Measuring the nuclear charge of fission fragments using a large ionization chamber—part of the double-arm time-of-flight spectrometer

Identification of decay products is a relevant task in studying rare collinear decays of low excited heavy nuclei. A technique for measuring the nuclear charge of decay products detected by a wide-aperture ionization chamber—a part of the double-arm time-of-flight spectrometer—is described. Two versions of nuclear charge calibration using data of the reaction ²³⁵U(n _th, f) have been developed to determine the charge of the decay products. Testing with simulation data shows that the use of charge parameterization based on the Bohr-Willer empirical equation in the calibration procedure makes it possible to determine the nuclear charge of the fission fragments over a wide energy range. The charges of light ions from He to C, predicted on the basis of this approach, appear to be overestimated by two charge units.     

Discrimination of particles by the scintillation pulse shape (in the electron energy range of 0.5–4.0 MeV) using the zero-crossing method

The ratios of the fast to slow components of scintillation pulses produced by neutrons and γ rays have been calculated on the basis of experimental data for several energies in the range of 0.5-4.0 MeV of the electron equivalent. The procedure for discriminating between neutrons and γ rays by measuring the zero-crossing time of a bipolar pulse formed by RC circuits has been simulated for organic scintillators using the Monte Carlo method in the range of 0.012-4.000 MeV of the electron equivalent. It is shown that pulse shape discrimination of particles based on the zero-crossing technique allows rejection of γ-ray background down to a level of 10-4 at particle energies of >100 keV of the electron equivalent (for energies of <50 keV, the γ-ray background is suppressed to a level of 10^-1- 10^-2 and this technique becomes ineffective in principle).     

Measuring the asymmetry of the longitudinal charge distribution in an electron bunch on the ВЭПП-4М collider

A method for measuring the asymmetry of the longitudinal charge distribution in an electron bunch of the ВЭПП-4М collider by an electron beam probe is proposed. The operating principle of the electron beam probe and the measuring technique are described. Interaction between the testing beam and an asymmetric relativistic bunch is simulated, and the asymmetry of the electron bunch on the ВЭПП-4 collider is measured. The main components of the error in measuring the asymmetry are determined.     

On “parallel” illumination in the transmission electron microscope

It has been generally assumed that, in a transmission electron microscope, there exists some combination of lens excitations that will yield almost parallel illumination over a large area of the sample. This assumption is incorrect, when the objective is an immersion lens, due to the beam rotation in the magnetic field. The lack of parallelism is outside the control of the operator and is proportional to the diameter of the illuminated area. It has been measured, in a typical case, as 0.4 mrad/μm, a value that agrees well with calculation. This effect is large and needs to be taken into account when using techniques where parallel illumination is desired.     

A note on “Selection of cutting parameters in side milling operation using graph theory and matrix approach”

Determination of optimal cutting parameters is one of the vital modules in process planning of parts since economy of machining operations plays an important role in increasing productivity and competitiveness. Recently, Gadakh and Shinde (Int J Adv Manuf Technol 2011) presented a graph theory and matrix approach (GTMA) and few other multiple attribute decision making (MADM) methods for selection of cutting parameters in side milling operation in their paper “Selection of cutting parameters in side milling operation using graph theory and matrix approach” Gadakh and Shinde (Int J Adv Manuf Technol DOI 10.1007/S00170-011-3256-Z, 2011). The authors had presented the experimental results of Chiang-Kao and Lu (Int J Adv Manuf Technol 34:440–447, 2007) to demonstrate the proposed methods. However, the systematic procedures of GTMA and the other MADM methods were already reported exhaustively by Rao (2007), and Gadakh and Shinde (Int J Adv Manuf Technol 2011) had reproduced the related contents. Many computational and fundamental mistakes were also present in their work. Furthermore, the authors had presented the incorrect values of metal removal rate (MRR) and these values were different from the values presented by Chiang-Kao and Lu (Int J Adv Manuf Technol 34:440–447, 2007). This note discusses these mistakes and presents the correct approaches and the results.     

Investigating Cases of “Abnormal” Attenuation of Ultrasonic Oscillations in Blanks of Nickel Heat-Resistant Alloys

Russian Journal of Nondestructive Testing - During ultrasonic nondestructive testing of several stamped forgings made of nickel heat-resistant alloys of two grades, we discovered a new phenomenon...     

The parameters measurement of air–water two phase flow using the electrical resistance tomography (ERT) technique in a bubble column

The air–water two-phase flow is investigated in a bubble column with a height of 2 m and a diameter of 0.282 m by using the Electrical Resistance Tomography (ERT) technique. The flow characterization are measured by applying ERT sensors of three vertical sections with superficial gas velocities in the range 0.027–0.156 m/s. Based on the cross-correlation technique and dynamic gas disengagement (DGD) theory, the bubble Saunter diameters are obtained and the local axial velocity about two phases flow can be calculated. The results show that with increased gas superficial velocity the distribution of bubble size is gradually widespread. Moreover, the local velocity of gas bubble swarm has a center peak distribution with increased gas superficial velocity.     

Analysis of guide modes in vertical hot ring rolling and their effects on the ring’s dimensional precision using FE method

In the vertical hot ring rolling (VHRR) process, roundness, outer radius, and width spread are three important indexes to the formed ring’s dimensional precision. In this paper, features of the guide modes of the VHRR process, such as single fixed guide mode (SFGM) and single follow-up guide mode (SFUGM), are analyzed to investigate their effects on the ring’s dimensional precision. The geometrical models of all the guide modes are then established and reliable three-dimensional coupled thermal-mechanical elastic-plastic FE models of the VHRR process are developed in ABAQUS/Explicit. Some key technologies, such as the guide roller’s motion control, are reasonably dealt with. The research results show that: (1) The roundness of the rings rolled by SFUGM is obviously superior to that of the ring rolled by SFGM. (2) With the same feed amount, the outer radius of the ring rolled by SFGM is always larger than that of the rings rolled by SFUGM. (3) During the rolling process of the ring rolled by SFGM, severe eccentricity will exist at the ring’s center, which is not obvious in the rolling process of the ring rolled by SFUGM. (4) The average value of width spread of the ring rolled by SFGM is slightly larger than that of the rings rolled by SFUGM. The research results can yield an understanding of some phenomena in the VHRR process. The modeling methods presented in this paper have general significance in the study of the VHRR process of the ring with complex profile.     

Erratum to “Prediction of fracture parameters of circumferential throughwall cracks in the interface between an elbow and a pipe under internal pressure”

Journal of Mechanical Science and Technology - There are two corrections to make to the original article. Firstly, Table 2 in the original article, was erroneously given. The Table 2 should read as...     

Visualization of “cracks” in steel using ferrite-garnet magneto-optical films with easy-plane anisotropy

Results of nondestructive testing of “cracks” in standard steel samples using magneto-optical ferrite-garnet films with the easy-plane anisotropy are given.     

Concerning one specific task of assembly in the automatic packing lines of the “Forming-Pre-Packing-Sealing-Cutting” type

By the example of the automatic line for packing of the food products, the task of automatic assembly of the components located on separate carrier tapes is reviewed. The methods to solve this task are described and their theoretical and experimental grounds are given. Special attention is paid to the analysis of the automatic assembly method based on the controlled change of the step of the tape carrier supply as the least sensitive to the mechanical properties of the carrier tapes. The characteristics of this method are estimated by means of the simulation model.     

Influence cutting parameters on the surface quality and corrosion behavior of Ti–6Al–4V alloy in synthetic body environment (SBF) using Response Surface Method

Most of the global manufacturing of titanium alloys is related to produce biphasic structures with grains alpha and beta. The development of modern applications of titanium alloy is a great challenge due to the chemical composition of Ti–6Al–4V alloy and the complexity of the manufacturing technology. This study proposed an optimal investigation of the variation of cutting speed, feed rate, and depth of cut in the turning of Ti–6Al–4V alloy on surface roughness, cutting efforts, and corrosion resistance. Response Surface Method has been established to optimize and model the responses mathematically. The adequacy of the models and a significant contribution of parameters were determined by analysis of variance (ANOVA). The biocompatibility of the machined surface for different cutting parameters was evaluated by the electrochemical polarization in simulated body fluids (SBF). Furthermore, desirability function analysis was used to determine the optimal values for surface quality, the turning force, and the passivation rate. It was clearly noticed that the multi-responses of the desirability function improved the machine process. The feed rate and depth of cut were the most relevant factors to minimize surface roughness and the turning forces. Moreover, the experimental results showed that the corrosion behavior was strongly related to minimal surface roughness. Finally, the optimization reduced the surface roughness Ra and Rz in 5.5% and 11.9%, respectively and increased the corrosion resistance in 18.8%.     

Practical applications of the “energy–triaxiality” state relationship in metal cutting

Most of the energy spent on metal cutting is due to the unavoidable plastic deformation of the layer being removed during its transformation into the chip. Based on the new principle of metal cutting being a purposeful fracture process, the dominant parameter that controls this process in orthogonal metal cutting (OMC) is the triaxiality state. Therefore, the chip triaxiality state in the deformation zone can be correlated to the energy of the unwanted plastic deformation for a particular cutting configuration. This article investigates this type of correlation by changing the cutting tool geometry. A series of finite element (FE) simulations were performed for various tool rake angles shows a strong relationship between the stress triaxiality state parameter in the deformation zone and the required cutting force components.