Infra-red decoy flares constituting of Magnesium, Teflon and Viton or MTV, is the most widely acceptable off-board counter measures among majority of the defence forces across the world. These flares ...are essentially pyrotechnic compositions operating in the range of 3–5µm wavelength owing to the selective emission of the combustion products (MgO, MgF
2
and oxides of carbon namely CO and CO
2
). However, literature on manufacturing techniques and performance characteristics of standard configurations flare pellets developed and supplied by few firms globally is somewhat restricted. Hence, this study is an attempt to evaluate the performance of mechanically pressed 50 mm diameter cylindrical MTV pellets. While varying the process parameters viz. charge mass and applied load for pelleting, the cross-sectional area of the pellets and dwell time of applied load have been maintained constant. With increase in applied load, elastic/brittle fracture of the particles occur which increases surface area of contacts between particles. The optimum density was achieved at 8 tons of load. Similarly, the improvement in density with increase in charge mass was observed till L/D ratio of unity was achieved. SEM images confirmed the increase in contact surfaces and reduction in size of particles owing to elastic/brittle fracture. With increase in applied load, the available surface area decreased and there was a conspicuous increase in burn time. With increase in charge mass, the quantity of pyrotechnic mixture available for burning increased leading to increase in burn time.
Magnesium/Teflon/Viton or MTV based pyrotechnic composition has been the most preferred composition for decoy flares against conventional heat-seeking missiles for more than four decades. MTV flares ...of standard configurations are available globally but the details of their manufacturing process including compacting pressure and compressive strength of the flare pellets have not been explicitly defined. The pellets are sub-assembly of the flares dispensed in flight and are critical for successful operations of the decoy flares. Hence, in the present paper, an attempt has been made to optimize the process parameters namely charge mass (A), applied load (B) and dwell time (C) which are responsible for performance variation of compacted standard configuration cylindrical pellets of 50 mm diameter. Each of the process parameters has been considered for three levels. L
27
array has been selected to represent these parameters and their interactions. The Taguchi robust experimental method arrived at the optimal result as A1B3C3 (100 g of charge mass, 78.48 KN of applied load and 20 s of dwell time). Analysis of Variance (ANOVA) highlighted that applied load followed by charge mass significantly influenced the density of the pellets. Finally, general regression equation was derived with R
2
value of 0.936 and validated with experimental results.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Magnesium/Teflon/Viton or MTV pyrotechnic composition has been widely preferred to prepare decoy flares as countermeasures against heat seeking Infra-red (IR) missiles. Though MTV for military ...applications are available in the global market, the manufacturing process and performance characteristics of these flares have not been explicitly defined. The pellets which are an essential sub-assembly of the flares need to be extensively studied to develop these flares for military applications. The study paper attempts to optimise the density of compacted 50 mm diameter cylindrical pellets. The pyrotechnic composition is initially subjected to various sensitivity tests namely impact, friction and spark to assess the threshold values of initiation of this composition. Three levels of process parameters for pelleting have been considered and L
27
array has been selected to represent the process parameters namely charge mass (A), applied load (B), dwell time (C) and their interactions. The Taguchi robust experiment method arrived at the optimal result as A1B3C3 (100 g of charge mass, 8 tons of applied load and 20 s of dwell time). Analysis of Variance (ANOVA) highlighted that parameters A and B significantly influenced the density of the pellets. Finally, general regression equation was derived with R
2
value of 0.94.
The fall armyworm (FAW),
, is one of the most devastating invasive polyphagous pests, which has attracted recent global attention by developing resistance to various insecticidal active ingredients ...with independent mode of action. Fluxametamide, a newly commercialized isoxazoline insecticide, is exceptionally selective towards several lepidopteran pests. The present study aimed to evaluate resistance risk in FAW to fluxametamide and the fitness costs associated with fluxametamide resistance. A field-collected and genetically mixed population of FAW was artificially selected through continuous exposure to fluxametamide. After successive selection of 10 generations, there was no obvious increase in the LC
(RF: 2.63-fold). The realized heritability (
) of fluxametamide resistance was estimated as
= 0.084 using a quantitative genetic approach. Compared with the susceptible F0 strain, the Flux-SEL (F10) strain of FAW displayed no significant cross-resistance to broflanilide, chlorantraniliprole, fipronil, indoxacarb, lambda cyhalothrin, spinetoram, and tetraniliprole, except emamectin benzoate (RF: 2.08-fold). Increased activity of glutathione
-transferase (ratio 1.94) was observed in the Flux-SEL (F10) strain of FAW, while the cytochrome P450 and carboxylesterase activities were not altered. The fluxametamide-selection significantly affected the development and reproductive traits of FAW with a lower
,
and relative fitness (
= 0.353). The results alluded that the risk of fluxametamide resistance evolution in FAW is relatively lower; however, proactive implementation of resistance management approaches should be done to maintain the field efficacy of fluxametamide against FAW.
Facing cold stress is amajor constraint in seedling production during the winter season as, most particularly in recent times due to uncertain climatic conditions, no sustainable technology has been ...reported that could be easily adopted by farmers withlimited resources. Therefore, field experiments were carried out during winter 2017–2018 and 2018–2019 at the Central Research Farm of Bidhan Chandra KrishiViswavidyalaya, West Bengal, India to study the growth, survival potential, yield and nutritional and biochemical properties of boro rice seedlings as influenced by two seedbed management practices viz. conventional seedbed (farmers’ practice) and improved seedbed (polythene protected with micronutrient supplementation). The major objective was to lower the nurserybed duration without compromising seedlings’ health and to studythe economic viability during the winter season. The experiment was laid out in ten experimental units and deployed anindependent-sample t-test to compare the performance of the seedlings. The microclimatic changes were also itemized from both seedbeds. The seeds sownunder improved nursery conditions resulted in better seedling emergence (~90%) and survival percentage (~85%) as compared to the conventional seedbed (~70% and 65%). Growth attributes in terms of plant height, biomass accumulation, root characteristics, tiller count, and growth rate were observed to be better from the polythene-protected nursery bed. Theimproved nursery bed accounted for 20% higher seedling count at the time of transplantation over the conventional bed. The microclimatic situation under a polythene covering was also favorable for germination and seedling growth. Maximum nutrient (N, P, and K) concentrations, as well as chlorophyll content, wererecorded from improved seedlings. Results suggested that the improved seedbed management was apotential alternative toearly embolden seedling production during the winter to avoid climatic abnormalities. Most importantly, improved seedbeds ensured a comprehensive route from germination to healthy seedling production without any failure in thesmalltime window, which involvedless input as well as cost involvement. This technique could diffusethe problem oflate sowing conditions in the rice–rice cropping system.
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