Magnetoresistive random access memory using magnetic tunnel junctions

Magnetoresistive random access memory (MRAM) technology combines a spintronic device with standard silicon-based microelectronics to obtain a combination of attributes not found in any other memory technology. Key attributes of MRAM technology are nonvolatility and unlimited read and write endurance. Magnetic tunnel junction (MTJ) devices have several advantages over other magnetoresistive devices for use in MRAM cells, such as a large signal for the read operation and a resistance that can be tailored to the circuit. Due to these attributes, MTJ MRAM can operate at high speed and is expected to have competitive densities when commercialized. In this paper, we review our recent progress in the development of MTJ-MRAM technology. We describe how the memory operates, including significant aspects of reading, writing, and integration of the magnetic material with CMOS, which enabled our recent demonstration of a 1-Mbit memory chip. Important memory attributes are compared between MRAM and other memory technologies.     

Description of the shuffle design software MARLA

MARLA is the Studsvik software for the automated design and analysis of a fuel shuffle. The software is currently being applied to Boiling Water Reactors, but will eventually be extended to all Light Water Reactor types. MARLA performs all tasks related to planning the fuel shuffle, including the optimisation of the fuel movement schedule, a complete shutdown margin analysis of all intermediate core configurations using the licensing-grade SIMULATE-3 nodal code, and generation of the official Fuel Movement Checklist used by the crane operators during core alterations. Shutdown margin analysis is interactive with the shuffle design and takes place during the planning stage – not after the sequence has been planned. In addition, MARLA provides the means to manage all fuel pools and nuclear components on site, as well as optimise the choice of bundles to be loaded into dry storage casks to open space in the storage pools to meet future storage needs. This paper describes the software in superficial detail.     

Effects of stratification on the performance of liquid-based solar heating systems

A theoretical model is presented which predicts the effects of storage tank stratification on the instantaneous performance of a liquid-based solar heating system. The results are presented in terms of a stratification coefficient which is defined to be the ratio of the actual useful energy gain to the energy gain that would be achieved in a fully mixed tank. This stratification coefficient is shown to be a system constant which depends on only two dimensionless system parameters. The closed form model is compared with a detailed numerical simulation and also with experimental data taken with a solar water heater. Both the simulation data and the experimental data agree favorably with the theoretical model.     

A Highly Fatigue-Resistant Zr-Based Bulk Metallic Glass

The strength-normalized fatigue endurance strength of the bulk metallic glass (BMG) Zr_52.5Cu_17.9Ni_14.6Al₁₀Ti₅ (Vitreloy 105) has been reported to be the highest for any BMG; however, to date, there has been no explanation of why this material is so much better than other Zr-based compositions. In this study, the fatigue-crack growth behavior of Zr_52.5Cu_17.9Ni_14.6Al₁₀Ti₅ was compared in ambient air vs dry nitrogen environment. The excellent fatigue life behavior is attributed to a relatively high fatigue threshold (ΔK _TH ≈ 2 MPa√m) and a lack of sensitivity to environmental effects on fatigue-crack growth in ambient air, as compared to other Zr-based BMGs. Fatigue life experiments conducted in ambient air confirmed the excellent fatigue life properties with a 10⁷-cycle endurance strength of ~0.24 of the ultimate tensile strength; however, it was also found that casting porosity, even in limited amounts, could reduce this endurance strength by as much as ~60 pct. Overall, the BMG Zr_52.5Cu_17.9Ni_14.6Al₁₀Ti₅ appears to have excellent strength and fatigue properties and should be considered as a prime candidate material for future applications where good mechanical fatigue resistance is required.     

How Can I Help You? Call Centres,Classification Work and Coordination

As a comparatively novel but increasingly pervasive organizational arrangement, call centres have been a focus for much recent research. This paper identifies lessons for organizational and technological design through an examination of call centres and ‘classification work’ – explicating what Star [1992, Systems/Practice vol. 5, pp. 395–410] terms the ‘open black box’. Classification is a central means by which organizations standardize procedure, assess productivity, develop services and re-organize their business. Nevertheless, as Bowker and Star [1999, Sorting Things Out: Classification and Its Consequences. Cambridge MA: MIT Press] have pointed out, we know relatively little about the work that goes into making classification schema what they are. We will suggest that a focus on classification ‘work’ in this context is a useful exemplar of the need for some kind of ‘meta-analysis’ in ethnographic work also. If standardization is a major ambition for organizations under late capitalism, then comparison might be seen as a related but as-yet unrealized one for ethnographers. In this paper, we attempt an initial cut at a comparative approach, focusing on classification because it seemed to be the primary issue that emerged when we compared studies. Moreover, if technology is the principal means through which procedure and practice is implemented and if, as we believe, classifications are becoming ever more explicitly embedded within it (for instance with the development of so-called ‘semantic web’ and associated approaches to ontology-based design), then there is clearly a case for identifying some themes which might underpin classification work in a given domain.     

Adding phonetic similarity data to a lexical database

As part of a project to construct an interactive program which would encourage children to play with language by building jokes, we developed a lexical database, starting from WordNet. To the existing information about part of speech, synonymy, hyponymy, etc., we have added phonetic representations and phonetic similarity ratings for pairs of words/phrases.

High‐Resolution Submillimeter Wave Spectroscopy of Hydrogen Sulphide with Heterodyne Spectrometer

A submillimeter heterodyne spectrometer using continuous wave optically pumped molecular laser as local oscillator and Schottky diode as mixer was developed at Physical Research Laboratory, Ahmedabad (India) for quantitative spectroscopy of polyatomic molecules in laboratory. The experimental details of spectrometer and its application to study of molecular line parameters are presented. In particular line strength, collision line width (self and foreign) of H₂S 5_5,0←5_4,1 transition¹(579.799 GHz) have been measured. Air molecules have been used as foreign (perturbing) molecules taking Earth’s atmosphere into consideration².