On Chase Termination Beyond Stratification

We study the termination problem of the chase algorithm, a central tool in various database problems such as the constraint implication problem, Conjunctive Query optimization, rewriting queries using views, data exchange, and data integration. The basic idea of the chase is, given a database instance and a set of constraints as input, to fix constraint violations in the database instance. It is well-known that, for an arbitrary set of constraints, the chase does not necessarily terminate (in general, it is even undecidable if it does or not). Addressing this issue, we review the limitations of existing sufficient termination conditions for the chase and develop new techniques that allow us to establish weaker sufficient conditions. In particular, we introduce two novel termination conditions called safety and inductive restriction, and use them to define the so-called T-hierarchy of termination conditions. We then study the interrelations of our termination conditions with previous conditions and the complexity of checking our conditions. This analysis leads to an algorithm that checks membership in a level of the T-hierarchy and accounts for the complexity of termination conditions. As another contribution, we study the problem of data-dependent chase termination and present sufficient termination conditions w.r.t. fixed instances. They might guarantee termination although the chase does not terminate in the general case. As an application of our techniques beyond those already mentioned, we transfer our results into the field of query answering over knowledge bases where the chase on the underlying database may not terminate, making existing algorithms applicable to broader classes of constraints.Comment: Technical Report of VLDB 2009 conference versio

EXPERIMENTAL INJECTION STRATEGY FOR SURFACTANT FLOODING ENHANCED BY BRANCHED ALCOHOL ADDITIVE

There are few limitations in using surfactant/co-surfactant such as the interfacial activity, adsorption and ionic equilibria which can be control by manipulating the formulation of the injected solution. Other limitations which can be controlled by injection strategy were chromatographic effect, mobility control, flow diversion by precipitates and emulsification. By using the optimum formulation, the first part of the limitations can be reduced. And the second part of limitations can be overcome by investigating the best or optimum method for injecting optimum formulation. The objective of this study is to find the optimum injection strategy of a well formulated surfactant and co-surfactant in enhancing residual oil recovery. Already several methods had been proposed for surfactant / co-surfactant flooding, in this study, topic will be narrowed to, to find the best injection strategy for surfactant flooding with branched alcohol as co-surfactant. Result will be presented on the percentage of residual oil recovered by using different method of injection. Below are the injection strategies which are to be tested. Injection strategies which to be study are: 1) Surfactant and branched alcohol mixed in single formation then followed by chase water 2) Surfactant followed by branched alcohol then followed by chase water 3) Branched alcohol followed by surfactant then followed by chase water Methodology used in this study is based on coreflooding experiment. Briefly, the experiment will be conducted using three (3) Barea cores. Each core first preflooded with synthetic brine at optimum salinity and hardness to saturate the core with brine. Core then will be flooded with crude oil to displace the brine. Then, core will undergo water flooding to displace the crude oil injected to the core. Residual oil saturation then can be calculated from the volume of water produced after the water flood, volume of oil produced during the water flood and pore volume of the core. All the cores then will be injected with chemicals using different methods. The effluent recovered will be measure and the efficiency of each method will be calculated

Autonomous docking ground demonstration (category 3)

The NASA Johnson Space Center (JSC) is involved in the development of an autonomous docking ground demonstration. The demonstration combines the technologies, expertise and facilities of the JSC Tracking and Communications Division (EE), Structures and Mechanics Division (ES), and the Navigation, Guidance and Control Division (EG) and their supporting contractors. The autonomous docking ground demonstration is an evaluation of the capabilities of the laser sensor system to support the docking phase (12ft to contact) when operated in conjunction with the Guidance, Navigation and Control Software. The docking mechanism being used was developed for the Apollo Soyuz Test Program. This demonstration will be conducted using the Six-Degrees of Freedom (6-DOF) Dynamic Test System (DTS). The DTS environment simulates the Space Station Freedom as the stationary or target vehicle and the Orbiter as the active or chase vehicle. For this demonstration the laser sensor will be mounted on the target vehicle and the retroreflectors on the chase vehicle. This arrangement was used to prevent potential damage to the laser. The sensor system. GN&C and 6-DOF DTS will be operated closed-loop. Initial condition to simulate vehicle misalignments, translational and rotational, will be introduced within the constraints of the systems involved. Detailed description of each of the demonstration components (e.g., Sensor System, GN&C, 6-DOF DTS and supporting computer configuration) including their capabilities and limitations will be discussed. A demonstration architecture drawing and photographs of the test configuration will be presented

Does Going Green Mean Losing Green? Bank of America vs JPMorgan Chase

This research thesis is an investigation into whether companies implementing a “going green” strategy will compromise their financial performance. The primary focus was on two large financial institutions, one clearly committed to going green and the other less interested in doing so: Bank of America and JPMorgan Chase. The assessment centered on specific financial measurement points for the fiscal years of 2010 and 2011. Concern for health and wellbeing of the earth is growing exponentially, however, in order to sustain the movement it is imperative that companies join the green initiatives. Nevertheless, companies must achieve specific thresholds of financial performance and the question is whether “green initiatives” compromise these critical points of performance. If they do, corporate management may lose shareholder support and be forced to change strategies. This study determined that Bank of America, the “Going Green” firm did not perform as well as JP Morgan Chase in multiple measurement categories. However, it did maintain a stronger relationship between debt and assets, suggesting the potential for future improved performance. This thesis also reveals a comprehensive discussion of findings, details study limitations, and offers suggestions for future research

An application of the chase algorithm to multiuser detection

With various added services in future wireless communication systems, the demand for fast and highly reliable data transmissions is continuously increasing. Multiple access interference (MAI) in direct-sequence code division multiple access (DS-CDMA) and constrained capacity in single-input single-output (SISO) are the major obstacles to achieve this purpose. For overcoming these limitations, the use of multiuser detection (MUD) and multiple-input multiple-output (MIMO) is necessary. In the area of error control coding, the Chase algorithm, which takes advantage of the different reliabilities of the received symbols and focuses on correcting the error in the weakest symbols, can achieve a near maximum-likelihood (ML) performance and with significant complexity reduction. In this thesis, we discuss the application of the Chase algorithm in multiuser detectors for the SISO-CDMA and MIMO-CDMA systems. In the SISO-CDMA systems, we develop a parallel interference cancellation (PIC) scheme using the Chase algorithm after the matched filters (MFs). This scheme is called Chase-PIC. Instead of optimizing the weight of each user as most of PIC detectors do, this detector provides a new optimizing approach right after the MFs. Based on the analysis of the complexity and performance over the flat and frequency-selective Rayleigh fading channels, we also propose a new Chase based multistage PIC that uses the normalized least-mean-square (NLMS) algorithm at the earlier stages and the Chase algorithm at the later stages. This proposed scheme can achieve a better performance than NLMS-PIC but with less complexity. In the MIMO-CDMA systems, we proposed a new Chase based multiuser detector over the flat Rayleigh fading channels. This detector focuses on correcting the error of the weakest detected symbol in the layered space-time multiuser detector (LAST-MUD). Compared to another Chase based detector, B-Chase, the proposed scheme has less complexity but with the tendency of achieving better performance at high signal-to-noise ratio (SNR)

Pattern transition in spacecraft formation flying using bifurcating potential field

Many new and exciting space mission concepts have developed around spacecraft formation flying, allowing for autonomous distributed systems that can be robust, scalable and flexible. This paper considers the development of a new methodology for the control of multiple spacecraft. Based on the artificial potential function method, research in this area is extended by considering the new approach of using bifurcation theory as a means of controlling the transition between different formations. For real, safety or mission critical applications it is important to ensure that desired behaviours will occur. Through dynamical systems theory, this paper also aims to provide a step in replacing traditional algorithm validation with mathematical proof, supported through simulation. This is achieved by determining the non-linear stability properties of the system, thus proving the existence or not of desired behaviours. Practical considerations such as the issue of actuator saturation and communication limitations are addressed, with the development of a new bounded control law based on bifurcating potential fields providing the key contribution of this paper. To illustrate spacecraft formation flying using the new methodology formation patterns are considered in low-Earth-orbit utilising the Clohessy-Wiltshire relative linearised equations of motion. It is shown that a formation of spacecraft can be driven safely onto equally spaced projected circular orbits, autonomously reconfiguring between them, whilst satisfying constraints made regarding each spacecraft

Discrimination nets, production systems and semantic networks: Elements of a unified framework

A number of formalisms have been used in cognitive science to account for cognition in general and learning in particular. While this variety denotes a healthy state of theoretical development, it somewhat hampers communication between researchers championing different approaches and makes comparison between theories difficult. In addition, it has the consequence that researchers tend to study cognitive phenomena best suited to their favorite formalism. It is therefore desirable to propose frameworks which span traditional formalisms. In this paper, we pursue two goals: first, to show how three (symbolic) formalisms widely used in theorizing about and in simulating human cognition—discrimination nets, semantic networks and production systems—may be used in a single, conceptually unified framework; and second to show how this framework can be used to develop a comprehensive theory of learning. Within this theory, learning is construed as (a) developing perceptual and conceptual discrimination nets, (b) adding semantic links, and (c) creating productions. We start by giving a brief description of each of these formalisms; we then describe a theoretical framework that incorporates the three formalisms, and show how these may coexist. Throughout this description, examples from chess, a highly studied field of expertise and a classical object of study in cognitive science, will be provided. These examples will illustrate how the framework can be worked out into a more detailed cognitive theory. Finally, we draw some theoretical consequences of the framework proposed here

Foundations in Wisconsin: A Directory [30th ed. 2011]

The 2011 edition of Foundations in Wisconsin marks the 30th production of the print directory and the 11th year of the online version (www.wifoundations.org). The directory is designed as a research tool for grantseekers interested in locating information on private, corporate, and community foundations registered in Wisconsin. Each entry in this new edition has been updated or reviewed to provide the most current information available. Most of the data was drawn from IRS 990-PF tax returns filed by the foundations. Additional information was obtained from surveys, foundation Web sites, annual reports, and newsletters. While the national economic downturn has had a negative effect on Wisconsin foundations the past two years, there are some positive signs of recovery. The total number of active grantmaking foundations increased to a record high 1,324 (with 67 new foundations identified), and the total assets increased by 11% over last year to $6.2 billion. However, total grants fell to$458 million, a 3% decrease from last year.https://epublications.marquette.edu/lib_fiw/1006/thumbnail.jp