Mobility Influences on the Capacity of Wireless Cellular Networks

Capacity has always been a major concern in wireless networks. This letter studies the impact of mobility on the overall system capacity in wireless cellular networks. In this letter, we present a simple system model which we developed to capture the inherent relationships among system capacity, new call blocking probability, handoff dropping probability, call terminating probability, and bandwidth utilization rate. We investigate the complex relationship between mobility and capacity‐related parameters. Through simulation, we demonstrate that mobility has a significant impact on capacity and is reversely proportional to the bandwidth reserved for handoff traffic.     

Total Dose Radiation Tolerance of Phase Change Memory Cell with GeSbTe Alloy

Phase change memory （PCM） cell array is fabricated by a standard complementary metal-oxide-semiconductor process and the subsequent special fabrication technique. A chalcogenide Ge2Sb2Te5 film in thickness 50hm deposited by rf magnetron sputtering is used as storage medium for the PCM cell. Large snap-back effect is observed in current-voltage characteristics, indicating the phase transition from an amorphous state （higher resistance state） to the crystalline state （lower resistance state）. The resistance of amorphous state is two orders of magnitude larger than that of the crystalline state from the resistance measurement, and the threshold current needed for phase transition of our fabricated PCM cell array is very low （only several μA）. An x-ray total dose radiation test is carried out on the PCM cell array and the results show that this kind of PCM cell has excellent total dose radiation tolerance with total dose up to 2 ×10^6 rad（Si）, which makes it attractive for space-based applications.     

膨胀的热夸克胶子物质的中等质量双轻子的增强

基于一个描述夸克胶子火柱演化的相对论流体力学模型,研究了夸克相、强子相互作用以及非热过程(DrellYan对、粲强子衰变)的中等质量双轻子的产生.发现由于相边对夸克胶子物质演化的影响和RHIC能量核碰撞产生的夸克胶子物质具有高的初始温度,夸克相对双轻子的贡献显著增强,比那些来自强子相互作用的贡献重要,甚至能与来自非热的贡献比较.表明中等质量双轻子的增强是一个在核碰撞中产生了夸克胶子物质的可能信号. 关键词： 夸克-胶子物质 双轻子增强 相对论流体力学模型     

Temperature dependence of interband transition energy in InGaAsN strain-compensated quantum-well and ridge-waveguide lasers fabricated with pulsed anodic oxidation

Ridge-waveguide InGaAsN triple-quantum-well strain-compensated lasers grown by metal organic chemical vapor deposition were fabricated with pulsed anodic oxidation. The laser’s output power reached 145 mW in continuous-wave mode at room temperature for a 4-?m -stripe-width laser. Continuous-wave single longitudinal mode operation was maintained at a high injection current level with a wavelength of 1287.3 nm at room temperature. Single longitudinal mode operation at 1317.2 nm was achieved at twice the threshold current at 100 °C. The band gap of InGaAsN in the quantum wells at different temperatures was calculated and compared to the measured temperature-dependent laser wavelength.     

Engineering issue study of triple harmonic method for in situ flying height analysis

In situ flying height testing technology is becoming more and more important in slider–disk interaction analysis and manufacturing quality control of disk drives and head-related components. Triple harmonic method is a quite promising choice for in situ flying height analysis, compared with other in situ methods reported up to now. This paper reports results of investigations on engineering issues of applying triple harmonic method for in situ flying height analysis. The paper reports results of analysis on the effects of various testing conditions on flying height testing repeatability and accuracy. Results suggest that working at reasonable high channel density and working on the ratio between third and first harmonics will be an advantage in terms of both flying height testing sensitivity and testing repeatability. Comparing with media thickness effect, the gap-length variation among different heads will be important if it is to study flying height difference among different heads and the testing is at high channel density. Also, it is suggested to work at AC erased track, in order to reduce the non-linearity caused by hard transition.     

喷气式Z箍缩等离子体辐射软X射线能谱的研究

研制了一台五通道ROSS-FILTER-PIN软X射线能谱仪，能谱范围为0.28—1.56keV.它由5个连续能段组成，每个能段的起止边由罗斯滤片对(ROSS-FILTERS)的L或K吸收边确定.罗斯滤片对的厚度通过优化计算得到，为了使每个通道的灵敏区外响应(即所测能段外响应)与通道总响应之比最小，在滤片对的第二滤片上镀上了一定厚度的第一滤片材料；为了缩减滤片表面积以增强低能滤片的抗冲击能力及方便滤片加工，能谱仪采用了小探测面积的PIN探测器(1mm²).借助此能谱仪，测量得到了喷气式Z箍缩(Z-pinch)等离子体辐射软X射线能谱的分布，并研究了软X射线产额随箍缩状况的变化趋势. 关键词： Z箍缩等离子体 罗斯滤片 软X射线能谱     

新型金属杂冠醚配合物18-MC-6[Mn6(4-Amashz)6(DMF)6]·12DMF的合成

合成了一种新型金属杂冠醚配合物[Mn6(4-amashz)6(DMF)6]·12DMF,并用X射线衍射法对其结构进行了表征.研究了该化合物修饰金电极催化氧还原的性质,结果表明,该化合物具有平面碟状结构,对在碱性溶液中的氧有显著的催化还原作用.     

Photoluminescence characteristics of ZnTiO3: Bi nanocrystals

The photoluminescence properties of the Bi³⁺ in sol-gel derived ZnTiO₃ nanocrystals have been investigated. An ultra-violet emission at 360 nm and a visible emission band at 506 nm have been observed, originating from two kinds of emission centers. The former is ascribed to the ³P₁-¹S₀ transition of Bi³⁺ and the latter to the recombination of the electrons with the photo-generated holes trapped in the zinc vacancies. In all cases the latter contribution is predominant.