Forbidden Zones Research Articles

Statistical analysis of Lagrangian transport of subtropical waters in the Japan Sea based on AVISO altimetry data

Abstract. Northward near-surface Lagrangian transport of subtropical waters in the Japan Sea frontal zone is simulated and analysed based on altimeter data for the period from 2 January 1993 to 15 June 2015. Computing different Lagrangian indicators for a large number of synthetic tracers launched weekly for 21 years in the southern part of the Sea, we find preferred transport pathways across the Subpolar Front. This cross-frontal transport is statistically shown to be meridionally inhomogeneous with gates and barriers whose locations are determined by the local advection velocity field. The gates open due to suitable dispositions of mesoscale eddies facilitating propagation of subtropical waters to the north. It is documented for the western, central and eastern gates with the help of different kinds of Lagrangian maps and verified by some tracks of available drifters. The transport through the gates occurs by a portion-like manner, i.e. subtropical tracers pass the gates in specific places and during specific time intervals. There are some forbidden zones in the frontal area where the northward transport has not been observed during all the observation period. They exist due to long-term peculiarities of the advection velocity field.

Numerically stable method for wave-field calculation and band-gap estimation in layered phononic crystals

High-frequency wave propagation in layered waveguides composed of periodic unit-cells is studied. Each unit-cell consists of a certain number of various elastic layers. Wave motion in the considered elastic structures (phononic crystals) is characterized by frequency bands, known as forbidden zones or band-gaps, where the full reflection of time-harmonic plane waves incident from an external half-space is observed. Using the transfer matrix method, the mathematical model of elastic wave propagation in anisotropic layered phononic crystals between two half-spaces is developed. A stable numerical algorithm for calculation of wave fields in the cells of phononic crystals is proposed. The amplitude coefficients of transmitted longitudinal and shear body waves are expressed in terms of transfer-matrix eigenvalues. A classification of band-gaps and pass-bands in layered anisotropic phononic crystals is proposed. It is based on the analysis of Bloch wavenumbers (expressed via the eigenvalues of the unit-cell transfer matrix) and the derived semi-analytical asymptotic expression of the transmission coefficients. Each Bloch wave has attenuation within the band-gaps of first kind. Waves propagating without attenuation are not excited within the band-gaps of second kind due to their specific polarization and boundary conditions at the interface between the multi-layered structure and the external half-space. By changing the parameters of the incident field, for instance, angles of incidence, band-gaps are converted into low transmission pass-bands where transmission coefficients are rather small. Therefore, a low transmission pass-band is similar to the traditional band-gap from an engineering point of view. The numerical results for energy transmission coefficient and Bloch waves are given at different angles of incidence; they demonstrate the formation of band-gaps in anisotropic phononic crystals.

On the forbidden and the optimum crystallographic variant of rutile in garnet

In many inclusion–host systems with similar oxygen packing schemes, the optimum crystallographic orientation relationship (COR) between the inclusion and the host is mostly determined by matching the similar oxygen sublattices of the two structures. In contrast, the prediction of the optimum COR or even just the rationalization of the observed COR(s) between an inclusion and host with incompatible oxygen sublattices, like rutile–garnet, is not straightforward. The related documentation for such cases is therefore limited. Given the abundant crystallographic data for the rutile–garnet system acquired by transmission electron microscopy and electron backscatter diffraction methods recently, this problem can now be examined in detail for the critical structural factors dictating the selection of optimum COR in such a structurally complicated system. On the basis of the unconstrained three-dimensional lattice point match and structural polyhedron match calculated for the observed CORs, it becomes clear that the prerequisite of optimum COR for rutile (rt) in garnet (grt) is to have most of their octahedra similarly oriented/inclined in space by aligning 〈103〉rt and 〈111〉grt for needle extension growth. Further rotation along the 〈103〉rt//〈111〉grt direction then leads to the energetically most favorable COR-2 variant with a good lattice point match defined by the coincidence site lattice (CSL) and a good topotaxial match of the constituent polyhedra at the CSL points, leaving unfavorable COR-1′ in the forbidden zones. This understanding sheds light not only on hierarchical energetics for the selection of inclusion variants in a complicated inclusion–host system, but also on yet-to-be-explored [UVW]-specific CORs and hetero-tilt boundaries for composite materials in general.

Universal scalings for laser acceleration of electrons in ion channels

We analytically investigate the acceleration of electrons undergoing betatron oscillations in an ion channel, driven by a laser beam propagating with superluminal (or luminal) phase velocity. The universal scalings for the maximum attainable electron energy are found for arbitrary laser and plasma parameters by deriving a set of dimensionless equations for paraxial ultra-relativistic electron motion. One of our analytic predictions is the emergence of forbidden zones in the electrons' phase space. For an individual electron, these give rise to a threshold-type dependence of the final energy gain on the laser intensity. The universal scalings are also generalized to the resonant laser interaction with the third harmonic of betatron motion and to the case when the laser beam is circularly polarized.

Bidding strategy of wind-thermal energy producers

This paper presents a stochastic mixed-integer linear programming approach for solving the self-scheduling problem of a price-taker thermal and wind power producer taking part in a pool-based electricity market. Uncertainty on electricity price and wind power is considered through a set of scenarios. Thermal units are modelled by variable costs, start-up costs and technical operating constraints, such as: forbidden operating zones, ramp up/down limits and minimum up/down time limits. An efficient mixed-integer linear program is presented to develop the offering strategies of the coordinated production of thermal and wind energy generation, having as a goal the maximization of profit. A case study with data from the Iberian Electricity Market is presented and results are discussed to show the effectiveness of the proposed approach.

Study of the Surfaces Defining the Area Boundaries of the Allowable Configurations of the Mobile Manipulator Mechanism with the Available Forbidden Zones

In this work the authors propose a method for analyzing information about the mechanism of the manipulator's positions and use of the restricted area in the field to set permissions in the configuration space of the generalized coordinates. Permissions' configuration reflects a model of the environment and is used in a system, which autonomously generates a robot's movement in accordance with the job description. Features of the manipulator are associated with the execution of the tasks in advance and on the eve of implementation of a virtually simulated movement. If the desired job is virtually modeled, it is executed as a sequence of operations with the use of the force-torque control algorithm and sensitizing system. At the same time, virtual modeling avoids unjustified and unnecessary movement of the manipulator in the presence of a motor redundancy. An approximate method for setting the resolved configurations is used in the collection of the planes and surfaces of the second order, limiting this area. The developed mathematical model of the area made feasible the configurations based on the use of the sets of inequalities and the unit of R-functions. Analysis of the relative position of the manipulator's motion paths and the field configurations admitted in the space of the generalized coordinates, allows predicting deadlocks, in which an arm can move. The results of the computational experiments and studies prove a reduction of the calculation time of the generalized vector of velocity and the trajectory of the manipulator motion in the phase of analysis of the mechanism of virtual manipulator interaction with the known environment. The analytical dependencies can be used in the intelligent control systems for the robots operating autonomously in the presence of the forbidden zones.

Green's functions of the scalar model of electromagnetic fields in sinusoidal superlattices

Problems of obtaining Green's function and using it for studying the structure of scalar electromagnetic fields in a sinusoidal superlattice are considered. An analytical solution of equation in the k-space for Green's function is found. Green's function in the r-space is obtained by both the numerical and the approximate analytical Fourier transformation of that solution. It is shown, that from the experimental study of Green's function in the k-space the position of the plane radiation source relative to the extremes of the dielectric permittivity ε(z) can be determined. The relief map of Green's function in the r-space shows that the structure of the field takes the form of chains of islets in the plane ωz, the number of which increases with increasing the distance from a radiation source. This effect leads to different frequency dependences of Green's function at different distances from the radiation source and can be used to measure the distance to the internal source. The real component of Green's function and its spatial decay in the forbidden zones in the near field is investigated. The local density of states, depending on the position of the source in the superlattice, is calculated.

Forbidden Zones: The Representation of Quiet Trauma in Recent British and French World War I Novels

Forbidden Zones: The Representation of Quiet Trauma in Recent British and French World War I Novels

Semiconductor superlattice zone diagram formation

Inroduction. In this paper the input impedance characteristics of unlimited and limited superlattices structures were investigated. Superlattices structures are periodic nanoscale multilayer structures in which a periodic potential of the crystal spatially additionally lattice modulated with potential of this structure. Superlattices’ impedance model. The expressions for input impedance on the left bound of unlimited crystal structure barrier were formed. Impedance characteristics of unlimited superlattices. The input impedance characteristics of unlimited structures were formed. The band nature of the superlattices’ structures through the dependence of active component of input impedance was shown. Impedance characteristics of limited superlattices. By the intercomparison of the reflection coefficient of the limited superlattices and active component of the input impedance of unlimited superlattices was analyzed the formation of the unlimited superlattices’ band diagram. As the result of the analysis of the parameters’ of the forbidden zones of limited superlattices and the number of superlattices’ barriers dependence was analyzed the degree of the parameters’ approximation of the limited superlattices’ band diagrams to the parameters of unlimited superlattice’s band diagram. Three points of matching were found. One point was located in the forbidden zone. The matching condition for the second and the third points meets resonance over-barrier passage of electrons through superlattices. Conclusions. They were found matching conditions of limited superlattices with the environment on their input as well as the features of the formation of the band diagram of superlattices.

The Delimited Method Research of Ecological Protection Red Line in Resources County

This paper analysis ecological environment characteristic of Resources County base on the delimited target of ecological protection red line, build a indicator system of ecological protection red line from the forbidden development zones, key eco-function zones, important eco-function zones and priority biodiversity zones, and determine the delimited technology method of ecological protection red line. Such as, finish the delimited of type-I and type-II red line and definite the protection emphasis and direction of ecological protection in red line zones.

Modules placement technique under constraint of FPGA forbidden zones

Runtime partial reconfiguration of programmable hardware devices can be applied to enhance many applications in high-end embedded systems, particularly those that employ recent platform FPGAs. Partial reconfigurable FPGAs allow tasks to be placed and removed dynamically at runtime. One of the challenging problems is the placement of modules on reconfigurable resources, this problem is called modules placement. Several modules placement techniques have been introduced in the literature to solve the modules placement problem. However, many designers have not considered forbidden zones inside the FPGA when loading the design. These forbidden zones inside FPGA might be the PowerPC, the Bloc RAMs, a design constraint, etc. Neglecting these FPGA forbidden zones may lead to incorrect design. In this paper, we present a new design method; the proposed method might be used early during the design process. It can help the designer to avoid FPGA forbidden zones when loading the design. Our method uses a typical mathematical formalism to load design on the device while avoiding the forbidden zones inside the FPGA and satisfying constraints at the same time. Experience shows that design results might be modified considerably when designer takes in account the FPGA forbidden zones.

A Thrust Allocation Method for Efficient Dynamic Positioning of a Semisubmersible Drilling Rig Based on the Hybrid Optimization Algorithm

A thrust allocation method was proposed based on a hybrid optimization algorithm to efficiently and dynamically position a semisubmersible drilling rig. That is, the thrust allocation was optimized to produce the generalized forces and moment required while at the same time minimizing the total power consumption under the premise that forbidden zones should be taken into account. An optimization problem was mathematically formulated to provide the optimal thrust allocation by introducing the corresponding design variables, objective function, and constraints. A hybrid optimization algorithm consisting of a genetic algorithm and a sequential quadratic programming (SQP) algorithm was selected and used to solve this problem. The proposed method was evaluated by applying it to a thrust allocation problem for a semisubmersible drilling rig. The results indicate that the proposed method can be used as part of a cost-effective strategy for thrust allocation of the rig.

Impact of propulsion system integration and controls on the vessel DP and manoeuvring capability

The paper presents recent insights in the DP manoeuvring capability of a marine vessel. The good integration of the propulsion system with the vessel design enhances the performance of the vessel under many circumstances. In parallel, the integration of the propulsion and engine controls plays an important role. The above is accentuated with the introduction of efficient propulsion unit and engine designs as driven by the current environmental legislation (Tier 3, EEDI, EEOI) affecting the overall vessel performance. The paper will review current advancement in propulsion and engine technologies (high and medium speed). In parallel, a number of test cases will be presented into detail with design specifics: 1) DP for drilling ships and offshore rigs. The importance of the propulsion design on the DP capability of the vessel will be shown based on the determination of the forbidden zones due to unit - to- unit interaction 2) Allowable fast RPM ramp-up of steerable thrusters. The issue is related to the inertia of the water to follow the propulsion unit acceleration and create the required thrust level. 3) Evaluation of manoeuvring of large vessels with tunnel thrusters, esp. with Fixed Pitch Propeller configurations (changing the thrust vector from full port to full starboard)

Attitude Reorientation of Spacecraft with Attitude Forbidden Zones

This paper investigates an attitude reorientation control scheme of spacecraft, considering attitude forbidden zone and external disturbances. A novel potential barrier function is proposed with an attitude constraint term and a dynamical scaling term. Here the dynamical scaling term is synthesized with a backstepping-based control scheme to accommodate both the avoidance of attitude forbidden zones and disturbance attenuation. Simulation results are given to verify the effectiveness of the proposed method.

Applications of Particle Swarm Optimization Algorithm to Solving the Economic Load Dispatch of Units in Power Systems with Valve-Point Effects

Reduction of operating costs in power system in order to return the investment costs and more profitability has vital importance in power industry. Economic Load Dispatch (ELD) is one of the most important issues in reducing operating costs. ELD is formulated as a nonlinear optimization problem with continuous variables within the power plants. The main purpose of this problem is optimal planning of power generation in power plants with minimum cost by total units, regarded to equality and inequality constraints including load demand and the range of units' power productivity. In this article, Economic Load Dispatch problem has been modeled by considering the valve-point loading effects with power plants' constraints such as: the balance of production and consumption in system, the forbidden zones, range of production, increasing and decreasing rates, reliability constraints and network security. To solve the problem, Particle Swarm Optimization (PSO) Algorithms has been employed. To evaluate the effectiveness of the proposed method, the problem has been implemented on a power system with 15 generating units and the results have been evaluated. DOI: http://dx.doi.org/10.11591/ijece.v4i6.6720

Self-scheduling and bidding strategies of thermal units with stochastic emission constraints

This paper is on the self-scheduling problem for a thermal power producer taking part in a pool-based electricity market as a price-taker, having bilateral contracts and emission-constrained. An approach based on stochastic mixed-integer linear programming approach is proposed for solving the self-scheduling problem. Uncertainty regarding electricity price is considered through a set of scenarios computed by simulation and scenario-reduction. Thermal units are modelled by variable costs, start-up costs and technical operating constraints, such as: forbidden operating zones, ramp up/down limits and minimum up/down time limits. A requirement on emission allowances to mitigate carbon footprint is modelled by a stochastic constraint. Supply functions for different emission allowance levels are accessed in order to establish the optimal bidding strategy. A case study is presented to illustrate the usefulness and the proficiency of the proposed approach in supporting biding strategies.

Borderland, No-Man's Land, Nature's Wonderland: Troubled Humanity and Untroubled Earth

Abstract Building on an interest in the presence of biodiversity where we do not expect to find it, this essay ponders the irony that human strife can be beneficial for the rest of nature by investigating the coexistence of troubled humanity and untroubled nature at various places around the world. It also looks at efforts to formalise the protection inadvertently provided in conflict and no-go zones after human tensions have abated. Focusing on borderlands, militarised landscapes, shatter zones, forbidden zones and other sites of upheaval and trauma, mostly in post-1945 Korea, Germany, Eastern Europe and Cyprus (but beginning with the nineteenth-century American West), I investigate the notion of the serendipitous survival of other-than-human nature and the 'threat' of demilitarisation and normalisation in places such as the Iron Curtain zone, where civilian activities may be more invasive and disruptive than military practices and other forms of restricted access. A related subject is the more recent, post-Cold War tale of nature's preservation, de facto and formal, in former environments of strife that also functioned involuntarily as shelter zones. This involves engagement with a particular manifestation of the deep-seated belief in nature's therapeutic value. The theme of the natural world's reconciliatory properties is pursued with reference to peace parks and other forms of transboundary conservation. I conclude with a discussion of the relationship between the narrative of nature and the narrative of history, specifically the belief that they are mutually exclusive and that the new emphasis on the 'return to nature' involves an act of erasure.

Feedback control for spacecraft reorientation under attitude constraints via convex potentials

A novel guidance algorithm is proposed for the attitude reorientation of a rigid body spacecraft in the presence of multiple types of attitude-constrained zones. In this direction, two types of attitude-constrained zones are first developed using unit quaternions, namely, the attitude-forbidden and -mandatory zones. The paper then utilizes a convex parameterization of forbidden and mandatory zones for constructing a strictly convex logarithmic barrier potential that is subsequently used for the synthesis of feedback attitude control laws while the inevitable unwinding phenomenon is given a simple and effective remedy. Model-independent and model-dependent control laws are then implemented by using the Lyapunov direct method and the modified integrator backstepping method. The paper concludes with a set of simulation results to evaluate the effectiveness and demonstrate the viability of the proposed methodology.

Fast and accurate solution for the SCUC problem in large-scale power systems using adapted binary programming and enhanced dual neural network

This paper presents a novel hybrid method for solving the security constrained unit commitment (SCUC) problem. The proposed formulation requires much less computation time in comparison with other methods while assuring the accuracy of the results. Furthermore, the framework provided here allows including an accurate description of warmth-dependent startup costs, valve point effects, multiple fuel costs, forbidden zones of operation, and AC load flow bounds. To solve the nonconvex problem, an adapted binary programming method and enhanced dual neural network model are utilized as optimization tools, and a procedure for AC power flow modeling is developed for including contingency/security issues, as new contributions to earlier studies. Unlike classical SCUC methods, the proposed method allows to simultaneously solve the unit commitment problem and comply with the network limits. In addition to conventional test systems, a real-world large-scale power system with 493 units has been used to fully validate the effectiveness of the novel hybrid method proposed.

Risk-Constrained Scheduling and Offering Strategies of a Price-Maker Hydro Producer Under Uncertainty

This paper presents a stochastic mixed-integer linear programming (SMILP) approach to maximize total expected profit of one price-maker hydro producer in a pool-based electricity market. Head dependence, commitment decisions, discharge ramping, startup costs and forbidden zones are all effectively handled in our approach. Uncertainty about the competitors' offers is adequately represented by residual demand curves (RDCs) scenarios. The management of risk is suitably addressed by conditional value-at-risk (CVaR) to provide the efficient frontier, i.e., the solutions set for which the expected profit may not be augmented without enlarging the variance of profit. Appropriate offering strategies to the pool are also developed, consisting of supply functions built for different risk levels. A representative cascaded hydro system with 7 reservoirs is considered to analyze and compare risk-neutral versus risk-averse results.