Assessment of various parameters on 3D semantic object-based point cloud labelling on urban LiDAR dataset

Semantic labelling of LiDAR point cloud is critical for effective utilization of 3D points in numerous applications. 3D segmentation, incorporation of ancillary data, feature extraction and classification are the key stages in object-based point cloud labelling. The choice of algorithms and tuning parameters adopted in these stages has substantial impact on the quality of results from object-based point cloud labelling. This paper critically evaluates the performance of object-based point cloud labelling as a function of different 3D segmentation approaches, incorporation of spectral data and computational complexity of the point cloud. The designed experiments are implemented on the datasets provided by the ISPRS and the results are independently validated by the ISPRS. Results indicate that aggregation of dense point cloud into higher-level object analogue (e.g. supervoxels) before 3D segmentation stage offers superior labelling results and best computational performance compared to the popular surface growing-based approaches.     

Field Treatment of MTBE‐Contaminated Groundwater Using Ozone/UV Oxidation

Methyl‐tertiary butyl ether (MTBE) is often found in groundwater as a result of gasoline spills and leaking underground storage tanks. An extrapolation of occurrence data in 2008 estimated at least one detection of MTBE in approximately 165 small and large public water systems serving 896,000 people nationally (United States Environmental Protection Agency [U.S. EPA] 2008). The objective of this collaborative field study was to evaluate a small groundwater treatment system to determine the effectiveness of ultraviolet (UV)/ozone treatment in removing MTBE from contaminated drinking water wells. A pilot‐scale advanced oxidation process (AOP) system was tested to evaluate the oxidation efficiency of MTBE and intermediates under field conditions. This system used ozone as an oxidizer in the presence of UV light at hydraulic retention times varying from 1 to 3 min. MTBE removal efficiencies approaching 97% were possible with this system, even with low retention times. The intermediate t‐butyl alcohol (TBA) was removed to a lesser extent (71%) under the same test conditions. The main intermediate formed in the oxidation process of the contaminated groundwater in these studies was acetone. The concentrations of the other anticipated intermediates t‐butyl formate (TBF), isopropyl alcohol (IPA), methyl acetate (MAc), and possible co‐occurring aromatics (BTEX) in the effluent were negligible.     

River and basin morphometric indexes to detect tectonic activity: a case study of selected river basins in the South Indian Granulite Terrain (SIGT)

Abstract

The effects and influence of tectonic processes on the Anjarakandy, Thalassery, Mahe, and Kuttiyadi watersheds and rivers of the South Indian Granulite Terrain in Kerala were examined to determine their spatial heterogeneity. Drainage basin asymmetry (Af), transverse topographic symmetry factor (T), hypsometric integral and curve (HI), longitudinal profile, stream length gradient index (SL), and stream concavity index (SCI) suggest heterogeneity in tectonic influence. Clusters of geomorphic anomalies in similar lithology rule out lithologic control on drainage development. However, the orientations of the drainage networks and predominant fractures/lineaments compare closely and reveal strong tectonic influence. Though the watersheds are considered to be in an advanced stage of erosion by the low HI (<30) and high values of SCI, variations in the shape of the hypsometric curves and differences in the SCI values indicate the different influence of tectonic process from watersheds in the north to the south. Among the watersheds, the Mahe and Kuttiyadi are more sensitive to tectonic processes than the Anjarakandy and Thalassery and indicate spatial heterogeneity in the influence of tectonic activity, confirming the grouping of watersheds based on structural and drainage patterns.     

Climate change adaptation cost in the US: what do we know?

Researchers and policy makers increasingly recognize the need to adapt to future changes in climate, given that past emissions of greenhouse gases have already committed the world to some level of climate change. However, the current understanding of the costs and benefits of adaptation measures is still fairly rudimentary, and far from comprehensive. An assessment is presented of the current state of knowledge on the magnitude of adaptation costs in the United States. While incomplete, the studies suggest that adaptation cost could be as high as tens or hundreds of billions of dollars per year by the middle of this century. Key studies are identified in each sector, and the cost estimates and approaches to cost estimation are surveyed. Methodological issues are highlighted in interpreting, comparing, and aggregating adaptation cost estimates. Policy recommendations are made along with appropriate steps to make future adaptation cost studies more comparable within and across sectors and more accessible and relevant to policy and decision makers.

Policy relevance

Designing and implementing climate change adaptation policy requires good information about the effectiveness and cost of available adaptive options. The current state of knowledge on adaptation costs in the United States is assessed and significant gaps in the literature are highlighted – particularly in terms of sectoral and geographic coverage – as well as inconsistencies in methodologies and assumptions that hamper comparison across studies. Critical steps are identified that can be taken to make adaptation cost studies more accessible and useful to decision makers. The findings and recommendations are relevant to adaptation cost studies globally, not just in the United States.     

Skill assessment of global climate model wind speed from CMIP5 and CMIP6 and evaluation of projections for the Bay of Bengal

Climate Dynamics - Atmospheric and oceanic parameters derived from global climate model (GCM) simulations have received wide global attention and importance in representing the future world under...     

Implications of seismic pounding on the longitudinal response of multi-span bridges-an analytical perspective

Seismic pounding between adjacent frames in multiple-frame bridges and girder ends in multi-span simply supported bridges has been commonly observed in several recent earthquakes. The consequences of pounding include damage to piers, abutments, shear keys, bearings and restrainers, and possible collapse of deck spans. This paper investigates pounding in bridges from an analytical perspective. A simplified nonlinear model of a multiple-frame bridge is developed including the effects of inelastic frame action and nonlinear hinge behavior, to study the seismic response to longitudinal ground motion. Pounding is implemented using the contact force-based Kelvin model, as well as the momentum-based stereomechanical approach, Parameter studies are conducted to determine the effects of frame period ratio, column hysteretic behavior, energy dissipation during impact and near source ground motions on the pounding response of the bridge. The results indicate that pounding is most critical for highly out-of-phase frames and is not significant for frame period ratios greater than 0.7. Impact models without energy dissipation overestimate the displacement and acceleration amplifications due to impact, especially for elastic behavior of the frames. Representation of stiffness degradation in bridge columns is essential in capturing the accurate response of pounding frames subjected to far field ground motion. Finally, it is shown that strength degradation and pounding can result in significant damage to the stiffer frames of the bridge when subjected to large acceleration pulses from near field ground motion records.     

Microbiologically influenced corrosion in dairy effluent

In the dairy industry mild steel is used as the construction material for the effluent treatment plants, pipelines, reinforcement in concrete structures etc. The steel exposed to the dairy effluent faces corrosion due to the microbes. In the present study the role of microbes in dairy effluent on the corrosion of mild steel has been investigated. Pseudomonas sp., Streptococcus sp., Micrococcus sp., Bacillus sp., Neisseria sp. and Lactobacillus sp. were identified in dairy effluent. Corrosion rate has been estimated by weight loss measurements and polarization technique. The Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometer (XRD) studies were found helpful in investigating the chemical pathway leading to the formation of corrosion products on the mild steel during fermentation. Initiation of pitting corrosion was noticed on steel specimens by scanning electron microscope (SEM). A mechanism has been proposed for microbiologically influenced corrosion in dairy effluent.     

Case studies of damage to 19‐storey irregular steel moment‐frame buildings under near‐source ground motion

This paper describes the three‐dimensional nonlinear analysis of six 19‐storey steel moment‐frame buildings, designed per the 1997 Uniform Building Code, under strong ground motion records from near‐source earthquakes with magnitudes in the range of 6.7–7.3. Three of these buildings possess a reentrant corner irregularity, while the remaining three possess a torsional plan irregularity. The records create drift demands of the order of 0.05 and plastic rotation demands of the order of 4–5% of a radian in the buildings with reentrant corners. These values point to performance at or near ‘Collapse Prevention’. Twisting in the torsionally sensitive buildings causes the plastic rotations on the moment frame on one face of the building (4–5% of a radian) to be as high as twice of that on the opposite face (2–3% of a radian). The asymmetric yield pattern implies a lower redundancy in the lateral force‐resisting system as the failure of the heavily loaded frame could result in a total loss of resistance to torsion. Copyright © 2006 John Wiley & Sons, Ltd.     

Observations of the atmospheric surface layer parameters over a semi arid region during the solar eclipse of August 11th, 1999

This paper discusses the observations of the Atmospheric Surface Layer (ASL) parameters during the solar eclipse of August 11th, 1999. Intensive surface layer experiments were conducted at Ahmedabad (23‡21′N, 72‡36′E), the western part of India, which was close to the totality path. This rare event provided by nature is utilised to document the surface layer effects during the eclipse period using measurements of high frequency fluctuations of temperature, tri-axial wind components as well as mean parameters such as temperature, humidity, wind speed and subsoil temperature. Analysis showed that during the eclipse period, the turbulence parameters were affected leading to the suppression of the turbulence process, the main dynamic process in the atmospheric boundary layer, while the mean parameters showed variations within the natural variability of the observational period. The spectra of the wind components and temperature indicated decrease in spectral power by one order in magnitude during the eclipse period. The rate of dissipation of turbulent kinetic energy is found to decrease by more than one order during the eclipse period. The stability parameter showed a change from unstable to stable condition during the period of eclipse and back to unstable condition by the end of eclipse