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Josef Vedral
EXPONENTIAL FIT TEST - THEORETICAL ANALYSIS AND PRACTICALLY IMPLEMENTATION

ADC testing by means of exponential signal is presented in the article. Time and frequency analysis of the signal is performed and Signal-to-Noise Ratio and Effective Number of Bits is calculated by means of Exponential Fit Test. The approach has been verified on 24-bit Flexible Resolution Digitizer PXI-5922 by National Instruments. Using exponential signal as the digitizer input, the SINAD = 106 dB corresponding to ENOB = 17,3 bits has been achieved. The difference of 1,5 bit was most probably caused by exponential signal frequency spectra decrease. Results comparable with classical sine-fit method indicate the possibility of consideration of the proposed method as an alternative digitizer test method. Achieved results prove the method applicability for dynamic testing of up to 16 bit digitizers, and method simplicity allows for embedded applications. The frequency spectra can be easily modified by changing the time constant of RC element.

David Sarrià, Joaquín Del Río, Antoni Mànuel, Jacopo Aguzzi, José Antonio García, Francesc Sardà
ACTOGRAPHIC DETECTION SYSTEM BASED ON INFRARED AND COMPUTER VISION TECHNOLOGIES TO MEASURE THE BEHAVIOUR OF SPECIES

An automated acquisition system has been developed to measure the behavioral activity rhythms of marine species. The system has been developed using infrared and computer vision technologies by a distributed topology, different experimentations can be done at the same time if the units are repeated and connected to the main computer. The developed system consists primarily in custom low cost acquisition and illumination units with USB interface that allows the acquisition from different photodiodes sensors and to illuminate with a programmable photoperiod. The main computer controls all the connected units and processes the incoming information of behaviour from the sensors to show the activity rhythm of the species under study in association with artificially generated light cycles. The system is complemented with low cost cameras, with different vision algorithms the behaviour of the animals can be extracted.

Arianna Mencattini, Giulia Rabottino, Marcello Salmeri, Federica Caselli,Roberto Lojacono
FEATURES EXTRACTION FOR MICROCALCIFICATION CLUSTERS CLASSIFICATION IN DIGITAL MAMMOGRAMS

Breast cancer is the first leading cause of death by cancer for women. To increase the survival rate it is necessary to detect lesions as soon as possible. Most early breast cancer can be diagnosed by detecting microcalcification clusters in mammographic images. The clusters appear as groups of small, bright particles with arbitrary shapes and distribution. Because of human factors such as subjective or varying decision criteria, distraction by other image features, large number of images to be inspected, or simple oversight, some diagnosis are missed.In this paper, we propose a method to classify clusters of microcalcifications characterizing the lesion by the extraction of geometrical (2D) and textural (3D) features. Then, through a statistical analysis of these features, we can choose the most discriminating between benign and malignant lesions and so design the classifier.

Giulia Rabottino, Arianna Mencattini, Marcello Salmeri, Federica Caselli, Roberto Lojacono
MASS CONTOUR EXTRACTION IN MAMMOGRAPHIC IMAGES FOR BREAST CANCER IDENTIFICATION

Mammography is the most effective tool now available for an early diagnosis of breast cancer. However, the detection of cancer signs in mammograms is a difficult task owing to the great number of non pathological structures which are also present in the image. It has been shown that in current breast cancer screenings 10%–25% of the tumors are missed by the radiologists. For this reason, a lot of research is currently being done to develop systems for Computer Aided Detection (CADe). Probably, some causes of the false–negative screening examinations are that tumoral masses have varying dimension and irregular shape, their borders are often ill–defined and their contrast is very low, thus making difficult the discrimination from parenchymal structures. Therefore, in a CADe system a preliminary segmentation procedure has to be implemented in order to separate the mass from background tissue. In this way, various characteristics of the segmented mass can be evaluated, which may be used in a classification step to discriminate pathological and negative cases. In this paper we describe an effective algorithm for massive lesions segmentation based on region–growing technique and we provide full details of the performance evaluation procedure used in this specific context.

C.Donciu, O.Costea
VISION BASED INTELLIGENT SEMAPHORING SYSTEM

The present paper suggest making an intelligent video system of command over crossroads with traffic lights, its main goal being to diminish of traffic congestions, to improve vehicle speed, to reduce environment pollution and to improve negative effects of traffic congestion over the physic and psychic state of the population. The architecture of the suggested system is made on a hardware level from three different areas: the video sensor’s level, the computer process level and the represented execution level and the traffic-lights that exist in the crossroad. The software architecture of this system is made out of the main routine and a number of secondary routines of image processing and of the Fuzzy command. The existing systems are useful only in low traffic crossroads, being able to interpret informations only from the near proximity of the sensors, but unable to estimate the number of vehicles waiting in line on a traffic lane.

Biserka Mladinic, Tijana Parlic-Risovic
ADDITIONAL CONTROL OF AMBIENT CONDITIONS IN MASS METROLOGY AND ITS INFLUENCE ON MEASUREMENT QUALITY

Mass determination by use of mass comparators is influenced by different parameters including the conditions of ambient air. Having a look at the temperature of weights and the gravitational field gradients, the relatively small impact of these parameters on mass determination can be easily determined on the base of reproducible measurement results. Of metrological interest is the air density determination and control during a measurement series that could be used to improve the quality of measurement. The influence of temperature change as a function of time and its control simultaneously during the weighting process is discussed. The implementation and use of small climate chambers around the mass comparators to smooth out the temperature and relative moisture variations is described and discussed.

Paul Hohmann
CONCEPT OF A TORQUE CALIBRATION UNIT FOR LOW RANGES BASED ON AIR BEARING COMBINATION

The need to calibrate torque in low ranges is given in case of dentist tools, viscometry or friction measurement in ball bearings. Ranges starting about 0,005 N·m as an example, is the target of the following description. A theoretic possibility is shown how to handle all disturbing influences in using mass beam systems as a basic quantity.

Aimo Pusa
TRACEABILITY OF THE CALIBRATION OF TEST CAR FOR ROLL BRAKE TESTER

The calibration of the roll brake tester for trucks has been made general by direct loading of the force transducer. That means to ignore the complete force transmission to rollers, which are in contact to trucks wheel. To be able calibrate exactly the braking force the Finnish institute YTOL has developed a test car to measure direct this braking force. The car has an extra axle with free rotating wheels and braking equipments as well the torque measuring devices. The axle can be moved in vertical position to have the weight maximum 4000 kg on the axle. Raute-MIKES had the task to realise the calibration of this measurement device. The calibration has been made with a 20 kN·m reference torque transducer, which is calibrated static by PTB. The calibration of the brake measurement system has been made as dynamic with the speed of braking as static.

C. Dogan, O. Akkoyunlu, C. Kuzu
DEVELOPMENT OF THE 1 kN·m STATIC TORQUE STANDARD MACHINE AT UME

In the last decade, the increase in the need for the accuracy of the torque metrology created an obligation to produce a new torque standard machine for precise measurement of torque. This paper summarizes the torque standard machine designed and manufactured at UME with the range from 2 N·m up to 1 kN·m. In this machine torque is realized by a lever-mass system. Nominal force arm length of the lever is 0.5 m and constant. In each side of the lever, there are 6 different weight sets; and each set is containing 13 individual mass-stacks. For minimizing the torque loss at fulcrum an aerostatic bearing is used, and the change in the lever position due to the dead weights loading is corrected.

Jong-Ryeol Noh, Jae-Young Jeon
DEVELOPMENT AND EVALUATION OF 6-COMPONENT LOAD CELL FOR LAND-BASED TEST OF HELICOPTER ROTOR DYNAMICS

A 6-component force transducer was developed and evaluated for small-scale model test of helicopter rotor dynamics. The evaluation of the transducer was done mainly through interference check using multi-component calibration procedures. In this paper, the design and analysis process and the related results are verified through calibration results. The force transducer was designed to fix to rotating hub, and dominant force component was lifting force with maximum 1000 lb. From rotating characteristics, fail-safe structure was required to prevent the rotor from bursting out in case of rotor failure. The sensing element was designed with structural symmetry for selfcompensation by full bridge circuit and the expected deformation was analyzed by using finite element method.

Page 775 of 936 Results 7741 - 7750 of 9356