Footprint Geometry Research Articles

Examining the Effectiveness of Aerial Firefighting with the Components of Firebreak Requirements and Footprint Geometry—Critics of the Present Practice

The negative impact of climate change is increasingly evident in the severity of forest fires. Fires are becoming more intense and can often only be controlled by aerial means. Aerial firefighting is known as a very effective method—in some cases, it is the only option—of suppressing fire, but it is a very expensive solution. Recently, the effectiveness of this method has received a lot of criticism, with some studies showing a loss of between 60 and 95%, so it is worth approaching this issue in a different way. The aim of this study is to estimate losses using a new method that has not been used before. For this purpose, this study focuses on two components: the requirements of the firebreak and the geometry of the footprint. For the first, the rules of thumb of the practice were applied depending on the fireline intensity. One is the required coverage level of the surface with suppressant, and the other is the required wetted bandwidth, which is the firebreak. In practice, the firebreak should be 2–2.5 times wider than the length of the flame. For the footprint geometry, the author used the results of previous studies dealing with footprint formation. At the end, the design of the required firebreak and the simplified design of the footprint, which is an ellipsoid, were compared to each other. The results show that, in the case of a fireline intensity of 3 MWm−1 and a coverage level of 2.4 kgm−2, the loss is approximately 36.4–44.6% for the ellipsoidal footprint alone and 86–87.8% for the total amount of extinguishing agent. The conclusion is that future work should focus not on a more accurate description and understanding of emissions but on developing a technology that can change the shape of the footprint from an elliptical to a rectangular shape.

AUTOMATIC BUILDING FOOTPRINT EXTRACTION FROM 3D LASERSCANS

Abstract. Building footprints are a prerequisite for many tasks such as urban mapping and planning. Such structures are mostly derived using airborne laser scanning which reveals rather roof structures than the underlying hidden footprint boundary. This paper introduces an approach to extract a 2D building boundary from a 3D point cloud stemming from either terrestrial scanning or via close-range sensing using a mobile platform, e.g. drone. To this end, a pipeline of methods including non-parametric kernel density estimation (KDE) of an underlying probability density function, a solution of the Travelling Salesperson Problem (TSP), outlier elimination and line segmentation are presented to extract the underlying building footprint. KDE turns out to be suitable to automatically determine a horizontal cut in the point cloud. An ordering of the resulting points in this cut using a shortest possible tour based on TSP allows for the application of existing line segmentation algorithms, otherwise dedicated to indoor segmentation. Outliers in the resulting segments are removed using Density-Based Spatial Clustering of Applications with Noise (DBSCAN). The segments are then generalized leading to the final footprint geometry. We applied our approach on real-world examples and achieved an IoU between 0.930 and 0.998 assessed by ground truth footprints from both authoritative and volunteered geographic information (VGI) data.

Comparative Study on Matching Methods for the Distinction of Building Modifications and Replacements Based on Multi-Temporal Building Footprint Data

We compare different matching methods for distinguishing building modifications from replacements based on multi-temporal building footprint geometries from 3D city models. Manually referenced footprints of building changes were used to determine which thresholds are suitable for distinction. In addition, since the underlying LoD1 (Level of Detail 1) data is highly accurate, randomly generated position deviations were added to allow for transferability to less well-matched data. In order to generate a defined position deviation, a novel method was developed. This allows determination of the effects of position deviations on accuracy. Determination of these methods’ suitability for manipulation of data from sources of different levels of generalization (cross-scale matching) is therefore not the focus of this work. In detail, the methods of ‘Common Area Ratio’, ‘Common Boundary Ratio’, ‘Hausdorff Distance’ and ‘PoLiS’ (Polygon and Line Segment based metric) were compared. In addition, we developed an extended line-based procedure, which we called ‘Intersection Boundary Ratio’. This method was shown to be more robust than the previous matching methods for small position deviations. Furthermore, we addressed the question of whether a minimum function at PoLiS and Hausdorff distance is more suitable to distinguish between modification and replacement.

Building Function Mapping Using Multisource Geospatial Big Data: A Case Study in Shenzhen, China

Building function labelling plays an important role in understanding human activities inside buildings. This study develops a method of function label classification using integrated features derived from remote sensing and crowdsensing data with an extreme gradient boosting tree (XGBoost). The classification framework is verified based on a dataset from Shenzhen, China. An extended label system for six building types (residential, commercial, office, industrial, public facilities, and others) was applied, and various social functions were considered. The overall classification accuracies were 88.15% (kappa index = 0.72) and 85.56% (kappa index = 0.69). The importance of features was evaluated using the occurrence frequency of features at decision nodes. In the six-category classification system, the basic building attributes (22.99%) and POIs (46.74%) contributed most to the classification process; moreover, the building footprint (7.40%) and distance to roads (11.76%) also made notable contributions. The result shows that it is feasible to extract building environments from POI labels and building footprint geometry with a dimensional reduction model using an autoencoder. Additionally, crowdsensing data (e.g., POI and distance to roads) will become increasingly important as classification tasks become more complicated and the importance of basic building attributes declines.

Impact of draw velocity profile on footprint definition for primary rock

In block/panel caving mines the footprint geometry and the undercut level height are key planning elements that have a bearing on the project final value. Selection of these parameters obviously depends on the economic objective, but it is also strongly influenced by rock mass characteristics that define column extraction capacity from draw points. This paper presents a simple methodology that allows defining the footprint and the best height of draw (BHOD) based on column extraction velocities, which are defined with the aim of controlling mass rock dynamic response while caving is propagated. The proposed methodology can be used by industry because of the ease of application. A study case is presented for a block model which is evaluated by both the proposed methodology and nominal profit estimation.

List of abstracts

. Results obtained in the analysis of single layer and multilayered carbon stacks produced by PLD at low temperature will be presented. The mechanical properties of carbon single layers deposited at various laser pulse fluences, like hardness and elasticity, were determined by means of nano indentation measurements. It will be shown that a wide variety of mechanical properties can easily be adjusted by adapting the process parameters.

Paper #15 - Quantitative Anatomic Analysis of the Medial Ulnar Collateral Ligament Complex of the Elbow with Implications for Reconstructive Surgery

Background: As the rate of medial elbow reconstructive surgery continues to rise, a detailed assessment of the anatomy of the entire medial ulnar collateral ligament complex (MUCLC) is desired. Accordingly, the purposes of this study were to provide a robust anatomic digitization of the entire MUCLC complex (anterior bundle [AB], posterior bundle [PB], and transverse ligament [TL]) to determine the: areas, footprint geometries, distances to key bony landmarks, and isometry of all ligaments.

3D brush model to predict longitudinal tyre characteristics

ABSTRACTA 3D tyre brush model, which aims to predict the longitudinal tyre characteristic under steady-state conditions by modelling the occurring physical effects in the tyre–road contact patch, is presented. The model includes an analytical method to describe the tyre footprint geometry, the pressure distribution, the slip due to the lateral tyre contour, the slip due to braking or traction and the longitudinal as well as the lateral shear stresses on a flattened tyre. The presented development tool offers a method to investigate different rubber friction data (caused by different tread compounds and/or surface textures) and to analyse its influence on longitudinal tyre characteristics. The tyre design is fixed (same casing, dimension and pattern). The results include the shear stresses as well as the different sliding velocities in the contact patch for different slip conditions. The model was developed for a standard summer pattern design and a standard tyre dimension (205/55R16). It can also be adapted to other tread designs and tyre dimensions. To offer a good comparability between model results and test bench measurements, the surface curvature of an internal test rig is considered.

A Shadow-Overlapping Algorithm for Estimating Building Heights From VHR Satellite Images

Building height is a key geometric attribute for generating 3-D building models. We propose a novel four-stage approach for automated estimation of building heights from their shadows in very high resolution (VHR) multispectral images. First, a building’s actual shadow regions are detected by applying ratio-band algorithm to the VHR image. Second, 2-D building footprint geometries are identified using graph theory and morphological fuzzy processing techniques. Third, artificial shadow regions are simulated using the identified building footprint and solar information in the image metadata at predefined height increments. Finally, the difference between the actual and simulated shadow regions at every height increment is computed using Jaccard similarity coefficient. The estimated building height corresponds to the height of the simulated shadow region that resulted in the maximum value for Jaccard index. The algorithm is tested on seven urban sites in Cardiff, U.K. with various levels of morphological complexity. Our method outperforms the past attempts, and the mean error is reduced by at least 21%.

Footprint geometry and sessile drop resonance.

In this work, we examine experimentally the resonance of a sessile drop with a square footprint (square drop) on a flat plate. Two families of modal behaviors are reported. One family is identified with the modes of sessile drops with circular footprints (circular drop), denoted as "spherical modes." The other family is associated with Faraday waves on a square liquid bath (square Faraday waves), denoted as "grid modes." The two families are distinguished based on their dispersion behaviors. By comparing the occurrence of the modes, we recognize spherical modes as the characteristic of sessile drops, and grid modes as the constrained response. Within a broader context, we further discuss the resonance modes of circular sessile drops and free spherical drops, and we recognize various modal behaviors as surface waves under different extents of constraint. From these, we conclude that sessile drops resonate according to how wave-number selection by footprint geometry and capillarity compete. For square drops, a dominant effect of footprint constraint leads to grid modes; otherwise, the drops exhibit spherical modes, the characteristic of sessile drops on flat plates.

Modeling incision profile in AWJM of Titanium alloys Ti6Al4V

Abrasive water jet milling (AWJM) is a new way to perform controlled depth milling especially for hard materials, but it’s not yet enough reliable because of large variety of process parameters and complex footprint geometries that are not well mastered. In order to master the milling device in AWJM, a deep study on the footprint of a single path of the cutting head should first be considered. The flow of the AWJ and the distribution of abrasive particles coming out of the jet are related to the profile measured on the footprint. In this study, experiments were made on titanium alloys specimen to compare several theoretical models to the measured profile of the footprint. This study establishes new models to fit the incision profile taking in consideration the behavior of the abrasive particles impacting the workpiece.

Development of a real-time hybrid testing method in a centrifuge

This paper presents a pioneering real-time hybrid testing method for geotechnical centrifuges. The method was used to investigate the behaviour of a jack-up leg reinstalled near an existing footprint, a problem that is highly non-linear, stress dependent and involves complex soil–structure interactions. By physically modelling only the footprint–leg interaction and numerically modelling the rest of the jack-up structure, the method enables a realistic account of all the parameters involved in the interaction, including the footprint geometry, soil heterogeneity and structural properties of the jack-up unit. The paper also details the three-degree-of-freedom actuators developed to model the interaction, which features controlled loads and motions along the vertical, horizontal and moment directions, and the real-time algorithm that bridges the physical and numerical models. The algorithm allows the stiffness on each axis to be varied. Testing performed at 1g and in the centrifuge, modelling jack-ups with different stiffness on the horizontal and moment axes, is presented to validate the apparatus and methodology. The hybrid apparatus and real-time testing method were found to produce much more realistic boundary constraints than previous fixed-system apparatuses, and this allowed the test results to be considerably more informative, accurate and useful.

Technology Focus: Offshore Drilling and Completion (April 2015)

Technology Focus To the casual observer of completions and hydraulic fracturing, it might appear that multifractured horizontal wells are a relatively recent concept that materialized just as we required them for unconventionals. However, those in the know will recognize that the marriage of fracturing and stimulation operations with horizontals was forged almost 30 years ago in an environment far removed from unconventionals. In fact, it was the high-cost, limited-well, offshore environment that drove the need for higher production rates from single wellbores and indeed from horizontals and high-angle wells because of the limitations imposed by platform footprint and achievable step-out geometry. Substantial progress in multifractured horizontal wells was made in the 1990s by operators such as Maersk on the Dan field and BP on the Valhall field, in addition to onshore experiences with various operators such as UPRC in the Austin chalk and Arco in Alaska (the North Slope operational reality being effectively similar to offshore). Therefore, it is with great satisfaction that this month’s technical section includes papers demonstrating technologies from unconventionals that are beginning to be used to develop these offshore opportunities further. This month’s selections highlight a number of such applications, including open hole and cased hole, ball-drop actuated, and proppant plug staging. Most of the tools and approaches developed (onshore) for high efficiency in low-permeability propped fracturing are not currently wholly applicable to higher-permeability (offshore) environments because they typically depend on overdisplacement by design. However, these technologies are a fast-moving target, with highly cost- and time- efficient coiled-tubing (CT) underdisplacement techniques emerging now across unconventional plays. This means that we should see articles here very soon on these CT-deployed propped-fracturing approaches as they move offshore. As these innovations gain widespread acceptance, I would expect that the application of offshore fracturing will become a more attractive proposition once again. However, in all cases, the most critical aspects to achieving success will be that the technologies selected not only be fit-for-purpose but also reflect the formation quality and completion philosophy, rather than trying to fit square pegs into round holes. JPT Recommended additional reading at OnePetro: www.onepetro.org. SPE 170773 Flushing Away the Profit: The Potential Misapplication of Unconventional Fracturing Technology on a Global Scale by M. Rylance, BP, et al. OTC 24179 Drilling and Completing Cascade and Chinook Wells: A Design and Execution Case History by Flavio Dias De Moraes, Petrobras, et al. OTC 25321 Ultrahigh-Strength Proppant Developed for Deep, Offshore Completions by Terry Palisch, Carbo Ceramics, et al.

Geometric characterisation and out-of-plane seismic stability of low-rise unreinforced brick masonry buildings in Auckland, New Zealand

The 2010-2011 Canterbury earthquakes and corresponding Royal Commission reports have resulted in changes to the legislative environment and led to increased public awareness in New Zealand of the earthquake performance of unreinforced masonry (URM) buildings. As a result, building regulators, owners, tenants, users and heritage stakeholders will be facing a unique challenge in the near future where assessments, improvements and demolitions of URM buildings are expected to occur at an unusually high rate. Auckland is the largest city in New Zealand and because of the relative prosperity of Auckland during the period 1880-1935 when most URM buildings were being constructed in New Zealand, the city has the largest number of URM buildings in the country. Identifying those buildings most at seismic risk in Auckland’s large and varied building stock has warranted a rapid field assessment program supplemented by strategically chosen detailed assessments. Information that can be procured through rapid field inspections includes the building geometric typologies (e.g., heights, building footprint geometry and isolated versus row configuration), elevation type (e.g., perforated frame versus solid wall), wall construction (e.g., solid versus cavity, number of leaves) and basic construction material type (e.g., clay brick versus stone). Furthermore, investigation into the architectural history, heritage status and functional usage of Auckland’s URM buildings will affect the direction of retrofit strategies and priorities. As the owner of a large and varied portfolio of URM buildings as well as the local organisation responsible for assessing building safety, Auckland Council is developing exemplar inspection, assessment, prioritisation and retrofit strategies that will target the seismic risks associated with URM buildings, in particular, so as to preserve and enhance safety and the economic and community value of these special buildings. Collaboration amongst Auckland Council, The University of Auckland and GNS Science has resulted in a state-of-the-art rapid quantitative assessment program applied to a sampling of typologically representative URM buildings in Auckland.

Quantitative Interpretation of Tracks for Determination of Body Mass

To better understand the biology of extinct animals, experimentation with extant animals and innovative numerical approaches have grown in recent years. This research project uses principles of soil mechanics and a neoichnological field experiment with an African elephant to derive a novel concept for calculating the mass (i.e., the weight) of an animal from its footprints. We used the elephant's footprint geometry (i.e., vertical displacements, diameter) in combination with soil mechanical analyses (i.e., soil classification, soil parameter determination in the laboratory, Finite Element Analysis (FEA) and gait analysis) for the back analysis of the elephant's weight from a single footprint. In doing so we validated the first component of a methodology for calculating the weight of extinct dinosaurs. The field experiment was conducted under known boundary conditions at the Zoological Gardens Wuppertal with a female African elephant. The weight of the elephant was measured and the walking area was prepared with sediment in advance. Then the elephant was walked across the test area, leaving a trackway behind. Footprint geometry was obtained by laser scanning. To estimate the dynamic component involved in footprint formation, the velocity the foot reaches when touching the subsoil was determined by the Digital Image Correlation (DIC) technique. Soil parameters were identified by performing experiments on the soil in the laboratory. FEA was then used for the backcalculation of the elephant's weight. With this study, we demonstrate the adaptability of using footprint geometry in combination with theoretical considerations of loading of the subsoil during a walk and soil mechanical methods for prediction of trackmakers weight.

Does footprint depth correlate with foot motion and pressure?

Footprints are the most direct source of evidence about locomotor biomechanics in extinct vertebrates. One of the principal suppositions underpinning biomechanical inferences is that footprint geometry correlates with dynamic foot pressure, which, in turn, is linked with overall limb motion of the trackmaker. In this study, we perform the first quantitative test of this long-standing assumption, using topological statistical analysis of plantar pressures and experimental and computer-simulated footprints. In computer-simulated footprints, the relative distribution of depth differed from the distribution of both peak and pressure impulse in all simulations. Analysis of footprint samples with common loading inputs and similar depths reveals that only shallow footprints lack significant topological differences between depth and pressure distributions. Topological comparison of plantar pressures and experimental beach footprints demonstrates that geometry is highly dependent on overall print depth; deeper footprints are characterized by greater relative forefoot, and particularly toe, depth than shallow footprints. The highlighted difference between 'shallow' and 'deep' footprints clearly emphasizes the need to understand variation in foot mechanics across different degrees of substrate compliance. Overall, our results indicate that extreme caution is required when applying the 'depth equals pressure' paradigm to hominin footprints, and by extension, those of other extant and extinct tetrapods.

Experimental study of effect of geometry on reinstallation of jack-up next to footprint

Mobile jack-up drilling rigs often need to return to a site where a previous installation has left footprints in the seabed. Reinstallation near these depressions is a problematic operation because the jack-up's circular spudcan footings become subjected to eccentric and (or) inclined loading conditions. This can lead to structural failures within the jack-up legs and (or) excessive leg tilt and hull displacement. This paper reports a comprehensive set of geotechnical centrifuge experiments that investigated the effect of footprint geometry on the reinstallation response. Artificial conical shaped footprints were manually cut in the centrifuge sample, ensuring consistent shapes and minimizing any variation of undrained shear strength due to the process of initially installing and retrieving a spudcan. The effect of footprint geometry was thereby isolated. The vertical, horizontal, and moment loads induced on a model footing when penetrated at varying offsets are presented and these provide evidence on the effect of different footprint depths and angles on installation. The footprint geometry governed the horizontal force and moment observed during reinstallation between the level of the touchdown and the footprint toe. Further experimentation has shown that an equivalent skirted footing induced significantly higher horizontal forces (although it can be assumed to be significantly stiffer).

Tread wear and footprint geometrical characters of truck bus radial tires

Wear and mileage performance are the foremost performances for truck bus radial (TBR) tires. There are a lot of researches about the tire wear performance as well as the contact patch phenomenon by using finite element analysis (FEA) method or testing. But there is little published data on the correlations between the footprint geometry and the tread wear performance of tires. In this paper, an experiment on tire-ground performance of TBR tires is carried out by using Tekscan. The real-time changes of contact-area pressure distribution that occurred during the process of continuous load and unload are recorded. Three types of tires that act differently in behavior under normal usage are analyzed. A new method of researching in tire tread wear, which focuses on the geometrical characters of the footprint, is put forward. The experimental results of the three tires are described by using footprint geometrical characters. On the basis of studying the changing laws of footprint geometrical characters during the loading process and considering consumer survey and factory feedback information, the correlations between the geometrical character of footprints and tread destruction form are built. The analyzed results show that a greater contact area coefficient and a steady coefficient of contact result in a better wear performance for TBR tires. The footprint-shape coefficient changing laws in the process of loading are found to have a very good coincidence with the tread wear of the three types of tires. Tires with a smaller footprint-shape coefficient are likely to have an average tread wear while avoiding the shoulder wear first. The proposed research provides a new solution to predict tire-ground performance at the point of footprint and several useful references for improving tire design.

Geometric morphometric approach in the study of the footprint variation in children between 6 and 12 years of age

Introduction . Footprint evaluation is a widely used method for determination of foot morphology. Generally, variation in footprint have been associated to vertical variation of the plantar vault, with particular attention to the middle longitudinal arch (MLA). In the children, MLA tends to be lower and accentuates naturally when approaching adolescence (Forriol and Pascual, 1990). Thought this condition is mostly asymptomatic, permanence of lower MLA after development is associated to flatfoot. In this study the morphology of the baropodometrical footprint was analysed by using geometric morphometric approach (Slice, 2000). This method permits to quantify the geometrical look of the anatomical structures by mean of coordinate system method. Material and methods . The footprints of 50 children with age spanning from 6 to 12 years were sampled using an electronic baropodometry. The external profile of the footprints were reduced to 50 equally spaced landmarks and superimposed using the Procrustes superimposition method. A principal component analysis was performed to evaluate the morphological variability of the footprints and sex and age difference were observed. Results . geometric morphometric results show that principal variations are localized in the medial region of the isthmus and are associated to a narrowing/widening of the footprint. No sex and age differences were observed, a part from a small group with age spanning from 6 to 9 years, showing a wider footprint. Conclusions . It is thought that principal modification of the MLA occurs in the pre-school years (Stavlas et al, 2005). The results of this analysis show an high variability of the footprint geometry, suggesting that ongoing development of the foot structure takes place also during school ages. Although these results are preliminary, they should carefully considered in the treatment of the flatfoot in children, considering that the development of the foot proceeds also after 6 years

Hard X-ray properties of magnetic cataclysmic variables

Hard X-ray surveys have proven remarkably efficient in detecting intermediate polars and asynchronous polars, two of the rarest type of cataclysmic variable (CV). Here we present a global study of hard X-ray selected intermediate polars and asynchronous polars, focusing particularly on the link between hard X-ray properties and spin/orbital periods. To this end, we first construct a new sample of these objects by cross-correlating candidate sources detected in INTEGRAL/IBIS observations against catalogues of known CVs. We find 23 cataclysmic variable matches, and also present an additional 9 (of which 3 are definite) likely magnetic cataclysmic variables (mCVs) identified by others through optical follow-ups of IBIS detections. We also include in our analysis hard X-ray observations from Swift/BAT and SUZAKU/HXD in order to make our study more complete. We find that most hard X-ray detected mCVs have P_{spin}/P_{orb}<0.1 above the period gap. In this respect we also point out the very low number of detected systems in any band between P_{spin}/P_{orb}=0.3 and P_{spin}/P_{orb}=1 and the apparent peak of the P_{spin}/P_{orb} distribution at about 0.1. The observational features of the P_{spin} - P_{orb} plane are discussed in the context of mCV evolution scenarios. We also present for the first time evidence for correlations between hard X-ray spectral hardness and P_{spin}, P_{orb} and P_{spin}/P_{orb}. An attempt to explain the observed correlations is made in the context of mCV evolution and accretion footprint geometries on the white dwarf surface.