Guest Editors' Introduction: Attacking Functional Verification through Hybrid Techniques

Hybrid techniques are effective for exploring interesting corner cases, coverage holes, invariant variations, and so forth, in the general area of directed functional validation. However, despite the emergence of several effective hybrid validation techniques, several questions still remain. The five articles in this special issue help explain some of the different facets of this area.     

High-temperature sensible-heat storage options

Alkali-metal carbonate salts meet the requirements for high-temperature solar central receiver systems, but because of their corrosiveness they present special problems in the design of storage tanks. In order to reduce corrosion and temperature sufficiently to retain strength in the storage containing wall, internal and thermal insulation is required. We present design options and operation criteria for sensible-heat, molten-salt storage with internal insulation.     

为了满足使用者需求而设计——上海地铁研究·使用者需求

在上海地铁研究中,我们发现了许多使用者的不满。这些不满来自于设计师对使用者的缺乏了解和缺乏关注。通过对上海地铁真实的使用者、真实的地点和真实的时间的调研,我们分析出25项上海地铁使用者的需求。并提出希望设计师能够从这些使用者的需求出发,去作为使用者带来良好体验的设计。     

吸入短寿命氡子体动物肺组织剂量与体重关系的探讨

本文介绍吸入短寿命氡子体的不同种动物肺组织吸收剂量与体重的关系。实验结果表明,吸收剂量随体重的增加而减小。     

巯基棉预浓集—中子活化法测定水泥及其浸出水中的微量汞

在不同酸度下巯基棉可以从溶液中富集和分离Au、As、Ag、Br、Cu、Ca Co、InHg、Ni、Se、Sb、Sn、Pb、W、Fe和In等30多种元素。由于用巯基棉吸附待测元素后不必洗脱,因此大大提高了富集能力,可用于海水、地下水、地表水及工业废水中一些元素的测量。本文用巯基棉富集后进行中子活化分析测定水泥及其浸出水中的汞。     

N-Type Field-Effect Transistors Using Multiple Mg-Doped ZnO Nanorods

Nanorod field-effect transistors (FETs) that use multiple Mg-doped ZnO nanorods and a SiO₂ gate insulator were fabricated and characterized. The use of multiple nanorods provides higher on-currents without significant degradation in threshold voltage shift and subthreshold slopes. It has been observed that the on-currents of the multiple ZnO nanorod FETs increase approximately linearly with the number of nanorods, with on-currents of ~1 muA per nanorod and little change in off-current (~4times10^-12). The subthreshold slopes and on-off ratios typically improve as the number of nanorods within the device channel is increased, reflecting good uniformity of properties from nanorod to nanorod. It is expected that Mg dopants contribute to high n-type semiconductor characteristics during ZnO nanorod growth. For comparison, nonintentionally doped ZnO nanorod FETs are fabricated, and show low conductivity to compare with Mg-doped ZnO nanorods. In addition, temperature-dependent current-voltage characteristics of single ZnO nanorod FETs indicate that the activation energy of the drain current is very low (0.05-0.16 eV) at gate voltages both above and below threshold     

Optical properties of Nd-doped Ca3(VO4)2 single crystal fiber

Optical absorption and photoluminescence of Ca₃(VO₄)₂ single crystal grown by a floating-zone technique and containing Nd³⁺ ions were investigated. High absorption coefficients and broadening of most absorption bands are present at 300 K, while substructures in some of the same bands can be evidenced at 12 K. Most features of measured spectra are characteristic of random occupation of more than a single Ca²⁺ site by the Nd³⁺ ion and of distortions provoked by different charge compensation mechanisms involving oxygen vacancies promotion in the crystal lattice. Nd³⁺ optical properties were studied by using the Judd-Ofelt theory to calculate the spectral parameters relevant for laser applications.     

Design and analysis of a plug-in robust compensator: an application to indirect-field-oriented-control induction machine drives

It is well known that the system performance for an indirect-field-oriented-control induction motor drive degrades under the variation of rotor resistance and in the presence of external load torque. In this paper, a plug-in robust compensator for speed and position control enhancement of an indirect-field-oriented-control induction machine drive is developed. In the case where a controller for the induction machine already exists or is in operation with satisfactory nominal tracking performance, this plug-in compensator, designed using the H/sub /spl infin// loop-shaping techniques, can be plugged into the existing controller without affecting the already satisfactory nominal tracking performance of the existing closed-loop system but with the capability to improve the system performance under plant parameter variations and in the presence of external disturbances. Simulation and experimental results are given to validate the proposed plug-in robust compensator.     

Decreasing miscibility with greater heterogeneity in ternary polymer blend: poly(cyclohexyl methacrylate), poly(α‐methyl styrene) and poly(4‐methyl styrene)

A ternary blend system comprising poly(cyclohexyl methacrylate) (PCHMA), poly(α‐methyl styrene) (PαMS) and poly(4‐methyl styrene) (P4MS) was investigated by thermal analysis, optical and scanning electron microscopy. Ternary phase behaviour was compared with the behaviour for the three constituent binary pairs. This study showed that the ternary blends of PCHMA/PαMS/P4MS in most compositions were miscible, with an apparent glass transition temperature (T_g) and distinct cloud‐point transitions, which were located at lower temperatures than their binary counterparts. However, in a closed‐loop range of compositions roughly near the centre of the triangular phase diagram, some ternary blends displayed phase separation with heterogeneity domains of about 1 µm. Therefore, it is properly concluded that ternary PCHMA/PαMS/P4M is partially miscible with a small closed‐loop immisciblity range, even though all the constituent binary pairs are fully miscible. Thermodynamic backgrounds leading to decreased miscibility and greater heterogeneity in a ternary polymer system in comparison with the binary counterparts are discussed. © 2003 Society of Chemical Industry