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Although its ubiquitous emergence in nature and variety of systems, turbulence possesses spatio-temporal chaotic, intermittent fluctuations, and makes it impossible to be precisely predicted. Persistent attempts for almost a century have been devoted to capture the invariant laws and hidden deeply universality out of the vast disorder and chaotic nature of turbulence. The celebrated Kolmogorov -5/3 law is robust, but not comprehensive to describe the diverse turbulences, especially in the turbulence driven by external volume forces, e.g. thermal convection, electrokinetic turbulence and etc. Here, we reveal that the fluxes of kinetic energy and scalar variance must be highly coupled to establish a universal conservation law and consequently we successfully unify a much diversity of scaling laws. As an example, in a microfluidic electrokinetic turbulence, additional scaling of -5/3, -9/5 and -7/3 are experimentally found in the power spectra of concentration. With this proposed model, a full quad-cascade picture is eventually complete to unify the various scaling laws for the most complicated physical problem of turbulence.

The interference phenomenon of light is a common but most important effect in physics. In this article, we compare and analyse the interference effects of both coherent and incoherent light; in particular, the interference of spatially incoherent light sources is described. Thermal light and a two-photon entangled source may both be regarded as incoherent sources which can generate similar second-order interference effects, but their underlying physics is quite different. First-order interference can be realized with both spatially coherent and incoherent sources in the same well-designed experimental setup, but exhibit different interference patterns; their different interference mechanisms will also be clarified., Comment: 46 pages,31 figures

Electroosmotic flow (EOF) exists widely at the solid-liquid interface in the presence of external electric field. However, the EOF driven by an alternating current (AC) electric field in diverse chemical environments was far from being well understood due to limited experimental investigations. In this investigation, through the high-resolution laser-induced fluorescent photobleaching anemometer (LIFPA), the transient velocity according to the AC EOF on the electric double layer (EDL) far from the electrodes has been experimentally characterized, by means of time series and power spectra. With analyzing the transient velocity, the transition of AC EOF from linear to nonlinear behavior is observed in a broad parameter space, e.g. mean flow velocity, the frequency and intensity of the AC electric field, and the pH value of the bulk fluid. To take all these parameters into account, an electro-inertial velocity has been applied as the characteristic velocity, instead of the commonly applied Helmholtz-Smouluchowski velocity. Then, the transitional electric field intensity $E_{A,C}$ and the corresponding dimensionless parameter $Z_{nlc}$ are systematically studied. A power-law relationship between the linear term coefficient $Z_l$ and $Z_{nlc}$ has been established, with the scaling exponents determined by the pH value of the electrolyte solution. We hope the current investigation can provide a deeper understanding of the transition of AC EOF and the instantaneous response of EOFs in other forms. It also provides a simple model to understand the coupling between electric field and fluid flow, in both linear and nonlinear status.

The crucial zeroth-order light due to the pixelation effect of spatial light modulator (SLM) has been a serious issue in the field of light modulation, especially in applications with a high numerical aperture optical system. In this investigation, we report that by properly adjusting the high-level and low-level pixel voltages of an SLM, the zeroth-order light caused by the pixelation effect of SLM can be significantly eliminated. The method is further validated in an inverted fluorescence microscope. The experimental results show that the zeroth-order light can be inhibited up to 91.3%, accompanied by an improvement of the modulation efficiency from 77.5% to 92.6%., In this version, the mechanism underlined has been corrected. Accompanied, Figure 1 has been replaced

The sustainable development and utilization of sandy areas in arid and semiarid regions is of strategic importance to ensure both food and ecological security. The unique geographical environment of these areas and uncontrolled exploitation by farmers lead to large amounts of fragmented cropland. Despite government management, the quantity and distribution of these fragmented croplands is unknown, and accurate identification of the region’s fragmented croplands can provide data to support the sustainable use of sandy areas. We propose a method for identifying fragmented cropland based on scale transformation. Small-scale fragmented cropland is approximately represented at larger scales, so we apply small-scale high-resolution remote sensing images to identify features and obtain information at a large scale, i.e., the ratio of fragmented cropland area. By correcting the cropland areas identified from low-resolution remote sensing images and using them as the basis for the resulting calculation, more accurate identification can be 1 at a large scale. In this study, this method was applied based on remote sensing images with 0.54 and 30 m resolutions that were acquired during the same period, using Horqin Zuoyihou Banner as the study area. The results showed that (1) there was 13,637.08 hm2 of fragmented cropland in Horqin Zuoyihou Banner due to precipitation and terrain topography, mainly in the central and western regions and 2) identification at the sample point scale and plot scale were positively correlated in area and showed a consistent distribution. Therefore, accurate and efficient identification of fragmented cropland can be achieved through scale transformation.

Aspect-based sentiment analysis (ABSA) is a fine-grained sentiment analysis task designed to predict the sentiment polarity of each aspect term in a text. Recent research mainly uses neural networks to model text and utilizes attention mechanisms to interact for associate aspect terms and context to obtain more effective feature representation. However, the general attention mechanism is easy to lose the original information. Besides, in the multi-aspect text, the sentiment information of other aspect terms interferes with the sentiment analysis of the current aspect term likely. In this paper, we propose two models named RA-CNN and RAO-CNN for ABSA tasks. In RA-CNN, we apply CNN to model the aspect term and utilize a specially designed residual attention mechanism to interact with the text. Based on the RA-CNN, RAO-CNN adds other aspect terms module, which can reduce interference of sentiment information related to other aspect terms in the multi-aspect text. To verify the proposed models’ effectiveness, we conduct a large number of experiments and comparisons on seven public datasets. Experimental results show that our proposed models are useful and achieve state-of-the-art results.

Aspect-based sentiment analysis can predict the sentiment polarity of specific aspect terms in the text. Compared to general sentiment analysis, it extracts more useful information and analyzes the sentiment more accurately in the comment text. Many previous approaches use long short-term memory networks with attention mechanisms to directly learn aspect-specific representations and model comment text. However, these methods always ignore the importance of the aspect terms position and interactive information between the aspect terms and other words. To address these issues, we propose an improved model based on convolutional neural networks. First, a novel relative position encode layer can integrate the relative position information of specific aspect terms validly in a text. Second, by using the aspect attention mechanism, the semantic relationship between aspect terms and words in the text is fully considered. To verify the effectiveness of the proposed models, we conduct a large number of experiments and comparisons on seven public datasets. The experimental results show that this model outperforms to other state-of-the-art methods.

Crushed rock revetment (CRR) has been widely implemented to mitigate the geothermal disturbance from the embankment construction and global warming. The cooling effect and air convective mode of the traditional CRR (TCRR) and a new designed solar−shading CRR (SSCRR) were comparatively studied based on a developed and verified heat and mass transfer model. The results indicate that TCRR used as a protecting measure cannot eliminate the geothermal disturbance in warm permafrost regions, but can preserve the permafrost foundation in cold permafrost regions, while SSCRR can further cool the permafrost foundation. If TCRR is added to reinforce a 10 years operated general embankment, it can only grudgingly keep the thermal disturbed state for about 35 years and 45 years in warm and cold permafrost regions, respectively. SSCRR, by contrast, can refrigerate the operation–disturbed permafrost foundation. Wind−forced dominated convection for TCRR in warm season dissipates the ‘cold energy’ accumulated in cold season, however, synthetic reaction for SSCRR with a longer and higher efficiency cooling process in cold season and better heat insulating effect in warm season conducts a superior cooling effect. These results provide a basis for the optimization of cold energy utilization systems for the embankments in the degenerating permafrost regions.

In this paper, a new generalized step-up multilevel DC-AC converter is proposed, which is suitable for applications with low-voltage input sources such as photovoltaic power generation and electric vehicles. This inverter can achieve a high voltage gain by controlling the series-parallel conversion of DC power supply and capacitors. Only one DC voltage source and a few power devices are employed. The maximum output voltage and the number of output levels can be further increased through the switched-capacitor unit's extension and the submodule cascaded extension. Moreover, the capacitor voltages are self-balanced without complicated voltage control circuits. The complementary operating mechanism between each pair of switches simplifies the modulation algorithm. The inductive-load ability is fully taken into account in the proposed inverter. Additionally, a remarkable characteristic of the inverter is that the charging and discharging states among different capacitors are synchronous, which reduces the voltage ripple of the frontend capacitors. The circuit structure, the working principle, the modulation strategy, the capacitors and losses analysis are presented in detail. Afterwards, the advantages of the proposed inverter are analyzed by comparing with other recently proposed inverters. Finally, the steady-state and dynamic performance of the proposed inverter is verified and validated by simulation and experiment. 1

Perception plays an important role in reliable decision-making for autonomous vehicles. Over the last ten years, huge advances have been made in the field of perception. However, perception in extreme weather conditions is still a difficult problem, especially in rainy weather conditions. In order to improve the detection effect of road targets in rainy environments, we analyze the physical characteristics of the rain layer and propose a deraining convolutional neural network structure. Based on this network structure, we design an ablation experiment and experiment results show that our method can effectively improve the accuracy of object detection in rainy conditions.

Quantum imagers have won accolades for their quantum characteristics and fruitful applications. Ghost imaging exhibited nonlocality with quantum-entangled photons from the parametric down-conversion process, and later with thermal-light sources. Single-pixel imaging retrieved high-quality images with compressive sensing and singular valued decomposition algorithms. Single-photon sensitive apparatus were conducive to first-photon imaging, light-in-flight imaging, photon-efficient imaging, and super-remote imaging. Photon-limited imaging was investigated in low-light-level ghost imaging and fast first-photon ghost imaging. Here in the single-pixel imager scheme, we present zero-photon imaging in which high-quality negative images are reconstructed by correlating the zero-photon measurements and the modulation signals. Also, images are reconstructed with few-photon-state measurements. By comparison, the image quality in ZPI is much higher. This technique may be of significant benefit to rapid pattern recognition and remote sensing., 7 pages, 4 figures, two columns

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Supplemental Document

Because social networks have become a vital part of people’s lives, cyberbullying becomes the most common risk encountered by young people on social networking platforms and raised serious concerns in society. Over the past few decades, most existing work on cyberbullying has focused on text analysis. Yet, the cyberbullying develops into multi-objective, multi-channel, and multi-form. Traditional text analysis methods cannot satisfy the diversity of bullying data in social networks. To deal with the new type of cyberbullying, we propose a multi-modal detection framework that takes into multi-modal information(e.g., image, video, comments, time) on social networks. Specifically, we not only extract textual features but also use the hierarchical attention networks to capture the session feature in social networks and encode several media information(e.g., video, image). Based on these features, we model the multi-modal cyberbullying detection framework to solve the new form of cyberbullying. Experimental analysis on two real-world datasets shows that our framework outperforms several existing state-of-the-art models.

A large area nanopore array with controllable consistency has been fabricated by direct laser writing (DLW) technique with ultralow one-photon absorption (LOPA). In this technique, a doughnut-shape beam generated by 532 nm continuous-wave laser through a vortex phase plate was focused into the thin film of SU8 photoresist by a high numerical aperture objective. The low absorption of the photoresist at the excitation wavelength allowed controllable fabricating structures with sub-diffraction-limit feature size and high aspect ratio. With point-by-point scanning fabrication, nanopore array with the pore's internal diameter, about ten percent of incident laser wavelength, far smaller than Abbe's diffraction limit was achieved. The influences of the exposure intensity and exposure time on the fabricated nanopore size and shape were also investigated by scanning electron microscope (SEM).

The uniformity of the pore size and the morphology of nano-porous anodic alumina (nano-PAA) can be improved by a pore-widening process. The evolution of the pore diameter and the morphology was investigated in real time. Phosphoric acid solution (3wt%) was used as the etchant to chemically enlarge the pores of a nano-PAA prepared with oxalic acid. It is found that the pore-widening is carrying out simultaneously both on top-view and cross-section. From the top-view analysis, the pore diameter gradually enlarges with the increasing of etching time. However, such enlarging rate varies with the multilayer structure of the pore wall. From the cross-section analysis, the pores walls of a multilayered amorphous compound are etched in a stage-by-stage mode until almost everything is etched away. The pore-widening procedure on the upper portion is completed earlier respect to the lower portion, after some time the pore-widening becomes uniform along the axial direction. If the etching is maintained, hexagonal pore walls will be destroyed and split into ultrahigh aspect ratio nanowires due to the etching anisotropy, and finally completely dissolved. Combining analyses in the depth direction with stereoscopic 3D imaging the results clarify the pore-widening mechanism in 3D nano-PAA.

In classical optics, Young's double-slit experiment with colored coherent light gives rise to individual interference fringes for each light frequency, referring to single-photon interference. However, two-photon double-slit interference has been widely studied only for wavelength-degenerate biphoton, known as subwavelength quantum lithography. In this work, we report double-slit interference experiments with two-color biphoton. Different from the degenerate case, the experimental results depend on the measurement methods. From a two-axis coincidence measurement pattern we can extract complete interference information about two colors. The conceptual model provides an intuitional picture of the in-phase and out-of-phase photon correlations and a complete quantum understanding about the which-path information of two colored photons., Comment: 13 pages, 6 figures

This paper studies the properties of a kind of portable ultra-bright microfocus x-ray source with the Monte-Carlo method in detail. The new x-ray source consists of an electron-emission system, an electrostatic focusing system and a metal target. A crystal Lanthanum Hexaboride cathode, a Wehnelt grid and an extracted electrode compose the triode electrode electron-gun system. Two equal radius cylinder electrodes form the focusing system. The key factors determining the focus properties of the electron beam such as the ratio Dw/H, grid bias Vg, and the properties of the extracted electrode are numerically studied. The calculated results reveal that when Dw/H, Vg, the length of the extracted electrode, and the distance between the grid and the extracted electrode equals 5, –0.6 kV, 10 mm, and 8 mm respectively, the electron beam focal spot can be concentrated down to 9 μm in radius and a reasonable focal length about 72.5 mm can be achieved, at the same time, the cathode emission currents can be as high as 30 mA.

This paper reports that when an intense extraordinary-polarized laser beam illuminates a photorefractive BaTiO3 crystal, the dynamic beam fanning light is formed to be a thermal-like light source with a long correlation time and wide spectral bandwidth. The experimental results of the first- and second-order double-slit interference with such photorefractive fanning light source, can be understood with the theoretical simulation in terms of Hanbury-Brown and Twiss effect.

We propose a special two-photon state which is completely transparent in a 50/50 beam splitter. This effect is caused by the destructive two-photon interference and shows the signature of photon entanglement. We find that the symmetry of the two-photon spectrum plays the key role for the properties of two-photon interference.

We analyse a dynamical swapping of the quantum state in coupled harmonic oscillators. The result can be applied to the interaction of a single-mode field with atomic ensemble in the weak field case. Similar to the case of electromagnetic induced transparency (EIT), a dynamic polariton is formed. Therefore, the quantum state of the field can be completely mapped on to the atomic medium, and vice versa. Using this dynamical swapping and the adiabatic transfer in the EIT between the field and atomic ensemble, we propose a scheme in which both the quantum and the coherent information can be transferred from one field to another.

The spatial-temporal correlations of resonant fluorescence from a single two-level atom is studied based on the investigation of different photocurrent correlations after homodyning the fluorescence with a local oscillator. It is found that the nonclassical features of the measured field is position-dependent on the detection plane.

We apply the quantum regression theorem and the input-output relation of the single-ended cavity to the linearized systems, and formulate the optical quantum nondemolition (QND) criteria. In an application, we discuss squeezing and QND nature for a crossed Kerr dispersive model.

We evaluate the effectiveness of the quantum nondemolition (QND) measurement scheme in an effective two-level atomic configuration by using the input–output formalism and the quantum regression theorem. The QND capability can be promoted greatly as the cavity detuning is swept towards the bistability threshold.

We discuss the phase dynamics in the system of a set of nonlinear coupled oscillators. We find a direct and simple geometric method to observe the geometric phase for this system, and it provides a possibility for the experimental measurements.

The sub-diffraction-limit spatially structured light patterns have attracted more and more attention for their important applications in many frontier scientific fields. The present paper aims at developing sub-diffraction-limit spatially structured beam patterns which might have great potential to improve the light performance in fields such as super resolution imagery, optical tweezer, micro/nano lithography, etc. Here, a variety of spatially structured beam patterns are obtained by the phase modulation of polarized beams and studied in detail experimentally and numerically. Firstly, a new kind of phase plate, which combines the merits of circular and vortex 2 phase plates, is proposed based on the wave front design; it is composed of two spiral-shaped phase plates with their phases changing from 0 to 2 and - to , respectively. Later, the phase plate is applied to the circularly polarized Gaussian beam modulation in a high NA system. By combining a self-made circular with a commercial vortex 2 phase plate, the designed new phase plate is implemented in the experiment. The morphology of the spatially structured light pattern, which is generated on the focal plane, is observed by a CCD camera in the experiment. The beam pattern presents a donut shape on the focal plane, while the dimension of the donut-shaped pattern becomes smaller as the imaging plane axially deviates from the focal plane. It is found that the beam patterns captured in experiment highly consist with the numerical simulation results carried out by the vectorial diffraction integral theory. It can be deduced that the spatially structured beam is capillary-shaped. Meanwhile, at the two ends of the capillary-shaped beam, the inner diameter is smaller than the diffraction limitation. Furthermore, the structured beam pattern presents a spatial voxel distribution with center and axis symmetry. Finally, the characteristics of the spatially structured beam patterns, which are generated by modulating circular, linear, radial and azimuthal polarized beams with the new designed phase plate, are analyzed and discussed in detail. It is found that for circular, linear, radial and azimuthal polarization, the full widths at half maximum (FWHMs) of the minimum dark spots in the horizontal direction are 0.31, 0.32, 0.24 and 0.36, respectively. On the optical axis, the FWHMs of the dark spots created by linearly, radially and azimuthally polarized light, are 0.8, 0.78 and 0.76 , respectively, and no axial intensity is found with circularly polarized beam incidence.

We report the first experimental observation of quantum holographic imaging with entangled photon pairs, generated in a spontaneous parametric down-conversion process. The signal photons play both roles of "object wave" and "reference wave" in holography but are recorded by a point detector providing only encoding information, while the idler photons travel freely and are locally manipulated with spatial resolution. The holographic image is formed by the two-photon correlation measurement, although both the signal and idler beams are incoherent. According to the detection regime of the signal photons, we analyze three types of quantum holography schemes: point detection, coherent detection and bucket detection, which can correspond to classical holography using a point source, a plane-wave coherent source and a spatially incoherent source, respectively. Our experiment demonstrates that the two-photon holography in the point detection regime is equivalent to the one-photon holography using a point source. Physically, the quantum holography experiment verifies that a pair of non-commutable physical quantities, the amplitude and phase components of the field operator, can be nonlocally measured through two-photon entanglement., Comment: 10 pages, 4 figures

The interaction between two single-stranded DNA (ssDNA) molecules as pairing to a double-stranded DNA (dsDNA) molecule is studied by the reflectometric interference spectroscopy (RIFS) technology. A nano-porous anode alumina membrane coated an Au layer is employed as the sensor substrate. The results indicate that when there are mismatched nucleotide bases, the effective optical thicknesses (OTeff ) have obvious difference, and the changes of OTeff are connected with the sensor layer thickness and the effective refractive index. It is also demonstrated that the RIFS technique can be used to precisely detect the ssDNA molecules with individual base mismatched as pairing to dsDNA.

We report an experimental observation of quantum Airy disk diffraction pattern using an entangled two-photon source. In contrast to the previous quantum lithography experiments where the subwavelength diffraction patterns were observed in the far field limit, we perform the Fraunhofer diffraction experiment with a convex lens. The experimental result shows that the two-photon Airy disk is provided with the super-resolution spot, which surpasses the classical diffraction limit. In particular, the spot size can be well controlled by the focal length, which adapted to optical super-focusing. Our experiment can promote potential application of quantum lithography., 4 pages, 2figures

We investigate numerically the dynamical bifurcations that occur in detuned degenerate four-wave mixing as the pump intensity is varied. We find several types of gluing bifurcations and symmetry-breaking bifurcations. A sequence of symmetric-breaking and gluing bifurcations leads to Lorenz-like chaos.

The global dynamical behavior of a model describing the formation of one-dimensional transverse patterns in a laser has been investigated. Solutions of the equation for the complex electric field are compared to those of a reduced phase equation, the laser Kuramoto-Sivashinsky equation, which should be a good approximation for small detuning. The numerical results show strong evidence of the leading role of the dynamics of the phase of the field in the formation of transverse patterns in a laser with small detuning

The authors calculate analytically the squeezing spectra of the signal and pump fields in a degenerate optical parametric oscillator for arbitrary values of the detuning parameters. For this purpose they use the recently introduced semi-classical method as well as the standard quantum approach.

Complementarity is usually considered as a phenomenon of microscopic systems. In this paper we report an experimental observation of complementarity in the correlated double-slit interference with a pseudothermal light source. The thermal light beam is divided into test and reference beams which are correlated with each other. The double-slit is set in the test arm, and the interference pattern can be observed in the intensity correlation between the two arms. The experimental results show that the disappearance of interference fringe depends on whether which-path information is gained through the reference arm. The experiment therefore witnesses the complementarity occurring in a macroscopic system., 6 pages, 4 figures

We perform a nonlocal double-slit interference experiment with pseudothermal light. The experimental result exhibits a typical double-slit interference fringe in the intensity correlation measurement, in agreement with the theoretical analysis by means of the property of the second-order spatial correlation of field., Comment: 2 pages, 2 figures

We show that a thermal light random in transverse direction can perform subwavelength double slit interference in a joint-intensity measurement. This is the classical version of quantum lithography, and it can be explained with the correlation of rays instead of the entanglement of photons., 4 pages, 2 figures

We discuss the geometrical optics of coincidence imaging for two kinds of spatial correlations which are related to a classical thermal light source and a two-photon quantum entangled state., Comment: 4 pages, 5 figures

We show the experimental observation of the classical sub-wavelength double-slit interference with a pseudo-thermal light source. The experimental results are in agreement with the recent theoretical prediction shown in quant-ph/0404078 (to be appeared in Phys. Rev. A)., Comment: 4 pages, 6 figures

We analyze a double $��$ atomic configuration interacting with two signal beams and two control beams. Because of the quantum interference between the two $��$ channels, the four fields are phase-matched in electromagnetically induced transparency. Our numerical simulation shows that this system is able to manipulate synchronous optical signals, such as generation of optical twin signals, data correction, signal transfer and amplification in the atomic storage., 5 pages, 7 figures