Performance improvement of wireless secret key generation with colored noise for IoT

Achieving security in the Internet of things (IoT) networks by generating symmetric keys from the wireless channel parameters like received signal strength (RSS) is a promising approach. Despite the easy acquisition of the RSS signal, RSS‐based security is less explored for IoT. In this work, we analyze the performance of RSS‐based wireless physical layer key generation with correlated colored noise components and proposed a low complexity filtering approach to improve the performance for the IoT network. We started with providing a survey of various recent researches related to RSS‐based key generation and also discussed correlated colored noise components with a few of the recent works considering them. Further, we analyze various colored noise components in the time domain by the Allan variance and Ljung‐Box test. Furthermore, we develop a key generation model and proposed a moving window averaging‐based filtering followed by Lloyd max quantization to improve the BDR performance, degraded due to the presence of correlated colored noise components. The simulation results show that the proposed preprocessing technique has a considerable improvement in the BDR performance, and the keys generated have sufficient randomness, which is verified by NIST test.     

Chemometrics in Ascertaining Hydrogeochemical Characteristics of Coal Mine Discharge vis-à-vis Behaviour of Surface and Groundwater Resources of the Mahan River Catchment Area,Central India

We investigated the hydrogeochemical regime of an AMD-affected coal mining province. 98 water samples were collected over two seasons and analysed for 14 parameters. We attempted to discriminate the sources of variation of water quality using select multivariate techniques: display methods (principal component analysis) and unsupervised pattern recognition (cluster analysis). Most of the groundwater and river water were characterised by shallow freshwater facies (Ca–Mg–HCO₃ type), whereas the samples representative of mine water were of the Ca–Mg–SO₄ type. The mines of the area annually discharge 2901 t of solute loads, ranging from 91 to 1030 t/year. Various molar ratios suggest that dissolution of the silicates associated with the mixing process is the predominant solute acquisition processes that govern the water chemistry of the region besides AMD. The chemometric results indicated that only a few groundwater and river water samples had low pH and elevated total dissolved solids, and these were near the three mines that were affected by AMD. These results substantiate the effectiveness of the mine water treatment measures implemented at the mine sites.

     

Quality assessment of graphene: Continuity,uniformity, and accuracy of mobility measurements

With the increasing availability of large-area graphene,the ability to rapidly and accurately assess the quality of the electrical properties has become critically important.For practical applications,spatial variability in carrier density and carrier mobility must be controlled and minimized.We present a simple framework for assessing the quality and homogeneity of large-area graphene devices.The field effect in both exfoliated graphene devices encapsulated in hexagonal boron nitride and chemical vapor-deposited (CVD) devices was measured in dual current-voltage configurations and used to derive a single,gate-dependent effective shape factor,β,for each device.β is a sensitive indicator of spatial homogeneity that can be obtained from samples of arbitrary shape.All 50 devices investigated in this study show a variation (up to tenfold) inβ as a function of the gate bias.Finite element simulations suggest that spatial doping inhomogeneity,rather than mobility inhomogeneity,is the primary cause of the gate dependence ofβ,and that measurable variations ofβ can be caused by doping variations as small as 1010 cm-2.Our results suggest that local variations in the position of the Dirac point alter the current flow and thus the effective sample shape as a function of the gate bias.We also found that such variations lead to systematic errors in carrier mobility calculations,which can be revealed by inspecting the correspondingβ factor.     

Fabrication of Smart Tantalum Carbide MXene Quantum Dots with Intrinsic Immunomodulatory Properties for Treatment of Allograft Vasculopathy

MXene nanomaterials have sparked significant interest among interdisciplinary researchers to tackle today's medical challenges. In particular, colloidal MXene quantum dots (MQDs) offer the high specific surface area and compositional flexibility of MXene while providing improvements to aqueous stability and material–cell interactions. The current study for the first time reports the development and application of immunoengineered tantalum-carbide (Ta₄C₃T_x) MQDs for in vivo treatment of transplant vasculopathy. This report comes at a critical juncture in the field as poor long-term safety of other MXene compositions challenge the eventual clinical translatability of these materials. Using rational design and synthesis strategies, the Ta₄C₃T_x MQDs leverage the intrinsic anti-inflammatory and antiapoptotic properties of tantalum to provide a novel nanoplatform for biomedical engineering. In particular, these MQDs are synthesized with high efficiency and purity using a facile hydrofluoric acid-free protocol and are enriched with different bioactive functional groups and stable surface TaO₂ and Ta₂O₅. Furthermore, MQDs are spontaneously uptaken into antigen-presenting endothelial cells and alter surface receptor expression to reduce their activation of allogeneic T-lymphocytes. Finally, when applied in vivo, Ta₄C₃T_x MQDs ameliorate the cellular and structural changes of early allograft vasculopathy. These findings highlight the robust potential of tailored Ta₄C₃T_x MQDs for future applications in medicine.     

Analysis of Frequent Failure of Oil Well Tubings Due to Formation of Longitudinal Slit

In an onshore oil field, many premature tubing failures were observed in wells operating on sucker rod pump. Failures were in the form of longitudinal crack/vertical slit. During last three to four years, the failure frequency had increased and in one well, new tubing vertically cracked in 8 months only. In the internal surface of the tubing, a longitudinal grooving was observed. The shape of the groove resembled the sucker rod and the crack was along the groove. Observation of grooved region under SEM revealed abrasion features typical of mechanical wear. Small corrosion pits were also observed on some portion of grooved region. As the well was vertical, so chance of contact between tubing and sucker rod was low. But tubing was freely suspended in the well, i.e., there was no tubing anchor which made it vulnerable for the buckling. Analytical studies showed that the failed tubing was in buckling region. On comparison of hardness, it was observed that tubing material was softer than the sucker rod. Buckling of the tubing resulted in rubbing of sucker rod against tubing wall due to which tubing had worn out in the form of groove. Wear-oxidation and oxidation-wear of tubing surface at grooved region and corrosive agents of produced water accelerated this material removal process and when the wall thickness of the tubing at groove region reduced to a point where it was not enough to withstand the hoop stresses, a longitudinal crack formed in the grooved region and tubing failed.     

Regeneration of the limb: opinions on the reality

Whenever the topic of re-growing human limbs is posed for discussion, it is often argued that ‘if a newt can do it, then so can we’. This notion, albeit promising, is somewhat like watching a science-fiction film; the individual components are currently available but we are far from realizing the complete picture. Today’s reality is that if we are faced with a limb-severing injury, any regenerative attempt would endeavour to accelerate the pace at which the tissue heals to a clinically relevant/functional state. The science of limb regeneration can be approached from three different angles, developmental biology; regenerative medicine; and tissue engineering. This opinion piece describes how each approach can be used to understand the concepts behind regeneration, how far each approach has advanced and the hurdles faced by each of the approaches.     

Effect of initial dextrose concentration,seeding and cooling profile on the crystallization of dextrose monohydrate

A batch seeded cooling crystallizer was used to study dextrose monohydrate crystallization. Experiments were conducted to investigate how a 2% increase in the initial dextrose concentration (from 65.5 to 67.5%) would influence final crystal yield and size. The crystallizations were performed for three different seed masses and cooling profiles, consequently the influence of these parameters was also investigated. The parameters were varied in accordance with an industrial scale process. An in-line focused beam reflectance measurement probe and an in-line process refractometer were used to continuously monitor the crystallizations. The experimental results showed that the 2% increase in initial dextrose concentration had a major influence on the rate of crystallization and yield over a 24 h crystallization period, and only a minor influence on the median crystal size.     

Measurement and Control of Process using Soft Computing

Abstract

Control of process parameters is considered to be a critical problem in the process industry. The process considered for modeling is a liquid level system. The model identification and parameter selection are approximated to a First Order Plus Dead Time (FOPDT). Here, the controller design is based on a conventional Proportional–Integral (PI) controller and intelligent controller like Fuzzy Logic Controller (FLC). The objective of the current study is to design control strategies in real time using MATLAB software interfaced with Adam's data acquisition module. A comparative analysis based on FLC with a conventional controller is presented, with various time domain specifications. It is found that, under servo and regulatory changes, FLC shows an improved performance over its conventional techniques based on performance measures like peak time, settling time, overshoot, Integral Square Error (ISE) and Integral Absolute Error (IAE).     

In situ TEM study of Au–Cu alloy nanoparticle migration and coalescence

The diffusion and coalescence of Au–Cu alloy nanoparticles was studied at high magnification using in situ transmission electron microscopy. The particles prepared by physical vapor deposition onto amorphous-C support films had an average composition of Cu–43 at% Au and diameters of 15–50 nm. In the case analyzed, the larger of two nanoparticles remained stationary throughout the coalescence process while a smaller nanoparticle moved toward the larger particle at a temperature of ~573 K. The surface of the small nanoparticle was observed to fluctuate while approaching the larger particle, demonstrating that collective atom process occurs along the particle periphery. The particle also decreased in size during the process, indicating that it was losing mass as well as migrating. Direct evidence of a diffusional flux between particles was observed before the coalescence process. The small nanoparticle coalesced into the large one at a highly accelerated rate compared to its prior migration.     

Incorporation of non-conjugated polymer chain in conjugated polymer matrix: A new single step strategy for free standing non-volatile polymer memory

A new single step strategy for polymer memory materials has been explored using free-standing polypyrrole (PPy) film in which non-conjugated polymer chains are incorporated as trap states during synthesis. The PPy film was synthesized by the acidic oxidation of 2,2′:5′,2′′-terpyrrole at the air/water interface. The free-standing PPy films show large hysteresis along with current peaks in opposite directions during current voltage (I–V) characteristics. Hysteric behavior has been utilized to show rewritable memory effect. Furthermore, once electrical state (high or low conduction state) is set, the state is stable for months in ambient condition unless the state is reset by applying a voltage of opposite polarity. Thus the PPy film can be used as read once memory. The memory effect of the film is due to the conformational changes of non-conjugated polymer chains in the PPy matrix. The changes in conformation were confirmed from UV–Vis and FTIR spectra. This new strategy leads free-standing film based all organic polymer memory devices at ultra low cost.