The extended connection‐dependent threshold model for call‐level performance analysis of multi‐rate loss systems under the bandwidth reservation policy

Firstly, we reviewed two extensions of the Erlang multi‐rate loss model, whereby we can assess the call‐level QoS of telecom networks supporting elastic traffic: (i) the extended Erlang multi‐rate loss model, where random arriving calls of certain bandwidth requirements at call setup can tolerate bandwidth compression while in service; and (ii) the connection‐dependent threshold model, where arriving calls may have several contingency bandwidth requirements, whereas in‐service calls cannot tolerate bandwidth compression. Secondly, we proposed a new model, the extended connection‐dependent threshold model. Calls may have alternative bandwidth requirements at call setup and can tolerate bandwidth compression while in service. We proposed a recurrent formula for the efficient calculation of link occupancy distribution and consequently call blocking probabilities, link utilization, and throughput per service class. Furthermore, in the proposed model, we incorporated the bandwidth reservation policy, whereby we can (i) equalize the call blocking probabilities of different service classes, (ii) guarantee specific QoS per service class, and (iii) implement different maximum bandwidth compression/expansion rate per service class so that the network supports both elastic and stream traffic. The accuracy of the new model is verified by simulation. Moreover, the proposed model performs better than the existing models. Finally, we generalize the proposed model by incorporating service classes with either random or quasi‐random arrivals. Copyright © 2011 John Wiley & Sons, Ltd.     

Preparation and characterization of composite sodium caseinate edible films incorporating naturally emulsified oil bodies

Oil bodies in the form of a naturally emulsified emulsion were recovered from maize germ by applying aqueous extraction and were then exploited in the preparation of composite sodium caseinate-based films. Following equilibration of the initial film-forming dispersion, the caseinate molecules appeared to adsorb to the oil droplet surface facilitating thus the dispersion of the latter in the protein solution. During the course of film formation partial destabilization of oil body dispersion took place as a result of depletion by non-adsorbed caseinate. The finally formed composite films differed from the control, both in their surface characteristics as well in physicochemical and tensile properties. The oil-incorporating films were less transparent, less hydrophilic and, as a result, more resistant to water sorption and vapor permeation than the oil-free caseinate films. In addition, the composite films exhibited higher flexibility and lower stiffness. These findings are discussed in terms of the formation during the drying step of a composite caseinate-based phase separated structure embedded with oil bodies having their surface in intimate association with the protein molecules of the continuous protein matrix.     

A quasi solid-state dye-sensitized solar cell made of polypyrrole counter electrodes

Quasi-solid state dye-sensitized solar cells have been constructed using nanocrystalline titania, a Ureasil-based nanocomposite gel electrolyte and polypyrrole-functionalized counter electrode. Polypyrrole was synthesized by potentiostatic electrodeposition using pyrrole monomer as precursor by a simple procedure in aqueous solution. The thus obtained polypyrrole films were very robust. They were characterized by FE-SEM microscopy and electrochemical impedance spectroscopy and they were used for the construction of solar cells. The employment of polypyrrole electrocatalyst was judged satisfactory for the present application since it was only 30% less efficient than the corresponding counter electrodes functionalized with Pt.     

Using RSS feeds for effective mobile web browsing

While mobile phones are becoming more popular, wireless communication vendors and device manufacturers are seeking new applications for their products. Access to the large corpus of Internet information is a very prominent field. However, the technical limitations of mobile devices pose many challenges. Browsing the Internet using a mobile phone is a large scientific and cultural challenge. Web content must be adapted before it can be accessed by a mobile browser. This work presents a new methodology that uses Really Simple Syndication (RSS) feeds for the adaptation of web content for use in mobile phones. This methodology is based on concrete design guidelines and supports different viewing modes. The mobile tool provided using the RSS feeds is evaluated based on user-centered evaluation and the results are presented.     

Restricted second order information for the solution of optimal control problems using control vector parameterization

A new scheme using a Truncated Newton algorithm with and exact Hessian-search direction vector product is presented for the solution of optimal control problems. The derivation of formulae for second order parametric sensitivity analysis of differential-algebraic equations is presented, following earlier published work [V.S. Vassiliadis, E. Balsa-Canto, J.R. Banga, Second order sensitivities of general dynamic systems with application to optimal control problems. Chem. Eng. Sci. 54 (17) (1999) 3851–3860]. An original result in this work is the derivation of Hessian matrix-vector product forms which are shown to have the same computational complexity as the evaluation of first order sensitivities. This result for optimal control Hessian-vector products using control vector parameterization is shown to be a very effective way to solve optimal control problems. It is also noted that this work introduces the use of suitable Truncated Newton solvers which can exploit the exact vector products in using conjugate gradient iterations to converge the Newton equations. Such a solver is the TN algorithm of Nash [(S.G. Nash-Newton type minimization via the Lanczos method. SIAM J. Num. Anal. 21, (1984) 770–778)]. Because no full Hessian update is necessary it is demonstrated that the resulting optimal control solver performs very well for a very large number of degrees of freedom, limited only by the necessity for many right-hand-side calculations in the first and second order sensitivity equations (the Hessian vector product). It is also demonstrated by several case studies that the scheme is capable of starting far from the solution and yet arrive there in almost invariant performance.     

Energy flow and greenhouse gas emissions in organic and conventional sweet cherry orchards located in or close to Natura 2000 sites

An energy analysis in orchards is useful to deciding best management strategies. The objective of this study was to evaluate, by selecting organic and conventional sweet cherry orchards located in/or close to Natura 2000 sites (a) the energy flow between the two farming systems and (b) the effect of farming system to gas emissions (CO₂, CH₄ and N₂O). Twenty farms [(2-conventional and 2-organic) × 5-locations] were selected during 2003-2004. Means averaged over all locations for insecticides and fungicides application, fuel, insecticides, fungicides, non-renewable energy inputs, energy shoot outputs, energy fruit outputs, energy shoot + fruit outputs, fruit production, shoot efficiency, fruit efficiency, shoot + fruit efficiency, non-renewable energy efficiency, gas emissions were higher in conventional than in organic orchards, while fertilizer application, harvesting, fertilizers, labor, total energy inputs, renewable energy inputs, intensity and non-renewable energy consumption were higher in organic orchards. Means averaged over two farming systems for fertilizer, insecticide and fungicide application were higher in GRL2 and GRL5. The means averaged over two systems for transportation had the highest value in GRL4 and the lowest in GRL5. Finally, means averaged over two farming systems for labor had the highest value in GRL2. Non-renewable energy inputs as percent of total inputs were 82.63 and 52.42% in conventional and organic sweet cherry orchards respectively. The results show that organic farming systems could reduce non-renewable energy inputs and gas emissions in an efficient way in areas related to Natura 2000 sites.     

Structure-radical scavenging activity relationship of alkannin/shikonin derivatives

Alkannins and shikonins (A/S) are naturally occurring isohexenylnaphthazarins (IHNs) of great interest in the field of life sciences due to their broad spectrum of biological properties and are used as food colourants in some countries. In the present study for the first time assessment of the radical scavenging activity of A/S and selected derivatives was carried out using the Crocin Bleaching Assay (CBA) and a modified DPPH assay. Exploration of structure-radical scavenging activity relationship (SAR) was approached with a wide range of A/S derivatives. To accomplish this task, a computational approach was also employed for the two enantiomers and other structurally related compounds. The findings indicated that the side chain –OH group at C-1′ has a positive effect to the radical scavenging properties of alkannin/shikonin by assisting hydrogen atom donation from this carbon atom. Thus, alkannin and shikonin were more potent than deoxyshikonin. Esterification of that hydroxyl group was critical for the activity of the respective compounds (acetyl-, isovaleryl- and β,β-dimethylacryl-shikonin). All of the examined IHN derivatives were found experimentally less potent scavengers than naphthazarin.     

A middleware service for employing and evaluating resource management algorithms in distributed networks

The first part of this paper introduces the design of a middleware‐based service which is valuable for distributed networks for mainly managing their resources. The second part evaluates the performance of a distributed intelligent network (D‐IN), which comprises the proposed service together with a resource management algorithm. We test the network's performance by building and emulating its basic functionality, based on distributed object technology (DOT), in a real environment. The resource management algorithm mainly aims at avoiding congestion and balancing load. Its implementation uses the ICALB algorithm (Comput. Commun. 2002; 25 (17):1548–1556) model. Its incorporation is succeeded through the use and implementation of the distributed middleware‐based service. It is a CORBA‐based service that is used for successfully managing resource management algorithms, such as ICALB, facilitate their operation, and solving classes of problems related to communications over the distributed network, sharing of resources spread over the network, scheduling, synchronization, and management of various tasks. By this means we argue that the method that we use can be employed for operating in various distributed networks. We also evaluate the network's performance by measuring various D‐IN node parameters with critical meaning and by showing the improvements that appeared to the D‐IN from the operation of both the ICALB algorithm and the proposed service. Copyright © 2005 John Wiley & Sons, Ltd.     

Stochastic nucleation and growth of islands on surfaces with the theory of non-classical nucleation

In order to study the irreversible growth and dynamics of islands on surfaces in metal-on (1 0 0) metal homoepitaxy at low temperatures and small coverage, a stochastic element in the theory of non-classical nucleation is introduced. The order parameter is the fractional change in the mass density σ=(ρ−ρ₀)/ρ₀ of the system. The local and non-local free energy densities are functionals of σ. The size distribution of the islands is extracted and compared with the experimental distribution and with the distribution obtained from other simulations. The time dependence of the average island size is also studied. The results are in relatively good agreement with the experimental results and with the results obtained from other simulations.     

Separation and identification of hen egg protein isoforms using SDS–PAGE and 2D gel electrophoresis with MALDI-TOF mass spectrometry

Knowledge of the chemical composition and physicochemical properties of native egg white and yolk is necessary to interpret the functional and biological properties attributed to specific egg components. To date, many of the proteins located in this complex biological fluid remain uncharacterised, if not unknown. High-resolution techniques for proteome analysis, including SDS–PAGE and 2-dimensional (2D) gel electrophoresis, combined with mass spectrometry, were employed to separate and identify several protein components in hen’s egg. An advanced and sensitive glycoprotein staining kit was used to detect the presence of glycosylated proteins in the egg samples. Numerous spots were revealed when a mixture of egg white and yolk was subjected to 2D gel electrophoresis. Several of the already known egg proteins were identified. Isoforms of ovalbumin and conalbumin were visualised. The presence of FLJ 10305 and Fatso proteins in the proteome of Gallus domesticus was also confirmed.