Turbulence, bubbles and drops

In this thesis, several questions related to drop impact and Taylor-Couette turbulence are answered. The deformation of a drop just before impact can cause a bubble to be entrapped. For many applications, such as inkjet printing, it is crucial to control the size of this entrapped bubble. To study the deforming drop and resulting bubble, a high-speed color interferometry method is developed to dynamically measure the air layer profile under impacting drops. Experiments and accompanying simulations and theory show a pronounced maximum in the entrapped bubble size for a certain impact velocity, caused by competing inertial and capillary effects. The liquid-air interface of a drop impacting on micropatterned surfaces is found to globally resemble the dimple that is created on smooth surfaces, except for an increased dimple height and local symmetry-breaking.\ud To study turbulence in a highly controlled way, the Taylor-Couette system is employed, which consists of flow between two co-axial cylinders that can independently rotate. First, the design and construction of a new Taylor-Couette system with precise temperature control and excellent optical access is treated. Next, the first evidence of multiple turbulent flow states in Taylor-Couette flow is reported, at very high Reynolds number of roughly one million. These states are found to consist of stable roll structures which persist for a Taylor number of up to 1013 and beyond. Additionally, it is found that the rotation ratio of the cylinders is the main parameter that controls the transition. Rich flow phenomena, including an unexpected antisymmetrical roll state, are observed in the aforementioned new TC-setup with a larger aspect ratio. In the last chapter, several flow properties in a setup with a smaller radius ratio of 0.5 are investigated. The strength of the secondary flows in the classical turbulent regime was found to scale as theoretically predicted. Finally, it was shown that velocity profiles with a logarithmic signature are created at plume-emitting regions

Templates for the calibration of elemental mercury gas generators

<p>This repository contains two software templates for the calibration of elemental mercury gas generators. <br>One template is for the single point calibration, and one for the multi point calibration.<br>The template for the single point calibration calculates </p><p>* the output ratio between the measurements of the candidate and the measurements of the reference generator<br>* the corrected candidate concentration<br>* the complete uncertainty budget associated to the measurement.</p><p>The template for the multi point calibration calculates the above listed items for each setpoint plus</p><p>* the coefficients of the calibration curve<br>* the uncertainty associated to the coefficients of the calibration curve.</p><p>Details about the equations implemented can be found in <i>Protocol for the SI-traceable calibration of elemental mercury (Hg0) gas generators used in the field</i>.</p&gt

Outline for the revision of ISO Guide 35

The production of reference materials (RMs) is a key activity for the improvement and maintenance of a worldwide coherent measurement system. As detailed in ISO Guide 33, RMs with different characteristics are used in measurements, such as calibration, quality control and method validation, as well as for the assignment of values to other materials. Currently, ISO Guide 35 is in its third edition after it was revised in 2006. The Guide was developed to support best practices in the value assignment to specified properties of Certified Reference Materials (CRMs). This Guide gives general guidance and explains concepts to assist the understanding and development of valid methods to assign values to the properties of a reference material, including the evaluation of their associated measurement uncertainties, and the establishment of their metrological traceability. From the outcome of a systematic review of ISO Guide 35 among the members of ISO/REMCO, the ISO Committee on Reference Materials, it followed that there is a need for revising the current edition of ISO Guide 35. The mandate for the revision is focused on editorial updates to explain the concepts in more detail. It is not envisaged that major technical changes will be introduced. This paper explains the approach and rationale for the revision of ISO Guide 35 and invites comments from the users of the current edition of ISO Guide 35.JRC.D.2-Standards for Innovation and sustainable Developmen

New Definitions on Reference Materials

The definitions for reference materials and certified reference materials as approved by ISO REMCO are provided and further explained.JRC.D.2-Reference material

The role of values in the consumer brand selection process

Although consumers currently give increasing importance to the values brands represent, limited attention appears to be paid to this subject throughout marketing literature. Therefore, our research addresses the role of values in the brand selection process. Based on a literature study, a conceptual model is presented that incorporates values into the self-congruence theory (Sirgy, 1982) that describes the process by which consumers determine a match between their desires and what brands offer them. A first quantitative survey shows evidence for the relevance of value-congruence for some but not all product categories. We offer several explanations why this might be the case