Investigation of the thermo-mechanical properties of single-walled carbon nanotubes based on the temperature-related higher order Cauchy-Born rule

In the present study, a nanoscale quasi-continuum constitutive model for predicting the thermal-mechanical properties of single-walled carbon nanotubes (SWCNTs) and graphene sheet is established based on the interatomic potential and the temperature-related higher order Cauchy-Born rule. Helmholtz free energy is used as the corresponding thermodynamic potential. It is a function of some temperature-dependent lattice parameters that can be determined through an energy minimization process. As an application of the proposed quasi-continuum model, temperature dependency and curvature effect of the specific heat, the coefficient of thermal expansion (CTE) and the Young’s modulus of SWCNTs are investigated systematically. Numerical results obtained show the effectiveness of the proposed constitutive model.     

坚持“依法治国”与“以德治国”相结合,进一步巩固党的领导

通过对“以德治国”提出的重要意义 ,“以德治国”是“依法治国”的重要补充 ,以及“德治”和“法治”的关系等几方面进行的讨论 ,提出为进一步巩固党的领导 ,实施“以德治国”中官德修养的主要途径和工作方法     

On the backlog-sequencing decision for extending the applicability of ConWIP to high-variety contexts: an assessment by simulation

Constant Work-in-Process (ConWIP) is a card-based control system that was developed for simple flow shops – a lack of load-balancing capabilities hinders its application to more complex shops. In contrast, load balancing is an integral part of Workload Control, a production planning and control concept developed for high-variety environments. One means of load balancing evident in the Workload Control literature is through the use of a capacity slack-based backlog-sequencing rule. This study therefore investigates the potential of the backlog-sequencing decision to improve load balancing in the context of ConWIP, thereby making it suitable for more complex, high-variety environments. Using simulation, we demonstrate that: (i) the choice of backlog-sequencing rule significantly impacts throughput times and tardiness-related performance measures; and (ii) capacity slack-based sequencing rules achieve significant performance improvements over ‘classical’ ConWIP backlog-sequencing rules. These results significantly extend the applicability of ConWIP. Results from the Workload Control literature however do not directly translate across to ConWIP. The simplified release procedure of ConWIP makes backlog-sequencing based on planned release dates dysfunctional. This negatively impacts the performance of modified capacity slack-based sequencing rules that were recently shown to be the best choice for Workload Control.     

Advisability of revising the rounding-off rule for measurement results

Specific examples and theoretical reasons are given to prove the advisability of revising the GSI rules for rounding-off the results of measurements. This is especially important in settlements between suppliers and consumers of large consignments of products, primarily relating to energy supply.Translated from Izmeritelnaya Tekhnika, No. 11, pp. 56–58, November, 2004.     

水平尺专用检台校准装置设计

文章对水平尺专用检台校准装置的设计进行了较为详细的论述。该装置通过对 90°、 45°角的合理组合 ,并采取了正确的检测方法 ,进行了校准不确定度的分析 ,其结果此装置的扩展不确定度为 0 3 6′ (置信概率p =99% ,k =3 )。     

光面爆破的岩石裂纹扩展规律研究

光面爆破是一种控制爆破技术,为了实现更为精确的控制爆破效果,需要对光面爆破的岩石裂纹扩展规律进行研究。在光面爆破的初始裂纹产生阶段,利用数值模拟的方法,对光面爆破的弹性力学简化模型进行分析,得到了初始裂纹的起裂点位置以及初始裂纹长度。在爆轰气体驱动下,初始裂纹二次扩展。从裂纹扩展的能量角度,分析了裂纹扩展速度与裂纹长度的定量关系。基于断裂力学对裂纹二次扩展条件和二次扩展范围进行理论分析,定量描述了裂纹二次扩展长度与孔壁压力的关系。最后,在对光面爆破致裂机理认知的基础上,提出光面爆破中装药不耦合系数、炮孔间距、光面层厚度等参数的计算方法。     

Nanocrystal Model for Liquid Metals and Amorphous Metals

A nanocrystal model for liquid metals and amorphous metals has been developed. With the nanocrystal model, the broadening peak profiles (BPPs) of Cu, Al, Al₆₅Cu₂₀Fe₁₅ alloy, Cu₇₀Ni₃₀ alloy and Fe₅₀Si₅₀ alloy were gained by broadening the X-ray diffraction (XRD) peaks of a crystal lattice. By comparing the BPPs with the XRD intensity curves measured on the liquid metals, it is found that the BPPs are closely in agreement with the XRD intensity curves, respectively, except the Fe₅₀Si₅₀ alloy. Therefore, the nanocrystal model can be used to determine if the atomic cluster structure of the liquid metal is similar to the structure of its crystal lattice.     

基于非关联流动法则的滑移线场及上限法研究

当前岩土材料的滑移线场理论及上限法中都广泛采用经典塑性理论中的关联流动法则,由此得出应力特征线与速度滑移线一致的结论。而试验得知,岩土材料并不服从关联流动法则,因而应力特征线与速度滑移线不可能重合。文章分析了基于关联流动法则的滑移线场及上限法中存在的问题,根据广义塑性理论推导了基于非关联流动法则的滑移线场及上限法,消除了现行滑移线场理论及上限法理论中的种种矛盾。     

On the 80/20 rule

In a recent paper¹ Burrell shows that libraries with lower average borrowings tend to require a larger proportion of their collections to account for 80% of the borrowings, than those with higher average borrowings. In that study, the underlying frequency distribution was a negative binomial. We are dealing with a case when the underlying distribution is of Lotka type. It is also shown that the 80/20-effect is much stronger in this case.     

Surface stress effects on the critical buckling strains of silicon nanowires

The objective of this paper is to quantify how nanoscale surface stresses impact the critical buckling strains of silicon nanowires. These insights are gained by using nonlinear finite element calculations based upon a multiscale, finite deformation constitutive model that incorporates nanoscale surface stress and surface elastic effects to study the buckling behavior of silicon nanowires that have cross sectional dimensions between 10 and 25 nm under axial compressive loading. The key finding is that, in contrast to existing surface elasticity solutions, the critical buckling strains are found to show little deviation from the classical bulk Euler solution. The present results suggest that accounting for axial strain relaxation due to surface stresses may be necessary to improve the accuracy and predictive capability of analytic linear surface elastic theories.     

Further MN rule in thermally activated a.c. conduction of Se-Te-Sb chalcogenide glasses

Temperature and frequency dependence of a.c. conductivity have been studied in glassy Se₇₀Te_30−xSb_x (4 ≤ x ≤ 10) alloys. The observation of Further Meyer-Neldel rule in case of a.c. conductivity is reported. The observation of the correlation between Meyer-Neldel pre-factor σ₀₀ and Meyer-Neldel energy is explained by multiple excitations stimulated by optical phonon energy as described by Yelon and Movaghar.     

不同储存形态玉米水分的变化规律

本文阐述了不同储存形态玉米水分的变化幅度。既包装玉米大于囤积玉米：囤积大于散装玉米：穗藏大于粒藏玉米：露天储存玉米大于仓内储藏玉米。无论哪种储存形态的玉米,其水分的变化幅度都遵循一个规律：上层玉米（接触空气多）水分的变化,一般大于下层,了解这一规律对安全储存玉米具有实际指导意义。     

Multiparametric sufficient criterion of quasi-brittle fracture for complicated stress state

Behaviour of an atomic structure in the vicinity of the crack tip is simulated. Buckling and postbuckling deformation of three- and four-atomic cells at generalized tension is studied. A discrete-integral fracture criterion is proposed for normal rupture cracks when stress fields have a singular component, vectors of fields of stresses and deformations being collinear. When formulating the proposed criterion, we used the new rank of solutions, which differ from solutions applied in formulating the classical sufficient fracture criterion, in conformity with Novozhilov’s hybrid model. The proposed criterion permits limiting passage to necessary criterion when energetic characteristics of postbuckling deformation of cells can be neglected within the limit. Values of critical loads obtained in conformity with the sufficient criterion essentially differ from those obtained in conformity with the necessary criterion.     

Ion channeling study of epitaxy of iron based Heusler alloy films on Ge(111)

We have investigated perfection of atomic rows on iron-based Heusler alloy films on Ge(111) planes by using ion channeling technique in order to find the dominant factors for the perfection. Fe₃Si/Ge(111) and Fe₂CoSi/Ge(111) have a high quality of atomic rows at the heterointerface like that of perfect crystals. Fe_3−xMn_xSi/Ge(111) (x = 0.84, 0.72 and 0.36) interfaces have imperfection of atomic rows which may be controlled by both the lattice mismatch with the Ge substrate and the Mn-Si pairs due to the site disorder in the film with the Mn content x > 0.75. Analysis of axial channeling parameters employed in this study is very useful for quantitative evaluation of perfection of atomic rows at the heterointerface.     

Electrical resistivity and deviation from matthiessen's rule in polycrystalline lead-doped tin

The results of measurements of the electrical resistivity, of lead-doped (weight concentrations: 0.001, 0.01, 0.1, and 1%) polycrystalline tin are presented. The experiments were performed using a comparative method with the aid of a tantalum thermomagnetic modulator applied as a null indicator. A nonlinear dependence of the residual resistivity on lead concentration was obtained. An anomalous character ofp(T) dependence was observed in the lowest-Pb concentration sample (0.001%). The deviation of the resistivity-temperature characteristics from Matthiessen's rule (DMR) was determined. The characteristics of the DMR do not show humps in the temperature range from 3.7 to 28 K.     

概念知识系统与概念信息粒格

在概念格的基础上给出了概念知识格以及概念信息粒格,讨论了概念信息粒之间的蕴含关系及由概念生成不确定规则的方法.给出了任意对象集和属性集构成概念信息粒的方法,以及迭代形成概念的方法,从而刻划出认知的逐步深化过程.     

Quadratic damage rule in random loading case

The simple mathematical structure of the quadratic damage rule (QDR) enables mathematical expression of the failure condition in the case of random loading. Random loading after modified rainflow analysis is considered as a random marked point process. Moments of the damage distribution can be expressed by use of ensemble averages. A condition for validity of the first damage moment solution is formulated. The QDR damage first moment solution involves failure predictions for both stationary and non‐stationary loadings. In these cases, final fracture conditions suitable for practical use are derived. QDR predicts fatigue lives that are always shorter than the linear damage rule (LDR) in the case of stationary loading with short interval of statistical dependence of random variables. QDR appears to be a suitable additional engineering tool for random loading fatigue life predictions considering loading sequence and loading level interactions.     

Energy band alignment at interfaces of semiconducting oxides: A review of experimental determination using photoelectron spectroscopy and comparison with theoretical predictions by the electron affinity rule, charge neutrality levels, and the common anion rule

The energy band alignment at interfaces of semiconducting oxides is of direct relevance for the electrical function of electronic devices made with such materials. The most important quantities of the interface determined by band alignment are the barrier heights for charge transport given by the Fermi level position at the interface and the band discontinuities. Different models for predicting energy band alignment are available in literature. These include the vacuum level alignment (electron affinity rule), branch point or charge neutrality level alignment governed by induced gap states, and an alignment based on the orbital contributions to the density of states (common anion rule). The energy band alignment at interfaces of conducting oxides, which have been experimentally determined using photoelectron spectroscopy with in situ sample preparation, are presented. The materials considered include transparent conducting oxides like In₂O₃, SnO₂, ZnO, and Cu₂O, dielectric and ferroelectric perovskites like (Ba,Sr)TiO₃ and Pb(Zr,Ti)O₃, and insulators like Al₂O₃. Interface formation with different contact partners including metals, conducting and insulating oxides are addressed. The discussion focuses on the energy band alignment between different oxides. A good estimate of the band alignment is derived by considering the density of states of the materials involved.     

Adaptive cumulative sum charts with the adaptive runs rule

Adaptive cumulative sum (ACUSUM) charts, which adjust the reference value dynamically based on estimated shift size, provide good performance in detecting a range of mean shifts. However, when the range is wide, ACUSUM may not perform well for small shifts over the range. An adaptive runs rule, which is motivated by the concept of supplementary runs rule, is proposed, in order to make control charts more sensitive to small mean shifts. The adaptive runs rule assigns scores to consecutive runs based on the estimated shift size of the mean. The ACUSUM chart is supplemented with the adaptive runs rule to enhance its sensitivity in detecting small mean shifts. The average run length performance of the ACUSUM chart with the adaptive runs rule is compared with those of cumulative sum and variants of adaptive charts including ACUSUM. The experimental results reveal that the ACUSUM chart with the adaptive runs rule achieves superior detection performance over a wide range of mean shifts.