scholarly journals Evaluation of the Thermofluidic Performance of Climatic Chambers: Numerical and Experimental Studies

Fluids ◽  
2021 ◽  
Vol 6 (12) ◽  
pp. 433
Author(s):  
Bahareh Ramezani ◽  
António Tadeu ◽  
Tiago Jesus ◽  
Michael Brett ◽  
Joel Mendes
Keyword(s):  
Experimental Studies ◽  
Industrial Applications ◽  
Controlled Environment ◽  
Thermal Loss ◽  
Climatic Chamber ◽  
Ansys Fluent ◽  
Flow Heat ◽  
Computational Fluid Dynamics Cfd ◽  
The Relationship ◽  
Industrial Demand

Climatic chambers are highly important in research and industrial applications and are used to examine manufactured samples, specimens, or components in controlled environment conditions. Despite the growing industrial demand for climatic chambers, only a few published studies have specifically concentrated on performance analysis and functional improvements through numerical and experimental studies. In this study, a 3D computational fluid dynamics (CFD) model of a climatic chamber was developed using Ansys Fluent to simulate the fluid flow, heat, and mass transfer to obtain the velocity, temperature, and relative humidity fields in the interior box of a 1200 L climatic chamber. The results were then validated with experimental data from a prototype. Finally, the heat losses of the surrounding components of the chamber were calculated, and the relationship between the inside temperature and the overall thermal loss was modelled. This validated numerical model provides the possibility of optimising the performance of climate chambers by reducing the thermal loss from the walls and modifying the air flow pattern inside the chamber.

scholarly journals Magnetic pulse processing of strawberries in the climatic chamber

2021 ◽  
Vol 247 ◽  
pp. 01038
Author(s):  
Dmitriy Khort ◽  
Alexey Kutyrev ◽  
Rostislav Filippov ◽  
Stepan Semichev
Keyword(s):  
Pulse Repetition Frequency ◽  
Experimental Studies ◽  
Low Frequency ◽  
High Sensitivity ◽  
Pulse Field ◽  
Physical Factors ◽  
Magnetic Pulse ◽  
Climatic Chamber ◽  
Energy Factors ◽  
The Relationship

The article presents the results of experimental studies on the magnetic pulse treatment of strawberries in a climatic chamber. The analysis of the obtained data showed that the greatest effect from the treatment of plants with a low-frequency magnetic pulse field in the phase of peduncle formation was obtained on plants that were treated with a magnetic induction equal to 4 MT, a pulse repetition frequency of 32 Hz and a duty cycle of 20. The relationship between the parameters of low-frequency magnetic pulse radiation and the photosynthetic activity of the leaf apparatus at various stages of ontogenesis, and the qualitative composition of fruits at the stage of maturation is revealed. The high sensitivity of plant organisms to the effects of energy factors, the parameters of which differ in exposure and physical factors, is shown. At the same time, the nature of the response of plants is complex, ambiguous and is determined not only by the electrophysical parameters of the electric field, but also by the specific, varietal and technological features of the crop.

Development of Pipe Flow Generators

2011 ◽  
Vol 233-235 ◽  
pp. 2432-2438
Author(s):  
Song Hao Wang ◽  
Ronald José Doblado Perez ◽  
Ronald García ◽  
Jia Cheng Chen
Keyword(s):  
Rapid Prototyping ◽  
Pipe Flow ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Rotor Design ◽  
Modern Engineering ◽  
Different Types ◽  
Computational Fluid Dynamics Cfd ◽  
Turbine Design ◽  
The Relationship

This study aims to research and develop Pipe Flow Generators. The focus in this paper is on the rotor design for pipes of different sizes. Modern engineering tools such as Computational Fluid Dynamics (CFD) software and Rapid Prototyping technology are utilized to facilitate the numerical and experimental studies. The CFD numerical simulations consist of two and three-dimensional transient and steady analyses. These simulations were conducted to find the relationship between the flow rate, blade geometry and number of blades. During the experimentation process, Rapid Prototyping Technology (RP) was used to fabricate many different types of turbine geometries to test different impeller parameters. RPM and voltages where measured for each turbine design. The study leads to several important findings for better pipe flow generators design.

scholarly journals CFD Analysis of a solar flat plate collector with different cross sections

Enfoque UTE ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 95-108 ◽  
Author(s):  
Anthony Xavier Andrade Cando ◽  
William Quitiaquez Sarzosa ◽  
Luis Fernando Toapanta
Keyword(s):  
Flat Plate ◽  
Cross Section ◽  
Cross Sections ◽  
Industrial Applications ◽  
Type I ◽  
Solar Thermal Energy ◽  
Ansys Fluent ◽  
Fluid Behavior ◽  
Computational Fluid Dynamics Cfd ◽  
Flat Plate Collector

Low and medium solar heating systems used for domestic and industrial applications, such as water and space heating, usually utilize solar flat plate collectors in order to absorb solar thermal energy converting it into heat and then transferring the heat to a fluid (usually water or air) that flows through it. The aim of this study is to evaluate the solar flat plate collector’s efficiency and the fluid behavior inside the pipeline with three different cross sections, whose hydraulic diameters are 10, 5.12 and 6.16 mm, by using ANSYS Fluent. The results obtained from the Computational Fluid Dynamics (CFD) tool showed that the collector with the Type I cross section reached temperatures up to 330 K at the pipe outlet obtaining an efficiency of 68 %, higher than those of Types II and III, whose efficiencies were 51 % and 60 %, respectively. Type I cross section also presented the lowest values in both speed and pressure drop, these being 0.266 m/s and 108.3 Pa, respectively.

Potential Role of Inflammation in Associations between Particulate Matter and Heart Failure

2018 ◽  
Vol 24 (3) ◽  
pp. 341-358 ◽  
Author(s):  
Xiaotong Ji ◽  
Yingying Zhang ◽  
Guangke Li ◽  
Nan Sang
Keyword(s):  
Heart Failure ◽  
Particulate Matter ◽  
Inflammatory Response ◽  
Heart Diseases ◽  
Experimental Studies ◽  
Epidemiological Studies ◽  
Inflammatory Mechanism ◽  
High Concentrations ◽  
Future Work ◽  
The Relationship

Recently, numerous studies have found that particulate matter (PM) exposure is correlated with increased hospitalization and mortality from heart failure (HF). In addition to problems with circulation, HF patients often display high expression of cytokines in the failing heart. Thus, as a recurring heart problem, HF is thought to be a disorder characterized in part by the inflammatory response. In this review, we intend to discuss the relationship between PM exposure and HF that is based on inflammatory mechanism and to provide a comprehensive, updated evaluation of the related studies. Epidemiological studies on PM-induced heart diseases are focused on high concentrations of PM, high pollutant load exposure in winter, or susceptible groups with heart diseases, etc. Furthermore, it appears that the relationship between fine or ultrafine PM and HF is stronger than that between HF and coarse PM. However, fewer studies paid attention to PM components. As for experimental studies, it is worth noting that coarse PM may indirectly promote the inflammatory response in the heart through systematic circulation of cytokines produced primarily in the lungs, while ultrafine PM and its components can enter circulation and further induce inflammation directly in the heart. In terms of PM exposure and enhanced inflammation during the pathogenesis of HF, this article reviews the following mechanisms: hemodynamics, oxidative stress, Toll-like receptors (TLRs) and epigenetic regulation. However, many problems are still unsolved, and future work will be needed to clarify the complex biologic mechanisms and to identify the specific components of PM responsible for adverse effects on heart health.

scholarly journals Experimental studies on the transformation from firn to ice in the wet-snow zone of temperate glaciers

1997 ◽  
Vol 24 ◽  
pp. 181-185 ◽  
Author(s):  
Katsuhisa Kawashima ◽  
Tomomi Yamada
Keyword(s):  
Experimental Studies ◽  
Ice Formation ◽  
Compression Tests ◽  
Densification Rate ◽  
Overburden Pressure ◽  
Proportionality Constant ◽  
Wet Snow ◽  
Water Saturated ◽  
The Relationship ◽  
Good Agreement

The densification of water-saturated firn, which had formed just above the firn-ice transition in the wet-snow zone of temperate glaciers, was investigated by compression tests under pressures ranging from 0.036 to 0.173 MPa, with special reference to the relationship between densification rate, time and pressure. At each test, the logarithm of the densification rate was proportional to the logarithm of the time, and its proportionality constant increased exponentially with increasing pressure. The time necessary for ice formation in the firn aquifer was calculated using the empirical formula obtained from the tests. Consequently, the necessary time decreased exponentially as the pressure increased, which shows that the transformation from firn in ice can be completed within the period when the firn aquifer exists, if the overburden pressure acting on the water-saturated firn is above 0.12–0.14 MPa. This critical value of pressure was in good agreement with the overburden pressure obtained from depth–density curves of temperate glaciers. It was concluded that the depth of firn–ice transition was self-balanced by the overburden pressure to result in the concentration between 20 and 30 m.

scholarly journals Application of intelligent orienteering based on Internet of things

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Donghui Zhang ◽  
Ruijie Liu
Keyword(s):  
Internet Of Things ◽  
Network Architecture ◽  
Emergency Services ◽  
Simulation Experiment ◽  
Experimental Studies ◽  
Signal Stability ◽  
Anchor Nodes ◽  
Set Up ◽  
The Relationship ◽  
The Internet Of Things

Abstract Orienteering has gradually changed from a professional sport to a civilian sport. Especially in recent years, orienteering has been widely popularized. Many colleges and universities in China have also set up this course. With the improvement of people’s living conditions, orienteering has really become a leisure sport in modern people’s life. The reduced difficulty of sports enables more people to participate, but it also exposes a series of problems. As the existing positioning technology is relatively backward, the progress in personnel tracking, emergency services, and other aspects is slow. To solve these problems, a new intelligent orienteering application system is developed based on the Internet of things. ZigBee network architecture is adopted in the system. ZigBee is the mainstream scheme in the current wireless sensor network technology, which has many advantages such as convenient carrying, low power consumption, and signal stability. Due to the complex communication environment in mobile signal, the collected information is processed by signal amplification and signal anti-interference technology. By adding anti-interference devices, video isolators and other devices, the signal is guaranteed to the maximum extent. In order to verify the actual effect of this system, through a number of experimental studies including the relationship between error and traffic radius and the relationship between coverage and the number of anchor nodes, the data shows that the scheme studied in this paper has a greater improvement in comprehensive performance than the traditional scheme, significantly improving the accuracy and coverage. Especially the coverage is close to 100% in the simulation experiment. This research has achieved good results and can be widely used in orienteering training and competition.

scholarly journals Deep Convolutional Neural Network with RNNs for Complex Activity Recognition Using Wrist-Worn Wearable Sensor Data

Electronics ◽  
2021 ◽  
Vol 10 (14) ◽  
pp. 1685
Author(s):  
Sakorn Mekruksavanich ◽  
Anuchit Jitpattanakul
Keyword(s):  
Neural Networks ◽  
Activity Recognition ◽  
Human Activities ◽  
Recognition Performance ◽  
Confusion Matrix ◽  
Experimental Studies ◽  
Industrial Applications ◽  
Sensor Data ◽  
Complex Activity ◽  
Activity Data

Sensor-based human activity recognition (S-HAR) has become an important and high-impact topic of research within human-centered computing. In the last decade, successful applications of S-HAR have been presented through fruitful academic research and industrial applications, including for healthcare monitoring, smart home controlling, and daily sport tracking. However, the growing requirements of many current applications for recognizing complex human activities (CHA) have begun to attract the attention of the HAR research field when compared with simple human activities (SHA). S-HAR has shown that deep learning (DL), a type of machine learning based on complicated artificial neural networks, has a significant degree of recognition efficiency. Convolutional neural networks (CNNs) and recurrent neural networks (RNNs) are two different types of DL methods that have been successfully applied to the S-HAR challenge in recent years. In this paper, we focused on four RNN-based DL models (LSTMs, BiLSTMs, GRUs, and BiGRUs) that performed complex activity recognition tasks. The efficiency of four hybrid DL models that combine convolutional layers with the efficient RNN-based models was also studied. Experimental studies on the UTwente dataset demonstrated that the suggested hybrid RNN-based models achieved a high level of recognition performance along with a variety of performance indicators, including accuracy, F1-score, and confusion matrix. The experimental results show that the hybrid DL model called CNN-BiGRU outperformed the other DL models with a high accuracy of 98.89% when using only complex activity data. Moreover, the CNN-BiGRU model also achieved the highest recognition performance in other scenarios (99.44% by using only simple activity data and 98.78% with a combination of simple and complex activities).

scholarly journals Experimental and CFD Simulations of the Aerosol Flow in the Air Ventilating the Underground Excavation in Terms of SARS-CoV-2 Transmission

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4743
Author(s):  
Tomasz Janoszek ◽  
Zbigniew Lubosik ◽  
Lucjan Świerczek ◽  
Andrzej Walentek ◽  
Jerzy Jaroszewicz
Keyword(s):  
Numerical Calculations ◽  
Mining Institute ◽  
Ventilation Network ◽  
Underground Excavation ◽  
In Situ Tests ◽  
Ansys Fluent ◽  
Aerosol Emission ◽  
Ansys Cfx ◽  
Computational Fluid Dynamics Cfd

The paper presents the results of experimental and model tests of transport of dispersed fluid droplets forming a cloud of aerosol in a stream of air ventilating a selected section of the underground excavation. The excavation selected for testing is part of the ventilation network of the Experimental Mine Barbara of the Central Mining Institute. For given environmental conditions, such as temperature, pressure, relative humidity, and velocity of air, the distribution of aerosol droplet changes in the mixture of air and water vapor along the excavation at a distance was measured at 10 m, 25 m, and 50 m from the source of its emission. The source of aerosol emission in the excavation space was a water nozzle that was located 25 m from the inlet (inlet) of the excavation. The obtained results of in situ tests were related to the results of numerical calculations using computational fluid dynamics (CFD). Numerical calculations were performed using Ansys-Fluent and Ansys-CFX software. The dimensions and geometry of the excavation under investigation are presented. The authors describe the adopted assumptions and conditions for the numerical model and discuss the results of the numerical solution.

Analysis of Late Phase Severe Accident Phenomena in CANDU Plant

2017 ◽  
Vol 3 (2) ◽  
Author(s):  
D. Dupleac
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Late Phase ◽  
Severe Accident ◽  
Ansys Fluent ◽  
Water Depletion ◽  
Sources Of Uncertainty ◽  
Parametric Studies ◽  
Computational Fluid Dynamics Cfd ◽  
Containment Pressure

The paper overviews the analytical studies performed at Politehnica University of Bucharest on the analysis of late phase severe accident phenomena in a Canada Deuterium Uranium (CANDU) plant. The calculations start from a dry debris bed at the bottom of calandria vessel. Both SCDAPSIM/RELAP code and ansys-fluent computational fluid dynamics (CFD) code are used. Parametric studies are performed in order to quantify the effect of several identified sources of uncertainty on calandria vessel failure: metallic fraction of zirconium inside the debris, containment pressure, timing of water depletion inside calandria vessel, steam circulation in calandria vessel above debris bed, debris temperature at moment of water depletion inside calandria vessel, calandria vault nodalization, and the gap heat transfer coefficient.

Relation between understanding and agreeing in response to one-sentence assertion*

2014 ◽  
Vol 7 (1) ◽  
pp. 36-67 ◽  
Author(s):  
YASUHIRO OZURU ◽  
DAVID BOWIE ◽  
GIULIA KAUFMAN
Keyword(s):  
Cognitive Processes ◽  
Experimental Studies ◽  
Cognitive Response ◽  
Response Options ◽  
Evaluative Response ◽  
Quasi Experimental ◽  
The Relationship

abstractThree quasi-experimental studies were conducted to investigate the relationship between the evaluative (i.e., agree/true) and the meta-cognitive (i.e., understand) response, and to determine which type of response people are more likely to provide when responding to one-sentence assertive statements. In Studies 1 and 2, participants performed two separate tasks in which they were asked to indicate the levels of: (i) understanding and (ii) agreement / perceived truthfulness of 126 one-sentence statements. The results indicated that participants were likely to provide a negative evaluative response (i.e., disagree/false) to a statement that they did not understand. In Study 3, participants were asked to evaluate the same 126 statements and choose between four response options: agree, disagree, understand, do not understand. The results indicated that people are more likely provide an evaluative response regardless of the understandability of a statement. The results of these studies are discussed in relation to (i) pragmatic perspective of how people infer speakers’ meaning, and (ii) cognitive processes underlying evaluative and meta-cognitive response.

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