MAPOD Analysis in Eddy Current Testing of Flaws Considering Multiple Response Signals and Multiple Flaw Parameters

The reliability of the eddy current testing (ECT) in flaw detection is quantitatively evaluated by theprobability of detection (POD). Precise and efficient modeling of POD gives direction for the implement of ECTon sites to avoid false or missing flaw detection. Traditional POD analysis focuses on single uncertain factor orsingle response signal with limited credibility in engineering. This paper considers multiple response signals andmultiple flaw parameters to perform POD. The flaw length, the flaw depth, the coil impedance, and the magneticflux density are comprehensively studied under various lift-off distances. A finite element model (FEM) of ECT isestablished and verified with experiments to obtain sufficient simulation data for discrete POD modeling. Thecontinuous POD function is then fitted based on the discrete values to show the superiority of integrating multiplefactors. A comparison with conventional POD analysis further demonstrates the higher reliability of ECT flawdetection considering multiple flaw parameters and multiple response signals, especially for small flaws.

Is transcranial direct current stimulation a potential method for improving response inhibition?

Inhibitory control of movement in motor learning requires the ability to suppress an inappropriate action, a skill needed to stop a planned or ongoing motor response in response to changes in a variety of environments. This study used a stop-signal task to determine whether transcranial direct-current stimulation over the pre-supplementary motor area alters the reaction time in motor inhibition. Forty healthy subjects were recruited for this study and were randomly assigned to either the transcranial direct-current stimulation condition or a sham-transcranial direct-current stimulation condition. All subjects consecutively performed the stop-signal task before, during, and after the delivery of anodal transcranial direct-current stimulation over the pre-supplementary motor area （pre-transcranial direct-current stimulation phase, transcranial direct-current stimulation phase, and post-transcranial direct-current stimulation phase）. Compared to the sham condition, there were significant reductions in the stop-signal processing times during and after transcranial direct-current stimulation, and change times were significantly greater in the transcranial direct-current stimulation condition. There was no significant change in go processing-times during or after transcranial direct-current stimulation in either condition. Anodal transcranial direct-current stimulation was feasibly coupled to an interactive improvement in inhibitory control. This coupling led to a decrease in the stop-signal process time required for the appropriate responses between motor execution and inhibition. However, there was no transcranial direct-current stimulation effect on the no-signal reaction time during the stop-signal task. Transcranial direct-current stimulation can adjust certain behaviors, and it could be a useful clinical intervention for patients who have difficulties with response inhibition.

Research on the Dynamic Response of Submerged Floating Tunnels to Wave Currents and Traffic Load

Submerged floating tunnel(SFTs)are typically subjected to complex external environmental and internal loads such as wave currents and traffic load.In this study,this problem is investigated through a finite element method able to account for fluid-structure interaction.The obtained results show that increasing the number of vehicles per unit length enhances the transverse vibrational displacements of the SFT cross sections.Under ultimate traffic load condition,one-way and two-way syntropic distributions can promote the dynamic responses of SFTs whereas two-way reverse distributions have the opposite effect.

Wave-current-induced soil response in marine sediments

This letter presents a new analytical approximation for wave （current）-induced dynamic soil response in marine sediments. In the model, the third-order approximation for wave-current interactions is employed for the flow model, while Biot＇s dynamic poro-elastic model is used to simulate the porous flow in a seabed. The newly analytical solution is validated with the field observations. Based on the solution, effects of currents and wave-nonlinearity on soil response are examined and a parametric study will be carried out to examine the influence of currents on the liquefaction potential. C 2013 The Chinese Society of Theoretical and Applied Mechanics. [doi： 10.1063/2.1301202]

Dynamic Response Analysis of Risers Subjected to Combined Wave and Current Loading

A dynamic response analysis in the frequency domain is presented for risers subjected to combined wave and current loading. Considering the effects of current, a modified wave spectrum is adopted to compute the linearized drag force. An additional drag force convolution term is added to the linearized drag force spectrum, therefore the error is reduced which arises from the truncation of higher order terms in the drag force auto-correlation function. An expression of linearized drag force spectrum is given taking the relative velocity into account. It is found that the additional term is a fold convolution integral. In this paper dynamic responses of risers are investigated, while the influence of floater motion on risers is considered. The results demonstrate that the accuracy of the present method reaches the degree required in time domain analysis.

Alternating response of spin current in a magnetic-oscillating quantum dot

We investigate alternating response of the spin current in a quantum dot system coupled to a normal metal electrode, to which an alternating driving voltage and a pumping rotating magnetic field are applied. The expression of the time-averaged spin current and its differential is obtained based on a non-equilibrium Green＇s function method. We find that for a given rotating frequency, the spin current increases rapidly and appears to have small steps when the driven frequency increases. As the driven frequency is further increasing, the spin current can be significantly enhanced and approaches a stable value. The photon-assisted processes bring about interesting features of spin current. The influence of the gate voltage and temperature on the spin current is examined in detail.

Analysis of the Current Structure and Response Strategies of Intensive Vegetable Seedling Cultivation in Hebei Province

In the last few years, vegetable industry developed rapidly in Hebei province, intensive raising seedling as its main component, also entered a period of rapid development. The background and characteristics, the current situation and existed questions of intensive seedling cultivation were analyzed. A series of developmental ideas and response strategies for developing more quickly in Hebei Province were put forward.

An Adaptive Response Compensation Technique for the Constant-Current Hot-Wire Anemometer

An adaptive response compensation technique has been proposed to compensate for the response lag of the constant-current hot-wire anemometer (CCA) by taking advantage of digital signal processing technology. First, we have developed a simple response compensation scheme based on a precise theoretical expression for the frequency response of the CCA (Kaifuku et al. 2010, 2011), and verified its effectiveness experimentally for hot-wires of 5 μm, 10 μm and 20 μm in diameter. Then, another novel technique based on a two-sensor probe technique—originally developed for the response compensation of fine-wire thermocouples (Tagawa and Ohta 1997;Tagawa et al. 1998)—has been proposed for estimating thermal time-constants of hot-wires to realize the in-situ response compensation of the CCA. To demonstrate the usefulness of the CCA, we have applied the response compensation schemes to multipoint velocity measure- ment of a turbulent wake flow formed behind a circular cylinder by using a CCA probe consisting of 16 hot-wires, which were driven simultaneously by a very simple constant-current circuit. As a result, the proposed response compensation techniques for the CCA work quite successfully and are capable of improving the response speed of the CCA to obtain reliable measurements comparable to those by the commercially-available constant-temperature hot-wire anemometer (CTA).

Theoretical study of a group IV p–i–n photodetector with a flat and broad response for visible and infrared detection

We report a theoretical study of a broadband Si/graded-SiGe/Ge/Ge0.9Sn0.1 p–i–n photodetector with a flat response based on modulating thickness of the layers in the active region.The responsivity of the photodetector is about 0.57 A/W in the range of 700 to 1800 nm.This structure is suitable for silicon-based epitaxial growth.Annealing is technically applied to form the graded-SiGe.The photodetector reaches a cut-off wavelength at^2300 nm and a low dark-current density under 3 V reverse bias about 0.17 mA/cm^2 is achieved theoretical at room temperature.This work is of great significance for silicon-based detection and communication,from visible to infrared.

Electric field distribution and effective nonlinear AC and DC responses of graded cylindrical composites

The perturbation method is used to study the localization of electric field distribution and the effective nonlinear response of graded composites under an external alternating-current（AC） and direct-current（DC） electric field E app = E 0（1 ＋ sin ωt）.The dielectric profile of the cylindrical inclusions is modeled by function ε i（r） = C k r k（r ≤ a）,where r is the radius of the cylindrical inclusion,and C k,k,a are parameters.In the dilute limit,the local potentials and the effective nonlinear responses at all harmonics are derived.Meanwhile,the general effective nonlinear responses are also derived and compared with the effective nonlinear responses at harmonics under the AC and DC external field.It is found that the effective nonlinear AC and DC responses at harmonics can be calculated by those of the general effective nonlinear of the graded composites under the external DC electric field.Moreover,the obtained local electrical fields show that the electrical field distribution in the cylindrical inclusions is controllable,and the maximum of the electric field inside the cylinder is at its center.

SC response characteristics of two kinds of coagulant

Automatic coagulant dosage control with streaming current (SC) technique is introduced in this paper. Aluminum and ferric coagulants are widely used in surface water treatment. The SC response characteristics of P AlCl 3 aluminum coagulant and P FeCl 3 ferric coagulant were investigated in this work. Bench scale water treatment results were obtained from jar tests including rapid mixing, flocculation and undisturbed sedimentation. Results showed that aluminum coagulant is more sensitive than ferric coagulant to SC response.

AB050.Neuronal response to visual contrast varies as function of the cortical layer

Background:For years,studies using several animal models have highlighted the predominant role of the primary visual area in visual information processing.Its six cortical layers have morphological,hodological and physiological differences,although their roles regarding the integration of visual contrast and the messages sent by the layers to other brain regions have been poorly explored.Given that cortical layers have distinct properties,this study aims to understand these differences and how they are affected by a changing visual contrast.Methods:A linear multi-channel electrode was placed in the primary visual cortex(V1)of the anesthetized mouse to record neuronal activity across the different cortical layers.The laminar position of the electrode was verified in real time by measuring the current source density(CSD)and the multi-unit activity(MUA),and confirmed post-mortem by histological analysis.Drifting gratings varying in contrast enabled the measurement of the firing rate of neurons throughout layers.We fitted this data to the Naka-Rushton equations,which generated the contrast response function(CRF)of neurons.Results:The analysis revealed that the baseline activity as well as the rate of change of neural discharges(the slope of the CRF)had a positive correlation across the cortical layers.In addition,we found a trend between the cortical position and the contrast evoking the semi-saturation of the activity.A significant difference in the maximum discharge rate was also found between layers II/III and IV,as well as between layers II/III and V.Conclusions:Since layers II/III and V process visual contrast differently,our results suggest that higher cortical visual areas,as well subcortical regions,receive different information regarding a change in visual contrast.Thus,a contrast may be processed differently throughout the different areas of the visual cortex.

表面活性剂对电镀锌-铟合金性能的影响

目的研究表面活性剂十六烷基三甲基溴化铵(CTAB)与聚乙二醇2000(PEG)对Zn-In合金镀层性能的影响。方法采用单因素试验确定了CTAB与PEG的含量,使用响应曲面法建立耐蚀性能测试参数与表面活性剂含量之间的数学模型。实验采用线性电位扫描,并采用维氏显微硬度仪,接触角测试仪、SEM、EDS和XRD对电镀锌-铟合金镀层的析氢行为、硬度、表面湿润性、表面形貌、元素种类以及物相组成进行表征。结果通过响应曲面法建立了耐腐蚀性能参数与CTAB和PEG含量之间的数学模型,获得复合表面活性剂组成,镀层的耐蚀性良好;接触角测试结果显示,未加添加剂的膜层表面湿润角为56°,优化后镀层表面湿润角仅为25°,具有较好的亲水性,且由于晶粒细化使试样硬度提升;镀层主要由Zn、In、C、O等元素组成,加入表面活性剂对镀层的影响不大,金属铟的生长晶面主要为(101)和(102)晶面。结论最佳添加复合表面活性剂的比例为CTAB0.33g/L,PEG0.87g/L,电镀液中添加表面活性剂后能够有效提升镀层耐腐蚀性能,有效抑制了析氢反应。

Metal–organic framework wafer enabled fast response radiation detection with ultra-low dark current

Semiconductive metal–organic frameworks(MOFs)have attracted great interest for the electronic applications.However,dark currents of present hybrid organic–inorganic materials are 1000–10,000 times higher than those of commercial inorganic detectors,leading to poor charge transportation.Here,we demonstrate a ZIF-8(Zn(mim)_(2),mim=2-methylimidazolate)wafer with ultra-low dark current of 1.27 pA·mm^(-2) under high electric fields of 322 V·mm^(-1).The isostatic pressing preparation process provides ZIF-8 wafers with good transmittance.Besides,the presence of redox-active metals and small spatial separation between components promotes the charge hopping.The ZIF-8-based semiconductor detector shows promising X-ray detection sensitivity of 70.82μC·Gy^(-1)·cm^(-2) with low doses exposures,contributing to superior X-ray imaging capability with a relatively high spatial resolution of 1.2 lp·mm^(-1).Simultaneously,good peak discrimination with the energy resolution of~43.78%is disclosed when the detector is illuminated by uncollimated 241Am@5.48 MeVα-particles.These results provide a broad prospect of MOFs for future radiation detection applications.

复杂风-浪-流环境下海洋牧场交通栈道施工阶段钢管桩受力行为研究

为明确复杂海洋环境下钢管桩的受力行为,借助于有限元数值模拟,采用流固耦合的方法,进行施工阶段钢管桩在风-浪-流耦合作用下的受力行为研究,总结得到不同参数下钢管桩的动力响应规律。首先,借助有限元软件ANSYS Workbench的Fluent模块,通过加载UDF程序进行二次开发,对数值模型进行了速度入口、压力出口、入口体积和出口体积等边界条件的设置,实现风-浪-流耦合环境场的构造;其次,基于风-浪-流耦合数值环境场,对单向和双向流固耦合作用下风-浪-流耦合环境与钢管桩的动力响应结果进行了对照分析,结果表明双向流固耦合方法更符合实际海洋环境下钢管桩受力状态;最后,对施工阶段钢管桩进行动力响应研究,分析了桩径、斜度、长度、截面形状、水深、环境等参数影响下钢管桩动力响应规律,并对钢管桩周围流体域进行分析,得到不同斜度钢管桩周围流体域运动规律。

海阳市中小学生流行性感冒防控知信行调查情况分析

目的探讨海阳市中小学生流行性感冒防控知信行现状,为科学开展疾病防控健康教育提供依据。方法采用随机分层整群抽样方法,2023年6—8月随机从海阳市下辖的街道和镇中抽取4个地区,再从中分别抽取高中、初中和小学各1所,每所学校随机抽取1个年级中的1个班级,将抽取的全部学生作为调查对象,共计12个班级507名学生。利用问卷对学生流行性感冒防控的健康知识、应对态度和预防行为展开调查并统计分析。结果知信行3项中,小学、初中与高中学生预防行为合格率最高,应对态度合格率最低。小学、初中与高中学生健康知识合格率分别为45.66%、68.67%、72.02%,小学、初中与高中学生应对态度合格率分别为42.20%、59.04%、55.95%,差异有统计学意义(P<0.05)。男生预防行为合格率为76.40%,低于女生的88.33%,差异有统计学意义(P<0.05)。城市学生健康知识、应对态度与预防行为合格率分别为69.44%、58.80%、87.96%,均高于乡镇学生的56.36%、47.42%、77.66%,差异有统计学意义(P<0.05)。结论海阳市中小学生流行性感冒防控知信行整体水平不高,不同教育层次、性别与地区学生流行性感冒防控的信知行水平存在差异,建议进一步加强流行性感冒防控宣教,尤其要端正学生流感防控的态度,同时持续提高学生流感防控知识水平,以更好地保障学生群体健康权益。

Experimental Study on Hydrodynamic Characteristics of Vertical-Axis Floating Tidal Current Energy Power Generation Device

To study the characteristics of attenuation, hydrostatic towage and wave response of the vertical-axis floating tidal current energy power generation device （VAFTCEPGD）, a prototype is designed and experiment is carried out in the towing tank. Free decay is conducted to obtain attenuation characteristics of the VAFTCEPGD, and characteristics of mooring forces and motion response, floating condition, especially the lateral displacement of the VAFTCEPGD are obtained from the towing in still water. Tension response of the #1 mooring line and vibration characteristics of the VAFTCEPGD in regular waves as well as in level 4 irregular wave sea state with the current velocity of 0.6 m/s. The results can be reference for theoretical study and engineering applications related to VAFTCEPGD.

Optimization of pulsed current gas tungsten arc welding process parameters to attain maximum tensile strength in AZ31B magnesium alloy

An empirical relationship to predict tensile strength of pulsed current gas tungsten arc welded AZ31B magnesium alloy was developed. Incorporating process parameters such as peak current, base current, pulse frequency and pulse on time were studied. The experiments were conducted based on a four-factor, five-level, central composite design matrix. The developed empirical relationship can be effectively used to predict the tensile strength of pulsed current gas tungsten arc welded AZ31B magnesium alloy joints at 95% confidence level. The results indicate that pulse frequency has the greatest influence on tensile strength, followed by peak current, pulse on time and base current.

Flow separation control over an airfoil using continuous alternating current plasma actuator

The flow separation control over an NACA 0015 airfoil using continuous alternating current(AC)dielectric barrier discharge(DBD)plasma actuator is investigated experimentally and numerically.This work is intended to report some observations made from our experiment,to which little attention is paid in the previous studies,but which is thought to be important to the understanding of control of complex flow separation with AC DBD.To this end,the response of separated flow to AC plasma actuation is visualized through the time-resolved particle image velocimetry(PIV)measurement,whereas numerical simulation is carried out to complement the experiment.The flow control process at chord-based Reynolds number(Re)of 3.31×105 is investigated.It is found that the response of external flow to plasma forcing is delayed for up to tens of milliseconds and the delay time increases with angle of attack increasing.Also observed is that at the intermediate angle of attack near stall,the forced flow features a well re-organized flow pattern.However,for airfoil at high post-stall angle of attack,the already well suppressed flow field can recover to the massively separated flow state and then reattach to airfoil surface with the flow pattern fluctuating between the two states in an irregular manner.This is contrary to one’s first thought that the forced flow at any angles of attack will become well organized and regular,and reflects the complexity of flow separation control.

A Plus Type CC-Based Current-Mode Universal Biquad

This paper introduces a current-mode universal biquad circuit using only plus type CCs(current conveyors)(i.e.DVCCs(differential voltage current conveyors)and CCIIs(second generation current conveyors)).The circuit enables LP(low-pass),BP(band-pass),HP(high-pass),BS(band-stop)and AP(all-pass)responses by the selection and/or addition of the input and output currents without any component matching constraints.Moreover the circuit parametersω0 and Q can be set orthogonally adjusting the circuit components.A design example is given together with simulation responses by PSPICE.