Thermal OH (1667/65 MHz) Absorption and Nonthermal OH (1720 MHz) Emission Towards the W28 Supernova Remnant

The W28 supernova remnant is an excellent prototype for observing shocked gas resulting from the interaction of supernova remnants (SNRs) and adjacent molecular clouds (MCs). We present two new signatures of shocked molecular gas in this remnant. One is the detection of main-line extended OH (1667 MHz) absorption with broad linewidths. The column density of OH estimated from the optical depth profiles is consistent with a theoretical model in which OH is formed behind a C-type shock front. The second is the detection of extended, weak OH (1720 MHz) line emission with narrow linewidth distributed throughout the shocked region of W28. These give observational support to the idea that compact maser sources delineate the brightest component of a much larger region of main line OH absorption and nonthermal OH (1720 MHz) emission tracing the global structure of shocked molecular gas. Main line OH (1665/67) absorption and extended OH (1720 MHz) emission line studies can serve as powerful tools to detect SNR-MC interaction even when bright OH (1720 MHz) masers are absent.Comment: 14 pages, 3 figures, one table, to appear in ApJ (Jan 10, 2003

Deriving the Hirshfeld partitioning using distance metrics

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A two-level method for calculation of microstress on reinforced plates with circular hole in case of extension normal to principal direction

The stress concentration must often be examined at two levels while analyzing the stress condition of composite materials. The macroconcentration depends on the presence of holes, notches and other local areas of a construction. Typical dimensions of macroconcentration distribution areas are of the order of 0,01–0,1 m. Macroconcentration analysis is performed using the models of homogeneous material. Microstress concentration occurs in structurally inhomogeneous composites due to the structural heterogeneity of the composite. The sizes of concentration areas in regular structures are defined by the sizes of periodically recurring areas. In fibrous composites, such areas have the size of approximately 0,0001 m or less. This makes it necessary to use a two-level approach for the analysis of the stress concentration in the construction of composite materials. The aim of the present study was to compute the stress concentration in unidirectional reinforced composite plate with circular hole with respect to the volume ratio of the component materials in composite. The contour of the circular hole and its dependency on the structure of plates was calculated in order to study the behaviors of macro- and microstresses. The boundary conditions at a large distance from the hole are pressure, uniformly distributed on the plate. Also this problem is analyzed with the finite element method by package ANSYS. Macroconcentration is defined based on the solution of the plane problem of elasticity theory of the orthotropic material by the virtue of functions of a complex variable. The finite element method was used to investigate the stress distribution at microlevel. Boundary conditions that model the state of the specified twodimensional representative cell in the composite structure were established. The results demonstrated the macro- and microstresses and behavior of the orthotropic plate with a circular hole calculated for two different structures

Introduction to the special issue on generalisation from dialogical single case studies

Drawing on historical, theoretical and cultural knowledge, this introduction explains and justifies the importance of generalisation from dialogical single case studies. We clarify the meaning of dialogism and dialogicality, differentiate between single case studies and dialogical single case studies, identify the dynamic and ethical features of dialogical single case studies, and articulate the problem of generalisation as it pertains to this topic. We suggest that the question of generalisation ought to be viewed as an effort to resituate knowledge and its dialogical features, for example values, ethical standards or levels of engagement, in other dialogical single case studies

The calculation of effective elastic constants in a composite with 3D orthogonal nonwoven fibers

The paper is devoted to the research of the effective characteristics of 3D orthogonal nonwoven fibers composites. The results were received via ANSYS software package. In this research a volume element of fibers in cubic unit cell is considered. The effective elastic properties of fiber reinforced composite have been defined by the numerical stress analysis of the unit cell

A New Numerical Method for Calculation of Micro- Stress on Unidirectionally Reinforced Plates with Circular Hole In Case of Extension to a Principal Direction

The aim of the present study was to compute the stress concentration in reinforced composite plate with circular hole with respect to the volume ratio of the component materials in composite. The contour of the circular hole and its dependency on the structure of plates were calculated in order to study the behaviors of macro and micro-stresses. The boundary conditions at a large distance from the hole are pressure, uniformly distributed on the plate. Also this problem is analyzed with the finite element method by package ANSYS. The results demonstrated the macro and micro stress and behavior of the orthotropic plate with a circular hole calculated for two different structures

A New Numerical Procedure for Determination of Effective Elastic Constants in Unidirectional Composite Plates

In this paper a composite plate with similar unidirectional fibers is considered. Assuming orthotropic structure, theory of elasticity is used for investigating the stress concentration. Also, complex variable functions are utilized for solving the plane stress problems. Then the effective characteristics of this plate are studied numerically by using ANSYS software. In this research a volume element of fibers in square array is considered. In order to investigate the numerical finite element modeling, the modeling of a quarter unit cell is considered. For determining the elasticity coefficients, stress analysis is performed for considered volume with noting to boundary conditions. Effective elasticity and mechanical properties of composite which polymer epoxy is considered as its matrix, are determined theoretically and also by the proposed method in this paper with finite element method. Finally, the variations of mechanical properties with respect to fiber-volume fraction are studied

Knowledge discovery for friction stir welding via data driven approaches: Part 2 – multiobjective modelling using fuzzy rule based systems

In this final part of this extensive study, a new systematic data-driven fuzzy modelling approach has been developed, taking into account both the modelling accuracy and its interpretability (transparency) as attributes. For the first time, a data-driven modelling framework has been proposed designed and implemented in order to model the intricate FSW behaviours relating to AA5083 aluminium alloy, consisting of the grain size, mechanical properties, as well as internal process properties. As a result, ‘Pareto-optimal’ predictive models have been successfully elicited which, through validations on real data for the aluminium alloy AA5083, have been shown to be accurate, transparent and generic despite the conservative number of data points used for model training and testing. Compared with analytically based methods, the proposed data-driven modelling approach provides a more effective way to construct prediction models for FSW when there is an apparent lack of fundamental process knowledge

Development of a conductive photoresist with a mixture of SU-8 and HCL doped polyaniline

A novel electrically conductive photoresist has been formulated to fabricate microcomponents. The developed conductive photoresist is based upon SU-8 photopolymer, an insulating negative-tone epoxy, in which protonically doped polyaniline (PANI) nanoparticles have been dispersed to enhance the electrical properties. The characteristics of this new conductive photoresist have been studied via electrical measurements. The process for preparing the conductive films from the combination of EB (Emeraldine base) PANI, SU-8 and NMP (N-methyl-2-pyrrolidinone) will be presented. Different weight percentages (wt%) of SU-8 in the above combination have been prepared and spin coated to form thin-films which have been protonated with HCl. The conductivities of the thin- films were measured using a four point probe. The highest conductivity achieved was approximately 1.6 S/cm for the mixture of 10 wt% of SU-8 25 with EB-PANI mixed with NMP. The morphology of the thin-films was studied using a scanning electron microscopy (SEM)