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In recent years, a rapid pace of climate change is becoming evident by a marked increase in the frequency and intensity of weather extremes, and this trend is expected to continue with an increase in global warming for decades to come. The paper presents the non-homogeneous Poisson process as a basis to model an environmental load process induced by non-stationary climate conditions. The distribution of maximum load generated by a non-stationary process is derived, which explicitly accounts for the loading frequency and intensity amplification over time. Using this distribution, structural reliability can be computed for any given time interval in future. The paper shows that traditional measures like the return period, extreme percentiles, and the annual probability of failure, would vary with time under the changing climate. Examples presented in the paper show that a modest amplification of the load magnitude has a drastic negative effect on reliability than that of the frequency of loading. Probabilistic models presented in this paper will be useful in revising currently used "stationary" design codes and ensuring a consistent level of safety in the non-stationary climate. • Non-homogeneous Poisson process for non-stationary reliability analysis. • Consideration of time-dependent frequency and intensity of applied loads. • An accurate, finite time solution for the non-stationary extreme load distribution. • The concept of the return period is not useful in the changing climate. • A modest load amplification has a major negative effect on reliability. [ABSTRACT FROM AUTHOR]

The development of an effective strategy for the inspection and monitoring of the nation's critical bridges has become necessary due to aging, increased traffic loads, changing environmental conditions, and advanced deterioration. This article presents the development of a probabilistic mechanistic modeling approach supported by durability monitoring to obtain improved predictions of service life of concrete bridge decks exposed to chlorides. The application and benefits of this approach are illustrated on a case study of a reinforced concrete barrier wall of a highway bridge monitored over 10 years. It is demonstrated that service life predictions using probabilistic models calibrated with selected monitored field data can provide more reliable assessments of the probabilities of reinforcement corrosion and corrosion-induced damage compared to using deterministic models based on standard data from the literature. Such calibrated probabilistic models can help decision makers optimize intervention strategies as to how and when to repair or rehabilitate a given structure, thus improving its life cycle performance, extending its service life and reducing its life cycle cost. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates the impact of internal curing on the service life of high-performance concrete (HPC) bridge decks by using analytical models to predict the times to onset of corrosion, onset of corrosion-induced damage, and failure of decks. Three bridge deck design options were compared: (i) normal concrete deck; (ii) HPC deck with supplementary cementing materials (SCM); and (iii) HPC deck with SCM and internal curing. It was found that the use of internal curing can extend the service life of high-performance concrete bridge decks by more than 20years, which is mainly due to a significant reduction in the rate of penetration of chlorides in concrete as a result of reduced early-age shrinkage cracking and reduced chloride diffusion. Compared to normal concrete, HPC with SCM and internal curing was predicted to add more than 40years to the service life of bridge decks in severe environmental conditions. Life-cycle cost reductions of 40% and 63% were estimated when conventional HPC and internally-cured HPC were used in bridge decks instead of normal concrete, respectively, despite the fact that the in-place unit cost of internally-cured HPC can be 4% higher than that of conventionally-cured HPC, which in turn can be up to 33% higher than that of normal concrete. This is due to a longer service life and less frequent maintenance activities offered by low-permeability HPC bridge decks. [Copyright &y& Elsevier]

The construction of new bridges and the maintenance and renewal of aging highway bridge network using ultra high performance concrete can lead to the construction of long life bridges that will require minimum maintenance resulting in low life cycle costs. Ultra high performance concrete (UHPC) is a newly developed concrete material that provides very high strength and very low permeability to aggressive agents such as chlorides from de-icing salts or seawater. Ultra high performance concrete could enable major improvements over conventional high performance concrete (HPC) bridges in terms of structural efficiency, durability, and cost-effectiveness over the long term. A simplified design approach of concrete slab on UHPC girders bridge using the Canadian Highway Bridge Design code and the current recommendations for UHPC design is proposed. An illustrative example demonstrates that the use of UHPC in precast-prestressed concrete girders yields a more efficient design of the superstructure where considerable reduction in the number of girders and girder size when compared to conventional HPC girders bridge with the same span length. Hence, UHPC results in a significant reduction in concrete volume and then weight of the superstructure, which in turn leads to significant reduction in the dead load on the substructure, especially for the case of aging bridges, thus improving their performance. La construction de nouveaux ponts ainsi que l’entretien et la réfection du réseau vieillissant des ponts autoroutiers par l’utilisation de béton à très haute performance, peut conduire à la construction de ponts à longue durée de vie qui demanderont un minimum d’entretien, permettant ainsi de faibles coûts du cycle de vie. Le béton à ultra haute performance (BUHP) est un nouveau béton qui fournit une très grande résistance et une très faible perméabilité aux agents chimiques tels que les chlorures provenant des sels de déglaçage et de l’eau de mer. Le BUHP pourrait permettre de grandes améliorations par rapport aux ponts conventionnels en béton haute performance en termes d’efficacité structurale, de durabilité et de rentabilité à long terme. L’article propose une approche simplifiée de conception des dalles de béton sur les ponts à poutres en UHPC en utilisant le Code canadien sur le calcul des ponts routiers et les recommandations courantes sur la conception des ouvrages en BUHP. Selon un exemple présenté, l’utilisation des BUHP dans les ponts en poutres de béton précontraint permet une conception plus efficace de la superstructure, permettant une réduction importante du nombre et de la taille des poutres par rapport aux ponts à poutres conventionnels en béton haute performance de la même portée. Ainsi, les résultats de l’utilisation des BUHP engendrent une réduction importante du volume de béton et, ainsi, du poids de la superstructure. Ceci résulte en une réduction importante de la charge permanente sur l’infrastructure, particulièrement dans le cas des ponts vieillissants, améliorant ainsi leur performance. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we give some results related to interaction mechanism between the elements V such as antimony or phosphorus with the metal indium. We used both powerful spectroscopy methods the Auger electron spectroscopy (AES) and the electron energy loss spectroscopy (EELS) for which the spectra were recorded in direct mode N(E). The antimony was evaporated on pure In metal or on cleaned InP surface involving the In metal because of its cleaning by the argon ion bombardment at low energy 300eV. The antimony flow composed of Sb4 species arrived with a thermal energy on the In metal surface. Such an energy was sufficient to their diffusion into the In matrix because of the low melting point of In metal (123°C). A nucleation phenomenon occurred between Sb4 and the In metal to form small islands of antimony metal in bulk. Further antimony evaporation enabled to increase the size of these islands towards the surface. However, the antimony evaporated on cleaned InP reacted chemically with the In metal distributed on the InP surface to form a thin layer of InSb. The inner stoichiometric layers of InP and the size of Sb4 species and also the stability of InP versus the temperature impeded the interdiffusion phenomenon of antimony to occur deeply into the InP matrix. The InSb layer played the role to stabilise the surface of the InP compound versus the heating at 450°C and the electron irradiation of 4KeV energy. But, the phosphorus evaporation on In metal or on cleaned InP led to form chemical bonds InP. The phosphorus flow included chemical species P and P2 with a thermal energy able to stimulate the chemical reactivity process between indium and phosphorus to form the InP compound. [Copyright &y& Elsevier]

Abstract: This paper presents results of the effect of electron beam irradiation under UHV conditions on InGaAs/GaAs and GaAsN/GaAs systems using Auger electron spectroscopy (AES) and the electron energy loss spectroscopy (EELS) as surface analytical techniques. The ternary compounds In0.53Ga0.47As and In0.2Ga0.8As were irradiated by an electron beam under identical conditions (5KeV; 10−3 Acm−2; for 60min). The results showed that the compound In0.53Ga0.47As was stable under electron irradiation whereas changes in the Auger signal In–M45N45N45 revealed that the electron beam had a significant effect on the compound In0.2Ga0.8As. GaAsN growth at 590°C on GaAs is believed to produce a surface containing defects that is chemically unstable when bombarded by electrons. It was found that heating this compound at 730°C stabilised the surface, protecting it from the effect of electron irradiation. [Copyright &y& Elsevier]

This article proposes a methodology for predicting the time to onset of corrosion of reinforcing steel in concrete bridge decks while incorporating parameter uncertainty. It is based on the integration of artificial neural network (ANN), case-based reasoning (CBR), mechanistic model, and Monte Carlo simulation (MCS). A probabilistic mechanistic model is used to generate the distribution of the time to corrosion initiation based on statistical models of the governing parameters obtained from field data. The proposed ANN and CBR models act as universal functional mapping tools to approximate the relationship between the input and output of the mechanistic model. These tools are integrated with the MCS technique to generate the distribution of the corrosion initiation time using the distributions of the governing parameters. The proposed methodology is applied to predict the time to corrosion initiation of the top reinforcing steel in the concrete deck of the Dickson Bridge in Montreal. This study demonstrates the feasibility, adequate reliability, and computational efficiency of the proposed integrated ANN-MCS and CBR-MCS approaches for preliminary project-level and also network-level analyses. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents an approach to determining the optimal set of maintenance alternatives for a network of infrastructure facilities using genetic algorithms. Optimal maintenance alternatives are those solutions that minimize the life-cycle cost of an infrastructure network while fulfilling reliability and functionality requirements over a given planning horizon. Genetic algorithms are applied to maintenance optimization because of their robust search capabilities that resolve the computational complexity of large-size optimization problems. In the proposed approach, Markov-chain models are used for predicting the performance of infrastructure facilities because of their ability to capture the time-dependence and uncertainty of the deterioration process, maintenance operations, and initial condition, as well as their practicality for network level analysis. Data obtained from the Ministére des Transports du Québec database are used to demonstrate the feasibility and capability of the proposed approach in programming the maintenance of concrete bridge decks. [Copyright &y& Elsevier]

Auger electron spectroscopy and electron energy loss spectroscopy (EELS) have been used to characterize the oxide InPO4 whose thickness is about 10 A˚ as grown on the substrate InP (1 0 0). The behaviour of the surface was studied following either electron irradiation or heating in UHV. The high sensitivity of the EELS, showed a structural change of the surface after irradiation with electrons of 5 keV energy, InPO4 being sensitive to the electron beam. However, this surface oxide appeared to be stable when heated in UHV at 450°C. [Copyright &y& Elsevier]

Building maintenance management involves decision making under multiple objectives and uncertainty, in addition to budgetary constraints. This article presents the development of a multiobjective and stochastic optimization system for maintenance management of roofing systems that integrates stochastic condition-assessment and performance-prediction models with a multiobjective optimization approach. The maintenance optimization includes determination of the optimal allocation of funds and prioritization of roofs for maintenance, repair, and replacement that simultaneously satisfy the following conflicting objectives: (1) minimization of maintenance and repair costs, (2) maximization of network performance, and (3) minimization of risk of failure. A product model of the roof system is used to provide the data framework for collecting and processing data. Compromise programming is used to solve this multiobjective optimization problem and provides building managers an effective decision support system that identifies the optimal projects for repair and replacement while it achieves a satisfactory tradeoff between the conflicting objectives. [ABSTRACT FROM AUTHOR]

Studies the bus bar structure that minimizes wiring inductance in high power IGBT inverter. Role of wiring inductance in limiting the use of inverter; Application of the bus bar technology; Testing of two wiring structures; Techniques that permits low wiring inductance so that no snubber circuits are needed.

We have used Auger and electron energy loss spectroscopy to study the effect of temperature on InGaAs and InPO4 grown on InP. The thickness of InPO4 is of about 10 Å whereas that of InGaAs is of about 800 Å. InPO4 is of great interest because it protects InP from loss of stoichiometry when heated to 450 °C. The InGaAs system heated at 450 °C seems to be unstable; metallic indium appears on the surface in conjunction with formation of GaAs. [Copyright &y& Elsevier]

Highlights: [•] We give an original results about the optical properties of InAs/InP(001) quantum dashes used in optoelectronic devices. [•] The optoelectronic properties of InAs/InP(001) QDas are investigated with photoluminescence spectroscopy. [•] The lateral coupling behavior observed for the nominal sample is completely eliminated in the case of the vicinal sample. [•] The vicinal sample has an excellent thermal stability and a broad emission range. [•] The optical properties of the vicinal sample give the opportunity to use it in solar cells and in infrared photodetectors. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the EELS results revealed the great sensitivity of InP compound submitted to Ar+ or N+ ions at low energy. The preliminary treatment of InP by the Ar+ ions was useful as part of the cleaning process of the surface. Further argon ions bombardment on cleaned InP led however to breaking of chemical bonds In–P, with desorption of phosphorus atoms and appearance of In metal distributed on InP. The damaged InP by Ar+ ions, constituted the diphase (In; InP) system of depth of about 30Å, involving a superficial roughness. The In metal proportion on such a system was determined by a calculation method based on the experimental EELS spectra of pure In and InP. We submitted the heated and no heated system (In; InP) to nitrogen ions bombardment. The nitrogen reacted with the In metal to compensate the phosphorus vacancies so that InN species were formed. The heating of (In; InP) system at 450°C, allowed the surface reconstruction with elimination of defects due to the structure and the roughness. The temperature also caused the coalescence of In metal towards the surface. Because of the physical stability of the interface of heated (In; InP) system, the nitrogen reacted with the outmost layers of In metal to form a homogeneous layer of InN of thickness estimated at 20Å. We associated to the EELS the TRIM (Transport and Range of Ions in Matter) simulation method in order to show the mechanism of interaction Ar+ or N+ ions-InP and determine the disturbed depth as a function of the energy. The EELS alone was not able to give us with accuracy the disturbed depth of the target by these ions. [Copyright &y& Elsevier]

Abstract: The goal of this research is to highlight the effectiveness of associating the spectroscopic methods EELS and EPES in the study of thin film grown on substrates. We use the great sensitivity of the Electron Energy Loss Spectroscopy (EELS) and the Elastic Peak Electron Spectroscopy (EPES) to study native InPO4 oxide of thin thickness (10Å) grown on InP by UV/ozone oxidation. By varying the primary energy of the electron beam and the incidence angle, we give interesting results related to the chemical and the physical analyses of InPO4/InP system. These spectroscopic methods reveal the homogeneity of the chemical composition of InPO4 on the surface. Furthermore, the electron irradiation of InPO4/InP leads to the breaking of chemical bonds between the species of InPO4 and InP to form a new oxide In2O3 on the surface. We show that the heating of InPO4/InP at 450°C in UHV allows a good reconstruction of the surface with elimination of defects on the surface and at the interface. Thus, the surface becomes more stable to impede all oxidation processes due to the electron beam irradiation even for a time as long as 30min. [Copyright &y& Elsevier]

Abstract: The interaction of ions with matter plays an important role in the treatment of material surfaces. In this paper we study the effect of argon ion bombardment on the InSb surface in comparison with the InP one. The Ar+ ions, accelerated at low energy (300eV) lead to compositional and structural changes in InP and InSb compounds. The InP surface is more sensitive to Ar+ ions than that of InSb. These results are directly inferred from the qualitative Auger electron spectra (AES) and electron energy loss spectroscopy (EELS) analysis. However, these techniques alone do not allow us to determine with accuracy the disturbed depth in Ar+ ions of InP and InSb compounds. For this reason, we combine AES and EELS with the simulation method TRIM (transport and range of ions in matter) to show the mechanism of interaction between the ions and the InP or InSb and hence determine the disturbed depth as a function of Ar+ energy. [Copyright &y& Elsevier]

• Updated probabilistic models for the annual maximum wind speed and the ground snow load depth for Canada. • Treated thunderstorm and non-thunderstorm winds in reliability analysis separately. • Calibrated new design wind and snow load and load combination factors for Canadian practice. • Calibrated and recommended load scaling factors accounting for climate change effects for the National Building Code of Canada. In the present study, an updating of the probabilistic models used for calibrating the wind load, snow load and companion load factors for the National Building Code of Canada (NBCC) are presented. The update of probabilistic models for the extreme wind speed and ground snow depth is based on historical climatological data over Canadian sites. For the updating of the statistics of the extreme wind speed, the effect of mixed wind climate (i.e., thunderstorm winds and non-thunderstorm winds) is considered. Reliability analysis is carried out based on this update by considering different load combinations. The results indicate that, for an improved reliability consistency, the use of a high return period to specify the environmental loads and with a unit load factor is preferable to the use of 50 year return period and a load factor greater than one for structural design code making, if the coefficient of variation of the extreme climatological elements is spatially varying. Most importantly, based on these findings and the results from the climate change modelling results, sets of load scaling factors accounting for climate change effects are calibrated for different regions in Canada. Both the use of the target reliability index for a 50-year design working life as well as of the target minimum required annual reliability index within each of the 50-year design working life are considered for the reliability-based calibration. Specific recommendations on the load and companion load factors are suggested for a future edition of NBCC. [ABSTRACT FROM AUTHOR]