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Journal articles on the topic 'Offline stabilization'
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Sadeghi Bogar, Mohsen, Jan Wolf, Daniel Sebastian Jens Wolz, Robert Seidel-Greiff, Evgenia Dmitrieva, Noel Israel, Marco Rosenkranz, Thomas Behnisch, Michael Thomas Müller, and Maik Gude. "Sensitivity of Offline and Inline Indicators for Fiber Stretching in Continuous Polyacrylonitrile Stabilization." Fibers 11, no. 8 (August 4, 2023): 68. http://dx.doi.org/10.3390/fib11080068.
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In carbon fiber (CF) production, the stabilization process step is the most energy- and time-consuming step in comparison with carbonization and graphitization. To develop optimization routes for energy and productivity, the stabilization needs to be monitored continuously via inline analysis methods. To prognose the evolution of high-performance CF, the density of stabilized fibers has been identified as a robust pre-indicator. As the offline analysis of density is not feasible for inline analysis, a density-soft sensor based on the stabilization indices of Fourier Transform Infrared spectrum (FTIR)-analysis and Electron Paramagnetic Resonance (EPR) Spectroscopy could potentially be used for inline monitoring. In this study, a Polyacrylonitrile-based precursor fiber (PF) stabilized in a continuous thermomechanical stabilization line with varying stretching profiles was incrementally analyzed using density, FTIR-based relative cyclization index (RCI), and EPR-based free radical concentration (FRC). Our findings show RCI and EPR dependencies for density, correlated for RCI with sensitivity by stretching to cubic model parameters, while FRC exhibits linear relationships. Therefore, this study identifies two possible soft sensors for inline density measurement, enabling autonomous energy optimization within industry 4.0-based process systems.
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Graf, Heike. "Media Practices and Forced Migration: Trust Online and Offline." Media and Communication 6, no. 2 (June 29, 2018): 149–57. http://dx.doi.org/10.17645/mac.v6i2.1281.
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This article explores the relationship between online and offline practices in the special case of forced migration. By applying a central category in social relations, trust/distrust as developed by Niklas Luhmann, this article contributes to the understanding of forced migration in the digital age. It presupposes that, without a strategy of trust, it would be almost impossible to cope with situations of unfamiliarity and uncertainty. By interviewing refugees, the question is in what contexts the refugee recognizes that they can trust (or not). The article concludes that through the combination of on- and offline communication practices, more varied mechanisms for the creation and stabilization of trust are provided. In contexts of unfamiliarity, interpersonal relations with the native inhabitants play an important role in bridging online and offline worlds.
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Anuchin, Alecksey, Galina L. Demidova, Chen Hao, Alexandr Zharkov, Andrei Bogdanov, and Václav Šmídl. "Continuous Control Set Model Predictive Control of a Switch Reluctance Drive Using Lookup Tables." Energies 13, no. 13 (June 29, 2020): 3317. http://dx.doi.org/10.3390/en13133317.
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A problem of the switched reluctance drive is its natural torque pulsations, which are partially solved with finite control set model predictive control strategies. However, the continuous control set model predictive control, required for precise torque stabilization and predictable power converter behavior, needs sufficient computation resources, thus limiting its practical implementation. The proposed model predictive control strategy utilizes offline processing of the magnetization surface of the switched reluctance motor. This helps to obtain precalculated current references for each torque command and rotor angular position in the offline mode. In online mode, the model predictive control strategy implements the current commands using the magnetization surface for fast evaluation of the required voltage command for the power converter. The proposed strategy needs only two lookup table operations requiring very small computation time, making instant execution of the whole control system possible and thereby minimizing the control delay. The proposed solution was examined using a simulation model, which showed precise and rapid torque stabilization below rated speed.
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Kummer, K. D., and W. F. Geiger. "Stabilization of Activated Sludge Processes During Wet Weather Flow through Microscreening." Water Science and Technology 29, no. 1-2 (January 1, 1994): 393–99. http://dx.doi.org/10.2166/wst.1994.0687.
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In the activated sludge process, between the aeration tank and the final clarifier, offline microscreening is introduced to separate activated sludge and purified water. The intention is to reduce the drifting of activated sludge from the aeration tank into the final clarifier. Sludge drifting usually occurs during wet weather flow loading of the treatment facility and can cause higher concentrations of ammonia and suspended solids in the effluent. Laboratory and half-technical scale experiments demonstrate that microscreening is suitable for this application. It is expected that the operational stability of activated sludge processes could be improved significantly by this process modification.
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Al-Sharman, Alham, and Catherine F. Siengsukon. "Sleep Enhances Learning of a Functional Motor Task in Young Adults." Physical Therapy 93, no. 12 (December 1, 2013): 1625–35. http://dx.doi.org/10.2522/ptj.20120502.
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Background Sleep has been demonstrated to enhance simple motor skill learning “offline” in young adults. “Offline learning” refers to either the stabilization or the enhancement of a memory through the passage of time without additional practice. It remains unclear whether a functional motor task will benefit from sleep to produce offline motor skill enhancement. Physical therapists often teach clients functional motor skills; therefore, it is important to understand how sleep affects learning of these skills. Objective The purpose of this study was to determine whether sleep enhances the learning of a functional motor task. Design A prospective, cross-sectional, repeated-measures design was used. Methods Young participants who were healthy (N=24) were randomly assigned to either a sleep group or a no-sleep group. The sleep group practiced a novel walking task in the evening and underwent retention testing the following morning, and the no-sleep group practiced the task in the morning and underwent retention testing in the evening. Outcome measures included time around the walking path and spatiotemporal gait parameters. Results Only participants who slept after practicing the novel walking task demonstrated a significant offline improvement in performance. Compared with the no-sleep group, participants in the sleep group demonstrated a significant decrease in the time around the walking path, an increase in tandem velocity, an increase in tandem step length, and a decline in tandem step time. Limitations Time-of-day effect and inability to ensure a certain amount of sleep quantity and quality of participants were limitations of the study. Conclusions This study is the first to provide evidence that sleep facilitates learning clinically relevant functional motor tasks. Sleep is an important factor that physical therapists should consider when teaching clients motor skills.
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Zhou, Xiangyang, Hao Gao, Yuan Jia, Lingling Li, Libo Zhao, and Ruifang Yu. "Parameter Optimization on FNN/PID Compound Controller for a Three-Axis Inertially Stabilized Platform for Aerial Remote Sensing Applications." Journal of Sensors 2019 (March 26, 2019): 1–15. http://dx.doi.org/10.1155/2019/5067081.
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This paper presents a composite parameter optimization method based on the chaos particle swarm optimization and the back propagation algorithms for a fuzzy neural network/proportion integration differentiation compound controller, which is applied for an aerial inertially stabilized platform for aerial remote sensing applications. Firstly, a compound controller combining both the adaptive fuzzy neural network and traditional PID control methods is developed to deal with the contradiction between the control precision and robustness due to disturbances. Then, on the basis of both the chaos particle swarm optimization and the back propagation compound algorithms, the parameters of the fuzzy neural network/PID compound controller are optimized offline and fine-tuned online, respectively. In this way, the compound controller can achieve good adaptive convergence so as to get high stabilization precision under the multisource dynamic disturbance environment. To verify the method, the simulations are carried out. The results show that the composite parameter optimization method can effectively enhance the convergence of the controller, by which the stabilization precision and disturbance rejection capability of the proposed fuzzy neural network/PID compound controller are improved obviously.
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Sofyan Fadly, Eby, and Jian Budiarto. "Aplikasi Evaluasi Perkembangan Latihan Atlet Panahan Menggunakan Progressive Web Application." JTIM : Jurnal Teknologi Informasi dan Multimedia 1, no. 1 (May 4, 2019): 8–13. http://dx.doi.org/10.35746/jtim.v1i1.6.
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Arrihu Archery is one of the archery clubs in the city of Mataram. Before taking the test to increase the level, participants will take part in the stabilization exercise in preparation for the exam. The problem faced was that the exercise carried out took a long time and the trainers had difficulty in monitoring the progress of the participants. This writing aims to accelerate the exercise and make it easier to monitor the training of participants. Therefore, it is necessary to build an Application to Evaluate the Development of Archery Athlete Exercises using Progressive Web Application. The design of this system is done by the waterfall methodology, which is a system development method that begins with planning, system design, making Web Service APIs, and creating Service Workers in the Progressive Web App application. The results that have been achieved in this study are the creation of applications to assist the stabilization training process and assist in monitoring the progress of trainees. This application is able to cache and be able to display pages offline. This application runs well on the google chrome browser version 43+
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Xue, Kaijia, Congqing Wang, Zhiyu Li, and Hanxin Chen. "Online Adaptive Error Compensation SVM-Based Sliding Mode Control of an Unmanned Aerial Vehicle." International Journal of Aerospace Engineering 2016 (2016): 1–14. http://dx.doi.org/10.1155/2016/8407491.
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Unmanned Aerial Vehicle (UAV) is a nonlinear dynamic system with uncertainties and noises. Therefore, an appropriate control system has an obligation to ensure the stabilization and navigation of UAV. This paper mainly discusses the control problem of quad-rotor UAV system, which is influenced by unknown parameters and noises. Besides, a sliding mode control based on online adaptive error compensation support vector machine (SVM) is proposed for stabilizing quad-rotor UAV system. Sliding mode controller is established through analyzing quad-rotor dynamics model in which the unknown parameters are computed by offline SVM. During this process, the online adaptive error compensation SVM method is applied in this paper. As modeling errors and noises both exist in the process of flight, the offline SVM one-time mode cannot predict the uncertainties and noises accurately. The control law is adjusted in real-time by introducing new training sample data to online adaptive SVM in the control process, so that the stability and robustness of flight are ensured. It can be demonstrated through the simulation experiments that the UAV that joined online adaptive SVM can track the changing path faster according to its dynamic model. Consequently, the proposed method that is proved has the better control effect in the UAV system.
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Yapanto, Alvian Mohamad. "Flail Chest: A Literature Review." Eduvest - Journal of Universal Studies 2, no. 4 (April 18, 2022): 660–72. http://dx.doi.org/10.59188/eduvest.v2i4.428.
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This study aims to make a review about flail chest management so this can be a simple and useful reference for surgeons to make a decision for flail chest management decisions. The research method used in this research is descriptive qualitative method. The type of data used in this study is qualitative data, which is categorized into two types, namely primary data and secondary data. Sources of data obtained through library research techniques (library studies) which refers to sources available both online and offline such as: scientific journals, books and news sourced from trusted sources. From the results of research and discussion concluded that early surgical stabilization of rib fracture has better outcome in the cases of ribs fracture which are severe enough
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Cheng, Yingying, Bo Xie, and Keyu An. "Analysis of Omni-Channel Evolution Game Strategy for E-Commerce Enterprises in the Context of Online and Offline Integration." Systems 11, no. 7 (June 23, 2023): 321. http://dx.doi.org/10.3390/systems11070321.
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With the upgrading of people’s consumption patterns, the omni-channel supply chain becomes the mainstream form of e-commerce platform enterprise development. Aiming at two different e-commerce enterprises, we construct an evolutionary game model for enterprises’ “online+offline” omni-channel construction strategy by self-build or cooperating with brick-and-mortar stores. It is based on the Stackelberg and Cournot competition model, combined with the omni-channel pricing strategy, using the theory of perfect rationality and bounded rationality, and combing the non-cooperative game and evolutionary game to realize. Moreover, the evolutionary game process is simulated. Through the dynamic changes of the system, the strategy selection behavior mechanism of the retail channel subjects is deeply analyzed. It is found that enterprises’ strategy choices are influenced by both competitors and profits, and evolutionary stabilization strategies are not unique. In addition, changes in consumer loyalty, physical feelings, and sharing ratio during the evolutionary process will affect the stability rate of enterprises’ behavioral choices.
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Ramachandran, Anjali, Rabee Rustum, and Adebayo J. Adeloye. "Review of Anaerobic Digestion Modeling and Optimization Using Nature-Inspired Techniques." Processes 7, no. 12 (December 13, 2019): 953. http://dx.doi.org/10.3390/pr7120953.
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Although it is a well-researched topic, the complexity, time for process stabilization, and economic factors related to anaerobic digestion call for simulation of the process offline with the help of computer models. Nature-inspired techniques are a recently developed branch of artificial intelligence wherein knowledge is transferred from natural systems to engineered systems. For soft computing applications, nature-inspired techniques have several advantages, including scope for parallel computing, dynamic behavior, and self-organization. This paper presents a comprehensive review of such techniques and their application in anaerobic digestion modeling. We compiled and synthetized the literature on the applications of nature-inspired techniques applied to anaerobic digestion. These techniques provide a balance between diversity and speed of arrival at the optimal solution, which has stimulated their use in anaerobic digestion modeling.
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M., Meenakshi, and M. Seetharama Bhat. "Real-Time Fixed-Order LateralH2Controller for Micro Air Vehicle." Journal of Control Science and Engineering 2011 (2011): 1–15. http://dx.doi.org/10.1155/2011/594086.
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This paper presents the design and development of a fixed low-order, robustH2controller for a micro air vehicle (MAV) named Sarika-2. The controller synthesis uses strengthened discrete optimal projection equations and frequency-dependent performance index to achieve robust performance and stability. A single fixed gain low-order dynamic controller provides simultaneous stabilization, disturbance rejection, and sensor noise attenuation over the entire flight speed range of 16 m/sec to 26 m/sec. Comparative study indicates that the low-orderH2-controller achieves robust performance levels similar to that of full order controller. Subsequently, the controller is implemented on a digital signal processor-based flight computer and is validated through the real time hardware in loop simulation. The responses obtained with hardware in loop simulation compares well with those obtained from the offline simulation.
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Ernala, Sindhu Kiranmai, Jordyn Seybolt, Dong Whi Yoo, Michael L. Birnbaum, John M. Kane, and Munmun De Choudhury. "The Reintegration Journey Following a Psychiatric Hospitalization: Examining the Role of Social Technologies." Proceedings of the ACM on Human-Computer Interaction 6, CSCW1 (March 30, 2022): 1–31. http://dx.doi.org/10.1145/3512969.
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For people diagnosed with mental health conditions, psychiatric hospitalization is a major life transition, involving clinical treatment, crisis stabilization and loss of access of social networks and technology. The period after hospitalization involves not only management of the condition and clinical recovery but also re-establishing social connections and getting back to social and vocational roles for successful reintegration ? a significant portion of which is mediated by social technology. However, little is known about how people get back to social lives after psychiatric hospitalization and the role social technology plays during the reintegration process. We address this gap through an interview study with 19 individuals who experienced psychiatric hospitalization in the recent past. Our findings shed light on how people's offline and online social lives are deeply intertwined with management of the mental health condition after hospitalization. We find that social technology supports reintegration journeys after hospitalization as well as presents certain obstacles. We discuss the role of social technology in significant life transitions such as reintegration and conclude with implications for social computing research, platform design and clinical care.
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Wick, Maximilian, Bastian Lehrheuer, Thivaharan Albin, Jakob Andert, and Stefan Pischinger. "Decoupling of consecutive gasoline controlled auto-ignition combustion cycles by field programmable gate array based real-time cylinder pressure analysis." International Journal of Engine Research 19, no. 2 (April 25, 2017): 153–67. http://dx.doi.org/10.1177/1468087417704342.
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Gasoline controlled auto-ignition combustion offers high potential for CO2 emission reduction, but faces challenges regarding combustion stability and high sensitivity to changing boundary conditions. Combustion chamber recirculation allows a wide operation range, but results in a strong coupling of consecutive cycles due to residuals that are transferred to the subsequent combustion cycle. The cycle coupling leads to phases of unstable operation with reduced efficiency and increased emission levels. State-of-the-art control algorithms use data-driven models of gasoline controlled auto-ignition combustion to achieve cycle-to-cycle control of the process or use offline calibration and optimization. A closed-loop control is proposed and implemented on a rapid control prototyping engine control unit. The control algorithm continuously calculates the current residual fuel in the combustion chamber. The heat release is observed and compared with the theoretical heat release of the injected fuel mass. The rate of unburned fuel mass transferred to the subsequent cycle is calculated offline by a detailed gas exchange model. Based on this information, the control algorithm adapts the injected fuel quantity for each cycle individually using an inverse injector model. In this article, a concept for decoupling consecutive cycles is presented to reduce the deviations of the indicated mean effective pressure and thus the heat release. Unstable sequences are analyzed in the time domain, and unburned residuals are identified as a strong correlating factor for consecutive cycles. Using real-time cylinder pressure analysis based on a field programmable gate array enables the online calculation of unburned residual fuel. Based on this calculation, the injection of each cycle can be adapted individually to decouple consecutive cycles and avoid unstable operation. The results of the control algorithm and the stabilization of the gasoline controlled auto-ignition combustion are validated using a single-cylinder research engine and compared to steady-state operation.
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Zhang, Z., D. Wang, S. Feng, Z. Ye, T. Zhou, Z. Zheng, F. Wang, et al. "A portable neutron gamma discrimination detector based on NaIL and SiPM." Journal of Instrumentation 17, no. 06 (June 1, 2022): T06005. http://dx.doi.org/10.1088/1748-0221/17/06/t06005.
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Abstract neutron-gamma detection technology is widely used in nuclear physics, high-energy physics, radiation medicine, and other fields. A NaIL scintillator coupled with a silicon photomultiplier (SiPM) can form a neutron-gamma detector with excellent discrimination, small size, and low cost. However, the performances of a NaIL scintillator and SiPM are affected by temperature, which leads to a shift in energy spectrum and deterioration in neutron-gamma discrimination. Most of the current studies have used digitizers to store data and analyze detector energy spectrum and waveform characteristics offline to eliminate temperature dependence. In this study, a small neutron-gamma detector was constructed using NaIL scintillators, SiPM, and circuits developed in the laboratory. Online calibration of the ARM processor eliminates the temperature dependence of the detector's energy spectrum and neutron-gamma discrimination. Automatic energy spectrum stabilization and good neutron-gamma discrimination were achieved in a wide temperature range. The test results show that the peak shift of the 137Cs 662 keV full-energy peak of the detector is reduced from 5.3% to 0.4% at 0–50°C. After the online correction of the temperature feedback PSD parameters, the figure of merit at 45°C is 40% higher than that before the correction, and the detector's figure of merit at 0–50°C is maintained above 3.4.
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Colorado, Julian D., Natalia Cera-Bornacelli, Juan S. Caldas, Eliel Petro, Maria C. Rebolledo, David Cuellar, Francisco Calderon, Ivan F. Mondragon, and Andres Jaramillo-Botero. "Estimation of Nitrogen in Rice Crops from UAV-Captured Images." Remote Sensing 12, no. 20 (October 16, 2020): 3396. http://dx.doi.org/10.3390/rs12203396.
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Leaf nitrogen (N) directly correlates to chlorophyll production, affecting crop growth and yield. Farmers use soil plant analysis development (SPAD) devices to calculate the amount of chlorophyll present in plants. However, monitoring large-scale crops using SPAD is prohibitively time-consuming and demanding. This paper presents an unmanned aerial vehicle (UAV) solution for estimating leaf N content in rice crops, from multispectral imagery. Our contribution is twofold: (i) a novel trajectory control strategy to reduce the angular wind-induced perturbations that affect image sampling accuracy during UAV flight, and (ii) machine learning models to estimate the canopy N via vegetation indices (VIs) obtained from the aerial imagery. This approach integrates an image processing algorithm using the GrabCut segmentation method with a guided filtering refinement process, to calculate the VIs according to the plots of interest. Three machine learning methods based on multivariable linear regressions (MLR), support vector machines (SVM), and neural networks (NN), were applied and compared through the entire phonological cycle of the crop: vegetative (V), reproductive (R), and ripening (Ri). Correlations were obtained by comparing our methods against an assembled ground-truth of SPAD measurements. The higher N correlations were achieved with NN: 0.98 (V), 0.94 (R), and 0.89 (Ri). We claim that the proposed UAV stabilization control algorithm significantly improves on the N-to-SPAD correlations by minimizing wind perturbations in real-time and reducing the need for offline image corrections.
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Ahmed, Shady E., and Omer San. "Breaking the Kolmogorov Barrier in Model Reduction of Fluid Flows." Fluids 5, no. 1 (February 18, 2020): 26. http://dx.doi.org/10.3390/fluids5010026.
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Turbulence modeling has been always a challenge, given the degree of underlying spatial and temporal complexity. In this paper, we propose the use of a partitioned reduced order modeling (ROM) approach for efficient and effective approximation of turbulent flows. A piecewise linear subspace is tailored to capture the fine flow details in addition to the larger scales. We test the partitioned ROM for a decaying two-dimensional (2D) turbulent flow, known as 2D Kraichnan turbulence. The flow is initiated using an array of random vortices, corresponding to an arbitrary energy spectrum. We show that partitioning produces more accurate and stable results than standard ROM based on a global application of modal decomposition techniques. We also demonstrate the predictive capability of partitioned ROM through an energy spectrum analysis, where the recovered energy spectrum significantly converges to the full order model’s statistics with increased partitioning. Although the proposed approach incurs increased memory requirements to store the local basis functions for each partition, we emphasize that it permits the construction of more compact ROMs (i.e., of smaller dimension) with comparable accuracy, which in turn significantly reduces the online computational burden. Therefore, we consider that partitioning acts as a converter which reduces the cost of online deployment at the expense of offline and memory costs. Finally, we investigate the application of closure modeling to account for the effects of modal truncation on ROM dynamics. We illustrate that closure techniques can help to stabilize the results in the inertial range, but over-stabilization might take place in the dissipative range.
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Jones, Andrew D., William D. Collins, James Edmonds, Margaret S. Torn, Anthony Janetos, Katherine V. Calvin, Allison Thomson, et al. "Greenhouse Gas Policy Influences Climate via Direct Effects of Land-Use Change." Journal of Climate 26, no. 11 (May 31, 2013): 3657–70. http://dx.doi.org/10.1175/jcli-d-12-00377.1.
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Abstract Proposed climate mitigation measures do not account for direct biophysical climate impacts of land-use change (LUC), nor do the stabilization targets modeled for phase 5 of the Coupled Model Intercomparison Project (CMIP5) representative concentration pathways (RCPs). To examine the significance of such effects on global and regional patterns of climate change, a baseline and an alternative scenario of future anthropogenic activity are simulated within the Integrated Earth System Model, which couples the Global Change Assessment Model, Global Land-Use Model, and Community Earth System Model. The alternative scenario has high biofuel utilization and approximately 50% less global forest cover than the baseline, standard RCP4.5 scenario. Both scenarios stabilize radiative forcing from atmospheric constituents at 4.5 W m−2 by 2100. Thus, differences between their climate predictions quantify the biophysical effects of LUC. Offline radiative transfer and land model simulations are also utilized to identify forcing and feedback mechanisms driving the coupled response. Boreal deforestation is found to strongly influence climate because of increased albedo coupled with a regional-scale water vapor feedback. Globally, the alternative scenario yields a twenty-first-century warming trend that is 0.5°C cooler than baseline, driven by a 1 W m−2 mean decrease in radiative forcing that is distributed unevenly around the globe. Some regions are cooler in the alternative scenario than in 2005. These results demonstrate that neither climate change nor actual radiative forcing is uniquely related to atmospheric forcing targets such as those found in the RCPs but rather depend on particulars of the socioeconomic pathways followed to meet each target.
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Permana, Irvan, and Karina Gan. "Social construction of technology (SCoT) from generation X’s shopping experiences to omnichannel as new way of shopping." Bricolage : Jurnal Magister Ilmu Komunikasi 8, no. 2 (September 1, 2022): 141. http://dx.doi.org/10.30813/bricolage.v8i2.3338.
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<p><em>Omnichannel is considered a new way of shopping that integrates online and offline methods to offer seamless shopping experiences. Omnichannel requires consumers adaptation to use the internet, mobile devices, and social media as tools for seamless shopping experiences. Based on 2021 YouGov’s report on omnichannel retail, 83% of Indonesians already used dual channels to shop, including generation X. How does generation X accept omnichannel and its technology as a new way of shopping? Using Social Construction of Technology (SCoT) theory, generation X is positioned as a relevant social group, and their interpretative flexibility on how they give meaning to omnichannel as a new way of shopping will be analyzed; followed by understanding their closure or common agreement towards webrooming, showrooming, buying online pick-up in store, and buying online return in-store as the attributes of omnichannel; then finally analyzing their stabilization in accepting omnichannel as a new way of shopping. Using the</em><em> </em><em>interpretative phenomenological analysis, this research was conducted by interviewing generation X to understand their acceptance of omnichannel. The results of this research show that generation X has no hesitation to omnichannel, but they saw it as additional services rather than integration of seamless shopping experiences.</em></p><p><strong><em></em></strong><em><br /></em><em></em></p><p><em><br /></em></p>
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Sharma, Atul, Sushil Raut, Kohei Shimasaki, Taku Senoo, and Idaku Ishii. "Visual-Feedback-Based Frame-by-Frame Synchronization for 3000 fps Projector–Camera Visual Light Communication." Electronics 10, no. 14 (July 8, 2021): 1631. http://dx.doi.org/10.3390/electronics10141631.
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This paper proposes a novel method for synchronizing a high frame-rate (HFR) camera with an HFR projector, using a visual feedback-based synchronization algorithm for streaming video sequences in real time on a visible-light communication (VLC)-based system. The frame rates of the camera and projector are equal, and their phases are synchronized. A visual feedback-based synchronization algorithm is used to mitigate the complexities and stabilization issues of wire-based triggering for long-distance systems. The HFR projector projects a binary pattern modulated at 3000 fps. The HFR camera system operates at 3000 fps, which can capture and generate a delay signal to be given to the next camera clock cycle so that it matches the phase of the HFR projector. To test the synchronization performance, we used an HFR projector–camera-based VLC system in which the proposed synchronization algorithm provides maximum bandwidth utilization for the high-throughput transmission ability of the system and reduces data redundancy efficiently. The transmitter of the VLC system encodes the input video sequence into gray code, which is projected via high-definition multimedia interface streaming in the form of binary images 590 × 1060. At the receiver, a monochrome HFR camera can simultaneously capture and decode 12-bit 512 × 512 images in real time and reconstruct a color video sequence at 60 fps. The efficiency of the visual feedback-based synchronization algorithm is evaluated by streaming offline and live video sequences, using a VLC system with single and dual projectors, providing a multiple-projector-based system. The results show that the 3000 fps camera was successfully synchronized with a 3000 fps single-projector and a 1500 fps dual-projector system. It was confirmed that the synchronization algorithm can also be applied to VLC systems, autonomous vehicles, and surveillance applications.
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Alla, Alessandro, Dante Kalise, and Valeria Simoncini. "State-dependent Riccati equation feedback stabilization for nonlinear PDEs." Advances in Computational Mathematics 49, no. 1 (February 2023). http://dx.doi.org/10.1007/s10444-022-09998-4.
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AbstractThe synthesis of suboptimal feedback laws for controlling nonlinear dynamics arising from semi-discretized PDEs is studied. An approach based on the State-dependent Riccati Equation (SDRE) is presented for 2 and ∞ control problems. Depending on the nonlinearity and the dimension of the resulting problem, offline, online, and hybrid offline-online alternatives to the SDRE synthesis are proposed. The hybrid offline-online SDRE method reduces to the sequential solution of Lyapunov equations, effectively enabling the computation of suboptimal feedback controls for two-dimensional PDEs. Numerical tests for the Sine-Gordon, degenerate Zeldovich, and viscous Burgers’ PDEs are presented, providing a thorough experimental assessment of the proposed methodology.
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Lin, Yegui, and Kexin Xing. "Visual servo optimization stabilization of nonholonomic mobile robots based on control Lyapunov functions." Measurement and Control, August 23, 2020, 002029402094496. http://dx.doi.org/10.1177/0020294020944960.
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This study considers the visual stabilization problem of nonholonomic mobile robots and proposes a novel optimization stabilization method for visual servo control of nonholonomic mobile robots with monocular cameras fixed onboard. The main idea of the method is to utilize control Lyapunov functions of discrete-time nonlinear systems to design a family of explicit stabilization control laws of the visual servo error system. The parameters of the control laws can indirectly reflect the performance of the visual servo controllers. Then taking account of visibility constraints and actuator limitations, a set of optimal parameters of the control laws is calculated by offline solving a constrained finite horizon optimal control problem. Moreover, the stabilization results on the optimal visual servo controller are established based on the properties of control Lyapunov functions. Finally, some simulation experiments are used to illustrate and evaluate the performance of the visual servo control scheme proposed here.
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Luchetti, A., M. Zanetti, D. Kalkofen, and M. De Cecco. "Stabilization of spherical videos based on feature uncertainty." Visual Computer, July 9, 2022. http://dx.doi.org/10.1007/s00371-022-02578-z.
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AbstractNowadays the trend is to acquire and share information in an immersive and natural way with new technologies such as Virtual Reality (VR) and 360$$^{\circ }$$ ∘ video. However, the use of 360$$^{\circ }$$ ∘ video, even more the use of VR head-mounted display, can generate general discomfort (“cybersickness”) and one factor is the video shaking. In this work, we developed a method to make the viewing of 360$$^{\circ }$$ ∘ video smoother and more comfortable to watch. First, the rotations are obtained with an innovative technique using a Particle Swarm Optimization algorithm considering the uncertainty estimation among features. In addition, a modified Chauvenet criterion is used to find and suppress outliers features from the algorithm. Afterward, a time-weighted color filter is applied to each frame in order to handle also videos with small translational jitter, rolling shutter wobble, parallax, and lens deformation. Thanks to our complete offline stabilization process, we achieved good-quality results in terms of video stabilization. Achieving better robustness compared to other works. The method was validated using virtual and real 360$$^{\circ }$$ ∘ video data of a mine environment acquired by a drone. Finally, a user study based on a subjective and standard Simulator Sickness Questionnaire was submitted to quantify simulator sickness before and after the stabilization process. The questionnaire underlined alleviation of cybersickness using stabilized videos with our approach
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Brown, James O., Alex Chatburn, David L. Wright, and Maarten A. Immink. "A Single Session of Mindfulness Meditation Expedites Immediate Motor Memory Consolidation to Improve Wakeful Offline Learning." Journal of Motor Learning and Development, 2022, 1–26. http://dx.doi.org/10.1123/jmld.2022-0016.
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Posttraining meditation has been shown to promote wakeful memory stabilization of explicit motor sequence information in learners who are experienced meditators. We investigated the effect of single-session mindfulness meditation on wakeful and sleep-dependent forms of implicit motor memory consolidation in meditation naïve adults. Immediately after training with a target implicit motor sequence, participants (N = 20, eight females, 23.9 ± 3.3 years) completed either a 10-min mindfulness meditation (N = 10) or a control listening task before exposure to task interference induced by training with a novel implicit sequence. Target sequence performance was tested following 5-hr wakeful and 15-hr postsleep periods. Bayesian inference was applied to group comparisons of mean reaction time (RT) changes across training, interference, wakeful, and postsleep timepoints. Relative to control conditions, posttraining meditation reduced RT slowing between target sequence training and interference sequence introduction (BF10 [Bayes factors] = 6.61) and supported RT performance gains over the wakeful period (BF10 = 8.34). No group differences in postsleep RT performance were evident (BF10 = 0.38). These findings illustrate that posttraining mindfulness meditation expedites wakeful, but not sleep-dependent, offline learning with implicit motor sequences. Previous meditation experience is not required to obtain wakeful consolidation gains from posttraining mindfulness meditation.
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Kianfar, Armin, and Mahmoud I. Hussein. "Phononic-subsurface flow stabilization by subwavelength locally resonant metamaterials." New Journal of Physics, April 11, 2023. http://dx.doi.org/10.1088/1367-2630/accbe5.
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Abstract The interactions between a solid surface and a fluid flow underlie dynamical processes relevant to air, sea, and land vehicle performance and numerous other technologies. Key among these processes are unstable flow disturbances that contribute to fundamental transformations in the flow field. Precise control of these disturbances is possible by introducing a phononic subsurface (PSub). This comprises locally attaching a finite phononic structure perpendicular to an elastic surface exposed to the flowing fluid. This structure experiences ongoing excitation by an unstable flow mode, or more than one mode, traveling in conjunction with the mean flow. The excitation generates small deformations at the surface that trigger elastic wave propagation within the structure, traveling away from the flow and reflecting at the end of the structure to return to the fluid-structure interface and back into the flow. By targeted tuning of the unit-cell and finite-structure characteristics of the PSub, the returning waves may be devised to resonate and reenter the flow out of phase, leading to significant destructive interference of the continuously incoming flow waves near the surface and subsequently to their attenuation over the spatial extent of the control region. This entire mechanism is passive, responsive, and engineered offline without needing coupled fluid-structure simulations; only the flow instability's frequency, wavelength, and overall modal characteristics must be known. Disturbance stabilization in a wall-bounded transitional flow leads to delay in laminar-to-turbulent transition and reduction in skin-friction drag. Destabilization is also possible by alternatively designing the PSub to induce constructive interference, which is beneficial for delaying flow separation and enhancing chemical mixing and combustion. In this paper, we present a PSub in the form of a locally resonant elastic metamaterial, designed to operate in the elastic subwavelength regime and hence being significantly shorter in length compared to a phononic-crystal-based PSub. This is enabled by utilizing a sub-hybridization resonance. Using direct numerical simulations (DNS) of channel flows, both types of PSubs are investigated, and their controlled spatial and energetic influence on the wall-bounded flow behavior is demonstrated and analyzed. We show that the PSub's effect is spatially localized as intended, with a rapidly diminishing streamwise influence away from its location in the subsurface.
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Lebert, Jan, Namita Ravi, George Kensah, and Jan Christoph. "Real-Time Optical Mapping of Contracting Cardiac Tissues With GPU-Accelerated Numerical Motion Tracking." Frontiers in Cardiovascular Medicine 9 (May 18, 2022). http://dx.doi.org/10.3389/fcvm.2022.787627.
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Optical mapping of action potentials or calcium transients in contracting cardiac tissues are challenging because of the severe sensitivity of the measurements to motion. The measurements rely on the accurate numerical tracking and analysis of fluorescence changes emitted by the tissue as it moves, and inaccurate or no tracking can produce motion artifacts and lead to imprecise measurements that can prohibit the analysis of the data. Recently, it was demonstrated that numerical motion-tracking and -stabilization can effectively inhibit motion artifacts, allowing highly detailed simultaneous measurements of electrophysiological phenomena and tissue mechanics. However, the field of electromechanical optical mapping is still young and under development. To date, the technique is only used by a few laboratories, the processing of the video data is time-consuming and performed offline post-acquisition as it is associated with a considerable demand for computing power. In addition, a systematic review of numerical motion tracking algorithms applicable to optical mapping data is lacking. To address these issues, we evaluated 5 open-source numerical motion-tracking algorithms implemented on a graphics processing unit (GPU) and compared their performance when tracking and compensating motion and measuring optical traces in voltage- or calcium-sensitive optical mapping videos of contracting cardiac tissues. Using GPU-accelerated numerical motion tracking, the processing times necessary to analyze optical mapping videos become substantially reduced. We demonstrate that it is possible to track and stabilize motion and create motion-compensated optical maps in real-time with low-resolution (128 x 128 pixels) and high resolution (800 x 800 pixels) optical mapping videos acquired at 500 and 40 fps, respectively. We evaluated the tracking accuracies and motion-stabilization capabilities of the GPU-based algorithms on synthetic optical mapping videos, determined their sensitivity to fluorescence signals and noise, and demonstrate the efficacy of the Farnebäck algorithm with recordings of contracting human cardiac cell cultures and beating hearts from 3 different species (mouse, rabbit, pig) imaged with 4 different high-speed cameras. GPU-accelerated processing provides a substantial increase in processing speed, which could open the path for more widespread use of numerical motion tracking and stabilization algorithms during routine optical mapping studies.
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She, Buxin, Yuqing Dong, and Yilu Liu. "Time Delay of Wide Area Damping Control in Urban Power Grid: Model-Based Analysis and Data-Driven Compensation." Frontiers in Energy Research 10 (April 27, 2022). http://dx.doi.org/10.3389/fenrg.2022.895163.
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Due to the rapid development of economies, large urban cities consume an increasing amount of energy and have a higher requirement for power quality. Voltage source converter based high voltage direct current (VSC-HVDC) is a promising device to transmit clean power from remote regions to urban power systems, while also providing wide area damping control (WADC) for frequency stabilization. However, the time-delay naturally existing in the VSC-HVDC system may degrade the performance of WADC and even result in instability. To address this issue, this paper develops a time-delay correction control strategy for VSC-HVDC damping control in urban power grids. First, a small signal model of WADC is built to analyze the negative impacts of time delay. Then, a data-driven approach is proposed to compensate for the inherent time delay in VSC-HVDC damping control. The extensive training data will be generated under various disturbances. After offline training, the long short-term memory network (LSTM) can be implemented online to predict the actual frequency deviation based on real-time measurements. Finally, the proposed method is validated through MATLAB-Simulink in a two-area four-machine system. The results indicate that the data-driven compensation has a strong generalization ability for random delay time constants and can improve the performance of WADC significantly.
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Temporiti, Federico, Alessandra Calcagno, Stefania Coelli, Giorgia Marino, Roberto Gatti, Anna Maria Bianchi, and Manuela Galli. "Early sleep after action observation and motor imagery training boosts improvements in manual dexterity." Scientific Reports 13, no. 1 (February 14, 2023). http://dx.doi.org/10.1038/s41598-023-29820-5.
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AbstractThe systematic observation and imagination of actions promotes acquisition of motor skills. Furthermore, studies demonstrated that early sleep after practice enhances motor learning through an offline stabilization process. Here, we investigated behavioral effects and neurodynamical correlates of early sleep after action observation and motor imagery training (AO + MI-training) on motor learning in terms of manual dexterity. Forty-five healthy participants were randomized into three groups receiving a 3 week intervention consisting of AO + MI-training immediately before sleeping or AO + MI-training at least 12 h before sleeping or a control stimulation. AO + MI-training implied the observation and motor imagery of transitive manual dexterity tasks, whereas the control stimulation consisted of landscape video-clips observation. Manual dexterity was assessed using functional tests, kinematic and neurophysiological outcomes before and after the training and at 1-month follow-up. AO + MI-training improved manual dexterity, but subjects performing AO + MI-training followed by early sleep had significantly larger improvements than those undergoing the same training at least 12 h before sleeping. Behavioral findings were supported by neurodynamical correlates during motor performance and additional sleep-dependent benefits were also detected at 1 month follow-up. These findings introduce a new approach to enhance the acquisition of new motor skills or facilitate recovery in patients with motor impairments.
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Tóth-Fáber, Eszter, Dezso Nemeth, and Karolina Janacsek. "Lifespan developmental invariance in memory consolidation: evidence from procedural memory." PNAS Nexus, February 8, 2023. http://dx.doi.org/10.1093/pnasnexus/pgad037.
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Abstract Characterizing ontogenetic changes across the lifespan is a crucial tool in understanding neurocognitive functions. While age-related changes in learning and memory functions have been extensively characterized in the past decades, the lifespan trajectory of memory consolidation, a critical function that supports the stabilization and long-term retention of memories, is still poorly understood. Here we focus on this fundamental cognitive function and probe the consolidation of procedural memories that underlie cognitive, motor, and social skills and automatic behaviors. We used a lifespan approach: 255 participants aged between 7 and 76 performed a well-established procedural memory task in the same experimental design across the whole sample. This task enabled us to disentangle two critical processes in the procedural domain: statistical learning and general skill learning. The former is the ability to extract and learn predictable patterns of the environment, while the latter captures a general speed-up as learning progresses due to improved visuomotor coordination and other cognitive processes, independent of acquisition of the predictable patterns. To measure the consolidation of statistical and general skill knowledge, the task was administered in two sessions with a 24-hour delay between them. Here, we report successful retention of statistical knowledge with no differences across age groups. For general skill knowledge, offline improvement was observed over the delay period, and the degree of this improvement was also comparable across the age groups. Overall, our findings reveal age invariance in these two key aspects of procedural memory consolidation across the human lifespan.
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Chen, Zhe, Garrett J. Blair, Changliang Guo, Jim Zhou, Juan-Luis Romero-Sosa, Alicia Izquierdo, Peyman Golshani, Jason Cong, Daniel Aharoni, and Hugh T. Blair. "A hardware system for real time decoding of in vivo calcium imaging data." eLife 12 (January 24, 2023). http://dx.doi.org/10.7554/elife.78344.
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Epifluorescence miniature microscopes ('miniscopes') are widely used for in vivo calcium imaging of neural population activity. Imaging data is typically collected during a behavioral task and stored for later offline analysis, but emerging techniques for online imaging can support novel closed-loop experiments in which neural population activity is decoded in real time to trigger neurostimulation or sensory feedback. To achieve short feedback latencies, online imaging systems must be optimally designed to maximize computational speed and efficiency while minimizing errors in population decoding. Here we introduce DeCalciOn, an open-source device for real-time imaging and population decoding of in vivo calcium signals that is hardware compatible with all miniscopes that use the UCLA Data Acquisition (DAQ) interface. DeCalciOn performs online motion stabilization, neural enhancement, calcium trace extraction, and decoding of up to 1024 traces per frame at latencies of <50 ms after fluorescence photons arrive at the miniscope image sensor. We show that DeCalciOn can accurately decode the position of rats (n=12) running on a linear track from calcium fluorescence in the hippocampal CA1 layer, and can categorically classify behaviors performed by rats (n=2) during an instrumental task from calcium fluorescence in orbitofrontal cortex (OFC). DeCalciOn achieves high decoding accuracy at short latencies using innovations such as field-programmable gate array (FPGA) hardware for real time image processing and contour-free methods to efficiently extract calcium traces from sensor images. In summary, our system offers an affordable plug-and-play solution for real-time calcium imaging experiments in behaving animals.
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Janák, Vladislav, Luděk Bartoněk, Lumír Hrabálek, Jiří Keprt, and Jiří Charamza. "The prototype BS-II for computer measurement of biomechanical characteristics of the human cadaverous lumbar spine." Journal of Orthopaedic Surgery and Research 14, no. 1 (December 2019). http://dx.doi.org/10.1186/s13018-019-1463-8.
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Abstract Background The new second-generation computer system BS-II (Bio-Spine-II) based on the National Instruments’ development environment has been designed and constructed for evaluating the stability of various surgical fixative methods of the cadaverous lumbar spine (L1–L5). BS-II holds the measured sample using aluminum fixtures and using four computer-controlled stepper motors; it performs a circular movement (warm up of the specimen), programmatically driven extension (back bend), right and left lateral flexion (lateral bend), left and right axial torsion (rotation), and axial compression (pressure). Four strain gauges are used to measure the stiffness of the sample. The movement of individual components (vertebrae) is contactlessly monitored by two CCD (charge couple device) cameras. The obtained data are in digital form continuously stored in the computer memory for further processing. Methods The functionality of the equipment was verified on the cadaverous specimen of the human spine. The stiffness of the sample was measured by strain gauges, and the results were processed using linear regression analysis. Movements of vertebrae were determined by circular discs covered with appropriate patterns. The discs have been linked with the respective vertebrae and were contactlessly monitored by two CCD (charge couple device) cameras and evaluated using digital image processing methods and 2D digital FFT (fast Fourier transformation). Direction and displacement of the individual components were determined by the band of the calculated spectrum. The new device BS-II is controlled by a modifiable computer program designed in the National Instruments’ development environment which allows statistical processing of the sample, including its warming up. Results The computer system BS-II for measurement of biomechanical properties of the spine sample was designed. Functionality of the device was verified by implementation of LUMIR XLIF CAGE implant into a cadaver sample of the human spine. Comparison of the rigidity of the intact and stabilized sample is shown in the graphs of article. The achieved results contributed to certification of the implant into the surgical practice. Conclusion The designed computer BS-II system is designed for biomechanical measurements of the lumbar part of the human spine, especially for verification of surgical fixation methods. The system is based on the knowledge and experience with a manually operated measuring device designed by Palacky University Olomouc. The computer programmatic control allows the user to change the conditions and parameters of the measurement procedure in a planned way, which allows the results to be processed in, among other things, a statistical way. If suitable models are used (3D printing), the BS-II system can be used to verify procedures for surgical stabilization of the spine in the training of future doctors. The obtained data of stiffness and image information are stored in digital form and can be used for next offline sophisticated study of biomechanical properties of specimens (accurate vertebral geometry, statistical processing, 3D printing, etc.). The usefulness of the BS-II system is demonstrated in the case of biomechanical analysis of the implantation of LUMIR XLIF CAGE implant to a human cadaver specimen of the spine.