Reduced stiffness buckling of sandwich cylindrical shells under uniform external pressure

A reduced stiffness lower bound method for the buckling of laterally pressure loaded sandwich cylindrical shell is proposed. Also, an attempt is made to assess the validity of the proposed reduced stiffness lower bound with FEM numerical examples. In addition, the proposed method is compared with classical and Plantema's approaches of the buckling of the laterally pressure loaded sandwich cylindrical shell. Comparison of the proposed reduced stiffness lower bound with that obtained from non-linear FEM analysis verifies that it indeed provides a safe lower bound to the buckling of laterally pressure loaded sandwich cylindrical shells. The attractive feature of the proposed reduced stiffness method is that it can be readily used in designing laterally pressure loaded sandwich cylindrical shells without being concerned about geometrical imperfections.     

Effect of nanoparticle nature on hydrogen concentration profiles and improved switching characteristics in Gd switchable mirrors

A detailed elastic recoil detection analysis using 40 MeV 28Si5+ ions has been carried out to study the changes in the H concentration and concentration profiles during the hydrogenation/dehydrogenation process in polycrystalline and nanoparticle Gd layers formed using vacuum evaporation and inert gas evaporation techniques, respectively. Nanoparticle sample exhibits a larger difference in the [H]/[Gd] values (2.9 and 1.7) in comparison to polycrystalline sample (2.4 and 2.0) in the loaded and deloaded states. Hydrogenation/dehydrogenation activity is restricted to the top portion in case of polycrystalline sample. In contrast to this, size induced structural transformation; enhanced surface area and the presence of large number of inter particle boundaries due to nanoparticle character result in the complete Gd layer becoming active during switching.     

High-Performance Multifunctional Fuel Additives Derived from Renewable Fatty Acids and Phosphazene

The increasing need for high-quality diesel fuel can be fulfilled by using environmental friendly, high-performance additives. We have synthesized novel fatty acid-derived multifunctional additives coupled with phosphazene moiety having the backbone of alternative nitrogen and phosphorous atoms which provided stability, while the additives possessed affinity for the metal surface to form a surface-complex film leading to the hindered metal contact and providing friction-reducing and antiwear properties. In addition, the applicability of the synthesized additives was investigated by testing the anti-oxidant and anticorrosion properties in polyethylene glycol (PEG200) which was taken as the reference base fluid. A rotating bomb oxidation test was used to evaluate the anti-oxidant characteristics, and a four-ball test for the tribological properties. Among the synthesized additives, phosphazene ester of erucic acid exhibited the best antiwear and antifriction properties; however, phosphazene ester of oleic acid was found to be the best anti-oxidant additive.     

Eight Element Low-Cost Microstrip MIMO Antenna for Wi-MAX and 5G Applications

Wireless Personal Communications - In this communication, a low-cost four/eight-element MIMO antenna is proposed for Wi-MAX (IEEE 802.16d) and 5G applications band. A reverse U-shaped slot is...     

BILEAT: a highly generalized and robust approach for unified aspect-based sentiment analysis

Applied Intelligence - Aspect-based sentiment analysis (ABSA) includes two subtasks, namely, aspect term extraction and aspect-level sentiment classification. Most existing works address these...     

RePIDS: A multi tier Real-time Payload-based Intrusion Detection System

Intrusion Detection System (IDS) deals with huge amount of network traffic and uses large feature set to discriminate normal pattern and intrusive pattern. However, most of existing systems lack the ability to process data for real-time anomaly detection. In this paper, we propose a 3-Tier Iterative Feature Selection Engine (IFSEng) for feature subspace selection. Principal Component Analysis (PCA) technique is used for the pre-processing of data. Mahalanobis Distance Map (MDM) is used to discover hidden correlations between the features and between the packets. We also propose a novel Real-time Payload-based Intrusion Detection System (RePIDS) that integrates a 3-Tier IFSEng and the MDM approach. Mahalanobis Distance (MD) dissimilarity criterion is used to classify each packet as either a normal or an attack packet.The effectiveness of the proposed RePIDS is evaluated using DARPA 99 dataset and Georgia Institute of Technology attack dataset. The traffic for Web-based application is considered for validating our model. F-value, a criterion, is used to evaluate the detection performance of RePIDS. Experimental results show that RePIDS achieves better performance (high F-values, 0.9958 for DARPA 99 dataset and 0.976 for Georgia Institute of Technology attack dataset respectively, with only 0.85% false alarm rate) and lower computational complexity when compared against two state-of-the-art payload-based intrusion detection systems. Additionally, it has 1.3 time higher throughput in comparison with real scenario of medium sized enterprise network.     

热压成型工艺单向铺层纤维密实状态研究

针对热压成型过程,利用光学显微镜及量化统计模型,系统研究了复合材料单向铺层纤维的密实状态,提出了纤维理论密实值和工程密实值的表征参数hL、hG.利用纤维密实值可以预测达到所需纤维体积分数时的工艺压力,为优化热压成型工艺窗口和短程流动模型的建立提供了重要的实验依据.     

Exopolymer produced by Pseudomonas aeruginosa: A super sorbent for ruthenium

Pseudomonas aeruginosa exopolymer was found to have a sorption capacity of 196.3 mg/g at 100 µg/mL of ruthenium, pH 2.8, and 30 min, which is 5–10 times higher compared to the earlier reports. Uptake mechanism was deduced using sorption studies and energy-dispersive X-ray fluorescence, proton-induced X-ray emission, scanning electron microscopy, and Fourier transform infrared spectroscopy techniques. Shrinking and volume change were observed in the morphology of the exopolymer upon ruthenium uptake. During biosorption, occurrence of ion exchange and involvement of carboxyl, ether, and alcoholic functional groups were noted. Biopolymer was found to be a potential sorbent for soluble radionuclide removal during nuclear fuel reprocessing and hazardous waste disposal.     

Study of thermal,flammability and mechanical properties of intumescent flame retardant PP/kenaf nanocomposites

Detrimental physical and mechanical properties are common problems for composites when their flame retardancy is improved through filler additions. An increased interest of the synergistic nanoparticle addition to improve the flame retardancy of natural fiber composites is the aim of this work. The paper investigates the synergistic effect of two different nanoparticles (halloysite nanotubes (HNTs) and montmorillonite (MMT) nanoclay) on the flame and mechanical properties in an intumescent ammonium polyphosphate (APP)-based polypropylene (PP)/kenaf composite system. First, the nature of nanoparticle dispersion in PP through X-ray diffraction (XRD) and transmission electron microscopy (TEM) reveals that under twin screw compounding process, the partial exfoliation and intercalation have taken place within the nanocomposites. An increase in the decomposition temperature was observed under thermogravimetric analysis (TGA), with the presence of HNT. However, MMT tends to lower the maximum decomposition temperature under inert atmosphere. The flammability analysis in an intumescent flame retardant (IFR) system shows that the suitable amount of high aspect ratio nanoparticles with their exfoliation characteristics effectively helps to reduce the sustained combustion. Even though, improved stiffness properties can be observed with the presence of increased filler content, particle agglomeration tends to reduce the mechanical strengths of these composites due to low compatibilization and crack propagation.     

Enhanced mechanical properties of acrylate based shape memory polymer using grafted hydroxyapatite

In the present study, the effect of grafted and ungrafted hydroxyapatite (HAp) filler on the mechanical properties of acrylate based shape memory polymer (SMP) composite is reported. HAp is grafted with polyethylene glycol methacrylate (PEGMA) monomer to avoid agglomeration and the same is embedded as reinforcement in tBA – PEGDMA matrix (70 wt% tBA: tert-butyl acrylate +30 wt% PEGDMA: polyethylene glycol dimethacrylate). The grafting process improved the interfacial interactions of the particles, dispersed in the polymer system and subsequently enhanced the mechanical properties of the shape memory polymer composites. The morphology of HAp particles is investigated by field emission scanning electron microscopy. The mechanical properties of SMP composites are evaluated at room temperature and above glass transition temperature (Tg) with grafted and ungrafted HAp particles. The addition of grafted HAp significantly improved the tensile strength (40%) and shape recovery rate (25%) of the SMP composite when compared to the SMP composite containing ungrafted HAp. SMP composite containing grafted HAp exhibited higher cell viability compared to the neat SMP and the SMP composite containing ungrafted HAp.