Artículos de revistas: "Closed loop operational envelop"

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Navalkar, Sachin T., Lars O. Bernhammer, Jurij Sodja, Edwin van Solingen, Gijs A. M. van Kuik y Jan-Willem van Wingerden. "Wind tunnel tests with combined pitch and free-floating flap control: data-driven iterative feedforward controller tuning". Wind Energy Science 1, n.º 2 (26 de octubre de 2016): 205–20. http://dx.doi.org/10.5194/wes-1-205-2016.

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Abstract. Wind turbine load alleviation has traditionally been addressed in the literature using either full-span pitch control, which has limited bandwidth, or trailing-edge flap control, which typically shows low control authority due to actuation constraints. This paper combines both methods and demonstrates the feasibility and advantages of such a combined control strategy on a scaled prototype in a series of wind tunnel tests. The pitchable blades of the test turbine are instrumented with free-floating flaps close to the tip, designed such that they aerodynamically magnify the low stroke of high-bandwidth actuators. The additional degree of freedom leads to aeroelastic coupling with the blade flexible modes. The inertia of the flaps was tuned such that instability occurs just beyond the operational envelope of the wind turbine; the system can however be stabilised using collocated closed-loop control. A feedforward controller is shown to be capable of significant reduction of the deterministic loads of the turbine. Iterative feedforward tuning, in combination with a stabilising feedback controller, is used to optimise the controller online in an automated manner, to maximise load reduction. Since the system is non-linear, the controller gains vary with wind speed; this paper also shows that iterative feedforward tuning is capable of generating the optimal gain schedule online.

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Madison, Richard, Abhinandan Jain, Christopher Lim y Mark Maimone. "Performance Characterization of a Rover Navigation Algorithm Using Large-Scale Simulation". Scientific Programming 15, n.º 2 (2007): 95–105. http://dx.doi.org/10.1155/2007/638280.

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Autonomous rover navigation is a critical technology for robotic exploration of Mars. Simulation allows more extensive testing of such technologies than would be possible with hardware test beds alone. A large number of simulations, running in parallel, can test an algorithm under many different operating conditions to quickly identify the operational envelope of the technology and identify failure modes that were not discovered in more limited testing. GESTALT is the autonomous navigation algorithm developed for NASA's Mars rovers. ROAMS is a rover simulator developed to support the Mars program. We have integrated GESTALT into ROAMS to test closed-loop, autonomous navigation in simulation. We have developed a prototype capability to run many copies of ROAMS in parallel on a supercomputer, varying input parameters to rapidly explore GESTALT's performance across a parameter space. Using these tools, we have demonstrated that large scale simulation can identify performance limits and unexpected behaviors in an algorithm. Such parallel simulation was able to test approximately 500 parameter combinations in the time required for a single test on a hardware test bed.

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Yang, Honghai, S. Khandekar y M. Groll. "Operational limit of closed loop pulsating heat pipes". Applied Thermal Engineering 28, n.º 1 (enero de 2008): 49–59. http://dx.doi.org/10.1016/j.applthermaleng.2007.01.033.

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4

Polley, J. A., S. Adibhatla y P. J. Hoffman. "Multivariate Turbofan Engine Control for Full Flight Envelope Operation". Journal of Engineering for Gas Turbines and Power 111, n.º 1 (1 de enero de 1989): 130–37. http://dx.doi.org/10.1115/1.3240211.

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The design of a full flight envelope nonlinear multivariable controller is described for a single-bypass variable-cycle jet engine. The nonlinear controller is obtained by using appropriate engine corrected parameters to schedule multivariable linear compensator gains designed at selected operating points of the flight envelope. The KQ (K-matrix compensator, Q-desired response) multivariable control design technique is used to design the compensators using linear state-space models obtained from a detailed nonlinear aerothermo model. The controller is implemented in the detailed nonlinear aerothermo model. The paper describes an example KQ compensator design, the corrected-parameter gain scheduling approach, and controller performance validation by nonlinear simulation. Computer simulations for sea-level static, and supersonic operating points are included to show the closed-loop transient performance in the presence of an acceleration fuel schedule.

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5

Chiu, Chui-Yu, Chen-Yang Cheng y Ting-Ying Wu. "Integrated Operational Model of Green Closed-Loop Supply Chain". Sustainability 13, n.º 11 (27 de mayo de 2021): 6041. http://dx.doi.org/10.3390/su13116041.

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Due to increasing environmental awareness, companies have started embracing the green supply chain concept to reduce waste of resources. Based on this increased awareness, an integrated green closed-loop supply chain has been developed, which integrates the forward supply chain and reverse supply chain. The reverse supply chain follows the same path as the forward supply chain in the reverse direction to recycle used products. Due to the uncertain quality of used products, not all products can be selected for recycling and reproduction, as the reduced yield might decrease the overall net income in the supply chain. The study develops an evaluation model to consider government subsidy, used product recycling rate, and quality of the used products to explore their impacts on the entire system. The results show that when the reproducibility rate of used raw materials decreases, the net income would also decrease accordingly. Furthermore, when government subsidy increases, the net income of the supply chain also increases accordingly. Similarly, when the recycling rate of used products increases, the net income also increases. As government subsidy affects the net income more than the recycling rate of used products, this research concludes that government subsidy is a key factor in the green closed-loop supply chain.

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Spinato, Giulia, Navid Borhani y John R. Thome. "Operational regimes in a closed loop pulsating heat pipe". International Journal of Thermal Sciences 102 (abril de 2016): 78–88. http://dx.doi.org/10.1016/j.ijthermalsci.2015.11.006.

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Liu, Bo, Jing Zhuo Shi y Xun Liu. "Variable Step-Length Efficiency Optimum Control of Traveling Wave Ultrasonic Motor System". Advanced Materials Research 383-390 (noviembre de 2011): 6484–89. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.6484.

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To achieve the operational efficiency maximization of ultrasonic motor system, this paper analyzes optimum control of the ultrasonic motor system’s efficiency including driving circuit, while the speed closed-loop control performance is ensured. Based on regulating characteristics of open-loop speed control and fuzzy control, two optimum control methods for regulating the changing step-length of driving voltage amplitude, to shorten the elapsed time of efficiency optimization process and to improve the general operational efficiency of motor system and the speed closed-loop control performance, are also analyzed. The effectiveness of the methods mentioned in this paper are reflected using experiments.

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Liu, Lang, Yutao Pu, Zhenwei Liu y Junjie Liu. "Analysis of Green Closed-Loop Supply Chain Efficiency under Generalized Stochastic Petri Nets". Sustainability 15, n.º 17 (1 de septiembre de 2023): 13181. http://dx.doi.org/10.3390/su151713181.

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In this paper, we aim to explore the operational performance of a green closed-loop supply chain under random events. A green closed-loop supply chain model based on generalized stochastic Petri nets (GSPN) is built using the Petri nets theory. According to the isomorphic relationship between GSPN and continuous-time Markov chains, the relevant Markov model is converted from GSPN, and the steady-state probability of the model is then calculated. Finally, the model is analyzed from the aspects of time performance and operation efficiency of each link. Compared to previous studies, this paper finds that: when the whole green closed-loop supply chain system reaches a dynamic equilibrium state, the product has a steady-state probability at all stages, and thus the overall operational performance of the system can be obtained; compared with the recycling of waste products, the green product takes a longer time in the production and distribution stages; since marketing, packaging processing, market feedback, and market demand formulation account for a high level of utilization throughout the life cycle of green products, decision makers need to focus on the supervision and management of these links. Managers of green closed-loop supply chain systems need to adjust their decision-making strategies in a timely manner according to the performance level of the system in the steady state to realize the efficient operation of the system. This paper not only provides theoretical support for the improvement of the operational efficiency of green closed-loop supply chain system, but also provides new ideas for the research of green closed-loop supply chain operation mode.

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Morton, Jeremy, Tim A. Wheeler y Mykel J. Kochenderfer. "Closed-Loop Policies for Operational Tests of Safety-Critical Systems". IEEE Transactions on Intelligent Vehicles 3, n.º 3 (septiembre de 2018): 317–28. http://dx.doi.org/10.1109/tiv.2018.2843128.

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10

Lyshevski, S. E. "Non-linear multivariable flight control of aircraft". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 212, n.º 2 (1 de febrero de 1998): 137–44. http://dx.doi.org/10.1243/0954410981532207.

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Innovative design methods are needed for advanced aircraft in response to requirements towards substantial performance improvements. Functionally and operationally, the aircraft must be considered as the highly coupled non-linear multi-input multi-output system, i.e. the aerodynamics have to be mapped by non-linear differential or difference equations. To improve flying and handling qualities, to increase manœuvrability and to expand the operating envelope, an innovative optimization procedure is developed to design the constrained controllers for multi-input multi-output aircraft. In particular, a bounded control law is synthesized by employing the Hamilton-Jacobi theory, and the admissibility concept is used to study the stability of the resulting closed-loop system. The developed optimization procedure is applied to a non-linear ninth-order model of an AFTI/F-16 aircraft. A bounded controller is designed, and modelling results are presented to demonstrate the dynamic performance of the resulting closed-loop system.

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Leiter, Ákos, Edina Lami, Attila Hegyi, József Varga y László Bokor. "Closed-loop Orchestration for Cloud-native Mobile IPv6". Infocommunications journal 15, n.º 1 (2023): 44–54. http://dx.doi.org/10.36244/icj.2023.1.5.

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With the advent of Network Function Virtualization (NFV) and Software-Defined Networking (SDN), every network service type faces significant challenges induced by novel requirements. Mobile IPv6, the well-known IETF standard for network-level mobility management, is not an exemption. Cloud-native Mobile IPv6 has acquired several new capabilities due to the technological advancements of NFV/SDN evolution. This paper presents how automatic failover and scaling can be envisioned in the context of cloud-native Mobile IPv6 with closed-loop orchestration on the top of the Open Network Automation Platform. Numerical results are also presented to indicate the usefulness of the new operational features (failover, scaling) driven by the cloud-native approach and highlight the advantages of network automation in virtualized and softwarized environments.

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12

Guo, Yanning, Pengyu Wang, Guangfu Ma y Liangyue Wang. "Envelope oriented singularity robust steering law of control moment gyros for spacecraft attitude maneuver". Transactions of the Institute of Measurement and Control 41, n.º 4 (17 de julio de 2018): 954–62. http://dx.doi.org/10.1177/0142331218783237.

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The problem of steering pyramid control moment gyro (CMG) cluster for fast spacecraft attitude maneuver along eigenaxis is investigated. A novel steering law is proposed to continuously attempt to reduce the difference between the current gimbal angle and the desired one corresponding to the angular momentum envelop of the CMG cluster. The proposed steering law can be decomposed into two parts: the first one is a singularity robust term to keep maneuverability and produce control torque, and the other is a null motion term to rearrange the gimbal angles toward momentum envelope. By involving this steering law, it is expected to possess both rapid angular momentum exchange and singularity avoidance ability. In addition, by introducing a new limit vector on attitude error, classical cascade-saturation control algorithm is revised to guarantee spacecraft eigenaxis rotation. Both open-loop steering law test and closed-loop attitude maneuver simulations are performed to evaluate the efficacy of the proposed methods.

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Acharya, Priyamvada, Robert Edwards, Rory Henderson, Kartik Manne, Katayoun Mansouri, Katarzyna Janowska, Shana McDowell, Victoria Stalls, Megan Kopp y Barton Haynes. "How Does HIV Env Structure Informs Vaccine Design?" Microscopy and Microanalysis 26, S2 (30 de julio de 2020): 574–75. http://dx.doi.org/10.1017/s1431927620015135.

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BackgroundThe DHVI Division of Structural Biology seeks to use atomic level structural information for design of an effective HIV-1 vaccine. Through visualization of the HIV-1 envelope (Env) and its interactions with the human immune system, we obtain structural information that we translate into the rational development vaccine immunogensMethodsWe use negative stain electron microscopy (NSEM), cryo-electron microscopy (cryo-EM), and x-ray crystallography as the major structural techniques for visualization of HIV-1 Env, and combine these with biochemical and biophysical studies, as well as computational methods to obtain a basic understanding of the functions and interactions of the HIV-1 Env.Results:1.The DHVI NSEM pipeline runs on a daily basis to quality control vaccine immunogens for animal studies and other applications. Offering rapid sample turnover and economical operations, the NSEM pipeline is the most widely utilized resource of the DHVI Division of Structural Biology. Over the last year, the NSEM team has focused efforts on improving operational speed and data processing allowing high-quality visualization of a large variety of samples including HIV-1 Env immunogens, antibodies, nanoparticles, and VLPs. In the last year we have also expanded our NSEM studies to the analyses of serum samples and mucosal fluids.2.To understand the mechanism of HIV-1 entry we have determined structures of HIV-1 entry intermediates. We have determined a 3.8 Å resolution structure of a single CD4 bound to a closed HIV-1 Env trimer revealing new contacts of CD4 with Env. We have also structurally characterized an Env designed to prevent CD4-induced rearrangements by targeted disruption of an allosteric network modulating Env conformational changes.3.We have structurally characterized the HIV-1 glycan-V3 targeting DH270 Broadly Neutralizing Antibody Lineage. The structures revealed movements in the V1 loop and interactive glycans, shifts in antibody orientations, antibody VH-VL orientations, and antibody elbow angles, as the lineage progressed to maturation.4.We have solved a structure in complex with the HIV-1 Env immunogen Man5-enriched CH505.N279K.G458Y.SOSIP.664 of the unmutated common ancestor (UCA) of the HIV-1 CD4-binding site targeting CH235 Broadly Neutralizing Antibody Lineage. The structure revealed interactions of the N279K and G458Y mutations with the CDR L3 loop of CH235 UCA thus providing a structural understanding of the role of these mutations in facilitating binding to the CH235 UCA. (see also Henderson et al abstract)5.Using NSEM and cryo-EM we have characterized the structural properties of a novel class of 2G12-mimetic, yet non domain-swapped Fab dimer glycan-reactive (FDG) antibodies. These studies showed that the Fab-dimerized 2G12-like motif is more common than previously thought, and that creation of a Fab-dimerized paratope for an HIV-1 neutralizing antibody does not require VH domain-swapping.6.Finally, the structural team is an integral part of the CHAVD Kalma Immunogen Design Team, wherein we are defining the structural basis of bnAb affinity maturation to guide sequential immunogen design.Conclusions:These results highlight the power of structural information on HIV-1 vaccine design, from leveraging a basic understanding of HIV-1 entry mechanism for immunogen design, to rapid visualization of Env immunogens by NSEM for quality control, discovery of novel antibody interactions, and atomic level visualization of antibody/Env interactions.

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Quintanar-Guzmán, Serket, Somasundar Kannan, Adriana Aguilera-González, Miguel A. Olivares-Mendez y Holger Voos. "Operational space control of a lightweight robotic arm actuated by shape memory alloy wires: A comparative study". Journal of Intelligent Material Systems and Structures 30, n.º 9 (25 de agosto de 2017): 1368–84. http://dx.doi.org/10.1177/1045389x17721050.

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This article presents the design and control of a two-link lightweight robotic arm using shape memory alloy wires as actuators. Both a single-wire actuated system and an antagonistic configuration system are tested in open and closed loops. The mathematical model of the shape memory alloy wire, as well as the kinematics and dynamics of the robotic arm, are presented. The operational space control of the robotic arm is performed using a joint space control in the inner loop and closed-loop inverse kinematics in the outer loop. In order to choose the best joint space control approach, a comparative study of four different control approaches (proportional derivative, sliding mode, adaptive, and adaptive sliding mode control) is carried out for the proposed model. From this comparative analysis, the adaptive controller was chosen to perform operational space control. This control helps us to perform accurate positioning of the end-effector of shape memory alloy wire–based robotic arm. The complete operational space control was successfully tested through simulation studies performing position reference tracking in the end-effector space. Through simulation studies, the proposed control solution is successfully verified to control the hysteretic robotic arm.

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15

Khandekar, Sameer, Nicolas Dollinger y Manfred Groll. "Understanding operational regimes of closed loop pulsating heat pipes: an experimental study". Applied Thermal Engineering 23, n.º 6 (abril de 2003): 707–19. http://dx.doi.org/10.1016/s1359-4311(02)00237-5.

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Mani, Gopinath y G. Gopu. "Closed Loop Analysis of Bridgeless SEPIC Converter for Drive Application". International Journal of Power Electronics and Drive Systems (IJPEDS) 6, n.º 2 (1 de junio de 2015): 253. http://dx.doi.org/10.11591/ijpeds.v6.i2.pp253-259.

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In this paper closed loop analysis of Single phase AC-DC Bridgeless Single Ended Primary Inductance Converter (SEPIC) for Power Factor Correction (PFC) rectifier is analyzed. In this topology the absence of an input diode bridge and the due to presence of two semiconductor switches in the current flowing path during each switching cycle which will results in lesser conduction losses and improved thermal management compared to the conventional converters. In this paper the operational principles, Frequency analysis, and design equations of the proposed converter are described in detail. Performance of the proposed SEPIC PFC rectifier are carried out using Matlab Simulink software and results are presented.

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Williams, John y Robert M. Rice. "Navy High-Pressure Waterjet Closed-Loop Paint Stripping System". Journal of Ship Production 12, n.º 01 (1 de febrero de 1996): 59–66. http://dx.doi.org/10.5957/jsp.1996.12.1.59.

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The marine refurbishment industry currently utilizes abrasive blasting for hull coatings removal. These processes generate extreme amounts of waste material, which must be contained and disposed of properly. The cost of containment, the hazardous work environment and the amounts of hazardous waste produced are all significant disadvantages of the existing processes. Additionally, environmental regulations and safety standards are being introduced which demand new techniques for marine coatings removal. In light of these factors, the U.S. Navy's Naval Surface Warfare Center-Carderock Division entered into a joint initiative with the U.S. Air Force to introduce an alternative paint and marine growth removal method, including complete effluent recovery at the source. This system, using only high-pressure water, is semi-automatic and mobile. The system can operate independently in a dry dock without external utilities. In the end, the system will eliminate the current problems associated with coatings removal and reduce the overall operational costs.

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Camarillo, Karla, Ricardo Campa, Víctor Santibáñez y Javier Moreno-Valenzuela. "Stability analysis of the operational space control for industrial robots using their own joint velocity PI controllers". Robotica 26, n.º 6 (noviembre de 2008): 729–38. http://dx.doi.org/10.1017/s0263574708004335.

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SUMMARYOperational space control of industrial robots is addressed in this document. We analyze a two-loop hierarchical control with the resolved motion rate controller (RMRC) as outer loop and the joint velocity PI controller as inner loop; the latter is the typical velocity controller used in industrial robots. We prove, by the first time, that these simple controllers make the solutions of the closed-loop system uniformly ultimately bounded. Additionally, we give some simple guidelines for the selection of the control gains so as to ensure an explicit bound of the tracking error.

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Wang, Ningquan, Ruxiu Liu, Norh Asmare, Chia-Heng Chu, Ozgun Civelekoglu y A. Fatih Sarioglu. "Closed-loop feedback control of microfluidic cell manipulation via deep-learning integrated sensor networks". Lab on a Chip 21, n.º 10 (2021): 1916–28. http://dx.doi.org/10.1039/d1lc00076d.

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20

Paksoy, Turan, Tolga Bektaş y Eren Özceylan. "Operational and environmental performance measures in a multi-product closed-loop supply chain". Transportation Research Part E: Logistics and Transportation Review 47, n.º 4 (julio de 2011): 532–46. http://dx.doi.org/10.1016/j.tre.2010.12.001.

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Lejarza, Fernando y Michael Baldea. "Closed-loop optimal operational planning of supply chains with fast product quality dynamics". Computers & Chemical Engineering 132 (enero de 2020): 106594. http://dx.doi.org/10.1016/j.compchemeng.2019.106594.

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Aziza, Hassen, Christian Dufaza, Annie Perez y Said Hamdioui. "Configurable Operational Amplifier Architectures Based on Oxide Resistive RAMs". Journal of Circuits, Systems and Computers 28, n.º 13 (11 de enero de 2019): 1950216. http://dx.doi.org/10.1142/s0218126619502165.

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This paper introduces memristor-based operational amplifiers (OpAmps) in which semiconductor resistors are suppressed and replaced by memristors. The ability of the memristive elements to hold several resistance states is exploited to design programmable closed-loop OpAmps. An inverting OpAmp, an integrator and a differentiator are studied. Such designs are developed based on a calibrated memristor model, and offer dynamic configurability to realize different gains and corner frequencies at reduced chip area.

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Chen, Qian, Hanlin Sheng y Shengbin Jiang. "Integrated Physical Modeling and Optimal Control Method of Limited-Angle Torque Motor in Fuel Metering Apparatus". Micromachines 13, n.º 6 (15 de junio de 2022): 949. http://dx.doi.org/10.3390/mi13060949.

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Limited-angle torque motor (LATM) is a critical component to precisely drive the valve angle of an engine’s fuel metering apparatus and accurately measure the fuel flow, and research on it is of great significance. Thus, the LATM of a certain kind is regarded as the research object in this paper. Firstly, a Simscape-based LATM integrated physical modeling method is proposed, which can better demonstrate the real operational characteristics of a motor, compared with the current mathematical model. Secondly, a Proportional-Integral-Derivative (PID) parameter self-tuning method based on a constriction factor particle swarm optimization (CPSO) algorithm is broached since it is difficult to tune due to a large number of multi-loop cascade PID control parameters. Simulation and experimental results showed that the control performance increases by 40% in the triple closed-loop PID control system with a stronger disturbance rejection, simpler design, and quickly responds when compared with the previous empirical tuning method. The triple closed-loop PID control system comprises an angle loop + angle velocity loop + current loop and technically supports the engineering application design of motors.

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Hu, Zhilong, Kangyao Deng, Yi Cui, Xinxin Yang y Baochuan Zhang. "Steady-state and transient control strategies for a two-stage turbocharged diesel engine". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 232, n.º 9 (6 de octubre de 2017): 1167–79. http://dx.doi.org/10.1177/0954407017727442.

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Two-stage turbocharging technology is widely used to achieve higher engine power density and lower exhaust emissions. To solve a series of contradictions in matching, a regulated two-stage (RTS) turbocharging system is applied to reasonably control boost pressure. This paper investigated steady-state and transient control strategies for an RTS turbocharging system to achieve optimum fuel economy in steady-state conditions and better performance in transient conditions. The economic control strategies for steady-state operational conditions were based on an economic regulation law, which was established by a steady-state test of an engine with an RTS turbocharging system under all operating conditions. To optimize the transient performance, open-loop and closed-loop control systems (the latter with dynamic judgement) for the RTS system were designed and validated with experiments on a heavy-duty diesel engine. The experimental results demonstrated that the open-loop control strategy and the closed-loop strategy with dynamic judgement could improve the transient response performance. The optimum transient response performance was achieved by the closed-loop control system with dynamic judgement. Additionally, the combination of steady-state and transient control strategies could achieve the best fuel economy in steady-state conditions and good transient response performances.

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Fung, Vincent Wah Cheong y Kam Chuen Yung. "Developing Predictive Engineering Analytics to Formulate the Closed-Loop Management for Achieving Re-Industrialisation". International Journal of Software Science and Computational Intelligence 13, n.º 2 (abril de 2021): 1–22. http://dx.doi.org/10.4018/ijssci.2021040101.

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Regarding the process of printed circuit board assembly (PCBA), existing failure location methods are reactive in nature, while process parameters and performance cannot be predicted to achieve a high level of operational excellence. Designated PCB designs are not customized for specific manufacturing sites, while process performance becomes uncertain to clients and manufacturers. In this paper, an intelligent manufacturing performance predictive framework (IMPPF) is proposed in this paper, which structures the predictive engineering analytics for the smart manufacturing. First, the data collection from the PCBA process is structured by means of multi-responses Taguchi method, which guarantees the data reliability and quality. Second, the artificial neural network is adopted to learn from the existing operational data so as to provide the prediction on machine settings and process performance at the Gerber drawing stage. The contribution of this study is mainly to establish a closed-loop framework to facilitate the predictive engineering analytics for achieving re-industrialization.

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S. Sánchez, Allan G., Josué Soto-Vega, Esteban Tlelo-Cuautle y Martín Antonio Rodríguez-Licea. "Fractional-Order Approximation of PID Controller for Buck–Boost Converters". Micromachines 12, n.º 6 (21 de mayo de 2021): 591. http://dx.doi.org/10.3390/mi12060591.

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Viability of a fractional-order proportional–integral–derivative (PID) approximation to regulate voltage in buck–boost converters is investigated. The converter applications range not only to high-power ones but also in micro/nano-scale systems from biomedicine for energy management/harvesting. Using a classic closed-loop control diagram the controller effectiveness is determined. Fractional calculus is considered due to its ability at modeling different types of systems accurately. The non-integer approach is integrated into the control strategy through a Laplacian operator biquadratic approximation to generate a flat phase curve in the system closed-loop frequency response. The controller synthesis considers both robustness and closed-loop performance to ensure a fast and stable regulation characteristic. A simple tuning method provides the appropriate gains to meet design requirements. The superiority of proposed approach, determined by comparing the obtained time constants with those from typical PID controllers, confirms it as alternative to controller non-minimum phases systems. Experimental realization of the resulting controller, implemented through resistor–capacitor (RC) circuits and operational amplifiers (OPAMPs) in adder configuration, confirms its effectiveness and viability.

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Wang, Xun, Xiao Wen Zhang y Cheng Si Yang. "Experimental Analysis on Non-Dimensional Parameters of Closed-Loop Pulsating Heat Pipes". Advanced Materials Research 732-733 (agosto de 2013): 230–33. http://dx.doi.org/10.4028/www.scientific.net/amr.732-733.230.

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Based on experimental studies, this paper discusses the variation tendencies of three non-dimensional parameters including Ja, Bo and Pr which consist of various operational parameters and characteristic parameters, and then analyses their effects on heat transfer performance of closed-loop pulsating heat pipes (PHPs) at startup stage and steady operation stage. Results indicate that at startup stage, the values of Ja and Bo increase over time as a whole, while the values of Pr decrease; at steady operation stage, the values of three parameters all fluctuate within a narrow range. The results also show that heat transfer is due mainly to the exchange of latent heat under the experimental conditions.

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Aminzadeh, Hamed y Dalton Martini Colombo. "Analysis and Design Procedures of CMOS OTAs Based on Settling Time". Journal of Integrated Circuits and Systems 17, n.º 1 (30 de abril de 2022): 1–11. http://dx.doi.org/10.29292/jics.v17i1.590.

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Analysis of generic single-pole, two-pole, and three-pole operational transconductance amplifiers (OTAs) is carried out based on settling time. The most important design metrics of the open-loop frequency response, such as the stability margins and the gain-bandwidth product (GBW) are related to the settling time of single-, two- and three-stage OTAs in closed-loop configuration, enabling to present a design procedure for each OTA based on the settling time specifications. Transistor-level design examples are provided for each case to validate the described settling-based design strategies.

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Pan, Jianhua, J. Van de Vegte y J. K. Mills. "An Operational Method for Nonparametric Analysis of Feedback Control Systems". Journal of Dynamic Systems, Measurement, and Control 118, n.º 3 (1 de septiembre de 1996): 639–43. http://dx.doi.org/10.1115/1.2801195.

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An operational method of analysis using nonparametric impulse response models is proposed for the nonparametric analysis and design of feedback control systems. It is based on the algebra of convolution quotients, and represents common results such as closed-loop transfer functions in symbolic forms, which closely resemble those for conventional parametric analysis. In design applications, controllers are also expressed symbolically by means of convolution quotients. A deconvolution algorithm is proposed to compute the convolution quotients, and permits these symbolic forms to be evaluated and applied to nonparametric analysis and design.

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Cai, Zheng Ying, Ren Bin Xiao y Jia Heng Li. "A LCA Model for Cleaner Production Performance Measurement". Advanced Materials Research 599 (noviembre de 2012): 400–403. http://dx.doi.org/10.4028/www.scientific.net/amr.599.400.

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In cleaner production, all management processes of member enterprises come into being a closed-loop operation which needs integrated evaluation and effectively quantitative analysis tool. A Life Cycle model of cleaner production based on popular and practicable supply- chain operations reference model is built here, whose closed-loop framework structure and process decomposition ensure management performance of a multi-layered cleaner production system. Based on its performance system, operational performances are measurable and form an insightful conceptual framework that can be used to guide operation coordination in the whole life cycle of cleaner production. To measure and integrate performances including costs and benefits in different kinds of members, a Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) based on Vague set is employed. For application, a cleaner production case is simplified for illustration.

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31

Chen, Cheng-Po, Lucian Stoica, Emad Andarawis y Russell Simpson. "SOI Operational Amplifier Applications in 300°C Operating Environment". Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2017, HiTEN (1 de julio de 2017): 000109–12. http://dx.doi.org/10.4071/2380-4491.2017.hiten.109.

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Abstract A custom designed SOI operational amplifier (opamp) is used in two application circuits and characterized up to 300°C: 1. An instrumentation amplifier (in-amp) with a differential voltage gain of 100, and 2. A transimpedance amplifier (TIA) with a gain of 1.2 giga Ohm, used to sense picoamp level signals. The opamp operates with a 5-volt supply, and has rail-to-rail inputs and outputs. The open loop gain of the opamp is about 100 dB at room temperature and stays above 60 dB at 300°C. The in-amp uses the classic three operational amplifier (opamp) architecture with off-chip feedback resistors. The closed loop gain of the in-amp remains stable at 100, up to 250°C, and drops to 95 at 300°C. Temperature dwell test shows the in-amp maintaining stable functionality at 300°C for at least 1000 hours. The TIA also incorporates a silicon carbide diode to achieve gain compression by lowering the feedback gain when the input signal is higher, thus allowing a higher dynamic range input before the circuit output saturates.

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32

Ghadge, Abhijeet, Qifan Yang, Nigel Caldwell, Christian König y Manoj Kumar Tiwari. "Facility location for a closed-loop distribution network: a hybrid approach". International Journal of Retail & Distribution Management 44, n.º 9 (12 de septiembre de 2016): 884–902. http://dx.doi.org/10.1108/ijrdm-07-2015-0094.

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Purpose The purpose of this paper is to find a sustainable facility location solution for a closed-loop distribution network in the uncertain environment created by of high levels of product returns from online retailing coupled with growing pressure to reduce carbon emissions. Design/methodology/approach A case study approach attempts to optimize the distribution centre (DC) location decision for single and double hub scenarios. A hybrid approach combining centre of gravity and mixed integer programming is established for the un-capacitated multiple allocation facility location problem. Empirical data from a major national UK retail distributor network is used to validate the model. Findings The paper develops a contemporary model that can take into account multiple factors (e.g. operational and transportation costs and supply chain (SC) risks) while improving performance on environmental sustainability. Practical implications Based on varying product return rates, SC managers can decide whether to choose a single or a double hub solution to meet their needs. The study recommends a two hub facility location approach to mitigate emergent SC risks and disruptions. Originality/value A two-stage hybrid approach outlines a unique technique to generate candidate locations under twenty-first century conditions for new DCs.

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33

Huang, Lufei, Liwen Murong y Wencheng Wang. "Green closed-loop supply chain network design considering cost control and CO2 emission". Modern Supply Chain Research and Applications 2, n.º 1 (5 de febrero de 2020): 42–59. http://dx.doi.org/10.1108/mscra-02-2019-0005.

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PurposeEnvironmental issues have become an important concern in modern supply chain management. The structure of closed-loop supply chain (CLSC) networks, which considers both forward and reverse logistics, can greatly improve the utilization of materials and enhance the performance of the supply chain in coping with environmental impacts and cost control.Design/methodology/approachA biobjective mixed-integer programming model is developed to achieve the balance between environmental impact control and operational cost reduction. Various factors regarding the capacity level and the environmental level of facilities are incorporated in this study. The scenario-based method and the Epsilon method are employed to solve the stochastic programming model under uncertain demand.FindingsThe proposed stochastic mixed-integer programming (MIP) model is an effective way of formulating and solving the CLSC network design problem. The reliability and precision of the Epsilon method are verified based on the numerical experiments. Conversion efficiency calculation can achieve the trade-off between cost control and CO2 emissions. Managers should pay more attention to activities about facility operation. These nodes might be the main factors of costs and environmental impacts in the CLSC network. Both costs and CO2 emissions are influenced by return rate especially costs. Managers should be discreet in coping with cost control for CO2 emissions barely affected by return rate. It is advisable to convert the double target into a single target by the idea of “Efficiency of CO2 Emissions Control Reduction.” It can provide managers with a way to double-target conversion.Originality/valueWe proposed a biobjective optimization problem in the CLSC network considering environmental impact control and operational cost reduction. The scenario-based method and the Epsilon method are employed to solve the mixed-integer programming model under uncertain demand.

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Van Winsum, Wim y Wiebo Brouwer. "Time Headway in Car following and Operational Performance during Unexpected Braking". Perceptual and Motor Skills 84, n.º 3_suppl (junio de 1997): 1247–57. http://dx.doi.org/10.2466/pms.1997.84.3c.1247.

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The relation between car-following behaviour and braking performance was studied in a driving simulator. The theoretical perspective was that individual differences in tactical car-driving behaviour may be related to skills on the operational level of the driving task via a process of adaptation. In a sample of 16 young and middle-aged experienced drivers independent assessments were made of preferred time headway during car following and of braking skill. Starting from modern theories of visual-motor learning, braking performance was analyzed in terms of a reaction time component, an open-loop visual-motor component, and a closed-loop visual-motor component involving the precise adjustment of braking (timing and force) to the situation. The efficiency of the visual-motor component of braking was a strong and significant predictor of choice of time headway to the lead vehicle in such a way that less efficient braking indicated a preference for a longer time headway. This result supports the theory of adaptation on the individual level.

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Ramezani, Majid y Ali Mohammad Kimiagari. "Simultaneous optimization of operational and financial decisions to closed-loop supply chain network under uncertainty". Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 230, n.º 10 (8 de agosto de 2016): 1910–24. http://dx.doi.org/10.1177/0954405415578723.

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Patra, Sunandita, Malik Ghallab, Dana Nau y Paolo Traverso. "Acting and Planning Using Operational Models". Proceedings of the AAAI Conference on Artificial Intelligence 33 (17 de julio de 2019): 7691–98. http://dx.doi.org/10.1609/aaai.v33i01.33017691.

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The most common representation formalisms for planning are descriptive models. They abstractly describe what the actions do and are tailored for efficiently computing the next state(s) in a state transition system. But acting requires operational models that describe how to do things, with rich control structures for closed-loop online decision-making. Using descriptive representations for planning and operational representations for acting can lead to problems with developing and verifying consistency of the different models.We define and implement an integrated acting-and-planning system in which both planning and acting use the same operational models, which are written in a general-purpose hierarchical task-oriented language offering rich control structures. The acting component is inspired by the well-known PRS system, except that instead of being purely reactive, it can get advice from the planner. Our planning algorithm, RAEplan, plans by doing Monte Carlo rollout simulations of the actor’s operational models. Our experiments show significant benefits in the efficiency of the acting and planning system.

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Wang, Zhouyi, Jianding Yu y Yuanchao Lou. "Design of Double Closed Loop Control System for DC Motor Based on TX8C1010 Single Chip". Journal of Physics: Conference Series 2457, n.º 1 (1 de marzo de 2023): 012017. http://dx.doi.org/10.1088/1742-6596/2457/1/012017.

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Abstract In order to improve the operational strength and control precision of the DC motor, a double closed-loop control system based on TAIXIN TX8C1010 MCU is proposed. The single chip is based on a high-speed 8051 core, which is applied to home appliances and can realize the double closed-loop motor control algorithm. The given speed value provided by the potentiometer is compared with the real-time speed value and inputs the error to the speed loop function, which is based on the incremental PID algorithm, to calculate the reference current value. Then it is compared with the real-time current value and inputs the error into the current loop. The PWM signal duty cycle is determined by the output value of the current loop to adjust and stabilize the motor speed. The drive circuit outputs the PWM signal in the inverse amplification way to control the operation of the DC motor, and finally tests the function on the MAGTROL M-TEST7 motor test platform. The test results show that the control system has fast response speed, strong load capacity, good robustness and safety. Hence, TAIXIN TX8C1010 single-chip machine is feasible in the DC motor control. It can be improved to strengthen its load characteristics according to the parameters and applied to a variety of power DC motor control.

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Wu, Chun-Ho, Yung-Po Tsang, Carman Ka-Man Lee y Wai-Ki Ching. "A Blockchain-IoT Platform for the Smart Pallet Pooling Management". Sensors 21, n.º 18 (21 de septiembre de 2021): 6310. http://dx.doi.org/10.3390/s21186310.

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Pallet management as a backbone of logistics and supply chain activities is essential to supply chain parties, while a number of regulations, standards and operational constraints are considered in daily operations. In recent years, pallet pooling has been unconventionally advocated to manage pallets in a closed-loop system to enhance the sustainability and operational effectiveness, but pitfalls in terms of service reliability, quality compliance and pallet limitation when using a single service provider may occur. Therefore, this study incorporates a decentralisation mechanism into the pallet management to formulate a technological eco-system for pallet pooling, namely Pallet as a Service (PalletaaS), raised by the foundation of consortium blockchain and Internet of things (IoT). Consortium blockchain is regarded as the blockchain 3.0 to facilitate more industrial applications, except cryptocurrency, and the synergy of integrating a consortium blockchain and IoT is thus investigated. The corresponding layered architecture is proposed to structure the system deployment in the industry, in which the location-inventory-routing problem for pallet pooling is formulated. To demonstrate the values of this study, a case analysis to illustrate the human–computer interaction and pallet pooling operations is conducted. Overall, this study standardises the decentralised pallet management in the closed-loop mechanism, resulting in a constructive impact to sustainable development in the logistics industry.

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Hu, Cheng, Scarlett Chen y Zhe Wu. "Economic Model Predictive Control of Nonlinear Systems Using Online Learning of Neural Networks". Processes 11, n.º 2 (20 de enero de 2023): 342. http://dx.doi.org/10.3390/pr11020342.

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This work focuses on the development of a Lyapunov-based economic model predictive control (LEMPC) scheme that utilizes recurrent neural networks (RNNs) with an online update to optimize the economic benefits of switched non-linear systems subject to a prescribed switching schedule. We first develop an initial offline-learning RNN using historical operational data, and then update RNNs with real-time data to improve model prediction accuracy. The generalized error bounds for RNNs updated online with independent and identically distributed (i.i.d.) and non-i.i.d. data samples are derived, respectively. Subsequently, by incorporating online updating RNNs within LEMPC, probabilistic closed-loop stability, and economic optimality are achieved simultaneously for switched non-linear systems accounting for the RNN generalized error bound. A chemical process example with scheduled mode transitions is used to demonstrate that the closed-loop economic performance under LEMPC can be improved using an online update of RNNs.

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40

Li, Xiangyu, Jianping Hu y Xiaowei Liu. "Study of a closed-loop high-precision front-end circuit for tunneling magneto-resistance sensors". Modern Physics Letters B 33, n.º 08 (20 de marzo de 2019): 1950085. http://dx.doi.org/10.1142/s0217984919500854.

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A closed-loop high-precision front-end interface circuit in a standard 0.35 [Formula: see text]m CMOS technology for a tunneling magneto-resistance (TMR) sensor is presented in this paper. In consideration of processing a low frequency and weak geomagnetic signal, a low-noise front-end detection circuit is proposed with chopper technique to eliminate the 1/f noise and offset of operational amplifier. A novel ripple suppression loop is proposed for eliminating the ripple in a tunneling magneto-resistance sensor interface circuit. Even harmonics is eliminated by fully differential structure. The interface is fabricated in a standard 0.35 [Formula: see text]m CMOS process and the active circuit area is about [Formula: see text]. The interface chip consumes 7 mW at a 5 V supply and the 1/f noise corner frequency is lower than 1 Hz. The interface circuit of TMR sensors can achieve a better noise level of [Formula: see text]. The ripple can be suppressed to less than 10 [Formula: see text]V by ripple suppression loop.

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41

Wang, Yacan, Vincent Wiegerinck, Harold Krikke y Hongdan Zhang. "Understanding the purchase intention towards remanufactured product in closed-loop supply chains". International Journal of Physical Distribution & Logistics Management 43, n.º 10 (4 de noviembre de 2013): 866–88. http://dx.doi.org/10.1108/ijpdlm-01-2013-0011.

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Purpose – The paper aims to explore the reasons underlying the key assumption in the closed-loop supply chain (CLSC) literature that consumers' purchase intention is lower for remanufactured products than for new products. It aims to complement the predominantly operation-focused CLSC research by examining consumers' perception of and behavior relating to remanufactured products. Design/methodology/approach – A theoretical model is developed by integrating the concepts of perceived benefits and product knowledge with the theory of planned behavior and the theory of perceived risk. Then the model is examined through an empirical study in the Chinese automobile spare parts industry involving 288 respondents and using structural equation modeling. Findings – The results indicate that purchase intention is directly influenced by purchase attitude followed by perceived behavioral control and indirectly influenced by perceived risk, perceived benefit and product knowledge via attitude. Therefore, effective measures to promote consumers' purchase intention rely on coordinated policies built on multiple pillars instead of single factors. Originality/value – This is one of the first empirical studies to explore the factors that underpin consumers' purchase intention regarding remanufactured products. The results can be used to validate the key assumptions in operational models and foster new research in the context of CLSCs.

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42

Samadi, Masoud y Bahman Zarenezhad. "Experimental Study of a Closed Loop Pulsating Heat Pipe Aiming at Assessing the Optimized Operational Conditions". Periodica Polytechnica Mechanical Engineering 60, n.º 2 (2016): 96–102. http://dx.doi.org/10.3311/ppme.8703.

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Monazam, Esmail R., Ronald W. Breault y Lawrence J. Shadle. "Operational performance characteristics of an aerated L-valve operated within a closed circulating fluidized bed loop". Powder Technology 354 (septiembre de 2019): 82–91. http://dx.doi.org/10.1016/j.powtec.2019.05.044.

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Ritola, Ilkka, Harold Krikke y Marjolein C. J. Caniëls. "Learning from Returned Products in a Closed Loop Supply Chain: A Systematic Literature Review". Logistics 4, n.º 2 (8 de abril de 2020): 7. http://dx.doi.org/10.3390/logistics4020007.

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Product returns are a source of valuable information that can be used by firms and supply chains to improve products, services, and decision making. However, firms are struggling to maximize the value of this information, and the extant scholarly literature is scattered among various research streams. Using a systematic literature review, the state-of-the-art of product returns informational value research and limitations in the current body of work were examined and future directions for research suggested. Three types of informational value were identified, namely operational information, product related information, and customer-related information, along with four value-creating factors, namely strategic information system (IS) decisions, organizational learning, information sharing, and technological solutions. Implications for practitioners are discussed. Lastly, the limitations are discussed, along with recommendations and directions for future research work.

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Attia, Mohamed Sadok, Mohamed Karim Bouafoura y Naceur Benhadj Braiek. "Decentralized Suboptimal State Feedback Integral Tracking Control Design for Coupled Linear Time-Varying Systems". Mathematical Problems in Engineering 2020 (26 de julio de 2020): 1–10. http://dx.doi.org/10.1155/2020/7519014.

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In this paper, a suboptimal state feedback integral decentralized tracking control synthesis for interconnected linear time-variant systems is proposed by using orthogonal polynomials. Particularly, the use of operational matrices allows, by expanding the subsystem input states and outputs over a shifted Legendre polynomial basis, the conversion of time-varying parameter differential state equations to a set of time-independent algebraic ones. Hence, optimal open-loop state and control input coefficients are forwardly determined. These data are used to formulate a least-square problem, allowing the synthesis of decentralized state feedback integral control gains. Closed-loop asymptotic stability LMI conditions are given. The proposed approach effectiveness is proved by solving a nonconstant reference tracking problem for coupled inverted pendulums.

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46

Ran, Wenxue, Fan Chen, Qianni Wu y Sen Liu. "A Study of the Closed-Loop Supply Chain Coordination on Waste Glass Bottles Recycling". Mathematical Problems in Engineering 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/1049514.

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The recycling of waste products can sharply save manufacturing cost and improve the economic efficiency and corporate-reputation. It also has a great effect on the environment and resources protection. In the management of the closed-loop supply chain, the recycling of waste products and decision-making on pricing often directly affect the supply and demand of products and the operation efficiency of supply chain. Therefore, first we take waste glass bottles as an example and establish a mathematical model to solve the profit of manufacturers and retailers solely. Then, we analyzed whole supply chain profit under a dual-channel recycling condition which is directly recycled by consumers or by retailers. Finally, we concluded that no matter what product’s price, quality, profit, or operational efficiency of supply chain is, the overall recycling is better than the single node recycling model. Based on the analysis, we developed a new model to coordinate the profit of manufacturers and retailers in the supply chain with revenue-sharing contract. A numerical study shows that this approach is applicable and effective.

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Zhang, Yongming y Weida Chen. "Optimal operational and financing portfolio strategies for a capital-constrained closed-loop supply chain with supplier-remanufacturing". Computers & Industrial Engineering 168 (junio de 2022): 108133. http://dx.doi.org/10.1016/j.cie.2022.108133.

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48

Ataei, Mohammad, Rahmat-Allah Hooshmand y Moein Parastegari. "A Wide Range Robust PSS Design Based on Power System Pole-Placement Using Linear Matrix Inequality". Journal of Electrical Engineering 63, n.º 4 (1 de julio de 2012): 233–41. http://dx.doi.org/10.2478/v10187-012-0033-7.

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A Wide Range Robust PSS Design Based on Power System Pole-Placement Using Linear Matrix InequalityIn this paper, a new method for robust PSS design based on the power system pole placement is presented. In this stabilizer, a feedback gain matrix is used as a controller. The controller design is proposed by formulating the problem of robust stability in a Linear Matrix Inequality (LMI) form. Then, the feedback gain matrix is designed based on the desired region of the closed loop system poles. This stabilizer shifts the poles of the power system in different operational points into the desired regions ins-plane, such that the response of the power system will have proper damping ratio in all the operational points. The uncertainties of the power system parameters are also considered in this robust technique. Finally, in order to show the advantages of the proposed method in comparison with conventional PSS, some simulation results are provided for a power system case study in different operational points.

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49

Dsouza, Ajwal, Gordon W. Price, Mike Dixon y Thomas Graham. "A Conceptual Framework for Incorporation of Composting in Closed-Loop Urban Controlled Environment Agriculture". Sustainability 13, n.º 5 (25 de febrero de 2021): 2471. http://dx.doi.org/10.3390/su13052471.

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Controlled environment agriculture (CEA), specifically advanced greenhouses, plant factories, and vertical farms, has a significant role to play in the urban agri-food landscape through provision of fresh and nutritious food for urban populations. With the push towards improving sustainability of these systems, a circular or closed-loop approach for managing resources is desirable. These crop production systems generate biowaste in the form of crop and growing substrate residues, the disposal of which not only impacts the immediate environment, but also represents a loss of valuable resources. Closing the resource loop through composting of crop residues and urban biowaste is presented. Composting allows for the recovery of carbon dioxide and plant nutrients that can be reused as inputs for crop production, while also providing a mechanism for managing and valorizing biowastes. A conceptual framework for integrating carbon dioxide and nutrient recovery through composting in a CEA system is described along with potential environmental benefits over conventional inputs. Challenges involved in the recovery and reuse of each component, as well as possible solutions, are discussed. Supplementary technologies such as biofiltration, bioponics, ozonation, and electrochemical oxidation are presented as means to overcome some operational challenges. Gaps in research are identified and future research directions are proposed.

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50

Dutta, Saikat, Tim Harrison, Christopher Patrick Ward, Roger Dixon y Tara Scott. "A new approach to railway track switch actuation: Dynamic simulation and control of a self-adjusting switch". Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 234, n.º 7 (27 de agosto de 2019): 779–90. http://dx.doi.org/10.1177/0954409719868129.

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The track switch is one of the key assets in any railway network. It is essential to allow trains to change route; however, when it fails, significant delays are almost inevitable. A relatively common fault is ‘loss of detection’, which can happen when there is a gradual track movement and the switch machines (actuators) no longer close the gap between the switch rail and stock rail to within safe tolerance levels. Currently, such misalignment is mitigated by a preventative programme of inspection and manual re-adjustment. In contrast to many other industries, the actuators are exclusively operated in open loop, with sensors (often limit switches) mainly being used for detection. Hence, an opportunity exists to investigate the closed loop control concepts for improving the operation of the switch. This paper proposes two advances: first, a novel approach is taken for modelling the dynamic performance of track switch actuators and the moving permanent-way components of the switch. The model is validated against real data from an operational switch. Secondly, the resulting dynamic model is then used to examine the implementation of closed loop feedback control as an integral part of track switch actuation. The proposed controller is found to perform well and offers the potential of ‘self-adjustment’, i.e. re-adjusting itself to close any gap (within a predefined range) between the stock and switch rails, thereby completing the switching operation.

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