边失效概率不同情况下网络全终端可靠度的近似计算

用可靠性多项式计算网络全终端可靠度是评估网络拓扑结构德定程度的重要依据,精确计算可靠性多项式是一个NP-hard问题.本文通过对基于产生孤立点的概率随机事件的定义,运用概率不等式变换,给出了点可靠、边以不同的概率相互独立失效时,网络全终端可靠度的上界表达式,在可靠度近似计算过程中避免了对网络边割集和路集的搜索.最后,在...     

Spectral analysis of photo-induced delayed luminescence from mesenchymal stem cells for label-free cell viability assessment

In this work, the spectral properties of the photo-induced delayed luminescence (DL) from mesenchymal stem cells (MSCs) and their correlation with cell viability were investigated using the single photon counting combined with band-pass filters. The results show that the DL of MSCs has a broad spectral distribution, which covers from 300 nm to 650 nm at least. The DL spectrum is not evenly distributed, but mainly distributed in the range from 400 nm to 550 nm. In addition, the DL spectral distribution remains stable during the DL decay process. Compared with the DL spectra of MSCs with high viability (>80%), those of MSCs with low viability (<30%) show a significant red-shift, referring to the increase in the proportion of 572—650 nm band and the decrease in the proportions of both 315—436 nm band and 413—500 nm band. Furthermore, the degree of the DL spectral red-shift exhibits a monotonous change as MSCs’ viability decreases, and thus can be used as an important indicator for the cell viability assessment.     

路由选择的智能方法

本文利用模糊理论来对通信网中的路由进行动态选择。文中首先讨论了路由选择所要考虑的一些因素,然后利用模糊综合评判理论评估出路由选择的量化综合指标,再通过模糊图中的最强路法选择出两点间的最佳路由。最后把该法同已有方法进行仿真比较,发现该法比较的方法能较大地提高接通率,且性能未受损害。     

Performance and reliability comparison between asymmetric andsymmetric LDD devices and logic gates

The performance and reliability of NMOSFET asymmetric lightly doped drain (LDD) devices (with no LDD on the source side) are compared with those of conventional LDD devices. At a fixed V_dd, asymmetric LDD devices exhibit higher I_dsat and shorter hot-carrier lifetime. To maintain the same hot-carrier lifetime, asymmetric LDD devices must operate at lower V_dd while higher I_dsat is retained. For the same hot-carrier lifetime, ring oscillators with NMOSFET asymmetric LDD devices can achieve 5% (10% if PMOSFET also had asymmetric LDD) higher speed and 10% lower power. The hot-carrier reliability of inverter, NAND, and NOR structures with asymmetric and conventional LDD devices is also simulated and compared     

LIGA技术制作Fresnel波带片的研究

简要介绍了利用ＬＩＧＡ技术中同步辐射光刻、微电铸技术制作α粒子编码成像波带片的研究,讨论了编码波带片的结构和影响波带片的平面和层析分辨率的参数。根据实验要求设计和研制了一种α粒子编码成像波带片。     

横流CO2激光器的折叠式谐振腔研究

在横流ＣＯ２激光器中折叠式谐振腔,不仅能改善光束质量,而且有提高转换效率。文章地折叠式谐振腔的折数确定,转折镜的选择,谐振腔的总体结构进行了分析研究,并设计了一种七折光学折叠腔,在大功率横流激光器上取得了良好的实验效果,获得了千瓦级基模激光输出。     

TEOS LPCVD技术在SiC功率器件工艺中的应用

应用正硅酸乙酯(TEOS)LPCVD技术实现二氧化硅在SiC晶片表面的淀积,在一定程度上弥补了SiC氧化层过薄和PECVD二氧化硅层过于疏松的弊端。采用TEOS LPCVD技术与高温氧化技术的合理运用,既保证了氧化层介质的致密性和与SiC晶片的粘附能力,又提高了器件的电性能和成品率,同时避免了为获得一定厚度氧化层长时间高温氧化的不足。采用此技术后,SiC芯片的直流成品率得到提高,微波功率器件的对比流片结果显示微波性能也得到了明显的提升,功率增益比原工艺提高了1.5 dB左右,功率附加效率提升了近10%。     

Salt‐Assisted Synthesis of 2D Materials

2D materials have demonstrated good chemical, optical, electrical, and magnetic characteristics, and offer great potential in numerous applications. Corresponding synthesis technologies of 2D materials that are high‐quality, high‐yield, low‐cost, and time‐saving are highly desired. Salt‐assisted methods are emerging technologies that can meet these requirements for the fabrication of 2D materials. Herein, the recent process for the salt‐assisted synthesis of 2D materials and their typical applications are summarized. First, the properties of salt crystals and molten salts are briefly introduced, and then some examples of 2D materials synthesis with the assistance of salt as well as their representative applications are presented. The underlying mechanisms of salts with different states on the formation of 2D morphology are discussed to aid in the rational design of synthetic route of 2D materials. At last, the challenges and future perspectives for salt‐assisted methods are briefly described. This review provides guidance for the controllable synthesis of 2D materials based on the salt‐assisted approaches.     

Covalent 0D–2D Heterostructuring of Co9S8–MoS2 for Enhanced Hydrogen Evolution in All pH Electrolytes

Ultrasmall Co₉S₈ nanoparticles are introduced on the basal plane of MoS₂ to fabricate a covalent 0D–2D heterostructure that enhances the hydrogen evolution reaction (HER) activity of electrochemical water splitting. In the heterostructure, separate phases of Co₉S₈ and MoS₂ are formed, but they are connected by Co–S–Mo type covalent bonds. The charge redistribution from Co to Mo occurring at the interface enhances the electron‐doped characteristics of MoS₂ to generate electron‐rich Mo atoms. Besides, reductive annealing during the synthesis forms S defects that activates adjacent Mo atoms for further enhanced HER activity as elucidated by the density functional theory (DFT) calculation. Eventually, the covalent Co₉S₈–MoS₂ heterostructure shows amplified HER activity as well as stability in all pH electrolytes. The synergistic effect is pronounced when the heterostructure is coupled with a porous Ni foam (NF) support to form Co₉S₈–MoS₂/NF that displays superior performance to those of the state‐of‐the‐art non‐noble metal electrocatalysts, and even outperforms a commercial Pt/C catalyst in a practically meaningful, high current density region in alkaline (>170 mA cm^?2) and neutral (>60 mA cm^?2) media. The high HER performance and stability of Co₉S₈–MoS₂ heterostructure make it a promising pH universal alternative to expensive Pt‐based electrocatalysts for practical water electrolyzers.     

碳纳米管非对称接触结构制作及电学性能研究

实验研究了多根或单根单壁碳纳米管与非对称金属电极接触结构的制作方法。先用介电泳方法(DEP)将碳纳米管定向排列在Au电极对之间,再用电子束光刻(EBL)在碳纳米管的一端加工Al电极,获得多根碳纳米管与金铝电极的非对称接触结构。先用EBL在Au电极对一端覆盖Al电极,再用DEP排列碳纳米管,实现单根碳管与金铝电极的非对称接触结构。非对称结构器件的电学测试研究表明,器件的I-V曲线不再对称,呈现出整流特性。