Image processing techniques for the characterization of explosively driven dispersions

PresentationDispersions driven by explosions are challenging to characterize mainly due to the extreme test conditions, the different time and spatial scales of the flow, and the variation of intensity due to the combustion. An intensity based optical method to characterize the dispersion driven by an explosion is proposed. The velocity and intensity maps of the dispersion are accessed through the post- processing of the images of the dispersion. These images can be obtained either from a global visualization (using a light source, such as in the image given in Figure 1, or the combustion light itself) or from a transversal visualization (using a laser sheet illuminating inside the cloud, such as in the image given in Figure 2). The developed method is organized into three steps. First, the contour of the cloud is detected via a dynamic grey-scale threshold criterion. The dispersion contours allow the computation of the velocity of the expansion as long as the plume presents a regular edge. Then, Large-Scale Particle Image Velocimetry technique is applied to obtain the velocity map of the dispersion. Additionally, information about the combustion phenomenon can also be accessed via an intensity-based analysis. The method has been initially verified using a numerical test case. It has been thereafter applied on different experimental measurements presenting challenging features such as variations of light intensity, time scales, and spatial scales

Methods for Establishing a Renal Cell Carcinoma Tumor Spheroid Model With Immune Infiltration for Immunotherapeutic Studies

Tumor spheroids play an increasingly important role in cancer research. Their ability to recapitulate crucial features of tumor biology that are lost in the classically used 2D models along with their relative simplicity and handiness have made them the most studied 3D tumor model. Their application as a theranostic tool or as a means to study tumor-host interaction is now well-established in various cancers. However, their use in the field of Renal Cell Carcinoma (RCC) remains very limited. The aim of this work is to present methods to implement a basic RCC spheroid model. These methods cover the steps from RCC tumor dissociation to spheroid infiltration by immune cells. We present a protocol for RCC dissociation using Liberase TM and introduce a culture medium containing Epithelial Growth Factor and Hydrocortisone allowing for faster growth of RCC primary cells. We show that the liquid overlay technique allows for the formation of spheroids from cell lines and from primary cultures. We present a method using morphological criteria to select a homogeneous spheroid population based on a Fiji macro. We then show that spheroids can be infiltrated by PBMCs after activation with OKT3 or IL-15. Finally, we provide an example of application by implementing an immune spheroid killing assay allowing observing increased spheroid destruction after treatment with PD-1 inhibitors. Thus the straightforward methods presented here allow for efficient spheroid formation for a simple RCC 3D model that can be standardized and infused with immune cells to study immunotherapies

Experimental investigation of blast wave propagation in an urban environment

PresentationLab-scale experimental investigations on blast wave propagation in a complex environment are proposed in this paper. Studies of blast propagation are described in the literature, but only a few studies at lab-scale were found while this scale option represents an economic and safe approach. Five experimental configurations, built with wood boxes on a 2.8 m wood table, are tested in a 1:200 reduced scale using three types of explosives. Several characteristics of the explosives are given: the geometry of the explosion, the repeatability, and the TNT equivalent. An overview of impacts of a complex environment on the blast wave characteristics is proposed. The urban configurations investigated are the straight street, the T-junction, the cross junction, and the channeling. Investigations on reduced-scale effects on blast measurement and characteristics are detailed

BLEVE Overpressure: Multiscale Comparison of Blast Wave Modeling

International audienceBLEVE overpressure modeling has been already widely studied but only few validations including the scale effect have been made. After a short overview of the main models available in literature, a comparison is done with different scales of measurements, taken from previous studies or coming from experiments performed in the frame of this research project. A discussion on the best model to use in different cases is finally proposed

Safety Science

International audienceBLEVE Blast wave Overpressure Modeling Moving shock Stationary shock a b s t r a c t The overpressure produced by the boiling liquid expanding vapor explosion (BLEVE) is still not well understood. Various methods have been published on the overpressure modeling in the far field. They mostly differ by the modeling of the expansion energy, used to scale the distance to the source where the overpressure needs to be calculated. But these methods usually include a experimentally fitted reduction factor, and are mostly overestimating the overpressures. Today there is a growing interest in modeling the BLEVE overpressure in the near field, for studying the blast effect on critical infrastructure such as bridges and buildings. This requires a much better understanding of the BLEVE blast. This paper goes deeper in the understanding of the physical phenomenon leading to the BLEVE blast wave generation and propagation. First, mid-scale BLEVE experiments in addition to new experimental data for near field blast from a small scale supercritical BLEVE are analyzed. And second, an analysis method of the shocks observed in the experiments is presented based on fundamental gas dynamics, and allows the elaboration of a new modeling approach for BLEVE overpressure, based on the calculation of the initial overpressure and radius of the blast