塑料薄膜柔性版印刷最佳混合加网技术研究

因传统调幅(AM)网点及调频(FM)网点在阶调表现上存在不足而产生了混合加网技术,即亮调区域和暗调区域使用FM网点、中间调使用AM网点.本研究为在柔性版印刷中获取最佳的混合网点组合配对,采用实验研究法,依据柯达Creo的Maxtone混合加网技术设计了11组不同的混合网点(FM-AM-FM)组合,利用柔性版印刷、混合加网技术及计算机直接制版技术在塑料薄膜上印刷导表,并进行测试.然后测量采用11组混合网点的印刷品之间质量特性的差异,经由统计分析得到FM-AM-FM阶调百分比优化组合为10%-75%-15%(0～10%为FM网点、10%～85%为AM网点、85%～100%为FM网点).本研究结果将为柔性版印刷提供一个参考依据,既提升印刷质量又节省成本,并达到最高的顾客满意程度.     

热处理对增材制造生物纯钛力学性能的影响

选区激光熔化(selective laser melting,SLM)能直接根据CAD模型制备形状复杂的个性化医用植入物.本工作旨在研究SLM和后续热处理后生物纯钛(TAl)的显微组织和力学性能.结果 表明,SLM打印后的TAl合金为针片状a'马氏体组织,且沿建造方向保留初始β柱状晶形貌;热处理后发生再结晶组织转变,形...     

静力试验中C/SiC构件集成式热结构的声发射特性及与材料测试的对比静力试验中C/SiC构件集成式热结构的声发射特性及与材料测试的对比

在对C/SiC复合材料常温拉伸试验的损伤表征和声发射演化特性进行简要分析的基础上,针对构件集成式设计带来的复杂性特点,对某C/SiC热结构在常温静力试验中的声发射特性进行了分析。给出了试验中声发射特征参数的分类特点。根据试验加载中声发射信号规律,给出了结构的损伤演化模式。通过与材料级声发射信号的对比,判断了试验加载与热结构极限破坏载荷之间的裕度。由此将声发射测试从材料级别的研究延伸到大型C/SiC热结构。      

Optimization Design of Crystal Thickness Combination for Dual-layer-offset DOI Detector for Brain PET

Dual-layer-offset crystal array is a low cost and simple scheme for positron emission tomography (PET) system to achieve depth of interaction (DOI) information. Different thickness combinations of two layer crystals influence system performances. Monte Carlo simulations using GATE toolkit were implemented to optimize the design by evaluating the performances of the system with different thickness combinations in this study. Eleven magnetic resonance imaging (MRI) compatible brain PET inserted systems with an inner diameter of 345 mm, dual layer LYSO of 20 mm total thickness and inner layer thickness varied from 0 mm to 10 mm with a step size of 1 mm were built. Six point sources in the x-axis of the center slice from x=0 cm to x=10 cm with an interval of 2 cm were simulated. The sensitivity at the center was calculated and the radial resolutions were evaluated using the reconstructed points by the filtered back projection algorithm. The results show that dual-layer crystal design has a slight sensitivity decrease, but can significantly improve the radial spatial resolution and the resolution uniformity compared with the single-layer design. With the thickness increase of the inner crystal, the average radial spatial resolution decreases and then increases, and achieves minimal at inner layer with a thickness of 8 mm. In conclusion, 8 mm in the inner layer and 12 mm in the outer layer is the optimal design for the brain PET system with 20 mm dual-layer-offset crystal proposed in this study.     

不同表面基团的纤维素纳米晶体薄膜在不同磁场下的光学特性响应

本文探究了磁场对不同表面基团的纤维素纳米晶体(Cellulose Nanocrystal,CNC)薄膜光学特性的影响。以硫酸化纤维素纳米晶体(S-CNC)为原料,通过2,2,6,6-四甲基哌啶-1-氧基自由基(TEMPO)氧化制备表面带有羧基的纳米纤维素(T-CNC),并采用傅里叶红外光谱、扫描电子显微镜和Zeta电位对其基本结构进行表征。并在无磁场、垂直磁场、倾斜磁场、水平磁场四种模式下观察磁场对不同表面电荷CNC薄膜的影响。结果表明,T-CNC表面带有羧基,S-CNC表面带有硫酸酯基。由于表面电荷不同,使得T-CNC电位绝对值低于S-CNC。两种CNC由于表面电荷差异表现出不同的自组装模式,其中T-CNC为同心自组装,S-CNC为手性向列自组装,且自组装模式的差异不因磁场而改变。但T-CNC与S-CNC在自组装过程中的排列均受到磁场影响。随着磁场取向的不同,两种薄膜的颜色因CNC的排列发生变化而受到影响,其中垂直磁场对两种CNC薄膜的影响最为显著,能使薄膜中CNC的排列更加均匀紧密,从而提升薄膜颜色的均匀性。不同表面基团CNC的自组装薄膜在不同磁场下的颜色响应研究为后续对CNC虹彩...     

A Differentially Private Data Aggregation Method Based on Worker Partition and Location Obfuscation for Mobile Crowdsensing

With the popularity of sensor-rich mobile devices, mobile crowdsensing (MCS) has emerged as an effective method for data collection and processing. However, MCS platform usually need workers’ precise locations for optimal task execution and collect sensing data from workers, which raises severe concerns of privacy leakage. Trying to preserve workers’ location and sensing data from the untrusted MCS platform, a differentially private data aggregation method based on worker partition and location obfuscation (DP-DAWL method) is proposed in the paper. DP-DAWL method firstly use an improved K-means algorithm to divide workers into groups and assign different privacy budget to the group according to group size (the number of workers). Then each worker’s location is obfuscated and his/her sensing data is perturbed by adding Laplace noise before uploading to the platform. In the stage of data aggregation, DP-DAWL method adopts an improved Kalman filter algorithm to filter out the added noise (including both added noise of sensing data and the system noise in the sensing process). Through using optimal estimation of noisy aggregated sensing data, the platform can finally gain better utility of aggregated data while preserving workers’ privacy. Extensive experiments on the synthetic datasets demonstrate the effectiveness of the proposed method.     

不宁腿综合征临床特点与规范化治疗

不宁腿综合征（restless legs syndrome, RLS）是临床常见的运动感觉性神经系统疾病。主要表现为强烈、迫切想要移动肢体冲动/欲望，常常伴随着肢体深处不舒服或难以描述的感觉，夜间睡眠或安静时出现或加重，具有昼夜节律性，按摩或活动后缓解，安静时加重。本文将从RLS的发病机制、临床表现、诊断标准、鉴别诊断和治疗等方面进行系统综述。     

Stochastic gradient Hamiltonian Monte Carlo with variance reduction for Bayesian inference

Machine Learning - Gradient-based Monte Carlo sampling algorithms, like Langevin dynamics and Hamiltonian Monte Carlo, are important methods for Bayesian inference. In large-scale settings,...     

Oxide-Based Electrolyte-Gated Transistors for Spatiotemporal Information Processing

Spiking neural networks (SNNs) sharing large similarity with biological nervous systems are promising to process spatiotemporal information and can provide highly time- and energy-efficient computational paradigms for the Internet-of-Things and edge computing. Nonvolatile electrolyte-gated transistors (EGTs) provide prominent analog switching performance, the most critical feature of synaptic element, and have been recently demonstrated as a promising synaptic device. However, high performance, large-scale EGT arrays, and EGT application for spatiotemporal information processing in an SNN are yet to be demonstrated. Here, an oxide-based EGT employing amorphous Nb₂O₅ and Li_xSiO₂ is introduced as the channel and electrolyte gate materials, respectively, and integrated into a 32 × 32 EGT array. The engineered EGTs show a quasi-linear update, good endurance (10⁶) and retention, a high switching speed of 100 ns, ultralow readout conductance ( < 100 nS), and ultralow areal switching energy density (20 fJ µ m⁻²). The prominent analog switching performance is leveraged for hardware implementation of an SNN with the capability of spatiotemporal information processing, where spike sequences with different timings are able to be efficiently learned and recognized by the EGT array. Finally, this EGT-based spatiotemporal information processing is deployed to detect moving orientation in a tactile sensing system. These results provide an insight into oxide-based EGT devices for energy-efficient neuromorphic computing to support edge application.     

Analysis of AC Transport Loss in Conductor on Round Core Cables

Journal of Superconductivity and Novel Magnetism - The conductor on round core (CORC) cable wound with second-generation high-temperature superconducting (HTS) tapes is a promising cable candidate...