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Kosmos
Astronomia Astrofizyka
Inne

Kultura
Sztuka dawna i współczesna, muzea i kolekcje

Metoda
Metodologia nauk, Matematyka, Filozofia, Miary i wagi, Pomiary

Materia
Substancje, reakcje, energia
Fizyka, chemia i inżynieria materiałowa

Człowiek
Antropologia kulturowa Socjologia Psychologia Zdrowie i medycyna

Wizje
Przewidywania Kosmologia Religie Ideologia Polityka

Ziemia
Geologia, geofizyka, geochemia, środowisko przyrodnicze

Życie
Biologia, biologia molekularna i genetyka

Cyberprzestrzeń
Technologia cyberprzestrzeni, cyberkultura, media i komunikacja

Działalność
Wiadomości | Gospodarka, biznes, zarządzanie, ekonomia

Technologie
Budownictwo, energetyka, transport, wytwarzanie, technologie informacyjne

Mathematical and Computational Forestry & Natural-Resource Sciences (MCFNS)

Ground based systems are the main approach used for off-road timber transportation throughout the world. Estimates of terrain transportation costs are required for several forest planning problems and for assessment of harvesting contracts and forest land values. Methods for these calculations can be categorized into two groups. Methods based on average transportation distance predate computers, are analytical, and based on manual calculations. Network methods are based on a digital raster representation and are solved with numerical computations. Here, the two categories are compared and linked. Analytical methods in the literature have been limited to flat terrain and including detail is difficult. The network method can be extended to include uneven terrain or detailed input data.

http://mcfns.com/index.php/Journal/article/view/6_48 2014/10/02 - 10:18

A new distance-based estimator for forest regeneration assessment, the mean distance method, was developed by combining ideas and techniques from the wandering quarter method, T-square sampling and the random pairs method.  The performance of the mean distance method was compared to conventional 4.05 square meter plot sampling through simulation analysis on 405 square meter blocks of a field surveyed clumped distribution and a computer generated random distribution at different levels of density of 100, 50 and 25%.  The mean distance method accurately estimated density on the random populations but the mean distance method estimates were more variable than those of 4.05 square meter plot sampling.  The mean distance method overestimated actual density and was less precise than plot sampling when both methods were tested on the clumped populations.  The optimum sample sizes needed for the mean distance method to achieve the same precision as 4.05 square meter plot sampling at all three density levels, for both the random and clumped spatial distributions, were at least 10 times larger than the sample size used for 4.05 square meter plot sampling.

http://mcfns.com/index.php/Journal/article/view/6_54 2014/10/02 - 10:18

This short summary represents the introduction and overview of a special section of two papers that arose from the 2013 (9th) Southern Forestry and Natural Resources GIS Conference (SOFOR GIS). The conference held its ninth meeting in Athens, Georgia (USA) on December 9-10, 2013.

http://mcfns.com/index.php/Journal/article/view/6_62 2014/10/02 - 10:18

We describe here a case study in compiling a high-resolution forest inventory for central Georgia using the K-nearest neighbor approach with multi-source data and Mean Balancing correction for the estimation bias. In general, multi-source data collected through various incompatible designs cannot be mixed due to intractable variances and unknown bias. Because of this incompatibility abundant information about the environment (i.e. atmospheric conditions, soil composition, spatio-temporal data from nearly 40 years of satellite imaging, and a wealth of site specific studies with sampling for various growth attributes) frequently cannot be used to produce new unbiased estimates for the variables and areas of interest. This study was carried out in central Georgia, and the k-NN approach was used to fuse together various incompatible data from public and private sources. We used the Mean Balancing approach to remove the bias resulting from this data fusion. The result of the study is a derivation of an unbiased high-resolution forest inventory, which can be used for small area's fiber supply assessment analysis.

http://mcfns.com/index.php/Journal/article/view/6_65 2014/10/02 - 10:18

The September 1, 1894 fire near Hinckley, Minnesota has well documented accounts from many survivors that allow position of the flame front to be established for a number of times throughout the fire. FARSITE is a modern fire spread rate simulation model requiring spatial layers of elevation, slope aspect, timber type, and derived layers of fuel type, crown cover, stand height, crown base height, crown bulk density, duff and coarse woody debris. We combined present GIS data, historical map data, and present ecosystem properties to provide data needed for these layers. GIS output of FARSITE spread predictions were used to match flame front position to eyewitness accounts and model parameters were altered to produce a flame front location and time that matched eyewitness location and timing.

http://mcfns.com/index.php/Journal/article/view/6_80 2014/10/02 - 10:18

WIS.2 is a DSS for monitoring and implementing the goal-oriented and sustainable managementof forest ecosystems, especially with regard to the integral management of signicant spatial andtemporal scales in forest ecosystems. WIS.2 considers multiple ecosystem goods and services in silviculturalmanagement and the implementation of silvicultural interventions, which are in accordance with theSwiss silvicultural tradition. WIS.2 takes a top-down approach, starting with the entrepreneurial strategy,and ending at short and mid-term interventions at stand level. WIS.2 structures the overall decision processacross multiple scales and provides decision support for each decision to be taken by organizing andconnecting available data and models.WIS.2 is based on MS Access and ArcGIS View and is composed of dierent applications, each handling amain aspect of the management of forest ecosystems. The tool is used at the level of higher education inforest management in Switzerland. WIS.2, initially developed during 2001-2005 within the framework of aPhD thesis at the ETH in Zurich (\Author" 2005a), has been successively improved through practical usein more than 10 case studies in ve Swiss Cantons. The main challenge is now to advance from a prototypeto an easily available consolidated IT product.

http://mcfns.com/index.php/Journal/article/view/6_89 2014/10/02 - 10:18

Fuel treatment is an important component of wildland fire management. This research revised and applied a mathematical programming model to schedule fuel treatment to fragment fuel patches with high fire intensity hazard. It differs from many previous fuel treatment scheduling models that aimed at detailed fire spread control. This new approach does not rely on the accurate prediction of future fire spread direction, speed and duration. Preliminary analyses suggested that scheduling fuel treatment to fragment high fire hazard fuel patches has similar effects as scheduling fuel treatment to control fires with very long fire duration. Both modeling strategies could effectively lower the risk of future fires with various spread directions, spread speeds and durations. Tests also suggested that fuel treatment layouts designed to control fires with short durations might not perform well when the actual fire duration is much longer that it is planned for. This research presented a new and practical approach in patch oriented fuel management.

http://mcfns.com/index.php/Journal/article/view/6_1 2014/04/23 - 18:04

Adjacency constraints along with harvest volume constraints are important in long term forest management planning. Simulated annealing (SA) has previously been successfully applied when addressing such constraints. The objective of this paper is to assess the performance of SA using three methods for generating candidate solutions. Biased probabilities in the management unit (MU) selection were introduced, one static and one dynamic. The rst one (Method 1) is the conventional (static) method. The two other methods were implemented through a search vector used in the candidate solution generator. These methods are based on (Method 2) the number of treatment schedules and standard deviation of NPV within MUs and (Method 3) the MU's potential improvement in the objective function value, the number of URM adjacency violations an MU is involved in, the period specic volume harvested in an MU and the number of times an MU is selected. The methods were tested on a large number of datasets including 300 hypothetical forest landscapes characterized by three dierent initial age class distributions, respectively young, normal and old. Evaluation of the methods was accomplished by means of objective function values and rst feasible iteration. Solutions improved when introducing bias in the probabilities for MU selection (Methods 2 and 3) compared to the conventional method (Method 1) and when the probability bias for selecting MUs is dynamic (Method 3) rather than static (Methods 1 and 2). The mean improvement for the average GAP obtained by Method 3 for young, normal and old forest landscapes was 20.88%, 12.84% and 5.20%, respectively. Whereas for the minimum GAP the mean improvement was 21.96%, 14.30% and 6.05% for young, normal and old forest landscapes, respectively.

http://mcfns.com/index.php/Journal/article/view/6_11 2014/04/23 - 18:04

When a plant living in an unpredictable environment produces seeds, its ideal strategy might not be to have all seeds germinate at once. What is the germination fraction that will maximize a plant's fitness, allowing the plant to hedge its bets in case of a poor year? To answer this question, in his now classic 1966 paper, Dan Cohen worked out the optimal annual germination fraction for seeds in a fluctuating environment. His result was elegant, but relied on a series of simplifying assumptions. We focus here on two specific assumptions. Namely, Cohen assumed that the population consists of annual plants, which have no adult age-structure, and that a seed's age has no effect on whether or not it will germinate. We review empirical and theoretical papers that have considered what happens when one or both of these assumptions is relaxed. More than a half-century has passed since Cohen's landmark study, and yet the existing literature has yet to provide theoretical solutions for perennial species as Cohen was able to do for annuals. Empirical studies have addressed short-lived perennials with minimal seed dormancy. However, perennials with longer lifespans and significant dormancy, such as many species of trees, are left largely unexplored. In this light, we conclude our review with ideas that we hope will encourage future research on both theoretical and experimental aspects of this important problem.

http://mcfns.com/index.php/Journal/article/view/6_26 2014/04/23 - 18:04

A general framework is proposed for the formulation and simulation of spatially explicit individual-based models of plant communities. A software implementation, siplab, was developed using the R statistical programming language. The scheme is a synthesis that encompasses many approaches from the literature, making possible to compare and combine their different components. Relationships between plant growth and various competition or assimilation indices are discussed, together with the choice of state variables and statistical issues in growth equations. Modelling is extended to deal with environmental heterogeneity, specified as a given resource distribution in the plane. Plants exert competitive pressure over resources at each point, represented by size- and distance-dependent functions that emulate or generalize similar concepts used in existing models. The partitioning of resources where these functions overlap is parametrized in a way that includes the one-sided fully asymmetric allocation of tessellation models, as well as a continuum of symmetric and asymmetric resource sharing alternatives. Finally, the plant resource uptake is integrated over space, with an optional size- and distance-dependent plant response or efficiency weighting. The framework and software permit conducting simulation studies where results are less dependent on any specific model structure.

http://mcfns.com/index.php/Journal/article/view/6_36 2014/04/23 - 18:04

A general framework is proposed for the formulation and simulation of spatially explicit individual-based models of plant communities. A software implementation, siplab, was developed using the R statistical programming language. The scheme is a synthesis that encompasses many approaches from the literature, making possible to compare and combine their different components. Relationships between plant growth and various competition or assimilation indices are discussed, together with the choice of state variables and statistical issues in growth equations. Modelling is extended to deal with environmental heterogeneity, specified as a given resource distribution in the plane. Plants exert competitive pressure over resources at each point, represented by size- and distance-dependent functions that emulate or generalize similar concepts used in existing models. The partitioning of resources where these functions overlap is parametrized in a way that includes the one-sided fully asymmetric allocation of tessellation models, as well as a continuum of symmetric and asymmetric resource sharing alternatives. Finally, the plant resource uptake is integrated over space, with an optional size- and distance-dependent plant response or efficiency weighting. The framework and software permit conducting simulation studies where results are less dependent on any specific model structure.

http://mcfns.com/index.php/Journal/article/view/MCFNS_6_36 2014/04/18 - 21:12

Fuel treatment is an important component of wildland fire management. This research revised and applied a mathematical programming model to schedule fuel treatment to fragment fuel patches with high fire intensity hazard. It differs from many previous fuel treatment scheduling models that aimed at detailed fire spread control. This new approach does not rely on the accurate prediction of future fire spread direction, speed and duration. Preliminary analyses suggested that scheduling fuel treatment to fragment high fire hazard fuel patches has similar effects as scheduling fuel treatment to control fires with very long fire duration. Both modeling strategies could effectively lower the risk of future fires with various spread directions, spread speeds and durations. Tests also suggested that fuel treatment layouts designed to control fires with short durations might not perform well when the actual fire duration is much longer that it is planned for. This research presented a new and practical approach in patch oriented fuel management.

http://mcfns.com/index.php/Journal/article/view/MCFNS_6_1 2014/04/04 - 17:10

Adjacency constraints along with harvest volume constraints are important in long term forest management planning. Simulated annealing (SA) has previously been successfully applied when addressing such constraints. The objective of this paper is to assess the performance of SA using three methods for generating candidate solutions. Biased probabilities in the management unit (MU) selection were introduced, one static and one dynamic. The rst one (Method 1) is the conventional (static) method. The two other methods were implemented through a search vector used in the candidate solution generator. These methods are based on (Method 2) the number of treatment schedules and standard deviation of NPV within MUs and (Method 3) the MU's potential improvement in the objective function value, the number of URM adjacency violations an MU is involved in, the period specic volume harvested in an MU and the number of times an MU is selected. The methods were tested on a large number of datasets including 300 hypothetical forest landscapes characterized by three dierent initial age class distributions, respectively young, normal and old. Evaluation of the methods was accomplished by means of objective function values and rst feasible iteration. Solutions improved when introducing bias in the probabilities for MU selection (Methods 2 and 3) compared to the conventional method (Method 1) and when the probability bias for selecting MUs is dynamic (Method 3) rather than static (Methods 1 and 2). The mean improvement for the average GAP obtained by Method 3 for young, normal and old forest landscapes was 20.88%, 12.84% and 5.20%, respectively. Whereas for the minimum GAP the mean improvement was 21.96%, 14.30% and 6.05% for young, normal and old forest landscapes, respectively.

http://mcfns.com/index.php/Journal/article/view/MCFNS_6_11 2014/04/04 - 17:10

When a plant living in an unpredictable environment produces seeds, its ideal strategy might not be to have all seeds germinate at once. What is the germination fraction that will maximize a plant's fitness, allowing the plant to hedge its bets in case of a poor year? To answer this question, in his now classic 1966 paper, Dan Cohen worked out the optimal annual germination fraction for seeds in a fluctuating environment. His result was elegant, but relied on a series of simplifying assumptions. We focus here on two specific assumptions. Namely, Cohen assumed that the population consists of annual plants, which have no adult age-structure, and that a seed's age has no effect on whether or not it will germinate. We review empirical and theoretical papers that have considered what happens when one or both of these assumptions is relaxed. More than a half-century has passed since Cohen's landmark study, and yet the existing literature has yet to provide theoretical solutions for perennial species as Cohen was able to do for annuals. Empirical studies have addressed short-lived perennials with minimal seed dormancy. However, perennials with longer lifespans and significant dormancy, such as many species of trees, are left largely unexplored. In this light, we conclude our review with ideas that we hope will encourage future research on both theoretical and experimental aspects of this important problem.

http://mcfns.com/index.php/Journal/article/view/MCFNS_6_26 2014/04/04 - 17:10

We present a collection of papers derived from the 2012 Forest Inventory and Analysis (FIA) Symposium held on December 4-6, 2012 in Baltimore, MD, USA. The symposium featured 128 oral presentations with nearly 200 attendees from the United States and other countries. A proceedings from the symposium included 75 papers as well as abstracts for all presentations and posters. The symposium theme, \textit{Moving from Status to Trends}, focused on the ability to perform trend or time series analysis using national forest inventory data. A wide range of topics were covered including forest products, social dimensions of forestry, landscape change, analytical tools, Landsat time series, forest carbon, and many others. Based on these presentations, we have assembled a selection of several papers that presented examples of trend analyses and projections using forest inventory data. This Special Issue contains four of these papers that passed the MCFNS double-blind peer-review by a minimum of three peers.

http://mcfns.com/index.php/Journal/article/view/MCFNS_175 2013/10/02 - 08:23

Prediction of soil organic carbon (SOC) at unsampled locations is central to statistical modeling of regional SOC stocks. This is often accomplished by applying geostatistical techniques to plot inventory data. However, in many cases inventory data is sparsely sampled (<0.1 plots/km^2) relative to the region of interest, and it is unknown if geostatistics provides any advantage. Our objective was to test whether modeling spatial autocorrelation, in multivariate and univariate predictive models, improved estimates of SOC at prediction locations based on sparsely-sampled inventory data. We conducted our study using a dataset sampled across all forested land in the Coastal Plain physiographic province of New Jersey, USA. We considered five models for predicting SOC, two linear regression models (intercept only and multiple regression with predictor variables), ordinary kriging (a univariate spatial approach), and two multivariate spatial methods (regression kriging and co-kriging). We conducted a simulation study in which we compared the predictive performance (in terms of root mean squared error) of all five models. Our results suggest that our sparsely-sampled SOC data exhibits no spatial structure (Moran’s I=0.05, p=0.39), though several of the covariates are spatially autocorrelated. Multiple linear regression had the best performance in the simulation study, while co-kriging performed the worst. Our results suggest that when inventory data is dispersed across the region of interest, modeling spatial autocorrelation does not provide significant advantage for predicting SOC at unsampled locations. However, it is unknown whether this autocorrelation does not exist at broad scales, or if sparse sampling strategies are unable to detect it. We conclude that in these situations, multiple regression provides a straightforward alternative to predicting SOC for mapping studies, but that more work on the spatial structure of soil carbon across multiple scales is needed.

http://mcfns.com/index.php/Journal/article/view/MCFNS_163 2013/10/02 - 08:23

The coarsened exact matching (CEM) method is used to match annual forest inventory plots awaiting remeasurement with plots that have already been remeasured. This results in a model-free approach for short term inventory projections. CEM has many desirable properties relative to other matching methods and is easy to apply within a SQL database. The combination of short term projections with a 3 or 5 year moving window is suggested for providing trend estimates that include the current year and a few years into the future. The default projection represents business as usual. A method to bias the plot matching to generate desired scenarios is also developed. These ideas and methods are demonstrated with several applications to forest inventory data. Scenarios are generated where increasing future harvest levels are stochastically controlled to demonstrate this capability with operational data.

http://mcfns.com/index.php/Journal/article/view/MCFNS_157 2013/10/02 - 08:23

Large-scale and long-term habitat management plans are needed to maintain the diversity of habitat classes required by wildlife species. Planning efforts would benefit from assessments of potential climate and land-use change effects on habitats. We assessed climate and land-use driven changes in areas of closed- and open-canopy forest across the Northeast and Midwest by 2060. Our assessments were made using projections based on A1B and A2 future scenarios developed by the Intergovernmental Panel on Climate Change. Presently, forest land covers 70.2 million ha and is evenly divided between closed- and open-canopy habitats. Projections indicated that total forest land would decrease by 3.8 or 4.5 million ha for A2 and A1B, respectively. Within persisting forest land, the balance between closed- and open-canopy habitats depended on assumed harvest rates of woody biomass. Standard harvest rates led to closed-canopy habitat attaining a slight majority of total forest land area. Intensive harvest rates resulted in the majority of forest land being in open-canopy habitat for A1B or maintained the even split between closed- and open-canopy habitats for A2. Ultimately, managers need to identify benchmark habitat conditions informed by historical conditions and wildlife population dynamics and plan to meet these benchmarks in dynamic forest landscapes.

http://mcfns.com/index.php/Journal/article/view/MCFNS_165 2013/10/02 - 08:23

Changing climate may pose a threat to forest tree species, forcing three potential population-level responses: toleration/adaptation, movement to suitable environmental conditions, or local extirpation. Assessments that prioritize and classify tree species for management and conservation activities in the face of climate change will need to incorporate estimates of the risk posed by climate change to each species. To assist in such assessments, we developed a set of four quantitative metrics of potential climate change pressure on forest tree species: (1) percent change in suitable area, (2) range stability over time, (3) range shift pressure, and (4) current realized niche occupancy. All four metrics are derived from climate change environmental suitability maps generated using the Multivariate Spatio-Temporal Clustering (MSTC) technique, which combines aspects of traditional geographical information systems and statistical clustering techniques. As part of the Forecasts of Climate-Associated Shifts in Tree Species (ForeCASTS) project, we calculated the predicted climate change pressure statistics for North American tree species using occurrence data from the USDA Forest Service Forest Inventory and Analysis (FIA) program. Of 172 modeled tree species, all but two were projected to decline in suitable area in the future under the Hadley B1 Global Circulation Model/scenario combination. Eastern species under Hadley B1 were predicted to experience a greater decline in suitable area and less range stability than western species, although predicted range shift did not differ between the regions. Eastern species were more likely than western species, on average, to be habitat generalists. Along with the consideration of important species life-history traits and of threats other than climate change, the metrics described here should be valuable for efforts to determine which species to target for monitoring efforts and conservation actions.

http://mcfns.com/index.php/Journal/article/view/MCFNS_169 2013/10/02 - 08:23

Acquiring preference information from decision-makers and stakeholders may carry biasing effects due to question framing. In order to avoid unwanted distortions, respondent-driven querying methods are advisable to apply; however, concerning multiple stakeholders a challenge remains how to combine individually collected concepts and further on their individual valuations to an unified preference information. This paper introduces one solution: a semi-automatic stochastic simulation of joint preferences from partially overlapping individual concept lists and preference ratings. We used completed expert interview dataset of cultural sustainability indicators acquired for comparing bioenergy production chains. According to the results the approach seems generally applicable, but the feasibility may vary according to case characteristics. Combining concept list valuations with stochastic simulations may be more feasible the more similar the expected concept structures are. The presented method contributes particularly to planning processes in which democratic participation of a large number of stakeholders is needed in the goal setting phase. However, more tests with different decision problem types are needed to verify and refine the present findings.

http://mcfns.com/index.php/Journal/article/view/138 2013/04/02 - 18:25

This is an introduction of the initial publication of the new Special Section of the MCFNS journal on micro-detail detection and tracking problems and various related interdisciplinary studies in other disciplines, which are deemed to be synergistic or relevant to detection and tracking problems.  The initial selection of publications presented here arose from the Smolensk Conference held on Oct. 22, 2012, in Warsaw, Poland.  This Special Section originated out of a collaboration between the MCFNS editors and the organizers of the Smolensk Conference, but the submissions of the presented here manuscripts was independent from this organization; all authors submitted their manuscripts independently of each other.  This issue contains four of the papers presented at the conference.  In what follows, I briefly review the background behind the creation of this Special Section series and introduce the papers contained herein.

http://mcfns.com/index.php/Journal/article/view/164 2013/04/02 - 18:25

This study presents comparative analysis of high-resolution satellite imagery taken on different dates around a detected incident of interest.  Under an assumption of a micro-detail land monitoring and disturbance detection interests we compared the patterns of image captured disturbances on the analyzed site and leveraged their interpretation with knowledge base published on relevant subjects.  The incident of interest was the Polish Air Force One TU-154M plane destruction on Apr. 10, 2010.  We analyzed the image changes on micro-detail level tracked over time and considered with respect to the patterns of destruction and the plane debris size distribution in space against a broad engineering literature describing destruction patterns of thin walled structures, such as planes and cars.  Then, we compared the spatial distribution of the debris between the pictures taken on different dates.  Finally, we also considered on ground changes in soil moisture and landscape features between different images. The main conclusions from the study were that: (i) the pattern of the plane destruction debris and their spatial distribution found on the ground following the catastrophe was not consistent with expectations associated with a plane crash but rather was suggestive of a plane explosion; (ii) the scene and the plane debris were manipulated over time during the very initial period after the destruction; (iii) surprisingly the numerous heavy equipment vehicles present on the site , which were much larger than the image spatial resolution, were not recorded on any of the satellite images from Apr. 11, 12, or 14, 2010;  (iv) the frequency of the high resolution satellite imagery captured around this airport on the dates of Apr. 5, 9, 11, 12, and 14, 2010, is intriguing given that the last captured image of this type prior to April 5, 2010, took place only in 2007; and (v) a large amount of snow-like high reflectivity coverage in the middle of the crash scene was followed by low reflectivity (suggestive of dry ground) areas following the crash despite generally swampy surroundings of the site and no reported explosion of the plane, which could imply a fast drying out of the melting snow large amounts of water.

http://mcfns.com/index.php/Journal/article/view/154 2013/04/02 - 18:25

This is a collection of reports that consists of three parts. The author is a Professor of PowerElectrical Engineering, so he focuses on the Tu-154M power electric system and all aspects of the air crashthat relate to electrical equipment and wiring.Part I discusses the electric power system of the Tu-154M. After brief introduction to aircraft power systems,the results of reverse design and analysis of GT40PCh6 wound-eld synchronous generator including shortcircuit have been presented. An example of failure of GT40PCh6 generator is the re of the Tu-154B-2 onJanuary 1, 2011 before taking o at Surgut airport (ight 7K348). Guidelines for proper investigation ofaircraft electric equipment and wiring after crash have been given. There is no evidence of examinationof most electrical equipment of the Tu-154M No 101 after crash on April 10, 2010. It is now extremelydicult to determine, if the electric power system of the Tu-154M No 101 was operating correctly in thelast seconds of the ight, or not.Part II analyzes the fuel system and possibility of explosion of fuel-air mixture as a result of arcing and/orstatic electricity in the left wing outer fuel tank of the Tu-154M No 101. Examples of explosions of fueltanks (Boeing 747-131 TWA 800 on June 17, 1996 and Boeing 727-200 at Bangalore Airport on May 42006) have been discussed. Although probability of explosion of fuel in the left wing outer tank due theelectric short circuit, arcing or static electricity is low, this problem should be carefully considered in futureexamination of the wreckage and remaining electrical wiring and equipment.Part III describes a comparative analysis of hypothetical collision of the Tu-154M No 101 with birch tree,full-scale dynamic crash test of Douglas DC-7 and full-scale dynamic crash test of Lockheed Constellation1649. The analysis pertains to the technical data of the Tu-154M, DC-7 and LC-1649 airliners, dierencesin their construction and conditions of collision/impact.

http://mcfns.com/index.php/Journal/article/view/147 2013/04/02 - 18:25

This paper demonstrates application of a numerical methodology for full scale aircraft impact crashworthiness investigation. A special case, impact of an aircraft wing with a tree, was studied using LS-DYNA and ANSYS CFX. In particular, a detailed finite element model of the wing structure was represented as a box structure containing skin, spars and ribs, and fuel was represented as distributed mass. Several material models were utilized and verified using leading-edge bird strike and wood bending experiments. Wood model Mat 143 with material parameters developed based on the wood bending test was found as the most accurate in comparison with the experiment. The aerodynamic pressure distribution on the overall surface of the wing was accomplished using the commercially available Computational Fluid Dynamics (CFD) software ANSYS CFX. Results of the aerodynamic pressures on the wings surfaces were imported into the LS-DYNA finite element model. Parametric studies showed that a fragment of the leading edge of the wing was destroyed by the tree but the lifting surface of the wing was not destroyed. In every simulation scenario, the tree was cut by the first spar of the wing and fell in the direction of the movement of the airplane.

http://mcfns.com/index.php/Journal/article/view/153 2013/04/02 - 18:25

We estimated wood quality parameters for a specific tree trunk using samples of this tree’s branch, and auxiliary samples from other similar species, based on analysis of wood density, modulus of elasticity (MOE), and microfibril angle (MFA), measured with the near-infrared spectroscopy (NIRS) and SilviScan processes.  The measured materials included a branch sample from the subject tree, also known as the smolensk birch1, and stem analysis disk samples from silver birch (Betula pendula Roth) trees collected in central Poland.  We analyzed and modeled the pith-to-bark and base-to-tip density changes in the silver birch samples, and using developed models estimated the subject tree trunk air-dry wood quality parameters and compared them with published yellow birch (Betula alleghaniensis) and silver birch tabular data.  Then we compared the corresponding surrogated green wood parameters of the subject tree against the standard American utility wood pole parameters, and identified environmental adjustments necessary for a realistic and accurate representation of the final subject tree wood characteristics.  The final conclusions from this study are that the subject tree dry wood parameters are not significantly different (in the statistical sense) from the well-documented yellow birch parameters, which were used as their surrogate, and even without the due reductions in parameters for excessive amount of whorls and branches, and for the height of the tree brake (5 to 7 m above ground), the structural parameters of the subject tree green wood, as applicable to live tree and as surrogated by appropriate yellow birch parameters, are generally weaker than corresponding dry wood parameters for the standard American wood poles and weaker then the southern yellow pine parameters. The adjustments for the whorls and knots and height of the brake may yield some additional 50% reduction in the estimates for the subject tree structural wood parameter values.

http://mcfns.com/index.php/Journal/article/view/155 2013/04/02 - 18:25

Previous studies suggest that management intensity zoning systems,  such as the triad approach, could allow Canada's forest industry to  maintain or increase timber harvest levels while simultaneously  reducing its environmental impact.  In most such studies, the zones  are exogenously specified.  In this study, we use a linear  programming model to endogenously allocate forest land to management  intensity zones given several alternative policy scenario  formulations.  We examine how alternative policy scenarios affect  the net present value of the optimal forest management plan, timber  output, and the spatial allocation of land to management intensity  zones. We conclude that policies which facilitate optimal zoning  could enable land use specialization to increase both profits and  ecological protection.  Such zoning, however, can only happen if  provincial governments in Canada revise their forest policies with  respect to allocation of forest tenures and establishment of exotic  plantations on public forest land.

http://mcfns.com/index.php/Journal/article/view/135 2012/10/02 - 02:17

The principles behind self-thinning laws and stand density management diagrams are examined. Relationships are analyzed based on trajectories of unthinned and thinned stands in a 3-dimensional state space. Limiting self-thinning lines and planes are demonstrated using a dynamic stand growth model for loblolly pine.

http://mcfns.com/index.php/Journal/article/view/144 2012/10/02 - 02:16

The traditional coefficient of determination or R-square is the proportion of variation explained by a regression model versus the variation explained by the mean. This measure does not discriminate well between alternative self-referencing models such as site index curves. A generalized R-square based on the proportion of the variation explained by the self-referencing model versus the variation explained by a straight line through zero for each growth series provides better discrimination between candidate models. Three growth series from the South Africa Correlated Curve Trend Study are used to illustrate the difference between the traditional R-square and the generalized R-square.

http://mcfns.com/index.php/Journal/article/view/142 2012/10/02 - 02:16

Because different tree parameters are of differing importance, and have different variability, efficiency in sampling would suggest that some of the principle variables be subsampled. One convenient way to do this is to sample different numbers of items at the same sample locations. This paper is a review of some current techniques in subsampling for measured values, especially with Variable Plot sampling, but including Fixed Plot and 3P sampling as well.

http://mcfns.com/index.php/Journal/article/view/143 2012/10/02 - 02:16

Static horizontal position accuracy of a consumer-grade GPS receiver was estimated in a young loblolly pine (Pinus taeda) plantation in Georgia (USA) to determine whether the arrangement of trees had any influence on position quality. No significant relationship was observed between static horizontal positional accuracy and environmental variables (air temperature, relative humidity, and atmospheric pressure) or the planned positional dilution of precision (PDOP) of the NAVSTAR satellite configuration. However, in a semi-spatial sense, we found moderate correlation between average positional error and a few forest structure measures. For example, we observed that as hardwood (deciduous species) basal area and hardwood tree count within 4 or 5 m of a test point increased, the average positional error tended to increase. No significant correlation was observed using forest structure values obtained within 3 m of each test point. However, some directional effects were observed with increases of pine tree count, pine basal area, and total live tree basal area within 4 or 5 m of each test point. And using rose diagrams (circular histograms), we observed that in some sense there was a negative attraction between the location of live trees and the position determined by the GPS receiver.

http://mcfns.com/index.php/Journal/article/view/140 2012/10/02 - 02:16

Optimal parameter settings to improve the efficiency of solving harvest scheduling models with adjacency constraints were examined using Ilog’s Cplex® 11.2 optimizer tuning tool.  A total of 160 randomly generated hypothetical forests were created with either 50 or 100 stands and four age-class distributions.  Mixed integer programming problems were formulated in Model I form with four different adjacency constraint types, two Unit Restriction Model (URM) adjacency constraints (Pairwise and Maximal Clique) and two Area Restriction Model (ARM) formulations (Path and Generalized Management Unit).  A total of 640 problem sets―where a set is a common forest size, age-class distribution, and adjacency constraint type―were tuned to determine optimal parameter settings and then were solved at both the default and optimal settings.  In general, mean solution time was less for a given problem set using the optimal parameters compared to the default parameters.  The results discussed provide a simple approach to decrease the solution time of solving mixed integer forest planning problems with adjacency constraints.

http://mcfns.com/index.php/Journal/article/view/105 2012/03/08 - 01:26

Spatially-explicit harvest scheduling models optimize the spatiotemporal layout of forest management actions to best meet management objectives such as profit maximization, even flow of products, or wildlife habitat preservation while satisfying a variety of constraints. This investigation focuses on modeling maximum harvest opening size restrictions whose role is to limit the size of contiguous clear cuts on a forested landscape. These restrictions, a.k.a. green-up constraints, allow adjacent forest stands to be cut within a pre-specified timeframe, called green-up period, only if their combined area does not exceed a limit. We present a strengthening procedure for one of the existing integer programming formulations of this so-called Area Restriction Model and test the computational performance of the new model on sixty hypothetical and five real forest planning applications. The results suggest that the strengthened model can often outperform the other three existing formulations.

http://mcfns.com/index.php/Journal/article/view/110 2012/03/08 - 01:26

This study of tree morphology is presented in three parts. Part 1 deals with the over-all shape of trees (their profiles). A mathematical model based on the distribution of leaves shows that all profiles, from rounded to conical, is determined by one parameter. Part 2 deals with the angle of branching. Field measurements show that the sum of the areas of stems exiting a fork is usually greater than the area of the stem entering the fork. Mathematical analysis shows that this “bulking up” actually reduces the quantity of plant tissue incorporated in the branching. Furthermore, the angle of branching increases with the degree of bulking up. Part 3 brings together the concepts of the first two parts: here, the cross-sectional area of the trunk as a function of position along the trunk is determined by the profile of the tree and the angle of side branching off the trunk. From field observation, the profile of a tree (i.e., the outline of its crown) has two prominent characteristics: (i) azimuthal symmetry about the central axis (often the main stem or trunk), as evidenced both in foliage and scaffolding; and (ii) decrease in leaf density from branch-end toward the central axis. From these two conditions (including a presumed radial distribution of leaves) a mathematical model is developed using the calculus of variations that predicts the profile The results of this analysis are consistent with the general observation that profiles range from the nearly spherical in the case of uniform distribution of leaves throughout the crown, to essentially conical when the leaves are found largely on the branch-ends. The results are presented in figures showing theoretical profiles overlaid on photographs of representative trees. Part 2 is based on field measurements that show that the cross-sectional area of a branch (or stem) entering a fork (in the direction of water transport) is less than the sum of the cross-sectional areas of the branches leaving that fork. Again, using the calculus of variations, it is shown that the angle of branching can be related to this “bulking up”. Field measurements are in general agreement with this prediction. Part 3 provides a separate test of the validity of the concepts introduced in the first two Parts. Using equations appropriate to a tree with a single main stem and horizontal side branches, the crosssectional area of the trunk is calculated as a function of position on the trunk. The results are compared with field measurements.

http://mcfns.com/index.php/Journal/article/view/MCFNS.4%3A2 2012/03/02 - 09:31

Optimal parameter settings to improve the efficiency of solving harvest scheduling models with adjacency constraints were examined using Ilog’s Cplex® 11.2 optimizer tuning tool.  A total of 160 randomly generated hypothetical forests were created with either 50 or 100 stands and four age-class distributions.  Mixed integer programming problems were formulated in Model I form with four different adjacency constraint types, two Unit Restriction Model (URM) adjacency constraints (Pairwise and Maximal Clique) and two Area Restriction Model (ARM) formulations (Path and Generalized Management Unit).  A total of 640 problem sets―where a set is a common forest size, age-class distribution, and adjacency constraint type―were tuned to determine optimal parameter settings and then were solved at both the default and optimal settings.  In general, mean solution time was less for a given problem set using the optimal parameters compared to the default parameters.  The results discussed provide a simple approach to decrease the solution time of solving mixed integer forest planning problems with adjacency constraints.

http://mcfns.com/index.php/Journal/article/view/MCFNS.4%3A16 2012/03/02 - 09:31

Spatially-explicit harvest scheduling models optimize the spatiotemporal layout of forest management actions to best meet management objectives such as profit maximization, even flow of products, or wildlife habitat preservation while satisfying a variety of constraints. This investigation focuses on modeling maximum harvest opening size restrictions whose role is to limit the size of contiguous clear cuts on a forested landscape. These restrictions, a.k.a. green-up constraints, allow adjacent forest stands to be cut within a pre-specified timeframe, called green-up period, only if their combined area does not exceed a limit. We present a strengthening procedure for one of the existing integer programming formulations of this so-called Area Restriction Model and test the computational performance of the new model on sixty hypothetical and five real forest planning applications. The results suggest that the strengthened model can often outperform the other three existing formulations.

http://mcfns.com/index.php/Journal/article/view/MCFNS.4%3A27 2012/03/02 - 09:31

Non-parametric k nearest neighbours (k-nn) techniques are increasingly used in forestry problems, especially in remote sensing. Parametric regression analysis has the advantage of well-known statistical theory behind it, whereas the statistical properties of k-nn are less studied. In this study, we compared the relative performance of k-nn and linear regression in an experiment. We examined the effect of three different properties of the data and problem: 1) the effect of increasing non-linearity, 2) the effect of balance of the modelling and test data and 3) the effect of the correct assumptions of the model form. In order to be able to determine the effect of these three aspects, we used simulated data and simple modelling problems. K-nn and linear regression gave fairly similar results with respect to the average RMSEs. In both cases, balanced modelling dataset gave better results than unbalanced dataset. When the results were examined within diameter classes, the k-nn results were less biased than regression model results, especially with extreme values of diameter. The differences increased with increasing non-linearity of the model and increasing unbalance of the data. The difference between the methods was more obvious, when the assumed model form was not exactly correct. This result, however, requires that the modelling and test datasets have a similar distribution: if the distributions are different, regression model may be more robust than k-nn. Keywords: modelling, regression, imputation, balance of data

http://mcfns.com/index.php/Journal/article/view/MCFNS.4%3A50 2012/03/02 - 09:31

Non-parametric k nearest neighbours (k-nn) techniques are increasingly used in forestry problems, especially in remote sensing. Parametric regression analysis has the advantage of well-known statistical theory behind it, whereas the statistical properties of k-nn are less studied. In this study, we compared the relative performance of k-nn and linear regression in an experiment. We examined the effect of three different properties of the data and problem: 1) the effect of increasing non-linearity, 2) the effect of balance of the modelling and test data and 3) the effect of the correct assumptions of the model form. In order to be able to determine the effect of these three aspects, we used simulated data and simple modelling problems. K-nn and linear regression gave fairly similar results with respect to the average RMSEs. In both cases, balanced modelling dataset gave better results than unbalanced dataset. When the results were examined within diameter classes, the k-nn results were less biased than regression model results, especially with extreme values of diameter. The differences increased with increasing non-linearity of the model and increasing unbalance of the data. The difference between the methods was more obvious, when the assumed model form was not exactly correct. This result, however, requires that the modelling and test datasets have a similar distribution: if the distributions are different, regression model may be more robust than k-nn. Keywords: modelling, regression, imputation, balance of data

http://mcfns.com/index.php/Journal/article/view/MCFNS.4-51 2012/03/01 - 11:37

This study of tree morphology is presented in three parts. Part 1 deals with the over-all shape of trees (their profiles). A mathematical model based on the distribution of leaves shows that all profiles, from rounded to conical, is determined by one parameter. Part 2 deals with the angle of branching. Field measurements show that the sum of the areas of stems exiting a fork is usually greater than the area of the stem entering the fork. Mathematical analysis shows that this “bulking up” actually reduces the quantity of plant tissue incorporated in the branching. Furthermore, the angle of branching increases with the degree of bulking up. Part 3 brings together the concepts of the first two parts: here, the cross-sectional area of the trunk as a function of position along the trunk is determined by the profile of the tree and the angle of side branching off the trunk. From field observation, the profile of a tree (i.e., the outline of its crown) has two prominent characteristics: (i) azimuthal symmetry about the central axis (often the main stem or trunk), as evidenced both in foliage and scaffolding; and (ii) decrease in leaf density from branch-end toward the central axis. From these two conditions (including a presumed radial distribution of leaves) a mathematical model is developed using the calculus of variations that predicts the profile The results of this analysis are consistent with the general observation that profiles range from the nearly spherical in the case of uniform distribution of leaves throughout the crown, to essentially conical when the leaves are found largely on the branch-ends. The results are presented in figures showing theoretical profiles overlaid on photographs of representative trees. Part 2 is based on field measurements that show that the cross-sectional area of a branch (or stem) entering a fork (in the direction of water transport) is less than the sum of the cross-sectional areas of the branches leaving that fork. Again, using the calculus of variations, it is shown that the angle of branching can be related to this “bulking up”. Field measurements are in general agreement with this prediction. Part 3 provides a separate test of the validity of the concepts introduced in the first two Parts. Using equations appropriate to a tree with a single main stem and horizontal side branches, the crosssectional area of the trunk is calculated as a function of position on the trunk. The results are compared with field measurements.

http://mcfns.com/index.php/Journal/article/view/MCFNS.4-2 2012/02/29 - 11:07

This study of tree morphology is presented in three parts. Part 1 deals with the over-all shape of trees (their profiles). A mathematical model based on the distribution of leaves shows that all profiles, from rounded to conical, is determined by one parameter. Part 2 deals with the angle of branching. Field measurements show that the sum of the areas of stems exiting a fork is usually greater than the area of the stem entering the fork. Mathematical analysis shows that this “bulking up” actually reduces the quantity of plant tissue incorporated in the branching. Furthermore, the angle of branching increases with the degree of bulking up. Part 3 brings together the concepts of the first two parts: here, the cross-sectional area of the trunk as a function of position along the trunk is determined by the profile of the tree and the angle of side branching off the trunk. From field observation, the profile of a tree (i.e., the outline of its crown) has two prominent characteristics: (i) azimuthal symmetry about the central axis (often the main stem or trunk), as evidenced both in foliage and scaffolding; and (ii) decrease in leaf density from branch-end toward the central axis. From these two conditions (including a presumed radial distribution of leaves) a mathematical model is developed using the calculus of variations that predicts the profile The results of this analysis are consistent with the general observation that profiles range from the nearly spherical in the case of uniform distribution of leaves throughout the crown, to essentially conical when the leaves are found largely on the branch-ends. The results are presented in figures showing theoretical profiles overlaid on photographs of representative trees. Part 2 is based on field measurements that show that the cross-sectional area of a branch (or stem) entering a fork (in the direction of water transport) is less than the sum of the cross-sectional areas of the branches leaving that fork. Again, using the calculus of variations, it is shown that the angle of branching can be related to this “bulking up”. Field measurements are in general agreement with this prediction. Part 3 provides a separate test of the validity of the concepts introduced in the first two Parts. Using equations appropriate to a tree with a single main stem and horizontal side branches, the crosssectional area of the trunk is calculated as a function of position on the trunk. The results are compared with field measurements.

http://mcfns.com/index.php/Journal/article/view/MCFNS.4-2 2012/02/29 - 11:07