Future Armour Materials and Technologies for Combat Platforms

The ultimate goal of armour research is to create better armour for battle worthy combat plat forms such as main battle tanks, infantry combat vehicles and light combat vehicles. In each of these applications, the main aim boils down to one of the two things; either reduce the weight without sacrificing protection or enhance the performance at same or even reduced weight. In practice, these ambitions can be fulfilled only if we have with us, appropriate improved armour materials, advanced and innovative technologies and also improved designs, which enable us to use them for creating next generation armour modules. Armour systems have progressed through improvements in metallic, ceramic and lightweight (low areal density) composite materials. Similarly, the advances in development of explosive reactive armour (ERA) and non-explosive reactive armour (NERA) have generated efficient armour system against contemporary high explosive antitank ammunition and missile threats for the armoured vehicles. Yet, to achieve armour performance exceeding that of the current light combat vehicles and main battle tanks, further advancements in armour materials, systems, and survivability technologies are required for new vehicular systems that weigh significantly less than the present combat platforms. Various approaches and advancements in the metallic and composite armour materials, ERA and NERA systems to improve the survivability of armoured vehicles in the futuristic multi-spectral battlefield scenarios are described

Influence of Polymer Restraint on Ballistic Performanceof Alumina Ceramic Tiles

An experimental study has been carried out to evaluate the influence of confinement ofalumina ceramic tiles through polymer restraint, on its ballistic performance. Tiles of 99.5 per centpurity alumina were subjected to ballistic impact against 7.62 mm armour piercing projectiles atvelocities of about 820 m/s. The tiles of size 75 mm x 75 mm x 7 mm were confined on both facesby effectively bonding varying numbers of layers of polymer fabrics. These were then bondedto a 10 mm thick fibre glass laminate as a backing using epoxy resin. High performance polyethyleneand aramid polymer fabrics were used in the current set of experiments for restraining the tiles.Comparative effects of confinement on energy absorption of tiles with varied number of layersof fabrics were evaluated. It was observed that by providing effective confinement to the tile,energy absorption could be doubled with increase in areal density by about 13 per cent.Photographs of the damage and the effects of restraint on improvement in energy absorptionof ceramic tiles are presented and discussed

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Not AvailableStudies on variability and spatial dependence of some physical and chemical soil properties in fluecured tobacco fields conducted at northern light soil farm, CTRI Research Station, Jeelugumilli during 1997-2000 revealed that standard deviation of soil pH was small in relation to the estimated mean. Values of standard deviation of organic C and soil-water retained at different matric suctions were medium while those of EC, Cl, available P and available K were very high in both soil layers. Normal distribution of soil properties over the entire farm was significant at 0.05 level with respect to soil pH in surface layer and available K in subsurface layer. Some soil properties followed normal distribution in some individual blocks. Values of EC did not follow normal distribution in any block. These results indicated high degree of variability of soil properties within blocks in both soil layers. The parameters were grouped according to the relative amounts of variability. In the lowest class was soil pH with a CV of about 10-11%. On the other hand were four parameters viz., EC, Cl, available P and available K, which were more variable, each with a CV greater than 42%. Variations for soilwater retained at different matric suctions and organic C were intermediate. Spectacular differences in CV values were not obtained between blocks for all soil properties studied except for a few differences in CV values of some properties. Very few numbers of samples are needed to estimate soil pH than the other parameters. Only 5 samples are required to estimate mean within 10% of true mean at 0.05 significance level. Soil-water retained at different matric suctions and organic C require about 31 to 52 samples whereas EC, Cl, available P and available K require 66 to 203 samples to estimate mean within 10% of true mean at 0.05 significance level. Autocorrelation function for different soil properties indicated spatial dependence of soil available P and available K up to 4 m and weak autocorrelation for Cl and organic C.Not Availabl

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Not AvailableField experiment was conducted during post rainy seasons of 2007-08 and 2008-09 at ICAR-CTRI RS, Jeelugumilli, Andhra Pradesh to study the influence of nitrogen and potassium doses and topping levels on yield, and quality of FCV tobacco CMS hybrid line CH-3. Application of 115 and 130 kg N/ha increased the mean yields of green leaf by 1809 (14.56) and 3058 (24.62), of cured leaf by 228 (10.41) and 360 (16.43), and of grade index by 106 (6.61) and 155 kg/ha (9.87%), respectively compared with that of 100 kg N/ha. Application of 135 and 150 kg K2O/ha increased the mean yields of green leaf by 1588 (12.64) and 2847 (22.66), of cured leaf by 177 (7.95) and 305 (13.7), and of grade index by 64 (3.94) and 127 kg/ha (7.82%), respectively compared with that of 120 kg K2O /ha. Topping at 26 leaves recorded significantly higher green leaf by 384 (2.77), cured leaf by 85 (3.63) and grade index by 84 kg/ha (5.1%) when compared to that of 24 leaves topping level. The leaf chemical quality parameters viz. nicotine, reducing sugars, and reducing sugars/nicotine ratio showed changes in response to N and K rates and topping levels and were within the acceptable limits. The total N uptake in 100 kg N/ha was 74.14 kg/ha, while it was 89.36 kg/ha with 130 kg N/ha. Of the mean total 82.18 kg/ha N uptake, proportion of N accumulation in stem, root, lamina, and midrib was 21.15, 19.43, 43.85 and 15.56%, respectively. Total K uptake with 120 kg K2O/ha was 132.22, while it was 152.22 kg/ ha with 150 kg K2O/ha. Of the total 142.63 kg/ha K uptake, proportion of K accumulation in stem, root, lamina, and midrib was 24.4, 10.0, 33.0 and 32.6% respectively. N, P and K uptake in stem, root, lamina, midrib and total was not affected by topping levels. It can be concluded that application of 130 kg N/ha and 150 kg K2O/ha and topping at 26 leaves is essential to get higher productivity, better quality and nutrient uptake for the CMS hybrid CH 3.Not Availabl

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Not AvailableQuantity-Intensity parameters of potassium were studied in Flue–cured Virginia tobacco soils by analyzing twenty eight soil samples (0-9") collected from Southern Light Soils (SLS) and Southern Black Soils (SBS) areas of Prakasam and Nellore districts. Textural variation in black soils was silty clay loam to clay whereas in light soils it was sandy loam to clay loam. Soils from SLS and SBS were neutral in soil reaction and low in EC, chlorides and organic carbon. Southern black soils have higher pH, EC, chlorides and organic carbon compared to SLS. Water soluble-K was more in SLS whereas exchangeable K, non-exchangeable-K, total-K and lattice-K were high in SBS which was due to higher clay content and potassium bearing minerals in black soils compared to light soils of Prakasam and Nellore districts. Equilibrium activity ratio ARKo values were high in SLS compared to SBS hence SLS area have more readily available potassium. The ranges for PBCK in SBS and SLS were 80.3 200 and 7.3 – 126.4 c mol (p+)/kg, respectively. PBCK values were more in SBS compared to SLS because of more clay content in SBS (23.8 to 47.4%) compared to SLS (9.43 to 35.64%), which shows that they have more replenishing capacity. Potassium on specific sites (KX) and on non-specific sites (KO) were high in soils of SBS area compared to SLS which is a measure of quantity parameter. Equilibrium activity ratio (ARKo) values were positively correlated with sand, whereas significant positive correlation was observed between PBCK, KO, KX, and KL and silt and clay contents. Water solubleK showed significant positive correlation with ARKo, whereas, exchangeable-K showed significant positive correlation with PBCK , KO , KX, and KL.Not Availabl

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Not AvailableField experiment was conducted for two consecutive seasons (2004-05 and 2005-06) to study the influence of foliar spray and topping level on yield and quality of FCV tobacco cv. Kanchan proved that two foliar sprays of 0.5% Zn SO4 + 0.5% Mg SO4 at 35 and 45 days after planting enhanced mean green leaf yield, cured leaf yield and grade index by 2303.5 (15.7%), 116 (5.1%) and 236.5 kg/ ha (14.77%) respectively as compared to two water sprays. Topping at 24 and 28 leaves both being on a par enhanced mean green leaf yield by 2649 (18.6%) and 2701 kg/ha (19.0%), cured leaf yield by 500 (24.8%) and 529 kg/ha (26.3%), and that of grade index by 489 (35.1%) and 519 kg/ha (37.2%), respectively as compared to 16 leaves topping level. Foliar sprays of 0.5% Zn SO4 + 0.5% Mg SO4 recorded significantly higher reducing sugars in P and X positions in both the seasons and higher nicotine in P, X, L and T positions during 2004-05 and in P and X positions only during 200506 as compared to other foliar sprays. Topping at 28 leaves level recorded significantly lower reducing sugars and nicotine content and there was a significant increase in reducing sugars and nicotine content as the topping level decreased from 28 to 16 leaves. Chlorides were well within the acceptable limits of good quality. It can be concluded that two foliar sprays of ZnSO4 + Mg SO4 at 35 and 45 days after planting and topping at 24 or 28 leaves would be optimum for the cv. Kanchan for getting higher green leaf yield, cured leaf yield and grade index with superior quality in irrigated Alfisols of Andhra Pradesh.Not Availabl

Radiation grafted poly(vinylidene fluoride)-graftpolystyrene sulfonic acid membranes for fuel cells: Structure-property relationships

Structure-property relationships for poly(vinylidene fluoride)-graft-polystyrene sulfonic acid (PVDF-g-PSSA) fuel cell membranes prepared by a single step method involving radiation-induced grafting of sodium styrene sulfonate (SSS) onto electron beam (EB) irradiated poly(vinylidene fluoride) (PVDF) films were established. The physico-chemical properties of the membranes such as ion exchange capacity, water swelling and proton conductivity were correlated with the degree of grafting (G, %) and the structural changes taking place in the membrane matrix during the preparation procedure. The variation in the crystallinity and the thermal stability of membranes was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. The membranes were found to undergo substantial structural changes in forms of ionic sites increase, hydrophilicity enhancement, hydrophobicity reduction and crystallinity decrease with the variation in G (%) and the preparation method. The structural and thermal properties of the obtained membranes were also compared with their counterparts prepared by a conventional two-steps method i.e. radiation induced grafting of styrene onto EB irradiated PVDF films followed by sulfonation. The PVDF-g-PSSA membranes obtained by a single-step method were found to have superior properties compared to those obtained by the conventional two-steps method

Domains and domain dynamics in fluorite-structured ferroelectrics

Ferroelectricity in fluorite-structured ferroelectrics such as HfO2 and ZrO2 has been attracting increasing interest since its first publication in 2011. Fluorite-structured ferroelectrics are considered to be promising for semiconductor devices because of their compatibility with the complementary metal-oxide-semiconductor technology and scalability for highly dense information storage. The research on fluorite-structured ferroelectrics during the first decade of their conceptualization has been mainly focused on elucidating the origin of their ferroelectricity and improving the performance of electronic devices based on such ferroelectrics. Furthermore, as is known, to achieve optimal performance, the emerging biomimicking electronic devices as well as conventional semiconductor devices based on the classical von Neumann architecture require high operating speed, sufficient reliability, and multilevel data storage. Nanoscale electronic devices with fluorite-structured ferroelectrics serve as candidates for these device systems and, thus, have been intensively studied primarily because in ferroelectric materials the switching speed, reliability, and multilevel polarizability are known to be strongly correlated with the domains and domain dynamics. Although there have been important theoretical and experimental studies related to domains and domain dynamics in fluorite-structured ferroelectrics, they are yet to be comprehensively reviewed. Therefore, to provide a strong foundation for research in this field, herein, domains, domain dynamics, and emerging applications, particularly in neuromorphic computing, of fluorite-structured ferroelectrics are comprehensively reviewed based on the existing literature. © 2021 Author(s).N

Worked and decorated shell discs from southern Arabia and the wider Near East

This article presents and discusses a corpus of worked and decorated shell discs from recently excavated archaeological sites in southern Arabia, including Dibba (northern Oman), Saruq al-Hadid (UAE) and Sumhuram/Khor Rori (southern Oman). The artefacts are compared to a wide range of shell discs from controlled excavations in Arabia and the broader Near East in order to better understand their date, manufacture and use. The comparative study highlights the wide distribution of decorated shell discs across the ancient Near East, particularly during the early Iron Age, and the complex economic and cultural connections that underpinned the collection, crafting, exchange and significance of such items