The impulse design of transformer oil-cellulose structures

Transformer oil/cellulose structures are often designed based on a cumulative stress criterion derived from experimental tests at power frequency. However, such structures must also meet stringent impulse requirements defined by a basic insulation level (BIL). The industry has tried to establish an equivalence factor to permit power frequency cumulative stress methods to be used to estimate impulse withstand strength. Since the mechanisms of failure differ substantially under surge conditions, there would seem no good reason to suppose that a universal equivalence factor is appropriate. Tests are reported using a 2.3 MV generator to document impulse failure of a number of bulk, creep and hybrid structures to establish the nature of this relationship through statistical comparisons with the established 50/60 Hz methods. Factors varied from 1.94 to 3.34, depending on the configuration. The methodology is described and the results discussed in the context of the design of oil-cellulose structures, having regard to complicating factors such as waveshape and electrode covering. The study permits some speculation about impulse design under hybrid situations (i.e. failure paths involving both creep and bulk liquid).     

A comparative study of exchange and aggregation models in the B2B e-marketplace

This research seeks to provide an economic framework for understanding two major forms of e-marketplaces: aggregation-oriented vs. exchange-oriented e-marketplaces. By analyzing the marginal benefit per transaction in alternative models, we are able to determine the most suitable B2B e-marketplace for a wide variety of product categories, market conditions, and procurement methods. For example, when companies sell commodities in a fragmented market, the aggregation model is suitable for spot purchasing, and the exchange model works best for systematic purchasing. In addition, the effect of supplier consolidation and information technology-enabled cost reduction on model selection is discussed.     

Two-handed volumetric document corpus management

To find a document in the sea of information, you must embark on a search process, usually computer-aided. In the traditional information retrieval model, the final goal is to identify and collect a small number of documents to read in detail. In this case, a single query yielding a scalar indication of relevance usually suffices. In contrast, document corpus management seeks to understand what is happening in the collection of documents as a whole (i.e. to find relationships among documents). You may indeed read or skim individual documents, but only to better understand the rest of the document set. Document corpus management seeks to identify trends, discover common links and find clusters of similar documents. The results of many single queries must be combined in various ways so that you can discover trends. We describe a new system called the Stereoscopic Field Analyzer (SFA) that aids in document corpus management by employing 3D volumetric visualization techniques in a minimally immersive real-time interaction style. This interactive information visualization system combines two-handed interaction and stereoscopic viewing with glyph-based rendering of the corpora contents. SFA has a dynamic hypertext environment for text corpora, called Telltale, that provides text indexing, management and retrieval based on n-grams (n character sequences of text). Telltale is a document management and information retrieval engine which provides document similarity measures (n-gram-based m-dimensional vector inner products) visualized by SFA for analyzing patterns and trends within the corpus     

"Prospective relations between bulimic pathology, depression, and substance abuse: Unpacking comorbidity in adolescent girls": Correction to Stice et al. (2004).

Reports an error in "Prospective Relations Between Bulimic Pathology, Depression, and Substance Abuse: Unpacking Comorbidity in Adolescent Girls" by Eric Stice, Emily M. Burton and Heather Shaw (Journal of Consulting and Clinical Psychology, 2004[Feb], Vol 72[1], 62-71). The findings of Leon, Fulkerson, Perry, Keel, and Klump ("Three to four year prospective evaluation of personality and behavioral risk factors for later disordered eating in adolescent girls and boys," Journal of Youth and Adolescence, 1999, Vol. 28, No. 2, pp. 181-196), cited on page 62, were incorrectly reported. Leon et al. (1999) found that the latent variable of negative affect/attitudes determined at study entrance significantly correlated with final year eating disorder risk score when conducted with the full sample and when removing Time 1 high eating disorder risk subjects. This latent variable consisted of the GBI Depression, MPQ Negative Emotionality, EDI Ineffectiveness, EDI Interoceptive Awareness, and EDI Body Dissatisfaction scales. A subsequent univariate analysis of Time 1 Negative Emotionality scale score on Time 3 eating disorder risk, adjusting for initial eating disorder risk score, showed a nonsignificant effect size (Stice, E. [2002]. Risk and maintenance factors for eating pathology: A meta-analytic review. Psychological Bulletin, 128, 825-848). (The following abstract of the original article appeared in record 2004-10364-006.) To elucidate the processes that contribute to the comorbidity between bulimic pathology, depression, and substance abuse, the authors tested the temporal relations between these disturbances with prospective data from adolescent girls (N = 496). Multivariate analyses indicated that depressive symptoms predicted onset of bulimic pathology but not of substance abuse, bulimic symptoms predicted onset of depression but not of substance abuse, and substance abuse symptoms predicted onset of depression but not of bulimic pathology. Results suggest that the comorbidity arises because certain disorders are risk factors for the other disorders. Findings also provide support for select etiologic theories and further establish the clinical significance of these conditions by showing that they increase risk for onset of other psychiatric disturbances. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Effects of Process Characteristics on the Value of B2B E-Procurement

Even as more organizations are moving towards implementing Web-based B2B procurement solutions, they are unsure of the real benefits of the Web. In other words, what is the value of B2B e-procurement to an organization and how to measure this value? What factors affect this value? In this paper, we discuss an evaluation framework to determine the value of B2B e-procurement and the effect of process characteristics on the value. We use an empirical study to highlight the different value created by different procurement types. We then develop a more comprehensive economic model to capture the additional effects of demand volume and process complexity. The integration of theoretical and empirical approaches provides a strong foundation to develop and evaluate useful adoption strategies for B2B e-procurement.     

Phototoxicity and fluorotoxicity combine to alter the behavior of neutrophils in fluorescence microscopy based flow adhesion assays

The use of fluorescent probes that allow visualization of leukocyte-endothelial cell (EC) interactions has greatly informed our understanding of leukocyte recruitment. However, effects of these agents on the biological functions of leukocytes are poorly described, leading to concerns about the interpretation of such data. Here we used two flow-based neutrophil adhesion assays to compare the effects of phase contrast illumination (PCI) with high intensity illumination (HII) used for fluorescent microscopy, in the presence or absence of five commonly used fluorochromes. Isolated neutrophils were either (1) perfused across P-selectin to establish a population of rolling cells, which were subsequently activated with fMLP; or (2) perfused across EC activated with TNF-alpha. In the absence of fluorescent dyes, HII did not affect levels of leukocyte adhesion; however, subsequent neutrophil behavior was dramatically altered when compared with cells under PCI, for example, dramatically reducing their migration velocities. In the presence of fluorescent dyes, the effects of HII were exacerbated, although the precise nature of the biological effects of these probes was agent specific. Thus, for the first time, our experiments describe the effects of fluorescent microscopy on the separate stages of the neutrophil recruitment process and reveal a previously unsuspected effect of HII on neutrophil migration.     

Computational models of a nano probe tip for static behaviors

It is difficult to predict the measurement bias arising from the compliance of the atomic force microscope (AFM) probe. The issue becomes particularly important in this situation where nanometer uncertainties are sought for measurements with dimensional probes composed of flexible carbon nanotubes mounted on AFM cantilevers. We have developed a finite element model for simulating the mechanical behavior of AFM cantilevers with carbon nanotubes attached. Spring constants of both the nanotube and cantilever in two directions are calculated using the finite element method with known Young's moduli of both silicon and multiwall nanotube as input data. Compliance of the nanotube-attached AFM probe tip may be calculated from the set of spring constants. This paper presents static models that together provide a basis to estimate uncertainties in linewidth measurement using nanotubes. In particular, the interaction between a multiwall nanotube tip and a silicon sample is modeled using the Lennard-Jones theory. Snap-in and snap-out of the probe tip in a scanning mode are calculated by integrating the compliance of the probe and the sample-tip interacting force model. Cantilever and probe tip deflections and points of contact are derived for both horizontal scanning of a plateau and vertically scanning of a wall. The finite element method and the Lennard-Jones model provide a means to analyze the interaction of the probe and sample and measurement uncertainty, including actual deflection and the gap between the probe tip and the measured sample surface.     

A preliminary design and structural analysis of the lifting tools for 40° sector sub-assembly and handling ITER components

The purpose-built, ITER tokamak assembly tools, which are to be provided by Korea, should be designed to meet: the assembly plan, space reservations, safety standards, simple operations, efficient maintenance, and so on. It is very important that the ITER assembly tools are able to lift and transfer ITER components or their sub-assemblies to their assembled position safely. Furthermore, the lifting tools will lift and handle very heavy loads that can be more than 1200 tonnes sometimes. Therefore, the ITER lifting tools must be designed to endure these heavy load conditions with regard to their structural integrity. Also, these designs should be verified through an appropriate method. The preliminary design of the sector lifting tool and associated lifting attachments are introduced in this paper. The sector lifting tool was designed especially to lift and handle various ITER components by adjusting the lifting centre. The structural analysis results using ANSYS are described considering the heaviest load condition. The results of the analysis show that; all stresses applied on the lifting tool are lower than the allowable stress of the applied material.     

Max Penson in Uzbekistan

Photography reached the Ottoman Empire soon after its invention, at about the time that painting began to be practised there as part of a broader project of assimilating aspects of European culture. This was in marked contrast to the situation in Europe, where photography had to contend with visual traditions from which it adopted pictorial conventions and subject matter. Instead of supplanting existing traditions of realistic visual representation, photography in the Ottoman Empire served as a discrete source of inspiration. This paper examines how this inversion of European experience within the Ottoman Empire provides an alternative to dominant narratives of photographic history. If one of the salient characteristics of modernist movements in Western art is their ability to break with tradition, then the adoption of Western practices of representation by artists within the Ottoman Empire may be viewed as a radical modernist success.     

Impact of air‐handling system exhaust failure on dissemination pattern of simulant pathogen particles in a clinical biocontainment unit

Biocontainment units (BCUs) are facilities used to care for patients with highly infectious diseases. However, there is limited guidance on BCU protocols and design. This study presents the first investigation of how HVAC (heating, ventilation, air‐conditioning) operating conditions influence the dissemination of fluorescent tracer particles released in a BCU. Test conditions included normal HVAC operation and exhaust failure resulting in loss of negative pressure. A suspension of optical brightener powder and water was nebulized to produce fluorescent particles simulating droplet nuclei (0.5‐5 μm). Airborne particle number concentrations were monitored by Instantaneous Biological Analyzers and Collectors (FLIR Systems). During normal HVAC operation, fluorescent tracer particles were contained in the isolation room (average concentration = 1 × 10⁴ ± 3 × 10³/L_air). Under exhaust failure, the automated HVAC system maximizes airflow into areas adjacent to isolation rooms to attempt to maintain negative pressure differential. However, 6% of the fluorescent particles were transported through cracks around doors/door handles out of the isolation room via airflow alone and not by movement of personnel or doors. Overall, this study provides a systematic method for evaluating capabilities to contain aerosolized particles during various HVAC scenarios. Recommendations are provided to improve situation‐specific BCU safety.