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Adaptive control of a class of nonlinear time-varying systems with multiple models

Control Theory and Technology 2016年第4期14卷 323-334页

作者： koshy george Karpagavalli SUBRAMANIAN PES Centre for Intelligent Systems Department of Telecommunication Engineering PES Institute of Technology Bangalore India PES Centre for Intelligent Systems Department of Electronics and Communication Engineering PES University Bangalore India

The adaptive control of nonlinear systems that are linear in the unknown but time-varying parameters are treated in this paper. Since satisfactory transient performance is an important factor, multiple models are required as these parameters change abruptly in the parameter space. In this paper we consider both the multiple models with switching and tuning methodology as well as multiple models with second level adaptation for this class of systems. We demonstrate that the latter approach is better than the former.

关键词： Nonlinear time-varying systems adaptive control multiple models

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Achieving higher strength in Cu–Ag–Zr alloy by warm/hot rolling

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Rare Metals 2017年第4期36卷 263-267页

作者： S. Chenna Krishna Abhay K. Jha Bhanu Pant koshy M. george Materials and Mechanical Entity Vikram Sarabhai Space Centre Trivandrum 695022 India

High-strength Cu-3Ag-0.5Zr alloy plates were produced by multi-pass rolling in the temperature range of 500-800 ℃. An increase in strength was observed by rolling in the aforementioned range without significant loss in ductility. All the rolled samples show higher strength than solution-treated and aged samples. The maximum strength was observed for plates rolled at 500 ℃ with a yield strength and ultimate tensile strength of 311 and 385 MPa, respectively, and retaining a ductility of 23 %. Transmission electron microscopy （TEM） studies showed uniform distribution of fine silver precipitates and high dislocation density in the rolled samples. Nevertheless, the size of precipitates and dislocation density varied with the rolling temperature. The superior strength achieved in the rolled samples is attributed to grain refinement, dislocation strengthening, and precipitation hardening. This method can be employed to produce high-strength plates of pre- cipitation hardenable copper alloys.

关键词： Warm/hot rolling Higher strength Copperalloy Strengthening

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Modulated orientation-sensitive terahertz spectroscopy

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Photonics Research 2016年第3期4卷 1-8页

作者： Rohit Singh Deepu koshy george Chejin Bae K.A.Niessen A.G.Markelz Department of Physics and Astronomy Depauw University Department of Physics Virginia Tech Department of Electrical Engineering University at Buffalo Department of Physics University at Buffalo

Intramolecular vibrations of large macromolecules reside in the terahertz range. In particular, protein vibrations are closely spaced in frequency, resulting in a nearly continuous vibrational density of states. This density of vibrations interferes with the identification of specific absorption lines and their subsequent association with specific functional motions. This challenge is compounded with the absorption being dominated by the solvent and local relaxational motions. A strategy for removing the isotropic relaxational loss and isolating specific vibrations is to use aligned samples and polarization-sensitive measurements. Here, we demonstrate a technique to rapidly attain the anisotropic resonant absorbance using terahertz time domain spectroscopy and a spinning sample. The technique, modulated orientation-sensitive terahertz spectroscopy(MOSTS), has a nonzero signal only for anisotropic samples, as demonstrated by a comparison between a silicon wafer and a wire grid polarizer. For sucrose and oxalic acid molecular crystals, the MOSTS response is in agreement with modeled results for the intermolecular vibrations. Further, we demonstrate that, even in the presence of a large relaxational background, MOSTS isolates underlying vibrational resonances.

关键词： THz Modulated orientation-sensitive terahertz spectroscopy

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A rare presentation of Guillain-Barre syndrome with GQ1b positivity:A case report

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Asian Pacific Journal of Tropical Medicine 2022年第7期15卷 332-334页

作者： Minu george Neena Baby Pradeep Mathew koshy Rajendran Ullatil Sureshkumar Radhakrishnan Department of Neurology Renai Medicity Multi Super Speciality HospitalKochiKeralaIndia Department of Nephrology Renai Medicity Multi Super Speciality HospitalKochiKeralaIndia Department of General Medicine Renai Medicity Multi Super Speciality HospitalKochiKeralaIndia

Rationale:To report a case of cervicobrachial variant of acute inflammatory demyelinating polyneuropathy presenting with papilledema and GQ1b *** concern:A 35-year-old female,68 days postpartum,presented with headache,vomiting,and gait difficulty in swallowing with bilateral upper limb weakness and difficulty in walking,13 days after ChAdOx1 nCoV-19 ***:Guillain-Barre syndrome with GQ1b ***:Five cycles of plasmapheresis were ***:The patient’s clinical condition *** weakness improved and she could walk without *** were mild sensory symptoms involving upper limbs which gradually ***:AIDP should be considered in case of weakness following ChAdOx1 nCoV-19 ***-cytological dissociation and anti-GQ1b positivity are needed to confirmed the diagnosis.

关键词： ChAdOx1nCoV-19 Papilledema Albuminocytological dissociation Guillain-Barre syndrome Acute inflammatory demyelinating polyneuropathy

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Journal of Semiconductors 2015年第12期36卷 24-29页

作者： Jiji koshy Soosen Samuel.M Anoop Chandran K.C.george Department of Physics S.B.College

The ac conduction mechanism in copper oxide nanoparticles with 8 nm size, synthesized by a precipitation method was studied by analyzing ac conductivity in the frequency range of 50 Hz-1 MHz and in the temperature range of 373-573 K. X-ray diffraction and transmission electron microscopy （TEM） were employed for the structural and morphological characterization of CuO nanoparticles. The experimental and theoretical in- vestigations suggested that the ac conduction mechanism in CuO nanoparticles can be successfully explained by a correlated barrier hopping model, which provided reasonable values for the maximum barrier height and characteristic relaxation time. It was also found that bipolaron hopping become prominent up to a particular temperature and beyond that single polaron hopping predominates. Physical parameters such as hopping distance and density of defect states were also calculated. Photoluminescence studies confirm the presence of a surface defect in CuO nanoparticles.

关键词： CuO nanoparticles correlated barrier hopping defect states photoluminescence spectrum single polaron hopping

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Role of endoscopic ultrasound guided fine needle aspiration/biopsy in the evaluation of intra-abdominal lymphadenopathy due to tuberculosis

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World Journal of Gastrointestinal Endoscopy 2021年第12期13卷 649-658页

作者： Harshavardhan Rao B Priya Nair S Krishna Priya Archana george Vallonthaiel Dipu T Sathyapalan Anoop K koshy Rama P Venu Department of Gastroenterology Amrita Institute of Medical SciencesKochi 682041KeralaIndia Department of Pathology Amrita Institute of Medical SciencesKochi 682041KeralaIndia Department of Internal Medicine Amrita Institute of Medical Sciences and Research CentreKochi 682041KeralaIndia

BACKGROUND Intra-abdominal lymphadenopathy due to tuberculosis(TB)poses a diagnostic challenge due to difficulty in tissue *** endoscopic ultrasound guided fine needle aspiration/biopsy(EUS-FNA/B)has shown promise in the evaluation of mediastinal lymph nodes,its role in the evaluation of intra-abdominal lymphadenopathy is not *** To assess the role of EUS-FNA/B in the evaluation of intra-abdominal lymphadenopathy due to *** This was a retrospective study where patients with intra-abdominal lymphadenopathy who underwent evaluation with EUS-FNA/B were *** was diagnosed if the patient had any one of the following:(1)Positive acid fast bacilli(AFB)stain/TB GeneXpert/TB-polymerase chain reaction/AFB culture of tissue sample;and(2)Positive Mantoux test and response to anti-tubercular ***-FNA reports,clinical reports and imaging characteristics of patients were recorded for a detailed analysis of patients with *** A total of 149 patients underwent an EUS-FNA/B from lymph nodes(mean age 51±17 years,M:F=1.2).Benign inflammatory reactive changes were seen in 45 patients(30.2%),while 54 patients(36.2%)showed granulomatous inflammation with/without *** these,51 patients(94.4%)were confirmed to have TB as per pre-defined *** with TB were more likely to have hypoechoic and matted nodes[40 patients(67.7%)].EUS-FNA/B was found to have a sensitivity and specificity of 86%and 93%respectively,with a diagnostic accuracy of 88%in the evaluation of intra-abdominal lymphadenopathy due to *** EUS-FNA/B has a high diagnostic yield with a good sensitivity and specificity in the evaluation of intra-abdominal lymphadenopathy due to ***,the validity of these findings in populations with low prevalence of TB needs further evaluation.

关键词： Endoscopic ultrasound Lymph nodes Tuberculosis Mesenteric Intraabdominal

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