A New Method to Investigate InGaAsP Single-Photon Avalanche Diodes Using a Digital Sampling Oscilloscope

A near-infrared single-photon detection system is established by using pigtailed InGaAs/InP avalanche photodiodes. With a 50GHz digital sampling oscilloscope, the function and process of gated-mode （Geiger-mode） single-photon detection are intuitionally demonstrated for the first time. The performance of the detector as a gated-mode single-photon counter at wavelengths of 1310 and 1550nm is investigated. At the operation temperature of 203K,a quantum efficiency of 52% with a dark count probability per gate of 2.4 × 10 ^-3 ,and a gate pulse repetition rate of 50kHz are obtained at 1550nm. The corresponding parameters are 43%, 8.5 × 10^-3 , and 200kHz at 238K.

Digital arc welding power supply based on real-time operating system

A digital arc welding power supply was designed with the advanced reduced instruction set computer machine （ARM） and embedded real-time multi-task operating system micro C/OS- Ⅱ. The ARM, with its powerful calculating speed and complete peripheral equipments, is very suitable to work as the controller of the digital power supply. The micro C/OS- Ⅱ transplanted in ARM, helps to improve the respondent speed against various welding signals, as well as the reliability of the controlling software. The welding process consists of nine tasks. The tasks of great significance on reliability of the welder, for example, the A/D conversion of current and voltage, enjoy top priority. To avoid simultaneous-sharing on A/D converter and LCD module, two semaphores are introduced in to ensure the smooth performance of the welding power supply. Proven by experiments ,the ARM and the micro C/OS- Ⅱ can greatly improve both the respondent speed and the reliability of the digital welder.

Real-Time Discrete Adaptive Control of Robot Arm Based on Digital Signal Processing

A discrete model reference adaptive controller of robot arm is obtained by integrating the reduced dynamic model of robot, model reference adaptive control （MRAC） and digital signal processing （DSP） computer system into an electromechanical system. With the DSP computer system, the control signal of each joint of the robot arm can be processed in real time and independently. The simulation and experiment results show that with the control strategy, the robot achieved a good trajectory following precision, a good decoupling performance and a high real-time adaptivity.

A Portable Multi-functional Real-time Digital Simulator Dedicated to Protective Relay Testing

The paper intfoduces a PC-DSP based real-time digital simulator which is portable in size and aimed at the closed-loop testing of various types of protective relays for their design and application. The simulator can be widely used in not only concerning utilities but also manufacturers and research / certification institutes because of its many functions. The hardware architecture and software implementation of the simulator are described. The main features and functions of the simulator are also

Application of droplet digital PCR in detection of seed-transmitted pathogen Acidovorax citrulli

Bacterial fruit blotch caused by Acidovorax citrulli is a serious threat to cucurbit industry worldwide.The pathogen is seedtransmitted,so seed detection to prevent distribution of contaminated seed is crucial in disease management.In this study,we adapted a quantitative real-time PCR(qPCR)assay to droplet digital PCR(ddPCR)format for A.citrulli detection by optimizing reaction conditions.The performance of ddPCR in detecting A.citrulli pure culture,DNA,infested watermelon/melon seed and commercial seed samples were compared with multiplex PCR,qPCR,and dilution plating method.The lowest concentrations detected(LCD)by ddPCR reached up to 2 fg DNA,and 102 CFU mL–1 bacterial cells,which were ten times more sensitive than those of the qPCR.When testing artificially infested watermelon and melon seed,0.1%infestation level was detectable using ddPCR and dilution plating method.The 26 positive samples were identified in 201 commercial seed samples through ddPCR,which was the highest positive number among all the methods.High detection sensitivity achieved by ddPCR demonstrated a promising technique for improving seed-transmitted pathogen detection threshold in the future.

Establishment and Application of Digital RT-PCR Assay for Detection of Avian Influenza Virus H9 Subtype

A digital RT-PCR method for rapid detection of H9 subtype influenza was established by comparing the two methods of digital RT-PCR and real-time quantitative RT-PCR. The sensitivity, specificity and reproducibility of the two methods for H9 were determined by gradient dilution using the same pair of primers and probes. Both methods were able to detect 104 times diluted H9 pathogens, while digital RT-PCR could detect H9 in single droplets, and its sensitivity was higher than real-time quantitative RT-PCR. At the same time, the specificities of both methods were very strong, with no amplification reactions for H3N2, H4N2, H6N2. The reproducibility of the two methods were also good. Digital RT-PCR has a higher sensitivity than real-time quantitative RT-PCR and could play an important role in the rapid detection of H9 subtype influenza virus.

REAL-TIME LICENSING MANAGEMENT OF SECURE MULTIMEDIA CONTENT DELIVE RY

Media Commerce is now becoming a new trend which results fr om faster development of network bandwidth and high availability of multimedia t echnologies, how to protect media content from being used in a right-violated w ay is one of most important issues to take into account. In this paper, a novel and efficient authorization and authentication Digital Rights Management (DRM) s chema is proposed firstly for secure multimedia delivery, then based on the sche ma, a real-time digital signature algorithm built on Elliptic Curve Cryptograph y (ECC) is adopted for fast authentication and verification of licensing managem ent, thus secure multimedia delivery via TCP/RTP can efficiently work with real -time transaction response and high Quality of Service (QoS) . Performance eval uations manifest the proposed schema is secure, available for real-time media s tream authentication and authorization without much effected of QoS. The propose d schema is not only available for Client/Server media service but can be easily extended to P2P and broadcasting network for trusted rights management.

Real-time digital data of international passengers will shine in the precaution of epidemics

International movement plays an important role in spatial spread of infectious diseases.Here,we share two successful COVID-19 interventions based on real-time digital information collected from international passengers,which have been performed in Greece and China respectively.Both of the interventions demonstrated good performance and showed the potential of real-time digital data in containing the spread.However,several key points should not be ignored when we promote similar strategies.

用数字示波器探究光磁共振实验中反常共振信号的机理

本文根据拟合得到的gF因子大小,确定了光磁共振实验中的反常共振信号;用数字示波器测量了反常共振射频信号的频谱,计算了反常共振射频信号各高次谐波的大小;通过线性拟合,得到了正常共振信号幅度与射频信号幅度的关系。利用此关系,计算了各高次谐波产生的反常共振信号大小,计算结果与测量值基本一致。频率计连接射频信号源后,射频信号波形和频谱发生明显变化,反常共振信号随着射频信号频谱的变化发生相应改变,进一步证明了反常共振信号由射频信号的高次谐波共振所引起。这些结果表明,用数字示波器探究光磁共振实验中反常共振信号的机理不仅可行,还能定量估算和预测射频信号波形对反常共振信号大小的影响。

数字示波器相频特性的计量评价

针对数字示波器相频特性校准中,响应波形与激励信号之间相位差获取的难点问题,提出一种借助于脉冲沿幅度触发功能特性的方法,通过设定触发参量与激励信号幅度关系,固定与响应信号波形相对应的激励信号的相位点,从而精确获取被测数字示波器的相移特性,并统一了不同频率下相移特性的参考相位点,顺利获得数字示波器相频响应特性曲线。在一组实验中,验证了所述方法的有效性和可行性,可用于数字示波器相频响应特性的测量评价。

数字示波器中FPGA间高速信号传输同步方法

数据采集系统是数字示波器(DSO)的核心组成单元,随着示波器带宽采样率的逐步提升,单片模数转换器(ADC)+现场可编辑门控阵列(FPGA)的架构难以满足超高速以及多通道的应用场景,因此,高端示波器中数据采集系统普遍采用“主从”FPGA控制架构。在该架构下,多个FPGA之间信号的同步传输是实现采集系统的同步和精确采集的重要前提。针对多FPGA板卡之间的信号同步传输问题,提出了一种FPGA之间高速信号同步传输的方法,借助FPGA的IODELAY单元,通过测试数据训练找到最稳定的同步传输区间,实现多FPGA之间的同步传输。在自研的数字示波器上的实验表明,该方法能够有效实现FPGA之间高速信号的同步传输。

基于示波器的热电偶响应时间采集系统分析

鉴于数字示波器在热电偶响应时间测试中的广泛应用,以K型热电偶为例,采用校验仪模拟热电偶的输出热电势,实验研究了数字示波器测量热电势误差,分析了基于热电势瞬态变化曲线通过作图法获得热电偶响应时间的误差。结果表明,在0~100℃和0~1000℃范围内,数字示波器测量热电势的绝对值偏差较大,但是重复性和线性良好。在温度阶跃量的50%处(50℃和700℃),热电势瞬态曲线与温度曲线的偏差分别为0.5℃和2.1℃,约为温度阶跃量的1%。因而,基于热电势瞬态变化曲线通过作图法获得热电偶响应时间的方法误差较小,通常约为温度波动产生的误差。

Comprehensive and personalized approach is a critical area for developing remote cardiac rehabilitation programs

In the evolving landscape of cardiac rehabilitation(CR),adopting digital technologies,including synchronous/real-time digital interventions and smart applications,has emerged as a transformative approach.These technologies offer realtime health data access,continuous vital sign monitoring,and personalized educational enhanced patient self-management and engagement.Despite their potential benefits,challenges and limitations exist,necessitating careful consideration.Synchronous/real-time digital CR involves remote,two-way audiovisual communication,addressing issues of accessibility and promoting home-based interventions.Smart applications extend beyond traditional healthcare,providing real-time health data and fostering patient empowerment.Wearable devices and mobile apps enable continuous monitoring,tracking of rehabilitation outcomes,and facilitate lifestyle modifications crucial for cardiac health maintenance.As digital CR progresses,ensuring patient access,equitable implementation,and addressing the digital divide becomes paramount.Artificial intelligence holds promise in the early detection of cardiac events and tailoring patient-specific CR programs.However,challenges such as digital literacy,data privacy,and security must be addressed to ensure inclusive implementation.Moreover,the shift toward digital CR raises concerns about cost,safety,and potential depersonalization of therapeutic relationships.A transformative shift towards technologically enabled CR necessitates further research,focusing not only on technological advancements but also on customization to meet diverse patient needs.Overcoming challenges related to cost,safety,data security,and potential depersonalization is crucial for the widespread adoption of digital CR.Future studies should explore integrating moral values into digital therapeutic relationships and ensure that digital CR is accessible,equitable,and seamlessly integrated into routine cardiac care.Theoretical frameworks that accommodate the dynamic quality of real-time monitoring and feedback feature of digital CR interventions should be considered to guide intervention development.

A droplet digital PCR method(ddPCR)for sensitive detection and quantification of Carassius auratus herpesvirus(CaHV)

Carassius auratus herpesvirus(CaHV)is a pathogen isolated from crucian carp(Carassius auratus)associated with high mortality.A diagnosis method that can detect the virus at an early stage,specifically and accurately,is an urgent requirement for the prevention of CaHV transmission.In the present study,a droplet digital PCR(ddPCR)method based on the tumor necrosis factor receptor(TNFR)gene was established to detect and quantify CaHV DNA with high specificity and no cross-reactions with other aquatic viruses.Skin mucus samples were collected from infected crucian carp from Day 1–8 after infection,and positive amplification was detected on the first day by ddPCR(0.54 copies/μL),whereas the presence of CaHV was not detected by routine PCR until Day 6.Tissue DNA was then collected from the head kidney of 20 fishes which were injected with CaHV and died during the experiment.The five negative samples checked by routine PCR were detected by ddPCR and real-time PCR(qPCR),respectively.The results showed that the positive detection rate of ddPCR(100%)was higher than that of qPCR(40%).The detection limit of the ddPCR was found to be 0.52 copies/μL,which was much lower than the 50.12 copies/μL determined by qPCR.Overall,ddPCR offers a highly promising diagnosis method for the absolute quantification of CaHV in carrier fish and samples from the skin mucus and head kidney with low viral concentrations.

Measurement of soil electrical conductivity based on direct digital synthesizer(DDS)and digital oscilloscope

A soil electrical conductivity(EC)measurement system based on direct digital synthesizer(DDS)and digital oscilloscope was developed.The system took the“current-voltage four-electrode method”as the design principal and adopted a six-pin structure of the probe,two center pins to measure the soil EC in shallow layer,two outside pins to measure the soil EC in deep layer,and two middle pins for inputting the driving current.A signal generating circuit using DDS technology was adopted to generate sine signals,which was connected with the two middle pins.A digital oscilloscope was used to record and store the two soil output signals with noises in microseconds,which were from the two center pins and two outside pins,respectively.Then a digital bandpass filter was used to filter the soil output signals recorded by the digital oscilloscope.Compared with the traditional analog filter circuit,the digital filter could filter out the noises of all frequency except for the frequency of the excitation source.It could improve the effect of filtering and the accuracy of the soil EC measurement system.The DDS circuit could provide more stable sine signals with larger amplitudes.The use of digital oscilloscope enables us to analyze the soil output signals in microseconds and measure the soil EC more accurately.The new soil EC measurement system based on DDS and digital oscilloscope can provide a new effective tool for soil sensing in precision agriculture.

Micro-droplet Digital Polymerase Chain Reaction and Real-Time Quantitative Polymerase Chain Reaction Technologies Provide Highly Sensitive and Accurate Detection of Zika Virus

The establishment of highly sensitive diagnostic methods is critical in the early diagnosis and control of Zika virus(ZIKV)and in preventing serious neurological complications of ZIKV infection. In this study, we established micro-droplet digital polymerase chain reaction(ddPCR) and real-time quantitative PCR(RT-qPCR) protocols for the detection of ZIKV based on the amplification of the NS5 gene. For the ZIKV standard plasmid, the RT-qPCR results showed that the cycle threshold(Ct) value was linear from 10~1 to 10~8 copy/l L, with a standard curve R^2 of 0.999 and amplification efficiency of 92.203%;however, a concentration as low as 1 copy/l L could not be detected. In comparison with RT-qPCR, the dd PCR method resulted in a linear range of 10~1–10~4 copy/l L and was able to detect concentrations as low as 1 copy/l L. Thus, for detecting ZIKV from clinical samples, RT-qPCR is a better choice for high-concentration samples(above 10~1 copy/l L),while ddPCR has excellent accuracy and sensitivity for low-concentration samples. These results indicate that the ddPCR method should be of considerable use in the early diagnosis, laboratory study, and monitoring of ZIKV.

Augmented virtual environment: fusion of real-time video and 3D models in the digital earth system

An Augmented virtual environment(AVE)is concerned with the fusion of real-time video with 3D models or scenes so as to augment the virtual environment.In this paper,a new approach to establish an AVE with a wide field of view is proposed,including real-time video projection,multiple video texture fusion and 3D visualization of moving objects.A new diagonally weighted algorithm is proposed to smooth the apparent gaps within the overlapping area between the two adjacent videos.A visualization method for the location and trajectory of a moving virtual object is proposed to display the moving object and its trajectory in the 3D virtual environment.The experimental results showed that the proposed set of algorithms are able to fuse multiple real-time videos with 3D models efficiently,and the experiment runs a 3D scene containing two million triangles and six real-time videos at around 55 frames per second on a laptop with 1GB of graphics card memory.In addition,a realistic AVE with a wide field of view was created based on the Digital Earth Science Platform by fusing three videos with a complex indoor virtual scene,visualizing a moving object and drawing its trajectory in the real time.

A fast digital timing and analysis system based on real-time dCFD technique for nuclear physics experiments

In this paper a fast digital real-time spectrometer was developed for timing and analysis of nuclear pulse signals. The hardware system design and algorithm implementation with field-programming gate array （FPGA） and digital signal processor （DSP） were introduced. The performance of the digital constant fraction discrimination （dCFD） platform was experimentally tested with Agilent 80 MHz function/arbitrary waveform generator and LaC13：Ce3＋ scintillator detector for 22Na positron annihilation gamma spectroscopy. The amplitude and time information of ＂/photon was online obtained. The energy resolution could be 5.525% and the timing resolution 293.75 ps, the system error estimation of dCFD approach was also studied. The results showed that this spectrometer achieved a timing resolution close to that of traditional CFD timing resolution with a more sim- plified system structure.

TAD-Net:An approach for real-time action detection based on temporal convolution network and graph convolution network in digital twin shop-floor[version 1;peer review:2 approved]

Background:Intelligent monitoring of human action in production is an important step to help standardize production processes and construct a digital twin shop-floor rapidly.Human action has a significant impact on the production safety and efficiency of a shop-floor,however,because of the high individual initiative of humans,it is difficult to realize real-time action detection in a digital twin shop-floor.Methods:We proposed a real-time detection approach for shop-floor production action.This approach used the sequence data of continuous human skeleton joints sequences as the input.We then reconstructed the Joint Classification-Regression Recurrent Neural Networks(JCR-RNN)based on Temporal Convolution Network(TCN)and Graph Convolution Network(GCN).We called this approach the Temporal Action Detection Net(TAD-Net),which realized real-time shop-floor production action detection.Results:The results of the verification experiment showed that our approach has achieved a high temporal positioning score,recognition speed,and accuracy when applied to the existing Online Action Detection(OAD)dataset and the Nanjing University of Science and Technology 3 Dimensions(NJUST3D)dataset.TAD-Net can meet the actual needs of the digital twin shop-floor.Conclusions:Our method has higher recognition accuracy,temporal positioning accuracy,and faster running speed than other mainstream network models,it can better meet actual application requirements,and has important research value and practical significance for standardizing shop-floor production processes,reducing production security risks,and contributing to the understanding of real-time production action.