Geometry Data Research Articles

Measurement of gas detonation blast loads in semiconfined geometry

The ignition and explosion of combustible vapor clouds represents a significant hazard across a range of industries. In this work, a new set of gas detonations experiments were performed to provide benchmark blast loading data for non-trivial geometry and explosion cases. The experiments were designed to represent two different accident scenarios: one where ignition of the vapor cloud occurs shortly after release and another where ignition is delayed and a fuel concentration gradient is allowed to develop. The experiments focused on hydrogen-air and methane-oxygen detonations in a semiconfined enclosure with TNT equivalencies ranging from 9 g to 1.81 kg. High-rate pressure transducers were used to record the blast loads imparted on the interior walls of a 1.8 m × 1.8 m × 1.8 m test fixture. Measurements included detonation wave velocity, peak overpressure, impulse, and positive phase duration. A comparison of the pressure and impulse measurements with several VCE models is provided. Results show that even for the most simplified experimental configuration, the simplified VCE models fail to provide predictions of the blast loading on the internal walls of the test fixture. It is shown that the confinement geometry of the experiment resulted in multiple blast wave reflections during the initial positive phase duration portion of the blast loading, and thus, significantly larger blast impulse values were measured than those predicted by analytical models. For the pressure sensors that experienced normally-reflect blast waves for the initial blast impulse, the Baker-Strehlow and TNT equivalency models still struggled to accurately capture the peak overpressure and reflected impulse. The TNO multi-energy model, however, performed better for the case of simple normally-reflected blast waves. The results presented here may be used as validation data for future model or simulation development.

Information Theoretic Modeling of High Precision Disparity Data for Lossy Compression and Object Segmentation

In this paper, we study the geometry data associated with disparity map or depth map images in order to extract easy to compress polynomial surface models at different bitrates, proposing an efficient mining strategy for geometry information. The segmentation, or partition of the image pixels, is viewed as a model structure selection problem, where the decisions are based on the implementable codelength of the model, akin to minimum description length for lossy representations. The intended usage of the extracted disparity map is to provide to the decoder the geometry information at a very small fraction from what is required for a lossless compressed version, and secondly, to convey to the decoder a segmentation describing the contours of the objects from the scene. We propose first an algorithm for constructing a hierarchical segmentation based on the persistency of the contours of regions in an iterative re-estimation algorithm. Then, we propose a second algorithm for constructing a new sequence of segmentations, by selecting the order in which the persistent contours are included in the model, driven by decisions based on the descriptive codelength. We consider real disparity datasets which have the geometry information at a high precision, in floating point format, but for which encoding of the raw information, in about 32 bits per pixels, is too expensive, and we then demonstrate good approximations preserving the object structure of the scene, achieved for rates below 0.2 bits per pixels.

Assessing the Accuracy of Paleodischarge Estimates for Rivers on Mars

AbstractEstimates of river paleodischarges have been used to constrain the former climate of Mars. Paleodischarge has been calculated using mechanistic approximations of the channel bed‐shear stress at the threshold of particle motion or correlative width‐discharge relations derived from empirical terrestrial hydraulic geometry data. We apply both these methods to a study set of gaged terrestrial rivers with field‐measured bankfull properties to assess the reliability of discharge estimates given similar uncertainties as ancient martian rivers. We find that the threshold method yields conservative values, provided a reasonable grain size is used. However, we find that digital elevation models of a similar resolution to those constructed from Context Camera (CTX) data may not be of sufficient resolution to be useful for estimating paleohydrologic conditions. Results from our analysis demonstrate the inherent uncertainties when approximating paleodischarges on Mars and stress the need to consider realistic boundary conditions when determining such values.

Statistical modelling of roadside and urban background ultrafine and accumulation mode particle number concentrations using generalized additive models

Quantification of the exposure of urban residents to ultrafine particle number concentrations (UFP) is challenging due to its high spatial and temporal variability. Hence, statistical models, e.g. generalized additive models (GAM), may be used to estimate time series or spatial characteristics of UFP. The GAM approach allows the representation of non-linear relations of a response variable with explanatory variables without the need to pre-define model functions. Up to now, GAMs were usually fitted to UFP data from a single site or from mobile measurement campaigns with limited temporal coverage. In this study, GAMs were used to determine UFP, accumulation mode particle (ACC) and total number concentration (TNC) at five urban sites in the cities of Leipzig and Dresden, Germany for the period 2011–2013. As explanatory variables, reanalysis data sets of meteorological quantities, urban geometry and traffic volume data were evaluated. Variables causing concurvity, which is the equivalent to collinearity in non-linear model approaches, were neglected to guarantee the interpretability of the final models. The models were then validated in a ten-fold cross-validation approach. The final models contained smooth functions for the building surface fraction, planetary boundary layer height, traffic volume, air temperature, wind direction, atmospheric pressure, relative humidity, global radiation and precipitation. Adjusted coefficients of determination (R2adj.) for the final models were R2adj. = 0.44 for UFP, R2adj. = 0.51 for ACC and R2adj. = 0.48 for TNC. Coefficients of determination of the cross-validation were in a similar range (0.44 for UFP, 0.51 for ACC, 0.49 for TNC). Finally, our study shows that GAMs are able to represent important processes that contribute to the particle number concentration from the smooth functions, i.e. emission, dilution, nucleation, deposition and long-range transport.

Approaching BIM-GIS Integration for 3D Evacuation Planning Requirement Using Multipatch Geometry Data Format

Building Information Modelling (BIM) is known as a new technology that developed specifically to serve the architecture designing activities. It is used as a tool for researchers in Architecture, Engineering and Construction (AEC) fields to collaborate between different parties in order to manage the building information. Currently, there are plenty of researches that discussed on the concept of translating data between BIM into Geographical Information System (GIS) for various purposes. This trend leads this paper to focus on the method and findings of integrated 3D technologies between GIS and BIM. The implementation of integration between two different formats requires deep understanding about the core of both platforms such as differences and similarities between both formats. It is important to identify all related aspects of evacuation such as least risk paths, path simplicity, navigable network improvement, more detailed routes, and human behavior. To fulfil the paper research topic of Approaching BIM-GIS Integration for 3D Evacuation Planning Requirement Using Multipatch Geometry Data Format, four major concepts were the main focus namely; BIM-GIS Integration Method, Integration Data Level, Integrated Data Consideration and Requirement Analysis. Digital component involves was Revit Autodesk as BIM 3D development model software, the final integrated data format was 3D multipatch geometry and ArcGIS Pro v2.2 software used for 3D model visualization to conduct evacuation planning. The requirement for data integration and indoor evacuation planning analysis were also itemized where plenty of specific decision to be taken on based on the capabilities of current technology. Future research will focus on access-to-road strategy to test the connection of indoor spatial networks with outdoor spatial networks that based on the different data structure (BIM/vector and DEM/raster) for detailed 3D evacuation planning.

Numerical simulation of hydro-mechanical constraints on the geometry of a critically tapered accretionary wedge

A critically tapered active accretionary wedge was simulated using a numerical analysis of plastic slip-line theory to understand the mechanics of morphologic evolution. The concept of critical state soil mechanics was applied to describe the entire wedge area overlying a basal decollement fault. Presuming a condition of two-dimensional plane strain along the compressional direction, we obtained the numerical solution of conjugate plastic slip lines at a critical state of stress defined by the Coulomb yield criterion. The velocity vectors were obtained by applying the associate flow rule with the boundary conditions at the upper surface of the wedge. Finally, the detachment was determined from the effective stress condition inside the wedge and the sliding friction coefficient along the fault. Our numerical simulations demonstrate that the morphology of a critically tapered wedge is dependent on the frictional strengths of both the wedge materials and the basal fault. The critical taper angle decreases with increasing internal friction angle and decreasing basal friction coefficient. The results also revealed that the pore pressure controls the morphology of the accretionary wedge for cohesive sediments but not for non-cohesive materials. The effect of pore pressure on the morphology of a critically tapered accretionary wedge becomes more significant as the cohesion increases. Assuming that the cohesion is very low, we could infer the ranges of strengths that most observed wedge geometry data have 0.3–0.6 for the basal friction coefficient and ~35–45° for the internal friction angle of the wedge materials.

Fluid flow in a diametrally expanded CANDU fuel channel – Part 1: Experimental study

The overall aim of this study is to develop and validate experimental and computational capabilities to provide high-resolution isothermal fluid velocity data for nuclear reactor investigations. The current work presents full-field velocity data in a 1:1 replica of a 37-element CANDU nuclear fuel bundle using the Magnetic Resonance Velocimetry (MRV) measurement technique. The diameter of the pressure tube is 6% larger than at beginning-of-life to simulate the long-term aging process in an actual CANDU nuclear reactor due to diametral creep at end-of-life conditions. In Part 1, the MRV technique is presented with a focus on measurement errors and the estimation of these errors. The three-dimensional, three-component mean velocity field inside the fuel channel, including the subchannel flow between the fuel elements, is provided at a resolution of 0.78 × 0.78 × 0.78 mm3. The MRV data is validated through bulk flow rate calculations and Laser Doppler Velocimetry measurements conducted at selected locations inside the flow system. Overall, the deviations in the full-field MRV data are low except for local differences in regions with high convective acceleration and high velocity. The measurement accuracy can be improved by applying newly developed MRV sequences that are insensitive to these effects. In this specific experiment, it is found that up to 35% of the coolant bypasses the fuel bundle in a 6% diametrally expanded pressure tube containing a single bundle. The data is used as a reference for a companion paper (Part 2), which presents a computational fluid dynamics approach using an implicit large eddy simulation. In conclusion, the presented experimental methodology provides accurate full-field mean velocity data in complex channel geometries. More realistic flow experiments in replicas of entire fuel channels can be investigated in detail with relatively little effort and in a short time.

Assessing error in the 3D discontinuity-orientation distribution estimated by the Fouché method

Realistic discontinuity network modelling of rocks requires the accurate input of the three-dimensional discontinuity orientation distribution (3DDOD), but in practice, access to such three-dimensional information is limited. Fouché recently developed a method for estimating the 3DDOD from one-dimensional scanline-mapping observations. However, little is known about the error in such 3DDOD estimates. This study focuses on (1) the error and its possible contributors, (2) error prediction, and (3) error mitigation. An error investigation based on synthetic discontinuity geometry data reveals that the 3DDOD estimates are not always accurate. The error is significantly impacted by three factors: the Fisher constant (к), the angle between the major discontinuity plane and the mapping scanline (θ), and the discontinuity sample size (n), with larger к, θ, or n values contributing to lower errors. This к-, θ-, and n-dependent error appears to be inherently related to the sample density, which is defined as the pole number per unit cell (1° × 1°) in the Fouché method.Additionally, a predictor of the error based on an error-and-factors empirical relationship is developed to provide precise error prediction and optimize the scanline sampling for error mitigation. The weakness of the developed predictor is also disclosed.

An integrated methodology for the prognosis of ballast degradation in railway turnouts

This study proposes an integrated methodology for modelling and predicting ballast degradation in turnouts by exploiting loaded track geometry data. The rate of increase in track irregularities with respect to the cumulative loading of the track is the index of ballast degradation to be predicted. The methodology combines the fractal analysis method with probabilistic modeling and Bayesian inference to design a prognostic tool that forecasts the expected ballast degradation rate over a period of three months. The foundation of the proposed method is a universal degradation model for the ballast in turnouts, which fuses technological, operational, and environmental information to prognose the rate of ballast deterioration. The methodology has been verified on 15 different turnouts of the Danish railway infrastructure.

Analytical body forces in numerical actuator disc model of wind turbines

An analytical model for representing body forces in numerical actuator disc models of wind turbines is developed and validated. The model is based on the assumption that the rotor disc is subject to a constant circulation modified for tip and root effects. The model comprises expressions for both the axial and the azimuthal force distributions, and is generalized to be utilized for all kinds of inflow, including wind shear, turbulence, and shadow effects in wind farms. The advantage of the model is that it does not depend on any detailed knowledge concerning the wind turbine being analysed, but only requires knowledge regarding the rated wind speed and nameplate capacity. To validate the analytical model, results are compared to numerically generated results using detailed information regarding geometry and airfoil data for the 2 MW Tjaereborg wind turbine and the 10 MW DTU reference turbine. The comparisons show very good agreement between the loadings using the new analytical model and the airfoil data based method for the two tested wind turbines, demonstrating that the analytical model is a simple and reliable way of introducing body forces in actuator disc simulations without any prior knowledge of the wind turbine being analysed.

Detection and calibration characteristics of the visible and near-infrared imaging spectrometer in the Chang’e-4

Chang’e 4 is a robotic lunar exploration mission operated by the China National Space Administration and was to pull off the first-ever soft landing of space hardware on the mysterious lunar far side. The Visible and Near-IR Imaging Spectrometer (VNIS) is one of the main scientific instruments onboard the Chang’e 4 lunar rover. In order to analyze the lunar surface mineral composition, the VNIS was mounted on the front of the rover and detects lunar objects with a 45° visual angle to obtain spectra and geometry data to make mineralogical and compositional measurements. The VNIS is the same as the one in the Chang’e 3 Yutu rover and consists of a visible and near-infrared imaging spectrometer (0.45–0.95 µm), a shortwave IR spectrometer (0.9–2.4 µm), and a calibration unit with dust-proofing functionality. Here, we describe detection and calibration characteristics of the VNIS, which provides valuable information for scientific data processing and applications.

P2427The development of a computational fluid dynamics pipeline for the study of tetralogy of Fallot and coarctation of the aorta in a developing world context

Abstract Background Tetralogy of Fallot (ToF) and coarctation of the aorta (CoA) each constitute approximately 7% of congenital heart disease (CHD) births worldwide. Compared to developed countries, developing countries have a disparate level of access to prompt diagnosis and treatment for these diseases. Computational fluid dynamics (CFD) approaches implemented on routinely available non-invasive imaging data may yield low-cost improvements to the management of these patients. Purpose The purpose of this research is to develop a patient-specific computational pipeline that allows the modelling of blood flow in diseased arteries of patients suffering from ToF and CoA. The project aims to prove the feasible use of broadly available imaging techniques - CT angiograms (CTA) and echocardiographs (echo) - for achieving this in low-to-middle income countries. The capability of the pipeline will be demonstrated through a qualitative study of the effects of different systemic to pulmonary shunt configurations used in the palliative treatment of ToF. In addition, the effects of idealised stent configurations on the blood flow through the aorta of a patient with CoA will be studied. Methods A retrospective search through the hospital database was conducted to select suitable CTA data for a CoA and ToF case. Data for patient A, a five-month-old child with typical CoA, and patient B, a twelve-month-old child with typical ToF who had a central shunt in place, was found. Echo data was obtained for patient A through an investigation protocol which focused on CFD application whereas there was no echo data available for patient B. As a result, idealised volume flow rate data was implemented for patient B. Geometries for patient A and patient B were extracted and volume discretisation was implemented for grid independence testing. The Navier-Stokes governing equations for fluid flow were solved using the open source software, OpenFOAM, for the transient case where inlet volume flow rate was defined for four cardiac cycles. Figure 1 shows key features of the flow in the shunt and pulmonary branches (A), the aortic arch (B), the inlet at the ascending aorta (C) and the descending aorta (D) for the geometry extracted from the data set of patient B. Figure 1. Key flow features of patient B Results and discussion We have implemented CFD models which are able to qualitatively assess the favourable or unfavourable impact of different approaches to ToF and CoA repairs on the characteristics of blood flow in the aorta and pulmonary arteries. An echo investigation protocol has been developed and successfully applied. CTA studies have been shown as feasible sources of geometry data in spite of the restriction on quality by the important requirement for low doses of radiation in paediatric patients. This project represents progress towards an advanced tool that may be broadly implemented in both well-resourced and minimally-resourced hospitals. Acknowledgement/Funding National Research Fund, British Heart Foundation, Newton Fund (UK MRC, South African Medical Research Council), University of Cape Town

A multi-view optical technique to extract the operating deflection shapes of a full vehicle using digital image correlation

Abstract The automotive and aerospace industries are increasingly using light-weight material to improve vehicle performance while reducing fuel consumption. However, using light-weight material can increase the air-borne and structure-borne noise. Thus, special attention needs to be paid in designing the vehicle body structure and evaluating its dynamics. In order to accomplish this, modal analysis is conventionally used. In this technique, the structure is excited using an impulse hammer or a mechanical shaker, and the response is measured using accelerometers. However, using contact-based transducers can mass-load the structure and can only provide data at a few discrete points. In the last decade, stereo-photogrammetry and three-dimensional digital-image correlation have received special attention in collecting operating data for structural analysis. These non-contact optical techniques provide a wealth of distributed data over the entire structure. However, the stereo-camera system is limited by the field of views of the cameras and can only measure the response on the parts of a structure for which cameras have lines of sight. Therefore, a single pair of DIC cameras may not be able to provide deformation data for an entire structure. A multi-view 3D DIC approach, however, can be used to predict the vibrational characteristics of a full vehicle. A pair of DIC cameras is passed over the entire vehicle to capture the deformation data of each field of view. The measured data includes the geometry and displacement data, which is mapped into a global coordinate system using 3D transformation matrices. The obtained data in the time domain for each field of view is transformed to the frequency domain using a Fast Fourier Transformation (FFT) to extract the operational deflection shapes and resonant frequencies for each field of view. The obtained deflection shapes are scaled and stitched in the frequency domain to extract the operating deflection shapes of the entire vehicle.

A fast computational model for wellbore pressure transients while perforating with dynamic underbalance

Perforations provide the critical production link between the reservoir and a cased well completion. Though perforating with shaped-charge jet penetrators is common practice today, they can leave behind tunnel debris and formation damage layers surrounding the perforations that significantly reduce well productivity. Perforating with a dynamic pressure underbalance has become a standard technique to provide better cleanup of debris and damage layers by enhancing the surge flow through tunnels (i.e., perforation cleanup). However, effective use of dynamic underbalance in practical perforating job design requires an understanding of three critical and interdependent processes: First, the generation of the underbalanced pressure transient, and how it depends on job design parameters such as wellbore geometry, gun configuration, and reservoir data; Second, how the magnitude and timing of the pressure underbalance drives the surge flow through perforation tunnels; Finally, the cleanup process itself, and how it depends on the generated surge flow. Though the latter two processes have received much attention from researchers over the past few decades, the design and optimization of the pressure underbalance itself has not. In this paper, a fast computational model for the generation of a dynamic underbalance is presented. The model is based on dominant physics. The effectiveness of this model is demonstrated by comparing results with pressure gage data obtained during API-RP 19B Section IV testing.

Numerical Investigation of Interaction of Counter Flow Jet and Hypersonic Capsule Flow Via Modified DsmcFoam

Abstract In this work, numerical investigation of interaction of counter flow jet and hypersonic re-entry capsule flow has been carried out through modification of DsmcFoam solver. The DsmcFoam modification includes implementation of variable soft sphere (VSS) collision model for more accurate collision model, adjustment of nonuniform initial condition for faster convergence and nonuniform boundary condition, calculation of local Knudsen number in postprocessing for adaptive grid generation, and implementation of different gas species for multigas flow interaction simulations. Therefore, the modified DsmcFoam can be used for investigation of the effect of counter flow jet on the vehicle aerodynamics and aerothermodynamics. New validation test cases from Von Karman gas dynamics facility (VKF) tunnel data of Apollo and blunt-cone re-entry geometries are studied via DsmcFoam in which a suitable agreement of results is observed compared to experimental data and also MONACO code computations. Also, the influence of counter flow jet has been presented, i.e., changing of bow shock configuration and its distance from the vehicle. Consequently, it is observed that by increasing counter flow jet velocity or density, reduction of the drag coefficient and heat flux on the vehicle will occur. Furthermore, variation of the velocity or density of counter flow jet leads to different jet-flow interaction patterns which are presented evidently.

Integration of Digital Elevation Model (DEM) and HEC-RAS Hydrodynamic Model for flood routing

The development of computer technology, especially the hydrodynamic modeling package, provides convenience in many things including flood modeling in the river. One of these modeling packages is HEC-RAS Hydrodynamic Model which can be used to simulate both steady flow and unsteady flow. On the other side, the development of Geographic Information System (GIS), is now rapidly evolving for a variety of purposes with a wider range of fields and scope, including the preparation of river geometry data based on Digital Elevation Model (DEM) in Triangulated Irregular Network (TIN) format as the input of the model. The aim of this study is to perform flood routing for determining the river capacity and for estimating the factors that cause floods by integrating TIN data into HEC-RAS Hydrodynamic Model, using Lantikadigo River in Central Sulawesi, Indonesia as a model. In this river, almost every year flooding occurs with fluctuating intensity of inundation. Integrating data is the process of synthesizing geometry data that is processed in the GIS environment as input for the HEC-RAS Model. Data integration provides the effectiveness of the use of simulation time due to input geometry data is done using import data facility when compared manually input geometry data. The results of the study show that the maximum water level of the 1-year return period has exceeded the river bank elevation both on the left and on the right side of the entire segment. The peak discharge of hydrograph for 1-year return period is 55.3 m3/s at the outlet of Lantikadigo Watershed. This means that the average channel capacity is far below the peak discharge. Based on simulation results it can be predicted that the cause of flooding in Lantikadigo River is due to morphological change of river geometry.

Perancangan Prototype LKS Materi Operasi Hitung Bilangan Bulat Untuk Peserta Didik Sekolah Dasar

Matematika merupakan ilmu universal yang mendasari perkembangan teknologi modern, mempunyai peranan penting dalam berbagai disiplin ilmu dan memajukan daya pikir manusia. Matematika perlu diberikan kepada semua peserta didik mulai dari sekolah dasar untuk membekali peserta didik dengan kemampuan berpikir logis, analitis, sistematis, kritis, kreatif, dan kemampuan bekerja sama. Tahapan-tahapan aspek yang berurutan dalam matematika yaitu bilangan, geometri dan pengukuran serta pengolahan data. Dari tahapan aspek yang disebutkan terlihat bahwasannya pokok bahasan bilangan merupakan tahapan awal yang harus dikuasai dalam matematika. Bilangan merupakan pokok bahasan dasar yang sangat penting dipahami oleh para peserta didik karena merupakan landasan untuk pokok-pokok bahasan lainnya. Salah satu bagian dari pokok bahasan bilangan ini adalah bilangan bulat. Untuk itu, penelitian ini bertujuan untuk mengembangkan bahan ajar berupa LKS materi operasi hitung bilangan bulat untuk peserta didik sekolah dasar. Penelitian ini merupakan tahap awal dari penelitian pengembangan. Subjek penelitian adalah peserta didik kelas IV SD Negeri 42 Pangkalpinang. Penelitian ini dilakukan tahap preliminary (persiapan) dan tahap formative evaluation ( self evaluation) yang menghasilkan prototipe pertama LKS materi operasi hitung bilangan bulat untuk peserta didik sekolah dasar.

A PCA-Based Framework for Determining Remotely Sensed Geological Surface Orientations and Their Statistical Quality.

The orientations of planar rock layers are fundamental to our understanding of structural geology and stratigraphy. Remote sensing platforms including satellites, unmanned aerial vehicles, and Light Detection and Ranging scanners are increasingly used to build three‐dimensional models of structural features on Earth and other planets. Remotely gathered orientation measurements are straightforward to calculate but subject to uncertainty inherited from input data, differences in viewing geometry, and the plane‐fitting process, complicating geological interpretation. Here, we improve upon the present state of the art by developing a generalized means for computing and reporting errors in strike‐dip measurements from remotely sensed data. We outline a general framework for representing the error space of uncertain orientations in Cartesian and spherical coordinates and develop a principal component analysis (PCA) regression method, which captures statistical errors independent of viewing geometry and input data structure. We also introduce graphical techniques to visualize the uniqueness and quality of orientation measurements and a process to increase statistical power by jointly fitting bedding planes under the assumption of parallel stratigraphy. These new techniques are validated by comparison of field‐gathered orientation measurements with those derived from minimally processed satellite imagery of the San Rafael Swell, Utah, and unmanned aerial vehicle imagery from the Naukluft Mountains, Namibia. We provide software packages supporting planar fitting and visualization of error distributions. This method increases the precision and comparability of structural measurements gathered using a new generation of remote sensing techniques.

An Unsupervised Learning Framework for Track Quality Index and Safety

Rail track geometry defect remains a primary cause of train accidents in the USA. With over $1 billion lost annually to geometry-related accidents, there is an urgent need to re-assess the analysis and treatment of geometry defects. The development of track quality index (TQI) takes a contracted view of track assessment by focusing only on quality without any safety consideration. Track geometry safety limits are set by Federal Railroad Administration based on raw track geometry data. Since different variations of track geometry parameters exist, there is a skepticism about the effectiveness of the current bipartite analytical approach of track quality and safety. These results into two maintenance regimes: regular and spot maintenance. This study aims to create a framework through which a hybrid index that combines both safety and quality can effectively eliminate costly spot maintenance practices. This index would be used to create a data-driven maintenance scheme that maximizes the time between two maintenance cycles and minimizes disruptions. This technical note describes the proposed framework for creating such an index using unsupervised machine learning.

Flood Inundation Mapping of Babai Basin using HEC-RAS & GIS

The main objective of this research is to prepare inundation map of a section of Babai Basin and to find out the inundated areas for different return periods. In order to achieve the objectives, Geographic Information System (GIS) and HEC-RAS along with HEC-GeoRAS extension were used as tools. Coordinates were used as primary parameter and were obtained from survey to generate geometric data such as Triangular Irregular Networks (TIN), streamline, river bank and flow paths. After importing the geometry data into HEC-RAS, hydraulic modelling was applied by using flow data as main input. As a result, the watershed area of the Babai basin has been successfully modelled and map showing the flooded areas along the Babai basin has been delineated. The flooded area was geometrically overlaid on the topographic map to outline the affected areas. The area under the influence of the flood were assessed which shows that about 49% of total inundated areas comprises farming land. Also a sensitivity analysis was performed to predict the change in percentage of flooded areas when Maning’s parameter was increased by 10% and when kept same in both banks and channel. However, differences in figure of inundated areas are insignificant to variations made in Maning’s n.