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Subsidence monitoring and analysis is an integral part of longwall operation. It provides an assessment of the effect of mining on the surface. In this study, subsidence data is recorded periodically over a longwall panel of 250m of face length and 2333m of gate roadway length for a duration of 12 months. The working seam is inclined at 10 degrees (1 in 5.5) towards tailgate side. Based on the measured data, a profile function is derived indicating vertical ground movement over the major section of the longwall panel. The bed separation of layers in the roof rock is also measured by installing Multi-Point Borehole Extensometer (MPBX) at the centre of the longwall panel and its results are correlated with those of subsidence monitored data. It is found from the analysis of subsidence and MPBX data that there is a good correlation between the bed separation sequence and the subsidence over longwall panel.

This paper aimed at the detection of wormhole attack and proposed a new method called as Neighbour Node Ratio Adhoc On demand Distance Vector Routing (NNR-AODV). NNR-AODV is an extended version of the traditional AODV routing protocol. The proposed NNR-AODV calculates the neighbour node count for every node and based on that it will decide whether the wormhole is present or not. Furthermore, NNR-AODV is able to detect both external and internal wormhole attacked nodes. Also, NNR-AODV derived a Neighbor node Threshold value which is based on the cumulative distances between nodes present in the wormhole attack. For experimental validation, we have accomplished an extensive simulation and the performance is measured through Number of bogus links, Detection rate, False positive Rate, Packet delivery ratio and Packet loss ratio. The obtained results have shown superior performance in the detection of wormhole attacks than the existing methods.

This paper aimed at the detection of blackhole attacks and proposed a new method called as Secure and Light Weight Adhoc On demand Distance Vector Routing (SLW-AODV). SLW-AODV is an extended version of the traditional AODV routing protocol. The proposed SLW-AODV ensures resilience for both blackhole and cooperative blackhole attacks. It employs a simple Challenge, Response and Confirm (CRC) strategy with chaotic maps for the identification of both blackhole and cooperative blackhole attacks. SLW-AODV identifies the attacked nodes at both route discovery and data forwarding process. For experimental validation, we have conducted extensive simulations and the performance is validated through Packet Delivery Ratio, Throughput and Average end-to-end delay. The obtained performance metrics shows an outstanding performance than the state-of-the art methods.

This work proposes a simple and effective Intrusion Detection System (IDS) to classify different attacks in MANETs. IDS extracts four features for every traffic pattern and applies Support Vector Machine algorithm over them for the classification. Before applying the feature extraction, the input traffic pattern is subjected to pre-processing as it is composed of non-uniform features. IDS classifies the input traffic pattern into three classes; they are normal, blackhole and wormhole. Finally, this work analyses the feasibility of machine learning algorithms for the detection of security attacks in MANETs. For experimental validation, we have referred a self-created dataset which was acquired from the observations of blackhole and wormhole attacked node’s traffic patterns. Moreover, we have also validated the proposed method through NSL-KDD dataset.

Alopecia areata is a chronic hair loss disorder that involves autoimmune disruption of hair follicles by CD8+ T cells. Most patients present with patchy hair loss on the scalp that improves spontaneously or with topical and intralesional steroids, topical minoxidil, or topical immunotherapy. However, recurrence of hair loss is common, and patients with extensive disease may require treatment with oral corticosteroids or oral Janus kinase (JAK) inhibitors, both of which may cause systemic toxicities with long-term use. Itaconate is an endogenous molecule synthesized in macrophages that exerts anti-inflammatory effects. To investigate the use of itaconate derivatives for treating alopecia areata, we designed a prodrug of 4-methyl itaconate (4-MI), termed SCD-153, with increased lipophilicity compared to 4-MI (CLogP 1.159 vs. 0.1442) to enhance skin and cell penetration. Topical SCD-153 formed 4-MI upon penetrating the stratum corneum in C57BL/6 mice and showed low systemic absorption. When added to human epidermal keratinocytes stimulated with polyinosinic-polycytidylic acid (poly I:C) or interferon (IFN)γ, SCD-153 significantly attenuated poly I:C-induced interleukin (IL)-6, Toll-like receptor 3, IL-1β, and IFNβ expression, as well as IFNγ-induced IL-6 expression. Topical application of SCD-153 to C57BL/6 mice in the resting (telogen) phase of the hair cycle induced significant hair growth that was statistically superior to vehicle (dimethyl sulfoxide), the less cell-permeable itaconate analogues 4-MI and dimethyl itaconate, and the JAK inhibitor tofacitinib. Our results suggest that SCD-153 is a promising topical candidate for treating alopecia areata.

Inconel 718 samples were printed with varying scan speed and laser power with volume energy density (VED) in the range of 52 J/mm3 to 75 J/mm3. Samples were then subjected to solution treatment and aging as per standards. Further, samples were characterized for their microstructure and metallurgical defects using optical microscopy (OM) and scanning electron microscopy. OM revealed that columnar grains had grown epitaxially in the build direction and grain size varies from bottom to top. Microscopic analysis on the XY plane (laser focusing plane) and the XZ plane (the plane in build direction) had revealed the presence of defects like metallurgical pores, interlayer cracks, open pores, lack of fusion, balling defects and their different morphologies. The process parameters such as scan speed, laser power and VED have influenced the porosity % and pore density and their distribution in the printed material. The microstructures also revealed the presence of oxides of Cr, Nb, Ti, Al and Fe which were identified near the interlayer cracks, large open pores and clusters of pores. Microhardness measurements of the printed samples were higher than the wrought Inconel 718 by 15-18%, both in the solution treated and aged conditions. The microhardness survey along the XY and XZ planes yielded different values even after double aging heat treatment. Average microhardness on the XZ plane was 15-20% more than that on the XY plane in each sample pertaining to the difference in grain morphology on the two planes. This difference in the microhardness values was less for the sample of high VED. The results suggest that VED in the range of 65 J/mm3 to 70 J/mm3 with scan speed and laser power between 860 mm/s to 970 mm/s and 260 W to 300 W, respectively, result in samples with tolerable microscopic defects.

In the present study, detailed metallurgical characterization was carried out on 3D-printed samples in as-printed and heat-treated conditions to understand the effect of scan speed and laser power on the microstructures, phases, types of defects, distribution of defects and oxides associated with defects. Extensive microstructural analysis was carried out using various analytical techniques such as optical microscopy, scanning and transmission electron microscopy and x-ray diffraction to establish a correlation between the microstructure phases and defects in the as-printed and heat-treated samples. A grain size study on heat-treated samples revealed that the grain size of columnar grains has increased with an increase in volume energy density (VED). The generation of different types of defects was correlated to the VED used to print samples. The optimum process parameters based on the analysis of defects through optical microscopy are: v = 860–960 mm/s; P = 250–300 W; VED = 65–70 J/mm3. Based on detailed microscopic analysis, it was noted that the heat treatment as per AMS5664 was inadequate and needs to be optimized for 3D printed IN718 samples due to incomplete dissolution of segregated Nb and Mo, carbides, oxides into the matrix during solution treatment.

M300 maraging steel was fabricated by selective laser melting (SLM), and the effect of heat treatments on the corrosion and stress corrosion resistance of the alloy was evaluated in 3.5% NaCl solution. The microstructure of the alloy in the solution-treated and aged condition is typical of lath martensitic structure along with metallurgical defects typical of SLM-processed material. The results indicated that M300 steel processed by SLM is highly susceptible to stress corrosion cracking (SCC). The fracture morphology of the samples exhibited brittle intergranular cracking along with ductile cracking features in NaCl. HIP treatment after SLM and before solution treatment and aging improved the SCC resistance of the alloy in terms of marginal increase in elongation in NaCl solution. However, this treatment could not completely eliminate the SCC susceptibility of the maraging steel in NaCl solution. The SCC susceptibility of M300 maraging steel processed by SLM can be attributed to the presence of defects such as pores which assisted the early initiation of cracks and the resultant intergranular (IGC) failure. The defects were considerably healed by subjecting the SLM-processed alloy to HIP treatment, thus improving the SCC resistance. In addition to the reduction in pore density, the increased austenite content present in the alloy after heat treatment played significant role toward improving the corrosion resistance of the as-printed M300 steel.

The purpose of the present work is to study the mechanical behaviour of AA2219-T87 friction stir weld (FSW) joints at different temperatures (Room temperature (RT), 77 K and 20 K) and correlate them to the microstructures evolved during the joining process. For this purpose, standard full length tensile specimens as well as miniature tensile specimens extracted from different microstructural regions of the joint such as weld nugget zone (WNZ), thermo-mechanically affected zone (TMAZ) and heat-affected zone were used. Similarly, fracture toughness (FT) was evaluated by placing notches at the three microstructurally different regions. The tensile properties at 77 K and 20 K were higher compared to those at room temperature. Miniature tensile specimens extracted from WNZ and TMAZ regions showed similar strength properties; however lower hardness and ductility were observed in TMAZ. Failure of standard full length samples was always in TMAZ since it has lower hardness and ductility, as a result of strain hardening. The higher FT noticed in WNZ is attributed to the presence of very fine grains. The lower FT observed in the TMAZ is attributed to combined effect of the absence of strengthening precipitates and recrystallization. Comparison of the mechanical properties of AA2219-T87 FSW and TIG weld joints revealed superior tensile properties at room and cryogenic temperatures for FSW weld joints, thus making FSW, a better alternative for the fabrication of large sized earth storable and cryogenic propellant tanks of satellite launch vehicles.

18Ni-2000 MPa maraging steel (M300 grade) is extensively used for performance critical aerospace applications where strength-toughness balance is the basis for material selection. The key to achieve the desired mechanical properties in the final product is to process the material under conditions that will impart an equiaxed, fine grained microstructure. This in turn is controlled by the selected deformation processing conditions such as strain, strain rate and temperature. Therefore, hot deformation behavior of the material is usually studied under wide temperature, and strain rate ranges to map the microstructural evolution with specimens deformed to a given strain. However, the effect of strain on the microstructural evolution, its effect on the initiation and termination of dynamic recrystallization are essential to obtain balanced mechanical properties. In this study, analysis of stress-strain curves was conducted with an intention to obtain fine prior austenite grain (PAG) size through dynamic recrystallization (DRX), and the same was verified experimentally from the microstructures evolved through hot isothermal compression tests on cylindrical specimens subjected to different strains. A single peak type DRX curve was identified for analysis from the high temperature stress-strain curves. The theoretically determined critical strain was used to experimentally verify the initiation of DRX (DRXI) and transition from DRX dominant region to grain growth dominant region (DRXT). Hot isothermal compression tests have been conducted at T=1100°C and e = 0.1s−1 and obtained PAG size of 7.68 µm in the specimen deformed to theoretically determined optimum strain of 0.6, thereby validating the used models.

XH 67 is a nickel-based superalloy, which is used in critical parts of modern aerospace engines. In the present study, XH 67 specimens in five different heat treatment conditions selected based on the processing and application have been investigated for their microstructures, morphology, and composition of the matrix and second-phase particles. Optical microscopic (OM) analysis revealed the presence of bi-model neck-lace type grains and equiaxed grains as a result of different heat treatment conditions. Scanning electron microscopy (SEM) and elemental composition analysis revealed precipitates and second-phase particles. Carbides such as Ti (N, C) and (W, Mo, Ti) C were observed having different sizes and shapes. Cr-rich carbide phases were found to be preferentially segregated along the grain boundaries. X-ray diffraction analysis was carried out for assessing the phases present in the alloy. X-ray diffraction analysis revealed the gamma matrix and the precipitate phase are crystallographically identical (coherent). Transmission electron microscopic (TEM) analysis of the specimens confirmed the presence of uniformly distributed spherical Ni3 (Al, Ti) precipitates which impart thermal stability to the superalloy. Presence of different types of carbides is also revealed by TEM analysis.