Synchronization Quality Research Articles

Temporal calibration and synchronization of robotic total stations for kinematic multi-sensor-systems

Abstract Despite the increasing interest in kinematic data acquisition, Robotic Total Stations (RTSs) are still relatively seldom used. No matter if Mobile Mapping Systems or Control & Guidance, GNSS is mostly used as position sensor, which limits the application to outdoor areas. For indoor applications, a combination of relative sensors is usually employed. One reason why RTSs are not used is the challenging time referencing and synchronization. In this work we analyze the challenges of a synchronized kinematic application of RTSs and present solutions. Our approach is based on a wireless network synchronization to establish a precise temporal reference frame. The achievable synchronization quality is thoroughly examined. In addition we develop a kinematic model of spherical measurements, that incorporates timing related parameters. To estimate these parameters we propose a temporal calibration utilizing an industrial robot. Both parts of our approach are evaluated using a test setup of two total stations, proofing an overall synchronization accuracy of 0.2 ms. An overall horizontal kinematic point accuracy of 2.3 mm reveals the potential of sufficiently synchronized RTSs.

Flexible multipoint-to-multipoint communication in semiconductor laser networks using one-way isolation.

We propose a type of semiconductor laser (SL) network that supports flexible chaos synchronization and multipoint-to-multipoint communications by using one-way isolation (OWI). The properties of chaos synchronization, influences of coupling strength and time delay mismatches on the quality of chaos synchronization, and the performance as well as the security of the SL network-based chaotic communications are systematically discussed. The numerical results demonstrate that, with the introduction of OWI, flexible chaos synchronization can be easily achieved in arbitrary-size SL clusters over wide parameter spaces of coupling strength and current factor. Based on the high-quality flexible chaos synchronization, satisfactory performance for Gb/s chaotic communications can be achieved in arbitrary-size clusters in the SL networks. Moreover, it is also indicated that in the SL networks, the security of intra-cluster communications can be guaranteed in three aspects. Firstly, the eavesdroppers cannot intercept any useful information by using a typical illegal attack. Secondly, due to the OWI, the chaotic carriers are only transmitted in the corresponding clusters, not transmitted among clusters, as such the security can be further improved. Thirdly, the high sensitivity of cross-correlation coefficient to the injection delay mismatches indicates that the injection delays of idle SLs to communicating SLs can be regarded as the keys of the communication clusters. The proposed scheme offers an alternative solution to flexible secure network-type communications.

ТРАНСФОРМАЦІЙНІ ПРОЦЕСИ У КАНАЛАХ КОМУНІКАЦІЇ СУЧАСНИХ РОЗДРІБНИХ ПІДПРИЄМСТВ

У статті розглянуто сучасні трансформаційні тенденції у каналах маркетингових комунікації роздрібної торгівлі зі споживачем, які лежать в основі трансформаційних процесів в організації торгівлі. Доведено, що підґрунтям для цих процесів стали підвищення диджиталізації суспільства та кожного окремого індивіда, розширення впливу Інтернет-середовища на суспільство, диференціація каналів розподілу товарів кожного окремого рітейлера та наявність певних недоліків в існуючих формах торгівлі. Окрім того, свій вплив зробили зміни у поведінці споживача: у пріоритетах стали економія часу, комфортне здійснення покупок, тяжіння до персоніфікації обслуговування та небажання спілкуватися у процесі купівлі-продажу. Усе це стало стимулом для швидкого розвитку багатоканальних та крос-канальних комунікацій та поставило перед рітейлом нові горизонти, а саме впровадження так званої безшовної комунікації з клієнтами. Основою багатоканальної та крос-канальної комунікації для офлайн-торговців стали існуючи програми лояльності. Сайт в Інтернеті, адресна розсилка каталогів та акційних пропозицій на електронну пошту, смс-повідомлення – ось перші кроки сучасної української торгівлі у напрямі багатоканальних продаж. Треба відзначити, що такий спосіб комунікації є достатньо новим для нашої країни. Він потребує значної перебудови існуючих бізнес-процесів, суттєвих витрат на впровадження CRM- та ERP-систем, нових рішень для логістичних систем. Потрібно використовувати єдиний повний каталог товарів, доповнений засобами синхронізації і забезпечення якості даних. Зрозуміло, що така перебудова потребує суттєвих витрат. Але наявні приклади впровадження омніканальної комунікації свідчать про високу ефективність трансформації, яка досягається за рахунок збільшення обсягів продаж та економії на утриманні всіх каналів збуту. Трансформаційні процеси маркетингових каналів комунікації, на нашу думку, формують нову омніканальну форму торгівлі, яка поєднуватиме в собі як магазинні, так і немагазинні форми продажу товарів, інтегруючи та поєднуючи специфічні риси обох форм.

Synchronization of coupled oscillators in presence of disturbance and heterogeneity

Disturbance and heterogeneity have a strong influence on coupled oscillator dynamics. In general, strong disturbances and heterogeneity break the robustness of the coupled system. However, the system can be protected against bounded disturbance and parameter mismatch by introducing coupling and achieving synchronization. The present work gives mathematical investigations of coupled oscillators for synchronization in the presence of bounded disturbance, which may be periodic, aperiodic, and chaotic. Also, the synchronization analysis has been carried out for second-order coupled heterogeneous oscillators. The oscillators considered are second-order Van der Pol oscillator and Fitzhugh Nagumo types of oscillators. The Lyapunov stability approach using a quadratic Lyapunov function and non-smooth Lyapunov functions have been used to obtain theoretical bound on the quality of synchronization or asymptotic synchronization depending on the type of oscillators. The numerical simulations supporting the analytical findings are reported.

Chaos synchronization and communication in global semiconductor laser network with coupling time delay signature concealment.

Chaos synchronization and pairwise bidirectional communication with coupling time delay signature (CTDS) concealment in a global heterogeneous coupled semiconductor laser (SL) network are achieved by introducing identical chaotic injections from an external SL with self-feedback. The properties of chaos synchronization and CTDSs in four indicative cases are comparatively discussed. Moreover, the influences of key parameters on the quality of chaos synchronization and the CTDS characteristics are thoroughly investigated. On the basis of the chaos synchronization, the chaotic communication performance is further analyzed. The numerical results demonstrate that with the joint contributions of heterogeneous couplings and external identical chaotic injections, isochronous chaos synchronization can be achieved between two arbitrary SLs, and simultaneously the CTDSs are suppressed to a distinguishable level close to zero, over a wide parameter range. Besides, bidirectional transmission with a bit rate beyond 6 Gbit/s can be achieved between the synchronized SLs. Comparing with the conventional two-user communication system, the proposed SL network with CTDS concealment supports flexible network-type message exchanges between pairwise SLs.

WDM-based bidirectional chaotic communication for semiconductor lasers system with time delay concealment

In this paper, we propose a wavelength-division-multiplexing (WDM)-based chaos communication configuration allowing for the bidirectional exchange of information. In the scheme, the output of a master semiconductor laser (MSL), is injected into slave semiconductor lasers (SSLs), drives the chaotic synchronization of SSLs with optical feedback and electro-optical phase feedback. By calculating the largest Lyapunov exponent (LLE), Lempel–Ziv complexity (LZC) and permutation entropy (PE), we find that the system can generate the chaotic signal with high complexity. We also demonstrate that the chaotic signal bandwidth obtained is as high as 24.68 GHz by selecting the suitable parameters; this configuration intrinsically conceals the electro-optical phase feedback time delay signature (TDS) and optical feedback TDS in transmitted variable; this delayed chaotic dynamics are identically synchronized when the parameters of emitter are exactly matched with that of receiver; while the external and internal parameters’ mismatch between emitter and receiver can lead to the decrease of the synchronization quality. In addition, the result reveals that the channel spacing has influence on cross-correlation coefficient (XCF) quantifying synchronization quality. At last, the messages introduced at two ends of the link can be successfully encrypted and decrypted, and we quantitatively analyze the corresponding Q-factor at different transmission rates.

ELM-Based Frame Synchronization in Burst-Mode Communication Systems With Nonlinear Distortion

In burst-mode communication systems, the quality of frame synchronization (FS) at receivers significantly impacts the overall system performance. To guarantee FS, an extreme learning machine (ELM)-based synchronization method is proposed to overcome the nonlinear distortion caused by nonlinear devices or blocks. In the proposed method, a preprocessing is first performed to capture the coarse features of synchronization metric (SM) by using empirical knowledge. Then, an ELM-based FS network is employed to reduce system’s nonlinear distortion and improve SMs. Experimental results indicate that, compared with existing methods, our approach could significantly reduce the error probability of FS while improve the performance in terms of robustness and generalization.

Sinusoidal Pulse Width Modulation Based Speed Control of Induction Motor using Fifteen Level Diode Clamped Multilevel Inverter

The main purpose of this work is to use a fifteen-stage diode clamped multi-level inverter that is able to control the speed of an induction motor. To get reduced synchronization and high quality sine curve output voltage. The proposed plan for the diode clamped multilevel inverter is controlled using multicarrier SPWM control. An open circle speed control can be accomplished by utilizing the V/ƒ strategy. This strategy can be executed by changing the recurrence utilized in the three-stage induction motor at the stock voltage and the consistent rate. The proposed system, which results in a poor driver performance, is a useful alternative to the conventional method with high transient losses. Simulation depicts an improved drive performance by reducing the Total Harmonic Distortion resulting from the simulation and effectively controlling the motor speed.

Synchronization in disordered superconducting arrays

This paper describes the effect of quenched disorder on the synchronization properties of a class of circuits known as Josephson junction arrays. The methodology extends the ‘dynamical systems approach’ used to analyze identical-element arrays to a ‘statistical mechanics approach’ to incorporate disorder, a topic of great importance from the perspective of device applications. The essential step is to map the circuit equations onto a version of the fabled Kuramoto model, whose tractability allows one to quantify the system-wide quality of synchronization.

A New Perspective of Using Integrated On-Chip Syntonistor for Time Synchronization in Network: Meeting the TAACCS Challenge

The emergence of Internet of Everything combined with the growing transition of telecom system from traditional wired to wireless technologies have made time-awareness a feature of high priority. One of the key elements in time-awareness applications is time synchronization, which is accomplished by synchronizing the clocks of all nodes. From TDM based network having physical connection for timing signal to connectionless packet-based network, the task of synchronizing clock becomes increasingly complex. To meet this challenge, a call for innovative design on clock circuitry used in the communicating nodes is recently put forward in TAACCS (Time-Aware Applications, Computers, and Communication Systems). In this article, an emerging frequency synthesis technique with features of small frequency granularity and fast frequency switching is suggested as on-chip integrated syntonistor for periodically tuning each nodes' clock frequency, to assist the task of time synchronization. This is a new perspective since it enables the frequency of clock hardware to be tuned continuously for better synchronization quality, not just the value of time register as traditionally done. This is a multidiscipline subject involving network architecture, VLSI circuit design and computer science.

Antiphase chaotic synchronization enhancement in a vertical cavity surface emitting laser.

In this paper, we demonstrate experimentally that a vertical cavity surface emitting laser (VCSEL) exhibits an enhancement of nonlinear polarization dynamics, i.e., antiphase chaos synchronization and mode hopping, with optical feedback (OF). The rotating orthogonal polarization of a VCSEL is used as an external parameter to generate a chaotic signal when it is reflected back with a fixed bias current and strong OF signal. The intensity of the two linear polarization modes of the VCSEL is measured for a range of bias current, which provides detailed insights into its dynamic dependence. The results show that the antiphase chaotic synchronization is enhanced as the angle of orthogonal polarization of the OF is increased. Polarization modes are oscillated entirely in the chaotic regime in antiphase synchronization, with no time delay at the bias currents of 1.2 (low) and 1.7 mA (high). However, the synchronization quality of the two modes completely deteriorates when the bias current is increased to 1.7 mA at a polarization angle of 70°, where power mode differences are increased. This result shows that the power mode difference affects antiphase synchronization dynamics and thus destroys the mode-computation effects. In addition, polarization switching takes place at the polarization angles of 60° and about 33° at low and high bias currents, respectively. Polarization mode hopping is also observed, which is associated with improvement of the antiphase synchronization dynamics.

Microtiming and Mental Effort

The present study tested two assumptions concerning the auditory processing of microtiming in musical grooves (i.e., repeating, movement-inducing rhythmic patterns): 1) Microtiming challenges the listener's internal framework of timing regularities, or meter, and demands cognitive effort. 2) Microtiming promotes a “groove” experience—a pleasant sense of wanting to move along with the music. Using professional jazz musicians and nonmusicians as participants, we hypothesized that microtiming asynchronies between bass and drums (varying from −80 to 80 ms) were related to a) an increase in “mental effort” (as indexed by pupillometry), and b) a decrease in the quality of sensorimotor synchronization (as indexed by reduced finger tapping stability). We found bass/drums-microtiming asynchronies to be positively related to pupil dilation and negatively related to tapping stability. In contrast, we found that steady timekeeping (presence of eighth note hi-hat in the grooves) decreased pupil size and increased tapping performance, though there were no conclusive differences in pupil response between musicians and nonmusicians. However, jazz musicians consistently tapped with higher stability than nonmusicians, reflecting an effect of rhythmic expertise. Except for the condition most closely resembling real music, participants preferred the on-the-grid grooves to displacements in microtiming and bass-succeeding-drums-conditions were preferred over the reverse.

PENELITIAN KONSEPTUAL: PENINGKATAN KUALITAS STRATEGIS MELALUI PENGGUNAAN TEKNOLOGI INFORMASI DAN KOMUNIKASI DALAM MENINGKATKAN KINERJA PEMERINTAH DAERAH

Kualitas perencanaan dan sinkronisasi dalam implementasi dapat dilihat dari banyaknya partisipasi masyarakat dalam proses pembangunan. Sehingga peran serta masyarakat dalam revolusi industri 4.0 ini dapat diwujudkan melalui pemanfaatan teknologi. Konsep yang ditawarkan oleh penelitian ini adalah peran Kualitas Strategis dalam meningkatkan kinerja pemerintahan daerah, yang menempatkan Teknologi Informasi dan Komunikasi (TIK) sebagai variabel moderasinya.

An Application-Level Method of Arbitrary Synchronization Failure Detection in TTEthernet Networks

Precise distributed clock synchronization is important for Time-Triggered Ethernet (TTEthernet) in which fail-arbitrary synchronization failure cannot be treated by existed protocols unless every synchronization node is equipped with a dedicated clock monitoring. A novel method was presented to detect arbitrary synchronization failure by some application-level routines which make distributed decisions mainly by monitoring the protocol control frames (PCFs). An arbitrary failure node can be exactly detected and located by the routine resided on each of the Compression Masters based on the concerned accusation messages sent from Synchronization Masters or Synchronization Clients. The proposed method can make up the weak points on the detection of the arbitrary failure node of the existed fault-tolerant synchronization mechanism and enhance the synchronization node to resist the arbitrary failure for TTEthernet. By our SAL-based model checking, this method had been formally verified to have a fail-arbitrary detection capacity even in a standard integration configuration. Simulations imply that the quality of the whole clock synchronization is effectively improved after the failure node has been isolated.

Gated 18F-FDG PET/CT of the Lung Using a Respiratory Spirometric Gating Device: A Feasibility Study.

Spirometric gating devices (SGDs) can measure the respiratory signal with high temporal resolution and accuracy. The primary objective of this study was to assess the feasibility and tolerance of a gated lung PET/CT acquisition using an SGD. The secondary objective was to compare the technical quality, accuracy, and interoperability of the SGD with that of a standard respiratory gating device, Real-Time Position Management (RPM), based on measurement of vertical thoracoabdominal displacement. Methods: A prospective phase I monocentric clinical study was performed on patients undergoing 18F-FDG PET/CT for assessment of a solitary lung nodule, staging of lung malignancy, or planning of radiotherapy. After whole-body PET/CT, a centered gated acquisition of both PET and CT was simultaneously obtained with the SGD and RPM during normal breathing. Results: Of the 46 patients who were included, 6 were prematurely excluded (1 because of hyperglycemia and 5 because of distant metastases revealed by whole-body PET/CT, leading to an unjustified extra gated acquisition). No serious adverse events were observed. Of the 40 remaining patients, the gated acquisition was prematurely stopped in 1 patient because of mask discomfort (2.5%; confidence interval [CI], 0.1%-13.2%). This event was considered patient tolerance failure. The SGD generated accurately gated PET/CT images, with more than 95% of the breathing cycle detected and high temporal resolution, in 34 of the 39 patients (87.2%; 95% CI, 60.0%-100.0%) and failed to generate a biologic tumor volume in 1 of 21 patients with increased 18F-FDG uptake (4.8%; 95% CI, 0.1%-26.5%). The quality and accuracy of respiratory signal detection and synchronization were significantly better than those obtained with RPM (P < 0.05). Conclusion: This trial supports the use of an SGD for gated lung PET/CT because of its high patient tolerance and accuracy. Although this technique seems to technically outperform RPM for gated PET/CT, further assessment of its superiority and the clinical benefit is warranted. We believe that this technique could be used as a gold standard to develop innovative approaches to eliminate respiration-induced blurring artifacts.

Cluster synchronization in mutually-coupled semiconductor laser networks with different topologies

The cluster synchronization properties of 12 different networks that consist of five semiconductor lasers (SLs) are systematically investigated through theoretical analysis and numerical simulation. The emergence of clusters in different networks is analytically predicted, and then numerically proved in SL networks. The synchronization properties between each pair of SL nodes in a network are quantified by the zero-lag cross-correlation coefficient of laser intensities. The impacts of injection strength and bias current on the synchronization quality are investigated, the robustness of clusters against noise is also considered. All the expected clusters are successfully obtained in the simulation and are robust to noise. However, for some networks, different clusters may also emerge with the variation of parameters. In addition, for most networks considered in this paper, the small difference in topologies can bring about tremendous change in synchronized clusters or the synchronization properties of clusters, but for other networks no obvious change can be observed. Moreover, the synchronization properties between nodes from different clusters are also considered. The numerical results not only validate the availability of the adopted analytical method, but also shed some light on possible applications of synchronization control or tolerance of connection failure within networks of SLs.

Features of modernization of the National network of universal time based on the experience of introducing modern time synchronization solutions in corporate networks

The article is devoted to the problems of modernization of the National network of universal time (The Service of universal time and reference frequencies) in the conditions of increasing requirements for the synchronization quality of time and frequency in sectors critical to the accuracy of time. At present, meeting the needs of different consumers in synchronization signals of the exact time is an urgent metrological task. The Resolution of the Cabinet of Ministers of Ukraine No. 664 “Issues of the Service of universal time and reference frequencies”, dated September 2, 2015, approved the Regulations on the universal time and reference frequencies, which defines the main priorities for providing Ukrainian consumers with reliable information on the exact time using the state measurement standards of the units of time and frequency.The paper presents a comparative analysis of time synchronization accuracy requirements in the main critical industry sectors.Ways of delivering accurate time signals from national time measurement standards in the context of GNSS vulnerability are considered, an examples of technical solutions for delivering accurate time signals to remote users based on current ITU-T and IEEE recommendations are provided.These technical solutions can be successfully taken into account for the development and modernization of the Service of universal time and reference frequencies. Solutions to the problem of synchronization signals delivery from national time and frequency measurement standards to users (customers) with the smallest error, based on modern equipment and taking into account the capabilities of the PTP IEEE 1588–2008 protocol as the most efficient and accurate time synchronization method, are considered. The main factors that negatively affect the accuracy of the time synchronization network constructed in accordance with the PTP 1588–2008 protocol are considered, and recommendations are given to minimize their impact while modernizing the Service of universal time.The paper presents examples of the use of various types of synchronization equipment, based on existing experience in solving such problems in modern corporate (sector) synchronization networks, such as mobile communications, energy and finance.

Effect of parameter mismatches on chaos synchronization between Josephson junctions coupled in series and driven by a central junction

Synchronization of chaos between Josephson junctions coupled in series and driven by a central junction is studied under the parameter mismatches condition. It is shown that in most cases high quality synchronization between the Josephson junctions with such a coupling topology is achievable even under significant parameter mismatches. It is also established that synchronization quality between the Josephson junctions is most sensitive to the parameter mismatches between the frequencies of the ac current driving the junctions. These results are of immense significance to obtain high power system of Josephson junctions, which can be a mobile, cost effective source of Terahertz radiation with a wide range of applications in different areas of science such as medicine, ecology, security, communication, etc.

Controlling the Synchronization of Quantum Cascade Lasers with Negative Optoelectronic Feedback by Direct Current Modulation

In this study, I presented the synchronization of quantum cascade semiconductor lasers with optoelectronic negative feedback under the effect of direct current modulation. I investigated the synchronization quality by using the rate equations model. In both open-loop system and closed-loop system, the direct current modulation in transmitter laser and receiver laser has significant effects on the correlation coefficient. In both cases, we can use the direct current modulation to minimize the effect of mismatch in delay times on the synchronization quality. Also, the effect of modulation frequency in lasers has been analyzed. The correlation coefficient has a high value with increasing the modulation frequency in both lasers. Furthermore, the present results indicate that the correlation coefficient tends to high values at the negative value of the difference in the modulation frequency between the lasers in comparison with the positive value of the difference. The correlation coefficient has different behaviors when the delay time in transmitter laser is larger than the delay time in receiver laser or vice versa.

Chaos synchronization of coupled nano-quantum cascade lasers with negative optoelectronic feedback

In this paper, a theoretical investigation of chaos synchronization in two nano-quantum cascade lasers with delayed negative optoelectronic feedback is presented. Since the spontaneous emission effect is an important factor in a microcavity the rate equations model has been reconsidered to include the Purcell spontaneous emission enhancement factor F and the spontaneous emission factor. It is found that the synchronization takes place under suitable system parameters. The results indicate that the coupling strength, the delay time in the transmitter, and the transmission time between the two lasers have significant effects on the synchronization quality while the stage number and the delay time in receiver have poor effects on the synchronization quality. Also, when the system is a closed-loop or open-loop, synchronization with poor dynamics occurs when the spontaneous emission factor is small while the synchronization happens in the open-loop system only when the spontaneous emission factor is large. Furthermore, when the system is a closed-loop, synchronization occurs when Purcell factor is large while the synchronization happens to the open-loop system of any values for the spontaneous emission factor and Purcell factor.