Dynamic Policy-Based Network Management for a Secure Coalition Environment

This article reports the latest results of an R&D effort to develop a prototype implementation of a dynamic policy-based network management (PBNM) system that can be used to configure and manage a secure network for a coalition environment across an unsecured wide area network. The prototype, based on a distributed architecture, includes capabilities for policy creation and management, dynamic policy negotiation, and dynamic policy provisioning. The policy negotiation facilitates the rapid deployment of a coalition network while the dynamic policy provisioning automates the configuration and management of network services including firewalls, virtual private network connections, routing, quality of service (QoS), and domain name services. Such a PBNM system enhances an organization's ability to react to network incidents identified by a network situational awareness assessment. Although the focus of the current research is a military coalition environment, the system can be used in any distributed enterprise or collaborative environment     

The Effect of Silver Chloride Formation on the Kinetics of Silver Dissolution in Chloride Solution

The precipitation and growth of AgCl on silver in physiological NaCl solution were investigated. AgCl was found to form at bottom of scratches on the surface which may be the less effective sites for diffusion or the favorable sites for heterogeneous nucleation. Patches of silver chloride expanded laterally on the substrate until a continuous film formed. The ionic transport path through this newly formed continuous film was via spaces between AgCl patches. As the film grew, the spaces between AgCl patches closed and ion transport was primarily via micro-channels running through AgCl patches. The decrease of AgCl layer conductivity during film growth were attributed to the clogging of micro-channels or decrease in charge carrier concentration inside the micro-channels. Under thin AgCl layer, i.e. on the order of a micrometer, the dissolution of silver substrate was under mixed activation-Ohmic control. Under thick AgCl layer, i.e. on the order of tens of micrometers, the dissolution of silver substrate was mediated by the Ohmic resistance of AgCl layer.     

A Comparison of Replicate Field Samples Collected with the Bi-Air,Air-O-Cell,and Graesby-Andersen N6 Bioaerosol Samplers

The Bi-Air (BA) and Air-O-Cell (AOC) cassettes have been compared for the collection of Aspergillus/Penicillium (Asp/Pen) and Chaetomium spores based on replicate and/or duplicate samples collected under typical field conditions. Total culturable Asp and Pen concentrations were also compared for the BA and the N6 impactor based on duplicate field samples. When single Asp/Pen spores or small chains were dominant, the average BA:AOC concentration ratio was 2.1 (11,260 spores/m³ v 5,400 spores/m³) for six duplicate samples collected in a well-mixed room. This ratio was consistent with previous studies performed under controlled conditions. However, the average BA:AOC concentration ratio was 54 (765,00 spores/m³ v 36,800 spores/m³) for four replicate samples in which small Asp/Pen spores and clusters of Asp/Pen spores were dominant. The average BA:AOC concentration ratio for Chaetomium was typically 8.6, with a high of 100 for the four replicate samples in which Asp/Pen clusters were dominant. It was concluded that the performance of the BA and the AOC, except for a reasonably constant 2:1 ratio of concentrations, were similar for the detection of single Asp/Pen spores or small chains. However, the BA generally detected higher concentrations of Asp/Pen spores when clusters were dominant; and detected Chaetomium spores in more of the replicate field samples and at a higher average concentration.

The average concentrations of culturable Aspergillus and Penicillium were not statistically different for six duplicate N6 and BA samples collected in a well-mixed room. For nine duplicate field samples with N6 concentrations of total culturable fungi greater than 1,000 cfu/m³, the N6 and BA were moderately correlated (r = 0.76). It was concluded that the ability of the BA to collect culturable fungi was similar to that of the N6 for short-term samples.     

Studies of platinum electroplating baths Part VI: Influence of some experimental parameters on deposit quality

The influence of the conditions on the rate of Pt electroplating and the quality of the deposited layers are reported for the Pt 5Q bath (26mM Pt(NH3)4HPO4 +ap0mM sodium phosphate buffer adjusted to pH 10.4 with NaOH). It is confirmed that much higher rates of deposition can be achieved using constant potential control and the resulting deposits are less stressed than those formed by constant current plating. Deposition with high current efficiency is possible at 358K but again it is more readily achieved at constant potential; the rate of deposition is, however, lower and the plate quality is not as good as observed at 368K. Finally it is reported that three types of deposit can be identified by scanning electron microscopy (almost featureless, hemispherical growth centres leading to cauliflower deposits, and angular crystallites) depending on the cathode potential.     

Fully Coupled 3-D Conjugate Heat Transfer Algorithm for Borehole Heat Exchanger Performance Prediction

Quantitative three-dimensional prediction of the thermal performance of a vertical borehole heat exchanger (BHE) in a ground-source heat pump installation is sought. As BHE installation exhibits exceptionally disparate characteristic length scales, an alternative formation-fluid-thermal fully coupled algorithm is derived to quickly predict the 3-D temperature distributions. The time scale of the steady prediction is of order minutes. This simulation capability can be readily coupled to long-time (order months) unsteady simulation of an entire wellbore field. Algorithm prediction is validated by comparison with data from an instrumented commercial installation for a unique BHE conduit design, followed by illustrative design optimization or variation assessments.     

X-ray Tomography Study on Green State Joining of Silicon Carbide Using Polymer Precursors

X-ray tomography has been used to investigate the density variations in SiC joints formed using polymer pastes. It has been demonstrated that X-ray tomography provides accurate bulk density measurements and volumetric density gradients. The results suggest that the magnitude of the applied pressure after green state joining and the amount of polymer (polycarbosilane, PCS) in the joining pastes influence the green density of the joints. All joints are prepared and applied in air atmosphere and at room temperature. The green densities of the joints increase from 54% to 66% of theoretical with the increase of the applied pressure from ambient to 138 MPa. Highest joint density without applied pressure is achieved using paste containing 50 vol% PCS. Furthermore, allylhydridopopolycarbosilane- (AHPCS-) containing pastes resulted in higher densities at the joint–matrix interface, indicating infiltration of polymer into the matrix.     

THERMODYNAMIC PROPERTIES OF FRACTIONAL DIFFERINTEGRO TYPE CONSTITUTIVE RELATIONS

Abstract

Using the asymptotic properties of Riemann-Liouville form, the intrinsic rate-based first and second laws of thermodynamics properties of fractional differintegro operator type constitutive representations are investigated by illustrating how the conservative and nonconservalive features of the response behavior interact under spectrally rich inputs. Due to the generality of the development, fractional operator representations of any order are considered. This includes the determination of the underlying features giving rise to frequency dependencies in the phasing and amplitude behavior and in this context the irreversible energy release rate process associated with fractional viscoelastic simulations.