4,745 research outputs found
Integrable Minisuperspace Models with Liouville Field: Energy Density Self-Adjointness and Semiclassical Wave Packets
The homogeneous cosmological models with a Liouville scalar field are
investigated in classical and quantum context of Wheeler-DeWitt
geometrodynamics. In the quantum case of quintessence field with potential
unbounded from below and phantom field, the energy density operators are not
essentially self-adjoint and self-adjoint extensions contain ambiguities.
Therefore the same classical actions correspond to a family of distinct quantum
models. For the phantom field the energy spectrum happens to be discrete. The
probability conservation and appropriate classical limit can be achieved with a
certain restriction of the functional class. The appropriately localized wave
packets are studied numerically using the Schrodinger's norm and a conserved
Mostafazadeh's norm introduced from techniques of pseudo-Hermitian quantum
mechanics. These norms give a similar packet evolution that is confronted with
analytical classical solutions.Comment: Main points emphasized, less important material shortened; 24 pages,
13 figure
The density-functional theory of quantum droplets
In quantum droplets, the mean-field energy is comparable to the
Lee-Huang-Yang (LHY) energy. In the Bogoliubov theory, the LHY energy of the
quantum droplet has an imaginary part, but it is neglected for practical
purposes. So far, most theoretical studies of quantum droplets have been based
on the extended Gross-Pitaevskii (GP) equation obtained by adding the LHY
energy to the GP equation. In this article, we present the density-functional
theory of quantum droplets. In our approach, the quantum fluctuations in
quantum droplets, as described by an effective action, generate the correlation
energy which is real and can be determined self-consistently. Our results are
consistent with the extended GP equation in the dilute limit, and the
implications to current experiments on quantum droplets are discussed
Learning Visual Features from Snapshots for Web Search
When applying learning to rank algorithms to Web search, a large number of
features are usually designed to capture the relevance signals. Most of these
features are computed based on the extracted textual elements, link analysis,
and user logs. However, Web pages are not solely linked texts, but have
structured layout organizing a large variety of elements in different styles.
Such layout itself can convey useful visual information, indicating the
relevance of a Web page. For example, the query-independent layout (i.e., raw
page layout) can help identify the page quality, while the query-dependent
layout (i.e., page rendered with matched query words) can further tell rich
structural information (e.g., size, position and proximity) of the matching
signals. However, such visual information of layout has been seldom utilized in
Web search in the past. In this work, we propose to learn rich visual features
automatically from the layout of Web pages (i.e., Web page snapshots) for
relevance ranking. Both query-independent and query-dependent snapshots are
considered as the new inputs. We then propose a novel visual perception model
inspired by human's visual search behaviors on page viewing to extract the
visual features. This model can be learned end-to-end together with traditional
human-crafted features. We also show that such visual features can be
efficiently acquired in the online setting with an extended inverted indexing
scheme. Experiments on benchmark collections demonstrate that learning visual
features from Web page snapshots can significantly improve the performance of
relevance ranking in ad-hoc Web retrieval tasks.Comment: CIKM 201
Semi-classical predictions of cosmological wave-packets from ridge-lines
We introduce a concept of ridge-lines to investigate the semi-classical
prediction from wave-packets with arbitrary width in conventional quantum
mechanics and the Wheeler--DeWitt quantum cosmology. Two primary approaches are
applied to the exact calculation of the ridge-lines, namely the contour and the
stream approach. Moreover, aspects of these are discussed and compared to other
scenarios and approaches, i.e. the narrow WKB wave-packets and the
first-derivative test. As the main result, we show that the semi-classical
predictions in toy models have more abundant solutions than in the classical
theory, and most interestingly they may deviate from classical solutions due to
the quantum corrections.Comment: 44 pages, 14 figures, 3 table
Japan Sea Thermohaline Structure and Circulation. Part II: A Variational P-Vector Method
The second part of this work investigates the seasonal variabilities of the Japan/East Sea (JES) circulation
using the U.S. Navy Generalized Digital Environmental Model (GDEM) climatological temperature and salinity
dataset (public domain) on a 0.5° x 0.5° grid. A variational P-vector method was developed to invert the velocity
field. The GDEM for the JES was built up on historical (1930–97) 136 509 temperature and 52 572 salinity
profiles. The climatological mean and seasonal variability of the current systems are well inverted, especially
the Tsushima Warm Current and its bifurcation, the East Korean Warm Current (EKWC), the Japan nearshore
branch, the confluence of the EKWC, and the North Korean Cold Current near the Korean coast and flows
northeastward along the subpolar front, and a mesoscale anticyclonic eddy in the Ulleng/Tsushima Basin. Furthermore, this method has the capability to invert flow reasonably well across the shallow straits such as the
Tsushima/Korea, Tsugaru, and Soya Straits. The GDEM temperature and salinity and the inverted velocity fields
provide balanced initial fields for JES numerical modeling and simulation.Office of Naval ResearchNaval Oceanographic OfficeNaval Postgraduate SchoolN0001401WR2021
Career development impact on architecture undergrads’ employment: learning motivation mediation
This study, utilizing the expectancy-value theory, examines the relationship between career development, learning motivation, and employment capabilities among Chinese architecture undergraduates. Surveying 319 students from five Chinese universities, the research reveals that career development has a positive impact on both employment capabilities and learning motivation. Learning motivation, in turn, positively affects employment capabilities and acts as a mediator between career development and employment capabilities. These findings underscore the significance of proactive career planning, goal setting, and intrinsic learning motivation in enhancing students' employment capabilities. For practical applications, educational institutions can design comprehensive career development programs to assist students in defining career goals and igniting intrinsic motivation for learning, thereby fostering career success and employability among architecture students
- …