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In this paper, we present and evaluate a calibration-free mobile eye-traking system. The system's mobile device consists of three cameras: an IR eye camera, an RGB eye camera, and a front-scene RGB camera. The three cameras build a reliable corneal imaging system that is used to estimate the user's point of gaze continuously and reliably. The system auto-calibrates the device unobtrusively. Since the user is not required to follow any special instructions to calibrate the system, they can simply put on the eye tracker and start moving around using it. Deep learning algorithms together with 3D geometric computations were used to auto-calibrate the system per user. Once the model is built, a point-to-point transformation from the eye camera to the front camera is computed automatically by matching corneal and scene images, which allows the gaze point in the scene image to be estimated. The system was evaluated by users in real-life scenarios, indoors and outdoors. The average gaze error was 1.6∘ indoors and 1.69∘ outdoors, which is considered very good compared to state-of-the-art approaches. [ABSTRACT FROM AUTHOR]

This article presents a fully-integrated Ku-band CMOS down-converter for the low earth orbit satellite user downlink applications. To receive satellite signals adequately, a wideband receiver is presented with an automatic in-phase and quadrature (I/Q) mismatch calibration to carry out above 40 dB image rejection ratio (IRR) to the interferences within 2 GHz span concurrently. During the I/Q signal phase adjustment, the proposed wideband I/Q interpolator (IQI) exhibits almost a constant group delay over the wide IF signal bandwidth, which alleviates the iterative calibration between multiple frequency points in a wideband system. Also, the proposed wideband IQI has apparently less influence on signal amplitude than the reported phase interpolator and delay cell while calibrating I/Q phase imbalance. This work utilizes polyphase filters to fulfill on-chip image-rejection integration and exploits logarithmic power detector to realize I/Q mismatch indication in automatic calibration. The receiver delivers a peak measured conversion gain of 37.8 dB, an averaged noise figure of 6 dB, and below ±1.5 dB gain variation within the full signal band. Above all, the down-converter achieves not only high IRR performance but broad bandwidth at the IF frequencies from 0.3 to 2.35 GHz (48–55 dB IRR, 150% fractional IF bandwidth) without any external control, tuning, or assistance. The closest frequency proximity is no more than 0.6 GHz between the received satellite signal and image. To the best of authors’ knowledge, this work demonstrates the highest fractional IF bandwidth among the reported wideband CMOS receivers with high image rejection (IRR > 40 dB).

A laser total station (LTS) is an environmentally stable position and attitude measurement device that has significant potential for identifying the position and attitude of the roadheader in real-time under severe working conditions. A fast and accurate calibration method of the LTS after the station movement is required for the roadheader attitude auto measurement in real-time. Based on the measurement principle of the laser measurement system, we analyze the mathematical model of the auto-calibration coordinate calculation; then, we establish a calibration error evaluation method for the auto-calibration system. To solve the real-time calibration of the LTS's coordinates, we present an extended Kalman filter algorithm based on the real-time observations and estimations of the coordinates and position. The presented algorithm is verified by a Matlab simulation and a roadheader calibration experiment. [ABSTRACT FROM AUTHOR]

A non-intrusive intelligent monitoring method for elevater state was established. In this method, the acceleration signal is initialized by Weiszfeld algorithm, and the acceleration signal is decomposed into vertical component and horizontal component. The dynamic characteristics of elevator are estimated by Kalman filter. The vibration analysis of horizontal component is carried out and the baseline of normal operation is established. The sensor is calibrated automatically according to the operation characteristics of elevator. According to the unscented Kalman filter fused with simultaneous localization and mapping (SLAM), the sensor information is coupled to track the real-time position of elevator. The effectiveness and robustness of the method were verified in actual operation. The problem of position error accumulation was basically solved without the installation of beacon. This method has low cost and strong universality, and has certain practical significance for promoting the on-demand maintenance of elevator.

Flow simulation and forecasting accuracy using rainfall-runoff models is one of the main challenges in hydrological modelling, especially when focused on the flow simulation at a short time scale. These uncertainties are typically dependent on the model design, the technique used for estimating model parameters, the process of considering rainfall variability and errors in the discharge data used for the calibration. Indeed, the uncertainty associated with the discharge derived from the rating curve is ignored in many earlier rainfall-runoff models. In this paper, we provide a quantitative approach to rigorously investigate the effect that the rating curve uncertainty model has on the auto-calibration of Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS) model at hourly time scale. The multisegment BaRatin rating curve, based on the Bayesian analysis, was used to construct the most probable (MaxPost) rating curve with the bounds uncertainty for hydrometric station of Allala watershed. This allows establishing a new discharge hydrograph with its uncertainty bounds that are subsequently used in HEC-HMS calibration, to provide model parameters with confidence interval and to evaluate the model prediction accuracy. In HEC-HMS model, soil conservation service-curve number (SCS-CN) was applied to compute the runoff losses, while the SCS unit hydrograph (SCS-UH) method was used to estimate the direct runoff at the basin outlet. The model calibration process was carried out for the flood event of 2002 using four objective functions and validated for three independent events. We found that the calibration of the initial abstraction values (IA) varied between −15.16% and 20% when assessing the uncertainties associated with the rating curve, whereas the calibrated curve number values (CN) varied between −5.18% and 7.8%. The confidence interval for the CN and IA were extended from 65.71 to 74.81 and from 26.95 to 19.08, respectively. Results highlighted that the rating curve uncertainty has significant impact on the HEC-HMS model calibration parameters. Rigorous consideration of this uncertainty can improve considerably the model ability to predict the hourly discharge hydrographs. [ABSTRACT FROM AUTHOR]

In this paper, we describe an automatic calibration method and test results for a tile-type subarray consisting of a Tx phased-array antenna for Ku-band satellite communication. For array antenna calibration, the aperture electric field distribution, which is supported by the planar near-field measurement system, is used to minimize the phase variations across the array aperture. All the calibration procedures are performed automatically through interoperation between the planar near-field measurement system and array antenna control board. As conditions for ending the automatic calibration process, the far-field gain, beam width, and pointing direction can be used. The tile-type Tx phased-array antenna used for verification of the proposed method is an 8×8 array of microstrip patch antennas operating in the Ku band and having a phase shifter with 22.5° resolution. [ABSTRACT FROM AUTHOR]

Two search methods are currently available for calibrating the HEC-HMS program: the Univariate Gradient (UG) and the Nelder Mead (NM) methods; both having poor performance in continuous models with snowmelt module. In this paper, a novel approach using Melody Search algorithm (MeS) is presented for auto-calibration of HEC-HMS and compared to Self-adaptive Global Harmony Search (SGHS) and Genetic Algorithms (GA). The results show that the suggested approach is able to overcome the poor performance of aforementioned methods yielding more enhanced solutions. While NM and UG reach a Nash Sutcliffe Index (NSE) of −0.33 and 0.105, GA, SGHS and MeS have been able to reach to 0.526, 0.635, and 0.674 respectively. In addition, the improving power of algorithms was tested by starting from the final solution found by the other methods. It was noticed that in all cases MeS and to some degree SGHS are able to substantially improve the solutions found by either UG or NM. Interestingly, while SGHS was able to slightly improve the solution of MeS algorithm, MeS made a substantial improvement on the solution reached by the SGHS. Finally, the novel MeS based multi-objective algorithm proposed here, i.e. NSMeS, and Non-dominated Sorting Genetic Algorithm-II (NSGA-II) are compared with different combinations of objective functions where NSMeS demonstrated better performance. [ABSTRACT FROM AUTHOR]

This brief describes a high-speed auto-calibrated bit slicer for energy and envelope detection receivers. For robust bit decision, a digital-assisted calibration method with auto threshold estimation and auto phase acquisition is employed. The bit slicer consists of a phase-locked loop for multi-phase clock generation and a dynamic comparator in which the bulk voltage of the input transistor is trimmed for threshold voltage control. The proposed bit slicer is implemented in 65-nm 1P9M CMOS, occupying a total area of 0.07 mm2. Experimental results show that the bit slicer achieves a sensitivity of 6.1 mV at 1 GHz and consumes 1.6 mW from a 1-V supply. [ABSTRACT FROM PUBLISHER]

Heavy vehicles influence general traffic in many different ways compared with passenger vehicles, and this may result in different levels of traffic instability. Increases in the number and proportion of heavy vehicles in the traffic stream will therefore result in different traffic flow conditions. This research initially outlines the different car-following behaviour of drivers in congested heterogeneous traffic conditions indicating the necessity for developing a car-following model, which includes these differences. A psychophysical car-following model, similar in form to Weideman's car-following model, was developed. Due to the complexity of the developed model, the calibration of the model was undertaken using a particle swarm optimisation algorithm with the data recorded under congested traffic conditions. This was then incorporated into a traffic microsimulation model. The results showed that the car-following perceptual thresholds and thus action points of drivers differ based on their vehicle and the lead vehicle types. The inclusion of the heavy vehicles in the model showed significant impacts on the traffic dynamic and interactions amongst different vehicles. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

With enhanced availability of high spatial resolution data, hydrologic models such as the Soil and Water Assessment Tool (SWAT) are increasingly used to investigate effects of management activities and climate change on water availability and quality. The advantages come at a price of greater computational demand and run time. This becomes challenging to model calibration and uncertainty analysis as these routines involve a large number of model runs. For efficient modelling, a cloud-based Calibration and Uncertainty analysis Tool for SWAT (CUT-SWAT) was implemented using Hadoop, an open source cloud platform, and the Generalized Likelihood Uncertainty Estimation method. Test results on an enterprise cloud showed that CUT-SWAT can significantly speedup the calibration and uncertainty analysis processes with a speedup of 21.7–26.6 depending on model complexity and provides a flexible and fault-tolerant model execution environment (it can gracefully and automatically handle partial failure), thus would be an ideal method to solve computational demand problems in hydrological modelling. [ABSTRACT FROM AUTHOR]

This paper presents the design and experimental results of a low-power 300-960 MHz I/Q signal generator for low-IF receivers. The circuit is based on phase-tunable dividers and uses delay-locked loops, which provide phase accuracy for the quadrature signals as well as low-sensitivity of the phase error against temperature and power supply variations. Thanks to the adopted technique, the phase error can be further reduced by trimming the reference voltage of the delay-locked loops through a calibration digital word, which can be stored in a non-volatile memory during manufacturing. The I/Q generator exhibits an absolute phase error before calibration that is lower than 1.5°. The I/Q phase drift due to temperature variations from −40 to 85 °C and power supply variations from 1.1 to 1.3 V is 0.3° and 0.2°, respectively. By dividing the overall frequency range into four 165-MHz wide sub-bands and using only four 5-bit calibration words, the I/Q phase variation with respect to frequency, temperature, and power supply is lower than 1° in the 300-960 MHz operating band. The I/Q generator is implemented in a 90-nm CMOS technology and exhibits a current consumption as low as 0.5 mA. [ABSTRACT FROM AUTHOR]

Highlights: [•] An interface circuit for thick film multi gas sensors is designed and fabricated. [•] The focus is the system for driving the heaters and compensating the effect of the ambient temperature automatically. [•] Accuracy and speed of the system enable each heater to self-calibrate and auto-adjust. [ABSTRACT FROM AUTHOR]

Abstract: An MICS band fractional-N frequency synthesizer using active inductors and auto-calibration technology is presented in this work. The active inductors and capacitors of the loop filter were implemented with MOSFET for decreasing the phase noise and silicon area. Moreover, the proposed auto-calibration technique would reduce and overcome the effect of voltage, temperature, and process variations. This chip was fabricated in 0.18μm CMOS process. The measurement results show that the proposed 402–405 fractional-N PLL occupies a core area of 450×385μm2. The phase noise is −105.5dBc/Hz at 1MHz. The power consumption is 5.13mW at 402MHz. [Copyright &y& Elsevier]

The CMOS transceiver IC exploits the superheterodyne architecture to implement a low-cost RF front-end with an auto-I/Q calibration function for IEEE 802.11g. The transceiver supports I/Q gain and phase mismatch auto tuning mechanisms at both the transmitting and receiving ends, which are able to reduce the phase mismatch to within 1° and gain mismatch to 0.1 dB. Implemented in a 0.25 µm CMOS process with 2.7 V supply voltage, the transceiver delivers a 5.1 dB receiver cascade noise figure, 7 dBm transmit, and a 1 dB compression point. [ABSTRACT FROM AUTHOR]