Investigation of the corrosion behavior of aluminum bronze alloy in alkaline environment

In this study, the effect of amino-based additives including ammonia, ethanolamine and a mixture of two additives on the pH change of condenser water and corrosion behavior of aluminum bronze alloy as a structural material of condenser were investigated. The results of polarization curves, wheel tests and inductively coupled plasma showed that by increasing the pH from 8.5 to 10.5, the corrosion rate of aluminum bronze alloy and the dissolution rate of alloying elements are increased. The effect of amino-based additives at the same pH is similar to each other. A comparison of corrosion rates determined by polarization curves. The corrosion rates for solutions contained ammonia and ethanolamine additives at pH = 10.5, were 2.92 ⋅ 10⁻² and 4.55 ⋅ 10⁻² mm/y respectively. The wheel test results indicated that the corrosion rates of solutions containing different additives increased to 1.1028 mm/y and 0.4504 mm/y for solutions containing ammonia and ethanolamine, respectively. Therefore, due to similar environmental conditions in the condenser and the wheel test because of the presence perturbation and biphasic fluid, it can be concluded that at pH above 10, aluminum bronze alloy has lower corrosion rate in the cooling water containing ethanolamine than ammonia additives.     

Service-driven traffic engineering for intradomain quality of service management

Quality of service delivery in IP networks is an important area for service providers, pointing to new business opportunities for premium quality traffic. While there has been relevant research on traffic engineering for QoS management, the problem has never been addressed through a holistic approach that brings together service management and traffic engineering. We present an integrated approach to intradomain QoS management that brings together two-level service management and traffic engineering approaches, coupled through the concept of the resource provisioning cycle. We present validation results for MPLS-based traffic engineering through both testbed experimentation and simulation; we also present validation results for monitoring through testbed experimentation. The article updates, enhances, and validates the top-level view of this integrated architecture presented in our earlier paper (see Trimintzios, P. et al., IEEE Commun. Mag., vol.39 no.5, 2001).     

Synthesis and physicochemical characterization of nanostructured Pd/ceria‐clinoptilolite catalyst used for p‐xylene abatement from waste gas streams at low temperature

BACKGROUND: The effect of Pd loading, xylene concentration and GHSV on xylene oxidation was tested over Pd/CeO₂(30%)‐clinoptilolite nanocatalysts at low temperatures. The catalysts were prepared by acid treatment of clinoptilolite, followed by the incipient wetness method of synthesized ceria and modified clinoptilolite in PdCl₂ solution. The synthesized nanocatalysts were characterized by XRD, FESEM, EDAX, TEM, BET, FTIR and TG‐DTG analysis. RESULTS: The XRD patterns confirmed the formation of crystalline ceria with an average crystallite size of 11.8 nm. FESEM images showed nanostructures in cavities of natural zeolite, brought about by ceria incorporation and acid activation. TEM analysis showed high dispersion of Pd with a size distribution between 6.6 and 36.7 nm. The quantitative analysis showed that the specific surface area of Pd(1%)/CeO₂(30%)‐clinoptilolite was 77 m² g^?1. The results showed that Pd(1%)/CeO₂(30%)‐clinoptilolite is the most appropriate catalyst, with the conversion more than 90% at 275 °C. CONCLUSIONS: Experimental results established effective performance and durability for the catalysts. As a result, clinoptilolite modification and ceria incorporation significantly altered the samples' morphology at nanoscale, improving the structure of composites and distribution of noble metals. A reaction path was suggested based on the adsorption‐migration of species to reveal the mechanism of p‐xylene oxidation over nanocatalysts. © 2012 Society of Chemical Industry     

Electrochemical reduction of dioxygen on a thioglycolic acid-capped CdTe quantum dots modified glassy carbon electrode

A novel modified electrode was constructed by immobilizing thioglycolic acid-capped CdTe quantum dots (QDs) on a glassy carbon electrode (GCE) using Nafion ionomers. The results obtained by electrochemical impedance spectroscopy, cyclic voltammetry, and rotating disk electrode using the modified QDs?CNafion/GCE in a 0.20?M phosphate buffer of pH 7.0 revealed that the QDs act as effective mediators for the electrocatalytic reduction of dioxygen.     

Cooperative beamforming in cognitive radio systems without feedback of receiver beamforming vectors to transmitter

Wireless Networks - In this paper, we investigate the problem of transceiver beamforming and power allocation in the downlink of a multiple input multiple output Cognitive radio system. In this...     

Interdomain routing through QoS-class planes [Quality-of-Service-Based Routing Algorithms for Heterogeneous Networks]

This article presents an approach to delivering qualitative end-to-end quality of service (QoS) guarantees across the multiprovider Internet. We propose that bilateral agreements between a number of autonomous systems (ASs) result in the establishment of QoS-class planes that potentially extend across the global Internet. The deployment of a QoS-enhanced border gateway protocol (BGP) with different QoS-based route selection policies in each of the planes allows a range of interdomain QoS capabilities to coexist on the same network infrastructure. The article presents simulation results showing the benefits of the approach and discusses aspects of the performance of QoS-enhanced BGP     

Scalable monitoring support for resource management and service assurance

Continuous monitoring of network status and its resources are necessary to ensure proper network operation. Deployment of QoS-based value-added services in IP networks necessitates the employment of resource management techniques and specifically the use of traffic engineering. The latter typically relies on monitoring data for both offline proactive and dynamic reactive solutions. The variety of data to be collected and analyzed using different measurement methods and tools, and the extent of monitoring information to use demand a proper QoS monitoring infrastructure. A monitoring system should be scalable in terms of network size, speed, and number of customers subscribed to value-added services. This article investigates the requirements of scalable monitoring system architectures, proposes principles for designing such systems, and validates them through the design and implementation of a scalable monitoring system for QoS delivery in IP differentiated services networks. Experimental assessment results prove the accuracy and scalability of the proposed monitoring system.     

Market power analysis for the Iranian electricity market

The market power problem in Iranian electricity market is addressed in this study. This paper by using various structural indices of market power and reviewing market results analyzes the intensity of competition in Iran’s electricity market and examines whether this market is functioning at an appropriate level of efficiency. In this article the most well-known indices of market power are calculated in two approaches for two different scenarios (current situation and future outlook of generation sector’s ownership in Iran’s power industry). Comparing the results of these scenarios promises more competitive market for the second scenario. Calculating Residual Supply Index for Iran’s power market shows despite admissible values of concentration ratios, due to supply scarcity during periods when the demand is close to the total available capacity, some suppliers can exercise market power even with a relatively small market share. The most important price and load indices like weighted average prices and load/price duration curves of Iranian electricity market during March 2007–March 2008 are also analyzed in this paper. These results imply the existence of economic withholding. The main limiting factors of competition and significant implemented countermeasures for market power mitigation in Iran’s electricity market are also mentioned.     

An unexpected spectrum of p53 mutations from squamous cell carcinomas in psoriasis patients treated with PUVA

Photochemotherapy employing 8-methoxypsoralen and long-wavelength ultraviolet radiation (UVA, 320-400 nm) is widely used in the treatment of psoriasis. The photoactivation of psoralens in skin cells leads to formation of DNA photoadducts which may be responsible, at least in part, for the efficacy of these photochemotherapies. However, mutations arising from these adducts may also lead to the well-characterized increased incidence of squamous cell carcinoma. Mutations in the p53 tumor suppressor gene have been detected in many human cancers. To determine whether p53 mutations occur in squamous cell carcinomas in PUVA patients, PCR was used to amplify the exons (5-9) in which other studies have found a high frequency of point mutations. Gel electrophoresis was used to detect single-strand conformational polymorphisms. Aberrantly migrating bands were excised, reamplified and sequenced. Thirty-four specimens from 10 patients were examined. Specimens from one patient who had received no phototherapy as well as from normal controls were also analyzed. Five of the 10 patients showed at least one p53 mutation. In contrast to previously reported psoralen-induced p53 mutations in mice, the expected psoralen type mutations at alternating AT sites were not detected. All but two of the altered sequences occurred at dipyrimidine sites which is typical of solar type mutations. Two C-->T mutations and two dipyrimidine mutations (CC-->TT) were found. Other mutations included: C-->G, G-->T, C-->A and an 18 bp deletion. A review of therapeutic history of these patients showed that some had also received UVB phototherapy. Furthermore, because sunlight is thought to be beneficial for psoriasis, nontherapeutic, casual UVB exposure cannot be excluded. Our observations suggest that the SCC may have arisen from the solar mutations and that PUVA may enhance tumor progression or immune suppression.