Sensorless fractional order composite sliding mode control design for wind generation system

A high-performance control system is essential to transfer maximum power from wind power generation system (WPGS) to the utility grid. In this paper, a fuzzy fractional-order terminal sliding mode control (Fuzzy-FOSMC) is presented based on the boundary layer approach. This boundary layer approach leads to the trade-off between chattering elimination and control performances. Initially a fractional order terminal sliding mode control (FOTSMC) is designed in this paper. Then, the reaching control part of the FOTSMC is replaced by a fuzzy system that eliminates the chattering even in the presence of lumped parametric uncertainties. The fuzzy control part is designed such that:(a) it maintains the stability of the system by introducing a non-linear slope inside the thin boundary layer near the sliding surface, and (b) it eliminates the chattering by acting like a saturation function. A novel wind speed estimation technique is also proposed in this paper based on Gaussian process regression (GPR). The inputs to the GPR framework are selected as the wind turbine power and its rotational speed. The superior performance of the proposed wind speed estimation technique is verified using error comparison with pre-existing techniques. The stability of the proposed GPR-based Fuzzy-FOSMC control paradigm is ensured by using the Lyapunov stability theorem. The proposed paradigm is compared with benchmark sliding mode control (SMC) and FOTSMC strategies. The proposed Fuzzy-FOSMC performance in terms of chattering elimination and stability is validated under normal conditions and lumped parametric uncertainties using extensive simulations in Matlab/SIMULINK and processor in the loop based experimental workbench.

Adaptive Robust Trajectory Tracking Control of Multiple Quad-Rotor UAVs with Parametric Uncertainties and Disturbances

Recently, formation flying of multiple unmanned aerial vehicles (UAVs) found numerous applications in various areas such as surveillance, industrial automation and disaster management. The accuracy and reliability for performing group tasks by multiple UAVs is highly dependent on the applied control strategy. The formation and trajectories of multiple UAVs are governed by two separate controllers, namely formation and trajectory tracking controllers respectively. In presence of environmental effects, disturbances due to wind and parametric uncertainties, the controller design process is a challenging task. This article proposes a robust adaptive formation and trajectory tacking control of multiple quad-rotor UAVs using super twisting sliding mode control method. In the proposed design, Lyapunov function-based adaptive disturbance estimators are used to compensate for the effects of external disturbances and parametric uncertainties. The stability of the proposed controllers is guaranteed using Lyapunov theorems. Two variants of the control schemes, namely fixed gain super twisting SMC (STSMC) and adaptive super twisting SMC (ASTSMC) are tested using numerical simulations performed in MATLAB/Simulink. From the results presented, it is verified that in presence of disturbances, the proposed ASTSMC controller exhibits enhanced robustness as compared to the fixed gain STSMC.

Analysis and Evaluation of COVID-19 Web Applications for Health Professionals: Challenges and Opportunities

The multidisciplinary nature of the work required for research in the COVID-19 pandemic has created new challenges for health professionals in the battle against the virus. They need to be equipped with novel tools, applications, and resources-that have emerged during the pandemic-to gain access to breakthrough findings; know the latest developments; and to address their specific needs for rapid data acquisition, analysis, evaluation, and reporting. Because of the complex nature of the virus, healthcare systems worldwide are severely impacted as the treatment and the vaccine for COVID-19 disease are not yet discovered. This leads to frequent changes in regulations and policies by governments and international organizations. Our analysis suggests that given the abundance of information sources, finding the most suitable application for analysis, evaluation, or reporting, is one of such challenges. However, health professionals and policy-makers need access to the most relevant, reliable, trusted, and latest information and applications that can be used in their day-to-day tasks of COVID-19 research and analysis. In this article, we present our analysis of various novel and important web-based applications that have been specifically developed during the COVID-19 pandemic and that can be used by the health professionals community to help in advancing their analysis and research. These applications comprise search portals and their associated information repositories for literature and clinical trials, data sources, tracking dashboards, and forecasting models. We present a list of the minimally essential online, web-based applications to serve a multitude of purposes, from hundreds of those developed since the beginning of the pandemic. A critical analysis is provided for the selected applications based on 17 features that can be useful for researchers and analysts for their evaluations. These features make up our evaluation framework and have not been used previously for analysis and evaluation. Therefore, knowledge of these applications will not only increase productivity but will also allow us to explore new dimensions for using existing applications with more control, better management, and greater outcome of their research. In addition, the features used in our framework can be applied for future evaluations of similar applications and health professionals can adapt them for evaluation of other applications not covered in this analysis.

Novel algebraic meal disturbance estimation based adaptive robust control design for blood glucose regulation in type 1 diabetes patients

This study designs a robust closed-loop control algorithm for elevated blood glucose level stabilisation in type 1 diabetic patients. The control algorithm is based on a novel control action resulting from integrating algebraic meal disturbance estimator with back-stepping integral sliding mode control (BISMC) technique. The estimator shows finite time convergence leading to accurate and fast estimation of meal disturbance. Moreover, compensation of the estimated disturbance in controller provides significant reduction in chattering phenomenon, which is inherent drawback of sliding mode control (SMC). The controller is applied to one of the most reliable models of type 1 diabetic patients, named Bergman's minimal model. The effectiveness and superiority of the designed controller is shown by comparing it to classical SMC and super-twisting sliding mode control. The designed controller is subject to three different cases for detailed analysis of the controller's robustness against meal disturbance. The three cases considered are hyperglycaemia, hyperglycaemia combined with meal disturbance and three meal disturbance. The simulation results confirm superior performance of algebraic disturbance estimator based BISMC controller for all the cases mentioned above.

Morphology and ectoparasite spectrum of Pteropus vampyrus (the flying fox) in different parts of Malakand Division, Pakistan

Three districts viz. Lower Dir, Swat and Shangla in Khyber Pakhtunkhwa province, were surveyed for the collection of Pteropus vampyrus (the Indian flying fox) in Malakand division, the north western region of Pakistan from February to November 2018. A total of 35 specimens were captured. Out of the examined specimens 22 were found to be infected with ectoparasites. Three types of ectoparasites were observed including flies 20% (n=7/35), mites 28.5% (n=10/35) and bugs 14.2% (n=5/35). Male bats were more infected 57.1% (n=20/35) as compared to females 42.8% (n=15/35), however, no significant difference (p>0.05) was noted. Flies were recovered from wings membrane and head region, mites were found on wings, ears and around eyes while bugs were found attached on body surface and neck region. Body weight, circumference and wing span of male bats were greater as compared to female bats and were considered a key factor in clear cut identification of male and female Pteropus vampyrus (the Indian flyingfox). It was concluded that Pteropus vampyrus from north western part of Pakistan were parasitized by a varied parasite fauna with high infestation rates. We assume that in male bats the number of parasites is generally higher than in females. Our results revealed new insights into parasite fauna of Pteropus vampyrus.

Design & thermal modeling of solar panel module with embedded reconfigurable Air-Coil for micro-satellites

Spacecrafts need to maneuver their solar panels towards the sun and antennas towards the ground station for maximum solar power harvesting and communication with the ground station. For tracking purpose, usually magnetorquer rods, reaction wheels and permanent magnets are used, but they are heavier, expensive, and occupy extra space on the spacecraft. Keeping in mind the dimension, budget and mass constraints of small satellites, a system compatible with small satellite is worth consideration. Consequently, this paper focuses on designing and analyzing a solar panel module with embedded Air-Coil. Such an Air-Coil is an innovative idea for the replacement of heavier, bulky and expensive attitude control systems. The proposed Air-Coil is integrated in the internal layers of an eight layers solar panel PCB module. Complete degradation analyses of the solar panel have been done to ensure that it will meet the satellite power requirements at BOL (beginning of life) and EOL (end of life). The proposed embedded Air-Coil has been analyzed for the generated magnetic moment, resultant torque, power consumption and temperature increase of the complete solar panel unit. A steady state thermal model is proposed to measure the thermal resistance between top and bottom layers of the solar panel module, which gives an idea about the heat trapped inside the solar panel module. The designed embedded Air-Coil is fully reconfigurable where coil in each layer can be operated as a separate coil. The four coils in different layers can be attached or detached through switches in different configurations i.e. single coil, four in series, four in parallel, and their hybrid combinations. The analyses of power consumption, heat dissipation, temperature rise, magnetic moment and torque generation by different configurations of the designed Air-Coil have been performed. The generated magnetic moment is very high i.e. around 12Am², which is enough to rotate a microsatellite by 90° in 200s. The efficacy of the proposed module is significantly higher than the already available systems with respect to mass, price, power dissipation, heat generation, and dimension.

Cryopreservation Of Nili-Ravi Buffalo Bull Sperm in Cryodiluent Supplemented with Lolium perenne Protein Preparations

BACKGROUND

Semen from the Nili-Ravi buffalo bull, Bubalus bubalis, shows poor survival after freeze storage compared to bovine (Bos taurus and Bos indicus) semen. Freeze-susceptibility distinctions in these two genera have been attributed to differences in sperm membranes.

MATERIALS AND METHODS

We measured the impact of protein preparations derived from a frost-resistant perennial grass, Lolium perenne, with ice recrystallization inhibition activity on the low temperature storage of B. bubalis semen.

RESULTS

When the L. perenne preparations (0.1, 1, 10 µg/mL) were added to buffalo semen [2 ejaculates per bull (N=3) per replicate (r=3)] in Tris-citrate extender (50×10⁶sperm mL^-1), there was no impact on semen quality, as measured by sperm motility and plasma membrane integrity, after storage at 4 degree C (P>0.05). However, when semen supplemented with the grass proteins (0.1 and 1 µg mL^-1) was evaluated after freezing and storage in liquid nitrogen for 24 h, post-thaw sperm progressive motility and plasma membrane integrity was higher (P<0.05) than in control samples. Post-thaw sperm viability and sperm acrosome integrity was similar (P > 0.05) to controls.

CONCLUSION

The improvement in cryopreserved buffalo sperm progressive motility and plasma membrane integrity suggests that the use of these easily-made preparations may improve fertility after cryopreservation and offers the prospect of improved conception rates after artificial insemination with cryopreservation.

Efficiency of antifreeze glycoproteins for cryopreservation of Nili-Ravi (Bubalus bubalis) buffalo bull sperm

Experiments were conducted to evaluate the effect of Antarctic fish antifreeze glycoproteins, (AFGP) size 1-5 (34-10.5 kDa) and 7-8 (3.2 and 2.4 kDa) in extender on buffalo bull sperm at cooling (4 °C) and at post thawing. Semen was collected from three Nili-Ravi buffalo bulls with artificial vagina for 3 weeks. Qualifying ejaculates from each buffalo bull were diluted (at 37 °C having 50×10(6) sperm/mL) in tris-citric acid extender containing AFGP at 0 (control), 0.1, 1 and 10 μg/mL. An aliquot of diluted semen was evaluated for sperm progressive motility and plasma membrane integrity, while the remaining fraction was cooled to 4 °C in 2 h. Further, an aliquot of cooled semen was evaluated for the previously described variables and the remaining fraction was cryopreserved (-196 °C). After 24 h of storage, straws were thawed at 37 °C for 30 s to assess post-thaw sperm quality. Inclusion of AFGP in the extender did not affect (P>0.05) sperm progressive motility and plasma membrane integrity of buffalo bull sperm at cooling stage (4 °C). However, at post thawing, improvement (P<0.05) in sperm progressive motility and plasma membrane integrity was recorded in extender containing AFGP 1-5 and AFGP 7-8 at 1 μg/mL compared to the control. Percentage of live sperm with an intact acrosome remained similar (P>0.05) in extenders containing different amounts of AFGP and control. In conclusion, supplementation of 1 μg/ml of AFGP in extender improved the motility and plasma membrane integrity of Nili-Ravi buffalo sperm after thawing.

Arachidic acid in extender improves post-thaw parameters of cryopreserved Nili-Ravi buffalo bull semen

Cryopreservation process reduces lipids and phospholipids from buffalo bull spermatozoa. It was therefore hypothesized that supplementation of fatty acid to extender may improve the post-thaw quality of buffalo semen. The objective was to evaluate the effect of arachidic acid supplementation in extender on post-thaw quality of buffalo bull (Bubalus bubalis) spermatozoa. Semen was collected from three adult Nili-Ravi buffalo bulls of similar age group with artificial vagina (42°C) for 3 weeks (replicate). Qualified semen ejaculates (n = 18) were split into four aliquots and diluted in tris-citric acid extender containing 0.0 (control), 5.0, 10.0 and 20.0 ng/ml at 37°C having approximately 50 × 10(6) spermatozoa/ml. Diluted semen was cooled to 4°C in 2 h and equilibrated for 4 h at 4°C. Cooled semen was filled in 0.5-ml straws at 4°C, kept on liquid nitrogen vapours for 10 min and plunged in liquid nitrogen for storage. Thawing of frozen semen was performed after 24 h at 37°C for 30 s. Sperm progressive motility (%) was improved in a dose-dependent manner by supplementing arachidic acid at 5.0, 10.0 and 20.0 ng/ml compared with control. Structural and functional integrity of sperm plasma membrane (%), number of acrosome-intact live sperm (%) and sperm chromatin integrity (%) were better (p < 0.05) in extender having 5.0 ng/ml of arachidic acid compared with control. At 10.0 ng/ml, these values did not vary (p > 0.05) from those at 5.0 ng/ml. Further improvement in structural and functional integrity of sperm plasma membrane, number of acrosome-intact live sperm and chromatin integrity was observed at 20.0 ng/ml of arachidic acid in extender. In conclusion, arachidic acid supplementation in extender improved the post-thaw quality parameters of cryopreserved Nili-Ravi buffalo bull spermatozoa. Among the arachidic acid concentrations studied, maximum improvement in post-thaw semen quality parameters was observed at 20.0 ng/ml.

Cymbopogon citratus Protects against the Renal Injury Induced by Toxic Doses of Aminoglycosides in Rabbits

Renal injury is the most common side-effect of aminoglycosides. These antimicrobial drugs are particularly effective against Gram-negative microorganisms. The present study was conducted to investigate the renal protective activity of Cymbopogon citratus in gentamicin-induced nephrotoxicity. Male rabbits were divided into four groups (n=6) including group 1 (0.9% saline treated), group 2 (80 mg/kg/day gentamicin-treated), group 3 (200 mg/kg/day Cymbopogon citratus treated) and group 4 (80 mg/kg/day gentamicin and 200 mg/kg/day Cymbopogon citratus treated). Biochemical kidney functioning parameters, urinary enzymes and histopathological examination were performed. The results of the present study showed that simultaneous administration of Cymbopogon citrates and gentamicin significantly protected alteration in body weight, blood urea nitrogen, serum creatinine, creatinine clearance, serum uric acid, serum electrolytes, urinary volume, urinary protein, urinary lactate dehydrogenase and urinary alkaline phosphatase induced by gentamicin. Histological examination of the kidney also suggested the same. It is concluded from the current study that co-administration of Cymbopogon citratus with gentamicin for 3 weeks successfully prevented renal damage associated with aminoglycosides.