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Using a stereo camera system, a new diagnostic for the safety factor of the core plasma based on the pellet ablation trail is applied on the Experimental Advanced Superconducting Tokamak (EAST). In EAST discharge No. 128 874, a shattered pellet injection system is applied to inject a shattered neon pellet into the EAST. Since the strong magnetic field in tokamaks binds the ablated pellet material, the orientation of the pellet ablation trail is the same as the local magnetic field direction. Thus, from the three-dimensional reconstruction result of the pellet ablation trail, the local safety factor q can be obtained. The motional Stark effect (MSE) diagnostic is applied to determine the safety factor q profile in this shot. The determined safety factor q results for this new diagnostic are in quantitative agreement with those from the MSE diagnostic with the mean relative difference of only 6.8%, confirming the effectiveness of this new diagnostic of the safety factor. [ABSTRACT FROM AUTHOR]

Both positive and negative ions of N3O2 have been observed in various experiments. The neutral N3O2 was predicted to exist either as a weakly bound NO·N2O complex or a covalent molecule. The rovibrational spectrum of the NO(X2Π)–N2O complex has been measured for the first time in the 5.3 µm region using distributed quantum cascade lasers to probe the direct absorption in a slit-jet supersonic expansion. The observed spectrum is analyzed with a semi-rigid asymmetric rotor Hamiltonian for a planar open-shell complex, giving a bent geometry with an a-axis–NO angle of about 21.9°. The vibrationally averaged 2A′–2A″ energy separation is determined to be ε = 144.56(95) cm−1 for the ground state, indicating that the electronic orbital angular momentum is partially quenched upon complexation. Geometry optimizations of the complex restricted to a planar configuration at the RCCSD(T)/aug-cc-pVTZ level of theory show that the 2A″ state is more stable than the 2A′ state by about 110 cm−1 and the N atom of NO points to the central N atom of N2O at the minimum of the 2A″ state. [ABSTRACT FROM AUTHOR]

This article reports experimental observation of rotating plasma discharges in a coaxial structure at a frequency of 2.45 GHz and under atmospheric pressure. In contrast to other cases, the discharge in our case spins without external static magnetic field or moving electrodes. Its formation and impact factors are experimentally explored. Results show that the rotating discharge, especially the peculiarities of its rotation velocity, is attributed to the combined action of gas flow and electromagnetic field intensity between the conductors. Raising the electromagnetic field intensity or reducing the gas flow rate in appropriate ranges can result in a notable increase of the rotation speed. Experiments also demonstrate that the rotation properties are independent of the coaxial dimensions. This article is supposed to provide a new thinking and guidelines for inducing rotating discharge in a coaxial structure without electrodes moving or external magnetic field. [ABSTRACT FROM AUTHOR]

The rovibrational spectrum of the Ne–NO(X2Π) open-shell complex has been measured in the 5.3 µm region using distributed feed-back quantum cascade lasers to probe the direct absorption in a slit-jet supersonic expansion. Three P-subbands (P′ ← P″: 1/2 ← 1/2, 3/2 ← 1/2, and 5/2 ← 3/2) were observed, where P is the projection of the angular momentum J along the inertial a-axis of the complex. The hyperfine structure due to the nuclei spin of 14N (I = 1) was partially resolved in the P′ ← P″: 1/2 ← 1/2 and 3/2 ← 1/2 subbands. The observed mid-infrared spectrum of Ne–NO (X2Π) together with the previously reported microwave spectrum was analyzed using a modified semirigid asymmetric rotor Hamiltonian for a planar open-shell complex. The band origin is located at 1876.0606(97) cm−1, which is blue-shifted from that of the NO monomer by only 0.0888 cm−1. The complex shows strong structural relaxation upon excitation of the overall rotation and the internal rotation of the NO subunit. [ABSTRACT FROM AUTHOR]

The rovibrational spectrum of the Ar–NO open-shell complex has been measured in the 5.3 µm region using distributed feed-back quantum lasers to probe the direct absorption in a slit-jet supersonic expansion. Five P-subbands, namely, P ′ ← P ″ : 1 / 2 ← 3 / 2,1 / 2 ← 1 / 2,3 / 2 ← 1 / 2,5 / 2 ← 3 / 2 , and 7 / 2 ← 5 / 2 , are observed, with J up to 15.5. The hyperfine structure due to the nuclei spin of 14N (I = 1) can be partially resolved in the P ′ ← P ″ : 1 / 2 ← 3 / 2,1 / 2 ← 1 / 2 , and 3 / 2 ← 1 / 2 subbands. The fine structure of the observed spectrum is analyzed using a modified semi-rigid rotor Hamiltonian [W. M. Fawzy and J. T. Hougen, J. Mol. Spectrosc. 137, 154–165 (1989)] and an empirical Hamiltonian [Y. Kim and H. Meyer, Int. Rev. Phys. Chem. 20, 219–282 (2001)] separately. The hyperfine structure can be simulated successfully by including hyperfine terms to the semi-rigid rotor Hamiltonian. A linear J-dependence of the angle between the inertial a-axis of the complex and the intramolecular axis of the NO subunit is also introduced in order to model the strong structure relaxation effect in the P = 1/2 state. [ABSTRACT FROM AUTHOR]

To investigate the transport of small dusts as well as their evolution property along their trajectories, the NDS module is developed under the BOUT++ framework, a highly desirable C++ code package to perform parallel plasma fluid simulations with an arbitrary number of equations in three-dimensional curvilinear coordinates. Due to the severe dust ablation in fusion plasmas, the dust size would decrease from micrometer to nanometer, resulting in impurities. Small dusts in the simulations here are specified as tungsten spheres with the radii on or below the order of submicrometer. The Rayleigh limit is included in the charging process when the dust is ablated to the droplet phase. The simulation results from the NDS module show that a 200 nm radius spherical tungsten dust originated from upper divertor region of EAST Tokamak is ablated completely due to the intense heating from the incoming plasma inside the core region, well consistent with the CCD footage of EAST shot # 81459. It is also found that the magnetic field dominates the dust transport when the dust radius is below 100 nm during the ablation along the trajectory. Our simulations predict that a 10 nm radius spherical tungsten dust injected from the inner midplane is well constrained by the magnetic field, and it reaches the inner divertor target with a velocity on the order of km/s. [ABSTRACT FROM AUTHOR]

The single individual capability and insufficient endurance of unmanned aerial vehicles (UAVs) have always been problems in power inspection operations. This article is based on the new development needs of UAV inspection and proposes a new model of multi-UAVs collaborative inspection. On this basis, this article studies the decoupling and intelligent matching technology between airports and UAVs, task merging and splitting technology in complex multi-task situations, and proposes a safety inspection strategy for multi-UAVs collaborative operations to ensure the safety of operations in the multi-UAVs multi-nests collaborative inspection mode. Finally, a complete multi-UAV, multi-nests collaborative inspection strategy is constructed. [ABSTRACT FROM AUTHOR]

We consider typical environmental conditions, such as different shooting backgrounds, lighting, and shooting distances, and study adaptive shooting algorithms for unmanned aerial vehicle (UAV) on-site environments under typical working conditions to achieve high-quality acquisition of UAV inspection images and reduce the technical difficulty of artificial intelligence recognition of inspection images. Based on the collected high-quality images and the characteristics of unmanned aerial vehicle inspection images, a deep learning technology framework is adopted to study the intelligent identification method of hidden dangers in transmission line equipment and channel environment, achieving the intelligent recognition of pin level fine particle defects. [ABSTRACT FROM AUTHOR]

In recent years, unmanned aerial vehicle (UAV) inspection has become one of the main means of daily operation and maintenance of overhead transmission lines. Since the key components of the UAV inspection system are composed of electronic components, it relies on data communication to realize data link transmission. In the actual operation process, the complex electromagnetic field environment has an obvious impact on its control and communication performance, especially when inspecting near the DC line. In this paper, combined with the research on the safety assurance technology of UAV inspection operations, the electromagnetic field simulation model of the UAV inspection operation on DC transmission lines is established. The electromagnetic field distribution around the wire is analyzed when the UAV is at different inspection distances, and the influence range and degree of the DC electromagnetic field on UAV inspection system are obtained. A true test platform for the inspection safety distance of the ±500 kV line UAV inspection was built, and the inspection safety distance test and research of the small rotary-wing UAV with a typical size, structure, and material was carried out. Through the test, when the current of the transmission line is 3 kA, the minimum safety distance of the UAV inspection operation of the ±500 kV DC transmission line straight tower is 3 m, and the distance is corrected in combination with the current. The research results of this paper can provide technical support for the inspection operation of small multi-rotor UAVs on ±500 kV transmission lines. [ABSTRACT FROM AUTHOR]

An imaging scheme of shear-force atomic force microscope is proposed by exploiting the second resonance regime of the tuning fork probe. Theoretical analysis and experimental results demonstrate that the imaging scheme can deliver better sensitivity and higher resolution of topographic imaging. [ABSTRACT FROM AUTHOR]

This article investigated the discharge characteristics of Ar plasma sustained by a coaxial plasma jet under different microwave frequencies (433 MHz, 915 MHz, 2450 MHz, and 5800 MHz). Clear distinctions of the discharge characteristics such as excitation and plasma-sustaining power, shape, electron number density, electron temperature, and so on were experimentally obtained under these operating frequencies. The results demonstrated that microwave powers at different frequencies could excite distinct particles. The higher the microwave frequency, the lower the excitation and the plasma-sustaining power. However, these powers did not decline linearly to the increase in microwave frequency. The Ar plasma at a frequency of 5800 MHz exhibited an upside-down "bell" shape and a larger cross section, while those at other three frequencies seemed to have thin and long plumes. The investigation also revealed that the electron temperature increased and then decreased, while the electron number density and gas temperature elevated monotonously with increasing frequency. This study is intended to be helpful in determining the optimal frequency and design microwave plasma sources for certain applications. [ABSTRACT FROM AUTHOR]

A high efficiency of power coupling from the incident microwave to the discharge is a general demand for large-scale and high-power applications of microwave plasma torches. This paper aims to experimentally explore the possibility of improving the power coupling efficiency by choosing a proper glass tube in a microwave plasma torch with a metallic enclosure, rather than using additional tuning measures such as a movable short-circuited ending plunger or a three-stub tuner. The power coupling efficiencies for the glass tubes with different wall thicknesses were experimentally measured under different incident microwave powers and different pressures. The results showed that the power coupling efficiency was improved with the increase in the glass tube wall thickness in a wide range of operating conditions for the microwave plasma torch with specific dimensions. An efficiency higher than 85% can be achieved once the wall thickness of the glass tube is in a particular range. This indicates that external tuning measures can be reduced for the microwave plasma torch with a proper glass tube, which helps to save the cost of tuning devices and enhance the flexibility in different working environments. [ABSTRACT FROM AUTHOR]

Based on deep learning, a Dust Ablation Trail Analysis (DATA) code package is developed to detect dust ablation trails in tokamaks, which is intended to analyze a large amount data of tokamak dusts. To validate and benchmark the DATA code package, 2440 plasma jet images are exploited for the training and test of the deep learning DATA code package, since plasma jets resemble the shape and size of dust ablation clouds in tokamaks. After being trained by 1920 plasma jet images, the DATA code package is able to locate 100% plasma jets, classify plasma jets with the accuracy of >99.9%, and output image skeleton information for classified plasma jets. The DATA code package trained by the plasma jet images is also used to analyze the dust ablation trails captured in the Experimental Advanced Superconducting (EAST) tokamak with the satisfactory performance, further verifying its applicability in the fusion dust ablation investigation. Based on its excellent performance presented here, it is demonstrated that our DATA code package is able to automatically identify and analyze dust ablation trails in tokamaks, which can be used for further detailed investigations, such as the three-dimensional reconstruction of dusts and their ablation trails. [ABSTRACT FROM AUTHOR]

In this paper, the behaviors of single bubble in shear-thinning viscoelastic fluids were investigated using OpenFOAM. The volume-of-fluid method was used to capture the interface, and the Giesekus model was adopted for describing the rheological behaviors of shear-thinning viscoelastic fluids. The bubble cusp, negative wake, and velocity jump phenomenons in viscoelastic fluids were obtained, and the effects of wall effect, mobility factor α, and Weissenberg number (Wi) on bubble behaviors were investigated. The results showed that the viscoelastic stress is the main reason for the formation of bubble cusp, the relaxation of polymer macromolecules leads to the formation of negative wake, and the negative wake may be the main reason for the velocity jump. The open angle θ of the negative wake decreases and the distribution region in the vertical direction increases with the increasing Reynolds numbers (Re). In addition, the magnitude of the maximum negative velocity increases with Re and appears further away from the bubble cusp. Moreover, decreasing the wall effect can accelerate the formation of viscoelastic stress and make the bubble cusp appear earlier. As the mobility factor α increases, the viscosity and viscoelastic stress of the fluid near the bubble decrease; this causes the terminal velocity of the bubble to increase. As the Wi increases, both the maximum velocity and terminal velocity of the bubble increase, and the time lag occur. The viscoelastic stress τyy has a longer linear distribution at the tail of the bubble with the increase in Wi. [ABSTRACT FROM AUTHOR]

Sonodynamic therapy, with advantages in large tissue penetration depth and great controllability, is a promising type of non-invasive cancer treatment method. Developing sonosensitizers with high reactive oxygen species (ROS) quantum yield and the ability to regulate tumor microenvironment to achieve enhanced performances in sonodynamic therapy would thus be rather attractive. Herein, vanadium (V) doped TiO2 (V-TiO2) nanospindles with glutathione-depleting properties are fabricated for enhanced sonodynamic cancer therapy. Due to doping of the V element, the bandgap of V-TiO2 nanospindles is reduced, increasing the efficiency of ultrasound-triggered ROS production compared to that of pure TiO2 nanoparticles. More interestingly, the doping of V also makes V-TiO2 nanospindles an effective Fenton-like agent, which can catalyze the generation of highly toxic hydroxyl radicals (•OH) from endogenous H2O2 in the tumor, thus enabling cancer-killing through chemodynamic therapy. In addition, the V doping also endows V-TiO2 nanospindles with the function of glutathione depletion, further amplifying the oxidative stress generated by chemodynamic-sonodynamic therapy. In vitro cell experiments and in vivo animal experiments demonstrate that V-TiO2 nanospindles can effectively kill cancer by the combined chemodynamic-sonodynamic therapy, significantly improving the tumor treatment outcomes. Importantly, V-TiO2 with the ultrasmall spindle morphology can be quickly excreted from the body, without causing any long-term toxicity. This work illustrates that doping TiO2 with other special elements is a meaningful strategy to fabricate nanostructures with interesting functions useful in biomedicine. [ABSTRACT FROM AUTHOR]