Changing three crops pattern to four crops can play a potential role for achieving countries food security. With this view to increase crop productivity, production efficiency, land use efficiency, and economic return through intensifying cropping intensity as well as crop diversity by transforming three crops pattern to four crops, the experiment was conducted in High Ganges River Floodplain Soils under the Agro-Ecological Zone (AEZ) 11 at Pali, Durgapur, under the Multilocation Testing Site, Puthia, Rajshahi, for two consecutive years 2014-15 and 2015-16. Four crops pattern mustard-onion/maize-T. Aman rice was tested at on-farm condition over the existing three crops pattern mustard-onion-T. Aman rice. Maize was introduced here as a relay crop with onion to fit it in the four crops pattern. e experiment was laid out in RCB design with six dispersed replications. Two-year crop cycles were completed, and data regarding component crops yield were considered for assessing the performance of the two cropping patterns for making a sense of comparing productivity. Although there was no significant difference in component crops yield between four crops and three crops pattern, as an additional crop, maize tremendously increased the system productivity and economic return of the four crops pattern. Higher rice equivalent yield 28.96 t·ha −1 in 2013-14 and 30.95 t·ha −1 in 2014-15 was recorded from the four crops pattern with a mean rice equivalent yield (REY) 29.95 t·ha −1 over the existing pattern with a mean value 21.76 t·ha −1 . However, four crops pattern resulted in higher cultivation cost due to growing maize as an additional crop; nevertheless, it gave the higher gross return, marginal return, marginal benefit cost ratio, and production efficiency. e four crops pattern resulted averagely 37.63% higher production (REY) compared to the existing three crops pattern. Production as well as land use efficiency were increased by 9.33% and 19.18%, respectively, from the intensified alternate pattern.

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The bit error rate (BER) performance of direct sequence optical code division multiple access with cascaded optical amplifiers is analytically investigated in presence of fiber group velocity dispersion (GVD) and self phase modulation (SPM). Super Gaussian-shaped optical orthogonal codes are employed as address sequence for intensity modulation direct detection technique. The signal to noise power ratio for the proposed system is calculated on account of receiver, optical amplifier, and multiuser access interference noises. The  system performance is determined as a function of optical signal power, code length, code weight, number of simultaneous users, fiber length, and order of Super Gaussian. The power penalty suffered by the system is evaluated at BER of 10-9. The numerical results show that the BER performance of the proposed system is

highly dependent on the input signal power, bit rate, fiber length, and shape of the chip. It is found that the performance of the proposed system can be improved significantly in   presence of GVD and SPM using Gaussian shaped chip.

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In this paper, impact of polarization mode dispersion (PMD) on the bit error rate (BER) performance of direct sequence optical code division multiple access with in-line optical amplifiers is analytically investigated. Intensity modulation direct detection technique is employed in optical correlator receiver. Optical orthogonal codes are used as address sequence. The system BER performance is determined in presence of PMD and different noises induced from receiver, optical amplifiers, and multiple access interference. The power penalty suffered by the system is evaluated at BER of 10^-9. It is found that the BER performance of the proposed system degraded more at high chip rate, chirp parameter and long fiber length due to the effect of PMD. Further, the BER performance of the proposed system is studied in presence of PMD compensation with frequency advanced higher order PMD vectors. The results demonstrate that the system BER performance is improved significantly for a particular fiber length and third-order PMD compensation technique shows better performance compared to first-, and second-order compensations.

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The key concern of this paper is to bring forth a contemporary estimation of the impact of the ongoing COVID-19 pandemic on remittance inflows in Bangladesh as well as to find out the scenario of whether the migration and exchange rate have impacted on the remittance inflows in Bangladesh based on the monthly data from January 2008 to December 2021. By introducing dummy variable in the Autoregressive Distributed Lag (ARDL) bound testing approach, it is found that the ongoing COVID-19 pandemic has a strong positive impact on the remittance inflows in Bangladesh in the long-run. Besides, there is a positive impact of exchange rate on remittance inflows in the long-run while a negative relationship between the remittance inflows and migration in the long-run in Bangladesh. For the healthiness of the model, various diagnostic tests along with normality and stability test were performed over the period.