Test results for composite specimens and elements containing joints and cutouts

A program was conducted to develop the technology for joints and cutouts in a composite fuselage that meets all design requirements of a large transport aircraft for the 1990s. An advanced trijet derivative of the DC-10 was selected as the baseline aircraft. Design and analysis of a 30-foot-long composite fuselage barrel provided a realistic basis for the test effort. The primary composite material was Hexcel F584 resin on 12 K IM6 fiber, in tape and broadgoods form. Fiberglass broadgoods were used in E-glass and S-glass fiber form in the cutout region of some panels. Additionally, injection-molded chopped graphite fiber/PEEK was used for longeron-to-frame shear clips. The test effort included four groups of test specimens, beginning with coupon specimens of mono-layer and cross-piled laminates, progressing through increasingly larger and more complex specimens, and ending with two 4- by 5-foot curved fuselage side panels. One of the side panels incorporated a transverse skin splice, while the second included two cabin window cutouts

Coherence Resonance in Chaotic Systems

We show that it is possible for chaotic systems to display the main features of coherence resonance. In particular, we show that a Chua model, operating in a chaotic regime and in the presence of noise, can exhibit oscillations whose regularity is optimal for some intermediate value of the noise intensity. We find that the power spectrum of the signal develops a peak at finite frequency at intermediate values of the noise. These are all signatures of coherence resonance. We also experimentally study a Chua circuit and corroborate the above simulation results. Finally, we analyze a simple model composed of two separate limit cycles which still exhibits coherence resonance, and show that its behavior is qualitatively similar to that of the chaotic Chua systemComment: 4 pages (including 4 figures) LaTeX fil

On Fuglede's conjecture for three intervals

In this paper we prove the "Tiling implies Spectral" part of Fuglede's paper for the case of three intervals. Then we prove the "Spectral implies Tiling" part of the conjecture for the case of three equal intervals as also when the intervals have lengths 1/2, 1/4, 1/4. For the general case we change our approach to get information on the structure of the spectrum for the n-interval case. Finally, we use symbolic computations on Mathematica, and prove this part of the conjecture with an additional assumption on the spectrum.Comment: 21 page

Forecasting minimum temperature during winter and maximum temperature during summer at Delhi

A knowledge of minimum temperature during winter and maximum temperature during summer is a very useful for individuals, as well as for organisations whose workers and machines have to operate in the open, e.g. the armed forces, railways, roadways, tourism, etc. Accurate forecasts of minimum temperature during winter help in the prediction of cold-wave conditions and those of maximum temperature during summer help in the prediction of heat-wave conditions over northern India. Models for forecasting the minimum temperature during December and the maximum temperature during May at Delhi have been developed using surface and upper-air meteorological data from 1984-89. The results of testing the models on independent data from recent years (1994-95) are presented. The results are encouraging and more than 80% of the forecasts are correct within ±2°C. Possible reasons for large deviations are also investigated

Forecasting of thunderstorms in the pre-monsoon season at Delhi

Accurate prediction of thunderstorms during the pre-monsoon season (April-June) in India is essential for human activities such as construction, aviation and agriculture. Two objective forecasting methods are developed using data from May and June for 1985-89. The developed methods are tested with independent data sets of the recent years, namely May and June for the years 1994 and 1995. The first method is based on a graphical technique. Fifteen different types of stability index are used in combinations of different pairs. It is found that Showalter index versus Totals total index and Jefferson's modified index versus George index can cluster cases of occurrence of thunderstorms mixed with a few cases of non-occurrence along a zone. The zones are demarcated and further sub-zones are created for clarity. The probability of occurrence/non-occurrence of thunderstorms in each sub-zone is then calculated. The second approach uses a multiple regression method to predict the occurrence/nonoccurrence of thunderstorms. A total of 274 potential predictors are subjected to stepwise screening and nine significant predictors are selected to formulate a multiple regression equation that gives the forecast in probabilistic terms. Out of the two methods tested, it is found that the multiple regression method gives consistently better results with developmental as well as independent data sets; it is a potential method for operational use

Drug-induced cutaneous adverse drug reactions in dermatology in Dr. B.R. Ambedkar Medical College

Background: Cutaneous adverse drug reactions (ADRs) affect 2-3% of hospitalized patients. The severity varies from mild itching to life-threatening Stevens-Johnson syndrome (SJS). Hence, this study was undertaken to emphasize the need to report ADRs.Methods: The study was carried out in the Department of Dermatology in Dr. B.R Ambedkar Medical College Hospital from June to December 2012. Naranjo’s algorithm was used to determine the causality of an ADR. Informed consent was obtained from each patient, and thorough clinical examination was conducted. All the information was carefully recorded in a pre-designed proforma. To establish the etiologic agent for a particular type of reaction, attention was paid to the drug history, temporal correlation with the drug, duration of the reaction, morphology of the reaction, associated mucosal or systemic involvement, improvement of lesions on withdrawal of the drug.Results: In the present study, all the age groups were affected with cutaneous ADRs, with a higher incidence in age group between 31 and 40 years, non-steroidal anti-inflammatory drugs (NSAIDs) (41.66%) were most commonly observed drug, followed by anti-microbials (25%) and anti-convulsants (21.66%). Fixed drug eruptions (FDE) (46.66%) most commonly observed cutaneous reaction, followed by SJS (16.66%), erythema multiformae (16.66%) most commonly observed ADRs.Conclusions: ADRs are potentially avoidable causes for seeking medical care. FDE was most common ADR and NSAIDs were most common causative agents in our study. ADRs can be prevented by avoiding polypharmacy, obtaining history of any previous skin reaction and the causative agent