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Analysis of Signature Generation Schemes for Multiterm Queries In Linear Hashing with Superimposed Signatures
Get PDFSignature files provide efficient retrieval of data by reflecting the essence of the data objects into bit patterns. Our analysis explores the performance of three superimposed signature generation schemes as they are applied to a dynamic signature file organization based on linear hashing: Linear
Hashing with Superimposed Signatures (LHSS). The first scheme (SM) allows all terms set the same number of bits whereas the second and third schemes (MMS aid MMM) emphasize the terms with high discriminatory power. In addition, MMM considers the probability distribution of the number of query terms. The main contribution of the study is a detailed analysis of LHSS in multiterm query environments by incorporating the term discrimination values based on document and query frequencies. The approach of the study can also be extended to other signature file access methods based on partitioning. The
derivation of the performance evaluation formulas, the simulation results based on these formulas for various experimental settings, and the implementation results based on INSPEC and NPL text databases are provided. Results indicate that MMM and MMS outperform SM in all cases in terms of access savings, especially when terms become more distinctive. MMM slightly outperforms MMS in high weight and low weight query cases. The performance gap among all three schemes decreases as the database size increases, and as the signature size increases the performances of MMM and MMS decrease and converge
to that of the SM scheme when the hashing level is fixed
Investigation of Programming Languages for an Automated Manufacturing System
Get PDFThis paper is an investigation of alternative programming languages for use in manufacturing control applications. After reviewing several types of languages, two alternative languages for programming the flexible manufacturing cell in Miami University's Manufacturing Engineering Department are investigated. One language, called Cell Programming Language (CPL), is an object-like high level language developed at Miami
University. The other is Relay Ladder Logic (RLL) which is the
predominant language used in industry to program programmable logic controllers. An RLL program that is equivalent to an existing CPL program was developed for this purpose
A System Dynamics Model For Evaluating Investment Strategies for Agriculture Development
Get PDFThis paper presents a System Dynamics model to analyze the
consequences of investments in agriculture. The data is taken
from the various case studies of agriculture in India and is used as an example in the simulation model. A number of investment strategies are simulated to see the performence of the overall system. Some results are presented from the simulation providing insight into the intricacies of the system variables which may be used as guidelines for investing large funds in agro-projects to maximise the benefits and to reduce the undesired consequences. The model can be used to study the effects of changes in one or more controllable variables in the performance of the system. It provides insight into the system variables which are important in making the planning a success and to optimize the profits from the investments.
The paper describes in detail the system dynamics flow
diagram of the agriculture system model, the factors which are
important for investments to be profitable
A System Dynamics Model for Automation
Get PDFA system dynamics model is presented in this paper along with the results of simulation of some policies and their consequences automation. The automation seems to be the answer for faster growth and development throughout the world whether or not there is excessive labor or its shortage in a nation. Higher productivity, lower costs, better quality of products and services, remaining competitive and new innovations are benefits of automation and they are very important factors in
industrialization and as well as in sustaining the jobs in the long run. Very often, particularly in the developing countries, the politicians either exploit or in most cases misunderstand the total effects of automation and computerization. In India, for example, computerization of even very important services like airlines and trail reservations, insurance and banking have suffered due to political decisions for two decades. Only recently they have realized their mistakes and are trying to catch up. This simple system dynamics model can be easily used for systems analysis to study the effects of automation and thus can help in making strategic decisions in automation and policy guidelines formulations
Development of the Advanced Bi-Lingual Reading Assistant (ABRA) And Authorizing System (ABRA-AS)
Get PDFTwo programs were created to fulfill a contract with the German, Russian, and East Asian Language Department at Miami University. These programs, Advanced Bilingual Reading Assistant (ABRA) and Advanced Bi-lingual Reading Assistant -
Authoring System (ABRA-AS), create a teaching system designed to implement a "reading strategies" approach to teaching German. ABRA is a reading program where a student reads a gven text several times, each time in greater detail. At each level
highlighted words or phrases to which the student can obtain translation help. Each level also has comprehension questions. ABRA-AS is the authoring system which creates the levels, the highlights and definitions, and question and answers for the articles read by the ABRA program. Although this program has been written specifically for this project, it may have uses outside the foreign language classroom
A Floating Vertical TEC Ionosphere Delay Correction Algorithm for Single Frequency GPS Receivers
Get PDFThis paper presents an innovative method to mitigate ionosphere delay error for single frequency receivers. Traditional approach to ionosphere delay correction is carried out through modeling the total electron content (TEC) along each satellite signal path. Because of the large deviation of the TEC during different times of the day, season, and solar cycle from any mean measurements, the ionosphere delay error has always been the dominant error factor in signal frequency receivers. In our method, we allow a reference vertical TEC to â floatâ or to remain as an unknown in the range equation. The TEC along each satellite signal path is modeled as having its own vertical TEC whose major component is the reference vertical TEC with additional contributions from the TEC spatial derivatives. The TEC spatial derivatives can be modeled using existing ionosphere models, services that provide ionosphere measurements, or even better, the ionosphere correction algorithm (ICA) coefficients which are part of the navigation message. By having the reference vertical TEC as an additional unknown in the range equations, a minimum of five satellites is required to obtain the receiver position. As a byproduct of the range equation solution, we also solve for the reference vertical TEC which can be a convenient and inexpensive way to provide information on the ionosphere. The paper describes the detailed algorithm and simulation studies that demonstrate order of magnitude improvement in ionosphere error correction using this method over the conventional method
Case Study of Mesospheric Gravity Wave Momentum Flux and Dynamical Instability Using the Arecibo Dual Beam Incoherent Scatter Radar
Get PDFWe report the first observation of gravity wave momentum flux in the mesosphere using the dual-beam Arecibo incoherent scatter radar (ISR). Quasimonochromatic waves were observed throughout the daytime of July 28, 2001 in the altitude range of 65â 85 km. The largest wave speed was about 100 m/s and the dominant period was about 15 min. Instability, as indicated by the Richardson number, occurred at several altitudes, most dramatically at 77 and 81 kilometers. The zonal momentum flux is found to change sign at altitudes where dynamical instability occurs. No significant gravity waves were observed in the region having an eastward background wind, while they were ubiquitous when the background wind was westward. Citation: Zhou, Q., and Y. T. Morton (2006), A case study of mesospheric gravity wave momentum flux and dynamical instability using the Arecibo dual beam incoherent scatter radar, Geophys. Res. Lett., 33, L10802, doi:10.1029/ 2005GL025608
Software Approach to Access UWB Interference on GPS Receivers
Get PDFEver since the FCC approved the use of UWB devices in commercial and federal bands, various agencies whose operations and/or products rely on the integrity of signals within certain â restrictedâ radio frequency hands have voiced concerns over the potential impact of the UWB interference. GPS signals are among these â restrictedâ bands. Several groups in the GPS community have conducted experimental studies concerning the impact of UWB interference on the performance of various grades of commercial and aviation GPS receivers. In this paper, we present a software approach to simulate and evaluate UWB interference on GPS receivers. The software approach provides greater flexibility in the design of testing scenarios, such as the inclusion of a large number of aggregated UWB devices, the generation of new UWB signals and modulation schemes, and the possibility of extending the study to new GPS signals. The paper will discuss a general framework for developing algorithms to evaluate UWB and GPS interference under a wide variety of hardware and software conditions. This framework consists of three classes of components: Input, Processing, and Analysis. The input components are responsible for the generation of UWB signal waveforms and modulation schemes, and GPS signals. The processing components include a simulated model of GPS RF front end and software implementation of GPS processing blocks, such as acquisition, tracking, and post-processing. The Analysis components focus on the study of specsic receiver processing component outputs. Both real and simulated UWB signals can he used in the study. The real UWB signals are primarily used to validate the simulation procedure, whereas the simulated UWB signals are used to allow the immediate incorporation of new UWB waveforms and modulations in the evaluations. This paper will present details of the software components developed and the preliminary results achieve
Graphical User Interface Environment for Developing Workcell Control Programs
Get PDFA forms-based development environment for writing manufacturing
workcell programs is described. The environment is a Microsoft Windows application that allows a programmer to describe a sequence of operations and associated preconditions to control a workcell by filling in forms. The environment then generates code to be loaded into a controller. Currently, the environment generates a language called Cell Programming Language (CPL),
which is a workcell programming language used at Miami University. The aim of the environment is to provide an easier-to-use environment for developing workcell control software