Simulating the structure and air permeability of needle-punched nonwoven layer

The aim of this article is to study and simulate the structure of needle-punched nonwoven fabrics in order to predict air permeability of nonwoven filters. For this purpose, the Poisson’s random number process has been used to model the random position of fibers in a web. A simple and easy-to-use expression was developed to predict the number of webs in a layer, considering the thickness and areal density of nonwoven fabrics. A 3D model was generated by assembling simulated webs. The GAMBIT meshing software was used to generate the mesh for the Computational Fluid Dynamic (CFD) solver. The outlet pressure of generated model was determined by means of CFD tool. Different types of needle-punched nonwoven fabrics were produced using Polyester fibers with different cross section and counts. The air permeability test was carried out on the samples, and the outlet pressure of each sample were measured and compared with theoretical values. The results showed that the simulated structure is capable to predict the air permeability of nonwoven filters adequately. The main novelty of the model is the ability of simulating the structure and air permeability of multi constituent nonwoven layers.     

Radar‐based structural health monitoring of wind turbine blades: The case of damage localization

This short communication reports on a radar approach for structural health monitoring of wind turbine blades. Therefore, a bistatic frequency‐modulated continuous wave (FMCW) radar in the frequency range from 33.4 to 36.0 GHz has been developed and tested experimentally using a laboratory wind turbine demonstrator. A differential damage localization framework is presented here that exploits signal differences between measurements from the intact and the damaged structure for 3D imaging of the defect. We have achieved the localization of a 30‐mm cut in a glass fiber composite structure as well as the localization of a water pack at the backside of the specimen with a localization error of several centimeters.     

Optimal planning of distributed generation with application of multi-objective algorithm including economic,environmental and technical issues with considering uncertainties

This paper proposes a stochastic multi-objective model for integration of distributed generations (DGs) in distribution networks. The proposed model determines the optimal location and size of DGs by optimising different objective functions dependently and simultaneously subject to the operating constraints. If proper sizes of DGs are located in suitable sites and are also managed properly they can improve integrity, reliability and efficiency of the system. Regarding the widespread impact of uncertainties, some strategies must be devised in order to incorporate them well into power system modelling and hence achieve the best possible strategy to be adopted which its characteristics keep closer to reality. The most important uncertainties in network planning are load forecasting and market price errors. The proposed scheme is solved using non-dominated sorting genetic algorithms II, allowing the distribution company (DisCo) to exercise his/her personal preferences. To validate the effectiveness of the proposed scheme, simulations are carried out on a 33-bus distribution network and finally the attained results are discussed.     

Numerical Study of Three Different Approaches to Simulate Nanofluids Flow and Heat Transfer in a Microtube

In this paper, Eulerian, mixture and single phase models are used to simulate laminar and turbulent forced convective flow of SiO₂‐EG nanofluid in a microtube. The comparison between the three approaches and other formula shows that for laminar and turbulent flow the single phase model shows higher heat transfer enhancement and is more precise in comparison to the other Eulerian and mixture models.      

Success criteria analysis in support of probabilistic risk assessment for nuclear power plants: application on SGTR accident

Success criteria analysis (SCA) bridges the gap between deterministic and probabilistic approaches for risk assessment of complex systems.To develop a risk model,SCA evaluates systems behaviour in response to postulated accidents using deterministic approach to provide required information for the probabilistic model.A systematic framework is proposed in this article for extracting the front line systems success criteria.In this regard,available approaches are critically reviewed and technical challenges are discussed.Application of the proposed methodology is demonstrated on a typical Westinghouse-type nuclear power plant.Steam generator tube rupture is selected as the postulated accident.The methodology is comprehensive and general;therefore,it can be implemented on the other types of plants and complex systems.     

40 Gb/s 4-QAM OFDM radio over fiber system at 60 GHz employing coherent detection

In this paper, the simulation of 60 GHz millimeter-wave radio over fiber link with 4-QAM OFDM modulation format at 40 Gb/s over 150 km SMF is proposed. The 60 GHz millimeter-wave signal is generated by the optical heterodyne method. Coherent detection has been used at the receiver to down-convert millimeter-wave signal to IF band. Introduction of the OFDM modulation in RoF-based system realizes the benefits of higher order modulations (such as 4-QAM, 16-QAM, etc.) to ensure the good spectral efficiency and multi-gigabit access. The performance of the system is analyzed by Q-factor and BER by which it can be shown that the best results are obtained at the input power of 10 dBm. The simulation results clearly demonstrate the feasibility of this 4-QAM OFDM RoF system over 150 km fiber link.     

MIP-based heuristics for lotsizing in capacitated pure flow shop with sequence-dependent setups

Lotsizing in capacitated pure flow shop with sequence-dependent setups has been considered in this paper. An exact formulation of the problem is provided as a mixed-integer program. It is well known that the capacitated lotsizing and scheduling problem (CLSP) is NP-hard. The introduction of serially arranged machines and sequence-dependent setups makes the problem even more complicated. Five MIP-based heuristics based on iterative procedures are provided. The first three heuristics are based on the original model but to solve non-small instances of problem, the last two heuristics are based on permutation flow shop problem which ignores the majority of combinations. To test the accuracy of heuristics, two lower bounds are developed and compared against the optimal solution. The trade-offs between solution quality and computational times of heuristics are also provided.     

Estimation of the Maximum Annual Loads Modeling for Kingdom of Bahrain

The present paper proposes the impact of the air temperature on electricity demand as expected. It is clear that the annual maximum load is recorded versus the years starting by the year 2009 up to 2012. At present, the graph fitting technique is applied with some mathematical and computational tools based on the actual values of the years 2009 up to 2012 considering the lower values, the higher values and the average values of the annual maximum loads for Kingdom of Bahrain. For the three scenarios, the models are obtained by curve fitting technique. As well, the model of actual loads is obtained finally which has mostly the closest values obtained.     

Analytical solution for two-phase flow between two rotating cylinders filled with power law liquid and a micro layer of gas

This paper deals with the effects that a thin gas layer exerts on the hydrodynamic aspects of power law liquid in a radial Couette flow between two cylinders. Analytical solution is made to determine the velocity profile in the two-phase flow system occupied by the power law liquid and the micro layer of a gas. It is shown that the thin (micro) gas layer contributes in reducing torque to set the fluid in motion in most cases. However, by considering generalized power law liquids, this paper limits the credibility for the positive role of the gas layer on reducing the torque for lubrication. For instance, when n < 0.5 (n is the behavior index of the liquid), slight increment in the torque (about 6%) is reported. Finally, energy gradient method is used for stability analysis. It is shown that the stability nature may be changed based on behavior index of the liquid.