Lifetime Ratio Research Articles

Hybrid fuzzy logic and artificial Flora optimization algorithm-based two tier cluster head selection for improving energy efficiency in WSNs

Wireless Sensor Network (WSN) is the one of the hot area of research in which energy stability and network lifetime are considered to be the twin challenges during its application. Clustering is the optimum energy efficiency strategy that organizes the sensor nodes into potential groups for the objective of attaining energy stability and network lifetime. In this energy potent clustering process, cluster head selection is determined to be highly significant in order to balance energy among the nodes sensor nodes. Moreover, two-tier cluster head selection that includes temporary and final cluster head is identified to be challenging in WSNs. In this paper, Hybrid Fuzzy Logic and Artificial Flora Optimization Algorithm (FL-AFA)-based Two Tier Cluster Head Selection is proposed for improving energy efficiency and prolog network lifetime. This FL-AFA scheme achieved the cluster head selection in two stages, such as, i) Temporary Cluster Head (TCH) selection using FL and, ii) Final Cluster Head (FCH) selection using AFA. In the first stage, the concept of fuzzy logic applied over the input parameters of residual energy (RE), distance to BS (DTBS), and node degree (NDE). In the second stage, the benefits of AFA is employed for computing the fitness function through distance to nearby nodes (DNN), cluster compactness estimation factor (CCEF), and position estimation (PE). Simulation experiments of the proposed FL-AFA scheme and the benchmarked schemes are conducted based on the evaluation metrics of energy efficiency, network lifetime, average delay, and packet delivery ratio (PDR) under the impact of different sensor nodes. .

Lifetime ratio improvement technique using special fixed sensing points in wireless sensor network

Purpose The purpose of this paper is to improve the lifetime ratio of wireless sensor networks for maintaining the battery level at a desired point for better improvement of network health. Design/methodology/approach Sensor point network (SPN) is used for variety of applications like weather check, tracking of undesirable vehicles and delivery of data to end points. The proposed special high health sensing point (SHHSP) scheme will overcome several limitations of existing game theory approaches with respect to delay, health and overall throughput. Findings The simulation results of the proposed SHHSP scheme confirms the excellence over the existing works examined with respect to delay, hops, energy consumed, nutrition SP, harmful SP, throughput and overhead. Practical implications It is proposed for a smart communication system in IoT, where in the communication between the sensing point network to its neighbouring sensing network is carried out by selection of SHHSP, this is implemented by using the remaining energy and distance vector with respect to control station. The system is applicable to weather check and can also be used in tracking of vehicles in a vehicle ad hoc networks. Originality/value It is subsidized to the IoT system and vehicle-to-vehicle communication system where in the safety is of utmost concern. The system is concentrated on the battery concern of SPN in a pool of SPNs.

Thermally induced generation of platicons in optical microresonators.

We demonstrate a numerically novel mechanism providing generation of the flat-top solitonic pulses, platicons, in optical microresonators at normal group velocity dispersion (GVD) via negative thermal effects. We found that platicon excitation is possible if the ratio of the photon lifetime to the thermal relaxation time is large enough. We show that there are two regimes of the platicon generation depending on the pump amplitude: the smooth one and the oscillatory one. Parameter ranges providing platicon excitation are found and analyzed for different values of the thermal relaxation time, frequency scan rate, and GVD coefficient. Possibility of the turn-key generation regime is also shown.

Structure, first-principles calculations and yellow spectral properties of Dy3+: CaLaGa3O7 single crystal

High optical quality Dy3+-doped CaLaGa3O7 (abbreviated as Dy: CLGO below) crystal was grown successfully by the Czochralski technique along the (0 0 1) orientation. The lattice parameters of the as-grown crystal were obtained by Rietveld refinement to its XRD pattern. The electronic structures including band structure and density of state (DOS) were calculated by using first-principles calculations based on density functional theory (DFT). The spectroscopic characteristics of Dy: CLGO are investigated, with special attention to the yellow emission that could be pumped directly by the rapidly developed blue GaN LD. Based on the Judd-Ofelt (J-O) theory, the intensity parameters from the measured line strengths were determined. The J-O parameters were used to predict radiative transition probabilities, radiative lifetime and branching ratios for various excited levels of the Dy: CLGO crystal. The absorption cross-sections of Dy: CLGO at 453 nm are calculated to be 0.14 × 10−20 cm2 and 0.11 × 10−20 cm2 for π- and σ-polarizations, respectively. Meanwhile, Dy: CLGO exhibits strong yellow emission at 574 nm corresponding to the transition 4F9/2 → 6H13/2 with stimulated emission cross-sections of 3.88 × 10−21 cm2 and 3.42 × 10−21 cm2 for π- and σ-polarizations, respectively. The relatively long fluorescence lifetime (565 μs) indicates a high laser efficiency of the crystal. All results suggest that Dy: CLGO crystal could be a promising candidate for yellow laser at 574 nm pumped by blue GaN LD.

Investigation of photoluminescence and dielectric properties of europium-doped LaOCl nanophosphor and its Judd–Ofelt analysis

Present Phosphor La1−xEuxOCl (0 ≤ x ≤ 0.09) was synthesized via conventional solid-state method at a temperature of 700 °C for a duration of 2 h. The compound crystallized in the tetragonal structure with space group P4/nmm (No. 129). The intensity of transition 5D0 → 7F2 (617 nm) was found to be more intense in the photoluminescence spectra. Intensity parameters and radiative properties like radiative lifetime, transition probabilities, and branching ratio are evaluated employing of the Judd–Ofelt theory. At room temperature for a frequency range of 10 Hz—8 MHz, AC conductivity, dielectric properties of La1−xEuxOCl (0.01 ≤ x ≤ 0.09) are studied. Studies indicate that above 30 kHz till100 kHz, the AC conductivity establishes slowly and at 300 kHz increases rapidly. Greater values of dielectric constant and loss were exhibited towards lower frequencies which then declined significantly with increasing frequency making the phosphor suitable for microwave device applications. The CIE color coordinates results of Eu3+-activated LaOCl phosphor (0.642, 0.358) were closer to the commercial red phosphors such as Y2O3:Eu3+(0.645, 0.347), Y2O2S:Eu3+ (0.647, 0.343) and National Television System Committee (NTSC) (0.67, 0.33) resulting in making LaOCl:Eu3+behaves as a promising material for red phosphor materials.

Mobility-prediction and energy optimization for multi-channel multi-interface ad hoc networks in the presence of location errors

We present a mobility-prediction and energy optimization solution for multi-channel multi-interface (MCMI) ad hoc networks in the presence of location errors. This solution includes routing of the MCMI communication links that adapt to dynamic channel, traffic conditions, interference and mobility of nodes. We start first with implementing a novel cross-layer routing solution in order to share information between network and MAC layer, the benefit of this technique is to collect information about the channel quality and residual energy of the nodes and send them directly to the network layer. Next, we present a mobility-prediction model using Kalman filter to predict accurate locations and enhance routing performance, through estimating link duration and selecting reliable routes. The performance of proposed mechanism is measured using NS2.35 simulations with different scenarios and varying load in a network. Comparative analysis of simulation results shows better performance of our protocol (ME-MCMI AODV) in terms of reducing end-to-end delay, total dropped packets and increasing network lifetime and packet delivery ratio (PDR).

Energy efficient and link reliable routing (E2LR) scheme for underwater sensor networks

Underwater Sensor Network (USN) is the wireless network infrastructure applicable in deep ocean to detect, collect, and transmit information to a remote data acquisition location on shore. Underwater routing protocols are used to provide route information in addition to ensuring efficient data and information collection and transmission. Some routing strategies for USNs are linked to high energy consumption, high end-to-end delay and shorter network lifetime. These issues are due to unnecessary packet flooding especially during route establishment, improper selection of next hop neighbor and frequent communication for route maintenance. Considering these challenges, this paper presents a localization free energy efficient and link reliable (E2LR) routing protocol that controls unnecessary flooding of hello packets to reduce energy consumption in the information distribution phase. Further, E2LR calculates the link quality using a composite metric for next hop selection which ultimately reduces end-to-end delay and regularly updates the energy status in order to achieve optimization during routing operations. Simulation results show that E2LR exhibit higher performance than both H2-DAB and R-ERP2R in terms of energy efficiency during information distribution phase and data forwarding phase. Moreover, E2LR also shows superior performance regarding end-to-end delay, network lifetime and packet delivery ratio than compared protocols.

Does time heal all wounds? Life course associations between child welfare involvement and mortality in prospective cohorts from Sweden and Britain.

Child welfare involvement reflects childhood adversity and is associated with increased adult mortality, but it remains unclear how this association changes over the life course. Drawing on the Stockholm Birth Cohort Multigenerational Study (Sweden) and the National Childhood Development Study (Great Britain) this study examines whether inequalities within these cohorts diverge or converge. Involvement with child welfare services (ICWS) is divided into two levels (‘child welfare contact’ and ‘out-of-home care’). For each cohort, we quantify absolute health inequalities as differences in cumulative probabilities of death (18–58 years) and temporary life expectancy; and relative inequalities as hazard ratios in ten-year intervals and ratios of lifetime lost. Persistently, ICWS was associated with premature mortality. The strength of the association varied by age, sex and level of ICWS. Consistently across both countries, the most robust relationship was between out-of-home care and mortality, with statistically significant age-specific hazard ratios ranging between 1.8 and 3.4 for males and 1.8–2.1 for females. Child welfare contact that did not result in out-of-home placement showed less consistent results. Among females the mortality gap developed later compared to males. Estimates attenuate after controlling for family socioeconomic and other background variables but patterns remain intact. Our results show that absolute inequalities widen with increasing age, while relative inequalities might peak in early adulthood and then stabilize in midlife. The relative disadvantage among looked-after children in early adulthood is heightened by overall low rates of mortality at this age. Absolute inequality increases with age, highlighting the weight of the accumulation of disadvantage in mortality over time. The bulk of excess deaths that could be attributed to ICWS occurs from midlife onwards. Mechanisms that uphold the disadvantage after childhood experiences require further exploration. This study highlights that the association between out-of-home care and premature mortality seems to transcend welfare systems.

Impact of ΔEST on Delayed Fluorescence Rate, Lifetime, and Intensity Ratio of Tetrahedral Cu(I) Complexes: Theoretical Simulation in Solution and Solid Phases.

Profound understanding of the luminescence mechanism and structure-property relationship is vital for Cu(I) thermally activated delayed fluorescence (TADF) emitters. Herein, we theoretically simulated luminescent behavior in both solution and solid phases for two Cu(I) complexes and found the following: (i) The strengthened spin-orbit coupling (SOC) effect by more dx2-y2 orbital contributions and well-restricted structural distortion via remarkable intramolecular interaction in [Cu(dmp)(POP)]+ enable the emission at room temperature to be a mixture of direct phosphorescence (10%) and TADF (90%). (ii) Benefiting from enhanced steric hindrance and the electron-donating ability of the paracyclophane group, the narrowed S1-T1 energy separation (ΔEST) in [Cu(dmp)(phanephos)]+ accelerates the reverse intersystem crossing, promoting the TADF rate (1.88 × 105 s-1) and intensity ratio (98.3%). These results indicate that the small ΔEST is superior for reducing the lifetime and that the strong SOC stimulates the phosphorescence to compete with TADF, which are both conducive to avoiding collision-induced exciton quenching and reducing the roll-off in devices.

Tuning radiative lifetimes in semiconductor quantum dots.

Photonic devices stand to benefit from the development of chromophores with tunable, precisely controlled spontaneous emission lifetimes. Here, we demonstrate a method to continuously tune the radiative emission lifetimes of a class of chromophores by varying the density of electronic states involved in the emission process. In particular, we examined the peculiar composition-dependent electronic structure of copper doped CdZnSe quantum dots. It is shown that the nature and density of electronic states involved with the emission process is a function of copper inclusion level, providing a very direct handle for controlling the spontaneous lifetimes. The spontaneous emission lifetimes are estimated by examining the ratios of emission lifetimes to absolute quantum yields and also measured directly by ultrafast luminescence upconversion experiments. We find excellent agreement between these classes of experiments. This scheme enables us to tune spontaneous emission lifetimes by three orders of magnitude from ∼15 ns to over ∼7 µs, which is unprecedented in existing lumophores.

An energy‐efficient clustering and cross‐layer‐based opportunistic routing protocol (CORP) for wireless sensor network

SummaryEnergy‐efficient data collection is a significant research challenge in wireless sensor networks (WSNs). One of the essential approaches to improve WSN performance is clustering, routing, and denoising technique. Cluster head (CH) selection is an essential issue in WSN. The present work proposes cross‐layer‐based opportunistic routing protocol (CORP) for WSN. The proposed CORP approach has been used to find an optimal traversal path, which reduces computation time and energy consumption as well as improves data delivery reliability. For optimal clustering, K‐medoid with adaptive Harris hawk optimization algorithm (AHHO) has been utilized for clustering the sensor nodes. Quality of service (QoS) impact, energy status criteria, distance, and sensor nodes position have been considered as key factors. These factors can influence the selection of CH in WSN. Moreover, the CH selection method can minimize traffic and energy saving. For efficient data collection, a hybrid Variable Weighted stacked Autoencoder with adaptive sunflower optimization (VWAE‐ASFO) denoising technique has been intended for reducing the data error rate. Initially, in the data collection phase, the variable weighted stacked autoencoder senses the data and collects all the data from the network. Adaptive sunflower optimization algorithm (ASFO) updates the weight of VWAE to minimize the data error and model complexity. The simulation results demonstrate that the proposed CORP approach enhances QoS performance metrics such as energy consumption, packet delivery ratio, packet delay, network lifetime, throughput, jitter, buffer occupancy, and packet loss ratio. When the performance of the proposed approach is compared with the existing algorithms such as HEED, TCBDGA, FRLDG, MOBFO‐EER, and FEEC‐IIR, the proposed approach outperforms them.

Concentration dependent neodymium doped oxy fluoroborate glasses for 1.08 μm laser applications

Different concentrations of neodymium-doped (Nd3+ ions) Oxy Fluoroborate (OFB) glasses were fabricated and systematically analyzed by employing spectroscopic techniques such as optical absorption, photoluminescence (PL) and PL decay spectral measurements to understand the NIR lasing potentialities. The information pertaining to absorption spectral features were subjected to Judd-Ofelt (J-O) analysis to understand the radiative properties such as transition probability (AR), radiative lifetime (τR) and branching ratios (βR) possessed by the as prepared Nd3+ ions doped OFB glasses. By correlating the radiative properties with the emission and PL decay spectral profiles, the emission cross-sections (σse) and quantum efficiency values are evaluated for the prominent fluorescent levels of Nd3+ ions in the as prepared glasses. Under 808 nm diode laser excitation, all the OFB glasses under investigation showcased two prominent NIR emissions at 1085 nm (4F3/2 → 4I11/2) and 1328 nm (4F3/2 → 4I13/2). The intensities of both the emission peaks escalates with increases in Nd3+ ions concentration up to 1 mol% and beyond decreases showcasing concentration quenching. The experimental lifetime values estimated from the single exponential PL decay profiles of 4F3/2 level are decreasing monotonously with increase in Nd3+ ions concentration in the as prepared OFB glasses. Relatively higher branching ratios, emission cross-sections and quantum efficiency values estimated for Nd3+ ions doped OFB glasses indicates the potential usage of the as prepared glasses for 1.08 μm laser applications.

Energy-Aware Clustering and Efficient Cluster Head Selection

Abstract Clustering is an efficient technique to organize network resources efficiently and, in wireless sensor Networks (WSNs) communications it is used to group sensors with similar characteristics managed by a selected sensor called a Cluster Head (CH). Thus, this paper presents a new approach, namely Energy-Aware Clustering and Efficient Cluster Head Selection (EAC-ECHS) to optimize the performances of WSNs in terms of the network lifetime and enhance energy consumption. In EAC-ECHS, the sensor network is divided into an inter grid and fair clustered Grids. Furthermore, for each clustered Grid, the CH selection is based on the residual energy of sensor, distance to neighbors, and distance to the base station. Simulation experiments have been conducted to examine the performance of EAC-ECHS and previous approaches, and the results demonstrate that EAC-ECHS approach achieves the design objectives in terms energy consumption, network lifetime, and packet delivery ratio.

Adaptive Power Control Aware Depth Routing in Underwater Sensor Networks

Underwater acoustic sensor network (UASN) refers to a procedure that promotes a broad spectrum of aquatic applications. UASNs can be practically applied in seismic checking, ocean mine identification, resource exploration, pollution checking, and disaster avoidance. UASN confronts many difficulties and issues, such as low bandwidth, node movements, propagation delay, 3D arrangement, energy limitation, and high-cost production and arrangement costs caused by antagonistic underwater situations. Underwater wireless sensor networks (UWSNs) are considered a major issue being encountered in energy management because of the limited battery power of their nodes. Moreover, the harsh underwater environment requires vendors to design and deploy energy-hungry devices to fulfil the communication requirements and maintain an acceptable quality of service. Moreover, increased transmission power levels result in higher channel interference, thereby increasing packet loss. Considering the facts mentioned above, this research presents a controlled transmission power-based sparsity-aware energy-efficient clustering in UWSNs. The contributions of this technique is threefold. First, it uses the adaptive power control mechanism to utilize the sensor nodes’ battery and reduce channel interference effectively. Second, thresholds are defined to ensure successful communication. Third, clustering can be implemented in dense areas to decrease the repetitive transmission that ultimately affects the energy consumption of nodes and interference significantly. Additionally, mobile sinks are deployed to gather information locally to achieve the previously mentioned benefits. The suggested protocol is meticulously examined through extensive simulations and is validated through comparison with other advanced UWSN strategies. Findings show that the suggested protocol outperforms other procedures in terms of network lifetime and packet delivery ratio.

MicroRNA Based Feedforward Control of Intrinsic Gene Expression Noise.

Intrinsic noise, which arises in gene expression at low copy numbers, can be controlled by diverse regulatory motifs, including feedforward loops. Here, we study an example of a feedforward control system based on the interaction between an mRNA molecule and an antagonistic microRNA molecule encoded by the same gene, aiming to quantify the variability (or noise) in molecular copy numbers. Using linear noise approximation, we show that the mRNA noise is sub-Poissonian in case of non-bursty transcription, and exhibits a nonmonotonic response both to the species natural lifetime ratio and to the strength of the antagonistic interaction. Additionally, we use the Chemical Reaction Network Theory to prove that the mRNA copy number distribution is Poissonian in the absence of spontaneous mRNA decay channel. In case of transcriptional bursts, we show that feedforward control can attenuate the super-Poissonian gene-expression noise that is due to bursting, and that the effect is more considerable at the protein than at the mRNA level. Our results indicate that the strong coupling between mRNA and microRNA in the sense of burst stoichiometry and also of timing of production events renders the microRNA based feedforward motif an effective mechanism for the control of gene expression noise.

Role of TeO2 coordination with the BaF2 and Bi2O3 on structural and emission properties in Nd3+ doped fluoro phosphate glasses for NIR 1.058 μm laser emission

Fluoro phosphate glasses with different contents of barium and bismuth (8, 11, 14, 17 and 20 mol %) doped with Nd 3+ were prepared by melt quenching technique. Importance of these modifier ions on structural transformation were carried out using XRD, FTIR, FT-Raman and 31 P MAS NMR characterizations. 31 P MAS NMR spectra revealed that structural modifications due to Bi 2 O 3 are more when compared with BaF 2 in this fluoro phosphate glass matrix. Three phenomenological Judd-Ofelt (J-O) parameters Ω λ (λ = 2, 4, 6) have been derived from the absorption spectra of Nd 3+ doped barium and bismuth fluoro phosphate glasses. From the Judd-Ofelt parameters, transition probabilities (A), branching ratios (β) of certain transitions and radiative lifetimes of certain excited states of Nd 3+ are extracted and reported. From the emission spectra, emission cross sections (σ e ), band gains (σ e xΔλ eff ) and optical gain parameters (σ e xτ R ) were reckoned for the observed emission bands in these phosphate glasses. It is observed that barium glass resulted higher laser spectroscopic parameters (σ e , σ e xΔλ eff , σ e xτ R ) which are crucial characteristics for exploring promising laser applications. Impact of Ba 2+ and Bi 3+ on luminescent properties of Nd 3+ doped fluoro phosphate glasses has been examined in search of solid sate gain medium for laser emitting NIR light around 1.058 μm for photonic applications. •Nd 3+ doped barium and bismuth flouro phosphate glasses are prepared by melt quenching technique. •Structural analysis for present fabricated vitreous material with the help of FT-Raman, FTIR and 31 P NMR spectra. •Addition of Alkaline earth fluoride BaF 2 enhance the spectroscopic properties. •The Nd 3+ doped Barium flouro phosphate glasses could be promising host in the NIR region around 1.058 μm.

Performance improvement of P3HT nanowire-based organic solar cells by interfacial morphology engineering

Poly (3-hexylthiophene-2,5-diyl) nanowires (nw-P3HT) have been a great interest for organic electronics, including organic field-effect transistors, organic photodetectors, organic photovoltaics, etc due to easy formation in the solution process. Thus both explanations of charge transport dynamics and morphology are crucial for device performance. Here we demonstrated the optoelectronic properties of the P3HT nanowires where the polymer backbones were parallel to the nanowire axis. The nanowires tended to form a bundle due to van der Waals interactions. Nanowire bundles were separated by 1,8-diiodooctane (DIO) additive for photovoltaic fabrication. The bundle separation was visualized by atomic force microscopy. The charge transfer mechanism was evaluated by electrochemical impedance spectroscopy. The electrical analysis showed that short-circuit current density (J sc) increases to 10.74 mA cm−2 after the bundle separation. According to impedance analysis, there is a correlation between effective lifetime and DIO ratio. These findings were considered as promising results for improving the transport by forming pathways for charge carriers.

Improving the performance of opportunistic routing using min-max range and optimum energy level for relay node selection in wireless sensor networks.

Opportunistic routing is an emerging routing technology that was proposed to overcome the drawback of unreliable transmission, especially in Wireless Sensor Networks (WSNs). Over the years, many forwarder methods were proposed to improve the performance in opportunistic routing. However, based on existing works, the findings have shown that there is still room for improvement in this domain, especially in the aspects of latency, network lifetime, and packet delivery ratio. In this work, a new relay node selection method was proposed. The proposed method used the minimum or maximum range and optimum energy level to select the best relay node to forward packets to improve the performance in opportunistic routing. OMNeT++ and MiXiM framework were used to simulate and evaluate the proposed method. The simulation settings were adopted based on the benchmark scheme. The evaluation results showed that our proposed method outperforms in the aspect of latency, network lifetime, and packet delivery ratio as compared to the benchmark scheme.

Crux of Using the Cascaded Emission of a Three-Level Quantum Ladder System to Generate Indistinguishable Photons.

We investigate the degree of indistinguishability of cascaded photons emitted from a three-level quantum ladder system; in our case the biexciton-exciton cascade of semiconductor quantum dots. For the three-level quantum ladder system we theoretically demonstrate that the indistinguishability is inherently limited for both emitted photons and determined by the ratio of the lifetimes of the excited and intermediate states. We experimentally confirm this finding by comparing the quantum interference visibility of noncascaded emission and cascaded emission from the same semiconductor quantum dot. Quantum optical simulations produce very good agreement with the measurements and allow us to explore a large parameter space. Based on our model, we propose photonic structures to optimize the lifetime ratio and overcome the limited indistinguishability of cascaded photon emission from a three-level quantum ladder system.

MIPSOE – Markov Integrated PSO Encryption Algorithm for Secure Data Aggregation

Various clustering algorithm exists in Wireless Sensor Networks concerned on balancing energy utilization. Many research issues deviate towards the formation of clusters based on energy, distance, and another sensor node’s resource parameters. In this article, the proposed protocol is composed of two phases. In the first phase, clusters are formed based on Particle Swarm Optimization and Markov’s Random Field mathematical calculation. The second phase generates a key, where the secret key is used for encryption technique. The proposed protocol is implemented in the NS2 simulator. When comparing the existing protocol with the proposed MIPSOE protocol it is inferred that there is an improvement in terms of network lifetime, throughput, delay, and packet delivery ratio.