基于KL散度的DCT系数分布模型研究

利用分布拟合优度检验方法,对DCT系数分布模型进行了研究。通过理论分析和实验,验证了KL散度更适合作为DCT系数分布拟合优度度量;针对单个位置和不同范围的DCT系数,系统地比较了当前应用最广泛的4种DCT系数分布模型。实验结果表明,图像中低频交流系数服从对称α稳态分布而高频交流系数服从广义高斯分布。

Analysis on Differences in Photosynthetic Characteristics of Korla Fragrant Pear among Different Planting Densities

[Objective] The aim of this study was to explore the differences in photosynthetic characteristics of Korla fragrant pear among different planting densities,providing a basis for the improvement of fruit yield and quality of Korla fragrant pear in production. [Method] The net photosynthetic rates, photoresponse curves and CO2 response curves of Korla fragrant pear under six different planting densities were determined using Li-6400 XT portable photosynthesis system. [Result] There were significant differences in photosynthetic parameters of Korla fragrant pear among six different planting densities. The net photosynthetic rate of Korla fragrant pear was highest under the planting density of 4.0 m × 6.0 m. At the planting density of4.0 m×6.0 m, when the light intensity reached 1 800 μmol/（m^2·s）, the net photosynthetic rate of Korla fragrant pear reached the peak [19.326 μmol/（m^2·s）], and the apparent quantum yield, carboxylation efficiency and dark respiration rate all reached the maximum values; at the planting density of 6.0 m ×7.0 m, Korla fragrant pear showed lower light compensation point and CO2 compensation point, but higher light saturation point. At the planting density of 3.0 m ×5.0 m, Korla fragrant pear had higher light saturation point. [Conclusion] Among the six different planting densities,Korla fragrant pear with planting density of 4.0 m ×6.0 m showed the highest net photosynthetic rate. It suggested that Korla fragrant pear, at the planting density of4.0 m ×6.0 m, had stronger utilization capacity for low light and low-concentration CO2. Therefore, the Korla fragrant pear with the planting density of 4.0 m ×6.0 m has the highest photosynthesis efficiency, and the planting density of 4.0 m ×6.0 m is the most ideal planting density for Korla fragrant pear.

德国冰酒迎来绝佳年份

2016年1月18日,德国葡萄酒协会确认2015年份冰酒采收季正式开始。几乎所有的德国葡萄酒法定产区均具备采收冰酒的条件,采收的品种主要有雷司令、西万尼、黑皮诺。德国冰酒因其纯净的果味、富裕的香气、优雅紧实的酸度及甜美如蜜的口感深受广大葡萄酒爱好者们的喜爱。

爱的流刑地 熟男熟女的究级纯爱

影片名:《爱的流刑地》导演/编剧:鹤桥康夫主演:丰川悦司(饰村尾菊治)寺岛忍(饰入江冬香)长谷川京子(饰织部美雪)地区:日本类型:剧情片长:125分钟情节介绍:如果是真的爱我,就杀了我。"如果你真的爱我,就杀了我。"盛夏的清晨,在东京某高级公寓内,男子轻轻地将双手扣上女子的脖子,猛然用力,女子渐渐气绝。男子前往警察局自首。

Experimental Investigation of Single-phase Flow in Structured Packing by LDV

To date, many models have been developed to calculate the flow field in the structured packing by the computational fluid dynamics （CFD） technique, but little experimental work has been carried out to serve the vali-dation of flow simulation. In this work, the velocity profiles of single-phase flow in structured packing are measured at the Reynolds numbers of 20.0, 55.7 and 520.1, using the laser Doppler velocimetry （LDV）. The time-averaged and instantaneous velocities of three components are obtained simultaneously. The CFD simulation is also carried out to numerically predict the velocity distribution within the structured packing. Comparison shows that the flow pattern, velocity distribution and turbulent kinetic energy （for turbulent flow） on the horizontal plane predicted by CFD simulation are in good agreement with the LDV measured data. The values of the x-and z-velocity components are quantitatively well predicted over the plane in the center of the packing, but the predicted y-component is sig-nificantly smaller than the experimental data. It can be concluded that experimental measurement is important for further improvement of CFD model.

Error Analysis and Accuracy Assessment of GPS Absolute Velocity Determination without SA

Error sources which decrease the accuracy of GPS in absolute velocity determination have been changed since SA was turned off. Firstly, quantities of all kinds of error sources that influence velocity deter-mination are analyzed. The potential accuracy of GPS absolute velocity determination is derived from both theory and field GPS data simulation. After that, two tests were carried out to evaluate the performance of GPS absolute velocity determination in the case of a static and an airborne GPS receiver and INS (Inertial Navigation System) instrument in kinematic mode. In static mode, the receiver velocity has been estimated to be several mm/s with the carrier-phase derived Doppler measurements, and several cm/s with the receiver generated Doppler measurements. In kinematic mode, GPS absolute velocity estimates are compared with the synchronized measurements from the high accuracy INS. The root mean square statistics of the velocity discrepancies between GPS and INS come up to dm/s. Moreover, it has a strong correlation with the accel-eration or jerk of the aircraft.

Estimation of suspended sediment concentrations using Pulse-coherent Acoustic Doppler Profiler (PCADP)

The objective of the study is to investigate the suitability of using Pulse-coherent Acoustic Doppler Profiler (PCADP) to estimate suspended sediment concentration (SSC). The acoustic backscatter intensity was corrected for spreading and absorption loss, then calibrated with OBS and finally converted to SSC. The results show that there is a good correlation between SSC and backscatter intensity with R value of 0.74. The mean relative error is 22.4%. Then the time span of little particle size variation was also analyzed to exclude the influence of size variation. The correlation coefficient increased to 0.81 and the error decreased to 18.9%. Our results suggest that the PCADP can meet the requirement of other professional instruments to estimate SSC with the errors between 20% and 50%, and can satisfy the need of dynamics study of suspended particles.

Q estimation using multifrequency point average method based on the Taylor series expansion with a different order

The quality factor Q is an important parameter because it can refl ect the reservoir attenuated features and can be used for inverse-Q filtering to compensate for the seismic wave energy.The accuracy of the Q estimation is greatly significant for improving the precision of the reservoir prediction and the resolution of seismic data.In this paper,the Q estimation formulas of the single-frequency point are derived on the basis of a diff erent-order Taylor series expansion of the amplitude attenuated factor.Moreover,the multifrequency point average(MFPA)method is introduced to obtain a stable Q estimation.The model tests demonstrate that the MFPA method is less aff ected by the frequency band,travel time diff erence,time window width,and noise interference than the logical spectrum ratio(LSR)method and the energy ratio(ER)method and has a higher Q estimation accuracy.In addition,the proposed method can be applied to post-stack seismic data and obtain eff ective Q values of complex models.When the MFPA method was applied to real marine seismic data,the Q values estimated by the MFPA method with the 1st–4th order showed good consistency with each other.In contrast,the Q values obtained by the ER method were larger than those of the proposed method,while those estimated by the LSR method signifi cantly deviated from the average values.In conclusion,the MFPA method has superior stability and practicability for the Q estimation.

Computations on the Earth Terrain Return of Pulse Doppler Radar Altimeter

Concerning the PDRA (pulse doppler radar altimeter) designing and evaluation, owing to that the specifications of PDRA should be adaptively fixed according to the ETR (earth terrain return), and that in certain stages of product evaluation of PDRA which means the designations of PDRA are successful or not, the usage of ETR are indispensable, so the terrain return from spherical earth is critically important. A complete analytic derivation of the antenna shot section model of PDRA and the bright section model constrained by pulse emitted from antenna are given. Furthermore, the doppler effect mode and the earth terrain RCF (radar crossing factor) model are constructively analyzed. Then, the computing methodology on PDRA, which are used to compute the scattering power, scattering doppler spectrum, and the scattering signal, is studied. Besides, in order to check the correctness and efficiency of the algorithm, computing examples of ETR (earth terrain return) under the supposing premises are furnished. Finally, the conclusion is drawn that the models and algorithm are rational, the computational precise is satisfactory, the cost of computing time is low.

High-Sensitivity Acquisition of Ultrahigh Dynamic Direct Sequence Spread Spectrum Signals in Space Communications

According to the requirements of the high-sensitivity acquisition of Direct Sequence Spread Spectrum(DSSS) signals under ultrahigh dynamic environments in space communications, a three-dimensional joint search of the phase of Pseudo-Noise-code(PN-code),Doppler frequency and its rate-of-change is presented to achieve high sensitivity in sensing high-frequency dynamics. By eliminating the correlation peak loss caused by ultrahigh Doppler frequency and its rate-of-change offset,the proposed method improves the acquisition sensitivity by increasing the non-coherent accumulation time. The validity of the algorithm is proved by theoretical analysis and simulation results. It is shown that signals with a carrier- to-noise ratio as low as 39 dBHz can be captured with high performance when the Doppler frequency is up to ±1 MHz and its rate-of-change is up to ±200 kHz/s.

APPROACH OF IMPROVING PRECISION IN ULTRASONIC DOPPLER BLOODSTREAM SPEED MEASUREMENT BY CHAOS-BASED FREQUENCY DETECTING

It is critical for cerebral vascular disease diagnosis through Doppler to detect the maximum and the minimum of the carotid blood flow speed accurately. A kind of Duffing system under an external periodic power with dump is introduced in the letter, numerical analysis is carried out by four-order Runge-Kutta method. An oscillator array is designed according to the frequency of the ultrasonic wave. When the external signals are inputted, computational algorithm is used to scan the array in turn and analyze the result, and the frequency can be determined. Based on the methods above, detecting the carotid blood flow speed accurately is realized. The Signal-to-Noise Ratio (SNR) of-20.23dB is obtained by the result of experiments. In conclusion, the SNR has been improved and the precision of the measured bloodstream speed has been increased, which can be 0.069% to 0.13%.

A Modified Doppler Frequency Trajectory Undergoing Varying Velocities in HSR Communications

The varying trajectory of Doppler frequency under changing speed motion conditionsare investigated in Highspeed Railway(HSR) scenarios.Based on the geometrical physical parameters,instantaneous Doppler trajectories and expression forms of the change rate arededuced,including acceleration and deceleration cases.These modified models provide more accurate and realisticapproximations in modeling rapidly fading channels.

Application of Fiber in Blood Speed Measurement

There exist many methods to measure blood speed, all of which have some serious shortcomings. As fiber is characterized by tiny diameter, and low lost ratio of power and flexibility, it is suitable for measuring blood speed. It is proved that the speedometer has high space resolving power,high time resolving power, and outstanding capability of approaching target, etc.

High-Order Radial Derivatives of Harmonic Function and Gravity Anomaly

The first through ninth radial derivatives of a harmonic function and gravity anomaly are derived in this paper. These derivatives can be used in the analytical continuation application. For the downward continuation of gravity anomaly, the Taylor series approach developed in the paper is equivalent theoretically to but more efficient and storage-saving computationally than the well-known gradient operator approach. Numerical simulation shows that Taylor series expansion constructed by the derived formulas for the radial derivatives of gravity disturbance is still convergent for height up to 4 km.

Characteristics of nonlinear internal waves observed in the northern South China Sea

The South China Sea(SCS) is one of the most active areas of internal waves.We undertook a program of physical oceanography in the northern South China Sea from June to July of 2009,and conducted a 1-day observation from 15:40 of June 24 to 16:40 of June 25 using a chain of instruments,including temperature sensors,pressure sensors and temperature-pressure meters at a site(117.5°E,21°N) northeast of the Dongsha Islands.We measured fluctuating tidal and subtidal properties with the thermistor-chain and a ship-mounted Acoustic Doppler Current Profiler,and observed a large-amplitude nonlinear internal wave passing the site followed by a number of small ones.To further investigate this phenomenon,we collected the tidal constituents from the TPXO7.1 dataset to evaluate the tidal characteristics at and around the recording site,from which we knew that the amplitude of the nonlinear internal wave was about 120 m and the period about 20 min.The horizontal and vertical velocities induced by the soliton were approximately 2 m/s and 0.5 m/s,respectively.This soliton occurred 2-3 days after a spring tide.

Metric Expansion from Microscopic Dynamics in an Inhomogeneous Universe

Theories with ingredients like the Higgs mechanism, gravitons, and inflaton fields rejuvenate the idea that relativistic kinematics is dynamically emergent. Eternal inflation treats the Hubble constant H as depending on location. Microscopic dynamics implies that H is over much smaller lengths than pocket universes to be understood as a local space reproduction rate. We illustrate this via discussing that even exponential inflation in TeV-gravity is slow on the relevant time scale. In our on small scales inhomogeneous cosmos, a reproduction rate H depends on position. We therefore discuss Einstein-Strauss vacuoles and a Lindquist-Wheeler like lattice to connect the local rate properly with the scaling of an expanding cosmos. Consistency allows H to locally depend on Weyl curvature similar to vacuum polarization. We derive a proportionality constant known from Kepler＇s third law and discuss the implications for the finiteness of the cosmological constant.

Nonlinear Dynamics of Rayleigh Taylor Instabilities Studied with a Lattice Boltzmann Method

Multi-relaxation time lattice Boltzmann method is employed to study the later stages of Rayleigh Taylor instabilities. A heavy fluid is placed over an immiscible lighter fluid in an unstable equilibrium. Various initial disturbances are used to initiate the flow. The D2Q9 lattice arrangement is employed on the computational domain. The density distribution function is determined for both fluids, and a coloring function is used to highlight the two fluids. Interactive forces and body forces are modelled by using the Shah and Chert model. Three different initial disturbances are studied, and their late stages are examined. The classic mushroom structure can be seen on all three cases. Distortions of the mushroom structures are seen due to the effects of the boundary and the influence of the initial disturbance.

Electronic Response of Nano-sized Cages of ZnO and MgO to Presence of Nitric Oxide

We have performed a comparative theoretical study on the adsorption of nitric oxide （NO） on Zn12012 and Mgt2012 nanocages in terms of their energetic, geometric, and electronic properties. It has been found that NO adsorption on the MgO nanocage is energetically more favorable than that on the ZnO one. In contrast to the ZnO nanocage, HOMO-LUMO energy gap （Eg） of MgO one is dramatically decreased in the presence of NO molecule so that it is transformed from an intrinsic semiconductor （Eg≈5.00 eV） to a p-type one （Eg≈1.93 eV）. We have predicted that electronic and conductance properties of the Mg12012 nanocage are sensitive toward NO molecule, thus it may be potential candidate in detection of NO molecules.

Harmonic Bergman Metric

We have constructed the positive definite metric matrixes for the bounded domains of R^n and proved an inequality which is about the Jacobi matrix of a harmonic mapping on a bounded domain of R^n and the metric matrix of the same bounded domain.

Experimental Investigation of Spray Evaporation in Turbulent Flow in Countercurrent Humidifier

The process in the countercurrent humidifier of HAT cycle involves the evaporation of atomized liquids in a turbulent environment. To allow an optimization of such process and provide data for the validation of numerical calculation, the spray evaporation in a countercurrent air stream was studied experimentally. Measurements were taken for different flow parameters, such as airflow rate and liquid flow rate in order to provide reliable data. Phase-Doppler anemometry (PDA) was applied to obtain the spatial change of the droplet size spectrum in the flow field and to measure droplet size-velocity correlations. These local measured profiles of droplet mean velocities, velocity fluctuations and droplet mean diameters were obtained by averaging over all droplet size classes. Moreover, DualPDA signal processing allows accurate determination of the droplet mass flux and local concentration, from which the global evaporation rates could also be determined. These local temperature profiles were measured using the thermocouple and acquired by data acquisition system based on virtual instrument (VI) technology.