A novel automatic ultrasonic system used for the inspection of pipeline girth welds is developed, in which a linear phased array transducer using electronic scan is adopted. Optimal array parameters are determined bas...A novel automatic ultrasonic system used for the inspection of pipeline girth welds is developed, in which a linear phased array transducer using electronic scan is adopted. Optimal array parameters are determined based on a mathematical model of acoustic field for linear phased array derived from Huygens' principle. The testing method and the system structure are introduced. The experimental results show that the phased array transducer system has the same detectability as that of conventional ultrasonic transducer system, but the system architecture can be simplified greatly, and the testing flexibility and the testing speed can be improved greatly.展开更多
The work presented in this paper concerns with analysis and synthesis of the two-dimensional Infinite Impulse Response (IIR) filters based on model order reduction. The synthesis is performed with two methods, the Pro...The work presented in this paper concerns with analysis and synthesis of the two-dimensional Infinite Impulse Response (IIR) filters based on model order reduction. The synthesis is performed with two methods, the Prony's method (Prony modified) and Iterative method, in the spatial domain, and with the method of Semi-Definite iterative Programming (SDP), in the frequency domain. After synthesis, we make an order reduction of the filter model by the Quasi-Gramians method.展开更多
Based on the study of phase angle and wavelength in pBRDF (Polarized bidirectional reflectance distribution function), roujean model was proposed to describe Orient (Polarization phase angle) quantitatively. The Rouje...Based on the study of phase angle and wavelength in pBRDF (Polarized bidirectional reflectance distribution function), roujean model was proposed to describe Orient (Polarization phase angle) quantitatively. The Roujean model was used to quantitatively describe different fruits intensity components (<i><span style="font-family:Verdana;font-size:12px;">F</span></i><sub><span style="font-family:Verdana;font-size:12px;vertical-align:sub;">00</span></sub><span style="font-family:Verdana;font-size:12px;">) and polarization phase angle (Orient), and the simulation results were analyzed and compared using statistical analysis and comparison methods to realize the prediction from the regular model to the outdoor fruit tree canopy to the canopy of outdoor fruit tree canopy random distribution. The experimental results showed that: 1) when the phase angle of jujube was 52.19<span style="white-space:nowrap;">°</span>, 66.51<span style="white-space:nowrap;">°</span></span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">and 88.26<span style="white-space:nowrap;">°</span>, the </span><i><span style="font-family:Verdana;font-size:12px;">R</span></i><sup><span style="font-family:Verdana;font-size:12px;vertical-align:super;">2</span></sup><span style="font-family:Verdana;font-size:12px;"> and average errors of </span><i><span style="font-family:Verdana;font-size:12px;">F</span></i><sub><span style="font-family:Verdana;font-size:12px;vertical-align:sub;">00</span></sub><span style="font-family:Verdana;font-size:12px;"> parameters described by Roujean model are 0.9982, 0.9963, 0.9912 and 3.80%, 4.17%, 6.40%, respectively;</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">a</span><span style="font-family:Verdana;font-size:12px;">nd the </span><i><span style="font-family:Verdana;font-size:12px;">R</span></i><sup><span style="font-family:Verdana;font-size:12px;vertical-align:super;">2</span></sup><span style="font-family:Verdana;font-size:12px;"> and average error of Orient parameters described by Roujean model are 0.9056,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">0.9223,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">0.9260 and 6.23%,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">3.32%,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">8.05%, respectively;It can be seen that roujean model can quantitatively describe the Orient parameter of jujube</span><span style="font-family:Verdana;font-size:12px;">;</span><span style="font-family:Verdana;font-size:12px;">2) When the phase angle of apricot was 70.99<span style="white-space:nowrap;">°</span>, 71.28<span style="white-space:nowrap;">°</span> and 67.91<span style="white-space:nowrap;">°</span>, the </span><i><span style="font-family:Verdana;font-size:12px;">R</span></i><sup><span style="font-family:Verdana;font-size:12px;vertical-align:super;">2</span></sup><span style="font-family:Verdana;font-size:12px;"> and average errors of </span><i><span style="font-family:Verdana;font-size:12px;">F</span></i><sub><span style="font-family:Verdana;font-size:12px;vertical-align:sub;">00</span></sub><span style="font-family:Verdana;font-size:12px;"> parameters described by Roujean model </span><span style="font-family:Verdana;font-size:12px;">is</span><span style="font-family:Verdana;font-size:12px;"> 0.9862, 0.9823, 0.9792 and 3.40%,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">4.82%,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">5.19%, respectively;</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">And the R</span><sup><span style="font-family:Verdana;font-size:12px;vertical-align:super;">2</span></sup><span style="font-family:Verdana;font-size:12px;"> and average error of Orient parameters described by Roujean model are 0.9382, 0.8947, 0.8849 and 7.19%, 9.28%, 9.47%, respectively.</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">Roujean model can also quantitatively describe the Orient parameter of white apricot. In summary, the Roujean model can provide a good quantitative description of </span><i><span style="font-family:Verdana;font-size:12px;">f</span></i><sub><span style="font-family:Verdana;font-size:12px;vertical-align:sub;">00</span></sub><span style="font-family:Verdana;font-size:12px;"> and a good quantitative description of Orient, which in turn can predict the pBRDF parameter for more fruits with different incidence and detection directions.</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">It can correct the influence of angle factor in the nondestructive testing of outdoor fruits.</span>展开更多
The pattern of isentropes in the vicinity of a first-order phase transition is proposed as a key for a sub-classification. While the confinement-deconfinement transition, conjectured to set in beyond a critical end po...The pattern of isentropes in the vicinity of a first-order phase transition is proposed as a key for a sub-classification. While the confinement-deconfinement transition, conjectured to set in beyond a critical end point in the QCD phase diagram, is often related to an entropic transition and the apparently settled gas-liquid transition in nuclear matter is an enthalphic transition, the conceivable local isentropes w.r.t. “incoming” or “outgoing” serve as another useful guide for discussing possible implications, both in the presumed hydrodynamical expansion stage of heavy-ion collisions and the core-collapse of supernova explosions. Examples, such as the quark-meson model and two-phase models, are shown to distinguish concisely the different transitions.展开更多
文摘A novel automatic ultrasonic system used for the inspection of pipeline girth welds is developed, in which a linear phased array transducer using electronic scan is adopted. Optimal array parameters are determined based on a mathematical model of acoustic field for linear phased array derived from Huygens' principle. The testing method and the system structure are introduced. The experimental results show that the phased array transducer system has the same detectability as that of conventional ultrasonic transducer system, but the system architecture can be simplified greatly, and the testing flexibility and the testing speed can be improved greatly.
文摘The work presented in this paper concerns with analysis and synthesis of the two-dimensional Infinite Impulse Response (IIR) filters based on model order reduction. The synthesis is performed with two methods, the Prony's method (Prony modified) and Iterative method, in the spatial domain, and with the method of Semi-Definite iterative Programming (SDP), in the frequency domain. After synthesis, we make an order reduction of the filter model by the Quasi-Gramians method.
文摘Based on the study of phase angle and wavelength in pBRDF (Polarized bidirectional reflectance distribution function), roujean model was proposed to describe Orient (Polarization phase angle) quantitatively. The Roujean model was used to quantitatively describe different fruits intensity components (<i><span style="font-family:Verdana;font-size:12px;">F</span></i><sub><span style="font-family:Verdana;font-size:12px;vertical-align:sub;">00</span></sub><span style="font-family:Verdana;font-size:12px;">) and polarization phase angle (Orient), and the simulation results were analyzed and compared using statistical analysis and comparison methods to realize the prediction from the regular model to the outdoor fruit tree canopy to the canopy of outdoor fruit tree canopy random distribution. The experimental results showed that: 1) when the phase angle of jujube was 52.19<span style="white-space:nowrap;">°</span>, 66.51<span style="white-space:nowrap;">°</span></span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">and 88.26<span style="white-space:nowrap;">°</span>, the </span><i><span style="font-family:Verdana;font-size:12px;">R</span></i><sup><span style="font-family:Verdana;font-size:12px;vertical-align:super;">2</span></sup><span style="font-family:Verdana;font-size:12px;"> and average errors of </span><i><span style="font-family:Verdana;font-size:12px;">F</span></i><sub><span style="font-family:Verdana;font-size:12px;vertical-align:sub;">00</span></sub><span style="font-family:Verdana;font-size:12px;"> parameters described by Roujean model are 0.9982, 0.9963, 0.9912 and 3.80%, 4.17%, 6.40%, respectively;</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">a</span><span style="font-family:Verdana;font-size:12px;">nd the </span><i><span style="font-family:Verdana;font-size:12px;">R</span></i><sup><span style="font-family:Verdana;font-size:12px;vertical-align:super;">2</span></sup><span style="font-family:Verdana;font-size:12px;"> and average error of Orient parameters described by Roujean model are 0.9056,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">0.9223,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">0.9260 and 6.23%,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">3.32%,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">8.05%, respectively;It can be seen that roujean model can quantitatively describe the Orient parameter of jujube</span><span style="font-family:Verdana;font-size:12px;">;</span><span style="font-family:Verdana;font-size:12px;">2) When the phase angle of apricot was 70.99<span style="white-space:nowrap;">°</span>, 71.28<span style="white-space:nowrap;">°</span> and 67.91<span style="white-space:nowrap;">°</span>, the </span><i><span style="font-family:Verdana;font-size:12px;">R</span></i><sup><span style="font-family:Verdana;font-size:12px;vertical-align:super;">2</span></sup><span style="font-family:Verdana;font-size:12px;"> and average errors of </span><i><span style="font-family:Verdana;font-size:12px;">F</span></i><sub><span style="font-family:Verdana;font-size:12px;vertical-align:sub;">00</span></sub><span style="font-family:Verdana;font-size:12px;"> parameters described by Roujean model </span><span style="font-family:Verdana;font-size:12px;">is</span><span style="font-family:Verdana;font-size:12px;"> 0.9862, 0.9823, 0.9792 and 3.40%,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">4.82%,</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">5.19%, respectively;</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">And the R</span><sup><span style="font-family:Verdana;font-size:12px;vertical-align:super;">2</span></sup><span style="font-family:Verdana;font-size:12px;"> and average error of Orient parameters described by Roujean model are 0.9382, 0.8947, 0.8849 and 7.19%, 9.28%, 9.47%, respectively.</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">Roujean model can also quantitatively describe the Orient parameter of white apricot. In summary, the Roujean model can provide a good quantitative description of </span><i><span style="font-family:Verdana;font-size:12px;">f</span></i><sub><span style="font-family:Verdana;font-size:12px;vertical-align:sub;">00</span></sub><span style="font-family:Verdana;font-size:12px;"> and a good quantitative description of Orient, which in turn can predict the pBRDF parameter for more fruits with different incidence and detection directions.</span><span style="font-family:Verdana;font-size:12px;"> </span><span style="font-family:Verdana;font-size:12px;">It can correct the influence of angle factor in the nondestructive testing of outdoor fruits.</span>
基金jointly supported by the National Nature Science Foundation of China [grant number 42088101]NOAA [grant number NA18OAR4310298]+2 种基金the National Science Foundation (United States)[grant number AGS-2006553]the Educational Commission of Anhui Province of China [grant numbers KJ2021A1079 and KJ2021A1078]the Science and technology project of Chuzhou City of China [grant number 2021ZD007]。
文摘The pattern of isentropes in the vicinity of a first-order phase transition is proposed as a key for a sub-classification. While the confinement-deconfinement transition, conjectured to set in beyond a critical end point in the QCD phase diagram, is often related to an entropic transition and the apparently settled gas-liquid transition in nuclear matter is an enthalphic transition, the conceivable local isentropes w.r.t. “incoming” or “outgoing” serve as another useful guide for discussing possible implications, both in the presumed hydrodynamical expansion stage of heavy-ion collisions and the core-collapse of supernova explosions. Examples, such as the quark-meson model and two-phase models, are shown to distinguish concisely the different transitions.