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Helicon wave plasma sources have the well-known advantages of high efficiency and high plasma density, with broad applications in many areas. The crucial mechanism lies with mode transitions, which has been an outstanding issue for years. We have built a fluid simulation model and further developed the Peking University Helicon Discharge code. The mode transitions, also known as density jumps, of a single-loop antenna discharge are reproduced in simulations for the first time. It is found that large-amplitude standing helicon waves (SHWs) are responsible for the mode transitions, similar to those of a resonant cavity for laser generation. This paper intends to give a complete and quantitative SHW resonance theory to explain the relationship of the mode transitions and the SHWs. The SHW resonance theory reasonably explains several key questions in helicon plasmas, such as mode transition and efficient power absorption, and helps to improve future plasma generation methods.

Arc plasma can be applied in hazardous solid waste disposal for higher temperature than common heating methods, but some practical issues exist in practical engineering application. In this study, an air arc plasma torch with double chambers and magnetic controlling is designed to realize wide variable power and long electrode life. The detailed characteristics and laws of the air arc are studied. The condition parameters of arc current (I), air flow rate (G) and the structure parameters of inlet area ratios and electrode diameters influence both the arc voltage and arc root positions. The arc rotating driven by magnetic field effectively lengthens the electrode life. The gasification process and product of organic wastes by air plasma are influenced largely by the waste compositions and the air flow rate. A furnace structure with more even atmosphere and longer residence time should be considered for better gasification. Oxygen-deficient environment is important to suppress NO x formation during the application of air plasma. Inorganic solid wastes can be melt by the air plasma and cooled down to form compact vitreous structures in which heavy metals can be locked and the leaching rates significantly decrease down.

With the continuous advancement of technology and the ever-increasing demand for information digitization in power systems, smart substations have become the most mainstream substations currently used in China. The secondary circuit and pressure plate of the intelligent substation are virtual forms constructed by internal software. There is no obvious electrical disconnection point, so there is a big difference in operation and maintenance and repair methods from conventional substations. Combined with the requirements of the intelligent station maintenance business, this paper proposes to deploy a “one-click” security system in the station control layer monitoring system of the intelligent substation. This system is only used as an additional module and does not depend on the software and hardware structure of the station control layer. It is of great significance to effectively improve the efficiency of intelligent secondary equipment operation inspection and better guarantee the safe and stable operation of the power grid.

With the increasing complexity of the power grid, in order to ensure the reliability and stability of the power supply system, higher requirements are imposed on the automation level of the power system. Substation security measures are generally performed manually, and maintenance personnel need to cast and withdraw pressure plates one by one based on the automatically generated secondary security measures, and manually verify the results of each step. This paper proposes a technology for the automatic execution of security measures in substations. Based on the generated security measures, it implements automatic sequence control operations and has proofreading functions. This method improves the level of substation automation while ensuring the correct execution results of safety measures, and provides an important guarantee for the safe and stable operation of the power system.

With the continuous deepening of smart grid construction, more and more smart substations are being used in actual projects. Compared with traditional substations, smart substations have realized digitalization of information, communication network, and standardization of sharing. However, the secondary circuit of intelligent substation has high integration and no obvious electrical isolation point, so the traditional safety measures are no longer suitable for the actual situation of intelligent substation. Therefore, based on the analysis of typical equipment security measures, this article designs a set of general rules for automatic generation of security measures according to the relevant specifications of security measures of intelligent substations. Through the modeling of different maintenance tasks, the characteristics of the safety measures applied to the intelligent substation equipment are analyzed, and the designed safety measures are classified according to the equipment type and operation mode to establish a safety measures database; finally, according to the established database Develop an automated ticket generation plan.

In this paper, the influence of admixture on plastic shrinkage cracking was studied. The results show that the plastic tensile strength increases while plastic shrinkage stress decreases as the content of air-entraining agent grows to 150×10-6 wt.%, and the anti-cracking index increases as a whole. Water reducing agent, water retaining agent, and shrinkage reducing agent all have the effect of improving plastic shrinkage cracking of fresh cement mortar. The constitutive relations between the admixtures content and anti-cracking index have been built.

We present the axial profiles of argon helicon plasma measured by a local optical emission spectroscope (OES) and Langmuir RF-compensated probe. The results show that the emission intensity of the argon atom lines (750 nm, 811 nm) is proportional to the plasma density determined by the Langmuir probe. The axial profile of helicon plasma depends on the discharge mode which changes with the RF power. Excited by helical antenna, the axial distribution of plasma density is similar to that of the external magnetic field in the capacitive coupled mode (E-mode). As the discharge mode changes into the inductively coupled mode (H-mode), the axial distribution of plasma density in the downstream can still be similar to that of the external magnetic field, but becomes more uniform in the upstream. When the discharge entered wave coupled mode (W-mode), the plasma becomes nearly uniform along the axis, showing a completely different profile from the magnetic field. The W-mode is expected to be a mixed pattern of helicon (H) and Trivelpiece-Gould (TG) waves.

In this work we used a passive measurement method based on a high-impedance electrostatic probe and an optical emission spectroscope (OES) to investigate the characteristics of the double layer (DL) in an argon helicon plasma. The DL can be confirmed by a rapid change in the plasma potential along the axis. The axial potential variation of the passive measurement shows that the DL forms near a region of strong magnetic field gradient when the plasma is operated in wave-coupled mode, and the DL strength increases at higher powers in this experiment. The emission intensity of the argon atom line, which is strongly dependent on the metastable atom concentration, shows a similar spatial distribution to the plasma potential along the axis. The emission intensity of the argon atom line and the argon ion line in the DL suggests the existence of an energetic electron population upstream of the DL. The electron density upstream is much higher than that downstream, which is mainly caused by these energetic electrons.

This paper investigates the entanglement in the supermolecular dimer [Mn4]2 consisting of a pair of single molecular magnets with antiferromagnetic exchange-coupling J. The conventional von Neumann entropy as a function of the exchange-coupling is calculated explicitly for all eigenstates with the quantum number range from M = M1+M2 = −9 to 0. It is shown that the von Neumann entropy is not a monotonic function of the coupling strength. However, it is significant that the entropy of entanglement has the maximum values and the minimum values for most eigenstates, which is extremely useful in the quantum computing. It also presents the time-evolution of entanglement from various initial states. The results are useful in the design of devices based on the entanglement of two molecular magnets.

The anti-Klein tunneling at normal incidence is a typical property of bilayer graphene. We study the resonant tunneling through multiple electrostatic barriers in bilayer graphene, and find that a line-type resonance with perfect transmission caused by quasibound states can occur at normal incidence, leading to the destruction of anti-Klein tunneling. The line-type resonance presents -fold splitting in n-barrier, while the Fabry–Perot resonance shows n-fold splitting, because they originate from different resonant states. The electronic states, the transmission region, and the features of both resonances are limited by the longitudinal wave vectors, which can be effectively controlled by adjusting the barrier height and barrier width.

By using the Faddeev–Senjanovic path integral quantization method, we quantize the composite fermions in quantum electrodynamics (QED). In the sense of Dirac’s conjecture, we deduce all the constraints and give Dirac’s gauge transformations (DGT). According to that the effective action is invariant under the DGT, we obtain the Noether theorem at the quantum level, which shows the fractional charges for the composite fermions in QED. This result is better than the one deduced from the equations of motion for the statistical potentials, because this result contains both odd and even fractional numbers. Furthermore, we deduce the Noether theorem from the invariance of the effective action under the rotational transformations in 2-dimensional (x;y) plane. The result shows that the composite fermions have fractional spins and fractional statistics. These anomalous properties are given by the constraints for the statistical gauge potential.