Roof Subsidence and Movement Law of Composite Strata Mining: Insights from Physical and Numerical Modeling

Sinking and horizontal movements are necessary parameters for assessing the potential impacts of surface subsidence in mining activities. Based on similarity criteria, the surface subsidence mechanism was studied using a physical model composed of similar materials such as sand, cement, and gypsum. With constant field geological parameters maintained in two angles of a coal seam, models of roof subsidence of composite rock were compared for different mining configurations. In accordance with observations from the physical model, it was concluded that subsidence and horizontal movement of strata near to and far from the coal seams were different and divided into five zones. The zone above a mined-out area underwent greater total subsidence compared to unexploited regions on both sides. Correlations between a subsidence curve and the height of a caving zone and the mining dip angle were obtained and verified from numerical model results. According to the roof’s position relative to the goaf, the area above the goaf of the composite rock layer was divided into three regions: a curving zone, a water-conducting fracture zone, and a falling zone, to which the subsidence and movement characteristics of each area could be proposed. Compared with the subsidence and movement characteristics observed from the physical and numerical model, the acquisition of subsidence characteristics and parameters in different areas can provide an idea for improvement, innovation or proposal of a theoretical formula for subsidence prediction of composite rock formations.

OPTIMIZATION OF "GLUCOSE 11C" PHARMACEUTICAL PRODUCTION ON THE BEAM OF ELECTRON ACCELERATOR

The process of "Glucose 11C" pharmaceutical production by means of a photonuclear reaction 12C(γ, n) 11C is considered. The parameters of bremsstrahlung and electron beam scattered in the converter are investigated and optimized. It is proposed to use a constant-field magnet to remove electrons from the photon beam. A magnet de-sign is proposed that allows obtaining a field of 0.5 T in a gap of 25 mm. The production of the 11C isotope in the glucose target was estimated.

Relativistic Landau quantization in non-uniform magnetic field and its applications to white dwarfs and quantum information

We investigate the two-dimensional motion of relativistic cold electrons in the presence of `strictly’ spatially varying magnetic fields satisfying, however, no magnetic monopole condition. We find that the degeneracy of Landau levels, which arises in the case of the constant magnetic field, lifts out when the field is variable and the energy levels of spin-up and spin-down electrons align in an interesting way depending on the nature of change of field. Also, the varying magnetic field splits Landau levels of electrons with zero angular momentum from positive angular momentum, unlike the constant field which only can split the levels between positive and negative angular momenta. Exploring Landau quantization in non-uniform magnetic fields is a unique venture on its own and has interdisciplinary implications in the fields ranging from condensed matter to astrophysics to quantum information. As examples, we show magnetized white dwarfs, with varying magnetic fields, involved simultaneously with Lorentz force and Landau quantization affecting the underlying degenerate electron gas, exhibiting a significant violation of the Chandrasekhar mass-limit; and an increase in quantum speed of electrons in the presence of a spatially growing magnetic field.

Stacking Ensemble Methodology Using Deep Learning and ARIMA Models for Short-Term Load Forecasting

Short-Term Load Forecasting is critical for reliable power system operation, and the search for enhanced methodologies has been a constant field of investigation, particularly in an increasingly competitive environment where the market operator and its participants need to better inform their decisions. Hence, it is important to continue advancing in terms of forecasting accuracy and consistency. This paper presents a new deep learning-based ensemble methodology for 24 h ahead load forecasting, where an automatic framework is proposed to select the best Box-Jenkins models (ARIMA Forecasters), from a wide-range of combinations. The method is distinct in its parameters but more importantly in considering different batches of historical (training) data, thus benefiting from prediction models focused on recent and longer load trends. Afterwards, these accurate predictions, mainly the linear components of the load time-series, are fed to the ensemble Deep Forward Neural Network. This flexible type of network architecture not only functions as a combiner but also receives additional historical and auxiliary data to further its generalization capabilities. Numerical testing using New England market data validated the proposed ensemble approach with diverse base forecasters, achieving promising results in comparison with other state-of-the-art methods.

On the electrical passivity of astrocyte potassium conductance

Predominant expression of leak-type K+ channels provides astrocytes a high membrane permeability to K+ ions and a hyperpolarized membrane potential that are crucial for astrocyte function in brain homeostasis. In functionally mature astrocytes, the expression of leak K+ channels creates a unique membrane K+ conductance that lacks voltage-dependent rectification. Accordingly, the conductance is named ohmic or passive K+ conductance. Several inwardly rectifiers and two-pore domain K+ channels have been investigated for their contributions to passive conductance. Meanwhile, gap junctional coupling has been postulated to underlie the passive behavior of membrane conductance. It is now clear that the intrinsic properties of K+ channels and gap junctional coupling can each act alone or together to bring about a passive behavior of astrocyte conductance. Additionally, while the passive conductance can generally be viewed as a K+ conductance, the actual representation of this conductance is a combined expression of multiple known and unknown K+ channels, which has been further modified by the intricate morphology of individual astrocytes and syncytial gap junctional coupling. The expression of the inwardly rectifying K+ channels explains the inward-going component of passive conductance disobeying Goldman-Hodgkin-Kate (GHK) constant field outward rectification. However, the K+ channels encoding the outward-going passive currents remain to be determined in the future. Here, we review our current understanding of ion channels and biophysical mechanisms engaged in the passive astrocyte K+ conductance, propose new studies to resolve this long-standing puzzle in astrocyte physiology, and discuss the functional implication(s) of passive behavior of K+ conductance on astrocyte physiology.

Self-Organization of Charged Particles in an Electric Field

Self-organization in small systems of particles with simple dynamic laws has been simulated. The purpose of this work was to investigate self-organization in small systems of charged particles under the influence of an electric field where we could follow individual particles. There are positively and negatively charged particles. The intention is to look for pattern formation as the system evolves. Three electric fields and the particle-to-particle interactions were utilized to provide the forces. The three electric fields were a constant field, a ramp field, and an oscillatory field. The final system states for various electric fields are presented. For the two kinds of particles simulated, like particles have a repulsive force, while unlike particles have an attractive force. Initially, the particles are randomly distributed in a two dimensional square bounded region, and then allowed to dynamically interact for a number of iterations. Using the inverse square law force, modified at short distances, most cases resulted in equilibrium with the particles of opposite polarity paired up. Since this was a state of equilibrium no more movement occurred. The results of the experiments are presented in graphical format. The main conclusions are that this model can be used to study small dynamic systems, and that the presence of an external electric field does not significantly modify the final configuration but hastens the development of the equilibrium state.

Electrical TCAD Study of the Low-Voltage Avalanche-Mode Superjunction LED

The CMOS silicon avalanche-mode light-emitting diode (AMLED) has emerged as a potential light source for monolithic optical interconnects. Earlier we presented a superjunction light-emitting diode (SJLED) that offers a higher electroluminescent intensity compared to a conventional AMLED because of its more uniform field distribution. However, for reducing power consumption low-voltage (< 15V) SJLEDs are desired, not explored before. In this work we present a TCAD simulation feasibility study of the low-voltage SJLED for various doping concentrations and device dimensions. The results show that for obtaining a constant field, approximately a ten-fold more aggressive charge balance condition in the SJLED is estimated than traditionally reported. This is important for establishing a guideline to realize optimized RESURF and SJLEDs in the ever-shrinking advanced CMOS nodes.

Electrical TCAD Study of the Low-Voltage Avalanche-Mode Superjunction LED

The CMOS silicon avalanche-mode light-emitting diode (AMLED) has emerged as a potential light source for monolithic optical interconnects. Earlier we presented a superjunction light-emitting diode (SJLED) that offers a higher electroluminescent intensity compared to a conventional AMLED because of its more uniform field distribution. However, for reducing power consumption low-voltage (< 15V) SJLEDs are desired, not explored before. In this work we present a TCAD simulation feasibility study of the low-voltage SJLED for various doping concentrations and device dimensions. The results show that for obtaining a constant field, approximately a ten-fold more aggressive charge balance condition in the SJLED is estimated than traditionally reported. This is important for establishing a guideline to realize optimized RESURF and SJLEDs in the ever-shrinking advanced CMOS nodes.