| 11. |
- Alam, Mohammad Anzar, et al.
(författare)
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Investigation of the surface topographical differences between the Cross Direction and the Machine Direction for newspaper and paperboard
- 2011
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Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 26:4, s. 468-475
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Tidskriftsartikel (refereegranskat)abstract
- Paper and paperboard surface quality is constantly being improved by the industry. This improvement work deals with the essential fact that the surface topography must be measured, both in relation to offline and online measurements for the manufactured products. Most measurements relating to surface topography (especially online) are performed either in the machine direction (MD) or in the cross direction (CD). It has been the opinion of SCA Ortviken AB and Iggesund Paperboard AB that the surface topography amplitudes are almost always higher in the CD than in the MD, for their products which consist of newspaper and paperboard. This article aims to investigate the rela-tionship between the CD and the MD surface topography amplitudes for a wide range of spatial wavelength for both newspaper and paperboard. The tests and investiga-tions have been conducted using an FRT Microprof profilometer within the range 20 μm up to 8 mm, and the results confirm that the surface topography amplitudes are higher in the CD for most of the shorter spatial wavelength within this range. The results also show significant differences between measurements for different paper qualities, suggesting a requirement to investigate the relationship between the CD and the MD topography for all paper and paperboard qualities of interest for a paper or paperboard mill, before a decision is made in relation to a measurement method.
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| 12. |
- Alam, Mohammad Anzar, et al.
(författare)
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Limitation of a line-of-light online paper surface measurement system
- 2014
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Ingår i: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 14:8, s. 2715-2724
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Tidskriftsartikel (refereegranskat)abstract
- A new prototype device has been developed based on a laser triangulation principle to measure online surface topography in the paper and paperboard industries. It characterizes the surface in a wide spatial scale of topography from 0.09-10 mm. The prototype's technique projects a narrow line-of-light perpendicularly onto the moving paper-Web surface and scattered reflected light is collected at a low angle, low specular, and reduced coherent length onto the CCD sensors synchronized with the laser sources. The scattering phenomenon determines surface deviations in the z-direction. The full-width, at half-maximum of a laser line in cross section is sensitive in computation of the surface topography. The signal processing aspect of the image processing, for example, threshold and filtering algorithms are also sensitive in estimating the accurate surface features. Moreover, improper light illumination, intensity, reflection, occlusion, surface motion, and noise in the imaging sensor, and so forth, all contribute to deteriorate the measurements. Optical techniques measure the surface indirectly and, in general, an evaluation of the performance and the limitations of the technique are both essential and challenging. The paper describes the accuracy, uncertainty, and limitations of the developed technique in the raw profiles and in terms of the rms roughness. The achieved image subpixel resolution is 0.01 times a pixel. Statistically estimated uncertainty (2σ) in the laboratory environment was found 0.05 μm for a smooth sample, which provides a 95% confidence level in the rms roughness results. The depth of field of the prototype is ~2.4 mm.
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| 13. |
- Alam, Mohammad Anzar
(författare)
-
Online optical method for real-time surface measurement using line-of-light triangulation
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Real time paper surface-web measurement is one of the challenging research fields. The traditional laboratory method has many limitations and is unable to measure the entire tambour during the manufacturing process. It has been necessary to develop an online technique that could measure the surface topography in real time. An optical technique was developed, based on laser triangulation, and is applied to develop a new prototype device, which characterizes high speed paper-web surfaces over a wide scale of spatial wavelengths spectrum and computes the surface roughness in real time. The used multi channel pulsed laser diode, source of illumination onto the paper-web, is of benefit due to its low coherence length and is capable to deliver a powerful burst of light beam over a 1 µs duration, which delivers energy of 100 µJ per pulse. The short exposure time avoids blurriness in the acquired images which could possible due to the high speed and vibrations on the paper-web.The laser beam is shaped into a narrow line-of-light using cylindrical lenses and is projected onto a paper-web surface, which covers a physical length of about 210 mm. The created line-of-light cross section full width at half maximum, FWHM Gaussian distribution, is 2-3 pixels on the image. The line-of-light is projected onto the paper-web perpendicular to the plane of the surface. The low angled, low specular, reduced coherence length, scattered reflected laser line is captured by the 3 CCD sensors, which are synchronized with the laser source. The low specular light ensures to avoid saturation of the imaging sensors if the surface is very smooth, and obliquely captures the z-directional fine feature of the surface.The scattered phenomenon of the reflected light is responsible for the surface irregularity measurements. The basic image processing algorithm is applied in order to remove noise and cropped the images widthwise so that only pixels above a preset threshold gray level can be processed, which enables efficient real time measurement. The image is transformed into a 1D array using the center of gravity, COG. The accuracy and precision of the COG depends on the line-of-light FWHM, which, in turn, is responsible for the accuracy, noise and the resolution of the developed technique. The image subpixel resolution achieved is 0.01 times a pixel and uuncertainty in the raw data is 0.43 µm while it is 0.05 µm in the rms roughness.The signal processing steps combining the B-Spline filter and the filter in the spatial frequency domain were employed in order to separate roughness, waviness, and form and position error in the raw profile. The prototype is designed to measure online surface roughness and to characterize surface in a spatial wavelength spectrum from 0.09 to 30 mm, which is extendable to any required spatial range in order to cover a wide scale surface feature such as micro roughness, macro roughness and waviness. It is proven that exploitation of a simple laser triangulation technique could lead to an improvement in the overall quality and efficiency in the paper and paperboard industries and it can also be of potential interest for the other surface characterization problems.
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| 14. |
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| 15. |
- Alam, Mohammad Anzar, et al.
(författare)
-
Real time surface measurement technique in a wide range of wavelengths spectrum
- 2014
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Ingår i: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 14:1, s. 285-294
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Tidskriftsartikel (refereegranskat)abstract
- Real time surface topography measurement in the paper and paperboard industries is a challenging research field. The existing online techniques measure only a small area of paper surface and estimate topographical irregularities in a narrow scale as a single predictor. Considering the limitations and complications in measuring the surface at high speed, a laser line triangulation technique is explored to measure surface topography in a wide scale. The developed technique is new for the paper and paperboard application that scans a line onto the paper-web surface up to 210 mm in length in the cross machine direction. The combination of a narrow laser linewidth imaging, a subpixel resolution, and the selection of a unique measurement location has made it possible to measure roughness and simultaneously characterize paper surface topography from 0.1 to 30 mm spatial wavelength. This spatial range covers wide scale surface properties such as roughness, cockling, and waviness. The technique clearly distinguishes and characterizes the surface of newspaper, and lightweight coated, coated, and uncoated paperboard in real time during the paper manufacturing process. The system temporal noise for the average roughness is estimated as 37 dB. The signal to noise ratio found is from 5.4 to 8.1 in the short spatial wavelength up to 1 mm, whereas it is more than 75 in the long spatial wavelength from 5 to 10 mm.
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| 16. |
- Bader, Sebastian, et al.
(författare)
-
Remote image capturing with low-cost and low-power wireless camera nodes
- 2014
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Ingår i: Proceedings of IEEE Sensors. - : IEEE Sensors Council. ; , s. 730-733
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Konferensbidrag (refereegranskat)abstract
- Wireless visual sensor networks provide featurerich information about their surrounding and can thus be used as a universal measurement tool for a great number of applications. Existing solutions, however, have mainly been focused on high sample rate applications, such as video surveillance, object detection and tracking. In this paper, we present a wireless camera node architecture that targets low sample rate applications (e.g., manual inspections and meter reading). The major design considerations are a long system lifetime, a small size and a low production cost.We present the overall architecture with its individual design choices, and evaluate the architecture with respect to its application constraints. With a typical image acquisition cost of 1.5 J for medium quality images and a quiescent power demand of only 7 uW, the evaluation results demonstrate that long operation periods of the order of years can be achieved in low sample rate scenarios.
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| 17. |
- Cheng, Peng
(författare)
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Applications of embedded sensors in loader crane positioning and rotor RPM measurement
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, two novel applications involving embedded sensors arestudied, one dealing with loader crane positioning and the other involving rotorRevolutions Per Minute (RPM) measurement. The thesis presents a generalintroduction to the embedded sensor, its architecture and its use in mechanicalindustry, and provides the reader with an overview of conventional sensortechnologies within the fields of angle sensors and angular speed sensors, coveringtheir working principles, features, advantages and disadvantages and typicalapplications. The particular problems associated with the use of conventionalsensors in both loader crane positioning and rotor RPM measurement aredescribed and these problems provided the motivation for the designs of theembedded sensor systems developed in this thesis.In the case of the loader crane positioning, the origins of the project and thespecial requirements of the application are described in detail. In addition, apreliminary study is conducted in relation to the idea of a contactless joint angularsensor using MEMS inertial sensors in which four different methods, namely, theCommon-Mode-Rejection with Gyro Integration (CMRGI), Common-Mode-Rejection (CMR), Common-Mode-Rejection with Gyro Differentiation (CMRGD)and Distributed Common-Mode-Rejection (DCMR), are conceived, modeled andtested on a custom-designed prototype experimental setup. The results gatheredfrom these four methods are compared and analyzed in order to identify thedifferences in their performances. The methods, which proved to be suitable, arethen further tested using the prototype sensor setup on a loader crane and theperformance results are analyzed in order to make a decision in relation to the twomost suitable methods for the application of the loader crane positioning. Theresults suggested that the two most suitable were the CMRGD and the DCMR. Thepractical design issues relating to this sensor system are highlighted andsuggestions are made in the study. Additionally, possible future work for thisproject is also covered.In the first case for the rotor RPM measurement, the thesis presents themodeling and simulation of the stator-free RPM sensor idea using the Monte Carlomethod, which demonstrated the special features and performance of this sensor.The design aspects of the prototype sensor are described in detail and theprototype is tested on an experimental setup. The conclusions for the stator-freeRPM sensor are then made from the analysis of the experimental results and futurework in relation to this sensor is also proposed.In the second case of the rotor RPM measurement, the thesis presentsanother idea involving the laser mouse RPM sensor and the main focus of thestudy is on the performance characterization of the laser mouse sensor and theverification of the RPM sensor idea. Experiments are conducted using the test setup and results are gathered and analyzed and conclusions are drawn.Possibilities in relation to future work for this laser mouse RPM sensor are alsoprovided.The summary and the conclusion form the final chapter of the thesis andseveral important aspects of the designs relating to both the loader cranepositioning project and the rotor RPM measurement project are discussed.
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| 18. |
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| 19. |
- Imran, Muhammad, et al.
(författare)
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Analysis and Characterization of Embedded Vision Systems for Taxonomy Formulation
- 2013
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - USA : SPIE - International Society for Optical Engineering. - 9780819494290 ; , s. Art. no. 86560J-
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Konferensbidrag (refereegranskat)abstract
- The current trend in embedded vision systems is to propose bespoke solutions for specific problems as each application has different requirement and constraints. There is no widely used model or benchmark which aims to facilitate generic solutions in embedded vision systems. Providing such model is a challenging task due to the wide number of use cases, environmental factors, and available technologies. However, common characteristics can be identified to propose an abstract model. Indeed, the majority of vision applications focus on the detection, analysis and recognition of objects. These tasks can be reduced to vision functions which can be used to characterize the vision systems. In this paper, we present the results of a thorough analysis of a large number of different types of vision systems. This analysis led us to the development of a system’s taxonomy, in which a number of vision functions as well as their combination characterize embedded vision systems. To illustrate the use of this taxonomy, we have tested it against a real vision system that detects magnetic particles in a flowing liquid to predict and avoid critical machinery failure. The proposed taxonomy is evaluated by using a quantitative parameter which shows that it covers 95 percent of the investigated vision systems and its flow is ordered for 60 percent systems. This taxonomy will serve as a tool for classification and comparison of systems and will enable the researchers to propose generic and efficient solutions for same class of systems.
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| 20. |
- Imran, Muhammad, et al.
(författare)
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Architecture Exploration Based on Tasks Partitioning Between Hardware, Software and Locality for a Wireless Vision Sensor Node
- 2012
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Ingår i: International Journal of Distributed Systems and Technologies. - IGI Global, USA. : IGI Global. - 1947-3532 .- 1947-3540. ; 3:2, s. 58-71
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Tidskriftsartikel (refereegranskat)abstract
- Wireless Vision Sensor Networks (WVSNs) is an emerging field which consists of a number of Visual Sensor Nodes (VSNs). Compared to traditional sensor networks, WVSNs operates on two dimensional data, which requires high bandwidth and high energy consumption. In order to minimize the energy consumption, the focus is on finding energy efficient and programmable architectures for the VSN by partitioning the vision tasks among hardware (FPGA), software (Micro-controller) and locality (sensor node or server). The energy consumption, cost and design time of different processing strategies is analyzed for the implementation of VSN. Moreover, the processing energy and communication energy consumption of VSN is investigated in order to maximize the lifetime. Results show that by introducing a reconfigurable platform such as FPGA with small static power consumption and by transmitting the compressed images after pixel based tasks from the VSN results in longer battery lifetime for the VSN.
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