178 research outputs found
Polarimetric radar modeling of mixtures of precipitation particles
No full textWith the recent advances of dual-polarized radar techniques in meteorology it is now possible to deduce precipitation microphysical characteristics in far more detail than possible with reflectivity measurements alone. Radar parameters such as differential reflectivity and differential phase between horizontal and vertical polarizations have been studied in detail as well as linear depolarization ratio, copolar correlation coefficient, and backscatter differential phase. While these parameters can be linked to certain microphysical properties of specific classes of precipitation such as raindrops or hail, very little study has been directed at the practically important cases of mixtures of different types of precipitation particles such as rain, hail, graupel, ice crystals, and snow. Each type can have different size, shape, orientation, and dielectric constant distributions. The treatment here is rigorous and is based on the Mueller matrix formulation. Radar parameters are derived from the averaged Mueller matrix computations. Careful consideration is given to the orientation and size distributions of the different particle types. After calculating single particle scattering characteristics, some simple two-component mixtures such as rain/hail and ice crystals/snow are considered. Finally, a 2D numerical cloud model is used to simulate the rain, hail/graupel, and snow fields of an evolving convective storm from which the radar parameters are derived for the initial, peak, and dissipating stages of the storm. Model computations are performed at C and S-band frequencies.This work was supported by the FAA under Contract DTFA01-90-Z-02005 and the National Science Foundation under Contract ATM-9214864. The work of R. Raghavan was also supported by NASA through USRA under Contract NAS8-37140. The National Center for Atmospheric Research is sponsored by the National Science Foundation
Project Management Learnings from Ramayana
No full textRamayana is the first Indian Epic also known as Adhi Kavya comprising 24000 shlokas, grouped in 500 sargaswhich are divided over 7 kandas. The first author of Ramayana, written in Sanskrit, is Maharishi Valmiki. These authors have discovered multiple dimensions and implications of Ramayana in diverse fields like Management, Philosophy, Spirituality, Literature, Indian Mythology, etc. There are many teachings from this epic that can be applied in today's management-life in areas such as Project Management, Strategic Management, Leadership, Human Resource Management, and the like. In Ramayana, after the evil-spirited Ravana abducted Goddess Sita, Lord Rama who is in search of Goddess Sita, along with his brother, Lakshmana finds Lord Hanuman, a noble monkey, who played a predominant role in search of Goddess Sita and destruction of Ravana, the king of Lanka. After finding the whereabouts of Goddess Sita, they prepared for a war with Ravana to bring her back to Ayodhya. They also prepared for the Coronation of Lord Rama; so that" the Prince in exile becomes the King of Ayodhya". Objective: The application of Agile Project Management at the time of searching Goddess Sita in Ramayana. Methodology: Agile Project Management methodology is used in this research study, which has four main stages: Project Initiation, Project Planning, Project Execution, and Project Closure The research study tries to understand in detail how Ramayana's knowledge-repository is integrated into the modern-day Agile Project Management Methodology. Results: Valmiki Ramayana is extremely wealthy in portraying multiple examples of Project Management methodologies, synthesizing of Agile Project Methodologies from Ramayana, and application of Project Management to modern-day Projects. Implications: The results from this article can be applied to today's management life like – Project Management, Strategic Management, Leadership, and Human Resource Management
Patentopia: A multi-stage patent extraction platform with disambiguation for certain semantic challenges
No full textBibliographic name disambiguation is an major semantic challenge, but critical to social sciences studies of important intellectual assets. Here we contribute to innovation research in several ways. We show a significant synonym problem in author names and discuss how a pre-processing heuristic step standardizing name variants helps, but homonyms generated with Chinese names are particularly difficult to resolve and manifest in an associated location list. Here we identify a new phenomenon of "onomastic profusion," the frequent use of certain words in firm names for semantic reasons that can confound disambiguation clustering algorithms. We illustrate these concerns with Patentopia, our customized platform accessing the PatentsView portal for the United States Patent and Trademark Office database and available for free academic use. This multi-stage system uses heuristics in concert with the PatentsView clustering process and reports meta-data to further assist analysis. As highly relevant use cases, we illustrate system performance with data derived from two important public innovation programs, I-Corps and Small Business Innovation Research (SBIR), and we close with implications for bibliometric analysis of current patent data.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Delft Centre for Entrepreneurshi
Nonzero-sum Stochastic Games
No full textThis paper treats of stochastic games. We focus on nonzero-sum games and provide a detailed survey of selected recent results. In Section 1, we consider stochastic Markov games. A correlation of strategies of the players, involving ``public signals'', is described, and a correlated equilibrium theorem proved recently by Nowak and Raghavan for discounted stochastic games with general state space is presented. We also report an extension of this result to a class of undiscounted stochastic games, satisfying some uniform ergodicity condition. Stopping games are related to stochastic Markov games. In Section 2, we describe a version of Dynkin's game related to observation of a Markov process with random assignment mechanism of states to the players. Some recent contributions of the second author in this area are reported. The paper also contains a brief overview of the theory of nonzero-sum stochastic games and stopping games which is very far from being complete.average payoff stochastic games, correlated stationary equilibria, nonzero-sum games, stopping time, stopping games
A comparative study on BEM solvers for Wave Energy Converters
No full textWave Energy Converters (WECs) are expected to significantly contribute to the energy transition; however, this depends on their interactions with the resource. Calculating the power generated by WECs depends heavily on the accurate modelling of wave-structure interactions. The Boundary Element Method (BEM) based on the potential flow theory has yielded accurate results at low computational costs when compared to complex Computational Fluid Dynamics (CFD) methods. Hydrodynamic Analysis of Marine Structures (HAMS), a recently developed open-source BEM frequency domain solver, originally was created for large marine structures. To date it has only been applied to single WECs with spherical/cylindrical geometries. HAMS offers unique advantages through its efficient removal of irregular frequencies and lower computational costs. This paper aims to compare hydrodynamic coefficients, exciting forces, Response Amplitude Operators (RAOs) and computational costs between HAMS,WAMIT, and NEMOH for a cylindrical point absorber and an oscillating surge WEC, extending the currently limited WECs application in HAMS.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Offshore Engineerin
Detection of Cognitive Features from Web Resources in Support of Cultural Modeling and Analysis
No full textThe World Wide Web serves as a valuable source of culture-relevant information, which can be used to support cultural modeling and analysis activities. Part of the challenge in exploiting the Web as a source of culture-relevant information relates to the need to detect and extract information about beliefs, attitudes, and values from a variety of different resources. The Web thus features a rich variety of information resources, and these are seldom categorized with respect to the dimensions in which cultural analysts are interested. Exploiting the Web as a source of culture-relevant information therefore requires techniques and approaches that enable cultural analysts to extract relevant information and organize extracted content in various ways. In this paper, we outline an approach to assist cultural analysts in the extraction and organization of relevant information. We show techniques that can be used to extract information about the attitudes, beliefs, and values of individuals, and how this data can, in turn, be used to support cultural modeling and analysis
Compensation through Writ Petitions: An Analysis of Case Law
No full textIn this article, the author has tried to find out the trend of the Supreme Court in the area of Compensatory Jurisprudence. The author has noted all the decisions in a manner which will help subsequent researchers to get their fundamental materials
Hybrid Method for Soil-Structure Interaction for Offshore Wind Turbine Monopile Foundations
No full textThe Offshore wind industry is constantly expanding and one of the key cost drivers is the offshore wind turbine support structure. The foundation accounts for up to 35 % of the total installation cost of the wind turbine. The monopile foundations are the most commonly used support structure with diameters up to 6m and Embedded length/depth (L/D)<7. Proper modeling of the soil-structure interaction (SSI) is important for safe and efficient design. With the introduction of large diameter rigid monopile foundations, the applicability of the current design standard is in question. The current industry standard model for SSI for laterally loaded monopiles is the Winkler foundation model. In this model, the soil is idealized as a row of one dimensional discrete springs spanning along the beam. The stiffness of these springs is obtained using empirically derived p-y curves, which gives the relation between the soil-pressure (p) and deflection (y). The p-y method describes the construction of the p-y curves for any arbitrary set of soil parameters. This method has been applied in the oil and gas industry and is based on field tests conducted on slender piles with diameter 2m. Various studies on the applicability of the model have shown to give erroneous results for large diameter monopiles. Since the soil is idealized as a row of discrete (local) springs, it neglects the continuous (non-local) nature of soil. Additionally, monopiles with L/D <7 exhibit a more rigid behavior and hence industry standard assumptions for laterally loaded piles with respect to vertical tangent criteria and 'zero-toe-kick' do not hold on. A plane strain semi-analytical model is developed which considers the continuous (non-local) nature of soil as well as the soil below the pile toe/tip, which could be significant to the dynamic behavior of the monopile foundations. In this approach, the pile is modeled as an elastic rectangular plate which is discretized using modified Euler-Bernoulli beam elements. and the soil is modeled as an elastic continuum waveguide. The two entities are combined via the discretized interface. Assuming wave motion in soil, semi-analytical solutions satisfying homogeneous and inhomogeneous boundary conditions are obtained for the waveguide, which are used to derive the frequency dependent soil stiffness matrices at the interface. These are then coupled to the plate. For the current study, the L/D ratio of the plate is restricted to the flexible regime, due to the availability of a comparable reference solution in this regime. It is shown that, with L/D ratio of 12.5 already, the dynamic behavior of the plate is sensitive to the soil below the tip. Therefore, with smaller L/D ratios, it is expected that the tip will have a significant influence on the dynamic behavior of the pile
A Sensor Data Fusion Algorithm for Human Motion Estimation
No full textIn the elderly population, falls are one of the major causes of injuries. Fall detection algorithms for wearable devices in the literature were found to focus on differentiating Activities of Daily Living (ADL) from falls, rather than on early fall detection and prevention before impact. This thesis work was aimed at providing accurate estimates of human motion parameters like translational velocities of the center of mass, so as to aid early fall detection algorithms in the future. An algorithm which fuses visual and inertial data obtained from a sensor setup consisting of a pair of cameras and an Inertial Measurement Unit (IMU) was developed. An Extended Kalman Filter (EKF) framework was used for sensor data fusion. A neural network was trained to map motions of interesting points or features obtained from image processing, to actual motion of the sensor setup attached to the hip of a person. This neural network provided the correction term to the EKF in the form of 3 dimensional(3D) translational velocities which is an important motion parameter for the detection of falls. First, this algorithm was trained and tested for hand-held sensor setup motions. Acceptable velocity tracking was observed for slow motions. Then the algorithm was trained and tested on motions of a test subject. The accuracy of estimation of 3D translation velocities and in particular the vertical component of the 3D velocity was studied for two distinct sets of activities or motions namely the walking motion and the sitting down/standing up motion. It is shown that the combination of the EKF and the neural network is capable of reacting and tracking the velocities for the sitting down/standing up motion.Mechanical, Maritime and Materials EngineeringDelft Center for Systems and Contro
Recommended from our members
Compensation through Writ Petitions: An Analysis of Case Law
No full textIn this article, the author has tried to find out the trend of the Supreme Court in the area of Compensatory Jurisprudence. The author has noted all the decisions in a manner which will help subsequent researchers to get their fundamental materials
- …
