Building accurate radio environment maps from multi-fidelity spectrum sensing data

In cognitive wireless networks, active monitoring of the wireless environment is often performed through advanced spectrum sensing and network sniffing. This leads to a set of spatially distributed measurements which are collected from different sensing devices. Nowadays, several interpolation methods (e.g., Kriging) are available and can be used to combine these measurements into a single globally accurate radio environment map that covers a certain geographical area. However, the calibration of multi-fidelity measurements from heterogeneous sensing devices, and the integration into a map is a challenging problem. In this paper, the auto-regressive co-Kriging model is proposed as a novel solution. The algorithm is applied to model measurements which are collected in a heterogeneous wireless testbed environment, and the effectiveness of the new methodology is validated.     

Development of colorimetric cholesterol detection kit using TPU nanofibre/cellulose acetate membrane

In this study, the authors report a simple fabrication of thermoplastic polyurethane (TPU) nanofibres‐based kit for cholesterol detection. TPU is a polymer that is highly elastic, resistant to microorganisms, abrasion and compatible with blood; thus, making it a natural selection as an immobilisation matrix for cholesterol oxidase (ChOx) enzyme. The nanofibre was fabricated by electrospinning process and was characterised using scanning electron microscopy and Fourier transform‐infrared spectroscopy. ChOx was covalently immobilised on TPU nanofibre and cholesterol level/concentration was visually found using 4‐aminoantipyrine, a dye that reacts with H₂ O₂ produced from the oxidation of cholesterol by ChOx and changes colour from yellow to red. The efficacy of the nanofibre to act as a detecting substrate was compared with cellulose acetate (CA) membrane, a well‐documented enzyme immobilisation matrix. The optimisation of enzyme concentration and dye quantity were performed using standard ChOx spectrophotometric assay and the same was used in CA membrane and TPU nanofibre. The ChOx immobilised nanofibre showed good linear range from 2 to 10 mM with a lower detection limit of 2 mM and was highly stable compared to that of CA membrane. The enzyme immobilised nanofibre was further validated in serum samples.Inspec keywords: colorimetry, nanofibres, biomembranes, biosensors, nanosensors, nanofabrication, polymer fibres, elasticity, nanomechanics, biomechanics, blood, nanomedicine, biomedical equipment, enzymes, molecular biophysics, molecular configurations, biochemistry, abrasion, biomedical materials, electrospinning, scanning electron microscopy, Fourier transform infrared spectra, dyes, oxidation, spectrophotometryOther keywords: colorimetric cholesterol detection kit, TPU nanofibre‐cellulose acetate membrane, thermoplastic polyurethane nanofibres‐based kit, highly elastic polymer, microorganisms, abrasion, blood compatibility, natural selection, immobilisation matrix, cholesterol oxidase ChOx enzyme, electrospinning, scanning electron microscopy, Fourier transform‐infrared spectroscopy, TPU nanofibre, cholesterol level‐concentration, 4‐aminoantipyrine, H₂ O₂ production, oxidation, cellulose acetate membrane, enzyme immobilisation matrix, enzyme concentration, optimisation, dye quantity, standard ChOx spectrophotometric assay, enzyme immobilised nanofibre, serum samples     

A high-sensitivity z-axis capacitive silicon microaccelerometerwith a torsional suspension

This paper presents a new z-axis high-sensitivity silicon-micromachined capacitive accelerometer fabricated using a three-mask dissolved-wafer process (DWP). It employs capacitive sensing using overlap-area variations between comb electrodes and a torsional suspension system to provide high sensitivity without compromising bandwidth, full-scale range, or the pull-in voltage ceiling. Excellent electrical sensitivity is obtained by using high-aspect-ratio comb fingers with narrow air gaps of 2 μm and a large overlap area of 12 μm ×300 μm. Torsional suspension beams 150 μm long with a cross-sectional area of 12 μm ×3 μm are used to improve the mechanical gain. Simulations of the capacitance between sense fingers show a highly linear region over a wide 14-μm tip deflection range. Accelerometers were fabricated and yielded sensitivities of 263-300 mV/g, a nonlinearity less than 0.2% over a range of -4 to +3 g, a full-scale range of -4 to +6 g, and pull-in voltages greater than 8 V. A 3 dB cutoff frequency of 35 Hz was measured in air. The calculated thermomechanical noise in the sensor is 0.28 mg over this bandwidth     

Secure dynamic anycasting for ‘best’ server selection using active networks

The networking community has tackled the resource-finding problem using several methods. The knowledge of the name or property of the resource enables one to find it over the network. Many techniques were proposed and investigated for a single instance of the resource. The Internet has experienced dramatic growth in the use and provision of services such as ftp, gopher, archie and World-Wide-Web. The heavy demands being placed on servers inspire replication (mirroring) of servers. This replication results in client intending to contact the ‘best’ server among many content-equivalent servers.

The solutions that were used for the ‘best’ server selection include multicast and broadcast communication to send request to all servers and choose the best one from all the replies. These solutions require the client to be powerful enough to handle all the replies, which may be overwhelming leading to client's machine getting hung. The other solution uses the name servers to provide a different unicast address for one member of a group of servers at different locations. The inherent disadvantage in this method is that the user is unable to choose the best server. The idea of application layer anycasting allows the user to select the best server according to the user's selection criteria. The main disadvantage of this scheme is that the client that does the selection may not be powerful to handle responses from all the content-equivalent servers. In this paper the idea of application layer anycasting has been extended by allowing the active routers to locate the best server. Active networks, unlike the traditional networks are not just passive carrier of bits but instead provides the capability for the user to inject customized programs into the networks that may modify, store or redirect the user data flowing through the network. Anycasting is done in the application level as it provides better end-to-end control, and there is no support in the network level. The choice of ‘best’ server is done based on the first response from the servers. The active routers do the filtering of responses from laggards and the client gets the response only from the best server, thus the client machine is not overwhelmed by responses. The client deals with the vital issue of security with respect to Active networks by the use of various encryption schemes. Since the ‘best’ server chosen is not always the best forever, a TTL value is associated with each of the best server found, and the best one is reselected after its expiry.

The performance of the proposed scheme is compared with the networks without active networks and is found to provide better response time for requests. Further, the proposed scheme avoids the overloading of a server, jockeying, and reduces the overhead of the client in selecting the best server. The overhead on the routers in active networks is insignificant compared to the advantages accrued due to it.     

Detection of collision using optimized deep model and mitigation of collision using dolphin ant lion optimizer in wireless sensor network

Wireless sensor network (WSN) comprises automatic sensors that are dispersed into a huge region. WSN is constructed from huge sensors, which is allocated to a particular task and the majority of task involves reporting and monitoring. However, as the network can be extended to several sensor nodes, there is a high chance of collision. Thus, this paper devises a novel technique for performing both collision detection and mitigation in WSN. Initially, the simulation of WSN is performed, and then the selection of cluster head is done using fractional artificial bee colony (FABC). Here, the network-based parameter is extracted that involves received signal strength index (RSSI), priority level, delivery rate, and energy consumed. The deep recurrent neural network (DRNN) is adapted for collision detection. Here, the training of DRNN is done using lion crow search optimizer (LCSO). After collision detection, the collision mitigation is performed with a pre-scheduling algorithm, namely dolphin ant lion optimizer (Dolphin ALO). Here, fitness is considered for collision mitigation that includes energy, sleep index (SI), delivery rate, priority level, E-waste, and E-save. The proposed method outperformed with the smallest energy consumption of 0.185, highest throughput of 0.815, highest packet delivery ratio (PDR) of 0.815, and highest collision detection rate of 0.930.     

3,5‐Bis(benzylidene)‐4‐oxo‐1‐phosphonopiperidines and Related Diethyl Esters: Potent Cytotoxins with Multi‐Drug‐Resistance Reverting Properties

A series of 3,5‐bis(benzylidene)‐4‐piperidones 3 were converted into the corresponding 3,5‐bis(benzylidene)‐1‐phosphono‐4‐piperidones 5 via diethyl esters 4 . The analogues in series 4 and 5 displayed marked growth inhibitory properties toward human Molt 4/C8 and CEM T‐lymphocytes as well as murine leukemia L1210 cells. In general, the N‐phosphono compounds 5 , which are more hydrophilic than the analogues in series 3 and 4 , were the most potent cluster of cytotoxins, and, in particular, 3,5‐bis‐(2‐nitrobenzylidene)‐1‐phosphono‐4‐piperidone 5 g had an average IC₅₀ value of 34 nM toward the two T‐lymphocyte cell lines. Four of the compounds displayed potent cytotoxicity toward a panel of nearly 60 human tumor cell lines, and nanomolar IC₅₀ values were observed in a number of cases. The mode of action of 5 g includes the induction of apoptosis and inhibition of cellular respiration. Most of the members of series 4 as well as several analogues in series 5 are potent multi‐drug resistance (MDR) reverting compounds. Various correlations were noted between certain molecular features of series 4 and 5 and cytotoxic properties, affording some guidelines in expanding this study.     

Novel Proton-Conducting Polymer Electrolytes Based on Poly(Vinylidene fluoride-co-hexafluoropropylene)–Ammonium Thiocyanate

The polymer electrolytes composed of poly(vinylidene fluoride-co-hexafluoropropylene) with various concentration of ammonium thiocyanate salt have been prepared by solution casting technique. The complex formation between polymer and dissociated salt has been confirmed by X-ray diffraction analysis and Fourier transform infrared spectroscopy. The highest conductivity has been found to be 6.5?×?10^?3?S?cm^?1 at 343?K for 25?wt% ammonium thiocyanate. The temperature-dependent conductivity of polymer electrolyte follows Arrhenius hopping relation. Thermogravimetric analysis has been used to ascertain the thermal stability of the polymer electrolytes. Atomic force microscopy analysis predicts the roughness parameter of the sample with higher conductivity.     

A study on the effect of bulk water content and drying temperature on the colour of dyed cotton fabrics

In the present study, the effect of various levels of bulk and free water content and its distribution on the colour of cotton fabrics dyed with direct dyes and their combinations were analysed. Twill and plain structures with two different parameters of fabric construction were chosen. The dyed samples were adjusted to different levels of wet pick‐up, with water ranging from 50% to 125% on the bone dry weight of the fabric (odwf) to achieve various levels of bulk water content. Further, the residual moisture content of the samples was adjusted to 40–10% odwf by means of hot air drying at different temperatures to obtain different levels of free water content and its distribution. For the assessment of colour and its comparison, the parameters ΣK/S and values were used. In order to bring out the true effect of moisture distribution and fabric structure, normalisation of dye uptake in the fabric based on weight and area were considered, respectively. The plain structures show a higher increase in colour than the twill structures when the bulk water content increases. At the same time, the fabric structures do not play a significant role, with increase in colour attributable to change in drying temperature. The findings reveal that the bulk water content, drying temperature and fabric geometry affects the colour of the fabric significantly.