New results on PWARX model identification based on clustering approach

This paper deals with the problem of piecewise auto regressive systems with exogenous input(PWARX) model identification based on clustering solution. This problem involves both the estimation of the parameters of the affine sub-models and the hyper planes defining the partitions of the state-input regression. The existing identification methods present three main drawbacks which limit its effectiveness. First, most of them may converge to local minima in the case of poor initializations because they are based on the optimization using nonlinear criteria. Second, they use simple and ineffective techniques to remove outliers. Third, most of them assume that the number of sub-models is known a priori. To overcome these drawbacks, we suggest the use of the density-based spatial clustering of applications with noise(DBSCAN) algorithm. The results presented in this paper illustrate the performance of our methods in comparison with the existing approach. An application of the developed approach to an olive oil esterification reactor is also proposed in order to validate the simulation results.     

Airborne hyperspectral mapping of trees in an urban area

The management of trees in urban areas requires accurate maps, which are difficult to build in the dense patchwork of numerous material properties. Remote sensing is a useful technique that measures the response of all vegetation occurrences, including trees, when high spatial resolution is available. The continuous narrow spectral bands of hyperspectral images enable the detection of the oxygen and water content, which ensures a perfect correction of the atmospheric effect. When calibrated, sunlight reflectance images can be used to map surface chemical compositions by the detection of diagnostic and sharp absorption features. In the visible and near- infrared, the vegetation is detected by chlorophyll-a absorption features that are characteristic of the pigment content. The reflectance intensities due to the texture of leaves occur between 450 and 920 nm while the water content imprint is detectable beyond 920 nm. The sharp spectral feature intensities of the main associated pigments, not only chlorophylls, are well quantified by indices measuring a normalized difference of reflectance in a spectral interval between two bounding wavelengths. A regression line calculated on all bands within that interval ensures a low sensitivity of the indices to the smaller variations in reflectance intensity. Such unbiased indices may be combined, using successive index thresholds deduced from a training spectral library, to divide the spectra into subsets, minimizing the confusion between the numerous vegetation types with almost identical compositions. Therefore, for each subset of the spectra, a classic spectral angle mapping (SAM) method can be used on the corresponding sub-selection of the spectral library to measure angles at full spectral resolution and map tree types with great accuracy, grouped according to their spectral similarity. In this study, chemical and physical information is carefully separated. The tree crown physical properties are studied by comparing the local juxtaposition of pixel sets to a characteristic texture identifiable by image segmentation into objects. Instead of looking for objects in the reflectance image or any statistical compression of its information, a 25 channel co-image, built from 11 information layers of chemical sharp spectral feature indices and 14 information layers of SAM indices matching a spectral library of reference vegetation groups, was used. Tree canopies also present wide internal variations due to (i) a complex mixture with a background in the case of sparse foliage, or (ii) pigment content adaptation to light exposure intensity from one side to another. Both effects are minimized by using the mean spectrum of each object, assuming that less significant spectra, being at plus or minus one or two standard deviations from an object mean spectrum, would be less affected by anomalous pixel data. Thus, two overlapping hierarchic layers at the pixel scale and the object scale are available to describe the main chemistry or pigment content that identifies the vegetation types. The final classification is given by the upper layer at the object scale but in such an organization, the pixel scale layers can be used to analyse the data further and reorder them to obtain other parameters potentially useful for management purposes.     

Real-Time Detection of Terahertz Pulse Amplitude and Position

A novel and continuous detection scheme for the pulse amplitude and temporal position of a terahertz time domain system is presented. Currently, we have achieved a sampling time of 25 Hz and a resolution of less than 70 fs. The method is therefore very well suited for online measurements in production processes to monitor the thickness and inhomogeneities in the composition of non-conducting materials.     

Potential effects of ultrafiltration process and date powder on textural,sensory, bacterial viability,antioxidant properties and phenolic profile of dromedary Greek yogurt

The aim of this study was to improve textural and antioxidant capacity of dromedary yogurt using ultrafiltration process and date powder. Ultrafiltration increased total solids content of dromedary milk within the range considered optimal to develop yogurt. Texture profile of Greek yogurt fortified with date powder (GYD) improved considerably compared to control. Sample of GYD are more appealing to consumer than control. LC-ESI-MS analysis of GYD extracts allowed the identification of fifteen phenolic compounds, among which quinic acid and cirsiliol were found to be the major phenolic acid and flavonol, respectively. GYD exhibited the highest DPPH•-radical scavenging activity, Fe²⁺ chelating capacity and Fe³⁺ reducing power. The follow-up of physical and microbiological stability of GYD and control during cold storage showed that date powder significantly increased bacterial counts and decreased syneresis. Therefore, ultrafiltration and date powder could be valued as effective tool to solve the poor consistency of dromedary milk products.     

Photocatalytic degradation of methyl orange dye by NiFe<Subscript>2</Subscript>O<Subscript>4</Subscript> nanoparticles under visible irradiation: effect of varying the synthesis temperature

Nanoparticles of nickel ferrites (NiFe₂O₄) were synthesized at different temperature of synthesis (25, 50 and 80 °C) through the chemical co-precipitation method. The synthesized powders were characterized using X-ray diffraction for crystallite size and lattice parameter calculation. It reveals the presence of cubic spinel structure of ferrites with crystallite size between 29 and 41 nm. Transmission electron microscopy and scanning electron microscopy showed uniform distribution of ferrite particles with some agglomeration. The Fourier-transform infrared spectroscopy showed absorption bonds, which were assigned to the vibration of tetrahedral and octahedral complexes. Raman spectroscopy is used to verify that we have synthesized ferrite spinels and determines their phonon modes. The thermal decomposition of the NiFe₂O₄ was investigated by TGA/DTA. The optical study UV–visible is used to calculate the band gap energy. Magnetic measurements of the samples were carried out by means of vibrating sample magnetometer and these studies reveal that the formed nickel ferrite exhibits ferromagnetic behavior. Photoluminescence showed three bands of luminescence located at 420, 440 and 535 nm. The photocatalytic properties of nickel ferrite (NiFe₂O₄) nanoparticles were evaluated by studying the photodecomposition of methyl orange as organic pollutant models and showed a good photocatalytic activity.     

CRAN,H‐CRAN,and F‐RAN for 5G systems: Key capabilities and recent advances

The world of telecommunication is witnessing a swift metamorphosis towards fifth generation cellular networks. Particularly, the rapid shift from a user centric to a device centric communication has created a tremendous impact on service complexity and network requirements. The future networks present requisite needs in ubiquitous throughput, low latency, and high reliability. They are also envisioned to provide energy efficiency, spectrum reuse, network scalability, and robustness as well as improved quality of user experience, which proves to be of ultimate importance. Accordingly, government, academic, and industrial institutions are working together to fulfill these challenging goals. Their research efforts have been extensively reported in various topics and directions, such as heterogeneous small cell networks, millimeter wave communication, massive multiple input multiple output, network function virtualization, software‐defined network, and device‐to‐device communication. More interestingly, a revolutionary network architecture based on cloud computing and centralized processing is adopted as one of the best candidates for fifth generation. It is denoted Cloud Radio Access Network (CRAN) and (H‐CRAN) in heterogeneous networks. An upgraded version, namely, Fog RAN (F‐RAN), with caching and fog computing capabilities is also presented. Environmental friendly, it ensures flexibility and scalability with reduced expenditures. This paper presents the aforementioned key technological functionalities and surveys the benefits and challenges of CRAN, H‐CRAN, and F‐RAN.     

Antioxidant activities of enzymatic‐hydrolysed proteins of dromedary (Camelus dromedarius) colostrum

This work investigated the antioxidant activities of dromedary colostrum proteins before and after hydrolysis by pepsin, trypsin, α‐chymotrypsin, pancreatin and papain. The enzymatic hydrolysis affected the degrees of hydrolysis, electrophoretic profiles, molecular weight distribution and hydrophobic/hydrophilic properties of the generated peptides. The antioxidant activities were evaluated using four antioxidant assays, including 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS) radical‐scavenging activities, ferric reducing power and ferrous ion chelating activity. Interestingly, the antioxidant activities of dromedary colostrum proteins were enhanced after enzymatic hydrolysis. The highest antioxidant potential was obtained by pancreatic hydrolysates (P ≤ 0.05). These results suggest that dromedary colostrum protein hydrolysates are an important source of natural antioxidant peptides.