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Signal-to-noise ratio (SNR) analysis is a crucial component of optical system development for space remote sensing instruments. It serves as a quantitative assessment of the imaging quality and radiometric characteristics of space remote sensing. This paper utilizes the working principles and energy transfer principles of space remote sensing instruments to conduct SNR analysis and model development for commonly used spaceborne imagers, spaceborne imaging spectrometers, micro-optical remote sensing instruments, and point-source spatial targets. Additionally, the paper also examines the impact of the presence and width of slits in different space environments on the SNR of space remote sensing instruments. The calculation results indicate that the analysis of Signal-to-Noise Ratio (SNR) for different space remote sensing instruments requires the establishment of distinct SNR models. The magnitude of SNR primarily depends on crucial factors such as optical system quality, detector performance, and the space environment. Therefore, in the instrument design and data processing processes, it is essential to consider how to maximize SNR and establish more accurate corresponding SNR models to provide high-quality remote sensing data.

An inverse T shape structure, consisting of two perpendicular cavities coupled with a bus-waveguide truncated by a block, has been proposed and investigated numerically. Multi Fano resonance, attributing to the interaction of one continuous and two discrete states, can be observed in transmission spectrum. The numerical results are demonstrated by the coupled mode theory. At the same time, it is feasible to produce multi Fano resonance which derive from the splitting of different order modes by adjusting D value, which has been well explained theoretically. When the inverse T shape is filled with Polyhexamethylene biguanide (PHMB), a perfect absorbing coating to monitor the CO2 concentration, the structure can be served as a high sensitivity CO2 detector, whose sensitivity can up to 303 pm/ppm. In addition, the sensitivity of this proposed structure is ∼2.23 times higher than the previous work. The proposed structure has the advantages of simple, compact and easy fabrication. The results represented in this study may have potential applications in sensing and CO2 detector, which can provide the guideline to design other types of gas detector.

As we look forward to the next generation of hyperspectral infrared (IR) atmospheric sounders, grating spectrometers hold promise for improved performance (e.g., horizontal and spectral resolutions) and more rapid revisit while reducing the size and complexity of the instrument. We briefly revisit the technology used in the Atmospheric Infrared Sounder (AIRS), recognizing that it was developed in the 1990’s and has matured key technologies in the areas of IR detectors, optical coatings, gratings, and cryocoolers. AIRS has been an unqualified success not only as a science and operational mission but also as a technology demonstration of the reliability and simplicity of grating spectrometer IR sounding instruments. Advancements in focal plane arrays (FPAs) have enabled a new class of grating spectrometer IR sounders that offer more spectral channels on a single FPA, mitigating some of the issues seen in AIRS that used linear arrays. These improvements have been manifested in the CubeSat Infrared Atmospheric Sounder (CIRAS) brassboard instrument, developed at the California Institute of Technology Jet Propulsion Laboratory with industry partner Ball Aerospace. Further enhancements beyond those used in CIRAS enable the development of a new class of instruments with a very long-wavelength infrared response and a very high spatial resolution (

The frequency-modulated continuous-wave (FMCW) radar is generally applied in ground target detecting devices mounted on small shells or projectiles because of its compact size. However, the FMCW radar often produces false alarms when detecting ground targets surrounded by heavy clutter. To overcome this problem, this paper proposes a ground target detection system based on both the miniaturized FMCW radar and the total power radiometer (TPR), consisting of the common millimeter-wave (MMW) front ends and an antenna. However, its intermediate frequency (IF) parts are separated using different frequency bands to miniaturize the entire system. The minimum detectable temperature (MDT) increases and the sensitivity is thus degraded because the TPR for the hybrid sensor inevitably includes an undesirable transmitter section owing to the widespread usage of the front ends with the radar. The proposed system employs optimization of the physical path delay and duplexing the IF band for the TPR and FMCW radar to improve the sensitivity of the TPR in the proposed hybrid sensors and reduce the system noise. The system includes a matching circuit and a voltage doubler to improve the sensitivity of the detector. Therefore, the MDT of TPR in the proposed hybrid system can be reduced to 47.5 K from 734.6 K in the initial design. The drop test demonstrates that the proposed hybrid sensor can reduce false alarms when compared to using either the FMCW radar or only the TPR.

This article presents a wide-spectral response single photon avalanche diode (SPAD) designed and fabricated in advanced 55-nm CMOS image sensor technology. SPADs with different active areas and doping profiles are simulated by Sentaurus-TCAD to optimize their electrical and optical performances. A global well-sharing technique is employed to deliver a pixel pitch of $16.4 ~\mu \text{m}$ and a fill factor of 50.96% for a device with a $6 ~\mu \text{m}$ radius. The proposed structure is based on a p+/deep n-well (DNW) multiplication junction, extending its spectral response as much as possible. Compared to the existing BSI SPADs, a triple protection method is innovatively used to suppress premature edge breakdown and to reduce the dark count rate (DCR) through a combination of a virtual retrograde DNW, p-well guard ring, and a poly gate ring located above the shallow trench isolation. Furthermore, deep trench isolation is employed to suppress crosstalk. Samples of different radii from 2 to $6 ~\mu \text{m}$ are manufactured. The SPADs exhibit a low DCR below 20 cps/ $\mu \text{m}$ 2 at room temperature and with a 2-V excess bias. The peak photon detection probability is 20.3% at 660 nm and is maintained at a high value, more than 10%, in the spectral range of 550–820 nm. [ABSTRACT FROM AUTHOR]

In the field of high energy particle imaging detection, there is an urgent requirement for detectors with radiation hardness and thermal resistance. Here, we design a 4H-SiC pixel detector based on a $4\times4$ p-i-n diode array. The thickness of sensitive region (epitaxial layer) is up to $90 ~\mu \text{m}$ , which could realize the detection of 6-MeV tritium. The active area of one p-i-n diode is 1.6 mm $\times1.6$ mm. With an excellent design of gradual doping space modulated (GDSM) junction termination extension (JTE), the reverse bias voltage is up to 5 kV, and the average leakage current is lower than 70 pA when the reverse bias voltage is 400 V. Based on a 16-channel readout electronic system, this detector shows good performance in the position resolution experiment for 5.4-MeV $\alpha $ particles. [ABSTRACT FROM AUTHOR]

The design and fabrication of InP Mie resonators as a broadband anti-reflection coating for InGaAs/InP FPA sensors have been reported in this work. Using the finite-difference time-domain (FDTD) simulator, we obtained a reflectivity lower than 5% over the whole spectrum of 900 – 1650 nm, with the optimized structure of 200 nm height, 360 nm side length and 600 nm period InP resonators. The characterization was contrasted between the InGaAs focal plane array (FPA) with and without InP Mie resonators with measurements of the blackbody response signal, the noise and the quantum efficiency. A 16.7% improvement of the peak responsivity in the structured area has further demonstrated the promising prospect of such design in the application of InGaAs sensors as well as other spectral domain detectors. [ABSTRACT FROM AUTHOR]

Fiber Bragg gratings (FBGs) are a potential alternative to piezoelectric ultrasound sensors for applications that demand high sensitivity and immunity to electromagnetic interference (EMI). However, limited data exist on the quantitative performance characterization of FBG sensors in the MHz frequency range relevant to biomedical ultrasound. In this work, we evaluated an FBG to detect MHz-frequency ultrasound and tested the feasibility of measuring passive cavitation signals nucleated using a commercial contrast agent (SonoVue). The sensitivity, repeatability, and linearity of the measurements were assessed for ultrasound measurements at 1, 5, and 10 MHz. The bandwidth of the FBG sensor was measured and compared to that of a calibrated needle hydrophone. The FBG showed a sensitivity of 0.99, 0.769, and 0.818 V/MPa for 1, 5, and 10 MHz ultrasound, respectively. The sensor also exhibited linear response ($0.975\leq {R}$ -Squared ≤ 0.996) and good repeatability with a coefficient of variation (CV) less than 5.5%. A 2-MHz focused transducer was used to insonify SonoVue microbubbles at a peak negative pressure of 175 kPa and passive cavitation emissions were measured, in which subharmonic and ultraharmonic spectral peaks were observed. These results demonstrate the potential of FBGs for MHz-range ultrasound applications, including passive cavitation detection (PCD). [ABSTRACT FROM AUTHOR]

One common computer vision task is to track an object as it moves from frame to frame within a video sequence. There are a myriad of applications for such capability and the underlying technologies to achieve this tracking are very well understood. More recently, deep convolutional neural networks have been employed to not only track, but also to classify objects as they are tracked from frame to frame. These models can be used in a tracking paradigm known as tracking by detection and can achieve very high tracking accuracy. The major drawback to these deep neural networks is the large amount of mathematical operations that must be performed for each inference which negatively impacts the number of tracked frames per second. For edge applications residing on size, weight, and power limited platforms, such as unmanned aerial vehicles, high frame rate and low latency real time tracking can be an elusive target. To overcome the limited power and computational resources of an edge compute device, various optimizations have been performed to trade off tracking speed, accuracy, power, and latency. Previous works on motion based interpolation with neural networks either do not take into account the latency accrued from camera image capture to tracking result or they compensate for this latency but are bottlenecked by the motion interpolation operation instead. The algorithm presented in this work gains the performance speedup used in previous motion based neural network inference papers and also performs a novel look back operation that is less cumbersome than other competing motion interpolation methods.

A compact monolithic trantenna (transistor-antenna) device is presented for a high-performance sub-THz wave detector using 28-nm CMOS foundry process. Based on a highly localized plasmonic wave in a silicon nano-ring field-effect transistor (FET), we obtained a total 535-fold photoresponse ($\Delta {u}$) enhancement in an on-chip measurement as compared with our previous works using the same asymmetry ratio ($\eta _{a}= 30$). The inner contact diameter (${d} _{\textit {in}}$) was scaled down from 8 to $0.13 ~\mu \text{m}$ for the parasitic resistance limit case. By changing the ground source from inside to outside the nano-ring FET, we could generate different $\Delta {u}$ polarities, which in turn reduced the junction leakage with improved $|\Delta {u}|$. From a fabricated nano-ring FET with the outer ring grounded source, we observed $5\times $ of additional $|\Delta {u}|$ enhancement followed by $107\times $ with ${d} _{\textit {in}}$ scaling. In addition, based on the highly localized plasmonic wave nano-ring FET without any external gain, a record-high free-space responsivity of 12.4 kV/W and a reduced noise equivalent power of 1 pW/Hz $^{0.5}$ were experimentally demonstrated under 0.12-THz radiation. [ABSTRACT FROM AUTHOR]

This paper proposes orthogonal time sequency multiplexing (OTSM), a novel single carrier modulation scheme that places information symbols in the delay-sequency domain followed by a cascade of time-division multiplexing (TDM) and Walsh-Hadamard sequence multiplexing. Thanks to the Walsh Hadamard transform (WHT), the modulation and demodulation do not require complex domain multiplications. For the proposed OTSM, we first derive the input-output relation in the delay-sequency domain and present a low complexity detection method taking advantage of zero-padding. We demonstrate via simulations that OTSM offers high performance gains over orthogonal frequency division multiplexing (OFDM) and similar performance to orthogonal time frequency space (OTFS), but at lower complexity owing to WHT. Then we propose a low complexity time domain channel estimation method. Finally, we show how to include an outer error control code and a turbo decoder to improve error performance of the coded system. [ABSTRACT FROM AUTHOR]

Detective properties of a GaAs-based position sensitive detector (PSD) employing a very thin, highly doped p±-GaAs layer as a resistive layer were investigated. In addition to photovoltaic voltages, photovoltaic currents from a three-terminal PSD with two lateral electrodes and one transverse common electrode were also studied. In particular, lateral photovoltaic currents flowing into the two lateral electrodes and/or their differential values, instead of transverse photovoltaic currents were used as output signals. To do so, a PSD itself without power supply was proposed to realize its suitability for applications. When a 2 mW 638 nm light spot was used as an input, a position sensitivity of 38.5 μA/mm, a correlation coefficient (or linearity) of > 0.999, and a nonlinearity (or position error) of 1.25% were obtained for our GaAs-based PSD with a long distance of 14 mm between two lateral electrodes. Besides, an equivalent circuit with a point solar cell was proposed to successfully explain these photovoltaic currents found in various configured 2-terminal and 3-terminal PSDs.

The negative selection algorithm (NSA) is one of the basic algorithms of the artificial immune system. In the traditional negative selection algorithm, candidate detectors are randomly generated without considering the uneven distributions of self-antigens and nonself-antigens, thereby resulting in many redundant detectors, and it is difficult for these detectors to fully cover the area of nonself-antigens. To overcome the problem of low detector generation efficiency, a negative selection algorithm that is based on antigen density clustering (ADC-NSA) is proposed in this paper. The algorithm divides the process of detector generation into three steps: the first step is to calculate the density of the antigens by using the method of antigen density clustering to select nonself-clusters. The second step is to prioritize the abnormal points (nonself-antigens that are not clustered) as the centers of candidate detectors and to generate the detectors via calculation. The third step is to generate the detectors via the traditional algorithm. Detector generation via these three steps can reduce the randomness of the detector generation in the traditional algorithm, thereby improving the efficiency of detector generation. The experimental results demonstrate that on the BCW and KDD-Cup datasets, the negative selection algorithm that is based on antigen density clustering can effectively increase the detection rate while reducing the false-positive rate compared with the traditional negative selection algorithm (RNSA) and two improved algorithms at the same expected coverage.

The FragmentatiOn mymargin Of Target (FOOT) experiment aims to provide precise nuclear cross section measurements for two different fields: hadrontherapy and radio-protection in space. The main reason is the important role the nuclear fragmentation process plays in both fields, where the health risks caused by radiation are very similar and mainly attributable to the fragmentation process. The FOOT experiment has been developed in such a way that the experimental setup is easily movable and fits the space limitations of the experimental and treatment rooms available in hadrontherapy treatment centers, where most of the data takings are carried out. The trigger and data acquisition system needs to follow the same criteria and it should work in different laboratories and different conditions. It has been designed to acquire high statistics samples to fulfill the accuracy requirements of the physics analysis. Data-taking is being monitored online to allow the shift crew to verify the correct functioning of the system. [ABSTRACT FROM AUTHOR]

A terahertz (THz) attenuation calibration system is developed using a photoacoustic (PA) detector for free-space beams. Based on the principle of the PA detector, the system measures the THz attenuation by substituting radio frequency (RF) attenuation with audio frequency (AF) attenuation. The AF attenuation at 1 kHz is directly calibrated using an inductive voltage divider (IVD) as the reference standard. The calibration is demonstrated for metalized film attenuators up to 20 dB at 0.11 THz. A Gunn oscillator with a corrugated horn antenna is used as the source, and its radiated beam is collimated using an off-axis parabolic mirror. Sources of uncertainties are also discussed in detail, and the expanded uncertainty is found to be 0.40–0.46 dB ($k = 2$). [ABSTRACT FROM AUTHOR]

In this work, TCAD-based investigation of junctionLess (JL) architecture having double gate (DG) has been performed for visualizing the sensitivity of the device against light intensity. Comparison has been drawn between conventional DG MOSFET and DG-JL transistor (DG-JLT) under dark and light conditions. Effect of light intensity and wavelength has been modulated to optimize the device sensitivity. Higher shift in the drain current (in subthreshold region) has been observed at 0.35 μm of wavelength, i.e., more sensitive to ultraviolet (UV) light. The improved sensitivity of DG-JLT as compared to DG-MOSFET is due to the better subthreshold characteristics of the device (i.e., lower leakage current and subthreshold slope). From the results, it can be concluded that the DG-JLT with channel doping of 1019 cm−3, 10 nm of channel thickness, and having 1 nm of oxide thickness is the best possible choice for UV photodetector due to high sensitivity and responsivity. It has also been observed that more optimizing parameters are available with DG-JLT as the DG-MOSFET is immune toward the device parameter variation. [ABSTRACT FROM AUTHOR]

Negative selection algorithm (NSA) is an important detector generation algorithm of artificial immune system (AIS). Traditional NSAs randomly generate detectors in the whole antigen space without considering the distribution of self/non-self antigens, therefore it is difficult for detectors to cover the whole antigen space evenly and a seriously time-consuming self-tolerance process is required. Aiming at the problem, we proposed a novel NSA based on antigen space triangulation coverage (ASTC) called ASTC-RNSA. In order to avoid the randomness in traditional NSAs, the proposed algorithm employed Delaunay Triangulation method from computational geometry to divide the self space into simplicial cells, which are utilized to determine the detector positions. Then, the overlaps between simplicial cells and self-antigens are removed to form a set of triangulation coverage areas. Finally, immune detectors which only covered non-self antigens space are generated in each triangulation coverage area. After Delaunay triangulation of antigen space, ASTC-RNSA can directly determine sui detector positions and avoid the time-consuming self-tolerance process of traditional NSAs. The analysis result shows that the time complexity of ASTC-RNSA is reduced from traditional exponential level to logarithmic level. The experimental results on several UCI datasets and artificial datasets show that the proposed algorithm can achieve more than 10 times the detector generation efficiency while maintaining similar detection performance with the most widely used representative typical algorithm, V-Detector.

In the field of arc fault detection, it is universally acknowledged that it is very hard to judge whether there is an arc fault through signals of the main line when a masking load (such as air compressors, lamps with dimmers, and so on) is in parallel with a resistive load, which always tends to be a fire hazard. Meanwhile, it is annoying that the normal currents of some appliances are very similar to the arcing ones. In this paper, we have found the principles of a novel detection method called high-frequency coupling, putting the neutral line (N) and the live line (L) through the current transformer (CT), which results in asymmetrical distribution of magnetic flux in the core and the only high-frequency components left in the secondary output of the CT. So it is possible for series arc fault detectors to be free from the masking loads and distinguish between the arcing and the nonarcing clearly. Thanks to this convenient method, an arc fault detector based on the microcontroller unit (MCU) has been proposed to detect arc faults effectively by means of simple multi-indicators. The experimental results show the accuracy of arc fault recognition, in all the masking tests, can reach a high level and the detector can detect an arc fault within a short time.

When the target is partially occluded or undergoes drastic appearance change, drift is prone to occur in traditional correlation filter-based trackers and ultimately leads to tracking failure. This paper proposes a robust tracking algorithm, which can be applied to practical engineering. The proposed algorithm divides all training samples into different training sets based on their similarities. An independent filter is trained for every training set. In each frame of the tracking process, the similarity between the candidate region and any training set's training samples is calculated to select the most matched filter for target location. As a newly introduced training sample, a feature map within the current frame's estimated target bounding box is assigned to the most similar training set to update the most matched filter. The updating of each filter is relatively independent. Each filter corresponds to one kind of target's typical appearance, and thus, the proposed tracking algorithm can memorize a variety of typical target appearances that appeared in the past and adapt to target's discontinuous appearance change. The detector improves tracking accuracy and assists occlusion judgment. After occlusion, the target may reappear with a different posture. As long as similar postures have been captured in the previous tracking process, the target can be retrieved accurately while not being confused with other objects of the target's category. We evaluated our method on massive videos shot in actual engineering sites, and the result demonstrates that the proposed tracking algorithm can handle occlusion and target's posture changes very well and significantly outperforms other tracking algorithms.

Dark current and associated random telegraph signals are studied in short-wave infrared image sensors. The effects of space radiation on these parameters are analyzed and modeled to understand the degradation in this indium–gallium–arsenide (InGaA)-based technology. Multiple proton tests were performed to cover the space mission range of radiation dose. Comparison with existing data and damage factors is provided and highlights the behavior of such technology against radiation doses. [ABSTRACT FROM AUTHOR]

The quadruped robot imitates the motions of four-legged animals with a superior flexibility and adaptability to complex terrains, compared with the wheeled and tracked robots. Its leader-following ability is unique to help a human to accomplish complex tasks in a more convenient way. However, long-term following is severely obstructed due to the high-frequency vibration of the quadruped robot and the unevenness of terrains. To solve this problem, a visual approach under a novel T-D-R framework is proposed. The proposed T-D-R framework is composed of a visual tracker based on correlation filter, a person detector with deep learning, and a person re-identification (re-ID) module. The result of the tracker is verified by the detector to improve tracking performance. Especially, the re-ID module is introduced to handle distractions and occlusion caused by other persons, where the convolutional correlation filter (CCF) is employed to discriminate the leader among multiple persons through recording the appearance information in the long run. By comparing the results of the tracker and the detector as well as their similarity scores with the leader identified by the re-ID module, a stable and real-time tracking of the leader can be guaranteed. Experiments reveal that our approach is effective in handling distractions, appearance changes, and illumination variations. A long-distance experiment on a quadruped robot indicates the validity of the proposed approach. [ABSTRACT FROM AUTHOR]

Modern smart grid relies on various sensor measurements for its operational control. In a successful false data injection attack, the attacker manipulates the measurements from the grid sensors such that undetected errors are introduced into the estimates of the system parameters leading to catastrophic situations. This article proposes a novel perturbation based false data injection attack detection mechanism that utilizes inverter based distributed energy resources (DERs) to create low magnitude perturbation signal in the distribution system voltage that is inconsequential to the normal grid operation. Two voltage sensitivity analysis based algorithms are designed to identify the optimal set of DERs that can create the voltage perturbation signal of desired magnitude. An analytical method of voltage sensitivity analysis is used to compute the magnitude of voltage perturbation signal at each node in a computationally efficient manner. Then, a detection mechanism is developed that checks for the presence of the perturbation sequence in each sensor measurement. A sensor measurement is deemed authentic if the voltage perturbation signal is present in the data. In case of sensor malfunction or cyber-attack, the perturbation signal will not be present in the measurement data. Performance of the proposed attack detection mechanism is validated via simulation of the IEEE 69 bus test system. [ABSTRACT FROM AUTHOR]

This paper presents a linear complexity iterative rake detector for the recently proposed orthogonal time frequency space (OTFS) modulation scheme. The basic idea is to extract and coherently combine the received multipath components of the transmitted symbols in the delay-Doppler grid using maximal ratio combining (MRC) to improve the SNR of the combined signal. We reformulate the OTFS input-output relation in simple vector form by placing guard null symbols or zero padding (ZP) in the delay-Doppler grid and exploiting the resulting circulant property of the blocks of the channel matrix. Using this vector input-output relation we propose a low complexity iterative decision feedback equalizer (DFE) based on MRC. The performance and complexity of the proposed detector favorably compares with the state of the art message passing detector. An alternative time domain MRC based detector is also proposed for even faster detection. We further propose a Gauss-Seidel based over-relaxation parameter in the rake detector to improve the performance and the convergence speed of the iterative detection. We also show how the MRC detector can be combined with outer error-correcting codes to operate as a turbo DFE scheme to further improve the error performance. All results are compared with a baseline orthogonal frequency division multiplexing (OFDM) scheme employing a single tap minimum mean square error (MMSE) equalizer. [ABSTRACT FROM AUTHOR]

In this paper, a twin-FET (field effect transistor) THz detector monolithically integrated with a dual-feed antenna is presented. The antenna-detector configuration can be extended for ’N’ FET elements to relax the input impedance requirement for the detector readout circuitry while maintaining good responsivity. A dual-feed octagonal slot antenna is used to couple THz radiation and provide differential excitation to the twin-FET detector. The multi-feed antenna-FET detector interface can be designed for an arbitrary phase excitation of one or more FET elements. Fabricated in Global Foundries 22nm FD-SOI process, the proposed detector covers a measured frequency range from 220 GHz to 300 GHz. Such bandwidth is sufficiently wide to capture reliable spectral information for distinguishing a number of gases in a mixture. The absorption spectra of pure methanol, chloromethane and acetonitrile are measured using a rotational spectroscopy setup incorporating the twin-FET detector. Detection of a small concentration of acetonitrile, at 4 Torr pressure, is demonstrated in a binary mixture with predominantly chloromethane. Detection of ethanol and methanol in their binary mixture is also demonstrated at 4 Torr pressure. This is a significant step towards the development of all-electronic THz spectroscopy for the detection of volatile organic compounds (VOCs) in the presence of contaminants with a strong THz absorption signature at >1 Torr pressure. [ABSTRACT FROM AUTHOR]

We report on the response of a monolithic high $\mathrm{T_{c}}$ transition-edge bolometer to about 3 mmWave for the first time. The detector structure consisting of 400-nm $\mathrm{YBa_{2}Cu_{3}O_{7-x}}$ (YBCO) film on buffered yttria stabilized zirconia substrate without any coupled antenna, shows bolometric type responsivity to the 3-mmWave radiation at its transition temperature. The YBCO thin film and $\mathrm{Ce_{0.9}La_{0.1}O_{2}}$ buffer layer are both fabricated by the metal-organic deposition method. The meander line pattern of the bolometer is designed for obtaining maximum absorption and responsivity possible when the polarized radiation of the source is aligned with the pattern. Meander lines are 50 micrometers wide and 1.5-mm long. We have measured amplitude and phase of the response versus modulation frequency of the detector to the linearly polarized 95-GHz source, and the detector was biased at five distinct temperatures at the transition corresponding to five different electrical conductivities of the YBCO film. When the meander lines of the device are parallel to the incident beam polarization, the YBCO pattern is speculated to act as a dissipative antenna resulting in higher absorption leading to high magnitude of the response as observed. The results from the measured phase of the response versus modulation frequency are also in agreement with the discussed absorbed mechanism. The absorption of the YBCO pattern is also measured to depend on the electrical conductivity of the YBCO film and our results show that there is an optimum electrical conductivity for having maximum absorption for this detector. Simulation results for this structure confirm the experiments showing that at electrical conductivity value of $\mathrm{1.33\times 10^{5}}$ S/m we have the maximum absorption for our device. These observations promise design of versatile THz and millimeter-wave detectors with potential for applications in medical and security imaging. [ABSTRACT FROM AUTHOR]

A comparison of Zinc Oxide (ZnO) phototransistors prepared by spray and sputter coating process is presented. The work shows that spray coated layers provide significant advantages in sensor response over ZnO phototransistors made by physical vapour deposition and we show that spray deposited ZnO phototransistors can exhibit state-of-the-art performances for UV photodetectors. Topographic images of the samples surface shows that there is increase in surface roughness in spray coated samples indicating increasing grain sizes, which is considered the source of the greater sensor responsivity. X-ray photoelectron spectroscopy (XPS) is also used to understand the root cause of the greater UV responsivity. It was observed that sprayed ZnO TFTs are more sensitive to UV radiation due to higher adsorption of oxygen level. Responsivity and external quantum efficiency (EQE) of the sprayed and sputtered ZnO TFTs are also evaluated. [ABSTRACT FROM AUTHOR]

This article presents a high data rate, high-efficiency 60-GHz on–off keying (OOK) CMOS transmitter and receiver. The transmitter consists of a voltage-controlled oscillator (VCO) and a modulator. The receiver consists of a low-noise amplifier, detector, and limiting amplifier (LA) and has a compact design. An analysis of the on–off isolation of the modulator and bandwidth of the LA reveals that the proposed transformer (TF) between the modulator and the VCO can improve the on–off isolation, and the feedforward capacitor can enhance the bandwidth. Implemented in the 65-nm CMOS technology, the transmitter and the receiver consume dc powers of 12.1 and 21 mW, respectively, at 12.5 Gb/s. Moreover, they occupy core chip areas of 0.09 and 0.06 mm2, respectively. The transceiver system is constructed with on-board Yagi–Uda antennas, and it achieves 12.5 Gb/s wireless OOK data transmission for a pseudorandom binary sequence of length 27 −1 with a bit error rate of less than 10−12. The proposed transceiver system achieves an energy efficiency of 2.65 pJ/bit. [ABSTRACT FROM AUTHOR]

We developed a new front-end application-specific integrated circuit (ASIC) to upgrade the Maia X-ray microprobe. The ASIC instruments 32 configurable channels that perform either positive or negative charge amplification, pulse shaping, peak amplitude, and time extraction along with buffered analog storage. At a gain of 3.6 V/fC, 1-μ s peaking time, and a temperature of 248 K, an electronic resolution of 13 and 10 e− rms was measured with and without a silicon drift detector (SDD) sensor, respectively. A spectral resolution of 170-eV full-width at half-maximum (FWHM) at 5.9 keV was obtained with an 55Fe source. The channel linearity was better than ± 1 % with rate capabilities up to 40 kcps. The ASIC was fabricated in a commercial 250-nm process with a footprint of 6.3 mm × 3.9 mm and dissipates 167 mW of static power. [ABSTRACT FROM AUTHOR]

Green low power networking with the least requirement of dedicated radio resources is need of the hour which has led to the upsurge of backscatter communication (BSC) technology. However, this inherent potential of BSC is challenged by hardware constraints of the underlying tags. We address this timely concern by investigating the practical efficacy of multiple-input-multiple-output (MIMO) technology in overcoming the fundamental limitations of BSC. Specifically, we first introduce a novel least-squares based channel estimation (CE) protocol for multi-tag BSC settings that takes care of both the unintended ambient reflections and the inability of tags in performing estimation by themselves. Then using it, a nontrivial low-complexity algorithm is proposed to obtain the optimal transceiver designs for the multiantenna reader to maximize the minimum value of the lower-bounded backscattered throughput among the single-antenna semi-passive tags. Additional analytical insights on both individually and jointly-optimal precoding vector and detector matrix at the reader are provided by exploring the asymptotically-optimal transceiver designs. Lastly detailed numerical investigation is carried out to validate the theoretical results and quantify the practically realizable throughput fairness. Specifically, more than seven-fold increase in the common-backscattered-throughput among tags as achieved by the proposed designs over the relevant benchmarks corroborates their practical significance. [ABSTRACT FROM AUTHOR]

The design of the Moderate-Resolution Imaging Spectroradiometer (MODIS) instrument was driven by the scientific community’s desire to have near-daily global coverage at moderate resolution (~1km) with comprehensive spectral coverage from visible to long-wave infrared wavelengths. Since their launches in 1999 and 2002, respectively, the Terra and Aqua MODIS instruments have made continuous global observations and generated numerous data products to help users worldwide with their studies of the Earth’s system and its short- and long-term changes. The 20 reflective solar bands (RSBs) with wavelengths from 0.41 to $2.2~\mu \text{m}$ collect data at three nadir spatial resolutions: 250 m, 500 m, and 1 km. The solar diffuser (SD) coupled with the SD stability monitor (SDSM) provides a reflectance-based calibration on-orbit. In addition, lunar observations and response trends from pseudoinvariant desert sites are used to characterize the response versus scan-angle changes on-orbit. This paper provides a brief overview of MODIS RSB calibration algorithms, as implemented in the latest Level 1B version 6.1, operational activities, on-orbit performance, remaining challenges, and potential improvements. Results from the SD and SDSM measurements show a wavelength and mirror-side-dependent degradation in RSB responses, with the largest degradation at the shortest wavelengths, particularly for Terra MODIS. Aqua MODIS has experienced far less degradation of its optics and on-board calibrators compared with Terra MODIS, resulting in an overall better performance. With the exception of Aqua band 6, there have been no new noisy or inoperable detectors in the RSB of either instrument during postlaunch operations. As the instruments age and continue to endure the space environment, the detectors and the optical systems degrade. The challenges associated with incorporating these on-orbit changes to ensure a production of high-quality calibrated L1B data products are also discussed in this paper. [ABSTRACT FROM AUTHOR]

DUNE will be the world’s largest neutrino experiment and is due to take data in 2025. This paper describes the data acquisition (DAQ) system for one of its prototypes, ProtoDUNE-SP, which started taking data in Q4 of 2018. ProtoDUNE-SP also breaks records as the largest beam test experiment yet constructed and is a fundamental element of CERN’s Neutrino Platform. This makes ProtoDUNE-SP an experiment in its own right and the design and construction have been chosen to meet this scale. Due to the aggressive construction and commissioning timescale, off-the-shelf electronics have been chosen to meet the demands of the experiment where possible. The ProtoDUNE-SP cryostat comprises two primary subdetectors: a single-phase liquid-argon time projection chamber (LAr TPC) and a companion photon detector system. The TPC has two candidate readout solutions under test in ProtoDUNE-SP: RCE (ATCA-based) and Front-End Link EXchange (FELIX) (PCIe-based). Fermilab’s artdaq is used as the data handling software framework for the experiment. Custom timing and trigger electronics and software are also described. Triggering and lossless compression will take the 430 Gb/s of data from the front end and reduce it to 20-Gb/s bandwidth to permanent data storage in CERN’s EOS infrastructure. [ABSTRACT FROM AUTHOR]

Single crystals of Gd3Ga3Al2O12:Ce were grown successfully and a slice having thickness lesser than 1 mm was processed from the grown crystals to setup a portable thermal neutron detector. The presence of Gd isotopes having very high thermal neutron capture cross section ensures almost 100% stopping efficiency in such a low thickness. On the other hand, a lower thickness provided a better discrimination from gamma background. In addition to the continuum gamma, Gd isotopes also produce low-energy conversion electrons and X-rays which could be successfully observed in the form of well discriminated photopeaks at 34 and 74 keV. These photopeaks could also be measured in nuclear reactor beam lines with high gamma background. [ABSTRACT FROM AUTHOR]

Combatting nuclear terrorism is a 21st century grand challenge (US-NAE report-2008). This paper discusses how tensioned metastable fluid detector (TMFD) radiation sensors in large-array format attain and exceed the global challenge efficiency metric announced by the U.S. Department of Defense for detection of neutron emissions from special nuclear materials such as Plutonium. The challenge calls for detector array area $(A-cm^{2})$ times nuclear fission spectrum neutron detection fractional efficiency (${\epsilon }$) to exceed 1000; furthermore, using detectors in array form with linear dimension to not exceed 1 m based on use of He-3 based sensors—considered the industry “gold” standard. Based on experimentally validated efficiency of TMFD sensors, this paper presents evidence that an array of TMFDs (using either isopentane or trimethyl borate as sensing fluids) when optimally placed in array form can enable $\text{A}\times {\epsilon }$ ~ 2000—therefore, exceeding the challenge goal by over 100%. Additional advancements are reported on TMFD sensor characterizations for instrinsic efficiency of neutron detection (~80%) and spectroscopic alpha radiation emitter Pu/U isotopic detection (~99%) at $\times 100$ lower levels versus state-of-the-art spectrometers; comparisons versus conventional sensors are also presented—evidence is provided for $\times 75$ higher detection efficiency compared with the moderated BF3 industry standard and toward $\times 25$ to $\times 800$ versus NE-213 fast neutron detector standard. [ABSTRACT FROM AUTHOR]

Recent theories suggest that the photo thermoelectric effect dominates the photo response in graphene. Hot-carrier generation arising from carrier multiplication in graphene under the incident light is introduced as the main cause of this effect. Here, we investigate the possibility of GHz-THz direct detection in a graphene-based device through Hot-carrier effect. The proposed structure is a Schottky junction between graphene and Si. We have measured the optical properties of the junction under 86 GHz and 0.102 THz radiations at room temperature. We have repeated the experiments at cryogenic temperatures down to 150 K. The minimum responsivity of the junction is measured as $2\boldsymbol {\times } 10^{\mathbf{4}}$ V/W under 0.102 THz radiations at room temperature. This value increases five-fold at the cryogenic temperatures. We discuss the physics behind room temperature operation of the device based on the photo thermoelectric effect and the hot-carrier generation in graphene under the illuminations. Room temperature and direct detection of GHz and THz radiation in the graphene-Si junction can be practical evidence of hot-carrier generation in graphene under the incident illuminations. [ABSTRACT FROM AUTHOR]

Sparse code multiple access (SCMA), a novel non-orthogonal multiple access scheme for fifth generation wireless, has drawn much attention. Since optimal SCMA detection incurs high computational complexity, we develop a modified single tree search (MSTS) to obtain soft outputs for coded SCMA. The MSTS algorithm incorporates the sorting of the channel matrix and computing a non-zero low bound before searching in order to reduce complexity during the search stage. The simulation results show that MSTS not only has lower computational complexity than detectors based on the message passing algorithm (MPA) and repeat tree search but also keeps its performance level close to that of MPA. [ABSTRACT FROM AUTHOR]

Polarized Drell-Yan measurements require a strong homogeneousmagnetic field. A 2.5 T longitudinal field is generated with a superconducting solenoid carrying a nominal current of 650 A, while high homogeneity is obtained by using additional shim--and compensation coils. Since the target needs to be transversely polarized, a second main coil is required. A superconducting dipole coil encloses the solenoid and together they are integrated in a common cryostat. Field rotation, from longitudinal to transverse and vice versa, is possible by simultaneously powering both coils. During the complete procedure, the absolute field strength is never allowed to drop below0.48 T to guarantee a high polarization percentage. In the meantime, the forces between the coils need to be controlled, and therefore the coils cannot both be carrying the nominal operational current, since this will destroy the system. The magnetic field rotation procedure is therefore uniquely developed for this system. In this paper, the magnet system is described and a summary of the operational experience gained during data taking is provided. [ABSTRACT FROM AUTHOR]

We consider millimeter wave multiuser uplink system with low resolution phase shifters, where users transmit simultaneously to base station. Transmit and receive beamforming through large antenna arrays is used to compensate severe path loss of millimeter waves. We first propose a joint precoder and detector design based on the low-complexity local search algorithm that iteratively finds the preferred transmit and receive beamforming vectors, which maximizes the sum-rate of the multiuser uplink system. Although the joint design achieves similar sum-rate to a fully digital system, the computation complexity to determine good beamforming vectors is high. To reduce complexity, we then propose nonjoint designs of precoder and detector. For the precoder design, the transmit beamforming vectors are chosen to maximize either the signal to noise ratio or the signal to interference plus noise ratio of each user. For the detector design, the receiver beamforming vectors are selected using either an approximate ML detector or a successive cancellation detector. Through simulations, we show that our designs with low resolution phase shifters outperform the traditional methods using steering vectors as beamforming vectors with high resolution phase shifters. [ABSTRACT FROM PUBLISHER]

In this paper, a receiver architecture is presented which is capable of handling angle-of-arrival (AOA) detection as well as data communication. The architecture of the proposed multifunction receiver is based on the multiport interferometer technique, and it integrates two previously reported six-port-based system functions that were realized as two distinct six-port receivers (SPRs). This unification of two SPRs is mainly achieved through a new configuration of RF/local oscillator (LO) signals at input ports, a new phase processing of the input signals within a structured eight-port passive network and a complementary postprocessing of the signals at the output of detectors. Using two RF input ports and two LO input ports that are switched in two consecutive time slots, the proposed multiport-based receiver (MPR) can estimate the AOA with a simple signal-processing algorithm. The plurality of the RF input ports can cause self-interference for the received communication signals. Therefore, a phasing network within the proposed eight-port wave correlator is devised such that the incoming quadrature modulated RF carriers are demodulated in an orthogonal manner at four output ports. It is found that receiving communication signal from a nonzero AOA makes imbalance between demodulated components. To this end, the proposed MPR can first find the angular position of the other unit and then recover the demodulation components through data fusion and postprocessing. The mathematical model for the developed MPR is derived along with the development of an appropriate calibration technique, and its principal functionality is theoretically analyzed. In addition, a transceiver architecture based on this MPR is implemented, and prototyped for operation around 77 GHz. The techniques for hybrid millimeter-wave system integration are explained in this paper. The proposed concept is proven and concluded with satisfactory measurements for both functions. This unified multifunction MPR can find applications in the future vehicle-to-vehicle radios and joint radar-communication systems. [ABSTRACT FROM PUBLISHER]

The system and transistor-level design of low-power millimeter wave (mm-wave) active tags in silicon is discussed in detail. Two active mm-wave tags with identical system architecture, padframe, and chip size were designed and fabricated in 55-nm SiGe BiCMOS and 45-nm SOI CMOS technologies, respectively. They feature a three-stage low-noise amplifier (LNA), a wake-up detector, a BPSK modulator, and two variable gain output stages, each driving a separate transmit antenna in antiphase. The wake-up detector can be used to switch OFF all the blocks except for the LNA and detector, thus further reducing power consumption. The measured performance of the SiGe and SOI chips is remarkably similar: 19- and 20-dB gain, 9- and 8-dB noise figure, and 25-/10.8-mW (active/idle) and 18-mW power consumption, respectively. The SiGe tag was flip-chip-mounted on a mini-PCB with one receive and two transmit antennas for system level functionality tests carried out over a distance of 5 m. The SiGe-tag wake-up sensitivity was verified to be −62 dBm, in excellent agreement with simulation results. [ABSTRACT FROM PUBLISHER]