1,283 research outputs found

    Secure Control and Operation of Energy Cyber-Physical Systems Through Intelligent Agents

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    The operation of the smart grid is expected to be heavily reliant on microprocessor-based control. Thus, there is a strong need for interoperability standards to address the heterogeneous nature of the data in the smart grid. In this research, we analyzed in detail the security threats of the Generic Object Oriented Substation Events (GOOSE) and Sampled Measured Values (SMV) protocol mappings of the IEC 61850 data modeling standard, which is the most widely industry-accepted standard for power system automation and control. We found that there is a strong need for security solutions that are capable of defending the grid against cyber-attacks, minimizing the damage in case a cyber-incident occurs, and restoring services within minimal time. To address these risks, we focused on correlating cyber security algorithms with physical characteristics of the power system by developing intelligent agents that use this knowledge as an important second line of defense in detecting malicious activity. This will complement the cyber security methods, including encryption and authentication. Firstly, we developed a physical-model-checking algorithm, which uses artificial neural networks to identify switching-related attacks on power systems based on load flow characteristics. Secondly, the feasibility of using neural network forecasters to detect spoofed sampled values was investigated. We showed that although such forecasters have high spoofed-data-detection accuracy, they are prone to the accumulation of forecasting error. In this research, we proposed an algorithm to detect the accumulation of the forecasting error based on lightweight statistical indicators. The effectiveness of the proposed algorithms was experimentally verified on the Smart Grid testbed at FIU. The test results showed that the proposed techniques have a minimal detection latency, in the range of microseconds. Also, in this research we developed a network-in-the-loop co-simulation platform that seamlessly integrates the components of the smart grid together, especially since they are governed by different regulations and owned by different entities. Power system simulation software, microcontrollers, and a real communication infrastructure were combined together to provide a cohesive smart grid platform. A data-centric communication scheme was selected to provide an interoperability layer between multi-vendor devices, software packages, and to bridge different protocols together

    Solid State NMR Spectroscopy a Valuable Technique for Structural Insights of Advanced Thin Film Materials: A Review

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    Solid-state NMR has proven to be a versatile technique for studying the chemical structure, 3D structure and dynamics of all sorts of chemical compounds. In nanotechnology and particularly in thin films, the study of chemical modification, molecular packing, end chain motion, distance determination and solvent-matrix interactions is essential for controlling the final product properties and applications. Despite its atomic-level research capabilities and recent technical advancements, solid-state NMR is still lacking behind other spectroscopic techniques in the field of thin films due to the underestimation of NMR capabilities, availability, great variety of nuclei and pulse sequences, lack of sensitivity for quadrupole nuclei and time-consuming experiments. This article will comprehensively and critically review the work done by solid-state NMR on different types of thin films and the most advanced NMR strategies, which are beyond conventional, and the hardware design used to overcome the technical issues in thin-film research

    Use of solid-state NMR spectroscopy for investigating polysaccharide-based hydrogels:A review

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    Hydrogels find application in many areas of technology and research due to their ability to combine responsiveness and robustness. A detailed understanding of their molecular structure and dynamics (which ultimately underpin their functional properties) is needed for their design to be optimized and these hydrogels to be exploited effectively. In this review, we shed light on the unique capabilities of solid-state NMR spectroscopy to reveal this information in molecular detail. We review recent literature on the advancements in solid-state NMR techniques in resolving the structure, degree of grafting, molecular organization, water-biopolymer interactions and internal dynamical behavior of hydrogels. Among various solid-state NMR techniques, 13C cross polarization (CP) magic angle spinning (MAS) NMR is examined for its ability to probe the hydrogel and its trapped solvent. Although widely applicable to many types of polymeric and supramolecular hydrogels, the current review focuses on polysaccharide-based hydrogels

    Feasibility of diffusion weighted MR imaging in differentiating recurrent laryngeal carcinoma from radionecrosis

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    AbstractPurposeTo assess the feasibility of apparent diffusion coefficient (ADC) generated from diffusion weighted magnetic resonance imaging as a non invasive technique to differentiate tumor recurrence from radionecrosis in patients with laryngeal carcinoma.Materials and methodsTwenty one patients suspected of tumor recurrence underwent MRI including diffusion weighted imaging (DWI) (b 0 and 1000). ADC maps were generated and ADC values were measured at the lesion sites and the normal laryngeal tissues, and were compared with the histopathological results.ResultsThe mean ADC of tumor recurrence {1.04±0.34×10−3mm2/s (SD)} was significantly lower (p<0.0001) than the mean ADC of the normal laryngeal tissues in the same patient (1.48±0.099×10−3mm2/s) while the mean ADC of radionecrosis (1.79±0.41×10−3mm2/s) was significantly higher (p<0.04) than the mean ADC of the normal laryngeal tissues (1.49±0.095×10−3mm2). The mean ADC of tumor recurrence is significantly lower (p<0.0001) than the mean ADC of radionecrosis with 1.16×10−3mm2/s is the best cut value for differentiating tumor recurrence from radionecrosis.ConclusionADC can differentiate tumor recurrence from radionecrosis in laryngeal carcinoma

    Physical-model-checking to detect switching-related attacks in power systems

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    Recent public disclosures on attacks targeting the power industry showed that savvy attackers are now capable of occulting themselves from conventional rule-based network intrusion detection systems (IDS), bringing about serious threats. In order to leverage the work of rule-based IDS, this paper presents an artificially intelligent physical-model-checking intrusion detection framework capable of detecting tampered-with control commands from control centers of power grids. Unlike the work presented in the literature, the work in this paper utilizes artificial intelligence (AI) to learn the load flow characteristics of the power system and benefits from the fast responses of the AI to decode and understand contents of network packets. The output of the AI is processed through an expert system to verify that incoming control commands do not violate the physical system operational constraints and do not put the power system in an insecure state. The proposed content-aware IDS is tested in simulation on a 14-bus IEEE benchmark system. Experimental verification on a small power system, with an IEC 61850 network architecture is also carried out. The results showed the accuracy of the proposed framework in successfully detecting malicious and/or erroneous control commands

    Occurrence Et Evaluation Du Risque De L’histamine Dans Les Produits De La Peche Commercialises Sur Le Marche Marocain

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    The histamine levels of preserved and semi-preserved fish marketed in Morocco from 2013 to 2015 have been determined. This study presents the results of histamine control plan of 446 samples of fishery products collected from different areas of Morocco: retail markets, supermarkets, commercial and social restaurants. The synthesis of the data revealed that the occurrence of histamine is low with a non-compliance rate of 3.14 %. This rate is 2.02 % for canned sardines and 1.12 % for semi-preserved anchovies. The average histamine values of all batches analyzed did not exceed 5.63mg/100g. Average values were 5.14 mg/100 g for canned sardine and 7.76 mg/100 g for semi-preserved anchovies. These levels are much lower than the regulatory safety limit. Two qualitative risk assessments of histamine were carried out, one according to the marketing region and the other with reference to the places of marketing. The results showed that the area with the lowest risk is the northern coastal zone with an average of 2.11 mg/100 g and a non-compliance rate of 0.22%. Low-risk marketing places are the social type restaurants with an average of 4.14 mg/100g and a noncompliance rate of 0.22%. A ranking of various cities in Morocco was carried out according to histamine content of the marketed fishery products. The results demonstrate the relevance of the official control plan established by the competent Moroccan authority and the control measures implemented by the professionals. It can therefore be concluded that preserved and semipreserved fish marketed in Morocco are safe as related to the risk of histamine

    Effect of Fe Deficiency on Antioxidant System in Leaves of Three Flax Cultivars

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    The potential role of antioxidant enzymes as well as antioxidant compounds in protecting plant from the deleterious effect of iron deficiency was examined in different flax Linum usitassimum L. cultivars. Three flax cultivars (Sakha 1, Sakha 2 and Giza 8) were grown in water culture with (Fe-sufficient plants, +Fe) or without (Fe-deficient plants,-Fe) iron supply for 40 days. The obtained results showed that, iron deficiency severely decreased dry weight and concentration of iron in all cultivars leaf tissue. Besides this, to verify whether iron deficiency could induce alteration in reactive oxygen species, high concentration of lipid peroxidation (TBARS) and H2O2 content in leaves of flax cultivars were detected under (-Fe) compared to (+Fe) treatments. Iron deficiency can also modulate the content of glutathione (GSH) level, which were significantly increased in Fe deficient treatment compared to Fe-sufficient treatment among cultivars. Activity of superoxide dismutase (SOD) was increased under deficient treatment. In contrast, significant differences were observed between cultivars in the activity of Fe containing enzymes such as ascorbate peroxidase (APX), peroxidase (POD) and catalase (CAT) that was greater under Fe sufficient treatment, suggesting higher amounts of physiological iron in leaf tissue of all cultivars. In addition, some changes in POD isoenzyme profile was detected under iron stress.These results suggested that, these antioxidant compounds are the key compounds to protect cell from oxidative injury
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