Thin-film transistors based on liquid-crystalline tetrafluorophenylter thiophene derivatives: thin-film structure and carrier transport

The authors fabricated thin films by solution processes using liquid-crystalline (LC) semiconductors, 5-alkyl-5’’-(4-hexyltetrafluorophenyl)-2,2’:5’,2’’-terthiophene (2–5). Films of 5-propyl-5’’-(4-hexyltetrafluorophenyl)-2,2’:5’,2’’-terthiophene (2) show similar molecular packing as their non-fluorinated counterparts. However, the degree of molecular packing ordering from X-ray diffraction measurement is higher, and the films exhibit a more crystal-like structure. Moreover, fluorination has a remarkable effect on their mesomorphic behaviors. Films of 2 consist of large size LC domains (in the range of 100 μm) at room temperature. Thin-film transistors (TFTs) of 2 show p-type operation with good hole mobility up to 0.027 cm²/Vs as well as improved operation stability under ambient conditions and high on/off ratio. Tetrafluorophenyl substitution leads to lowering of HOMO energy by 0.15 eV for 2 and 0.35 eV for 5, resulting in operation stability. Variable-temperature current-voltage measurements indicate intrinsic carrier transport in films of 2.     

融合链接拓扑结构和用户兴趣的朋友推荐方法

提出一种新的朋友推荐方法,该方法同时使用用户兴趣和朋友关系这2种因素来为目标用户推荐朋友,对PageRank算法进行改进,提出一种能同时融合上述2种因素的Topic_Friend_PageRank(TFPR)模型。首先,采用LDA(latent Dirichlet allocation)分析用户发布的消息内容,将用户表示为若干主题上的分布,从而建模用户的兴趣。接下来,使用加权的PageRank算法建模用户在整个链接拓扑中的重要程度和用户之间朋友关系的相似性。最后根据主题感知的PageRank思想,将用户兴趣融入前面提到的加权PageRank中,形成同时融合用户兴趣和朋友关系的TFPR模型。采用新浪微博数据验证所提模型的性能,实验证明该模型能同时得到较高的准确率和召回率。     

Image postprocessing by Non-local Kuan’s filter

Blocking artifacts exist in images and video sequences compressed to low bit rates using block-based discrete cosine transform (DCT) compression standards. In order to reduce blocking artifacts, two image postprocessing techniques, DNLK filter and OCDNLK filter, are presented in this paper. A more accurate DCT domain Kuan’s filter based on Non-local parameter estimation was proposed from the linear minimum mean-square-error (MMSE) criterion. We analyze the required two assumptions for the filter theoretically. Then the DCT domain Kuan’s filter for low frequency coefficients and Non-local mean filter for high frequency AC coefficients constitute the proposed Non-local Kuan’s (NLK) filter. After that, we propose the Dual Non-local Kuan’s (DNLK) filter by applying the proposed filter in dual layer. The DNLK filter is extended to form the Overcomplete Dual Non-local Kuan’s (OCDNLK) filter by applying to the overcomplete DCT coefficients. Experimental results on coded images using test quantization tables and JPEG coded images show the effectiveness of the two methods.     

可编程逻辑器件的历程与发展

可编程逻辑器件逐渐成为微电子技术发展的主要方向,文章概述了可编程逻辑器件（PLD）的分类、发展历史与发展现状。现场可编程门阵列（FPGA）和复杂可编程逻辑器件（CPLD）是可编程逻辑器件技术按其内部结构不同延伸出的两个分支,文中讨论了它们各自的优缺点,并对它们作了比较。文中特别介绍了FPGA产品的主要生产厂家,以及四大厂家各自产品的应用领域,分别给出了Xilinx公司和ALTERA公司FPGA产品的谱图,最后展望了FPGA产品的未来发展趋势。     

基板支撑梢对TFT栅界面SiN_x和a-Si成膜特性的影响

采用等离子体增强化学气相沉积法(PECVD)制得氮化硅和氢化非晶硅薄膜,对PECVD设备中基板支撑梢区域的膜质进行了研究。结果显示基板支撑梢对氮化硅薄膜的影响是:基板支撑梢区域的膜厚(沉积速率)高于非基板支撑梢区域,氢含量及[SiH/NH]值高于非基板支撑梢;对氢化非晶硅薄膜的影响是:基板支撑梢区域的膜厚(沉积速率)小于非基板支撑梢区域,氢含量高于非基板支撑梢。并对成膜影响的机理进行了分析讨论。     

Thumbs up: A thematic analysis of image-based posting and liking behaviour on social media

This study aimed to investigate the thoughts that social media users have prior to posting or ‘liking’ images on social media; particularly exploring the presence of egoistic, self-presentation considerations. Responses to two open-ended questions regarding considerations prior to posting (n?=?203) and ‘liking’ (n?=?195) images on social media were analysed using thematic analysis. Egoistic motivations influenced both posting and ‘liking’ an image on social media; suggesting an awareness that self-presentation can be affected (and therefore manipulated) through image posting and ‘liking’. Users also considered who would see their content or behaviour, and the effect this might have on others. Finally, ‘liking’ actually represents liking, with enjoyment and image value considered prior to providing public, online appreciation.     

影响PSM工艺产品良率因素的研究

文章围绕实际工作中遇到的0.13μm Logic产品的良率问题展开。主要通过分析比较相位移掩膜工艺和传统铬膜工艺的优缺点,找出可能导致产品良率低的主要因素。最后集中分析光阻膜厚与关键尺寸大小的关系图。当关键尺寸小到0.13μm以下时,前层图形的影响对光阻膜厚的选择至关重要,进而对良率也有相应的影响。通过针对光阻膜厚的选择建立理论模型,并设计相关实验进行验证,最后得到结论。在研究过程中会用到一些与光刻相关的先进机器设备和软件。硬件方面包括光阻涂布和显影机、扫描式曝光机、关键尺寸量测机、显影后检查硅片表面宏观缺陷的机器、检查硅片表面微观缺陷的机器等等,软件方面包括设计尺寸的检查软件、光学邻近效应修正软件等。     

Separation of dynamic current-voltage characteristics (DCVCs) of an oxide film from the DCVC of ionic currents in a metal/oxide/semiconductor structure: Universal quasi-static DCVCs of a film

Analytic results for a quasi-equilibrium distribution of mobile ions in an oxide film contained in a metal/oxide/semiconductor (MOS) structure, as well as formulas for the concentration of ions at the center of the film and on its boundary and formulas for the ionic centroid, are reviewed. Thresholds for the emergence of a U-shaped distribution of ions with characteristic accumulation of ions near the film’s boundary (segregation of ions) are analyzed; the case of a half-space is considered as well. A method to determine the dynamic current-voltage characteristic (DCVC) of the film’s ionic currents is proposed. This method uses an experimental DCVC of the entire structure and a quasi-equilibrium (low-frequency) electronic voltage-capacitance characteristic of the structure. The film’s DCVC has to be separated to eliminate masking effects of the semiconductor’s capacitance on the structure’s DCVC. An analytic method for calculation of the film’s quasi-static DCVC is developed for a model of a homogeneous film. When expressed in dimensionless units, such DCVCs, which are shown to depend on only the dimensionless concentration of ions in the film (per unit area), prove to be universal functions. The population of ionic traps on the film’s boundary is described using the energy Gibbs distribution of ions. The presence of traps is shown to result in the emergence of an additional “trap” peak on the film’s DCVC only if the concentration of traps is low; when this concentration is large, a single peak is observed on the DCVC.     

基于WO_x阻变材料的RRAM电路设计

采用HHNEC0.18μm标准CMOS工艺设计实现了多个1kb容量的阻变存储器电路。针对WOx阻变材料的操作特点,提出了可切换的写电路以及自调节的读参考电路,满足了单极(Unipolar)与双极(Bipolar)兼容操作需求的同时提高了读操作的成功率。引入位线限流模块解决了置位(set)过程需要字线限流的问题,进而可以实现包含‘0’和‘1’多位数据的并行写入。芯片采用高低两种电压设计,同时包含多种阵列尺寸结构的对比测试电路。     

关于抑制大气湍流对鬼成像的影响研究

鬼成像是指由同一个光源发出的两束光,其中一束光称为信号光,通过物体照射在探测器上,另一束光称为闲置光,光路上不包含任何物体,最后对这两束光进行符合计数,通过符合测量可以得到物体的像。本文在基于轨道角动量的量子成像理论基础上,首先介绍大气湍流对成像质量产生的影响,然后采取纠锗编码的方法来抑制湍流的影响。本文用LabView软件进行仿真,由仿真结果表明,采用（7,4）线性分组码之后,成像质量显著提高,有效减小了湍流的影响。     

Why should I pay? Exploring the determinants influencing smartphone users’ intentions to download paid app

The objectives of this study are to investigate (1) the positive effects of smartphone users’ core self-evaluations (CSEs), online consumer conformity, and the social identity of their emotions, (2) the effects of their positive emotions on their trust, and (3) the effects of their trust on their intention to purchase paid apps and willingly engage in co-production. A questionnaire was employed to examine the relationship between the users’ CSEs, online consumer conformity, and social identity, on the one hand, with their intention to purchase paid apps and willingly engage in co-production on the other hand. The findings were as follows: (1) CSE, online consumer conformity, and social identity positively affected the users’ emotions, (2) positive emotions had a significantly positive effect on user trust, and (3) trust had significantly positive effects on the users’ intention to purchase paid apps.     

一种新型IC保护单元ESD评价方式——TLP测试

集成电路的抗ESD能力主要是通过端口的保护结构组合来实现,如何评价保护结构自身的抗ESD能力,被广大的设计人员所越发重视。文章主要介绍一种新型的集成电路ESD保护结构的抗ESD能力测试方式-TLP（传输线测试）测试方式,文章介绍了TLP测试原理、主要的测试机理以及通过测试实例来解释TLP测试方法的优点,该方法能够准确评价每种ESD保护结构的抗ESD水平,为设计人员提供帮助。文章还把TLP并与常用的器件级ESD评价方法做比较,说明两种方法的不同之处以及相互问的关系。     

基于干扰对齐的认知无线电网络中用户性能的优化设计

干扰对齐（IA）是一种新兴的干扰管理技术,被广泛的应用于认知无线电（CR）网络之中,以期消除认知用户（CU）对授权用户（AU）的干扰。然而干扰对齐技术带来了授权用户接收信干噪比（SINR）的下降,使得授权用户的传输速率受到影响。在低信噪比下,授权用户性能无法保证。本文创新性地提出了两种算法设计授权用户预编码滤波器,优化其传输速率,极大地提高了授权用户的性能。同时,为了提高认知用户的性能,本文给出了认知用户的干扰抑制滤波器的优化方案,最大化认知用户的和速率。仿真结果表明,这两种算法都能在一定程度上提高授权用户的传输速率,同时认知用户的传输速率也得以保证。      

冲击噪声背景下基于最小均方归一化误差的波束形成算法

 本文提出一种适用于任意未知统计特性的代数拖尾冲击噪声环境下的MMSNE波束形成算法。算法利用输出信号和参考信号之间的“归一化误差”最小化来求解最优权向量。“归一化误差”定义为接收信号的瞬时自适应无穷范数归一化的形式。与基于最小分数低阶误差波束形成算法相比,MMSNE波束形成算法计算更为简单;不需要噪声特征指数的先验信息或估计;适用于更广的冲击噪声环境;具有更小的估计误差;具有更强的干扰抑制能力。     

MDI训练样本集构建对雷达探测旋翼无人机分类的影响分析

利用卷积神经网络对目标微多普勒特征进行深度学习是目前雷达探测无人机分类的重要手段.实际应用中,无人机参数如叶片转速、叶片长度、叶片初始相位、无人机方位角、无人机俯仰角、无人机径向速度等参数变化大,导致训练样本变化大.该文分析训练样本集对旋翼无人机分类结果的影响.首先建立单旋翼无人直升机、四旋翼无人机和六旋翼无人机雷达回...     

The MBSFN-based eMBMS using the method of Incremental Allocation of Radio Resource between Unicast and Multicast (IARR-UM)

The evolved Multimedia Broadcast Multicast Service (eMBMS) using the Multicast Broadcast Single Frequency Network (MBSFN) technique was designed for having multimedia streaming services using the multicast/broadcast way over the cellular network. Since (1) the unit of resource allocation in eMBMS-MBSFN is a subframe, (2) the code rate of an eMBMS-MBSFN session is based on the lowest Modulation and Coding Scheme (MCS) among involved User Equipments (UEs) of the eMBMS-MBSFN session and (3) the resource allocation for eMBMS-MBSFN cannot be so instantly and dynamically adjusted based on the status of involved UEs, triggering eMBMS-MBSFN in the inappropriate time and allocating inappropriate resource to eMBMS, for which a framework of how to set the configuration of the allocated resource for eMBMS-MBSFN has been defined in the standard, may cause (1) the radio resources to be wasted and (2) the low streaming quality and code rate. Based on the MBMS operation on Demand (MooD) concept, this work proposed the Incremental Allocation of Radio Resource between Unicast and Multicast (IARR-UM) method to dynamically allocate radio resources to eMBMS based on the current Radio Access Network’s (RAN’s) congestion situation such that some suitable multimedia streaming services are switched to eMBMS and others still use unicast communication. To effectively use eMBMS to mitigate RAN’s congestion, the proposed IARR-UM method (1) dynamically increases/decreases the amount of radio resources allocated to eMBMS, i.e., modifying the configuration of the allocated resource for eMBMS-MBSFN using the standard’s framework, based on the situation of RAN’s congestion, (2) uses the Knapsack algorithm to select a subset of suitable multimedia streaming services to be eMBMS sessions according to the given amount of radio resources allocated to eMBMS, and then (3) design a Common Subframe Allocation (CSA) pattern that can have the lower amount of redundant radio resources allocated to eMBMS. The results of the performance evaluation shown that the proposed method can (1) provide UEs with appropriate radio resources and (2), although the throughput may be reduced in some cases, effectively reduce (increase) the UEs’ invalid packet rates (data rates), especially in the higher density of UEs’ situation.

     

Unified alignment of isdn-relevant information communications services/applications through a cubic framework

A cubic (three-dimensional) framework is proposed for mapping various information communications services. The framework implies the important aspect of information technology (IT), or C&C (integration of computers and communications) technology as follows. The first axis is based upon the service classification made for BISDN-relevant services by the CCITT. This ‘communications’ axis covers not only the simple communication, or ‘space-wise information transfer’, but also messaging, retrieval etc. as ‘the combined space/time-wise information transfer’. The second axis represents ‘the multiplicity of media use’ in the human interface of information handling systems. The third axis represents the extent of ‘information processing/conversion’ or the level of computer technology penetration. In the latter part of this paper, the important interrelations between computer communications services and ISDN deployment are discussed using the scope of the above-proposed cubic map. The penetration of PMI (personal machine intelligence) to the same level as telephone set and television set, and the corresponding computer communications services requirements are identified as a fundamental driving force of (N)ISDN deployment.     

云环境下服务信任感知的可信动态级调度方法

以社会学中的人际关系信任模型为基础,提出了一种基于服务消费者的服务满意度评价、推荐者的服务推荐和第三方服务性能反馈的可信度量模型。将用户对服务资源的信任需求和服务资源的可信度并入DLS算法得到可信动态级调度算法CTDLS,从而在计算调度级别时考虑服务资源的可信程度。模拟实验表明,该算法能有效满足任务在信任方面的服务质量需求,对提高任务调度的成功率具有实际意义。     

最小冗余线阵的ES-DOA估计算法研究

采用最小冗余线阵可以显著增大天线的阵列孔径,但其相关矩阵不是Toeplitz矩阵,致使空间平滑解相干等方法失效,限制其在相干信号环境下的使用。结合信号功率估计,采用基于特征空间DOA估计算法,使得在较低信噪比情况下的DOA估计具有很高的精度。该算法同时采用了前后向空间平滑技术,不用减小阵列孔径就可以实现信号去相干。将该算法应用于最小冗余线阵,提高了阵列的DOA估计性能,且不影响阵列孔径。仿真结果证实了该算法的具有较高的精度和较强的鲁棒性。      

Adhesion improvement of Epoxy Molding Compound – Pd Preplated leadframe interface using shaped nickel layers

The weak adhesion between the Epoxy Molding Compound (EMC) and Pd Preplated leadframes (Pd PPF’s) often causes delaminations and reduces the reliability of integrated circuit. This paper reports on a practical method of dramatically improving the adhesion between EMC and Pd PPF’s using electroplating of shaped nickel layers. Button shear tests indicate that the adhesions between the EMC and three different shaped PPF’s are 100%, 160%, 169% higher than that of conventional PPF’s. The mechanical interlocking effect caused by increased surface roughness is the major reason for the improved adhesion as well as for the failure mode transition from adhesive failure to cohesive failure.