scholarly journals Studies Regarding the Use of Pneumatic Muscles in Precise Positioning Systems

2021 ◽  
Vol 11 (21) ◽  
pp. 9855
Author(s):  
Ioana Mădălina Petre
Keyword(s):  
High Performance ◽  
Position Control ◽  
Pressure Control ◽  
Pneumatic Muscle ◽  
Positioning Systems ◽  
Pneumatic Muscles ◽  
Contraction Ratio ◽  
Input Pressure ◽  
Important Challenge ◽  
The Relationship

The paper presents the methods and results of an experimental study that highlights the behavior of a pneumatic actuator under different pressures and with different loads applied. One important challenge that occurs in the application of pneumatic muscles is the phenomenon of hysteresis, which causes a nonlinear relationship between the input–output values. The aim of this study is to identify the occurrence of hysteresis in the operation of a small pneumatic muscle in different conditions. Thus, different loads are attached to the free end of a pneumatic muscle and different successive pressures are applied in order to examine the hysteresis of the contraction ratio when the muscle is inflated and then deflated. The obtained equations that describe the relationship between the input pressure and the axial contraction are significant for reaching a high-performance position control. In this regard, the article proposes a solution to increase positioning accuracy based on pressure control using a proportional pressure regulator and a programmable logic controller.

ELASTOMERIC NANOPARTICLES: EFFECTIVE ADDITIVE FOR HIGH PERFORMANCE RUBBER NANOCOMPOSITES

2020 ◽  
pp. 000-000 ◽  
Author(s):  
Xiang Wang ◽  
Jinliang Qiao ◽  
Zhifeng Zhou ◽  
Jianming Gao ◽  
Guicun Qi ◽  
...  
Keyword(s):  
Automobile Industry ◽  
High Performance ◽  
Rolling Resistance ◽  
Skid Resistance ◽  
Rubber Composites ◽  
Wear Life ◽  
Important Challenge ◽  
The Relationship ◽  
Wet Skid Resistance

ABSTRACT The “magic triangle” is the most important challenge to rubber composites for the automobile industry. According to the magic triangle, it is difficult to improve the rolling resistance (energy saving), wet skid resistance (safety), and wear (life) of a tire simultaneously. However, ∼5% decrease of rolling resistance, >20% increase of wet skid resistance, and 15% decrease of wear were achieved after adding a small amount of elastomeric nanoparticle (ENP). The effect of ENP on the performances of rubber composites was expounded by characterization of the dispersion of filler and the relationship between filler and rubber. The main difference between ENPs and other nanoparticles was that ENPs acted as not only a part of filler but also as a part of rubber in rubber composites.

scholarly journals Experimental Research on the Hysteretic Behaviour of Pressurized Artificial Muscles Made from Elastomers with Aramid Fibre Insertions

Actuators ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 83
Author(s):  
Ovidiu Filip ◽  
Andrea Deaconescu ◽  
Tudor Deaconescu
Keyword(s):  
Experimental Research ◽  
High Performance ◽  
Hysteresis Loops ◽  
Artificial Muscles ◽  
Degree Polynomial ◽  
Pneumatic Muscle ◽  
Positioning Systems ◽  
Hysteretic Behaviour ◽  
Aramid Fibres ◽  
Hysteresis Behaviour

Inherent hysteresis behaviour of pressurized artificial muscles is complicated to understand and handle, calling for experimental research that allows the modelling of this phenomenon. The paper presents the results of the experimental study of the hysteretic behaviour of a small-size pneumatic muscle. The specific hysteresis loops were revealed by isotonic and isometric tests. Starting from hypothesis according to that the tube used for the pneumatic muscle is made entirely of aramid fibres enveloped by an elastomer material that merely ensures their airtightness, the paper presents the hysteresis curves that describe the radial and axial dimensional modifications as well as the variation of the developed forces for different feed pressures. The obtained third-degree polynomial equations underlie the configuration of high-performance positioning systems.

Position Control of PWM-Actuated Pneumatic Muscle Actuator System

2011 ◽  
Author(s):  
Ville Jouppila ◽  
Asko Ellman
Keyword(s):  
Position Control ◽  
System Model ◽  
Modeling Error ◽  
Stick Slip ◽  
Pneumatic Muscle ◽  
Positioning Systems ◽  
Highly Nonlinear ◽  
Pneumatic Muscle Actuator ◽  
Non Linear System ◽  
Real Challenge

Pneumatic servo positioning systems have been in use for long time and subject to wide spectrum of studies due to their numerous advantages: inexpensive, clean, safe and high ratio of power to weight. However, the compressibility of air and the inherent non-linearity of these systems continue to make achieving accurate position control a real challenge. Conventional pneumatic servo systems are based on cylinder actuators that are difficult to control precisely due to the aforementioned nonlinearities as well as the nonlinear behavior of the air flow through the valve, the friction between the cylinder and the piston, and the stick slip effect at the low velocity of the system. In this paper, a position servo control system using a pneumatic muscle actuator is studied. Pneumatic muscle actuator is a novel type of actuator which has even higher force to weight ratio than the cylinder. In addition, muscle actuator introduces a stick slip free operation giving an interesting option for positioning systems. However, significant hysteresis and position dependant force result in a highly nonlinear system, a real challenge for good control performance. In this paper, pneumatic muscle actuator is controlled by a low-cost on/off valve with PWM-strategy instead of costly servo or proportional valve. The main processes of the system, including flow dynamics, pressure dynamics, force dynamics and load dynamics are derived to provide a full nonlinear model that captures all the major nonlinearities of the system. This model is used for analyzing and tuning the controller performances by simulations before implementing in the real system. In addition, a recently introduced method of using bipolynomial functions to model the valve flow rate is utilized to provide a continuous and invertible description of flow for controller designs. A proportional plus velocity plus acceleration controller with feed-forward component (PVA+FF) is designed based on the linearized system model. For a comparison, a sliding mode controller (SMC) based on linear as well as non-linear system model are designed. The performance of the designed controllers is studied by simulations. The stability and performance analysis includes the effects of friction modeling error and valve modeling error. The robustness of the controllers is tested by varying the payload mass of the system.

About the concept of synthesis of high-performance detection and positioning systems in the areas of elements falling, separated from strategic and space missiles on the trajectories of their flight during tests and regular operation

2018 ◽  
pp. 10-21
Author(s):  
G. G. Vokin
Keyword(s):  
High Performance ◽  
Physical Nature ◽  
Positioning Systems ◽  
Physical Conditions ◽  
Highly Efficient

The article describes the approach and topical issues of synthesis of highly efficient transportable systems for search and determination of coordinates in the areas of elements falling, separated from the missiles, taking into account the dislocation of pre-empted areas of fall and physical conditions in their territories. The principles of these systems are based on the rational integration of traditional and non-traditional information sensors of different physical nature, which record the moments of landing of separated parts of the missiles.

scholarly journals A Time-Based Objective Measure of Exposure to the Food Environment

2019 ◽  
Vol 16 (7) ◽  
pp. 1180 ◽  
Author(s):  
Jason Scully ◽  
Anne Moudon ◽  
Philip Hurvitz ◽  
Anju Aggarwal ◽  
Adam Drewnowski
Keyword(s):  
Food Environment ◽  
Fast Food ◽  
Objective Measure ◽  
Mobility Patterns ◽  
Time Duration ◽  
Positioning Systems ◽  
Global Positioning ◽  
Fast Food Restaurants ◽  
Logistic Regressions ◽  
The Relationship

Exposure to food environments has mainly been limited to counting food outlets near participants’ homes. This study considers food environment exposures in time and space using global positioning systems (GPS) records and fast food restaurants (FFRs) as the environment of interest. Data came from 412 participants (median participant age of 45) in the Seattle Obesity Study II who completed a survey, wore GPS receivers, and filled out travel logs for seven days. FFR locations were obtained from Public Health Seattle King County and geocoded. Exposure was conceptualized as contact between stressors (FFRs) and receptors (participants’ mobility records from GPS data) using four proximities: 21 m, 100 m, 500 m, and ½ mile. Measures included count of proximal FFRs, time duration in proximity to ≥1 FFR, and time duration in proximity to FFRs weighted by FFR counts. Self-reported exposures (FFR visits) were excluded from these measures. Logistic regressions tested associations between one or more reported FFR visits and the three exposure measures at the four proximities. Time spent in proximity to an FFR was associated with significantly higher odds of FFR visits at all proximities. Weighted duration also showed positive associations with FFR visits at 21-m and 100-m proximities. FFR counts were not associated with FFR visits. Duration of exposure helps measure the relationship between the food environment, mobility patterns, and health behaviors. The stronger associations between exposure and outcome found at closer proximities (<100 m) need further research.

scholarly journals The Relationship between Learning Styles and Academic Performance: Consistency among Multiple Assessment Methods in Psychology and Education Students

2021 ◽  
Vol 13 (6) ◽  
pp. 3341
Author(s):  
Jesús Maya ◽  
Juan F. Luesia ◽  
Javier Pérez-Padilla
Keyword(s):  
Early Childhood ◽  
Academic Performance ◽  
Learning Styles ◽  
Primary Education ◽  
High Performance ◽  
Multiple Choice ◽  
Assessment Methods ◽  
Theory And Practice ◽  
Education Students ◽  
The Relationship

Universities strive to ensure quality education focused on the diversity of the student body. According to experiential learning theory, students display different learning preferences. This study has a three-fold objective: to compare learning styles based on personal and educational variables, to analyze the association between learning styles, the level of academic performance, and consistency of performance in four assessment methods, and to examine the influence of learning dimensions in students with medium-high performance in the assessment methods. An interdisciplinary approach was designed involving 289 psychology, early childhood education and primary education students at two universities in Spain. The Learning Style Inventory was used to assess learning styles and dimensions. The assessment methods used in the developmental psychology course included the following question formats: multiple-choice, short answer, creation-elaboration and an elaboration question on the relationship between theory and practice. Univariate analysis, multivariate analysis, and binomial logistic models were computed. The results reveal Psychology students to be more assimilative (theoretical and abstract), while early childhood and primary education students were evenly distributed among styles and were more divergent and convergent (practical) in absolute terms. In addition, high scores in perception (abstract conceptualization) were associated with a high level of performance on the multiple-choice tests and the elaboration question on the relationship between theory and practice. Abstract conceptualization was also associated with medium-high performance in all assessment methods and this variable predicted consistent high performance, independent of the assessment method. This study highlights the importance of promoting abstract conceptualization. Recommendations for enhancing this learning dimension are presented.

scholarly journals Relationship between Plasma Trimethylamine N-Oxide Levels and Renal Dysfunction in Patients with Hypertension

2021 ◽  
pp. 1-12
Author(s):  
Jia Zhou ◽  
Dingkun Wang ◽  
Bingong Li ◽  
Xuelian Li ◽  
Xingjun Lai ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Kidney Disease ◽  
Renal Dysfunction ◽  
High Performance ◽  
Characteristic Curve ◽  
Area Under The Curve ◽  
Hypertensive Patients ◽  
Ckd Stage ◽  
Liquid Chromatography Tandem Mass ◽  
The Relationship

<b><i>Introduction:</i></b> Trimethylamine N-oxide (TMAO) is a metabolite produced by gut bacteria. Although increased TMAO levels have been linked to hypertension (HTN) and chronic kidney disease (CKD) with poor prognosis, no clinical studies have directly addressed the relationship between them. In this study, we investigated the relationship between TMAO and renal dysfunction in hypertensive patients. <b><i>Methods:</i></b> We included healthy controls (<i>n</i> = 50), hypertensive patients (<i>n</i> = 46), and hypertensive patients with renal dysfunction (<i>n</i> = 143). Their blood pressure values were taken as the highest measured blood pressure. Renal function was evaluated using the estimated glomerular filtration rate. Plasma TMAO levels were measured using high-performance liquid chromatography tandem mass spectrometry. <b><i>Results:</i></b> We found significant differences in plasma TMAO levels among the 3 groups (<i>p</i> &#x3c; 0.01). The plasma TMAO of patients with HTN was significantly higher than that of healthy people, and the plasma TMAO of patients with HTN complicated by renal dysfunction was significantly higher than either of the other groups. Patients in the highest TMAO quartile were at a higher risk of developing CKD stage 5 than those in the lowest quartile. In the receiver operating characteristic curve, the area under the curve of TMAO combined with β 2-macroglobulin for predicting renal dysfunction in patients with HTN was 0.85 (95% confidence interval 0.80–0.90). <b><i>Conclusion:</i></b> An elevated TMAO level reflects higher levels of HTN and more severe renal dysfunction. TMAO, combined with β 2-macroglobulin levels, may assist in diagnosing CKD in hypertensive patients. Plasma TMAO has predictive value for early kidney disease in hypertensive patients.

scholarly journals Changes in Optical Properties upon Dye–Clay Interaction: Experimental Evaluation and Applications

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 197
Author(s):  
Giorgia Giovannini ◽  
René M. Rossi ◽  
Luciano F. Boesel
Keyword(s):  
Optical Properties ◽  
Hybrid Materials ◽  
High Performance ◽  
Fluorescent Properties ◽  
Chemical Mechanisms ◽  
Strong Electrostatic Interaction ◽  
Potential Applications ◽  
Photochemical Properties ◽  
Physical And Chemical ◽  
The Relationship

The development of hybrid materials with unique optical properties has been a challenge for the creation of high-performance composites. The improved photophysical and photochemical properties observed when fluorophores interact with clay minerals, as well as the accessibility and easy handling of such natural materials, make these nanocomposites attractive for designing novel optical hybrid materials. Here, we present a method of promoting this interaction by conjugating dyes with chitosan. The fluorescent properties of conjugated dye–montmorillonite (MMT) hybrids were similar to those of free dye–MMT hybrids. Moreover, we analyzed the relationship between the changes in optical properties of the dye interacting with clay and its structure and defined the physical and chemical mechanisms that take place upon dye–MMT interactions leading to the optical changes. Conjugation to chitosan additionally ensures stable adsorption on clay nanoplatelets due to the strong electrostatic interaction between chitosan and clay. This work thus provides a method to facilitate the design of solid-state hybrid nanomaterials relevant for potential applications in bioimaging, sensing and optical purposes.

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