High-speed weight estimation of whole herring (Clupea harengus) using 3D machine vision

Abstract: Weight is an important parameter by which the price of whole herring (Clupea harengus) is determined. Current mechanical weight graders are capable of a high throughput but have a relatively low accuracy. For this reason, there is a need for a more accurate high‐speed weight estimation of whole herring. A 3‐dimensional (3D) machine vision system was developed for high‐speed weight estimation of whole herring. The system uses a 3D laser triangulation system above a conveyor belt moving at a speed of 1000 mm/s. Weight prediction models were developed for several feature sets, and a linear regression model using several 2‐dimensional (2D) and 3D features enabled more accurate weight estimation than using 3D volume only. Using the combined 2D and 3D features, the root mean square error of cross‐validation was 5.6 g, and the worst‐case prediction error, evaluated by cross‐validation, was ±14 g, for a sample (n = 179) of fresh whole herring. The proposed system has the potential to enable high‐speed and accurate weight estimation of whole herring in the processing plants. Practical Application: The 3D machine vision system presented in this article enables high‐speed and accurate weight estimation of whole herring, thus enabling an increase in profitability for the pelagic primary processors through a more accurate weight grading.     

Repeated surface registration for on-line use

We consider the problem of matching sets of 3D points from a measured surface to the surface of a corresponding computer-aided design (CAD) object. The problem arises in the production line where the shape of the produced items is to be compared on-line with its pre-described shape. The involved registration problem is solved using the iterative closest point (ICP) method. In order to make it suitable for on-line use, i.e., make it fast, we pre-process the surface representation of the CAD object. A data structure for this purpose is proposed and named Distance Varying Grid tree. It is based on a regular grid that encloses points sampled from the CAD surfaces. Additional finer grids are added to the vertices in the grid that are close to the sampled points. The structure is efficient since it utilizes that the sampled points are distributed on surfaces, and it provides fast identification of the sampled point that is closest to a measured point. A local linear approximation of the surface is used for improving the accuracy. Experiments are done on items produced for the body of a car. The experiments show that it is possible to reach good accuracy in the registration and decreasing the computational time by a factor 700 compared with using the common kd-tree structure.     

Increased onset temperature of expansion in thermally expandable microspheres through combination of crosslinking agents

Free‐radical suspension polymerization was used to synthesize thermally expandable microspheres (TEMS) in which a poly(acrylonitrile‐co‐methacrylonitrile) shell encapsulates isooctane. TEMS were prepared with 1,4‐butanediol dimethacrylate (BDDMA), in combination with 1,4‐butanediol divinyl ether (BDDVE), diallyl carbonate (DAC), or allyl methacrylate, as crosslinkers. It was found that a significant increase in the onset temperature of expansion (T_start) could be obtained when a combination of BDDMA and BDDVE or DAC was used, compared to when only BDDMA was used as crosslinker. The expansion capacity of the TEMS was excellent when BDDMA and DAC were combined. One benefit of the increased T_start was demonstrated when poly(vinyl chloride)‐plastisols containing TEMS could be cured at higher temperatures without premature expansion. The differences in expansion obtained with different combinations of crosslinkers originate from the difference in reactivity of the vinyl‐functionalities of the crosslinkers, which regulate the incorporation of the crosslinker into the polymer and thereby, the mechanical properties of the microsphere shell. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Thermal properties and transition studies of multi-wall carbon nanotube/nylon-6 composites

Transition behavior and thermal properties of a multi-wall carbon nanotube (MWCNT)/nylon-6 composite (P-composite) made by in situ polymerization and subsequently structurally modified by high-pressure–high-temperature treatment have been established. The thermal conductivity (κ) of nylon-6 improved ∼27% by the addition of 2.1 wt.% MWCNT filler simultaneously as the heat capacity per unit volume decreased ∼22% compared with that of nylon-6 at 1 atm and 298 K. Moreover, the MWCNT filler raises the glass transition temperature (T_g) of nylon-6, but the pressure dependence of T_g remains unchanged. A model for κ indicates that the interfacial thermal resistance between the MWCNT filler and the nylon-6 matrix decreases 20% up to 1 GPa and most significantly above 0.8 GPa. P-composite was structurally modified by a sluggish cold-crystallization transition at 1.0 GPa, 530 K, which further increased κ by as much as ∼37% as the crystallinity of nylon-6 improved from 31% to 58% with a preferred crystal orientation and increased crystal size.     

Span-Dependent Distributions of the Bending Strength of Spruce Timber

Tests data of bending strengths of a large number of timber beams of different spans obtained at the Swedish Institute for Wood Technology Research reveal a statistical structure that can be represented in a simple probabilistic model of series system type. A particular feature of the data from one of the large test series is that unintentionally the data became randomly censored upwards. This censoring of the data rules out both the moment estimation method and the maximum likelihood method. Instead valid parameter estimates can be obtained by maximizing the posterior density defined as the likelihood function multiplied by a suitably chosen noninformative prior density (MP method). Subsequently using bias factors assessed by simulation ensures that the corrected MP estimates are unbiased. A closed form analytical expression for the distribution function of the bending strength of a beam with any given number of defect clusters follows from the obtained distribution model for the bending strength of the random single defect cluster. The empirical distribution function of bending test results for a sample of beams with two defect clusters is well predicted, and for long beams with several defect clusters the same is the case in the lower tail up to at least about the 50% probability level.     

Aktuelle Aspekte der Eisenbahnbetriebsführung — das Betriebsführungssystem ALINET von Alcatel

Liberalization of the European railway transport system and the thus obliged discrimination-free entry to the railway network create new basic conditions for railway operational traffic management. State-of-the-art signaling and train control systems standardized Europe-wide are the basis for a maximum amount of safety and reliability. With ALINET, the extensive management operational system of Alcatel, a corresponding platform is available for the optimized traffic control of railway infrastructure.     

Downstream natural gas in Europe—High hopes dashed for upstream oil and gas companies

Access for independents to retail gas markets was a central concern in European policy reform efforts in the 1990s. Upstream oil and gas companies reacted with strategic intentions of forward integration. By late 2004, forward integration was still weak, however. An important explanation of the gap between announced strategic re-orientation and actual strategy implementation lies in the political failure of EU member states to dismantle market barriers to entry for independents. Variations between companies in downstream strategy implementation are explained by variations in business opportunities and internal company factors.     

Availability, reliability and downtime of systems with repairable components

Closed-form expressions are derived for the steady-state availability, mean rate of failure, mean duration of downtime and lower bound reliability of a general system with randomly and independently failing repairable components. Component failures are assumed to be homogeneous Poisson events in time and repair durations are assumed to be exponentially distributed. The results are expressed in terms of the mean rates of failure and mean durations of repair of the individual components. Closed-form expressions are also derived for the rates of change of the various probabilistic system performance measures with respect to the mean rate of failure and the mean duration of repair of each component. These expressions provide a convenient framework for identifying important components within the system and for decision-making aimed at upgrading the system availability or reliability, or reducing the mean duration of system downtime. Example applications to an electrical substation system demonstrate the use of the formulas developed in the paper.