Reliability, availability and security of wireless networks in the community

Wireless networking increases the flexibility in the home, work place and community to connect to the Internet without being tied to a single location. Wireless networking has rapidly increased in popularity over recent years. There has also been a change in the use of the internet by users. Home users have embraced wireless technology and businesses see it as having a great impact on their operational efficiency. Both home users and industry are sending increasingly sensitive information through these wireless networks as online delivery of banking, commercial and governmental services becomes more widespread. However undeniable the benefits of wireless networking are, there are additional risks that do not exist in wired networks. It is imperative that adequate assessment and management of risk is undertaken by businesses and home users. This paper reviews wireless network protocols, investigates issues of reliability, availability and security when using wireless networks. The paper, by use of a case study, illustrates the issues and importance of implementing secured wireless networks, and shows the significance of the issue. The paper presents a discussion of the case study and a set of recommendations to mitigate the threat

The influence of arsenic alloying on the localised corrosion behaviour of magnesium

An in-situ scanning vibrating electrode technique is used to investigate the effect of alloyed arsenic on magnesium immersed in chloride containing aqueous solution, both in freely corroding and anodically polarised conditions. Arsenic is shown to strongly suppress cathodic activation of the corroding Mg even under circumstances where breakdown has occurred and subsequent propagation of dark filiform-like tracks is observed. Under galvanostatic anodic polarisation, rates of hydrogen evolution are significantly mitigated compared to pure Mg and no time-dependent evolution of local cathodic sites is detected. The findings support the theory that cathodic activation of the dark corroded Mg surface is associated with accumulated transition metal impurity, which in turn become poisoned towards cathodic hydrogen evolution by the presence of As. In addition, these preliminary studies suggest that alloying with a strong cathodic poison may provide a means of producing a more-charge effective anode material for primary sea-water activated Mg batteries

Inhibition of Localized Corrosion of Hot Dip Galvanized Steel by Phenylphosphonic Acid

Phenylphosphonic acid (H2PP) is investigated as a corrosion inhibitor of hot dip galvanized steel (HDG) fully immersed in a 5% (w/v) sodium chloride electrolyte. An in-situ Scanning Vibrating Electrode Technique (SVET) is used where concentrations of H2PP are systematically added to the electrolyte in neutral conditions. H2PP, at a concentration of 5 × 10−2 mol dm−3, is shown to effectively inhibit localized corrosion over a 24 h period with 96% efficiency. H2PP is compared with a sodium phosphate (Na3PO4) inhibitor at the same concentration over a wide pH range

The influence of Chloride Ion Concentration on Passivity Breakdown in Magnesium

An empirically derived dependence of an apparent breakdown potential (Eb) of magnesium (Mg) on chloride ion concentration is reported. In situations where spontaneous breakdown in the absence of external polarization is observed, leading to the subsequent propagation of localised corrosion, Eb can be determined by following time-dependent changes in free corrosion potential (Ecorr). Breakdown of temporary passivity is marked by a clear inflection in the time-dependent value of Ecorr, characterised by a sharp decrease in potential from a maximum value where Ecorr = Eb. Characterisation of localized corrosion behaviour by in-situ scanning vibrating electrode studies, prior to and following the point of breakdown, is employed to explain the observed Ecorr vs. time characteristics. Examples of typical behaviour upon immersion in aqueous solutions containing different chloride ion concentrations ([Cl-]) are given for commercially pure Mg and an AZ31 alloy. For high purity Mg, which remains passive at pH 11 at all chloride concentrations ≤ 2 mol dm-3, Eb values are determined as a function of chloride ion concentration [Cl-] by means of a potentiodynamic method. In both cases a dependence of Eb on [Cl-] is established such that Eb = A + B log10[Cl-], where the value of B is typically -0.11 V per decade. The practical implications of the existence of a breakdown potential for Mg is considered in terms of the selection of an appropriate chloride ion concentration in standard corrosion tests

Quantifying the Role of Transition Metal Plating in the Cathodic Activation of Corroding Magnesium

This paper examines the effect that transition metal ions have on the corrosion behaviour of high purity magnesium. A series of experiments indicate the ability of the selected transition metal ions to accelerate corrosion through cathodic (re)plating aiming to gain an insight on the Mg corrosion activation described in recent publications. High purity magnesium samples were used in conjunction with known additions of Fe2+, Cu2+, Zn2+ and Mn2+ cations. The results indicate that the presence of transition metal ions in the corrosive electrolyte leads to transition metal (re)plating and to an increase of the magnesium corrosion rate. By systematically varying the transition metal ion concentration it was possible to determine the relative efficiencies of the selected metal cations. It was also observed that the metal (re)plating process and the efficiency of the cathodic activation were limited by the formation of insoluble transition metal (hydr)oxide precipitates and the time-dependent hydrolysis

Anti-viral organic coatings for high touch surfaces based on smart-release, Cu2+ containing pigments

Viruses such as SARS-CoV-2 can remain viable on solid surfaces for up to one week, hence fomites are a potential route of exposure to infectious virus. Copper has well documented antiviral properties that could limit this problem, however practical deployment of copper surfaces has been limited due to the associated costs and the incompatibility of copper metal in specific environments and conditions. We therefore developed an organic coating containing an intelligent-release Cu2+ pigment based on a cation exchange resin. Organic coatings containing a 50 % weight or higher loading of smart-release pigment were capable of completely inactivating (>6 log reduction in titre) SARS-CoV-2 within 4 h of incubation. Importantly these organic coatings demonstrated a significantly enhanced ability to inactivate SARS-CoV-2 compared to metallic copper and un-pigmented material. Furthermore, the presence of contaminating proteins inhibited the antiviral activity of metallic copper, but the intelligent-release Cu2+ pigment was unaffected. The approach of using a very basic paint system, based on a polymer binder embedded with “smart release” pigment containing an anti-viral agent which is liberated by ion-exchange, holds significant promise as a cost effective and rapidly deployed coating to confer virus inactivating capability to high touch surfaces

Smart-release inhibition of corrosion driven organic coating failure on zinc by cationic benzotriazole based pigments

A novel cationic benzotriazole pigment (CBP) based on the benzotriazolium cation (BTAH2+) exchanged into a sulfonated organic resin has been synthesized and evaluated as a means of inhibiting the corrosion-driven cathodic disbondment of organic coatings from the surface of galvanized steel. The CBP is acidic in nature (BTAH2+ pKa ≈ 1.1) and is intended to be compatible with acidic coating formulations such as etch-primers. Delamination rates, as measured using a scanning Kelvin probe (SKP), were found to decrease monotonically with increasing CBP volume fraction (ΦCBP) and to approach zero when ΦCBP = 0.1. The mechanism of CBP operation is described

Direct processing of structural thermoplastic composites using rapid isothermal stamp forming

A novel rapid isothermal stamp forming process is proposed which enables the rapid manufacture of structural thermoplastic composite laminate parts directly from multilayer hybrid fabrics comprising stitched unidirectional carbon fibre-thermoplastic polymer veil. The process employs rapid-response variothermal tooling, allowing macro-scale (fabric forming/draping) and micro-scale (fibre wetting/laminate consolidation) composite material transformation processes to occur isothermally above the constituent polymer matrix melt temperature (Tm), thus manufacturing a composite component directly from a hybrid dry fabric in a single press cycle in a relatively short overall cycle time. The proposed rapid isothermal stamp forming (RISF) concept is presented, and details of the process are given along with some considerations made throughout the formulation of the process. As a result of the RISF process development work, candidate manufacturing parameters were derived, delivering parts that exhibit acceptable composite laminate microstructure and mechanical performance within a press station cycle time of 330 s