NetScope: traffic engineering for IP networks

Managing large IP networks requires an understanding of the current traffic flows, routing policies, and network configuration. However, the state of the art for managing IP networks involves manual configuration of each IP router, and traffic engineering based on limited measurements. The networking industry is sorely lacking in software systems that a large Internet service provider can use to support traffic measurement and network modeling, the underpinnings of effective traffic engineering. This article describes the AT&T Labs NetScope, a unified set of software tools for managing the performance of IP backbone networks. The key idea behind NetScope is to generate global views of the network on the basis of configuration and usage data associated with the individual network elements. Having created an appropriate global view, we are able to infer and visualize the networkwide implications of local changes in traffic, configuration, and control. Using NetScope, a network provider can experiment with changes in network configuration in a simulated environment rather than the operational network. In addition, the tool provides a sound framework for additional modules for network optimization and performance debugging. We demonstrate the capabilities of the tool through an example traffic engineering exercise of locating a heavily loaded link, identifying which traffic demands flow on the link, and changing the configuration of intradomain routing to reduce the congestion     

An Inductorless 300 MHz Wideband CMOS Power Amplifier

The power amplifier tends to be one of the most demanding parts to fully integrate when building an entire radio on a CMOS chip. In this paper the design of a fully integrated RF power amplifier without inductors is described. As inductors in CMOS technology are associated with various problems, it is interesting to examine what performance can be achieved without them. An amplifier with an operating band from 60 MHz to 300 MHz (–3 dB) is built in 0.8 m CMOS. A 3 V supply is used. The measured midband power gain is 30 dB with 50 resistive source and load impedance. As linearity is important for many modern modulation schemes, the amplifier is designed to be as linear as possible. The measured third order intercept point is 23 dBm and the 1 dB compression point is 10 dBm, both referred to the output. The output is single ended to avoid an off-chip differential to single ended transformer.     

Long Distance Enhancement of Nonlinear Optical Properties Using Low Concentration of Plasmonic Nanostructures in Dye Doped Monolithic Sol–Gel Materials

Monolithic sol–gel silica composites incorporating platinum‐based chromophores and various types of gold nanoparticles (AuNPs) are prepared and polished to high optical quality. Their photophysical properties are investigated. The glass materials show well‐defined localized surface plasmon resonance (SPR) absorbance from the visible to NIR. No redshifts of the AuNP plasmon absorption peaks due to the increase in nanoparticle doping concentration are observed in the glasses, proving that no or very small SPR coupling effects occur between the AuNPs. At 600 nm excitation, but not at 532 nm, the AuNPs improve the nonlinear absorption performance of glasses codoped with 50 × 10^?3 m of a Pt‐acetylide chromophore. The glasses doped with lower concentrations of AuNPs (2–5 μm average distance) and 50 × 10^?3 m in chromophore, show a marked improvement in nonlinear absorption, with no or only small improvement for the more highly AuNP doped glasses. This study shows the importance of excitation wavelength and nanoparticle concentration for composite systems employing AuNPs to improve two‐photon absorption of chromophores.     

Fracture mechanical analysis of strengthened concrete tension members with one crack

A concrete tension member strengthened with fiber reinforced polymer plates on two sides is analyzed with non-linear fracture mechanics. The analysis of the strengthened tension member incorporates cohesive properties for both concrete and interface between concrete and strengthening medium, and results in closed form solutions for the load-crack opening relationship. To distinguish between single and multiple cracking in a design process, structural classification parameters are derived. The minimum reinforcement ratio for obtaining multiple cracking derived from the structural classification parameters, is investigated in a non-dimensional analysis, and found to depend strongly on the ratio between interfacial and concrete fracture energies.     

Defects in offsite construction: timber module prefabrication

The construction industry is based on craftsmanship. Quality control and assurance procedures applied in manufacturing cannot usually be readily applied in construction, where there are higher degrees of uniqueness in each project. One category of companies, industrialized housebuilders, is attempting to bridge some of the gaps between construction and manufacturing. These companies prefabricate building modules for later assembly at the building site. Since they are wholly responsible for large parts of the building process, these companies have greater opportunities to control and improve quality in a more consistent way than ordinary construction companies. Thus, it could be hypothesized that the frequency and severity of defects should be lower in industrialized housing than in ordinary construction. The aim of the study presented here is to examine this hypothesis by measuring and characterizing defects in industrialized housing. The design and manufacturing processes at two Swedish timber module prefabrication firms has been analysed through interviews, site visits and document reviews. Quality audits from three phases of the building process were compiled, analysed and categorized to provide statistical measures of defects in industrialized housing. The results show that the case study companies are better in terms of product quality than conventional housing.     

A study of a plan-do-check-act method used in less industrialized activities: two cases from industrialized housebuilding

In construction projects, a large number of deviations are usually found during inspections and adjusted in a reactive manner. For projects to become proactive, root causes need to be identified and eliminated as a part of a process of continuous improvement (CI). Plan-do-check-act (PDCA) methods are part of CI and have been used with success within the manufacturing industry for decades. Research studies of PDCA in construction are less common, which could be explained by the past dominance of the project-based nature of construction compared to the process-based nature of manufacture. Industrialized construction, however, has changed this picture somewhat, and it is of interest to find out how well it works for less industrialized activities in construction. A PDCA method was tested in two cases selected from one medium-sized Swedish industrialized housebuilder, which uses a building system based on offsite manufactured modules. Empirical results are based on systematic data gathered through interviews and participant observations. Results from the two cases show that the PDCA method worked even when processes were divided into industrialized parts within a factory and non-industrial parts at the construction site although this might lead to temporary corrective actions rather than permanent process actions.     

Testing the Claims of New Urbanism: Local Access,Pedestrian Travel,and Neighboring Behaviors

This study tests the New Urbanist claims that placing amenities such as parks and retail shops within walking distance of homes will increase pedestrian travel and thereby increase interaction among neighbors. It also examines the relative roles of physical design and personal attitudes and perceptions in predicting walking and neighboring behaviors. Surveys were conducted in eight neighborhoods (four inner-city, four suburban) with varying degrees of local access to parks and shops. Analyses were conducted at the neighborhood and individual levels and were supplemented with qualitative data. The findings provide some support for each of the tested relationships, but also underscore the significance of other variables, especially personal attitudes.     

Formation of biogenic amines in herring and mackerel

The formation of biogenic amines (histamine, cadaverine, putrescine and spermidine) was followed during vacuum packed storage at 2 degrees C or 10 degrees C in the scombroid fish mackerel and in the non-scombroid fish herring. Also the changes in the content of free amino acids and in the organoleptic and microbiological qualities were followed. At 10 degrees C the amine contents were 2-20 times higher at the time of rejection as compared with samples stored at 2 degrees C. In herring and mackerel similar amounts of histamine were accumulated, whilst cadaverine was formed at much higher levels in mackerel compared with herring. The high contents of cadaverine in mackerel can possibly explain why mackerel and not herring are often implicated in incidents of scombrotoxic poisoning.