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In the present work, structural and dielectric properties of 0.7 P b Z r 0.52 T i 0.48 O 3 − 0.3 C o F e 2 O 4 composite prepared by a mixed oxides route were explored. X-ray diffraction analyses confirmed the formation of distinct C o F e 2 O 4 and P b Z r 0.52 T i 0.48 O 3 phases in the prepared composite. Temperature dependent dielectric permittivity behavior displayed three distinct peaks: a frequency independent peak at high temperature (T = 663K) is identified as structural phase transition of P b Z r 0.52 T i 0.48 O 3 and two thermally activated frequency dependent peaks which showed a Debye- and relaxor-like behaviors at low and intermediate temperatures, respectively. The mechanism for these relaxations is elucidated on the basis of conduction associated with the single- and doubly-ionized oxygen vacancies. Impedance spectroscopy analysis was used to estimate the activation energy ( E a ) of constituent phases and we found that P b ( Z r 0.52 T i 0.48 ) O 3 phase has a dominant role (i.e., E P Z T > E C F O ) in describing the relaxation/conduction mechanism of prepared composite. Moreover, the values of E a calculated from the dielectric, impedance and conductivity data were found to be comparable which clearly indicate that the relaxation and conduction processes in the prepared composite are related to same origin.

In the current era of IoT, home appliances like dishwashers, washing machines, and coffee makers, etc. are being equipped with internet access and sensing resources to provide autonomous or semi-autonomous functionality to its users. It is foreseeable that these appliances will soon be capable to collaborate by sharing their capabilities enabling dynamic operations as per the context and user preferences. This scenario, however, will also add to the complexity of programming/customizing the operational behavior of the appliances. Hence, traditional control interfaces will not suffice. This paper presents a generic architecture through which such collaborative operations of home appliances can be achieved. To minimize complexity for end-users, a centralized drag-n-drop visual interface for operational customization of the home appliances has been presented. In this proof-of-concept implementation, Intel Edison Platforms with associated sensing and actuating components have been utilized to mimic the sensing, actuation and computational resources of future home appliances by utilizing local WIFI network for communication purposes. Simple collaboration scenarios have been executed to find the execution delay of the customized collaborative operations. Based on the same scenarios, a preliminary usability study, based on system usability scale (SUS), has been conducted for the centralized visual interface via two different groups of end-users (programming skills-based). The average SUS score of 79.2 by both groups backs the claim of reduced complexity and ease of use for the end-users.

The performance of conventional repetitive controller (RC) deteriorates under frequency variations and system uncertainties. Due to limited bandwidth, it is also a trivial task to stabilize the conventional RC. This paper proposes a higher-order repetitive controller (HORC) with linear phase lead as a stabilizing compensator and zero-phase tracking error (ZPTE) compensator. The periodic signal generator, used by the HORC, offers relatively high gains in the neighborhood of tuned frequency and its harmonics. Stability conditions for higher-order repetitive (HOR) control system, including the phase lead compensator, are presented. The proposed solution is applied to repetitive current control of a two-level grid-connected inverter. Simulation and experimental results show that the HORC designed using the phase lead compensation is robust to frequency variation in reference/disturbance and system uncertainties.

Organic-inorganic hybrid perovskites have recently attracted substantial attention as a top candidate for use as light-absorbing materials in high-efficiency, low-cost and solution-processable photovoltaic devices owing to their excellent optoelectronic properties. Here, we fabricated inverted planar perovskite solar cells by incorporating small amounts of ammonium halide NH4X (X = F, Cl, Br, I) additives into a CH3NH3PbI3 (MAPbI3) perovskite solution. A compact and uniform perovskite absorber layer with large perovskite crystalline grains is realized by simply incorporating small amounts of additives and by using an anti-solvent engineering technique to control the nucleation and crystal growth of perovskite. The enlarged perovskite grain size with a reduced density of the grain boundaries and improved crystallinity results in fewer charge carrier recombinations and a reduced defect density, leading to enhanced device efficiency (NH4F: 14.88 ± 0.33%, NH4Cl: 16.63 ± 0.21%, NH4Br: 16.64 ± 0.35%, and NH4I: 17.28 ± 0.15%) compared to that of a reference MAPbI3 device (Ref.: 12.95 ± 0.48%) and greater device stability. This simple technique involving the introduction of small amounts of ammonium halide additives to regulate the nucleation and crystal growth of perovskite films translates into highly reproducible enhanced device performance.

Since aggregation of protein result into number of human diseases including diabetes mellitus, Huntington's and Alzheimer's disease, etc. Hence prevention of aggregation of a polypeptide is of great clinical importance. Human serum albumin (HSA) being major transporter serum protein was studied here in order to prevent its aggregation under extreme conditions. Sulfamethoxazole (SMZ) which is an antibiotic, caused significant inhibition of aggregation which was evident by number of biophysical techniques. Molecular docking was performed to elucidate the protein ligand binding site. In the presence of SMZ decrease in ThT, ANS and RLS fluorescence intensity suggested the inhibitory potency of this antibiotic. Further resistance to increment in the absorbance of Congo red and turbidity was observed even at elevated temperature. Circular dichroism also corroborated these results in retaining its secondary structure in the presence of SMZ. Finally the formation of aggregates, visualized under transmission electron microscopy (TEM) validated the inhibitory tendency of SMZ. Also in the parallel sets we have monitored aggregation kinetics using ThT and turbidity assay and it is noteworthy that SMZ caused maximum inhibition at protein SMZ concentration ratio of 1:30 and 1:40. Our findings would set a hallmark for designing new therapeutics for untreatable protein conformational disorders.

Protein and peptides are converted from their soluble forms into highly ordered fibrillar aggregates under various conditions inside the cell. Such transitions confer diverse neurodegenerative diseases including Alzheimer's disease, Huntington's disease Prion's disease, Parkinson's disease, polyQ and share abnormal folding of potentially cytotoxic protein species linked with degeneration and death of precise neuronal populations. Presently, major advances are made to understand and get detailed insight into the structural basis and mechanism of amyloid formation, cytotoxicity and therapeutic approaches to combat them. Here we highlight classifies and summarizes the detailed overview of protein misfolding and aggregation at their molecular level including the factors that promote protein aggregation under in vivo and in vitro conditions. In addition, we describe the recent technologies that aid the characterization of amyloid aggregates along with several models that might be responsible for amyloid induced cytotoxicity to cells. Overview on the inhibition of amyloidosis by targeting different small molecules (both natural and synthetic origin) have been also discussed, that provides important approaches to identify novel targets and develop specific therapeutic strategies to combat protein aggregation related neurodegenerative diseases.

Metal ions play a vital role in the aggregation of proteins by interfering with their correct folding, thereby affecting protein homeostasis and cell viability, leading to neurodegenerative diseases like Alzheimer's and Parkinson's. Development of therapeutics against protein misfolding diseases has become one of the widely studied areas of research. Till date, all advances in neurodegenerative diseases' therapeutics help symptomatically but do not prevent the root cause of the disease, i.e., the aggregation of protein involved in the diseases. Recent studies show a promising potential for metal based therapy utilising metal chelators. In this regard, we aimed to study the behaviour of gallic acid, a well characterised anti-aggregation compound, towards inhibition of metal-induced aggregation of a model enzyme, the human lysozyme. Using various spectroscopic and microscopic techniques we show that gallic acid inhibits metal induced aggregation. We delineate that gallic acid inhibits metal-induced aggregation by chelating the metal ions in the solvent, thereby inhibiting the aggregation of human lysozyme as demonstrated by our spectroscopic results which showed the formation of a complex between Mg2+ and gallic acid. Our studies showed retention of lysozymal activity upto 63.2% in presence of gallic acid. Our study therefore shows that gallic acid exhibits bifunctional inhibitory roles i.e., as an anti amyloidogenic and metal induced aggregation inhibitor. Due to its metal chelating activity, gallic acid can be further developed in metal based therapy against neurodegenerative diseases.

Naphthalene diimide (NDI)-based copolymers are promising polymer acceptors in all-polymer solar cells (all-PSCs), but their large crystal domains cause large-scale phase separation in all-polymer blend films. This limits the photovoltaic performance and mechanical stability of all-PSCs. Herein, we control all-polymer blend films by introducing a fluorinated copolymer of NDI and (E)-1,2-bis(3-fluorothiophen-2-yl)ethene (FTVT) (PNDI–FTVT) as a polymer acceptor for flexible all-PSCs. The copolymer PNDI–FTVT has a less crystalline structure and higher electron mobility than its nonfluorinated copolymer counterpart (PNDI–TVT). A blended film incorporating PNDI–FTVT exhibits a well-mixed morphology and improves the chain interconnectivity with a polymer donor, providing better charge transport pathways and enhanced mechanical resilience. The PNDI–FTVT-based flexible all-PSC exhibits enhanced photovoltaic performance in comparison with a PNDI–TVT-based flexible all-PSC (5.11–7.14%) as well as excellent mechanica...

The (CuTl)0.5Ba2Ca2Cu3O10−δ {CuTl-1223} superconducting phase was synthesized by a well-established solid-state reaction route and the semiconducting antiferromagnetic cobalt oxide (Co3O4) nanoparticles were prepared by a chemical sol–gel method. The final (Co3O4)x/(CuTl)-1223; (x = 0–2.0 wt.%) nanoparticles–superconductor composites were obtained by adding Co3O4 nanoparticles in CuTl-1223 phase of the CuTl-based superconducting family. A temperature range of 77–298 K was chosen for frequency-dependent electric modulus spectroscopy measurements of (Co3O4)x/(CuTl)-1223 composites to interpret the dynamical aspects of electrical transport phenomena, such as ac-conductivity, carrier hopping rate, etc. The influence of grains as well as the grain boundaries on the ac-conduction properties was witnessed from the complex electric modulus spectra of these composite samples. The grain boundaries showed higher capacitance compared with the grains. This behavior of capacitance was decreased for grain boundaries and increased for grains with higher values of operating temperature in all the superconducting composite samples. The shifting of peaks towards a lower frequency regime in imaginary parts of the electric modulus spectra with increasing Co3O4 nanoparticle contents showed the presence of non-Debye-type relaxation within the material. The effects of these semiconducting antiferromagnetic Co3O4 nanoparticles on the ac-conduction mechanism of the host CuTl-1223 phase were studied, particularly in the perspective of the capacitive resistance contribution via electric modulus spectroscopy measurements.

The structural and magnetic properties of Ni50Mn33In17 were investigated by means of synchrotron X-ray diffraction and magnetization measurements. In contrast to well established critical concentration of x ≤ 16.0 for Ni50Mn50−xInx alloys to undergo structural transformation, we have found Ni50Mn33In17 to undergo austenite to martensite structural transition around 170 K. At room temperature, the Rietveld refinement of X-ray diffraction measurements revealed a L21 Heusler cubic structure belonging to Fm 3 m space group while the low temperature martensite structure belongs to a monoclinic space group P 2 / m . Temperature dependent magnetization measurements confirmed a near room temperature paramagnetic to ferromagnetic magnetic transition as well as a magnetostructural transition at ∼170 K while magnetic field induced reverse martensite transformation was also confirmed. An inverse magnetocaloric effected associated with the magnetostructural transition is also observed with magnetic entropy change Δ S M reaching ∼13.0 J/kg-K around 175 K under field change of 0–6 T. The inverse magnetocaloric effect occurs in a wide temperature range of 125–200 K with a relatively high refrigerant capacity of about 200 J/kg. This makes Ni50Mn33In17 a promising magnetic refrigerant in the mentioned range of temperature as well as for further studies of effect of excess Mn on magnetic and structural properties of Ni50Mn50−xInx alloys.

Spontaneous capillary imbibition plays a significant role in oil displacement mechanism during water flooding operation in extra-low permeability sandstone reservoirs. However, after long-term of waterflooding, most of the oil blobs still remain within the pore space. In this context, quantitative assessment of the micro-occurrence of remaining oil in pore space is indispensable to conduct for an efficient waterflooding operation. In this work, the core sample with 3 mm × 10 mm dimensions was prepared from the southeast area of Ordos Basin Chang6 extra-low permeability formation. Subsequently, high-resolution X-rays CT scanning technology was employed to visualize the changes in fluid distribution during spontaneous imbibition process. By means of image segmentation and three-dimensional (3-D) image reconstruction technique, the images of the remaining oil in the 3-D pore space were obtained. After that, the shape factor and relative volume factor were used to quantify the micro-occurrence of remaining oil in the 3-D pore space. The experimental results show that the total volume of oil was declined to 2.27 × 107 μm3 from 4.25 × 107 μm3 after spontaneous imbibition in the core sample. Consequently, the continuous oil phase was disrupted by the water in pore space and segmented oil blocks were appeared. Meanwhile, the number of oil blocks was increased to 6027 from 958 that led to severe Jamin’s effect and spontaneous imbibition was resultantly came to an end. While in 3-D pore space, three different kinds of micro-occurrences of remaining oil were spotted, such as network (54.31%), cluster (35.28%), and isolated (10.51%). The network and cluster type of remaining oil micro-occurrences are considered as dominant types owing to the large volume and better communication. Because of abrupt capillary force reduction in suddenly enlarge channel and multiple Jamin’s effects, the network and cluster remaining oil would mainly be confined in large channels (over than peak pore radius). Therefore, our work provides some beneficial understanding of the remaining oil micro-occurrence in pore space after imbibition.

Breast cancer is the second most common cause of cancer-related deaths among women. Early detection leads to better prognosis and saves lives. The 5-year survival rate of breast cancer is 99% if it is located only in breast. Conventional computer-aided diagnosis (CADx) systems for breast cancer use the single view information of mammograms to assist the radiologists. More recent work has focused on more than one views. Existing multi-view based CADx systems normally employ only two views namely Cranio-Caudal (CC) and Medio-Lateral-Oblique (MLO). The information fusion of the two views proved the effectiveness of the system for mammogram classification which cannot be achieved by single view information. However, combining the information of four views of mammograms increases the performance of classification. In this study, we propose Multi-View Feature Fusion (MVFF) based CADx system using feature fusion technique of four views for classification of mammogram. The complete CADx tool contains three stages, the first stage have the ability to classify mammogram into abnormal or normal, second stage is about classification of mass or calcification and in the final stage classification of malignant or benign classification is performed. Convolutional Neural Network (CNN) based feature extraction models operate on each view separately. These extracted features were fused into one final layer for ultimate prediction. Our proposed system is trained on four views of mammograms, after data augmentation. We performed our experiments on publicly available datasets such as CBIS-DDSM (Curated Breast Imaging Subset of DDSM) and mini-MIAS database of mammograms. In comparison with literature the MVFF based system is performed better than a single view-based system for mammogram classification. We have achieved area under ROC curve (AUC) of 0.932 for mass and calcification and 0.84 for malignant and benign, which is higher than all single-view based systems. The value of AUC for normal and abnormal classification is 0.93.

Address resolution protocol (ARP) cache poisoning is mostly used to perform man‐in‐the‐middle (MITM) and denial of service (DoS) attacks for sniffing and network services disruption, respectively, in switch LAN networks. The former attack affects the privacy of a network user, whereas the latter attack causes huge damage to networks in terms of unavailability of services. There are many security solutions that provide protection against such type of attacks at firewall level with the assumption that an insider attack does not exist. However, the most damaging and severe attacks on universities database servers to well‐known banking system have been caused by insider malicious users. In this study, the authors propose an agent‐based ARP cache poisoning detection (AACPD) scheme that detects the MITM and DoS attacks in a switch LAN environment. The objective of this scheme is to provide protection from insider malicious users. The proposed AACPD is compared with similar existing schemes in a real‐time environment. The experimental results show that AACPD efficiently and accurately detects attackers with minimum effect on network performance as compared to similar existing schemes.

The degradation of organic contaminants under high salinity condition is still a challenge for environmental remediation due to the inhibiting effect resulted from the side reactions between radicals and anions. Here, we demonstrate the non-radical oxidation process via peroxymonosulfate (PMS) activation by metal-free carbon catalyst for efficiently decomposing bisphenol A (BPA) in saline water. The nitrogen-doped graphitic carbon (NGC700) exhibits excellent catalytic activity for depredating BPA at acid and neutral pH. Based on the scavenger experiments and electron paramagnetic resonance (EPR) analyses, the mechanism of catalytic oxidation was elucidated as the non-radical pathway, and singlet oxygen was identified as the primary reactive species. Experiments on the influence of anions (5–500 mM) further show that the inhibiting effect was overcame due to the non-radical process. Interestingly, Cl− markedly facilitated the catalytic performance by generating HOCl in the catalytic process. The results highlight leveraging the non-radical pathway dominated by singlet oxygen to conquer the inhibitory effect of anions in NGC700/PMS system, which represents a crucial step towards environmental remediation under high salinity condition.

The world is facing many problems including that of traffic congestion. To highlight the issue of traffic congestion worldwide specially in urban areas and to make it more efficient, research community is working on Intelligent Transportation Systems (ITS). However, there is very limited work in security aspects of ITS which makes it less secure against increasing security threats. Most of the existing frameworks provide security services for ITS with many unrealistic assumptions. In this paper, we propose a Fog-based Security Framework for Intelligent Traffic Light Control System that provides security services with realistic assumptions. Moreover, the proposed framework is compared with a similar framework called secure intelligent traffic light control based on security, performance, and applicability in real world scenario. The results show that the proposed framework is more secure as compared to the existing secure intelligent traffic light control framework and realistic for real world scenario. The proposed framework possesses confidentiality, integrity, and authenticity features. The security features of the proposed framework are verified through the Automated Validation of Internet Security Protocols and Applications tool.

In this study, Multiwalled Carbon Nanotubes (MWCNTs) and Marble Powder (MP) have been utilized in reinforced concrete columns to assess their structural behavior. The nanotubes from 0.025% to 0.20% and 5% MP by weight of cement were used. The compressive strength of reinforced concrete columns and cubes was analyzed as the main property. The incorporation of MWCNTs and marble powder was able to increase the compressive strength of columns by 72.69% and mortar by 42.45% as compared to reference concrete. The ductility was noted to be improved by 42.04%. The load-deformation and stress-strain behaviors were also analyzed. The Scanning Electron Microscopy (SEM) analysis revealed the formation of a strong compact bridge (90–100 layers), Calcium Silicate Hydrate (C-S-H) gel, evenly dispersion, and bridging effect caused by MWCNTs. The incorporation of 0.20% MWCNTs by weight of cement was recommended to be effectively used as a reinforcing agent in concrete.

There is lot of research work at enhancing the performance of energy conversion and energy storage devices such as solar cells, supercapacitors, and batteries. In this regard, the low bandgap and a high absorption coefficient of CdSe thin films in the visible region, as well as, the low electrical resistivity make them ideal for the next generation of chalcogenide-based photovoltaic and electrochemical energy storage devices. Here, we present the properties of CdSe thin films synthesized at temperatures (below 100°C using readily available precursors) that are reproducible, efficient and economical. The samples were characterized using XRD, FTIR, RBS, UV-vis spectroscopy. Annealed samples showed crystalline cubic structure along (111) preferential direction with the grain size of the nanostructures increasing from 2.23 to 4.13 nm with increasing annealing temperatures. The optical properties of the samples indicate a small shift in the bandgap energy, from 2.20 to 2.12 eV with a decreasing deposition temperature. The band gap is suitably located in the visible solar energy region, which make these CdSe thin films ideal for solar energy harvesting. It also has potential to be used in electrochemical energy storage applications.

Clinical treatment of skin lesion is primarily dependent on timely detection and delimitation of lesion boundaries for accurate cancerous region localization. Prevalence of skin cancer is on the higher side, especially that of melanoma, which is aggressive in nature due to its high metastasis rate. Therefore, timely diagnosis is critical for its treatment before the onset of malignancy. To address this problem, medical imaging is used for the analysis and segmentation of lesion boundaries from dermoscopic images. Various methods have been used, ranging from visual inspection to the textural analysis of the images. However, accuracy of these methods is low for proper clinical treatment because of the sensitivity involved in surgical procedures or drug application. This presents an opportunity to develop an automated model with good accuracy so that it may be used in a clinical setting. This paper proposes an automated method for segmenting lesion boundaries that combines two architectures, the U-Net and the ResNet, collectively called Res-Unet. Moreover, we also used image inpainting for hair removal, which improved the segmentation results significantly. We trained our model on the ISIC 2017 dataset and validated it on the ISIC 2017 test set as well as the PH2 dataset. Our proposed model attained a Jaccard Index of 0.772 on the ISIC 2017 test set and 0.854 on the PH2 dataset, which are comparable results to the current available state-of-the-art techniques.

The interplay between melatonin (Mel) and calcium (Ca) in enhancing tolerance to metalloid toxicity and underlying physiological and biochemical mechanisms of this relationship still remains unknown. The present study reveals that the signaling molecules Mel and/or Ca enhanced tolerance of Vicia faba (cv. Tara) plant to metalloid arsenic (As) toxicity. However, a combination of Mel and Ca was more efficient than alone. Plants grew with As exhibited enhanced hydrogen peroxide, superoxide anion, electrolyte leakage, lipid peroxidation together with increased reactive oxygen species (ROS) producing enzymes, such as NADPH oxidase and glycolate oxidase (GOX). On the contrary, an inhibition in chlorophyll (Chl) biosynthesis and gas exchange parameters (net photosynthetic rate, stomatal conductance, intercellular carbon dioxide concentration) was observed. Under As toxicity conditions, the application of Mel and Ca synergistically suppressed the plants’ program cell death features (nucleus condensation and nucleus fragmentation) in guard cells of stomata, DNA damage, and formation of ROS in guard cells, leaves and roots. Moreover, it enhanced gas exchange parameters and activity of enzymes involved in photosynthesis process (carbonic anhydrase and RuBisco), Chl biosynthesis (δ-aminolevulinic acid dehydratase), and decreased activity of Chl degrading enzyme (chlorophyllase) under As toxicity conditions. Our investigation evidently established that expression of ATP synthase, Ca-ATPase, Ca-DPKase, Hsp17.6 and Hsp40 was found maximum in the plants treated with Mel + Ca, resulting in higher tolerance of plants to As stress. Also, increased total soluble carbohydrates, cysteine, and Pro accumulation with increased Pro synthesizing enzyme (Δ-pyrroline-5-carboxylate synthetase (P5CS) and decreased Pro degrading enzyme (proline dehydrogenase) in Mel + Ca treated plants conferred As toxicity tolerance. The obtained results postulate strong evidence that the application of Mel along with Ca enhances resilience against As toxicity by upregulating the activity of plasma membrane H-ATPase, enzymes involved in antioxidant system, and ascorbate-glutathione pathway., The authors extend their appreciation to the Deanship of Scientific Research at King Saud University for funding this work through Research Group No. RG-1441-438.

Clean Pakistan is a government campaign to keep the nationwide environment of the country clean. According to higher education commission (HEC) Pakistan report of 2014-2015, total number of students in universities was 1,295,178. Growing number of students in universities of Pakistan also create lots of garbage in universities. In result, the waste collection and garbage management in universities are a crucial issue to be concerned by the universities administrator. The major need of a managed and healthy university campus environment begins with cleanliness of classes, corridors offices and parks of campus and we can achieve this with the efficient management of garbage baskets of campus. A university campus waste will have managed more efficiently only if the garbage baskets are placed throughout the campus and collected well. The major issue in the traditional waste management system in most of the university campuses is the unhealthy and overflowing status. A solution is proposed to upgrade minor and important component of the university waste management system in this paper, which is garbage basket and its management. The basic idea of this project is to connect each garbage basket by using internet of things (IoT) protocol with main sweeper monitoring room for showing status of each basket and notify wirelessly.

Internet of Things (IoT) constitutes the next step in the field of technology, bringing enormous changes in industry, medicine, environmental care, and urban development. Various challenges are to be met in forming this vision, such as technology interoperability issues, security and data confidentiality requirements, and, last but not least, the network protocols. Network Connectivity is the backbone for Internet of Things as it dynamically affects the way how Internet of Things applications are designed. Currently, there are various standard system protocols which include Bluetooth LE, 3GPP, LTE, 6LoWPAN, ZigBee, IEEE 802.15.4. and they define how the physical objects, or the gadgets communicate with one another and to the cloud or to the gateway device. Further, there are loads of drivers for choosing the most appropriate remote convention, toward one side there is mechanical push to design imaginative arrangements and on the opposite side there show up client requests for improving the IoT applications. This paper proposes A network design space is proposed in this paper which uses the innovation and knowledge management techniques aimed to help the users to select a desired wireless protocol. The design is visualized into a three-dimension space where all the standard protocol options can be realized or studied based along these three axes – duty cycle, device to gateway distance and battery life. This paper proposes a design which is innovative with combinations of network protocols providing various choices in selecting the desired technology which is required by the applications of Internet of Things.

Smartphones with gym exercises predictors can act as trainers for the gym-goers. However, various available solutions do not have the complete set of most practiced exercises. Therefore, in this research, a complete set of most practiced 26 exercises was identified from the literature. Among the exercises, 14 were unique and 12 were common to the existing literature. Furthermore, finding suitable smartphone attachment position(s) and the number of sensors to predict exercises with the highest possible accuracy were also the objectives of the research. Besides, this study considered the most number of participants (20) as compared to the existing literature (maximum 10). The results indicate three key lessons: (a) the most suitable classifier to predict a class (exercise) from the sensor-based data was found to be KNN (K-nearest neighbors); (b) the sensors placed at the three positions (arm, belly, and leg) could be more accurate than other positions for the gym exercises; and (c) accelerometer and gyroscope when combined can provide accurate classification up to 99.72% (using KNN as classifier at all 3 positions).

This article comprises of the structural, magnetic, magneto-caloric and critical behavior study of single phase perovskite manganite LaMnO3+δ sample synthesized by traditional Solid State route. X-ray powder diffraction (XRD) at room temperature indicates the single phase trigonal crystalline structure of LaMnO3+δ with hexagonal setting R 3 ‾ c . Magnetic, magnetocaloric and critical behavior are studied using temperature dependent magnetization (M−T) and applied magnetic field dependent magnetization (M−H) data probed by Physical Property Measurement System (PPMS). The second order ferromagnetic to paramagnetic (FM-PM) phase transition is observe at Curie temperature (TC ∼ 180 K). This phase transition is responsible for maximum entropy change ( Δ S M max ) of 0.451(1) J/kg K at applied magnetic field of 6 Tesla with relative cooling power (RCP) of 54.293(5) J/kg. At TC, the order of magnetic phase transition is examined by employing Modified Arrott plots (MAP), Kouvel Fisher (KF) and simple isotherm analysis technique. The obtained values of critical exponent’s β ≈ 0.365 ± 0.06, γ ≈ 1.14 ± 0.04 and δ ≈ 4.16 ± 0.10 elaborate that the magnetic phase transition coordinated well with the 3D-Heisenberg model at TC ≈ 180 K and are confirmed by scaling equations of state. Similarly the change in magnetic entropy (ΔSM) versus applied magnetic field recorded complies with the power law ΔS = (H)n with n = 0.64 at TC = 180 K.

Polycrystalline La0.9Ba0.1MnO3 (LBMO) manganite samples are synthesized by usual solid state reaction technique. X-ray powder diffraction at room temperature indicates that our samples crystallize in the rhombohedral structure with an R 3 ¯ c space group. Magnetocaloric and critical behavior of the sample is probed through temperature and magnetic field dependent magnetization measurements. The compound shows paramagnetic-ferromagnetic (PM-FM) transition at critical temperature (TC) of 280 K and the nature of this transition is of second order. The deviation in the inverse of susceptibility versus temperature plot from Curie–Weiss law near TC unveiled the presence of Griffiths phase (GP) at TG = 292 K with susceptibility exponent λ = 0.3. The presence of Griffiths phase (GP) proves the existence of ferromagnetic clusters in the paramagnetic domain. Having second order phase transition sample shows a maximum magnetic entropy change (Δ S M m a x ) of 0.665 J/kg K for the magnetic field change of 4 Tesla. The sample also exhibits high relative cooling power (RCP) of 28.83 J/kg against this field. The critical behavior of second order phase transition in this sample is analyzed using Modified Arrott plots (MAP), Kouvel Fisher (KF) and critical isotherm analysis method. The estimated critical exponents of the sample are β ≈ 0.3, γ ≈ 1.32 and δ ≈ 5.1. These values of the critical exponents are also verified by scaling equations of state. Further the change in magnetic entropy (ΔSM) versus applied field obeys the power law ΔSM = (μoH) n with exponent value n = 0.55 at TC = 280 K.

Copper (Cu) nanoparticles and Cu0.5Tl0.5Ba2Ca2Cu3O10−δ (CuTl-1223) superconducting phase were synthesized by sol-gel and solid-state reaction, respectively. These metallic Cu nanoparticles were added in CuTl-1223 superconducting matrix to get (Cu)x/CuTl-1223; x = 0–4.0 wt% nanoparticles-superconductor composites and their temperature dependent magneto-transport properties were studied. The zero-field-cooled (ZFC) and field-cooled (FC) temperature dependent magnetization (M-T) measurements of (Cu)x/CuTl-1223 samples showed an increase in transition temperature and in amplitude of diamagnetic signal after the inclusion of Cu nanoparticles in the host CuTl-1223 matrix. The improvement in these magneto-transport properties can be attributed to the increase in number of efficient pinning centres in CuTl-1223 matrix after addition of Cu nanoparticles. Magnetization hysteresis (M-H) loops were obtained at various operating temperatures from which the magnetization critical current density (Jc) was estimated using Bean's critical state model. M-H loops indicated the combined superconducting and ferromagnetic behaviour up to 90 K in all (Cu)x/CuTl-1223 samples. Improvement in Jc could also be due to increase in number of pinning centres with addition of Cu nanoparticles in CuTl-1223 matrix. Maximum improvement in magneto-transport properties of (Cu)x/CuTl-1223 samples was observed for x = 1.0 wt%, which had specified the optimum content level of Cu nanoparticles in CuTl-1223 phase.

Different amounts of MgF2 were substituted in (1-x)BiScO3-xPbTiO3 (BS-PT) at x = 0.64. Magnesium as an acceptor was supposed to be incorporated at B-site and fluorine at anionic sites. Morphotrophic phase boundary (MPB) was found at 0.5% MgF2 doping where tetragonal and monoclinic phases coexisted in almost equal proportion. Tolerance factor as well as cationic displacements played important role in enhancing Tc. MgF2 doping enhanced Curie temperature (Tc) and electromechanical coupling factor (kp) up to 490 °C and 0.66, respectively. Grain size and porosity increased with doping amount due to fluorine. The dielectric loss was suppressed with MgF2 addition at room temperature.

Magnetic manganese ferrite (MnFe2O4) nanoparticles were synthesized by sol–gel method and solid-state reaction method was chosen for preparation of the superconducting Cu0.5Tl0.5Ba2Ca2Cu3O10−δ (CuTl-1223) phase. Superconducting-nanoparticles (MnFe2O4)x/CuTl-1223; x = 0–2.0 wt% composites were obtained by adding MnFe2O4 nanoparticles in CuTl-1223 superconducting matrix. The unchanged tetragonal crystal structure of the host CuTl-1223 superconducting phase witnessed that MnFe2O4 nanoparticles were not decomposed and settled at the grain-boundaries. The superconductivity was over all suppressed due to the reduction of superconducting volume fraction and enhanced scattering cross-section of the mobile charge carriers across these magnetic MnFe2O4 nanoparticles settled at the grain-boundaries of the host superconducting CuTl-1223 phase. The frequency dependent dielectric properties of (MnFe2O4)x/CuTl-1223 composites were probed at different operating temperatures. Different dielectric parameters (i.e. ɛ′r, ɛ″r, tanδ and σac) were determined from the experimentally measured capacitance (C) and conductance (G). The variation of these dielectric properties of CuTl-1223 superconducting phase with the variation of test frequency, contents of MnFe2O4 nanoparticles and operating temperature were investigated, correlated, compared and explained. These investigations can be very useful for the selection criteria of the materials for the practical applications.

Here in, we report the charge transport mechanism in semiconducting La0.5Ca0.5Mn0.5Fe0.5O3 (LCMFO) polycrystalline material synthesized via sol–gel auto combustion route. X-ray diffraction (XRD) analysis confirmed the orthorhombic phase of the prepared material. Temperature dependent resistivity and impedance spectroscopy measurements have been carried out to probe the dielectric and electrical conduction mechanism which revealed a change of Mott variable range to the small polaronic hopping conduction mechanism around 303 K. The complex impedance and modulus spectra undoubtedly showed the contribution of both grain and grain boundary effect on the conduction properties of LCMFO. An equivalent circuit [(RgbQgb) (RgQg)] model has been used to address the electrical parameters associated with the different phases (grains and grain boundaries) having different relaxation times. The values of resistances of two phases obtained after fitting the equivalent circuit in the nyquist plot have been analyzed which confirmed the change of conduction mechanism around 303 K. The resultant change in conduction mechanism is also supported by the conductivity plots.

Cobalt oxide (Co3O4) nanoparticles and Cu0.5Tl0.5Ba2Ca2Cu3O10-δ (CuTl-1223) superconducting phase were prepared by sol–gel and solid-state reaction methods, respectively. Co3O4 nanoparticles were added in CuTl-1223 superconducting matrix to get (Co3O4)x/CuTl-1223, x = 0–2.0 wt.%, nanoparticles–superconductor composites. The unchanged crystal structure of the host CuTl-1223 superconducting phase (i.e. tetragonal) revealed that Co3O4 nanoparticles were settled at the grain boundaries. Superconducting properties of the CuTl-1223 phase were overall suppressed due to hole–charge carriers interaction at the grain boundaries. The dielectric properties of (Co3O4)x/CuTl-1223 composites were investigated by varying the test frequencies from 40 Hz to 100 MHz and operating temperatures from 77 to 298 K. The values of dielectric properties were found maximal at lower frequencies and started to decrease at higher frequencies. So, the dielectric properties of the CuTl-1223 superconducting phase can be tuned by varying the contents of (Co3O4) nanoparticles, test frequencies as well as operating temperatures.

MgCo2O4 samples were synthesized by inverse co-precipitation method. The formation of a single-phase spinel structure was confirmed by X-ray diffraction measurements and Fourier-transform infrared spectroscopy. The samples crystallized in a face-centered cubic structure with Fd-3m space group as revealed from the Rietveld refinement of X-ray diffraction data. Magnetic measurements carried out in a broad temperature range of 5–300 K showed antiferromagnetic to paramagnetic phase transition (Neel temperature) observed at 101 K. Magnetic susceptibility data fitted using the Curie Weiss law and effective Bohr magnetic moment (μeff) for Co atoms was determined. Calculated μeff comes out to be 3.05 μB. These results were correlated to the spin states of Co3+ atoms. A small hysteresis in the field-dependent magnetization MH loop taken at 5 K indicates the existence of weak ferromagnetism in this system. The electrical resistivity measurement in the temperature range 77–750 K displayed the semiconducting-like behavior for this system.

We present an extensive study of the magnetic properties of a novel La0.5Ba0.5MnO3 perovskite material prepared by the hydrothermal method. The explored sample was structurally studied by the x-ray diffraction (XRD) method which confirms the formation of a pure cubic phase of a perovskite structure with Pm3m space group. The magnetic properties were probed by employing temperature M (T) and external magnetic field M (μoH) dependence of magnetization measurements. A magnetic phase transition from ferromagnetic to paramagnetic phase occurs at 339 K in this sample. The maximum magnetic entropy change ( $\left | {{\Delta } S}_{M}^{\max } \right |$ ) took a value of 1.4 J kg− 1 K− 1 at the applied magnetic field of 4.0 T for the explored sample and has also been found to occur at Curie temperature (TC). This large entropy change might be instigated from the abrupt reduction of magnetization at TC. The magnetocaloric effect (MCE) is maximum at TC as represented by M (μoH) isotherms. The relative cooling power (RCP) is 243.2 J kg− 1 at μoH = 4.0 T. Moreover, the critical properties near TC have been probed from magnetic data. The critical exponents δ, β, and γ with values 3.82, 0.42, and 1.2 are close to the values predicted by the 3D Ising model. Additionally, the authenticity of the critical exponents has been confirmed by the scaling equation of state and all data fall on two separate branches, one for T TC, signifying that the critical exponents obtained in this work are accurate.

Magnetoelectric composite of particular composition (0.5)PbZr0.52Ti0.48O3+(0.5)CoFe2O4 was synthesized by citrate–sol–gel method. Rietveld refinement of X-ray diffraction (XRD) pattern confirmed the presence of cubic spinel structure for CoFe2O4 and the coexistence of tetragonal along with a rhombohedral perovskite structure for PbZr0.52Ti0.48O3 in the prepared sample. Whereas, scanning electron micrograph (SEM) showed dense and homogeneous distribution of constituent phases. Temperature dependent dielectric measurements showed an abnormal frequency dependent behavior in the prepared composition, which is typically a characteristic of relaxor type materials. The observed behavior is explained in terms of structural disorders which give rise to alteration in the octahedron configuration in the PbZr0.52Ti0.48O3 phase that could promote the formation of the polar regions, which changes the dielectric properties of the prepared sample. Impedance spectroscopy was employed to understand the conduction mechanism which is found to be governed by small polaron hopping (SPH) mechanism. Moreover, it was found that the activations energies deduced from the conduction and relaxation process of constituent phases were comparable to each other. These results confirm that electric/dielectric properties and relaxation phenomenon are related to the similar origin.

Nd0.75Na0.25Mn1−xNixO3 (x = 0 − 0.07) were synthesized using a conventional solid-state synthesis method to investigate the effect of Ni substitution on their magnetic and electrical transport properties. XRD analysis using the Rietvield refinement method showed an increase in unit cell volume with increasing Ni content, indicating the possibility of substituting Ni for the Mn site. For x = 0, magnetization measurements showed paramagnetic (PM) to antiferromagnetic (AFM) transition at the transition temperature, TN ∼ 185 K, which may be related to the presence of charge-ordering (CO) state. For Ni-substituted samples, ferromagnetic (FM) to PM transition was induced with Curie temperature (TC), increasing from 91 K (x = 0.01) to 115 K (x = 0.03), followed by decreases in TC to 60 K (x = 0.07). Electrical resistivity measurements showed that samples for x ≤ 0.01 exhibited insulator behavior while both x = 0.03 and 0.05 samples exhibited metal-insulator transition suggesting that the CO state is weakened. For x = 0.07, the sample shows re-entrant of insulating characteristic. Inducement of FM metallic (FMM) state, as well as increased of TC for x = 0.03 is suggested to be related to FM SE between Ni2+ and Mn4+, which suppressed the CO state, hence inducing double-exchange (DE)-like mechanism. In addition, an increase in resistivity was observed as temperature decreased below the resistivity minimum (Rmin) at Tmin ∼ 40 K for x = 0.05 is possibly due to the Kondo-like effect mechanism. On one hand, the M(H) curve showed the presence of a hysteresis loop for x = 0 and 0.01 at T= 60 and 80 K, indicating the presence of an unstable phase, which may be related with the CO-AFM phase. For x = 0.03, no hysteresis loop was observed, indicating the suppression of the CO-AFM. Intriguingly, for x = 0.05 and 0.07, small hysteresis loop was observed, indicating the possible presence of a minor AFM component. Further, the observed MR behavior in present studies can be understood as a result of a decreased scattering mechanism in the presence of magnetic field.

Manganese ferrite (MnFe2O4) nanoparticles and Cu0.5Tl0.5Ba2Ca2Cu3O10−δ(CuTl-1223) superconducting phase were synthesized by sol-gel and solid-state reaction methods, respectively. Different contents of MnFe2O4 nanoparticles were added in CuTl-1223 superconducting matrix to get (MnFe2O4)x/CuTl-1223; x = 0∼2.0 wt% nanoparticles-superconductor composites. Complex electric modulus spectroscopy measurements of (MnFe2O4)x/CuTl-1223 composites were carried out at different test frequencies from 20 Hz to 10 MHz and at different operating temperatures from 78 to 253 K to analyze and interpret the dynamical aspects of electrical transport phenomena (i.e., such as carrier hopping rate, conductivity, and blocking factor). The complex electric modulus spectra showed the effects of both grains and grain-boundaries on electrical properties. The capacitance of grain-boundaries was found higher than that of grains. The capacitive behavior of grains was increased and that of grain-boundaries was decreased with increasing operating temperature for all these samples. Blocking factor of these composites was increased with increasing contents of MnFe2O4 nanoparticles. Shifting of peaks in imaginary part of modulus spectra towards lower frequency with increasing contents of these nanoparticles showed non-Debye type relaxation phenomenon in the material.

Electromagnetic spectrum is too cluttered to add additional broadband channels of high data rate and bandwidth. Free space optical (FSO) communication is one of the most dominant optical wireless communication systems, which provides huge and licensed free spectrum, non-interfering link, and high data rate. Despite of having above-mentioned advantages, the FSO links are very sensitive to bad weather conditions (i.e., fog, snow, dust, and their combination). Therefore, there is a dire requirement to develop a system that can overcome issues of individual communication system and adjust the current demand of new broadband channels. Adaptive FSO-radio frequency (RF) communication system is proposed to tackle the individual channel issues. A novel throughput maximization algorithm (TMA) is developed for the adaptive hybrid FSO-RF channel. Performance of the proposed algorithm for adaptive hybrid communication system is analyzed considering the regular and right-regular low density parity check (LDPC) code under various weather conditions. Simulation results show that the TMA performs well under all weather conditions and gives a performance gain of up to 2.25 dB considering the right-regular LDPC code. From the presented results, it is also seen that the suggested communication system optimizes mapping schemes, bit proportions for each channel, and puncturing ratios adaptively for different degree variable nodes in worst weather conditions.

Wireless multimedia sensor network has been renewed to the distributed model by incorporating the single board computer (i.e., camera nodes and mobile beacons). The redesigned camera nodes, such as unmanned aerial vehicle and mobile beacon nodes are limited in terms of memory, computation power, bandwidth, and node power while the real-time processing requires the multimedia contents transmission over the wireless interface in the presence of all these constraints. To tackle this problem, advanced video compression schemes have been adopted by which bit rate overhead over the network is greatly improved. H.264/moving picture experts group (MPEG)-4 is a state-of-the-art video compression standard developed jointly by International Telecommunication Union Telecommunication Standardization Sector video coding experts group and ISO/Joint Technical Committee of International Electrotechnical Commission MPEG. The H.264 provides a number of tunable parameters (e.g., quantization parameter (QP) and number of reference frames (NoRF)) for tailoring the encoding process as per requirements. In this paper, we propose a framework consisting of a joint parameter cost function to find the best trade-off between QP and NoRF with the policy of controlling the bit-rate (BR) while maintaining reasonably good video quality without compromising on processing delay (PD) and nodal power consumption (NPC). The framework has been proposed by transforming the multi-objective problem into a convex optimization problem. It is shown that an optimal trade-off between these conflicting objectives can be achieved by choosing appropriate values for QP and NoRF. Results for optimal values of QP and NoRF with corresponding trade-off between BR, quality of multimedia contents, low PD and low NPC are presented.

Ternary spinel chromite ZnCr2O4 was synthesized by sol-gel auto-combustion method. Rietveld profile analysis of X-ray powder diffraction data revealed the cubic spinel crystal structure with Fd-3 m space group. The dielectric relaxation and transport behavior of ZnCr2O4 were studied in detail by complex impedance spectroscopy in the frequency range of 70 - 1.1 x 10 6 H z over the measured temperature range of 293 - 523 K . Nyquist plots modeled by the equivalent circuit R G ‖ Q G + R G B ‖ Q G B indicated the presence of two relaxation processes in the material. The AC conductivity followed Jonscher power law and variation of frequency exponent with temperature depicted non-overlapping small polaron tunneling as a dominant electrical transport mechanism in the sample. Moreover, the DC conductivity obeyed Mott and Davis law. The frequency and temperature dependence of dielectric constant and loss factor was discussed in terms of space charge polarization, Maxwell-Wagner type dielectric relaxation and hopping of charge carriers between Cr2+ and Cr3+ networks in ZnCr2O4 system.

In the present work, the polycrystalline La0.7Bi0.3Fe0.5Mn0.5O3 maganite was synthesized by sol-gel auto-combustion method. The room temperature X-ray powder diffraction pattern confirmed the orthorhombic phase of the sample with pbnm space group. Frequency and temperature dependent electric modulus and impedance spectroscopic analyses revealed two electro-active components of the material characterized by highly resistive grain boundaries and comparatively conducting grains, respectively. The normalized scaling behavior of modulus plots divulged the temperature independence of the dynamic process in electro-active regions. The fitting of impedance data by the equivalent circuit (RG||QG) + (RGB||QGB) was applied to explore the physical parameters associated with grains and grain boundaries. The dispersion in dielectric permittivity and loss factor at lower frequencies attributed to the space charge polarization were observed. The electrical conductivity obeyed Mott’s T1/4 law and the slope of frequency dependent AC conductivity spectra changed due to multiple activation barriers and active traps, consistent with the variable-range hopping conduction in the material.

Herein, we have synthesized NiCr2O4 chromite by the sol-gel auto-combustion route. The refined X-ray powder diffraction pattern confirmed the single-phase formation of the material, which crystallized in a cubic normal spinel structure with space group Fd3m. The complex impedance study indicated the existence of relaxation phenomenon and predicted the semiconducting nature of the material. The frequency-dependent Nyquist plot modeled by (RGBCGB) (RGQG) equivalent circuit exhibited the effects of grain and grain boundary to the electrical response of the compound over the measured temperature range of 263 - 393 K. The experimental AC conductivity data followed Jonscher’s double power-law behavior, and the frequency exponent profile suggested small polaron hopping as the most probable transport mechanism for the sample. The complex modulus analysis showed the non-Debye type behavior of the material. In contrast, the dielectric constant exhibited dispersion in the low-frequency regime with a large tangent loss directly related to temperature.

The (Cu0.5Tl0.5)Ba2Ca3Cu4O12−δ thin films were synthesized at 895, 905 and 920 °C. These films are c-axis oriented and have shown tetragonal structure. The samples have been investigated for excess conductivity analysis. The analyses are carried out by following Aslamazov–Larkin theory. It is observed that the values of ξc(0), vF, λp.d, J decrease, but that of Bc(T), Bc1(T), Jc(0) increase with the increase of synthesis temperature. However, with the post-annealing of the samples at 100, 300 and 400 °C, the values of ξc(0), vF, τϕ and J increase but, the values of Bc(T), Bc1(T) and Jc(0) suppress with the increasing annealing temperature. It is proposed that with the higher synthesis temperature thallium defects are created in the charge reservoir layer that act as pinning centers whereas with post-annealing of the samples oxygen defects are removed. The former enhances whereas the later promotes suppression of Bc(T), Bc1(T), Jc(0) parameters in (Cu0.5Tl0.5)Ba2Ca3Cu4O12−δ thin films.

The reduction of charge carrier recombination and intrinsic defect density in organic–inorganic halide perovskite absorber materials is a prerequisite to achieving high-performance perovskite solar cells with good efficiency and stability. Here, we fabricated inverted planar perovskite solar cells by incorporation of a small amount of excess organic/inorganic halide (methylammonium iodide (CH3NH3I; MAI), formamidinium iodide (CH(NH2)2I; FAI), and cesium iodide (CsI)) in CH3NH3PbI3 perovskite film. Larger crystalline grains and enhanced crystallinity in CH3NH3PbI3 perovskite films with excess organic/inorganic halide reduce the charge carrier recombination and defect density, leading to enhanced device efficiency (MAI+: 14.49 ± 0.30%, FAI+: 16.22 ± 0.38% and CsI+: 17.52 ± 0.56%) compared to the efficiency of a control MAPbI3 device (MAI: 12.63 ± 0.64%) and device stability. Especially, the incorporation of a small amount of excess CsI in MAPbI3 perovskite film leads to a highly reproducible fill factor of ...

Aerosol assisted chemical vapour deposition (CVD) is a sophisticated, unique and modern technique which is used to deposit coatings, films, and other related structures from thermally unstable or the involatile precursors at laboratory and large scale productions. A light weight semiconducting and ceramic oxide based coatings on appropriate substrates can be produced at a lower cost by employing chemical vapour deposition method. There is broader choice of chemical precursors and their availability for obtaining high quality thin films at lower cost and the reaction environment is more flexible ranging from low pressure to atmospheric pressure in CVD. New ferrocene containingheterobimetallic precursor, [C 58 H 80 Fe 2 O 4 Sn 2 ] has been synthesized and characterized by elemental analysis, FT-IR spectroscopy, thermogravimetric analysis and molecular structure was determined by X-ray single crystal analysis. The heterobimetallic complex was used as a single-source precursor for the growth of iron tin oxide thin film by aerosol assisted chemical vapor deposition. The deposited thin film was characterized by X-ray diffractometer, scanning electron microscopy and atomic force microscopy techniques. The average roughness of deposited film at 425 °C from heterobimetallic precursor was in the range of 4.39 nm. The deposited thin film on glass strip was found to have no cracks, excellent adhesion and to be crystalline in nature and free from any carboneous impurities.

The oil and gas industry is plagued by inevitable formation damaged in the wellbore proximity during entire life of the well. Therefore, it is indispensable to ameliorate the damaged permeability by either using conventional applied techniques or ultrasonic-assisted stimulation method. The latter is characterized by efficient, simple and convenient, and environmentally secure method. Due to these distinguished characteristics, the demand of this physical Enhanced Oil Recovery (EOR) technique increased in petroleum industry. In this study, ultrasonic waves and hydrochloric acid (HCl) were used separately as well as in combination to recover the lost productivity caused by calcium carbonate (CaCO3) inorganic plugs in low permeability sandstone core samples. Results showed that permeability recovery increased with irradiation time up to 100 min; however, it decreased with further irradiation. This deviation could be due to particles bridge formation at later stage. In addition, optimum frequency and power of...

It is imperative to recover the well productivity lose due to formation damage nearby wellbore during variant well operations. Some indispensable issues in conventional techniques make ultrasonic technology more attractive due to simple, reliable, favorable, cost-effective, and environment friendly nature. This study proposes the independent and combined use of ultrasonic waves and chemical agents for the treatment of already damaged core samples caused by exposure to distilled water. Results elucidate that ultrasonic waves with optimum (20kHz, 1000W) instead of maximum frequency and power worked well in the recovery owing to peristaltic transport caused by matching of natural frequency with acoustic waves frequency. In addition, hundred minutes was investigated as optimum irradiation time which provided ample time span to detach fine loosely suspended particles. However, further irradiation adversely affected the damaged permeability recovery. Moreover, permeability improvement attributes to cavitation due to ultrasonic waves propagation through fluid contained in porous medium and thermal energy generated by three different ways. Eventually, experimental outcomes indicated that maximum (25.3%) damaged permeability recovery was witnessed by applying ultrasonic waves with transducer #2 (20kHz and 1000W) and optimum irradiation timeframe (100min). This recovery was further increased to 45.8% by applying chemical agent and optimum ultrasonic waves simultaneously.

Polycrystalline Pr 0.75 Na 0.25- x K x MnO 3 ( x = 0, 0.05, 0.10, 0.15 and 0.20) ceramics were prepared using conventional solid-state method and their structural, magnetic and electrical transport properties were investigated. Magnetization versus temperature measurements showed un-substituted sample exhibited paramagnetic behavior with charge-ordered temperature, T CO around 218 K followed by antiferromagnetic behavior at transition temperature, T N ∼ 170 K. K + -substitution initially weakened CO state for x = 0.05–0.10 then successfully suppressed the CO state for x = 0.15–0.20 and inducing ferromagnetic-paramagnetic transition with Curie temperature, T C increased with x . In addition, deviation of the temperature dependence of inverse magnetic susceptibility curves from the Curie-Weiss law suggests the existence of Griffiths phase-like increased with x . Magnetization versus magnetic field curves show existence of hysteresis loops at T x = 0) and T x = 0.05–0.10), which related to metamagnetic transition occurring at critical field. Electrical resistivity measurements showed an insulating behavior for x = 0 sample while for x = 0.05–0.20 samples showed metal-insulator transition and transition temperature, T MI increased with x . The increased in T C and T MI are attributed to the increase in tolerance factor which indicates reduction in MnO 6 octahedral distortion consequently enhanced double exchange interaction.

Mobile cloud computing requires specialized application development models that can facilitate development of cloud-enabled applications. This paper presents a mathematical model to calculate the computation offloading cost (time and energy consumption) of mobile cloud application models to facilitate in the development of mobile cloud computing simulators. It demonstrates the usage of the proposed model, and shows the impact of the cost incurring parameters on the overall computational time and energy consumption of the applications. The proposed model can assist cloud-powered applications to make context-aware offloading decisions and facilitate the development of mobile cloud computing simulators, which unfortunately, does not exist to date.

Manganese ferrite (MnFe 2 O 4 ) nanoparticles and Cu 0.5 Tl 0.5 Ba 2 Ca 2 Cu 3 O 10-δ (CuTl-1223) superconducting phase were prepared by sol-gel and solid-state reaction methods, respectively. MnFe 2 O 4 nanoparticles were added in CuTl-1223 matrix to get (MnFe 2 O 4 ) x /CuTl-1223 (x = 0 ∼ 2.0 wt.%) nanoparticles–superconductor composites. Different experimental techniques like XRD, SEM, R-T measurements and Impedance spectroscopy were used to characterize these composites. It was observed that crystal structure of host CuTl-1223 phase remained unaltered after addition of MnFe 2 O 4 nanoparticles, which indicated about the occupancy of these nanoparticles at grain-boundaries. Over all decreasing trend in superconducting properties may be attributed to spin-charge reflection and trapping of charge carriers across these magnetic MnFe 2 O 4 nanoparticles at grain-boundaries of CuTl-1223 phase. In complex impedance spectroscopy (CIS), role of MnFe 2 O 4 nanoparticles at the grain-boundaries of host CuTl-1223 phase was also investigated. The decrease in impedance (Z) with increasing temperature witnessed the occurring of thermally activated processes in the system. Higher value of activation energy at grain-boundaries showed that grain-boundaries are more resistive than grains due to non-stoichiometric distribution of oxygen and dangling bonds at grain-boundaries. The impedance master curves indicated that the distribution of relaxation time (dynamic process) is nearly temperature independent. The decrease in ac-conductivity with increasing content of these nanoparticles indicated the enhancement of space charges at grain-boundaries.

Perovskite manganites with chemical formula La0.5Ba0.5MnO3 (LBMO) samples were synthesized though the hydrothermal process by heating suitable reactants at 270 °C in an autoclave for 25 h. After washing with de-ionized water several times, the as prepared samples were then calcined at different temperatures, ranging from 120 to 1000 °C to remove the impurities. Final sintering of the sample was carried out at 1350 °C for 24 h. Subsequent X-ray diffraction (XRD) measurements were also carried out. Rietveld refinement of XRD data for the sample sintered at 1350 °C confirmed single phase cubic structure with lattice parameter a = 3.9057Ǻ and space group P m −3 m. The dc electrical measurements were performed in a broad range of temperatures from 77 to 870 K on this sample. The focal point of this study was to obtain microscopic parameters and characteristic length in order to discuss the relationship between magnetic, electric and phonon excitations. The electrical resistivity measurements revealed a metallic/ferromagnetic to semiconductor/paramagnetic phase transition (TC) at 339 K. In the metallic region the experimental data best fitted the resistivity equation $$\uprho (\text{T})={\uprho _{o}}+{\uprho _2}{\text{T}^2}+{\uprho _{2.5}}{\text{T}^{2.5}}+{\uprho _{4.5}}{\text{T}^{4.5}}$$ showing that the resistivity effect arises due to residual impurities, grain boundaries, electron–electron (e–e), electron–magnon (e–mag) and electron–phonon (e–ph) scattering. The analysis of the resistivity data above TC has shown a transformation in conduction mechanism from Mott’s variable range hopping (MVRH) to small polaron hopping (SPH), around 585 K. Hopping of carriers to larger distances with multiplying values of activation energies are analyzed through MVRH below 585 K. Above 585 K, the carriers were found to be trapped by several scattering centers through small polaron, this behavior having been interpreted in the light of SPH model.

A facile chemical precipitation method for slab and flower like WO3 microstructure having three-dimensional (3D) architecture is reported. The as-prepared WO3 powder specimens were characterized by X-ray diffraction (XRD) combined with Rietveld refinements, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy and UV–vis spectroscopy. SEM and XRD results revealed that the hierarchical WO3 microstructures with uniform flower-like morphology are congregated by number of interleaving nanosheets which have thickness of 150–180 nm and are crystallized in a single monoclinic WO3 phase. Thermo-gravimetric analysis shows a major weight loss of 8% due to evaporation of adsorbed water. The impedance spectroscopy of compact WO3 pellets showed that all samples were semiconducting with a minute difference in electrical properties. The photo-catalytic activity of the as-prepared WO3 samples was evaluated by the degradation of Rhodamine B (RhB) under ultra-violet light irradiation. The results showed that 3D hierarchical architectures exhibits high photo-catalytic efficiency compared with the slab like structure due to their porous hierarchical structures. The optical band gap energy of slab like structure is found to be lowered compared to flower-like WO3 structures. These tunable optical and transport features allow the development of new materials for potential applications as photo-catalysts, transparent conducting electrodes, electrochromic and sensor devices.

In the new era, the demand of bandwidth hungry applications is increasing day by day. In the similar manner, it is going to be unfeasible for the electromagnetic spectrum to adjust the latest broadband channels. Free-space optical (FSO) communication is one of the most dominant optical wireless communication (OWC) systems which not only provides the huge bandwidth, it provides licence-free spectrum as well. The FSO link connectivity problems due to the varying nature of weather can be overcome by using a parallel radio channel to the FSO. A hybrid optical/radio communication system is proposed with the assumption of Gamma-Gamma fading distribution for the FSO and Rician distribution for the radio channel. The proposed communication system is optimized by maximizing the total mutual information (MI) under all weather conditions (e.g., rain, fog and cloud). The optimization is done over the modulation and the joint power. The mapping schemes of the respective channel are optimally selected to maximize the MI while allocating the optimum power to each channel. Simulation results show that the proposed system always provides best MI under varying weather, i.e., both for the FSO and radio channel.