Modeling and characterization of microwave breakdown at atmospheric pressure in OMUX filters

For output multiplexer (OMUX) filters placed in telecommunication satellites, microwave breakdown happens in an involuntary and undesirable way during tests at atmospheric pressure. This avalanche phenomenon is due to exponential growth of the electronic density caused by thermoelectronic emission under strong electromagnetic field magnitude. In this paper, our objective is to model and characterize experimentally multipole OMUX filters composed with coupled cavities. For identifying the element responsible for the breakdown, the electric field is calculated within each cavity and each iris. In order to characterize the breakdown phenomenon, we proposed an experimental test bench and we measured the power, both at the input and at the output of the filter. The article details the theoretical breakdown prediction and the experimental setup for such a structure. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:46–54, 2014.     

Unsupervised learning of prototypes and attribute weights

In this paper, we introduce new algorithms that perform clustering and feature weighting simultaneously and in an unsupervised manner. The proposed algorithms are computationally and implementationally simple, and learn a different set of feature weights for each identified cluster. The cluster dependent feature weights offer two advantages. First, they guide the clustering process to partition the data set into more meaningful clusters. Second, they can be used in the subsequent steps of a learning system to improve its learning behavior. An extension of the algorithm to deal with an unknown number of clusters is also proposed. The extension is based on competitive agglomeration, whereby the number of clusters is over-specified, and adjacent clusters are allowed to compete for data points in a manner that causes clusters which lose in the competition to gradually become depleted and vanish. We illustrate the performance of the proposed approach by using it to segment color images, and to build a nearest prototype classifier.     

TOA Estimation Technique for IR‐UWB Based on Homogeneity Test

This paper deals with the estimation of the time of arrival (TOA) of ultra‐wideband signals under IEEE 802.15.4a channel models. The proposed approach is based on a randomness test and consists of determining whether an autoregressive (AR) process modeling an energy frame is random or not by using a distance to measure the randomness. The proposed method uses a threshold that is derived analytically according to a preset false alarm probability. To highlight the effectiveness of the developed approach, simulation setups as well as real data experiments are conducted to assess the performance of the new TOA estimation algorithm. Thereby, the proposed method is compared with the cell averaging constant false alarm rate technique, the threshold comparison algorithm, and the technique based on maximum energy selection with search back. The obtained results are promising, considering both simulations and collected real‐life data.     

Prediction‐based cluster management for target tracking in wireless sensor networks

The key impediments to a successful wireless sensor network (WSN) application are the energy and the longevity constraints of sensor nodes. Therefore, two signal processing oriented cluster management strategies, the proactive and the reactive cluster management, are proposed to efficiently deal with these constraints. The former strategy is designed for heterogeneous WSNs, where sensors are organized in a static clustering architecture. A non‐myopic cluster activation rule is realized to reduce the number of hand‐off operations between clusters, while maintaining desired estimation accuracy. The proactive strategy minimizes the hardware expenditure and the total energy consumption. On the other hand, the main concern of the reactive strategy is to maximize the network longevity of homogeneous WSNs. A Dijkstra‐like algorithm is proposed to dynamically form active cluster based on the relation between the predictive target distribution and the candidate sensors, considering both the energy efficiency and the data relevance. By evenly distributing the energy expenditure over the whole network, the objective of maximizing the network longevity is achieved. The simulations evaluate and compare the two proposed strategies in terms of tracking accuracy, energy consumption and execution time. Copyright © 2010 John Wiley & Sons, Ltd.     

Effect of the dietary supplementation of essential oils from rosemary and artemisia on muscle fatty acids and volatile compound profiles in Barbarine lambs

Eighteen Barbarine lambs (3 months of age), were assigned for 95 days to 3 treatments: six lambs were fed a barley-based concentrate plus oat hay ad libitum (control group, C); other lambs received the control diet plus essential oil (400 ppm DM) either of Rosmarinus officinalis (R400 group; n = 6) or of Artemisia herba alba (A400 group; n = 6). At slaughter the muscle longissimus dorsi was sampled and subjected to fatty acid and volatile organic compounds (VOC) analyses. The A400 lambs presented a greater amount of vaccenic, rumenic and linolenic acids and of polyunsaturated fatty acids (PUFA) in meat than the C and R400 animals. Essential oils supplementation did not affect meat VOC profile though the sesquiterpenes copaene and β-caryophyllene were detected only in the meat of R400 and A400 lambs. It is concluded that the supplementation of rosemary or artemisia essential oils does not produce detrimental effects on lamb meat VOC profile. The supplementation of artemisia can improve meat healthy properties.     

Deep learning and handcrafted features for one-class anomaly detection in UAV video

Multimedia Tools and Applications - Visual surveillance systems have recently captured the attention of the research community. Most of the proposed surveillance systems deal with stationary...     

基于流形特征的视频情感分析与识别

本文研究了基于Isomap的非线性降维方法,对由面部表情序列提取的面部动画参数特征进行降维,分析了降维后的流形特征空间与认知心理学情感空间之间的关系。实验结果表明,Isomap降维后的情感流形特征能够表现情感的强度变化,而且比PCA降维特征对情感强度的描述更加合理和平滑;情感识别实验也表明,使用Isomap降维流形特征的识别率要高于原始情感特征和PCA降维特征,而且对各种情感的识别结果更加均衡。     

Reverse Effect of Opuntia ficus‐indica L. Juice and Seeds Aqueous Extract on Gastric Emptying and Small‐Bowel Motility in Rat

This study was conducted to compare the effects of juice and seeds on gastric emptying, small‐bowel motility and intestinal ion transport. Separate groups of rats were randomized to receive NaCl, increasing doses of juice (5, 10, and 20 mL/kg, b.w.) or seeds aqueous extract (100, 200, and 400 mg/kg, b.w.). Simultaneously, two other groups were received, the reference drugs; clonidine (1 mg/kg) and yohimbine (2 mg/kg). The charcoal meal was used as a suspension for gastrointestinal motility test. The purgative action of juice was confirmed using the loperamide (5 mg/kg, p.o.) induced constipation. To evaluate the antisecretory effect, we were used as a hypersecretion agent, the castor oil at the dose of 5 mL/kg. Compared to the control and standard groups, we were showed that the prickly pear has an opposite effect on small‐bowel motility and gastric emptying. Indeed, the juice at various doses has a laxative effect of gastrointestinal transit in healthy and constipated‐rats. However, the aqueous extract of the seeds leads to a reduction of motility in normal rats which gives it a remarkable antidiarrhoeal activity, a notable intestinal fluid accumulation decline and electrolyte concentrations reestablishment. Moreover, orally juice administered at different doses accelerated the stomach emptying time in contrast to the seeds aqueous extract. More importantly, a significant variation in the phytochemical constituents levels between juice and seeds was found. These findings confirm the reverse therapeutic effects of this fruit in the treatment of digestive disturbances such as difficulty stool evacuation and massive intestinal secretion, likewise, the gastric emptying process perturbation.     

Nutritional constituents,phytochemical profiles, <Emphasis Type="Italic">in vitro</Emphasis> antioxidant and antimicrobial properties,and gas chromatography–mass spectrometry analysis of various solvent extracts from grape seeds (<Emphasis Type="Italic">Vitis vinifera</Emphasis> L.)

The present study revealed that the nutritive value of grape seeds (Vitis vinifera L.) was 383.55±0.13 Kcal/100 g, with magnesium as the most abundant mineral element (70.44±0.88 mg/L). The maximum phenolic (392.58±1.70mg of GAE/g), flavonoid (256.16±1.60 mg of QE/g), and tannin (30.95±0.17mg of CE/g) contents were also found in the ethanol, dichloromethane, and hexane extracts, respectively. The major phytochemical compounds in the ethyl acetate extract were identified via gas chromatography–mass spectrometry (GC–MS) analysis. The ethanol extract has the highest antioxidant activity (IC₅₀=140±1.20 μg/mL for DPPH, 145.28±0.45mg α-tocopherol/g for total antioxidant capacity, and EC₅₀=80±1.41 μg/mL for ferric-reducing power assays). For β-carotene test, the highest antioxidant activity was obtained in the hexane extract. A satisfactory antimicrobial activity was found against a panel of microorganisms with the ethyl acetate extract as the best antimicrobial agent. Additionally, it was found that the bactericidal concentration required for the grape seed extract to kill Listeria monocytogenes should be less than 12.50 mg/mL (minimum inhibitory concentration=4).