ALBERT

Description: Relying on nationally representative data from the most recent wave of the National Survey of Black Americans (NSBA), the current study examines how past and present neighborhood racial composition is associated with feelings of closeness toward black Americans, black Africans, and black West Indians. In addition, this research tests whether race-based socialization messages received from caregivers or religious socialization messages explain this relationship among a sample from the adult black US population. The findings show that past neighborhood composition is associated with present feelings of closeness toward black Americans and black West Indians but are not associated with close feelings toward black Africans. Current neighborhood racial composition is not associated with feelings of closeness toward any of the groups. Racial socialization messages are associated with closeness towards them all but are found to be largely a function of having a two-parent family during childhood. Religious socialization is also associated with intraracial feelings of closeness. Results suggest that neighborhood racial composition is important to help facilitate positive feelings toward others who share the same race but a different ethnicity.

Description: Automatic Dependent Surveillance-Broadcast (ADS-B) is an air traffic surveillance technology in which aircraft transmit position and identification. The development of space-based ADS-B will allow precise control of aircraft in areas that are not covered by radar, such as oceanic regions and high latitudes. The Royal Military College of Canada has developed a spaceborne ADS-B receiver scheduled to fly on the Canadian Advanced Nanospace eXperiment-7 (CanX-7) satellite. The payload is planned to collect data over the North Atlantic region, which will then be compared to truth data provided by air traffic services. A model was created to determine power levels arriving at the satellite to provide confidence in the ADS-B receiver and antenna proposed for CanX-7. The model takes into account neutral atmosphere and ionospheric effects, aircraft-satellite geometry, and antenna radiation patterns. A simulation was run by inserting real aircraft data from the North Atlantic Track System into the model and placing the satellite at altitudes of 400, 600, and 800 km. Results of the simulation indicate that power received at the satellite, ranging between −98.5 dBm and −103 dBm for the selected altitudes, will be sufficient to successfully conduct the mission.

Description: This paper evaluates the independent effect of the spatial proximity of green urban areas upon the individual subjective well-being of the Milan population (Italy). The methodology is based on a survey undertaken in 2010 using a sample of 1,000 of Milan citizens. Univariate and multivariate analyses and GIS localization have been employed in order to rank the major individual well-being determinants and the relationship between citizens and urban green areas. Results show that the residential proximity of citizens to urban green areas seems to have little bearing on individual subjective well-being.

Description: This paper addresses the development of the simulation of the low-level control system for the underwater remotely operated vehicle Visor3. The 6-DOF mathematical model of Visor3 is presented using two coordinated systems: Earth-fixed and body-fixed frames. The navigation, guidance, and control (NGC) structure is divided into three layers: the high level or the mission planner; the mid-level or the path planner; and the low level formed by the navigation and control systems. The nonlinear model-based observer is developed using the extended Kalman filter (EKF) which uses the linearization of the model to estimate the current state. The behavior of the observer is verified through simulations using Simulink®. An experiment was conducted with a trajectory that describes changes in the and and yaw components. To accomplish this task, two algorithms are compared: a multiloop PID and PID with gravity compensation. These controllers and the nonlinear observer are tested using the 6-DOF mathematical model of Visor3. The control and navigation systems are a fundamental part of the low-level control system that will allow Visor3’s operators to take advantage of more advanced vehicle’s capabilities during inspection tasks of port facilities, hydroelectric dams, and oceanographic research.

Description: The lower-class segment of the population of the developing nations often fails to form meaningful social relations and remain disengaged from essential social institutions. The research examines those people who live in refugee-camp and sullied slum of Dhaka city and inspect how much they are socially isolated. Certain characteristics, taken as indicators to test the level of social isolation, indicate that a large segment of camp and slum dwellers are feeling isolated. However, the evidence shows no differences in the predicted direction with respect to the objective demographic variables; nonetheless, a pattern of perceived social isolation was found from the survey data.

Description: This study presents the analysis of Akure urban land use change detection from remote imagery perspective. Efforts were made to examine the direction that the continuous expansion of the city tends towards since its inception as a state capital in 1976. Using Aerial Imagery Overlay (AIO), the pattern of land use changes in Akure and its environs were determined. This involves imageries interpolation and overlaying to determine the land use changes, direction, and extent of the expansion. Findings revealed unguided expansion in the growth of the city which affects the pattern of land uses within the city and, by extension, into the adjoining settlements. There were incompatible conversions in land uses and undue encroachment into green areas in the adjoining communities. The study suggests effective zoning strategy on unguided nature of urban development whose effects on land use are very prominent in the study area. Adequate monitoring by the Development Control Department and other stakeholders in urban planning is equally suggested to mitigate the incompatible land use changes in the area.

Description: This paper investigates the accuracy of six measures of housing cost differences among US metropolitan areas. Using Census data from 177 metropolitan areas, it tests the measures in two ways. First, it tests the ability of changes in the measures to predict changes in the shelter component of the metropolitan CPI from 1990 to 2000. Second, it tests the ability of the measures themselves to predict a proxy in 2000. A measure based on Fair Market Rents calculated by HUD placed second on the first test but did badly on the second. The housing component of the ACCRA index, a living cost measure frequently used by researchers, performed poorly on both tests. The top performer on both tests was a measure based on the average rent per room for a metropolitan area’s dwellings. Researchers wishing to control for living cost differences among places should consider including it in their living cost index.

Description: This paper demonstrates that automatic selection of the right interpolation/smoothing method in a GNSS-based network real-time kinematic (NRTK) interpolation segment can improve the accuracy of the rover position estimates and also the processing time in the NRTK processing center. The methods discussed and investigated are inverse distance weighting (IDW); bilinear and bicubic spline interpolation; kriging interpolation; thin-plate splines; and numerical approximation methods for spatial processes. The methods are implemented and tested using GNSS data from reference stations in the Norwegian network RTK service called CPOS. Data sets with an average baseline between reference stations of 60–70 km were selected. 12 prediction locations were used to analyze the performance of the interpolation methods by computing and comparing different measures of the goodness of fit such as the root mean square error (RMSE), mean square error, and mean absolute error, and also the computation time was compared. Results of the tests show that ordinary kriging with the Matérn covariance function clearly provides the best results. The thin-plate spline provides the second best results of the methods selected and with the test data used.

Description: This paper deals with the design of a fault detection and isolation (FDI) system for an intelligent vehicle, a vehicle equipped with advanced driver assistance system (ADAS). The ADASs are outfitted with sensors for acquiring various information about the vehicle and its surroundings. Since these sensors are sensitive to faults, an efficient FDI system should be developed. The designed FDI system is comprised of three parts: a detection part, a decision part, and a fault management part. The detection part applies a generalized observer scheme (GOS). In the GOS, there is bank of extended Kalman filters (EKFs), each excited by all except one sensor measurement. The residual generated from the measurement update of each EKF is therefore sensitive to all sensor faults but one. This way, the fault sensitivity pattern of the residual makes it possible to detect a fault and locate the faulty sensor. The designed FDI system has been implemented and tested off-line with actual experiment data. Good results have been obtained with diagnosing individual sensor faults and outputting fault-free vehicle states.

Description: We test whether ethnic diversity in Dutch neighbourhoods and municipalities drives down associational involvement and build on earlier research in two important ways. First, we explicitly take into account the ethnic composition of local voluntary associations, distinguishing involvement in bonding (only in-group members) and bridging (with out-group members) associations. Second, we aim to explain relationships between ethnic diversity and associational involvement, testing two competing sets of predictions derived from conflict and contact theories. Using data from the Netherlands Longitudinal Lifecourse Study (2013), ethnic diversity turns out to hardly affect associational involvement negatively. Only for leisure associations, living in ethnically more diverse municipalities substantially decreases the likelihood to be involved in bonding associations, whereas higher levels of neighbourhood ethnic diversity increase the likelihood to be involved in bridging associations. Moreover, ethnic diversity indirectly affects associational involvement via interethnic contact. Higher levels of ethnic diversity increase interethnic contact which, in turn, is negatively related to involvement in bonding associations. Whereas higher levels of ethnic diversity in neighbourhoods increase perceptions of ethnic threat, these perceptions decrease with higher levels of ethnic diversity in the municipality. Perceptions of ethnic threat do not, however, affect associational involvement. Our results shed more light on the direct and indirect relationships between ethnic diversity and bonding and bridging associational involvement.

Description: This study was conducted with the objective of finding the perceivable effect of figures and backgrounds on residential streetscapes and their connections in visual complexity. The visual complexity depends on the extent of information a viewer can observe from a visible area. The information includes a number of visual elements along the streetscapes and their diversity and interconnections. The aim of this research was to analyze the structural hierarchical visual complexity of the streetscapes, caused by varied spatial arrangement and numerous spatial connections of the perceivable visual elements. The visual elements of 60 residential streetscapes were classified into figures and backgrounds using human perception of 20 subjects. The identified figures and backgrounds were arranged in a taxonomic diagram representing their connections. These taxonomic diagrams reflect the structural hierarchical visual complexity. Finally, taxonomic entropy was applied to statistically analyze the structural hierarchical visual complexity. When the taxonomic diagram is vertically and horizontally lengthy and the arrangement of the elements of taxonomic diagram is irregular, the complexity increases depicting a large number of figures whose spatial connections impart a high visual complexity to the streetscapes.

Description: Multipath propagation is one of the major sources of error in GPS measurements. In this research, a ray-tracing technique is proposed to study the frequency domain characteristics of multipath propagation. The Doppler frequency difference, also known as multipath phase rate and fading frequency, between direct (line-of-sight, LOS) and reflected (non-line-of-sight, NLOS) signals is studied as a function of satellite elevation and azimuth, as well as distance between the reflector and the static receiver. The accuracy of the method is verified with measured Doppler differences from real data collected in a downtown environment. The use of ray-tracing derived predicted Doppler differences in a receiver, as a means of alleviating the multipath induced errors in the measurement, is presented and discussed.

Description: With modern global navigation satellite system (GNSS) signals, the FFT-based parallel code search acquisition must handle the frequent sign transitions due to the data or the secondary code. There is a straightforward solution to this problem, which consists in doubling the length of the FFTs, leading to a significant increase of the complexity. The authors already proposed a method to reduce the complexity without impairing the probability of detection. In particular, this led to a 50% memory reduction for an FPGA implementation. In this paper, the authors propose another approach, namely, the splitting of a large FFT into three or five smaller FFTs, providing better performances and higher flexibility. For an FPGA implementation, compared to the previously proposed approach, at the expense of a slight increase of the logic and multiplier resources, the splitting into three and five allows, respectively, a reduction of 40% and 64% of the memory, and of 25% and 37.5% of the processing time. Moreover, with the splitting into three FFTs, the algorithm is applicable for sampling frequencies up to 24.576 MHz for L5 band signals, against 21.846 MHz with the previously proposed algorithm. The algorithm is applied here to the GPS L5 and Galileo E5a, E5b, and E1 signals.

Description: The knowledge of environmental maps (i.e., map-awareness) can appreciably improve the accuracy of optimal methods for position estimation in indoor scenarios. This improvement, however, is achieved at the price of a significant complexity increase with respect to the case of map-unawareness, specially for large maps. This is mainly due to the fact that optimal map-aware estimation algorithms require integrating highly nonlinear functions or solving nonlinear and nonconvex constrained optimization problems. In this paper, various techniques for reducing the complexity of such estimators are developed. In particular, two novel strategies for restricting the search domain of map-aware position estimators are developed and the exploitation of state-of-the-art numerical integration and optimization methods is investigated; this leads to the development of a new family of suboptimal map-aware localization algorithms. Our numerical and experimental results evidence that the accuracy of these algorithms is very close to that offered by their optimal counterparts, despite their significantly lower computational complexity.

Description: An attitude estimation algorithm is developed using an adaptive extended Kalman filter for low-cost microelectromechanical-system (MEMS) triaxial accelerometers and gyroscopes, that is, inertial measurement units (IMUs). Although these MEMS sensors are relatively cheap, they give more inaccurate measurements than conventional high-quality gyroscopes and accelerometers. To be able to use these low-cost MEMS sensors with precision in all situations, a novel attitude estimation algorithm is proposed for fusing triaxial gyroscope and accelerometer measurements. An extended Kalman filter is implemented to estimate attitude in direction cosine matrix (DCM) formation and to calibrate gyroscope biases online. We use a variable measurement covariance for acceleration measurements to ensure robustness against temporary nongravitational accelerations, which usually induce errors when estimating attitude with ordinary algorithms. The proposed algorithm enables accurate gyroscope online calibration by using only a triaxial gyroscope and accelerometer. It outperforms comparable state-of-the-art algorithms in those cases when there are either biases in the gyroscope measurements or large temporary nongravitational accelerations present. A low-cost, temperature-based calibration method is also discussed for initially calibrating gyroscope and acceleration sensors. An open source implementation of the algorithm is also available.

Description: Examining the performance of the GNSS PLL, this paper presents novel results describing the statistical properties of four popular phase estimators under both strong- and weak-signal conditions when subject to thermal noise, deterministic dynamics, and typical pedestrian motion. Design routines are developed which employ these results to enhance weak-signal performance of the PLL in terms of transient response, steady-state errors, and cycle-slips. By examining both single and data-pilot signals, it is shown that appropriate design and tuning of the PLL can significantly enhance tracking performance, in particular when used for pedestrian applications.

Description: With modern global navigation satellite system (GNSS) signals, the FFT-based parallel code search acquisition must handle the frequent sign transitions due to the data or the secondary code. There is a straightforward solution to this problem, which consists in doubling the length of the FFTs, leading to a significant increase of the complexity. The authors already proposed a method to reduce the complexity without impairing the probability of detection. In particular, this led to a 50% memory reduction for an FPGA implementation. In this paper, the authors propose another approach, namely, the splitting of a large FFT into three or five smaller FFTs, providing better performances and higher flexibility. For an FPGA implementation, compared to the previously proposed approach, at the expense of a slight increase of the logic and multiplier resources, the splitting into three and five allows, respectively, a reduction of 40% and 64% of the memory, and of 25% and 37.5% of the processing time. Moreover, with the splitting into three FFTs, the algorithm is applicable for sampling frequencies up to 24.576 MHz for L5 band signals, against 21.846 MHz with the previously proposed algorithm. The algorithm is applied here to the GPS L5 and Galileo E5a, E5b, and E1 signals.

Description: We present a comparative study of computational methods for estimation of ionospheric scintillation indices. First, we review the conventional approaches based on Fourier transformation and low-pass/high-pass frequency filtration. Next, we introduce a novel method based on nonparametric local regression with bias Corrected Akaike Information Criteria (AICC). All methods are then applied to data from the Norwegian Regional Ionospheric Scintillation Network (NRISN), which is shown to be dominated by phase scintillation and not amplitude scintillation. We find that all methods provide highly correlated results, demonstrating the validity of the new approach to this problem. All methods are shown to be very sensitive to filter characteristics and the averaging interval. Finally, we find that the new method is more robust to discontinuous phase observations than conventional methods.

Description: This paper addresses the development of the simulation of the low-level control system for the underwater remotely operated vehicle Visor3. The 6-DOF mathematical model of Visor3 is presented using two coordinated systems: Earth-fixed and body-fixed frames. The navigation, guidance, and control (NGC) structure is divided into three layers: the high level or the mission planner; the mid-level or the path planner; and the low level formed by the navigation and control systems. The nonlinear model-based observer is developed using the extended Kalman filter (EKF) which uses the linearization of the model to estimate the current state. The behavior of the observer is verified through simulations using Simulink®. An experiment was conducted with a trajectory that describes changes in the and and yaw components. To accomplish this task, two algorithms are compared: a multiloop PID and PID with gravity compensation. These controllers and the nonlinear observer are tested using the 6-DOF mathematical model of Visor3. The control and navigation systems are a fundamental part of the low-level control system that will allow Visor3’s operators to take advantage of more advanced vehicle’s capabilities during inspection tasks of port facilities, hydroelectric dams, and oceanographic research.

Description: Research on urban heat island (UHI) mitigation has been carried out globally. Several strategies have been proposed or developed to mitigate UHI, including highly reflective (HR) envelopes of buildings, green roofs, urban vegetation, shading, heat sinks, and air-conditioning efficiency. Among these techniques, HR envelopes have been extensively studied as an effective method to mitigate the UHI effect by reducing energy consumption. However, because most of HR materials are diffusive, HR envelopes applied to vertical surfaces can reflect both onto roads and nearby buildings. Additionally, HR roofs cannot reflect all incoming solar radiation to the sky if there are high buildings around it. Thus, HR materials applied as building envelopes have a limited effect against the solar contribution to the UHI. In order to solve this problem, retroreflective (RR) materials, which reflect the solar radiation back towards the source, have been studied and developed to be applied as building envelopes instead of HR materials. This paper summarizes several previous researches on HR envelopes and cool roofs and summarizes several current researches on RR materials. The potential for application of RR envelopes in cities is proposed with consideration of economic and environmental factors.

Description: Examining the performance of the GNSS PLL, this paper presents novel results describing the statistical properties of four popular phase estimators under both strong- and weak-signal conditions when subject to thermal noise, deterministic dynamics, and typical pedestrian motion. Design routines are developed which employ these results to enhance weak-signal performance of the PLL in terms of transient response, steady-state errors, and cycle-slips. By examining both single and data-pilot signals, it is shown that appropriate design and tuning of the PLL can significantly enhance tracking performance, in particular when used for pedestrian applications.

Description: The knowledge of environmental maps (i.e., map-awareness) can appreciably improve the accuracy of optimal methods for position estimation in indoor scenarios. This improvement, however, is achieved at the price of a significant complexity increase with respect to the case of map-unawareness, specially for large maps. This is mainly due to the fact that optimal map-aware estimation algorithms require integrating highly nonlinear functions or solving nonlinear and nonconvex constrained optimization problems. In this paper, various techniques for reducing the complexity of such estimators are developed. In particular, two novel strategies for restricting the search domain of map-aware position estimators are developed and the exploitation of state-of-the-art numerical integration and optimization methods is investigated; this leads to the development of a new family of suboptimal map-aware localization algorithms. Our numerical and experimental results evidence that the accuracy of these algorithms is very close to that offered by their optimal counterparts, despite their significantly lower computational complexity.

Description: This paper presents a study of differential AoA (Angle-of-Arrival) based 2D localization method utilizing FM radio signals (88 MHz–108 MHz) as Signals of Opportunity (SOP). Given prior knowledge of the transmitters’ position and signal characteristics, the proposed technique utilizes triangulation to localize receiver’s 2D position. Dual antenna interferometry provides the received signals’ AoA required for triangulation. Reliance on precise knowledge of antenna system’s orientation is removed by utilizing differential Angle of Arrivals (dAoAs). The 2D localization accuracy is improved by utilizing colocated transmitters, a concept proposed in this paper as supertowers. Analysis, simulation, and ground-based experiments have been presented; results showed that when the SNR (Signal-to-Noise Ratio) is higher than 45 dB, the proposed method localizes the receiver’s 2D position with an error of less than 15 m.

Description: This paper presents an acoustic indoor localization system for commercial smart phones that emit high pitched acoustic signals beyond the audible range. The acoustic signals with an identifier code modulated on the signal are detected by self-built receivers which are placed at the ceiling or on walls in a room. The receivers are connected in a Wi-Fi network, such that they synchronize their clocks and exchange the time differences of arrival (TDoA) of the received chirps. The location of the smart phone is calculated by TDoA multilateration. The precise time measuring of sound enables high precision localization in indoor areas. Our approach enables applications that require high accuracy, such as finding products in a supermarket or guiding blind people through complicated buildings. We have evaluated our system in real-world experiments using different algorithms for calibration-free localization and different types of sound signals. The adaptive GOGO-CFAR threshold enables a detection of 48% of the chirp pulses even at a distance of 30 m. In addition, we have compared the trajectory of a pedestrian carrying a smart phone to reference positions of an optic system. Consequently, the localization error is observed to be less than 30 cm.

Description: An extensive body of literature suggests that physical environment, physical activity, and socioeconomic status (SES) are intrinsically linked to each other and to weight related health problems. In this study, the role of objective and perceived pedestrian environment characteristics (microscale measures) was explored in relation to people’s recreational walking patterns in two neighborhoods with opposite SES. A total of 441 street segments were assessed and a total of 133 questionnaires were conducted. The findings suggest that recreational walking can take place beyond a neighborhood’s suggested SES when objective and especially perceived microscale characteristics (pedestrian environment) are favorable.

Description: Violence by young people is one of the most visible forms of social disorder in urban settlements. This study assesses the causes and consequences of youth violence in the Kumasi metropolis. The study design was a nonexperimental cross-sectional survey. A mixed method approach facilitated the random sampling of 71 young people in the Kumasi metropolis through a stratified procedure between December 2014 and November 2015. Ten (10) participants were purposively selected and enrolled in a focus group discussion. Descriptive statistics formed the basis for the analysis. This was supported with a matched discourse analysis of the emerging themes. More than half of the youth (39, 54.9%) demonstrated history of ever engaging in violence in the past one year of whom 24 (61.5%) were without formal education. The frequency of the violence perpetuation ranged from daily engagement (3, 4%) to weekly engagement in violence (12, 17%). Principally, the categories of youth violence were manifested in noise making, rape, murder, stealing, drug addiction, obscene gestures, robbery, sexual abuse, and embarrassment. Peer pressure and street survival coping approaches emerged as the pivotal factors that induced youth violence. Addressing youth violence requires an integrative framework that incorporates youth perspectives, government, chiefs, and nongovernmental organizations in Ghana, and religious bodies.

Description: This paper seeks to examine the ethnoreligious urban violence and residential mobility in the city of Kaduna with a view to make recommendations towards ameliorating its effects by evaluating the causal factors fueling the crisis and examining the pattern and direction of the residential mobility in the city. The sources of data were both primary and secondary. The sampling technique used was purposive and random sampling from two residential districts from both the northern and southern parts of the city. A total of 1,000 questionnaires were administered within the study areas and 900 questionnaires were collected. Face-to-face interviews were conducted with major stakeholders from the two parts. The data obtained were analysed using thematic and content analysis for the qualitative data whilst the quantitative data were analysed using simple percentages. The results revealed that the factors causing the ethnoreligious urban violence and residential mobility are unemployment, social institutional breakdown, politics, and colonial impact and the pattern/direction of the residential mobility in the city of Kaduna show a clear polarization along religious lines based reactive residential mobility between the two parts of the city. Based on these results recommendations were made to assist the academia, practitioners, and policy makers.

Description: High frequency (HF) radar installations are becoming essential components of operational real-time marine monitoring systems. The underlying technology is being further enhanced to fully exploit the potential of mapping sea surface currents and wave fields over wide areas with high spatial and temporal resolution, even in adverse meteo-marine conditions. Data applications are opening to many different sectors, reaching out beyond research and monitoring, targeting downstream services in support to key national and regional stakeholders. In the CALYPSO project, the HF radar system composed of CODAR SeaSonde stations installed in the Malta Channel is specifically serving to assist in the response against marine oil spills and to support search and rescue at sea. One key drawback concerns the sporadic inconsistency in the spatial coverage of radar data which is dictated by the sea state as well as by interference from unknown sources that may be competing with transmissions in the same frequency band. This work investigates the use of Machine Learning techniques to fill in missing data in a high resolution grid. Past radar data and wind vectors obtained from satellites are used to predict missing information and provide a more consistent dataset.

Description: Shrinking populations have been gaining increasing attention, especially in postsocialist Eastern and Central European countries. While most studies focus on specific cities and regions, much less is known about the spatial dimension of population decline on the national level and the local factors determining spatially uneven population change. This study uses Lithuanian census data from the years 2001 to 2011 to get insight into the geography of population change for the whole country. Lithuania has experienced one of the highest rates of population decline in the world in the last decades. The predictive models show that regional factors have a strong effect on the variation in population change throughout the country but also reveal that sociodemographic and economic area characteristics play a role in the process of decline. Our results give little hope to those who would like to reverse the ongoing trends of population change and emphasize the need for spatial planning to cope with the changes. This is an approach which currently does not exist in practice in Lithuania.

Description: This study presents the analysis of Akure urban land use change detection from remote imagery perspective. Efforts were made to examine the direction that the continuous expansion of the city tends towards since its inception as a state capital in 1976. Using Aerial Imagery Overlay (AIO), the pattern of land use changes in Akure and its environs were determined. This involves imageries interpolation and overlaying to determine the land use changes, direction, and extent of the expansion. Findings revealed unguided expansion in the growth of the city which affects the pattern of land uses within the city and, by extension, into the adjoining settlements. There were incompatible conversions in land uses and undue encroachment into green areas in the adjoining communities. The study suggests effective zoning strategy on unguided nature of urban development whose effects on land use are very prominent in the study area. Adequate monitoring by the Development Control Department and other stakeholders in urban planning is equally suggested to mitigate the incompatible land use changes in the area.

Description: Shrinking populations have been gaining increasing attention, especially in postsocialist Eastern and Central European countries. While most studies focus on specific cities and regions, much less is known about the spatial dimension of population decline on the national level and the local factors determining spatially uneven population change. This study uses Lithuanian census data from the years 2001 to 2011 to get insight into the geography of population change for the whole country. Lithuania has experienced one of the highest rates of population decline in the world in the last decades. The predictive models show that regional factors have a strong effect on the variation in population change throughout the country but also reveal that sociodemographic and economic area characteristics play a role in the process of decline. Our results give little hope to those who would like to reverse the ongoing trends of population change and emphasize the need for spatial planning to cope with the changes. This is an approach which currently does not exist in practice in Lithuania.

Description: Research on urban heat island (UHI) mitigation has been carried out globally. Several strategies have been proposed or developed to mitigate UHI, including highly reflective (HR) envelopes of buildings, green roofs, urban vegetation, shading, heat sinks, and air-conditioning efficiency. Among these techniques, HR envelopes have been extensively studied as an effective method to mitigate the UHI effect by reducing energy consumption. However, because most of HR materials are diffusive, HR envelopes applied to vertical surfaces can reflect both onto roads and nearby buildings. Additionally, HR roofs cannot reflect all incoming solar radiation to the sky if there are high buildings around it. Thus, HR materials applied as building envelopes have a limited effect against the solar contribution to the UHI. In order to solve this problem, retroreflective (RR) materials, which reflect the solar radiation back towards the source, have been studied and developed to be applied as building envelopes instead of HR materials. This paper summarizes several previous researches on HR envelopes and cool roofs and summarizes several current researches on RR materials. The potential for application of RR envelopes in cities is proposed with consideration of economic and environmental factors.

Description: We present a comparative study of computational methods for estimation of ionospheric scintillation indices. First, we review the conventional approaches based on Fourier transformation and low-pass/high-pass frequency filtration. Next, we introduce a novel method based on nonparametric local regression with bias Corrected Akaike Information Criteria (AICC). All methods are then applied to data from the Norwegian Regional Ionospheric Scintillation Network (NRISN), which is shown to be dominated by phase scintillation and not amplitude scintillation. We find that all methods provide highly correlated results, demonstrating the validity of the new approach to this problem. All methods are shown to be very sensitive to filter characteristics and the averaging interval. Finally, we find that the new method is more robust to discontinuous phase observations than conventional methods.

Description: This paper evaluates the independent effect of the spatial proximity of green urban areas upon the individual subjective well-being of the Milan population (Italy). The methodology is based on a survey undertaken in 2010 using a sample of 1,000 of Milan citizens. Univariate and multivariate analyses and GIS localization have been employed in order to rank the major individual well-being determinants and the relationship between citizens and urban green areas. Results show that the residential proximity of citizens to urban green areas seems to have little bearing on individual subjective well-being.

Description: An attitude estimation algorithm is developed using an adaptive extended Kalman filter for low-cost microelectromechanical-system (MEMS) triaxial accelerometers and gyroscopes, that is, inertial measurement units (IMUs). Although these MEMS sensors are relatively cheap, they give more inaccurate measurements than conventional high-quality gyroscopes and accelerometers. To be able to use these low-cost MEMS sensors with precision in all situations, a novel attitude estimation algorithm is proposed for fusing triaxial gyroscope and accelerometer measurements. An extended Kalman filter is implemented to estimate attitude in direction cosine matrix (DCM) formation and to calibrate gyroscope biases online. We use a variable measurement covariance for acceleration measurements to ensure robustness against temporary nongravitational accelerations, which usually induce errors when estimating attitude with ordinary algorithms. The proposed algorithm enables accurate gyroscope online calibration by using only a triaxial gyroscope and accelerometer. It outperforms comparable state-of-the-art algorithms in those cases when there are either biases in the gyroscope measurements or large temporary nongravitational accelerations present. A low-cost, temperature-based calibration method is also discussed for initially calibrating gyroscope and acceleration sensors. An open source implementation of the algorithm is also available.

Description: Multipath propagation is one of the major sources of error in GPS measurements. In this research, a ray-tracing technique is proposed to study the frequency domain characteristics of multipath propagation. The Doppler frequency difference, also known as multipath phase rate and fading frequency, between direct (line-of-sight, LOS) and reflected (non-line-of-sight, NLOS) signals is studied as a function of satellite elevation and azimuth, as well as distance between the reflector and the static receiver. The accuracy of the method is verified with measured Doppler differences from real data collected in a downtown environment. The use of ray-tracing derived predicted Doppler differences in a receiver, as a means of alleviating the multipath induced errors in the measurement, is presented and discussed.

Description: Automatic Dependent Surveillance-Broadcast (ADS-B) is an air traffic surveillance technology in which aircraft transmit position and identification. The development of space-based ADS-B will allow precise control of aircraft in areas that are not covered by radar, such as oceanic regions and high latitudes. The Royal Military College of Canada has developed a spaceborne ADS-B receiver scheduled to fly on the Canadian Advanced Nanospace eXperiment-7 (CanX-7) satellite. The payload is planned to collect data over the North Atlantic region, which will then be compared to truth data provided by air traffic services. A model was created to determine power levels arriving at the satellite to provide confidence in the ADS-B receiver and antenna proposed for CanX-7. The model takes into account neutral atmosphere and ionospheric effects, aircraft-satellite geometry, and antenna radiation patterns. A simulation was run by inserting real aircraft data from the North Atlantic Track System into the model and placing the satellite at altitudes of 400, 600, and 800 km. Results of the simulation indicate that power received at the satellite, ranging between −98.5 dBm and −103 dBm for the selected altitudes, will be sufficient to successfully conduct the mission.

Description: This study was conducted with the objective of finding the perceivable effect of figures and backgrounds on residential streetscapes and their connections in visual complexity. The visual complexity depends on the extent of information a viewer can observe from a visible area. The information includes a number of visual elements along the streetscapes and their diversity and interconnections. The aim of this research was to analyze the structural hierarchical visual complexity of the streetscapes, caused by varied spatial arrangement and numerous spatial connections of the perceivable visual elements. The visual elements of 60 residential streetscapes were classified into figures and backgrounds using human perception of 20 subjects. The identified figures and backgrounds were arranged in a taxonomic diagram representing their connections. These taxonomic diagrams reflect the structural hierarchical visual complexity. Finally, taxonomic entropy was applied to statistically analyze the structural hierarchical visual complexity. When the taxonomic diagram is vertically and horizontally lengthy and the arrangement of the elements of taxonomic diagram is irregular, the complexity increases depicting a large number of figures whose spatial connections impart a high visual complexity to the streetscapes.

Description: This paper evaluates the independent effect of the spatial proximity of green urban areas upon the individual subjective well-being of the Milan population (Italy). The methodology is based on a survey undertaken in 2010 using a sample of 1,000 of Milan citizens. Univariate and multivariate analyses and GIS localization have been employed in order to rank the major individual well-being determinants and the relationship between citizens and urban green areas. Results show that the residential proximity of citizens to urban green areas seems to have little bearing on individual subjective well-being.

Description: Comparison of high-performance time scales generated by atomic clocks in laboratories of time and frequency metrology is usually performed by means of the Common View method. Laboratories are equipped with specialized GNSS receivers which measure the difference between a local time scale and a time scale of the selected satellite. Every receiver generates log files in CGGTTS data format to record measured differences. In order to calculate time differences recorded by two receivers, it is necessary to obtain these logs from both receivers and process them. This paper deals with automation and speeding up of these processes.

Description: Following the Great Recession (2007–2009), growth in multiunit housing starts has been exceptionally strong and sustained. In this study, we examine empirical evidence for three possible explanations, namely, the passage of Baby Boomers into senior years, the depressed economic conditions, and rising preference of recent birth cohorts for residing in urban cores. Applying Age-Period-Cohort analysis to census data on multiunit housing occupancy from 1970 to 2010, we find evidence to support the explanations that a sharp increase in demand from Millennials drawn to urban cores and retiring Baby Boomers are contributing to the growth in multiunit housing starts. The results provide weak evidence of a negative relationship between depressed economic conditions and demand for multiunit housing starts. Over the long term, demand for multiunit housing can be expected to moderate as a result of the projected aging of the population.

Description: Performance of Global Navigation Satellite System (GNSS) positioning in urban environments is hindered by poor satellite availability because there are many man-made and natural objects in urban environments that obstruct satellite signals. To evaluate the availability of GNSS in cities, this paper presents a software simulation of GNSS availability in urban areas using a panoramic image dataset from Google Street View. Photogrammetric image processing techniques are applied to reconstruct fisheye sky view images and detect signal obstacles. Two comparisons of the results from the simulation and real world observation in Bangkok and Tokyo are also presented and discussed for accuracy assessment.

Description: This study was undertaken to obtain direct and useful data that support biodiversity awareness and management in two cities of Niger. 800 questionnaires were administrated to the populations of Niamey and Maradi. The results show that 99% of respondents are aware of the importance of biodiversity in urban areas. They assign multiple roles to it; however, climatic and managerial reasons explain why plants are most preferred to animals in these cities. Furthermore, shade and fruits are the criteria for plant species selection, and that explains the abundance of Azadirachta indica A. Juss. and Mangifera indica L. Even though plants are preferred to animals in houses, 47% of the respondents practice animal husbandry. Most of the animals are left wandering with risks of destruction of green areas, road unsafety, and zoonotic contamination. The results of this study also showed the ignorance of 55% of the respondents about the presence of wildlife in urban areas. The proliferation of cockroaches and rats could be an indication of insanitary conditions that are faced in some areas of the cities as mentioned by 81% of the respondents. This study shows the importance of local knowledge in the identification process of urban problems.

Description: Measurements of delays of the signals radiated by transmitters of navigational satellites allow us to obtain the total electron content (TEC). In addition, measurements of TEC allow solving problems such as development of local, regional, and global models of TEC and correction of ionospheric delay for increasing accuracy of positioning. Now, it is possible to set the task of calculation of critical frequency foF2 with the use of experimental values of TEC in a global scale. For this purpose it is necessary to know an equivalent slab thickness of the ionosphere which is a coefficient of proportionality between TEC and a maximum density of the ionosphere. The present paper is devoted to the analysis of investigation and utilization of this parameter. It is shown that (1) existing models of τ are not empirical and not always can provide an adequate accuracy of foF2 calculation, (2) experimental median (med) provides much larger accuracy of foF2 calculation than the empirical model and variations from day to day and allows filling gaps in the ionosonde data, and (3) it is possible to use a hyperbolic approximation and coefficient for development of a global model of .

Description: The lower-class segment of the population of the developing nations often fails to form meaningful social relations and remain disengaged from essential social institutions. The research examines those people who live in refugee-camp and sullied slum of Dhaka city and inspect how much they are socially isolated. Certain characteristics, taken as indicators to test the level of social isolation, indicate that a large segment of camp and slum dwellers are feeling isolated. However, the evidence shows no differences in the predicted direction with respect to the objective demographic variables; nonetheless, a pattern of perceived social isolation was found from the survey data.

Description: Relying on nationally representative data from the most recent wave of the National Survey of Black Americans (NSBA), the current study examines how past and present neighborhood racial composition is associated with feelings of closeness toward black Americans, black Africans, and black West Indians. In addition, this research tests whether race-based socialization messages received from caregivers or religious socialization messages explain this relationship among a sample from the adult black US population. The findings show that past neighborhood composition is associated with present feelings of closeness toward black Americans and black West Indians but are not associated with close feelings toward black Africans. Current neighborhood racial composition is not associated with feelings of closeness toward any of the groups. Racial socialization messages are associated with closeness towards them all but are found to be largely a function of having a two-parent family during childhood. Religious socialization is also associated with intraracial feelings of closeness. Results suggest that neighborhood racial composition is important to help facilitate positive feelings toward others who share the same race but a different ethnicity.

Description: We test whether ethnic diversity in Dutch neighbourhoods and municipalities drives down associational involvement and build on earlier research in two important ways. First, we explicitly take into account the ethnic composition of local voluntary associations, distinguishing involvement in bonding (only in-group members) and bridging (with out-group members) associations. Second, we aim to explain relationships between ethnic diversity and associational involvement, testing two competing sets of predictions derived from conflict and contact theories. Using data from the Netherlands Longitudinal Lifecourse Study (2013), ethnic diversity turns out to hardly affect associational involvement negatively. Only for leisure associations, living in ethnically more diverse municipalities substantially decreases the likelihood to be involved in bonding associations, whereas higher levels of neighbourhood ethnic diversity increase the likelihood to be involved in bridging associations. Moreover, ethnic diversity indirectly affects associational involvement via interethnic contact. Higher levels of ethnic diversity increase interethnic contact which, in turn, is negatively related to involvement in bonding associations. Whereas higher levels of ethnic diversity in neighbourhoods increase perceptions of ethnic threat, these perceptions decrease with higher levels of ethnic diversity in the municipality. Perceptions of ethnic threat do not, however, affect associational involvement. Our results shed more light on the direct and indirect relationships between ethnic diversity and bonding and bridging associational involvement.

Description: This paper demonstrates that automatic selection of the right interpolation/smoothing method in a GNSS-based network real-time kinematic (NRTK) interpolation segment can improve the accuracy of the rover position estimates and also the processing time in the NRTK processing center. The methods discussed and investigated are inverse distance weighting (IDW); bilinear and bicubic spline interpolation; kriging interpolation; thin-plate splines; and numerical approximation methods for spatial processes. The methods are implemented and tested using GNSS data from reference stations in the Norwegian network RTK service called CPOS. Data sets with an average baseline between reference stations of 60–70 km were selected. 12 prediction locations were used to analyze the performance of the interpolation methods by computing and comparing different measures of the goodness of fit such as the root mean square error (RMSE), mean square error, and mean absolute error, and also the computation time was compared. Results of the tests show that ordinary kriging with the Matérn covariance function clearly provides the best results. The thin-plate spline provides the second best results of the methods selected and with the test data used.

Description: This paper investigates the accuracy of six measures of housing cost differences among US metropolitan areas. Using Census data from 177 metropolitan areas, it tests the measures in two ways. First, it tests the ability of changes in the measures to predict changes in the shelter component of the metropolitan CPI from 1990 to 2000. Second, it tests the ability of the measures themselves to predict a proxy in 2000. A measure based on Fair Market Rents calculated by HUD placed second on the first test but did badly on the second. The housing component of the ACCRA index, a living cost measure frequently used by researchers, performed poorly on both tests. The top performer on both tests was a measure based on the average rent per room for a metropolitan area’s dwellings. Researchers wishing to control for living cost differences among places should consider including it in their living cost index.

Description: This paper deals with the design of a fault detection and isolation (FDI) system for an intelligent vehicle, a vehicle equipped with advanced driver assistance system (ADAS). The ADASs are outfitted with sensors for acquiring various information about the vehicle and its surroundings. Since these sensors are sensitive to faults, an efficient FDI system should be developed. The designed FDI system is comprised of three parts: a detection part, a decision part, and a fault management part. The detection part applies a generalized observer scheme (GOS). In the GOS, there is bank of extended Kalman filters (EKFs), each excited by all except one sensor measurement. The residual generated from the measurement update of each EKF is therefore sensitive to all sensor faults but one. This way, the fault sensitivity pattern of the residual makes it possible to detect a fault and locate the faulty sensor. The designed FDI system has been implemented and tested off-line with actual experiment data. Good results have been obtained with diagnosing individual sensor faults and outputting fault-free vehicle states.

Description: Auckland is New Zealand’s largest city which also has the largest concentration of creative sector employment and businesses in the country. This study examines the spatial logic of firms in the design creative subsector in inner Auckland to gain better understanding of the ways in which place, space, and built form determine location choices. Firms’ attributes are also analysed with the aim of ascertaining whether firms with shared characteristics have similar spatial behaviour. Despite a high degree of spatial clustering, the unequal distribution of firms across inner Auckland suggests that some areas, such as Parnell, are favoured more than others. Parnell’s unique heritage built environment was identified as a location factor that has appealed to architects, designers, and advertisers and has contributed to the formation of the area’s creative clusters. The quality of Parnell’s built environment was associated with place reputation and image branding which was an important part of creating firm’s identity. A central location and the attractiveness of an amenities-rich local environment also played a role in the decision-making process. Furthermore, the results also suggest that firms that possess common characteristics have similar spatial logic and make similar location choices.

Description: Direct experiences with nature in childhood are essential for enhancing psychological and physical development in children. However, researches on childhood nature-related experiences and their effects are largely biased toward more developed Western countries. In this study, we created a questionnaire on childhood experiences with nature and surveyed 357 adults (〉20 years old) around Kuala Lumpur, the capital of Malaysia, to determine whether younger generations had fewer nature-based experiences than older generations and whether people who grew up in urban areas had fewer experiences than those who grew up in rural areas. We found that playing in rivers or waterfalls and collecting and eating tropical fruits were the most common nature-related activities experienced in childhood. There was a minimal decline in nature-related experiences among generations. However, people who grew up in rural areas had more nature-related experiences than those who grew up in urban areas. The loss of nature areas and increase in population density may accelerate the decline in nature-related experiences in urban areas. Therefore, efforts to create urban parks and other public spaces for reconnecting urban children to nature will become increasingly important for urban planning and environmental education in tropical developing countries such as Malaysia.

Description: Nowadays, a Global Navigation Satellite System (GNSS) unit is embedded in nearly every smartphone. This unit allows a smartphone to detect the user’s location and motion, and it makes functions, such as navigation, tracking, and compass applications, available to the user. Therefore, the GNSS unit has become one of the most important features in modern smartphones. However, because most smartphones incorporate relatively low-cost GNSS chips, their localization accuracy varies depending on the number of accessible GNSS satellites, and it is highly dependent on environmental factors that cause interference such as forests and buildings. This research evaluated the performance of the GNSS units inside two different models of smartphones in determining pedestrian locations in different environments. The results indicate that the overall performances of the two devices were related directly to the environment, type of smartphone/GNSS chipset, and the application used to collect the information.

Description: Relying on nationally representative data from the most recent wave of the National Survey of Black Americans (NSBA), the current study examines how past and present neighborhood racial composition is associated with feelings of closeness toward black Americans, black Africans, and black West Indians. In addition, this research tests whether race-based socialization messages received from caregivers or religious socialization messages explain this relationship among a sample from the adult black US population. The findings show that past neighborhood composition is associated with present feelings of closeness toward black Americans and black West Indians but are not associated with close feelings toward black Africans. Current neighborhood racial composition is not associated with feelings of closeness toward any of the groups. Racial socialization messages are associated with closeness towards them all but are found to be largely a function of having a two-parent family during childhood. Religious socialization is also associated with intraracial feelings of closeness. Results suggest that neighborhood racial composition is important to help facilitate positive feelings toward others who share the same race but a different ethnicity.

Description: Comparison of high-performance time scales generated by atomic clocks in laboratories of time and frequency metrology is usually performed by means of the Common View method. Laboratories are equipped with specialized GNSS receivers which measure the difference between a local time scale and a time scale of the selected satellite. Every receiver generates log files in CGGTTS data format to record measured differences. In order to calculate time differences recorded by two receivers, it is necessary to obtain these logs from both receivers and process them. This paper deals with automation and speeding up of these processes.

Description: This study was undertaken to obtain direct and useful data that support biodiversity awareness and management in two cities of Niger. 800 questionnaires were administrated to the populations of Niamey and Maradi. The results show that 99% of respondents are aware of the importance of biodiversity in urban areas. They assign multiple roles to it; however, climatic and managerial reasons explain why plants are most preferred to animals in these cities. Furthermore, shade and fruits are the criteria for plant species selection, and that explains the abundance of Azadirachta indica A. Juss. and Mangifera indica L. Even though plants are preferred to animals in houses, 47% of the respondents practice animal husbandry. Most of the animals are left wandering with risks of destruction of green areas, road unsafety, and zoonotic contamination. The results of this study also showed the ignorance of 55% of the respondents about the presence of wildlife in urban areas. The proliferation of cockroaches and rats could be an indication of insanitary conditions that are faced in some areas of the cities as mentioned by 81% of the respondents. This study shows the importance of local knowledge in the identification process of urban problems.

Description: Nowadays, a Global Navigation Satellite System (GNSS) unit is embedded in nearly every smartphone. This unit allows a smartphone to detect the user’s location and motion, and it makes functions, such as navigation, tracking, and compass applications, available to the user. Therefore, the GNSS unit has become one of the most important features in modern smartphones. However, because most smartphones incorporate relatively low-cost GNSS chips, their localization accuracy varies depending on the number of accessible GNSS satellites, and it is highly dependent on environmental factors that cause interference such as forests and buildings. This research evaluated the performance of the GNSS units inside two different models of smartphones in determining pedestrian locations in different environments. The results indicate that the overall performances of the two devices were related directly to the environment, type of smartphone/GNSS chipset, and the application used to collect the information.

Description: High frequency (HF) radar installations are becoming essential components of operational real-time marine monitoring systems. The underlying technology is being further enhanced to fully exploit the potential of mapping sea surface currents and wave fields over wide areas with high spatial and temporal resolution, even in adverse meteo-marine conditions. Data applications are opening to many different sectors, reaching out beyond research and monitoring, targeting downstream services in support to key national and regional stakeholders. In the CALYPSO project, the HF radar system composed of CODAR SeaSonde stations installed in the Malta Channel is specifically serving to assist in the response against marine oil spills and to support search and rescue at sea. One key drawback concerns the sporadic inconsistency in the spatial coverage of radar data which is dictated by the sea state as well as by interference from unknown sources that may be competing with transmissions in the same frequency band. This work investigates the use of Machine Learning techniques to fill in missing data in a high resolution grid. Past radar data and wind vectors obtained from satellites are used to predict missing information and provide a more consistent dataset.

Description: Performance of Global Navigation Satellite System (GNSS) positioning in urban environments is hindered by poor satellite availability because there are many man-made and natural objects in urban environments that obstruct satellite signals. To evaluate the availability of GNSS in cities, this paper presents a software simulation of GNSS availability in urban areas using a panoramic image dataset from Google Street View. Photogrammetric image processing techniques are applied to reconstruct fisheye sky view images and detect signal obstacles. Two comparisons of the results from the simulation and real world observation in Bangkok and Tokyo are also presented and discussed for accuracy assessment.

Description: Measurements of delays of the signals radiated by transmitters of navigational satellites allow us to obtain the total electron content (TEC). In addition, measurements of TEC allow solving problems such as development of local, regional, and global models of TEC and correction of ionospheric delay for increasing accuracy of positioning. Now, it is possible to set the task of calculation of critical frequency foF2 with the use of experimental values of TEC in a global scale. For this purpose it is necessary to know an equivalent slab thickness of the ionosphere which is a coefficient of proportionality between TEC and a maximum density of the ionosphere. The present paper is devoted to the analysis of investigation and utilization of this parameter. It is shown that (1) existing models of τ are not empirical and not always can provide an adequate accuracy of foF2 calculation, (2) experimental median (med) provides much larger accuracy of foF2 calculation than the empirical model and variations from day to day and allows filling gaps in the ionosonde data, and (3) it is possible to use a hyperbolic approximation and coefficient for development of a global model of .

Description: Auckland is New Zealand’s largest city which also has the largest concentration of creative sector employment and businesses in the country. This study examines the spatial logic of firms in the design creative subsector in inner Auckland to gain better understanding of the ways in which place, space, and built form determine location choices. Firms’ attributes are also analysed with the aim of ascertaining whether firms with shared characteristics have similar spatial behaviour. Despite a high degree of spatial clustering, the unequal distribution of firms across inner Auckland suggests that some areas, such as Parnell, are favoured more than others. Parnell’s unique heritage built environment was identified as a location factor that has appealed to architects, designers, and advertisers and has contributed to the formation of the area’s creative clusters. The quality of Parnell’s built environment was associated with place reputation and image branding which was an important part of creating firm’s identity. A central location and the attractiveness of an amenities-rich local environment also played a role in the decision-making process. Furthermore, the results also suggest that firms that possess common characteristics have similar spatial logic and make similar location choices.

Description: Direct experiences with nature in childhood are essential for enhancing psychological and physical development in children. However, researches on childhood nature-related experiences and their effects are largely biased toward more developed Western countries. In this study, we created a questionnaire on childhood experiences with nature and surveyed 357 adults (〉20 years old) around Kuala Lumpur, the capital of Malaysia, to determine whether younger generations had fewer nature-based experiences than older generations and whether people who grew up in urban areas had fewer experiences than those who grew up in rural areas. We found that playing in rivers or waterfalls and collecting and eating tropical fruits were the most common nature-related activities experienced in childhood. There was a minimal decline in nature-related experiences among generations. However, people who grew up in rural areas had more nature-related experiences than those who grew up in urban areas. The loss of nature areas and increase in population density may accelerate the decline in nature-related experiences in urban areas. Therefore, efforts to create urban parks and other public spaces for reconnecting urban children to nature will become increasingly important for urban planning and environmental education in tropical developing countries such as Malaysia.

Description: Following the Great Recession (2007–2009), growth in multiunit housing starts has been exceptionally strong and sustained. In this study, we examine empirical evidence for three possible explanations, namely, the passage of Baby Boomers into senior years, the depressed economic conditions, and rising preference of recent birth cohorts for residing in urban cores. Applying Age-Period-Cohort analysis to census data on multiunit housing occupancy from 1970 to 2010, we find evidence to support the explanations that a sharp increase in demand from Millennials drawn to urban cores and retiring Baby Boomers are contributing to the growth in multiunit housing starts. The results provide weak evidence of a negative relationship between depressed economic conditions and demand for multiunit housing starts. Over the long term, demand for multiunit housing can be expected to moderate as a result of the projected aging of the population.

Description: This paper seeks to examine the ethnoreligious urban violence and residential mobility in the city of Kaduna with a view to make recommendations towards ameliorating its effects by evaluating the causal factors fueling the crisis and examining the pattern and direction of the residential mobility in the city. The sources of data were both primary and secondary. The sampling technique used was purposive and random sampling from two residential districts from both the northern and southern parts of the city. A total of 1,000 questionnaires were administered within the study areas and 900 questionnaires were collected. Face-to-face interviews were conducted with major stakeholders from the two parts. The data obtained were analysed using thematic and content analysis for the qualitative data whilst the quantitative data were analysed using simple percentages. The results revealed that the factors causing the ethnoreligious urban violence and residential mobility are unemployment, social institutional breakdown, politics, and colonial impact and the pattern/direction of the residential mobility in the city of Kaduna show a clear polarization along religious lines based reactive residential mobility between the two parts of the city. Based on these results recommendations were made to assist the academia, practitioners, and policy makers.

Description: Violence by young people is one of the most visible forms of social disorder in urban settlements. This study assesses the causes and consequences of youth violence in the Kumasi metropolis. The study design was a nonexperimental cross-sectional survey. A mixed method approach facilitated the random sampling of 71 young people in the Kumasi metropolis through a stratified procedure between December 2014 and November 2015. Ten (10) participants were purposively selected and enrolled in a focus group discussion. Descriptive statistics formed the basis for the analysis. This was supported with a matched discourse analysis of the emerging themes. More than half of the youth (39, 54.9%) demonstrated history of ever engaging in violence in the past one year of whom 24 (61.5%) were without formal education. The frequency of the violence perpetuation ranged from daily engagement (3, 4%) to weekly engagement in violence (12, 17%). Principally, the categories of youth violence were manifested in noise making, rape, murder, stealing, drug addiction, obscene gestures, robbery, sexual abuse, and embarrassment. Peer pressure and street survival coping approaches emerged as the pivotal factors that induced youth violence. Addressing youth violence requires an integrative framework that incorporates youth perspectives, government, chiefs, and nongovernmental organizations in Ghana, and religious bodies.

Description: This paper presents an acoustic indoor localization system for commercial smart phones that emit high pitched acoustic signals beyond the audible range. The acoustic signals with an identifier code modulated on the signal are detected by self-built receivers which are placed at the ceiling or on walls in a room. The receivers are connected in a Wi-Fi network, such that they synchronize their clocks and exchange the time differences of arrival (TDoA) of the received chirps. The location of the smart phone is calculated by TDoA multilateration. The precise time measuring of sound enables high precision localization in indoor areas. Our approach enables applications that require high accuracy, such as finding products in a supermarket or guiding blind people through complicated buildings. We have evaluated our system in real-world experiments using different algorithms for calibration-free localization and different types of sound signals. The adaptive GOGO-CFAR threshold enables a detection of 48% of the chirp pulses even at a distance of 30 m. In addition, we have compared the trajectory of a pedestrian carrying a smart phone to reference positions of an optic system. Consequently, the localization error is observed to be less than 30 cm.

Description: An extensive body of literature suggests that physical environment, physical activity, and socioeconomic status (SES) are intrinsically linked to each other and to weight related health problems. In this study, the role of objective and perceived pedestrian environment characteristics (microscale measures) was explored in relation to people’s recreational walking patterns in two neighborhoods with opposite SES. A total of 441 street segments were assessed and a total of 133 questionnaires were conducted. The findings suggest that recreational walking can take place beyond a neighborhood’s suggested SES when objective and especially perceived microscale characteristics (pedestrian environment) are favorable.

Description: Examining the performance of the GNSS PLL, this paper presents novel results describing the statistical properties of four popular phase estimators under both strong- and weak-signal conditions when subject to thermal noise, deterministic dynamics, and typical pedestrian motion. Design routines are developed which employ these results to enhance weak-signal performance of the PLL in terms of transient response, steady-state errors, and cycle-slips. By examining both single and data-pilot signals, it is shown that appropriate design and tuning of the PLL can significantly enhance tracking performance, in particular when used for pedestrian applications.

Description: We present a comparative study of computational methods for estimation of ionospheric scintillation indices. First, we review the conventional approaches based on Fourier transformation and low-pass/high-pass frequency filtration. Next, we introduce a novel method based on nonparametric local regression with bias Corrected Akaike Information Criteria (AICC). All methods are then applied to data from the Norwegian Regional Ionospheric Scintillation Network (NRISN), which is shown to be dominated by phase scintillation and not amplitude scintillation. We find that all methods provide highly correlated results, demonstrating the validity of the new approach to this problem. All methods are shown to be very sensitive to filter characteristics and the averaging interval. Finally, we find that the new method is more robust to discontinuous phase observations than conventional methods.

Description: The knowledge of environmental maps (i.e., map-awareness) can appreciably improve the accuracy of optimal methods for position estimation in indoor scenarios. This improvement, however, is achieved at the price of a significant complexity increase with respect to the case of map-unawareness, specially for large maps. This is mainly due to the fact that optimal map-aware estimation algorithms require integrating highly nonlinear functions or solving nonlinear and nonconvex constrained optimization problems. In this paper, various techniques for reducing the complexity of such estimators are developed. In particular, two novel strategies for restricting the search domain of map-aware position estimators are developed and the exploitation of state-of-the-art numerical integration and optimization methods is investigated; this leads to the development of a new family of suboptimal map-aware localization algorithms. Our numerical and experimental results evidence that the accuracy of these algorithms is very close to that offered by their optimal counterparts, despite their significantly lower computational complexity.

Description: Performance of Global Navigation Satellite System (GNSS) positioning in urban environments is hindered by poor satellite availability because there are many man-made and natural objects in urban environments that obstruct satellite signals. To evaluate the availability of GNSS in cities, this paper presents a software simulation of GNSS availability in urban areas using a panoramic image dataset from Google Street View. Photogrammetric image processing techniques are applied to reconstruct fisheye sky view images and detect signal obstacles. Two comparisons of the results from the simulation and real world observation in Bangkok and Tokyo are also presented and discussed for accuracy assessment.

Description: This paper presents an acoustic indoor localization system for commercial smart phones that emit high pitched acoustic signals beyond the audible range. The acoustic signals with an identifier code modulated on the signal are detected by self-built receivers which are placed at the ceiling or on walls in a room. The receivers are connected in a Wi-Fi network, such that they synchronize their clocks and exchange the time differences of arrival (TDoA) of the received chirps. The location of the smart phone is calculated by TDoA multilateration. The precise time measuring of sound enables high precision localization in indoor areas. Our approach enables applications that require high accuracy, such as finding products in a supermarket or guiding blind people through complicated buildings. We have evaluated our system in real-world experiments using different algorithms for calibration-free localization and different types of sound signals. The adaptive GOGO-CFAR threshold enables a detection of 48% of the chirp pulses even at a distance of 30 m. In addition, we have compared the trajectory of a pedestrian carrying a smart phone to reference positions of an optic system. Consequently, the localization error is observed to be less than 30 cm.

Description: Automatic Dependent Surveillance-Broadcast (ADS-B) is an air traffic surveillance technology in which aircraft transmit position and identification. The development of space-based ADS-B will allow precise control of aircraft in areas that are not covered by radar, such as oceanic regions and high latitudes. The Royal Military College of Canada has developed a spaceborne ADS-B receiver scheduled to fly on the Canadian Advanced Nanospace eXperiment-7 (CanX-7) satellite. The payload is planned to collect data over the North Atlantic region, which will then be compared to truth data provided by air traffic services. A model was created to determine power levels arriving at the satellite to provide confidence in the ADS-B receiver and antenna proposed for CanX-7. The model takes into account neutral atmosphere and ionospheric effects, aircraft-satellite geometry, and antenna radiation patterns. A simulation was run by inserting real aircraft data from the North Atlantic Track System into the model and placing the satellite at altitudes of 400, 600, and 800 km. Results of the simulation indicate that power received at the satellite, ranging between −98.5 dBm and −103 dBm for the selected altitudes, will be sufficient to successfully conduct the mission.

Description: Multipath propagation is one of the major sources of error in GPS measurements. In this research, a ray-tracing technique is proposed to study the frequency domain characteristics of multipath propagation. The Doppler frequency difference, also known as multipath phase rate and fading frequency, between direct (line-of-sight, LOS) and reflected (non-line-of-sight, NLOS) signals is studied as a function of satellite elevation and azimuth, as well as distance between the reflector and the static receiver. The accuracy of the method is verified with measured Doppler differences from real data collected in a downtown environment. The use of ray-tracing derived predicted Doppler differences in a receiver, as a means of alleviating the multipath induced errors in the measurement, is presented and discussed.

Description: With modern global navigation satellite system (GNSS) signals, the FFT-based parallel code search acquisition must handle the frequent sign transitions due to the data or the secondary code. There is a straightforward solution to this problem, which consists in doubling the length of the FFTs, leading to a significant increase of the complexity. The authors already proposed a method to reduce the complexity without impairing the probability of detection. In particular, this led to a 50% memory reduction for an FPGA implementation. In this paper, the authors propose another approach, namely, the splitting of a large FFT into three or five smaller FFTs, providing better performances and higher flexibility. For an FPGA implementation, compared to the previously proposed approach, at the expense of a slight increase of the logic and multiplier resources, the splitting into three and five allows, respectively, a reduction of 40% and 64% of the memory, and of 25% and 37.5% of the processing time. Moreover, with the splitting into three FFTs, the algorithm is applicable for sampling frequencies up to 24.576 MHz for L5 band signals, against 21.846 MHz with the previously proposed algorithm. The algorithm is applied here to the GPS L5 and Galileo E5a, E5b, and E1 signals.

Description: Direct experiences with nature in childhood are essential for enhancing psychological and physical development in children. However, researches on childhood nature-related experiences and their effects are largely biased toward more developed Western countries. In this study, we created a questionnaire on childhood experiences with nature and surveyed 357 adults (〉20 years old) around Kuala Lumpur, the capital of Malaysia, to determine whether younger generations had fewer nature-based experiences than older generations and whether people who grew up in urban areas had fewer experiences than those who grew up in rural areas. We found that playing in rivers or waterfalls and collecting and eating tropical fruits were the most common nature-related activities experienced in childhood. There was a minimal decline in nature-related experiences among generations. However, people who grew up in rural areas had more nature-related experiences than those who grew up in urban areas. The loss of nature areas and increase in population density may accelerate the decline in nature-related experiences in urban areas. Therefore, efforts to create urban parks and other public spaces for reconnecting urban children to nature will become increasingly important for urban planning and environmental education in tropical developing countries such as Malaysia.

Description: Following the Great Recession (2007–2009), growth in multiunit housing starts has been exceptionally strong and sustained. In this study, we examine empirical evidence for three possible explanations, namely, the passage of Baby Boomers into senior years, the depressed economic conditions, and rising preference of recent birth cohorts for residing in urban cores. Applying Age-Period-Cohort analysis to census data on multiunit housing occupancy from 1970 to 2010, we find evidence to support the explanations that a sharp increase in demand from Millennials drawn to urban cores and retiring Baby Boomers are contributing to the growth in multiunit housing starts. The results provide weak evidence of a negative relationship between depressed economic conditions and demand for multiunit housing starts. Over the long term, demand for multiunit housing can be expected to moderate as a result of the projected aging of the population.

Description: High frequency (HF) radar installations are becoming essential components of operational real-time marine monitoring systems. The underlying technology is being further enhanced to fully exploit the potential of mapping sea surface currents and wave fields over wide areas with high spatial and temporal resolution, even in adverse meteo-marine conditions. Data applications are opening to many different sectors, reaching out beyond research and monitoring, targeting downstream services in support to key national and regional stakeholders. In the CALYPSO project, the HF radar system composed of CODAR SeaSonde stations installed in the Malta Channel is specifically serving to assist in the response against marine oil spills and to support search and rescue at sea. One key drawback concerns the sporadic inconsistency in the spatial coverage of radar data which is dictated by the sea state as well as by interference from unknown sources that may be competing with transmissions in the same frequency band. This work investigates the use of Machine Learning techniques to fill in missing data in a high resolution grid. Past radar data and wind vectors obtained from satellites are used to predict missing information and provide a more consistent dataset.

Description: This paper presents a study of differential AoA (Angle-of-Arrival) based 2D localization method utilizing FM radio signals (88 MHz–108 MHz) as Signals of Opportunity (SOP). Given prior knowledge of the transmitters’ position and signal characteristics, the proposed technique utilizes triangulation to localize receiver’s 2D position. Dual antenna interferometry provides the received signals’ AoA required for triangulation. Reliance on precise knowledge of antenna system’s orientation is removed by utilizing differential Angle of Arrivals (dAoAs). The 2D localization accuracy is improved by utilizing colocated transmitters, a concept proposed in this paper as supertowers. Analysis, simulation, and ground-based experiments have been presented; results showed that when the SNR (Signal-to-Noise Ratio) is higher than 45 dB, the proposed method localizes the receiver’s 2D position with an error of less than 15 m.

Description: Nowadays, a Global Navigation Satellite System (GNSS) unit is embedded in nearly every smartphone. This unit allows a smartphone to detect the user’s location and motion, and it makes functions, such as navigation, tracking, and compass applications, available to the user. Therefore, the GNSS unit has become one of the most important features in modern smartphones. However, because most smartphones incorporate relatively low-cost GNSS chips, their localization accuracy varies depending on the number of accessible GNSS satellites, and it is highly dependent on environmental factors that cause interference such as forests and buildings. This research evaluated the performance of the GNSS units inside two different models of smartphones in determining pedestrian locations in different environments. The results indicate that the overall performances of the two devices were related directly to the environment, type of smartphone/GNSS chipset, and the application used to collect the information.

Description: Comparison of high-performance time scales generated by atomic clocks in laboratories of time and frequency metrology is usually performed by means of the Common View method. Laboratories are equipped with specialized GNSS receivers which measure the difference between a local time scale and a time scale of the selected satellite. Every receiver generates log files in CGGTTS data format to record measured differences. In order to calculate time differences recorded by two receivers, it is necessary to obtain these logs from both receivers and process them. This paper deals with automation and speeding up of these processes.

Description: This paper addresses the development of the simulation of the low-level control system for the underwater remotely operated vehicle Visor3. The 6-DOF mathematical model of Visor3 is presented using two coordinated systems: Earth-fixed and body-fixed frames. The navigation, guidance, and control (NGC) structure is divided into three layers: the high level or the mission planner; the mid-level or the path planner; and the low level formed by the navigation and control systems. The nonlinear model-based observer is developed using the extended Kalman filter (EKF) which uses the linearization of the model to estimate the current state. The behavior of the observer is verified through simulations using Simulink®. An experiment was conducted with a trajectory that describes changes in the and and yaw components. To accomplish this task, two algorithms are compared: a multiloop PID and PID with gravity compensation. These controllers and the nonlinear observer are tested using the 6-DOF mathematical model of Visor3. The control and navigation systems are a fundamental part of the low-level control system that will allow Visor3’s operators to take advantage of more advanced vehicle’s capabilities during inspection tasks of port facilities, hydroelectric dams, and oceanographic research.

Description: An attitude estimation algorithm is developed using an adaptive extended Kalman filter for low-cost microelectromechanical-system (MEMS) triaxial accelerometers and gyroscopes, that is, inertial measurement units (IMUs). Although these MEMS sensors are relatively cheap, they give more inaccurate measurements than conventional high-quality gyroscopes and accelerometers. To be able to use these low-cost MEMS sensors with precision in all situations, a novel attitude estimation algorithm is proposed for fusing triaxial gyroscope and accelerometer measurements. An extended Kalman filter is implemented to estimate attitude in direction cosine matrix (DCM) formation and to calibrate gyroscope biases online. We use a variable measurement covariance for acceleration measurements to ensure robustness against temporary nongravitational accelerations, which usually induce errors when estimating attitude with ordinary algorithms. The proposed algorithm enables accurate gyroscope online calibration by using only a triaxial gyroscope and accelerometer. It outperforms comparable state-of-the-art algorithms in those cases when there are either biases in the gyroscope measurements or large temporary nongravitational accelerations present. A low-cost, temperature-based calibration method is also discussed for initially calibrating gyroscope and acceleration sensors. An open source implementation of the algorithm is also available.

Description: Measurements of delays of the signals radiated by transmitters of navigational satellites allow us to obtain the total electron content (TEC). In addition, measurements of TEC allow solving problems such as development of local, regional, and global models of TEC and correction of ionospheric delay for increasing accuracy of positioning. Now, it is possible to set the task of calculation of critical frequency foF2 with the use of experimental values of TEC in a global scale. For this purpose it is necessary to know an equivalent slab thickness of the ionosphere which is a coefficient of proportionality between TEC and a maximum density of the ionosphere. The present paper is devoted to the analysis of investigation and utilization of this parameter. It is shown that (1) existing models of τ are not empirical and not always can provide an adequate accuracy of foF2 calculation, (2) experimental median (med) provides much larger accuracy of foF2 calculation than the empirical model and variations from day to day and allows filling gaps in the ionosonde data, and (3) it is possible to use a hyperbolic approximation and coefficient for development of a global model of .

Description: Auckland is New Zealand’s largest city which also has the largest concentration of creative sector employment and businesses in the country. This study examines the spatial logic of firms in the design creative subsector in inner Auckland to gain better understanding of the ways in which place, space, and built form determine location choices. Firms’ attributes are also analysed with the aim of ascertaining whether firms with shared characteristics have similar spatial behaviour. Despite a high degree of spatial clustering, the unequal distribution of firms across inner Auckland suggests that some areas, such as Parnell, are favoured more than others. Parnell’s unique heritage built environment was identified as a location factor that has appealed to architects, designers, and advertisers and has contributed to the formation of the area’s creative clusters. The quality of Parnell’s built environment was associated with place reputation and image branding which was an important part of creating firm’s identity. A central location and the attractiveness of an amenities-rich local environment also played a role in the decision-making process. Furthermore, the results also suggest that firms that possess common characteristics have similar spatial logic and make similar location choices.

Description: This study presents the analysis of Akure urban land use change detection from remote imagery perspective. Efforts were made to examine the direction that the continuous expansion of the city tends towards since its inception as a state capital in 1976. Using Aerial Imagery Overlay (AIO), the pattern of land use changes in Akure and its environs were determined. This involves imageries interpolation and overlaying to determine the land use changes, direction, and extent of the expansion. Findings revealed unguided expansion in the growth of the city which affects the pattern of land uses within the city and, by extension, into the adjoining settlements. There were incompatible conversions in land uses and undue encroachment into green areas in the adjoining communities. The study suggests effective zoning strategy on unguided nature of urban development whose effects on land use are very prominent in the study area. Adequate monitoring by the Development Control Department and other stakeholders in urban planning is equally suggested to mitigate the incompatible land use changes in the area.

Description: Research on urban heat island (UHI) mitigation has been carried out globally. Several strategies have been proposed or developed to mitigate UHI, including highly reflective (HR) envelopes of buildings, green roofs, urban vegetation, shading, heat sinks, and air-conditioning efficiency. Among these techniques, HR envelopes have been extensively studied as an effective method to mitigate the UHI effect by reducing energy consumption. However, because most of HR materials are diffusive, HR envelopes applied to vertical surfaces can reflect both onto roads and nearby buildings. Additionally, HR roofs cannot reflect all incoming solar radiation to the sky if there are high buildings around it. Thus, HR materials applied as building envelopes have a limited effect against the solar contribution to the UHI. In order to solve this problem, retroreflective (RR) materials, which reflect the solar radiation back towards the source, have been studied and developed to be applied as building envelopes instead of HR materials. This paper summarizes several previous researches on HR envelopes and cool roofs and summarizes several current researches on RR materials. The potential for application of RR envelopes in cities is proposed with consideration of economic and environmental factors.

Description: Shrinking populations have been gaining increasing attention, especially in postsocialist Eastern and Central European countries. While most studies focus on specific cities and regions, much less is known about the spatial dimension of population decline on the national level and the local factors determining spatially uneven population change. This study uses Lithuanian census data from the years 2001 to 2011 to get insight into the geography of population change for the whole country. Lithuania has experienced one of the highest rates of population decline in the world in the last decades. The predictive models show that regional factors have a strong effect on the variation in population change throughout the country but also reveal that sociodemographic and economic area characteristics play a role in the process of decline. Our results give little hope to those who would like to reverse the ongoing trends of population change and emphasize the need for spatial planning to cope with the changes. This is an approach which currently does not exist in practice in Lithuania.

Description: This study was undertaken to obtain direct and useful data that support biodiversity awareness and management in two cities of Niger. 800 questionnaires were administrated to the populations of Niamey and Maradi. The results show that 99% of respondents are aware of the importance of biodiversity in urban areas. They assign multiple roles to it; however, climatic and managerial reasons explain why plants are most preferred to animals in these cities. Furthermore, shade and fruits are the criteria for plant species selection, and that explains the abundance of Azadirachta indica A. Juss. and Mangifera indica L. Even though plants are preferred to animals in houses, 47% of the respondents practice animal husbandry. Most of the animals are left wandering with risks of destruction of green areas, road unsafety, and zoonotic contamination. The results of this study also showed the ignorance of 55% of the respondents about the presence of wildlife in urban areas. The proliferation of cockroaches and rats could be an indication of insanitary conditions that are faced in some areas of the cities as mentioned by 81% of the respondents. This study shows the importance of local knowledge in the identification process of urban problems.

Description: The lower-class segment of the population of the developing nations often fails to form meaningful social relations and remain disengaged from essential social institutions. The research examines those people who live in refugee-camp and sullied slum of Dhaka city and inspect how much they are socially isolated. Certain characteristics, taken as indicators to test the level of social isolation, indicate that a large segment of camp and slum dwellers are feeling isolated. However, the evidence shows no differences in the predicted direction with respect to the objective demographic variables; nonetheless, a pattern of perceived social isolation was found from the survey data.

Description: Violence by young people is one of the most visible forms of social disorder in urban settlements. This study assesses the causes and consequences of youth violence in the Kumasi metropolis. The study design was a nonexperimental cross-sectional survey. A mixed method approach facilitated the random sampling of 71 young people in the Kumasi metropolis through a stratified procedure between December 2014 and November 2015. Ten (10) participants were purposively selected and enrolled in a focus group discussion. Descriptive statistics formed the basis for the analysis. This was supported with a matched discourse analysis of the emerging themes. More than half of the youth (39, 54.9%) demonstrated history of ever engaging in violence in the past one year of whom 24 (61.5%) were without formal education. The frequency of the violence perpetuation ranged from daily engagement (3, 4%) to weekly engagement in violence (12, 17%). Principally, the categories of youth violence were manifested in noise making, rape, murder, stealing, drug addiction, obscene gestures, robbery, sexual abuse, and embarrassment. Peer pressure and street survival coping approaches emerged as the pivotal factors that induced youth violence. Addressing youth violence requires an integrative framework that incorporates youth perspectives, government, chiefs, and nongovernmental organizations in Ghana, and religious bodies.

Description: This paper seeks to examine the ethnoreligious urban violence and residential mobility in the city of Kaduna with a view to make recommendations towards ameliorating its effects by evaluating the causal factors fueling the crisis and examining the pattern and direction of the residential mobility in the city. The sources of data were both primary and secondary. The sampling technique used was purposive and random sampling from two residential districts from both the northern and southern parts of the city. A total of 1,000 questionnaires were administered within the study areas and 900 questionnaires were collected. Face-to-face interviews were conducted with major stakeholders from the two parts. The data obtained were analysed using thematic and content analysis for the qualitative data whilst the quantitative data were analysed using simple percentages. The results revealed that the factors causing the ethnoreligious urban violence and residential mobility are unemployment, social institutional breakdown, politics, and colonial impact and the pattern/direction of the residential mobility in the city of Kaduna show a clear polarization along religious lines based reactive residential mobility between the two parts of the city. Based on these results recommendations were made to assist the academia, practitioners, and policy makers.

Description: This study was conducted with the objective of finding the perceivable effect of figures and backgrounds on residential streetscapes and their connections in visual complexity. The visual complexity depends on the extent of information a viewer can observe from a visible area. The information includes a number of visual elements along the streetscapes and their diversity and interconnections. The aim of this research was to analyze the structural hierarchical visual complexity of the streetscapes, caused by varied spatial arrangement and numerous spatial connections of the perceivable visual elements. The visual elements of 60 residential streetscapes were classified into figures and backgrounds using human perception of 20 subjects. The identified figures and backgrounds were arranged in a taxonomic diagram representing their connections. These taxonomic diagrams reflect the structural hierarchical visual complexity. Finally, taxonomic entropy was applied to statistically analyze the structural hierarchical visual complexity. When the taxonomic diagram is vertically and horizontally lengthy and the arrangement of the elements of taxonomic diagram is irregular, the complexity increases depicting a large number of figures whose spatial connections impart a high visual complexity to the streetscapes.

Description: We test whether ethnic diversity in Dutch neighbourhoods and municipalities drives down associational involvement and build on earlier research in two important ways. First, we explicitly take into account the ethnic composition of local voluntary associations, distinguishing involvement in bonding (only in-group members) and bridging (with out-group members) associations. Second, we aim to explain relationships between ethnic diversity and associational involvement, testing two competing sets of predictions derived from conflict and contact theories. Using data from the Netherlands Longitudinal Lifecourse Study (2013), ethnic diversity turns out to hardly affect associational involvement negatively. Only for leisure associations, living in ethnically more diverse municipalities substantially decreases the likelihood to be involved in bonding associations, whereas higher levels of neighbourhood ethnic diversity increase the likelihood to be involved in bridging associations. Moreover, ethnic diversity indirectly affects associational involvement via interethnic contact. Higher levels of ethnic diversity increase interethnic contact which, in turn, is negatively related to involvement in bonding associations. Whereas higher levels of ethnic diversity in neighbourhoods increase perceptions of ethnic threat, these perceptions decrease with higher levels of ethnic diversity in the municipality. Perceptions of ethnic threat do not, however, affect associational involvement. Our results shed more light on the direct and indirect relationships between ethnic diversity and bonding and bridging associational involvement.

Description: To study the durability of concrete with fly ash as fine aggregate subjected to alternative attacks of freeze-thaw and carbonation, the appearance, mass loss, relative dynamic modulus of elasticity, relative compressive strength, and carbonation depth of the concrete are investigated using cyclic tests under single carbonation, single freeze-thaw, and alternation of freeze-thaw and carbonation. In addition, microstructural analysis techniques including scanning electron microscope and X-ray diffraction are adopted to reveal the deterioration mechanism of alternating freeze-thaw and carbonation. Results show that carbonation is beneficial for refining the pore structure and increasing concrete strength in the initial alternative cycle, which delays the damage from freeze-thaw cycles. Damage from freeze-thaw causes crack propagation in concrete, which leads to carbonation intensification. Compared with other test modes, concrete under alternative freeze-thaw and carbonation causes the greatest degree of deterioration during the initial freeze-thaw cycles. The carbonation depth under alternative freeze-thaw and carbonation is positively correlated with the carbonation time and the water-to-cement ratio. However, as the reactant is continuously consumed due to the expansion of crystalline ice and CaCO3, alternative cycles result in the appearance of many more new cracks in the concrete.

Description: Landslide susceptibility map aids decision makers and planners for the prevention and mitigation of landslide hazard. This study presents a methodology for the generation of landslide susceptibility mapping using remote sensing data and Geographic Information System technique for the part of the Darjeeling district, Eastern Himalaya, in India. Topographic, earthquake, and remote sensing data and published geology, soil, and rainfall maps were collected and processed using Geographic Information System. Landslide influencing factors in the study area are drainage, lineament, slope, rainfall, earthquake, lithology, land use/land cover, fault, valley, soil, relief, and aspect. These factors were evaluated for the generation of thematic data layers. Numerical weight and rating for each factor was assigned using the overlay analysis method for the generation of landslide susceptibility map in the Geographic Information System environment. The resulting landslide susceptibility zonation map demarcated the study area into four different susceptibility classes: very high, high, moderate, and low. Particle Swarm Optimization-Support Vector Machine technique was used for the prediction and classification of landslide susceptibility classes, and Genetic Programming method was used to generate models and to predict landslide susceptibility classes in conjunction with Geographic Information System output, respectively. Genetic Programming and Particle Swarm Optimization-Support Vector Machine have performed well with respect to overall prediction accuracy and validated the landslide susceptibility model generated in the Geographic Information System environment. The efficiency of the landslide susceptibility zonation map was also confirmed by correlating the landslide frequency between different susceptible classes.

Description: To study the correlation among advancing direction, strata behaviors, and rock burst induction, two physical models utilizing similar materials are established. Subsequently, the influence of advancing direction on the mining effect, caused by a fault, is studied. Moreover, the rock bursts affected by faults with different mining directions are compared and analyzed. The results show that the overlying structure varies notably, affected by fault cutting and fault dip, and the fault-affected zone and the cause of induced rock burst differ with different mining directions. However, regardless of mining directions, the overlying structure of the hanging wall is stable and fault activation is not obvious, while that of the footwall is relatively active and fault activation is violent; the risk of rock burst on the footwall is larger than that of mining on the hanging wall. Finally, an engineering case regarding two rock bursts in panel 6303 is used to verify some physical simulation results to a certain extent. Study results can serve as a reference for face layout and prevention of rock bursts under similar conditions.

Description: Infrastructure vulnerability has drawn significant attention in recent years, partly because of the occurrence of low-probability and high-consequence disruptive events such as 2017 hurricanes Harvey, Irma, and Maria, 2011 Tuscaloosa and Joplin tornadoes, and 2015 Gorkha, Nepal, and 2017 Central Mexico earthquakes. Civil infrastructure systems support social welfare, thus viability and sustained operation is critical. A variety of frameworks, models, and tools exist for advancing infrastructure vulnerability research. Nevertheless, providing accurate vulnerability measurement remains challenging. This paper presents a state-of-the-art data collection and information extraction methodology to document infrastructure at high granularity to assess preevent vulnerability and postevent damage in the face of disasters. The methods establish a baseline of preevent infrastructure functionality that can be used to measure impacts and temporal recovery following a disaster. The Extreme Events Web Viewer (EEWV) presented as part of the methodology is a GIS-based web repository storing spatial and temporal data describing communities before and after disasters and facilitating data analysis techniques. This web platform can store multiple geolocated data formats including photographs and 360° videos. A tool for automated extraction of photography from 360° video data at locations of interest specified in the EEWV was created to streamline data utility. The extracted imagery provides a manageable data set to efficiently document characteristics of the built and natural environment. The methodology was tested to locate buildings vulnerable to flood and storm surge on Dauphin Island, Alabama. Approximately 1,950 buildings were passively documented with vehicle-mounted 360° video. Extracted building images were used to train a deep learning neural network to predict whether a building was elevated or nonelevated. The model was validated, and methods for iterative neural network training are described. The methodology, from rapidly collecting large passive datasets, storing the data in an open repository, extracting manageable datasets, and obtaining information from data through deep learning, will facilitate vulnerability and postdisaster analyses as well as longitudinal recovery measurement.

Description: Fatigue life of tubular joints in offshore structures is significantly influenced by the degree of bending (DoB). The DoB exhibits considerable scatter calling for greater emphasis in accurate determination of its governing probability distribution which is a key input for the fatigue reliability analysis of a tubular joint. Although the tubular X-joints are commonly found in offshore jacket structures, as far as the authors are aware, no comprehensive research has been carried out on the probability distribution of the DoB in tubular X-joints. In the present paper, results of parametric equations available for the calculation of the DoB have been used to develop probability distribution models for the DoB in the chord member of tubular X-joints subjected to four types of bending loads. Based on a parametric study, a set of samples was prepared and density histograms were generated for these samples using Freedman-Diaconis method. Twelve different probability density functions (PDFs) were fitted to these histograms. In each case, Kolmogorov-Smirnov test was used to evaluate the goodness of fit. Finally, after substituting the values of estimated parameters for each distribution, a set of fully defined PDFs have been proposed for the DoB in tubular X-joints subjected to bending loads.

Description: Based on theories of explosive mechanics and rock fracture mechanics, the influence mechanism of rock strength on the propagation length of the primary crack in the directional fracture blasting with slotted cartridge has been investigated deeply to propose the relation equation between the rock strength and the propagation length of the primary crack. Theoretically, the maximum length am of the primary crack increases with the enhancing rock strength parameters. The explicit dynamic analysis software LS-DYNA has been used to simulate the slotted cartridge blasting in the mudstone, sandstone, and granite with different strengths in order to reveal the effect of rock strength on the propagation length and velocity of the primary crack and the stress distribution characteristics in rock. The numerical results show the primary crack easily bifurcates and attain a much shorter propagation length in the mudstone with the minimum strength, and there are radial cracks appearing in the nonslotted direction. When rock strength rises, the propagation length, velocity, and duration of the primary crack and the concentration degree of effective stress in the slotted direction will all increase in the sandstone and granite, but there is an opposite influence trend of rock strength in the stage of the initial guide crack’s formation. The cracking velocity has an overall oscillation downtrend whose swing amplitude enhances clearly with the increasing rock strength, signifying the more unsteady propagation of the primary crack in the higher strength rock.