2,203 research outputs found

    Bounds on Parameters in Dynamic Discrete Choice Models

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    Identification of dynamic nonlinear panel data models is an important and delicate problem in econometrics. In this paper we provide insights that shed light on the identification of parameters of some commonly used models. Using this insight, we are able to show through simple calculations that point identification often fails in these models. On the other hand, these calculations also suggest that the model restricts the parameter to lie in a region that is very small in many cases, and the failure of point identification may therefore be of little practical importance in those cases. Although the emphasis is on identification, our techniques are constructive in that they can easily form the basis for consistent estimates of the identified sets.

    Luminescence dating and mineralogical investigations of bricks from erikli basilica in Stratonikeia ancient city (SW-Turkey)

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    Stratonikeia is one of the oldest settlements in southwestern Anatolia and at the same time significant for an understanding of the Hellenistic period. Archaeological records of Stratonikeia date back to around 2000 BC. This study provides new information not only about luminescence age but also about mineralo-petrographic, geochemical characteristics of bricks taken from Erikli Basilica in Stratonikeia (Turkey). In this study, mineralogical data of TL and OSL dating of two bricks and two sediment samples will be presented. The bricks have highly similar mineralogical composition, consisting mainly of quartz and muscovite. These results are supported by XRD studies. In order to perform the thermoluminescence (TL) and optically stimulated luminescence (OSL) dating, the equivalent dose (ED) and the annual dose (AD) of the samples were determined using different estimation techniques. The TL ages of bricks are determined to be 1189±89 and 576±40 years. The IRSL ages of the bricks are determined to be 1167±85 years and 545±50 years. Additionally, supporting the TL and IRSL ages, the OSL quartz ages of the two sediments obtained from the top of the layer under the floor are discovered to be about 1100 years. Mineralo-petrographic, geochemical, dating and archaeological studies have revealed that the age of bricks is different from each other. Furthermore, Erikli Basillica was built in bricks, consisting of raw materials taken from different quarries in different periods. Within the framework, the first report of the experimental approach has been published from Stratonikeia archaeological site located in Muğla, Agean Anatolia. © 2018 MAA Open Access. Printed in Greece. All rights reserved

    Optimal trajectory generation in ocean flows

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    In this paper it is shown that Lagrangian Coherent Structures (LCS) are useful in determining near optimal trajectories for autonomous underwater gliders in a dynamic ocean environment. This opens the opportunity for optimal path planning of autonomous underwater vehicles by studying the global flow geometry via dynamical systems methods. Optimal glider paths were computed for a 2-dimensional kinematic model of an end-point glider problem. Numerical solutions to the optimal control problem were obtained using Nonlinear Trajectory Generation (NTG) software. The resulting solution is compared to corresponding results on LCS obtained using the Direct Lyapunov Exponent method. The velocity data used for these computations was obtained from measurements taken in August, 2000, by HF-Radar stations located around Monterey Bay, CA

    E-CITY KNOWWARE: KNOWLEDGE MIDDLEWARE FOR COORDINATED MANAGEMENT OF SUSTAINABLE CITIES

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    The realization of e-city is a necessary component for achieving the green city. This paper outlines a vision for an e-city platform that is based on knowledge brokerage in the green city. The proposed platform will be a venue for creating dynamic virtual organizations to harness collective intelligence of knowledge hubs to analyze and manage sustainability knowledge in urban areas. Knowledge assets of participating organizations will be presented in three dimensions: process structures, human profile and software systems. These three facets of knowledge will be accessible and viewable through a self-describing mechanism. Cities can post their geospatial and real-time data on the net. Relevant environmental and energy-use data will be extracted using topic maps and data extraction services. Local decision makers can synchronize work processes (from participating hubs) to create an integrated workflow for a new ad hoc virtual organization to collaboratively analyze the multifaceted nature of sustainable decision making. An e-city platform is envisioned in this paper that will be realized through intelligent, agent-like, domain-specific middleware (KnowWare). Through triangulation between people, software and processes, these KnowWare will discover, negotiate, integrate, reason and communicate knowledge (related to energy and environment) from across organizations to the right person at the right time. KnowWare is fundamentally, a portal of social semantic services that resides on a cloud computing infrastructure. Knowware exploits thee main tools: 1) existing ontologies to represent knowledge in a semantic manner, 2) topic maps to profile sources of knowledge and match these to the complex needs of sustainability analysis, 3) domain-specific middleware for knowledge integration and reasoning
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