一种闪存敏感的多级缓存管理方法

基于闪存的固态硬盘(solid state driver,简称SSD)已经广泛应用于各种移动设备、PC机和服务器.与磁盘相比,尽管SSD具有数据存取速度高、抗震、低功耗等优良特性,但SSD自身也存在读写不对称、价格昂贵等不利因素,这使得SSD 短期内不会完全取代磁盘.将SSD和磁盘组合构建混合系统,可以发挥不同的硬件特性,提升系统性能.基于 MLC 型 SSD 和 SLC 型 SSD 之间的特性差异,提出了一种闪存敏感的多级缓存管理策略——FAMC.FAMC将SSD用在内存和磁盘之间作扩展缓存,针对数据库系统、文件管理中数据访问的特点,有选择地将内存牺牲页缓存到不同类型的SSD.FAMC同时考虑写请求模式和负载类型对系统性能的影响,设计实现对SSD友好的数据管理策略.此外,FAMC基于不同的数据置换代价提出了适用于SSD的缓冲区管理算法.基于多级缓存存储系统对FAMC的性能进行了评测,实验结果表明,FAMC可以大幅度降低系统响应时间,减少磁盘I/O.     

Polyhedral Objects Metamorphosis Using Convex Decomposition and Morphology

A new technique is presented for computing continuous shape transformations between polyhedral objects. The polyhedron shape transformations can be divided into polyhedron metamorphosis and bi-directional local rigid body rotation transformation. By decomposing two objects into sets of individual convex sub-objects respectively, and establishing the matching between two subsets, the approach can solve the metamorphosis problem of two non-homotopic objects (including concave objects and holey objects). Compared with other methods, this metamorphosis algorithm can be executed automatically for arbitrary polyhedrons and no need user interaction. The user has the ability to choose an automatic matching or to select interactively pairs of corresponding matching convex subsets to obtain special effects. Experiments show that this method can generate natural, high-fidelity, eye-pleasing metamorphosis results with simple computation.     

Enhanced thermoelectric performance via randomly arranged nanopores: Excellent transport properties of YbZn2Sb2 nanoporous materials

Fabricating nanoporous bulk thermoelectric (TE) materials with periodically arranged nanopores is highly challenging and expensive, although TE materials exhibit high power factors (α²σ) and low thermal conductivities (κ). Enhanced TE performance via randomly arranged nanopores is demonstrated with a YbZn₂Sb₂ nanoporous material (nPM) fabricated by a combination of melt quenching and two stage spark plasma sintering in less than 10 h. Measurement of the electrical conductivity, Hall mobility, Seebeck coefficient, and thermal conductivity show that simultaneously enhancing α²σ and reducing κ can realize in the YbZn₂Sb₂ nPM with randomly arranged nanopores about 50-200 nm in diameter. Compared with YbZn₂Sb₂ dense bulk materials (dBM) fabricated by a conventional method taking more than 180 h, α²σ at 300 K increases by 122%, κ at 300 K decreases by 29%, and the maximum ZT value at 775 K reaches 0.67, increasing by 46% for the nPM725 sample. This work shows that a periodic arrangement of nanopores is not essential for the fabrication of attractive TE materials, which offers a wider approach to nanostructure engineering to improve TE performance.     

六自由度奈米测量机之量测系统组装及校正

介绍一个六自由度奈米级精度测量机台(行程为25mm×25mm)之量测系统的组装及系统的校正,此六自由度奈米测量机分为两部份,第一部分为利用五根压电致动器所组成的四自由度(Z、θx、θy、θz)补偿平台,用以补偿组装及加工误差.第二部份为利用V型导轨架构成之XY双轴滑轨平台,配合音圈马达之推动,使平台能达到XY轴向之定位...     

A Novel Dynamic Adjusting Algorithm for Load Balancing and Handover Co-Optimization in LTE SON

With the development of mobile internet and multi-media service, advanced techniques need to be applied in wireless network to improve user experience. Long term evolution (LTE) systems, which can offer up to 100Mbps downlink date rates, have been deployed in USA and Korea. However, because plenty of complex physical layer algorithms are utilized, network planning and optimization become heavy burdens for LTE network operators. Self-organizing network (SON) is a promising method to overcome this problem by automatically selecting and adjusting key parameters in LTE systems. In this paper, we present a dynamic adjusting algorithm to improve both handover and load balancing performance by introducing a weighted co-satisfaction factor (CSF). Analysis and system level simulation are conducted to exhibit the performance improvement of the proposed scheme. Results show that the proposed method outperforms the conventional solutions in terms of the network handover success ratio and load balancing gains significantly.     

一种变权灰色组合预测模型在中长期电力负荷预测中的应用

提出了一种基于灰色理论的中长期负荷变权组合预测模型,通过分析负荷曲线走向,对不同变化趋势的阶段组合后建立不同的灰色模型分别进行预测,通过基于累加残差的变权组合预测得到最终结果,简单有效地将变权组合预测应用到电力负荷预测中.实例计算证明了该模型在中长期电力负荷预测中的有效性,该模型兼具了灰色模型的简单性和变权组合预测的精确性.     

聚合物共混物对水泥石-石英界面结构影响的机理

就聚合物共混物对水泥石－石英界面结构的影响机理进行了研究,结果表明：在聚合物共混物改性水泥砂浆中,石英表面的水化离解反应因聚合物分子链活性基因的电性作用而失去平衡,导致其表面出现大量带负电荷的「ＨＳｉＯ３」＾－和「ＳｉＯ３」＾２－离子;「ＨＳｉＯ３」＾－和「ＳｉＯ３」＾２－离子与水泥水化阳离子相互作用,在石英表面产生如水化硅酸钙等凝胶状粘结物,从而形成水泥石－石英粘附性界面。     

多媒体教学与传统教学在高职教学中的利弊分析

随着计算机技术的迅速发展,高职教育的发展也受到影响．多媒体教学手段的广泛应用,使传统教学方法受到很大冲击,本文阐述了多媒体教学的特点和传统教学的特点及缺陷,寻找一种结合两种教学方法的新型的合适高职的教学方法。     

FTIR Spectra, Lattice Shrinkage, and Magnetic Properties of CoTi-Substituted M-Type Barium Hexaferrite Nanoparticles

Single-phase BaCoTiFe₁₀O₁₉ (BaCoTi-M) nanoparticles were prepared by a modified sol–gel process, using metallic chlorides as starting materials. The physical chemistry process of BaCoTi-M formation, the interdependences between composition, technological conditions, microstructure, and magnetic properties were studied by X-ray diffraction (XRD), Fourier transform-infrared (FTIR), scanning electron microscope (SEM), transmission electron microscope (TEM), and vibrating sample magnetometer (VSM). XRD and FTIR results show that BaCoTi-M nanoparticles formed directly from γ-Fe₂O₃, spinel ferrite, and barium salts without the formation of α-Fe₂O₃ and BaFe₂O₄. The lattice shrinkage of BaCoTi-M nanoparticles that occurred on increasing the calcining temperature from 973 to 1173 K under holding for 2 h or on increasing the holding time in the range 0–2 h at 1173 K was discovered by analyzing the dependences of lattice parameters on the heat-treatment conditions. The shrinkage led to a relatively higher concentration of magnetic Fe³⁺ cations in the unit cell, and resulted in an increase of specific saturation magnetization under the corresponding conditions. Microstructural characterization shows that the evolutions of coercivity, remnant magnetization, and squareness ratio depended on the crystal growth and the reduction of structural defect as well as a decrease of grain boundary.     

Seismic design requirements for reinforced concrete piers considering aftershock-induced seismic hazard

The main purpose of this study is to develop an estimation procedure of seismic design level setting for reinforced concrete (RC) piers considering aftershock-induced seismic hazards. This work develops an assessment method of the seismic hazards induced by aftershocks and takes an example of the Chi–Chi Earthquake in Taiwan. The number of aftershocks is assumed to follow the modified Gutenberg–Richter law with lower and upper bounds when analysing the cumulative density function of the magnitude of the aftershock within a specified post-mainshock period for the earthquake. Additionally, this work considers the spatial uncertainty in the hypocentres of aftershocks to assess the aftershock-induced seismic hazards. Fragility curves and residual factors of damaged RC piers are used in the transition probability matrix of Markov Chain model for considering the cumulative damage induced by aftershocks by incorporating uncertainty into aftershock events, as well as into structural capacity and residual factors corresponding to a specified damage state, the exceedance probabilities for various damage states can be estimated using Markov Chain model and Monte Carlo Simulation. Finally, in the case study, the proposed procedure is used to determine the important factor in the preliminary seismic design of typical RC piers for the Chi–Chi Earthquake in Taiwan.