1,443 research outputs found
Evaluation of Infiltration in Furrow Irrigation Part 1: Recession Flow
Recession flow in a large field can be significant from the point of view of water-use efficiency. This is particularly
important in the case where the furrow field is long, thus the receding flow can contribute to the irrigation of crops.
Indeed, recession flow is very significant in the surge method of furrow irrigation. In the continuous mode of
operation in very long furrows the amount of recession flow can be significant. Herein is presented the mathematical
modelling of the recession flow. The analytical procedure is based on the kinematic wave approach used for the
simulation of the advance-flow trajectory for furrows. This resulting recession simulation was found to be very useful
for the evaluation of the basic infiltration rate in a furrow
Evaluation of Infiltration in Furrow Irrigation Part 2 : Basic Infiltration Rate
Part 1 of this title was the simulation of the recession flow in a furrow. This part
uses the recession simulation further to establish the basic infiltration rate in
a furrow and, therefore, the infiltration characteristics in a furrow. Determining
infiltration in a furrow is complicated by the dynamic flow nature of irrigation
water, as well as the geometric shape of the channel, among other factors. The
evaluation of this infiltration in furrows is important in order to evaluate the
water use in such irrigation systems. The use of the Kostiakov equation in its
extended form has been suggested for the determination of infiltration characteristics
in a furrow. This equation, however, depends on the evaluation of
the long-term basic infiltration rate, which can be determined practically by a
long-term tedious inflow/outflow hydrograph of the irrigation event. An analytical
method based on the kinematic wave theory and recession flow data is
proposed here to evaluate the long-term basic infiltration rate pertinent to the
correct evaluation of the infiltration flow characteristics in a furrow
Concurrence of superposition
The bounds on concurrence of the superposition state in terms of those of the
states being superposed are studied in this paper. The bounds on concurrence
are quite different from those on the entanglement measure based on von Neumann
entropy (Phys. Rev. Lett. 97, 100502 (2006)). In particular, a nonzero lower
bound can be provided if the states being superposed are properly constrained.Comment: 4 page
Existence Criterion of Genuine Tripartite Entanglement
In this paper, an intuitive mathematical formulation is provided to
generalize the residual entanglement for tripartite systems of qubits [Phys.
Rev. A 61, 052306 (2000)] to the tripartite systems in higher dimension. The
spirit lies in the tensor treatment of tripartite pure states [Phys. Rev. A 72,
022333 (2005)]. A distinct characteristic of the present generalization is that
the formulation for higher dimensional systems is invariant under permutation
of the subsystems, hence is employed as a criterion to test the existence of
genuine tripartite entanglement. Furthermore, the formulation for pure states
can be conveniently extended to the case of mixed states by utilizing the
Kronecker product approximate technique. As applications, we give the analytic
approximation of the criterion for weakly mixed tripartite quantum states and
consider the existence of genuine tripartite entanglement of some weakly mixed
states.Comment: 6 pages, 2 figure
A co-recommendation algorithm for web searching
This paper presents an approach called the Co-Recommendation Algorithm, which consists of the features of the recommendation rule and the co-citation algorithm. The algorithm addresses some challenges that are essential for further searching and recommendation algorithms. It does not require users to provide a lot of interactive communication. Furthermore, it supports other queries, such as keyword, URL and document investigations. When the structure is compared to other algorithms, the scalability is noticeably easier. The high online performance can be obtained as well as the repository computation, which can achieve a high group-forming accuracy using only a fraction of Web pages from a cluster. <br /
The Association Between Student Wellness and Student Engagement in School
School engagement has been identified as an important construct associated with student achievement, school completion, and more recently, student well-being. The present study included data from 200 ninth grade students of diverse ethnic groups (African American, Hispanic, & White) to explore dimensions of student wellness and their association with student engagement in school. Adolescents completed the Child and Adolescent Wellness Scale (CAWS) and the Student Engagement in School Questionnaire (SEQ). Results revealed that students viewed themselves positively on both measures, the two measures demonstrated adequate internal consistency, and all 10 dimensions of the CAWS were significantly related to student engagement in school. The current study provides support for dimensions of wellness contributing to measured student engagement in school, and discusses the potential of wellness concepts contributing to school mental health
On the Conductance Sum Rule for the Hierarchical Edge States of the Fractional Quantum Hall Effect
The conductance sum rule for the hierarchical edge channel currents of a
Fractional Quantum Hall Effect state is derived analytically within the
Haldane-Halperin hierarchy scheme. We provide also an intuitive interpretation
for the hierarchical drift velocities of the edge excitations.Comment: 11 pages, no figure, Revtex 3.0, IC/93/329, ASITP-93-5
Andromeda's Parachute: A Bright Quadruply Lensed Quasar at z=2.377
We present Keck Cosmic Web Imager spectroscopy of the four putative images of
the lensed quasar candidate J014709+463037 recently discovered by Berghea et
al. (2017). The data verify the source as a quadruply lensed, broad
absorption-line quasar having z_S = 2.377 +/- 0.007. We detect intervening
absorption in the FeII 2586, 2600, MgII 2796, 2803, and/or CIV 1548, 1550
transitions in eight foreground systems, three of which have redshifts
consistent with the photometric-redshift estimate reported for the lensing
galaxy (z_L ~ 0.57). By virtue of their positions on the sky, the source images
probe these absorbers over transverse physical scales of ~0.3-21 kpc,
permitting assessment of the variation in metal-line equivalent width W_r as a
function of sight-line separation. We measure differences in W_r,2796 of <40%
across all sight-line pairs subtending 7-21 kpc, suggestive of a high degree of
spatial coherence for MgII-absorbing material. W_r,2600 is observed to vary by
>50% over the same scales across the majority of sight-line pairs, while CIV
absorption exhibits a wide range in W_r,1548 differences of ~5-80% within
transverse distances less than ~3 kpc. J014709+463037 is one of only a handful
of z > 2 quadruply lensed systems for which all four source images are very
bright (r = 15.4-17.7 mag) and are easily separated in ground-based seeing
conditions. As such, it is an ideal candidate for higher-resolution
spectroscopy probing the spatial variation in the kinematic structure and
physical state of intervening absorbers.Comment: Submitted to ApJL. 9 pages, 3 figures. Uses aastex61 forma
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