Analysis of a fully bolted moment connection using NONSAP

An analysis of a fully bolted steel beam-to-column moment connection using nonlinear finite element program NONSAP is presented in this paper. The entire assembly of the connection is modeled using two-dimensional isoparametric elements and bar elements. The test results of the full scale specimen are used to calibrate the finite element model. It is shown that the behavior and strength of fully bolted moment connection can be predicted using the proposed finite element model.     

Mechanical Properties of a Uniaxially Reinforced Mullite-Silicon Carbide Composite

Mechanical properties of a mullite ceramic composite uniaxially reinforced with silicon carbide filaments were investigated in flexure mode. Significant improvements in strength and toughness were observed for the composite in comparison to monolithic mullite ceramic. Flexure strength values between 646 and 855 MPa for the composite and between 202 and 271 MPa for the monolithic mullite were obtained. Influence of fiber–matrix interfacial shear stress on the strength, strain to failure, mode of failure, and toughness were studied.     

EXSHOF-II: Active filter design, from approximation function to graphic display of the circuit

This paper presents an expert-system-based package for active filter synthesis, called EXSHOF-II. It starts with approximation function and ends with graphic display of the complete filter circuit. The package is an improved and enhanced version of its mother EXSHOF ( pert system based ynthesis of igh rder ilter). EXSHOF-II gives quantitative and qualitative help at various stages of filter design. Besides the Butterworth, Chebyshev and Elliptic functions which were considered in EXSHOF, the inverse Chebyshev function is also included in EXSHOF-II. For choosing particular approximation EXSHOF-II gives the order of the transfer function. The group delay characteristics of all four approximation functions are plotted on the screen by EXSHOF-II. This aids the user to make a proper choice of an approximation function. Like its mother, EXSHOF-II also considers four high-order structures. The filtering requirement in EXSHOF-II can be directly input on the attenuation characteristics, making the system more user-friendly. The circuit implementation has been done using nine different biquadratic active RC building blocks. The delay requirement can be easily satisfied by cascaded all-pass second-order networks.     

Laminar and turbulent flow continuous interfacial polycondensations of nylon 66

The interfacial polycondensations of nylon 66 in a continuous reaction system have been studied. An experimental stirred flow reactor was used to determine both yield and intrinsic viscosity (molecular weight) as functions of reactant ratio (adipoyl chloride/hexamethylene-diamine), and Reynolds number from laminar to turbulent flow. It was found that mass transfer was the controlling factor in the reaction system. The yield as a function of Reynolds number was found to directly correlate with the behavior of the combination of mass transfer coefficient and interfacial area. Intrinsic viscosity had maximum values in the same reactant ratio range as for batch and continuous cascade systems studied earlier. Intrinsic viscosity behavior was shown to relate to interfacial area behavior.     

Hox9 genes and vertebrate limb specification

Development of paired appendages at appropriate levels along the primary body axis is a hallmark of the body plan of jawed vertebrates. Hox genes are good candidates for encoding position in lateral plate mesoderm along the body axis and thus for determining where limbs are formed. Local application of fibroblast growth factors (FGFs) to the anterior prospective flank of a chick embryo induces development of an ectopic wing, and FGF applied to posterior flank induces an ectopic leg. If particular combinations of Hox gene expression determine where wings and legs develop, then formation of additional limbs from flank should involve changes in Hox gene expression that reflect the type of limb induced. Here we show that the same population of flank cells can be induced to form either a wing or a leg, and that induction of these ectopic limbs is accompanied by specific changes in expression of three Hox genes in lateral plate mesoderm. This then reproduces, in the flank, expression patterns found at normal limb levels. Hox gene expression is reprogrammed in lateral plate mesoderm, but is unaffected in paraxial mesoderm. Independent regulation of Hox gene expression in lateral plate mesoderm may have been a key step in the evolution of paired appendages.     

Synthesis of nanocrystalline α-Al2O3 by ultrasonic flame pyrolysis

Nanocrystalline α-alumina was synthesized in an indigenously built ultrasonic flame pyrolysis (UFP) set-up. This paper describes the technical aspects of the apparatus and particle formation in the flame. Ultrasonically atomized aluminium nitrate dissolved in methanol-water mixture was pyrolyzed in an oxy-propane flame for yielding nanocrystalline α-alumina. The formation of nanophase alumina was confirmed by powder XRD analysis. Scanning electron microscopy (SEM) analysis was carried out to study particulate morphology.     

A critical assessment of the standard molar gibbs free energy of formation of NiWO4

Three independent studies have been reported on the free energy of formation of NiWO₄. Results of these measurements are analyzed by the “third-law” method, using thermal functions for NiWO₄ derived from both low and high temperature heat capacity measurements. Values for the standard molar enthalpy of formation of NiWO₄ at 298·15 K obtained from “third-law” analysis are compared with direct calorimetric determinations. Only one set of free energy measurements is found to be compatible with calorimetric enthalpies of formation. The selected value for Δ_f H _m ⁰ (NiWO₄, cr, 298·15 K) is the average of the three calorimetric measurements, using both high temperature solution and combustion techniques, and the compatible free energy determination. A new set of evaluated data for NiWO₄ is presented.     

An intelligent knowledge-based system for robotic cell design

As research fields in AI accelerate and a greater number of experts are demanded by industry, Expert y tem play an important role in meeting the technological sophistication required in today's competitive world. Industries are demanding the assistance of human experts for solving complicated problems. However, there is a shortage of experts due to this demand. Expert Systems are rapidly becoming one of the major approaches to solve engineering and manufacturing problems. They have been implemented for several practical applications in many decision making problems. Expert Systems are helping major companies to diagnose processes in real time, schedule operations, maintain machinery and to design service and production facilities.

Robots are an integral part of today's manufacturing environment. New tasks are being defined for robots in order to meet the challenges of Flexible Manufacturing Systems. Along with this growth there is an increasing variety of robots to choose from. One of the major problems facing the potential robot user will be his/her choice of an optimum robot for a particular task. Various parameters should be considered and the user should choose an industrial robot whose characteristics satisfy the requirements of the intended task. This paper will present a solution to the problem of selecting an optimum robot by building a Knowledge-Based Expert System. It uses the knowledge base and the rules to determine an optimum robot.     

Differential expression of CD40 ligand on T cell subsets. Implications for different roles of CD45RA+ and CD45RO+ cells in IgE production

Physical contact between human T lymphocytes and B lymphocytes is required for the induction of IgE production. In the present study, we examined the abilities of CD45RA+ and CD45RO+ human T cell subsets to provide help for IgE production by human peripheral blood B cells in the presence of IL-4. Purified peripheral CD45RA+ T cells are much better inducers of IgE synthesis than are CD45RO+ T cells. Activation of CD45RA+ T cells, but not CD45RO+ T cells, via the TCR/CD3 complex is sufficient to confer the ability to provide IgE help, suggesting that an inducible T cell surface molecule plays an important role in this system. The CD40 ligand, an inducible T cell surface molecule, is expressed at higher levels on CD45RA+ T cells as compared with CD45RO+ T cells following CD3-stimulation. Blocking of the CD40-CD40 ligand interaction in vitro by the addition of a soluble form of B cell CD40 Ag completely blocks IgE production induced by CD45RA+ T cells. Finally, the in vitro conversion of CD45RA+ T cells to the CD45RO+ phenotype is accompanied by a loss in the ability of these cells to express the CD40 ligand in response to anti-CD3 stimulation as well as a loss in their ability to provide IgE help. These results suggest that both CD45 subsets may play significant and distinct roles in the induction of IgE production under physiologic conditions: CD45RO+ T cells provide IL-4 and the CD45RA+ subset provides the second signal via the CD40 ligand.