Wood inspection with non-supervised clustering

Abstract. The appearance of sawn timber has huge natural variations that the human inspector easily compensates for mentally when determining the types of defects and the grade of each board. However, for automatic wood inspection systems these variations are a major source for complication. This makes it difficult to use textbook methodologies for visual inspection. These methodologies generally aim at systems that are trained in a supervised manner with samples of defects and good material, but selecting and labeling the samples is an error-prone process that limits the accuracy that can be achieved. We present a non-supervised clustering-based approach for detecting and recognizing defects in lumber boards. A key idea is to employ a self-organizing map (SOM) for discriminating between sound wood and defects. Human involvement needed for training is minimal. The approach has been tested with color images of lumber boards, and the achieved false detection and error escape rates are low. The approach also provides a self-intuitive visual user interface. Received: 16 December 2000 / Accepted: 8 December 2001 Correspondence to: O. Silvén     

The biological leaching of an auriferous pyrite ore

The oxidation of an auriferous pyrite ore sample was evaluated in biological leaching experiments for subsequent gold recovery via cyanidation. In batch cultures, organisms derived from the mine site oxidized pyrite and ferrous iron at pH values as low as pH 0.6. The recovery of gold was variable in shake flask experiments. In stirred tank bioreactor leaching, gold recovery was proportional to the extent of iron dissolution by bioleaching. The leaching of arsenic from the sample was also directly proportional to iron dissolution.     

一种改进的基于二元统计的HMM分词算法

中文分词是中文信息处理的基础。基于二元统计的HMM中文分词算法表现良好,但也存在易将包含常用介、副词的词进行误拆分的问题。改进的分词算法运用逆向最大匹配的思想,在计算粗分集权重的过程中,考虑了分词的词长及词序对正确切分的有利影响。该算法首先计算出二元统计粗分模型有向边的权值,然后根据词长修定权值,最后运用最短路径法求出分词结果。实验结果表明,该算法有效的解决了过分拆分的问题,分词效果良好。     

The Nile Basin in a Global Perspective

Abstract

The Nile brings virtually no water to the sea. The mighty basin with 1/10 of Africa's land area and 1/3 of its population, has only 1/16 of its water. The riparian countries use practically all of the Nile's water and they face increasing challenges in terms of environmental degradation, food security, and socioeconomic development. The geopolitical situation blocks the integrated development of water resources in the basin scale, yet the political environment may be improving. The Nile basin is among the most critical regions of the world in terms of water resources development. In this article, the trends of the major driving forces within the basin countries—population, urbanization, climate, agriculture, economy, human resources, and governance—are scrutinized from the viewpoint of their impacts on water resources and their management. A comparison is made to four other critical macroregions: China, South Asia, Southeast Asia, and West Africa.     

Framework for Sustainable Food Packaging Design

The environmental impacts of packages have been found to be relatively small compared with the food items they contain. Furthermore, from the environmental and operational point of view, the most significant task of the package is to protect the product, which is important to acknowledge in the packaging design process. This study introduces a guiding framework for designing sustainable food packaging. In this approach, the entire life cycle of the product–package combination is taken into consideration. The emphasis is on the prevention of food losses in packaging design as a major environmental criterion. Consideration of the properties of both the package and the product itself when designing the final package will lead to a better end result with smaller product losses and environmental impacts. By using different assessment methods in the different stages of the packaging design, the sustainability of the package can be enhanced. The decision making of the packaging designer is facilitated with methods that are introduced step by step and in a certain order that will also allow for corrective measures through back‐loops in the design process. The purpose is to integrate sustainability aspects at all stages firmly into the design process. Copyright © 2012 John Wiley & Sons, Ltd.     

Performance tuning and sparse traversal technique for a cell‐based fetch length algorithm on a GPU

For determining distances (fetch lengths) from points to polygons in a two‐dimensional Euclidean plane, cell‐based algorithms provide a simple and effective solution. They divide the input area into a grid of cells that cover the area. The objects are stored into the appropriate cells, and the resulting structure is used for solving the problem. When the input objects are distributed unevenly or the cell size is small, most of the cells may be empty. The representation is then called sparse. In the method proposed in this work, each cell contains information about its distance to the nonempty cells. It is then possible to skip over several empty cells at a time without memory accesses. A cell‐based fetch length algorithm is implemented on a graphics processing unit (GPU). Because control flow divergence reduces its performance, several methods to reduce the divergence are studied. While many of the explicit attempts turn out to be unsuccessful, sorting of the input data and sparse traversal are observed to greatly improve performance: compared with the initial GPU implementation, up to 45‐fold speedup is reached. The speed improvement is greatest when the map is very sparse and the points are given in a random order. Copyright © 2015 John Wiley & Sons, Ltd.     

A rheo-optical apparatus for real time kinetic studies on shear-induced alignment of self-assembled soft matter with small sample volumes

In soft materials, self-assembled nanoscale structures can allow new functionalities but a general problem is to align such local structures aiming at monodomain overall order. In order to achieve shear alignment in a controlled manner, a novel type of rheo-optical apparatus has here been developed that allows small sample volumes and in situ monitoring of the alignment process during the shear. Both the amplitude and orientation angles of low level linear birefringence and dichroism are measured while the sample is subjected to large amplitude oscillatory shear flow. The apparatus is based on a commercial rheometer where we have constructed a flow cell that consists of two quartz teeth. The lower tooth can be set in oscillatory motion whereas the upper one is connected to the force transducers of the rheometer. A custom made cylindrical oven allows the operation of the flow cell at elevated temperatures up to 200 degrees C. Only a small sample volume is needed (from 9 to 25 mm(3)), which makes the apparatus suitable especially for studying new materials which are usually obtainable only in small quantities. Using this apparatus the flow alignment kinetics of a lamellar polystyrene-b-polyisoprene diblock copolymer is studied during shear under two different conditions which lead to parallel and perpendicular alignment of the lamellae. The open device geometry allows even combined optical/x-ray in situ characterization of the alignment process by combining small-angle x-ray scattering using concepts shown by Polushkin et al. [Macromolecules 36, 1421 (2003)].     

Optimised selection of new protective coatings for biofuel boiler applications

Using biofuels in power and CHP boilers can pose a challenge for materials performance. Formation of deposits containing e.g. potassium, sulphur, calcium, sodium, and chlorine can result in severe corrosion of conventional steels and alloys at relatively modest temperatures. Given suitable component design and fabrication facilities, coatings may be considered to protect the fireside surfaces. This paper aims to present a systematic approach to the design and selection criteria for protective coatings of boilers. The approach includes modelling of the process and surface conditions, optimisation of the coating process and structure, and performance validation in the laboratory and plant scales. The applied examples have included iron and nickel based HVOF and arc sprayed coatings subjected to verification field testing in boiler testing under aggressive biofuel conditions. The coatings have shown good corrosion resistance in both laboratory tests and long‐term harsh field tests. The paper discusses the used approach for finding a suitable and cost effective coating for biofuel boiler applications. The paper gives test results from microstructural, corrosion resistance and field testing experience for the selected coatings.