Synchronization Technique Research Articles

A high-speed frequency adaptive grid synchronization technique for single-phase inverter under distorted grid conditions

A high-speed frequency adaptive grid synchronization technique for single-phase inverter under distorted grid conditions

Enhanced Grid Synchronization Technique Based on Frequency Detector for Three-Phase Systems

An adaptive cascaded delayed signal cancellation (CDSC) method relying on a simple frequency detector is combined with a third-order function for three-phase grid synchronization application. In this article, the proposed synchronization technique shows a high degree of insensitivity to harmonics at both nominal and off-nominal frequency environments. When compared to a similar method relying on adaptive CDSC and phase-locked loop (CDSC-PLL), the proposed technique generates alike results but demands less computational effort due to avoiding real-time evaluation of computationally demanding trigonometric functions and square root operation. Moreover, unlike the CDSC-PLL method, the proposed one eliminates the interdependent loops exist between the phase and frequency estimation, thus a simpler tuning process is achieved. In addition, the proposed method stays away from the tuning of the loop filter in the PLL by removing the phase loop. The usefulness of the proposed method is established by both simulation and experimental results.

Random Sampling-and-Averaging Techniques for Single-Photon Arrival-Time Detections in Quantum Applications: Theoretical Analysis and Realization Methodology

A random sampling-and-averaging (RSA) technique based on stochastic Monte Carlo methods is described in this paper for enhancing the accuracy of single-photon arrival-time measurements down to sub-picosecond ranges in emerging quantum applications. The theoretical variances of both synchronous and asynchronous RSA techniques are presented in the mathematical formats and experimentally verified by the Monte Carlo simulations. Meanwhile, the methodology of converting the mathematical models into an almost all-digital low-power integrated-circuit is elaborated by a circuit-level example with the instruction of setting circuit parameters. Along with the superior measurement resolution, scalable dynamic ranges, high linearity, high noise immunity, and low power/area consumption, the primary limitation of the RSA techniques has also been addressed for the forthcoming conversion-rate enhancement techniques.

Evaluation of transformer insulation with different PD methods using a synchronous multi-channel technique

Evaluation of transformer insulation with different PD methods using a synchronous multi-channel technique

Research on synchronous measurement technique of temperature and deformation fields using multispectral camera with bilateral telecentric lens

The hot-section parts easily occur the creep-fatigued interaction under the condition of mechanical-thermal coupled load during the period of service, which may lead to the damage of the parts, and therefore, the measurement and characterization of thermal-deformed fields of the parts are important to understand its damage process. Aiming at relevant demand, the bilateral telecentric-multispectral imaging system was established, the research of synchronous measurement technique of the temperature and deformation fields was developed. On the one hand, the measurement technology for surface temperature of the object was developed using the two-color images captured by the multispectral camera with bilateral telecentric lens and combined with colorimetric method. On the other hand, the 2D-DIC measurement technique of the multispectral camera was developed by conducting digital image correlation analysis using the blue light images before and after deformation, which can measure the high temperature deformation field of the object (the blue light images were filtered by multispectral camera). Results showed that the bilateral telecentric lens is used to replace the ordinary optical lens for imaging, which can effectively eliminate the distortion of the multispectral imaging system. Since the temperature measurement process of this measurement system is little affected by the emissivity of the object, therefore, it has excellent robustness. The thermal expansion coefficients of the nickel alloys are evaluated at the temperature ranges of 700–1000 ℃, indicating this system can achieve the synchronous and precise measurement of the temperature and deformation fields of the object.

A Delay-Based Frequency Estimation Scheme for Speed-Sensorless Control of Induction Motors

The use of costly speed sensors challenges the overall system reliability in induction motor drives. Hence, speed-sensorless control techniques are desired in high-performance induction motors, where estimating the motor speed is of importance. Distinctive advantages, e.g., structural and control simplicity and acceptable performance, have pushed the synchronization technique (ST)-based estimation schemes popular for motor drives. However, in many ST-based schemes, their performance may be degraded during acceleration and deceleration. To address this, a delay-based frequency estimation (DFE) scheme is explored for speed-sensorless control of induction motors in this article. More specifically, speed estimation in the proposed DFE scheme is achieved by using the estimated rotor flux and its delay signals. Additionally, disturbances like dc offsets are also considered, and thus a closed-loop flux observer is implemented in the proposed DFE scheme to maintain speed estimation. The performance of the proposed DFE scheme is investigated by experimental tests.

Dynamic compressive behavior of a single crystal nickel-base superalloy at ultra-high temperature: mechanism investigation with a modified electric synchronous SHPB technique

A novel experimental technique conducted at a modified automatic split Hopkinson pressure bar (SHPB) for measuring the dynamic compressive behavior at ultra-high temperature up to 1700 °C was developed. A bidirectional electric synchronous assembly system, two high-precision delay controllers and an automatic control mechanism were employed to automate each section in the whole experiment process with high precision and high reliability. The cold contact time (CCT) between specimen and loading bars can be accurately and stably controlled to be shorter than 5 ms and the effect of CCT on temperature distribution can be eliminated. Based on this automatic high-temperature SHPB technique, an experimental investigation into the responses of a new in-service single-crystal Nickel-base superalloy DD10 subjected to impact loading at high temperature was undertaken. The influence of strain rate and temperature on the flow behavior of DD10 was tested and analyzed over a wide range of strain rate (0.001/s-4000/s) and temperature (25°C–1200 °C). The high temperature has an evident effect on the flow stress, strain hardening and strain rate sensibility. An anomalous peak of stress in true stress–temperature curve can be found, and the peak temperature increases with strain rate increasing. Through the microstructural observation, the influence of strain rate and temperature on the compressive deformation and fracture mechanism was discussed. At the high temperature above 1000 °C, the shear deformation mechanism of both γ matrix phase and γ′ precipitate phase is the dominant deformation mechanism at high strain rate, instead of the rafting mechanism of γ′ precipitate phase of under quasi-static loading condition.

An optimal indoor trust-region PPP algorithm with constrain of homologous array pseudolite

Homologous array pseudolite with simple time synchronization technique can provide high-precision larger-area indoor location service with outdoor GNSS receiver, but this architecture is born with several drawbacks, such as poor geometry, larger linearization error and multi-path error caused by signal reflection, and indoor positioning with this homologous array pseudolite can easily lead to potential divergence. Besides, fluctuation of time-delay, error of phase center and potential multipath error break integer propriety of carrier phase ambiguity and can’t be ignored for indoor PPP (Precise Point Positioning). Under these constrictions, optimal ambiguity-float indoor PPP algorithm with trust region is proposed, and performance of this optimal algorithm with the modified Levenberg-Marquardt technique, which is designed to avoid potential divergence particularly for poor geometry, is assessed with simulation and observation filed experiment. Meanwhile, the domain factor affecting performance of PPP and mechanism of accumulative error when moving are analyzed. The experimental result reveals that: unavoidable inaccuracy of position of pseudolite transmitting antenna can cause larger error of carrier phase bias that can be larger than 0.105 cycles, and it along with fluctuation of hardware group delay and multi-path error will cause position error that can be larger than 0.12 for most cases, the indoor static and kinematic PPP can obtain a few centimeter and smooth trace respectively, and the accuracy of indoor positioning based on this optimal algorithm can be better than 0.1668 m even at the corner of experiment area with poor geometry. Still there is particular circumstance that accuracy of this algorithm can be larger than 0.5741 m due to serious accumulative error with less satellite available when moving, the mechanism for it is analyzed with relationship between error of position and measurement error and depicted as follows: when some satellites with cycle slip occurs, the accuracy of position determined will reduce greatly due to less satellite available particularly with indoor homologous array pseudolite. Afterwards, the error of the position determined will lead to error of carrier phase ambiguity biases, which will cause large biases of subsequent position determined.

Benefits of Fuzzy Logic on MPPT and PI Controllers in the Chain of Photovoltaic Control Systems

This paper presents a comparative study between two maximum power point tracking (MPPT) algorithms, the incremental conductance algorithm (InC) and the fuzzy logic controller (FLC). The two algorithms were applied to a low photovoltaic power conversion system, and they both use different PI controllers and grid synchronization techniques. Moreover, both InC and FLC methods have Clarke and Park Transformation. To some extent, the incremental conductance and fuzzy logic controller approaches are similar, but their control loops are different. Therefore, the InC has classic Proportional Integrative (PI) controllers with simple phase-locked loops (PLL). At the same time, the FLC works with fuzzy logic PI controllers linked with the Second Order Generalized Integrator (SOGI). The proposed techniques examine the solar energy conversion performance of the photovoltaic (PV) system under possible irradiance changes and constant temperature conditions. Finally, a performance comparison has been made between InC and FLC, which demonstrates the effectiveness of the fuzzy controller over the incremental conductance algorithm. FLC turns to convert photovoltaic power easily, decreasing fluctuations, and it offers a quick response to the variation of solar irradiance (shading effect). The simulation results show a superior performance of the controller with fuzzy logic, which helps the inverter convert over 99% of the power generated by the photovoltaic panels. In comparison, the incremental conductance algorithm converts around 80%.

An improved digital phase locked loop against adverse grid conditions

The phase-locked loop (PLL) is an essential synchronization technique to ensure stable operation and control of grid-connected converters. Nevertheless, under actual conditions, the grid voltage is often influenced by harmonics and frequency variation, resulting in unsatisfactory steady-state precision and dynamic performance of the PLL. Therefore, in this paper, an improved digital PLL (ID-PLL) including harmonics elimination module and angular frequency reference calculation module is proposed. The proposed ID-PLL can maintain steady-state precision and dynamic performance in the condition of voltage unbalance, voltage harmonics and voltage frequency variation. The influence of adverse grid voltage on PLL performance is analyzed in detail. The parameters design and discretization approach is presented accordingly. The effectiveness of the proposed approach is confirmed by compared experiments with DSOGI-PLL.

Time-resolved imaging of ultrasound waveform with synchronized laser illumination

We present a synchronous time delay technique to precisely control the illuminating laser pulses and the ultrasonic wave generation to visualize the ultrasound waveform through the Schlieren imaging method. The proposed time-resolved imaging technique offers the two-dimensional mapping of ultrasound waveform in a temporally evolved manner. The critical physical parameters, such as speed and spatial pulse length of ultrasonic waves, are visualized and calculated from image analysis. Our results suggest a protocol in characterizing ultrasound waveform, and it has the potential to reconstruct the acoustic field by accumulating the time-lapse waveforms.

Early scheduling on steroids: Boosting parallel state machine replication

State machine replication (SMR) is a standard approach to fault tolerance in which replicas execute requests deterministically and often serially. For performance, some techniques allow concurrent execution of requests in SMR while keeping determinism. Such techniques exploit the fact that independent requests can execute concurrently. A promising category of early scheduling solutions trades scheduling freedom for simplicity, allowing to expedite decisions during scheduling. This paper generalizes early scheduling and proposes a general method to schedule requests to threads, restricting scheduling overhead. Moreover, it explores improvements to the original early scheduling mechanism, namely the use of busy-wait synchronization and work-stealing techniques. We integrate early scheduling and its proposed improvements to a popular SMR framework. Performance results of the basic mechanism and its improvements are presented and compared to more classic approaches, where it is shown that early scheduling with our proposed enhancements can outperform the original early scheduling and other systems by a large margin in many scenarios.

Four dimensional hyperchaotic communication system based on dynamic feedback synchronization technique for image encryption systems

<span>This paper presents the design and simulation of a hyperchaotic communication system based on four dimensions (4D) Lorenz generator. The synchronization technique that used between the master/transmitter and the slave/receiver is based on dynamic feedback modulation technique (DFM). The mismatch error between the master dynamics and slave dynamics are calculated continuously to maintain the sync process. The information signal (binary image) is masked (encrypted) by the hyperchaotic sample x of Lorenz generator. The design and simulation of the overall system are carried out using MATLAB Simulink software. The simulation results prove that the system is suitable for securing the plain-data, in particular the image data with a size of 128×128 pixels within 0.1 second required for encryption, and decryption in the presence of the channel noise. The decryption results for gray and colored images show that the system can accurately decipher the ciphered image, but with low level distortion in the image pixels due to the channel noise. These results make the proposed cryptosystem suitable for real time secure communications.</span>

Rooftop Garden and Lighting Automation by the Internet of Things (IoT)

The Internet of Things (IoT) enables individuals to easily operate more than only digital things through the internet using a user-friendly GUI. The researchers are particularly interested in the use of IoT for household and industrial automation, as well as the monitoring of a variety of physical properties over the internet. This internet of things project showcased current system upgrades as well as creative solutions to specific issues. The Internet of Things (IoT) is a technology that allows for continuous monitoring of wirelessly linked objects by utilizing wireless sensor networks, nanostructures, and scalability.The Internet of Things is made up of many physical objects that connect with one another. It would allow users to approach numerous applications in unique ways, such as smart homes and smart agriculture, by enabling seamless connection between virtual and actual equipment, assuring dialogues at any time and from any location. The user may examine the status of any network resources.The IoT being used has its own network plan, allowing it to observe the state of embedded devices and take appropriate action by passing instructions regulating the objects via the web server utilizing Internet connections.This project aimed to create a rooftop home gardening facility capable of synchronizing the utility grid with a moisture sensor and a water pump. We were able to effectively build the central notion of the synchronization technique and connect it to a mobile device through Bluetooth. Several tweaks and trial and error tactics were utilized to make this one function. We have just shown the procedure of synchronizing and switching approaches in this study.

Rooftop Garden and Lighting Automation by the Internet of Things (IoT)

The Internet of Things (IoT) enables individuals to easily operate more than only digital things through the internet using a user-friendly GUI. The researchers are particularly interested in the use of IoT for household and industrial automation, as well as the monitoring of a variety of physical properties over the internet. This internet of things project showcased current system upgrades as well as creative solutions to specific issues. The Internet of Things (IoT) is a technology that allows for continuous monitoring of wirelessly linked objects by utilizing wireless sensor networks, nanostructures, and scalability.The Internet of Things is made up of many physical objects that connect with one another. It would allow users to approach numerous applications in unique ways, such as smart homes and smart agriculture, by enabling seamless connection between virtual and actual equipment, assuring dialogues at any time and from any location. The user may examine the status of any network resources.The IoT being used has its own network plan, allowing it to observe the state of embedded devices and take appropriate action by passing instructions regulating the objects via the web server utilizing Internet connections.This project aimed to create a rooftop home gardening facility capable of synchronizing the utility grid with a moisture sensor and a water pump. We were able to effectively build the central notion of the synchronization technique and connect it to a mobile device through Bluetooth. Several tweaks and trial and error tactics were utilized to make this one function. We have just shown the procedure of synchronizing and switching approaches in this study.

Half-Sandwich Cyclometalated RhIII Complexes Bearing Thiolate Ligands: Biomolecular Interactions and In Vitro and In Vivo Evaluations.

A class of cyclometalated RhIII complexes [Cp*Rh(ppy)(SR)] bearing thiolate ligands, Cp* = pentamethylcyclopentadienyl, ppy = 2-phenylpyridinate, and R = pyridyl (Spy, 2), pyrimidyl (SpyN, 3), benzimidazolyl (Sbi, 4), and benzothiazolyl (Sbt, 5), were produced and identified by means of spectroscopic methods. The in vitro cytotoxicity of the RhIII compounds in three different human mortal cancerous cell lines (ovarian, SKOV3; breast, MCF-7; lung, A549) and a normal lung (MRC-5) cell line were evaluated, indicating the selectivity of these cyclometalated RhIII complexes to cancer cells. Complex 5, selected for in vivo experiment, has shown an effective inhibition of tumor growth in SKOV3 xenograft mouse model relative to control (p-values < 0.05 and < 0.01). Importantly, the outcomes of H&E (hematoxylin and eosin) staining and hematological analysis revealed negligible toxicity of 5 compared to cisplatin on a functioning of the main organs of mouse. Molecular docking, UV-vis, and emission spectroscopies (fluorescence, 3D fluorescence, synchronous) techniques were carried out on 1-5 to peruse the mechanism of the anticancer activities of these complexes. The obtained data help to manifest the binding affinity between the rhodium compounds and calf thymus DNA (CT-DNA) through the interaction by DNA minor groove and moderate binding affinity with bovine serum albumin (BSA), particularly with the cavity in the subdomain IIA. It can be concluded that the Rh-thiolate complexes are highly promising leads for the development of novel effective DNA-targeted anticancer drugs.

An Ultrasensitive Strand Displacement Signal Amplification-Assisted Synchronous Fluorescence Assay for Surface Proteins of Small Extracellular Vesicle Analysis and Cancer Identification

Small extracellular vesicles (sEVs), often known as exosomes, are expected to be a promising biomarker for the early diagnosis of cancer because they carry enriched proteins that originated from parent cells. Profiling surface proteins of sEVs offers non-invasive access for the early diagnosis of cancer. However, it remains challenging to simultaneously detect surface proteins of sEVs with desired sensitivity. Herein, a dual color DNA nanodevice based on toehold-mediated DNA strand displacement signal amplification and the synchronous fluorescence technique has been developed for simultaneous analysis of surface proteins of sEVs with high sensitivity. As for the DNA nanodevice-based system, the nanoconjugates of aptamer-magnetic beads can recognize surface proteins of sEVs and lead to the release of single-stranded DNA. Then, the released DNA can trigger toehold-mediated DNA strand displacement for signal amplification. In this system, a CD63 aptamer and MUC1 aptamer were used as recognition elements for the detection of surface proteins of sEVs isolated from cancer cells. Under the optimal conditions, the corresponding proteins of sEVs were simultaneously determined with ultrasensitivity by the synchronous fluorescence method. Also, the detection limits of sEVs by two surface proteins were 67 particles/μL by CD63 and 37 particles/μL by MUC1. Of note, the as-constructed method can be applied to recognize sEVs from different tumor cell lines (SGC7901, HepG2, and MCF-7 cells). Furthermore, the system has been successfully applied to precisely identify cancer patients from healthy people by serum analysis. The strategy demonstrates great potential applications in the early diagnosis of cancer.

On voice-over translation of documentaries in Iran: A synchronization perspective

ABSTRACT Voice-over is a mode of transfer in the audiovisual translation in which the original soundtrack is heard simultaneously in the background. The reason for the double-voice hearing is proof of the products’ authenticity and translators’ faithfulness to the target viewers. The technical factor of synchrony (adapting the length of the soundtrack, matching the original and target soundtracks, the soundtrack and visuals, and the soundtrack and body movements) raises the quality of voiced-over products. Voice-over is widely used in the translation of documentaries in many countries including Iran. The present study investigated documentary voice-over on Iran’s national television from an isochrony perspective seeking to examine to what extent the international isochrony standards are followed and where the Iranian voice-over profession stands. For this purpose, a documentary was selected and analyzed based on framework triangulated by the researchers. The results revealed that, in practice, voice-over narrators adhered strongly to synchronization techniques in most segments of the selected documentary. The study demonstrates that documentary voice-over translation techniques, particularly the synchronization principles, are frequently followed on Iran’s television, although with slight modifications they would even improve more.

Open Loop Synchronization Techniques Benchmarking for Distributed Energy Sources Connection

Synchronization is a crucial process in the operation of grid-connected distributed energy sources. Synchronization techniques are classified in closed-loop (CLS) and open-loop synchronization (OLS) techniques. Unlike the CLS technique, OLS techniques are recent and less known. This paper discusses a comparative analysis of the three prominent state-of-the-art OLS techniques. Accordingly, a benchmark model is proposed to systematically evaluate the performance of the OLS techniques under grid voltage disturbances such as harmonic distortions, voltage unbalance, DC offset, and low voltage ride through operation. Given the hardware resource utilization, the computational complexity and the execution time are also presented to judge the efficacy of the proposed model. Thus, engineers/or researchers can better understand the choice of hardware resources and the preferred dynamic performance of a synchronization scheme applied to control and protect a grid-tied power converter. Simulation and experimental results are presented and discussed to demonstrate the purpose of the proposed model.

Architectures and Synchronization Techniques for Distributed Satellite Systems: A Survey

Cohesive Distributed Satellite Systems (CDSSs) is a key enabling technology for the future of remote sensing and communication missions. However, they have to meet strict synchronization requirements before their use is generalized. When clock or local oscillator signals are generated locally at each of the distributed nodes, achieving exact synchronization in absolute phase, frequency, and time is a complex problem. In addition, satellite systems have significant resource constraints, especially for small satellites, which are envisioned to be part of the future CDSSs. Thus, the development of precise, robust, and resource-efficient synchronization techniques is essential for the advancement of future CDSSs. In this context, this survey aims to summarize and categorize the most relevant results on synchronization techniques for Distributed Satellite Systems (DSSs). First, some important architecture and system concepts are defined. Then, the synchronization methods reported in the literature are reviewed and categorized. This article also provides an extensive list of applications and examples of synchronization techniques for DSSs in addition to the most significant advances in other operations closely related to synchronization, such as inter-satellite ranging and relative position. The survey also provides a discussion on emerging data-driven synchronization techniques based on Machine Learning (ML). Finally, a compilation of current research activities and potential research topics is proposed, identifying problems and open challenges that can be useful for researchers in the field.