锻造变形过程中孔洞缺陷闭合行为Q-Value法研究

以宽厚板支承辊锻造所用大型钢锭为研究对象,通过对模拟软件中用户子程序二次开发,运用Q-Value阈值法对大锻件内部孔洞缺陷在锻造变形过程中的闭合行为进行预测,从而极大简化了传统孔洞类缺陷变形的模拟思路,提高了模拟效率。

Characteristics of coda Q-value in the midnorthern part of Ningxia

On the basis of previous studies, this paper in studying the coda Q-valuc of near shocks, has proposed using the sampling depth to describe the effect of lapse time on the Q-value, and has investigated the dependence of coda wave of earthquakes on frequency and sampling depth. Analysis of digital seismograms recorded by the Yinchuan Telemetric Seismic Network, Ningxia, shows that not only the coda wave Q-value of shocks is strongly dependent on frequency but also its dependence on Samling depth cannot be neglected. In the commonly used formula that describes the dependence cbaracteristics of coda Q-value of endquakes, Q = Qof', the parameter Qo rises obviously whilc n drops when the sampling depth increases, and their changes can be fitted by linear relations. This paper has explained such a characteristic. Whether this characteristic exists universally needs to be verified by more study results because the genetic mechanism of coda wave of earthquakes is more complex.

Positive Q-Value Neutron Transfer Mediated Sub-Barrier Fusion Reactions

Positive Q-value neutron transfer mediated sub-barrier fusion reactions are studied with an empirical coupled channels model, which takes into account neutron rearrangement related only to the dynamical matching condition with no free parameters. Fusion cross sections of collision systems ^32S＋^90,94,96Zr are calculated and analyzed. Logarithmic residual enhancement （LRE） is proposed to evaluate the discrepancy between calculated results and experimental data. The experimental data can be described well with this model for the first time as a whole, while the LRE analysis shows that there are still theoretical systematic deviations.

论用球谐函数拟合地幔地震波品质因数Q值空间分布

本文引用S.J.Duda所导出的吸收特征时间t*与震中距离△的关系,由地震台网观测的地震波振幅A和周期T,求得观测的t0*,及t0*～△的关系函数,用以拟合不同周期范围地震波品质因数Q 值随深度的分布Q（h）,从而计算理论的t*,再由t*的残差δt*与δQ 的关系参照A.M.Dzjewonskj 拟合地幔地震波速度三维分布的方法运用球谐函数的关系拟合地幔地震波品质因数Q 值的三维空间分布。

A Study of Rock Magnetism of High-Grade Hematite Ores

Rock magnetism is useful in various applications. Hematite is one of the two most important carriers of magnetism in the natural world and its magnetic features were mostly studied through laboratory experiments using synthetic hematite samples. A gap exists between the magnetic behaviors of hematite contained in the natural rocks and ores and those of synthetic hematite samples. This paper presents the results of a rock magnetism study on the natural hematite ores from the Whaleback mine in the Hamersley Province in the northwest of Western Australia. It was found that high-grade hematite ores carry a much higher remanent magnetization than induced magnetization. Hematite ores with less than 0.1% magnetite appear to have an exponential correlation between the bulk susceptibility and hematite content in weight percentage, different from the commonly accepted linear relationship between the bulk susceptibility and hematite content obtained from synthetic hematite samples. The new knowledge gained from this study contributes to a better understanding of magnetic behaviors of hematite, particularly natural hematite, and hence applications to other relevant disciplines.

Reducing risk in long deep tunnels by using TBM and drill-and-blast methods in the same project-the hybrid solution

There are many examples of TBM tunnels through mountains, or in mountainous terrain, which have suffered the ultimate fate of abandonment, due to insufficient pre-investigation. Depth-of-drilling limitations are inevitable when depths approach or even exceed l or 2 km. Uncertainties about the geology, hydro-geology, rock stresses and rock strengths go hand-in-hand with deep or ultra-deep tunnels. Unfortunately, unexpected conditions tend to have a much bigger impact on TBM projects than on drill-and-blast projects. There are two obvious reasons. Firstly the circular excavation maximizes the tangential stress, making the relation to rock strength a higher source of potential risk. Secondly, the TBM may have been progressing fast enough to make probe-drilling seem to be unnecessary. If the stress-to-strength ratio becomes too high, or if faulted rock with high water pressure is unexpectedly encountered, the ＂unexpected events＂ may have a remarkable delaying effect on TBM. A simple equation explains this phenomenon, via the adverse local Q-value that links directly to utilization. One may witness dramatic reductions in utilization, meaning ultra-steep deceleration-of-the-TBM gradients in a log-log plot of advance rate versus time. Some delays can be avoided or reduced with new TBM designs, where belief in the need for probe-drilling and sometimes also pre-injection, have been fully appreciated. Drill-and-blast tunneling, inevitably involving numerous ＂probe-holes＂ prior to each advance, should be used instead, if investigations have been too limited. TBM should be used where there is lower cover and where more is known about the rock and structural conditions. The advantages of the superior speed of TBM may then be fully realized. Choosing TBM because a tunnel is very long increases risk due to the law of deceleration with increased length, especially if there is limited pre-investigation because of tunnel depth.

Research on overlapping structures and evolution properties of co-citation network

Purpose: This paper intends to explore methodologies and indicators for the analysis of overlapping structures and evolution properties in a co-citation network, and provide reference for overlapping structure analysis of other scientific networks.Design/methodology/approach: The Q-value variance is defined to achieve overlapping structures of different levels in the scientific networks. At the same time, analyses for time correlation variance and subject correlation variance are used to present the formation of overlapping structures in scientific networks. As a test, a co-citation network of highly cited papers on Molecular Biology & Genetics from Essential Science Indicator(ESI) is taken as an example for an empirical analysis.Findings: Our research showed that the Q-value variance is effective for achieving the desired overlapping structures. Meanwhile, the time correlation variance and subject correlation variance are equally useful for uncovering the evolution progress of scientific research, and the properties of overlapping structures in the research of co-citation network as well.Research limitations: In this paper, the theoretical analysis and verification of time and subject correlation variances are still at its initial stage. Further studies in this regard need to take actual evolution of research areas into consideration.Practical implications: Evolution properties of overlapping structures pave the way for overlapping and evolution analysis of disciplines or areas, this study is of practical value for the planning of scientific and technical innovation.Originality/value: This paper proposes an analytical method of time correlation variance and subject correlation variance based on the evolution properties of overlapping structures, which would provide the foundation for the evolution analysis of disciplines and interdisciplinary research.

Mass Measurement of ^(168)Dy by Heavy Ion Transfer Reaction

The mass of 168Dy is measured for the first time,using the two-proton pick-up reaction 170Er(18O,20Ne)at an 18O energy of 104 MeV.The products of the reaction are detected at the focal plane ofthe Q3D spectrometer.The mass excess of 168Dy is found to be -58.56±0.14 MeV.

Measurement of the Mass Excess of ^(158)Sm

A Q-value of —4.076±0.151 MeV has been determined for the two-proton transfer reaction160Gd(18O,20Ne)158Sm,which yields a first experimental measured value of —65.764±0.151 MeV forthe mass excess of 158Sm,the nucleus far from stability.The result is compared with current theoreticalpredictions.

New measurement of 4^(H)e and proton decays from resonant states in^(19)Ne

A^(6)Li(^(16)O,^(19)Ne^(∗))^(3)H multi-nucleon transfer-reaction experiment was performed to populate the highly excited states in^(19)Ne.The subsequent decay particles,^(4)He or protons from the^(19)Ne resonant states,were detected in coincidence with the recoil 3 H.The excitation-energy spectra of^(19)Ne were reconstructed using the detected proton or^(4)He and the deduced^(18)F or^(15)O data,respectively.A broad resonance at about 7.85 MeV(1/2^(+))was observed,with partial decay widths different from the previously reported values,which may have a significant impact on the destruction of 18 F in astrophysical processes.Several resonances up to very high excitation energies have been identified with a largeα-clustering strength,which confirm the formation of the cluster structure with a one-hole configuration in light nuclei and encourage further systematic studies of the cluster structure in^(19)Ne.

Preformation probability and kinematics of cluster emission yielding Pb-daughters

In the present study,the newly established preformation formula is applied for the first time to study the kinematics of the cluster emission from various radioactive nuclei,especially those that decay to the double shell closure^(208)Pb nucleus and its neighbors as daughters.The recently proposed universal cluster preformation formula has been established based on the concepts that underscore the influence of mass and charge asymmetry(η_(A)andη_(Z)),cluster mass A_(c),and the Q-value,paving the way to quantify the energy contribution during preformation as well as during the tunneling process separately.The cluster-daughter interaction potential is obtained by folding the relativistic mean-field(RMF)densities with the recently developed microscopic R3Y using the NL 3^(*)and the phenomenological M3Y NN potentials to compare their adaptability.The penetration probabilities are calculated from the WKB approximation.With the inclusion of the new preformation probability P_(0),the predicted half-lives of the R3Y and M3Y interactions are in good agreement with the experimental data.Furthermore,a careful inspection reflects slight differences in the decay half-lives,which arise from their respective barrier properties.The P_(0)for systems with double magic shell closure^(208)Pb daughter are found to be an order of≈10^(2)higher than those with neighboring Pb daughter nuclei.By exploring the contributions of the decay energy,the recoil effect of the daughter nucleus is evaluated,in contrast to several other conjectures.Thus,the centrality of the Q-value in the decay process is demonstrated and redefined within the preformed cluster-decay model.Additionally,we have introduced a simple and intuitive set of criteria that governs the estimation of recoil energy in the cluster radioactivity.

α-cluster decay from ^(24)Mg resonances produced in the ^(12)C(^(16)O,^(24)Mg)α reaction

A transfer reaction and cluster-decay experiment,12C(16O,24Mg→ α+20Ne)α, was performed at a beam energy of 96 MeV. Both recoil and decay α particles were detected in coincidence, allowing us to deduce the energymomentum of a20Ne fragment. A number of resonant states of24Mg were reconstructed up to an excitation energy of approximately 30 MeV. Owing to the experimentally achieved excellent resolutions of the Q-value and excitationenergy spectra, the relative decay widths for each resonant state in24Mg to various final states of20Ne were extracted, along with the total decay width. The obtained results provide good testing ground for theoretical descriptions of multiple clustering configurations in24Mg.

Evaluation of modified adaptive k-means segmentation algorithm

Segmentation is the act of partitioning an image into different regions by creating boundaries between regions.k-means image segmentation is the simplest prevalent approach.However,the segmentation quality is contingent on the initial parameters(the cluster centers and their number).In this paper,a convolution-based modified adaptive k-means(MAKM)approach is proposed and evaluated using images collected from different sources(MATLAB,Berkeley image database,VOC2012,BGH,MIAS,and MRI).The evaluation shows that the proposed algorithm is superior to k-means++,fuzzy c-means,histogrambased k-means,and subtractive k-means algorithms in terms of image segmentation quality(Q-value),computational cost,and RMSE.The proposed algorithm was also compared to state-of-the-art learning-based methods in terms of IoU and MIoU;it achieved a higher MIoU value.

Self-consistent analysis of sub-barrier fusion enhancement effect in Ca+Ca and Ni+Ni

The fusion dynamic mechanism of heavy ions at energies near the Coulomb barrier is complicated and still not very clear up to now. Accordingly, a self-consistent method based on the CCFULL calculations has been developed and applied for an ongoing study of the effect of the positive Q-value neutron transfer （PQNT） channels in this work. The typical experimental fusion data of Ca ＋ Ca and Ni ＋ Ni is analyzed within the unified calculation scheme. The PQNT effect in near-barrier fusion is further confirmed based on the self-consistent analysis and extracted quantitatively.