静态电压稳定域边界的非线性近似解析表达

在电力系统控制决策与运行分析中,对系统稳定运行区域的边界面几何形状的认识具有重要的意义。文中对注入功率空间中静态电压稳定域边界面(即潮流可解域边界)的二次特性进行了深入的探讨。通过对潮流方程雅可比矩阵的行列式在临界点附近进行泰勒级数展开并保留二次项,得到了计及非线性项的边界近似解析表达式。在计算过程中应用了潮流方程特征值和特征向量灵敏度系数的计算。该方法的优点是算法本身不涉及任何非线性方程的迭代求解,且所提出的非线性解析表达式能在大范围内较好地逼近真实稳定域边界。通过IEEE系统的算例对所提出的方法的精确性进行了验证。     

Enhancement of Ferroelectric Properties of Pb(Zr,Ti)O3 Films Grown by Metal-Organic Chemical Vapor Deposition on Noble-Alloy Bottom Electrodes

Pb(Zr,Ti)O₃ (PZT) films grown on Ir electrodes by a metal-organic chemical vapor deposition (MOCVD) have suffered from high leakage and rough surface. We sputtered Pt and Ir simultaneously onto Ti/SiO₂/Si substrates and formed Ir-Pt alloy bottom electrodes with various compositions. With an optimal composition of Ir and Pt, PZT films grown by MOCVD on this substrate showed smoother surface and suppressed leakage via the bottom interface. At the specific composition of Ir and Pt, two different phases seemed to be acquired. They constituted the electrodes and affected the PZT grain nucleation independently so that the grains with different origins grew and restrained the vicinal grains, and finally soothed the faceted-grain-formation. No fatigue was observed even in PZT on Ir-Pt alloy with much Pt content.     

FABRICATION AND ELECTRICAL PROPERTIES OF PZT-PVDF 0–3 TYPE COMPOSITE FILM

ABSTRACT

A film speaker was fabricated with 0–3 type piezoelectric composite. The 0–3 type composite was developed to incorporate the advantages of both ceramic and polymer. The pastes of PZT-PVDF composite were made with various mixing ratio. The paste was printed by conventional screen-printing method on ITO (Indium Tin Oxide) bottom electrode which was deposited on PET (polyethylene terephthalate) polymer film. The prepared composite film was about 80 μm in thickness. After printing the top-electrode of silver-paste, 4 kV/mm of DC field was applied at 120°C for an hour to align the electric dipole in the 0–3 composite film. The piezoelectric charge constant of d₃₃ was increased with increasing the PZT weight percent. The maximum value was 24 pC/N at 70 wt% of PZT. But the piezoelectric voltage constant of g₃₃ had the maximum value about 32 mV · m/N at 65 wt% of PZT. The SPL (Sound Pressure Level) of the speaker fabricated with the 65:35 composite film was tested at various driving voltages of 1 ～ 100V_rms. The SPL was saturated at the driving voltage of 70V_rms and the value was about 68 dB at 1 kHz.     

Investigation on Resistive Memory Switching Mechanism of NiO

ABSTRACT

Experimental investigations on the resistive memory switching in sub-micron sized NiO memory cell are presented to elucidate the resistive memory switching mechanism. The voltage or current-biased I-V measurements show that the resistive switching transitions can be regarded as the combination of a voltage-controlled negative differential resistance phenomenon and a current-controlled negative differential resistance phenomenon. Along with experimental observations of multiple resistance states, these indicate that the memory switching in NiO would come from the percolative formation and rupture of filamentary conducting paths. Pulse experiments further suggest that the memory switching would come from local domains inside filaments.     

Efficient and secure source authentication scheme for multicast user authentication

Multicast technology application has been widely utilized in broadband internet. Source authentication is one of the most needs for many multicast applications transferring real-time information such as stream video and online news. Because multicast current services provided to the group members are changed dynamically, data transferring by a group member is not used by the recipient. In order to verify the identity of the sender who sent the packet and to make sure that the data have not been tampered, an optimized source authentication scheme has been proposed to transfer the authentication information not to the next-door packet. The proposed method for multiple packets authenticates the source with a limited number of electronic signatures. The proposed method can reduce overhead compared to the method by adding a digital signature for every packet. In addition, by sending the generated electronic signature to the first packet and the last packet, it prevents the loss of consecutive packets, as well as a source authentication can be provided in real-time services.     

Smooth cutting pattern generation technique for membrane structures using geodesic line on subplane and spline interpolation

Practical techniques for smooth geodesic patterning of membrane structures were investigated, For the geodesic search, adjustment of the subplane of the extracted elements series was proposed, and various spline approximation methods were used to flatten the strip for the generation of a smooth pattern. This search approach is very simple, and the geodesic line could be easily attained by the proposed method without the need for a difficult computation method. Smooth cutting patterning can also be generated by spline approximation without the noise in discrete nodal information. Additionally, the geodesic cutting pattern saved about 21% of the required area for the catenary model due to the reduction of the curvature of the planar pattern seam line.     

Joint member angle limits of composite beams and CFT square columns

This work aims to understand the relationship between the member angle limit and the energy ratio for 24 test samples of composite beams and CFT square steel tube columns. This work also compares the formula applicability for member angle limit with the previous test result to provide the basic data for the design of composite beam-CFT column. The evaluation of the member angle limit was performed with concrete compressive strength (fC =22.16 MPa, 30.49 MPa), breadth-to-thickness ratio (B/t=25.0, 33.3, 43.5), and axial capacity ratio (N/N0=0, 0.3, 0.4, 0.5) as the main variables of the test samples. For the relationship between the member angle limit (Ru) and the energy ratio (ES/EC ), the test result shows that the energy ratio becomes lower as the axial capacity ratio and the breadth-to-thickness ratio increase. The energy ratio is lower for the Type B test sample compared with that of Types A and C. For the formula suggested by SATO, the test samples are distributed evenly for comparison between test values and the member angle limit; however, other formulas indicate a deviation. Specifically, for the comparison between R u,cal and R u (Test), Maeda’s formula shows severe deviation.     

A new type of ordering in Ba(Zn1/3 Ta2/3)O3 ceramics

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

Grain growth of copper films prepared by chemical vapour deposition

Copper films having thickness 600 nm were prepared on TiN using chemical vapour deposition (CVD). The deposited films were annealed at various temperatures (350–550°C) in Ar and H₂(10%)-Ar ambients. The changes in the grain size of the films upon annealing were investigated. Annealing in an H₂(10%)-Ar ambient produced normal grain growth; annealing in an Ar ambient caused grain growth to stop at 550°C. The grain size followed a monomodal distribution and the mean size increased in proportion to the square root of the annealing time, indicating the curvature of the grain is the main driving force for grain growth. Upon annealing at 450°C for 30 min in an H₂(10%)-Ar ambient, the average grain size of the film increased from 122 nm to 219 nm, and the resistivity decreased from 2.35 μΩ cm to 2.12 μΩ cm at a film thickness of 600 nm. This revised version was published online in July 2006 with corrections to the Cover Date.