The effect of cool paints and surface properties of the facade on the thermal and energy efficiency of buildings in a hot and arid climate

The facade of a building is a decisive factor in the thermal and energy performance of buildings. Its surfaces are considered as zones of heat transfer between the inside and the outside. Surface properties, especially color and texture; which have an important role on solar absorption and thermal emittance of the facade and subsequently the thermal operation of the building. The purpose of this article is to study the impact of surface properties of the facade on the thermal comfort and energy efficiency of buildings in a hot and arid climate. The investigation is based on an experimental approach by taking measurements in test cells with an insulating paint (with nanoparticles) as well as on a numerical study by the dynamic thermal simulation software TRNSYS. Several parameters were studied such as ambient temperature, internal and external surface temperature and energy consumption. The results showed that the surfaces of the facade represent with excellence the place of heat exchange between interior and exterior whose surface properties have a colossal impact on the thermal and energy operation of the building. The insulating paint with its nanoparticles has a considerable impact on the reduction of temperature. The proper choice of material absorption has a great influence on the reduction of temperatures and energy requirements of the building

Service specification and service compliance: How to consider the responsibility dimension?

Service engineering is a huge research topic that addresses the specification, the compliance and the sharing of business and IT services across companies, institutions or governmental organizations. Despite many advantages of working with the services, the guarantee of service compliance and management of the service overlaps by the stakeholders remains challenging. The objective of this document is to present a methodological approach in order to specify the links between the organizational layer and the informational layer of services. Therefore our research has focused on clarifying the responsibility dimension of the stakeholders involved in those services. The proposed approach is illustrated with an example in the context of sensitive data exchange between stakeholders from the healthcare domai

Designing Security Policies for Complex SCADA Systems Protection

The management and protection of these SCADA systems must constantly evolve towards integrated decision making and policy driven by cyber security requirements. The current research stream in this domain aims, accordingly, to foster the smartness of the field equipment which exist through the generic concept of SCADA management and operation. Those components are governed by policies which depend on the components roles, as well as on the evolution of the crisis which also confer to the latter the latitude to react based on their own perception of the crisis evolution. Their latitude is calculated based on the component smartness and is strongly determined by, and depending on, the cyber safety of the component environment. Existing work related to crisis management tends to consider that components evolve and are organized in systems but as far as we know, no systemic solution exists which integrates all of the above requirements. This paper proposes an innovative version of ArchiMate® for the SCADA components modelling purpose to enrich their collaborations and, more particularly, the description of their behavior endorsed in the cyber-policy. Our work has been illustrated in the frame of a critical infrastructure in the field of petroleum supply and storage networks

Modeling and Robust Deflection Control of Piezoelectric microActuators modelled by Zero-Order Numerator Interval System.

International audiencePiezoelectric actuators have received an increasing attention these last years thanks to the high resolution of displacement, high force density and fast response time that can offer piezoelectric materials. However, piezoelectric actuators are highly sensitive to environmental disturbances and typify strong nonlinearities that undeniably reduce the expected positioning accuracy. H1 or μ-synthesis techniques were often used to control these actuators. However, these techniques derive high-order controllers which are hard to implement and that therefore impede the development of real packaged microsystems. This paper aims to design low-order controller ensuring robust performances for piezoelectric actuators. In the approach, first we use a linear model with uncertain parameters that are bounded by interval numbers. Then, on the basis of the interval model and the required performances, a low order controller is computed using a direct synthesis method. The proposed method is suitable for a class of models: transfer functions with zero-order numerator. The experiments confirm the robustness of the proposed method

Interval Modeling and Robust Control of Piezoelectric Microactuators.

International audienceMicrosystems are very sensitive to environmental disturbances (thermal variation, surrounding vibration, microobjects in contact with them, etc.) and they are often subjected to small degradation or their behaviors are often affected during the functioning. As a result, their parameters often change during the micromanipulation, microassembly or measurement tasks and the accuracy or even the stability may be lost. For that, robust control laws should be introduced to control them and to ensure the performance. H1 and μ-synthesis approaches were the classical robust techniques used to control microsystems. They are undeniably efficient but they lead to high-order controllers that are sometimes inconvenient for real-time embedded systems. In this paper, by the means of interval numbers that are used to characterize the uncertain parameters, we propose a method to synthesize simple controllers ensuring robust performance for microsystems. The controller synthesis is formulated as a set-inclusion problem. The main advantages of the proposed method are the ease of modeling the uncertain parameters thanks to intervals and the simplicity and low-order of the derived controllers. The method is afterwards applied to model and control piezoelectric microactuators and the experimental results show its efficiency. Finally, using the H1 technique, we also demonstrate numerically the performance robustness of the closed-loop with the designed controller

Combining H1 and interval techniques to design robust low order controllers: application to piezoelectric actuators.

International audienceThis paper addresses the design of robust controllers for interval systems. For that, the H1-standard approach is combined with interval techniques in order to derive controllers that ensure robust performances. The main advantages of the proposed approach are: 1) the natural and ease of modeling of the uncertain parameters thanks to intervals, 2) the low order of the controller since it can be lower than the order of the system, 3) and the fact that the structure of the controller can be fixed a priori. The paper is particularly focused on the design of a robust PID controller to control systems with order n. Experiments on a piezoelectric actuator (piezocantilever) are carried out and show the efficiency of the proposed method

Study and optimization of the windows’ impact on thermal comfort and energy efficiency (Case of offices in a hot and arid climate)

Controlling the thermal environment and reducing the energy consumption of buildings across the façade are a difficult challenge for architects, especially in a desert climate. The windows in particular play an important role in the tandem of the thermal operation of the building and the comfort of the users. The objective of this article is to study and optimize the impact of windows, their material and proportional characteristics on the thermal comfort and energy efficiency of office buildings in a hot and arid climate. The investigation is based on an empirical approach (measurements taken in situ on real cases) as well as on a numerical simulation study with the TRNSYS program. Several parameters have been studied such as surface temperature, ambient temperature and energy consumption. The results showed that facade windows are a determining factor in the thermal exchanges between the building and its environment and that the key parameters that condition these exchanges are the windows ratio (glazed area) and the type of glazing. The judicious choice of the windows ratio combined with an appropriate choice of the type and composition of the glazing improves the thermal comfort of the users and ensures the energy performance of the building