Virtual Reference Research Articles

Digital Reference Service: A Tool to Expand Horizons of Library Services

Digital Reference Service: A Tool to Expand Horizons of Library Services

Adaptive Supplementary Control of VSG Based on Virtual Impedance for Current Limiting in Grid-Connected and Islanded Microgrids

By applying virtual synchronous generator (VSG) method in high penetration level microgrids, current limiting issue under fault condition has become an important challenge. The main objective of this paper is to propose a novel current limiting strategy which has the capability of voltage tracking error reduction to avoid voltage controller saturation. This purpose is obtained by adaptive virtual impedance-based reference voltage correction during fault condition. Furthermore, positive and negative peak detection-based current limiting method implemented in double loop control system prepares soft transition ability. Moreover, this current limiting method generates the adaptive term of virtual impedance part. In contrast to conventional VSG methods, the proposed approach provides high quality voltage and current for microgrid in both grid-connected and islanded modes during fault conditions. The offline and hardware in the loop (HIL) simulation results confirm that the peak current of the inverter is restricted to the threshold value under symmetrical and asymmetrical faults for two operating modes of microgrid.

DIGITAL LINGUISTIC AND CROSS-CULTURAL REFERENCE GUIDE AS A MEANS OF SOCIO-CULTURAL COMPETENCE FORMATION IN TEACHING RUSSIAN AS A FOREIGN LANGUAGE

The article is devoted to the issues of improving the linguodidactic arsenal of means for developing the sociocultural competence of foreign students from Arabicspeaking countries, expanding the teacher's methodological tools, increasing the degree of implementation of the principle of multimodality, optimizing the learning process of RFL and organizing independent work of students. The purpose of this article is to methodologically substantiate a new linguodidactic means of developing sociocultural competence when teaching Russian as a foreign language to an Arabic-speaking audience at the initial stage - a digital linguistic and cultural reference book. The first part of the article provides a theoretical overview of current research devoted to the search for ways to present educational material of a reference nature in the form of a linguistic and cultural dictionary, a linguistic and cultural commentary, including through digital tools, their effective and appropriate inclusion in the teaching of RFL at different stages in order to build up background knowledge and formation of sociocultural competence, which emphasizes the relevance and timeliness of the development and creation of a digital linguistic and cultural directory...

Robust cascade controller design for discrete minimum phase system using a novel data-driven virtual reference feedback tuning approach

Robust cascade controller design for discrete minimum phase system using a novel data-driven virtual reference feedback tuning approach

Robust cascade controller design for discrete minimum phase system using a novel data-driven virtual reference feedback tuning approach

Robust cascade controller design for discrete minimum phase system using a novel data-driven virtual reference feedback tuning approach

Artificial Intelligence and Deep Learning-based Model for Indoor Environment: with Virtual Reference Tag Allocation

By the evolution of context-aware application, indoor location positioning gains much more attention worldwide. Radio Frequency Identification (RFID) is one such wireless positioning technology adopted widely. Moreover, enhancing the tracking accuracy and thus reducing the tracking error remains a challenging task in RFID based indoor environment. So as to overcome this aspect, a localization and tracking method depending on virtual reference tag (VRT) is employed in the indoor environment. This research work includes four modules like (i) data collection and Received Signal Strength Indication (RSSI) estimation;(ii) Optimal allocation of VRT using Spider Monkey Optimization (SMO) at which the allocation of VRT is made by considering number of tags, environmental factors (humidity and temperature), and SNR. Based on this data, the RFID reader allocates VRT for each grid so as to increase the tracking accuracy; (iii) Artificial Neural Network (ANN) module-based localization at which the localization of unknown tags is made; and (iv) tracking of moving target tag is carried based on Aquila Swarm Optimization-Long short-term memory (ASO-LSTM) approach. The optimization at this stage is employed to choose optimal position which enhances the accuracy of tracking. Thus, finally the location estimation is carried by this approach. The simulation is carried in NS3.26 network simulator and the performance are estimated in terms of SNR, tracking error, mean error, tracking accuracy, mean time, and standard deviation. The performance value is then compared with traditional models to show the enhancement of proposed mode over the other conventional techniques.

A Virtual Reference Point Kinematic Guidance Law for 3-D Path-Following of Autonomous Underwater Vehicles

A Virtual Reference Point Kinematic Guidance Law for 3-D Path-Following of Autonomous Underwater Vehicles

Fractional-order VRFT Reference Model and Controller Synthesis for Uniformity Temperature Control Applications

Data-driven controller synthesis methods allow finding controller parameters based only on the system input-output response. Among these methods, Virtual Reference Feedback Tuning (VRFT) is accepted thanks to its reference-model based direct parameters synthesis, including robustness and noise rejection considerations for integer and fractional-order controller design. However, for fractional-order VRFT controller synthesis, a direct solution is harder to reach involving a complex optimization problem to solve. This paper presents a recursive VRFT method for synthesizing arbitrary degree fractional-order controllers with feedforward based on a integer or fractional-order reference model. This methodology leverages existing optimization tools for fractional-order systems identification to obtain integer and fractional-order controller gains when integer and fractional-order reference models are used for the virtual error computation. The proposed method synthesizes a set of feedforward VRFT controllers implemented to control a uniform temperature control system. The results show that combining a fractional-order model or compensator improves the energy consumption of the controller and the transient temperature response in tracking and regulation tasks.

Data-Driven Control Approach for Scalability Enhancements in Reconfigurable Manufacturing Systems

Scalability is crucial for reconfigurable manufacturing systems (RMS), allowing throughput capacity adjustments based on market demand shifts. This research applies control theory to assess scalability’s impact on RMS, understanding dynamic responses to production demand variations. Strategies are explored to efficiently manage changes, maximizing manufacturing process effectiveness. Using a discrete transfer function, the study employs virtual reference feedback tuning (VRFT) with a proportional-integral-derivative (PID) control strategy. This sophisticated, data-driven approach analyzes system responses, identifying opportunities for optimization. Integrating VRFT-PID offers a nuanced perspective, enhancing understanding of RMS behavior and refining control strategies to optimize throughput capacity in response to market dynamics.

Attitude Estimation From Vector Measurements: Necessary and Sufficient Conditions and Convergent Observer Design

The paper addresses the problem of attitude estimation for rigid bodies using (possibly time-varying) vector measurements, for which we provide a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">necessary and sufficient</i> condition of distinguishability. Such a condition is shown to be strictly weaker than those previously used for attitude observer design. Thereafter, we show that even for the single vector case the resulting condition is sufficient to design almost globally convergent attitude observers, and two explicit designs are obtained. To overcome the weak excitation issue, the first design employs to make full use of historical information, whereas the second scheme dynamically generates a virtual reference vector, which remains non-collinear to the given vector measurement. Simulation results illustrate the accurate estimation despite noisy measurements.

ВОПРОСЫ ХРАНЕНИЯ И КОМПЛЕКТОВАНИЯ ЭЛЕКТРОННЫМИ ДОКУМЕНТАМИ ГОСУДАРСТВЕННЫХ АРХИВОВ НА СТРАНИЦАХ АРХИВОВЕДЧЕСКИХ ЖУРНАЛОВ, ОПУБЛИКОВАННЫХ В 2011-2020 ГГ. ("ОТЕЧЕСТВЕННЫЕ АРХИВЫ" И "ВЕСТНИК АРХИВИСТА")

The article reviews the main publications of 2011–2020, published in the journals “Otechestvennye arkhivy” and “Herald of an Archivist”, concerning the issues of keeping electronic archival documents, their entry into state safekeeping, as well as the experience of the archival institutions practical work in the field of digital records. Based on the historiographical material, the main directions discussed in the professional community on the pages of those journals are identified. In the period from 2011 to 2014, the issues of creating a digital fund for the use of archival documents and digitization of archival records in general were actively discussed. Theoretical aspects of digital records management were studied by the authors on the pages of periodicals in 2014-2015. In the period from 2016 to 2020, the key topics of the theory of digital records were the issues of creating a digital reference apparatus, as well as those of ensuring the digital records keeping. The analysis of the articles made it possible to draw conclusions about the regular advance of archival thought in the direction of theoretical and practical development of the problems of acquisition and preservation of digital records, and also to correlate the frequency of publications in those journals with the publication of key normative and methodological documents in the f ield of archives and records management.

Examine the Challenges and Barriers Hindering Distance Learners' Access to Academic Library Resources

This research evaluates the barriers and challenges towards distance learners' access to academic libraries' physical and digital resources, databases, catalogs, and technological infrastructure, as well as the accessibility of virtual reference services and online tutorials. This research provides practical measures to improve library conditions, assist administrators in formulating effective policies, and benefit library professionals. The study aims to fill the gap in the Library and Information Science literature and contribute to knowledge in the field. A questionnaire was used for a nature of survey, and data was collected from six distance education providing universities in Pakistan selected from the Higher Education Commission HEC- Pakistan website. Two universities discontinued their programs, so data was collected from the remaining four. A sample of 200 students was selected, and 178 responses were received. Two incomplete responses were discarded, and the 176 responses were analyzed using SPSS. Distance education has become more available around the globe, and the number of distance learning students increases day by day. In response to the growing popularity of distance education, libraries and librarians identify their needs and then provide the best available services to these off-campus part-time students.

A novel saturated PID‐type observer‐based controller for wheeled mobile robots with a guaranteed performance considering path curvature

AbstractThis article proposes a novel saturated PID‐type formation controller for a class of nonholonomic wheeled mobile robots (WMRs) of type (m, s) with mobility m and steerability s. Since the path curvature causes a severe deviation of the followers from the leaders' trajectory in the corners, a new definition of output equations is suggested to construct the coordinates of a virtual reference point in the front of each follower based on the concept of the extended look‐ahead control that utilizes a corrective angle to compensate the trajectory curvature efficiently. A nonlinear transformation and the robot's kinematic and dynamic equations are heuristically combined to develop a novel second‐order Euler–Lagrange formulation of unconstrained errors from constrained errors. Then, a novel saturated PID‐type controller is proposed for WMRs to build a desirable formation with a prescribed performance. An innovative nonlinear observer is presented to estimate followers' velocities. An efficient mixture of a radial basis function neural network (RBFNN) and an adaptive mechanism is proposed to compensate for model uncertainties, external disturbances, and network approximation errors. Lyapunov's direct method verifies semi‐global uniform ultimate boundedness stability by estimating a gain‐dependent region of attraction. Numerical simulations finally show the efficiency of the proposed controller.

Detectability and accuracy of computational measurements of in-silico and physical representations of enlarged perivascular spaces from magnetic resonance images

BackgroundMagnetic Resonance Imaging (MRI) visible perivascular spaces (PVS) have been associated with age, decline in cognitive abilities, interrupted sleep, and markers of small vessel disease. But the limits of validity of their quantification have not been established. New methodWe use a purpose-built digital reference object to construct an in-silico phantom for addressing this need, and validate it using a physical phantom. We use cylinders of different sizes as models for PVS. We also evaluate the influence of ‘PVS’ orientation, and different sets of parameters of the two vesselness filters that have been used for enhancing tubular structures, namely Frangi and RORPO filters, in the measurements’ accuracy. ResultsPVS measurements in MRI are only a proxy of their true dimensions, as the boundaries of their representation are consistently overestimated. The success in the use of the Frangi filter relies on a careful tuning of several parameters. Alpha= 0.5, beta= 0.5 and c= 500 yielded the best results. RORPO does not have these requirements and allows detecting smaller cylinders in their entirety more consistently in the absence of noise and confounding artefacts. The Frangi filter seems to be best suited for voxel sizes equal or larger than 0.4 mm-isotropic and cylinders larger than 1 mm diameter and 2 mm length. ‘PVS’ orientation did not affect measurements in data with isotropic voxels. Comparison with existent methodsDoes not apply. ConclusionsThe in-silico and physical phantoms presented are useful for establishing the validity of quantification methods of tubular small structures.

Developing Students’ Scientific Literacy through Wikipedia Digital Library

This study investigates the impact of utilizing the digital library Wikipedia on high school students’ scientific literacy skills in biology. This research used a quasi-experiment design with a one-group pre-test and post-test method, conducted in a high school in Bandung, Indonesia. The participants consisted of 60 tenth-grade students. The research instrument consisted of 24 multiple-choice questions designed to assess nine scientific literacy indicators, including the ability to describe phenomena scientifically, design and evaluate scientific investigations, and interpret data and evidence scientifically. Each question was scored dichotomously, with the correct answer receiving a score of 1 and incorrect answers assigned a score of 0. Pre-test and post-test scores were analyzed using the Rasch model through Winsteps Version 3.73. Based on data analysis, the items fit with the Rasch model because the infit and outfit MNSQ is 1.0 and the residual item of unexplained variance is 2.3% to 9.8%. The reliability of the items shows an item value of 0.97, which is classified as excellent. The indicators considered the most difficult before being treated were identifying accurate scientific ideas, distinguishing between types of sources, and evaluating literature source validity after the treatment. There was a significant improvement in students’ scientific literacy skills after utilizing the digital library, Wikipedia. The findings provide valuable insights into the effectiveness of integrating digital media into biology courses, highlighting the potential of Wikipedia as a digital reference source for enhancing students’ scientific literacy in high school settings.

The Accuracy of Full-Arch Intraoral Optical Impressions (IOS): Clinical Pilot Study of the Influence of the Scan Strategy, Operator, and Intraoral Scanner.

To investigate the influence of a novel scanning strategy-using two new intraoral scanner devices with different operators-on the full-arch scanning accuracy for a dentate maxilla. Two scanning strategies, a test and a control strategy, were used to produce full-arch impressions of the dentate maxilla of a study patient. Two intraoral scanning (IOS) devices were used. Five expert operators performed a total of 40 scans. The scan time was recorded for each. A reference model was obtained from the patient's maxillary arch with an analog impression. The model was later scanned with a high-precision laboratory scanner to create a digital reference model (DRM). The scanning accuracy was analyzed with 3D-analysis software using a root mean square (RMS) calculation method, and qualitative analysis was executed using machine learning software. The mean RMS result for the test strategy was 82.8 ± 16 μm compared to 81.5 ± 16 μm for the control strategy. The mean RMS results were 84.7 ± 15 μm for Primescan (PS) and 79.6 ± 17 μm for 3Shape (3S). As such, the scanning strategies and IOS devices did not influence the scanning accuracy. Yet, a significant difference was found when the two strategies' scanning times were compared (P = .001), as well as the IOS devices (P = .001). The operator was found to have no influence on the scanning strategy. The accuracy of digital impressions is not influenced by different strategies, devices, or operators, in contrast with the scanning time, which is influenced by both strategies and devices.

Differences Between the Perception and Use of Virtual Reference Services for Complex Questions

Differences Between the Perception and Use of Virtual Reference Services for Complex Questions

Hong Kong Students Consider Virtual Reference a Vital Service and It Can Aid in Many Stages of Learning

A Review of: Tsang, A. L. Y., &amp; Chiu, D. K. W. (2022). Effectiveness of virtual reference services in academic libraries: A qualitative study based on the 5E learning model. The Journal of Academic Librarianship, 48(4), Article 102533. https://doi.org/10.1016/j.acalib.2022.102533 Objective – Understand how virtual reference services (VRS) impact students’ learning using the 5E model (engage, explore, explain, elaborate, evaluate) as a theoretical framework. Design – Exploratory qualitative study. Setting – Major university in Hong Kong. Subjects – There were 10 participants between the ages of 18 and 35, including undergraduate and postgraduate students and one alumnus of the university. Methods – Online synchronous semi-structured interviews of 30 minutes via Zoom. Interview data were transcribed and analyzed thematically according to the 5E learning model. Main Results – WhatsApp was the preferred form of VRS, over Zoom, email, or phone. VRS can facilitate better awareness of library resources and supports resource exploration. WhatsApp VRS is particularly valuable for students who may find other modes intimidating, overly formal, or inaccessible due to time constraints. VRS has grown in importance since the COVID-19 pandemic. Conclusion – VRS provided via instant messaging is a valued service for students, but libraries, library websites, and librarians can all work to improve awareness of the option and possible uses. Future work is needed to understand how demographics may influence patrons’ attitudes and experiences of VRS.

Techno-Sociopreneur In Improving Competitiveness of Agricultural Commodities

This paper contributes to providing an understanding of the dynamics of Techno-sociopreneur in increasing the competitiveness of agricultural commodities. First, this paper will explain the concept of Techno-sociopreneur in agricultural development from the beginning of the concept used in a scientific context. Then it will also be explained what are the components forming Techno-sociopreneur development in increasing the competitiveness of agricultural commodities, and what variables will be the novelty of research in Techno-sociopreneur research in increasing the competitiveness of agricultural commodities. The research method used is a qualitative approach with a literature review system from various best journal sources on Google Scholar, Garba Digital Reference (Garuda), Scinence direct and other relevant sources. The conclusion of this article is to explain the development of the concept of Techno-sociopreneur agricultural development can be categorized into scientific concepts of study, namely a) Innovation, b) Support of Stake Holders, c) Social, Cultural and Economic environment, and d) Empowerment. Research questions for the future related to Techno-sociopreneur based on local economic institutions in increasing the competitiveness of agricultural commodities which point to the context of the impact of Techno-sociopreneur in agricultural development, the role of Techno-sociopreneur based on local economic institutions in increasing the competitiveness of agricultural commodities and Techno-sociopreneur factor based on local economic institutions in increasing commodity competitiveness horticultural agriculture. Because studies on this have not been carried out by previous researchers both in developed countries and in developing countries.

Is there a place for a (Virtual) European Network and reference centers on Pelvic Venous Disease (PeVD)? Thinktank?

The creation of a virtual European network and reference centers, targeted at Pelvic venous disease, holds promising potential for the medical and research communities. Nevertheless, effective implementation of the initiative necessitates prudent planning, funding, and support. The establishment of such networks and reference centers requires certain considerations. We will elaborate on these considerations and are there best practices? The development from reference centers into (virtual) networks and even thinktanks is a precarious process of which is making its way from infancy to adulthood.