable conditions, suggesting interspecific differences in delivery of postlarvae to adult habitat. Weak correlations with upwelling-favorable conditions were observed for Pugettia producta/richii and Pagurus spp. Settlement of Hemigrapsus nudus, Petrolisthes cinctipes, and P. eriomerus exhibited significant correlations with changes in tidal height. These results highlight the existence of multiple taxon-specific delivery mechanisms of closely related taxa in one small geographic region. © Inter-Research 2006.

Skid-steered platforms are in use for many different purposes, including demining, military, construction and agriculture. Their power consumption varies considerably with the maneuver they are performing, depending heavily on its radius of curvature. Therefore, efficient operation of skid-steered platforms for any purpose requires proper path planning based on a mathematical model of their power consumption. With this fact in mind, this paper studies the power consumption characterization of skid-steered vehicles and presents a method based on physical principles to estimate friction on arbitrary surfaces, and then derives a mathematical model of friction in skid-steered platforms, showing that friction in such platforms depends on the radius of curvature and slip angles of the wheels. Afterwards, the derived model is used to show the optimum type of Π turns using a skid-steered platform in a coverage path planning scenario. The proposed friction model, as well as its forecast on the optimum Π turn, are verified using both indoor and outdoor field data. [ABSTRACT FROM AUTHOR]

A row-following system based on machine vision for a picking robot was designed in our previous study. However, the visual perception could not provide reliable information during headland turning according to the test results. A complete navigation system for a picking robot working in an orchard needs to support accurate row following and headland turning. To fill this gap, a headland turning method for an autonomous picking robot was developed in this paper. Three steps were executed during headland turning. First, row end was detected based on machine vision. Second, the deviation was further reduced before turning using the designed fast posture adjustment algorithm based on satellite information. Third, a curve path tracking controller was developed for turning control. During the MATLAB simulation and experimental test, different controllers were developed and compared with the designed method. The results show that the designed turning method enabled the robot to converge to the path more quickly and remain on the path with lower radial errors, which eventually led to reductions in time, space, and deviation during headland turning.

Headland rips, sometimes referred to as boundary rips, are rip currents flowing against natural or artificial obstructions extending seaward from the beach, such as headland or groynes. They can be driven either by the deflection of the longshore current against the obstacle or by alongshore variation in breaking wave height due to wave shadowing in the lee of the obstacle. The driving mechanism therefore essentially depends on the angle of wave incidence with respect to the natural or artificial obstruction. We analyze 42 days of velocity profile measurements against a natural headland at the high-energy meso-macrotidal beach of Anglet, southwest France. Measurements were collected in 6.5–10.5-m depth as tide elevation varied, during the autumn–winter period with offshore significant wave height and period ranging 0.9–6 m and 8–16 s, respectively, and the angle of wave incidence ranging from −20 ∘ to 20 ∘ . Here we analyze deflection rip configurations, corresponding to approximately 24 days of measurements, for which the current meter was alternatively located in the rip neck, rip head or away from the rip as wave and tide conditions changed. Deflection rips were associated with large offshore-directed velocities (up to 0.6 m/s depth-averaged velocities) and tide modulation for low- to moderate-energy waves. The vertical profile of deflection rips was found to vary from depth-uniform in the rip neck to strongly depth-varying further offshore in the rip head with maximum velocities near the surface. Very low frequency motions of the rip were dramatic, ranging 10–60 min with a dominant peak period of approximately 40 min, i.e., with longer periods than commonly reported. The strong offshore-directed velocities measured well beyond the surf zone edge provide new insight into deflection rips as a dominant mechanism for water and sediment exchanges between embayed (or structurally-controlled) beaches and the inner-shelf and/or the adjacent embayments.

Performance of nonworking moves by farming units in headland is associated with some expenditure of time, which reduces their productivity, as well as soil compaction leading to yield reduction. Both the reduction of length and duration of nonworking moves and reduction of the headland width are subject of numerous studies. Many manufacturers achieve this through various systems to reduce the radius of the turn of tractors and increase the speed of the front axle in turns. Recently a turning device has appeared in practice representing a fifth wheel located on the front mounting system of the tractor by means of which the turning is performed. This type of turning is applicable to mounted machines only. The present study describes various options of making turns with the tractor's fifth wheel and these are compared to the front wheel turns. The length of nonworking moves, the duration of their performance and the headland width have been determined. The results show the working widths of mounted machines where the use of a fifth wheel is effective. [ABSTRACT FROM AUTHOR]

An, S. and Takewaka, S., 2016. A study on the morphological characteristics around artificial headlands in Kashima Coast, Japan. Field observations with X-band marine radars of spatiotemporal variations of morphology around three artificial headlands were done along a well-developed 16-km-long sandy beach in 2010. The radar images were time averaged and stacked to identify water- and breaker lines around the headlands. Various characteristics of the shoreline variations were analyzed by the empirical orthogonal function method. Seasonal characteristics were discussed with seasonal incident waves and were attributed to seasonal wave conditions. Spatial variations were categorized into an asynchronous or synchronous pattern and were associated with a surf zone extension. Locations of breaker lines relative to the tips of the headlands were categorized into four types and related to the shoreline variabilities, revealing that the surf zone extension was the dominant influence on the synchronization of the shoreline variability. Shoreline positions relative to the tips of the headlands were inferred as the main cause of the surf zone extension, and frequencies of surf zone extension were understood in terms of intertidal foreshore slopes around the headlands. [ABSTRACT FROM AUTHOR]

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