Pavement Life-Cycle Cost and Asphalt Binder Quality: Theoretical and Experimental Investigation

Quality control/quality assurance tests can be used to demonstrate that an as-constructed pavement has characteristics different from the contracted specifications of the as-designed pavement because the bitumen employed was of insufficient quality. Many different issues affect asphalt binder quality. Such problems can significantly increase the pavement life-cycle cost, which means that a pay adjustment (PA) is needed. Unfortunately, the quantitative analysis of this issue is very complex. The objectives of this study were to model the dependence of the pavement life-cycle cost on asphalt binder quality and to determine the quantitative relationship between bitumen viscosity and the PA for a given class of boundary conditions. In addition to modeling this problem theoretically, experiments and simulations were carried out through the use of the Mechanistic-Empirical Pavement Design Guide. We then derived the consequences of these effects on life-cycle cost by using a specific life-cycle cost model. Our results demonstrate that asphalt binder viscosity can strongly affect the expected pavement life and the PA, and thus needs to be taken into account in contract and construction management.     

A voltage controlled CMOS current divider with linear characteristic

A compact voltage controlled CMOS current divider is presented. Differently from previous implementations, exploiting the MOSFET translinear characteristics in subthreshold region, the proposed circuit is based on devices operating from moderate to strong inversion. An input current linearity range of nearly a decade is obtained by compensating for the deviations from the ideal drain current square-law approximation through an original empirical approach. The circuit is suitable for use as a building block in analog multipliers and for transconductor continuous tuning. The effectiveness of the proposed configuration is demonstrated by means of electrical simulations, performed on a prototype designed with a commercial process. The robustness of the linearization algorithm with respect to temperature variations is proven.     

Characterization of the interaction layer in diffusion couples U-7 wt.%Mo/Al 6061 alloy at 550 °C and 340 °C.: Effect of the γU(Mo) cellular decomposition

Solid state reaction between U-7 wt.%Mo and Al 6061 alloys at 550 °C and 340 °C was characterized in chemical diffusion couples made by Friction Stir Welding. Results were obtained from optical and scanning electron microscopy, electron probe microanalysis and X-ray diffraction. At 550 °C the interaction layer in γU(Mo)/Al 6061 is formed by U(Al,Si)₃ phase but when γU(Mo) cellular decomposition occurs, UAl₃ and Al₄₃Mo₄U₆ also appear in the interaction layer. At 340 °C the use of X-ray diffraction with synchrotron radiation made it possible to analyze the interaction layer. It was found that it is only formed by U₃Si₅ phase with its cell volume enlarged respect to the original one.     

Theoretical and Experimental Analysis of a Laser Textured Thrust Bearing

In this article, a laser partially textured thrust bearing is theoretically and experimentally analyzed. An adiabatic model is developed in order to theoretically investigate the performances of the bearing. The bearing sample is partially textured both in radial and circumferential direction using the laser texturing process. The performance of the bearing (fluid film thickness and friction torque) is evaluated on a specially adapted test rig and the experimental results are compared with the theoretical model. A good agreement is found between the theoretical model and the experimental data. Also a comparison between a laser textured bearing and a bearing textured using the photolithographic method is presented.     

Morphology and lectin‐binding sites of pyloric caeca epithelium in normal and GnRH‐treated Atlantic bluefin tuna (Thunnus thynnus) Linnaeus 1758

Mucosal epithelium of pyloric caeca was studied in normal and in GnRH‐treated Atlantic bluefin tuna Thunnus thynnus L., using morphological analysis, conventional and lectin glycohistochemistry. The lining epithelium consisted of columnar (absorptive) cells, goblet cells and intraepithelial leucocytes. The epithelium from normal animals was significantly taller than GnRH‐treated samples. Conventional histochemistry displayed the same staining pattern in normal and hormone‐treated specimens which showed a mixture of neutral and sulphated acidic glycoconjugates in the luminal surface and goblet cells, and neutral glycans in apical granules of enterocytes. Lectin histochemistry revealed a different glycoconjugate pattern in normal and GnRH‐treated tunas. In normal specimens the luminal surface expressed sialoglycoconjugates which bound MAL II, SNA, KOH‐sialidase‐PNA, KOH‐sialidase‐SBA as well as asialoglycans stained with HPA, SBA, GSA I‐B₄, LTA. N‐linked glycans were highlighted by Con A and KOH‐sialidase‐WGA. In GnRH‐treated tunas the luminal surface did not react with SNA, SBA and LTA. The columnar cells of normal tunas bound KOH‐sialisase‐PNA in the apical region, KOH‐sialidase‐PNA, KOH‐sialidase‐DBA, HPA, SBA, KOH‐sialidase‐SBA and KOH‐sialidase‐WGA in apical granules, GSA I‐B₄ and LTA in the supranuclear region. GnRH‐treated specimens showed some columnar cells that stained with KOH‐sialidase‐WGA in the apical granules and with GSA I‐B₄ in the supranuclear region. The goblet cells of normal animals produced mucins positive to PNA, HPA, KOH‐sialidase‐DBA, SBA, GSA II. The latter three binding sites lacked in GnRH‐treated tunas. The results suggest that the mucosal epithelium of Thunnus thynnus L. pyloric caeca expresses a complex glycan pattern that is affected by GnRH‐treatment. Microsc. Res. Tech., 2011. © 2010 Wiley‐Liss, Inc.     

Alloying Behaviour of Zinc with Rare Earth Metals: The Er-Pr-Zn System

Zinc based alloys are among the most commonly used light alloys. To improve the knowledge of the ternary systems constituted by zinc with two lanthanides the isothermal section at 400 °C of the Er-Pr-Zn system was studied. Some selected samples at the Er:Pr ratio?=?1:1 were investigated by differential thermal analysis to draw the vertical section of the system. The experimental techniques used were x-ray powder diffraction, scanning electron microscopy, coupled with electron probe microanalysis and differential thermal analysis. No ternary compounds were found in the system. As regard the intermetallic phases, the (Er, Pr)Zn (Er, Pr)Zn₂, (Er, Pr)Zn_3, (Er, Pr)₁₃Zn₅₈ and (Er, Pr)₂Zn₁₇ solid solutions form in the full field of composition, while the ErZn₁₂, Pr₃Zn₁₁ and PrZn₁₁ compounds partially dissolve the third element. The metastable intermetallic binary phases ErZn₅, PrZn₅ and Er₆Zn₂₃ were not found either as ternary solid solutions or as binary compounds in the ternary Er-Pr-Zn system at 400 °C.     

Numerical Studies on the Seismic Retrofit of Bridges Using Shape Memory Alloys

Recent earthquakes have highlighted the seismic vulnerability of bridges due to excessive movements at the joints (in simply supported deck bridges) or concentration of seismic forces in a few piers (in multi-span continuous deck bridges). Steel-based seismic restrainers and viscous shock transmitters are used to limit the joint openings in simply supported deck bridges or to redistribute the seismic force among all piers in continuous deck bridges, respectively. Currently used devices, however, have some limitations such as large dimensions, no energy dissipation, possible large residual displacements, bad control of the force transmitted to the substructure (steel restrainers), large dimensions, difficulty of installation in existing structures, need of maintenance, and sensitivity to the earthquake characteristics (viscous shock transmitters). Shape memory alloys (SMAs) with superelastic behavior show the potential to overcome the limitations involved in the current technologies. In this article, a multi-performance seismic device based on superelastic SMA wires is proposed for the seismic retrofit of multi-span simply supported and continuous deck bridges. The effectiveness of the SMA devices is assessed through a number of nonlinear time-history analyses on two bridge structures representative of existing Italian highway bridges. Results are compared to the seismic response of the bridges in the as-built configuration.     

Multi-agent quality of experience control

International Journal of Control, Automation and Systems - In the framework of the Future Internet, the aim of the Quality of Experience (QoE) Control functionalities is to track the personalized...     

A Novel Function of the Triterpene Squalene in a Tritrophic System

Changes in apple leaf chemistry after infestation by leafminers and their effect on both host location and host habitat location of the generalist parasitoid Pholetesor bicolor were investigated. Chemical analysis of leaf solvent extracts from healthy and leafminer-damaged leaves revealed that herbivory increased the amount of the triterpene squalene (C₃₀H₅₀), whereas quantities of all other identified compounds were similar in both plant treatments. To assess the response of parasitoids to host location cues, contact bioassays were conducted with naïve females. Results showed that parasitoids performed a characteristic ovipositional probing more often on the mine-damaged than on the healthy leaf. This behavior was triggered by a hexane extract of the mine-damaged leaf, but not by a healthy leaf extract. A synthetic mixture of the compounds identified in the extract triggered a similar response. A mixture devoid of squalene was not active, whereas squalene alone elicited the probing behavior. To assess the use of the identified compounds in habitat location, Y-tube olfactometer experiments were conducted with naïve and experienced females. Results showed that squalene is not involved in habitat location and has no priming effect on P. bicolor. While other triterpenes are known to mediate habitat location of parasitoids, this is the first report in which a plant triterpene is shown to mediate host location of a parasitoid. The biological and ecological functions of squalene on all three trophic levels are discussed.