Synchronization Technique Research Articles

Fast Kalman filter synchronization algorithm for cooperative synchronization in time sensitive networks

Clock synchronization is crucial in time-sensitive networks (TSN) to ensure the normal operation of devices. However, traditional synchronization techniques face challenges such as the accumulation of synchronization errors over multiple hops and slow synchronization speed, which hinder the development of large-scale and multi-hop TSN. In this paper, we propose a cooperative synchronization scheme based on two-way timestamp exchange to reduce error accumulation and enable synchronization information exchange between any node in the network and the reference node. Moreover, we develop a fast Kalman filter (FKF) algorithm to estimate clock offset and clock skew. To reduce time complexity, we replace the calculation of gain matrices with extremely high dimension with a small matrix based on the randomization matrix approximation in the updating phase of the Kalman Filter. Simulation results show that the proposed method significantly reduces synchronization complexity without sacrificing clock synchronization accuracy, making it highly promising for future TSN deployments.

Tracing task‐based runtime systems: Feedbacks from theStarPUcase

SummaryGiven the complexity of current supercomputers and applications, being able to trace application executions to understand their behavior is not a luxury. As constraints, tracing systems have to be as little intrusive as possible in the application code and performances, and be precise enough in the collected data. In this article, we present how works the tracing system used by the task‐based runtime systemStarPU. We study the different sources of performance overhead coming from the tracing system and how to reduce these overheads. Then, we evaluate the accuracy of distributed traces with different clock synchronization techniques. Finally, we summarize our experiments and conclusions with the lessons we learned to efficiently trace applications, and the list of characteristics each tracing system should feature to be competitive. The reported experiments and implementation details comprise a feedback of integrating into a task‐based runtime system state‐of‐the‐art techniques to efficiently and precisely trace application executions. We highlight the points every application developer or end‐user should be aware of to seamlessly integrate a tracing system or just trace application executions.

Advancements in spiking neural network communication and synchronization techniques for event-driven neuromorphic systems

Neuromorphic event-driven systems emulate the computational mechanisms of the brain through the utilization of spiking neural networks (SNN). Neuromorphic systems serve two primary application domains: simulating neural information processing in neuroscience and acting as accelerators for cognitive computing in engineering applications. A distinguishing characteristic of neuromorphic systems is their asynchronous or event-driven nature, but even event-driven systems require some synchronous time management of the neuron populations to guarantee sufficient time for the proper delivery of spiking messages. In this study, we assess three distinct algorithms proposed for adding a synchronization capability to asynchronous event-driven compute systems. We run these algorithms on POETS (Partially Ordered Event-Triggered Systems), a custom-built FPGA-based hardware platform, as a neuromorphic architecture. This study presents the simulation speed of SNNs of various sizes. We explore essential aspects of event-driven neuromorphic system design that contribute to efficient computation and communication. These aspects include varying degrees of connectivity, routing methods, mapping techniques onto hardware components, and firing rates. The hardware mapping and simulation of up to eight million neurons, where each neuron is connected to up to one thousand other neurons, are presented in this work using 3072 reconfigurable processing cores, each of which has 16 hardware threads. Using the best synchronization and communication methods, our architecture design demonstrates 20-fold and 16-fold speedups over the Brian simulator and one 48-chip SpiNNaker node, respectively. We conclude with a brief comparison between our platform and existing large-scale neuromorphic systems in terms of synchronization, routing, and communication methods, to guide the development of future event-driven neuromorphic systems.

Using All-Digital On-Chip Syntonistor to Compensate Clock Frequency Error in Network Time Synchronization for Accuracy Reaching to Sub-µs Range

The emergence of Internet of Everything has made time-awareness a feature of high priority. One of the enabling factors is time synchronization. High quality synchronization demands frequency source of high stability, which is pricey and bulky. When low-end source is used, synchronization quality would be severely impaired. This situation can be improved by the technique of time synchronization. In mainstream approaches, however, the frequency of clock pulse train is not tuned due to the lack of appropriate tool. As requirement for synchronization advances into microsecond or even nanosecond regime, frequency tuning in hardware is expected to be beneficial. Moreover, wireless networks do not have frequency transfer mechanism. This exacerbates the problem of frequency deviation. Those issues make syntonization (synchronization of frequency) become necessary. In this work, an all-digital frequency-tunable clock source is used as on-chip syntonistor to physically compensate the clock frequency errors of nodes in a network. Time discrepancies are hence alleviated. A wireless network has been built to validate this scheme. Time synchronization quality has reached to sub-µs range. The key contribution is the suggestion of adopting on-chip syntonistor for improving the quality of network synchronization. This work serves as a demonstration of this new scheme.

Fractional delay Newton structure for Lagrangian interpolation in PV integrated grid connected system

SummaryThis paper proposes a fractional delay (FD) Newton structure for Lagrangian interpolation in single phase grid integrated photovoltaic (PV) system. The structure has been designed for achieving shunt compensation and as a phase locked loop circuit for synchronization. The designed controller performs multiple tasks of feeding the active power to meet the load demand and simultaneously providing reactive power compensation, power factor improvement, and compensating other power quality voltage and load current harmonics. Further, synchronization poses a severe challenge in integrating the PV power electronic converters to the grid. The FD filter is used to discretize the continuous time signal at any time instant using interpolation algorithm employing the non‐integral value of the sampling rate delays. The FD delay filter is made adaptive and self‐learning by using least mean square algorithm. The designed synchronization technique meets the objective of faithfully tracking the phase of the grid voltage under all grid disturbances such as under voltage, overvoltage, frequency variations, and phase angle disturbances in a precise manner.

Analysis of Multi-Threading and Cache Memory Latency Masking on Processor Performance Using Thread Synchronization Technique

Multithreading is a process in which a single processor executes multiple threads concurrently. This enables the processor to divide tasks into separate threads and run them simultaneously, thereby increasing the utilization of available system resources and enhancing performance. When multiple threads share an object and one or more of them modify it, unpredictable outcomes may occur. Threads that exhibit poor locality of memory reference, such as database applications, often experience delays while waiting for a response from the memory hierarchy. This observation suggests how to better manage pipeline contention. To assess the impact of memory latency on processor performance, a dual-core MT machine with four thread contexts per core is utilized. These specific benchmarks are chosen to allow the workload to include programs with both favorable and unfavorable cache locality. To eliminate the issue of wasting the wake-up signals, this work proposes an approach that involves storing all the wake-up calls. It asserts the wake-up calls to the consumer and the producer can store the wake-up call in a variable. An assigned value in working system (or kernel) storage that each process can check is a semaphore. Semaphore is a variable that reads, and update operations automatically in bit mode. It cannot be actualized in client mode since a race condition may persistently develop when two or more processors endeavor to induce to the variable at the same time.
 This study includes code to measure the time taken to execute both functions and plot the graph. It should be noted that sending multiple requests to a website simultaneously could trigger a flag, ultimately blocking access to the data. This necessitates some computation on the collected statistics. The execution time is reduced to one third when using threads compared to executing the functions sequentially. This exemplifies the power of multithreading.

Using Randomization in Self-organized Synchronization for Wireless Networks

The concept of pulse-coupled oscillators for self-organized synchronization has been applied to wireless systems. Putting theory into practice, however, faces certain obstacles, particularly in radio technologies that cannot implement pulses but use common messages for interactions between nodes. This raises the question of how to deal with interference between messages. We show that interference can disturb the synchronization process and propose low-complex, randomization-based techniques to address this issue. First, we demonstrate that randomly switching between two transmit power levels (without increasing the average power) can expedite synchronization. The high-power transmissions temporarily boost network connectivity with negligible impact on the average interference. Second, we reduce interference by blindly distributing the messages over the entire oscillator cycle. Instead of using a fixed oscillator phase at which the pulses are sent, each node chooses its own, randomly selected phase to send a synchronization message. This node-specific “fire phase” is contained in the message to permit others to compute the timing. Third, we suggest that such interference management can also be beneficial for other synchronization techniques and validate this claim using Glossy as an example. Our insights may contribute to feasible solutions for self-organized wireless synchronization. Further work is needed to gain a comprehensive understanding of the effects of randomization and to develop algorithms for the adaptability of local parameters.

A Lightweight Island Model for the Genetic Algorithm over GPGU

This paper presents a parallel approach of the genetic algorithm (GA) over the Graphical Processing Unit (GPU) to solve the Traveling Salesman Problem (TSP). Since the earlier studies did not focus on implementing the island model in a persistent way, this paper introduces an approach, named Lightweight Island Model (LIM), that aims to implement the concept of persistent threads in the island model of the genetic algorithm. For that, we present the implementation details to convert the traditional island model, which is separated into multiple kernels, into a computing paradigm based on a persistent kernel. Many synchronization techniques, including cooperative groups and implicit synchronization, are discussed to reduce the CPU-GPU interaction that existed in the traditional island model. A new parallelization strategy is presented for distributing the work among live threads during the selection and crossover steps. The GPU configurations that lead to the best possible performance are also determined. The introduced approach will be compared, in terms of speedup and solution quality, with the traditional island model (TIM) as well as with related works that concentrated on suggesting a lighter version of the master-slave model, including switching among kernels (SAK) and scheduled light kernel (SLK) approaches. The results show that the new approach can increase the speed-up to 27x over serial CPU, 4.5x over the traditional island model, and up to 1.5–2x over SAK and SLK approaches.

Cross‐border and cross‐commodity volatility spillover effects of Chinese soybean futures

AbstractThis study examines the volatility spillover between the US and China's soybean futures markets, and between China's soybean, soybean oil, and meal futures markets. A synchronization technique is used to overcome the bias from differences in the closing time of two exchanges. On the basis of BEKK‐GARCH and DCC‐GARCH on the data from January 2010 to April 2023, our results indicate that: First, there is a one‐way spillover from the US to China's No.1 soybean futures and a two‐way spillover between the US and No.2 soybean futures. Second, after 2018, the volatility spillovers of No.1 soybean futures declined, while that of No.2 increased significantly. Third, the dynamic conditional correlations confirmed our results that the spillover between No.2 soybean and soymeal, and between No.2 soybean and soyoil futures increased significantly. Our findings demonstrate the leading role of US soybeans in cross‐border trading and the increasing role of No.2 soybeans in cross‐country and cross‐commodity spillover.

Spectrofluorometric determination of orphenadrine, dimenhydrinate, and cinnarizine using direct and synchronous techniques with greenness assessment

Orphenadrine (ORP), dimenhydrinate (DMN), and cinnarizine (CNN) were investigated using green-sensitive spectrofluorometric methods. Method, I used for determination of DMN in 0.1 M hydrochloric acid (HCl) and 1.0% sodium dodecyl sulphate (SDS) at 286 nm after λex 222 nm, while for determination of ORP in 1.0% w/v SDS involves measuring the fluorescence at 285 nm after λex 220 nm. For DMN and ORP, the detection and quantitation limits were 2.99 and 4.71 and 9.08 and 14.29 ng/mL, respectively. The ranges of DMN and ORP were 0.10–1.0 and 0.04–0.5 µg/mL, respectively, in micellar aqueous solution. Method II, the derivative intensities of DMN and CNN were measured at a fixed of different wavelength between the excitation and the emission wavelengths (Δλ) = 60 nm at 282 and 322 nm, at the zero crossing of each other, respectively. The detection and quantitation limits for DMN and CNN were 1.77 and 0.88 ng/mL and 5.36 and 2.65 ng/mL, correspondingly, through the entire range of 0.1–1.0 µg/mL for DMN and CNN. The linearity was perfectly determined through the higher values of the correlation coefficient ranging from 0.9997 to 0.9999 for both direct and synchronous methods. The precision of the proposed methods was also confirmed via the lower values of the standard deviation which ranged from 0.39 to 1.11. The technique was expanded to analyze this mixture in combined tablets and laboratory-prepared mixtures. The method validation was done depending on the international conference on harmonization (ICH) recommendations. An analysis of the statistical data revealed a high agreement between the proposed data and the comparison methodology. Three different assessment methods demonstrated the greenness of the technique.

Predictive Power Control of PMSG based WECS: Development and Implementation for Smooth Grid Synchronisation, Balanced and Unbalanced Grid

In this paper, the distributed generation unit is controlled to operate in both stand-alone (SA) and grid-connected (GC) modes and offers a smooth transition between these modes using the model predictive control scheme. The permanent magnet synchronous generator (PMSG), along with a 2-level back-to-back converter, is named a DGU. A simple and intuitive approach using predictive control is presented in a stationary reference frame for a load-side converter (LSC). A voltage control loop is used during SA mode to fix the voltage and frequency at the load end. The smooth synchronization technique is developed without a phase-locked loop. During GC, a predictive power control regulates active and reactive power during the symmetry and unbalanced grid voltage conditions. The designed strategy makes the power factor improvement, reduction of grid current harmonics, and elimination of twice grid frequency ripple from power during grid unbalance possible. This work has proposed a solution to reduce the overall computational burden on the processor by eliminating the state prediction in each sampling period. The machine-end converter control is formulated in the rotor flux reference frame to keep the power flow across the dc-link capacitor constant. Comprehensive experiments are conducted with the designed scaled laboratory prototype to successfully validate the control’s theoretical claim.

FPGA realization of four chaotic interference cases in a terrestrial trajectory model and application in image transmission

This article presents a technique to integrate two dynamical models, a four-wing spherical chaotic oscillator and the elliptical path described by the planet Earth during its translation movement around the sun. Four application cases are derived from the system by varying the dynamics of the chaotic oscillator and these can be applied in information encryption to transmit RGB and grayscale images modulated by CSK. Consequently, the three main contributions of this work are (1) the emulation of the trajectories of the planet Earth with chaotic interference, (2) the CSK modulation and image encryption in a master-slave synchronization topology, and (3) the CSK demodulation for decryption without loss of information with respect to the original information. The three contributions are based on VHDL code implementation. The results of the synchronization, encryption and decryption technique were verified by means of time series and the encrypted images showed a correlation less than − 0.000142 and − 0.0003439 for RGB and grayscale format, respectively, while the retrieved image shows a complete correlation with the image original. In this work, the co-simulations were performed between MATLAB/Simulink and Vivado, using the VHDL language on two FPGA boards from different manufacturers, namely, Xilinx Artix-7 AC701 and Intel Cyclone IV.

Size-Specific Modulation of a Multienzyme Glucosome Assembly during the Cell Cycle.

Enzymes in glucose metabolism have been subjected to numerous studies, revealing the importance of their biological roles during the cell cycle. However, due to the lack of viable experimental strategies for measuring enzymatic activities particularly in living human cells, it has been challenging to address whether their enzymatic activities and thus anticipated glucose flux are directly associated with cell cycle progression. It has remained largely elusive how human cells regulate glucose metabolism at a subcellular level to meet the metabolic demands during the cell cycle. Meanwhile, we have characterized that rate-determining enzymes in glucose metabolism are spatially organized into three different sizes of multienzyme metabolic assemblies, termed glucosomes, to regulate the glucose flux between energy metabolism and building block biosynthesis. In this work, we first determined using cell synchronization and flow cytometric techniques that enhanced green fluorescent protein-tagged phosphofructokinase is adequate as an intracellular biomarker to evaluate the state of glucose metabolism during the cell cycle. We then applied fluorescence single-cell imaging strategies and discovered that the percentage of Hs578T cells showing small-sized glucosomes is drastically changed during the cell cycle, whereas the percentage of cells with medium-sized glucosomes is significantly elevated only in the G1 phase, but the percentage of cells showing large-sized glucosomes is barely or minimally altered along the cell cycle. Should we consider our previous localization-function studies that showed assembly size-dependent metabolic roles of glucosomes, this work strongly suggests that glucosome sizes are modulated during the cell cycle to regulate glucose flux between glycolysis and building block biosynthesis. Therefore, we propose the size-specific modulation of glucosomes as a behind-the-scenes mechanism that may explain functional association of glucose metabolism with the cell cycle and, thereby, their metabolic significance in human cell biology.

Clock synchronization based on pulse with propagation delay eliminated in wireless sensor networks

AbstractClock synchronization is indispensable for numerous applications of wireless sensor networks (WSNs). When no common reference clock is available, the nodes must employ distributed synchronization techniques. This paper proposes, a distributed pulse‐based clock synchronisation approach, wherein the propagation delay is eliminated through signal ping‐pongs between neighbouring nodes. Such an approach can jointly estimate the clock skew and offset without requiring any reference clock. The whole synchronization process is completed at the physical (PHY) layer, effectively avoiding the random delay caused by packet queuing and retransmission. Simulation results show that the proposed approach can achieve higher synchronization accuracy compared with other existing methods.

A novel negative feedback phase locked loop-based reference current generation technique for shunt active power filter

The use of nonlinear devices introduces current and voltage harmonics into power distribution networks. The presence of harmonics, an undesirable power quality issue, causes transformer overheating, malfunctioning of sensitive loads, power losses, and significantly reduced distribution system efficiency. Therefore, harmonics mitigation in power systems has become absolutely essential and is widely addressed, utilizing shunt active power filters (SAPFs) around the globe. The performance of SAPF in generating adequate compensating current depends on the working of three control loops used for the purpose of reference current generation, dc-link voltage control, and switching pulse generation. The existing approaches for reference current generation suffer from inherent complexity and the inability to extract positive sequence signals required for obtaining synchronizing angle during source disturbance conditions. Therefore, this paper proposes a novel negative feedback phase-locked loop-based modified synchronous reference frame technique to overcome the drawback of the existing approaches. The effectiveness of the proposed approach is investigated under ideal and non-ideal grid voltage conditions with different load perturbations. The proposed control strategy is first tested using a number of simulation-based experiments and, thereafter, validated using OPAL-RT 4510 real-time digital simulator. Compared to other existing approaches, the proposed technique has offered improved results in terms of reduced total harmonics distortion.

Modulus-based synchronous multisplitting iteration methods without auxiliary variable for solving vertical linear complementarity problems

In this work, by applying the synchronous multisplitting technique to the non-auxiliary variable modulus equation of the vertical linear complementarity problems, a new parallel method is constructed, which can generalize the existing modulus-based matrix splitting iteration method. The convergence conditions of the proposed method are discussed in the cases of more than two system matrices, and the existing results are improved. Numerical examples under OpenACC framework show that the proposed method can solve the large sparse vertical linear complementarity problems efficiently with high parallel efficiency.

The Waves and Cycles of COVID-19 Pandemic: A Phase Synchronization Approach

This study pretends to contribute to a better understanding of the COVID-19 dynamics through the non-parametric technique of phase synchronization by comparing the fifteen most affected countries by the number of positive cases plus China, where the firstoutbreak took place in December 2019. It was possible to state the number of cycles and waves for each one of the studied countries and to determine periods of synchronization between them. The results also showed the average duration of the cycles and some coincidences regarding Nason (2020); Bontempi (2021); Coccia (2021); Rusiñol, Zammit, Itarte, Forés, Martı́nez-Puchol, Girones, Borrego, Corominas, and Bofill-Mas (2021). This study is limited by the reliability of the number of positive cases reported by national governments and health authorities because of an insufficient number of tests and a great number of asymptomatic persons but presents a legit alternative to predict the evolution of the pandemic in a country due to the forward looking behavior of another one, therefore studies like this could be useful to implement contention measures and to prepare the health systems in advance.

Synchronization techniques for underwater acoustic communications

SummaryUnderwater acoustic channel is a challenging medium for communication due to the presence of significant multipath, high noise, frequency‐dependent propagation loss, and high and non‐uniform Doppler spread. Doppler shift is non‐negligible in underwater communication due to the low velocity of underwater signals. Synchronization and Doppler estimation are important requirements for achieving good performance in this channel. Synchronization algorithms that give good performance in radio communication do not work well in underwater communication. Hence, this area has received a lot of attention from researchers. This paper surveys important works in the area. The techniques proposed in the literature for frame synchronization, frequency and phase synchronization, and timing synchronization in single carrier communications are reviewed here. The synchronization techniques proposed for OFDM, MIMO OFDM, and spread spectrum communication are also surveyed. Doppler estimation methods proposed in the literature are also reviewed. It is found that most of the recent works in underwater acoustic communication focus on OFDM synchronization. Deep learning‐based methods proposed in the literature are also reviewed. Key open problems and areas that require future research attention in the field of synchronization and Doppler estimation in underwater communications are highlighted in this paper. The area needing most attention of underwater communication researchers was found to be MIMO OFDM due to the difficulty in synchronization in such systems while used in underwater communication. Reducing the computational complexity of the algorithms used is also important for future work. Schemes that work with Doppler due to relative velocity over 10 m/s also need to be developed.

Design, analysis, circuit implementation, and synchronization of a new chaotic system with application to information encryption

The practical applications of chaotic systems are gaining more dimensions every day. In this paper, a new 3D chaotic system is presented with three nonlinear terms and unique strong chaotic behavior. For the initial evaluation of the behavior of the innovative chaotic system, analyses related to equilibrium points, sensitivity, stability, Lyapunov exponent, and bifurcation have been carried out, and its strong attractor manner has been well shown. The practical realization of the designed system is shown by its circuit implementation through the use of electronic elements and Kirchhoff’s laws. To show the performance of the innovative system in practical applications, first a synchronization technique inspired by non-linear and active approaches has been designed, and then by using the innovative chaotic system in the masking technique, a new information encryption method has been derived. The results obtained from the masking based on the innovative chaotic system and the designed synchronization technique show the high functionality of the derivative encryption method.

Remote Synchronous Laceration Repair Instruction With Summary Feedback.

Social distancing and quarantine requirements imposed during the COVID-19 pandemic necessitated remote training in many learning situations that formerly focused on traditional in-person training. In this context, we developed an adaptive approach to teaching laceration repair remotely while allowing for synchronous instruction and feedback. In April 2020, 35 family medicine residents from 4 programs in the Midwest United States participated in a real-time, remotely-delivered, 2-hour virtual procedure workshop of instruction in suture techniques for laceration repair. Paired-sample t tests compared scores of learner self-confidence obtained during pre- and posttests. We interpreted short-answer responses with a mixed-methods analysis. Residents submitted photos and videos of suture techniques and received formative feedback based on a predefined rubric. All residents completed the pre- and posttests. The posttest scores for self-confidence across the participants showed significant improvement for all suture techniques. Of the 67 short-answer responses, 38 responses (56.7%) were positive; 9 (13.4%) negative; 8 (11.9%) neutral; and 12 (17.9%) a combination of positive and negative. The workshop was rated by 34 residents (97.1%) as either "about the same as prior training experiences," "better than prior training experiences," or "much better than prior training experiences." Learners reported that a remotely-delivered, real-time, synchronous suture technique workshop was a valuable experience. Further research is needed to establish the efficacy of this platform to promote procedural competence.