飞机跑道胶痕的自动识别系统设计与实现

为了减轻机场跑道除胶工作人员的劳动强度,提高除胶工作效率,文章提出了一种基于机器视觉的胶痕自动查找和识别方法,设计了基于ARM单片机控制的图像无线采集和基于PC机控制的图像接收、图像预处理和图像识别系统。文章通过分析预处理后的数据特点,确定了基于细胞神经网络算法的胶痕识别算法,然后在MATLAB仿真环境下确定了该算法的最优模型和参数,最后在Visual C++ 6.0环境下完成了该算法的程序编译,调试并完成了对胶痕的自动识别过程。理论仿真和程序测试的结果证明了文章提出的方法在胶痕自动识别系统中的可行性,也为机场特种设备的无人化和智能化提供了参考。     

New physics hints in B decays and collider outlook

There are currently two hints for new physics involving CP violation in b → s transitions: ΔS ≡ S _f − S _J ^ϕK ≠ 0, and difference in direct CP asymmetry ΔA _Kπ ≡ A _K+π ⁰ − A _K+π ⁻ ≠ 0. We explore the two scenarios with a large and unique new CP phase in b ↔ s transitions. Motivated by ΔS ≠ 0, we update on the right-handed strange-beauty squark sb _1R at TeV scale. Motivated by ΔA _Kπ ≠ 0, we explore sequential fourth generation t′ and b′ quarks. Both scenarios can survive constraints such as SM level b → sγ, sll and B _s mixing, and predict sizable CP violation in B _s mixing. The fourth generation picture predicts sizable K _L → π ⁰ vv. Direct search for sb _R, b′ and t′ at hadronic colliders, such as Tevatron Run II and LHC, can complement further CP violation studies at these machines, as well as at the future Super B factory.     

Characterization and properties of ZnO1−xSx alloy films fabricated by radio-frequency magnetron sputtering

A series of ZnO_1−xS_x alloy films (0 ≤ x ≤ 1) were grown on quartz substrates by radio-frequency (rf) magnetron sputtering of ZnS ceramic target, using oxygen and argon as working gas. X-ray diffraction measurement shows that the ZnO_1−xS_x films have wurtzite structure with (0 0 2) preferential orientation in O-rich side (0 ≤ x ≤ 0.23) and zinc blende structure with (1 1 1) preferential orientation in S-rich side (0.77 ≤ x ≤ 1). However, when the S content is in the range of 0.23 < x < 0.77, the ZnO_1−xS_x film consists of two phases of wurtzite and zinc blende or amorphous ZnO_1−xS_x phase. The band gap energy of the films shows non-linear dependence on the S content, with an optical bowing parameter of about 2.9 eV. The photoluminescence (PL) measurement reveals that the PL spectrum of the wurtzite ZnO_1−xS_x is dominated by visible band and its PL intensity and intensity ratio of UV to visible band decrease greatly compared with undoped ZnO. All as-grown ZnO_1−xS_x films behave insulating, but show n-type conductivity for w-ZnO_1−xS_x and maintain insulating properties for β-ZnO_1−xS_x after annealed. Mechanisms of effects of S on optical and electrical properties of the ZnO_1−xS_x alloy are discussed in the present work.     

Study of the spectrum of CH335C1 between 4250 and 4600 CM?1: thev2+v4 andv4+v5 rovibrational bands

About 2500 lines of CH₃ ³⁵Cl have been assigned. The strong xy Coriolis resonance between thev ₂ andv ₅ modes is quite visible between thev ₄+v ₄ ^±1 perpendicular band, centered around 4383 cm^–1, and thev ₄ ^±1 +v ₅ ^±1 perpendicular component, centered around 4475 cm^–1, with a crossing of upper energy levels allowing the observation of lines which are normally forbidden. Although not yet observed with certainty, because of the great density of lines of the spectrum, thev ₄ ¹ +v ₅ ^±1 parallel component is nevertheless detectable by its effects onv ₂+v ₄ ^±1 which is linked by Coriolis resonance to both components ofv ₄+v ₅. Moreover the spectrum is much complicated by many other resonances with weak bands which occur at level crossings: it is the case ofv ₂+3v ₆ ^±1 , connected tov ₂+v ₄ ^±1 by the well known Darling Dennison resonance which couplesv ₄ ^±1 and 3v ₆ ^±1 , and also ofv ₅ ^±1 +3v ₆ ^±1 connected tov ₄ ^±1 +v ₅ ^±1 by the same resonance; but this last case is complicated by an anharmonic resonance betweenv ₅ ^±1 +3v ₆ ^±1 and 2v ₃+3v ₆ ¹ . Two more perturbations occur on the K=–1 side ofv ₂+v ₄: a weak Coriolis resonance gives rise to one subband ofv ₁+v ₂ at a level crossing withv ₂+v ₄, and thev ₁+v ₅ band (linked of course tov ₁+v ₂ by the Coriolis resonance between thev ₂ andv ₅ modes) is quite visible and perturbs several subbands ofv ₂+v ₄ of high values of K through an anharmonic resonance. Moreover, the complex (3v ₅ ^±1 ,v+2v ₅ ⁰ , 2v ₂+v ₅ ^±1 , 3v ₂,v ₂+2v ₅ ^±2 , 3v ₅ ^±3 ) system of Coriolis-connected bands is linked to the bands studied in the present work by two Fermi resonances: one betweenv ₂+2v ₅ ⁰ andv ₁+v ₂, and the other one betweenv ₁+v ₅ and 3v ₅ ^±1 , whose several subbands have been observed on the low part of the spectrum. The values of all the band centres and of the different coupling constants have been estimated, but all these interactions make the line assignments and the interpretation of the spectrum very difficult.     

On the Riemannian geometry of Seiberg–Witten moduli spaces

We construct a natural L²$L^2$-metric on the perturbed Seiberg–Witten moduli spaces _Mμ+${\mathfrak{M}}_{{\mu }^{+}}$ of a compact 4-manifold M$M$, and we study the resulting Riemannian geometry of _Mμ+${\mathfrak{M}}_{{\mu }^{+}}$. We derive a formula which expresses the sectional curvature of _Mμ+${\mathfrak{M}}_{{\mu }^{+}}$ in terms of the Green operators of the deformation complex of the Seiberg–Witten equations. In case M$M$ is simply connected, we construct a Riemannian metric on the Seiberg–Witten principal U(1)$U\left(1\right)$ bundle P→_Mμ+$\mathfrak{P}\to {\mathfrak{M}}_{{\mu }^{+}}$ such that the bundle projection becomes a Riemannian submersion. On a Kähler surface M$M$, the L²$L^2$-metric on _Mμ+${\mathfrak{M}}_{{\mu }^{+}}$ coincides with the natural Kähler metric on moduli spaces of vortices.     

First-principles materials design of CuInSe2-based high-efficiency photovoltaic solar cells

Based on ab initio   electronic structure calculations by self-interaction-corrected local-density-approximation (SIC-LDA) with the Korringa–Kohn–Rostoker coherent potential approximation (KKR-CPA), we propose a materials design for high efficiency photovoltaic solar cells (PVSCs). It is shown that (i) the concentration dependence of the mixing energy of CuIn_1−xGa_xSe₂${\mathrm{CuIn}}_{1-x}{\mathrm{Ga}}_x{\mathrm{Se}}_2$ shows upward convexity, thus this system favors phase separation. Due to the type II band alignment between CuInSe₂${\mathrm{CuInSe}}_2$ and CuGaSe₂${\mathrm{CuGaSe}}_2$, efficient electron–hole separation is realized in decomposed phase of this system. (ii) CuIn_1−xZn_0.5xSn_0.5xSe₂${\mathrm{CuIn}}_{1-x}{\mathrm{Zn}}_{0.5x}{\mathrm{Sn}}_{0.5x}{\mathrm{Se}}_2$ has a direct band gap and no impurity state appears in the gap. Therefore, cost reduction is possible by using Zn and Sn instead of In. (iii) n-type CuAl_1−xSn_xS₂${\mathrm{CuAl}}_{1-x}{\mathrm{Sn}}_x{\mathrm{S}}_2$ and p-type Cu_1−xV_CuxAlS₂${\mathrm{Cu}}_{1-x}{\mathrm{V}}_{\mathrm{Cu}x}{\mathrm{AlS}}_2$ have negative activation energy for doped impurities and are expected to be low-resistive transparent conducting sulfides, which should be useful for CuInSe₂${\mathrm{CuInSe}}_2$-based PVSCs.     

Multiple reflections from meteor trails and small-scale wind structure

Summary A new observational method for determining winds on extremely small scales in the upper mesosphere has been developed by radar observations of relatively rare, but long enduring trails of bright meteors, known as fireballs. The radar meteor system near Bologna enables to determine wind velocities at the points on the fireball trail, separated from each other in a time scale of 1 s and in a distance scale by 0.1 km. Results of investigation of the fireballs observed in Bologna during the EBC (Energy Budget Campaign) in November 1980, based on the analysis of multiple or double reflections from meteor trails show the variation of the wind velocity in very small areas. Fireball trains can provide several independent echoes, connected with the position, orientation, total duration of the trail and with the efficiency of the radar equipment used. More complex information on the atmospheric irregularities and on their occurrence can be derived during the observations of meteor showers, analysing simultaneously the motion of the effective reflection point on the trail from the range drift of echoes, and the Doppler shift wind measurements.

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Riassunto è stato sviluppato un nuovo metodo per determinare i venti nell'alta mesosfera su scale estremamente piccole, dall'osservazione radar di tracce di meteore luminose, relativamente rare e durevoli, conosciute come ?fireballs?. Il sistema radar di Budrio, nei pressi di Bologna, consente di determinare velocità del vento in punti sulla scia del fireball, separati nel tempo e nella distanza, rispettivamente di 1 secondo e di 0.1 km. I risultati di un'indagine sui fireballs osservati durante l'EBC (Energy Budget Campaign) nel novembre 1980, basata sull'analisi di riflessioni multiple da tracce di meteore, mostra che la velocità del vento varia su aree molto piccole. Le scie di fireballs possono fornire parecchi echi indipendenti associati, da una parte, alla posizione, orientazione e durata totale della traccia, e dall'altra, all'efficienza dell'apparato radar utilizzato. Informazioni più complesse su alcune irregolarità atmosferiche e sulla loro incidenza, possono essere desunte nel corso delle osservazioni di sciami di meteore, analizzando simultaneamente il moto del punto effettivo di riflessione sulla traccia (dalle deviazioni nelle distanze degli echi), nonché le misure Doppler di vento.

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Резюме Развивается новый метод для определения ветров с очень малыми масштабами в верхней мезосфере, используя радарные наблюдения относительно редких, но продолжительных хвостов ярких метеоров, известных как файерболы. Радарная система в Будрио, недалеко от Болоньи, позволяет определить скорости ветра в точках в кильваторе файербола, которые разделены друг от друга по времени в 1 секунду, а по расстоянию в 0.1 км. Результаты исследования файерболов, наблюденных в течение ЕВС, в ноябре 1980, основанные на анализе многократных отражений от метеорных хвостов, обнаруживают изменения скорости ветра в очень малых областях. Кильваторы файерболов могут образовывать несколько независимых эхо-сигналов, связанных, с одной стороны, с положением, ориентацией и полной длительностью хвоста, а, с другой стороны, с эффективностью используемого радарного оборудования. Более полную информацию об атмосферных нерегулярностях и их возникновении можно получить во время наблюдений метеорных ливней, анализируя одновременно движение эффективной точки отражения в хвосте (из дрейфа расстояния для эхо) и измерения ветра по доплеровскому сдвигу.

     

Optical and fluorescence spectroscopy of Eu2O3-doped P2O5-K2O-KF-MO-Al2O3 (M = Mg, Sr and Ba) glasses

Fluorophosphate glasses of composition, P₂O₅ + K₂O + KF + MO + Al₂O₃ + xEu₂O₃ (M = Mg, Sr and Ba; x = 0.01, 0.05, 0.1, 1.0, 2.0, 4.0 and 6.0 mol%) were prepared and characterized their optical properties. Crystal-field (CF) analysis revealed a relatively weak CF strength around Eu³⁺ ions in the Ba based fluorophosphate glasses. The Judd-Ofelt parameters have been estimated from the oscillator strengths of ⁷F₀ → ⁵D₂, ⁷F₀ → ⁵D₄ and ⁷F₀ → ⁵L₆ absorption transitions of Eu³⁺ ions and were used to evaluate the radiative properties of the ⁵D₀ → ⁷F_J (J = 0-4) transitions. Considerable variation has been observed in the relative intensity ratio of ⁵D₀ → ⁷F₂ to ⁵D₀ → ⁷F₁ transitions of Eu³⁺ ions due to change in the alkaline earth metal ions. The decay of the ⁵D₀ level shows single exponential and less sensitive to Eu³⁺ ions concentration as well as MgO/SrO/BaO modifiers.     

Inclusive production of the meson in hadronic decays of the Z boson

The inclusive production rate of the ρ^±(770) vector meson in hadronic Z decays is measured with the ALEPH detector at the LEP collider. A total of 3.2 million hadronic events are selected from data recorded between 1991 and 1995. Decays of ρ^±→π⁰+π^± are reconstructed for x_E>0.05 and x_p>0.05 where x_p=p_ρ/p_beam and x_E=E_ρ/E_beam. The average ρ^± multiplicity per hadronic event is evaluated to be N(ρ^±)=2.59±0.03±0.15±0.04 where the first error is statistical and the second systematic. The third error is from the uncertainty in the extrapolation to x_p=x_E=0. The rates and differential cross-section are compared with Monte Carlo model predictions and OPAL measurements. Residual Bose–Einstein correlations are found to be an important component in the analysis.     

Energy and line width in the induced emission of Mössbauer radiation

Summary Some promising schemes proposed for extending the range of lasers to the X-ray and gamma-ray regions are those involving a transition from a long-lived nuclear excited state. While metastable states allow the creation of conditions for population inversion, they also give rise to problems due to the narrowness of the expected line width. We discuss the line width of the radiation due to gamma transitions between excited states and derive a corrected relation for the cross-section in this case. Criteria for choosing an appropriate isotope are deduced from the corrected crosssection, showing that the problems derived from the narrowness of the line width can be avoided in a transition from an isomeric state to a lower short-lived excited state in which case the line width of the radiation is totally determined by the breadth of the lower excited state.

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Riassunto Alcuni schemi promettenti proposti per estendere il campo dei laser alle regioni dei raggi X e dei raggi gamma sono quelli che coinvolgono una transizione da uno stato eccitato nucleare a vita lunga. Mentre gli stati metastabili permettono la creazione delle condizioni per l’inversione della popolazione, essi danno luogo anche ai problemi dovuti alla ristrettezza dell’ampiezza della linea attesa. Si discute l’ampiezza di linea della radiazione dovuta alle transizioni gamma tra gli stati eccitati e si deduce una relazione corretta per la sezione d’urto in questo caso. Si deducono i criteri per scegliere un isotopo appropriato dalla sezione d’urto corretta, mostrando che i problemi che derivano dalla ristrettezza dell’ampiezza di linea si possono evitare in una transizione da uno stato isomerico a uno stato eccitato piú basso a vita breve, nel qual caso l’ampiezza di linea della radiazione si determina totalmente dalla larghezza dello stato eccitato piú basso.

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Резюме Были предложены обнадеживающие схемы для расширения области лазеров в рентгеновскую и гамма-области. Эти схемы вкяючают переход из долгоживущего ядерного возбужденного состояния. Так как метастабильные состояния допускают создание условий для инверсной заселенности, то они также приводят к проблемам, обусловленным узостью ожидаемой ширины линии. Мы обсуждаем ширину линии излучения, обусловленную гамма-переходами между возбужденными состояниями и выводим соотношение для поперечного сечения в этом случае. Выводятся критерии для выбора соответствующего изотопа из полученного поперечного сечения. Показывается, что проблемы, связанные с узостью ширины линии, можно обойти в случае перехода из изомерного состояния в низшее короткоживущее возбужденное состояние, причем в этом случае ширина линии излучения полностью определяется шириной низшего возбужденного состояния.

     

Weak ferromagnetism in BiFeO3 doped with titanium

The Bi_1−xA_xFe_1−xTi_xO₃ (A—Ca, Sr, Pb, Ba) and BiFe_1−xTi_xO_3+δ systems have been studied using X-ray, neutron powder diffraction and magnetization measurements in a magnetic field up to 14 T. It was found that all Bi_1−xA_xFe_1−xTi_xO₃ solid solutions are rhombohedral up to x=0.3. In the case of BiFe_1−xTi_xO_3+δ the rhombohedral distortion preserved up to x=0.11. A homogeneous weakly ferromagnetic state was found for Bi_1−xCa_xFe_1−xTi_xO₃ (0.15≤x≤0.25) and BiFe_1−xTi_xO_3+δ (0.06≤x≤0.11), probably due to magnetoelectric interactions, whereas Bi_1−xA_xFe_1−xTi_xO₃ (A—Sr, Pb, Ba) compounds above doping level x>0.1 seem to be collinear antiferromagnets.     

The absorption spectrum of phosphine (PH3) between 2.8 and 3.7 μm: Line positions, intensities, and assignments

Over 8000 line positions and intensities of phosphine (PH₃) at 3 μm have been measured at 0.0115 cm⁻¹ resolution with the McMath-Pierce Fourier Transform spectrometer at Kitt Peak. The observed line intensities ranged from 4.13 × 10⁻⁶ to 4.69 × 10⁻² cm⁻² atm⁻¹ at 296 K, for line positions between 2724.477 and 3601.652 cm⁻¹. This region spans eight interacting vibrational states: 3ν₂ (2940.8 cm⁻¹), 2ν₂ + ν₄ (3085.6 cm⁻¹), ν₂ + 2ν₄ (3214.9 cm⁻¹), ν₁ + ν₂ (3307.6 cm⁻¹), ν₂ + ν₃ (3310.5 cm⁻¹), 3ν₄ (∼3345 cm⁻¹), ν₁ + ν₄ (3426.9 cm⁻¹), and ν₃ + ν₄ (3432.9 cm⁻¹). Assignments have been determined for all the bands except 3ν₄ (a weak band in a highly congested area) for a total of 4232 transitions. The total integrated intensity for this region is 5.70 cm⁻² atm⁻¹ near 296 K, and assigned lines account for 79% of the observed absorption. The two strongest bands in the region are ν₁ + ν₄ and ν₃ + ν₄ with band strengths at 296 K of 1.61 and 2.01 cm⁻² atm⁻¹, respectively. An empirical database of PH₃ line parameters (positions, intensities, and assignments) is now available. Lower state energies (corresponding to assignments from this study) and line widths from the literature are included; default values are used for unassigned features.     

Ferromagnetic properties of Fe-substituted ZnO-based magnetic semiconductor

The diluted magnetic semiconductor Zn_1−x⁵⁷Fe_xO (x=0.01, 0.02, 0.03) compounds were prepared by the solid-state reaction method. The crystal structure of _Zn0.97⁵⁷_Fe0.03O${\mathrm{Zn}}_{0.97}{}^{57}{\mathrm{Fe}}_{0.03}\mathrm{O}$ at room temperature is determined to be a hexagonal structure of P6₃mc with lattice constants a₀=3.252 Å and c₀=5.205 Å by Rietveld refinement. The Bragg factors R_B and R_F were determined as 3.23% and 2.81%. From the inverse susceptibility versus T curve, the paramagnetic Curie temperature is found to be 2.7 K and effective moment is found to be 4.01 μ_B, thereby suggesting that the exchange interactions between Fe ions are ferromagnetic. Mössbauer spectra of _Zn0.97⁵⁷_Fe0.03O${\mathrm{Zn}}_{0.97}{}^{57}{\mathrm{Fe}}_{0.03}\mathrm{O}$ have been taken at various temperatures ranging from 4.2 to 295 K. Mössbauer spectrum for _Zn0.97⁵⁷_Fe0.03O${\mathrm{Zn}}_{0.97}{}^{57}{\mathrm{Fe}}_{0.03}\mathrm{O}$ at 4.2 K has shown ferromagnetic phase (sextet), and the spectra were fitted based on a random distribution model of Fe ions.     

Growth and spectroscopic characterization of Er: Sr3Y(BO3)3 crystal

This paper reports the growth and spectroscopic characterization of Er³⁺:Sr₃Y(BO₃)₃ crystal. Er³⁺:Sr₃Y(BO₃)₃ crystal with dimensions up to ∅20×35 mm³ has been grown by Czochralski method. The polarized spectroscopic properties of Er³⁺:Sr₃Y(BO₃)₃ crystal were investigated. Based on the Judd-Ofelt theory, the effective intensity parameters Ω_t were obtained: Ω₂=1.71×10⁻²⁰ cm², Ω₄=1.39×10⁻²⁰ cm², Ω₆=0.74×10⁻²⁰ cm² for π-polarization, and Ω₂=1.77×10⁻²⁰ cm², Ω₄=1.44×10⁻²⁰ cm², Ω₆=0.65×10⁻²⁰ cm² for σ-polarization. The emission cross-section σ_em was calculated to be 4.75×10⁻²¹ cm² for π-polarization at 1536 nm and 6.30×10⁻²¹ cm² for σ-polarization at 1537 nm. The investigated results showed that Er³⁺:Sr₃Y(BO₃)₃ crystal may be regarded as a potential laser host material for 1.55 μm IR solid-state lasers.     

SrBi2Ta2O9/Bi4Ti3O12复合铁电薄膜的制备与特性研究

采用溶胶凝胶工艺在p-Si衬底上制备了SrBi₂Ta₂O₉/Bi₄Ti₃O₁₂复合铁电薄膜. 研究了SrBi₂Ta₂O₉/Bi₄Ti₃O₁₂复合薄膜的微观结构与生长行为、铁电性能和疲劳特性. 研究表明: Si衬底Bi₄Ti< 关键词： 2Ta₂O₉')" href="#">SrBi₂Ta₂O₉ 4Ti₃O₁₂')" href="#">Bi₄Ti₃O₁₂ 复合铁电薄膜 溶胶凝胶工艺