Optimal fractional sliding mode control for the frequency stability of a hybrid industrial microgrid

<abstract> <p>The rising proportion of inverter-based renewable energy sources in current power systems has reduced the rotational inertia of overall microgrid systems. This may cause high-frequency fluctuations in the system leading to system instability. Several initiatives have been suggested concerning inertia emulation based on other integrated external energy sources, such as energy storage systems, to combat the ever-declining issue of inertia. Hence, to deal with the aforementioned issue, we suggest the development of an optimal fractional sliding mode control (FSMC)-based frequency stabilization strategy for an industrial hybrid microgrid. An explicit state-space industrial microgrids model comprised of several coordinated energy sources along with loads, storage systems, photovoltaic and wind farms, is considered. In addition to this, the impact of electric vehicles and batteries with adequate control of the state of charge was investigated due to their short regulation times and this helps to balance the power supply and demand that in turn brings the minimization of the frequency deviations. The performance of the FSMC controller is enhanced by setting optimal parameters by employing the tuning strategy based on an iterative teaching-learning-based optimizer (ITLBO). To justify the efficacy of the proposed controller, the simulated results were obtained under several system conditions by using a vehicle simulator in a MATLAB/Simulink environment. The results reveal the enhanced performance of the ITLBO optimized fractional sliding mode control to effectively damp the frequency oscillations and retain the frequency stability with robustness, quick damping, and reliability under different system conditions.</p> </abstract>

Study of Methaemoglobin in Malaria Patients

To estimate the concentration of methemoglobin (MetHb) in malaria patients and correlate with severity of malaria infection. This prospective study included 30 untreated cases of malaria confirmed by Quantitative Buffy Coat (QBC) test and 30 age sex matched non-malarial cases taken as controls. All the patients underwent thorough clinical examination and routine biochemical investigation. Methemoglobin levels were estimated by spectrophotometric (co-oxymeter) method on day 1 and day 10 of diagnosis of all study group patients and correlated with clinical profile and severity. Out of 30 malaria patients 22 were males and eight were females. The clinical presentations in complicated malaria group (n = 21) were fever 21 (100 %), anemia 17 (80.95 %), renal failure 12 (52.38 %) and coma/convulsion 5 (23.8 %). The mean age of the study group was 41.66 years. Mean MetHb in complicated malaria on day 1 was 2.55 ± 1.75 % and day 10 was 10.69 ± 8.19 % (statistically significant). The overall mortality was 13 (43.33 %) among study group while 5 (16.66 %) was found among control group. Mean MetHb who died (n = 13) on day 1 was 3.144 ± 1.829 % and (n = 8) on day 10 it was 19.982 ± 8.406 %. Increase in level of methaemoglobin is detrimental to the body and is associated with increase in mortality. Routine MetHb estimation may be used as a prognostic indicator in the management of malaria patients. It is suggested that addition of drugs which reduce MetHb may be tried along with antimalarial drugs to decrease morbidity and mortality in malaria.

A novel high performance bismaleimide/diallyl bisphenol A (BMI/DBA)–epoxy interpenetrating network resin for rigid riser application

A new class of interpenetrating network (IPN) resin system was developed by mixing tetrafunctional epoxy resin (TGDDM) with diallyl bisphenol A (DBA) modified bismaleimide (BMI) for rigid riser applications at high temperatures of more than 280 °C.

Standardization of sulaharan yoga: an ayurvedic tablet formulation

Quality assurance of herbal products may be ensured by proper quality control of the herbal ingredients and by means of good manufacturing practice. We have developed a simple scheme for the standardization and authentication of Sulaharan Yoga a poly herbal formulation. Sulaharan Yoga was prepared as per Ayurvedic Formulary of India. In-house and marketed preparation has been standardized on the basis of organoleptic characters, physical characteristics and physico-chemical properties. The set parameters were found to be sufficient to standardize the Sulaharan Yoga and can be used as reference standards for the quality control/ quality assurance study.

Relationship of hepatic and renal dysfunction with haemorrheological parameters in Plasmodium falciparum malaria

OBJECTIVES

The present study was designed to assess hepatic and renal dysfunction in Plasmodium falciparum malaria, and evaluate if such abnormalities had any bearing with the hemorrheological dysfunction.

METHODS

Sixty consecutive patients of Plasmodium falciparum malaria with hepatic and renal dysfunction (Group A) and twenty consecutive cases of uncomplicated falciparum malaria (Group B) were studied. Patients with past history of alcoholism, jaundice, chronic renal failure, bleeding diathesis or coagulopathy were excluded from the study. Laboratory investigations done were liver and renal function tests, complete blood count and coagulation profile. The data collected was analysed to inter - correlate parameters of hepatic, renal and hemorrheological dysfunction.

RESULTS

In Group A, all had rigor and chill, icterus while 57% had oliguria and hepatomegaly, 37% splenomegaly, with less than 2% having overt bleeding diathesis. On evaluation, in Group A, 57% had acute renal failure, mean value of bilirubin was 13.91 (+/- 12.53) mg/dL, ALT 76.92 (+/- 37.48) IU/ml, AST 135.32 (+/- 97.33) IU/ml, mean PT was 13.03 (+/- 2.22) seconds, mean aPTT was 31.69 +/- 6.76 seconds, FDP by D-dimer was raised in 53% and LDH was raised in 78% respectively. In Group B mean PT was 11.93 (+/- 1.51) seconds, mean APTT was 29.39 +/- 2.89 seconds and FDP by D-dimer was raised in 30% respectively. Thrombocytopenia was seen in 26% cases in Group A and 15% cases in Group B. On analysis, in Group B, there was statistically significant negative correlation of total platelet count with serum AST (p = .010) and serum ALT (p = .036), serum ALP with BT (p = .036), but positively with CT (p = .006) and aPTT (p = .036). In Group A, serum bilirubin was found to have significant negative correlation with haemoglobin (p = .019),positive correlation with aPTT (p = .037), urea (p = .000) and serum creatinine (p = .000), serum ALP Positively with serum urea (p = .025) and serum creatinine (p = .037), serum urea negatively with haemoglobin(p = .015), so also did serum creatinine (p = .025),prothrombin time positively with serum urea(p = 0.037) and serum creatinine (p = 0.013), serum FDP positively with serum urea (p = 0.038) and serum creatinine (p = 0.022), bleeding time positively with serum AST(p = .002).

CONCLUSION

Despite less than 2% of patients in Group A having clinically overt bleeding diathesis, raised FDP (53%), prolonged aPTT (67%), low total platelet count (26%) and anemia (87%) were found in a significant number of patients, suggesting subclinical DIC. Therefore patients with Plasmodium falciparum malaria have high incidence of subclinical haemorrheological disorders which do not amount to overt DIC but adversely affect renal function contributing to acute renal failure.