基于中文学术文献的领域本体概念层次关系抽取研究

基于学术文献构建领域本体对促进领域学科发展具有重要的意义。本文提出了一种以中文学术文献为数据源,半自动化抽取领域本体层次关系的框架方法。首先,构建了一个通用的领域本体层次关系的细粒度研究框架。其次,设计了一种新的概念表示方法,融合了深度学习方法得到的概念语义特征和上下文的时间序列词频。进一步结合了AP聚类、Prim算法和Web搜索引擎的查询数据,提出了基于规则推理的本体概念层次关系抽取算法(RROCHE),实现了半自动化概念层次关系抽取。最后,基于中文分词领域的中文学术文献数据,通过数值实验方法讨论了方法的可行性和有效性。本文提出的框架方法也非常容易推广并应用到各领域本体层次关系任务中。

斯格明子电子学的研究进展

在过去的半个世纪中,微电子技术一直沿着著名的摩尔定律快速发展,当前已经达到单芯片可集成上百亿晶体管.然而随着晶体管尺寸的缩小,因量子效应所产生的漏电流及其所导致的热效应使得这一定律遇到瓶颈.自旋电子技术由于引入了电子自旋这一全新的自由度,将有望大幅度降低器件功耗,突破热效应枷锁.斯格明子是一种具有拓扑保护的类粒子自旋结构,有望成为下一代自旋电子信息载体,引起了从物理到电子领域的广泛关注.由于其特殊的拓扑性质,斯格明子具备尺寸小、结构稳定、驱动阈值电流小等诸多优点,室温下斯格明子的成核、输运及探测进一步验证了其广泛的应用潜力,由此诞生了研究相关器件及应用的斯格明子电子学.本综述从电子学角度首先介绍斯格明子的基础概念及发展现状、理论及实验研究方法,重点阐述斯格明子器件的写入、调控及读取功能,介绍了一系列具有代表性的新型信息器件;最后,结合斯格明子电子学现状分析了目前所面临的发展瓶颈以及未来的应用前景.

基于动态规划的知识库问答方法

基于知识库的问答(question answering over knowledge base,QA-KB)致力于从语义角度更准确地分析用户的查询意图,并用简洁准确的结果回答用户的自然语言问题.现有的QA-KB方法大多基于APA(alignment-prediction-answering)框架,将整个问答过程拆解为多个分离的任务,采用贪心思想作为决策本质,缺乏统一化的建模与全局化的优化策略.因此提出一种端到端的无监督QA-KB框架,并使用动态规划算法支撑全局的优化与决策.实验结果表明该方法在中文问答数据集中取得了良好效果,尤其在解决多跳问题上有突出表现,为现有的问答系统提供了新思路.

Influence of Surface Structures on Quality of CdTe(100) Thin Films Grown on GaAs(100) Substrates

We report the epitaxial growth of single-crystalline Cd Te（100） thin films on Ga As（100） substrates using molecular beam epitaxy. By controlling the substrate pre-heated temperature with adjustable Te flux, three different reconstructed surfaces are realized, and their influence on the subsequent Cd Te growth is investigated. More importantly, we find that both the presence of a thin native oxide layer and the formation of Ga-As-Te bonds at the interface enable the growth along the（100） orientation and help to reduce the threading dislocations and other defects. Our results provide new opportunities for compound semiconductor heterogeneous growth via interfacial engineering.

Wireless Acoustic Sensor Networks and Edge Computing for Rapid Acoustic Monitoring

Passive acoustic monitoring is emerging as a promising solution to the urgent, global need for new biodiversity assessment methods. The ecological relevance of the soundscape is increasingly recognised, and the affordability of robust hardware for remote audio recording is stimulating international interest in the potential for acoustic methods for biodiversity monitoring.The scale of the data involved requires automated methods,however, the development of acoustic sensor networks capable of sampling the soundscape across time and space and relaying the data to an accessible storage location remains a significant technical challenge, with power management at its core. Recording and transmitting large quantities of audio data is power intensive,hampering long-term deployment in remote, off-grid locations of key ecological interest. Rather than transmitting heavy audio data, in this paper, we propose a low-cost and energy efficient wireless acoustic sensor network integrated with edge computing structure for remote acoustic monitoring and in situ analysis.Recording and computation of acoustic indices are carried out directly on edge devices built from low noise primo condenser microphones and Teensy microcontrollers, using internal FFT hardware support. Resultant indices are transmitted over a ZigBee-based wireless mesh network to a destination server.Benchmark tests of audio quality, indices computation and power consumption demonstrate acoustic equivalence and significant power savings over current solutions.

Perpendicular magnetization switching by large spin-orbit torques from sputtered Bi2Te3

Spin-orbit torque(SOT)effect is considered as an efficient way to switch the magnetization and can inspire various high-performance spintronic devices.Recently,topological insulators(TIs)have gained extensive attention,as they are demonstrated to maintain a large effective spin Hall angle(θeff SH),even at room temperature.However,molecular beam epitaxy(MBE),as a precise deposition method,is required to guarantee favorable surface states of TIs,which hinders the prospect of TIs towards industrial application.In this paper,we demonstrate that Bi2Te3 films grown by magnetron sputtering can provide a notable SOT effect in the heterostructure with perpendicular magnetic anisotropy CoTb ferrimagnetic alloy.By harmonic Hall measurement,a high SOT efficiency(8.7±0.9 Oe/(10^9 A/m^2))and a largeθ^eff SH(3.3±0.3)are obtained at room temperature.Besides,we also observe an ultra-low critical switching current density(9.7×10^9 A/m^2).Moreover,the low-power characteristic of the sputtered Bi2Te3 film is investigated by drawing a comparison with different sputtered SOT sources.Our work may provide an alternative to leverage chalcogenides as a realistic and efficient SOT source in future spintronic devices.

Enhanced Anomalous Hall Effect of Pt on an Antiferromagnetic Insulator with Fully Compensated Surface

We report a significantly enhanced anomalous Hall effect(AHE)of Pt on antiferromagnetic insulator thin film(3-unit-cell La_(0.7)Sr_(0.3)MnO_(3),abbreviated as LSMO),which is one order of magnitude larger than that of Pt on other ferromagnetic(e.g.Y_(3)Fe_(5)O_(12))and antiferromagnetic(e.g.Cr_(2)O_(3))insulator thin films.Our experiments demonstrate that the antiferromagnetic La_(0.7)Sr_(0.3)MnO_(3)with fully compensated surface suppresses the positive anomalous Hall resistivity induced by the magnetic proximity effect and facilitates the negative anomalous Hall resistivity induced by the spin Hall effect.By changing the substrate’s temperature during Pt deposition,we observed that the diffusion of Mn atoms into Pt layer can further enhance the AHE.The anomalous Hall resistivity increases with increasing temperature and persists even well above the Neel temperature(T_(N))of LSMO.The Monte Carlo simulations manifest that the unusual rise of anomalous Hall resistivity above T_(N)originates from the thermal induced magnetization in the antiferromagnetic insulator.

Progress in research on ultrasound radiomics for predicting the prognosis of breast cancer

Breast cancer is the most common malignant tumor and the leading cause of cancer-related deaths in women worldwide.Effective means of predicting the prognosis of breast cancer are very helpful in guiding treatment and improving patients'survival.Features extracted by radiomics reflect the genetic and molecular characteristics of a tumor and are related to its biological behavior and the patient's prognosis.Thus,radiomics provides a new approach to noninvasive assessment of breast cancer prognosis.Ultrasound is one of the commonest clinical means of examining breast cancer.In recent years,some results of research into ultrasound radiomics for diagnosing breast cancer,predicting lymph node status,treatment response,recurrence and survival times,and other aspects,have been published.In this article,we review the current research status and technical challenges of ultrasound radiomics for predicting breast cancer prognosis.We aim to provide a reference for radiomics researchers,promote the development of ultrasound radiomics,and advance its clinical application.

Mining Typical Treatment Duration Patterns for Rational Drug Use from Electronic Medical Records

Rational drug use requires that patients receive medications for an adequate period of time.The adequate duration time of medications not only improve the therapeutic effect of medicines,but also reduce the side effects and adverse reactions of medicines.This paper proposes a data-driven method to mine typical treatment duration patterns for rational drug use from electronic medical records (EMRs).Firstly,a quintuple is defined to describe drug use duration statistics (DUDS) for each drug and treatment record is further represented with DUDS vector (DUDSV).Next a similarity measure method is adopted to compute the similarity between treatment records.Meanwhile,a clustering algorithm is used to cluster all patient treatment records to extract typical treatment duration patterns including typical drug sets,effective drug use day sets,and the DUDSs of each typical drug.Then the extracted typical treatment duration patterns are evaluated and annotated based on patients' demographic information,disease severity scores,treatment outcome and diagnostic information.Finally,a real-world EMR dataset is performed to indicate that the approach we proposed can effectively mine typical treatment duration patterns from EMRs and recommend the appropriate treatment regimens for patients based on their admission information.

Prototyping federated learning on edge computing systems

1 Introduction Deep learning has obtained a great success in computing technologies and has been afiliated to people's lives insepa-rably recent years.Nowadays,the most common approach to deploy these deep learning models is to collect the users data and train them in central servers.Nevertheless,the users data might be inevitably undermined during the process of col-lection and uploading,and users sensitive information might be exposed to danger.Aiming at reducing the risk of privacy leakage,Google proposed federated learning,which has been successfully applied to several applications,e.g.,data alliance among enterprises[1],next word prediction in Gboard[2],etc.

High temperature performance of coaxial h-BN/CNT wires above 1,000 ℃:Thermionic electron emission and thermally activated conductivity

The development of wires and cables that can tolerate extremely high temperatures will be very important for probing extreme environments, such as in solar exploration, fire disasters, high-temperature materials processing, aeronautics and astronautics. In this paper, a lightweight high-temperature coaxial h-boron nitride (BN)/carbon nanotube (CNT) wire is synthesized by the chemical vapor deposition (CVD) epitaxial growth of h-BN on CNT yarn. The epitaxially grown h-BN acts as both an insulating material and a jacket that protects against oxidation. It has been shown that the thermionic electron emission (1,200 K) and thermally activated conductivity (1,000 K) are two principal mechanisms for insulation failure of h-BN at high temperatures. The thermionic emission of h-BN can provide the work function of h-BN, which ranges from 4.22 to 4.61 eV in the temperature range of 1,306-1,787 K. The change in the resistivity of h-BN with temperature follows the ohmic conduction model of an insulator, and it can provide the “electron activation energy”(the energy from the Fermi level to the conduction band of h-BN), which ranges from 2.79 to 3.08 eV, corresponding to a band gap for h-BN ranging from 5.6 to 6.2 eV. However, since the leakage current is very small, both phenomena have no obvious influence on the signal transmission at the working temperature. This lightweight coaxial h-BN/CNT wire can tolerate 1,200 ℃ in air and can transmit electrical signals as normal. It is hoped that this lightweight high-temperature wire will open up new possibilities for a wide range of applications in extreme high-temperature conditions.

A Simulation Research Towards Better Leverage of Sales Ranking

As a kind of the most significantly popular information in markets,the sales ranking has great impacts on consumer choice.However,there are few discussions on how sales ranking should be provided to consumers in the literature.This paper aims to answer the following two questions:1)To what extent does the sales ranking influence consumer choices;2)When the sales ranking should be provided to consumers.To do so,this paper first constructs a sales ranking model and then provides detailed simulation experiments to demonstrate the model.The experimental results show that for markets where consumer preferences are dramatically different,such as music and movie markets,sales rankings do not have significant influences on consumer choices and should not be provided to consumers until a large number of early independent consumer choices have been accumulated.But for markets in which consumer preferences are similar,such as markets for official supplies,sales rankings have more influences on consumer choices and should be provided to consumers earlier.Furthermore,an evolution strategy is proposed to ascertain the most suitable sales rankings(characterised by suitable influence strength and suitable release time)for some specified online markets.The comparison results show that the optimized sales rankings not only can help consumers discover higher-quality products but also can improve overall sales.

Large spin Hall effect and tunneling magnetoresistance in iridium-based magnetic tunnel junctions

Magnetic tunnel junctions(MTJs)switched by spin-orbit torque(SOT)have attracted substantial interest owing to their advantages of ultrahigh speed and prolonged endurance.Both field-free magnetization switching and high tunneling magnetoresistance(TMR)are critical for the practical application of SOT magnetic random access memory(MRAM).In this work,we propose an MTJ structure based on an iridium(Ir)bottom layer.Ir metal is a desirable candidate for field-free SOT switching owing to its strong intrinsic spin Hall conductivity(SHC),which can be enhanced via doping.Herein,we study TMR in Ir-based MTJs with symmetric and asymmetric structures.Ir-based MTJs exhibit large TMR,which can be further enhanced by heavy metal symmetry owing to the resonant tunneling effect.Our comprehensive investigations illustrate that Ir-based MTJs are promising candidates for realizing SOT switching and high TMR.

Multi-layer magnetic recording driven by a tunable laser

All-optical magnetization switching with features of low-power consumption and high writing speed is a promising road map to satisfy the demand for volume data storage. To promote denser and faster magnetic recording technologies, herein, all-optical helicity-dependent switching(AO-HDS) in multi-layer magnetic recording is proposed based on the chromatic aberration of an optical lens(Thorlabs’ s N-BK7 plano-convex uncoated lens).The power of the incident beams and the thickness of the multi-layer magnetic recording film are designed carefully. Besides, the uniformity of this multi-layer magnetic recording is optimized. At last, a prototype system of information multiplexing based on this multi-layer magnetic recording technology is constructed as well. Flexible and controllable magnetization reversals in different layers are also demonstrated by tuning the wavelength and helicity of working beams. We believe that such a prototype system can pave the way for increasing the storage density in an effective and low-cost mode.

The second discriminant of a univariate polynomial

We define the second discriminant D_(2)of a univariate polynomial f of degree greater than 2 as the product of the linear forms 2r_(k)-r_(i)-r_(j)for all triples of roots r_(i),r_(k),r_(j)of f with i<j and j≠k,k≠i.D_(2)vanishes if and only if f has at least one root which is equal to the average of two other roots.We show that D_(2)can be expressed as the resultant of f and a determinant formed with the derivatives of f,establishing a new relation between the roots and the coefficients of f.We prove several notable properties and present an application of D_(2).

Non-salient region erasure for time series augmentation

1 Introduction Time seriesaugmentationis an essential approachto solvethe overfitting problem on the time series classification(TSC)task[1,2].Although existing approaches perform better in mitigating this problem,none of them focus on protecting saliency regions on time series.The key informative shapelets contained in these regions are the core basis for distinguishing categories(e.g.,upward spikes in ECG and high amplitude in Sensor).

Visualizing nonlinear resonance in nanomechanical systems via single-electron tunneling

Numerous reports have elucidated the importance of mechanical resonators comprising quantum-dot-embedded carbon nanotubes(CNTs)for studying the effects of single-electron transport.However,there is a need to investigate the single-electron transport that drives a large amplitude into a nonlinear regime.Herein,a CNT hybrid device has been investigated,which comprises a gate-defined quantum dot that is embedded into a mechanical resonator under strong actuation conditions.The Coulomb peak positions synchronously oscillate with the mechanical vibrations,enabling a single-electron Chopper*1 mode.Conversely,the vibration amplitude of the CNT versus its frequency can be directly visualized via detecting the time-averaged single-electron tunneling current.To understand this phenomenon,a general formula is derived for this time-averaged single-electron tunneling current,which agrees well with the experimental results.By using this visualization method,a variety of nonlinear motions of a CNT mechanical oscillator have been directly recorded,such as Duffing nonlinearity,parametric resonance,and double-,fractional-,mixed-frequency excitations.This approach opens up burgeoning opportunities for investigating and understanding the nonlinear motion of a nanomechanical system and its interactions with electron transport in quantum regimes.