Efficiency of different types of ED-tether thrusters

The efficiencies of electrodynamic-tether (EDT) thrusters made of single bare tethers with different types of cross sections, several parallel bare tethers, or a fully insulated tether with a three-dimensional passive end-collector, are discussed. Current collection, mass, and ohmic resistance considerations are balanced against each other in discussing efficiencies. Use is made of recent results on the validity domain of orbital-motion-limited (OML) collection, the current law beyond that domain, and interference effects between parallel bare tethers; and on current adjustment to variations in electron density encountered in orbit. Comparisons between EDT thrusters and electrical thrusters in terms of the ratio of dedicated mass to the total mission impulse show EDT to be superior for mission times over 50-100 days.

Types of metaphor in civil engineering communication

La metáfora y otros mecanismos imaginativos subyacentes al pensa- miento y lenguaje humanos pueden ser utilizados en el discurso diario y especializado (Lakoff y Johnson 1980; Lakoff y Nuñez 2000). Asimismo pueden aparecer en la comunicación no verbal (Forceville y Urios-Aparisi 2009; Littlemore et al. Este volumen).Partiendo de estudios cognitivos y de la teoría de integración conceptual (Fauconnier 1997; Fauconnier y Turner 2002), este artículo examina la presencia de la metáfora en la ingeniería. Primeramente, se analiza un corpus lingüístico procedente de artículos de investigación de ingeniería civil. Los datos revelan el uso de la metáfora antropomórfica, sobre todo en expresiones relativas a la salud, como “diagnóstico”, “auscultación” o “proceso de curación”. Se exploran además ejemplos de ingeniería cuya fuente son proyecciones conceptuales corporales. Finalmente, abordamos la función de la metáfora visual bajo la teoría de integración conceptual mediante representaciones de ingeniería que evocan la anatomía humana o animal. Metaphor and other imaginative mechanisms that underlie human thought and language such as metonymy are used in everyday and specialised discourse (Lakoff and Johnson 1980; Lakoff and Nuñez 2000) They can also be involved in non- verbal forms of communication (Forceville and Urios-Aparisi 2009; Littlemore et al. this volume). Drawing on metaphor cognitive studies and on conceptual integration theory (Fauconnier 1997; Fauconnier and Turner 2002) this paper examines the occurrence of metaphor in engineering. First, we analyse results from a linguistic corpus formed by research papers from civil engineering journals. These data reveal the use of anthropomorphic metaphor, especially related to health or medical mappings such as “diagnosing”, “auscultation” or “curing”. Then, we explore how engineering notions are instantiated by bodily conceptual mappings according to conceptual integration theory. Finally, the function of visual metaphor is examined with conceptual integration theory by using engineering images evoking parts of human or animal anatomy.

Factors driving the carbon mineralization priming effect in a sandy loam soil amended with different types of biochar

The effect of biochar on the soil carbon mineral- ization priming effect depends on the characteristics of the raw materials, production method and pyrolysis conditions. The goal of the present study is to evaluate the impact of three different types of biochar on physicochemical properties and CO2 emissions of a sandy loam soil. For this purpose, soil was amended with three different biochars (BI, BII and BIII) at a rate of 8 wt % and soil CO2 emissions were measured for 45 days. BI is produced from a mixed wood sieving from wood chip production, BII from a mixture of paper sludge and wheat husks and BIII from sewage sludge. Cumulative CO2 emissions of biochars, soil and amended soil were well fit to a simple first-order kinetic model with correlation coef- ficients (r 2 ) greater than 0.97. Results show a negative prim- ing effect in the soil after addition of BI and a positive prim- ing effect in the case of soil amended with BII and BIII. These results can be related to different biochar properties such as carbon content, carbon aromaticity, volatile matter, fixed carbon, easily oxidized organic carbon or metal and phenolic substance content in addition to surface biochar properties. Three biochars increased the values of soil field capacity and wilting point, while effects over pH and cation exchange capacity were not observed.

Analysis of signal impairment and crosstalk penalty induced by different types of optical filters in 100 Gbps PM-DQPSK based systems

Optical filters are crucial elements in optical communication networks. Their influence toward the optical signal will affect the communication quality seriously. In this paper we will study and simulate the optical signal impairment and crosstalk penalty caused by different kinds of filters, which include Butterworth, Bessel, Fiber Bragg Grating (FBG) and Fabry-Perot (F-P). Signal impairment from filter concatenation effect and crosstalk penalty from out-band and in-band are analyzed from Q-penalty, eye opening penalty (EOP) and optical spectrum. The simulation results show that signal impairment and crosstalk penalty induced by the Butterworth filter is the minimum among these four types of filters. Signal impairment caused by filter concatenation effect shows that when center frequency of all filters is aligned perfectly with the laser's frequency, 12 50-GHz Butterworth filters can be cascaded, with 1-dB EOP. This value is reduced to 9 when the center frequency is misaligned with 5 GHz. In the 50-GHz channel spacing DWDM networks, total Q-penalty induced by a pair of Butterworth filters based demultiplexer and multiplexer is lower than 0.5 dB when the filter bandwidth is in the range of 42-46 GHz.