Nearest-neighbour Exclusion Research Articles

Multiobjective coordinated search algorithm for swarm of UAVs based on 3D-simplified virtual forced model

This paper aims to tackle the problem of multiobjective search for swarms of UAVs in unknown complex environments and proposes a multiobjective coordinated search algorithm based on a 3D-simplified virtual forced model (MOCS-3D-SVFM). First, it decomposes the search behaviour into the roaming search state and coordinated search state based on the detection of target signals by a swarm of UAVs. Second, a nearest neighbour exclusion diffusion (NNED) algorithm is introduced for the UAV of the wander search state, and a 3D adaptive inertia weight extended particle swarm algorithm (IAEPSO) is proposed by combining the motion characteristics of UAV with a 3D particle swarm algorithm aiming at the UAV with coordinated search state. Finally, the 3D-simplified virtual force model proposed based on the concept of the 2D-simplified virtual force model by the rotation matrix is introduced to solve the model parameters and the control strategy under the UAV of wander search state and coordinated search state is established, which effectively solves the real-time obstacle avoidance problem. Moreover, this paper sets the comparison mode of the three search methods; compared to Mode1, the search time T and energy consumption S can be significantly reduced, and the numerical simulations verify its effectiveness.

Spinon bases in supersymmetric CFTs

We present a novel way to organise the finite size spectra of a class of conformal field theories (CFT) with or (nonlinear) superconformal symmetry. Generalising the spinon basis of the WZW theories, we introduce supersymmetric spinons , which form a representation of the supersymmetry algebra. In each case, we show how to construct a multi-spinon basis of the chiral CFT spectra. The multi-spinon states are labelled by a collection of (discrete) momenta. The state-content for given choice of is determined through a generalised exclusion principle, similar to Haldane's ‘motif’ rules for the theories. In the simplest case, which is the superconformal theory with central charge c = 1, we develop an algebraic framework similar to the Yangian symmetry of the theory. It includes an operator H2, akin to a CFT Haldane–Shastry Hamiltonian, which is diagonalised by multi-spinon states. In all cases studied, we obtain finite partition sums by capping the spinon-momenta to some finite value. For the superconformal CFTs, this finitisation precisely leads to the so-called Mk supersymmetric lattice models with characteristic order-k exclusion rules on the lattice. Finitising the c = 2 CFT with nonlinear superconformal symmetry similarly gives lattice model partition sums for spin-full Fermions with on-site and nearest neighbour exclusion.

Invader LNA: Efficient targeting of short double stranded DNA

Despite progress with triplex-forming oligonucleotides or helix-invading peptide nucleic acids (PNAs), there remains a need for probes facilitating sequence-unrestricted targeting of double stranded DNA (dsDNA) at physiologically relevant conditions. Invader LNA probes, i.e., DNA duplexes with "+1 interstrand zipper arrangements" of intercalator-functionalized 2'-amino-alpha-l-LNA monomers, are demonstrated herein to recognize short mixed sequence dsDNA targets. This approach, like pseudo-complementary PNA (pcPNA), relies on relative differences in stability between probe duplexes and the corresponding probe:target duplexes for generation of a favourable thermodynamic gradient. Unlike pcPNA, Invader LNA probes take advantage of the "nearest neighbour exclusion principle", i.e., intercalating units of Invader LNA monomers are poorly accommodated in probe duplexes but extraordinarily well tolerated in probe-target duplexes (DeltaT(m)/modification up to +11.5 degrees C). Recognition of isosequential dsDNA-targets occurs: a) at experimental temperatures much lower than the thermal denaturation temperatures (T(m)'s) of Invader LNAs or dsDNA-targets, b) at a wide range of ionic strengths, and c) with good mismatch discrimination. Recognition of dsDNA is monitored in real-time using inherent pyrene-pyrene excimer signals of Invader LNA probes, which provides insights into reaction kinetics and enables rational design of probes. These properties render Invader LNAs as promising probes for biomedical applications entailing sequence-unrestricted recognition of dsDNA.

Cluster dynamics and universality of Ising lattice gases

Lattice gases with nearest-neighbour exclusion are studied by means of Monte Carlo simulations with an efficient cluster algorithm. The critical dynamics is consistent with a dynamical exponent z=0 in the case of Wolff-like cluster updates for square and simple-cubic lattices in the studied range of lattice sizes. We find the critical activity z c =0.72020(4) for the body-centred cubic lattice. The critical exponents y h =2.475(8) and y t =1.61(6) disagree with an earlier study, but they do agree with the known values for the three-dimensional Ising universality class.

The simple-cubic lattice gas with nearest-neighbour exclusion: Ising universality

The lattice gas with nearest neighbour-exclusion on the simple cubic lattice is studied by means of statistically accurate Monte Carlo simulations with an efficient cluster algorithm. Our results for critical exponents are y h = 2.47(1) and y t = 1.60(2). These results agree well with the three-dimensional Ising universality class. We explain the discrepancy with an earlier study. The critical activity is z c = 1.0559 (1). The size distribution of the clusters indicates that the percolation threshold of the cluster formation process of the Monte Carlo algorithm coincides with the critical point.

Universality in the three-dimensional hard-sphere lattice gas

We perform Monte Carlo simulations of the hard-sphere lattice gas on the body-centred cubic lattice with nearest-neighbour exclusion. We get the critical exponents, ß/ ν = 0.311(8) and γ/ ν = 2.38(2), where β, γ, and ν are the critical exponents of the staggered density, the staggered compressibility, and the correlation length, respectively. The values of the hard-sphere lattice gas on the simple cubic lattice agree with them but those of the three-dimensional Ising model do not. This supports that the hard-sphere lattice gas does not fall into the Ising universality class in three dimensions.

Critical activity of the hard-sphere lattice gas on the body-centred cubic lattice

This is the first Monte Carlo study of the hard-sphere lattice gas with nearest neighbour exclusion on the body-centred cubic lattice. We estimate the critical activity to be 0.7223±0.0003. This result confirms that there is a re-entrant phase transition of an antiferromagnetic Ising model in an external field and a Blume-Emery-Griffiths model on the body-centred cubic lattice.

Critical phenomena of the hard-sphere lattice gas on the simple cubic lattice

We study the critical phenomena of the hard-sphere lattice gas on the simple cubic lattice with nearest neighbour exclusion by the Monte Carlo method. We get the critical exponents β/ v = 0.313 (9) and γ/ v = 2.37 (2), where β is the critical exponent for the staggered density, γ for the staggered compressibility, and v for the correlation length.

Absence of re-entrant phase transition of the antiferromagnetic Ising model on the simple cubic lattice: Monte Carlo study of the hard-sphere lattice gas

We perform Monte Carlo simulations of the hard-sphere lattice gas on the simple cubic lattice with nearest neighbour exclusion. The critical activity is estimated, z c = 1.0588 ± 0.0003. Using a relation between the hard-sphere lattice gas and the antiferromagnetic Ising model in an external magnetic field, we conclude that there is no re-entrant phase transition of the latter on the simple cubic lattice.

Exact bounds from a new series-expansion method for random sequential adsorption

We present a new series-expansion method for the analysis of the covering fraction Theta in a random sequential adsorption process with nearest-neighbour exclusion on a lattice. It is the first method to yield sequences of increasing lower bounds and decreasing upper bounds on Theta . It is illustrated by numerical calculations for the hexagonal lattice.

Equilibrium crystal shape of hard squares with diagonal attractions

The author exactly calculates the anisotropic interfacial tension of a square lattice gas model with nearest-neighbour exclusion and next-nearest-neighbour attractions. This is achieved by a method which introduces the shift operator into the standard transfer matrix argument. From the calculated anisotropic interfacial tension the equilibrium crystal shape (ECS) is derived by the use of the Wulff construction. The ECS is a closed curve in the X-Y plane, represented as cosh( Lambda (X+Y)/kBT)+A3cosh( Lambda (X-Y)/kBT)+A4/2=0 with a scale factor Lambda and constants A3,A4. He argues that this shape is a universal one which appears as the ECSS of a wide class of models.

Long‐Time Behaviour of the Weakly Asymmetric Exclusion Process and the BURGERS Equation without Viscosity

AbstractWe investigate macroscopic properties of the onedimensional weakly asymmetric nearest neighbour exclusion process for long times. We show that the particle system can be approximated by the solution of a discrete version of the viscid BURGERS equation, but with random initial datum. In a larger space scale we show the convergence to a deterministic solution of the BURGERS equation without viscosity.

A Central Limit Theorem for the Weakly Asymmetric Simple Exclusion Process

AbstractWe consider the one‐dimensional weakly asymmetric nearest neighbour exclusion process and study, in macroscopic space‐time coordinates, the fluctuations of the associated density field around the solution of the nonlinear BURGERS equation with viscosity. We show that this fluctuations converge to a generalized ORNSTEIN‐UHLENBECK process, the drift term of which can be obtained by linearization of the BURGERS equation. Our approach is based on a nonlinear transformation of the exclusion process.

Travelling waves and long-time behaviour of the weakly asymmetric exclusion process

We consider the one-dimensional weakly asymmetric nearest neighbour exclusion process and study its macroscopic behaviour on a longer time scale than that for which the deterministic approximation by the Burgers equation holds. We show that this long-time behaviour is completely determined by the initial particle configuration, and does not depend on the randomness of the evolution. Moreover, we examine in detail a special case for which a travelling wave is observed with stable profile but randomly fluctuating space location.

Monte Carlo study of static correlations in lattice gases with nearest and next nearest neighbour exclusion

Monte Carlo simulation and the mean-spherical model have been used to obtain static correlations in a hard-square lattice gas. The results indicate a second-order transition at the critical wave-vector q c= π a(1, 1) when nearest neighbours are excluded. The chemical potential, calculated by the Widom method, and the pair distribution function, however, indicate no order/disorder transition when next nearest neighbours are excluded.

Hard squares with diagonal attractions

The authors complete the solution of the square lattice gas with nearest neighbour exclusion and attractive next-nearest neighbour (diagonal) interactions on the special surface corresponding to regimes III and IV of the generalised hard hexagon model. The interfacial tension, correlation length and sublattice density difference are calculated throughout these regimes by obtaining the eigenvalues of the row-to-row and corner transfer matrices. The associated critical exponents are found to be mu =v=5/4, beta =3/32 in regime III and mu '=v'=5/2, beta '=1/4 in regime IV. In particular, their results confirm the recent proposal by Huse that regime III is the first-order coexistence surface (separating the disordered fluid phase from the square ordered solid phases) and that the regime III/regime IV boundary is a line of tricritical points.

Multiphase behaviour of the plane quadratic lattice gas with nearest-neighbour exclusion and next-nearest-neighbour finite interaction

The plane quadratic lattice gas with nearest-neighbour exclusion and next-nearest-neighbour finite interaction is considered in the framework of the double-site and single-square approximations of the cluster variation method and in the branched lattice approximation. In addition to the disordered and hard-core-ordered phases only one extra phase is shown to exist which arises at low temperatures near the half-maximum density. This phase which is due to the next-nearest-neighbour repulsion exhibits both first- and second-order transitions to the disordered phase.

A comparison of the base-pair specificities of three phenanthridine drugs sing solution spectroscopy

1. 1. The absorption spectrum of three phenanthridine drugs (ethidium, dimidium and prothidium bromide) bound to natural DNAs of differing G-C content were obtained using a novel mixing scheme and analysed according to the excluded site binding model. 2. 2. Ethidium bromide shows a strong G-C specificity at low binding ratios, expecially at low ionic concentration. 3. 3. Dimidium bromide shows a less strong G-C specificity. 4. 4. For both drugs, the binding site size reflects a situation close to nearest-neighbour exclusion. 5. 5. Prothidium shows no specificity in its binding. The binding modes are different than for the other two phenanthridines, and it is suggested that the primary mode is “sideways” intercalation.

A computer-simulation study of the behaviour of the Haven ratio near order/disorder transitions in highly defective solids

Abstract Monte Carlo results are presented for the Haven ratio in the square planar lattice gas with nearest-neighbour exclusion and the square planar lattice gas with nearest-neighbour repulsion and next-nearest-neighbour attraction with the latter at a temperature less than the critical temperature at 50% occupation. Unlike the simple cubic athermal lattice gas studied earlier, a minimum in Hr occurs at concentrations less than the critical concentration because of a percolation requirement. The lattice gas with finite interactions shows turning points at the phase transitions with apparent accompanying changes in the percolation behaviour and diffusion mechanism.

Existence of an ordered phase for the repulsive lattice gas on the FCC lattice

It is proven by Peierls' argument in connection with reflection positivity that the lattice gas on the FCC lattice with nearest-neighbour repulsion (with interaction energy a) exists in an ordered state at low enough temperature provided the chemical potential, mu , satisfies 0< mu <4a, 4a< mu <8a or 8a< mu <12a. This result immediately carries over to the antiferromagnetic Ising model and the lattice gas with nearest-neighbour exclusion on the FCC lattice, both of which will also exist in an ordered state under suitable circumstances. In particular, the existence of a phase transition at zero magnetic field is confirmed.