Integrity constraints in deductive databases

A deductive database is a logic program that generalises the concept of a relational database. Integrity constraints are properties that the data of a database are required to satisfy and in the context of logic programming, they are expressed as closed formulae. It is desirable to check the integrity of a database at the end of each transaction which changes the database. The simplest approach to checking integrity in a database involves the evaluation of each constraint whenever the database is updated. However, such an approach is too inefficient, especially for large databases, and does not make use of the fact that the database satisfies the constraints prior to the update. A method, called the path finding method, is proposed for checking integrity in definite deductive databases by considering constraints as closed first order formulae. A comparative evaluation is made among previously described methods and the proposed one. Closed general formulae is used to express aggregate constraints and Lloyd et al. 's simplification method is generalised to cope with these constraints. A new definition of constraint satisfiability is introduced in the case of indefinite deductive databases and the path finding method is generalised to check integrity in the presence of static constraints only. To evaluate a constraint in an indefinite deductive database to take full advantage of the query evaluation mechanism underlying the database, a query evaluator is proposed which is based on a definition of semantics, called negation as possible failure, for inferring negative information from an indefinite deductive database. Transitional constraints are expressed using action relations and it is shown that transitional constraints can be handled in definite deductive databases in the same way as static constraints if the underlying database is suitably extended. The concept of irnplicit update is introduced and the path finding method is extended to compute facts which are present in action relations. The extended method is capable of checking integrity in definite deductive databases in the presence of transitional constraints. Combining different generalisations of the path finding method to check integrity in deductive databases in the presence of arbitrary constraints is discussed. An extension of the data manipulation language of SQL is proposed to express a wider range of integrity constraints. This class of constraints can be maintained in a database with the tools provided in this thesis

SOME CHARACTERIZATIONS OF α-COSYMPLECTIC MANIFOLDS ADMITTING ∗-CONFORMAL RICCI SOLITIONS

The object of the present paper is to give some characterizations of α-cosymplectic manifolds admitting ∗-conformal Ricci solitons. Such manifolds with gradient ∗-conformal Ricci solitons have also been considere

Performance Analysis of DSDV, AODV AND AOMDV Routing Protocols Based on Fixed and Mobility Network Model in Wireless Sensor Network

Wireless sensor networks (WSN) is capable of autonomously forming a network without human interaction. Each node in a WSN acts as a router, forwarding data packets to other nodes. Without routing protocols, these routers cannot work together in phase. A central challenge in the design of WSN is the development of routing protocols that can efficiently find routes in a network. The question is which criteria should be considered when selecting a routing protocol, for instance, energy consumption (battery life), bandwidth, or security? We selected energy consumption as this is the most important criterion in WSN. To find out the best routing protocol, we analyzed three routing protocols namely AODV (Ad-hoc On Demand Distance Vector), AOMDV (Ad-hoc On Demand Multiple Distance Vector), and DSDV (Destination Sequence Distance Vector). Overall performance of these protocols was analyzed by comparing end-to-end delay, throughput, normalized routing load, and energy consumption of the network. This was accomplished by using the Network Simulator, NS-2.34 over IEEE 802.11. The analysis shows that AOMDV is the best routing protocol in terms of energy consumption

Cloning and characterization of mutL and mutS genes of Vibrio cholerae: nucleotide sequence of the mutL gene

The mutL and mutS genes of Vibrio cholerae have been identified using interspecific complementation of Escherichia coli mutL and mutS mutants with plasmids containing the gene bank of V. cholerae. The recombinant plasmid pJT470, containing a 4.7 kb fragment of V. cholerae DNA codes for a protein of molecular weight 92,000. The product of this gene reduces the spontaneous mutation frequency of the E. coli mutS mutant. The plasmid, designated pJT250, containing a 2.5 kb DNA fragment of V. cholerae and coding for a protein of molecular weight 62,000, complements the mutL gene function of E. coli mutL mutants. These gene products are involved in the repair of mismatches in DNA. The complete nucleotide sequence of mutL gene of V. cholerae has been determined

In vitro protein folding by ribosomes from Escherichia coli, wheat germ and rat liver

Ribosomes from a number of prokaryotic and eukaryotic sources (e.g., Escherichia coli, wheat germ and rat liver) can refold a number of enzymes which are denatured with guanidine/HCl prior to incubation with ribosomes. In this report, we present our observations on the refolding of denatured lactate dehydro-genase from rabbit muscle and glucose-6-phosphate dehydrogenase from baker's yeast by ribosomes from E. coli, wheat germ and rat liver, The protein-folding activity of E. coli, ribosomes was found to be present in 50s particles and in 23S rRNA. The 30S particle or 16S rRNA did not show any protein-folding activity. The protein-folding activity of 23S rRNA may depend on its tertiary conformation. Loss of tertiary structure, by incubation with low concentrations of EDTA, inhibited the protein-folding activity of 23S rRNA. This low concentration of EDTA had no effect on folding of the denatured enzymes by themselves

TCP Performance Over Mobile IP Wired-cum-Wireless Networks

Reliable transport protocol like TCP has served well the wired Internet where the packet losses are mainly due to congestion but is not ready for Mobile IP wired-cum-wireless environments where the significant packet losses are due to bit errors and handoffs In this paper we have investigated the performance of TCP among the various TCP variants We have observed both TCP senders Newreno Vegas and TCP receivers Base Delayed-Ack Using ns-2 we have evaluated the TCP throughput and packet delay over a single TCP connection The simulation results suggest that a particular combination one TCP sender with one TCP receiver of TCP shows the best result in such Mobile IP network

A quick termination detection protocol by reducing overload for mobile ad hoc networks

An ad hoc network is characterized by the fact that there is no fixed topology due to the mobility of nodes, interference, multipath propagation and path loss. Execution of applications in such kind of networks typically consists of a number of successive phases such as network reprogramming, localization, power monitoring, and parameter updates. Termination detection of a phase is therefore a critical operation to safely execute a new phase on some or all of the network nodes. In resource constrained network environment the overhead should be minimum in order to increase throughput and minimize delay. This paper studies the existing solutions for termination detection by analyzing their effectiveness. Moreover, in this paper, we propose an efficient algorithmic solution to encounter termination detection by minimizing the network overloads

Health Assessment of Large Two Dimensional Structures Using Limited Information: Recent Advances

Some recent advances of a recently developed structural health assessment procedure proposed by the research team at the University of Arizona, commonly known as generalized iterative least-squares extended Kalman filter with unknown input (GILS-EKF-UI) are presented. The procedure is a finite elements-based time-domain system-identification technique. It can assess structural health at the element level using only limited number of noise-contaminated responses. With the help of examples, it is demonstrated that the structure can be excited by multiple loadings simultaneously. The method can identify defects in various stages of degradation in single or multiple members and also relatively less severe defect. The defective element(s) need not be in the substructure, but the defect detection capability increases if the defect spot is close to the substructure. Two alternatives are suggested to locate defect spot more accurately within a defective element. The paper advances several areas of GILS-EKF-UI to assess health of large structural systems

Thermal insulation properties of jute, polypropylene and recycled polyester nonwoven fabrics for automotive textiles

Three different nonwoven fabrics, namely jute, polypropylene and recycled polyester, have been produced using needle-punching method. The nonwoven fabric samples are then characterised by thermal conductivity, thermal resistance, air permeability, areal density and thickness. Objective and subjective evaluation are carried out for the fabric samples. The fibres are blended in various proportions and further converted into cross laid needle punched nonwoven fabrics. The thermal resistance of carded needle punched nonwoven fabrics are determined by using lee’s disc apparatus. Experimental results show that 100 % recycled polyester nonwoven fabrics thermal resistance behaviour is higher than the jute and polypropylene needle punched nonwoven fabrics. This nonwoven fabric can be used in the automotive field as a headlining material for the purpose of thermal insulation