Selective optical manipulation of particles in acoustic levitation

International audienceAcoustic Radiation Force (ARF) is commonly used to create stable large-scale aggregates of particles in levitation (so-called "acoustic levitation) in a micro cavity. We show in the following work that this well-known and well-controlled aggre-gation process can be reversed without contact or external flow if the aggregated particles are enlightened with the proper optical wavelength. This coupled optics and acoustics effect has been observed with various kinds of particles and different optic wavelengths, showing high reproducibility. The phenomenon is studied using fluorescent micro-metric polystyrene particles without flow, and the effects of acoustic energy and illumination power have been quantitatively assessed. Since it is a tag free phenomenon, does not need high energies to happen and that it works with biological objects such as algae, red blood cells and bacteria, it may pave the way to a broad range of applications

Acoustic propulsion of metallic nano-cylinders: contribution of the local vertical acceleration from micro to hyper gravity

International audienc

Finite Element Method for Evaluating Rising and Slip of Column–Base Plate for Usual Connections

Предложена конечноэлементная методика расчета деформирования и относительного проскальзывания креплений стальной колонны кжелезобетонному основанию. Рассмотрены два случая крепления: пластина приваривается к торцу колонны и крепится двумя или четырьмя анкерными болтами к железобетонному основанию. В конечноэлементной модели с использованием модифицированного метода Лагранжа учитывается растрескивание бетонного основания и эффекты трения. Деформирование бетонного основания описывается с помощью упругопластической модели сжатия материала. По результатам расчетов построены диаграммы перемещений элементов крепления.Запропоновано скінченноелементну методику розрахунку деформування і відносного проковзування кріплень стальної колони до залізобетонної основи. Розглянуто два випадки кріплення: пластина приварюється до торця колони і кріпиться двома або чотирма анкерними болтами до залізобетонної основи. У скінченноелементній моделі з використанням модифікованого методу Лагранжа враховується розтріскування бетонної основи й ефекти тертя. Деформування бетонної основи описується за допомогоюпружно-пластичної моделі стиску матеріалу. За результатами розрахунків побудовано діаграми переміщень елементів кріплення

Stability Analysis of Optimal Velocity Model for Traffic and Granular Flow under Open Boundary Condition

We analyzed the stability of the uniform flow solution in the optimal velocity model for traffic and granular flow under the open boundary condition. It was demonstrated that, even within the linearly unstable region, there is a parameter region where the uniform solution is stable against a localized perturbation. We also found an oscillatory solution in the linearly unstable region and its period is not commensurate with the periodicity of the car index space. The oscillatory solution has some features in common with the synchronized flow observed in real traffic.Comment: 4 pages, 6 figures. Typos removed. To appear in J. Phys. Soc. Jp

The Mood of the Silver Economy: A Data Science Analysis of the Mood States of Older Adults and the Implications on their Wellbeing

For the first time in the history of humanity, the number of people over 65 surpassed those under 5 in 2018. Undoubtedly, older people will play a significant role in the future of the economy and society in general, and technological innovation will be indispensable to support them. Thus, we were interested in learning how home automation could enable older people to live independently for longer. To better understand this, we held focus groups with UK senior citizens in 2021, and we analyzed the data derived from them from the perspective of affective computing. We have trained a machine learning classifier capable of distinguishing moods commonly associated with older adults. We have identified depression, sadness and anger as the most prominent mood states conveyed in our focus groups. Our practical insights can aid the design of strategic choices concerning the wellbeing of the ageing population

Slow dynamics and aging of a confined granular flow

We present experimental results on slow flow properties of a granular assembly confined in a vertical column and driven upwards at a constant velocity V. For monodisperse assemblies this study evidences at low velocities ($1<V<100 \mu m/s$) a stiffening behaviour i.e. the stress necessary to obtain a steady sate velocity increases roughly logarithmically with velocity. On the other hand, at very low driving velocity ($V<1 \mu m/s$), we evidence a discontinuous and hysteretic transition to a stick-slip regime characterized by a strong divergence of the maximal blockage force when the velocity goes to zero. We show that all this phenomenology is strongly influenced by surrounding humidity. We also present a tentative to establish a link between the granular rheology and the solid friction forces between the wall and the grains. We base our discussions on a simple theoretical model and independent grain/wall tribology measurements. We also use finite elements numerical simulations to confront experimental results to isotropic elasticity. A second system made of polydisperse assemblies of glass beads is investigated. We emphasize the onset of a new dynamical behavior, i.e. the large distribution of blockage forces evidenced in the stick-slip regime

Concentration of apricot juice using complex membrane technology

In this study, pressed apricot (Prunus armeniaca L.) juice was concentrated using complex membrane technology with different module combinations: UF-RO-OD, UF-RO-MD, UF-NF-OD and UF-NF-MD. In case of the best combination a cross-flow polyethylene ultrafiltration membrane (UF) was applied for clarification, after which preconcentration was done using reverse osmosis (RO) with a polyamide membrane, and the final concentration was completed by osmotic distillation (OD) using a polypropylene module. The UF-RO-OD procedure resulted in a final concentrate with a 65-70 °Brix dry solid content and an excellent quality juice with high polyphenol content and high antioxidant capacity.Nanofiltration (NF) and membrane distillation (MD) were not proper economic solutions.The influence of certain operation parameters was examined experimentally. Temperatures of UF and RO were: 25, 30, and 35 °C, and of OD 25 °C. Recycle flow rates were: UF: 1, 1.5, and 2 m3 h−1; RO: 200, 400, and 600 l h−1; OD: 20, 30 and 40 l h−1. The flow rates in the module were expressed by the Reynolds number, as well. Based on preliminary experiments, the transmembrane pressures of UF and RO filtration were 4 bar and 50 bar, respectively. Each experimental run was performed three times. The following optimal operation parameters provided the lowest total cost: UF: 35 °C, 2 m3 h−1, 4 bar; RO: 35 °C, 600 l h−1, 50 bar; OD: 20, 30 and 40 l h−1; temperature 25 °C.In addition, experiments were performed for apricot juice concentration by evaporation, which technique is widely applied in the industry using vacuum and low temperature.For description the UF filtration, a dynamic model and regression by SPSS 14.0 statistics software were applied

Acrylamide formation and quality properties of chitosan based batter formulations

[EN] The potential of chitosan to mitigate acrylamide formation has been already demonstrated. The two main objectives of this study were: 1) to select the most adequate degree of deacetylation (DD) and molecular weight (Mw) of chitosan based on acrylamide mitigation criteria and 2) to evaluate the influence of including chitosan in batter formulations on some important technological parameters of raw batters (flow behavior and water retention capacity) and on some quality properties of fried batters (oil uptake, color and texture). Results in model systems showed that chitosans with higher deacetylation degree (86.5 and 92.8%) achieved a decrease of acrylamide between 44 and 81%, depending on reaction time, compared to the control (without chitosan). Furthermore, acid hydrolysis process of chitosan was found to negatively affect its inhibitory effect on acrylamide formation independently of the molecular weight. Raw chitosan based batter formulations presented higher consistency and water retention capacity than the control; chitosan addition to batters reduced the hardening of the fried samples during the post-frying cooling period. No significant differences in water loss were observed between batters with or without added chitosan; however, chitosan-batter formulations showed lower oil uptake during frying as compared to control samples.The authors thank the gs1:Universitat Politecnica de Valencia for the PhD scholarship given to Mariola Sansano Tomas.Sansano Tomás, M.; Castelló Gómez, ML.; Heredia Gutiérrez, AB.; Andrés Grau, AM. (2016). Acrylamide formation and quality properties of chitosan based batter formulations. Food Hydrocolloids. 66:1-7. doi:10.1016/j.foodhyd.2016.10.019S176