ΜΕΤΡΗΣΕΙΣ ΤΥΡΒΩΔΟΥΣ ΡΟΗΣ ΣΕ ΑΝΟΙΚΤΟ ΑΓΩΓΟ ΔΙΑΠΕΡΑΤΟΥ ΠΥΘΜΕΝΑ ΜΕ ΑΝΕΜΟΜΕΤΡΙΑ ΘΕΡΜΟΥ ΦΙΛΜ

Στην  εργασία  αυτή  διερευνάται  εργαστηριακά  η  τυρβώδης  ροή  σε ανοικτό  αγωγό  με  διαπερατό  πυθμένα  με  τη  χρήση  ανεμομετρίας  θερμού  φιλμ (hot-film). Ο διαπερατός πυθμένας  προσομοιώνεται με πορώδη φίλτρα πορώδους ε  ίσου με 0.70  και 0.91.  Το  σχετικό  πάχος  πορώδους s΄/h (s΄=πάχος  πορώδους, h=συνολικό βάθος ροής πάνω και μέσα από το πορώδες στρώμα) μεταβάλλεται από 0.375 έως 0.5. Μετρήσεις  της  παροχής,  μέσης  ταχύτητας  και  τυρβωδών  μεγεθών (ένταση  τύρβης, τάσεις Reynolds) φανερώνουν την επίδραση των παραπάνω μεγεθών (ε και s΄/h)  στα χαρακτηριστικά της ροής και στην παροχετευτική ικανότητα του αγωγού.Turbulent flow in an open channel with a permeable bed is investigated experimentally with the use of hot-film anemometry. The permeable bed is simulated with porous filters of porosity  ε equal to 0.70 and 0.91. The relative thickness of the porous layer s΄/h (s΄=porous thickness, h=total flow depth over and through porous layer) varies between 0.375 and 0.5. Measurements of discharge, mean velocity and turbulence characteristics (turbulence intensity, Reynolds stresses) indicate the effect of ε and s΄/h on the flow characteristics and the discharge capacity of the channel.

The use of mesenchymal stem cells for cartilage repair and regeneration: a systematic review.

BACKGROUND: The management of articular cartilage defects presents many clinical challenges due to its avascular, aneural and alymphatic nature. Bone marrow stimulation techniques, such as microfracture, are the most frequently used method in clinical practice however the resulting mixed fibrocartilage tissue which is inferior to native hyaline cartilage. Other methods have shown promise but are far from perfect. There is an unmet need and growing interest in regenerative medicine and tissue engineering to improve the outcome for patients requiring cartilage repair. Many published reviews on cartilage repair only list human clinical trials, underestimating the wealth of basic sciences and animal studies that are precursors to future research. We therefore set out to perform a systematic review of the literature to assess the translation of stem cell therapy to explore what research had been carried out at each of the stages of translation from bench-top (in vitro), animal (pre-clinical) and human studies (clinical) and assemble an evidence-based cascade for the responsible introduction of stem cell therapy for cartilage defects. This review was conducted in accordance to PRISMA guidelines using CINHAL, MEDLINE, EMBASE, Scopus and Web of Knowledge databases from 1st January 1900 to 30th June 2015. In total, there were 2880 studies identified of which 252 studies were included for analysis (100 articles for in vitro studies, 111 studies for animal studies; and 31 studies for human studies). There was a huge variance in cell source in pre-clinical studies both of terms of animal used, location of harvest (fat, marrow, blood or synovium) and allogeneicity. The use of scaffolds, growth factors, number of cell passages and number of cells used was hugely heterogeneous. SHORT CONCLUSIONS: This review offers a comprehensive assessment of the evidence behind the translation of basic science to the clinical practice of cartilage repair. It has revealed a lack of connectivity between the in vitro, pre-clinical and human data and a patchwork quilt of synergistic evidence. Drivers for progress in this space are largely driven by patient demand, surgeon inquisition and a regulatory framework that is learning at the same pace as new developments take place

THE IMPACT OF THE INSTRUMENT IN VELOCITY MEASUREMENTS IN AN OPEN CHANNEL WITH A POROUS BED

In this study, the impact of the type of instrument used [hot-film anemometry and particle image velocimetry (PIV)] in velocity measurements in open channels with a porous bed is investigated. Individual experiments using both the hot-film anemometry and PIV methods were conducted. Initially, the experiments were performed with the hot-film anemometry method and then with the PIV method in open channels with a porous bed under the same conditions. To simulate the porous bed, porous filters, flexible vegetation, gravel beds, and rod bundles with the same porous thickness and the same porosity were used. The velocity distribution of the flow above the porous bed at different total water heights and the same channel slope was evaluated. The results showed that different instruments influence the velocity distribution of the flow, especially in the case of rod bundles. The results in the other cases (porous filters, flexible vegetation, and gravel bed) showed good agreement between the two methods regarding the velocity distribution. © 2017 by Begell House, Inc

PREFACE: THE 2ND EWAS INTERNATIONAL CONFERENCE ON EFFICIENT & SUSTAINABLE WATER SYSTEMS TOWARD WORTH LIVING DEVELOPMENT

[No abstract available

Turbulent structure in uniform inclined open channel flow over different rough porous beds

In this study the effects of the different rough porous beds in an open inclined channel are studied experimentally for impermeable and permeable porous bed. For the simulation of porous bed two different types of permeable bed with the same thickness (s′=3 cm) and the same porosity ε=0.70 are used: (a) porous filters and (b) gravel bed. Laboratory experiments were used for the calculation of turbulent velocity profiles. Measurements of velocity were taken for inclined channel for three different slopes (S=−0.002, S=−0.004 and S=−0.006) and for five different flow depths (h=5 cm, 7 cm, 9 cm, 11 cm and 13 cm). The total discharge Q varies from 0.78 to 1.31 l/s. The measurements were obtained using a two-dimensional (2D) Particle Image Velocimetry (PIV). The total discharge was estimated using a calibrated venture apparatus. Results showed that the presence of rough porous bed in inclined open channels influence significantly the turbulent characteristics of the flow in comparison with impermeable open channels with the same slopes. © 2016 International Research and Training Centre on Erosion and Sedimentation/the World Association for Sedimentation and Erosion Researc

THE INFLUENCE OF DIFFERENT TYPES OF PERMEABLE BED (FLEXIBLE VEGETATION AND INFLEXIBLE ROD BUNDLE) IN GRAVITY CURRENTS

In this study, experiments were performed in a laboratory tank to investigate the effect of a permeable bed (flexible or inflexible) on the movement of gravity currents. The vegetation in the bed of the laboratory tank was simulated initially with grass to create flexible vegetation and then with rod bundles to create inflexible vegetation with the same vegetation bed height (hv = 10 cm). The number of rod bundles was 6200 m2 and the density of the grass (number of shoots per square meter) was 3 shoots/cm2. The density of the vegetation bed, α, in both cases was the same and was calculated as being equal to 0.20 cm-1. The experiments were carried out to investigate the effect of different permeable beds on the movement of gravity currents. The experiments were carried out in a laboratory tank, in which a removable thick vertical partition separated the two fluids (clear water and well-mixed saltwater) at density differences of 2%, 4%, and 6%. After removal of the partition, the created gravity current was monitored by a high-definition digital video camera. The movement of the current was studied (distance covered, effect of differences in density, effect of vegetation height). The experimental results were compared with experimental data from previously published research on gravity currents without the presence of a permeable bed and gravity currents through a random array of rigid, emergent cylinders that represented a canopy of aquatic plants. © 2017 by Begell House, Inc

Velocity profiles in a random porous bed

In this study the velocity distribution of the fluid flow through and over a random porous bed is investigated. The different porous bed and the different porosity influence significantly the form of the velocity profiles. The measurement method should be non-intrusive to avoid any damage to the porous bed and turbulence to the flow. The random and complex structure of the porous bed creates many problems for the researchers because the conditions at the interface are complicated. A series of experiments were conducted with various types of porous beds and the results show that the different type of bed influences with different way the velocity profiles. Also the velocity profiles are found to be dependent on Reynolds number. © 2021 by Begell House, Inc. www.begellhouse.co

The impact of the instrument in velocity measurements in an open channel with a porous bed

In this study, the impact of the type of instrument used [hot-film anemometry and particle image velocimetry (PIV)] in velocity measurements in open channels with a porous bed is investigated. Individual experiments using both the hot-film anemometry and PIV methods were conducted. Initially, the experiments were performed with the hot-film anemometry method and then with the PIV method in open channels with a porous bed under the same conditions. To simulate the porous bed, porous filters, flexible vegetation, gravel beds, and rod bundles with the same porous thickness and the same porosity were used. The velocity distribution of the flow above the porous bed at different total water heights and the same channel slope was evaluated. The results showed that different instruments influence the velocity distribution of the flow, especially in the case of rod bundles. The results in the other cases (porous filters, flexible vegetation, and gravel bed) showed good agreement between the two methods regarding the velocity distribution. © 2017 by Begell House, Inc

Preface: The 2nd EWAS international conference on efficient & sustainable water systems toward worth living development

[No abstract available