Organization, autonomy, and success of internationally dispersedR&D facilities

The organization and autonomy of internationally dispersed R&D facilities and their influence on the success of R&D are analyzed from the point of view of their headquarters. It is shown that different organizational structures for internationally dispersed R&D are connected with specific degrees of autonomy. The three classical success factors-timing, performance, and budgeting-for measuring project success can be identified. Although quite a few R&D facilities are left with a high degree of autonomy, these units are not perceived, with respect to these success factors, to be as successful as those facilities with a lower degree of autonomy and a low degree of centralization     

Packet loss visibility across SD,HD, 3D,and UHD video streams

The trend towards video streaming with increased spatial resolutions and dimensions, SD, HD, 3D, and 4kUHD, even for portable devices has important implications for displayed video quality. There is an interplay between packetization, packet loss visibility, choice of codec, and viewing conditions, which implies that prior studies at lower resolutions may not be as relevant. This paper presents two sets of experiments, the one at a Variable BitRate (VBR) and the other at a Constant BitRate (CBR), which highlight different aspects of the interpretation. The latter experiments also compare and contrast encoding with either an H.264 or an High Efficiency Video Coding (HEVC) codec, with all results recorded as objective Mean Opinion Score (MOS). The video quality assessments will be of interest to those considering: the bitrates and expected quality in error-prone environments; or, in fact, whether to use a reliable transport protocol to prevent all errors, at a cost in jitter and latency, rather than tolerate low levels of packet errors.     

三维集成

在封装的舞台上,三维集成技术因为在提高电子系统的性能和微型化方面效果卓著而引起重视。目前三维技术的手段一般采用较长的焊线来连接堆叠芯片和基层。新的三维概念仍处在开发阶段,但它将提供更短的互联,更高的互联密度,更低的成本。对于不同的应用,需要有相应且适宜的3D技术。     

0D, 1D,and 2D Supramolecular Nanoassemblies of a Porphyrin: Controllable Assembly,and Dimensionality-Dependent Catalytic Performances

While tremendous advances have been made in dimensionality-dependent performances of inorganic-based low-dimensional nanostructures, paradigms concerning π-conjugated molecule-based supramolecular nanoassemblies are relatively fewer despite their various intrinsic advantages. It is herein reported that 0D, 1D, and 2D supramolecular nanostructures of a porphyrin, 5,10,15,20-tetrakis(4-aminophenyl)-21H,23H-porphine, with a spherical, fibrous and sheetlike architecture, respectively, could be fabricated via a reprecipitation protocol. As a typical example to demonstrate their dimensionality-dependent optoelectronic performances, it is shown that the nanomaterials could serve as photocatalysts for water remediation, where the catalytic reactivity exhibits a trend of nanofibers > nanospheres > nanosheets. The superior catalytic reactivity of the nanofibers stems from the formation of relatively well-defined J-aggregates with orderly and tightly organized chromophores, conferring them with strong photoinduced electron–hole transport and separation capability. The higher catalytic reactivity of the nanospheres than nanosheets results from their larger specific surface area, which facilitates efficient accessibility of photogenerated charge carriers, although the porphyrins therein form unspecific J-aggregates with disorderly and loosely stacked chromophores. The investigation likely initiates a simple method for π-conjugated molecule-based 0D, 1D and 2D nanoassemblies by using the same tectons, based on which the highlighted underlying scientific insights might provide useful clues for rational design of organic-based low-dimensional advanced soft materials.     

应用二维激光雷达的地形识别系统设计

动力型下肢假肢的主要功能是帮助截肢患者实现独立自如的行走,为了使假肢能够配合用户的运动,需要对用户的运动意图进行识别。通过提前获知用户前方环境信息,将其作为运动意图识别的先验知识,可以提高运动意图的识别精度。为了给动力型下肢假肢提供前方环境信息,设计了一种可穿戴的地形识别系统。首先通过安装在人体腰部的二维激光雷达收集前方地形数据,然后利用凝聚分层聚类算法对采集的数据进行线性特征提取,最后利用有限状态自动机对前方地形进行识别。实验中,对平地过渡到上/下斜坡、上/下楼梯四种地形进行了测试。结果表明,该系统不仅对四种地形的识别精度达到了95.8%,还可以计算出传统的运动意图识别方法无法得到的地形参数信息,包括斜坡的坡度、楼梯的阶数和台阶的高度与宽度。这证明了将该系统应用于动力型下肢假肢的有效性和可行性。     

Siloxene,Germanane, and Methylgermanane: Functionalized 2D Materials of Group 14 for Electrochemical Applications

2D monoelemental group 14 materials beyond graphene, such as silicene and germanene, have recently gained a lot of attention. Covalent functionalization of group 14 layered materials can lead to significant tuning of their properties. While optical and electronic properties of germanene, silicene, and their derivatives have been studied in detail previously, there is no information on their electrochemistry and toxicity. Herein, electrochemical applications of 2D siloxene, germanane, and methylgermanane, specifically for detection of an important biomarker, dopamine, as well as catalyzation of oxygen reduction and hydrogen evolution reactions, which are important in energy applications, are explored. Among the three materials, germanane portrays most superior properties for the electrochemical applications mentioned. All three materials possess fast heterogeneous electron transfer rates, relative to bare glassy carbon electrodes. In addition, toxicity studies of these materials are conducted to gain insights on their possible harmful effects toward human health. The results of this study show siloxene nontoxic while germanane and methylgermanane impose dose‐dependent toxicity. Interestingly, methylation successfully reduce the toxicity of methylgermanane at lower concentrations. These studies provide fundamental insights into electrochemical and toxic properties of functionalized group 14 layered materials for future electrochemical applications.     

面向5G通信网的D2D技术综述

在探讨D2D对通信技术未来发展的导向作用基础上,明确了影响D2D系统设计的多个因素,即D2D设备发现、资源分配、缓存技术、D2D-MIMO。从而勾画出基于D2D技术的光纤前传和软件定义网络实现数据/控制分离的扁平化5G架构,提出负责接入的下层宏/小基站蜂窝网和负责管理的上层网络云的管理机制。将D2D技术、SDN技术、边缘计算和物联网技术等关键技术引入未来移动通信网络已经成为研究领域的热点,针对与之相关的、未来大规模网络的移动性、QoS和大数据特性进行了讨论。     

1D/2D Nanomaterials Synergistic,Compressible, and Response Rapidly 3D Graphene Aerogel for Piezoresistive Sensor

Graphene‐based aerogels have been widely studied for their high porosity, good compressibility, and electrical conductivity as piezoresistive sensors. However, the fabrication of graphene aerogel sensors with good mechanical properties and excellent sensing properties simultaneously remains a challenge. Therefore, in this study, a novel nanofiber reinforced graphene aerogel (aPANF/GA) which has a 3D interconnected hierarchical microstructure with surface‐treated PAN nanofiber as a support scaffold throughout the entire graphene network is designed. This 3D interconnected microporous aPANF/GA aerogel combines an excellent compressive stress of 43.50 kPa and a high piezoresistive sensitivity of 28.62 kPa^?1 as well as a wide range (0–14 kPa) linear sensitivity. When aPANF/GA is used as a piezoresistive sensor, the compression resilience is excellent, the response time is fast at about 37 ms at 3 Pa, and the structural stability and sensing durability are good after 2600 cycles. Indeed, the current signal value is 91.57% of the initial signal value at 20% compressive strain. Furthermore, the assembled sensors can monitor the real time movement of throat, wrist pulse, fingers, wrist, and knee joints of the human body at good sensitivity. These excellent features enable potential applications in health detection.     

一种新的多值A/D转换器

通过对三值 A/ D转换数学表示的分析 ,设计了二种三值 A/ D转换器电路。该转换器电路具有结构简单、低功耗、小型化和高信息密度等优点 ,它可进一步完善多值数字系统的研究     

一种新的二维角度估计的高分辨算法

该文针对常规2维波达方向估计的高分辨算法运算量大和稳健性差等问题,提出了一种新的2维角度估计的高分辨方法。该方法首先建立基于范数约束的最优化问题的目标函数;然后用迭代算法沿均匀面阵接收数据的方位向求最小化目标函数的稀疏解,得到方位、俯仰角耦合的空间角频率,并分离信号;最后对每个分离的信号,沿面阵俯仰向求稀疏解,得到信号的俯仰角,进而求得对应的方位角。针对算法存在测角盲区的问题,提出了一种改进方法,通过求解空间2维稀疏解得到信号的2维角度。与传统的高分辨算法相比,该方法对信噪比和快拍数要求不高、无需特征值分解和多维搜索过程,具有较高的分辨力和极低的旁瓣电平。     

Resource Allocation Schemes in D2D Communications: Overview,Classification, and Challenges

Device-to-Device (D2D) communications is predicted to be a major part of 5G wireless communications due to its benefits such as flexible connectivity and unloading of traffic burden off the cellular networks. However, interference scenarios in D2D communications are usually more complicated than conventional wireless communications, e.g., spectrum reuse is commonly involved in D2D communications, especially when it works as an underlay. Therefore, how to coordinate the challenges of significant interference with the demand of higher data rates under the constraints of efficient energy consumption and spectrum utilization has become a haunting problem in our way to the ideal performance of wireless communications system. The solution resides in multiple resource allocation techniques in D2D communications as each of them attempts to solve or optimize one or several essential elements in the system. In this paper, a survey of resource allocation schemes in D2D communications is presented. We discuss the optimization classification including objectives, constraints, problem types and solutions. This paper also highlights system characteristics. Finally, future research challenges are outlined.     

A 3D interpolation method for base-station-antenna radiationpatterns

A simple method for the estimation of three-dimensional radiation patterns from the horizontal and vertical cuts is presented, which leads to lower errors compared to some common methods. In order to evaluate its reliability, the method has been tested for various theoretical cases by considering dipoles, individually or in arrays. For the case of the half-wavelength dipole, a maximum error of 12.0 dB (for directions of very low radiation) and an average error of 1.6 dB were obtained; for a uniform array of two dipoles radiating in a half-plane (which leads to a similar GSM panel-antenna's radiation pattern), the average error was 1.8 dB (on the whole sphere). Measurements were also conducted in a real GSM network, and different approximations for the base-station radiation pattern were compared. The method presented here leads to a lower error, its average absolute value being 4.0 dB. This interpolation method is very useful for incorporating full three-dimensional radiation patterns into mobile-communications planning tools     

Study on adaptive modulation in D2D communications over Nakagami-m fading channel

A novel adaptive modulation based on nondata-aided error vector magnitude (NDA-EVM) was proposed to solve the problem of lower spectral efficiency in device to device (D2D) communication over Nakagami-m fading channel.The NDA-EVM was used to evaluate the channel quality.The relationship between NDA-EVM and symbol error ratio (SER) was derived according to the maximum likelihood method.Thereafter,the adaptive modulation mechanism of MQAM with the SER constraint was designed.Considering the joint effect of finite-length queuing and fading channel,the system packet loss rate and spectral efficiency was analyzed.Theoretical analysis and simulation experiments show that NDA-EVM based adaptive modulation accurately gives the modulation threshold and evaluates the relationship between QoS and packet loss rate,the proposed algorithm improves system spectral efficiency while maintaining low algorithm complexity,spectral efficiency improves by 0.752 bit·(s·Hz)^-1,compared with traditional algorithm.     

Terfenol-D对层状材料PVDF/Terfenol-D/PZT的特性影响

采用热压法制备了中间层为聚偏氟乙烯(PVDF)/Tb-Dy-Fe合金(Terfenol-D)/锆钛酸铅(PZT),上、下层为PVDF/Terfenol-D的层状复合结构材料,研究了中间层Terfenol-D不同体积含量变化对样品介电常数、介电损耗、压电常数以及磁电耦合系数的影响规律。研究发现,在中间层的φ(Terfenol-D)=4%时,综合性能最优,其中压电系数d33为32.4pC/N,磁电耦合系数αE为1 118mV/A。     

Germanium pMOSFETs with Schottky-barrier germanide S/D, high-/spl kappa/ gate dielectric and metal gate

Schottky-barrier source/drain (S/D) germanium p-channel MOSFETs are demonstrated for the first time with HfAlO gate dielectric, HfN-TaN metal gate and self-aligned NiGe S/D. The drain drivability is improved over the silicon counterpart with PtSi S/D by as much as /spl sim/5 times due to the lower hole Schottky barrier of the NiGe-Ge contact than that of PtSi-Si contact as well as the higher mobility of Ge channel than that of Si.     

Explicit bounds to R(D) for a binary symmetric Markov source

A new upper houndR_{u}(D)and lower houndR_{ell}(D)are developed for the rate-distortion function of a binary symmetric Markov source with respect to the frequency of error criterion. Both hounds are explicit in the sense that they do not depend on a blocklength parameter. In the intervalD_{c} < D < 1/2 = D_{max}, whereD_{c}is Gray's critical value of distortion,R_{u}(D)is convex downward and possesses the correct value and the correct slope at both endpoints. The new lower boundR_{ell}(D)diverges from the Shannon lower bound at the same value of distortion as does the second-order Wyner-Ziv lower bound. However, it remains strictly positive for allD leq 1/2and therefore eventually rises above all the Wyner-Ziv lower bounds asDapproaches1/2. Some generalizations suggested by the analytical and geometrical techniques employed to deriveR_{u}(D)andR_{ell}(D)are discussed.     

一种有效的3D存储器内建自修复方案

与2D存储器相比,3D存储器能够提供更大的容量、更高的带宽、更低的延迟和功耗,但成品率低。为了解决这个问题,提出一种有效的3D存储器内建自修复方案。将存储阵列的每一行或每一列划分成几个行块或列块,在不同层的行块或列块之间进行故障单元的映射,使不同层同一行或同一列的故障在逻辑上映射到同一层中,从而使一个冗余行或冗余列能够修复更多的故障,大大增加了冗余资源利用率和故障修复率。实验结果表明,与其他修复方案相比,该方案的修复率更高,实现相同修复率所需的冗余资源更少,增加的面积开销几乎可忽略不计。     

高性能三维小波视频编码方法

讨论并实现了基于３Ｄ－ＳＰＩＨＴ算法的三维小波视频编码方法。该方法建立在真三维小波分解基础上，通过定义一种新的时空方向树结构，实现了静止图像ＳＰＩＨＴ算法的三维扩展。该方法不涉及运动估计，具有较低的计算负荷和时间延迟，所产生的视频流是完全嵌入的。实验结果表明该方法能够快速地、高质量地压缩视频图像，是一种很有潜力的视频编码方法。     

Bioinspired Nanocomposites: Ordered 2D Materials Within a 3D Lattice

Composites, materials composed of two or more materials—metallic, organic, or inorganic—usually exhibit the combined physical properties of their component materials. The result is a material that is superior to conventional monolithic materials. Advanced composites are used in a variety of industrial applications and therefore attract much scientific interest. Here the formation of novel carbon‐based nanocomposites is described via incorporation of graphene oxide (GO) into the crystal lattice of single crystals of calcite. Incorporation of a 2D organic material into single‐crystal lattices has never before been reported. To characterize the resulting nanocomposites, high‐resolution synchrotron powder X‐ray diffraction, electron microscopy, transmission electron microscopy, fluorescence microscopy and nanoindentation tests are employed. A detailed analysis reveals a layered distribution of GO sheets incorporated within the calcite host. Moreover, the optical and mechanical properties of the calcite host are altered when a carbon‐based nanomaterial is introduced into its lattice. Compared to pure calcite, the composite GO/calcite crystals exhibits lower elastic modulus and higher hardness. The results of this study show that the incorporation of a 2D material within a 3D crystal lattice is not only feasible but also can lead to the formation of hybrid crystals exhibiting new properties.     

Nano-graphoepitaxy of semiconductors for 3D integration

The advantages of integrating semiconductor devices at more than one level (‘3D integration’) are now recognized. Key to achieving monolithic 3DICs is the ability to form single crystal semiconductor islands at the upper level without unduly heating the lower level structures. In prior work a surface relief grating of 3.8 μm pitch in the substrate was used to mediate single crystal formation while continuous wave (CW) heating a thin film of amorphous silicon; the term ‘graphoepitaxy’ was coined. CW heating is not possible in our case because it would overheat the lower layers. Moreover the area of the crystallites need only be about 100 nm to accommodate today’s transistors. Thus we have chosen a substrate grating pitch of 190 nm (hence the term ‘nano-graphoepitaxy’) and a modulated CW laser to reduce the heating time to several μs. Preliminary results indicate the substrate grating lines can indeed determine the position of the crystallite boundaries when the film thickness is 100 nm; the effect is much less pronounced in 500 nm thick films.