scholarly journals Enhanced Non-Contact Grip Force and Swirl Stability by a Combined Venturi–Vortex Air Head

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7123
Author(s):  
Yung Hoon Lee ◽  
Joon Hyun Kim ◽  
Jaeyong Sung
Keyword(s):  
Grip Force ◽  
Coupled Model ◽  
Flow Patterns ◽  
Air Gap ◽  
Generation Efficiency ◽  
Vacuum Suction ◽  
Design Elements ◽  
Vortex Instability ◽  
Wide Range ◽  
Vacuum Generation

A combination of the venturi module and the vortex cup was proposed to solve vortex instability and to enhance grip capacity. Mounting a venturi suction pad inside the vortex cup improved vacuum generation efficiency. When the vortex cup properly maintained the non-contact air gap and generated an equivalent vacuum to achieve a sealing effect around the open gap of the suction pad, the combined head improved grip capacity and stabilized the non-contact environment. Furthermore, the flow patterns around the venturi chamber and the swirl inside the vortex cup were analyzed based on the design elements of each module. In a module that integrated some of the venturi’s features internally, increased air consumption of the vortex cup was required than that of the venturi. However, it supported a wide range of non-contact grips. The coupled model effectively protected the vacuum suction features of the venturi suction pad in all non-contact environments in that range.

scholarly journals Incorrect Asian aerosols affecting the attribution and projection of regional climate change in CMIP6 models

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Zhili Wang ◽  
Lei Lin ◽  
Yangyang Xu ◽  
Huizheng Che ◽  
Xiaoye Zhang ◽  
...  
Keyword(s):  
Climate Change ◽  
Radiative Forcing ◽  
Impact Analysis ◽  
Climate Model ◽  
Regional Climate ◽  
Eastern China ◽  
Coupled Model ◽  
Regional Climate Change ◽  
Anthropogenic Aerosol ◽  
Wide Range

AbstractAnthropogenic aerosol (AA) forcing has been shown as a critical driver of climate change over Asia since the mid-20th century. Here we show that almost all Coupled Model Intercomparison Project Phase 6 (CMIP6) models fail to capture the observed dipole pattern of aerosol optical depth (AOD) trends over Asia during 2006–2014, last decade of CMIP6 historical simulation, due to an opposite trend over eastern China compared with observations. The incorrect AOD trend over China is attributed to problematic AA emissions adopted by CMIP6. There are obvious differences in simulated regional aerosol radiative forcing and temperature responses over Asia when using two different emissions inventories (one adopted by CMIP6; the other from Peking university, a more trustworthy inventory) to driving a global aerosol-climate model separately. We further show that some widely adopted CMIP6 pathways (after 2015) also significantly underestimate the more recent decline in AA emissions over China. These flaws may bring about errors to the CMIP6-based regional climate attribution over Asia for the last two decades and projection for the next few decades, previously anticipated to inform a wide range of impact analysis.

A CFD Study of Focused Extreme Wave Impact on Decks of Offshore Structures

2014 ◽  
Author(s):  
Xin Lu ◽  
Pankaj Kumar ◽  
Anand Bahuguni ◽  
Yanling Wu
Keyword(s):  
Real World ◽  
Offshore Structures ◽  
Air Gap ◽  
Irregular Waves ◽  
Linear Wave ◽  
Extreme Wave ◽  
Wave Impact ◽  
Loading Test ◽  
Wide Range ◽  
Wave Maker

The design of offshore structures for extreme/abnormal waves assumes that there is sufficient air gap such that waves will not hit the platform deck. Due to inaccuracies in the predictions of extreme wave crests in addition to settlement or sea-level increases, the required air gap between the crest of the extreme wave and the deck is often inadequate in existing platforms and therefore wave-in-deck loads need to be considered when assessing the integrity of such platforms. The problem of wave-in-deck loading involves very complex physics and demands intensive study. In the Computational Fluid Mechanics (CFD) approach, two critical issues must be addressed, namely the efficient, realistic numerical wave maker and the accurate free surface capturing methodology. Most reported CFD research on wave-in-deck loads consider regular waves only, for instance the Stokes fifth-order waves. They are, however, recognized by designers as approximate approaches since “real world” sea states consist of random irregular waves. In our work, we report a recently developed focused extreme wave maker based on the NewWave theory. This model can better approximate the “real world” conditions, and is more efficient than conventional random wave makers. It is able to efficiently generate targeted waves at a prescribed time and location. The work is implemented and integrated with OpenFOAM, an open source platform that receives more and more attention in a wide range of industrial applications. We will describe the developed numerical method of predicting highly non-linear wave-in-deck loads in the time domain. The model’s capability is firstly demonstrated against 3D model testing experiments on a fixed block with various deck orientations under random waves. A detailed loading analysis is conducted and compared with available numerical and measurement data. It is then applied to an extreme wave loading test on a selected bridge with multiple under-deck girders. The waves are focused extreme irregular waves derived from NewWave theory and JONSWAP spectra.

Unsteady Conjugate Heat Transfer Investigation of a Multistage Steam Turbine in Warm-Keeping Operation With Hot Air

2018 ◽  
Author(s):  
Piotr Łuczyński ◽  
Dennis Toebben ◽  
Manfred Wirsum ◽  
Wolfgang F. D. Mohr ◽  
Klaus Helbig
Keyword(s):  
Heat Transfer ◽  
Conjugate Heat Transfer ◽  
Flow Patterns ◽  
Operating Conditions ◽  
Angle Of Incidence ◽  
Time Step ◽  
Hot Air ◽  
Wide Range ◽  
Vortex Systems ◽  
Operating Points

In recent decades, the rising share of commonly subsidized renewable energy especially affects the operational strategy of conventional power plants. In pursuit of flexibility improvements, extension of life cycle, in addition to a reduction in start-up time, General Electric has developed a product to warm-keep high/intermediate pressure steam turbines using hot air. In order to optimize the warm-keeping operation and to gain knowledge about the dominant heat transfer phenomena and flow structures, detailed numerical investigations are required. Considering specific warm-keeping operating conditions characterized by high turbulent flows, it is required to conduct calculations based on time-consuming unsteady conjugate heat transfer (CHT) simulations. In order to investigate the warm-keeping process as found in the presented research, single and multistage numerical turbine models were developed. Furthermore, an innovative calculation approach called the Equalized Timescales Method (ET) was applied for the modeling of unsteady conjugate heat transfer (CHT). The unsteady approach improves the accuracy of the stationary simulations and enables the determination of the multistage turbine models. In the course of the research, two particular input variables of the ET approach — speed up factor (SF) and time step (TS) — have been additionally investigated with regard to their high impact on the calculation time and the quality of the results. Using the ET method, the mass flow rate and the rotational speed were varied to generate a database of warm-keeping operating points. The main goal of this work is to provide a comprehensive knowledge of the flow field and heat transfer in a wide range of turbine warm-keeping operations and to characterize the flow patterns observed at these operating points. For varying values of flow coefficient and angle of incidence, the secondary flow phenomena change from well-known vortex systems occurring in design operation (such as passage, horseshoe and corner vortices) to effects typical for windage, like patterns of alternating vortices and strong backflows. Furthermore, the identified flow patterns have been compared to vortex systems described in cited literature and summarized in the so-called blade vortex diagram. The comparison of heat transfer in the form of charts showing the variation of the Nusselt-numbers with respect to changes in angle of incidence and flow coefficients at specific operating points is additionally provided.

scholarly journals Characteristics of registered clinical trials assessing treatments for COVID-19: a cross-sectional analysis

BMJ Open ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. e039978 ◽  
Author(s):  
Hemalkumar B Mehta ◽  
Stephan Ehrhardt ◽  
Thomas J Moore ◽  
Jodi B Segal ◽  
G Caleb Alexander
Keyword(s):  
Clinical Trials ◽  
Clinical Investigation ◽  
Scientific Progress ◽  
Cross Sectional ◽  
Design Elements ◽  
Cross Sectional Analysis ◽  
Therapeutic Benefits ◽  
Wide Range ◽  
The Usa ◽  
Sectional Analysis

ObjectivesThe coronavirus disease 2019 (COVID-19) pandemic has prompted many initiatives to identify safe and efficacious treatments, yet little is known regarding where early efforts have focused. We aimed to characterise registered clinical trials assessing drugs or plasma treatments for COVID-19.Design, setting and participantsCross-sectional analysis of clinical trials for the treatment of COVID-19 that were registered in the USA or in countries contributing to the WHO’s International Clinical Trials Registry Platform. Relevant trial entries of drugs or plasma were downloaded on 26 March 2020, deduplicated, verified with reviews of major medical journals and WHO websites and independently analysed by two reviewers.Main outcome(s)Trial intervention, sponsorship, critical design elements and specified outcomesResultsOverall, 201 clinical trials were registered for testing the therapeutic benefits of 92 drugs or plasma, including 64 in monotherapy and 28 different combinations. Only eight (8.7%) products or combinations involved new molecular entities. The other test therapies had a wide range of prior medical uses, including as antivirals, antimalarials, immunosuppressants and oncology treatments. In 152 trials (75.7%), patients were randomised to treatment or comparator, including 55 trials with some form of blinding and 97 open-label studies. The 49 (24.4%) of trials without a randomised design included 29 single armed studies and 20 trials with some comparison group. Most trial designs featured multiple endpoints. Clinical endpoints were identified in 134 (66.7%) of trials and included COVID-19 symptoms, death, recovery, required intensive care and hospital discharge. Clinical scales were being used in 33 (16.4%) trials, most often measures of oxygenation and critical illness. Surrogate endpoints or biomarkers were studied in 88 (42.3%) of trials, primarily assays of viral load. Although the trials were initiated in more than 17 countries or regions, 100 (49.8%) were registered in China and 78 (37.8%) in the USA. Registered trials increased rapidly, with the number of registered trials doubling from 1 March to 26 March 2020.ConclusionsWhile accelerating morbidity and mortality from the COVID-19 pandemic has been paralleled by early and rapid clinical investigation, many trials lack features to optimise their scientific value. Global coordination and increased funding of high-quality research may help to maximise scientific progress in rapidly discovering safe and effective treatments.

scholarly journals Design Elements and Electrical Performance of a Bifacial BIPV Module

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Jun-Gu Kang ◽  
Jin-Hee Kim ◽  
Jun-Tae Kim
Keyword(s):  
Solar Cells ◽  
Glass Structure ◽  
Building Envelope ◽  
Electrical Performance ◽  
Design Elements ◽  
Pv Module ◽  
Wide Range ◽  
Dark Color ◽  
Module Performance ◽  
Space Ratio

Bifacial BIPV systems have great potential when applied to buildings given their use of a glass-to-glass structure. However, the performance of bifacial solar cells depends on a variety of design factors. Therefore, in order to apply bifacial solar cells to buildings, a bifacial PV module performance analysis should be carried out, including consideration of the various design elements and reflecting a wide range of installation conditions. This study focuses on the performance of a bifacial BIPV module applied to a building envelope. The results here show that the design elements of reflectivity and the transparent space ratio have the greatest impact on performance levels. The distance between the module and the wall had less of an impact on performance. The bifacial BIPV module produced output up to 30% greater than the output of monofacial PV modules, depending on the design elements. Bifacial BIPV modules themselves should have transparent space ratios of at least 30%. When a dark color is used on the external wall with reflectivity of 50% or less, bifacial BIPV modules with transparent space ratios of 40% and above should be used. In order to achieve higher performance through the installation of bifacial BIPV modules, design conditions which facilitate reflectivity exceeding 50% and a transparent space ratio which exceeds 30% must be met.

scholarly journals Description and basic evaluation of simulated mean state, internal variability, and climate sensitivity in MIROC6

2019 ◽  
Vol 12 (7) ◽  
pp. 2727-2765 ◽  
Author(s):  
Hiroaki Tatebe ◽  
Tomoo Ogura ◽  
Tomoko Nitta ◽  
Yoshiki Komuro ◽  
Koji Ogochi ◽  
...  
Keyword(s):  
Climate Variability ◽  
Climate Sensitivity ◽  
Radiative Forcing ◽  
Climate Model ◽  
Coupled Model ◽  
Climate Feedback ◽  
Climate Projections ◽  
Internal Climate Variability ◽  
Wide Range ◽  
Mean Climate

Abstract. The sixth version of the Model for Interdisciplinary Research on Climate (MIROC), called MIROC6, was cooperatively developed by a Japanese modeling community. In the present paper, simulated mean climate, internal climate variability, and climate sensitivity in MIROC6 are evaluated and briefly summarized in comparison with the previous version of our climate model (MIROC5) and observations. The results show that the overall reproducibility of mean climate and internal climate variability in MIROC6 is better than that in MIROC5. The tropical climate systems (e.g., summertime precipitation in the western Pacific and the eastward-propagating Madden–Julian oscillation) and the midlatitude atmospheric circulation (e.g., the westerlies, the polar night jet, and troposphere–stratosphere interactions) are significantly improved in MIROC6. These improvements can be attributed to the newly implemented parameterization for shallow convective processes and to the inclusion of the stratosphere. While there are significant differences in climates and variabilities between the two models, the effective climate sensitivity of 2.6 K remains the same because the differences in radiative forcing and climate feedback tend to offset each other. With an aim towards contributing to the sixth phase of the Coupled Model Intercomparison Project, designated simulations tackling a wide range of climate science issues, as well as seasonal to decadal climate predictions and future climate projections, are currently ongoing using MIROC6.

Viscous Oil-Water Flow in a Microchannel: Flow Patterns and Flow Development

2010 ◽  
Author(s):  
Hooman Foroughi ◽  
Masahiro Kawaji
Keyword(s):  
Water Flow ◽  
Silicone Oil ◽  
Flow Characteristics ◽  
Flow Patterns ◽  
Fused Silica ◽  
Water Mixture ◽  
Injection Point ◽  
Viscous Oil ◽  
Wide Range ◽  
Oil Water

The flow characteristics of a highly viscous oil and water mixture in a circular microchannel have been investigated. Water and silicone oil with a viscosity of 863 mPa.s were injected into a fused silica microchannel with a diameter of 250 μm. Before each experiment, the microchannel was initially saturated with either oil or water. In the initially oil-saturated case, different liquid-liquid flow patterns were observed and classified over a wide range of oil and water flow rates. As a special case, the flow of water at zero oil flow rate in a microchannel initially filled with silicone oil was also studied. When the microchannel was initially saturated with water, the oil formed a jet in water at the injection point but developed an instability at the oil-water interface downstream and eventually broke up into droplets.

Unsteady Conjugate Heat Transfer Investigation of a Multistage Steam Turbine in Warm-Keeping Operation With Hot Air

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Piotr Łuczyński ◽  
Dennis Toebben ◽  
Manfred Wirsum ◽  
Wolfgang F. D. Mohr ◽  
Klaus Helbig
Keyword(s):  
Heat Transfer ◽  
Conjugate Heat Transfer ◽  
Flow Patterns ◽  
Flow Coefficient ◽  
Angle Of Incidence ◽  
Steam Turbines ◽  
Hot Air ◽  
Wide Range ◽  
Vortex Systems ◽  
Operating Points

In pursuit of flexibility improvements, General Electric has developed a product to warm-keep high/intermediate pressure steam turbines using hot air. In order to optimize the warm-keeping operation and to gain knowledge about the dominant heat transfer phenomena and flow structures, detailed numerical investigations are required. For the sake of the investigation of the warm-keeping process as found in the presented research, single and multistage numerical turbine models were developed. Furthermore, an innovative calculation approach called the equalized timescales method (ET) was applied for the modeling of unsteady conjugate heat transfer (CHT). In the course of the research, the setup of the ET approach has been additionally investigated. Using the ET method, the mass flow rate and the rotational speed were varied to generate a database of warm-keeping operating points. The main goal of this work is to provide a comprehensive knowledge of the flow field and heat transfer in a wide range of turbine warm-keeping operations and to characterize the flow patterns observed at these operating points. For varying values of flow coefficient and angle of incidence, the secondary flow phenomena change from well-known vortex systems occurring in design operation to effects typical for windage, like patterns of alternating vortices and strong backflows. Furthermore, the identified flow patterns have been compared to vortex systems described in cited literature and summarized in the so-called blade vortex diagram. The analysis of heat transfer in turbine warm-keeping operation is additionally provided.

Visual Literacy

2017 ◽  
Author(s):  
Frank Serafini
Keyword(s):  
Social Sciences ◽  
Cognitive Abilities ◽  
Cognitive Skills ◽  
Social Practice ◽  
Visual Literacy ◽  
Social Contexts ◽  
Visual Images ◽  
Design Elements ◽  
The Social ◽  
Wide Range

Visual literacy was originally defined as a set of visual competencies or cognitive skills and strategies one needs to make sense of visual images. These visual competencies were seen as universal cognitive abilities that were used for understanding visual images regardless of the contexts of production, reception, and dissemination. More contemporary definitions suggest visual literacy is a contextualized, social practice as much as an individualized, cognitively based set of competencies. Visual literacy is more aptly defined as a process of generating meanings in transaction with multimodal ensembles that include written text, visual images, and design elements from a variety of perspectives to meet the requirements of particular social contexts. Theories of visual literacy and associated research and pedagogy draw from a wide range of disciplines including art history, semiotics, media and cultural studies, communication studies, visual ethnography and anthropology, social semiotics, new literacies studies, cognitive psychology, and critical theory. Understanding the various theories, research methodologies, and pedagogical approaches to visual literacy requires an investigation into how the various paradigm shifts that have occurred in the social sciences have affected this field of study. Cognitive, linguistic, sociocultural, multimodal, and postmodern “turns” in the social sciences each bring different theories, perspectives, and approaches to the field of visual literacy. Visual literacy now incorporates sociocultural, semiotic, critical, and multimodal perspectives to understand the meaning potential of the visual and verbal ensembles encountered in social environments.

scholarly journals Mercury, Arsenic and Lead Removal by Air Gap Membrane Distillation: Experimental Study

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1574 ◽  
Author(s):  
Abdullah Alkhudhiri ◽  
Mohammed Hakami ◽  
Myrto-Panagiota Zacharof ◽  
Hosam Abu Homod ◽  
Ahmed Alsadun
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Removal Efficiency ◽  
Membrane Distillation ◽  
Air Gap ◽  
Lead Removal ◽  
Membrane Pore ◽  
Pore Sizes ◽  
Air Gap Membrane Distillation ◽  
Wide Range

Synthetic industrial wastewater samples containing mercury (Hg), arsenic (As), and lead (Pb) ions in various concentrations were prepared and treated by air gap membrane distillation (AGMD), a promising method for heavy metals removal. Three different membrane pore sizes (0.2, 0.45, and 1 μm) which are commercially available (TF200, TF450, and TF1000) were tested to assess their effectiveness in combination with various heavy metal concentrations and operating parameters (flow rate 1–5 L/min, feed temperature 40–70 °C, and pH 2–11). The results indicated that a high removal efficiency of the heavy metals was achieved by AGMD. TF200 and TF450 showed excellent membrane removal efficiency, which was above 96% for heavy metal ions in a wide range of concentrations. In addition, there was no significant influence of the pH value on the metal removal efficiency. Energy consumption was monitored at different membrane pore sizes and was found to be almost independent of membrane pore size and metal type.

Sign in / Sign up

Export Citation Format

Share Document