Two-state Method Research Articles

A Two-State Dynamic Decomposition-Based Evolutionary Algorithm for Handling Many-Objective Optimization Problems

Decomposition-based many-objective evolutionary algorithms (D-MaOEAs) are brilliant at keeping population diversity for predefined reference vectors or points. However, studies indicate that the performance of an D-MaOEA strongly depends on the similarity between the shape of the reference vectors (points) and that of the PF (a set of Pareto-optimal solutions symbolizing balance among objectives of many-objective optimization problems) of the many-objective problem (MaOP). Generally, MaOPs with expected PFs are not realistic. Consequently, the inevitable weak similarity results in many inactive subspaces, creating huge difficulties for maintaining diversity. To address these issues, we propose a two-state method to judge the decomposition status according to the number of inactive reference vectors. Then, two novel reference vector adjustment strategies, set as parts of the environmental selection approach, are tailored for the two states to delete inactive reference vectors and add new active reference vectors, respectively, in order to ensure that the reference vectors are as close as possible to the PF of the optimization problem. Based on the above strategies and an efficient convergence performance indicator, an active reference vector-based two-state dynamic decomposition-base MaOEA, referred to as ART-DMaOEA, is developed in this paper. Extensive experiments were conducted on ART-DMaOEA and five state-of-the-art MaOEAs on MaF1-MaF9 and WFG1-WFG9, and the comparative results show that ART-DMaOEA has the most competitive overall performance.

Estimation of Sensible and Latent Heat Fluxes of an Isolated Tree in Japanese Summer

Considering that the characteristics of the heat balance between an isolated tree and the urban atmosphere have not yet been sufficiently clarified, we quantify both the sensible heat flux ($$ H_{T} $$) and latent heat flux ($$ lE_{T} $$) to and from an isolated Z. Serrata in the Japanese summer. To estimate the whole-tree transpiration rate (ET) and $$ lE_{T} $$ values, we apply a previously developed method using a weighing lysimeter. To estimate the boundary-layer heat conductance ($$ g_{hT} $$) of the total leaf area of the tree crown and the sensible heat flux ($$ H_{T} $$), we apply a scaling-up approach using the heat-balance two-state (HB-TS) method, which previously only targeted single leaves, to the tree crown. Two sample trees with similar crown shape and total leaf area are selected for the HB-TS method but under different irrigation conditions, and $$ g_{hT} $$ is estimated. The ET values of the tree change three times during the dry-down experiment (during which time irrigation was halted). We also compare HT and lET values between two different days under different irrigation and soil–water conditions. The most important result from this comparison is that the tendencies of HT and lET were reversed on these days, and the Bowen ratio ($$ \beta = H_{T} /lE_{T} $$) dramatically varies between 0.29 and 2.2. These results indicate that the Bowen ratio of isolated trees at urban sites can vary between the previously reported values for forest sites and those for artificial urban sites within a short period, owing to urban-unique conditions (e.g., limited water supply and rooting space, and artificial sealing).

Indoors Positioning Based on Spatial Relationships in Locality Description

Spatial relationships exist in our daily communication and provide many locality clues, but minimal attention has been devoted to positioning localities indoors with spatial relationships extracted from locality descriptions. Locality description generally contains spatial relationships (i.e., topological, distance, and direction relations) and reference objects (ROs). For locality description positioning, distance and direction relation convey more clue than topology and combined together can provide much clue to positioning. Explicit and implicit features are inherent characteristics of locality descriptions. Based on the analysis of locality descriptions, a classification scheme of indoor locality descriptions is provided. To address the positioning locality with spatial relationships, we propose a two-state method. First, the located region is obtained according to the fuzzy region of spatial relations in locality description. Second, the probability distribution is determined, which is a joint probability function that consists of relative direction and distance (quantitative or qualitative distance) membership functions. The relative direction membership function is conducted based on human’s direction cognition is related to angular information. The trapezoid quantitative distance membership function is based on indoor cognitive experiment. The qualitative distance membership function for indoor ROs is based on minimum Euclidean distance and stolen area. From the cognition and computation perspectives, the visible boundary met some restrictions is provided and a sampling method is defined. To obtain the unique positioning locality, a principle is proposed. We evaluate our method by conducting an indoor cognitive experiment and demonstrate that a positioning accuracy of 3.50 m can be achieved with semantically derived spatial relationships.

Development of a high throughput micro-heater array with controllable temperature for each heating unit

In this paper, we propose a high throughput micro-heater array in which the temperature of each heating unit can be controlled separately and independently. First, a micro-heater with 3-layer structure is designed and the optimization is made to simplify the wire connection within the micro-heater array to compact the device size. For the device fabrication, the 3 × 3 micro-heater array is fabricated using MEMS fabrication technology. Furthermore, a novel two-state method is developed to control the heating pattern of the device with outstanding advantages. With this method, heating units in the array can be selectively heated and each unit can be well-controlled simultaneously under different temperatures. Measurement results demonstrate the good performance of the micro-heater unit and functionality of the micro-heater array device, which can be applied to versatile fields with a promising future.

Error-disturbance uncertainty relations studied in neutron optics

Heisenberg's uncertainty principle is probably the most famous statement of quantum physics and its essential aspects are well described by a formulations in terms of standard deviations. However, a naive Heisenberg-type error-disturbance relation is not valid. An alternative universally valid relation was derived by Ozawa in 2003. Though universally valid Ozawa's relation is not optimal. Recently, Branciard has derived a tight error-disturbance uncertainty relation (EDUR), describing the optimal trade-off between error and disturbance. Here, we report a neutron-optical experiment that records the error of a spin-component measurement, as well as the disturbance caused on another spin-component to test EDURs. We demonstrate that Heisenberg's original EDUR is violated, and the Ozawa's and Branciard's EDURs are valid in a wide range of experimental parameters, applying a new measurement procedure referred to as two-state method.

Time-symmetrized description of nonunitary time asymmetric quantum evolution

We discuss how systems which evolve manifestly asymmetrically in time can be described within the framework of the time-symmetrized quantum mechanics. An obvious case of asymmetry arises when a pure state evolves into a mixed state via effectively non-unitary evolution. A two-state method for finding the intermediate probability in postselected systems under such evolution is developed and the time-symmetry aspects of the method are explicitly considered. A specific feature is the existence of the so-called second scenario in which the state originating from the postselection measurement evolves under different evolution superoperator than the state from the preselection measurement. The evolution of the second scenario is explicitly defined. We illustrate the method with two characteristic examples: the spontaneous deexcitation of atoms and the systems approaching thermal equilibrium. We consider the systems with two energy levels and calculate the time-symmetrized probability of finding the system in excited state, under general preselection and postselection conditions. The consequences of the asymmetry of the time evolution on this probability are discussed. It is demonstrated that the arrow of time can be reconstructed in some special cases of postselected systems, while, for a general system, this is not the case.

Comment on “Ground-state fragmentation phase transition for attractive bosons in anisotropic traps”

In a recent article [Phys. Rev. A 88, 063641 (2013)], Cizek and Kasevich claimed that quantum fragmentation occurs in the metastable state of a Bose-Einstein condensate with an attractive interaction confined in an elongated harmonic potential. This result was obtained using the two-state Gaussian variational method. However, modified methods show that no fragmentation occurs for the parameters used by Cizek and Kasevich.

Intramolecular Electronic Couplings in Class II/III Organic Mixed-Valence Systems of Bis(1,4-dimethoxybenzene)

The intramolecular electronic couplings in organic mixed-valence systems [D-(ph)(n)-D](•+) (D = 2,5-dimethoxy-4-methylphenyl, n = 0, 1, and 2) are calculated by dominantly using density functional theory to investigate their dependence of functionals. Since these systems have the property that the charge is from localization to delocalization, the optimized structures are sensitive to the functionals. The geometric optimizations show that CAM-B3LYP and ωB97X-D functionals are good choices for delocalized systems and LC-ωPBE and M06HF are suitable for the systems from charge almost localization to localization. The calculations of electronic couplings demonstrate that the pure functional generally underestimates the electronic couplings whereas the pure HF overestimates them. Furthermore, the electronic couplings from the conventional generalized Mulliken-Hush method are very sensitive to the HF component in functionals, which makes it a challenge to accurately estimate the values. A new reduced two-state method is thus proposed to overcome the deficiency, and the obtained electronic couplings are less sensitive to the ω value in LC-ω PBE functional and they are also consistent with the experimental data.

Electronic coupling for charge transfer in donor–bridge–acceptor systems. Performance of the two-state FCD model

Electronic coupling is a key parameter that determines the rate of electron transfer reactions and electrical conductivity of molecular wires. To examine the performance of a two-state approach based on the orthogonal transformation of adiabatic states to diabatic states, we compare the effective donor-acceptor coupling V(DA) computed with three different approaches in model donor-bridge-acceptor (D-B-A) systems. It is found that V(DA) derived with the two-state method accounts properly for both the direct and superexchange interactions. The approach becomes, however, less accurate with the increasing energy difference of the donor and acceptor states. We suggest a simple diagnostic to identify the situation when the estimated coupling might be inaccurate and consider how to improve the performance of the two-state scheme in such a case.

Electron Paramagnetic Resonance Spectroscopy of Bis(triarylamine) Paracyclophanes as Model Compounds for the Intermolecular Charge-Transfer in Solid State Materials for Optoelectronic Applications

A set of seven bis(triarylamine) mixed-valence radical cations with different bridging moieties were investigated by temperature-dependent electron paramagnetic resonance (EPR) spectroscopy in methylene chloride and ortho-dichlorobenzene to evaluate the thermal electron transfer rate constants. The bridges used comprise [2,2]paracyclophane and [3,3]paracyclophane as well as fully conjugated phenylene spacers. The cyclophanes serve as model structures for studying the intermolecular electron transfer in solid state materials. The activation barriers derived by EPR measurements are compared with those estimated by the two-state Marcus−Hush analysis as well as by its extension to three states. Both methods gave good agreement with the EPR data, the three-state method being slightly better than the two-state method. On the basis of the choice of the different bridging groups, our study shows that the bridge can have a significant influence on the internal reorganization energy. [2,2]Paracyclophane and [3,3]paracyclophane bridge units show practically the same electronic coupling and thermal barrier. Conjugated bridges have thermal rates about 1 order of magnitude larger than the radical cations with broken conjugation. These two aspects show that in solid state materials triarylamines drawn close to their van der Waals radii may exhibit efficient coupling and rate constants by only 1 order of magnitude smaller than fully conjugated materials.

Formation of antihydrogen in the ground state

Cross sections for antihydrogen formation in the ground state for the process [Formula: see text] + Ps(nlm) → [Formula: see text](1s) + e– have been calculated using charge conjugation and time reversal invariance. Calculations are based on a two-state approximation method, used by the author earlier for positron–hydrogen charge -exchange process (e+ – H → Ps(nlm) + p). Cross-section results are reported in the intermediate- and high-energy region (20 keV – 500 keV). PACS No.: 36.10.Dr

Modeling kinetic adsorption in porous media by a two-state random walk practical method

Modeling kinetic adsorption in porous media by a two-state random walk practical method

Quantum state reconstruction for strongly excited Rydberg atom wave packets via a two-state Ramsey fringe inversion method

We show that wave-packet interference techniques can reconstruct the quantum state of wave packets excited by strong laser pulses. The measurement may be accomplished even when the strength of the excitation is sufficient to significantly deplete the ground state. The probe of the wave packet can still remain perturbative. An inversion algorithm is also developed that is a generalization of the standard Ramsey fringe probe of a wave packet. The normalized sums and differences of the populations of two of the Rydberg states display Ramsey fringes and from these fringes the relative phase between these two states can be found. The algorithm offers advantages in efficiency over previous interferometric algorithms. The algorithm is not sensitive to the precise nature of the distribution of the phase between the pump and probe pulses.

CHARGE TRANSFER FOR PROTON AND α PARTICLE COLLIDING WITH HELIUM ATOM AT INTERMEDIATE ENERGIES

Charge transfer processes for double-electron colliding systems H++He and He2++He have been studied by using the asymptotic two-state atomic expansion method developed recently. Our results for the cross sections of electron capture are in good agreement with those given by the boundary-corrected first-order Born (B1B) approximation and experimental data in high-intermediate energies, and in the low-intermediate energies the present results are better than those obtained by the B1B approximation. Finally, we point out that the reason that capture cross sections predicted by first-order perturbation theory are in poor agreement with experimental data.

Hydration Model for the Energy Barrier in Self-Exchange Electron Transfer Reactions in Solution

This paper presents two new theoretical models for accurately determining activation energy and reorganization energy for an electron exchange reaction in solution. The hydration process of an ion is considered and two accurate potential functions (Morse function and anharmonic oscillator potential function) are defined in terms of experimental spectroscopic and hydration thermodynamic data. These functions are then used to depict the energy dependence of the reacting system on the separation between the central ion and the innersphere water molecules and the solvent reorganization. The activation energy and reorganization energy are obtained in terms of the proposed activation and reorganization models and the hydration potential functions. The experimental activation energy is corrected by taking into account the actual electronic transmission coefficient. The slopes of the potential energy surfaces are obtained from the proposed accurate hydration potential functions, and the coupling matrix element is determined by the two-state model and numerical integral method over the perturbed d-electron double-zeta Slater-type wave functions. The theoretical values of the activation energy are compared with the experimental values, and the relationship between the activation energy and the reorganization energy is tested. The applicability of these models are also discussed.

Differential cross sections for elastic and inelastic positron scattering from alkali atoms

We have investigated positron scattering from the alkali atoms lithium, sodium, potassium and rubidium, focusing on the calculation of differential cross sections for elastic scattering and impact excitation. The results obtained with the two-state and five-state close-coupling method as well as the first-order distorted wave Born approximation are compared with each other and with some selected results for electron scattering. Numerical problems due to lack of, or numerically inaccurate, calculation of partial waves with large angular momenta are solved through semi-empirical fitting/extrapolation procedures.

Equilibrium charge distributions for B, C, N ions passing through solid and gaseous media

Abstract The equilibrium charge state distributions (ECSD) for fast B, C, N ions penetrating through solid and gaseous targets are investigated with atomic collision theories. For the electron-capture and -loss processes, the two-state atomic expansion method and the Born approximation are used respectively. With the increase of the ion velocity, the equilibrium mean charge becomes saturated and the distribution width becomes narrower. The numerical calculations for the ECSD are in good agreement with the experimental results.

Quasi-molecular binding corrections to the two-state atomic expansion method for electron capture at low energies

The two-centre, two-state atomic expansion method previously developed for calculating electron capture cross sections for ion-atom collisions at intermediate energies is generalised to the lower energy region. By replacing the asymptotic energy defect term between initial and final states of the atomic expansion theory by the difference of the corresponding quasi-molecular energies, the effect of transient molecule formation during the collision is partially accounted for. The increased quasi-molecular binding at small internuclear separation has the effect of reducing electron capture cross sections at lower incident energies; the cross sections thus calculated show improved agreement with experimental data.

SiK-shell ionization and electron transfer cross sections: Solid targets

The Si K x-ray production cross sections for F/sup q/+(q = 3--9) ion impact in the energy range of 0.4--2.2 MeV/amu are determined in the limit of a vanishingly thin target from the observed target thickness dependence of the x-ray yields. The ionization cross sections are deduced from the measured x-ray production cross sections using an average fluorescence yield (omega-tilde = 1.5..omega../sub 0/, where ..omega../sub 0/ is the fluorescence yield for an atom with single K vacancy) determined from high-resolution x-ray spectra and configuration fluorescence yields. For F/sup q/+ (q < or = 6) ion impact, the measured ionization cross sections are compared with the plane-wave-Born-approximation prediction with and without the Coulomb deflection and increased-binding-energy effects. The Si K shell to F K shell electron-transfer cross sections are determined from the difference between the ionization cross sections for F/sup 9 +/ ions and those for F/sup q/+ ions (q < or = 6). The results are compared with the prediction based on the two-state atomic-expansion method and that based on the modified Oppenheimer-Brinkman-Kramers approximation. A comparison is also made between the Si solid-target measurements with those obtained for gaseous Ne and Ar gas targets. The solid-target and gas-target data aremore » consistent at 1.58 MeV/amu. Finally, from a comparison between the measured equilibrium x-ray yields and the calculated x-ray yields using the equilibrium charge distribution of projectiles after passing through foils, it is found that the projectiles have a considerably larger number of K-shell vacancies inside solids than after passing through solids at lower-impact energies.« less