888 research outputs found
Programming languages: a brief review
In this article we review the development of programming languages and classify them based on their structures and their applications
Building blocks of e-commerce
This article examines the architecture of e-commerce as a set of layers, each supporting the one above it. The layers have clean interfaces, that is, they can be designed independently. We present an architecture with six layers. The lowest layer consists of a physical communication network such as local area network or public switched telephone networks. The next higher layer is the logical layer which describes the protocol used to interconnect communication systems to create internet, intranet and extranet. The services provided over the internet infrastructure, namely, e-mail, world wide web etc., are described in what is called network services layer. It is essential to ensure security of messages, documents etc., which are transmitted using network services. The messaging layer is thus concerned with encryption methods, both private and public key encryption and their applications. We call the layer above this the middleman service, which is concerned with value-added services offered by intermediaries to enable payment for services received, certify digital signatures, safely transmit documents and provide information on behalf of companies. The topmost layer is the application layer which users see. The major applications are customer-to-business (C2B) e-commerce, business-to-business (B2B) e-commerce, customer-to-consumer (C2C) e-commerce etc. We briefly explain these modes
Of the Analytical Engine: Charles Babbage
This article does not have an abstract
A Data-Flow Language for Specifying Business Data Processing Applications
A high level specification language called Business Data-Flow Language (BDFL) based on the data-flow model of computation is described in this paper. A translator to convert BDFL Specifications into COBOL programs has been implemented. A novel feature of the proposed translation system is the use of Data Base Menagement Systems
(DBMS) in conjunction with COBOL. This relieves the user of the need to design data structures for the intended Data Processing application
Kink-antikink, trapping bags and five-dimensional Gauss-Bonnet gravity
Five-dimensional Gauss-Bonnet gravity, with one warped extra-dimension,
allows classes of solutions where two scalar fields combine either in a
kink-antikink system or in a trapping bag configuration. While the
kink-antikink system can be interpreted as a pair of gravitating domain walls
with opposite topological charges, the trapping bag solution consists of a
domain wall supplemented by a non-topological defect. In both classes of
solutions, for large absolute values of the bulk coordinate (i.e. far from the
core of the defects), the geometry is given by five-dimensional anti-de Sitter
space.Comment: 8 pages, 2 figure
Zero-brane approach to quantization of biscalar field theory about topological kink-bell solution
We study the properties of the topologically nontrivial doublet solution
arisen in the biscalar theory with a fourth-power potential introducing an
example of the spontaneous breaking of symmetry. We rule out the zero-brane
(non-minimal point particle) action for this doublet as a particle with
curvature. When quantizing it as the theory with higher derivatives, we
calculate the quantum corrections to the mass of the doublet which could not be
obtained by means of the perturbation theory.Comment: some references were adde
A survey of checkpointing algorithms for parallel and distributed computers
Checkpoint is defined as a designated place in a program at which normal processing is interrupted specifically to preserve the status information necessary to allow resumption of processing at a later time. Checkpointing is the process of saving the status information. This paper surveys the algorithms which have been reported in the literature for checkpointing parallel/distributed systems. It has been observed that most of the algorithms published for checkpointing in message passing systems are based on the seminal article by Chandy and Lamport. A large number of articles have been published in this area by relaxing the assumptions made in this paper and by extending it to minimise the overheads of coordination and context saving. Checkpointing for shared memory systems primarily extend cache coherence protocols to maintain a consistent memory. All of them assume that the main memory is safe for storing the context. Recently algorithms have been published for distributed shared memory systems, which extend the cache coherence protocols used in shared memory systems. They however also include methods for storing the status of distributed memory in stable storage. Most of the algorithms assume that there is no knowledge about the programs being executed. It is however felt that in development of parallel programs the user has to do a fair amount of work in distributing tasks and this information can be effectively used to simplify checkpointing and rollback recovery
John Backus- inventor of FORTRAN
This article does not have an abstract
Phantom fields: bounce solutions in the early Universe and S-branes
The cosmological model with two phantom scalar fields with the special choice
of field's potential is considered. The obtained regular solution describes a
bounce with a subsequent transition to the de Sitter stage of the expansion of
the Universe. This solution also could be interpreted as a S-brane solution.Comment: one reference and new interpretation of the solution are added, and
the title is change
Gravitating multidefects from higher dimensions
Warped configurations admitting pairs of gravitating defects are analyzed.
After devising a general method for the construction of multidefects, specific
examples are presented in the case of higher-dimensional Einstein-Hilbert
gravity. The obtained profiles describe diverse physical situations such as
(topological) kink-antikink systems, pairs of non-topological solitons and
bound configurations of a kink and of a non-topological soliton. In all the
mentioned cases the geometry is always well behaved (all relevant curvature
invariants are regular) and tends to five-dimensional anti-de Sitter space-time
for large asymptotic values of the bulk coordinate. Particular classes of
solutions can be generalized to the framework where the gravity part of the
action includes, as a correction, the Euler-Gauss-Bonnet combination. After
scrutinizing the structure of the zero modes, the obtained results are compared
with conventional gravitating configurations containing a single topological
defect.Comment: 27 pages, 5 included figure
- …