Search

This paper presents classification of gas bubble in a Doppler ultrasound signal using Synchrosqueezing Transform (SST). The SST decomposes the signal into a number of scales. In this research work, initially two statistical parameters, the peak value and variance are estimated to Figure out the scales that contains gas bubbles. Then the signal is reconstructed from the coefficient values within the selected scale. Some parameters are defined and calculated from the reconstructed signal. These parameters are used to classify gas bubble signal using naive Bayes classifier. However, two classes “bubble” and “not bubble” are identified by training data sets. Therefore, on the basis of posterior probability, the class of the signal is defined. Finally, performance of gas bubble detection is evaluated in terms of sensitivity and positive predictivity tests. Our proposed method is applied on grade 0, I, II, and III signals. It is observed that, good classification result is achieved in grade I and grade II. In grade 0, no gas bubble is found. In the experiment, 92% gas bubble is classified in grade I, 84% gas bubble is classified in grade II and 80% gas bubble is classified in grade III. Experimental result shows that the proposed method achieves better accuracy than the conventional method in the literature.

White rot caused by Sclerotium cepivorum fungus is a crucial soil borne disease on garlic damaging allium production globally including Bangladesh. In this study eight isolates of Sclerotium cepivorum were isolated from naturally infected garlic plants collected from the central farm and isolated in the central lab of Sher-e-Bangla Agricultural University, Dhaka, Bangladesh to determine the prevalence of white rot disease incidence and severity and characterized for cultural and morphological variabilities of the isolated pathogen. Eight garlic varieties viz. BAU Rashun-1, BAU Rashun-2, BARI Rashun-1, BARI Rashun-2, BARI Rashun-3, BARI Rashun-4, Local Deshi and Local Indian were explored with three replication in the study. Results showed that the highest disease incidence and severity against white rot disease (33.33% and 89.33%) were appeared in the BARI Rashun-3 variety. Lowest disease incidence and severity (5.00% and 60%) were recorded on Local Indian variety. Almost all of the isolates had cottony fluffy growth on potato dextrose agar. The colony color varied from milky white to cottony watery white with regular, circular, smooth, cotton like sometimes striped surface texture was found. After 10 days of incubation all the isolates had suppressed growth on PDA media as it is a fast growing pathogen.