Noise Equivalent Research Articles

Assessment of UAV-Onboard Multispectral Sensor for Non-Destructive Site-Specific Rapeseed Crop Phenotype Variable at Different Phenological Stages and Resolutions

Unmanned aerial vehicles (UAVs) equipped with spectral sensors have become useful in the fast and non-destructive assessment of crop growth, endurance and resource dynamics. This study is intended to inspect the capabilities of UAV-onboard multispectral sensors for non-destructive phenotype variables, including leaf area index (LAI), leaf mass per area (LMA) and specific leaf area (SLA) of rapeseed oil at different growth stages. In addition, the raw image data with high ground resolution (20 cm) were resampled to 30, 50 and 100 cm to determine the influence of resolution on the estimation of phenotype variables by using vegetation indices (VIs). Quadratic polynomial regression was applied to the quantitative analysis at different resolutions and growth stages. The coefficient of determination (R2) and root mean square error results indicated the significant accuracy of the LAI estimation, wherein the highest R2 values were attained by RVI = 0.93 and MTVI2 = 0.89 at the elongation stage. The noise equivalent of sensitivity and uncertainty analyses at the different growth stages accounted for the sensitivity of VIs, which revealed the optimal VIs of RVI, MTVI2 and MSAVI in the LAI estimation. LMA and SLA, which showed significant accuracies at (R2 = 0.85, 0.81) and (R2 = 0.85, 0.71), were estimated on the basis of the predicted leaf dry weight and LAI at the elongation and flowering stages, respectively. No significant variations were observed in the measured regression coefficients using different resolution images. Results demonstrated the significant potential of UAV-onboard multispectral sensor and empirical method for the non-destructive retrieval of crop canopy variables.

Uncooled CMOS Integrated Triple-Band Terahertz Thermal Detector Comprising of Metamaterial Absorber and PTAT Sensor

This paper presents an uncooled monolithic resonant triple-band terahertz (THz) thermal detector using a 55 nm complementary metal oxide semiconductor (CMOS) process. The novel integration of a compact triple-band metamaterial (MM) absorber coupled with a sensitive proportional to absolute temperature (PTAT) sensor leads to a compact, uncooled, cost-effective, easy-integration, and mass-production CMOS integrated triple-band THz thermal detector. The principles of operation and physical modeling such as selective absorption of electromagnetic energy, thermal energy conversion, and electrical response are demonstrated. The triple-band MM absorber achieves high absorption magnitudes of 90.4%, 96.8%, and 98.8% at 0.91, 2.58, and 4.3 THz respectively. The optimized PTAT sensor shows a high temperature coefficient of voltage of 10.11 mV/°C. Simulated responsivities are 37.28 V/W at 0.91 THz, 49.9 V/W at 2.58 THz, and 61.11 V/W at 4.3 THz. The proposed triple-band THz thermal detector shows calculated noise equivalence powers (NEPs) of 1.07, 1.6, and 1.31 μW/Hz 0.5 at 0.91, 2.58, and 4.3 THz respectively. Relatively better experimental results are obtained at 0.91 THz and 2.58 THz due to the scarcity of THz sources. The proposed detector achieves maximum responsivities of 33.4 V/W and 47.9 V/W, while minimum NEPs of 1.49 μW/Hz 0.5 at 0.91 THz with a modulation frequency of 2 Hz, and 1.88 μW/Hz 0.5 at 2.58 THz with a modulation frequency of 0.5 Hz.

Resonant Polysilicon Antenna for Terahertz Detection

Resonant antennas have garnered considerable interest in terahertz and visible regimes owing to its extraordinary localized field concentration capability. In this work, we experimentally demonstrate a novel metal-free terahertz detector, which is fashioned by heavily doped polysilicon using standard CMOS process. The computational results show that the incident field can be largely enhanced within the antenna gap area at the resonance of 650 GHz. The room temperature measured results show that the responsivity and noise equivalence power of the detector integrated with the optimized antenna design is 600 V/W and 200 pW/Hz0.5 at 650 GHz, respectively. Aided by an equivalent circuit model, theoretical analysis is carried out to elucidate that the field enhancement ratio of the resonant polysilicon antenna is comparable to gold made antenna at terahertz frequencies. Our study provides a new approach for designing a low-cost and CMOS-compatible terahertz detector characterized with strongly localized field, projecting more insights on light-matter interaction at terahertz frequencies.

Dual-frequency CMOS terahertz detector with silicon-based plasmonic antenna.

Multi-frequency Terahertz (THz) detectors have shown great application potentials in THz imaging and sensing systems. For the first time to our knowledge, a novel dual-frequency THz detector with the stacked structure consisting of a silicon-based plasmonic antenna and a metal-based antenna in one compact unit is proposed and fabricated in standard CMOS technology. Compared with the metal antenna, the antenna based on heavy-doped poly-silicon materials enables the detector to excite localized surface plasmon resonance mode, making the effective absorption of the THz waves and thus resulting in the significant responsivity enhancement of the detector. The experimental results show a maximum voltage responsivity up to about 2000 V/W and 450 V/W, while the noise equivalence power is as low as 23 pW/Hz0.5 and 110 pW/Hz0.5 for the silicon antenna and metal antenna at the frequency of 220 GHz and 650 GHz, respectively. The presented dual-frequency detector can be easily implemented in a small size in favor of high-density array integration.

Integrated polychromator and data acquisition system for the Thomson scattering diagnostic

New experiments with higher electron temperatures in the gas dynamic trap (GDT) magnetic mirror require a substantial upgrade of the Thomson scattering diagnostic. The paper presents the recently developed polychromator based on interference filters, which has the data acquisition and processing system onboard. The six spectral channels have wavelength pass bands distributed from 900 nm to 1057 nm to enable measurements of the electron temperature in the range from 20 eV to approximately 2 keV . The optimized design of the detection module with the avalanche photodiode and the signal amplifier yields the transmission factor of 4× 106 V/W in the bandwidth of 1 to 50 MHz in the high-speed detection channel. For a 1064 nm laser pulse of 10 ns duration, the amplifier noise equivalent is only 30 photons. Every detection module is also equipped with the low-speed (0 to 1 kHz) detection channel for separate measurements of background plasma radiation. This option also enables an easy calibration of the spectral response function using a continuous-wave light source like tungsten lamp. The high-speed acquisition channel utilizes the “time stretch” principle. It uses the 5.5 GSample/s analog memory arranged in the switched capacitor array to hold the signal trace of 200 ns duration, which is then processed by a relatively slow 14-bit digitizer. The acquisition and readout sequence can be cycled at the frequency of up to 40 kHz providing the necessary time resolution in experiments with multiple laser beam pulses. The polychromator onboard data processing electronics is controlled by the System on Chip solution with the procedures of data processing implemented in the Field Programmable Gate Array. Lab test results along with first plasma measurements are presented in the paper.

Local asymptotic equivalence of pure states ensembles and quantum Gaussian white noise

Quantum technology is increasingly relying on specialised statistical inference methods for analysing quantum measurement data. This motivates the development of “quantum statistics”, a field that is shaping up at the overlap of quantum physics and “classical” statistics. One of the less investigated topics to date is that of statistical inference for infinite dimensional quantum systems, which can be seen as quantum counterpart of nonparametric statistics. In this paper, we analyse the asymptotic theory of quantum statistical models consisting of ensembles of quantum systems which are identically prepared in a pure state. In the limit of large ensembles, we establish the local asymptotic equivalence (LAE) of this i.i.d. model to a quantum Gaussian white noise model. We use the LAE result in order to establish minimax rates for the estimation of pure states belonging to Hermite–Sobolev classes of wave functions. Moreover, for quadratic functional estimation of the same states we note an elbow effect in the rates, whereas for testing a pure state a sharp parametric rate is attained over the nonparametric Hermite–Sobolev class.

Modulation transfer function measurements of Type-II mid- wavelength and long-wavelength infrared superlattice focal plane arrays

Mid-wavelength Infrared (MWIR) and long-wavelength infrared (LWIR) Barrier Infrared Detector (BIRD) based on Antimonides Type-II superlattice detector array material are hybridized to 640 × 512, 1024 × 1024 and 1344 × 784 pixels format read out integrated circuits. The focal plane arrays (FPAs) Noise Equivalent Temperature Difference (NEΔT), Quantum Efficiency (η), Dark Current Density (JD), and Modulation Transfer Function (MTF) performance were measured at operating temperatures. High performance 640 × 512 array format MWIR High Operating Temperature (HOT) FPA has typical NEΔT ∼ 19 mK, JD ∼ 6.2 × 10−7 A/cm2, and η ∼ 53% using 3–5 μm band pass filter at 115 K operating temperatures. Best performance 640 × 512 array format LWIR FPA has NEΔT ∼ 25 mK, JD ∼ 2.5 × 10−5 A/cm2 and η ∼ 41% using 8–9.4 μm band pass filter at 60 K operating temperatures. For MTF investigation, a novel direct one-to-one image approach of Line Spread Function (LSF) and Edge Spread Function (ESF) are patterned onto substrate-removed FPAs. The direct LSF and ESF image are produced by 1000 A° thick gold layer deposition. The direct image horizontal and vertical MTFs are compared with projected knife-edge ESF-derived MTFs and results indicate that direct image MTFs have higher values compared to projected knife-edge ESF-derived MTFs at a Nyquist frequency. However, direct image MTF requires no lens MTF correction. The only relevant requirement for the direct image MTF is for the deposited pattern and substrate to be extremely thinned in which the HOT-BIRD FPAs fulfilled for this investigation.

LWIR QWIPs at IRnova for next generation polarimetric imaging

Polarization sensitive quantum well infrared photodetector (QWIP) focal plane arrays (FPAs) with 30 and 15 µm pitch sizes are fabricated with wire grid polarizers monolithically integrated on the pixels. High polarization contrast is achieved for pixels with 30 µm pitch size, 0.58 ± 0.05 depending on the grating orientation, with good spatial homogeneity (standard deviation below 0.01). The polarization contrast drops to 0.30 ± 0.05 for 15 µm pixel pitch. Influence of the grating orientation on the optical responsivity and the polarization contrast has been evaluated showing the strongest impact for +45° orientations. The fabricated FPAs exhibit temporal and spatial Noise Equivalent (NE) Degree of Linear Polarization (DoLP) of 0.03% and 0.23%, respectively, setting the resolution limit of DoLP to 0.4%. Capability of the fabricated FPAs to image polarimetric signatures in the dynamic scenes with high frame rate has been demonstrated.

Assessment of the High Resolution SAR Mode of the RADARSAT Constellation Mission for First Year Ice and Multiyear Ice Characterization

Simulated compact polarimetry from the RADARSAT Constellation Mission (RCM) is evaluated for sea ice classification. Compared to previous studies that evaluated the potential of RCM for sea ice classification, this study focuses on the High Resolution (HR) Synthetic Aperture Radar (SAR) mode of the RCM associated with a higher noise floor (Noise Equivalent Sigma Zero of −19 dB), which can prove challenging for sea ice monitoring. Twenty three Compact Polarimetric (CP) parameters were derived and analyzed for the discrimination between first year ice (FYI) and multiyear ice (MYI). The results of the RCM HR mode are compared with those previously obtained for other RCM SAR modes for possible CP consistency parameters in sea ice classification under different noise floors, spatial resolutions, and radar incidence angles. Finally, effective CP parameters were identified and used for the classification of FYI and MYI using the Random Forest (RF) classification algorithm. This study indicates that, despite the expected high noise floor of the RCM HR mode, CP SAR data from this mode are promising for the classification of FYI and MYI in dry ice winter conditions. The overall classification accuracies of CP SAR data over two test sites (96.13% and 96.84%) were found to be comparable to the accuracies obtained using Full Polarimetric (FP) SAR data (98.99% and 99.20%).

Comb-Assisted Cavity Ring Down Spectroscopy of 17O enriched water between 6667 and 7443 cm−1

The room temperature absorption spectrum of water vapour highly enriched in 17O is studied by Comb Assisted-Cavity Ring Down Spectroscopy (CA-CRDS) near 1.4 µm. The investigated spectral region (6667–7443 cm−1) is a strong absorbing region corresponding to the first hexade of interacting vibrational states. As a consequence of the high sensitivity of the recordings (Noise Equivalent Absorption, αmin∼ 10−10 cm−1), a series of spectra could be recorded at very low pressure (less than 0.1 Torr) allowing for accurate determination of line centres and the spectral resolution of highly blended multiplets. For instance, 85 lines of the main isotopologue located near much stronger lines are measured for the first time.The assignments were performed using known experimental energy levels as well as calculated line lists based on the results of Schwenke and Partridge. Overall, the experimental list includes 9144 water lines which were assigned to 9988 transitions of six isotopologues (H216O, H217O, H218O, HD16O, HD17O and HD18O). Their intensities span six orders of magnitude from 10−27 to 10−21 cm/molecule at 296 K.Most of the new results concern the H217O isotopologue: more than 2300 new lines were measured, 64 new levels were determined and seven levels were corrected. In the case of HD17O, 152 new transitions were assigned and ten levels were newly determined. The center values of non-blended lines are reported with an accuracy better than 3 MHz (10−4 cm−1) which represents an improvement compared to previous determinations. The comparison to the water vapor line list provided by the recently released 2016 version of the HITRAN database reveals a number of issues.

A statistical model for DPA when algorithmic noise is dependent on target

AbstractIn side‐channel attacks, information about any intermediate data except the target data will be considered as noise, namely, the “algorithmic noise.” Algorithmic noise is always assumed to be independent of the target data. As a result, it is thought to be an equivalence of physical noise. Numerous investigations are built on this intuitive assumption. In this paper, we claim that this assumption is not always true and find the algorithm (e.g., SIMON) for which the algorithmic noise is dependent on the target data. On this condition, we reconsider the issue of success rate estimation and build a modified statistical model to accurately estimate the success rate when the algorithmic noise is dependent on the target data. Finally, experimental results for SIMON algorithm validate the soundness of our methodology. It is also worth mentioning that SIMON is a candidate proposed by the National Security Agency as the standard light‐weight block cipher. Copyright © 2016 John Wiley & Sons, Ltd.

Fly the electric skies

IF YOU FLY ONE OF TODAY'S SMALL piston-powered planes, you will burn many gallons of fuel per hour and suffer through the noise equivalent of a ride on a power mower. But unlike what you face while cutting your grass, if the engine quits, it means an immediate emergency landing at best and a crash at worst. Fortunately, it's now possible to envision replacing those noisy gas guzzlers of the sky with electric airplanes, which would be considerably quieter, cleaner, safer, and more efficient than today's aircraft. Indeed, electrification could transform the current small-airplane experience into something vastly more attractive to both pilots and the communities over which they fly.

Evaluating chlorophyll density in winter oilseed rape (Brassica napus L.) using canopy hyperspectral red-edge parameters

Accurate assessments of chlorophyll density (ChD) using hyperspectral techniques are important for effective evaluation of plant productivity and precise nitrogen (N) management in winter oilseed rape. To develop a quantitative estimation model for determining ChD in winter oilseed rape, field experiments with different N fertilizer levels were conducted over two successive years by measuring canopy hyperspectral reflectance and ChD at various developmental stages. The relationships between two types of parameters (existing red-edge spectral parameters and newly-developed red-edge area parameters) and ChD were investigated to determine the optimal red-edge spectral parameters (ORSPs) for ChD predictions. The Noise Equivalent (NE) model was adopted to evaluate the sensitivity and accuracy of the ORSPs for detecting changes in ChD across different growth stages. The results indicated that canopy hyperspectral reflectance and its first derivative spectra significantly varied with the levels of N fertilization. A strong correlation also existed between canopy reflectance data and ChD. Using a training dataset, the best results for assessing ChD status were observed when using the newly-developed red-edge area parameter, which indicated a difference between the double-peak areas based on the position of the main peak (DIDRmid). DIDRmid was the ORSP and exhibited a significant exponential relationship with ChD, with a coefficient of determination (R2) of 0.88 and a standard error (SE) of 0.312. Tests conducted on the independent validation dataset showed that DIDRmid can be used to accurately predict ChD in oilseed rape, with a relative root mean square error (RRMSE) of 0.091 and a mean relative error (MRE) of 7.22%. Additionally, this ORSP also had relatively lower NE values and higher sensitivity and accuracy with respect to ChD estimation. Consequently, the ChD of winter oilseed rape can be stably estimated with the hyperspectral red-edge methods established in this study because the newly-developed red-edge area spectral parameter was effective and accurate in evaluating ChD.

Imaging Applications of Noise Equivalent Quanta

Imaging Applications of Noise Equivalent Quanta

An Efficient Assessment Methodology for the Diagnosis of Neurological Disorders from the Uttered Speech Signal

Automatic regular monitoring of the people with speech dysfunctions and the identification of the diseases has a considerable effect in the civilization. Recent days, researches are going on to find the correlation between the speech dysfunctions and the speech impairments. Many algorithms are there to forecast the sternness of the dysfunction's signs. The dysfunctions are majorly classified into Dysarthria & Apraxia. The goal of this paper is to diagnose the people who are affected by the Dysarthria and Apraxia, the diseases under the category taken into account here are Parkinson's disease, Cerebral Palsy, Aphasia and Throat tumor. The total survey on the voice signals of the subjects was made and the dysponia attributes namely Jitter, Shimmer, Pitch, Entropy, Glottal to Noise Equivalent Ratio, Harmonics to Noise Ratio and Wavelet based Dynamic Mel Frequency Coefficients have been extracted from the recorded speech signals using their respective algorithms. Besides this, the categorization has been done using the Eigen value based Support Vector Machine (SVM) classifier to sort out the subjects. The proposed algorithm attained 97.83% accuracy. We visualize our work as the improvement headed for the advancement of acoustic signal processing for the automated unremitting scrutinizes.

광역관측을 위한 영상레이더 TOPS 모드 설계 기법

In this paper, the design technique of the wide swath TOPS(Terrain Observation by Progressive Scan) imaging mode is introduced. The TOPS mode overcomes the scalloping limitations imposed by ScanSAR mode by steering the antenna pattern along track direction during the acquisition of a burst. This paper reports the operation concept of TOPS imaging and mode design result to extract the SAR operational parameters. Finally, several analyzed results such as IRF(Impulse Response Function), NESZ(Noise Equivalent Sigma Zero) and DTAR(Distributed Target Ambiguity Ratio) are presented.

Equivalence of time and aperture domain additive noise in ultrasound coherence.

Ultrasonic echoes backscattered from diffuse media, recorded by an array transducer and appropriately focused, demonstrate coherence predicted by the van Cittert-Zernike theorem. Additive noise signals from off-axis scattering, reverberation, phase aberration, and electronic (thermal) noise can all superimpose incoherent or partially coherent signals onto the recorded echoes, altering the measured coherence. An expression is derived to describe the effect of uncorrelated random channel noise in terms of the noise-to-signal ratio. Equivalent descriptions are made in the aperture dimension to describe uncorrelated magnitude and phase apodizations of the array. Binary apodization is specifically described as an example of magnitude apodization and adjustments are presented to minimize the artifacts caused by finite signal length. The effects of additive noise are explored in short-lag spatial coherence imaging, an image formation technique that integrates the calculated coherence curve of acquired signals up to a small fraction of the array length for each lateral and axial location. A derivation of the expected contrast as a function of noise-to-signal ratio is provided and validation is performed in simulation.

65-nm CMOS 300 GHz 영상 검출기 및 영상 획득

본 논문에서는 65-nm CMOS 공정을 이용하여 300 GHz 주파수 대역의 영상 검출기를 제작하고, 이에 기반하여 영상을 획득하였다. 검출기 회로 구조는 square-law 동작에 기초를 두고 있다. 제작된 검출기는 285 GHz에서 2,270 V/W의 최대 반응도(responsivity)와 <TEX>$38pW/Hz^{1/2}$</TEX>의 최소 NEP(Noise Equivalent Power)를 보였으며, 250~305 GHz의 범위에서 NEP< <TEX>${\sim}200pW/Hz^{1/2}$</TEX>를 보였다. 측정용 패드와 밸룬(Balun)을 포함한 제작된 칩의 크기는 <TEX>$400{\mu}m{\times}450{\mu}m$</TEX>이며, 측정용 요소들을 제외한 주요 칩의 크기는 <TEX>$150{\mu}m{\times}100{\mu}m$</TEX>이다. In this work, a 300 GHz imaging detector has been developed and image has been acquired in a 65-nm CMOS technology. The circuit was designed based on the square-law of MOSFET devices. The fabricated detector exhibits a maximum responsivity of 2,270 V/W and minimum NEP of <TEX>$38pW/Hz^{1/2}$</TEX> at 285 GHz, and NEP< <TEX>${\sim}200pW/Hz^{1/2}$</TEX> for 250~305 GHz range. The chip size is <TEX>$400{\mu}m{\times}450{\mu}m$</TEX> including the probing pads and a balun, while the core of the circuit occupies only <TEX>$150{\mu}m{\times}100{\mu}m$</TEX>.

Scatter Fraction, Count Rates, and Noise Equivalent Count Rate of a Single-Bed Position RPC TOF-PET System Assessed by Simulations Following the NEMA NU2-2001 Standards

Scatter Fraction (SF) and Noise Equivalent Count Rate (NECR) of a 2400 mm wide axial field-of-view Positron Emission Tomography (PET) system based on Resistive Plate Chamber (RPC) detectors with 300 ps Time Of Flight (TOF) resolution were studied by simulation using Geant4. The study followed the NEMA NU2-2001 standards, using the standard 700 mm long phantom and an axially extended one with 1800 mm, modeling the foreseeable use of this PET system. Data was processed based on the actual RPC readout, which requires a $0.2~\mu\hbox{s}$ non-paralyzable dead time for timing signals and a paralyzable dead time ( ${\tau_{ps}}$ ) for position signals. For NECR, the best coincidence trigger consisted of a multiple time window coincidence sorter retaining single coincidence pairs (involving only two photons) and all possible coincidence pairs obtained from Multiple coincidences, keeping only those for which the direct TOF-reconstructed point falls inside a tight region surrounding the phantom. For the 700 mm phantom, the SF was 51.8% and, with ${\tau_{ps}} = 3.0~\mu\hbox{s}$ , the peak NECR was 167 kcps at $7.6~\hbox{kBq/cm}^{3}$ . Using ${\tau _{ps}} = 1.0~\mu\hbox{s}$ the NECR was 349 kcps at $7.6~\hbox{kBq/cm}^{3}$ , and no peak was found. For the 1800 mm phantom, the SF was slightly higher, and the NECR curves were identical to those obtained with the standard phantom, but shifted to lower activity concentrations. Although the higher SF, the values obtained for NECR allow concluding that the proposed scanner is expected to outperform current commercial PET systems.

The relative discomfort of noise and vibration: effects of stimulus duration

How noise discomfort and vibration discomfort depend on duration has not previously been compared. For five durations (2, 4, 8, 16 and 32 s), the subjective equivalence of noise and vibration was investigated with all 49 combinations of 7 levels of noise and 7 magnitudes of whole-body vertical vibration. The rates of increase in discomfort with increasing duration were similar for noise and vibration, whereas they are currently assumed to be 3 dB per doubling of noise duration and 1.5 dB per doubling of vibration duration. The discomfort caused by low levels of noise was masked by high magnitudes of vibration, and the discomfort caused by low magnitudes of vibration was masked by high levels of noise. As stimuli durations increased from 2 to 32 s, the influence of vibration on the judgement of noise discomfort decreased, whereas the influence of noise on the judgement of vibration discomfort was unchanged.