超声波(微波)条件下硅藻土对亚甲基蓝吸附性能的研究

用超声波(微波)辅助分光光度法研究硅藻土对亚甲基蓝吸附性能,在亚甲基蓝的剩余浓度为8.0×10-6g/ml范围内呈良好的线性关系。振荡时间、溶液pH、共存离子对吸附都有影响。实验表明:在超声波中超声8min,微波中低档辐照60s,pH=9.0的缓冲溶液和15mlNa4P2O7的条件下,吸附比较完全。     

Novel optimal real‐time admission control and buffer management for the Video‐On‐Demand (VOD) service

In order to meet the Quality of Service (QoS) requirements of the VOD service, and, on the other hand, to maximize the system throughput (revenue), it is essential that the video call request admission control algorithm be carefully designed. In this paper, in addition to the Single Segment (SS) admission control first described in [7], we propose two new types of admission control schemes called Segmental Re‐tuned (SR) admission control and Multiple Segment (MS) admission control for variable‐bit‐rate video streams under various video server architectures. The basic approach to the algorithm development is first to formulate each problem as a mathematical problem and then to identify special structures and properties for such formulations so that optimal real‐time algorithms can be developed. In computational experiments, it is shown that the proposed algorithms for the considered video server architectures, compared with the traditional admission control scheme based upon the peak frame size, typically achieve over 175–200% improvement in the system throughput. In addition, the new proposed MS scheme performs 5–25% better than SS and SR schemes. This revised version was published online in June 2006 with corrections to the Cover Date.     

基于Matlab虚拟现实3D动画显示模块的卫星地面仿真系统

由于传统的地面仿真系统往往是基于VC++语言开发的,开发过程非常复杂,并且进行卫星模拟在轨状态显示时仅能显示数据,或者通过难度很大的OpenGL、D3D等3D编程技术才能进行3D动画显示,造成开发周期长,开发难度大,并且可修改性与可移植性均很差。文章提出了一种新的基于Matlab虚拟现实3D动画显示模块卫星地面仿真系统,采用Matlab已有的模块搭建仿真系统的数学模型及显示系统,可以大大减小系统开发的难度,并且具有3D显示功能。     

汽轮机叶片围带脱落的原因分析及修复

分析了乌拉山发电厂2号汽轮机第16、17级叶片的围带多次大修解体发现脱落现象的原因,提出了2种修复方案。通过比较分析,选择了在叶片上直接焊铆钉头的方法进行了修复,取得了较好的效果。     

实现水工大体积混凝土高性能化问题的探讨

由于水工大体积混凝土自身的特殊性，传统的设计模式及其所处的特殊环境，已经显示出其耐久性严重不足，主要表现为渗漏，溶蚀、侵蚀、冻融破坏和钢筋锈蚀，而高性能混凝土自身的特点及其在许多水电工程中的成功应用，已经证明实现水工大体积混凝土高性能化是解决其耐久性问题的基本途径，但是，目前尚需要解决高性能混凝土的造价问题和混凝土的新旧设计方法，设计观念之间的矛盾问题，这些问题可以通过更新设计观念、优选材料、优化     

长钢球团降低膨润土消耗生产实践

结合长钢烧结厂实际生产情况，总结介绍了长钢烧结厂在降低竖炉球团膨润土消耗方面所取得的一些生产经验。     

Output feedback control with optimal gains for a one‐link flexible robot arm

Abstract

An output feedback control law is proposed to control a flexible robot arm with co‐located actuator and sensors. The design of the control law is based on a truncated model of the flexible robot arm. The feasible directions method, an optimization technique, is used to synthesize the feedback gains of proposed control law. The proposed control law is simple and easy to implement, it is robust to modal truncation and to parameter variations. Numerical simulation shows that the performance of the controlled system is satisfactory.     

Nonfullerene organic photovoltaic cells exhibiting 13.76% efficiency by employing upside‐down solvent vapor annealing

Organic photovoltaic cells (OPVs) are fabricated with a polymer donor PM7 and a nonfullerene acceptor IT‐4Cl; the morphology of active layers is optimized by employing upside‐down solvent vapor annealing (UD‐SVA) method with different annealing solvents. The OPVs with CS₂ as annealing solvent exhibit optimized power conversion efficiency (PCE) of 13.76%, with simultaneously increased short‐circuit current density (J_SC) of 20.53 mA cm^?2 and fill factor (FF) of 77.05%. More than 15% PCE improvement can be achieved by employing CS₂ UD‐SVA treatment, which should be attributed to slightly enhanced photon harvesting, efficient exciton separation, charge transport, and collection, resulting from the well‐developed morphology of active layer. Moreover, the PM7:IT‐4Cl–based OPVs with CS₂ as annealing solvent still can maintain PCE more than 13% in a wide treatment time range from 20 to 90 seconds. This work demonstrated that UD‐SVA has great potential in improving the performance of nonfullerene OPVs.     

Effects of Non‐Stoichiometry on the Microstructure,Oxygen Vacancies,and Piezoelectric Properties of CuTa2O6‐Doped NKN Ceramics

The effects of non‐stoichiometry on the microstructure, oxygen vacancies, and piezoelectric properties of (Na_0.5K_0.5)_xNbO₃ (NKxN, where x = 0.98, 1.00, 1.01, and 1.02) ceramics doped with sintering aid CuTa₂O₆ (CT) doping were investigated. X‐ray diffraction (XRD) patterns indicated that a secondary phase formed in CT‐doped NKxN (NKxNCT) ceramics with x < 1.00 and that a pure phase was obtained with x ≥ 1.00. The grain size of NKxNCT ceramics increased with increasing x value due to the formation of a liquid phase. The internal bias field, activation energy, and Raman analysis for NKxNCT ceramics showed that the number of induced oxygen vacancies increased with decreasing x value. The high mechanical quality factor (Q_m) value obtained for NKxNCT ceramics did not correspond to a higher concentration of oxygen vacancies, illustrating that the suitable compensation (excess Na and K) is more important than the concentration of oxygen vacancies to obtain the ceramics with high Q_m values. The NKxNCT ceramics with x = 1.01 exhibited excellent piezoelectric properties, with k_p and Q_m values of 39.9% and 2,070, respectively.     

Oxidation behavior of nickel coating on ferritic stainless steel interconnect for SOFC application

The oxidation behavior of nickel coated ferritic stainless steel SS441 has been investigated. A nickel coating layer is deposited on the steel which is employed in a solid oxide fuel cell stack as interconnect. The nickel film is about 8 μm thick and is topped by an additional 4 μm thick La_0.67Sr_0.33MnO₃ (LSM) film on the interconnect cathode-contacting surface for the prevention of chromium evaporation from the steel substrate. A 10,000-h 800 °C isothermal ageing on 10 × 10 mm² steel coupons shows a continuous growth of oxide scales up to ∼200 μm in thickness on the surface, consisting of a 100 μm thick iron oxide layer followed by a complex Fe–Ni–Cr spinel structure. A single-cell stack is tested at 800 °C for up to 1226 h and an average degradation rate of 7.5% kh⁻¹ is observed. Oxidation characteristics of the coating system are analyzed after testing. A Fe–Ni spinel phase is found covering most of the surface area. This is attributed to the intensive interdiffusion of iron and nickel during the stack operation and the high intersolubility of the two elements. In both the tests of the steel coupons and the stack, LSM film structures are damaged by the thermally grown Fe–Ni oxides, and the expected Cr-preventing function is limited. The Fe–Ni spinel layer initially forms an effective obstacle against Cr out-migration. However, the increasing content of iron in the spinel phase induces oxide scale spallation afterwards. Though the fast grown Fe–Ni oxide scale can serve as an effective barrier against chromium out-migration, the iron-enriched scale structure is susceptible to corrosion attacks after an extended stack operation period.