一类过程摄动系统的无阻塞鲁棒性

使用参数Dioid模块网络法,把含大量摄动参数的在普通极大代数意义下非线性状态空间模型在参数Dioid意义下线性化,在此基础上研究一类过程摄动系统的无阻塞鲁棒性.给出了有限缓冲串行生产系统在没有缓冲器下无阻塞的充要条件和充分条件.     

全同超形变带转动惯量的粒子数守恒计算

利用推转壳模型的粒子数守恒方法计算了超形变(SD)转动带¹⁹²Hg和¹⁹⁴Hg(1,2,3)的带首转动惯量.分析了带首附近的组态结构及带首转动惯量随对力强度的变化.带首转动惯量之差δJ₀对对力强度十分敏感,而对Nilsson能级参数K、μ及形变参数并不敏感.对力及堵塞效应是造成带首转动惯量差别的主要因素.但与正常形变核相比,对力强度似有较大程度减弱.     

Fe3O4/葡聚糖/抗体磁性纳米生物探针的制备和层析检测

在免疫检测中 ,经常利用一些具有特殊物理化学性质的标记物对抗体 (或抗原 )进行偶联标记 ,在抗体与抗原识别后 ,通过对标记物的定性和定量检测而达到对抗原 (或抗体 )检测的目的 .传统的免疫标记物包括放射性同位素 [1] 、酶 [2 ] 、胶体金 [3] 和有机荧光染料分子 [4 ] 等 .近年来 ,随着纳米技术的发展 ,半导体荧光纳米晶 [5,6 ] 和磁性纳米晶 [7] 在免疫检测方面受到了广泛关注 .磁性纳米晶性能稳定 ,较易制备 ,可与多种分子复合使粒子表面功能化 ,并且由于磁纳米晶具有超顺磁性 ,为样品的分离、富集和提纯提供了很大方便 .这些优点使它…     

The blocking and structural properties of a Schiff base self-assembled monolayer on the surface of Au(111)

Electrochemistry and in situ electrochemical scanning tunneling microscopy (STM) were used to study the blocking and structural properties of Shiff base V-ape-V self-assembled monolayers (SAMs) on the surface of Au(111) in perchloric acid solution. The complex-plane impedance plots for the SAM covered Au(111) electrodes, with the redox couple of Fe(CN)₆^4–/3– present in solution, exhibit arc shapes, revealing that the electrochemical kinetics were controlled by the electron-transfer step. For bare Au(111), the electrode process was mass transport limited. The molecules adsorb on Au(111) with a flat-lying orientation and form a long-range well-defined adlayer. A new structure of was observed in the double-layer potential region. A structural model is proposed to interpret the molecular registry with Au(111) substrate.     

Two-worker blocking congestion model with walk speed m in a no-passing circular passage system

This paper introduces a blocking model and closed-form expression of two workers traveling with walk speed m (m = integer) in a no-passing circular-passage system of n stations and assuming n = m + 2, 2m + 2, …. We develop a Discrete-Timed Markov Chain (DTMC) model to capture the workers’ changes of walk, pick, and blocked states, and quantify the throughput loss from blocking congestion by deriving a steady state probability in a closed-form expression. We validate the model with a simulation study. Additional simulation comparisons show that the proposed throughput model gives a good approximation of a general-sized system of n stations (i.e., n > 2), a practical walk speed system of real number m (i.e., m ? 1), and a bucket brigade order picking application.     

Microstructure and Magnetic Properties of Carbon‐Coated Nanoparticles

Abstract

In the present work, microstructure and superparamagnetic properties of two types of carbon‐coated magnetic Ni and Fe nanoparticles [Ni(C) and Fe(C)] are reviewed. High‐resolution transmission electron microscopy (HRTEM), electron diffraction (SAED), and x‐ray diffraction (XRD) analyses have been used to reveal the distinct structural morphologies of Ni and Fe nanoparticles. Moreover, novel carbon‐coated Ni nanoparticle assemblies offer us great opportunities for studying the mechanism of superparamagnetism in particle assemblies. Magnetization measurements [M(T) and M(H) curves] for assemblies of Ni nanoparticles indicate that modified superparamagnetic properties at T > T _B, have been found in the assemblies of Ni(C) particles. The blocking temperature, T _B, is determined to be near 115K under a certain applied field. Above T _B, the magnetization M(H, T) can be described by the classical Langevin function L using the relation, M/M _s (T = 0) = coth (μH/kT) ? kT/μH. It is suggested that these assemblies of carbon‐coated Ni nanoparticles have typical single‐domain, field‐dependent superparamagnetic relaxation properties. Finally, Mössbauer spectra and hyperfine magnetic fields at room temperature for the assemblies of Fe(C) nanoparticles confirm their distinct nanophases that were detected by structural analysis. Modified superparamagnetic relaxation is observed in the assemblies of Fe(C) nanoparticles, which is attributed to the nanocrystalline nature of the carbon‐coated nanoparticles.     

Roles of blocking layer and anode bias in processes of impurity-band transition and transport for GaAs-based blocked-impurity-band detectors

Recently, GaAs-based BIB detector has attracted a lot of attention in the area of THz photovoltaic detection due to potential application values in security check and drug inspection. However, the physical mechanisms involving in carrier transition and transport are still unclear due to the poor material quality and immature processing technique. In this paper, the dark current and THz response characteristics have thus been numerically studied for GaAs-based blocked-impurity-band (BIB) detectors. The key parameters and physical models are constructed by simultaneously considering carrier freeze-out and impurity-band broadening effects. Roles of blocking layer and anode bias in processes of impurity-band transition and transport are intensively investigated, and the results can be well explained by numerical models. It is demonstrated that the effective electric field for the detector is only located in the absorbing layer, and can determine to a large extent the magnitude of the dark current and THz response. While the blocking layer not only can suppress dark current but also can attenuate responsivity due to its electric-field modulation effect.     

Viscoelastic wave propagation in the viscoelastic single walled carbon nanotubes based on nonlocal strain gradient theory

In this paper, the viscoelastic wave propagation in an embedded viscoelastic single-walled carbon nanotube (SWCNT) is studied based on the nonlocal strain gradient theory. The characteristic equation for the viscoelastic wave in SWCNTs is derived. The emphasis is placed on the influence of the tube diameter on the viscoelastic wave dispersion. A blocking diameter is observed, above which the wave could not propagate in SWCNTs. The results show that the blocking diameter is greatly dependent on the damping coefficient, the nonlocal and the strain gradient length scale parameters, as well as the Winkler modulus of the surrounding elastic medium. These findings may provide a prospective application of SWCNTs in nanodevices and nanocomposites.     

The least square nucleolus is a general nucleolus

This short note proves that the least square nucleolus (Ruiz et al. (1996)) and the lexicographical solution (Sakawa and Nishizaki (1994)) select the same imputation in each game with nonempty imputation set. As a consequence the least square nucleolus is a general nucleolus (Maschler et al. (1992)). Received: December 1998/Revised version: July 1999