Search results for "technical"

Direct measurement of forces between particles and bubbles

1999

One of the elementary stages of the flotation process is the formation of an aggregate between the particle and a bubble. This aggregate formation is governed by hydrodynamic, capillary and interparticle forces. During the last four years, techniques have been developed to measure directly the force between a colloidal particle and a bubble. These techniques are closely related to the development of atomic force microscopy. Advantages and possibilities, as well as limits and drawbacks are described.

Flotation with sedimentation: Steady states and numerical simulation of transient operation

2020

Abstract A spatially one-dimensional model of the hydrodynamics of a flotation column is based on one continuous phase, the fluid, and two disperse phases: the aggregates, that is, bubbles with attached hydrophobic valuable particles, and the solid particles that form the gangue. A common feed inlet for slurry mixture and gas is considered and the bubbles are assumed to be fully aggregated with hydrophobic particles as they enter the column. The conservation law of the three phases yields a model expressed as a system of partial differential equations where the nonlinear constitutive flux functions come from the drift-flux and solids-flux theories. In addition, the total flux functions are …

Soil slope consolidation processes induced by drainage galleries with drainholes

2004

Segregated ice and liquefaction effects on compaction of fragipans

2004

The brittleness of fragipans is generally ascribed to the close-packing fabric arrangement acquired at the initial step of pedogenesis thanks to physical processes. However, there is an on-going debate over the agent causing soil densification. In this work, we tested the plausibility that ice segregation or liquefaction could have been the cause of the compaction of four fragipans. Two of them are located in nonseismic areas that have experienced periglacial conditions; one is from a strongly seismic area not affected by periglacial conditions, while the fourth site underwent moderate seismic activity and slight periglacial conditions. After disaggregation in the laboratory, soil specimens…

Encoding Invariances in Remote Sensing Image Classification With SVM

2013

This letter introduces a simple method for including invariances in support-vector-machine (SVM) remote sensing image classification. We design explicit invariant SVMs to deal with the particular characteristics of remote sensing images. The problem of including data invariances can be viewed as a problem of encoding prior knowledge, which translates into incorporating informative support vectors (SVs) that better describe the classification problem. The proposed method essentially generates new (synthetic) SVs from the obtained by training a standard SVM with the available labeled samples. Then, original and transformed SVs are used for training the virtual SVM introduced in this letter. W…

Using tablets as tools for learner-generated drawings in the context of teaching the kinetic theory of gases

2014

Even though research suggests that the use of drawings could be an important part of learning science, learnergenerated drawings have not received much attention in physics classrooms. This article presents a method for recording students’ drawings and group discussions using tablets. Compared to pen and paper, tablets offer unique benefits, which include the recording of the whole drawing process and of the discussion associated with the drawing. A study, which investigated the use of drawings and the need for guidance among Finnish upper secondary school students, is presented alongside ideas for teachers on how to see drawing in a new light. peerReviewed

Unsupervised change detection with kernels

2012

In this paper an unsupervised approach to change detection relying on kernels is introduced. Kernel based clustering is used to partition a selected subset of pixels representing both changed and unchanged areas. Once the optimal clustering is obtained the estimated representatives (centroids) of each group are used to assign the class membership to all others pixels composing the multitemporal scenes. Different approaches of considering the multitemporal information are considered with accent on the computation of the difference image directly in the feature spaces. For this purpose a difference kernel approach is successfully adopted. Finally an effective way to cope with the estimation o…

Etude de la construction de compétences sociales par une analyse de l’activité en situation de formation : transformation du rapport à soi et aux aut…

2019

In the field of adult education, the question of social skills emerges from current societal issues. The development of service professions, globalization and the virtualization of organizations involve social skills, combining intrapersonal provisions linked to self-relationship (self-confidence, stress management, etc.) and interpersonal provisions linked to relationships with others (teamwork and networking, empathy, etc.) sought by employers. However, social skills are rarely addressed in adult education because they are considered aspart of “on-the-job” learning (Durand, 2008).This study therefore has a dual epistemic and transformative objective: to know how participation in training …

Incomplete self-similarity and flow velocity in gravel bed channels

2000

Velocity measurements, previously carried out using both a miniature current flowmeter and an acoustic Doppler velocimeter, are used to verify the applicability of the incomplete self-similarity theory to deduce the velocity profile in a gravel bed channel. Then, for the velocity profiles having the maximum value below the free surface and for the S-shaped profiles, the power velocity distribution is corrected using a new divergence function. For each value of the depth sediment ratio the nondimensional friction factor parameter is calculated by integration of the measured velocity distributions in the different verticals of the cross section. Finally, a semilogarithmic flow resistance equa…

Health Insurance Reforms and Health Policies in Rural China

2016

Since the early 2000s, the Chinese government has undertaken a series of reforms in the health sector. Among these, the three most important have been concerned with medical insurance, hospital administration, and pharmaceutical policies. The aims of these reforms were to extend health insurance coverage, to increase the activities and the efficiency of the health establishments, and to improve patient care. This article focuses on two components of these reforms: the development of health insurance in rural areas and the policy on essential medicines in conjunction with hospital reforms. Our longstanding co-operation with a research team from Weifang University and with the Weifang Health …