Scalable 3D video streaming over P2P networks with playback length changeable chunk segmentation

3D video distribution over P2P networks has been thought as a promising way for 3D video entering home. The convergence of scalable 3D video coding and P2P streaming can provide diverse 3D experiences for heterogeneous clients with high distribution efficiencies. However, the conventional chunk segmentation and scheduling algorithms originally aiming at the non-scalable 2D video streaming are not very efficient for scalable 3D video streaming over P2P networks due to the particular data characteristics of scalable 3D video. Based on this motivation, this paper first presents a playback length changeable 3D video chunk segmentation (PLC3DCS) algorithm to provide different error resilience strengths to video and depth as well as layers with different importance levels in the 3D video transmission. Then, a hybrid-priority based chunk scheduling (HPS) algorithm is proposed to be tied in with the proposed chunk segmentation algorithm to further promote the overall 3D video P2P streaming performance. The simulation results show that the proposed PLC3DCS algorithm with the corresponding HPS can increase the success delivery rates of chunks with more important levels, and further improve the user’s quality of 3D experience.     

定量三维电子显微术及三维电子衍射

用电子晶体学可以确定尺度在微米甚至纳米级晶体的原子结构。它所要求的晶体尺寸比X射线晶体学所需的小百万倍。确定晶体的原子结构既可通过对高分辨电子显微像作图像处理,也可直接用电子衍射数据。同时还可将高分辨电子显微像和电子衍射数据与X射线粉末衍射结合起来确定晶体结构。如果晶体的单胞很大,原子在任何方向上的投影都有重叠,确定晶体的原子结构则需要拍摄一系列不同晶带轴的电子衍射图及高分辨像,再将其综合起来重构晶体的三维静电势图,以得到晶体的原子位置。本文将概括地介绍最近十几年中电子晶体学的一些最新进展及其在无机晶体结构解析方面的一些最新应用实例。     

系统模块(SiP)和三维封装(3D)在移动通讯中的应用

电子封装业界正遭受着前所未有的来自手机和其他移动通讯终端设备挑战。在这一领域里,IC封装的关键是尺寸微型化,缩减成本和市场时机。这一挑战的背后隐含着手机技术发展的两大趋势:系统模块化和日益增长的复杂性及功能。越来越多的功能正在被组合到手机上即PDA、MP3、照相机、互联网等等。功能的增加需要靠模块化来实现,而模块化又促进了更多功能的组合。同时,模块化使得移动通讯终端设备得以微型化、降低成本和缩短设计周期。业界越来越多地感受到整体射频模块和通讯模块解决方案的必要性。这些整体模块把手机设计师从电路设计的细节中解脱出来,从而能专著于高层的手机应用和系统的设计。为了满足上诉移动通讯产品的苛刻要求,大量的新兴电子封装技术和封装产品应运而生。最引人注目的例子在于对系统模块穴SiP雪和三维穴3D雪封装的重点资金和技术投入。这两项先进封装技术有着各自不同的特征和应用范围。总体介绍先进封装技术在移动通讯中的应用,重点讨论电子封装材料和工艺所面临的挑战和最新发展趋势。对移动通讯带来的新一轮集成化及其所产生的潜在供应链问题也做了适当的讨论。     

Dopant,composition and carrier profiling for 3D structures

With the transition from planar to three-dimensional device architectures, devices such as FinFETs, TFETs and nanowires etc. become omnipresent. This requires the dopant atom positioning relative to the gate edges and contacts with controlled 3D distribution, adequate conformality, appropriate concentrations and activation, all of which are important challenges which need to be resolved since they determine the device performance. Developing an appropriate doping technology for the next technology generation requires a concurrent effort in establishing adequate metrology such that appropriate feedback on process steps and the underlying physics can be generated in a timely manner and with sufficient resolution and accuracy. When assessing performance of such metrology tools and concepts for 3D devices and structures, one needs to address not only the ability to achieve 3D spatial resolution, but also the physical property which is probed, i.e. dopants versus carriers, as well as the complexity of the method used because this impacts on success rate, turn-around time, throughput, automation etc. An evaluation in terms of time to data is as important as the technical capabilities.Although techniques with inherently good 3D resolution (e.g. atom probe tomography) might appear to offer the ideal solution for these applications, routine application is still hampered by localization problems during sample preparation, reconstruction artefacts due to inhomogeneous evaporation and differential laser light absorption, limited sensitivity due to the reduced counting statistics, poor tip yield, small throughput, etc. Hence, complementary analysis using 1D methods like secondary ion mass spectrometry (SIMS) are being explored to provide dopant or composition analysis in 3D structures given its high degree of reproducibility, ease of application and industrial acceptance. Targeting carrier profiling in 3D structures and confined volumes as a complement to atom probe (or SIMS) dopant profiles, has led to the extension of scanning probe microscopy (SPM) methods (which are inherently 2D) toward 3D metrology by exploiting either dedicated test structures or through novel approaches such as Scalpel SPM.The application of these SPM methods for 3D structures and confined volumes has demonstrated that the changing surface/volume ratio in confined devices leads to various phenomena (e.g. dopant deactivation, enhanced diffusion,..) which are not observed in blanket sample experiments. More emphasis should therefore be placed on the analysis of devices and structures with the relevant dimensions relative to the exploration of blanket experiments. Thus, the metrology concepts addressed in this paper may be very useful for such investigations.     

Transformable,Freestanding 3D Mesostructures Based on Transient Materials and Mechanical Interlocking

Areas of application that span almost every class of microsystems technology, from electronics to energy storage devices to chemical/biochemical sensors, can benefit from options in engineering designs that exploit 3D micro/nanostructural layouts. Recently developed methods for forming such systems exploit stress release in prestretched elastomer substrates as a driving force for the assembly of 3D functional microdevices from 2D precursors, including those that rely on the most advanced functional materials and device designs. Here, concepts that expand the options in this class of methods are introduced, to include 1) component parts built with physically transient materials to allow triggered transformation of 3D structures into other shapes and 2) mechanical interlocking elements composed of female‐type lugs and male‐type hooks that activate during the assembly process to irreversibly “lock‐in” the 3D shapes. Wireless electronic devices demonstrate the utility of these ideas in functional systems.     

3D Printed Supercapacitor: Techniques,Materials, Designs,and Applications

Supercapacitors (SCs) offer broad possibilities in the rising domain of military and civilian owing to their intrinsic properties of superior power density, long lifetime, and safety features. Despite of low-cost, facile manufacture, and time-saving, 3D printing technology unleashes the potential of SCs in terms of achieving desirable capacitance with high mass loading, fabrication of well-designed complicated structures, and direct construction of on-chip integration systems. In this review, first, the representative printing technologies for SCs and advanced printable materials are scrutinized for SCs and advanced printable materials. Then the structure design principles of electrodes and devices are respectively highlighted and reported cases are systematically summarized. Next, configurations of the SCs and their applications in various areas are described in detail. Finally, the promising research directions for the future are discussed. The perspectives reviewed here are expected to provide a comprehensive understanding of 3D-printed SCs and guidance in realizing their promise in various applications.     

三维卷积神经网络及其在视频理解领域中的应用研究

3维卷积神经网络(3D CNN)是近几年来深度学习研究中的热点,在计算机视觉领域取得了诸多成就。虽然研究多年且成果丰富,但目前仍缺少关于此内容全面、细致的综述。基于此,该文从以下几个方面对其进行综述：首先阐述3维卷积神经网络的基本原理和模型结构,接着从网络结构、网络内部和优化方法总结3维卷积神经网络的相关改进工作,然后对3维卷积神经网络在视频理解领域中的应用进行总结,最后总结全文内容并对未来发展方向进行展望。该文针对3维卷积神经网络的最新研究进展以及在视频理解领域中的应用进行了系统的综述,对3维卷积神经网络的研究发展具有一定的积极意义。     

3D monolithic integration: Technological challenges and electrical results

After a short reminder of the principle of monolithic 3D integration, this paper firstly reviews the main technological challenges associated to this integration and proposes solutions to assess them. Wafer bonding is used to have perfect crystalline quality of the top layer at the wafer scale. Thermally stabilized silicide is developed to use standard salicidation scheme in the bottom layer. Finally a fully depleted SOI low temperature process is demonstrated for top layer processing (overall temperature kept below 650 °C). In a second part the electrical results obtained within this integration scheme are summarized: mixed Ge over Si invertor is demonstrated and electrostatic coupling between top and bottom layer is used to shift the threshold voltage of the top layer. Finally circuit opportunities such as stabilized SRAM or gain in density are investigated.     

3D Printed Actuators: Reversibility,Relaxation, and Ratcheting

Additive manufacturing strives to combine any combination of materials into 3D functional structures and devices, ultimately opening up the possibility of 3D printed machines. It remains difficult to actuate such devices, thus limiting the scope of 3D printed machines to passive devices or necessitating the incorporation of external actuators that are manufactured differently. Here, 3D printed hybrid thermoplast/conducter bilayers are explored, which can be actuated by differential heating caused by externally controllable currents flowing through their conducting faces. The functionality of such actuators is uncovered and it is shown that they allow to 3D print, in one pass, simple flexible robotic structures that propel forward under step‐wise applied voltages. Moreover, exploiting the thermoplasticity of the nonconducting plastic parts at elevated temperatures, it is shown that how strong driving leads to irreversible deformations—a form of 4D printing—which also enlarges the range of linear response of the actuators. Finally, it is shown that how to leverage such thermoplastic relaxations to accumulate plastic deformations and obtain very large deformations by alternatively driving both layers of a bilayer; this is called ratcheting. The strategy is scalable and widely applicable, and opens up a new approach to reversible actuation and irreversible 4D printing of arbitrary structures and machines.     

Cross-layer optimized authentication and error control for wireless 3D medical video streaming over LTE

3D video for tele-medicine applications is gradually gaining momentum since the 3D technology can provide precise location information. However, the weak link for 3D video streaming is the necessary wireless link of the communication system. Neglecting the wireless impairments can severely degrade the performance of 3D video streaming that communicates complex critical medical data. In this paper, we propose systematic methodology for ensuring high performance of the 3D medical video streaming system. First, we present a recursive end-to-end distortion estimation approach for MVC (multiview video coding)-based 3D video streaming over error-prone networks by considering the 3D inter-view prediction. Then, based on the previous model, we develop a cross-layer optimization scheme that considers the LTE wireless physical layer (PHY). In this optimization, the authentication requirements of 3D medical video are also taken into account. The proposed cross-layer optimization approach jointly controls and manages the authentication, video coding quantization of 3D video, and the modulation and channel coding scheme (MCS) of the LTE wireless PHY to minimize the end-to-end video distortion. Experimental results show that the proposed approach can provide superior 3D medical video streaming performance in terms of peak signal-to-noise ratio (PSNR) when compared to state-of-the-art approaches that include joint source-channel optimized streaming with multi-path hash-chaining based-authentication, and also conventional video streaming with single path hash-chaining-based authentication.     

Fine registration of 3D point clouds fusing structural and photometric information using an RGB-D camera

We address the problem of accurate and efficient alignment of 3D point clouds captured by an RGB-D (Kinect-style) camera from different viewpoints. While the Iterative Closest Point (ICP) algorithm has been widely used for dense point cloud matching, it is limited in its ability to produce accurate results in challenging scenarios involving objects that lack structural features and have significant camera view changes. In this paper, we introduce a new cost function with dynamic weights for the ICP algorithm to tackle this problem. It balances the significance of structural and photometric features with dynamically adjusted weights to improve the error minimization process. Our algorithm also includes a novel outlier rejection method, which adopts adaptive thresholding at each ICP iteration, using both the structural information of the object and the spatial distances of sparse SIFT feature pairs. The effectiveness of our proposed approach is demonstrated by experimental results from various challenging scenarios. We obtained superior registration accuracy than related previous methods, at the same time maintaining low computational requirements.     

距离移动电子设备有多远?裸眼3D显示现状与展望

移动电子设备已成为最重要的个人交互平台,具有轻薄型态和低功耗特质的裸眼3D显示亦成为重要研究领域。裸眼3D显示能否应用于移动电子设备,也成为3D显示是否能走进千家万户,影响人类生活习惯的一个重要评判标准。文中主要介绍和比较了与移动电子设备兼容的裸眼三维(3D)显示硬件实现方法和技术,主要包括屏障视差技术、柱透镜阵列技术、时空复用技术、集成成像显示、压缩光场显示和向量光场显示技术。文中进一步分析了现有技术的瓶颈与不足,阐释技术瓶颈的主要产生原因和解决途径,并对裸眼3D显示应用于平板显示的未来发展趋势进行了展望。     

Performance Enhancement of Flexible Piezoelectric Nanogenerator via Doping and Rational 3D Structure Design For Self‐Powered Mechanosensational System

With the rapid development of the Internet of things (IoT), flexible piezoelectric nanogenerators (PENG) have attracted extensive attention for harvesting environmental mechanical energy to power electronics and nanosystems. Herein, porous piezoelectric fillers with samarium/titanium‐doped BiFeO₃ (BFO) are prepared by a freeze‐drying method, and then silicone rubber is filled into the microvoids of the piezoelectric ceramics, forming a unique structure based on silicone rubber matrix with uniformly distributed piezoelectric ceramic. When subjected to external force stimulation, compared with conventional piezocomposite films found on undoped BFO without a porous structure, the PENG possesses higher stress transfer ability and thus boosts output performance. The notable enhancement in the stress transfer ability and piezoelectric potential is proven by COMSOL simulations. The PENG can exhibit a maximum open‐circuit voltage (V_oc) of 16 V and short‐circuit current (I_sc) of 2.8 µA, which is 5.3 and 5.6 times higher than those of conventional piezocomposite films, respectively. The PENG can be used as a triggering signal to control the operation of fire extinguishers and household appliances. This work not only expands the application scope of lead‐free piezoelectric ceramic for energy harvesting, but also provides a novel solution for self‐powered mechanosensation and shows great potential application in IoT.     

3D Printing of Liquid Metals: Recent Advancements and Challenges

The development of flexible electronics (FEs) has rapidly accelerated in numerous fields due to their exceptional deformability, bending, and stretchability. Room-temperature gallium-based liquid metals (LMs) are considered as efficient conductive materials for FEs due to their outstanding electrical conductivity and intrinsic flexibility. Recently, 3D printing has become a promising technique for fabricating FEs. However, the poor printability due to high surface tension and fluidity offers huge challenges in the 3D printing of LMs. This review summarizes the effective strategies to address these challenges. It primarily focuses on three points: 1) how to improve the printability of LM and its wettability with the substrate, 2) how to select the appropriate printing method to improve the printing speed and ensure the resolution of printing structure, and 3) how to provide perfect encapsulation for LM-based FEs with 3D printing. Following a brief introduction, the mainstream printing technologies and recent developments in the 3D printing of LMs are provided, with an emphasis on the selection of printing method, improvement of printability, encapsulation, and conductivity activation. Then, the revolutionary changes attained after 3D printing of LMs are specifically focused upon. Finally, opinions and potential directions for this thriving discipline are explored.     

3D Electrophoresis‐Assisted Lithography (3DEAL): 3D Molecular Printing to Create Functional Patterns and Anisotropic Hydrogels

The ability to easily generate anisotropic hydrogel environments made from functional molecules with microscale resolution is an exciting possibility for the biomaterials community. This study reports a novel 3D electrophoresis‐assisted lithography (3DEAL) platform that combines elements from proteomics, biotechnology, and microfabrication to print well‐defined 3D molecular patterns within hydrogels. The potential of the 3DEAL platform is assessed by patterning immunoglobulin G, fibronectin, and elastin within nine widely used hydrogels and characterizing pattern depth, resolution, and aspect ratio. Furthermore, the technique's versatility is demonstrated by fabricating complex patterns including parallel and perpendicular columns, curved lines, gradients of molecular composition, and patterns of multiple proteins ranging from tens of micrometers to centimeters in size and depth. The functionality of the printed molecules is assessed by culturing NIH‐3T3 cells on a fibronectin‐patterned polyacrylamide‐collagen hydrogel and selectively supporting cell growth. 3DEAL is a simple, accessible, and versatile hydrogel‐patterning platform based on controlled molecular printing that may enable the development of tunable, chemically anisotropic, and hierarchical 3D environments.     

Impact of 2D and 3D display watching on EEG power spectra: A standardized low-resolution tomography (sLORETA) study

We investigated whether watching two-dimensional television (2DTV) or three-dimensional television (3DTV) resulted in differences in the brain’s processing of sensory information. We divided 25 participants into 2DTV (n = 13) and 3DTV (n = 12) groups. Participants watched 2DTV or 3DTV for 1, 2, or 3 h on different days. Before and at the end of each session, electroencephalography (EEG) was recorded for 10 min. The Simulation Sickness Questionnaire (SSQ) and the Visual Analog Scale (VAS) were used to assess general discomfort before and after watching. Each frequency band of the resting EEG was transformed into a standardized low-resolution electromagnetic tomographic (sLORETA) image. In the 2DTV group, 2 h of watching increased theta power in the central cortex and 3 h of watching increased beta power in the occipital cortex. In the 3DTV group, 3 h of watching increased delta power in the parahippocampal gyrus and middle frontal cortex. Theta power was significantly higher in the insular cortex after 3 h of 3DTV than after 3 h of 2DTV. SSQ scores were significantly higher after 1 h of 2DTV than after 1 h of 3DTV. Watching 2DTV vs. 3DTV triggered different time-dependent activity patterns. Watching 3DTV for 3 h increased slow-wave activity in the prefrontal cortex, while watching 2DTV increased fast-wave activity in the occipitoparietal cortex. Up to 2 h of 3DTV watching did not cause major changes in fatigue or EEG activity compared with 2DTV. Our findings promise to be useful in designing safety guidelines for watching 3DTV.     

电子装联三维结构垂直线和面印刷及回流焊工艺研究

在电子装联领域,焊点通常都位于PCB平面。然而,随着散热、信号屏蔽等要求越来越高,器件及通路的分散性要求焊点能够在三维结构上延伸,从而形成了三维结构的焊点。在回流焊时,垂直(Z轴)方向上的焊料必然要受到重力的影响,特别是在要求连续的线、面焊接时,控制焊料的向下流动是保证焊接质量的难点。针对这一问题,从焊膏性能、印刷工艺和回流工艺三个方面进行分析和实验,不仅获得了连续均匀焊点,而且达到了批量印刷、单次回流的工艺要求,同时减少了器件的热冲击次数。     

Macroscopic Supramolecular Assembly to Fabricate 3D Ordered Structures: Towards Potential Tissue Scaffolds with Targeted Modification

3D ordered structures beyond microscale with targeted modification are catching increasing attention due to its application as tissue scaffolds. Especially scaffolds with necessary growth factors at designated locations are meaningful for induced cell differentiation and tissue formation. However, few fabrication methods can address the challenge of introducing bioactive species to the interior targeted places during the preparation process. Herein, for the first time macroscopic supramolecular assembly is applied to obtain such 3D ordered structures and established a proof‐of‐concept idea of complex scaffold with targeted modification. Taking strip‐like polydimethylsilicon building block as a model system, microscaled multilayered structures have been fabricated with parallel aligned building blocks in each layer. The morphology can be adjusted in a flexible way by tuning the number of layer, the space between two adjacent building blocks, and the position and orientation of each PDMS. The as‐prepared 3D structures are demonstrated biocompatible and potential as scaffolds for 3D cell culture. Moreover, bioactive species can be in situ incorporated into designated locations within the 3D structure precisely. In this way, a novel strategy is provided to address the current challenges in fabricating complex 3D tissue scaffolds with localized protein for future induced cell differentiation.     

基于3D混合树和视觉特性的视频可分级编码算法

分析了视频数据的3D小波系数分布特性,提出了一种基于混合3D树型结构和HVS特性的视频可分级编码算法.首先,依据小波低、高频系数的自相关性,确定相应的树型结构来扫描和处理时间维上的低、高频系数,明显减少了用于定位重要系数的同步信息;其次,依据人类视觉系统对各频率子带敏感程度的不同,对各子带系数进行加权,使得重构视频的重要系数得以排在码流前端,从而在很大程度上提高了中低码率下视频的重构质量.对多种标准测试视频的仿真实验验证了本文算法的有效性,与非对称树型结构编码方案和单一时空方向树结构方案相比,该算法解码图像的Y、U和V 3个分量的均峰值信噪比分别高出0.65dB、1.75dB、1.77dB和0.23dB、2.11dB、1.72dB.此外,算法有效抑制了振铃效应,并获得了更好的主观效果.