Individual metering and submetering for cooling application

In 2012 the Energy Efficiency Directive (EED) has set mandatory installation of individual metering and submetering systems for accounting thermal energy consumption in buildings where centralized heating/cooling sources are present, when technically feasible and cost efficient. As a consequence, direct thermal energy meters or indirect heat accounting systems have spread widely in residential buildings, for metering and sub-metering in space heating applications. On the other hand, individual metering of thermal energy in space cooling is a difficult task, due to the very different types of cooling systems and to the lack of technical and legal metrology regulation. In this paper possible solutions available for direct metering and submetering of different types of centralized cooling systems are discussed. Indeed, for direct metering application, the cooling fluid flow metering is a particularly crucial issue due to small pipe diameters and different fluid properties. Thus, the authors carried out an experimental comparison between a Coriolis flow-meter and an ultrasonic clamp-on flow-meter in the cooling fluid circuit of a direct expansion system. Tests have been performed at different operative temperature differences between flow and return, showing relative errors within ± 10%

Derivation of dual horizon state-based peridynamics formulation based on euler-lagrange equation

The numerical solution of peridynamics equations is usually done by using uniform spatial discretisation. Although implementation of uniform discretisation is straightforward, it can increase computational time significantly for certain problems. Instead, non-uniform discretisation can be utilised and different discretisation sizes can be used at different parts of the solution domain. Moreover, the peridynamic length scale parameter, horizon, can also vary throughout the solution domain. Such a scenario requires extra attention since conservation laws must be satisfied. To deal with these issues, dual-horizon peridynamics was introduced so that both non-uniform discretisation and variable horizon sizes can be utilised. In this study, dual-horizon peridynamics formulation is derived by using Euler–Lagrange equation for state-based peridynamics. Moreover, application of boundary conditions and determination of surface correction factors are also explained. Finally, the current formulation is verified by considering two benchmark problems including plate under tension and vibration of a plate

Determination of horizon size in state-based peridynamics

Peridynamics is based on integro-differential equations and has a length scale parameter called horizon which gives peridynamics a non-local character. Currently, there are three main peridynamic formulations available in the literature including bond-based peridynamics, ordinary state-based peridynamics and non-ordinary state-based peridynamics. In this study, the optimum horizon size is determined for ordinary state-based peridynamics and non-ordinary state-based peridynamics formulations by using uniform and non-uniform discretisation under dynamic and static conditions. It is shown that the horizon sizes selected as optimum sizes for uniform discretisation can also be used for non-uniform discretisation without introducing significant error to the system. Moreover, a smaller horizon size can be selected for non-ordinary state-based formulation which can yield significant computational advantage. It is also shown that same horizon size can be used for both static and dynamic problems

Levi-Civita,Tullio

International audienceTullio Levi-Civita (29 March 1873 to 29 December 1941) has been an Italian mathematician and mathematical physicist, known above all for his work on the absolute differential calculus. Levi-Civita came from a rigorous and creative school of mathematical physicists and was a pupil of Gregorio Ricci-Curbastro. LeviCivita’s work included outstanding results in pure and applied mathematics and in celestial and analytic mechanics but also celebrated textbooks. These last, even those written in Italian, have influenced mathematical physicists all over the world.Levi-Civita has perfected some conceptual tools of great importance in modern science, particularly in general relativity, number theory, and continuum mechanics

Electromechanical analysis of an adaptive piezoelectric energy harvester controlled by two segmented electrodes with shunt circuit networks

This paper presents an adaptive power harvester using a shunted piezoelectric control system with segmented electrodes. This technique has spurred new capability for widening the three simultaneous resonance frequency peaks using only a single piezoelectric laminated beam where normally previous works only provide a single peak for the resonance at the first mode. The benefit of the proposed techniques is that it provides effective and robust broadband power generation for application in self-powered wireless sensor devices. The smart structure beam with proof mass offset is considered to have simultaneous combination between vibration-based power harvesting and shunt circuit control-based electrode segments. As a result, the system spurs new development of the two mathematical methods using electromechanical closed-boundary value techniques and Ritz method-based weak-form analytical approach. The two methods have been used for comparison giving accurate results. For different electrode lengths using certain parametric tuning and harvesting circuit systems, the technique enables the prediction of the power harvesting that can be further proved to identify the performance of the system using the effect of varying circuit parameters so as to visualize the frequency and time waveform responses

From Architectured Materials to Large-Scale Additive Manufacturing

The classical material-by-design approach has been extensively perfected by materials scientists, while engineers have been optimising structures geometrically for centuries. The purpose of architectured materials is to build bridges across themicroscale ofmaterials and themacroscale of engineering structures, to put some geometry in the microstructure. This is a paradigm shift. Materials cannot be considered monolithic anymore. Any set of materials functions, even antagonistic ones, can be envisaged in the future. In this paper, we intend to demonstrate the pertinence of computation for developing architectured materials, and the not-so-incidental outcome which led us to developing large-scale additive manufacturing for architectural applications