Differential Filter Research Articles

Use of machine intelligence to conduct analysis of human brain data for detection of abnormalities in its cognitive functions

The physical appearance of a brain tumor in human beings may be an indication of problems in psychological (cognitive) functions. Such functions include learning, understanding, problem solving, decision making, and planning. Early brain tumor detection can be done by using the proper procedure of screening. MRI is used for the detection of disease staging and follow-up without ionization radiation. In this manuscript, an automated system is proposed for the analysis of brain data and detection of cognitive functions abnormalities. The region of interest (ROI) is enhanced using a proposed partial differential diffusion filter (PDDF) which is a modified form of anisotropic diffusion filter. Otsu algorithm is used for better segmentation. Moreover, a new method is also proposed for feature extraction which is a concatenation of local binary pattern (LBP) and Gray level co-occurrence matrix (C2LBPGLCM). The proposed method accurately distinguishes between healthy and unhealthy images with high specificity, sensitivity, and area under the curve.

Research on Simultaneous Location and Mapping Algorithm of Intelligent vehicle Based on Improved Particle Filter Resampling

For the estimation problem that the Simultaneous Location and Mapping algorithm used in Intelligent vehicle suffers from sample impoverishment, a Multi-threshold differential evolutionary particle resampling method is proposed. The method adopts different particle updating Strategys according to different thresholds of effective particle numbers. particle diversity will be rapidly improved by differential evolution when particle degradation is severe. When the particle degradation is light, the system resampling method is directly used to copy the large weight particles and eliminate the small weight particles. By adopting different particle regeneration strategies for particles with different degrees of degradation, the problem of particle degradation and depletion in the process of state estimation can be effectively solved. Simulation experiments show that the root mean square error of the improved algorithm pose is reduced by 2.592m compared with the traditional algorithm. The road sign estimation root mean square error is also reduced by 2.428m compared with the traditional algorithm. Experiments show that the multi-threshold differential particle filter resampling method can effectively improve the particle diversity and ensure the state estimation accuracy of the vehicle.

Differential Dual-Band Superconducting Bandpass Filter Using Multimode Square Ring Loaded Resonators With Controllable Bandwidths

In this paper, a fourth-order dual-band high-temperature superconducting (HTS) differential bandpass filter (BPF) with controllable midband frequencies and bandwidths is developed by using modified multimode square ring loaded resonators (SRLRs). The differential-mode (DM) bisection and common-mode (CM) bisection of the modified SRLR are analyzed by using the even- and odd-mode method twice, and the corresponding resonant properties are obtained. With a proper design of the modified SRLR, two lowest DM resonances are chosen to construct two DM passbands with high in-band CM suppression. The DM resonances can be adjusted flexibly after adding tunable patches to the square ring. Meanwhile, the internal coupling between two modified SRLRs can be controlled separately by using two geometrical parameters. Consequently, the proposed dual-band BPF can achieve independent control of both the midband frequencies and the bandwidths of its two passbands. Moreover, a wideband CM suppression is realized by a combined use of an appropriately selected feeding structure and a frequency discrepancy technique. A fourth-order dual-band differential BPF is designed with two passbands operating at 2.325 and 4.900 GHz, respectively. The filter is fabricated using HTS YBCO thin films on a MgO substrate. Good agreement between the simulated and measured frequency responses are observed, verifying well the proposed structure and design method.

Design Wideband Differential Bandpass Filter Using Slotline Surface Plasmon Polaritons

In this paper, a novel wideband differential bandpass filter (BPF) with slotline surface plasmon polaritons (SPPs) is proposed. It consists of a pair of differential microstrip-to-slotline transition, a slotline-to-SPP transition with subwavelength gradient grooves, and a slotline SPP waveguide, which supports the TEM, TE, and SPP modes, respectively. The dispersion and transmission characteristics of the proposed hybrid SPP structure are analyzed under differential-mode (DM) and common-mode (CM) operations and applied to design wideband differential filter. To validate the design concept, a filter sample has been designed, fabricated, and measured. Both simulated and measured results prove its good performance including a wide 3-dB fractional bandwidth of 147.6% centered at 4.2 GHz (f 0 ), a wide DM upper stopband to 4.8 f 0 (S 21 dd <; -30 dB), and a wide 40-dB CM suppression from 0.1 to 20 GHz.

A new microstrip coupling system for realization of a differential dual-band bandpass filter

In this paper, a new Differential Dual-Band Wide-Bandpass Filter (DDWBF) using a new coupling system is presented. The adjustable coupling system composed of Two Coupled U-Shaped Structures (TCUSs) which create and control two initial passbands. Four TCUSs are then placed in four ports and connected through a defected fractal-based low impedance transmission line. Third order of Sierpinski fractal is applied on the transmission line to improve the out of band rejection of the differential mode along with common mode suppression. An analytical analysis is also presented to calculate the transmission zeros and poles of the DDWBF which verifies the authenticity of the design procedure. A prototype of the filter has been fabricated and tested which shows a very good agreement with the predicted results. According to the measured results, two wide passbands with fractional bandwidths of 45% and 13.5% at central frequencies of 4.32 and 8.61 GHz, respectively, have been achieved. The differential mode return loss is higher than 15 dB in both bands and the common mode suppression level is better than 14.85 dB.

A 0.9-nW, 101-Hz, and 46.3-&lt;inline-formula&gt; &lt;tex-math notation="LaTeX"&gt;$\mu$ &lt;/tex-math&gt; &lt;/inline-formula&gt;Vrms IRN Low-Pass Filter for ECG Acquisition Using FVF Biquads

This paper presents a differential fourth-order low-pass filter suitable for electrocardiography (ECG) acquisition. It is formed by cascading two compact and power-efficient biquads operating in the subthreshold region. Each biquad combines two capacitors and a flipped voltage follower circuit. The filter attains a cutoff frequency adjustable to cover the entire range of ECG (150–250 Hz). The filter prototype has been fabricated in a 0.35- $\mu \text{m}$ CMOS technology. It occupies an area of $362\,\,\mu \text {m} \times 466 \,\,\mu \text{m}$ and operates from a 0.6-V supply. Measurements confirm that the filter consumes 0.9-nW static power for a 101-Hz cutoff frequency and contributes the input-referred noise of 46.27 $\mu \text{V}_{\mathbf {rms}}$ . For a 60-Hz input frequency, the filter achieves a dynamic range of 47 dB where the third-harmonic distortion of −60 dB is produced. This leads to the figure of merit of $46.5 \times 10^{-18}$ J. When the chip area is also concerned, the proposed filter performs comparably to the recent state-of-the-art nanowatt-class low-pass filter.

Microgrid Islanding Detection Based on Mathematical Morphology

Voltage and frequency stability are highly important for reliable performance of smart grids. In grid-connected mode, the utility controls these parameters, but when islanding occurs these parameters exceed their limits, which may result in irreparable damage to the system. This paper presents a time-domain approach which uses basic mathematical morphology (MM) operators, dilation and erosion filters, for microgrid islanding detection. The proposed method applies a dilation-erosion differential filter (DED) of the RMS signal (DEDFOR) at the point of common coupling (PCC) in a micro-grid connected to distributed generations (DGs). To evaluate the performance of the proposed approach, it is tested and compared with existing techniques in the literature under various conditions such as capacitor bank switching and motor starting. The results verify the accuracy and efficiency of the proposed technique for islanding detection under different operating conditions and various power mismatches.

Direct synthesis of compact wideband differential bandpass filter on composite triple-mode resonator

In this paper, a direct synthesis approach is proposed for design of a compact wideband differential-mode (DM) bandpass filter (BPF) on a composite triple-mode resonator. By virtue of intrinsic common-mode (CM) suppression in slotline portion, only the DM transmission performances need to be focused on in our design, so as to facilitate the design process. Consequently, a synthesis approach based on an equivalent simplified network is established to design this DM BPF, resulting to directly determine all the circuit element values. A wideband DM BPF is then designed to validate effectiveness of proposed synthesis method. Finally, two circuit prototypes have been designed, fabricated, and measured. The synthesized, simulated and measured results agree well with each other over a wide operating band, which has demonstrated the proposed DM BPFs' attractive performances, such as wide bandwidth of operation, sharpened frequency selectivity, and good CM suppression.

Wideband Tunable Differential Bandstop Filter Based on Double-Sided Parallel-Strip Line

This paper presents a wideband tunable differential bandstop filter (BSF) using optimized varactor-loaded stepped-impedance resonators (SIRs) based on the double-sided parallel-strip line (DSPSL). A detailed investigation on the relationship between the frequency tunability and the properties of the SIR is presented. It can be found that there are two extra factors for determining frequency-tuning range of the varactor-loaded SIR, i.e., the impedance and length ratios, in addition to the variation range of the varactor’s capacitance. Thanks to the balanced properties of the DSPSL, the common mode shows all-stop response. For demonstration, a second-order wideband tunable differential BSF using two varactor-loaded DSPSL SIRs is designed, and the design procedures are given in detail. The simulation and measured results, showing good accordance, exhibit a tuning range from 0.58 to 1.07 GHz, corresponding to a fractional tuning range of 59.4%.

Miniaturized Dual-Band Differential Filter Based on CSRR-Loaded Dual-Mode SIW Cavity

In this letter, a miniaturized differential substrate-integrated waveguide (SIW) bandpass filter with dual-band response has been illustrated. Two complementary split-ring resonators are etched on the top metal layer. According to the theory of evanescent-mode propagation, a differential-mode (DM) passband below the waveguide cutoff can be obtained. Next, the fundamental frequency of the SIW cavity can be tuned closely to the second harmonic by partially removing the dielectric material inside the SIW cavity which constructs another DM passband. With the proper positions of the feeding lines, the third harmonic can also be well suppressed. Moreover, good common-mode suppression has been achieved for the employment of the proposed balanced structure and the center frequencies of the two DM passbands can be flexibly controlled. A differential filter operating at 6.22 and 8.24 GHz has been realized and fabricated to validate the design idea.

Reconfigurable Differential Filter With Constant Absolute Bandwidth and High Common-Mode Suppression

A reconfigurable differential filter with constant absolute bandwidth (ABW) and high common mode (CM) suppression is proposed in this letter. The design is aiming to achieve the constant ABW under the differential mode (DM) by choosing the loading place of the varactors on the resonators and adjusting the external quality factor. Under the DM and CM bisection, the frequency of the CM differs from that of the DM, which results in the wide CM suppression without loading extra elements. The transmission zeros are introduced by source–load coupling, which lead to high selectivity. The simulated and measured results are presented with a good agreement to verify the theory and design.

Hyperspectral image compression based on simultaneous sparse representation and general-pixels

Simultaneous sparse representation can transform the correlated spectral signatures of hyperspectral pixel matrixes into sparse coefficients. It can be very efficient in the compression scheme when the original image is clustered to general-pixels (a cluster of hyperspectral pixels which contains the similar signature). In this paper, we propose a simultaneous sparse representation based hyperspectral image compression scheme. First, the whole hyperspectral pixels are clustered into general-pixels and each general-pixel will be coded by the simultaneous sparse representation scheme. To further compress the coefficients, the differential pulse code modulation filter is adopted in each row coefficients. Finally, all the nonzero coefficients, over-complete dictionary and mapping data of general-pixels will be transformed into the binary bitstream by Huffman coding. The results on four hyperspectral image datasets show that our method outperforms several classical and the state-of-the-art methods in term of rate-distortion and spectral fidelity performance.

A new approach to the push–push oscillator based on a differential SIW bandpass filter

ABSTRACTA novel push–push oscillator based on a differential bandpass filter (BPF) using substrate integrated waveguide (SIW) technique is presented in this paper. For the first time, the differential SIW BPF is utilized as a frequency stabilization element to provide differential outputs in designing the push–push oscillator. The complex quality factor (Qsc)-peak frequency of the BPF is chosen for the design at approximately half the final output frequency to achieve low phase noise performance. Moreover, two transmission zeros (TZs) below the passband and two TZs above the passband which highly improve the out-of-band rejection are obtained by using both electromagnetic coupling and cross coupling. An SIW power combiner is also designed to obtain the desired signal. A push–push oscillator has been proposed and experimentally demonstrated at 27.8 GHz to verify the above design concept. The measured results show that the output power is −17.3 dBm with a phase noise of 128.6 dBc/Hz at 1-MHz offset.

An Area-Efficient DC Offset Cancellation Architecture for Zero-IF DVB-H Receivers

This letter presents a new dc offset cancellation structure for zero-IF receivers. A very small occupied area is the main advantage of this structure. The differential high-pass filter based on this structure, which has been implemented in the 0.18- $\mu \text{m}$ CMOS technology, achieves a lower cutoff frequency of 180 Hz. The occupied silicon area is less than 0.167 mm2. The gain variation of this filter is less than 0.3 dB at the frequency range of 700 Hz–3.8 MHz. Moreover, the IIP3 is better than 29 dBm. This filter draws 1.48 mA from the 1.8 V voltage supply, and it is able to tolerate ±45 mV input differential dc offset.

Thermal Temperature Measurements of Inertial Fusion Implosions

Accurate measurement of the thermal temperature in inertially confined fusion plasmas is essential for characterizing ignition performance and validating the basic physics understanding of the stagnation conditions. We present experimental results from cryogenic deuterium-tritium implosions on the National Ignition Facility using a differential filter spectrometer designed to measure the thermal electron temperature from x-ray continuum emission from the stagnated plasma. Furthermore, electron temperature measurements, used in conjunction with the Doppler-broadened DT neutron spectra, allow one to infer the partition of energy in the hot spot between internal energy and unconverted kinetic energy.

Fast Von Mises strain imaging on ultrasound carotid vessel wall by flow driven diffusion method.

The elasticity of the vessel wall is important for the clinical identification of rupture-risks. The Von Mises strain can be a potential index for the indication of carotid vessel pathologies. In this paper, a fast clinically applicable real-time algorithm from time-sequence of B-mode carotid images is developed. Due to the compression induced by the normal cardiac pulsation, tissue motion occurs radially and non-rigidly. To obtain an accurate motion field, we developed a variational functional integrating the optical flow equation and an anisotropic regularizer, and designed a diffusion tensor to encourage coherence diffusion. The motion field is smoothed along the desired motion flow orientation. A fast, additive operator splitting scheme, which is ten times faster than the conventional discrete method, is used for the numerical implementation. To demonstrate the efficiency of the proposed approach, finite element models are set up for normal and pathological carotid vessel walls. The results indicate that the proposed diffusion approach obtains an accurate smooth and continuous motion field and greatly improves the follow up strain estimation using a fast differential strain filter. Furthermore, our approach using the Von Mises strain imaging on clinical ultrasound images of the carotid artery is validated. Participants above 65-years in age suffering from different stages of atherosclerosis in their carotid artery are selected. The results are evaluated by an experienced physician. The evaluation results demonstrate that the Von Mises strain has a good correspondence to the presence of certain suspicious areas in the B-mode images. The proposed method is therefore clinically applicable for the real-time Von Mises strain imaging of carotid vessel walls, and can be of great value as a complementary method to B-mode image for the clinical identification of the risk of plaque vulnerability.

Miniaturized Dual-Band Differential Filter Using Dual-Mode Dielectric Resonator

In this letter, a dual-mode dielectric resonator (DR) which is directly mounted on the bottom of metal cavity is investigated and utilized to design differential bandpass filter (BPF) with dual-band response. The bottom metal plate acts as an electric wall for a pair of dominant modes, resulting in a half-size reduction of the DR. According to the electric-field distributions of dominant modes and Ampere’s right-hand screw rule, the proposed dual-mode DR that owns two orthogonal half-TE $11\delta $ dominant modes can be still differentially excited conveniently and applied to construct dual-band differential-mode (DM) frequency response in the design of differential BPF. Meanwhile, the common-mode response can be suppressed to a great extent in a wide frequency range. A transmission zero between the two DM passbands can be generated to improve the band-to-band isolation. Finally, a differential DR BPF with dual-band response is given to verify the proposed idea.

Estimates of the discrete van Cittert deconvolution error in approximate deconvolution models of turbulence in bounded domains

Recent turbulence models such as the Approximate Deconvolution Model (ADM) or the Leray-deconvolution model are derived from the Navier–Stokes equations using the van Cittert approximate deconvolution method. As a consequence, the numerical error in the approximation of the Navier–Stokes weak solution with discrete solutions of the above models is influenced also by the discrete deconvolution error u−DNu‾h caused by the approximate deconvolution method. Here u is the flow field, u‾ is its average and DN is the N-th order van Cittert deconvolution operator.It is therefore important to analyze the deconvolution error u−DNu‾h in terms of the mesh size h, the filter radius α and the order N of the deconvolution operators used in the computation.This problem is investigated herein in the case of bounded domains and zero-Dirichlet boundary conditions. It is proved that on a sequence of quasiuniform meshes the L2 norm of the discrete deconvolution error convergences to 0 in the order of hk+1+KNh provided that the filter radius is in the order of the mesh size and the flow field has enough regularity. Here K<1 is a parameter that depends on the ratio (filter radius)/(mesh size) (which is assumed constant) and k is the order of the FE velocity space. The rate of convergence of the H1 norm of the error is also provided. The estimates are valid for the differential and Stokes filters. The result proves that higher order deconvolution operators decrease the deconvolution error and can be used to increase accuracy in approximate deconvolution models of flow problems.

Bounded adaptive output feedback tracking control for flexible-joint robot manipulators

This paper presents a bounded adaptive output feedback tracking control approach for flexible-joint robot manipulators with parametric uncertainties and bounded torque inputs, from a systematic perspective of different (weak or strong) joint flexibilities. The singular perturbation theory and integral manifold concept are applied to decouple the dynamics of flexible-joint robot manipulators into a slow subsystem and a fast subsystem. A class of saturation functions is used to make the control law bounded, ensuring the torque control inputs are within the output limitation of the joint actuators. An adaptive control law of the projection type is adopted to handle the feed-forward term of the slow sub-controller with parametric uncertainties. Meanwhile, an approximate differential filter and a high-gain observer are utilized in the slow and fast subsystems, respectively, to estimate the unmeasurable states, making the complete closed-loop control with only position measurements of motors and links. Importantly, a corrective control scheme is proposed to break through the traditional singular perturbation approach and to make it feasible for robot manipulators with strong joint flexibility. Furthermore, an all-round and strict stability analysis of the whole control system is given. Finally, simulation results verify the superior dynamic performance of the proposed approach.

Identification of the platform with electric drive using a differentiating filters

The paper presents an example of solving the parameter identification problem in case of platform with one degrees of freedom has been also presented. The parameter identification algorithm based on linear parameterization of the platform model and the least square criteria is developed. The desired derivatives of measured signals are estimated by means of designed differentiation filters. The required derivative order depends on the order of differential equations describing the object. The model was identified and verified using measurement results obtained for a real system.