rss_2.0Geosciences FeedSciendo RSS Feed for Geosciences Feed Signal Processing Methods for Inspection of Aircraft Structural Materials<abstract> <title style='display:none'>Abstract</title> <p>Aircraft, their assemblies, and units must provide high durability and reliability, and maintain mechanical and technological characteristics throughout the life span of the aircraft. Different elements of aircraft structures work under mechanical loads, over a wide temperature range, with varying degrees of exposure to corrosive environments. Aircraft structural materials have a variation in the characteristics values and require the various testing methods for their inspection.</p> <p>In many NDT methods applied in aviation materials testing, signals that could be represented by a narrowband processes model are used. Known methods of their processing are focused on determining and analyzing the signals amplitude characteristics, but the information resource contained in phase characteristics is not used.</p> <p>In the article, the methodology for signal processing and determining phase characteristics in the time domain are discussed. It is based on the combination of the discrete Hilbert transform and the deterministic and statistical methods of the phase measurement. There are given examples of the application of the methodology for pulsed eddy current testing of electrically conductive materials and products, ultrasonic thickness measurement of products made of materials have significant ultrasonic attenuation, the realization impulse variant of acoustic impedance flaw detection of products made of composite materials. The examples have shown that the proposed signal processing methodology enables to determine new information parameters and signal characteristics for the industry, and extend the scope of known NDT methods.</p> </abstract>ARTICLE2020-07-24T00:00:00.000+00:00Can we be with Bee on Mars? Evaluating the Impact of a Rocket Flight on the Condition of Honeybees ()<abstract> <title style='display:none'>Abstract</title> <p>In paper the issue of a rocket flight impact and overall survivability of such flight by <italic>Apis mellifera</italic> (western honeybees) specimens is raised. Author claims that it is the key for using them on Mars for pollination in future, as this species is considered as one of the best pollinators, and should be examined before sending first human missions to the Red Planet. Rocket payload ‘BeeO!Logical’ was designed in order to conduct the research, the first of its kind worldwide. Its assumptions are presented along with overall descriptions of the experiments in two sounding rockets. Analysed data included survivability, carbon dioxide concentration values (respiration levels), temperature and humidity. It has been shown that <italic>A. mellifera</italic> specimens are able to survive the rocket flight. Project development possibilities are described, including widening the scope of the research with bumblebees (<italic>Bombus</italic>) and implementation of biocybernetic model of bee colony.</p> </abstract>ARTICLE2020-07-24T00:00:00.000+00:00Safety Critical Software Development Methodologies in Avionics<abstract> <title style='display:none'>Abstract</title> <p>This article summarizes avionics safety-critical software development methodologies and implications of the DO-178C standard from an Agile application perspective. We explain the safety-critical software categorization. It also outlines the main differences and advantages of different approaches to the development process, from Waterfall through the V-model to Iterative and Incremental. Agile principles are explained as well as a Scrum – which is a popular framework in the non-safety-critical software industry. The application of Agile, for safety-critical software considerations, is based on the practical knowledge of the authors, and looks at the potential solution from a DO-178C standard, size of the project, scalability, and organizational culture points of view. Definition of the Agile type of framework, consistent with the certification process and existing standards, has been highlighted as a potential game-changer for the avionics industry.</p> </abstract>ARTICLE2020-07-24T00:00:00.000+00:00Detection of the Fatigue Cracks Initiated near the Rivet Holes by Eddy Current Inspection Techniques<abstract> <title style='display:none'>Abstract</title> <p>Eddy current (EC) method is considered as most applicable for in-service detection of fatigue subsurface cracks initiated in aircraft multilayer structures near the rivet holes. At the same time, the successful solution of this problem is obstructed by additional noise created by defect-free rivets. All EC inspection techniques for the detection of subsurface cracks around the rivets can be classified into three main groups: 1) static mode – carried out by placing the EC probe concentrically on the rivet head; 2) rotational mode – when the EC probe is rotated around the rivet axle and 2) sliding mode – performed by the movement of EC probe along the rivet line or near it. All these approaches have some advantages and limitations. In this study, known EC techniques for the detection of cracks in multilayer aircraft structures are analyzed. New advanced EC techniques for the detection of fatigue cracks in internal layers of the riveted structures based on different types (ring, sliding, and rotational) probes are presented. The static EC method with developed low-height ring-type probe creates the possibility to detect cracks in the difficult of access areas. The possibility to estimate the length of detected cracks by a ring-type probe is shown. The proposed rotational remote field EC probe can detect as small as 1.0 mm long cracks under the button-head rivet and 2 mm thick upper skin with a high signal-to-noise ratio. Therefore, in many aircraft structures, fatigue cracks will be detected before a critical threshold achieved. New EC sliding techniques based on remote field and double differential probes were proposed for the rapid detection of cracks in internal layers of riveted aircraft structures. Remote-field EC probe for reliable detection of fatigue cracks in third and fourth layers of five-layer units was proposed. Another sliding technique based on a double differential EC probe gives the possibility to detect transverse cracks in the second layer without the rivet row area access. The main advantage of developed techniques is high inspection reliability due to the possibility to discriminate the signals created by cracks and defect-free rivets. Presented inspection procedures include the selective signal analysis in the complex plane diagram. Proposed EC inspection techniques were successfully implemented into the aircraft maintenance practice.</p> </abstract>ARTICLE2020-07-24T00:00:00.000+00:00The User-Preferred Optimal Flight Parameters in an Active Navigational System in a Multi-Alternative Situation<abstract> <title style='display:none'>Abstract</title> <p>The goal of this paper is to investigate the influence of the objectively existing effectiveness functions of an aircraft control system upon the control and managerial decision making process in the framework of the subjective entropy maximum princi-ple. The subjective analysis theory entropy paradigm makes it possible to consider the aircraft control system based upon personal preferences as an active system governed by an individual (active element of the control system) with the help of her/his individual subjective preferences optimal distributions obtained in conditions of operational multi-alternativeness and those operational alternatives the active system active element’s individual subjective preferences uncertainty. The described ap-proach takes into account the simple two-alternative operational situation in regards with the objectively existing effectiveness functions, related to the aircraft control system, in the view of a controlled parameter and a combination of it with its rate as the ratio. The obtained expressions for the objective functional extremal functions of the effectiveness and preferences, as well as the subjective entropy of the alternatives preferences, illustrated in diagrams visualize the situation and allow taking a good choice. The ideas of the required proper governing, managing, and control methods choice optimization with respect to only 2 alternative objective effectiveness functions arguments might be simple; nevertheless, increasing the number of parameters and further complication of the problem setting will not change the principle of the problem solution.</p> </abstract>ARTICLE2020-07-24T00:00:00.000+00:00CFD Analysis of the Tractor Propulsion Concepts for an Inverted Joined Wing Airplane<abstract> <title style='display:none'>Abstract</title> <p>Efficiency is a crucial parameter for an airplane to reduce both cost of operations and emission of pollutants. There are several airplane concepts that potentially allow for increasing the efficiency. A few of them were not investigated thoroughly enough yet. The inverted joined wing configuration, with the upper wing in front of the lower one is an example of such concept. Therefore, a project consisting of development of an experimental scaled demonstrator, and its wind tunnel and flight testing, was undertaken by consortium: Institute of Aviation, Warsaw University of Technology, Air Force Institute of Technology and a MSP company. Results led to a conclusion, that the inverted joined wing configuration allows to build an airplane with excellent performance, but its advantage against the conventional airplane is marginal because of large trimming drag of the configuration with relatively high position of the thrust vector in pusher configuration. It was applied because the demonstrator was a flying model of manned airplane and the tractor configuration would affect the pilot’s field of observation. However, in case of the UAV, this reason becomes insignificant. Therefore two configurations of tractor propulsion were tested to see, if their performance is better than the performance of original design.</p> </abstract>ARTICLE2020-07-24T00:00:00.000+00:00Estimation of Bare Soil Moisture from Remote Sensing Indices in the 0.4–2.5 mm Spectral Range<abstract><title style='display:none'>Abstract</title><p>Soil moisture content (SMC) is an important element of the environment, influencing water availability for plants and atmospheric parameters, and its monitoring is important for predicting floods or droughts and for weather and climate modeling. Optical methods for measuring soil moisture use spectral reflection analysis in the 350–2500 nm range. Remote sensing is considered to be an effective tool for monitoring soil parameters over large areas and to be more cost effective than <italic>in situ</italic> measurements. The aim of this study was to assess the SMC of bare soil on the basis of hyperspectral data from the ASD FieldSpec 4 Hi-Res field spectrometer by determining remote sensing indices and visualization based on multispectral data obtained from UAVs. Remote sensing measurements were validated on the basis of field humidity measurements with the HH2 Moisture Meter and ML3 ThetaProbe Soil Moisture Sensor. A strong correlation between terrestrial and remote sensing data was observed for 7 out of 11 selected indexes and the determination coefficient R<sup>2</sup> values ranged from 67%– 87%. The best results were obtained for the NINSON index, with determination coefficient values of 87%, NSMI index (83.5%) and NINSOL (81.7%). We conclude that both hyperspectral and multispectral remote sensing data of bare soil moisture are valuable, providing good temporal and spatial resolution of soil moisture distribution in local areas, which is important for monitoring and forecasting local changes in climate.</p></abstract>ARTICLE2021-07-01T00:00:00.000+00:00Preliminary Design for a Jet Training Aircraft<abstract><title style='display:none'>Abstract</title><p>This paper present the results of our project to develop the preliminary design of a jet trainer plane (JTP) with a two-person crew, the base version of which is intended for cadet training. We first consider the assumptions and requirements for the new aircraft, and review the parameters of existing aircraft designs in the similarly-purposed class. Next we argue for certain design choices, regarding the aircraft layout, cockpit configuration, wing location and wingform, tail scheme, and powerplant. The resulting aircraft design is calculated to have a maximum flight speed of 940 km/h, a ground-level rate of climb of 100 m/s, and a range of 1130 km. The plane’s take-off mass is calculated, in three approximations, at 2264 kg. Lastly we present the training plane’s geometrical parameters, general view, and master geometry.</p></abstract>ARTICLE2021-07-01T00:00:00.000+00:00Aerodynamic Characteristics of a Straight Wing with a Spiroid Wingtip Device<abstract><title style='display:none'>Abstract</title><p>Spiroid wingtip devices (WD) offer a promising way of improving the lift drag ratio of UAVs, but may on the other hand lead to negative aerodynamic interference of the wing with the WD and deterioration of the aerodynamic characteristics as compared to a wing without the WD. Determining the influence of the geometric parameters of a spiroid WD on aerodynamic wing characteristics, however, remains an understudied field. In our study, we investigated the influence of the following geometrical parameters on wing aerodynamic characteristics with WD: area, radius, camber angle, constriction, and pitch of the spiroid. We found that the positive effect of the WD is present at a relative radius &gt; 0.05, as well as with an increase in the lift coefficient <italic>C</italic><italic><sub>L</sub></italic> as a result of an increase in the proportion of inductive resistance. For example, with the Reynolds number Re = 2.1×10<sup>5</sup> for a rectangular wing with an aspect ratio <italic>θ</italic> = 5.12 equipped with a spiroid WD with =0.15 the quality gain is almost 10% at <italic>C</italic><italic><sub>L</sub></italic> = 0.5, and at <italic>C</italic><italic><sub>L</sub></italic> = 0.7 is almost 20% and at <italic>C</italic><italic><sub>L</sub></italic> = 0.7 – almost 20% compared to a wing without WD. Moreover, we found that a change in the camber angle WD <italic>θ</italic> provides an increase in the derivative of the lift coefficient with respect to the angle of attack in the range from <italic>θ</italic> = 0° to <italic>θ</italic> = 130°. By changing the camber angle, it is possible to increase the lift drag ratio of the layout up to 7.5% at <italic>θ</italic> = 90° compared to <italic>θ</italic> = 0° at the Reynolds number Re = 2.1×10<sup>5</sup>. From the point of view of ensuring maximum lift drag ratio and minimum inductive drag, the angle <italic>θ</italic> = 90° is the most beneficial.</p></abstract>ARTICLE2021-07-01T00:00:00.000+00:00Estimating Emissions of Harmful Exhaust Components by Aircraft Engines During the Takeoff and Landing Cycle in Airport Space<abstract><title style='display:none'>Abstract</title><p>This article examines, based on the available information and authors’ self-assessments, the environmental impact of turbine engine exhaust gases effect on the environment in the airport space during engines flight phases in the landing and takeoff cycle (LTO). The attention of aviation professionals is drawn to the fact that the amount of exhaust from the turbine engine is so significant that it may adversely change the ambient air at the airport. Consequently, increased emission level of carbon monoxide (CO), hydrocarbons (HC) during engine start-up and idle may pose a threat to the health of ramp staff. Also, high emission levels of nitrogen oxides (NO<sub>x</sub>) during takeoff, climb, cruise and descent is not without importance for the environment around the airport space. The paper gives CO<sub>2</sub>, HC, CO and NO<sub>x</sub> emission estimations based on ICAO Engine Emission Data Bank and the number of passenger operations at a medium-sized airport. It also provides calculation results of aircraft CO<sub>2</sub>, HC, CO and NO<sub>x</sub> emission using average times of aircraft maneuvers taken from aircraft Flight Data Recorder (FDR) in the LTO cycle various aircraft types at the airport. The latter, based on actual maneuvering times, lead to significantly reduced estimates of toxic exhaust gas emission volumes.</p></abstract>ARTICLE2021-07-01T00:00:00.000+00:00An Alternative Ballistic Limit Equation for the Whipple Shield in the Shatter Regime, Based on Characteristics of the Large Central Fragment<abstract><title style='display:none'>Abstract</title><p>In the shatter regime of a Whipple shield, a large central fragment makes a significant contribution to the damage-causing capacity of the debris cloud. Herein we present a feasible scheme for the identification and measurement of this large central fragment and propose an alternative approach to the ballistic limit equation (BLE) for the Whipple shield, deducing an alternative ballistic limit in the shatter regime based on the large central fragment’s characteristics. This alternative BLE is compared with the phenomenological Whipple BLE, the JSC Whipple BLE and the Ryan curve. Our alternative BLE, modified at the incipient fragmentation and completed fragmentation point, is shown to agree well with experimental results.</p></abstract>ARTICLE2021-07-01T00:00:00.000+00:00Using Adverse Event Pyramids to Assess Probabilities in Airline Safety Management<abstract><title style='display:none'>Abstract</title><p>This article reviews the methods of safety management using Heinrich’s and Bird’s pyramids. The presence of a causal relationship between pyramid levels, as a result of inconsistencies in the activities of an organization and personnel, lead to incidents, and incidents in turn lead to accidents. The existence of such a relationship makes it possible to predict the risk of “top-level” events by reducing risks at the middle and lower levels. A mathematical description of the development process of an undesired aviation event is presented, which makes it possible to evaluate the probability of the successful (or unsuccessful) completion of a transportation task. Also given is an analysis of the development of an aviation accident, based on the example of the crash of a Lufthansa A-320 aircraft on 14 September 1993 at the airport of Warsaw (Poland) while landing in adverse weather conditions.</p></abstract>ARTICLE2021-07-01T00:00:00.000+00:00Stereophotogrammetry for 2-D building deformation monitoring using Kalman Filter<abstract> <title style='display:none'>Abstract</title> <p>Stereo photogrammetry has been used in this study to analyse and detect movements within the Lecture theater of School of Environmental Technology of Federal University of Technology Minna via the use of Kalman filter algorithm. The essential steps for implementation of this method are herein highlighted and results obtained indicate Ins. Mov.s (velocity) ranging from ±0.0000001 m/epoch to ±0.000007 m/epoch with greater movements noticed in the horizontal direction than in the vertical direction of the building. Because the observed movements were insignificant, the building has been classified as stable. However, a longer period of observation with a bi-monthly observational interval has been recommended to enable decision on the rate of rise/sink and deformation of the building.</p> </abstract>ARTICLE2020-08-07T00:00:00.000+00:00Development of a UAV-based system for the semi-automatic estimation of the volume of earthworks<abstract> <title style='display:none'>Abstract</title> <p>One of the challenges faced by surveyors in acquisition of accurate spatial data for mining applications is the risk involved in acquiring data in rugged terrains and difficult or inaccessible areas. With the advent of modern technology, accurate geospatial data can now be safely obtained for proper mining documentation periodically. The use of Unmanned Aerial Vehicles (UAVs) for data acquisition in mine surveying has been a viable means of obtaining reliable geospatial data rapidly and efficiently. The main goal of this study is to develop a semi-automatic UAV-based system for the acquisition of spatial data required for the estimation of the volume of earthworks. A DJI Phantom 4 quadcopter was used for the acquisition of image data of the project site, while the images were processed into a Digital Elevation Model (DEM) using Pix4Dmapper v2.0.1, which was then imported into the MATLAB-based system developed for the automatic estimation of the volume of earthworks. The volume obtained from the automated system was thus compared with the volume obtained directly from the Pix4Dmapper software, having specified a contour interval of 1 and an allowable error rate of ±3% as the standard error. While ±1.02% error was observed in the volume estimated using the Pix4Dmapper, the developed automated system yielded an estimated precision of ±0.81% in its volume estimation, which proves to be more robust for automatic volume estimation in terms of accuracy and precision.</p> </abstract>ARTICLE2020-12-31T00:00:00.000+00:00Legal aspects of registration the time of cadastral data creation or modification<abstract> <title style='display:none'>Abstract</title> <p>In Poland, the cadastre is the basic register which is the source of information on cadastral entities and their property. Therefore, it should constitute a reliable source of information in the scope of establishing the range of law, its nature, but also the subject of its ownership. However, it is necessary to be able to not only check the current information on the legal status and its scope, but also review past statuses or determine the rights that will influence real estate in the future. The cadastre and related rights are changing very dynamically over time, and each state has a very strict reference to the previous state. Therefore, in order to manage real estate in the most effective way, it is necessary to record temporal attributes of cadastre objects.</p> <p>The main objective of this paper is to define the legal issues related to the possibility of registration at the time of creation or modification of object in the Polish cadastre. This paper includes analyses of both Polish legal regulations and European standards and norms. Moreover, the article presents the results of comparative analyses concerning the data model of cadastre and INSPIRE and Land Administration Domain Model (LADM) data models for the theme cadastral parcel in terms of temporal aspect.</p> </abstract>ARTICLE2020-09-25T00:00:00.000+00:00Monitoring and forecasting spatio-temporal LULC for Akure rainforest habitat in Nigeria<abstract> <title style='display:none'>Abstract</title> <p>For several decades, Nigerian cities have been experiencing a decline in their biodiversity resulting from rapid land use land cover (LULC) changes. Anticipating short/long-term consequences, this study hypothesised the effects of LULC variables in Akure, a developing tropical rainforest city in south-west Nigeria. A differentiated trend of urban LULC was determined over a period covering 1999–2019. The study showed the net change for bare land, built-up area, cultivated land, forest cover and grassland over the two decades to be −292.68 km<sup>2</sup>, +325.79 km<sup>2</sup>, +88.65 km<sup>2</sup>, +8.62 km<sup>2</sup> and −131.38 km<sup>2</sup>, respectively. With a projected population increase of about 46.85%, the study identified that the built-up land cover increased from 1.98% to 48.61%. The change detection analysis revealed an upsurge in built area class. The expansion indicated a significant inverse correlation with the bare land class (50.97% to 8.66%) and grassland class (36.33% to 17.94%) over the study period. The study observed that the land consumption rate (in hectares) steadily increased by 0.00505, 0.00362 and 0.0687, in the year 1999, 2009 and 2019, respectively. This rate of increase is higher than studies conducted in more populated cities. The Cellular Automata (CA) Markovian analysis predicted a 37.92% growth of the study area will be the built-up area in the next two decades (2039). The 20-year prediction for Akure built-up area is within range when compared to CA Markov prediction for other cities across the globe. The findings of this study will guide future planning for rational LULC evaluation.</p> </abstract>ARTICLE2020-12-31T00:00:00.000+00:00FEM modelling of the static behaviour of reinforced concrete beams considering the nonlinear behaviour of the concrete<abstract><title style='display:none'>Abstract</title><p>This paper presents a finite element (FE) method of modelling reinforced concrete beams. The proposed model takes into account the phenomena characteristic of reinforced concrete structures, such as the interaction between two materials (concrete and steel), the cracking caused by mechanical loads and the variation of the Young's modulus under increasing load. A relevant numerical FE analysis was carried out in the ABAQUS system using the concrete damaged plasticity (CDP) model. The character of Young's modulus variation due to increasing stress intensity level was taken from the author's own research. The results of the FE calculations were compared with the results yielded by the author's numerical bar model.</p></abstract>ARTICLE2021-07-25T00:00:00.000+00:00Gauss-Markov model with random parameters to adjust results of surveys of geodetic control networks<abstract> <title style='display:none'>Abstract</title> <p>Alignment of an engineering object project in the field is always conducted at the points of the geodetic control network, the coordinates of which are determined on the basis of the results of its elements survey and with connection to the national spatial reference system. The points of the national spatial reference system determined on the basis of previous surveys have specified coordinates with adequate accuracy, which is included in their covariance matrix. The coordinates of the geodetic control network points are determined more accurately than the points of the national spatial reference system and this means that the results of surveys of the geodetic control network have to be adequately incorporated into the coordinates of the reference points. In order to perform this incorporation, it may be assumed that the coordinates of the reference points are random, that is, they have a covariance matrix, which should be used in the process of adjusting the results of the geodetic control network observation. This research paper presents the principles for the estimation of the Gauss-Markov model parameters applied in case of those geodetic control networks in which the coordinates of the reference points have random character. On the basis of the observation equations δ + <bold>AX</bold> = <bold>L</bold> for the geodetic control network and using the weighting matrix <bold>P</bold> and the matrix of conditional covariances (<bold>P</bold><sup>−1</sup> + <bold>AC</bold><sub><italic>X</italic></sub><bold>A</bold><sup><italic>T</italic></sup>) for the observation vector <bold>L</bold>, the parameter vector <bold>X</bold> is estimated in the form of the derived formula <inline-formula> <alternatives> <inline-graphic xmlns:xlink="" xlink:href="graphic/j_rgg-2021-0001_ieq_001.png"/> <mml:math xmlns:mml="" display="inline"><mml:mrow><mml:mover accent="true"><mml:mtext mathvariant="bold">X</mml:mtext><mml:mo>^</mml:mo></mml:mover><mml:mo>=</mml:mo><mml:msup><mml:mrow><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:msubsup><mml:mtext mathvariant="bold">C</mml:mtext><mml:mi>X</mml:mi><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msubsup><mml:mo>+</mml:mo><mml:msup><mml:mtext mathvariant="bold">A</mml:mtext><mml:mi>T</mml:mi></mml:msup><mml:mtext mathvariant="bold">PA</mml:mtext></mml:mrow><mml:mo>)</mml:mo></mml:mrow></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup><mml:msup><mml:mtext mathvariant="bold">A</mml:mtext><mml:mi>T</mml:mi></mml:msup><mml:mtext mathvariant="bold">P</mml:mtext><mml:mo>⋅</mml:mo><mml:mtext mathvariant="bold">L</mml:mtext></mml:mrow></mml:math> <tex-math>{\bf{\hat X}} = {\left( {{\bf{C}}_X^{ - 1} + {{\bf{A}}^T}{\bf{PA}}} \right)^{ - 1}}{{\bf{A}}^T}{\bf{P}} \cdot {\bf{L}}</tex-math> </alternatives> </inline-formula> . The verification of these estimation principles has been illustrated by the example of a fragment of a levelling geodetic control network consisting of three geodetic control points and two reference points of the national spatial reference system.</p> <p>The novel feature of the proposed solution is the application of covariance matrices of the reference point coordinates to adjust the results of the survey of geodetic control networks and to determine limit standard deviations for the estimated coordinates of geodetic control network points.</p> </abstract>ARTICLE2021-07-25T00:00:00.000+00:00 as related to real estate influenced by railway noise in the context of allowable indicators that have been recently modified in Poland<abstract><title style='display:none'>Abstract</title><p>The paper deals with the problem of rail noise pollution in cities in the context of legal amendments. This aspect is often neglected in the process of spatial planning. The authors were motivated to undertake this analysis both by legal changes permitting higher levels of acceptable noise thresholds, which were introduced and legalised in October 2012, and by the intensified levels of investment in areas neighbouring railways. On selected examples of residential areas in Warsaw, Poland (the city districts of Ursus, Białołęka and Ursynów), relevant land development sites were analysed against the course of isophones showing permissible noise levels. The analysis was based on data taken from acoustic maps for Warsaw from 2012 and 2017, planning studies, the Topographic Objects Database (BDOT10k) and the current state of land development. Using ArcGis software, 22 features, three study areas, and corresponding quantitative indicators were assessed. The authors presented the level of railway noise pollution set against the general spatial development. The analysis demonstrated that the changes in legislation have resulted in the “acoustic release” of land near railways; i.e., in these areas new, less-restrictive regulations on noise pollution have become permissible. In turn, the number of buildings that were considered at risk of noise pollution before 2012 has fallen.</p><p>The aforementioned regulatory changes may unfavourably impact residential areas neighbouring railways and this has even provoked a wider discussion at the European Union level.</p></abstract>ARTICLE2021-07-25T00:00:00.000+00:00 comparing extrinsic and intrinsic maps with univariate maps<abstract><title style='display:none'>Abstract</title><p>Multivariate mapping is a technique in which multivariate data are encoded into a single map. A variety of design solutions for multivariate mapping refers to the number of phenomena mapped, the map type, and the visual variables applied. Unlike other authors who have mainly evaluated bivariate maps, in our empirical study we compared three solutions when mapping four variables: two types of multivariate maps (intrinsic and extrinsic) and a simple univariate alternative (serving as a baseline). We analysed usability performance metrics (answer time, answer accuracy, subjective rating of task difficulty) and eye-tracking data. The results suggested that experts used all the tested maps with similar results for answer time and accuracy, even when using four-variable intrinsic maps, which is considered to be a challenging solution. However, eye-tracking data provided more nuances in relation to the difference in cognitive effort evoked by the tested maps across task types.</p></abstract>ARTICLE2021-07-25T00:00:00.000+00:00en-us-1