15,849 research outputs found
The Technical and Economical Analysis of a Centralized Air-Conditioning System with Cold Storage Refrigeration in High-Rise Residential Buildings
In recent years, the application of a centralized air-conditioning system (CACS) with cold storage refrigeration in high-rise residential buildings has gradually increased. Due to the large difference between civil residential buildings and commercial buildings, characteristics such as the cooling load in summer and the storey height must be considered in the design of the air-conditioning system, and the cold storage equipment and the cold supplying means must be properly selected. The option of establishing centralized air-conditioning equipment with cold storage and supplying unified cold in high-rise residential buildings is analyzed objectively with technical and economical methods in this paper. It is not true that the option of supplying unified cold can save energy all the time. CACS with cold storage will not always be economical. Based on a 27-floor building, the running costs in summer and the first costs are both compared between CACS with and without cold storage refrigeration. The cold storage method selected will significantly impact the residents
DeltaPhish: Detecting Phishing Webpages in Compromised Websites
The large-scale deployment of modern phishing attacks relies on the automatic
exploitation of vulnerable websites in the wild, to maximize profit while
hindering attack traceability, detection and blacklisting. To the best of our
knowledge, this is the first work that specifically leverages this adversarial
behavior for detection purposes. We show that phishing webpages can be
accurately detected by highlighting HTML code and visual differences with
respect to other (legitimate) pages hosted within a compromised website. Our
system, named DeltaPhish, can be installed as part of a web application
firewall, to detect the presence of anomalous content on a website after
compromise, and eventually prevent access to it. DeltaPhish is also robust
against adversarial attempts in which the HTML code of the phishing page is
carefully manipulated to evade detection. We empirically evaluate it on more
than 5,500 webpages collected in the wild from compromised websites, showing
that it is capable of detecting more than 99% of phishing webpages, while only
misclassifying less than 1% of legitimate pages. We further show that the
detection rate remains higher than 70% even under very sophisticated attacks
carefully designed to evade our system.Comment: Preprint version of the work accepted at ESORICS 201
Renormalization of tensor-network states
We have discussed the tensor-network representation of classical statistical
or interacting quantum lattice models, and given a comprehensive introduction
to the numerical methods we recently proposed for studying the tensor-network
states/models in two dimensions. A second renormalization scheme is introduced
to take into account the environment contribution in the calculation of the
partition function of classical tensor network models or the expectation values
of quantum tensor network states. It improves significantly the accuracy of the
coarse grained tensor renormalization group method. In the study of the quantum
tensor-network states, we point out that the renormalization effect of the
environment can be efficiently and accurately described by the bond vector.
This, combined with the imaginary time evolution of the wavefunction, provides
an accurate projection method to determine the tensor-network wavfunction. It
reduces significantly the truncation error and enable a tensor-network state
with a large bond dimension, which is difficult to be accessed by other
methods, to be accurately determined.Comment: 18 pages 23 figures, minor changes, references adde
Demonstration of Temporal Distinguishability in a Four-Photon State and a Six-Photon State
An experiment is performed to demonstrate the temporal distinguishability of
a four-photon state and a six-photon state, both from parametric
down-conversion. The experiment is based on a multi-photon interference scheme
in a recent discovered NOON-state projection measurement. By measuring the
visibility of the interference dip, we can distinguish the various scenarios in
the temporal distribution of the pairs and thus quantitatively determine the
degree of temporal (in)distinguishability of a multi-photon state
Information-Theoretic Measure of Genuine Multi-Qubit Entanglement
We consider pure quantum states of N qubits and study the genuine N-qubit
entanglement that is shared among all the N qubits. We introduce an
information-theoretic measure of genuine N-qubit entanglement based on
bipartite partitions. When N is an even number, this measure is presented in a
simple formula, which depends only on the purities of the partially reduced
density matrices. It can be easily computed theoretically and measured
experimentally. When N is an odd number, the measure can also be obtained in
principle.Comment: 5 pages, 2 figure
Plaquette order and deconfined quantum critical point in the spin-1 bilinear-biquadratic Heisenberg model on the honeycomb lattice
We have precisely determined the ground state phase diagram of the quantum
spin-1 bilinear-biquadratic Heisenberg model on the honeycomb lattice using the
tensor renormalization group method. We find that the ferromagnetic,
ferroquadrupolar, and a large part of the antiferromagnetic phases are stable
against quantum fluctuations. However, around the phase where the ground state
is antiferroquadrupolar ordered in the classical limit, quantum fluctuations
suppress completely all magnetic orders, leading to a plaquette order phase
which breaks the lattice symmetry but preserves the spin SU(2) symmetry. On the
evidence of our numerical results, the quantum phase transition between the
antiferromagnetic phase and the plaquette phase is found to be either a direct
second order or a very weak first order transition.Comment: 6 pages, 9 figures, published versio
Thermodynamic properties of tetrameric bond-alternating spin chains
Thermodynamic properties of a tetrameric bond-alternating Heisenberg spin
chain with ferromagnetic-ferromagnetic-antiferromagnetic-antiferromagnetic
exchange interactions are studied using the transfer-matrix renormalization
group and compared to experimental measurements. The temperature dependence of
the uniform susceptibility exhibits typical ferrimagnetic features. Both the
uniform and staggered magnetic susceptibilities diverge in the limit ,
indicating that the ground state has both ferromagnetic and antiferromagnetic
long-range orders. A double-peak structure appears in the temperature
dependence of the specific heat. Our numerical calculation gives a good account
for the temperature and field dependence of the susceptibility, the
magnetization, and the specific heat for Cu(3-Clpy)(N)
(3-Clpy=3-Chloroyridine).Comment: 8 pages, 12 figures; Replaced with final version accepted in Phys.
Rev.
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Electron quantum interference in epitaxial antiferromagnetic NiO thin films
The electron reflectivity from NiO thin films grown on Ag(001) has been systematically studied as a function of film thickness and electron energy. A strong electron quantum interference effect was observed from the NiO film, which is used to derive the unoccupied band dispersion above the Fermi surface along the Γ-X direction using the phase accumulation model. The experimental bands agree well with first-principles calculations. A weaker electron quantum interference effect was also observed from the CoO film
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