scholarly journals VIBRATION FREQUENCY DENSITY CONTROL METHOD IN VIBRATION CONDITIONS

2019 ◽  
pp. 41-47
Author(s):  
O. Yu. Oliinyk
Keyword(s):  
Vibration Frequency ◽  
Vibrational Frequency ◽  
Control Method ◽  
Experimental Studies ◽  
Approximation Error ◽  
Frequency Characteristics ◽  
Organic Glass ◽  
Experimental Methodology ◽  
Measuring Instruments ◽  
Density Control

The use of existing vibration frequency measuring instruments for monitoring technological parameters inside apparatus and equipment is limited due to the presence of vibrations and industrial noise. The lack of data on the use of part of the technological apparatus as flow resonators through the unexplored basic analytical equations for determining the amplitude-frequency characteristics of such resonators determined the direction of these studies. The article is devoted to studies aimed at establishing the relationship between the vibrational field of the resonator, which is used as part of the technological apparatus with a controlled environment, and its reaction in the form of a change in the frequency or amplitude of the resonator’s own vibrations, which carries information about the properties of the substance in the apparatus. The experimental setup diagram, experimental methodology, and data on determining the oscillation frequency of the resonator under vibration conditions for metallic (corrosion-resistant steel) and non-metallic (organic glass) resonators are presented. The curves obtained from the experimental values were approximated using linear and hyperbolic approximations. It was found that the use of hyperbolic approximation reduces the average approximation error by more than six times. It was found that the error of the hyperbolic approximation error does not exceed 0.022% for a metal resonator and 0.05% for an organic glass resonator. The conducted experimental studies confirm the presence of a determinate coupling of the measured frequency characteristics of the resonator with the density, which was measured inside the equipment. The obtained data was used to develop the scientific and methodological foundations of the vibrational frequency control method in conditions of vibration using a part of the device as a resonator of the vibrational frequency sensor.

scholarly journals The Influence of Genetics in Myopia Control: A Pilot Study

2021 ◽  
Vol 10 (4) ◽  
pp. 808
Author(s):  
Cristina Alvarez-Peregrina ◽  
Miguel Ángel Sánchez-Tena ◽  
Clara Martinez-Perez ◽  
Catalina Santiago-Dorrego ◽  
Thomas Yvert ◽  
...  
Keyword(s):  
Pilot Study ◽  
Treatment Response ◽  
Axial Length ◽  
Contact Lenses ◽  
Control Method ◽  
Saliva Sample ◽  
Experimental Studies ◽  
Strong Linkage Disequilibrium ◽  
Student’S T ◽  
Myopia Control

Background: Many epidemiological and experimental studies have established that myopia is caused by a complex interaction between common genetic and environmental factors. The objective of this study was to describe and compare the allelic and genotypic frequencies of the rs524952 (GJD2), rs8000973 (ZIC2), rs1881492 (CHRNG), rs1656404 (PRSS56), rs235770 (BMP2), and rs7744813 (KCNQ5) SNPs (single-nucleotide polymorphism) between responder and nonresponder patients who had undergone a two-year treatment with lenses for myopia control. Method: Twenty-eight participants from the MiSight Assessment Study Spain (MASS), who had received treatment for myopia control for two years with MiSight contact lenses, were examined. The criteria for better/worse treatment response was the change in the axial length (< / ≥ 0.22 mm two years after the treatment). The clinical procedure consisted of the extraction of a saliva sample, and the participants also underwent an optometric examination. Genetic data were analyzed using SNPStats software (Catalan Institute of Oncology, Barcelona, Spain), and statistical analysis was performed using SPSS v.25 (SPSS Inc., Chicago, IL, USA). Demographic variables were analyzed using the Student’s t-test. Results: The T allele, the one with the lowest frequency, of the “rs235770” SNP was associated with a better treatment response [AL/CR (axial length/corneal radius): OR = 3.37; CI = 1.079–10.886; SE (spherical equivalent): OR = 1.26; CI: = 0.519–57.169; p = 0.019). By performing haplotype analysis, significant differences were found between the rs235770…rs1881492 and rs235770–rs1656404 polymorphisms. The latter presented a strong linkage disequilibrium with each other (r2 ≥ 0.54). Conclusion: The result of lens therapies for myopia control could vary depending on genetic variants. Studies with a larger sample are needed to confirm the results presented in this pilot study.

scholarly journals Thermal Inertia Characterization of Multilayer Lightweight Walls: Numerical Analysis and Experimental Validation

2021 ◽  
Vol 11 (11) ◽  
pp. 5008
Author(s):  
Juan José del Coz-Díaz ◽  
Felipe Pedro Álvarez-Rabanal ◽  
Mar Alonso-Martínez ◽  
Juan Enrique Martínez-Martínez
Keyword(s):  
Lightweight Concrete ◽  
Thermal Flux ◽  
Experimental Studies ◽  
Thermal Inertia ◽  
Transient State ◽  
Experimental Tests ◽  
Building Design ◽  
Experimental Methodology ◽  
Improve Energy Efficiency ◽  
Concrete Blocks

The thermal inertia properties of construction elements have gained a great deal of importance in building design over the last few years. Many investigations have shown that this is the key factor to improve energy efficiency and obtain optimal comfort conditions in buildings. However, experimental tests are expensive and time consuming and the development of new products requires shorter analysis times. In this sense, the goal of this research is to analyze the thermal behavior of a wall made up of lightweight concrete blocks covered with layers of insulating materials in steady- and transient-state conditions. For this, numerical and experimental studies were done, taking outdoor temperature and relative humidity as a function of time into account. Furthermore, multi-criteria optimization based on the design of the experimental methodology is used to minimize errors in thermal material properties and to understand the main parameters that influence the numerical simulation of thermal inertia. Numerical Finite Element Models (FEM) will take conduction, convection and radiation phenomena in the recesses of lightweight concrete blocks into account, as well as the film conditions established in the UNE-EN ISO 6946 standard. Finally, the numerical ISO-13786 standard and the experimental results are compared in terms of wall thermal transmittance, thermal flux, and temperature evolution, as well as the dynamic thermal inertia parameters, showing a good agreement in some cases, allowing builders, architects, and engineers to develop new construction elements in a short time with the new proposed methodology.

scholarly journals Extended-State-Observer-Based Super Twisting Control for Pneumatic Muscle Actuators

Actuators ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 35
Author(s):  
Yu Cao ◽  
Zhongzheng Fu ◽  
Mengshi Zhang ◽  
Jian Huang
Keyword(s):  
Control Method ◽  
Experimental Studies ◽  
State Observer ◽  
Extended State Observer ◽  
Extended State ◽  
Pneumatic Muscle ◽  
System States ◽  
The Stability ◽  
Twisting Control ◽  
Muscle Actuators

This paper presents a tracking control method for pneumatic muscle actuators (PMAs). Considering that the PMA platform only feedbacks position, and the velocity and disturbances cannot be observed directly, we use the extended-state-observer (ESO) for simultaneously estimating the system states and disturbances by using measurable variables. Integrated with the ESO, a super twisting controller (STC) is design based on estimated states to realize the high-precision tracking. According to the Lyapunov theorem, the stability of the closed-loop system is ensured. Simulation and experimental studies are conducted, and the results show the convergence of the ESO and the effectiveness of the proposed method.

EXPERIMENTAL STUDIES ON THE DEVELOPMENT OF AN AUTOMATED SYSTEM FOR REGULATING THE SOIL DENSITY USED IN A SEEDING MACHINE

2021 ◽  
pp. 9-15
Author(s):  
ALEKSEI S. DOROKHOV ◽  
Keyword(s):  
Control System ◽  
Automatic Control ◽  
Automatic Control System ◽  
Power Supply ◽  
Experimental Studies ◽  
Automated System ◽  
Statistical Characteristics ◽  
Vegetable Crops ◽  
Soil Density ◽  
Density Control

Research on the development of an automatic control system for the rolling-in working units is aimed at establishing the reliability and analytical relationships, determining the quality indicators of work in real conditions of the rolling-in working units of a seeding machine, and checking the patterns obtained in the fi eld and identifi ed theoretically. Research on the development of an automatic control system for the rolling implements was carried out when sowing dragee seeds of table beet of the Bordeaux variety with a seeding unit consisting of a Belarus-4235 tractor and a Monopil S15/12 precision seeding machine. The system for automatic control of soil density includes the main hardware and software: actuators for maintaining and deepening the rolling working units, microcontrollers, motor drivers, a non-contact ultrasonic sensor, a power supply unit and a sensor for measuring soil density. The paper presents the results of a study to determine the soil density when sowing seeds of table beet, depending on the moisture content of the soil in the sowing layer. The authors describe research methodology, provide graphical relationships between changes in soil density and the depth of seeding, and comment on the main obtained statistical characteristics of the experiment. As a result of the study, structural, echnological and functional diagrams of a rolling rink with an automatic control system using electronically controlled electric cylinders (linear actuators) have been developed. The optimal parameters of the linear drive of the press roller have been established: power - 50W, power supply - 12V, rod stroke - 200…600 mm, speed - 10…45 mm/s, load - 200…900 N. Experimental studies have shown the applicability of the presented system of the automatic control of soil density, which ensures the optimum density of the seedbed of 1.3…1.4 g/cm³. The described technique can be used to develop a soil density control system when sowing seeds of other vegetable crops.

Effect of Blade Aspiration Slot Configuration on the Aerodynamic Performance of a Highly Loaded Aspirated Compressor Cascade

2017 ◽  
Author(s):  
Longxin Zhang ◽  
Le Cai ◽  
Bao Liu ◽  
Jun Ding ◽  
Songtao Wang
Keyword(s):  
Flow Control ◽  
Flow Rate ◽  
Control Method ◽  
Active Flow Control ◽  
Experimental Studies ◽  
Aerodynamic Performance ◽  
Flow Path ◽  
Compressor Cascade ◽  
Flow Loss ◽  
Highly Loaded

As a promising active flow control method, boundary layer suction (BLS) can be used to enhance the aerodynamic performance of the highly-loaded compressor effectively, and due to this reason, extensive studies have been carried out on it. However, contrast to those abundant studies focusing on the flow control effects of BLS, little attention has been paid on the design method of the aspiration flow path. This work presents a 3-D steady numerical simulation on a highly-loaded aspirated compressor cascade. The aspiration slot is implemented at its best location based on the previous experimental studies and the aspiration flow rate is fix to 1.5% of the inlet massflow. The plenum configuration follows the blade shape and remains unchanged. One-side-aspiration manner is adopted to simplify the aspiration devices. Two critical geometry parameters, slot angle and slot width, are varied to study the effects of blade aspiration slot configuration on the cascade loss, radial distribution of the aspiration flow rate and inner flow structures within the aspiration flow path. Results show that the slot configuration does affect the cascade performance. In comparison with the throughflow performance, it is especially true once the flow loss caused by the aspiration flow path is also taken into account, and higher flow loss will be generated within the aspiration flow path if an inappropriate scheme is adopted. In the present investigation, apart from the cases with larger negative slot angle, a wider slot is more preferable to a narrower one, since it could enhance the aspiration capacity near the endwall regions and lower the dissipation loss within the aspiration flow path. In terms of the slot angle, a larger negative value, i.e., the slot direction more aligned with the incoming flow, is not beneficial to improve the throughflow performance, while concerning the flow loss yield by the aspiration flow path, a proper negative slot angle is always optimal.

scholarly journals Research the hardness of polymer materials after turning

2020 ◽  
Vol 329 ◽  
pp. 03041
Author(s):  
Oleg Erenkov ◽  
Elena Yavorskaya
Keyword(s):  
Experimental Studies ◽  
Polymer Materials ◽  
Experimental Methodology ◽  
Elastic Aftereffect

The paper presents the results of experimental studies to determine the hardness of the treated surface depending on the conditions and machining type of workpieces made of textolite, caprolon and fluoroplastic. The experimental methodology and explanation of the reasons for changing the hardness of the treated surface for the investigated variants of machining the materials are under study. The results of studying the influence of the phenomenon of elastic aftereffect of the polymer materials after workpieces machining are obtained.

Balancing Control of a Mobile Manipulator with Two Wheels by an Acceleration-Based Disturbance Observer

2018 ◽  
Vol 15 (03) ◽  
pp. 1850005 ◽  
Author(s):  
Yeong-Geol Bae ◽  
Seul Jung
Keyword(s):  
Disturbance Observer ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Experimental Studies ◽  
Service Robot ◽  
Mobile Manipulator ◽  
Control Performance ◽  
Six Degrees Of Freedom ◽  
Inertia Model ◽  
Balancing Control

This paper presents the balancing control performance of a mobile manipulator built in the laboratory as a service robot called Korean robot worker (KOBOKER). The robot is designed and implemented with two wheels as a mobile base and two arms with six degrees-of-freedom each. Kinematics and dynamics of the robot are analyzed. For the balancing control performance, two wheels are controlled independently by the time-delayed control method based on the inertia model of the robot. The acceleration information obtained directly from the sensor is used for the modified disturbance observer structure called an acceleration-based disturbance observer (AbDOB). Experimental studies of the balancing control of the robot are conducted to compare the control performances by both a PID control method and an AbDOB.

scholarly journals The influence of a country’s brands and industry on its image

2020 ◽  
Vol 55 (1) ◽  
pp. 27-62
Author(s):  
Carmen Lopez ◽  
George Balabanis
Keyword(s):  
Experimental Studies ◽  
Place Branding ◽  
Product Category ◽  
Schema Theory ◽  
Experimental Methodology ◽  
Cross Sectional ◽  
Economic Dimension ◽  
Content Type ◽  
The Uk

Purpose Extant research has largely treated country image (CI) as an exogenous variable, focusing mostly on its consequences for consumers’ evaluations and purchases of products or brands originating from a country. Scant research has examined the instrumental role of a country’s brands and products in the evaluations of CI. This study aims to investigate how the brands of a country contribute to CI ratings and the conditions underlying their effect on CI. Design/methodology/approach Three experimental studies test the hypotheses, one pertaining to the effect of brands on CI (N = 227), the second to the effect of products on CI (N = 116) and the third to the effect of brands and products on industry image (N = 215). The experimental approach overcomes the limitations of cross-sectional surveys commonly used in CI studies to detect the direction of the observed effects. Furthermore, respondents (British consumers) were allowed to determine the brands and products associated with a country. Findings Drawing on memory schema theory, across three studies, the authors identify two types of reverse inferences: from brand to CI and from product category to CI. The reverse inference from a brand to a superordinate image is stronger for industry image than for CI. Research limitations/implications This research focuses on consumers’ evaluations from only one country (the UK). Further research could replicate the studies across different countries and with different countries of origin (COOs). Researchers could also examine the influence of brands misidentified with the wrong COO and mistakenly stored as such in consumers’ memories. Practical implications The results are relevant for managers and consultants working with country- (place-) branding campaigns. Brands and industries can help strengthen the evaluations of the economic dimension of different countries; however, these assets are underdeveloped in country-branding campaigns. Linking countries with brands and industries in campaigns could result in positive associations, which, in turn, could enhance the reputational rating of the countries. Originality/value This research extends previous studies on the effects of a country’s products and brands on CI by incorporating the mediating role of industry image between brands/products and CI, separating the effects of brand and product category on CI, allowing consumers to determine, which brands and products are associated with a country and adopting an experimental methodology to ascertain the causal direction of the effects.

scholarly journals Low-Cost Position Sensorless Speed Control of PMSM Drive Using Four-Switch Inverter

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 741 ◽  
Author(s):  
Omer Kivanc ◽  
Salih Ozturk
Keyword(s):  
Control Method ◽  
Low Cost ◽  
Experimental Studies ◽  
Speed Control ◽  
Estimation Algorithm ◽  
Phase Lock Loop ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Current Controller ◽  
Position Sensorless

A low-cost position sensorless speed control method for permanent magnet synchronous motors (PMSMs) is proposed using a space vector PWM based four-switch three-phase (FSTP) inverter. The stator feedforward d q -axes voltages are obtained for the position sensorless PMSM drive. The q-axis current controller output with a first order low-pass filter formulates the rotor speed estimation algorithm in a closed-loop fashion similar to PLL (Phase Lock Loop) and the output of the d-axis current controller acts as the derivative representation in the stator feedforward voltage equation. The proposed method is quite insensitive to multiple simultaneous parameter variations such as rotor flux linkage and stator resistance due to the dynamic effects of the PI current regulator outputs that are used in the stator feedforward voltages with a proper value of K gain in the q-axis stator voltage equation. The feasibility and effectiveness of the proposed position sensorless speed control scheme for the PMSM drive using an FSTP inverter are verified by simulation and experimental studies.

scholarly journals Adaptive PD Control Based on RBF Neural Network for a Wire-Driven Parallel Robot and Prototype Experiments

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Yuqi Wang ◽  
Qi Lin ◽  
Xiaoguang Wang ◽  
Fangui Zhou
Keyword(s):  
Neural Network ◽  
Adaptive Control ◽  
Control Method ◽  
Rbf Neural Network ◽  
Approximation Error ◽  
Wind Tunnel Test ◽  
Parallel Robot ◽  
Network Control ◽  
Pd Control ◽  
Control Scheme

An adaptive PD control scheme is proposed for the support system of a wire-driven parallel robot (WDPR) used in a wind tunnel test. The control scheme combines a PD control and an adaptive control based on a radial basis function (RBF) neural network. The PD control is used to track the trajectory of the end effector of the WDPR. The experimental environment, the external disturbances, and other factors result in uncertainties of some parameters for the WDPR; therefore, the RBF neural network control method is used to approximate the parameters. An adaptive control algorithm is developed to reduce the approximation error and improve the robustness and control precision of the WDPR. It is demonstrated that the closed-loop system is stable based on the Lyapunov stability theory. The simulation results show that the proposed control scheme results in a good performance of the WDPR. The experimental results of the prototype experiments show that the WDPR operates on the desired trajectory; the proposed control method is correct and effective, and the experimental error is small and meets the requirements.

Sign in / Sign up

Export Citation Format

Share Document