Derivation of supersaturation during precipitation from the mixing pattern of an inert tracer in the same device: case of partially premixed feed streams

International audienceThe average supersaturation field is predicted for precipitations in the case of partially premixed feed streams by a simple mixing model from a couple of successive experiments with the same inert tracer by Planar Laser Induced Fluorescence and using a single camera. Then, the mathematical derivation is different from that one used for the unmixed feed case. The corresponding experiments have been achieved in a 90 impinging jets premixer and the supersaturation field was predicted. Due to the non-simultaneity of tracer experiments, a calculation of the averaged nucleation flux is not possible in the premixed feed case. Nevertheless, a comparison between different premixers can be done on the basis of the generated supersaturation levels and fouling risks

Derivation of supersaturation and nucleation flux in a stirred tank from tracer concentration measurements

15th International Symposium on Industrial Crystallization, SORRENTO, ITALY, SEP 15-18, 2002International audienceThe PLIF (Planar Laser Induced Fluorescence Technique) method is applied to determine experimentally the field of supersaturation in a separate double jet reactive precipitator from the local instantaneous field of concentrations of an inert tracer. The nucleation flux in the mixing region is derived

Derivation of supersaturation and nucleation flux during precipitation from the mixing pattern of an inert tracer in the same device: case of unmixed feed streams

International audienceInert liquid tracer concentrations in a continuous mixer are analyzed by planar laser induced fluorescence (PLIF). Special attention is paid to the two separated entering feed streams containing the tracer solution or pure solvent. From the instantaneous tracer concentration fields, the method proposed allows one to easily calculate the instantaneous supersaturation fields, which would be obtained in the same mixing device with reagents instead of an inert tracer solution and pure solvent. A typical mixing situation in a stirred tank with separated feed streams is investigated. Maps of averaged supersaturation and averaged nucleation flux are yielded with high spatial resolution of a few tens of micrometers for each pixel. The method gives interesting indications about the ability of a given precipitator geometry to generate coarse or fine particles. However, it cannot be extended straightforward to partially premixed feed streams without the use of a mixing model

The mixed analog/digital shaper of the LHCb preshower

The LHCb preshower signals show so many fluctuations at low energy that a classical shaping is not usable at all. Thanks to the fact that the fraction of the collected energy during a whole LHC beam crossing time is 85%, we studied the special solution we presented at Snowmass 1999 workshop. This solution consists of 2 interleaved fast integrators, one being in integrate mode when the other is digitally reset. Two track-and-hold systems and an analog multiplexer are used to give at the output 85% of the signal plus 15% of the previous one. These 15% are digitally computed from the previous sample, and subtracted. A completely new design of this solution had to be made. This new design is described, including new methods to decrease the supply voltage and the noise, as well as to increase the quality of the reset and the linearity. An output stage, consisting of an AB class push-pull using only NPN transistors is also described. Laboratory and beam test results are given. (5 refs)

A very-front-end ADC for the electromagnetic calorimeter of the International Linear Collider

A 10-bits pipeline Analog-to-Digital Converter (ADC) is introduced in this paper and the measurements carried out on prototypes produced in a 0.35 µm CMOS technology are presented. This ADC is a building block of the very-front-end electronics dedicated to the electromagnetic calorimeter of the International Linear Collider (ILC). Based on a 1.5-bit resolution per stage architecture, it reaches the 10-bits precision at a sampling rate of 4 MSamples/s with a consumption of 35 mW. Integral and Differential Non-Linearity obtained are respectively within ±1 LSB and ±0.6 LSB, and the measured noise is 0.47 LSB at 68% C.L. The performance obtained confirms that the pipeline architecture ADC is suitable for the Ecal readout requirement

Seismic Vulnerability Analysis of a Coupled Tank-Piping System by Means of Hybrid Simulation and Acoustic Emission

AbstractIn order to shed light on the seismic response of complex industrial plants, advanced finite element models should take into account both multicomponents and relevant coupling effects. These models are usually computationally expensive and rely on significant computational resources. Moreover, the relationships between seismic action, system response and relevant damage levels are often characterized by a high level of nonlinearity, which requires a solid background of experimental data. Vulnerability and reliability analyses both depend on the adoption of a significant number of seismic waveforms that are generally not available when seismic risk evaluation is strictly site-specific. In addition, detection of most vulnerable components, i.e., pipe bends and welding points, is an important step to prevent leakage events. In order to handle these issues, a methodology based on a stochastic seismic ground motion model, hybrid simulation and acoustic emission is presented in this paper. The seismic model is able to generate synthetic ground motions coherent with site-specific analysis. In greater detail, the system is composed of a steel slender tank, i.e., the numerical substructure, and a piping network connected through a bolted flange joint, i.e., the physical substructure. Moreover, to monitor the seismic performance of the pipeline and harness the use of sensor technology, acoustic emission sensors are placed through the pipeline. Thus, real-time acoustic emission signals of the system under study are acquired using acoustic emission sensors. Moreover, in addition to seismic events, also a severe monotonic loading is exerted on the physical substructure. As a result, deformation levels of each critical component were investigated; and the processing of acoustic emission signals provided a more in-depth view of the damage of the analysed components