陷阱型双通带声表面波滤波器的设计

研究比较了几种陷阱型双通带声表面波滤波器的设计方法。实验表明，采用组合式均匀叉指换能器及变形多条耦合器元件可有效提高对陷阱频率的抑制。     

Two Novel Sesquiterpenoids from the Roots of Ferula ferulaeoides (Steud.) Korov.

Two new sesquiterpenoids, ferulactones A and B ( 1 and 2 , resp.), have been isolated from the roots of Ferula ferulaeoides (Steud.) Korov . Their structures and relative configurations were established by analysis of spectroscopic data. Their absolute configuration was assigned by application of the CD technique.     

Theoretical mechanisms of the superoxide radical anion catalyzed by the copper‐zinc superoxide dismutase

The disproportionation of superoxide radical anions catalyzed by copper‐zinc superoxide dismutase was investigated in detail using density functional theory. The structures of each stationary point and the transition states were located so that the reaction pathways were determined. The results indicate that the reactions proceed by two steps both for the oxidized process of superoxide radical anion and the reduced one. The rate for the determining step of the reaction (2) is in very good agreement with the experimental value. The solvation effect on the reaction was also discussed. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Cellulosic fiber: mechanical fibrillation-morphology-rheology relationships

Cellulose - This study aims to investigate the relationship between mechanical fibrillation, morphological properties, and rheological behavior of cellulosic fiber. Three types of cellulosic fibers...     

Rapid design space exploration by hybrid fuzzy search approach for optimal architecture determination of multi objective computing systems

Design Space Exploration (DSE) with multi-parametric objective in High Level Synthesis (HLS) involves assessing the various design points in the architecture design space to find the optimum solution for the design according to the system requirements specified. Due to the time to market pressure, the cost of solving the problem of architecture selection by exhaustive analysis is strictly forbidden. The tradeoffs linked to the selection of the appropriate design point during architecture evaluation needs careful assessment for efficient design space exploration. Further DSE requires satisfying multiple conflicting multi objective conditions such as increase in accuracy of evaluation during DSE with simultaneous speedup in the exploration process. This paper presents a novel hybrid design space exploration approach which is a combination of the Priority Factor (PF) method and Fuzzy search technique that is rapid and accurate in architecture evaluation and selection. The proposed approach for DSE when applied on a number of benchmarks yielded superior results compared to the current existing DSE approach for architecture selection. The comparison results of the proposed hybrid approach with the current existing approach for different benchmarks are shown and the speedups obtained are also presented.     

茶叶中锰、铁、锌、铬等10种微量元素的快速测定

茶叶样品经粉碎干燥后,以硝酸-高氯酸混合液进行消解处理,火焰原子吸收分光光度法测定了K、Ca、Na、Mg、Fe、Mn、Cu、Zn、Ni、Cr的含量。结果表明,回收率在89.30%～103.20%之间,相对标准偏差小于10%。方法简单、快速、经济,结果可靠。     

Sol–gel nanocoating on commercial TiO<Subscript>2</Subscript> nanopowder using ultrasound

The surface of commercial titania particles was coated by a layer of silica by a two-step process which involved a power ultrasound initiated sol–gel reaction. In the first step of this solution process, aminosilane, i.e. organosilane with amino functional group, was used to modify the surface of pristine nanoparticles. Subsequent silica nanocoating was initiated and sustained under power ultrasound agitation in a mixture of surface modified particles and epoxysilane. As a result, a homogenous coverage of silica on the nanoparticles’ surface, with thickness controllable from one to several nanometers, was obtained. Fourier transform infrared spectroscopy (FTIR), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and particle surface zeta potential measurements were employed to follow steps in the process and to confirm the reaction mechanism.     

Thermal Cycling Reliability of Sn-Ag-Cu Solder Interconnections. Part 1: Effects of Test Parameters

The work presented in part 1 of this study focuses on identifying the effects of thermal cycling test parameters on the lifetime of ball grid array (BGA) component boards. Detailed understanding about the effects of the thermal cycling parameters is essential because it provides means to develop more efficient and meaningful methods of reliability assessment for electronic products. The study was carried out with a single package type (BGA with 144 solder balls), printed wiring board (eight-layer build-up FR4 structure), and solder interconnection composition (Sn-3.1Ag-0.5Cu) to ensure that individual test results would be comparable with each other. The effects of (i) temperature difference (ΔT), (ii) lower dwell temperature and lower dwell time, (iii) mean temperature, (iv) dwell time, and (v) ramp rate were evaluated. Based on the characteristic lifetimes, the thermal cycling profiles were categorized into three lifetime groups: (i) highly accelerated conditions, (ii) moderately accelerated conditions, and (iii) mildly/nonaccelerated conditions. Thus, one might be tempted to use the highly accelerated conditions to produce lifetime statistics as quickly as possible. However, to do this one needs to know that the failure mechanisms do not change from one lifetime group to another and that the failure mechanisms correlate with real-use failures. Therefore, in part 2 the observed differences in component board lifetimes will be explained by studying the failure mechanisms that take place in the three lifetime groups.     

VPO催化剂的制备及其表征

采用ＢＥＴ、ＸＲＤ等测试手段，考察了由四种不同方法和条件下制备的ＶＰＯ催化剂的比表面积和晶体结构。实验结果表明：还原剂、溶剂、Ｐ／Ｖ、干燥条件及焙烧温度都对ＶＰＯ催化剂的物理性质有影响。水相法制备，获较复杂的晶相，且随着焙烧温度的提高样品的比表面积减小，晶相强度增加。有机相法制备，可获得较单一、活性好的晶相，且焙烧温度提高对样品的比表面积影响不大，但超临界条件下干燥，可使催化剂比表面积成倍地增大