Non-destructive Sensor Research Articles

Ripeness sensor development based on nuclear magnetic resonance

Ripeness is a very important quality factor for the consumer, But non-destructive sensors that enable control of every single fruit instead of a sample set are badly needed. Near infrared has given good results for the determination of sugar in peaches or apples but it is inefficient for thick-skin fruits or small fruits. For these, nuclear magnetic resonance (NMR) can offer many advantages. Low resoltuion NMR spectroscopy has been applied to determine the sugar content in pears, cherries and grapes. The relaxation time t 2 as well as other parameters extracted from the CPMG curve (called the ‘CPMG parameter’) correlated well with the sugar content. The coefficients of correlation are 0.73, 0.85 and 0.93 respectively between the t 2 and the CPMG parameter. The best results are achieved with grapes because this is the commodity which is the closest to regular sugar/water mixtures. Other studies have to be done to integrate the role of firmness and acidity.

Sensor Technology for ZIF Connectors

A zero insertion force (ZIF) connector was designed with the requirement of maintaining a specified contact normal force and wipe sufficient to achieve reliable electrical performance. In order to evaluate the design during its development and to monitor its quality during full scale production, a nondestructive sensor was developed to measure the force and wipe simultaneously. The sensor was built into a steel coupon, and assembled in a benchtop fixture that facilitates ease of alignment and measurement of the contact springs. The coupon can also be mounted on a printed circuit card to enable “in-situ” measurement of connectors assembled in the electronic “cage-like” package. Prior to sensor availability, the connector vendors as well as IBM had other methods of measuring contact force and wipe. These measures had varying accuracies, and were difficult to correlate. The sensor described in this paper was duplicated in order for the vendors and IBM to have a consistent measurement tool.

A system for precise determination of effective atomic number by beta backscatter

A compact instrument capable of determining the effective atomic number (Z/sub eff/) of a target has been developed and characterized. It is a nondestructive sensor which utilizes a cadmium telluride solid-state detector and a /sup 90/Sr//sup 90/Y source in a backscatter geometry. The spectrum of the backscattered beta particles depends on the target atomic number. Measurements show that, by using the mean energy of the backscatter spectrum, the average effective Atomic number can be determined to better than +or-1Z. The system includes data acquisition and analysis software which runs on a personal computer. The system was designed to be flexible enough to be used for a variety of applications by changing the data analysis algorithms and the source type and energy. >

Comparaison de l'évolution de l'indice de réfraction et de la viscosité au cours de la gélification lactique du lait

Summary Comparison of refractive index and viscosity evolution during lactic gelification of milk. A coaxial cylinders viscosimeter coupled with a refractometer were used to follow acid gelification of milk with Streptococcus thermophilus (CNRZ 7 and CNRZ 385). The viscosity and the refractive signal (IR) were functions of pH and increased simultaneously at pH 5.4. At pH 5.0, the viscosity decreased rapidly, while the IR still rised. Significant linear regressions between viscosity (restricted to the rising part of the viscosity time curves) and IR were obtained. These results show that the used refractometer could be a satisfactory non-destructive sensor for milk gelification with lactic acid bacteria. Sorne hypothesis are discussed concerning the phenomena followed by the refractometer.

Measurement of ion beam parameters with electrostatic induction electrodes

One source of information concerning ion beam parameters is the electromagnetic field which can be sensed in a non-destructive manner by means of electrostatic induction electrodes. It is shown that the response of an electrode system is a solution of the Laplace equation with boundary conditions specified by the weighting function of the system. Electrode systems as integral devices can provide information on the beam intensity, transverse beam coordinates, and some coefficients associated with the beam profile. A new class of electrode systems based on the Walsh weighting functions is introduced. Methods are studied for computing the response of electrode systems of a circular as well as of a rectangular cross section. A lower bound, known as the Cramer-Rao bound, on the performance of a measuring system using an electrode system is presented. A concept of spatial filtering is discussed and a novel closed-loop scan generator is proposed. Finally, a brief discussion on the applications of electrode systems indicates that the systems meet requirements for non-destructive sensors suitable for automated equipment employing continuous ion beams.