A systematic approach for COVID-19 predictions and parameter estimation.

The world is currently facing a pandemic called COVID-19 which has drastically changed our human lifestyle, affecting it badly. The lifestyle and the thought processes of every individual have changed with the current situation. This situation was unpredictable, and it contains a lot of uncertainties. In this paper, the authors have attempted to predict and analyze the disease along with its related issues to determine the maximum number of infected people, the speed of spread, and most importantly, its evaluation using a model-based parameter estimation method. In this research the Susceptible-Infectious-Recovered model with different conditions has been used for the analysis of COVID-19. The effects of lockdown, the light switch method, and parameter variations like contact ratio and reproduction number are also analyzed. The authors have attempted to study and predict the lockdown effect, particularly in India in terms of infected and recovered numbers, which show substantial improvement. A disease-free endemic stability analysis using Lyapunov and LaSalle's method is presented, and novel methods such as the convalescent plasma method and the Who Acquires Infection From Whom method are also discussed, as they are considered to be useful in flattening the curve of COVID-19.

Transition metal-catalyzed double Cvinyl-H bond activation: synthesis of conjugated dienes.

Conjugated dienes have occupied a pivotal position in the field of synthetic organic chemistry and medicinal chemistry. They act as important synthons for the synthesis of various biologically important molecules and therefore, gain tremendous attention worldwide. A wide range of synthetic routes to access these versatile molecules have been developed in the past decades. Transition metal-catalyzed cross-dehydrogenative coupling (CDC) has emerged as one of the utmost front-line research areas in current synthetic organic chemistry due to its high atom economy, efficiency, and viability. In this review, an up-to-date summary including scope, limitations, mechanistic studies, stereoselectivities, and synthetic applications of transition metal-catalyzed double Cvinyl-H bond activation for the synthesis of conjugated dienes has been reported since 2013. The literature reports mentioned in this review have been classified into three different categories, i.e. (a) Cvinyl-Cvinyl bond formation via oxidative homo-coupling of terminal alkenes; (b) Cvinyl-Cvinyl bond formation via non-directed oxidative cross-coupling of linear/cyclic alkenes and terminal/internal alkenes, and (c) Cvinyl-Cvinyl bond formation via oxidative cross-coupling of directing group bearing alkenes and terminal/internal alkenes. Overall, this review aims to provide a concise overview of the current status of the considerable development in this field and is expected to stimulate further innovation and research in the future.

Correlation of PD-L1 expression with toxicities and response in oropharyngeal cancers treated with definitive chemoradiotherapy.

Introduction: The programmed death receptor ligand 1 (PD-L1) is a cell-surface glycoprotein expressed in tumour cells (TCs) and is also upregulated in tumour infiltrating lymphocytes. The effect of PD-L1 expression on TCs and tumour-infiltrating lymphocytes (TILs) on acute radiation toxicity and response in oropharyngeal squamous cell carcinoma treated with concurrent chemoradiotherapy is less known. Material and methods: Squamous cell carcinoma of oropharynx with stage II-IVA (AJCC 8th) were recruited in this prospective observational study. Definitive radiation therapy (RT) of 70 Gray in 35 fractions at 2 Gray per fraction, 5 fractions a week in 2 phases was delivered with concurrent chemotherapy (cisplatin 40 mg/m2 weekly). Patients were assessed weekly for acute toxicities with Radiation Therapy Oncology Group criteria. Response assessment was done at 3 months post RT according to World Health Organization response assessment criteria. The programmed death receptor ligand 1 expression in TCs and TILs was correlated with acute toxicity and survival. Results: Of 51 patients, 20 (39.2%) had PD-L1 expression in TCs and 18 (35.3%) in TILs. Patients with PD-L1 expression in TCs had fewer grade ≥ 3 oral mucositis (25% vs. 58%; p = 0.02) and grade ≥ 3 dysphagia (25% vs. 55%; p = 0.046). The programmed death receptor ligand 1-tumour infiltrating lymphocytes positives had lower ≥ 3 grade oral mucositis (22% vs. 58%; p = 0.02) and ≥ 3 grade dysphagia (17% vs. 58%; p = 0.007). Two-year overall and progression-free survival rate for the PD-L1-tumour-positive vs. PD-L1-tumour-negative group was not different (p > 0.5). Conclusions: Positive PD-L1 expression is associated with fewer acute radiation toxicities, and this could be used as a potential biomarker.

Biocatalytic Synthesis of Novel Partial Esters of a Bioactive Dihydroxy 4-Methylcoumarin by Rhizopus oryzae Lipase (ROL).

Highly regioselective acylation has been observed in 7,8-dihydroxy-4-methylcoumarin (DHMC) by the lipase from Rhizopus oryzae suspended in tetrahydrofuran (THF) at 45 °C using six different acid anhydrides as acylating agents. The acylation occurred regioselectively at one of the two hydroxy groups of the coumarin moiety resulting in the formation of 8-acyloxy-7-hydroxy-4-methylcoumarins, which are important bioactive molecules for studying biotansformations in animals, and are otherwise very difficult to obtain by only chemical steps. Six monoacylated, monohydroxy 4-methylcoumarins have been biocatalytically synthesised and identified on the basis of their spectral data and X-ray crystal analysis.

Regioselective Metal-Free Decarboxylative Multicomponent Coupling of α-Amino Acids, Aldehydes and Isonitriles Leading to N-Substituted Azacyclic-2-carboxamides with Antithrombotic Activity.

An atom-economical regioselective synthesis of N-substituted prolinamides or N-substituted piperidine-2-carboxamides via a metal-free decarboxylative multicomponent coupling between l-proline or pipecolic acid, aldehydes, and isonitriles is described. The cascade event involves sequential imine formation, decarboxylation, isonitrile insertion, and hydrolysis to afford the product in one-pot. Two of the prolinamides were found to display appreciable antithrombotic activity via inhibition of platelet aggregation.

Utility of a multiplex pathogen detection system directly from respiratory specimens for treatment and diagnostic stewardship.

The availability of syndrome-based panels for various ailments has widened the scope of diagnostics in many clinical settings. These panels can detect a multitude of pathogens responsible for a particular condition, which can lead to a timely diagnosis and better treatment outcomes. In contrast to traditional identification methods based on pathogen growth on culture, syndrome-based panels offer a quicker diagnosis, which can be especially beneficial in situations requiring urgent care, such as intensive care units. One such panel is the Biofire Filmarray Pneumonia plus Panel (BFP), which we have compared against microbiological culture and identification. The lower respiratory samples from patients were tested with BFP, culture, and identification with culture considered the gold standard. The phenotypic antibiotic susceptibility results (Vitek 2) were compared with the antimicrobial resistance (AMR) genes detected in BFP. Statistical analysis was carried out using GraphPad 7.0 and MS Excel (Microsoft Inc.). The results showed a positive percent agreement of 100% and a negative percent agreement of 47.8% with an overall agreement of 76.72% compared to culture. BFP was better at identifying fastidious bacteria, and the agreement with culture was higher for high bacterial identification numbers (107 and 106). There was also a correlation between the number of pathogens detected and growth in culture. Carbapenemase genes were detected in around 80% of phenotypically resistant samples and correlated with in-house PCR 60% of the time. Hence, BFP results need to be interpreted with caution especially when multiple pathogens are detected. Similarly, the presence or absence of AMR genes should be used to guide the therapy while being watchful of unusual resistance or susceptibility. The cost constraints and low throughput call for patient selection criteria and prioritization in emergency or resource-limited conditions.IMPORTANCEApplication of syndrome-based panels in clinical microbiology is of huge support in infectious conditions requiring urgent interventions, such as pneumonia. Interpreting the results requires caution; hence, we have compared the results obtained from Biofire Filmarray Pneumonia plus Panel with standard microbiological methods.

Kodamaea ohmeri: A rare yeast causing invasive infections in immunocompromised patients.

INTRODUCTION: Kodamaea ohmeri is a rare, recognized pathogen that has previously been isolated from environmental sources. The patients commonly affected by this yeast include immunocompromised as well as immunocompetent patients having several associated risk factors. METHODOLOGY: We report three cases in which K. ohmeri was isolated from blood using Bact T/ALERT. Identification was carried out by MALDI-TOF MS (Vitek-MS, BioMérieux, Marcy-l'Etoile, France) in addition to color characteristics on chromogenic media. The patients had diminished immune response on account of a multitude of comorbidities. RESULTS: K. ohmeri can be misidentified as Candida tropicalis, Candida albicans, or Candida hemolounii by conventional methods; correct and timely identification can be achieved by MALDI-TOF MS. Antifungal susceptibility breakpoints for K. ohmeri are currently not defined. An Echinocandin was added to the treatment regimen of all three of the cases. CONCLUSIONS: Identification of K. ohmeri using conventional methods is difficult and unusual yeasts should be carefully observed, especially upon prolonged incubation.

Identification of Candida auris by PCR and assessment of biofilm formation by crystal violet assay.

INTRODUCTION: Candida auris is a notorious pathogen capable of forming biofilms on devices as well as host tissues, often culminating in infections. We evaluated characteristics of infections and the methods to diagnose C. auris over a period of three years in a tertiary care hospital. METHODS: Patients admitted between 2018 and 2020, who had candidemia due to C. auris were included in the study. Identification was performed using HiCrome™ Candida Differential Agar, Vitek 2 (BioMérieux, Inc., Marcy-l'Etoile, France) and MALDI-TOF, Vitek-MS. Identification was confirmed by detection of rDNA region covering part of 5.8S, entire of ITS2, and part of 28S by polymerase chain reaction (PCR). Biofilm formation was assessed by crystal violet staining. RESULTS: Presence of central line and broad spectrum antimicrobials were noted in all patients whereas total parenteral nutrition was given in 82.1% of these patients. Identification by Vitek2 v8.1 correlated with MALDI-TOF MS. PCR products of length 163 â€‹bp were obtained in all isolates as visualized by agarose gel electrophoresis. The biofilm quantity measured as A560 of the twenty-eight C. auris isolates ranged from 0.16 to 0.80 compared to C. albicans. CONCLUSIONS: C. auris can be identified by PCR targeting specific rDNA region. Biofilm formation and quantification can be achieved by growing C. auris isolates in Mueller-Hinton broth over a duration of 48 â€‹h.

E. hirae Causing Biliary Tract Infection in a Patient with Cholangiocarcinoma: A Case Report.

INTRODUCTION: E. faecium and E. faecalis are the common species of Enterococcus responsible for the majority of infections. Earlier, species other than the common ones were usually unidentified and reported as Enterococcus species. However, modern equipment, like MALDI-TOF and VITEK2, have been utilitarian, helping us to identify the previously unidentified species. E. hirae is an organism seldom reported to cause human infections. Here, we report a case of a biliary tract infection in a female patient with cholangiocarcinoma caused by E. hirae. CASE: A 56-year-old female presented with fever and abdominal pain. Bile aspirated during the ERCP was received in our laboratory. The gram stain of the bile sample revealed abundant polymorphonuclear leucocytes along with gram-positive diplococci. The organism failed to grow on MacConkey agar. On blood agar, non-hemolytic colonies grew. The organism was identified as E. hirae by MALDI-TOF MS. The antibiotic susceptibility performed using VITEK2 revealed it to be resistant to high-level gentamicin and susceptible to all remaining drugs. She was successfully treated with oral ciprofloxacin for the infection. DISCUSSION: Bile is colonized with bacteria due to obstruction in the biliary tree, leading to cholangitis. This causes bacterial proliferation and translocation of bacteria into the systemic circulation. Our case was resistant to high-level gentamicin, while all previously reported cases were susceptible. The resistant isolates of E. hirae being isolated from cattle and their surroundings amidst the rampant use of antibiotics in livestock can pose a difficult situation for humans. Thus, there should be regulations on antibiotic usage in livestock. Cases like these should be reported and recognized for their potential to cause outbreaks if they remain unreported. CONCLUSION: Thus, E. hirae, when encountered, should not be ignored but considered a pathogen and reported. The presence of drug-resistant organisms in cattle and their surroundings, their zoonotic potential to cause infections in humans, and the uncontrolled usage of antibiotics in livestock are causes for concern. Thus, we need to be more vigilant regarding it in the future.

Infection Trends, Susceptibility Pattern, and Treatment Options for Stenotrophomonas maltophilia Infections in Trauma Patients: A Retrospective Study.

Introduction Stenotrophomonas maltophilia is an emerging environmental, gram-negative, multidrug-resistant organism, associated with risk factors such as prolonged hospitalization, invasive procedures, admission to the intensive care unit, mechanical ventilation, use of indwelling catheters, administration of immunosuppressants or corticosteroids, human immunodeficiency virus infection, underlying malignancy, and organ transplantation. The organism, despite being of low invasiveness in immune-competent individuals, is difficult to treat because of intrinsic resistance to several antimicrobial agents. Materials and Methods This study focuses on commonly encountered resistance from among the isolates over a duration of 7 years from 2012 to 2018, analyzed retrospectively. Identification and susceptibility testing were performed using Vitek 2 (BioMérieux, Marcy-l'Etoile, France). Results Bloodstream infections were found to be most common (52.02%), followed by respiratory infections (35.83%). The median age of the patients was 36 years, and male to female ratio was 143:27. The median duration of hospital stay was 18 days, and mortality was seen in 18.82% of patients. Susceptibility to cotrimoxazole and levofloxacin was seen in 97.1% of isolates (168 out of 173) and 90.1% of isolates (156 out of 173), respectively. Conclusion Despite being effective in a majority of S . maltophilia isolates, both cotrimoxazole and levofloxacin have their shortcomings. Cotrimoxazole is bacteriostatic and can cause bone marrow suppression and resistance to levofloxacin sometimes develops during therapy. Thus, the therapy should be decided considering the characteristics of both of these drugs.

Evaluation of Peri-Implant Parameters and C-Reactive Protein Levels among Patients with Different Obesity Levels.

Background: Assessment of correlation between peri-implant parameters and C-reactive protein levels among patients with different obesity levels. Materials and Methods: Evaluation of 60 subjects was performed who were scheduled to undergo dental implant therapy for missing mandibular first molars. Three study cohorts were formed, namely, Group A: obese group (BMI between 30 Kg/m2 and 34.9 Kg/m2), Group B: high obese group (BMI over 34.9 Kg/m2), and Group C: non-obese group (BMI under 25 Kg/m2). Each cohort comprised 20 subjects. Dental implant therapy was carried out in all the patients. Peri-implant variables were evaluated in all the patients. Blood samples were obtained, and C-reactive protein levels in subjects having different obesity levels. Statistical analysis was performed using SPSS software. Results: Mean serum C-reactive protein levels among patients of groups A, B, and C occurred to be 3.28 mg/L, 3.65 g/L, and 3.61 g/L, respectively. On comparing numerically, noticeable outcomes were achieved. Mean probing depth among subjects of groups A, B, and C occurred to be 2.9 mm, 3.2 mm, and 1.3 mm, respectively. Mean marginal bone loss among subjects of groups A, B, and C occurred to be 2.1 mm, 2.7 mm, and 0.8 mm, respectively. On comparing numerically, noteworthy outcomes were gathered. Conclusion: There were significantly higher deranged peri-implant inflammatory variables among patients with higher levels of obesity.

Microbiological Profile and the Resistance Pattern of Pathogens in Neurosurgical Patients from a New Delhi Trauma Center.

BACKGROUND: Neurosurgical patients are considered to be at higher risk for infections including nosocomial infections compared with other critically ill individuals. Empirical antimicrobial therapy is of utmost importance for the survival of infected neurosurgical patients. METHODS: The microbial distribution and antimicrobial resistance patients from January 2012 to December 2021 (10 years) were analyzed retrospectively. Identification was done using VITEK-2 and MALDI-TOF systems. Antimicrobial susceptibility testing was determined by the Kirby Bauer Disk Diffusion Agar method (Clinical and Laboratory Standards Institute) and VITEK-2. RESULTS: A total of 48,474 samples were received, out of which 10,134 (21%) had growth. Respiratory specimens showed the maximum isolation of pathogens (42% n = 4292). The predominant bacterial pathogens were gram negative (n = 8972; 88.5%), whereas gram positives were only 11.5% (n = 1162) of the total organisms. Among the gram positives, the most common was Staphylococcus aureus (64.6%), and among gram negatives, the most common pathogen was Acinetobacter baumanni (38.6%). The weighted average of the drug-resistance profile across all gram positives was >50% for fluoroquinolones (levofloxacin, ciprofloxacin), gentamicin, erythromycin, and ampicillin, and in the case of gram negatives it was >90% for ampicillin-sulbactam, ticarcillin, cefazolin, cefotaxime, and ceftriaxone. Thirty-two patients were found to have candidemia, out of which 6 were C. albicans and the rest were nonalbican. Six neurosurgery patients had infection with C. auris, 4 from blood samples and 2 from urine. CONCLUSIONS: This study will add to the current knowledge and provide a better understanding of pathogen profile and resistance patterns in traumatic brain injury patients.

Design, synthesis and evaluation of novel pyrrole-hydroxybutenolide hybrids as promising antiplasmodial and anti-inflammatory agents.

In the pursuance of novel scaffolds with promising antiplasmodial and anti-inflammatory activity, a series of twenty-one compounds embraced with most promising penta-substituted pyrrole and biodynamic hydroxybutenolide in single skeleton was designed and synthesized. These pyrrole-hydroxybutenolide hybrids were evaluated against Plasmodium falciparum parasite. Four hybrids 5b, 5d, 5t and 5u exhibited good activity with IC50 of 0.60, 0.88, 0.97 and 0.96 µM for chloroquine sensitive (Pf3D7) strain and 3.92, 4.31, 4.21 and 1.67 µM for chloroquine resistant (PfK1) strain, respectively. In vivo efficacy of 5b, 5d, 5t and 5u was studied against the P. yoelii nigeriensis N67 (a chloroquine-resistant) parasite in Swiss mice at a dose of 100 mg/kg/day for 4 days via oral route. 5u was found to show maximum 100% parasite inhibition with considerably increased mean survival time. Simultaneously, the series of compounds was screened for anti-inflammatory potential. In preliminary assays, nine compounds showed more than 85% inhibition in hu-TNFα cytokine levels in LPS stimulated THP-1 monocytes and seven compounds showed more than 40% decrease in fold induction in reporter gene activity analyzed via Luciferase assay. 5p and 5t were found to be most promising amongst the series, thus were taken up for further in vivo studies. Wherein, mice pre-treated with them showed a dose dependent inhibition in carrageenan induced paw swelling. Moreover, the results of in vitro and in vivo pharmacokinetic parameters indicated that the synthesized pyrrole-hydroxybutenolide conjugates abide by the required criteria for the development of orally active drug and thus this scaffold can be used as pharmacologically active framework that should be considered for the development of potential antiplasmodial and anti-inflammatory agents.

Comparison of Abbott ID NOW, a novel isothermal amplification based COVID-19 diagnostic method with RTPCR.

BACKGROUND: The emergent crisis of the COVID-19 pandemic has posed enormous challenges for clinical laboratories to speed up diagnostics. The current reference standard for the diagnosis of COVID-19 is real time reverse transcriptase PCR on various platforms. However, even with automation, the turnaround time is huge enough to keep up with ever increasing numbers of patients. With increasing surge of COVID cases we need rapid diagnostic tests with good sensitivity and specificity. OBJECTIVES: Comparison between Abbott ID NOW COVID-19 and real time reverse transcriptase PCR as a reference method. MATERIALS AND METHODS: Specimens from seventy-two individuals were obtained over a period of two months which were processed for ID NOW and RTPCR at a dedicated COVID-19 centre of AIIMS. Dry nasal swabs were used for ID NOW while nasopharyngeal swabs along with throat swab were used for RTPCR. Among the participants, 15 were healthcare workers. Mild COVID was seen in 36 participants, moderate in 19 and severe in 9. Eight participants had non COVID illness. RESULTS: From the given samples, we observed that ID NOW has a sensitivity of 93.22% (55/59) specificity 100% (13/13), PPV 100% (55/55) and NPV 76.47% (13/17). CONCLUSION: ID NOW is a convenient, rapid molecular test which makes it suitable for both in laboratory use and as a point of care test. It can be a rapid rule-in test for COVID-19. Negative results, however, have to be interpreted as per the context.

Secondary Bacterial Infections in Mucormycosis-COVID-19 Cases: Experience during the Second COVID-19 Wave in India.

In the second wave of COVID-19 in India, there was a new challenge in the form of mucormycosis. Coinfection with mucormycosis was perilous as both conditions required a prolonged hospital stay, thus serving as an ideal platform for secondary infections. Using a retrospective observational study, we studied secondary infections and their impact on the outcome in COVID-19 patients with mucormycosis. The outcome in these patients was evaluated and compared with COVID-19 patients with mucormycosis but without any secondary infection. SPSS V-20 was used for data analysis. Fifty-five patients tested positive for mucormycosis (55/140; 39.28). Twelve out of these 55 (21.8%) developed secondary infections during their hospital stay. Bloodstream infection was the most common (42.86%) secondary infection. The Gram-negative (GN) organisms were more common (11/16; 68.75%) compared with the Gram-positives (GP) (5/16; 31.25%). But the most common isolate was Enterococcus faecium (5/16; 31.25%). A high percentage of microorganisms isolated were multidrug-resistant (15/16; 93.75%). Two out of five (40%) isolates of Enterococcus faecium were vancomycin-resistant (VRE). High resistance to carbapenems was noted in the GN isolates (9/11; 81.81%). The comparison of length of stay in both subgroups was statistically significant (P value <0.001). When compared, the length of stay in people with adverse outcomes was also statistically significant (P value <0.001). Procalcitonin (PCT) had a positive predictive value for the development of secondary bacterial infections (P value <0.001). Antimicrobial stewardship and strict infection control practices are the need of the hour. IMPORTANCE Although our knowledge about COVID-19 and secondary infections in patients is increasing daily, little is known about the secondary infections in COVID-19-mucormycosis patients. Thus, we have intended to share our experience regarding this subgroup. The importance of this study is that it brings to light the type of secondary infections seen in COVID-19-mucormycosis patients. These secondary infections were partially responsible for the mortality and morbidity of the unfortunate ones. We, as health care workers, can learn the lesson and disseminate the knowledge so that in similar situations, health care workers, even in other parts of the world, know what to expect.

Dynamical Study of an Eco-Epidemiological Delay Model for Plankton System with Toxicity.

In this paper, we analyze the complexity of an eco-epidemiological model for phytoplankton-zooplankton system in presence of toxicity and time delay. Holling type II function response is incorporated to address the predation rate as well as toxic substance distribution in zooplankton. It is also presumed that infected phytoplankton does recover from the viral infection. In the absence of time delay, stability and Hopf-bifurcation conditions are investigated to explore the system dynamics around all the possible equilibrium points. Further, in the presence of time delay, conditions for local stability are derived around the interior equilibria and the properties of the periodic solution are obtained by applying normal form theory and central manifold arguments. Computational simulation is performed to illustrate our theoretical findings. It is explored that system dynamics is very sensitive corresponding to carrying capacity and toxin liberation rate and able to generate chaos. Further, it is observed that time delay in the viral infection process can destabilize the phytoplankton density whereas zooplankton density remains in its old state. Incorporation of time delay also gives the scenario of double Hopf-bifurcation. Some control parameters are discussed to stabilize system dynamics. The effect of time delay on (i) growth rate of susceptible phytoplankton shows the extinction and double Hopf-bifurcation in the zooplankton population, (ii) a sufficiently large value of carrying capacity stabilizes the chaotic dynamics or makes the whole system chaotic with further increment.

Glaciohydrology of the Himalaya-Karakoram.

Understanding the response of Himalayan-Karakoram (HK) rivers to climate change is crucial for ~1 billion people who partly depend on these water resources. Policy-makers tasked with sustainable water resources management require an assessment of the rivers' current status and potential future changes. We show that glacier and snow melt are important components of HK rivers, with greater hydrological importance for the Indus basin than for the Ganges and Brahmaputra basins. Total river runoff, glacier melt, and seasonality of flow are projected to increase until the 2050s, with some exceptions and large uncertainties. Critical knowledge gaps severely affect modeled contributions of different runoff components, future runoff volumes, and seasonality. Therefore, comprehensive field observation-based and remote sensing-based methods and models are needed.

Externally Recurrent Neural Network based identification of dynamic systems using Lyapunov stability analysis.

This paper proposes an Externally Recurrent Neural Network (ERNN) for approximating the unknown dynamics of complex nonlinear systems and time series prediction. The proposed model utilizes the present as well as delayed values of the system outputs as well as of the external input. The weight update equations are tested for their boundedness by applying the Lyapunov stability method. Further, the error convergence proof is also given. The proposed model is put to test by considering various nonlinear examples and its performance is also compared with other state of the art methods. The results obtained in the present study indicate that the method is efficient and has provided accurate results.

Identification and control of dynamical systems using different architectures of recurrent fuzzy system.

Fuzzy logic based systems are very widely used for modeling and control of complex non-linear, plants. Fuzzy systems require the knowledge about the structure of the dynamic plant in order to achieve fruitful results. Recurrent Fuzzy systems (RFS) are a variation of fuzzy systems and have the ability to model and control dynamic plants without using the information about the structure of the plant. This paper presents identification and control of non-linear dynamical systems using two different architectures of recurrent fuzzy system (RFS). It highlights the importance of RFS over the conventional type-1 fuzzy based system. The objective of system identification as well as control has been achieved using both the architectures of RFS and the simulation results clearly show their efficiency. This paper also highlights yet another advantage of RFS over the conventional type-1 fuzzy systems which comes into light when dealing with higher order systems. The paper explains how the computational complexity can be greatly reduced by using RFS for higher order dynamical systems. A comparative analysis between the conventional type-1 fuzzy system and the two recurrent fuzzy systems has also been performed.

Temporally local recurrent radial basis function network for modeling and adaptive control of nonlinear systems.

In this paper, a novel temporally local recurrent radial basis function network for modeling and adaptive control of nonlinear systems is proposed. The proposed structure consists of recurrent hidden neurons having weighted self-feedback loops and a weighted linear feed-through from the input layer directly to the output layer neuron(s). The dynamic back-propagation algorithm is developed and used for updating the parameters of the proposed structure. To improve the performance of learning algorithm, discrete Lyapunov stability method is used to develop an adaptive learning rate scheme. This scheme ensures the faster convergence of the parameters and maintains the stability of the system. A total of 5 complex nonlinear systems are used to test and compare the performance of the proposed network with other neural network structures. The disturbance rejection tests are also carried out to check whether the proposed scheme is able to handle the external disturbance/noise signals effects or not. The obtained results show the efficacy of the proposed method.