Search

We investigate the “inverted” solitons in spin-orbit-coupled Bose-Einstein condensate with one-dimensional spatially periodic Zeeman field. Soliton existence depends on the exact invert for the condensate components in the spatially periodic Zeeman field. And the position and the total pseudomagnetization density of the solitons can be controlled by the spatially periodic Zeeman field. Simulated results show that the inverted solitons can be stable for the interatomic attractive interactions.

In this paper, the liquefaction of a Bulianta coal, from China Shenhua Group, was carried out in a hydrogen donor solvent, tetralin, or a non-hydrogen donor solvent, 1-methylnaphthalene, with or without catalyst to clarify the mechanism of hydrogen transfer. And roles of solvent and a nano-size iron catalyst from Shenhua Group in the heating-up stage of DCL were also investigated by using mixed solvent of decalin, phenanthrene, pyrene or fluoranthene and tetralin. The results show that tetralin inhibits the reaction of coal macromolecule to oil and the transfer of H2. The major transfer approach of H2 may be directly from H2 to coal rather than via the hydrogen donor solvents in the presence of the nano-sized iron catalyst. In the heating-up stage of DCL, the major role of solvent is to provide activated hydrogen for coal. High dissolving capability of the liquefaction solvent that has high enough hydrogen donor capacity is beneficial for improving liquefaction performance. The dominant function of the catalyst is to promote the activation of H2, which can improve coal liquefaction performance in the heating-up stage of DCL.

To study wing-body rock, various tests were used for the canard-configuration models in the wind tunnel, including free rolling, disturbance on free rolling, static moment measurements, dynamic derivative measurements, smoke wire method and particle image velocimetry. The models also have a chine forebody, strake wings, main wings and a vertical tail. In the tests, the canard deflection angles are 0° and 20° relative to the axis of the body. First, the roll angle time histories were obtained by free rolling motion and disturbed motion; the results demonstrate that both canard-configuration models have nonzero mean roll angles. In particular, the existence of the other larger nonzero mean roll angles on the same side is a curious aspect at the critical pitch angle, such as at θ = 37° for the model with canard deflection of 20°. Next, static moment tests and dynamic derivative tests demonstrate that although the roll angle time histories are non-limit cycle motions, they are irregularly self-excited oscillation under the influence of multi-vortex structures. Finally, the constituent parts of structures over wing bodies and the flow mechanism of abruptly jumping from an equilibrium roll angle to the other on the same roll side were revealed by the smoke wire and particle image velocimetry measurements.

Multi-field coupling simulation method based on the physical principles is used to simulate the discharge characteristics of nanosecond pulsed plasma synthetic jet actuator. Considering the effect of the energy transferring for air, the flow characteristics of nanosecond pulsed plasma synthetic jet actuator are simulated. The elastic heating sources and ion joule heating sources are the two main sources of energy. Through the collisions, the energy of ions is transferred to the neutral gas quickly. The flow characteristics of a series of blast waves and the synthetic jet which erupt from the plasma synthetic jet (PSJ) actuator are simulated. The blast wave not only promotes outward, but also accelerates the gas mixing the inhaled gas from the outside cavity with the residual gas inside the cavity. The performances of PSJ actuator fluctuate in the first three incentive cycles and become stable after that.

We report on the existence and stability of fundamental and out-of-phase dipole gap solitons in parity-time (PT)-symmetric mixed linear-nonlinear optical lattices with a fourth-order diffraction. These solitons exist in the semi-infinite gap. For fundamental gap solitons, they can bifurcate from the higher edge of the first Bloch band, solitons are stable in the low power region. For dipole gap solitons, they cannot bifurcate from the higher edge of the first Bloch band, they can stably exist in the moderate power region. The coupling constant of the fourth-order diffraction can influence the stability of these gap solitons.

The surface dielectric barrier discharge plasma actuator driven by nanosecond pulses is recognized as an effective fluid actuator for flow separation control. The operation condition of nanosecond dielectric barrier discharge actuators for separated flow control still requires further study, particularly prioritizing the improvement of the effectiveness and reducing energy consumption in flow separation control implementation. In this study, experiments are conducted using a two-dimensional NASA SC(2)-0712 airfoil in a wind tunnel with a Reynolds number of 0.5 × 106 (25 m/s). The pressure measurement experiments show that the location of actuators affects the efficiency of separation control. Particle image velocimetry results indicate that the most efficient location of the actuator is upstream of the separation point and near the original point of the separated shear layer. Meanwhile, the particle image velocimetry results show the vorticity attaches to the airfoil wall after discharge, which suggests that the reattachment is due to the generation of large-scale vortices. These present structures result in the mixing of the shear layer with the main flow thereby delaying separation and reattaching a separated flow. This study shows the most efficient location related to the separation point. Furthermore, it indicates the reattachment of flow is attributed to the motion of vortexes coherent structure.

The modern high performance air vehicles are required to have extreme maneuverability, which includes the ability of controlled maneuvers at high angle of attack. However, the nonlinear and unsteady aerodynamic phenomena, such as flow separation, vortices interaction, and vortices breaking down, will occur during the flight at high angle of attack, which could induce the uncommanded motions for the air vehicles. For the high maneuverable and agile air missile, the nonlinear roll motions would occur at the high angle of attack. The present work is focused on the self-induced nonlinear roll motion for a missile configuration and discusses the influence of the strake wings on the roll motion according to the results from free-to-roll test and PIV measurement using the models assembled with different strake wings at α = 60°. The free-to-roll results show that the model with whole strake wings (baseline), the model assembled with three strake wings (Case A) and the model assembled with two opposite strake wings (Case C) experience the spinning, while the model assembled with two adjacent strake wings (Case B), the model assembled with one strake wing (Case D) and the model with no strake wing (Case E) trim or slightly vibrate at a certain “×” rolling angle, which mean that the rolling stability can be improved by dismantling certain strake wings. The flow field results from PIV measurement show that the leeward asymmetric vortices are induced by the windward strake wings. The vortices would interact the strake wings and induce crossflow on the downstream fins to degrade the rolling stability of the model. This could be the main reason for the self-induced roll motion of the model at α = 60°.

Solvent plays two very important roles in coal liquefaction: (1) Physically, it serves as a medium for coal transport and heat transfer, and (2) chemically, it serves as an important source of transferable hydrogen (hydrogen donor) and hydrogen shuttle between hydrogen and coal. In this work, eight types of non-hydrogen-donor solvents, namely, decalin, 1-methylnaphthalene, naphthalene, fluorene, anthracene, phenanthrene, pyrene, and fluoranthene, were examined in combination with the hydrogen-donor solvent tetralin in the liquefaction of Bulianta coal to clarify the interactions between the hydrogen-donor and non-hydrogen-donor solvents and the mechanism of hydrogen transfer. In the absence of a catalyst, the mixed solvents of tetralin with phenanthrene, pyrene, and fluoranthene showed favorable effects on coal conversion and oil yield compared with pure tetralin, regardless of whether the reactions were conducted in a H2 or N2 atmosphere. The reactions of non-hydrogen-donor solvents with tetralin showed ...

A cruciform-finned slender body can excite a limit-cycle rolling oscillation at high angles of attack. To suppress the unwanted motions, flow control approaches should be employed if the aerodynamic control surfaces lose control efficiency at high angles of attack. As a promising technology, the ns-dielectric barrier discharge plasma actuator has been successfully used in high-speed and high-Reynolds-number flow control applications. The present work employs a π-type ns-dielectric barrier discharge plasma actuator and vortex generators to suppress self-excited rolling oscillation at α = 50°. The free-to-roll tests show that the plasma actuator ignited at F+ ∼ 1.5 and that the vortex generators can suppress rolling oscillation. The flow patterns from particle image velocimetry measurement at different cross-sections and rolling angles suggest that the vorticity decrease of the leeward vortices may be the control mechanism for the plasma actuator. For the vortex generators, evident modification of the flow field structure can be observed due to the vortices generated from the vortex generators, which decreases the rolling moment induced by the asymmetry vortices to suppress the self-excited rolling oscillation.

We report on the properties of fundamental defect matter-wave gap solitons in spin–orbit-coupled Bose–Einstein condensates in one-dimensional Zeeman lattices with attractive nonlinearity. One component of these solitons is a real even function, and the other is an imaginary odd function. When the defect is repulsive, these solitons can be stable in the semi-infinite, first, and second gaps. Increasing the strength of spin–orbit coupling, stable defect gap-stripe solitons in the semi-infinite and first gaps are found. However, for an attractive defect, the solitons only stably exist in the semi-infinite gap and cannot be close to the lower edge of the first Bloch band.

The method of symmetrical spanwise blowing was used to suppress the wing-body rock of a typical canard-configuration model in free-to-roll tests. The experimental results showed that the rock was successfully suppressed by symmetrical spanwise blowing when the pitch angle was between thirty degrees and thirty-four degrees. However, this kind of blowing failed to suppress the non-commanded motion once pitch angle exceeded thirty-four degrees. To analyze the mechanism under this phenomenon, surface-pressure measurements and PIV tests were carried out. The reason for the successful suppression was inferred as the success of the delaying of windward vortex breakdown at a small sideslip angle, while the failed results at larger pitch angles were due to the fact that the blowing cannot delay the windward breakdown anymore under very small sideslip.

Attitude control of a conventional aircraft usually depends on its rudder surface, which reduces the aircraft’s stealth abilities and makes it heavier. To improve aerodynamic performance an...

The bioaccumulation and the main source of total Hg (THg) and methylmercury (MMHg) in the deposit-feeding polychaete Neanthes japonica collected in Jinzhou Bay, China, were investigated. Compared with the historical data, THg bioaccumulation in polychaetes collected in sediment of Jinzhou Bay was distinctly higher due to higher sediment THg concentration, but MMHg bioaccumulation was significantly lower. THg accumulation in polychaetes mainly derived from its accumulation in sediment. However, MMHg bioaccumulation in polychaetes did not correlate with Hg concentration in sediment. Besides sediment ingestion, MMHg accumulation in polychaetes may partially source from the process of in vivo transformation. The in vivo Hg methylation may take place in polychaetes, according to the excellent correlation between MMHg concentration and THg and inorganic Hg concentration in polychaetes. The biochemical characters in polychaete body, the oxidation-reduction environment and the microbial activity in polychaete gut may be beneficial to in vivo Hg methylation.

Controlled orientation and alignment of rod‐shaped plasmonic nanoparticles are of great interest for many applications. Herein, it is demonstrated that the nonlinear optical response of gold nanorod suspensions is dynamically controlled by electric field‐induced orientation. Merely by switching incident light polarization, the longitudinal and transverse surface plasmon resonance (SPR) absorption peaks are modulated with opposite trends, and the resulting optical nonlinearity is revealed from self‐trapping of plasmonic resonant solitons. Moreover, even with a very low concentration of fluorescent molecules, a significant increase in the fluorescent signal is observed with a transmittance‐type volume detection scheme. Such an enhancement is attributed to a combined action of optical force‐induced nonlinearity and electric field‐induced nanorod orientation, as explained by the theoretical analyses. Herein, new possibilities for engineering nonlinear plasmonic soft matter and detecting low‐concentration (yet a large total number of moleculesas needed) fluorescent samples are brought out.

This study explores the effects of wingtip connection on decreasing energy consumption and increasing flight endurance for solar aircraft. The Oswald efficiency factor, induced drag coefficient and power consumption are derived as the models of the number of wingtip connected aircraft. As the energy margin model is related to the number of connected solar aircraft, a flight endurance margin model is proposed to evaluate the advantages of wingtip connection quantitatively. With the numerical method developed, researches on the energy and flight endurance performance for a given example wingtip-connected solar aircraft are performed. Moreover, the impacts of solar cell efficiency, flight date and latitude on the advantages of wingtip connection for solar aircraft are explored. The results suggest that the wingtip connection design enables solar aircraft to decrease induced drag coefficient, increase flight endurance and range effectively when the aircraft is only powered by battery. The wingtip connection design is more effective to increase the flight endurance and improve the maximum perpetual flight latitude with more connected solar aircrafts and higher solar cell efficiency, especially in the flight condition with high solar elevation angle and more daylight hours. However, as the number of connected solar aircraft increases, the effect of one more connected aircraft on these advantages decreases because the effect of wingtip connection on decreasing induced drag coefficient decreases with increasing aspect ratio.

In order to further study the inner characteristics of the plasma synthetic jet actuator (PSJA) which consists of a cavity, two electrodes and a lid with orifice, a two-dimensional numerical simulation is carried out with SST k-ω turbulence model. The evolutions of the flow parameters inside the cavity with a single pulse, such as pressure, density, temperature and velocity, are analyzed in detail. The oscillation mechanisms of the flow parameters at the orifice of the cavity is also investigated. To study the effects of geometric factors on the performance of the PSJA, five widths and heights of the cavities are considered. The results suggest that the base frequencies are inversely proportional to the width and height of the cavity respectively. The proportional constant is equal to the sound speed. Besides, shortening the width or height of the cavity can obtain a faster peak velocity of the jet. The peak of the jet velocity occurs earlier with a shorter height of the cavity.

Next-generation aircraft and missile are required to have extreme maneuverability, which should maintain stability at high angle of attack. However, the unsteady flow field surrounding the air vehicle would affect the aerodynamics loads and induce unwanted nonlinear motions, of which the rolling motions are usually generated. In order to investigate the unsteady rolling characteristics of a cruciform-finned slender body, the free-to-roll and force measurement tests including particle image velocimetry measurement have been conducted comprehensively. Different types of rolling motion, trimming at equilibrium positions, self-excited rolling oscillation, and self-excited spinning are observed during the free-to-roll experiment depending on the different angles of attack. The force measurement results show that the rolling motions are related to both the static and dynamic stabilities of the rolling moment at balance points. The stabilities of the rolling moment would change as the angle of attack for the model increases. At last, the flow field results from particle image velocimetry measurement indicate that the unsteady rolling motions may be induced by the interaction between the asymmetry vortices and strake wings, fins.

The basic dynamic characteristic of a nanosecond (NS) pulse discharge actuator in still air is investigated, which introduces viscid and inviscid effects to the flow, namely, heated air and pressure waves, respectively. The efficacy of a dielectric barrier discharge plasma actuator driven by a nanosecond pulse for active flow separation control is investigated experimentally on a NASA SC(2)-0712 aerofoil at Re = 0.5 × 10 6 (25 m/s). The pressure distribution on the aerofoil surface is measured, and the result indicates that the separation is well controlled at a high angle of attack. The PIV test result shows that the forcing frequency selectively affects the flow over the aerofoil, and a higher forcing frequency has a better influence on the leading edge shear layer. Schlieren imaging experiments at Re = 0.1 × 10 6 (5 m/s) show that the main disturbance factor for the nanosecond pulse plasma actuator is the heating effect, which changes the local temperature and density and induces several vortex structures. The vortex structures entrain the outer high-momentum fluid into the shear layer, thereby strengthening the mixing of the shear layer with the main flow and delaying separation or even reattaching a separated flow. The research reveals the major disturbance factor introduced by NS discharge applied to flow separation control. Furthermore, the spatiotemporal disturbance process induced by the pulse discharge is investigated.

Controlling the morphology of nanostructured materials is critical for their use in technological applications including in sensing, electronics and energy harvesting. In this paper we investigate the reaction pathways involved and their dependence on reactant concentrations in the formation of ZnO nanomaterials on –COOH terminated self-assembled monolayers using a simple chemical bath deposition process which employs zinc acetate, which acts as the Zn source, and ethylenediamine, which acts as both the O source and a complexing agent for Zn2 +. At a deposition temperature of 318 K (45 °C) our data shows that the concentration of Zn2 + as well as the deposition bath pH, which is controlled by the ethylenediamine concentration, is critical in determining the ZnO morphology. Above 0.01 M zinc acetate at low bath pH (~ 7.7–8.5), nanorods and nanorockets are observed to form. The nanorods exhibit a clear interface in the middle indicating that they are composed of two crystals. At lower zinc acetate concentrations over a wide pH range (~ 8.0–10.5) nanoflowers form. The nanorockets and nanoflowers grow via a modified La Mer mechanism in which there are multiple nucleation and crystallization steps. The initial nuclei are sphelurites (nanoflowers) or nanocrystallites (nanorockets). Since the reagent concentrations limit the reaction, for these initial precursor crystallites to increase in size, it is required dissolution and re-precipitation must occur. Thus at later times nanorockets or nanoflowers develop.

Fatigue is one of the most common yet complicated failures that can cause damage to mechanical structures. Structural adhesively bonded joints are not exempt from this deleterious phenomenon and have to be assessed under vibration loads. In this work, fatigue characteristics of single-lap joints (SLJ) made of steel and carbon fibre reinforced plastic (CFRP) laminates under vibration loads are primarily investigated by experiments. The aim of this work is to analyze the changes in the ultimate load of the SLJ under vibration loads. The experimental results showed that SLJ will face cohesive failure after the uniaxial tensile loading test. In addition to the increase of vibration cycles, the ultimate load and failure displacement gradually decrease. In order to model the adhesive between joint components and simulate the damage propagation, a new traction–separation law called the embedded process zone (EPZ) and a damage factor are introduced and developed within the framework of cohesive zone Model...

Proteins are often an important component of many bulk surfaces in biological and environmental systems that are coated with complex organic compounds that may also interact with NPs. We investigated the deposition of bare hematite NPs onto various proteins adsorbed on either negatively- or positively-charged bottom surfaces. Bovine serum albumin (BSA), lysozyme, and ubiquitin were used as model proteins and total protein extracts from two bacterial strains, Escherichia coli and Pseudomonas fluorescens, were used as complex protein mixtures. The NP deposition extents and rates were shown to be significantly different depending on the protein. The maximum difference observed was 8.6 ± 3.2 fold between E. coli and P. fluorescens proteins adsorbed onto positively-charged planar surfaces. These differences in NP deposition characteristics are attributed to the differences in physicochemical features of the topmost surface of the protein layer, such as the amino acid profiles, surface charge, and hydrophilicity. Such differences were likely driven by differences in species, orientation, and conformation of the adsorbed proteins. In particular, NP deposition was driven by various combinations of electrostatic and hydrophobic interactions. This study indicates that NP deposition onto surface-adsorbed proteins is an important mechanism in protein–NP interactions and that the deposition is strongly dependent on both the conformation and chemical characteristics of the adsorbed protein layer.

A new dynamic test mechanism has been developed in the unsteady low-speed wind tunnel at Nanjing University of Aeronautics and Astronautics to enhance the abilities of experiments in the unsteady flow cases. The structure of the new test mechanism is described in detail in this paper and the equations used to control the performance of test model’s motions are also listed here. Then a wing-body model was tested in the new test system for the first time, including the forced oscillation tests and free-to-roll test at high angle of attack region. The test results are also discussed.

We investigate the nonlocal gray solitons in parity-time (PT)-symmetric potentials with spatially modulated nonlinearity. If the nonlinear modulated function (nonlinear potential) is real, the coefficient of the function can control the grayness and the existence domain of these gray solitons. Especially, if the coefficient of the nonlinear modulated function is below a threshold, the gray solitons will be changed into anti-dark solitons. The effects of the degree of the nonlocality and the imaginary part of the PT-symmetric potentials on the grayness and the existence of the gray solitons are also discussed. If the nonlinear modulated function is also PT symmetric, the imaginary part of the function will obviously affect the existence and stability of the nonlocal gray solitons.

Uncommanded self-induced roll oscillations cause significant challenges in flight control and are ubiquitous in high-attack-angle flights in the flying-wing configuration. Spanwise blowing slots were designed in this article to suppress these roll oscillations with nonzero mean angles of a 53° swept flying-wing model. Three flow control strategies were proposed and studied successively. The open-loop symmetric blowing successfully suppressed oscillations below the nominal angle of attack of 24° before losing its effectiveness. Subsequently, adaptive continuous blowing using the proportion-integral-differential algorithm was performed with symmetric pre-blowing to eliminate the ineffective region with a small blowing coefficient. Using this strategy, roll oscillations under all tested nominal angles of attack were successfully addressed as the nonzero trim angles were eliminated and the oscillations were suppressed. However, the air consumption needed to maintain the model balance was too large, which necessitated the development of pulsed blowing. Static force measurements showed that the blowing-induced rolling moment had a linear relationship with the duty cycle of blowing. The results from the particle-image-velocimetry tests revealed that the mechanism of the linear relationship was the increased duration of coherent vortices over a period at longer duty cycles. Based on the static experimental results, the model was stabilized via proportion-integral-differential adaptive blowing, which utilized the duty cycle as the control variable. Compared to the second strategy, the last one reduced the required mean blowing momentum coefficient by two orders of magnitude while maintaining a great control effect.

In this study, we investigated the effects of surface sliding discharge of a dielectric barrier discharge (SL-DBD) plasma actuator on the boundary layer flow using the time-resolved particle image velocimetry (PIV) technique. According to the PIV measurements, the peak-shaped mean jet flow is induced by the SL-DBD plasma actuator in quiescent air. Under the freestream of U∞ = 6 m/s on the flat plate, the results show that the streamwise velocity fluctuation induced by SL-DBD plasma is increased pronouncedly at the downstream of the actuator. Meanwhile, the mean flow velocity increases obviously in the downstream of the actuator. The instantaneous results show the formation of the vorticity at the bottom of the boundary layer after the plasma excitation. In addition, the vorticity has the behavior to lift up, possibly because of the induced peak-shaped jet.

With the prosperity of the Internet of Things (IoT) industry environment, the variety and quantity of IoT devices have grown rapidly. IoT devices have been widely used in smart homes, smart wear, smart manufacturing, smart cars, smart medical care, and many other life-related fields. With it, security vulnerabilities of IoT devices are emerging endlessly. The proliferation of security vulnerabilities will bring severe risks to users&rsquo, privacy and property. This paper first describes the research background, including IoT architecture, device components, and attack surfaces. We review state-of-the-art research on IoT device vulnerability discovery, detection, mitigation, and other related works. Then, we point out the current challenges and opportunities by evaluation. Finally, we forecast and discuss the research directions on vulnerability analysis techniques of IoT devices.

We propose a design of a center high mounted stop lamp (CHMSL) based on Fresnel lens. The Fresnel lens is divided into four layers. The first layer collimates the beam of Light Emitting Diode (LED) along the direction perpendicular to optical axis; The second layer makes the output light uniformly distributed; The third layer collimates the beam along the optical axis direction; The fourth layer scatters the collimating light to make the last light distribution meet the relevant regulations. The simulation and test results show that the efficient of this CHMSL is 38.3 % and the uniformity is about 92.4 %. This CHMSL is practical and can applicable to vehicle lighting.

Selenium (Se) is a necessary trace element for humans and animals, and Se fertilization is an efficient way to increase Se concentration in the edible parts of crops, thus enhance the beneficiary effects of Se in human and animal health. Due to the similarity of physical and chemical properties between phosphate () and selenite (), phosphorus (P) supply often significantly impacts the absorption of Se in plants, but little is known about how P supply influences the subcellular distribution and chemical forms of Se. In this study, the effects of P supply on subcellular distribution and chemical forms of Se in winter wheat were investigated in a hydroponic trial with medium Se level (0.1 mg Se L-1). P was applied with three concentrations (0.31, 3.1, and 31 mg P L-1) in the experiment. The results showed that increasing P supply significantly decreased the concentration and accumulation of Se in the roots, stems, and leaves of winter wheat. An increase in P supply significantly inhibited Se accumulation in the root cell wall, but enhanced Se distribution in the organelles and soluble fraction of root cells. These findings suggest that increased P supply inhibited the root-to-shoot transport of Se. An increase in P supply enhanced Se accumulation in the cell wall of plant stems (both apical and axillary stem) and cell organelles of plants leaves, but inhibited Se distribution in the soluble fraction of stems and leaves. This suggests that P supply enhances Se transportation across the cell membrane in shoots of winter wheat. In addition, increased P supply also altered the chemical forms of Se in tissues of winter wheat. These findings will help in understanding of the regulation grain Se accumulation and provide a practical way to enhance Se intake for humans inform Se-enriched grains.

In this paper, we investigate the popular neural word embedding method word2vec as a source of evidence in short text similarity calculation, which has been applied to intention classification of user queries in our intelligent customer service system — Alime. For avoiding information loss on sentence-level vector representation, we design a Word Similarity Maximization (WSM) method, which utilize word-level embedding vectors to directly calculate query similarity. Experimental results on a dataset from real daily user query data from Alime system show WSM can better detect query-intention relation than baseline methods.

Word sense disambiguation (WSD) plays an important role in natural language processing, such as information retrieval, text summarization, question answering, machine translation, etc. Abbreviation disambiguation is an important sub-domain of WSD, and in this paper we try to construct a co-occurrence knowledge base for realizing fast abbreviation disambiguation, since speed is essential in applications such as question answering and machine translation. In our proposed method, named entities in context of abbreviations are essential for this disambiguation task, and the final experimental results show that our method can effectively realize the mentioned aim.

Fast diffusion of information makes microblogging an efficient platform for seeking information, and the most convenient way for a user to get useful information is following others and in real time the updates of the followed users will be presented automatically. Deciding to follow or not to follow a user is usually based on this user's tweet content, because users usually try to find friends who post information relevant to their interests. Since reading through all tweets of a user is very time-consuming, we need to design a convenient user summarization form. In this paper, we design a model for summarizing users with their most representative tweets. The experimental results on Sina-weibo, one of the most popular microblogging sites in China, show our model can get a better performance than baseline methods.

Selenium (Se) is a necessary trace element for humans and animals, and Se fertilization is an efficient way to increase Se concentration in the edible parts of crops, thus enhance the beneficiary effects of Se in human and animal health. Due to the similarity of physical and chemical properties between phosphate () and selenite (), phosphorus (P) supply often significantly impacts the absorption of Se in plants, but little is known about how P supply influences the subcellular distribution and chemical forms of Se. In this study, the effects of P supply on subcellular distribution and chemical forms of Se in winter wheat were investigated in a hydroponic trial with medium Se level (0.1 mg Se L-1). P was applied with three concentrations (0.31, 3.1, and 31 mg P L-1) in the experiment. The results showed that increasing P supply significantly decreased the concentration and accumulation of Se in the roots, stems, and leaves of winter wheat. An increase in P supply significantly inhibited Se accumulation in the root cell wall, but enhanced Se distribution in the organelles and soluble fraction of root cells. These findings suggest that increased P supply inhibited the root-to-shoot transport of Se. An increase in P supply enhanced Se accumulation in the cell wall of plant stems (both apical and axillary stem) and cell organelles of plants leaves, but inhibited Se distribution in the soluble fraction of stems and leaves. This suggests that P supply enhances Se transportation across the cell membrane in shoots of winter wheat. In addition, increased P supply also altered the chemical forms of Se in tissues of winter wheat. These findings will help in understanding of the regulation grain Se accumulation and provide a practical way to enhance Se intake for humans inform Se-enriched grains.

A common capping agent for gold nanorods, Cetyl trimethylammonium bromide (CTAB), is particularly problematic for biological studies because of its cytotoxicity. Several procedures have been developed to remove the CTAB from the surface of the gold nanorods, but most are lengthy, involving many steps, and use expensive reagents. Here, we present a simple, one-pot method for the complete removal of CTAB from the surface of gold nanorods, so that particles can be more effectively utilized in biological in vivo studies. The procedure involves first adding sodium borohydride to remove the CTAB, quickly followed by a replacement ligand, such as mercaptoundecanoic acid (MUA). Both the CTAB removal and MUA replacement were monitored by FTIR, surface enhanced Raman spectroscopy (SERS) and X-Ray Photoelectron Spectroscopy (XPS) and compared to commercially available citrate-capped gold nanorods. The procedure presented herein is shown to be as effective at removing CTAB and replacing it with MUA as commercially available gold nanorod samples.

The room temperature atomic layer-like deposition (ALLD) of ZnO using diethylzinc (DEZ) and water precursors has been investigated on −COOH, −OH, and −CH3 terminated self-assembled monolayers. The detailed reaction pathways of ZnO ALLD on −COOH and −OH terminated SAMs are different. As expected on −OH terminated SAMs, the DEZ reacts with the hydroxyl group. However, on −COOH terminated SAMs DEZ reacts with both the carbonyl and hydroxyl bonds present and can lead to the formation of a ketone rather than ZnO deposition. The growth rates on these SAMs are different; after the first ALLD cycle the measured growth rates are 3.0 ± 0.1 and 3.4 ± 0.2 A/cycle on −COOH and −OH terminated SAMs, respectively. XPS analyses show that the initial composition of the deposited layer on −COOH terminated SAMs is similar to Zn(OH)2. After five ALLD cycles the −COOH terminated SAM is completely covered, and XPS analyses indicate that the deposited film is composed of ZnO. In contrast on −OH terminated SAMs, the deposited fil...

We study the existence of discrete solitons in saturable nonlinearity media with parity-time symmetric lattices. We find that there exist two kinds of discrete solitons, they share the same parameters but different energy flows. The degree of saturable nonlinearity can influence the properties of such discrete solitons. Stable discrete solitons are found near the anti-continuum limit.

We report the fabrication of 2D ZnIn2S4 nanosheet/1D TiO2 nanorod heterojunction arrays by a facile hydrothermal process and their use as photoelectrodes in a photoelectrochemical (PEC) cell for high-performance solar water splitting. The morphology, microstructure, and phase of pristine TiO2 and 2D ZnIn2S4 nanosheet/1D TiO2 nanorod heterojunction arrays were characterized in detail. PEC measurements showed that 2D/1D heterojunction arrays offered enhanced photocurrent density (3 times higher than that of pristine TiO2), negatively shifted onset potential from 0.05 to -0.53 V, and high light on/off cycle stability. Electrochemical impedance investigation attested to a significant improvement of the interface electron transfer kinetics in this heterojunction, thus facilitating electron-hole separation, transfer, and collection, which resulted in enhanced PEC properties.

An array PSJA is tested in this paper by using high-speed phase-lock schlieren system. The characteristic of the transient flow field is studied. The experiment shows that a series of high-speed blast waves spreads outward after discharge. These blast waves, attenuated to the local sound speed, form a wavefront, which continues to influence the flow field. Due to the interaction between each blast wave and the squeeze from previous blast waves, the subsequent blast waves' impact range is limited and form “jet-like” phenomenon. A little later, there comes a high-speed jet to continuous influence the flow field.

We investigate numerically the existence and stability of discrete multipole dark solitons in saturable nonlinearity media with parity-time ( $\mathcal{PT}$ ) symmetric lattices. The dipole and triple solitons share the same existence domain associated with the propagation constant, gain-loss coefficient and the degree of saturable nonlinearity. However, the solitons stably propagate in a different area of the aforementioned three parameters. The beam power monotonously increases with the increase of propagation constant and the saturable degree, but gently decreases with the gain-loss coefficient. Moreover, the power of the triple solitons is higher than that of dipole solitons under the same conditions.

We investigate numerically the interaction between two finite Airy-Gaussian (AiG) beams in different media with the defected photonic lattices in one transverse dimension. We discuss that the beams with different intensities and phases launch into the different lattice structures but accelerate in opposite directions. During interactions, the interference fringe, breathers, and soliton pairs are observed. In the linear media, the initial deflection direction of the accelerated beams is changed by adjusting the phase shift and the beam interval. For a certain lattice period, the periodic interference fringe can form. A constructive or destructive interference can vary with the defect depth and phase shift. While the nonlinearity is introduced, the breathers is generated. Especially in the self-defocusing media, the appropriate AiG beam amplitude and lattice depth may lead to the formation of soliton pairs, On the contrary, the interaction of two Gaussian beams is diffraction.

We investigate numerically that a finite Airy-Gaussian (AiG) beam varies its trajectory and shape in the defected photonic lattices. The propagation properties and beam self-bending are controlled with modulation depth and period of the photonic lattices, positive and negative defects, beam distribution factor and nonlinearity change. For positive defects, the pseudo-period oscillation and localization of the AiG beam may be formed under a certain condition, while the beam is diffused for negative defects. Moreover, the solitons may appear during the propagation process when the self-focusing nonlinearity is introduced., 15 pages, 8 figures

We embed a helical lattice into a portion of a bulk photorefractive medium to form a synthetic structure and numerically investigate the nonlinear transmission of a probe vortex beam in the structure. Numerical demonstrations confirm that the structure can stabilize multisoliton states in the form of nonrotating and nonexpanding necklacelike solitons. Lattice structure and the amplitude, width, and topological charge of the probe vortex beam can influence the structure of necklacelike solitons. Interestingly, an increase in beam intensity may lead to multiplication of the number of bright “spots.”

Sideslip-induced asymmetrical vortices are critical to the performance of canard-configuration aircraft. In this paper, a canard-configuration model was found to roll around a nonzero trim angle in a free-to-roll experiment, indicating a loss of lateral static stability. This loss was also evidenced by the positive slope of the rolling-moment versus sideslip curve. To reveal the underlying mechanism of this phenomenon, we focused on sideslip effects, taking surface-pressure measurements and conducting PIV (particle image velocimetry) tests. At the attack angle of 16°, sideslip causes inward extension of the windward low-pressure area on the main wings, which leads to a decrease in rolling moment. The inferred cause is the inward movement of the windward reattachment point. At the attack angle of 35°, complex multi-vortex structures were analyzed using PIV for three forms of the model: with all components; without canard; with neither canard nor strake. The effects of sideslip on vortex flow at high attack angle were then studied. As sideslip angle changed from -1° to 1°, sideslip promotes the breakdown of windward vortices, causing a sharp decrease in windward suction. Subsequently, as sideslip angle changed from 1° to 4°, the backward movement of the breakdown point and an increase in strength of vortices are observed on the leeward side, which coincides with an increase in both leeward suction and the rolling moment. As the sideslip angle continues to increase, the inboard vortex on the leeward side rises and becomes weak, which leads to a decrease in leeward suction, and hence, the recovery of lateral static stability. Moreover, the coiling of leeward vortices weakens under sideslip.Sideslip-induced asymmetrical vortices are critical to the performance of canard-configuration aircraft. In this paper, a canard-configuration model was found to roll around a nonzero trim angle in a free-to-roll experiment, indicating a loss of lateral static stability. This loss was also evidenced by the positive slope of the rolling-moment versus sideslip curve. To reveal the underlying mechanism of this phenomenon, we focused on sideslip effects, taking surface-pressure measurements and conducting PIV (particle image velocimetry) tests. At the attack angle of 16°, sideslip causes inward extension of the windward low-pressure area on the main wings, which leads to a decrease in rolling moment. The inferred cause is the inward movement of the windward reattachment point. At the attack angle of 35°, complex multi-vortex structures were analyzed using PIV for three forms of the model: with all components; without canard; with neither canard nor strake. The effects of sideslip on vortex flow at high attack...

Sliding discharge, as a new type of electrical discharge, is being gradually applied in plasma active flow control in recent years. In this work, the particle image velocimetry (PIV) experiments were conducted to investigate the airflow characteristics induced by the sliding discharge plasma actuator at varied voltage signals. The results show that the integral thrust produced by the negative alternating current (AC) power is stronger than normal AC power under the same voltage magnitude. The induced airflow direction changes along with the changing of two power voltage signals. Furthermore, the angle of the induced airflow is mainly linear with the loading voltage.

Detailed phase-lock schlieren measurement was conducted to study the physical evolution process of the structures inside the plasma synthetic jet actuator driven by a high voltage nanosecond pulse. One strong blast wave and heat source core are generated immediately after the arcing discharge. Within the cavity, as the blast wave is reflected by the cavity walls and interacts with the heat source core, the pressure of the gas inside the cavity is increased rapidly and a series of diffractive wave comes out from the orifice of the cavity, followed by a train of vortex rings and a high speed jet.

We propose a method for generation of tunable three-dimensional (3D) helical lattices with varying helix pitch. In order to change only the lattice helix pitch, a periodically varying phase along the propagation direction is added to the central beam - one of the interference beams for lattice construction. The phase periodicity determines the helix pitch, which can be reconfigured at ease. Furthermore, a helical lattice structure with an interface (domain wall) is also achieved by changing the phase structure of the lateral beams, leading to opposite rotating direction (helicity) on different sides of the interface. When a Gaussian beam is used to probe the bulk lattice, it can evolve into a spiral beam with its helicity varying in accordance with that of the lattice. Probing along the interface with two dipole-like optical beams leads to unusual propagation dynamics, depending on the phase and size of the two beams. This approach could be further explored for studies of nonlinear interface solitons and topological interface states. In addition, the helical lattices may find applications in dynamical multi-beam optical tweezers.

We investigate Airy-soliton interactions in self-defocusing media with PT potentials in one transverse dimension. We discuss different potentials in which the interacting beams with different phases are launched into the media at different separation distances. During interactions, there exist a primary collision region and a relaxation region accompanied by continuous interaction with the dispersed Airy tail. In the relaxation region, the beams exist soliton-like and breathers-like propagation. The beam width and mean power are influenced by initial separation, phase shift and modulation depth of PT potentials. Especially, the collision distance decreases with the spatial beam separation and the mean power possesses sinusoidal dependence on the phase shift., 16 pages, 5 figures