Development and Control of Generator-Converter Topology for Direct-Drive Wind Turbines

In this chapter, a new topology for Direct-Drive Wind Turbines (DDWTs) with a low-voltage generator design is presented in order to eliminate the required dc-bus capacitors or dc-link inductors. In the presented topology, the grid-side converter is replaced by a boost Current Source Inverter (CSI) therefore removing the need for the dc-bus electrolytic capacitors which results in increasing the system lifetime. In the developed topology, the synchronous inductance of the generator is utilized. This facilitates the elimination of the intrinsically required dc-link inductor in the CSI which further contributes to a reduction in the overall system weight and size. The boost CSI is capable of converting a low dc voltage to a higher line-to-line voltage. This results in the implementation of a low-voltage generator for DDWTs. The feasibility of the presented low-voltage generator is investigated through Finite Element (FE) computations. In this chapter, a modified 1.5 MW low-voltage generator for the proposed topology is compared with an existing 1.5 MW Permanent Magnet (PM) synchronous generator for DDWTs. The feasibility of the presented topology of generator-converter for DDWTs is verified through simulations and laboratory tests. Furthermore, the controls developed for the developed wind turbine topology is also presented in this chapter

Difference-in-Differences with a Misclassified Treatment

This paper studies identification and estimation of the average treatment effect on the treated (ATT) in difference-in-difference (DID) designs when the variable that classifies individuals into treatment and control groups (treatment status, D) is endogenously misclassified. We show that misclassification in D hampers consistent estimation of ATT because 1) it restricts us from identifying the truly treated from those misclassified as being treated and 2) differential misclassification in counterfactual trends may result in parallel trends being violated with D even when they hold with the true but unobserved D*. We propose a solution to correct for endogenous one-sided misclassification in the context of a parametric DID regression which allows for considerable heterogeneity in treatment effects and establish its asymptotic properties in panel and repeated cross section settings. Furthermore, we illustrate the method by using it to estimate the insurance impact of a large-scale in-kind food transfer program in India which is known to suffer from large targeting errors

Pregnancy in unicornuate uterus without rudimentary horn: a case report

A unicornuate uterus is associated with numerous obstetric and gynaecological complications such as infertility, endometriosis, miscarriage, malpresentations, and intrauterine growth restriction. Around 2.3-13% of Mullerian duct anomalies present as unicornuate uterus. Management of unicornuate uterus is still uncertain and it leads to poorer pregnancy outcome. We present here a case of 26-year-old primigravida who presented to us with 40-weeks pregnancy associated with breech presentation. She was taken for elective caesarean section and intra-operatively she was found to have unicornuate uterus without rudimentary horn. Unicornuate uterus is associated with poor pregnancy outcome but a successful pregnancy is possible. Usual presentation of patients with unicornuate uterus is near their menarche and they have higher than usual gynaecological complications. Pregnancies in unicornuate uterus are prone to intra uterine growth restriction hence serial ultrasound should be done for regular fetal growth monitoring

Conditions associated with discarding of blood and its components in a blood bank of tertiary care hospital of Western Uttar Pradesh: a retrospective study

Background: Blood transfusion services in India rely on different factors for a smooth workout. Thus proper utilization of blood is necessary with minimal wasting. The aim was to evaluate the causes of discarding of blood and its components and to implement possible intervention for minimizing wastage. Methods: A retrospective study was carried out in the blood bank of Sardar Vallabh Bhai Patel Hospital, Lala Lajpat Rai Medical College, Meerut, Uttar Pradesh over a time period of 24 months from April 2019 to March 2021. Results: A total of 21627 units were collected from donors. A total of 11534 whole blood (WB), 10093 packed red blood cells (PRBC), 3245 platelets (PC), and 9669 fresh frozen plasma (FFP) were prepared. A total of 4046 units of blood and its components were discarded. The discard rate for WB, PRBC, PC and FFP was 6.25%, 7.46%, 38.39%, and 13.71% respectively. Conclusions: An average of 18.70% of blood units were discarded during this study period. The overall most common reason for discard was the date of expiry followed by transfusion transmitted infections (TTI). To minimize wastage of blood units, blood banks should be fully committed to organizing and coordinating the blood transfusion services,implementing all possible strategies as discussed in order to lower the discarding of blood and its units and to make them widely available

A numerical technique for solving multi-dimensional fractional optimal control problems using fractional wavelet method

This paper presents an efficient numerical method for solving fractional optimal control problems using an operational matrix for a fractional wavelet. Using well-known formulae such as Caputo and Riemann-Liouville operators to determine fractional derivatives and integral fractional wavelets, operational matrices were devised and utilised to solve fractional optimal control problems. The proposed method reduced the fractional optimal control problems into a system of algebraic equations. To validate the effectiveness of the presented numerical approach, some illustrative problems were solved using fractional Taylor and Taylor wavelets, and the approximate cost function value derived by approximating state and control functions was compared. In addition, convergence rate and error bound of the proposed method have been derived

Naringin a potent antioxidant used as bioavailibility enhancer for terbinafine hydrochloride

The poor bioavailability of drugs has been identified as the single most important challenge in oral drug delivery. Prominent among the factors responsible for this are the oxidative metabolic activity of the intestinal and hepatic cytochrome P450 enzyme family. Naringin and naringenin which are the major phytochemical component of grapefruit juice, a well-known cytochrome P450 3A4 inhibitor and flavone glycoside, is antioxidant in nature and occurs naturally in the pericarp of citrus fruit, and particularly of grapefruit (Citrus paradisii) where it is the predominant flavonoid found and is responsible for the bitter taste associated with the fruit. CYP3A4 which is a class of CYP – 450 (microsomal enzyme) is responsible for the oxidative metabolic reaction of various substrates which decreases the bioavailability of drug

The cosmological model in f(R,Tϕ) f(R,T^\phi) gravity with Scalar Field conformity

The homogeneous and isotropic cosmological model in generalized $f(R,T^\phi)$ theories associated with scalar field is discussed, which is motivated by the $f(R,T)$ theory of gravity studied by Harko et al. \cite{Harko:2011kv, Harko:2014pqa}. The $f(R,T^\phi)$ gravity can be explained as $f(R,T)$ gravity with a self-interacting scalar field $\phi$, where $T^\phi$ is the trace of the energy-momentum tensor. The parametrization of Hubble parameter $H(t)$ is taken as $\alpha-\beta e^{-\gamma t}$, where $\alpha$, $\beta$ and $\gamma$ are arbitrary constants such that $\alpha, \gamma>0$ and $\beta<0$. The model shows no space-time singularity and the expansion of the universe will continue forever, i.e., the future scenario of the universe attains Big Freeze. The model predicts the moderate inflationary scenario at the time of the evolution of the universe and it is consistent with $\Lambda$CDM in late times. The consistency of the model has also been examined using recent observational Hubble dataset and supernovae dataset. Finally, the physical features of the model have been discussed in some detail.Comment: 12 pages, 13 figure