835 research outputs found
Fluid dynamics: an emerging route for the scalable production of graphene in the last five years
Bulk applications of graphene in fields such as advanced composites,
conductive ink, and energy storage require cheap and scalable graphene.
Fortunately, in the last decade, liquid-phase exfoliation of graphite to give
pristine graphene has been thought as a promising way to massive production of
graphene at high efficiency and low cost, in terms of the cheap and abundant
graphite source and a variety of cost-effective exfoliation techniques. Though
many exfoliation techniques are available so far, this article will highlight
the recent progress of fluid dynamics route which emerges as a promising
scalable and efficient way for graphene production in the last five years. The
emphasis is set on vortex fluidic devices and pressure- and mixer-driven fluid
dynamics, with our perspectives on the latest progress, exfoliation mechanism,
and some key issues that require further study in order to realize industrial
applications.Comment: 18 figure
Contract Enforcement and Family Control of Business: Evidence from China
Family control of business is prevalent in developing economies, and one of the leading theories suggests that it is a response to weak contract enforcement in such economies. In this paper, we investigate the impacts of contract enforcement on the degree of family control of business using a sample of China's private enterprises. It is found that weaker contract enforcement is associated with the higher degree of family control of business. Our results are robust to the control for omitted variables and reserve causality issues, to the adjustment for the sample attrition bias, to the use of a sub-sample, and to the inclusion of other explanations for the family control of business.Family Control of Business, Contract Enforcement, China's Private Enterprises
Pure Exporter: Theory and Evidence
This paper provides the first evidence about pure exporters (i.e., firms exporting all of their output to the foreign market) -- a phenomenon overlooked and cannot be explained in the existing literature. It then offers a generalized model of Melitz (2003) for examining the existence and behavior of pure exporters. In particular, pure exporters arise when the export market is sufficiently large -- a situation more likely to hold in developing countries as opposed to large developed countries; and their productivity levels are above those of non-exporters, but below those of firms having both domestic sales and export. These theoretical predictions are borne out in a data of Chinese manufacturing firms for the period of 1998-2005.Pure Exporter, Firm Heterogeneity, Exporting Behavior
A Convex Formulation for Spectral Shrunk Clustering
Spectral clustering is a fundamental technique in the field of data mining
and information processing. Most existing spectral clustering algorithms
integrate dimensionality reduction into the clustering process assisted by
manifold learning in the original space. However, the manifold in
reduced-dimensional subspace is likely to exhibit altered properties in
contrast with the original space. Thus, applying manifold information obtained
from the original space to the clustering process in a low-dimensional subspace
is prone to inferior performance. Aiming to address this issue, we propose a
novel convex algorithm that mines the manifold structure in the low-dimensional
subspace. In addition, our unified learning process makes the manifold learning
particularly tailored for the clustering. Compared with other related methods,
the proposed algorithm results in more structured clustering result. To
validate the efficacy of the proposed algorithm, we perform extensive
experiments on several benchmark datasets in comparison with some
state-of-the-art clustering approaches. The experimental results demonstrate
that the proposed algorithm has quite promising clustering performance.Comment: AAAI201
Quantum oscillations and three-dimensional quantum Hall effect in ZrTe
Recent experiments have reported a lot of spectacular transport properties in
topological materials, such as quantum oscillations and three-dimensional (3D)
quantum Hall effect (QHE) in ZrTe. In this paper, by using a strong
topological insulator model to describe ZrTe, we study the magnetotransport
property of the 3D system. With fixed carrier density, we find that there
exists a deferring effect in the chemical potential, which favors
distinguishing the saddle points of the inverted LLs. On the other hand, with
fixed chemical potential, the features of 3D QHE are demonstrated and we
attribute the underlying mechanisms to the interplay between Dirac fermions,
magnetic field and impurity scatterings.Comment: 11 pages, 5 figure
The Effectiveness of a Hybrid Cybersecurity Summer Camp for Teachers
Cybersecurity teacher education plays a vital role in narrowing the gap in the need for cybersecurity professionals in the workforce. In this paper, the authors examined the effectiveness of a hybrid cybersecurity summer camp for secondary education in-service teachers. The pre- and post-camp quizzes showed significant statistical difference, t(17) = -8.42, p \u3c .001, with a large effect size of 2.24. Focus group interviews with the teacher participants further suggested that the hybrid modality is not only viable but also a preferred format welcomed by the teachers
Learning-by-Teaching in CS Education: A Systematic Review
To investigate the strategies and approaches in teaching Computer Science (CS), we searched the literature review in CS education in the past ten years. The reviews show that learning-by-teaching with the use of technologies is helpful for improving student learning. To further investigate the strategies that are applied to learning-by-teaching, three categories are identified: peer tutoring, game-based flipped classroom, and teachable agents. In each category, we further searched and investigated prior studies. The results reveal the effectiveness and challenges of each strategy and provide insights for future studies
- …