146 research outputs found
Building proper invariants for subgrid-scale eddy-viscosity models
No full textSince direct simulations of the incompressible Navier-Stokes equations are limited to relatively low-Reynolds numbers, dynamically less complex mathematical formulations are necessary for coarse-grain simulations. Eddy-viscosity models for Large-Eddy Simulation is probably the most popular example thereof: they rely on differential operators that should be able to capture well different flow configurations (laminar and 2D flows, near-wall behavior, transitional regime...). Most of them are based on the combination of invariants of a symmetric second-order tensor that is derived from the gradient of the resolved velocity field. In the present work, they are presented in a framework where all the models are represented as a combination of elements of a 5D phase space of invariants. In this way, new models can be constructed by imposing appropriate restrictions in this space. The performance of the proposed models is successfully tested for a turbulent channel flow
Duration of anticoagulation for upper extremity deep vein thrombosis associated with cancer and central venous catheter: Outcome of a cohort study
No full textInternational audienceIntroduction: In cancer patients with catheter-associated upper extremity deep vein thrombosis, 3 months of anticoagulation is recommended. The main objective of this study was to compare the incidence of thrombosis recurrence in these patients in case of continuation or discontinuation of anticoagulation, at the end of 3 months and after catheter has been removed. The secondary objectives were the incidence of major bleeding and death.Material and methods: We conducted a retrospective cohort study including patients with a cancer and a catheter-associated upper extremity deep vein thrombosis.Results: About 60 patients included, 44 stopped anticoagulation after the first 3 months and 16 continued it. The median time between catheter insertion and deep vein thrombosis was 26±83 days. Three recurrences occurred during the one-year follow-up: 2 in the group who stopped anticoagulation, with a cumulative incidence at 1 year of 4,8% (95%IC 1.2-18.1) and 1 in the group who continued anticoagulation, with a cumulative incidence at 1 year of 14.3% (95%IC 2.1-66.6). No major bleeding event occurred in anticoagulation discontinued group. The group who stopped anticoagulation was significantly associated with a lower risk of death (HR 0.21-95%IC 0.09-0.48, P<0.001).Conclusion: The risk of recurrence in cancer patients with a catheter-associated upper extremity deep vein thrombosis was low and statistically comparable between the group who stopped anticoagulation and the group who continued it. These results suggest that anticoagulation after the first 3 months deserves to be considered when catheter is removed
Soil and water management strategies for tidal lowlands in Indonesia
No full textAbstract not availableCivil Engineering and Geoscience
Cintaku Jauh di Pulau Karya F.X Soetopo Ditinjau dari Teknik Bernyanyi Seriosa
No full textTulisan ini membicarakan teknik bernyanyi seriosa pada lagu Cintaku Jauh di Pulau karya F. X. Soetopo. Lagu tersebut dari puisi karya Chairil Anwar yang ditulis tahun 1946. Pada tahun 1985, F. X. Soetopo mengaransemen puisi tersebut dalam sebuah lagu seriosa. Lagu ini menceritakan tentang kisah cinta seorang pria kepada seorang gadis dengan menjalin hubungan jarak jauh. Seorang penyanyi tenor bernama Christopher Abimanyu pertama kali membawakan lagu tersebut di Bentara Budaya Jakarta. Gaya atau teknik bernyanyi yang dibawakan oleh Christopher adalah gaya nyanyian yang lebih menekankan pada penggunaan dinamika (messa di voce) sebagai sumber utama ekspresi keindahan dan penjiwaan saat bernyanyi serta teknik artikulasi, intonasi, dan teknik vokal. Penulis melakukan pengembangan teknik bernyanyi pada lagu Cintaku Jauh di Pulau yaitu penggunaan improvisasi ostinato (riff) terdapat di birama 5 dengan nada berulang-ulang pada ketukan ke-2 dan pentatonik pelog terdapat di birama 12-13 yang dimulai ketukan ke-2 dimulai dengan nada 1-2-4-5-6 (do-re-fa-sol-la) dengan interval melangkah naik, dan juga di birama 22-23 dimulai ketukan ke-3 dimulai dari nada 6-5-4-2-1 (la-sol-fa-re-do) dengan interval melangkah turun. Lagu Cintaku Jauh di Pulau merupakan lagu yang tergolong ke dalam bentuk lagu 5 bagian A-B-B’-C-D-A’ dengan urutan kalimat A (a,b), B (x,y), B’ (x’,y’), C (c,d), D (xx,yy), A’ (a, b’). Penelitian ini menggunakan pendekatan kualitatif deskriptif. Data yang diperoleh berupa observasi melalui YouTube (https://youtu.be/QRVL9vcaQBo), studi pustaka, dan dokumentasi. Hasil dari penelitian ini adalah: 1) Mempertunjukkan lagu tersebut dalam bentuk penampilan secara langsung di Taman Yenny Hendra Bundaran Nommensen, 2) Menggunakan teknik improvisasi ostinato dan pentatonik pelog, 3) Analisis bentuk lagu Cintaku Jauh di Pulau.Kata Kunci: Cintaku Jauh di Pulau; F.X Soetopo; Analisis;EkspresiAbstractThis paper discusses seriosa singing techniques in the song Cintaku Jauh di Pulau Pulau by F. X. Soetopo. The song is taken from Chairil Anwar's poem which was written in 1946. In 1985, F. X. Soetopo arranged the poem to become a seriosa song. This song tells about the love story of a man and a girl who are in a long-distance relationship. The tenor named Christopher Abimanyu performed the song for the first time at Bentara Budaya Jakarta. Christopher's singing style or technique is a singing style that places more emphasis on the use of dynamics (messa di voce) as the main source of expression of beauty and soul when singing as well as articulation techniques, intonation and vocal techniques. The author develops a technique for singing the song Cintaku Jauh di Pulau, namely the use of ostinato (riff) improvisation and pelog pentatonic according to the ability of a presenter. This study uses a descriptive qualitative approach. The data obtained are in the form of observations via YouTube (https://youtu.be/QRVL9vcaQBo), literature studies, and documentation. The results of this study were: 1) Performing songs in the form of live performances at the Yenny Hendra Park Nommensen Roundabout, 2) Using ostinato and pelog pentatonic improvisational techniques, 3) Analysis of the form of the song Cintaku Jauh di Pulau.Keywords: Cintaku Jauh di Pulau; F.X Soetopo; Analysis; Expression
Fluid Flow Visualization through Porous Media
No full textWe have built a set-up enabling direct visualization of fluid displacement and interaction in a transparent porous media at pore scale resolution. We have been able to image successive 2D planes in order to reconstruct the 3D configuration of residual oil after secondary imbibition for mobilization and displacement experiments. We visualized the dynamics of primary drainage and secondary imbibition and studied the non wetting phase ganglia morphologies. For small Ca, the ganglia configuration does not change significantly. However as Ca is increased above a certain threshold we observed that large ganglia break up into smaller ganglia, with the associate decrease in residual oil. By comparing the blob configuration between a mobilization experiment and a displacement experiment the work has clearly delineated the importance of knowing history, and has demonstrated that displacement is likely to be more efficient in recovering oil.Petroleum EngineeringGeoscience & EngineeringCivil Engineering and Geoscience
Assessment of the effect of the reclamation of acid sulphate soil for agricultural development in Vietnam
No full textVietnam is an agricultural country where rice is the main crop cultivated in the Red river delta in the North and in the Mekong delta in the South. Both deltas refer to lowland. However, the degree of development is clearly different between the two deltas. In the Red river delta, the dike system as well as the canal networks have been constructed. Flood is almost controlled. Canal networks have been excavated to supply water to the fields or to evacuate drainage water out of the areas of interest. Meanwhile, there are no dikes in the Mekong delta. This results in flooding every year with a duration of about two months and causing damages to the local people. Canal networks are poor, 5 m/ha on average. Field canals are rarely found in practice. The other constraint for agricultural development is the problem of acid sulphate soil (ASS). This type of soil accounts for a big portion of the total area of the Mekong delta, 1.6 million ha out of 3.9 million ha. Under the pressure of the increasing population growth and the requirement on rice production attention is given to the development of the Mekong delta. Actual and future problems deals with a flood control and soil and water management on ASS. To contribute to the solution of these problems the Plain of Reeds is studied in this thesis. The study focuses on: - development of criteria for dike design and technical specifications for drainage which can be applied in planning, design and construction; - analysis and assessment of possibilities of removal of toxic elements from the potential acid sulphate soil. To reach the objectives mentioned above an analysis of available data has been carried out and three simulation models have been used: the simulation model for acid sulphate soil (SMASS) to predict the duration of land reclamation and to determine strategies of soil and water management; the simulation model for one dimensional unsteady flow in channel systems (DUFLOW) for flood analysis, canal design and water management; and the geographical information system (GIS) for planning activities. The analysis and simulation results show that submerged dikes designed for a return period (T = 3 years) and open drainage systems are appropriate under conditions of the Mekong delta. To enhance the land reclamation and water management a ground water table at 0.2 m-surface is considered as appropriate. Canal networks should be improved to increase the discharge capacity. Water control structures should be constructed to prevent a backwater flow and salt water intrusion under tidal conditions. In addition the GIS shows that the layout of existing canal networks is reasonable. It is possible to lay-out irrigation and drainage canals separately. The reclamation of acid sulphate soils for agricultural development is possible by proper water management measures. Combination of data analysis with the simulation models can deliver more or less the the required information to enable policy makers and decision makers to take proper decisions. However, a study on dynamics of acid sulphate soil and consequences due to reclamation of acid sulphate soils are necessary and recommended to be carried out
Chemical behavior of tungstate solutions. Part 1. A spectroscopic survey of the species involved
No full textThis study is focused on the composition and the evolution of tungstate ions solutions as a function of pH and increasing concentrations. The Raman analysis showed that, during the titration of the tungstate solutions, WO4 2−, HWO4 − ions and probably W2O7 2−, HW2O7 2− and H2W2O7 solvated species could exist in aqueous solutions. For diluted solutions, additions of a strong acid does not cause any precipitation, whereas the formation of the unstable solid tungstic acid (H2WO4 or WO3·H2O) could occur in concentrated solutions
Optimising the ply dropping order in variabel stiffness, variable thickness laminates using stacking sequence tables
No full textModern composite structures oer two avenues of optimising performance. One, optimising a single stacking sequence over the structure leading to constant stiness designs. Two, varying the stiness over the structure. This may be achieved by dropping plies, changing the thickness, or by steering the fibres, changing the fibre angles. Optimising ply drops involves two decisions: the selection of ply drop boundaries, and of the ply drop order. Previous work considered the problems of optimising the fibre angle distribution and ply drop boundaries but ply drop order was pre-specified. This paper extends the work to simultaneously optimise the fibre angle distribution, the ply drop boundaries, and order. The optimisation of fibre angle distribution lends itself to gradient-based methods. The ply drop boundary optimisation is formulated using topology optimisation techniques and is thus also solvable using gradient-based methods. The ply drop order optimisation requires discrete variables and is hence approached using an evolutionary algorithm based on stacking sequence tables. In this paper an e cient multi-step algorithm is developed combining the optimisation of all aspects of variable stiness laminates. The results indicate that significant improvements may be obtained by including the ply drop order in the optimisation at a relatively modest computational cost
Effects of Luminous Furniture on Mood
No full textAbstractPsychological lighting research mostly deals with light effects of lighting, which are above eye-level. This research explores the effects light of a luminous furniture on customer's mood. A laboratory experiment and quasi- experimental method were conducted. The first experiment was intended to identify two variables of a luminous furniture. The quasi-experiment evaluates various effects of lights of two sets of a café luminous furniture. In this experiment, seventy students were involved to report their feelings toward three different luminous furniture settings. The data was analyzed using ANOVA statistic. The result shows that the constant setting of a luminous furniture was the most favorable in influencing people's mood
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