1,354,453 research outputs found
Hydrological Assessment of Model Performance and Scenario Analyses of Land Use Change and Climate Change in lowlands of Veneto Region (Italy)
No full textSoil moisture monitoring for climate research: evaluation of a low cost sensor in the framework of the Swiss soil Expperiment (SwissSMEX) campaign
No full textSoil moisture measurements are essential to understand land surface–atmosphere interactions. In this paper we evaluate the performance of the low-cost 10HS capacitance sensor (Decagon Devices, United States) using laboratory and field measurements. Measurements with 10HS sensors of volumetric water content (VWC, Vol.%), integrated absolute soil moisture (millimeters) over the measured soil column, and the loss of soil moisture (millimeters) for rainless days are compared with corresponding measurements from gravimetric samples and time domain reflectometry (TDR) sensors. The field measurements were performed at two sites with different soil texture in Switzerland, and they cover more than a year of parallel measurements in several depths down to 120 cm. For low VWC, both sensor types present good agreement for laboratory and field measurements. Nevertheless, the measurement accuracy of the 10HS sensor reading (millivolts) considerably decreases with increasing VWC: the 10HS sensors tend to become insensitive to variations of VWC above 40 Vol.%. The field measurements reveal a soil type dependency of the 10HS sensor performance, and thus limited applicability of laboratory calibrations. However, with site-specific exponential calibration functions derived from parallel 10HS and TDR measurements, the error of the 10HS compared to the TDR measurements can be decreased for soil moisture contents up to 30 Vol.%, and the day-to-day variability of soil moisture is captured. We conclude that the 10HS sensor is appropriate for setting up dense soil moisture networks when focusing on medium to low VWC and using an established site-specific calibration function. This measurement range is appropriate for several applications in climate research, but the identified performance limitations should be considered in investigations focusing on humid conditions and absolute soil moistur
A state-dependent parameterization of saturated-unsaturated zone interaction
No full textThe relevance of groundwater as an important source of root zone moisture by means of capillary rise is increasingly being recognized. This is partly reflected in many current land surface schemes, which increasingly replace a one-way (i.e., downward) drainage of water by a two-way interaction flux between the root zone and a groundwater system. A fully physically correct implementation of this two-way saturated-unsaturated interaction flux requires transient simulations using the highly nonlinear Richards' equation, which is a computationally demanding approach. We test a classic simple approximation that computes the root zone¿groundwater interaction flux as the net effect of a downward drainage flux and an upward capillary rise flux against the Darcy equation for quasi steady state conditions. We find that for a wet root zone and/or shallow groundwater, the errors within this approximation are significant and of the same magnitude as the interaction flux itself. We present a new closed-form parameterization of the Darcy equation¿based fluxes that accounts both for root zone soil moisture and depth to the water table. Parameter values for this parameterization are listed for 11 different, widely applied soil texture descriptions. The high numerical efficiency of the proposed method makes it suitable for inclusion into demanding applications, e.g., a Monte Carlo framework, or high spatial resolution
Rebirth of the Malacca Shophouse: A typological research: Traditional Values in a Contemporary World
No full textAsian regions change from small towns to a metropolis in the blink of an eye, traditional architecture, and with it traditions itself disappear without notice. This fast renewal has lots of positive effects and the living standard is increasing each day. In the Architecture however we see the tendency of building high dens and large scale buildings, not only designed by Asian architects, but for a great part designed by western architects. My thesis focusses on the question if it is possible to create a small scale architecture in Asia, which can fulfill the modern needs. Melaka The town of Melaka is put on the list of UNESCO world heritage meaning that if a building collapses it has to be rebuild with the same architectonic principles. However, this might turn Melaka into a ‘open air museum’, making it loose its qualities of micro economies and family businesses. I see a chance to rebuild a broken shophouse in a modern way, but sticking to the basic architectural qualities of the shophouse. In some ways the goal is to extract fragments from the historical form and simplify them, in order to apply them later freely on adapted to some contemporary global necessities. Typological Research In order to find these principles a typological research is made to find the basic architectural qualities of the shophouse. All shophouses are researched over time, and important qualities are found. The shophouses, for example, are all build in basic Chinese proportions, consist an ‘air-well’ and have ‘screens’ to separate public and private space.These principles are simplified and applied in the design.ExplorelabArchitectur
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
No full text“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
No full textWe 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
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
van Ommen JR, Teuling M, Nijenhuis J, van Wachem BGM
No full textThe scaling rules using dimensionless groups are investigated using CFD simulations of two scaled fluidized beds with diameters of 15 and 36 cm. Three sets of dimensionless groups are used: the simplified set, the full set, and the full set extended with a dimensionless pressure group. Voidage and pressure data for the two scales are compared using different analysis techniques. The full set gives the largest differences between the two scales. The simplified set and the extended set perform better, but neither lead to complete similarity between the two scales
Disentangling the response of forest and grassland energy exchange to heatwaves under idealized land–atmosphere coupling
No full textThis study investigates the difference in land–atmosphere interactions
between grassland and forest during typical heatwave conditions in order to
understand the controversial results of Teuling et al. (2010) (hereafter T10),
who found the systematic occurrence of higher sensible heat fluxes over
forest than over grassland during heatwaves. With a simple but accurate
coupled land–atmosphere model, we show that existing parametrizations are
able to reproduce the findings of T10 for normal summer and heatwave
conditions. Furthermore, we demonstrate the sensitivity of the coupled system
to changes in incoming radiation and early-morning temperature typical for
European heatwaves.
Our results suggest that the fast atmospheric control of stomatal resistance
can explain the observed differences between grassland and forest. The
atmospheric boundary layer has a buffering function therein: increases in
stomatal resistance are largely compensated for by increases in the potential
evaporation due to atmospheric warming and drying.
In order to disentangle the contributions of differences in several static
and dynamic properties between forest and grassland, we have performed a
virtual experiment with artificial land-use types that are equal to
grassland, but with one of its properties replaced by that of forest. From
these, we confirm the important role of the fast physiological processes that
lead to the closure of stomata. Nonetheless, for a full explanation of T10's
results, the other properties (albedo, roughness and the ratio of minimum
stomatal resistance to leaf-area index) play an important but indirect role;
their influences mainly consist of strengthening the feedback that leads to
the closure of the stomata by providing more energy that can be converted
into sensible heat. The model experiment also confirms that, in line with the
larger sensible heat flux, higher atmospheric temperatures occur over forest.
As our parametrization for stomatal resistance is empirical rather than
mechanical, our study stresses the demand for a better mechanistic
understanding of physiological processes in plants
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