Significance of Aluminum on Hardness of Titanium Aluminum Nitride Deposited by Magnetron Co-Sputtering

Ti_{1− x} Al _x N films were synthesized by reactive magnetron co-sputtering with different aluminum compositions. X-ray diffraction, secondary ion mass spectrometry, nanoindentation, and atomic force microscopy (AFM) techniques were used to analyze these films. The as-deposited films were crystalline for concentrations of Al (35%, 40%, 55%, and 64%) and at 81% it became amorphous. Nanoindentation hardness increases with aluminum and started to decrease beyond 81% of aluminum. Continuous multicycle indentation technique is used to analyze the failure mode of the film with highest hardness. AFM topography analysis of this film exhibited edge cracks outside and inside the indentation area and sink-in when the penetration reaches the substrate.     

Modeling system behavior for risk and reliability analysis using KBARM

With advances in technology and the growing complexity of technological systems, the job of the reliability/system analyst has become more challenging as they have to study, characterize, measure and analyze the behavior of systems with the help of various traditional analytical (mathematical and statistical) techniques, which require knowledge of the precise numerical probabilities and component functional dependencies, information which is difficult to obtain. Even if data are available they are often inaccurate and are thus subject to uncertainty, i.e. historical records can only represent the past behavior and may be unable to predict the future behavior of the equipment. To cope with such situations, the knowledge‐based approximate reasoning methodologies (KBARMs) provide necessary help. Among them, the fuzzy and grey methodologies are the most viable and effective tools for coping with imprecise, uncertain and subjective information in a consistent and logical manner. In this paper, the authors present a methodological and structured approach (which makes use of both qualitative and quantitative techniques) to model, analyze and predict the failurebehavior of two units, namely the forming and press units of a paper machine, using KBARMs. Various system parameters such as repair time, failure rate, mean time between failures, availability and expected number of failures are computed to quantify the system behavior in terms of fuzzy, crisp and defuzzified values. Furthermore, a risk ranking approach based on fuzzy and grey relational analysis is discussed to prioritize various failure causes associated with the components in failure mode and effects analysis (FMEA). Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis of bulk metallic glass composites using high oxygen containing Zr sponge

The effect of large concentration of oxygen on the microstructural development of Zr–Cu–Al–Ni bulk metallic glass (BMG) alloys, prepared from commercially available Zr sponge, has been studied. Apart from promoting crystallization, increased concentration of oxygen (∼8000 ppm) spawns additional phases. In particular, we report the appearance of α-Zr, dendritic Zr₂Cu phase and the Zr₂Ni type cubic phases. Addition of oxygen scavenger like Yttrium only partially solves the problem. Phase evolution was also found to be sensitive to the cooling rate and hence to the thickness of the cast sample. Thus it is possible to produce a gradient microstructure with predominantly amorphous phase at the outer layer.     

Finite element analysis of sheet Hydromechanical forming of circular cup

Sheet hydroforming is a process of converting flat sheet into desired component geometry by using water pressure in a controlled manner. This paper dealt with sheet Hydromechanical forming (SHMF) of circular cup. In this process, blank is first placed on the lower die (a fluid chamber combined with draw ring) and then after sealing the blank between blank holder and draw ring, punch progresses to deform the blank. Pressure of the fluid chamber is also increased simultaneously with the punch progression. The present work endeavours to understand the effect of strain hardening exponent, anisotropy ratio and interfacial friction between blank and tools surfaces for different modes of deformation––stretching to drawing mode on sheet Hydromechanical forming of circular cups.A finite element (FE) model was developed for simulating the SHMF process using dynamic explicit, commercial code, LsDyna. The model after experimental validation used for studying the effect of above parameters on the process. The analysis reveals that higher cup depth with minimum thinning for forming dominated by stretching mode can be achieved with material of higher anisotropy ratio, strain hardening exponent by using a rough punch and effective lubrication at blank-die–blank holder interfaces. On the other hand in case of drawing as mode of deformation, thinning is influenced mainly by interfacial friction condition between blank and tool surfaces as compared to material properties.     

Initial Shear Modulus of Remolded Sand-Clay Mixtures

This paper presents the dynamic properties of undisturbed and remolded clays and sand-clay mixtures based on the results of undrained hollow cylindrical torsional cyclic simple shear tests. The clays were obtained from different sites having a wide range of plasticity, covering fluvial and marine sediments. The main focus of this investigation is the dynamic properties of sand-clay mixtures whose properties are intermediate between those of clays and sands. The initial shear moduli are examined in terms of fines content, and conventional plasticity index. An equivalent plasticity index has been defined in the present investigation and a better correlation is obtained between the initial shear modulus of sand-clay mixtures and this parameter than with the conventional plasticity index. Further, a simple method has been suggested to determine the equivalent plasticity index based on the conventional consistency limit tests and grain size analysis. An empirical correlation for predicting the initial shear modulus is also proposed.     

Integrated advanced natural wastewater treatment system for small communities.

A study was conducted to evaluate the nutrient removal capability of an existing and successfully operated overland flow and wetland wastewater treatment system following a waste stabilization pond. Seasonal temperature effects on performance were also investigated. The treatment system studied consists of a two-cell waste stabilization pond followed by an overland flow system and a wetland system. The influent and effluent samples were analyzed for BOD5, suspended solids (SS), pH, temperature, ammonia nitrogen, nitrate nitrogen, and total phosphorus. The results of the study indicate that the combined pond, overland flow and wetland system provided excellent treatment of municipal wastewater. The overall average BOD5 removal by the entire treatment system was about 90.0% and the overall average suspended solids removal was about 93.4%. The ammonia nitrogen and total phosphorus removal efficiencies of the entire treatment system were 90.7% and 84.2%, respectively.     

Development of Titanium Coatings on Particulate Diamond

The performance of many wear-resistant materials can be improved further by incorporating diamond into the structure. Diamond that has been coated with titanium is known to adhere well to the matrix particles and also prevents reaction with H₂, which often is used in the sintering atmosphere. Two coating methods of coating diamond with titanium have been explored in this study: a sputtering method and a procedure that involves heating the diamond in a mixture of salt and titanium. The latter, which uses a salt mix of NaCl, KCl, and CaCl₂ and metallic titanium particles 3 μm in size, heated at a temperature of 750°C in an argon atmosphere, is determined to be the best method.     

Can India raise agricultural productivity while reducing groundwater and energy use?

This paper provides empirical evidence that power tariff reform with pro rata pricing and higher unit rates for electricity not only would promote equity, efficiency and sustainability in groundwater use, but also would be socio-economically viable for small-holder farmers. It shows that the arguments of “high transaction cost” and “political infeasibility” used against metering are valid only in specific regional contexts and under increasingly outmoded power-pricing and agricultural-production regimes, if one considers the recent advancements in remote sensing and the facts that overexploited regions have a low density of wells and are mostly owned by farmers who constitute a small segment of the farming community.     

A New Distance Notion for PPAM Space--Time Trellis Codes for UWB MIMO Communications

We introduce a new distance notion and develop novel design criteria for optimal MN-ary pulse position amplitude modulation (PPAM) space-time trellis codes (STTC) for ultrawideband multiple-input multiple-output systems for slow and fast fading at both low and high SNR. Simulation results of the 2,2-ary PPAM STTC, constructed through set partitioning, confirm significant reduction in bit error rate.