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The Duffing oscillator under time-delayed displacement feedback is investigated to study the effect of intentional time-delay on the global dynamics of the oscillator. From the free vibration study performed by employing the describing function method it is observed that for the undamped oscillator, an infinite number of limit cycles is present for all possible values of gain and delay. The number of stable and unstable limit cycles in the gain versus delay plane is studied region wise with the help of limit cycle stability lines. Secondly, in a damped system, the number of limit cycles is finite and depends upon the values of gain, delay and damping coefficient from which the maximum number of limit cycles, their frequencies and amplitudes are obtained. When the system is excited by harmonic forcing, these limit cycles exhibit the phenomena of multiple entrainments and their frequency response curves become very complex and most often results in the very high amplitude oscillations. The study of the forced damped oscillator is therefore carried out by applying the method of slowly varying parameter and the frequency response curves for period-1 responses are analyzed. Further, with the a priori knowledge of possible stable and unstable limit cycles obtained by the application of semi-analytical methods, the various instability phenomena due to subharmonic and quasiperiodic responses have also been investigated by numerical simulation using Simulink in the different parametric ranges.

Background: Broccoli [Brassica oleracea (L.) var.italica plecnk.] is a cole crop with highly perishability. It is rich in vitamin, antioxidants, anticancerous compounds and health promoting chemicals. It is harvested at tender and tight bud stage due to which the deterioration rate is high because of the high respiration rate of the broccoli head. This exotic crop is becoming popular since consumers are continuously health conscious. It has a shelf life only two days in room condition. There arise a need to retain postharvest quality of broccoli to meet the consumer demand. Methods: Three different date of planting i.e 15th Sept, 30th Sept and 15th Oct, 2014 were done in two broccoli cultivar Aishwarya and Sadhana while harvestings were done in 2015 at three different stages of head diameter i.e. 12-14 cm, 14-16 cm and above 16 cm. Storage studies for biochemical changes for ascorbic acid, chlorophyll content, total soluble solids and sensory analysis were carried out in refrigerated condition. Result: On studying the interaction effects of date of planting, variety and head diameter, it was concluded that early sown broccoli i.e 15th September showed better quality with smaller head diameter in variety Aishwarya.

In the present investigation to determine the suitability of mango varieties for Jam preparation, five Malda grown mango varieties namely, Himsagar, Lakshmanbhog, Amrapali, Fazli and Kishanbhog were utilized along with assessment of storage behavior of the end product. During the period of study TSS, ascorbic acid, titratable acidity, total sugars, reducing sugars, non reducing sugars, pH, microbial count in processed product and Organoleptic evaluation were assessed from initial day of storage to 180 th day of storage. With the advancement in the length of storage interval TSS, reducing sugar and total sugar content and titratable acidity showed a gradual increase upto 180 days of storage. The overall assessment of quality revealed that with respect to conjugal study of all these parameters jam prepared from the variety Himsagar proved considerably superior. The maximum Overall acceptability score (7.79) also had been gathered by jam manufactured from Himsagar variety.

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