18,901 research outputs found
The influence of different metallic counterparts on the tribological performance of nc-CrC/GLC in seawater
No full textIn order to discuss the wear situation of nc-CrC/GLC film sliding against different counterparts in seawater, the nc-CrC/GLC film was fabricated by unbalance magnetron sputtering technique on silicon wafer and 304L stainless steel. The SEM, Raman, TEM were used to measure the morphologies, components and microstructures of nc-CrC/GLC film. The nanoindentation test was used to acquire the hardness and elastic modulus of nc-CrC/GLC film. The tribological performances of nc-CrC/GLC film sliding against different metallic counterparts including Al, Ti, H62, GCr15 in seawater were comparatively investigated by a reciprocating tribo-meter and the tribological mechanisms were highly analyzed via Hertz contact theory. The tribo-chemical products, worn surfaces of nc-CrC/GLC film and metallic counterpart were observed by scanning electron microscope (SEM). The results showed that the hardness and elastic modulus of nc-CrC/GLC film were about 14.09 +/- 1.32 and 169.16 +/- 1339 GPa, respectively The friction coefficients of nc-CrC/GLC film sliding against H62, GCr15, Ti, Al counterparts were about 0.18, 0.135, 0.085 and 0.06, respectively. Meanwhile, it was found that the wear rate of nc-CrC/GLC-Al was the lowest value of 0.23 x 10(-7) mm(3)/Nm, while the wear rate of nc-CrC/GLC-H62 was the highest value of 1.79 x 10(-7) mm(3)/Nm. The tribological performances of nc-CrC/GLC film would be improved by chosen an appropriate counterpart. The nc-CrC/GLC-Al showed low friction and wear in mixed lubrication, and the wear mechanism was regarded as adhesive and corrosion wear. Whereas the nc-CrC/GLC-Ti and nc-CrC/GLC-GCr15 were known as corrosion and three-body abrasive wear, the nc-CrC/GLC-H62 showed a hybrid mechanism of adhesive, abrasive and corrosion wear. (C) 2017 Elsevier B.V. All rights reserved
The construction of Karen Karnak: The multi-author-function
No full textThis thesis is situated within the comparatively recent developments of Web 2.0 and the emergence of interactive WikiMedia, and explores the mode of authorship within a Read/Write culture compared to that of a Read/Only tradition. The hypothesis of this study is that the role of the audience has become merged with the author, and as such, represents new functions and attributes, distinct from a more conventional concept of authorship, in which the roles of audience and author are more separate. Read/Write and participatory culture, as defined by this study, is focused on collaboration, and includes the influences of D.I.Y. culture, Open-Source practices and the production of text by multiple authors. Multi-authorship presents a re-thinking of several concepts which support the notion of the individual author, since the focus of multi-authorship is not on attribution and ownership of a finished text, but on the continued malleability of a text. Modes of multi-authorship, demonstrated in the use of the pseudonyms Alan Smithee and Karen Eliot, represent declarative authors whose names signify multiple origins, whilst concurrently indicating a distinct body of work. The function of these names form an important context to this study, since primary research involves the construction of an experimental mode of multi-authorship utilising WikiMedia technology and the interaction of thirty nine participants, who are invited to create a body of work under the collective pseudonym Karen Karnak. The data generated by this experiment is analysed using aspects of Michel Foucault's author-function to identify and determine power structures inherent in the WikiMedia context. The interplay of power structures, including concepts such as identity, ownership and the body of work, affect the resulting mode of authorship and contribute to the construction of Karen Karnak, suggesting further areas of research into the emerging multi-author
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Um Sistema para o projeto e fabricação de peças mecânicas a distância via internet aderente à norma ISO 14649 (STEP-NC)
Full text linkTese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia MecânicaCom o rápido avanço da tecnologia da informação associada à tecnologia da fabricação, os ambientes de manufatura mudaram significativamente nas últimas décadas. A usinagem de alta velocidade, usinagem de ultra-precisão e usinagem de múltiplos eixos tem melhorado a produtividade e a qualidade da manufatura. Além disso, a tecnologia da internet introduziu a e-manufatura (isto é, projetado por qualquer um em qualquer lugar, fabricado por qualquer um em qualquer lugar). A chave para o sucesso da e-manufatura consiste em um fluxo de dados compatíveis e sem brechas na cadeia CAD-CAPP-CAM-CNC. Apesar do avanço nas tecnologias de manufatura, a linguagem que as máquinas de comando numérico utilizam nos dias de hoje (código G # norma ISO 6983) ainda baseia-se nas movimentações da extremidade das ferramentas e no status da máquina, fazendo com que muitas informações acerca do produto sejam perdidas, tornando difícil ou impossível o compartilhamento de tais informações em diferentes áreas da empresa. O padrão ISO 14649 (STEP-NC) fornece um modelo de informações de alto nível referentes ao produto, como por exemplo o uso de features para a modelagem de peças e operações de fabricação, e este padrão tem sido apontado como uma ferramenta adequada para superar os problemas acima mencionados. Assim, para um mercado onde é bastante comum a elevada variabilidade das peças sendo produzidas, a alteração nas features que compõem a peça é mais rápida e fácil do que a alteração do código G para a usinagem da peça, e desta forma capacita-se as empresas a responderem mais rapidamente à mudança no projeto das peças, além de contribuir para acelerar a tomada de decisões referentes à fabricação das peças. Uma outra vantagem do uso de STEP-NC é que a sua estruturação proporciona que organizações de manufatura venham a compartilhar informações de maneira transparente via Internet. Tendo em vista o contexto acima, no presente trabalho foi desenvolvido um protótipo de um sistema computacional CAD/CAPP/CAM voltado à manufatura remota de peças mecânicas de característica prismática utilizando a Internet como meio de comunicação, sendo completamente aderente ao padrão ISO 14649. No sistema desenvolvido foram disponibilizadas inúmeras features para o usuário remoto, incluindo não apenas superfícies com características prismáticas, mas também elementos curvos como fundos abaulados de cavidades. Um dos módulos do sistema verifica se a peça criada pelo usuário é válida do ponto de vista de fabricabilidade com as ferramentas disponíveis. Além disso, o sistema identifica se a peça pode ser fabricada em uma máquina de comando numérico de três eixos, e no caso de impossibilidade o sistema informa o usuário o que causou a não-fabricabilidade. Finalmente, o sistema gera automaticamente o arquivo físico no formato STEP (padrão ISO 10303 parte 21), o qual é disponibilizado para o usuário via Internet, podendo ele efetuar uma simulação gráfica dos movimentos das ferramentas usinando a peça, tendo o arquivo físico como entrada. Até o momento não foi desenvolvido nenhum sistema computacional que disponibilize tal arquivo gratuitamente na Internet, e consequentemente o sistema desenvolvido neste trabalho contribui para uma maior disseminação do padrão STEP-NC, além do fato que o arquivo gerado poderá ser utilizado em máquinas CNC reais compatíveis com o formato STEP parte 21.With the rapid advancement of information technology associated with manufacturing technology, manufacturing environments have changed significantly in recent decades. High speed machining, ultra-precision machining, and multi-axis machining have improved manufacturing productivity and quality. In addition, Internet technology has introduced e-manufacturing (i.e., designed by anyone anywhere, manufactured by anyone anywhere). The key to the success of e-manufacturing consists of compatible data stream with no gaps in the CAD-CAPP-CAM-CNC chain. Despite advances in manufacturing technologies, the language that are used by numerical control machines today (i.e. G-code - ISO 6983 standard) is still based on the movements of the end of the tools and on the machine status, causing the loss of much information about the product, making it difficult or impossible to share such information in different areas of the company. The ISO 14649 (STEP-NC) standard provides a model of high-level information about the product, such as the use of features for the modeling parts and manufacturing operations, and this standard has been recommended as a suitable tool to overcome the aforementioned problems. Thus, for a market where it is quite common the high variability of parts being produced, the change in features that compose the part is faster and easier than changing the G code for machining the part, and thus companies are enabled to respond more quickly to the change in part design, besides helping to accelerate decision-making related to the manufacture of parts. Another advantage of using STEP-NC is that its structure enables manufacturing organizations to share information seamlessly via the Internet. Given the above context, in the present research work a prototype CAD/CAPP/CAM computer system was developed for the remote manufacture of mechanical prismatic mechanical parts using the Internet as a means of communication, completely compliant with the ISO 14649 standard. In the developed system many features are provided to the remote user, including not only surfaces with prismatic features, but also curved elements like general cavities. One of the modules of the system verifies whether the part created by the user is valid from the standpoint of manufacturability with the tools available. In addition, the system identifies whether the part can be manufactured in a numerical control machine with three axes, and if that is not feasible, the system informs the user the cause of non-manufacturability. Finally, the system generates automatically the physical STEP file (ISO 10303 Part 21), which is provided to the user via the Internet, and he can perform a graphic simulation of the movement of the tools machining the part, having the physical file as input. So far no computer system was developed that provides such a file for free on the Internet, and therefore the system developed in this work contributes to a further spread of the STEP-NC standard, plus the fact that the generated file can be used in real CNC machines compatible with the STEP part 21 format
Formation of a dipolar adduct in the reaction of arylchlorocarbenes with diethyl maleate
No full textPT: J; CR: COX DP, 1983, TETRAHEDRON LETT, V24, P5313 DEHMLOW EV, 1984, ANGEW CHEM INT EDIT, V23, P706 DOYLE MP, 1984, TETRAHEDRON LETT, V25, P901 GOULD IR, 1985, TETRAHEDRON, V41, P1587 LAMBERT JB, 1983, TETRAHEDRON LETT, V24, P3799 LIU MTH, 1977, TETRAHEDRON LETT, P3139 LIU MTH, 1985, J CHEM SOC CHEM COMM, P982 LIU MTH, 1985, TETRAHEDRON LETT, V26, P3071 LIU MTH, 1986, J PHYS CHEM-US, V90, P75 MORIARITY RM, 1985, J AM CHEM SOC, V107, P1357 MOSS RA, 1979, J AM CHEM SOC, V101, P4736 MOSS RA, 1980, ACCOUNTS CHEM RES, V13, P58 MOSS RA, 1983, TETRAHEDRON LETT, V24, P2719 MOSS RA, 1985, REACTIVE INTERMEDIAT, V3 YANG NC, 1968, J AM CHEM SOC, V90, P5654; NR: 15; TC: 7; J9: TETRAHEDRON LETT; PG: 4; GA: D9916Source type: Electronic(1
SV40 small t antigen can repress AP-1 transcriptional activity by targeting transcriptional coactivator p300
No full textSV40 small t antigen can repress gene expression by targeting transcriptional coactivator p300
No full textData for: Winter Equatorial Warming in Martian Upper Atmosphere from MAVEN densities
No full textDataset for the publication "Winter Equatorial Warming in Martian Upper Atmosphere from MAVEN densities" by Liu et al.
The dataset is the simulation results of Laboratoire de Météorologie Dynamique‐Mars General Circulation Model (LMD-MGCM) under MY25 dust scenario, which includes Martian month 10, 11, and 12. The results are all .nc files that can be read and used by multiple-software such as NOAA ferret. Each of .nc file are organized with lat-lon-alt-time, which includes density (kg/m^3), temperature (K), zonal winds U (m/s), and meridional winds V (m/s) from Mars surface up to 260 km.
The dataset includes three folders with the simulation results .nc. , the control def files for running the simulation as well as the average densities from observations.
Folder01: simulation results
The .nc files are named like diagfiXX_A.nc.
XX is the Martian month;
_A means the altitude have been normalized to km.
The 10ls1.txt are for the longitudinal average of the LMD-MGCM density for month 10 abstracted form diagfi10_A. nc by Ferret order “list”.
# 12 martian months (=30 deg Ls) of unequal length (excentric orbit)
Length of sols/ month
/61/ #1
/66/ #2
/66/ #3
/65/ #4
/60/ #5
/54/ #6
/50/ #7
/46/ #8
/47/ #9
/47/ #10
/51/ #11
/56/ #12
Folder02: def files
def files for the LMD-MGCM simulation
Folder03: averaged densities
Averaged densities from NGIMS and ACC.
This work made use of the High Performance Computing Resource in the Core Facility for Advanced Research Computing at Shanghai Astronomical Observatory
Carrier transport properties of the (n)nc-Si : H/(p)c-Si heterojunction
No full textPhosphor-doped nano-crystalline silicon ((n))nc-Si:H) films are successfully grown on the p-type (100) oriented crystal silicon ((p) c-Si) substrate by conventional plasma-enhanced chemical vapor deposition method. The films are obtained using high H-2 diluted SiH4 as a reaction gas source and using PH3 as the doping gas source of phosphor atoms. Futhermore, the heterojunction diodes are also fabricated by using (n)nc-Si:H films and (p)c-Si substrate. I-V properties are investigated in the temperature range of 230-420K. The experimental results domenstrate that (n)nc-Si:H/(p) c-Si heterojunction is a typical abrupt heterojunction having good rectifing and temperature properties. Carrier transport mechanisms are tunneling - recombination model at forward bias voltages. In the range of low bias voltages ( V-F1.0 V). The present heterojunction has high reverse breakdown voltage ( > - 75 V) and low reverse current (approximate to nA)
Estimating the Potential Impact of Carbon Markets on North Carolina Forests
No full textSeveral studies have examined the theoretical aspects of determining the optimal carbon rotation. This paper explores the tradeoff between timber and net carbon sequestration in managing representative forest management types in North Carolina. Under conservative assumptions regarding the social benefits of carbon storage, optimal rotation periods are extended depending on the forest type, carbon price, interest rate, and emission penalty under consideration. Analysis shows when carbon price is low the extension of the joint timber-carbon rotation are similar among DOE, CCX, and VCS protocols; when carbon price is high, the joint rotation extends longer under DOE protocol than the other two protocols, especially in the lowland hardwood forest type. Results suggest that such joint strategies could be financially attractive. Sensitivity analysis is used to examine the effects of changes in financial parameters on landowner returns and optimal management. Under most assumptions, our findings indicate that including carbon sequestration in forest management increases returns but leads to only marginal changes in rotation length
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