IMEKO Event Proceedings

Page 5 of 770 Results 41 - 50 of 7695

F. Bitte, H. Mischo, T. Pfeifer, G. Frankowski
3D SURFACE INSPECTION WITH A DMD BASED SENSOR

In this paper a method for non-contact scanning of small structures is presented similar to that of confocal microscopy but using the technology of Digital Micromirror Devices (DMD) instead of ordinary pinholes. It offers parallel scanning of various specimen following to a principle, where a DMD is used for illumination and a selective CCD for detection. The fundamental concepts concerning system layout and system performance as well as measurement results with a first experimental demonstrator are presented.

Ji Qi, Yingzhong Tian, Wenjun Zhang, Albert Weckenmann, Minglun Fang
3D SURFACE MICRO TOPOGRAPHY RECOVERY FROM MULTI-FOCUS IMAGES USING MODIFIED LAPLACIAN OPERATOR

Optical microscopy enables the observation of highly magnified objects and material structures on micro surfaces, however with the weakness that it can only acquire 2D images. In order to observe the areal features more accurately and intuitively, 3D surface micro topography recovery is applied to form a 3D surface model of an object from its 2D image sequence. Optical microscope has a limited depth of focus in large magnification, which makes the area within the depth of focus cleared and other area blurred. So this paper firstly acquires image sequence which obtains all useful information in one view by vertical scanning of the microscope. Secondly, each image is calculated by an appropriate focus measure operator to find the maximum focus measure value and form a 2D fused image. Then the maximum value of each pixel is accurately transferred into a distance value, forming a discrete depth map. After conducting interpolation, fitting and color mapping, a smooth and authentic 3D color model of the measured surface is obtained. Various focus measure operators such as grey level variance are used to compare their performances in 3D model recovery. The superiority of the modified Laplacian operator proposed in this paper is proved by experimenting on measured objects with different micro topography features such as ditch shaped and slope shaped structure. In addition, surface roughness information of Ra and Rz is extracted from the formed 3D models.

Antonis Antonopoulos, Sofia Antonopoulou
3D survey and BIM-ready modelling of a Greek Orthodox Church in Athens

This paper explores the application of two widely-used digital technologies, Structure-from-Motion (SfM) photogrammetry and Building Information Modelling (BIM), in the case of Byzantine ecclesiastical architecture. SfM photogrammetry was used for the 3D documentation of Agioi Anargyroi Greek Orthodox church in Athens, including exterior and internal spaces, using a combination of ground-based and aerial (UAVmounted) photography under rigorous survey control. The resulting point cloud dataset constitutes the primary survey record of the building in its current state (as-existing). Finally, a BIM-ready model of the existing structure was proposed as an alternative method for the production of coordinated 2D drawings and facilitating requirements of subsequent development of the project.

J. Escande, P. Gajan, A. Strzelecki
3D VELOCITY PROFILE RECONSTRUCTION OF GAS FLOW IN A PIPE WITH ULTRASONIC TOMOGRAPHY

Beyond possibilities of simple flowmeters, ultrasonic tomography allows to reconstitute the three-dimensional velocity field over a circular pipe cross section. The differences of transit times between transducers distributed around the pipe are used in an iterative algebraic reconstruction algorithm in order to reconstruct the three velocity components. This experimental method has been tested successfully to quantify the 3D velocity field of various flows (fully developed, asymmetric and swirling air flows).

Richard Steven, Charlie Britton, Joshua Kinney
4”, 0.63 Beta Ratio Cone DP Meter Wet Gas Performance

Cone DP meters are often used for unprocessed natural gas flow metering applications. Unprocessed natural gas flows can have entrained water and light hydrocarbon liquids. Hence, it is important to fully understand the wet gas flow response of cone DP meters. One method of metering the gas flow rate of a wet natural gas flow is to estimate the liquid flow rate (usually a mixture of hydrocarbon liquid and water) from an independent source (such as a tracer dilution technique or test separator histories) and then use a wet gas correction factor or "correlation" to correct for the liquid induced gas flow rate error. It is therefore necessary to have a reliable cone DP meter wet gas correlation for wet natural gas flows where the liquid component is a water and / or a light hydrocarbon liquid mixture.

Shang Wei Lu, Li Tao, Cheng Yong Pei, Wang Yan, Qian Zhao Jun
50 kNm TORQUE STANDARD MACHINE

The paper introduces the working principle of dead-weight balance type 50kNm torque standard machine , which was developed recently. The paper describes in detail the key technique , etc. such as the knife edge supporting technique with high load , the force magnifing technique , the alignment technique and the computer control automatic loading technique , etc. The paper analyses the uncertainty of the machine and the compared and verifyed data with LNE . The uncertainty of the 50kNm torque standard machine arrives at 0.023%(tp=3.1).

Thomas E. Lipe
50-OHM MULTIJUNCTION THERMAL CONVERTERS FOR AC VOLTAGE MEASUREMENTS UP TO 100 MHz

Multijunction thermal converters (MJTCs) are in use as standards for ac voltage measurements at frequencies up to 100 MHz. At the National Institute of Standards and Technology (NIST), MJTCs based on glassy substrates with 50 Ω input impedances are being developed to align more closely with common practice at high frequencies. Preliminary results indicate that 50 Ω MJTCs with excellent properties can be successfully fabricated.

Maria Gabriella Masi, Lorenzo Peretto, Roberto Tinarelli, Luigi Rovati
A  PUPIL SIZE MEASUREMENT SYSTEM FOR THE ANALYSIS OF THE IMPACT OF FLICKER ON HUMAN BEING

The validation of any new model of the human response to flicker requires proper experimental data. Recently, studies have been carried out with the intent of achieving information relevant to the state of annoyance of a human being subjected to light flicker by analyzing the modification of the pupil size. Indeed, it is well known that pupil diameter changes according to the luminous flux variation. According to such a theory the authors developed a measurement system capable of tracing the pupil size variations in time under flicker conditions. This will result of help for further developing the above theory and confirming its correctness and robustness. The presented measurement system will allow measuring the pupil diameter when subjected to flicker with given amplitude, frequency and colour. The technique and the relative system will be examined through the description of some tests executed to evaluate its performance. The good behaviour of the measurement system suggests its future employment for the analysis of flicker effects on human beings.

Jerzy Nabielec
A “BLIND” CORRECTION OF DYNAMIC ERROR OF A NONSTATIONARY FIRST ORDER TRANSDUCER FOR THE PERIODIC CASE – SIMULATION INVESTIGATION

The paper presents an extension of the “blind correction” method with respect to nonstationary transducers of the first order. An analytical description of the measuring channels’ dynamics is presented for the case where both: the measured signal and the measuring channels’ parameters are varying with same fundamental frequency. The influence of the measuring system parameters on the correction accuracy was investigated using the simulation methods.

Mustafa Keskin, Un-Ku Moon, Gabor C. Temes
A 0.9-V 10.7-MHz 3.6-mW Bandpass ∆Σ Modulator Using Unity-Gain-Reset Opamps

A low-voltage and low-power bandpass ∆Σ modulator is described. In this design, two novel ideas are incorporated: unity-gain-reset and integrating-two-path techniques. A test chip, realized in a 0.35- µ m CMOS process and clocked at both 20 and 40 MHz, provided a dynamic range DR = 45 dB and a signal-to-noise+distortion-ratio SNDR = 36 dB for a 100-kHz signal bandwidth at 5MHz center frequency, and DR = 30 dB and SNDR = 32 dB for a 200-kHz BW at 10MHz center frequency. The supply voltage was 0.8 V for 20 MHz clock, and 0.9 V for 40 MHz clock.

Page 5 of 770 Results 41 - 50 of 7695