An optimization model for a mechanical vapor compression desalination plant driven by a wind/PV hybrid system

A renewable hybrid system to produce domestic water is presented. It consists of a photovoltaic module, a wind turbine, a mechanical vapor compression desalination plant and a storage unit. An optimization model based on a mathematical programming is developed to control the energy flows exchanged among the system components in order to satisfy the domestic water demand. The model has been solved for three specific case studies in Morocco, where two of them are located in Rabat which aim to satisfy the hourly and monthly water demand of 20 households, whereas, the last one is in Essaouira, which aims to ensure the monthly water demand of 40 households. The main motivations behind selecting these specific case studies are the evaluation of the efficiency and feasibility of such system in two coastal sites having different characteristics of renewable energy sources. The obtained results show that the domestic water demands are satisfied in each time interval at a reasonable economic cost comparable to the current average cost of water in Morocco which is about 0.7 € m⁻³.     

Structural,Elastic, Electronic,and Magnetic Properties of the Full-Heusler Compounds Ti<Subscript>2</Subscript>Ni<Emphasis Type="Italic">X</Emphasis> (<Emphasis Type="Italic">X</Emphasis>= Al,Ga, and In)

We present a quantum-mechanical first-principle calculation of the structural, elastic, electronic, and magnetic properties of the full-Heusler compounds Ti₂NiX (X= Al, Ga, and In). The calculation uses the full-potential linearized augmented plane waves plus local orbital method to describe Ti₂-based Heusler alloys. The results show that these compounds exhibit half metallic characteristics over a wide range of mesh parameters and obey the Slater–Pauling rule, which states that the total magnetic moment per unit cell M _t = Z _t? 18 for half-Heusler compounds XYZ and M _t = Z _t? 24 for full-Heusler X ₂ YZ compounds. For these new alloys Ti₂NiX (X= Al, Ga, and In), we initially considered the two possible L2₁ structures AlCu₂Mn and CuHg₂Ti. However, two subsequent structural studies showed that only the CuHg₂Ti-like structure is half metallic. Over a wide range of mesh parameters, the calculations give a total magnetic moment of 3.00 μ _B. These results suggest that Ti₂NiX (X= Al, Ga, and In) are promising materials for spintronic applications.     

New spectral indicator assessing the efficiency of crop nitrogen treatment in corn and wheat

To reduce environment pollution from cropping activities, a reliable indicator of crop N status is needed for site-specific N management in agricultural fields. Nitrogen Nutrition Index (NNI) can be a valuable candidate, but its measurement relies on tedious sampling and laboratory analysis. This study proposes a new spectral index to estimate plant nitrogen (N) concentration, which is a critical component of NNI calculation. Hyperspectral reflectance data, covering bands from 325 to 1075 nm, were collected using a ground-based spectroradiometer on corn and wheat crops at different growth stages from 2005 to 2008. Data from 2006 to 2008 was used for new index development and the comparison of the new index with some existing indices. Data from 2005 was used to validate the best index for predicting plant N concentration. Additionally, a hyperspectral image of corn field in 2005 was acquired using an airborne Compact Airborne Spectrographic Imager (CASI), and the corresponding plant N concentration was obtained by conventional laboratory methods on selected area. These data were also used for validation. A new N index, named Double-peak Canopy Nitrogen Index (DCNI), was developed and compared to the existing indices that were used for N detection. In this study, DCNI was the best spectral index for predicting plant N concentration, with R² values of 0.72 for corn, 0.44 for wheat, and 0.64 for both species combined, respectively. The validation using an independent ground-based spectral database of corn acquired in 2005, yielded an R² value of 0.62 and a root-mean-square-error (RMSE) of 2.7 mg N g^− 1 d.m. The validation using the CASI spectral information, DCNI calculation was related to actual corn N concentration with a R² value of 0.51 and a RMSE value of 3.1 mg N g^− 1 d.m. It is concluded that DCNI, in association with indices related to biomass, has a good potential for remote assessment of NNI.     

An observation algorithm for nonlinear systems with unknown inputs

This paper deals with the design of unknown input observers for nonlinear systems. An algorithm which determines if the state and the unknown input of the system can be recovered in finite time is introduced. This algorithm leads to the transformation of the system into an extended block triangular observable form suitable for the design of finite time observers. The proposed method is useful to relax some restrictive conditions of the existing nonlinear unknown input observer design procedures.     

Discriminative speaker recognition using large margin GMM

Most state-of-the-art speaker recognition systems are based on discriminative learning approaches. On the other hand, generative Gaussian mixture models (GMM) have been widely used in speaker recognition during the last decades. In an earlier work, we proposed an algorithm for discriminative training of GMM with diagonal covariances under a large margin criterion. In this paper, we propose an improvement of this algorithm, which has the major advantage of being computationally highly efficient, thus well suited to handle large-scale databases. We also develop a new strategy to detect and handle the outliers that occur in the training data. To evaluate the performances of our new algorithm, we carry out full NIST speaker identification and verification tasks using NIST-SRE’2006 data, in a Symmetrical Factor Analysis compensation scheme. The results show that our system significantly outperforms the traditional discriminative support vector machines (SVM)-based system of SVM-GMM supervectors, in the two speaker recognition tasks.     

New deep-freezing process using renewable low-grade heat: From the conceptual design to experimental results

An exergy-based analysis applied to ideal thermochemical dipoles allowed to design an original process that could use low-grade energy, produced from a thermal solar collector at around 70 °C, to provide low-temperature cold, below −23 °C, in order to store deep-frozen food. The ideal coefficient of performance (COP) of this system is 0.5 and the exergetic yield is 1. Taking into account the process enthalpies and the sensible heat of the reactants, the COP_thermo is 0.17. The process functioning is described in this paper. It alternates between a regeneration mode during daytime and cold production mode during night-time. An experimental prototype was designed and built. It proved the feasibility of the concept and showed an experimental COP of about 0.06, which is similar to the up-to-date solar cooling systems, but at higher cold temperatures. The mean annual exergetic yield of the process is about 0.06.     

Internal energy flow analysis within a single effect sorption heat pump

The knowledge of the characteristics of unused, excess and untapped exergy allows a thorough analysis of internal energy flows distribution within a sorption heat pump. It can be applied to any system based on gas–liquid absorption, adsorption or solid–gas reaction as well as to any process based on the internal recycling of the energy flux. It can also be applied for the case of a simple effect ideal machine, in particular in the definition of processes where the COP is larger than 2: the levels at which the initial exergy is downgraded on the one hand, as well as, the upgraded excess exergy produced on the other allows the designer to make a judicious choice of a system.     

Anodic oxidation of bis(organylchalcogeno)acetylenes

The electrochemical oxidation of bis(organylchalcogeno)acetylenes has been examined in organic solvents. With symmetrical ones, R---Z---CC---Z---R (1) (Z=S, Se), and with unsymmetrical ones, R¹---S---CC---Z---R² (2) (Z=Se), in macroscale electrolyses the α-diesters R¹---Z(S)---CO---CO---Z---R² were obtained as the main products. If Z=Te, from 1 and 2, reactions were more complex and the cleavage of the C---Te bond was always observed.     

The relevance of global energy governance for Arab countries: The case of Morocco

Global climate and energy governance have led to the creation of a wide range of international and regional institutions, initiatives and financial mechanisms dedicated to fostering renewable energies. Furthermore, a low-carbon economy has evolved in recent years. The objective of this paper is to assess the potential benefits and merits of these institutions, initiatives and mechanisms from the perspective of the Middle East and North Africa (MENA) region. The central questions are if and how these organizations, initiatives and finance mechanisms could support a country from MENA in its efforts to implement large-scale capacities for renewable energy production. For this purpose, Morocco was chosen as a case study. The findings in this paper indicate that the existing institutions and financial mechanisms do not sum up to a coordinated governance approach, although the main needs of a country or region appear to be addressed. The existing institutions and financial mechanisms vary significantly in their ability to support countries, especially those taking the lead in renewable energy implementation.