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Defining the required trackability level of the target condition for the testing facility reconditioning unit represents an unresolved challenge in improving the reproducibility of load-based tests and corresponding performance rating standards development. To enhance the reproducibility of such testing methodology, this paper presents and discusses a new feed-forward compensation technique based on the development of a transfer function model for the delay and offset characteristics of the psychrometric room's air temperature and humidity modulations with reference to the target signal from the room emulator. It is demonstrated that the proposed methodology enables offset and delay reduction in the trackability of the return air condition within 60 s at different testing conditions, enhances the reproducibility of the test results to limit performance deviations to within 2 %, and achieves closely matched controlled parameter modulations during load-based tests. [ABSTRACT FROM AUTHOR]

• To introduce BCOHHS for wrapper-based feature selection • A binary using the X-shaped function of the hybrid, HHO, with chaotic opposition-based initialization and simulated annealing • Evaluated the performance of the BCOHHS using high-dimensional medical data sets Harris Hawks Optimization (HHO) is a relatively new meta-heuristic algorithm that has shown promise in solving various optimization problems. However, HHO suffers from some limitations that can affect its performance. The two main drawbacks of HHO are population diversity and local optima. To overcome these limitations and adapt it to solve feature selection issues, a new meta-heuristic, Chaotic Opposition Harris Hawks Optimization with Simulated Annealing (COHHS), is proposed in this paper. Two main improvements are proposed for the HHO. The first one, the chaotic opposition, is applied at the initialization phase of HHO to improve the population diversity of the search agents. The second one, simulated annealing, is applied to find the optimal solution during each iteration to improve HHO exploitation. The proposed method is a dynamic structure that was originally designed to solve problems with continuous optimization. In this paper, we propose a binary COHHS (BCOHHS) using X-shaped functions to boost the efficiency of feature selection. The KNN classifier is used to evaluate the classification accuracy. The performance of the proposed method is evaluated on nine high-dimensional medical datasets and compared with other optimization methods. The experimental results confirm the superiority of the BCOHHS method over the other methods on the majority of the datasets. [ABSTRACT FROM AUTHOR]

This paper presents a binary variant of a novel physics-based meta -heuristic optimization algorithm, namely Light spectrum optimizer (LSO), for tackling both the 0–1 knapsack (KP01) and multidimensional knapsack problems (MKP). Because of the continuous nature of the standard LSO that contradicts the knapsack problem's discrete nature, two various transfer functions: S-shaped and X-shaped, are used to convert the continuous values produced by LSO into discrete ones. Some binary solutions produced by the binary LSO (BLSO) may be infeasible, so an improvement-repair strategy is used to convert those solutions into feasible ones by making some improvements on them. Moreover, the classical LSO was modified in this study to propose a new binary variant, namely BMLSO, with better exploration and exploitation operators for overcoming the knapsack problems. Additionally, a novel method, which simulates the swarm intelligence behaviors and the simulated binary crossover (SBX) to accelerate the convergence speed with avoiding stuck into local minima, has been proposed for producing a new binary variant of MLSO known as BHLSO. To verify the performance of the proposed binary variants of LSO, 45 benchmark instances of KP01 and 30 benchmark instances of MKP used commonly in the literature have been used in our experiments. The experimental findings show the superiority of BHLSO for both KP01 and MKP compared with several well-known algorithms in terms of CPU time, convergence speed, and accuracy. [ABSTRACT FROM AUTHOR]

• Biodiversity of Chrysophyceans stomatocysts is high in low-latitude and high-altitude mountain lakes. • Altitude, a proxy of temperature change, is the most important predictor of chrysophycean. stomatocyst assemblages. • Chrysophycean cysts have a great potential as a powerful tool for temperature reconstructions in alpine regions of the Hengduan Mountains. The Three Parallel Rivers of Yunnan Protected Area (TPRYPA) is in the core area of the Hengduan Mountains, characterized by paralleling alternately high mountains and canyons that led to significant vertical temperature variation. Developing a climate transfer function for this region is crucial for both biodiversity protection and enhancing our understanding of feedback mechanisms between low-latitude and high-altitude areas in the context of global climate change. We investigated the chrysophycean stomatocyst assemblages from surface sediments of 46 high mountain lakes (altitude: 3244 to 5043 m) in the TPRYPA to assess the suitability of cysts in prediction of climate variability in high mountains. A total of 194 morphotypes were identified. Gradient forest (GF) model identified that altitude is the key environmental gradient with relation to cyst assemblages and cyst assemblages changed the composition substantially at altitude of 3200 and 4400 m, respectively. Cyst-based inference model for altitude using weighted-averaging method resulted in cross-validated jack-knifed-R2 of 0.60. The cyst-altitude transfer functions suggest that chrysophycean stomatocysts have a great potential as a powerful tool for climate reconstructions in alpine regions of the Hengduan Mountains. [ABSTRACT FROM AUTHOR]

Transfer functions of asymmetric flames subjected to incident flow perturbations are explored using the classical kinematic model, the G-equation, parameterized by flame tip angle α , flame-base incline angle β , and eccentricity e. With perturbations of various frequencies, we analyze perturbed asymmetric flames and derive analytical formulations of Flame Transfer Functions (FTF) for various flame conditions. It is observed that the gain of the asymmetric conical flame is increased compared to the symmetric case. Meanwhile, the amplification effect of the V-shaped flame is considerably suppressed as the flame becomes asymmetric. That means with a proper asymmetric geometry setting, the V-shaped flame no longer tends to amplify the perturbation and in other words becomes less susceptible to combustion instability. These findings have significant value for the future design and optimization of propulsion systems, where improving flame stability and reducing thermoacoustic instabilities are critical. Subsequently, a numerical study is conducted to verify the FTF results and examine the response of asymmetric flames under various perturbation levels. It has been demonstrated that the asymmetric conical flame is minimally affected by the amplitude of these perturbations, and the asymmetric V-shaped flame is highly sensitive to the convective amplitudes. • Analytically derive flame transfer function of asymmetric conical and V-shape flame. • Consider different velocity perturbation models and flame geometric parameter. • Discover the gain attenuation phenomenon for V-shape flame with asymmetric configuration. • Numerically study the nonlinearity of flame transfer functions of asymmetric flame. [ABSTRACT FROM AUTHOR]

In recent years, the escalation of anthropogenic noise within marine environments has become a pressing ecological concern. Despite the proliferation of guidelines aimed at mitigating this issue, their adoption remains non-compulsory. The International Maritime Organization (IMO) advocates for noise reduction through the refinement of propeller design and heightened research to curtail acoustic emissions, ensuring that such measures do not compromise propulsive efficiency. This review delves into the array of strategies devised to attenuate noise pollution. It scrutinizes the methodologies employed to evaluate the hydroacoustic attributes of propellers, including experimental and computational approaches. Furthermore, it summarizes the techniques employed in the multiobjective optimization of propellers, which involves balancing the maximization of efficiency against the minimization of noise emission. The findings highlight the necessity for a comprehensive, interdisciplinary approach to the hydroacoustic optimization of marine propellers, encompassing cavitation experiments and advanced numerical simulations. In the field of propeller optimization, the traditional reliance on genetic algorithms is giving way to the adoption of neural networks and surrogate models derived from computational fluid dynamics data, particularly when addressing complex, nonlinear phenomena such as hydro-acoustics and cavitation. • Hydro-acoustic optimization of propellers needs a multi-disciplinary approach. • There is a growing awareness about the threat of URN for marine life. • Background noise and the arrangement of equipment are crucial for URN tests. • Quadrupole non-linear noise term should be considered for hydro- acoustics. • Artificial Neural Networks can help to build reduced order models for optimization. [ABSTRACT FROM AUTHOR]

• New research framework to characterize time lag pattern of GWLs to Precipitation. • Based on variation point to describe the evolution of GWL before and after the SWDP. • The GWL in the toe of alluvial fans exhibit stronger declines due to over-extraction. • The toe of alluvial fans in the eastern plain exhibits longer lag times than western. • Groundwater extraction being the dominant factor affecting GWL fluctuations. The fluctuations in groundwater levels (GWLs) in the Beijing Plain area are profoundly affected by precipitation (Pre) and groundwater (GW) overexploitation, altering regional water cycle processes and constraining regional economic and ecological development. The South-to-North Water Diversion Project (SWDP) has altered water supply structure in Beijing, leading to a new pattern in GWL fluctuations. This study quantitatively analyzes the evolution patterns of shallow GWLs and quantifies the response relationship between Pre-driven GWL-response on spatial and temporal scales before and after the SWDP. Using GWL and Pre data from 2000 to 2021, employs the coefficient of variation to analyze interannual variability, identifies variation points using the Pettitt and sliding T-test combined with correlation coefficient-based method for the classification of jump degree (R_Jump degree), subsequently divides the sub-sequences. The hydrological trend variation classification method based on correlation coefficient (R_Trend) is used to quantify the spatiotemporal evolution patterns of GWLs in each sub-sequence, and cross-correlation analysis is utilized to examine the time-lag characteristics of GWL responses to Pre in each sub-sequence. The results indicate: (1) GWLs exhibited jump variations in 2015 and 2017, with variation degrees mainly of moderate and strong, and correlation coefficients ranging from 0.18 to 0.67; (2) The overall trend of GWLs shifted from a significant decline to a substantial rebound before and after the SWDP. However, GWLs in the toe of the alluvial fan continued to show a decreasing trend until 2017; (3) The time lag between Pre and GWLs shortened by 6–10 months before and after the SWDP, with the toe of the alluvial fan showing a longer lag time due to over-exploitation. The Pre-GWL lag pattern mainly depends on GW extraction. Compared to existing methods, this paper proposes a research framework for systematically and comprehensively quantifying the evolution of GWLs and their response patterns to Pre, clearly revealing the natural-artificial water cycle processes in the Beijing Plain, providing scientific basis for ecological conservation and water resource management. [ABSTRACT FROM AUTHOR]

Conventional grid-code specifications for dynamic ancillary services provision such as fast frequency and voltage regulation are typically defined by means of piece-wise linear step-response capability curves in the time domain. However, although the specification of such time-domain curves is straightforward, their practical implementation in a converter-based generation system is not immediate, and no customary methods have been developed yet. In this paper, we thus propose a systematic approach for the practical implementation of piece-wise linear time-domain curves to provide dynamic ancillary services by converter-based generation systems, while ensuring grid-code and device-level requirements to be reliably satisfied. Namely, we translate the piece-wise linear time-domain curves for active and reactive power provision in response to a frequency and voltage step change into a desired rational parametric transfer function in the frequency domain, which defines a dynamic response behavior to be realized by the converter. The obtained transfer function can be easily implemented e.g. via a proportional-integral (PI)-based matching control in the power loop of standard converter control architectures. We demonstrate the performance of our method in numerical grid-code compliance tests, and reveal its superiority over classical droop and virtual inertia schemes which may not satisfy the grid codes due to their structural limitations. • Implementing piece-wise linear grid-code curves in converters lacks standard methods. • Our approach implements piece-wise linear grid-code curves for converter systems. • We convert time-domain grid-code curves to frequency-domain transfer functions. • The transfer functions can be implemented in standard converter control setups. [ABSTRACT FROM AUTHOR]

New investigations performed with a multi-proxy approach provide a robust climate reconstruction for the Late-Glacial in the Massif Central, France. The temperature reconstruction from Coleoptera is obtained from the Mutual Climatic Range Method, or "MCR" method, based on the range of climates corresponding to the area occupied today by the species identified in fossil assemblages. The Weighthed Averaging Partial Least Squared (WA-PLS) method is used to produce mean July temperature estimates from Chironomid assemblages. Climate reconstruction from pollen data is performed using an assemblage approach, the Modern Analogue Technique. During the Late-Glacial the July temperature (Tmax) reconstructed from beetles (Coleoptera) was lower than the current Tmax of 18.9 °C. Summer conditions were close to the present at the beginning of the Oldest Dryas (17400–14600 cal. BP), and during most of the Allerød (13900–12800 cal. BP). During the Younger Dryas (12800–11700 cal. BP) Tmax estimates ranged from 12 to 13 °C, much lower than today. The Tmax increased at the onset of the Holocene (11700 cal. BP), reaching values close to the modern conditions from the beginning of the period. Tmax reconstructed from chironomids shows an initial warming around 15000 cal. BP, with a Tmax rise from 7 °C to 11 °C. A maximum (13.5 °C) was reached around 13800 cal. BP. A second optimum of 16 °C occurred after 10800 cal. BP. The Late-Glacial Interstadial (LGI) is marked by temperature decreases (from 13 to 12 to 10–9 °C) around 13200–12900 cal. BP. A second climate minimum was reached around 12600 cal. BP, during the Younger Dryas (Tmax about 10 °C). The end of the Younger Dryas seems to have been warmer, with a Tmax of about 13 °C, just before the early Holocene climate improvement. Pollen-inferred results showed that the Late-Glacial climate at Roustières was characterized by colder and drier winter and summer seasons than today, and by conditions close to the modern ones around 11700 cal. BP, at the onset of the Holocene. Climate conditions comparable to the modern ones were also evidenced at the end of the Allerød, with colder than today conditions evidenced from both Tmax and Tmin (January temperature). During the Oldest and Younger Dryas the coldest month showed a temperature of −13 °C, while summers appeared more moderate (warmest month around 16 °C). Cold conditions were also reconstructed during the Bølling, while temperatures comparable to present-day values were reached during the Allerød. A cold oscillation occurred around 13400 cal. BP. Particularly dry conditions were reconstructed during the Oldest Dryas (17000–15800 cal. BP). From 15800 to the end of the Younger Dryas, the precipitation oscillated around 750 mm, but increased during the Allerød and the Holocene periods. These climatic trends reconstructed by the three proxies allowed identifying the temperate periods (LGI and the Holocene) and the cold events (Younger Dryas) of the Late-Glacial period. However, difficulties due to different sampling resolutions emerged, and several discrepancies linked to the proxy or the methods used are discussed. [ABSTRACT FROM AUTHOR]

This paper illustrates the investigation of higher-scale interconnected wind turbine to realize its analytical design and simulation performance in terms of reduced order model. The present research is aimed to visualize the efficacy of the propounded harris hawks optimization (HHO) approach for different reduced order transfer functions with reference to model order reduction studies. Compared to the higher-scale model, the applied methodology aims to obtain better results in terms of steadiness and computational effort. Moreover, to realize a higher-dimensional power system, the implementation of the HHO may proffer more effectiveness and robustness as opposed to the state-of-the-art optimization techniques. The applied methodology aims to obtain better results in terms of stability and computational effort. Furthermore, to realize a higher dimensional system, implementation of the HHO may offer more effectiveness and robustness as opposed to the state-of-the-art optimization techniques. • Novel HHO integrated MOR for interconnected wind turbines have been devised. • Optimization approach using HHO has been realized. • Comparative analysis in terms of various control domains has been structured. [ABSTRACT FROM AUTHOR]

The second-order cone linear complementarity problem (SOCLCP) is a generalization of the classical linear complementarity problem. It has been known that SOCLCP, with the globally uniquely solvable property, is essentially equivalent to a zero-finding problem in which the associated function bears much similarity to the transfer function in model reduction [38]. In this paper, we propose a new rational Krylov subspace method to solve the zero-finding problem for the symmetric and positive definite SOCLCP. The algorithm consists of two stages: first, it relies on an extended Krylov subspace to obtain an approximation of the zero root, and then applies multiple-pole rational Krylov subspace projections iteratively to acquire an accurate solution. Numerical evaluations on various types of SOCLCP examples demonstrate its efficiency and robustness. [ABSTRACT FROM AUTHOR]

We theoretically describe and numerically investigate the operation of "vectorial" optical differentiation of a three-dimensional light beam, which consists in simultaneous computation of two partial derivatives of the incident beam profile with respect to two spatial coordinates in different transverse electric field components. It is implemented upon reflection of the beam from a layered structure by simultaneously utilizing the effect of optical resonance and the spin Hall effect of light. As an example of a layered structure performing this operation, we propose a three-layer metal–dielectric–metal (MDM) structure. We show that by choosing the parameters of the MDM structure, it is possible to achieve the so-called isotropic vectorial differentiation, for which the intensity of the reflected optical beam (squared electric field magnitude) is proportional to the squared absolute value of the gradient of the incident linearly polarized beam. The presented numerical simulation results demonstrate high-quality vectorial differentiation and confirm the developed theoretical description. • We investigate the operation of "vectorial" optical differentiation. • It consists in computing two different spatial derivatives in two field components. • Isotropic vectorial differentiation leading to gradient computation is considered. • We design metal–dielectric–metal multilayer implementing isotropic differentiation. • The obtained results are promising for analog optical computing and edge detection. [ABSTRACT FROM AUTHOR]

Bone conduction microphones (BCM) offer an interesting solution for speech recording in noisy environments. They provide enhanced ergonomics and reduced sensitivity to ambient noise compared to conventional aerial microphones. However, BCM exhibit inherent limitations in intelligibility and sound quality, even in quiet conditions, restricting their widespread adoption. To address these limitations, filtering techniques employing transfer functions between a conventional Air Conduction Microphones (ACM) and BCM have been explored. However, this study demonstrates the inadequacy of this approach due to the non-constant nature of the transfer function. An experiment involving ten subjects revealed that the transfer function between an ACM and a BCM, derived with a direct oral excitation, varies with a mouth opening. Additionally, a numerical investigation using finite element methods confirmed that the mouth opening significantly impacts the transfer function between the oral cavity sound pressure and an air conduction microphone but has negligible effect on the transfer function between the oral cavity sound pressure and a BCM. This paper try to explain the amplitude variation of bone-conducted speech and air-conducted speech depending on the vowel pronounced and highlights the inapplicability of Perceptual Evaluation of Speech Quality (PESQ) metrics for BCM. It opens avenues for signal processing techniques aimed at improving the quality and intelligibility of BCM-recorded speech. • Variation in mouth opening changes the transfer function between air and bone conduction microphones (TF0). • TF0 variation is due to changes in mouth radiation properties. • Variation in mouth opening does not change the transfer function between the oral cavity and BCM. [ABSTRACT FROM AUTHOR]

• This article presents the results of transfer function measurements of medium voltage sensors in broad frequency range. • The sensors tested are conventional voltage and current transformers, Rogowski coil and voltage sensors. • The article presents the numerical values of the models approximating the transfer functions of the sensors, allowing them to be used in simulations. This paper presents the test results of signal converters' ability to measure current and voltage at travelling wave frequencies. The transfer function models of the converters are developed and presented. In the literature the plots of the frequency characteristics of various types of converters can be found, but they are usually not supplemented with the specific numerical data or at least a transfer function model. In this paper, the authors intend to show stable transfer functions models of traditional transformers, Rogowski coils and voltage sensors for signals up to few megahertzes. The developed models can be used for the advanced simulations of the operation of protective relays, including those based on wave phenomena. These models can also be used for the analyses concerning power quality measurements. [ABSTRACT FROM AUTHOR]

Meta-heuristic algorithms play an essential role in solving real-world optimization problems. However, their performance is limited by the complexity and variability of the problems. Hence, various efficient algorithms are being actively explored. The exponential distribution optimizer (EDO), having attracted attention for its efficient search performance, has been extended to several applications. However, it suffers from falling into local optima and weak exploitation. Meanwhile, it cannot be directly applied to solve binary optimization problems. To address these challenges, this paper proposes an enhanced EDO called BOMLDEDO. The Bernstein-assisted oppositional-multiple learning strategy is proposed to avoid falling into local optimality. The Bernstein-based adaptive differential strategy is developed to improve exploitation capability. Moreover, by introducing a transfer function, repair method, and binary-to-real operation, BOMLDEDO is extended to a binary version. The IEEE (Institute of Electrical and Electronics Engineers) CEC (Congress on Evolutionary Computation) test functions and engineering problems are used to evaluate BOMLDEDO's optimization performance for continuous problems. Compared to its competitors, BOMLDEDO ranks first on more than 8 out of 10 IEEE CEC 2020 functions and more than 10 out of 12 IEEE CEC 2022 functions. Meanwhile, it achieves the global optimum in 91% of engineering problems. Furthermore, the 0–1 knapsack problems are applied to verify BOMLDEDO's binary optimization capabilities, and the results show that BOMLDEDO is successfully utilized in 14 knapsack instances. The above results demonstrate that incorporating multiple strategies helps improve the performance of BOMLDEDO, making it more reliable and applicable in solving continuous optimization problems and 0–1 knapsack problems. [ABSTRACT FROM AUTHOR]

This paper presents a design method for a Filter-Integrated Single Pole Double Throw (FI-SPDT) switch based on transfer function analysis. Combining the equivalent model of pseudomorphic High Electron Mobility Transistor (pHEMT) and its parasitic parameters, the proposed method analyzed the transfer function of the SPDT in both ON and OFF states. Consequently, it enables the rapid derivation of theoretical values for the active and passive structures, and thus offers theoretical support for the rapid design of cutoff frequency-controllable and high isolation FI-SPDTs. To validate the proposed design methodology, this paper employed a transfer function design method to calculate the theoretical values of the active and passive structure. Based on these theoretical values, an optimized design was carried out. Eventually, using the 0. 5 μ m GaAs pHEMT process, two FI-SPDTs were developed with cutoff frequencies of 4 GHz and 15 GHz, respectively. Measurement data demonstrates an insertion loss of 0.85 dB and 0.76 dB, with isolation ranging from 30–55 dB and 30–48 dB in the 4–15 GHz range. This further confirms the effectiveness of employing transfer function analysis for developing SPDTs with bandpass characteristics. Additionally, the method proposed in this paper is suitable for the intelligent design of microwave integrated circuits. [ABSTRACT FROM AUTHOR]

Radial applanation tonometry is a well-established technique for hemodynamic monitoring and is becoming popular in affordable non-invasive wearable healthcare electronics. To assess the central aortic pressure using radial-based measurements, there is an essential need to develop mathematical approaches to estimate the central pressure waveform. In this study, we propose a new Fourier-based machine learning (F-ML) methodology to transfer non-invasive radial pressure measurements to the central pressure waveform. To test the method, collection of tonometry recordings of the radial and carotid pressure measurements are used from the Framingham Heart Study (2640 individuals, 55 % women) with mean (range) age of 66 (40–91) years. Method-derived estimates are significantly correlated with the measured ones for three major features of the pressure waveform (systolic blood pressure, r =0.97, p < 0.001; diastolic blood pressure, r =0.99, p < 0.001; and mean blood pressure, r =0.99, p < 0.001). In all cases, the Bland-Altman analysis shows negligible bias in the estimations and error is bounded to 5.4 mmHg. Findings also suggest that the F-ML approach reconstructs the shape of the central pressure waveform accurately with the average normalized root mean square error of 5.5 % in the testing population which is blinded to all stages of machine learning development. The results show that the F-ML transfer function outperforms the conventional generalized transfer function, particularly in terms of reconstructing the shape of the central pressure waveform morphology. The proposed F-ML transfer function can provide accurate estimates for the central pressure waveform, and ultimately expand the usage of non-invasive devices for central hemodynamic assessment. • Radial tonometry aids hemodynamic monitoring. • The Fourier-based machine learning method estimates central pressure accurately. • The study correlates Fourier-based machine learning estimates with pressure features. • Fourier-based machine learning improves central hemodynamic assessment. [ABSTRACT FROM AUTHOR]

We theoretically demonstrate the possibility of generating a spatiotemporal optical vortex (STOV) beam in a dielectric slab waveguide. The STOV is generated upon reflection of a spatiotemporal optical pulse from an integrated metal–dielectric structure consisting of metal strips "buried" in the waveguide. For describing the interaction of the incident pulse with the integrated structure, we derive its "vectorial" spatiotemporal transfer function (TF) describing the transformation of the electromagnetic field components of the incident pulse. We show that if the TF of the structure corresponds to the TF of a spatiotemporal differentiator with a π / 2 phase difference between the terms describing temporal and spatial differentiation, then the envelope of the reflected pulse will contain an STOV in all nonzero components of the electromagnetic field. The obtained theoretical results are in good agreement with the results of rigorous numerical simulation of the STOV generation using a three-strip metal–dielectric integrated structure. We believe that the presented results pave the way for the research and application of STOV beams in the on-chip geometry. • Spatiotemporal optical vortices can be generated in a dielectric slab waveguide. • STOV generation is performed using an integrated metal–dielectric resonator. • STOV is generated upon reflection of a guided-mode pulse from the resonator. • The results pave the way for further research of STOVs in the on-chip geometry. [ABSTRACT FROM AUTHOR]

The biggest problem that electric or hybrid vehicles present today are the amount of time required to recharge their energy, hence the importance of ensuring that the charge is not lost quickly and reducing the recharging time. We propose a more efficient energy production model to maintain the charge of the battery banks in hybrid and electric vehicles so that the autonomy time increases. A direct current to direct current (DC-DC) converter was modeled, in a buck-boost configuration that can keep the voltage constant of 50VDC powering the battery bank, with input voltages ranging between 35 and 70VDC with a fixed charging current of 4A. To automatically determine the values of the discrete components of the power filter, a MATLAB® script was developed. The transfer function of the power filter controller was calculated and simulated in open and closed loops to analyze the converter's stability. The complete circuit was tested for possible variations in voltage and load current using a Pulse-Width Modulation (PWM), with a time base of 2.4 kHz. To demonstrate the ability to perform the same function of the converter in a more stable way, digital control by PWM was implemented on a Nexys 4 development board (FPGA, Field Programmable Gate Arrays). In addition, with the advantage of reducing the variations inherent in using discrete components in an electronic circuit. Herein we disclose 1. a high-level language computer program to estimate the value of the components of the power filter that performs the energy conversion; 2. the transfer functions of the system modules; 3. the simulation of the buck-boost DC-DC converter control system without polarity inversion; and 4. the simulation of the system in digital form implemented on an FPGA. [ABSTRACT FROM AUTHOR]

This paper illustrates the investigation of a higher-scale proton exchange membrane fuel cell (PEMFC) model to realize its performance, simulation analysis and design in terms of reduced order model. The present research aims to visualize the efficacy of the propounded student psychology based optimization (SPBO) approach in terms of different reduced order transfer functions with model order reduction (MOR) studies. The adopted methodology can reduce the obligations encountered by the higher-order model like stability, calculative effort and problem of trapping into local optima. In this paper, the efficacy of the employed approach is established by performing comparative analysis with the existing optimization approaches in terms of various performance indices such as in-depth frequency analysis and time-domain analysis. The MOR study implements the SPBO approach to accomplish its effectiveness for higher dimensional systems with less computational effort to validate the reliability and the robustness of the adopted strategy. The obtained results are related to the outcomes yielded by other optimization approaches reported during recent past. • In PEMFC, significance of MOR based met heuristic approach has been studied. • Investigation of SPBO devoted to PEMFC for higher-order reduction. • Performance of proposed approach at different operating cases has been explored. [ABSTRACT FROM AUTHOR]

Our aim through this paper is to describe a Krylov based projection method in order to reduce high-order dynamical systems. We focus on differential algebraic equations (DAEs) of index-2 that arise from spatial discretization of Stokes equations. An efficient algorithm based on a projection technique onto an extended block Krylov subspace that appropriately allows us to construct a reduced order system is described. Numerical results are provided to confirm the performance of the derived method compared with other known ones. [ABSTRACT FROM AUTHOR]

Paleoclimate proxy studies of wetland sediment cores often document the direction if not the magnitude of climate change because transfer functions (pollen, diatoms, etc.) are unavailable or imprecise. A water-budget approach, presented here, circumvents the need for transfer functions in wetlands, using the Garden Basin cattail fen (GBC; Fish Lake Plateau, Utah, USA) as a model system. Prior studies of the GBC fen revealed both high and low-frequency oscillations between fen and pond states over the last 12.5 ka. Pollen indicated that pond-like conditions were accompanied by both greater monsoon and annual precipitation rates. However, the magnitude of these changes was not estimated. By synthesizing multiple approaches, including water-level monitoring, remote sensing (normalized difference vegetation index, NDVI), and terrain analysis, limits were placed on precipitation changes required for pond versus fen ecosystems in Garden Basin. NDVI data show that water levels may be controlled by evapotranspiration (ET) instead of spring snowmelt. Water levels increase in mid-winter in response to the decline of photosynthesis of surrounding piñon-juniper (PJ) forest. In late summer through fall, ET drives the fen system into a moisture deficit and water declines below the ground surface. Quantitative limits on both annual and seasonal precipitation changes can be obtained through water budgets. For the GBC model, mean annual precipitation (~350 mm/yr) must double (~700 mm/yr) to sustain perennial standing water for 95% of years. Increases in late summer (monsoon) through fall (cyclonic) precipitation requires lesser rates (100–200 mm/yr) to satisfy PJ ET demands to maintain standing water. Thus, the habitats of many wetlands globally may be particularly sensitive to late-season precipitation where ET is the primary control on water levels. In summary, the GBC fen and its water budget are a template for quantifying the magnitude, rather than just the direction, of precipitation change in wetland systems through time. [ABSTRACT FROM AUTHOR]

South Korea has implemented borehole-type seismometers for reliable earthquake observations and earthquake early-warning systems, with approximately 85% of seismometers being replaced by borehole-type seismometers after the Gyeongju earthquake. Although these seismometers are more effective at detecting earthquakes owing to the reduced artificial ambient noise, they do not record surface-level shaking. Therefore, it is necessary to estimate ground surface shaking directly associated with potential damage when using borehole-type seismometers without surface sensors. This study investigated and compared various methods, including the stochastic point-source ground-motion model, transfer function based on ambient noise, and one-dimensional site response, to estimate horizontal seismograms of the ground surface. We assessed the accuracy of these methods by comparing the waveforms generated in event cases (magnitude from 2.5 to 5.8, with epicentral distances spanning 22 km–209 km) in terms of Fourier spectra, intensity, and spectral acceleration. Among the methods assessed, the transfer function approach, which does not account for the geophysical characteristics such as V S 30 , proved to be the most appropriate for correcting ground-surface effects. • Estimating seismic intensity measurements (IMs) at ground surface from borehole seismometers. • Approach for estimating IMs without ground surface seismometers. • Comparing methods: ambient noise transfer, point-source models, and 1D site response. [ABSTRACT FROM AUTHOR]

Convolution equations are used to relate the input and the output of a system such as rainfall and runoff, or inflow and outflow of a river reach. There have been numerous reports of unsatisfactory results from the deconvolution necessary to calculate the connecting transfer function. The cause is that the equations are ill-conditioned, and it is shown here that the fundamental theoretical solution is that of wild oscillations such as has often been found computationally. A spectral method is proposed for numerical solution, where, instead of individual point values, the transfer function is expressed as series of given continuous functions, where the problem is to determine the coefficients of those functions. The resulting equations have been found to be well-conditioned, and solutions obtained were smooth, bounded, and enabled a certain amount of physical interpretation of the transfer function. The method has been applied to several problems, including typical rainfall–runoff ones and flood routing and wave propagation problems, with quite satisfactory results. Another problem for deconvolution is found to be the traditional use of truncated equations. A remedy is only to use later output data points where convolution with input data does not reach back beyond the initial one. For the routing of larger flood events, the linear methods employed were found to be not so accurate. However as they are a first approximation that requires no knowledge of stream geometry or resistance, and as either discharge or water level hydrographs can be used, they may be useful. • System identification, deconvolution, has always been problematical. • A new computational method is suggested that overcomes problems. • Results are good, giving smooth bounded system functions. • A useful technique for simulation where river properties are not known. • For large floods, problem nonlinearity means results are not as accurate. [ABSTRACT FROM AUTHOR]

Soil-structure interaction is a key aspect when calculating the dynamic response of nuclear structures in front of ground motions induced by earthquakes. However, modelling the seismic response in the time-domain using FEM-based models to represent the soil volume is computationally expensive because of the large number of elements involved. For this reason, it is a common practice to employ 1-D models, which allows an explicit solution of the dynamic response of the system in a fraction of time. Yet, due to the importance of nuclear structures, sometimes it is mandatory to employ 3D FEM-based models. In addition, based on probabilistic estimations of the seismic hazard at a site, it is generally necessary that the seismic response of the model comply with the spectral ordinates of the input action at the surface level. In doing so, specific accelerograms acting at the bedrock should be developed. If these signals are obtained by deconvolution using the 1D model, and then applied to the 3D one, the response calculated at the surface level will always be somewhat different from the target free field motion (the one considered in the deconvolution process at the surface level). There are several sources, like the Poisson effect in the 3D model, explaining this difference. Therefore, it is necessary to modify the input signal so that the dynamic response obtained with the FEM model fit the target spectrum. This article presents an innovative approach to achieve this goal, developing an enhanced transfer function stemming from the 1D and 3D models. Two seismic scenarios and a specific soil profile have been used as benchmark. Results show that this approach provides an adequate solution for the studied problem. • Soil-structure interaction is a key aspect when calculating the seismic response of nuclear structures. • Modelling this response in the time-domain using FEM models to represent the soil volume is computationally expensive. • The seismic response of the model must comply with specific spectral ordinates related to the hazard of the site. • This article presents an innovative approach to achieve this goal, using an enhanced transfer function from 1D and 3D models. • Two seismic scenarios and a specific soil profile have been used as benchmark. • Results show that this approach provides an adequate solution for the studied problem. [ABSTRACT FROM AUTHOR]

The estimation of thermo-physical properties of materials at high temperatures requires the development of robust and fast-enough direct models that takes into account the strong coupling between conduction and radiation. The interest in using the Monte Carlo method to obtain a conduction–radiation model in a semi-transparent material solved in a reduced computational time is addressed in this study. An academic configuration that consists of an absorbing/emitting and non-scattering gray medium with steady-state conduction is investigated since this study is meant to be a proof of concept. It is demonstrated that the radiative source term of the heat equation may be estimated as a function of the temperature field to the fourth power, using a Finite Differences algorithm and a single Monte Carlo simulation of radiation. The results of the numerical study show that, on the one hand, they are in good agreement with those found in the literature and, on the other, that the coupled model can be resolved in a significantly shorter amount of computational time than with traditional methods thanks to the functional estimation of the radiative source term. In fact, in each of the fifteen analyzed cases, the coefficients of the function were determined in approximately 6 s using the Monte Carlo method using a laptop with standard computational resources. The computation of the function and its application revealed that, depending on the studied configuration, a resolution with the finite differences–functional Monte Carlo algorithm can be around twenty to one thousand times faster than a classic Finite Differences–Monte Carlo algorithm. Due to these characteristics, as well as the fact that the functional estimation is insensitive to geometry complexity and can be extended to configurations with heterogeneous radiative properties, it becomes possible to utilize this method in inversion procedures, since the direct model must be evaluated numerous times. • Semi-transparent media characterization requires fast coupled heat transfer resolution. • The functional estimation of the radiative source term with reduces computational time. • Functional estimation does not compromise physics or geometrical complexity. • This fast direct model resolution algorithm demonstrates promising features for its using in inversion procedures. [ABSTRACT FROM AUTHOR]

In pursuit of innovating the conventional powder-pack boriding (CPB) process by introducing an electrical driving force, novel findings regarding the kinetics growth of boride layers produced on an AISI 8620 steel through the pulsed-DC powder-pack boriding process (PDCPB) were obtained. The PDCPB accelerates B diffusion on the surface of the specimen, resulting in an augmentation of the growth kinetics around 12 % and 15 % for FeB and Fe 2 B, respectively, compared to those observed in the CPB process. Additionally, the effect of polarity inversion half-cycles on the growth of the FeB-Fe 2 B layer during the PDCPB was studied. The experiments were conducted at temperatures of 850 °C, 900 °C, and 950 °C, with different exposure times, and polarity inversion half-cycles of 30 s and 50 s, maintaining a constant current density of around 177 mA cm−2. An estimation of the electric charge (q) using a transfer function considering minimal and maximum temperatures was achieved. It was confirmed that, with a symmetrical inversion, q was similar for both 30 s and 50 s polarity inversion half-cycles, indicating no influence on the growth kinetics of the boride layers. • Each component of boriding media influenced its electrical behavior during PDCPB. • A holistic explanation of the boriding media electrical behavior was developed. • Transfer function was used for the estimation of electric charge during PDCPB. • Similar electric charge was obtained for half-cycles >7 ms. • Electric charge did not influence the boride layer growth kinetics. [ABSTRACT FROM AUTHOR]

Modular assembly techniques for ultra-high lattice wind turbine support structures are gaining popularity as a viable solution for wind energy development in low wind speed areas. However, efficient fatigue assessment of the overall structure is crucial for the widespread promotion and application of these structures. Existing engineering methods for fatigue assessment suffer from limitations in calculation efficiency and often fail to account for the effects of average stress. To address these issues, a novel integrated fatigue assessment method is proposed, which is both fast and efficient while considering the impact of average stress. The method enables the computation of cumulative fatigue damage and fatigue life for each component, as well as the identification of the location of the greatest cumulative fatigue damage in the structure. An onshore ultra-high lattice wind turbine support structure, modularly assembled to a height of 180 m, is utilized as an application example to illustrate the specific implementation process of the proposed method. The effect of different fatigue load conditions and transfer functions on cumulative fatigue damage is analyzed, and the relationship between transfer function and fatigue accumulation damage is examined. The findings indicate that average stress plays a crucial role in the cumulative fatigue damage of ultra-high lattice wind turbine support structures, and the proposed integrated fatigue assessment method simplifies the calculation process for fatigue-resistant designs substantially. • Novel fatigue assessment considers average stress in wind turbine structures. • Implemented approach detailed in a real wind turbine project case study. • Explored the impact of various average stress correction methods on fatigue damage. • In-depth exploration of the link between transfer function and fatigue damage. [ABSTRACT FROM AUTHOR]

• Description of FRA amplitude and phase angle curves using the mathematical equations derived by processing the measured FRA data. • Interpretation of peaks and troughs in FRA curves using the parameters of the derived transfer function equations. • Explanation of ripples in FRA curves using the derived transfer function equations based on measured FRA data. • Characterization of low-frequency FRA curves using the derived transfer function equations based on measured FRA data. Mechanical malfunctions pose a significant threat to the reliability of power transformers. Frequency Response Analysis (FRA) of transformer windings (TWs) serves as a predictive technology, allowing the assessment of mechanical conditions based on collected FRA data. Changes in the winding structure manifest in FRA characteristics, making it possible to detect incipient faults. This paper presents the derivation of transfer functions (TF) equations through processing FRA data, aiming to investigate and interpret the characteristics of TWs. The derived TFs are utilized to mathematically describe FRA curves, enabling the characterization of winding structures by observing the FRA curves generated from these TF equations. Not only do the derived TFs yield very similar FRA curves, but the TF estimation also provides valuable insights for assessing TW malfunctions. The similarity analysis, using calculated RMSE and MAE values of 0.4807 and 0.2020, respectively, demonstrates a strong correlation between the derived TF curves and the measured FRA curves. This affirms the validity of TF estimation and underscores its significant impact on the advancement of FRA technology. [ABSTRACT FROM AUTHOR]

Estimates of food-insecure populations are biased upwards, lacking adjustment for global increases in sedentary behavior in recent decades. We construct a household model to account for sedentary choices during leisure and work time decisions. The model rationalizes increasing sedentary behavior from the household by accounting for increasing returns to cognitive human capital vs physical capital, alongside increased productivity of more sedentary activities both at work and at home. The household model informs an empirical model applied to our unique international pseudo-panel data on sitting time, proxy-ing for sedentarism. We econometrically estimate a transfer function linking sedentarism to widely available covariates and make out-of-sample predictions. It is applicable to most countries. The estimated sedentary time can be used to adjust the physical activity level reflected in the minimum dietary energy requirement used to determine a cutoff for food insecurity. • Estimates of global food security using the PoU are biased upwards due to lower physical activities in the last 3 decades. • This bias underlies influential estimates of food insecurity generated by FAO, USDA, and other agencies. • We construct a scalable and implementable method to account for increases in sedentarism and adjust caloric cutoffs. • Those cutoffs, minimum dietary energy requirements (MDERs), become time and country specific. • Our approach uses available covariates and a pseudo-panel dataset to estimate coefficients included in transfer functions. • We predict changes in mean hourly sitting time for a given nation and timespan. • The predicted sitting time is incorporated in the physical activity level underlying the MDER to adjust it downward. • MDER inflation in food insecurity estimates is 33 to 91 calories per day for a young adult male of 65 kg. [ABSTRACT FROM AUTHOR]

Since the introduction of bender element tests to soil testing, the reliability of the estimated travel time has been the most serious problem. The author has previously shown a potential solution whereby removing the response of the bender element subsystem from the whole response could dramatically improve the accuracy of the travel time estimation. In order to lay the foundation for estimating the response of the bender element subsystem, this paper examines the correlation between the displacements of the element and the induced feedback signals by employing a self-monitoring element. The response of the self-monitoring element is modeled as a transfer function involving two internal transfer functions that relate the input signals to the displacements and the displacements to the feedback signals, respectively. Using a laser displacement sensor, the displacements are directly measured through the entire surface and reveal the three-dimensional bending motion of the element oscillating in both longitudinal and width directions. The feedback signals are similar to, but inconsistent with, the tip displacements, and an attempt is made to correct the feedback signals. Finally, a conclusion is given on the potential for estimating the response of the bender element subsystem using the self-monitoring element. [ABSTRACT FROM AUTHOR]

Artificial neural network model was developed to obtain the fluid outlet temperature of the parabolic trough collector (PTC) with a grooved absorber tube. To improve the accuracy of the model, an analysis of the transfer functions was performed at different normalization intervals to choose the best model capable of estimating the PTC outlet temperature. A first model was developed that was used as a base model from 1,155 concordant experimental data. The variables were input temperature of the fluid, ambient temperature, irradiance, hour, day, configuration, volumetric flow, feeding temperature, and storage temperature. To validate the accuracy and the adaptability of the model proposed, statistical tests (coefficient of determination (R2), root mean square error (RMSE), and mean absolute percent error (MAPE), significance test (F-Fisher and t-student), and linearity test (slope-intercept)) were performed. The base model was validated, having an R2 = 0.9961, RMSE = 0.14706, MAPE = 0.00795, also approved significance and linearity tests. Consequently, ten models were developed for the analysis of the proposed normalization intervals using the same architecture as the base model at five areas of interest with a hyperbolic tangent sigmoid (TANSIG) and log-sigmoid (LOGISIG) functions. The results show that a model has higher accuracy; this model was the TANSIG of [0.1,0.9] with R2 = 0.9974, RMSE = 0.12123, MAPE = 5.93 × 10-5, and approved significance and linearity. [ABSTRACT FROM AUTHOR]

In the last past year researchers have relied on the ability of Laplace transform to solve partial, ordinary linear equations with great success. Important analysis in signal analysis including the transfer function, Bode diagram, Nyquist plot and Nichols plot are obtained based on the Laplace transform. The output of the analysis depends only on the results obtained from Laplace transform. However, one weakness of Laplace transform is that the Laplace transform of even function is odd while the Laplace transform of an old function is even which is lack of conservation of properties. On the other hand there exist a similar integral transform known as Sumudu transform has the ability to conserve the properties of the function from real space to complex space. The question that arises in the work, is the following: Can we apply the Sumudu transform to construct new transfer functions that will lead to new Bode, Nichols and Nyquist plots? this question is answered in this work. [ABSTRACT FROM AUTHOR]

Lidar based wind measurement is an integral part of wind farm control. The major issues and challenges in power maximization include the potential losses due to wake effect observed among wind turbines. This manuscript presents a wake management technique that utilizes lidar simulations for wake redirection. The proposed methodology is validated for 2-turbine and 15-turbine wind farm layouts involving a PI control based yaw angle correction. Yaw angle misalignment using wake center tracking of the upstream turbines is used to increase the power generation levels. Results of wake center estimation are compared with a Kalman filter based method. Further, the velocity deficit and overall farm power improvement by yaw angle correction is calculated. Results reveal a 1.7% and 0.675% increase in total wind farm power for two different wind speed cases. • Lidar assisted wake control is studied. • Transfer function-based methodology for wake center control is proposed. • Wake center control for multiple wind turbines is presented. • Methodology is validated for two wind speed scenarios for a 15-turbine farm layout. • Power improvement in non-yawed and yawed mode is studied. [ABSTRACT FROM AUTHOR]

In this paper, performance analysis of second order analog filters using Remote Laboratory is presented. The Remote laboratory system developed indigenously has the many analog experiments that can be conducted by authorized user from anywhere at any time. The remote laboratory system also has second order Low pass filter (LPF) and High pass filter (HPF). It possible to perform filter experiments with three different values of resistors, two capacitors with different values. Along with this there is option of modifying the voltage gain of the filter. This will enable the user to analyze the filter performances thoroughly. Both time and frequency response are obtained to determine pass band gain, pole and zero locations and the roll-off the filter. Using this user can know the effect of voltage gain on the circuit and obtain maximally flat response also. Remote laboratory system for filters is built using an ingeniously developed PCB and uses Arduino board for selecting and switching experiments and Analog Discovery a product ot National Instruments is used for applying and measuring the signals during the conduction of experiments. The user has the freedom in applying signals of desired signals. Paper also presents typical analysis report of filters conducted remotely. [ABSTRACT FROM AUTHOR]

In a recently conducted study, we developed a nano-particle sizer (NPS) that consists of a multi-port differential mobility analyzer (MP-DMA) and two multi condensation particle counters (M-CPCs) for achieving fast measurements of aerosol particles; however, the performance of MP-DMA was not detailed in the study. Therefore, the objective of this study is to perform numerical simulations to obtain the transfer function of each port in the MP-DMA, which is the main component of the NPS. We observed good agreement between the numerically obtained central particle size of each port and the experimental data under the same operating conditions. The transmission probability and resolution of each port were determined and analyzed under various conditions using the transfer function. The findings of this study shall help in understanding the advantages of NPS. Unlabelled Image • Simulations on the MP-DMA in the newly developed real-time NPS were conducted. • A Lagrangian particle tracking with a flow rate weighted method was used. • Transfer functions of the MP-DMA were obtained for the performance evaluation. • Numerical transmission probability decreases with the increasing port number. • Increasing half-width of transfer function due to reducing aerosol/sheath ratio. [ABSTRACT FROM AUTHOR]

Currently there are few studies on modern diatom ecology in large lakes on the Tibetan Plateau. To illustrate spatial patterns of diatom communities and study the correlation with environmental variables, 143 surface sediments were sampled from the largest lake (Selin Co) on the central Tibetan Plateau. A total of 143 diatom species belonging to 30 genera were identified, most of which were halophilic and basophilic species. Our results show that diatom communities exhibit a distinct spatial pattern in different environments including fluvial rivers, the inlet of Selin Co, the small lake region and the large lake region of Selin Co. Based on a depth-constrained cluster analysis, the diatom taxa were divided into three different communities: the shallow sedimentary zone (0–12 m), middle sedimentary zone (12–22 m) and deep sedimentary zone (22–48 m). The dominant species were Cocconeis placentula , Nitzschia hungarica and Anomoeoneis costata respectively. Through Canonical correspondence analysis, it was indicated that the spatial distribution of the diatom assemblages was mainly influenced by water depth, grain size and temperature, with water depth being the dominant factor. WA-PLS and WA regression models were used to establish a diatom-depth transfer function (r2 boot = 0.73, RMSEP = 0.19; r2 boot = 0.76, RMSEP = 0.19), further demonstrating the correlation between the diatom community and water depth. Our results defined the spatial distributions and controlling factors of diatom assemblages from the different environments. [ABSTRACT FROM AUTHOR]

• Understanding the acoustic pressure generated by ultrasound transducers is essential for evaluating their performance. • Traditional methods used to determine the transmit transfer function of ultrasound transducers can be both expensive and complex. • The acoustic power emitted by ultrasound transducers can be estimated by analyzing the phenomenon of acoustic streaming. • The motion associated with acoustic streaming can be measured without the need for intricate techniques such as particle image velocimetry or Doppler ultrasound. The accurate determination of the transfer function of ultrasound transducers is important for their design and operational performance. However, conventional methods for quantifying the transfer function, such as hydrophone measurements, radiation force balance, and pulse-echo measurements, are costly and complex due to specialized equipment required. In this study, we introduce a novel approach to estimate the transfer function of ultrasound transducers by measuring the acoustic streaming velocity generated by the transducer. We utilize an experimental setup consisting of a water tank with a millimeter scale, an ink-filled syringe, and a camera for recording the streaming phenomenon. Through streaming velocity measurements in the frequency range from 2 to 8 MHz, we determined the transfer function of an unfocused circular transducer with a center frequency of 5 MHz and a radius of 5.6 mm. We compared the performance of our method with hydrophone and pulse-echo measurements. At the center frequency, we measured a transmit efficiency of 1.9 kPa/V using the streaming approach, while hydrophone and pulse-echo measurements yielded transmit efficiencies of 2.1 kPa/V and 1.8 kPa/V, respectively. These findings demonstrate that the proposed method for estimating the transfer function of ultrasound transducers achieves a sufficient level of accuracy comparable to pulse-echo and hydrophone measurements. [ABSTRACT FROM AUTHOR]

In this short communication, the residence time distribution of molten polymer in a liquefier of a material extrusion process is numerically investigated. The Laplace transform is used to easily fit the residence time distribution. As a result, the liquefier can be decomposed into a plug flow and a continuous stirred tank reactor in series. The local mean residence time is also studied numerically to provide information about the flow structure. [ABSTRACT FROM AUTHOR]

• Proposing a novel fuzzy transfer function based on the Mamdani fuzzy inference system for BPSO. • Comparing the performance of fuzzy transfer function with other transfer functions for BPSO and some recent state-of-the-art of binary meta-heuristic algorithms for high-dimensional feature selection problems. • Achieving the optimal subset of features with high accuracy in datasets by the FBPSO. Many discrete optimization problems are in the class of NP-hard problems; therefore, exact algorithms cannot achieve an optimum solution in reasonable time. Approximate algorithms like binary meta-heuristic algorithms have provided good results in these problems. Since many meta-heuristic algorithms have been introduced for continuous search spaces, employing a transfer function is one of the simplest methods to map the search space to the binary one. Many transfer functions have been introduced, divided in atomic and compound transfer functions. In the atomic transfer functions, a single function is applied in the algorithm, such as S-shaped, U-shaped, V-shaped, Z-shaped and so on. Compound transfer functions employ more than one atomic transfer function in their structures, such as Mirrored Time-Varying S-shaped, χ-shaped, and Upgrade transfer functions. An improper transfer function decreases the algorithm's performance in the binary search space. Hence, several transfer functions are usually evaluated for solving a binary problem to select the best one. In this study, a fuzzy transfer function is proposed and applied in Binary Particle Swarm Optimization (FBPSO). The behavior of PSO is analyzed, and the fuzzy transfer function and its rules create a new binary position. The performance of atomic and compound transfer functions employed in BPSO and some recently introduced binary meta-heuristic algorithms are compared with FBPSO in high-dimensional feature selection problems. The experimental results show that FBPSO achieves the best solution in terms of minimum error and feature selection rate compared with other comparative algorithms. [ABSTRACT FROM AUTHOR]

Identification of the optimal subset of features for Feature Selection (FS) problems is a demanding problem in machine learning and data mining. A trustworthy optimization approach is required to cope with the concerns involved in such a problem. Here, a Binary version of the Capuchin Search Algorithm (CSA), referred to as BCSA, was developed to select the optimal feature combination. Owing to the imbalance of parameters and random nature of BCSA, it may sometimes fall into the trap of an issue called local maxima. To beat this problem, the BCSA could be further improved with the resettlement of its individuals by adopting some methods of repopulating the individuals during foraging. Lévy flight was applied to augment the exploitation and exploration abilities of BCSA, a method referred to as LBCSA. A Chaotic strategy is used to reinforce search behavior for both exploration and exploitation potentials of BCSA, which is referred to as CBCSA. Finally, Lévy flight and chaotic sequence are integrated with BCSA, referred to as LCBCSA, to increase solution diversity and boost the openings of finding the global optimal solutions. The proposed methods were assessed on twenty-six datasets collected from the UCI repository. The results of these methods were compared with those of other FS methods. Overall results show that the proposed methods render more precise solutions in terms of accuracy rates and fitness scores than other methods. • Binary capuchin search algorithm is used for the first time for feature selection. • Three other versions of BCSA are also proposed for feature selection. • The results revealed that BCSA has high efficiency over the 26 datasets. • The proposed methods are compared with 16 well-known optimization methods. • BCSA shows high classification accuracy and few number of selected features. [ABSTRACT FROM AUTHOR]

To assess whether vertebrobasilar artery ischemia (VBI) affects cortical cerebral blood flow (CBF) regulation. 107 consecutive patients (mean age 65 ± 15 years; women 21) with VBI underwent structured stroke care with assessment of dynamic cerebral autoregulation (dCA) in both middle cerebral arteries (MCAs) by transfer function analysis using spontaneous oscillations of blood pressure (BP) and CBF velocity that yields by extraction of phase and gain information in the very low (0.02-0.07 Hz), low (0.07-0.15 Hz) and high frequency (0.15-0.5 Hz) ranges. Additionally, power spectrum analysis of BP and heart rate variability (HRV) was performed. The control group consists of 29 age- and sex-matched healthy persons. Compared to controls, phase in the VBI patients was significantly reduced and gain increased in the very low frequencies (VLF), in the low (LF), phase was significantly reduced only ipsilaterally. In the high frequencies (HF), phase reduction was only marginally significant. BP power spectral density (PSD) was much higher in the patients than in the controls across all frequencies. In the PSD of heart rate variability the controls but not the patients exhibited a strong peak around 0.11Hz, while the patients, but not the controls, exhibit a strong peak around 0.36 Hz. In regression analysis, patient's phase and gain results were not related to age, sex, arterial hypertension, diabetes mellitus, renal dysfunction, heart failure as indicated by left ventricular ejection fraction, stroke subtype, presence or absence of cerebral small vessel disease. Patients with VBI exhibit bilateral cortical autoregulation impairment in association with an autonomic nervous system disbalance. NCT04611672 [ABSTRACT FROM AUTHOR]

Direct volume rendering (DVR) helps data interpretation by allowing users to focus attention on specific regions in a volume that are of most interest. The effective generation of these regions of interest (ROIs)-based DVR images, however, still remains a major challenge. It involved the intricate process of assigning appropriate optical parameters (opacity and/or color) to the ROIs and other regions in the volume using transfer function (TF) specification. Achieving an optimal TF often requires multiple iterations of a trial-and-error process, starting from scratch in each case, which is time-consuming and labor-intensive. To address this issue, there have been various TF optimization approaches, which could automatically fine-tune an initial TF toward an optimal solution satisfying a pre-defined objective metric. Although effective, the previous objective metrics exhibit two inherent limitations: (i) they were only capable of optimizing ROIs along an individual viewing ray of the volume, and the relationship with neighboring ROIs (as context) from other rays could not be controlled; (ii) the TF parameters to be optimized were restricted to opacity (i.e., the observability of ROIs) and did not include color which is also important to enhance the visual distinction of ROIs. In this work, we propose a new TF optimization approach by introducing an objective metric using visual saliency. Visual saliency is a biologically-inspired measure to aid the identification of ROIs considered important relative to other regions within an image according to the human visual system. Our novel adoption of visual saliency enables the TF optimization to take into account all ROIs in a volume (with its rendered image) implicitly. In addition, both opacity and color parameters can be applied to the TF optimization. Given the user-assigned target visual saliency of ROIs, our approach can produce more controllable and complete ROIs-based DVR images. We outline our approach by applications to a variety of volumetric datasets and highlight its advantages in comparison to the dominant TF optimization approaches that use visibility-based objective metrics. • We proposed a transfer function (TF) optimization approach using a new objective metric. • We adopted the core idea of visual saliency for use in identification of region of interest. • We evaluated the capability of our approach by comparing previous counterparts. [ABSTRACT FROM AUTHOR]

• A novel design for a tunable electrostatic phase plate without unwanted charging is presented. • The basis of the phase plate is the phase shift due to the electrostatic potential produced by negatively charged particle beams traversing a focal plane of the TEM. • In simulations I show that faithful high resolution images with good contrast can be recorded using such a phase plate. [ABSTRACT FROM AUTHOR]

Abstract The frequency response of three lean methane/air flames submitted to flowrate perturbations is analyzed for flames featuring the same equivalence ratio and thermal power, but a different stabilization mechanism. The first flame is stabilized by a central bluff body without swirl, the second one by the same bluff body with the addition of swirl and the last one only by swirl without central insert. In the two last cases, the swirl level is roughly the same. These three flames feature different shapes and heat release distributions, but their Flame Transfer Function (FTF) feature about the same phase lag at low frequencies. The gain of the FTF also shows the same behavior for the flame stabilized by the central insert without swirl and the one fully aerodynamically stabilized by swirl. Shedding of vortical structures from the injector nozzle that grow and rollup the flame tip controls the FTF of these flames. The flame stabilized by the swirler-plus-bluff-body system features a peculiar response with a large drop of the FTF gain around a frequency at which large swirl number oscillations are observed. Velocity measurements in cold flow conditions reveal a strong reduction of the size of the vortical structures shed from the injector lip at this forcing condition. The flame stabilized aerodynamically only by swirl and the one stabilized by the bluff body without swirl do not exhibit any FTF gain drop at low frequencies. In the former case, large swirl number oscillations are still identified, but large vortical structures shed from the nozzle also persist at the same forcing frequency in the cold flow response. These different flame responses are found to be intimately related to the dynamics of the internal recirculation region, which response strongly differs depending upon the injector used to stabilize the flame. [ABSTRACT FROM AUTHOR]

Indoor air humidity has a significant impact on indoor air quality, building energy consumption, and equipment performance. Excessively low or high humidity is not good for living and working. Hygroscopic materials can be used to moderate the indoor air humidity level. This paper presents a simplified dynamic moisture transfer model of building wall layer of hygroscopic material, and the parameter identification of the simplified model with genetic algorithm by comparing the frequency characteristics of the simplified model with the theoretic frequency characteristics. The proposed simplified model was validated against the published experimental measurements on the system level. The results show that the predicted moisture flux by the simplified model agrees well with the experimental test. The simplified model was also validated on room level by a common exercise in IEA 41 project. The results show that the simplified model has a good agreement with the analytical solution, within ±2.2% in the case CE1A. In the realistic case CE1B, the model prediction matches the results of these detailed models provided in public literature. The proposed simplified dynamic moisture transfer model can be used in building indoor humidity environment and energy consumption simulation with good accuracy and efficiency. • Developing a simplified dynamic moisture transfer model of building wall layer of hygroscopic material. • Model parameters are identified in the frequency domain by the basic material properties. • Validated against the published experiment measurements as well as by a published benchmark exercise. • Much more accurate than the EMPD model and more efficient than the CFD model. • Can be easily integrated into conventional simulation software, such as Simulink or TRNSYS etc. [ABSTRACT FROM AUTHOR]

Landslides are an important natural phenomenon of the flysch Outer Western Carpathians that diversify the local topography and provide valuable microrefugia in the geomorphologically uniform region. For the first time, we reconstructed the continuous history of Carpathian landslide wetland – the Kotelnice mire, which initiated at the Pleistocene-Holocene transition, using joint analysis of abiotic proxies, pollen, plant macrofossils and testate amoebae (TA). We utilised modern training datasets of plants and TA to define ecological requirements of species and to determine indicators of either bog or fen habitats. We further compared pollen representation of selected woody species between two landslide-related wetlands and two spring fens, not related to landslides within the study region. The unique feature of the Kotelnice mire is the development of a nearly ombrotrophic bog at ∼2500 cal BP that was after ∼1500 years reversed to a poor fen by intense deforestation and pastoralism. Pollen analysis and its intra-regional comparison demonstrate a dual refugial role of landslides in the Carpathians. In the Early Holocene and perhaps even in the Late Glacial, landslides provided refugia for warmth- and moisture-demanding species (e.g. lime, elm, hazel, beech, maple). On the contrary, they provided shelter for cold-demanding boreal species (e.g. spruce, Eriophorum vaginatum , Sphagnum medium / divinum) in the Middle and Late Holocene. Because the analogous refugial role of landslides at both the recent and the Quaternary time scales has been reported from the flysch-like and volcanite bedrocks across the Northern Hemisphere, landslides deserve more attention in searching for regionally or even globally crucial refugia. • Landslide wetland deposits witness landscape changes since the Late Glacial. • Landslides may support heterogeneity and refugial survivals in the Carpathians. • At the Holocene onset, mesophilic trees were more common in landslide areas. • In the studied landslide wetland, a nearly raised bog developed at ∼2500 cal BP. • Deforestation and pastoralism reversed the bog back to a poor fen ∼400 years ago. [ABSTRACT FROM AUTHOR]

This paper presents the first results of the quantitative reconstruction of ice conditions in the Arctic based on a comparison of the data for periods of meteorological observations with variations in the chemical compositions of the sediments accumulated during the same times. The biogenic elements (Br, Ca, and Sr) and some redox-sensitive (As and Fe) elements are the most informative for the reconstruction of changes in ice conditions with positive correlations, and the lithogenic elements (K and Ti) are predominantly negatively correlated. The reconstruction results for the last 300–400 years of average annual air temperature anomalies for all cores in general terms coincide with the reconstruction for the Northern Hemisphere. The common features of all reconstructions are low temperatures during the Little Ice Age (LIA) and a rapid warming in the middle of the 19th century and in the last decades of the 20th and first decades of the 21st centuries. The results of the reconstruction of the duration of the ice-free period generally coincide with the temperature changes for the last two centuries, although for LIA there is an inverse correlation between the variations in temperature and the duration of the ice-free period. A possible reason for this may be changes in the structure of the surface currents in the Chukchi Sea and the northern part of the Bering Sea, because of which the inflow of warm and freshened waters through the Bering Strait to the Arctic increased occasionally. [ABSTRACT FROM AUTHOR]

• A simplified transfer function approach based on grain scattering induced signal noise. • PoD curve estimation for materials with low SNR using experiments on materials with high SNR values. • Transfer PoD for stainless steel, aluminium and mild steel using experimental data of one among the others. In recent years several methods for reducing the burden of experimentation for obtaining Probability of Detection (PoD) curves have been proposed, especially involving the use of numerical simulation. In particular, there is much interest in being able to estimate the PoD capabilities of a given NDE method, target embodiment and material, provided this is known for some canonical material for the same combination of method/embodiment. Ultrasonic experiments on materials with low signal to noise ratio (SNR) are often difficult and time consuming since the higher signal noise causes serious complications. Set in this context, this paper proposes an approach for transferring PoD curves among materials with different SNR values. The classical transfer function PoD approach is based on the hypothesis that the ratio of signals in related quadrants is equal, which requires large datasets for multiple quadrants. The approach proposed here directly deals with SNR instead of the ratio of signals, and thus requires only the experimental data of the parent application. The new approach is illustrated through example cases involving the prediction of PoD curves for ultrasonic inspection of an aluminium plate using the empirical PoD data for the same in austenitic stainless steel and mild steel. The approach is also demonstrated in each of the possible combinations among these three materials. [ABSTRACT FROM AUTHOR]