1,721,212 research outputs found
인간 상지의 임피던스 특성 및 모델
No full text학위논문(석사) - 한국과학기술원 : 기계공학전공, 2011.2, [ vii, 128 p. ]When the hand is displaced from the equilibrium posture by an external disturbance, a force is generated to restore the original position and there is ample evidence that humans are able to control the endpoint impedance of their arms in response to active destabilizing force fields. Goal of this thesis is to extract the impedance information of human arm when the arm is in the particular posture and while moving on a particular trajectory. In this work two models of the arm, Joint Space Model and Muscle Space Model, are considered while major emphasize is given to Muscle Space Model. The musculoskeletal model describes planar movements of the upper arm and forearm, which are moved by eight lumped muscles with nonlinear dynamics. A non-linear Hunt-Crossley model is considered for muscles model which is the function of the velocity of the shortening or lengthening, muscle length at that instance and also on the viscoelastic parameters of the corresponding muscle. End-point impedance is estimated by simulating a given model, by transforming a muscle force to joint torque and then to endpoint impedance, which is generated due to a particular movement or while maintaining a particular arm posture. The dynamics at the endpoint level are estimated so that a comparison can be made with the experiments. The resulted impedance parameter helps to design the control of robots and human machine interface.한국과학기술원 : 기계공학전공
Efficient mercury sequestration from wastewaters using palm kernel and coconut shell derived biochars
No full textElevated mercury (Hg) concentrations in water bodies caused by illegal artisanal gold mining in Ghana is a serious health concern given the toxicity of Hg. As an ecofriendly cost-effective solution for removing Hg from these water bodies, we synthesized biochars using palm kernel (PB) and coconut shells (CB), which are dominant biomass wastes in Ghana. The biochars were sulfurized (SPB, SCB) and fabricated into polysulfone-based beads for Hg(II) sorption. The Hg(II) concentration, contact time, sorbent mass, and solution pH were investigated and were found to be influential on the sorption of Hg(II) from aqueous solution. The sulfurized biochars showed a faster Hg(II) removal (within 1h) compared to the pristine biochars. Sorption tests conducted using natural riverine water samples confirmed the potential use of the biochars, with SPB and SCB showing higher efficiencies than pristine PB and CB. The fabricated beads exhibited 70–90% efficiency in Hg(II) removal from 1.0 mg L−1 Hg solution and the sorption capacity was below 0.1 mg g−1, which we attribute to the mass of biochar used for the beads. The Hg(II) sorption mechanisms of PB and CB from spectroscopic analyses suggest that the biochars synthesized in this study can be used to treat Hg polluted waters and suitable for large-scale applications in natural water bodies.11Yscopu
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Issue of Accumulation and Redistribution of Oil and Gas Rental Income in the Context of Exhaustible Natural Resources in Arctic Zone of Russian Federation
No full textThe significant resource potential of the Arctic has attracted the attention of its adjacent countries and extra-regional states. The mineral and raw material base of the Arctic Zone of the Russian Federation (AZRF) comprises a wide range of minerals. However, due to its hydrocarbon reserves, the Arctic is considered to be the most important geopolitical and geo-economic macro-region for Russia. A significant portion of the Arctic hydrocarbons (about 19%) is concentrated in the territory of Russia’s shelf. The extraction of Arctic marine oil and gas resources and ensuring the sustainability of the Russian energy complex depend significantly on the level of Arctic development. Thus, the pace and quality of the development of AZRF are strategically important to ensure the national interests of the country. It has been proven that the implementation of the state program for AZRF development and strategic plans of the largest companies operating in the region consolidate the raw material nature of AZRF development. Rent becomes the main form of income. This article addresses the main directions of the region’s development and the factors that prevent a high level of industrialization, which increase attention to the withdrawal and redistribution of rental income. The article considers the Russian and foreign experiences of withdrawal and redistribution of oil and gas rental income, and analyzes the level of socio-economic development of AZRF. The authors suggest a methodology for assessing the impact of a country’s area and population size on the ability to achieve a high income due to hydrocarbons. The authors also explain the principles of rental income redistribution in the region as a basis for improving the level of AZRF’s socio-economic development and as a condition for transition from the “colonial model” of development to the “sustainable development” model. The study results can be used to elaborate a mechanism for rental income redistribution in AZRF and state programs for the region’s development
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