A study of the potential of using the Earth to air heat exchanger for cooling and heating of residential buildings in Iraq

The Earth to air heat exchanger (EAHE) is an effective passive cooling and heating system for buildings. This paper studied numerically the potential for reduction in energy consumption for cooling and heating loads for a residence equipped with an EAHE system in the climate of Nasiriya city, which is located in southern Iraq and at 31.7°N and 45.8°E, latitude and longitude, respectively. Also, this paper presents a study about the thermal performance of three types of EAHE systems, system 1, consisting of one layer of EAHE and buried at an available area of house garden with 3‐m depth, system 2, at the same site of system 1, but with two layers of EAHE at two depths, 3 and 4 m, and finally, system 3, buried along the area of the house at a depth of 3 m. First, the built numerical model was validated against experimental results, and the results of the comparison showed good agreement. The electricity consumption for cooling and heating of the house is calculated with and without the EAHE system. The results showed that with using EAHE, there is a considerable saving in energy and saving in the cost of electricity consumption, which reached 376 329 IQD ($301.11) over 1 year for system 2.     

Post-buckling analysis of piezo-magnetic nanobeams with geometrical imperfection and different piezoelectric contents

Microsystem Technologies - Thermal post-buckling behavior of a geometrically imperfect/perfect piezo-magnetic nano-scale beams made of two-phase composites is analyzed in the present paper based on...     

Nonlinear free and forced vibrations of graphene nanoplatelet reinforced microbeams with geometrical imperfection

Microsystem Technologies - Nonlinear free/forced vibration of a functionally graded graphene nanoplatelet (GNP) reinforced microbeam having geometrical imperfection which is rested on a non-linear...     

Statistical analysis on results of optimal power sharing between linked microgrids

The future distribution network will be made of interconnected distribution systems, so-called microgrids (MGs). MGs provide an effective means of utilising energy from small-scale renewable resources. The probabilistic power generation behaviour renewable generations and load forecasting errors are the most important uncertainties in the MG operation. The proposed methodology of this paper applies these uncertainties into the operation problem in order to find the practical solutions. So, in this research the economic operation of multi-MGs is formulated as a cost-based objective function which is minimised using particle swarm optimisation algorithm. As a result, the problem outputs must be defined by probability distribution functions (PDFs) in order to achieve comprehensive analysis of the literature. Another contribution of the paper, which rises the accuracy of the analysis in operation discussion, is applying suitable fitting criteria to select the best PDF for each obtained result based on Akaike's information criterion.     

Path planning of modular robots on various terrains using Q-learning versus optimization algorithms

Self-reconfigurable modular robots (SRMRs) have recently attracted considerable attention because of their numerous potential applications in the real world. In this paper, we draw a comprehensive comparison among five different algorithms in path planning of a novel SRMR system called ACMoD through an environment comprised of various terrains in a static condition. The contribution of this work is that the reconfiguration ability of ACMoD has been taken into account. This consideration, though raises new algorithmic challenges, equips the robot with new capability to pass difficult terrains rather than bypassing them, and consequently the robot can achieve better performance in terms of traversal time and energy consumption. In this work, four different optimization algorithms, including Adaptive Genetic Algorithm, Elitist Ant System, Dijkstra and Dynamic Weighting A*, along with a well-known reinforcement learning algorithm called Q-Learning, are proposed to solve this path planning problem. The outputs of these algorithms are the optimal path through the environment and the associated configuration on each segment of the path. The challenges involved in mapping the path planning problem to each algorithm are discussed in full details. Eventually, all algorithms are compared in terms of the quality of their solutions and convergence rate.     

Vibration of rotating functionally graded Timoshenko nano-beams with nonlinear thermal distribution

The vibration analysis of rotating, functionally graded Timoshenko nano-beams under an in-plane nonlinear thermal loading is studied for the first time. The formulation is based on Eringen's nonlocal elasticity theory. Hamilton's principle is used for the derivation of the equations. The governing equations are solved by the differential quadrature method. The nano-beam is under axial load due to the rotation and thermal effects, and the boundary conditions are considered as cantilever and propped cantilever. The thermal distribution is considered to be nonlinear and material properties are temperature-dependent and are changing continuously through the thickness according to the power-law form.     

The Effect of Inner Corner Radius of ECAP Die on Strain Distribution and Damage Accumulation in Deformed Sample

In the present research, the effect of inner corner radius of ECAP die on the material flow characteristic and the strain distribution inside sample were analyzed using 2D plain strain finite element simulation. Results showed that increase in inner corner radius results in the formation of smaller corner gap and narrow deformation zone. Consequently, the amount of plastic strain in regions at the bottom side of sample is increased. It is also concluded that the amount of damage factor in the upper regions of sample is higher than bottom regions and therefore cracks may initiate from these regions. In addition, the pressing force was raised by increasing inner corner radius.     

Evaluation of structural,electronic, thermoelectric,and optical results of C-doped HfO2 by first-principle's investigation

In this work, we report the ab initio numerical simulation investigation on the crystal lattice, electronic structure, optical, and transport properties of pure and C-doped crystalline hafnium dioxide (c-HfO₂) using FP-LAPW method. Different exchange correlation functionals like generalized gradient approximation (GGA) of PBE-sol and Tran and Blaha's modified Becke-Johnson exchange potential (mBJ) within density functional theory have been used. Two kinds of defects in cubic pure HfO₂ have been investigated: one is substitution of Hf atom by C impurity and other substitution of O atom by C impurity in crystalline HfO₂. The computed results indicate that impurity energy bands as a result of 2p states of C are found to present in the band gap of c-HfO₂. Few of these bands are present at the conduction band minimum, which results to a noteworthy band gap contraction, and hence electrons close to Fermi level get transferred in doped c-HfO₂. We have also analysed the dielectric function, absorption coefficient, optical conductivity, optical function, electron energy loss, and reflectivity for both pure HfO₂ and doped with C. Furthermore, the temperature-dependent transport properties of C-doped HfO₂ are also discussed in terms of Seeback coefficient, thermal conductivities, electronic conductivities, power factor, and figure of merit in the temperature range 0 to 1200 K. The calculated value of PF for pure HfO₂ was found to increase from 0.01 × 10¹² WK⁻²m⁻¹s⁻¹ at 50 K to 1.79 × 10¹² WK⁻²m⁻¹s⁻¹ at 1200 K and for HfO_{2(1 − x)}C_x it was found to increase from 0.06 × 10¹² WK⁻²m⁻¹s⁻¹ at 50 K to 0.25 × 10¹² WK⁻²m⁻¹s⁻¹ at 1200 K.     

Multi-objective modelling of simultaneous reconfiguration of NMG-based distribution network and operation of different DERs

ABSTRACT

A Micro-Grid (MG) is envisaged with ever increasing distributed energy resources (DERs) e.g. distributed generation, demand response and electrical vehicles. This paper suggests a method based on multi-objective modelling for day-ahead scheduling of Networked-MGs based distribution network in the presence of different DERs and also this method is able to find the daily reconfiguration instants. The proposed scheme is solved using NSGA-II from distribution network operator viewpoints, who is responsible for providing power demand in higher reliability level and lower costs. Besides, in the suggested scheme voltage deviation and voltage stability as efficient power quality criteria in distribution networks and emission pollutant reduction are incorporated as independent objective functions. Moreover, to quantify the influence of different load models, a 33-node distribution network is adopted with a load class mix of residential, industrial and commercial loads. Eventually, the obtained results are reported which verify the efficiency of the proposed method.     

A DFT Study on Structural,Electronic Mechanical and Thermodynamic Properties of 5f-Electron System BaAmO<Subscript>3</Subscript>

The structural, electronic, mechanical and thermodynamic properties of the perovskite oxide BaAmO₃ have been predicted using the full-potential linearized augmented plane wave (FP-LAPW) method. The equilibrium lattice constant, bulk modulus and pressure derivative were computed using different exchange correlations. The optimization of structure was carried out in ferromagnetic, anti-ferromagnetic and non-magnetic states, and the compound was found to be stable in the ferromagnetic state. A systematic study on the band structure and density of states was accomplished using generalized gradient approximation (GGA), Hubbard approximation (GGA + U) and modified Becke–Johnson exchange potential (mBJ),and the compound was found to have a half-metallic nature in all the approximations. The calculated total spin magnetic moment was found to be 5 μ _B in all the approximations used. The second-order elastic constants, Young modulus, shear modulus, Poisson ratio and anisotropic factor have also been calculated. In order to have a complete understanding of BaAmO₃, the thermodynamic properties were studied in the pressure range of 0 to 40 GPa and the temperature range extending from 0 to 600 K.