Forbidden States Research Articles

Supervisor Synthesis for Petri Nets With Uncontrollable and Unobservable Transitions

This paper focuses on designing event feedback supervisors to enforce control specifications on Petri nets with uncontrollable and unobservable transitions. For each observation, the supervisor is able to select some controllable transitions to disable such that the system never reaches illegal markings. Two different methods are given to design such a supervisor. The first method computes the control policy by solving some integer linear programming problems, while the second one designs supervisors by taking advantage of the structural properties of a class of Petri nets. The computational efficiencies of these two methods increase successively at the expense of their application scopes. Two examples are given to illustrate the proposed methods, respectively. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —The motivation of this paper consists in ensuring the behavior of a manufacturing system within a given legal behavior. The typical task for a designer is to design a supervisor to restrict that the system never reaches a forbidden state under limited control and observation ability. To this end, this paper proposes two different methods to design such a supervisor. The first one needs to solve integer linear programming problems, while the second one is based on the structural analysis of a special class of systems. It should be noted that although the application scope of the first method is wider, the second method has higher computational efficiency. Therefore, the suitable method can be chosen in accordance with the specific application scenario, which is significant and useful to manufacturing engineers.

Astrophysical S-factor and reaction rate for 15N(p,γ)16O within the modified potential cluster model* *Supported by the Ministry of Science and Higher Education of the Republic of Kazakhstan (AP09259174)

We study radiative capture on the ground state of 16O at stellar energies within the framework of a modified potential cluster model (MPCM) with forbidden states, including low-lying resonances. The investigation of the 15N( )16O reaction includes the consideration of resonances due to transitions and the contribution of the scattering wave in the p + 15N channel due to the transition. We calculated the astrophysical low-energy S-factor, and the extrapolated turned out to be within 34.7−40.4 keV·b. The important role of the asymptotic constant (AC) for the 15N( )16O process with interfering (312) and (962) resonances is elucidated. A comparison of our calculation for the S-factor with existing experimental and theoretical data is addressed, and a reasonable agreement is found. The reaction rate is calculated and compared with the existing rates. It has negligible dependence on the variation of AC but shows a strong impact of the interference of (312) and (962) resonances in reference to the CNO Gamow windows, especially at low temperatures. We estimate the contribution of cascade transitions to the reaction rate based on the exclusive experimental data from Phys. Rev. C. 85, 065810 (2012). The reaction rate enhancement due to the cascade transitions is observed from and reaches the maximum factor ~ 1.3 at . We present the Gamow energy window and a comparison of rates for radiative proton capture reactions 12N( )13O, 13N( ) 14O, 14N( )15O, and 15N( )16O obtained in the framework of the MPCM and provide the temperature windows, prevalence, and significance of each process.

Nonequilibrium Schwinger-Keldysh formalism for density matrix states: Analytic properties and implications in cosmology

Motivated by cosmological Hartle-Hawking and microcanonical density matrix prescriptions for the quantum state of the Universe we develop a Schwinger-Keldysh in-in formalism for generic nonequilibrium dynamical systems with the initial density matrix. We build the generating functional of in-in Green’s functions and expectation values for a generic density matrix of the Gaussian type and show that the requirement of particle interpretation selects a distinguished set of positive/negative frequency basis functions of the wave operator of the theory, which is determined by the density matrix parameters. Then we consider a special case of the density matrix determined by the Euclidean path integral of the theory, which in the cosmological context can be considered as a generalization of the no-boundary pure state to the case of the microcanonical ensemble, and show that in view of a special reflection symmetry its Wightman Green’s functions satisfy Kubo-Martin-Schwinger periodicity conditions which hold despite the nonequilibrium and nonstationary nature of the physical setup. Rich analyticity structure in the complex plane of the time variable reveals the combined Euclidean-Lorentzian evolution of the theory, which depending on the properties of the initial density matrix can be interpreted as a decay of a classically forbidden quantum state. Published by the American Physical Society 2024

Influence of Organic Spacer Cation on Dark Excitons in 2D Perovskites

AbstractThe organic spacer cation plays a crucial role in determining the exciton fine structure in 2D perovskites. Here, magneto‐optical spectroscopy is used to gain insight into the influence of the organic spacer on dark excitons in Ruddlesden–Popper (RP) perovskites. Using modest magnetic field strengths (&lt;1.5 T), the optically forbidden dark exciton state can be identified and its emission properties significantly modulated via application of in‐plane magnetic fields, up to temperatures of 15 K. At low temperatures, an increase in collected photoluminescence efficiency of &gt;30% is demonstrated, signifying the critical role of the dark exciton state for light‐emitting applications of 2D perovskites. The exciton fine structure and the degree of magnetic‐field‐induced mixing are significantly impacted by the choice of organic spacer cation, with 4–methoxyphenylethylammonium (MeO‐PEA) showing the largest effect due to larger bright–dark exciton splitting. This study distinguishes between interior (bulk) and surface dark‐exciton emission, showing that bright–dark exciton splitting differs between the interior and surface. The results emphasize the significance of the organic spacer cation in controlling the exciton fine structure in 2D perovskites and have important implications for the development of optoelectronic technology based on 2D perovskites.

The reaction rate of radiative n8Li capture in the range from 0.01 to 10 T9

Within the modified potential cluster model (MPCM) with forbidden states, the total cross sections are calculated for capture in the ground and first excited states of the9Li nucleus in then8Li channel in the energy range from 10−5 eV to 5 MeV based onЕ1 andM1 transitions. The experimentally proved resonance atEc.m.= 0.232 MeV in the4P5/2wave andab initio-predicted4P3/2resonance at 1.32 MeV [Phys. Rev. C 103, 035801 (2021)] are considered. The strong impact of the asymptotic constant and channel spectroscopic factors on the total capture cross sections are responsible for the variation in the absolute values within factor two. As a consequence, the thermal cross sections areσtherm=24–46.8 mb. The evaluation ofσthermbased on the extrapolation ofab initiocross sections yields ∼85 mb. The reaction rate is calculated in the temperature range from 0.01 to 10T9. The reported reaction rates are compared at the benchmark point 1T9. The comparison of two datasets [Phys. Rev. C 103, 035801 (2021) and Phys. Rev. C 105, 064608 (2022)] on reaction rates recently calculated in microscopic models in extended temperature intervals shows the essential quantitative and qualitative differences. The comparative joint analysis of the reaction rates of radiative neutron capture on the lithium isotopes6,7,8Li is suggested for the choice of an optimal interval for the asymptotic constants.

Radiative 9Be(n,γ0+1+2+3+4+5)10Be reaction rate in the potential cluster model* *Supported by the Ministry of Science and Higher Education of the Republic of Kazakhstan (AP09259021)

Within the framework of the modified potential cluster model with forbidden states, the total cross-sections of radiative n 9Be capture to the ground and five low-lying excited states are calculated at energies from 10−2 eV up to 5 MeV. The thermal cross-section mb is in good agreement with experimental data. We considered five resonances at the excitation energies E x from 7.371 MeV up to 10.570 MeV corresponding to the following states with (E x , MeV): (7.371), (7.542), (9.4), (9.56), and (10.570). The partial and total 9Be(n,γ 0+1+2+3+4+5)10Be reaction rates are calculated at temperatures from 0.001 to 10 T 9. Contrary to the available data, we propose that the rise in the reaction rate near factor five at T 9 \\gt 1 is mainly due to the first (E R = 0.559 MeV) resonance. We foresee this contrast as arising from different model approaches.

Robust Stealthy Attacks Based on Uncertain Costs and Labeled Finite Automata With Inputs

This paper deals with the vulnerability analysis of cyber-physical systems subject to malicious actions. For this purpose, the considered system is assumed to be abstracted as a discrete event system. Labeled finite automata with inputs are used to model the system's behavior along with the information that circulates in both the input and output channels. In particular, we study here stealthy, i.e., undetectable, cyber-attacks that aim to drive the system from a given normal state to a set of forbidden states. We assume that the attacker has limited resources, i.e., a credit, to insert and delete control and sensors events. The proposed analysis evaluates the costs of such attacks on the controlled system depending on its structure, the cost of the malicious actions and possible uncertainties that may affect those costs. It provides systematic methods that aim to compute attacks of minimal cost and robust attacks that are weakly impacted by uncertainties. A case study representing a manufacturing plant is considered to illustrate the results.

Measuring autoionization decay lifetimes of optically forbidden inner valence excited states in neon atoms with attosecond noncollinear four-wave-mixing spectroscopy

Attosecond noncollinear four wave mixing spectroscopy with one attosecond extreme ultraviolet (XUV) pulse and two few-cycle near-infrared (NIR) pulses was used to measure the autoionization decay lifetimes of inner valence electronic excitations in neon atoms. After a 43-48 eV XUV photon excites a 2s electron into the 2s2p6[np] Rydberg series, broadband NIR pulses couple the 2s2p6[3p] XUV-bright state to neighboring 2s2p6[3s] and 2s2p6[3d] XUV-dark states. Controllable delays of one or both NIR pulses with respect to the attosecond XUV pulse reveal the temporal evolution of either the dark or bright states, respectively. Experimental lifetimes for the 3s, 3p, and 3d states are measured to be 7 +/- 2 fs, 48 +/- 8 fs, and 427 +/- 40 fs, respectively, with 95% confidence. Accompanying calculations with two independent ab initio theoretical methods, NewStock and ASTRA, verify the findings. The results support the expected trend that the autoionization lifetime should be longer for states that have a smaller penetration in the radial region of the 2s core hole, which in this case is for the higher angular momentum Rydberg orbitals. The underlying theory thus links the lifetime results to electron correlation and provides an assessment of the direct and exchange terms in the autoionization process.

Design of Controllers Considering the Number of Control Places for Forbidden State Problem of Petri Nets

Design of Controllers Considering the Number of Control Places for Forbidden State Problem of Petri Nets

Resonance ionization spectrum of autoionization states of lutetium atom

&lt;sup&gt;177&lt;/sup&gt;Lu is an important medical isotope used in imaging-guided radiotherapy, and it can be produced by irradiating &lt;sup&gt;176&lt;/sup&gt;Lu or &lt;sup&gt;176&lt;/sup&gt;Yb with high abundance. With an increasing demand for medical isotopes, it is very essential to improve the supply capacity for &lt;sup&gt;177&lt;/sup&gt;Lu. The multi-step multi-color photoionization method is an effective method to obtain isotopes, and the information of odd-parity autoionization levels is essential. Laser resonance ionization spectroscopy is one of a few spectroscopic experimental methods that can study autoionization levels. An experimental system is developed for the frontier spectroscopic research, and it consists of custom-made tunable lasers and a high-resolution time of flight mass spectrometer. The lifetime of the excited state 35274.5 cm&lt;sup&gt;–1&lt;/sup&gt; is measured to be (31.6 ± 1.7) ns by the delayed photoionization method for the first time. A three-step three-color photoionization process is used to detect the autoionization levels, with a delay of 30 ns between &lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;2&lt;/sub&gt; – &lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;1&lt;/sub&gt; and &lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;3&lt;/sub&gt; – &lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;2&lt;/sub&gt; respectively, in order to avoid any unexpected transitions. Forty-seven odd-parity autoionization levels are obtained, of which 33 levels are discovered for the first time, and the &lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;2&lt;/sub&gt; and &lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;1&lt;/sub&gt; are blocked to exclude possible interference peaks, such as the &lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;1&lt;/sub&gt;+&lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;3&lt;/sub&gt;+&lt;i&gt;λ&lt;/i&gt;&lt;sub&gt;3&lt;/sub&gt; transition. Several autoionization levels show asymmetrical peak shapes, and the Fano fitting is carried out for all the levels to determine the widths and relative transition strengths of the autoionizing transitions. This study provides critical data for the high-efficient photoionization of lutetium atoms in the visible range. The angular momenta of 21 odd-parity autoionization levels in an energy range of 50650–51650 cm&lt;sup&gt;–1&lt;/sup&gt; are identified for the first time, which provides a reference for determining the forbidden state of electric dipole transitions from other excited states and ascertaining the electronic configuration.

Spatial Structure of the $${}^{{12}}$$C Nucleus in a 3$$\alpha$$ Model with Deep Potentials Containing Forbidden States

The spatial structure of the lowest 0 $${}_{1}^{+}$$ , 0 $${}_{2}^{+}$$ , 2 $${}_{1}^{+}$$ and 2 $${}_{2}^{+}$$ states of the $${}^{12}$$ C nucleus is studied within the 3 $$\alpha$$ model with the Buck, Friedrich and Wheatley $$\alpha\alpha$$ potential with Pauli forbidden states in the $$S$$ and $$D$$ waves. The Pauli forbidden states in the three-body system are treated by the exact orthogonalization method. The largest contributions to the ground and excited 2 $${}_{1}^{+}$$ bound states energies come from the partial waves $$(\lambda,\ell)=(2,2)$$ and $$(\lambda,\ell)=(4,4)$$ . In contrast to the bound states, for the Hoyle resonance 0 $${}_{2}^{+}$$ and its analog state 2 $${}_{2}^{+}$$ , dominant contributions come from the $$(\lambda,\ell)=(0,0)$$ and $$(\lambda,\ell)=(2,2)$$ configurations, respectively. The estimated probability density functions for the $${}^{12}$$ C(0 $${}_{1}^{+}$$ ) ground and 2 $${}_{1}^{+}$$ excited bound states show mostly a triangular structure, where the $$\alpha$$ particles move at a distance of about 2.5 fm from each other. However, the spatial structure of the Hoyle resonance and its analog state have a strongly different structure, like $${}^{8}\textrm{Be}+\alpha$$ . In the Hoyle state the last $$\alpha$$ particle moves far from the doublet at the distance between $$R=3.0$$ fm and $$R=5.0$$ fm. In the Hoyle analog 2 $${}_{2}^{+}$$ state the two alpha particles move at a distance of about 15 fm, but the last $$\alpha$$ particle can move far from the doublet at the distanse up to $$R=30.0$$ fm.

Theoretical Investigation of the Electronic Spectra of Cadmium Chalcogenide 2D Nanoplatelets.

Although colloidal cadmium chalcogenide 2D nanoplatelets (NPLs) have recently demonstrated strongly enhanced one- and two-photon absorption (OPA, TPA) spectra, an understanding of the effects of quantum confinement in the lateral and vertical (thickness) dimensions is mostly lacking. In this work, we investigate theoretically CdS and CdSe NPLs passivated with formate and acetate ligands with thicknesses of two and three monolayers (MLs) and different lateral dimensions. Initial structures for CdS nanoplatelets were obtained using our recently developed deep neural network potential, and the low-energy geometries were subsequently optimized using density functional theory (DFT). Linear- and nonlinear-response calculations using time-dependent DFT (TDDFT) and the simplified Tamm-Dancoff approximation (sTDA) demonstrated good agreement between measured spectra and calculated TDDFT and sTDA spectra for 2 and 3 ML NPLs. The OPA red-shifts from 2 to 3 ML NPLs can be attributed to the electron delocalization in the lateral and vertical directions. TPA responses for CdS and CdSe NPLs were found to be dominated by weakly absorbing and forbidden OPA states.

Reaction rate of radiative p12N capture

The S-factor of radiative p12N capture at energies from 20 keV to 5 MeV was considered within the modified potential cluster model with forbidden states, considering the first resonance at Ex = 2.69(5) MeV. It was shown that one can obtain the astrophysical S-factor based on potentials consistent with the bound state energies and asymptotic constant values. According to the theoretical total cross sections, the calculation of the p12N capture reaction rate is made at temperatures from 0.001 to 10 T9. The calculated results for the reaction rate are approximated by analytical expression, which simplifies their use in applied research.

Reaction rate of radiative n6Li capture in the temperature range from 0.01 to 10 T9

We consider the rate of radiative n6Li capture reaction in the temperature range from 0.01 to 10 T9 within the framework of the modified potential cluster model with forbidden states. The total cross sections are calculated for capture to the ground, and the first excited states of the 7Li nucleus in the n6Li channel in the energy range from 10 meV to 5 MeV. Analytical expressions approximate the total cross-section at low energies and the reaction rate over the entire considered temperature range.

Online dynamic rumour propagation model considering punishment mechanism and individual personality characteristics

Abstract In the Internet era, rumours will spread rapidly in the network and hinder the development of all aspects of society. To create a harmonious network environment, it is essential to take punitive measures against malicious rumour mongers on social platforms. Take the measure of forbidden as an example. The forbidden one may stop spreading rumours because of being punished, or he may become a disseminator again because of paranoia. Other people who know rumours may become alert and stop propagating rumours or temporarily forget rumours. And therefore, the forbidden state is added to describe the above phenomenon, and the SIFR (Ignorant–Disseminator–Forbidden–Restorer) model is proposed. Taking the vigilance and paranoia derived from punishment measures into account, the connection edges from the forbidden to the disseminator and from the disseminator to the restorer are increased in this model. And then, the stability of SIFR model is proved by using the basic regeneration number and Routh–Hurwitz stability theorem. The simulation results demonstrate that individual paranoia may do harm to the control of rumour dissemination. While the punishment mechanism, individual forgetting mechanism and vigilance can effectively curb the spread of rumours.

Li6(p,γ)Be7reaction rate in the light of the new data of the Laboratory for Underground Nuclear Astrophysics

We present new calculations of the astrophysical $S-$factor and reaction rate for the $^{6}$Li$(p,\gamma )^{7}$Be reaction at energies of 10 keV to 5 MeV in the framework of a modified potential cluster model with forbidden states, including low lying resonances. The astrophysical $S(E)-$factor is compared with the available experimental data and calculations done within different models. The results for the $S-$factor are in good agreement with the data set (for $E<0.3$ MeV) and calculations (for $E<0.6$ MeV) of LUNA collaboration (Phys. Rev. C 102$,$ 052802, 2020). The recommended extrapolated zero value $S(0)$ turned out to be 101 eV $\cdot $ b. Using the theoretical total cross-sections$,$ the $^{6}$Li$(p,\gamma)^{7} $Be capture reaction rate is calculated at temperatures ranging from 0.01 to 10 $T_{9}$ and compared with NACRE and NACRE II. Analytical expressions for the $S-$factor and reaction rate are given, and the effect of low-lying resonances on the reaction rate is estimated. We suggest to update the NACRE and NACRE II databases in light of the new LUNA data and present calculations.

Peculiarity of the $${}^{{12}}$$C(0$${{}^{+}}$$) and $${}^{{12}}$$C(2$${{}^{+}}$$) Energy Spectrum in a 3$$\alpha$$ Model

Lowest energy spectrum of the $${}^{12}$$ C nucleus is analyzed in the 3 $$\alpha$$ -cluster model with a deep $$\alpha\alpha$$ potential of Buck, Friedrich and Wheatley with Pauli forbidden states in the $$S$$ and $$D$$ waves. The direct orthogonalization method is applied for the elimination of the 3 $$\alpha$$ Pauli forbidden states. The effects of possible first order quantum phase transition are shown in the lowest $${}^{12}$$ C( $$0_{1}^{+}$$ ) and $${}^{12}$$ C( $$2_{1}^{+}$$ ) states from weakly bound phase to a deep phase. The ground and lowest 2 $${}^{+}$$ states of the $${}^{12}$$ C nucleus in the deep phase are created by the critical eigen states of the Pauli projector for the 0 $${}^{+}$$ and 2 $${}^{+}$$ three-alpha functional spaces, respectively.

Plasmon-induced near-infrared fluorescence enhancement of single-walled carbon nanotubes

Single-walled carbon nanotubes (SWCNTs) emit near-infrared (NIR) fluorescence that is ideal for optical sensing. However, the low quantum yields diminish the sensor’s signal-to-noise ratio and limits the penetration depths for in vivo measurements. In this study, we perform a systematic investigation of the plasmonic effects of Ag and Au nanoparticles of various geometries to tune and even enhance the fluorescence intensity of single-stranded DNA-wrapped SWCNTs (ssDNA-SWCNTs). We observe a chirality-dependent NIR fluorescence enhancement that varies with both nanoparticle shape and material, with Au nanorods increasing (7, 5) and (7, 6) chirality emissions by 80% and 60% and Ag nanotriangles increasing (7, 5) and (6, 5) emissions by 200% and 240%, respectively. The chirality-dependent enhancement was modeled using finite element modeling (FEM), which confirms contributions not only from a plasmon-induced localized increase in electron density but also from the radiative recombination of dark exciton states from the resulting electromagnetic field. Finally, we demonstrate the application of these nanoparticles in enhancing the single-molecule fluorescence of individual SWCNTs imaged in a custom-built confocal setup. The plasmonically coupled sensors show four orders of magnitude greater sensitivity towards ferricyanide, a model analyte, compared to the non-coupled sensors. Plasmonic nanoparticles thus provide a tunable means of modulating SWCNT fluorescence to study fundamental transitions of otherwise forbidden states and to improve the optical sensing performance.

Anomalous emission behavior of excitons at low temperature in monolayer WS2

We report on the anomalous emission behavior of excitons (X) in monolayer WS2 using temperature dependent photoluminescence spectroscopy. In general, PL emission from excitons enhances with decreasing temperature due to suppression of phonon mediated non-radiative transitions. Here, we observe that excitonic PL is temperature independent, although with decreasing temperature, the emission intensity for trion (X −) and biexciton or defect-bound excitons (XX/L 1) increases up to 123 K and then decreases. Analysis of experimental data with a model derived from the Boltzmann distribution and Saha equation reveal conversion of excitons into trions, biexcitons or defect-bound excitons and an increase of spin forbidden dark state with reduction in temperature. These findings could provide better strategies for designing future quantum devices.

BODIPY nanoparticles functionalized with lactose for cancer-targeted and fluorescence imaging-guided photodynamic therapy

A series of four lactose-modified BODIPY photosensitizers (PSs) with different substituents (-I, -H, -OCH3, and -NO2) in the para-phenyl moiety attached to the meso-position of the BODIPY core were synthesized; the photophysical properties and photodynamic anticancer activities of these sensitizers were investigated, focusing on the electronic properties of the different substituent groups. Compared to parent BODIPY H, iodine substitution (BODIPY I) enhanced the intersystem crossing (ISC) to produce singlet oxygen (1O2) due to the heavy atom effect, and maintained a high fluorescence quantum yield (ΦF) of 0.45. Substitution with the electron-donating methoxy group (BODIPY OMe) results in a significant perturbation of occupied frontier molecular orbitals and consequently achieves higher 1O2 generation capability with a high ΦF of 0.49, while substitution with the electron-withdrawing nitro group (BODIPY NO2) led a perturbation of unoccupied frontier molecular orbitals and induces a forbidden dark S1 state, which is negative for both fluorescence and 1O2 generation efficiencies. The BODIPY PSs formed water-soluble nanoparticles (NPs) functionalized with lactose as liver cancer-targeting ligands. BODIPY I and OMe NPs showed good fluorescence imaging and PDT activity against various tumor cells (HeLa and Huh-7 cells). Collectively, the BODIPY NPs demonstrated high 1O2 generation capability and ΦF may create a new opportunity to develop useful imaging-guided PDT agents for tumor cells.