23,334 research outputs found
The color-singlet contribution to e^+ e^- ->J/psi + X at the endpoint
Recent observations of the J/psi spectrum produced in e^+e^- collisions at
the Upsilon(4S) resonance are in conflict with fixed-order calculations using
Non-Relativsitic QCD effective theory (NRQCD). One problem is an enhancement in
the cross section when the J/psi has maximal energy, due to large perturbative
corrections (Sudakov logarithms). In a recent paper, the Sudakov logarithms in
the color-octet contribution were summed by combining NRQCD with the
Soft-Collinear Effective Theory. However to be consistent, the color-singlet
contributions must also be summed in the endpoint region which was not done in
that paper. In this paper, we sum the leading and next-to-leading logarithms in
the color-singlet contribution to the J/psi production cross section. We find
that the color-singlet cross section is suppressed near endpoint compared to
the fixed order NRQCD prediction.Comment: 17 pages, 7 figure
What Words Do We Use to Lie?: Word Choice in Deceptive Messages
Text messaging is the most widely used form of computer- mediated
communication (CMC). Previous findings have shown that linguistic factors can
reliably indicate messages as deceptive. For example, users take longer and use
more words to craft deceptive messages than they do truthful messages. Existing
research has also examined how factors, such as student status and gender,
affect rates of deception and word choice in deceptive messages. However, this
research has been limited by small sample sizes and has returned contradicting
findings. This paper aims to address these issues by using a dataset of text
messages collected from a large and varied set of participants using an Android
messaging application. The results of this paper show significant differences
in word choice and frequency of deceptive messages between male and female
participants, as well as between students and non-students
Energy Network Communications and Expandable Control Mechanisms
A modular, expandable network requiring little or no calibration is something that is well sought after and would offer great benefits when used for distributed energy generation. Intelligent and adaptive control of such a network offers stability of supply from intermittent sources which, to date, has been hard to achieve.
Key to the effective use of such control systems is communications, specifically the exchange of commands and status information between the control systems and the attached devices. Power-line communications has been used in various applications for years and would offer a good mechanism for interconnecting devices on a power grid without the expense of laying new cabling.
By using clusters of devices managed by an IEMS (Intelligent Energy Management System) in a branching network fashion (not unlike the grid itself) it would be possible to manage large numbers of devices and high speed with relatively low bandwidth usage increasing the usable range of transmission. Implications of this include improving network efficiency through managed power distribution and increased security of supply
Optimizing Energy Storage Participation in Emerging Power Markets
The growing amount of intermittent renewables in power generation creates
challenges for real-time matching of supply and demand in the power grid.
Emerging ancillary power markets provide new incentives to consumers (e.g.,
electrical vehicles, data centers, and others) to perform demand response to
help stabilize the electricity grid. A promising class of potential demand
response providers includes energy storage systems (ESSs). This paper evaluates
the benefits of using various types of novel ESS technologies for a variety of
emerging smart grid demand response programs, such as regulation services
reserves (RSRs), contingency reserves, and peak shaving. We model, formulate
and solve optimization problems to maximize the net profit of ESSs in providing
each demand response. Our solution selects the optimal power and energy
capacities of the ESS, determines the optimal reserve value to provide as well
as the ESS real-time operational policy for program participation. Our results
highlight that applying ultra-capacitors and flywheels in RSR has the potential
to be up to 30 times more profitable than using common battery technologies
such as LI and LA batteries for peak shaving.Comment: The full (longer and extended) version of the paper accepted in IGSC
201
Gate-tunable coherent perfect absorption of terahertz radiation in graphene
Perfect absorption of radiation in a graphene sheet may play a pivotal role
in the realization of technologically relevant optoelectronic devices. In
particular, perfect absorption of radiation in the terahertz (THz) spectral
range would tremendously boost the utility of graphene in this difficult range
of photon energies, which still lacks cheap and robust devices operating at
room temperature. In this work we show that unpatterned graphene flakes
deposited on appropriate substrates can display gate-tunable coherent perfect
absorption (CPA) in the THz spectral range. We present theoretical estimates
for the CPA operating frequency as a function of doping, which take into
account the presence of common sources of disorder in graphene samples.Comment: To appear in 2D Material
- …