Search

Detailed productivity studies were conducted on three distinct crews, all operating the modern version of the EMS Harvestline excavator-based yarder working with a motorized grapple carriage for harvesting radiata pine from plantation forests in New Zealand. Data were collected from over 1000 cycles and used to estimate robust productivity benchmarks and models. Mean productivity neared 100 t per productive machine hour (PMH) on short distances (100 m) and decreased to <70 t PMH−1 on longer ones (>200 m). In addition to very fast cycle times, only 1.5 min on average at 100 m, large stem size contributed to those very high productivity figures. Utilization ranged from 50% to 63%, with line-shifts and yarder relocation being a common delay type given the short corridors and quick extraction cycles. Productivity was 40–60 t per scheduled machine hour. This productivity range is comparable with those obtained by heavier and more expensive purpose-built swing yarders, showing great potential for cost-effective future applications. [ABSTRACT FROM AUTHOR]

Active mobility projects can potentially initiate paradigm shifts in population and urban planning decision-makers. This paper aims to conduct a social cost-benefit analysis of an active mobility project in a Colombian city. The increase of physical activity, reduction of CO2 emissions, and traffic crashes were measured in an area with suitable slopes to promote bicycles for commuting. A social cost-benefit ratio of 1.14 was found, with physical activity and road safety as the most important outcomes of the active mobility infrastructure. Furthermore, a big room for the increase and promotion of cycling as a mode of transport is addressed.

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Logging on steep terrain in our country is dangerous and low productivity. It is carried out by manual felling of the trees with a chainsaw and transportation by ropeways to a tractor or truck road. In recent years, due to the lack of manpower, the extraction and removal of wooden materials with the harvester/forwarder system, which are equipped with a traction (supporting) winch with a rope anchored to a stump or tree, has become more and more widespread. In our country, on the territory of the GS Rila Monastery, logging has been carried out using this new technology for three years. The article discusses the possible technologies and slopes at which logging can be carried out, as well as the productivity and depth of the plains of the machine chains. [ABSTRACT FROM AUTHOR]

The basic terrain-following (BTF) coordinate simplifies the lower boundary conditions of a numerical model but leads to numerical error and instability on steep terrain. Hybrid terrain-following (HTF) coordinates with smooth slopes of vertical layers (slopeVL) generally overcome this difficulty. Therefore, the HTF coordinate becomes very desirable for atmospheric and oceanic numerical models. However, improper vertical layering in HTF coordinates may also increase the incidence of error. Except for the slopeVL of an HTF coordinate, this study further optimizes the HTF coordinate focusing on the thickness of vertical layers (thickVL). Four HTF coordinates (HTF1–HTF4) with similar slopeVL but different vertical transition methods of thickVL are designed, and the relationship between thickVL and numerical errors in each coordinate is compared in the classic idealized thermal convection [two-dimensional (2D) rising bubble] experiment over steep terrain. The errors of potential temperature θ and vertical velocity w are reduced most, by approximately 70% and 40%, respectively, in the HTF1 coordinate, with a monotonic increase in thickVL according to the increasing height; however, the errors of θ increased in all the other HTF coordinates, with nonmonotonic thickVLs. Furthermore, analyses of the errors of vertical pressure gradient force (VPGF) show that due to the interpolation errors of thickVL, the inflection points in the vertical transition of thickVL induce the initial VPGF errors; therefore, the HTF1 coordinate with a monotonic increase in thickVL has the smallest errors among all the coordinates. More importantly, the temporal evolution of VPGF errors manifests top-type VPGF errors that propagate upward gradually during the time integration. Only the HTF1 and HTF4 coordinates with a monotonic increase in thickVL near the top of the terrain can suppress this propagation. This optimized HTF coordinate (i.e., HTF1) can be a reference for designing a vertical thickVL in a numerical model. [ABSTRACT FROM AUTHOR]

Adoption of tethered-assist harvester technology on steep terrain by the forest industry has decreased workplace accidents. However, there are portions of harvest units that remain inaccessible to mechanized falling, therefore requiring manual falling as well. This study characterized the differences in terrain and forest conditions between manual and machine felled areas within the same harvest units. The hypothesis is that manual fallers will work more time in challenging terrain on harvest units using both mechanized and manual falling when compared to harvest units using manual falling only. This was tested using field data from three new harvest units, six previously harvested units, timber faller surveys, and harvest managers' interviews. For both field datasets, only slope was a statistically significant predictor of falling method. Further, both managers and fallers confirmed steep slope as one of the main reasons for requiring manual falling in addition to rocky bluffs, unstable terrain, and lack of access. This study indicates that when harvest units on steep terrain are felled with mixed falling methods, timber fallers likely work on steeper slopes than the machine, and spend a larger proportion of work hours on steeper ground than the average slope of a harvest unit. [ABSTRACT FROM AUTHOR]

The current use of photogrammetric systems with RPAS (remotely piloted aircraft systems) for the acquisition of topographic data in every type of coastal area has the benefit of a low risk for the personnel involved, good precision, increased productivity, and lower costs. However, their accuracy has not yet been researched in areas with steep terrain. In this paper, we study dune areas with slopes between 20 and 30%. The objective of this work is to examine the influence of the inclination of both the flight and the camera and to compare the results with those obtained using constant-height flights. With the data collected during three field campaigns, a total of 18 cases were studied. Among the results obtained, in the case of the horizontal flights, a vertical error of 0.048 m was detected for a 0° inclination of the camera versus an error of 0.086 m for a 10° inclination, thus an increase in the camera inclination decreased the accuracy by 44%. Moreover, the flight inclination did not lead to a significant reduction in the error. Therefore, as a main conclusion, the planning of horizontal flights as well as the non-tilt of the camera are recommended. [ABSTRACT FROM AUTHOR]

Active mobility projects can potentially initiate paradigm shifts in population and urban planning decision-makers. This paper aims to conduct a social cost-benefit analysis of an active mobility project in a Colombian city. The increase of physical activity, reduction of CO2 emissions, and traffic crashes were measured in an area with suitable slopes to promote bicycles for commuting. A social cost-benefit ratio of 1.14 was found, with physical activity and road safety as the most important outcomes of the active mobility infrastructure. Furthermore, a big room for the increase and promotion of cycling as a mode of transport is addressed. [ABSTRACT FROM AUTHOR]

Cable yarding is a well-established practice for wood extraction in mountainous regions in most parts of the world where fully mechanized harvesting systems like harvester-forwarder combinations cannot operate due to steep terrain. Work- and time-studies are most relevant to create productivity models for cost estimation, simulation, system development or simply to compare different harvesting systems. The present work investigates 70 work studies on cable yarding operations, regarding assessment methods to establish a knowledge base on cable yarding performance models. A comprehensive literature research was performed to identify relevant studies. Information about the investigated extraction campaigns regarding site specifics, stock specifics, the utilized equipment alongside the work-study-methods, as well as the statistical approaches for model creation were collected. The data gained and the associated models were systematically analyzed to compare different yarding systems concerning their performance. A set of 98 models was selected for this purpose. Productivity of the investigated systems ranges from 1.5 m3/PSH to 69.3 m3/PSH with a mean value of 9.8 m3/PSH where PSH represents the productive system hour. A meta-analysis was performed with the data that is presented in the literature found to test several hypotheses concerning the influence of different parameters on the performance of yarding systems. Various relationships are so strong that regression analysis with the meta-dataset, that is mostly containing mean values presented, results in significant correlations. The diversity in problem formulation and the corresponding diversity in methodical approaches account for limitations in comparability of performance. The consultation of guiding literature on forest work studies can promote comparability between studies. [ABSTRACT FROM AUTHOR]

Using the TRMM data and ERA5 reanalysis data, a heavy precipitation case in the eastern slope of the Qinghai-Tibet Plateau on July 6, 2006 was investigated. Based on the investigations, the precipitation structure characteristics in summer (June-August) over the eastern slope of the Qinghai-Tibet Plateau were analyzed. Results indicate that the heavy rain case on the eastern slope of the Qinghai-Tibet Plateau occurred in the typical circulation with convergence at the lower level and divergence at the upper level. The rain belt extends from northeast to southwest with the maximum rain rate over 20 mm·h-1. The echo top height of convective precipitation is more than 17 km while the echo top height of stratiform precipitation is no more than 15 km. There exists bright band structure at 6.5 km which is similar to the vertical structure of the stratiform precipitation on the non-plateau region. The statistical analysis shows that the summer precipitation frequency on the south-eastern Qinghai-Tibet Plateau and the connection area between eastern plateau and southern Sichuan Basin are high. In contrast, the frequency of the stratiform and convective precipitation are low on the north-eastern plateau and Sichuan Basin. The summer daily average precipitation shows similarity with precipitation frequency for the years. The characteristics of vertical structure of precipitation radar reflectivity factor are different in the various area. The vertical structures of precipitation radar reflectivity in the south-eastern and north-eastern regions of the Qinghai-Tibet Plateau are similar, but the vertical precipitation structures are different in the non-plateau regions because of the compression induced by the height of the topography. It is also found that there are some similarities between the vertical structure of precipitation in the connection area between eastern plateau and southern Sichuan Basin, the plateau and non-plateau regions. The vertical structure of convective precipitation in the Sichuan Basin, eastern China and tropical and sub-tropical ocean are mostly alike. The same conclusion can be found in the stratiform precipitation except for the height of the bright band is 1 km higher in the Sichuan Basin.

Forest roads, as a prerequisite for high-quality forest management, should be optimally distributed in order to avoid negative environmental impacts and to best fulfill their task. In the design phase of forest roads, it is necessary to know which factors influence most the volume of earthworks to enable the designer to best adapt to the terrain requirements. In this paper the impact of an average cross terrain slope and carriageway value of a forest road on cut and fill volume is analyzed. The research was carried out in the area of the management unit Trovrh–Kik, characterized by irregular terrain with slopes ranging between 27 and 58%, and on some micro locations even up to 84%. On eight forest roads, based on standard cross-section profiles, the influence of the average cross terrain slope and carriageway value (difference between ground level and grade level) of the forest road on the cut and fill volume per 1 m of the forest road route was analyzed. The obtained coefficients of determination indicate a strong correlation between the cut volume and carriageway value (R2 = 0.6841), and a moderate correlation between the fill volume and carriageway value (R2 = 0.5619). Unlike the influence of carriageway value on the cut and fill volume, the correlation between the cross terrain slope and fill volume is weak (R2 = 0.2076) or moderate in the case of the cut volume (R2 = 0.3167). On the basis of the analyzed standard cross-section profiles, it was determined that the carriageway value was 0.051 m, where the difference between the cut and fill volume was minimum and the average actual carriageway value was determined to be −0.09 m. It can be concluded that, on terrains with large and varying slopes, there is no unique model or terrain factor that could describe the earthworks required in the construction of a forest road. However, it is beyond doubt that the increase in the carriageway value and cross terrain slope caused the increase in the aforementioned volumes. [ABSTRACT FROM AUTHOR]

Cable-based yarding technology has had a long tradition on steep slopes in Europe, and the new implementation of yarding functions in recent decades favored operational efficiency and lower extraction costs. The main goal of this study was to evaluate the performance of the Syncrofalke 3t truck-mounted Processor Tower Yarder (PTY) on steep terrain, in coniferous forests managed with the shelterwood system. In particular, the aim was to determine PTY productivity and costs, with attention to parameters that could increase PTY effectiveness. The study was carried out in the Sredna Gora Mountains, Central Bulgaria, in pure Scots pine stand, with trees of average DBH = 34 cm and height = 22 m. The study was carried out in six corridors with 120 work cycles of tree extraction up the hill, 28° (53%). The mean productivity of PTY was 15.20 m3 per productive machine hour (PMH) and 12.29 m3 per scheduled machine hour (SMH) and was mainly influenced by the productivity of the yarder unit. Under the given conditions, the performance of PTY significantly increased if more than one tree (at least two trees) were attached and extracted per yarder cycle, since the productivity of the processor was approximately twice that of the yarder. The gross costs of the studied PTY were calculated at 297.48 EUR PMH−1 and 16.17 EUR m−3. The variable costs (75%) predominate in the net costs distribution, followed by the fixed costs (15%) and the labor costs (10%). The time, productivity and cost results obtained showed the high efficiency and level of integration of PTY operations in order to achieve economic efficiency of logging in montane pine forest managed in a shelterwood system. [ABSTRACT FROM AUTHOR]

The rural typology of the settlements in Ohrid is usually of a compact type, placed in flat or hilly areas. The settlements in the hilly areas are formed according to the configuration of the terrain, usually within a steep terrain (the villages of Ramne, Velestovo, Racha). The location of the settlements was created according to the needs of the newly settled families at the period. It was necessary to have arable land in the surrounding area, to satisfy the needs of the occupation of the families, for example for fishing (the villages of Peshtani, Trpejca, Konjsko, Ljubanishta), for agriculture (the villages of Lakocheraj, Orman), livestock farming (the villages of Velestovo, Ramne) etc. The families carried with them certain traditional beliefs regarding the shape and size of the house, and with that a certain appearance of the settlement was formed. The surrounding landscape dominated, with the forest areas that were in the immediate vicinity of the settlement, comfortable conditions were created for the life and prosperity of the families. At the end of the 18th century, the settlements were small, with a small number of houses while in the 19th and 20th centuries, new families settled more intensively in the area. There was visible increase in the number of houses and the number of the population. [ABSTRACT FROM AUTHOR]

Cable-based technologies are the backbone of timber harvesting on steep slopes. To simplify the cable road design process, the QGIS plugin Seilaplan was recently developed. Seilaplan is tailored for Central European cable yarder technology, with standing skylines. To analyze and predict the load path and occurring forces, the close-to-catenary Zweifel approach is implemented in Seilaplan. The aim of this study was to validate the catenary analyses (deflection and skyline tensile force) under realistic, heavy load conditions for multi-span cable roads. The main finding is that sufficient accuracy, for practical applications under real loading configurations and cable road settings, can be achieved by applying the Zweifel approach. This holds for both the predicted static skyline tensile force, for which a deviation of −3.5 % to +12.7 % was measured (root mean square error [RMSE] = 7 kN), and for the deflection, which deviated from measured values by −0.73 m to +0.9 m (RMSE = 0.5 m). A slight limitation of the implemented Zweifel approach is the missing aspect of the mainline loading, in particular for steep spans. [ABSTRACT FROM AUTHOR]

The current use of photogrammetric systems with RPAS (remotely piloted aircraft systems) for the acquisition of topographic data in every type of coastal area has the benefit of a low risk for the personnel involved, good precision, increased productivity, and lower costs. However, their accuracy has not yet been researched in areas with steep terrain. In this paper, we study dune areas with slopes between 20 and 30%. The objective of this work is to examine the influence of the inclination of both the flight and the camera and to compare the results with those obtained using constant-height flights. With the data collected during three field campaigns, a total of 18 cases were studied. Among the results obtained, in the case of the horizontal flights, a vertical error of 0.048 m was detected for a 0° inclination of the camera versus an error of 0.086 m for a 10° inclination, thus an increase in the camera inclination decreased the accuracy by 44%. Moreover, the flight inclination did not lead to a significant reduction in the error. Therefore, as a main conclusion, the planning of horizontal flights as well as the non-tilt of the camera are recommended.

One of the basic requirements for sustainable forest management in mixed broadleaved stands is to provide suitable conditions for natural regeneration of trees. These conditions include, but are not limited to, the frequency, quality and the composition of seedling species. Compacted soil layers caused by forest machinery traffic are the most common problem affecting seedling establishment and growth after skidding operations. In this study, we evaluated the frequency, quality, diversity of seedling species and physicochemical properties of soil on 10-, 20- and 30-year-old abandoned skid trails. Further comparison to the values of the mentioned above parameters in control areas allowed for the evaluation in terms of natural recovery processes, under varying traffic intensity and the longitudinal slope of the skid trails in a mixed broadleaved forest. Results showed that there is a significant positive trend of recovery for soil physicochemical properties and ecological characteristics (density and quality) of seedling growing on the skid trails. The time required to recover soil properties and ecological attributes of seedlings increased with increasing traffic intensity and slope of the skid trail. Our results showed that it takes 20 and 30 years to fully recover the chemical and physical properties of the soil, respectively. On the 30-year-old skid trails, density and species diversity indices were fully recovered, but the quality of the seedlings was not restored to the control conditions. The results suggest the importance of a proper planning of the skid trail network, avoiding in particular skid trails with a slope gradient higher than 20%. [ABSTRACT FROM AUTHOR]

Cable yarding remains an important option in steep terrain timber harvesting, a reason for which new or improved operational efficiency models are required to support science and practice. Developed traditionally, these models are known to require many resources, a reason for which new approaches to the problem were researched lately, mainly by the use of Global Navigation Satellite System (GNSS) data, spatial and statistical inference systems. This study evaluates the possibility of using GNSS data and machine learning techniques to classify important cable yarding events in the time domain. Three classes were assumed by the study as being relevant for cable yarding operational setup, namely carriage moving in the uphill (MU) and downhill (MD) directions, as well as carriage stopped (S). Data collected by a consumer-grade GNSS unit was processed to extract some differential parameters which were coupled with GNSS motorial and geometric features to feed a Multi-Layer Perceptron Neural Network with Back propagation (MLPNNB) in a pre-evaluation phase which aimed at mining the data structure as a strategy to develop the best MLPNNB configuration for training and testing. Leg distance, difference in elevation, speed of the carriage, and difference in heading were used together and interchangeably in this phase, based on logical assumptions. As a result of pre-evaluation, a MLPNNB using all these datasets was found to be the best scenario. Based on this outcome, the data was split into a training (70%) and a testing (30%) subset, then the MLPNNB was used to learn and generalize on these subsets. The main results indicate that the MLPNNB had an excellent performance, with a classification accuracy of 98.7, 98.4, and 98.8% in the pre-evaluation, training, and testing phases, respectively. Log-loss errors were also found to be very low (5, 5.9 and 4.1%, respectively), indicating a high generalization capability of the MLPNNB model. Based on the results, the main conclusion of the study is that original and derived GNSS data coupled with machine learning techniques could prove to be an important tool for operational monitoring and cable yarding efficiency model development, mainly due to the possibility of working with large amounts of data. [ABSTRACT FROM AUTHOR]

Copyright of Journal of the Japan Forest Engineering Society is the property of Japan Forest Engineering Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to reduce greenhouse gas emissions, low emission or zero-emission technologies have been applied to light and heavyduty vehicles by adopting electric propulsion systems and battery energy storage. Hybrid cable yarders and electrical slack-pulling carriages could represent an opportunity to increase the energy efficiency of forestry operations leading to lower impact timber harvesting and economic savings thanks to reduced fuel consumption. However, given the limited experience with hybrid-electric systems applied to cable yarding operations, these assumptions remain uncertain. This study assessed an uphill cable yarding operation using a hybrid cable yarder and an active slack-pulling electric power carriage over thirty working days. A total of 915 work cycles on four different cable lines were analysed. Longterm monitoring using Can-BUS data and direct field observations were used to evaluate the total energy efficiency, total energy efficiency (%), and fuel consumption per unit of timber extracted (L/m3). The use of the electric-hybrid system with a 700 V supercapacitor to store the recovered energy made it possible to reduce the running time of the engine by about 38% of the total working time. However, only 35% to 41% of the Diesel-based mechanical energy was consumed by the mainline and haulback winches. Indeed, the remaining energy was consumed by the other winches of the cable line system (skyline, strawline winches and carriage recharging or breaking during outhaul) or dissipated by the system (e.g., by the haulback blocks). With reference to all work cycles, the highest net energy consumption occurred during the inhaulunload work element with a maximum of 1.15 kWh, consuming 70% of total net energy consumption to complete a work cycle. In contrast, lower energy consumption was recorded for lateral skid and outhaul, recording a maximum of 23% and 32% of the total net energy consumption, respectively. The estimated recovered energy, on average between the four cable lines, was 2.56 kWh. Therefore, the reduced fuel need was assessed to be approximately 730 L of fuel in the 212.5 PMH15 of observation, for a total emissions reduction of 1907 kg CO2 eq, 2.08 kg CO2 eq for each work cycle.

The growing interest in accessing steep terrain is pushing the expansion of the operating range of ground-based machines through winch-assist technology. However, cable tensile forces remain a major concern in the advancement of this technology. In this study, cable tensile forces in a winch-assist harvesting operation based on an anchor machine configuration were investigated. A harvesting machine tethered on ground slopes of up to 103% (45.9°) was observed over four days. Cable tensile forces were recorded at both the harvesting and anchor machines, at a frequency of 100 and 10 Hz, respectively. Cameras and GNSS devices enabled the execution of a time and motion study and the recording of machine positions. At the harvesting machine, peak tensile forces of up to 400 kN were recorded. Downhill movements of the harvesting machine were the cause of the highest peaks which, however, never exceeded the endurance limit of the cable. Numerous local variations in cable tensile forces exceeded 50 kN for just a few hundredths of a second, with a maximum variation of 300 kN in less than a second. Movements of the harvesting machine were the main cause of the major local variations. Depending on work element and harvesting machine movements, cable tensile forces were higher at either the harvesting or anchor machines; however, the highest peak tensile forces per work element and the related working loads were always recorded at the harvesting machine. Some implementation steps for improving the safety of winch-assist harvesting operations using anchor machines are also discussed. [ABSTRACT FROM AUTHOR]

The eastern periphery of the Tibetan Plateau (EPTP) is prone to frequent and severe Persistent Extreme precipitation (PEP) events in summer. Given the complexity of weather systems and the intricate nature of terrain over this region, the generation and development mechanisms of the PEP in the EPTP remain to be determined. In this study, the formation and persistence mechanisms are further explored from the perspective of the general features of large-scale circulations, moisture source diagnosis and the influence of steep topography by using a thermal-dynamical diagnosis method, a mesoscale numerical simulation and a Lagrangian identification of the main moisture sources. The results show that during PEP events, the corresponding atmospheric circulation systems are characterized by an anomalous Rossby wave train at middle levels, an intensified westerly jet, an eastward extension of the South Asian high and a westward extension of the western Pacific subtropical high, all of which are possible to facilitate the development of potential instability and anticyclonic convergence of water vapor transport. The evaporative moisture sources from the Southeastern Asia (SEA), Bay of Bengal (BOB), and Southern China Sea (SCS) are remarkably enhanced during PEP events, with a contribution of 56.44%, which is 28.5% higher than the climatic mean. The further sensitive experiment indicates that the steep terrain could enhance the continuous transport of positive potential vorticity and the downward propagation of upper-level isentropic potential vorticity disturbances, thereby playing an essential role in the triggering and development of PEP events. • The synoptic circulation patterns are identified for PEP events over the EPTP. • The SEA, BOB, and SCS acts as the main enhanced moisture source contributors. • The steep terrain facilitates the transport of potential vorticity disturbances. [ABSTRACT FROM AUTHOR]

The paper presents the conception and design of the hydraulic transmission for agricultural machine appropriate for the treatment of extreme steep farmland. The small IC diesel engine powers a hydraulic pump that feeds the drive system as well as all working accessories. Hydraulic transmission systems perfectly satisfy the basic condition about the lowest weight but initially, they require totally new management. This paper outlines a simple but effective management system consisting of basic valves, electric sensors, and switches, which fits perfectly this specialized machine. The management enables the use of the potential energy for powering the accessories. When climbing up and downhill, the power is automatically distributed to the driving wheels or a winch, depending on the situation on the terrain. Significant working situations of the machine are predicted and analyzed. The appropriate function diagrams, hydraulic schemas and analytical calculations are presented. To raise the efficiency of the machine the close and the open hydraulic circuits are treated and analyzed. The machine is prototyped and partially tested. The results confirmed a big fuel saving of about 30 percent as predicted.

Cable yarding is an inherently expensive extraction technology, but the mainstay for mountain forest management. Fuel cost represents a considerable share of total harvesting costs. Energy-recuperating, electrical slack-pulling carriages (EC), which recuperate energy during lateral yarding and store it as electrical energy in super-capacitors for powering slack-pulling during the subsequent yarding cycle have emerged only recently. Fuel consumption of cable yarding is expected to be lower when ECs are employed compared to working with conventional, diesel engine-powered slack-pulling drive (DC) carriages. To determine if reality matched expectations, a time and motion study was conductedduring which fuel consumption was extracted from the engine control systems using custom-made dataloggers for an uphill whole tree yarding operation in Austria. Average productivity was 21.9 m³ per productive system hour excluding delays (m³ PSH0 -1) at 0.89 m³ average tree volume and 58.4 m average yarding distance. Productivity was modeled as a function of average tree volume, yarding distance and lateral yarding distance. Average fuel consumption was 1.27 ± 0.97 l m-3 (DC) and 0.88 ± 0.56 l m-3 (EC). In the DC treatment, the carriage engine accounted for 9% of the total fuel consumption. Modeling revealed that fuel consumption depended on average tree volume, yarding distance, lateral yarding distance and carriage type as originally postulated. The latter effect interacted with that of average tree volume and EC's advantage in fuel consumption was limited by a break-even average tree volume. In conclusion, the EC has the potential to improve profit margins in small-tree operations through lower fuel consumption. [ABSTRACT FROM AUTHOR]

This article proposes a novel polarization orientation angle (POA) estimation algorithm for steep terrain by applying physical scattering characteristics of natural surface. The algorithm extends the range of POA from [−45°, 45°] to (−90°,90°] and achieves consistent estimation with the widely used circular polarization algorithm (CPA) and minimum cross-polarization algorithm (MXPA) over flat area, but avoids the POA wrapping caused by the restriction of CPA and MXPA over precipitous area. Besides, detailed comparison among these deorientation algorithms is presented for clarifying their relations and analyzing the wrapping and unwrapping issue of POA. Both simulated data of Bragg scattering model and PolSAR data of L-band ALOS PALSAR and P-band NASA/JPL AIRSAR are used to substantiate the proposals. [ABSTRACT FROM AUTHOR]

In the steep terrain of the European Alps, cable yarding still plays an important role. To maintain low costs of timber harvesting and improve the productivity of cable yarding operations, system integration by mounting of a tower yarder, crane, and processing unit onto a single carrier is the major pathway of innovation. In particular, under mountainous conditions, with small landings at the forest road and high production rates, cable yarding systems require well-coordinated transport to available storage space at the landing. Otherwise, the operation will run out of storage space and be shut down until serviced by a log truck. To investigate the system behavior and determine the overall performance effects, an agent-based simulation model was developed. The impact of the storage capacities, number of trucks employed, weather conditions, and timing of truck orders were evaluated. Cable yarders, trucks, and individual yarding lines form a population of agents placed in the spatial model environment, acting as the top-level agent. To harvest and transport an assumed volume of 52,500 m3 of timber from 65 different harvesting sites with 150 yarding lines, 301 days are required, in the best case. For the worst case, 484 days are required to complete all operations. Early information flow of the storage level at the landing saves a majority of the waiting cost if the storage capacity at the road is low and the number of trucks high, with 2.5 € m−3. The results also show that adopting measures to increase the storage capacity at the landing will lead to less sensitive reactions in the supply chain. [ABSTRACT FROM AUTHOR]

Cable logging is a common harvesting technique for steep slope conditions, despite the safety hazard for the operators, which is mainly related to failure of cables or anchor trees. The multiple factors that determine whether a tree should be considered as an anchor make it difficult to estimate the actual suitability of the anchor tree from a safety perspective during logging. To address this critical question, the mechanical response of natural anchors was monitored in nine cable logging sites using a standing skyline system. Different anchoring methods were observed, namely, tieback anchors, multiple in-line anchors and single tree anchors. Based on previous experience regarding tree stability assessment, an innovative continuous monitoring technique was applied at each research site. The mechanical response of the anchors was analyzed in terms of force-rotation curves, which summarize the effects of loads transmitted by the skyline. An elastic response was observed in nearly all anchors, but the magnitude of the rotation varied depending on the anchoring method and the applied force observed during the survey. Effects due to cyclic loading were analyzed in four of the case studies, and an apparent relaxation phenomenon at the root-plate system was observed. Finally, the research provides an estimation of the anchor's stability with respect to their maximum theoretical resistance, evaluated from trees showing similar characteristics that have previously been tested. Results from these field measurements provide information that can improve guidance regarding the holding strength of anchors to current empirical methods and help ensure safety anchoring methods. [ABSTRACT FROM AUTHOR]

Cable-assisted (or tethered) mechanized harvesting has recently been introduced to the Pacific Northwest of the United States, and is rapidly being adopted by the forest industry. However, potential environmental impacts, productivity and cost of the new harvesting systems have not been well-assessed. This study aims to examine the effects of cable assistance on soil compaction, system productivity and cost through a field-based experiment. A harvester-forwarder system was used to thin a harvest unit on dry soils in western Oregon, with and without cable-assistance. We conducted a detailed time study during operations and collected soil measurements before and after machine passes. Machine productivity ranged from 28.75 to 92.36 m3 per scheduled machine hour, with resulting unit costs for untethered and tethered systems ranging from $13.19 to $18.13/m3. Our results showed reduced soil impacts in both extent and degree of soil compaction when cable assistance was employed. The reduced extent of soil impacts is attributed to a reduction in track wander owing to the operative tensions of the tether cable, and the smaller increase in soil density appears to be attributed to combined effects of initially denser soil conditions and reduced shear displacement as a result of cable-assistance. [ABSTRACT FROM AUTHOR]

This study aims to define a simple and effective method to calculate skidding distances on steep karst terrain, rich in ground obstacles (stoniness and rockiness) to support decision planning of secondary and primary forest infrastructure network for timber extraction in productive selective cut forests. Variations between geometrical extraction distances and actual distances were highlighted on the operational planning level (i.e., compartment level) through GIS-related calculation models, focusing on cable skidder timber extraction. Automation in defining geometrical and real extraction distances, as well as relative forest openness were achieved by geo-processing workflows in GIS environment. Due to variation of extraction correction factors at the compartment level from a minimum of 1.19 to a maximum of 5.05 in the same management unit, it can be concluded that planning harvesting operations (timber extraction) at operational level should not include the use of correction factors previously obtained for entire terrain (topographical) categories, sub-categories or even management units.

Extraction process of wood raw materials, from forest stand to the nearest forest road, is very difficult and expensive stage having highest environmental damages. Forestry activities where limited to the use of technology have great importance in terms of technical, economical, ergonomic and environmental in mountainous terrain especially. The aim of this study is to develop an economic and ergonomic system to ensure the transport of logs to the nearest forest path by cable line and also to provide an alternative skyline system to existing costly methods in air transportation. In our country, the only method used to transport of logs in the air is the forest airlines. Differences of the proposed system from other airlines (expensive and imported) are more simple, ergonomic and economic. Thus, possible damages in both logs and environment will be minimized during the transportation and an ergonomic work will be done. In this system, drummed forest tractor was used for the power supply and 10-12 mm thickness steel cable as main cable was used. Locking wagon on the main cable was produced in special mechanic industry and it was integrated to the system. This wagon has 6-8 mm thicknesses ground cable and process of pulling the timber up to the forest road by cable wrapped to drum was completed. Ring system is used in the pulling of logs to uphill direction. Installation procedures of this system in the field can be performed in a very short period as a few hours in a simple manner. This research was tested in Mountainous Eastern Black Sea Region at the field condition formed conifer forest in the spring 2016. Controlled pulling to upward by using engine power was taken essential. Based on this study, drawing speed and efficiency on the motor system were found 1,05 m/s and 3,057 m3/h, respectively. Average skidding distance was 140 meter in both cases. Previously imported heavy forest airlines are not being profitable due to high depreciation price and inappropriate for the magnitude work. This system to be developed will be the first in our country. According to the forest airlines used in this world, the advantages are as follows: The tower is not required, practical, cheaper and portable, and it does not need a big drum.

This study analysed the skyline tensile forces in 502 complete work cycles during ordinary cable logging operations on 12 different cable lines in the Italian Alps. The objectives of the research were to quantify the frequency of exceeding the recommended safe working limits and to determine the skyline peak tensile forces and dynamic amplifications, as well as their explanatory variables. Data collection was based on skyline tensile force monitoring synchronized with the video recording of the logging operations and the monitoring of the carriage positions. The load volumes were measured at the landing, and the total loads were estimated for each cycle. The results showed 55% of the work cycles exceeding the safe working load. The highest peak tensile forces were often recorded while starting the load moving during lateral skid. High-peak tensile forces were also recorded during inhaul, where the tensile forces were amplified by the cyclic load behaviour. It appears that some operators underestimate the effects of pretension, payload, and cable line geometry on the magnitude of the skyline tensile force. The complexity in identifying reliable theoretical models inclusive of dynamic amplifications and the inefficacy of the load limiters installed on the machines highlighted the need to improve the best practices within the operators, and to adopt technical solutions for the continuous skyline tensile force monitoring during ordinary cable logging operations. [ABSTRACT FROM AUTHOR]

Cable cranes are among the most important means of yarding and transporting timber in many mountainous regions of Europe. In the last decade, all-terrain mobile tower cable cranes have been increasing due to their adaptability to operate both in uphill as well in downhill configuration. This research assesses the efficiency and the costs of a mobile cable crane manufactured in Czech Republic and designed for all-terrain application and specifically mounted on a wheeled agricultural tractor. A total of 100 cycle times were recorded in order to obtain evaluate the performance in the downhill as well uphill extraction configuration. The productivity analysis was based on regression equation as a function lateral distance, skyline slope distance and extracted volume. Increasing in number of lateral distance and extraction distance resulted as significant variables affecting the cycle time. Even if the test highlights a good efficiency of the extraction system for both the configuration (uphill vs downhill) there a still many organisational features that could be improved in order to fully exploit the potentiality of the tested cable crane system.

Unmanned aerial vehicle (UAV) photogrammetry is one of the most effective methods for capturing a terrain in smaller areas. Capturing a steep terrain is more complex than capturing a flat terrain. To fly a mission in steep rugged terrain, a ground control station with a terrain following mode is required, and a quality digital elevation model (DEM) of the terrain is needed. The methods and results of capturing such terrain were analyzed as part of the Belca rockfall surveys. In addition to the national digital terrain model (NDTM), two customized DEMs were developed to optimize the photogrammetric survey of the steep terrain with oblique images. Flight heights and slant distances between camera projection centers and terrain are analyzed in the article. Some issues were identified and discussed, namely the vertical images in steep slopes and the steady decrease of UAV heights above ground level (AGL) with the increase of height above take-off (ATO) at 6%-8% rate. To compensate for the latter issue, the custom DEMs and NDTM were tilted. Based on our experience, the proposed optimal method for capturing the steep terrain is a combination of vertical and oblique UAV images.

Turbulent flow fields over a two-dimensional steep ridge and three-dimensional steep hill with rough and smooth surfaces are investigated by using a delayed detached-eddy simulation (DDES) with the specified height as a new control parameter. The applicability of typical turbulence models in previous studies is evaluated by using validation metrics. While all turbulence models simulate the turbulent flow fields over the steep rough terrain well, the k − ε model overestimates the mean wind speed and underestimates the turbulent kinetic energy over steep, smooth terrain. The large-eddy simulation captures the large-scale vortices and improves the mean wind speed, but overestimates the turbulent kinetic energy due to the inaccurate specification of the surface roughness. The detached-eddy simulation considering the surface roughness shows further improvement, but still overestimates the turbulent kinetic energy, since the region using the Reynolds-averaged Navier-Stokes model is too thin. The modified DDES model with a new control parameter is suitable for the prediction of the mean wind speed and turbulence as demonstrated by the visualization of instantaneous flow fields through vortex cores, and a quadrant analysis to examine the organized motion, with strong organized motions identified in the wake region of smooth terrain. Roller vortices are significant on the lee side of the two-dimensional smooth ridge, while horseshoe vortices appear in the wake region of the three-dimensional smooth hill. [ABSTRACT FROM AUTHOR]

This study aims to define a simple and effective method to calculate skidding distances on steep karst terrain, rich in ground obstacles (stoniness and rockiness) to support decision planning of secondary and primary forest infrastructure network for timber extraction in productive selective cut forests. Variations between geometrical extraction distances and actual distances were highlighted on the operational planning level (i.e., compartment level) through GIS-related calculation models, focusing on cable skidder timber extraction. Automation in defining geometrical and real extraction distances, as well as relative forest openness were achieved by geo-processing workflows in GIS environment. Due to variation of extraction correction factors at the compartment level from a minimum of 1.19 to a maximum of 5.05 in the same management unit, it can be concluded that planning harvesting operations (timber extraction) at operational level should not include the use of correction factors previously obtained for entire terrain (topographical) categories, sub-categories or even management units. [ABSTRACT FROM AUTHOR]

This study aims to define a simple and effective method to calculate skidding distances on steep karst terrain, rich in ground obstacles (stoniness and rockiness) to support decision planning of secondary and primary forest infrastructure network for timber extraction in productive selective cut forests. Variations between geometrical extraction distances and actual distances were highlighted on the operational planning level (i.e., compartment level) through GIS-related calculation models, focusing on cable skidder timber extraction. Automation in defining geometrical and real extraction distances, as well as relative forest openness were achieved by geo-processing workflows in GIS environment. Due to variation of extraction correction factors at the compartment level from a minimum of 1.19 to a maximum of 5.05 in the same management unit, it can be concluded that planning harvesting operations (timber extraction) at operational level should not include the use of correction factors previously obtained for entire terrain (topographical) categories, sub-categories or even management units. [ABSTRACT FROM AUTHOR]

Forest attributes such as tree heights, diameter distribution, volumes, and biomass can be modeled utilizing the relationship between remotely sensed metrics as predictor variables, and measurements of forest attributes on the ground. The quality of the models relies on the actual relationship between the forest attributes and the remotely sensed metrics. The processing of airborne laser scanning (ALS) point clouds acquired under heterogeneous terrain conditions introduces a distortion of the three-dimensional shape and structure of the ALS data for tree crowns and thus errors in the derived metrics. In the present study, Procrustean transformation and histogram matching were proposed as a means of countering the distortion of the ALS data. The transformations were tested on a dataset consisting of 192 field plots of 250 m2 in size located on a gradient from gentle to steep terrain slopes in western Norway. Regression models with predictor variables derived from (1) Procrustean transformed- and (2) histogram matched point clouds were compared to models with variables derived from untransformed point clouds. Models for timber volume, basal area, dominant height, Lorey’s mean height, basal area weighted mean diameter, and number of stems were assessed. The results indicate that both (1) Procrustean transformation and (2) histogram matching can be used to counter crown distortion in ALS point clouds. Furthermore, both techniques are simple and can easily be implemented in the traditional processing chain of ALS metrics extraction. [ABSTRACT FROM AUTHOR]

New techniques have recently appeared that can extend the advantages of grapple yarding to fast-growing plantations. The most promising technique consists of an excavator-base un-guyed yarder equipped with new radio-controlled grapple carriages, fed by another excavator stationed on the cut-over. This system is very productive, avoids in-stand traffic, and removes operators from positions of high risk. This paper presents the results of a long-term study conducted on 12 different teams equipped with the new technology, operating in the fast-growing black wattle (Acacia mangium Willd) plantations of Sarawak, Malaysia. Data were collected continuously for almost 8 months and represented 555 shifts, or over 55,000 cycles—each recorded individually. Production, utilization, and machine availability were estimated, respectively at: 63 m3 per productive machine hour (excluding all delays), 63% and 93%. Regression analysis of experimental data yielded a strong productivity forecast model that was highly significant, accounted for 50% of the total variability in the dataset and was validated with a non-significant error estimated at less than 1%. The figures reported in this study are especially robust, because they were obtained from a long-term study that covered multiple teams and accumulated an exceptionally large number of observations. [ABSTRACT FROM AUTHOR]

Urban sprawl in underdeveloped countries can become a catastrophic problem when it occurs on environmentally unstable ground. Urban geomorphology is the science that studies the urban sites due to the bias of the relief features and its interrelations with other components of the landscape, such as climate, meteorology, geology, vegetation and use and occupation. Based on the geo-environmental design of the urban landscape using geoprocessing, remote sensing and empirical analysis, this research aims to portray the geomorphological interface of the Areia-PB urban site and, specifically, to identify landscapes of urban risk through the geosystemic matrix. As a result, there are areas with irregular occupation and fragile constructions on steep terrain. It is plausible that this research will direct and enable others, which will deepen the surveys of the problems of territorial planning of the urban site of Areia and can subsidize urban public policies. [ABSTRACT FROM AUTHOR]

Copyright of Indonesian Journal of Forestry Research is the property of Indonesian Journal of Forestry Research and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)