Cyclone V FPGA在高带宽存储接口中的应用

文中详细地分析了Altera公司Cyclone V FPGA器件的硬核存储控制器底层架构和外部接口,并在此基础上对Controller和PHY进行了功能仿真。仿真结果表明硬核存储控制器和PHY配合工作时的功能与设计预期相符,性能优良,适合于在当前FPGA的外部存储带宽需求日益增长的场合下应用。     

Thin reduced graphene oxide interlayer with a conjugated block copolymer for high performance non-volatile ferroelectric polymer memory

Polymer ferroelectric-gate field effect transistors (Fe-FETs) employing ferroelectric polymer thin films as gate insulators are highly attractive as a next-generation non-volatile memory. For minimizing gate leakage current of a device which arises from electrically defective ferroelectric polymer layer in particular at low operation voltage, the materials design of interlayers between the ferroelectric insulator and gate electrode is essential. Here, we introduce a new solution-processed interlayer of conductive reduced graphene oxides (rGOs) modified with a conjugated block copolymer, poly(styrene-block-paraphenylene) (PS-b-PPP). A FeFET with a solution-processed p-type oligomeric semiconducting channel and ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) insulator exhibited characteristic source–drain current hysteresis arising from ferroelectric polarization switching of a PVDF-TrFE insulator. Our PS-b-PPP modified rGOs (PMrGOs) with conductive moieties embedded in insulating polymer matrix not only significantly reduced the gate leakage current but also efficiently lowered operation voltage of the device. In consequence, the device showed large memory gate voltage window and high ON/OFF source–drain current ratio with excellent data retention and read/write cycle endurance. Furthermore, our PMrGOs interlayers were successfully employed to FeFETs fabricated on mechanically flexible substrates with promising non-volatile memory performance under repetitive bending deformation.     

Low operational voltage and high performance organic field effect memory transistor with solution processed graphene oxide charge storage media

Low voltage organic field effect memory transistors are demonstrated by adapting a hybrid gate dielectric and a solution processed graphene oxide charge trap layer. The hybrid gate dielectric is composed of aluminum oxide (AlO_x) and [8-(11-phenoxy-undecyloxy)-octyl]phosphonic acid (PhO-19-PA) plays an important role of both preventing leakage current from gate electrode and providing an appropriate surface energy to allow for uniform spin-casting of graphene oxide (GO). The hybrid gate dielectric has a breakdown voltage greater than 6 V and capacitance of 0.47 μF/cm². Graphene oxide charge trap layer is spin-cast on top of the hybrid dielectric and has a resulting thickness of approximately 9 nm. The final device structure is Au/Pentacene/PMMA/GO/PhO-19-PA/AlO_x/Al. The memory transistors clearly showed a large hysteresis with a memory window of around 2 V under an applied gate bias from 4 V to −5 V. The stored charge within the graphene oxide charge trap layer was measured to be 2.9 × 10¹² cm⁻². The low voltage memory transistor operated well under constant applied gate voltage and time with varying programming times (pulse duration) and voltage pulses (pulse amplitude). In addition, the drain current (I_ds) after programming and erasing remained in their pristine state after 10⁴ s and are expected to be retained for more than one year.     

Versatile threshold voltage control of OTFTs via discontinuous pn-heterojunction formation

We demonstrate the versatility of the threshold voltage control for organic thin-film transistors (OTFTs) based on formation of discontinuous pn-heterojunction on the active channel layer. By depositing n-type dioctyl perylene tetracarboxylic diimide molecules discontinuously onto base p-type pentacene thin films (the formation of the discontinuous pn-heterojunction), a positive shift of the threshold voltage was attained which enabled realizing a depletion-mode transistor from an original enhancement-mode pristine pentacene transistor. Careful control of the threshold voltage based on this method led assembling a depletion-load inverter comprising a depletion-mode transistor and an enhancement-mode transistor connected in series that yielded tunable signal inversion voltage approaching 0 V. In addition, the tunability could be applied to improve the program/erase signal ratio for non-volatile transistor memories by more than 4 orders of magnitude compared to reference memory devices made of pristine pentacene transistors.     

小波不变矩的低空风切变识别

针对微下击暴流、低空急流、顺逆风以及侧风低空风切变样本图像间的形状特性关系,主要研究了小波不变矩的特征提取技术在风切变识别中的应用.首先,采用基于三次B样条的小波不变矩提取风切变图像的形状特征.然后,将提取的特征通过Fisher线性判别分析(LDA)降低维数,实现风切变有效特征的提取.最后,采用三阶近邻分类器分类识别四种低空风切变.实验结果表明,该算法与应用Hu矩和Zernike矩特征进行分类识别相比,识别结果更加稳定,且平均识别率得到了较大提高,能够有效用于风切变图像的类型识别中.     

Al-Zn-Mg-Cu合金多尺度第二相粒子与性能关系研究

介绍了Al-Zn-Mg-Cu合金多尺度第二相粒子与性能关系的研究。涉及的多尺度第二相粒子包括微米尺度的金属间化合物、亚微米尺度的弥散相、纳米尺度的晶内析出相和晶界析出相;涉及的相关性能为强度、断裂韧性以及腐蚀性能。结合相关文献与作者的研究工作,可以得出以下结论:金属间化合物会影响合金的断裂韧性和腐蚀抗力;弥散相通过抑制基体再结晶的方式影响合金的强度、断裂韧性以及腐蚀抗力;晶界析出相会影响合金的断裂韧性和腐蚀抗力;晶内析出相影响合金的强度和断裂韧性。     

纳米结构镁的制备及其储氢性的研究进展

氢能的利用越来越受到人们的重视,而氢的储存和运输限制了其广泛的实际应用。镁基合金作为一种固体储氢材料,在储氢领域显示出巨大的潜力。但是,吸放氢温度高,释氢速率慢,阻碍了其工程应用。为了提高镁基合金的储氢能力,目前的研究主要集中在合金成分的优化和加工工艺的改进方面,而纳米细化是最有前途的方法之一。详细介绍了纳米镁的各种制备工艺,包括高能球磨、物理气相沉积、氢化化学气相沉积、液相化学合成和模板法,并分析了各种方法的优缺点。阐述了纳米结构和元素掺杂对镁基合金储氢性能的影响。本研究为储氢领域的材料开发和制备工艺的改进提供参考。     

CoCrFeNi高熵合金在金属氧化物熔盐电脱氧中的形成过程

在1173 K下将金属氧化物在CaCl₂熔盐中进行电脱氧,制备了CoCrFeNi高熵合金。通过X射线衍射（XRD）、扫描电子显微镜（SEM）和能量色散X射线能谱（EDS）研究了不同电解时间下金属氧化物转化为高熵合金的相变过程。结果表明,CoCrFeNi高熵合金的形成过程包括快速脱氧和深度脱氧2个阶段。在快速脱氧阶段,在1 h内去除了烧结氧化物球团中93.93%（质量分数）的氧,电流效率达到89.95%。电解结束后,产物的氧含量可达0.26%（质量分数）,电流效率为17.93%。该高熵合金的形成过程可用于指导建立低成本、高效率的电化学路线。     

高熵合金抗高温氧化机理研究展望

近年来高熵合金因具有许多优于传统合金的性能备受瞩目,而高温氧化问题大大限制了其发展应用。多元组成使高熵合金的高温氧化过程不同于单一金属,不同氧化阶段的动力学规律有很大不同。氧化前期多种元素发生氧化反应,氧化物种类和氧化膜结构随时间发生变化,直到稳定氧化阶段氧化产物才固定存在。本文从初期选择性氧化、过渡态氧化和稳定氧化期3个阶段深入剖析高熵合金高温氧化各个过程的详细机理,并总结相应的改善高温抗氧化性能的方法,为高熵合金材料设计和性能调控提供重要的理论依据。     

Nb−Si基超高温合金在900℃下的氧化和热腐蚀行为

对Nb?Si基超高温合金在900℃下的氧化和热腐蚀行为进行研究。结果表明:合金的氧化和热腐蚀动力学均由初始的抛物线增长阶段和随后的线性快速增长阶段组成。在氧化的初始阶段(1~50 h),合金表面形成较薄且连续的氧化膜,而在随后的线性阶段,合金表面发生严重的“粉化”现象。合金经热腐蚀后,其线性增长阶段发生得更早,同时在热腐蚀20~100 h后发生灾难性的氧化膜剥落现象,表明熔盐(Na2SO4和NaCl)能显著加快合金的氧化过程。STEM结果显示,热腐蚀后的氧化膜主要由TiO2、Nb2O5、TiNb2O7、非晶硅酸盐和NaNbO3组成。