Multi-Machine Stability Using Dynamic Inversion Technique

Stability studies of multi machine system are a major concern to power system engineers due to the increasing complexity involved. This paper deals with the application of a nonlinear technique called Dynamic Inversion, to TCSC for the improvement of stability of multi-machine system. The transient stability studies for various cases: without any controller, with 75% line compensation and with Dynamic Inversion technique, are compared. The critical clearing time as well as the maximum loading ability is also discussed. The result for the nonlinear controller is found to be better than all the other cases

Chorioangioma of Placenta: A Rare Placental Cause for Adverse Fetal Outcome

Chorioangioma is a benign angioma of placenta arising from chorionic tissue. Large chorioangioma has unfavourable effects on both mother and fetus. We describe a case with large chorioangioma that had a poor outcome on the fetus. We also reviewed the literature on prognostic factors affecting fetal outcome

One pot synthesis of substituted 1H-benzo[f]chromen-3-yl-2H-chromen-2-one derivatives

The title compounds, substituted 1H-benzo[f]chromen-3-yl-2H-chromen-2-ones were obtained by reacting 3-aryl-1-(3-coumarinyl)propen-1-ones with 2-napthol catalyzed by DBU (1,8-diazabicyclo[5,4,0]undec-7-ene) and concentrated H2SO4 in ample yields. Their structures were characterized by IR, 1H NMR, 13C NMR, mass spectral and elemental analysis. All the synthesized compounds have been evaluated for their in-vitro antibacterial activity against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa and antifungal activity against Aspergillus Niger and Candida albicans by using serial broth dilution method. Among those compounds 3 band 3c exhibits prominent results

Academic Stress and Adolescent Distress: The Experiences of 12th Standard Students in Chennai, India

Media reports and interviews with counselors indicate that academic stress and adolescent distress is a significant problem in India, but little systematic research has been conducted on the issue. A combination of quantitative and qualitative methods was used in the current study - surveys assessed the prevalence of academic stress and adolescent distress, and interviews with 12th standard students explored their perceptions of the issue and their understanding of the role of parents.In the survey part of the study, the prevalence of the problem was assessed with the use of scales that measured depression and anxiety. Surveys were completed by 12th standard students (n = 588) from the south Indian city of Chennai. A majority of students reported that they were stressed by the coming school year, and rates of depression and anxiety were very high in the sample. In contrast with previous research and contrary to expectations, few gender, academic track and school type differences were found. Further analyses indicated that different groups of students appeared to experience distress in different ways.Semi-structured interviews were conducted with 12th standard students (n = 24) to explore their perceptions of academic stress and adolescent distress. Their perceptions could be categorized into six themes: busy schedules, experience of stress, somatic symptoms, attitudes and beliefs about 12th standard, the role of God vs. hard work, and education reform. The same interview data was also used to understand the role of parents. Analysis suggested that parents were involved in their child's education in five ways - they had specific expectations for achievement, they put pressure on their children, they compared their child to others, they controlled the study environment, and they were supportive of their children. Some categories appeared to be associated with a greater experience of academic stress and adolescent distress than others. The interview data was also explored for gender, academic track, and school type differences.Jointly, these findings suggest that academic stress and adolescent distress is indeed a significant problem in Chennai, India. A variety of interventions are suggested to address the issue

CNDO [complete neglect of differential overlap]/2 studies on ion solvation

This article does not have an abstract

The effect on post-operative pain of intravenous clonidine given before induction of anaesthesia

Background: Treatment of acute post-thoracotomy pain is particularly important not only to keep the patient comfortable but also to minimize pulmonary complications. Aim: This study was designed to test the effect of pre-induction administration of clonidine, given as a single intravenous dose, on post-operative pain scores and fentanyl consumption in patients after thoracic surgery. Setting and Design: Tertiary referral centre. Prospective, randomised, double-blind, placebo-controlled trial. Methods: Sixty patients were randomly allocated to receive clonidine (3 mcg/kg) or saline pre-operatively before induction of anaesthesia. The primary endpoint was pain on coughing (visual analogue scale (VAS) 0-100 mm) 120 min after surgery, time to first analgesic injection in the post-anaesthesia care unit (PACU) and 24-h fentanyl consumption. Statistical Analysis: For between-group comparisons, t-test and U-test were used as appropriate after checking normality of distribution. The incidence of complications between the groups was compared by Fisher′s exact test. Results: The post-operative VAS for the first 120 min and the fentanyl consumption at 24 h was significantly greater in the placebo group compared with the clonidine group (P<0.05). The sedation score was increased in the clonidine group during study drug infusion, but did not differ significantly on admission to the PACU. Conclusions: A single intravenous dose of clonidine (3 mcg/kg) given before induction of anaesthesia significantly reduced the post-operative VAS score in the initial period and fentanyl consumption during 24 h after thoracic surgery

Hydrogen bonds formed by C—H groups

Thermodynamic data on the hydrogen bond equilibria in octyne-donor systems are reported. CNDO/2 calculations have been carried out on hydrogen bonds formed by acetylene, HCN and fluoroform. The calculated values of dissociation energies and C-H... donor distances are in fair agreement with the experimental data. Molecular orbital calculations indicate that there is no intramolecular hydrogen bond in ortho-nitrobenzaldehyde

Configuration of secondary amides and thioamides: spectroscopic and theoretical studies

Infrared spectroscopy has been employed to study the cis–trans-equilibria and ΔH values in secondary amides and thioamides. Based on these results, several generalizations have been made regarding the structural factors affecting the configurations. Solvent effects on the cis–trans-equilibria and on the barrier height to rotation in secondary amides have been investigated by i.r. and n.m.r. spectroscopy; the barrier height increases with solvent polarity. Proton-donor or -acceptor solvents significantly affect the cis–trans equilibrium in amides. Solvent effect and temperature effect studies on the n.m.r. and i.r. spectra of 8-, 9- and 13-lactams and their N-methyl derivatives show that in 9-lactam and N-methyl-13-lactam both cis- and trans-isomers are present. Molecular orbital calculations satisfactorily predict relative stabilities of the different configurations of secondary amide derivatives; oxygen protonation of amides is favoured over nitrogen protonation. In the O-protonated amides, the barrier height to rotation is appreciably larger than in the parent amides

Model-following Neuro-adaptive approach for robust control of high performance aircrafts

Based on dynamic inversion, a relatively straightforward approach is presented in this paper for nonlinear flight control design of high performance aircrafts, which does not require the normal and lateral acceleration commands to be first transferred to body rates before computing the required control inputs. This leads to substantial improvement of the tracking response. Promising results are obtained from six degree-offreedom simulation studies of F-16 aircraft, which are found to be superior as compared to an existing approach (which is also based on dynamic inversion). The new approach has two potential benefits, namely reduced oscillatory response (including elimination of non-minimum phase behavior) and reduced control magnitude. Next, a model-following neuron-adaptive design is augmented the nominal design in order to assure robust performance in the presence of parameter inaccuracies in the model. Note that in the approach the model update takes place adaptively online and hence it is philosophically similar to indirect adaptive control. However, unlike a typical indirect adaptive control approach, there is no need to update the individual parameters explicitly. Instead the inaccuracy in the system output dynamics is captured directly and then used in modifying the control. This leads to faster adaptation, which helps in stabilizing the unstable plant quicker. The robustness study from a large number of simulations shows that the adaptive design has good amount of robustness with respect to the expected parameter inaccuracies in the model