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The absorption properties of wave-absorbing coatings can easily fail; therefore, a layer of corrosion-resistant topcoat is often added to the surface to increase the service life of the absorbing coating. In this study, we compare the changes in samples without or with a topcoat, namely fluorinated polyurethane, at 25 °C with a NaCl solution and at 35 °C with a neutral salt spray. Morphological characterization and composition analysis show that the topcoat can indeed greatly improve the corrosion resistance of the samples, but the absorption of the coatings still decreases in a short time. The reasons for this are indicated by electrochemical impedance spectroscopy. For the samples without a topcoat, the corrosion of the wave-absorbing coatings results in the failure of wave absorption. For the samples with a topcoat, it is likely that the state of the interface between the topcoat and absorbing coatings leads to the decline of the resistance of the wave-absorbing coatings, causing them to fail quickly.

Peri-implantitis is a common reversible disease after tooth implantation, caused by a variety of pathogenic microorganisms. Based on non-surgical or surgical treatment principles, supplementation by local or systemic drugs might enhance treatment efficacy. Porphyromonas gingivalis (Pg) (ATCC 33277) and Prevotella intermedius (Pi) (ATCC 25611) were used as test strains. The effects of Pln 149 on the biofilm formation and growth of four periodontal pathogens were evaluated by RT-PCR, fluorescence microscopy, and scanning electron microscopy. The antibacterial mechanism was tested by the patch-clamp technique. The cytotoxicity of Pln 149 (125 µg/ml) to bone marrow stromal cell (BMSC) was assessed using an MTT assay. Pln 149 exhibited significant inhibitory effects on Pg and Pi (PLactobacillus plantarum 149 might be a promising option for managing peri-implantitis.

Light-driven polymerization, such as photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization, enables biological benign conditions and versatile functional polymer structure design, which is readily used in protein-polymer bioconjugates. However, conventional metalloporphyrinic homogeneous catalysts for PET-RAFT polymerization suffer from limited aqueous solubility and tedious purification. Here we demonstrate the design of PET-RAFT photocatalyst from the reticular assembled Zr-porphyrinic metal-organic frameworks (MOFs), along with a biomacromolecule-based chain transfer agent, as efficient bioconjugation tools in water. Our methodology offers manufacturing advantages on bioconjugates under mild conditions such that MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) and cytotoxicity assays have shown the preservation of the protein integrity, bioactivity, and high cell viability after PET-RAFT polymerization. We find that the fast kinetics are benefiting from the ultrahigh loading of metalloporphyrins in MOF-525-Zn. This heterogeneous catalyst also allows us to maintain living characteristics to incorporate myriads of monomers into block copolymers. Other advantages like easy postreaction purification, reusability, and high oxygen tolerance even in an open system are demonstrated. This study provides a tool of highly efficient heterogeneous photocatalysts for polymer-protein bioconjugation in aqueous media and paves the road for biological applications.

The linear and nonlinear evolutions and breakdown of the second modes in hypersonic boundary layers (HBLs) on a flared cone are investigated using Rayleigh-scattering flow visualization and fast-response pressure sensors. Based on two spatially separated pressure signals, cross-bicoherence analysis that permits the distinction of sum- and difference-interactions is utilized to identify the nonlinear interactions. In addition, the visualization temporal and spatial resolution allows fine flow features to be captured to provide additional flow information. Amplitude correlation technique is used to estimate the nonlinear energy transfer between the modes. Our results show that nonlinear interactions between the second mode and the low-frequency wave contribute to the growth of the low-frequency wave, and the difference interactions between the second mode and its first harmonic play a dominant role in modulating the waves in the overall transition process. Amplitude correlation analysis reveals that the spectral energy is nonlinearly transferred from the second mode into its first harmonic and into low-frequency wave, in agreement with the cross-bicoherence analysis. The amplitude modulation of the second mode caused by the difference interaction between the second mode and its first harmonic will reduce the propagation speed of the second mode. However, at the final breakdown stage, this difference interaction vanishes, and the second-mode propagation velocity recovers quickly. Since the frequency of the second mode keeps almost unchanged over the entire transition process, a higher propagation velocity will result in a larger wavelength, indicating an elongation and deformation of the second mode. Eventually, the difference interaction between the second mode and the low-frequency wave accompanying the energy transfer from the second mode to low-frequency waves leads to the final breakdown of the HBLs into a turbulent state.

The transient flow structures produced by a pulsed nanosecond plasma actuator and the mechanism by which they are generated are investigated experimentally and through simulations for the case of flow control on a non-slender delta wing. Phase-averaged particle image velocimetry reveals a phenomenon in which, after each discharge pulse, two sub-vortices are generated in sequence and move along the shear layer regardless of the angle of attack, and this is confirmed by hot-wire anemometry. However, at high actuation frequencies ( F+ = fc/ U∞ ≥ 6.435), this phenomenon of double sub-vortices is not observed, and only one sub-vortex is generated per period. The results of pressure measurements indicate that each sub-vortex gives rise to a distinct pressure fluctuation on the wing surface. Numerical simulations reveal a number of residual heats resulting from plasma thermal effects in the shear layer, each of which turns out to induce a corresponding sub-vortex. At low actuation frequencies ( F+ ≤ 4.29), there is a division of the initial residual heat into two independent residual heats and, hence, double sub-vortices per period, whereas at high actuation frequencies ( F+ ≥ 6.435), residual heats from two consecutive periods merge into one, resulting in just one sub-vortex per period, which provides an explanation for the experimentally observed flow behavior.

The plasma synthetic jet actuator (PSJA) has been proven to have potential for shock wave control in the supersonic/hypersonic flow. To evaluate the possibility for the PSJA applied in the hypersonic inlet under a Mach number greater than the design value and provide a deeper understanding of its control mechanism, the relevant two-dimensional numerical simulations are carried out. Based on the discussions about the numerical results, the effects are clear of the actuations generated by the PSJAs, including diffracted waves, synthetic jets, and discharged heat, on the oblique shock waves induced by the compression ramps and the aerodynamic performance of the hypersonic inlet. Concretely, the shapes of the oblique waves are changed by propagations of the diffracted waves, whose starting point moved due to the synthetic jets. A deceleration occurs near the surface of the hypersonic inlet caused by the movement of the discharged heat, leading to a thickener boundary layer. Furthermore, the incremental analysis about the total pressure recovery coefficient at the throat shows that the diffracted waves can increase the static pressure at the throat achieving a higher total pressure recovery coefficient, while the discharged heat makes the total pressure recovery coefficient drop due to a lower local Mach number at the throat. The effect of the discharged heat is more obvious than that of the diffracted waves.

Pulsed surface arc discharge (PSAD) is one of the essential techniques in flow control. In this paper, the effects of electrode configuration on heat transfer characteristics of PSAD and disturbance characteristics of PSAD on the flow field were investigated by thermal imaging technology and high-speed photography technology. By defining the curvature of curve (COC) of the electrode, we investigated the physical mechanism of the electrode configuration, affecting the PSAD disturbed flow field. The results show that the COC has the optimal solution COC opt. When COC ≤ COC opt, the smaller the COC, the more concentrated the PSAD disturbances to the flow field. When COC > COC opt, the electrode configuration will have an end point effect, resulting in a deviation between the theoretical COC and the real COC. The larger the COC, the stronger the end point effect, and the more concentrated the PSAD disturbances to the flow field. The COC affects the disturbance degree of PSAD to the flow field by distorting the electric field intensity distribution. The change in the electric field intensity causes the fluctuation frequency of the flow field to be inconsistent with the discharge frequency of the PSAD. The stronger the distortion degree of the electric field intensity, the stronger the high-frequency characteristics of the fluctuating frequency of the flow field, and the stronger the high-frequency characteristics of the flow mode of the flow field. In addition, we obtained the value range of COC opt within 0.5–0.7 through theoretical derivation and established a mathematical model of electrode structure's effect on the flow field's flow structure.

The complete flow structure and the composition of the flow structure generated by Pulsed Surface Arc Discharge in a Magnetic Field (M-PSAD) are the keys to explaining the plasma application mechanism. The experimental results show that the M-PSAD can produce plasma clusters and detonation waves. The thermal motion of charged particles in the plasma cluster is the main reason for the thermal effect of arc discharge. The detonation wave consists of the shock wave, Taylor expansion wave, and two different thickness zones of charged particles. The experimental results provide a profound physical mechanism for applying plasma.

A better understanding of the mechanism of flow separation suppression by a dielectric barrier discharge is essential for flow control. This paper investigates the mechanism of improving the aerodynamic performance of the airfoil by dielectric barrier discharge when the Reynolds number is in the range of 6 × 104–4 × 105. The results show that the disturbance of the gas discharge to the flow field will form a new flow structure. The fluctuating frequency of the new flow structure determines the ability of the plasma actuator to suppress flow separation. This investigation improves and develops the mechanism of plasma flow control.

Objective To explore the influencing factors of pain onset age and severe pain in patients with Hartofilakidis type I developmental dysplasia of the hip (DDH). Methods A retrospective study of 83 patients with DDH treated at our hospital from January 2017 to June 2021 was conducted. The pain onset age, patients’ demographic data, and radiographic parameters were collected. Multiple linear regression was used to determine the influencing factors of pain onset age. Cox regression analysis was used to determine the influencing factors of severe pain attacks. Results According to the results of multiple linear regression analysis, when the distance between the medial femoral head and the ilioischial line increased by one unit, the pain onset age decreased by 1.7 years (β = − 1.738, 95% CI: − 1.914–[–1.561], p p Exp [β]: = 1.090, 95% CI: 0.898–0.999, p = 0.04). For every unit increase in the distance between the medial femoral head and the ilioischial line, the likelihood of severe pain is 2.4 times higher than that of the original (Exp [β]: 2.417, 95% CI: 1.653–3.533, p

Jet flow-control technology is a promising area of fluid research. In this work, the flow-control effect of a curved-surface jet in an incoming flow of Mach = 5 and its underlying control mechanism are experimentally studied using high-speed photography and dynamic force measurement. From the establishment of complete stability of the flow field, the evolutionary process can be roughly divided into five stages: two equilibrium stages (short and long term), jet acceleration stage, bow shock formation stage, interference removal stage, and stable state. By defining the pressure ratio (PR) as an independent variable, it is found that the flow control of the jet occurs through different wave-system structures. The interaction between the jet and the incoming flow produces an oblique shockwave and expansion waves. The shockwave generates thrust and forms a virtual rudder surface; the expansion waves interact with the backflow region and the separated shear layer to generate lift. Moreover, PR has an optimal solution of PR opt. When PR opt, the effect of flow control is related to α, Ve, and ρe, and the greater the PR, the stronger the flow-control effect. When PR > PR opt, the flow-control effect is related to α and ρe, and the larger the PR, the weaker the effect of the shockwave and the stronger the effect of the expansion waves but the slower the growth. In experiments, the thrust, pitching moment, and lift increased by 17.43%, 17.75%, and 9.45%, respectively, because of the appearance of wave-system structure when PR opt = 201.32.

We discuss linear and nonlinear topological edge states on the bearded-bearded edge (BBE) and armchair-armchair edge (AAE) of two helical waveguide arrays with opposite helicity. The robustness of the linear topological edge state can be controlled by the helix radius, the angle of the incidence, and the amplitude of lattice potentials. In the nonlinear regime, multipole-like lattice quasisolitons may be found with a certain saturable nonlinear factor for AAE. The long-distance propagation dynamics of such quasisolitons are numerically studied from the evolution of their intensity patterns and the “center of mass”. On the contrary, no quasisoltion exists for BBE under the same conditions.

Min Li,1 Tianqing Huang,2 Xiaolan Li,3 Zhiwei Shi,3 Yue Sheng,4 Mimi Hu,3 Kui Song3 1Department of Pharmacy, The First Affiliated Hospital of Jishou University, Jishou, Hunan, 416000, People’s Republic of China; 2Department of Neurology, The First Affiliated Hospital of Jishou University, Jishou, Hunan, 416000, People’s Republic of China; 3Department of Hematology, The First Affiliated Hospital of Jishou University, Jishou, Hunan, 416000, People’s Republic of China; 4Department of Pediatrics, The First Affiliated Hospital of Jishou University, Jishou, Hunan, 416000, People’s Republic of ChinaCorrespondence: Kui SongDepartment of Hematology, The First Affiliated Hospital of Jishou University, Century Avenue, Jishou City, Hunan Province, 416000, People’s Republic of ChinaEmail js_hematology@163.comBackground: Checkpoint kinase 1 (CHK1) plays an important role in DNA damage response and cell cycle progression. Thus, targeting CHK1 is an efficient strategy for cancer therapy.Purpose: The present study aimed to investigate the potential therapeutic effects of GDC-0575, a CHK1-specific inhibitor, in colitis-associated cancer (CAC) and colitis.Methods: We established a DSS-induced acute colitis model and an azoxymethane/dextran sodium sulfate (DSS)-induced CAC model using mice and tested the effect of GDC-0575 on them. Flow cytometry and immunofluorescence were employed to investigate the infiltration of immune cells, and inflammatory cytokine expression in the colon of mice with CAC or colitis was investigated using ELISA and qPCR. We also investigated the correlation between CHK1 and CCL2/CCR2 in human colorectal cancer (CRC) tissues.Results: Administration of GDC-0575 significantly inhibited CHK1 expression in the colon and dramatically impaired the development of CAC and colitis in mice. Moreover, the inhibition of CHK1 expression resulted in efficient inhibition of infiltration by iNOS-positive macrophages, but had no significant effect on CD4 T cells, CD8 T cells, and myeloid-derived suppressor cells (MDSCs). Significant downregulation of TNF-α, IL-6, and IL-1β and dramatic upregulation of IL-10 were observed in the colons of both mice with CAC and colitis treated with GDC-0575. CCL2 expression was also downregulated by GDC-0575 in both mice with CAC and colitis; this was followed by the inhibition of CCR2+ macrophage infiltration in the colon. Furthermore, we report a positive correlation between CHK1 expression and CCL2/CCR2 expression in the malignant tissues of patients with CRC.Conclusion: Taken together, we infer that GDC-0575 impairs the development of CAC and colitis by regulating cytokine expression and inhibiting CCR2+ macrophage infiltration in mice colon.Keywords: colitis, colitis-associated cancer, CHK1, macrophage

The adhesion force between individual human hair fibers in a crosshair geometry was measured by observing their natural bending and adhesive jumps out of contact, using optical video microscopy. The hair fibers' natural elastic responses, calibrated by measuring their natural resonant frequencies, were used to measure the forces. Using a custom-designed, automated apparatus to measure thousands of individual hair-hair contacts along millimeter length scales of hair, it was found that a broad, yet characteristic, spatially variant distribution in adhesion force is measured on the 1 to 1000 nN scale for both clean and conditioner-treated hair fibers. Comparison between the measured adhesion forces and adhesion forces modeled from the hairs' surface topography (measured using confocal laser profilometry) shows they have a good order-of-magnitude agreement and have similar breadth and shape. The agreement between the measurements and the model suggests, perhaps unsurprisingly, that hair-hair adhesion is governed, to a first approximation, by the unique surface structure of the hairs' cuticles and, therefore, the large distribution in local mean curvature at the various individual contact points along the hairs' lengths. We posit that haircare products could best control the surface properties (or at least the adhesive properties) between hairs by directly modifying the hair surface microstructure.

To achieve perpetual flight, solar-powered UAVs (SPUAVs) need to convert sufficient solar energy into electricity during daylight flight. However, perpetual flight at middle and high latitude regions in winter days still poses great challenges for gaining enough solar energy due to the low sun elevation angle and short daylight duration. Among measures for flight endurance enhancement, tracking the sun through changing geometry of wing and orienting flight direction may be an effective design scheme for gaining more solar energy. In this paper, the energy optimization method for Z-shaped sun-tracking morphing-wing SPUAV is developed and used to investigate the advantages on energy performance of the optimal Z-shaped wing over the conventional planar wing. Energy optimization for a whole year's flight shows that the optimal Z-shaped wing is capable of achieving longer flight endurance, improving perpetual flight latitude and extending perpetual flight date efficiently compared with the planar wing, especially for the middle and high latitude regions during winter days. The investigation on implications of conversion efficiency of solar cells indicates that, with higher conversion efficiency of solar cells, the optimal Z-shaped wing is more effective to collect more net energy, retain more energy margin and achieve perpetual flight at higher latitude. The Z-shaped sun-tracking morphing-wing design combined with the energy optimization method proposed is helpful to increase flight endurance and improve perpetual flight latitude for SPUAVs.

There is an obvious aerodynamic interference problem that occurs for a quad tilt rotor in near-ground hovering or in the conversion operating condition. This paper presents an aerodynamic interference test of the quad tilt rotor in a wind tunnel. A 1:35 scale model of the quad tilt rotor is used in this test. To substitute for the ground, a moveable platform is designed in a low-speed open-loop wind tunnel to simulate different flight altitudes of the quad tilt rotor in hovering or forward flight. A rod six-component force balance is used to measure the loads on the aircraft, and the flow field below the airframe is captured using particle image velocimetry. The experimental results show that the ground effect is significant when the hover height above the ground is less than the rotor diameter of the quad tilt rotor aircraft, and the maximum upload of the airframe is approximately 12% of the total vertical thrust with the appearance of obvious fountain flow. During the conversion operating condition, the upload of the airframe is reduced compared with that in the hovering state, which is affected by rotor wake and incoming flow. The aerodynamic interference test results of the quad tilt rotor aircraft have important reference value in power system selection, control system design, and carrying capacity improvement with the advantage of ground effect.

The path following control of quad-rotors transporting uncertain payloads, whose control system is featured with time-variation, high nonlinearity and strong couplings among state variables and inputs, is investigated. Targeting this, an internal model frame-based disturbance attenuation control scheme that requires only rough model information is proposed. Firstly, a novel disturbance estimator (DE) for general single-input-single-output (SISO) system is proposed. Secondly, the DE proposed is applied in transporting unknown payloads by quad-rotors, to estimate the disturbances caused by the payloads for feedback compensation. Lastly, the control scheme based on internal model frame is designed to further reduce the remaining disturbances from disturbance estimation error.

Aiming at the LED (Light Emitting Diode) point sources with Lambertian distribution, we propose an improved mesh method to design a free form lens. For this method, a free-form surface is divided into two parts. A part is designed to be a refraction surface by using mesh method. Based on the refraction, the other part is designed to be a reflection surface. The combination of two parts forms a free-form surface lens. To take a petal-shaped lens as an example, simulation results show that the lens designed by using the improved mesh method can be higher illumination uniformity by comparing our method with the tradition method. When the radius of the light shape increases, the illumination uniformity increases, but the efficiency has no obvious change. When the distance between the point light source and the target plane increases, the illumination uniformity does not change significantly and the efficiency increases. Thus, the improved method can realize the limited illumination of light shape in the far and near field, so it will has broad application prospects in LED lighting.

Coal pyrolysis is generally considered to initiate by cleavage of weak covalent bonds bridged between aromatic rings. The C–C covalent bonds are predominant bridged linkages among the framework of coal, which have a critical influence on coal pyrolysis reaction but lack of direct online observation. Five representative coal-related model compounds containing C–C bridged bonds, polypropylene (PP), polyvinylpyrrolidone (PVP), poly-4-vinylpyridine (P4VP), polystyrene (PS) and poly-4-vinylphenol, were selected to pyrolyze in an in-situ pyrolysis vacuum ultraviolet photoionization mass spectrometry (Py-VUV-PIMS). The soft ionized mass spectral detection can provide product distribution and evolved information of original products and intermediates, which are the key evidence to understand the initiation, recombination and reaction routes during pyrolysis process. Online analysis of pyrolysis reaction was found to be priority with cracking of C–C bond in the five polymer samples, and homologous free radicals and original products, which mainly include monomers, dimers and their alkyl and alkenyl radicals, were detected. The results reveal the cleavage temperature of C–C covalent bond is deeply related to its chemical environment, and obvious conjugation effect and steric effect for the bridged linkage were observed. In addition, the effect of hydrogen bond was also observed during the pyrolysis of model compounds containing hydroxyl groups, and intramolecular or intermolecular hydrogen bonding reduced the temperature at which C–C bridged bonds break. The analogous fracture mode and pyrolysis behavior of coal-related model compounds, which are beneficial to understand the reaction route and mechanism of coal pyrolysis, were discussed based on the experimental observations and theoretical calculation.

We investigate the existence and stability of nonlocal surface solitons at the interface between linear media and nonlocal nonlinear media with two-dimensional (2D) parity-time ( PT )-symmetric optical lattices. We analytically obtain the nonlinearity-induced change of the refractive index by introducing a reasonable step function with the method of Fourier transform, and carry out the linear stability analysis for the surface solitons based on the response function of the infinite nonlocal medium. Numerical results show that nonlocal PT surface solitons can exist and be stable in 2D PT -symmetric optical lattices.

The nanosecond pulsed plasma discharge actuator is used on a flying wing aircraft. At the angles of attack rang from -4° to 28°, the impact of plasma actuator arrangement position and discharge frequency on lift-enhancement effect is tested. Oil flow visualization is used to investigate the surface flow pattern varies with angles of attack for the plasma actuator turned on and off. The result indicates that lift-enhancement can be achieved through the actuator discharges at large angles of attack on flying wing aircraft. The arrangement position and discharge frequency both have a significant impact on lift-enhancement effect. The actuator which arranged at the leading edge of the aircraft could get the best lift-enhancement effect. There exists an optimal discharge frequency, flow separation under this frequency can be effectively suppressed, which results the best lift-enhancement effect. The flow visualization test shows that the control mechanisms of the plasma actuator are to inject energy to the shear layer, thus increased the vortex strength. The vortices strengthen the mixing of the outer high-speed fluid with inner low-speed fluid, which effectively restrains the separation.

Baiyinhua coal was subjected to catalytic pyrolysis over HZSM-5 and Ni-modified HZSM-5 (Ni/HZSM-5) with a novel pyrolysis time-of-flight mass spectrometers (Py-TOF-MS) equipped with vacuum ultraviolet photoionization (VUVPI). The soft ionization of VUVPI allowed the detection of volatile organic compounds. The effect of HZSM-5 and Ni/HZSM-5 on distribution of coal pyrolysis products was online investigated. The coal pyrolysis products including alkanes, phenols, aromatics and sulfur containing compounds (H2S and CH3SH) were detected. In the presence of HZSM-5 and Ni/HZSM-5, the products from coal pyrolysis have higher content of substituted benzene and alkenes and lower content of phenols in comparison with that without catalyst. The catalysts promote the conversion of phenols products to aromatic hydrocarbons via dehydroxylation reaction. Ni/HZSM-5 exhibits better catalytic performance for generating products with higher aromatic content and less oxygen species than HZSM-5 alone. Temperature-evolved profiles of pyrolysis products were also measured. It was found that the peak temperature of alkenes and substituted benzene of catalytic pyrolysis shifts to lower temperature region while that of dihydroxybenzenes moves to higher temperature. This work demonstrates the good performance of Py-TOF-MS for the online study of the coal catalytic pyrolysis process.

We numerically investigate the existence and stability of nonlocal vector solitons with pseudo spin-orbit-coupling (SOC). The pseudo SOC is realized by a framework based on the spatial-domain copropagation of two beams with mutually orthogonal polarizations and opposite transverse components of the carrier wave vectors in nonlocal optical media. The numerical results show that there are two kinds of solutions for vector solitons, one is central symmetric, and the other is noncentral symmetric. The solitons may exist below a certain threshold value of the effective SOC strength in the system.

Federated learning provides a privacy-preserving mechanism for multiple participants to collaboratively train machine learning models without exchanging private data with each other. Existing federated learning algorithms can aggregate CNN models when the dataset is horizontally partitioned, but cannot be applied to vertically partitioned datasets. In this work, we demonstrate the image classification task in the vertical federated learning setting where each participant holds incomplete image pieces of all samples. We propose an approach called VFedConv to solve this problem and achieve the goal of training CNN models without revealing raw data. Different from traditional federated learning algorithms sharing model parameters in each training iteration, VFedConv shares hidden feature maps. Each client creates a local feature extractor and transmits the extracted feature maps to the server. A classifier model at the server-side is constructed with extracted feature maps as input and labels as output. Furthermore, we put forward the model transfer method to improve final performance. Extensive experiments demonstrate that the accuracy of VFedConv is close to the centralized model.

A method for the generation of tunable multi-degree-of-freedom rotations of vector beams on demand along a propagation direction is theoretically proposed. This generation can be achieved by a suitable vector superposition of three monochromatic non-coplanar beams, including a plane wave with elliptical polarization and two Bessel–Hermite–Gauss (BHG) beams with orthogonal polarization, the parameters of which were systematically chosen to obtain the different longitudinal characteristics of the field, i.e., the state of polarization (SoP), phase, and intensity. On one hand, both the incidence angles of the two BHG beams and the additional phase of the plane wave affect the rotation of the beam intensity and phase, but the incidence angle does not affect the rotation of the SoP. Moreover, the additional phase can lead to a change of the rotation angle of the SoP. On the other hand, the weight coefficients of the two BHG beams periodically change the beam intensity distribution along the propagation direction. Interestingly, the beam is non-diffracting, which means that energy is only exchanged internally and is conserved as a whole. This approach may find applications in dynamic multi-beam optical tweezers, atom guiding, materials processing, microscopy, and optical communications.

In this paper the configurations of shock wave-boundary layer interactions (SWBLI) are studied theoretically and experimentally in Mach number 2 and 2.5 flows on test models with various wedge angles ranging from to. The proposed theoretical method couples the free interaction theory (FIT) with the minimum entropy production (MEP) principle to predict the appearance of separation shock, resulting in convex, straight and concave separation shock waves according to different solution combinations, which agree well with current experiments. Additionally, several influences on SWBLI are studied experimentally, in which the parameters related to theoretical solutions are found mostly determining the flow configuration, and SWBLI is much more sensitive to incident shock strength than incoming flow properties. Separation could be suppressed by incident shock when the MEP solution is smaller than the FIT, while it could be intensified when the MEP solution is larger than FIT; by contrast, the effects of separation position and model mounting height could be very weak.

We design a framework based on the spatial-domain copropagation of two light beams with mutually orthogonal polarizations and opposite transverse components of carrier wave vectors in a nonlinear waveguide with randomly varying birefringence, the averaging with respect to which introduces an effective Manakov nonlinearity in the system. The corresponding two-component system of nonlinear Schr\"odinger equations is derived, being similar to the system of coupled one-dimensional Gross-Pitaevskii equations for a binary spin-orbit-coupled Bose-Einstein condensate. The system may also include an effective Rabi coupling (direct linear mixing of the components) and a periodic potential, representing a photonic-crystal structure in the underlying waveguide. For self-focusing and self-defocusing signs of nonlinearity, soliton solutions of several symmetry types are obtained by means of numerical methods, and their stability is investigated, including gap solitons in the case when the periodic potential is present.

Membrane distillation (MD) is a membrane-based thermal separation process. Vapor pressure difference between both sides of the membrane is the driving force for mass transfer of volatile compounds via the gas phase. A hydrophobic porous membrane is generally used as a barrier to isolate the feed from the volatiles permeated across the membrane. Although MD is a thermally energy-intensive process, it can be coupled with low-grade/waste heat sources to increase the overall thermal energy utilization efficiency or reduce thermal pollution. In this chapter, five aspects of MD were studied: • Configurations of MD and their applications in wastewater and water treatment • MD performance enhancement and employment scope broadening by membrane material and structure modifications • MD commercialization • Treatment cost analysis • Conclusion and future trends

This paper presents the design of microwave bandpass filters with frequency-dependent (FDC) coupling for power wireless private network communication. The filters are composed of four resonators arranged in the in-line and folded topology using substrate integrated waveguide (SIW) technology. The frequency-dependent coupling is implemented bya magnetic coupling iris and a balanced microstrip line with a pair of metallized via-holes, which produces an extra zero in comparison to classical approaches. To verify the characteristics of the proposed FDC, an in-line fourth-order substrate integrated waveguide bandpassfilter (BPF) with one transmission zero and a folded configuration BPF with one small negative slope for independently controlled transmission zero are designed.

To explore the feasibility of reducing cadmium (Cd) concentrations and alleviating Cd toxicity via selenium (Se), this study investigated the effects of Se on the root morphology, photosynthetic parameters, and Se, and Cd concentrations in winter wheat under different Cd stress levels. Three Cd levels (0, 5 and 10 μM) and three Se levels (0, 1 and 5 μM) were applied in a hydroponics test. The results showed that increases in Cd stress significantly decreased the shoot and root dry matter weight, root length, root volume, root effective surface area, root total surface area, Se concentration, Se accumulation, net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr) and intercellular CO2 concentration (Ci). Increases in Cd stress significantly increased the Cd concentration and accumulation in shoots and roots, the root average diameter, and the stomatal limiting value (Ls). There were significant relationships between the root Cd concentrations and the root morphology parameters, shoot Cd concentrations and photosynthetic characteristics of winter wheat. The Se1 and Se5 treatments effectively increased the shoot dry matter weight, root length, root volume, root effective surface area and root total surface area and decreased the shoot Cd concentration, when Cd stress was at the medium level (Cd5). Only the Se1 treatment effectively increased the Gs, Tr and Ci under the Cd5 treatment. When Cd stress was at the high level (Cd10), the Se5 treatment had greater effects on root growth than the Se1 treatment, the Se levels had no pronounced effect on the shoot dry weight and Cd concentration in winter wheat. Meanwhile, the root Se concentration was closely related to each root morphology parameter. Cd stress inhibited the root growth and leaf photosynthesis of winter wheat, and a high enough Se supply reduced the Cd toxicity by enhancing the root growth of winter wheat.

The high-angle-of-attack uncommanded roll oscillations are dangerous and cause significant challenges in flight control. This paper focuses on investigating the feasibility and performance of an artificial-intelligence method - “model-free reinforcement learning” (MFRL) on this issue, in both simulation and experiment. In simulation, two algorithms TD3 and SAC were used to learn the policies to suppress the roll oscillations of a widely used mathematical model. The agents only utilized current states as observation vector, and achieved perfect results. In the experiments, these two algorithms were used to learn the policies to suppress the roll oscillations of a flying-wing model which utilized spanwise blowing as its roll effectors. It is worth noting that unlike in simulation, the experiments investigated the influence of the observation vectors' memory size on training results. The results show that for both algorithms, the agents cannot learn good-enough policies when their observation spaces were constructed only by the current sensor data. This phenomenon, which is a big difference between experiments and simulations of MFRL, is due to the non-Markovian characteristic of the real-world dynamics caused by inevitable latencies. However, constructing the observation space using current and past sensor data help both the TD3 and SAC agents to learn great policies to suppress the oscillations using spanwise blowing in real world. Surprisingly, the trained agents showed some counterintuitive “smart” behaviors in tests.

Soliton complexes provide an effective way to study the interaction of solitons and the dynamics of nonlinear systems. Based on the realization of pseudo-Zeeman lattice in optics, the soliton components of the soliton complexes have different potential fields, and thus have different propagation characteristics. The interaction of the soliton components makes the soliton complexes exhibit novel and unique propagation characteristics, that is, passing through the lattice without reflection and the weak light controlling the strong light through the attraction between the components of the soliton complexes.

Baiyinhua (BYH) coal, a kind of lignite, was hydrothermally treated in an autoclave reactor at 200–350 °C for 30 min and the liquefaction behavior of the treated samples were investigated. To uncouple the complex behavior of the changes in structural characteristics and functional groups of treated samples, the structural change in BYH coal was investigated by thermogravimetry, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Results reveal that oxygen content and volatile matter in treated sample reduce and carbon content increases. The decrease in atomic ratio of oxygen to carbon and hydrogen to carbon of treated sample indicates the improvement in coalification degree. CO 2 and CO account for the overwhelming majority of gaseous products from hydrothermal treatment, which can be attributed to the significantly decrease of carboxyl and carbonyl content. The hydrothermal treatment involves the breakup of some weak bonds within coal structure, and the main structure of BYH coal does not change significantly. A desirable upgraded coal was obtained by hydrothermal treatment of BYH raw coal at 250 °C. The liquefaction behavior of coal can be improved by hydrothermal treatment at 250 °C, and the oil yield increases from 32.9 wt% (dry ash-free basis) of raw coal to 37.8 wt% (dry ash-free basis). This work illustrates that hydrothermal treatment is a promising approach for upgrading of low rank coal.

To explore the control efficiency of circulation flow control technology, a circulation control actuator with an independent gas source has been designed and applied in roll attitude control of a small unmanned aerial vehicle. The circulation control devices are arranged at the two ends of the wing on an unmanned aerial vehicle scale model, the changes in aerodynamic force and aerodynamic moment caused by turning on the actuator are measured in a wind tunnel, and the flow field characteristics are analysed using particle image velocimetry technology. The flight control effect of the roll attitude is verified via a flight test. Experimental and flight test results show that the control of roll attitude can be achieved by turning on the circulation control actuator on one side, and the maximum efficiency that the circulation control generates is equivalent to 8° aileron deflection with production of a favorable yaw moment to achieve a coordinated turn. The circulation control actuator can increase lift and reduce drag when opened on both sides simultaneously. The maximum lift-to-drag ratio of the UAV increased from 5 to 9, and this approach can also suppress flow separation and delay stall at high angles of attack. The aileron or trailing edge flaps can be replaced with circulation control actuators, and the circulation control technology can also be applied to aerodynamic performance improvement and flight control in other types of aircraft.

Direct coal liquefaction (DCL) was investigated using a deuterium tracer method which makes it possible to determine which structural positions in the coal react with H 2 or hydrogen-donor solvents, i.e. hydrogen-transfer mechanism. D 2 and/or 1,2,3,4-d 4 -tetralin (tetralin-d 4 ) were used in DCL of Bulianta coal at 7.0 MPa (initial charge pressure) and 445 °C for 0 or 60 min in a tubing-bomb microreactor. 2 H NMR and isotope ratio mass spectrometry (IRMS) were used to determine the distribution of deuterium in liquefaction solvent and products qualitatively and quantitatively. The 2 H NMR of solvents after DCL under a variety of conditions showed that the α-radical of tetralin is an important intermediate in hydrogen transfer to and exchange with coal, and the de/re-hydrogenation cycle of tetralin is not a dominating approach of hydrogen transfer in DCL. The distribution of deuterium in each structural position and the D/ 1 H in preasphaltenes and asphaltenes (PAA) under a variety of conditions showed that both hydrogen atoms in tetralin and H 2 could enter alkyl groups remote from aromatic nucleus of PAA in preference to aromatic nucleus and α to aromatic groups of PAA. The hydrogen atoms in tetralin are more easily to stabilize radicals from coal cracking to form PAA than those in H 2 during the heating-up stage of DCL. Both the kinetic isotope effect and electrophilic aromatic substitution reaction in DCL, indicating the existence of ionic reaction process besides a radical reaction process in DCL.

Unmanned Aerial Vehicles (UAVs) can extract energy to improve their range and endurance due to thermal updrafts in the environment via static soaring. In this paper, a soaring control strategy is improved based on multi-hole probe technology. A vertical wind speed estimation method based on the multi-hole probe is proposed to design thermal updraft identification, mode switching logic, and the soaring controller. Turn logic is used to determine the correct turn direction for UAVs when a thermal updraft is detected. A simulation environment containing a six-degree-of-freedom glider model and a thermal updraft model is described. The induced roll effect caused by the asymmetric vertical velocity distribution of thermal updraft is included in the simulations. The results show an improved soaring capability from the proposed soaring strategy. Thus, the proposed method based on a multi-hole probe is more accurate and robust, and the turn logic allows a glider to enter a thermal updraft more quickly. The more energy a glider can obtain from thermal updraft enables a lower soaring speed during static soaring.

Hypersonic aircraft represent an important area of aerospace development. Raising the aircraft lift-to-drag ratio, improving the efficiency of attitude control, and optimizing aerodynamic performance are important goals. Active flow control technology can improve the aerodynamic performance of the aircraft while optimizing its control attitude. In the field of low speed, subsonic speed, and supersonic speed, many experiments and numerical simulations have been carried out to verify the excellent auxiliary or control effects of active flow control technology on aircraft. In this paper, a two-dimensional hypersonic airfoil is selected to analyze the feasibility and control effect of jet flow control technology under hypersonic inflow, and a flow control scheme is designed to make the jet eject from the wing surface. First, the influence of different jet excitation parameters on the scheme is explored through numerical simulation, mainly including the Mach number, the jet location, the jet angle, and the change with the angle of attack. After that, typical excitation states of numerical simulation are selected for hypersonic wind tunnel experiment verification, whose results are in good agreement with those of the numerical simulation. The results prove that, under the condition of high altitude and low pressure, if jet excitation is applied on the surface of the hypersonic airfoil, a local high pressure area will be formed in front of the excitation port, and the differential pressure between upper and lower wings will be changed. It can optimize the aerodynamic characteristics, increase or reduce lift, produce pitching moment simultaneously, enhance the efficiency of the rudder surface, and assist attitude control.

We investigate numerically the propagation of an Airy-Gaussian vortex (AiGV) beam in the defected photonic lattices. The propagation properties of the AiGV beam are affected by positive and negative defects. Interestingly, we find that the intensity distribution of the AiGV beam focuses on the position of the defect and then forms a lattice soliton for the positive defect. On the contrary, the AiGV beam is diffused for the negative defect. The higher value the defected depth is, the more energy can be constrained by the positive defect and the shorter transmission distance for the beam forming a lattice soliton is. And the effect of nonlinear is smaller than the effect of defects. Moreover, by changing the effects of nonlinearity, the lattice modulation depth, the defect depth and the distribution factor, we can control the propagation distance for the AiGV beam focusing for the positive defect.