共享学习模式下知识服务云平台的构建研究

通过剖析知识服务的内涵和特征,梳理知识服务中存在的问题,结合云计算的特性,给出共享学习模式下知识服务的新模式。构建了知识服务云平台体系结构,设计了知识资源层、知识融合层、知识服务层、运营服务与计费保障体系、客户应用层5个知识服务功能模块,实现了知识资源的共享和协同。     

An end-to-end denoising autoencoder-based deep neural network approach for fault diagnosis of analog circuit

Analog Integrated Circuits and Signal Processing - Fault diagnosis of analog circuit is critical to improve safety and reliability in electrical systems and reduce losses. Traditional fault...     

Low-thermal-budget Au-free ohmic contact to an ultrathin barrier AlGaN/GaN heterostructure utilizing a micro-patterned ohmic recess

A pre-ohmic micro-patterned recess process,is utilized to fabricate Ti/Al/Ti/TiN ohmic contact to an ultrathin-barrier(UTB) AlGaN/GaN heterostructure,featuring a significantly reduced ohmic contact resistivity of 0.56 Ω.mm at an alloy temperat-ure of 550 ℃.The sheet resistances increase with the temperature following a power law with the index of +2.58,while the spe-cific contact resistivity decreases with the temperature.The contact mechanism can be well described by thermionic field emis-sion (TFE).The extracted Schottky barrier height and electron concentration are 0.31 eV and 5.52 × 1018 cm-3,which suggests an intimate contact between ohmic metal and the UTB-AlGaN as well as GaN buffer.A good correlation between ohmic trans-fer length and the micro-pattern size is revealed,though in-depth investigation is needed.A preliminary CMOS-process-compat-ible metal-insulator-semiconductor high-mobility transistor (MIS-HEMT) was fabricated with the proposed Au-free ohmic con-tact technique.     

Amorphous Dual-Layer Coating: Enabling High Li-Ion Conductivity of Non-Sintered Garnet-Type Solid Electrolyte

Garnet-type oxide Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) has attracted considerable attention as a highly promising solid state electrolyte. However, its high ionic conductivity is achievable only after high temperature sintering (≈1200 °C) to form dense pellets but with detrimental brittleness and poor contact with electrodes. Herein, a novel strategy to achieve high Li⁺ ion conductivity of LLZTO without sintering is demonstrated. This is realized by ball milling LLZTO together with LiBH₄, which results in a LLZTO composite with unique amorphous dual coating: LiBO₂ as the inner layer and LiBH₄ as the outer layer. After cold pressing the LLZTO composite powders under 300 MPa to form electrolyte pellets, a high Li⁺ ion conductivity of 8.02 × 10^–5 S cm^–1 is obtained at 30 °C, which is four orders of magnitude higher than that of the non-sintered pristine LLZTO pellets (4.17 × 10^–9 S cm^–1). The composite electrolyte displays an ultrahigh Li⁺ transference number of 0.9999 and enables symmetric Li–Li cells to be cycled for 1000 h at 60 °C and 300 h at 30 °C. The significant improvements are attributed to the continuous ionic conductive network among LLZTO particles facilitated by LiBH₄ that is chemically compatible and electrochemically stable with Li metal electrode.     

Conductive Hydrogel-Based Electrodes and Electrolytes for Stretchable and Self-Healable Supercapacitors

Stretchable self-healing supercapacitors (SCs) can operate under extreme deformation and restore their initial properties after damage with considerably improved durability and reliability, expanding their opportunities in numerous applications, including smart wearable electronics, bioinspired devices, human–machine interactions, etc. It is challenging, however, to achieve mechanical stretchability and self-healability in energy storage technologies, wherein the key issue lies in the exploitation of ideal electrode and electrolyte materials with exceptional mechanical stretchability and self-healing ability besides conductivity. Conductive hydrogels (CHs) possess unique hierarchical porous structure, high electrical/ionic conductivity, broadly tunable physical and chemical properties through molecular design and structure regulation, holding tremendous promise for stretchable self-healing SCs. Hence, this review is innovatively constructed with a focus on stretchable and self-healing CH based electrodes and electrolytes for SCs. First, the common synthetic approaches of CHs are introduced; then the stretching and self-healing strategies involved in CHs are systematically elaborated; followed by an explanation of the conductive mechanism of CHs; then focusing on CH-based electrodes and electrolytes for stretchable self-healing SCs; subsequently, application of stretchable and self-healing SCs in wearable electronics are discussed; finally, a conclusion is drawn along with views on the challenges and future research directions regarding the field of CHs for SCs.     

Ultrasonic Cavitation-Assisted and Acid-Activated Transcytosis of Liposomes for Universal Active Tumor Penetration

Active tumor penetration has been recently recognized as a promising strategy to resolve the limitation of nanomedicine in terms of tumor penetration, but it is challenging to develop active transporting nanocarriers. Here, an ultrasonic cavitation-assisted and acid-activatable active transporting liposome for a broad range of tumors is reported. The active transporting liposome (size and charge dual-conversional gemcitabine prodrug-integrated liposomal nanodroplet (SCGLN)) overcomes the tight blood vessel walls with the aid of ultrasonic cavitation. The SCGLN subsequently transforms from micro-size to nano-size under prolonged ultrasound radiation. Once in the acidic tumor microenvironment, the nanosized SCGLN undergoes negative-to-positive charge-reversal and triggers the cationization-initiated transcytosis to penetrate deep into tumor parenchyma. The gemcitabine-loaded SCGLN exhibits potent antitumor activity in multiple poorly permeable tumor models, which completely erases subcutaneous U251 glioma and stops the progression of orthotopic BxPC3 pancreatic ductal adenocarcinoma. This study presents a promising and universal strategy to develop active penetrating nanomedicines for efficient drug delivery in the low permeable tumor.     

Wood-Inspired Binder Enabled Vertical 3D Printing of g-C3N4/CNT Arrays for Highly Efficient Photoelectrochemical Hydrogen Evolution

2D nanomaterials are very attractive for photoelectrochemical applications due to their ultra-thin structure, excellent physicochemical properties of large surface-area-to-volume ratios, and the resulting abundant active sites and high charge transport capacity. However, the application of commonly used 2D nanomaterials with disordered-stacking is always limited by high photoelectrode tortuosity, few surface-active sites, and low mass transfer efficiency. Herein, inspired by wood structures, a vertical 3D printing strategy is developed to rapidly build vertically aligned and hierarchically porous graphitic carbon nitride/carbon nanotube (g-C₃N₄/CNT) arrays by using lignin as a binder for efficient photoelectrochemical hydrogen evolution. Arising from the directional electron transport and multiple light scattering in the out-of-plane aligned and porous architecture, the resulting g-C₃N₄/CNT arrays display an outstanding hydrogen evolution performance, with the hydrogen yield up to 4.36 µmol (cm⁻² h⁻¹) at a bias of −0.5 V versus RHE, 12.7 and 41.6 times higher than traditional thick g-C₃N₄/CNT and g-C₃N₄ films, respectively. Moreover, this 3D printed structure can overcome the agglomeration problem of the commonly used g-C₃N₄ with powder configuration and shows desirable recyclability and stability. This facile and scalable vertical 3D printing strategy will open a new avenue to highly enhance the photoelectrochemical performance of 2D nanomaterials for sustainably production of clean energy.     

悬浮粒子浓度测定的实验室间比对试验分析

通过对检测实验室间悬浮粒子浓度的比对试验进行分析,以准确了解参加比对的人员和仪器的工作状况,验证相关实验室悬浮粒子浓度的检测能力,确保空气洁净度检测结果的质量.     

Joint face and head tracking inside multi-camera smart rooms

The paper introduces a novel detection and tracking system that provides both frame-view and world-coordinate human location information, based on video from multiple synchronized and calibrated cameras with overlapping fields of view. The system is developed and evaluated for the specific scenario of a seminar lecturer presenting in front of an audience inside a “smart room”, its aim being to track the lecturer’s head centroid in the three-dimensional (3D) space and also yield two-dimensional (2D) face information in the available camera views. The proposed approach is primarily based on a statistical appearance model of human faces by means of well-known AdaBoost-like face detectors, extended to address the head pose variation observed in the smart room scenario of interest. The appearance module is complemented by two novel components and assisted by a simple tracking drift detection mechanism. The first component of interest is the initialization module, which employs a spatio-temporal dynamic programming approach with appropriate penalty functions to obtain optimal 3D location hypotheses. The second is an adaptive subspace learning based 2D tracking scheme with a novel forgetting mechanism, introduced to reduce tracking drift and increase robustness. System performance is benchmarked on an extensive database of realistic human interaction in the lecture smart room scenario, collected as part of the European integrated project “CHIL”. The system consistently achieves excellent tracking precision, with a 3D mean tracking error of less than 16 cm, and is demonstrated to outperform four alternative tracking schemes. Furthermore, the proposed system performs relatively well in detecting frontal and near-frontal faces in the available frame views. This work was performed while Zhenqiu Zhang was on a summer internship with the Human Language Technology Department at the IBM T.J. Watson Research Center.     

Fast Firmware Implementation of RSA-Like Security Protocol for Mobile Devices

In modern mobile communications, personal privacy and security are of top concern to mobile phone subscribers. Yet, owing to the limit of their processing capability, mainstream mobile manufacturers are still unable to apply advanced security protocol to mobile devices. It should be noted that many security protocols are based on RSA algorithm. To implement RSA algorithm and thus apply many advanced security protocols to mobile networks, this paper proposes an efficient and practical method based on the Texas Instruments TMS320C55x family. When the proposed method is employed, it takes only 7.9 milliseconds to perform a 1024-bit RSA encryption operation at the clock frequency of 200 MHz. Our decryption operation is at least 3.5 times faster than the time taken to perform the same operation without employing the proposed method. In addition, the proposed method can stop any power-analysis attack on RSA-based security protocols, thereby enhancing the security of mobile environments.