Lule University of Technology
Lule University of Technology
Borch D.Z.,Lule University of Technology |
Sundberg J.,KTH Royal Institute of Technology
Journal of Voice | Year: 2011
This investigation aims at describing voice function of four nonclassical styles of singing, Rock, Pop, Soul, and Swedish Dance Band. A male singer, professionally experienced in performing in these genres, sang representative tunes, both with their original lyrics and on the syllable /pae/. In addition, he sang tones in a triad pattern ranging from the pitch Bb2 to the pitch C4 on the syllable /pae/ in pressed and neutral phonation. An expert panel was successful in classifying the samples, thus suggesting that the samples were representative of the various styles. Subglottal pressure was estimated from oral pressure during the occlusion for the consonant [p]. Flow glottograms were obtained from inverse filtering. The four lowest formant frequencies differed between the styles. The mean of the subglottal pressure and the mean of the normalized amplitude quotient (NAQ), that is, the ratio between the flow pulse amplitude and the product of period and maximum flow declination rate, were plotted against the mean of fundamental frequency. In these graphs, Rock and Swedish Dance Band assumed opposite extreme positions with respect to subglottal pressure and mean phonation frequency, whereas the mean NAQ values differed less between the styles. © 2011 The Voice Foundation.
Karlsson J.,Lule University of Technology |
Kaplan A.F.H.,Lule University of Technology
Applied Surface Science | Year: 2011
For fibre laser welding of an eccentric corner joint, the quality of the resulting weld cross section was studied with respect to the dependence on process parameters like lateral laser beam alignment, beam inclination, focal plane position or welding speed. The complex load situation of the support beamer was simplified to bending of one corner. Due to fatigue load, the weld properties causing the peak stress are essential, in particular the top and root shape of the weld cross section. For the parameters varied, the resulting shapes were categorized into different top and root classes, determined by certain key dimensions, considering also welding defects like undercuts. The shapes are boundary conditions for Finite Element Analysis of the joint under load for quantitative comparative analysis of the maximum stress. As two high strength steel grades were joined, the hardness transition across the weld was of interest, too. High speed imaging of the weld pool surface shape provided additional information on the relation between the parameter input and quality output. The different trends identified were discussed and guidelines were derived. As the systematic documentation of results is unsatisfactory in welding, a new method was developed and applied for the first time, called the Matrix Flow Chart. It enables an illustrative view on the resulting welding trends in a combined manner and is extendable by other researchers. © 2010 Elsevier B.V.
Castano Arranz M.,Lule University of Technology |
Birk W.,Lule University of Technology
Journal of Process Control | Year: 2012
The selection of the structure of a controller in large scale industry processes usually requires extensive process knowledge. The aim of this paper is to report new results on recently suggested methods for the analysis of complex processes. These methods aid the designers in comprehending a process by representing structural and functional relationships from actuators and process disturbances to measured or estimated variables. The methods are formulated in a flexible framework based on graph theory, which can also be used for closed-loop analysis. Additionally, the sensitivity of the methods to scaling and time delays are discussed and resolved. It is also proposed how filtering can be used to restrict the analysis to a frequency region of interest. The feasibility of the methods is shown by the use of three case studies. A quadruple tank process is used to exemplify the methods and their use. Then the methods are applied on a real-life process, the stock preparation plant of a pulp and paper mill. The third study case analyzes a previously published example in closed loop. It is shown that the methods can be used to take efficient decisions on decentralized and sparse control structures, as well as assessing the channel interactions in a closed-loop system. © 2011 Elsevier Ltd. All Rights Reserved.
Awe S.A.,Lule University of Technology |
Sandstrom K.,Lule University of Technology
Minerals Engineering | Year: 2010
Removal of impurity elements in copper metallurgy is one of the major problems encountered today since pure copper ore reserves are becoming exhausted and the resources of unexploited ores often contain relatively high amounts of impurity elements like antimony, arsenic, mercury and bismuth, which need to be eliminated. The present work is aimed at pre-treating a tetrahedrite rich complex sulphide concentrate by selective dissolution of the impurities, therefore, upgrading it for pyrometallurgical processing. To accomplish this, dissolution of antimony and arsenic by an alkaline sulphide lixiviant from the concentrate were investigated. The lixiviant proved selective and effective to dissolve these impurity elements from the concentrate with good recoveries. Further investigations on the factors influencing the leaching efficiency of the lixiviant were studied. The parameters considered were sulphide ion and hydroxide ion concentrations, mineral particle size, reaction temperature and leaching time. Analysis of the leach residue indicates that copper content of tetrahedrite has transformed into copper sulphides with the average chemical formula Cu1.64S. The grade and economic value of the concentrate were improved greatly after sulphide treatment, and therefore, suitable as a feedstock for smelting. The impurities have been reduced to low levels which are tolerable in the smelting furnace and consequently reduce both the treatment and environmental problem encountered when such concentrate is processed pyrometallurgically. © 2010 Elsevier Ltd. All rights reserved.
Alzghoul A.,Lule University of Technology |
Lofstrand M.,Lule University of Technology
Computers and Industrial Engineering | Year: 2011
Improving industrial product reliability, maintainability and thus availability is a challenging task for many industrial companies. In industry, there is a growing need to process data in real time, since the generated data volume exceeds the available storage capacity. This paper consists of a review of data stream mining and data stream management systems aimed at improving product availability. Further, a newly developed and validated grid-based classifier method is presented and compared to one-class support vector machine (OCSVM) and a polygon-based classifier. The results showed that, using 10% of the total data set to train the algorithm, all three methods achieved good (>95% correct) overall classification accuracy. In addition, all three methods can be applied on both offline and online data. The speed of the resultant function from the OCSVM method was, not surprisingly, higher than the other two methods, but in industrial applications the OCSVMs' comparatively long time needed for training is a possible challenge. The main advantage of the grid-based classification method is that it allows for calculation of the probability (%) that a data point belongs to a specific class, and the method can be easily modified to be incremental. The high classification accuracy can be utilized to detect the failures at an early stage, thereby increasing the reliability and thus the availability of the product (since availability is a function of maintainability and reliability). In addition, the consequences of equipment failures in terms of time and cost can be mitigated. © 2010 Elsevier Ltd. All rights reserved.
Andersons J.,University of Latvia |
Joffe R.,Lule University of Technology
Composites Part A: Applied Science and Manufacturing | Year: 2011
Unidirectional orientation of natural fibers in a polymer composite ensures the highest efficiency of reinforcement. Flax fiber reinforcement is discontinuous due to limited fiber length and heterogeneous due to the presence of elementary fibers and their bundles. In order to assess the upper limit of tensile strength of such slightly misoriented, nominally UD natural fiber composite, a statistical strength model of continuous UD fiber reinforced composites is applied. It is found that the experimental strength of UD flax composites, produced from rovings or manually aligned fibers, approaches the theoretical limit only at relatively low fiber volume fraction ca. 0.2, being markedly below it at higher fiber content. © 2011 Elsevier Ltd. All rights reserved.
Desautels P.,Lule University of Technology |
Berthon P.,Bentley University
Journal of Strategic Information Systems | Year: 2011
The portable computer or notebook has become an integral and even essential aspect of modern life. Year-in-year its price to the consumer falls while its performance grows, yet recent analysis suggests that pound-for-pound its environmental costs are amongst the highest of any product on the planet. In this paper we explore the market price of "sustainable" notebooks. Drawing on the framework of the 'tragedy of the commons' we postulate that as manufacturers shift costs away from the commons to comply with sustainability standards, the cost to the consumer will inevitably rise. We test our hypothesis by comparing the prices of EPEAT Gold certified notebooks with uncertified portable computers. The results are discussed, alternative hypotheses explored and further research outlined. © 2010 Elsevier B.V. All rights reserved.
Brchner J.,Chalmers University of Technology |
Olofsson T.,Lule University of Technology
Journal of Construction Engineering and Management | Year: 2012
A 30-year retrospective analysis of resource use in a range of new construction and repair projects reveals insignificant productivity increase when applying traditional narrow measures, as shown in a case study of beam bridges. It appears as necessary to estimate hidden quality changes in both outputs and inputs. Changes in government regulations, in specifications, and the development of nonprice criteria for contract award emerge as important. Schemes for benchmarking the performance of construction projects as well as life-cycle analyses suggest that customer risk aversion and effects on customer productivity should be taken into account. The outcome is a set of measurements that can be applied to the selection of any type of proposed new construction or repair technology innovation according to their potential impact on industry productivity. © 2012 American Society of Civil Engineers.
Rownaghi A.A.,Lule University of Technology |
Rezaei F.,Lule University of Technology |
Hedlund J.,Lule University of Technology
Microporous and Mesoporous Materials | Year: 2012
In this study, an efficient procedure for controllable synthesis of uniform mesoporous ZSM-5 single crystals with various crystal architectures and high mesoporosity was developed. Compared with conventional ZSM-5 catalyst, mesoporous ZSM-5 single crystals synthesized by this method exhibited significantly higher external surface area and larger mesopore volume than conventional one. The catalytic performance of mesoporous zeolites were evaluated in the conversion of methanol to hydrocarbons using a fixed-bed reactor operating at 370 °C, atmospheric pressure and weight hourly space velocities (WHSV) of 0.16-6.58 h -1. By controlling the ZSM-5 synthesis procedure, the activity and stability of the ZSM-5 catalyst in the conversion of methanol to gasoline-range hydrocarbons can be favorably tuned. We also found that mesoporosity plays a crucial role in catalyst stability. Good correlation was observed between catalyst lifetime and mesoporosity. While the catalyst activity is related to the acid site density, the catalyst stability (deactivation rate) correlates with the measured surface ratio of BET and external surface area (S BET/S meso). The novel ZSM-5 catalyst exhibited improved stability due to the faster removal of products with shorter diffusion path-length and lower coke formation. The obtained results indicated that the novel mesoporous ZSM-5 catalyst containing relatively large pores (mostly mesopores) enhances reaction yield towards gasoline-range hydrocarbons. It is therefore concluded that the relatively slow deactivation rate (coke formation) of novel mesoporous ZSM-5 single crystals catalyst makes this zeolite the preferred catalyst for the conversion of methanol to gasoline-range hydrocarbons at mild conditions. © 2011 Elsevier Inc. All rights reserved.
Lukaszewska E.,Lule University of Technology |
Fragiacomo M.,University of Sassari |
Johnsson H.,Lule University of Technology
Journal of Structural Engineering | Year: 2010
This paper describes tests on a novel composite floor system constructed by connecting prefabricated concrete slabs to timber joists. Seven types of shear connectors have been developed and tested: lag screws, either alone or combined with a notch cut from each timber joist; metal plates embedded in the concrete slab and either nailed or glued to the joists; dowels embedded in the concrete and glued to the timber; and toothed metal plates embedded in the concrete and pressed into the timber. Four-point bending tests to failure were performed on five, full-scale, 4.8 m long specimens connected with lag screws or metal plates nailed to the timber. Values of deflection and relative slip between the concrete slab and the timber obtained in these tests showed high correspondence with values obtained from a uniaxial finite element model developed for nonlinear analyses of composite beams. The model was also used to perform a numerical analysis to failure of composite beams with the other four connection systems that were developed but not tested on full-scale specimens. The outcomes of the experimental tests and numerical analyses show that the newly developed system can provide good structural performance, especially if connections with coach screws and notches in the timber are used. The economic advantages of prefabrication and the possibility to disassemble the structure and reuse the timber beams and concrete panels at the end of the service life make the proposed floor system very promising. © 2010 ASCE.