Synchronization Purposes Research Articles

34 Reproductive management of beef females in tropical and sub-tropical environments

Abstract Bos indicus and Bos taurus cattle diverged from an evolutionary standpoint more than 110,000 years ago. Since then, Bos indicus cattle have undergone genetic adaptations beyond the commonly discussed increased thermo-tolerance and parasite resistance. Several physiological differences exist between Bos indicus and Bos taurus cattle, and it is important to consider these differences when establishing reproductive management strategies. It has been well described that Bos indicus cattle have a delayed onset of puberty and longer periods of postpartum anestrus, yet through the utilization of estrus synchronization protocols these challenges can be attenuated. However, when Bos indicus females are exposed to these protocols, they are known to have smaller dominant follicles, lower expression of estrus, and decreased pregnancy rates to artificial insemination (AI) when compared to Bos taurus females. These factors can be overcome through the utilization of estradiol and progesterone based synchronization protocols, which improve follicular dynamics and yield acceptable pregnancy rates to assisted reproductive technologies in cattle adapted to tropical or subtropical conditions. However, the use of estrogens for synchronization purposes is not permitted in the United States, and cattle producers need to rely on GnRH-based protocols. Another key difference between subspecies, is that Bos indicus females have greater antral follicle counts than Bos taurus females, which proves beneficial for in vitro embryo production. Therefore, an opportunity exists to explore the greater productivity of donors in embryo production in order to improve genetics in herds that utilize these breeds.

Single-Phase Frequency-Locked Loops: A Comprehensive Review

Synchronization techniques can be classified into open-loop and closed-loop methods. In power and energy applications, which are the focus here, the latter type is more popular. Phase-locked loops (PLLs) and frequency-locked loops (FLLs) are two broad categories of closed-loop synchronization techniques. The aim of this paper is providing a review of recent advances in designing single-phase FLLs, which can be very useful for both researchers and engineers. The historical development of a standard single-phase FLL, its modeling and tuning aspects, its relationship with adaptive notch filters, its advanced versions for the synchronization purposes under adverse grid conditions, its modification for different industrial applications, its connection with single-phase PLLs, and its discretization aspects are the main parts of this review.

Single-Phase FLLs Based on Linear Kalman Filter, Limit-Cycle Oscillator, and Complex Bandpass Filter: Analysis and Comparison With a Standard FLL in Grid Applications

Frequency-locked loops (FLLs) create a rather large category of closed-loop synchronization techniques, which have received considerable attention in different engineering applications, particularly for synchronization, signal processing, and control purposes. Focusing on single-phase grid applications, designing FLLs is often based on a second-order generalized integrator (SOGI), and the SOGI-FLL is regarded as a standard structure. Using the linear Kalman filter (LKF), complex bandpass filter (CBF), and circular limit-cycle oscillator (CLO) are some alternative approaches. FLLs based on these filters/elements, which are briefly referred to as the LKF-FLL, $1\phi$ -CBF-FLL, and CLO-FLL, have not been well analyzed in the literature, and limited knowledge about their real advantages/disadvantages compared to the SOGI-FLL exists. Covering this gap is the objective of this paper.

Mutually Uncorrelated Codes for DNA Storage

Mutually uncorrelated ( MU ) codes are a class of codes in which no proper prefix of one codeword is a suffix of another codeword. These codes were originally studied for synchronization purposes and recently, Yazdi et al. showed their applicability to enable random access in DNA storage. In this paper,we follow the research of Yazdi et al. and study MU codes along with their extensions to correct errors and balanced codes. We first review a well-known construction of MU codes and study the asymptotic behavior of its cardinality. This task is accomplished by studying a special class of run-length limited codes that impose the longest run of zeros to be at most some function of the codewords length. We also present an efficient algorithm for this class of constrained codes and show how to use this analysis for MU codes. Next, we extend the results on the run-length limited codes in order to study $(d_{h},d_{m})$ -MU codes that impose a minimum Hamming distance of $d_{h}$ between different codewords and $d_{m}$ between prefixes and suffixes. In particular, we show an efficient construction of these codes with nearly optimal redundancy. We also provide similar results for the edit distance and balanced MU codes. Last, we draw connections to the problems of comma-free and prefix synchronized codes.

Design and analysis of different PLLs as load compensation techniques in 1-∅ grid-tied PV system

ABSTRACTThis paper discusses the design, modelling and analysis of a single-phase grid-tied photovoltaic (PV) system feeding a variety of loads. Normally, the phase-locked loop (PLL) circuits are used for synchronisation purposes and generation of in-phase and quadrature templates. However, this paper presents an interesting application of PLLs for achieving load compensation for power quality improvement as well as estimation of phase and frequency. Three PLL algorithms are considered which include the conventional Delay PLL, Enhanced PLL and Second-Order Generalised Integrator Frequency-Locked Loop (SOGI-FLL). Design and modelling of controllers using these PLLs for achieving power quality improvement is also presented in the paper. Suitable comparisons are drawn to investigate the performance of different PLLs for two purposes viz. grid synchronisation and achieving compensation in a single-phase grid-tied PV system. Finally, the application of SOGI-FLL for control of a 5 kW PV interfaced single-phase compensator for power quality improvement is presented. Appropriate experimental results are shown along with simulation results for suitable comparison.

Intelligent E-commerce logistics platform using hybrid agent based approach

This paper proposes a hybrid agent-based approach for the scheduling and synchronization of e-commerce logistics parks (EcLP). This is accomplished by integrating intelligent distribution centers within the e-commerce environment. The proposed platform has been developed based on an agent technology, which not only serves for decentralization and synchronization purposes but also it has been optimized for the transportation and logistics of the overall system. Moreover, mobile agent-based communication mechanisms between the hardware agents and the software agents were developed, and the proposed hybrid agent-based platform was implemented and tested based on a case study. Following this, the results were compared to a conventional system based on four main indicators.

Voice-over Translation of News Programs on Television: Evidence from Iran

Compared with dubbing and subtitling research, the current literature on voice-over translation is fairly scare, and research has been mainly reported from Europe. Likewise, there are few reports on the topic from an Asian context including Iran. The main goal of this paper is, therefore, to examine voice-over translation in Iranian news broadcasting. The study uses a corpus of English news materials translated into Persian and have been broadcast on Iranian Television. The study has described Persian translation for voice-over from two perspectives: synchronization techniques, and faithfulness and ideology in translation. The overall findings suggest that voice-over translation is a common modality used for translation of foreign news reports in Iran, which entails considerable appropriation and manipulation due to solutions adopted for synchronization and ideological purposes of the news agency.

Modeling, Tuning, and Performance Comparison of Second-Order-Generalized-Integrator-Based FLLs

The second-order-generalized-integrator-based freq-uency-locked loop (SOGI-FLL) is a well-known tool for filtering and synchronization purposes in the power and energy applications. The SOGI-FLL, nevertheless, has a limited ability in rejecting the grid voltage disturbances. To deal with this problem, two advanced SOGI-FLLs have been proposed recently. In the first one, a SOGI-based filter is included inside the standard SOGI-FLL control loop, and in the second one, a SOGI-based filter is employed as the prefiltering stage of the SOGI-FLL. The small-signal modeling, tuning procedure, and detailed performance comparison of these advanced SOGI-FLLs have not been carried out yet. The aim of this paper is to cover these issues.

Steady-State Linear Kalman Filter-Based PLLs for Power Applications: A Second Look

In three-phase power and energy applications, the synchronous reference frame phase-locked loop (SRF-PLL) is a popular tool for synchronization purposes. The SRF-PLL can be easily and effectively customized for different scenarios by changing its loop filter. Recently, some supposedly different PLLs using the steady-state linear Kalman filter have been developed. The main aim of this letter is to analyze these PLLs. It is demonstrated that they are actually equivalent to some well-known SRF-PLL structures and, therefore, provide no advantage compared to them.

Design and performance analysis of generalised integrator-based controller for grid connected PV system

ABSTRACTThis article discusses the design and control of a single-phase grid-connected photovoltaic (PV) system. A 5-kW PV system is designed and integrated at the DC link of an H-bridge voltage source converter (VSC). The control of the VSC and switching logic is modelled using a generalised integrator (GI). The use of GI or its variants such as second-order GI have recently evolved for synchronisation and are being used as phase locked loop (PLL) circuits for grid integration. Design of PLL circuits and the use of transformations such as Park’s and Clarke’s are much easier in three-phase systems. But obtaining in-phase and quadrature components becomes an important and challenging issue in single-phase systems. This article addresses this issue and discusses an altogether different application of GI for the design of compensator based on the extraction of in-phase and quadrature components. GI is frequently used as a PLL; however, in this article, it is not used for synchronisation purposes. A new controller has been designed for a single-phase grid-connected PV system working as a single-phase active compensator. Extensive simulation results are shown for the working of integrated PV system under different atmospheric and operating conditions during daytime as well as night conditions. Experimental results showing the proposed control approach are presented and discussed for the hardware set-up developed in the laboratory.

Exploitation of Mobile Edge Computing in 5G Distributed Mission-Critical Push-to-Talk Service Deployment

There is a growing interest in adapting mission critical public-safety communications from traditional private radio technologies toward 5G. The need for resiliency and strong delay requirements has resulted in mobile edge computing (MEC) emerging as a key technology to improve the deployment of public safety applications over the mobile network. This paper presents a non-standalone 5G ETSI MEC-based architecture for mission-critical push-to-talk (MCPTT) services. The proposal suggests a hierarchical distributed MCPTT architecture that allocates the user plane at the edge, keeping the control plane (CP) centralized for synchronization and assistance purposes. The MEC architecture enables the deployment of low latency services, due to the proximity of functional servers to the end-user, releases user equipment from heavy workloads, and benefits from horizontal scalability to provide dynamic allocation of network resources at specific locations. The proposed architecture is also beneficial in an isolated E-UTRAN operation situation, where in the case of backhaul connection loss, local MCPTT services can be straightforwardly deployed within an isolated group of eNodeBs.

Unique-Word GFDM Transmission Systems

In this letter, we propose the use of a deterministic sequence, known as unique word (UW), instead of the cyclic prefix in generalized frequency division multiplexing (GFDM) systems. The UW consists of known sequences that, if not null, can be used advantageously for synchronization and channel estimation purposes. In addition, UW allows the application of a highly efficient linear minimum mean squared error (LMMSE) smoother for noise reduction at the receiver. To avoid the conditions of non-orthogonality caused by the insertion of the UW and performance degradation in time varying frequency-selective channels, we use frequency-shift offset quadrature amplitude modulation. We present a signal model of a UW-GFDM system considering a single and multiple UWs. We then develop an LMMSE receive filter for signal reception of the proposed UW-GFDM system. Simulations show that the proposed UW-GFDM system outperforms prior work.

Reactive-Power Coordination in VSC-HVDC Multi-Terminal Systems for Transient Stability Improvement

This paper proposes a new control strategy for the reactive-power injections of voltage-source converters (VSCs) in high-voltage direct-current multi-terminal systems to improve power system transient stability. A reactive-power supplementary signal is provided for each converter. Its value is proportional to the frequency deviation of its corresponding AC bus with respect to the weighed-average frequency of the multi-terminal system stations. The purpose is to increase (decrease) the electromagnetic torque of generators close to those terminals, in which the frequency is above (below) the weighed-average frequency used. The AC frequency for all VSC stations is always available locally for synchronization purposes and could be used by a central controller. Simulations have been carried out using PSS/E, and the results have shown that transient stability can be improved using this strategy. Since this approach uses global measurements of all VSC stations, the impact of the communication delays has been analyzed, concluding that the negative effect is small, for realistic latency values.

Elaboration of a generalized approach to control and to synchronize the fractional-order chaotic systems

In this paper, a new general optimal structure and parameters of the fractional-order feedback control law (OSP-FoF) is developed for controlling and synchronizing a large class of fractional-order chaotic systems (FoCS). The design of the OSP-FoF model is based on bounded-input bounded-output stabilization arguments, small gain theorem (SGT), and the matrix norms. The proposed model is theoretically rigorous and represents a powerful and simple approach which provides a reasonable trade-off between computational overhead, storage space, numerical accuracy and stability analysis for control and synchronization purposes of FoCS. Simulation results for the stabilization and synchronization of fractional-order hyperchaotic systems demonstrate the effectiveness of this newly proposed approach.

An Adaptive Quadrature Signal Generation-Based Single-Phase Phase-Locked Loop for Grid-Connected Applications

The quadrature signal generation-based phase-locked loops (QSG-PLLs) are highly popular for synchronization purposes in single-phase systems. The main difference among these PLLs often lies in the technique they use for creating the fictitious quadrature signal. One of the most popular QSG approaches is delaying the original single-phase signal by a quarter of a cycle. The PLL with such QSG technique is often called the transfer delay-based PLL (TD-PLL). The TD-PLL benefits from a simple structure, rather fast dynamic response, and a good detection accuracy when the grid frequency is at its nominal value, but it suffers from a phase offset error and double-frequency oscillatory error in the estimated quantities in the presence of frequency drifts. In this paper, a simple yet effective approach to remove the aforementioned errors of the TD-PLL is proposed. The resultant PLL structure is called the adaptive TD-PLL (ATD-PLL). The stability of the ATD-PLL is evaluated by the derivation of its small-signal model. Parameter design guidelines are also presented. Finally, the effectiveness of the ATD-PLL is confirmed using numerical results.

An Adaptive Least-Error Squares Filter-Based Phase-Locked Loop for Synchronization and Signal Decomposition Purposes

Without any doubt, phase-locked loops (PLLs) are the most popular and widely used technique for the synchronization purposes in the power and energy areas. They are also popular for the selective extraction of fundamental and harmonic/disturbance components of the grid voltage and current. Like most of the control algorithms, designing PLLs involves a tradeoff between the accuracy and dynamic response, and improving this tradeoff is what recent research efforts have focused on. These efforts are often based on designing advanced filters and using them as a preprocessing tool before the PLL input. A filtering technique that has received a little attention for this purpose is the least-error squares (LES)-based filter. In this paper, an adaptive LES filter-based PLL, briefly called the LES-PLL, for the synchronization and signal decomposition purposes is presented. The proposed LES filter can be understood as an adaptive complex-coefficient filter because its implementation involves cross couplings between orthogonal axes. The stability of designed LES-PLL is analyzed by the derivation of its small-signal model. Some control design guidelines are also presented. The effectiveness of proposed PLL structure is finally evaluated using experimental results.

Improved semi‐blind spectrum sensing for cognitive radio with locally optimum detection

In cognitive radio, there might be some information about primary users’ signals available at secondary users’ receivers since communications systems usually employ training signals for channel estimation and synchronization purposes. This training information can be exploited along with data symbols to perform semi-blind detection of primary users’ signals. In the literature, it is considered that the locally optimal semi-blind detection metric is the linear combination of the energy detector (ED) and the matched filter, i.e. the hybrid detector. Locally optimum detection (LOD), known to be optimum in the low signal-to-noise ratio, is proposed here in the design of a weighted semi-blind locally optimum detector (WSBLOD) by focusing on linear modulation in presence of an unknown phase shift and additive white Gaussian noise. By using LOD, it is shown that for binary phase shift keying-modulated signals, the semi-blind detector test statistic consists not only in combining linearly the matched filter and the ED but also the pseudo-energy of the received signal. Then, the designed semi-blind detector is improved by optimising the weights of the matched filter, energy and pseudo-energy in the test statistic, which maximises the probability of detection. Simulation results show that the proposed WSBLOD outperforms the hybrid detector.

Low‐complexity method for primary synchronisation in the third generation partnership project long term evolution downlink system

In this study, the authors propose a low-complexity method for symbol synchronisation in the third generation partnership project long term evolution (LTE) downlink system. The authors introduce the lowest sampling frequency of a receiver for synchronisation purposes. Using a low sampling frequency at the receiver means that the digital signal is decimated and a lower number of processing samples is needed. This results in reducing the computational complexity. It is also shown that this advantage comes at the cost of signal-to-noise ratio degradation and insertion of a systematic error in synchronisation that can be avoided by choosing a proper decimation factor. A thorough analysis is also conducted for all possible sampling frequencies that reduce the computational complexity of LTE cell search. To show the validity of the authors’ method, they implemented an LTE primary synchroniser in C++ using GNU Radio libraries and prepared a software-based radio modem, tested in different conditions. Some Monte-Carlo simulations are carried out to compare the proposed method with other low-complexity methods. These comparisons show the suggested method is faster than available techniques in literatures.

Modernizing the Global Approximation Method of Posterior Probability Density for Oscillator Synchronization Purposes

Modernizing the Global Approximation Method of Posterior Probability Density for Oscillator Synchronization Purposes

Five channel WDM communication using a single a:SiC-H double pin photo device

Amorphous SiC heterostructures built as a double pin device has a non linear spectral gain which is a function of the signal wavelength that impinges on its front or back surface. Illuminating the device with several single wavelength data channels in the visible spectrum allows for Wavelength Division Multiplexing (WDM) digital communication. Using fixed ultra-violet illumination at the front or back surfaces enables the recovery of the multiplexed channels. Five channels, each using a single wavelength which is modulated by a Manchester coded signal at 12,000bps, form a frame with 1024 bits with a preamble for signal intensity and synchronisation purposes. Results show that the clustering of the received signal enables the successful recovery of the five channel data using the front and back illumination of the surfaces of the double pin photo device.