概率难点分析

概率一直是近几年高考热点,由于没有排列组合知识作为基础,学生学习起来有一定困难,下面就概率几个方面的问题作一下分析:难点一古典概型中基本事件的等可能性问题对于古典概型来说,关键点就是要求基本事件的等可能性。

A new approach of extracting vegetation points from urban airborne LiDAR data

Urban vegetation has been an important indicator for the evaluation of eco-cities, which is of great significance to promote eeo-city construction. We study and discuss the commonly used urban vegetation extrac-tion methods. The extraction of vegetation points in this study is completed through mathematical statistics, mean-square error, successive differences and iterative algorithm which are based on the analysis of different spatial morphological characteristics in urban point clouds. Linyi, a city of Shandong Province in China, is se-lected as the study area to test this method and the result shows that the proposed method has a strong practicali- ty in urban vegetation point cloud extraction. Only 3D coordinate properties of the LiDAR point clouds are used in this method and it does not require additional information, for instance, return intensity, which makes the method more applicable and operable.

A NEW SINGULARITY EXTRACTION TECHNIQUE FOR TDEFIE

A new singularity extraction technique is presented to calculate accurately the singular integrals in Time Domain Electric Field Integral Equation (TDEFIE).In singularity extraction pro- cedure,through the aid of the first order Taylor series of time base function including time-retardation,the singularity of the integrand can be removed.The surface current density and backscattered far-field response of a conducting cube illuminated by a Gaussian plane wave is com- puted using the presented technique.Comparisons are made with the results obtained by the Inverse Discrete Fourier Transform (IDFT) of the frequency domain and the results obtained by using Ve- chinski's time averaging technique,which demonstrate that the presented method with this new time domain singularity extraction technique to solve TDEFIE is very accurate and stable.

Vaccum Extraction-Maternal and Neonatal Complications

The purpose of this research was to evaluate the complications for the mother and newborn, using vacuum extraction, and to compare them with spontaneous delivery. This study included group of vacuum-assisted deliveries in time period 2014-2016 （n = 726） in Riga Maternity Hospital, and it was compared to the group of spontaneous vaginal deliveries （n = 726）. Data statistically processed in Microsoft Excel mid SPSS Statistics 22.0. Results of the study： in vacuum-assisted deliveries vaginal lacerations was 13.8% more, cervical lacerations was 9.8% more than in group of spontaneous vaginal deliveries, perineal lacerations were 25.6% less in group with vacuum extraction, neonatal cephalohematomas was 26.9% more, and clavicle factures was 3.3% more in vacuum-assisted deliveries. Vacuum extraction was used for the first delivery in 86.9% of cases, for the second delivery 10,9% of cases. Vacuum-assisted deliveries in comparison with spontaneous vaginal deliveries are associated with higher risks for maternal soft tissue ruptures and neonatal cephalohematomas, clavicle factures. It is important to evaluate the indications for use of vacuum extractor. Staff skills, using vacuum extraction method, should be at a high level.

Ethanol Extraction of Hyoscyamus niger and Hypericum calycinum Evaluated for Acaricidal Activity against Tetranychus urticae Koch （Acari： Tetranychidae）

Hyoscyamus niger L. （Solanaceae） and Hypericum calycinum L. （Hypericaceae） were collected from two provinces Bursa and Ankara in Turkey during flowering stages. Extracts obtained from H. niger and H. calycinum were tested against two-spotted mite as an acaricidal pesticide. Bioassay experiments were carried out under laboratory conditions using two different methods namely, leaf disc dipping and direct leaf spraying. Two-spotted mite was reared in insectary using Phaseolus vulgaris L. （Fabaceae）. In the leaf dipping method, H. niger extract resulted in an effective adjusted mortality for larvae of 87.13% and for adults of 81.66%. For H. calycinum the adjusted mortality for larvae and adults was 77.77% and 85.97% respectively at the highest concentration. In larval stage, LCs0 values were 5.47 w/v and 3.32 w/v dipping and spraying method respectively. In addition, adult stage, it was determined that LCs0 values were 1.17 w/v and 3.56 w/v in both methods. For leaf spraying method. H. niger resulted in an adjusted showed an effect against larvae and adults mortality rate was 95% and 91% respectively. However, H. calycinum mortality percentage was 80% and 87% at 12% concentration, with LC50 values of 9.62 w/v and 2.13 w/v in dipping method. In this research apart from mortality effects on egg, reproduction was also investigated. Each concentration showed that treated females laid less eggs compared to the untreated females.

Adaptive TQWT filter based feature extraction method and its application to detection of repetitive transients

The local defect in rotating machine always gives rise to repetitive transients in the collected vibration signal. However, the transient signature is prone to be contaminated by strong background noises, thus it is a challenging task to detect the weak transients for machine fault diagnosis. In this paper, a novel adaptive tunable Q-factor wavelet transform(TQWT) filter based feature extraction method is proposed to detect repetitive transients. The emerging TQWT possesses distinct advantages over the classical constant-Q wavelet transforms, whose Q-factor can be tuned to match the oscillatory behavior of different signals, but the parameter selection for TQWT heavily relies on prior knowledge. Within our adaptive TQWT filter algorithm, the automatic optimization techniques for three TQWT parameters are implemented to achieve an optimal TQWT basis that matches the transient components. Specifically, the decomposition level is selected according to a center frequency ratio based stopping criterion, and the Q-factor and redundancy are optimized based on the minimum energy-weighted normalized wavelet entropy.Then, the adaptive TQWT decomposition can be achieved in a sparse way and result in subband signals at various wavelet scales.Further, the optimum subband signal which carries transient feature information, is identified using a normalized energy to bandwidth ratio index. Finally, the single branch reconstruction signal from the optimum subband is obtained with transient signatures via inverse TQWT, and the frequency of repetitive transients is detected using Hilbert envelope demodulation. It has been verified via numerical simulation that the proposed adaptive TQWT filter based feature extraction method can adaptively select TQWT parameters and the optimum subband for repetitive transient detection without prior knowledge. The proposed method is also applied to faulty bearing vibration signals and its effectiveness is validated.

Depth extraction method with high accuracy in integral imaging based on moving array lenslet technique

In order to improve depth extraction accuracy, a method using moving array lenslet technique(MALT) in pickup stage is proposed, which can decrease the depth interval caused by pixelation. In this method, the lenslet array is moved along the horizontal and vertical directions simultaneously for N times in a pitch to get N sets of elemental images. Computational integral imaging reconstruction method for MALT is taken to obtain the slice images of the 3 D scene, and the sum modulus(SMD) blur metric is taken on these slice images to achieve the depth information of the 3 D scene. Simulation and optical experiments are carried out to verify the feasibility of this method.

A novel fusion method of improved adaptive LTP and two-directional two-dimensional PCA for face feature extraction

In this paper, under different illuminations and random noises, focusing on the local texture feature's defects of a face image that cannot be completely described because the threshold of local ternary pattern(LTP) cannot be calculated adaptively, a local three-value model of improved adaptive local ternary pattern(IALTP) is proposed. Firstly, the difference function between the center pixel and the neighborhood pixel weight is established to obtain the statistical characteristics of the central pixel and the neighborhood pixel. Secondly, the adaptively gradient descent iterative function is established to calculate the difference coefficient which is defined to be the threshold of the IALTP operator. Finally, the mean and standard deviation of the pixel weight of the local region are used as the coding mode of IALTP. In order to reflect the overall properties of the face and reduce the dimension of features, the two-directional two-dimensional PCA((2D)~2 PCA) is adopted. The IALTP is used to extract local texture features of eyes and mouth area. After combining the global features and local features, the fusion features(IALTP+) are obtained. The experimental results on the Extended Yale B and AR standard face databases indicate that under different illuminations and random noises, the algorithm proposed in this paper is more robust than others, and the feature's dimension is smaller. The shortest running time reaches 0.329 6 s, and the highest recognition rate reaches 97.39%.