Suspensions of finite-size neutrally-buoyant spheres in turbulent duct flow

We study the turbulent square duct flow of dense suspensions of neutrally-buoyant spherical particles. Direct numerical simulations (DNS) are performed in the range of volume fractions $\phi=0-0.2$, using the immersed boundary method (IBM) to account for the dispersed phase. Based on the hydraulic diameter a Reynolds number of $5600$ is considered. We report flow features and particle statistics specific to this geometry, and compare the results to the case of two-dimensional channel flows. In particular, we observe that for $\phi=0.05$ and $0.1$, particles preferentially accumulate on the corner bisectors, close to the duct corners as also observed for laminar square duct flows of same duct-to-particle size ratios. At the highest volume fraction, particles preferentially accumulate in the core region. For channel flows, in the absence of lateral confinement particles are found instead to be uniformily distributed across the channel. We also observe that the intensity of the cross-stream secondary flows increases (with respect to the unladen case) with the volume fraction up to $\phi=0.1$, as a consequence of the high concentration of particles along the corner bisector. For $\phi=0.2$ the turbulence activity is strongly reduced and the intensity of the secondary flows reduces below that of the unladen case. The friction Reynolds number increases with $\phi$ in dilute conditions, as observed for channel flows. However, for $\phi=0.2$ the mean friction Reynolds number decreases below the value for $\phi=0.1$.Comment: Submitted to Journal of Fluid Mechanic

Probing Membrane Viscosity and Interleaflet Friction of Supported Lipid Bilayers by Tracking Electrostatically Adsorbed, Nano-Sized Vesicles

Particle tracking is used to measure the diffusional motion of nanosized (≈100 nm), lipid vesicles that are electrostatically adsorbed onto a solid supported lipid bilayer. It is found that the motion of membrane-adhering vesicles is Brownian and depends inversely on the vesicle size, but is insensitive to the vesicle surface charge. The measured diffusivity agrees well with the Evans–Sackmann model for the diffusion of inclusions in supported, fluidic membranes. The agreement implies that the vesicle motion is coupled to that of a nanoscopic lipid cluster in the upper leaflet, which slides over the lower leaflet. The diffusivity of membrane-adhering vesicles is therefore predominantly governed by the interleaflet friction coefficient, while the diffusivity of single lipids is mainly governed by the membrane viscosity. Combined with fluorescence recovery after photobleaching analysis, the interleaflet friction coefficient and the membrane viscosity are determined by applying the Evans–Sackmann model to the measured diffusivity of membrane adhering vesicles and that of supported membrane lipids. This approach provides an alternative to existing methods for measuring the interleaflet friction coefficient and the membrane viscosity

Studying the Effect of Tunnel Depth Variation on the Specific Energy of TBM, Case Study: Karaj–Tehran (Iran) Water Conveyance Tunnel

The tunnel-boring machine (TBM) is a common piece of equipment used in tunneling projects. For planning a mechanical excavation project, prediction of TBM performance and the specification of design elements such as required forces are critical. The specific energy of excavation (SE), i.e. drilling energy consumption per unit volume of rock mass, is a crucial parameter for performance prediction of a TBM. In this study, the effect of variation of tunnel depth on SE by considering the post-failure behavior of rock mass was investigated. Several new relations between SE and tunnel depth are proposed according to the statistical analysis obtained from Karaj–Tehran Water Conveyance Tunnel real data. The results showed that there is a direct relation between both parameters and .A polynomial equations are proposed as the best expression of the correlation between these parameters

Wyzwania i korzyści płynące z teleterapii i wykorzystania świata cyfrowego w praktyce arteterapeutycznej : przegląd integracyjny

Biorąc pod uwagę, że współczesne technologie umożliwiają prowadzenie psychoterapii na odległość, ważna dla jej praktyków staje się dyskusja na temat wad i zalet wykorzystania do tego celu cyberprzestrzeni. Celem niniejszego artykułu jest przedstawienie negatywnych i pozytywnych cech arteterapii w formie online. Tekst bazuje na integracyjnym przeglądzie recenzowanej literatury na temat wykorzystania technologii cyfrowych w psychoterapii i terapii sztuką. Uwzględniono nie tylko badania, które przedstawiały wyniki empiryczne, ale także badania obserwacyjne i jakościowe, w których oceniano skuteczność e-terapii i arteterapii online. Wyniki badań wskazują na wysoką akceptację klientów i terapeutów oraz pozytywne aspekty związane z tą metodą prowadzenia psychoterapii, takie jak przyjemność katartyczna i multimodalne środowisko ekspresji. Niemniej jednak, terapeuci sztuki chcący prowadzić psychoterapię w trybie online napotykają na szereg wyzwań, w tym brak walorów dotykowych oraz trudności w zarządzaniu i radzeniu sobie z sytuacjami kryzysowymi na odległość. Mimo, że cyberprzestrzeń zapewnia wolność ekspresji dla klientów i usług terapii sztuką na całym świecie, potrzeba biegłości technologicznej ogranicza dostęp do terapii. Dodatkowo, istnieją obawy etyczne, polegające na zmniejszonym zaufaniu w relacji terapeutycznej i utracie kontroli nad prowadzeniem sesji psychoterapii kryzysowej w formie online.Objective: Considering that the capabilities of technology to conduct psychotherapy remotely are expanding, practitioners could benefit from discussions on the pros and cons of using cyberspace in art therapy. Thus, the aim of this integrative review is to present and contrast the negative and positive features of online art therapy. Methods: An integrative review of peer-reviewed literature on the use of digital technology in psychotherapy and art therapy was conducted. Not only studies that presented empirical outcomes were included but also observational and qualitative studies in which the effectiveness of e-therapy and online art therapy has been evaluated were considered. Results: The literature review indicates high clients’ and therapists’ acceptance and multiple positive aspects of this method of psychotherapy such as cathartic pleasure and multimodal expression environment. Nevertheless, art therapists wishing to conduct psychotherapy online face some challenges, including lack of tactile qualities and difficulty in managing and handling crisis situations at a distance. Conclusion: Although cyberspace provides the freedom of expression for clients and art therapy services are available around the world, the need of technology proficiency limits the access to this type of therapy. Additionally, ethical concerns include reduced trust in a therapeutic relationship and losing the control over conducting online psychotherapy sessions in crisis. However, reducing clients’ resistance to online therapy can become possible by using convenient technologies. Moreover, participants of online art therapy can be more autonomous, despite the lack of tangible physical engagement with online media that leads clients to disconnecting from social interaction

Results from a Psychology OER pilot program: faculty and student perceptions, cost savings, and academic outcomes

This case study describes the library’s experience of collaborating with an undergraduate Psychology Department at Touro College to integrate open textbooks into their program. We discuss the pedagogical changes as well as explore the impact of Open Educational Resources (OER) on students’ savings, their academic outcomes and perceptions of OER. Furthermore, we highlight the successes and shortcomings in having the library as a central OER partner. To measure the results, we surveyed students and conducted a faculty survey and a focus group, in addition to analyzing the students’ final grades. This pilot program delivered strong results. The students’ perception was very positive, and faculty’s opinions on the textbooks used were mixed. Some professors felt that the textbook lacked important content, but because of its openness, they added their own content to the book. Students enrolled in OER courses performed better than those enrolled in the same courses using a commercial textbook

Studying the Effect of Tunnel Depth Variation on the Specific Energy of TBM, Case Study: KarajâTehran (Iran) Water Conveyance Tunnel

The tunnel-boring machine (TBM) is a common piece of equipment used in tunneling projects. For planning a mechanical excavation project, prediction of TBM performance and the specification of design elements such as required forces are critical. The specific energy of excavation (SE), i.e. drilling energy consumption per unit volume of rock mass, is a crucial parameter for performance prediction of a TBM. In this study, the effect of variation of tunnel depth on SE by considering the post-failure behavior of rock mass was investigated. Several new relations between SE and tunnel depth are proposed according to the statistical analysis obtained from Karaj"“Tehran Water Conveyance Tunnel real data. The results showed that there is a direct relation between both parameters and .A polynomial equations are proposed as the best expression of the correlation between these parameters

Investigating Carbon Dynamics of a Young Temperate Coniferous Forest Using Long-Term Eddy Covariance Flux Observations

Plantation and managed forests are major sink of atmospheric CO2 in North America and across the world. If properly managed, these forests may help to offset anthropogenic greenhouse gas emissions to mitigate climate change. This study investigated the impacts of climate variability, extreme weather events, and disturbance (thinning) on the growth and carbon (C) exchanges of a young temperate coniferous plantation forest (48-year-old white pine (Pinus strobus)) in the Great Lakes region in Canada using long-term eddy covariance flux observations. CO2 fluxes, as well as meteorological and soil variables were continuously measured from 2008 to 2021 (14 years) to estimate net ecosystem productivity (NEP), ecosystem respiration (RE), and gross ecosystem productivity (GEP). Soil respiration (Rs) was also measured using automatic soil chambers from 2017 to 2019. Selective thinning was conducted first time in this stand in January 2021 to remove approximately 1/3 of the basal area. Study results showed that climate conditions in the early growing season, from late May to mid-July, determined the overall strength of C uptake in any given year. However, above-average temperature and precipitation in the late growing season significantly reduced NEP and even in some cases, transformed the forest into a net C source for short periods due to large pulses of RE. Mean annual GEP, RE and NEP values were 1660 ±199, 1087 ±96 and 592 ±169 g C m-2 yr-1, respectively, from 2008 to 2021. Thinning did not significantly impact the C uptake of the forest as the stand remained a net C sink with an annual NEP of 648 g C m-2 yr-1 in 2021. Changes in annual GEP, RE and NEP in 2021 remained within the range of interannual variability over the study period. Overall, Rs accounted for roughly 89% of the annual RE in this stand. A complete understanding of the response of forest C dynamics to climate variability and thinning in young plantation forests is critical to guiding future forest management efforts for enhancing the growth and C uptake of these forest plantations to maximize their potential in support of providing nature-based climate solutions.ThesisMaster of Science (MSc