1,371 research outputs found
Fuel pellet production from reed canary grass
No full textThis thesis focuses on two main areas: methods for assessing regional supply potentials of reed canary grass (Phalaris arundinacea L.) (RCG); and process technology for the production of high-quality RCG pellets. Partial equilibrium modelling, incorporating a break-even price approach, was used to examine supply potentials for RCG in Västerbotten County, northern Sweden. A remote sensing method, using black and white orthophoto interpretation, was developed, by which abandoned fields with low preparation costs (on average 173 SEK (ha)-1) could be distinguished from fields with high preparation costs (on average 3990 SEK (ha)-1). Based on the assumptions made, RCG production would predominantly be viable in the coastal area of Västerbotten County, and production equal to 1.3 TWh could be supplied at a farmgate fuel price of 116 SEK MW-1h-1. Pelletizing RCG allows it to be transported, stored and handled more easily. To determine the optimum conditions for RCG pelletizing, experiments were performed in an experimental design incorporating the factors: moisture content, steam addition, raw material density, and die temperature. Pre-compaction of the raw material was an efficient method for avoiding uneven pellet production. Through multiple response optimization, process settings were identified for the production of RCG pellets with a bulk density ≥ 650 kg m-3 and a durability ≥ 97.5%. To clarify the underlying mechanisms in the pelletizing process, the influences of moisture content and normal stress on the kinematic wall friction properties of RCG powder were studied. A steep increase in the kinematic wall friction with increasing normal stress was found in the normal stress interval 50-150 MPa. Multiple linear regression modelling of kinematic wall friction measurements at high normal stresses (65 to 376 MPa) revealed a local maximum at moisture contents of 13–16% and normal stresses of 150–225 MPa. Kinematic wall friction and pellet durability maxima occurred in overlapping moisture content ranges; it was, therefore, hypothesised that the two properties were correlated
The numerical modelling of rockbolts in geomechanics by finite element methods
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 15/03/1999.In tunnel excavation, the use of rockbolts has long been a popular means of reinforcement in rock masses to prevent the rock opening from caving in. The idea has evolved from the earliest form of rockbolt made of wood to the more up-to-date form of pre-tensioned or grouted steel rockbolts.
A major breakthrough in the design of rockbolt models was made by Aydan (1989). This rockbolt element was modelled in coupled form, with one sub-element representing the steel bolt, and the other sub-element the grout. This representation was necessary to model the complex action in the continuous rock mass near the joint.
In elasticity problems, the large displacement formulation of a beam element is derived from the fundamental theory, and the bending phenomenon of a thin rod is analysed by the finite element discretizations of the bar elements and the beam elements. Experiments show that the deformation characteristics of the latter representation resemble a more realistic life behaviour. Based on this finding, this thesis proposes a modification to Aydan's two-dimensional rockbolt element, with the beam elements discretising the steel bolt.
The different mechanical responses of a perfectly elastic rockbolt are considered, and the large displacement formulation of the new rockbolt element is derived by combining those of Aydan's rockbolt element and the beam element.
The mechanics of the Aydan element and the new rockbolt element are described, and their performances are compared in an identical situation. It is found that in the two two-dimensional examples used in this thesis, the modified element ensures the continuity of curvature of the rockbolt, and in general, can act as support across a discontinuity or joint between rock masses well.
In conjunction with the displacement method in the finite element procedures, a conventional iteration solution procedure is first described to solve the nonlinear incremental stiffness equation. However, it is found that this procedure is cumbersome, and requires a large amount of comptutations. Some limited storage quasi-Newton minimization algorithms are considered as an alternative
Ecology of the Festuca Grassland in Central Saskatchewan
No full textFor some time it has been realized that the grassland occuring in the 'park belt' or 'aspen grove region' bounding the Canadian prairies on the north, and forming the transition between it and the boreal forest, does not consist merely of extensions of the adjacent grassland communities (true prairie or mixed prairie) among the patches of woodland which occur in that region; but is characterized by a different group of dominant grasses from those occuring elsewhere in North America.
Although other investigators have mentioned this fact and written about the flora in other parts of the region, their data have been based largely on methods of estimation chiefly of a qualitative nature. In view of this, it was thought that an ecological survey based on quantitative methods might provide a better basis for classifying the vegetation of the area.
Accordingly, while being employed as an assistant in the Department of Plant Ecology of the University of Saskatchewan the author was given the opportunity, under the supervision of Dr. R.T. Coupland, to carry out investigations in those parts of the aspen grove region north and northwest of Saskatoon.
The author is considerably indebted to Dr. B.W. Currie of the Physics Department, for furnishing data on the climate of the area of research, and to Mr. H.C. Moss and his assistants, of the Saskachewan Soil Survey, who kindly undertook to examine and report on the soil samples which were collected in several of the sites studied. The author also wishes to express his gratitide to Mr. Jack F. Alex and Mr. W. Budz of the Department of Plant Ecology, who assisted greatly in both the field and laboratory work for this project. The financial assistance of the Saskatchewan Agricultural Research Foundation, which made this study possible, is also appreciated.
The author experienced a great deal of difficulty as a result of unfamiliarity with the topography, in particular with the vegetation of the plants, since he is more accustomed to the mountains and forests of British Columbia. Many problems of identifications were encountered in dealing with the wealth of species of grasses and composites, as well as problems of relationship between the communities found in certain locations and their topographical situation
TNFAIP3 (A20) is a tumor suppressor gene in Hodgkin lymphoma and primary mediastinal B cell lymphoma
No full textProliferation and survival of Hodgkin and Reed/Sternberg (HRS) cells, the malignant cells of classical Hodgkin lymphoma (cHL), are dependent on constitutive activation of nuclear factor {kappa}B (NF-{kappa}B). NF-{kappa}B activation through various stimuli is negatively regulated by the zinc finger protein A20. To determine whether A20 contributes to the pathogenesis of cHL, we sequenced TNFAIP3, encoding A20, in HL cell lines and laser-microdissected HRS cells from cHL biopsies. We detected somatic mutations in 16 out of 36 cHLs (44%), including missense mutations in 2 out of 16 Epstein-Barr virus–positive (EBV+) cHLs and a missense mutation, nonsense mutations, and frameshift-causing insertions or deletions in 14 out of 20 EBV– cHLs. In most mutated cases, both TNFAIP3 alleles were inactivated, including frequent chromosomal deletions of TNFAIP3. Reconstitution of wild-type TNFAIP3 in A20-deficient cHL cell lines revealed a significant decrease in transcripts of selected NF-{kappa}B target genes and caused cytotoxicity. Extending the mutation analysis to primary mediastinal B cell lymphoma (PMBL), another lymphoma with constitutive NF-{kappa}B activity, revealed destructive mutations in 5 out of 14 PMBLs (36%). This report identifies TNFAIP3 (A20), a key regulator of NF-{kappa}B activity, as a novel tumor suppressor gene in cHL and PMBL. The significantly higher frequency of TNFAIP3 mutations in EBV– than EBV+ cHL suggests complementing functions of TNFAIP3 inactivation and EBV infection in cHL pathogenesis
Phi Chi 1923
No full textM.A. Welbes, T.Y. Dorwart, E.F. Condon, Ed. A. Hier, A. Danielson, E. Vieria, E.E. Beechwood, G.A. Bendlage, H.J. Arnold, D.L. Delehant, H.C. Wise, F.E. Tooney, M.J. Ryan, P. Reed, A.J. Mayer, H.W. Maly, A.E. Mailliard, Herbert M. Every, E.A. Lebold, M.E. Beitenman, J.R. Primasing, R.T. Rohwer, J.L. Keste
Coordination in an Adaptive Traffic Signal Control System
No full textCoordination between the intersections is used in traffic signal control for quite a long time. The objective of this thesis is to determine how beneficial network coordination is in an adaptive traffic signal control system that follows the multi-agent approach. As part of the research: Simulation results show that coordination in a multi-agent controller can reduce average delay of the users on the network depending on the average demand. The best performing coordination measure is platooning cars on the main streams at the first intersection of the arterial. This provide time for the downstream intersections to serve side streams and ensured that the main stream is not stopped at the downstream intersections on the arterial. The tested coordination measures reduced delay with 10% compared to the original settings.Transport and PlanningTransport & PlanningCivil Engineering and Geoscience
The implementation of a system description language and its semantic functions
No full textElectrical Engineering, Mathematics and Computer Scienc
Distributed Gaussian Process Hyperparameter Optimization for Multi-Agent Systems
No full textGaussian Process (GP) is a flexible non-parametric method which has a wide variety of applications e.g., field estimation using multi-agent systems. However, the training of the hyperparameters suffers from high computational complexity. Recently, distributed hyperparameter optimization with proximal gradients has been proposed to reduce complexity, however only for a network with a central station. In this work, exploiting edge-based constraints, we propose two fully-distributed algorithms pxADMMfd and pxADMMfd,fast for a network of multi-agent systems, which do not rely on a central station. In addition, asynchronous versions of the algorithms are also proposed to reduce the synchronization overhead in heterogeneous networks. Simulations are conducted for a field estimation problem, using both artificial, and real-world datasets, which show that the proposed fully-distributed algorithms successfully converge, at the cost of an increased number of iterations.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Signal Processing System
RadioAstron gravitational redshift experiment: status update
No full textA test of a cornerstone of general relativity, the gravitational redshift effect, is currently being conducted with the RadioAstron spacecraft, which is on a highly eccentric orbit around Earth. Using ground radio telescopes to record the spacecraft signal, synchronized to its ultra-stable on-board H-maser, we can probe the varying flow of time on board with unprecedented accuracy. The observations performed so far, currently being analyzed, have already allowed us to measure the effect with a relative accuracy of 4 × 10−4 . We expect to reach 2.5×10−5 with additional observations in 2016, an improvement of almost a magnitude over the 40-year old result of the GP-A mission
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