691 research outputs found
Geochemical and Sm–Nd isotopic characteristics of metabasites from central Hainan Island, South China and their tectonic significance
No full textBreathing city: Mitigating air pollution through urban microclimate design
No full textIn recent years, with the deepening of the urbanization process, high-density urban development models have led to a series of climatic problems such as poor urban ventilation and air pollution. Urban morphology forms a unique microclimate in the city, which has an important impact on the diffusion and distribution of pollutants inside the urban boundary layer. Chengdu, as a large central city in the southwestern of China, has developed rapidly, with numerous sources of atmospheric pollution. At the same time, its basin topography and climatic conditions make it difficult to dilute and disperse pollutants. In this thesis, the background of Chengdu was introduced, and the severe trend of urban development and air pollution was stated at first. Secondly, further understanding of the relationship between urban morphology, urban microclimate and air pollution will be involved. And a city-scale risk assessment was conducted to define the most vulnerable areas. Thereafter, it is possible to evaluate the microclimates represented by the wind and heat environment in these areas. Then integrating pollution abatement and microclimate design into the urban design process by using a maximization approach. From the aspects of street canyon morphology, surfaces and urban trees, proposing wind-heat coupled optimization solutions to reduce air pollution. The guidelines and design method are aimed at improving the scientificity of urban design and providing a reference for the creation of sustainable and healthy cities.Architecture, Urbanism and Building Science
Revised burst model for pipeline integrity assessment
No full textThe failure of pipelines，often caused by corrosion affects the environment and
economy considerably. To prevent this, it is necessary to focus on the corrosion of the
pipelines. Burst pressure is a key factor to assess the integrity of a pipeline. There are
three ways to determine burst pressure, lab testing, evaluation criteria (based on
deterministic approach), and the Finite Element Method (FEM). The results of burst
pressure assessment using evaluation criteria are too conservative compared to the
results of an actual pipe burst experiment and FEM (Alves J L, 2003).
The objectives of this thesis are to analyze the changing trend of burst pressure of
pipelines with different defect dimensions; to compare the FEM results with those of
the evaluated criteria to indicate the conservative property; and to revise the DNV
burst model and verify its validity with actual burst experiments. The revised DNV
model predicts burst pressure more reliably that could result in better engineering
design of pipelines.Includes bibliographical references (pages 81-86)
Electron-induced carbon tetrachloride Adsorption on Ice
No full textCharge-induced adsorption is a subject of significance to environmental and biological systems. Ice surface is believed to get charged with potassium deposition. Compared to uncharged ice film, the work function of charged ice film is significantly reduced due to the formation of metastable delocalized excess surface electrons donated by potassium atoms on ice. This charging effect is found to be dependent on temperature. It is also reported that adsorption of carbon tetrachloride would occur drastically on charged ice surface while almost no adsorption was observed on uncharged ice surface at low temperature. In addition, the results strongly agree with the cosmic-ray-driven electron-induced reaction (CRE) model for ozone depletion.1 yea
Detecting code duplications in the NPM community
No full textIn the modern software development process, it has become a very mainstream practice to build software projects on top of third-party packages to simplify the development process. In this development method, it is quite common to copy existing code or files in other libraries instead of making regular calls. Although this approach can reduce the project's dependence on other libraries and make the project more streamlined, it also causes difficulties in maintenance and understanding. The ignorance of code duplication by third-party library community can even be exploited for malicious purpose, such as typo-squatting attack. This paper serves as a starting point to analyze the growing code duplication issues surrounding third-party open source packages, and what is the root cause of code duplication. In this paper, I conducted code duplication-related research based on some popular packages in the third-party open source packages community, the NPM community, by using the tokenizer tool and the code comparison tool to compute the code similarity, quantitatively analyzed the prevalence of code duplication in the NPM community, and did some related experiments based on this similarity. In the experiments, I found that code duplication is very common in NPM community: 17.1% of all the files have 1-93 similar file in other package when the threshold of similar file is set to 0.5. 29.3% of all the packages has at least one "similar package" when the threshold of similar package is set to 0.5. In all the 951 similar package pairs, 33.9% of them, 323 package pairs comes from the same domain. The ultimate goal of this paper is to promote the awareness of the commonness and the importance of code duplication in the third-party package community and the reasonable use of code duplication by developers in the project development.In the modern software development process, developers often call other people's completed code to build their own programs. There are generally two ways to do this: indirectly call other people's code through "import" or similar instructions in the program, or directly copy and paste other people's code and make slight modifications. The second method can make the program more independent and easy to use, but the code duplication problem caused by this method also has great security risks.This paper serves as a starting point to analyze the growing code duplication issues, and what is the root cause of code duplication. In this paper, I conducted code duplication-related research based on some popular code packages in the NPM community.I used some tools to compute a value to define how different codes are similar to each other, quantitatively analyzed the prevalence of code duplication in the NPM community, and did some related experiments based on this similarity. In the experiments, I found that code duplication is very common in the NPM community: 17.1% of all the files have 1-93 similar file in other package, and 29.3% of all the package have at least one "similar package", when the definition of similar files and packages are not that "strict".In all the 951 similar package pairs, 33.9% of them, 323 package pairs comes from the same domain. The ultimate goal of this paper is to promote the awareness of the commonness and the importance of code duplication in the third-party package community and the reasonable use of code duplication by developers in the project development
The Effects of Attentional Focus Instructions on Approach Jump Performance
Get PDFIntroduction: Attentional focus is a crucial factor that impacts motor learning and performance. Instructions that direct performers’ attention externally (i.e., toward the effects of movements) have been shown to enhance performance compared to those that direct attention internally (i.e., toward the body’s movements). Research has also demonstrated that novices perform better when they are instructed to focus externally on the process of skill execution versus the outcome. However, this effect has not been tested in complex jumping skills that are important in many sports.
Purpose: The aim of this study was to test the effects of internally and externally directed process and outcome focus instructions on approach jump height and approach velocity in novice participants.
Methods: Twelve individuals between the ages of 18 and 35 participated in this study. All participants completed three sessions: Familiarization, Test Session 1, and Test Session 2. Across the two test sessions, participants performed approach jumps in a baseline condition and four experimental conditions in which participants were asked to focus on specific cues. Experimental conditions were External Focus-Outcome (EFO), Internal Focus-Outcome (IFO), External Focus-Process (EFP), and Internal Focus-Process (IFP). Jump-and-reach height, estimated jump height by flight time, and approach velocity were analyzed using separate 2 (Attentional Focus: Internal, External) x 2 (Content: Outcome, Process) ANOVAs with repeated measures.
Results: Jump-and-reach height was highest in the external focus and outcome conditions (p \u3c .05). Approach velocity was faster in process vs. outcome conditions (p \u3c .001) but did not differ between internal and external focus cues. Estimated jump height by flight time was similar across all conditions. Conclusions: This study demonstrates that the advantages of external focus and process instructions for novices may extend only to certain performance variables in complex motor skills.
Practical Applications: Practitioners can use various process- and outcome-based instructions to enhance novices’ performance. External, outcome-based cues should be used to enhance overall task performance, while process-based cues can be implemented to improve specific components of technique
Analysis of Low-Carbon Logistics Transportation Method Based on the Perspective of Low-Carbon Economy
No full textThe slip modulus between cold formed steel and timber sheathing based on fastener spacing increment
Get PDFMaster of ScienceDepartment of Civil EngineeringHani G. MelhemThe combination of cold formed steel (CFS) with structural wood panels exhibits a degree of partial composite action behavior. In the current design and construction codes, CFS and wood sheathing systems are considered separate, in a non-composite manner, due to the absence of sufficient supporting experimental and research data. The problem with previous research is the lack of information to fully define the composite action between CFS and wood sheathing. The scope of this study is to check fundamental information provided in previous research. The approach adopted to solve the problem follows previous experimental procedures conducted at Kansas State University. The objective of the research is to determine the slip modulus with various fastener spacing. Additional results obtained in this study are compared to previous research results
Topological conjugacy between Schneider's continued fraction map and a shift map on
Get PDFWe prove that Schneider's continued fraction map is topologically conjugate
to a shift map defined on , and the topological conjugation
is an isometry such that
. Furthermore, for
we proved that if and only if .Comment: 4 pages, 0 figure
- …
