arXiv subjects

Jian Wang

Publications and source records attributed to Jian Wang.

At least 937 records · Page 52Linked to original sources

arXiv2019

Violation of the Kluberg-Stern--Zuber theorem in SCET

A classic result, originally due to Kluberg-Stern and Zuber, states that operators that vanish by the classical equation of motion (eom) do not mix into "physical" operators. Here we show that and explain why this result does not hold in soft-collinear effective theory (SCET) for the renormalization of power-suppressed operators. We calculate the non-vanishing mixing of eom operators for the simplest case of $N$-jet operators with a single collinear field in every direction. The result implies that---for the computation of the anomalous dimension but not for on-shell matrix elements---there exists a preferred set of fields that must be used to reproduce the infrared singularities of QCD scattering amplitudes. We identify these fields and explain their relation to the gauge-invariant SCET Lagrangian. Further checks reveal another generic property of SCET beyond leading power, which will be relevant to resummation at the next-to-leading logarithmic level, the divergence of convolution integrals with the hard matching coefficients. We propose an operator solution that allows to consistently renormalize such divergences.

hep-ph↗

arXiv2019

Fractional-order Backpropagation Neural Networks: Modified Fractional-order Steepest Descent Method for Family of Backpropagation Neural Networks

This paper offers a novel mathematical approach, the modified Fractional-order Steepest Descent Method (FSDM) for training BackPropagation Neural Networks (BPNNs); this differs from the majority of the previous approaches and as such. A promising mathematical method, fractional calculus, has the potential to assume a prominent role in the applications of neural networks and cybernetics because of its inherent strengths such as long-term memory, nonlocality, and weak singularity. Therefore, to improve the optimization performance of classic first-order BPNNs, in this paper we study whether it could be possible to modified FSDM and generalize classic first-order BPNNs to modified FSDM based Fractional-order Backpropagation Neural Networks (FBPNNs). Motivated by this inspiration, this paper proposes a state-of-the-art application of fractional calculus to implement a modified FSDM based FBPNN whose reverse incremental search is in the negative directions of the approximate fractional-order partial derivatives of the square error. At first, the theoretical concept of a modified FSDM based FBPNN is described mathematically. Then, the mathematical proof of the fractional-order global optimal convergence, an assumption of the structure, and the fractional-order multi-scale global optimization of a modified FSDM based FBPNN are analysed in detail. Finally, we perform comparative experiments and compare a modified FSDM based FBPNN with a classic first-order BPNN, i.e., an example function approximation, fractional-order multi-scale global optimization, and two comparative performances with real data. The more efficient optimal searching capability of the fractional-order multi-scale global optimization of a modified FSDM based FBPNN to determine the global optimal solution is the major advantage being superior to a classic first-order BPNN.

cs.NE↗

arXiv2019

Region-Manipulated Fusion Networks for Pancreatitis Recognition

This work first attempts to automatically recognize pancreatitis on CT scan images. However, different form the traditional object recognition, such pancreatitis recognition is challenging due to the fine-grained and non-rigid appearance variability of the local diseased regions. To this end, we propose a customized Region-Manipulated Fusion Networks (RMFN) to capture the key characteristics of local lesion for pancreatitis recognition. Specifically, to effectively highlight the imperceptible lesion regions, a novel region-manipulated scheme in RMFN is proposed to force the lesion regions while weaken the non-lesion regions by ceaselessly aggregating the multi-scale local information onto feature maps. The proposed scheme can be flexibly equipped into the existing neural networks, such as AlexNet and VGG. To evaluate the performance of the propose method, a real CT image database about pancreatitis is collected from hospitals \footnote{The database is available later}. And experimental results on such database well demonstrate the effectiveness of the proposed method for pancreatitis recognition.

eess.IV↗

arXiv2019

Momentum-space threshold resummation in $tW$ production at the LHC

We calculate the soft-gluon corrections for $tW$ production to all orders. The soft limit is defined in the pair invariant mass or one particle inclusive kinematic schemes. We find that at NLO the contribution of the soft-gluon effect dominates in the total cross section or the differential distributions. After resumming the soft-gluon effect to all orders using the renormalization group equation, we find that the NLO+NNLL results increase the NLO cross sections by $12\%\sim 17\%$ depending on the scheme and the collider energy. Our results are in agreement with the measurements at the 8 and 13 TeV LHC. We also provide predictions for the total cross section at the 14 TeV LHC.

hep-ph↗

arXiv2019

Constraints on generalized Eddington-inspired Born-Infeld branes

The Palatini $f(|\hatΩ|)$ gravity is a generalized theory of the Eddington-inspired Born-Infeld gravity, where $Ω_{~N}^{K}\equivδ_{~N}^{K}+bg^{KL}R_{LN}(Γ)$ is an auxiliary tensor constructed with the spacetime metric $g$ and independent connection $Γ$. In this paper, we study $f(|\hatΩ|)$ theory with $f(|\hatΩ|)=|\hatΩ|^{\frac{1}{2}+n}$ in the thick brane scenario and give some constraints on the brane model. We finally found an analytic solution of the thick brane generated by a single scalar field. The behavior of the negative energy density denotes the localization of the thick brane at the origin of the extra dimension. In our braneworld, the warp factor is divergent at the boundary of the extra dimension while the brane system is asymptotically anti$-$de Sitter. It is shown that the tensor perturbation of the brane is stable and the massless graviton is localized on the thick brane. Therefore, the effective Einstein-Hilbert action on the brane can be rebuilt in the low-energy approximation. According to the recent test of the gravitational inverse-square law, we give some constraints on the $f(|\hatΩ|)$ brane.

hep-th↗

arXiv2019

Simply-connected open 3-manifolds with slow decay of positive scalar curvature

The goal of this paper is to investigate the topological structure of open simply-connected 3-manifolds whose scalar curvature has a slow decay at infinity. In particular, we show that the Whitehead manifold does not admit a complete metric, whose scalar curvature decays slowly, and in fact that any contractible complete 3-manifolds with such a metric is homeomorphic to $\mathbb{R}^{3}$. Furthermore, using this result, we prove that any open simply-connected 3-manifold $M$ with $π_{2}(M)=\mathbb{Z}$ and a complete metric as above, is homeomorphic to $\mathbb{S}^{2}\times \mathbb{R}$.

math.DG↗

arXiv2019

When the kernel of a complete hereditary cotorsion pair is the additive closure of a tilting module

In this paper, we study when the kernel of a complete hereditary cotorsion pair is the additive closure of a tilting module. Applications go in three directions. The first is to characterize when the little finitistic dimension is finite. The second is to obtain equivalent formulations for a Wakamatsu tilting module to be a tilting module. The third is to give some new characterizations of Gorenstein rings.

math.RA↗

arXiv2019

Predicting the Mumble of Wireless Channel with Sequence-to-Sequence Models

Accurate prediction of fading channel in the upcoming transmission frame is essential to realize adaptive transmission for transmitters, and receivers with the ability of channel prediction can also save some computations of channel estimation. However, due to the rapid channel variation and channel estimation error, reliable prediction is hard to realize. In this situation, an appropriate channel model should be selected, which can cover both the statistical model and small scale fading of channel, this reminds us the natural languages, which also have statistical word frequency and specific sentences. Accordingly, in this paper, we take wireless channel model as a language model, and the time-varying channel as talking in this language, while the realistic noisy estimated channel can be compared with mumbling. Furthermore, in order to utilize as much as possible the information a channel coefficient takes, we discard the conventional two features of absolute value and phase, replacing with hundreds of features which will be learned by our channel model, to do this, we use a vocabulary to map a complex channel coefficient into an ID, which is represented by a vector of real numbers. Recurrent neural networks technique is used as its good balance between memorization and generalization, moreover, we creatively introduce sequence-to-sequence (seq2seq) models in time series channel prediction, which can translates past channel into future channel. The results show that realistic channel prediction with superior performance relative to channel estimation is attainable.

eess.SP↗

arXiv2019

Disorder induced multifractal superconductivity in monolayer niobium dichalcogenides

The interplay between disorder and superconductivity is a subtle and fascinating phenomenon in quantum many body physics. The conventional superconductors are insensitive to dilute nonmagnetic impurities, known as the Anderson's theorem. Destruction of superconductivity and even superconductor-insulator transitions occur in the regime of strong disorder. Hence disorder-enhanced superconductivity is rare and has only been observed in some alloys or granular states. Because of the entanglement of various effects, the mechanism of enhancement is still under debate. Here we report well-controlled disorder effect in the recently discovered monolayer NbSe$_2$ superconductor. The superconducting transition temperatures of NbSe$_2$ monolayers are substantially increased by disorder. Realistic theoretical modeling shows that the unusual enhancement possibly arises from the multifractality of electron wave functions. This work provides the first experimental evidence of the multifractal superconducting state.

cond-mat.supr-con↗

arXiv2019

Re-Identification Supervised Texture Generation

The estimation of 3D human body pose and shape from a single image has been extensively studied in recent years. However, the texture generation problem has not been fully discussed. In this paper, we propose an end-to-end learning strategy to generate textures of human bodies under the supervision of person re-identification. We render the synthetic images with textures extracted from the inputs and maximize the similarity between the rendered and input images by using the re-identification network as the perceptual metrics. Experiment results on pedestrian images show that our model can generate the texture from a single image and demonstrate that our textures are of higher quality than those generated by other available methods. Furthermore, we extend the application scope to other categories and explore the possible utilization of our generated textures.

cs.CV↗

arXiv2019

Multi-dimensional entanglement transport through single-mode fibre

The global quantum network requires the distribution of entangled states over long distances, with significant advances already demonstrated using entangled polarisation states, reaching approximately 1200 km in free space and 100 km in optical fibre. Packing more information into each photon requires Hilbert spaces with higher dimensionality, for example, that of spatial modes of light. However spatial mode entanglement transport requires custom multimode fibre and is limited by decoherence induced mode coupling. Here we transport multi-dimensional entangled states down conventional single-mode fibre (SMF). We achieve this by entangling the spin-orbit degrees of freedom of a bi-photon pair, passing the polarisation (spin) photon down the SMF while accessing multi-dimensional orbital angular momentum (orbital) subspaces with the other. We show high fidelity hybrid entanglement preservation down 250 m of SMF across multiple 2x2 dimensions, demonstrating quantum key distribution protocols, quantum state tomographies and quantum erasers. This work offers an alternative approach to spatial mode entanglement transport that facilitates deployment in legacy networks across conventional fibre.

quant-ph↗

arXiv2019

Distinguishing Local and non-Local Demagnetization in Ferromagnetic FePt Nanoparticles

Time-resolved coherent X-ray diffraction is used to measure the spatially resolved magnetization structure within FePt nanoparticles during laser-induced ultrafast demagnetization. The momentum-dependent X-ray magnetic diffraction shows that demagnetization proceeds at different rates at different X-ray momentum transfer. We show that the observed momentum-dependent scattering has the signature of inhomogeneous demagnetization within the nanoparticles, with the demagnetization proceeding more rapidly at the boundary of the nanoparticle. A shell region of reduced magnetization forms and moves inwards at a supermagnonic velocity. Spin-transport calculations show that the shell formation is driven by superdiffusive spin flux mainly leaving the nanoparticle into the surrounding carbon. Quantifying this non-local contribution to the demagnetization allows us to separate it from the local demagnetization.

cond-mat.mtrl-sci↗

arXiv2019

Leading-logarithmic threshold resummation of the Drell-Yan process at next-to-leading power

We resum the leading logarithms $α_s^n \ln^{2 n-1}(1-z)$, $n=1,2,\ldots$ near the kinematic threshold $z=Q^2/\hat{s}\to 1$ of the Drell-Yan process at next-to-leading power in the expansion in $(1-z)$. The derivation of this result employs soft-collinear effective theory in position space and the anomalous dimensions of subleading-power soft functions, which are computed. Expansion of the resummed result leads to the leading logarithms at fixed loop order, in agreement with exact results at NLO and NNLO and predictions from the physical evolution kernel at N$^3$LO and N$^4$LO, and to new results at the five-loop order and beyond.

hep-ph↗

arXiv2019

Master integrals of a planar double-box family for top-quark pair production

We calculate analytically the master integrals of a planar double-box family for top-quark pair production using the method of differential equations. With a proper choice of the bases, the differential equations can be transformed to the $d$-log form. The square roots of the kinematic variables in the differential equations can be rationalized by defining two dimensionless variables. We find that all the boundary conditions can be fully fixed either by simple integrals or regularity conditions at some special kinematic points. The analytic results for thirty-three master integrals at general kinematics are all expressed in terms of multiple polylogarithms up to transcendental weight four.

hep-ph↗

arXiv2019

Design of a general scientific CCD simulation and test system

In this paper, we introduce a general scientific CCD simulation and test system which can meet the test requirements of different types of CCD chips from E2V company, such as measuring different signals output from modules of a CCD controller including power supply, fan, temperature control module, crystal oscillator, shutter and clock-bias generator. Furthermore, the video signal of the CCD detector can be simulated and superimposed with random noise to verify the performance of the video sampling circuit of the CCD controller. The simulation and test system was successful used for the CCD controller which was designed for E2V CCD47-20 detector.

physics.ins-det↗

arXiv2019

Design of remote control software of near infrared Sky Brightness Monitor in Antarctica

The Near-infrared Sky Brightness Monitor (NIRBM) aims to measure the middle infrared sky background in Antarctica. The NIRBM mainly consists of an InGaAs detector, a chopper, a reflector, a cooler and a black body. The reflector can rotate to scan the sky with a field of view ranging from 0° to 180°. Electromechanical control and weak signal readout functions are accomplished by the same circuit, whose core chip is a STM32F407VG microcontroller. Considering the environment is harsh for humans in Antarctica, a multi-level remote control software system is designed and implemented. A set of EPICS IOCs are developed to control each hardware module independently via serial port communication with the STM32 microcontroller. The tornado web framework and PyEpics are introduced as a combination where PyEpics is used to monitor or change the EPICS Process Variables, functioning as a client for the EPICS framework. Tornado is responsible for the specific operation process of inter-device collaboration, and expose a set of interfaces to users to make calls. Considering the high delay and low bandwidth of the network environment, the tornado back-end is designed as a master-and-agent architecture to improve domestic user experience. The master node is deployed in Antarctic while multiple agent nodes can be deployed domestic. The master and agent nodes communicate with each other through the WebSocket protocol to exchange latest information so that bandwidth is saved. The GUI is implemented in the form of single-page application based on the Vue framework which communicates with tornado through WebSocket and AJAX requests. The web page integrates device control, data curve drawing, alarm display, auto observation and other functions together.

astro-ph.IM↗

arXiv2019

Spectra of the Dissipative Spin Chain

This paper generalizes the (0+1)-dimensional spin-boson problem to the corresponding (1+1)-dimensional version. Monte Carlo simulation is used to find the phase diagram and imaginary time correlation function. The real frequency spectrum is recovered by the newly developed Páde regression analytic continuation method. We find that, as dissipation strength $α$ is increased, the sharp quasi-particle spectrum is broadened and the peak frequency is lower. According to the behavior of the low frequency spectrum, we classify the dynamical phase into three different regions: weakly damped, linear $k$-edge, and strongly damped.

cond-mat.str-el↗

arXiv2019

Bonding and oxidation protection of Ti${_2}$AlC and Cr${_2}$AlC for a Ni-based Superalloy

Alumina forming, oxidation and thermal shock resistant MAX phases are of a high interest for high temperature applications. Herein we report, on bonding and resulting interactions between a Ni-based superalloy, NSA, and two alumina forming MAX phases. The diffusion couples Cr${_2}$AlC/Inconel-718/Ti${_2}$AlC were assembled and heated to 1000 or 1100°C in a vacuum hot press under loads corresponding to stresses of either 2 MPa or 20 MPa. The resulting interfaces were examined using X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Good bonding between Cr${_2}$AlC and NSA was achieved after hot pressing at 1000°C and a contact pressure of only 2 MPa; in the case of Ti${_2}$AlC a higher temperature (1100°C) and pressure (20 MPa) were needed. In both cases, a diffusion bond was realized with no evidence of interfacial damage or cracking after cooling to room temperature. Twenty thermal cycles from room temperature to 1000°C showed that Ti${_2}$AlC is a poor oxidation barrier for Inconel-718. However, in the case of Cr${_2}$AlC no cracks, delamination nor surface degradation were observed, suggesting that this material could be used to protect Inconel-718 from oxidation.

cond-mat.mtrl-sci↗