2D CFD Code Based on MATLAB- As Good As FLUENT!Jiannan Tan
This document introduces the author's 2D CFD code. It uses an unstructured grid approach and solves the Navier-Stokes equations to calculate velocity and pressure fields. The code is validated against commercial software FLUENT for several benchmark cases including flow in a straight pipe, sudden expansion jet flow, Z-pipe flow, and flow over a square cylinder. Results show good agreement with FLUENT in terms of velocity profiles and vortex structures.
Flow and Noise Simulation of the NASA Tandem Cylinder Experiment using OpenFOAMCon Doolan
The document summarizes flow and noise simulations of the NASA tandem cylinder experiment using OpenFOAM software. It aims to present URANS aerodynamic simulations comparing results to experimental data, and to predict noise using a statistical method. Surface pressures are used to calculate noise by Curle's theory with temporal and spatial phase dispersion models. Mean flow results agree reasonably well with PIV experiments, while acoustic predictions are assessed against experimental noise data.
This document provides a summary of a dissertation submitted for a Bachelor of Engineering Honours degree. The dissertation involves computational fluid dynamics (CFD) analysis of aerodynamic forces on a rear spoiler for a car model in 2D. The document includes acknowledgments, a declaration by the author, a table of contents, and 6 chapters that describe the background, literature review, methodology, numerical setup, CFD results and analysis, and conclusions. The CFD analysis is conducted using ANSYS software to simulate airflow around baseline models of a car with and without different rear spoiler configurations.
In cylinder cold flow cfd simulation of ic engine using hybrid approacheSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
The document provides information on fundamental hydraulic systems and their components. It discusses the basic principles and advantages of hydraulic systems over mechanical systems. It then describes the basic components of hydraulic systems including reservoirs, strainers, filters, accumulators, pressure gauges, flow meters, and pumps. It provides diagrams and explanations of how different types of hydraulic systems and components work.
2024 State of Marketing Report – by HubspotMarius Sescu
https://www.hubspot.com/state-of-marketing
· Scaling relationships and proving ROI
· Social media is the place for search, sales, and service
· Authentic influencer partnerships fuel brand growth
· The strongest connections happen via call, click, chat, and camera.
· Time saved with AI leads to more creative work
· Seeking: A single source of truth
· TLDR; Get on social, try AI, and align your systems.
· More human marketing, powered by robots
ChatGPT is a revolutionary addition to the world since its introduction in 2022. A big shift in the sector of information gathering and processing happened because of this chatbot. What is the story of ChatGPT? How is the bot responding to prompts and generating contents? Swipe through these slides prepared by Expeed Software, a web development company regarding the development and technical intricacies of ChatGPT!
2D CFD Code Based on MATLAB- As Good As FLUENT!Jiannan Tan
This document introduces the author's 2D CFD code. It uses an unstructured grid approach and solves the Navier-Stokes equations to calculate velocity and pressure fields. The code is validated against commercial software FLUENT for several benchmark cases including flow in a straight pipe, sudden expansion jet flow, Z-pipe flow, and flow over a square cylinder. Results show good agreement with FLUENT in terms of velocity profiles and vortex structures.
Flow and Noise Simulation of the NASA Tandem Cylinder Experiment using OpenFOAMCon Doolan
The document summarizes flow and noise simulations of the NASA tandem cylinder experiment using OpenFOAM software. It aims to present URANS aerodynamic simulations comparing results to experimental data, and to predict noise using a statistical method. Surface pressures are used to calculate noise by Curle's theory with temporal and spatial phase dispersion models. Mean flow results agree reasonably well with PIV experiments, while acoustic predictions are assessed against experimental noise data.
This document provides a summary of a dissertation submitted for a Bachelor of Engineering Honours degree. The dissertation involves computational fluid dynamics (CFD) analysis of aerodynamic forces on a rear spoiler for a car model in 2D. The document includes acknowledgments, a declaration by the author, a table of contents, and 6 chapters that describe the background, literature review, methodology, numerical setup, CFD results and analysis, and conclusions. The CFD analysis is conducted using ANSYS software to simulate airflow around baseline models of a car with and without different rear spoiler configurations.
In cylinder cold flow cfd simulation of ic engine using hybrid approacheSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
The document provides information on fundamental hydraulic systems and their components. It discusses the basic principles and advantages of hydraulic systems over mechanical systems. It then describes the basic components of hydraulic systems including reservoirs, strainers, filters, accumulators, pressure gauges, flow meters, and pumps. It provides diagrams and explanations of how different types of hydraulic systems and components work.
2024 State of Marketing Report – by HubspotMarius Sescu
https://www.hubspot.com/state-of-marketing
· Scaling relationships and proving ROI
· Social media is the place for search, sales, and service
· Authentic influencer partnerships fuel brand growth
· The strongest connections happen via call, click, chat, and camera.
· Time saved with AI leads to more creative work
· Seeking: A single source of truth
· TLDR; Get on social, try AI, and align your systems.
· More human marketing, powered by robots
ChatGPT is a revolutionary addition to the world since its introduction in 2022. A big shift in the sector of information gathering and processing happened because of this chatbot. What is the story of ChatGPT? How is the bot responding to prompts and generating contents? Swipe through these slides prepared by Expeed Software, a web development company regarding the development and technical intricacies of ChatGPT!
Mechanisms and Applications of Antiviral Neutralizing Antibodies - Creative B...Creative-Biolabs
Neutralizing antibodies, pivotal in immune defense, specifically bind and inhibit viral pathogens, thereby playing a crucial role in protecting against and mitigating infectious diseases. In this slide, we will introduce what antibodies and neutralizing antibodies are, the production and regulation of neutralizing antibodies, their mechanisms of action, classification and applications, as well as the challenges they face.
Microbial interaction
Microorganisms interacts with each other and can be physically associated with another organisms in a variety of ways.
One organism can be located on the surface of another organism as an ectobiont or located within another organism as endobiont.
Microbial interaction may be positive such as mutualism, proto-cooperation, commensalism or may be negative such as parasitism, predation or competition
Types of microbial interaction
Positive interaction: mutualism, proto-cooperation, commensalism
Negative interaction: Ammensalism (antagonism), parasitism, predation, competition
I. Mutualism:
It is defined as the relationship in which each organism in interaction gets benefits from association. It is an obligatory relationship in which mutualist and host are metabolically dependent on each other.
Mutualistic relationship is very specific where one member of association cannot be replaced by another species.
Mutualism require close physical contact between interacting organisms.
Relationship of mutualism allows organisms to exist in habitat that could not occupied by either species alone.
Mutualistic relationship between organisms allows them to act as a single organism.
Examples of mutualism:
i. Lichens:
Lichens are excellent example of mutualism.
They are the association of specific fungi and certain genus of algae. In lichen, fungal partner is called mycobiont and algal partner is called
II. Syntrophism:
It is an association in which the growth of one organism either depends on or improved by the substrate provided by another organism.
In syntrophism both organism in association gets benefits.
Compound A
Utilized by population 1
Compound B
Utilized by population 2
Compound C
utilized by both Population 1+2
Products
In this theoretical example of syntrophism, population 1 is able to utilize and metabolize compound A, forming compound B but cannot metabolize beyond compound B without co-operation of population 2. Population 2is unable to utilize compound A but it can metabolize compound B forming compound C. Then both population 1 and 2 are able to carry out metabolic reaction which leads to formation of end product that neither population could produce alone.
Examples of syntrophism:
i. Methanogenic ecosystem in sludge digester
Methane produced by methanogenic bacteria depends upon interspecies hydrogen transfer by other fermentative bacteria.
Anaerobic fermentative bacteria generate CO2 and H2 utilizing carbohydrates which is then utilized by methanogenic bacteria (Methanobacter) to produce methane.
ii. Lactobacillus arobinosus and Enterococcus faecalis:
In the minimal media, Lactobacillus arobinosus and Enterococcus faecalis are able to grow together but not alone.
The synergistic relationship between E. faecalis and L. arobinosus occurs in which E. faecalis require folic acid
PPT on Alternate Wetting and Drying presented at the three-day 'Training and Validation Workshop on Modules of Climate Smart Agriculture (CSA) Technologies in South Asia' workshop on April 22, 2024.
Immersive Learning That Works: Research Grounding and Paths ForwardLeonel Morgado
We will metaverse into the essence of immersive learning, into its three dimensions and conceptual models. This approach encompasses elements from teaching methodologies to social involvement, through organizational concerns and technologies. Challenging the perception of learning as knowledge transfer, we introduce a 'Uses, Practices & Strategies' model operationalized by the 'Immersive Learning Brain' and ‘Immersion Cube’ frameworks. This approach offers a comprehensive guide through the intricacies of immersive educational experiences and spotlighting research frontiers, along the immersion dimensions of system, narrative, and agency. Our discourse extends to stakeholders beyond the academic sphere, addressing the interests of technologists, instructional designers, and policymakers. We span various contexts, from formal education to organizational transformation to the new horizon of an AI-pervasive society. This keynote aims to unite the iLRN community in a collaborative journey towards a future where immersive learning research and practice coalesce, paving the way for innovative educational research and practice landscapes.
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...Sérgio Sacani
Context. The observation of several L-band emission sources in the S cluster has led to a rich discussion of their nature. However, a definitive answer to the classification of the dusty objects requires an explanation for the detection of compact Doppler-shifted Brγ emission. The ionized hydrogen in combination with the observation of mid-infrared L-band continuum emission suggests that most of these sources are embedded in a dusty envelope. These embedded sources are part of the S-cluster, and their relationship to the S-stars is still under debate. To date, the question of the origin of these two populations has been vague, although all explanations favor migration processes for the individual cluster members. Aims. This work revisits the S-cluster and its dusty members orbiting the supermassive black hole SgrA* on bound Keplerian orbits from a kinematic perspective. The aim is to explore the Keplerian parameters for patterns that might imply a nonrandom distribution of the sample. Additionally, various analytical aspects are considered to address the nature of the dusty sources. Methods. Based on the photometric analysis, we estimated the individual H−K and K−L colors for the source sample and compared the results to known cluster members. The classification revealed a noticeable contrast between the S-stars and the dusty sources. To fit the flux-density distribution, we utilized the radiative transfer code HYPERION and implemented a young stellar object Class I model. We obtained the position angle from the Keplerian fit results; additionally, we analyzed the distribution of the inclinations and the longitudes of the ascending node. Results. The colors of the dusty sources suggest a stellar nature consistent with the spectral energy distribution in the near and midinfrared domains. Furthermore, the evaporation timescales of dusty and gaseous clumps in the vicinity of SgrA* are much shorter ( 2yr) than the epochs covered by the observations (≈15yr). In addition to the strong evidence for the stellar classification of the D-sources, we also find a clear disk-like pattern following the arrangements of S-stars proposed in the literature. Furthermore, we find a global intrinsic inclination for all dusty sources of 60 ± 20◦, implying a common formation process. Conclusions. The pattern of the dusty sources manifested in the distribution of the position angles, inclinations, and longitudes of the ascending node strongly suggests two different scenarios: the main-sequence stars and the dusty stellar S-cluster sources share a common formation history or migrated with a similar formation channel in the vicinity of SgrA*. Alternatively, the gravitational influence of SgrA* in combination with a massive perturber, such as a putative intermediate mass black hole in the IRS 13 cluster, forces the dusty objects and S-stars to follow a particular orbital arrangement. Key words. stars: black holes– stars: formation– Galaxy: center– galaxies: star formation
Anti-Universe And Emergent Gravity and the Dark UniverseSérgio Sacani
Recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. These ideas are best understood in Anti-de Sitter space, where they rely on the area law for entanglement entropy. The extension to de Sitter space requires taking into account the entropy and temperature associated with the cosmological horizon. Using insights from string theory, black hole physics and quantum information theory we argue that the positive dark energy leads to a thermal volume law contribution to the entropy that overtakes the area law precisely at the cosmological horizon. Due to the competition between area and volume law entanglement the microscopic de Sitter states do not thermalise at sub-Hubble scales: they exhibit memory effects in the form of an entropy displacement caused by matter. The emergent laws of gravity contain an additional ‘dark’ gravitational force describing the ‘elastic’ response due to the entropy displacement. We derive an estimate of the strength of this extra force in terms of the baryonic mass, Newton’s constant and the Hubble acceleration scale a0 = cH0, and provide evidence for the fact that this additional ‘dark gravity force’ explains the observed phenomena in galaxies and clusters currently attributed to dark matter.
The cost of acquiring information by natural selectionCarl Bergstrom
This is a short talk that I gave at the Banff International Research Station workshop on Modeling and Theory in Population Biology. The idea is to try to understand how the burden of natural selection relates to the amount of information that selection puts into the genome.
It's based on the first part of this research paper:
The cost of information acquisition by natural selection
Ryan Seamus McGee, Olivia Kosterlitz, Artem Kaznatcheev, Benjamin Kerr, Carl T. Bergstrom
bioRxiv 2022.07.02.498577; doi: https://doi.org/10.1101/2022.07.02.498577
Authoring a personal GPT for your research and practice: How we created the Q...Leonel Morgado
Thematic analysis in qualitative research is a time-consuming and systematic task, typically done using teams. Team members must ground their activities on common understandings of the major concepts underlying the thematic analysis, and define criteria for its development. However, conceptual misunderstandings, equivocations, and lack of adherence to criteria are challenges to the quality and speed of this process. Given the distributed and uncertain nature of this process, we wondered if the tasks in thematic analysis could be supported by readily available artificial intelligence chatbots. Our early efforts point to potential benefits: not just saving time in the coding process but better adherence to criteria and grounding, by increasing triangulation between humans and artificial intelligence. This tutorial will provide a description and demonstration of the process we followed, as two academic researchers, to develop a custom ChatGPT to assist with qualitative coding in the thematic data analysis process of immersive learning accounts in a survey of the academic literature: QUAL-E Immersive Learning Thematic Analysis Helper. In the hands-on time, participants will try out QUAL-E and develop their ideas for their own qualitative coding ChatGPT. Participants that have the paid ChatGPT Plus subscription can create a draft of their assistants. The organizers will provide course materials and slide deck that participants will be able to utilize to continue development of their custom GPT. The paid subscription to ChatGPT Plus is not required to participate in this workshop, just for trying out personal GPTs during it.
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...Advanced-Concepts-Team
Presentation in the Science Coffee of the Advanced Concepts Team of the European Space Agency on the 07.06.2024.
Speaker: Diego Blas (IFAE/ICREA)
Title: Gravitational wave detection with orbital motion of Moon and artificial
Abstract:
In this talk I will describe some recent ideas to find gravitational waves from supermassive black holes or of primordial origin by studying their secular effect on the orbital motion of the Moon or satellites that are laser ranged.
Product Design Trends in 2024 | Teenage EngineeringsPixeldarts
The realm of product design is a constantly changing environment where technology and style intersect. Every year introduces fresh challenges and exciting trends that mold the future of this captivating art form. In this piece, we delve into the significant trends set to influence the look and functionality of product design in the year 2024.
How Race, Age and Gender Shape Attitudes Towards Mental HealthThinkNow
Mental health has been in the news quite a bit lately. Dozens of U.S. states are currently suing Meta for contributing to the youth mental health crisis by inserting addictive features into their products, while the U.S. Surgeon General is touring the nation to bring awareness to the growing epidemic of loneliness and isolation. The country has endured periods of low national morale, such as in the 1970s when high inflation and the energy crisis worsened public sentiment following the Vietnam War. The current mood, however, feels different. Gallup recently reported that national mental health is at an all-time low, with few bright spots to lift spirits.
To better understand how Americans are feeling and their attitudes towards mental health in general, ThinkNow conducted a nationally representative quantitative survey of 1,500 respondents and found some interesting differences among ethnic, age and gender groups.
Technology
For example, 52% agree that technology and social media have a negative impact on mental health, but when broken out by race, 61% of Whites felt technology had a negative effect, and only 48% of Hispanics thought it did.
While technology has helped us keep in touch with friends and family in faraway places, it appears to have degraded our ability to connect in person. Staying connected online is a double-edged sword since the same news feed that brings us pictures of the grandkids and fluffy kittens also feeds us news about the wars in Israel and Ukraine, the dysfunction in Washington, the latest mass shooting and the climate crisis.
Hispanics may have a built-in defense against the isolation technology breeds, owing to their large, multigenerational households, strong social support systems, and tendency to use social media to stay connected with relatives abroad.
Age and Gender
When asked how individuals rate their mental health, men rate it higher than women by 11 percentage points, and Baby Boomers rank it highest at 83%, saying it’s good or excellent vs. 57% of Gen Z saying the same.
Gen Z spends the most amount of time on social media, so the notion that social media negatively affects mental health appears to be correlated. Unfortunately, Gen Z is also the generation that’s least comfortable discussing mental health concerns with healthcare professionals. Only 40% of them state they’re comfortable discussing their issues with a professional compared to 60% of Millennials and 65% of Boomers.
Race Affects Attitudes
As seen in previous research conducted by ThinkNow, Asian Americans lag other groups when it comes to awareness of mental health issues. Twenty-four percent of Asian Americans believe that having a mental health issue is a sign of weakness compared to the 16% average for all groups. Asians are also considerably less likely to be aware of mental health services in their communities (42% vs. 55%) and most likely to seek out information on social media (51% vs. 35%).
Mechanisms and Applications of Antiviral Neutralizing Antibodies - Creative B...Creative-Biolabs
Neutralizing antibodies, pivotal in immune defense, specifically bind and inhibit viral pathogens, thereby playing a crucial role in protecting against and mitigating infectious diseases. In this slide, we will introduce what antibodies and neutralizing antibodies are, the production and regulation of neutralizing antibodies, their mechanisms of action, classification and applications, as well as the challenges they face.
Microbial interaction
Microorganisms interacts with each other and can be physically associated with another organisms in a variety of ways.
One organism can be located on the surface of another organism as an ectobiont or located within another organism as endobiont.
Microbial interaction may be positive such as mutualism, proto-cooperation, commensalism or may be negative such as parasitism, predation or competition
Types of microbial interaction
Positive interaction: mutualism, proto-cooperation, commensalism
Negative interaction: Ammensalism (antagonism), parasitism, predation, competition
I. Mutualism:
It is defined as the relationship in which each organism in interaction gets benefits from association. It is an obligatory relationship in which mutualist and host are metabolically dependent on each other.
Mutualistic relationship is very specific where one member of association cannot be replaced by another species.
Mutualism require close physical contact between interacting organisms.
Relationship of mutualism allows organisms to exist in habitat that could not occupied by either species alone.
Mutualistic relationship between organisms allows them to act as a single organism.
Examples of mutualism:
i. Lichens:
Lichens are excellent example of mutualism.
They are the association of specific fungi and certain genus of algae. In lichen, fungal partner is called mycobiont and algal partner is called
II. Syntrophism:
It is an association in which the growth of one organism either depends on or improved by the substrate provided by another organism.
In syntrophism both organism in association gets benefits.
Compound A
Utilized by population 1
Compound B
Utilized by population 2
Compound C
utilized by both Population 1+2
Products
In this theoretical example of syntrophism, population 1 is able to utilize and metabolize compound A, forming compound B but cannot metabolize beyond compound B without co-operation of population 2. Population 2is unable to utilize compound A but it can metabolize compound B forming compound C. Then both population 1 and 2 are able to carry out metabolic reaction which leads to formation of end product that neither population could produce alone.
Examples of syntrophism:
i. Methanogenic ecosystem in sludge digester
Methane produced by methanogenic bacteria depends upon interspecies hydrogen transfer by other fermentative bacteria.
Anaerobic fermentative bacteria generate CO2 and H2 utilizing carbohydrates which is then utilized by methanogenic bacteria (Methanobacter) to produce methane.
ii. Lactobacillus arobinosus and Enterococcus faecalis:
In the minimal media, Lactobacillus arobinosus and Enterococcus faecalis are able to grow together but not alone.
The synergistic relationship between E. faecalis and L. arobinosus occurs in which E. faecalis require folic acid
PPT on Alternate Wetting and Drying presented at the three-day 'Training and Validation Workshop on Modules of Climate Smart Agriculture (CSA) Technologies in South Asia' workshop on April 22, 2024.
Immersive Learning That Works: Research Grounding and Paths ForwardLeonel Morgado
We will metaverse into the essence of immersive learning, into its three dimensions and conceptual models. This approach encompasses elements from teaching methodologies to social involvement, through organizational concerns and technologies. Challenging the perception of learning as knowledge transfer, we introduce a 'Uses, Practices & Strategies' model operationalized by the 'Immersive Learning Brain' and ‘Immersion Cube’ frameworks. This approach offers a comprehensive guide through the intricacies of immersive educational experiences and spotlighting research frontiers, along the immersion dimensions of system, narrative, and agency. Our discourse extends to stakeholders beyond the academic sphere, addressing the interests of technologists, instructional designers, and policymakers. We span various contexts, from formal education to organizational transformation to the new horizon of an AI-pervasive society. This keynote aims to unite the iLRN community in a collaborative journey towards a future where immersive learning research and practice coalesce, paving the way for innovative educational research and practice landscapes.
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...Sérgio Sacani
Context. The observation of several L-band emission sources in the S cluster has led to a rich discussion of their nature. However, a definitive answer to the classification of the dusty objects requires an explanation for the detection of compact Doppler-shifted Brγ emission. The ionized hydrogen in combination with the observation of mid-infrared L-band continuum emission suggests that most of these sources are embedded in a dusty envelope. These embedded sources are part of the S-cluster, and their relationship to the S-stars is still under debate. To date, the question of the origin of these two populations has been vague, although all explanations favor migration processes for the individual cluster members. Aims. This work revisits the S-cluster and its dusty members orbiting the supermassive black hole SgrA* on bound Keplerian orbits from a kinematic perspective. The aim is to explore the Keplerian parameters for patterns that might imply a nonrandom distribution of the sample. Additionally, various analytical aspects are considered to address the nature of the dusty sources. Methods. Based on the photometric analysis, we estimated the individual H−K and K−L colors for the source sample and compared the results to known cluster members. The classification revealed a noticeable contrast between the S-stars and the dusty sources. To fit the flux-density distribution, we utilized the radiative transfer code HYPERION and implemented a young stellar object Class I model. We obtained the position angle from the Keplerian fit results; additionally, we analyzed the distribution of the inclinations and the longitudes of the ascending node. Results. The colors of the dusty sources suggest a stellar nature consistent with the spectral energy distribution in the near and midinfrared domains. Furthermore, the evaporation timescales of dusty and gaseous clumps in the vicinity of SgrA* are much shorter ( 2yr) than the epochs covered by the observations (≈15yr). In addition to the strong evidence for the stellar classification of the D-sources, we also find a clear disk-like pattern following the arrangements of S-stars proposed in the literature. Furthermore, we find a global intrinsic inclination for all dusty sources of 60 ± 20◦, implying a common formation process. Conclusions. The pattern of the dusty sources manifested in the distribution of the position angles, inclinations, and longitudes of the ascending node strongly suggests two different scenarios: the main-sequence stars and the dusty stellar S-cluster sources share a common formation history or migrated with a similar formation channel in the vicinity of SgrA*. Alternatively, the gravitational influence of SgrA* in combination with a massive perturber, such as a putative intermediate mass black hole in the IRS 13 cluster, forces the dusty objects and S-stars to follow a particular orbital arrangement. Key words. stars: black holes– stars: formation– Galaxy: center– galaxies: star formation
Anti-Universe And Emergent Gravity and the Dark UniverseSérgio Sacani
Recent theoretical progress indicates that spacetime and gravity emerge together from the entanglement structure of an underlying microscopic theory. These ideas are best understood in Anti-de Sitter space, where they rely on the area law for entanglement entropy. The extension to de Sitter space requires taking into account the entropy and temperature associated with the cosmological horizon. Using insights from string theory, black hole physics and quantum information theory we argue that the positive dark energy leads to a thermal volume law contribution to the entropy that overtakes the area law precisely at the cosmological horizon. Due to the competition between area and volume law entanglement the microscopic de Sitter states do not thermalise at sub-Hubble scales: they exhibit memory effects in the form of an entropy displacement caused by matter. The emergent laws of gravity contain an additional ‘dark’ gravitational force describing the ‘elastic’ response due to the entropy displacement. We derive an estimate of the strength of this extra force in terms of the baryonic mass, Newton’s constant and the Hubble acceleration scale a0 = cH0, and provide evidence for the fact that this additional ‘dark gravity force’ explains the observed phenomena in galaxies and clusters currently attributed to dark matter.
The cost of acquiring information by natural selectionCarl Bergstrom
This is a short talk that I gave at the Banff International Research Station workshop on Modeling and Theory in Population Biology. The idea is to try to understand how the burden of natural selection relates to the amount of information that selection puts into the genome.
It's based on the first part of this research paper:
The cost of information acquisition by natural selection
Ryan Seamus McGee, Olivia Kosterlitz, Artem Kaznatcheev, Benjamin Kerr, Carl T. Bergstrom
bioRxiv 2022.07.02.498577; doi: https://doi.org/10.1101/2022.07.02.498577
Authoring a personal GPT for your research and practice: How we created the Q...Leonel Morgado
Thematic analysis in qualitative research is a time-consuming and systematic task, typically done using teams. Team members must ground their activities on common understandings of the major concepts underlying the thematic analysis, and define criteria for its development. However, conceptual misunderstandings, equivocations, and lack of adherence to criteria are challenges to the quality and speed of this process. Given the distributed and uncertain nature of this process, we wondered if the tasks in thematic analysis could be supported by readily available artificial intelligence chatbots. Our early efforts point to potential benefits: not just saving time in the coding process but better adherence to criteria and grounding, by increasing triangulation between humans and artificial intelligence. This tutorial will provide a description and demonstration of the process we followed, as two academic researchers, to develop a custom ChatGPT to assist with qualitative coding in the thematic data analysis process of immersive learning accounts in a survey of the academic literature: QUAL-E Immersive Learning Thematic Analysis Helper. In the hands-on time, participants will try out QUAL-E and develop their ideas for their own qualitative coding ChatGPT. Participants that have the paid ChatGPT Plus subscription can create a draft of their assistants. The organizers will provide course materials and slide deck that participants will be able to utilize to continue development of their custom GPT. The paid subscription to ChatGPT Plus is not required to participate in this workshop, just for trying out personal GPTs during it.
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...Advanced-Concepts-Team
Presentation in the Science Coffee of the Advanced Concepts Team of the European Space Agency on the 07.06.2024.
Speaker: Diego Blas (IFAE/ICREA)
Title: Gravitational wave detection with orbital motion of Moon and artificial
Abstract:
In this talk I will describe some recent ideas to find gravitational waves from supermassive black holes or of primordial origin by studying their secular effect on the orbital motion of the Moon or satellites that are laser ranged.
Product Design Trends in 2024 | Teenage EngineeringsPixeldarts
The realm of product design is a constantly changing environment where technology and style intersect. Every year introduces fresh challenges and exciting trends that mold the future of this captivating art form. In this piece, we delve into the significant trends set to influence the look and functionality of product design in the year 2024.
How Race, Age and Gender Shape Attitudes Towards Mental HealthThinkNow
Mental health has been in the news quite a bit lately. Dozens of U.S. states are currently suing Meta for contributing to the youth mental health crisis by inserting addictive features into their products, while the U.S. Surgeon General is touring the nation to bring awareness to the growing epidemic of loneliness and isolation. The country has endured periods of low national morale, such as in the 1970s when high inflation and the energy crisis worsened public sentiment following the Vietnam War. The current mood, however, feels different. Gallup recently reported that national mental health is at an all-time low, with few bright spots to lift spirits.
To better understand how Americans are feeling and their attitudes towards mental health in general, ThinkNow conducted a nationally representative quantitative survey of 1,500 respondents and found some interesting differences among ethnic, age and gender groups.
Technology
For example, 52% agree that technology and social media have a negative impact on mental health, but when broken out by race, 61% of Whites felt technology had a negative effect, and only 48% of Hispanics thought it did.
While technology has helped us keep in touch with friends and family in faraway places, it appears to have degraded our ability to connect in person. Staying connected online is a double-edged sword since the same news feed that brings us pictures of the grandkids and fluffy kittens also feeds us news about the wars in Israel and Ukraine, the dysfunction in Washington, the latest mass shooting and the climate crisis.
Hispanics may have a built-in defense against the isolation technology breeds, owing to their large, multigenerational households, strong social support systems, and tendency to use social media to stay connected with relatives abroad.
Age and Gender
When asked how individuals rate their mental health, men rate it higher than women by 11 percentage points, and Baby Boomers rank it highest at 83%, saying it’s good or excellent vs. 57% of Gen Z saying the same.
Gen Z spends the most amount of time on social media, so the notion that social media negatively affects mental health appears to be correlated. Unfortunately, Gen Z is also the generation that’s least comfortable discussing mental health concerns with healthcare professionals. Only 40% of them state they’re comfortable discussing their issues with a professional compared to 60% of Millennials and 65% of Boomers.
Race Affects Attitudes
As seen in previous research conducted by ThinkNow, Asian Americans lag other groups when it comes to awareness of mental health issues. Twenty-four percent of Asian Americans believe that having a mental health issue is a sign of weakness compared to the 16% average for all groups. Asians are also considerably less likely to be aware of mental health services in their communities (42% vs. 55%) and most likely to seek out information on social media (51% vs. 35%).
AI Trends in Creative Operations 2024 by Artwork Flow.pdfmarketingartwork
Creative operations teams expect increased AI use in 2024. Currently, over half of tasks are not AI-enabled, but this is expected to decrease in the coming year. ChatGPT is the most popular AI tool currently. Business leaders are more actively exploring AI benefits than individual contributors. Most respondents do not believe AI will impact workforce size in 2024. However, some inhibitions still exist around AI accuracy and lack of understanding. Creatives primarily want to use AI to save time on mundane tasks and boost productivity.
Organizational culture includes values, norms, systems, symbols, language, assumptions, beliefs, and habits that influence employee behaviors and how people interpret those behaviors. It is important because culture can help or hinder a company's success. Some key aspects of Netflix's culture that help it achieve results include hiring smartly so every position has stars, focusing on attitude over just aptitude, and having a strict policy against peacocks, whiners, and jerks.
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2. the distribution of the cross section-averaged swirl ratio. The
tangential velocity profiles at the cross sections are highly nonlinear,
and the rigid body rotation assumption is less admissible. Ceper [17]
studied the combustion and emission performance characteristics of
different percentage ratios of hydrogen–methane gas mixtures
experimentally and numerically. 100% CH4, 10% H2-90% CH4, 20%
H2-80% CH4 and 30% H2-70% CH4 gas mixtures were investigated at
2000 rpm engine speeds and excess air ratios on a model, which is
developed based on real engine diameters used in her numerical
study. In-cylinder pressure and temperature variations were given
based on crank angles. She found that numerical study were found
well-matched with experimental results.
The main purpose of the present study is to investigate the heat
transfer and fluid flow in a pent-roof type combustion chamber and
the effects of the combustion chamber shape on the flow during
intake stroke. The engine studied in this paper is a single-cylinder
spark-ignition gasoline engine with one intake port of the cylinder.
The study shows how flow acts inside of whole intake cycle and it
clarifies some places in which designer should consider some
geometrical innovations.
2. Definition of considered model
Fig. 1 (a) shows three-dimensional model of the combustion
chamber. This is drawn using Solid Works. It is a pent-roof type of
combustion chamber. In this study, flow and heat transfer is modeled
as two-dimensional. Thus, physical model is plotted in Fig. 1 (b) It
consists of real geometries which are used in two-dimensional
studies with their geometric values. Flow domains are created and
the models are meshed in the same code [18] as illustrated in Fig. 1
(c). The engine is simulated a four stroke engine with pent-roof
combustion chamber, and the engine parameters are listed in Table 1.
The piston has flat surface in these figures. As indicated from the
figures that the combustion chamber likes rectangular cavity
depends on piston position except roof of it.
3. Governing equations
Calculation of the temperature and flow field in a combustion
chamber of internal combustion engine requires obtaining the
solution of the governing equations. Compressible, unsteady and
turbulent in-cylinder flow can be described by differential equations
of continuity, momentum, energy, turbulence kinetic energy and its
dissipation rate. Radiation mode of heat transfer is neglected
according to other modes of heat transfer. Buoyancy forces are also
neglected and heat transfer regime is accepted as forced convection.
The mass conservation equation can be written as follows:
∂ρ
∂t
+ ∇⋅ ρVð Þ = 0 ð1Þ
Momentum equations can be written in two directions as:
∂ ρuð Þ
∂t
+
∂ ρu2
∂x
+
∂ ρuvð Þ
∂y
= −
∂p
∂x
+
∂
∂x
λ
∂v
∂x
+
∂u
∂y
V + 2μ
∂u
∂x
+
∂
∂y
μ
∂v
∂x
+
∂u
∂y
ð2Þ
∂ ρvð Þ
∂t
+
∂ ρv
2
∂y
+
∂ ρuvð Þ
∂x
= −
∂p
∂y
+
∂
∂x
μ
∂v
∂x
+
∂u
∂y
+
∂
∂y
λ∇V + 2μ
∂v
∂x
ð3Þ
Energy equation
∂ ρeð Þ
∂t
+ ∇ ρeVð Þ =
∂
∂x
k
∂T
∂x
+
∂
∂y
k
∂T
∂y
ð4Þ
The turbulence kinetic energy, k, and its rate of dissipation, ε, are
obtained from the following transport equations:
ρ
Dk
Dt
=
∂
∂xi
μeff +
μt
σk
∂k
∂xi
+ Gk + Gb−ρε−YM ð5Þ
ρ
De
Dt
=
∂
∂xi
μeff +
μt
σε
∂ε
∂xi
+ Cε1
ε
k
Gk + Cε3Gbð Þ−Cε2ρ
ε2
k
: ð6Þ
There are numerous alternative turbulence modeling approaches of
varying degree of complexity, but in this work, k–ε turbulence model
was used to forecast the flow in the cylinder of an incompressible fluid
[14]. In k–ε model, the turbulent or eddy viscosity concept, and
calculation of turbulent viscosity μt according to Prandtl–Kolmogorov
relation is given as
μt = ρCμ
k
2
ε
ð7Þ
Nomenclature
e internal energy per unit mass, J/kg
Gb the generation of turbulence kinetic energy due to
buoyancy
Gk represents the generation of turbulence kinetic energy
due to the mean velocity gradients
k thermal conductivity, W/mK
n engine speed, rpm
p pressure, Pa
T temperature, K
t time, s
u, v, w velocity magnitudes in direction −x,−y,−z, m/s
V volume, m3
Vc combustion chamber volume, m3
Greek symbols
θ crank angle
turbulent dissipation rate, m2
/s3
μ dynamic viscosity, Pa/s
μt turbulence viscosity
ρ fluid density, kg/m3
σk the turbulent Prandtl numbers for k
σ the turbulent Prandtl numbers for
1367Y. Varol et al. / International Communications in Heat and Mass Transfer 37 (2010) 1366–1375
3. C1, C2 and C3 are model constant. These coefficients are,
C1 = 1:44; C2 = 1:92; Cμ = 0:09; μk = 1:0; σ = 1:3
Total effective viscosity of the flow is then, given by the
combination of the turbulent viscosity and laminar viscosity as
μeff = μt + μ ð8Þ
3.1. Boundary conditions
As indicated above that only time dependent intake valve situation
is presented in this work. The inlet boundary conditions were
obtained from the calculated instantaneous mass flow rate. This can
be done due to acceptation of the incompressibility. Also, no-slip
boundary conditions were applied for all velocities at walls. The fluid
velocity at the moving piston surface is equal to the instantaneous
piston velocity. Near wall region is treated by using well known wall
functions, based on the assumption of logarithmic velocity
Fig. 1. a) Solid model from different view, b) Physical models, c) Grid distribution.
1368 Y. Varol et al. / International Communications in Heat and Mass Transfer 37 (2010) 1366–1375
4. distribution [19]. Boundary conditions for the considered physical
model (Fig. 1) are given as
Inlet temperature, Tinlet =303 K
Side temperature of combustion chamber, Tside =493 K
Temperature of piston head, Tpiston =493 K
Inlet velocities are V=14, 33 and 54 m/s for n=1000, 3000 and
5000 rpm, respectively.
Velocities at side of cylinder, u=0, v=0
Velocities at piston surface, u=0, v=vpiston
4. Numerical solution
The flow characteristics of engine models are considered as two-
dimensional. Dynamic models were investigated numerically by
means of FLUENT commercial code [18]. It is a well known
Computational Fluid Dynamic program that it is the science of
predicting fluid flow, heat transfer, mass transfer, chemical reactions,
and related phenomena by solving governing equations. This
program uses finite volume method in order to solve Navier-stokes
and energy equations and it is widely used in the field of internal
combustion engine design. The finite volume method can accom-
modate any type of grid. Thus, it is suitable for complex geometries,
like present study. The standard k–ε turbulence model was used as
engine model. The CFD code is based on the pressure-correction and
uses the SIMPLE algorithm of Patankar [20]. The first order upwind
difference scheme (UDS) is used to discretize the momentum, energy
and turbulence equations. The dynamic grid approach is used to treat
the moving piston in the computational area. In other words, the grid
generation approach was used to treat the moving piston as a moving
solid body in the computational domain without generating
completely new grids at each crank angle step [21]. Piston moves
towards to the bottom dead center (BDC). The calculations are
started with a crank angle of top dead center (TDC) and finished at
30° after bottom dead center (aBDC) in the compression stroke
for a different engine speed as 1000, 3000 and 5000 rpm. The model
structure is hybrid grid and to setup boundary condition for moving
piston. Total number of computational cells was used about 50,000 at
BDC and 10,000 cells at TDC. A typical grid distribution is shown in
Fig. 2.
5. Results and discussion
A computational study has been performed in this work for
different crank angles and revolution of pent-roof combustion
Fig. 2. Velocity vectors for different crank angle at n=3000 rpm, a) θ=30°, b) θ=60°, c) θ=90°, d) θ=120°, e) θ=150°, f) θ=180°, g) θ=210°.
Table 1
Engine geometry and parameters.
Bore/mm 82
Stroke/mm 90
Intake valve angle/deg 22
Crank period/deg 720
Engine speed/rpm 1000, 3000 and 5000
1369Y. Varol et al. / International Communications in Heat and Mass Transfer 37 (2010) 1366–1375
5. chamber. In this part of the study, the results are present with velocity
vectors, pressure contours, velocity profiles and temperature con-
tours. As indicated above that standard k–ε model was carried out for
all two-dimensional model.
Fig. 2 presents the velocity vectors for different crank angle and
n=3000 rpm. Pent-roof cylinder model sweep out inside of cylinder
better than other models as indicated in literature [9]. There is no
swirl effect in this type. A jet effect is occurred near the valve gap
region due to very small area of this region of internal combustion
engines. Thus, the maximum velocity is formed at this part. For two-
dimensional model, the jet effect is seen at two sides of the valve and
it decreases as valve is getting down. Due to oval shaped of the roof of
combustion chamber, the flow distribution is not symmetric. The flow
generates stronger jet in both sides of the valve. At the beginning of
the intake stroke, the flow produced by the moving piston away from
the chamber head towards bottom dead center impinges to the piston
top surface at lower velocity according to inlet velocity. The flow is
probably laminar. Inlet flow impinges to left and right vertical walls
and two circulation cells were formed in clockwise and counterclock-
wise directions. It is an interesting result that the flow inlets from
right side of the valve become dominant with increasing of crank
angle. And, multiple cells were formed at the top oval shaped region
}
Fig. 2 (continued).
1370 Y. Varol et al. / International Communications in Heat and Mass Transfer 37 (2010) 1366–1375
6. for higher crank angle. Impinging flow onto piston moves toward to
valve and again impinges to the valve. This is a characteristic flow
motion of a gas engines. For higher crank angles, the combustion
chamber looks a cavity. Please note that in case of crank angle of 210°,
the piston moves toward to TDC. Fig. 3 display the effects of revolution
for the same crank angle. Revolution number is not an effective
parameter on velocity direction. But boundary layer becomes thinness
on top of piston at higher revolution.
Fig. 4 illustrate the isotherms of the same case of Fig. 2. It is noticed
that temperature boundary conditions for combustion chamber was
Fig. 3. Comparison of velocity vectors for different revolutions at θ=90°, a) n=1000 rpm, b) n=5000 rpm.
Fig. 4. Isotherms for different crank angle at n=3000 rpm, a) θ=30°, b) θ=60°, c) θ=90°, d) θ=120°, e) θ=150°, f) θ=180°, g) θ=210°.
1371Y. Varol et al. / International Communications in Heat and Mass Transfer 37 (2010) 1366–1375
7. measured from an exact engine and its temperature of cooling water.
Thus, constant temperature boundary conditions were kept as 493 K.
It is clearly seen from the isotherms that the temperature of fluid
inside the combustion chamber increases with increasing of crank
angle. Temperature rises at the cross section of rotated flow as given
in Fig. 2. It is an interesting result that temperature of two rotating
flows is almost equal to each other. Nevertheless, crank angle is
effective parameters on this value. Fig. 5 compare the effects of
revolution on temperature distribution. It is seen that revolution is an
effective parameter on temperature distribution. Temperature of
rotating fluid decreases with increasing of revolution number. The
temperature values are almost equal for both main eddies. The
strength of plume-like temperature distribution at the intersection of
clockwise and counterclockwise rotating fluid becomes higher for
n=5000 rpm. Pressure distribution inside the combustion chamber
is presented in Fig. 6 (a) to (d) for n=3000 rpm. It is an expected
result that low pressure is formed around the valve. Pressure values
are decrease with increasing of value of revolution. The sharp corner
disturbs the fluid and they may enhance the effectiveness of the
combustion. Finally, static pressure, velocity magnitude and tem-
perature values are illustrated in Fig. 7 (a), (b) and (c), respectively.
All results were presented for θ=90°. The profiles are taken at
y=Vc/2 (Fig. 1 (b)) and along the x-axis. Fig. 7 (a) showed that the
pressure is almost constant for n=1000 rpm. A sinusoidal variation
}
Fig. 4 (continued).
1372 Y. Varol et al. / International Communications in Heat and Mass Transfer 37 (2010) 1366–1375
8. was obtained with increasing of revolution and pressure is also
increased. It is an interesting result that the pressure is lower at the
right-half section of the cylinder. The velocity magnitude is obtained
symmetrically according to middle x-axis as seen in Fig. 7 (b). The
value of revolution enhances the velocity of the fluid, as expected.
Temperature distribution is also obtained symmetrically and tem-
Fig. 5. Comparison of isotherms for different revolutions at θ=90°, a) n=1000 rpm, b) n=5000 rpm.
Fig. 6. Pressure contours for different crank angle at n=3000 rpm a) θ=30°, b) θ=60, c) θ=180°, d) θ=210°.
1373Y. Varol et al. / International Communications in Heat and Mass Transfer 37 (2010) 1366–1375
9. Fig. 7. a) Static pressure, b) Velocity, c) Temperature for different revolution at θ=90°.
1374 Y. Varol et al. / International Communications in Heat and Mass Transfer 37 (2010) 1366–1375
10. perature is decreased with increasing of revolution due short intake
stroke.
6. Conclusions
A numerical work has been done in this study to see the how shape
and revolution of engine affects the flow and temperature fields. The
main conclusions drawn from the results of the present study may be
listed as follows:
• Two circulation cells were formed at different rotation directions for
all cases. This is a typical property of a gasoline engine. Flow
distribution inside the cylinder is almost symmetric for low values
of crank angles. But the flow at inclined side of the chamber
becomes dominant with increasing of crank angles.
• The pent-roof type of combustion chamber can be a control parameter
for heat and fluid flow.
• Temperature of the fluid increases with increasing of crank angle but
decreases with revolution.
• It is observed that the Reynolds averaged turbulence model k–ε gives
acceptable results for heat and fluid flow in pent-roof type combustion
chambers.
Acknowledgements
Authors thank Firat University Scientific and research fund for
their valuable financial support with a project number 1874.
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