科创中国

针对传统SVM主动学习中批量采样方法的不足,提出了动态可行域划分算法.从特征空间与参数空间的对偶关系入手,深入分析SVM主动学习的本质,将特征空间中对样本的标注视为参数空间中对可行域的划分;通过综合利用当前分类模型和先前标注样本两方面信息,动态地优化可行域划分方案,以确保选取的样本对模型改进的价值,最终实现更为高效的选择性采样.实验结果表明,基于动态可行域划分的SVM主动学习算法能够显著提高所选样本的信息量,从而能够在有限的标注代价下大幅提高其分类性能.

本研究调查了计算机辅助反馈策略对大学技术教育课程的影响.具体来说,研究探讨了计算机辅助反馈策略"对错反馈"(Knowledge of Responses,简称KCOR)和"正确答案反馈"(Knowledge of Correct Responses,简称KCR)的有效性,并与"无反馈"(No Feedback)的学生的学习态度进行了比较.三组学生被分配到三个条件之一:KOR,KCR和NR(对照组).通过四个星期的基于网络的教学实验,研究者获得学习者对计算机辅助反馈教学系略的态度.结果表明,学生对三种反馈显示出相同的态度.计算机辅助反馈策略可能是促进学习的可行的选择.

目前美国、韩国、中国台湾地区企业e-learning领域的发展走在世界前列.本文主要采用文献分析方法,通过搜索ProQuest数据库及CNKI中文数据库的关键研究文献,及通过梳理国际知名研究机构Bersin & Associates、ASTD、Brandon-hall等的研究报告,系统分析了这些国家和地区的企业e-learning 现状,并且对其发展趋势做了研究与预测.文章最后对我国企业e-learning发展提出了相应的政策建议.

Due to the large variations of environment with ever-changing background and vehicles with different shapes, colors and appearances, to implement a real-time on-board vehicle recognition system with high adaptability, efficiency and robustness in complicated environments, remains challenging. This paper introduces a simultaneous detection and tracking framework for robust on-board vehicle recognition based on monocular vision technology. The framework utilizes a novel layered machine learning and particle filter to build a multi-vehicle detection and tracking system. In the vehicle detection stage, a layered machine learning method is presented, which combines coarse-search and fine-search to obtain the target using the Ada Boost-based training algorithm. The pavement segmentation method based on characteristic similarity is proposed to estimate the most likely pavement area. Efficiency and accuracy are enhanced by restricting vehicle detection within the downsized area of pavement. In vehicle tracking stage, a multi-objective tracking algorithm based on target state management and particle filter is proposed. The proposed system is evaluated by roadway video captured in a variety of traffics, illumination, and weather conditions. The evaluating results show that, under conditions of proper illumination and clear vehicle appearance, the proposed system achieves 91.2% detection rate and 2.6% false detection rate. Experiments compared to typical algorithms show that, the presented algorithm reduces the false detection rate nearly by half at the cost of decreasing 2.7%–8.6% detection rate. This paper proposes a multi-vehicle detection and tracking system, which is promising for implementation in an on-board vehicle recognition system with high precision, strong robustness and low computational cost.

The existing research of the active suspension system(ASS) mainly focuses on the different evaluation indexes and control strategies. Among the different components, the nonlinear characteristics of practical systems and control are usually not considered for vehicle lateral dynamics. But the vehicle model has some shortages on tyre model with side-slip angle, road adhesion coefficient, vertical load and velocity. In this paper, the nonlinear dynamic model of lateral system is considered and also the adaptive neural network of tire is introduced. By nonlinear analysis methods, such as the bifurcation diagram and Lyapunov exponent, it has shown that the lateral dynamics exhibits complicated motions with the forward speed. Then, a fuzzy control method is applied to the lateral system aiming to convert chaos into periodic motion using the linear-state feedback of an available lateral force with changing tire load. Finally, the rapid control prototyping is built to conduct the real vehicle test. By comparison of time response diagram, phase portraits and Lyapunov exponents at different work conditions, the results on step input and S-shaped road indicate that the slip angle and yaw velocity of lateral dynamics enter into stable domain and the results of test are consistent to the simulation and verified the correctness of simulation. And the Lyapunov exponents of the closed-loop system are becoming from positive to negative. This research proposes a fuzzy control method which has sufficient suppress chaotic motions as an effective active suspension system.

In the prediction of active vibration isolation performance,control force requirements were ignored in previous work.This may limit the realization of theoretically predicted isolation performance if control force of large magnitude cannot be supplied by actuators.The behavior of a feed-forward active isolation system subjected to actuator output constraints is investigated.Distributed parameter models are developed to analyze the system response,and to produce a transfer matrix for the design of an integrated passive-active isolation system.Cost functions comprising a combination of the vibration transmission energy and the sum of the squared control forces are proposed.The example system considered is a rigid body connected to a simply supported plate via two passive-active isolation mounts.Vertical and transverse forces as well as a rotational moment are applied at the rigid body,and resonances excited in elastic mounts and the supporting plate are analyzed.The overall isolation performance is evaluated by numerical simulation.The simulation results are then compared with those obtained using unconstrained control strategies.In addition,the effects of waves in elastic mounts are analyzed.It is shown that the control strategies which rely on unconstrained actuator outputs may give substantial power transmission reductions over a wide frequency range,but also require large control force amplitudes to control excited vibration modes of the system.Expected power transmission reductions for modified control strategies that incorporate constrained actuator outputs are considerably less than typical reductions with unconstrained actuator outputs.In the frequency range in which rigid body modes are present,the control strategies can only achieve 5–10 dB power transmission reduction,when control forces are constrained to be the same order of the magnitude as the primary vertical force.The resonances of the elastic mounts result in a notable increase of power transmission in high frequency range and cannot be attenuated by active control.The investigation provides a guideline for design and evaluation of active vibration isolation systems.

目的 研究艾滋病(AIDS)患者高效抗反转录病毒治疗(HAART)后对血脂水平的影响.方法 回顾性调查2005年6月~2011年5月在我科门诊应用高效抗反转录病毒治疗的HIV/AIDS患者100例,平均抗病毒治疗时间(40.78±20.09)个月,HAART方案分别为AZT+ 3TC+ NVP、AZT+ 3TC+ EFV、D4T+ 3TC+ NVP和D4T+ 3TC+ EFV4种,其中D4T+ 3TC+ NVP方案组中体重>60 kg者,D4T的剂量为每次40 mg,每日2次;体重<60 kg者,D4T的剂量为每次30 mg,每日2次.对4组患者治疗前后CD4淋巴细胞计数、空腹血脂(包括总胆固醇、三酰甘油、高密度脂蛋白胆固醇、低密度脂蛋白胆固醇)进行比较.结果 HAART后,CD4淋巴细胞计数均升高,总胆固醇、三酰甘油上升,高密度脂蛋白、低密度脂蛋白正常,AZT方案组与D4T方案组比较差异有统计学意义(P<0.05);其中D4T +3TC+ NVP方案组中,体重>60kg、D4T的剂量为每次40 mg与体重<60 kg、D4T的剂量为每次30 mg比较差异有统计学意义(P<0.05);静脉吸毒与性传播所致艾滋病感染,对血脂无明显影响.结论 HAART治疗对5组患者均有效,以D4T为主的HAART治疗方案可引起血脂代谢异常.

在分析社会标注对网络学习资源揭示的可行性基础上,从社会标注对网络学习资源的扩展揭示能力、不同教育资源网站中的标签揭示能力及教育领域标签与关键词揭示能力比较三个实证角度分析社会标注对网络学习资源的揭示能力,并提出社会标注揭示网络学习资源的多维模型.

The mass production of printed electronics can be achieved by roll-to-roll(R2R) printing system, so highly accurate web tension is required that can minimize the register error and keep the thickness and roughness of printed devices in limits. The web tension of a R2R system is regulated by the use of integrated load cells and active dancer system for printed electronics applications using decentralized multi-input-single-output(MISO) regularized variable learning rate backpropagation artificial neural networks. The active dancer system is used before printing system to reduce disturbances in the web tension of process span. The classical PID control result in tension spikes with the change in roll diameter of winder and unwinder rolls. The presence of dancer in R2R system shows that improved web tension control in printing span and the web tension can be enhanced from 3.75 N to 4.75 N. The overshoot of system is less than ±2.5 N and steady state error is within ±1 N where load cells have a signal noise of ±0.7 N. The integration of load cells and active dancer with self-adapting neural network control provide a solution to the web tension control of multispan roll-to-roll system.

入学数学准备是预测儿童小学学业成绩的有力指标,提高儿童的入学数学准备水平有助于提高儿童入学后的学业成绩、缩小儿童学习与发展的阶层差距和城乡差距.对浙江、江西、四川三省的1181名学前一年幼儿入学数学准备状况的城乡差异比较发现,城乡学前一年幼儿的数学学习与发展普遍存在不同步、不均衡的现象,关系领域的学习落后于数、量、形、空间等领域的学习;总体上,城市幼儿在多个领域的表现都优于乡镇和农村幼儿,城市幼儿与县城幼儿的表现没有显著差异.在普及学前教育发展的过程中,应加强对乡镇和农村幼儿的早期补偿教育,并加强关系领域的教学.