Acoustic emission study of phase relations in low-Y2O3 portion of ZrO2-Y2O3 system

The (metastable) tetragonal phase in 3–4 mol% Y₂O₃-ZrO₂ alloys undergoes a transition to the monoclinic form in the 200–300 °C temperature range. Microcracking due to the volume change at this transition has been detected in these compositions by sharp acoustic emission during heating. The phase change was confirmed by X-ray diffraction, dilatometry and scanning electron microscopy. The monoclinic tetragonal transition in ZrO₂-1 mol% Y₂O₃ alloy at 850–750 °C and the same phase change in 2, 3, 4 and 6 mol% Y₂O₃ compositions at the eutectoid temperature of about 560 °C was also clearly signalled by the acoustic emission counts during heating and cooling. There was no significant acoustic emission activity on heating and cooling the 9 and 12 mol% Y₂O₃ compositions, which are cubic. The acoustic emission data thus confirm the phase relations in the 1–12 mol% Y₂O₃ region, established by conventional methods such as differential thermal analysis, dilatometry and X-ray diffraction.     

Design and Analysis of Co-operative Acoustic and Optical Hybrid Communication for Underwater Communication

Underwater communication is an emerging field of research currently, which is an important aspect in predicting the climatic conditions accurately. Underwater communication is disadvantageous when compared with aerial communication because water is basically non transparent and blurred to electromagnetic radiations excluding visible region. In the visible region, factors such as suspended sediments and the presence of aquatic life affects the penetration of light. It may penetrate only upto a few hundreds of metres in clear water and in turbid waters, penetration is even less. Underwater communication is also affected by Intersymbol Interference (ISI) due to multipath fading. Currently, a booming and mature technology called acoustic technology is employed for underwater communication systems. Acoustic systems are proficient for long distance communication. But acoustic communication has limitations. They have very low data rates for monitoring applications and due to velocity of sound in water, it has a huge latency which means a significant time delay. To cope up with the limitations of acoustic communication, we use optical communication whose wavelength lies in the visible region. Optical communication is known for high data rate and low latency. Many accidents take place under water such as the plane crash, ship sinking. It is a tedious job to find the lost debris. Hence an underwater optical link is developed which could identify the lost debris. In this project, a hybrid model comprising of acoustic as well as the optical link is proposed. The comparison between acoustic and optical technique is studied and simulated using MATLAB simulation and the responses were plotted. The simulated results can be used in various applications including climate monitoring, military services.

     

Building a push-button RESOLVE verifier: Progress and challenges

A central objective of the verifying compiler grand challenge is to develop a push-button verifier that generates proofs of correctness in a syntax-driven fashion similar to the way an ordinary compiler generates machine code. The software developer??s role is then to provide suitable specifications and annotated code, but otherwise to have no direct involvement in the verification step. However, the general mathematical developments and results upon which software correctness is based may be established through a separate formal proof process in which proofs might be mechanically checked, but not necessarily automatically generated. While many ideas that could conceivably form the basis for software verification have been known ??in principle?? for decades, and several tools to support an aspect of verification have been devised, practical fully automated verification of full software behavior remains a grand challenge. This paper explains how RESOLVE takes a step towards addressing this challenge by integrating foundational and practical elements of software engineering, programming languages, and mathematical logic into a coherent framework. Current versions of the RESOLVE verifier generate verification conditions (VCs) for the correctness of component-based software in a modular fashion??one component at a time. The VCs are currently verified using automated capabilities of the Isabelle proof assistant, the SMT solver Z3, a minimalist rewrite prover, and some specialized decision procedures. Initial experiments with the tools and further analytic considerations show both the progress that has been made and the challenges that remain.     

A robust and efficient automated docking algorithm for molecular recognition

A completely automated method is described for determining themost likely mode of binding of two (macro)moJecules from theknowledge of their three-dimensional structures alone. The methodis based on well-known graph theoretical techniques and hasbeen used successfully to determine and rationalize the bindingof a number of known macromolecular complexes. In this articlewe present results for a special case of the general molecularrecognition problem—given the information concerning theparticular atoms involved in the binding for one of the molecules,the algorithm can correctly identify the corresponding (contacting)atoms of the other molecule. The approach used can be easilyextended to the general molecular recognition problem and requiresthe extraction of maximal common subgraphs. In these studiesthe docking of the macromolecules was achieved without the aidof computer graphics or other visual aids. The algorithm hasbeen used to determine the correct mode of binding of a proteinantigen to an antibody in 100 min on a DEC micro VAX 3600     

Query processing over incomplete autonomous databases: query rewriting using learned data dependencies

Incompleteness due to missing attribute values (aka “null values”) is very common in autonomous web databases, on which user accesses are usually supported through mediators. Traditional query processing techniques that focus on the strict soundness of answer tuples often ignore tuples with critical missing attributes, even if they wind up being relevant to a user query. Ideally we would like the mediator to retrieve such possibleanswers and gauge their relevance by accessing their likelihood of being pertinent answers to the query. The autonomous nature of web databases poses several challenges in realizing this objective. Such challenges include the restricted access privileges imposed on the data, the limited support for query patterns, and the bounded pool of database and network resources in the web environment. We introduce a novel query rewriting and optimization framework QPIAD that tackles these challenges. Our technique involves reformulating the user query based on mined correlations among the database attributes. The reformulated queries are aimed at retrieving the relevant possibleanswers in addition to the certain answers. QPIAD is able to gauge the relevance of such queries allowing tradeoffs in reducing the costs of database query processing and answer transmission. To support this framework, we develop methods for mining attribute correlations (in terms of Approximate Functional Dependencies), value distributions (in the form of Naïve Bayes Classifiers), and selectivity estimates. We present empirical studies to demonstrate that our approach is able to effectively retrieve relevant possibleanswers with high precision, high recall, and manageable cost.     

Changes in agricultural cropland areas between a water-surplus year and a water-deficit year impacting food security,determined using MODIS 250 m time-series data and spectral matching techniques,in the Krishna River basin (India)

The objective of this study was to investigate the changes in cropland areas as a result of water availability using Moderate Resolution Imaging Spectroradiometer (MODIS) 250 m time-series data and spectral matching techniques (SMTs). The study was conducted in the Krishna River basin in India, a very large river basin with an area of 265 752 km² (26 575 200 ha), comparing a water-surplus year (2000–2001) and a water-deficit year (2002–2003). The MODIS 250 m time-series data and SMTs were found ideal for agricultural cropland change detection over large areas and provided fuzzy classification accuracies of 61–100% for various land‐use classes and 61–81% for the rain-fed and irrigated classes. The most mixing change occurred between rain-fed cropland areas and informally irrigated (e.g. groundwater and small reservoir) areas. Hence separation of these two classes was the most difficult. The MODIS 250 m-derived irrigated cropland areas for the districts were highly correlated with the Indian Bureau of Statistics data, with R ²-values between 0.82 and 0.86.

The change in the net area irrigated was modest, with an irrigated area of 8 669 881 ha during the water-surplus year, as compared with 7 718 900 ha during the water-deficit year. However, this is quite misleading as most of the major changes occurred in cropping intensity, such as changing from higher intensity to lower intensity (e.g. from double crop to single crop). The changes in cropping intensity of the agricultural cropland areas that took place in the water-deficit year (2002–2003) when compared with the water-surplus year (2000–2001) in the Krishna basin were: (a) 1 078 564 ha changed from double crop to single crop, (b) 1 461 177 ha changed from continuous crop to single crop, (c) 704 172 ha changed from irrigated single crop to fallow and (d) 1 314 522 ha changed from minor irrigation (e.g. tanks, small reservoirs) to rain-fed. These are highly significant changes that will have strong impact on food security. Such changes may be expected all over the world in a changing climate.     

Swelling behavior of semi‐interpenetrating polymer network hydrogels composed of poly(vinyl alcohol) and poly(acrylamide‐co‐sodium methacrylate)

Interpenetrating polymer network (IPN) hydrogels based on poly(vinyl alcohol) (PVA) and poly(acrylamide‐co‐sodium methacrylate) poly(AAm‐co‐SMA) were prepared by the semi IPN method. These IPN hydrogels were prepared by polymerizing aqueous solution of acrylamide and sodium methacrylate, using ammonium persulphate/N,N,N¹,N¹‐tetramethylethylenediamine (APS/TMEDA) initiating system and N,N¹‐methylene‐bisacrylamide (MBA) as a crosslinker in the presence of a host polymer, poly(vinyl alcohol). The influence of reaction conditions, such as the concentration of PVA, sodium methacrylate, crosslinker, initiator, and reaction temperature, on the swelling behavior of these IPNs was investigated in detail. The results showed that the IPN hydrogels exhibited different swelling behavior as the reaction conditions varied. To verify the structural difference in the IPN hydrogels, scanning electron microscopy (SEM) was used to identify the morphological changes in the IPN as the concentration of crosslinker varied. In addition to MBA, two other crosslinkers were also employed in the preparation of IPNs to illustrate the difference in their swelling phenomena. The swelling kinetics, equilibrium water content, and water transport mechanism of all the IPN hydrogels were investigated. IPN hydrogels being ionic in nature, the swelling behavior was significantly affected by environmental conditions, such as temperature, ionic strength, and pH of the swelling medium. Further, their swelling behavior was also examined in different physiological bio‐fluids. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 302–314, 2005     

Comparative Studies on the Epoxidation Techniques of Vegetable Oils

Concentrated hydrogen peroxide as well as stronger peracetic acid were prepared by simple methods. Commercial hydrogen peroxide (ca. 30%) was concentrated upto 60% by removing water slowly at low temperature and low pressure. Starting from 60% hydrogen peroxide, strong peracetic acid of 17.2% strength was obtained by a simple operation. Batch epoxidations of vegetable oils such as castor, safflower and linseed oils were carried out for different reaction periods from 2 to 10 hrs and the formation of oxirane oxygen was determined in order to study the effect of epoxidation time, catalyst employed and concentration of hydrogen peroxide as well as of preformed peracetic acid on the extent of epoxidation. The optimum conversions were obtained with 4 hrs reaction period at 50° C by the in situ epoxidation technique using 60% hydrogen peroxide and acid-form of Amberlite-120 resin (chemical grade) as catalyst; the mole ratio of the reactants was unsaturation : hydrogen peroxide : acetic acid (1 : 1.5 : 0.5).     

Effect of phase modifiers TBP and iso-decanol on the extraction and complexation of Eu3+ with CMPO

The effect of tri-n-butyl phosphate (TBP) and iso-decanol as phase modifiers on the complexation of Eu³⁺ with octyl-phenyl N,N-diisobutyl carbamoyl methyl phosphine oxide (CMPO) was studied. On an increase of iso-decanol the extraction efficiency of Eu³⁺ decreases. The metal–ligand stoichiometry was found to be 1:3. The Eu complex of CMPO–TBP was more symmetric compared to CMPO–iso-decanol. The Eu³⁺ complex exhibited D_3h and C_3h symmetry for 30% and 5% iso-decanol, while that for TBP was C_6v. The radiative, non-radiative life time, electric and magnetic dipole transition probabilities, branching ratio, quantum efficiency etc. were evaluated. The covalency between Eu³⁺ and CMPO is as follows: CMPO–TBP < CMPO-5% iso-decanol < CMPO-30% iso-decanol.     

Rate-Type Model for Bituminous Mixtures and Its Application to Sand Asphalt

A variety of hot mix asphalt mixtures are used in highway and runway pavement construction. Each mixture caters to specific needs. Mixtures differ from one another in the type and percentage of aggregates and asphalt used, and their response can be markedly different, and thus there is a need to develop constitutive models that can differentiate between the different kinds of mixtures. In this paper, we outline a general procedure for the constitutive modeling of bituminous mixtures. We illustrate the efficacy of this approach by means of an application to sand asphalt. The governing equations for this special problem reduce to a stiff nonlinear ordinary differential equation and this is solved numerically using Gear’s method. We compare the results of the predictions of the model that we have developed with the compressive creep experiments carried out by Wood and Goetz on a typical sand asphalt mixture and find them to be in good agreement.