Retrofitting of R/C shear walls by means of high performance jackets

A new technique for the strengthening of existing R/C shear walls based on the application of thin high performance jackets is presented in this paper. The strengthening jacket is made of high performance concrete, having a compression resistance higher than 150 MPa, and reinforced by means of an high strength steel mesh. The experimental study is carried out on a 1:3 scale R/C wall, proportioned to resist vertical loads only, and reinforced by means of a 15 mm thick high performance jacket. Cyclic loads of increasing magnitude are applied to the experimental shear wall up to collapse. The effectiveness of the technique is also verified numerically. The results show the efficiency of the proposed solution in significantly increasing the structure resistance, deformation capacity and ductility.     

Transient response analysis and modeling of near wall flow conditions in a micro channel: evidence of slip flow

An experimental tool for determination of the near wall transport parameters in a micro channel, supported by flow simulation, is presented. The method is based on the transient flow response due to convective diffusion, in absence of specific adsorption. An approximately step-function type temporal solute concentration variation serves as the input signal. The associated response signal of a surface plasmon resonance sensor, acting as an integral part of a micro channel, has been taken as the output signal. It provides the flow-dependent change of the NaOH solute concentration in the channel within the optical detection and near wall distance interval 0 < d < 0.5 μm. The temporal signal evolution and response time, until an initially plain aqueous solution is replaced by the solute, varies inversely with solute concentration and flow rate. In the asymptotic limits, the near wall forced convective and diffusive channel transit times, along with the associated velocities, can be extracted and separated. A low convective near wall flow speed would account for 100% adsorption efficiency. The validity of the scaling relation for Fickian diffusive transport has been confirmed by experiments. Convective near wall flow reveals a distorted parabolic flow profile. This indicates relaxation of the no-slip condition, and presence of slip flow. Neither boundary layer formation, nor near wall micro turbulences have been observed. Eventually, a compact mathematical transient flow model, outlined in the Laplace domain for the electrical equivalent analogue circuit and applicable to the convective diffusion equation, has been developed for the flow transients.     

Comparison of Multivariate Control Charts for Process Dispersion

In this article we compare four multivariate control charts for process dispersion in the retrospective analysis of a historical data set. Among the schemes compared, a new control chart based on a robust estimation of the variance-covariance matrix proved to be very effective in detecting changes in the process dispersion matrix.     

Numerical modelling of impact rupture in polysilicon microsystems

A 2D geometrical model for polycrystals was developed in this paper by means of a Voronoi tessellation in which each crystal is assumed to be elastic anisotropic. An implicit–explicit FE dynamic code coupled with an automatic procedure for the introduction of cohesive interface elements with cohesive traction-jump softening laws was used in order to simulate intergranular and transgranular fracture. Accidental drop simulations were performed with the principal aim to capture the maximum acceleration and to simulate local rupture phenomena in MEMS. In order to reduce the excessive problem size, a simplified, decoupled global–local three level multi-scale approach was used.     

Global and local characterization of the thermal diffusivities of SiCf/SiC composites with infrared thermography and flash method

Two types of SiC_f/SiC composites with different matrix quantities are prepared by CVR from pyrolyzed Carbon/resin composites. Experiments based on transient, space-resolved infrared thermography are developed; various assessment methods are implemented to measure simultaneously transverse and in-plane thermal diffusivities, globally and locally; the emphasis is set on the accuracy of the estimations. The material anisotropy is revealed and the influence of matrix volume fraction on the global thermal diffusivities is evaluated. Gradients of the properties are clearly visible in the samples, by use of the local analysis. The global heat conductivity values are discussed with respect to previous works.     

Smooth perturbation on a classical energy function for lossy power system stability analysis

The efforts to find Lyapunov functions for power systems with losses have been until now in vain. Despite that, engineers have been using approximated energy-like functions to obtain good estimates of the critical clearing time (CCT) in transient stability analysis of power systems. These approximated energy-like functions are not Lyapunov functions, and are usually obtained by an integration process followed by an approximation of the integration path. Therefore, the good CCT estimates obtained with these functions are not supported by a sound theory. Nevertheless, it is shown in this paper, for a particular approximated energy-like function, a theoretical approach to support these good estimates. The approximated energy-like function studied in this paper is well known in the literature, and was proposed by Athay et al. in the COA formulation. It is shown that this approximated energy-like function is neither a Lyapunov function in the usual sense, nor an extended Lyapunov function, when the transfer conductances are taken into account. In spite of that, a function attending the requirements of the extension of the Invariance Principle, that is, an extended Lyapunov function, can be obtained by smooth perturbations on that energy-like function. This perturbed function can be used to estimate the attraction area without approximations or conjectures. Indeed, the difference between the proposed extended Lyapunov function and the approximated energy-like function has the order of a smooth perturbation. This fact supports the good CCT estimates that have been obtained using these approximated energy-like functions, and encourages engineers to keep using them for CCT estimates.     

Analysis of average burst-assembly delay and applications in proportional service differentiation

In Optical Burst-Switched (OBS) networks, the limitation of optical buffering devices make it impractical to deploy conventional delay-based differentiation algorithms such as Active Queue Management, Weighted Fair Queuing, etc. Furthermore, only the delay that appears due to the burst-assembly process constitutes a variable quantity (all the other sources of delay are mostly fixed), it is then reasonable to make use of the burst-assembly algorithm to provide class-based delay differentiation. The aim of the following study is twofold: first it defines an average assembly delay metric, which represents the assembly delay experienced by a random arrival at the burst assembler of an edge OBS node; and second, this metric is used to define and configure a two-class burst-assembly policy, which gives preference to high-priority traffic over low-priority packet arrivals. The results show that, (1) tuning the parameters of the two-class assembly algorithm, the two classes of traffic exhibit different burst-assembly delay; and, (2) such parameters can be adjusted to provide a given differentiation ratio in the light of the proportional QoS differentiation approach proposed in the literature. A detailed analysis of the two-class assembly algorithm is given, along with an exhaustive set of experiments and numerical examples that validate the equations derived.     

Cost and Schedule Monitoring of Industrial Building Projects: Case Study

Performance measurement is a helpful tool for taking corrective actions and controlling a project as far as this enables accurate time and cost forecasts during the first stages of the construction effort when the management team still has opportunities to make adjustments. This paper overcomes the dilemma of practicability and predictability of traditional estimates at completion based on early progress measurement by presenting the empirical results from the construction project of an industrial facility. The case may be a reference practice for assessing time and cost performance measurement of any building, whose layout can be reasonably partitioned into repeatable portions. In such circumstances, an effectively-managed traditional earned value method and appropriate metrics for computing performance provide project managers with accurate forecasts as useful tools for successful project management and control.     

Direct heat transfer considerations for improving energy efficiency in pulp and paper Kraft mills

The success of any process improvement study depends on the quality of the available data and the way in which the plant-specific characteristics are incorporated in the applied conceptual models; in the context of process integration studies these issues are directly related to the rules followed during the data extraction stage. Improving energy efficiency in a pulp and paper Kraft mill requires the identification of the most promising heat recovery network retrofit projects. In a retrofit analysis using pinch technology/process integration methods, only the process streams associated to the existing heat exchangers and some outlet streams (such as wastewater/effluent streams and vents) with high potential for heat recovery are usually included, while the energy exchanged through non-isothermal stream mixing (NIM) or direct heat transfer (DHT) is often assumed fixed and is not considered in the analysis. Relaxing this assumption requires extracting more data to represent the DHT design configuration that exists in the plant. However, different data extraction options can be considered to represent the DHT configuration depending on the associated process/operation constraints. This work describes a systematic procedure to extract and analyse the impacts of DHT on the overall energy efficiency of a Kraft process with a specific focus on mixing along the pulp line and in water tanks.     

Implementing Bologna in Southern European countries: Comparative analysis of some research findings

From the European and national perspectives the analysis of policy implementation tends to focus on aspects related to the legal framework. At these levels, institutions offer “the vision of a triumphant march towards the objectives set for 2010” [Veiga, A., Amaral, A., 2006b, The open method of co-ordination and the implementation of Bologna process. Tert Educ Manage, 12(4): 283–295]. There are several factors influencing this perspective: policy implementation is viewed as a linear process, which is an outdated perspective and obscures a number of interlocking dimensions; the political time is not aligned with the academic time, preventing a reform in substance and the competitive emulation practices emphasising the role of performance indicators stress the economic dimension [Neave, G., 2005, On snowballs, slopes and the process of Bologna: some testy reflections on the advance of higher education in Europe, ARENA—Centre for European Studies, University of Oslo; Veiga, A., Amaral, A., 2006b, The open method of co-ordination and the implementation of Bologna process. Tert Educ Manage, 12(4): 283–295]. From the local perspective, the perceptions show that higher education institutions (HEIs) often use alternative interpretations of Bologna that suit their institutional strategies.

In this paper, the implementation is analysed using as empirical data the stocktaking exercises [Bologna Follow-up Group, 2005, Bologna process stocktaking report, in: Ministerial Meeting in Bergen, Bergen; Bologna Follow-up Group, 2007, Bologna process stocktaking report, in: Ministerial Meeting in London, London] and the material collected in two research projects (the UNIMON project [Moscati, R., 2006, University change: Italy and Europe, in: Monitoring the Reform of the Higher Education System in Six Italian Universities, Final Results, University of Milano-Biccoca, Milan] and the survey involving all Portuguese higher education institutions that presented new degree programmes or adaptations to the Bologna-type structure).

The paper starts by providing the broad context of the Bologna process putting emphasis on the instruments that have been used to steer the agenda. The analysis of policy implementation is based on both the depiction of policy contexts of Southern European countries and on the confrontation of the stocktaking results with those contexts to conclude that the initiative lies at present with the HEIs.