Development and Evaluation of Intersection-Based Turning Movement Counts Framework Using Two Channel LiDAR Sensors

This paper presents vehicle localization and tracking methodology to utilize two-channel LiDAR data for turning movement counts. The proposed methodology uniquely integrates a K-means clustering technique, an inverse sensor model, and a Kalman filter to obtain the final trajectories of an individual vehicle. The objective of applying K-means clustering is to robustly differentiate LiDAR data generated by pedestrians and multiple vehicles to identify their presence in the LiDAR’s field of view (FOV). To localize the detected vehicle, an inverse sensor model was used to calculate the accurate location of the vehicles in the LiDAR’s FOV with a known LiDAR position. A constant velocity model based Kalman filter is defined to utilize the localized vehicle information to construct its trajectory by combining LiDAR data from the consecutive scanning cycles. To test the accuracy of the proposed methodology, the turning movement data was collected from busy intersections located in Newark, NJ. The results show that the proposed method can effectively develop the trajectories of the turning vehicles at the intersections and has an average accuracy of 83.8%. Obtained R-squared value for localizing the vehicles ranges from 0.87 to 0.89. To measure the accuracy of the proposed method, it is compared with previously developed methods that focused on the application of multiple-channel LiDARs. The comparison shows that the proposed methodology utilizes two-channel LiDAR data effectively which has a low resolution of data cluster and can achieve acceptable accuracy compared to multiple-channel LiDARs and therefore can be used as a cost-effective measure for large-scale data collection of smart cities.

Study of ultra-wideband radar signals-generated technology using two-channel signal generator

Synthesis of ultra-wideband （UWB） linear frequency modulation radar signals is a very important technology for microwave imaging, target identification and detection of low radar-cross-section （RCS） targets. A new method of UWB radar signals generation with two-channel signal generator is presented. The realization structure is given; the principle and errors of signal synthesis are analyzed. At the same time, an automatic .adjustment measure of signal phase is proposed because of phase discontinuity of waveform in this method. The simulation experiment and analysis results indicate that radar signals with large instantaneous bandwidth can be generated by means of this method on the condition that the high-speed digital devices are limited.

Comparative numerical study of single and two-phase models of nanofluid heat transfer in wavy channel

The main purpose of this study is to survey numerically comparison of two- phase and single phase of heat transfer and flow field of copper-water nanofluid in a wavy channel. The computational fluid dynamics （CFD） prediction is used for heat transfer and flow prediction of the single phase and three different two-phase models （mixture, volume of fluid （VOF）, and Eulerian）. The heat transfer coefficient, temperature, and velocity distributions are investigated. The results show that the differences between the temperature fie].d in the single phase and two-phase models are greater than those in the hydrodynamic tleld. Also, it is found that the heat transfer coefficient predicted by the single phase model is enhanced by increasing the volume fraction of nanoparticles for all Reynolds numbers; while for the two-phase models, when the Reynolds number is low, increasing the volume fraction of nanoparticles will enhance the heat transfer coefficient in the front and the middle of the wavy channel, but gradually decrease along the wavy channel.

Tunable RF excited waveguide CO-2 laser with two unequal long channels

Presents a waveguide CO 2 laser with two unequal long channels excited by radio frequency (RF) which has more than 30 laser lines from a long channel of 400 mm with grating, and 3 laser lines from a short channel of 200 mm by PZT.

Numerical simulation of the gas-solid two-phase flow inside the multi-channel nozzle for the surface nanocrystallization induced by the ultrasonic particulate peening

Using a gas-solid two-phase model(a discrete phase model),the authors investigated the flow field inside the multi-channel nozzle for surface nanocrystallization(SNC)induced by the ultrasonic particulate peening(USPP).By computation,the velocity fields of both the gas and the solid phases were simulated and the track of the solid phase was analyzed in detail.It can be found that the velocities of the two phases are able to reach an ultrasonic level;meanwhile,the dispersion width of the solid phase at the nozzle exit is less than that of the gas phase.When particle diameters are less than 5 μm,there is a decreasing trend in the dispersion width of the solid phase with an increase in particle diameters.The trend becomes stable as the particle diameters are greater than 5 μm;in the meantime,the distribution of solid particles is near the axis of the jet flow.The optimal standoff distance between the nozzle and the substrate in the process of USPP is about 120 mm.Simulation results can help improve the design of mass-production-oriented multi-channel nozzles for SNC induced by USPP.

Entropy squeezing of a moving atom and control of noise of the quantum mechanical channel via the two-photon process

Based on the quantum information theory, we have investigated the entropy squeezing of a moving two-level atom interacting with the coherent field via the quantum mechanical channel of the two-photon process. The results are compared with those of atomic squeezing based on the Heisenberg uncertainty relation. The influences of the atomic motion and field-mode structure parameter on the atomic entropy squeezing and on the control of noise of the quantum mechanical channel via the two-photon process are examined. Our results show that the squeezed period, duration of optimal entropy squeezing of a two-level atom and the noise of the quantum mechanical channel can be controlled by appropriately choosing the atomic motion and the field-mode structure parameter, respectively. The quantum mechanical channel of two-photon process is an ideal channel for quantum information （atomic quantum state） transmission. Quantum information entropy is a remarkably accurate measure of the atomic squeezing.

Dissipation of a two-mode squeezed vacuum state in the single-mode amplitude damping channel

We explore how a two-mode squeezed vacuum state sechθeab tanh θ[00） evolves when it undergoes a single- mode amplitude dissipative channel with rate of decay k. We find that in this process not only the squeezing parameter decreases, tanhθ → e-kt tanh θ, but also the second-mode vacuum state evolves into a chaotic state exp{bbln[（1 - e-2kt） tanh2 θ]}. The outcome state is no more a pure state, but an entangled mixed state.

Optimal cooperative beamforming design schemes for AF MOMO two-way relay channels

In this paper,beamforming parameters in multiple input multiple output(MIMO) two-way relay channels(TWRCs) are designed.We investigate three communicating scenarios,in which,the source nodes are all equipped with multiple antennas.In the first scenario,one pair of source nodes are communicating with each other under the help of a single multi-antenna equipped relay.A centralized scheme is correspondingly developed where the optimal relay beamforming(RaB) is jointly designed with the transmit beamformings(TBs) and the receive beamformings(RcBs) at both source nodes to minimize the sum of mean square errors(SMSE).In the second scenario,one pair of users in the first scenario is extended to multi-pair of source nodes.We derive a general expression of the optimal RaB matrix of this scenario in the second scheme,and based on which,a RaB matrix is designed to cancel the inter-pair interference(IPI) and to minimize the intra-pair SMSE.At last,we consider a distributed scenario where multiple single-antenna equipped relays are helping the communication between one pair of source nodes.In the scheme associated with this scenario,beamformings are developed under relay total power constraint and relay individual power constraint,respectively.The simulation results reveal that beamformings at source and relay nodes significantly improve the performance in the sense of average bit error rate(BER).The proposed multi-pair scheme has made superior progress in BER performance because it not only can cancel the IPIs but also can balance the useful signal and the noise at each user.Moreover,in one-pair scenarios,the performance of the centralized scheme is better than the distributed one,but the latter is nevertheless much more practical.

Quantum speed-up capacity in different types of quantum channels for two-qubit open systems

A potential acceleration of a quantum open system is of fundamental interest in quantum computation, quantum communication, and quantum metrology. In this paper, we investigate the ＂quantum speed-up capacity＂ which reveals the potential ability of a quantum system to be accelerated. We explore the evolutions of the speed-up capacity in different quantum channels for two-qubit states. We find that although the dynamics of the capacity is varying in different kinds of channels, it is positive in most situations which are considered in the context except one case in the amplitude-damping channel. We give the reasons for the different features of the dynamics. Anyway, the speed-up capacity can be improved by the memory effect. We find two ways which may be used to control the capacity in an experiment： selecting an appropriate coefficient of an initial state or changing the memory degree of environments.

基于双分支注意力U-Net的语音增强方法

针对语音增强网络对全局语音相关特征提取困难、对语音局部上下文信息的捕捉效果不佳的问题,提出了一种基于双分支注意力U-Net的时域语音增强方法,该方法使用U-Net编码器-解码器结构,将单通道带噪语音经过一维卷积后得到的高维时域特征作为输入。首先利用残差连接设计了基于Conformer的残差卷积来增强网络降噪的能力。其次设计了双分支注意力机制结构,利用全局和局部注意力获取带噪语音中更丰富的上下文信息,同时有效表示长序列特征,提取更多样的特征信息。最后结合时域频域损失函数构建了加权损失函数对网络进行训练,提高网络的语音增强性能。使用了多个指标对增强语音的质量和可懂度等进行评价,在公开数据集Voice Bank+DEMAND上的增强后的语音感知质量(PESQ)为3.11,短时可懂度(STOI)为95%,信号失真度(CSIG)为4.44,噪声失真测(CBAK)为3.60,综合质量测度(COVL)为3.81,其中PESQ相较于SE-Conformer提高了7.6%,相较于TSTNN提高了5.1%。实验结果表明,所提方法在语音降噪的各个指标都表现出更优的实验结果,能够完成语音增强任务的相关要求。

基于GRU-DRSN的双通道人体活动识别

人体活动识别(human activity recognizition, HAR)在医疗、军工、智能家居等领域有很大的应用空间。传统机器学习方法特征提取难度较大且精度不高。针对上述问题并结合传感器时序特性,提出了一种融合CBAM(convolutional block attention module)注意力机制的GRU-DRSN双通道并行模型,有效避免了传统串行模型因网络深度加深引起梯度爆炸和消失问题。同时并行结构使得两条支路具有相同的优先级,使用深度残差收缩网络(deep residual shrinkage network, DRSN)提取数据的深层空间特征,同时使用门控循环结构(gated recurrent unit, GRU)学习活动样本在时间序列上的特征,同时进行提取样本不同维度的特征,并通过CBAM模块进行特征的权重分配,最后通过Softmax层进行识别,实现了端对端的人体活动识别。使用公开数据集(wireless sensor data mining, WISDM)进行验证,模型平均精度达到了97.6%,与传统机器学习模型和前人所提神经网络模型相比,有更好的识别效果。

双IRS辅助大规模MIMO系统中基于双时间尺度的信道估计方案

在双智能反射面(IRS)辅助的大规模多入多出(MIMO)通信系统中,为获取信道状态信息(CSI)而进行的信道估计需要较大的导频开销。考虑到基站(BS)-IRS信道与IRS-IRS信道具有高维且准静态的特性,而IRS-用户(UE)信道具有低维且时变的特性,本文提出一种基于双时间尺度的信道估计方案。首先,对于准静态信道,由BS发送导频并基于坐标下降算法和最小二乘法分别估计BS-IRS信道和IRS-IRS信道。然后根据准静态信道的估计结果进一步基于最小二乘法估计IRS-UE信道。仿真结果表明,本文所提出的方案可以采用低于对比方案50%的导频开销来获取低于对比方案近10 dB的估计归一化均方误差(NMSE),实现用更少的导频开销获取更高的信道估计精度。

基于知识蒸馏改进双路BERT的经济类文本情感分析

在互联网时代,越来越多的财务公司选择在财经新闻平台上发表自己的见解,这些评论文本作为舆情的载体,可以充分反映财务公司的情绪,影响公众的投资决策和市场走势.情感分析为分析海量的经济类文本情感类型提供了有效的研究手段.但是,由于特定领域文本的专业性和大标签数据集的不适用性,经济类文本情感分析给传统的情感分析模型带来了巨大的挑战.当将一般情感分析模型应用于经济等特定领域时,模型在准确率与召回率上表现较差.为了克服这些挑战,文章针对财经新闻平台上的经济类文本的情感分析任务,从词表示模型出发,提出了基于知识蒸馏方法的双路BERT(Two-way BERT based on knowledge distillation method)情感分析模型,与文本卷积神经网络(Text-CNN)、卷积递归神经网络(CRNN)、双向长时和短时记忆网络(Bi-LSTM)等算法进行对比实验,结果得出该改进方法相较于其他算法在准确率、召回率和F1值均提升了1%~3%,具有较好的泛化性能.

可级联组网的无线时间比对系统设计

随着科技的发展,越来越多的场合需要实现多个终端间的纳秒量级高精度时间比对,例如现代化军事靶场、战场、雷达观测基地等。现阶段常用的纳秒量级多终端间的时间比对方法是导航卫星共视法,该方法需要搭建数据交换链路,应用的灵活性受限。本文基于无线伪随机码测距原理、双向时间比对原理和码分多址技术,设计出一套可以自适应组网的高精度时间比对系统,不需要额外搭建数据交互通路即可实现级联节点之间的纳秒量级时间比对。其次,分析了利用该系统实现纳秒量级时间比对的技术难点,并提出了相应的解决方法。最后,搭建实验平台对设计的时间比对系统进行验证。实验结果表明,在500 m的无线比对基线下,可以实现优于0.5 ns的静态时间比对精度。

UBE-LIF与后路病灶清除植骨融合内固定术治疗腰椎布氏杆菌性脊柱炎的临床疗效比较

目的对比UBE-LIF(unilateral biportal endoscopic technique with transforaminal lumbar interbody fusion)技术行病灶清除联合经皮椎弓根螺钉内固定术与经典后路病灶清除植骨融合内固定术治疗腰椎布氏杆菌性脊柱炎(LBS)的安全性及临床疗效。方法回顾性分析甘肃省中医院脊柱骨科2020年1月至2022年1月收治的32例LBS患者的临床资料,按术式分为UBE-LIF组(n=15)和开放组(n=17)。记录并分析两组的一般资料、手术相关指标及术后病理HE染色;根据术前、术后1周及术后1、3、6个月和1年的红细胞沉降率(ESR)和C反应蛋白(CRP)变化,腰痛疼痛视觉模拟评分(VAS)、日本骨科协会评分(JOA)、Oswestry功能障碍指数(ODI)评估患者临床恢复情况;影像学方法测量术前及末次随访时腰椎前凸角(LL)和椎间隙高度(DH),并采用Suk分级标准评估椎间植骨融合情况。结果两组患者均顺利完成手术,且均未发生严重术后并发症。两组患者的性别、年龄、手术节段、手术时间、术前ESR和CRP水平、术前VAS、JOA评分及ODI指数、术前LL和DH等资料比较差异均无统计学意义(P>0.05);UBE-LIF组术中出血量、术后引流量、术后下床时间、术后住院时间明显少于开放组(P<0.001);术中取病变组织行病理学检查,均符合布氏杆菌病改变。两组患者均获随访,随访时间12~18个月,平均14.8个月。两组患者的术后各时间点VAS、JOA评分和ODI指数均较术前明显改善(P<0.05);其中两组在术后1周差异较为明显:UBE-LIF组VAS评分低于开放组(P<0.01),两组CRP均较术前升高且UBE-LIF组升高水平明显低于开放组(P<0.001),两组ESR较术前无明显差异(P>0.05);术后其余各时间点两组间VAS、JOA评分和ODI指数、CRP及ESR比较差异无统计学意义(P>0.05)。末次随访时影像学检查示,UBE-LIF组椎间植骨总体融合率为93.3%,开放组为94.1%,差异无统计学意义(χ^(2)=0.246,P=0.884);两组LL和DH均较术前显著改善(P<0.01),两组手术前后差值比较差异无统计学意义(P>0.05)。结论两种术式治疗LBS均安全有效;与后路病灶清除植骨融合内固定术相比,UBE-LIF技术联合经皮椎弓根螺钉内固定术具有术中视野清晰、出血量少、术后早期恢复更快、术后住院时间更短等优势,是一种可行的微创治疗LBS的手术方式。

通道压裂支撑剂缝内分布规律研究

通道压裂是低渗透致密油气藏高效、低成本开发的关键技术,通过采用非连续簇团铺砂的方式,使裂缝中形成具有高导流能力的通道,但目前关于通道压裂的理论研究仍然处于起步阶段.因此,基于计算流体力学建立欧拉-欧拉固液两相流模型,对通道压裂过程中支撑剂的分布状态进行模拟,通过与实验结果进行对比,证明了所建立模型的有效性,并系统研究了不同中顶压裂液(纯压裂液脉冲段)黏度、支撑剂密度、泵注排量对通道压裂通道率的影响.结果表明,中顶压裂液的黏度从1 mPa·s增加到20 mPa·s,通道内平均通道率增加5%;支撑剂密度从1400 kg/m^(3)增加到2000 kg/m^(3)时,缝内通道率减小了7%;排量由3 m^(3)/min增加到7 m^(3)/min时,通道率由28%增加到33.5%后减小到31%.现场应用过程中应使用较高黏度中顶压裂液、较低密度支撑剂和合理的泵注排量以保证裂缝中形成有效支撑通道.

基于共享通道的双向无线电能和信息同时传输系统特性研究

随着电力电子技术、控制技术及开关电源相关技术的发展,电能和信号传输逐渐从以电缆为传输媒介的传统传输方式逐渐向无线传输方向发展。对于需要在水介质中长时间工作的电气设备而言,能量供应是维持其正常工作的关键因素,但由于电缆进行物理连接的传统传输方式在水介质中运用较为不便,并且存在较大的安全隐患,因此需要构建一个基于共享通道的双向无线电能和信息同时传输的系统。

基于双通道回声状态网络的时间序列补全及单步预测

随着物联网的发展,众多传感器采集到大量具有丰富数据相关性的时间序列,为各种数据挖掘应用提供强大的数据支持。然而,一些客观或主观原因(如设备故障、稀疏感知等)往往会造成采集到的数据出现不同程度的缺失。虽然已有很多方法被提出用于解决这一问题,但这些方法在数据相关性方面或考虑不够全面,或计算成本过高。而且,现有方法仅关注对缺失值的补全,未能兼顾下游应用。针对上述不足,设计了一种兼顾补全与预测任务的双通道回声状态网络。两个通道的网络虽共用输入层,但具有各自的储备池和输出层。两者最大的区别是左/右通道的输出层分别表示输入层前/后一个时刻对应的目标值或预补值。最后将两个通道的估计值进行融合,充分利用来自缺失时刻之前和之后的数据相关性以进一步提升性能。两种缺失现象下(随机缺失和分段缺失)不同缺失率的实验结果表明,所提模型无论是在补全精度还是预测精度上都优于目前流行的各类方法。

基于多尺度混合注意力卷积神经网络的关系抽取模型

针对基于卷积神经网络(CNN)的关系抽取获取句子语义信息时缺少不同尺度语义特征信息的获取以及对关键信息的关注的问题,提出基于多尺度混合注意力CNN的关系抽取模型。首先,将关系抽取建模为二维化表示的标签预测;其次,通过多尺度的特征信息提取与融合,获得更细粒度的多尺度空间信息;然后,通过注意力与卷积的结合自适应地细化特征图,使模型关注重要的上下文信息;最后,使用两个预测器共同预测实体对之间的关系标签。实验结果表明,多尺度混合卷积注意力模型能够获取多尺度语义特征信息,而通道注意力和空间注意力通过权重捕捉通道和空间的关键信息,以此来提升关系抽取的性能。所提模型在数据集SemEval(SemEval-2010 task 8)、TACRED(TAC Relation Extraction Dataset)、Re-TACRED(Revised-TACRED)和SciERC(Entities,Relations,and Coreference for Scientific knowledge graph construction)上的F1值分别达到90.32%、70.74%、85.71%和89.66%。

汉防己甲素抗病毒及抗炎作用研究进展

研究国内相关文献,概述汉防己甲素在抑制严重急性呼吸系统综合征冠状病毒Ⅱ型、猪流行性腹泻病毒、登革热病毒等方面的作用,以及其在风湿免疫系统、呼吸系统、神经系统、消化系统等疾病中的抗炎作用等。总结发现,汉防己甲素可以作为双孔通道拮抗剂抑制病毒进入和抑制病毒复制发挥抗病毒作用,还可以通过调控核转录因子蛋白家族(NF-κB)、Janus激酶信号转导和转录激活因子(JAK-STAT)、环氧化酶-2/前列腺素E2(COX-2/PGE2)、Nod样受体蛋白3(NLRP3)等相关信号通路调控炎症因子产生,调节机体抗病毒免疫,从而发挥抗炎和抗病毒的作用。重点分析了汉防己甲素对冠状病毒、埃博拉病毒等多种病毒的干预作用及机制,以及其发挥抗炎作用所涉及到的机制,旨在为今后对汉防己甲素进行深入的药用研究与应用提供参考。参考文献70篇。