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Open access

Gong Chen

Rationale of Self-defense Education in American Schools

The purpose of this article is to examine the critical roles and benefits of self-defense and self-defense education for students in American middle and high schools. The article will analyze crime trends and the self-defense education status in America, and discuss rationale of self-defense and self-defense education from both the theoretical and practical perspectives. This article tried to provide a comprehensive view on theories and practice of self-defense education for American school students. Self-defense instructors can consider the ideas presented herein to persuade their school administrators to initiate or strengthen their self-defense education programs, convince parents of the need, and obtain their support and cooperation. Ideas we presented can also be useful in motivating students to learn self-defense while helping instructors develop a comprehensive understanding of self-defense education.

Open access

P Chen

Abstract

Cigarette-burning and the smoke-formation processes and smoke composition are important topics for understanding cigarette performance. This paper proposes the molecular formulas representing the active components of bright, burley, and Oriental tobaccos and a basic chemistry model of the cigarette burning processes. Previous knowledge of the cigarette burning processes and smoke formation helped to establish parameters in deriving the basic chemistry equations. The proposed chemistry provides a brief view of the mechanisms of the cigarette burning during puffing and interpuff smoldering, and can be used to interpret and predict the smoke composition for cigarettes made from bright, burley, and Oriental tobaccos. Based on the proposed chemistry, the effect of ventilation on smoke component deliveries is discussed and the reaction heat of the puffing process is estimated.

Open access

P Chen

Abstract

A mathematical model for a smoldering cigarette has been proposed. In the analysis of the cigarette combustion and pyrolysis processes, a receding burning front is defined, which has a constant temperature (~450 °C) and divides the cigarette into two zones, the burning zone and the pyrolysis zone. The char combustion processes in the burning zone and the pyrolysis of virgin tobacco and evaporation of water in the pyrolysis zone are included in the model. The hot gases flow from the burning zone, are assumed to go out as sidestream smoke during smoldering. The internal heat transport is characterized by effective thermal conductivities in each zone. Thermal conduction of cigarette paper and convective and radiative heat transfer at the outer surface were also considered. The governing partial differential equations were solved using an integral method. Model predictions of smoldering speed as well as temperature and density profiles in the pyrolysis zone for different kinds of cigarettes were found to agree with the experimental data. The model also predicts the coal length and the maximum coal temperatures during smoldering conditions. The model provides a relatively fast and efficient way to simulate the cigarette burning processes. It offers a practical tool for exploring important parameters for cigarette smoldering processes, such as tobacco components, properties of cigarette paper, and heat generation in the burning zone and its dependence on the mass burn rate.

Open access

Gong Chen

Self-Defense Competency of American College Students in Self-Defense Class in Physical Education Program

The purpose of this project was to investigate physical self-defense competency of American college students in laboratory situation. The physical self-defense competency was examined through five categories of physical self-defense abilities that occurred in real life situation, including abilities of dealing with throws, standing holds, floor holds, knife attacks, and gun attacks. The results indicated that female and male students demonstrated high level of self-defense competency on dealing with throws, standing holds, and floor holds. The results also indicated effective strategies and skills for college men and on women dealing with knife attacks.

Open access

Chaomei Chen

Abstract

Purpose

We present a systematic review of the literature concerning major aspects of science mapping to serve two primary purposes: First, to demonstrate the use of a science mapping approach to perform the review so that researchers may apply the procedure to the review of a scientific domain of their own interest, and second, to identify major areas of research activities concerning science mapping, intellectual milestones in the development of key specialties, evolutionary stages of major specialties involved, and the dynamics of transitions from one specialty to another.

Design/methodology/approach

We first introduce a theoretical framework of the evolution of a scientific specialty. Then we demonstrate a generic search strategy that can be used to construct a representative dataset of bibliographic records of a domain of research. Next, progressively synthesized co-citation networks are constructed and visualized to aid visual analytic studies of the domain’s structural and dynamic patterns and trends. Finally, trajectories of citations made by particular types of authors and articles are presented to illustrate the predictive potential of the analytic approach.

Findings

The evolution of the science mapping research involves the development of a number of interrelated specialties. Four major specialties are discussed in detail in terms of four evolutionary stages: conceptualization, tool construction, application, and codification. Underlying connections between major specialties are also explored. The predictive analysis demonstrates citations trajectories of potentially transformative contributions.

Research limitations

The systematic review is primarily guided by citation patterns in the dataset retrieved from the literature. The scope of the data is limited by the source of the retrieval, i.e. the Web of Science, and the composite query used. An iterative query refinement is possible if one would like to improve the data quality, although the current approach serves our purpose adequately. More in-depth analyses of each specialty would be more revealing by incorporating additional methods such as citation context analysis and studies of other aspects of scholarly publications.

Practical implications

The underlying analytic process of science mapping serves many practical needs, notably bibliometric mapping, knowledge domain visualization, and visualization of scientific literature. In order to master such a complex process of science mapping, researchers often need to develop a diverse set of skills and knowledge that may span multiple disciplines. The approach demonstrated in this article provides a generic method for conducting a systematic review.

Originality/value

Incorporating the evolutionary stages of a specialty into the visual analytic study of a research domain is innovative. It provides a systematic methodology for researchers to achieve a good understanding of how scientific fields evolve, to recognize potentially insightful patterns from visually encoded signs, and to synthesize various information so as to capture the state of the art of the domain.

Open access

Junping Chen and Jiexian Wang

Reduced-Dynamic Precise Orbit Determination for Low Earth Orbiters Based on Helmert Transformation

A model based on Helmert transformation is presented in reduced-dynamic Precise Orbit Determination(POD). As an implementation, a reduced-dynamic POD approach was developed. The approach includes two steps: firstly, kinematic POD and then reduced-dynamic POD. Based on the approach, a set of programs were developed. POD of CHAMP and GRACE was then carried out. Kinematic and reduced-dynamic POD for CHAMP and GRACE satellite over 2 weeks time show that reduced-dynamic orbits of CHAMP have a mean 3D RMS of 0.26 m compared to PSO orbit of GFZ, and the mean 3D RMS of GRACE-A has the same value compared to GNV1B orbit of JPL. The 3D RMS is reduced by up to 40% compared to kinematic solutions.

Open access

Sarah Chen and Amandio Vieira

A meta-analysis of medicinal plants to assess the evidence for toxicity

Toxicity of phytochemicals, plant-based extracts and dietary supplements, and medicinal plants in general, is of medical importance and must be considered in phytotherapy and other plant uses. We show in this report how general database analyses can provide a quantitative assessment of research and evidence related to toxicity of medicinal plants or specific phytochemicals. As examples, several medicinal plants are analyzed for their relation to nephrotoxicity and hepatotoxicity. The results of analyses in different databases are similar, and reveal the two best-established toxic effects among the group of plants that were examined: nephrotoxicity of Aristolochia fangchi and hepatotoxicity of Larrea tridentata.

Open access

Vasilis Pagonis and Reuven Chen

Simulation of OSL Pulse-Annealing at Different Heating Rates: Conclusions Concerning the Evaluated Trapping Parameters and Lifetimes

Pulse annealing has been the subject of several studies in recent years. In its basic form, it consists of relatively short-time optically stimulated luminescence (OSL) measurements of a given sample after annealing at successively higher temperatures in, say, 10°C increments. The result is a decreasing function with a maximum OSL at low temperatures and gradually decreasing to zero at high temperature. Another presentation is that of the percentage OSL signal lost per annealing phase, associated with minus the derivative of the former curve, which yields a thermoluminescence (TL)-like peak. When the heating is performed at different heating rates, the TL various heating rates (VHR) method can be utilized to evaluate the trapping parameters. Further research yielded more complex pulse-annealing results in quartz, explained to be associated with the hole reservoir. In the present work, we simulate numerically the effect, following the experimental steps, in the simpler form when no reservoir is involved, and in the more complex case where the reservoir plays an important role. The shapes of the reduction-rate curves resemble the experimental ones. The activation energies found by the VHR method are very close to the inserted ones when the retrapping probability is small, and deviate from them when retrapping is strong. The theoretical reasons for this deviation are discussed.

Open access

Liu Liu and Gong Chen

Exercise Intensity, Perception of Benefits, and Preferences on Taichi and Chigong Exercises of American College Students

The purposes of this study was to investigate the exercise intensity through heart rate and sweat rate during taichi and chigong workout, student perception on the benefits of different taichi and chigong exercises, and preferred taichi and chigong exercises of American college students. The results indicated that: 1) Taichi and chigong exercises increased heart rate of college students to light intensity level based on ACSM criteria even though the main purpose of taichi and chigong exercise focuses on inner health instead generating high level heart rate. 2) More than 60% students had heavy sweat during practice of most taichi and chigong exercise except Crane style chigong. 3) Most students felt that taichi and chigong exercises are useful for their external fitness, inner health, stress and anxiety reduction, and relaxation. These exercises include simplified Crane Chigong, simplified Taichi Chigong, Standard 24 form Taichi, Stationary Taichi, taichi and chigong combination, and Free Style taichi. 4) Men showed high interest on 24 form taichi and individual work out on this form, and doing taichi/chigong in the gym with music. Women demonstrated high interest on the combination the three key taichi/chigong elements, 24 form taichi, and working out with music and following the instructor. It is expected that the results can be used as a reference for taichi and chigong instructors for designing and teaching taichi classes for the best of student interests.