Forbidden Zones Research Articles

INVESTIGATION OF THE WIDTH OF THE FORBIDDEN ZONEHEAVILY DOPED SEMICONDUCTORS

The work examines changeswidth of the forbidden zoneheavily doped semiconductors. The introduction of impurities into the crystal lattice at low concentrations does not change the width forbidden zones semiconductor and does not affect the energy spectrum of electrons. Only discrete levels appear in the forbidden zone. When the concentration of impurities becomes large enough, the energy spectrum and the width of the BG of the crystal change.

Short-term load distribution model for giant cascade serial diversion-type hydropower stations

With the development of complex cascade serial diversion-type hydropower plants (CSDHP) in Southwest China, it has become imperative to study short-term scheduling challenges that are distinctive to this type of hydropower facility. Unlike conventional cascade hydropower stations, which have large reservoirs to regulate the outflow between stations, the CSDHP system consists of several diversion-type hydropower plants connected in series, requiring strict matching of turbine discharge between upstream and downstream facilities. In addition, these plants impose complex operation constraints, such as multiple units sharing one tunnel, which greatly increases the difficulty of short-term scheduling. This paper proposes a short-term optimal scheduling model for CSDHP systems aimed at achieving efficient load distribution among units while minimizing water consumption. The model takes into account the strict matching of turbine discharge and the complex constraints of multiple units sharing one tunnel. Subsequently, the model is transformed into a mixed integer linear programming problem using specified linearization techniques, with complexity further addressed via an iterative resolution method. A case study of a cascade illustrates the model’s efficacy in facilitating effective unit load distribution under complex hydraulic and electrical constraints, which substantially reduces the system’s water consumption by up to 6.1% during the dry season and 1.8% during the flood season, and reducing the number of crossing forbidden zones by 50.0% and 52.0%, respectively. The result shows the models’ potential to enhance day-ahead scheduling for the CSDHP system.

Irregular fixation: I. Fixed points and librating orbits of the Brown Hamiltonian

ABSTRACT In hierarchical triple systems, the inner binary is slowly perturbed by a distant companion, giving rise to large-scale oscillations in eccentricity and inclination, known as von-Zeipel–Lidov–Kozai oscillations. Stable systems with a mild hierarchy, where the period ratio is not too small, require an additional corrective term, known as the Brown Hamiltonian, to adequately account for their long-term evolution. Although the Brown Hamiltonian has been used to accurately describe the highly eccentric systems on circulating orbits where the periapse completes a complete revolution, the analysis near its elliptical fixed points had been overlooked. We derive analytically the modified fixed points including the Brown Hamiltonian and analyse its librating orbits (where the periapse motion is limited in range). We compare our result to the direct three-body integrations of millions of orbits and discuss the regimes of validity. We numerically discover the regions of orbital instability, allowed and forbidden librating zones with a complex, fractal, structure. The retrograde orbits, where the mutual inclination is $\iota \ \gt\ 90\ \rm deg$, are more stable and allowed to librate for larger areas of the parameter space. We find numerical fits for the librating-circulating boundary. Finally, we discuss the astrophysical implications for systems of satellites, stars, and compact objects. In a companion paper (Paper II), we apply our formalism to the orbits of irregular satellites around giant planets.

In Ukrainian

The paper describes the method of obtaining the SiC/porous-Si/Si heterostructure and the study of its structural and morphological properties. The method of obtaining heterostructures consisted of several stages: electrochemical etching of single-crystal silicon p-Si (111), annealing of porous Si in a CO atmosphere. The fabricated structures were characterized using scanning electron microscopy, X-ray spectral microanalysis, X-ray phase analysis, high-resolution diffractometry, X-ray reflectometry, and photoluminescence. The method of high-resolution diffractometry made it possible to assess the state of the SiC/Si(001) system. On the 2Theta-omega diffractograms, in addition to the (111) reflection of the Si substrate in the region of 2 Theta = 35.67, the (111) reflection of the cubic SiC film is observed. This means that the formed SiC film is textured in the (111) growth direction of the silicon substrate. The classical technique of X-ray phase analysis showed the presence of a hexagonal phase in the SiC film. The concentration ratio of cubic to hexagonal phase is 80 % cubic and 20 % hexagonal. The RMS deformation of the lattice (ε) in such a structure is ε = 1∙10–2. The photoluminescence spectra of the SiC films of the experimental samples in most cases consist of narrow and broad bands and extend from the near ultraviolet to the entire visible spectrum. At the same time, in the range of wavelengths corresponding to the energy forbidden zones of hexagonal polytypes and cubic polytypes, a noticeable glow was observed in most of the samples. In some samples, luminescence in the area of hexagonal phases was predominant. In the photoluminescence spectra both at T = 77 K and at T = 300 K, a narrow line at a wavelength of ~ 371 nm is observed.

Локализованные акустические волны в одномерных периодически модулированных структурах

A number of one-dimensional phononic crystals, which are periodic thin-film structures of various geometries, consisting of sets of columns and metal inclusions located on a piezoelectric half-space, have been proposed and studied. The features of propagation in such structures of acoustic waves localized near the free surface and inhomogeneous inclusions have been studied. An unusual behavior of the dispersion curves for the studied localized modes was discovered. Particular attention is drawn to the so-called forbidden zones, i.e. frequency ranges in which there are no propagating localized modes. The influence of mechanical and electrical boundary conditions on the spectrum of the waves under study is discussed in detail.

One step too far: social cerebellum in norm-violating navigation.

Social norms are pivotal in guiding social interactions. The current study investigated the potential contribution of the posterior cerebellum, a critical region involved in perceiving and comprehending the sequential dynamics of social actions, in detecting actions that either conform to or deviate from social norms. Participants engaged in a goal-directed task in which they observed others navigating towards a goal. The trajectories demonstrated either norm-violating (trespassing forbidden zones) or norm-following behaviors (avoiding forbidden zones). Results revealed that observing social norm-violating behaviors engaged the bilateral posterior cerebellar Crus 2 and the right temporoparietal junction (TPJ) from the mentalizing network, and the parahippocampal gyrus (PHG) to a greater extent than observing norm-following behaviors. These mentalizing regions were also activated when comparing social sequences against non-social and non-sequential control conditions. Reproducing norm-violating social trajectories observed earlier, activated the left cerebellar Crus 2 and the right PHG compared to reproducing norm-following trajectories. These findings illuminate the neural mechanisms in the cerebellum associated with detecting norm transgressions during social navigation, emphasizing the role of the posterior cerebellum in detecting and signaling deviations from anticipated sequences.

Analysis of forbidden zones in the spectrum of acoustic-gravity waves of an isothermal atmosphere

Analysis of forbidden zones in the spectrum of acoustic-gravity waves of an isothermal atmosphere

Control barrier function based trajectory generation and tracking control for spacecraft inspection mission under multiple safety constraints

In this paper, the safety control problem for spacecraft inspection mission is investigated, which means that there is no position and attitude obstacle collisions between the inspection spacecraft and the defined forbidden zones. We propose a control strategy that ensures safety, utilizing the control barrier function to address multiple safety constraints with logical relationships among them. Firstly, the position and attitude constraints are defined, and the hybrid logical relationship among different attitude constraints is analyzed. To handle complex position and attitude constraints, the Kreisselmeier-Steinhauser function is introduced to approximate the max/min function, thereby expressing them as continuous and differentiable functions. Subsequently, the control barrier function-based quadratic programming (CBF-QP) problems are solved to generate safe velocity and angular velocity. These problems have explicit solutions and do not require extensive computational resources. The safe position and attitude are then obtained by integrating the safe velocity and angular velocity. Notably, the forbidden regions are expanded by a constant in the construction of CBF-QP problems, which acts as a margin for the tracking controller’s performance. Finally, attitude and position tracking controllers based on the control Lyapunov barrier function (CLBF) are designed respectively, taking into account the lumped disturbance in the system, which means that the attitude and position control are computed independently. Numerical simulation results demonstrate that the proposed control strategy effectively handles complex constraints in inspection missions, ensuring system stability and safety, even under severe conditions.

Solutions of economic load dispatch problems for hybrid power plants using Dandelion optimizer

In this paper, an economic load dispatch problem (ELD) is solved for reaching optimal power output of hybrid systems in addition to cost minimization. The systems consider the forbidden working zones (FWZs), dynamic load demand, wind farms, and solar photovoltaic fields (SPs). The cost minimization solutions for the ELD problem are found by applying the Dandelion optimizer (DO), the salp swarm algorithm (SSA), and the particle swarm optimization (PSO). In the study case, the power system consists of six thermal power plants (TPs), two wind farms, and two SPs. In addition, the variation of load demand over 24 hours of one day is applied. DO and SSA can achieve the best cost of $15443.0753 for the first system, but PSO cannot. However, DO is the most stable method reaching the standard deviation of 0.0184 for fifty runs but that of SSA and PSO is about 1.0439 and 8.9664. For the second system, DO can reach smaller cost than PSO by $11.17, $137.74 and $323.09 for the best, mean and worst solutions among fifty found solutions. As a result, DO is strongly recommended for solving the ELD problem.

Localized defect modes’ tunability by Octonacci photonic bandgap structures with thin high-Tc superconductors

The reflectance spectrum, through 1D superconducting photonic bandgap structures organized following the Octonacci sequence, is studied by employing a theoretical calculation based on the transfer-matrix method and the two-fluid Gorter–Casimir theory. The proposed hetero-structures are made up of Yttrium oxide (A) and YBa2Cu3O7 (B) materials. We report the localization of modes for specific generations of the Octonacci sequence and TEM mode. We discuss the field-localization properties for different Octonacci sequences. It is noticed that localized defect modes of intensity scale up to 99% are sensitive to the wave-incident-angle and the TEM wave polarizations. The lateral position of the localized defect mode can be notably adjusted by the operating superconductor’s temperature (T), by applying a structural strain along the stacks, and by specific thicknesses of the used superconductor. The spectra exhibit forbidden wavelength zones around the localized defect modes in which the bandwidths increase with the strain coefficient h and under critical superconductor temperatures. The given structure has potential applications in tunable localized defect modes and is very useful in optical resonators.

Densely rewarded reinforcement learning for robust low-thrust trajectory optimization

To overcome the time-consuming training caused by the sparse reward function in reinforcement learning, an efficient dense reward framework for robust low-thrust trajectory optimization is proposed. The dense reward functions are designed separately for the deterministic and considered uncertain scenarios, including state uncertainties, observation uncertainties and execution uncertainties. For the uncertainties, the dense reward function is designed to diminish the deviation with respect to the isochronous nominal state along the corresponding deterministic optimal trajectory at each step, rendering the reward function no longer sparse and suitable for complex multirevolution problems. In addition, a multistage reward function of the terminal constraints for the rendezvous missions is designed by incorporating some exponential acceleration terms, enabling significant improvement in training efficiency as the terminal errors become low. In addition, a dense reward function for the deterministic scenario is also proposed via the introduction of empirical forbidden zones and an exponential term. The effectiveness and efficiency of the proposed method is demonstrated in a simple Earth-Mars mission and a complex Earth-Venus multirevolution mission. The promising results verify the significant effect of the proposed method in speeding up the process of training an initial incapable agent to an ‘expert’ while guaranteeing or even improving the performance.

Dynamic Behavior and Double-Parameter Self-Adaptive Stability Control of a Gear Transmission System

This paper proposes a new nonlinear transverse-torsional coupled model for single-stage gear transmission system, by taking transmission error, time-varying meshing stiffness, backlash, bearing clearances and the self-adaptive double-parameter control module into account. The nonlinear differential governing equation of system motion is derived and solved by applying variable step-size Runge–Kutta numerical integration method. The system’s nonlinear dynamic characteristics and stability are investigated systematically by a bifurcation diagram of the Poincaré map and parameter stability region. Firstly, the velocity bifurcation diagrams have shown that, under the same damping ratio and backlash and with the increase of control parameter [Formula: see text], the route to chaos in the subcritical velocity region is first experienced from crisis to periodic doubling, and to crisis again, but the route that reverts to periodic motion in the super-critical velocity region is not affected. Additionally, the backlash is found to be the key parameter to affect the route to chaos as well. With the increase of the backlash, the crisis becomes the unique route to chaos in sub-critical region no matter what the [Formula: see text] is, but the increase of [Formula: see text] could change the route that reverts to periodic motion from 3T-periodic attractor to 2T-periodic attractor. Secondly, with the increase of the control parameter [Formula: see text], the system starts to enter the chaotic motion and exit the chaos state at different critical points and through different routes. Besides, the unstable region could shrink dramatically and the route to crisis is suppressed as well with the increase of damping ratio. Thirdly, the motion stability region analysis established in full range of double-parameter and velocity provides a mathematical reference model and is stored in control module, which could be utilized to make the control module seek a nearest parameter set automatically that could make the motion stable again in the quickest way under unstable working condition. Finally, according to global motion stability diagram, the forbidden zones that cannot make the system motion stable by adjusting single control parameter are revealed, which has remarkable guiding value during the practical operation especially under the manual adjusting working condition.

Data-Independent Acquisition Phosphoproteomics of Urinary Extracellular Vesicles Enables Renal Cell Carcinoma Grade Differentiation

Translating the research capability and knowledge in cancer signaling into clinical settings has been slow and ineffective. Recently, extracellular vesicles (EVs) have emerged as a promising source for developing disease phosphoprotein markers to monitor disease status. This study focuses on the development of a robust data-independent acquisition (DIA) using mass spectrometry to profile urinary EV phosphoproteomics for renal cell cancer (RCC) grades differentiation. We examined gas-phase fractionated library, direct DIA (library-free), forbidden zones, and several different windowing schemes. After the development of a DIA mass spectrometry method for EV phosphoproteomics, we applied the strategy to identify and quantify urinary EV phosphoproteomes from 57 individuals representing low-grade clear cell RCC, high-grade clear cell RCC, chronic kidney disease, and healthy control individuals. Urinary EVs were efficiently isolated by functional magnetic beads, and EV phosphopeptides were subsequently enriched by PolyMAC. We quantified 2584 unique phosphosites and observed that multiple prominent cancer-related pathways, such as ErbB signaling, renal cell carcinoma, and regulation of actin cytoskeleton, were only upregulated in high-grade clear cell RCC. These results show that EV phosphoproteome analysis utilizing our optimized procedure of EV isolation, phosphopeptide enrichment, and DIA method provides a powerful tool for future clinical applications.

UAV Path Planning in Multi-Task Environments with Risks through Natural Language Understanding

Path planning using handcrafted waypoints is inefficient for a multi-task UAV operating in dynamic environments with potential risks such as bad weather, obstacles, or forbidden zones, among others. In this paper, we propose an automatic path planning method through natural language that instructs the UAV with compound commands about the tasks and the corresponding regions in a given map. First, we analyze the characteristics of the tasks and we model each task with a parameterized zone. Then, we use deep neural networks to segment the natural language commands into a sequence of labeled words, from which the semantics are extracted to select the waypoints and trajectory patterns accordingly. Finally, paths between the waypoints are generated using rapidly exploring random trees (RRT) or Dubins curves based on the task requirements. We demonstrate the effectiveness of the proposed method using a simulated quadrotor UAV that follows sequential commands in four typical tasks with potential risks.

Robust Optimization for the Self-Scheduling and Bidding Strategies of a Hydroproducer Considering the Impacts of Crossing Forbidden Zones

Giant hydrounits are usually accompanied by multiple head-dependent forbidden zones (FZs). FZs intensify hydropower systems’ head effects and affect the safe and economic operations in a deregulated market environment, especially in southwest China. This paper addresses the self-scheduling and bidding strategies of a typical hydroproducer (the Longtan hydroplant, the leading plant on the Hongshuihe River, one of the most important plants in the West-East Electricity Transmission Project in China) with irregular forbidden zones (IFZs) in a day-ahead market. Considering the impacts of crossing IFZs and the head effects, a robust optimization-based approach to maximize profits was developed to establish market-oriented strategies under asymmetric price intervals and is solved by an iterative algorithm.The complicated model with nonconvex and nonlinear features was recast into a robust mixed-integer linear programming (MILP) model. Finally, the optimal self-scheduling of a hydroproducer with IFZs in southwest China was used to show the effectiveness of the proposed model. The optimization results demonstrated that the proposed model can effectively incorporate the head effects and the impacts of crossing IFZs to maximize profits; furthermore, the model significantly reduced the phenomenon of crossing IFZs and provided more executable, stable, and safe generation scheduling. Additionally, the proposed model can obtain more profitable optimal bidding strategies than the model that ignores the impacts of crossing IFZs.

Combining Online Diagnosis and Prognosis for Safe Controllability

In this article, we combine fault diagnosis and prognosis to generalize the notion of safe controllability of discrete-event systems. To do so, we reformulate the notions of safe diagnosability, prognosability, safe controllability by diagnosis, and safe controllability by prognosis in the context of strings. Moreover, we combine these notions to introduce the concept of safe controllability by diagnosis or prognosis, or simply DP-safe controllability. We show that a language can be DP-safe controllable even if it is not safe controllable either only by diagnosis or only by prognosis. Thus, the DP-safe controllability can be considered a generalization of the safe controllability concept found in the literature. If a DES is DP-safe controllable, to achieve fault tolerance using an active approach, reconfiguration actions could be forced based not only on online fault diagnosis, but also on online fault prognosis. Thus, our approach outperforms the previous ones, since it provides additional control options to keep the system away from forbidden zones and to switch from the nominal supervisor to a postfault-detection supervisor designed to achieve postfault performance objectives. Necessary and sufficient conditions for DP-safe controllability are presented and an example is used to illustrate the introduced concepts.

The Method of Transport Logistics Problem Solving by the MAX-MIN ACO Algorithm

The article provides a detailed analysis of the well-known mathematical methods that are used in solving transport logistics problems of various types. Their advantages and disadvantages are determined. The article proposes to use the methods of swarm intelligence to find the optimal route, taking into account all forbidden zones. The problem of transport logistics was solved by the ant colony optimization algorithm on a control example. The results of work of the method were analyzed. The main disadvantages are established. It is proposed to use a modification of the ant colony algorithm - the Max-Min ant colony optimization algorithm. The effectiveness of the method for solving the problem of transport logistics by the algorithm of max-min optimization of an ant colony was tested on a control example. An experimental calculation of the optimal route of traffic from the starting point to the final point is given taking into account the forbidden zones.

Dispersion effects and real atomic vibrations of impure crystals studied based on interatomic effective potential

The dispersion effects and real atomic vibrations of crystals containing doping atoms have been studied using the interatomic effective potential which includes the many-body effects based on the contributions of nearest neighbors of the host and doping atoms. The analytical expressions are derived for the dispersion relations describing the dispersion effects consisting of the acoustic and optic branches, forbidden zone, as well as for the amplitude and phase shift of the real atomic vibrations of impure crystals. The Morse potential is assumed to describe the single-pair atomic interaction. The interrupts of wave propagation caused by doping atoms and the changes of thermodynamic properties due to the real atomic vibrations, as well as the areas of localization of forbidden zones and doping atoms have been specified. The numerical results for Fe doped by atoms of W calculated by the present theory using the interatomic effective potential are found to be in good agreement with experiment obtained from the measured Morse potential parameters and quite different from those of its inverse doping process (W doped by atoms of Fe), while they are the same if the single-pair potential is used.

On the maximal operator of a general Ornstein–Uhlenbeck semigroup

AbstractIf Q is a real, symmetric and positive definite $$n\times n$$ n × n matrix, and B a real $$n\times n$$ n × n matrix whose eigenvalues have negative real parts, we consider the Ornstein–Uhlenbeck semigroup on $$\mathbb {R}^n$$ R n with covariance Q and drift matrix B. Our main result says that the associated maximal operator is of weak type (1, 1) with respect to the invariant measure. The proof has a geometric gist and hinges on the “forbidden zones method” previously introduced by the third author.

Stirred Kardar-Parisi-Zhang Equation with Quenched Random Noise: Emergence of Induced Nonlinearity

We study the stochastic Kardar-Parisi-Zhang equation for kinetic roughening where the time-independent (columnar or spatially quenched) Gaussian random noise f(t,x) is specified by the pair correlation function ⟨f(t,x)f(t′,x′)⟩∝δ(d)(x−x′), d being the dimension of space. The field-theoretic renormalization group analysis shows that the effect of turbulent motion of the environment (modelled by the coupling with the velocity field described by the Kazantsev-Kraichnan statistical ensemble for an incompressible fluid) gives rise to a new nonlinear term, quadratic in the velocity field. It turns out that this “induced” nonlinearity strongly affects the scaling behaviour in several universality classes (types of long-time, large-scale asymptotic regimes) even when the turbulent advection appears irrelevant in itself. Practical calculation of the critical exponents (that determine the universality classes) is performed to the first order of the double expansion in ε=4−d and the velocity exponent ξ (one-loop approximation). As is the case with most “descendants” of the Kardar-Parisi-Zhang model, some relevant fixed points of the renormalization group equations lie in “forbidden zones”, i.e., in those corresponding to negative kinetic coefficients or complex couplings. This persistent phenomenon in stochastic non-equilibrium models requires careful and inventive physical interpretation.