Restarted FOM Augmented with Ritz Vectors for Shifted Linear Systems

The restarted FOM method presented by Simoncini[7]according to the natural collinearity of all residuals is an efficient method for solving shifted systems,which generates the same Krylov subspace when the shifts are handled simultaneously.However,restarting slows down the convergence.We present a practical method for solving the shifted systems by adding some Ritz vectors into the Krylov subspace to form an augmented Krylov subspace. Numerical experiments illustrate that the augmented FOM approach(restarted version)can converge more quickly than the restarted FOM method.

Complex knee injuries treated in acute phase: Long-term results using Ligament Augmentation and Reconstruction System artificial ligament

AIM To present the long-term results of complex knee injuries, treated early using the Ligament Augmentation and Reconstruction System(LARS) artificial ligament to reconstruct posterior cruciate ligament(PCL).METHODS From September 1997 to June 2010, thirty-eight complex knee injuries were treated, where early arthroscopic PCL reconstructions were undergone, using the LARS(Surgical Implants and Devices, Arc-sur-Tille, France) artificial ligament. Exclusion criteria were: Late(> 4 wk) reconstruction, open technique, isolated PCL reconstruction, knee degenerative disease, combinedfracture or vascular injury and use of allograft or autograft for PCL reconstruction. Clinical and functional outcomes were assessed with IKDC Subjective Knee Form, KOS-ADLS questionnaire, Lysholm scale and SF-12 Health Survey. Posterior displacement(PD) was measured with the Telos Stress Device. RESULTS Seven patients were excluded; two because of coexisting knee osteoarthritis and the remaining five because of failure to attend the final follow-up. The sample consisted of 31 patients with mean age at the time of reconstruction 33.2 ± 12.5 years(range 17-61). The postoperative follow-up was on average 9.27 ± 4.27 years(range 5-18). The mean average IKDC and KOS scores were 79.32 ± 17.1 and 88.1 ± 12.47% respectively. Average PD was 3.61 ± 2.15 mm compared to 0.91 ± 1.17 mm in the uninjured knees(one with grade 1+ and two with grade 2 +). Dial test was found positive in one patient, whereas the quadriceps active drawer test was positive in three patients. None was tested positive on the reverse-pivot shift test. The range of motion(ROM) was normal in thirty knees, in comparison with the contralateral one. There was no extension deficit. Osteoarthritic changes were found in three knees(9.6%).CONCLUSION Early treatment of complex knee injuries, using LARS artificial ligament for PCL reconstruction sufficiently reduces posterior tibia displacement and provides satisfactory long-term functional outcomes.

Computation of satellite clock-ephemeris augmentation parameters for dual-frequency multi-constellation satellite-based augmentation system

Dual-frequency multi-constellation(DFMC) satellitebased augmentation system(SBAS) does not broadcast fast correction, which is important in reducing range error in L1-only SBAS.Meanwhile, the integrity bound of a satellite at low elevation is so loose that the service availability is decreased near the boundary of the service area. Therefore, the computation of satellite clockephemeris(SCE) augmentation parameters needs improvement.We propose a method introducing SCE prediction to eliminate most of the SCE error resulting from global navigation satellite system GNSS broadcast message. Compared with the signal-inspace(SIS) after applying augmentation parameters broadcast by the wide area augmentation system(WAAS), SIS accuracy after applying augmentation parameters computed by the proposed algorithm is improved and SIS integrity is ensured. With global positioning system(GPS) only, the availability of category-I(CAT-I)with a vertical alert level of 15 m in continental United States is about 90%, while the availability in the other part of the WAAS service area is markedly improved. With measurements made by the stations from the crustal movement observation network of China,users in some part of China can obtain CAT-I(vertical alert limit is 15 m) service with GPS and global navigation satellite system(GLONASS).

Design of robust stability augmentation system for an airship using genetic algorithm

This paper presents the design of stability augmentation system (SAS) for the airship, which is robust with respect to parametric plant uncertainties. A robust pole placement approach is adopted in the design, which uses genetic algorithm (GA) as the optimization tool to derive the most robust solution of the state-feedback gain matrix K. The method can guarantee the resulting closed-loop poles to remain in a specified allocation region despite plant parameter uncertainty. Thus, the longitudinal stability of the airship is augmented by robustly assigning the closed-loop poles in a prescribed region of the left half s-plane.

Ligament augmentation reconstruction system artificial ligaments in patellar tendon reconstruction-a chronic patellar tendon rupture after multiple operations: A case report

BACKGROUND Patellar tendon rupture is a rare disease,and reports regarding patellar tendon reconstruction with ligament augmentation reconstruction system(LARS)ligaments are limited,with only three reports available in the literature.LARS ligaments are made of polyethylene terephthalate and have been certified as a more favorable option than other tendon transplants.To our knowledge,this is the first report of patellar tendon reconstruction with LARS for suture fixation due to poor quality of the tendon after multiple operations to enable early mobilization and quick rehabilitation.CASE SUMMARY A 65-year-old woman had limited ability in extending her leg and an inability to perform a straight leg raise after multiple operations due to patella fracture.The patient underwent patellar tendon reconstruction with LARS artificial ligaments.After 12 mo of follow-up,the patient was able to perform a straight leg raise,and the incision healed well without complications.The Lysholmscore was 95 and the range of motion of the knee was 0-130°.CONCLUSION This study revealed that patellar tendon reconstruction with LARS artificial ligaments is possible in a patient with a patellar tendon rupture who required rapid postoperative recovery.

Synchronization of the fractional-order generalized augmented L u¨system and its circuit implementation

In this paper, the synchronization of the fractional-order generalized augmented Lti system is investigated. Based on the predictor--corrector method, we obtain phase portraits, bifurcation diagrams, Lyapunov exponent spectra, and Poincar6 maps of the fractional-order system and find that a four-wing chaotic attractor exists in the system when the system pa- rameters change within certain ranges. Further, by varying the system parameters, rich dynamical behaviors occur in the 2.7-order system. According to the stability theory of a fractional-order linear system, and adopting the linearization by feedback method, we have designed a nonlinear feedback controller in our theoretical analysis to implement the synchro- nization of the drive system with the response system. In addition, the synchronization is also shown by an electronic circuit implementation for the 2.7-order system. The obtained experiment results accord with the theoretical analyses, which further demonstrate the feasibility and effectiveness of the proposed synchronization scheme.

Sliding-mode observers for systems with unknown inputs and measurement disturbances

The method to design sliding-mode observers for systems with unknown inputs and measurement disturbances is presented in the paper. An augmented system is constructed by viewing the measurement disturbances as unknow inputs. For such an augmented system, the so-called observer matching condition is not satisfied. Based on the construction of auxiliary outputs, the observer matching condition may be satisfied. High-order sliding-mode differentiators are developed to obtain the estimates of those unmeasurable variables contained in the auxiliary output vector. Employing the estimate of auxiliary output vector, a sliding-mode observer is designed. The simulation results to a real model show that the proposed method is effective.

Smart phone-based context-aware augmentative and alternative communications system

A smartphone-based context-aware augmentative and alternative communication(AAC) was applied was in order to enhance the user's experience by providing simple, adaptive, and intuitive interfaces. Various potential context-aware technologies and AAC usage scenarios were studied, and an efficient communication system was developed by combining smartphone's multimedia functions and its optimized sensor technologies. The experimental results show that context-awareness accuracy is achieved up to 97%.

Modified iterative method for augmented system

The successive overrelaxation-like （SOR-like） method with the real param- eters ω is considered for solving the augmented system. The new method is called the modified SOR-like （MSOR-like） method. The functional equation between the parameters and the eigenvalues of the iteration matrix of the MSOR-like method is given. Therefore, the necessary and sufficient condition for the convergence of the MSOR-like method is derived. The optimal iteration parameter ω of the MSOR-like method is derived. Finally, the proof of theorem and numerical computation based on a particular linear system are given, which clearly show that the MSOR-like method outperforms the SOR-like （Li, C. J., Li, B. J., and Evans, D. J. Optimum accelerated parameter for the GSOR method. Neural, Parallel ＆ Scientific Computations, 7（4）, 453-462 （1999）） and the modified sym- metric SOR-like （MSSOR-like） methods （Wu, S. L., Huang, T. Z., and Zhao, X. L. A modified SSOR iterative method for augmented systems. Journal of Computational and Applied Mathematics, 228（4）, 424-433 （2009））.

Optimization of multibody systems based on the generalized-α projection method for DAEs

Efficient optimization strategy of multibody systems is developed in this paper. Aug- mented Lagrange method is used to transform constrained optimal problem into unconstrained form firstly. Then methods based on second order sensitivity are used to solve the unconstrained problem, where the sensitivity is solved by hybrid method. Generalized-α method and generalized-α projection method for the differential-algebraic equation, which shows more efficient properties with the lager time step, are presented to get state variables and adjoint variables during the optimization procedure. Numerical results validate the accuracy and efficiency of the methods is presented.

基于极值理论的地基增强系统完好性评估方法

针对地基增强系统(Ground Based Augmentation System,GBAS)完好性风险事件的极端性而导致的无法通过风险事件发生频率评估系统性能的问题,提出一种基于极值理论的GBAS完好性评估方法。根据机载端(位置域)输出的位置误差和保护级计算安全系数,并利用区间极大值模型对安全系数进行建模描述以获得其分布模型;利用极大似然法估计安全系数模型参数,进而利用模型外推法计算GBAS完好性风险值。给出GBAS完好性评估流程,并利用GBAS系统进行了验证实验。研究结果表明:对于C类GBAS进近服务而言,基于全球定位系统(Global Position System,GPS)增强GBAS和基于北斗卫星导航系统(Beidou Navigation Satellite System,BDS)增强GBAS可用性均大于99.9999%;对于F类GBAS进近服务而言,BDS GBAS可用性能要优于GPS GBAS;根据7 d观测数据外推得到的GPS GBAS垂直和侧向完好性风险值分别为4.557×10^(-8)/进近和5.152×10^(-8)/进近,BDS GBAS垂直和侧向完好性风险值分别为1.612×10^(-7)/进近和1.823×10^(-7)/进近,满足航空器终端区I类进近与着陆导航性能需求。

基于增强现实技术的高校工科专业实践仿真教学系统设计

为满足高校工科学生的实践教学需求,设计基于增强现实技术的仿真教学系统,通过高性能硬件和增强现实(Augmented Reality,AR)技术实现互动式实验操作模拟、虚拟物体渲染与交互。实验表明,该系统能为学生带来更丰富、直观的虚拟学习体验,提升其学习兴趣和效果。

磁共振成像影像导航及靶区选择在经颅磁刺激治疗中的应用

背景:在经颅磁刺激临床实际应用中,是否能准确瞄准刺激脑区可影响经颅磁刺激的实际治疗效果。近年来,随着神经导航系统、移动式增强现实技术的发展,以及多种不同模态磁共振成像数据分析方法的出现,刺激靶区定位的准确性和靶区选择的优化有望得到进一步的提高。目的:综述基于磁共振成像的影像导航定位原理及在经颅磁刺激中的应用,归纳不同模态磁共振成像数据分析在指导经颅磁刺激靶区选择上的作用。方法:应用计算机在PubMed、中国知网和万方数据库检索相关文献,以“transcranial magnetic stimulation,coil positioning,neuronavigation,augmented reality,magnetic resonance imaging,经颅磁刺激,线圈定位,神经导航,增强现实,核磁共振成像,原理”为主要检索词,最终纳入63篇文献进行分析。结果与结论:①传统经颅磁刺激线圈放置方法中,“5 cm规则”、国际脑电10-20定位法最为常用,这些方法具有简便、经济的优点,但过于依赖操作者的经验,存在不同操作者的技术差异。②基于立体定向技术发展而来的神经导航系统是目前可视化程度及准确度最高的辅助经颅磁刺激线圈放置的引导方式,它通过MRI数据采集、脑三维重建、头模配准及立体几何定位等步骤来实现可视化定位,具有较高的临床治疗及科研应用价值,但因其设备较为昂贵,目前在医疗机构中尚未普及。③对于不同层次的医疗单位,移动式移动式增强现实技术不失为一种经济、高效的神经导航系统替代方案,它通过磁共振成像数据采集、构建二维/三维图像、虚拟图像与真实脑图像叠加来实现头皮下脑组织可视化定位,具有直观性强、成本低廉的优势,可在基层医疗单位推广应用。④尽管相对脑电10-20定位策略,可视化定位的临床疗效优越性目前尚未充分体现,但随着研究者对人脑多种不同模态磁共振成像扫描数据的挖掘,有望进一步优化经颅磁刺激治疗靶区选择的策略,提高经颅磁刺激治疗应答率和个性化程度,这在将来是极具潜力和挑战的研究方向。

基于样本增强的列车卫星定位伪距欺骗检测方法

基于卫星导航的列车自主定位是列车控制系统等铁路关键装备的重要技术方向。然而,列车卫星定位面临诸多挑战,除信号可视性问题和多径效应之外,来自系统外部的蓄意欺骗等干扰攻击,会对定位功能及性能产生直接威胁。为此,本文以基于全球导航卫星系统(GNSS)的列车定位面临的伪距欺骗这一典型干扰模式为对象,研究并提出一种基于样本增强的伪距欺骗主动检测方法。该方法运用Wasserstein生成式对抗网络(WGAN)解决受欺骗干扰样本数据不均衡问题,利用扩充的数据集训练检测模型,并引入自注意力(SA)机制优化来自不同接收机输入特征之间的相对位置关系,采用生成式对抗学习思想形成一套完整的列车卫星定位伪距欺骗干扰检测方案。由列车卫星定位欺骗干扰注入测试结果可知,提出的方法能够充分运用生成式对抗网络思想解决受欺骗样本的典型受限问题,融合自注意力机制所得检测性能显著优于载噪比检测和代表性机器学习算法等常规检测方案;对建模样本未覆盖特征具备良好的适应能力,具有更优的检测精度和鲁棒性,在多个伪距欺骗干扰模式数据集上测试所得F1分数均超过0.99。该方法在欺骗干扰检测性能方面的优势能够为众多卫星导航系统铁路应用提供有力支撑,为有效防范卫星定位在信息安全层面的攻击入侵提供了有利条件。

人工智能在新型电力系统智能传感、通信与数据处理领域应用

新型电力系统以清洁能源为主体,借助海量数据和计算技术实现电源与负荷间的动态平衡,其核心特征是系统的可观、可测、可控。人工智能作为重要技术支撑,能够在能量流和信息流深度融合的基础上,提升电网智能感知水平,优化通信网资源利用和系统数据处理能力。该文主要介绍了新型电力系统的形态、特征和机理,强调了在新形势下的电网数字化转型迫切需求,并对人工智能技术在电力传感、电力通信和电力大数据处理领域的研究现状和应用情况进行梳理分析,探究其促进新型电力系统各环节电气量、状态量、环境量的全面感知、即时通信与数据分析,有力支撑电力高级应用。最后对人工智能技术在新型电力系统建设中面临的挑战进行了总结和技术发展展望。

智慧动物与电子科技交互:现状与展望

人类与动物的交互合作自古以来就有着悠久的历史,伴随着智能芯片、可穿戴设备和机器算法的快速发展,智慧动物与电子科技的交互成为了现实。如今,人类可以借助电子系统与动物进行沟通、感知和控制。这类电子设备的目标在于实现以动物为中心的工作模式,从而提升人类对动物的理解,最终促进动物智能和创造力的发展。本文将中型、大型动物作为研究对象,以发展其能力增强为目标,提出了“智慧动物增强系统”的构想。该构想用以描述这类装置的特性,并对现有的动物与计算机接口解决方案进行了全面综述。总的来说,智慧动物增强系统主要分为植入式和非植入式两类,均由接口平台、感知与解读、控制与指示三部分构成,并通过不同层次的增强系统和架构模式,从而实现人与动物的智慧交互。尽管已有的智慧动物增强系统仍然缺乏完整独立的交互系统架构,但在未来的发展中,智慧动物增强系统具备良好的前景和发展空间,不仅可以用于替代尖端设备和运输设备,还有望通过智慧共联实现跨物种的信息交互。同时,智慧动物增强系统可以促进人与动物的双向交互,对动物伦理和生态保护的发展也将产生重要的推动作用。更为重要的是,基于动物主体的交互模型开发能够为设计人机交互系统提供可借鉴的研究经验,从而有助于更高效地推进人机结合宏伟目标的早日实现。

Assessment of corrected time-step method for nominal ionospheric gradient calculation: A comparative analysis with spatial approaches

The effect of ionospheric delay on the ground-based augmentation system under normal conditions can be mitigated by determining the value of the nominal ionospheric gradient(σvig).The nominal ionospheric gradient is generally obtained from Continuously Operating Reference Stations data by using the spatial single-difference method(mixed-pair,station-pair,or satellite-pair)or the temporal single-difference method(time-step).The time-step method uses only a single receiver,but it still contains ionospheric temporal variations.We introduce a corrected time-step method using a fixed-ionospheric pierce point from the geostationary equatorial orbit satellite and test it through simulations based on the global ionospheric model.We also investigate the effect of satellite paths on the corrected time-step method in the region of the equator,which tends to be in a more north–south direction and to have less coverage for the east–west ionospheric gradient.This study also addresses the limitations of temporal variation correction coverage and recommends using only the correction from self-observations.All processes are developed under simulations because observational data are still difficult to obtain.Our findings demonstrate that the corrected time-step method yieldsσvig values consistent with other approaches.

纳米SiO_(2)微乳液对鄂南致密油藏的降压增注效果

红河油田长8油藏断裂结构复杂,属于低孔超低渗油藏,储层非均质性强,且基质残余油饱和度高,水相渗透率低,注水压力上升速度快,已超过裂缝重启压力,水窜现象严重,注水开发效果差。结合纳米粒子与微乳液特性设计了一种纳米SiO_(2)微乳液降压增注体系,系统评价了该体系耐温性、降低界面张力能力、增溶性及与地层配伍性,并开展了岩心降压增注驱替实验。实验结果表明,该纳米SiO_(2)微乳液体系不仅抗温、抗盐性良好,且界面活性高,油水界面张力可降至10^(-2)mN/m左右;纳米SiO_(2)微乳液体系的油增溶性能良好,增溶量达到6.5 mL/30 mL。岩心降压增注实验结果显示,向水测渗透率约为0.4×10^(-3)μm^(2)的岩心中注入2 PV质量分数为1%的纳米SiO_(2)微乳液体系,降压效率达到28%以上,降压增注效果明显,能满足现场需求。

无负采样的正样本增强图对比学习推荐方法PAGCL

对比学习(CL)因能够提取数据本身包含的监督信号而被广泛应用于推荐任务。最近的研究表明,CL在推荐方面的成功依赖于对比损失——互信息噪声对比估计(InfoNCE)损失带来的节点分布的均匀性。此外,另一项研究证明贝叶斯个性化排序(BPR)损失的正项与负项分别带来的对齐性和均匀性有助于提高推荐性能。由于在CL框架中对比损失能够带来比BPR负项更强的均匀性,BPR负项存在的必要性值得商榷。实验分析表明在对比框架中BPR的负项是不必要的,并基于这一观察提出了无需负采样的联合优化损失,可应用于经典的CL方法并达到相同或更高的性能。此外,与专注于提高均匀性的研究不同,为进一步加强对齐性,提出一种新颖的正样本增强的图对比学习方法(PAGCL),该方法使用随机正样本在节点表示层面进行扰动。在多个基准数据集上的实验结果表明,PAGCL在召回率及归一化折损累积增益(NDCG)这两个常用指标上均优于SOTA方法自监督图学习(SGL)、简单图对比学习(SimGCL)等,且相较于基模型轻量化图卷积(LightGCN)的NDCG@20提升最大可达17.6%。