1,975 research outputs found

    Dynamic Body VSLAM with Semantic Constraints

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    Image based reconstruction of urban environments is a challenging problem that deals with optimization of large number of variables, and has several sources of errors like the presence of dynamic objects. Since most large scale approaches make the assumption of observing static scenes, dynamic objects are relegated to the noise modeling section of such systems. This is an approach of convenience since the RANSAC based framework used to compute most multiview geometric quantities for static scenes naturally confine dynamic objects to the class of outlier measurements. However, reconstructing dynamic objects along with the static environment helps us get a complete picture of an urban environment. Such understanding can then be used for important robotic tasks like path planning for autonomous navigation, obstacle tracking and avoidance, and other areas. In this paper, we propose a system for robust SLAM that works in both static and dynamic environments. To overcome the challenge of dynamic objects in the scene, we propose a new model to incorporate semantic constraints into the reconstruction algorithm. While some of these constraints are based on multi-layered dense CRFs trained over appearance as well as motion cues, other proposed constraints can be expressed as additional terms in the bundle adjustment optimization process that does iterative refinement of 3D structure and camera / object motion trajectories. We show results on the challenging KITTI urban dataset for accuracy of motion segmentation and reconstruction of the trajectory and shape of moving objects relative to ground truth. We are able to show average relative error reduction by a significant amount for moving object trajectory reconstruction relative to state-of-the-art methods like VISO 2, as well as standard bundle adjustment algorithms

    Effect of Out-Gassing on the Onset of Hypersonic Boundary Layer Transition

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    Prediction and control of the onset of transition and the associated variation in aerothermodynamic parameters in high-speed flows is key to optimize the performance and design of Thermal Protection Systems (TPS) of next-generation aerospace vehicles [1]. Boundary Layer Transition (BLT) characteristics can influence the surface heating budget determining the TPS thickness and consequently its weight penalty. Ablative heatshields are designed to alleviate the high heat flux at the surface through pyrolysis of their polymeric matrix and subsequent fiber ablation [2]. Pyrolysis leads to out-gassing and non-uniform ablation lead to surface roughness, both of which are known to influence the transition process. An ablator impacts BLT through three main routes: gas injecting into the boundary layer from the wall, changing the surface heat transfer due to wall-flow chemical reactions, and modifying surface roughness [3]. In preparation to Mars 2020 mission post-flight analysis, the predictive transition capability has been initiated toward hard-coupling porous material response analysis and aerothermal environment calculation

    Impulse Voltage Breakdown Strength vs. Temperature of Octafluoropropane (Ca Fa) Gas Exposed to Uniform and Non-uniform Fields

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    The purpose of my thesis is to investigate the impulse voltage breakdown strength of Octafluoropropane gas as a function of the temperature of the gas. The standard 1.5 x 40f4sec. positive polarity impulse waveshape was used in alt the tests. The investigation was made with and without a weak source of irradiation present near the eel I. Two types of electrode systems were used: three fourth inch sphere to grounded plane which represented a fairly uniform field, and a point to grounded plane representing a highly non-uniform field. The tests were carried out to room temperature to a temperature of 150°C. The impulse ratios of the gas was also plotted using some of the data from Roman\u27s thesis. Impulse Ratio is defined as the ratio of the impulse crest voltage strength and the crest value of 60 Hz one-minute voltage withstand test. It is a very important factor for designers from an insulation co-ordination point of view

    Effect of Structured Teaching Programme on Neonatal Resuscitation among the Staff Nurses of Selected Hospitals at Bhopal, Madhya Pradesh, India

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    The present study was conducted to assess the effectiveness of structured teaching programme on neonatal resuscitation among the staff nurses. An experimental design was chosen with pre-test and post-test of experimental and control group. The sample size was 60 registered staff nurses divided into two groups as 30 in experimental and 30 in control group. The tools used for conducting the study included demographic variables, self-structured questioner to assess knowledge of experimental and control group. The experimental group was given structured teaching programme and the control group was used for comparison only. The data were analyzed with the help of descriptive and inferential statistics. The study clearly shows that there was a significant gain in knowledge of staff nurses in experimental group with structured teaching programme which emphasizes neonatal resuscitation by the staff nurses. Therefore, the staff nurses can be benefited with structured teaching programme to improve knowledge on neonatal resuscitation

    Double Diffusive Mixed Convection in a Couple Stress Fluids with Variable Fluid Properties

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    Study of double diffusive mixed convection flow of a non-Newtonian couple stress fluid over a vertical heated plate in a sparsely packed porous medium with variable fluid properties has been investigated analytically and numerically. The governing non-linear partial differential equations are transformed into a system of ordinary differential equations using similarity transformation and then solved numerically using the shooting technique that involve Runge-Kutta-Fehlberg integration scheme and Newton-Raphson corrector method to obtain the non-dimensionalised velocity, temperature and concentration distributions. The Influence of non-dimensional governing parameters on velocity, temperature and concentration profiles along with friction factor, heat and mass transfer rates were discussed and presented through graphs and tables. Comparisons of the present results made with the existed results. We have found an excellent agreement with the existed results

    SOLAR POWERED THREE PHASE MOTOR FOR VARIOUS APPLICATIONS

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    The Power electronics plays a vital role in the conversion and control of the electrical power for various applications such as heating & lightning control, electrochemical processes, DC & AC electrical machine drives, electrical welding, active power line filtering, static var compensator and many more.The main aim of the paper is to analyze and design of a current fed push pull DC-DC boost converter to integrate three phase electric motor through inverter. The regulated output which is obtained by the developed converter is fed to a typical load side inverter, and then to the various loads. To analyze the CFPP DC-DC converter in different operating cycles. The hardware circuit will be designed to test for the required output.Among the existing DC/DC converters, current-fed push-pull (CFPP) converter is a better option owing to its voltage boosting, isolation and compact characteristics

    Effect of friction-welding parameters on the tensile strength of AA6063 with dissimilar joints

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    In this paper, the effect of welding parameters of rotary friction welding between AA6063 and AISI4130 and AA6063 and Copper are investigated. The major influencing parameters considered are upset pressure, friction time and friction pressure of friction welding are considered for this study. The Taguchi’s design of experiments was conducted for the influencing parameters and their levels. The tensile test experimentation was carried out and the results of the AA6063 and AISI4130 and AA6063 and Copper are compared. The ultimate tensile strength of AA6063-AISI4130 joint and AA6063-Copper joint was improved by increasing upset pressure up to 97MPa with FP of 71 MPa and FT of 4 sec. On the side of AA6063, intermetallic compounds have formed, as seen in SEM micrographs. Microcracks are forming on the side of AA6063 and propagates along the grain boundaries. The effect of the influencing parameters on the tensile strength of the dissimilar joints are studied using the Taguchi’s DOE and ANOVA. From the outcomes it is observed that the friction pressure influence more on the strength of the AA6063 dissimilar joints

    Risk analaysis of ethanol blending fuel in refinery industry using event tree analysis and Topsis method

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    Chemicals have always posed risks including fire, explosion, and the release of harmful substances in process industries like the Petroleum Industry. The occurrence of such catastrophes has a significant impact on the resources for finances and daily living. In this research paper, the major safety-related causes and effects are identified through event tree analysis based on accidents and incidents while using ethanol as fuel. For this purpose, the accident and incident data collected so far while using ethanol in the fuel industry, detailed information about ethanol, and even tree analysis. The event tree analysis (ETA) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) analysis method is utilized to Identifying an initiating event of interest of accident. The event tree\u27s structure also aids the analyst in identifying the locations where additional protocols or safety measures are required to mitigate accidents or lower their frequency
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