nils-herrmann/clean_scirepeval huggingface dataset:
Comparative analysis for various parametric attributes for an optimized DUC/DDC

In present digital communication system, sample rate conversion plays a crucial role in every aspect. Multirate signal processing can be realized by using Digital up/down converters. In this paper, an optimized model for digital up/down converter is analysed on the basis of various parametric attributes such as different interpolation/decimation factors, cascading of filters, adding delay element and number of sections in the CIC filter (N). The input signal in the range of 300–4000 Hz is sampled at 100 kHz. Further, the sampled signal is passed on to CIC filters along with a CIC compensator. The signal is either upsampled or downsampled by a factor of 12. Then, the up/down sampled signal is modulated with a high frequency carrier signal of 600 kHz generated using a direct digital synthesizer. The obtained output signal is an up/down sampled signal. The output is analysed for different parametric aspects to achieve an improvised Digital up/down converter. These filters are designed and simulated using MATLAB Simulink 2014a.
Connected vibrations method for non-rigid motion tracking

This paper introduces a new algorithm for tracking non-rigid motion in image sequences. Non-rigid motions are modelled as the deformations of connected 2D membrane patches. Local smoothness constraints for each patch are the low-frequency vibration modes obtained from modal analysis. Hinges are imposed between patches to maintain the global topological structure. The resulted over-constrained linear system is solved efficiently using a least square estimator. Promising results on both natural and synthetic facial motion sequences are demonstrated in this paper.
Alleviation of chattering in variable structure control signal for flexible one-link manipulator

A variable structure controller design for the tip position control of a flexible one-link manipulator was presented by Thomas et al. (1997). The control torque obtained using this design methodology was subjected to high frequency chattering. This makes it impossible to implement the controller in practice. The absence of a sign(S) function in the control law makes it impossible to implement the boundary layer technique of chatter reduction where the sign(S) function is replaced by a saturation type function to yield a continuous control signal approximation that confines the system trajectory to a small band neighboring the switching surface. This paper presents a new switching law which not only alleviates chattering in the control signal but also ensures ideal sliding mode motion. Simulation results are presented to verify the claims attributed to the proposed method.
Equilibrium and stability of free-running, phase-locked, and mode-locked quasi-optical gyrotrons

Equilibria and stability (both single-mode and sideband) are calculated and contrasted for free-running, phase-locked, and mode-locked oscillator configurations in a quasi-optical gyrotron. The oscillator can be phase locked by direct injection of radiation into the oscillator cavity. The equilibrium and stability properties are not greatly affected at low injection power levels. Alternatively, the oscillator could be phase locked by prebunching the beam. If the beam is prebunched, there are dramatic effects on both equilibrium and stability. The transverse efficiency can be considerably enhanced by prebunching the beam. This prebunching can be done on either a phase-locked (using an external RF source) or mode-locked (using the oscillator output) configuration. The stable locking bandwidth turns out to be about half the omega /Q linewidth of the mode.
An overview of Cree silicon carbide power devices

The compelling system benefits of using silicon carbide (SiC) Schottky diodes have resulted in rapid commercial adoption of this new technology by the power supply industry. Silicon carbide PiN diodes, MOSFET's, and BJT's, are approaching the point of development that they could be transitioned to volume production. This work reviews the characteristics of recently produced SiC devices including Schottky diodes, PiN diodes, MOSFET's, and BJT's. A comparison of the static and dynamic performance of the SiC devices and typical silicon devices is performed. The results show the performance improvement available with SiC devices. The high temperature performance capabilities of SiC devices are also highlighted.
Correlation Embedding Analysis

To design geometrically motivated approaches for classifying the high-dimensional data, we propose to learn a discriminant subspace using Correlation Embedding Analysis (CEA). This novel algorithm enhances its discriminant power by incorporating both correlational graph embedding and Fisher criterion. In a geometric interpretation, it projects the high- dimensional data onto a hypersphere and preserves intrinsic neighbor relations with the Pearson correlation metric. After the embedding, resulting data pairs from the same class are forced to enhance their correlation affinity, whereas neighboring points of different class are forced to reduce their correlation affinity at the same time. The feature learned by CEA is tolerable to scaling or outlier. Experiments on face recognition demonstrate the effectiveness and advantage of the CEA.
Backward wave gain due to nonlinear interaction with the fast space charge wave [forward wave amplifiers]

Slow wave circuits used in forward wave amplifiers like helix TWTs also support backward waves. A backward wave can interact with the slow and fast space charge waves of an unmodulated electron beam at frequencies at which the phase velocities of the waves are nearly equal. We have identified the positive backward wave gain due to the interaction of the fast wave and the first backward wave space harmonic in a helix TWT as being the primary physical mechanism responsible for so-called 'power holes' - dips in the output power vs. frequency curves in TWTs observed under large signal conditions. We speculate that this effect may be used as a diagnostic, in a way analogous to the use of the Kompfner dip.
A Computationally Efficient Two-Dimensional Model of the Beam–Wave Interaction in a Coupled-Cavity TWT

A new computationally efficient 2-D model of the beam-wave interaction in coupled-cavity traveling-wave tubes (CC-TWTs) has been developed. The model provides self-consistent time-dependent solutions of Maxwell's equations together with a fully relativistic solution of the electron equations of motion. The model is based on different treatments of the RF fields in the region occupied by an electron beam and in the region of the coupled-cavity structure. The RF fields inside the beam tunnel are represented as a sum of eigenmodes of the local cross section of the beam tunnel. The fields outside the beam tunnel are represented as a superposition of modes of an equivalent circuit with lumped capacitors, inductors, and resistors. The model has been implemented in the TESLA-CC code. The results of the code predictions agree well with measured data for a wideband CC-TWT operating in the Ka-band. The code also shows good agreement with predictions of the 1-D code CHRISTINE-CC in regimes in which a 1-D approximation is applicable. A numerical study of CC-TWT operation shows that, in the small-signal regime, the code is able to predict a gain enhancement due to transverse motion at focusing magnetic fields comparable with Brillouin equilibrium values, which is the major 2-D effect. In the large-signal regime, the code is also capable of treating cases in which the transverse displacement of electrons becomes large and of determining the dependence of the spent beam energy distribution on radial position.
Discriminative Exemplar clustering

Exemplar-based clustering methods partition the data space and identify the representative, or the exemplar, of each cluster. With the number of clusters adaptively determined, exemplar-based clustering methods are appealing since they avoid or alleviate the difficult task of estimating the latent parameters in case of complex models and high dimensionality of the data. Most exemplar-based clustering methods are based on generative models, where the exemplars serve as the parameters of the generative models. However, generative models do not consider the discriminative capability of the cluster boundaries explicitly described in discriminative models. In this paper, we present Discriminative Exemplar Clustering (DEC), that improves the discriminative power of exemplar-based clustering method by minimizing the misclassification error of the nonparametric unsupervised plug-in classifier while maintaining the appealing property of exemplar-based clustering. The optimization of DEC is performed in a pairwise Markov Random Field. Experimental results on synthetic and real data demonstrate the effectiveness of our method compared to other exemplar-based clustering methods.
3D face analysis for distinct features using statistical randomization

It is a fascinating yet challenging problem to accurately and efficiently localize regionally distinct features between face groups in multi-dimensional signal processing and analysis. Given a data with unknown distribution and small sample size, we propose a new statistical analysis framework using hybrid randomization (i.e., permutation) tests to improve the system's efficiency in identifying distinct features. The proposed method fits the nonparametric distribution of the test statistic with Pearson distribution series. We bypass the tedious online randomization via calculating the first four moments of the permutation distribution. This can reduce the computational complexity from O(n!) to O(n2) over traditional methods for the modified Hotelling's T2 test statistics. Experiments on simulated data and 3D face analysis demonstrate the efficiency, accuracy and robustness of the proposed approach.
A practical approach for locating faults for overhead transmission lines using synchronized measurements from PMUs

A synchophasor based scheme for locating faults on transmission lines is presented in this paper. The synchronized measurements are obtained from phasor measurement unit (PMU). The phasors of voltage and current at the two line terminals are acquired using PMUs installed at the two terminals. The impedance of the system at the time of fault is solved using suddenly changed positive sequence components of voltage and current those are obtained from the suddenly changed phasors of current and voltage. This system impedance is utilized in the calculation of the distance to fault. The proposed algorithm is applied to an 115kV system. Results revealed that the proposed scheme precisely locate the fault distance and is not affected by fault type and resistance.
A 62.5 Gb/s multi-standard SerDes IC

This paper describes a 20-lane 62.5 Gb/s SerDes designed as an interface between the 40G, or quad 10G Optics, and a downstream framer device. Transmit and receive clocks are derived from an LC-based PLL with a wideband RMS jitter below 2.5 ps. Timing recovery uses a 2/sup nd/ order loop and includes over-sampled /spl Delta//spl Sigma/ techniques to achieve both narrowband filtering and excellent jitter tolerance. To support backplane applications, line driver and receiver incorporate preemphasis and equalization respectively.
Combining genetic oscillators and switches using evolutionary algorithms

It is hypothesised that complex biological gene regulatory networks can be evolved from simple networks through modularisation, duplication and specialisation processes. However, the biological mechanisms of this process remain elusive and little work has been done to verify this hypothesis in a computational environment. This paper aims to couple two simple regulatory motifs, one toggle switch and one self-sustained oscillator using an evolutionary algorithm, which can be seen as a computational simulation of natural evolution. We have successfully evolved several complex dynamics for two different connections arrangements between the oscillator and toggle switch networks in a master/slave set up, which confirms the previously reported results achieved manually. Our results indicate that generating complex dynamics by coupling of simple motifs using simulated evolutionary mechanisms is methodologically feasible and more efficient, which can be seen as an indirect and partial verification of the above hypothesis.
Algorithms and experimental results on image reconstruction from limited data

Multidimensional imaging of three dimensional (3-D) objects is often complicated by physical constraints imposed by the observation technique. An example of this problem occurs in 3-D imaging of specimens with electron-microscopes. In this case the range of observation angle (perspective) is typically less than π/2 radians due to the limited angle through which the specimen can be rotated relative to the electron beam. This paper presents three novel algorithms that significantly enhance the resolution of techniques limited by lack of perspective. The methods are based on a combination of Gerchberg's spectral error energy reduction algorithm (1) and tomographic image reconstruction techniques.
Emotion recognition from audiovisual information

We report preliminary results on emotion recognition by machine from joint audiovisual input of facial video and speech. The results show potential advantages in using both modalities over either modality alone. The recognition rate for audio alone is about 75% and video alone about 70%. Using audiovisual data we achieved 97% without increasing the number of features. The improvement in performance is accredited to the complementary property between the two modalities. A possible application is in natural human-computer interfaces.
Effects of random circuit fabrication errors on the mean and standard deviation of small signal gain and phase in a traveling wave tube

This paper summarizes a calculation of the mean and standard deviation of the small signal gain and phase of a TWT in the presence of small random, axially varying perturbations in the circuit phase velocity using numerical and analytic approaches. The analytical results compare favorably with results from numerical computations in the absence of space charge effects. The effects of small pitch errors in a 210 GHz folded waveguide TWT are evaluated in an example.
Design of a Ka-band gyro-TWT for radar applications

Extending the bandwidth and average power capability of vacuum electron devices for the next generation of millimeter wave radars is a major research goal at the Naval Research Laboratory. Gyro-amplifiers such as the gyroklystron and gyro traveling wave-tube (gyro-TWT) appear to be ideal candidates for this purpose due to their high power handling capability relative to their conventional counterparts, i.e., klystrons and coupled-cavity TWTs. This paper presents the design of a high-average power compatible, Ka-band gyro traveling-wave-tube (gyro-TWT). This amplifier design employs the circular TE/sub 11/ mode and operates at the fundamental cyclotron harmonic. In addition, this design makes use of the distributed loss approach, which has recently been demonstrated to be effective in the suppression of spurious oscillations in gyro-TWTs. The design has been performed using the self-consistent, time-dependent, quasi three-dimensional code MAGY. The code has been successfully used to model gyroklystrons and benchmarked against gyro-TWT linear theory. The code is capable of addressing issues such as absolute instabilities and the effect of reflections, which have also been investigated for this design.
Effects of Multiple Internal Reflections on the Small-Signal Gain and Phase of a TWT

We formulate and solve a set of equations that model the effects of reflections from an arbitrary number of circuit discontinuities in a traveling-wave tube (TWT) operating under small-signal conditions. Applying this model to a case in which the discontinuities represent a series of small random pitch variations due to fabrication errors in a helix TWT, we find that reflections may significantly increase the statistical effects on the gain and output phase first reported in the work of Pengvanich In another example, we report on a study of the effects of many small pitch errors on gain ripple in a 220-GHz folded waveguide TWT.
A Battery-Free Multichannel Digital Neural/EMG Telemetry System for Flying Insects

This paper presents a digital neural/EMG telemetry system small enough and lightweight enough to permit recording from insects in flight. It has a measured flight package mass of only 38 mg. This system includes a single-chip telemetry integrated circuit (IC) employing RF power harvesting for battery-free operation, with communication via modulated backscatter in the UHF (902-928 MHz) band. An on-chip 11-bit ADC digitizes 10 neural channels with a sampling rate of 26.1 kSps and 4 EMG channels at 1.63 kSps, and telemeters this data wirelessly to a base station. The companion base station transceiver includes an RF transmitter of +36 dBm (4 W) output power to wirelessly power the telemetry IC, and a digital receiver with a sensitivity of -70 dBm for 10-5 BER at 5.0 Mbps to receive the data stream from the telemetry IC. The telemetry chip was fabricated in a commercial 0.35 μ m 4M1P (4 metal, 1 poly) CMOS process. The die measures 2.36 × 1.88 mm, is 250 μm thick, and is wire bonded into a flex circuit assembly measuring 4.6 × 6.8 mm.
Automatic generation of boundary conditions using demons nonrigid image registration for use in 3-D modality-independent elastography.

Modality-independent elastography (MIE) is a method of elastography that reconstructs the elastic properties of tissue using images acquired under different loading conditions and a biomechanical model. Boundary conditions are a critical input to the algorithm and are often determined by time-consuming point correspondence methods requiring manual user input. This study presents a novel method of automatically generating boundary conditions by nonrigidly registering two image sets with a demons diffusion-based registration algorithm. The use of this method was successfully performed in silico using magnetic resonance and X-ray-computed tomography image data with known boundary conditions. These preliminary results produced boundary conditions with an accuracy of up to 80% compared to the known conditions. Demons-based boundary conditions were utilized within a 3-D MIE reconstruction to determine an elasticity contrast ratio between tumor and normal tissue. Two phantom experiments were then conducted to further test the accuracy of the demons boundary conditions and the MIE reconstruction arising from the use of these conditions. Preliminary results show a reasonable characterization of the material properties on this first attempt and a significant improvement in the automation level and viability of the method.
Effect of gas switching on InP/InGaAs interfaces during CBE growth

In this paper, the effect of a simple gas switching sequence on interface abruptness during CBE growth is studied using double crystal X-ray diffraction (DCXRD), photoluminescence (PL), and scanning tunneling microscopy (STM). Optimization of the switching sequence produces monolayer abruptness for both the InP/InGaAs and the InGaAs/InP interfaces.
3D MIMO Outdoor-to-Indoor Propagation Channel Measurement

The 3-D multiple-input multiple-output (3-D MIMO) systems have received great interest recently because of the spatial diversity advantage and capability for full-dimensional beamforming, making them promising candidates for practical realization of massive MIMO. In this paper, we present a low-cost test equipment (channel sounder) and post-processing algorithms suitable for investigating the 3-D MIMO channels as well as the results from a measurement campaign for obtaining elevation and azimuth characteristics in an outdoor-to-indoor (O2I) environment. Due to limitations in available antenna switches, our channel sounder consists of a hybrid switched/virtual cylindrical array with effectively 480 antenna elements at the base station. The virtual setup increased the overall MIMO measurement duration, thereby introducing phase drift errors in the measurements. Using reference antenna measurements, we estimate and correct for the phase errors during post-processing. We provide the elevation and azimuth angular spreads for the measurements done in an urban macro-cellular and urban micro-cellular environments, and study their dependence on the user equipment (UE) height. Based on the measurements done with UE placed on different floors, we study the feasibility of separating users in the elevation domain. The measured channel impulse responses are also used to study the channel hardening aspects of the massive MIMO and the optimality of the maximum ratio combining receiver.
A quantitative evaluation for 3D face reconstruction algorithms

In this work, we proposed to use quantitative method to evaluate the accuracy of 3D face reconstruction algorithms. The reconstructed 3D faces are first aligned to the ground truth by Iterative Closest Point (ICP) algorithm and then the shape difference between the two 3D faces is described by Signal to Noise Ratio (SNR). Finally, the error maps (EM) illustrated the reconstruction errors on corresponded vertices in different dimensions. Comparing with the subjective and indirect evaluation methods, the proposed method provides more precise and detailed evaluations for face shape reconstruction. Based on the SNR, different 3D face reconstruction algorithms can be compared directly and the EM also can suggest guidance for feature extraction.
Detection of small moving objects in image sequences using multistage hypothesis testing

The detection of small, low-contrast, moving objects in a time sequence of digital images is addressed. Since object positions and velocities are unknown, a large number of candidate trajectories, organized into a tree-structure, are hypothesized at each pixel. At each 'root' image pixel, trajectory extensions are mapped to tree nodes. Pixels along a trajectory are tested sequentially for a shift in mean intensity using multistage hypothesis testing (MHT). The MHT is designed according to prespecified error probabilities. Exact, closed-form expressions for MHT test performance are derived and then applied to predicting the algorithm's computation and memory requirements. Under a Gaussian white noise background assumption it is shown theoretically that over 4000 candidate trajectories per pixel are tested using an average of only 30 additions and threshold comparisons.<<ETX>>
Detection of time-varying support via rank evolution approach for effective joint sparse recovery

Efficient recovery of sparse signals from few linear projections is a primary goal in a number of applications, most notably in a recently-emerged area of compressed sensing. The multiple measurement vector (MMV) joint sparse recovery is an extension of the single vector sparse recovery problem to the case when a set of consequent measurements share the same support. In this contribution we consider a modification of the MMV problem where the signal support can change from one block of data to another and the moment of change is not known in advance. We propose an approach for the support change detection based on the sequential rank estimation of a windowed block of the measurement data. We show that under certain conditions it allows for an unambiguous determination of the moment of change, provided that the consequent data vectors are incoherent to each other.
Broadband dual polarized antenna arrays for mobile communication applications

This paper discusses design issues for uniform rectangular antenna arrays and the requirements for channel sounding applications. Two different array realizations are presented. The first array is based on Vivaldi antennas the second on patch antennas. The arrays consist of 32 dual polarization-sensitive radiators. Both arrays operate at 2 GHz, covering the uplink and downlink bands of the UMTS standard. The resulting performance of the arrays is compared and discussed.