Reliability analysis of a three-state multi-component warm standby redundant complex system with waiting for repair

Investigations have been carried out with the help of Laplace transforms and supplementary variable techniques for the evaluation of reliability analysis of a three-state multi-component warm standby redundant complex system suffering three types of failures, namely minor, major, and human due to critical human errors incorporating the concept of waiting for repair.     

Hybrid connection algorithm: A strategy for efficient restoration in WDM optical networks

In present communication, we propose a modified resource allocation strategy, namely, hybrid connection algorithm, for achieving efficient restoration in WDM optical networks. The main theme of the algorithm is that, while attempting connection establishment, a wavelength is reserved in advance for providing resources for backup lightpaths. The analysis and the comparison of the proposed strategy with other existing strategies has been undertaken using metrics such as, restoration efficiency, number of wavelength links used by primary and backup lightpaths, and the percent link utilization. The proposed strategy provides 100% restoration efficiency and much better performance than the existing techniques.     

Constructing Multilevel Metadata Networks for Sharing Dispersed and Transient Information in a Mobile Environment

An intelligent multi-user mechanism has been prototyped at the Information System Collaboratory of the Pennsylvania State University, which is capable of resolving global queries with differing and overlapping information needs, spatial scalability and temporal assumptions. The sources of information for this prototype are mechanical damage monitoring sensors embedded in equipment at plant sites, on-board ships or aircrafts, archived historical and diagnostic databases like those available through NALCOMIS (NAVMASSO document J-004 EM-001C, 1995) logistics and maintenance databases at depots, interactive electronic technical manuals stored in databases, dynamic models of damage, and models of operational performance. The concept-of-operation includes mobile access to this information by equipment maintainers on-board ships, aircrafts and other mobile platforms. Real-time interoperation of these system components and databases, under dynamic equipment operating conditions of thermo-mechanical and environmental stress, requires complex interactions of internal representations of sensor data, performance requirements, resources and equipment models, with rich semantics. To support such interactions, following the work of Bright, Hurson and Pakzad (Bright, Hurson, and Pakzad, Transactions on Database Systems, Vol. 19, No. 2, pp. 212–253, 1994) local schema terms of available data sources are organized as the leaf nodes in a semantic network of metadata. The physical nodes of the network are partitioned into a top-down multi-level search control structure of increasing precision and decreasing semantic aggregation. Each physical node supports search through all lower layers of metadata in connected tree configurations. The resulting multilayered semantic network is modeled as a Thesaurus of terms T and relationships R. A relationship in R may be crisp or fuzzy. The DTIC (Defense Technical Information Center) thesaurus for equipment maintenance was used as a starting point in this work. It was further enhanced by application specific terms and endowed with a distance function. This distance function is used to formulate user adaptable Graphic User Interfaces (GUI) for making quality of service tradeoffs in the resolution of global queries.Step-by-step construction of the thesaurus as a multilevel metadata network, its scalability, dynamic adaptation through usage, and tolerance of semantic imprecision in query resolution are discussed in this paper. Furthermore, performance metrology for evaluating quality of service in global query resolution is also developed (Phoha, in Proceedings of the NIST Workshop on Advancing Measurements and Testing for Information Technology, Gaithersburg, MD, Oct. 1998).This work was funded by DARPA for the past four years under grant DE-FC36-94G010064, for establishing a National Information Infrastructure Testbed for Electronic Commerce in equipment health monitoring, failure diagnosis and prognosis services.     

Proteomics analysis of carbon-starved Mycobacterium smegmatis: induction of Dps-like protein

Mycobacterium tuberculosis is a globally successful pathogen,infecting more than one third of total world's population. Thesebacteria have the remarkable ability to persist in the hostfor long periods of time unrecognized by the immune system andthen to re-emerge later in life causing the disease. The physiologyof such persistent or dormant bacilli is not very well characterized.Some evidence suggests that the dormant bacilli survive in anutrient-deprived state that is similar to the stationary phaseof the bacteria with respect to gene expression and physiology.Under this assumption we have studied the survival of Mycobacteriumsmegmatis in carbon starvation conditions as a model for mycobacterialpersistence. M.smegmatis, being a fast-growing strain, servesas a good model to study starvation responses. Using the two-dimensionalelectrophoresis-based proteomics approach, we identified a proteinwhich was found to be expressed preferentially under starvationconditions. This protein is homologous to a family of proteinscalled Dps (DNA binding Protein from Starved cells) that areknown to protect DNA under various kinds of environmental stressesand its existence has, so far, not been reported in mycobacteria.Upon expression and purification of this protein, we observedthat it has non-specific DNA-binding ability. Formation of acage-like dodecamer structure is a characteristic feature ofDps. Using comparative modelling we were able to show that Dpsfrom M.smegmatis could form a dodecamer structure similar tothe crystal structure of Dps from Escherichia coli.     

Evaluation of search algorithms and clustering efficiency measures for machine-part matrix clustering

Clustering a machine-part matrix is the first step in the design of a cellular manufacturing system. It provides a basis for matching the machine groups to the part families that they must produce. The problem of clustering a machine-part matrix can be decomposed into two problems: designing a measure for clustering efficiency (CE) and searching for a permutation of rows and columns of the matrix to maximize this measure. Clustering is done by permuting the rows and columns of the initial machine-part matrix to produce a block diagonal form (BDF). The clustering efficiency of a machine-part matrix measures the desirability of its BDF as a solution to cell design. This paper evaluates six measures of CE and six search methods. Extensive experiments were carried out to find the combination of CE measure and search method that produces the best solution in reasonable CPU time. We used several benchmark machine-part matrices from the literature and several problems obtained from a local manufacturer. We performed a multivariate analysis of variance (MANOVA) to compare the search algorithms and the CE measures.     

Implementing a Manufacturing Information System

The adoption of a computer-driven technology should lead to cost reduction, improved control, and increased profitability. However, it should not be adopted just because it has worked well in other organizations. The corporate staff groups, in their zeal to please management, often lose objectivity and plunge into the new system adoption process to the detriment of the organizational welt-being. This article discusses the advantages of implementing a manufacturing information system to help MIS managers coordinate a strategy for CIM - computer-integrated manufacturing.     

A review of self-assembled monolayers as potential terahertz frequency tunnel diodes

In this review, we describe the principles of the tunnel junction, self-assembled monolayer （SAM） application techniques, experimental testbed fabrication, and characterization of the films and devices. In addition, techniques for directed application, removal, and functionalization of the monolayers are discussed. Bottom-up fabrication techniques have seen increased attention because of their versatility and ease of use. These films see mechanical uses as surface modifiers and micro-scale lubricants. Advances in nanowatt electronics and ultra-low power sensors have opened up an energy harvesting niche for solutions which would have proven ineffective just some years ago. The focus of this study is the two- terminal junction which has potential applications in THz rectification for energy harvesting, medical imaging, and defense sensing. The quantum theory of operation behind these devices is touched on briefly---describing tunneling through the organic monolayers. Commentary on trends in research and potential future work are presented as well.     

Compressive deformation behavior of Al 2024 alloy using 2D and 4D processing maps

The hot deformation behavior of Al 2024 was studied by isothermal hot compression tests in the temperature range of 250–500 °C and strain rate range of 10⁻³ to 10² s⁻¹ in a computer-controlled 50 kN servo-hydraulic universal testing machine (UTM). The results show that the flow stress of Al 2024 alloy increases with strain rate and decreases after a peak value, indicating dynamic recovery and recrystallization. The processing map exhibits two domains of optimum efficiency for hot deformation at different strains, including the low strain rate domain at 500 °C and between 10⁻² and 10⁻¹ s⁻¹ and the high strain rate domain in 250 and 300 °C in the strain rate range of 10¹ to 10² s⁻¹. An attempt has been made in this article to generate a new hybrid 4D process map which illustrates contours of power dissipation and instability in the 3D space of strain rate, temperature, and strain.     

A Two-Step Filtering approach for detecting maize and soybean phenology with time-series MODIS data

The crop developmental stage represents essential information for irrigation scheduling/fertilizer management, understanding seasonal ecosystem carbon dioxide (CO₂) exchange, and evaluating crop productivity. In this study, we devised an approach called the Two-Step Filtering (TSF) for detecting the phenological stages of maize and soybean from time-series Wide Dynamic Range Vegetation Index (WDRVI) data derived from Moderate Resolution Imaging Spectroradiometer (MODIS) 250-m observations. The TSF method consists of a Two-Step Filtering scheme that includes: (i) smoothing the temporal WDRVI data with a wavelet-based filter and (ii) deriving the optimum scaling parameters from shape-model fitting procedure. The date of key crop development stages are then estimated by using the optimum scaling parameters and an initial value of the specific phenological date on the shape model, which are preliminary defined in reference to ground-based crop growth stage observations. The shape model is a crop-specific WDRVI curve with typical seasonal features, which were defined by averaging smoothed, multi-year WDRVI profiles from MODIS 250-m data collected over irrigated maize and soybean study sites.In this study, the TSF method was applied to MODIS-derived WDRVI data over a 6-year period (2003 to 2008) for two irrigated sites and one rainfed site planted to either maize or soybean as part of the Carbon Sequestration Program (CSP) at the University of Nebraska-Lincoln. A comparison of satellite-based retrievals with ground-based crop growth stage observations collected by the CSP over the six growing seasons for these three sites showed that the TSF method can accurately estimate the date of four key phenological stages of maize (V2.5: early vegetative stage, R1: silking stage, R5: dent stage and R6: maturity) and soybean (V1: early vegetative stage, R5: beginning seed, R6: full seed and R7: beginning maturity). The root mean square error (RMSE) of phenological-stage estimation for maize ranged from 2.9 [R1] to 7.0 [R5] days and from 3.2 [R6] to 6.9 [R7] days for soybean, respectively. In addition, the TSF method was also applied for two years (2001 and 2002) over eastern Nebraska to test its ability to characterize the spatio-temporal patterns of these key phenological stages over a larger geographic area. The MODIS-derived crop phenological stage dates agreed well with the statistical crop progress data reported by the United State Department of Agriculture (USDA) National Agricultural Statistics Service (NASS) for eastern Nebraska's three crop agricultural statistic districts (ASDs). At the ASD-level, the RMSE of phenological-stage estimation ranged from 1.6 [R1] to 5.6 [R5] days for maize and from 2.5 [R7] to 5.3 [R5] days for soybean.     

Cine MPR: interactive multiplanar reformatting of four-dimensional cardiac data using hardware-accelerated texture mapping

Four-dimensional (4-D) imaging to capture the three-dimensional (3-D) structure and motion of the heart in real time is an emerging trend. We present here our method of interactive multiplanar reformatting (MPR), i.e., the ability to visualize any chosen anatomical cross section of 4-D cardiac images and to change its orientation smoothly while maintaining the original heart motion. Continuous animation to show the time-varying 3-D geometry of the heart and smooth dynamic manipulation of the reformatted planes, as well as large image size (100-300 MB), make MPR challenging. Our solution exploits the hardware acceleration of 3-D texture mapping capability of high-end commercial PC graphics boards. Customization of volume subdivision and caching concepts to periodic cardiac data allows us to use this hardware effectively and efficiently. We are able to visualize and smoothly interact with real-time 3-D ultrasound cardiac images at the desired frame rate (25 Hz). The developed methods are applicable to MPR of one or more 3-D and 4-D medical images, including 4-D cardiac images collected in a gated fashion.