Considering Link Flexibility in the Dynamic Synthesis of Closed-Loop Mechanisms: A General Approach

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
A. M. Shafei ◽  
H. R. Shafei
Keyword(s):  
Lagrange Multipliers ◽  
Closed Loop ◽  
Motion Equations ◽  
Modal Expansion ◽  
Flexible Links ◽  
Dynamic Synthesis ◽  
Expansion Technique ◽  
Impulsive Constraints ◽  
Link Flexibility ◽  
The Impact

Abstract This paper has focused on the dynamic analysis of mechanisms with closed-loop configuration while considering the flexibility of links. In order to present a general formulation for such a closed-loop mechanism, it is allowed to have any arbitrary number of flexible links in its chain-like structure. The truncated assumed modal expansion technique has been used here to model link flexibility. Moreover, due to the closed nature of the mentioned mechanism, which imposes finite holonomic constraints on the system, the appearance of Lagrange multipliers in the dynamic motion equations obtained by Lagrangian formulation is unavoidable. So, the Gibbs-Appell (G-A) formulation has been applied to get rid of these Lagrange multipliers and to ease the extraction of governing motion equations. In addition to the finite constraints, the impulsive constraints, which originate from the collision of system joints with the ground, have also been formulated here using the Newton's kinematic impact law. Finally, to stress the generality of the proposed formulation in deriving and solving the motion equations of complex closed-loop mechanisms in both the impact and non-impact conditions, the computer simulation results for a mechanism with four flexible links and closed-loop configuration have been presented.

The Impact of Visual Feedback Type on the Mastery of Visuo-Motor Transformations

2012 ◽  
Vol 220 (1) ◽  
pp. 3-9 ◽  
Author(s):  
Sandra Sülzenbrück
Keyword(s):  
Empirical Research ◽  
Visual Feedback ◽  
Closed Loop ◽  
Motor Planning ◽  
Visual Input ◽  
Closed Loop Control ◽  
Loop Control ◽  
Feedback Type ◽  
Effective Use ◽  
The Impact

For the effective use of modern tools, the inherent visuo-motor transformation needs to be mastered. The successful adjustment to and learning of these transformations crucially depends on practice conditions, particularly on the type of visual feedback during practice. Here, a review about empirical research exploring the influence of continuous and terminal visual feedback during practice on the mastery of visuo-motor transformations is provided. Two studies investigating the impact of the type of visual feedback on either direction-dependent visuo-motor gains or the complex visuo-motor transformation of a virtual two-sided lever are presented in more detail. The findings of these studies indicate that the continuous availability of visual feedback supports performance when closed-loop control is possible, but impairs performance when visual input is no longer available. Different approaches to explain these performance differences due to the type of visual feedback during practice are considered. For example, these differences could reflect a process of re-optimization of motor planning in a novel environment or represent effects of the specificity of practice. Furthermore, differences in the allocation of attention during movements with terminal and continuous visual feedback could account for the observed differences.

scholarly journals Research on Closed-Loop Supply Chain Decision-Making in Different Cooperation Modes with Government’s Reward-Penalty Mechanism

2021 ◽  
Vol 13 (11) ◽  
pp. 6425
Author(s):  
Quanxi Li ◽  
Haowei Zhang ◽  
Kailing Liu
Keyword(s):  
Supply Chain ◽  
Closed Loop ◽  
Stackelberg Game ◽  
Recycling Rate ◽  
Transfer Payment ◽  
Closed Loop Supply Chain ◽  
Asymmetry Of Information ◽  
Optimal Decisions ◽  
The Government ◽  
The Impact

In closed-loop supply chains (CLSC), manufacturers, retailers, and recyclers perform their duties. Due to the asymmetry of information among enterprises, it is difficult for them to maximize efficiency and profits. To maximize the efficiency and profit of the CLSC, this study establishes five cooperation models of CLSC under the government‘s reward–penalty mechanism. We make decisions on wholesale prices, retail prices, transfer payment prices, and recovery rates relying on the Stackelberg game method and compare the optimal decisions. This paper analyzes the impact of the government reward-penalty mechanism on optimal decisions and how members in CLSC choose partners. We find that the government’s reward-penalty mechanism can effectively increase the recycling rate of used products and the total profit of the closed-loop supply chain. According to the calculation results of the models, under the government’s reward-penalty mechanism, the cooperation can improve the CLSC’s used products recycling capacity and profitability. In a supply chain, the more members participate in the cooperation, the higher profit the CLSC obtain. However, the cooperation mode of all members may lead to monopoly, which is not approved by government and customers.

scholarly journals Partial Energy Transfer Model of Lamb Waves Scattering in Materially Isotropic Waveguides

2021 ◽  
Vol 11 (10) ◽  
pp. 4508
Author(s):  
Pavel Šofer ◽  
Michal Šofer ◽  
Marek Raček ◽  
Dawid Cekus ◽  
Paweł Kwiatoń
Keyword(s):  
Energy Transfer ◽  
Lamb Waves ◽  
Hybrid Approach ◽  
Wave Mode ◽  
Transfer Model ◽  
Material Interface ◽  
Modal Expansion ◽  
Scattering Coefficients ◽  
Expansion Technique ◽  
Partial Energy

The scattering phenomena of the fundamental antisymmetric Lamb wave mode with a horizontal notch enabling the partial energy transfer (PET) option is addressed in this paper. The PET functionality for a given waveguide is realized using the material interface. The energy scattering coefficients are identified using two methods, namely, a hybrid approach, which utilizes the finite element method (FEM) and the general orthogonality relation, and the semi-analytical approach, which combines the modal expansion technique with the orthogonal property of Lamb waves. Using the stress and displacement continuity conditions on the present (sub)waveguide interfaces, one can explicitly derive the global scattering matrix, which allows detailed analysis of the scattering process across the considered interfaces. Both methods are then adopted on a simple representation of a surface breaking crack in the form of a vertical notch, of which a certain section enables not only the reflection of the incident energy, but also its nonzero transfer. The presented results show very good conformity between both utilized approaches, thus leading to further development of an alternative technique.

Accelerating Large-Format Metal Additive Manufacturing: How Controls R&D Is Driving Speed, Scale, and Efficiency

2020 ◽  
Author(s):  
Brian T. Gibson ◽  
Paritosh Mhatre ◽  
Michael C. Borish ◽  
Justin L. West ◽  
Emma D. Betters ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Large Scale ◽  
Closed Loop ◽  
Size Control ◽  
Pool Size ◽  
Large Format ◽  
Layer Height ◽  
Melt Pool ◽  
The Impact ◽  
Melt Pool Size

Abstract This article highlights work at Oak Ridge National Laboratory’s Manufacturing Demonstration Facility to develop closed-loop, feedback control for laser-wire based Directed Energy Deposition, a form of metal Big Area Additive Manufacturing (m-BAAM), a process being developed in partnership with GKN Aerospace specifically for the production of Ti-6Al-4V pre-forms for aerospace components. A large-scale structural demonstrator component is presented as a case-study in which not just control, but the entire 3D printing workflow for m-BAAM is discussed in detail, including design principles for large-format metal AM, toolpath generation, parameter development, process control, and system operation, as well as post-print net-shape geometric analysis and finish machining. In terms of control, a multi-sensor approach has been utilized to measure both layer height and melt pool size, and multiple modes of closed-loop control have been developed to manipulate process parameters (laser power, print speed, deposition rate) to control these variables. Layer height control and melt pool size control have yielded excellent local (intralayer) and global (component-level) geometry control, and the impact of melt pool size control in particular on thermal gradients and material properties is the subject of continuing research. Further, these modes of control have allowed the process to advance to higher deposition rates (exceeding 7.5 lb/hr), larger parts (1-meter scale), shorter build times, and higher overall efficiency. The control modes are examined individually, highlighting their development, demonstration, and lessons learned, and it is shown how they operate concurrently to enable the printing of a large-scale, near net shape Ti-6Al-4V component.

scholarly journals Contribution of Nanotechnology and Nanomaterials to the Treatment of Diabetic Patients by Aid of Novel Inventions

2020 ◽  
pp. 29-40
Author(s):  
Shiva Najigivi ◽  
Seyedahmadreza Mirmotallebi ◽  
Alireza Najigivi
Keyword(s):  
Diabetes Mellitus ◽  
Drug Delivery ◽  
Human Health ◽  
Carbon Nanostructures ◽  
Closed Loop ◽  
Insulin Injection ◽  
Diabetic Patients ◽  
Temporal Response ◽  
Nanoscience And Nanotechnology ◽  
The Impact

Nanoscience and Nanotechnology are highly growing their significance in diabetic supplies and research nowadays. It is an area that included nanomaterials, nanosensors and nanostructures as well as nanoparticle projects and also their usage in human health research. Particularly, nanotechnology helps to the production of diabetic supplies, materials together with the development of novel glucose and insulin injection devices as well as their measurement sensors by the aid of nanomaterials. These materials mostly could be metal nanoparticles together with carbon nanostructures by nano dimension delivery mechanisms modalities which hold the potential to vividly recover the excellence of life of diabetic patients. Nanoscience and nanotechnology in diabetic research have facilitated and provided more truthful data for identifying diabetes mellitus. It is also worth mentioning that the nanotechnology could highly enhance the impact of drug delivery by addition of nanoscale materials and increase the glucose feeling, temporal response as well as glucose nursing. Furthermore, it is proposing novel nanoscale methods named closed-loop insulin delivery approaches which mechanically release insulin drug in reply to fluctuating blood glucose heights. Besides, the mixture of nanotechnology by medication has shaped a novel field of nanomedicine which could enhance human health level. It is worthwhile to mention that some of the applications of nanotechnology for the treatment of diabetic patients can be the production of diabetic supplies by nanotechnology. One of the most important diabetic instruments that could highly relieve the life of patients these days could be nano diabetic shoes which will describe here. In this research, applications of nanoscience and nanotechnology in treating diabetic patients were discussed.

scholarly journals Hybrid Closed-Loop System Achieves Optimal Perioperative Glycemia in a Boy With Type 1 Diabetes: A Case Report

2021 ◽  
Vol 9 ◽  
Author(s):  
Jesus Dominguez-Riscart ◽  
Nuria Buero-Fernandez ◽  
Ana Garcia-Zarzuela ◽  
Fernando A. Marmolejo-Franco ◽  
Ana C. Perez-Guerrero ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Blood Glucose ◽  
Insulin Infusion ◽  
Closed Loop ◽  
Total Duration ◽  
Blood Glucose Monitoring ◽  
Medical Team ◽  
The Family ◽  
The Impact

The goal in type 1 diabetes (T1D) therapy is to maintain optimal glycemic control under any circumstance. Diabetes technology is in continuous development to achieve this goal. The most advanced Food and Drug Administration- and European Medicines Agency-approved devices are hybrid closed-loop (HCL) systems, which deliver insulin subcutaneously in response to glucose levels according to an automated algorithm. T1D is frequently encountered in the perioperative period. The latest international guidelines for the management of children with diabetes undergoing surgery include specific adjustments to the patient's insulin therapy, hourly blood glucose monitoring, and intravenous (IV) insulin infusion. However, these guidelines were published while the HCL systems were still marginal. We present a case of a 9-year-old boy with long-standing T1D, under HCL system therapy for the last 9 months, and needing surgery for an appendectomy. We agreed with the family, the surgical team, and the anesthesiologists to continue HCL insulin infusion, without further adjustments, hourly blood glucose checks or IV insulin, while monitoring closely. The HCL system was able to keep glycemia within range for the total duration of the overnight fast, the surgery, and the initial recovery, without any external intervention or correction bolus. This is, to the best of our knowledge, the first reported pediatric case to undergo major surgery using a HCL system, and the results were absolutely satisfactory for the patient, his family, and the medical team. We believe that technology is ripe enough to advocate for a “take your pump to surgery” message, minimizing the impact and our interventions. The medical team may discuss this possibility with the family and patients.

scholarly journals Monitor-Watcher Use, Nurses’ Knowledge of Electrocardiographic Monitoring, and Arrhythmia Detection

2021 ◽  
Vol 30 (1) ◽  
pp. 38-44
Author(s):  
Marjorie Funk ◽  
Kristopher P. Fennie ◽  
Krista A. Knudson ◽  
Halley Ruppel
Keyword(s):  
Intensive Care Unit ◽  
Closed Loop ◽  
Test Accuracy ◽  
Ecg Monitoring ◽  
Knowledge Test ◽  
Arrhythmia Detection ◽  
Electrocardiographic Monitoring ◽  
Online Test ◽  
The Impact ◽  
Nurses Knowledge

Background Electrocardiographic telemetry monitors are ubiquitous in hospitals. Dedicated monitor watchers, either on the unit or in a centralized location, are often responsible for observing telemetry monitors and responding to their alarms. The impact of use of monitor watchers is not known. Objectives To evaluate the association of monitor-watcher use with (1) nurses’ knowledge of electrocardiographic (ECG) monitoring and (2) accuracy of arrhythmia detection. Methods Baseline data from 37 non–intensive care unit cardiac patient care areas in 17 hospitals in the Practical Use of the Latest Standards for Electrocardiography trial were analyzed. Nurses’ knowledge (n = 1136 nurses) was measured using a validated, 20-item online test. Accuracy of arrhythmia detection (n = 1189 patients) was assessed for 5 consecutive days by comparing arrhythmias stored in the monitor with nurses’ documentation. Multiple regression was used to evaluate the association of use of monitor watchers with scores on the ECG-monitoring knowledge test. The association of monitor-watcher use with accuracy of arrhythmia detection was examined by χ2 analysis. Results Of the 37 units, 13 (35%) had monitor watchers. Use of monitor watchers was not independently associated with ECG-monitoring knowledge (P = .08). The presence of monitor watchers also was not significantly associated with the accuracy of arrhythmia detection (P = .94). Conclusion Although the use of monitor watchers was not associated with diminished nurses’ knowledge of ECG monitoring, it also was not associated with more accurate arrhythmia detection. If implementing a monitor-watcher program, critical safety points, such as ensuring closed-loop communication, must be considered.

scholarly journals Examining the optimal timing for closed-loop auditory stimulation of slow-wave sleep in young and older adults

SLEEP ◽  
2019 ◽  
Vol 43 (6) ◽  
Author(s):  
Miguel Navarrete ◽  
Jules Schneider ◽  
Hong-Viet V Ngo ◽  
Mario Valderrama ◽  
Alexander J Casson ◽  
...  
Keyword(s):  
Slow Wave ◽  
Closed Loop ◽  
Slow Wave Sleep ◽  
Auditory Stimulation ◽  
Optimal Time ◽  
Optimal Timing ◽  
Experimental Conditions ◽  
Young Subjects ◽  
The Impact ◽  
Specific Phase

Abstract Study Objectives Closed-loop auditory stimulation (CLAS) is a method for enhancing slow oscillations (SOs) through the presentation of auditory clicks during sleep. CLAS boosts SOs amplitude and sleep spindle power, but the optimal timing for click delivery remains unclear. Here, we determine the optimal time to present auditory clicks to maximize the enhancement of SO amplitude and spindle likelihood. Methods We examined the main factors predicting SO amplitude and sleep spindles in a dataset of 21 young and 17 older subjects. The participants received CLAS during slow-wave-sleep in two experimental conditions: sham and auditory stimulation. Post-stimulus SOs and spindles were evaluated according to the click phase on the SOs and compared between and within conditions. Results We revealed that auditory clicks applied anywhere on the positive portion of the SO increased SO amplitudes and spindle likelihood, although the interval of opportunity was shorter in the older group. For both groups, analyses showed that the optimal timing for click delivery is close to the SO peak phase. Click phase on the SO wave was the main factor determining the impact of auditory stimulation on spindle likelihood for young subjects, whereas for older participants, the temporal lag since the last spindle was a better predictor of spindle likelihood. Conclusions Our data suggest that CLAS can more effectively boost SOs during specific phase windows, and these differ between young and older participants. It is possible that this is due to the fluctuation of sensory inputs modulated by the thalamocortical networks during the SO.

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