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It is common for engineers to use countermeasures to protect hydraulic structures against scour. This study aims to explore the effect of jet injection through the pier body as a pier-scour countermeasure. Laboratory experiments were conducted in two different flow depths (10.5 and 28 cm) using 1-jet and 3-jet injections, different jet locations, and angles between the jets under clear-water conditions. The experimental data showed that the most optimal case in terms of pier-scour depth reduction occurred for lower flow depth, higher jet flow rate, and angle between the jets equal to 90°. Moreover, the jets are able to reduce the scour depth, scour volume and upstream slope of the scour hole up to 37.5%, 57%, and 25% for flow depth of 10.5 cm and 31.2%, 37%, and 57% for flow depth of 28 cm, respectively. By increasing the number of jets, turbulent kinetic energy increases, leading to the pier-scour depth decreasing. Key words: bridge pier, local scour, jet injection, scour countermeasure. Les ingenieurs utilisent souvent des mesures de prevention pour proteger les structures hydrauliques contre l'affouillement. La presente etude explore l'effet de l'injection de jets a travers la structure du pilier en tant que mesure contre l'affouillement aux piliers. Des experiences en laboratoire ont ete realisees a deux profondeurs d'ecoulement differentes (10,5 et 28 cm) en utilisant des injections a un et trois jets, divers emplacements de jets et differents angles entre les jets sous des conditions d'eau claire. Les donnees experimentales montrent que le cas le plus optimal en termes de reduction de la profondeur d'affouillement au pilier survenait a la plus faible profondeur d'ecoulement, au debit de jet le plus elevee et a un angle de 90° entre les jets. De plus, les jets peuvent aider a reduire la profondeur d'affouillement, le volume d'affouillement et la pente amont du trou d'affouillement jusqu'a 37,5 %, 57 % et 25 % respectivement pour une profondeur d'ecoulement de 10,5 cm, et 31,2 %, 37 % et 57 % pour une profondeur d'ecoulement de 28 cm. En augmentant le nombre de jets, l'energie cinetique turbulente augmente, engendrant une diminution de la profondeur d'affouillement aux pieux. [Traduit par la Redaction] Mots-cles: pilier de pont, affouillement local, injection de jet, mesure contre l'affouillement., 1. Introduction Local scour is the process whereby sediment is removed from the base or toe of a structure by waves and currents. This is different from general bed erosion [...]

This paper presents the use of x-ray tomography imaging to reconstruct a three-dimensional (3D) digital representation of individual particles in a granular system. The granular system is represented by the mass center coordinates and the morphology representation of each particle. An automated procedure using pattern recognition to identify related particle cross sections in adjacent serial images was developed. Procedures to calculate quantities needed for subsequent simulation of particle behavior including the volume and the momentum of inertia of each particle are also presented. The developments described in the paper enable modeling and simulation of the behavior, and experimental observations of the particle kinematics of real microstructures of granular materials in a true 3D platform. CE Database subject headings: Microstructure; Granular materials; Morphology; X-ray analysis; Radiography; Particles; Digital techniques.

A structural vibration control concept, using piezoelectric materials shunted with real-time adaptable electrical networks, has been investigated. The variable resistance and inductance in an external RL circuit are used as control inputs. An energy-based parametric control scheme is created to reduce the total system energy (the main structure mechanical energy plus the electrical and mechanical energies of the piezoelectric material and electrical circuit) while minimizing the energy flowing into the main structure. Stability of the closed-loop system is proved. The performance of the controller is examined through analyzing a beam example. It is shown that the structure energy level and vibration amplitude can be suppressed effectively.

The paper presents a two-dimensional unsteady-flow model, RBFVM-2D, based on the finite-volume method with a combination of unstructured triangular and quadrilateral grids in a river-basin system. The attractive feature of this model is that it calculate of the mass and momentum flux across each side of elements as a Riemann problem, which is solved using the Osher scheme. This feature enables this model to deal with the wetting and drying processes for floodplain and wetland studies, dam breaking phenomena involving discontinuous flows, subcritical and supercritical flows, and other cases. The computations of tributary inflows and regulated flows through gates, weirs, and culverts or bridges are also included. Sample applications of this model to two dam-break problems showed fairly satisfactory results. Also, this model was applied to a portion of the Kissimmee River Basin in Florida for flow simulations and the results agreed well with the field and laboratory data in a physical-model study of this river reach conducted at the University of California, Berkeley.

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Investigates structural vibration control concept using piezoelectric materials with real-time adaptable electrical network. Adaptive beam structure model for the controller design process; Variables used as control inputs; Creation of energy-based parametric controller for suppression of vibration; Illustration of the effectiveness of the controller.