ORuML: Optimized Routing in wireless networks using Machine Learning

Routing is a process of selecting a path in a network for delivering a packet from source node to destination node. Successful delivery of a message is a challenge, and therefore, this paper proposes an algorithm for a wireless network called Optimized Routing in wireless networks using Machine Learning (ORuML), which uses machine learning algorithm namely, K‐nearest neighbor (KNN), Support Vector Machine (SVM), and Multinomial Logistic Regression (MLR), to predict the network type of the source and destination nodes. The ML model is trained by using characteristic features of a node collected in real time such as battery power utilization, available internal storage, IP address, and range of a node. Intuitively, the MLR should outperform KNN and SVM in terms of accuracy and Area under ROC Curve (AUC). The proposed algorithm determines whether the source and destination nodes are co‐located and also, determines the best neighboring hop for efficient routing.     

A new dual C‐shaped rectangular dielectric resonator based antenna for wideband circularly polarized radiation

This article presents a new dual C‐shaped rectangular dielectric resonator (DR) based antenna for generation of wideband circularly polarized (CP) radiation. The proposed antenna comprises of a pair of C‐shaped rectangular dielectric DR and a metal strip with a coaxial probe. By utilization of a metal strip at the side surface of C‐shaped rectangular DR, the wideband CP radiation is achieved from the proposed dielectric resonator antenna (DRA). Fundamental orthogonal modes (TE^x_δ11 and TE^y_1δ1) are excited using the rectangular DRA with a metal strip for the generation of CP fields. The proposed antenna with dual C‐shaped rectangular CP DRA provides the measured ?10 dB reflection coefficient bandwidth of 30.07% (3.22 GHz‐4.36 GHz) with measured 3‐dB axial ratio bandwidth of 14.81% (3.25 GHz‐3.77 GHz) at the boresight. The proposed antenna covers the useful Wi‐MAX band.     

A coaxial probe fed wideband circularly polarized antenna using unequal and adjacent‐slided rectangular dielectric resonators for WLAN applications

In this article, a coaxial probe fed wideband circularly polarized antenna has been designed and investigated using unequal and adjacent‐slided rectangular dielectric resonators radiating in broadside direction (Φ = 0°, θ = 0°). Wi‐Fi wireless network use radio signal either in 2.4 or 5 GHz band. Owing to high rush in 2.4 GHz band, the proposed antenna is designed for 5 GHz (5.15‐5.825 GHz) WLAN band. The proposed design uses fundamental orthogonal modes and excited in two individual rectangular dielectric resonators to achieve wide axial‐ratio bandwidth (below 3 dB). Measured input reflection coefficient (below ?10 dB) and axial ratio bandwidth (below 3 dB) of 26.07% (5.27‐6.85 GHz) and 26.85% (5.32‐6.97 GHz) has been attained, respectively, in this proposed antenna. The measured far‐field patterns such as gain and radiation patterns are showing consistent performance throughout the working band.     

Circularly polarized rectangular DRA coupled through orthogonal slot excited with microstrip circular ring feeding structure for Wi‐MAX applications

In this article, a wideband circularly polarized rectangular dielectric resonator antenna (RDRA) coupled through orthogonal slots and excited with a new microstrip circular ring has been investigated. Circular polarization has been achieved by using plus shaped (+) slot on the ground plane and excited through a new microstrip circular ring feed. TE_11δ mode has been excited in the RDRA which has been confirmed through the distribution of E ‐field and dielectric waveguide model (DWM) method of RDRA. Circularly polarized (CP) RDRA offering measured ?10 dB input impedance bandwidth of 20.79% (centered at 3.27 GHz) and 3 dB axial ratio bandwidth in broadside direction of 12.09% (centered at 3.39 GHz), respectively. From the CP radiation pattern, proposed design confirms that right ‐ handed CP (RHCP) in broadside direction. The difference between RHCP field and left ‐ handed CP (LHCP) field are above ?26 dB in operational band. In addition, the proposed CP antenna offers stable gain and radiation efficiency in working bands and it is suitable for IEEE 802.16e/d Wi‐MAX (3.3‐3.7 GHz) band.     

Investigation of higher order modes excitation through F‐shaped slot in rectangular dielectric resonator antenna for wideband circular polarization with broadside radiation characteristics

In this article, a wideband circularly polarized rectangular dielectric resonator antenna (RDRA) with broadside radiation characteristics has been proposed. By using modified ground plane having an F‐shaped slot, the proposed structure able to generates three sets of modes i.e., fundamental as well as higher order modes. To obtained circular polarization, an orthogonal mode (TE₁₁₃) in the RDRA has been generated by using the F‐shaped slot on the modified ground plane. The resonance frequency of fundamental mode (TE₁₁₁) in the rectangular dielectric resonator (DR) has been calculated by using dielectric waveguide model method. The same has been confirmed through E‐field distribution in RDRA. Here, wide axial ratio (AR) bandwidth of the proposed antenna is due to the generation of and modes. It is observed that input impedance bandwidth has been broadening with a pair of excited modes ( and modes) in the proposed antenna structure. All these modes have been excited and merged to form a wide input impedance bandwidth and wide AR bandwidth of the designed antenna. The proposed antenna shows measured input reflection coefficient (S₁₁ < ?10 dB) of 50.55% and measured AR bandwidth (AR < 3 dB) of 14.28%. The designed antenna shows left‐handed circular polarization in broadside direction and offering an average gain and radiation efficiency of 4.29 dBic and 92.22% respectively.     

Radio-over-free space optical space division multiplexing system using 3-core photonic crystal fiber mode group multiplexers

Wireless Networks - Radio over free space optics&nbsp;(Ro-FSO) systems have previously relied on the&nbsp;signal intensity, wavelength and polarization for multiplexing data streams in...     

Excellent Intrinsic Long-Term Thermal Stability of Co-Evaporated MAPbI3 Solar Cells at 85 °C

Thermal stability is a critical criterion for assessing the long-term stability of perovskite solar cells (PSCs). Here, it is shown that un-encapsulated co-evaporated MAPbI₃ (TE_MAPbI₃) PSCs demonstrate remarkable thermal stability even in an n-i-p structure that employs Spiro-OMeTAD as hole transport material (HTM). TE_MAPbI₃ PSCs maintain over ≈95% and ≈80% of their initial power conversion efficiency (PCE) after 1000 and 3600 h respectively under continuous thermal aging at 85 °C. TE_MAPbI₃ PSCs demonstrate remarkable structural robustness, absence of pinholes, or significant variation in grain sizes, and intact interfaces with the HTM, upon prolonged thermal aging. Here, the main factors driving TE_MAPbI₃ stability are assessed. It is demonstrated that the excellent TE_MAPbI₃ thermal stability is related to the perovskite growth process leading to a compact and almost strain-stress-free film. On the other hand, un-encapsulated PSCs with the same architecture, but incorporating solution-processed MAPbI₃ or Cs_0.05(MA_0.17FA_0.83)_0.95Pb(I_0.83Br_0.17)₃ as active layers, show a complete PCE degradation after 500 h under the same thermal aging condition. These results highlight that the control of the perovskite growth process can substantially enhance the PSCs thermal stability, besides the chemical composition. The TE_MAPbI₃ impressive long-term thermal stability features the potential for field-operating conditions.     

Studies of the curing kinetics and thermal stability of epoxy resins using a mixture of amines and anhydrides

This article describes the curing and thermal behavior of diglycidyl ether of bisphenol A with phthalic anhydride (PA)/pyromellitic anhydride/diaminodiphenyl sulfone (DDS) or a mixture of anhydrides and amines in varying ratios as curing agents. The kinetics of the curing behavior was investigated with a multiple‐rate method. The activation energy of the curing reaction as determined in accordance with Ozawa's method was found dependent on the structure of the anhydride and on the ratio of amines to anhydrides. The activation energy was highest with sample DP3 (0.25 : 0.75) and DM3 (0.25 : 0.75). We evaluated the thermal stability of epoxy resin, cured isothermally, by recording thermogravimetric traces in a nitrogen atmosphere. The char yield was highest for resins cured with a mixture of DDS and PA (0.5 : 0.5) and a mixture of DDS and pyromellitic dianhydride (0.25 : 0.75). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3919–3925, 2006     

The use of chromium waste sludge for the adsorption of colour from dye effluent streams

Adsorption studies show that chromium hydroxide precipitates can be used for the removal of methylene blue, reactive blue, congo red and disperse orange dyes from aqueous media. Three different mechanisms are involved: attraction of positive surface charges on the precipitate at low pH for dye anions (reactive blue and congo red); attraction of negative surface charges on hydroxide at high pH for dye cations (methylene blue), and dye particle entrapment for the neutral disperse orange. The point of zero charge of the chromium hydroxide precipitate based on the dye adsorption studies is pH 10.5. The changes in the surface charge of such precipitates with pH can be used to achieve the removal of any charged dye species. © 2002 Society of Chemical Industry     

Discovery of Aporphine Analogues as Potential Antiplatelet and Antioxidant Agents: Design,Synthesis, Structure–Activity Relationships,Biological Evaluations,and in silico Molecular Docking Studies

To explore the potential of aporphine alkaloids, a novel series of functionalized aporphine analogues with alkoxy (OCH₃, OC₂H₅, OC₃H₇) functional groups at C1/C2 of ring A and an acyl (COCH₃ and COPh) or phenylsulfonyl (SO₂Ph and SO₂C₆H₄‐3‐CH₃) functionality at the N6 position of ring B of the aporphine scaffold were synthesized and evaluated for their arachidonic acid (AA)‐induced antiplatelet aggregation inhibitory activity and 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) free‐radical‐scavenging antioxidant activity, with acetylsalicylic acid and ascorbic acid as standard references, respectively. The preliminary structure–activity relationship related to AA‐induced platelet aggregation inhibitory activity results showed that the aporphine analogues 1‐[1,2,9,10‐tetramethoxy‐6a,7‐dihydro‐4H‐dibenzo[de,g]quinolin‐6(5H)‐yl]ethanone and 1‐[2‐(benzyloxy)‐1,9,10‐trimethoxy‐6a,7‐dihydro‐4H‐dibenzo[de,g]quinolin‐6(5H)‐yl]ethanone to be the best compounds of the series. Moreover, the DPPH free‐radical‐scavenging antioxidant activity results demonstrated that the aporphine analogues 1,2,9,10‐tetramethoxy‐6‐(methylsulfonyl)‐5,6,6a,7‐tetrahydro‐4H‐dibenzo[de,g]quinoline, 2‐ethoxy‐1,9,10‐trimethoxy‐6‐(methylsulfonyl)‐5,6,6a,7‐tetrahydro‐4H‐dibenzo[de,g]quinoline, 1‐ethoxy‐2,9,10‐trimethoxy‐6‐(methylsulfonyl)‐5,6,6a,7‐tetrahydro‐4H‐dibenzo[de,g]quinoline, 2,9,10‐trimethoxy‐6‐(methylsulfonyl)‐1‐propoxy‐5,6,6a,7‐tetrahydro‐4H‐dibenzo[de,g]quinoline, and 1‐(benzyloxy)‐2,9,10‐trimethoxy‐6‐(methylsulfonyl)‐5,6,6a,7‐tetrahydro‐4H‐dibenzo[de,g]quinoline were the best compounds of the series. Moreover, in silico molecular docking simulation studies of the active analogues were also performed.