Efficient Analytical Approach Research Articles

Analytical approach for seismic analysis of onshore wind turbines considering soil-structure interaction

The aim of this study is to present an efficient analytical approach, based on a combination of transfer matrix formulations and modal superposition, to perform seismic response analysis of onshore wind turbines (WT) incorporating the effects of soil-structure interaction (SSI). The WT tower and rotor-nacelle assembly (RNA) are idealised as a segmented Timoshenko beam-column and lumped mass, respectively. SSI is taken into account using elastic springs at the bottom of the tower to model soil flexibility. The mass of the foundation is also considered in the mathematical model as a lumped mass at the base of the tower. As the serviceability limit state tends to be the governing design condition for WTs, the soil behaviour is idealised as linear-elastic with equivalent linear stiffness. Firstly, natural frequencies and mode shapes of the WT are obtained using the transfer matrix method (TMM), which is based on analytically-calculated state vectors of beam-column members, and state vectors of joints at the top and bottom of the tower. The entire vibrating structure is simplified into an equivalent single-degree-of-freedom (SDOF) system using mode shapes calculated from TMM. The seismic responses are derived using the Newmark-Beta method and modal superposition. The application of TMM for free vibration analysis is validated with reference to results from existing literature. Additionally, the accuracy of the method for calculation of seismic responses is verified using finite-element software. Three different ground models are considered, namely stratum over half-space, stratum over rigid base, and elastic half-space; and the effect of each on the free vibration and seismic responses are examined in terms of displacement and base shear time-histories of the WT with varying foundation geometries. The effects of varying soil properties on the natural frequencies and seismic responses of the WT are also investigated. Finally, the dynamic responses of the model subjected to different seismic time-histories are presented comparatively, to highlight the significant effects of the frequency content of ground motion records.

Exact soliton solutions to the time-fractional Kudryashov model via an efficient analytical approach

Exact soliton solutions to the time-fractional Kudryashov model via an efficient analytical approach

Error Probability of a Coherent M-ary PSK FSO System Influenced by Phase Noise

In this paper, we aim to develop an analytical framework for design and analysis of new generation mobile networks fronthaul/backhaul links based on the application of free-space optical (FSO) technology. Taking the receiver hardware imperfections into account, we present an efficient analytical approach in analyzing average symbol error probability (SEP) of the coherent FSO system employing M-ary phase-shift keying (PSK). Optical signal transmission is influenced by pointing errors and atmospheric turbulence. The signal intensity fluctuations caused by atmospheric turbulence are modeled by general Málaga (M) distribution, which takes into account the effect of multiple scattered components. We estimate the range of the signal-to-noise ratio at which the SEP floor appears, as well as the value of this non-removable error floor. The results illustrate that the effect of imperfect phase error compensation on the SEP is more critical under weaker turbulence conditions and for higher order modulation formats. Based on the analytical tools presented here, it is possible to estimate tolerable value of standard deviation of phase noise for the given value of SEP. This value of standard deviation is an important parameter in designing the phase-locked loop filter in the receiver.

Design and Fabrication of a Gas Sensor Based on a Polypyrrole/Silver Nanoparticle Film for the Detection of Ammonia in Exhaled Breath of COVID-19 Patients Suffering from Acute Kidney Injury.

One of the serious complications of COVID-19 is acute kidney injury (AKI), leading to a decrease in kidney function and even death. The concentration of ammonia (NH3) in the exhaled breath (EB) of COVID-19 patients suffering from AKI symptoms will be significantly increased. In this work, the detection of breath NH3 was performed at gold interdigital electrodes modified with a soluble polypyrrole microparticle and silver nanoparticle film (Au-IDEs/S-PPyMPs/AgNPs) as a noninvasive chemiresistor gas sensor. The response behavior of unmodified and modified gas sensors toward NH3 and other interfering compounds was studied. The Au-IDEs/S-PPyMPs/AgNPs exhibited NH3 detection in the linear dynamic range of 1.00-19.23 ppm, with a limit of detection of 0.12 ppm. Finally, the fabricated gas sensor was used to monitor the NH3 concentration in the EB of COVID-19 patients suffering from AKI symptoms. For this purpose, the gas sensor was validated in 19 EB samples (seven COVID-19-positive patients, four COVID-19-negative patients, and eight post-COVID-19 patients). The gas sensor was directly exposed to the EB samples, followed by recording the changes in electrical resistance via a low-cost digital multimeter. The sensing mechanism was explained as the interaction between breath NH3 and sensing materials. The breath NH3 concentrations have a desirable correlation (R2 = 0.8463) with the estimated glomerular filtration rate (eGFR) values in COVID-19-positive patients. The fabricated gas sensor can distinguish COVID-19-positive patients suffering from AKI symptoms from COVID-19-negative patients and post-COVID-19 patients. The present work can pave the way for the development of a simple and efficient analytical approach for COVID-19 patients with AKI without the need for sample pretreatment.

Research on spatiotemporal variation characteristics of soundscapes in a newly established suburban forest park

Passive acoustic monitoring has developed rapidly as a tool for ecological assessments, and the use of acoustic indices to assess biodiversity in urban forests promises to be a low-cost and efficient analytical approach. However, the accuracy of using acoustic indices to characterize biodiversity may be compromised by excessive human interference. The acoustic complexity index (ACI) and normalized difference soundscape index (NDSI) were chosen to determine their application value, and explore the spatiotemporal patterns of change in the soundscape of a newly established suburban forest park in China. To understand the influence of drivers such as different sound source types, road distance, and vegetation structure on the soundscape, the Eastern Suburb Forest Park was selected as the study area, and 55 recording points (200 m intervals, 5 × 11 grids) were set up using a systematic grid. Passive acoustic monitoring was performed for four consecutive days in each season, and the spatiotemporal variation of the soundscape was visualized based on indices interpolation. The results showed that when using ACI and NDSI to rapidly assess biodiversity in urban forest environments, attention needs to be paid to the implications of seasonal fluctuations on indices. The temporal variation of the soundscape was closely related to the natural rhythms and vocal activity intensity of organisms. Distance to a nearby main road, distance to water, and structural complexity of vegetation were key factors influencing spatial variation. The findings support the use of acoustic methods to assess the characteristics of soundscapes in human-built urban forests. Soundscape mapping visualizes hotspots and moments of ecoacoustic activity, and has great potential for development in the conservation and management of suburban forest soundscapes.

An efficient analytical approach to assess root cause of nonlinear electric vehicle gear whine

Noise, vibration, and harshness (NVH) issues pose considerable challenges for electric vehicle powertrain engineers. Gear vibrations generate an intrusive gear whine noise, with significant impact on the sound quality of electric powertrains. Dynamic transmission error (DTE) is the most quantitative indicator for gear NVH. Backlash, time variable meshing stiffness and damping contribute to DTE. Hence, a better understanding of these excitation sources is essential. A gear tribodynamics model is developed using potential energy method to estimate time variable meshing stiffness (TVMS). A fully analytical time-efficient model is proposed for lubricated contact stiffness based on transitions in the regimes of lubrication. The model accounts for the combined effects of surface elasticity and lubricant stiffness. Film thickness and damping coefficients are transiently updated at each instant during meshing cycle. The predictions from this model are compared with measured results from the literature and predicted results from Hertz contact model. The lubricated contact model successfully shows the contribution of the lubricant stiffness to TVMS and its variations with elasticity and viscosity parameters during meshing cycle. Gear harmonic and super-harmonic resonances are accurately estimated in terms of amplitude, frequencies and stiffness softening nonlinearities. Time history responses and phase-displacement diagrams show good agreement with the gear dynamics response at the main harmonic and second super-harmonic frequencies. The proposed model has a reasonable accuracy, significantly better than those from Hertzian contact models, and is considerably time efficient in comparison to numerical EHL solvers.

Analysis of transition regions of bi-linear, parametrically driven, two-oscillator model: Resonant excitation in the neighborhood of non-similar NNMs

Present study is concerned with the analysis of special family of parametric instability tongues emerging in the dissipative bi-linear model of two oscillators subjected to parametric excitation. The study focuses on analytical approximation and characterization of instability regions corresponding to the resonant, non-similar NNMs. In spite of the complexity of the problem under investigation, we succeeded in devising a novel and efficient analytical approach, which provides an explicit analytical approximation of transition regions corresponding to the special family of most significant sub-harmonic (m:1) resonance tongues, corresponding to IP and OP NNMs. Analytical study of the model reveals some interesting and unusual properties of instability regions of damped-driven, bi-linear system. Presently devised analytical procedure shows a fairly good correspondence with the direct numerical simulations of the full model.

Finite-time H∞ control of linear singular fractional differential equations with time-varying delay

Abstract In this paper, we propose an efficient analytical approach based on fractional calculus and singularity value theory to designing the finite-time $H_\infty $ controller for linear singular fractional differential equations with time-varying delay. By introducing new fractional-order $H_\infty $ norm, the state feedback controller is designed to guarantee that the closed-loop system is singular, impulse-free and finite-time stable with prescribed $H_\infty $ performance. New sufficient conditions for designing the $H_\infty $ finite-time controller are presented. The results of this paper improve the corresponding ones of integer-order singular systems with time-varying delay. Finally, a numerical example demonstrates the validity and effectiveness of the proposed theoretical results.

Simultaneous determination of benthiavalicarb-isopropyl and its four metabolites in fruits and vegetables using ultrahigh -performance liquid chromatography/tandem mass spectrometry

ABSTRACT We established an efficient analytical approach for simultaneous determination of benthiavalicarb-isopropyl and its four metabolites (KIF-230-M1, KIF-230-M3, KIF-230-M4, and KIF-230-M5) in fruits and vegetables. Samples were extracted with acidified acetonitrile, with octadecylsilane and graphitised carbon black as sorbent for clean-up, and UHPLC-MS/MS for determination. The approach was determined at spikes of 5, 50, and 500 μg kg−1. The recoveries of the six matrices analyzed ranged from 74.5% to 115.6% with 0.5–12.6% for intra-day RSDr (n = 5), and 0.4–13.8% for inter-day RSDR (n = 15). The five analytes in all matrices achieved high linearity (R2 > 0.9917). The limit of quantification (LOQ) of benthiavalicarb-isopropyl as well as its four metabolites in all matrices was 5 μg kg−1. This analytical approach allows for monitoring residues of benthiavalicarb-isopropyl and its metabolites in vegetables and fruits.

Probabilistic Gas Leak Rate Estimation Using Submodular Function Maximization With Routing Constraints

Harmful greenhouse gases such as methane are prone to leak during extraction, transportation, and storage in oil fields. Therefore we must monitor gas leak rates to keep such fugitive emissions in check. However, most currently available approaches incur significant computational costs to generate informative paths for mobile sensors and estimate leak rates from the collected data. As such, they do not scale to large oil fields and are infeasible for real-time applications. We address these problems by deriving an efficient analytical approach to compute the leak rate distribution and Expected Entropy Reduction (EER) metric used for path generation. Moreover, a faster variant of a submodular function maximization algorithm is introduced, along with a generalization of the algorithm to find informative data collection walks with arc routing constraints. Our simulation experiments demonstrate the approach’s validity and substantial computational gains.

Analytical approach for the fast estimation of time-dependent wellbore stability during drilling in methane hydrate-bearing sediment

Methane hydrates (MHs) have been widely considered to be clean energy resources that are stored in great quantities in the ocean. During wellbore drilling in methane hydrate-bearing sediment (MHBS), the coupling effect of the mass/heat transfer, MH dissociation and creep response of MHBS makes wellbore stability a complex time-dependent problem.Aimed at efficiently estimating the time-dependent wellbore stability when drilling in MHBS, this study provides an efficient analytical approach (solution) for quickly predicting the plastic zone and displacement around the wellbore, precisely considering the rheological properties (i.e.., viscoelastic-brittle-plastic) of the sediments, the effect of the unsteady seepage/temperature fields and the sharp deterioration of the mechanical properties of the sediments after hydrate dissociation. Because of the time-dependent hydrate dissociation caused by the unsteady seepage/temperature field, a multiregion problem with time-varying boundaries is deduced, and the Laplace transformation is employed when solving the differential equations under various working conditions. The analytical solutions agree well with the results from the numerical method under the same assumptions, and the boundary and compatibility conditions of the analytical solutions are satisfactorily verified. Furthermore, the analytical predictions of the dissociation front radius and the distribution of the pressure and effective stress near the wellbore are essentially consistent with the results from complex numerical simulations, which validates the applicability of the analytical solutions. A parametric investigation on the specific effect of the rheological properties and drilling fluid pressure on the wellbore stability during drilling in MHBS is finally performed. The results show that both the plastic radius and displacement increase sharply at the beginning of drilling. When the plastic zone is smaller than the dissociated region, the slower the creep rate of MHBS is, the slower the plastic zone expansion in the dissociated region is, and the slower the displacement increase is over time.

Complex Variable Solution for Stress and Displacement of Layered Soil with Finite Thickness

The static problem of a layered isotropic elastic body is a very useful research subject in relation to the analysis and design of foundation works. Due to the complexity of the problem, there is no analytical solution to the problem so far. This study provides an efficient analytical approach to accurately calculate the displacement and stress fields of the soil. The constraints of bedrock on soil, different soil layer thickness and the shear stress of the foundation on soil were all taken into account in the analysis. In this study, each layer is regarded as an isotropic elastomer with infinite width, and the layers are in complete contact. By using conformal mapping, each layer is mapped to a unit circle, and the two complex potential functions are expanded into Taylor series with unknown coefficients. These unknown coefficients are obtained by satisfying boundary conditions and continuity conditions. The boundary and continuity conditions were verified in this paper. As a validation step, we compared the analytical results for the settlement with the results of the ANSYS numerical simulations and found good agreement. Parametric analyses were also carried out to investigate the influence of different distribution forms of base pressure on surface settlement, and the effects of layered properties on the surface settlement and stress field.

2-Tuple Linguistic Model-based Circular Maturity Assessment Methodology: A Case for Agriculture

There is a rising perception among businesses, society, and institutions that the future of production systems hinges on shifting to a circular economy (CE). The CE approach unlocks new potentials for design and better manufacturing methods. This paper intends to create a Circular Maturity Model guiding organizations to gain a comprehensive understanding of their circularity level and have a powerful insight into their future strategies. A functional methodology is generated with a multi-criterion (MCDM) and group decision-making approach. This methodology intends to evaluate the organization's maturity with five main dimensions and fifteen critical factors. The 2-Tuple Linguistic (2-TL) model is suggested to evaluate the circularity factors to create a more efficient analytical approach to reach the maturity score. The 2-TL model is selected to emphasize the results' interpretability and create a decision-making process closer to human thinking. Plus, an MCDM technique, MARCOS, is suggested for strategy selection to improve maturity. The suggested assessment methodology is applied to an agriculture company in Turkey. Thanks to its critical importance for emerging economies like Turkey, the agriculture sector is selected.

Molecular Mapping of Sebaceous Squalene by Ambient Mass Spectrometry.

Squalene (SQ), a highly unsaturated sebaceous lipid, plays an important role in protecting human skin. To better understand the role of SQ in clinical medicine, an efficient analytical approach is needed to comprehensively study the distribution of SQ on different parts of the skin. In this study, sebaceous lipids were collected from different epidermal areas of a volunteer with sampling probes. Thermal desorption-electrospray ionization/mass spectrometry (TD-ESI/MS) was then used to characterize the lipid species on the probes, and each TD-ESI/MS analysis was completed within a few seconds without any sample pretreatment. The molecular mapping of epidermal squalene on whole-body skin was rendered by scaling the peak area of the extracted ion current (EIC) of SQ based on a temperature color gradient, where colors were assigned to the 1357 sampling locations on a 3D map of the volunteer. The image showed a higher SQ distribution on the face than any other area of the body, indicating the role of SQ in protecting facial skin. The results were in agreement with previous studies using SQ as a marker to explore sebaceous activity. The novelty and significance of this work are concluded as two points: (1) direct and rapid detection of all major classes of sebaceous lipids, including the unsaturated hydrocarbons (SQ) and nonpolar lipids (e.g., cholesterol). The results are unique compared to other conventional and ambient ionization mass spectrometry methods and (2) this is the first study to analyze SQ distribution on the whole-body skin by a high-throughput approach.

Efficient analytical approach for stability analysis of infrastructure slopes

Transportation infrastructure is of vital importance to economic prosperity. Transportation infrastructure (e.g. railway, highway) is usually supported by a large number of cuttings and embankments, which require regular maintenance to ensure serviceability and safety. The funding available for maintenance is usually limited. Hence, the key challenge is to identify the infrastructure slopes that require the most urgent attention. This paper presents an analytical framework that can be efficiently used for slope stability analysis at network scales. The analytical approach enables calculation of the factor of safety according to the traditional approach, the over-design factor following Eurocode 7 and the probability of failure considering uncertainty of parameters. Application of the analytical framework is illustrated with examples. The analytical approach can readily be incorporated into a spreadsheet program as user-defined functions, which are particularly useful for the generic slope stability analysis of long linear transportation infrastructure.

Design of an Efficient Fabry-Perot Biosensor Using High-Contrast Slanted Grating Couplers on a Dual-Core Single-Mode Optical Fiber Tip

A novel and efficient Fabry-Perot biosensor on the tip of a dual-core single-mode optical fiber is proposed. The incident light emerges from one of the cores and is coupled to the second core via high-contrast silicon nitride slanted grating couplers (SGCs), separated by a silicon nitride waveguide segment disposed along the fiber tip. The challenges in designing high-contrast SGCs of very short length were overcome using an efficient analytical design approach augmented by simulations in 2D, resulting in grating designs that produce core-to-core coupling efficiencies of up to 29%. The waveguide segment separating the SGCs acts as a Fabry-Perot sensing cavity producing narrow Fabry-Perot fringes in the transmittance spectrum of the structure. Monitoring these fringes leads to bulk sensitivity and figure of merit of 50 - 100 nm/RIU and 16.67 - 33.34 (RIU $^{-1}$ ), for sensing a large range of biomaterials. The structure operates in transmission, thus eliminating the need to separate the reflected light from the incident light at the input of the fiber, which simplifies the interrogation system. Properly packaged, the fiber tip can be dipped or inserted directly into the sensing medium, which removes the need for microfluidics. The scheme enables robust, flexible, compact, and remotely-interrogated biosensors.

A novel framework for hosting capacity analysis with spatio-temporal probabilistic voltage sensitivity analysis

Smart grids are envisioned to accommodate high penetration of distributed photovoltaic (PV) generation, which may cause adverse grid impacts in terms of voltage violations. Therefore, PV Hosting capacity is being used as a planning tool to determine the maximum PV installation capacity that causes the first voltage violation and above which would require infrastructure upgrades. Traditional methods of Hosting capacity analysis are scenario based and computationally complex as they rely on iterative load flow algorithms that require investigating a large number of scenarios for accurate assessment of PV impacts. Therefore, this paper presents a computationally efficient analytical approach to compute the probability distribution of voltage change due to random behavior of randomly located multiple distributed PVs. The proposed approach is based on Spatio-temporal probabilistic voltage sensitivity analysis that exploits both spatial and temporal uncertainties associated with PV injections. Thereafter, the derived distribution is used to quantify voltage violations for various PV penetration levels and subsequently determine the hosting capacity of the system without the need to examine large number of scenarios. Results of the proposed framework are validated via conventional load flow based simulation approach on the IEEE 37 and IEEE 123 node test systems.

A new analytical approach for preconcentration, separation and determination of Pb(II) and Cd(II) in real samples using a new adsorbent: Synthesis, characterization and application

A green and efficient analytical approach was reported for simultaneous preconcentration, and separation of Pb(II) and Cd(II) in water, vegetables, and barbecue samples by dispersive solid-phase microextraction prior to their determination using flame atomic absorption spectrometry. A new poly-3-hydroxy butyrate-polyvinyl triethyl ammonium chloride comb-type amphiphilic cationic block copolymer (PHBvbNCl) was synthesized and characterized. Main variables such as pH, sorbent amount, adsorption time, eluent type, desorption time, and sample volume were optimized. Detection limits and working ranges for Pb(II) and Cd(II) were 0.03 μg L-1, 0.15 μg L-1, 0.1–250 μg L-1 and 0.5–375 μg L-1, respectively. Enhancement factor for Pb (II) and Cd (II) were 114 and 98. The adsorption capacity of PHBvbNCl for Pb(II) and Cd(II) was 175.2 mg g−1 and 152.9 mg g−1. After the accuracy of the method was confirmed by the analysis of certified reference materials, it was successfully applied to real samples. Finally, the analytical performance of the present method was compared with other methods.

Numerical and analytical studies of ship deckhouse impact with steel and RC bridge girders

Bridges crossing navigable waterways are under the threat of accidental collisions from passing ships. However, previous research focus was mainly placed on ship collision with bridge substructures while ship-bridge superstructure collisions were largely ignored. In fact, superstructure collision accidents between bridge girders and ship deckhouses have occurred with increasing frequency in the past decade. Therefore, it is important to evaluate the bridge girder capacity against ship superstructure collisions in the design phase. In this paper, finite element models of a ship deckhouse and three types of bridge girders are established. Numerical simulations are conducted to investigate the response of the bridge girders under ship deckhouse collisions. The application and validity of the commonly adopted rigid body assumption of bridge girders are investigated. The results are compared with integrated collision simulations where both the striking deckhouse and the struck bridge girder are modelled as deformable bodies. The impact force, structural failure mode, and energy dissipation during the collision process are discussed. The effects of girder material and structural configuration are also discussed. Based on the numerically obtained failure mode of the ship deckhouse, an efficient analytical design approach for bridge girders against ship deckhouse impacts is proposed.

On Convergence Analysis and Analytical Solutions of the Conformable Fractional Fitzhugh–Nagumo Model Using the Conformable Sumudu Decomposition Method

The current article studied a nonlinear transmission of the nerve impulse model, the Fitzhugh–Nagumo (FN) model, in the conformable fractional form with an efficient analytical approach based on a combination of conformable Sumudu transform and the Adomian decomposition method. Convergence analysis and error analysis were also carried out based on the Banach fixed point theory. We also provided some examples to support our results. The results obtained revealed that the presented approach is very fantastic, effective, reliable, and is an easy method to handle specific problems in various fields of applied sciences and engineering. The Mathematica software carried out all the computations and graphics in this paper.