With an increase in the density of the seed roll in the roll box of the saw gin, the quality indicators of the fiber and seed are poor, energy consumption increases, machine breakdowns increase, and when the density d...With an increase in the density of the seed roll in the roll box of the saw gin, the quality indicators of the fiber and seed are poor, energy consumption increases, machine breakdowns increase, and when the density decreases, the performance of the saw gin increases. Therefore, the density control of the seed roll is one of the important problems in the ginning process. The paper proposes a change in the rotation speed of the saw cylinder with a decrease in the diameter of its numerical linear speed and machine productivity. The article describes the problem of regulating the density of a seed roll in a saw gin of the DP series, provides an overview of work on regulating the operation of the machine, determines the dependence of the productivity of gins and linters on the state of the saw system in these machines, as well as changes in the linear speed of the saw by changing its diameter. Also, the critical speed of the gin and linter saw cylinder was determined to prevent resonance. In this case, the Simulation package of the SolidWorks computer program was used. The results of the study made it possible to adjust the speed of the cylinders when changing the diameter of the saws, which improved the productivity of the machine while maintaining the quality of the fiber and seed.展开更多
Progress of the ^40Ca^+ion optical clock based on the 4^2S1/2-3d ^2D5/2 electric quadrupole transition is reported.By setting the drive frequency to the“magic”frequencyΩ0,the frequency uncertainty caused by the scal...Progress of the ^40Ca^+ion optical clock based on the 4^2S1/2-3d ^2D5/2 electric quadrupole transition is reported.By setting the drive frequency to the“magic”frequencyΩ0,the frequency uncertainty caused by the scalar Stark shift and second-order Doppler shift induced by micromotion is reduced to the 10^-19 level.By precisely measuring the differential static scalar polarizability∆α0,the uncertainty due to the blackbody radiation(BBR)shift(coefficient)is reduced to the 10^-19 level.With the help of a second-order integrating servo algorithm,the uncertainty due to the servo error is reduced to the 10^-18 level.The total fractional uncertainty of the ^40Ca^+ion optical clock is then improved to 2.2×10^-17,whereas this value is mainly restricted by the uncertainty of the BBR shift due to temperature fluctuations.The state preparation is introduced together with improvements in the pulse sequence,and furthermore,a better signal to noise ratio(SNR)and less dead time are achieved.The clock stability of a single clock is improved to 4.8×10^-15√τ(in seconds).展开更多
This work deals with determining the optimum thickness of the base of an n<sup>+</sup>/p/p<sup>+</sup> silicon solar cell under monochromatic illumination in frequency modulation. The continuit...This work deals with determining the optimum thickness of the base of an n<sup>+</sup>/p/p<sup>+</sup> silicon solar cell under monochromatic illumination in frequency modulation. The continuity equation for the density of minority carriers generated in the base, by a monochromatic wavelength illumination (<i>λ</i>), with boundary conditions that impose recombination velocities (<i>Sf</i>) and (<i>Sb</i>) respectively at the junction and back surface, is resolved. The ac photocurrent is deduced and studied according to the recombination velocity at the junction, to extract the mathematical expressions of recombination velocity (<i>Sb</i>). By the graphic technique of comparing the two expressions obtained, depending on the thickness (<i>H</i>) of the base, for each frequency, the optimum thickness (Hopt) is obtained. It is then modeled according to the frequency, at the long wavelengths of the incident light. Thus, Hopt decreases due to the low relaxation time of minority carriers, when the frequency of modulation of incident light increases.展开更多
In order to understand the relationship between breakfast frequency and academic performance of grade 5 and grade 8 students, we conducted an investigation through a multistage cluster sampling design with 16,840 stud...In order to understand the relationship between breakfast frequency and academic performance of grade 5 and grade 8 students, we conducted an investigation through a multistage cluster sampling design with 16,840 students (8017 5th graders and 8823 8th graders) from Mianyang city. Results show that: 1) 71.3% of fifth graders and 59.7% of eighth graders had breakfast every day of the week, and 9.7% of fifth graders and 7.5% of eighth graders had breakfast three times or less per week. 2) The number of times students eat breakfast per week has a significant impact on their comprehensive academic performance, which is reflected in the trend that the more times students eat breakfast, the better their overall academic performance is. Based on this, in order to help students eat breakfast more often, and further improve students’ academic performance, we will strengthen the publicity and education of students’ breakfast knowledge from multiple perspectives.展开更多
<strong>Objectives:</strong> The goal was to assess the risk factors for emergency cesarean section versus prophylactic caesarean section. <strong>Materials and Methods:</strong> This was a des...<strong>Objectives:</strong> The goal was to assess the risk factors for emergency cesarean section versus prophylactic caesarean section. <strong>Materials and Methods:</strong> This was a descriptive analytical cross-sectional study of the Type Cas/Witnesses at the Reference Health Centre of Commune V of the District of Bamako in Mali. The sample consisted of 100 cases for 200 controls (1 case for 2 controls) with retrospective collection of data for the period from January 1 to July 11, 2011 (6 months and 11 days). <strong>Results:</strong> During the study period, out of a total of 3559 deliveries, we recorded 2,794 vaginal deliveries, 78.50% and 765 caesarean sections or 21.50%. Of the 765ceras, we performed 353 emergency caesarean sections or 46.15% and 412 prophylactic caesarean sections 53.85%. We have selected 100 prophylactic caesarean section files and 200 emergency caesarean section files. The average age of the patients was 27.41 years-5.84 with extreme ages of 14 to 40 years. 100% of our patients (Cas) had performed at least one antenatal consultation compared to 83.5% of the parturients evacuated (Witnesses). The most frequently cited reasons for evacuation were: acute fetal suffering, non-cephalic presentation and excessive uterine height with 30%, 17.5% and 12% respectively. The bulk of the caesarean section indications were dominated by dystocies with 90% in cases compared to 65% in Witnesses, followed by acute fetal suffering with 30% in Witnesses. We recorded 30% perinatal deaths among Witnesses compared to 1% in Cases. We recorded 16 uterine ruptures in the Witnesses among which 2 hysterectomies and 14 hystererraphia. <strong>Conclusion:</strong> Prophylactic caesarean section improves maternal and perinatal prognosis more than emergency caesarean section.展开更多
The modelling and determination of the geometric parameters of a solar cell are important data, which influence the evaluation of its performance under specific operating conditions, as well as its industrial developm...The modelling and determination of the geometric parameters of a solar cell are important data, which influence the evaluation of its performance under specific operating conditions, as well as its industrial development for a low cost. In this work, an n+/p/p+ crystalline silicon solar cell is studied under monochromatic illumination in modulation and placed in a constant magnetic field. The minority carriers’ diffusion coefficient (<em>D</em>(<em>ω</em>, <em>B</em>), in the (<em>p</em>) base leads to maximum values (Dmax) at resonance frequencies (<em>ωr</em>). These values are used in expressions of AC minority carriers recombination velocity (Sb(Dmax, H)) in the rear of the base, to extract the optimum thickness while solar cell is subjected to these specific conditions. Optimum thickness modelling relationships, depending respectively on Dmax, <em>ωr</em> and <em>B</em>, are then established, and will be data for industrial development of low-cost solar cells for specific use.展开更多
A theory employing the vortex shape of the electron was presented to resolve the enigma of the wave-particle duality. Conventions such as “particle” and “wave” were used to describe the behavior of quantum objects...A theory employing the vortex shape of the electron was presented to resolve the enigma of the wave-particle duality. Conventions such as “particle” and “wave” were used to describe the behavior of quantum objects such as electrons. A superfluid vacuum formed the base to describe the basic vortex structure and properties of the electron, whereas various formulations derived from hydrodynamic laws described the electron vortex circumference, radius, angular velocity and angular frequency, angular momentum (spin) and magnetic momentum. A vortex electron fully explained the associations between momentum and wave, and hydrodynamic laws were essential in deriving the energy and angular frequency of the electron. In general, an electron traveling in space possesses internal and external motions. To derive the angular frequency of its internal motion, the Compton wavelength was used to represent the length of one cycle of the internal motion that is equal to the circumference of the electron vortex. The angular frequency of the electron vortex was calculated to obtain the same value according to Planck’s theory. A traveling vortex electron has internal and external motions that create a three-dimensional helix trajectory. The magnitude of the instantaneous velocity of the electron is the resultant of its internal and external velocities, being equal to the internal velocity reduced by the Lorentz factor (whose essence is presented in a detailed formulation). The wavelength of the helix trajectory represents the distance traveled by a particle along its axis during one period of revolution around the axis, resulting in the same de Broglie wavelength that corresponds to the helix pitch of the helix. Mathematical formulations were presented to demonstrate the relation between the energy of the vortex and its angular frequency and de Broglie’s wavelength;furthermore, Compton’s and de Broglie’s wavelengths were also differentiated.展开更多
Recently, introduction of renewable energy sources like wind power generation and photovoltaic power generation has been increasing from the viewpoint of environmental problems. However, renewable energy power supplie...Recently, introduction of renewable energy sources like wind power generation and photovoltaic power generation has been increasing from the viewpoint of environmental problems. However, renewable energy power supplies have unstable output due to the influence of weather conditions such as wind speed variations, which may cause fluctuations of voltage and frequency in the power system. This paper proposes fuzzy PD based virtual inertia control system to decrease frequency fluctuations in power system caused by fluctuating output of renewable energy sources. The proposed new method is based on the coordinated control of HVDC interconnection line and battery, and energy balancing control is also incorporated in it. Finally, it is concluded that the proposed system is very effective for suppressing the frequency fluctuations of the power system due to the large-scale wind power generation and solar power generation and also for keeping the energy balancing in the HVDC transmission line.展开更多
Magnetic resonance elastography (MRE) can visualize the shear wave propagation of in vivo tissues, which can be mapped into viscoelastic properties. No study has measured the biomechanical properties of the PM muscle ...Magnetic resonance elastography (MRE) can visualize the shear wave propagation of in vivo tissues, which can be mapped into viscoelastic properties. No study has measured the biomechanical properties of the PM muscle in vivo using MRE. In this study, we evaluated stiffness values calculated by local frequency estimate (LFE) and algebraic inversion of differential equation (AIDE) in PM-MRE. The PM muscles of 17 healthy male volunteers were scanned in supine position by MRE. The Laplacian-based estimate (LBE) phase wrapped image data were filtered by gaussian-bandpass filter (GBF), and by both directional and GBF. LFE (MREWave) and AIDE wave inversion methods were used to calculate the respective elastograms. The wave interferences were removed by directional filtering, and smooth wave fields were obtained. The stiffness values calculated by LFE of non-DF images were 1.39 ± 0.25 kPa and 1.33 ± 0.22 kPa for right and left PM respectively, whereas for DF images, they were 1.26 ± 0.20 kPa for right PM and 1.18 ± 0.28 kPa for left PM. The stiffness values calculated by AIDE of non-DF images were 0.78 ± 0.10 kPa and 0.78 ± 0.13 kPa for right and left PM respectively, whereas for DF images, they were 0.73 ± 0.12 kPa for right PM and 0.74 ± 0.11 kPa for left PM. There was no statistically significant difference in mean values of stiffness with/without applying directional filter whereas there was a statistically significant difference in mean values of stiffness between LFE and AIDE. Both LFE and AIDE could be used for psoas major MR Elastography.展开更多
This paper studies the adaptive beamforming algorithm based on the frequency diverse array(FDA)array where the interference is located at the same angle(but different range)with the target.We take the cross subarray-b...This paper studies the adaptive beamforming algorithm based on the frequency diverse array(FDA)array where the interference is located at the same angle(but different range)with the target.We take the cross subarray-based FDA with sinusoidal frequency offset(CSB sin-FDA)as the receiving array instead of the basic FDA.The sampling covariance matrix under insufficient snapshot can be corrected by the automatic diagonal loading method.On the basis of decomposing the mismatched steering vector error into a vertical component and a parallel one,this paper searches the vertical component of the error by the quadratic constraint method.The numerical simulation verifies that the beamformer based on the CSB sin-FDA can effectively hold the mainlobe at the target position when the snapshot is insufficient or the steering vector is mismatched.展开更多
In this study, our goal is to obtain the entanglement dynamics of trapped three-level ion interaction two laser beams in beyond Lamb-Dicke parameters. Three values of LDP, <span style="white-space:nowrap;"...In this study, our goal is to obtain the entanglement dynamics of trapped three-level ion interaction two laser beams in beyond Lamb-Dicke parameters. Three values of LDP, <span style="white-space:nowrap;"><em>η</em>=0.09, <span style="white-space:nowrap;"><em>η</em>=0.2 </span></span>and <span style="white-space:nowrap;"><em>η</em>=0.3 </span>are given. We used the concurrence and the negativity to measure the amount of quantum entanglement created in the system. The interacting trapped ion led to the formation of phonons as a result of the coupling. In two quantum systems (ion-phonons), analytical formulas describing both these measurements are constructed. These formulas and probability coefficients include first order terms of final state vector. We report that long survival time of entanglement can be provided with two quantum measures. Negativity and concurrence maximum values are obtained N = 0.553 and for LDP = 0.3. As a similar, the other two values of LDP are determined and taken into account throughout this paper. For a more detailed understanding of entanglement measurement results, “contour plot” was preferred in Mathematica 8.展开更多
A 1.5 GHz passive third harmonic superconducting cavity was proposed to improve the beam quality and lifetime in the Shanghai Synchrotron Radiation Facility Phase-II beamline project.Lifetime improvement highly depend...A 1.5 GHz passive third harmonic superconducting cavity was proposed to improve the beam quality and lifetime in the Shanghai Synchrotron Radiation Facility Phase-II beamline project.Lifetime improvement highly depends on the resonant frequency of the passive third harmonic superconducting cavity.It is important that the operating frequency of the cavity is within the design range and the cavity has reasonable mechanical stability.A simulation method for the multiphysics coupled analysis has been developed based on the ANSYS code.Multiphysics coupled simulations have been performed under different conditions,such as etching,evacuation,cooling,and preloading.Analyses of mechanical modes and structural stress have been executed.A possible stiffening ring method for the two-cell superconducting niobium cavity has been investigated.In this paper,we present a multiphysics coupled analysis of the third harmonic cavity using a finite element analysis code.The results of the analysis show that a reliable frequency for the cavity after electron beam welding is 1498.033 MHz,and the corresponding frequency of the pre-tuning goal is 1496.163 MHz.A naked cavity is a reasonable option based on structural stress and mechanical modal analyses.A frequency range of±500 kHz and limiting tolerable displacement of±0.35 mm are proposed for the design of the frequency tuner.展开更多
In order to improve the electrical and frequency characteristics of SiGe heterojunction bipolar transistors (HBTs), a novel structure of SOI SiGe heterojunction bipolar transistor is designed in this work. Compared wi...In order to improve the electrical and frequency characteristics of SiGe heterojunction bipolar transistors (HBTs), a novel structure of SOI SiGe heterojunction bipolar transistor is designed in this work. Compared with traditional SOI SiGe HBT, the proposed device structure has smaller window widths of emitter and collector areas. Under the act of additional uniaxial stress induced by Si0.85Ge0.15, all the collector region, base region and emitter region are strained, which is beneficial to improve the performance of SiGe HBTs. Employing the SILVACOⓇTCAD tools, the numerical simulation results show that the maximum current gain βmax, the Earley voltage VA are achieved for 1062 and 186 V, respectively, the product of β and VA, i.e., β ×VA, is 1.975 × 105 V and, the peak cutoff frequency fT is 419 GHz when the Ge component in the base has configured to be a trapezoidal distribution. The proposed SOI SiGe HBT architecture has a 52.9% improvement in cutoff frequency fT compared to the conventional SOI SiGe HBTs.展开更多
The discovery of a data based informational wave pattern infuses coherent entanglement into the system. This discovery of how to add coherent entanglement into the model provides the missing key, that has opened the d...The discovery of a data based informational wave pattern infuses coherent entanglement into the system. This discovery of how to add coherent entanglement into the model provides the missing key, that has opened the door to understanding the universe. It is found that the inclusion of coherence and entanglement at the start of the system is extremely simple and in fact it is so simple that it has simply been overlooked. Entanglement and coherence are the most fundamental aspects of our universe. It is demonstrated that the basic model of the hydrogen atom is made from the CMB. If we add entanglement into this basic model of the hydrogen atom a math system called Wave Pattern Entangled Math is unveiled. This system of wave interference mathematics creates a data system in which entanglement and coherence can easily be understood. The final outcome is an unbreakable pattern of information, including entangled energy, entropy, spin, universal expansion, compression, velocity of light, C2, and Quantum Coherence.展开更多
Despite their high manufacturing cost and structural deficiencies especially in tip regions,highly skewed propellers are preferred in the marine industry,where underwater noise is a significant design criterion.Howeve...Despite their high manufacturing cost and structural deficiencies especially in tip regions,highly skewed propellers are preferred in the marine industry,where underwater noise is a significant design criterion.However,hydrodynamic performances should also be considered before a decision to use these propellers is made.This study investigates the trade-off between hydrodynamic and hydroacoustic performances by comparing conventional and highly skewed Seiun Maru marine propellers for a noncavitating case.Many papers in the literature focus solely on hydroacoustic calculations for the open-water case.However,propulsive characteristics are significantly different when propeller-hull interactions take place.Changes in propulsion performance also reflect on the hydroacoustic performances of the propeller.In this study,propeller-hull interactions were considered to calculate the noise spectra.Rather than solving the full case,which is computationally demanding,an indirect approach was adopted;axial velocities from the nominal ship wake were introduced as the inlet condition of the numerical approach.A hybrid method based on the acoustic analogy was used in coupling computational fluid dynamics techniques with acoustic propagation methods,implementing the Ffowcs Williams-Hawkings(FW-H)equation.The hydrodynamic performances of both propellers were presented as a preliminary study.Propeller-hull interactions were included in calculations after observing good accordance between our results,experiments,and quasi-continuous method for the open-water case.With the use of the time-dependent flow field data of the propeller behind a nonuniform ship wake as an input,simulation results were used to solve the FW-H equation to extract acoustic pressure and sound pressure levels for several hydrophones located in the near field.Noise spectra results confirm that the highest values of the sound pressure levels are in the low-frequency range and the first harmonics calculated by the present method are in good accordance with the theor展开更多
From resolution of two-dimensional equation of heat in dynamic frequency regime, we have plotted evolution curves of temperature according to depth of material or in lateral direction. They will allow us to evaluate t...From resolution of two-dimensional equation of heat in dynamic frequency regime, we have plotted evolution curves of temperature according to depth of material or in lateral direction. They will allow us to evaluate thermal behavior of towed material. Aim of study is to use fibers as a thermal insulating material by proposing a method for determining effective thermal insulation layer in dynamic frequency regime.展开更多
文摘With an increase in the density of the seed roll in the roll box of the saw gin, the quality indicators of the fiber and seed are poor, energy consumption increases, machine breakdowns increase, and when the density decreases, the performance of the saw gin increases. Therefore, the density control of the seed roll is one of the important problems in the ginning process. The paper proposes a change in the rotation speed of the saw cylinder with a decrease in the diameter of its numerical linear speed and machine productivity. The article describes the problem of regulating the density of a seed roll in a saw gin of the DP series, provides an overview of work on regulating the operation of the machine, determines the dependence of the productivity of gins and linters on the state of the saw system in these machines, as well as changes in the linear speed of the saw by changing its diameter. Also, the critical speed of the gin and linter saw cylinder was determined to prevent resonance. In this case, the Simulation package of the SolidWorks computer program was used. The results of the study made it possible to adjust the speed of the cylinders when changing the diameter of the saws, which improved the productivity of the machine while maintaining the quality of the fiber and seed.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0304401,2018YFA0307500,2017YFA0304404,and 2017YFF0212003)the National Natural Science Foundation of China(Grant Nos.11622434,11774388,11634013,11934014,and 91736310)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB21030100)the CAS Youth Innovation Promotion Association(Grant Nos.Y201963 and 2018364)the Science Fund for Distinguished Young Scholars of Hubei Province,China(Grant No.2017CFA040).
文摘Progress of the ^40Ca^+ion optical clock based on the 4^2S1/2-3d ^2D5/2 electric quadrupole transition is reported.By setting the drive frequency to the“magic”frequencyΩ0,the frequency uncertainty caused by the scalar Stark shift and second-order Doppler shift induced by micromotion is reduced to the 10^-19 level.By precisely measuring the differential static scalar polarizability∆α0,the uncertainty due to the blackbody radiation(BBR)shift(coefficient)is reduced to the 10^-19 level.With the help of a second-order integrating servo algorithm,the uncertainty due to the servo error is reduced to the 10^-18 level.The total fractional uncertainty of the ^40Ca^+ion optical clock is then improved to 2.2×10^-17,whereas this value is mainly restricted by the uncertainty of the BBR shift due to temperature fluctuations.The state preparation is introduced together with improvements in the pulse sequence,and furthermore,a better signal to noise ratio(SNR)and less dead time are achieved.The clock stability of a single clock is improved to 4.8×10^-15√τ(in seconds).
文摘This work deals with determining the optimum thickness of the base of an n<sup>+</sup>/p/p<sup>+</sup> silicon solar cell under monochromatic illumination in frequency modulation. The continuity equation for the density of minority carriers generated in the base, by a monochromatic wavelength illumination (<i>λ</i>), with boundary conditions that impose recombination velocities (<i>Sf</i>) and (<i>Sb</i>) respectively at the junction and back surface, is resolved. The ac photocurrent is deduced and studied according to the recombination velocity at the junction, to extract the mathematical expressions of recombination velocity (<i>Sb</i>). By the graphic technique of comparing the two expressions obtained, depending on the thickness (<i>H</i>) of the base, for each frequency, the optimum thickness (Hopt) is obtained. It is then modeled according to the frequency, at the long wavelengths of the incident light. Thus, Hopt decreases due to the low relaxation time of minority carriers, when the frequency of modulation of incident light increases.
文摘In order to understand the relationship between breakfast frequency and academic performance of grade 5 and grade 8 students, we conducted an investigation through a multistage cluster sampling design with 16,840 students (8017 5th graders and 8823 8th graders) from Mianyang city. Results show that: 1) 71.3% of fifth graders and 59.7% of eighth graders had breakfast every day of the week, and 9.7% of fifth graders and 7.5% of eighth graders had breakfast three times or less per week. 2) The number of times students eat breakfast per week has a significant impact on their comprehensive academic performance, which is reflected in the trend that the more times students eat breakfast, the better their overall academic performance is. Based on this, in order to help students eat breakfast more often, and further improve students’ academic performance, we will strengthen the publicity and education of students’ breakfast knowledge from multiple perspectives.
文摘<strong>Objectives:</strong> The goal was to assess the risk factors for emergency cesarean section versus prophylactic caesarean section. <strong>Materials and Methods:</strong> This was a descriptive analytical cross-sectional study of the Type Cas/Witnesses at the Reference Health Centre of Commune V of the District of Bamako in Mali. The sample consisted of 100 cases for 200 controls (1 case for 2 controls) with retrospective collection of data for the period from January 1 to July 11, 2011 (6 months and 11 days). <strong>Results:</strong> During the study period, out of a total of 3559 deliveries, we recorded 2,794 vaginal deliveries, 78.50% and 765 caesarean sections or 21.50%. Of the 765ceras, we performed 353 emergency caesarean sections or 46.15% and 412 prophylactic caesarean sections 53.85%. We have selected 100 prophylactic caesarean section files and 200 emergency caesarean section files. The average age of the patients was 27.41 years-5.84 with extreme ages of 14 to 40 years. 100% of our patients (Cas) had performed at least one antenatal consultation compared to 83.5% of the parturients evacuated (Witnesses). The most frequently cited reasons for evacuation were: acute fetal suffering, non-cephalic presentation and excessive uterine height with 30%, 17.5% and 12% respectively. The bulk of the caesarean section indications were dominated by dystocies with 90% in cases compared to 65% in Witnesses, followed by acute fetal suffering with 30% in Witnesses. We recorded 30% perinatal deaths among Witnesses compared to 1% in Cases. We recorded 16 uterine ruptures in the Witnesses among which 2 hysterectomies and 14 hystererraphia. <strong>Conclusion:</strong> Prophylactic caesarean section improves maternal and perinatal prognosis more than emergency caesarean section.
文摘The modelling and determination of the geometric parameters of a solar cell are important data, which influence the evaluation of its performance under specific operating conditions, as well as its industrial development for a low cost. In this work, an n+/p/p+ crystalline silicon solar cell is studied under monochromatic illumination in modulation and placed in a constant magnetic field. The minority carriers’ diffusion coefficient (<em>D</em>(<em>ω</em>, <em>B</em>), in the (<em>p</em>) base leads to maximum values (Dmax) at resonance frequencies (<em>ωr</em>). These values are used in expressions of AC minority carriers recombination velocity (Sb(Dmax, H)) in the rear of the base, to extract the optimum thickness while solar cell is subjected to these specific conditions. Optimum thickness modelling relationships, depending respectively on Dmax, <em>ωr</em> and <em>B</em>, are then established, and will be data for industrial development of low-cost solar cells for specific use.
文摘A theory employing the vortex shape of the electron was presented to resolve the enigma of the wave-particle duality. Conventions such as “particle” and “wave” were used to describe the behavior of quantum objects such as electrons. A superfluid vacuum formed the base to describe the basic vortex structure and properties of the electron, whereas various formulations derived from hydrodynamic laws described the electron vortex circumference, radius, angular velocity and angular frequency, angular momentum (spin) and magnetic momentum. A vortex electron fully explained the associations between momentum and wave, and hydrodynamic laws were essential in deriving the energy and angular frequency of the electron. In general, an electron traveling in space possesses internal and external motions. To derive the angular frequency of its internal motion, the Compton wavelength was used to represent the length of one cycle of the internal motion that is equal to the circumference of the electron vortex. The angular frequency of the electron vortex was calculated to obtain the same value according to Planck’s theory. A traveling vortex electron has internal and external motions that create a three-dimensional helix trajectory. The magnitude of the instantaneous velocity of the electron is the resultant of its internal and external velocities, being equal to the internal velocity reduced by the Lorentz factor (whose essence is presented in a detailed formulation). The wavelength of the helix trajectory represents the distance traveled by a particle along its axis during one period of revolution around the axis, resulting in the same de Broglie wavelength that corresponds to the helix pitch of the helix. Mathematical formulations were presented to demonstrate the relation between the energy of the vortex and its angular frequency and de Broglie’s wavelength;furthermore, Compton’s and de Broglie’s wavelengths were also differentiated.
文摘Recently, introduction of renewable energy sources like wind power generation and photovoltaic power generation has been increasing from the viewpoint of environmental problems. However, renewable energy power supplies have unstable output due to the influence of weather conditions such as wind speed variations, which may cause fluctuations of voltage and frequency in the power system. This paper proposes fuzzy PD based virtual inertia control system to decrease frequency fluctuations in power system caused by fluctuating output of renewable energy sources. The proposed new method is based on the coordinated control of HVDC interconnection line and battery, and energy balancing control is also incorporated in it. Finally, it is concluded that the proposed system is very effective for suppressing the frequency fluctuations of the power system due to the large-scale wind power generation and solar power generation and also for keeping the energy balancing in the HVDC transmission line.
文摘Magnetic resonance elastography (MRE) can visualize the shear wave propagation of in vivo tissues, which can be mapped into viscoelastic properties. No study has measured the biomechanical properties of the PM muscle in vivo using MRE. In this study, we evaluated stiffness values calculated by local frequency estimate (LFE) and algebraic inversion of differential equation (AIDE) in PM-MRE. The PM muscles of 17 healthy male volunteers were scanned in supine position by MRE. The Laplacian-based estimate (LBE) phase wrapped image data were filtered by gaussian-bandpass filter (GBF), and by both directional and GBF. LFE (MREWave) and AIDE wave inversion methods were used to calculate the respective elastograms. The wave interferences were removed by directional filtering, and smooth wave fields were obtained. The stiffness values calculated by LFE of non-DF images were 1.39 ± 0.25 kPa and 1.33 ± 0.22 kPa for right and left PM respectively, whereas for DF images, they were 1.26 ± 0.20 kPa for right PM and 1.18 ± 0.28 kPa for left PM. The stiffness values calculated by AIDE of non-DF images were 0.78 ± 0.10 kPa and 0.78 ± 0.13 kPa for right and left PM respectively, whereas for DF images, they were 0.73 ± 0.12 kPa for right PM and 0.74 ± 0.11 kPa for left PM. There was no statistically significant difference in mean values of stiffness with/without applying directional filter whereas there was a statistically significant difference in mean values of stiffness between LFE and AIDE. Both LFE and AIDE could be used for psoas major MR Elastography.
基金supported by the National Natural Science Foundation of China(61503408).
文摘This paper studies the adaptive beamforming algorithm based on the frequency diverse array(FDA)array where the interference is located at the same angle(but different range)with the target.We take the cross subarray-based FDA with sinusoidal frequency offset(CSB sin-FDA)as the receiving array instead of the basic FDA.The sampling covariance matrix under insufficient snapshot can be corrected by the automatic diagonal loading method.On the basis of decomposing the mismatched steering vector error into a vertical component and a parallel one,this paper searches the vertical component of the error by the quadratic constraint method.The numerical simulation verifies that the beamformer based on the CSB sin-FDA can effectively hold the mainlobe at the target position when the snapshot is insufficient or the steering vector is mismatched.
文摘In this study, our goal is to obtain the entanglement dynamics of trapped three-level ion interaction two laser beams in beyond Lamb-Dicke parameters. Three values of LDP, <span style="white-space:nowrap;"><em>η</em>=0.09, <span style="white-space:nowrap;"><em>η</em>=0.2 </span></span>and <span style="white-space:nowrap;"><em>η</em>=0.3 </span>are given. We used the concurrence and the negativity to measure the amount of quantum entanglement created in the system. The interacting trapped ion led to the formation of phonons as a result of the coupling. In two quantum systems (ion-phonons), analytical formulas describing both these measurements are constructed. These formulas and probability coefficients include first order terms of final state vector. We report that long survival time of entanglement can be provided with two quantum measures. Negativity and concurrence maximum values are obtained N = 0.553 and for LDP = 0.3. As a similar, the other two values of LDP are determined and taken into account throughout this paper. For a more detailed understanding of entanglement measurement results, “contour plot” was preferred in Mathematica 8.
基金the National Natural Science Foundation of China(No.11335014).
文摘A 1.5 GHz passive third harmonic superconducting cavity was proposed to improve the beam quality and lifetime in the Shanghai Synchrotron Radiation Facility Phase-II beamline project.Lifetime improvement highly depends on the resonant frequency of the passive third harmonic superconducting cavity.It is important that the operating frequency of the cavity is within the design range and the cavity has reasonable mechanical stability.A simulation method for the multiphysics coupled analysis has been developed based on the ANSYS code.Multiphysics coupled simulations have been performed under different conditions,such as etching,evacuation,cooling,and preloading.Analyses of mechanical modes and structural stress have been executed.A possible stiffening ring method for the two-cell superconducting niobium cavity has been investigated.In this paper,we present a multiphysics coupled analysis of the third harmonic cavity using a finite element analysis code.The results of the analysis show that a reliable frequency for the cavity after electron beam welding is 1498.033 MHz,and the corresponding frequency of the pre-tuning goal is 1496.163 MHz.A naked cavity is a reasonable option based on structural stress and mechanical modal analyses.A frequency range of±500 kHz and limiting tolerable displacement of±0.35 mm are proposed for the design of the frequency tuner.
文摘In order to improve the electrical and frequency characteristics of SiGe heterojunction bipolar transistors (HBTs), a novel structure of SOI SiGe heterojunction bipolar transistor is designed in this work. Compared with traditional SOI SiGe HBT, the proposed device structure has smaller window widths of emitter and collector areas. Under the act of additional uniaxial stress induced by Si0.85Ge0.15, all the collector region, base region and emitter region are strained, which is beneficial to improve the performance of SiGe HBTs. Employing the SILVACOⓇTCAD tools, the numerical simulation results show that the maximum current gain βmax, the Earley voltage VA are achieved for 1062 and 186 V, respectively, the product of β and VA, i.e., β ×VA, is 1.975 × 105 V and, the peak cutoff frequency fT is 419 GHz when the Ge component in the base has configured to be a trapezoidal distribution. The proposed SOI SiGe HBT architecture has a 52.9% improvement in cutoff frequency fT compared to the conventional SOI SiGe HBTs.
文摘The discovery of a data based informational wave pattern infuses coherent entanglement into the system. This discovery of how to add coherent entanglement into the model provides the missing key, that has opened the door to understanding the universe. It is found that the inclusion of coherence and entanglement at the start of the system is extremely simple and in fact it is so simple that it has simply been overlooked. Entanglement and coherence are the most fundamental aspects of our universe. It is demonstrated that the basic model of the hydrogen atom is made from the CMB. If we add entanglement into this basic model of the hydrogen atom a math system called Wave Pattern Entangled Math is unveiled. This system of wave interference mathematics creates a data system in which entanglement and coherence can easily be understood. The final outcome is an unbreakable pattern of information, including entangled energy, entropy, spin, universal expansion, compression, velocity of light, C2, and Quantum Coherence.
基金The third author acknowledges the financial support from the Scientific and Technological Research Council of Turkey(TUBITAK),Project ID:218 M372.
文摘Despite their high manufacturing cost and structural deficiencies especially in tip regions,highly skewed propellers are preferred in the marine industry,where underwater noise is a significant design criterion.However,hydrodynamic performances should also be considered before a decision to use these propellers is made.This study investigates the trade-off between hydrodynamic and hydroacoustic performances by comparing conventional and highly skewed Seiun Maru marine propellers for a noncavitating case.Many papers in the literature focus solely on hydroacoustic calculations for the open-water case.However,propulsive characteristics are significantly different when propeller-hull interactions take place.Changes in propulsion performance also reflect on the hydroacoustic performances of the propeller.In this study,propeller-hull interactions were considered to calculate the noise spectra.Rather than solving the full case,which is computationally demanding,an indirect approach was adopted;axial velocities from the nominal ship wake were introduced as the inlet condition of the numerical approach.A hybrid method based on the acoustic analogy was used in coupling computational fluid dynamics techniques with acoustic propagation methods,implementing the Ffowcs Williams-Hawkings(FW-H)equation.The hydrodynamic performances of both propellers were presented as a preliminary study.Propeller-hull interactions were included in calculations after observing good accordance between our results,experiments,and quasi-continuous method for the open-water case.With the use of the time-dependent flow field data of the propeller behind a nonuniform ship wake as an input,simulation results were used to solve the FW-H equation to extract acoustic pressure and sound pressure levels for several hydrophones located in the near field.Noise spectra results confirm that the highest values of the sound pressure levels are in the low-frequency range and the first harmonics calculated by the present method are in good accordance with the theor
文摘From resolution of two-dimensional equation of heat in dynamic frequency regime, we have plotted evolution curves of temperature according to depth of material or in lateral direction. They will allow us to evaluate thermal behavior of towed material. Aim of study is to use fibers as a thermal insulating material by proposing a method for determining effective thermal insulation layer in dynamic frequency regime.