A novel substrate integrated waveguide broadband bandpass filter

A novel broadband substrate integrated waveguide bandpass filter is presented based on the highpass characteristics of substrate integrated waveguide (SIW) and the bandstop performance of photonic band gap (PBG) structure.In order to verify it,a wideband bandpass filter with center frequency of 5.0 GHz and fractional bandwidth of 60% is designed.The electromagnetic simulation results show its good passband characteristics from 3.5 GHz to 6.5 GHz,and the maximun insertion loss is about 0.64 dB.An experimental filter prototype is fabricated with standard PCB technics and measured with the vector network analyzer.The measured results show the passband is from 3.8 GHz to 6.8 GHz,the fractional bandwidth is about 56%,and the minimal insertion loss is about 1.6 dB.The measured results are in good agreement with the simulated results.     

The application research on improvement of constant sinusoidal signal sampling precision based on adaptive filter

A novel scheme is present to improve the conversion accuracy of ADC. The proposed approach uses adaptive sinusoidal filter. For the measurement of the signal with given frequency, the automatic adjustment of filter coefficients is based on least mean-square error rule, which is a mathematical tool can be employed to make filter output signal achieve the best approximation to the needed one. Then based on the result, it is able to get the amplitude and phase of the measured signal accurately. MATLAB software is used to verify the effectiveness of the algorithm. It proves that adaptive filter has improved the accuracy and signal-to-noise ratio of ADC, which is equal to increase the conversion digits.     

Functional source separation to finger tappingrelated magnetoencephalography signal

It has been verified that the ICA can isolate sources from multi channel magnetoencephalography (MEG) signals. Based on the route of constrained ICA (cICA), this paper achieves a new solution of MEG inverse problem called functional source separation (FSS) by adding a functional constraint to the cost function of a basic ICA model. Source activity is obtained by applying this method to one MEG signal dataset under a self paced finger tapping task. The result is proved effective by calculating correlation coefficients between the weight vectors of function source separation method and the spatial filter coefficients of SAM method. It is found that finger tapping related functional source was localized in motor cortex of precentral gyrus. At the same time, the temporal and frequency information provided by FSS method could be a basis of exploring cortical control timing mechanisms associated with finger movements and extracting time frequency characteristics of the functional source.     

The Application of Narrowband Interference Suppression in Direct Sequence Spread Spectrum

In order to improve the system effect, it is necessary take the technique of digital signal process to suppress interference, because of the finite gain and the narrow-band interference in system of direct sequence spread spectrum. The authors design a new filter structure improving on tunable digital heterodyne adaptive notch filters. This filter can adaptively track the interference frequency and control the bandwidth and depth of notch, which has the excellent agility and utility. The experiment proves this method overcomes limitation of other interference suppressions, hardly weaken the system performances, enhances the stability of the filter system, and can quickly track the interference frequency.     

THE RESEARCH OF MONITORING AND DIAGNOSING BALL BEARING FATIQUE ON LINE

This paper describes the research work of analyzing vibration signal to monitor and diagnose on line the ball bearing fatique. Carrying out a large mumber of life test on ball bearing test machine, it is discovered that in the so called "second effect" vibration signal as the bearing fatique occurs, apart from the two widely used spetrum charactersof "fraverse frequency" and "high frequency shock pulse" , there is another important but rarely known opcctrum characteristic of high frequency peaks existing in the middle-to-high frequency band.The generating mechanism, effect factors and test method of those high frequency peaks are researched tentativ tentatively. Two binds of device for monitoring abnd diagnos sing ball learing fatique on line are developed based ion this new type spectrum characteristic. One consists of a bandpass filter, the other is based on the spetrum characters which corns from the DDS ( Dynamic Data System ) modeling     

LCL型CPT系统的参数设计方法及频率特性分析

以金鲳鱼为原料,固定小麦粉与水的质量比为2∶1,食盐添加量2%,微波真空度0.095 MPa,在单因素试验的基础上,通过正交试验对微波真空技术膨化鱼糜饼工艺条件进行优化。结果表明,鱼糜饼制作的最佳工艺条件为:鱼糜含量35%,膨化温度100℃,膨化时间20 min,鱼糜饼厚度2 mm,在该工艺条件下,制得的膨化鱼糜饼色泽金黄、质地酥脆、风味清香,成品膨化率可达到540%。     

宰后牛骨骼肌肉生物电阻抗特性初探

用四电极法在多频(5-200kHz)条件下对宰后牛骨骼肌肉的电阻抗特性进行了初步的研究。发现牛骨骼肌生物电阻抗与肌肉纤维方向、电流信号频率和宰后肌肉所经历的阶段有关。横向电阻(沿垂直于骨骼肌纤维方向)大于纵向电阻(沿骨骼肌纤维方向),而且受电流信号频率的影响较明显,尤其是在5￣100kHz范围内。牛宰后生物电阻抗的变化与pH值的变化有一定的相关性。     

High speed, high precision digital phase sensitive detector design for electrical impedance tomography

Electrical impedance tomography (EIT) system must have the properties of high precision and speed, thus the digital phase sensitive detector (DPSD) based on the field programmable gate array(FPGA) is developed for data collection of EIT. Based on the principle of DPSD, the relationship between signal to noise ratio (SNR) and sample resolution as well as total number of samples is deduced. An implementation scheme of this system and a method of designing analog to digital converter (ADC) clock based on direct digital synthesis (DDS) technology are provided. The system adopts high speed multi channel ADC and low jitter clock conditioner for ADC. Real time DPSD is implemented with FPGA. The experiments show that the measurement accuracy reaches 0.03% and the SNR reaches 85 dB. The agar phantom experiments prove that the performance of the DPSD meet the designing requirement for EIT.     

Nonlinear Response of Cable with Small Sag under Narrow Band Random Excitation

Nonlinear planar response of a cable under plannar narrow band radom excitation is studied.A response equation for the mean square deflection is obtained under a single mode approximation by using the equivalent linearization technique.It is shown that the response is triple valued,if the center frequency of excitation lies in a certain specified range.The triple valued response occure only if the excitation of excitation lies in a certain specified range.The triple valued response occures only if the excitation bandwidth is smaller than a critical value which is monotonically increasing function of the intensity of excitation.     

Design and Realization of Circular Polarization Microstrip Antenna

The circular polarization microstrip antenna is one kind of low cut plane antenna element . Researching circular polarization microstrip antenna property is very important in antenna design. And how to find the feed place is the key to design. Researching makes a detailedly analysing and expounding of the pentagon circular polarization microstrip antenna in view of the single ended side. The microstrip antenna realization means is introduced. The way to analyze polygon microstrip antennal is given, which is named finite cell. By adjusting the 5.6 GHz pentagon circular polarization microstrip antenna, we give out the circular polarization microstrip antenna design processing. The feed place is found with the right means. Adopting HFSS software to optimize the design , and carries on imitation , give out the right imitation result .     

EEG Signal Denoising Based on Wavelet Transform

The article focuses on the method of noise cancellation for EEG signal. The method of notch filter is discussed. According to the frequency of noise and the principle of notch filter, the design result of the notch filter and the denoised signal are presented. Then, the analysis of EEG signal are proposed based on wavelet transform (WT) and noise cancellation using WT. Wavelet transform is a multi-resolution time-frequency analysis method. It can decompose mixed signal into signals at different frequency bands. The EEG signal is analyzed and denoised using WT, then the results are presented respectively. Comparing the experiment results shows that WT can detect and process noise in the EEG signal effectively.     

A dual-boost three-phase DC link active power filter based on coupled impedance

A three-phase DC link active power filter (APF)based on coupled impedance and its control strategy are proposed in order to eliminate the input current harmonics of the three-phase diode rectifier. The presented APF is composed of impedance network and two asymmetric dual Boost converters. Average current control is adopted to control the DC link APF. The switch signals of the two asymmetric Boost converters are obtained respectively by leading and trailing edge modulation methods. Compared with the normal DC link active power filter,this topology reduces an active switch and a capacitance. So it can reduce costs,and there is no voltage imbalance in the DC link. Simulation results verify the correctness of the proposed topology and the corresponding control method.     

频域滤波的水泥路面图像降噪增强方法

针对在水泥路面裂缝图像识别中刻槽和纵向条带状形成的噪声干扰,提出了一种基于频域滤波的降噪增强方法。首先,分析了这两类噪声的频谱特征,并根据空域图像中刻槽的周期性,推导了频域图像中刻槽谱峰的位置,设计了消除这些谱峰的系列滤波器。根据纵向条带状干扰属于低频成分的特性,设计了抑制低频、增强高频的滤波器,经优化滤波器参数达到消除这类干扰的效果。实验结果表明,该方法能够消除两类噪声干扰,同时,增强了裂缝的对比度,为水泥路面裂缝识别提供了理论基础。     

Frequency domain analysis and the application for extracting electroencephalogram signal characteristic waves

A new quantitative analysis method to describe the dynamic variation of electroencephalogram (EEG) signals was proposed. Based on the Fourier transformation, the method is called Fourier multi resolution analysis (FMRA). FMRA decomposes the frequency domain with a binary system and can resolve EEG signals into the basic rhythms of the four waves to study the dynamic characteristics of EEG signal rhythms. FMRA has clear physical meaning, and can obtain more information than wavelet multi resolution analysis does. FMRA can extract perfectly the rhythmic characteristics of EEG signals in the time and frequency domains.     

A NEW FREQUENCY SYNTHESIS METHOD

A new frequency synthesis method is presented in this paper. Its fundamental ideology is that for any frequency needed to be output,the controller sends a different group of dividing numbers to the feedback programmable divider of PLL by means of a special algorithm so as to make the interference frequency at the output of the phase detector and the frequency resolution indeqendent from each other. Therefore,high resolution and wide bandwidth are achieved simultaneously.     

Fast modeling of the motor broadband equivalent circuit model

This paper proposes a modeling method of the motor broadband equivalent circuit model. The impedance amplitude-frequency characteristics of the motor terminal through measuring are obtained. The impedance amplitude-frequency characteristics are devided into several regions based on its first resonant point information,and the motor broadband circuit topology is developed with each region equaling a resonance unit. The RLC parameters of resonance unit are extracted through frequency and corresponding impedance of the any non-resonant and resonant point in each unit. This proposed method is used to build DC and AC motor broadband equivalent circuit model. Their impedance amplitude-frequency characteristics are simulated by the Saber software. The measurement results and the simulation result of references are compared. The DC motor simulation results coincide with the measurement results in 0.1~50 MHz,and the AC motor is in 0.1~40 MHz. The results show that the motor broadband circuit model is reliable and feasible.     

Integrate Reset Controlled Three Phase Power Factor Correction

A three phase power factor corrector in continuous current mode is introduced. The control equations are deduced and realized by Integrate reset controller. The integrate reset controller is composed of a integration with reset,a RS flip-flop and a comparator,which is very simple. The integrate reset controlled three phase power factor corrector has these characteristics as follows: Constant frequency operation, which is of advantage of the design of filter;the control circuit is simple and no need for multiplier;The result of simulation proves the correction of theory analysis.     

Multi-yesolution Encoding of Medical Image in PACS

It is necessary to transmit and review medical images effectively in PACS (Picture Archive & Communication System, PACS) , and multi -resolution encoding can improve image compression efficiency. The progressive property of 2D image wavelet transform is studied, and a multi - resolution medical image encoding method is described. This encoding method means that, the lower frequency subimage in wavelet domain should be encoded prior to those higher frequency subimage. Also, in the medical image process of transmission and reviewing, the same order will be followed. The experiment has improved that the proposed method can speedup the medical image transmission and reviewing in PACS effectively.     

Selection of the most efficient wavelength bands for ‘Jonagold’ apple sorting

This paper presents a method based on quadratic discriminant analysis to select the best filters for detecting a wide range of defects in ‘Jonagold’ apple fruit using a multi-spectral vision system. Reflectance spectra of damaged and sound tissue were recorded using a visible/NIR spectrometer. Analysed defects consisted of scald, hail damage (with and without skin perforation), limb rubs, russets, scab tissue, frost damage, rot, visible flesh damage and recent bruises. Camera filter effects were approximated by summing the reflectances of all the wavelengths within the filter bandwidth. Combinations of three and four filters were tested and evaluated for discriminating damaged tissues from healthy ones. If a three-filter combination appeared sufficient to detect most of the damaged tissue, a four-filter combination should be considered for the complete sorting automation of this bicolour apple variety. A fourth filter was necessary to quantify the ratio between the blush and ground colours. Regarding recent bruise defects which represented the major difficulty, an image segmentation algorithm based on local contrast variations can enhance their detection.     

Relationship between the City Central District''s Evolutionand The Formation of CBD

Agglomeration Effects and its evolution lead to the formation and further evolution to multi centers of a city's original center.During the further evolution to multi centers, there exists a rule which is proved to be true by the example of the formation and evolution of The dynamic adjustment of functions between business and trade within centersdrive the formation of a modern city's central business district(CBD).This rule discloses the following facts in planning and policy making of CBD:we must obey the natural rules of city centers' evolution,including the rules of Agglomeration Effects;we must lead CBD to mainly agglomerate business,not agglomerate everything;we can choose the original city center or other place out of the original city center as a CBD's location.