MHz cut-off frequency and permeability mechanism of iron-based soft magnetic composites

The lack of soft magnetic composites with high power density in MHz frequency range has become an obstacle in the efficient operation of the electrical and electronic equipments.Here,a promising method to increase the cut-off frequency of iron-based soft magnetic composites to hundreds of MHz is reported.The cut-off frequency is increased from 10 MHz to 1 GHz by modulating the height of the ring,the distribution of particles,and the particle size.The mechanism of cut-off frequency and permeability is the coherent rotation of domain modulated by inhomogeneous field due to the eddy current effect.An empirical formula for the cut-off frequency in a magnetic ring composed of iron-based particles is established from experimental data.This work provides an effective approach to fabricate soft magnetic composites with a cut-off frequency in hundreds of MHz.

Cut-off value of glycated hemoglobin A1c for detecting diabetic retinopathy in the Chinese population

BACKGROUND Glycated hemoglobin A1c(HbA1c)is considered the most suitable for diabetes mellitus diagnosis due to its accuracy and convenience.However,the effect of HbA1c on diabetic retinopathy(DR)in the Han and Korean populations in Jilin,China,remains inconclusive.AIM To determine the best cut-off of HbA1c for diagnosing DR among the Chinese.METHODS This cross-sectional study included 1933 participants from the Yanbian area of Jilin Province,China.Trained investigators employed a questionnaire-based survey,physical examination,laboratory tests,and fundus photography for the investigation.The best cut-off value for HbA1c was established via the receiver operating characteristic curve.The factors associated with HbA1c-associated risk factors were determined via linear regression.RESULTS The analysis included 887 eligible Chinese Han and Korean participants,591 of whom were assigned randomly to the training set and 296 to the validation set.The prevalence of DR was 3.27% in the total population.HbA1c of 6.2% was the best cut-off value in the training set,while it was 5.9% in the validation set.In both Chinese Han and Korean populations,an HbA1c level of 6.2% was the best cut-off value.The optimal cut-off values of fasting blood glucose(FBG)≥7 mmol/L and<7 mmol/L were 8.1% and 6.2% respectively in Han populations,while those in Korean populations were 6.9%and 5.3%,respectively.Age,body mass index,and FBG were determined as the risk factors impacting HbA1c levels.CONCLUSION HbA1c may serve as a useful diagnostic indicator for DR.An HbA1c level of 6.2% may be an appropriate cut-off value for DR detection in the Chinese population.

Numerical Investigation of Flutter Stability in Subsonic Space Turbine Blisk with Emphasis on Cut-on/Cut-off Modes and Interblade Phase Angles

The so-called blisks,i.e.integrally bladed disks,are characterized by very low viscous material damping and make the flutter prediction much more critical.In that framework,a two-dimensional numerical study of a space turbine blisk featuring complex deformation of blades and high eigenfrequency(>40kHz)is performed.The simulations are based on unsteady Reynolds Averaged Navier Stokes computations linearized in the frequency domain and consist in the superposition of an unsteady linear(in time)pressure field,generated by a harmonic perturbation,upon a steady nonlinear(in space)flow.The aerodynamic damping coefficient is calculated over a range of nodal diameters,and the blades are predicted aeroelastically stable.However,violent changes occur and are rather critical since sudden and large deviations in stability appear.In that context,the nature of the waves propagating from the cascade are evaluated.Such an approach provides fundamental knowledge about the perturbations which can either propagate to the far-field(cut-on mode)or decay(cut-off mode).It is expected that the ability of the flow to damp or to amplify the blade motion is strongly affected by the way unsteady perturbations are transferred from the cascade to the far-field.The nature of the waves are first assessed from the aforementioned linearized results,then they are evaluated analytically and finally compared.A good agreement is found despite the strong assumptions of the analytical model.The results show a clear correlation between the cut-on/cut-off conditions and stability.The least stable configuration corresponds to cut-off mode at the inlet and no wave at the outlet.Without outgoing waves from the cascade,the blade is prone to be less stable:the energy from the blades vibration is necessarily dissipated or sent out by the cascade.

Subseasonal Prediction of Early-summer Northeast Asian Cut-off Lows by BCC-CSM2-HR and GloSea5

Northeast Asian cut-off lows are crucial cyclonic systems that can bring temperature and precipitation extremes over large areas.Skillful subseasonal forecasting of Northeast Asian cut-off lows is of great importance.Using two dynamical forecasting systems,one from the Beijing Climate Center(BCC-CSM2-HR)and the other from the Met Office(GloSea5),this study assesses simulation ability and subseasonal prediction skill for early-summer Northeast Asian cut-off lows.Both models are shown to have good ability in representing the spatial structure of cut-off lows,but they underestimate the intensity.The skillful prediction time scales for cut-off low intensity are about 10.2 days for BCC-CSM2-HR and 11.4 days for GloSea5 in advance.Further examination shows that both models can essentially capture the initial Rossby wave train,rapid growth and decay processes responsible for the evolution of cut-off lows,but the models show weaker amplitudes for the three-stage processes.The underestimated simulated strength of both the Eurasian midlatitude and East Asian subtropical jets may lead to the weaker local eddy-mean flow interaction responsible for the cut-off low evolution.

A new DRIE cut-off material in SOG MEMS process

The silicon on glasses process is a common preparation method of micro-electro-mechanical system inertial devices,which can realize the processing of thick silicon structures.This paper proposes that indium tin oxides(ITO)film can serve as a deep silicon etching cut-off layer because ITO is less damaged under the attack of fluoride ions.ITO has good electrical conductivity and can absorb fluoride ions for silicon etching and reduce the reflection of fluoride ions,thus reducing the foot effect.The removal and release of ITO use an acidic solution,which does not damage the silicon structure.Therefore,the selection of the sacrificial layer has an excellent effect in maintaining the shape of the MEMS structure.This method is used in the preparation of MEMS accelerometers with a structure thickness of 100μm and a feature size of 4μm.The over-etching of the bottom of the silicon structure caused by the foot effect is negligible.The difference between the simulated value and the designed value of the device characteristic frequency is less than 5%.This indicates that ITO is an excellent deep silicon etch stopper material.

Multifractal estimation of NMR T_(2) cut-off value in low-permeability rocks considering spectrum kurtosis: SMOTE-based oversampling integrated with machine learning

The transverse relaxation time (T_(2)) cut-off value plays a crucial role in nuclear magnetic resonance for identifying movable and immovable boundaries, evaluating permeability, and determining fluid saturation in petrophysical characterization of petroleum reservoirs. This study focuses on the systematic analysis of T_(2) spectra and T_(2) cut-off values in low-permeability reservoir rocks. Analysis of 36 low-permeability cores revealed a wide distribution of T_(2) cut-off values, ranging from 7 to 50 ms. Additionally, the T_(2) spectra exhibited multimodal characteristics, predominantly displaying unimodal and bimodal morphologies, with a few trimodal morphologies, which are inherently influenced by different pore types. Fractal characteristics of pore structure in fully water-saturated cores were captured through the T_(2) spectra, which were calculated using generalized fractal and multifractal theories. To augment the limited dataset of 36 cores, the synthetic minority oversampling technique was employed. Models for evaluating the T_(2) cut-off value were separately developed based on the classified T_(2) spectra, considering the number of peaks, and utilizing generalized fractal dimensions at the weight <0 and the singular intensity range. The underlying mechanism is that the singular intensity and generalized fractal dimensions at the weight <0 can detect the T_(2) spectral shift. However, the T_(2) spectral shift has negligible effects on multifractal spectrum function difference and generalized fractal dimensions at the weight >0. The primary objective of this work is to gain insights into the relationship between the kurtosis of the T_(2) spectrum and pore types, as well as to predict the T_(2) cut-off value of low-permeability rocks using machine learning and data augmentation techniques.

Lipoprotein (a) Cut-Off in Chronic Kidney Disease Patients with a History of Cardiovascular Disease in Center Hospital University Souro SANOU, Burkina Faso

Patients living with chronic kidney disease (CKD) are at high risk of cardiovascular events. Our aim in this study was to assess the cut-off value for lipoprotein (a) (Lp(a)) in CKD patients with a history of cardiovascular disease (CVD). This was a cross-sectional study. Variables including age, sex, history of CVD, body mass index and CKD stage, were collected during CKD patient’s first admission in the nephrology dialysis department. Blood samples were collected for quantitative determination of Lp(a) by immunoturbidimetric method. They were divided into two groups: CKD patients without history of CVD and CKD patients with history of CVD. Fisher’s exact test was used to assess associations with a significance level of 0.05%. Area under the curve (AUC) and new cut-off value for Lp(a) were identified by drawing Receiver Operating Characteristic (ROC) curve. A total of seventy CKD patients with median age of 43 years [minimum-maximum = 15 - 78 years] were included. Patients with history of CVD were 65.71% (46/70). New Lp(a) cut-off point in CKD patients with history of CVD was 66.50 nmol/L [sensitivity, 87.00%;specificity, 58.30%;AUC = 0.727;p = 0.000]. ROC curve demonstrated good performance of Lp(a) to screen CKD patients with history of CVD. Further research is needed to determine an LPA gene polymorphism’s contribution to increasing risk for CVD at each kidney disease stage.

基于cut-off方法刚性承台下群桩基础优化分析

针对刚性筏板下群桩基础优化设计问题进行分析,通过改变桩长分布来调整各桩的荷载分担,群桩分析采用基于弹性理论的积分方程方法,并通过cut-off方法来反映桩的弹塑性特性,实现群桩基础的弹塑性优化分析,改进了常规弹性分析方法的缺陷。算例分析表明,随着外荷载的不断增加,角桩首先达到极限荷载,对角桩超出极限荷载的部分进行重新分布,继而使得边桩逐渐达到极限承载状态,继续加载直至内桩也达到极限承载状态,从而引起桩筏基础的整体破坏。采用cut-off方法可以改进基础变刚度优化设计,使之与实际情况更为吻合。

利用RIBA试验确定HCV抗体检测的cut-off值及比较分析

目的利用重组蛋白免疫印迹分析(RIBA)实验,制定本实验室所用的日本希森美康公司的HISCL-5000型化学发光免疫分析仪及配套的相关试剂检测丙型肝炎病毒抗体(抗-HCV)的cut-off值。方法在2015年10月至2016年9月所检测的19341例患者标本中收集抗-HCV阳性标本80例,进行RIBA确认实验后进行分析,再利用ROC曲线计算出cut-off值。结果在本室HCV抗体阳性率为0.41%的数据中,RIBA结果可分为3种,其中25例(31.3%)为阴性,18例(22.5%)为不确定,37例(46.2%)为阳性。当截断值为3.95 COI时,灵敏度为81.1%,特异性为95.1%。另外当特异性为100%时,截断值为5.25 COI,灵敏度为73%。结论希森美康HISCL-5000型化学发光免疫分析仪及配套的相关试剂检测丙型肝炎病毒抗体(抗-HCV)与RIBA结果间呈正相关;当cut-off值为3.95 COI时,是一个适合本实验室的cut-off值。

Classifying moisture sources associated with snowfall in the mountains of Lesotho

An average of eight snowfall events occur each year in the eastern Lesotho Highlands.These snowfall events are typically associated with cut-off low(CoLs)systems and mid-latitude cyclones.However,the moisture sources of the snowfall are unclassified and unclear.The Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT)model,an air mass back trajectory model,has been used to evaluate moisture source waters locally in southern Africa and internationally in China and Europe.This study uses HYSPLIT to determine the source moisture of snow in Lesotho.A list of all 82 snowfall events in Lesotho spanning 2017 to 2022 was compiled using the Snow Report SA Instagram page,including the date and location of snowfall.A 72-hour back trajectory for each snowfall event was initiated for both Afriski and the whole of Lesotho.This amounts to models of moisture source trajectories for 28 and 82 snowfall days,respectively.These air mass pathways are classified according to their frequency per snowfall event,per month in the snow season,per year and for the full period.From this,associated moisture source regions and dominant air mass trajectories were identified.This study reports that the air mass trajectories associated with Afriski and Lesotho as a whole are very similar.The most common pathway of air mass trajectories transporting snow-bearing moisture to Lesotho was an inland trajectory from the northern regions of southern Africa.This pathway makes up 16.6%of all trajectories reported and is associated with the Angola Low,the Congo Air Boundary and the St.Helena High Pressure.

应用GSP筛查新生儿G6PDd的性能验证及cut-off值设定

目的对全自动荧光免疫分析仪(GSP)检测干血片葡萄糖-6-磷酸脱氢酶(G6PD)的性能进行验证,并初步建立该方法筛查葡萄糖-6-磷酸脱氢酶缺乏症(G6PDd)的cut-off值。方法前期确定验证方案,对试剂盒自带标准品B、D、E 3个浓度的标本,L、H两个浓度的质控品及试剂盒自带标准品B、C、D、E、F 5个浓度标本进行GSP系统的精密度、正确度和线性范围的验证。采用GSP和目前临床常规使用的Victor2D 1420型荧光免疫分析仪(半自动荧光免疫分析仪)同步检测2742例新生儿干血片G6PD水平,比较两种仪器结果,并使用百分位数分布及受试者工作特征(ROC)曲线初步建立中山市博爱医院产前诊断中心GSP筛查G6PDd时G6PD水平的cut-off值。结果应用GSP检测G6PD时,批内变异系数分别为2.09%、1.54%和1.90%,总变异系数分别为3.08%、1.72%和2.12%,分别小于厂家声明的3.40%和3.90%;质控浓度L的25份标本的测量总均值与靶值的相对偏差为3.84%,质控浓度H的25份标本的测量总均值与靶值的相对偏差为3.44%;5个浓度标本的检测值和理论值的线性回归方程为Y=1.0082 X+0.0125,决定系数(R^(2))为0.9991,R^(2)>0.995,线性相关性良好。标本总体P_(5)的G6PD水平为20.10 U/dL。两种仪器的一致性良好。结论GSP应用于中山市新生儿G6PD检测中,精密度、准确度、线性范围均达到了厂家声明的检测性能,可常规用于新生儿G6PDd筛查。该中心初步采用的GSP新生儿G6PDd筛查的cut-off值为20.10 U/dL。

Numerical stress-deformation analysis of cut-off wall in clay-core rockfill dam on thick overburden

The cut-off wall in a clay-core rockfill dam built on a thick overburden layer is subjected to a large compressive pressure under the action of the loads such as the dead weight of both the dam and the overburden layer, the frictional force induced by the differential settlement between the cut-off wall and surrounding soils, and the water pressure. Thus, reduction of the stress of the cut-off wall has become one of the main problems for consideration in engineering design. In this paper, numerical analysis of a core rockfill dam built on a thick overburden layer was conducted and some factors influencing the stress-strain behaviors of the cut-off wall were investigated. The factors include the improvement of the overburden layer, the modeling approach for interfacial contact between the cut-off wall and surrounding soils, the modulus of the cut-off wall concrete, and the connected pattern between the cut-off wall and the clay core. The result shows that improving the overburden layer,selecting plastic concrete with a low modulus and high strength, and optimizing the connection between the cut-off wall and the clay core of the dam are effective measures of reducing the deformations and compressive stresses of the cut-off wall. In addition, both the Goodman element and the mud-layer element are suitable for simulating the interfacial contact between the cut-off wall and surrounding soils.

A case study of a Kuroshio main path cut-off event and impacts on the South China Sea in fall-winter 2013–2014

This study examines a Kuroshio main path(KMP) cut-off event east of Taiwan Island occurred in fall-winter2013–2014 and its impacts on the South China Sea(SCS) by analyzing satellite altimetry and mooring observations. Satellite altimeter sea level anomaly(SLA) images reveal a complete process that a huge cyclonic eddy(CE) from the Pacific collided with the Kuroshio and the western boundary from 15 October 2013 to 15 January 2014. Mooring observations evidenced that the Kuroshio upper ocean volume transport was cut off more than 82% from 17×106 m^3/s in September to 3×106 m^3/s in November 2013. The KMP cut-off event caused the Kuroshio branching and intruding into the SCS and strengthened the eddy kinetic energy in the northern SCS west of the Luzon Strait. Using the total momentum as a dynamic criterion to determine the role of eddy collision with the Kuroshio reasonably explains the KMP cut-off event.

Dynamic monitoring of menopause hormone therapy and defining the cut-off value of endometrial thickness during uterine bleeding

The aim of this study was to evaluate the effects of low-dose tibolone therapy on ovarian area, uterine volume and endometrial thickness, and define the cut-off value of endometrial thickness for curettage during uterine bleeding. We followed 619 postmenopausal women, aged 40-60 years, for two years. There were 301 subjects in the low-dose tibolone treatment group and 318 subjects in the control group. The ovarian area, uterine volume and endometrial thickness in all participants were measured by transvaginal ultrasound prior to, one and two years post enrollment, respectively. Endometrial specimens were collected from all subjects with abnormal uterine bleeding during the follow-up period. We found that the uterine volume in the treatment group was greater than that in the control group, and the difference was significant （P〈0.05）, but there were no significant differences in ovarian area and endometrial thickness between the two groups （P〉0.05）. When the cut-off value for endometrial thickness was 7.35 ram, the sensitivity and specificity were 100% and 79.07%, respectively, and 85.71% and 93.02% when 7.55 mm was set as the cut-offduring tibolone therapy. The results indicate that low-dose tibolone therapy may postpone uterine atrophy and the cut-off value of endometrial thickness may be appropriately adjusted for curettage.

Suppressing the weakly bound states in the photoassociation dynamics by using a frequency cut-off laser pulse

The photoassociation dynamics of ultracold lithium atoms controlled by a cut-off pulse has been investigated theoretically by solving numerically the time-dependent Schr6dinger equation using the mapped Fourier grid method. The frequency components of the laser pulse close to the atomic resonance are partly cut off. Compared with the typical Gauss-type pulses, the cut-off pulse is helpful to suppress efficiently the weakly bound states and prepare the associated molecules in the lower vibrational states. Especially, the dependence of photoassociation probability on the cut-off position of the laser pulse is explored.

The Impact of Cut-off Lows on Ozone in the Upper Troposphere and Lower Stratosphere over Changchun from Ozonesonde Observations

In situ measurements of the vertical structure of ozone were made in Changchun （43.53°N, 125.13°E）, China, by the Institute of Atmosphere Physics, in the summers of 2010-13. Analysis of the 89 validated ozone profiles shows the vari- ation of ozone concentration in the upper troposphere and lower stratosphere （UTLS） caused by cut-off lows （COLs） over Changchun. During the COL events, an increase of the ozone concentration and a lower height of the tropopause are observed. Backward simulations with a trajectory model show that the ozone-rich airmass brought by the COL is from Siberia. A case study proves that stratosphere-troposphere exchange （STE） occurs in the COL. The ozone-rich air mass transported from the stratosphere to the troposphere first becomes unstable, then loses its high ozone concentration. This process usually happens during the decay stage of COLs. In order to understand the influence of COLs on the ozone in the UTLS, statistical analysis of the ozone profiles within COLs, and other profiles, are employed. The results indicate that the ozone concentrations of the in-COL profiles are significantly higher than those of the other profiles between ±4 km around the tropopause. The COLs induce an increase in UTLS column ozone by 32% on average. Meanwhile, the COLs depress the lapse-rate tropopause （LRT）/dynamical tropopause height by 1.4/1.7 km and cause the atmosphere above the tropopause to be less stable. The influence of COLs is durable because the increased ozone concentration lasts at least one day after the COL has passed over Changchun. Furthermore, the relative coefficient between LRT height and lower stratosphere （LS） column ozone is -0.62, which implies a positive correlation between COL strength and LS ozone concentration.

Effect of copper slag recovery on hydrometallurgical cut-off grades considering environmental aspects

Determining the hydrometallurgical cut-off grades specifies the destination of low grade materials and this is subjected to more benefits in mining. Copper production rate is considered as one of the fundamental issues in hydrometallurgical cut-off grades determination. Slags are remarked as one of the main sources of copper. It is not only regarded as a waste but also identified as another resource extracting base metals. Slags are characterized by copper high grade. Thus, slag copper recovery can be led to different cut-off grades and net present value(NPV). The current research scrutinizes the effect of slag recovery by both flotation and hydrometallurgical methods on the hydrometallurgical cut-off grades. For this purpose, the optimum cut-off grade algorithms of hydrometallurgical methods are developed by considering associated environmental parameters, incomes and also the costs. Then, their optimum amounts are calculated with NPV maximization as an objective function. The results indicate that considering slag copper recovery in the hydrometallurgical cut-off grade algorithms reduces the environmental costs caused by slag dumping and leads to more NPV by 9%.

Collector optimization for tradeoff between breakdown voltage and cut-off frequency in SiGe HBT

As is well known, there exists a tradeoff between the breakdown voltage BVcEO and the cut-off frequency fT for a standard heterojunction bipolar transistor （HBT）. In this paper, this tradeoff is alleviated by collector doping engineering in the SiGe HBT by utilizing a novel composite of P＋ and N- doping layers inside the collector-base （CB） space-charge region （SCR）. Compared with the single N-type collector, the introduction of the thin P＋ layers provides a reverse electric field weakening the electric field near the CB metallurgical junction without changing the field direction, and the thin N layer further effectively lowers the electric field near the CB metallurgical junction. As a result, the electron temperature near the CB metallurgical junction is lowered, consequently suppressing the impact ionization, thus BVcEO is improved with a slight degradation in fT. The results show that the product of fTXBVcEo is improved from 309.51 GHz.V to 326.35 GHz.V.

A convenient method for the determination of molecular weight cut-off of ultrafiltration membranes

With the rapid increase of water contamination,membrane separation technology and their corresponding molecular weight cut-off(MWCO) evaluation method become more necessary.In this study,Panax notoginseng saponins was used as a new standard marker to determinate ultrafiltration(UF) membrane MWCOs,series of Millipore membranes were selected as control group to analyze and calculate the relationship between retention rate and MWCOs with exponential or logarithmic equation.A new and convenient method was provided for determining the membrane MWCO by modeling analysis retention rate with MWCOs,and the regression coefficients >0.990.The feasibility and practicability of established method was verified by different manufactures' membrane and dextrans.In the detection progress,as the main ingredient of Panax notoginseng saponins,Notoginsenoside R_1,Ginsenoside Rg_1,Ginsenoside Rb_1 and Ginsenoside Rd with different surface activity,the MWCO range of UF membranes can be divided into two zones mainly due to the retention rate difference among Notoginsenoside R_1,Ginsenoside Rg_1,Ginsenoside Rb_1 and Ginsenoside Rd.Zone 1,1000-10000;and Zone II,10000-100000.Thus,the new method would be helpful to improve the applicability of UF membrane in separation technology.

Effect of Cut-Off Frequency of Butterworth Filter on Detectability and Contrast of Hot and Cold Regions in Tc-99m SPECT

In SPECT, noise is one of the major limitations that degrade image quality. To suppress the noisy signals in an image, digital filters are most commonly applied. However, in SPECT image reconstruction, selection of an appropriate filter and its functions has always remained a difficult task. In this work an attempt was made to investigate the effects of varying cut-off frequencies and in keeping the order of Butterworth filter constant on detectability and contrast of hot and cold re-gions images. A new insert simulating hot and cold regions which provides similar views in a reconstructed image was placed in the phantom’s cylindrical source tank and imaged. Tc-99m radionuclide was distributed uniformly in the phantom. SPECT data were collected in a 20% energy window centered at 140 keV by a Philips ADAC Forte dual head gamma camera mounted with a LEHR collimator. Images were generated by using the filtered backprojection technique. A Butterworth filter of order 5 with cut-off frequencies 0.35 and 0.45 cycles·cm-1 was applied. Images were examined in terms of hot and cold regions, detectability and contrast. Results show that the hot and cold regions’ detectability and contrast vary with the change of cut-off frequency. With a 0.45 cycles·cm-1 cut-off frequency, a significant enhancement in contrast of cold regions was achieved as compared to a 0.35 cycles·cm-1 cut-off frequency. Furthermore, the detectability of hot and cold regions improved with the use of a 0.45 cycles·cm-1 cut-off frequency. In conclusion, image quality of hot and cold regions affected in a different way with a change of cut-off frequency. Thus, care should be taken in selecting the filter cut-off frequency prior to reconstruction of images;particularly, when both types of regions are expected in the reconstructed image.