A study of barriers to online learning in distance education in China

China's 'Modern Distance Education' is a government-led initiative prompted by the need to widen access to higher education and by the opportunities offered by the development of a widespread infrastructure of information and communications technologies. Distance education using television, radio and other technologies has a long history in China, but the advent of computer communications opened new possibilities for promoting educational development and the policy goal of modernisation. Distance education in China now involves online learning, to various degrees. However, the effectiveness of online courses depends on learners accessing them and using the resources provided. Does this happen? How well do learners manage their online learning? What barriers do they encounter? This thesis examines these questions through a study of adult distance learners based on analysis of a survey of 2931 learners and in-depth interviews with 21 learners and distance education experts in several locations. I find that: (1) The barriers to online learning faced by the sample learners are of seven types: communication and interaction; teaching and courses; learning resources; learning support services; external support and economic burdens; computer and network operation skills; and conditions for accessing the Internet. (2) Among the seven types of barrier, the 'communication and interaction' barrier is not only acting as the most important one faced by these learners, but also exists as a markedly independent one. (3) Improvements in 'communication and interaction' are the most effective in overcoming the other barriers and also contribute to increasing the learners' learning efficiency. This leads to the perception that working on 'communication and interaction' is very likely to be the best starting point for tackling barriers to online learning. According to these findings, I believe that if the situation of 'communication and interaction' in online learning can be improved for online learners to meet their desire for 'sociability', and once they can thus establish their own 'learning communities' and form relatively stable 'student-to-student' relationships, and 'student-to-teacher' relationships, other learning barriers will be reduced as well. Hence, I argue that we should always pay attention to making 'communication and interaction' occur effectively for online learners in the learning process. We should consider the matter of 'interaction' not only in the delivery process of teaching and tutoring as well as in learning activities, but also in the production of teaching materials and in the provision of learning materials, as well as in the building of learning environments. In a word, it is necessary to put the whole matter of 'interaction' at the core of the instructional system design for online learning

A study of barriers to online learning in distance education in China

China's 'Modern Distance Education' is a government-led initiative prompted by the need to widen access to higher education and by the opportunities offered by the development of a widespread infrastructure of information and communications technologies. Distance education using television, radio and other technologies has a long history in China, but the advent of computer communications opened new possibilities for promoting educational development and the policy goal of modernisation. Distance education in China now involves online learning, to various degrees. However, the effectiveness of online courses depends on learners accessing them and using the resources provided. Does this happen? How well do learners manage their online learning? What barriers do they encounter? This thesis examines these questions through a study of adult distance learners based on analysis of a survey of 2931 learners and in-depth interviews with 21 learners and distance education experts in several locations. I find that: (1) The barriers to online learning faced by the sample learners are of seven types: communication and interaction; teaching and courses; learning resources; learning support services; external support and economic burdens; computer and network operation skills; and conditions for accessing the Internet. (2) Among the seven types of barrier, the 'communication and interaction' barrier is not only acting as the most important one faced by these learners, but also exists as a markedly independent one. (3) Improvements in 'communication and interaction' are the most effective in overcoming the other barriers and also contribute to increasing the learners' learning efficiency. This leads to the perception that working on 'communication and interaction' is very likely to be the best starting point for tackling barriers to online learning. According to these findings, I believe that if the situation of 'communication and interaction' in online learning can be improved for online learners to meet their desire for 'sociability', and once they can thus establish their own 'learning communities' and form relatively stable 'student-to-student' relationships, and 'student-to-teacher' relationships, other learning barriers will be reduced as well. Hence, I argue that we should always pay attention to making 'communication and interaction' occur effectively for online learners in the learning process. We should consider the matter of 'interaction' not only in the delivery process of teaching and tutoring as well as in learning activities, but also in the production of teaching materials and in the provision of learning materials, as well as in the building of learning environments. In a word, it is necessary to put the whole matter of 'interaction' at the core of the instructional system design for online learning

Multiscale isogeometric optimization for cellular structure with multiple prototypes

This paper presents a multiscale concurrent isogeometric design method for the cellular structure composed of the multiple prototype microstructures. Based on the unified-skeleton modeling scheme, the graded microstructures obtained from a same prototype have similar topology and good connectivity between each other. For the different prototypes, the configurations are rearranged and added the thin-wall material in common interfaces. Thus, the geometric features as well as the structural skeletons can have a smooth transition. Through combining the numerical homogenization method with the interpolation technique, the effective properties of graded microstructures can be estimated efficiently. For the multiscale scheme, the allocation of microstructures is optimized by a material distribution-based method while the configurations of prototypes are designed by the isogeometric parameterized level set method. The proposed method inherits the high accuracy and high efficiency of isogeometric analysis and the smooth boundaries and distinct interfaces of level set method. The cellular structure can be freely customized with favorable connectivity

Phenomic selection in slash pine multi-temporally using UAV-multispectral imagery

Genomic selection (GS) is an option for plant domestication that offers high efficiency in improving genetics. However, GS is often not feasible for long-lived tree species with large and complex genomes. In this paper, we investigated UAV multispectral imagery in time series to evaluate genetic variation in tree growth and developed a new predictive approach that is independent of sequencing or pedigrees based on multispectral imagery plus vegetation indices (VIs) for slash pine. Results show that temporal factors have a strong influence on the h2 of tree growth traits. High genetic correlations were found in most months, and genetic gain also showed a slight influence on the time series. Using a consistent ranking of family breeding values, optimal slash pine families were selected, obtaining a promising and reliable predictive ability based on multispectral+VIs (MV) alone or on the combination of pedigree and MV. The highest predictive value, ranging from 0.52 to 0.56, was found in July. The methods described in this paper provide new approaches for phenotypic selection (PS) using high-throughput multispectral unmanned aerial vehicle (UAV) technology, which could potentially be used to reduce the generation time for conifer species and increase the genetic granularity independent of sequencing or pedigrees

Effects of biogenic amines on the testicular development in mud crabs Scylla serrata

英文摘要】 The regulation of three biogenic amines over the reproductive neuroendocrine activity of the male Scylla serrata was investigated by in vivo injection and in vitro incubation. The testicular index, the ratio of the mature sections in testes, and the ratio of Type B cells in androgenic gland were taken as the quantitative indexes. The in vivo injections indicated that: 5-HT can significantly promote the testicular development and the secretion of the androgenic gland in S. serrata; DA can inhibit the testicu..

Top scoring pairs for feature selection in machine learning and applications to cancer outcome prediction

<b>Background</b> The widely used k top scoring pair (k-TSP) algorithm is a simple yet powerful parameter-free classifier. It owes its success in many cancer microarray datasets to an effective feature selection algorithm that is based on relative expression ordering of gene pairs. However, its general robustness does not extend to some difficult datasets, such as those involving cancer outcome prediction, which may be due to the relatively simple voting scheme used by the classifier. We believe that the performance can be enhanced by separating its effective feature selection component and combining it with a powerful classifier such as the support vector machine (SVM). More generally the top scoring pairs generated by the k-TSP ranking algorithm can be used as a dimensionally reduced subspace for other machine learning classifiers.<p></p> <b>Results</b> We developed an approach integrating the k-TSP ranking algorithm (TSP) with other machine learning methods, allowing combination of the computationally efficient, multivariate feature ranking of k-TSP with multivariate classifiers such as SVM. We evaluated this hybrid scheme (k-TSP+SVM) in a range of simulated datasets with known data structures. As compared with other feature selection methods, such as a univariate method similar to Fisher's discriminant criterion (Fisher), or a recursive feature elimination embedded in SVM (RFE), TSP is increasingly more effective than the other two methods as the informative genes become progressively more correlated, which is demonstrated both in terms of the classification performance and the ability to recover true informative genes. We also applied this hybrid scheme to four cancer prognosis datasets, in which k-TSP+SVM outperforms k-TSP classifier in all datasets, and achieves either comparable or superior performance to that using SVM alone. In concurrence with what is observed in simulation, TSP appears to be a better feature selector than Fisher and RFE in some of the cancer datasets.<p></p> <b>Conclusions</b> The k-TSP ranking algorithm can be used as a computationally efficient, multivariate filter method for feature selection in machine learning. SVM in combination with k-TSP ranking algorithm outperforms k-TSP and SVM alone in simulated datasets and in some cancer prognosis datasets. Simulation studies suggest that as a feature selector, it is better tuned to certain data characteristics, i.e. correlations among informative genes, which is potentially interesting as an alternative feature ranking method in pathway analysis

A study of barriers to online learning in distance education in China

China's 'Modern Distance Education' is a government-led initiative prompted by the need to widen access to higher education and by the opportunities offered by the development of a widespread infrastructure of information and communications technologies. Distance education using television, radio and other technologies has a long history in China, but the advent of computer communications opened new possibilities for promoting educational development and the policy goal of modernisation. Distance education in Chi'na now involves online learning, to various degrees. However, the effectiveness of online courses depends on learners accessing them and using the resources provided. Does this happen? How well do learners manage their online learning? What barriers do they encounter? This thesis examines these questions through a study of adult distance learners based on analysis of a survey of 2931 learners and in -depth interviews with 21 learners and distance education experts in several locations. I find that: (1) The barriers to online learning faced by the sample learners are of seven types: communication and interaction; teaching and courses; learning resources; learning support services; external support and economic burdens; computer and network operation skills; and conditions for accessing the Internet. (2) Among the seven types of barrier, the 'communication and interaction' barrier is not only acting as the most important one faced by these learners, but also exists as a markedly independent one.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

The Stability Analysis of a Multi-Port Single-Phase Solid-State Transformer in the Electromagnetic Timescale

This paper proposes an overall practical stability assessment for a multi-port single-phase solid-state transformer (MS3T) in the electromagnetic timescale. When multiple stable subsystems are combined into one MS3T, the newly formed MS3T has a certain possibility to be unstable. Thus, this paper discusses the stability assessment of the MS3T in detail. First and foremost, the structure of the MS3T and its three stage control strategies are proposed. Furthermore, the stability analysis of each of the MS3T’s subsystems is achieved through the closed loop transfer function of each subsystem, respectively, including an AC-DC front-end side converter, dual active bridge (DAB) with a high-frequency (HF) or medium-frequency (MF) transformer, and back-end side incorporating DC-AC and dc-dc converters. Furthermore, the practical impedance stability criterion in the electromagnetic timescale, which only requires two current sensors and one external high-bandwidth small-signal sinusoidal perturbation current source, is proposed by the Gershgorin theorem and Kirchhoff laws. Finally, the overall stability assessment, based on a modified impedance criterion for the MS3T is investigated. The overall practical stability assessment of the MS3T can be validated through extensive simulation and hardware results