Sequence Components Research Articles

Advanced Microgrid Protection Utilizing Zero Sequence Components With Hard-Ware-in-the-Loop Testing

Advanced Microgrid Protection Utilizing Zero Sequence Components With Hard-Ware-in-the-Loop Testing

COLLAGE AS A WAY OF INTERTEXTUALITY (ACCORDING TO GURGEN KHANJYAN'S COLLAGES)

In the article, we have examined Gurgen Khanjyan's collages. Collage and collage thinking in general have a significant role in creating a connection between cultures, in dialogue and through this connection in discovering and understanding one's own identity. Beginning with an assessment of the narrativity of collage, this paper considers the communicative and structural poetics citing the example from Gurgen Khanjyan's works. We came to the conclusion that Gurgen Khanjyan, by intertwining the artistic text with other text insertions and collage coding, expressed the complex path of national and individual identity searches, creating a multimodal intertextual structure, where each text is the absorption and transformation of another text. By using various texts and text symbols of world and Armenian literature, Khanjyan created a new structure with interpretive findings, which comprehensively presents the picture of the path taken by the poor man since the creation of the world, as defined by the author, the persistent and constant search for salvation full of hardships, the way to get rid of suffering, which continues and will continue, is endless. Each of the collage sections of Khanjyan's works (i.e., the prose and collage-image combinations) can be read either individually or as components of a larger interconnected sequence.

ANALYSIS OF SYMMETRICAL ELECTROMAGNETIC APPARATUS FOR THREE-PHASE ZERO-WIRE NETWORKS

The most common problems of electricity quality in 0.4 kV power transmission lines are voltage deviations and voltage asymmetry, which are clearly manifested at the end sections of long lines with uneven distribution of consumers by phases. The technical means of solving these problems include devices for the uniform distribution of 1-phase consumers across the phases of a 3-phase network based on electromechanical relays, static semiconductor devices and electromagnetic devices. The purpose of the article is to analyze the operation of a symmetrical electromagnetic apparatus consisting of one three-phase winding located on a common magnetic conductor. The scientific novelty consists in determining the operating conditions of a symmetrical electromagnetic apparatus, obtaining qualitative and quantitative characteristics of its operation. The materials and methods. The object of the research is a static electromagnetic apparatus that exhibits properties of voltage and current symmetry when connected to a three-phase unbalanced electric network. The methods of theoretical electrical engineering are used, in particular, the method of symmetric components, including generally accepted methods of analyzing electromagnetic processes in electric machines, methods of mathematical and computer modeling, analysis and generalization. The accepted assumptions are: sinusoidal voltages and currents; the linearity of the magnetization curve of the magnetic core material and the absence of electrical and magnetic losses in the electromagnetic apparatus. The results of the study. It is established that the effect of equalizing currents in the line and voltage symmetry when connecting an electromagnetic device containing one three-phase winding on a common magnetic circuit occurs in the case of simultaneous fulfillment of the conditions: a) the use of a three-phase magnetic circuit in which the zero-sequence magnetic flux cannot be closed in the magnetic circuit; b) connections of transformer windings according to a scheme that allows the flow of zero-sequence currents in linear conductors. The models of the 0.4 kV line with concentrated and distributed load are considered. It is shown that with an asymmetric load, the SEA currents acquire a component of zero sequence, and the linear currents are aligned compared to the load currents. The coefficient of voltage asymmetry of the zero sequence decreases practically to zero, the reverse sequence practically does not change. The effect of voltage symmetry when connecting the SEA occurs both before and after the place of its installation. A decrease in the total losses of electrical energy in the line due to the equalization of currents is demonstrated. Conclusions. An electromagnetic device containing one three-phase winding on a common magnetic circuit has the effect of balancing the voltages and currents of a three-phase power line with a zero wire, if the design of the magnetic wire does not allow the possibility of closing the magnetic flux of zero sequence within its limits, and the winding connection circuit contains a neutral outlet connected to the zero wire of the network, through which zero-sequence currents can flow. The action of the considered electromagnetic apparatus manifests itself in equalizing the line currents in magnitude and, as a result, in reducing the total losses in it. The electromagnetic device symmetrizes the voltages before and after the place of its installation, the greatest effect is manifested when placing the proposed electromagnetic device at the end of the line or at the connection point of the most powerful consumer.

Accurate predictions of SARS-CoV-2 infectivity from comprehensive analysis

An unprecedented amount of SARS-CoV-2 data has been accumulated compared with previous infectious diseases, enabling insights into its evolutionary process and more thorough analyses. This study investigates SARS-CoV-2 features as it evolved to evaluate its infectivity. We examined viral sequences and identified the polarity of amino acids in the receptor binding motif (RBM) region. We detected an increased frequency of amino acid substitutions to lysine (K) and arginine (R) in variants of concern (VOCs). As the virus evolved to Omicron, commonly occurring mutations became fixed components of the new viral sequence. Furthermore, at specific positions of VOCs, only one type of amino acid substitution and a notable absence of mutations at D467 were detected. We found that the binding affinity of SARS-CoV-2 lineages to the ACE2 receptor was impacted by amino acid substitutions. Based on our discoveries, we developed APESS, an evaluation model evaluating infectivity from biochemical and mutational properties. In silico evaluation using real-world sequences and in vitro viral entry assays validated the accuracy of APESS and our discoveries. Using Machine Learning, we predicted mutations that had the potential to become more prominent. We created AIVE, a web-based system, accessible at https://ai-ve.org to provide infectivity measurements of mutations entered by users. Ultimately, we established a clear link between specific viral properties and increased infectivity, enhancing our understanding of SARS-CoV-2 and enabling more accurate predictions of the virus.

Semi‐Stable Active Region Around the Co‐Rotation Latitude of Low‐Mass Close Binary KIC 7671594

ABSTRACTWe present the new findings from the light variation of KIC 7671594. We have analyzed the light curve of the system, which is likely a low‐mass eclipsing close binary. We have detected a spotted active region migration on the active component. This spotted active region on the stellar surface appears to be stable during the first 2.70 years, but it exhibits rapid migration during the last 0.85 years of the observing season. The OPEA model was derived using 1128 flares and their corresponding parameters. In the model, the value was found to be 2.46703 ± 0.25234 s, and the was calculated as 7332.28 s. The flare frequency was determined to be 0.03719 , while was found to be 0.00028. We have concluded that KIC 7671594 is likely a low‐mass eclipsing binary system with a main sequence component that possesses an active region covered by some cool spots around its co‐rotation latitude.

Application of spatial metrology models in cell molecular localization and functional prediction

Understanding a protein’s exact cellular location is often essential to understanding its function. Even with the advancements in computer approaches, protein localization prediction indeed faces major obstacles such as interpretability and handling numerous localization sites. In this research, a novel approach, Squirrel Search Optimized Dynamic Visual Geometry Group Network (SSO-DVGG), is proposed to improve protein sub-cellular localization predictions by utilizing spatial metrology models to tackle these problems. With its simplified architecture, SSO-DVGG can explain whether a protein is directed to particular cellular sites, as well as identify important sequence components like sorting motifs or localization signals. This model allows users to select acceptable error levels by providing a confidence estimate for each prediction and highlighting sequence properties that are responsible for localization. This makes the model interpretable. Furthermore, SSO-DVGG uses a probabilistic methodology and integrates a large amount of data from dual-targeted proteins, which enables it to predict multiple localization locations per protein accurately. SSO-DVGG outperforms the best predictors and shows superior capacity to predict multiple localizations when tested on several independent datasets. By providing a clear and accurate understanding of protein distribution and function, this method promotes the application of spatial metrology models in cell molecular localization and functional prediction.

A low voltage ride-through approach for virtual synchronous machines under asymmetric fault conditions

Abstract With the advancement of renewable energy generation technologies, virtual synchronous machine (VSG) technology has garnered significant attention for enhancing power system stability. However, under asymmetric grid faults, the operational stability of VSMs under low voltage conditions remains a challenge. To address this, this paper presents a low-voltage ride-through strategy that utilizes dual-loop control for managing both positive and negative sequence components, aiming to improve the dynamic response of VSG during asymmetric faults. By thoroughly analyzing the VSM topology and mathematical model, an improved control scheme is developed. The effectiveness and practicality of the proposed strategy are ultimately validated through simulations under complex fault conditions.

A novel reverse and forward directional relaying scheme in six phase overhead transmission lines using adaptive neuro-fuzzy inference system

Recent power system is structurally difficult and is vulnerable to undesirable conditions like transmission faults. In this event of transmission line faults, exact fault zone detection enhances the restoration process, thus improving reliability of the complete power system. In order to solve the above problem, this paper presents an adaptive neuro-fuzzy inference system (ANFIS) based fault zone detector, which combines artificial neural network (ANN) and fuzzy logic technique (FLT) in six phase overhead transmission lines (SPOTL). To overcome the limitation of ANN and fuzzy expert system (FES) architectures and, the selection work has been formulated as an optimization method and solved using ANFIS. The inputs are the zero sequence component currents at the middle bus of the transmission line. The training data are extracted using discrete Fourier transform and collected, and then ANFIS is trained to identify the fault zone. The ANFIS based scheme reach setting has been checked for various types of faults, with a wide range of faults and transmission line parameters. Simulation study ensure that this method has a high reach setting, does not require the design of communication channel. Further, the ANFIS study shows that ANFIS is suitable for all type of faults. The ANFIS significantly outperforms other techniques proposed in the literature in terms of various evaluation metrics.

Power quality enhancement of three-phase solar photovoltaic system-based generalized integrator controlled UPQC

Abstract As distributed generation becomes increasingly prevalent, providing reliable and stable electrical energy to the grid is of paramount importance. Therefore, precise monitoring of grid voltage is necessary in order to synchronize compensating current and voltage with the grid. The Dual Second-Order Generalized Integrator (DSOGI) can extract the fundamental positive sequence component from three-phase grid signals, enabling accurate determination of grid phase and current signals for rapid and precise grid compensation. This paper presents a control algorithm for extracting and compensating UPQC reference signals based on the Second-Order Generalized Integrator (SOGI). The improved photovoltaic-fed Unified Power Quality Conditioner System (PV-UPQC) is verified and analyzed under conditions of unbalanced grid voltage, current harmonics, as well as voltage sags and swells. It can be demonstrated that the enhanced system exhibits superior adaptability to the grid.

Power Quality Enhancement in Grid-Connected Solar PV Systems Using Adaptive Control and Multilevel Inverter Topologies Under Dynamic Grid Conditions

This paper introduces a control strategy that uses an integrator-based positive sequence estimator to improve the power quality of a grid-connected double-stage solar PV system. The control extracts positive sequence components from distorted and unbalanced grid voltages to calculate unit templates and grid reference currents during grid anomalies like distortion, unbalance, sag/swell, and DC offset. A feedforward term is introduced to the photovoltaic array to ensure rapid transient response, and the DC-link voltage is adaptively regulated to reduce the voltage source converter (VSC) losses during weak grid conditions. The paper compares the performance of two-level and three-level inverters in this system configuration, highlighting the differences in power quality improvement, harmonic reduction, and system efficiency under various grid disturbances and intermittent solar conditions. Simulation results, performed in MATLAB, validate the superior performance of the three-level inverter in terms of lower total harmonic distortion (THD) in grid currents, in compliance with IEEE standard 519, while demonstrating the satisfactory response of both inverter types during challenging grid conditions like intermittent solar irradiation, DC offset, voltage distortions, unbalance, and voltage sag/swell.

Fault Section Identification for Hybrid Transmission Lines Considering the Weak-Feed Characteristics of Floating Photovoltaic Power Plant Inverters

The overhead line (OHL)–cable hybrid transmission line, which connects floating photovoltaic (PV) power plants, needs to be considered regarding whether to block reclosing operations or not. However, due to the weak-feed characteristics of PV inverters, existing methods are difficult to apply in this scenario. This paper proposes a criterion for fault section identification in the transmission lines of floating PV power plants based on traveling wave power and the zero-sequence impedance angle. Firstly, the fault current characteristics of photovoltaic inverters under dual-vector control are analyzed, and the applicability of the sequence component impedance directional criterion in this scenario is discussed. Then, the transmission, refraction, and reflection processes of traveling waves in OHL–cable hybrid lines are analyzed, and a traveling wave energy criterion is designed to determine the fault section. Finally, based on the scope of application of the zero-sequence impedance angle and traveling wave energy criterion, a fault section identification method for the hybrid lines of floating PV power plants is established. A deployment method for the proposed method, based on feeder terminal units (FTUs) at the connection points between the OHL and cable is proposed. This method identifies fault sections through traveling waves and zero-sequence impedance angles, which are unaffected by PV week feed characteristics, can be applied to all the AC fault types, and do not rely on multi-terminal synchronous sampling. The proposed method is verified on a 1MW PV system built in the PSCAD.

Research on characteristic and DC voltage balancing control of a novel three‐phase line‐voltage cascaded unity power factor rectifier under unbalanced grid

AbstractAccording to the operating modes of three‐phase line‐voltage cascaded boost high power factor rectifier topology, the operating characteristics of the rectified output voltage of each module and the characteristics of the topology for automatically balancing the input current under the unbalanced grid are analyzed in this article. Based on the analysis to the unique feature, a simple dual‐loop PI control strategy in the rotating coordinate system is designed with no need to deal with the negative sequence component of grid voltage. In response to the issue of unbalanced DC‐link capacitor voltage of each module caused by unbalanced grid, injection of the zero‐sequence voltage component is adopted in the designed control system, which make the output power of each module be able to be independently regulated, so that the balancing control to the DC‐link capacitor voltage of each module is realized. At the same time, the three‐phase input currents always remain in balance automatically operating under unity power factor. Simulations and experiments have verified the superiority of the topology structure and the feasibility of the control strategy.

Research on photovoltaic power generation prediction based on EPSO-ELM model

Abstract To increase the precision of photovoltaic power prediction (PPG), we propose a PPG algorithm based on variational mode decomposition (VMD) and enhanced particle swarm optimization (EPSO) to optimize the extreme learning machine (ELM). Firstly, VMD is employed to decompose photovoltaic power data into multiple intrinsic modal components of different frequencies, to decrease the non-stationarity of the original sequence. Secondly, an improved EPSO algorithm is constructed using Latin hypercube sampling and quadratic interpolation strategy. Then, the EPSO is used to globally optimize the ELM parameters and establish EPSO-ELM combination models for different modal sequence components. Finally, the trained combination model is used to perform multidimensional prediction on the modal feature components of each decomposed subsequence, and the modal prediction sequences of each layer are superimposed and combined to form the final output result. The simulation results prove that the constructed VMD-EPSO-ELM model has stronger robustness and higher prediction accuracy compared to conventional short-term PPG prediction models.

Excellent properties of NaF and NaBr induced DNA/gold nanoparticle conjugation system: Better stability, shorter modified time, and higher loading capacity

The functionalization of gold nanoparticle (AuNP) is the key procedure for the biochemical and biomedical application. The conventional salt-aging method requires the stepwise additions of NaCl and excessive thiolated DNA, mainly due to the poor tolerance of the DNA/AuNP mixture toward NaCl. Herein, we found that NaF is capable of improving the stability for the modification of AuNP with different bases of DNA sequences (poly A/T/C/G), and allows for adding up with a high concentration of 200 mM at one time, which greatly reduces the total modification time to 0.5–1 h. Intriguingly, the introduction of NaBr effectively increases the DNA loading capacity. Besides the advantages of NaF and NaBr, the modification performance is improved via the introduction of the oligo A/T spacer for the G-rich DNA sequences. Furthermore, this method shows the superiority to another two methods (pH 3-based and salt-aging) in terms of the loading capacity or sequence components.

Improving theories of change in conservation projects

AbstractTheory of change has become a common tool in project design because it helps teams agree on hypothesized causal pathways to a desired goal and examine their underlying assumptions. Yet, a consensus has not emerged on the specific steps and components of a theory of change. What constitutes a theory of change? Using 22 theory of change publications, we did a structured analysis of the components of a theory of change. Where there was substantial agreement among the publications on a specific component of a theory of change, we included it in the first iteration of our approach. We then ordered the components in a logical sequence, developed guidance for each component, tested them with project teams, and revised them in an iterative process. We tested and refined our guidance over 3 years with 73 teams from 18 countries. Here, we share our learning and recommendations for those interested in developing a robust theory of change for a conservation project.

Improving learning experience through implementing standardized team-based learning process in undergraduate medical education

IntroductionTeam-Based Learning (TBL) is a highly structured active learning methodology shown to have positive learning outcomes in undergraduate medical education (UME). While many medical schools have increasingly adopted TBL, there is considerable variation reported in the literature in the implementation of the standard sequence and key components of TBL. The extent to which this variation affects the benefits of TBL is not well understood. This study aims to assess the impact of implementing the standardized framework of the TBL process on student perception of the benefits of TBL.MethodsFaculty at our institute were surveyed to determine the frequency of implementation of TBL standards, as described in the literature. Second-year osteopathic medical students (OMS II) were surveyed for their perception of the experience of TBL at the beginning of the academic year. Curricular interventions targeting the enforcement of the standard steps and key components of TBL were implemented in a particular 6-week system course. The students were re-surveyed at the end of the course. Descriptive and thematic analyses were performed on quantitative and qualitative data.ResultsTwenty four of 31 (77.4%) faculty participated in the faculty survey, 53 of 105 OMS II students (50.4%) participated in the pre-intervention survey, and 72 of 104 OMS II students (69.2%) participated in the post-intervention survey. Faculty survey results indicated inconsistent implementation of key steps and components of the TBL process. Comparisons of student pre- and post-survey means of the perceived value of various aspects of TBL showed significant improvement in multiple aspects of the TBL process, including readiness assurance tests, immediate feedback, and application activities. Both before and after the intervention, students highly rated the value of teamwork and opportunities for practical application of concepts within TBL.ConclusionWhile medical students value teamwork in UME and professional development, their perception of TBL can be less than positive if not conducted deliberatively. Assessment of the implementation of the standard TBL steps and components and development of corresponding targeted interventions may improve the TBL experience of medical students. Our process could be generalized to help educators interested in improving TBL in their home institutes.

A METHOD FOR FORMING A TRUNCATED POSITIONAL CODE SYSTEM FOR TRANSFORMED VIDEO IMAGES

The article substantiates the requirements for the quality characteristics of video information services. It is shown that it is necessary to improve the quality of video information by the following indicators: time delays for video data delivery in terms of ensuring the required completeness; integrity of video information in accordance with the requirements of the application. The consequence of this fact is an imbalance between meeting the requirements for different groups of quality characteristics of video services. A set of measures is used to reduce the load on information and communication systems. One of the key ones is the use of compression technologies to reduce the bit volume. Therefore, the development of new coding technologies in terms of localising the balance between the level of video data compression and its integrity is an urgent scientific and applied problem. The article describes the main stages of creating a method for determining the informative and positional weight for a coding system in a truncated positional basis. For this purpose, a system of mathematical relations is developed to determine the number of admissible sequences. The scientific novelty is as follows. For the first time, a system of correlations has been created to determine the informative and positional weight of the components of the diagonal sequence of a transformant based on the combinatorial configurations. On the basis of experimental studies, it is shown that the developed method has advantages in terms of ensuring the level of video data integrity under conditions of a given compression rate.

Short-term power load forecasting in China: A Bi-SATCN neural network model based on VMD-SE.

This study focuses on improving short-term power load forecasting, a critical aspect of power system planning, control, and operation, especially within the context of China's "dual-carbon" policy. The integration of renewable energy under this policy has introduced complexities such as nonlinearity and instability. To enhance forecasting accuracy, the VMD-SE-BiSATCN prediction model is proposed. This model improves computational efficiency and reduces prediction errors by analyzing and reconstructing sequence component complexity using sample entropy (SE) following variational mode decomposition (VMD). Additionally, a self-attention mechanism is integrated into the temporal convolutional network (TCN) to overcome the traditional TCN's limitations in capturing long-term dependencies. The model was evaluated using data from the China Ninth Electrical Attribute Modeling Competition and validated with real-world data from a specific county in Shijiazhuang City, Hebei Province, China. Results indicate that the VMD-SE-BiSATCN model outperforms other models, achieving a mean absolute error (MAE) of 92.87, a root mean square error (RMSE) of 126.906, and a mean absolute percentage error (MAPE) of 0.81%.

Microscopic Origins of Flow Activation Energy in Biomolecular Condensates.

Material properties of biomolecular condensates dictate their form and function, influencing the diffusion of regulatory molecules and the dynamics of biochemical reactions. The increasing quality and quantity of microrheology experiments on biomolecular condensates necessitate a deeper understanding of the molecular grammar that encodes their material properties. Recent reports have identified a characteristic timescale related to network relaxation dynamics in condensates, which governs their temperature-dependent viscoelastic properties. This timescale is intimately connected to an activated process involving the dissociation of sticker regions, with the energetic barrier referred to as flow activation energy. The microscopic origin of activation energy is a complex function of sequence patterns, component stoichiometry, and external conditions. This study elucidates the microscopic origins of flow activation energy in single and multicomponent condensates composed of model peptide sequences with varying sticker and spacer motifs, with RNA as a secondary component. We dissected the effects of condensate density, RNA stoichiometry, and peptide sequence patterning using extensive sequence-resolved coarse-grained simulations. We found that flow activation energy is closely linked to the lifetime of sticker-sticker pairs under certain conditions, though the presence of multiple competing stickers further complicates this relationship. The insights gained in this study should help establish predictive multiscale models for the material properties and serve as a valuable guide for the programmable design of condensates.

Possible Identification of Precursor ELF Signals on Recent EQs That Occurred Close to the Recording Station

The Lithospheric–Atmospheric–Ionospheric Coupling (LAIC) mechanism stands as the leading model for the prediction of seismic activities. It consists of a cascade of physical processes that are initiated days before a major earthquake. The onset is marked by the discharge of ionized gases, such as radon, through subterranean fissures that develop in the lead-up to the quake. This discharge augments the ionization at the lower atmospheric layers, instigating disturbances that extend from the Earth’s surface to the lower ionosphere. A critical component of the LAIC sequence involves the distinctive perturbations of Extremely Low Electromagnetic Frequencies (ELF) within the Schumann Resonances (SR) spectrum of 2 to 50 Hz, detectable days ahead of the seismic event. Our study examines 10 earthquakes that transpired over a span of 3.5 months—averaging nearly three quakes monthly—which concurrently generated 45 discernible potential precursor seismic signals. Notably, each earthquake originated in Southern Greece, within a radius of 30 to 250 km from the observatory on Mount Parnon. Our research seeks to resolve two important issues. The first concerns the association between specific ELF signals and individual earthquakes—a question of significant importance in seismogenic regions like Greece, where earthquakes occur frequently. The second inquiry concerns the parameters that determine the detectability of an earthquake by a given station, including the requisite proximity and magnitude. Initial findings suggest that SR signals can be reliably linked to a particular earthquake if the observatory is situated within the earthquake’s preparatory zone. Conversely, outside this zone, the correlation becomes indeterminate. Additionally, we observe a differentiation in SR signals based on whether the earthquake took place over land or offshore. The latter category exhibits unique signal behaviors, potentially attributable to the water layers above the epicenter acting as a barrier to the ascending gases, thereby affecting the atmospheric–ionospheric ionization process.