Enhancing an Application Server to Support Available Components

Three-tier middleware architecture is commonly used for hosting enterprise distributed applications. Typically the application is decomposed into three layers: front-end, middle tier and back-end. Front-end ('Web server') is responsible for handling user interactions and acts as a client of the middle tier, while back-end provides storage facilities for applications. Middle tier ('Application server') is usually the place where all computations are performed. The benefit of this architecture is that it allows flexible management of a cluster of computers for performance and scalability; further, availability measures, such as replication, can be introduced in each tier in an application specific manner. However, incorporation of availability measures in a multi-tier system poses challenging system design problems of integrating open, non proprietary solutions to transparent failover, exactly once execution of client requests, non-blocking transaction processing and an ability to work with clusters. This paper describes how replication for availability can be incorporated within the middle and back-end tiers meeting all these challenges. The paper develops an approach that requires enhancements to the middle tier only for supporting replication of both the middleware backend tiers. The design, implementation and performance evaluation of such a middle are presented.     

A WEB-BASED SYSTEM FOR REVERSE MANUFACTURING AND PRODUCT ENVIRONMENTAL IMPACT ASSESSMENT CONSIDERING END-OF-LIFE DISPOSITIONS

Widespread usage of electronic equipment and shortened product life cycles have challenged original equipment manufacturers (OEMs) to handle End-Of-Life (EOL) product through environmentally benign reverse manufacturing and reusable resources recovery. This paper presents a web-based decision support and evaluation system for operations in remanufacturing and recycling including electronic product disassembly, materials recovery, and recycling management. An overall evaluation of the product's lifecycle environmental impact considering EOL dispositions is also provided. The system has been tested by a major computer manufacturer with computer systems including desktop, laptop, and server. Comprehensive product analysis and environmental impact assessment are discussed in the paper.     

The CORBA Activity Service Framework for supporting extended transactions

Although it has long been realized that ACID (atomicity, consistency, isolation, durability) transactions by themselves are not adequate for structuring long‐lived applications and much research work has been done on developing specific extended transaction models, no middleware support for building extended transactions is currently available and the situation remains that a programmer often has to develop application specific mechanisms. The CORBA Activity Service Framework described in this paper is a way out of this situation. The design of the service is based on the insight that the various extended transaction models can be supported by providing a general purpose event signalling mechanism that can be programmed to enable activities—application specific units of computations—to coordinate each other in a manner prescribed by the model under consideration. The different extended transaction models can be mapped onto specific implementations of this framework, permitting such transactions to span a network of systems connected indirectly by some distribution infrastructure. The framework described in this paper is an overview of the OMG's (Object Management Group) Additional Structuring Mechanisms for the OTS standard. Through a number of examples the paper shows that the framework has the flexibility to support a wide variety of extended transaction models. Although the framework is presented here in CORBA specific terms, the main ideas are sufficiently general, so that it should be possible to use them in conjunction with other middleware. Copyright © 2003 John Wiley & Sons, Ltd.     

Silicon Carbide Ceramic Particulate Reinforced AA2024 Alloy Composite - Part I: Evaluation of Mechanical and Sliding Tribology Performance

In this research work, a master batch (comprising of AA2024 alloy, Silicon Nitride (Si3N4) and Graphite particulates) was reinforced by Silicon-Carbide (SiC) ceramic particulates (0–6 wt.-%; at steps of 2%; i.e. four composites samples viz. ASC-0; ASC-2; ASC-4; ASC-6) with the aim of enhancing mechanical and sliding tribology performance. The semi-automatic stir-casting fabrication process was followed as per standard industrial practice in-order-to fabricate the sample plates of the said alloy composites as per design. Thereafter, the sample specimens were prepared via wire EDM cutting followed by polishing over emery paper; as per ASTM standard dimensions and various physical (density and void content), mechanical (tensile strength, flexural strength, impact strength, hardness etc.), sliding tribology performance (steady state sliding wear; ASTM G-99; Pin-on-Disc tribo-meter), thermal (thermal conductivity, Thermo-Gravimetric Analysis (TGA)); thermo-mechanical (Dynamic Mechanical Analysis (DMA)), fracture-analysis, X-ray diffraction (XRD) etc. characterisation were performed and discussed. In Part-1: Physical, mechanical and sliding tribology performances were discussed. The Taguchi design of experiment technique was employed for designing of experimental runs having input controlling parameters like sliding velocity (0.654–2.616 m/s), sliding distance (784.8–3139.2 m), normal load (5–50 N), reinforcement content (0–6 wt.-%) and environment temperature (20–50 °C). The worn surface morphology studies were performed to understand prevalent wear mechanism using Field Emission Scanning Electron Microscope (FESEM) along with Energy-dispersive X-ray spectroscopy (EDS) that reveals elemental composition and its dispersion on the surface. In Part-2: evaluation of characterizations like thermal, thermo-mechanical, fracture-analysis, X-ray diffraction (XRD) etc. were discussed in correlation with mechanical and sliding wear performance. In Part-3: the entire performance data are analysed using hybrid AHP-TOPSIS technique (an MCDM technique; computationally simple and easy to understand) in-order-to rank the composites formulations.     

Development of electrical conductivity with minimum possible percolation threshold in multi-wall carbon nanotube/polystyrene composites

A method is reported that involves the bulk polymerization of styrene monomer in the presence of multi-wall carbon nanotubes (MWCNTs) and polystyrene (PS) beads, for the preparation of MWCNT/PS conducting composites with a significantly lower (0.08 wt.% MWCNT) percolation threshold than previously reported. Thus, the conductivities of 7.62 × 10⁻⁵ and 1.48 × 10⁻³ S cm⁻¹ were achieved in the MWCNT/PS composites through homogeneous dispersion of 0.08 and 0.26 wt.% CNTs, respectively in the in situ polymerized PS region by using 70 wt.% PS beads during the polymerization. The extent of dispersion and location of the MWCNTs in the PS matrix has been investigated with a scanning and transmission electron microscopy. The conductivity of the composites was increased with increasing wt.% of the PS beads at a constant CNT loading, indicating the formation of a more continuous network structure of the CNTs in PS matrix.     

A family of trusted third party based fair-exchange protocols

Fair exchange protocols play an important role in application areas such as e-commerce where protocol participants require mutual guarantees that a transaction involving exchange of items has taken place in a specific manner. A protocol is fair if no protocol participant can gain any advantage over an honest participant by misbehaving. In addition, such a protocol is fault-tolerant if the protocol can ensure that an honest participant does not suffer any loss of fairness despite any failures of the participant's node. This paper presents a family of fair exchange protocols for two participants which make use of the presence of a trusted third party, under a variety of assumptions concerning participant misbehavior, message, delays, and node reliability. The development is systematic, beginning with the strongest set of the assumptions and gradually weakening the assumptions to the weakest set. The resulting protocol family exposes the impact of a given set of assumptions on solving the problem of fair exchange. Specifically, it highlights the relationships that exist between fairness and assumptions on the nature of participant misbehavior, communication delays, and node crashes. The paper also shows that the restrictions assumed on a dishonest participant's misbehavior can be realized through the use of smartcards and smartcard-based protocols.     

Preparation and characterization of nanostructured ZnO thin films for photoelectrochemical splitting of water

Nanostructured zinc oxide thin films (ZnO) were prepared on conducting glass support (SnO₂: F overlayer) via sol-gel starting from colloidal solution of zinc acetate 2-hydrate in ethanol and 2-methoxy ethanol. Films were obtained by spin coating at 1500 rpm under room conditions (temperature, 28–35°C) and were subsequently sintered in air at three different temperatures (400, 500 and 600°C). The evolution of oxide coatings under thermal treatment was studied by glancing incidence X-ray diffraction and scanning electron microscopy. Average particle size, resistivity and bandgap energy were also determined. Photoelectrochemical properties of thin films and their suitability for splitting of water were investigated. Study suggests that thin films of ZnO, sintered at 600°C are better for photoconversion than the films sintered at 400 or 500°C. Plausible explanations have been provided.     

A distinct strategy to generate high-affinity peptide binders to receptor tyrosine kinases

We describe a novel and general way of generating high affinity peptide (HAP) binders to receptor tyrosine kinases (RTKs), using a multi-step process comprising phage-display selection, identification of peptide pairs suitable for hetero-dimerization (non-competitive and synergistic) and chemical synthesis of heterodimers. Using this strategy, we generated HAPs with K(D)s below 1 nM for VEGF receptor-2 (VEGFR-2) and c-Met. VEGFR-2 HAPs bound significantly better (6- to 500-fold) than either of the individual peptides that were used for heterodimer synthesis. Most significantly, HAPs were much better (150- to 800-fold) competitors than monomers of the natural ligand (VEGF) in various competitive binding and functional assays. In addition, we also found the binding of HAPs to be less sensitive to serum than their component peptides. We believe that this method may be applied to any protein for generating high affinity peptide (HAP) binders.     

Magnetic resonance in high-temperature superconductors

Since the discovery of high-temperature superconductors a new microwave absorption has been found. The microwaves are absorbed in the flux-quantized eigenstates so that the absorption is proportional to the Josephson current and hence it varies as the gap of the superconductor. This absorption is found in the electron-paramagnetic resonance configuration. The flux-quantized fields are found in small domains of the size of 10⁻⁶ cm. A giant moment is found to occur. The necessary theory as well as experiments in YBa₂Cu₃O_7−δ type compounds are described. The Cu²⁺ electron-paramagnetic resonance gives an anisotropic exchange narrowed line with anisotropicg-values withg-shift proportional to susceptibility. The symmetry of theg-value also reflects the symmetry of the superconducting gap.