基于消息代理的OPC UA发布/订阅模式研究与实现

针对目前OPC UA客户端/服务器通信模式中存在的紧耦合、服务器性能瓶颈等问题,进行了OPC UA发布/订阅通信模式总体架构的研究。首先具体分析了UA的核心功能,包括地址空间技术和数据编码技术,并在两者的基础上,利用消息代理机制,完成了发布者和订阅者的功能开发。还通过实验进一步验证了功能的稳定性和对数据的传输能力,结果表明,此模式可以满足大多数工业需求。

基于粒子滤波算法的锂离子电池剩余寿命预测方法研究

运用粒子滤波算法,进行了锂离子电池剩余寿命(RUL)的预测,提出了一种基于模型法和数据驱动法相融合的简单有效的RUL预测方法。该方法通过模型法和数据驱动法的融合,将双指数经验退化模型进行变形,以减少模型参数,降低参数训练难度,利用粒子滤波算法跟踪电池容量衰退的过程;为提高预测精确度,引入自回归(AR)时间序列模型修正状态空间方程的观测值。实验证实,该方法可以有效地预估出锂电池的剩余寿命。

High-throughput discovery of high Curie point two-dimensional ferromagnetic materials

Databases for two-dimensional materials host numerous ferromagnetic materials without the vital information of Curie temperature since its calculation involves a manually intensive complex process.In this work,we develop a fully automated,hardwareaccelerated,dynamic-translation based computer code,which performs first principles-based computations followed by Heisenberg model-based Monte Carlo simulations to estimate the Curie temperature from the crystal structure.We employ this code to conduct a high-throughput scan of 786 materials from a database to discover 26 materials with a Curie point beyond 400 K.For rapid data mining,we further use these results to develop an end-to-end machine learning model with generalized chemical features through an exhaustive search of the model space as well as the hyperparameters.We discover a few more high Curie point materials from different sources using this data-driven model.Such material informatics,which agrees well with recent experiments,is expected to foster practical applications of two-dimensional magnetism.

High-throughput design of functional-engineered MXene transistors with low-resistive contacts

Two-dimensional material-based transistors are being extensively investigated for CMOS(complementary metal oxide semiconductor)technology extension;nevertheless,downscaling appears to be challenging owing to high metal-semiconductor contact resistance.Here,we propose a functional group-engineered monolayer transistor architecture that takes advantage of MXenes’natural material chemistry to offer low-resistive contacts.We design an automated,high-throughput computational pipeline that first performs hybrid density functional theory-based calculations to find 16 sets of complementary transistor configurations by screening more than 23,000 materials from an MXene database and then conducts self-consistent quantum transport calculations to simulate their current-voltage characteristics for channel lengths ranging from 10 nm to 3 nm.Performance of these devices has been found to meet the requirements of the international roadmap for devices and systems(IRDS)for several benchmark metrics(on current,power dissipation,delay,and subthreshold swing).The proposed balanced-mode,functional-engineered MXene transistors may lead to a realistic solution for the sub-decananometer technology scaling by enabling doping-free intrinsically low contact resistance.

RapidET:a MEMS-based platform for label-free and rapid demarcation of tumors from normal breast biopsy tissues

The rapid and label-free diagnosis of malignancies in ex vivo breast biopsy tissues has significant utility in pathology laboratories and operating rooms.We report a MEMS-based platform integrated with microchips that performs phenotyping of breast biopsy tissues using electrothermal sensing.The microchip,fabricated on a silicon substrate,incorporates a platinum microheater,interdigitated electrodes(IDEs),and resistance temperature detectors(RTDs)as on-chip sensing elements.The microchips are integrated onto the platform using a slide-fit contact enabling quick replacement for biological measurements.The bulk resistivity(ρB),surface resistivity(ρS),and thermal conductivity(k)of deparaffinized and formalin-fixed paired tumor and adjacent normal breast biopsy samples from N=8 patients were measured.For formalin-fixed samples,the meanρB for tumors showed a statistically significant fold change of 4.42(P=0.014)when the tissue was heated from 25°C to 37°C compared to the adjacent normal tissue,which showed a fold change of 3.47.The meanρS measurements also showed a similar trend.The mean k of the formalinfixed tumor tissues was 0.309±0.02Wm^(-1)K^(-1)compared to a significantly higher k of 0.563±0.028 Wm^(-1)K^(-1)for the adjacent normal tissues.A similar trend was observed inρB,ρS,and k for the deparaffinized tissue samples.An analysis of a combination ofρ_(B,)ρ_(S,)and k using Fisher’s combined probability test and linear regression suggests the advantage of using all three parameters simultaneously for distinguishing tumors from adjacent normal tissues with higher statistical significance.

Realizing unipolar and bipolar intrinsic skyrmions in MXenes from high-fidelity first-principles calculations

Magnetic skyrmions,which are topologically protected tiny spin textures,have emerged as information carriers in energy-efficient logic and memory devices.Skyrmions are commonly realized by inducing large Dzyaloshinskii–Moriya interaction(DMI)in the interface of heavy metal heterolayers.With the advent of two-dimensional magnetism,it is being envisioned to host intrinsic skyrmions in a monolayer,which will be free from any interfacial defect and stacking order.Here using high-fidelity exchange-correlation functional-based first-principles calculations,we investigate such a possibility in methodically designed non-centrosymmetric MXene structures.From a search space of about 3000 materials,our customized high-throughput computational pipeline systematically harnesses out-of-the-plane and in-plane magnetism along with strong DMI to realize typical‘unipolar’skyrmions in 78 materials and exotic‘bipolar’skyrmions in 13 materials.Micromagnetic and atomistic Monte Carlo simulations further reveal that skyrmions in some of these materials may be stable at room temperature without any external magnetic field.Our study may pave the way for the practical realization of skyrmions-based information technology.

Vertical Cavity Semiconductor Optical Amplifiers:Physics and Applications

A review is presented of the state-of-the-art in vertical cavity semiconductor optical amplifiers (VCSOAs), focusing in particular on recent developments in theoretical analysis, wavelengths of operation, materials systems, potential applications and a design example.

Improved rate-distortion optimized video coding using non-integer bit estimation and multiple Lambda search

Many modern video encoders use the Lagrangian rate-distortion optimization （RDO） algorithm for mode deci- sions during the compression procedure. For each encoding stage, this approach involves minimizing a cost, which is a function of rate, distortion and a multiplier called Lambda. This paper proposes to improve the RDO process by applying two modifications. The first modification is to increase the ac- curacy of rate estimation, which is achieved by computing a non-integer number of bits for arithmetic coding of the syntax elements. This leads to a more accurate cost computation and therefore a better mode decision. The second modification is to search and adjust the value of Lambda based on the char- acteristics of each coding stage. For the encoder used, this paper proposes to search multiple values of Lambda for the intra-4x4 mode decision. Moreover, a simple shift in Lambda value is proposed for motion estimation. Each of these modi- fications offers a certain gain in RDO performance, and, when all are combined, an average bit-rate saving of up to 7.0% can be achieved for the H.264/AVC codec while the same concept is applicable to the H.265/HEVC codec as well. The extra added complexity is contained to a certain level, and is also adjustable according to the processing resources available.