Fluctuation Level Research Articles

An Improved Wavelet Threshold Denoising Method for Health Monitoring Data: A Case Study of the Hong Kong-Zhuhai-Macao Bridge Immersed Tunnel

Tunnels generally operate underground or underwater in a complex environment. As a result, the health monitoring system is inevitably affected by various environmental factors, which introduces noise to the system. However, the noise contained in the monitoring sequence may disrupt structural damage identification and health state assessment as the real structural response may be overwhelmed by the noise. To properly eliminate the noise in an objective way, this study proposed an improved wavelet threshold denoising method. Firstly, it adopts a quantitative factor, namely the Sparse Index, to assist the selection of the best wavelet basis in numerous wavelet packages. Then, the decomposition layer and threshold are optimized by a comprehensive evaluation based on a variation coefficient method. At last, the application of the concrete strain health monitoring data of the Hong Kong-Zhuhai-Macao Bridge immersed tunnel verified the effectiveness of the proposed method. It is found that the combination of sym12 and five decomposition layers can obtain the best denoising results within the selected wavelet families and decomposition levels. Moreover, the proposed method achieves good denoising results under different fluctuation levels. Thus, the proposed method is reliable, can solve the problem of optimal parameter selection such as decomposition level and wavelet basis in wavelet denoising, and can be applied in the structural health monitoring of critical infrastructures.

Experimental demonstration: Differential detection of 10 Gbps optical OOK signal over turbulent channel

In this paper, we experimentally demonstrate the bit error rate (BER) performance of fixed threshold differential detection for both 5 Gbps and 10 Gbps On-Off keying (OOK) signals over a turbulent channel, which induces slowly varying intensity fluctuation on the signals. The experimental results are also validated using numerical simulations. This study is significant for the terrestrial free-space optical (FSO) communication system in which the channel induces similar intensity fluctuation due to atmospheric turbulence. To show the efficiency of the differential detection scheme for the OOK signal two proof-of-principle systems are realized. In the first system, the effect of channel-induced intensity variation on the data is realized by passing a differentially coded OOK signal through a Mach–Zehnder modulator (MZM), which is driven by a low frequency sinusoidal electrical signal emulating slowly varying channel fluctuation. The amplitude of the sinusoid has been varied to create different levels of intensity fluctuation, mimicking different turbulent conditions in the optical link. In the second setup, we measure the BER performance of differential detection assisted OOK transmission over a short-range (10)m FSO channel, which is affected by turbulence-induced intensity fluctuations. The different turbulences are created by different heating levels of a blower, which injects hot air across the FSO channel. Experimental results show that in the presence of intensity fluctuation, differential detection of OOK signal using a fixed threshold offers a better BER performance at higher optical to signal ratio (OSNR) values compared to conventional direct detection (DD) scheme. Results obtained from numerical simulation of OOK transmission over turbulent FSO channels also confirm the similar behavior. Both simulation and experimental results show that differential detection can offer a BER of 10−3 at 5 Gbps and 10 Gbps data rates with slow varying channel-induced intensity fluctuation when the DD scheme fails to produce the same BER values.

Numerical study of skewness, kurtosis and variance of droplet-size distribution in air-assisted atomizer

We study the approach to calculating the scale and shape parameters of the Weibull droplet-size distribution by means of the skewness, kurtosis and variance, obtained by simulation of atomization in an air-assisted atomizer with different viscosities, densities, flow rates and surface tensions of atomizing liquid. Such approach evades necessity to determine the shift parameter and to use the approximation of distribution obtained from the calculation by the Weibull distribution. The major obstacle to an application of it in processing the data about the atomization of droplets (obtained through the calculation) is the high level of fluctuations of skewness and kurtosis in case of small averaging time.

Geomagnetic pulsations in 1–4 mHz frequency range (Pc5/Pi3) in the magnetotail at different levels of disturbances in the interplanetary medium

In this paper, we study parameters of geomagnetic pulsations in the 1–4 mHz frequency range (Pc5/Pi3) in the magnetotail, utilizing data obtained by Cluster satellites at different levels of fluctuations in the interplanetary magnetic field (IMF) and the solar wind dynamic pressure in 2016. Particular attention is given to the conditions of “zero” disturbance when amplitudes of fluctuations in the interplanetary medium are smaller compared to their typical values. Both under quiet and disturbed conditions, waves of different spatial scales are recorded, with the occurrence rate of large-scale waves increasing under undisturbed conditions. Amplitudes of the large-scale waves occurring in the magnetotail under low intensity of fluctuations outside the magnetosphere are from few tenths to a few nanoteslas (nT), and their power is approximately equal in longitudinal and transverse components. Presumably, these waves are magnetotail eigen-modes.

Геомагнитные пульсации диапазона 1–4 мГц (Pc5/Pi3) в магнитосферном хвосте при разном уровне возмущенности в межпланетной среде

In this paper, we study parameters of geomagnetic pulsations in the 1–4 mHz frequency range (Pc5/Pi3) in the magnetotail, utilizing data obtained by Cluster satellites at different levels of fluctuations in the interplanetary magnetic field (IMF) and the solar wind dynamic pressure in 2016. Particular attention is given to the conditions of “zero” disturbance when amplitudes of fluctuations in the interplanetary medium are smaller compared to their typical values. Both under quiet and disturbed conditions, waves of different spatial scales are recorded, with the occurrence rate of large-scale waves increasing under undisturbed conditions. Amplitudes of the large-scale waves occurring in the magnetotail under low intensity of fluctuations outside the magnetosphere are from few tenths to a few nanoteslas (nT), and their power is approximately equal in longitudinal and transverse components. Presumably, these waves are magnetotail eigen-modes.

Tin-Substituted Chalcopyrite: An n-Type Sulfide with Enhanced Thermoelectric Performance.

The dearth of n-type sulfides with thermoelectric performance comparable to that of their p-type analogues presents a problem in the fabrication of all-sulfide devices. Chalcopyrite (CuFeS2) offers a rare example of an n-type sulfide. Chemical substitution has been used to enhance the thermoelectric performance of chalcopyrite through preparation of Cu1-xSnxFeS2 (0 ≤ x ≤ 0.1). Substitution induces a high level of mass and strain field fluctuation, leading to lattice softening and enhanced point-defect scattering. Together with dislocations and twinning identified by transmission electron microscopy, this provides a mechanism for scattering phonons with a wide range of mean free paths. Substituted materials retain a large density-of-states effective mass and, hence, a high Seebeck coefficient. Combined with a high charge-carrier mobility and, thus, high electrical conductivity, a 3-fold improvement in power factor is achieved. Density functional theory (DFT) calculations reveal that substitution leads to the creation of small polarons, involving localized Fe2+ states, as confirmed by X-ray photoelectron spectroscopy. Small polaron formation limits the increase in carrier concentration to values that are lower than expected on electron-counting grounds. An improved power factor, coupled with substantial reductions (up to 40%) in lattice thermal conductivity, increases the maximum figure-of-merit by 300%, to zT ≈ 0.3 at 673 K for Cu0.96Sn0.04FeS2.

The Effect of Pepper Price Fluctuations on the Expenditures of Farmer Household Consumption in Koronua Village, Sabulakoa District, Konawe Selatan Regency

This research was conducted in Koronua Village, Sabulakoa District, South Konawe Regency from August to September 2021. The purpose of this study was to find out how the fluctuations in pepper prices were and to determine the effect of pepper price fluctuations on the level of family household consumption expenditure in Koronua Village, Sabulakoa District, South Konawe Regency. . The data analysis technique used in this research is descriptive qualitative and quantitative analysis. The results of this study indicate that the level of pepper price fluctuations in Koronua Village has decreased and varied price fluctuations but is within reasonable limits. Meanwhile, pepper price fluctuations have no significant effect on household consumption expenditures for each harvest in Koronua Village, with an average level of expenses. household consumption per month is Rp. 644,853, and the average consumption cost per harvest is Rp. 82,710.52 with a significance value of 0.420, this makes the consumption expenditure variable have no significant effect on price fluctuations because sig 0.420 > 0.05.

Optimal control of transient processes in marine hybrid propulsion systems: Modeling, optimization and performance enhancement

The voice of energy saving and environmental protection is increasing, and the regulations on energy efficiency of ships are becoming stricter. It has forced the shipping industry to accelerate the development of marine hybrid propulsion systems (MHPS). However, the direct control of power distribution optimized by advanced intelligent algorithms may lead to ship oscillations and speed fluctuations. This paper presents a transient process optimization control strategy for solving multi-energy switching. A MHPS simulation model is established from the first nature principle and experimental data. A simulation analysis of the critical parameters affecting the switching process, namely the clutch operating oil pressure and the permanent-magnet synchronous motor (PMSM) output torque. From the viewpoint of restraining speed and oscillation, a process evaluation function is designed to include speed tracking, shock mitigation, and slip work reduction. An upgraded version of WOA, namely Adaptive Perturbation Quantum wave whale optimization algorithm (APQWOA), is proposed to solve the optimal control problem. This transient process optimization control scheme was tested in real time operation through experiments. The results show that the APQWOA is reliably evaluated, which significantly reduces the speed fluctuation and shock level.

Cost Estimation Process of Green Energy Production and Consumption Using Probability Learning Approach

With electric vehicle (EV) charging, green energy production costs could be reduced, and smart grid (SG) reliability improved. Nevertheless, the vast number of EVs could adversely affect the stability of the voltage and cost of operation. The present study designs a new security-based system based on a new EV participation charging method for a decentralized blockchain-enabled SG system. It is aimed at minimizing the level of power alternation in the electrical network and the total charging costs of EVs as mobile systems. In the first step, the power alternation level issue of the SG is formulated based on the capacity of EV batteries, the rate of charging, and EV users’ charging behavior. Next, a new adaptive blockchain-based EV participation (AdBEV) method is proposed, using the Iceberg order execution algorithm for improving EV discharging and charging schedules. Simulated outcomes demonstrate that the suggested method is superior to the genetic algorithm method when it comes to reducing power fluctuation levels and total charging cost.

Impacts of wind field characteristics and non-steady deterministic wind events on time-varying main-bearing loads

Abstract. This work considers the characteristics and drivers of the loads experienced by wind turbine main bearings. Simplified load response models of two different hub and main-bearing configurations are presented, representative of both inverting direct-drive and four-point-mounted geared drivetrains. The influences of deterministic wind field characteristics, such as wind speed, shear, yaw offset, and veer, on the bearing load patterns are then investigated for similarity scaled 5, 7.5, and 10 MW reference wind turbine models. Main-bearing load response in cases of deterministic gusts and extreme changes in wind direction are also considered for the 5 MW model. Perhaps surprisingly, veer is identified as an important driver of main-bearing load fluctuations. Upscaling results indicate that similar behaviour holds as turbines become larger, but with mean loads and load fluctuation levels increasing at least cubically with the turbine rotor radius. Strong links between turbine control and main-bearing load response are also observed.

A feasibility study on nondestructive classification of frozen Atlantic salmon (Salmo salar) fillets based on temperature history at the logistics using NIR spectroscopy.

Temperature fluctuation commonly occurs in the cold chain leading to complete or partial thawing and refreezing of frozen products resulting in a multifrozen product. Such oscillation of temperature could cause significant quality reduction compared to single frozen products. This study was designed to differentiate frozen Atlantic salmon fillets based on the level of temperature fluctuation. Near-infrared spectroscopy (NIRS) coupled with chemometrics was used to classify the frozen fillets stored at no fluctuation (NF), low fluctuation (LF), high fluctuation (HF), and very high fluctuation (VF) temperature. Using spectral profiles obtained at both frozen and thawed states, fillets were classified based on the level of temperature fluctuation by partial least squares discriminant analysis (PLS-DA). The thawed samples showed better classification accuracy (71%) than frozen samples (66%) in a four-class model. Considering the small variation within the first two (NF, LF) and the last two (HF, VF) groups, a two-class classification model was developed using thawed samples, and the obtained model correctly classified the two groups ([NF, LF] and [HF, VF]) with 100 % classification accuracy. Protein- and water-related changes were found important to distinguish the fillets. Based on these findings, the four-class prediction model is found insufficient to be used for nondestructive determination of temperature history of frozen fillets. However, the two-class prediction model with further external validation can be applied to determine the level of temperature fluctuation particularly using fillets scanned at thawed state. PRACTICAL APPLICATION: NIR spectroscopy can be used to evaluate the degree of temperature fluctuation and thus related quality loss throughout the logistics of frozen Atlantic salmon fillets. Researchers, food control authorities, and the retail industry could be the primary beneficiaries of this research output.

Assessment of metal pollution in sediment components of a monsoon-dominated coastal water at Malacca Strait

Fluctuation levels of geochemical elements, sediment texture and nutrients were analysed from five surface sediments taken from the northern Malacca Straits. These samples were obtained during the RV Discovery Scientific cruises in September 2017 and April 2018 to assess pollution sources during monsoon events. The results show a higher output of clay and silt revealing that the monsoonal season and cross-shelf inputs affect textural sediment. On the other hand, fluctuations in geochemical concentrations are due to industrialization and urbanization along the Malacca Straits contributed by the local drainage basin. The presence of the monsoon also affects the diffusivity and absorption at the watersediment interface leading to constant fluctuation along the straits. Principal component analysis of the association between geochemical elements sediment texture and nutrients revealed hydrological factors, mobility and accumulation at the sediment interface.

Relations among Turbulent Fluctuations, Zonal Flows, and Transport Coefficients in Time Series Data of Gyrokinetic Simulations

The relations among turbulent amplitude, zonal-flow amplitude, and transport level are discussed for the time series data of nonlinear gyrokinetic simulations for magnetized toroidal plasmas. Since it was shown that the transport coefficient can be expressed as a function of the time-averaged turbulent fluctuation level and the zonal flow amplitude [M. Nunami et al., Phys. Plasmas 20, 092307 (2013)], we apply the results to a model function for the turbulent plasma transport coefficient to extend to a functional relation which includes not the time-averaged data but the time-series data of gyrokinetic simulations. We obtain a new functional relation to the turbulent fluctuations, the zonal-flow amplitudes, and the transport coefficients as a function of the input parameters of the gyrokinetic simulations such as plasma temperature gradients. It is also confirmed that the obtained functional relation can reduce relative error which is compared with the original function with time-averages.

Pulsatile Trabecular Meshwork Motion: An Indicator of Intraocular Pressure Control in Primary Open-Angle Glaucoma.

(1) Background: To investigate the value of pulsatile trabecular meshwork (TM) motion in predicting the diurnal intraocular pressure (IOP) fluctuation of primary open-angle glaucoma (POAG). (2) Methods: This cross-sectional study recruited 20 normal patients and 30 patients with POAG. Of the POAG group, 20 had stable diurnal IOP and 10 had high IOP fluctuation. A clinical prototype phase-sensitive optical coherence tomography (PhS-OCT) model was used to measure TM pulsatile motion with maximum velocity (MV) and cumulative displacement (CDisp). (3) Results: MV and CDisp were higher in the external region in both normal and POAG patients. All MV and CDisp reduced significantly in the POAG group (p < 0.001). In the POAG group, except MV in the external region (p = 0.085), MV and CDisp in the nasal area were significantly higher than those in the temporal area (p < 0.05). The MV and CDisp in the external region in the nasal area of POAG patients with high IOP fluctuation were much lower than those with stable IOP (pEMV3 = 0.031, pECDisp3 < 0.001); (4) Conclusions: Pulsatile TM motion reduced in POAG patients relevant to the level of diurnal IOP fluctuation. This study presents the segmental variance of TM stiffness in human living eyes and suggests the clinical potential of the measurement of pulsatile TM motion with PhS-OCT for the evaluation of diurnal IOP fluctuation.

Optimum storage sizing in a hybrid wind-battery energy system considering power fluctuation characteristics

Power dispatching is one of the important requirements for wind power systems. Using energy storage systems, especially the battery energy storage system (BESS) is one of the more effective solutions for overcoming this problem. The required battery capacity depends on the fluctuation level of the output power, which is affected by several factors. In this paper, the object is to estimate the required battery capacity based on wind speed data and turbines position in the design phase of a wind farm. An analytical method is presented to estimate the short-term fluctuation of wind farm power considering wake effect, turbulence, and spatial smoothing. Then, a method for estimating the optimum battery capacity, based on the statistical characteristics of wind farm power including average value and standard deviation over a long-term period, is presented. In addition, a new model is presented to estimate the battery lifetime in the case of non-uniform charge/discharge cycles. The numerical results for a case study, over one-year wind speed data, are presented and the results show the effectiveness of the proposed approach in determining the optimum battery capacity.

Edge turbulence measurements in L-mode and I-mode at ASDEX Upgrade

The I-mode confinement regime is promising for future reactor operation due to high energy confinement without high particle confinement. However, the role of edge turbulence in creating I-mode's beneficial transport properties is still unknown. New measurements of edge turbulence (ρpol=0.9−1.0) in L-modes and I-modes at low and high densities at ASDEX Upgrade are presented in this paper. A high radial resolution correlation electron cyclotron emission radiometer measures the broadband turbulence throughout the L-mode and I-mode edge and pedestal. The weakly coherent mode (WCM) is measured in both L-mode and I-mode near the last closed flux surface with Te fluctuation levels of 2.3%–4.2%, with a frequency shift between the two phases related to a deeper Er well in I-mode. An neTe phase diagnostic captures a change of the WCM neTe phase between L-mode and I-mode from −171° to −143°. The thermal He beam diagnostic measures a WCM wavenumber range of −0.5 to −1.0 cm−1. A low-frequency edge oscillation (LFEO) appears in the I-mode phase of these discharges and displays coupling to the WCM, but the LFEO does not appear in the L-mode phase. Linear gyrokinetic simulations of the outer core and pedestal top turbulence indicate that while the dominant turbulent modes in the outer core are ion directed and electrostatic, the turbulence becomes increasingly electron directed and electromagnetic with increasing radius. Collisionality is not found to impact characteristics of the L-mode and I-mode edge turbulence with respect to the presence of the WCM; however, the quality of global confinement decreases with collisionality.

Kinetic modeling of neutral transport for a continuum gyrokinetic code

We present the first-of-its-kind coupling of a continuum full-f gyrokinetic turbulence model with a 6D continuum model for kinetic neutrals, carried out using the Gkeyll code. Our objective is to improve the first-principle understanding of the role of neutrals in plasma fueling, detachment, and their interaction with edge plasma profiles and turbulence statistics. Our model includes only atomic hydrogen and incorporates electron-impact ionization, charge exchange, and wall recycling. These features have been successfully verified with analytical predictions and benchmarked with the DEGAS2 Monte Carlo neutral code. We carry out simulations for a scrape-off layer (SOL) with simplified geometry and National Spherical Torus Experiment parameters. We compare these results to a baseline simulation without neutrals and find that neutral interactions reduce the normalized density fluctuation levels and associated skewness and kurtosis, while increasing auto-correlation times. A flatter density profile is also observed, similar to the SOL density shoulder formation in experimental scenarios with high fueling.

Capacitive Humidity Sensors Based on Nanocellulose for Biodegradable Electronics

The humidity sensor is an important device used in many areas of human life, such as agriculture, medicine, industry, meteorology and more. Most often, synthetic polymers are used for the manufacture of humidity sensors, which after the end of their operation are accumulated in the form of electronic waste, polluting the environment. Currently, biodegradable polymers are in great demand. Such materials include nanocellulose, which can be made from both wood and plant raw materials. It has already been proven that nanocellulose is a promising material for use in humidity-sensitive devices. However, it was not clear the effect of sensitive film’s thickness on the characteristics of humidity sensors. In this work, capacitive humidity sensors based on nanocellulose were fabricated. Nanocellulose (NC) was obtained from reeds by the TEMPO method. The moisture-sensitive layer of NC was applied by dripping. Static (sensitivity, response, hysteresis) and dynamic (response time, recovery time, short- and long-term stability) characteristics of the manufactured humidity sensors were measured in dependence on mass of NC film (from 0.3 to 3.6 mg) and test signal frequency (100 Hz and 1000 Hz). The response of the sensors was increased with the weight of moisture-sensitive NC film and reached 1412 nF at 100 Hz (783 nF at 1000 Hz) for the sample of 0.6 mg NC, and then decreased with further increase in mass. The sensitivity of the sensors varied similarly, but the maximum value was observed for the sample with a mass of 1.8 mg and was 0.161 (%RH)-1 for 100 Hz (0.165 (%RH)-1 for 1000 Hz). The shortest response time had the sample with the lowest mass of moisture-sensitive film (100 s). With a further increase in the mass of moisture-sensitive NC film, the response and recovery time increased monotonically. Also, the sample with the lowest mass of the moisture-sensitive layer shows the lowest value of hysteresis (0.1%) and also increased with the increasing mass of the moisture-sensitive layer. In the study of short-term stability, samples weighing from 0.3 to 0.6 mg showed a significantly higher level of fluctuations (10 - 20%) compared to samples with a weight of the moisture-sensitive layer of 1.8 - 3.6 mg (1 - 4%). So, you should use nanocellulose film of larger mass (1.8… 3.6 mg) in order to improve the sensitivity and short-term stability of the devices. In view of the responce and recovery time as well as repeatability of the sensor characteristics, thin nanocellulose films (0.3… 0.5 mg) should be used. The direction of further research is to improve the long-term stability of the devices, in particular by modifying the nanocellulose film with adding certain impurities.

Microfluidic platform for studying the anti‐cancer effect of ursolic acid on tumor spheroid

At present, the probability that a new anti-tumor drug will eventually succeed in clinical trials is extremely low. In order to make up for this shortcoming, the use of a three-dimensional (3D) cell culture model for secondary screening is often necessary. Cell spheroid is the easiest 3D model tool for drug screening. In this study, the microfluidic chip with a microwell array was manufactured, which could allow the formation of tumor spheroids with uniform size and easily retrieve cell spheroids from the chip. Cell spheroids were successfully cultured for over 15 days and the survival rate was as high as 80%. Subsequently, cellular response to the ursolic acid (UA) was observed on the chip. Compared to the monolayer culture cells in vitro, the tumor spheroids showed minor levels of epithelial-mesenchymal transition fluctuation after drug treatment. The mechanism of cell spheroid resistance to UA was further verified by detecting the expression level of upstream pathway proteins. But the invasive ability of tumor spheroids was attenuated when the duration of action of UA extended. The anti-cancer effect of UA was innovatively evaluated on breast cancer by using the microfluidic device, which could provide a basis and direction for future preclinical research on UA.

Analisis Yuridis Cryptocurrrency Dalam Prespektif Hukum Surat Berharga Di Indonesia

Abstract— Cryptocurrency as a digital product has grown significantly. Cryptocurrency as a digital currency has been accepted by the world community, with different implementations in each country. Indonesian law regulates cryptocurrency as a commodity product that can be traded on the Futures Exchange. As a commodity, cryptocurrency monitoring is carried out by BAPPEBTI (Commodity Futures Trading Supervisory Agency). The position of cryptocurrency as a commodity is unfortunate by some, who expect cryptocurrencies to be recognized as legal tender as is the case in some countries. Securities law regulates the elements that must be met in order for an object to be recognized as a means of payment. This is also supported by current practices, namely the level of significant fluctuations in cryptocurrencies and the absence of government intervention which makes the government unable to carry out its role as controller. This study aims to determine the position of cryptocurrency in the perspective of Indonesian law. This study uses a type of normative juridical research with a statutory approach and a conceptual approach. The results of the study note that until now cryptocurrency cannot be recognized as a means of payment and is recognized as a commodity. Keywords: cryptocurrencies, securities law, means of payment