Standard Optical Model Research Articles

Research on Black Smoke Detection and Class Evaluation Method for Ships Based on YOLOv5s-CMBI Multi-Feature Fusion

To enhance the real-time detection accuracy of ship exhaust plumes and further quantify the degree of darkness, this study proposes a multi-feature fusion approach that combines the YOLOv5s-CMBI algorithm for ship exhaust plume detection with the Ringerman Blackness-based grading method. Firstly, diverse datasets are integrated and a subset of the data is subjected to standard optical model aerosolization to form a dataset for ship exhaust plume detection. Subsequently, building upon the YOLOv5s architecture, the CBAM convolutional attention mechanism is incorporated to augment the network’s focus on ship exhaust plume regions while suppressing irrelevant information. Simultaneously, inspired by the BiFPN structure with weighted bidirectional feature pyramids, a lightweight network named Tiny-BiFPN is devised to enable multi-path feature fusion. The Adaptive Spatial Feature Fusion (ASFF) mechanism is introduced to counteract the impact of feature scale disparities. The EIoU_Loss is employed as the localization loss function to enhance both regression accuracy and convergence speed of the model. Lastly, leveraging the k-means clustering algorithm, color information is mined through histogram analysis to determine clustering centers. The Mahalanobis distance is used to compute sample similarity, and the Ringerman Blackness-based method is employed to categorize darkness levels. Ship exhaust plume grades are estimated by computing a weighted average grayscale ratio between the effective exhaust plume region and the background region. Experimental results reveal that the proposed algorithm achieves improvements of approximately 3.8% in detection accuracy, 5.7% in recall rate, and 4.6% in mean average precision (mAP0.5) compared to the original model. The accuracy of ship exhaust plume darkness grading attains 92.1%. The methodology presented in this study holds significant implications for the establishment and application of future ship exhaust plume monitoring mechanisms.

Scattering processes of helium nuclides on nuclei 28Si

Experimental data on elastic and inelastic scattering of 50.5 MeV α-particles and 60 MeV 3He ions by 28Si nuclei were analyzed within the framework of the standard optical model of the nucleus, in which the effect of inelastic channels is taken into account by the phenomenological introduction of an imaginary absorbing part into the interaction potential between colliding nuclei. The optimal values of the internuclear interaction potential obtained as a result of the theoretical analysis were used to study the cross sections for inelastic scattering of helium ions with the excitation of the 1.78 and 4.61 MeV states of the nucleus under study. From the analysis by the channel coupling method, where the calculation was performed taking into account both elastic and inelastic channels, the value of the quadrupole deformation parameter for α-particles β2 = 0.37 and for 3He ions β2 = 0.49 was determined. Optimal agreement between the calculated values and experimental data was achieved by varying the parameters V, W, and β2. The found parameters agree with the previously obtained values from the scattering of protons, deuterons and α-particles. Taking into account only the quadrupole deformation extracted from the 0+ – 2+ bond, a good description of all three experimental data on elastic and inelastic scattering of the cross sections was achieved.

Focused and defocused retinal images with Bessel and axicon pupil functions.

Retinal image light distributions in a standard optical model of a diffraction-limited eye with round pupils are presented for several patterns of amplitude and phase modulation of the light admitted into the eye. Of special interest are circularly symmetrical configurations of truncated Bessel amplitude transmission functions, and of light subjected to axicon deviation. It is shown by several examples that this kind of beam shaping allows generation of retinal imagery, which can be more robust to defocus while maintaining minimal image degradation, and it points to situations of two separate zones simultaneously in sharp focus, several diopters apart.

I-V- Characteristics analysis of betavoltaic microbatteries using TCAD model

The complete analysis of I-V characteristics and set of basic parameters for betavoltaic silicon batteries under Nickel-63 irradiation in the temperature range from 213 to 330 K is carried out using a universal physical TCAD model. The standard TCAD optical generation model was adopted for simulation of electron-hole generation for beta particles irradiation. The pn-junction diode energy converters with real Gaussian doping profiles are considered. The simulated current-voltage characteristics of the 63Ni-Si betavoltaic elements are in good agreement with the measured characteristics.

Fraunhofer and refractive scattering of heavy ions in strong laser fields

Until recently the potential scattering of a charged particle in a laser field received attention exclusively in atomic physics. The differential cross-section of laser-assisted electron-atom collisions for n emitted or absorbed photons is provided by a simple law which casts the result as a product between the field-free value and the square of the Bessel function of order n with its argument containing the effect of the laser in a non-perturbative way. From the experimental standpoint, laser-assisted electron-atom collisions are important because they allow the observation of multiphoton effects even at moderate laser intensities. The aim of this study is to calculate the nucleus-nucleus differential cross section in the field of a strong laser with wavelengths in the optical domain such that the low-frequency approximation is fulfilled. We investigate the dependence of the n-photon differential cross-section on the intensity, photon energy and shape of the pulse for a projectile/target combination at a fixed collision energy which exhibits a superposition of Fraunhofer and refractive behavior. We also discuss the role of the laser perturbation on the near and farside decomposition in the angular distribution, an issue never discussed before in the literature. We apply a standard optical model approach to explain the experimental differential cross-section of the elastic scattering of 4He on 58Ni at a laboratory energy E = 139 MeV and resolve the corresponding farside/nearside (F/N) decomposition in the field-free case. We give an example of reaction in which Fraunhofer diffraction and refractive rainbow hump effects are easily recognized in the elastic angular distribution. Next, we apply the Kroll-Watson theorem, in order to determine the n -photon contributions to the cross-section for continuous-wave (cw) and modulated pulses. In the elastic scattering of heavy ions in a radiation field of low intensity, the amplitude drops by orders of magnitude with respect to the unperturbed case once the exchange of photons is initiated. For intensities approaching $I=10^{17}$ W/cm2 multiphoton effects become important. In the case of short laser pulses we conclude that the strength of n-photon contribution increases with the pulse duration.

An optical absorption model including absorber saturation

Usually, the calculation of the optical generation in solar cell simulations is based on the assumption of constant absorption coefficients. Under certain circumstances, however, the absorption coefficient may depend on the light intensity, for example, if the absorbing material suffers from optical saturation. In this work, we present a simple model taking into account a saturable absorber, which can be easily implemented in standard optical simulation models.

Low-energy nucleon-nucleus scattering within the energy density functional approach

The description of nucleons scattering off doubly closed-shell nuclei $^{16}\mathrm{O}$ and $^{208}\mathrm{Pb}$ at energies below 50 MeV is carried out in a fully self-consistent framework of the particle-vibration coupling approach. The applications are performed with commonly used Skyrme-type effective interactions. Nucleon-nucleus optical potentials are thus calculated without ad hoc adjusted parameters. These potentials are then solved with standard optical model codes (dwba98 in the present case). Empirical nucleon-nucleus elastic angular distributions are thus successfully reproduced.

Strong coupling effects in near-barrier heavy-ion elastic scattering

Accurate elastic scattering angular distribution data measured at bombarding energies just above the Coulomb barrier have shapes that can markedly differ from or be the same as the expected classical Fresnel scattering pattern depending on the structure of the projectile, the target or both. Examples are given such as 18O + 184W and 16O + 148, 152Sm, where the expected rise above Rutherford scattering due to Coulomb-nuclear interference is damped by coupling to the target excited states, and the extreme case of 11Li scattering, where coupling to the 9Li + n + n continuum leads to an elastic scattering shape that cannot be reproduced by any standard optical model parameter set. An early indication that the projectile structure can modify the elastic scattering angular distribution was the large vector analyzing powers observed in polarised 6Li scattering. The recent availability of high-quality 6He, 11Li and 11Be data provides further examples of the influence that coupling effects can have on elastic scattering. Conditions for strong projectile-target coupling effects are presented with special emphasis on the importance of the beam-target charge combination being large enough to bring about the strong coupling effects. Several measurements are proposed that can lead to further understanding of strong coupling effects by both inelastic excitation and nucleon transfer on near-barrier elastic scattering. A final note on the anomalous nature of 8B elastic scattering is presented as it possesses a more or less normal Fresnel scattering shape whereas one would a priori not expect this due to the very low breakup threshold of 8B . The special nature of 11Li is presented as it is predicted that no matter how far above the Coulomb barrier the elastic scattering is measured, its shape will not appear as Fresnel like whereas the elastic scattering of all other loosely bound nuclei studied to date should eventually do so as the incident energy is increased, making both 8B and 11Li truly “exotic”.

Modeling the impacts of calcite precipitation on the epilimnion of an ultraoligotrophic, hard-water lake

A mass-balance model of calcite precipitation was developed to investigate the interactions of the varied processes governing the generation and fate of calcite in lakes. The model was used in conjunction with data to assess the evolution and impact of calcite precipitation for calcareous, ultraoligotrophic Torch Lake, Michigan (USA). This lake is an ideal setting for implementation of a baseline modeling study of calcite precipitation where the physical drivers could be evaluated without being dominated, as in many systems, by biological processes. The model provides a representation of calcite precipitation with particulate surface area changing over time, and demonstrates that it is possible for the change in water clarity to be explained by calcite precipitation employing standard optical models. Using the mass balance model to quantify the roles of the various chemical, biological and physical processes interacting in the lake's epilimnion, it was shown that the seasonal temperature rise and air–water CO 2 exchange drive calcite precipitation much more than primary production for this ultraoligotrophic system.

Elastic scattering of 6He from 12C at 38.3 MeV/nucleon

The microscopic optical potential of nucleus-nucleus interaction is presented via a folding method with the isospin dependent complex nucleon-nuclear potential, which is first calculated in the framework of the Dirac–Bruecker–Hartree–Fock approach. The elastic scattering data of 6He at 229.8 MeV on 12C target are analyzed within the standard optical model. To take account of the breakup effect of 6He in the reaction an enhancing factor 3 on the imaginary potential is introduced. The calculated 6He+12C elastic scattering differential cross section is in good agreement with the experimental data. Comparisons with results in the double-folded model based on the M3Y nucleon-nucleon effective interaction and the few the body Glauber-model calculations are discussed. Our parameter free model should be of value in the description of nucleus-nucleus scattering, especially unstable nucleus-nucleus systems.

Microscopic optical potential of nucleus–nucleus elastic scattering

Microscopic optical potential of nucleus–nucleus interaction is presented by a folding method with the isospin-dependent complex nucleon–nucleus optical potential, which is calculated in the framework of the Dirac–Bruecker–Hartree–Fock approach. A local density and improved local density approximations are adopted to make the potentials in nuclear matter relevant to finite nuclei. The 4He scattering off 12C at various energies E< 200 MeV are studied first. Then the elastic scattering data of 6He at 229.8 MeV on 12C target are analyzed within the standard optical model. To take account of the breakup effect of 6He in the reaction a phenomenological, large enhancing factor on the imaginary potential is introduced by hand. The calculated 6He+12C elastic scattering differential cross section is in reasonable agreement with the experimental data. Meanwhile comparisons with results in the double-folded model based on M3Y nucleon–nucleon effective interaction and the few body Glauber-model calculations are discussed. Our model should be of value in the description of the nucleus–nucleus scattering, especially unstable nucleus–nucleus systems.

Structural evolution of Co/Cu nanostructures under 1 MeV ion-beam irradiation

Co/Cu multilayers with composition wavelength ranging from 2 to 10 nm have been deposited and irradiated at various doses from 1×1014 to 3×1016 ions/cm2 using 1 MeV Si+ ions. The ion-beam-induced variation in structural properties such as interfacial mixing, interface roughness, crystallographic texture, and grain size, are characterized by a variety of x-ray scattering techniques. Irradiating Co/Cu multilayers generate metastable Co–Cu alloys whose electrical and magnetic properties have been found to be very similar to the Co–Cu alloys fabricated by other nonequilibrium methods. Fitting to the low-angle x-ray reflectivity spectra using a standard optical model yields a mixing efficiency comparable to the prediction of a ballistic ion-beam mixing model, and interfacial mixing widths consistent with the values estimated from saturation magnetization measurements.

Failure of Standard Optical Models to Reproduce Neutron Total Cross Section Differences in the W Isotopes

Recently cross section differences among the isotopes 182, 184, 186W have been measured as part of a study of total cross sections in the 5–560 MeV energy range.1) These measurements show oscillations up to 150 mb between 5 and 100 MeV. Spherical and deformed phenomenological optical potentials with typical radial and isospin dependences show very small oscillations, in disagreement with the data. In a simple Ramsauer model, 2–4) this discrepancy can be traced to a cancellation between radial and isospin effects. Understanding this problem requires a more detailed model that incorporates a realistic description of the neutron and proton density distributions. This has been done with results of Hartree-Fock-Bogolyubov calculations using the Gogny force, together with a microscopic folding model employing a modification5,6) of the JLM potential as an effective interaction. This treatment yields a satisfactory interpretation of the observed total cross section differences.

MeV Si + irradiation of Ni/Fe multilayers: structural, transport and magnetic properties

The modification of the structural, transport and magnetic properties of Fe(28 Å)/Ni(85 Å) multilayers on 1-MeV Si + irradiation at low temperature (77 K) has been studied as a function of dose. The as-deposited multilayers exhibit a strong Ni(111)/Fe(110) texture with sharp interfaces. Upon irradiation, progressive intermixing at the interfaces is clearly observed in the low-angle X-ray reflectivity and quantified by fitting the data with a standard optical model incorporating interface roughness, intermixing and individual layer thickness fluctuations. Simultaneously, the average grain size gradually increases from ∼170 to ∼250 Å with increasing ion dose up to 3×10 16 ions cm −2. These changes lead to an increase in the anisotropic magnetoresistance from ∼1.4% in the as-deposited sample to ∼1.8% after irradiation with a dose of 10 16 ions cm −2, and to the establishment of an in-plane easy axis for the magnetization. The effect of ion bombardment on the transport properties are explained using a model based on the Boltzmann equation incorporating the intermixing characteristics determined from the quantitative X-ray analyses.

Study of diffractive and refractive structure in the elastic [formula omitted]O [formula omitted]O scattering at incident energies ranging from 124 to 1120 MeV

The experimental data on elastic 16 O + 16 O scattering at incident energies ranging from 124 to 1120 MeV have been analyzed within the standard optical model (OM), using either the phenomenological (Woods-Saxon squared) potential or that calculated within the double-folding model for the real part of the optical potential. Structure of the elastic cross sections at smallest scattering angles was found to be of a pure diffractive nature, which enabled a consistent check of the absolute normalization of the elastic data under study. The OM analysis shows unambiguously the evolution of the refractive scattering pattern in the 16 O + 16 O system over this energy range. The large angle region of the data is dominated by the refractive far-side scattering. The oscillating Airy structure can be consistently described by a set of optical potentials with the real part given by the folding model and a weak absorptive imaginary potential.

Born and Markov approximations for atom lasers

We discuss the use of the Born and Markov approximations in describing the dynamics of an atom laser. In particular, we investigate the applicability of the quantum optical Born-Markov master equation for describing output coupling. We derive conditions based on the atomic reservoir, and atom dispersion relations for when the Born-Markov approximations are valid and discuss parameter regimes where these approximations fail in our atom laser model. Differences between the standard optical laser model and the atom laser are due to a combination of factors, including the parameter regimes in which a typical atom laser would operate, the different reservoir state which is appropriate for atoms, and the different dispersion relations between atoms and photons. We present results based on an exact method in the regimes in which the Born-Markov approximation fails. The exact solutions in some experimentally relavent parameter regimes give non-exponential loss of atoms from a cavity.

Modified three-body full-folding optical model potential.

The optical model potential for nucleon elastic scattering is investigated within the context of a three-body model. It is shown that the standard full-folding optical model potential is obtained as a special case of an approximate solution to such a three-body problem. A new full-folding-type optical model potential together with its corresponding factorized t\ensuremath{\rho} version are then obtained in the above three-body picture under some plausible approximations. \textcopyright{} 1996 The American Physical Society.

Nucleon- alpha -particle interactions from inversion of scattering phase shifts.

Scattering amplitudes have been extracted from (elastic scattering) neutron-alpha ({ital n}-{alpha}) differential cross sections below threshold using the constraint that the scattering function is unitary. Real phase shifts have been obtained therefrom. A modification to the Newton iteration method has been used to solve the nonlinear equation that specifies the phase of the scattering amplitude in terms of the complete (0 to 180{degree}) cross section since the condition for a unique and convergent solution by an exact iterated fixed point method, the {open_quote}{open_quote}Martin{close_quote}{close_quote} condition, is not satisfied. The results compare well with those found using standard optical model search procedures. Those optical model phase shifts, from both {ital n}-{alpha} and {ital p}-{alpha} (proton-alpha) calculations in which spin-orbit effects were included, were used in the second phase of this study, namely to determine the scattering potentials by inversion of that phase shift data. A modified Newton-Sabatier scheme to solve the inverse scattering problem has been used to obtain inversion potentials (both central and spin orbit) for nucleon energies in the range 1 to 24 MeV. The inversion interactions differ noticeably from the Woods-Saxon forms used to give the input phase shifts. Not only do those inversion potentials when used in Schr{umltmore » o}dinger equations reproduce the starting phase shifts but they are also very smooth, decay rapidly, and are as feasible as the optical model potentials of others to be the local form for interactions deduced by folding realistic two-nucleon {ital g} matrices with the density matrix elements of the {alpha} particle. {copyright} {ital 1996 The American Physical Society.}« less

Optical interference in second-harmonic generation from a metal surface with molecular adlayers

A strong oscillation pattern was observed in optical second-harmonic generation (SHG) at a Ag(111) surface under pyridine adlayers with variable thickness. This oscillation appears only when s-, but not p-, polarized fundamental light is used. This effect is attributed to the modulation of the radiation efficiency of the fundamental light penetrating into the Ag bulk and of the second-harmonic light radiating out to the vacuum by pyridine overlayers through optical interference. A standard optical interference model has been developed to quantitatively analyze the oscillation patterns and determine the adlayer thickness. It was found that at 90 K the pyridine overlayer growth rate is 1.4 Å per Langmuir exposure.

Optical absorption in dipolar aggregates with a biological application

Based on a two-dimensional description of interacting dipoles and a standard optical effective medium model we estimate structural properties of bacteriochlorophyll c in chlorosome aggregates of Chloroflexus bacteria. The main aim is to see what detailed structural information one can get out of an optical experiment. The measured optical spectrum turns out to be compatible with a distribution of aggregated pigment molecules approximately 9 Å apart from each other. Their interaction is responsible for the red-shift in peak position. A more random distribution of the aggregates in turn gives a broader and slightly asymmetric line shape. These results are in line with available structural determinations using other methods.