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Sheng-Che Hsiao Janet Mei-Chuen Lin Jiin-Cherng Kang 《美中教育评论》2011,(1):89-97
A quasi-experiment was conducted at an elementary school to investigate if guided collaboration would facilitate programming learning of 6 graders. Sixty-six students of two intact classes learned to program in KPL （kid＇s programming language） for 18 weeks during the experiment. One class was randomly assigned to the control group （i.e., free-collaboration） and the other to the experimental group （i.e., guided-collaboration）. Students in both groups formed heterogeneous teams of 3 persons. The guided-collaboration teams in experimental group were provided with a worksheet for every programming task. The worksheet contained a set of task-specific guiding questions to guide students through the problem-solving process in a systematic and disciplined manner. An analysis of test scores showed that the experimental group significantly outperformed the control group in the achievement tests, suggesting that the guiding questions were useful in enhancing students＇ comprehension of programming concepts and developing their programming skills. A comparison of the amount of time spent at each problem-solving step showed that the experimental group spent significantly more time than the control group at the analysis/design/coding step as well as the reflection step. Conversely, the control group spent considerably more time at the debugging step. With the help of the guiding questions, students in the experimental group were also more able to conduct meaningful discussions. 相似文献
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This paper presents a new genetic algorithm for the resource-constrained project scheduling problem(RCPSP).The algorithm employs a standardized random key(SRK) vector representation with an additional gene that determines whether the serial or parallel schedule generation scheme(SGS) is to be used as the decoding procedure.The iterative forward-backward improvement as the local search procedure is applied upon all generated solutions to schedule the project three times and obtain an SRK vector,which is rese... 相似文献
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Based on minimum output energy,an improved blind multiuser detection algorithm is proposed by the use of Hopfield neural network.Compared with traditional algorithms,the proposed algorithm does not need the circuit for constraints.The resources are greatly saved and the complexity is reduced as well.The simulation results show that the performance of the improved algorithm is similar to that of the optimal multiuser detection algorithm which is not suitable for the mobile station.Compared with the traditional gradient blind multiuser detection algorithm,the convergence speed of the improved algorithm is quickened. 相似文献
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Aiming to reduce fuel consumption and emissions of a dual-clutch hybrid electric vehicle during cold start, multi- objective optimization for fuel consumption and HC/CO emission from a TWC （three-way catalytic converter） outlet is presented in this paper. DP （dynamic programming） considering dual-state variables is proposed based on the Belhnan optimality principle. Both the battery SOC （state of charge） and the temperature of TWC monolith are considered in the algorithm simultaneously. In this way the global optimal control strategy and the Pareto optimal solution of multi-objective function are derived. Simulation results show that the proposed method is able to promote the TWC light-off significantly by decreasing the engine＇s load and improving exhaust temperature from the outlet of the engine, in comparison with original DP considering the single battery SOC. Compared to the results achieved by rule-based control strategy, fuel economy and emission of TWC outlet for cold start are optimized comprehensively. Each indicator of Pareto solution set shows the significant improvement. 相似文献
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This paper presents a quadratic programming method for optimal multi-degree reduction of Bézier curves with G1-continuity. The L2 and l2 measures of distances between the two curves are used as the objective functions. The two additional parameters, available from the coincidence of the oriented tangents, are constrained to be positive so as to satisfy the solvability condition. Finally, degree reduction is changed to solve a quadratic problem of two parameters with linear constraints. Applica- tions of degree reduction of Bézier curves with their parameterizations close to arc-length parameterizations are also discussed. 相似文献
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Environmental problems have received a great deal of attention in recent years.In particular,CO2 emissions worsen global warming and other environmental problems.The transport sector accounts for 20% of the total CO2 emissions.Therefore,the CO2 emission reduction of the transport sector is of great importance.In order to reduce emissions effectively,it is necessary to change the distribution and transportation processes.The purpose of this study is to minimize both the transportation costs and CO2 emissions during transportation.Our model considers a transportation scheduling problem in which loads are transported from an overseas production base to three domestic demand centers.The need for time-space networks arises naturally to improve the model.It is possible to know the distance carriers are moving,and also consider the timetables of carriers during transportation.Carrier choice,less-than carrier load,and domestic transportation among demand centers are considered as the three target areas to reduce CO2 emissions during the distribution process.The research model was formulated as a mixed integer programming （MIP） problem.It achieves cost reduction,and will contribute to improvement of the natural environment. 相似文献
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对于区间数线性规划的解法,从可信度的角度进行了一些初步的探讨。该方法能比较科学地确定参数的取值范围,也能得到较多的满意解,简化了以前算法的计算量,从而大大提高了解法的有效性。 相似文献
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The constrained Viterbi algorithm (C-VA) makes use of some prior reliable information to reduce complexity andimprove performance of Viterbi algorithm (VA). However it can only be used in the concatenate code scheme because thedetection result of cyclic redundancy check code (CRC) is exploited to provide reliable information. In this paper, a differentway is proposed to provide reliable information for C-VA, which is possible to be used in simple codec. Known bits were addedto the set partitioning in hierarchical trees (SPIHT) coded image sequence periodically and directly. They were thought to bereliable information for C-VA in the decoder. Experimental results show that the proposed scheme can obtain much bettererror resilient ability compared with conventional VA under the extremely inferior channel condition if the best desired qualityof reconstructed images can be sacrificed. 相似文献
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与开工时间有关的加工时间的超前有奖迟后受罚的排序问题的动态规划算法 总被引：1，自引：0，他引：1
In this paper, a single-machine scheduling model with a given common due date is considered. Job processing time is a linear decreasing function of its starting time. The objective function is to minimize the total weighted earliness award and tardiness penalty. Our aim is to find an optimal schedule so as to minimize the objective function. As the problem is NP-hard, some properties and polynomial time solvable cases of this problem are given. A dynamic programming algorithm for the general case of the problem is provided. 相似文献
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Least squares support vector machines （LS-SVMs） are modified support vector machines （SVMs） that involve equality constraints and work with a least squares cost function, which simplifies the optimization procedure. In this paper, a novel training algorithm based on total least squares （TLS） for an LS-SVM is presented and applied to multifunctional sensor signal reconstruction. For three different nonlinearities of a multifunctional sensor model, the reconstruction accuracies of input signals are 0.00136%, 0.03184% and 0.504 80%, respectively. The experimental results demonstrate the higher reliability and accuracy of the proposed method for multifunctional sensor signal reconstruction than the original LS-SVM training algorithm, and verify the feasibility and stability of the proposed method. 相似文献
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SVM方法是在统计学习理论的基础上发展起来的一种新的机器学习算法,它是统计学习理论的具体应用．讨论了SVM方法在故障诊断领域中应用的分类算法,并以滚动轴承为例进行了试验论证． 相似文献
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异常检测能够检测出数据中的异常情况,为各类系统正常运转提供重要支撑。提出一种基于变分自编码器的异常检测算法,该算法使用变分自编码器对输入数据进行特征提取,结合深度支持向量网络,压缩特征空间,并寻找最小超球体分离正常数据和异常数据,通过计算数据特征到超球体中心的欧式距离衡量数据的异常分数,并以此进行异常检测。在基准数据集MNIST和Fashion-MNIST上评估该算法,平均AUC分别达0.954和0.935,优于其它优秀算法。实验结果表明,该算法取得较好异常检测效果。 相似文献
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This paper considers a reentrant scheduling problem on parallel primary machines with a remote server machine, which is required to carry out the setup operation. In this problem, each job has three operations. The first and last operations are performed by the same primary machine, implying the reentrance, and the second operation is processed on the single server machine. The order of jobs is predetermined in our context. The challenge is to assign jobs to the primary machines to minimize the makespan. We develop a genetic algorithm（GA） to solve this problem. Based on a simple strategy of assigning jobs in batches on the parallel primary machines, the standardized random key vector representation is employed to split the jobs into batches. Comparisons among the proposed algorithm, the branch and bound（BB） algorithm and the heuristic algorithm, coordinated scheduling（CS）, which is only one heuristic algorithm to solve this problem in the literature, are made on the benchmark data. The computational experiments show that the proposed genetic algorithm outperforms the heuristic CS and the maximum relative improvement rate in the makespan is 1.66%. 相似文献
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支持向量机方法在解决小样本,非线性及高维模式识别中表现出许多特有的优势。目前主要用于二元分类问题中,而对于其在多类分类应用仍是一个值得研究的问题。在目前存在的各种多类支持向量机分类问题中,一对一方法是一种最符合实际的方法。文章提出了一种改进的支持向量机,并将其应用于图像分割。这种改进的支持向量机它对一对一方法进行了改进,实验表明,支持向量机的方法是一种很有潜力的图像分割技术。 相似文献
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在已有支持向量机的特征提取模型的基础上,通过引入一个向量函数,使原有的模型得到进一步改进,从而大大降低了问题的规模.文中给出了一种模拟退火算法求解得到的模型.该算法在传统的模拟退火算法的基础上增加了局部极小化和Markov链长度调整过程. 相似文献
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张燕 《商洛师范专科学校学报》2014,(4):38-41
为减少不均衡数据对支持向量机分类性能的影响,提出一种基于二次支持向量机的欠取样分类算法,该算法依据样本的分类超平面贡献大小对多数类样本进行欠取样．并对少数类样本进行过取样,重构训练数据集。该算法能够删除样本中的噪声数据。用控制参数控制删除样本的规模,实验表明,该算法能够提高支持向量机在不均衡数据集下的分类性能。 相似文献
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广义凸性和凸性在数学规划最优化理论以及最优化控制等很多数学领域中具有十分重要的作用,因此对凸性的研究和广义凸性的探索一直是凸分析的重要课题也是数学规划最重要的内容之一。基于B-凸性和半（E,F）-凸性,提出了一类新的广义凸性：半B-（E,F）-凸性,给出了半B-（E,F）-凸函数的概念,提出了半B-（E,F）-凸规划的概念,利用半B-（E,F）-凸规划的有关性质,讨论了半B-（E．F）-凸函数多目标规划的弱对偶定理。 相似文献
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1 Introduction The degree of malignancy in brain glioma[1]domi-nates the way of treatment .In case of gradeⅠorⅡaccording to Kernohan,the success rate of operationis satisfactory. Otherwise ,for gradeⅢor IV,the sur-gical risk is high ,and poor life qual… 相似文献