Artificial neural network algorithm for pulse shape discrimination in 2πα and 2πβ particle surface emission rate measurements

To enhance the accuracy of 2πα and 2πβ particle surface emission rate measurements and address the identification issues of nuclides in conventional methods, this study introduces two artificial neural network(ANN) algorithms: back-propagation(BP) and genetic algorithm-based back-propagation(GA-BP). These algorithms classify pulse signals from distinct α and β particles. Their discrimination efficacy is assessed by simulating standard pulse signals and those produced by contaminated sources, mixing α and β particles within the detector. This study initially showcases energy spectrum measurement outcomes, subsequently tests the ANNs on the measurement and validation datasets, and contrasts the pulse shape discrimination efficacy of both algorithms. Experimental findings reveal that the proportional counter's energy resolution is not ideal, thus rendering energy analysis insufficient for distinguishing between 2πα and 2πβ particles. The BP neural network realizes approximately 99% accuracy for 2πα particles and approximately 95% for 2πβ particles, thus surpassing the GA-BP's performance. Additionally, the results suggest enhancing β particle discrimination accuracy by increasing the digital acquisition card's threshold lower limit. This study offers an advanced solution for the 2πα and 2πβ surface emission rate measurement method, presenting superior adaptability and scalability over conventional techniques.

Plastic Mechanism of Multi-pass Double-roller Clamping Spinning for Arc-shaped Surface Flange

Compared with the conventional single-roller spinning process, the double-roller clamping spinning（DRCS） process can effectively prevent the sheet metal surface wrinkling and improve the the production efficiency and the shape precision of final spun part. Based on ABAQUS/Explicit nonlinear finite element software, the finite element model of the multi-pass DRCS for the sheet metal is established, and the material model, the contact definition, the mesh generation, the loading trajectory and other key technical problems are solved. The simulations on the multi-pass DRCS of the ordinary Q235A steel cylindrical part with the arc-shaped surface flange are carried out. The effects of number of spinning passes on the production efficiency, the spinning moment, the shape error of the workpiece, and the wall thickness distribution of the final part are obtained. It is indicated definitely that with the increase of the number of spinning passes the geometrical precision of the spun part increases while the production efficiency reduces. Moreover, the variations of the spinning forces and the distributions of the stresses, strains, wall thickness during the multi-pass DRCS process are revealed. It is indicated that during the DRCS process the radical force is the largest, and the whole deformation area shows the tangential tensile strain and the radial compressive strain, while the thickness strain changes along the generatrix directions from the compressive strain on the outer edge of the flange to the tensile strain on the inner edge of the flange. Based on the G-CNC6135 NC lathe, the three-axis linkage computer-controlled experimental device for DRCS which is driven by the AC servo motor is developed. And then using the experimental device, the Q235A cylindrical parts with the arc-shape surface flange are formed by the DRCS. The simulation results of spun parts have good consistency with the experimental results, which verifies the feasibility of DRCS process and the reliability of the finite element model for DRCS.

SYNTHESIS OF AMPHIPHILIC COMB-SHAPED COPOLYMERS USED FOR SURFACE MODIFICATION OF PVDF MEMBRANES

The synthesis of a novel amphiphilic comb-shaped copolymer consisting of a main chain of styrene-(N-(4- hydroxyphenyl) maleimide)(SHMI) copolymer and poly(ethylene glycol) methyl ether methacrylate(PEGMA) side groups was achieved by atom transfer radical polymerization(ATRP).The amphiphilic copolymers were characterized by ~1H-NMR, Fourier transform infrared(FTIR) spectroscopy and gel permeation chromatography(GPC).From thermogravimetric analysis (TGA),the decomposition temperature of SHMI-g-PEGMA is lower ...

Surface Effects on the Diffraction of P Wave by an Arbitrary Shaped Cavity

This paper presents the effects of surface effects in the cavity of variable curvature. The wave function expansion method and the conformal mapping method are used in the solution of dynamic stress concentration factor around an irregularly shaped cavity at nano-scale. The stress boundary conditions on the surface are obtained by using the generalized Young-Laplace equation. The results show that the degree of stress concentration becomes more obvious with curvature increasing. Taking the elliptical cavity as an example, the influence of the ration of the major and minor axis of the ellipse, the numbers of the incident wave and the surface effects on the dynamic stress concentration factor are analyzed. The ration of the major and minor axis, the incident wave frequency and the surface effects show the pronounced effects on the dynamic stress concentration distributions.

Detection of Veneer Moisture Content by Surface-circle-shaped Resistance

This paper, with veneer as a particularly detected target, deals with a new method for detecting veneer moisture content. Surface resistance is measured by the fixed pressure, circle-shaped point and surface-touched detector. With the help of the computer, the veneer moisture and its distribution will be detected in a faster way with no harm to the veneer surface.

Global Continuity Adjustment and Local Shape Optimization Technique for Complex Trimmed Surface Model

Smoothly stitching multiple surfaces mainly represented by B-spline or NURBS together is an extremely important issue in complex surfaces modeling and reverse engineering. In recent years, a lot of progress has been made in smooth join of non-trimmed surface patches, while there has been seldom research on smoothly stitching trimmed surface patches together. This paper studies the problem of global continuity adjustment, damaged hole repair and local shape optimization for complex trimmed surface model, and presents a uniform scheme to deal with continuity adjustment of trimmed surfaces and geometric repair of local broken region. Constrained B-spline surface refitting technique and trim calculation are first utilized to achieve global G^1 continuity, and then local shape optimization functional is adopted to reduce fitting error and improve local quality of refitted surface patch. The proposed approach is applied to a discontinuity ship hull surface model with an irregular hole, and the result demonstrates the validation of our method. Furthermore, on the premise of global continuity, the proposed locally repairing damaged surface model provides a better foundation for following research work, such as topology recovery technique for complex surface model after geometric repair.

Research on Complexity of Surface Undulating Shapes of Rock Joints

The surface undulating shapes of rock joints have been described qualitatively or experimental quantitatively for a long time. The non determined describing method can not fit quantitative evaluation of mechanical parameters of rock joints in engineering. In this paper, relative amplitude ( R A) is chosen as a quantitative describing index of surface measurement of 1 023 surface undulating curves which conducted by profile curve device(PCD). We discuss the nonuniformity,anisotropy and unhomogeneity of surface undulating shapes of joints. A new method that analyzes the complexity of surface undulating shapes of rock joints directional statistically in various rock joints is also put forward.

Possible observation of shape-coexisting configurations in even–even midshell isotones with N=104:a systematic total Routhian surface calculation

Systematic total Routhian surface calculations for even–even N = 104 midshell isotones with 66≤Z≤82 have been carried out based on a more realistic diffuse-surface deformed Woods–Saxon nuclear potential in (β_2, γ, β_4) deformation space, focusing on the rotation-induced shapecoexisting phenomena. As an example and basic test, the oblate property at the ground state in ^(184)Hg is well reproduced and the microscopic origin is analyzed from the single-particle structure. The present calculated results are compared with available experimental information, showing a good agreement. It is systematically found that in this isotonic chain several bands with different shapes(e.g., prolate, oblate and superdeformed prolate bands, seven non-collective band) may show a strong competition and coexisting phenomenon at a certain domain of the rotational frequency.

RECONSTRUCTION OF WELD POOL SURFACE BASED ON SHAPE FROM SHADING

A valid image-processing algorithm of weld pool surface reconstruction according to an input image of weld pool based on shape from shading （SFS） in computer vision is presented. The weld pool surface information is related to the backside weld width, which is crucial to the quality of weld joint. The image of weld pool is recorded with an optical sensing method. Firstly, the reflectance map model, which specifies the imaging process, is estimated. Then, the algorithm of weld pool surface reconstruction based on SFS is implemented by iteration scheme and speeded by hierarchical structure. The results indicate the accuracy and effectiveness of the approach.

Interactive Restoration of Three-Dimensional Implicit Surface with Irregular Parts

Implicit surface generation based on the interpolation of surface points is one of the well-known modeling methods in the area of computer graphics.Several methods for the implicit surface reconstruction from surface points have been proposed on the basis of radial basis functions,a weighted sum of local functions,splines,wavelets,and combinations of them.However,if the surface points contain errors or are sparsely distributed,irregular components,such as curvature-shaped redundant bulges and unexpectedly generated high-frequency components,are commonly seen.This paper presents a framework for restoring irregular components generated on and around surfaces.Users are assumed to specify local masks that cover irregular components and parameters that determine the degree of restoration.The algorithm in this paper removes the defects based on the user-specific masks and parameters.Experiments have shown that the proposed methods can effectively remove redundant protrusions and jaggy noise.

Surface Coating of NiTi Shape Memory Alloys with Calcium Phosphates by Dip-coating or Plasma-spraying-biological Characterization Examined by in vitro Testing Methods

The influence of different surface coatings of NiTi shape memory allays was examined using in vitro testing methods. Plates of superelastic nickel-titanium shape memory allay （ NiTi ） were coated with calcium phosphates （ hydroxyapatite ） by high-temperature plasma-spraying or by dip-coating. The biocompatibility was tested in vitro by cultivation of isolated human granulocytes and whole blood cells. As substrates, pure NiTi, plasma-spray-coated NiTi and dip-coated NiTi were used. Isolated granulocytes showed an increased adhesion to both calcium phosphate-coated NiTi samples. Compared to non-coated NiTi or dip-coated NiTi, the number of dead granulocytes adherent to plasma-sprayed surfaces was significantly increased （ p 〈 0.01 ）. Whether the d/f- ferences in apoptosis of granulocytes on dip-coated vs plasma-sprayed coatings observed are due to differences in material surface morphologies has to be analyzed in further studies. Because of the cellular interactions with the coating layers, h is likely that the results obtained are not caused by the underlying NiTi but due to the coating itself.

Electrochemical behavior of Cu-Zn-Al shape memory alloy after surface modification by electroless plated Ni-P

The electrochemical behavior of Cu-Zn-Al shape memory alloy (SMA) with andwithout electroless plated Ni-P was investigated by electrochemical methods, in artificial Tyrode'ssolution. The results showed that Cu-Zn-Al SMA engendered dezincification corrosion in Tyrode'ssolution. The anodic active current densities as well as electrochemical dissolution sensitivity ofthe electroless plated Ni-P Cu-Zn-Al SMA increased with NaCl concentration rising, pH of solutiondecreasing and environmental temperature uprising. X-ray diffraction analysis indicated that aftersurface modification by electroless plated Ni-P, an amorphous plated film formed on the surface ofCu-Zn-Al SMA. This film can effectively isolate matrix metal from corrosion media and significantlyimprove the electrochemical property of Cu-Zn-Al SMA in artificial Tyrode's solution.

Surface properties of nitrogen-ion-implanted TiNi shape memory alloy

X-ray diffraction （XRD）, auger electron spectroscopy （AES）, and X-ray photoelectron spectroscopy （XPS） were used to characterize the surface properties of the N^ ＋-ion-implanted TiNi alloy. There is a high nitrogen content region at the outermost surface of the N^＋-ion-implanted TiNi alloy. The detected nitrogen exists mainly in the form of TiN. Small amounts of Ti305 and TiO2 also exist on the surface of the N^＋-ion-implanted TiNi sample. The modified layer of the N^＋-ion-implanted sample can work as an obstacle layer of the nickel＇s dissolution, which obstructs Ni dissolving from the TiNi surface effectively.

DIAGONAL POINT BY POINT SURFACE DEVELOPMENT METHOD BASED ON NURBS SURFACE FOR BLANK SHAPE ESTIMATION OFCOVER PANEL

According to the characteristics of a complex cover panel, its geometry shape is described by the NURBS surface with great description capability. With the reference to the surface classification determined by Gauss curvature, the proportion of the mid-surface area between before and after being developed is derived from the displacement variation of the mid-surface in the normal vector direction of the sheet metal during the sheet metal forming process. Hereby, based on the curve development theory in differential geometry, a novel diagonal point by point surface development method is put forward to estimate a complex cover panel＇s blank contour efficiently. By comparing the sample＇s development result of diagonal point by point surface development method with that of available one-step method, the validity of the proposed surface development method is verified.

Improved shape hardening function for bounding surface model for cohesive soils

A shape hardening function is developed that improves the predictive capabilities of the generalized bounding surface model for cohesive soils, especially when applied to overconsolidated specimens. This improvement is realized without any changes to the simple elliptical shape of the bounding surface, and actually reduces the number of parameters associated with the model by one.

A Subdivision-Based Combined Shape and Topology Optimization in Acoustics

We propose a combined shape and topology optimization approach in this research for 3D acoustics by using the isogeometric boundary element method with subdivision surfaces.The existing structural optimization methods mainly contain shape and topology schemes,with the former changing the surface geometric profile of the structure and the latter changing thematerial distribution topology or hole topology of the structure.In the present acoustic performance optimization,the coordinates of the control points in the subdivision surfaces fine mesh are selected as the shape design parameters of the structure,the artificial density of the sound absorbing material covered on the structure surface is set as the topology design parameter,and the combined topology and shape optimization approach is established through the sound field analysis of the subdivision surfaces boundary element method as a bridge.The topology and shape sensitivities of the approach are calculated using the adjoint variable method,which ensures the efficiency of the optimization.The geometric jaggedness and material distribution discontinuities that appear in the optimization process are overcome to a certain degree by the multiresolution method and solid isotropic material with penalization.Numerical examples are given to validate the effectiveness of the presented optimization approach.

Study on extracting method of single slope surface shape based on DEM:taking Wanzhou district of three gorges reservoir area as example

This paper focused on the extracting method of single slope shape. Applying the software of ARCGIS 9.0, DEM (digital elevation model) was established. From the DEM, topographic characters, including valleys and ridges were extracted. Some valley lines were extended in order to intersect with the ridges nearby. All slope were divided into different slope surface, which enclosed by valleys and ridges. And the slope surface shapes were defined three types, Line Slope, Upper-concave and lower-convex slope, Upper-convex and lower-concave slope, according to their functions. And the judge formula of single slope surface shape was brought forward. Taking Wanzhou District as test area, it indicates that auto-extracting method of single slope surface shape has high precision relatively. This study can provide references to the studies of region geological disasters prevention and cure.

A new method of fast measuring surface tension of melt cast iron and its application in graphite shape identification

Surface tension is one of important physical features of melt alloy. Many properties of melt alloy, such as graphite shape of cast iron and modified microstructure of aluminum alloy, can be evaluated by means of surface tension. In order to evaluate and control the melt quality in-situ melting operation, the authors advanced a new method and developed an automatic device for fast measuring surface tension of melt alloy and applied it to the practice of rapid identifying graphite shape of cast iron. In this paper, the principle of fast measuring surface tension, the construction of the automatic measurement device and the examples of evaluating graphite shape of cast iron based on the new method and device are discussed.

Effects of H_2O_2 pretreatment on surface characteristics and bioactivity of NaOH-treated NiTi shape memory alloy

The effects of H2O2 pretreatment on the surface characteristics and bioactivity of NaOH-treated NiTi shape memory alloy(SMA)were investigated by scanning electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,Raman spectra,Fourier transform infrared spectroscopy as well as a simulated body fluid(SBF)soaking test.It is found that the H2O2 pretreatment can lead to the direct creation of more Ti—OH groups and the decrease in the amount of Ni2O3,Na2TiO3 and remnant NiTi phases on the surfaces of bioactive NiTi SMA prepared by NaOH treatment.As a result,the induction period of apatite formation is shortened by dispensing with the slow kinetic formation process of Ti—OH groups via an exchange of Na+ ions from Na2TiO3 phase with H3O+ ions in SBF,which indicates that the bioactivity of NaOH-treated NiTi SMA can be further improved by the H2O2 pretreatment.

Method for predicting surface subsidence under excavating non-bedded shape room

The surface subsidence is caused by underground constructing, mining and excessively pumping groundwater. And disastrous accidents on unexpected collapse and landslide along bed plane probably occurred. Based on the stochastic medium theory and the methods for predicting ground point’s movements and deformations in any direction under folding structure strata and any shape rooms, the basic factors in varied geology and excavating were comprehensively analyzed. The formulas for predicting ground point’s movements and deformations were derived under excavating underground non-bedded shape rooms. Because the formulas for predicting surface subsidence can’t be integrated, the numerical integral method and the computer technique were adopted to calculate the values of integral equations.