The OODB path-method generator (PMG) using access weights and precomputed access relevance

A path-method is used as a mechanism in object-oriented databases (OODBs) to retrieve or to update information relevant to one class that is not stored with that class but with some other class. A path-method is a method which traverses from one class through a chain of connections between classes and accesses information at another class. However, it is a difficult task for a casual user or even an application programmer to write path-methods to facilitate queries. This is because it might require comprehensive knowledge of many classes of the conceptual schema that are not directly involved in the query, and therefore may not even be included in a user's (incomplete) view about the contents of the database. We have developed a system, called path-method generator (PMG), which generates path-methods automatically according to a user's database-manipulating requests. The PMG offers the user one of the possible path-methods and the user verifies from his knowledge of the intended purpose of the request whether that path-method is the desired one. If the path method is rejected, then the user can utilize his now increased knowledge about the database to request (with additional parameters given) another offer from the PMG. The PMG is based on access weights attached to the connections between classes and precomputed access relevance between every pair of classes of the OODB. Specific rules for access weight assignment and algorithms for computing access relevance appeared in our previous papers [MGPF92, MGPF93, MGPF96]. In this paper, we present a variety of traversal algorithms based on access weights and precomputed access relevance. Experiments identify some of these algorithms as very successful in generating most desired path-methods. The PMG system utilizes these successful algorithms and is thus an efficient tool for aiding the user with the difficult task of querying and updating a large OODB. Received July 19, 1993 / Accepted May 16, 1997     

Low temperature UV/ozone oxidation formation of HfSiON gate dielectric

Physical and electrical properties of hafnium silicon oxynitride (HfSi_xO_yN_z) dielectric films prepared by UV ozone oxidation of hafnium silicon nitride (HfSiN) followed by annealing to 450 °C are reported. Interfacial layer growth was minimized through room temperature deposition and subsequent ultraviolet/ozone oxidation. The capacitance–voltage (C–V) and current–voltage (I–V) characteristics of the as-deposited and annealed HfSi_xO_yN_z are presented. These 4 nm thick films have a dielectric constant of 8–9 with 12 at.% Hf composition, with a leakage current density of 3×10⁻⁵ A/cm² at V_fb+1 V. The films have a breakdown field strength >10 MV/cm.     

Impact of hydrogen generated by splitting water with nano-silicon and nano-aluminum on diesel engine performance

Efficient utilization of hydrogen generated during the reactions of nano-silicon/water and nano-aluminum/water in internal combustion engine has been investigated in the current work. Engine performance and emission studies of formulated and stabilized nanoemulsion fuels (water in diesel W/D), nano-aluminum in water/diesel (W/DA) and water in nano-silicon/diesel (W/DS) have been compared with those of diesel. Experimental investigations showed reduction in brake specific fuel consumption (BSFC) by 21% and 37%; rise in brake thermal efficiency (BTE) by 16% and 14% when engine was fueled with W/DA and W/DS respectively. For nanoemulsion fuels an increase in induced power was also recorded. Brake mean effective pressure, BTE and NOx emission dropped for W/D due to reduced exhaust gas temperatures. Nevertheless due to elevated peak cylinder pressures and exhaust gas temperatures a marginal rise in NOx, CO, HC and radiative heat emissions was observed with W/DA and W/DS.     

Remote sensing and GIS for locating favourable zones of lead-zinc-copper mineralization in Rajpura-Dariba area,Rajasthan, India

This paper reports the results of a pilot study carried out in RajpuraDariba area, Rajasthan, for locating favourable zones of lead-zinc-copper (Pb-Zn-Cu) mineralization using remote sensing, Geographical Information System (GIS) and geostatistical modelling techniques. Remotely sensed data, both aerial and satellite, were used to update the existing geological map. ATLAS GIS software and multivariate geostatistical techniques were used to analyse and integrate different types of geological and geophysical datasets. The Favourability Index (FI) maps prepared during this study show the occurrence of three favourable zones for Pb-Zn-Cu mineralization. They are: (i) around and north of Rawan ka Khera; (ii) isolated spots between Ruppura and Bhupalsagar; and (iii) north of Dhani. Selective geochemical sampling and resistivity profiling carried out in these favourable zones indicated the presence of geochemical anomalies (anomalous concentrations of Zn and Cu) and low/moderate resistivity zones, respectively. Recent drilling carried out by the Department of Mines and Geology (DMG), Rajasthan, at about 2.5 km north of Rawan ka Khera (one of the predicted favourable zones) indicated evidence of Cu mineralization at a depth of about 70 m.     

A Review on Dissimilar Friction Stir Welding of Copper to Aluminum: Process,Properties, and Variants

Copper and aluminum materials are extensively used in different industries because of its great conductivities and corrosion resistant nature. It is important to join dissimilar materials such as copper and aluminum to permit maximum use of the special properties of both the materials. The joining of dissimilar materials is one of the most advanced topics, which researchers have found from last few years. Friction stir welding (FSW) technology is feasible to join dissimilar materials because of its solid state nature. Present article provides a comprehensive insight on dissimilar copper to aluminum materials joined by FSW technology. FSW parameters such as tool design, tool pin offset, rotational speed, welding speed, tool tilt angle, and position of workpiece material in fixture for dissimilar Cu–Al system are summarized in the present review article. Additionally, welding defects, microstructure, and intermetallic compound generation for Cu–Al FSW system have been also discussed in this article. Furthermore, the new developments and future scope of dissimilar Cu–Al FSW system have been addressed.     

Distributed Dynamic Backhauling in Aerial Heterogeneous Networks

Wireless Personal Communications - A Wireless Mesh Network (WMN) is a multi-hop network that gains the benefits of low deployment cost, fast access speed, expanded service coverage and large...     

The outlook of zeolite-Y hampered metal–ligand framework as heterogeneous catalysts: synthesis,spectral account and catalytic features

Zeolite-Y enslaved complexes were prepared by the Flexible ligand method. Synthesized materials were characterized by various spectral tools like powder X-ray diffraction, spectral studies (UV–Vis and FT-IR), chemical analysis (ICP-OES and elemental), scanning electron microscopy, AAS and ¹H-NMR techniques. Further, BET and thermogravimetric (TG) analysis were also done for characterization of surface area, pore volume, thermal behavior, and related parameters. Baeyer–Villiger oxidation of cyclohexanone was carried out over Zeolite-Y enslaved complexes using hydrogen peroxide (H₂O₂) as an oxidant. The performance of the heterogeneous system with the homogeneous system was compared to determine the protection effect of the zeolitic matrix over the active center on the catalytic properties. In addition, the effect of experimental variables (various solvents, amount of catalyst, the mole ratio of substrate and oxidant, temperature, and reaction time) was examined in order to get absolute reaction conditions. Under the optimized reaction conditions, [Fe(nbab)₂]-Y was found to be a potential candidate, achieving 70 % ?-caprolactone selectivity.     

Mechanical Properties Anisotropy of Cold-Rolled and Solution-Annealed Ni-Based Hastelloy C-276 Alloy

This work describes a correlation among texture, in-plane anisotropy in tensile properties, and yield locus in Ni-based Hastelloy C-276 alloy. The alloy exhibits moderate values of in-plane anisotropy and anisotropy index, which has been attributed to the presence of moderate overall intensity of texture. The alloy displays two slopes in true plastic stress–strain curve and follows a Ludwigson relation. At low plastic strains, the sample displays the presence of annealing twins and less strain localization at grain boundaries, while the formation of deformation twins and high strain localization within the deformation twins and at the grain boundaries are observed in a high-strained region. The 45-deg and 67.5-deg orientation samples show relatively low ductility and low work-hardening exponent. This has been explained based on dislocation storage capacity and dynamic recovery coefficient using Kock–Mecking–Estrin analysis.