Three-parameter Model Research Articles

Machine condition change detection based on data segmentation using a three-regime, [formula omitted]-stable Hidden Markov Model

An adaptation of HMM for signal segmentation is proposed. It is developed for Health Index (HI) data, which behave in different ways depending on machine condition. HI can be constant, then linearly or exponentially increasing. Knowledge of the current regime is critical for the early stage, as well as developed fault detection and RUL prognosis. The analysed data have time-varying variance/scale and noise changes from Gaussian to non-Gaussian. We initially propose an HMM with α-stable distribution and a three-parameter model. We analyse three versions of HMM: for untransformed data (model ‘G’), for detrended data (‘D’) and additionally rescaled data (‘DN’). We show that model ’D’ is sufficient to find the first change point (detection of early stage damage), while model ’G’ is the most effective for the identification of the second change point. The proposed and verified approach allows us to effectively find the borders between the segments.

Three-dimensional magnetic resonance elastography combining proton-density fat fraction precisely identifies metabolic dysfunction-associated steatohepatitis with significant fibrosis

PurposePatients with metabolic dysfunction-associated steatohepatitis (MASH) and significant fibrosis (fibrosis stage≥2), known as Fibro-MASH, are at increased risk of liver-related outcomes and lower rates of spontaneous disease regression. The aim was to investigate three-dimensional MR elastography (3D-MRE) combining proton-density fat fraction (PDFF) as a means of identifying Fibro-MASH. MethodsForty-eight New Zealand rabbits were fed a high-fat/cholesterol or standard diet to obtain different disease activity and fibrosis stages. Shear stiffness (SS) and Damping Ratio (DR) were derived from 3D-MRE, whereas PDFF was from a volumetric 3D imaging sequence. Steatosis grade, metabolic dysfunction-associated steatotic liver disease activity score (MAS), and fibrosis stage were diagnosed histologically. Serum markers of fibrosis and inflammation were also measured. Correlation and comparison analysis, Receiver operating characteristic curves (ROC), Delong test, logistic regression analysis, and Net reclassification improvement (NRI) were performed. ResultsPDFF correlated with steatosis grade (rho = 0.853). SS increased with developed liver fibrosis (rho = 0.837). DR correlated with MAS grade (rho = 0.678). The areas under the ROC (AUROCs) of SS for fibrosis grading were 0.961 and 0.953 for ≥F2, and ≥ F3, respectively. All the biochemical parameters were considered but excluded from the logistic regression analysis to identify Fibro-MASH. FF, SS, and DR were finally included in the further analysis. The three-parameter model combining PDFF, SS, and DR showed significant improvement in NRI over the model combining SS and PDFF (AUROC 0.973 vs. 0.906, P = 0.081; NRI 0.28, P < 0.05). Conclusion3D-MRE combining PDFF may characterize the state of fat content, disease activity and fibrosis, thus precisely identify Fibro-MASH.

Experimental Study of Influence of Freeze–Thaw Cycles on the Dynamic Properties of Weathered Sand-Amended Expansive Soils

Expanded soils are widely distributed in Xinjiang, China, so roadbeds will inevitably pass through the areas of the expansive soil during road construction. While Xinjiang belongs to the seasonal frozen region, subjected to a freeze–thaw cycle, mud pumping is likely to occur in the subgrade under dynamical load. To study the dynamic properties of expansive soil for a range of freezing–thawing cycles and weathered sand contents, a series of dynamic triaxial tests were performed using a medium-scale true triaxial apparatus equipped with the cyclic loading device. And the maximum dynamic elastic modulus (Edmax) and ultimate dynamic stress amplitude (σdmax) were quantitatively analyzed by the modified Hardin–Drnevich three-parameter model, on which the expression of the damage degree under the joint action of both was established. The results indicate that the dynamic performance of expansive soil is greatly affected by freezing–thawing. Under the same weathered sand content, the maximum dynamic elastic modulus and the maximum dynamic stress amplitude of soil are inversely related to the number of freezing–thawing cycles. And, those two parameters tend to be stable after the sixth freeze–thaw cycle. Under the same number of freeze–thaw cycles, the maximum dynamic elastic modulus and the maximum dynamic stress amplitude firstly decrease and then increase with the increase in the weathered sand content. The critical dosage of weathered sand is 10%, and the strength of the improved soil reached the minimum value under this context. The damage degree model that integrates the effects of freeze–thaw cycles and the weathered sand can better predict the damage degree of soil.

Role of Simple Spatial Gradient in Reinforcing the Accuracy of Temperature Determination of HED Plasma via Spectral Line-Area Ratios

We report on the simulation of temperature gradients in tamped NaFMgO target-foil plasma, heated and backlit by z-pinch dynamic hohlraum radiation. Our approach compares the spectroscopic output of a collisional-radiative model (prismspect) with soft X-ray absorption spectra collected on Sandia National Laboratories’ (SNL) Z Pulsed Power Facility. The pattern of minimum χ2 is seen to agree with an efficient, three-parameter model. Results show that a negligible gradient in electron temperature Te is consistent with experimental data, justifying the assumptions of previous work. The predicted sensitivity of line spectra to the gradient-aligned profile of Te is documented for each spectral feature, so that the line-area ratio between a pair of spectral features may be assessed as a proxy for the existence and quantification of such gradients.

Experimental study on dynamic resilient modulus of subgrade with circulating fluidized bed combustion ash as filler

Using circulating fluidized bed combustion ash (CFBCA) as roadbed filler can solve the problem of secondary utilization, and dynamic resilient modulus (DRM) can match the dynamic performance of roadbed filler under driving load. In order to explore the dynamic performance of the subgrade with CFBCA as filler under driving load, based on the dynamic triaxial test and mercury intrusion porosimetry test, the DRM of the sample under different curing ages, compaction, moisture content, stress, dry-wet and freeze–thaw cycle conditions were studied, and the pore distribution characteristics of the sample were analyzed. The results show that the DRM of CFBCA samples increases significantly in the 0 ∼ 7d age curing period, and increases slowly in 7 ∼ 28d; with the increase of f-CaO and SO3 content, the DRM of CFBCA samples increased; after the dry-wet cycle and freeze–thaw cycle, the DRM of the CFBCA sample decreased, and the decrease was more obvious under the dry-wet cycle. With the increase of f-CaO and SO3 content, the total porosity and macropore of CFBCA samples decreased; with the decrease of moisture content, the total porosity and macropore of CFBCA samples increased, the DRM becomes smaller. Under different moisture content and compaction, the DRM fitting of the CFBCA sample shows that the prediction results of the three-parameter theoretical model with volume stress and octahedral shear stress as variables are compared with the test results with a high correlation (R2 > 0.96), it can effectively predict the DRM of the subgrade with CFBCA used as filler.

DeepFittingNet: A deep neural network-based approach for simplifying cardiac T1 and T2 estimation with improved robustness.

To develop and evaluate a deep neural network (DeepFittingNet) for T1 /T2 estimation of the most commonly used cardiovascular MR mapping sequences to simplify data processing and improve robustness. DeepFittingNet is a 1D neural network composed of a recurrent neural network (RNN) and a fully connected (FCNN) neural network, in which RNN adapts to the different number of input signals from various sequences and FCNN subsequently predicts A, B, and Tx of a three-parameter model. DeepFittingNet was trained using Bloch-equation simulations of MOLLI and saturation-recovery single-shot acquisition (SASHA) T1 mapping sequences, and T2 -prepared balanced SSFP (T2 -prep bSSFP) T2 mapping sequence, with reference values from the curve-fitting method. Several imaging confounders were simulated to improve robustness. The trained DeepFittingNet was tested using phantom and in-vivo signals, and compared to the curve-fitting algorithm. In testing, DeepFittingNet performed T1 /T2 estimation of four sequences with improved robustness in inversion-recovery T1 estimation. The mean bias in phantom T1 and T2 between the curve-fitting and DeepFittingNet was smaller than 30 and 1 ms, respectively. Excellent agreements between both methods was found in the left ventricle and septum T1 /T2 with a mean bias <6 ms. There was no significant difference in the SD of both the left ventricle and septum T1 /T2 between the two methods. DeepFittingNet trained with simulations of MOLLI, SASHA, and T2 -prep bSSFP performed T1 /T2 estimation tasks for all these most used sequences. Compared with the curve-fitting algorithm, DeepFittingNet improved the robustness for inversion-recovery T1 estimation and had comparable performance in terms of accuracy and precision.

Investigating the effect of different parameters on the rheological behavior of hybrid nano-lubricant containing MWCNT and CuO nanoparticles using response surface methodology (RSM)

In this study, changes in the viscosity of MWCNT-CuO (40%-60%)/ 10 W40 hybrid nano-lubricant (HNL) were modeled and evaluated with the influence of independent parameters using response surface methodology (RSM). RSM with statistical mathematical techniques and appropriate modeling is one of the best methods for evaluating changes in viscosity in terms of independent parameters. Independent and effective parameters on viscosity include temperature (T), solid volume fraction (SVF) and shear rate (SR). Viscosity changes were investigated by presenting different models using 174 laboratory data and the best model among the different models with three parameters T, SR and SVF was introduced. The accuracy of the models was checked with R2, Adjusted R2, and Predicted R2 parameter values. The three-parameter model with parameter values R2 = 0.9992 Adjusted R2 = 0.9990 and Predicted R2 = 0.9986 has higher accuracy than other models. Using the optimal model, the process of viscosity changes was analyzed and investigated, and after evaluating the independent parameters, it was found that the effect of T on viscosity is greater than other parameters. The SR parameter has the least effect on viscosity changes. Also, the normal scatter diagram for the Quartic model for viscosity in terms of T, SVF and SR parameters is close to the bisector line and does not need a transfer function. The graph of the residual values according to the predicted values is in the range between + 3.7 and −3.7. Tthis shows that the accuracy of the selected model is satisfactory.

A New Extension of the Inverse Paralogistic Distribution using Gamma Generator with Application

This study proposed a three-parameter model called the gamma inverse paralogistic (GiPL) distribution model. The probability density and cumulative distribution functions were presented together with the quantile function. Properties such as measures of reliability, the kth raw moment and moment-generating function, partial moments, order statistics, log-likelihood functions for maximum likelihood estimations, Renyi entropy and the ordering of random variables were provided. To test the performance of the parameters, a simulation study was conducted. The simulation result was assessed using the mean, bias and root mean square errors. Finally, the data set on the number of COVID-19-infected individuals per age was used to apply the model and compared with various recently developed distribution models. Results showed the superiority of the GiPL distribution model over these models.

On the stress dependency of sand production coefficient in hydro-dynamical sanding criteria

Solids production is a complex physical process which is controlled by several factors including mechanical failure from in-situ stresses and hydrodynamic erosion from fluid flow. Hydrodynamic models for the prediction of sand production involve sanding criteria based on filtration theories. Such models contain a constitutive model parameter, the coefficient λ, with dimensions of inverse length which is calibrated by sand erosion tests, but its nature and its dependencies have not been clarified to date. The aim of this work is an attempt to refine the hydrodynamic models by investigating the dependence of the sand production coefficient λ on the external stress conditions and on the plastic zone Λ that is developed on hollow cylinders tests and propose an expression describing its importance in the sand production prediction modelling. The aim of the work is obtained through simulations with finite elements by utilizing the well-established Arbitrary Lagrangian-Eulerian (ALE) analysis considering the poro-mechanical coupling of the fluid-solid system for simulating hollow cylinder tests. Best fitting experimental data estimated values for the sand production coefficient for various values of external stress are obtained through back analysis. The dependence of λ on the external stress turns out to be fairly smooth and a three-parameter model is proposed to describe that dependence: a scale parameter, an exponent, and a stress parameter defining the magnitude of stress at which erosion onset is predicted. It turns out that the stress parameter is associated with the minimum stress required for plastic yielding to occur, which was also estimated theoretically. This finding is in agreement with the physical assumption underlying the simulations that erosion onsets and progresses after the material reaches a critical plastic strain as a consequence of material plastic yielding. A power law model describing the dependence of λ on the plastic zone depth is also proposed and discussed.

The use of measurement frameworks to explore the qualities of test items

&lt;span lang="EN-US"&gt;Psychometricians and researchers have grown increasingly concern about students’ performance. It is noteworthy from observation in the selected university of education in Nigeria that many of these students do not attend lectures for general courses particularly EDU 222 (tests and measurement) due to overcrowded lecture halls, the classroom climate factor, and other latent factors, such as exam conditions, test anxiety among others. Consequently therefore, students’ performance in EDU 222 does not significantly correlate with these challenges. The characteristics of the item parameter of the Tests and Measurement achievement test at the selected University of Education in Ogun State, Nigeria, were therefore examined in this study using measurement theories. The study employed an ex-post facto research of non-experimental design. Purposive sampling was used to select 6,203 second-year undergraduates offering EDU 222 for the 2018/2019 academic year. To analysis students’ responses to 30 multiple-choice questions on tests and measurement, factor analysis, item calibration, an independent sample t-test with a significance threshold of 0.05 were utilized with empirical reliability of 0.64. The results showed the test items satisfied the three-parameter logistics model and uni-dimensionality assumption. The findings also showed that the item response theory (IRT) eliminated 7 items due to guessing, while the classical test theory (CTT) eliminated 13 items. The test is prone to guessing, thus, helps pupils do better on the exam. To establish parameter estimates during test development, higher education institutions (HEIs) should employ the use of IRT.&lt;/span&gt;

MODELING OF THE WATER ADSORPTION ISOTHERM OF MANGO SLICES (MANGIFERA INDICA L.) DRIED UNDER HOT AIR

The general objective of this work is to contribute to the reduction of post-harvest losses of mangoes by the transformation into stable dried products.This research aims to determine the best storage conditions for dried mangoes.Thus, the water adsorption isotherms of mango slices dried under hot air were experimentally determined by the static thermogravimetric method at 25°C.Eight mathematical models from the literature were used (GAB, BET, Hasley, Henderson, Harking and Dura, Oswin, Chung and Pfost, Smith) to describe the hygroscopic behavior of dried mango slices.Regression analysis was performed using MatLab R2016a software to determine the coefficients, model parameters and statistical parameters of the smoothing.The results revealed that the equilibrium is obtained from 35 days for the two samples and the adsorption isotherms determined are of type II characterized by a sigmoidal shape.In addition, the three-parameter (GAB) model showed good agreement with the experimental data (r= 0.999 and 0.997 respectively for slices with thicknesses of 1cm and 1.5cm) at 25°C.The water content of the mono-molecular layer is 2.295% at 25°C for the 1cm slices and 2.289% at 25°C for the 1.5cm slices.The net isosteric heat of adsorption tends towards zero for high water contents (0.052KJ/mol at 44.472% water).The linearity between enthalpy (net isosteric heat) and differential entropy of adsorption shows their compensation.

Kinetics and Mechanism of Camptothecin Release from Transferrin-Gated Mesoporous Silica Nanoparticles through a pH-Responsive Surface Linker.

Stimuli-responsive nanomaterials have emerged as a promising strategy for inclusion in anticancer therapy. In particular, pH-responsive silica nanocarriers have been studied to provide controlled drug delivery in acidic tumor microenvironments. However, the intracellular microenvironment that the nanosystem must face has an impact on the anticancer effect; therefore, the design of the nanocarrier and the mechanisms that govern drug release play a crucial role in optimizing efficacy. Here, we synthesized and characterized mesoporous silica nanoparticles with transferrin conjugated on their surface via a pH-sensitive imine bond (MSN-Tf) to assess camptothecin (CPT) loading and release. The results showed that CPT-loaded MSN-Tf (MSN-Tf@CPT) had a size of ca. 90 nm, a zeta potential of -18.9 mV, and a loaded content of 13.4%. The release kinetic data best fit a first-order model, and the predominant mechanism was Fickian diffusion. Additionally, a three-parameter model demonstrated the drug-matrix interaction and impact of transferrin in controlling the release of CPT from the nanocarrier. Taken together, these results provide new insights into the behavior of a hydrophobic drug released from a pH-sensitive nanosystem.

Full Regional Creep Displacement Map of Articular Cartilage Based on Nanoindentation Array.

The elucidation of the mechanisms underlying articular cartilage lesions poses a formidable challenge in the field of cartilage repair. Despite significant strides in cartilage mechanics research, the region-dependent creep properties of articular cartilage remain elusive. In this study, we employ depth-sensing indentation tests to experimentally determine the creep properties of four distinct regions of articular cartilage, thereby unveiling a region-dependent full map of creep parameters. The measured creep displacement-time response curves indicate that the creep properties of the articular cartilage exhibit a clear regional correlation. Accordingly, the full regional creep map of articular cartilage is experimentally constructed for the first time. The correlation between the microstructures and the creep properties of cartilage in different regions is revealed. A three-parameter model is established to describe the creep velocity-displacement response of cartilage. Raman spectra reveal that the proteoglycan content is positively correlated with creep properties. The Raman shift directly indicates diverse residual stresses in different microregions. The obtained data facilitate a deep understanding of the potential creep dependent damage mechanism of cartilage and the further development of artificial cartilage materials.

Study on Modelling Method of Resilient Mat Used under Floating Slab Track.

Kelvin's model is widely used to simulate the dynamic characteristic of a resilient mat under a slab track. To develop an effective calculation model for a resilient mat using a solid element, a three-parameter viscoelasticity model (3PVM) was employed. With the help of the user-defined material mechanical behavior, the proposed model was implemented in software ABAQUS. To validate the model, a laboratory test was performed on a slab track with a resilient mat. Then, a finite element model of the track-tunnel-soil system was built. The calculation results using the 3PVM was compared with those using Kelvin's model and the test results. The results indicate that the 3PVM can better reflect the dynamic characteristics of resilient mat than Kelvin's model, especially over 10 Hz. Compared with the test results, the 3PVM has an average error of 2.7 dB and a max error of 7.9 dB at 5 Hz.

Precision calculations of Bd,s → π, K decay form factors in soft-collinear effective theory

We improve QCD calculations of the semileptonic Bd,s→ π, K decay form factors at large hadronic recoil by implementing the next-to-leading-logarithmic resummation for the obtained leading-power light-cone sum rules in the soft-collinear effective theory (SCET) framework and by computing for the first time the non-vanishing spectator-quark mass correction dictating the SU(3)-flavour symmetry breaking effects between these fundamental quantities at the one-loop accuracy. Additionally, we endeavour to investigate a variety of the subleading-power contributions to these heavy-to-light form factors at mathcal{O}left({alpha}_s^0right) with the same methodology, by including the higher-order terms in the heavy-quark expansion of the hard-collinear quark propagator, by evaluating the desired effective matrix element of the next-to-leading-order term in the SCETI representation of the weak transition current, by taking into account the off-light-cone contributions of the two-body heavy-quark effective theory (HQET) matrix elements as well as the three-particle higher-twist corrections from the subleading bottom-meson light-cone distribution amplitudes (LCDAs), and by computing the twist-five and twist-six four-body higher-twist effects with the aid of the factorization approximation. Having at our disposal the SCET sum rules for the exclusive B-meson decay form factors under discussion, we further explore in detail numerical implications of the newly computed subleading-power corrections by employing the three-parameter model for both the leading-twist and higher-twist B-meson distribution amplitudes. Taking advantage of the customary Bourrely-Caprini-Lellouch (BCL) parametrization for the complete set of the semileptonic Bd,s→ π, K form factors, we then determine the correlated numerical results for the interesting series coefficients, by carrying out the simultaneous fit of the exclusive B-meson decay form factors to both the achieved SCET sum rule predictions at small momentum transfer (q2) and the available lattice QCD results at large momentum transfer. Subsequently, we perform a comprehensive phenomenological analysis of the full angular observables, the lepton-flavour university ratios and the lepton polarization asymmetries for the flavour-changing charged- current Bto pi ell {overline{nu}}_{ell } and {B}_sto Kell {overline{nu}}_{ell } decays (with ℓ = μ, τ) together with the differential q2-distribution for the exclusive rare Bto K{nu}_{ell }{overline{nu}}_{ell } decays in the Standard Model.

Sensitivity Analysis of the Main Structural Parameters of the Four-Tower Partially Cable-Stayed Bridge

We established a structural finite element model based on a four-tower partially cable-stayed bridge. We performed a study to determine the appropriate settings of several main parameters of the four-tower partially cable-stayed bridge. Given changes in the stiffness of the main girder, stayed cable and length of cable-free zones in the span, a three-parameter coupling coordination model was constructed. The coupling degree and coordination degree between different parameters are calculated and compared, the primary and secondary parameters affecting the structural performance of some cable-stayed bridges are determined, and a more suitable parameter composition interval is proposed. The sensitivity analysis of the main structural parameters of the four-tower partial cable-stayed bridge has not been published in the literature, and there is no coupling study on the length of the cable-free zone and the stiffness of the main girder and stay cable. The overall structural stiffness was improved by increasing the main girder’s stiffness and stayed cable, with the main girder stiffness being the primary parameter. The increase in uncoupled zone length in the span improved the utilization rate of the line within a specific range; however, too long a length led to a reduction in overall structural stiffness. The main girder stiffness was set between EG′IG/EGIG = 1~3, while stayed cable stiffness was set between ECAC′/ECAC = 0.8~1.4. The length of the cable-free zone in the span was set between l1/l0 = 0.08~0.15, while the coupling coordination degree was medium to high coordination. The structural performance of the background engineering bridge was improved. However, the conclusion of this paper is more applicable to low-pylon cable-stayed bridges, and it has not been verified whether it applies to traditional cable-stayed bridges.

Critical Review and Discussion of the Nonlinear Form of Radke–Prausnitz Model in Adsorption Solid–Liquid Phases

The Radke–Prausnitz model, a typical three-parameter model belonging to the Langmuir–Freundlich-type equation, is increasingly being used to correlate the equilibrium data of various adsorption processes. However, very few published works provide the correct information on (1) the nonlinear form of this model, (2) the units of its parameters, and (3) its original citation. This work provides a critical analysis of the Radke–Prausnitz model with special emphasis on promoting its proper application in adsorption research. The correct expression and citation of the models used in adsorption studies are provided. The correct units of its parameters aRP, bRP, and β are L/kg, (mol/kg)/(mol/L)β, and unitless when the solution phase concentration Ce is given in mol/L and the adsorbed phase concentration qe is defined in mol/kg. The Radke–Prausnitz model can be reduced to the Henry, Freundlich, Langmuir, or Redlich–Peterson model in some special cases. The Radke—Prausnitz model is valid when the exponent β is in the range of 0≤β≤1. A new adsorption equilibrium constant of this model is introduced. The feasibility of using the new equilibrium constant to calculate the thermodynamic parameters (ΔG°, ΔH°, and ΔS°) of adsorption processes is discussed herein.

Statistical Inference of the Half Logistic Modified Kies Exponential Model with Modeling to Engineering Data

The half-logistic modified Kies exponential (HLMKEx) distribution is a novel three-parameter model that is introduced in the current work to expand the modified Kies exponential distribution and improve its flexibility in modeling real-world data. Due to its versatility, the density function of the HLMKEx distribution offers symmetrical, asymmetrical, unimodal, and reversed-J-shaped, as well as increasing, reversed-J shaped, and upside-down hazard rate forms. An infinite linear representation can be used to represent the HLMKEx density. The HLMKEx model’s fundamental mathematical features are obtained, such as the quantile function, moments, incomplete moments, and moments of residuals. Additionally, some measures of uncertainty as well as stochastic ordering are derived. To estimate its parameters, eight estimation methods are used. With the use of detailed simulation data, we compare the performance of each estimating technique and obtain partial and total ranks for the accuracy measures of absolute bias, mean squared error, and mean absolute relative error. The simulation results demonstrate that, in contrast to other competing distributions, the proposed distribution can actually fit the data more accurately. Two actual data sets are investigated in the field of engineering to demonstrate the adaptability and application of the suggested distribution. The findings demonstrate that, in contrast to other competing distributions, the provided distribution can actually fit the data more accurately.

Quantification of cross-relaxation in downfield 1 H MRS at7T in human calf muscle.

The purpose of this study was to characterize the 1 H downfield MR spectrum from 8.0 to 10.0ppm of human skeletal muscle at 7T and determine the T1 and cross-relaxation rates of observed resonances. We performed downfield MRS in the calf muscle of 7 healthy volunteers. Single-voxel downfield MRS was collected using alternately selective or broadband inversion-recovery sequences and spectrally selective 90° E-BURP RF pulse excitation centered at 9.0ppm with bandwidth = 600 Hz (2.0ppm). MRS was collected using TIs of 50-2500 ms. We modeled recovery of the longitudinal magnetization of three observable resonances using two models: (1) a three-parameter model accounting for the apparent T1 recovery and (2) a Solomon model explicitly including cross-relaxation effects. Three resonances were observed in human calf muscle at 7T at 8.0, 8.2, and 8.5ppm. We found broadband (broad) and selective (sel) inversion recovery T1 = mean ± SD (ms): T1-broad,8.0ppm = 2108.2 ± 664.5, T1-sel,8.0ppm = 753.6 ± 141.0 (p = 0.003); T1-broad,8.2ppm = 2033.5 ± 338.4, T1-sel,8.2ppm = 135.3 ± 35.3 (p < 0.0001); and T1-broad,8.5ppm = 1395.4 ± 75.4, T1-sel,8.5ppm = 107.1 ± 40.0 (p < 0.0001). Using the Solomon model, we found T1 = mean ± SD (ms): T1-8.0ppm = 1595.6 ± 491.1, T1-8.2ppm = 1737.2 ± 963.7, and T1-8.5ppm = 849.8 ± 282.0 (p =0.04). Post hoc tests corrected for multiple comparisons showed no significant difference in T1 between peaks. The cross-relaxation rate σAB = mean ± SD (Hz) of each peak was σAB,8.0ppm = 0.76 ± 0.20, σAB,8.2ppm = 5.31 ± 2.27, and σAB,8.5ppm = 7.90 ± 2.74 (p < 0.0001); post hoc t-tests revealed the cross-relaxation rate of the 8.0ppm peak was significantly slower than the peaks at 8.2 ppm (p =0.0018) and 8.5ppm (p =0.0005). We found significant differences in effective T1 and cross-relaxation rates of 1 H resonances between 8.0 and 8.5ppm in the healthy human calf muscle at 7T.

A new three-dimensional entrainment model for wind-turbine wakes

A linear entrainment (LE) wake model can maintain both mass conservation and momentum conservation, improving wake prediction accuracy. However, its key parameter entrainment coefficient E determines the exchange of fluids inside and outside the wake region, which significantly affects its prediction accuracy and requires further testing and correction. Also, its assumed top-hat shape can cause large errors. This work first establishes the best value of E (E = 0.12) based on experimental data and numerical simulation. Then we construct the three-dimensional cosine-shaped wake model by correcting the radial velocity distribution of the LE model with the cosine function and considering the wind shear effect. In addition, different from the two-parameter turbulence intensity model used in the previous models, the recently proposed three-parameter turbulence-intensity model is used to correct the E value in order to integrate the effects on downstream distance, thrust coefficient, and ambient turbulence intensity. Comparisons with two field measurements and three wind tunnel test cases demonstrate the accuracy of this model, which provides predictions of wake velocity loss in both the lateral and vertical directions that are more accurate than those of the conventional models.