Impact of a Projectile on a Granular Medium Described by a Collision Model

International audienceWe propose a model for the propagation of energy due to the impact of a granular projectile on a dense granular medium. Energy is transferred from grain to grain during binary collision events. The transport of energy may then be viewed as a random walk with a split of energy during successive collisions. There is a qualitative and quantitative agreement between this simple description and experimental results

Étude expérimentale du processus de collision d'une bille sur un empilement granulaire (application au mécanisme de saltation dans le transport éolien)

Les grains de sables transportés par le vent dans le désert se déplacent par bonds successifs sur un lit granulaire; lors de leur impact sur le sol, ils peuvent éjecter d autres grains. Afin d étudier ce processus, nous avons réalisé une expérience modèle de collision d'une bille sur un empilement de billes identiques. Nous avons réalisé une étude systématique en faisant varier nos paramètres de contrôle (vitesse et angle d impact) dans une large gamme. Les résultats obtenus montrent que la bille incidente, lors du rebond, dissipe moins d'énergie pour des impacts rasants, mais qu en contrepartie, le nombre des grains éjectés est dans ce cas moins important. Les caractéristiques moyennes des éjectats (vitesse et angle d éjection) sont, au premier ordre, insensibles aux caractéristiques cinématiques de la bille incidente. Par ailleurs, nous avons mis en évidence que l énergie cinétique totale des éjectats est directement proportionnelle à la fraction d'énergie fournie au lit.Sand grains transported by the desert wind move in successive jumps on a granular bed. During the impact, they can eject other grains. To study this process, we collided a single bead on a packing of identical grains. We reported the experiment for a broad range of incident speeds and impact angles. The results show that, although the incident bead dissipates less energy for grazing impacts, the number of ejected grains is smaller in this case. The mean values of the ejection speed and ejection angle are, to first order, insensitive to the kinematics characteristics of the incident bead. In addition, the total kinetic energy of ejected beads is directly proportional to the fraction of incident energy given.LIMOGES-ENSCI (870852305) / SudocRENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Study of the collision of one rapid sphere on 3D packings: Experimental and numerical results

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Collision process between an incident bead and a three-dimensional granular packing

International audienceWe report on experimental studies of the collision process between an incident bead and a three-dimensional granular packing made of particles identical to the impacting one. The understanding of such a process and the resulting ejection of particles is, in particular, crucial to describe eolian sand transport. We present here an extensive experimental analysis of the collision and ejection process. The analysis is two dimensional in the sense that we determined only the vertical component Vz of the ejection velocity of the splashed particles and the horizontal component Vx lying in the incident plane. We extracted in particular the distribution of the ejection velocities for a wide range of impact angles i and incident velocity Vi. We show that the mean quadratic horizontal velocity of the splashed particles is almost insensitive to changes in the impact angle and velocity, while the mean quadratic vertical velocity slightly increases with increasing impact velocity as Vi 1/2. Moreover, the mean number of splashed particles per collision is found to be dependent on both the impact angle and velocity, and to scale with the impact speed as Vi 3/2. A consequence of these outcomes is that the sum of the kinetic energy of the splashed particles is directly proportional to the kinetic energy of the incident particle. Finally, we provide the bivariate probability distribution function PVx ,Vz of the ejection velocities and show that it can be approximated by the product of a log-normal distribution and a circular normal one

Leveraging Quantity Surveying Data and BIM to Automate Mechanical and Electrical (M & E) Construction Planning

Despite the great potential of LPS and BIM to improve construction project productivity, the full integration of these modern production and information management systems at the data processing level is not yet achieved. After matching the literature to empirical studies in a Constructive Research Approach, it emerged that very few studies have investigated how buildings’ data could be preserved and continuously evolve during the project lifecycle. Accordingly, we underline the potential role of data warehousing in rendering operational data as a strategic asset for decision making. These findings motivate the present research, which aims to capitalize on quantity surveying data in order to automate the generation of M & E installation schedules. This paper first introduces the system functional requirements. Then, it proposes a conceptual scheme for the planning data mart (a data warehouse subset dedicated to planning subject area). Furthermore, we shed light on the M & E fragnet standardization procedure and how data have been processed. Finally, we present the current software developments to demonstrate the feasibility of this concept

Discrete Element Method studies of the collision of one rapid sphere on 2D and 3D packing

International audienceWe performed numerical simulations of one-bead collision on the surface of a static granular medium. The simulations have been done for two- and three-dimensional packings of beads. The effect of the incident bead velocity, the shot angle, the mechanical parameters and the packing structure are analyzed for ordered and disordered 2D packings and only disordered 3D packings. The 2D results are in good agreement with experimental available data. The 3D simulations give good preliminaries results about the shock-wave propagation through the stacking and provides new insights in the ejection process ("splash function")

Three-dimensional analysis of the collision process of a bead on a granular packing

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Maturity Evaluation Methods for BIM-Based AR/VR in Construction Industry: A Literature Review

The architecture, engineering, and construction (AEC) industry has seen significant development, particularly with the increased adoption of Building Information Modeling (BIM). Despite this progress, the interaction between digital and physical environments remains limited due to the visual limitations provided by the built environment. Although integrating BIM with immersive technologies, such as Augmented Reality (AR) and Virtual Reality (VR), is thought to be an effective solution, not all companies are able to successfully implement these integrated technologies. Therefore, it is essential to learn lessons from maturity evaluation. However, a systematic literature review (SLR) of previous works on maturity evaluation of BIM, AR/VR, and BIM-based AR/VR is lacking. The goal of this research is to provide an SLR of these studies to gain a clearer understanding of the field. From an initial cohort of 942 studies, 27 primary studies were retained based on four search engines. The SLR addresses specific research questions related to demographic information, maturity evaluation background, maturity evaluation tools and approaches, their benefits and limitations, and new perspectives. The main findings reveal that the maturity evaluation of BIM-based AR/VR is still in its early stages. The review also suggests a critical analysis of existing maturity evaluation tools, enabling the interpretation of results in an objective manner. Future research should focus on developing a standardized solution that incorporates best practices and rules that meet the needs of practitioners and researchers

Toward BIM and LPS Data Integration for Lean Site Project Management: A State-of-the-Art Review and Recommendations

Over recent years, the independent adoption of lean construction and building information modeling (BIM) has shown improvements in construction industry efficiency. Because these approaches have overlapping concepts, it is thought that their synergistic adoption can bring many more benefits. Today, implementing the lean–BIM theoretical framework is still challenging for many companies. This paper conducts a comprehensive review with the intent to identify prevailing interconnected lean and BIM areas. To this end, 77 papers published in AEC journals and conferences over the last decade were reviewed. The proposed weighting matrix showed the most promising interactions, namely those related to 4D BIM-based visualization of construction schedules produced and updated by last planners. The authors also show evidence of the lack of a sufficiently integrated BIM–Last Planner System® framework and technologies. Thus, we propose a new theoretical framework considering all BIM and LPS interactions. In our model, we suggest automating the generation of phase schedule using joint BIM data and a work breakdown structure database. Thereafter, the lookahead planning and weekly work plan is supported by a field application that must be able to exchange data with the enterprise resource planning system, document management systems, and report progress to the BIM model