Search

Advance automation digitization and interconnectivity are driving rapid evolution in the manufacturing industry As a result smart manufacturing has become increasingly popular driven by the integration of deep reinforcement learning DRL and digital twins in agent training DRL has proven to be particularly effective in smart manufacturing allowing agents to respond dynamically to an ever changing environment with a wide range of manufacturing components which leads to a slight variation in the objectives This study proposes an efficient DRL approach to smart manufacturing tasks by breaking them into three simpler tasks reach push and pick and place The Truncated Quantile Critics TQC algorithm is employed as the learning algorithm for the agent which is trained using Hindsight Experience Replay HER to formulate virtual goals in a sparserewarded environment Our experiments on these environments demonstrate that the proposed method of TQC HER achieves the best results on all three of the smart manufacturing tasks

Nitrogen doping is an important method to modulate electronic structure of two-dimensional carbon materials. The properties of the doped systems are heavily dependent on the local structure of nitrogen dopants involved, which are often determined by experimental X-ray photoelectron spectra (XPS) and near-edge X-ray absorption fine-structure (NEXAFS) at the nitrogen K-edge. In the present work, the N1s XPS and NEXAFS spectra of nitrogen-doped graphdiynes have been accurately calculated at the density functional theory level. Five representative nitrogen-dopants in graphdiynes, namely [pyridinic, amino, graphitic, and two sp-hybridized N (sp-N-1 and sp-N-2) local structures], are fully examined, from which all experimental features could be correctly assigned. The calculated results can be used to determine the ratio of different nitrogen dopants in graphdiyne at different elevated temperatures reported in previous experiments. Our findings provide the basic references for structure determination of nitrogen doped graphdiyne and new understanding of the underlying structure-property relationships., QC 20190712

The Precision Medicine Initiative is a multicenter effort aiming at formulating personalized treatments leveraging on individual patient data (clinical, genome sequence and functional genomic data) together with the information in large knowledge bases (KBs) that integrate genome annotation, disease association studies, electronic health records and other data types. The biomedical literature provides a rich foundation for populating these KBs, reporting genetic and molecular interactions that provide the scaffold for the cellular regulatory systems and detailing the influence of genetic variants in these interactions. The goal of BioCreative VI Precision Medicine Track was to extract this particular type of information and was organized in two tasks: (i) document triage task, focused on identifying scientific literature containing experimentally verified protein–protein interactions (PPIs) affected by genetic mutations and (ii) relation extraction task, focused on extracting the affected interactions (protein pairs). To assist system developers and task participants, a large-scale corpus of PubMed documents was manually annotated for this task. Ten teams worldwide contributed 22 distinct text-mining models for the document triage task, and six teams worldwide contributed 14 different text-mining systems for the relation extraction task. When comparing the text-mining system predictions with human annotations, for the triage task, the best F-score was 69.06%, the best precision was 62.89%, the best recall was 98.0% and the best average precision was 72.5%. For the relation extraction task, when taking homologous genes into account, the best F-score was 37.73%, the best precision was 46.5% and the best recall was 54.1%. Submitted systems explored a wide range of methods, from traditional rule-based, statistical and machine learning systems to state-of-the-art deep learning methods. Given the level of participation and the individual team results we find the precision

Six stable C84 isomers satisfying isolated pentagon rule (IPR) have been theoretically identified by infrared (IR), X-ray photoelectron (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectra. The XPS and NEXAFS spectra at the K-edge for all nonequivalent carbon atoms were simulated by the density functional theory method. NEXAFS spectra show stronger dependence than IR and XPS spectra on the six C84 isomers, which can be properly used for isomer identification. Furthermore, spectral components of total spectra for carbon atoms in different local environment have been explored., Export Date: 9 May 2018; Article; CODEN: JPCAF; Correspondence Address: Song, X.-N.; Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, School of Physics and Electronics, Shandong Normal UniversityChina; email: xiuneng@sdnu.edu.cn; Funding details: Shandong Province; Funding details: MOE, Ministry of Education; Funding details: CFSR, Canon Foundation for Scientific Research; Funding details: 11374195, NSFC, National Natural Science Foundation of China; Funding details: 21303096, NSFC, National Natural Science Foundation of China; Funding details: 11404193, NSFC, National Natural Science Foundation of China; Funding text: This work is supported by the National Natural Science Foundation of China (Grant Nos. 11404193, 21303096, and 11374195) and the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry. Thanks to the support of the Taishan scholar project of Shandong Province. QC 20180528

Previous studies measured gravel bed surfaces by terrestrial laser scanning (TLS) and close-range photogrammetry suggested the presence of at least two different scales of spatial variation in gravel bed surfaces. This study investigated the spatial variation of airborne laser scanning (ALS) point clouds acquired in gravel bed. Due to the large footprint of ALS systems, a smoother surface is expected, but there exists some uncertainty over the precise scale of ALS measurement (hereafter referred to as the spatial support). As a result, we applied the regularization method, which is a variogram upscaling approach, to investigate the true support of ALS data. The regularization results suggested that the gravel bed surface described by the ALS is much smoother than expected in terms of the ALS reported measurement scale. Moreover, we applied the factorial kriging (FK) method, which allows mapping of different scales of variation present in the data separately (different from ordinary kriging which produces a single map), to obtain the river bed topography at each scale of spatial variation. We found that the short-range and long-range FK maps of the TLS-derived DSMs were able to highlight the edges of gravels and clusters of gravels, respectively. The long-range FK maps of the ALS data shows a pattern of gravel-bed clusters and aggregations of gravels. However, the short-range FK maps of the ALS data produced noisy maps, due to the smoothing effect. This analysis, thus, shows clearly that ALS data may be insufficient for geomorphological and hydraulic engineering applications that require the resolution of individual gravels. © 2018 G.-H. Huang et al. published by De Gruyte.

Previous studies measured gravel bed surfaces by terrestrial laser scanning (TLS) and close-range photogrammetry suggested the presence of at least two different scales of spatial variation in gravel bed surfaces. This study investigated the spatial variation of airborne laser scanning (ALS) point clouds acquired in gravel bed. Due to the large footprint of ALS systems, a smoother surface is expected, but there exists some uncertainty over the precise scale of ALS measurement (hereafter referred to as the spatial support). As a result, we applied the regularization method, which is a variogram upscaling approach, to investigate the true support of ALS data. The regularization results suggested that the gravel bed surface described by the ALS is much smoother than expected in terms of the ALS reported measurement scale. Moreover, we applied the factorial kriging (FK) method, which allows mapping of different scales of variation present in the data separately (different from ordinary kriging which produces a single map), to obtain the river bed topography at each scale of spatial variation. We found that the short-range and long-range FK maps of the TLS-derived DSMs were able to highlight the edges of gravels and clusters of gravels, respectively. The long-range FK maps of the ALS data shows a pattern of gravel-bed clusters and aggregations of gravels. However, the short-range FK maps of the ALS data produced noisy maps, due to the smoothing effect. This analysis, thus, shows clearly that ALS data may be insufficient for geomorphological and hydraulic engineering applications that require the resolution of individual gravels. © 2018 G.-H. Huang et al. published by De Gruyte.

The effects of contact structures and isomers on the current-voltage characteristics of molecular bipyridine junctions have been investigated by means of a generalized quantum chemical approach based on the elastic scattering Green's function method. For the four isomers 4,4'-bipyridine, 2,2'-bipyridine, 2,4'-bipyridine, and 2,6'-bipyridine under investigation, the 2,4'- bipyridine junction is found to be the poorest conductor owing to its nonsymmetrical arrangement. Numerical simulations of the 4,4'-bipyridine junction show that the contact structures between molecule and metallic electrodes have a noticeable effect on the electron transport characteristics of molecular junctions. The shortening of the distance between two metallic electrodes results in a stronger coupling and lower potential barrier between them, leading to larger conductance. The external electric fields cause the charge redistribution within molecule and lead to the presence of resistivity dipoles at the molecule-metal interface, and the bias voltages are mainly dropped there. The nonlinear charge transport effect on the current and conductance of 4,4'-bipyridine molecular junctions at the lower-bias region is presented. The experimental measurement has been reproduced by the theoretical calculations for a well-defined structure., QC 20100525

By applying the elastic scattering Green's function theory in combination with the hybrid density function theory, the electronic transport properties of molecular junctions constructed by the six-membered heterocyclic molecules, pyridazine-2, 5-dithiol, pyrazine-2, 5-dithiol, and pyrimidine-2, 5-dithiol, have been studied. For the heterocyclic molecule pyridine, the influence of the terminal atoms on the current-voltage characteristics has also been obtained. We have accurately determined the coupling constant between the molecule and electrodes by using the frontier molecular orbital theory and the perturbation method. The numerical results show that pyridazine-2,5-dithiol has higher current and conductance, while the conductance of pyrimidine-2, 5-dithiol is very small when the bias voltage is lower than 4V. The conductivity of the molecule pyridine with selenium atom as the terminal atom is higher than that with oxygen atom or sulfur atom., QC 20100525

Influences of electrode distances on geometric structure of molecule and on electronic transport properties of molecular junctions have been investigated by means of a generalized quantum chemical approach based on the elastic scattering Green's function method. Numerical results show that, for organic molecule 4,4'-bipyridine, the geometric structure of the molecule especially the dihedral angle between the two pyridine rings is sensitive to the distances between the two electrodes. The currents of the molecular junction are taken nonlinearly increase with the increase of the bias. Shortening the distance of the metallic electrodes will result in stronger coupling and larger conductance., QC 20141127

The influence of external voltage on the charge transport properties of benzene-1,4-dithiolate molecular junction has been investigated. Variations of the geometric and electronic structures for the molecule caused by the applied voltage are calculated at ab initio level. Based on the numerical results, we find that the energy shift and expansion coefficients in the end-site of the molecule for the frontier molecular orbitals show nearly linear dependence on voltage in the interested voltage interval. The charge transport properties of the molecular junction are then studied by employing the elastic scattering Green's function method. It is shown that the voltage has an obvious effect on the I - V characteristic of the molecular junction, particularly the shape of the conductance curves. The I - V curves are consistent with the experimental measurement quite well., QC 20100525

We have investigated the resonant propagation of femtosecond laser pulse in 4-trans-[p-(N, N-Di-n-butylamino)-p-stilbenyl vinyl] pyridine medium with permanent dipole moments. The electronic structures and parameters for the compound have been calculated by using density functional theory. In the optical regime, there is one charge-transfer state, and the molecule can thus be simplified as a two-level system. Both the one- and two-photon transitions occur between the ground and charge-transfer states. The numerical results show that the permanent dipole moments have an obvious effect on the propagation of the ultrashort pulse laser. The ideal self-induced transparency disappears for 2 pi pulse, and second harmonic spectral components occur significantly due to the two-photon absorption process. For the 6 pi pulse, continuum frequency generation is produced and a shorter duration pulse in time domain with 465 as is obtained., QC 20100525

The nonlinear optical properties of two newly synthesized molecules 9-Ethyl-3-{2-[4-(2-Pyridin-4-yl-vinyl)-phenyl]vinyl}-9H-carbazole (EPVPC) and 9-Octadecyl-3-{2-[4-(2-Pyridin-4-yl-vinyl)-phenyl]-vinyl}-9H-carbazole (OPVPC) have been studied with hybrid density functional theory (DFT/B3LYP). The generalized few-state model is employed to calculate the two-photon absorption cross sections of the compounds. The theoretical results are in good agreement with the available experimental measurements. It is found that the maximal two-photon absorption (TPA) cross sections of the compounds can be well described by a three-state model. The numerical simulation shows that both compounds have large two-photon absorption (TPA) cross sections and, furthermore, OPVPC displays a little stronger TPA activity than EPVPC in a lower frequency region., QC 20100525

The one-photon and two-photon absorption properties of a series of 1, 4-dimethoxy-2, 5-divinyl-benzene derivatives are investigated by use of the analytic response theory at HF level. The one-photon and two-photon fluorescence spectra of E, E-2-5Bis[4'-(N, N-di-n-butylamino) styryl]-1 4-dimenthoxybenzene are measured. The numerical results show that these molecules have strong two-photon absorption cross sections. In the visible light region, the maximal one-photon absorption strengths of the molecules occur in the first excited state. Furthermore, the maximal two-photon absorption cross sections of the D-pi-A typed molecules still appear in the first state, but for D-pi-D typed molecules the second excited state has the maximal two-photon absorption cross-section. The optical properties of the molecules are closely related to the electric property of the donor and acceptor. The symmetrically substituted molecules can not be determined to have a larger two-photon absorption cross section than the asymmetrically substituted molecules for such a kind of pi-center. The charge-transfer process for the charge-transfer states is displayed, and then the mechanism of photopolymerization is discussed qualitatively., QC 20100525

The dynamic behaviour of ultrashort (femtosecond) laser pulses in a molecular medium is studied by solving the full Maxwell-Bloch equations beyond the limits of the slowly varying envelope approximation and the rotating-wave approximation under the resonant and the non-resonant conditions. A one-dimensional asymmetric charge-transfer molecule, para-nitroaniline, is used as a model molecule whose electronic properties are calculated with the time-dependent hybrid density functional theory. Under the one-photon resonant condition, 4 pi pulse is separated into two sub-pulses. The weight of the second-harmonic component mainly contributed by the two-photon excitation becomes stronger with longer propagation time. Under the two-photon resonant condition, the separation of 4 pi pulse is not induced and many higher-order spectral components beyond the second-harmonic generation occur. Interestingly, when the pulse propagates for long enough, the carrier modification becomes so significant that a continuous spectrum is generated. The Fourier transform of the high-harmonic spectrum demonstrates that an even shorter laser pulse can be produced in both resonant and non-resonant propagations. The effects of permanent dipole moments on the pulse evolution are discussed., QC 20100525

The electrodes can be constructed by different dimensionality of electronic systems in energy representation when the current through the molecular junction is measured. Basing on the elastic scattering Green function theory, we have developed the theoretical methods for studying the electronic transport properties of molecular junctions and paid attention to the influence of the dimensionality of electrodes. The alpha, alpha'-xylyl dithiol molecule is taken as an example and its current-voltage characteristics have been investigated for electrodes with different-dimension electronic systems. The numerical results show that dimensionality of metal contacts has strong effect on the current-voltage characteristics of molecular junction, in particular the shape of the conductance curves., QC 20100525

The elastic scattering Green function method has been developed to describe the IN characteristics of molecular wires. The molecular electronic structure and the interaction between the molecule and the gold surface are two key factors for the charge transport properties of molecular wires in the formulas. An ab initio calculation at the hybrid density functional theory level is carried out to obtain the electronic structure of 4-4'-dimercaptodibenzene molecule. The frontier orbit theory and the perturbation theory are employed to determine the constant of the interaction energy between molecule and surface quantitatively. The numerical results show that the bonding between the sulfur atom and the gold atoms corresponds mainly to the covalent bond. Some molecular orbits are extended over molecule and gold cluster that certainly give channels for the charge transport, other molecular orbits are localized and the charge transport can take place by tunnel mechanism. At zero bias region, there exists a current gap. With the increasing bias, the conductance of the wire takes a shape of plateaus., QC 20100525

Time-dependent hybrid density functional theory in combination with polarized continuum model has been applied to study the solvent effects on the geometrical and electronic structures, as well as one- and two-photon absorption processes, of a newly synthesized asymmetrical charge-transfer (CT) two-photon absorption (TPA) organic molecule. The TPA cross section calculated from a generalized two-state model and solvatochromic shift of the CT state are found to be solvent dependent, for which a nonmonotonic behavior with respect to the polarity of the solvents has been observed. The calculated properties are in good agreement with the experimental data available. The character of the CT state is visualized by plotting its charge density difference from ground state, in which an excess of electron density on the donor side of the molecule is found. This implies that the excited molecule is ready to donate its electron to the surroundings. The energetic aspect of the electron donation is discussed by examining the solvent dependence of the molecular ground state oxidation potential. The importance of the electron correlation for describing the two-photon absorption is also demonstrated., QC 20100525

Resonant two-photon absorption (TPA) cross sections of a series of diphenylaminofluorene-based chromophores with various electron acceptors are predicted using the random phase approximation and using hybrid density functional theory implemented for a two-state model. A comparison of the two methods indicates that the two-state model is adequate for describing the TPA cross sections of all asymmetrical charge-transfer systems under investigation. It is demonstrated that the inclusion of electron correlation can drastically increase the absolute values of the TPA cross sections, but that it has negligible effects on the relative order of the TPA activity of the molecules., QC 20100525

The electronic transport properties of molecular junctions constructed by the five-membered heteraromatic molecules -thiophene-1,4-dithiol, pyrrole-1,4-dithiol and furan-1,4-dithiol-in contact with gold electrodes have been calculated by applying the elastic scattering Green's function theory approach in combination with the hybrid density-functional theory without using any fitting parameters. It shows that the molecule with thiophene has similar conductivity as that with benzene-1,4-dithiol. The ordering of the five-membered heteraromatic molecules in terms of conductivity is thiophene > pyrrole > furan., QC 20100525

Formalisms for current-voltage (I-V) characteristics of a single molecular junction with electrodes possessing one-, two-, and three-dimensional energy distributions are derived and compared in the framework of elastic scattering theory. Model calculations on a device constituted of 1,4 benzene-dithiolate molecule chemically bonded to two gold electrodes are carried out using hybrid density functional theory. It is shown that the dimensionality of metal contacts has a strong effect on the I-V characteristics of the molecular junction, in particular the shape of the conductance curves. Good agreement with experimental I-V curves has been found for the case of the three-dimensional electron system., QC 20100525

We have shown an accurate theoretical description for electronic transport properties of molecular junctions. By applying the elastic scattering Green's function theory approach in combination with the frontier molecular orbital theory for describing the surface-molecule coupling and the hybrid density-functional theory for geometrical and electronic structures calculations, reliable predictions are obtained about the chemical and physical modifications on the current-voltage characteristics of molecular junctions, due to molecular geometrical relaxation, the choice of terminal atoms, the effect of donor/acceptor substitutions, as well as their thermal rotations., QC 20100525

We have theoretically examined a series of organic molecules that exhibit large two-photon absorption cross sections in the visible region and that have been synthesized in different laboratories. One- and two-photon absorption cross sections of the four lowest excited states of each molecule have been calculated at the same theoretical level using ab initio response theory. It is found that the molecular length and the one-photon absorption intensity are quite strongly correlated factors, but that a corresponding correlation for the two-photon absorption is much weaker or is missing. In contrast, a most crucial role for large two-photon absorption is played by the pi center. For molecules with a given pi center a symmetrical structure with strong donor groups can result in a maximum two-photon absorption cross section. Our theoretical findings are consistent with some recent experimental observations. The chromophore based on dithienothiophene as pi center attached with symmetrical N,N-diphenylamine donors is found to have the largest two-photon cross section in the visible region among all known one-dimensional two-photon organic materials that have been reported in the literature., QC 20100525

Intermolecular hydrogen-bonding in thick films of isonicotinic acid evaporated onto rutile TiO2(110) has been investigated with X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The rate of deposition is found to be a key factor in overcoming the kinetic barriers to extensive hydrogen-bond formation, which, when present, gives rise to large energy shifts between bulk and surface in both the N1s XPS and XAS. The origin of the surface core-level shift is attributed to the presence of non-hydrogen-bonded nitrogen atoms in the surface layer., QC 20100525

QCR 20170112