Showing papers on "Offset (computer science) published in 2019"

Analysis and Design of Regenerative Comparators for Low Offset and Noise

Abstract: We make the case that in most comparators, offset and noise are determined by a dynamic preamplifier always embedded ahead of a regenerative latch. An analysis of this amplifier follows, from which simple expressions are obtained for input-referred offset and noise bandwidth. Practical circuit methods to compensate offset and lower noise become evident. We compare the StrongArm comparator with the double tail topology, and identify requirements for correct operation.

A Simplified MPFC With Capacitor Voltage Offset Suppression for the Four-Switch Three-Phase Inverter-Fed PMSM Drive

Abstract: This paper proposes a simplified model predictive flux control (S-MPFC) for a four-switch three-phase inverter (FSTPI)-fed permanent-magnet-synchronous-motor (PMSM) drive system with the consideration of capacitor voltage offset suppression. A stator flux compensator is introduced to fulfill the capacitor voltage offset suppression. A reference stator flux vector is obtained to represent the reference flux, the reference torque, and the capacitor voltage offset based on the ${\boldsymbol i}_{\boldsymbol d}$ = 0 control mode. Therefore, the flux vector is taken as the only control term in the cost function without any dreary weighting factor tuning work. Moreover, an offset flux error is defined according to the inherent features of the FSTPI, therefore, the optimal voltage vector can be selected in the stationary reference frame using a simple sector division and only one prediction calculation. Experimental results validate the effectiveness of the proposed S-MPFC.

Dynamic Performance Improvement of a Current Offset Error Compensator in Current Vector-Controlled SPMSM Drives

Abstract: The offset voltage variation of current sensors is mainly due to the thermal drift, and it causes torque ripples in current vector-controlled surface permanent magnet synchronous motor (SPMSM) drives. This paper proposes a current offset error compensator for the current vector-controlled SPMSM drives used in robotic applications, wherein dynamic movements frequently occur. The current offset error compensator for this kind of applications should provide a stable performance in estimating current offset errors during dynamic movements. Especially, the current offset error compensator should be able to suppress interferences from outer-loop controllers. In this paper, analysis on a synchronous frame current regulator is performed to see the relation between current commands and measured currents under the current offset error existing condition. The analysis shows that pure current offset error components can be obtained by subtracting low-pass filtered current commands from measured currents in a synchronous reference frame. It means that the interference from current commands in correcting current offset errors can be easily decoupled by the simple subtraction process, and the dynamic control capability of a current offset error compensator could be significantly improved. The dynamic performance of the proposed current offset error compensator is proved through simulations and experiments.

A 65-nm CMOS 6-bit 2.5-GS/s 7.5-mW 8 $\times$ Time-Domain Interpolating Flash ADC With Sequential Slope-Matching Offset Calibration

Abstract: A 6-bit 2.5-GS/s $8\times $ dynamic interpolating flash analog-to-digital converter (ADC) with an offset calibration technique for interpolated voltage-to-time converters (VTCs) is presented for high-speed applications. The dynamic-amplifier-structured VTC enables linear zero-crossing (ZX) interpolation in the time domain with an interpolation factor of 8, which reduces the number of front-end VTCs to one-sixth the original structure. The reduced number of VTCs lowers the power consumption, load capacitance to the track-and-holder (T/H), and overhead of VTC offset calibration. The sequential slope-matching offset calibration scheme is proposed not only for VTC offset but also for interpolated ZX accuracy. The prototype 6-bit 2.5-GS/s flash ADC was implemented in a 65-nm CMOS process and occupies a 0.12 mm2 chip area, including offset calibration circuitry. The measured differential non-linearity (DNL) and integral non-linearity (INL) after offset calibration are 0.68 and 0.65 LSB, respectively. With a 1.23 GHz input, the measured signal-to-noise and distortion ratio (SNDR) and spurious-free dynamic range (SFDR) are 33.84 and 45.07 dB, respectively, with power consumption of 7.5 mW under a supply voltage of 0.85 V. The prototype ADC achieves a figure of merit (FoM) of 74.7 fJ/conversion step at 2.5 GS/s.

Analysis and optimal individual pitch control decoupling by inclusion of an azimuth offset in the multiblade coordinate transformation

Abstract: With the trend of increasing wind turbine rotor diameters, the mitigation of blade fatigue loadings is of special interest to extend the turbine lifetime. Fatigue load reductions can be partly accomplished using individual pitch control (IPC) facilitated by the so-called multiblade coordinate (MBC) transformation. This operation transforms and decouples the blade load signals in a yaw-axis and tilt-axis. However, in practical scenarios, the resulting transformed system still shows coupling between the axes, posing a need for more advanced multiple input multiple output (MIMO) control architectures. This paper presents a novel analysis and design framework for decoupling of the nonrotating axes by the inclusion of an azimuth offset in the reverse MBC transformation, enabling the application of simple single-input single-output (SISO) controllers. A thorough analysis is given by including the azimuth offset in a frequency-domain representation. The result is evaluated on simplified blade models, as well as linearizations obtained from the NREL 5–MW reference wind turbine. A sensitivity and decoupling assessment justify the application of decentralized SISO control loops for IPC. Furthermore, closed-loop high-fidelity simulations show beneficial effects on pitch actuation and blade fatigue load reductions.

Adaptive MPC under Time Varying Uncertainty: Robust and Stochastic

Abstract: This paper deals with the problem of formulating an adaptive Model Predictive Control strategy for constrained uncertain systems. We consider a linear system, in presence of bounded time varying additive uncertainty. The uncertainty is decoupled as the sum of a process noise with known bounds, and a time varying offset that we wish to identify. The time varying offset uncertainty is assumed unknown point-wise in time. Its domain, called the Feasible Parameter Set, and its maximum rate of change are known to the control designer. As new data becomes available, we refine the Feasible Parameter Set with a Set Membership Method based approach, using the known bounds on process noise. We consider two separate cases of robust and probabilistic constraints on system states, with hard constraints on actuator inputs. In both cases, we robustly satisfy the imposed constraints for all possible values of the offset uncertainty in the Feasible Parameter Set. By imposing adequate terminal conditions, we prove recursive feasibility and stability of the proposed algorithms. The efficacy of the proposed robust and stochastic Adaptive MPC algorithms is illustrated with detailed numerical examples.

Investigation of Speech Landmark Patterns for Depression Detection

Abstract: The massive and growing burden imposed on modern society by depression has motivated investigations into early detection through automated, scalable and non-invasive methods, including those based on speech. However, speech-based methods that capture articulatory information effectively across different recording devices and in naturalistic environments are still needed. This article proposes two feature sets associated with speech articulation events based on counts and durations of sequential landmark groups or n-grams. Statistical analysis of the duration-based features reveals that durations from several consecutive landmark bigrams and onset-offset landmark pairs are significant in discriminating depressed from non-depressed speakers. In addition to investigating different normalization approaches and values of n for landmark n-gram features, experiments across different elicitation tasks suggest that the features can be tailored to capture different articulatory aspects of depressed voices. Evaluations of both landmark duration features and landmark n-gram features on the DAIC-WOZ and SH2 datasets show that they are highly effective, either alone or fused, relative to existing approaches.

Low-Complexity Superresolution Frequency Offset Estimation for High Data Rate Acoustic OFDM Systems

Abstract: This paper addresses the problem of compensating for motion-induced Doppler frequency offset in multicarrier acoustic communication systems based on orthogonal frequency-division multiplexing (OFDM). In mobile acoustic systems, Doppler effect can be severe enough that the received OFDM signal experiences nonnegligible frequency offsets even after initial resampling. To target these offsets, a superresolution, yet low-complexity method based on a stochastic gradient approach is proposed. The method relies on differentially coherent detection that keeps the receiver complexity at a minimum and requires only a small pilot overhead. Differential encoding is applied across carriers, promoting the use of a large number of closely spaced carriers within a given bandwidth. This approach simultaneously supports frequency-domain coherence and efficient use of bandwidth for achieving high bit rates. While frequency synchronization capitalizes on differentially coherent detection, it can also be used as a preprocessing stage in coherent receivers without creating undue complexity. Using simulation, as well as the experimental data transmitted over a 3–7-km shallow-water channel in the 10.5–15.5-kHz acoustic band, we study the system performance in terms of data detection mean squared error and bit error rate, and show that the proposed method provides excellent performance at low computational cost. Such advantages are of paramount importance for practical implementation of high data rate acoustic OFDM systems.

Offset-Free Proportional-Type Self-Tuning Speed Controller for Permanent Magnet Synchronous Motors

Abstract: This paper exhibits a robust speed controller equipped with a self-tuner for permanent magnet synchronous motors (PMSMs), taking nonlinearity and model-plant mismatches into account. The first contribution of the proposed technique is designing a self-tuner for updating the cutoff frequency of target speed dynamics. The second one is rendering the closed-loop system to recover the target tracking performance and remove the offset errors in the absence of integrators. A 5-kW prototype interior PMSM is used to experimentally verify the effectiveness of the proposed technique.

Carrier frequency offsets estimation in UWA-OFDM communication systems using Zadoff-Chu sequences

Abstract: Frequency offset estimation is an important module in the synchronisation of underwater acoustic (UWA) orthogonal frequency division multiplexing (OFDM) systems. Different ways are used for carrier frequency offset (CFO) estimation such as maximum likelihood based on a cyclic prefix. In this paper, the Zadoff-Chu (ZC) sequences are used for OFDM synchronisation in underwater communications. The normalised carrier frequency offset can be estimated using the ZC cross-correlation between the primary synchronisation signal and the corresponding local signal, which causes large complexity. The ZC sequences have a time centre symmetric property, and thus the autocorrelation of the received primary synchronisation signal can be used for frequency offset estimation. In this paper, we propose a modified algorithm with low complexity for frequency offset estimation. Simulation results demonstrate that the proposed algorithm can estimate the frequency offset accurately with simple implementation in compariso...

Joint inversion methods with relative density offset correction for muon tomography and gravity data, with application to volcano imaging

Abstract: Muography is a relatively new geophysical imaging method that uses muons to provide estimates of average densities along particular lines of sight. Muography can only see above the horizontal elevation of the detector and it is therefore attractive to attempt a joint inversion of muography data with gravity data, which is also responsive to density but generally requires combination with another geophysical data set to overcome issues related to non-uniqueness and poor depth resolution. Some previous work has investigated this joint inverse problem and demonstrated the potential improvements to be gained by jointly inverting muography and gravity data. However, there has yet to be a thorough investigation of different numerical approaches for formulating the joint inverse problem. Particularly important is how to account for the fact that even though the two data types are sensitive to the same physical quantity, density, they respond through different response functions. Moreover, the two measurements are affected by different systematic uncertainties that are difficult to model. In this work, we considered an approximation where the two density quantities, inferred from the two data types, can be related by an unknown scalar offset. We considered various existing and new joint inversion methods that might solve this problem and we applied them to a synthetic volcano imaging scenario based on the Puy de Dome volcano in the Central Massif region of France. We used unstructured meshes in our modelling to adequately honour the significant topography in that scenario. Our experiments indicated that the most successful joint inversion method for this type of geological scenario was one in which the data misfit function is reformulated to automatically determine the best-fitting offset following a least-squares minimization argument. However, other approaches showed merit and we suggest several of the investigated methods be applied and compared for any specific joint inversion scenario.

Analysis of SRAM Enhancements Through Sense Amplifier Capacitive Offset Correction and Replica Self-Timing

Abstract: An analysis of timing and input-referred offset of sense amplifiers (SA) is presented, and a new SA architecture with capacitive offset correction is proposed. Offset sources are first analyzed in a cross-coupled latch-based SA design, and the analysis is then extended to the proposed SA. The results show the proposed offset correction technique can reduce the total sensing time by up to 40%, while eliminating dynamic offset due to the difference in resolving inverters trip points. A self-timed SRAM with a new replica timing structure is designed to generate optimal SA enable timing with respect to the total input-referred offset. Calculations for timing delay and offset are compared with simulation results in both a conventional and a proposed SA design. The presented simulation results are based on a 10 Kb CMOS SRAM array in 130 nm BiCMOS SiGe technology operating at a 500 MHz clock and 1.5 V supply.

Output offset in silicon Hall effect based magnetic field sensors

Abstract: In this paper we present simulation and measurements for output offset in integrated silicon Hall sensors. Using FEM simulations of various sensor structures, sources of output offset and methods to mitigate this are identified. The simulation results indicate that using cross-shaped sensors exhibit 75% higher variance than octagon shaped sensors as well as sensors shaped as a square with rounded corners. It is determined that restricting the direct current flow path would yield larger offset variances. Additionally the measurements indicate that there are proximity effects that also impact the offset in addition to the geometry. Sensors surrounded by other structures do exhibit the variation relations observed in the simulations. The sensors located on the edges exhibit additional sensor offset variation. The measured sensor offsets vary between 5 mV–20 mV including proximity effects. If we can reduce proximity effects the variation is measured from 5 mV to 10 mV. Therefore reducing the Hall sensor output voltage offset variance involves using dummy devices as avoidance of restrictions on the current flow.

Investigation of k-ε Turbulent Models and Their Effects on Offset Jet Flow Simulation

Abstract: In the case in which relatively low thickness and high-velocity flow enter into the lower velocity fluid, the resulting interference field of these two flows is called the jet. This phenomenon is the dominant output of power plants and some of the dams. The jets can be divided into two categories of free jets and confined jets, caused by the distance from the discharge to limited boundaries points. The offset jet is a type of confined jet in which both free surface and wall boundaries are near the diffusion location. The jet flow due to the extreme curvature in the main flow path and the proximal portion of this flow with solid boundaries have characteristics that make it difficult to solve with simple turbulence models. In this research, the offset jet phenomenon and related issues have been investigated. For this purpose, the offset jet flow pattern and probable factors in the complexity of this model have been simulated using Fluent software which analyses fluid flow in a two dimensional and three dimensional finite volume method. The simulation of offset jet flow pattern has been performed with a focus on investigating different models of turbulence k-e, also boundary conditions, various wall functions and other effective coefficients in the numerical model and the model results compared with test case data findings and validating results, the necessary approaches in numerical simulation of this phenomenon for using in the next stages had been taken.

Kinematics analysis and testing of novel 6-P-RR-R-RR parallel platform with offset RR-joints:

Abstract: This paper presents a novel six-degree-of-freedom (6-DOF) parallel platform that is used as the third mirror adjustment system of a large space telescope. In order to meet the design requirements o...

Offset detection in GPS position time series using multivariate analysis

Abstract: Proper analysis and subsequent interpretation of GPS position time series is an important issue in many geodetic and geophysical applications. The GPS position time series can possibly be contaminated by some abrupt changes, called offsets, which can be well compensated for in the functional model. An appropriate offset detection method requires proper specification of both functional and stochastic models of the series. Ignoring colored noise will degrade the performance of the offset detection algorithm. We first introduce the univariate analysis to identify possible offsets in a single time series. To enhance the detection ability, we then introduce the multivariate analysis, which considers the three coordinate components, north, east and up, simultaneously. To test the performance of the proposed algorithm, we use synthetic daily time series of three coordinate components emulating real GPS time series. They consist of a linear trend, seasonal periodic signals, offsets and white plus colored noise. The average detection power on individual components, either north, east or up, are 32.3 and 47.2% for the cases of white noise only and white plus flicker noise, respectively. The detection power of the multivariate analysis increases to 70.8 and 87.1% for the above two cases. This indicates that ignoring flicker noise, existing in the structure of the time series, leads to lower offset detection performance. It also indicates that the multivariate analysis is more efficient than the univariate analysis for offset detection in the sense that the three coordinate component time series are simultaneously used in the offset detection procedure.

In-vivo validation of interpolation-based phase offset correction in cardiovascular magnetic resonance flow quantification: a multi-vendor, multi-center study

Abstract: A velocity offset error in phase contrast cardiovascular magnetic resonance (CMR) imaging is a known problem in clinical assessment of flow volumes in vessels around the heart. Earlier studies have shown that this offset error is clinically relevant over different systems, and cannot be removed by protocol optimization. Correction methods using phantom measurements are time consuming, and assume reproducibility of the offsets which is not the case for all systems. An alternative previously published solution is to correct the in-vivo data in post-processing, interpolating the velocity offset from stationary tissue within the field-of-view. This study aims to validate this interpolation-based offset correction in-vivo in a multi-vendor, multi-center setup. Data from six 1.5 T CMR systems were evaluated, with two systems from each of the three main vendors. At each system aortic and main pulmonary artery 2D flow studies were acquired during routine clinical or research examinations, with an additional phantom measurement using identical acquisition parameters. To verify the phantom acquisition, a region-of-interest (ROI) at stationary tissue in the thorax wall was placed and compared between in-vivo and phantom measurements. Interpolation-based offset correction was performed on the in-vivo data, after manually excluding regions of spatial wraparound. Correction performance of different spatial orders of interpolation planes was evaluated. A total of 126 flow measurements in 82 subjects were included. At the thorax wall the agreement between in-vivo and phantom was − 0.2 ± 0.6 cm/s. Twenty-eight studies were excluded because of a difference at the thorax wall exceeding 0.6 cm/s from the phantom scan, leaving 98. Before correction, the offset at the vessel as assessed in the phantom was − 0.4 ± 1.5 cm/s, which resulted in a − 5 ± 16% error in cardiac output. The optimal order of the interpolation correction plane was 1st order, except for one system at which a 2nd order plane was required. Application of the interpolation-based correction revealed a remaining offset velocity of 0.1 ± 0.5 cm/s and 0 ± 5% error in cardiac output. This study shows that interpolation-based offset correction reduces the offset with comparable efficacy as phantom measurement phase offset correction, without the time penalty imposed by phantom scans. The study was registered in The Netherlands National Trial Register (NTR) under TC 4865 . Registered 19 September 2014. Retrospectively registered.

Deep Learning-based Frame and Timing Synchronization for End-to-End Communications

Abstract: End-to-end learning-based communications systems are more likely to achieve the global optimal performance. In this work, we implement a complete communications system as an end-to-end deep neural network, including transmitter, channel model, synchronization and receiver. There are a lot of issues which can result to the out of synchronization between the transmitter and the receiver, including sampling timing offset, sampling frequency offset and so on. Therefore, we focus on frame and timing synchronization in the end-to-end learning-based communications systems. Our results show that such an end-to-end learning-based communications system is robust to the impairments that arise from sampling frequency offset. An extra synchronization model based on the convolutional neural networks is introduced to achieve frame synchronization and compensate for the impairments which arise from sampling time offset and sampling time error. The performances of the synchronization model are evaluated from the symbol error rate and the frame header detection results. It can correctly detect most of the actual position of frame header, and it is about 2dB better than that of the direct correlation detection in the end-to-end communications systems.

Data Driven Control: An Offset Free Approach

Abstract: This work presents a data driven control strategy able to track a set point without steady state error. The control sequence is computed as an affine combination of past control signals, which belong to a set of past closed loop trajectories stored in a process historian database. This affine combination is computed so that the variance of the tracking error is minimized. It is shown that offset free control (zero mean tracking error) is achieved under the assumption that the underlying dynamics are linear and the closed loop trajectories of the database are in turn offset free. That is, the proposed strategy inherits the offset free tracking capability of the stored past closed loop trajectories. No prior or subsequent knowledge about the process dynamics is required. The procedure to build the database is to store only the best trajectories that meet a design criteria, chosen from a series of iteratively tuned controllers. In this way the proposed controller will learn how to obtain a well tuned control in spite of the different operating conditions.

Adjustment of Transceiver Lever Arm Offset and Sound Speed Bias for GNSS-Acoustic Positioning

Abstract: Global Navigation Satellite System—Acoustic (GNSS-A) positioning is the main technique for seafloor geodetic positioning. A transceiver lever arm offset and sound velocity bias in seawater are the main systematic errors of the GNSS-A positioning technique. Based on data from a sea trial in shallow water, this paper studies the functional model of GNSS-A positioning. The impact of the two systematic errors on seafloor positioning is analysed and corresponding processing methods are proposed. The results show that the offset in the lever arm measurement should be parameterised in the observation equation. Given the high correlation between the vertical lever arm offset and the vertical coordinate of the seafloor station, a sample search method was introduced to fix the vertical offset correction. If the calibration of the sound velocity profiler cannot be ensured, the correction parameter of the sound velocity bias should be solved. According to the refined functional model and corrections, the position of a seafloor station in shallow water can be determined with a precision of better than 1 cm.

FDA transmit beampattern synthesis using piecewise trigonometric frequency offset

Abstract: The frequency diverse array (FDA) exploits an offset in the transmitted frequency of each array element to generate a beampattern that varies as a function of angle and range. This article proposes a piecewise frequency offset based on a simple trigonometric form. It is shown that the proposed offset offers improved peak-to-sidelobe ratio (PSR) performance and achieves a narrower mainlobe compared to other common frequency offset forms.

Geometric Control of a Quadrotor with a Load Suspended from an Offset

Abstract: A quadrotor with a point-mass payload suspended with an offset from the center-of-mass of the quadrotor to the suspension point is studied in this paper. This system consists of eight degrees of freedom and four degrees of underactuation. A coordinate-free dynamic model is obtained by taking variations on manifolds. We also establish that under a mild assumption that the angular acceleration of quadrotor is small, the offset quadrotor-Ioad system is a differentially-flat system with the load position and the quadrotor yaw serving as the flat outputs. A nonlinear geometric control design based on this assumption is developed. With this controller, the following states (a) quadrotor attitude, (b) load attitude, and (c) load position can be tracked. Stability proofs for the controller design, as well as simulation of the proposed controller are presented. A comparison of a geometric controller developed for a zero offset quadrotor-Ioad model is also presented to motivate the need as well as demonstrate the advantages of our proposed geometric controller for the offset quadrotor-Ioad model.

Offset free data driven control: application to a process control trainer

Abstract: This work presents a data driven control strategy able to track a set point without steady-state error. The control sequence is computed as an affine combination of past control signals, which belong to a set of trajectories stored in a process historian database. This affine combination is computed so that the variance of the tracking error is minimised. It is shown that offset free control, that is zero mean tracking error, is achieved under the assumption that the state is measurable, the underlying dynamics are linear and the trajectories of the database share the same error dynamics and are in turn offset free. The proposed strategy learns the underlying controller stored in the database while maintaining its offset free tracking capability in spite of differences in the reference, disturbances and operating conditions. No training phase is required and newly obtained process data can be easily taken into account. The proposed strategy, related to direct weight optimisation learning techniques, is tested on a process control trainer.

Optimum Full Information, Unlimited Complexity, Invariant, and Minimax Clock Skew and Offset Estimators for IEEE 1588

Abstract: This paper addresses the problem of clock skew and offset estimation (CSOE) for the IEEE 1588 precision time protocol. Built on the classical two-way message exchange scheme, IEEE 1588 is a prominent synchronization protocol for packet switched networks. Due to the presence of random queuing delays in a packet switched network, the joint recovery of clock skew and offset from the received packet timestamps can be viewed as a statistical estimation problem. Recently, assuming perfect clock skew information, minimax optimum clock offset estimators were developed for IEEE 1588. Building on this work, we first develop joint optimum invariant clock skew and offset estimators for IEEE 1588 for known queuing delay statistics and unlimited computational complexity. We then show that the developed estimators are minimax optimum, i.e., these estimators minimize the maximum skew normalized mean square estimation error over all possible values of the unknown parameters. Minimax optimum estimators that utilize information from past timestamps to improve accuracy are also introduced. The developed optimum estimators provide useful fundamental limits for evaluating the performance of CSOE schemes. These performance limits can aid system designers to develop algorithms with the desired computational complexity that achieve performance close to the performance of the optimum estimators. If a designer finds an approach with a complexity they find acceptable and which provides performance close to the optimum performance, they can use it and know they have near optimum performance. This is precisely the approach used in communications when comparing to capacity.

Mitigating the Effects of Track Mis-Registration in Single-Reader/Two-Track Reading BPMR Systems

Abstract: Bit-recording technologies that can provide areal densities (ADs) [patterned magnetic recording (BPMR) is expected to be one of the new magnetic ADs] of 1 Tera-bit per square inch or higher. To achieve these ADs, the space between tracks must be reduced, bringing them closer and closer together, leading to significant inter-track interference (ITI). Track mis-registration (TMR) or head offset can further degrade overall system performance. To mitigate the effects of ITI and TMR, we propose using a single-reader/two-track reading (SRTR) scheme together with an over-sampling technique on a staggered BPMR system. We also propose a TMR estimation technique based on a readback signal. Here, the readback signal is separated into two sequences, one odd and one even. Then, the energy ratio is calculated using these data sequences. The obtained relationship between the energy ratio and head offset can be utilized to predict the actual head offset occurrence in the reading process. Finally, a pairing of a monic constraint target and an equalizer that accordingly matches each estimated head offset level is adopted to deal with the TMR effect. The SRTR system can provide better bit-error-rate (BER) performance. Moreover, when TMR effects appear in the reading process, our proposed SRTR system with a TMR mitigation technique can yield better BER performance, especially at high head offset levels.

Wireless communications using traffic information

Abstract: Systems, apparatuses, and methods are described for wireless communications. A base station may determine configuration parameters for a wireless device. The configuration parameters may be based on traffic pattern information received from the wireless device, such as a traffic periodicity, a timing offset, and/or a message size.

DEM investigation of the power draw for material movement in rotary drums with axis offset

Abstract: The power draw for material movement is an important design parameter for the motor/drive train of industrial rotary drum systems. It is also the valuable process information reflecting working conditions of the drum. Most power draw calculation methods assume that the particles are mono-sized or evenly distributed, and the drum has no axis offset. However, these assumptions may not be always satisfied. In the present work, the power draw for material movement in a rotary drum filled with multi-dispersed particles is investigated using an experimentally validated DEM model. The effects of axis offset, rotational speed and filling degree of the drum are studied. Discrete Fourier Transform is performed to capture features of the simulated power draw profile. It is found that periodicity of the power draw profile is caused by axis offset of the drum, and its frequency is equal to the rotational frequency of the drum. Regression analysis shows that the peak and mean of the power draw is proportional to rotational speed and filling degree. The axis offset of the drum has no significant influence on the mean power draw, but it determines greatly the overshoot. Result of the work contributes to a better understanding of the power draw from microscopic and macroscopic view. It has potential usage for online monitoring of the axis offset of industrial rotary drums to prevent motor damage.