A Network Game with Attackers and a Defender

Consider an information network with threats called attackers; each attacker uses a probability distribution to choose a node of the network to damage. Opponent to the attackers is a protector entity called defender; the defender scans and cleans from attacks some part of the network (in particular, a link), which it chooses independently using its own probability distribution. Each attacker wishes to maximize the probability of escaping its cleaning by the defender; towards a conflicting objective, the defender aims at maximizing the expected number of attackers it catches. We model this network security scenario as a non-cooperative strategic game on graphs. We are interested in its associated Nash equilibria, where no network entity can unilaterally increase its local objective. We obtain the following results:

Evaluation of dispatching rules for cellular manufacturing

In this paper, the effects of various dispatching rules on the operation and performance of cellular manufacturing systems (CMS) are evaluated. When the study of a CMS considers the automated material handling, it is crucial to reduce the gridlock probability (i.e., the probability of an unsuccessful load transfer attempt occurring in the interface point between the intercell and intracell handling system). Preventing an unsuccessful load transfer is critical for the operation of the entire system as a blockage between the automated guided vehicle (AGV) and the overloaded cell results in a total system shutdown. The gridlock probability is influenced by the dispatching rule used to schedule the load transfers in the system. Therefore, in order to reduce this probability it is necessary to use a dispatching rule that will decrease the number of waiting loads in the transfer spurs. The main objective of the paper presented herein is to identify a dispatching rule that maintains the system operational at all times. A group of dispatching rules, including the first come first served (FCFS), shortest imminent operation (SI), longest imminent operation (LI), most remaining operations (MRO), shortest processing time (SPT), shortest remaining process time (SR), and a newly developed rule proposed by the authors, loads with the minimum number of processing first (MNP), are tested and evaluated with respect to whether the capacity of the transfer spurs of the cells is exceeded. This paper presents a simulation model of a cellular manufacturing system, which is used to further explore the effects of the dispatching rules on the system performance. The results show superior performance of the newly proposed MNP rule.     

The effect of colors of e-commerce websites on consumer mood,memorization and buying intention

This paper aims at studying the effect of the colors of e-commerce websites on consumer mood, memorization and buying intention. On the basis of a literature review a conceptual model is proposed, showing the effects of the color of e-commerce websites and specifically of its components, hue and brightness on the behavioral responses of the consumer, memorization and buying intention. These responses are conveyed by mood. Data collection was carried out during a laboratory experiment in order to control for the measurement of the colored appearance of e-commerce websites. Participants visited one of the eight versions of a website designed for the research, selling music CDs. Data analysis using ANOVA, regressions and general linear models show a significant effect of color on memorization, conveyed by mood. The interaction of hue and brightness, using chromatic colors for the background and foreground supports memorization and buying intention, when contrast is based on low brightness. A negative mood infers better memorization but a decreasing buying intention. Implications for theory and practice are discussed.     

Material characterization and bioactivity evaluation of dental porcelain modified by bioactive glass

This study aimed at the chemical, microstructural and textural characterization of the sol–gel derived dental porcelain modified by bioactive glass and the evaluation of its bioactivity. Sol–gel derived specimens of the composite material were constructed and subjected to firing cycle. Specimens of bioactive glass and dental porcelain served as control. All the specimens were characterized using X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and N₂ porosimetry. The assessment of in vitro bioactivity was carried out by incubating the composite specimens in DMEM solution. Apatite formation was evaluated by SEM/EDS, FTIR and XRD analysis. Microstructural analysis by SEM revealed irregularly shaped particles with broad size distribution, while complex porei network with large pore volume and non-uniform pore size distribution was evident. N₂-adsorption isotherms were representative of non-nano-/meso-porous materials. A mixture of a- and b-wollastonite, apatite and leucite phases were detected by FTIR and Raman spectroscopy. The XRD analysis confirmed the previous results, though traces of cristobalite were identified too. The in vitro tests evidenced the bioactivity of the specimens in a 3-day-period. In conclusion, the physicochemical properties of the sol–gel derived composite result in a bioactive material, though further modifications need to be considered in order to fulfill the requirements of application in the clinical reality.     

Using Multispectral Imaging for Spoilage Detection of Pork Meat

The quality of stored minced pork meat was monitored using a rapid multispectral imaging device to quantify the degree of spoilage. Bacterial counts of a total of 155 meat samples stored for up to 580 h have been measured using conventional laboratory methods. Meat samples were maintained under two different storage conditions: aerobic and modified atmosphere packages as well as under different temperatures. Besides bacterial counts, a sensory panel has judged the spoilage degree of all meat samples into one of three classes. Results showed that the multispectral imaging device was able to classify 76.13 % of the meat samples correctly according to the defined sensory scale. Furthermore, the multispectral camera device was able to predict total viable counts with a standard error of prediction of 7.47 %. It is concluded that there is a good possibility that a setup like the one investigated will be successful for the detection of spoilage degree in minced pork meat.     

Essential oils of the twigs of some conifers grown in Greece

Pinus sylvestris L.), Black pine (P.nigra Arnold) and Fir (Abies Borisii – Regis (Abies alba × A. cephalonica) Mattfeld), grown in natural stands in Greece was investigated. The compounds were identified by GC/MS analysis. The Scots pine oil was found to be rich in α-pinene (19.44%), β-pinene (17.27%), myrcene (14.00%) and β-phellandrene (29.14%). The Black pine oil was also rich in α-pinene (10.38%), β-pinene (15.45%), myrcene (3.99%), β-caryophyllene (4.03%) and citronellol (14.97%), while the Fir oil was rich in α-pinene (3.30%), β-pinene (2.57%), limonene (46.45%), junepene (2.55%) and caryophyllene oxide (7.05%). The mean twig oil yield on dry weight basis was 0.52%, 0.36% and 0.48% for Scots pine, Black pine and Fir respectively.     

Polyurethane/olefinic ionomer blends. 1: Compatibility characterization

The compatibility behaviour of melt-mixed blends of a polyester-type polyurethane (PU) with the Zn²⁺ ionomer of poly(ethylene-co-methacrylic acid-co-isobutylacrylate) terpolymer (Ion., Zn²⁺) was investigated in the complete composition range. The techniques applied were tensile testing, dynamic mechanical analysis (d.m.a.), differential scanning calorimetry (d.s.c.), Fourier transform infrared (FTi.r.) spectroscopy and optical microscopy. Tensile properties were typical of a compatible system and d.m.a. results indicated a miscible blend. FTi.r. results failed to reveal the nature of the specific forces involved in bringing about compatibilization. Analysis of the thermal data obtained allowed the determination of a polymer–polymer interaction parameter which had a near zero value at the elevated temperatures where it was determined.     

Management of networks and services in a composite radio context

This article adopts the assumption that different wireless access technologies (e.g., UMTS, HIPERLAN2, and DVB-T) can be cooperating components of a composite radio infrastructure. The coordinated management of services and network in this heterogeneous context is a complex task. This article presents a service and network resource management platform for wireless systems that operate in a composite radio context. Aspects addressed are the requirements, high-level platform design, functionality of the components that conduct monitoring, resource brokerage, service management, and network resource optimization. Indicative results are presented and concluding remarks provided.     

A New Approach for the Geodesic Voronoi Diagram of Points in a Simple Polygon and Other Restricted Polygonal Domains

We introduce a new method for computing the geodesic Voronoi diagram of point sites in a simple polygon and other restricted polygonal domains. Our method combines a sweep of the polygonal domain with the merging step of a usual divide-and-conquer algorithm. The time complexity is O((n+k) log(n+k)) where n is the number of vertices and k is the number of points, improving upon previously known bounds. Space is O(n+k) . Other polygonal domains where our method is applicable include (among others) a polygonal domain of parallel disjoint line segments and a polygonal domain of rectangles in the L ₁ metric. Received February 15, 1996; revised November 2, 1996.     

Modification of AlN thin films morphology and structure by temporally shaping of fs laser pulses used for deposition

We studied the effect of temporally pulse shaping upon the properties of thin layers synthesized by pulsed laser deposition with fs laser pulses generated by a Ti-sapphire laser source. We showed that the film morphology and structure can be gradually modified when applying mono-pulses of different duration or passing to a sequence of two pulses of different intensities.