Complex Urban Conditions Research Articles

Observations of airflow around a supertall curved building and its impact on temperature and humidity in Houston's urban center

Characterization of realistically shaped skyscrapers embedded in non-uniform neighbourhoods experiencing intricate weather patterns remains inadequately investigated. Aiming to close this gap, the Center for Multiscale Applied Sensing team deployed its mobile observatory in the street canyons around the curved Wells Fargo Plaza skyscraper in downtown Houston, TX. Three deployments allowed airflow observations under different inflow wind and thermodynamic stability conditions. Doppler lidar measurements reveal that when inflow hits the curved wall of the skyscraper, perpendicular canyons experience similar vortex configurations creating two windward and two leeward circulations. Windsond measurements support that buoyancy within the deep street canyons can generate thermal updrafts as strong as 2 m s−1 which is sufficient to overturn the mechanical downwash under gentle wind conditions. Canyons experiencing venting during the daytime were observed to be more thermodynamically stable at night while thermodynamically stable canyons during the day were observed to be more thermodynamically unstable at night owing to the accumulation of heat near street-level. Fourier decomposition of the vertical velocity measurements shows that in all cases flow exhibited high Reynolds numbers and was composed of turbulent eddies of predominantly 6 and 15 min periods. This observational dataset provides insights to assess wind load, pedestrian comfort, urban air mobility, and natural ventilation and may be used as a benchmark for numerical model and wind tunnel studies attempting to represent realistically complex urban conditions.

Urban geophysical exploration: case study in Chengdu International Bio-City

Abstract Understanding the shallow geological structure of urban areas is crucial for effective planning and development of underground spaces. Geophysical methods that are well-suited for site-specific investigation and have robustly anti-interference capabilities can provide important geological information for urban areas. In support of investigating the 3D geological structure of the shallow subsurface in Chengdu International Bio-City, a geophysical exploration study was conducted using three methods: the electrical resistivity tomography (ERT), micro-seismic exploration and opposing-coil transient electromagnetic method (OCTEM). Results from the study showed that the ERT method was greatly affected by local high-resistance bodies, construction sites and industrial currents, therefore leading to poor detection results that did not match well with the area’s layered structure characteristics. The micro-seismic exploration method showed good layering effects and correlation with the drilling data in the elevation range of ∼350 to 436 m, but poor layering effects and low correlation with drilling data in the elevation range of ∼235 to 350 m, with relatively slow construction efficiency. The OCTEM showed good correlation with the drilling data for shallow depths up to 200 m and good identification capabilities for gypsum and mudstone in the area. Additionally, the instrument’s anti-interference ability was suitable for complex urban conditions. Thus, OCTEM was selected for the area-based exploration with a 100 × 10 m grid, rapidly obtaining 3D resistivity information for depths up to 200 m in the study area. By integrating the 3D resistivity information with known engineering geological information, a comprehensive 3D geological model of the study area was created.

AMM: An Adaptive Online Map Matching Algorithm

Online map matching is essential for some location-based services, such as car navigation. However, due to GPS measurement errors and/or the lack of sufficient information, the performance of most existing online algorithms will degrade in the increasingly complex traffic environment. In this paper, we propose an adaptive online map matching algorithm called AMM. The basic idea is that AMM should be able to calibrate GPS observation data for various measurement errors and under complex urban conditions. First, we establish a collaborative evaluation model between GPS points and candidate points to effectively filter low-quality GPS measurement points, dynamically set the weights of different features and comprehensively select the best candidate points. Second, we propose a retrospective correction mechanism to correct the previous matching results when more information is available, which will help improve the accuracy of future GPS points. Furthermore, we define parameter self-tuning rules for AMM to enhance its portability by avoiding time-consuming parameter tuning steps. We conduct extensive experiments to evaluate the performance of AMM on real vehicle trajectory datasets. The experiment results show that AMM outperforms its counterparts by up to 32% in terms of accuracy and its performance in different traffic conditions is more stable.

Addis Ababa’s sefer, iddir, and gebbi

This research is motivated by the scholarly calls for new concepts and analytic tools for documenting, analysing, and theorizing complex urban territories such as those of cities in Africa. With implicit comparative intent, it takes the case of Addis Ababa city and its old and typifying places—the sefer, to develop and test a new architectural transdisciplinary research methodology referred to as the trinocular. By way of this methodology, it unearths and introduces sefer, iddir, and gebbi of Addis Ababa as not only socio-spatial phenomena but concepts and vocabulary for a located and nuanced reading of the city itself. Sefer are introduced as flexible boundary conditions that are primarily cognized by their dwellers—results of indigenous and autochthonous foundation and continued processes of self-actualization by communities that construct them. Iddir is unearthed as a form of social capital embedded in sefer that appears in the structures of relations among residents. And the gebbi as an urban spatial typology that constitutes the sefer’s morphology—the last frontier of communality just prior domestic spaces which, in many cases, can be a single multi-functional room. These concepts and vocabulary, it is argued, in both practical and metaphoric sense, should be the starting point of new urban imaginaries for Addis Ababa. Urban planning and housing projections thus, should draw inspiration from these notions, elements, and phenomena. Furthermore, lessons learnt from the trinocular and the findings are presented as new avenues for architectural research in similar, less-known, and complex urban conditions as the sefer of Addis Ababa.

A Mapping Experiment of Belfast Films: The Mighty Celt and Belfast Girls

This study aims to show how the act of mapping could contribute to our existing knowledge about cities. Mapping has long been used as a tool for understanding physical space. Lately, scholars also used it as a method of examining the places on the screen. Belfast, a city in which a profound sectarian dispute exists, has become the setting of many conflict-themed films. This research claims that mapping film locations in Belfast could provide an archive to examine the transformation of urban texture and architecture. Analysis of the city image in two films, The Mighty Celt (2005) and Belfast Girls (2006), could help to reveal the physical change of the city from different perspectives. In the first one, Belfast is a hostile background experienced from the eyes of a young boy, while the second one documents the life of two girls from diverse backgrounds, a Protestant and a Catholic. Both films are set in Northern Ireland during the post-Trouble period, during which the division between the two groups persisted. These films make a contemporary portrait of Belfast as a divided city where armed conflicts have ended, but physical segregation remains. By analysing these two narratives, the study will try to interpret the complex urban conditions in Belfast at the beginning of the century.

The TEA Evaluation Toolkit: Assessing Transdisciplinary, Experiential, and Adaptive Learning and Teaching in Urban Design Studios

New pedagogic approaches combining Transdisciplinary, Experiential, and Adaptive perspectives are emerging to respond to increasingly complex urban conditions. By addressing the gap in current urban design studio education, the study defined a framework to assist teachers in designing novel teaching formats based on TEA learning approaches. The framework proposed provides a reference to set up TEA urban design studios and an assessment toolkit to assess their effectiveness in learning and teaching. The comparative analysis of two studio applications shows interdependence of TEA learning and teaching dimensions and generates transferrable recommendations to support a new urban design studio pedagogy that effectively responds to contemporary societal and environmental challenges.

Enhanced GNSS Spoofing Detector via Multiple-Epoch Inertial Navigation Sensor Prediction in a Tightly-Coupled System

Global navigation satellite system (GNSS) signals have open structure and weak power, which is vulnerable to spoofing attacks. The Innovation-based detection technique has been proved effective for spoofing detection in an integrated navigation system. However, it employs spoofed priori estimate of pseudorange to construct innovation, showing shortcomings like limited detection probability for slowly-varying spoofing attacks, long time to alarm (TTA), and high false alarm probability. This work proposes an enhanced innovation-based spoofing detector via multiple-epoch inertial navigation sensor (INS) prediction. An additional INS unit is added, which is corrected by extended Kalman Filter (EKF) every <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${N}$ </tex-math></inline-formula> epoch. Its output is used to replace the spoofed priori estimate in the EKF and then construct an improved innovation. Compared with the conventional innovation, the improved one can be immune to spoofing during multiple epochs and accumulate more abnormal energy due to spoofing attacks. In addition, an innovation bias mitigation method is presented, which exploits the mean of innovation of previous epochs to predict the immediate innovation bias and thus reduces the probability of false alarm. The overall spoofing detection performance is evaluated using both simulation data and hardware-based experiment data collected in Beihang university. A driving test was also carried out to verify its performance in complex urban conditions. Results show that the proposed detector significantly improves the detection performance under slowly-varying spoofing attacks and reduces the probability of false alarm compared with the conventional detector.

Applied research by design: an experimental collaborative and interdisciplinary design charrette

ABSTRACT This article reports on one experimental case of interdisciplinary collaboration on a design and planning exercise across several scales – local through urban to regional – and sectors – private, public, scholarly, and interest groups. The case is a collaborative and interdisciplinary design charrette on sustainable urbanism for envisioning the future of the Greater Metropolitan Area of Florence in Italy. The experiment entailed the attempt to integrate complex urban conditions via the design charrette in order to create more healthy and sustainable cities. This collaborative work shows how conditions that are at times not addressed comprehensively nor holistically can be combined through doing applied research by design; where design is understood as a process of discovery and creation that results in synthesis. The article details the methodology applied, and provides an initial assessment on the process that the charrette employed. Moreover, it highlights some professional and policy implications of the effort. Finally, it provides a provisional assessment on learning outcomes and addresses opportunities to improve future exercises of this nature.

Shadow Detection and Compensation from Remote Sensing Images under Complex Urban Conditions

Due to the block of high-rise objects and the influence of the sun’s altitude and azimuth, shadows are inevitably formed in remote sensing images particularly in urban areas, which causes missing information in the shadow region. In this paper, we propose a new method for shadow detection and compensation through objected-based strategy. For shadow detection, the shadow was highlighted by an improved shadow index (ISI) combined color space with an NIR band, then ISI was reconstructed by the objects acquired from the mean-shift algorithm to weaken noise interference and improve integrity. Finally, threshold segmentation was applied to obtain the shadow mask. For shadow compensation, the objects from segmentation were treated as a minimum processing unit. The adjacent objects are likely to have the same ambient light intensity, based on which we put forward a shadow compensation method which always compensates shadow objects with their adjacent non-shadow objects. Furthermore, we presented a dynamic penumbra compensation method (DPCM) to define the penumbra scope and accurately remove the penumbra. Finally, the proposed methods were compared with the stated-of-art shadow indexes, shadow compensation method and penumbra compensation methods. The experiments show that the proposed method can accurately detect shadow from urban high-resolution remote sensing images with a complex background and can effectively compensate the information in the shadow region.

Urban Black-Odor Water Remote Sensing Mapping Based on Shadow Removal: A Case Study in Nanjing

Urban black-odor water is a serious water environmental problem worldwide that seriously affects the living environment and the health of residents. The detection of black-odor water is a primary problem of centralized governance. Remote sensing is an effective means for water-quality monitoring. However, in most urban areas, with their complex underlying conditions, black-odor water always shows an uncertain distribution and small area. Furthermore, because of similar spectral characteristics, it is easily confused with dark objects such as asphalt roads, dark roofs, bridges, river levees, and building shadows. In this article, we propose a new black-odor water detection method, without shadow misjudgment, for complex urban conditions. A remote sensing image from the Chinese high-resolution satellite Gaofen-2 (GF-2) was used for detection. Using in situ water-quality measurement data for verification, the results showed that the proposed method achieved an accuracy of 85.7% while reducing the false alarm rate to 3.5%. Compared to four other existing methods, the proposed method proved to be more practical because it can reduce the false extraction of nonblack-odor water to the greatest extent possible while ensuring accuracy The method proposed in this article has a good effect on the extraction of black-odor water in Nanjing City. Therefore, our method can be applied widely to screening and management of large-scale urban black-odor water and can provide reliable data for centralized treatment.

Multimodal mapping — a methodological framework

Framed within a broader discussion of demographic marginalisation in urban regeneration projects, this paper considers how the non-visual might be understood, valued and represented through an expanded mode of site analysis that allows for a nuanced reading of demographically complex urban conditions. Drawing on detailed fieldwork in the Melbourne suburb of Footscray, this paper outlines a multimodal mapping technique that spatialises and materialises emplaced and embodied knowledge. Sensory rhythms associated with occupation of space are recorded, and immersive ethnographic techniques are used to supplement the identified rhythms. The sensory data is then translated into multimodal mapping diagrams based on the concept of vertical montage where different spheres such as sound and image could be linked to be perceived together. It is a method that attempts to highlight the sociality of the senses, while looking specifically at the interplay between space, time and the social body in everyday interactions, enabling designers to grasp the existing sensorial realm, to represent it in a way that retains its complexity and to make use of this knowledge within the parameters of architectural design.

Design and intelligent control of building integrated photovoltaic system

The concept of building an integrated photovoltaic (BIPV) system attracts increasing attention due to its promising performance in energy-saving. However, the efficiency of the BIPV system may rapidly deteriorate when the photovoltaic (PV) array is partially shaded by clouds and shadows of the surrounding buildings. This paper presents a novel configuration of a large-scale BIPV system, and the intelligent maximum power point tracking approach is also studied. First, the PV panels installed on each side of the building are designed as the BIPV units (BIPV-Us) with different sizes, and the size of each BIPV-U is determined by the location and surroundings of the target building. Second, the numerical model of the BIPV system is established as an optimization problem, and an intelligent algorithm in our previous work, namely, decentralizing and coevolving differential evolution, is employed to solve this problem. Finally, the proposed BIPV system is tested by simulation experiments. According to the experimental results, the proposed BIPV system and its intelligent control approach can achieve promising performance under complex urban conditions.

Should big cities grow? Scenario-based cellular automata urban growth modeling and policy applications

The formation of ‘Urban Networks’ has become a wide-spread phenomenon around the world. In the study of metropolitan regions, there are competing or diverging views about management and control of environmental and land-use factors as well as about scales and arrangements of settlements. Especially in China, these matters alongside of regulatory aspects, infrastructure applications, and resource allocations, are important because of population concentrations and the overlapping of urban areas with other land resources. On the other hand, the increasing sophistication of models operating on iterative computational power and widely-available spatial information and analytical techniques make it possible to simulate and investigate the spatial distribution of urban territories at a regional scale. This research applies a scenario-based Cellular Automata model to a case study of the Changjiang Delta Region, which produces useful and predictive scenario-based projections within the region, using quantitative methods and baseline conditions that address issues of regional urban development. The contribution of the research includes the improvement of computer simulation of urban growth, the application of urban form and other indices to evaluate complex urban conditions, and a heightened understanding of the performance of an urban network in the Changjiang Delta Region composed of big, medium, and small-sized cities and towns.

Impacts of combined sewer overflows on a large urban river – Understanding the effect of different management strategies

To support decision makers in planning effective combined sewer overflow (CSO) management strategies an integrated modelling and impact assessment approach has been developed and applied for a large urban area in Berlin, Germany. It consists of an urban drainage model, a river water quality model and a tool for the quantification of adverse dissolved oxygen (DO) conditions in the river, one of the main stressors for urban lowland rivers. The coupled model was calibrated successfully with average Nash-Sutcliffe-efficiencies for DO in the river of 0.61 and 0.70 for two validation years. Moreover, the whole range of observed DO concentrations after CSO down to 0 mg L−1 is simulated by the model. A local sensitivity analysis revealed that in the absence of CSO dissolved oxygen principally depends on phytoplankton dynamics. Regarding CSO impacts, it was shown that 97% of the observed DO deficit can be explained by the three processes (i) mixing of river water with CSO spill water poor in DO, (ii) reduced phytoplankton activity due to CSO-induced turbidity and (iii) degradation of organic matter by heterotrophic bacteria. As expected, process (iii) turned out to be the most important one. However depending on the time lag after CSO the other processes can become dominant. Given the different involved processes, we found that different mitigation schemes tested in a scenario analysis can reduce the occurrence of critical DO deficits in the river by 30–70%. Overall, the study demonstrates that integrated sewer-river-models can be set up to represent CSO impacts under complex urban conditions. However, a significant effort in monitoring and modelling is a requisite for achieving reliable results.

Validation of sensitivity and reliability of GPR and microgravity detection of underground cavities in complex urban settings: Test case of a cellar

Abstract We test here the feasibility of ground-penetrating radar (GPR) and microgravity methods in identifying underground voids, such as cellars, tunnels, abandoned mine-workings, etc., in complex urban conditions. For this purpose, we selected a cellar located under a private lot in a residential quarter of the town of Senec in Western Slovakia, which was discovered by chance when a small sinkhole developed on the yard just two meters away from the house. The size of our survey area was limited 1) by the presence of a technical room built at the back of the yard with a staircase leading to the garden, and 2) by the small width of the lot. Therefore the geophysical survey was carried out only in the backyard of the lot as we were not permitted to measure on neighbouring estates. The results from the GPR measurements obtained by the GSSI SIR-3000 system with 400 MHz antenna were visualized in the form of 2D radargrams with the corresponding transformed velocity model of studied cross-sections. Only the profiles running over the pavement next to the house yielded interpretable data because the local geological situation and the regular watering of the lawn covering prevailingly the backyard caused significant attenuation of the emitted GPR signal. The Bouguer gravity map is dominated by a distinctive negative anomaly indicating the presence of a shallow underground void. The quantitative interpretation by means of Euler deconvolution was utilized to validate the depth of the center and location of the cellar. Comparison with the gravitational effect of the cellar model calculated in the in-house program Polygrav shows a quite good correlation between the modelled and observed fields. Only a part of the aerial extent of the anomaly could be traced by the used geophysical methods due to accessibility issues. Nevertheless, the test cellar was successfully detected and interpreted by both methods, thus confirming their applicability in similar environmental and geotechnical applications, even in complex urban conditions.

Extraction of the building region from airborne LiDAR point clouds under complex urban conditions

Airborne LiDAR technology provides large quantities of three-dimensional point clouds coordinates for detecting buildings.To effectively identify the building region from the vegetation,the authors adopt a progressive densification TIN method to filter no-ground points.After removing some point clouds whose height is less than 3m from ground surface and isolated point clouds,a binary grid cell is produced based on no-ground points.Next,defined segmentation operators are used to disconnect the possible link between buildings and vegetation.Two kinds of regions are clustered based on height difference criteria using the region growing method.Then building regions are extracted according to large slope density values.Finally,a morphological closing operator is applied to fill small holes and smooth edges of extracted building regions.Three typical areas with complex urban conditions were selected to test this algorithm.The results show that this algorithm gives a comparative performance with a precision of over 91 percent in quality and completeness.The results also demonstrate that this algorithm can automatically recognize buildings.

Agamben’s urbanism of exception: Jerusalem’s border mechanics and biopolitical strongholds

Grounded in Agamben’s spatial ontology, this paper analyses complex urban conditions in the West Bank, extracting phenomena of contested border zones that act as a microcosm of contemporary urban reality. Repositioning Agamben’s spatial exception at the urban scale, the argument is made for expanding from an isolated camp instrumentalism into a sustained analytical apparatus that goes, possibly, beyond the nested borders and biopolitical territorialisation of the case study. By looking at the capacity of Agamben’s discourse to enhance the study of urban phenomena, we suggest the possibility of visualising an urbanism of exception through a categorisation of fields of tension, hinting at the numerous forces acting on space beyond physical structures. This framework, far from being normative and over-comprehensive, attempts to open possible paths of interpretation about exceptionality, conceiving the city of exception as the ulterior vantage point that oversees its evolution from a sovereign mechanism to a spatial materialisation. By applying this analysis on Jerusalem it becomes clear that far from being a linear or gradual sequence, or acting just as bi-dimensional borders, spaces of exception in the city are like the city itself: multiple, parallel, crosscutting and relentless.

Neoliberalism and the Neoauthoritarian City in China—Contexts and Research Directions: Commentary in Conversation with Jennifer Robinson's Urban Geography Plenary Lecture

Emerging research on comparative neoliberalism at the urban scale seeks to trace its diffusions and document its contours and trajectories in regions beyond the trans-Atlantic corridor. Discovering geographical variation in neoliberal policy should produce more incisive understandings of neoliberalism's creative transformations, yet the emergent research on comparative urban policy may route uncomfortably close to the world of world and global cites. This brief discussion considers expanding places of inquiry to non-growth economic contexts and complex urban conditions in the world of cities. It introduces contemporary conditions of urban political economy in the People's Republic of China, where neoliberalization works in the interests of the party-state and resists critical analysis in association with debates over strains of neoconservatism (neoauthoritarism, neosocialism, and statism) in the Chinese academy and their mutual imbrication in an array of complex issues.