一种新的分布式QoS控制动态资源调配算法

该文提出了一种新的分布式环境下用于QoS控制的基于模糊逻辑的动态资源调配(Fuzzy logic based Dynamic Resource Allocation,FDRA)算法。分布式环境采用集中式带宽代理(Bandwidth Brokers, BB))与分布式BB相结合的控制模式。分布式BB基于滑动窗口和滑动指针机制,在分配资源不足时向集中式BB请求追加资源,在占用资源高于需求一定阈值时滞后释放部分追加资源。追加资源块和释放资源块的大小分别由集中式BB和分布式BB根据当前网络负荷状态,采用模糊逻辑确定。模糊逻辑算法引入新的基于数据源特性的隶属度函数生成方法,提高决策的有效性。仿真结果证明,该文提出的算法性能优于已有文献的算法。     

Holstein 分子晶体模型能带结构的温度依赖性

研究了温度对Holstein分子晶体模型能带结构的影响,结果表明固体的能带宽度和禁带宽度都与电子和热声子相互作用以及热膨胀密切相关.对一维Li原子品格链,在所选定的参数下,1s和2s的能带宽度随着温度的增加而变窄,两带之间的禁带宽度变宽,这些结果与实验结果在定性上是一致的.显然,研究能带结构的温度依赖性对于理解固体的光学和输运性质都是十分重要的.     

Data retention characteristics of MANOS-type flash memory device with different metal gates at various levels of charge injection

We investigated the impact of charge injection and metal gates (Al and Pt) on the data retention characteristics of metal–alumina–nitride–oxide–silicon (MANOS) devices for NAND flash memory application. Through the theoretical and experimental results, the highly injected charge (ΔV_TH) could cause the band bending of Al₂O₃, which reduced the tunneling distance across Al₂O₃. Thus, the dominant charge loss path is not only toward SiO₂ but also toward Al₂O₃ direction. Compared to low-metal work function (Ф_M), ONA stack with high-Ф_M showed better data retention characteristics, even if ΔV_TH is high. This could be explained by Fermi level alignment for different Ф_M, which results in the reduction of electric field across the Al₂O₃ compensated by the ΔФ_M (Ф_Pt ? Ф_Al).     

Oxygen Surface Exchange at Grain Boundaries of Oxide Ion Conductors

The role of grain boundaries on oxygen surface exchange in an oxide ion conductor is reported. Atomic‐scale characterization of the microstructure and chemical composition near the grain boundaries of gadolinia‐doped ceria (GDC) thin films show the segregation of dopants and oxygen vacancies along the grain boundaries using the energy dispersive spectroscopy in scanning transmission electron microscopy (STEM‐EDS). Kelvin probe microscopy is employed to verify the charge distribution near grain boundaries and shows that the grain boundary is positively charged, indicating a high concentration of oxygen vacancies. AC impedance spectroscopy on polycrystalline GDC membranes with thin interfacial layers with different grain boundary densities at the cathodes demonstrated that the cells with higher grain boundary density result in lower electrode impedance and higher exchange current density. These experimental evidences clearly show that grain boundaries on the surface provide preferential reaction sites for facilitated oxygen incorporation into the GDC electrolyte.     

微型光纤光谱仪的波长定标分析

为了提高光纤光谱仪的测量精度,采用标准汞氩灯谱线和最小二乘法的3阶线性拟合,取得了完整的波长定标方案。结果表明,算术平均误差小于0.167nm,标准差小于0.217nm,波长与像素的拟合相关程度较高;定标后波长不确定度优于0.11nm,误差小于0.15nm,波长重复性可达0.01nm。这一结果对提高光谱仪实际应用中的测量精度是非常有益的。     

Self‐Interference Cancellation for Shared Band Transmission in Nonlinear Satellite Communication Channels

For efficient spectral utilization of satellite channels, a shared band transmission technique is introduced in this paper. A satellite transmits multiple received signals from a gateway and terminal in the common frequency band by superimposing the signals. To improve the power efficiency as well as the spectral efficiency, a travelling wave tube amplifier in the satellite should operate near the saturation level. This causes a nonlinear distortion of the superimposed transmit signal. Without mitigating this nonlinear effect, the self‐interference cannot be properly cancelled and the desired signal cannot be demodulated. Therefore, an adaptive compensation scheme for nonlinearity is herein proposed with the proper operation scenario. It is shown through simulations that the proposed shared band transmission approach with nonlinear compensation and self‐interference cancellation can achieve an acceptable system performance in nonlinear satellite channels.     

Effects of isothermal aging and temperature–humidity treatment of substrate on joint reliability of Sn–3.0Ag–0.5Cu/OSP-finished Cu CSP solder joint

This study examined the effects of isothermal aging and temperature–humidity (TH) treatment of substrate on the joint reliability of a Sn–3.0Ag–0.5Cu (wt.%)/organic solderability preservative (OSP)-finished Cu solder joint. Two types of OSP-finished chip-scale-package (CSP) substrates were used, those subjected and not subjected to the TH test. This study revealed an association between the interfacial reaction behaviors, void formation and mechanical reliability of the solder joint. Many voids were formed at the interface of the OSP-finished Cu joint subjected to the TH test. These voids were caused by the oxidation of the OSP-finished Cu substrate during the TH test. In the shear tests, the shear force of the joint with the substrate not subjected to the TH test was slightly higher than that with the TH test. The mechanical reliability of the solder joint was degraded by voids at the interface.     

计算机技术在桥式自动采样系统中的研究与应用

本论文主要介绍了利用计算机和PLC控制系统,实现对矿粉等各种粉末原材料样品的自动采集实现的方法,并着重介绍了自动采样系统地组成以及控制功能,该系统组成主要有Siemens 300系列PLC控制系统,MicroMaster440系列变频器,绝对式编码器,三相异步电机及其他各种辅助设备。该系统的实现解决了原料厂人工采集样品的现状,在更好的完成生产的需要的同时,实现故障率低、准确、效率高、节省劳动力等诸多优点,使职工的工作环境大大提高,其重要性随着生产应用将更加突出。     

Design of an Ultra‐Wideband Antenna Using a Ring Resonator with a Notch Function

This paper describes an ultra‐wideband (UWB) antenna that uses a ring resonator concept. The proposed antenna can operate in the entire UWB, and the IEEE 802.11a frequency band can be rejected by inserting a notch stub into the ring resonator. The experiment results indicate that the measured impedance bandwidth of the proposed antenna is 17.5 GHz (2.5 GHz to at least 20 GHz). The proposed UWB antenna has omnidirectional radiation patterns with a gain variation of 3 dBi (1 dBi to 4 dBi).     

Advantages of CDMA and spread spectrum techniques over FDMA andTDMA in cellular mobile radio applications

A unified theoretical method for the calculation of the radio capacity of multiple-access schemes such as FDMA (frequency-division multiple access), TDMA (time-division multiple access), CDMA (code-division multiple access) and SSMA (spread-spectrum multiple access) in noncellular and cellular mobile radio systems is presented for AWGN (additive white Gaussian noise) channels. The theoretical equivalence of all the considered multiple-access schemes is found. In a fading multipath environment, which is typical for mobile radio applications, there are significant differences between these multiple-access schemes. These differences are discussed in an illustrative manner revealing several advantages of CDMA and SSMA over FDMA and TDMA. Novel transmission and reception schemes called coherent multiple transmission and coherent multiple reception are briefly presented