Adaptive control of bi-directionally coupled Lorenz systems with uncertainties     

Jim Braselton  Adel El Shahat 《Journal of The Franklin Institute》2019,356(3):1287-1301

The bi-directionally coupled Lorenz systems are linked to the modeling of a coupled double loop thermosyphon system where the mass momentum and heat exchange are both considered. As the key parameters of the system, known as Rayleigh numbers, increase, the system of differential equations predicts typical flow dynamics in a thermosyphon from heat conduction to time-dependent chaos. In many applications including the thermosyphon systems, there are uncertainties associated with mathematical models such as unmodeled dynamics and parameter variations. Also, under the high heat environment for a thermosyphon, there exist external disturbances quantitatively linked to the Rayleigh numbers. All these sources constitute uncertainties to the dynamical system. Our objective is to design adaptive controllers to stabilize the chaotic flow in each thermosyphon loop with unknown system parameters and existence of uncertainties. The controllers consist of a proportional controller with an adaptive gain and a wavelet network that reconstructs the unknown functions representing the uncertainties. Explicit stability bounds and adaptive laws for the control parameters are obtained so that the coupled Lorenz systems are globally stabilized.  相似文献   

A new approach for constrained chaos synchronization with application to secure data communication     

Mohamed F. Hassan  Mohammad Hammuda 《Journal of The Franklin Institute》2019,356(12):6697-6723

In this paper, a new technique is introduced for chaos secure data communication. In this approach, in addition to the usually used techniques for data encryption, the concept of carrier encryption is introduced to increase the security level of the secure communication scheme. To fulfill this objective, at the transmitting end, two chaotic oscillators are coupled, and a set of inequality time dependent constraints with time dependent bounds is imposed on the generated chaotic signals. Moreover, to increase system complexity and its security level, the imposed set of constraints and their bounds are allowed to be changeable from one time period to another during the transmission process. As a result, the patterns of the generated chaotic signals are completely changed and the chaotic oscillator is completely encrypted. At the receiving end, the newly developed Constrained Smoothed Regularized Least Square (CSRLS) observer is used to synchronize the received constrained chaotic signals and hence retrieve the transmitted data. Using such an approach, the quality of the received information, measured by the Bit Error Rate (BER), is highly improved due to the superior performance of the developed CSRLS observer. The stability of the observer is analyzed, and simulation results are presented to show the efficiency and effectiveness of the proposed secure communication scheme.  相似文献   

Phonemic—Morphemic dissociation in university students with dyslexia: an index of reading compensation?     

Eddy Cavalli  Lynne G. Duncan  Carsten Elbro  Abdessadek El Ahmadi  Pascale Colé 《Annals of dyslexia》2017,67(1):63-84

A phonological deficit constitutes a primary cause of developmental dyslexia, which persists into adulthood and can explain some aspects of their reading impairment. Nevertheless, some dyslexic adults successfully manage to study at university level, although very little is currently known about how they achieve this. The present study investigated at both the individual and group levels, whether the development of another oral language skill, namely, morphological knowledge, can be preserved and dissociated from the development of phonological knowledge. Reading, phonological, and morphological abilities were measured in 20 dyslexic and 20 non-dyslexic university students. The results confirmed the persistence of deficits in phonological but not morphological abilities, thereby revealing a dissociation in the development of these two skills. Moreover, the magnitude of the dissociation correlated with reading level. The outcome supports the claim that university students with dyslexia may compensate for phonological weaknesses by drawing on morphological knowledge in reading.  相似文献   

Observer based (Q,V,R)-α-dissipative control for TS fuzzy descriptor systems with time delay     

H. Gassara  A. El Hajjaji  M. Kchaou  M. Chaabane 《Journal of The Franklin Institute》2014

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Alleviation of Dimethylnitrosamine-Induced Liver Injury and Fibrosis by Supplementation of Anabasis articulata Extract in Rats     

Azza M. Mohamed  Mohga S. Abdalla  Maha Z. Rizk  El-Sayed M. E. Mahdy  Abdel-Razik H. Farrag  Fatma S. El-Sharabasy  Hanan F. Aly  Mohamed R. Mohamed 《Indian journal of clinical biochemistry : IJCB》2014,29(4):418-429

Anabasis articulata (Forssk) Moq. (Chenopodiaceae) is an herb, grows in Egypt, and used in folk medicine to treat diabetes, fever, and kidney infections. The protective and therapeutic effects of the ethanol extract of A. articulata aerial parts were evaluated against dimethylnitrosamine (DMN)-induced liver fibrosis, compared with the standard drug, silymarin. Hepatic hydroxyproline content, serum transforming growth factor-β1 (TGF-β1), interleukin 10 (IL-10) and fructosamine were measured as liver fibrosis markers. Hepatic malondialdehyde (MDA), nitric oxide (NO), catalase (CAT), glutathione reductase (GR) and glutathione content (GSH) were measured as oxidant/antioxidant markers. Parallel histopathological investigations were also performed. Protective and therapeutic administration of A. articulata (100 mg/kg daily for 4 weeks), markedly prevented DMN-induced loss in body and liver weights. The extract significantly inhibited the elevation of hepatic hydroxyproline, NO and MDA (P < 0.05), as well as serum fructosamine, and TGF-β1 (P < 0.05) induced by DMN while it restored IL-10 to normal level in both protective and therapeutic groups. Furthermore, A. articulata prevented the depletion in CAT, GR, and GSH levels (P ≤ 0.05). In addition, oral administration of A. articulata extract and silymarin to both protective and therapeutic groups reduced the increase in liver function enzyme activities; alanine and aspartate amintransferases, gamma-glutamyl transferase in addition to alkaline phosphatase, and caused significant increase in serum albumin concentration as compared to DMN group. These data corresponded closely with those obtained for the drug silymarin. Histopathological studies confirmed the biochemical data and revealed remarkable improvement in liver architecture. Thus, it could be concluded that, A. articulata extract exhibited in vivo hepatoprotective and therapeutic effects against DMN-induced liver injury and may act as a useful agent in controlling the progression of hepatic fibrosis through reduction of oxidative stress and improving liver function.  相似文献   

Predicting e-readiness at firm-level: An analysis of technological,organizational and environmental (TOE) effects on e-maintenance readiness in manufacturing firms     

Mohamed Gamal Aboelmaged 《International Journal of Information Management》2014

This study predicts the impact of technological, organizational and environmental (TOE) determinants on e-maintenance technology readiness in manufacturing firms. Survey responses of 308 managers from a wide spectrum of manufacturing firms have been validated and analyzed by means of structural equation modelling. The findings indicate that dimensions of e-maintenance technology readiness in manufacturing firms are mainly influenced by technological and organizational determinants involving technological infrastructure and competence, expected benefits and challenges of e-maintenance, and firm size and ownership. Surprisingly, there is no significant effect of competitive pressures on e-maintenance readiness. This study offers managers and vendors a frame of reference to analyze firm's situation before initiating new innovations. In case of e-maintenance technology, adoption strategies should be built around fostering level of employees’ technological knowledge and skills, technology infrastructure as well as sustaining potential benefits and encountering potential challenges associated with e-maintenance technology. This paper is one of the early studies that predict dimensions of technology readiness index (TRI) through the determinants of technology–organization–environment (TOE) framework. Also, it is among the first attempts to link prominent technology adoption models to e-maintenance technology as a novel form of enterprise innovations.  相似文献   

A Quick,Accurate, and Free-of-Cost Inventory and Shelf-Reading Solution     

Maroun El Rayess 《Journal Of Access Services》2015,12(3-4):104-117

This article presents a solution that was used at Notre Dame University–Louaize (NDU) Library, Lebanon, to conduct efficient, accurate, and low-cost inventory and shelf reading. By exporting catalog records into an Excel spreadsheet and using nested formulas to compare records exported from the online library system against the books existing on the shelves, the inventory was successfully completed in a manageable time period. This simple solution, using a laptop and a handheld bar code reader, significantly reduced the number of staff and the amount of time required to perform the inventory. It also greatly reduced human error and inconsistencies faced in previously conducted inventories while helping to maintain staff concentration and enthusiasm for the project.  相似文献   

Neural ranking models for document retrieval     

Trabelsi  Mohamed  Chen  Zhiyu  Davison  Brian D.  Heflin  Jeff 《Information Retrieval》2021,24(6):400-444

Information Retrieval Journal - Ranking models are the main components of information retrieval systems. Several approaches to ranking are based on traditional machine learning algorithms using a...  相似文献   

Linking ethnic/racial discrimination to adolescent mental health: Sleep disturbances as an explanatory pathway     

Tiffany Yip  Mingjun Xie  Heining Cham  Mona El Sheikh 《Child development》2022,93(4):973-994

Ethnic/racial discrimination is associated with negative psychosocial outcomes, and this study considered sleep disturbance as a mediating pathway. Employing a combination of daily diary and biannual surveys, multilevel structural equation models estimated the indirect effects of sleep/wake concerns on negative, anxious, and positive mood, rumination, and somatic symptoms. In a sample of 350 urban Asian (74% Chinese, 8% Korean, 4% Indian, 1% Filipinx, 1% Vietnamese, and 12% other), Black, and Latinx (25% Dominican, 24% South American, 22% Mexican, 15% Puerto Rican, 5% Central American, and 9% other) youth (M = 14.27 years, 69% female, 77% U.S. born, 76% monoethnic/racial, data collected from 2015 to 2018), there was evidence for sleep disturbances mediating the impact of ethnic/racial discrimination on adjustment. Nighttime disturbance, daytime dysfunction, and daytime sleepiness evidenced partial or full mediation for daily- and person-level outcomes (υ = 0.1%–17.9%). Reciprocal associations between sleep disturbances and negative mood and rumination were also observed.  相似文献   

Correction to: Examining Agency in Children’s Nonfiction Picture Books     

Vaughn  Margaret  Sotirovska  Vera  Darragh  Janine J.  Elhess  Mohamed 《Children‘s Literature in Education》2022,53(2):291-291

Children's Literature in Education - In the original publication of the article unfortunately contained a mistake in the name of co-author Vera Sotirvoska.The correct name should be Vera...  相似文献