144 research outputs found
Artificial non-Abelian lattice gauge fields for photons in the synthetic frequency dimension
Non-Abelian gauge fields give rise to nontrivial topological physics. Here we
develop a scheme to create an arbitrary SU(2) lattice gauge field for photons
in the synthetic frequency dimension using an array of dynamically modulated
ring resonators. The photon polarization is taken as the spin basis to
implement the matrix-valued gauge fields. Using a non-Abelian generalization of
the Harper-Hofstadter Hamiltonian as a specific example, we show that the
measurement of the steady-state photon amplitudes inside the resonators can
reveal the band structures of the Hamiltonian, which show signatures of the
underlying non-Abelian gauge field. These results provide opportunities to
explore novel topological phenomena associated with non-Abelian lattice gauge
fields in photonic systems
Multi-dimensional band structure spectroscopy in the synthetic frequency dimension
The concept of synthetic dimensions in photonics provides a versatile
platform in exploring multi-dimensional physics. Many of these physics are
characterized by band structures in more than one dimensions. Existing efforts
on band structure measurements in the photonic synthetic frequency dimension
however are limited to either one-dimensional Brillouin zones or
one-dimensional subsets of multi-dimensional Brillouin zones. Here we
theoretically propose and experimentally demonstrate a method to fully measure
multi-dimensional band structures in the synthetic frequency dimension. We use
a single photonic resonator under dynamical modulation to create a
multi-dimensional synthetic frequency lattice. We show that the band structure
of such a lattice over the entire multi-dimensional Brillouin zone can be
measured by introducing a gauge potential into the lattice Hamiltonian. Using
this method, we perform experimental measurements of two-dimensional band
structures of a Hermitian and a non-Hermitian Hamiltonian. The measurements
reveal some of the general properties of point-gap topology of the
non-Hermitian Hamiltonian in more than one dimensions. Our results demonstrate
experimental capabilities to fully characterize high-dimensional physical
phenomena in the photonic synthetic frequency dimension
Application of Cross-Linked Polyborosiloxanes and Organically Modified Boron Silicate Binders in Silicon-Containing Anodes for Lithium-Ion Batteries
To determine the effect of cross-linking in polymer binders on gravimetric capacity and retention in charge/discharge cycling of lithium-ion batteries containing silicon anodes, polymers with a varied chemiophysical characters have been studied as electrode binders. Here we report the utilization of cross-linked polyborosiloxanes and a boron-modified organosilicate as binders for nanoparticulate silicon-containing anodes for lithium-ion batteries. We show that highly cross-linked binders enable a large degree of capacity to be accessed and that capacity retention is greater when the electrodes are cycled in half cells. More extensive analysis of the boron-modified organosilicate is further explored
Modelling Ice and Wax Formation in a Pipeline in the Arctic Environment
PresentationIn the Arctic environment, fluid temperature in pipeline can drop below the freezing point of water, which causes wax and ice to form on pipeline surface. Solid formation on pipeline surface can lead to flow assurance and process safety issues, such as blockage of pipeline, pipeline component failure, and the release of hazardous liquid. The blockage of pipeline can cause additional burden or failure to pumping system. Remediating the plugging requires shutdown of pipeline operation, which cause tremendous cost and delay to the entire production system. Ice and wax deposition in pipeline is a slow process. Pigging operation can be used to remove the deposits on pipeline surface. However, if deposition is too thick, pipeline blockage can still occur. In order to prevent pipeline blockage, ice and wax deposition rates are required to be estimated. This paper investigates ice and wax deposition rates in a 90 km pipeline. A fundamental model for both ice and wax deposition is proposed using first principles of heat and mass transfer. The interaction between water and wax is analysed
Optical neural network architecture for deep learning with the temporal synthetic dimension
The physical concept of synthetic dimensions has recently been introduced
into optics. The fundamental physics and applications are not yet fully
understood, and this report explores an approach to optical neural networks
using synthetic dimension in time domain, by theoretically proposing to utilize
a single resonator network, where the arrival times of optical pulses are
interconnected to construct a temporal synthetic dimension. The set of pulses
in each roundtrip therefore provides the sites in each layer in the optical
neural network, and can be linearly transformed with splitters and delay lines,
including the phase modulators, when pulses circulate inside the network. Such
linear transformation can be arbitrarily controlled by applied modulation
phases, which serve as the building block of the neural network together with a
nonlinear component for pulses. We validate the functionality of the proposed
optical neural network for the deep learning purpose with examples handwritten
digit recognition and optical pulse train distribution classification problems.
This proof of principle computational work explores the new concept of
developing a photonics-based machine learning in a single ring network using
synthetic dimensions, which allows flexibility and easiness of reconfiguration
with complex functionality in achieving desired optical tasks
Evaluation of the stress singularities of plane V-notches in bonded dissimilar materials
According to the linear theory of elasticity, there exists a combination of different orders of stress singularity at a V-notch tip of bonded dissimilar materials. The singularity reflects a strong stress concentration near the sharp V-notches. In this paper, a new way is proposed
in order to determine the orders of singularity for two-dimensional V-notch problems. Firstly, on the basis of an asymptotic stress field in terms of radial coordinates at the V-notch tip, the governing equations of the elastic theory are transformed into an eigenvalue problem of ordinary differential equations (ODEs) with respect to the circumferential coordinate h around the notch tip. Then the interpolating matrix method established by the first author is further developed to solve the general eigenvalue problem. Hence, the singularity orders of the V-notch problem are determined through solving the corresponding
ODEs by means of the interpolating matrix method. Meanwhile, the associated eigenvectors of the displacement and stress fields near the V-notches are also obtained. These functions are essential in calculating the amplitude of the stress field described as generalized stress intensity factors of the V-notches. The present method is also available to deal with the plane V-notch problems in bonded orthotropic multi-material. Finally, numerical
examples are presented to illustrate the accuracy and the effectiveness of the method
High Altitude test of RPCs for the ARGO-YBJ experiment
A 50 m**2 RPC carpet was operated at the YangBaJing Cosmic Ray Laboratory
(Tibet) located 4300 m a.s.l. The performance of RPCs in detecting Extensive
Air Showers was studied. Efficiency and time resolution measurements at the
pressure and temperature conditions typical of high mountain laboratories, are
reported.Comment: 16 pages, 10 figures, submitted to Nucl. Instr. Met
Systematic comparison of plasma EBV DNA, anti-EBV antibodies and miRNA levels for early detection and prognosis of nasopharyngeal carcinoma
Nasopharyngeal carcinoma (NPC) is originated from the epithelial cells of nasopharynx, Epstein-Barr virus (EBV)-associated and has the highest incidence and mortality rates in Southeast Asia. Late presentation is a common issue and early detection could be the key to reduce the disease burden. Sensitivity of plasma EBV DNA, an established NPC biomarker, for Stage I NPC is controversial. Most newly reported NPC biomarkers have neither been externally validated nor compared to the established ones. This causes difficulty in planning for cost-effective early detection strategies. Our study systematically evaluated six established and four new biomarkers in NPC cases, population controls and hospital controls. We showed that BamHI-W 76 bp remains the most sensitive plasma biomarker, with 96.7% (29/30), 96.7% (58/60) and 97.4% (226/232) sensitivity to detect Stage I, early stage and all NPC, respectively. Its specificity was 94.2% (113/120) against population controls and 90.4% (113/125) against hospital controls. Diagnostic accuracy of BamHI-W 121 bp and ebv-miR-BART7-3p were validated. Hsa-miR-29a-3p and hsa-miR-103a-3p were not, possibly due to lower number of advanced stage NPC cases included in this subset. Decision tree modeling suggested that combination of BamHI-W 76 bp and VCA IgA or EA IgG may increase the specificity or sensitivity to detect NPC. EBNA1 99 bp could identify NPC patients with poor prognosis in early and advanced stage NPC. Our findings provided evidence for improvement in NPC screening strategies, covering considerations of opportunistic screening, combining biomarkers to increase sensitivity or specificity and testing biomarkers from single sampled specimen to avoid logistic problems of resampling
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