With the fast development of online and mobile technologies, individualized or personalized learning is becoming increasingly important. Online courses especially Massive Open Online Courses (MOOCs) often have student...
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With the fast development of online and mobile technologies, individualized or personalized learning is becoming increasingly important. Online courses especially Massive Open Online Courses (MOOCs) often have students from many countries, with different prior knowledge, expectations, and skills. They in particular could benefit from learning materials or learning systems that are customized to meet their needs. On this note, this paper suggests a personalized recommendation system for learners in online courses. The system recommends learning resources such as relevant courses to learners enrolled in formal online courses, by using a combination of association rules, content filtering, and collaborative filtering. Pilot testing of this system in the Shanghai Lifelong Learning Network, a platform for free and open education, indicates that this recommendation system can improve the utilization rate of educational resources and also promote the learning autonomy and efficiency of students.
In recent years, the software system of computers is increasingly developed. However, most of China's current software projects have encountered the problems of over-expenditure and postponing, which causes a grea...
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In recent years, the software system of computers is increasingly developed. However, most of China's current software projects have encountered the problems of over-expenditure and postponing, which causes a great loss, so it urgently calls for estimating the cost of researching and developing software. In this paper, the existing software algorithm models have been analyzed in the problems of model structure and factor, software environment and a new model of cost estimation with combinational algorithm model is established on the basis of GAHP and algorithm model. It compares group decision weighting method with iteration AHP group decision weighting method, and draws a conclusion that HP group decision weighting method has the smallest inaccurate value between software cost data and actual data. It is expected to overcome the shortages of different algorithm models for more accurate and flexible software cost estimation.
In this paper, we present a combinational efficient algorithm for solving second-order elliptic ordinary differential equation eigenvalue problems on four kinds of meshes. Firstly, a combinational scheme is proposed b...
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In this paper, we present a combinational efficient algorithm for solving second-order elliptic ordinary differential equation eigenvalue problems on four kinds of meshes. Firstly, a combinational scheme is proposed by leveraging the linear finite element scheme and the second-order finite difference scheme based on mass lumping method. An efficient algorithm is constructed by using the combinational scheme with a constant combined parameter. Then, we improve the efficient algorithm by computing the quasi-optimal combined parameters for different eigenvalues. Finally, numerical experiments tested on both uniform and nonuniform meshes are shown to illustrate the efficiency of our algorithms.
In complex systems,functional dependency and physical dependency may have a coupling *** this paper,the reliability of a k-out-of-n system is analyzed considering load-sharing effect and failure mechanism(FM)*** types...
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In complex systems,functional dependency and physical dependency may have a coupling *** this paper,the reliability of a k-out-of-n system is analyzed considering load-sharing effect and failure mechanism(FM)*** types of FMs are considered and an accumulative damage model is proposed to illustrate the system behavior of the k-out-of-n system and the coupling effect between load-sharing effect and FM propagation effect.A combinational algorithm based on Binary decision diagram(BDD)and Monte-Carlo simulation is presented to evaluate the complex system behavior and reliability of the k-out-of-n system.A current stabilizing system that consists of a 3-out-of-6 subsystem with FM propagation effect is presented as a case to illustrate the complex behavior and to verify the applicability of the proposed *** to the coupling effect change,the main mechanism and failure mode will be changed,and the system lifetime is *** are analyzed and results show that different sensitivity factors of three different FMs lead to the change of the development rate,thus changing the failure *** the coupling effect may lead to an incomplete and ineffective measuring and monitoring *** strategies must be adopted to make the FM propagation insensitive to load-sharing effect.
Dependent competing failure process (DCFP) has been widely studied in recent years. When evaluating the reliability of DCFP system, the aleatory uncertainty due to randomness and the epistemic uncertainty due to lack ...
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Dependent competing failure process (DCFP) has been widely studied in recent years. When evaluating the reliability of DCFP system, the aleatory uncertainty due to randomness and the epistemic uncertainty due to lack of data and knowledge should be considered. In this paper, the hybrid uncertainty of DCFP system is analyzed and quantified with chance theory. The uncertainty random renewal reward process and the arithmetic Liu process are used to describe the shock and degradation process. The quantification of uncertainty propagation is realized by decoupling DCFP from the physical correlation aspect. Reliability of DCFP system considering two kinds of unilateral dependencies and mutual dependency is modeled and a combinational algorithm is proposed to solve it. Finally, the DCFP effect in control system of an aircraft is studied as a case, aleatory uncertainty and epistemic uncertainty are modeled, and the system reliability is evaluated. Meanwhile, the effects of key pa-rameters on system reliability are discussed. Results show that the chance theory is an appropriate method to qualify the hybrid uncertainty for engineering systems when data is insufficient. The mutual dependency of soft failure and hard failure will reduce the system reliability. The smaller the parameter of hard failure, the greater the influence of mutual dependency on the results.
As people depend more and more on softwares, there has been an increasing demand for the trustworthiness of the software. To measure the trustworthiness of software, we need to design appropriate trustworthy metrics. ...
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As people depend more and more on softwares, there has been an increasing demand for the trustworthiness of the software. To measure the trustworthiness of software, we need to design appropriate trustworthy metrics. We once proposed four metric criteria for the multi-dimensional trustworthiness of the software and a metric model which satisfies these four criteria. In this paper, we describe a new metric model for the trustworthiness of the software which satisfies almost all these four criteria. Compared with the previous model, this model is better in the view of substitutivity. We also give a polynomial-time combinational algorithm for estimating the weight vectors appeared in the model based on the priority methods.
The stable marriage problem is a well-known problem of matching n men to n women to achieve a certain type of “stability;” the $O(n^2 )$ time Gale-Shapley [GS] algorithm for finding two particular, but extreme, stab...
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The stable marriage problem is a well-known problem of matching n men to n women to achieve a certain type of “stability;” the $O(n^2 )$ time Gale-Shapley [GS] algorithm for finding two particular, but extreme, stable marriages (out of a possibly exponential number of stable marriages) is also well known. In this paper we consider four problems concerned with finding information about the set of all stable marriages, and with finding stable marriages other than those obtained by the Gale-Shapley algorithm. In particular, we give an $O(n^2 )$ time algorithm which, for any problem instance of n men and n women, finds every man–woman pair that is contained in at least one stable marriage; we show that the same algorithm finds all the “rotations” for the problem instance in $O(n^2 )$ time; we give an $O(n^2 + n|S|)$ time and $O(n^2 )$ space bounded algorithm (which is time and space optimal) to enumerate all stable marriages, where S is the set of them; and we give an $O(n^2 )$ time algorithm to find the minimum regret stable marriage (the best marriage, as measured by the person who is worst off in it). We believe the previous best time bounds for these problems are respectively $O(n^4 )$ (from a related problem in [K]), $O(n^3 )$ [ILG], $O(n^3 |S|)$ [K] and $O(n^4)$ [K]. The basic idea leading to the improved running times is to exploit theorems about the structure of stable marriages in order to avoid back-up and duplicated work inherent in earlier algorithms.
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