Algebraic-Connectivity-Based Multi-USV Distributed Formation Method via Adding a Reverse Edge

This paper concerns the formation problem in multi-USV cluster formation containment tracking tasks with a special topology. A topology reconstruction method was proposed that enables the followers’ formation to be dispersed while achieving the fastest convergence rate for the system. This topology structure is based on tree topology and DAG (directed acyclic graph) local structure stem as prototypes, using the principle of adding reverse edges on the stem to reduce algebraic connectivity. By adding a reverse edge to obtain a more dispersed formation, a method for selecting appropriate reverse edges was achieved. Through relevant theoretical quantitative and qualitative analysis, it was demonstrated that adding this reverse edge can enable the system to achieve the fastest convergence rate. Finally, through simulation experiments, it was verified that the selected reverse edge can optimize the formation of followers and achieve the fastest convergence rate

Evaluation on Soil Heavy Metal Pollution around Tailing Areas: A Case Study of Ag-Sb Deposit in Northeastern Guangdong

In October 2012, an evaluation using potential ecological hazard risk index was carried out on soil heavy metal pollution around Ag-Sb deposit tailing areas in northeastern Guangdong. Results indicate that (i) soil heavy metal pollution is mainly Cd-Ni compound pollution, including Cd content 0.31-2.66mg/kg (average content is 1.11 mg/kg), the situation of exceeding standard is serious (the rate of exceeding standard is 100%); the total potential ecological hazard risk index (RI) is between 50 and 300, and it is moderate pollution; (ii) in soil heavy metal content, only Ni and Cu are positively correlated. Since there is certain degree of Ni pollution in this deposit, the synergetic effect of Cu and Ni may deteriorate Ni pollution

Photofragment Translational Spectroscopy of CF3I at 238 nm: Vibrational Distribution of CF3 Fragments and Curve Crossing Probability

The photodissociation dynamics of CF3I at 238 nm was studied using our high resolution mini-TOF (time of flight) photofragment translational spectrometer. The results indicated the strongest signal comes from the I* channel of the (3)Q(0) parallel transition [i.e., CF3I(X)-> CF,I((3)Q(0))-> CF3(v)+I*, and the vibrational peaks of CF3 fragments were resolved. From the peak gap, both the overtone bands (v(1), v(2) = 0) and the combination bands(v(1), v(2) = 1) of CF3 fragments were partially resolved (v(1) = 701 cm(-1) , the symmetric stretch mode; v(2) = 1086 cm(-1), the umbrella mode) . At 238 nm, the ratio of the two band series was found with Sigma P(v(1), 1)/Sigma P(v(1), 0) = 0.48/0.52. The vibrational distribution of CF3 fragments were also measured. The branching fractions of the four pathways were 0.664 for X ->(3)Q(0)-> I*, 0.084 for X ->(3)Q(0)->(1)Q(1)-> I, 0.178 for) X ->(1)Q(1)-> I and 0.074 for X ->(1)Q(1)->(3)Q(0)-> I*. The experimental curve crossing probability for (3)Q(0)->(1)Q(1), was P-0 -> 1 = 0.112 and that for (1)Q(1)->(3)Q(0) was P-1 -> 0 = 0.294. The anisotropy parameter of I* channel was beta(I*) = 1.70, and that of I channel was beta(I) = -0.04

Study of the Ultrafast Processes of TPP, BuPc and NtBuPc

The ultrafast processes of tetra-phenyl-porphyrin(TPP), tetra-t-butyl-phthalocyanine(BuPc) and nitro-tri-t-butyl-phthalocyanine ( NrBuPc) have been investigated using the femtosecond time-resolved fluorescence depletion method. A sharp peak of the fluorescence depletion with delay time has been observed both for TPP and BuPc. An ultrafast two-photon absorption process has been proposed to explain the sharp peak observed. A long-lived fluorescence depletion has also been observed. It is causing by the stimulated-emission-pumping process produced by the intense probe laser pulses

Vibrational Spectra and Theoretical Calculations of cis- and trans-3Fluoro-N-methylaniline in the Neutral (S-0) and Cationic (D-0) Ground States

The mass-analyzed threshold ionization spectra of jet-cooled cis- and trans-3-fluoro-N-methylaniline (3FNMA) were recorded by ionizing via the vibrationless 00 and various vibrational levels of the S1 state. The adiabatic ionization energies of cis- and trans-3FNMA are determined to be 61 742 +/- 5 and 61 602 +/- 5 cm(-1), respectively. In the 0-1800 cm(-1) region, most of the observed vibrations in the D0 state result from the in-plane ring deformation and substituent-sensitive modes. For the high-frequency vibration region, the infrared-ultraviolet double-resonance and autoionization-detected infrared spectroscopies were applied to investigate the N-H and C-H stretching vibrations of bare 3FNMA in the S0 and D0 states. The C-H stretching vibrational information, which we failed to obtain for the bare 3FNMA cation, is complemented by recording the infrared-photodissociation spectra of its Ar cluster cation. It is revealed that a red-shifted frequency and an enhanced intensity are observed for the N-H stretch, while blue-shifted frequencies and greatly decreased intensities are found for both aromatic and the methyl C-H stretches. The blue shift of the C-H stretches is first explained by the balance of two factors, namely, the hyperconjugative interaction and the rehybridization effect. Analysis of the vibrational frequencies reveals a correlation between the relative stability of two rotamers in different electronic states and the relative rigidity of aromatic ring, indicating a mechanism of the long-range interactions through bond between the substituents. The density functional theory calculations can well reproduce the vibrational spectra in both S-0 and D-0 states. With the experimental and theoretical data, the substitution and conformation effects on the properties of 3FNMA in the S-0 and D-0 states, including the molecular structures, the reactive sites of electrophilic attack, and the vibrational behaviors, were discussed in detail

Ionization spectroscopies and theoretical calculations of cis and trans 3-fluoro-N-methylaniline-Ar-n(n=1,2) van der Waals clusters: Structures and binding energies

The ab initio and dispersion-corrected density functional theory (DFT) calculations of the van der Waals (vdW) clusters of cis and trans 3-fluoro-N-methylaniline-Ar-n (3FNMA-Ar-n) (n = 1,2) predict that, for cis and trans 3FNMA-Ar-1 clusters, the pi-bound geometry with the Ar atom sitting over the ring is the global minimum in both neutral and cationic states, while for cis and trans 3FNMA-Ar-2 clusters, the [pi vertical bar pi]-bound sandwich structure with two Ar ligands occupying nearly equivalent pi-bound positions above and"below the ring plane is the global minimum. The vibronic spectra of cis and trans 3FNMA-Ar-1 clusters in the S1 state were recorded by using one color and two-color resonant two-photon ionization (R2PI) techniques, the comparison of which-yields an estimate of the binding energy of cluster in the S-1 state. It is found that the linear correlation between the redshift of the S-1 <- S-0 electronic transition energy (E-1) of cluster and the Ei of the monomer also holds for the Ar clusters of hetero-di-substituted aromatics. By recording the photoionization efficiency (PIE) curves and mass-analyzed threshold ionization (MATT) dissociation spectra of cis and trans 3FNMA-Ar-1 clusters, the ionization energies (IE) and binding energies of clusters in the D-0 state are obtained. The MATI spectra of the cis and trans 3FNMA-Ar-1 cations exhibit significant progressions of the vdW bending mode (br), indicating the structural changes of the clusters in the bending coordinate upon ionization. The combination of the three kinds of spectroscopic methods provides the binding energies of cis and trans 3FNMA-Ar-1 clusters in the S-0, S-1 and D-0 states with good accuracy, and the values estimated by dispersion-corrected DFT calculations compare well with the experimental results. From our studies, the omega B97X-D and TD-omega B97X-D methods using high quality basis set are recommended for studying the intermolecular interaction of such vdW clusters in the ground and excited states. (C) 2017 Elsevier B.V. All rights reserved

High-resolution photofragment translational spectroscopy for the UV photodissociation of C2H5I

The photodissociation of ethyl iodide at 279.71, 281.73, 304.02 and 304.67 nm has been studied on our new mini-photofragment translational spectrometer with a total flight path of only 5 cm. Some vibrational peaks are firstly resolved in the TOF spectra of I*(P-2(1/2)) and I(P-2(3/2)) channels. These vibrational peaks are assigned to the excitation states (v(2) = 0, 1, 2,---) of the umbrella mode (v(2), 540 cm(-1)) of the photofragment CA, and the distribution of the vibrational states is obtained. The dissociation energy has been determined to be D-0(C-I)=2.314 +/- 0.03 eV. The energy partitioning of the available energy (E-avl=E-T+E-int = E-T+E-V,E-R) calculated from our experimental data E-int /E-avl = 22.1% at 281.73 nm, 22.4% at 304.02 nm for the I* channel, and E-int /E-avl = 25.2% at 279.71 nm, 25.9% at 304.67 nm for the I channel, seem to be more reliable

Photodissociation dynamics of ICH2Cl -> CH2Cl + I-star/I: photofragment translational spectroscopy at 304 and 277 nm

The photodissociation dynamics of ICH2Cl -> CH2Cl + I-star/I at 304 and 277 nm has been investigated with our mini-TOF photofragment translational spectrometer with a weak acceleration field of <1 V cm(-1). Many peaks are resolved or partially resolved in the TOF spectra and the photofragment translational spectra (PTS) of both the I-star(P-2(1/2)) channel and the I(P-2(3/2)) channel. These resolved peaks are assigned to the C-Cl stretch vibrational states of the CH2Cl fragment. The rotational energy E-R of the CH2Cl fragment is highly excited due to its asymmetric structure. The value of E-R/E-T is measured to be about 0.71. In the I-star channel, the partitioning of the available energy E-avl into the translational energy E-T, the rotational energy E-R, and the vibrational energy E-V for each resolved vibrational state has been calculated