Modelling of the spring-in phenomenon in curved parts made of a thermosetting composite

In this study, a simple two step finite element model is developed to predict the spring-in of C-sections parts made of AS4/8552 composite. The development of resin properties throughout the MRCC were derived using Group Interaction Modelling and the mechanical properties of the composite predicted by using micromechanical models. Important mechanisms during manufacturing that are effective in the formation of residual stresses and shape distortions are defined. The finite element method implemented is composed of two steps before and after the vitrification of the resin. Vitrification is treated as a point at which the material suddenly changes from the rubbery to glassy state with constant properties in each state. The spring-in angles predicted by the finite element analysis are compared to the angles measured on C-section specimens of various lay-ups and thicknesses. The correlation is good showing the validity of the assumptions adopted.     

The Potential of Asiatic Acid in the Reversion of Cyclophosphamide-Induced Hemorrhagic Cystitis in Rats

The purpose of this study was to determine if asiatic acid may act efficiently in the model of cyclophosphamide (CYP)-induced cystitis in rats. We performed experiments after administration of CYP (single dose 200 mg/kg, intraperitoneally), asiatic acid (30 mg/kg/day for 14 consecutive days, by oral gavage), or CYP plus asiatic acid, during which conscious cystometry, measurements of urothelium thickness and bladder edema, as well as selected biomarkers analyses were conducted. In rats that received asiatic acid together with CYP, a drop in bladder basal pressure, detrusor overactivity index, non-voiding contraction amplitude, non-voiding contraction frequency, and the area under the pressure curve were observed, when compared to the CYP group. Furthermore, a significant increase in threshold pressure, voided volume, intercontraction interval, bladder compliance, and volume threshold to elicit NVC were found in that group accordingly. Administration of the asiatic acid successfully restored concentrations of biomarkers both in bladder urothelium (BDNF, CGRP, OCT-3, IL-1β, IL-6, NGF, nitrotyrosine, malondialdehyde, TNF-α, SV2A, SNAP23, SNAP25, PAC-1, ORM1, occludin, IGFBP-3, HB-EGF, T–H protein, Z01, and HPX) and detrusor muscle (Rho kinase and VAChT) in CYP-treated rats. Finally, asiatic acid significantly decreased urothelium thickness and bladder oedema. Asiatic acid proved to be a potent and effective drug in the rat model of CYP-induced cystitis.     

Design Methodology for Offloading Software Executions to FPGA

Field programmable gate array (FPGA) is a flexible solution for offloading part of the computations from a processor. In particular, it can be used to accelerate an execution of a computationally heavy part of the software application, e.g., in DSP, where small kernels are repeated often. Since an application code for a processor is a software, a design methodology is needed to convert the code into a hardware implementation, applicable to the FPGA. In this paper, we propose a design method, which uses the Transport Triggered Architecture (TTA) processor template and the TTA-based Co-design Environment toolset to automate the design process. With software as a starting point, we generate a RTL implementation of an application-specific TTA processor together with the hardware/software interfaces required to offload computations from the system main processor. To exemplify how the integration of the customized TTA with a new platform could look like, we describe a process of developing required interfaces from a scratch. Finally, we present how to take advantage of the scalability of the TTA processor to target platform and application-specific requirements.     

Characterization of catalysts obtained from rapidly quenched alloy precursors by electrochemical/chemical processes of material degradation—selected examples

Rapidly quenched amorphous alloys—containing metallic or metalloid elements—are precursors for selective catalysts of many technically important reactions. To increase their activity, various methods of material degradation occurring at the surface and in the bulk of the rapidly quenched alloys have been used for promoting the catalytic performance of such materials. The modifications of the structure, composition, and morphology of the substrate proved to be efficient in transforming inactive metal alloy precursors into active and selective catalysts for hydrogenation, and dehydrogenation of organic compounds, as well as for other processes like steam reforming of methanol. This article presents several examples of characterization of such catalysts and discusses their selectivity and activity in a connection with physical and chemical properties of their surfaces. Moreover, it is shown that scanning electron microscopy, Auger electron spectroscopy, scanning Auger microscopy, and energy dispersive spectrometry allowed the local changes occurring during the activation process to be identified and their implications for catalytic function to be considered.     

Resonant measurements of surface resistance of high-Tc superconducting films: How good or bad are they?

Errors in measurements of surface resistanceR _s of HTS materials are due to discrepancy between a mathematical model describing physical phenomena and a real measurement environment, finite accuracy of measurements of theQ-factor, and finite accuracy of constants used for calculation ofR _s . In this paper we analyze errors inR _s due to uncertainties in theQ-factor, geometrical coefficients, loss tangent,R _scu, and other factors when a cylindrical copper cavity with an HTS end plate, a stripline resonator, and sapphire rod resonators are used for HTS characterization.     

Interactive Failure of Two Impacting Beams

A complete analysis of an inelastic beam-to-beam impact is presented. Both beams are of solid, rectangular cross-sections. The problem is formulated based on the momentum conservation and the kinematic and dynamic continuity conditions at the moving wavefront. Closed-form solutions are obtained for transient transverse velocities, deflection profiles, and tensile strains based on the moderately large deflection theory of the beam. Three different regimes of the solution are distinguished, depending on relative values of mass ratios and wave speed ratios. Critical impact velocities to break either of the beams are determined for both the striking and struck beams by assuming both beams fail by tensile necking. However, location of the fracture point depends on relative values of various parameters. It can be right in the contact zone or away from it. It is also shown that after one beam breaks, the other beam will deform further without breaking.     

Optimum deposition conditions of ultrasmooth silver nanolayers

Reduction of surface plasmon-polariton losses due to their scattering on metal surface roughness still remains a challenge in the fabrication of plasmonic devices for nanooptics. To achieve smooth silver films, we study the dependence of surface roughness on the evaporation temperature in a physical vapor deposition process. At the deposition temperature range 90 to 500 K, the mismatch of thermal expansion coefficients of Ag, Ge wetting layer, and sapphire substrate does not deteriorate the metal surface. To avoid ice crystal formation on substrates, the working temperature of the whole physical vapor deposition process should exceed that of the sublimation at the evaporation pressure range. At optimum room temperature, the root-mean-square (RMS) surface roughness was successfully reduced to 0.2 nm for a 10-nm Ag layer on sapphire substrate with a 1-nm germanium wetting interlayer. Silver layers of 10- and 30-nm thickness were examined using an atomic force microscope (AFM), X-ray reflectometry (XRR), and two-dimensional X-ray diffraction (XRD2).

PACS

63.22.Np Layered systems; 68. Surfaces and interfaces; thin films and nanosystems (structure and nonelectronic properties); 81.07.-b Nanoscale materials and structures: fabrication and characterization     

Recalcitrant tumor of the fifth metacarpal bone in a hemodialyzed patient

The article presents a case report about a 38‐year‐old hemodialyzed woman who presented to our department with a painful, expansile, lytic bone lesion of the fifth metacarpal epiphysis. The lesion was resected and replaced by corticocancellous bone graft. At 3 months, imaging suggested signs of graft resorption and local recurrence which necessitated repeat excision and grafting. Because of secondary parathyroidism subsequent subtotal parathyroidectomy was performed. This procedure leads to appropriate bone remodeling by 8 weeks postoperatively, and recurrence has not been observed at 2 years of follow up.     

Reputation as optimality measure in Wireless Sensor Network-based monitoring systems

In this paper we propose a new optimality measure for Wireless Sensor Network-based structural monitoring systems. First, we present the results of experiments showing the reasons for random effects in Wireless Sensor Network (WSN) functioning. Then, the formulas for calculating a network’s reputation measure are given. Finally, we conclude with arguments for the application of the reputation-based optimality measure in WSNs. We propose significantly new recommendations for the design and usage of WSNs.