Conformal Collineations and Ricci Inheritance Symmetry in String Cloud and String Fluids

Conformal collineations (a generalization of conformal motion) and Ricci inheritance collineations, defined by $\pounds_\xi R_{ab}=2\alpha R_{ab}$, for string cloud and string fluids in general relativity are studied. By investigating the kinematical and dynamical properties of such fluids and using the field equations, some recent studies on the restrictions imposed by conformal collineations are extended, and new results are found.Comment: 12 pages, LaTeX, no figures, to appear in Int. J. Mod. Phys.

Three-dimensional unstructured method for flows past bodies in 6-DOF relative motion

A three dimensional, unstructured-mesh methodology was developed to simulate unsteady flows past bodies in relative motion, where the trajectory was determined from the instantaneous aerodynamics. The method coupled the equations of fluid flow and those of rigid-body dynamics, and captured the time-dependent interference between stationary and moving boundaries. The unsteady, compressible Euler equations were solved on dynamic, unstructured meshes by an explicit, finite-volume, upwind method. The grid adaptation was performed within a window placed around the moving body. The Euler equations of dynamics were solved by a Runge-Kutta integration scheme. The flow solver and the adaptation scheme were validated by simulating the transonic, unsteady flow around a wing undergoing a forced, periodic pitching motion, then comparing the results with the experimental data. To validate the trajectory code, the six-degrees-of-freedom (DOF) motion of a store separating from a wing was computed using the experimentally determined force and moment fields, then comparing with an independently generated trajectory. Finally, the overall methodology was demonstrated by simulating the unsteady flowfield and the trajectory of a store dropped from a wing. The methodology, its computational cost notwithstanding, has proven to be accurate, automated, easy for dynamic gridding, and relatively efficient for the required man-hours

Design Optimization Module For Hierarchical Research and Learning Environment

The present paper describes a learning module on design optimization courses within a hierarchical research and learning network (HRLN). In this environment a knowledge organization can be created as a hierarchical learning network to link diverse inter- and trans- disciplinary teams from a consortium of universities, industry, government agencies and the providers of learning technologies. It is an approach that builds on computer-based training, intelligent tutoring systems, interactive learning, collaborative-distributed learning, and learning networks. The present design optimization module has been developed and described herein, as a demonstrator of a learning module in this environment. This module allows for the learners of design optimization to get the course material at their own convenience and time either via the internet or packaged files. Consequently, it is expected that the learner’s ability to understand design optimization and review its pertinent details will be enhanced significantly

Preparation of high surface area activated carbon from waste-biomass of sunflower piths: Kinetics and equilibrium studies on the dye removal

Sunflower pith (SP), a vast agricultural waste is herein used as a precursor material for highly porous low density activated carbon production. Porosity and flake-like microstructure of the SP in its natural form are shown by micro-computed tomography (Micro-CT). Carbonization process turns the SP into thin, separated carbon flakes of 200 nm thickness. Two types of alkaline based chemical activation with KOH and NaOH are performed to yield SP based activated carbon (AC), K-SPAC and N-SPAC, respectively. Microstructural changes upon carbonization and activation process are elaborated by RAMAN, FTIR and SEM analyses. BET Surface area of the NaOH-activated N-SPAC was calculated as 2690 m2/g and was higher than KOH-activated K-SPAC with 2090 m2/g. Maximum adsorption capacity of N-SPAC was calculated as 965 mg/g whereas it was 580 mg/g for K-SPAC. Adsorption kinetic studies for N-SPAC revealed that at a low initial concentration of dye (500 mg/L), the pseudo first-order kinetic model was predictive. On the other hand, at high initial MB concentration (1000 mg/L), the results indicate that the adsorption kinetics follow the Elovich model with intraparticle diffusion as one of the rate-determining steps. In conclusion, overall results suggest that thanks to its highly porous microstructure, the SP is an alternative renewable AC precursor choice for dye removal applications

A Recurrent Stop-Codon Mutation in Succinate Dehydrogenase Subunit B Gene in Normal Peripheral Blood and Childhood T-Cell Acute Leukemia

BACKGROUND: Somatic cytidine mutations in normal mammalian nuclear genes occur during antibody diversification in B lymphocytes and generate an isoform of apolipoprotein B in intestinal cells by RNA editing. Here, I describe that succinate dehydrogenase (SDH; mitochondrial complex II) subunit B gene (SDHB) is somatically mutated at a cytidine residue in normal peripheral blood mononuclear cells (PBMCs) and T-cell acute leukemia. Germ line mutations in the SDHB, SDHC or SDHD genes cause hereditary paraganglioma (PGL) tumors which show constitutive activation of homeostatic mechanisms induced by oxygen deprivation (hypoxia). PRINCIPAL FINDINGS: To determine the prevalence of a mutation identified in the SDHB mRNA, 180 samples are tested. An SDHB stop-codon mutation c.136C>T (R46X) is present in a significant fraction (average = 5.8%, range = less than 1 to 30%, n = 52) of the mRNAs obtained from PBMCs. In contrast, the R46X mutation is present in the genomic DNA of PBMCs at very low levels. Examination of the PBMC cell-type subsets identifies monocytes and natural killer (NK) cells as primary sources of the mutant transcript, although lesser contributions also come from B and T lymphocytes. Transcript sequence analyses in leukemic cell lines derived from monocyte, NK, T and B cells indicate that the mutational mechanism targeting SDHB is operational in T-cell acute leukemia. Accordingly, substantial levels (more than 3%) of the mutant SDHB transcripts are detected in five of 20 primary childhood T-cell acute lymphoblastic leukemia (T-ALL) bone marrow samples, but in none of 20 B-ALL samples. In addition, distinct heterozygous SDHB missense DNA mutations are identified in Jurkat and TALL-104 cell lines which are derived from T-ALLs. CONCLUSIONS: The identification of a recurrent, inactivating stop-codon mutation in the SDHB gene in normal blood cells suggests that SDHB is targeted by a cytidine deaminase enzyme. The SDHB mutations in normal PBMCs and leukemic T cells might play a role in cellular pre-adaptation to hypoxia

Spacelike Ricci Inheritance Vectors in a Model of String Cloud and String Fluid Stress Tensor

We study the consequences of the existence of spacelike Ricci inheritance vectors (SpRIVs) parallel to $x^a$ for model of string cloud and string fluid stress tensor in the context of general relativity. Necessary and sufficient conditions are derived for a spacetime with a model of string cloud and string fluid stress tensor to admit a SpRIV and a SpRIV which is also a spacelike conformal Killing vector (SpCKV). Also, some results are obtained.Comment: 11 page

Discovering Software Process Deviations Using Visualizations

Peer reviewe

The Open Assembly Model for the Exchange of Assembly and Tolerance Information: Overview and Example

In early design phases an effective information exchange among CAD (Computer Aided Design) tools depends on a standardized representation for the product data in all PLM (Product Lifecycle Management) tools. The NIST Core Product Model (CPM) and its extension are proposed to provide the required base-level product model that is open, non-proprietary, generic, extensible, independent of any one product development process and capable of capturing the full engineering context commonly shared in product development [1]. The Open Assembly Model (OAM) Model extends CPM to provide a standard representation and exchange protocol for assembly. The assembly information model emphasizes the nature and information requirements for part features and assembly relationships. The model includes both assembly as a concept and assembly as a data structure. For the latter it uses the model data structures of ISO 10303, informally known as the Standard for the Exchange of Product model data (STEP)[2]. The objective of the paper is to show how the OAM can be used to realize seamless integration of product information, with an emphasis on assembly, throughout all phases of a product design. A gearbox design example is used to illustrate the process

The Open Assembly Model for the Exchange of Assembly and Tolerance Information: Overview and Example

In early design phases an effective information exchange among CAD (Computer Aided Design) tools depends on a standardized representation for the product data in all PLM (Product Lifecycle Management) tools. The NIST Core Product Model (CPM) and its extension are proposed to provide the required base-level product model that is open, non-proprietary, generic, extensible, independent of any one product development process and capable of capturing the full engineering context commonly shared in product development [1]. The Open Assembly Model (OAM) Model extends CPM to provide a standard representation and exchange protocol for assembly. The assembly information model emphasizes the nature and information requirements for part features and assembly relationships. The model includes both assembly as a concept and assembly as a data structure. For the latter it uses the model data structures of ISO 10303, informally known as the Standard for the Exchange of Product model data (STEP)[2]. The objective of the paper is to show how the OAM can be used to realize seamless integration of product information, with an emphasis on assembly, throughout all phases of a product design. A gearbox design example is used to illustrate the process

Global Optimization by Basin-Hopping and the Lowest Energy Structures of Lennard-Jones Clusters Containing up to 110 Atoms

We describe a global optimization technique using `basin-hopping' in which the potential energy surface is transformed into a collection of interpenetrating staircases. This method has been designed to exploit the features which recent work suggests must be present in an energy landscape for efficient relaxation to the global minimum. The transformation associates any point in configuration space with the local minimum obtained by a geometry optimization started from that point, effectively removing transition state regions from the problem. However, unlike other methods based upon hypersurface deformation, this transformation does not change the global minimum. The lowest known structures are located for all Lennard-Jones clusters up to 110 atoms, including a number that have never been found before in unbiased searches.Comment: 8 pages, 3 figures, revte