Digital Array Research Articles

Computational array — digital array with computational empowerment

Computational array is a new generation digital array that deeply integrates computing and sensing. By introducing unit computing, a three-level computing architecture of “element -module -system" is constructed at the transmitting and receiving terminals, which can not only develop the transmitting freedom of a digital array but also maximize the use of perceptual data to meet the needs of transmission and distributed computing in large tasks and solve the transmission and processing pressure of massive data in digital array. This paper reviews the computational array and mainly introduces the concept and connotation, capability advantages and applications, design and implementation, and future developments.

CNN-32DC: An improved radar-based drone recognition system based on Convolutional Neural Network

This paper proposes a system that will guard infrastructures against incoming threats from drones by detecting it with the use of a radar device-based detection scheme. The database acquired, named Real Doppler RAD-DAR (Radar with Digital Array Receiver) is constructed by a Microwave and Radar Group. The radar used uses a Frequency Modulated Continuous Wave (FMCW) on an 8.75 GHz based frequency band with a BW m a x of 500 MHz. The proposed Convolutional Neural Network (CNN), CNN-32DC is varied with different number of filters, combination layers, and number of feature extraction blocks, the preference that will give the most accurate result was selected and compared with different machine learning and classification learning algorithms gained an accuracy that exceeds other networks with less processing time.

The impact of digital technologies on the modernization of management in Russian oil and gas companies in the context of global challenges

Aim. The presented study aims to outline directions for the modernization of management in Russian oil and gas companies forming under the influence of high-tech knowledge-intensive production cycles, human capital, and artificial intelligence with allowance for the global challenges of digital technologies.Tasks. The authors investigate theoretical and practical approaches to structural changes in the management of Russian oil and gas companies that lead to the continuous modernization of the life cycle of technological chains and innovative scenarios for the development of economic entities in the long term; consider management decisions from the perspective of targets and costs, since management systems are significantly corrected under the influence of global challenges in a unified digital model of regional socio-economic development.Methods. This study uses dialectical scientific methods of cognition, complex analysis of tools used in the formation of intellectual capital on the basis of integration processes of Internet mobility, cloud computing, analytical business processes of managerial influence and social media networks, synergetic effects in the modernization of management in oil and gas companies. The study also examines scenario approaches to the development of the economic segments of the real sector through the example of ten systemically important Russian companies.Results. Digital transformation of management in oil and gas companies based on blockchain tools, artificial intelligence, online banking, trade marketplaces, and targeted advertising determines the priorities of industrial development of national economic models in the context of global challenges. The conducted scientific analysis shows a significant modernization of management in the domains of information and analytical data processing, expert evaluation of the digital array of indicators, and marketing approaches of companies driving innovative development, which actively use crowdsourcing, public interfaces, cloud technologies, virtual space, artificial intelligence, and robotics in justifying scenarios for long-term development and enhancing the competitiveness of the oil and gas sector of the Russian economy.Conclusions. Priority directions for the modernization of management in oil and gas companies are based on the use of modern digital shells, IT platforms, services involving the introduction of structural resource-saving materials, and additive technologies. The transformational model of company management involves the use of modern management tools that make it possible to optimize asset management, forecasting systems, and monitoring of strategic business units aimed at optimizing budgeting in order to increase the efficiency of project activities. A comprehensive assessment of the management of economic entities in the context of global challenges is based on criteria for assessing the functioning of internal or external accelerators, business incubators, venture incentives, the availability of innovative potential for the implementation of promising projects in the Russian oil and gas complex in the context of global challenges using public-private partnership tools on the platforms of modern software products.

От (анти)вакцинаторства до (анти)выборов: особенности электоральных ориентаций противников вакцинации в России

 The article presents the results of applied research aimed at detecting the relationship between anti-vaccination strategies and electoral orientations of Russians. The research method is based on the comparison of digital data arrays devoted, on the one hand, to the study of digital activity of anti-vaccination movement, on the other hand, to a comprehensive analysis of information flows of Russian political parties through modern methods and tools of social media analytics. According to the results of the study, the authors conclude that there is no significant relationship between the political and party preferences of citizens and their anti-vaccination activity. The activities of Russian anti-vaxxers are rather aimed at ignoring elections as a derivative of the state system, to which there is a clear distrust. Despite the conscious use of anti-vaccination discourse by some party forces, the results of such work are limited in advance and may backfire.

Low-Velocity Impact, Free-Fall Drop Test of Prototype, and Failure Analysis of Hybrid Palm / Kenaf Reinforced MWCNT Phenolic Composites

ABSTRACT The research’s aim is to investigate the energy absorption, free-fall drop analysis, and failure analysis of Palm (P)/kenaf (K) fiber-reinforced MWCNT-phenolic composites. 3P:7K reinforced MWCNT–phenolic composites were made using manual mixing and hot pressing at 150°C with a pressure of 10 tonnes. Energy absorption was investigated using a drop weight impact tester. Free-fall drop test was performed to analyze the performance of the aircraft tray table prototype. Non-destructive testing was carried out to investigate the damage mechanism. The results demonstrate that as the impact energy increased from 1.50 J to 3.0 J, the crack length increased. There is a difference of 3% to 15% in the crack sizing between dye penetration and Digital Detector Array (DDA), indicating that DDA is more accurate. In the free-fall drop test, small cracks were detected in the dye penetration method on the prototype. The DDA approach, however, did not reveal any defects. The agglomerations were observed through DDA and Computed tomography. In this study, the hybrid CR/kenaf reinforced MWCNT modified phenolic composites exhibit superior performance that can act as an efficient and eco-friendly material for aircraft tray table application by preserving natural resources.

Implementation of stochastic signal processing algorithms in radar CAD

Objectives. In 2020, development work on the creation of a Russian computer-assisted design system for radars (radar CAD) was completed. Radar CAD provides extensive opportunities for creating simulation models for developing the hardware-software complex of radar algorithms, which take into account the specific conditions of aerospace environment observation. The purpose of the present work is to review and demonstrate the capabilities of radar CAD in terms of implementing and testing algorithms for processing stochastic signals.Methods. The work is based on the mathematical apparatus of linear algebra. Analysis of algorithms characteristics was carried out using the simulation method.Results. A simulation model of a sector surveillance radar with a digital antenna array was created in the radar CAD visual functional editor. The passive channel included the following algorithms: algorithm for detecting stochastic signals; algorithm for estimating the number of stochastic signals; direction finding algorithm for stochastic signal sources; adaptive spatial filtering algorithm. In the process of simulation, the algorithms for detecting and estimating the number of stochastic signals produced a correct detection sign and an estimate of the number of signals. The direction-finding algorithm estimated the angular position of the sources with an accuracy of fractions of degrees. The adaptive spatial filtering algorithm suppressed interfering signals to a level below the antenna's intrinsic noise power.Conclusions. The processing of various types of signals can be simulated in detail on the basis of the Russian radar CAD system for the development of functional radar models. According to the results of the simulation, coordinates of observing objects were obtained and an assessment of the effectiveness of the algorithms was given. The obtained results are fully consistent with the theoretical prediction. The capabilities of radar CAD systems demonstrated in this work can be used by specialists in the field of radar and signal processing.

Design, Micro-Fabrication, and Characterization of a 3-DoF Micro-Conveyor Based on Digital Actuators

In this paper, a novel optimal 3-DoF micro-conveyor based on electromagnetic digital actuators array is proposed. The micro-conveyor consists of four electromagnetic digital actuators. Two specific control strategies have been built to realize the 3-DoF planner conveyance task. A static analytical model and a dynamic semi-analytical model based on the principle have been built for the optimal design, analysis, and necessary calculation of a prototype. The prototype was manufactured by micro-fabrication technology and several experiments were carried out. The experimental results are in good agreement with the modeling results. Benefited from the optimal design and high fabrication precision, the proposed micro-conveyor is proved to be better in magnetic homogeneity of elementary actuators, output stability, long range conveyance linearity, and have one more DoF (planar rotation) compared to the previous work.

The Effect of Space Objects on Ionospheric Observations: Perspective of SYISR

Space objects around the Earth are a potential pollution source for ground-based radio observations. The Sanya incoherent scatter radar (SYISR) is a newly built active digital phased array, all solid-state transmitting and digital receiving incoherent scatter radar in Sanya (18.3°N, 109.6°E), with the main purpose of ionospheric monitoring and investigations. In this study, we presented the effect of the greatly increased number of space objects on ionospheric observations through SYISR. Firstly, we showed the space object pollution on the range-time-intensity (RTI), autocorrelation function (ACF)/power spectra, and ionosphere parameter of SYISR measurements. An altitude of around 600 km is the region where space objects occur most frequently. Then, we eliminated the space object pollution using the traditional smallest of constant-false-alarm-rate (SO-CFAR) algorithm. However, pollution from smaller space objects remains, whose reflected echo is comparable to or lower than the background ionosphere, which results in unrealistic retrieved ionospheric electron density. Furthermore, we quantitatively assessed the space object effect based on the current space object orbit database and simulation. The pollution should linearly increase with the increase in the number of space objects in the future. Among the space objects, whose radar cross section (RCS) and orbit information are now published, there still exist ~9000 (~37% of the total number) space objects, whose effect is difficult to eliminate. This study is beneficial to the data process of SYISR and has implications for similar types of ionospheric observations by radar.

Antenna Array Enabled Space/Air/Ground Communications and Networking for 6G

Antenna arrays have a long history of more than 100 years and have evolved closely with the development of electronic and information technologies, playing an indispensable role in wireless communications and radar. With the rapid development of electronic and information technologies, the demand for all-time, all-domain, and full-space network services has exploded, and new communication requirements have been put forward on various space/air/ground platforms. To meet the ever increasing requirements of the future sixth generation (6G) wireless communications, such as high capacity, wide coverage, low latency, and strong robustness, it is promising to employ different types of antenna arrays (e.g., phased arrays, digital arrays, and reconfigurable intelligent surfaces, etc.) with various beamforming technologies (e.g., analog beamforming, digital beamforming, hybrid beamforming, and passive beamforming, etc.) in space/air/ground communication networks, bringing in advantages such as considerable antenna gains, multiplexing gains, and diversity gains. However, enabling antenna array for space/air/ground communication networks poses specific, distinctive and tricky challenges, which has aroused extensive research attention. This paper aims to overview the field of antenna array enabled space/air/ground communications and networking. The technical potentials and challenges of antenna array enabled space/air/ground communications and networking are presented first. Subsequently, the antenna array structures and designs are discussed. We then discuss various emerging technologies facilitated by antenna arrays to meet the new communication requirements of space/air/ground communication systems. Enabled by these emerging technologies, the distinct characteristics, challenges, and solutions for space communications, airborne communications, and ground communications are reviewed. Finally, we present promising directions for future research in antenna array enabled space/air/ground communications and networking.

Simulation and Observational Evaluation of Space Debris Detection by Sanya Incoherent Scatter Radar

AbstractThe Sanya incoherent scatter radar (SYISR) is a newly built active digital phased array, all solid‐state transmitting and digital receiving incoherent scatter radar in Sanya (18.3°N, 109.6°E). The radar frequency band is from 430 to 450 MHz. The Sanya site is a low latitude station in China dedicated for ionospheric investigation. Meanwhile, SYISR is also suitable for detecting a wide range of space debris because of its high power and flexible beam steering ability. In this paper, we first calculate the detectable lower limit size of space debris with respect to integration time and range based on SYISR parameters through theoretical simulation. Then, we selected several typical space debris, with a size near the theoretical detectable lower limit, to perform the experiment. We found that the estimated radar cross section versus range accorded well with the theoretical curve, which confirmed our simulation. Specifically, the detectable lower limit size of space debris is ∼8 cm in a range of 1,000 km given a threshold signal‐to‐noise ratio of 14 dB. This value decreases to ∼3 cm if a 200‐ms coherent integration is implemented. We further performed several experiments on objects with different inclinations using signals with 0.3 and 4 MHz under both static staring and tracking modes. In comparison with the two‐line element file predicted raw orbit, the tracking error of 0.3 and 4 MHz are 7 km and 400 m, respectively, without coherent integration in the processing. The study expands the function of the SYISR and should be beneficial to our ionospheric data inversion given the frequent occurrence of space debris around the SYISR.

Regulation of sensory response students with disabilities of universities the process of inclusive physical education

The purpose of the article is to reveal the impact and effectiveness of inclusive physical education of students with disabilities. Research methods used: theoretical analysis, synthesis, systematization, generalization of data from scientific-methodical and special literature, pedagogical experiment, pedagogical testing, mathematical methods of processing digital arrays, comparative-statistical method, system-functional analysis. The results. Based on the results of the search activity, we received data indicating the following. Positive changes in the indicators of the experimental group students in all studied parameters of sensorimotor response were established, which testify to the improvement of the functional state of the central nervous system in the students of the experimental group after the end of the experiment. The result of the purposeful correction of the inclusive physical education of students with disabilities was that the positive dynamics of the coefficient of mental performance at the end of the study among the students of the experimental group was within 15 %. According to the integrative assessment of all studied parameters, it can be stated that after the end of the experiment, there is a general tendency to increase the results of the test tasks, which were at an average level in the vast majority of students of the experimental group (63.4 %). Conclusions. The results of the conducted research provide grounds for a conclusion regarding the possibility of purposeful correction employing inclusive physical education of the state of the sensorimotor reaction and its components and therefore have a comprehensive effect on the improvement of the main indicators of psychophysiological functions: the final data of the empirical experiment proved the effectiveness of the innovations introduced in the inclusive physical education of students with disabilities.

A 7.4-Bit ENOB 600 MS/s FPGA-Based Online Calibrated Slope ADC without External Components.

A slope analog-to-digital converter (ADC) amenable to be fully implemented on a digital field programmable gate array (FPGA) without requiring any external active or passive components is proposed in this paper. The amplitude information, encoded in the transition times of a standard LVDS differential input—driven by the analog input and by the reference slope generated by an FPGA output buffer—is retrieved by an FPGA time-to-digital converter. Along with the ADC, a new online calibration algorithm is developed to mitigate the influence of process, voltage, and temperature variations on its performance. Measurements on an ADC prototype reveal an analog input range from 0.3 V to 1.5 V, a least significant bit (LSB) of 2.6 mV, and an effective number of bits (ENOB) of 7.4-bit at 600 MS/s. The differential nonlinearity (DNL) is in the range between −0.78 and 0.70 LSB, and the integral nonlinearity (INL) is in the range from −0.72 to 0.78 LSB.

Development of the Sanya Incoherent Scatter Radar and Preliminary Results

AbstractLed by the Institute of Geology and Geophysics, Chinese Academy of Sciences, we have built a brand‐new modular active digital phased array, with all solid‐state transmission and digital receiving incoherent scatter radar (ISR) in Sanya (18.3°N, 109.6°E), a station in low latitude China called Sanya ISR (SYISR) since 2015. The development of SYISR involved the indoor design and development of key components, an outdoor prototype test, and the production and debugging of the entire array. The unique features of SYISR include a single‐channel directly connected T/R unit and antenna, a radar array monitoring and calibration network, environmental adaptability design and open architecture. The entire radar has 4,096 channels and 5,930 modules in total. All the technical indices, mainly including a >2 MW peak power, a 43 dBi antenna gain and a <120 K noise temperature, either meet or are superior to the designed value through an independent evaluation. Waveforms of single pulse, linear frequency modulation, Barker code, long pulse and alternating code have been implemented to meet multiple purposes. Four observational modes for ionospheric experiments, including zenith stare, perpendicular to geomagnetic field, meridian scan, and all sky scan, have been developed. We have implemented time domain decoding, frequency domain decoding, and statistical inversion methods in calculating the autocorrelation function and power spectra in signal processing. The preliminary experimental results on ionospheric parameters, plasma lines, irregularities and hard targets are reasonable and encouraging, which greatly enhances our confidence in achieving our scientific goals in the future.

Digital single-photon-avalanche-diode arrays for time-of-flight Thomson scattering diagnostics.

The collection optics of Thomson scattering systems for plasma devices are designed with maximum possible étendue to keep the required laser energy low. If the spatial resolution along the laser beam is performed by a time-of-flight method, then the detectors, in addition to a large sensitive area, must offer a high frequency bandwidth. Up until now, only microchannel-plate photomultipliers meet these requirements. Here, we investigate the potential use of digital avalanche photodiode arrays operated in the Geiger mode as alternative detectors. In this mode of operation, each array will serve as a fast, sensitive detector. The use of these detectors will lead to significant improvements of the Thomson scattering diagnostic. Most important of these will be a better spatial resolution, down to about 2cm without deconvolution. Furthermore, the lifetime of the detectors will be increased; the detectors will cover the whole blue wing of the scattered spectrum when using a single wavelength laser, and this will enable measurements of electron temperature and density profiles at kHz repetition rates.

Real-Time Adaptive Dwell Scheduling for Digital Array Radar Based on Virtual Dynamic Template

According to the characteristics of signal processing in digital array radar (DAR), an adaptive dwell scheduling algorithm based on the virtual dynamic template is proposed, where a general pulse interleaving method with the overlap of receiving durations is involved. The virtual dynamic template is introduced to realize the general pulse interleaving among tracking tasks, where the tracking tasks with different numbers and repetition intervals of pulses may be interleaved under the time and energy constraints. The proposed dwell scheduling algorithm is a perfect combination of adaptive dwell scheduling technique and novel pulse interleaving based on the virtual dynamic template. It is developed based on the task model with multiple pulses and can realize real-time dwell scheduling, therefore, can be used in an actual radar system. Furthermore, to improve the efficiency of the proposed dwell scheduling algorithm, the efficient version of it is given. Simulation results demonstrate that the proposed algorithms can improve the scheduling performance effectively. Furthermore, the scheduling performance and efficiency can be balanced easily with the control of the utilization ratio threshold in the proposed efficient algorithm.

Single Escherichia coli bacteria detection using a chemiluminescence digital microwell array chip

Rapid and sensitive Escherichia coli (E. coli) detection is important in determining environmental contamination, food contamination, as well as bacterial infection. Conventional methods based on bacterial culture suffer from long testing time (24 h), whereas novel nucleic acid-based and immunolabelling approaches are hindered by complicated operation, the need of complex and costly equipment, and the lack of differentiation of live and dead bacteria. Herein, we propose a chemiluminescence digital microwell array chip based on the hydrolysis of 6-Chloro-4-methylumbelliferyl-β-D-glucuronide by the β-D-glucuronidase in E. coli to achieve fast single bacterial fluorescence detection. Taking the advantage of the picoliter microwells, single bacteria are digitally encapsulated in these microwells, thus the accurate quantification of E. coli can be realized by counting the number of positive microwells. We also show that the chemiluminescence digital microwell array chip is not affected by the turbidity of the test samples as well as the temperature. Most importantly, our method can differentiate live and dead bacteria through bacterial proliferation and enzyme expression, which is confirmed by detecting E. coli after pH and chlorination treatment. By comparing with the standard method of plate counting, our method has comparable performance but significantly reduces the testing time from over 24 h–2 h and 4 h for qualitative and quantitative analysis, respectively. In addition, the microfluidic chip is portable and easy to operate without external pump, which is promising as a rapid and on-site platform for single E. coli analysis in water and food monitoring, as well as infection diagnosis.

Differentially Expressed Inflammation-Regulating MicroRNAs in Oligoarticular Juvenile Idiopathic Arthritis.

To evaluate microRNA expression in synovial fluid (SF), plasma, and leukocytes from patients with juvenile idiopathic arthritis (JIA). MicroRNA expression in pooled JIA plasma and SF was assessed by absolute quantitative droplet digital PCR array. The results were validated in individual patient samples. MicroRNA content in leukocytes and extracellular vesicles was evaluated by real-time PCR in JIA blood and SF. Blood microRNA expression was compared with healthy controls (HCs). Principal component analysis was used to profile JIA plasma and SF microRNAs, and the potential biological consequences of microRNA dysregulation were investigated by pathway analysis. MiR-15a-5p and miR-409-3p levels were higher in JIA plasma than in HC plasma. JIA SF contained elevated levels of miR-21-5p, miR-27a-3p, miR-146b-5p, miR-155-5p, and miR-423-5p, and decreased miR-192-5p and miR-451a, compared to JIA plasma. Extracellular vesicle analysis demonstrated variable encapsulation among selected microRNAs, with only miR-155-5p being represented substantially in extracellular vesicles. SF leukocytes also had higher expression of miR-21-5p, miR-27a-3p, miR-146b-5p, and miR-155-5p, and lower expression of miR-409-3p and miR-451a, relative to blood. No differences were observed between JIA and HC blood leukocytes. Clusters of microRNAs were commonly altered in JIA joint fluid and leukocytes compared to JIA blood samples. In silico analysis predicted that differentially expressed microRNAs in JIA target the transforming growth factor (TGF)-β pathway. The expression of multiple microRNAs is dysregulated in JIA both locally and systemically, which may inhibit the TGF-β pathway. These findings advance our knowledge of JIA immunopathogenesis and may lead to the development of targeted therapies.

Historical Perspectives, State of Art and Research Trends of SPAD Arrays and Their Applications (Part II: SPAD Arrays)

The ability to detect single photons is becoming an enabling key capability in an increasing number of fields. Indeed, its scope is not limited to applications that specifically rely on single photons, such as quantum imaging, but extends to applications where a low signal is overwhelmed by background light, such as laser ranging, or in which faint excitation light is required not to damage the sample or harm the patient. In the last decades, SPADs gained popularity with respect to other single-photon detectors thanks to their small size, possibility to be integrated in complementary metal-oxide semiconductor processes, room temperature operability, low power supply and, above all, the possibility to be fast gated (to time filter the incoming signal) and to precisely timestamp the detected photons. The development of large digital arrays that integrates the detectors and circuits has allowed the implementation of complex functionality on-chip, tailoring the detectors to suit the need of specific applications. This review proposes a complete overview of silicon SPADs characteristics and applications. In the previous Part I, starting with the working principle, simulation models and required frontend, the paper moves to the most common parameters adopted in literature for characterizing SPAD performance and describes single pixels applications and their performance. In this Part II, the focus is posed on the development of SPAD arrays, presenting some of the most notable examples found in literature. The actual exploitation of these designs in real applications (e.g., automotive, bioimaging and radiation detectors) is then discussed.

Historical Perspectives, State of art and Research Trends of Single Photon Avalanche Diodes and Their Applications (Part 1: Single Pixels)

The ability to detect single photons is becoming an enabling key capability in an increasing number of fields. Indeed, its scope is not limited to applications that specifically rely on single photons, such as quantum imaging, but extends to applications where a low signal is overwhelmed by background light, such as laser ranging, or in which faint excitation light is required not to damage the sample or harm the patient. In the last decades, SPADs gained popularity with respect to other single-photon detectors thanks to their small size, possibility to be integrated in Complementary Metal-Oxide Semiconductor processes, room temperature operability, low power supply and, above all, the possibility to be fast gated (to time filter the incoming signal) and to precisely timestamp the detected photons. The development of large digital arrays that integrates the detectors and circuits has allowed the implementation of complex functionality on-chip, tailoring the detectors to suit the need of specific applications. This review proposes a complete overview of silicon SPADs characteristics and applications. In this Part I, starting with the working principle, simulation models and required frontend, the paper moves to the most common parameters adopted in literature for characterizing SPADs, and describes single pixels applications and their performance. In the next Part II, the focus is then posed on the development of SPAD arrays, presenting some of the most notable examples found in literature. The actual exploitation of these designs in real applications (e.g., automotive, bioimaging and radiation detectors) is then discussed.

Study of digital diagram formation for optimum interference and noise reduction in antenna arrays of different shapes with directional radiators

In the paper the digital beamforming is examined in azimuth and elevation, which allows more accurate formation of nulls and maximum of the radiation pattern. The minimum variance distortionless response beamformer, the sample matrix inversion algorithm using regularization, and the null steering algorithms at the output of cylindrical, hemispherical and planar lattices are considered. The ratio of the useful signal power to the active interference plus noise resulting power and the bit error ratio at the output of digital antenna arrays are estimated depending on the directivity of the antenna elements and the number of averaging samples. It has been established that a hemispherical antenna array can significantly increase the transmission reliability in comparison with the considered ones, which will reduce the computational load without using complicated diagramming algorithms.