Mixed-mode impedance and reflection coefficient of two-port devices

From the point of view of mixed-mode scattering parameters, Smm, a two-port device can be excited using different driving conditions. Each condition leads to a particular set of input reflection and input impedance coefficient definitions that should be carefully applied depending on the type of excitation and symmetry of the two-port device. Therefore, the aim of this paper is to explain the general analytic procedure for the evaluation of such reflection and impedance coefficients in terms of mixed-mode scattering parameters. Moreover, the driving of a two-port device as a one-port device is explained as a particular case of a two-port mixed-mode excitation using a given set of mixed-mode loads. The theory is applied to the evaluation of the quality factor, Q, of symmetrical and non- symmetrical inductors.Ministerio de Innovación y Ciencia TEC2010-14825/MIC, TEC2010-21484Junta de Andalucía TIC-253

Consideraciones sobre la dinámica geomorfológica actual de laderas semiáridas de la Depresión del Ebro: el caso de la Val de las Lenas (término municipal de María de Huerva, Zaragoza, España)

[Resumen] En este trabajo se realiza una aproximación al funcionamiento geomorfológico actual de las vales del semiárido aragonés. Las investigaciones contemplan sucesivas aproximaciones, en las que se analizarán: (1) la evolución de humedad en el suelo en diferentes profundidades y posiciones de ladera, (2) las variaciones de la textura del depósito y (3) la simulación de lluvia. Los resultados indican la posible existencia de un funcionamiento hidrológico dislocado a lo largo de la ladera entre el talud superior y los niveles basales. A lo largo del relleno, además, la franja superior parece depender hidrológicamente de su proximidad al talud rocoso adyacente (funcionamiento alóctono), mientras que el depósito de val parece comportarse hidrológicmente de manera autóctona. Entre las partes altas y bajas del relleno de val se aprecia una inversión de las condiciones hídricas que definen su potencial biológico, cuyo reparto espacial es inverso al esperado.[Abstract] We have studied the geomorphological behaviour of slope in a semiarid landscape (NE inland Spain). The approach have been done by the analysis of soil water evolution, particle size analysis and rainfall simulation from top to bottom of slope. Results suggest the posibility of hidrological compartimentation between upper free face and talus; talus is not homogeneous, and there exist a strip in the contact zone with upper free face which change the hidrological regime from upper to lower part of talus

Evaluación del dispositivo Pavement Quality Indicator (PQI) en la determinación de la densidad in situ de mezclas fabricadas con emulsión bituminosa

The Pavement Quality Indicator (PQI) is a non-nuclear gauge used for the on-site density measurement of asphalt pavements without the need to extract core samples. Previous studies of hot asphalt mixes found that PQI density readings were very similar to laboratory density measurements of pavement cores. This paper describes the first stage of a research project whose objective is to analyze PQI density measurements of mixes manufactured with an asphalt emulsion binder. The PQI density variability for such mixes was verified and compared with the results obtained with other on-site methods for measuring pavement density.El equipo Pavement Quality Indicator es un dispositivo para la determinación de densidad in situ en pavimentos asfálticos sin extracción de testigos. Las experiencias con este equipo en mezclas bituminosas en caliente, recogidas en diferentes fuentes bibliográficas, muestran que las densidades medidas in situ con el PQI son muy similares a las obtenidas mediante la extracción de testigos. En este artículo se expone la primera etapa de un proyecto de investigación que tiene por objeto analizar los resultados de mediciones efectuadas con PQI en mezclas bituminosas donde se utiliza emulsión asfáltica como ligante. Se comprueba la variabilidad de la densidad obtenida con el equipo para este tipo de mezclas, y se comparan los resultados con otros métodos de medida de densidad in situ

U Geminorum: a test case for orbital parameters determination

High-resolution spectroscopy of U Gem was obtained during quiescence. We did not find a hot spot or gas stream around the outer boundaries of the accretion disk. Instead, we detected a strong narrow emission near the location of the secondary star. We measured the radial velocity curve from the wings of the double-peaked H$\alpha$ emission line, and obtained a semi-amplitude value that is in excellent agreement with the obtained from observations in the ultraviolet spectral region by Sion et al. (1998). We present also a new method to obtain K_2, which enhances the detection of absorption or emission features arising in the late-type companion. Our results are compared with published values derived from the near-infrared NaI line doublet. From a comparison of the TiO band with those of late type M stars, we find that a best fit is obtained for a M6V star, contributing 5 percent of the total light at that spectral region. Assuming that the radial velocity semi-amplitudes reflect accurately the motion of the binary components, then from our results: K_em = 107+/-2 km/s; K_abs = 310+/-5 km/s, and using the inclination angle given by Zhang & Robinson(1987); i = 69.7+/-0.7, the system parameters become: M_WD = 1.20+/-0.05 M_sun,; M_RD = 0.42+/-0.04 M_sun; and a = 1.55+/- 0.02 R_sun. Based on the separation of the double emission peaks, we calculate an outer disk radius of R_out/a ~0.61, close to the distance of the inner Lagrangian point L_1/a~0.63. Therefore we suggest that, at the time of observations, the accretion disk was filling the Roche-Lobe of the primary, and that the matter leaving the L_1 point was colliding with the disc directly, producing the hot spot at this location.Comment: 36 pages, 14 figures, ccepted for publication in A

New Spectroscopy of U Gem

We present new optical spectroscopic observations of U Geminorum obtained during a quiescent stage. We performed a radial velocity analysis of three Balmer emission lines yielding inconsistent results. Assuming that the radial velocity semi amplitude accurately reflects the motion of the white dwarf, we arrive at masses for the primary which are in the range of M_wd= 1.21 - 1.37 M_Sun. Based on the internal radial velocity inconsistencies and results produced from the Doppler tomography -- wherein we do not detect emission from the hot spot, but rather an intense asymmetric emission overlaying the disc, reminiscent of spiral arms -- we discuss the possibility that the overestimation of the masses may be due to variations of gas opacities and a partial truncation of the disc.Comment: 16 pages, 10 figures, 3 tables, to be published on RevMexAA. arXiv admin note: text overlap with arXiv:2112.0343

Phytoplankton, bacterioplankton and nitrate reductase activity distribution in relation to physical structure in the northern Alborán Sea and Gulf of Cadiz (southern Iberian Peninsula)

The IctioAlborán-Cadiz 95 cruise (July 1995) covered the northwest sector of the Alborán Sea, the Straits of Gibraltar and the Gulf of Cadiz. We present and discuss the distribution of phytoand bacterioplankton abundance, nitrate concentration and nitrate reductase (NR) activity according to circulation patterns described previously in the literature. The water-column integrated values of chlorophyll-a in the Alborán Sea were higher and more variable (12 to 318 mg m⁻³) than in the Gulf of Cadiz (3 to 49 mg m⁻³). This reflects the higher dynamism of the Alborán sector, related to the existence of characteristic mesoscale physical structures. The plankton (2-80 μm equivalent spherical diameter) in the upwelling region of the Alborán Sea had a biovolume 30 times higher than in the nutrient-poorer water of the Gulf of Cadiz. Large organisms were abundant and dominated the size spectrum of one coastal station in the Alborán zone, whereas the slope of the size spectrum became more negative at the Gulf of Cadiz station, as a consequence of the dominance of small cells. Bacterial abundance maxima ( 3 X 10⁶ bact ml⁻¹) also occurred in the upwelling region. We found relatively high nitrate and chlorophyll a concentrations in Cape Trafalgar's cold surface waters, probably due to the interaction between topography and strong tidal currents. The spatial pattern of the NR activity is discussed according to chlorophyll a, nitrate and bacteria distributions. The existence of high NR activity but low chlorophyll a and bacterial abundance suggests that this could be related with dissimilatory activity in large-sized particles.La campaña IctioAlborán-Cádiz 95 (julio de 1995) cubrió el sector noroeste del mar de Alborán, estrecho de Gibraltar y golfo de Cádiz. En este trabajo se presentan y discuten las distribuciones de abundancia de fitoplancton y bacterioplancton, concentración de nitrato y actividad nitrato reductasa (NR) de acuerdo con los patrones de circulación descritos en la bibliografía. Los valores de clorofila a integrados en la columna de agua en Alborán fueron mayores y más variables (12 a 318 mg/m³) que en el golfo de Cádiz (3 a 49 mg/m³). Esto refleja el mayor dinamismo de la zona de Alborán, relacionado con la existencia de estructuras físicas características a mesoescala. El análisis de la comunidad nano-microplanctónica (2-80 μm, diametro esférico equivalente) de la región de afloramiento del mar de Alborán mostró un biovolumen 30 veces mayor que el de aguas más pobres en nutrientes del golfo de Cádiz. Por otro lado, el espectro de tamaños en una estación costera de Alborán está dominado por organismos planctónicos grandes, mientras que la pendiente del espectro de tamaño se hace más negativa en una estación del golfo de Cádiz, como consecuencia de la mayor abundancia de plancton de pequeño tamaño. En la región de afloramiento se dieron también máximos de abundancia bacteriana ( 3 X 10⁶ bact ml⁻¹). Se han encontrado valores relativamente altos de nitrato y clorofila a en las frías aguas superficiales cercanas al cabo de Trafalgar, lo que se debe, probablemente, a la interacción entre topografía y fuertes corrientes mareales. Se discute el patrón espacial de la actividad NR en relación con las distribuciones de clorofila a, nitrato y bacterias. En muestras con valores elevados de actividad NR pero bajos de clorofila y abundancia de bacterias, se sugiere que esta actividad se relaciona con actividad disimilatoria en agregados de gran tamaño.Instituto Español de Oceanografí

Phytoplankton pigment distribution in the northwestern Alboran Sea and meteorological forcing: A remote sensing study

A set of weekly-composite SeaWiFS (Sea-viewing Wide Field of view Sensor) imagery (from 1998 to 2004) has been used to asses the temporal and spatial variability of the surface chlorophyll distribution in the Northwestern Alboran Sea. Empirical Orthogonal Function (EOF) analysis of the images series shows the existence of three different regions in which surface chlorophyll presents a homogeneous temporal behavior in the neighborhood of the Strait of Gibraltar.The temporal patterns of surface chlorophyll concentrations in each region have been characterized by studying the role of several forcing factors, mainly the zonal component of the wind field.The first identified region occupies the coastal area in front of Estepona and Málaga and shows the highest chlorophyll concentration in the entire region of study in absence of easterly winds. A second region is located far offshore, in the zone usually occupied by the Atlantic jet entering the Alboran Sea, showing high concentrations of chlorophyll when the easterlies blow. Finally, a third region has been situated in the normal location of the Western Alboran Gyre (WAG).The zonal wind field arises as a main forcing function in the modulation of the intensity and location of the upwelling processes in the area, while the entrance of the Atlantic jet seems to be the main agent feeding of all these processes

The Expanding Nebular Remnant of the Recurrent Nova RS Ophiuchi (2006): II. Modeling of Combined Hubble Space Telescope Imaging and Ground-based Spectroscopy

We report Hubble Space Telescope imaging, obtained 155 and 449 days after the 2006 outburst of the recurrent nova RS Ophiuchi, together with ground-based spectroscopic observations, obtained from the Observatorio Astron\'omico Nacional en San Pedro M\'artir, Baja California, M\'exico and at the Observatorio Astrof\'isico Guillermo Haro, at Cananea, Sonora, M\'exico. The observations at the first epoch were used as inputs to model the geometry and kinematic structure of the evolving RS Oph nebular remnant. We find that the modeled remnant comprises two distinct co-aligned bipolar components; a low-velocity, high-density innermost (hour glass) region and a more extended, high-velocity (dumbbell) structure. This overall structure is in agreement with that deduced from radio observations and optical interferometry at earlier epochs. We find that the asymmetry observed in the west lobe is an instrumental effect caused by the profile of the HST filter and hence demonstrate that this lobe is approaching the observer. We then conclude that the system has an inclination to the line of sight of 39$^{+1}_{-10}$ degrees. This is in agreement with the inclination of the binary orbit and lends support to the proposal that this morphology is due to the interaction of the outburst ejecta with either an accretion disk around the central white dwarf and/or a pre-existing red giant wind that is significantly denser in the equatorial regions of the binary than at the poles. The second epoch HST observation was also modeled. However, as no spectra were taken at this epoch, it is more difficult to constrain any model. Nevertheless, we demonstrate that between the two HST epochs the outer dumbbell structure seems to have expanded linearly.Comment: 33 pages, 9 figures, 1 table, accepted for publication in Ap

Variability of early autumn planktonic assemblages in the strait of Gibraltar: a regionalization analysis

The Strait of Gibraltar (SG) is the only connection of the Mediterranean Sea with the global circulation. The SG is an outstanding marine region to explore physical-biological coupling of pelagic communities due to its hydrodynamic complexity, including strong tidal forcing and marked spatial gradients and fronts. The authors have unravelled the role of the fortnightly tidal scale (spring and neap tides) and local processes (upwelling and tidal-topographic mixing) that shape planktonic assemblages in the Strait. To do so, an oceanographic cruise was taken in early autumn 2008 with a high-resolution grid sampling and spring/neap tidal conditions. The planktonic features were captured using different automatic and semi-automatic techniques of plankton analyses (flow cytometry, FlowCAM, LOPC and Ecotaxa) that allowed covering a wide range of sizes of the community from pico- to mesoplankton. The SG was sectorized into two clusters based on the biogeochemical and main water column properties. Cluster 1 (CL1) covered shallow productive areas around Cape Trafalgar (CT). CL1 presented higher concentrations of chlorophyll and nutrients, and phytoplankton was mostly represented by Synechococcus and coastal diatoms while zooplankton had the highest percentage of meroplankton (31%). In contrast, cluster 2 (CL2) covered open ocean waters and presented more oligotrophic features, i.e. nitrogen-depleted waters with lower chlorophyll concentrations and a picoplankton community dominated by Prochlorococcus and holoplankton predominance in mesozooplankton. Under early autumn conditions with overall nutrient-depleted and stratified waters, the CT area emerges as an ecosystem where the constant tidal mixing and nutrients supply is coupled with an active production also being favored by high residence times and finally shaping a plankton community with unique features in the area.En prensa0,56