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排序方式: 共有909条查询结果,搜索用时 171 毫秒
901.
Janet L. DeGrazia Jacquelyn F. Sullivan Lawrence E. Carlson Denise W. Carlson 《工程教育杂志》2001,90(4):557-563
Supported by the National Science Foundation, the GK‐12 Fellows program at the University of Colorado at Boulder explores innovative ways for engineering graduate students to use engineering as the vehicle to provide K‐12 classroom instruction and hands‐on experiences that integrate physical sciences, mathematics, engineering and technology. Engineering “Fellows” fill a crucial gap in the two‐way exchange of content and pedagogy between the College of Engineering and Applied Science and the K‐12 community of learners. The active presence of real world, engineering role models in K‐12 classrooms improves the quality of math and science content, and introduces engineering to teachers and young students as a potential career path. Working through the University's graduate program legitimizes K‐12 outreach as a valid, and satisfying, academic endeavor for graduate students. 相似文献
902.
This paper gives a general way to take into account, by an appropriate design of the controller, any discrepancy which can occur between the actual inputs of a process and the desired outputs of its controller. This yields to the so-called conditioned control algorithms.The conditioning technique is described for multiple-input-multiple-output nonlinear controllers. Application to complex control structures is explained.The notion of a self-conditioned controller is defined in order to simplify the implementation of the conditioning technique. Some considerations about the stability of conditioned systems are given. The automatic initialization of any control algorithm is given as an application of the method. It shows that bumpless transfer can be achieved. 相似文献
903.
Lin Li Rebecca E. Sengpiel Denise L. Pascual Lenore P. Tedesco Jeffrey S. Wilson Emmanuel Soyeux 《International journal of remote sensing》2013,34(15):4147-4162
This research estimates phytoplankton pigment concentrations (chlorophyll‐a (chl‐a) and phycocyanin (PC)) from hyperspectral Airborne Imaging Spectrometer for Applications (AISA) imagery. AISA images were acquired for a meso‐eutrophic reservoir in Central Indiana, USA. Concurrent with the airborne image acquisition, in situ water samples and reflectances were collected. The water samples were subsequently analysed for pigment concentrations, and in situ measured reflectance spectra were used for calibrating the AISA images. Spectral indices, derived from the AISA reflectance spectra, were regressed against the measured pigment concentrations to derive algorithms for estimating chl‐a and PC. The relationship between the pigment concentrations and the spectral indices were analysed and evaluated. The results indicate that the highest correlation occurred between chl‐a and a near‐infrared to red ratio (coefficient of determination R 2?=?0.78) and between PC and the reflectance trough at 628 nm (R 2?=?0.80). The relationship between PC and the reflectance at 628 nm provides an approach to the estimation of cyanobacteria concentration from hyperspectral imagery, which facilitates water‐quality authorities or management agencies in making well‐informed management decisions. 相似文献
904.
Jose Manuel Sojo-Gordillo Carolina Duque Sierra Gerard Gadea Diez Jaime Segura-Ruiz Valentina Bonino Marc Nuñez Eroles Juan Carlos Gonzalez-Rosillo Denise Estrada-Wiese Marc Salleras Luis Fonseca Alex Morata Albert Tarancón 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(17):2206399
Semiconductor nanowires have demonstrated fascinating properties with applications in a wide range of fields, including energy and information technologies. Particularly, increasing attention has focused on SiGe nanowires for applications in a thermoelectric generation. In this work, a bottom-up vapour-liquid-solid chemical vapour Deposition methodology is employed to integrate heavily boron-doped SiGe nanowires on thermoelectric generators. Thermoelectrical properties –, i.e., electrical and thermal conductivities and Seebeck coefficient – of grown nanowires are fully characterized at temperatures ranging from 300 to 600 K, allowing the complete determination of the Figure-of-merit, zT, with obtained values of 0.4 at 600 K for optimally doped nanowires. A correlation between doping level, thermoelectric performance, and elemental distribution is established employing advanced elemental mapping (synchrotron-based nano-X-ray fluorescence). Moreover, the operation of p-doped SiGe NWs integrated into silicon micromachined thermoelectrical generators is shown over standalone and series- and parallel-connected arrays. Maximum open circuit voltage of 13.8 mV and power output as high as 15.6 µW cm−2 are reached in series and parallel configurations, respectively, operating upon thermal gradients generated with hot sources at 200 °C and air flows of 1.5 m s−1. These results pave the way for direct application of SiGe nanowire-based micro-thermoelectric generators in the field of the Internet of Things. 相似文献
905.
Laura de Andrade Souza Denise Ramos Moreira Nágila Maria Pontes Silva Ricardo Martin Edmund Maier Paulo Roberto Campos Flexa Ribeiro Filho Francisco Murilo Tavares Luna Cesar Liberato Petzhold 《Journal of the American Oil Chemists' Society》2023,100(2):175-184
Vegetable oils are very promising alternatives to fossil lubricants due to their abundance, low cost, excellent performance, and environmental friendliness. Due to its multifunctional structure, castor oil is an excellent precursor in the synthesis of new biolubricants. However, it showed poor thermal-oxidative stability and a higher pour point. This study used castor oil fatty acids prepared by transesterification (EHRO), epoxidation (TEPO), and oxirane ring opening with the aromatic amines aniline (ANIL) and p-anisidine (ANIS). The chemical structure of these oils was verified by 1H and 13C NMR analysis, and mass spectrometry. Measurements show that the presence of an aromatic amine increases the viscosity resulting in 172 (ANIL) and 199 (ANIS) cSt at 40°C, but reduces viscosity index to 16 and 1, respectively. In addition, the amine groups can scavenge radicals increasing their thermal and oxidative stability. These products do not oxidize copper, and tribological analysis reveals that ANIS has the lowest torque with wear equivalent to commercial mineral lubricant NH-140. 相似文献
906.
Mattia Franceschi Luca Pezzato Claudio Gennari Denise Hanoz Rachele Bertolini Alberto Fabrizi Marina Polyakova Katya Brunelli Franco Bonollo Manuele Dabalà 《国际钢铁研究》2023,94(9):2200821
The microstructural evolution of a novel high-silicon carbide-free bainitic steel at different austempering temperatures is investigated. The microstructure is evaluated by means of optical and electron microscopy, X-ray diffraction, microhardness, and nanohardness. Results show a variation in the amount of stabilized retained austenite changing the temperature of the isothermal treatment. In particular, it is observed an increase in the retained austenite volume fraction increasing the temperature up to 350 °C, while further increase leads to a reduction. Moreover, increasing the isothermal holding temperature from 250 °C, through 300, 350, and 370 °C, a progressive bainite coarsening and an increase in the amount of stabilized carbon-enriched retained austenite are observed. Tensile tests reveal an excellent combination of mechanical properties: mechanical strength in the range 1276–1988 MPa and total elongation 0.18–0.44. 相似文献
907.
908.
Ana Teresa Silva Dr. Isabel S. Oliveira Joana Gomes Dr. Luísa Aguiar Dr. Diana Fontinha Dr. Denise Duarte Dr. Fátima Nogueira Miguel Prudêncio Prof. Eduardo F. Marques Dr. Cátia Teixeira Prof. Ricardo Ferraz Prof. Paula Gomes 《ChemMedChem》2022,17(5):e202100650
Inspired by previous disclosure of room-temperature ionic liquids derived from primaquine and cinnamic acids, which displayed slightly enhanced blood-stage activity compared to the parent drug, we have now combined this emblematic antimalarial with natural fatty acids. This affords surface-active ionic liquids whose liver-stage antiplasmodial activity is either retained or slightly enhanced, while revealing blood-stage antiplasmodial activity at least one order of magnitude higher than that of the parent compound. These findings open new perspectives towards the cost-effective recycling of classical drugs that are either shelved or in decline, and which is not limited to antimalarial agents. 相似文献
909.
Chuy Gabriela Pereira Muraro Pâmela Cristine Ladwig Viana Altevir Rossato Pavoski Giovani Espinosa Denise Crocce Romano Vizzotto Bruno Stefanello da Silva William Leonardo 《Journal of Inorganic and Organometallic Polymers and Materials》2022,32(4):1213-1222
Journal of Inorganic and Organometallic Polymers and Materials - Antimicrobial resistance represents a serious concern to public health, being responsible for hospital infections, affecting mainly... 相似文献