WorldWideScience

Sample records for dti parameter optimisation

  1. Glaucoma severity affects diffusion tensor imaging (DTI) parameters of the optic nerve and optic radiation

    Energy Technology Data Exchange (ETDEWEB)

    Sidek, S. [Department of Biomedical Imaging, University Malaya, Research Imaging Centre, Faculty of Medicine, University Malaya (Malaysia); Medical Imaging Unit, Faculty of Medicine, Universiti Teknologi MARA, Selangor (Malaysia); Ramli, N. [Department of Biomedical Imaging, University Malaya, Research Imaging Centre, Faculty of Medicine, University Malaya (Malaysia); Rahmat, K., E-mail: katt_xr2000@yahoo.com [Department of Biomedical Imaging, University Malaya, Research Imaging Centre, Faculty of Medicine, University Malaya (Malaysia); Ramli, N.M.; Abdulrahman, F. [Department of Ophthalmology, Faculty of Medicine, University Malaya, Kuala Lumpur (Malaysia); Tan, L.K. [Department of Biomedical Imaging, University Malaya, Research Imaging Centre, Faculty of Medicine, University Malaya (Malaysia)

    2014-08-15

    Objectives: To evaluate whether MR diffusion tensor imaging (DTI) of the optic nerve and optic radiation in glaucoma patients provides parameters to discriminate between mild and severe glaucoma and to determine whether DTI derived indices correlate with retinal nerve fibre layer (RNFL) thickness. Methods: 3-Tesla DTI was performed on 90 subjects (30 normal, 30 mild glaucoma and 30 severe glaucoma subjects) and the FA and MD of the optic nerve and optic radiation were measured. The categorisation into mild and severe glaucoma was done using the Hodapp–Parrish–Anderson (HPA) classification. RNFL thickness was also assessed on all subjects using OCT. Receiver operating characteristic (ROC) analysis and Spearman's correlation coefficient was carried out. Results: FA and MD values in the optic nerve and optic radiation decreased and increased respectively as the disease progressed. FA at the optic nerve had the highest sensitivity (87%) and specificity (80%). FA values displayed the strongest correlation with RNFL thickness in the optic nerve (r = 0.684, p ≤ 0.001) while MD at the optic radiation showed the weakest correlation with RNFL thickness (r = −0.360, p ≤ 0.001). Conclusions: The high sensitivity and specificity of DTI-derived FA values in the optic nerve and the strong correlation between DTI-FA and RNFL thickness suggest that these parameters could serve as indicators of disease severity.

  2. Glaucoma severity affects diffusion tensor imaging (DTI) parameters of the optic nerve and optic radiation

    International Nuclear Information System (INIS)

    Sidek, S.; Ramli, N.; Rahmat, K.; Ramli, N.M.; Abdulrahman, F.; Tan, L.K.

    2014-01-01

    Objectives: To evaluate whether MR diffusion tensor imaging (DTI) of the optic nerve and optic radiation in glaucoma patients provides parameters to discriminate between mild and severe glaucoma and to determine whether DTI derived indices correlate with retinal nerve fibre layer (RNFL) thickness. Methods: 3-Tesla DTI was performed on 90 subjects (30 normal, 30 mild glaucoma and 30 severe glaucoma subjects) and the FA and MD of the optic nerve and optic radiation were measured. The categorisation into mild and severe glaucoma was done using the Hodapp–Parrish–Anderson (HPA) classification. RNFL thickness was also assessed on all subjects using OCT. Receiver operating characteristic (ROC) analysis and Spearman's correlation coefficient was carried out. Results: FA and MD values in the optic nerve and optic radiation decreased and increased respectively as the disease progressed. FA at the optic nerve had the highest sensitivity (87%) and specificity (80%). FA values displayed the strongest correlation with RNFL thickness in the optic nerve (r = 0.684, p ≤ 0.001) while MD at the optic radiation showed the weakest correlation with RNFL thickness (r = −0.360, p ≤ 0.001). Conclusions: The high sensitivity and specificity of DTI-derived FA values in the optic nerve and the strong correlation between DTI-FA and RNFL thickness suggest that these parameters could serve as indicators of disease severity

  3. Optimisation of milling parameters using neural network

    Directory of Open Access Journals (Sweden)

    Lipski Jerzy

    2017-01-01

    Full Text Available The purpose of this study was to design and test an intelligent computer software developed with the purpose of increasing average productivity of milling not compromising the design features of the final product. The developed system generates optimal milling parameters based on the extent of tool wear. The introduced optimisation algorithm employs a multilayer model of a milling process developed in the artificial neural network. The input parameters for model training are the following: cutting speed vc, feed per tooth fz and the degree of tool wear measured by means of localised flank wear (VB3. The output parameter is the surface roughness of a machined surface Ra. Since the model in the neural network exhibits good approximation of functional relationships, it was applied to determine optimal milling parameters in changeable tool wear conditions (VB3 and stabilisation of surface roughness parameter Ra. Our solution enables constant control over surface roughness parameters and productivity of milling process after each assessment of tool condition. The recommended parameters, i.e. those which applied in milling ensure desired surface roughness and maximal productivity, are selected from all the parameters generated by the model. The developed software may constitute an expert system supporting a milling machine operator. In addition, the application may be installed on a mobile device (smartphone, connected to a tool wear diagnostics instrument and the machine tool controller in order to supply updated optimal parameters of milling. The presented solution facilitates tool life optimisation and decreasing tool change costs, particularly during prolonged operation.

  4. Optimisation of parameters of DCD for PHWRs

    International Nuclear Information System (INIS)

    Velmurugan, S.; Sathyaseelan, V.S.; Narasimhan, S.V.; Mathur, P.K.

    1991-01-01

    Decontamination formulation based on EDTA, Oxalic acid, Citric acid was evaluated for its efficacy in removing oxide layers of PHWR. An ion exchange system which was specifically suitable for fission product dominated contamination in PHWRs was optimised for the reagent regeneration stage of the decontamination process. An analysis of the nature of the complexed metal species formed in the dissolution process and Electrochemical measurements were employed as a tool to follow the course of oxide removal during the dissolution process. An attempt was made to understand the redeposition behaviour of various isotopes during the decontamination process. SEM and ESCA studies of metal coupons before and after the dissolution process were used to analyse the deposits in the above context. The pick up of DCD reagents on the ion exchangers and material compatibility tests on Carbon steel, Monel-400 and Zircaloy-2 with the decontaminant under the conditions of decontamination experiment are reported. (author)

  5. Parameter Optimisation for the Behaviour of Elastic Models over Time

    DEFF Research Database (Denmark)

    Mosegaard, Jesper

    2004-01-01

    Optimisation of parameters for elastic models is essential for comparison or finding equivalent behaviour of elastic models when parameters cannot simply be transferred or converted. This is the case with a large range of commonly used elastic models. In this paper we present a general method tha...

  6. Optimisation on processing parameters for minimising warpage on side arm using response surface methodology (RSM) and particle swarm optimisation (PSO)

    Science.gov (United States)

    Rayhana, N.; Fathullah, M.; Shayfull, Z.; Nasir, S. M.; Hazwan, M. H. M.; Sazli, M.; Yahya, Z. R.

    2017-09-01

    This study presents the application of optimisation method to reduce the warpage of side arm part. Autodesk Moldflow Insight software was integrated into this study to analyse the warpage. The design of Experiment (DOE) for Response Surface Methodology (RSM) was constructed and by using the equation from RSM, Particle Swarm Optimisation (PSO) was applied. The optimisation method will result in optimised processing parameters with minimum warpage. Mould temperature, melt temperature, packing pressure, packing time and cooling time was selected as the variable parameters. Parameters selection was based on most significant factor affecting warpage stated by previous researchers. The results show that warpage was improved by 28.16% for RSM and 28.17% for PSO. The warpage improvement in PSO from RSM is only by 0.01 %. Thus, the optimisation using RSM is already efficient to give the best combination parameters and optimum warpage value for side arm part. The most significant parameters affecting warpage are packing pressure.

  7. Reducing surface roughness by optimising the turning parameters

    Directory of Open Access Journals (Sweden)

    Senthil Kumar, K.

    2013-08-01

    Full Text Available Modern manufacturers worldwide look for the cheapest quality-manufactured machined components to compete in the market. Good surface quality is desired for the proper functioning of the parts produced. The surface quality is influenced by the cutting speed, feed rate, depth of cut, and many other parameters. In this paper, the Taguchi method a powerful tool to design optimisation for quality is used to find the optimal machining parameters for the turning operation. An orthogonal array, the signal-to-noise (S/N ratio, and the analysis of variance (ANOVA are employed to investigate the machining characteristics of super duplex stainless steel bars using uncoated carbide cutting tools. The effect of machining parameters on surface roughness was discovered. Confirmation tests were conducted at optimal conditions to compare the experimental results with the predicted values.

  8. DTI analysis methods : Voxel-based analysis

    NARCIS (Netherlands)

    Van Hecke, Wim; Leemans, Alexander; Emsell, Louise

    2016-01-01

    Voxel-based analysis (VBA) of diffusion tensor imaging (DTI) data permits the investigation of voxel-wise differences or changes in DTI metrics in every voxel of a brain dataset. It is applied primarily in the exploratory analysis of hypothesized group-level alterations in DTI parameters, as it does

  9. Time varying acceleration coefficients particle swarm optimisation (TVACPSO): A new optimisation algorithm for estimating parameters of PV cells and modules

    International Nuclear Information System (INIS)

    Jordehi, Ahmad Rezaee

    2016-01-01

    Highlights: • A modified PSO has been proposed for parameter estimation of PV cells and modules. • In the proposed modified PSO, acceleration coefficients are changed during run. • The proposed modified PSO mitigates premature convergence problem. • Parameter estimation problem has been solved for both PV cells and PV modules. • The results show that proposed PSO outperforms other state of the art algorithms. - Abstract: Estimating circuit model parameters of PV cells/modules represents a challenging problem. PV cell/module parameter estimation problem is typically translated into an optimisation problem and is solved by metaheuristic optimisation problems. Particle swarm optimisation (PSO) is considered as a popular and well-established optimisation algorithm. Despite all its advantages, PSO suffers from premature convergence problem meaning that it may get trapped in local optima. Personal and social acceleration coefficients are two control parameters that, due to their effect on explorative and exploitative capabilities, play important roles in computational behavior of PSO. In this paper, in an attempt toward premature convergence mitigation in PSO, its personal acceleration coefficient is decreased during the course of run, while its social acceleration coefficient is increased. In this way, an appropriate tradeoff between explorative and exploitative capabilities of PSO is established during the course of run and premature convergence problem is significantly mitigated. The results vividly show that in parameter estimation of PV cells and modules, the proposed time varying acceleration coefficients PSO (TVACPSO) offers more accurate parameters than conventional PSO, teaching learning-based optimisation (TLBO) algorithm, imperialistic competitive algorithm (ICA), grey wolf optimisation (GWO), water cycle algorithm (WCA), pattern search (PS) and Newton algorithm. For validation of the proposed methodology, parameter estimation has been done both for

  10. Optimisation of process parameters on thin shell part using response surface methodology (RSM)

    Science.gov (United States)

    Faiz, J. M.; Shayfull, Z.; Nasir, S. M.; Fathullah, M.; Rashidi, M. M.

    2017-09-01

    This study is carried out to focus on optimisation of process parameters by simulation using Autodesk Moldflow Insight (AMI) software. The process parameters are taken as the input in order to analyse the warpage value which is the output in this study. There are some significant parameters that have been used which are melt temperature, mould temperature, packing pressure, and cooling time. A plastic part made of Polypropylene (PP) has been selected as the study part. Optimisation of process parameters is applied in Design Expert software with the aim to minimise the obtained warpage value. Response Surface Methodology (RSM) has been applied in this study together with Analysis of Variance (ANOVA) in order to investigate the interactions between parameters that are significant to the warpage value. Thus, the optimised warpage value can be obtained using the model designed using RSM due to its minimum error value. This study comes out with the warpage value improved by using RSM.

  11. Pre-segmented 2-Step IMRT with subsequent direct machine parameter optimisation – a planning study

    International Nuclear Information System (INIS)

    Bratengeier, Klaus; Meyer, Jürgen; Flentje, Michael

    2008-01-01

    Modern intensity modulated radiotherapy (IMRT) mostly uses iterative optimisation methods. The integration of machine parameters into the optimisation process of step and shoot leaf positions has been shown to be successful. For IMRT segmentation algorithms based on the analysis of the geometrical structure of the planning target volumes (PTV) and the organs at risk (OAR), the potential of such procedures has not yet been fully explored. In this work, 2-Step IMRT was combined with subsequent direct machine parameter optimisation (DMPO-Raysearch Laboratories, Sweden) to investigate this potential. In a planning study DMPO on a commercial planning system was compared with manual primary 2-Step IMRT segment generation followed by DMPO optimisation. 15 clinical cases and the ESTRO Quasimodo phantom were employed. Both the same number of optimisation steps and the same set of objective values were used. The plans were compared with a clinical DMPO reference plan and a traditional IMRT plan based on fluence optimisation and consequent segmentation. The composite objective value (the weighted sum of quadratic deviations of the objective values and the related points in the dose volume histogram) was used as a measure for the plan quality. Additionally, a more extended set of parameters was used for the breast cases to compare the plans. The plans with segments pre-defined with 2-Step IMRT were slightly superior to DMPO alone in the majority of cases. The composite objective value tended to be even lower for a smaller number of segments. The total number of monitor units was slightly higher than for the DMPO-plans. Traditional IMRT fluence optimisation with subsequent segmentation could not compete. 2-Step IMRT segmentation is suitable as starting point for further DMPO optimisation and, in general, results in less complex plans which are equal or superior to plans generated by DMPO alone

  12. Optimisation of wire-cut EDM process parameter by Grey-based response surface methodology

    Science.gov (United States)

    Kumar, Amit; Soota, Tarun; Kumar, Jitendra

    2018-03-01

    Wire electric discharge machining (WEDM) is one of the advanced machining processes. Response surface methodology coupled with Grey relation analysis method has been proposed and used to optimise the machining parameters of WEDM. A face centred cubic design is used for conducting experiments on high speed steel (HSS) M2 grade workpiece material. The regression model of significant factors such as pulse-on time, pulse-off time, peak current, and wire feed is considered for optimising the responses variables material removal rate (MRR), surface roughness and Kerf width. The optimal condition of the machining parameter was obtained using the Grey relation grade. ANOVA is applied to determine significance of the input parameters for optimising the Grey relation grade.

  13. Analyzing parameters optimisation in minimising warpage on side arm using response surface methodology (RSM)

    Science.gov (United States)

    Rayhana, N.; Fathullah, M.; Shayfull, Z.; Nasir, S. M.; Hazwan, M. H. M.

    2017-09-01

    This paper presents a systematic methodology to analyse the warpage of the side arm part using Autodesk Moldflow Insight software. Response Surface Methodology (RSM) was proposed to optimise the processing parameters that will result in optimal solutions by efficiently minimising the warpage of the side arm part. The variable parameters considered in this study was based on most significant parameters affecting warpage stated by previous researchers, that is melt temperature, mould temperature and packing pressure while adding packing time and cooling time as these is the commonly used parameters by researchers. The results show that warpage was improved by 10.15% and the most significant parameters affecting warpage are packing pressure.

  14. Contrasting brain patterns of writing-related DTI parameters, fMRI connectivity, and DTI–fMRI connectivity correlations in children with and without dysgraphia or dyslexia

    Science.gov (United States)

    Richards, T.L.; Grabowski, T.J.; Boord, P.; Yagle, K.; Askren, M.; Mestre, Z.; Robinson, P.; Welker, O.; Gulliford, D.; Nagy, W.; Berninger, V.

    2015-01-01

    Based on comprehensive testing and educational history, children in grades 4–9 (on average 12 years) were diagnosed with dysgraphia (persisting handwriting impairment) or dyslexia (persisting word spelling/reading impairment) or as typical writers and readers (controls). The dysgraphia group (n = 14) and dyslexia group (n = 17) were each compared to the control group (n = 9) and to each other in separate analyses. Four brain region seed points (left occipital temporal gyrus, supramarginal gyrus, precuneus, and inferior frontal gyrus) were used in these analyses which were shown in a metaanalysis to be related to written word production on four indicators of white matter integrity and fMRI functional connectivity for four tasks (self-guided mind wandering during resting state, writing letter that follows a visually displayed letter in alphabet, writing missing letter to create a correctly spelled real word, and planning for composing after scanning on topic specified by researcher). For those DTI indicators on which the dysgraphic group or dyslexic group differed from the control group (fractional anisotropy, relative anisotropy, axial diffusivity but not radial diffusivity), correlations were computed between the DTI parameter and fMRI functional connectivity for the two writing tasks (alphabet and spelling) by seed points. Analyses, controlled for multiple comparisons, showed that (a) the control group exhibited more white matter integrity than either the dysgraphic or dyslexic group; (b) the dysgraphic and dyslexic groups showed more functional connectivity than the control group but differed in patterns of functional connectivity for task and seed point; and (c) the dysgraphic and dyslexic groups showed different patterns of significant DTI–fMRI connectivity correlations for specific seed points and written language tasks. Thus, dysgraphia and dyslexia differ in white matter integrity, fMRI functional connectivity, and white matter–gray matter

  15. Contrasting brain patterns of writing-related DTI parameters, fMRI connectivity, and DTI–fMRI connectivity correlations in children with and without dysgraphia or dyslexia

    Directory of Open Access Journals (Sweden)

    T.L. Richards

    2015-01-01

    Full Text Available Based on comprehensive testing and educational history, children in grades 4–9 (on average 12 years were diagnosed with dysgraphia (persisting handwriting impairment or dyslexia (persisting word spelling/reading impairment or as typical writers and readers (controls. The dysgraphia group (n = 14 and dyslexia group (n = 17 were each compared to the control group (n = 9 and to each other in separate analyses. Four brain region seed points (left occipital temporal gyrus, supramarginal gyrus, precuneus, and inferior frontal gyrus were used in these analyses which were shown in a metaanalysis to be related to written word production on four indicators of white matter integrity and fMRI functional connectivity for four tasks (self-guided mind wandering during resting state, writing letter that follows a visually displayed letter in alphabet, writing missing letter to create a correctly spelled real word, and planning for composing after scanning on topic specified by researcher. For those DTI indicators on which the dysgraphic group or dyslexic group differed from the control group (fractional anisotropy, relative anisotropy, axial diffusivity but not radial diffusivity, correlations were computed between the DTI parameter and fMRI functional connectivity for the two writing tasks (alphabet and spelling by seed points. Analyses, controlled for multiple comparisons, showed that (a the control group exhibited more white matter integrity than either the dysgraphic or dyslexic group; (b the dysgraphic and dyslexic groups showed more functional connectivity than the control group but differed in patterns of functional connectivity for task and seed point; and (c the dysgraphic and dyslexic groups showed different patterns of significant DTI–fMRI connectivity correlations for specific seed points and written language tasks. Thus, dysgraphia and dyslexia differ in white matter integrity, fMRI functional connectivity, and white matter–gray matter

  16. A DTI-based model for TMS using the independent impedance method with frequency-dependent tissue parameters

    Science.gov (United States)

    De Geeter, N.; Crevecoeur, G.; Dupré, L.; Van Hecke, W.; Leemans, A.

    2012-04-01

    Accurate simulations on detailed realistic head models are necessary to gain a better understanding of the response to transcranial magnetic stimulation (TMS). Hitherto, head models with simplified geometries and constant isotropic material properties are often used, whereas some biological tissues have anisotropic characteristics which vary naturally with frequency. Moreover, most computational methods do not take the tissue permittivity into account. Therefore, we calculate the electromagnetic behaviour due to TMS in a head model with realistic geometry and where realistic dispersive anisotropic tissue properties are incorporated, based on T1-weighted and diffusion-weighted magnetic resonance images. This paper studies the impact of tissue anisotropy, permittivity and frequency dependence, using the anisotropic independent impedance method. The results show that anisotropy yields differences up to 32% and 19% of the maximum induced currents and electric field, respectively. Neglecting the permittivity values leads to a decrease of about 72% and 24% of the maximum currents and field, respectively. Implementing the dispersive effects of biological tissues results in a difference of 6% of the maximum currents. The cerebral voxels show limited sensitivity of the induced electric field to changes in conductivity and permittivity, whereas the field varies approximately linearly with frequency. These findings illustrate the importance of including each of the above parameters in the model and confirm the need for accuracy in the applied patient-specific method, which can be used in computer-assisted TMS.

  17. Optimisation of process parameters in friction stir welding based on residual stress analysis: a feasibility study

    DEFF Research Database (Denmark)

    Tutum, Cem Celal; Hattel, Jesper Henri

    2010-01-01

    The present paper considers the optimisation of process parameters in friction stir welding (FSW). More specifically, the choices of rotational speed and traverse welding speed have been investigated using genetic algorithms. The welding process is simulated in a transient, two......-dimensional sequentially coupled thermomechanical model in ANSYS. This model is then used in an optimisation case where the two objectives are the minimisation of the peak residual stresses and the maximisation of the welding speed. The results indicate that the objectives for the considered case are conflicting......, and this is presented as a Pareto optimal front. Moreover, a higher welding speed for a fixed rotational speed results, in general, in slightly higher stress levels in the tension zone, whereas a higher rotational speed for a fixed welding speed yields somewhat lower peak residual stress, however, a wider tension zone...

  18. Optimisation of NMR dynamic models II. A new methodology for the dual optimisation of the model-free parameters and the Brownian rotational diffusion tensor

    International Nuclear Information System (INIS)

    D'Auvergne, Edward J.; Gooley, Paul R.

    2008-01-01

    Finding the dynamics of an entire macromolecule is a complex problem as the model-free parameter values are intricately linked to the Brownian rotational diffusion of the molecule, mathematically through the autocorrelation function of the motion and statistically through model selection. The solution to this problem was formulated using set theory as an element of the universal set U-the union of all model-free spaces (d'Auvergne EJ and Gooley PR (2007) Mol BioSyst 3(7), 483-494). The current procedure commonly used to find the universal solution is to initially estimate the diffusion tensor parameters, to optimise the model-free parameters of numerous models, and then to choose the best model via model selection. The global model is then optimised and the procedure repeated until convergence. In this paper a new methodology is presented which takes a different approach to this diffusion seeded model-free paradigm. Rather than starting with the diffusion tensor this iterative protocol begins by optimising the model-free parameters in the absence of any global model parameters, selecting between all the model-free models, and finally optimising the diffusion tensor. The new model-free optimisation protocol will be validated using synthetic data from Schurr JM et al. (1994) J Magn Reson B 105(3), 211-224 and the relaxation data of the bacteriorhodopsin (1-36)BR fragment from Orekhov VY (1999) J Biomol NMR 14(4), 345-356. To demonstrate the importance of this new procedure the NMR relaxation data of the Olfactory Marker Protein (OMP) of Gitti R et al. (2005) Biochem 44(28), 9673-9679 is reanalysed. The result is that the dynamics for certain secondary structural elements is very different from those originally reported

  19. New techniques for improved performance in surface blasting operation and optimisation of blast design parameters

    Energy Technology Data Exchange (ETDEWEB)

    Roy, P.P. [Central Mining Research Institute, Dhanbad (India). Blasting Dept.

    1999-02-01

    Experimental blasts were conducted for optimisation of blasting parameters using separate technologies involving non-electric initiation systems, air decking accessories in conjunction with different explosive products like emulsion (cartridge and site-mixed), slurries (cartridge and site-mixed) and ANFO. The cost associated with each such technology was then compared with the conventional methods of drilling and blasting operations. The results of cost analyses are given. Theoretical and practical aspects of such technologies and their best possible usage in order to establish the desired fragmentation, muck profile, wall control and ultimately the accepted level of costs are mentioned in subsequent sections. 16 refs., 17 figs., 8 plates, 11 tabs.

  20. Exploring the triplet parameters space to optimise the final focus of the FCC-hh

    CERN Document Server

    AUTHOR|(CDS)2141109; Abelleira, Jose; Seryi, Andrei; Cruz Alaniz, Emilia

    2017-01-01

    One of the main challenges when designing final focus systems of particle accelerators is maximising the beam stay clear in the strong quadrupole magnets of the inner triplet. Moreover it is desirable to keep the quadrupoles in the triplet as short as possible for space and costs reasons but also to reduce chromaticity and simplify corrections schemes. An algorithm that explores the triplet parameter space to optimise both these aspects was written. It uses thin lenses as a first approximation and MADX for more precise calculations. In cooperation with radiation studies, this algorithm was then applied to design an alternative triplet for the final focus of the Future Circular Collider (FCC-hh).

  1. Optimisation of parameters for co-precipitation of uranium and plutonium - results of simulation studies

    International Nuclear Information System (INIS)

    Pandey, N.K.; Velvandan, P.V.; Murugesan, S.; Ahmed, M.K.; Koganti, S.B.

    1999-01-01

    Preparation of plutonium oxide from plutonium nitrate solution generally proceeds via oxalate precipitation route. In a nuclear fuel reprocessing scheme this step succeeds the partitioning step (separation of uranium and plutonium). Results of present studies confirm that it is possible to avoid partitioning step and recover plutonium and uranium as co-precipitated product. This also helps in minimising the risk of proliferation of fissile material. In this procedure, the solubility of uranium oxalate in nitric acid is effectively used. Co-precipitation parameters are optimised with simulated solutions of uranium nitrate and thorium nitrate (in place of plutonium). On the basis of obtained results a reconversion flow-sheet is designed and reported here. (author)

  2. Plasma jet source parameter optimisation and experiments on injection into Globus-M spherical tokamak

    International Nuclear Information System (INIS)

    Gusev, V.K.; Petrov, Yu.V.; Sakharov, N.V.; Semenov, A.A.; Voronin, A.V.

    2005-01-01

    Results of theoretical and experimental research on the plasma sources and injection of plasma and gas jet produced by the modified source into tokamak Globus-M are presented. An experimental test stand was developed for investigation of intense plasma jet generation. Optimisation of pulsed coaxial accelerator parameters by means of analytical calculations is performed with the aim of achieving the highest flow velocity at limited coaxial electrode length and discharge current. The optimal parameters of power supply to generate a plasma jet with minimal impurity contamination and maximum flow velocity were determined. A comparison of experimental and calculation results is made. Plasma jet parameters are measured, such as: impurity species content, pressure distribution across the jet, flow velocity, plasma density, etc. Experiments on the interaction of a higher kinetic energy plasma jet with the magnetic field and plasma of the Globus-M tokamak were performed. Experimental results on plasma and gas jet injection into different Globus-M discharge phases are presented and discussed. Results are presented on the investigation of plasma jet injection as the source for discharge breakdown, plasma current startup and initial density rise. (author)

  3. The influence of the dwell time deviation constraint (DTDC) parameter on dosimetry with IPSA optimisation for HDR prostate brachytherapy

    International Nuclear Information System (INIS)

    Smith, Ryan L.; Millar, Jeremy L.; Panettieri, Vanessa; Mason, Natasha; Lancaster, Craig; Francih, Rick D.

    2015-01-01

    To investigate how the dwell time deviation constraint (DTDC) parameter, applied to inverse planning by simulated annealing (IPSA) optimisation limits large dwell times from occurring in each catheter and to characterise the effect on the resulting dosimetry for prostate high dose rate (HDR) brachytherapy treatment plans. An unconstrained IPSA optimised treatment plan, using the Oncentra Brachytherapy treatment planning system (version 4.3, Nucletron an Elekta company, Elekta AB, Stockholm, Sweden), was generated for 20 consecutive HDR prostate brachytherapy patients, with the DTDC set to zero. Successive constrained optimisation plans were also created for each patient by increasing the DTDC parameter by 0.2, up to a maximum value of 1.0. We defined a “plan modulation index”, to characterise the change of dwell time modulation as the DTDC parameter was increased. We calculated the dose volume histogram indices for the PTV (D90, V100, V150, V200%) and urethra (D10%) to characterise the effect on the resulting dosimetry. The average PTV D90% decreases as the DTDC is applied, on average by only 1.5 %, for a DTDC = 0.4. The measures of high dose regions in the PTV, V150 and V200%, increase on average by less than 5 and 2 % respectively. The net effect of DTDC on the modulation of dwell times has been characterised by the introduction of the plan modulation index. DTDC applied during IPSA optimisation of HDR prostate brachytherapy plans reduce the occurrence of large isolated dwell times within individual catheters. The mechanism by which DTDC works has been described and its effect on the modulation of dwell times has been characterised. The authors recommend using a DTDC parameter no greater than 0.4 to obtain a plan with dwell time modulation comparable to a geometric optimised plan. This yielded on average a 1.5 % decrease in PTV coverage and an acceptable increase in V150%, without compromising the urethral dose.

  4. Optimisation of process parameters on thin shell part using response surface methodology (RSM) and genetic algorithm (GA)

    Science.gov (United States)

    Faiz, J. M.; Shayfull, Z.; Nasir, S. M.; Fathullah, M.; Hazwan, M. H. M.

    2017-09-01

    This study conducts the simulation on optimisation of injection moulding process parameters using Autodesk Moldflow Insight (AMI) software. This study has applied some process parameters which are melt temperature, mould temperature, packing pressure, and cooling time in order to analyse the warpage value of the part. Besides, a part has been selected to be studied which made of Polypropylene (PP). The combination of the process parameters is analysed using Analysis of Variance (ANOVA) and the optimised value is obtained using Response Surface Methodology (RSM). The RSM as well as Genetic Algorithm are applied in Design Expert software in order to minimise the warpage value. The outcome of this study shows that the warpage value improved by using RSM and GA.

  5. MRI to X-ray mammography intensity-based registration with simultaneous optimisation of pose and biomechanical transformation parameters.

    Science.gov (United States)

    Mertzanidou, Thomy; Hipwell, John; Johnsen, Stian; Han, Lianghao; Eiben, Bjoern; Taylor, Zeike; Ourselin, Sebastien; Huisman, Henkjan; Mann, Ritse; Bick, Ulrich; Karssemeijer, Nico; Hawkes, David

    2014-05-01

    Determining corresponding regions between an MRI and an X-ray mammogram is a clinically useful task that is challenging for radiologists due to the large deformation that the breast undergoes between the two image acquisitions. In this work we propose an intensity-based image registration framework, where the biomechanical transformation model parameters and the rigid-body transformation parameters are optimised simultaneously. Patient-specific biomechanical modelling of the breast derived from diagnostic, prone MRI has been previously used for this task. However, the high computational time associated with breast compression simulation using commercial packages, did not allow the optimisation of both pose and FEM parameters in the same framework. We use a fast explicit Finite Element (FE) solver that runs on a graphics card, enabling the FEM-based transformation model to be fully integrated into the optimisation scheme. The transformation model has seven degrees of freedom, which include parameters for both the initial rigid-body pose of the breast prior to mammographic compression, and those of the biomechanical model. The framework was tested on ten clinical cases and the results were compared against an affine transformation model, previously proposed for the same task. The mean registration error was 11.6±3.8mm for the CC and 11±5.4mm for the MLO view registrations, indicating that this could be a useful clinical tool. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

  6. Optimisation of laser welding parameters for welding of P92 material using Taguchi based grey relational analysis

    Directory of Open Access Journals (Sweden)

    Shanmugarajan B.

    2016-08-01

    Full Text Available Creep strength enhanced ferritic (CSEF steels are used in advanced power plant systems for high temperature applications. P92 (Cr–W–Mo–V steel, classified under CSEF steels, is a candidate material for piping, tubing, etc., in ultra-super critical and advanced ultra-super critical boiler applications. In the present work, laser welding process has been optimised for P92 material by using Taguchi based grey relational analysis (GRA. Bead on plate (BOP trials were carried out using a 3.5 kW diffusion cooled slab CO2 laser by varying laser power, welding speed and focal position. The optimum parameters have been derived by considering the responses such as depth of penetration, weld width and heat affected zone (HAZ width. Analysis of variance (ANOVA has been used to analyse the effect of different parameters on the responses. Based on ANOVA, laser power of 3 kW, welding speed of 1 m/min and focal plane at −4 mm have evolved as optimised set of parameters. The responses of the optimised parameters obtained using the GRA have been verified experimentally and found to closely correlate with the predicted value.

  7. Review article – Optimisation of exposure parameters for spinal curvature measurements in paediatric radiography

    NARCIS (Netherlands)

    de Haan, Seraphine; Reis, Cláudia; Ndlovu, Junior; Serrenho, Catarina; Akhtar, Ifrah; Garcia, José Antonio; Linde, Daniël; Thorskog, Martine; Franco, Loris; Hogg, Peter

    2015-01-01

    This review aims to identify strategies to optimise radiography practice using digital technologies, for full spine studies on paediatrics focusing particularly on methods used to diagnose and measure severity of spinal curvatures. The literature search was performed on different databases (PubMed,

  8. Investigation into the optimal use of automatic optimisation of parameters (AOP) for mammography

    International Nuclear Information System (INIS)

    Herley, J.; Tan, W.

    2004-01-01

    Full text: Automatic Optimisation of Parameters (AOP) is an AEC function offered on GE Medical Systems mammography units. It optimizes x-ray exposure to give optimal image quality by automatically selecting Wp, target/filter and mAs according to the thickness and density of the breast. The Medical Physics group of Biomedical Technology Services (BTS) has conducted an investigation into the optimal use of the AOP modes for the GE Senographe 800T and GE Senographe DMR mammography units located in several BreastScreen Queensland (BSQ) clinics. Variation of image quality and dose using the three AOP modes were studied. The planned outcome is to develop a recommendation for the optimal use of AOP modes based on various breast thickness and composition. Both GE Senographe 800T and GE Senographe DMR have 3 AOP mode selections: CNT (contrast), STD (standard) and Dose. Various thickness of perspex ranging from 2cm to 8cm was compressed for each mode to determine the selection of kVp, target/filter and mAs for each apparatus. Image quality was evaluated using a Tor[Mam] phantom for various thicknesses in each AOP mode. The scoring system implemented for image quality was that recommended by Leeds X-ray Imaging (Lxi) where a numerical scale from O to 3 is used to denote the level of visibility of details perceived in the phantom image. Results confirmed that mean glandular dose (MGD) increases with breast thickness. Increasing image contrast will increase dose to breast due to lower energy radiation spectrum used. The GE Senographe DMR has the advantage of utilising a Rhodium target thus giving a lower MGD than the GE Senographe 800T at thickness above 4cm. Film image quality decreases with increasing thickness of perspex. A breast thickness of 2cm yields similar image quality in all 3 AOP modes as the selected kVp value and target filter (Mo/Mo) was similar. There was no significant difference in image quality for the GE Senographe DMR apparatus between 2cm and 4cm for all

  9. Direction-controlled DTI interpolation

    NARCIS (Netherlands)

    Florack, L.M.J.; Dela Haije, T.C.J.; Fuster, A.; Hotz, I.; Schultz, T.

    2015-01-01

    Diffusion Tensor Imaging (DTI) is a popular model for representing diffusion weighted magnetic resonance images due to its simplicity and the fact that it strikes a good balance between signal fit and robustness. Nevertheless, problematic issues remain. One of these concerns the problem of

  10. Experimental design optimisation: theory and application to estimation of receptor model parameters using dynamic positron emission tomography

    International Nuclear Information System (INIS)

    Delforge, J.; Syrota, A.; Mazoyer, B.M.

    1989-01-01

    General framework and various criteria for experimental design optimisation are presented. The methodology is applied to estimation of receptor-ligand reaction model parameters with dynamic positron emission tomography data. The possibility of improving parameter estimation using a new experimental design combining an injection of the β + -labelled ligand and an injection of the cold ligand is investigated. Numerical simulations predict remarkable improvement in the accuracy of parameter estimates with this new experimental design and particularly the possibility of separate estimations of the association constant (k +1 ) and of receptor density (B' max ) in a single experiment. Simulation predictions are validated using experimental PET data in which parameter uncertainties are reduced by factors ranging from 17 to 1000. (author)

  11. A method for the calculation of collision strengths for complex atomic structures based on Slater parameter optimisation

    International Nuclear Information System (INIS)

    Fawcett, B.C.; Mason, H.E.

    1989-02-01

    This report presents details of a new method to enable the computation of collision strengths for complex ions which is adapted from long established optimisation techniques previously applied to the calculation of atomic structures and oscillator strengths. The procedure involves the adjustment of Slater parameters so that they determine improved energy levels and eigenvectors. They provide a basis for collision strength calculations in ions where ab initio computations break down or result in reducible errors. This application is demonstrated through modifications of the DISTORTED WAVE collision code and SUPERSTRUCTURE atomic-structure code which interface via a transformation code JAJOM which processes their output. (author)

  12. Simulation optimisation

    International Nuclear Information System (INIS)

    Anon

    2010-01-01

    Over the past decade there has been a significant advance in flotation circuit optimisation through performance benchmarking using metallurgical modelling and steady-state computer simulation. This benchmarking includes traditional measures, such as grade and recovery, as well as new flotation measures, such as ore floatability, bubble surface area flux and froth recovery. To further this optimisation, Outotec has released its HSC Chemistry software with simulation modules. The flotation model developed by the AMIRA P9 Project, of which Outotec is a sponsor, is regarded by industry as the most suitable flotation model to use for circuit optimisation. This model incorporates ore floatability with flotation cell pulp and froth parameters, residence time, entrainment and water recovery. Outotec's HSC Sim enables you to simulate mineral processes in different levels, from comminution circuits with sizes and no composition, through to flotation processes with minerals by size by floatability components, to full processes with true particles with MLA data.

  13. Optimisation of shock absorber process parameters using failure mode and effect analysis and genetic algorithm

    Science.gov (United States)

    Mariajayaprakash, Arokiasamy; Senthilvelan, Thiyagarajan; Vivekananthan, Krishnapillai Ponnambal

    2013-07-01

    The various process parameters affecting the quality characteristics of the shock absorber during the process were identified using the Ishikawa diagram and by failure mode and effect analysis. The identified process parameters are welding process parameters (squeeze, heat control, wheel speed, and air pressure), damper sealing process parameters (load, hydraulic pressure, air pressure, and fixture height), washing process parameters (total alkalinity, temperature, pH value of rinsing water, and timing), and painting process parameters (flowability, coating thickness, pointage, and temperature). In this paper, the process parameters, namely, painting and washing process parameters, are optimized by Taguchi method. Though the defects are reasonably minimized by Taguchi method, in order to achieve zero defects during the processes, genetic algorithm technique is applied on the optimized parameters obtained by Taguchi method.

  14. Optimisation Of Process Parameters In High Energy Mixing As A Method Of Cohesive Powder Flowability Improvement

    Directory of Open Access Journals (Sweden)

    Leś Karolina

    2015-12-01

    Full Text Available Flowability of fine, highly cohesive calcium carbonate powder was improved using high energy mixing (dry coating method consisting in coating of CaCO3 particles with a small amount of Aerosil nanoparticles in a planetary ball mill. As measures of flowability the angle of repose and compressibility index were used. As process variables the mixing speed, mixing time, and the amount of Aerosil and amount of isopropanol were chosen. To obtain optimal values of the process variables, a Response Surface Methodology (RSM based on Central Composite Rotatable Design (CCRD was applied. To match the RSM requirements it was necessary to perform a total of 31 experimental tests needed to complete mathematical model equations. The equations that are second-order response functions representing the angle of repose and compressibility index were expressed as functions of all the process variables. Predicted values of the responses were found to be in a good agreement with experimental values. The models were presented as 3-D response surface plots from which the optimal values of the process variables could be correctly assigned. The proposed, mechanochemical method of powder treatment coupled with response surface methodology is a new, effective approach to flowability of cohesive powder improvement and powder processing optimisation.

  15. Simultaneous feature selection and parameter optimisation using an artificial ant colony: case study of melting point prediction

    Directory of Open Access Journals (Sweden)

    Nigsch Florian

    2008-10-01

    Full Text Available Abstract Background We present a novel feature selection algorithm, Winnowing Artificial Ant Colony (WAAC, that performs simultaneous feature selection and model parameter optimisation for the development of predictive quantitative structure-property relationship (QSPR models. The WAAC algorithm is an extension of the modified ant colony algorithm of Shen et al. (J Chem Inf Model 2005, 45: 1024–1029. We test the ability of the algorithm to develop a predictive partial least squares model for the Karthikeyan dataset (J Chem Inf Model 2005, 45: 581–590 of melting point values. We also test its ability to perform feature selection on a support vector machine model for the same dataset. Results Starting from an initial set of 203 descriptors, the WAAC algorithm selected a PLS model with 68 descriptors which has an RMSE on an external test set of 46.6°C and R2 of 0.51. The number of components chosen for the model was 49, which was close to optimal for this feature selection. The selected SVM model has 28 descriptors (cost of 5, ε of 0.21 and an RMSE of 45.1°C and R2 of 0.54. This model outperforms a kNN model (RMSE of 48.3°C, R2 of 0.47 for the same data and has similar performance to a Random Forest model (RMSE of 44.5°C, R2 of 0.55. However it is much less prone to bias at the extremes of the range of melting points as shown by the slope of the line through the residuals: -0.43 for WAAC/SVM, -0.53 for Random Forest. Conclusion With a careful choice of objective function, the WAAC algorithm can be used to optimise machine learning and regression models that suffer from overfitting. Where model parameters also need to be tuned, as is the case with support vector machine and partial least squares models, it can optimise these simultaneously. The moving probabilities used by the algorithm are easily interpreted in terms of the best and current models of the ants, and the winnowing procedure promotes the removal of irrelevant descriptors.

  16. Simultaneous feature selection and parameter optimisation using an artificial ant colony: case study of melting point prediction.

    Science.gov (United States)

    O'Boyle, Noel M; Palmer, David S; Nigsch, Florian; Mitchell, John Bo

    2008-10-29

    We present a novel feature selection algorithm, Winnowing Artificial Ant Colony (WAAC), that performs simultaneous feature selection and model parameter optimisation for the development of predictive quantitative structure-property relationship (QSPR) models. The WAAC algorithm is an extension of the modified ant colony algorithm of Shen et al. (J Chem Inf Model 2005, 45: 1024-1029). We test the ability of the algorithm to develop a predictive partial least squares model for the Karthikeyan dataset (J Chem Inf Model 2005, 45: 581-590) of melting point values. We also test its ability to perform feature selection on a support vector machine model for the same dataset. Starting from an initial set of 203 descriptors, the WAAC algorithm selected a PLS model with 68 descriptors which has an RMSE on an external test set of 46.6 degrees C and R2 of 0.51. The number of components chosen for the model was 49, which was close to optimal for this feature selection. The selected SVM model has 28 descriptors (cost of 5, epsilon of 0.21) and an RMSE of 45.1 degrees C and R2 of 0.54. This model outperforms a kNN model (RMSE of 48.3 degrees C, R2 of 0.47) for the same data and has similar performance to a Random Forest model (RMSE of 44.5 degrees C, R2 of 0.55). However it is much less prone to bias at the extremes of the range of melting points as shown by the slope of the line through the residuals: -0.43 for WAAC/SVM, -0.53 for Random Forest. With a careful choice of objective function, the WAAC algorithm can be used to optimise machine learning and regression models that suffer from overfitting. Where model parameters also need to be tuned, as is the case with support vector machine and partial least squares models, it can optimise these simultaneously. The moving probabilities used by the algorithm are easily interpreted in terms of the best and current models of the ants, and the winnowing procedure promotes the removal of irrelevant descriptors.

  17. Brute force meets Bruno force in parameter optimisation: introduction of novel constraints for parameter accuracy improvement by symbolic computation.

    Science.gov (United States)

    Nakatsui, M; Horimoto, K; Lemaire, F; Ürgüplü, A; Sedoglavic, A; Boulier, F

    2011-09-01

    Recent remarkable advances in computer performance have enabled us to estimate parameter values by the huge power of numerical computation, the so-called 'Brute force', resulting in the high-speed simultaneous estimation of a large number of parameter values. However, these advancements have not been fully utilised to improve the accuracy of parameter estimation. Here the authors review a novel method for parameter estimation using symbolic computation power, 'Bruno force', named after Bruno Buchberger, who found the Gröbner base. In the method, the objective functions combining the symbolic computation techniques are formulated. First, the authors utilise a symbolic computation technique, differential elimination, which symbolically reduces an equivalent system of differential equations to a system in a given model. Second, since its equivalent system is frequently composed of large equations, the system is further simplified by another symbolic computation. The performance of the authors' method for parameter accuracy improvement is illustrated by two representative models in biology, a simple cascade model and a negative feedback model in comparison with the previous numerical methods. Finally, the limits and extensions of the authors' method are discussed, in terms of the possible power of 'Bruno force' for the development of a new horizon in parameter estimation.

  18. Illustrative uncertainty visualization of DTI fiber pathways

    NARCIS (Netherlands)

    Brecheisen, R.; Platel, B.; Haar Romeny, B.M. Ter; Vilanova, A.

    2013-01-01

    Diffusion Tensor Imaging (DTI) and fiber tracking provide unique insight into the 3D structure of fibrous tissues in the brain. However, the output of fiber tracking contains a significant amount of uncertainty accumulated in the various steps of the processing pipeline. Existing DTI visualization

  19. Optimised polarimeter configurations for measuring the Stokes parameters of the Cosmic Microwave Background Radiation

    OpenAIRE

    Couchot, F.; Delabrouille, J.; Kaplan, J.; Revenu, B.

    1998-01-01

    We present configurations of polarimeters which measure the three linear Stokes parameters of the Cosmic Microwave Background Radiation with a nearly diagonal error matrix, independent of the global orientation of the polarimeters in the focal plane. These configurations also provide the smallest possible error box volume.

  20. Optimisation Of Cutting Parameters Of Composite Material Laser Cutting Process By Taguchi Method

    Science.gov (United States)

    Lokesh, S.; Niresh, J.; Neelakrishnan, S.; Rahul, S. P. Deepak

    2018-03-01

    The aim of this work is to develop a laser cutting process model that can predict the relationship between the process input parameters and resultant surface roughness, kerf width characteristics. The research conduct is based on the Design of Experiment (DOE) analysis. Response Surface Methodology (RSM) is used in this work. It is one of the most practical and most effective techniques to develop a process model. Even though RSM has been used for the optimization of the laser process, this research investigates laser cutting of materials like Composite wood (veneer)to be best circumstances of laser cutting using RSM process. The input parameters evaluated are focal length, power supply and cutting speed, the output responses being kerf width, surface roughness, temperature. To efficiently optimize and customize the kerf width and surface roughness characteristics, a machine laser cutting process model using Taguchi L9 orthogonal methodology was proposed.

  1. The using of model calculations for the optimisation of the virtual impactor parameters

    International Nuclear Information System (INIS)

    Kravchuk, T.A.; Lyubinskij, N.N.; Melenevskij, A.Eh.; Shcherbin, V.N.

    2000-01-01

    Some characteristics of virtual impactors have been determined by numerical solution of Navier-Stoces equations and the equations of motion of the particles. The effect of the nozzle Reynolds number, the fractioning of flows passing through the impactor, collection probe diameter, nozzle throat length, nozzle - to -collection probe distance and probe entrance form on heavy and light particle collection efficiencies has been studied. It was found that some particles would impact on the inner surface of the collection probe. The results show that the most parameters with the exception of the flow fractioning have little effect on the heavy particle collection efficiency. And vice versa the effect on collection probe losses was significant for the most of these parameters

  2. Evaluation of skeletal muscle DTI in patients with duchenne muscular dystrophy.

    Science.gov (United States)

    Hooijmans, M T; Damon, B M; Froeling, M; Versluis, M J; Burakiewicz, J; Verschuuren, J J G M; Niks, E H; Webb, A G; Kan, H E

    2015-11-01

    Diffusion tensor imaging (DTI) is a popular method to assess differences in fiber organization in diseased and healthy muscle tissue. Previous work has shown that muscle DTI measurements depend on signal-to-noise ratio (SNR), %fat, and tissue T2. The goal of this study was to evaluate the potential biasing effects of these factors on skeletal muscle DTI data in patients with Duchenne Muscular Dystrophy (DMD). MR images were obtained of the right lower leg of 21 DMD patients and 12 healthy controls on a Philips 3T system. DTI measurements were combined with quantitative in-vivo measures of mean water T2, %fat and SNR to evaluate their effect on DTI parameter estimation. All outcome measures were determined within ROIs drawn for six lower leg muscles. Between group analysis, using all ROIs, revealed a significantly elevated FA in the GCL, SOL and PER muscles (pDTI parameter estimation. These findings suggest that measuring mean water T2, %fat and SNR is essential to ascribe changes in DTI measures to intrinsic diffusion changes or to confounding influences. Copyright © 2015 John Wiley & Sons, Ltd.

  3. Parameter optimisation for a better representation of drought by LSMs: inverse modelling vs. sequential data assimilation

    Science.gov (United States)

    Dewaele, Hélène; Munier, Simon; Albergel, Clément; Planque, Carole; Laanaia, Nabil; Carrer, Dominique; Calvet, Jean-Christophe

    2017-09-01

    Soil maximum available water content (MaxAWC) is a key parameter in land surface models (LSMs). However, being difficult to measure, this parameter is usually uncertain. This study assesses the feasibility of using a 15-year (1999-2013) time series of satellite-derived low-resolution observations of leaf area index (LAI) to estimate MaxAWC for rainfed croplands over France. LAI interannual variability is simulated using the CO2-responsive version of the Interactions between Soil, Biosphere and Atmosphere (ISBA) LSM for various values of MaxAWC. Optimal value is then selected by using (1) a simple inverse modelling technique, comparing simulated and observed LAI and (2) a more complex method consisting in integrating observed LAI in ISBA through a land data assimilation system (LDAS) and minimising LAI analysis increments. The evaluation of the MaxAWC estimates from both methods is done using simulated annual maximum above-ground biomass (Bag) and straw cereal grain yield (GY) values from the Agreste French agricultural statistics portal, for 45 administrative units presenting a high proportion of straw cereals. Significant correlations (p value Bag and GY are found for up to 36 and 53 % of the administrative units for the inverse modelling and LDAS tuning methods, respectively. It is found that the LDAS tuning experiment gives more realistic values of MaxAWC and maximum Bag than the inverse modelling experiment. Using undisaggregated LAI observations leads to an underestimation of MaxAWC and maximum Bag in both experiments. Median annual maximum values of disaggregated LAI observations are found to correlate very well with MaxAWC.

  4. Geotechnical studies at Jaduguda uranium mine for optimisation of stopping and support parameters in molybdenite shear zone

    International Nuclear Information System (INIS)

    Ghosh, A.K.; Sinha, A.; Prasad, L.; Prasad, M.; Raju, N.M.

    1991-01-01

    In recent years, a few geotechnical studies have been conducted by the Central Mining Research Station, Dhanbad, at Jaduguda mine to improve ground control system and to optimise stopping parameters in the wide orebody zone at deeper levels and thus to add to productivity and recovery of these mines ensuring adequate safety. The replacement of mechanical point-anchored rock-bolts by full column cement grouted bolts, installed as per the designed pattern, has improved the ground condition, decreased the consumption of timber supports by around 70%, curtailed the support installation time and reduced the support cost to a remarkable extent even at the most problematic sites of Jaduguda mine. The analysis of stress development observations in the slope pillars of this mine reveals that the size of the slope pillars may be reduced by 20% in width which means an extra recovery of about 75 to 100 tonnes of ore per pillar per slice. In this paper, the authors have presented a brief account of their studies at this mine in the last four years. (author). 10 refs., 10 tabs., 9 figs

  5. Optimising Drug Solubilisation in Amorphous Polymer Dispersions: Rational Selection of Hot-melt Extrusion Processing Parameters.

    Science.gov (United States)

    Li, Shu; Tian, Yiwei; Jones, David S; Andrews, Gavin P

    2016-02-01

    The aim of this article was to construct a T-ϕ phase diagram for a model drug (FD) and amorphous polymer (Eudragit® EPO) and to use this information to understand the impact of how temperature-composition coordinates influenced the final properties of the extrudate. Defining process boundaries and understanding drug solubility in polymeric carriers is of utmost importance and will help in the successful manufacture of new delivery platforms for BCS class II drugs. Physically mixed felodipine (FD)-Eudragit(®) EPO (EPO) binary mixtures with pre-determined weight fractions were analysed using DSC to measure the endset of melting and glass transition temperature. Extrudates of 10 wt% FD-EPO were processed using temperatures (110°C, 126°C, 140°C and 150°C) selected from the temperature-composition (T-ϕ) phase diagrams and processing screw speed of 20, 100 and 200rpm. Extrudates were characterised using powder X-ray diffraction (PXRD), optical, polarised light and Raman microscopy. To ensure formation of a binary amorphous drug dispersion (ADD) at a specific composition, HME processing temperatures should at least be equal to, or exceed, the corresponding temperature value on the liquid-solid curve in a F-H T-ϕ phase diagram. If extruded between the spinodal and liquid-solid curve, the lack of thermodynamic forces to attain complete drug amorphisation may be compensated for through the use of an increased screw speed. Constructing F-H T-ϕ phase diagrams are valuable not only in the understanding drug-polymer miscibility behaviour but also in rationalising the selection of important processing parameters for HME to ensure miscibility of drug and polymer.

  6. Optimal Optimisation in Chemometrics

    NARCIS (Netherlands)

    Hageman, J.A.

    2004-01-01

    The use of global optimisation methods is not straightforward, especially for the more difficult optimisation problems. Solutions have to be found for items such as the evaluation function, representation, step function and meta-parameters, before any useful results can be obtained. This thesis aims

  7. DTI measurements for Alzheimer’s classification

    Science.gov (United States)

    Maggipinto, Tommaso; Bellotti, Roberto; Amoroso, Nicola; Diacono, Domenico; Donvito, Giacinto; Lella, Eufemia; Monaco, Alfonso; Antonella Scelsi, Marzia; Tangaro, Sabina; Disease Neuroimaging Initiative, Alzheimer's.

    2017-03-01

    Diffusion tensor imaging (DTI) is a promising imaging technique that provides insight into white matter microstructure integrity and it has greatly helped identifying white matter regions affected by Alzheimer’s disease (AD) in its early stages. DTI can therefore be a valuable source of information when designing machine-learning strategies to discriminate between healthy control (HC) subjects, AD patients and subjects with mild cognitive impairment (MCI). Nonetheless, several studies have reported so far conflicting results, especially because of the adoption of biased feature selection strategies. In this paper we firstly analyzed DTI scans of 150 subjects from the Alzheimer’s disease neuroimaging initiative (ADNI) database. We measured a significant effect of the feature selection bias on the classification performance (p-value  informative content provided by DTI measurements for AD classification. Classification performances and biological insight, concerning brain regions related to the disease, provided by cross-validation analysis were both confirmed on the independent test.

  8. Diagnostic utility of DTI in prostate cancer

    Energy Technology Data Exchange (ETDEWEB)

    Guerses, Bengi, E-mail: bengur0@yahoo.com [Yeditepe University Medical Faculty, Department of Radiology, Istanbul (Turkey); Tasdelen, Neslihan [Yeditepe University Medical Faculty, Department of Radiology, Istanbul (Turkey); Yencilek, Faruk [Yeditepe University Medical Faculty, Department of Urology, Istanbul (Turkey); Kilickesmez, N. Ozguer [Yeditepe University Medical Faculty, Department of Radiology, Istanbul (Turkey); Alp, Turgut [Fatih Sultan Mehmet Training and Research Hospital, Division of Urology, Istanbul (Turkey); Firat, Zeynep [Yeditepe University Medical Faculty, Department of Radiology, Istanbul (Turkey); Albayrak, M. Selami [Kartal Training and Research Hospital, Division of Urology, Istanbul (Turkey); Ulug, Aziz M. [Yeditepe University Department of Biomedical Engineering, Istanbul (Turkey); The Feinstein Institute for Medical Research, Manhasset, New York (United States); Guermen, A. Nevzat [Yeditepe University Medical Faculty, Department of Radiology, Istanbul (Turkey)

    2011-08-15

    Purpose: The aim of this study was to compare the diffusion tensor parameters of prostate cancer, prostatitis and normal prostate tissue. Materials and Methods: A total of 25 patients with the suspicion of prostate cancer were included in the study. MRI was performed with 3 T system (Intera Achieva, Philips Medical Systems, The Netherlands). T2 TSE and DTI with ss-EPI were obtained in each subject. TRUS-guided prostate biopsy was performed after the MRI examination. Images were analyzed by two radiologists using a special software system. ROI's were drawn according to biopsy zones which are apex, midgland, base and central zone on each sides of the gland. FA and ADC values in areas of cancer, chronic prostatitis and normal prostate tissue were compared using Student's t-test. Results: Histopathological analysis revealed carcinoma in 68, chronic prostatitis in 67 and was reported as normal in 65 zones. The mean FA of cancerous tissue was significantly higher (p < 0.01) than the FA of chronic prostatitis and normal gland. The mean ADC of cancerous tissue was found to be significantly lower (p < 0.01), compared with non-cancerous tissue. Conclusion: Decreased ADC and increased FA are compatible with the hypercellular nature of prostate tumors. These differences may increase the accuracy of MRI in the detection of carcinoma and to differentiate between cancer and prostatitis.

  9. Diagnostic utility of DTI in prostate cancer

    International Nuclear Information System (INIS)

    Guerses, Bengi; Tasdelen, Neslihan; Yencilek, Faruk; Kilickesmez, N. Ozguer; Alp, Turgut; Firat, Zeynep; Albayrak, M. Selami; Ulug, Aziz M.; Guermen, A. Nevzat

    2011-01-01

    Purpose: The aim of this study was to compare the diffusion tensor parameters of prostate cancer, prostatitis and normal prostate tissue. Materials and Methods: A total of 25 patients with the suspicion of prostate cancer were included in the study. MRI was performed with 3 T system (Intera Achieva, Philips Medical Systems, The Netherlands). T2 TSE and DTI with ss-EPI were obtained in each subject. TRUS-guided prostate biopsy was performed after the MRI examination. Images were analyzed by two radiologists using a special software system. ROI's were drawn according to biopsy zones which are apex, midgland, base and central zone on each sides of the gland. FA and ADC values in areas of cancer, chronic prostatitis and normal prostate tissue were compared using Student's t-test. Results: Histopathological analysis revealed carcinoma in 68, chronic prostatitis in 67 and was reported as normal in 65 zones. The mean FA of cancerous tissue was significantly higher (p < 0.01) than the FA of chronic prostatitis and normal gland. The mean ADC of cancerous tissue was found to be significantly lower (p < 0.01), compared with non-cancerous tissue. Conclusion: Decreased ADC and increased FA are compatible with the hypercellular nature of prostate tumors. These differences may increase the accuracy of MRI in the detection of carcinoma and to differentiate between cancer and prostatitis.

  10. Revised DTI Guidelines for Petroleum Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, D.; Philip, L.N.

    1997-07-01

    The DTI's guidelines on petroleum measurement have been extensively revised and enlarged. The new guidelines cover a much wider scope of measurement situations than before. Included in the new issue is guidance on allocation measurement, well testing, multiphase flow measurement, new technology acceptance procedures and operating procedures for different types of measurement systems. Significant changes have taken place in recent years both in the way the oil and gas industry conducts its business and in the fiscal regime operated by the UK government. New developments in flow measurement have progressed to such an extent that they have now been adopted by the industry or are close to being adopted as beneficial methods of the measurement of hydrocarbons in whatever form they present themselves for measurement. The rapid pace of development has left the standards-making bodies behind and in some cases there is insufficient quality data to enable the standards makers to produce guidance of the generic type appropriate for national or international standards. The case-by-case approach of the DTI in approving methods of measurement lends itself better to consideration of new technology where there may be no existing standards. These, amongst other considerations, make it appropriate for the DTI to extend the scope of its guidance into these new areas. The policy developments behind the changes in the new guidelines are not static and this new document has been produced in response to an evolutionary process which is still continuing but it is right to collate and make defining statements from time to time to put on record the current status of measurement requirements for the purpose of attaining DTI approval. (author)

  11. Biological effective dose evaluation in gynaecological brachytherapy: LDR and HDR treatments, dependence on radiobiological parameters, and treatment optimisation.

    Science.gov (United States)

    Bianchi, C; Botta, F; Conte, L; Vanoli, P; Cerizza, L

    2008-10-01

    This study was undertaken to compare the biological efficacy of different high-dose-rate (HDR) and low-dose-rate (LDR) treatments of gynaecological lesions, to identify the causes of possible nonuniformity and to optimise treatment through customised calculation. The study considered 110 patients treated between 2001 and 2006 with external beam radiation therapy and/or brachytherapy with either LDR (afterloader Selectron, (137)Cs) or HDR (afterloader microSelectron Classic, (192)Ir). The treatments were compared in terms of biologically effective dose (BED) to the tumour and to the rectum (linear-quadratic model) by using statistical tests for comparisons between independent samples. The difference between the two treatments was statistically significant in one case only. However, within each technique, we identified considerable nonuniformity in therapeutic efficacy due to differences in fractionation schemes and overall treatment time. To solve this problem, we created a Microsoft Excel spreadsheet allowing calculation of the optimal treatment for each patient: best efficacy (BED(tumour)) without exceeding toxicity threshold (BED(rectum)). The efficacy of a treatment may vary as a result of several factors. Customised radiobiological evaluation is a useful adjunct to clinical evaluation in planning equivalent treatments that satisfy all dosimetric constraints.

  12. Optimisation of the parameters of a pump chamber for solid-state lasers with diode pumping by the optical boiler method

    Energy Technology Data Exchange (ETDEWEB)

    Kiyko, V V; Kislov, V I; Ofitserov, E N; Suzdal' tsev, A G [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2015-06-30

    A pump chamber of the optical boiler type for solid-state lasers with transverse laser diode pumping is studied theoretically and experimentally. The pump chamber parameters are optimised using the geometrical optics approximation for the pump radiation. According to calculations, the integral absorption coefficient of the active element at a wavelength of 808 nm is 0.75 – 0.8 and the relative inhomogeneity of the pump radiation distribution over the active element volume is 17% – 19%. The developed pump chamber was used in a Nd:YAG laser. The maximum cw output power at a wavelength of 1064 nm was ∼480 W at the optical efficiency up to 19.6%, which agrees with theoretical estimates. (lasers)

  13. A Slater parameter optimisation interface for the CIV3 atomic structure code and its possible use with the R-matrix close coupling collision code

    International Nuclear Information System (INIS)

    Fawcett, B.C.; Hibbert, A.

    1989-11-01

    Details are here provided of amendments to the atomic structure code CIV3 which allow the optional adjustment of Slater parameters and average energies of configurations so that they result in improved energy levels and eigenvectors. It is also indicated how, in principle, the resultant improved eigenvectors can be utilised by the R-matrix collision code, thus providing an optimised target for close coupling collision strength calculations. An analogous computational method was recently reported for distorted wave collision strength calculations and applied to Fe XIII. The general method is suitable for the computation of collision strengths for complex ions and in some cases can then provide a basis for collision strength calculations in ions where ab initio computations break down or result in unnecessarily large errors. (author)

  14. Optimisation of the CT parameters with evaluation of MDCT double-scan images in the planning of the dental implant treatment

    International Nuclear Information System (INIS)

    Wojciechowski, W.; Urbanik, A.; Kownacki, P.; Kownacki, S.; Sowa, A.

    2009-01-01

    Background: The aim of the present study was optimisation of the examination parameters and evaluation of reliability of the MDCT double-scan images obtained with computer navigation for dental implant treatment. Material/Methods: With the use of a MDCT scanner SOMATOM Sensation (Siemens), CT-images of a phantom were performed: slice-collimation (10 A - 0.75 mm, 10 A - 1.5 mm), slice-thickness (0.75, 1, 2, 3, 5 mm), pitch (0.5, 1, 1.5). Additionally, the analysis on various filters from H20f to H60f was performed. For study used a phantom of the human cadaver head. Qualitative analysis was done using Nobel Guide (Nobel Biocare, Sweden), assessing possible artefacts on the images, and measurements of the bone structure on all filters in comparison with the real image. Results: The quality of the phantom images was assessed as optimal for the slices thickness 0.75 and 1 mm. The use of various values of the pitch did not have statistically significant difference on the image quality. Application of various filters did not alter the parameters of the bone structure, however the use of lower filters (H30f and H40f) had a beneficial effect on the quality of 3D reconstruction. The arrangement of the 'window' parameters in CT seemed to have a greater influence on the measurement and evaluation of the bone structure. Conclusions: Slice-collimation and slice-thickness are the most important parameters in selection of the optimal scan-protocol. It is recommended to use in the postprocessing, the mentioned above parameter succession with the application of various filters (H30f and H60f) at a stable arrangement of the 'window' in the CT examination. (authors)

  15. Researches regarding the reducing of burr size by optimising the cutting parameters on a CNC milling machine

    Directory of Open Access Journals (Sweden)

    Biriş Cristina

    2017-01-01

    Full Text Available This paper presents some experimental researches regarding burrs dimensions reduction that appear after the milling process together with an approach to reduce or eliminate the burrs resulted after this process. In order to reduce burrs dimensions, the milling process was executed with different cutting parameters and strategies then the results were evaluated.

  16. A preliminary study of DTI Fingerprinting on stroke analysis.

    Science.gov (United States)

    Ma, Heather T; Ye, Chenfei; Wu, Jun; Yang, Pengfei; Chen, Xuhui; Yang, Zhengyi; Ma, Jingbo

    2014-01-01

    DTI (Diffusion Tensor Imaging) is a well-known MRI (Magnetic Resonance Imaging) technique which provides useful structural information about human brain. However, the quantitative measurement to physiological variation of subtypes of ischemic stroke is not available. An automatically quantitative method for DTI analysis will enhance the DTI application in clinics. In this study, we proposed a DTI Fingerprinting technology to quantitatively analyze white matter tissue, which was applied in stroke classification. The TBSS (Tract Based Spatial Statistics) method was employed to generate mask automatically. To evaluate the clustering performance of the automatic method, lesion ROI (Region of Interest) is manually drawn on the DWI images as a reference. The results from the DTI Fingerprinting were compared with those obtained from the reference ROIs. It indicates that the DTI Fingerprinting could identify different states of ischemic stroke and has promising potential to provide a more comprehensive measure of the DTI data. Further development should be carried out to improve DTI Fingerprinting technology in clinics.

  17. Higher adsorption capacity of Spirulina platensis alga for Cr(VI) ions removal: parameter optimisation, equilibrium, kinetic and thermodynamic predictions.

    Science.gov (United States)

    Gunasundari, Elumalai; Senthil Kumar, Ponnusamy

    2017-04-01

    This study discusses about the biosorption of Cr(VI) ion from aqueous solution using ultrasonic assisted Spirulina platensis (UASP). The prepared UASP biosorbent was characterised by Fourier transform infrared spectroscopy, X-ray diffraction, Brunauer-Emmet-Teller, scanning electron spectroscopy and energy dispersive X-ray and thermogravimetric analyses. The optimum condition for the maximum removal of Cr(VI) ions for an initial concentration of 50 mg/l by UASP was measured as: adsorbent dose of 1 g/l, pH of 3.0, contact time of 30 min and temperature of 303 K. Adsorption isotherm, kinetics and thermodynamic parameters were calculated. Freundlich model provided the best results for the removal of Cr(VI) ions by UASP. The adsorption kinetics of Cr(VI) ions onto UASP showed that the pseudo-first-order model was well in line with the experimental data. In the thermodynamic study, the parameters like Gibb's free energy, enthalpy and entropy changes were evaluated. This result explains that the adsorption of Cr(VI) ions onto the UASP was exothermic and spontaneous in nature. Desorption of the biosorbent was done using different desorbing agents in which NaOH gave the best result. The prepared material showed higher affinity for the removal of Cr(VI) ions and this may be an alternative material to the existing commercial adsorbents.

  18. White Matter Changes in Bipolar Disorder, Alzheimer Disease, and Mild Cognitive Impairment: New Insights from DTI

    Directory of Open Access Journals (Sweden)

    Aikaterini Xekardaki

    2011-01-01

    Full Text Available Neuropathological and neuroimaging studies have reported significant changes in white matter in psychiatric and neurodegenerative diseases. Diffusion tensor imaging (DTI, a recently developed technique, enables the detection of microstructural changes in white matter. It is a noninvasive in vivo technique that assesses water molecules' diffusion in brain tissues. The most commonly used parameters are axial and radial diffusivity reflecting diffusion along and perpendicular to the axons, as well as mean diffusivity and fractional anisotropy representing global diffusion. Although the combination of these parameters provides valuable information about the integrity of brain circuits, their physiological meaning still remains controversial. After reviewing the basic principles of DTI, we report on recent contributions that used this technique to explore subtle structural changes in white matter occurring in elderly patients with bipolar disorder and Alzheimer disease.

  19. Role of DTI neuroimaging in diagnosis of vascular dementia

    International Nuclear Information System (INIS)

    Kozarova, G.; Georgieva- Penev, L.

    2013-01-01

    Full text: Introduction: Since its introduction more than two decades ago, Magnetic Resonance Imaging (MRI) has not only allowed for visualization of the macrostructure of the CNS, but also has been able to study dynamic processes which constitute the substrate of currently available MRI variants. Materials and methods: In this presentation, the potential role of MRI techniques, particularly DTI, for the study of the relationship between changes in the microstructural integrity of WM and cognitive impairment in the context of cerebrovascular disease and particularly the vascular dementia (VaD) are discussed. Results: While conventional Diffusion Weighted Imaging (DWI) permits a robust visualization of lesions just a few minutes after the onset of cerebral ischemia, Diffusion Tensor Imaging (DTI) measures the magnitude and direction of diffusion, leading to the characterization of cerebral white matter (WM) microstructural integrity of white matter fibers using quantitative fractionated anisotropy (DTI-FA) and tractography (DTI-TR). DTI-FA is an important technique in considering the large extension of white matter, and has been previously applied in clinical practice. DTI-TR can visualize the bundles interconnecting various regions whose interruption can cause a range of different disconnection syndromes. The method is not routinely used in clinical practice.In this presentation, the potential role of MRI techniques, particularly DTI, for the study of the relationship between changes in the microstructural integrity of WM and cognitive impairment in the context of cerebrovascular disease and particularly the vascular dementia (VaD) are discussed. Conclusion: Significant correlations between cognitive function and regional anisotropy values are an example of the potential efficacy of DTI for in vivo studies of brain connectivity in vascular neurodegenerative conditions

  20. Optimisation of technical specifications using probabilistic methods

    International Nuclear Information System (INIS)

    Ericsson, G.; Knochenhauer, M.; Hultqvist, G.

    1986-01-01

    During the last few years the development of methods for modifying and optimising nuclear power plant Technical Specifications (TS) for plant operations has received increased attention. Probalistic methods in general, and the plant and system models of probabilistic safety assessment (PSA) in particular, seem to provide the most forceful tools for optimisation. This paper first gives some general comments on optimisation, identifying important parameters and then gives a description of recent Swedish experiences from the use of nuclear power plant PSA models and results for TS optimisation

  1. Layout Optimisation of Wave Energy Converter Arrays

    DEFF Research Database (Denmark)

    Ruiz, Pau Mercadé; Nava, Vincenzo; Topper, Mathew B. R.

    2017-01-01

    This paper proposes an optimisation strategy for the layout design of wave energy converter (WEC) arrays. Optimal layouts are sought so as to maximise the absorbed power given a minimum q-factor, the minimum distance between WECs, and an area of deployment. To guarantee an efficient optimisation......, a four-parameter layout description is proposed. Three different optimisation algorithms are further compared in terms of performance and computational cost. These are the covariance matrix adaptation evolution strategy (CMA), a genetic algorithm (GA) and the glowworm swarm optimisation (GSO) algorithm...

  2. Optimisation of monochrome images

    International Nuclear Information System (INIS)

    Potter, R.

    1983-01-01

    Gamma cameras with modern imaging systems usually digitize the signals to allow storage and processing of the image in a computer. Although such computer systems are widely used for the extraction of quantitative uptake estimates and the analysis of time variant data, the vast majority of nuclear medicine images is still interpreted on the basis of an observer's visual assessment of a photographic hardcopy image. The optimisation of hardcopy devices is therefore vital and factors such as resolution, uniformity, noise grey scales and display matrices are discussed. Once optimum display parameters have been determined, routine procedures for quality control need to be established; suitable procedures are discussed. (U.K.)

  3. Particle swarm optimisation classical and quantum perspectives

    CERN Document Server

    Sun, Jun; Wu, Xiao-Jun

    2016-01-01

    IntroductionOptimisation Problems and Optimisation MethodsRandom Search TechniquesMetaheuristic MethodsSwarm IntelligenceParticle Swarm OptimisationOverviewMotivationsPSO Algorithm: Basic Concepts and the ProcedureParadigm: How to Use PSO to Solve Optimisation ProblemsSome Harder Examples Some Variants of Particle Swarm Optimisation Why Does the PSO Algorithm Need to Be Improved? Inertia and Constriction-Acceleration Techniques for PSOLocal Best ModelProbabilistic AlgorithmsOther Variants of PSO Quantum-Behaved Particle Swarm Optimisation OverviewMotivation: From Classical Dynamics to Quantum MechanicsQuantum Model: Fundamentals of QPSOQPSO AlgorithmSome Essential ApplicationsSome Variants of QPSOSummary Advanced Topics Behaviour Analysis of Individual ParticlesConvergence Analysis of the AlgorithmTime Complexity and Rate of ConvergenceParameter Selection and PerformanceSummaryIndustrial Applications Inverse Problems for Partial Differential EquationsInverse Problems for Non-Linear Dynamical SystemsOptimal De...

  4. Segmentation of DTI based on tensorial morphological gradient

    Science.gov (United States)

    Rittner, Leticia; de Alencar Lotufo, Roberto

    2009-02-01

    This paper presents a segmentation technique for diffusion tensor imaging (DTI). This technique is based on a tensorial morphological gradient (TMG), defined as the maximum dissimilarity over the neighborhood. Once this gradient is computed, the tensorial segmentation problem becomes an scalar one, which can be solved by conventional techniques, such as watershed transform and thresholding. Similarity functions, namely the dot product, the tensorial dot product, the J-divergence and the Frobenius norm, were compared, in order to understand their differences regarding the measurement of tensor dissimilarities. The study showed that the dot product and the tensorial dot product turned out to be inappropriate for computation of the TMG, while the Frobenius norm and the J-divergence were both capable of measuring tensor dissimilarities, despite the distortion of Frobenius norm, since it is not an affine invariant measure. In order to validate the TMG as a solution for DTI segmentation, its computation was performed using distinct similarity measures and structuring elements. TMG results were also compared to fractional anisotropy. Finally, synthetic and real DTI were used in the method validation. Experiments showed that the TMG enables the segmentation of DTI by watershed transform or by a simple choice of a threshold. The strength of the proposed segmentation method is its simplicity and robustness, consequences of TMG computation. It enables the use, not only of well-known algorithms and tools from the mathematical morphology, but also of any other segmentation method to segment DTI, since TMG computation transforms tensorial images in scalar ones.

  5. Optimising of design parameters of the TESLA vertex detector and search for events with isolated leptons and large missing transverse momentum with the ZEUS-experiment (HERA II)

    Energy Technology Data Exchange (ETDEWEB)

    Adler, V.

    2006-06-15

    In this thesis, a search for events with isolated leptons and large missing transverse momentum at HERA is presented. Data with an integrated luminosity of 40.76 pb{sup -1} of e{sup +}p-collisions collected with the ZEUS detector at a CMS energy of 318 GeV during the HERA II running period in the years 2003 and 2004 were used. Some extensions of the SM contain FCNC processes at tree level, which could lead to a significantly enhanced rate of singly produced t-quarks at HERA (e{sup {+-}}p {yields} e{sup {+-}}tX). The signature of interest originates from the decay t {yields} bW{sup +} with a subsequent leptonic decay of the W-boson (W{sup +} {yields} e{sup +}{nu}{sub e}, {mu}{sup +}{nu}{sub {mu}}, {tau}{sup +}{nu}{sub {tau}}). After the final selection, one event was found in data in the combined e- and {mu}-channels, where 1.27{+-}0.15 were expected from SM predictions. The selection efficiency in these channels was 13.4{sup +1.8}{sub -0.8}% for a t-quark mass of 175 GeV. In combination with independent searches in HERA I data in both, the leptonic and hadronic channel, limits on the FCNC couplings through photon and Z-boson exchange were derived. The NLO limit {kappa}{sub tu{gamma}}<0.160{sup +0.014}{sub -0.012} at 95% CL for a t-quark mass of 175 GeV is the most stringent so far. Together with the most stingent limit on v{sub tuz} of 0.37, an upper cross section limit of {sigma}{sub single} {sub t}<0.186{sup +0.029}{sub -0.012} pb was obtained.Also a limit on the cross section of single W-boson production of {sigma}{sub single} {sub W}<1.54{sup +0.67}{sub -0.41} pb was obtained at 95% CL. In this thesis, also a simulation study to optimise design parameters of a MAPS based vertex detector for a future ILC is presented. The study was based on the TESLA TDR. In order to evaluate the effect of different design options for the vertex detector on the physics performance of the whole detector, the reconstruction of the t-quark mass from the signal process e{sup +}e

  6. Optimising of design parameters of the TESLA vertex detector and search for events with isolated leptons and large missing transverse momentum with the ZEUS-experiment (HERA II)

    International Nuclear Information System (INIS)

    Adler, V.

    2006-06-01

    In this thesis, a search for events with isolated leptons and large missing transverse momentum at HERA is presented. Data with an integrated luminosity of 40.76 pb -1 of e + p-collisions collected with the ZEUS detector at a CMS energy of 318 GeV during the HERA II running period in the years 2003 and 2004 were used. Some extensions of the SM contain FCNC processes at tree level, which could lead to a significantly enhanced rate of singly produced t-quarks at HERA (e ± p → e ± tX). The signature of interest originates from the decay t → bW + with a subsequent leptonic decay of the W-boson (W + → e + ν e , μ + ν μ , τ + ν τ ). After the final selection, one event was found in data in the combined e- and μ-channels, where 1.27±0.15 were expected from SM predictions. The selection efficiency in these channels was 13.4 +1.8 -0.8 % for a t-quark mass of 175 GeV. In combination with independent searches in HERA I data in both, the leptonic and hadronic channel, limits on the FCNC couplings through photon and Z-boson exchange were derived. The NLO limit κ tuγ +0.014 -0.012 at 95% CL for a t-quark mass of 175 GeV is the most stringent so far. Together with the most stingent limit on v tuz of 0.37, an upper cross section limit of σ single t +0.029 -0.012 pb was obtained.Also a limit on the cross section of single W-boson production of σ single W +0.67 -0.41 pb was obtained at 95% CL. In this thesis, also a simulation study to optimise design parameters of a MAPS based vertex detector for a future ILC is presented. The study was based on the TESLA TDR. In order to evaluate the effect of different design options for the vertex detector on the physics performance of the whole detector, the reconstruction of the t-quark mass from the signal process e + e - →t anti t in the all-hadronic decay channel was used. The fast simulation program SGV was equipped with a neural-network based heavy-flavour tagging, where the b-tagging achieved a purity of 86% at an

  7. Methodological principles for optimising functional MRI experiments

    International Nuclear Information System (INIS)

    Wuestenberg, T.; Giesel, F.L.; Strasburger, H.

    2005-01-01

    Functional magnetic resonance imaging (fMRI) is one of the most common methods for localising neuronal activity in the brain. Even though the sensitivity of fMRI is comparatively low, the optimisation of certain experimental parameters allows obtaining reliable results. In this article, approaches for optimising the experimental design, imaging parameters and analytic strategies will be discussed. Clinical neuroscientists and interested physicians will receive practical rules of thumb for improving the efficiency of brain imaging experiments. (orig.) [de

  8. Evolutionary programming for neutron instrument optimisation

    Energy Technology Data Exchange (ETDEWEB)

    Bentley, Phillip M. [Hahn-Meitner Institut, Glienicker Strasse 100, D-14109 Berlin (Germany)]. E-mail: phillip.bentley@hmi.de; Pappas, Catherine [Hahn-Meitner Institut, Glienicker Strasse 100, D-14109 Berlin (Germany); Habicht, Klaus [Hahn-Meitner Institut, Glienicker Strasse 100, D-14109 Berlin (Germany); Lelievre-Berna, Eddy [Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9 (France)

    2006-11-15

    Virtual instruments based on Monte-Carlo techniques are now integral part of novel instrumentation development and the existing codes (McSTAS and Vitess) are extensively used to define and optimise novel instrumental concepts. Neutron spectrometers, however, involve a large number of parameters and their optimisation is often a complex and tedious procedure. Artificial intelligence algorithms are proving increasingly useful in such situations. Here, we present an automatic, reliable and scalable numerical optimisation concept based on the canonical genetic algorithm (GA). The algorithm was used to optimise the 3D magnetic field profile of the NSE spectrometer SPAN, at the HMI. We discuss the potential of the GA which combined with the existing Monte-Carlo codes (Vitess, McSTAS, etc.) leads to a very powerful tool for automated global optimisation of a general neutron scattering instrument, avoiding local optimum configurations.

  9. Evolutionary programming for neutron instrument optimisation

    International Nuclear Information System (INIS)

    Bentley, Phillip M.; Pappas, Catherine; Habicht, Klaus; Lelievre-Berna, Eddy

    2006-01-01

    Virtual instruments based on Monte-Carlo techniques are now integral part of novel instrumentation development and the existing codes (McSTAS and Vitess) are extensively used to define and optimise novel instrumental concepts. Neutron spectrometers, however, involve a large number of parameters and their optimisation is often a complex and tedious procedure. Artificial intelligence algorithms are proving increasingly useful in such situations. Here, we present an automatic, reliable and scalable numerical optimisation concept based on the canonical genetic algorithm (GA). The algorithm was used to optimise the 3D magnetic field profile of the NSE spectrometer SPAN, at the HMI. We discuss the potential of the GA which combined with the existing Monte-Carlo codes (Vitess, McSTAS, etc.) leads to a very powerful tool for automated global optimisation of a general neutron scattering instrument, avoiding local optimum configurations

  10. Analysis of DTI-Derived Tensor Metrics in Differential Diagnosis between Low-grade and High-grade Gliomas.

    Science.gov (United States)

    Jiang, Liang; Xiao, Chao-Yong; Xu, Quan; Sun, Jun; Chen, Huiyou; Chen, Yu-Chen; Yin, Xindao

    2017-01-01

    Purpose: It is critical and difficult to accurately discriminate between high- and low-grade gliomas preoperatively. This study aimed to ascertain the role of several scalar measures in distinguishing high-grade from low-grade gliomas, especially the axial diffusivity (AD), radial diffusivity (RD), planar tensor (Cp), spherical tensor (Cs), and linear tensor (Cl) derived from diffusion tensor imaging (DTI). Materials and Methods: Fifty-three patients with pathologically confirmed brain gliomas (21 low-grade and 32 high-grade) were included. Contrast-enhanced T1-weighted images and DTI were performed in all patients. The AD, RD, Cp, Cs, and Cl values in the tumor zone, peritumoral edema zone, white matter (WM) adjacent to edema and contralateral normal-appearing white matter (NAWM) were calculated. The DTI parameters and tumor grades were statistically analyzed, and receiver operating characteristic (ROC) curve analysis was also performed. Results: The DTI metrics in the affected hemisphere showed significant differences from those in the NAWM, except for the AD values in the tumor zone and the RD values in WM adjacent to edema in the low-grade groups, as well as the Cp values in WM adjacent to edema in the high-grade groups. AD in the tumor zone as well as Cs and Cl in WM adjacent to edema revealed significant differences between the low- and high-grade gliomas. The areas under the curve (Az) of all three metrics were greater than 0.5 in distinguishing low-grade from high-grade gliomas by ROC curve analysis, and the best DTI metric was Cs in WM adjacent to edema (Az: 0.692). Conclusion: AD in the tumor zone as well as Cs and Cl in WM adjacent to edema will provide additional information to better classify gliomas and can be used as non-invasive reliable biomarkers in glioma grading.

  11. Does the use of hormonal contraceptives cause microstructural changes in cerebral white matter? Preliminary results of a DTI and tractography study.

    Science.gov (United States)

    De Bondt, Timo; Van Hecke, Wim; Veraart, Jelle; Leemans, Alexander; Sijbers, Jan; Sunaert, Stefan; Jacquemyn, Yves; Parizel, Paul M

    2013-01-01

    To evaluate the effect of monophasic combined oral contraceptive pill (COCP) and menstrual cycle phase in healthy young women on white matter (WM) organization using diffusion tensor imaging (DTI). Thirty young women were included in the study; 15 women used COCP and 15 women had a natural cycle. All subjects underwent DTI magnetic resonance imaging during the follicular and luteal phase of their cycle, or in different COCP cycle phases. DTI parameters were obtained in different WM structures by performing diffusion tensor fibre tractography. Fractional anisotropy and mean diffusivity were calculated for different WM structures. Hormonal plasma concentrations were measured in peripheral venous blood samples and correlated with the DTI findings. We found a significant difference in mean diffusivity in the fornix between the COCP and the natural cycle group. Mean diffusivity values in the fornix were negatively correlated with luteinizing hormone and estradiol blood concentrations. An important part in the limbic system, the fornix, regulates emotional processes. Differences in diffusion parameters in the fornix may contribute to behavioural alternations related to COCP use. This finding also suggests that the use of oral contraceptives needs to be taken into account when designing DTI group studies.

  12. Preliminary clinical applications of DTI in human cervical spinal cord

    International Nuclear Information System (INIS)

    Song Ting; Mai Weiwen; Liang Biling; Shen Jun; Huang Suiqiao; Hu Chunhong

    2007-01-01

    Objective: To condcut preliminary study of the value of DTI(diffusion tensor imaging) in human cervical spinal cord. Methods: Twenty-one patients suffering from cervical spondylotic myelopathy and twenty volunteers without any clinical symptoms underwent routine MRI and DTI examination. DTI was performed in six non-collinear directions with single-shot fast spin echo echo, planar imaging sequence(b value = 400 s·mm -2 ). ADC(apparent diffusion coefficient) and FA(fractional anisotropy)values were measured by ROIs(regions of interest) in 4 different level segment spinal cord (C 2/3 , C 3/4 , C 4/5 , C 5/6 ) in normal volunteers, in lesions and normal segmental spinal cord in clinical cases respectively. DTI original images were automatically processed by using IDL (Version 5.6) soft- ware to produce color tensor images. SPSS11.0 software for windows was used for t-test and one-way ANOVA analysis. The difference was considered statistically significant if P 2/3 , C 3/4 , C 4/5 , C 5/6 , were analyzed and it was found that FA value between them had a significant difference by ANOVA, F=159.24, P 2/3 level. However, ADC value between 4 segments had no significant difference(F=2.191, P>0.05). (2)In patients of cervical spondylotic myelopathy, routine MRI T2WI showed abnormal signal in 9 cases, and showed no abnormal signal in 12 dases. In sixteen cases it was found that abnormal patchy green signal on colorized tensor maps appeared on the normal blue spinal cord. Also, in patients of cervical spondylotic myelopathy, there was significant difference in ADC and FA value between lesions and normal spinal cord (paired t test, for ADC, t=2.88, P 2/3 level segment spinal cord in normal volunteers (0.85 ± 0.03) is the highest among other segments. FA value decreases gradually along cervical spinal cord towards the caudal direction. However, the difference of ADC values amongst 4 segments is not significant. DTI colorized tensor maps can show more lesions than routine MRI

  13. A DTI study to probe tumor microstructure and its connection with hypoxia.

    Science.gov (United States)

    Majumdar, Shreyan; Kotecha, Mrignayani; Triplett, William; Epel, Boris; Halpern, Howard

    2014-01-01

    Solid tumors have chaotic organization of blood vessels, disruptive nerve paths and muscle fibers that result in a hostile and heterogeneous microenvironment. These tumor regions are often hypoxic and resistant to radiation therapy. The knowledge of partial pressure of oxygen concentration (pO2), in conjunction with the information about tissue organization, can predict tissue health and may eventually be used in combination with intensity-modulated radiation therapy (IMRT) for targeted destruction of radiation-resistant areas, while sparing healthy tissues. Diffusion tensor imaging (DTI) based parameter fractional anisotropy (FA) can be used to assess organization of tissue microstructure, whereas the pO2 can be measured using electron paramagnetic resonance oxygen imaging (EPROI). This study is our first step to connect these two important physiological parameters. We calculated FA in fixed fibrosarcoma (FSa) grown in hind leg of nude mice (n = 6) using preclinical 9.4 T MRI. The FA in tumor region (0.34 ± 0.014) was found to be lower when compared to normal surrounding region (0.36 ± 0.013). We hypothesized that the change in FA is directly correlated with the change in oxygen concentration in tumor. We present preliminary in vivo results showing a positive correlation (R = 0.85, p = 0.017) between the FA and pO2 values acquired for MCa4 tumor (n = 1) using DTI and EPROI.

  14. Development of model DTY-104 radon measuring meter

    International Nuclear Information System (INIS)

    Shi Zhixia; Zhang Aiming; Li Yachun; Wang Qingheng

    2000-01-01

    Model DTY-104 radon measuring meter is an improvement on Model DTY-103. 'Difference value method' is used, which has been strictly developed and makes the radon exhalation rate more accurate, instead of using 'simplified difference value method'. The electronic circuit is redesigned and 80C31 single chip processor is used, which makes the operation more convenient and the function strengthened. In a more reasonable manner, the humidity sensor is mounted in the collection chamber. The collection efficiency can be automatically corrected. The technique of exchanging the collection mylar reduces the waiting time and improves work efficiency. The apparatus is applied to the measurement of the radon concentration in the environment and the radon exhalation from the surface of the building materials, walls and ground. The lower detection limit is about 4Bq/m 3 for 222 Rn concentration and 5 x 10 -5 Bq/s/m 2 for 222 Rn exhalation rate

  15. DTI Analysis of Presbycusis Using Voxel-Based Analysis.

    Science.gov (United States)

    Ma, W; Li, M; Gao, F; Zhang, X; Shi, L; Yu, L; Zhao, B; Chen, W; Wang, G; Wang, X

    2016-07-14

    Presbycusis is the most common sensory deficit in the aging population. A recent study reported using a DTI-based tractography technique to identify a lack of integrity in a portion of the auditory pathway in patients with presbycusis. The aim of our study was to investigate the white matter pathology of patients with presbycusis by using a voxel-based analysis that is highly sensitive to local intensity changes in DTI data. Fifteen patients with presbycusis and 14 age- and sex-matched healthy controls were scanned on a 3T scanner. Fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity were obtained from the DTI data. Intergroup statistics were implemented on these measurements, which were transformed to Montreal Neurological Institute coordinates by using a nonrigid image registration method called large deformation diffeomorphic metric mapping. Increased axial diffusivity, radial diffusivity, and mean diffusivity and decreased fractional anisotropy were found near the right-side hearing-related areas in patients with presbycusis. Increased radial diffusivity and mean diffusivity were also found near a language-related area (Broca area) in patients with presbycusis. Our findings could be important for exploring reliable imaging evidence of presbycusis and could complement an ROI-based approach. © 2016 American Society of Neuroradiology.

  16. Machine learning for the assessment of Alzheimer's disease through DTI

    Science.gov (United States)

    Lella, Eufemia; Amoroso, Nicola; Bellotti, Roberto; Diacono, Domenico; La Rocca, Marianna; Maggipinto, Tommaso; Monaco, Alfonso; Tangaro, Sabina

    2017-09-01

    Digital imaging techniques have found several medical applications in the development of computer aided detection systems, especially in neuroimaging. Recent advances in Diffusion Tensor Imaging (DTI) aim to discover biological markers for the early diagnosis of Alzheimer's disease (AD), one of the most widespread neurodegenerative disorders. We explore here how different supervised classification models provide a robust support to the diagnosis of AD patients. We use DTI measures, assessing the structural integrity of white matter (WM) fiber tracts, to reveal patterns of disrupted brain connectivity. In particular, we provide a voxel-wise measure of fractional anisotropy (FA) and mean diffusivity (MD), thus identifying the regions of the brain mostly affected by neurodegeneration, and then computing intensity features to feed supervised classification algorithms. In particular, we evaluate the accuracy of discrimination of AD patients from healthy controls (HC) with a dataset of 80 subjects (40 HC, 40 AD), from the Alzheimer's Disease Neurodegenerative Initiative (ADNI). In this study, we compare three state-of-the-art classification models: Random Forests, Naive Bayes and Support Vector Machines (SVMs). We use a repeated five-fold cross validation framework with nested feature selection to perform a fair comparison between these algorithms and evaluate the information content they provide. Results show that AD patterns are well localized within the brain, thus DTI features can support the AD diagnosis.

  17. Human brain functional MRI and DTI visualization with virtual reality.

    Science.gov (United States)

    Chen, Bin; Moreland, John; Zhang, Jingyu

    2011-12-01

    Magnetic resonance diffusion tensor imaging (DTI) and functional MRI (fMRI) are two active research areas in neuroimaging. DTI is sensitive to the anisotropic diffusion of water exerted by its macromolecular environment and has been shown useful in characterizing structures of ordered tissues such as the brain white matter, myocardium, and cartilage. The diffusion tensor provides two new types of information of water diffusion: the magnitude and the spatial orientation of water diffusivity inside the tissue. This information has been used for white matter fiber tracking to review physical neuronal pathways inside the brain. Functional MRI measures brain activations using the hemodynamic response. The statistically derived activation map corresponds to human brain functional activities caused by neuronal activities. The combination of these two methods provides a new way to understand human brain from the anatomical neuronal fiber connectivity to functional activities between different brain regions. In this study, virtual reality (VR) based MR DTI and fMRI visualization with high resolution anatomical image segmentation and registration, ROI definition and neuronal white matter fiber tractography visualization and fMRI activation map integration is proposed. Rationale and methods for producing and distributing stereoscopic videos are also discussed.

  18. A DTI-based tractography study of effects on brain structure associated with prenatal alcohol exposure in newborns

    Science.gov (United States)

    Taylor, Paul A.; Jacobson, Sandra W.; van der Kouwe, André; Molteno, Christopher D.; Chen, Gang; Wintermark, Pia; Alhamud, Alkathafi; Jacobson, Joseph L.; Meintjes, Ernesta M.

    2014-01-01

    Prenatal alcohol exposure is known to have severe, long-term consequences for brain and behavioral development already detectable in infancy and childhood. Resulting features of fetal alcohol spectrum disorders (FASD) include cognitive and behavioral effects, as well as facial anomalies and growth deficits. Diffusion tensor imaging (DTI) and tractography were used to analyze white matter development in 11 newborns (age since conception <45 weeks) whose mothers were recruited during pregnancy. Comparisons were made with 9 age-matched controls born to abstainers or light drinkers from the same Cape Coloured (mixed ancestry) community near Cape Town, South Africa. DTI parameters, T1 relaxation time, proton density and volumes were used to quantify and investigate group differences in white matter (WM) in the newborn brains. Probabilistic tractography was used to estimate and to delineate similar tract locations among the subjects for transcallosal pathways, cortico-spinal projection fibers and cortico-cortical association fibers. In each of these WM networks, the axial diffusivity AD was the parameter that showed the strongest association with maternal drinking. The strongest relations were observed in medial and inferior WM, regions in which the myelination process typically begins. In contrast to studies of older individuals with prenatal alcohol exposure, FA did not exhibit a consistent and significant relation with alcohol exposure. To our knowledge, this is the first DTI-tractography study of prenatally alcohol exposed newborns. PMID:25182535

  19. Design of optimised backstepping controller for the synchronisation of chaotic Colpitts oscillator using shark smell algorithm

    Science.gov (United States)

    Fouladi, Ehsan; Mojallali, Hamed

    2018-01-01

    In this paper, an adaptive backstepping controller has been tuned to synchronise two chaotic Colpitts oscillators in a master-slave configuration. The parameters of the controller are determined using shark smell optimisation (SSO) algorithm. Numerical results are presented and compared with those of particle swarm optimisation (PSO) algorithm. Simulation results show better performance in terms of accuracy and convergence for the proposed optimised method compared to PSO optimised controller or any non-optimised backstepping controller.

  20. Adjoint Optimisation of the Turbulent Flow in an Annular Diffuser

    DEFF Research Database (Denmark)

    Gotfredsen, Erik; Agular Knudsen, Christian; Kunoy, Jens Dahl

    2017-01-01

    In the present study, a numerical optimisation of guide vanes in an annular diffuser, is performed. The optimisation is preformed for the purpose of improving the following two parameters simultaneously; the first parameter is the uniformity perpen-dicular to the flow direction, a 1/3 diameter do...

  1. Computer Based Optimisation Rutines

    DEFF Research Database (Denmark)

    Dragsted, Birgitte; Olsen, Flemmming Ove

    1996-01-01

    In this paper the need for optimisation methods for the laser cutting process has been identified as three different situations. Demands on the optimisation methods for these situations are presented, and one method for each situation is suggested. The adaptation and implementation of the methods...

  2. Layout Optimisation of Wave Energy Converter Arrays

    Directory of Open Access Journals (Sweden)

    Pau Mercadé Ruiz

    2017-08-01

    Full Text Available This paper proposes an optimisation strategy for the layout design of wave energy converter (WEC arrays. Optimal layouts are sought so as to maximise the absorbed power given a minimum q-factor, the minimum distance between WECs, and an area of deployment. To guarantee an efficient optimisation, a four-parameter layout description is proposed. Three different optimisation algorithms are further compared in terms of performance and computational cost. These are the covariance matrix adaptation evolution strategy (CMA, a genetic algorithm (GA and the glowworm swarm optimisation (GSO algorithm. The results show slightly higher performances for the latter two algorithms; however, the first turns out to be significantly less computationally demanding.

  3. A methodological approach to the design of optimising control strategies for sewer systems

    DEFF Research Database (Denmark)

    Mollerup, Ane Loft; Mikkelsen, Peter Steen; Sin, Gürkan

    2016-01-01

    This study focuses on designing an optimisation based control for sewer system in a methodological way and linking itto a regulatory control. Optimisation based design is found to depend on proper choice of a model, formulation of objective function and tuning of optimisation parameters. Accordin......This study focuses on designing an optimisation based control for sewer system in a methodological way and linking itto a regulatory control. Optimisation based design is found to depend on proper choice of a model, formulation of objective function and tuning of optimisation parameters....... Accordingly, two novel optimisation configurations are developed, where the optimisation either acts on the actuators or acts on the regulatory control layer. These two optimisation designs are evaluated on a sub-catchment of the sewer system in Copenhagen, and found to perform better than the existing...

  4. TEM turbulence optimisation in stellarators

    Science.gov (United States)

    Proll, J. H. E.; Mynick, H. E.; Xanthopoulos, P.; Lazerson, S. A.; Faber, B. J.

    2016-01-01

    With the advent of neoclassically optimised stellarators, optimising stellarators for turbulent transport is an important next step. The reduction of ion-temperature-gradient-driven turbulence has been achieved via shaping of the magnetic field, and the reduction of trapped-electron mode (TEM) turbulence is addressed in the present paper. Recent analytical and numerical findings suggest TEMs are stabilised when a large fraction of trapped particles experiences favourable bounce-averaged curvature. This is the case for example in Wendelstein 7-X (Beidler et al 1990 Fusion Technol. 17 148) and other Helias-type stellarators. Using this knowledge, a proxy function was designed to estimate the TEM dynamics, allowing optimal configurations for TEM stability to be determined with the STELLOPT (Spong et al 2001 Nucl. Fusion 41 711) code without extensive turbulence simulations. A first proof-of-principle optimised equilibrium stemming from the TEM-dominated stellarator experiment HSX (Anderson et al 1995 Fusion Technol. 27 273) is presented for which a reduction of the linear growth rates is achieved over a broad range of the operational parameter space. As an important consequence of this property, the turbulent heat flux levels are reduced compared with the initial configuration.

  5. Dose optimisation in single plane interstitial brachytherapy

    DEFF Research Database (Denmark)

    Tanderup, Kari; Hellebust, Taran Paulsen; Honoré, Henriette Benedicte

    2006-01-01

    patients,       treated for recurrent rectal and cervical cancer, flexible catheters were       sutured intra-operatively to the tumour bed in areas with compromised       surgical margin. Both non-optimised, geometrically and graphically       optimised CT -based dose plans were made. The overdose index...... on the       regularity of the implant, such that the benefit of optimisation was       larger for irregular implants. OI and HI correlated strongly with target       volume limiting the usability of these parameters for comparison of dose       plans between patients. CONCLUSIONS: Dwell time optimisation significantly......BACKGROUND AND PURPOSE: Brachytherapy dose distributions can be optimised       by modulation of source dwell times. In this study dose optimisation in       single planar interstitial implants was evaluated in order to quantify the       potential benefit in patients. MATERIAL AND METHODS: In 14...

  6. Regionalisation of a distributed method for flood quantiles estimation: Revaluation of local calibration hypothesis to enhance the spatial structure of the optimised parameter

    Science.gov (United States)

    Odry, Jean; Arnaud, Patrick

    2016-04-01

    The SHYREG method (Aubert et al., 2014) associates a stochastic rainfall generator and a rainfall-runoff model to produce rainfall and flood quantiles on a 1 km2 mesh covering the whole French territory. The rainfall generator is based on the description of rainy events by descriptive variables following probability distributions and is characterised by a high stability. This stochastic generator is fully regionalised, and the rainfall-runoff transformation is calibrated with a single parameter. Thanks to the stability of the approach, calibration can be performed against only flood quantiles associated with observated frequencies which can be extracted from relatively short time series. The aggregation of SHYREG flood quantiles to the catchment scale is performed using an areal reduction factor technique unique on the whole territory. Past studies demonstrated the accuracy of SHYREG flood quantiles estimation for catchments where flow data are available (Arnaud et al., 2015). Nevertheless, the parameter of the rainfall-runoff model is independently calibrated for each target catchment. As a consequence, this parameter plays a corrective role and compensates approximations and modelling errors which makes difficult to identify its proper spatial pattern. It is an inherent objective of the SHYREG approach to be completely regionalised in order to provide a complete and accurate flood quantiles database throughout France. Consequently, it appears necessary to identify the model configuration in which the calibrated parameter could be regionalised with acceptable performances. The revaluation of some of the method hypothesis is a necessary step before the regionalisation. Especially the inclusion or the modification of the spatial variability of imposed parameters (like production and transfer reservoir size, base flow addition and quantiles aggregation function) should lead to more realistic values of the only calibrated parameter. The objective of the work presented

  7. Optimised Renormalisation Group Flows

    CERN Document Server

    Litim, Daniel F

    2001-01-01

    Exact renormalisation group (ERG) flows interpolate between a microscopic or classical theory and the corresponding macroscopic or quantum effective theory. For most problems of physical interest, the efficiency of the ERG is constrained due to unavoidable approximations. Approximate solutions of ERG flows depend spuriously on the regularisation scheme which is determined by a regulator function. This is similar to the spurious dependence on the ultraviolet regularisation known from perturbative QCD. Providing a good control over approximated ERG flows is at the root for reliable physical predictions. We explain why the convergence of approximate solutions towards the physical theory is optimised by appropriate choices of the regulator. We study specific optimised regulators for bosonic and fermionic fields and compare the optimised ERG flows with generic ones. This is done up to second order in the derivative expansion at both vanishing and non-vanishing temperature. An optimised flow for a ``proper-time ren...

  8. Optimisation of the LHCb detector

    CERN Document Server

    Hierck, R H

    2003-01-01

    This thesis describes a comparison of the LHCb classic and LHCb light concept from a tracking perspective. The comparison includes the detector occupancies, the various pattern recognition algorithms and the reconstruction performance. The final optimised LHCb setup is used to study the physics performance of LHCb for the Bs->DsK and Bs->DsPi decay channels. This includes both the event selection and a study of the sensitivity for the Bs oscillation frequency, delta m_s, the Bs lifetime difference, DGamma_s, and the CP parameter gamma-2delta gamma.

  9. Methods for Optimisation of the Laser Cutting Process

    DEFF Research Database (Denmark)

    Dragsted, Birgitte

    This thesis deals with the adaptation and implementation of various optimisation methods, in the field of experimental design, for the laser cutting process. The problem in optimising the laser cutting process has been defined and a structure for at Decision Support System (DSS......) for the optimisation of the laser cutting process has been suggested. The DSS consists of a database with the currently used and old parameter settings. Also one of the optimisation methods has been implemented in the DSS in order to facilitate the optimisation procedure for the laser operator. The Simplex Method has...... been adapted in two versions. A qualitative one, that by comparing the laser cut items optimise the process and a quantitative one that uses a weighted quality response in order to achieve a satisfactory quality and after that maximises the cutting speed thus increasing the productivity of the process...

  10. Design Optimisation and Conrol of a Pilot Operated Seat Valve

    DEFF Research Database (Denmark)

    Nielsen, Brian; Andersen, Torben Ole; Hansen, Michael Rygaard

    2004-01-01

    The paper gives an approach for optimisation of the bandwidth of a pilot operated seat valve for mobile applications. Physical dimensions as well as parameters of the implemented control loop are optimised simultaneously. The frequency response of the valve varies as a function of the pressure drop...

  11. Histological validation of high-resolution DTI in human post mortem tissue

    NARCIS (Netherlands)

    Seehaus, A.; Roebroeck, A.; Bastiani, M.; Fonseca, L.; Bratzke, H.; Lori, N.; Vilanova, A.; Goebel, R.; Galuske, R.

    2015-01-01

    Diffusion tensor imaging (DTI) is amongst the simplest mathematical models available for diffusion magnetic resonance imaging, yet still by far the most used one. Despite the success of DTI as an imaging tool for white matter fibers, its anatomical underpinnings on a microstructural basis remain

  12. Evaluation of skeletal muscle DTI in patients with duchenne muscular dystrophy

    NARCIS (Netherlands)

    Hooijmans, M. T.; Damon, B. M.; Froeling, M.; Versluis, M. J.; Burakiewicz, J.; Verschuuren, J. J G M; Niks, E. H.; Webb, A. G.; Kan, H. E.

    2015-01-01

    Diffusion tensor imaging (DTI) is a popular method to assess differences in fiber organization in diseased and healthy muscle tissue. Previous work has shown that muscle DTI measurements depend on signal-to-noise ratio (SNR), %fat, and tissue T2. The goal of this study was to evaluate the potential

  13. White matter mapping by DTI-based tractography for neurosurgery

    International Nuclear Information System (INIS)

    Kamada, Kyousuke

    2009-01-01

    To validate the corticospinal tract (CST) and arcuate fasciculus (AF) illustrated by diffusion tensor imaging (DTI), we used CST- and AF-tractography integrated neuronavigation and monopolar and bipolar direct fiber stimulation. Forty seven patients with brain lesions adjacent to the CST and AF were studied. During lesion resection, direct fiber stimulation was applied to the CST and AF to elicit motor responses (fiber-motor evoked potential (MEP)) and the impairment of language-related functions to identify the CST and AF. The minimum distance between the resection border and illustrated CST was measured on postoperative images. Direct fiber stimulation demonstrated that CST- and AF-tractography accurately reflected anatomical CST functioning. The cortical stimulation to the gyrus, including the language-functional MRI (fMRI) activation, evoked speech arrest, while the subcortical stimulation close to the AF reproducibly caused 'paranomia' without speech arrest. There were strong correlations between stimulus intensity for the fiber-MEP and the distance between eloquent fibers and the stimulus points. The convergent calculation formulated 1.8 mA as the electrical threshold of CST for the fiber-MEP, which was much smaller than that of the hand motor area. Validated tractography demonstrated the mean distance and intersection angle between CST and AF were 5 mm and 107 deg, respectively. In addition, the anisotropic diffusion-weighted image (ADWI) and CST-tractography clearly indicated the locations of the primary motor area (PMA) and the central sulcus and well reflected the anatomical characteristics of the corticospinal tract in the human brain. DTI-based tractography is a reliable way to map the white matter connections in the entire brain in clinical and basic neuroscience. By combining these techniques, investigating the cortico-subcortical connections in the human central nervous system could contribute to elucidating the neural networks of the human brain and

  14. White matter mapping by DTI-based tractography for neurosurgery

    International Nuclear Information System (INIS)

    Kamada, Kyousuke

    2011-01-01

    The purpose of this study was to validate the corticospinal tract (CST) and arcuate fasciculus (AF) illustrated by diffusion tensor imaging (DTI), we used CST- and AF-tractography integrated neuronavigation and monopolar and bipolar direct fiber stimulation. Forty seven patients with brain lesions adjacent to the CST and AF were studied. During lesion resection, direct fiber stimulation was applied to the CST and AF to elicit motor responses (fiber-MEP) and the impairment of language-related functions to identify the CST and AF. The minimum distance between the resection border and illustrated CST was measured on postoperative images. Direct fiber stimulation demonstrated that CST- and AF-tractography accurately reflected anatomical CST functioning. The cortical stimulation to the gyrus, including the language-fMRI activation, evoked speech arrest, while the subcortical stimulation close to the AF reproducibly caused 'paranomia' without speech arrest. There were strong correlations between stimulus intensity for the fiber-MEP and the distance between eloquent fibers and the stimulus points. The convergent calculation formulated 1.8 mA as the electrical threshold of CST for the fiber-MEP, which was much smaller than that of the hand motor area. Validated tractography demonstrated the mean distance and intersection angle between CST and AF were 5 mm and 107 deg, respectively. In addition, the anisotropic diffusion-weighted image (ADWI) and CST-tractography clearly indicated the locations of the primary motor area (PMA) and the central sulcus and well reflected the anatomical characteristics of the corticospinal tract in the human brain. DTI-based tractography is a reliable way to map the white matter connections in the entire brain in clinical and basic neuroscience. By combining these techniques, investigating the cortico-subcortical connections in the human central nervous system could contribute to elucidating the neural networks of the human brain and shed light

  15. Functional imaging for brain tumors (perfusion, DTI and MR spectroscopy)

    International Nuclear Information System (INIS)

    Essig, M.; Giesel, F.; Stieltjes, B.; Weber, M.A.

    2007-01-01

    This contribution considers the possibilities involved with using functional methods in magnetic resonance imaging (MRI) diagnostics for brain tumors. Of the functional methods available, we discuss perfusion MRI (PWI), diffusion MRI (DWI and DTI) and MR spectroscopy (H-MRS). In cases of brain tumor, PWI aids in grading and better differentiation in diagnostics as well as for pre-therapeutic planning. In addition, the course of treatment, both after chemo- as well as radiotherapy in combination with surgical treatment, can be optimized. PWI allows better estimates of biological activity and aggressiveness in low grade brain tumors, and in the case of WHO grade II astrocytoma showing anaplastically transformed tumor areas, allows more rapid visualization and a better prediction of the course of the disease than conventional MRI diagnostics. Diffusion MRI, due to the directional dependence of the diffusion, can illustrate the course and direction of the nerve fibers, as well as reconstructing the nerve tracts in the cerebrum, pons and cerebellum 3-dimensionally. Diffusion imaging can be used for describing brain tumors, for evaluating contralateral involvement and the course of the nerve fibers near the tumor. Due to its operator dependence, DTI based fiber tracking for defining risk structures is controversial. DWI can also not differentiate accurately between cystic and necrotic brain tumors, or between metastases and brain abscesses. H-MRS provides information on cell membrane metabolism, neuronal integrity and the function of neuronal structures, energy metabolism and the formation of tumors and brain tissue necroses. Diagnostic problems such as the differentiation between neoplastic and non-neoplastic lesions, grading cerebral glioma and distinguishing between primary brain tumors and metastases can be resolved. An additional contribution will discuss the control of the course of glial tumors after radiotherapy. (orig.)

  16. Parameter Optimisation and Uncertainty Analysis in Visual MODFLOW based Flow Model for predicting the groundwater head in an Eastern Indian Aquifer

    Science.gov (United States)

    Mohanty, B.; Jena, S.; Panda, R. K.

    2016-12-01

    The overexploitation of groundwater elicited in abandoning several shallow tube wells in the study Basin in Eastern India. For the sustainability of groundwater resources, basin-scale modelling of groundwater flow is indispensable for the effective planning and management of the water resources. The basic intent of this study is to develop a 3-D groundwater flow model of the study basin using the Visual MODFLOW Flex 2014.2 package and successfully calibrate and validate the model using 17 years of observed data. The sensitivity analysis was carried out to quantify the susceptibility of aquifer system to the river bank seepage, recharge from rainfall and agriculture practices, horizontal and vertical hydraulic conductivities, and specific yield. To quantify the impact of parameter uncertainties, Sequential Uncertainty Fitting Algorithm (SUFI-2) and Markov chain Monte Carlo (McMC) techniques were implemented. Results from the two techniques were compared and the advantages and disadvantages were analysed. Nash-Sutcliffe coefficient (NSE), Coefficient of Determination (R2), Mean Absolute Error (MAE), Mean Percent Deviation (Dv) and Root Mean Squared Error (RMSE) were adopted as criteria of model evaluation during calibration and validation of the developed model. NSE, R2, MAE, Dv and RMSE values for groundwater flow model during calibration and validation were in acceptable range. Also, the McMC technique was able to provide more reasonable results than SUFI-2. The calibrated and validated model will be useful to identify the aquifer properties, analyse the groundwater flow dynamics and the change in groundwater levels in future forecasts.

  17. Bi-modal stimulation in the treatment of tinnitus: a study protocol for an exploratory trial to optimise stimulation parameters and patient subtyping.

    Science.gov (United States)

    D'Arcy, Shona; Hamilton, Caroline; Hughes, Stephen; Hall, Deborah A; Vanneste, Sven; Langguth, Berthold; Conlon, Brendan

    2017-10-25

    Tinnitus is the perception of sound in the absence of a corresponding external acoustic stimulus. Bimodal neuromodulation is emerging as a promising treatment for this condition. The main objectives of this study are to investigate the relevance of interstimulus timing and the choices of acoustic and tongue stimuli for a proprietary bimodal (auditory and somatosensory) neuromodulation device, as well as to explore whether specific subtypes of patients are differentially responsive to this novel intervention for reducing the symptoms of chronic tinnitus. This is a two-site, randomised, triple-blind, exploratory study of a proprietary neuromodulation device with a pre-post and 12-month follow-up design. Three different bimodal stimulation parameter sets will be examined. The study will enrol 342 patients, split 80:20 between two sites (Dublin, Ireland and Regensburg, Germany), to complete 12 weeks of treatment with the device. Patients will be allocated to one of three arms using a stepwise stratification according to four binary categories: tinnitus tonality, sound level tolerance (using loudness discomfort level of Tinnitus Handicap Inventory and the Tinnitus Functional Index, after 12 weeks of intervention. Clinical efficacy will be further explored in a series of patient subtypes, split by the stratification variables and by presence of a somatic tinnitus. Evidence for sustained effects on the psychological and functional impact of tinnitus will be followed up for 12 months. Safety data will be collected and reported. A number of feasibility measures to inform future trial design include: reasons for exclusion, completeness of data collection, attrition rates, patient's adherence to the device usage as per manufacturer's instructions and evaluation of alternative methods for estimating tinnitus impact and tinnitus loudness. This study protocol is approved by the Tallaght Hospital/St. James's Hospital Joint Research Ethics Committee in Dublin, Ireland, and by the

  18. Optimising Magnetostatic Assemblies

    DEFF Research Database (Denmark)

    Insinga, Andrea Roberto; Smith, Anders

    theorem. This theorem formulates an energy equivalence principle with several implications concerning the optimisation of objective functionals that are linear with respect to the magnetic field. Linear functionals represent different optimisation goals, e.g. maximising a certain component of the field...... approached employing a heuristic algorithm, which led to new design concepts. Some of the procedures developed for linear objective functionals have been extended to non-linear objectives, by employing iterative techniques. Even though most the optimality results discussed in this work have been derived...

  19. Weight Optimisation of Steel Monopile Foundations for Offshore Windfarms

    DEFF Research Database (Denmark)

    Fog Gjersøe, Nils; Bouvin Pedersen, Erik; Kristensen, Brian

    2015-01-01

    The potential for mass reduction of monopiles in offshore windfarms using current design practice is investigated. Optimisation by sensitivity analysis is carried out for the following important parameters: wall thickness distribution between tower and monopile, soil stiffness, damping ratio...

  20. Optimising imaging parameters in experimental spiral CT

    International Nuclear Information System (INIS)

    Tiitola, M.; Vehmas, T.; Kivisaari, R.P.; Kivisaari, L.

    1997-01-01

    Purpose: This in vitro study was conducted to analyse lesion detection and relative radiation exposure in different CT techniques. Material and Methods: We used a plastic phantom (12 x 8 x 2 cm) containing holes filled with air or fluid of varying densities to simulate lesions. This was imaged with Siemens Somatom Plus S and GE High Speed Advantage units. We varied table feeds (3 and 6 mm/s in Siemens and 3 and 4.5 mm/s in GE) and increments (2 mm and 4 mm) while keeping collimation at 3 mm. The SmartScan program of GE and the reformating algorithm of Siemens were also analysed. To evaluate the different methods, the phatnom lesions were counted by 3 observers. Radiation exposures associated with each technique were also measured. Results: The images reformatted to a coronal direction were significantly inferior (p<0.01) to those in other techniques. The use of SmartScan did not influence lesion detection, nor did changes in pitch or increment. Spiral and non-spiral techniques proved to be equal. Radiation exposure was lowest when a greater pitch or the SmartScan program was used. Conclusion: Radiation exposure in CT can be limited without significantly impairing the image quality by using low-dose techniques. Reformatting to a coronal direction should be used with care as it debases the image quality. (orig.)

  1. Optimising window parameters for energy efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Boland, J. [South Australia Univ., Adelaide, SA (Australia); Luther, M. [Deakin Univ., Geelong, VIC (Australia)

    1996-12-31

    Large north facing windows act a solar collectors, with the heat being stored in the building mass and being released later in the day. This study examines one of the elements of this paradigm, that increasing the size of equatorially facing windows necessarily improves the energy efficiency of a dwelling. This question and that of whether there is a case for using double glazing in Australia were examined for a number of locations ranging from cool temperate to warm temperate and for several types of construction from lightweight to heavyweight. Simulations were performed using the modelling tool Cheetah. It was found that the optimal window size on equatorially facing walls was smaller than expected for singly glazed windows. Double glazing was found to be effective in most situations and increased the optimum size of the window substantially. Changing the operational pattern of the house (specifically when cooling equipment may be employed) considerably affects conclusions about single and double glazing. (author). 3 tabs., 3 figs., 13 refs.

  2. DTI fiber tractography of cerebro-cerebellar pathways and clinical evaluation of ataxia in childhood posterior fossa tumor survivors.

    Science.gov (United States)

    Oh, Myung Eun; Driever, Pablo Hernáiz; Khajuria, Rajiv K; Rueckriegel, Stefan Mark; Koustenis, Elisabeth; Bruhn, Harald; Thomale, Ulrich-Wilhelm

    2017-01-01

    Pediatric posterior fossa (PF) tumor survivors experience long-term motor deficits. Specific cerebrocerebellar connections may be involved in incidence and severity of motor dysfunction. We examined the relationship between long-term ataxia as well as fine motor function and alteration of differential cerebellar efferent and afferent pathways using diffusion tensor imaging (DTI) and tractography. DTI-based tractography was performed in 19 patients (10 pilocytic astrocytoma (PA) and 9 medulloblastoma patients (MB)) and 20 healthy peers. Efferent Cerebello-Thalamo-Cerebral (CTC) and afferent Cerebro-Ponto-Cerebellar (CPC) tracts were reconstructed and analyzed concerning fractional anisotropy (FA) and volumetric measurements. Clinical outcome was assessed with the International Cooperative Ataxia Rating Scale (ICARS). Kinematic parameters of fine motor function (speed, automation, variability, and pressure) were obtained by employing a digitizing graphic tablet. ICARS scores were significantly higher in MB patients than in PA patients. Poorer ICARS scores and impaired fine motor function correlated significantly with volume loss of CTC pathway in MB patients, but not in PA patients. Patients with pediatric post-operative cerebellar mutism syndrome showed higher loss of CTC pathway volume and were more atactic. CPC pathway volume was significantly reduced in PA patients, but not in MB patients. Neither relationship was observed between the CPC pathway and ICARS or fine motor function. There was no group difference of FA values between the patients and healthy peers. Reduced CTC pathway volumes in our cohorts were associated with severity of long-term ataxia and impaired fine motor function in survivors of MBs. We suggest that the CTC pathway seems to play a role in extent of ataxia and fine motor dysfunction after childhood cerebellar tumor treatment. DTI may be a useful tool to identify relevant structures of the CTC pathway and possibly avoid surgically induced long

  3. Using response surface methodology in optimisation of biodiesel production via alkali catalysed transesterification of waste cooking oil

    CSIR Research Space (South Africa)

    Naidoo, R

    2016-03-01

    Full Text Available The report focuses on optimisation of alkali catalysis as a process for producing biodiesel from waste cooking oils. Biodiesel production parameters that were optimised were methanol to oil ratio, catalyst concentration, reaction temperature...

  4. A pilot DTI analysis in patients with recent onset post-traumatic stress disorder

    Science.gov (United States)

    Liu, Yang; Li, Liang; Li, Baojuan; Zhang, Xi; Lu, Hongbing

    2016-03-01

    To explore the alteration in white matter between survivors with recent onset post-traumatic stress disorder (PTSD) and without PTSD, who survived from the same coal mine flood disaster, the diffusion tensor imaging (DTI) sequences were analyzed using DTI studio and statistical parametric mapping (SPM) packages in this paper. From DTI sequence, the fractional anisotropy (FA) value describes the degree of anisotropy of a diffusion process, while the apparent diffusion coefficient (ADC) value reflects the magnitude of water diffusion. The DTI analyses between PTSD and non-PTSD indicate lower FA values in the right caudate nucleus, right middle temporal gyrus, right fusiform gyrus, and right superior temporal gyrus, and higher ADC values in the right superior temporal gyrus and right corpus callosum of the subjects with PTSD. These results are partly in line with our previous volume and cortical thickness analyses, indicating the importance of multi-modality analysis for PTSD.

  5. Optimisation of radiation protection

    International Nuclear Information System (INIS)

    1988-01-01

    Optimisation of radiation protection is one of the key elements in the current radiation protection philosophy. The present system of dose limitation was issued in 1977 by the International Commission on Radiological Protection (ICRP) and includes, in addition to the requirements of justification of practices and limitation of individual doses, the requirement that all exposures be kept as low as is reasonably achievable, taking social and economic factors into account. This last principle is usually referred to as optimisation of radiation protection, or the ALARA principle. The NEA Committee on Radiation Protection and Public Health (CRPPH) organised an ad hoc meeting, in liaison with the NEA committees on the safety of nuclear installations and radioactive waste management. Separate abstracts were prepared for individual papers presented at the meeting

  6. Optimisation by hierarchical search

    Science.gov (United States)

    Zintchenko, Ilia; Hastings, Matthew; Troyer, Matthias

    2015-03-01

    Finding optimal values for a set of variables relative to a cost function gives rise to some of the hardest problems in physics, computer science and applied mathematics. Although often very simple in their formulation, these problems have a complex cost function landscape which prevents currently known algorithms from efficiently finding the global optimum. Countless techniques have been proposed to partially circumvent this problem, but an efficient method is yet to be found. We present a heuristic, general purpose approach to potentially improve the performance of conventional algorithms or special purpose hardware devices by optimising groups of variables in a hierarchical way. We apply this approach to problems in combinatorial optimisation, machine learning and other fields.

  7. UK DTI wind programme area - review and current priorities

    International Nuclear Information System (INIS)

    Craig, J.W.

    1998-01-01

    The Wind Energy programme commenced in 1979 initially to determine the technical and economic feasibility of the technology. Since that time the programme has progressed from research, development and assessment to commercial deployment. It now provides a technology push to complement the market pull created by the Non-Fossil Fuel Obligation (NFFO). Over 280 MW of capacity has now been commissioned. The wind energy programme, is based upon a five year strategy in common with other DTI renewable energy technologies, which were outlined in Energy Paper 62. The programme has four key aims: 1. To encourage the uptake of wind energy. 2. To encourage internationally competitive industries to develop and utilise capabilities for the domestic and export markets. 3. To quantify environmental improvements and disbenefits associated with wind energy. 4. To manage the programme effectively. During the mid 1980s and early 1990s the programme concentrated on technology development and demonstration, which has helped to establish UK expertise in wind energy. Non-technical barriers such as planning have been addressed but are now largely for the industry to resolve. The development of wind turbine technology and related components is aimed at meeting the challenge of both the domestic and world markets. The ability of the DTI programme to meet these challenges is partly dependent on the technical ability and commercially acumen of British companies and partly on the level of support offered by Government. The programme budget has fallen from Pound8.7M/year in 1992/93 to current level of Pound1.4M/year and is yet to fall further. It should be stressed that the decline in budgets followed a review of the Renewables Programme in 1995 which affected all technologies. The wind programme budget was reduced substantially at that time which resulted in a revision of priorities. Continued support for market enablement measures was reduced partly because the industry, supported by the NFFO

  8. DTI and VBM reveal white matter changes without associated gray matter changes in patients with idiopathic restless legs syndrome

    Science.gov (United States)

    Belke, Marcus; Heverhagen, Johannes T; Keil, Boris; Rosenow, Felix; Oertel, Wolfgang H; Stiasny-Kolster, Karin; Knake, Susanne; Menzler, Katja

    2015-01-01

    Background and Purpose We evaluated cerebral white and gray matter changes in patients with iRLS in order to shed light on the pathophysiology of this disease. Methods Twelve patients with iRLS were compared to 12 age- and sex-matched controls using whole-head diffusion tensor imaging (DTI) and voxel-based morphometry (VBM) techniques. Evaluation of the DTI scans included the voxelwise analysis of the fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD). Results Diffusion tensor imaging revealed areas of altered FA in subcortical white matter bilaterally, mainly in temporal regions as well as in the right internal capsule, the pons, and the right cerebellum. These changes overlapped with changes in RD. Voxel-based morphometry did not reveal any gray matter alterations. Conclusions We showed altered diffusion properties in several white matter regions in patients with iRLS. White matter changes could mainly be attributed to changes in RD, a parameter thought to reflect altered myelination. Areas with altered white matter microstructure included areas in the internal capsule which include the corticospinal tract to the lower limbs, thereby supporting studies that suggest changes in sensorimotor pathways associated with RLS. PMID:26442748

  9. DTI study of Children with Congenital Hydrocephalus: 1 Year Post-Surgical Outcomes

    Science.gov (United States)

    Mangano, Francesco T.; Altaye, Mekibib; McKinstry, Robert C.; Shimony, Joshua S.; Powell, Stephanie K.; Phillips, Jannel M.; Barnard, Holly; Limbrick, David D.; Holland, Scott K.; Jones, Blaise V.; Dodd, Jonathon; Simpson, Sarah; Deanna, Mercer; Rajagopal, Akila; Bidwell, Sarah; Yuan, Weihong

    2016-01-01

    Object To investigate white matter structural abnormalities using diffusion tensor imaging (DTI) in children with hydrocephalus before CSF diversionary surgery (including ventriculoperitoneal shunting and endoscopic third ventriculoscopy) and the course of recovery post-surgery in association with neuropsychological and behavioral outcome. Methods This was a prospective study that included 54 children with congenital hydrocephalus (21F/33M; age range: 0.03–194.5 months) who underwent surgery and 64 normal controls (30F/34M, age range: 0.30–197.75 months). DTI and neurodevelopmental outcome data were collected once in the control group and at pre-surgery, 3-month, and 12-month post-surgery in the patients. DTI measures, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) values were extracted from the genu of corpus callosum (gCC) and the posterior limb of internal capsule (PLIC). Group analysis was performed first cross-sectionally to quantify DTI abnormalities at three time points by comparing the controls and the patients group at the three time points separately. Longitudinal comparisons were conducted pairwise between different time points in patients whose data were acquired at multiple time points. Neurodevelopmental data were collected and analyzed using the Adaptive Behavior Assessment System, Second Edition (ABAS-II) and the Bayley Scales of Infant Development, Third Edition (Bayley-III). Correlation analyses were performed between DTI and behavioral outcomes. Results Significant DTI abnormalities were found in both the gCC (lower FA and higher MD, AD, and RD) and the PLIC (higher FA, lower AD and RD) at pre-surgery. The DTI measures in the gCC remained mostly abnormal at 3-month and 12-month post-surgery. The DTI abnormalities in the PLIC were significant in FA and AD at 3-month post-surgery but did nor persist when tested at 12-month post-surgery. Significant longitudinal DTI changes in the

  10. Assessment of brain maturation in the preterm infants using diffusion tensor imaging (DTI) and enhanced T2 star weighted angiography (ESWAN)

    International Nuclear Information System (INIS)

    Ling, Xueying; Tang, Wen; Liu, Guosheng; Huang, Li; Li, Bingxiao; Li, Xiaofei; Liu, Sirun; Xu, Jing

    2013-01-01

    Purpose: To assess the brain maturation of preterm infants using diffusion tensor imaging (DTI) and enhanced T2 star weighted angiography (ESWAN). Materials and methods: Conventional magnetic resonance imaging (MRI), DTI and ESWAN were performed in 60 preterm infants and 21 term controls. 60 preterm infants were subgrouped to two groups according to the age at imaging: before and at term-equivalent age (TEA). Fractional anisotropy (FA), apparent diffusion coefficient (ADC) map from DTI, T 2 * and R 2 * maps from ESWAN were post-processed at an off-line workstation. The values of FA, ADC, T 2 * and R 2 * from the posterior limb of internal capsule (PLIC), frontal white matter (FWM), occipital white matter (OWM) and lentiform nuclei (LN) were determined. These parameters were compared between preterm and term infants. Correlations of DTI and ESWAN parameters with the gestational age, postmenstrual age and postnatal age were analyzed. Results: ADCs of FWM, OWM and LN, and T 2 * values of the PLIC and LN were higher in the preterm infants at TEA compared with the term controls. The correlations were existed between the postmenstrual age and the values of FA, ADC, T 2 *, R 2 * from the PLIC, values of ADC, T 2 *, R 2 * from the LN, T 2 * value from the OWM. The correlations were also found between the postnatal age and the values of FA, ADC, T 2 * from the PLIC, and T 2 * value from the LN. Conclusion: The maturity of preterm brain around TEA was different from that of term controls and appeared to be independent of the prematurity at birth. T 2 * was one of valuable indices to evaluate brain maturation in preterm infants

  11. Assessment of brain maturation in the preterm infants using diffusion tensor imaging (DTI) and enhanced T2 star weighted angiography (ESWAN)

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Xueying, E-mail: lingxuey@163.com [Department of Medical Imaging Center, the First Affiliated Hospital, Jinan University, Guangzhou (China); Tang, Wen [Department of Medical Imaging Center, the First Affiliated Hospital, Jinan University, Guangzhou (China); Liu, Guosheng [Neonatal Intensive Care Unit, the First Affiliated Hospital, Jinan University, Guangzhou (China); Huang, Li [Department of Medical Imaging Center, the First Affiliated Hospital, Jinan University, Guangzhou (China); Li, Bingxiao [Neonatal Intensive Care Unit, the First Affiliated Hospital, Jinan University, Guangzhou (China); Li, Xiaofei; Liu, Sirun [Department of Medical Imaging Center, the First Affiliated Hospital, Jinan University, Guangzhou (China); Xu, Jing [Neonatal Intensive Care Unit, the First Affiliated Hospital, Jinan University, Guangzhou (China)

    2013-09-15

    Purpose: To assess the brain maturation of preterm infants using diffusion tensor imaging (DTI) and enhanced T2 star weighted angiography (ESWAN). Materials and methods: Conventional magnetic resonance imaging (MRI), DTI and ESWAN were performed in 60 preterm infants and 21 term controls. 60 preterm infants were subgrouped to two groups according to the age at imaging: before and at term-equivalent age (TEA). Fractional anisotropy (FA), apparent diffusion coefficient (ADC) map from DTI, T{sub 2}* and R{sub 2}* maps from ESWAN were post-processed at an off-line workstation. The values of FA, ADC, T{sub 2}* and R{sub 2}* from the posterior limb of internal capsule (PLIC), frontal white matter (FWM), occipital white matter (OWM) and lentiform nuclei (LN) were determined. These parameters were compared between preterm and term infants. Correlations of DTI and ESWAN parameters with the gestational age, postmenstrual age and postnatal age were analyzed. Results: ADCs of FWM, OWM and LN, and T{sub 2}* values of the PLIC and LN were higher in the preterm infants at TEA compared with the term controls. The correlations were existed between the postmenstrual age and the values of FA, ADC, T{sub 2}*, R{sub 2}* from the PLIC, values of ADC, T{sub 2}*, R{sub 2}* from the LN, T{sub 2}* value from the OWM. The correlations were also found between the postnatal age and the values of FA, ADC, T{sub 2}* from the PLIC, and T{sub 2}* value from the LN. Conclusion: The maturity of preterm brain around TEA was different from that of term controls and appeared to be independent of the prematurity at birth. T{sub 2}* was one of valuable indices to evaluate brain maturation in preterm infants.

  12. How to apply the Score-Function method to standard discrete event simulation tools in order to optimise a set of system parameters simultaneously: A Job-Shop example will be discussed

    DEFF Research Database (Denmark)

    Nielsen, Erland Hejn

    2000-01-01

    During the last 1-2 decades, simulation optimisation of discrete event dynamic systems (DEDS) has made considerable theoretical progress with respect to computational efficiency. The score-function (SF) method and the infinitesimal perturbation analysis (IPA) are two candidates belonging to this ...

  13. Advanced optimisation - coal fired power plant operations

    Energy Technology Data Exchange (ETDEWEB)

    Turney, D.M.; Mayes, I. [E.ON UK, Nottingham (United Kingdom)

    2005-03-01

    The purpose of this unit optimization project is to develop an integrated approach to unit optimisation and develop an overall optimiser that is able to resolve any conflicts between the individual optimisers. The individual optimisers have been considered during this project are: on-line thermal efficiency package, GNOCIS boiler optimiser, GNOCIS steam side optimiser, ESP optimisation, and intelligent sootblowing system. 6 refs., 7 figs., 3 tabs.

  14. Optimisation in radiotherapy II: Programmed and inversion optimisation algorithms

    International Nuclear Information System (INIS)

    Ebert, M.

    1997-01-01

    This is the second article in a three part examination of optimisation in radiotherapy. The previous article established the bases of optimisation in radiotherapy, and the formulation of the optimisation problem. This paper outlines several algorithms that have been used in radiotherapy, for searching for the best irradiation strategy within the full set of possible strategies. Two principle classes of algorithm are considered - those associated with mathematical programming which employ specific search techniques, linear programming type searches or artificial intelligence - and those which seek to perform a numerical inversion of the optimisation problem, finishing with deterministic iterative inversion. (author)

  15. Robustness analysis of bogie suspension components Pareto optimised values

    Science.gov (United States)

    Mousavi Bideleh, Seyed Milad

    2017-08-01

    Bogie suspension system of high speed trains can significantly affect vehicle performance. Multiobjective optimisation problems are often formulated and solved to find the Pareto optimised values of the suspension components and improve cost efficiency in railway operations from different perspectives. Uncertainties in the design parameters of suspension system can negatively influence the dynamics behaviour of railway vehicles. In this regard, robustness analysis of a bogie dynamics response with respect to uncertainties in the suspension design parameters is considered. A one-car railway vehicle model with 50 degrees of freedom and wear/comfort Pareto optimised values of bogie suspension components is chosen for the analysis. Longitudinal and lateral primary stiffnesses, longitudinal and vertical secondary stiffnesses, as well as yaw damping are considered as five design parameters. The effects of parameter uncertainties on wear, ride comfort, track shift force, stability, and risk of derailment are studied by varying the design parameters around their respective Pareto optimised values according to a lognormal distribution with different coefficient of variations (COVs). The robustness analysis is carried out based on the maximum entropy concept. The multiplicative dimensional reduction method is utilised to simplify the calculation of fractional moments and improve the computational efficiency. The results showed that the dynamics response of the vehicle with wear/comfort Pareto optimised values of bogie suspension is robust against uncertainties in the design parameters and the probability of failure is small for parameter uncertainties with COV up to 0.1.

  16. Multiobjective optimisation of bogie suspension to boost speed on curves

    Science.gov (United States)

    Milad Mousavi-Bideleh, Seyed; Berbyuk, Viktor

    2016-01-01

    To improve safety and maximum admissible speed on different operational scenarios, multiobjective optimisation of bogie suspension components of a one-car railway vehicle model is considered. The vehicle model has 50 degrees of freedom and is developed in multibody dynamics software SIMPACK. Track shift force, running stability, and risk of derailment are selected as safety objective functions. The improved maximum admissible speeds of the vehicle on curves are determined based on the track plane accelerations up to 1.5 m/s2. To attenuate the number of design parameters for optimisation and improve the computational efficiency, a global sensitivity analysis is accomplished using the multiplicative dimensional reduction method (M-DRM). A multistep optimisation routine based on genetic algorithm (GA) and MATLAB/SIMPACK co-simulation is executed at three levels. The bogie conventional secondary and primary suspension components are chosen as the design parameters in the first two steps, respectively. In the last step semi-active suspension is in focus. The input electrical current to magnetorheological yaw dampers is optimised to guarantee an appropriate safety level. Semi-active controllers are also applied and the respective effects on bogie dynamics are explored. The safety Pareto optimised results are compared with those associated with in-service values. The global sensitivity analysis and multistep approach significantly reduced the number of design parameters and improved the computational efficiency of the optimisation. Furthermore, using the optimised values of design parameters give the possibility to run the vehicle up to 13% faster on curves while a satisfactory safety level is guaranteed. The results obtained can be used in Pareto optimisation and active bogie suspension design problems.

  17. The effects of mild germinal matrix-intraventricular haemorrhage on the developmental white matter microstructure of preterm neonates. A DTI study

    International Nuclear Information System (INIS)

    Tortora, Domenico; Martinetti, Carola; Severino, Mariasavina; Morana, Giovanni; Rossi, Andrea; Uccella, Sara; Brera, Fabia; Malova, Mariya; Parodi, Alessandro; Ramenghi, Luca Antonio

    2018-01-01

    To evaluate white matter (WM) microstructural changes in preterm neonates (PN) with mild germinal matrix-intraventricular haemorrhage (mGMH-IVH) (grades I and II) and no other associated MRI abnormalities, and correlate them with gestational age (GA) and neurodevelopmental outcome. Tract-based spatial-statistics (TBSS) was performed on DTI of 103 patients studied at term-equivalent age, to compare diffusional parameters (fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), axial diffusivity (AD)) between mGMH-IVH neonates (24/103) and controls matched by GA at birth and sex. The relationship between DTI abnormalities, GA and neurodevelopmental outcome assessed with Griffiths' Developmental Scale-Revised:0-2 was explored using TBSS and Spearman-correlation analysis (p <.05). Affected neonates had lower FA, higher RD and MD of the corpus callosum, limbic pathways and cerebellar tracts. Extremely preterm neonates (GA < 29 weeks) presented more severe microstructural impairment (higher RD and MD) in periventricular regions. Neonates of GA ≥ 29 weeks had milder WM alterations (lower FA), also in subcortical WM. DTI abnormalities were associated with poorer locomotor, eye-hand coordination and performance outcomes at 24 months. WM microstructural changes occur in PN with mGMH-IVH with a GA-dependent selective vulnerability of WM regions, and correlate with adverse neurodevelopmental outcome at 24 months. (orig.)

  18. The effects of mild germinal matrix-intraventricular haemorrhage on the developmental white matter microstructure of preterm neonates. A DTI study

    Energy Technology Data Exchange (ETDEWEB)

    Tortora, Domenico; Martinetti, Carola; Severino, Mariasavina; Morana, Giovanni; Rossi, Andrea [Istituto Giannina Gaslini, Neuroradiology Unit, Genoa (Italy); Uccella, Sara; Brera, Fabia [Istituto Giannina Gaslini, Neuropsychiatry Unit, Genoa (Italy); Malova, Mariya; Parodi, Alessandro; Ramenghi, Luca Antonio [Istituto Giannina Gaslini, Neonatal Intensive Care Unit, Genoa (Italy)

    2018-03-15

    To evaluate white matter (WM) microstructural changes in preterm neonates (PN) with mild germinal matrix-intraventricular haemorrhage (mGMH-IVH) (grades I and II) and no other associated MRI abnormalities, and correlate them with gestational age (GA) and neurodevelopmental outcome. Tract-based spatial-statistics (TBSS) was performed on DTI of 103 patients studied at term-equivalent age, to compare diffusional parameters (fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), axial diffusivity (AD)) between mGMH-IVH neonates (24/103) and controls matched by GA at birth and sex. The relationship between DTI abnormalities, GA and neurodevelopmental outcome assessed with Griffiths' Developmental Scale-Revised:0-2 was explored using TBSS and Spearman-correlation analysis (p <.05). Affected neonates had lower FA, higher RD and MD of the corpus callosum, limbic pathways and cerebellar tracts. Extremely preterm neonates (GA < 29 weeks) presented more severe microstructural impairment (higher RD and MD) in periventricular regions. Neonates of GA ≥ 29 weeks had milder WM alterations (lower FA), also in subcortical WM. DTI abnormalities were associated with poorer locomotor, eye-hand coordination and performance outcomes at 24 months. WM microstructural changes occur in PN with mGMH-IVH with a GA-dependent selective vulnerability of WM regions, and correlate with adverse neurodevelopmental outcome at 24 months. (orig.)

  19. Microstructural integrity of white matter tracts amongst older fallers: A DTI study.

    Directory of Open Access Journals (Sweden)

    Yoke Queen Wong

    Full Text Available This study assesses the whole brain microstructural integrity of white matter tracts (WMT among older individuals with a history of falls compared to non-fallers.85 participants (43 fallers, 42 non-fallers were evaluated with conventional MRI and diffusion tensor imaging (DTI sequences of the brain. DTI metrics were obtained from selected WMT using tract-based spatial statistics (TBSS method. This was followed by binary logistic regression to investigate the clinical variables that could act as confounding elements on the outcomes. The TBSS analysis was then repeated, but this time including all significant predictor variables from the regression analysis as TBSS covariates.The mean diffusivity (MD and axial diffusivity (AD and to a lesser extent radial diffusivity (RD values of the projection fibers and commissural bundles were significantly different in fallers (p < 0.05 compared to non-fallers. However, the final logistic regression model obtained showed that only functional reach, white matter lesion volume, hypertension and orthostatic hypotension demonstrated statistical significant differences between fallers and non-fallers. No significant differences were found in the DTI metrics when taking into account age and the four variables as covariates in the repeated analysis.This DTI study of 85 subjects, do not support DTI metrics as a singular factor that contributes independently to the fall outcomes. Other clinical and imaging factors have to be taken into account.

  20. Beam position optimisation for IMRT

    International Nuclear Information System (INIS)

    Holloway, L.; Hoban, P.

    2001-01-01

    Full text: The introduction of IMRT has not generally resulted in the use of optimised beam positions because to find the global solution of the problem a time consuming stochastic optimisation method must be used. Although a deterministic method may not achieve the global minimum it should achieve a superior dose distribution compared to no optimisation. This study aimed to develop and test such a method. The beam optimisation method developed relies on an iterative process to achieve the desired number of beams from a large initial number of beams. The number of beams is reduced in a 'weeding-out' process based on the total fluence which each beam delivers. The process is gradual, with only three beams removed each time (following a small number of iterations), ensuring that the reduction in beams does not dramatically affect the fluence maps of those remaining. A comparison was made between the dose distributions achieved when the beams positions were optimised in this fashion and when the beams positions were evenly distributed. The method has been shown to work quite effectively and efficiently. The Figure shows a comparison in dose distribution with optimised and non optimised beam positions for 5 beams. It can be clearly seen that there is an improvement in the dose distribution delivered to the tumour and a reduction in the dose to the critical structure with beam position optimisation. A method for beam position optimisation for use in IMRT optimisations has been developed. This method although not necessarily achieving the global minimum in beam position still achieves quite a dramatic improvement compared with no beam position optimisation and is very efficiently achieved. Copyright (2001) Australasian College of Physical Scientists and Engineers in Medicine

  1. The Carbon Trust and DTI Renewables network impacts study

    Energy Technology Data Exchange (ETDEWEB)

    MacDonald, Mott

    2005-11-15

    The study's key objectives, as set by the Renewables Advisory Board, the Carbon Trust and DTI, are as follows: To undertake a forward renewables capacity mapping exercise derived from the generation companies' investment plans to 2010, and if the capacity mapping exercise indicates that the planned level of activity is unlikely to meet the 2010 target, to devise and consider a small number of scenarios whereby the 10% target could be achieved; To determine how the transmission and distribution networks need to evolve to enable the Government's 2010 target of 10% of electricity supplied from renewable sources and the aspiration to double that percentage; To investigate the network issues regarding the intermittent nature of renewable generation and the characterisation of renewable generation with regard to grid code compliance; To provide insights into the actions and the stepping stones required between now and 2020 for the key decisions and investments relating to the transformation of the transmission and distribution network, and those issues likely to affect the rate of progress toward the targets. The study also analyses whether there are potential network impacts on renewables expansion from a simultaneous expansion of the UK's CHP capacity to meet the Government target of 10GW of CHP by 2010. The study (which was largely completed ahead of the Government's announcement on extension of the Renewables Obligation Order to 2015, and the raising of the renewables target to 15% of electricity sales by 2015) has found that based on business plans, developers can meet about 72% of the 2010 target by 20061. The Government's announcement has been welcomed by the renewables community and is expected to give added confidence to developers and investors that the Government is intent on creating a long term stable regime to incentivise investment in renewable energy technologies. However, in parallel with tackling what was a decline in

  2. Parameter Estimation

    DEFF Research Database (Denmark)

    Sales-Cruz, Mauricio; Heitzig, Martina; Cameron, Ian

    2011-01-01

    of optimisation techniques coupled with dynamic solution of the underlying model. Linear and nonlinear approaches to parameter estimation are investigated. There is also the application of maximum likelihood principles in the estimation of parameters, as well as the use of orthogonal collocation to generate a set......In this chapter the importance of parameter estimation in model development is illustrated through various applications related to reaction systems. In particular, rate constants in a reaction system are obtained through parameter estimation methods. These approaches often require the application...... of algebraic equations as the basis for parameter estimation.These approaches are illustrated using estimations of kinetic constants from reaction system models....

  3. ATLAS software configuration and build tool optimisation

    Science.gov (United States)

    Rybkin, Grigory; Atlas Collaboration

    2014-06-01

    ATLAS software code base is over 6 million lines organised in about 2000 packages. It makes use of some 100 external software packages, is developed by more than 400 developers and used by more than 2500 physicists from over 200 universities and laboratories in 6 continents. To meet the challenge of configuration and building of this software, the Configuration Management Tool (CMT) is used. CMT expects each package to describe its build targets, build and environment setup parameters, dependencies on other packages in a text file called requirements, and each project (group of packages) to describe its policies and dependencies on other projects in a text project file. Based on the effective set of configuration parameters read from the requirements files of dependent packages and project files, CMT commands build the packages, generate the environment for their use, or query the packages. The main focus was on build time performance that was optimised within several approaches: reduction of the number of reads of requirements files that are now read once per package by a CMT build command that generates cached requirements files for subsequent CMT build commands; introduction of more fine-grained build parallelism at package task level, i.e., dependent applications and libraries are compiled in parallel; code optimisation of CMT commands used for build; introduction of package level build parallelism, i. e., parallelise the build of independent packages. By default, CMT launches NUMBER-OF-PROCESSORS build commands in parallel. The other focus was on CMT commands optimisation in general that made them approximately 2 times faster. CMT can generate a cached requirements file for the environment setup command, which is especially useful for deployment on distributed file systems like AFS or CERN VMFS. The use of parallelism, caching and code optimisation significantly-by several times-reduced software build time, environment setup time, increased the efficiency of

  4. Optimisation of occupational exposure

    International Nuclear Information System (INIS)

    Webb, G.A.M.; Fleishman, A.B.

    1982-01-01

    The general concept of the optimisation of protection of the public is briefly described. Some ideas being developed for extending the cost benefit framework to include radiation workers with full implementation of the ALARA criterion are described. The role of cost benefit analysis in radiological protection and the valuation of health detriment including the derivation of monetary values and practical implications are discussed. Cost benefit analysis can lay out for inspection the doses, the associated health detriment costs and the costs of protection for alternative courses of action. However it is emphasised that the cost benefit process is an input to decisions on what is 'as low as reasonably achievable' and not a prescription for making them. (U.K.)

  5. Standardised approach to optimisation

    International Nuclear Information System (INIS)

    Warren-Forward, Helen M.; Beckhaus, Ronald

    2004-01-01

    Optimisation of radiographic images is said to have been obtained if the patient has achieved an acceptable level of dose and the image is of diagnostic value. In the near future, it will probably be recommended that radiographers measure patient doses and compare them to reference levels. The aim of this paper is to describe a standardised approach to optimisation of radiographic examinations in a diagnostic imaging department. A three-step approach is outlined with specific examples for some common examinations (chest, abdomen, pelvis and lumbar spine series). Step One: Patient doses are calculated. Step Two: Doses are compared to existing reference levels and the technique used compared to image quality criteria. Step Three: Appropriate action is taken if doses are above the reference level. Results: Average entrance surface doses for two rooms were as follows AP Abdomen (6.3mGy and 3.4mGy); AP Lumbar Spine (6.4mGy and 4.1mGy) for AP Pelvis (4.8mGy and 2.6mGy) and PA chest (0.19mGy and 0.20mGy). Comparison with the Commission of the European Communities (CEC) recommended techniques identified large differences in the applied potential. The kVp values in this study were significantly lower (by up to lOkVp) than the CEC recommendations. The results of this study have indicated that there is a need to monitor radiation doses received by patients undergoing diagnostic radiography examinations. Not only has the assessment allowed valuable comparison with International Diagnostic Reference Levels and Radiography Good Practice but has demonstrated large variations in mean doses being delivered from different rooms of the same radiology department. Following the simple 3-step approach advocated in this paper should either provide evidence that department are practising the ALARA principle or assist in making suitable changes to current practice. Copyright (2004) Australian Institute of Radiography

  6. Population-averaged macaque brain atlas with high-resolution ex vivo DTI integrated into in vivo space.

    Science.gov (United States)

    Feng, Lei; Jeon, Tina; Yu, Qiaowen; Ouyang, Minhui; Peng, Qinmu; Mishra, Virendra; Pletikos, Mihovil; Sestan, Nenad; Miller, Michael I; Mori, Susumu; Hsiao, Steven; Liu, Shuwei; Huang, Hao

    2017-12-01

    Animal models of the rhesus macaque (Macaca mulatta), the most widely used nonhuman primate, have been irreplaceable in neurobiological studies. However, a population-averaged macaque brain diffusion tensor imaging (DTI) atlas, including comprehensive gray and white matter labeling as well as bony and facial landmarks guiding invasive experimental procedures, is not available. The macaque white matter tract pathways and microstructures have been rarely recorded. Here, we established a population-averaged macaque brain atlas with high-resolution ex vivo DTI integrated into in vivo space incorporating bony and facial landmarks, and delineated microstructures and three-dimensional pathways of major white matter tracts in vivo MRI/DTI and ex vivo (postmortem) DTI of ten rhesus macaque brains were acquired. Single-subject macaque brain DTI template was obtained by transforming the postmortem high-resolution DTI data into in vivo space. Ex vivo DTI of ten macaque brains was then averaged in the in vivo single-subject template space to generate population-averaged macaque brain DTI atlas. The white matter tracts were traced with DTI-based tractography. One hundred and eighteen neural structures including all cortical gyri, white matter tracts and subcortical nuclei, were labeled manually on population-averaged DTI-derived maps. The in vivo microstructural metrics of fractional anisotropy, axial, radial and mean diffusivity of the traced white matter tracts were measured. Population-averaged digital atlas integrated into in vivo space can be used to label the experimental macaque brain automatically. Bony and facial landmarks will be available for guiding invasive procedures. The DTI metric measurements offer unique insights into heterogeneous microstructural profiles of different white matter tracts.

  7. A novel DTI-QA tool: Automated metric extraction exploiting the sphericity of an agar filled phantom.

    Science.gov (United States)

    Chavez, Sofia; Viviano, Joseph; Zamyadi, Mojdeh; Kingsley, Peter B; Kochunov, Peter; Strother, Stephen; Voineskos, Aristotle

    2018-02-01

    To develop a quality assurance (QA) tool (acquisition guidelines and automated processing) for diffusion tensor imaging (DTI) data using a common agar-based phantom used for fMRI QA. The goal is to produce a comprehensive set of automated, sensitive and robust QA metrics. A readily available agar phantom was scanned with and without parallel imaging reconstruction. Other scanning parameters were matched to the human scans. A central slab made up of either a thick slice or an average of a few slices, was extracted and all processing was performed on that image. The proposed QA relies on the creation of two ROIs for processing: (i) a preset central circular region of interest (ccROI) and (ii) a signal mask for all images in the dataset. The ccROI enables computation of average signal for SNR calculations as well as average FA values. The production of the signal masks enables automated measurements of eddy current and B0 inhomogeneity induced distortions by exploiting the sphericity of the phantom. Also, the signal masks allow automated background localization to assess levels of Nyquist ghosting. The proposed DTI-QA was shown to produce eleven metrics which are robust yet sensitive to image quality changes within site and differences across sites. It can be performed in a reasonable amount of scan time (~15min) and the code for automated processing has been made publicly available. A novel DTI-QA tool has been proposed. It has been applied successfully on data from several scanners/platforms. The novelty lies in the exploitation of the sphericity of the phantom for distortion measurements. Other novel contributions are: the computation of an SNR value per gradient direction for the diffusion weighted images (DWIs) and an SNR value per non-DWI, an automated background detection for the Nyquist ghosting measurement and an error metric reflecting the contribution of EPI instability to the eddy current induced shape changes observed for DWIs. Copyright © 2017 Elsevier

  8. Topology optimised wavelength dependent splitters

    DEFF Research Database (Denmark)

    Hede, K. K.; Burgos Leon, J.; Frandsen, Lars Hagedorn

    A photonic crystal wavelength dependent splitter has been constructed by utilising topology optimisation1. The splitter has been fabricated in a silicon-on-insulator material (Fig. 1). The topology optimised wavelength dependent splitter demonstrates promising 3D FDTD simulation results....... This complex photonic crystal structure is very sensitive against small fabrication variations from the expected topology optimised design. A wavelength dependent splitter is an important basic building block for high-performance nanophotonic circuits. 1J. S. Jensen and O. Sigmund, App. Phys. Lett. 84, 2022...

  9. Interhemispheric Functional and Structural Disconnection in Alzheimer's Disease: A Combined Resting-State fMRI and DTI Study.

    Directory of Open Access Journals (Sweden)

    Zhiqun Wang

    Full Text Available Neuroimaging studies have demonstrated that patients with Alzheimer's disease presented disconnection syndrome. However, little is known about the alterations of interhemispheric functional interactions and underlying structural connectivity in the AD patients. In this study, we combined resting-state functional MRI and diffusion tensor imaging (DTI to investigate interhemispheric functional and structural connectivity in 16 AD, 16 mild cognitive impairment (MCI, as well as 16 cognitive normal healthy subjects (CN. The pattern of the resting state interhemispheric functional connectivity was measured with a voxel-mirrored homotopic connectivity (VMHC method. Decreased VMHC was observed in AD and MCI subjects in anterior brain regions including the prefrontal cortices and subcortical regions with a pattern of ADDTI analysis showed the most significant difference among the three cohorts was the fractional anisotropy in the genu of corpus callosum, which was positively associated with the VMHC of prefrontal and subcortical regions. Across all the three cohorts, the diffusion parameters in the genu of corpus callosum and VMHC in the above brain regions had significant correlation with the cognitive performance. These results demonstrate that there are specific patterns of interhemispheric functional connectivity changes in the AD and MCI, which can be significantly correlated with the integrity changes in the midline white matter structures. These results suggest that VMHC can be used as a biomarker for the degeneration of the interhemispheric connectivity in AD.

  10. Feasibility of diffusion tensor imaging (DTI) with fibre tractography of the normal female pelvic floor

    International Nuclear Information System (INIS)

    Zijta, F.M.; Froeling, M.; Paardt, M.P. van der; Bipat, S.; Nederveen, A.J.; Stoker, J.; Lakeman, M.M.E.; Montauban van Swijndregt, A.D.; Strijkers, G.J.

    2011-01-01

    To prospectively determine the feasibility of diffusion tensor imaging (DTI) with fibre tractography as a tool for the three-dimensional (3D) visualisation of normal pelvic floor anatomy. Five young female nulliparous subjects (mean age 28 ± 3 years) underwent DTI at 3.0T. Two-dimensional diffusion-weighted axial spin-echo echo-planar (SP-EPI) pulse sequence of the pelvic floor was performed, with additional T2-TSE multiplanar sequences for anatomical reference. Fibre tractography for visualisation of predefined pelvic floor and pelvic wall muscles was performed offline by two observers, applying a consensus method. Three eigenvalues (λ1, λ2, λ3), fractional anisotropy (FA) and mean diffusivity (MD) were calculated from the fibre trajectories. In all subjects fibre tractography resulted in a satisfactory anatomical representation of the pubovisceral muscle, perineal body, anal - and urethral sphincter complex and internal obturator muscle. Mean FA values ranged from 0.23 ± 0.02 to 0.30 ± 0.04, MD values from 1.30 ± 0.08 to 1.73 ± 0.12 x 10- 3 mm 2 /s. Muscular structures in the superficial layer of the pelvic floor could not be satisfactorily identified. This study demonstrates the feasibility of visualising the complex three-dimensional pelvic floor architecture using 3T-DTI with fibre tractography. DTI of the deep female pelvic floor may provide new insights into pelvic floor disorders. (orig.)

  11. Acute radial nerve entrapment at the spiral groove: detection by DTI-based neurography

    Energy Technology Data Exchange (ETDEWEB)

    Jengojan, Suren; Breitenseher, Julia; Weber, Michael; Prayer, Daniela; Kasprian, Gregor [Medical University of Vienna, Department of Biomedical Imaging and Image-guided Therapy, Division of Neuro- and Musculosceletal Radiology, Vienna (Austria); Kovar, Florian [Medical University of Vienna, Department of Trauma-Surgery, Vienna (Austria)

    2015-06-01

    This study evaluated the potential of three-tesla diffusion tensor imaging (DTI) and tractography to detect changes of the radial (RN) and median (MN) nerves during transient upper arm compression by a silicon ring tourniquet. Axial T2-weighted and DTI sequences (b = 700 s/mm{sup 2}, 16 gradient encoding directions) of 13 healthy volunteers were obtained. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of the MN and RN were measured at the spiral groove and further visualized in 3D by deterministic tractography (thresholds: FA =.15, angle change = 27 ). Local/lesional RN FA values increased (p = 0.001) and ADC values decreased (p = 0.02) during a 20-min upper arm compression, whereas no significant FA (p = 0.49) or ADC (p = 0.73) changes of the MN were detected. There were no T2-w nerve signal changes or alterations of nerve trajectories in 3D. Acute nerve compression of the RN leads to changes of its three-tesla DTI metrics. Peripheral nerve DTI provides non-invasive insights into the ''selective'' vulnerability of the RN at the spiral groove. (orig.)

  12. Feasibility of diffusion tensor imaging (DTI) with fibre tractography of the normal female pelvic floor

    Energy Technology Data Exchange (ETDEWEB)

    Zijta, F.M. [University of Amsterdam, Department of Radiology, Academic Medical Center, Amsterdam (Netherlands); Onze Lieve Vrouwe Gasthuis, Department of Radiology, Amsterdam (Netherlands); Froeling, M. [University of Amsterdam, Department of Radiology, Academic Medical Center, Amsterdam (Netherlands); Eindhoven University of Technology, Biomedical NMR, Department of Biomedical Engineering, Eindhoven (Netherlands); Paardt, M.P. van der; Bipat, S.; Nederveen, A.J.; Stoker, J. [University of Amsterdam, Department of Radiology, Academic Medical Center, Amsterdam (Netherlands); Lakeman, M.M.E. [University of Amsterdam, Department of Gynaecology, Academic Medical Center, Amsterdam (Netherlands); Montauban van Swijndregt, A.D. [Onze Lieve Vrouwe Gasthuis, Department of Radiology, Amsterdam (Netherlands); Strijkers, G.J. [Eindhoven University of Technology, Biomedical NMR, Department of Biomedical Engineering, Eindhoven (Netherlands)

    2011-06-15

    To prospectively determine the feasibility of diffusion tensor imaging (DTI) with fibre tractography as a tool for the three-dimensional (3D) visualisation of normal pelvic floor anatomy. Five young female nulliparous subjects (mean age 28 {+-} 3 years) underwent DTI at 3.0T. Two-dimensional diffusion-weighted axial spin-echo echo-planar (SP-EPI) pulse sequence of the pelvic floor was performed, with additional T2-TSE multiplanar sequences for anatomical reference. Fibre tractography for visualisation of predefined pelvic floor and pelvic wall muscles was performed offline by two observers, applying a consensus method. Three eigenvalues ({lambda}1, {lambda}2, {lambda}3), fractional anisotropy (FA) and mean diffusivity (MD) were calculated from the fibre trajectories. In all subjects fibre tractography resulted in a satisfactory anatomical representation of the pubovisceral muscle, perineal body, anal - and urethral sphincter complex and internal obturator muscle. Mean FA values ranged from 0.23 {+-} 0.02 to 0.30 {+-} 0.04, MD values from 1.30 {+-} 0.08 to 1.73 {+-} 0.12 x 10-{sup 3} mm{sup 2}/s. Muscular structures in the superficial layer of the pelvic floor could not be satisfactorily identified. This study demonstrates the feasibility of visualising the complex three-dimensional pelvic floor architecture using 3T-DTI with fibre tractography. DTI of the deep female pelvic floor may provide new insights into pelvic floor disorders. (orig.)

  13. The optimisation study of tbp synthesis process by phosphoric acid

    International Nuclear Information System (INIS)

    Amedjkouh, A.; Attou, M.; Azzouz, A.; Zaoui, B.

    1995-07-01

    The present work deals with the optimisation study of TBP synthesis process by phosphoric acid. This way of synthesis is more advantageous than POCL3 or P2O5 as phosphatant agents. these latters are toxic and dangerous for the environnement. The optimisation study is based on a series of 16 experiences taking into account the range of variation of the following parameters : temperature, pressure, reagents mole ratio, promoter content. the yield calculation is based on the randomisation of an equation including all parameters. the resolution of this equation gave a 30% TBP molar ratio. this value is in agreement with that of experimental data

  14. Optimisation of the Laser Cutting Process

    DEFF Research Database (Denmark)

    Dragsted, Birgitte; Olsen, Flemmming Ove

    1996-01-01

    The problem in optimising the laser cutting process is outlined. Basic optimisation criteria and principles for adapting an optimisation method, the simplex method, are presented. The results of implementing a response function in the optimisation are discussed with respect to the quality as well...

  15. Turbulence optimisation in stellarator experiments

    Energy Technology Data Exchange (ETDEWEB)

    Proll, Josefine H.E. [Max-Planck/Princeton Center for Plasma Physics (Germany); Max-Planck-Institut fuer Plasmaphysik, Wendelsteinstr. 1, 17491 Greifswald (Germany); Faber, Benjamin J. [HSX Plasma Laboratory, University of Wisconsin-Madison, Madison, WI 53706 (United States); Helander, Per; Xanthopoulos, Pavlos [Max-Planck/Princeton Center for Plasma Physics (Germany); Lazerson, Samuel A.; Mynick, Harry E. [Plasma Physics Laboratory, Princeton University, P.O. Box 451 Princeton, New Jersey 08543-0451 (United States)

    2015-05-01

    Stellarators, the twisted siblings of the axisymmetric fusion experiments called tokamaks, have historically suffered from confining the heat of the plasma insufficiently compared with tokamaks and were therefore considered to be less promising candidates for a fusion reactor. This has changed, however, with the advent of stellarators in which the laminar transport is reduced to levels below that of tokamaks by shaping the magnetic field accordingly. As in tokamaks, the turbulent transport remains as the now dominant transport channel. Recent analytical theory suggests that the large configuration space of stellarators allows for an additional optimisation of the magnetic field to also reduce the turbulent transport. In this talk, the idea behind the turbulence optimisation is explained. We also present how an optimised equilibrium is obtained and how it might differ from the equilibrium field of an already existing device, and we compare experimental turbulence measurements in different configurations of the HSX stellarator in order to test the optimisation procedure.

  16. Optimisation of load control

    International Nuclear Information System (INIS)

    Koponen, P.

    1998-01-01

    Electricity cannot be stored in large quantities. That is why the electricity supply and consumption are always almost equal in large power supply systems. If this balance were disturbed beyond stability, the system or a part of it would collapse until a new stable equilibrium is reached. The balance between supply and consumption is mainly maintained by controlling the power production, but also the electricity consumption or, in other words, the load is controlled. Controlling the load of the power supply system is important, if easily controllable power production capacity is limited. Temporary shortage of capacity causes high peaks in the energy price in the electricity market. Load control either reduces the electricity consumption during peak consumption and peak price or moves electricity consumption to some other time. The project Optimisation of Load Control is a part of the EDISON research program for distribution automation. The following areas were studied: Optimization of space heating and ventilation, when electricity price is time variable, load control model in power purchase optimization, optimization of direct load control sequences, interaction between load control optimization and power purchase optimization, literature on load control, optimization methods and field tests and response models of direct load control and the effects of the electricity market deregulation on load control. An overview of the main results is given in this chapter

  17. Optimisation of load control

    Energy Technology Data Exchange (ETDEWEB)

    Koponen, P [VTT Energy, Espoo (Finland)

    1998-08-01

    Electricity cannot be stored in large quantities. That is why the electricity supply and consumption are always almost equal in large power supply systems. If this balance were disturbed beyond stability, the system or a part of it would collapse until a new stable equilibrium is reached. The balance between supply and consumption is mainly maintained by controlling the power production, but also the electricity consumption or, in other words, the load is controlled. Controlling the load of the power supply system is important, if easily controllable power production capacity is limited. Temporary shortage of capacity causes high peaks in the energy price in the electricity market. Load control either reduces the electricity consumption during peak consumption and peak price or moves electricity consumption to some other time. The project Optimisation of Load Control is a part of the EDISON research program for distribution automation. The following areas were studied: Optimization of space heating and ventilation, when electricity price is time variable, load control model in power purchase optimization, optimization of direct load control sequences, interaction between load control optimization and power purchase optimization, literature on load control, optimization methods and field tests and response models of direct load control and the effects of the electricity market deregulation on load control. An overview of the main results is given in this chapter

  18. SPS batch spacing optimisation

    CERN Document Server

    Velotti, F M; Carlier, E; Goddard, B; Kain, V; Kotzian, G

    2017-01-01

    Until 2015, the LHC filling schemes used the batch spac-ing as specified in the LHC design report. The maximumnumber of bunches injectable in the LHC directly dependson the batch spacing at injection in the SPS and hence onthe MKP rise time.As part of the LHC Injectors Upgrade project for LHCheavy ions, a reduction of the batch spacing is needed. In thisdirection, studies to approach the MKP design rise time of150ns(2-98%) have been carried out. These measurementsgave clear indications that such optimisation, and beyond,could be done also for higher injection momentum beams,where the additional slower MKP (MKP-L) is needed.After the successful results from 2015 SPS batch spacingoptimisation for the Pb-Pb run [1], the same concept wasthought to be used also for proton beams. In fact, thanksto the SPS transverse feed back, it was already observedthat lower batch spacing than the design one (225ns) couldbe achieved. For the 2016 p-Pb run, a batch spacing of200nsfor the proton beam with100nsbunch spacing wasreque...

  19. Optimisation of the PCR-invA primers for the detection of Salmonella ...

    African Journals Online (AJOL)

    A polymerase chain reaction (PCR)-based method for the detection of Salmonella species in water samples was optimised and evaluated for speed, specificity and sensitivity. Optimisation of Mg2+ and primer concentrations and cycling parameters increased the sensitivity and limit of detection of PCR to 2.6 x 104 cfu/m.

  20. Vaccine strategies: Optimising outcomes.

    Science.gov (United States)

    Hardt, Karin; Bonanni, Paolo; King, Susan; Santos, Jose Ignacio; El-Hodhod, Mostafa; Zimet, Gregory D; Preiss, Scott

    2016-12-20

    factors that encourage success, which often include strong support from government and healthcare organisations, as well as tailored, culturally-appropriate local approaches to optimise outcomes. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  1. A conceptual optimisation strategy for radiography in a digital environment

    International Nuclear Information System (INIS)

    Baath, M.; Haakansson, M.; Hansson, J.; Maansson, L. G.

    2005-01-01

    Using a completely digital environment for the entire imaging process leads to new possibilities for optimisation of radiography since many restrictions of screen/film systems, such as the small dynamic range and the lack of possibilities for image processing, do not apply any longer. However, at the same time these new possibilities lead to a more complicated optimisation process, since more freedom is given to alter parameters. This paper focuses on describing an optimisation strategy that concentrates on taking advantage of the conceptual differences between digital systems and screen/film systems. The strategy can be summarised as: (a) always include the anatomical background during the optimisation, (b) perform all comparisons at a constant effective dose and (c) separate the image display stage from the image collection stage. A three-step process is proposed where the optimal setting of the technique parameters is determined at first, followed by an optimisation of the image processing. In the final step the optimal dose level - given the optimal settings of the image collection and image display stages - is determined. (authors)

  2. Correlations between Diffusion Tensor Imaging (DTI and Magnetic Resonance Spectroscopy (1H MRS in schizophrenic patients and normal controls

    Directory of Open Access Journals (Sweden)

    Ng Johnny

    2007-06-01

    Full Text Available Abstract Background Evidence suggests that white matter integrity may play an underlying pathophysiological role in schizophrenia. N-acetylaspartate (NAA, as measured by Magnetic Resonance Spectroscopy (MRS, is a neuronal marker and is decreased in white matter lesions and regions of axonal loss. It has also been found to be reduced in the prefrontal and temporal regions in patients with schizophrenia. Diffusion Tensor Imaging (DTI allows one to measure the orientations of axonal tracts as well as the coherence of axonal bundles. DTI is thus sensitive to demyelination and other structural abnormalities. DTI has also shown abnormalities in these regions. Methods MRS and DTI were obtained on 42 healthy subjects and 40 subjects with schizophrenia. The data was analyzed using regions of interests in the Dorso-Lateral Prefrontal white matter, Medial Temporal white matter and Occipital white matter using both imaging modalities. Results NAA was significantly reduced in the patient population in the Medial Temporal regions. DTI anisotropy indices were also reduced in the same Medial Temporal regions. NAA and DTI-anisotropy indices were also correlated in the left medial temporal region. Conclusion Our results implicate defects in the medial temporal white matter in patients with schizophrenia. Moreover, MRS and DTI are complementary modalities for the study of white matter disruptions in patients with schizophrenia.

  3. Thermal performance monitoring and optimisation

    International Nuclear Information System (INIS)

    Sunde, Svein; Berg; Oeyvind

    1998-01-01

    Monitoring of the thermal efficiency of nuclear power plants is expected to become increasingly important as energy-market liberalisation exposes plants to increasing availability requirements and fiercer competition. The general goal in thermal performance monitoring is straightforward: to maximise the ratio of profit to cost under the constraints of safe operation. One may perceive this goal to be pursued in two ways, one oriented towards fault detection and cost-optimal predictive maintenance, and another determined at optimising target values of parameters in response to any component degradation detected, changes in ambient conditions, or the like. Annual savings associated with effective thermal-performance monitoring are expected to be in the order of $ 100 000 for power plants of representative size. A literature review shows that a number of computer systems for thermal-performance monitoring exists, either as prototypes or commercially available. The characteristics and needs of power plants may vary widely, however, and decisions concerning the exact scope, content and configuration of a thermal-performance monitor may well follow a heuristic approach. Furthermore, re-use of existing software modules may be desirable. Therefore, we suggest here the design of a flexible workbench for easy assembly of an experimental thermal-performance monitor at the Halden Project. The suggested design draws heavily on our extended experience in implementing control-room systems featured by assets like high levels of customisation, flexibility in configuration and modularity in structure, and on a number of relevant adjoining activities. The design includes a multi-computer communication system and a graphical user's interface, and aims at a system adaptable to any combination of in-house or end user's modules, as well as commercially available software. (author)

  4. Limbic-thalamo-cortical projections and reward-related circuitry integrity affects eating behavior: A longitudinal DTI study in adolescents with restrictive eating disorders.

    Directory of Open Access Journals (Sweden)

    Gaia Olivo

    Full Text Available Few studies have used diffusion tensor imaging (DTI to investigate the micro-structural alterations of WM in patients with restrictive eating disorders (rED, and longitudinal data are lacking. Twelve patients with rED were scanned at diagnosis and after one year of family-based treatment, and compared to twenty-four healthy controls (HCs through DTI analysis. A tract-based spatial statistics procedure was used to investigate diffusivity parameters: fractional anisotropy (FA and mean, radial and axial diffusivities (MD, RD and AD, respectively. Reduced FA and increased RD were found in patients at baseline in the corpus callosum, corona radiata and posterior thalamic radiation compared with controls. However, no differences were found between follow-up patients and controls, suggesting a partial normalization of the diffusivity parameters. In patients, trends for a negative correlation were found between the baseline FA of the right anterior corona radiata and the Eating Disorder Examination Questionnaire total score, while a positive trend was found between the baseline FA in the splenium of corpus callosum and the weight loss occurred between maximal documented weight and time of admission. A positive trend for correlation was also found between baseline FA in the right anterior corona radiata and the decrease in the Obsessive-Compulsive Inventory Revised total score over time. Our results suggest that the integrity of the limbic-thalamo-cortical projections and the reward-related circuitry are important for cognitive control processes and reward responsiveness in regulating eating behavior.

  5. A Potential Biomarker in Amyotrophic Lateral Sclerosis: Can Assessment of Brain Iron Deposition with SWI and Corticospinal Tract Degeneration with DTI Help?

    Science.gov (United States)

    Sheelakumari, R; Madhusoodanan, M; Radhakrishnan, A; Ranjith, G; Thomas, B

    2016-02-01

    Iron-mediated oxidative stress plays a pivotal role in the pathogenesis of amyotrophic lateral sclerosis. This study aimed to assess iron deposition qualitatively and quantitatively by using SWI and microstructural changes in the corticospinal tract by using DTI in patients with amyotrophic lateral sclerosis. Seventeen patients with amyotrophic lateral sclerosis and 15 age- and sex-matched controls underwent brain MR imaging with SWI and DTI. SWI was analyzed for both signal-intensity scoring and quantitative estimation of iron deposition in the anterior and posterior banks of the motor and sensory cortices and deep gray nuclei. The diffusion measurements along the corticospinal tract at the level of pons and medulla were obtained by ROI analysis. Patients with amyotrophic lateral sclerosis showed reduced signal-intensity grades in the posterior bank of the motor cortex bilaterally. Quantitative analysis confirmed significantly higher iron content in the posterior bank of the motor cortex in patients with amyotrophic lateral sclerosis. In contrast, no significant differences were noted for the anterior bank of the motor cortex, anterior and posterior banks of the sensory cortex, and deep nuclei. Receiver operating characteristic comparison showed a cutoff of 35μg Fe/g of tissue with an area under the curve of 0.78 (P = .008) for the posterior bank of the motor cortex in discriminating patients with amyotrophic lateral sclerosis from controls. Fractional anisotropy was lower in the pyramidal tracts of patients with amyotrophic lateral sclerosis at the pons and medulla on either side, along with higher directionally averaged mean diffusivity values. The combination of SWI and DTI revealed an area under the curve of 0.784 for differentiating patients with amyotrophic lateral sclerosis from controls. Measurements of motor cortex iron deposition and diffusion tensor parameters of the corticospinal tract may be useful biomarkers for the diagnosis of clinically suspected

  6. Design of optimised backstepping controller for the synchronisation

    Indian Academy of Sciences (India)

    In this paper, an adaptive backstepping controller has been tuned to synchronise two chaotic Colpitts oscillators in a master–slave configuration. The parameters of the controller are determined using shark smell optimisation (SSO) algorithm. Numerical results are presented and compared with those of particle swarm ...

  7. Multi-Optimisation Consensus Clustering

    Science.gov (United States)

    Li, Jian; Swift, Stephen; Liu, Xiaohui

    Ensemble Clustering has been developed to provide an alternative way of obtaining more stable and accurate clustering results. It aims to avoid the biases of individual clustering algorithms. However, it is still a challenge to develop an efficient and robust method for Ensemble Clustering. Based on an existing ensemble clustering method, Consensus Clustering (CC), this paper introduces an advanced Consensus Clustering algorithm called Multi-Optimisation Consensus Clustering (MOCC), which utilises an optimised Agreement Separation criterion and a Multi-Optimisation framework to improve the performance of CC. Fifteen different data sets are used for evaluating the performance of MOCC. The results reveal that MOCC can generate more accurate clustering results than the original CC algorithm.

  8. Numerical optimisation of friction stir welding: review of future challenges

    DEFF Research Database (Denmark)

    Tutum, Cem Celal; Hattel, Jesper Henri

    2011-01-01

    During the last decade, the combination of increasingly more advanced numerical simulation software with high computational power has resulted in models for friction stir welding (FSW), which have improved the understanding of the determining physical phenomena behind the process substantially....... This has made optimisation of certain process parameters possible and has in turn led to better performing friction stir welded products, thus contributing to a general increase in the popularity of the process and its applications. However, most of these optimisation studies do not go well beyond manual...

  9. Development and optimisation of process parameters for recovery of uranium from calcia slag and lining material (SLM) by leaching process and subsequent recovery of uranium from the leach liquor generated

    International Nuclear Information System (INIS)

    Verma, Dinesh Kumar; Srivastava, Praveen Kumar; Das, Santanu; Kumar, Raj; Roy, S.B.

    2014-01-01

    Presently uranium value is recovered by nitric acid dissolution of the SLM, to get uranyl nitrate solution (UNS) and subsequent solvent extraction process. UNS generated After SLM dissolution is very lean in uranium content and create difficulty in solvent extraction. Moreover, NO X is also generated during SLM dissolution in nitric acid. An alternate process was developed where nitric acid is not being used and uranium is being recovered by leaching out the SLM using acetic acid. The process was also optimised for recovery and overall economics of the process by using process effluent AALL (Acetic Acid Leach Liquor) as a leaching agent. The uranium value in the leach liquor was precipitated by using sodium hydroxide. The precipitate was dissolved in nitric acid and the Uranyl Nitrate Solution generated was having Uranium concentration of 15-30 g/l. The alternate process developed will have less effluent generation, less NO X generation and will produce more concentrated UNS in comparison to the nitric acid dissolution process

  10. Brain structure in narcissistic personality disorder: a VBM and DTI pilot study.

    Science.gov (United States)

    Nenadic, Igor; Güllmar, Daniel; Dietzek, Maren; Langbein, Kerstin; Steinke, Johanna; Gaser, Christian

    2015-02-28

    We analysed T1-weighted MRI scans using voxel-based morphometry (VBM) and tract-based spatial statistics (TBBS) on diffusion tensor images (DTI) in narcissistic personality disorder (NaPD) patients and healthy controls. Grey matter deficits include right prefrontal and bilateral medial prefrontal/anterior cingulate cortices, and decreased fractional anisotropy in right frontal lobe white matter. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  11. Isogeometric Analysis and Shape Optimisation

    DEFF Research Database (Denmark)

    Gravesen, Jens; Evgrafov, Anton; Gersborg, Allan Roulund

    of the whole domain. So in every optimisation cycle we need to extend a parametrisation of the boundary of a domain to the whole domain. It has to be fast in order not to slow the optimisation down but it also has to be robust and give a parametrisation of high quality. These are conflicting requirements so we...... will explain how the validity of a parametrisation can be checked and we will describe various ways to parametrise a domain. We will in particular study the Winslow functional which turns out to have some desirable properties. Other problems we touch upon is clustering of boundary control points (design...

  12. UNC-Utah NA-MIC Framework for DTI Fiber Tract Analysis

    Directory of Open Access Journals (Sweden)

    Audrey Rose Verde

    2014-01-01

    Full Text Available Diffusion tensor imaging has become an important modality in the field ofneuroimaging to capture changes in micro-organization and to assess white matterintegrity or development. While there exists a number of tractography toolsets,these usually lack tools for preprocessing or to analyze diffusion properties alongthe fiber tracts. Currently, the field is in critical need of a coherent end-to-endtoolset for performing an along-fiber tract analysis, accessible to non-technicalneuroimaging researchers. The UNC-Utah NA-MIC DTI framework represents acoherent, open source, end-to-end toolset for atlas fiber tract based DTI analysisencompassing DICOM data conversion, quality control, atlas building, fibertractography, fiber parameterization, and statistical analysis of diffusionproperties. Most steps utilize graphical user interfaces (GUI to simplifyinteraction and provide an extensive DTI analysis framework for non-technicalresearchers/investigators. We illustrate the use of our framework on a smallsample, cross sectional neuroimaging study of 8 healthy 1-year-old children fromthe Infant Brain Imaging Study (IBIS Network. In this limited test study, weillustrate the power of our method by quantifying the diffusion properties at 1year of age on the genu and splenium fiber tracts.

  13. UNC-Utah NA-MIC framework for DTI fiber tract analysis.

    Science.gov (United States)

    Verde, Audrey R; Budin, Francois; Berger, Jean-Baptiste; Gupta, Aditya; Farzinfar, Mahshid; Kaiser, Adrien; Ahn, Mihye; Johnson, Hans; Matsui, Joy; Hazlett, Heather C; Sharma, Anuja; Goodlett, Casey; Shi, Yundi; Gouttard, Sylvain; Vachet, Clement; Piven, Joseph; Zhu, Hongtu; Gerig, Guido; Styner, Martin

    2014-01-01

    Diffusion tensor imaging has become an important modality in the field of neuroimaging to capture changes in micro-organization and to assess white matter integrity or development. While there exists a number of tractography toolsets, these usually lack tools for preprocessing or to analyze diffusion properties along the fiber tracts. Currently, the field is in critical need of a coherent end-to-end toolset for performing an along-fiber tract analysis, accessible to non-technical neuroimaging researchers. The UNC-Utah NA-MIC DTI framework represents a coherent, open source, end-to-end toolset for atlas fiber tract based DTI analysis encompassing DICOM data conversion, quality control, atlas building, fiber tractography, fiber parameterization, and statistical analysis of diffusion properties. Most steps utilize graphical user interfaces (GUI) to simplify interaction and provide an extensive DTI analysis framework for non-technical researchers/investigators. We illustrate the use of our framework on a small sample, cross sectional neuroimaging study of eight healthy 1-year-old children from the Infant Brain Imaging Study (IBIS) Network. In this limited test study, we illustrate the power of our method by quantifying the diffusion properties at 1 year of age on the genu and splenium fiber tracts.

  14. Quantitative analysis of diffusion tensor imaging (DTI) using statistical parametric mapping (SPM) for brain disorders

    Science.gov (United States)

    Lee, Jae-Seung; Im, In-Chul; Kang, Su-Man; Goo, Eun-Hoe; Kwak, Byung-Joon

    2013-07-01

    This study aimed to quantitatively analyze data from diffusion tensor imaging (DTI) using statistical parametric mapping (SPM) in patients with brain disorders and to assess its potential utility for analyzing brain function. DTI was obtained by performing 3.0-T magnetic resonance imaging for patients with Alzheimer's disease (AD) and vascular dementia (VD), and the data were analyzed using Matlab-based SPM software. The two-sample t-test was used for error analysis of the location of the activated pixels. We compared regions of white matter where the fractional anisotropy (FA) values were low and the apparent diffusion coefficients (ADCs) were increased. In the AD group, the FA values were low in the right superior temporal gyrus, right inferior temporal gyrus, right sub-lobar insula, and right occipital lingual gyrus whereas the ADCs were significantly increased in the right inferior frontal gyrus and right middle frontal gyrus. In the VD group, the FA values were low in the right superior temporal gyrus, right inferior temporal gyrus, right limbic cingulate gyrus, and right sub-lobar caudate tail whereas the ADCs were significantly increased in the left lateral globus pallidus and left medial globus pallidus. In conclusion by using DTI and SPM analysis, we were able to not only determine the structural state of the regions affected by brain disorders but also quantitatively analyze and assess brain function.

  15. Structural brain alterations of Down's syndrome in early childhood evaluation by DTI and volumetric analyses

    International Nuclear Information System (INIS)

    Gunbey, Hediye Pinar; Bilgici, Meltem Ceyhan; Aslan, Kerim; Incesu, Lutfi; Has, Arzu Ceylan; Ogur, Methiye Gonul; Alhan, Aslihan

    2017-01-01

    To provide an initial assessment of white matter (WM) integrity with diffusion tensor imaging (DTI) and the accompanying volumetric changes in WM and grey matter (GM) through volumetric analyses of young children with Down's syndrome (DS). Ten children with DS and eight healthy control subjects were included in the study. Tract-based spatial statistics (TBSS) were used in the DTI study for whole-brain voxelwise analysis of fractional anisotropy (FA) and mean diffusivity (MD) of WM. Volumetric analyses were performed with an automated segmentation method to obtain regional measurements of cortical volumes. Children with DS showed significantly reduced FA in association tracts of the fronto-temporo-occipital regions as well as the corpus callosum (CC) and anterior limb of the internal capsule (p < 0.05). Volumetric reductions included total cortical GM, cerebellar GM and WM volume, basal ganglia, thalamus, brainstem and CC in DS compared with controls (p < 0.05). These preliminary results suggest that DTI and volumetric analyses may reflect the earliest complementary changes of the neurodevelopmental delay in children with DS and can serve as surrogate biomarkers of the specific elements of WM and GM integrity for cognitive development. (orig.)

  16. Diffusion tensor imaging and neuromodulation: DTI as key technology for deep brain stimulation.

    Science.gov (United States)

    Coenen, Volker Arnd; Schlaepfer, Thomas E; Allert, Niels; Mädler, Burkhard

    2012-01-01

    Diffusion tensor imaging (DTI) is more than just a useful adjunct to invasive techniques like optogenetics which recently have tremendously influenced our understanding of the mechanisms of deep brain stimulation (DBS). In combination with other technologies, DTI helps us to understand which parts of the brain tissue are connected to others and which ones are truly influenced with neuromodulation. The complex interaction of DBS with the surrounding tissues-scrutinized with DTI-allows to create testable hypotheses that can explain network interactions. Those interactions are vital for our understanding of the net effects of neuromodulation. This work naturally was first done in the field of movement disorder surgery, where a lot of experience regarding therapeutic effects and only a short latency between initiation of neuromodulation and alleviation of symptoms exist. This chapter shows the journey over the past 10 years with first applications in DBS toward current research in affect regulating network balances and their therapeutic alterations with the neuromodulation technology. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Preoperative DTI and probabilistic tractography in an amputee with deep brain stimulation for lower limb stump pain.

    Science.gov (United States)

    Owen, S L F; Heath, J; Kringelbach, M L; Stein, J F; Aziz, T Z

    2007-10-01

    This study aimed to find out whether preoperative diffusion tensor imaging (DTI) and probabilistic tractography could help with surgical planning for deep brain stimulation in the periaqueductal/periventricular grey area (PAG/PVG) in a patient with lower leg stump pain. A preoperative DTI was obtained from the patient, who then received DBS surgery in the PAG/PVG area with good pain relief. The postoperative MRI scan showing electrode placement was used to calculate four seed areas to represent the contacts on the Medtronic 3387 electrode. Probabilistic tractography was then performed from the pre-operative DTI image. Tracts were seen to connect to many areas within the pain network from the four different contacts. These initial findings suggest that preoperative DTI scanning and probabilistic tractography may be able to assist surgical planning in the future.

  18. Mutual information-based LPI optimisation for radar network

    Science.gov (United States)

    Shi, Chenguang; Zhou, Jianjiang; Wang, Fei; Chen, Jun

    2015-07-01

    Radar network can offer significant performance improvement for target detection and information extraction employing spatial diversity. For a fixed number of radars, the achievable mutual information (MI) for estimating the target parameters may extend beyond a predefined threshold with full power transmission. In this paper, an effective low probability of intercept (LPI) optimisation algorithm is presented to improve LPI performance for radar network. Based on radar network system model, we first provide Schleher intercept factor for radar network as an optimisation metric for LPI performance. Then, a novel LPI optimisation algorithm is presented, where for a predefined MI threshold, Schleher intercept factor for radar network is minimised by optimising the transmission power allocation among radars in the network such that the enhanced LPI performance for radar network can be achieved. The genetic algorithm based on nonlinear programming (GA-NP) is employed to solve the resulting nonconvex and nonlinear optimisation problem. Some simulations demonstrate that the proposed algorithm is valuable and effective to improve the LPI performance for radar network.

  19. A code for optimising triplet layout

    CERN Document Server

    AUTHOR|(CDS)2141109; Seryi, Andrei; Abelleira, Jose; Cruz Alaniz, Emilia

    2017-01-01

    One of the main challenges when designing final focus systems of particle accelerators is maximising the beam stay clear in the strong quadrupole magnets of the inner triplet. Moreover it is desirable to keep the quadrupoles in the inner triplet as short as possible for space and costs reasons but also to reduce chromaticity and simplify corrections schemes. An algorithm that explores the triplet parameter space to optimise both these aspects was written. It uses thin lenses as a first approximation for a broad parameter scan and MADX for more precise calculations. The thin lens algorithm is significantly faster than a full scan using MADX and relatively precise at indicating the approximate area where the optimum solution lies.

  20. Evaluation of low-grade glioma structural changes after chemotherapy using DTI-based histogram analysis and functional diffusion maps

    Energy Technology Data Exchange (ETDEWEB)

    Castellano, Antonella; Iadanza, Antonella; Falini, Andrea [San Raffaele Scientific Institute and Vita-Salute San Raffaele University, Neuroradiology Unit and CERMAC, Milano (Italy); Donativi, Marina [University of Salento, Department of Mathematics and Physics ' ' Ennio De Giorgi' ' and A.D.A.M. (Advanced Data Analysis in Medicine), Lecce (Italy); Ruda, Roberta; Bertero, Luca; Soffietti, Riccardo [University of Torino, Department of Neuro-oncology, Turin (Italy); De Nunzio, Giorgio [University of Salento, Department of Mathematics and Physics ' ' Ennio De Giorgi' ' and A.D.A.M. (Advanced Data Analysis in Medicine), Lecce (Italy); INFN (National Institute of Nuclear Physics), Lecce (Italy); Riva, Marco; Bello, Lorenzo [Universita degli Studi di Milano, Milan, and Humanitas Research Hospital, Department of Medical Biotechnology and Translational Medicine, Rozzano, MI (Italy); Rucco, Matteo [University of Camerino, School of Science and Technology, Computer Science Division, Camerino, MC (Italy)

    2016-05-15

    To explore the role of diffusion tensor imaging (DTI)-based histogram analysis and functional diffusion maps (fDMs) in evaluating structural changes of low-grade gliomas (LGGs) receiving temozolomide (TMZ) chemotherapy. Twenty-one LGG patients underwent 3T-MR examinations before and after three and six cycles of dose-dense TMZ, including 3D-fluid-attenuated inversion recovery (FLAIR) sequences and DTI (b = 1000 s/mm{sup 2}, 32 directions). Mean diffusivity (MD), fractional anisotropy (FA), and tensor-decomposition DTI maps (p and q) were obtained. Histogram and fDM analyses were performed on co-registered baseline and post-chemotherapy maps. DTI changes were compared with modifications of tumour area and volume [according to Response Assessment in Neuro-Oncology (RANO) criteria], and seizure response. After three cycles of TMZ, 20/21 patients were stable according to RANO criteria, but DTI changes were observed in all patients (Wilcoxon test, P ≤ 0.03). After six cycles, DTI changes were more pronounced (P ≤ 0.005). Seventy-five percent of patients had early seizure response with significant improvement of DTI values, maintaining stability on FLAIR. Early changes of the 25th percentiles of p and MD predicted final volume change (R{sup 2} = 0.614 and 0.561, P < 0.0005, respectively). TMZ-related changes were located mainly at tumour borders on p and MD fDMs. DTI-based histogram and fDM analyses are useful techniques to evaluate the early effects of TMZ chemotherapy in LGG patients. (orig.)

  1. Cogeneration technologies, optimisation and implementation

    CERN Document Server

    Frangopoulos, Christos A

    2017-01-01

    Cogeneration refers to the use of a power station to deliver two or more useful forms of energy, for example, to generate electricity and heat at the same time. This book provides an integrated treatment of cogeneration, including a tour of the available technologies and their features, and how these systems can be analysed and optimised.

  2. For Time-Continuous Optimisation

    DEFF Research Database (Denmark)

    Heinrich, Mary Katherine; Ayres, Phil

    2016-01-01

    Strategies for optimisation in design normatively assume an artefact end-point, disallowing continuous architecture that engages living systems, dynamic behaviour, and complex systems. In our Flora Robotica investigations of symbiotic plant-robot bio-hybrids, we re- quire computational tools...

  3. Design of passive coolers for light-emitting diode lamps using topology optimisation

    DEFF Research Database (Denmark)

    Alexandersen, Joe; Sigmund, Ole; Meyer, Knud Erik

    2018-01-01

    Topology optimised designs for passive cooling of light-emitting diode (LED) lamps are investigated through extensive numerical parameter studies. The designs are optimised for either horizontal or vertical orientations and are compared to a lattice-fin design as well as a simple parameter......, while maintaining low sensitivity to orientation. Furthermore, they exhibit several defining features and provide insight and general guidelines for the design of passive coolers for LED lamps....

  4. High-temperature superconducting fault-current limiter - optimisation of superconducting elements

    International Nuclear Information System (INIS)

    2004-01-01

    This report summarises the findings of a study initiated to continue the work of a DTI-LINK Collaborative Research Programme 'Enhancing the Properties of Bulk High Temperature Superconductors and their Potential Application as Fault Current Limiters (FCL). Details are given of computer modelling of the quenching process involving the transition from superconducting to normal conducting states undergone by the material when large currents are present. The design of compound elements, and a multi-element model are described along with FCL design covering distribution bus-coupler, embedded generator connection, larger generator connection, hazardous area safety, and interconnection to fault-prone network. The evaluation of thermal loss, test equipment and schedule, the optimised element, installed cost data, and the UK market are considered

  5. PHYSICAL-MATEMATICALSCIENCE MECHANICS SIMULATION CHALLENGES IN OPTIMISING THEORETICAL METAL CUTTING TASKS

    Directory of Open Access Journals (Sweden)

    Rasul V. Guseynov

    2017-01-01

    Full Text Available Abstract. Objectives In the article, problems in the optimising of machining operations, which provide end-unit production of the required quality with a minimum processing cost, are addressed. Methods Increasing the effectiveness of experimental research was achieved through the use of mathematical methods for planning experiments for optimising metal cutting tasks. The minimal processing cost model, in which the objective function is polynomial, is adopted as a criterion for the selection of optimal parameters. Results Polynomial models of the influence of angles φ, α, γ on the torque applied when cutting threads in various steels are constructed. Optimum values of the geometrical tool parameters were obtained using the criterion of minimum cutting forces during processing. The high stability of tools having optimal geometric parameters is determined. It is shown that the use of experimental planning methods allows the optimisation of cutting parameters. In optimising solutions to metal cutting problems, it is found to be expedient to use multifactor experimental planning methods and to select the cutting force as the optimisation parameter when determining tool geometry. Conclusion The joint use of geometric programming and experiment planning methods in order to optimise the parameters of cutting significantly increases the efficiency of technological metal processing approaches. 

  6. Language pathway tracking: comparing nTMS-based DTI fiber tracking with a cubic ROIs-based protocol.

    Science.gov (United States)

    Negwer, Chiara; Sollmann, Nico; Ille, Sebastian; Hauck, Theresa; Maurer, Stefanie; Kirschke, Jan S; Ringel, Florian; Meyer, Bernhard; Krieg, Sandro M

    2017-03-01

    OBJECTIVE Diffusion tensor imaging (DTI) fiber tracking (FT) has been widely used in glioma surgery in recent years. It can provide helpful information about subcortical structures, especially in patients with eloquent space-occupying lesions. This study compared the newly developed navigated transcranial magnetic stimulation (nTMS)-based DTI FT of language pathways with the most reproducible protocol for language pathway tractography, using cubic regions of interest (ROIs) for the arcuate fascicle. METHODS Thirty-seven patients with left-sided perisylvian lesions underwent language mapping by repetitive nTMS. DTI FT was performed using the cubic ROIs-based protocol and the authors' nTMS-based DTI FT approach. The same minimal fiber length and fractional anisotropy were chosen (50 mm and 0.2, respectively). Both protocols were performed with standard clinical tractography software. RESULTS Both methods visualized language-related fiber tracts (i.e., corticonuclear tract, arcuate fascicle, uncinate fascicle, superior longitudinal fascicle, inferior longitudinal fascicle, arcuate fibers, commissural fibers, corticothalamic fibers, and frontooccipital fascicle) in all 37 patients. Using the cubic ROIs-based protocol, 39.9% of these language-related fiber tracts were detected in the examined patients, as opposed to 76.0% when performing nTMS-based DTI FT. For specifically tracking the arcuate fascicle, however, the cubic ROIs-based approach showed better results (97.3% vs 75.7% with nTMS-based DTI FT). CONCLUSIONS The cubic ROIs-based protocol was designed for arcuate fascicle tractography, and this study shows that it is still useful for this intention. However, superior results were obtained using the nTMS-based DTI FT for visualization of other language-related fiber tracts.

  7. Demyelinating evidences in CMS rat model of depression: a DTI study at 7 T.

    Science.gov (United States)

    Hemanth Kumar, B S; Mishra, S K; Trivedi, R; Singh, S; Rana, P; Khushu, S

    2014-09-05

    Depression is among the most debilitating diseases worldwide. Long-term exposure to stressors plays a major role in development of human depression. Chronic mild stress (CMS) seems to be a valid animal model for depression. Diffusion tensor imaging (DTI) is capable of inferring microstructural abnormalities of the white matter and has shown to serve as non-invasive marker of specific pathology. We developed a CMS rat model of depression and validated with behavioral experiments. We measured the diffusion indices (mean diffusivity (MD), fractional anisotropy (FA), axial (λ∥) and radial (λ⊥) diffusivity) to investigate the changes in CMS rat brain during depression onset. Diffusion indices have shown to be useful to discriminate myelin damage from axon loss. DTI was performed in both control and CMS rats (n=10, in each group) and maps of FA, MD, λ∥ and λ⊥ diffusivity values were generated using in-house built software. The diffusion indices were calculated by region of interest (ROI) analysis in different brain regions like the frontal cortex, hippocampus, hypothalamus, cingulum, thalamus, caudate putamen, corpus callosum, cerebral peduncle and sensory motor cortex. The results showed signs of demyelination, reflected by increased MD, decreased FA and increased λ⊥. The results also suggest a possible role of edema or inflammation concerning the brain morphology in CMS rats. The overall finding using DTI suggests there might be a major role of loss of myelin sheath, which leads to disrupted connectivity between the limbic area and the prefrontal cortex during the onset of depression. Our findings indicate that interpretation of these indices may provide crucial information about the type and severity of mood disorders. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

  8. Functional MRI, DTI and neurophysiology in horizontal gaze palsy with progressive scoliosis

    Energy Technology Data Exchange (ETDEWEB)

    Haller, Sven; Wetzel, Stephan G. [University Hospital Basel, Institute of Radiology, Department of Neuroradiology, Basel (Switzerland); Luetschg, Juerg [University Children' s Hospital (UKBB), Basel (Switzerland)

    2008-05-15

    Horizontal gaze palsy with progressive scoliosis (HGPPS) is an autosomal recessive disease due to a mutation in the ROBO3 gene. This rare disease is of particular interest because the absence, or at least reduction, of crossing of the ascending lemniscal and descending corticospinal tracts in the medulla predicts abnormal ipsilateral sensory and motor systems. We evaluated the use of functional magnetic resonance imaging (fMRI) for the first time in this disease and compared it to diffusion tensor imaging (DTI) tractography and neurophysiological findings in the same patient with genetically confirmed ROBO3 mutation. As expected, motor fMRI, somatosensory evoked potentials (SSEP) and motor evoked potentials (MEP) were dominantly ipsilateral to the stimulation side. DTI tractography revealed ipsilateral ascending and descending connectivity in the brainstem yet normal interhemispheric connections in the corpus callosum. Auditory fMRI revealed bilateral auditory activation to monaural left-sided auditory stimulation. No significant cortical activation was observed after monaural right-sided stimulation, a hearing defect having been excluded. Prosaccades fMRI showed no activations in the eye-movement network. Motor fMRI confirmed the established findings of DTI and neurophysiology in the same patient. In suspected HGPPS, any technique appears appropriate for further investigation. Auditory fMRI suggests that a monaural auditory system with bilateral auditory activations might be a physiological advantage as compared to a binaural yet only unilateral auditory system, in analogy to anisometropic amblyopia. Moving-head fMRI studies in the future might show whether the compensatory head movements instead of normal eye movements activate the eye-movement network. (orig.)

  9. Functional MRI, DTI and neurophysiology in horizontal gaze palsy with progressive scoliosis

    International Nuclear Information System (INIS)

    Haller, Sven; Wetzel, Stephan G.; Luetschg, Juerg

    2008-01-01

    Horizontal gaze palsy with progressive scoliosis (HGPPS) is an autosomal recessive disease due to a mutation in the ROBO3 gene. This rare disease is of particular interest because the absence, or at least reduction, of crossing of the ascending lemniscal and descending corticospinal tracts in the medulla predicts abnormal ipsilateral sensory and motor systems. We evaluated the use of functional magnetic resonance imaging (fMRI) for the first time in this disease and compared it to diffusion tensor imaging (DTI) tractography and neurophysiological findings in the same patient with genetically confirmed ROBO3 mutation. As expected, motor fMRI, somatosensory evoked potentials (SSEP) and motor evoked potentials (MEP) were dominantly ipsilateral to the stimulation side. DTI tractography revealed ipsilateral ascending and descending connectivity in the brainstem yet normal interhemispheric connections in the corpus callosum. Auditory fMRI revealed bilateral auditory activation to monaural left-sided auditory stimulation. No significant cortical activation was observed after monaural right-sided stimulation, a hearing defect having been excluded. Prosaccades fMRI showed no activations in the eye-movement network. Motor fMRI confirmed the established findings of DTI and neurophysiology in the same patient. In suspected HGPPS, any technique appears appropriate for further investigation. Auditory fMRI suggests that a monaural auditory system with bilateral auditory activations might be a physiological advantage as compared to a binaural yet only unilateral auditory system, in analogy to anisometropic amblyopia. Moving-head fMRI studies in the future might show whether the compensatory head movements instead of normal eye movements activate the eye-movement network. (orig.)

  10. Magnetic resonance imaging DTI-FT study on schizophrenic patients with typical negative first symptoms.

    Science.gov (United States)

    Gu, Chengyu; Zhang, Ying; Wei, Fuquan; Cheng, Yougen; Cao, Yulin; Hou, Hongtao

    2016-09-01

    Magnetic resonance imaging (MRI) with diffusion-tensor imaging (DTI) together with a white matter fiber tracking (FT) technique was used to assess different brain white matter structures and functionalities in schizophrenic patients with typical first negative symptoms. In total, 30 schizophrenic patients with typical first negative symptoms, comprising an observation group were paired 1:1 according to gender, age, right-handedness, and education, with 30 healthy individuals in a control group. Individuals in each group underwent routine MRI and DTI examination of the brain, and diffusion-tensor tractography (DTT) data were obtained through whole brain analysis based on voxel and tractography. The results were expressed by fractional anisotropy (FA) values. The schizophrenic patients were evaluated using a positive and negative symptom scale (PANSS) as well as a Global Assessment Scale (GAS). The results of the study showed that routine MRIs identified no differences between the two groups. However, compared with the control group, the FA values obtained by DTT from the deep left prefrontal cortex, the right deep temporal lobe, the white matter of the inferior frontal gyrus and part of the corpus callosum were significantly lower in the observation group (Pscale value in the observation group averaged 7.7±1.5, and the negative scale averaged 46.6±5.9, while the general psychopathology scale averaged 65.4±10.3, and GAS averaged 53.8±19.2. The Pearson statistical analysis, the left deep prefrontal cortex, the right deep temporal lobe, the white matter of the inferior frontal gyrus and the FA value of part of the corpus callosum in the observation group was negatively correlated with the negative scale (Pnegative symptoms and the application of MRI DTI-FT can improve diagnostic accuracy.

  11. Functional MRI, DTI and neurophysiology in horizontal gaze palsy with progressive scoliosis.

    Science.gov (United States)

    Haller, Sven; Wetzel, Stephan G; Lütschg, Jürg

    2008-05-01

    Horizontal gaze palsy with progressive scoliosis (HGPPS) is an autosomal recessive disease due to a mutation in the ROBO3 gene. This rare disease is of particular interest because the absence, or at least reduction, of crossing of the ascending lemniscal and descending corticospinal tracts in the medulla predicts abnormal ipsilateral sensory and motor systems. We evaluated the use of functional magnetic resonance imaging (fMRI) for the first time in this disease and compared it to diffusion tensor imaging (DTI) tractography and neurophysiological findings in the same patient with genetically confirmed ROBO3 mutation. As expected, motor fMRI, somatosensory evoked potentials (SSEP) and motor evoked potentials (MEP) were dominantly ipsilateral to the stimulation side. DTI tractography revealed ipsilateral ascending and descending connectivity in the brainstem yet normal interhemispheric connections in the corpus callosum. Auditory fMRI revealed bilateral auditory activation to monaural left-sided auditory stimulation. No significant cortical activation was observed after monaural right-sided stimulation, a hearing defect having been excluded. Prosaccades fMRI showed no activations in the eye-movement network. Motor fMRI confirmed the established findings of DTI and neurophysiology in the same patient. In suspected HGPPS, any technique appears appropriate for further investigation. Auditory fMRI suggests that a monaural auditory system with bilateral auditory activations might be a physiological advantage as compared to a binaural yet only unilateral auditory system, in analogy to anisometropic amblyopia. Moving-head fMRI studies in the future might show whether the compensatory head movements instead of normal eye movements activate the eye-movement network.

  12. Optimisation of Multilayer Insulation an Engineering Approach

    CERN Document Server

    Chorowski, M; Parente, C; Riddone, G

    2001-01-01

    A mathematical model has been developed to describe the heat flux through multilayer insulation (MLI). The total heat flux between the layers is the result of three distinct heat transfer modes: radiation, residual gas conduction and solid spacer conduction. The model describes the MLI behaviour considering a layer-to-layer approach and is based on an electrical analogy, in which the three heat transfer modes are treated as parallel thermal impedances. The values of each of the transfer mode vary from layer to layer, although the total heat flux remains constant across the whole MLI blanket. The model enables the optimisation of the insulation with regard to different MLI parameters, such as residual gas pressure, number of layers and boundary temperatures. The model has been tested with experimental measurements carried out at CERN and the results revealed to be in a good agreement, especially for insulation vacuum between 10-5 Pa and 10-3 Pa.

  13. Optimising Comprehensibility in Interlingual Translation

    DEFF Research Database (Denmark)

    Nisbeth Jensen, Matilde

    2015-01-01

    The increasing demand for citizen engagement in areas traditionally belonging exclusively to experts, such as health, law and technology has given rise to the necessity of making expert knowledge available to the general public through genres such as instruction manuals for consumer goods, patien...... the functional text type of Patient Information Leaflet. Finally, the usefulness of applying the principles of Plain Language and intralingual translation for optimising comprehensibility in interlingual translation is discussed....

  14. Feasibility of the use of optimisation techniques to calibrate the models used in a post-closure radiological assessment

    International Nuclear Information System (INIS)

    Laundy, R.S.

    1991-01-01

    This report addresses the feasibility of the use of optimisation techniques to calibrate the models developed for the impact assessment of a radioactive waste repository. The maximum likelihood method for improving parameter estimates is considered in detail, and non-linear optimisation techniques for finding solutions are reviewed. Applications are described for the calibration of groundwater flow, radionuclide transport and biosphere models. (author)

  15. MARCHIAFAVA-BIGNAMI DISEASE (MBD AND DIFFUSION TENSOR IMAGE (DTI TRACTOGRAPHY

    Directory of Open Access Journals (Sweden)

    Priscilla Chukwueke

    2015-06-01

    Full Text Available Marchiafava-Bignami Disease (MBD is a rare central nervous system (CNS disease characterized by demyelination of the corpus callosum. It is mostly found in men with alcohol use disorder and malnutrition with cases reported worldwide across all races. The onset of the disease may be sudden presenting with stupor, coma or seizures while some may present with gait abnormality (spasticity, psychiatric problems, hemiparesis, aphasia, apraxia and incontinence with a resultant high morbidity and mortality rates. Case description: patient is a 30 year old left handed African-American, who presented with c/o altered mental status, urinary incontinence, slurred speech and left-sided weakness. The diagnosis of MBD was confirmed with DTI Tractography which showed significantly diminished commissural fibers extending to the right central semiovale lesion, near absent or significantly diminished commissural fiber extending through the corpus callosum indicating demyelination. Discussion: MBD is often an incidental diagnosis with high morbidity and mortality. This is different from previous casas because of earlier onset as opposed to onset around age 45, rapid recovery and minimal disability as he could walk independently before discharge from hospital. This case also shows added benefit of the DTI tractography in the diagnosis of MBD.

  16. Visualizing whole-brain DTI tractography with GPU-based Tuboids and LoD management.

    Science.gov (United States)

    Petrovic, Vid; Fallon, James; Kuester, Falko

    2007-01-01

    Diffusion Tensor Imaging (DTI) of the human brain, coupled with tractography techniques, enable the extraction of large-collections of three-dimensional tract pathways per subject. These pathways and pathway bundles represent the connectivity between different brain regions and are critical for the understanding of brain related diseases. A flexible and efficient GPU-based rendering technique for DTI tractography data is presented that addresses common performance bottlenecks and image-quality issues, allowing interactive render rates to be achieved on commodity hardware. An occlusion query-based pathway LoD management system for streamlines/streamtubes/tuboids is introduced that optimizes input geometry, vertex processing, and fragment processing loads, and helps reduce overdraw. The tuboid, a fully-shaded streamtube impostor constructed entirely on the GPU from streamline vertices, is also introduced. Unlike full streamtubes and other impostor constructs, tuboids require little to no preprocessing or extra space over the original streamline data. The supported fragment processing levels of detail range from texture-based draft shading to full raycast normal computation, Phong shading, environment mapping, and curvature-correct text labeling. The presented text labeling technique for tuboids provides adaptive, aesthetically pleasing labels that appear attached to the surface of the tubes. Furthermore, an occlusion query aggregating and scheduling scheme for tuboids is described that reduces the query overhead. Results for a tractography dataset are presented, and demonstrate that LoD-managed tuboids offer benefits over traditional streamtubes both in performance and appearance.

  17. Optimization of the scintillation parameters of the lead tungstate crystals for their application in high precision electromagnetic calorimetry; Optimisation des parametres de scintillation des cristaux de tungstate de plomb pour leur application dans la calorimetrie electromagnetique de haute precision

    Energy Technology Data Exchange (ETDEWEB)

    Drobychev, G

    2000-04-12

    In the frame of this dissertation work scintillation properties of the lead tungstate crystals (PWO) and possibilities of their use were studied foreseeing their application for electromagnetic calorimetry in extreme radiation environment conditions of new colliders. The results of this work can be summarized in the following way. 1. A model of the scintillations origin in the lead tungstate crystals which includes processes influencing on the crystals radiation hardness and presence of slow components in scintillations was developed. 2. An analysis of the influences of the PWO scintillation properties changes on the parameters of the electromagnetic calorimeter was done. 3. Methods of the light collection from the large scintillation elements of complex shape made of the birefringent scintillation crystal with high refraction index and low light yield in case of signal registration by a photodetector with sensitive surface small in compare with the output face of scintillator were Studied. 4. Physical principles of the methodology of the scintillation crystals certification during their mass production foreseeing their installation into a calorimeter electromagnetic were developed. Correlations between the results of measurements of the PWO crystals parameters by different methods were found. (author)

  18. The Inertia Weight Updating Strategies in Particle Swarm Optimisation Based on the Beta Distribution

    Directory of Open Access Journals (Sweden)

    Petr Maca

    2015-01-01

    Full Text Available The presented paper deals with the comparison of selected random updating strategies of inertia weight in particle swarm optimisation. Six versions of particle swarm optimization were analysed on 28 benchmark functions, prepared for the Special Session on Real-Parameter Single Objective Optimisation at CEC2013. The random components of tested inertia weight were generated from Beta distribution with different values of shape parameters. The best analysed PSO version is the multiswarm PSO, which combines two strategies of updating the inertia weight. The first is driven by the temporally varying shape parameters, while the second is based on random control of shape parameters of Beta distribution.

  19. A study of certain Monte Carlo search and optimisation methods

    International Nuclear Information System (INIS)

    Budd, C.

    1984-11-01

    Studies are described which might lead to the development of a search and optimisation facility for the Monte Carlo criticality code MONK. The facility envisaged could be used to maximise a function of k-effective with respect to certain parameters of the system or, alternatively, to find the system (in a given range of systems) for which that function takes a given value. (UK)

  20. Optimising Boltzmann codes for the PLANCK era

    International Nuclear Information System (INIS)

    Hamann, Jan; Lesgourgues, Julien; Balbi, Amedeo; Quercellini, Claudia

    2009-01-01

    High precision measurements of the Cosmic Microwave Background (CMB) anisotropies, as can be expected from the PLANCK satellite, will require high-accuracy theoretical predictions as well. One possible source of theoretical uncertainty is the numerical error in the output of the Boltzmann codes used to calculate angular power spectra. In this work, we carry out an extensive study of the numerical accuracy of the public Boltzmann code CAMB, and identify a set of parameters which determine the error of its output. We show that at the current default settings, the cosmological parameters extracted from data of future experiments like Planck can be biased by several tenths of a standard deviation for the six parameters of the standard ΛCDM model, and potentially more seriously for extended models. We perform an optimisation procedure that leads the code to achieve sufficient precision while at the same time keeping the computation time within reasonable limits. Our conclusion is that the contribution of numerical errors to the theoretical uncertainty of model predictions is well under control—the main challenges for more accurate calculations of CMB spectra will be of an astrophysical nature instead

  1. An Optimisation Approach for Room Acoustics Design

    DEFF Research Database (Denmark)

    Holm-Jørgensen, Kristian; Kirkegaard, Poul Henning; Andersen, Lars

    2005-01-01

    This paper discuss on a conceptual level the value of optimisation techniques in architectural acoustics room design from a practical point of view. It is chosen to optimise one objective room acoustics design criterium estimated from the sound field inside the room. The sound field is modeled...... using the boundary element method where absorption is incorporated. An example is given where the geometry of a room is defined by four design modes. The room geometry is optimised to get a uniform sound pressure....

  2. TU-CD-BRB-05: Radiation Damage Signature of White Matter Fiber Bundles Using Diffusion Tensor Imaging (DTI)

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, T; Chapman, C; Lawrence, T; Cao, Y [University of Michigan, Ann Arbor, MI (United States); Tsien, C [Washington University at St. Louis, St. Louis, MO (United States)

    2015-06-15

    Purpose: To develop an automated and scalable approach and identify temporal, spatial and dosimetric patterns of radiation damage of white matter (WM) fibers following partial brain irradiation. Methods: An automated and scalable approach was developed to extract DTI features of 22 major WM fibers from 33 patients with low-grade/benign tumors treated by radiation therapy (RT). DTI scans of the patients were performed pre-RT, 3- and 6-week during RT, and 1, 6 and 18 months after RT. The automated tractography analysis was applied to 198 datasets as: (1) intra-subject registration of longitudinal DTI, (2) spatial normalization of individual-patient DTI to the Johns Hopkins WM Atlas, (3) automatic fiber tracking regulated by the WM Atlas, and (4) segmentation of WM into 22 major tract profiles. Longitudinal percentage changes in fractional anisotropy (FA), and mean, axial and radial diffusivity (MD/AD/RD) of each tract from pre-RT were quantified and correlated to 95%, 90% and 80% percentiles of doses and mean doses received by the tract. Heatmaps were used to identify clusters of significant correlation and reveal temporal, spatial and dosimetric signatures of WM damage. A multivariate linear regression was further carried out to determine influence of clinical factors. Results: Of 22 tracts, AD/MD changes in 12 tracts had significant correlation with doses, especially at 6 and 18 months post-RT, indicating progressive radiation damage after RT. Most interestingly, the DTI-index changes in the elongated tracts were associated with received maximum doses, suggesting a serial-structure behavior; while short association fibers were affected by mean doses, indicating a parallel-structure response. Conclusion: Using an automated DTI-tractography analysis of whole brain WM fibers, we reveal complex radiation damage patterns of WM fibers. Damage in WM fibers that play an important role in the neural network could be associated with late neurocognitive function declines

  3. Metal Removal Process Optimisation using Taguchi Method - Simplex Algorithm (TM-SA) with Case Study Applications

    OpenAIRE

    Ajibade, Oluwaseyi A.; Agunsoye, Johnson O.; Oke, Sunday A.

    2018-01-01

    In the metal removal process industry, the current practice to optimise cutting parameters adoptsa conventional method. It is based on trial and error, in which the machine operator uses experience,coupled with handbook guidelines to determine optimal parametric values of choice. This method is notaccurate, is time-consuming and costly. Therefore, there is a need for a method that is scientific, costeffectiveand precise. Keeping this in mind, a different direction for process optimisation is ...

  4. Optimisation combinatoire Theorie et algorithmes

    CERN Document Server

    Korte, Bernhard; Fonlupt, Jean

    2010-01-01

    Ce livre est la traduction fran aise de la quatri me et derni re dition de Combinatorial Optimization: Theory and Algorithms crit par deux minents sp cialistes du domaine: Bernhard Korte et Jens Vygen de l'universit de Bonn en Allemagne. Il met l accent sur les aspects th oriques de l'optimisation combinatoire ainsi que sur les algorithmes efficaces et exacts de r solution de probl mes. Il se distingue en cela des approches heuristiques plus simples et souvent d crites par ailleurs. L ouvrage contient de nombreuses d monstrations, concises et l gantes, de r sultats difficiles. Destin aux tudia

  5. Diagnostic value of conventional MRI combined with DTI for neonatal hyperbilirubinemia

    Directory of Open Access Journals (Sweden)

    Ruifang Yan

    2018-04-01

    Full Text Available Background: Neonatal hyperbilirubinemia (NHB is a common clinical disease and can cause bilirubin encephalopathy in severe cases. It is now widely accepted that increased signal intensity in the globus pallidus on MR T1WI is an important sign of neonatal bilirubin encephalopathy. And brain diffusion tensor imaging (DTI has not been used extensively to study hyperbilirubinemia (HB. So we compared newborns with different hyperbilirubinemia of different severities and healthy newborns in order to determine the relationships among MRI signal intensities, serum bilirubin levels, and the molecular changes in brain water diffusion in hyperbilirubinemia. Methods: Seventy-three newborns with hyperbilirubinemia were grouped into three groups: the mild increase group (M, 27 cases, the moderate increase group (O, 28 cases, and the severe group (S, 18 cases. The groups were based on serum bilirubin levels. We performed cranial MRI in these newborns, as well as 29 healthy full-term infants (group N. We compared and analyzed the mean signal values for the globus pallidus and the relationship between the bilirubin level and the score on the neonatal behavioral neurological assessment. Fifteen, 10, and 10 patients in groups M, O + S, and N were successfully examined using diffusion tensor imaging (DTI. We assessed the relationships among the signal from the globus pallidus, fractional anisotropy (FA, and average diffusion coefficient (DCav of the posterior limb of the internal capsule (PLIC. Results: There were significant differences in the mean signal value of bilateral globus pallidus between group O/S and group N [p = 0.029 and 0.000 (left, 0.038 and 0.000 (right]. There were no significant differences in bilateral FA or DCav values between the patient groups and group N. The bilateral PLIC-FA and DCav values were significantly different between the patient groups and group N (P = 0.014 and 0.047, respectively. Conclusions: Increased signal intensity

  6. Structural MRI research in patients with nasopharyngeal carcinoma following radiotherapy: A DTI and VBM study.

    Science.gov (United States)

    Leng, Xi; Fang, Peng; Lin, Huan; An, Jie; Tan, Xin; Zhang, Chi; Wu, Donglin; Shen, Wen; Qiu, Shijun

    2017-11-01

    The aim of the present study was to investigate the microstructural characteristics of the brain lobes following radiotherapy (RT) for patients with nasopharyngeal carcinoma (NPC) at distinct times. Diffusion tensor imaging (DTI) and 3D-T1-weighted imaging was performed in 70 age- and sex-matched subjects, 24 of whom were pre-treatment patients. The patients were divided into three groups, according to the time following completion of RT. Fractional anisotropy (FA) and gray matter (GM) volume were determined. The DTI data were analyzed using tract-based spatial statistics and the GM volume was analyzed using voxel-based morphometry (VBM). Compared with the pre-RT group, the mean FA values in the left parietal lobe white matter (WM) and right cerebellum decreased significantly in the post-RT 0-6 month group (P<0.05). In addition, the mean FA values in the right parietal lobe WM decreased significantly in the post-RT 6-12 month group (P<0.05), compared with the pre-RT group. The FA level in the right temporal lobe remained significantly decreased, compared with that in the pre-RT group (P<0.05) for 1 year after RT. Furthermore, compared with pre-RT group, the GM volume in the bilateral frontal lobe, right occipital lobe, left parietal lobe, right temporal lobe and left cerebellum decreased significantly in the post-RT 0-6 month group (P<0.05), and in the bilateral temporal lobe, parietal lobe, right frontal lobe and left cerebellum, the GM volume decreased significantly in the post-RT 6-12 month group (P<0.05). The GM volume in the right temporal lobe, bilateral frontal lobe and bilateral cerebellum remained significantly decreased compared with that in the pre-RT group (P<0.05) for 1 year after RT. A combination of DTI and VBM may be used to determine radiation-induced brain injury in patients treated for NPC.

  7. Optimising resource management in neurorehabilitation.

    Science.gov (United States)

    Wood, Richard M; Griffiths, Jeff D; Williams, Janet E; Brouwers, Jakko

    2014-01-01

    To date, little research has been published regarding the effective and efficient management of resources (beds and staff) in neurorehabilitation, despite being an expensive service in limited supply. To demonstrate how mathematical modelling can be used to optimise service delivery, by way of a case study at a major 21 bed neurorehabilitation unit in the UK. An automated computer program for assigning weekly treatment sessions is developed. Queue modelling is used to construct a mathematical model of the hospital in terms of referral submissions to a waiting list, admission and treatment, and ultimately discharge. This is used to analyse the impact of hypothetical strategic decisions on a variety of performance measures and costs. The project culminates in a hybridised model of these two approaches, since a relationship is found between the number of therapy hours received each week (scheduling output) and length of stay (queuing model input). The introduction of the treatment scheduling program has substantially improved timetable quality (meaning a better and fairer service to patients) and has reduced employee time expended in its creation by approximately six hours each week (freeing up time for clinical work). The queuing model has been used to assess the effect of potential strategies, such as increasing the number of beds or employing more therapists. The use of mathematical modelling has not only optimised resources in the short term, but has allowed the optimality of longer term strategic decisions to be assessed.

  8. Study on the evolutionary optimisation of the topology of network control systems

    Science.gov (United States)

    Zhou, Zude; Chen, Benyuan; Wang, Hong; Fan, Zhun

    2010-08-01

    Computer networks have been very popular in enterprise applications. However, optimisation of network designs that allows networks to be used more efficiently in industrial environment and enterprise applications remains an interesting research topic. This article mainly discusses the topology optimisation theory and methods of the network control system based on switched Ethernet in an industrial context. Factors that affect the real-time performance of the industrial control network are presented in detail, and optimisation criteria with their internal relations are analysed. After the definition of performance parameters, the normalised indices for the evaluation of the topology optimisation are proposed. The topology optimisation problem is formulated as a multi-objective optimisation problem and the evolutionary algorithm is applied to solve it. Special communication characteristics of the industrial control network are considered in the optimisation process. In respect to the evolutionary algorithm design, an improved arena algorithm is proposed for the construction of the non-dominated set of the population. In addition, for the evaluation of individuals, the integrated use of the dominative relation method and the objective function combination method, for reducing the computational cost of the algorithm, are given. Simulation tests show that the performance of the proposed algorithm is preferable and superior compared to other algorithms. The final solution greatly improves the following indices: traffic localisation, traffic balance and utilisation rate balance of switches. In addition, a new performance index with its estimation process is proposed.

  9. Algorithm for optimisation of paediatric chest radiography

    International Nuclear Information System (INIS)

    Kostova-Lefterova, D.

    2016-01-01

    The purpose of this work is to assess the current practice and patient doses in paediatric chest radiography in a large university hospital. The X-ray unit is used in the paediatric department for respiratory diseases. Another purpose was to recommend and apply optimized protocols to reduce patient dose while maintaining diagnostic image quality for the x-ray images. The practice of two different radiographers was studied. The results were compared with the existing practice in paediatric chest radiography and the opportunities for optimization were identified in order to reduce patient doses. A methodology was developed for optimization of the x-ray examinations by grouping children in age groups or according to other appropriate indication and creating an algorithm for proper selection of the exposure parameters for each group. The algorithm for the optimisation of paediatric chest radiography reduced patient doses (PKA, organ dose, effective dose) between 1.5 and 6 times for the different age groups, the average glandular dose up to 10 times and the dose for the lung between 2 and 5 times. The resulting X-ray images were of good diagnostic quality. The subjectivity in the choice of exposure parameters was reduced and standardization has been achieved in the work of the radiographers. The role of the radiologist, the medical physicist and radiographer in the process of optimization was shown. It was proven the effect of teamwork in reducing patient doses at keeping adequate image quality. Key words: Chest Radiography. Paediatric Radiography. Optimization. Radiation Exposure. Radiation Protection

  10. Diffusion tensor MR imaging (DTI) metrics in the cervical spinal cord in asymptomatic HIV-positive patients

    Energy Technology Data Exchange (ETDEWEB)

    Mueller-Mang, Christina; Mang, Thomas; Fruehwald-Pallamar, Julia; Weber, Michael; Thurnher, Majda M. [Medical University of Vienna, Department of Radiology, Vienna (Austria); Law, Meng [University of Southern California, Los Angeles County Hospital and USC Medical Center, Department of Radiology, Keck School of Medicine, Los Angeles, CA (United States)

    2011-08-15

    This study was conducted to compare diffusion tensor MR imaging (DTI) metrics of the cervical spinal cord in asymptomatic human immunodeficiency virus (HIV)-positive patients with those measured in healthy volunteers, and to assess whether DTI is a valuable diagnostic tool in the early detection of HIV-associated myelopathy (HIVM). MR imaging of the cervical spinal cord was performed in 20 asymptomatic HIV-positive patients and in 20 healthy volunteers on a 3-T MR scanner. Average fractional anisotropy (FA), mean diffusivity (MD), and major (E1) and minor (E2, E3) eigenvalues were calculated within regions of interest (ROIs) at the C2/3 level (central and bilateral anterior, lateral and posterior white matter). Statistical analysis showed significant differences with regard to mean E3 values between patients and controls (p = 0.045; mixed-model analysis of variance (ANOVA) test). Mean FA was lower, and mean MD, mean E1, and mean E2 were higher in each measured ROI in patients compared to controls, but these differences were not statistically significant. Asymptomatic HIV-positive patients demonstrate only subtle changes in DTI metrics measured in the cervical spinal cord compared to healthy volunteers that currently do not support using DTI as a diagnostic tool for the early detection of HIVM. (orig.)

  11. Optimisation of VSC-HVDC Transmission for Wind Power Plants

    DEFF Research Database (Denmark)

    Silva, Rodrigo Da

    Connection of Wind Power Plants (WPP), typically oshore, using VSCHVDC transmission is an emerging solution with many benefits compared to the traditional AC solution, especially concerning the impact on control architecture of the wind farms and the grid. The VSC-HVDC solution is likely to meet...... more stringent grid codes than a conventional AC transmission connection. The purpose of this project is to analyse how HVDC solution, considering the voltage-source converter based technology, for grid connection of large wind power plants can be designed and optimised. By optimisation, the project...... the robust control technique is applied is compared with the classical proportional-integral (PI) performance, by means of time domain simulation in a point-to-point HVDC connection. The three main parameters in the discussion are the wind power delivered from the offshore wind power plant, the variation...

  12. Dose optimisation in computed radiography

    International Nuclear Information System (INIS)

    Schreiner-Karoussou, A.

    2005-01-01

    After the installation of computed radiography (CR) systems in three hospitals in Luxembourg a patient dose survey was carried out for three radiographic examinations, thorax, pelvis and lumbar spine. It was found that the patient doses had changed in comparison with the patient doses measured for conventional radiography in the same three hospitals. A close collaboration between the manufacturers of the X-ray installations, the CR imaging systems and the medical physicists led to the discovery that the speed class with which each radiographic examination was to be performed, had been ignored, during installation of the digital imaging systems. A number of procedures were carried out in order to calibrate and program the X-ray installations in conjunction with the CR systems. Following this optimisation procedure, a new patient dose survey was carried out for the three radiographic examinations. It was found that patient doses for the three hospitals were reduced. (authors)

  13. Optimising costs in WLCG operations

    CERN Document Server

    Pradillo, Mar; Flix, Josep; Forti, Alessandra; Sciabà, Andrea

    2015-01-01

    The Worldwide LHC Computing Grid project (WLCG) provides the computing and storage resources required by the LHC collaborations to store, process and analyse the 50 Petabytes of data annually generated by the LHC. The WLCG operations are coordinated by a distributed team of managers and experts and performed by people at all participating sites and from all the experiments. Several improvements in the WLCG infrastructure have been implemented during the first long LHC shutdown to prepare for the increasing needs of the experiments during Run2 and beyond. However, constraints in funding will affect not only the computing resources but also the available effort for operations. This paper presents the results of a detailed investigation on the allocation of the effort in the different areas of WLCG operations, identifies the most important sources of inefficiency and proposes viable strategies for optimising the operational cost, taking into account the current trends in the evolution of the computing infrastruc...

  14. The role of DTI in early detection of cervical spondylotic myelopathy: a preliminary study with 3-T MRI

    Energy Technology Data Exchange (ETDEWEB)

    Kara, Batuhan [Bakirkoey Dr. Sadi Konuk Teaching Hospital, Department of Radiology, Istanbul (Turkey); Celik, Azim [General Electric Healthcare, Istanbul (Turkey); Karadereler, Selhan [Florence Nightingale Hospital, Department of Neurosurgery, Istanbul (Turkey); Ulusoy, Levent; Ganiyusufoglu, Kursat; Onat, Levent; Mutlu, Ayhan; Sirvanci, Mustafa [Florence Nightingale Hospital, Department of Radiology, Istanbul (Turkey); Ornek, Ibrahim [Florence Nightingale Hospital, Department of Neurology, Istanbul (Turkey); Hamzaoglu, Azmi [Florence Nightingale Hospital, Department of Orthopedic Surgery, Istanbul (Turkey)

    2011-08-15

    The radiological diagnosis of cervical spondylotic myelopathy (CSM) has to be made as soon as possible, since surgery performed in earlier stages during the course of CSM was reported to be more successful when compared with later stages. We hypothesized that diffusion tensor imaging (DTI) may detect CSM in earlier stages, before the appearance of signal increase in T2-weighted sequences. A total of 16 patients with neurological signs and symptoms of CSM but without hyperintensity in spinal cord on T2-weighted sequences enrolled in the study. The magnetic resonance (MR) examinations were performed on a 3-T MR imaging system. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) maps were generated on axial plane. The ADC and FA measurements in each individual were made at the level of most severe cervical canal stenosis and at a nonstenotic level. Student's t test was used to compare FA and ADC values of the spinal cord in stenotic and nonstenotic segments. We also investigated if there was a correlation between DTI parametrics and duration of clinical symptoms by using Pearson correlation analysis. All patients showed changes in DTI parametrics at stenotic segments. While FA values of the spinal cord at the stenotic level showed a statistically significant reduction, there was a statistically significant increase in the measured ADC values (p < 0.001). There was no statistical correlation between the duration of symptoms and DTI parametrics. Our preliminary findings indicate that DTI may show abnormalities in the spinal cord before the development of T2 hyperintensity on conventional sequences in patients with CSM. (orig.)

  15. The role of DTI in early detection of cervical spondylotic myelopathy: a preliminary study with 3-T MRI

    International Nuclear Information System (INIS)

    Kara, Batuhan; Celik, Azim; Karadereler, Selhan; Ulusoy, Levent; Ganiyusufoglu, Kursat; Onat, Levent; Mutlu, Ayhan; Sirvanci, Mustafa; Ornek, Ibrahim; Hamzaoglu, Azmi

    2011-01-01

    The radiological diagnosis of cervical spondylotic myelopathy (CSM) has to be made as soon as possible, since surgery performed in earlier stages during the course of CSM was reported to be more successful when compared with later stages. We hypothesized that diffusion tensor imaging (DTI) may detect CSM in earlier stages, before the appearance of signal increase in T2-weighted sequences. A total of 16 patients with neurological signs and symptoms of CSM but without hyperintensity in spinal cord on T2-weighted sequences enrolled in the study. The magnetic resonance (MR) examinations were performed on a 3-T MR imaging system. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) maps were generated on axial plane. The ADC and FA measurements in each individual were made at the level of most severe cervical canal stenosis and at a nonstenotic level. Student's t test was used to compare FA and ADC values of the spinal cord in stenotic and nonstenotic segments. We also investigated if there was a correlation between DTI parametrics and duration of clinical symptoms by using Pearson correlation analysis. All patients showed changes in DTI parametrics at stenotic segments. While FA values of the spinal cord at the stenotic level showed a statistically significant reduction, there was a statistically significant increase in the measured ADC values (p < 0.001). There was no statistical correlation between the duration of symptoms and DTI parametrics. Our preliminary findings indicate that DTI may show abnormalities in the spinal cord before the development of T2 hyperintensity on conventional sequences in patients with CSM. (orig.)

  16. Optimisation of Forming Parameters to Reach Near Net Shape

    DEFF Research Database (Denmark)

    Ravn, Bjarne Gottlieb; Wanheim, Tarras

    2000-01-01

    Demands to the manufacturing industry have always been that the overall production expenses for a given component should be decreased. In the metal forming area, one way to reduce the expenses is to increase the complexity of the component and to reduce the number of steps in the production and t...

  17. Optimisation of design parameters for modular range enhanced projectile

    OpenAIRE

    Jelic, Z

    2016-01-01

    There is an underpinning requirement for artillery systems to achieve longer range, better precision, and an adequate lethal effect. The main objective of this research is to investigate various methods of range increase and propose optimal solution for range extension of existing artillery systems. The proposed solution is novel, modular projectile design. Several methodologies for projectile range increment (such as improved aerodynamics and ballistic profile) were combined to achieve the "...

  18. The DTI FSU Nuclear legacy programme: UK experience of radiation protection at Andreeva Bay

    International Nuclear Information System (INIS)

    Hammon, C.; Parker, R.

    2006-01-01

    Full text of publication follows: The United Kingdom (UK) has committed substantial long term funding to the Former Soviet Union (FSU) to assist with their nuclear legacy as part of the UK contribution to the G8 Global Partnership. The budget is managed by the UK Department of Trade and Industry (DTI) and RWE NUKEM are the programme management consultants for the Nuclear Legacy programme, which includes the Andreeva Bay project. The fundamental driver for the DTI is to improve the safety, security and non-proliferation of fissile material and RWE NUKEM is working closely with the DTI to achieve this. Andreeva Bay is located in the extreme north -west of the Kola Peninsula in Russia. The site was established in the 1960's to be used for the interim storage of used nuclear fuel, and solid and liquid radioactive wastes arising from the operation of nuclear powered submarines and icebreakers. However, leakage in the spent fuel pond storage facility during the late 1970's resulted in the emergency transfer of the fuel (20,000 spent fuel assemblies) to 3 dry storage tanks, which are now in very poor condition, and a highly contaminated pond storage facility, Building 5. The objectives of the project are to identify and implement solutions for the existing safety, security and environmental problems of SNF. One of the tasks at Andreeva Bay was to work together with the Russian site operators with the aim of improving standards of radiation protection on the site. This is being achieved by providing the Russians with funding to enable them to implement measures to improve radiological safety. The following measures have been put in place so far: the introduction of a Radiation Management System, the provision of mobile and permanent staff change room facilities, the provision of decontamination facilities, the provision of radiation protection instrumentation, the provision of laboratory facilities, the provision of secondary waste storage containers, the provision of

  19. Statistical optimisation techniques in fatigue signal editing problem

    International Nuclear Information System (INIS)

    Nopiah, Z. M.; Osman, M. H.; Baharin, N.; Abdullah, S.

    2015-01-01

    Success in fatigue signal editing is determined by the level of length reduction without compromising statistical constraints. A great reduction rate can be achieved by removing small amplitude cycles from the recorded signal. The long recorded signal sometimes renders the cycle-to-cycle editing process daunting. This has encouraged researchers to focus on the segment-based approach. This paper discusses joint application of the Running Damage Extraction (RDE) technique and single constrained Genetic Algorithm (GA) in fatigue signal editing optimisation.. In the first section, the RDE technique is used to restructure and summarise the fatigue strain. This technique combines the overlapping window and fatigue strain-life models. It is designed to identify and isolate the fatigue events that exist in the variable amplitude strain data into different segments whereby the retention of statistical parameters and the vibration energy are considered. In the second section, the fatigue data editing problem is formulated as a constrained single optimisation problem that can be solved using GA method. The GA produces the shortest edited fatigue signal by selecting appropriate segments from a pool of labelling segments. Challenges arise due to constraints on the segment selection by deviation level over three signal properties, namely cumulative fatigue damage, root mean square and kurtosis values. Experimental results over several case studies show that the idea of solving fatigue signal editing within a framework of optimisation is effective and automatic, and that the GA is robust for constrained segment selection

  20. Statistical optimisation techniques in fatigue signal editing problem

    Energy Technology Data Exchange (ETDEWEB)

    Nopiah, Z. M.; Osman, M. H. [Fundamental Engineering Studies Unit Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM (Malaysia); Baharin, N.; Abdullah, S. [Department of Mechanical and Materials Engineering Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 UKM (Malaysia)

    2015-02-03

    Success in fatigue signal editing is determined by the level of length reduction without compromising statistical constraints. A great reduction rate can be achieved by removing small amplitude cycles from the recorded signal. The long recorded signal sometimes renders the cycle-to-cycle editing process daunting. This has encouraged researchers to focus on the segment-based approach. This paper discusses joint application of the Running Damage Extraction (RDE) technique and single constrained Genetic Algorithm (GA) in fatigue signal editing optimisation.. In the first section, the RDE technique is used to restructure and summarise the fatigue strain. This technique combines the overlapping window and fatigue strain-life models. It is designed to identify and isolate the fatigue events that exist in the variable amplitude strain data into different segments whereby the retention of statistical parameters and the vibration energy are considered. In the second section, the fatigue data editing problem is formulated as a constrained single optimisation problem that can be solved using GA method. The GA produces the shortest edited fatigue signal by selecting appropriate segments from a pool of labelling segments. Challenges arise due to constraints on the segment selection by deviation level over three signal properties, namely cumulative fatigue damage, root mean square and kurtosis values. Experimental results over several case studies show that the idea of solving fatigue signal editing within a framework of optimisation is effective and automatic, and that the GA is robust for constrained segment selection.

  1. Numerical optimisation of an axial turbine; Numerische Optimierung einer Axialturbine

    Energy Technology Data Exchange (ETDEWEB)

    Welzel, B.

    1998-12-31

    The author presents a method for automatic shape optimisation of components with internal or external flow. The method combines a program for numerical calculation of frictional turbulent flow with an optimisation algorithm. Algorithms are a simplex search strategy and an evolution strategy. The shape of the component to be optimized is variable due to shape parameters modified by the algorithm. For each shape, a flow calculation is carried out on whose basis a functional value like performance, loss, lift or resistivity is calculated. For validation, the optimisation method is used in simple examples with known solutions. It is applied. It is applied to the components of a slow-running axial turbine. Components with accelerated and delayed rotationally symmetric flow and 2D blade profiles are optimized. [Deutsch] Es wird eine Methode zur automatischen Formoptimierung durchstroemter oder umstroemter Bauteile vorgestellt. Diese koppelt ein Programm zur numerischen Berechnung reibungsbehafteter turbulenter Stroemungen mit einem Optimierungsalgorithmus. Dabei kommen als Algorithmen eine Simplex-Suchstrategie und eine Evolutionsstrategie zum Einsatz. Die Form des zu optimierenden Koerpers ist durch Formparameter, die vom Algorithmus veraendert werden, variabel. Fuer jede Form wird eine Stroemungsberechnung durchgefuehrt und mit dieser ein Funktionswert wie Wirkungsgrad, Verlust, Auftrieb oder Widerstandskraft berechnet. Die Optimierungsmethode wird zur Validierung in einfachen Beispielen mit bekannter Loesung eingesetzt. Zur Anwendung kommt sie in den einzelnen Komponenten einer langsamlaeufigen Axialturbine. Es werden Bauteile mit beschleunigter und verzoegerter rotationssymmetrischer Stroemung und 2D-Schaufelprofile optimiert. (orig.)

  2. Compensatory Shift of Subcallosal Area and Paraterminal Gyrus White Matter Parameters on DTI in Patients with Alzheimer Disease.

    Science.gov (United States)

    Kuchtova, Barbora; Wurst, Zdenek; Mrzilkova, Jana; Ibrahim, Ibrahim; Tintera, Jaroslav; Bartos, Ales; Musil, Vladimir; Kieslich, Karel; Zach, Petr

    2018-01-01

    Alzheimer disease is traditionally conceptualized as a disease of brain gray matter, however, studies with diffusion tensor imaging have demonstrated that Alzheimer disease also involves alterations in white matter integrity. We measured number of tracts, tracts length, tract volume, quantitative anisotropy and general fractional anisotropy of neuronal tracts in subcallosal area, paraterminal gyrus and fornix in patients with Alzheimer disease and healthy age-matched controls. Our hypothesis was that patients with Alzheimer disease should exhibit decrease in the integrity of these white matter structures that are crucial for semantic memory function. For our study were selected 24 patients with confirmed Alzheimer disease diagnosis and 24 healthy controls (AD center, Department of Neurology, Charles University, Prague, Czech Republic). Statistically significant differences between the patients with Alzheimer disease and the control group were found both on the left and right fornices but only concerning the tract numbers and tract length. The subcallosal area and paraterminal gyrus showed statistically significant differences between the patients with Alzheimer disease and the control group, but only on the left side and only associated with the tract volume and quantitative anisotropy. Our explanation for these findings lies in the severe hippocampal atrophy (and subsequent loss of function) with compensatory hypertrophy of the subcallosal area and paraterminal gyrus neuronal fibers that occurs in Alzheimer's disease, as an adaptation to the loss of projection from the hippocampal formation via fornix. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  3. Tracking the Re-organization of Motor Functions After Disconnective Surgery: A Longitudinal fMRI and DTI Study

    Directory of Open Access Journals (Sweden)

    Cristina Rosazza

    2018-06-01

    Full Text Available Objective: Mechanisms of motor plasticity are critical to maintain motor functions after cerebral damage. This study explores the mechanisms of motor reorganization occurring before and after surgery in four patients with drug-refractory epilepsy candidate to disconnective surgery.Methods: We studied four patients with early damage, who underwent tailored hemispheric surgery in adulthood, removing the cortical motor areas and disconnecting the corticospinal tract (CST from the affected hemisphere. Motor functions were assessed clinically, with functional MRI (fMRI tasks of arm and leg movement and Diffusion Tensor Imaging (DTI before and after surgery with assessments of up to 3 years. Quantifications of fMRI motor activations and DTI fractional anisotropy (FA color maps were performed to assess the lateralization of motor network. We hypothesized that lateralization of motor circuits assessed preoperatively with fMRI and DTI was useful to evaluate the motor outcome in these patients.Results: In two cases preoperative DTI-tractography did not reconstruct the CST, and FA-maps were strongly asymmetric. In the other two cases, the affected CST appeared reduced compared to the contralateral one, with modest asymmetry in the FA-maps. fMRI showed different degrees of lateralization of the motor network and the SMA of the intact hemisphere was mostly engaged in all cases. After surgery, patients with a strongly lateralized motor network showed a stable performance. By contrast, a patient with a more bilateral pattern showed worsening of the upper limb function. For all cases, fMRI activations shifted to the intact hemisphere. Structural alterations of motor circuits, observed with FA values, continued beyond 1 year after surgery.Conclusion: In our case series fMRI and DTI could track the longitudinal reorganization of motor functions. In these four patients the more the paretic limbs recruited the intact hemisphere in primary motor and associative

  4. Tracking the Re-organization of Motor Functions After Disconnective Surgery: A Longitudinal fMRI and DTI Study.

    Science.gov (United States)

    Rosazza, Cristina; Deleo, Francesco; D'Incerti, Ludovico; Antelmi, Luigi; Tringali, Giovanni; Didato, Giuseppe; Bruzzone, Maria G; Villani, Flavio; Ghielmetti, Francesco

    2018-01-01

    Objective: Mechanisms of motor plasticity are critical to maintain motor functions after cerebral damage. This study explores the mechanisms of motor reorganization occurring before and after surgery in four patients with drug-refractory epilepsy candidate to disconnective surgery. Methods: We studied four patients with early damage, who underwent tailored hemispheric surgery in adulthood, removing the cortical motor areas and disconnecting the corticospinal tract (CST) from the affected hemisphere. Motor functions were assessed clinically, with functional MRI (fMRI) tasks of arm and leg movement and Diffusion Tensor Imaging (DTI) before and after surgery with assessments of up to 3 years. Quantifications of fMRI motor activations and DTI fractional anisotropy (FA) color maps were performed to assess the lateralization of motor network. We hypothesized that lateralization of motor circuits assessed preoperatively with fMRI and DTI was useful to evaluate the motor outcome in these patients. Results: In two cases preoperative DTI-tractography did not reconstruct the CST, and FA-maps were strongly asymmetric. In the other two cases, the affected CST appeared reduced compared to the contralateral one, with modest asymmetry in the FA-maps. fMRI showed different degrees of lateralization of the motor network and the SMA of the intact hemisphere was mostly engaged in all cases. After surgery, patients with a strongly lateralized motor network showed a stable performance. By contrast, a patient with a more bilateral pattern showed worsening of the upper limb function. For all cases, fMRI activations shifted to the intact hemisphere. Structural alterations of motor circuits, observed with FA values, continued beyond 1 year after surgery. Conclusion: In our case series fMRI and DTI could track the longitudinal reorganization of motor functions. In these four patients the more the paretic limbs recruited the intact hemisphere in primary motor and associative areas, the

  5. Combining simulation and multi-objective optimisation for equipment quantity optimisation in container terminals

    OpenAIRE

    Lin, Zhougeng

    2013-01-01

    This thesis proposes a combination framework to integrate simulation and multi-objective optimisation (MOO) for container terminal equipment optimisation. It addresses how the strengths of simulation and multi-objective optimisation can be integrated to find high quality solutions for multiple objectives with low computational cost. Three structures for the combination framework are proposed respectively: pre-MOO structure, integrated MOO structure and post-MOO structure. The applications of ...

  6. Pre-Industry-Optimisation of the Laser Welding Process

    DEFF Research Database (Denmark)

    Gong, Hui

    This dissertation documents the investigations into on-line monitoring the CO2 laser welding process and optimising the process parameters for achieving high quality welds. The requirements for realisation of an on-line control system are, first of all, a clear understanding of the dynamic...... phenomena of the laser welding process including the behaviour of the keyhole and plume, and the correlation between the adjustable process parameters: laser power, welding speed, focal point position, gas parameters etc. and the characteristics describing the quality of the weld: seam depth and width......, porosity etc. Secondly, a reliable monitoring system for sensing the laser-induced plasma and plume emission and detecting weld defects and process parameter deviations from the optimum conditions. Finally, an efficient control system with a fast signal processor and a precise feed-back controller...

  7. Topology optimisation of natural convection problems

    DEFF Research Database (Denmark)

    Alexandersen, Joe; Aage, Niels; Andreasen, Casper Schousboe

    2014-01-01

    This paper demonstrates the application of the density-based topology optimisation approach for the design of heat sinks and micropumps based on natural convection effects. The problems are modelled under the assumptions of steady-state laminar flow using the incompressible Navier-Stokes equations...... coupled to the convection-diffusion equation through the Boussinesq approximation. In order to facilitate topology optimisation, the Brinkman approach is taken to penalise velocities inside the solid domain and the effective thermal conductivity is interpolated in order to accommodate differences...... in thermal conductivity of the solid and fluid phases. The governing equations are discretised using stabilised finite elements and topology optimisation is performed for two different problems using discrete adjoint sensitivity analysis. The study shows that topology optimisation is a viable approach...

  8. Topology Optimisation for Coupled Convection Problems

    DEFF Research Database (Denmark)

    Alexandersen, Joe

    This thesis deals with topology optimisation for coupled convection problems. The aim is to extend and apply topology optimisation to steady-state conjugate heat transfer problems, where the heat conduction equation governs the heat transfer in a solid and is coupled to thermal transport...... in a surrounding uid, governed by a convection-diffusion equation, where the convective velocity field is found from solving the isothermal incompressible steady-state Navier-Stokes equations. Topology optimisation is also applied to steady-state natural convection problems. The modelling is done using stabilised...... finite elements, the formulation and implementation of which was done partly during a special course as prepatory work for this thesis. The formulation is extended with a Brinkman friction term in order to facilitate the topology optimisation of fluid flow and convective cooling problems. The derived...

  9. Benchmarks for dynamic multi-objective optimisation

    CSIR Research Space (South Africa)

    Helbig, M

    2013-06-01

    Full Text Available When algorithms solve dynamic multi-objective optimisation problems (DMOOPs), benchmark functions should be used to determine whether the algorithm can overcome specific difficulties that can occur in real-world problems. However, for dynamic multi...

  10. Credit price optimisation within retail banking

    African Journals Online (AJOL)

    2014-02-14

    Feb 14, 2014 ... cost based pricing, where the price of a product or service is based on the .... function obtained from fitting a logistic regression model .... Note that the proposed optimisation approach below will allow us to also incorporate.

  11. User perspectives in public transport timetable optimisation

    DEFF Research Database (Denmark)

    Jensen, Jens Parbo; Nielsen, Otto Anker; Prato, Carlo Giacomo

    2014-01-01

    The present paper deals with timetable optimisation from the perspective of minimising the waiting time experienced by passengers when transferring either to or from a bus. Due to its inherent complexity, this bi-level minimisation problem is extremely difficult to solve mathematically, since tim...... on the large-scale public transport network in Denmark. The timetable optimisation approach yielded a yearly reduction in weighted waiting time equivalent to approximately 45 million Danish kroner (9 million USD)....

  12. Optimisation: how to develop stake holder involvement

    International Nuclear Information System (INIS)

    Weiss, W.

    2003-01-01

    The Precautionary Principle is an internationally recognised approach for dealing with risk situations characterised by uncertainties and potential irreversible damages. Since the late fifties, ICRP has adopted this prudent attitude because of the lack of scientific evidence concerning the existence of a threshold at low doses for stochastic effects. The 'linear, no-threshold' model and the 'optimisation of protection' principle have been developed as a pragmatic response for the management of the risk. The progress in epidemiology and radiobiology over the last decades have affirmed the initial assumption and the optimisation remains the appropriate response for the application of the precautionary principle in the context of radiological protection. The basic objective of optimisation is, for any source within the system of radiological protection, to maintain the level of exposure as low as reasonably achievable, taking into account social and economical factors. Methods tools and procedures have been developed over the last two decades to put into practice the optimisation principle with a central role given to the cost-benefit analysis as a means to determine the optimised level of protection. However, with the advancement in the implementation of the principle more emphasis was progressively given to good practice, as well as on the importance of controlling individual levels of exposure through the optimisation process. In the context of the revision of its present recommendations, the Commission is reenforcing the emphasis on protection of the individual with the adoption of an equity-based system that recognizes individual rights and a basic level of health protection. Another advancement is the role that is now recognised to 'stakeholders involvement' in the optimisation process as a mean to improve the quality of the decision aiding process for identifying and selecting protection actions considered as being accepted by all those involved. The paper

  13. Analysis of correlation between white matter changes and functional responses in thalamic stroke: a DTI & EEG study.

    Science.gov (United States)

    Duru, Adil Deniz; Duru, Dilek Göksel; Yumerhodzha, Sami; Bebek, Nerses

    2016-06-01

    Diffusion tensor imaging (DTI) allows in vivo structural brain mapping and detection of microstructural disruption of white matter (WM). One of the commonly used parameters for grading the anisotropic diffusivity in WM is fractional anisotropy (FA). FA value helps to quantify the directionality of the local tract bundle. Therefore, FA images are being used in voxelwise statistical analyses (VSA). The present study used Tract-Based Spatial Statistics (TBSS) of FA images across subjects, and computes the mean skeleton map to detect voxelwise knowledge of the tracts yielding to groupwise comparison. The skeleton image illustrates WM structure and shows any changes caused by brain damage. The microstructure of WM in thalamic stroke is investigated, and the VSA results of healthy control and thalamic stroke patients are reported. It has been shown that several skeleton regions were affected subject to the presence of thalamic stroke (FWE, p EEG (qEEG) scores and neurophysiological tests with the FA skeleton for the entire test group is also investigated. We compared measurements that are related to the same fibers across subjects, and discussed implications for VSA of WM in thalamic stroke cases, for the relationship between behavioral tests and FA skeletons, and for the correlation between the FA maps and qEEG scores.Results obtained through the regression analyses did not exceed the corrected statistical threshold values for multiple comparisons (uncorrected, p EEG, cingulum bundle and corpus callosum were found to be related. These areas are parts of the Default Mode Network (DMN) where DMN is known to be involved in resting state EEG theta activity. The relation between the EEG alpha band power values and FA values of the skeleton was found to support the cortico-thalamocortical cycles for both subject groups. Further, the neurophysiological tests including Benton Face Recognition (BFR), Digit Span test (DST), Warrington Topographic Memory test (WTMT

  14. Predicting the laterality of temporal lobe epilepsy from PET, MRI, and DTI: A multimodal study

    Directory of Open Access Journals (Sweden)

    Dorian Pustina

    2015-01-01

    Full Text Available Pre-surgical evaluation of patients with temporal lobe epilepsy (TLE relies on information obtained from multiple neuroimaging modalities. The relationship between modalities and their combined power in predicting the seizure focus is currently unknown. We investigated asymmetries from three different modalities, PET (glucose metabolism, MRI (cortical thickness, and diffusion tensor imaging (DTI; white matter anisotropy in 28 left and 30 right TLE patients (LTLE and RTLE. Stepwise logistic regression models were built from each modality separately and from all three combined, while bootstrapped methods and split-sample validation verified the robustness of predictions. Among all multimodal asymmetries, three PET asymmetries formed the best predictive model (100% success in full sample, >95% success in split-sample validation. The combinations of PET with other modalities did not perform better than PET alone. Probabilistic classifications were obtained for new clinical cases, which showed correct lateralization for 7/7 new TLE patients (100% and for 4/5 operated patients with discordant or non-informative PET reports (80%. Metabolism showed closer relationship with white matter in LTLE and closer relationship with gray matter in RTLE. Our data suggest that metabolism is a powerful modality that can predict seizure laterality with high accuracy, and offers high value for automated predictive models. The side of epileptogenic focus can affect the relationship of metabolism with brain structure. The data and tools necessary to obtain classifications for new TLE patients are made publicly available.

  15. A preliminary DTI study showing no brain structural change associated with adolescent cannabis use

    Directory of Open Access Journals (Sweden)

    Brown Kyle

    2006-05-01

    Full Text Available Abstract Analyses were performed on brain MRI scans from individuals who were frequent cannabis users (N = 10; 9 males, 1 female, mean age 21.1 ± 2.9, range: 18–27 in adolescence and similar age and sex matched young adults who never used cannabis (N = 10; 9 males, 1 female, mean age of 23.0 ± 4.4, range: 17–30. Cerebral atrophy and white matter integrity were determined using diffusion tensor imaging (DTI to quantify the apparent diffusion coefficient (ADC and the fractional anisotropy (FA. Whole brain volumes, lateral ventricular volumes, and gray matter volumes of the amygdala-hippocampal complex, superior temporal gyrus, and entire temporal lobes (excluding the amygdala-hippocampal complex were also measured. While differences existed between groups, no pattern consistent with evidence of cerebral atrophy or loss of white matter integrity was detected. It is concluded that frequent cannabis use is unlikely to be neurotoxic to the normal developing adolescent brain.

  16. Improved olefinic fat suppression in skeletal muscle DTI using a magnitude-based dixon method.

    Science.gov (United States)

    Burakiewicz, Jedrzej; Hooijmans, Melissa T; Webb, Andrew G; Verschuuren, Jan J G M; Niks, Erik H; Kan, Hermien E

    2018-01-01

    To develop a method of suppressing the multi-resonance fat signal in diffusion-weighted imaging of skeletal muscle. This is particularly important when imaging patients with muscular dystrophies, a group of diseases which cause gradual replacement of muscle tissue by fat. The signal from the olefinic fat peak at 5.3 ppm can significantly confound diffusion-tensor imaging measurements. Dixon olefinic fat suppression (DOFS), a magnitude-based chemical-shift-based method of suppressing the olefinic peak, is proposed. It is verified in vivo by performing diffusion tensor imaging (DTI)-based quantification in the lower leg of seven healthy volunteers, and compared to two previously described fat-suppression techniques in regions with and without fat contamination. In the region without fat contamination, DOFS produces similar results to existing techniques, whereas in muscle contaminated by subcutaneous fat signal moved due to the chemical shift artefact, it consistently showed significantly higher (P = 0.018) mean diffusivity (MD). Because fat presence lowers MD, this suggests improved fat suppression. DOFS offers superior fat suppression and enhances quantitative measurements in the muscle in the presence of fat. DOFS is an alternative to spectral olefinic fat suppression. Magn Reson Med 79:152-159, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  17. White matter alterations in the brains of patients with active, remitted, and cured cushing syndrome: a DTI study.

    Science.gov (United States)

    Pires, P; Santos, A; Vives-Gilabert, Y; Webb, S M; Sainz-Ruiz, A; Resmini, E; Crespo, I; de Juan-Delago, M; Gómez-Anson, B

    2015-06-01

    Cushing syndrome appears after chronic exposure to elevated glucocorticoid levels. Cortisol excess may alter white matter microstructure. Our purpose was to study WM changes in patients with Cushing syndrome compared with controls by using DTI and the influence of hypercortisolism. Thirty-five patients with Cushing syndrome and 35 healthy controls, matched for age, education, and sex, were analyzed through DTI (tract-based spatial statistics) for fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity (general linear model, family-wise error, and threshold-free cluster enhancement corrections, P Cushing syndrome with active hypercortisolism, 7 with Cushing syndrome with medication-remitted cortisol, 20 surgically cured, and 35 controls. Cardiovascular risk factors were used as covariates. In addition, correlations were analyzed among DTI values, concomitant 24-hour urinary free cortisol levels, and disease duration. There were widespread alterations (reduced fractional anisotropy, and increased mean diffusivity, axial diffusivity, and radial diffusivity values; P Cushing syndrome compared with controls, independent of the cardiovascular risk factors present. Both active and cured Cushing syndrome subgroups showed similar changes compared with controls. Patients with medically remitted Cushing syndrome also had reduced fractional anisotropy and increased mean diffusivity and radial diffusivity values, compared with controls. No correlations were found between DTI maps and 24-hour urinary free cortisol levels or with disease duration. Diffuse WM alterations in patients with Cushing syndrome suggest underlying loss of WM integrity and demyelination. Once present, they seem to be independent of concomitant hypercortisolism, persisting after remission/cure. © 2015 by American Journal of Neuroradiology.

  18. Identifying the white matter impairments among ART-naive HIV patients: a multivariate pattern analysis of DTI data

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Zhenchao [Shandong University, School of Mechanical, Electrical and Information Engineering, Weihai, Shandong Province (China); Institute of Automation, CAS Key Laboratory of Molecular Imaging, Beijing (China); Liu, Zhenyu; Yang, Xin; Wang, Shuo; Yu, Dongdong [Institute of Automation, CAS Key Laboratory of Molecular Imaging, Beijing (China); Li, Ruili; Li, Hongjun [Beijing YouAn Hospital, Capital Medical University, Department of Radiology, Beijing (China); Cui, Xingwei [Zhengzhou University, Cooperative Innovation Center of Internet Healthcare, Zhengzhou (China); Dong, Enqing [Shandong University, School of Mechanical, Electrical and Information Engineering, Weihai, Shandong Province (China); Tian, Jie [Institute of Automation, CAS Key Laboratory of Molecular Imaging, Beijing (China); University of Chinese Academy of Sciences, Beijing (China)

    2017-10-15

    To identify the white matter (WM) impairments of the antiretroviral therapy (ART)-naive HIV patients by conducting a multivariate pattern analysis (MVPA) of Diffusion Tensor Imaging (DTI) data We enrolled 33 ART-naive HIV patients and 32 Normal controls in the current study. Firstly, the DTI metrics in whole brain WM tracts were extracted for each subject and feed into the Least Absolute Shrinkage and Selection Operators procedure (LASSO)-Logistic regression model to identify the impaired WM tracts. Then, Support Vector Machines (SVM) model was constructed based on the DTI metrics in the impaired WM tracts to make HIV-control group classification. Pearson correlations between the WM impairments and HIV clinical statics were also investigated. Extensive HIV-related impairments were observed in the WM tracts associated with motor function, the corpus callosum (CC) and the frontal WM. With leave-one-out cross validation, accuracy of 83.08% (P=0.002) and the area under the Receiver Operating Characteristic curve of 0.9110 were obtained in the SVM classification model. The impairments of the CC were significantly correlated with the HIV clinic statics. The MVPA was sensitive to detect the HIV-related WM changes. Our findings indicated that the MVPA had considerable potential in exploring the HIV-related WM impairments. (orig.)

  19. Identifying the white matter impairments among ART-naive HIV patients: a multivariate pattern analysis of DTI data

    International Nuclear Information System (INIS)

    Tang, Zhenchao; Liu, Zhenyu; Yang, Xin; Wang, Shuo; Yu, Dongdong; Li, Ruili; Li, Hongjun; Cui, Xingwei; Dong, Enqing; Tian, Jie

    2017-01-01

    To identify the white matter (WM) impairments of the antiretroviral therapy (ART)-naive HIV patients by conducting a multivariate pattern analysis (MVPA) of Diffusion Tensor Imaging (DTI) data We enrolled 33 ART-naive HIV patients and 32 Normal controls in the current study. Firstly, the DTI metrics in whole brain WM tracts were extracted for each subject and feed into the Least Absolute Shrinkage and Selection Operators procedure (LASSO)-Logistic regression model to identify the impaired WM tracts. Then, Support Vector Machines (SVM) model was constructed based on the DTI metrics in the impaired WM tracts to make HIV-control group classification. Pearson correlations between the WM impairments and HIV clinical statics were also investigated. Extensive HIV-related impairments were observed in the WM tracts associated with motor function, the corpus callosum (CC) and the frontal WM. With leave-one-out cross validation, accuracy of 83.08% (P=0.002) and the area under the Receiver Operating Characteristic curve of 0.9110 were obtained in the SVM classification model. The impairments of the CC were significantly correlated with the HIV clinic statics. The MVPA was sensitive to detect the HIV-related WM changes. Our findings indicated that the MVPA had considerable potential in exploring the HIV-related WM impairments. (orig.)

  20. Integrating retrogenesis theory to Alzheimer's disease pathology: insight from DTI-TBSS investigation of the white matter microstructural integrity.

    Science.gov (United States)

    Alves, Gilberto Sousa; Oertel Knöchel, Viola; Knöchel, Christian; Carvalho, André Férrer; Pantel, Johannes; Engelhardt, Eliasz; Laks, Jerson

    2015-01-01

    Microstructural abnormalities in white matter (WM) are often reported in Alzheimer's disease (AD) and may reflect primary or secondary circuitry degeneration (i.e., due to cortical atrophy). The interpretation of diffusion tensor imaging (DTI) eigenvectors, known as multiple indices, may provide new insights into the main pathological models supporting primary or secondary patterns of WM disruption in AD, the retrogenesis, and Wallerian degeneration models, respectively. The aim of this review is to analyze the current literature on the contribution of DTI multiple indices to the understanding of AD neuropathology, taking the retrogenesis model as a reference for discussion. A systematic review using MEDLINE, EMBASE, and PUBMED was performed. Evidence suggests that AD evolves through distinct patterns of WM disruption, in which retrogenesis or, alternatively, the Wallerian degeneration may prevail. Distinct patterns of WM atrophy may be influenced by complex interactions which comprise disease status and progression, fiber localization, concurrent risk factors (i.e., vascular disease, gender), and cognitive reserve. The use of DTI multiple indices in addition to other standard multimodal methods in dementia research may help to determine the contribution of retrogenesis hypothesis to the understanding of neuropathological hallmarks that lead to AD.

  1. Structural brain alterations in bipolar disorder II: a combined voxel-based morphometry (VBM) and diffusion tensor imaging (DTI) study.

    Science.gov (United States)

    Ambrosi, Elisa; Rossi-Espagnet, Maria Camilla; Kotzalidis, Georgios D; Comparelli, Anna; Del Casale, Antonio; Carducci, Filippo; Romano, Andrea; Manfredi, Giovanni; Tatarelli, Roberto; Bozzao, Alessandro; Girardi, Paolo

    2013-09-05

    Brain structural changes have been described in bipolar disorder (BP), but usually studies focused on both I and II subtypes indiscriminately and investigated changes in either brain volume or white matter (WM) integrity. We used combined voxel-based morphometry (VBM) and diffusion tensor imaging (DTI) analysis to track changes in the grey matter (GM) and WM in the brains of patients affected by BPII, as compared to healthy controls. Using VBM and DTI, we scanned 20 DSM-IV-TR BPII patients in their euthymic phase and 21 healthy, age- and gender-matched volunteers with no psychiatric history. VBM showed decreases in GM of BPII patients, compared to controls, which were diffuse in nature and most prominent in the right middle frontal gyrus and in the right superior temporal gurus. DTI showed significant and widespread FA reduction in BPII patients in all major WM tracts, including cortico-cortical association tracts. The small sample size limits the generalisability of our findings. Reduced GM volumes and WM integrity changes in BPII patients are not prominent like those previously reported in bipolar disorder type-I and involve cortical structures and their related association tracts. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Structural brain alterations of Down's syndrome in early childhood evaluation by DTI and volumetric analyses

    Energy Technology Data Exchange (ETDEWEB)

    Gunbey, Hediye Pinar; Bilgici, Meltem Ceyhan; Aslan, Kerim; Incesu, Lutfi [Ondokuz Mayis University, Faculty of Medicine, Department of Radiology, Kurupelit, Samsun (Turkey); Has, Arzu Ceylan [Bilkent University, National Magnetic Resonance Research Center, Ankara (Turkey); Ogur, Methiye Gonul [Ondokuz Mayis University, Department of Genetics, Samsun (Turkey); Alhan, Aslihan [Ufuk University, Department of Statistics, Ankara (Turkey)

    2017-07-15

    To provide an initial assessment of white matter (WM) integrity with diffusion tensor imaging (DTI) and the accompanying volumetric changes in WM and grey matter (GM) through volumetric analyses of young children with Down's syndrome (DS). Ten children with DS and eight healthy control subjects were included in the study. Tract-based spatial statistics (TBSS) were used in the DTI study for whole-brain voxelwise analysis of fractional anisotropy (FA) and mean diffusivity (MD) of WM. Volumetric analyses were performed with an automated segmentation method to obtain regional measurements of cortical volumes. Children with DS showed significantly reduced FA in association tracts of the fronto-temporo-occipital regions as well as the corpus callosum (CC) and anterior limb of the internal capsule (p < 0.05). Volumetric reductions included total cortical GM, cerebellar GM and WM volume, basal ganglia, thalamus, brainstem and CC in DS compared with controls (p < 0.05). These preliminary results suggest that DTI and volumetric analyses may reflect the earliest complementary changes of the neurodevelopmental delay in children with DS and can serve as surrogate biomarkers of the specific elements of WM and GM integrity for cognitive development. (orig.)

  3. Diffusion tensor imaging (DTI) and tractography of the brachial plexus: feasibility and initial experience in neoplastic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, Maria Isabel; Nguyen, Duy; Delavelle, Jacqueline [Geneva University Hospital, Department of Neuroradiology, DISIM, Geneve 14 (Switzerland); Viallon, Magalie [Geneva University Hospital and University of Geneva, Radiology, Geneva (Switzerland); Becker, Minerva [Geneva University Hospital and University of Geneva, Unit of Head and Neck Radiology, Geneva (Switzerland)

    2010-03-15

    The objective of this study was to assess the feasibility and potential clinical applications of diffusion tensor imaging (DTI) and tractography in the normal and pathologic brachial plexus prospectively. Six asymptomatic volunteers and 12 patients with symptoms related to the brachial plexus underwent DTI on a 1.5T system in addition to the routine anatomic plexus imaging protocol. Maps of the apparent diffusion coefficient (ADC) and of fractional anisotropy (FA), as well as tractography of the brachial plexus were obtained. Images were evaluated by two experienced neuroradiologists in a prospective fashion. Three patients underwent surgery, and nine patients underwent conservative medical treatment. Reconstructed DTI (17/18) were of good quality (one case could not be reconstructed due to artifacts). In all volunteers and in 11 patients, the roots and the trunks were clearly delineated with tractography. Mean FA and mean ADC values were as follows: 0.30{+-}0.079 and 1.70{+-}0.35 mm{sup 2}/s in normal fibers, 0.22{+-}0.04 and 1.49{+-}0.49 mm{sup 2}/s in benign neurogenic tumors, and 0.24{+-}0.08 and 1.51{+-}0.52 mm{sup 2}/s in malignant tumors, respectively. Although there was no statistically significant difference in FA and ADC values of normal fibers and fibers at the level of pathology, tractography revealed major differences regarding fiber architecture. In benign neurogenic tumors (n=4), tractography revealed fiber displacement alone (n=2) or fiber displacement and encasement by the tumor (n=2), whereas in the malignant tumors, either fiber disruption/destruction with complete disorganization (n=6) or fiber displacement (n=1) were seen. In patients with fiber displacement alone, surgery confirmed the tractography findings, and excision was successful without sequelae. Our preliminary data suggest that DTI with tractography is feasible in a clinical routine setting. DTI may demonstrate normal tracts, tract displacement, deformation, infiltration, disruption

  4. Diffusion tensor imaging (DTI) and tractography of the brachial plexus: feasibility and initial experience in neoplastic conditions

    International Nuclear Information System (INIS)

    Vargas, Maria Isabel; Nguyen, Duy; Delavelle, Jacqueline; Viallon, Magalie; Becker, Minerva

    2010-01-01

    The objective of this study was to assess the feasibility and potential clinical applications of diffusion tensor imaging (DTI) and tractography in the normal and pathologic brachial plexus prospectively. Six asymptomatic volunteers and 12 patients with symptoms related to the brachial plexus underwent DTI on a 1.5T system in addition to the routine anatomic plexus imaging protocol. Maps of the apparent diffusion coefficient (ADC) and of fractional anisotropy (FA), as well as tractography of the brachial plexus were obtained. Images were evaluated by two experienced neuroradiologists in a prospective fashion. Three patients underwent surgery, and nine patients underwent conservative medical treatment. Reconstructed DTI (17/18) were of good quality (one case could not be reconstructed due to artifacts). In all volunteers and in 11 patients, the roots and the trunks were clearly delineated with tractography. Mean FA and mean ADC values were as follows: 0.30±0.079 and 1.70±0.35 mm 2 /s in normal fibers, 0.22±0.04 and 1.49±0.49 mm 2 /s in benign neurogenic tumors, and 0.24±0.08 and 1.51±0.52 mm 2 /s in malignant tumors, respectively. Although there was no statistically significant difference in FA and ADC values of normal fibers and fibers at the level of pathology, tractography revealed major differences regarding fiber architecture. In benign neurogenic tumors (n=4), tractography revealed fiber displacement alone (n=2) or fiber displacement and encasement by the tumor (n=2), whereas in the malignant tumors, either fiber disruption/destruction with complete disorganization (n=6) or fiber displacement (n=1) were seen. In patients with fiber displacement alone, surgery confirmed the tractography findings, and excision was successful without sequelae. Our preliminary data suggest that DTI with tractography is feasible in a clinical routine setting. DTI may demonstrate normal tracts, tract displacement, deformation, infiltration, disruption, and disorganization of

  5. Harmonizing DTI measurements across scanners to examine the development of white matter microstructure in 803 adolescents of the NCANDA study.

    Science.gov (United States)

    Pohl, Kilian M; Sullivan, Edith V; Rohlfing, Torsten; Chu, Weiwei; Kwon, Dongjin; Nichols, B Nolan; Zhang, Yong; Brown, Sandra A; Tapert, Susan F; Cummins, Kevin; Thompson, Wesley K; Brumback, Ty; Colrain, Ian M; Baker, Fiona C; Prouty, Devin; De Bellis, Michael D; Voyvodic, James T; Clark, Duncan B; Schirda, Claudiu; Nagel, Bonnie J; Pfefferbaum, Adolf

    2016-04-15

    Neurodevelopment continues through adolescence, with notable maturation of white matter tracts comprising regional fiber systems progressing at different rates. To identify factors that could contribute to regional differences in white matter microstructure development, large samples of youth spanning adolescence to young adulthood are essential to parse these factors. Recruitment of adequate samples generally relies on multi-site consortia but comes with the challenge of merging data acquired on different platforms. In the current study, diffusion tensor imaging (DTI) data were acquired on GE and Siemens systems through the National Consortium on Alcohol and NeuroDevelopment in Adolescence (NCANDA), a multi-site study designed to track the trajectories of regional brain development during a time of high risk for initiating alcohol consumption. This cross-sectional analysis reports baseline Tract-Based Spatial Statistic (TBSS) of regional fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (L1), and radial diffusivity (LT) from the five consortium sites on 671 adolescents who met no/low alcohol or drug consumption criteria and 132 adolescents with a history of exceeding consumption criteria. Harmonization of DTI metrics across manufacturers entailed the use of human-phantom data, acquired multiple times on each of three non-NCANDA participants at each site's MR system, to determine a manufacturer-specific correction factor. Application of the correction factor derived from human phantom data measured on MR systems from different manufacturers reduced the standard deviation of the DTI metrics for FA by almost a half, enabling harmonization of data that would have otherwise carried systematic error. Permutation testing supported the hypothesis of higher FA and lower diffusivity measures in older adolescents and indicated that, overall, the FA, MD, and L1 of the boys were higher than those of the girls, suggesting continued microstructural development

  6. An approach to next step device optimisation

    International Nuclear Information System (INIS)

    Salpietro, E.

    2000-01-01

    The requirements for ITER EDA were to achieve ignition with a good safety margin, and controlled long inductive burn. These requirements lead to a big device, which requested a too ambitious step to be undertaken by the world fusion community. More realistic objectives for a next step device shall be to demonstrate the net production of energy with a high energy gain factor (Q) and a high boot strap current fraction (>60%) which is required for a Fusion Power Plant (FPP). The Next Step Device (NSD) shall also allow operation flexibility in order to explore a large range of plasma parameters to find out the optimum concept for the fusion power plant prototype. These requirements could be too demanding for one single device and could probably be better explored in a strongly integrated world programme. The cost of one or more devices is the decisive factor for the choice of the fusion power development programme strategy. The plasma elongation and triangularity have a strong impact in the cost of the device and are limited by the plasma vertical position control issue. The distance between plasma separatrix and the toroidal field conductor does not vary a lot between devices. It is determined by the sum of the distance between first wall-plasma sepratrix and the thickness of the nuclear shield required to protect the toroidal field coil insultation. The thickness of the TF coil is determined by the allowable stresses and superconducting characteristics. The outer radius of the central solenoid is the result of an optimisation to provide the magnetic flux to inductively drive the plasma. Therefore, in order to achieve the objectives for Q and boot-strap current fractions at the minimum cost, the plasma aspect ratio and magnetic field value shall be determined. The paper will present the critical issues for the next device and will make considerations on the optimal way to proceed towards the realisation of the fusion power plant

  7. Optimisation of material discrimination using spectral CT

    International Nuclear Information System (INIS)

    Nik, S.J.; Meyer, J.; Watts, R.

    2010-01-01

    Full text: Spectral computed tomography (CT) using novel X-ray photon counting detectors (PCDs) with energy resolving capabilities is capable of providing energy-selective images. This extra energy information may allow materials such as iodine and calcium, or water and fat to be distinguished. PCDs have energy thresholds, enabling the classification of photons into multiple energy bins. The inform tion content of spectral CT images depends on how the photons are grouped together. [n this work, a method is presented to optimise energy windows for maximum material discrimination. Given a combination of thicknesses, the reference number of expected photons in each energy bin is computed using the Bee Lambert equation. A similar calculation is performed for an exhaustive range of thicknesses and the number of photons in each case is com pared to the reference, allowing a statistical map of the uncertainty in thickness parameters to be constructed. The 63%-confidence region in the two-dimensional thickness space is a representation of how optimal the bins are for material separation. The model is demonstrated with 0.1 mm of iodine and 2.2 mm of calcium using two adjacent bins encompassing the entire energy range. Bins bordering at the iodine k-edge of 33.2 keY are found to be optimal. When compared to two abutted energy bins with equal incident counts as used in the literature (bordering at 54 keY), the thickness uncertainties are reduced from approximately 4% to less than I % (see Figure). This approach has been developed for two materials and is expandable to an arbitrary number of materials and bins.

  8. Optimisation of Investment Resources at Small Enterprises

    Directory of Open Access Journals (Sweden)

    Shvets Iryna B.

    2014-03-01

    Full Text Available The goal of the article lies in the study of the process of optimisation of the structure of investment resources, development of criteria and stages of optimisation of volumes of investment resources for small enterprises by types of economic activity. The article characterises the process of transformation of investment resources into assets and liabilities of the balances of small enterprises and conducts calculation of the structure of sources of formation of investment resources in Ukraine at small enterprises by types of economic activity in 2011. On the basis of the conducted analysis of the structure of investment resources of small enterprises the article forms main groups of criteria of optimisation in the context of individual small enterprises by types of economic activity. The article offers an algorithm and step-by-step scheme of optimisation of investment resources at small enterprises in the form of a multi-stage process of management of investment resources in the context of increase of their mobility and rate of transformation of existing resources into investments. The prospect of further studies in this direction is development of a structural and logic scheme of optimisation of volumes of investment resources at small enterprises.

  9. Optimisation of warpage on thin shell plastic part using response surface methodology (RSM) and glowworm swarm optimisation (GSO)

    Science.gov (United States)

    Asyirah, B. N.; Shayfull, Z.; Nasir, S. M.; Fathullah, M.; Hazwan, M. H. M.

    2017-09-01

    In manufacturing a variety of parts, plastic injection moulding is widely use. The injection moulding process parameters have played important role that affects the product's quality and productivity. There are many approaches in minimising the warpage ans shrinkage such as artificial neural network, genetic algorithm, glowworm swarm optimisation and hybrid approaches are addressed. In this paper, a systematic methodology for determining a warpage and shrinkage in injection moulding process especially in thin shell plastic parts are presented. To identify the effects of the machining parameters on the warpage and shrinkage value, response surface methodology is applied. In thos study, a part of electronic night lamp are chosen as the model. Firstly, experimental design were used to determine the injection parameters on warpage for different thickness value. The software used to analyse the warpage is Autodesk Moldflow Insight (AMI) 2012.

  10. Optimisation of logistics processes of energy grass collection

    Science.gov (United States)

    Bányai, Tamás.

    2010-05-01

    The collection of energy grass is a logistics-intensive process [1]. The optimal design and control of transportation and collection subprocesses is a critical point of the supply chain. To avoid irresponsible decisions by right of experience and intuition, the optimisation and analysis of collection processes based on mathematical models and methods is the scientific suggestible way. Within the frame of this work, the author focuses on the optimisation possibilities of the collection processes, especially from the point of view transportation and related warehousing operations. However the developed optimisation methods in the literature [2] take into account the harvesting processes, county-specific yields, transportation distances, erosion constraints, machinery specifications, and other key variables, but the possibility of more collection points and the multi-level collection were not taken into consideration. The possible areas of using energy grass is very wide (energetically use, biogas and bio alcohol production, paper and textile industry, industrial fibre material, foddering purposes, biological soil protection [3], etc.), so not only a single level but also a multi-level collection system with more collection and production facilities has to be taken into consideration. The input parameters of the optimisation problem are the followings: total amount of energy grass to be harvested in each region; specific facility costs of collection, warehousing and production units; specific costs of transportation resources; pre-scheduling of harvesting process; specific transportation and warehousing costs; pre-scheduling of processing of energy grass at each facility (exclusive warehousing). The model take into consideration the following assumptions: (1) cooperative relation among processing and production facilties, (2) capacity constraints are not ignored, (3) the cost function of transportation is non-linear, (4) the drivers conditions are ignored. The

  11. Multicriteria Optimisation in Logistics Forwarder Activities

    Directory of Open Access Journals (Sweden)

    Tanja Poletan Jugović

    2007-05-01

    Full Text Available Logistics forwarder, as organizer and planner of coordinationand integration of all the transport and logistics chains elements,uses adequate ways and methods in the process of planningand decision-making. One of these methods, analysed inthis paper, which could be used in optimisation of transportand logistics processes and activities of logistics forwarder, isthe multicriteria optimisation method. Using that method, inthis paper is suggested model of multicriteria optimisation of logisticsforwarder activities. The suggested model of optimisationis justified in keeping with method principles of multicriteriaoptimization, which is included in operation researchmethods and it represents the process of multicriteria optimizationof variants. Among many different processes of multicriteriaoptimization, PROMETHEE (Preference Ranking OrganizationMethod for Enrichment Evaluations and Promcalc& Gaia V. 3.2., computer program of multicriteria programming,which is based on the mentioned process, were used.

  12. Noise aspects at aerodynamic blade optimisation projects

    International Nuclear Information System (INIS)

    Schepers, J.G.

    1997-06-01

    The Netherlands Energy Research Foundation (ECN) has often been involved in industrial projects, in which blade geometries are created automatic by means of numerical optimisation. Usually, these projects aim at the determination of the aerodynamic optimal wind turbine blade, i.e. the goal is to design a blade which is optimal with regard to energy yield. In other cases, blades have been designed which are optimal with regard to cost of generated energy. However, it is obvious that the wind turbine blade designs which result from these optimisations, are not necessarily optimal with regard to noise emission. In this paper an example is shown of an aerodynamic blade optimisation, using the ECN-program PVOPT. PVOPT calculates the optimal wind turbine blade geometry such that the maximum energy yield is obtained. Using the aerodynamic optimal blade design as a basis, the possibilities of noise reduction are investigated. 11 figs., 8 refs

  13. Analysis of the diffusion tensor imaging parameters of a normal cervical spinal cord in a healthy population.

    Science.gov (United States)

    Wei, Liang-Feng; Wang, Shou-Sen; Zheng, Zhao-Cong; Tian, Jun; Xue, Liang

    2017-05-01

    Diffusion tensor imaging (DTI) shows great advantage in the diagnosis of brain diseases, including cervical spinal cord (CSC) disease. This study aims to obtain the normal values of the DTI parameters for a healthy population and to establish a baseline for CSC disease diagnosis using DTI. A total of 36 healthy adults were subjected to magnetic resonance imaging (MRI) for the entire CSC using the Siemens 3.0 T MR System. Sagittal DTI acquisition was carried out with a single-shot spin-echo echo-planar imaging (EPI) sequence along 12 non-collinear directions. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were determined at different cervical levels using a region of interest (ROI) method, following which they were correlated with parameters, like age and sex. Further, diffusion tensor tracking (DTT) was carried out to reconstruct the white matter fiber bundles of the CSC. The full and complete fiber bundle structure of a normal CSC was confirmed in both the T2-weighted and DTI images. The FA and ADC values were significantly negatively correlated with each other and showed strongly negative and positive correlations with age, respectively, but not with sex. Additionally, there was no significant difference between the FA and the ADC values at different cervical levels. The DTI technique can act as an important supplement to the conventional MRI technique for CSC observation. Moreover, the FA and ADC values can be used as sensitive parameters in the DTI study on the CSC by taking the effects of age into consideration.

  14. Topology Optimisation of Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Thike Aye Min

    2016-01-01

    Full Text Available Wireless sensor networks are widely used in a variety of fields including industrial environments. In case of a clustered network the location of cluster head affects the reliability of the network operation. Finding of the optimum location of the cluster head, therefore, is critical for the design of a network. This paper discusses the optimisation approach, based on the brute force algorithm, in the context of topology optimisation of a cluster structure centralised wireless sensor network. Two examples are given to verify the approach that demonstrate the implementation of the brute force algorithm to find an optimum location of the cluster head.

  15. The optimisation of a water distribution system using Bentley WaterGEMS software

    Directory of Open Access Journals (Sweden)

    Świtnicka Karolina

    2017-01-01

    Full Text Available The proper maintenance of water distribution systems (WDSs requires from operators multiple actions in order to ensure optimal functioning. Usually, all requirements should be adjusted simultaneously. Therefore, the decision-making process is often supported by multi-criteria optimisation methods. Significant improvements of exploitation conditions of WDSs functioning can be achieved by connecting small water supply networks into group systems. Among many potential tools supporting advanced maintenance and management of WDSs, significant improvements have tools that can find the optimal solution by the implemented mechanism of metaheuristic methods, such as the genetic algorithm. In this paper, an exemplary WDS functioning optimisation is presented, in relevance to a group water supply system. The action range of optimised parameters included: maximisation of water flow velocity, regulation of pressure head, minimisation of water retention time in a network (water age and minimisation of pump energy consumption. All simulations were performed in Bentley WaterGEMS software.

  16. Balanced the Trade-offs problem of ANFIS Using Particle Swarm Optimisation

    Directory of Open Access Journals (Sweden)

    Dian Palupi Rini

    2013-11-01

    Full Text Available Improving the approximation accuracy and interpretability of fuzzy systems is an important issue either in fuzzy systems theory or in its applications . It is known that simultaneous optimisation both issues was the trade-offs problem, but it will improve performance of the system and avoid overtraining of data. Particle swarm optimisation (PSO is part of evolutionary algorithm that is good candidate algorithms to solve multiple optimal solution and better global search space. This paper introduces an integration of PSO dan ANFIS for optimise its learning especially for tuning membership function parameters and finding the optimal rule for better classification. The proposed method has been tested on four standard dataset from UCI machine learning i.e. Iris Flower, Habermans Survival Data, Balloon and Thyroid dataset. The results have shown better classification using the proposed PSO-ANFIS and the time complexity has reduced accordingly.

  17. Optimisation of electrical system for offshore wind farms via genetic algorithm

    DEFF Research Database (Denmark)

    Chen, Zhe; Zhao, Menghua; Blaabjerg, Frede

    2009-01-01

    An optimisation platform based on genetic algorithm (GA) is presented, where the main components of a wind farm and key technical specifications are used as input parameters and the electrical system design of the wind farm is optimised in terms of both production cost and system reliability....... The power losses, wind power production, initial investment and maintenance costs are considered in the production cost. The availability of components and network redundancy are included in the reliability evaluation. The method of coding an electrical system to a binary string, which is processed by GA......, is developed. Different GA techniques are investigated based on a real example offshore wind farm. This optimisation platform has been demonstrated as a powerful tool for offshore wind farm design and evaluation....

  18. Use of artificial intelligence techniques for optimisation of co-combustion of coal with biomass

    Energy Technology Data Exchange (ETDEWEB)

    Tan, C.K.; Wilcox, S.J.; Ward, J. [University of Glamorgan, Pontypridd (United Kingdom). Division of Mechanical Engineering

    2006-03-15

    The optimisation of burner operation in conventional pulverised-coal-fired boilers for co-combustion applications represents a significant challenge This paper describes a strategic framework in which Artificial Intelligence (AI) techniques can be applied to solve such an optimisation problem. The effectiveness of the proposed system is demonstrated by a case study that simulates the co-combustion of coal with sewage sludge in a 500-kW pilot-scale combustion rig equipped with a swirl stabilised low-NOx burner. A series of Computational Fluid Dynamics (CFD) simulations were performed to generate data for different operating conditions, which were then used to train several Artificial Neural Networks (ANNs) to predict the co-combustion performance. Once trained, the ANNs were able to make estimations of unseen situations in a fraction of the time taken by the CFD simulation. Consequently, the networks were capable of representing the underlying physics of the CFD models and could be executed efficiently for a large number of iterations as required by optimisation techniques based on Evolutionary Algorithms (EAs). Four operating parameters of the burner, namely the swirl angles and flow rates of the secondary and tertiary combustion air were optimised with the objective of minimising the NOx and CO emissions as well as the unburned carbon at the furnace exit. The results suggest that ANNs combined with EAs provide a useful tool for optimising co-combustion processes.

  19. Satellite Vibration Testing: Angle optimisation method to Reduce Overtesting

    Science.gov (United States)

    Knight, Charly; Remedia, Marcello; Aglietti, Guglielmo S.; Richardson, Guy

    2018-06-01

    Spacecraft overtesting is a long running problem, and the main focus of most attempts to reduce it has been to adjust the base vibration input (i.e. notching). Instead this paper examines testing alternatives for secondary structures (equipment) coupled to the main structure (satellite) when they are tested separately. Even if the vibration source is applied along one of the orthogonal axes at the base of the coupled system (satellite plus equipment), the dynamics of the system and potentially the interface configuration mean the vibration at the interface may not occur all along one axis much less the corresponding orthogonal axis of the base excitation. This paper proposes an alternative testing methodology in which the testing of a piece of equipment occurs at an offset angle. This Angle Optimisation method may have multiple tests but each with an altered input direction allowing for the best match between all specified equipment system responses with coupled system tests. An optimisation process that compares the calculated equipment RMS values for a range of inputs with the maximum coupled system RMS values, and is used to find the optimal testing configuration for the given parameters. A case study was performed to find the best testing angles to match the acceleration responses of the centre of mass and sum of interface forces for all three axes, as well as the von Mises stress for an element by a fastening point. The angle optimisation method resulted in RMS values and PSD responses that were much closer to the coupled system when compared with traditional testing. The optimum testing configuration resulted in an overall average error significantly smaller than the traditional method. Crucially, this case study shows that the optimum test campaign could be a single equipment level test opposed to the traditional three orthogonal direction tests.

  20. Friction stir welding: multi-response optimisation using Taguchi-based GRA

    Directory of Open Access Journals (Sweden)

    Jitender Kundu

    2016-01-01

    Full Text Available In present experimental work, friction stir welding of aluminium alloy 5083- H321 is performed for optimisation of process parameters for maximum tensile strength. Taguchi’s L9 orthogonal array has been used for three parameters – tool rotational speed (TRS, traverse speed (TS, and tool tilt angle (TTA with three levels. Multi-response optimisation has been carried out through Taguchi-based grey relational analysis. The grey relational grade has been calculated for all three responses – ultimate tensile strength, percentage elongation, and micro-hardness. Analysis of variance is the tool used for obtaining grey relational grade to find out the significant process parameters. TRS and TS are the two most significant parameters which influence most of the quality characteristics of friction stir welded joint. Validation of predicted values done through confirmation experiments at optimum setting shows a good agreement with experimental values.

  1. Application of Surpac and Whittle Software in Open Pit Optimisation ...

    African Journals Online (AJOL)

    Application of Surpac and Whittle Software in Open Pit Optimisation and Design. ... This paper studies the Surpac and Whittle software and their application in designing an optimised pit. ... EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

  2. (MBO) algorithm in multi-reservoir system optimisation

    African Journals Online (AJOL)

    A comparative study of marriage in honey bees optimisation (MBO) algorithm in ... A practical application of the marriage in honey bees optimisation (MBO) ... to those of other evolutionary algorithms, such as the genetic algorithm (GA), ant ...

  3. A Unified Approach to Diffusion Direction Sensitive Slice Registration and 3-D DTI Reconstruction From Moving Fetal Brain Anatomy

    DEFF Research Database (Denmark)

    Hansen, Mads Fogtmann; Seshamani, Sharmishtaa; Kroenke, Christopher

    2014-01-01

    to the underlying anatomy. Previous image registration techniques have been described to estimate the between slice fetal head motion, allowing the reconstruction of 3D a diffusion estimate on a regular grid using interpolation. We propose Approach to Unified Diffusion Sensitive Slice Alignment and Reconstruction...... (AUDiSSAR) that explicitly formulates a process for diffusion direction sensitive DW-slice-to-DTI-volume alignment. This also incorporates image resolution modeling to iteratively deconvolve the effects of the imaging point spread function using the multiple views provided by thick slices acquired...

  4. Extending Particle Swarm Optimisers with Self-Organized Criticality

    DEFF Research Database (Denmark)

    Løvbjerg, Morten; Krink, Thiemo

    2002-01-01

    Particle swarm optimisers (PSOs) show potential in function optimisation, but still have room for improvement. Self-organized criticality (SOC) can help control the PSO and add diversity. Extending the PSO with SOC seems promising reaching faster convergence and better solutions.......Particle swarm optimisers (PSOs) show potential in function optimisation, but still have room for improvement. Self-organized criticality (SOC) can help control the PSO and add diversity. Extending the PSO with SOC seems promising reaching faster convergence and better solutions....

  5. Operational Radiological Protection and Aspects of Optimisation

    International Nuclear Information System (INIS)

    Lazo, E.; Lindvall, C.G.

    2005-01-01

    Since 1992, the Nuclear Energy Agency (NEA), along with the International Atomic Energy Agency (IAEA), has sponsored the Information System on Occupational Exposure (ISOE). ISOE collects and analyses occupational exposure data and experience from over 400 nuclear power plants around the world and is a forum for radiological protection experts from both nuclear power plants and regulatory authorities to share lessons learned and best practices in the management of worker radiation exposures. In connection to the ongoing work of the International Commission on Radiological Protection (ICRP) to develop new recommendations, the ISOE programme has been interested in how the new recommendations would affect operational radiological protection application at nuclear power plants. Bearing in mind that the ICRP is developing, in addition to new general recommendations, a new recommendation specifically on optimisation, the ISOE programme created a working group to study the operational aspects of optimisation, and to identify the key factors in optimisation that could usefully be reflected in ICRP recommendations. In addition, the Group identified areas where further ICRP clarification and guidance would be of assistance to practitioners, both at the plant and the regulatory authority. The specific objective of this ISOE work was to provide operational radiological protection input, based on practical experience, to the development of new ICRP recommendations, particularly in the area of optimisation. This will help assure that new recommendations will best serve the needs of those implementing radiation protection standards, for the public and for workers, at both national and international levels. (author)

  6. Optimisation of surgical care for rectal cancer

    NARCIS (Netherlands)

    Borstlap, W.A.A.

    2017-01-01

    Optimisation of surgical care means weighing the risk of treatment related morbidity against the patients’ potential benefits of a surgical intervention. The first part of this thesis focusses on the anaemic patient undergoing colorectal surgery. Hypothesizing that a more profound haemoglobin

  7. On optimal development and becoming an optimiser

    NARCIS (Netherlands)

    de Ruyter, D.J.

    2012-01-01

    The article aims to provide a justification for the claim that optimal development and becoming an optimiser are educational ideals that parents should pursue in raising their children. Optimal development is conceptualised as enabling children to grow into flourishing persons, that is persons who

  8. Particle Swarm Optimisation with Spatial Particle Extension

    DEFF Research Database (Denmark)

    Krink, Thiemo; Vesterstrøm, Jakob Svaneborg; Riget, Jacques

    2002-01-01

    In this paper, we introduce spatial extension to particles in the PSO model in order to overcome premature convergence in iterative optimisation. The standard PSO and the new model (SEPSO) are compared w.r.t. performance on well-studied benchmark problems. We show that the SEPSO indeed managed...

  9. OPTIMISATION OF COMPRESSIVE STRENGTH OF PERIWINKLE ...

    African Journals Online (AJOL)

    In this paper, a regression model is developed to predict and optimise the compressive strength of periwinkle shell aggregate concrete using Scheffe's regression theory. The results obtained from the derived regression model agreed favourably with the experimental data. The model was tested for adequacy using a student ...

  10. An efficient optimisation method in groundwater resource ...

    African Journals Online (AJOL)

    DRINIE

    2003-10-04

    Oct 4, 2003 ... theories developed in the field of stochastic subsurface hydrology. In reality, many ... Recently, some researchers have applied the multi-stage ... Then a robust solution of the optimisation problem given by Eqs. (1) to (3) is as ...

  11. Water distribution systems design optimisation using metaheuristics ...

    African Journals Online (AJOL)

    The topic of multi-objective water distribution systems (WDS) design optimisation using metaheuristics is investigated, comparing numerous modern metaheuristics, including several multi-objective evolutionary algorithms, an estimation of distribution algorithm and a recent hyperheuristic named AMALGAM (an evolutionary ...

  12. Optimisation of efficiency of axial fans

    NARCIS (Netherlands)

    Kruyt, Nicolaas P.; Pennings, P.C.; Faasen, R.

    2014-01-01

    A three-stage research project has been executed to develop ducted axial-fans with increased efficiency. In the first stage a design method has been developed in which various conflicting design criteria can be incorporated. Based on this design method, an optimised design has been determined

  13. Thermodynamic optimisation of a heat exchanger

    NARCIS (Netherlands)

    Cornelissen, Rene; Hirs, Gerard

    1999-01-01

    The objective of this paper is to show that for the optimal design of an energy system, where there is a trade-off between exergy saving during operation and exergy use during construction of the energy system, exergy analysis and life cycle analysis should be combined. An exergy optimisation of a

  14. Self-optimising control of sewer systems

    DEFF Research Database (Denmark)

    Mauricio Iglesias, Miguel; Montero-Castro, Ignacio; Mollerup, Ane Loft

    2013-01-01

    . The definition of an optimal performance was carried out by through a two-stage optimisation (stochastic and deterministic) to take into account both the overflow during the current rain event as well as the expected overflow, given the probability of a future rain event. The methodology is successfully applied...

  15. Optimising Shovel-Truck Fuel Consumption using Stochastic ...

    African Journals Online (AJOL)

    Optimising the fuel consumption and truck waiting time can result in significant fuel savings. The paper demonstrates that stochastic simulation is an effective tool for optimising the utilisation of fossil-based fuels in mining and related industries. Keywords: Stochastic, Simulation Modelling, Mining, Optimisation, Shovel-Truck ...

  16. Design of optimised backstepping controller for the synchronisation ...

    Indian Academy of Sciences (India)

    Ehsan Fouladi

    2017-12-18

    Dec 18, 2017 ... for the proposed optimised method compared to PSO optimised controller or any non-optimised backstepping controller. Keywords. Colpitts oscillator; backstepping controller; chaos synchronisation; shark smell algorithm; particle .... The velocity model is based on the gradient of the objective function, tilting ...

  17. Efficient topology optimisation of multiscale and multiphysics problems

    DEFF Research Database (Denmark)

    Alexandersen, Joe

    The aim of this Thesis is to present efficient methods for optimising high-resolution problems of a multiscale and multiphysics nature. The Thesis consists of two parts: one treating topology optimisation of microstructural details and the other treating topology optimisation of conjugate heat...

  18. Age-related changes of the diffusion tensor imaging parameters of the normal cervical spinal cord

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Kun, E-mail: medsciwangkun@126.com [Orthopedics Department, Changhai Hospital Affiliated to Second Military Medical University, Shanghai (China); Song, Qingxin; Zhang, Fan; Chen, Zhi; Hou, Canglong; Tang, Yixing [Orthopedics Department, Changhai Hospital Affiliated to Second Military Medical University, Shanghai (China); Chen, Shiyue [Radiology Department, Changhai Hospital Affiliated to Second Military Medical University, Shanghai (China); Hao, Qiang, E-mail: haoqiang@189.cn [Radiology Department, Changhai Hospital Affiliated to Second Military Medical University, Shanghai (China); Shen, Hongxing, E-mail: shenhxgk@126.com [Orthopedics Department, Changhai Hospital Affiliated to Second Military Medical University, Shanghai (China)

    2014-12-15

    Highlights: • It is essential to determine the DTI parameters in the whole CSC. • To analyze DTI parameters in all intervertebral space levels of the CSC. • To study the impact of age on these parameters in healthy Chinese subjects. • Provide better insights in factors that could bias the diagnosis of CSC pathologies. - Abstract: Background: The diffusion tensor imaging (DTI) parameters of the cervical spinal cord (CSC) changes with age. However, previous studies only examined specific CSC areas. Objectives: To analyze the DTI parameters in all intervertebral space levels of the whole normal CSC and to study the impact of age on these parameters in a Chinese population. Methods: Thirty-six healthy subjects aged 20–77 years were recruited. DTI parameters were calculated for gray matter (GM) and white matter (WM) funiculi in all the CSC intervertebral spaces (C1/2-C6/7). Age-related changes of DTI parameters were analyzed for the GM and WM funiculi. Results: Fractional anisotropy (FA) and mean diffusivity (MD) were lower in GM than in WM. MD and FA values were lower in the WM in the lower CSC compared with the upper CSC (all P < 0.05), but no difference was observed in GM. In ventral funiculi, MD increased with age, while FA decreased (all P < 0.001). In lateral and dorsal funiculi, MD and FA decreased with age (all P < 0.001). In GM, MD and FA decreased with age (all P < 0.001). Significant age-related changes were observed in FA and MD from GM and WM funiculi. FA was correlated with age in all funiculi (ventral: r = −0.733; lateral: r = −0.468; dorsal: r = −0.607; GM: r = −0.724; all P < 0.01). Conclusion: Important changes in MD and FA were observed with advancing age at all levels of CSC in Chinese patients. DTI parameters may be useful to assess CSC pathology, but the influence of age and segments need to be taken into account in diagnosis.

  19. Age-related changes of the diffusion tensor imaging parameters of the normal cervical spinal cord

    International Nuclear Information System (INIS)

    Wang, Kun; Song, Qingxin; Zhang, Fan; Chen, Zhi; Hou, Canglong; Tang, Yixing; Chen, Shiyue; Hao, Qiang; Shen, Hongxing

    2014-01-01

    Highlights: • It is essential to determine the DTI parameters in the whole CSC. • To analyze DTI parameters in all intervertebral space levels of the CSC. • To study the impact of age on these parameters in healthy Chinese subjects. • Provide better insights in factors that could bias the diagnosis of CSC pathologies. - Abstract: Background: The diffusion tensor imaging (DTI) parameters of the cervical spinal cord (CSC) changes with age. However, previous studies only examined specific CSC areas. Objectives: To analyze the DTI parameters in all intervertebral space levels of the whole normal CSC and to study the impact of age on these parameters in a Chinese population. Methods: Thirty-six healthy subjects aged 20–77 years were recruited. DTI parameters were calculated for gray matter (GM) and white matter (WM) funiculi in all the CSC intervertebral spaces (C1/2-C6/7). Age-related changes of DTI parameters were analyzed for the GM and WM funiculi. Results: Fractional anisotropy (FA) and mean diffusivity (MD) were lower in GM than in WM. MD and FA values were lower in the WM in the lower CSC compared with the upper CSC (all P < 0.05), but no difference was observed in GM. In ventral funiculi, MD increased with age, while FA decreased (all P < 0.001). In lateral and dorsal funiculi, MD and FA decreased with age (all P < 0.001). In GM, MD and FA decreased with age (all P < 0.001). Significant age-related changes were observed in FA and MD from GM and WM funiculi. FA was correlated with age in all funiculi (ventral: r = −0.733; lateral: r = −0.468; dorsal: r = −0.607; GM: r = −0.724; all P < 0.01). Conclusion: Important changes in MD and FA were observed with advancing age at all levels of CSC in Chinese patients. DTI parameters may be useful to assess CSC pathology, but the influence of age and segments need to be taken into account in diagnosis

  20. Infrastructure optimisation via MBR retrofit: a design guide.

    Science.gov (United States)

    Bagg, W K

    2009-01-01

    Wastewater management is continually evolving with the development and implementation of new, more efficient technologies. One of these is the Membrane Bioreactor (MBR). Although a relatively new technology in Australia, MBR wastewater treatment has been widely used elsewhere for over 20 years, with thousands of MBRs now in operation worldwide. Over the past 5 years, MBR technology has been enthusiastically embraced in Australia as a potential treatment upgrade option, and via retrofit typically offers two major benefits: (1) more capacity using mostly existing facilities, and (2) very high quality treated effluent. However, infrastructure optimisation via MBR retrofit is not a simple or low-cost solution and there are many factors which should be carefully evaluated before deciding on this method of plant upgrade. The paper reviews a range of design parameters which should be carefully evaluated when considering an MBR retrofit solution. Several actual and conceptual case studies are considered to demonstrate both advantages and disadvantages. Whilst optimising existing facilities and production of high quality water for reuse are powerful drivers, it is suggested that MBRs are perhaps not always the most sustainable Whole-of-Life solution for a wastewater treatment plant upgrade, especially by way of a retrofit.

  1. Optimisation Methods for Cam Mechanisms

    Directory of Open Access Journals (Sweden)

    Claudia–Mari Popa

    2010-01-01

    Full Text Available In this paper we present the criteria which represent the base of optimizing the cam mechanisms and also we perform the calculations for several types of mechanisms. We study the influence of the constructive parameters in case of the simple machines with rotation cam and follower (flat or curve of translation on the curvature radius and that of the transmission angle. As it follows, we present the optimization calculations of the cam and flat rotation follower mechanisms, as well as the calculations for optimizing the cam mechanisms by circular groove followers’ help. For an easier interpretation of the results, we have visualized the obtained cam in AutoCAD according to the script files generated by a calculation program.

  2. Cerebral metabolic and structural alterations in hereditary spastic paraplegia with thin corpus callosum assessed by MRS and DTI

    International Nuclear Information System (INIS)

    Dreha-Kulaczewski, Steffi; Dechent, Peter; Helms, Gunther; Frahm, Jens; Gaertner, Jutta; Brockmann, Knut

    2006-01-01

    Hereditary spastic paraplegia with thin corpus callosum (HSP-TCC) is a complicated form of autosomal-recessive hereditary spastic paraplegia. Characteristic clinical features comprise progressive spastic gait, cognitive impairment, and ataxia. Diagnostic MRI findings include thinning of the corpus callosum and non-progressive white matter (WM) alterations. To study the extent of axonal involvement, we performed localized proton magnetic resonance spectroscopy (MRS) of the cerebral WM and cortical grey matter (GM) in a patient with HSP-TCC at 20 and 25 years of age. The second investigation included diffusion tensor imaging (DTI). While MRS of the GM was normal, affected WM was characterized by major metabolic alterations such as reduced concentrations of N-acetylaspartate and N-acetylaspartyl-glutamate, creatine and phosphocreatine, and choline-containing compounds as well as elevated levels of myo-inositol. These abnormalities showed progression over a period of 5 years. DTI revealed increased mean diffusivity as well as reduced fractional anisotropy in periventricular WM. The metabolic and structural findings are consistent with progressive neuroaxonal loss in the WM accompanied by astrocytic proliferation - histopathological changes known to occur in HSP-TCC. Our results are in agreement with the hypothesis that the primary pathological process in HSP-TCC affects the axon, possibly due to impaired axonal trafficking. (orig.)

  3. Cerebral asymmetry in patients with schizophrenia: a voxel-based morphometry (VBM) and diffusion tensor imaging (DTI) study.

    Science.gov (United States)

    Takao, Hidemasa; Abe, Osamu; Yamasue, Hidenori; Aoki, Shigeki; Kasai, Kiyoto; Ohtomo, Kuni

    2010-01-01

    To evaluate the differences in gray- and white-matter asymmetry between schizophrenia patients and normal subjects. Forty-eight right-handed patients with chronic schizophrenia (24 males and 24 females) and 48 right-handed age- and sex-matched healthy controls (24 males and 24 females) were included in this study. The effects of diagnosis on gray-matter volume asymmetry and white-matter fractional anisotropy (FA) asymmetry were evaluated with use of voxel-based morphometry (VBM) and voxel-based analysis of FA maps derived from diffusion tensor imaging (DTI), respectively. The mean gray- and white-matter volumes were significantly smaller in the schizophrenia group than in the control group. The voxel-based morphometry (VBM) showed no significant effect of diagnosis on gray-matter volume asymmetry. The voxel-based analysis of DTI also showed no significant effect of diagnosis on white-matter FA asymmetry. Our results of voxel-based analyses showed no significant differences in either gray-matter volume asymmetry or white-matter FA asymmetry between schizophrenia patients and normal subjects. (c) 2009 Wiley-Liss, Inc.

  4. A T1 and DTI fused 3D corpus callosum analysis in pre- vs. post-season contact sports players

    Science.gov (United States)

    Lao, Yi; Law, Meng; Shi, Jie; Gajawelli, Niharika; Haas, Lauren; Wang, Yalin; Leporé, Natasha

    2015-01-01

    Sports related traumatic brain injury (TBI) is a worldwide public health issue, and damage to the corpus callosum (CC) has been considered as an important indicator of TBI. However, contact sports players suffer repeated hits to the head during the course of a season even in the absence of diagnosed concussion, and less is known about their effect on callosal anatomy. In addition, T1-weighted and diffusion tensor brain magnetic resonance images (DTI) have been analyzed separately, but a joint analysis of both types of data may increase statistical power and give a more complete understanding of anatomical correlates of subclinical concussions in these athletes. Here, for the first time, we fuse T1 surface-based morphometry and a new DTI analysis on 3D surface representations of the CCs into a single statistical analysis on these subjects. Our new combined method successfully increases detection power in detecting differences between pre- vs. post-season contact sports players. Alterations are found in the ventral genu, isthmus, and splenium of CC. Our findings may inform future health assessments in contact sports players. The new method here is also the first truly multimodal diffusion and T1-weighted analysis of the CC, and may be useful to detect anatomical changes in the corpus callosum in other multimodal datasets.

  5. Multilevel Deficiency of White Matter Connectivity Networks in Alzheimer's Disease: A Diffusion MRI Study with DTI and HARDI Models.

    Science.gov (United States)

    Wang, Tao; Shi, Feng; Jin, Yan; Yap, Pew-Thian; Wee, Chong-Yaw; Zhang, Jianye; Yang, Cece; Li, Xia; Xiao, Shifu; Shen, Dinggang

    2016-01-01

    Alzheimer's disease (AD) is the most common form of dementia in elderly people. It is an irreversible and progressive brain disease. In this paper, we utilized diffusion-weighted imaging (DWI) to detect abnormal topological organization of white matter (WM) structural networks. We compared the differences between WM connectivity characteristics at global, regional, and local levels in 26 patients with probable AD and 16 normal control (NC) elderly subjects, using connectivity networks constructed with the diffusion tensor imaging (DTI) model and the high angular resolution diffusion imaging (HARDI) model, respectively. At the global level, we found that the WM structural networks of both AD and NC groups had a small-world topology; however, the AD group showed a significant decrease in both global and local efficiency, but an increase in clustering coefficient and the average shortest path length. We further found that the AD patients had significantly decreased nodal efficiency at the regional level, as well as weaker connections in multiple local cortical and subcortical regions, such as precuneus, temporal lobe, hippocampus, and thalamus. The HARDI model was found to be more advantageous than the DTI model, as it was more sensitive to the deficiencies in AD at all of the three levels.

  6. Numerical Analysis and Geometry Optimisation of Vertical Vane of Room Air-conditioner

    Directory of Open Access Journals (Sweden)

    Al-Obaidi Abdulkareem Sh. Mahdi

    2018-01-01

    Full Text Available Vertical vanes of room air-conditioners are used to control and direct cold air. This paper aims to study vertical vane as one of the parameters that affect the efficiency of dissipating cold air to a given space. The vertical vane geometry is analysed and optimised for lower production cost using CFD. The optimised geometry of the vertical vane should have the same or increased efficiency of dissipating cold air and have lesser mass compared to the existing original design. The existing original design of vertical vane is simplified and analysed by using ANSYS Fluent. Efficiency of wind direction is define as how accurate the direction of airflow coming out from vertical vane. In order to calculate the efficiency of wind direction, 15° and 30° rotation of vertical vane inside room air-conditioner are simulated. The efficiency of wind direction for 15° rotation of vertical vane is 57.81% while efficiency of wind direction for 30° rotation of vertical vane is 47.54%. The results of the efficiency of wind direction are used as base reference for parametric study. The parameters investigated for optimisation of vertical vane are focused at length of long span, tip chord and short span. The design of 15% decreased in vane surface area at tip chord is the best optimised design of vertical vane because the efficiency of wind direction is the highest as 60.32%.

  7. CFD optimisation of a stadium roof geometry: a qualitative study to improve the wind microenvironment

    Directory of Open Access Journals (Sweden)

    Sofotasiou Polytimi

    2017-01-01

    Full Text Available The complexity of the built environment requires the adoption of coupled techniques to predict the flow phenomena and provide optimum design solutions. In this study, coupled computational fluid dynamics (CFD and response surface methodology (RSM optimisation tools are employed to investigate the parameters that determine the wind comfort in a two-dimensional stadium model, by optimising the roof geometry. The roof height, width and length are evaluated against the flow homogeneity at the spectator terraces and the playing field area, the roof flow rate and the average interior pressure. Based on non-parametric regression analysis, both symmetric and asymmetric configurations are considered for optimisation. The optimum design solutions revealed that it is achievable to provide an improved wind environment in both playing field area and spectator terraces, giving a further insight on the interrelations of the parameters involved. Considering the limitations of conducting a two-dimensional study, the obtained results may beneficially be used as a basis for the optimisation of a complex three-dimensional stadium structure and thus become an important design guide for stadium structures.

  8. Thermodynamic optimisation and analysis of four Kalina cycle layouts for high temperature applications

    International Nuclear Information System (INIS)

    Modi, Anish; Haglind, Fredrik

    2015-01-01

    The Kalina cycle has seen increased interest in the last few years as an efficient alternative to the conventional steam Rankine cycle. However, the available literature gives little information on the algorithms to solve or optimise this inherently complex cycle. This paper presents a detailed approach to solve and optimise a Kalina cycle for high temperature (a turbine inlet temperature of 500 °C) and high pressure (over 100 bar) applications using a computationally efficient solution algorithm. A central receiver solar thermal power plant with direct steam generation was considered as a case study. Four different layouts for the Kalina cycle based on the number and/or placement of the recuperators in the cycle were optimised and compared based on performance parameters such as the cycle efficiency and the cooling water requirement. The cycles were modelled in steady state and optimised with the maximisation of the cycle efficiency as the objective function. It is observed that the different cycle layouts result in different regions for the optimal value of the turbine inlet ammonia mass fraction. Out of the four compared layouts, the most complex layout KC1234 gives the highest efficiency. The cooling water requirement is closely related to the cycle efficiency, i.e., the better the efficiency, the lower is the cooling water requirement. - Highlights: • Detailed methodology for solving and optimising Kalina cycle for high temperature applications. • A central receiver solar thermal power plant with direct steam generation considered as a case study. • Four Kalina cycle layouts based on the placement of recuperators optimised and compared

  9. Real-time optimisation of the Hoa Binh reservoir, Vietnam

    DEFF Research Database (Denmark)

    Richaud, Bertrand; Madsen, Henrik; Rosbjerg, Dan

    2011-01-01

    -time optimisation. First, the simulation-optimisation framework is applied for optimising reservoir operating rules. Secondly, real-time and forecast information is used for on-line optimisation that focuses on short-term goals, such as flood control or hydropower generation, without compromising the deviation...... in the downstream part of the Red River, and at the same time to increase hydropower generation and to save water for the dry season. The real-time optimisation procedure further improves the efficiency of the reservoir operation and enhances the flexibility for the decision-making. Finally, the quality......Multi-purpose reservoirs often have to be managed according to conflicting objectives, which requires efficient tools for trading-off the objectives. This paper proposes a multi-objective simulation-optimisation approach that couples off-line rule curve optimisation with on-line real...

  10. Acoustic Resonator Optimisation for Airborne Particle Manipulation

    Science.gov (United States)

    Devendran, Citsabehsan; Billson, Duncan R.; Hutchins, David A.; Alan, Tuncay; Neild, Adrian

    Advances in micro-electromechanical systems (MEMS) technology and biomedical research necessitate micro-machined manipulators to capture, handle and position delicate micron-sized particles. To this end, a parallel plate acoustic resonator system has been investigated for the purposes of manipulation and entrapment of micron sized particles in air. Numerical and finite element modelling was performed to optimise the design of the layered acoustic resonator. To obtain an optimised resonator design, careful considerations of the effect of thickness and material properties are required. Furthermore, the effect of acoustic attenuation which is dependent on frequency is also considered within this study, leading to an optimum operational frequency range. Finally, experimental results demonstrated good particle levitation and capture of various particle properties and sizes ranging to as small as 14.8 μm.

  11. Techno-economic optimisation of energy systems

    International Nuclear Information System (INIS)

    Mansilla Pellen, Ch.

    2006-07-01

    The traditional approach currently used to assess the economic interest of energy systems is based on a defined flow-sheet. Some studies have shown that the flow-sheets corresponding to the best thermodynamic efficiencies do not necessarily lead to the best production costs. A method called techno-economic optimisation was proposed. This method aims at minimising the production cost of a given energy system, including both investment and operating costs. It was implemented using genetic algorithms. This approach was compared to the heat integration method on two different examples, thus validating its interest. Techno-economic optimisation was then applied to different energy systems dealing with hydrogen as well as electricity production. (author)

  12. Pre-operative optimisation of lung function

    Directory of Open Access Journals (Sweden)

    Naheed Azhar

    2015-01-01

    Full Text Available The anaesthetic management of patients with pre-existing pulmonary disease is a challenging task. It is associated with increased morbidity in the form of post-operative pulmonary complications. Pre-operative optimisation of lung function helps in reducing these complications. Patients are advised to stop smoking for a period of 4–6 weeks. This reduces airway reactivity, improves mucociliary function and decreases carboxy-haemoglobin. The widely used incentive spirometry may be useful only when combined with other respiratory muscle exercises. Volume-based inspiratory devices have the best results. Pharmacotherapy of asthma and chronic obstructive pulmonary disease must be optimised before considering the patient for elective surgery. Beta 2 agonists, inhaled corticosteroids and systemic corticosteroids, are the main drugs used for this and several drugs play an adjunctive role in medical therapy. A graded approach has been suggested to manage these patients for elective surgery with an aim to achieve optimal pulmonary function.

  13. Use of universal functional optimisation for TL glow curve analysis

    International Nuclear Information System (INIS)

    Pernicka, F.; Linh, H.Q.

    1996-01-01

    The effective use of any TL instrument requires an efficient software package to be able to fulfil different tasks required by research and practical applications. One of the standard features of the package used at the NPI Prague is the application of the interactive modular system Universal Functional Optimisation (UFO) for glow curve deconvolution. The whole system has been tested on standard glow curves using different models of the TL process (a single peak described by the Podgorsak approximation, first order kinetics and/or general order kinetics). Calculated values of basic TL parameters (E and s) show a good agreement with the results obtained by other authors. The main advantage of the system is in its modularity that enables flexible changes in the TL model and mathematical procedures of the glow curve analysis. (author)

  14. Diffusion tensor imaging (DTI) findings in adult civilian, military, and sport-related mild traumatic brain injury (mTBI): a systematic critical review.

    Science.gov (United States)

    Asken, Breton Michael; DeKosky, Steven T; Clugston, James R; Jaffee, Michael S; Bauer, Russell M

    2018-04-01

    This review seeks to summarize diffusion tensor imaging (DTI) studies that have evaluated structural changes attributed to the mechanisms of mild traumatic brain injury (mTBI) in adult civilian, military, and athlete populations. Articles from 2002 to 2016 were retrieved from PubMed/MEDLINE, EBSCOhost, and Google Scholar, using a Boolean search string containing the following terms: "diffusion tensor imaging", "diffusion imaging", "DTI", "white matter", "concussion", "mild traumatic brain injury", "mTBI", "traumatic brain injury", and "TBI". We added studies not identified by this method that were found via manually-searched reference lists. We identified 86 eligible studies from English-language journals using, adult, human samples. Studies were evaluated based on duration between injury and DTI assessment, categorized as acute, subacute/chronic, remote mTBI, and repetitive brain trauma considerations. Since changes in brain structure after mTBI can also be affected by other co-occurring medical and demographic factors, we also briefly review DTI studies that have addressed socioeconomic status factors (SES), major depressive disorder (MDD), and attention-deficit hyperactivity disorder (ADHD). The review describes population-specific risks and the complications of clinical versus pathophysiological outcomes of mTBI. We had anticipated that the distinct population groups (civilian, military, and athlete) would require separate consideration, and various aspects of the study characteristics supported this. In general, study results suggested widespread but inconsistent differences in white matter diffusion metrics (primarily fractional anisotropy [FA], mean diffusivity [MD], radial diffusivity [RD], and axial diffusivity [AD]) following mTBI/concussion. Inspection of study designs and results revealed potential explanations for discrepant DTI findings, such as control group variability, analytic techniques, the manner in which regional differences were reported, and

  15. Optimised dipper fine tunes shovel performance

    Energy Technology Data Exchange (ETDEWEB)

    Fiscor, S.

    2005-06-01

    Joint efforts between mine operators, OEMs, and researchers yields unexpected benefits from dippers for shovels for coal, oil, or hardrock mining that can now be tailored to meet site-specific conditions. The article outlines a process being developed by CRCMining and P & H MIning Equipment to optimise the dipper that involves rapid prototyping and scale modelling of the dipper and the mine conditions. Scale models have been successfully field tested. 2 photos.

  16. Public transport optimisation emphasising passengers’ travel behaviour.

    OpenAIRE

    Jensen, Jens Parbo; Nielsen, Otto Anker; Prato, Carlo Giacomo

    2015-01-01

    Passengers in public transport complaining about their travel experiences are not uncommon. This might seem counterintuitive since several operators worldwide are presenting better key performance indicators year by year. The present PhD study focuses on developing optimisation algorithms to enhance the operations of public transport while explicitly emphasising passengers’ travel behaviour and preferences. Similar to economic theory, interactions between supply and demand are omnipresent in ...

  17. Natural Erosion of Sandstone as Shape Optimisation.

    Science.gov (United States)

    Ostanin, Igor; Safonov, Alexander; Oseledets, Ivan

    2017-12-11

    Natural arches, pillars and other exotic sandstone formations have always been attracting attention for their unusual shapes and amazing mechanical balance that leave a strong impression of intelligent design rather than the result of a stochastic process. It has been recently demonstrated that these shapes could have been the result of the negative feedback between stress and erosion that originates in fundamental laws of friction between the rock's constituent particles. Here we present a deeper analysis of this idea and bridge it with the approaches utilized in shape and topology optimisation. It appears that the processes of natural erosion, driven by stochastic surface forces and Mohr-Coulomb law of dry friction, can be viewed within the framework of local optimisation for minimum elastic strain energy. Our hypothesis is confirmed by numerical simulations of the erosion using the topological-shape optimisation model. Our work contributes to a better understanding of stochastic erosion and feasible landscape formations that could be found on Earth and beyond.

  18. Exploration of automatic optimisation for CUDA programming

    KAUST Repository

    Al-Mouhamed, Mayez

    2014-09-16

    © 2014 Taylor & Francis. Writing optimised compute unified device architecture (CUDA) program for graphic processing units (GPUs) is complex even for experts. We present a design methodology for a restructuring tool that converts C-loops into optimised CUDA kernels based on a three-step algorithm which are loop tiling, coalesced memory access and resource optimisation. A method for finding possible loop tiling solutions with coalesced memory access is developed and a simplified algorithm for restructuring C-loops into an efficient CUDA kernel is presented. In the evaluation, we implement matrix multiply (MM), matrix transpose (M-transpose), matrix scaling (M-scaling) and matrix vector multiply (MV) using the proposed algorithm. We present the analysis of the execution time and GPU throughput for the above applications, which favourably compare to other proposals. Evaluation is carried out while scaling the problem size and running under a variety of kernel configurations. The obtained speedup is about 28-35% for M-transpose compared to NVIDIA Software Development Kit, 33% speedup for MV compared to general purpose computation on graphics processing unit compiler, and more than 80% speedup for MM and M-scaling compared to CUDA-lite.

  19. Exploration of automatic optimisation for CUDA programming

    KAUST Repository

    Al-Mouhamed, Mayez; Khan, Ayaz ul Hassan

    2014-01-01

    © 2014 Taylor & Francis. Writing optimised compute unified device architecture (CUDA) program for graphic processing units (GPUs) is complex even for experts. We present a design methodology for a restructuring tool that converts C-loops into optimised CUDA kernels based on a three-step algorithm which are loop tiling, coalesced memory access and resource optimisation. A method for finding possible loop tiling solutions with coalesced memory access is developed and a simplified algorithm for restructuring C-loops into an efficient CUDA kernel is presented. In the evaluation, we implement matrix multiply (MM), matrix transpose (M-transpose), matrix scaling (M-scaling) and matrix vector multiply (MV) using the proposed algorithm. We present the analysis of the execution time and GPU throughput for the above applications, which favourably compare to other proposals. Evaluation is carried out while scaling the problem size and running under a variety of kernel configurations. The obtained speedup is about 28-35% for M-transpose compared to NVIDIA Software Development Kit, 33% speedup for MV compared to general purpose computation on graphics processing unit compiler, and more than 80% speedup for MM and M-scaling compared to CUDA-lite.

  20. Optimisation and symmetry in experimental radiation physics

    International Nuclear Information System (INIS)

    Ghose, A.

    1988-01-01

    The present monograph is concerned with the optimisation of geometric factors in radiation physics experiments. The discussions are essentially confined to those systems in which optimisation is equivalent to symmetrical configurations of the measurement systems. They include, measurements of interaction cross section of diverse types, determination of polarisations, development of detectors with almost ideal characteristics, production of radiations with continuously variable energies and development of high efficiency spectrometers etc. The monograph is intended for use by experimental physicists investigating primary interactions of radiations with matter and associated technologies. We have illustrated the various optimisation procedures by considering the cases of the so-called ''14 MeV'' on d-t neutrons and gamma rays with energies less than 3 MeV. Developments in fusion technology are critically dependent on the availability accurate cross sections of nuclei for fast neutrons of energies at least as high as d-t neutrons. In this monograph we have discussed various techniques which can be used to improve the accuracy of such measurements and have also presented a method for generating almost monoenergetic neutrons in the 8 MeV to 13 MeV energy range which can be used to measure cross sections in this sparingly investigated region

  1. Optimisation of Protection as applicable to geological disposal: the ICRP view

    International Nuclear Information System (INIS)

    Weiss, W.

    2010-01-01

    Wolfgang Weiss (BfS), vice-chair of ICRP Committee 4, recalled that the role of optimisation is to select the best protection options under the prevailing circumstances based on scientific considerations, societal concerns and ethical aspects as well as considerations of transparency. An important role of the concept of optimisation of protection is to foster a 'safety culture' and thereby to engender a state of thinking in everyone responsible for control of radiation exposures, such that they are continuously asking themselves the question, 'Have I done all that I reasonably can to avoid or reduce these doses?' Clearly, the answer to this question is a matter of judgement and necessitates co-operation between all parties involved and, as a minimum, the operating management and the regulatory agencies, but the dialogue would be more complete if other stakeholders were also involved. What kinds of checks and balances or factors would be needed to be considered for an 'optimal' system? Can indicators be identified? Quantitative methods may provide input to this dialogue but they should never be the sole input. The ICRP considers that the parameters to take into account include also social considerations and values, environmental considerations, as well as technical and economic considerations. Wolfgang Weiss approached the question of the distinction to be made between system optimisation (in the sense of taking account of social and economic as well as of all types of hazards) and optimisation of radiological protection. The position of the ICRP is that the system of protection that it proposes is based on both science (quantification of the health risk) and value judgement (what is an acceptable risk?) and optimisation is the recommended process to integrate both aspects. Indeed, there has been evolution since the old system of intervention levels to the new system, whereby, even if the level of the dose or risk (which is called constraint in ICRP-81 ) is met

  2. Artificial Intelligence Mechanisms on Interactive Modified Simplex Method with Desirability Function for Optimising Surface Lapping Process

    Directory of Open Access Journals (Sweden)

    Pongchanun Luangpaiboon

    2014-01-01

    Full Text Available A study has been made to optimise the influential parameters of surface lapping process. Lapping time, lapping speed, downward pressure, and charging pressure were chosen from the preliminary studies as parameters to determine process performances in terms of material removal, lap width, and clamp force. The desirability functions of the-nominal-the-best were used to compromise multiple responses into the overall desirability function level or D response. The conventional modified simplex or Nelder-Mead simplex method and the interactive desirability function are performed to optimise online the parameter levels in order to maximise the D response. In order to determine the lapping process parameters effectively, this research then applies two powerful artificial intelligence optimisation mechanisms from harmony search and firefly algorithms. The recommended condition of (lapping time, lapping speed, downward pressure, and charging pressure at (33, 35, 6.0, and 5.0 has been verified by performing confirmation experiments. It showed that the D response level increased to 0.96. When compared with the current operating condition, there is a decrease of the material removal and lap width with the improved process performance indices of 2.01 and 1.14, respectively. Similarly, there is an increase of the clamp force with the improved process performance index of 1.58.

  3. Experimental Investigation and Taguchi Optimisation of Drilling Properties on Teak Wood Reinforced Epoxy Resin

    Science.gov (United States)

    Lilly Mercy, J.; Shaqir Tanvir, Mohamed; Swaroopkanth, K.

    2017-05-01

    The drilling properties of teak reinforced epoxy resin composite are explored in this work. The thrust force and temperature during the drilling process was found and optimised. Nine holes were drilled in accordance with L9 orthogonal array on Medium Density Fibre board and Teak wood reinforced epoxy composite board and the thrust force and temperature induced during drilling is measured. Drilling experiments were conducted using CNC Vertical drilling machine and the thrust force was measured using dynamometer and temperature using infra-red thermometer. The experiments were conducted with varying levels of spindle speed and feed rate and optimised using Taguchi optimisation. It was observed that higher thrust and temperature were observed while drilling teak wood composite due to the high mechanical strength of teak wood. The hard and brittle properties of the resin seemed to be more pronounced in the composite. The experimental results were optimised to find the best combination of input parameters for reduced thrust and temperature. When speed increases, thrust force decreases and temperature increases. When feed increases, thrust force increases and temperature decreases. Experimental findings encouragesto use teak wood reinforced epoxy resin as a substitute for the traditionally used Medium Density Fibre Board. The percentage of mixing of teak dust can be increased with various resin combinations to arrive at the best suitable combination for obtaining optimal mechanical properties.

  4. Optimised sensitivity to leptonic CP violation from spectral information: the LBNO case at 2300 km baseline

    CERN Document Server

    Agarwalla, S K; Aittola, M; Alekou, A; Andrieu, B; Antoniou, F; Asfandiyarov, R; Autiero, D; Bésida, O; Balik, A; Ballett, P; Bandac, I; Banerjee, D; Bartmann, W; Bay, F; Biskup, B; Blebea-Apostu, A M; Blondel, A; Bogomilov, M; Bolognesi, S; Borriello, E; Brancus, I; Bravar, A; Buizza-Avanzini, M; Caiulo, D; Calin, M; Calviani, M; Campanelli, M; Cantini, C; Cata-Danil, G; Chakraborty, S; Charitonidis, N; Chaussard, L; Chesneanu, D; Chipesiu, F; Crivelli, P; Dawson, J; De Bonis, I; Declais, Y; Sanchez, P Del Amo; Delbart, A; Di Luise, S; Duchesneau, D; Dumarchez, J; Efthymiopoulos, I; Eliseev, A; Emery, S; Enqvist, T; Enqvist, K; Epprecht, L; Erykalov, A N; Esanu, T; Franco, D; Friend, M; Galymov, V; Gavrilov, G; Gendotti, A; Giganti, C; Gilardoni, S; Goddard, B; Gomoiu, C M; Gornushkin, Y A; Gorodetzky, P; Haesler, A; Hasegawa, T; Horikawa, S; Huitu, K; Izmaylov, A; Jipa, A; Kainulainen, K; Karadzhov, Y; Khabibullin, M; Khotjantsev, A; Kopylov, A N; Korzenev, A; Kosyanenko, S; Kryn, D; Kudenko, Y; Kuusiniemi, P; Lazanu, I; Lazaridis, C; Levy, J -M; Loo, K; Maalampi, J; Margineanu, R M; Marteau, J; Martin-Mari, C; Matveev, V; Mazzucato, E; Mefodiev, A; Mineev, O; Mirizzi, A; Mitrica, B; Murphy, S; Nakadaira, T; Narita, S; Nesterenko, D A; Nguyen, K; Nikolics, K; Noah, E; Novikov, Yu; Oprima, A; Osborne, J; Ovsyannikova, T; Papaphilippou, Y; Pascoli, S; Patzak, T; Pectu, M; Pennacchio, E; Periale, L; Pessard, H; Popov, B; Ravonel, M; Rayner, M; Resnati, F; Ristea, O; Robert, A; Rubbia, A; Rummukainen, K; Saftoiu, A; Sakashita, K; Sanchez-Galan, F; Sarkamo, J; Saviano, N; Scantamburlo, E; Sergiampietri, F; Sgalaberna, D; Shaposhnikova, E; Slupecki, M; Smargianaki, D; Stanca, D; Steerenberg, R; Sterian, A R; Sterian, P; Stoica, S; Strabel, C; Suhonen, J; Suvorov, V; Toma, G; Tonazzo, A; Trzaska, W H; Tsenov, R; Tuominen, K; Valram, M; Vankova-Kirilova, G; Vannucci, F; Vasseur, G; Velotti, F; Velten, P; Venturi, V; Viant, T; Vihonen, S; Vincke, H; Vorobyev, A; Weber, A; Wu, S; Yershov, N; Zambelli, L; Zito, M

    2014-01-01

    One of the main goals of the Long Baseline Neutrino Observatory (LBNO) is to study the $L/E$ behaviour (spectral information) of the electron neutrino and antineutrino appearance probabilities, in order to determine the unknown CP-violation phase $\\delta_{CP}$ and discover CP-violation in the leptonic sector. The result is based on the measurement of the appearance probabilities in a broad range of energies, covering t he 1st and 2nd oscillation maxima, at a very long baseline of 2300 km. The sensitivity of the experiment can be maximised by optimising the energy spectra of the neutrino and anti-neutrino fluxes. Such an optimisation requires exploring an extended range of parameters describing in details the geometries and properties of the primary protons, hadron target and focusing elements in the neutrino beam line. In this paper we present a numerical solution that leads to an optimised energy spectra and study its impact on the sensitivity of LBNO to discover leptonic CP violation. In the optimised flux ...

  5. Identification of the mechanical behaviour of biopolymer composites using multistart optimisation technique

    KAUST Repository

    Brahim, Elhacen

    2013-10-01

    This paper aims at identifying the mechanical behaviour of starch-zein composites as a function of zein content using a novel optimisation technique. Starting from bending experiments, force-deflection response is used to derive adequate mechanical parameters representing the elastic-plastic behaviour of the studied material. For such a purpose, a finite element model is developed accounting for a simple hardening rule, namely isotropic hardening model. A deterministic optimisation strategy is implemented to provide rapid matching between parameters of the constitutive law and the observed behaviour. Results are discussed based on the robustness of the numerical approach and predicted tendencies with regards to the role of zein content. © 2013 Elsevier Ltd.

  6. Medio-dorsal thalamus and confabulations: Evidence from a clinical case and combined MRI/DTI study

    Directory of Open Access Journals (Sweden)

    Valeria Onofrj

    2016-01-01

    Full Text Available The Medio-Dorsal Nuclei (MDN including the thalamic magnocellular and parvocellular thalamic regions has been implicated in verbal memory function. In a 77 year old lady, with a prior history of a clinically silent infarct of the left MDN, we observed the acute onset of spontaneous confabulations when an isolated new infarct occurred in the right MDN. The patient and five age-matched healthy subjects underwent Magnetic Resonance Imaging (MRI and Diffusion Tensor Imaging (DTI. The thalamic lesions were localized by overlapping Morel Thalamic Atlas with structural MRI data. DTI was used to assess: i white matter alterations (Fractional Anisotropy, FA within fibers connecting the ischemic areas to cortex; ii the micro-structural damage (Mean Diffusivity within the thalamic sub-regions defined by their structural connectivity to the Anterior Cingulate Cortex (ACC and to the temporal lobes. These target regions were chosen because their damage is considered associated with the appearance of confabulations. Thalamic lesions were localized within the parvocellular regions of the right and left MDNs. The structural connectivity study showed that the fiber tracts, connecting the bilaterally damaged thalamic regions with the frontal cortex, corresponded to the anterior thalamic radiations (ATR. FA within these tracts was significantly lower in the patient as compared to controls. Mean diffusivity within the MDNs projecting to Broadman area (BA 24, BA25 and BA32 of ACC was significantly higher in the patient than in control group. Mean diffusivity values within the MDN projecting to temporal lobes in contrast were not different between patient and controls. Our findings suggest the involvement of bilateral MDNs projections to ACC in the genesis of confabulations and help provide clarity to the longstanding debate on the origin of confabulations.

  7. Structural and functional abnormalities of default mode network in minimal hepatic encephalopathy: a study combining DTI and fMRI.

    Directory of Open Access Journals (Sweden)

    Rongfeng Qi

    Full Text Available BACKGROUND AND PURPOSE: Live failure can cause brain edema and aberrant brain function in cirrhotic patients. In particular, decreased functional connectivity within the brain default-mode network (DMN has been recently reported in overt hepatic encephalopathy (HE patients. However, so far, little is known about the connectivity among the DMN in the minimal HE (MHE, the mildest form of HE. Here, we combined diffusion tensor imaging (DTI and resting-state functional MRI (rs-fMRI to test our hypothesis that both structural and functional connectivity within the DMN were disturbed in MHE. MATERIALS AND METHODS: Twenty MHE patients and 20 healthy controls participated in the study. We explored the changes of structural (path length, tracts count, fractional anisotropy [FA] and mean diffusivity [MD] derived from DTI tractography and functional (temporal correlation coefficient derived from rs-fMRI connectivity of the DMN in MHE patients. Pearson correlation analysis was performed between the structural/functional indices and venous blood ammonia levels/neuropsychological tests scores of patients. All thresholds were set at P<0.05, Bonferroni corrected. RESULTS: Compared to the healthy controls, MHE patients showed both decreased FA and increased MD in the tract connecting the posterior cingulate cortex/precuneus (PCC/PCUN to left parahippocampal gyrus (PHG, and decreased functional connectivity between the PCC/PCUN and left PHG, and medial prefrontal cortex (MPFC. MD values of the tract connecting PCC/PCUN to the left PHG positively correlated to the ammonia levels, the temporal correlation coefficients between the PCC/PCUN and the MPFC showed positive correlation to the digital symbol tests scores of patients. CONCLUSION: MHE patients have both disturbed structural and functional connectivity within the DMN. The decreased functional connectivity was also detected between some regions without abnormal structural connectivity, suggesting that the

  8. Alterations of brain network hubs in reflex syncope: Evidence from a graph theoretical analysis based on DTI.

    Science.gov (United States)

    Park, Bong Soo; Lee, Yoo Jin; Park, Jin-Han; Kim, Il Hwan; Park, Si Hyung; Lee, Ho-Joon; Park, Kang Min

    2018-06-01

    We evaluated global topology and organization of regional hubs in the brain networks and microstructural abnormalities in the white matter of patients with reflex syncope. Twenty patients with reflex syncope and thirty healthy subjects were recruited, and they underwent diffusion tensor imaging (DTI) scans. Graph theory was applied to obtain network measures based on extracted DTI data, using DSI Studio. We then investigated differences in the network measures between the patients with reflex syncope and the healthy subjects. We also analyzed microstructural abnormalities of white matter using tract-based spatial statistics analysis (TBSS). Measures of global topology were not different between patients with reflex syncope and healthy subjects. However, in reflex syncope patients, the strength measures of the right angular, left inferior frontal, left middle orbitofrontal, left superior medial frontal, and left middle temporal gyrus were lower than in healthy subjects. The betweenness centrality measures of the left middle orbitofrontal, left fusiform, and left lingual gyrus in patients were lower than those in healthy subjects. The PageRank centrality measures of the right angular, left middle orbitofrontal, and left superior medial frontal gyrus in patients were lower than those in healthy subjects. Regarding the analysis of the white matter microstructure, there were no differences in the fractional anisotropy and mean diffusivity values between the two groups. We have identified a reorganization of network hubs in the brain network of patients with reflex syncope. These alterations in brain network may play a role in the pathophysiologic mechanism underlying reflex syncope. © 2018 The Authors. Brain and Behavior published by Wiley Periodicals, Inc.

  9. Optimisation of resolution in micellar electrokinetic chromatography by multivariate evaluation of electrolytes.

    Science.gov (United States)

    Mikaeli, S; Thorsén, G; Karlberg, B

    2001-01-12

    A novel approach to multivariate evaluation of separation electrolytes for micellar electrokinetic chromatography is presented. An initial screening of the experimental parameters is performed using a Plackett-Burman design. Significant parameters are further evaluated using full factorial designs. The total resolution of the separation is calculated and used as response. The proposed scheme has been applied to the optimisation of the separation of phenols and the chiral separation of (+)-1-(9-anthryl)-2-propyl chloroformate-derivatized amino acids. A total of eight experimental parameters were evaluated and optimal conditions found in less than 48 experiments.

  10. Estimation of the Influence of Power System Mathematical Model Parameter Uncertainty on PSS2A System Stabilizers

    Directory of Open Access Journals (Sweden)

    Adrian Nocoń

    2015-09-01

    Full Text Available This paper presents an analysis of the influence of uncertainty of power system mathematical model parameters on optimised parameters of PSS2A system stabilizers. Optimisation of power system stabilizer parameters was based on polyoptimisation (multi-criteria optimisation. Optimisation criteria were determined for disturbances occurring in a multi-machine power system, when taking into account transient waveforms associated with electromechanical swings (instantaneous power, angular speed and terminal voltage waveforms of generators. A genetic algorithm with floating-point encoding, tournament selection, mean crossover and perturbative mutations, modified for the needs of investigations, was used for optimisation. The impact of uncertainties on the quality of operation of power system stabilizers with optimised parameters has been evaluated using various deformation factors.

  11. Mechatronic System Design Based On An Optimisation Approach

    DEFF Research Database (Denmark)

    Andersen, Torben Ole; Pedersen, Henrik Clemmensen; Hansen, Michael Rygaard

    The envisaged objective of this paper project is to extend the current state of the art regarding the design of complex mechatronic systems utilizing an optimisation approach. We propose to investigate a novel framework for mechatronic system design. The novelty and originality being the use...... of optimisation techniques. The methods used to optimise/design within the classical disciplines will be identified and extended to mechatronic system design....

  12. Analysis and optimisation of heterogeneous real-time embedded systems

    DEFF Research Database (Denmark)

    Pop, Paul; Eles, Petru; Peng, Zebo

    2005-01-01

    . The success of such new design methods depends on the availability of analysis and optimisation techniques. Analysis and optimisation techniques for heterogeneous real-time embedded systems are presented in the paper. The authors address in more detail a particular class of such systems called multi...... of application messages to frames. Optimisation heuristics for frame packing aimed at producing a schedulable system are presented. Extensive experiments and a real-life example show the efficiency of the frame-packing approach....

  13. Analysis and optimisation of heterogeneous real-time embedded systems

    DEFF Research Database (Denmark)

    Pop, Paul; Eles, Petru; Peng, Zebo

    2006-01-01

    . The success of such new design methods depends on the availability of analysis and optimisation techniques. Analysis and optimisation techniques for heterogeneous real-time embedded systems are presented in the paper. The authors address in more detail a particular class of such systems called multi...... of application messages to frames. Optimisation heuristics for frame packing aimed at producing a schedulable system are presented. Extensive experiments and a real-life example show the efficiency of the frame-packing approach....

  14. Flotation process control optimisation at Prominent Hill

    International Nuclear Information System (INIS)

    Lombardi, Josephine; Muhamad, Nur; Weidenbach, M.

    2012-01-01

    OZ Minerals' Prominent Hill copper- gold concentrator is located 130 km south east of the town of Coober Pedy in the Gawler Craton of South Australia. The concentrator was built in 2008 and commenced commercial production in early 2009. The Prominent Hill concentrator is comprised of a conventional grinding and flotation processing plant with a 9.6 Mtpa ore throughput capacity. The flotation circuit includes six rougher cells, an IseMill for regrinding the rougher concentrate and a Jameson cell heading up the three stage conventional cell cleaner circuit. In total there are four level controllers in the rougher train and ten level controllers in the cleaning circuit for 18 cells. Generic proportional — integral and derivative (PID) control used on the level controllers alone propagated any disturbances downstream in the circuit that were generated from the grinding circuit, hoppers, between cells and interconnected banks of cells, having a negative impact on plant performance. To better control such disturbances, FloatStar level stabiliser was selected for installation on the flotation circuit to account for the interaction between the cells. Multivariable control was also installed on the five concentrate hoppers to maintain consistent feed to the cells and to the IsaMill. An additional area identified for optimisation in the flotation circuit was the mass pull rate from the rougher cells. FloatStar flow optimiser was selected to be installed subsequent to the FloatStar level stabiliser. This allowed for a unified, consistent and optimal approach to running the rougher circuit. This paper describes the improvement in the stabilisation of the circuit achieved by the FloatStar level stabiliser by using the interaction matrix between cell level controllers and the results and benefits of implementing the FloatStar flow optimiser on the rougher train.

  15. Risk based test interval and maintenance optimisation - Application and uses

    International Nuclear Information System (INIS)

    Sparre, E.

    1999-10-01

    The project is part of an IAEA co-ordinated Research Project (CRP) on 'Development of Methodologies for Optimisation of Surveillance Testing and Maintenance of Safety Related Equipment at NPPs'. The purpose of the project is to investigate the sensitivity of the results obtained when performing risk based optimisation of the technical specifications. Previous projects have shown that complete LPSA models can be created and that these models allow optimisation of technical specifications. However, these optimisations did not include any in depth check of the result sensitivity with regards to methods, model completeness etc. Four different test intervals have been investigated in this study. Aside from an original, nominal, optimisation a set of sensitivity analyses has been performed and the results from these analyses have been compared to the original optimisation. The analyses indicate that the result of an optimisation is rather stable. However, it is not possible to draw any certain conclusions without performing a number of sensitivity analyses. Significant differences in the optimisation result were discovered when analysing an alternative configuration. Also deterministic uncertainties seem to affect the result of an optimisation largely. The sensitivity of failure data uncertainties is important to investigate in detail since the methodology is based on the assumption that the unavailability of a component is dependent on the length of the test interval

  16. Improving Vector Evaluated Particle Swarm Optimisation by incorporating nondominated solutions.

    Science.gov (United States)

    Lim, Kian Sheng; Ibrahim, Zuwairie; Buyamin, Salinda; Ahmad, Anita; Naim, Faradila; Ghazali, Kamarul Hawari; Mokhtar, Norrima

    2013-01-01

    The Vector Evaluated Particle Swarm Optimisation algorithm is widely used to solve multiobjective optimisation problems. This algorithm optimises one objective using a swarm of particles where their movements are guided by the best solution found by another swarm. However, the best solution of a swarm is only updated when a newly generated solution has better fitness than the best solution at the objective function optimised by that swarm, yielding poor solutions for the multiobjective optimisation problems. Thus, an improved Vector Evaluated Particle Swarm Optimisation algorithm is introduced by incorporating the nondominated solutions as the guidance for a swarm rather than using the best solution from another swarm. In this paper, the performance of improved Vector Evaluated Particle Swarm Optimisation algorithm is investigated using performance measures such as the number of nondominated solutions found, the generational distance, the spread, and the hypervolume. The results suggest that the improved Vector Evaluated Particle Swarm Optimisation algorithm has impressive performance compared with the conventional Vector Evaluated Particle Swarm Optimisation algorithm.

  17. Improving Vector Evaluated Particle Swarm Optimisation by Incorporating Nondominated Solutions

    Directory of Open Access Journals (Sweden)

    Kian Sheng Lim

    2013-01-01

    Full Text Available The Vector Evaluated Particle Swarm Optimisation algorithm is widely used to solve multiobjective optimisation problems. This algorithm optimises one objective using a swarm of particles where their movements are guided by the best solution found by another swarm. However, the best solution of a swarm is only updated when a newly generated solution has better fitness than the best solution at the objective function optimised by that swarm, yielding poor solutions for the multiobjective optimisation problems. Thus, an improved Vector Evaluated Particle Swarm Optimisation algorithm is introduced by incorporating the nondominated solutions as the guidance for a swarm rather than using the best solution from another swarm. In this paper, the performance of improved Vector Evaluated Particle Swarm Optimisation algorithm is investigated using performance measures such as the number of nondominated solutions found, the generational distance, the spread, and the hypervolume. The results suggest that the improved Vector Evaluated Particle Swarm Optimisation algorithm has impressive performance compared with the conventional Vector Evaluated Particle Swarm Optimisation algorithm.

  18. Optimising end of generation of Magnox reactors

    International Nuclear Information System (INIS)

    Hall, D.; Hopper, E.D.A.

    2014-01-01

    Designing, justifying and gaining regulatory approval for optimised, terminal fuel cycles for the last 4 of the 13 strong Magnox Fleet is described, covering: - constraints set by the plant owner's integrated closure plan, opportunities for innovative fuel cycles while preserving flexibility to respond to business changes; - methods of collectively determining best options for each site; - selected strategies including lower fuel element retention and inter-reactor transfer of fuel; - the required work scope, its technical, safety case and resource challenges and how they were met; - achieving additional electricity generation worth in excess of Pound 1 b from 4 sites (a total of 8 reactors); - the keys to success. (authors)

  19. Advanced manufacturing: optimising the factories of tomorrow

    International Nuclear Information System (INIS)

    Philippon, Patrick

    2013-01-01

    Faced with competition Patrick Philippon - Les Defis du CEA no.179 - April 2013 from the emerging countries, the competitiveness of the industrialised nations depends on the ability of their industries to innovate. This strategy necessarily entails the reorganisation and optimisation of the production systems. This is the whole challenge for 'advanced manufacturing', which relies on the new information and communication technologies. Interactive robotics, virtual reality and non-destructive testing are all technological building blocks developed by CEA, now approved within a cross-cutting programme, to meet the needs of industry and together build the factories of tomorrow. (author)

  20. Biorefinery plant design, engineering and process optimisation

    DEFF Research Database (Denmark)

    Holm-Nielsen, Jens Bo; Ehimen, Ehiazesebhor Augustine

    2014-01-01

    Before new biorefinery systems can be implemented, or the modification of existing single product biomass processing units into biorefineries can be carried out, proper planning of the intended biorefinery scheme must be performed initially. This chapter outlines design and synthesis approaches...... applicable for the planning and upgrading of intended biorefinery systems, and includes discussions on the operation of an existing lignocellulosic-based biorefinery platform. Furthermore, technical considerations and tools (i.e., process analytical tools) which could be applied to optimise the operations...... of existing and potential biorefinery plants are elucidated....

  1. Specification, Verification and Optimisation of Business Processes

    DEFF Research Database (Denmark)

    Herbert, Luke Thomas

    is extended with stochastic branching, message passing and reward annotations which allow for the modelling of resources consumed during the execution of a business process. Further, it is shown how this structure can be used to formalise the established business process modelling language Business Process...... fault tree analysis and the automated optimisation of business processes by means of an evolutionary algorithm. This work is motivated by problems that stem from the healthcare sector, and examples encountered in this field are used to illustrate these developments....

  2. Topology Optimisation for Coupled Convection Problems

    DEFF Research Database (Denmark)

    Alexandersen, Joe; Andreasen, Casper Schousboe; Aage, Niels

    stabilised finite elements implemented in a parallel multiphysics analysis and optimisation framework DFEM [1], developed and maintained in house. Focus is put on control of the temperature field within the solid structure and the problems can therefore be seen as conjugate heat transfer problems, where heat...... conduction governs in the solid parts of the design domain and couples to convection-dominated heat transfer to a surrounding fluid. Both loosely coupled and tightly coupled problems are considered. The loosely coupled problems are convection-diffusion problems, based on an advective velocity field from...

  3. Cost optimisation studies of high power accelerators

    Energy Technology Data Exchange (ETDEWEB)

    McAdams, R.; Nightingale, M.P.S.; Godden, D. [AEA Technology, Oxon (United Kingdom)] [and others

    1995-10-01

    Cost optimisation studies are carried out for an accelerator based neutron source consisting of a series of linear accelerators. The characteristics of the lowest cost design for a given beam current and energy machine such as power and length are found to depend on the lifetime envisaged for it. For a fixed neutron yield it is preferable to have a low current, high energy machine. The benefits of superconducting technology are also investigated. A Separated Orbit Cyclotron (SOC) has the potential to reduce capital and operating costs and intial estimates for the transverse and longitudinal current limits of such machines are made.

  4. Research article – Optimisation of paediatrics computed radiographyfor full spine curvature measurements using a phantom: a pilot study

    NARCIS (Netherlands)

    de Haan, Seraphine; Reis, Cláudia; Ndlovu, Junior; Serrenho, Catarina; Akhtar, Ifrah; Garcia, José Antonio; Linde, Daniël; Thorskog, Martine; Franco, Loris; Hogg, Peter

    2015-01-01

    Aim: Optimise a set of exposure factors, with the lowest effective dose, to delineate spinal curvature with the modified Cobb method in a full spine using computed radiography (CR) for a 5-year-old paediatric anthropomorphic phantom. Methods: Images were acquired by varying a set of parameters:

  5. Optimisation-based worst-case analysis and anti-windup synthesis for uncertain nonlinear systems

    Science.gov (United States)

    Menon, Prathyush Purushothama

    This thesis describes the development and application of optimisation-based methods for worst-case analysis and anti-windup synthesis for uncertain nonlinear systems. The worst-case analysis methods developed in the thesis are applied to the problem of nonlinear flight control law clearance for highly augmented aircraft. Local, global and hybrid optimisation algorithms are employed to evaluate worst-case violations of a nonlinear response clearance criterion, for a highly realistic aircraft simulation model and flight control law. The reliability and computational overheads associated with different opti misation algorithms are compared, and the capability of optimisation-based approaches to clear flight control laws over continuous regions of the flight envelope is demonstrated. An optimisation-based method for computing worst-case pilot inputs is also developed, and compared with current industrial approaches for this problem. The importance of explicitly considering uncertainty in aircraft parameters when computing worst-case pilot demands is clearly demonstrated. Preliminary results on extending the proposed framework to the problems of limit-cycle analysis and robustness analysis in the pres ence of time-varying uncertainties are also included. A new method for the design of anti-windup compensators for nonlinear constrained systems controlled using nonlinear dynamics inversion control schemes is presented and successfully applied to some simple examples. An algorithm based on the use of global optimisation is proposed to design the anti-windup compensator. Some conclusions are drawn from the results of the research presented in the thesis, and directions for future work are identified.

  6. HVAC system optimisation-in-building section

    Energy Technology Data Exchange (ETDEWEB)

    Lu, L.; Cai, W.; Xie, L.; Li, S.; Soh, Y.C. [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore (Singapore)

    2004-07-01

    This paper presents a practical method to optimise in-building section of centralised Heating, Ventilation and Air-Conditioning (HVAC) systems which consist of indoor air loops and chilled water loops. First, through component characteristic analysis, mathematical models associated with cooling loads and energy consumption for heat exchangers and energy consuming devices are established. By considering variation of cooling load of each end user, adaptive neuro-fuzzy inference system (ANFIS) is employed to model duct and pipe networks and obtain optimal differential pressure (DP) set points based on limited sensor information. A mix-integer nonlinear constraint optimization of system energy is formulated and solved by a modified genetic algorithm. The main feature of our paper is a systematic approach in optimizing the overall system energy consumption rather than that of individual component. A simulation study for a typical centralized HVAC system is provided to compare the proposed optimisation method with traditional ones. The results show that the proposed method indeed improves the system performance significantly. (author)

  7. Noise aspects at aerodynamic blade optimisation projects

    Energy Technology Data Exchange (ETDEWEB)

    Schepers, J.G. [Netherlands Energy Research Foundation, Petten (Netherlands)

    1997-12-31

    This paper shows an example of an aerodynamic blade optimisation, using the program PVOPT. PVOPT calculates the optimal wind turbine blade geometry such that the maximum energy yield is obtained. Using the aerodynamic optimal blade design as a basis, the possibilities of noise reduction are investigated. The aerodynamic optimised geometry from PVOPT is the `real` optimum (up to the latest decimal). The most important conclusion from this study is, that it is worthwhile to investigate the behaviour of the objective function (in the present case the energy yield) around the optimum: If the optimum is flat, there is a possibility to apply modifications to the optimum configuration with only a limited loss in energy yield. It is obvious that the modified configurations emits a different (and possibly lower) noise level. In the BLADOPT program (the successor of PVOPT) it will be possible to quantify the noise level and hence to assess the reduced noise emission more thoroughly. At present the most promising approaches for noise reduction are believed to be a reduction of the rotor speed (if at all possible), and a reduction of the tip angle by means of low lift profiles, or decreased twist at the outboard stations. These modifications were possible without a significant loss in energy yield. (LN)

  8. Diffusion tensor imaging parameters' changes of cerebellar hemispheres in Parkinson's disease

    Energy Technology Data Exchange (ETDEWEB)

    Mormina, Enricomaria; Arrigo, Alessandro; Granata, Francesca; Anastasi, Giuseppe P.; Gaeta, Michele [University of Messina, Department of Biomedical Science and Morphological and Functional Images, Messina (Italy); Calamuneri, Alessandro; Quartarone, Angelo [University of Messina, Department of Neurosciences, Messina (Italy); Ghilardi, Maria F.; Inglese, Matilde; Di Rocco, Alessandro [Mount Sinai Hospital, New York, NY (United States); Milardi, Demetrio [University of Messina, Department of Biomedical Science and Morphological and Functional Images, Messina (Italy); IRCCS Centro Neurolesi Bonino Pulejo, Messina (Italy)

    2015-03-01

    Studies with diffusion tensor imaging (DTI) analysis have produced conflicting information about the involvement of the cerebellar hemispheres in Parkinson's disease (PD). We, thus, used a new approach for the analysis of DTI parameters in order to ascertain the involvement of the cerebellum in PD. We performed a fiber tract-based analysis of cerebellar peduncles and cerebellar hemispheres in 16 healthy subjects and in 16 PD patients with more than 5 years duration of disease, using a 3T MRI scanner and a constrained spherical deconvolution (CSD) approach for tractographic reconstructions. In addition, we performed statistical analysis of DTI parameters and fractional anisotropy (FA) XYZ direction samplings. We found a statistically significant decrement of FA values in PD patients compared to controls (p < 0.05). In addition, extrapolating and analyzing FA XYZ direction samplings for each patient and each control, we found that this result was due to a stronger decrement of FA values along the Y axis (antero-posterior direction) (p < 0.01); FA changes along X and Z axes were not statistically significant (p > 0.05). We confirmed also no statistically significant differences of FA and apparent diffusion coefficient (ADC) for cerebellar peduncles in PD patients compared to healthy controls. The DTI-based cerebellar abnormalities in PD could constitute an advance in the knowledge of this disease. We demonstrated a statistically significant reduction of FA in cerebellar hemispheres of PD patients compared to healthy controls. Our work also demonstrated that the use of more sophisticated approaches in the DTI parameter analysis could potentially have a clinical relevance. (orig.)

  9. Diffusion tensor imaging parameters' changes of cerebellar hemispheres in Parkinson's disease

    International Nuclear Information System (INIS)

    Mormina, Enricomaria; Arrigo, Alessandro; Granata, Francesca; Anastasi, Giuseppe P.; Gaeta, Michele; Calamuneri, Alessandro; Quartarone, Angelo; Ghilardi, Maria F.; Inglese, Matilde; Di Rocco, Alessandro; Milardi, Demetrio

    2015-01-01

    Studies with diffusion tensor imaging (DTI) analysis have produced conflicting information about the involvement of the cerebellar hemispheres in Parkinson's disease (PD). We, thus, used a new approach for the analysis of DTI parameters in order to ascertain the involvement of the cerebellum in PD. We performed a fiber tract-based analysis of cerebellar peduncles and cerebellar hemispheres in 16 healthy subjects and in 16 PD patients with more than 5 years duration of disease, using a 3T MRI scanner and a constrained spherical deconvolution (CSD) approach for tractographic reconstructions. In addition, we performed statistical analysis of DTI parameters and fractional anisotropy (FA) XYZ direction samplings. We found a statistically significant decrement of FA values in PD patients compared to controls (p < 0.05). In addition, extrapolating and analyzing FA XYZ direction samplings for each patient and each control, we found that this result was due to a stronger decrement of FA values along the Y axis (antero-posterior direction) (p < 0.01); FA changes along X and Z axes were not statistically significant (p > 0.05). We confirmed also no statistically significant differences of FA and apparent diffusion coefficient (ADC) for cerebellar peduncles in PD patients compared to healthy controls. The DTI-based cerebellar abnormalities in PD could constitute an advance in the knowledge of this disease. We demonstrated a statistically significant reduction of FA in cerebellar hemispheres of PD patients compared to healthy controls. Our work also demonstrated that the use of more sophisticated approaches in the DTI parameter analysis could potentially have a clinical relevance. (orig.)

  10. Optimising polarised neutron scattering measurements--XYZ and polarimetry analysis

    International Nuclear Information System (INIS)

    Cussen, L.D.; Goossens, D.J.

    2002-01-01

    The analytic optimisation of neutron scattering measurements made using XYZ polarisation analysis and neutron polarimetry techniques is discussed. Expressions for the 'quality factor' and the optimum division of counting time for the XYZ technique are presented. For neutron polarimetry the optimisation is identified as analogous to that for measuring the flipping ratio and reference is made to the results already in the literature

  11. Optimising polarised neutron scattering measurements--XYZ and polarimetry analysis

    CERN Document Server

    Cussen, L D

    2002-01-01

    The analytic optimisation of neutron scattering measurements made using XYZ polarisation analysis and neutron polarimetry techniques is discussed. Expressions for the 'quality factor' and the optimum division of counting time for the XYZ technique are presented. For neutron polarimetry the optimisation is identified as analogous to that for measuring the flipping ratio and reference is made to the results already in the literature.

  12. Application of ant colony optimisation in distribution transformer sizing

    African Journals Online (AJOL)

    This study proposes an optimisation method for transformer sizing in power system using ant colony optimisation and a verification of the process by MATLAB software. The aim is to address the issue of transformer sizing which is a major challenge affecting its effective performance, longevity, huge capital cost and power ...

  13. Multi-objective evolutionary optimisation for product design and manufacturing

    CERN Document Server

    2011-01-01

    Presents state-of-the-art research in the area of multi-objective evolutionary optimisation for integrated product design and manufacturing Provides a comprehensive review of the literature Gives in-depth descriptions of recently developed innovative and novel methodologies, algorithms and systems in the area of modelling, simulation and optimisation

  14. DACIA LOGAN LIVE AXLE OPTIMISATION USING COMPUTER GRAPHICS

    Directory of Open Access Journals (Sweden)

    KIRALY Andrei

    2017-05-01

    Full Text Available The paper presents some contributions to the calculus and optimisation of a live axle used at Dacia Logan using computer graphics software for creating the model and afterwards using FEA evaluation to determine the effectiveness of the optimisation. Thus using specialized computer software, a simulation is made and the results were compared to the measured real prototype.

  15. Spatial-structural interaction and strain energy structural optimisation

    NARCIS (Netherlands)

    Hofmeyer, H.; Davila Delgado, J.M.; Borrmann, A.; Geyer, P.; Rafiq, Y.; Wilde, de P.

    2012-01-01

    A research engine iteratively transforms spatial designs into structural designs and vice versa. Furthermore, spatial and structural designs are optimised. It is suggested to optimise a structural design by evaluating the strain energy of its elements and by then removing, adding, or changing the

  16. Optimising of Steel Fiber Reinforced Concrete Mix Design | Beddar ...

    African Journals Online (AJOL)

    Optimising of Steel Fiber Reinforced Concrete Mix Design. ... as a result of the loss of mixture workability that will be translated into a difficult concrete casting in site. ... An experimental study of an optimisation method of fibres in reinforced ...

  17. GAOS: Spatial optimisation of crop and nature within agricultural fields

    NARCIS (Netherlands)

    Bruin, de S.; Janssen, H.; Klompe, A.; Lerink, P.; Vanmeulebrouk, B.

    2010-01-01

    This paper proposes and demonstrates a spatial optimiser that allocates areas of inefficient machine manoeuvring to field margins thus improving the use of available space and supporting map-based Controlled Traffic Farming. A prototype web service (GAOS) allows farmers to optimise tracks within

  18. Dose to population as a metric in the design of optimised exposure control in digital mammography

    International Nuclear Information System (INIS)

    Klausz, R.; Shramchenko, N.

    2005-01-01

    This paper describes a methods for automatic optimisation of parameter (AOP) in digital mammography systems. Using a model of the image chain, contrast to noise ratio (CNR) and average glandular dose (AGD) are computed for possible X-ray parameters and breast types. The optimisation process consists of the determination of the operating points providing the lowest possible AGD for each CNR level and breast type. The proposed metric for the dose used in the design of an AOP mode is the resulting dose to the population, computed by averaging the AGD values over the distribution of breast types in the population. This method has been applied to the automatic exposure control of new digital mammography equipment. Breast thickness and composition are estimated from a low dose pre-exposure and used to index tables containing sets of optimised operating points. The resulting average dose to the population ranges from a level comparable to state-of-the-art screen/film mammography to a reduction by a factor of two. Using this method, both CNR and dose are kept under control for all breast types, taking into consideration both individual and collective risk. (authors)

  19. Methodology implementation for multi objective optimisation for nuclear fleet evolution scenarios

    International Nuclear Information System (INIS)

    Freynet, David

    2016-01-01

    The issue of the evolution French nuclear fleet can be considered through the study of nuclear transition scenarios. These studies are of paramount importance as their results can greatly affect the decision making process, given that they take into account industrial concerns, investments, time, and nuclear system complexity. Such studies can be performed with the COSI code (developed at the CEA/DEN), which enables the calculation of matter inventories and fluxes across the fuel cycle (nuclear reactors and associated facilities), especially when coupled with the CESAR depletion code. The studies today performed with COSI require the definition of the various scenarios' input parameters, in order to fulfil different objectives such as minimising natural uranium consumption, waste production and so on. These parameters concern the quantities and the scheduling of spent fuel destined for reprocessing, and the number, the type and the commissioning dates of deployed reactors.This work aims to develop, validate and apply an optimisation methodology coupled with COSI, in order to determine optimal nuclear transition scenarios for a multi-objective platform. Firstly, this methodology is based on the acceleration of scenario evaluation, enabling the use of optimisation methods in a reasonable time-frame. With this goal in mind, artificial neural network irradiation surrogate models are created with the URANIE platform (developed at the CEA/DEN) and are implemented within COSI. The next step in this work is to use, adapt and compare different optimisation methods, such as URANIE's genetic algorithm and particle swarm methods, in order to define a methodology suited to this type of study. This methodology development is based on an incremental approach which progressively adds objectives, constraints and decision variables to the optimisation problem definition. The variables added, which are related to reactor deployment and spent fuel reprocessing strategies, are chosen

  20. Modified cuckoo search: A new gradient free optimisation algorithm

    International Nuclear Information System (INIS)

    Walton, S.; Hassan, O.; Morgan, K.; Brown, M.R.

    2011-01-01

    Highlights: → Modified cuckoo search (MCS) is a new gradient free optimisation algorithm. → MCS shows a high convergence rate, able to outperform other optimisers. → MCS is particularly strong at high dimension objective functions. → MCS performs well when applied to engineering problems. - Abstract: A new robust optimisation algorithm, which can be regarded as a modification of the recently developed cuckoo search, is presented. The modification involves the addition of information exchange between the top eggs, or the best solutions. Standard optimisation benchmarking functions are used to test the effects of these modifications and it is demonstrated that, in most cases, the modified cuckoo search performs as well as, or better than, the standard cuckoo search, a particle swarm optimiser, and a differential evolution strategy. In particular the modified cuckoo search shows a high convergence rate to the true global minimum even at high numbers of dimensions.

  1. Results of the 2010 IGSC Topical Session on Optimisation

    International Nuclear Information System (INIS)

    Bailey, Lucy

    2014-01-01

    Document available in abstract form only. Full text follows: The 2010 IGSC topical session on optimisation explored a wide range of issues concerning optimisation throughout the radioactive waste management process. Philosophical and ethical questions were discussed, such as: - To what extent is the process of optimisation more important than the end result? - How do we balance long-term environmental safety with near-term operational safety? - For how long should options be kept open? - In balancing safety and excessive cost, when is BAT achieved and who decides on this? * How should we balance the needs of current society with those of future generations? It was clear that optimisation is about getting the right balance between a range of issues that cover: radiation protection, environmental protection, operational safety, operational requirements, social expectations and cost. The optimisation process will also need to respect various constraints, which are likely to include: regulatory requirements, site restrictions, community-imposed requirements or restrictions and resource constraints. These issues were explored through a number of presentations that discussed practical cases of optimisation occurring at different stages of international radioactive waste management programmes. These covered: - Operations and decommissioning - management of large disused components, from the findings of an international study, presented by WPDD; - Concept option selection, prior to site selection - upstream and disposal system optioneering in the UK; - Siting decisions - examples from both Germany and France, explaining how optimisation is being used to support site comparisons and communicate siting decisions; - Repository design decisions - comparison of KBS-3 horizontal and vertical deposition options in Finland; and - On-going optimisation during repository operation - operational experience from WIPP in the US. The variety of the remarks and views expressed during the

  2. Work management to optimise occupational radiological protection

    International Nuclear Information System (INIS)

    Ahier, B.

    2009-01-01

    Although work management is no longer a new concept, continued efforts are still needed to ensure that good performance, outcomes and trends are maintained in the face of current and future challenges. The ISOE programme thus created an Expert Group on Work Management in 2007 to develop an updated report reflecting the current state of knowledge, technology and experience in the occupational radiological protection of workers at nuclear power plants. Published in 2009, the new ISOE report on Work Management to Optimise Occupational Radiological Protection in the Nuclear Power Industry provides up-to-date practical guidance on the application of work management principles. Work management measures aim at optimising occupational radiological protection in the context of the economic viability of the installation. Important factors in this respect are measures and techniques influencing i) dose and dose rate, including source- term reduction; ii) exposure, including amount of time spent in controlled areas for operations; and iii) efficiency in short- and long-term planning, worker involvement, coordination and training. Equally important due to their broad, cross-cutting nature are the motivational and organisational arrangements adopted. The responsibility for these aspects may reside in various parts of an installation's organisational structure, and thus, a multi-disciplinary approach must be recognised, accounted for and well-integrated in any work. Based on the operational experience within the ISOE programme, the following key areas of work management have been identified: - regulatory aspects; - ALARA management policy; - worker involvement and performance; - work planning and scheduling; - work preparation; - work implementation; - work assessment and feedback; - ensuring continuous improvement. The details of each of these areas are elaborated and illustrated in the report through examples and case studies arising from ISOE experience. They are intended to

  3. Control strategies to optimise power output in heave buoy energy convertors

    International Nuclear Information System (INIS)

    Abu Zarim, M A U A; Sharip, R M

    2013-01-01

    Wave energy converter (WEC) designs are always discussed in order to obtain an optimum design to generate the power from the wave. Output power from wave energy converter can be improved by controlling the oscillation in order to acquire the interaction between the WEC and the incident wave.The purpose of this research is to study the heave buoys in the interest to generate an optimum power output by optimising the phase control and amplitude in order to maximise the active power. In line with the real aims of this study which investigate the theory and function and hence optimise the power generation of heave buoys as renewable energy sources, the condition that influence the heave buoy must be understand in which to propose the control strategies that can be use to control parameters to obtain optimum power output. However, this research is in an early stage, and further analysis and technical development is require

  4. Lost in Optimisation of Water Distribution Systems? A Literature Review of System Design

    Directory of Open Access Journals (Sweden)

    Helena Mala-Jetmarova

    2018-03-01

    Full Text Available Optimisation of water distribution system design is a well-established research field, which has been extremely productive since the end of the 1980s. Its primary focus is to minimise the cost of a proposed pipe network infrastructure. This paper reviews in a systematic manner articles published over the past three decades, which are relevant to the design of new water distribution systems, and the strengthening, expansion and rehabilitation of existing water distribution systems, inclusive of design timing, parameter uncertainty, water quality, and operational considerations. It identifies trends and limits in the field, and provides future research directions. Exclusively, this review paper also contains comprehensive information from over one hundred and twenty publications in a tabular form, including optimisation model formulations, solution methodologies used, and other important details.

  5. Optimisation of a wet FGD pilot plant using fine limestone and organic acids

    DEFF Research Database (Denmark)

    Frandsen, Jan; Kiil, Søren; Johnsson, Jan Erik

    2001-01-01

    , but the residual limestone content in the gypsum increased to somewhere between 19 and 30 wt%, making this pH range unsuitable for use in a full-scale plant. The investigations have shown that both the addition of organic acids and the use of a limestone with a fine PSD can be used to optimise wet FGD plants. (C......The effects of adding an organic acid or using a limestone with a fine particle size distribution (PSD) have been examined in a wet flue gas desulphurisation (FGD) pilot plant. Optimisation of the plant with respect to the degree of desulphurisation and the residual limestone content of the gypsum...... has been the aim of the work. In contrast to earlier investigations with organic acids, all essential process parameters (i.e. gas phase concentration profiles of SO(2), slurry pH profiles. and residual limestone in the gypsum) were considered. Slurry concentrations of adipic acid in the range of 0...

  6. COMPLIANCE ANALYSIS, OPTIMISATION AND COMPARISON OF A NEW 3PUS-PU MECHANISM

    Directory of Open Access Journals (Sweden)

    B. Wei

    2013-06-01

    Full Text Available This paper investigates the compliance of a new 3PUS-PU hybrid mechanism with three degrees of freedom, including translation along the Z axis and rotations about the X and Y axes. Firstly, the kinematic analysis of the mechanism is analysed and the compliance model of the mechanism derived. Secondly, the effects the geometric parameters and position and orientation parameters on the compliance of the mechanism in each direction are investigated, and the genetic algorithm is used to optimise the global compliance by simultaneously adjusting design variables. Finally, the compliance of two similar kinds of 3PUS-PU mechanism in each direction is reviewed.

  7. A comparison of forward planning and optimised inverse planning

    International Nuclear Information System (INIS)

    Oldham, Mark; Neal, Anthony; Webb, Steve

    1995-01-01

    A radiotherapy treatment plan optimisation algorithm has been applied to 48 prostate plans and the results compared with those of an experienced human planner. Twelve patients were used in the study, and a 3, 4, 6 and 8 field plan (with standard coplanar beam angles for each plan type) were optimised by both the human planner and the optimisation algorithm. The human planner 'optimised' the plan by conventional forward planning techniques. The optimisation algorithm was based on fast-simulated-annealing. 'Importance factors' assigned to different regions of the patient provide a method for controlling the algorithm, and it was found that the same values gave good results for almost all plans. The plans were compared on the basis of dose statistics and normal-tissue-complication-probability (NTCP) and tumour-control-probability (TCP). The results show that the optimisation algorithm yielded results that were at least as good as the human planner for all plan types, and on the whole slightly better. A study of the beam-weights chosen by the optimisation algorithm and the planner will be presented. The optimisation algorithm showed greater variation, in response to individual patient geometry. For simple (e.g. 3 field) plans it was found to consistently achieve slightly higher TCP and lower NTCP values. For more complicated (e.g. 8 fields) plans the optimisation also achieved slightly better results with generally less numbers of beams. The optimisation time was always ≤5 minutes; a factor of up to 20 times faster than the human planner

  8. Automatic optimisation of gamma dose rate sensor networks: The DETECT Optimisation Tool

    DEFF Research Database (Denmark)

    Helle, K.B.; Müller, T.O.; Astrup, Poul

    2014-01-01

    of the EU FP 7 project DETECT. It evaluates the gamma dose rates that a proposed set of sensors might measure in an emergency and uses this information to optimise the sensor locations. The gamma dose rates are taken from a comprehensive library of simulations of atmospheric radioactive plumes from 64......Fast delivery of comprehensive information on the radiological situation is essential for decision-making in nuclear emergencies. Most national radiological agencies in Europe employ gamma dose rate sensor networks to monitor radioactive pollution of the atmosphere. Sensor locations were often...... source locations. These simulations cover the whole European Union, so the DOT allows evaluation and optimisation of sensor networks for all EU countries, as well as evaluation of fencing sensors around possible sources. Users can choose from seven cost functions to evaluate the capability of a given...

  9. VEHICLE DRIVING CYCLE OPTIMISATION ON THE HIGHWAY

    Directory of Open Access Journals (Sweden)

    Zinoviy STOTSKO

    2016-06-01

    Full Text Available This paper is devoted to the problem of reducing vehicle energy consumption. The authors consider the optimisation of highway driving cycle a way to use the kinetic energy of a car more effectively at various road conditions. The model of a vehicle driving control at the highway which consists of elementary cycles, such as accelerating, free rolling and deceleration under forces of external resistance, was designed. Braking, as an energy dissipation regime, was not included. The influence of the various longitudinal profiles of the road was taken into consideration and included in the model. Ways to use the results of monitoring road and traffic conditions are presented. The method of non-linear programming is used to design the optimal vehicle control function and phase trajectory. The results are presented by improved typical driving cycles that present energy saving as a subject of choice at a specified schedule.

  10. Optimisation algorithms for ECG data compression.

    Science.gov (United States)

    Haugland, D; Heber, J G; Husøy, J H

    1997-07-01

    The use of exact optimisation algorithms for compressing digital electrocardiograms (ECGs) is demonstrated. As opposed to traditional time-domain methods, which use heuristics to select a small subset of representative signal samples, the problem of selecting the subset is formulated in rigorous mathematical terms. This approach makes it possible to derive algorithms guaranteeing the smallest possible reconstruction error when a bounded selection of signal samples is interpolated. The proposed model resembles well-known network models and is solved by a cubic dynamic programming algorithm. When applied to standard test problems, the algorithm produces a compressed representation for which the distortion is about one-half of that obtained by traditional time-domain compression techniques at reasonable compression ratios. This illustrates that, in terms of the accuracy of decoded signals, existing time-domain heuristics for ECG compression may be far from what is theoretically achievable. The paper is an attempt to bridge this gap.

  11. Optimisation and constraints - a view from ICRP

    International Nuclear Information System (INIS)

    Dunster, H.J.

    1994-01-01

    The optimisation of protection has been the major policy underlying the recommendations of the International Commission on Radiological Protection for more than 20 years. In earlier forms, the concept can be traced back to 1951. Constraints are more recent, appearing in their present form only in the 1990 recommendations of the Commission. The requirement to keep all exposures as low as reasonably achievable applies to both normal and potential exposures. The policy and the techniques are well established for normal exposures, i.e. exposures that are certain to occur. The application to potential exposures, i.e. exposures that have a probability of occurring that is less than unity, is more difficult and is still under international discussion. Constraints are needed to limit the inequity associated with the use of collective dose in cost-benefit analysis and to provide a margin to protect individuals who may be exposed to more than one source. (author)

  12. Optimising Impact in Astronomy for Development Projects

    Science.gov (United States)

    Grant, Eli

    2015-08-01

    Positive outcomes in the fields of science education and international development are notoriously difficult to achieve. Among the challenges facing projects that use astronomy to improve education and socio-economic development is how to optimise project design in order to achieve the greatest possible benefits. Over the past century, medical scientists along with statisticians and economists have progressed an increasingly sophisticated and scientific approach to designing, testing and improving social intervention and public health education strategies. This talk offers a brief review of the history and current state of `intervention science'. A similar framework is then proposed for astronomy outreach and education projects, with applied examples given of how existing evidence can be used to inform project design, predict and estimate cost-effectiveness, minimise the risk of unintended negative consequences and increase the likelihood of target outcomes being achieved.

  13. Public transport optimisation emphasising passengers’ travel behaviour

    DEFF Research Database (Denmark)

    Jensen, Jens Parbo

    to the case where the two problems are solved sequentially without taking into account interdependencies. Figure 1 - Planning public transport The PhD study develops a metaheuristic algorithm to adapt the line plan configuration in order better to match passengers’ travel demand in terms of transfers as well......Passengers in public transport complaining about their travel experiences are not uncommon. This might seem counterintuitive since several operators worldwide are presenting better key performance indicators year by year. The present PhD study focuses on developing optimisation algorithms...... to enhance the operations of public transport while explicitly emphasising passengers’ travel behaviour and preferences. Similar to economic theory, interactions between supply and demand are omnipresent in the context of public transport operations. In public transport, the demand is represented...

  14. Value Chain Optimisation of Biogas Production

    DEFF Research Database (Denmark)

    Jensen, Ida Græsted

    economically feasible. In this PhD thesis, the focus is to create models for investigating the profitability of biogas projects by: 1) including the whole value chain in a mathematical model and considering mass and energy changes on the upstream part of the chain; and 2) including profit allocation in a value......, the costs on the biogas plant has been included in the model using economy of scale. For the second point, a mathematical model considering profit allocation was developed applying three allocation mechanisms. This mathematical model can be applied as a second step after the value chain optimisation. After...... in the energy systems model to find the optimal end use of each type of gas and fuel. The main contributions of this thesis are the methods developed on plant level. Both the mathematical model for the value chain and the profit allocation model can be generalised and used in other industries where mass...

  15. Expect systems and optimisation in process control

    Energy Technology Data Exchange (ETDEWEB)

    Mamdani, A.; Efstathiou, J. (eds.)

    1986-01-01

    This report brings together recent developments both in expert systems and in optimisation, and deals with current applications in industry. Part One is concerned with Artificial Intellegence in planning and scheduling and with rule-based control implementation. The tasks of control maintenance, rescheduling and planning are each discussed in relation to new theoretical developments, techniques available, and sample applications. Part Two covers model based control techniques in which the control decisions are used in a computer model of the process. Fault diagnosis, maintenance and trouble-shooting are just some of the activities covered. Part Three contains case studies of projects currently in progress, giving details of the software available and the likely future trends. One of these, on qualitative plant modelling as a basis for knowledge-based operator aids in nuclear power stations is indexed separately.

  16. Expert systems and optimisation in process control

    International Nuclear Information System (INIS)

    Mamdani, A.; Efstathiou, J.

    1986-01-01

    This report brings together recent developments both in expert systems and in optimisation, and deals with current applications in industry. Part One is concerned with Artificial Intellegence in planning and scheduling and with rule-based control implementation. The tasks of control maintenance, rescheduling and planning are each discussed in relation to new theoretical developments, techniques available, and sample applications. Part Two covers model based control techniques in which the control decisions are used in a computer model of the process. Fault diagnosis, maintenance and trouble-shooting are just some of the activities covered. Part Three contains case studies of projects currently in progress, giving details of the software available and the likely future trends. One of these, on qualitative plant modelling as a basis for knowledge-based operator aids in nuclear power stations is indexed separately. (author)

  17. Improving and optimising road pricing in Copenhagen

    DEFF Research Database (Denmark)

    Nielsen, Otto Anker; Larsen, Marie Karen

    2008-01-01

    though quite a number of proposed charging systems have been examined only a few pricing strategies have been investigated. This paper deals with the optimisation of different designs for a road pricing system in the Greater Copenhagen area with respect to temporal and spatial differentiation......The question whether to introduce toll rings or road pricing in Copenhagen has been discussed intensively during the last 10 years. The main results of previous analyses are that none of the systems would make a positive contribution at present, when considered from a socio-economic view. Even...... of the pricing levels. A detailed transport model was used to describe the demand effects. The model was based on data from a real test of road pricing on 500 car drivers. The paper compares the price systems with regard to traffic effects and generalised costs for users and society. It is shown how important...

  18. Optimising Signalised Intersection Using Wireless Vehicle Detectors

    DEFF Research Database (Denmark)

    Adjin, Daniel Michael Okwabi; Torkudzor, Moses; Asare, Jack

    Traffic congestion on roads wastes travel times. In this paper, we developed a vehicular traffic model to optimise a signalised intersection in Accra, using wireless vehicle detectors. Traffic volume gathered was extrapolated to cover 2011 and 2016 and were analysed to obtain the peak hour traffic...... volume causing congestion. The intersection was modelled and simulated in Synchro7 as an actuated signalised model using results from the analysed data. The model for morning peak periods gave optimal cycle lengths of 100s and 150s with corresponding intersection delay of 48.9s and 90.6s in 2011 and 2016...... respectively while that for the evening was 55s giving delay of 14.2s and 16.3s respectively. It is shown that the model will improve traffic flow at the intersection....

  19. Dynamic optimisation of an industrial web process

    Directory of Open Access Journals (Sweden)

    M Soufian

    2008-09-01

    Full Text Available An industrial web process has been studied and it is shown that theunderlying physics of such processes governs by the Navier-Stokes partialdifferential equations with moving boundary conditions, which in turn have tobe determined by the solution of the thermodynamics equations. Thedevelopment of a two-dimensional continuous-discrete model structurebased on this study is presented. Other models are constructed based onthis model for better identification and optimisation purposes. Theparameters of the proposed models are then estimated using real dataobtained from the identification experiments with the process plant. Varioussimulation tests for validation are accompanied with the design, developmentand real-time industrial implementation of an optimal controller for dynamicoptimisation of this web process. It is shown that in comparison with thetraditional controller, the new controller resulted in a better performance, animprovement in film quality and saving in raw materials. This demonstrates theefficiency and validation of the developed models.

  20. Recent perspectives on optimisation of radiological protection

    International Nuclear Information System (INIS)

    Robb, J.D.; Croft, J.R.

    1992-01-01

    The ALARA principle as a requirement in radiological protection has evolved from its theoretical roots. Based on several years work, this paper provides a backdrop to practical approaches to ALARA for the 1990s. The key step, developing ALARA thinking so that it becomes an integral part of radiological protection programmes, is discussed using examples from the UK and France, as is the role of tools to help standardise judgements for decision-making. In its latest recommendations, ICRP have suggested that the optimisation of protection should be constrained by restrictions on the doses to individuals. This paper also considers the function of such restrictions for occupational, public and medical exposure, and in the design process. (author)

  1. Optimisation of Inulinase Production by Kluyveromyces bulgaricus

    Directory of Open Access Journals (Sweden)

    Darija Vranešić

    2002-01-01

    Full Text Available The present work is based on observation of the effects of pH and temperature of fermentation on the production of microbial enzyme inulinase by Kluyveromyces marxianus var. bulgaricus. Inulinase hydrolyzes inulin, a polysaccharide which can be isolated from plants such as Jerusalem artichoke, chicory or dahlia, and transformed into pure fructose or fructooligosaccharides. Fructooligosaccharides have great potential in food industry because they can be used as calorie-reduced compounds and noncariogenic sweeteners as well as soluble fibre and prebiotic compounds. Fructose formation from inulin is a single step enzymatic reaction and yields are up to 95 % the fructose. On the contrary, conventional fructose production from starch needs at least three enzymatic steps, yielding only 45 % of fructose. The process of inulinase production was optimised by using experimental design method. pH value of the cultivation medium showed to be the most significant variable and it should be maintained at optimum value of 3.6. The effect of temperature was slightly lower and optimal values were between 30 and 33 °C. At a low pH value of the cultivation medium, the microorganism was not able to producem enough enzyme and enzyme activities were low. Similar effect was caused by high temperature. The highest values of enzyme activities were achieved at optimal fermentation conditions and the values were: 100.16–124.36 IU/mL (with sucrose as substrate for determination of enzyme activity or 8.6–11.6 IU/mL (with inulin as substrate, respectively. The method of factorial design and response surface analysis makes it possible to study several factors simultaneously, to quantify the individual effect of each factor and to investigate their possible interactions. As a comparison to this method, optimisation of a physiological enzyme activity model depending on pH and temperature was also studied.

  2. Integration of BOLD-fMRI and DTI into radiation treatment planning for high-grade gliomas located near the primary motor cortexes and corticospinal tracts

    International Nuclear Information System (INIS)

    Wang, Minglei; Ma, Hui; Wang, Xiaodong; Guo, Yanhong; Xia, Xinshe; Xia, Hechun; Guo, Yulin; Huang, Xueying; He, Hong; Jia, Xiaoxiong; Xie, Yan

    2015-01-01

    The main objective of this study was to evaluate the efficacy of integrating the blood oxygen level dependent functional magnetic resonance imaging (BOLD-fMRI) and diffusion tensor imaging (DTI) data into radiation treatment planning for high-grade gliomas located near the primary motor cortexes (PMCs) and corticospinal tracts (CSTs). A total of 20 patients with high-grade gliomas adjacent to PMCs and CSTs between 2012 and 2014 were recruited. The bilateral PMCs and CSTs were located in the normal regions without any overlapping with target volume of the lesions. BOLD-fMRI, DTI and conventional MRI were performed on patients (Karnofsky performance score ≥ 70) before radical radiotherapy treatment. Four different imaging studies were conducted in each patient: a planning computed tomography (CT), an anatomical MRI, a DTI and a BOLD-fMRI. For each case, three treatment plans (3DCRT, IMRT and IMRT-PMC&CST) were developed by 3 different physicists using the Pinnacle planning system. Our study has shown that there was no significant difference between the 3DCRT and IMRT plans in terms of dose homogeneity, but IMRT displayed better planning target volume (PTV) dose conformity. In addition, we have found that the Dmax and Dmean to the ipsilateral and contralateral PMC and CST regions were considerably decreased in IMRT-PMC&CST group (p < 0.001). In conclusion, integration of BOLD-fMRI and DTI into radiation treatment planning is feasible and beneficial. With the assistance of the above-described techniques, the bilateral PMCs and CSTs adjacent to the target volume could be clearly marked as OARs and spared during treatment

  3. Pre-surgical integration of FMRI and DTI of the sensorimotor system in transcortical resection of a high-grade insular astrocytoma

    Directory of Open Access Journals (Sweden)

    Chelsea eEkstrand

    2016-03-01

    Full Text Available Herein we report on a patient with a WHO Grade III astrocytoma in the right insular region in close proximity to the internal capsule who underwent a right frontotemporal craniotomy. Total gross resection of insular gliomas remains surgically challenging based on the possibility of damage to the corticospinal tracts. However, maximizing the extent of resection has been shown to decrease future adverse outcomes. Thus, the goal of such surgeries should focus on maximizing extent of resection while minimizing possible adverse outcomes. In this case, pre-surgical planning included integration of functional magnetic resonance imaging (fMRI and diffusion tensor imaging (DTI, to localize motor and sensory pathways. Novel fMRI tasks were individually developed for the patient to maximize both somatosensory and motor activation simultaneously in areas in close proximity to the tumor. Information obtained was used to optimize resection trajectory and extent, facilitating gross total resection of the astrocytoma. Across all three motor-sensory tasks administered, fMRI revealed an area of interest just superior and lateral to the astrocytoma. Further, DTI analyses showed displacement of the corona radiata around the superior dorsal surface of the astrocytoma, extending in the direction of the activation found using fMRI. Taking into account these results, a transcortical superior temporal gyrus surgical approach was chosen in order to avoid the area of interest identified by fMRI and DTI. Total gross resection was achieved and minor post-surgical motor and sensory deficits were temporary. This case highlights the utility of comprehensive pre-surgical planning, including fMRI and DTI, to maximize surgical outcomes on a case-by-case basis.

  4. Probabilistic sensitivity analysis of optimised preventive maintenance strategies for deteriorating infrastructure assets

    International Nuclear Information System (INIS)

    Daneshkhah, A.; Stocks, N.G.; Jeffrey, P.

    2017-01-01

    Efficient life-cycle management of civil infrastructure systems under continuous deterioration can be improved by studying the sensitivity of optimised preventive maintenance decisions with respect to changes in model parameters. Sensitivity analysis in maintenance optimisation problems is important because if the calculation of the cost of preventive maintenance strategies is not sufficiently robust, the use of the maintenance model can generate optimised maintenances strategies that are not cost-effective. Probabilistic sensitivity analysis methods (particularly variance based ones), only partially respond to this issue and their use is limited to evaluating the extent to which uncertainty in each input contributes to the overall output's variance. These methods do not take account of the decision-making problem in a straightforward manner. To address this issue, we use the concept of the Expected Value of Perfect Information (EVPI) to perform decision-informed sensitivity analysis: to identify the key parameters of the problem and quantify the value of learning about certain aspects of the life-cycle management of civil infrastructure system. This approach allows us to quantify the benefits of the maintenance strategies in terms of expected costs and in the light of accumulated information about the model parameters and aspects of the system, such as the ageing process. We use a Gamma process model to represent the uncertainty associated with asset deterioration, illustrating the use of EVPI to perform sensitivity analysis on the optimisation problem for age-based and condition-based preventive maintenance strategies. The evaluation of EVPI indices is computationally demanding and Markov Chain Monte Carlo techniques would not be helpful. To overcome this computational difficulty, we approximate the EVPI indices using Gaussian process emulators. The implications of the worked numerical examples discussed in the context of analytical efficiency and organisational

  5. Rat brain digital stereotaxic white matter atlas with fine tract delineation in Paxinos space and its automated applications in DTI data analysis.

    Science.gov (United States)

    Liang, Shengxiang; Wu, Shang; Huang, Qi; Duan, Shaofeng; Liu, Hua; Li, Yuxiao; Zhao, Shujun; Nie, Binbin; Shan, Baoci

    2017-11-01

    To automatically analyze diffusion tensor images of the rat brain via both voxel-based and ROI-based approaches, we constructed a new white matter atlas of the rat brain with fine tracts delineation in the Paxinos and Watson space. Unlike in previous studies, we constructed a digital atlas image from the latest edition of the Paxinos and Watson. This atlas contains 111 carefully delineated white matter fibers. A white matter network of rat brain based on anatomy was constructed by locating the intersection of all these tracts and recording the nuclei on the pathway of each white matter tract. Moreover, a compatible rat brain template from DTI images was created and standardized into the atlas space. To evaluate the automated application of the atlas in DTI data analysis, a group of rats with right-side middle cerebral artery occlusion (MCAO) and those without were enrolled in this study. The voxel-based analysis result shows that the brain region showing significant declines in signal in the MCAO rats was consistent with the occlusion position. We constructed a stereotaxic white matter atlas of the rat brain with fine tract delineation and a compatible template for the data analysis of DTI images of the rat brain. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Correlation of force control with regional spinal DTI in patients with cervical spondylosis without signs of spinal cord injury on conventional MRI

    International Nuclear Information System (INIS)

    Lindberg, Paavel G.; Sanchez, Katherine; Rannou, Francois; Poiraudeau, Serge; Ozcan, Fidan; Feydy, Antoine; Maier, Marc A.

    2016-01-01

    The aim of this study was to investigate spinal cord structure in patients with cervical spondylosis where conventional MRI fails to reveal spinal cord damage. We performed a cross-sectional study of patients with cervical spondylosis without conventional MRI findings of spinal cord damage and healthy controls. Subjects were studied using spinal diffusion tensor imaging (DTI), precision grip and foot force-tracking tasks, and a clinical examination including assessment of neurological signs. A regional analysis of lateral and medial spinal white matter across multiple cervical levels (C1-C5) was performed. DTI revealed reduced fractional anisotropy (FA) and increased radial diffusivity (RD) in the lateral spinal cord at the level of greatest compression (lowest Pavlov ratio) in patients (p < 0.05). Patients with spondylosis had greater error and longer release duration in both grip and foot force-tracking. Similar spinal cord deficits were present in patients without neurological signs. Increased error in grip and foot tracking (low accuracy) correlated with increased RD in the lateral spinal cord at the level of greatest compression (p ≤ 0.01). Spinal DTI can detect subtle spinal cord damage of functional relevance in cervical spondylosis, even in patients without signs on conventional T2-imaging and without neurological signs. (orig.)

  7. Correlation of force control with regional spinal DTI in patients with cervical spondylosis without signs of spinal cord injury on conventional MRI

    Energy Technology Data Exchange (ETDEWEB)

    Lindberg, Paavel G. [Universite Paris Descartes, Sorbonne Paris Cite, FR 3636 Neurosciences, Paris (France); Centre de Psychiatrie et Neurosciences, Inserm U894, Paris (France); Universite Paris Descartes, Sorbonne Paris Cite, Paris (France); Universite Paris Descartes, Service de Radiologie B, APHP, CHU Cochin, Faculte de Medecine, Paris (France); Sanchez, Katherine; Rannou, Francois; Poiraudeau, Serge [Universite Paris Descartes, Sorbonne Paris Cite, Paris (France); Service de Medecine Physique et de Readaptation, APHP, CHU Cochin, Paris (France); INSERM U1153 Epidemiologie Clinique des Maladies Osteo-Articulaires, Paris (France); Ozcan, Fidan [Universite Paris Descartes, Sorbonne Paris Cite, FR 3636 Neurosciences, Paris (France); Feydy, Antoine [Universite Paris Descartes, Sorbonne Paris Cite, FR 3636 Neurosciences, Paris (France); Universite Paris Descartes, Sorbonne Paris Cite, Paris (France); Universite Paris Descartes, Service de Radiologie B, APHP, CHU Cochin, Faculte de Medecine, Paris (France); Maier, Marc A. [Universite Paris Descartes, Sorbonne Paris Cite, FR 3636 Neurosciences, Paris (France); Universite Paris Descartes, Sorbonne Paris Cite, Paris (France); Universite Paris Diderot, Sorbonne Paris Cite, Paris (France)

    2016-03-15

    The aim of this study was to investigate spinal cord structure in patients with cervical spondylosis where conventional MRI fails to reveal spinal cord damage. We performed a cross-sectional study of patients with cervical spondylosis without conventional MRI findings of spinal cord damage and healthy controls. Subjects were studied using spinal diffusion tensor imaging (DTI), precision grip and foot force-tracking tasks, and a clinical examination including assessment of neurological signs. A regional analysis of lateral and medial spinal white matter across multiple cervical levels (C1-C5) was performed. DTI revealed reduced fractional anisotropy (FA) and increased radial diffusivity (RD) in the lateral spinal cord at the level of greatest compression (lowest Pavlov ratio) in patients (p < 0.05). Patients with spondylosis had greater error and longer release duration in both grip and foot force-tracking. Similar spinal cord deficits were present in patients without neurological signs. Increased error in grip and foot tracking (low accuracy) correlated with increased RD in the lateral spinal cord at the level of greatest compression (p ≤ 0.01). Spinal DTI can detect subtle spinal cord damage of functional relevance in cervical spondylosis, even in patients without signs on conventional T2-imaging and without neurological signs. (orig.)

  8. Design optimisation of a flywheel hybrid vehicle

    Energy Technology Data Exchange (ETDEWEB)

    Kok, D.B.

    1999-11-04

    This thesis describes the design optimisation of a flywheel hybrid vehicle with respect to fuel consumption and exhaust gas emissions. The driveline of this passenger car uses two power sources: a small spark ignition internal combustion engine with three-way catalyst, and a highspeed flywheel system for kinetic energy storage. A custom-made continuously variable transmission (CVT) with so-called i{sup 2} control transports energy between these power sources and the vehicle wheels. The driveline includes auxiliary systems for hydraulic, vacuum and electric purposes. In this fully mechanical driveline, parasitic energy losses determine the vehicle's fuel saving potential to a large extent. Practicable energy loss models have been derived to quantify friction losses in bearings, gearwheels, the CVT, clutches and dynamic seals. In addition, the aerodynamic drag in the flywheel system and power consumption of auxiliaries are charted. With the energy loss models available, a calculation procedure is introduced to optimise the flywheel as a subsystem in which the rotor geometry, the safety containment, and the vacuum system are designed for minimum energy use within the context of automotive applications. A first prototype of the flywheel system was tested experimentally and subsequently redesigned to improve rotordynamics and safety aspects. Coast-down experiments with the improved version show that the energy losses have been lowered significantly. The use of a kinetic energy storage device enables the uncoupling of vehicle wheel power and engine power. Therefore, the engine can be smaller and it can be chosen to operate in its region of best efficiency in start-stop mode. On a test-rig, the measured engine fuel consumption was reduced with more than 30 percent when the engine is intermittently restarted with the aid of the flywheel system. Although the start-stop mode proves to be advantageous for fuel consumption, exhaust gas emissions increase temporarily

  9. Optimisation of antimicrobial dosing based on pharmacokinetic and pharmacodynamic principles

    Directory of Open Access Journals (Sweden)

    Grace Si Ru Hoo

    2017-01-01

    Full Text Available While suboptimal dosing of antimicrobials has been attributed to poorer clinical outcomes, clinical cure and mortality advantages have been demonstrated when target pharmacokinetic (PK and pharmacodynamic (PD indices for various classes of antimicrobials were achieved to maximise antibiotic activity. Dosing optimisation requires a good knowledge of PK/PD principles. This review serves to provide a foundation in PK/PD principles for the commonly prescribed antibiotics (β-lactams, vancomycin, fluoroquinolones and aminoglycosides, as well as dosing considerations in special populations (critically ill and obese patients. PK principles determine whether an appropriate dose of antimicrobial reaches the intended pathogen(s. It involves the fundamental processes of absorption, distribution, metabolism and elimination, and is affected by the antimicrobial's physicochemical properties. Antimicrobial pharmacodynamics define the relationship between the drug concentration and its observed effect on the pathogen. The major indicator of the effect of the antibiotics is the minimum inhibitory concentration. The quantitative relationship between a PK and microbiological parameter is known as a PK/PD index, which describes the relationship between dose administered and the rate and extent of bacterial killing. Improvements in clinical outcomes have been observed when antimicrobial agents are dosed optimally to achieve their respective PK/PD targets. With the rising rates of antimicrobial resistance and a limited drug development pipeline, PK/PD concepts can foster more rational and individualised dosing regimens, improving outcomes while simultaneously limiting the toxicity of antimicrobials.

  10. Structural and operational optimisation of distributed energy systems

    International Nuclear Information System (INIS)

    Soederman, Jarmo; Pettersson, Frank

    2006-01-01

    A distributed energy system (DES) is a system comprising a set of energy suppliers and consumers, district heating pipelines, heat storage facilities and power transmission lines in a region. Distributed energy production has got an increasingly important role in the energy market. In this paper, a model for structural and operational optimisation of DES is presented. In the model, production and consumption of electrical power and heat, power transmissions, transport of fuels to the production plants, transport of water in the district heating pipelines and storage of heat are taken into account. The problem is formulated as a mixed integer linear programming (MILP) problem where the objective is to minimise the overall cost of DES, i.e., the sum of the running costs for the included operations and the annualised investment costs of the included equipment. An illustrative example is presented for a complex DES situation. The solution gives the DES structure, i.e., which production units, heat transport lines and storages should be built as well as their locations be, together with design parameters for plants and pipelines. The model enables the involved parties-suppliers, consumers, designers and authorities-to form a joint view of different situations as a basis for the decision making. A tool based on the model is built, which can be used in design, in creating guidelines for regional energy policies and for versatile what-if analyses

  11. Profile control studies for JET optimised shear regime

    Energy Technology Data Exchange (ETDEWEB)

    Litaudon, X.; Becoulet, A.; Eriksson, L.G.; Fuchs, V.; Huysmans, G.; How, J.; Moreau, D.; Rochard, F.; Tresset, G.; Zwingmann, W. [Association Euratom-CEA, CEA/Cadarache, Dept. de Recherches sur la Fusion Controlee, DRFC, 13 - Saint-Paul-lez-Durance (France); Bayetti, P.; Joffrin, E.; Maget, P.; Mayorat, M.L.; Mazon, D.; Sarazin, Y. [JET Abingdon, Oxfordshire (United Kingdom); Voitsekhovitch, I. [Universite de Provence, LPIIM, Aix-Marseille 1, 13 (France)

    2000-03-01

    This report summarises the profile control studies, i.e. preparation and analysis of JET Optimised Shear plasmas, carried out during the year 1999 within the framework of the Task-Agreement (RF/CEA/02) between JET and the Association Euratom-CEA/Cadarache. We report on our participation in the preparation of the JET Optimised Shear experiments together with their comprehensive analyses and the modelling. Emphasis is put on the various aspects of pressure profile control (core and edge pressure) together with detailed studies of current profile control by non-inductive means, in the prospects of achieving steady, high performance, Optimised Shear plasmas. (authors)

  12. Discontinuous permeable adsorptive barrier design and cost analysis: a methodological approach to optimisation.

    Science.gov (United States)

    Santonastaso, Giovanni Francesco; Bortone, Immacolata; Chianese, Simeone; Di Nardo, Armando; Di Natale, Michele; Erto, Alessandro; Karatza, Despina; Musmarra, Dino

    2017-09-19

    The following paper presents a method to optimise a discontinuous permeable adsorptive barrier (PAB-D). This method is based on the comparison of different PAB-D configurations obtained by changing some of the main PAB-D design parameters. In particular, the well diameters, the distance between two consecutive passive wells and the distance between two consecutive well lines were varied, and a cost analysis for each configuration was carried out in order to define the best performing and most cost-effective PAB-D configuration. As a case study, a benzene-contaminated aquifer located in an urban area in the north of Naples (Italy) was considered. The PAB-D configuration with a well diameter of 0.8 m resulted the best optimised layout in terms of performance and cost-effectiveness. Moreover, in order to identify the best configuration for the remediation of the aquifer studied, a comparison with a continuous permeable adsorptive barrier (PAB-C) was added. In particular, this showed a 40% reduction of the total remediation costs by using the optimised PAB-D.

  13. Optimisation of phase ratio in the triple jump using computer simulation.

    Science.gov (United States)

    Allen, Sam J; King, Mark A; Yeadon, M R Fred

    2016-04-01

    The triple jump is an athletic event comprising three phases in which the optimal proportion of each phase to the total distance jumped, termed the phase ratio, is unknown. This study used a whole-body torque-driven computer simulation model of all three phases of the triple jump to investigate optimal technique. The technique of the simulation model was optimised by varying torque generator activation parameters using a Genetic Algorithm in order to maximise total jump distance, resulting in a hop-dominated technique (35.7%:30.8%:33.6%) and a distance of 14.05m. Optimisations were then run with penalties forcing the model to adopt hop and jump phases of 33%, 34%, 35%, 36%, and 37% of the optimised distance, resulting in total distances of: 13.79m, 13.87m, 13.95m, 14.05m, and 14.02m; and 14.01m, 14.02m, 13.97m, 13.84m, and 13.67m respectively. These results indicate that in this subject-specific case there is a plateau in optimum technique encompassing balanced and hop-dominated techniques, but that a jump-dominated technique is associated with a decrease in performance. Hop-dominated techniques are associated with higher forces than jump-dominated techniques; therefore optimal phase ratio may be related to a combination of strength and approach velocity. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Intelligent Internet-based information system optimises diabetes mellitus management in communities.

    Science.gov (United States)

    Wei, Xuejuan; Wu, Hao; Cui, Shuqi; Ge, Caiying; Wang, Li; Jia, Hongyan; Liang, Wannian

    2018-05-01

    To evaluate the effect of an intelligent Internet-based information system upon optimising the management of patients diagnosed with type 2 diabetes mellitus (T2DM). In 2015, a T2DM information system was introduced to optimise the management of T2DM patients for 1 year in Fangzhuang community of Beijing, China. A total of 602 T2DM patients who were registered in the health service centre of Fangzhuang community were enrolled based on an isometric sampling technique. The data from 587 patients were used in the final analysis. The intervention effect was subsequently assessed by statistically comparing multiple parameters, such as the prevalence of glycaemic control, standard health management and annual outpatient consultation visits per person, before and after the implementation of the T2DM information system. In 2015, a total of 1668 T2DM patients were newly registered in Fangzhuang community. The glycaemic control rate was calculated as 37.65% in 2014 and significantly elevated up to 62.35% in 2015 ( p information system, the rate of standard health management was increased from 48.04% to 85.01% ( p information system optimised the management of T2DM patients in Fangzhuang community and decreased the outpatient numbers in both community and general hospitals, which played a positive role in assisting T2DM patients and their healthcare providers to better manage this chronic illness.

  15. Optimising radiation outcomes, scheduling patient waiting lists for maximum population tumour control

    International Nuclear Information System (INIS)

    Ebert, M.A.; Jennings, L.; Kearvell, R.; Bydder, S.

    2011-01-01

    Full text: Delays in the commencement of radiotherapy, possibly due to resource constraints, are known to impact on control-related outcomes. We sought an objective solution for patient prioritisation based on tumour control probability (TCP). With a utilitarian objective for maximising TCP in a population of M patients, with patient i waiting a time between diagnosis and treatment of Ti and a mean wait time of TMean, the optimisation problem is as shown. A linear-quadratic/Poissonian model for cell survival/TCP was considered including cell doubling during the wait time. Solutions to several distributions of patient population characteristics were examined together with the expected change in TCP for the population and individuals. An analytical solution to the optimisation problem was found which gives the optimal wait time for each patient as a function of the distribution of radiobiological characteristics in the population. This solution does not allow a negativity constraint on an individual's optimised waiting time so a waiting list simulation was developed to enforce that. Optimal wait time distributions were calculated for situations where patients are allocated distinct diagnostic groups (sharing radiobiological parameters) and for a (log-normal) distribution of doubling times in the population. In order to meet the utilitarian objective, the optimal solutions require patients with rapid cell doubling times to be accelerated up the waiting list at the expense of those with slowly proliferating tumours. The net population benefit however is comparable to or greater then the expected benefit from beam intensity modulation or dose escalation.

  16. Multi-objective optimisation of wastewater treatment plant control to reduce greenhouse gas emissions.

    Science.gov (United States)

    Sweetapple, Christine; Fu, Guangtao; Butler, David

    2014-05-15

    This study investigates the potential of control strategy optimisation for the reduction of operational greenhouse gas emissions from wastewater treatment in a cost-effective manner, and demonstrates that significant improvements can be realised. A multi-objective evolutionary algorithm, NSGA-II, is used to derive sets of Pareto optimal operational and control parameter values for an activated sludge wastewater treatment plant, with objectives including minimisation of greenhouse gas emissions, operational costs and effluent pollutant concentrations, subject to legislative compliance. Different problem formulations are explored, to identify the most effective approach to emissions reduction, and the sets of optimal solutions enable identification of trade-offs between conflicting objectives. It is found that multi-objective optimisation can facilitate a significant reduction in greenhouse gas emissions without the need for plant redesign or modification of the control strategy layout, but there are trade-offs to consider: most importantly, if operational costs are not to be increased, reduction of greenhouse gas emissions is likely to incur an increase in effluent ammonia and total nitrogen concentrations. Design of control strategies for a high effluent quality and low costs alone is likely to result in an inadvertent increase in greenhouse gas emissions, so it is of key importance that effects on emissions are considered in control strategy development and optimisation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Seasonal optimisation of panel surfaces in a photovoltaic plant; Optimisation saisonniere de la surface des panneaux dans une installation photovoltaique

    Energy Technology Data Exchange (ETDEWEB)

    Affolter, P.; Keller, L. [Bureau d`Etudes Keller-Burnier, Lavigny (CH)

    1991-02-01

    By carefully calculating the panel surface in a photovoltaic plant connected to the network, energy can be obtained at a minimum cost price. This has been discussed in a survey entitled `Optimisating the surface of photo= voltaic panels according to the static inverter`. This survey does not however describe how the price of energy varies during the year. This gap is filled by the present work which is helping show how to make optimum calculations in winter. Most of the simulations made during the course of the first study have been repeated. This has allowed new elements to be brought in. One example is the importance of the crystalline cell output-temperature characteristic. It is noted that the winter potential of a photovoltaic plant is greater than that of a solar power plant. This study has also facilitated better definition of the behaviour of the plant`s production-surface characteristic. This shows the importance of having a static inverter capable, in the event of intense periods of sunshine, of limiting the energy injected at rated power. Many parametric studies are helping to show the important parameters of this type of plant for the period from October to March. figs., 3 refs.

  18. Radiation induced late delayed alterations in mice brain after whole body and cranial radiation: a comparative DTI analysis

    International Nuclear Information System (INIS)

    Watve, Apurva; Gupta, Mamta; Trivedi, Richa; Khushu, Subash; Rana, Poonam

    2016-01-01

    Moderate dose of radiation exposure occurs during radiation accidents or radiation therapy induces pathophysiological alterations in CNS that may persist for longer duration. Studies suggest that late delayed injury is irreversible leading to metabolic and cognitive impairment. Our earlier studies have illustrated the varied response of brain at acute and early delayed phase on exposure to cranial and whole body radiation. Hence in continuation with our previous studies, present study focuses on comparative microstructural changes in brain at late delayed phase of radiation injury using Diffusion Tensor Imaging (DTI) technique. Region of interest (ROIs) were drawn on corpus callosum (CC), hippocampus (HIP), sensory-motor cortex (SMC), thalamus (TH), hypothalamus (HTH), cingulum (CG), caudeto-putamen (CUP) and cerebral peduncle (CP). The differences in FA (Fractional Anisotropy) and MD (Mean Diffusivity) values generated from these regions of all the groups were evaluated by ANOVA with multiple comparisons using Bonferroni, Post Hoc test. Maximum changes have been observed in MD values mainly in cranial group showing significantly increased MD in CC and SMC region while both the groups showed changes in TH and CUP region as compared to control. FA showed more prominent changes in whole body radiation group than cranial group by decreasing significantly in CP region while in HTH and CUP region in both the groups. Reduced FA indicates compromised structural integrity due to the loss of glial progenitor cells causing transient demyelination while increased MD has been equated with cellular membrane disruption, cell death and vasogenic edema. Thus, present study reveals late delayed CNS response after cranial and whole body radiation exposure. These findings can help us differentiate and monitor the pathophysiological changes at later stages either due to accidental or intentional exposure to ionizing radiation

  19. Ensuring effective and efficient forward gas markets: a report to the DTI [Department of Trade and Industry

    International Nuclear Information System (INIS)

    2005-01-01

    This Report was commissioned by the DTI to: review the workings of the UK forward market for gas; analyse forward prices seen over recent months; identify any material imperfections in the forward market; assess how the situation is likely to develop as a matter of course; and to bring forward recommendations capable of being implemented in the near-term as to how any such imperfections could be addressed. The task was approached from two directions: First, we brought to bear a wide range of technical methods, theoretical considerations and yardsticks that have been developed over many years of study of competitive commodity markets and forward markets worldwide. Using the analytic tools appropriate to the task, we processed the extensive data available on the UK gas market from the last decade to form a range of technical conclusions on the dynamics of the market. In parallel with this quantitative exercise, we interviewed 30 different market participants of widely varying profiles and market roles. The report is in two parts: Part A, in which we describe forward markets and their characteristics in general; analyse the workings of the UK gas forward market and identify issues that arise from the events of the past 12 months; and consider in detail whether market distortions are present as a consequence of the actions of any of the categories of market participants, or the structure of the gas market itself. We then consider forward price formation: first, in respect of whether forward prices for forthcoming winters can be justified as reflecting buyers' rational valuations for hedges; and second, in respect of the extreme events of October 2004 which have thus far lacked a compelling explanation. Part B, in which we consider the drivers of forward market prices, the outlook for their evolution in the medium term and the consequences of this for the market; and then make recommendations to improve the efficiency of the forward market in the near-term and end

  20. Protection against natural radiation: Optimisation and decision exercises

    International Nuclear Information System (INIS)

    O'Riordan, M.C.

    1984-02-01

    Six easy exercises are presented in which cost-benefit analysis is used to optimise protection against natural radiation or to decide whether protection is appropriate. The exercises are illustrative only and do not commit the Board. (author)

  1. Optimisation of wheat-sprouted soybean flour bread using response ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-11-16

    Nov 16, 2009 ... Full Length Research Paper. Optimisation of ... Victoria A. Jideani1* and Felix C. Onwubali2. 1Department of Food Technology, Cape Peninsula University of Technology, P. O. Box 652, Cape Town 8000, South. Africa.

  2. Optimised intake stroke analysis for flat and dome head pistons ...

    African Journals Online (AJOL)

    Optimised intake stroke analysis for flat and dome head pistons. ... in understanding the performance characteristics optioned between flat head and dome head pistons in engine design. ... EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

  3. Distributed optimisation problem with communication delay and external disturbance

    Science.gov (United States)

    Tran, Ngoc-Tu; Xiao, Jiang-Wen; Wang, Yan-Wu; Yang, Wu

    2017-12-01

    This paper investigates the distributed optimisation problem for the multi-agent systems (MASs) with the simultaneous presence of external disturbance and the communication delay. To solve this problem, a two-step design scheme is introduced. In the first step, based on the internal model principle, the internal model term is constructed to compensate the disturbance asymptotically. In the second step, a distributed optimisation algorithm is designed to solve the distributed optimisation problem based on the MASs with the simultaneous presence of disturbance and communication delay. Moreover, in the proposed algorithm, each agent interacts with its neighbours through the connected topology and the delay occurs during the information exchange. By utilising Lyapunov-Krasovskii functional, the delay-dependent conditions are derived for both slowly and fast time-varying delay, respectively, to ensure the convergence of the algorithm to the optimal solution of the optimisation problem. Several numerical simulation examples are provided to illustrate the effectiveness of the theoretical results.

  4. Shape optimisation and performance analysis of flapping wings

    KAUST Repository

    Ghommem, Mehdi; Collier, Nathan; Niemi, Antti; Calo, Victor M.

    2012-01-01

    optimised shapes produce efficient flapping flights, the wake pattern and its vorticity strength are examined. This work described in this paper should facilitate better guidance for shape design of engineered flying systems.

  5. Share-of-Surplus Product Line Optimisation with Price Levels

    Directory of Open Access Journals (Sweden)

    X. G. Luo

    2014-01-01

    Full Text Available Kraus and Yano (2003 established the share-of-surplus product line optimisation model and developed a heuristic procedure for this nonlinear mixed-integer optimisation model. In their model, price of a product is defined as a continuous decision variable. However, because product line optimisation is a planning process in the early stage of product development, pricing decisions usually are not very precise. In this research, a nonlinear integer programming share-of-surplus product line optimization model that allows the selection of candidate price levels for products is established. The model is further transformed into an equivalent linear mixed-integer optimisation model by applying linearisation techniques. Experimental results in different market scenarios show that the computation time of the transformed model is much less than that of the original model.

  6. Optimising a fall out dust monitoring sampling programme at a ...

    African Journals Online (AJOL)

    GREG

    Key words: Fall out dust monitoring, cement plant, optimising, air pollution sampling, fall out dust sampler locations. .... applied for those areas where controls are in place. Sampling ..... mass balance in the total cement manufacturing process.

  7. Issues with performance measures for dynamic multi-objective optimisation

    CSIR Research Space (South Africa)

    Helbig, M

    2013-06-01

    Full Text Available Symposium on Computational Intelligence in Dynamic and Uncertain Environments (CIDUE), Mexico, 20-23 June 2013 Issues with Performance Measures for Dynamic Multi-objective Optimisation Mard´e Helbig CSIR: Meraka Institute Brummeria, South Africa...

  8. Optimisation Study on the Production of Anaerobic Digestate ...

    African Journals Online (AJOL)

    DR. AMIN

    optimise the production of ADC from organic fractions of domestic wastes and the effects of ADC amendments on soil .... (22%), cooked meat (9%), lettuce (11%), carrots. (3%), potato (44%) ... seed was obtained from a mesophilic anaerobic.

  9. Optimising preterm nutrition: present and future

    LENUS (Irish Health Repository)

    Brennan, Ann-Marie

    2016-04-01

    The goal of preterm nutrition in achieving growth and body composition approximating that of the fetus of the same postmenstrual age is difficult to achieve. Current nutrition recommendations depend largely on expert opinion, due to lack of evidence, and are primarily birth weight based, with no consideration given to gestational age and\\/or need for catch-up growth. Assessment of growth is based predominately on anthropometry, which gives insufficient attention to the quality of growth. The present paper provides a review of the current literature on the nutritional management and assessment of growth in preterm infants. It explores several approaches that may be required to optimise nutrient intakes in preterm infants, such as personalising nutritional support, collection of nutrient intake data in real-time, and measurement of body composition. In clinical practice, the response to inappropriate nutrient intakes is delayed as the effects of under- or overnutrition are not immediate, and there is limited nutritional feedback at the cot-side. The accurate and non-invasive measurement of infant body composition, assessed by means of air displacement plethysmography, has been shown to be useful in assessing quality of growth. The development and implementation of personalised, responsive nutritional management of preterm infants, utilising real-time nutrient intake data collection, with ongoing nutritional assessments that include measurement of body composition is required to help meet the individual needs of preterm infants.

  10. Geometrical exploration of a flux-optimised sodium receiver through multi-objective optimisation

    Science.gov (United States)

    Asselineau, Charles-Alexis; Corsi, Clothilde; Coventry, Joe; Pye, John

    2017-06-01

    A stochastic multi-objective optimisation method is used to determine receiver geometries with maximum second law efficiency, minimal average temperature and minimal surface area. The method is able to identify a set of Pareto optimal candidates that show advantageous geometrical features, mainly in being able to maximise the intercepted flux within the geometrical boundaries set. Receivers with first law thermal efficiencies ranging from 87% to 91% are also evaluated using the second law of thermodynamics and found to have similar efficiencies of over 60%, highlighting the influence that the geometry can play in the maximisation of the work output of receivers by influencing the distribution of the flux from the concentrator.

  11. Intelligent Support for a Computer Aided Design Optimisation Cycle

    OpenAIRE

    B. Dolšak; M. Novak; J. Kaljun

    2006-01-01

    It is becoming more and more evident that  adding intelligence  to existing computer aids, such as computer aided design systems, can lead to significant improvements in the effective and reliable performance of various engineering tasks, including design optimisation. This paper presents three different intelligent modules to be applied within a computer aided design optimisation cycle to enable more intelligent and less experience-dependent design performance. 

  12. A supportive architecture for CFD-based design optimisation

    Science.gov (United States)

    Li, Ni; Su, Zeya; Bi, Zhuming; Tian, Chao; Ren, Zhiming; Gong, Guanghong

    2014-03-01

    Multi-disciplinary design optimisation (MDO) is one of critical methodologies to the implementation of enterprise systems (ES). MDO requiring the analysis of fluid dynamics raises a special challenge due to its extremely intensive computation. The rapid development of computational fluid dynamic (CFD) technique has caused a rise of its applications in various fields. Especially for the exterior designs of vehicles, CFD has become one of the three main design tools comparable to analytical approaches and wind tunnel experiments. CFD-based design optimisation is an effective way to achieve the desired performance under the given constraints. However, due to the complexity of CFD, integrating with CFD analysis in an intelligent optimisation algorithm is not straightforward. It is a challenge to solve a CFD-based design problem, which is usually with high dimensions, and multiple objectives and constraints. It is desirable to have an integrated architecture for CFD-based design optimisation. However, our review on existing works has found that very few researchers have studied on the assistive tools to facilitate CFD-based design optimisation. In the paper, a multi-layer architecture and a general procedure are proposed to integrate different CFD toolsets with intelligent optimisation algorithms, parallel computing technique and other techniques for efficient computation. In the proposed architecture, the integration is performed either at the code level or data level to fully utilise the capabilities of different assistive tools. Two intelligent algorithms are developed and embedded with parallel computing. These algorithms, together with the supportive architecture, lay a solid foundation for various applications of CFD-based design optimisation. To illustrate the effectiveness of the proposed architecture and algorithms, the case studies on aerodynamic shape design of a hypersonic cruising vehicle are provided, and the result has shown that the proposed architecture

  13. OPTIMISATION OF A DRIVE SYSTEM AND ITS EPICYCLIC GEAR SET

    OpenAIRE

    Bellegarde , Nicolas; Dessante , Philippe; Vidal , Pierre; Vannier , Jean-Claude

    2007-01-01

    International audience; This paper describes the design of a drive consisting of a DC motor, a speed reducer, a lead screw transformation system, a power converter and its associated DC source. The objective is to reduce the mass of the system. Indeed, the volume and weight optimisation of an electrical drive is an important issue for embedded applications. Here, we present an analytical model of the system in a specific application and afterwards an optimisation of the motor and speed reduce...

  14. Comparison of the diagnostic performances of diffusion parameters in diffusion weighted imaging and diffusion tensor imaging of breast lesions

    International Nuclear Information System (INIS)

    Cakir, Ozgur; Arslan, Arzu; Inan, Nagihan; Anık, Yonca; Sarısoy, Tahsin; Gumustas, Sevtap; Akansel, Gur

    2013-01-01

    Purpose: To evaluate the diagnostic efficiency of the diffusion parameters measured by conventional diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) for discrimination of malignant breast lesions from benign lesions and the normal breast. Materials and methods: The study included 52 women with 55 breast lesions (30 malignant, 25 benign). DTI and DWI were performed complementary to dynamic contrast MRI at 3T. Apparent diffusion coefficient (ADC) of DWI, mean diffusivity (MD) and fractional anisotropy (FA) values of DTI were measured for lesions and contralateral breast parenchyma in each patient. We used b factors of 0, 50, 850, 1000 and 1500 s/mm 2 for DWI and b 0 and 1000 s/mm 2 for DTI. ADC, MD and FA values were compared between malignant and benign lesions, and the normal parenchyma by univariate and multivariate analyses. Results: Diffusion parameters showed no difference according to menopausal status in the normal breast. ADC and MD values of the malignant lesions were significantly lower than benign lesions and normal parenchyma (p = 0.001). The FA showed no statistical significance. With the cut-off values of ≤1.23 × 10 −3 mm 2 /s (b 0–1000 s/mm 2 ) and ≤1.12 × 10 −3 mm 2 /s (b 0–1500 s/mm 2 ), ADC showed 92.85% and 96.15% sensitivity; 72.22% and 73.52% PPV, respectively. With a cut-off value of ≤1.27 × 10 −3 mm 2 /s (b 1000 s/mm 2 ), MD was 100% sensitive with a PPV of 65.90%. Comparing the diagnostic performance of the parameters in DTI with DWI, we obtained similar efficiency of ADC with b values of 0,1000 and 0,1500 s/mm 2 and MD with a b value of 0, 1000 s/mm 2 (AUC = 0.82 ± 0.07). Conclusion: ADC of DWI and MD of DTI values provide significant discriminative factors for benign and malignant breast lesions. FA measurement was not discriminative. Supported with clinical and dynamic contrast MRI findings, DWI and DTI findings provide significant contribution to the final radiologic decision

  15. Comparison of the diagnostic performances of diffusion parameters in diffusion weighted imaging and diffusion tensor imaging of breast lesions

    Energy Technology Data Exchange (ETDEWEB)

    Cakir, Ozgur, E-mail: cakirozgur@hotmail.com; Arslan, Arzu, E-mail: arzu.s.arslan@gmail.com; Inan, Nagihan, E-mail: nagihaninan@yahoo.com.tr; Anık, Yonca, E-mail: yoncaanik@yahoo.com; Sarısoy, Tahsin, E-mail: htsarisoy@yahoo.com; Gumustas, Sevtap, E-mail: svtgumustas@yahoo.com; Akansel, Gur, E-mail: gakansel@gmail.com

    2013-12-01

    Purpose: To evaluate the diagnostic efficiency of the diffusion parameters measured by conventional diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) for discrimination of malignant breast lesions from benign lesions and the normal breast. Materials and methods: The study included 52 women with 55 breast lesions (30 malignant, 25 benign). DTI and DWI were performed complementary to dynamic contrast MRI at 3T. Apparent diffusion coefficient (ADC) of DWI, mean diffusivity (MD) and fractional anisotropy (FA) values of DTI were measured for lesions and contralateral breast parenchyma in each patient. We used b factors of 0, 50, 850, 1000 and 1500 s/mm{sup 2} for DWI and b 0 and 1000 s/mm{sup 2} for DTI. ADC, MD and FA values were compared between malignant and benign lesions, and the normal parenchyma by univariate and multivariate analyses. Results: Diffusion parameters showed no difference according to menopausal status in the normal breast. ADC and MD values of the malignant lesions were significantly lower than benign lesions and normal parenchyma (p = 0.001). The FA showed no statistical significance. With the cut-off values of ≤1.23 × 10{sup −3} mm{sup 2}/s (b 0–1000 s/mm{sup 2}) and ≤1.12 × 10{sup −3} mm{sup 2}/s (b 0–1500 s/mm{sup 2}), ADC showed 92.85% and 96.15% sensitivity; 72.22% and 73.52% PPV, respectively. With a cut-off value of ≤1.27 × 10{sup −3} mm{sup 2}/s (b 1000 s/mm{sup 2}), MD was 100% sensitive with a PPV of 65.90%. Comparing the diagnostic performance of the parameters in DTI with DWI, we obtained similar efficiency of ADC with b values of 0,1000 and 0,1500 s/mm{sup 2} and MD with a b value of 0, 1000 s/mm{sup 2} (AUC = 0.82 ± 0.07). Conclusion: ADC of DWI and MD of DTI values provide significant discriminative factors for benign and malignant breast lesions. FA measurement was not discriminative. Supported with clinical and dynamic contrast MRI findings, DWI and DTI findings provide significant

  16. Production of gluconic acid using Micrococcus sp.: optimisation of carbon and nitrogen sources.

    Science.gov (United States)

    Joshi, V D; Sreekantiah, K R; Manjrekar, S P

    1996-01-01

    A process for production of gluconic acid from glucose by a Micrococcus sp. is described. More than 400 bacterial cultures isolated from local soil were tested for gluconic acid production. Three isolates, were selected on basis of their ability to produce gluconic acid and high titrable acidity. These were identified as Micrococcus sp. and were named M 27, M 54 and M 81. Nutritional and other parameters for maximum production of gluconic acid by the selected isolates were optimised. It was found that Micrococcus sp. isolate M 27 gave highest yield of 8.19 g gluconic acid from 9 g glucose utilised giving 91% conversion effeciency.

  17. A robust optimisation approach to the problem of supplier selection and allocation in outsourcing

    Science.gov (United States)

    Fu, Yelin; Keung Lai, Kin; Liang, Liang

    2016-03-01

    We formulate the supplier selection and allocation problem in outsourcing under an uncertain environment as a stochastic programming problem. Both the decision-maker's attitude towards risk and the penalty parameters for demand deviation are considered in the objective function. A service level agreement, upper bound for each selected supplier's allocation and the number of selected suppliers are considered as constraints. A novel robust optimisation approach is employed to solve this problem under different economic situations. Illustrative examples are presented with managerial implications highlighted to support decision-making.

  18. Optimisation of the formulation of a bubble bath by a chemometric approach market segmentation and optimisation.

    Science.gov (United States)

    Marengo, Emilio; Robotti, Elisa; Gennaro, Maria Carla; Bertetto, Mariella

    2003-03-01

    The optimisation of the formulation of a commercial bubble bath was performed by chemometric analysis of Panel Tests results. A first Panel Test was performed to choose the best essence, among four proposed to the consumers; the best essence chosen was used in the revised commercial bubble bath. Afterwards, the effect of changing the amount of four components (the amount of primary surfactant, the essence, the hydratant and the colouring agent) of the bubble bath was studied by a fractional factorial design. The segmentation of the bubble bath market was performed by a second Panel Test, in which the consumers were requested to evaluate the samples coming from the experimental design. The results were then treated by Principal Component Analysis. The market had two segments: people preferring a product with a rich formulation and people preferring a poor product. The final target, i.e. the optimisation of the formulation for each segment, was obtained by the calculation of regression models relating the subjective evaluations given by the Panel and the compositions of the samples. The regression models allowed to identify the best formulations for the two segments ofthe market.

  19. Methodological principles for optimising functional MRI experiments; Methodische Grundlagen der Optimierung funktioneller MR-Experimente

    Energy Technology Data Exchange (ETDEWEB)

    Wuestenberg, T. [Georg-August-Universitaet Goettingen, Abteilung fuer Medizinische Psychologie (Germany); Georg-August-Universitaet, Abteilung fuer Medizinische Psychologie, Goettingen (Germany); Giesel, F.L. [Deutsches Kebsforschungszentrum (DKFZ) Heidelberg, Abteilung fuer Radiologische Diagnostik (Germany); Strasburger, H. [Georg-August-Universitaet Goettingen, Abteilung fuer Medizinische Psychologie (Germany)

    2005-02-01

    Functional magnetic resonance imaging (fMRI) is one of the most common methods for localising neuronal activity in the brain. Even though the sensitivity of fMRI is comparatively low, the optimisation of certain experimental parameters allows obtaining reliable results. In this article, approaches for optimising the experimental design, imaging parameters and analytic strategies will be discussed. Clinical neuroscientists and interested physicians will receive practical rules of thumb for improving the efficiency of brain imaging experiments. (orig.) [German] Die funktionelle Magnetresonanztomographie (fMRT) des Zentralnervensystems ist eine der meistgenutzten Methoden zur Lokalisierung neuronaler Aktivitaet im Gehirn. Obwohl die Sensitivitaet der fMRT vergleichsweise gering ist, kann durch die Auswahl geeigneter experimenteller Parameter die Empfindlichkeit dieses bildgebenden Verfahrens gesteigert und die Reliabilitaet der Ergebnisse gewaehrleistet werden. In diesem Artikel werden deshalb Ansaetze fuer die Optimierung des Paradigmendesigns, der MR-Bildgebung und der Datenauswertung diskutiert. Klinischen Forschern und interessierten Aerzten sollen dadurch Richtgroessen fuer die Durchfuehrung effektiver fMRT-Experimente vermittelt werden. (orig.)

  20. Optimisation of a propagation-based x-ray phase-contrast micro-CT system

    Science.gov (United States)

    Nesterets, Yakov I.; Gureyev, Timur E.; Dimmock, Matthew R.

    2018-03-01

    Micro-CT scanners find applications in many areas ranging from biomedical research to material sciences. In order to provide spatial resolution on a micron scale, these scanners are usually equipped with micro-focus, low-power x-ray sources and hence require long scanning times to produce high resolution 3D images of the object with acceptable contrast-to-noise. Propagation-based phase-contrast tomography (PB-PCT) has the potential to significantly improve the contrast-to-noise ratio (CNR) or, alternatively, reduce the image acquisition time while preserving the CNR and the spatial resolution. We propose a general approach for the optimisation of the PB-PCT imaging system. When applied to an imaging system with fixed parameters of the source and detector this approach requires optimisation of only two independent geometrical parameters of the imaging system, i.e. the source-to-object distance R 1 and geometrical magnification M, in order to produce the best spatial resolution and CNR. If, in addition to R 1 and M, the system parameter space also includes the source size and the anode potential this approach allows one to find a unique configuration of the imaging system that produces the required spatial resolution and the best CNR.

  1. Tapped density optimisation for four agricultural wastes - Part II: Performance analysis and Taguchi-Pareto

    Directory of Open Access Journals (Sweden)

    Ajibade Oluwaseyi Ayodele

    2016-01-01

    Full Text Available In this attempt, which is a second part of discussions on tapped density optimisation for four agricultural wastes (particles of coconut, periwinkle, palm kernel and egg shells, performance analysis for comparative basis is made. This paper pioneers a study direction in which optimisation of process variables are pursued using Taguchi method integrated with the Pareto 80-20 rule. Negative percentage improvements resulted when the optimal tapped density was compared with the average tapped density. However, the performance analysis between optimal tapped density and the peak tapped density values yielded positive percentage improvements for the four filler particles. The performance analysis results validate the effectiveness of using the Taguchi method in improving the tapped density properties of the filler particles. The application of the Pareto 80-20 rule to the table of parameters and levels produced revised tables of parameters and levels which helped to identify the factor-levels position of each parameter that is economical to optimality. The Pareto 80-20 rule also produced revised S/N response tables which were used to know the relevant S/N ratios that are relevant to optimality.

  2. Optimisation of integrated energy and materials systems

    International Nuclear Information System (INIS)

    Gielen, D.J.; Okken, P.A.

    1994-06-01

    To define cost-effective long term CO2 reduction strategies an integrated energy and materials system model for the Netherlands for the period 2000-2040 is developed. The model is based upon the energy system model MARKAL, which configures an optimal mix of technologies to satisfy the specified energy and product/materials service demands. This study concentrates on CO 2 emission reduction in the materials system. For this purpose, the energy system model is enlarged with a materials system model including all steps 'from cradle to grave'. The materials system model includes 29 materials, 20 product groups and 30 waste materials. The system is divided into seven types of technologies; 250 technologies are modeled. The results show that the integrated optimisation of the energy system and the materials system can significantly reduce the emission reduction costs, especially at higher reduction percentages. The reduction is achieved through shifts in materials production and waste handling and through materials substitution in products. Shifts in materials production and waste management seem cost-effective, while the cost-effectiveness of shifts in product composition is sensitive due to the cost structure of products. For the building sector, transportation applications and packaging, CO 2 policies show a significant impact on prices, and shifts in product composition could occur. For other products, the reduction through materials substitution seems less promising. The impact on materials consumption seems most significant for cement (reduced), timber and aluminium (both increased). For steel and plastics, the net effect is balanced, but shifts between applications do occur. The MARKAL-approach is feasible to study integrated energy and materials systems. The progress compared to other environmental system analysis instruments is much more insight in the interaction of technologies on a national scale and in time

  3. Design and formulation of nano-sized spray dried efavirenz. Part I: Influence of formulation parameters

    CSIR Research Space (South Africa)

    Katata, L

    2012-10-01

    Full Text Available statistical design with an L8 orthogonal array, was implemented to optimise the formulation parameters of PCL-EFV nanoparticles. The types of sugar (lactose or trehalose), surfactant concentration and solvent (dichloromethane and ethyl acetate) were chosen...

  4. Optimising Reactive Control in non-ideal Efficiency Wave Energy Converters

    DEFF Research Database (Denmark)

    Strager, Thomas; Lopez, Pablo Fernandez; Giorgio, Giuseppe

    2014-01-01

    When analytically optimising the control strategy in wave energy converters which use a point absorber, the efficiency aspect is generally neglected. The results presented in this paper provide an analytical expression for the mean harvested electrical power in non-ideal efficiency situations....... These have been derived under the assumptions of monochromatic incoming waves and linear system behaviour. This allows to establish the power factor of a system with non-ideal efficiency. The locus of the optimal reactive control parameters is then studied and an alternative method of representation...... is developed to model the optimal control parameters. Ultimately we present a simple method of choosing optimal control parameters for any combination of efficiency and wave frequency....

  5. Progressive decline in fractional anisotropy on serial DTI examinations of the corpus callosum: a putative marker of disease activity and progression in SPMS

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Wei; Zhu, Tong; Zhong, Jianhui; Liu, Xiang [University of Rochester Medical Center, Department of Imaging Sciences, Rochester, NY (United States); Rao, Praveen; Segal, Benjamin M. [University of Michigan, Department of Neurology, Holtom-Garrett Program in Neuroimmunology, Ann Arbor, MI (United States); Ekholm, Sven [University of Rochester Medical Center, Department of Imaging Sciences, Rochester, NY (United States); University of Rochester Medical Center, Division of Diagnostic and Interventional Neuroradiology, Rochester, NY (United States)

    2012-04-15

    Clinical trials of secondary progressive multiple sclerosis (SPMS) is lacking reliable biomarkers or outcome measures that reflect tissue injury incurred within a 1- to 2-year observation period. Diffusion tensor imaging (DTI) is sensitive in detecting acute brain tissue damage. We monitored SPMS patients over 12 months for diffusion changes within the corpus callosum (CC). Bimonthly MRI examinations over a 1-year period were performed on 11 SPMS patients. The protocol included postcontrast T1-weighted images and DTI. Based on the appearance of T1 enhancing lesion(s) during the study period, the patients were divided into enhancing (five patients) and nonenhancing (six patients) groups. Fractional anisotropy (FA) and mean diffusivity (MD) of the genu, body, and splenium of the CC were measured and temporal changes in mean FA and MD were evaluated for each group as well as between groups. Immunology data from peripheral blood mononuclear cells were also collected on a monthly basis. The enhancing group showed significant, progressive decrease in FA in body (p = 0.012) and splenium (p = 0.033) of CC, and significantly higher lymphotoxin-{beta} levels. No significant FA changes were seen in the nonenhancing group. Moreover, the FA decline in the enhancing group deviated significantly from the nonenhancing group, which remained essentially stable. Although MD increased slightly in both groups, there was no significant difference between the two groups. Based on the MR and immunology findings, the results of our study suggest that DTI undergo more rapid and longitudinal changes in SPMS patients with inflammatory activity. (orig.)

  6. Combination of Resting state fMRI, DTI and sMRI Data to Discriminate Schizophrenia by N-way MCCA+jICA

    Directory of Open Access Journals (Sweden)

    Jing eSui

    2013-05-01

    Full Text Available Multimodal brain imaging data have shown increasing utility in answering both scientifically interesting and clinically relevant questions. Each brain imaging technique provides a different view of brain function or structure, while multimodal fusion capitalizes on the strength of each and may uncover hidden relationships that can merge findings from separate neuroimaging studies. However, most current approaches have focused on pair-wise fusion and there is still relatively little work on N-way data fusion and examination of the relationships among multiple data types. We recently developed an approach called mCCA+jICA" as a novel multi-way fusion method which is able to investigate the disease risk factors that are either shared or distinct across multiple modalities as well as the full correspondence across modalities. In this paper, we applied this model to combine resting state fMRI (amplitude of low-frequency fluctuation, ALFF, grey matter density (GM and DTI (fractional anisotropy, FA data, in order to elucidate the abnormalities underlying schizophrenia patients (SZs, n=35 relative to healthy controls (HCs, n=28. Both modality-common and modality-unique abnormal regions were identified in SZs, which were then used for successful classification for 7 modality-combinations, showing the potential for a broad applicability of the mCCA+jICA model and its results. In addition, a pair of GM-DTI components showed significant correlation with the positive symptom subscale of Positive and Negative Syndrome Scale (PANSS, suggesting that gray matter density changes in default model network along with white matter disruption in anterior thalamic radiation are associated with increased positive PANSS. Findings suggest the DTI anisotropy changes in frontal lobe may relate to the corresponding functional/structural changes in prefrontal cortex and superior temporal gyrus that are thought to play a role in the clinical expression of schizophrenia.

  7. MRI assessment of the thigh musculature in dermatomyositis and healthy subjects using diffusion tensor imaging, intravoxel incoherent motion and dynamic DTI.

    Science.gov (United States)

    Sigmund, E E; Baete, S H; Luo, T; Patel, K; Wang, D; Rossi, I; Duarte, A; Bruno, M; Mossa, D; Femia, A; Ramachandran, S; Stoffel, D; Babb, J S; Franks, A; Bencardino, J

    2018-06-04

    Dermatomyositis (DM) is an idiopathic inflammatory myopathy involving severe debilitation in need of diagnostics. We evaluated the proximal lower extremity musculature with diffusion tensor imaging (DTI), intravoxel incoherent motion (IVIM) and dynamic DTI in DM patients and controls and compared with standard clinical workup.  METHODS: In this IRB-approved, HIPAA-compliant study with written informed consent, anatomical, Dixon fat/water and diffusion imaging were collected in bilateral thigh MRI of 22 controls and 27 DM patients in a 3T scanner. Compartments were scored on T1/T2 scales. Single voxel dynamic DTI metrics in quadriceps before and after 3-min leg exercise were measured. Spearman rank correlation and mixed model analysis of variance/covariance (ANOVA/ANCOVA) were used to correlate with T1 and T2 scores and to compare patients with controls. DM patients showed significantly lower pseudo-diffusion and volume in quadriceps than controls. All subjects showed significant correlation between T1 score and signal-weighted fat fraction; tissue diffusion and pseudo-diffusion varied significantly with T1 and T2 score in patients. Radial and mean diffusion exercise response in patients was significantly higher than controls. Static and dynamic diffusion imaging metrics show correlation with conventional imaging scores, reveal spatial heterogeneity, and provide means to differentiate dermatomyositis patients from controls. • Diffusion imaging shows regional differences between thigh muscles of dermatomyositis patients and controls. • Signal-weighted fat fraction and diffusion metrics correlate with T1/T2 scores of disease severity. • Dermatomyositis patients show significantly higher radial diffusion exercise response than controls.

  8. Neonatal brain microstructure correlates of neurodevelopment and gait in preterm children 18-22 mo of age: an MRI and DTI study.

    Science.gov (United States)

    Rose, Jessica; Cahill-Rowley, Katelyn; Vassar, Rachel; Yeom, Kristen W; Stecher, Ximena; Stevenson, David K; Hintz, Susan R; Barnea-Goraly, Naama

    2015-12-01

    Near-term brain structure was examined in preterm infants in relation to neurodevelopment. We hypothesized that near-term macrostructural brain abnormalities identified using conventional magnetic resonance imaging (MRI), and white matter (WM) microstructure detected using diffusion tensor imaging (DTI), would correlate with lower cognitive and motor development and slower, less-stable gait at 18-22 mo of age. One hundred and two very-low-birth-weight preterm infants (≤1,500 g birth weight; ≤32 wk gestational age) were recruited prior to routine near-term brain MRI at 36.6 ± 1.8 wk postmenstrual age. Cerebellar and WM macrostructure was assessed on conventional structural MRI. DTI was obtained in 66 out of 102 and WM microstructure was assessed using fractional anisotropy and mean diffusivity (MD) in six subcortical brain regions defined by DiffeoMap neonatal atlas. Neurodevelopment was assessed with Bayley-Scales-of-Infant-Toddler-Development, 3rd-Edition (BSID-III); gait was assessed using an instrumented mat. Neonates with cerebellar abnormalities identified using MRI demonstrated lower mean BSID-III cognitive composite scores (89.0 ± 10.1 vs. 97.8 ± 12.4; P = 0.002) at 18-22 mo. Neonates with higher DTI-derived left posterior limb of internal capsule (PLIC) MD demonstrated lower cognitive and motor composite scores (r = -0.368; P = 0.004; r = -0.354; P = 0.006) at 18-22 mo; neonates with higher genu MD demonstrated slower gait velocity (r = -0.374; P = 0.007). Multivariate linear regression significantly predicted cognitive (adjusted r(2) = 0.247; P = 0.002) and motor score (adjusted r(2) = 0.131; P = 0.017). Near-term cerebellar macrostructure and PLIC and genu microstructure were predictive of early neurodevelopment and gait.

  9. Numerical analysis and optimisation of heavy water upgrading column

    International Nuclear Information System (INIS)

    Sankar, Rama; Ghosh, Brindaban; Bhanja, K.

    2013-01-01

    In the 'Pressurised Heavy Water' type of reactors, heavy water is used both as moderator and coolant. During operation of reactor downgraded heavy water is generated that needs to be upgraded for reuse in the reactor. When the isotopic purity of heavy water becomes less than 99.75%, it is termed as downgraded heavy water. Downgraded heavy water also contains impurity such as corrosion products, dirt, oil etc. Upgradation of downgraded heavy water is normally done in two steps: (i) Purification: In this step downgraded heavy water is first purified to remove corrosion products, dirt, oil, etc. and (ii) Upgradation of heavy water to increase its isotopic purity, this step is carried out by vacuum distillation of downgraded heavy water after purification. This project is aimed at mathematical modelling and numerical simulation of heavy water upgrading column. Modelling and simulation studies of the upgradation column are based on equilibrium stage model to evaluate the effect of feed location, pressure, feed composition, reflux ratio in the packed column for given reboiler and condenser duty of distillation column. State to stage modelling of two-phase two-component flow has constitutes the overall modelling of the column. The governing equations consist of stage-wise species and overall mass continuity and stage-wise energy balance. This results in tridigonal matrix equation for stage liquid fractions for heavy and light water. The stage-wise liquid flow rates and temperatures are governed by stage-wise mass and energy balance. The combined form of the corresponding governing equations, with the incorporation of thermodynamic equation of states, form a system of nonlinear equations. This system have been resolved numerically using modified Newton-Raphson method. A code in the MATLAB platform has been developed by on above numerical procedure. The optimisation of the column operating conditions is to be carried out based on parametric studies and analysis of different

  10. Translating state-of-the-art spinal cord MRI techniques to clinical use: A systematic review of clinical studies utilizing DTI, MT, MWF, MRS, and fMRI

    Directory of Open Access Journals (Sweden)

    Allan R. Martin

    2016-01-01

    Conclusions: State-of-the-art spinal cord MRI techniques are emerging with great potential to improve the diagnosis and management of various spinal pathologies, but the current body of evidence has only showed limited clinical utility to date. Among these imaging tools DTI is the most mature, but further work is necessary to standardize and validate its use before it will be adopted in the clinical realm. Large, well-designed studies with a priori hypotheses, standardized acquisition methods, detailed clinical data collection, and robust automated analysis techniques are needed to fully demonstrate the potential of these rapidly evolving techniques.

  11. Evaluation of glymphatic system activity with the diffusion MR technique: diffusion tensor image analysis along the perivascular space (DTI-ALPS) in Alzheimer’s disease cases

    OpenAIRE

    Taoka, Toshiaki; Masutani, Yoshitaka; Kawai, Hisashi; Nakane, Toshiki; Matsuoka, Kiwamu; Yasuno, Fumihiko; Kishimoto, Toshifumi; Naganawa, Shinji

    2017-01-01

    Purpose: The activity of the glymphatic system is impaired in animal models of Alzheimer’s disease (AD). We evaluated the activity of the human glymphatic system in cases of AD with a diffusion-based technique called diffusion tensor image analysis along the perivascular space (DTI-ALPS). Materials and methods: Diffusion tensor images were acquired to calculate diffusivities in the x, y, and z axes of the plane of the lateral ventricle body in 31 patients. We evaluated the diffusivity along t...

  12. Transmit Power Optimisation in Wireless Network

    Directory of Open Access Journals (Sweden)

    Besnik Terziu

    2011-09-01

    Full Text Available Transmit power optimisation in wireless networks based on beamforming have emerged as a promising technique to enhance the spectrum efficiency of present and future wireless communication systems. The aim of this study is to minimise the access point power consumption in cellular networks while maintaining a targeted quality of service (QoS for the mobile terminals. In this study, the targeted quality of service is delivered to a mobile station by providing a desired level of Signal to Interference and Noise Ratio (SINR. Base-stations are coordinated across multiple cells in a multi-antenna beamforming system. This study focuses on a multi-cell multi-antenna downlink scenario where each mobile user is equipped with a single antenna, but where multiple mobile users may be active simultaneously in each cell and are separated via spatial multiplexing using beamforming. The design criteria is to minimize the total weighted transmitted power across the base-stations subject to SINR constraints at the mobile users. The main contribution of this study is to define an iterative algorithm that is capable of finding the joint optimal beamformers for all basestations, based on a correlation-based channel model, the full-correlation model. Among all correlated channel models, the correlated channel model used in this study is the most accurate, giving the best performance in terms of power consumption. The environment here in this study is chosen to be Non-Light of- Sight (NLOS condition, where a signal from a wireless transmitter passes several obstructions before arriving at a wireless receiver. Moreover there are many scatterers local to the mobile, and multiple reflections can occur among them before energy arrives at the mobile. The proposed algorithm is based on uplink-downlink duality using the Lagrangian duality theory. Time-Division Duplex (TDD is chosen as the platform for this study since it has been adopted to the latest technologies in Fourth

  13. Establishing Local Reference Dose Values and Optimisation Strategies

    International Nuclear Information System (INIS)

    Connolly, P.; Moores, B.M.

    2000-01-01

    The revised EC Patient Directive 97/43 EURATOM introduces the concepts of clinical audit, diagnostic reference levels and optimisation of radiation protection in diagnostic radiology. The application of reference dose levels in practice involves the establishment of reference dose values as actual measurable operational quantities. These values should then form part of an ongoing optimisation and audit programme against which routine performance can be compared. The CEC Quality Criteria for Radiographic Images provides guidance reference dose values against which local performance can be compared. In many cases these values can be improved upon quite considerably. This paper presents the results of a local initiative in the North West of the UK aimed at establishing local reference dose values for a number of major hospital sites. The purpose of this initiative is to establish a foundation for both optimisation strategies and clinical audit as an ongoing and routine practice. The paper presents results from an ongoing trial involving patient dose measurements for several radiological examinations upon the sites. The results of an attempt to establish local reference dose values from measured dose values and to employ them in optimisation strategies are presented. In particular emphasis is placed on the routine quality control programmes necessary to underpin this strategy including the effective data management of results from such programmes and how they can be employed to optimisation practices. (author)

  14. Image quality and dose optimisation for infant CT using a paediatric phantom

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, Jack W.; Phelps, Andrew S.; Courtier, Jesse L.; Gould, Robert G.; MacKenzie, John D. [University of California, San Francisco, Department of Radiology and Biomedical Imaging, San Francisco, CA (United States)

    2016-05-15

    To optimise image quality and reduce radiation exposure for infant body CT imaging. An image quality CT phantom was created to model the infant body habitus. Image noise, spatial resolution, low contrast detectability and tube current modulation (TCM) were measured after adjusting CT protocol parameters. Reconstruction method (FBP, hybrid iterative and model-based iterative), image quality reference parameter, helical pitch and beam collimation were systematically investigated for their influence on image quality and radiation output. Both spatial and low contrast resolution were significantly improved with model-based iterative reconstruction (p < 0.05). A change in the helical pitch from 0.969 to 1.375 resulted in a 23 % reduction in total TCM, while a change in collimation from 20 to 40 mm resulted in a 46 % TCM reduction. Image noise and radiation output were both unaffected by changes in collimation, while an increase in pitch enabled a dose length product reduction of ∝6 % at equivalent noise. An optimised protocol with ∝30 % dose reduction was identified using model-based iterative reconstruction. CT technology continues to evolve and require protocol redesign. This work provides an example of how an infant-specific phantom is essential for leveraging this technology to maintain image quality while reducing radiation exposure. (orig.)

  15. Data for TROTS – The Radiotherapy Optimisation Test Set

    Directory of Open Access Journals (Sweden)

    Sebastiaan Breedveld

    2017-06-01

    Full Text Available The Radiotherapy Optimisation Test Set (TROTS is an extensive set of problems originating from radiotherapy (radiation therapy treatment planning. This dataset is created for 2 purposes: (1 to supply a large-scale dense dataset to measure performance and quality of mathematical solvers, and (2 to supply a dataset to investigate the multi-criteria optimisation and decision-making nature of the radiotherapy problem. The dataset contains 120 problems (patients, divided over 6 different treatment protocols/tumour types. Each problem contains numerical data, a configuration for the optimisation problem, and data required to visualise and interpret the results. The data is stored as HDF5 compatible Matlab files, and includes scripts to work with the dataset.

  16. CLIC crab cavity design optimisation for maximum luminosity

    Energy Technology Data Exchange (ETDEWEB)

    Dexter, A.C., E-mail: a.dexter@lancaster.ac.uk [Lancaster University, Lancaster, LA1 4YR (United Kingdom); Cockcroft Institute, Daresbury, Warrington, WA4 4AD (United Kingdom); Burt, G.; Ambattu, P.K. [Lancaster University, Lancaster, LA1 4YR (United Kingdom); Cockcroft Institute, Daresbury, Warrington, WA4 4AD (United Kingdom); Dolgashev, V. [SLAC, Menlo Park, CA 94025 (United States); Jones, R. [University of Manchester, Manchester, M13 9PL (United Kingdom)

    2011-11-21

    The bunch size and crossing angle planned for CERN's compact linear collider CLIC dictate that crab cavities on opposing linacs will be needed to rotate bunches of particles into alignment at the interaction point if the desired luminosity is to be achieved. Wakefield effects, RF phase errors between crab cavities on opposing linacs and unpredictable beam loading can each act to reduce luminosity below that anticipated for bunches colliding in perfect alignment. Unlike acceleration cavities, which are normally optimised for gradient, crab cavities must be optimised primarily for luminosity. Accepting the crab cavity technology choice of a 12 GHz, normal conducting, travelling wave structure as explained in the text, this paper develops an analytical approach to optimise cell number and iris diameter.

  17. Cultural-based particle swarm for dynamic optimisation problems

    Science.gov (United States)

    Daneshyari, Moayed; Yen, Gary G.

    2012-07-01

    Many practical optimisation problems are with the existence of uncertainties, among which a significant number belong to the dynamic optimisation problem (DOP) category in which the fitness function changes through time. In this study, we propose the cultural-based particle swarm optimisation (PSO) to solve DOP problems. A cultural framework is adopted incorporating the required information from the PSO into five sections of the belief space, namely situational, temporal, domain, normative and spatial knowledge. The stored information will be adopted to detect the changes in the environment and assists response to the change through a diversity-based repulsion among particles and migration among swarms in the population space, and also helps in selecting the leading particles in three different levels, personal, swarm and global levels. Comparison of the proposed heuristics over several difficult dynamic benchmark problems demonstrates the better or equal performance with respect to most of other selected state-of-the-art dynamic PSO heuristics.

  18. Patient and staff dose optimisation in nuclear medicine diagnosis methods

    International Nuclear Information System (INIS)

    Marta Wasilewska-Radwanska; Katarzyna Natkaniec

    2007-01-01

    Complete test of publication follows. The implementation of the Basic Safety Standards (BSS) Directive 96/29 on the protection of workers and general population against the danger arising from ionising radiation and the Directive 97/43 on health protection of individuals against dangers of ionising radiation in relation to medical exposure, known as the Medical Exposure Directive (MED), they started in Poland some years ago with the Polish Atomic Law and executive orders published by the Polish Government and Polish Health Minister. Poland's Government has applied for several years transitory period to complete implementation of the Directive 97/43/Euratom because of the technical, organising and economical problems related with this procedure. The most important task has arisen to prepare procedures according with the current state of knowledge in the area of Quality Assurance (QA) and Quality Control (QC) of medical equipment using ionising radiation in diagnosis. QA and QC in X-ray diagnosis equipment started to be introduced since several years ago and nowadays they are put in common practice in almost each X-ray laboratory in Poland. As result, the nuclear medicine departments must follows the new legislation which has imposed also obligatory necessity of regular Quality Assurance and Quality Control of equipment and procedures for preparing and using radiopharmaceuticals. Documentation for QA system in nuclear medicine includes, among others, quality book, general procedures applied in diagnosis, description of specific procedures prepared in accordance with the rules in current legislation. The physical parameters of equipment (gamma camera, SPECT) undergo the basic tests and some special ones. The basic tests are carried out by staff of the nuclear medicine department. Units with accreditation perform special tests annually. The basic test for planar gamma camera includes: measurement of radioactivity, measurement of background, estimation of photons energy

  19. The principle of optimisation: reasons for success and legal criticism

    International Nuclear Information System (INIS)

    Fernandez Regalado, Luis

    2008-01-01

    The International Commission on Radiological Protection (ICRP) has adopted new recommendations in 2007. In broad outlines they fundamentally continue the recommendations already approved in 1990 and later on. The principle of optimisation of protection, together with the principles of justification and dose limits, remains playing a key role of the ICRP recommendations, and it has so been for the last few years. This principle, somehow reinforced in the 2007 ICRP recommendations, has been incorporated into norms and legislation which have peacefully been in force in many countries all over the world. There are three main reasons to explain the success in the application of the principle of optimisation in radiological protection: First, the subjectivity of the sentence that embraces the principle of optimisation, 'As low as reasonably achievable' (ALARA), that allows different valid interpretations under different circumstances. Second, the pragmatism and adaptability of ALARA to all exposure situations. And third, the scientific humbleness which is behind the principle of optimisation, which makes a clear contrast with the old fashioned scientific positivism that enshrined scientist opinions. Nevertheless, from a legal point of view, there is some criticism cast over the principle of optimisation in radiological protection, where it has been transformed in compulsory norm. This criticism is based on two arguments: The lack of democratic participation in the process of elaboration of the norm, and the legal uncertainty associated to its application. Both arguments are somehow known by the ICRP which, on the one hand, has broadened the participation of experts, associations and the professional radiological protection community, increasing the transparency on how decisions on recommendations have been taken, and on the other hand, the ICRP has warned about the need for authorities to specify general criteria to develop the principle of optimisation in national

  20. Optimisation in X-ray and Molecular Imaging 2015

    International Nuclear Information System (INIS)

    Baath, Magnus; Hoeschen, Christoph; Mattsson, Soeren; Mansson, Lars Gunnar

    2016-01-01

    This issue of Radiation Protection Dosimetry is based on contributions to Optimisation in X-ray and Molecular Imaging 2015 - the 4. Malmoe Conference on Medical Imaging (OXMI 2015). The conference was jointly organised by members of former and current research projects supported by the European Commission EURATOM Radiation Protection Research Programme, in cooperation with the Swedish Society for Radiation Physics. The conference brought together over 150 researchers and other professionals from hospitals, universities and industries with interests in different aspects of the optimisation of medical imaging. More than 100 presentations were given at this international gathering of medical physicists, radiologists, engineers, technicians, nurses and educational researchers. Additionally, invited talks were offered by world-renowned experts on radiation protection, spectral imaging and medical image perception, thus covering several important aspects of the generation and interpretation of medical images. The conference consisted of 13 oral sessions and a poster session, as reflected by the conference title connected by their focus on the optimisation of the use ionising radiation in medical imaging. The conference included technology-specific topics such as computed tomography and tomosynthesis, but also generic issues of interest for the optimisation of all medical imaging, such as image perception and quality assurance. Radiation protection was covered by e.g. sessions on patient dose benchmarking and occupational exposure. Technically-advanced topics such as modelling, Monte Carlo simulation, reconstruction, classification, and segmentation were seen taking advantage of recent developments of hardware and software, showing that the optimisation community is at the forefront of technology and adapts well to new requirements. These peer-reviewed proceedings, representing a continuation of a series of selected reports from meetings in the field of medical imaging

  1. Right is not always wrong: DTI and fMRI evidence for the reliance of reading comprehension on language-comprehension networks in the right hemisphere.

    Science.gov (United States)

    Horowitz-Kraus, Tzipi; Grainger, Molly; DiFrancesco, Mark; Vannest, Jennifer; Holland, Scott K

    2015-03-01

    The Simple View theory suggests that reading comprehension relies on automatic recognition of words combined with language comprehension. The goal of the current study was to examine the structural and functional connectivity in networks supporting reading comprehension and their relationship with language comprehension within 7-9 year old children using Diffusion Tensor Imaging (DTI) and fMRI during a Sentence Picture Matching task. Fractional Anisotropy (FA) values in the left and right Inferior Longitudinal Fasciculus (ILF) and Superior Longitudinal Fasciculus (SLF), known language-related tracts, were correlated from DTI data with scores from the Woodcock-Johnson III (WJ-III) Passage Comprehension sub-test. Brodmann areas most proximal to white-matter regions with significant correlation to Passage Comprehension scores were chosen as Regions-of-Interest (ROIs) and used as seeds in a functional connectivity analysis using the Sentence Picture Matching task. The correlation between percentile scores for the WJ-III Passage Comprehension subtest and the FA values in the right and left ILF and SLF indicated positive correlation in language-related ROIs, with greater distribution in the right hemisphere, which in turn showed strong connectivity in the fMRI data from the Sentence Picture Matching task. These results support the participation of the right hemisphere in reading comprehension and may provide physiologic support for a distinction between different types of reading comprehension deficits vs difficulties in technical reading.

  2. Combination of DTI and fMRI reveals the white matter changes correlating with the decline of default-mode network activity in Alzheimer's disease

    Science.gov (United States)

    Wu, Xianjun; Di, Qian; Li, Yao; Zhao, Xiaojie

    2009-02-01

    Recently, evidences from fMRI studies have shown that there was decreased activity among the default-mode network in Alzheimer's disease (AD), and DTI researches also demonstrated that demyelinations exist in white matter of AD patients. Therefore, combining these two MRI methods may help to reveal the relationship between white matter damages and alterations of the resting state functional connectivity network. In the present study, we tried to address this issue by means of correlation analysis between DTI and resting state fMRI images. The default-mode networks of AD and normal control groups were compared to find the areas with significantly declined activity firstly. Then, the white matter regions whose fractional anisotropy (FA) value correlated with this decline were located through multiple regressions between the FA values and the BOLD response of the default networks. Among these correlating white matter regions, those whose FA values also declined were found by a group comparison between AD patients and healthy elderly control subjects. Our results showed that the areas with decreased activity among default-mode network included left posterior cingulated cortex (PCC), left medial temporal gyrus et al. And the damaged white matter areas correlated with the default-mode network alterations were located around left sub-gyral temporal lobe. These changes may relate to the decreased connectivity between PCC and medial temporal lobe (MTL), and thus correlate with the deficiency of default-mode network activity.

  3. Evaluation of glymphatic system activity with the diffusion MR technique: diffusion tensor image analysis along the perivascular space (DTI-ALPS) in Alzheimer's disease cases.

    Science.gov (United States)

    Taoka, Toshiaki; Masutani, Yoshitaka; Kawai, Hisashi; Nakane, Toshiki; Matsuoka, Kiwamu; Yasuno, Fumihiko; Kishimoto, Toshifumi; Naganawa, Shinji

    2017-04-01

    The activity of the glymphatic system is impaired in animal models of Alzheimer's disease (AD). We evaluated the activity of the human glymphatic system in cases of AD with a diffusion-based technique called diffusion tensor image analysis along the perivascular space (DTI-ALPS). Diffusion tensor images were acquired to calculate diffusivities in the x, y, and z axes of the plane of the lateral ventricle body in 31 patients. We evaluated the diffusivity along the perivascular spaces as well as projection fibers and association fibers separately, to acquire an index for diffusivity along the perivascular space (ALPS-index) and correlated them with the mini mental state examinations (MMSE) score. We found a significant negative correlation between diffusivity along the projection fibers and association fibers. We also observed a significant positive correlation between diffusivity along perivascular spaces shown as ALPS-index and the MMSE score, indicating lower water diffusivity along the perivascular space in relation to AD severity. Activity of the glymphatic system may be evaluated with diffusion images. Lower diffusivity along the perivascular space on DTI-APLS seems to reflect impairment of the glymphatic system. This method may be useful for evaluating the activity of the glymphatic system.

  4. Multilevel Deficiency of White Matter Connectivity Networks in Alzheimer’s Disease: A Diffusion MRI Study with DTI and HARDI Models

    Directory of Open Access Journals (Sweden)

    Tao Wang

    2016-01-01

    Full Text Available Alzheimer’s disease (AD is the most common form of dementia in elderly people. It is an irreversible and progressive brain disease. In this paper, we utilized diffusion-weighted imaging (DWI to detect abnormal topological organization of white matter (WM structural networks. We compared the differences between WM connectivity characteristics at global, regional, and local levels in 26 patients with probable AD and 16 normal control (NC elderly subjects, using connectivity networks constructed with the diffusion tensor imaging (DTI model and the high angular resolution diffusion imaging (HARDI model, respectively. At the global level, we found that the WM structural networks of both AD and NC groups had a small-world topology; however, the AD group showed a significant decrease in both global and local efficiency, but an increase in clustering coefficient and the average shortest path length. We further found that the AD patients had significantly decreased nodal efficiency at the regional level, as well as weaker connections in multiple local cortical and subcortical regions, such as precuneus, temporal lobe, hippocampus, and thalamus. The HARDI model was found to be more advantageous than the DTI model, as it was more sensitive to the deficiencies in AD at all of the three levels.

  5. DTI scouting mission to Japan on trapped ions for measurement and enterprise (TIME) 26th-30th November 2001

    International Nuclear Information System (INIS)

    Klein, H.; Knight, D.; Plimmer, M.; Silver, J.

    2002-01-01

    This report describes the findings of the DTI sponsored scouting mission to Japan 'Trapped Ions for Measurement and Enterprise' (TIME). It focuses particularly on new optical frequency standards (for which trapped ions are strong candidates) and measurement of optical frequency standards using femtosecond comb laser systems. There has been a 'sea change' in optical frequency metrology using these measurement systems, and ensuing technical developments are moving quickly, with potential implications for telecommunications and photonics, navigation and ultimately for time measurement. The mission examined what the UK and Japan have in common in this field and the scope for future collaborations. It included visits to two national laboratories, the National Metrology Institute of Japan (NMIJ) and the Communications Research Laboratory (CRL), two companies, Anritsu and NTT, and discussions with staff at the University of Electrocommunications and Kyoto University. At the National Physical Laboratory (NPL) in the UK and elsewhere there have recently been developments of femtosecond comb laser systems, which have been used to measure the absolute frequencies of several optical frequency standards including several very stable ion- trap based standards. In Japan these measurement systems at the National Metrology Institute of Japan (NMIJ) have been used to measure the optical frequencies of iodine stabilised lasers, but trapped-ion based optical standards still need development. More detailed observations and conclusions include: a) The measurement opportunities offered by femtosecond laser comb technology were widely appreciated by scientists in Japan. b) Many of the laboratories we visited were very well equipped, in some cases better than those in the UK. For example NMIJ already had 5 femtosecond comb systems. c) A feasibility study on optical frequency standards and clocks was being started at CRL Koganei; future work would be likely to involve collaboration with the

  6. Alternatives for optimisation of rumen fermentation in ruminants

    Directory of Open Access Journals (Sweden)

    T. Slavov

    2017-06-01

    Full Text Available Abstract. The proper knowledge on the variety of events occurring in the rumen makes possible their optimisation with respect to the complete feed conversion and increasing the productive performance of ruminants. The inclusion of various dietary additives (supplements, biologically active substances, nutritional antibiotics, probiotics, enzymatic preparations, plant extracts etc. has an effect on the intensity and specific pathway of fermentation, and thus, on the general digestion and systemic metabolism. The optimisation of rumen digestion is a method with substantial potential for improving the efficiency of ruminant husbandry, increasing of quality of their produce and health maintenance.

  7. Separative power of an optimised concurrent gas centrifuge

    Energy Technology Data Exchange (ETDEWEB)

    Bogovalov, Sergey; Boman, Vladimir [National Research Nuclear University (MEPHI), Moscow (Russian Federation)

    2016-06-15

    The problem of separation of isotopes in a concurrent gas centrifuge is solved analytically for an arbitrary binary mixture of isotopes. The separative power of the optimised concurrent gas centrifuges for the uranium isotopes equals to δU = 12.7 (V/700 m/s)2(300 K/T)(L/1 m) kg·SWU/yr, where L and V are the length and linear velocity of the rotor of the gas centrifuge and T is the temperature. This equation agrees well with the empirically determined separative power of optimised counter-current gas centrifuges.

  8. MANAGEMENT OPTIMISATION OF MASS CUSTOMISATION MANUFACTURING USING COMPUTATIONAL INTELLIGENCE

    Directory of Open Access Journals (Sweden)

    Louwrens Butler

    2018-05-01

    Full Text Available Computational intelligence paradigms can be used for advanced manufacturing system optimisation. A static simulation model of an advanced manufacturing system was developed in order to simulate a manufacturing system. The purpose of this advanced manufacturing system was to mass-produce a customisable product range at a competitive cost. The aim of this study was to determine whether this new algorithm could produce a better performance than traditional optimisation methods. The algorithm produced a lower cost plan than that for a simulated annealing algorithm, and had a lower impact on the workforce.

  9. Optimising a shaft's geometry by applying genetic algorithms

    Directory of Open Access Journals (Sweden)

    María Alejandra Guzmán

    2005-05-01

    Full Text Available Many engnieering design tasks involve optimising several conflicting goals; these types of problem are known as Multiobjective Optimisation Problems (MOPs. Evolutionary techniques have proved to be an effective tool for finding solutions to these MOPs during the last decade, Variations on the basic generic algorithm have been particulary proposed by different researchers for finding rapid optimal solutions to MOPs. The NSGA (Non-dominated Sorting Generic Algorithm has been implemented in this paper for finding an optimal design for a shaft subjected to cyclic loads, the conflycting goals being minimum weight and minimum lateral deflection.

  10. Optimisation of BPMN Business Models via Model Checking

    DEFF Research Database (Denmark)

    Herbert, Luke Thomas; Sharp, Robin

    2013-01-01

    We present a framework for the optimisation of business processes modelled in the business process modelling language BPMN, which builds upon earlier work, where we developed a model checking based method for the analysis of BPMN models. We define a structure for expressing optimisation goals...... for synthesized BPMN components, based on probabilistic computation tree logic and real-valued reward structures of the BPMN model, allowing for the specification of complex quantitative goals. We here present a simple algorithm, inspired by concepts from evolutionary algorithms, which iteratively generates...

  11. The optimisation of wedge filters in radiotherapy of the prostate

    International Nuclear Information System (INIS)

    Oldham, Mark; Neal, Anthony J.; Webb, Steve

    1995-01-01

    A treatment plan optimisation algorithm has been applied to 12 patients with early prostate cancer in order to determine the optimum beam-weights and wedge angles for a standard conformal three-field treatment technique. The optimisation algorithm was based on fast-simulated-annealing using a cost function designed to achieve a uniform dose in the planning-target-volume (PTV) and to minimise the integral doses to the organs-at-risk. The algorithm has been applied to standard conformal three-field plans created by an experienced human planner, and run in three PLAN MODES: (1) where the wedge angles were fixed by the human planner and only the beam-weights were optimised; (2) where both the wedge angles and beam-weights were optimised; and (3) where both the wedge angles and beam-weights were optimised and a non-uniform dose was prescribed to the PTV. In the latter PLAN MODE, a uniform 100% dose was prescribed to all of the PTV except for that region that overlaps with the rectum where a lower (e.g., 90%) dose was prescribed. The resulting optimised plans have been compared with those of the human planner who found beam-weights by conventional forward planning techniques. Plans were compared on the basis of dose statistics, normal-tissue-complication-probability (NTCP) and tumour-control-probability (TCP). The results of the comparison showed that all three PLAN MODES produced plans with slightly higher TCP for the same rectal NTCP, than the human planner. The best results were observed for PLAN MODE 3, where an average increase in TCP of 0.73% (± 0.20, 95% confidence interval) was predicted by the biological models. This increase arises from a beneficial dose gradient which is produced across the tumour. Although the TCP gain is small it comes with no increase in treatment complexity, and could translate into increased cures given the large numbers of patients being referred. A study of the beam-weights and wedge angles chosen by the optimisation algorithm revealed

  12. Translating state-of-the-art spinal cord MRI techniques to clinical use: A systematic review of clinical studies utilizing DTI, MT, MWF, MRS, and fMRI.

    Science.gov (United States)

    Martin, Allan R; Aleksanderek, Izabela; Cohen-Adad, Julien; Tarmohamed, Zenovia; Tetreault, Lindsay; Smith, Nathaniel; Cadotte, David W; Crawley, Adrian; Ginsberg, Howard; Mikulis, David J; Fehlings, Michael G

    2016-01-01

    A recent meeting of international imaging experts sponsored by the International Spinal Research Trust (ISRT) and the Wings for Life Foundation identified 5 state-of-the-art MRI techniques with potential to transform the field of spinal cord imaging by elucidating elements of the microstructure and function: diffusion tensor imaging (DTI), magnetization transfer (MT), myelin water fraction (MWF), MR spectroscopy (MRS), and functional MRI (fMRI). However, the progress toward clinical translation of these techniques has not been established. A systematic review of the English literature was conducted using MEDLINE, MEDLINE-in-Progress, Embase, and Cochrane databases to identify all human studies that investigated utility, in terms of diagnosis, correlation with disability, and prediction of outcomes, of these promising techniques in pathologies affecting the spinal cord. Data regarding study design, subject characteristics, MRI methods, clinical measures of impairment, and analysis techniques were extracted and tabulated to identify trends and commonalities. The studies were assessed for risk of bias, and the overall quality of evidence was assessed for each specific finding using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework. A total of 6597 unique citations were identified in the database search, and after full-text review of 274 articles, a total of 104 relevant studies were identified for final inclusion (97% from the initial database search). Among these, 69 studies utilized DTI and 25 used MT, with both techniques showing an increased number of publications in recent years. The review also identified 1 MWF study, 11 MRS studies, and 8 fMRI studies. Most of the studies were exploratory in nature, lacking a priori hypotheses and showing a high (72%) or moderately high (20%) risk of bias, due to issues with study design, acquisition techniques, and analysis methods. The acquisitions for each technique varied widely across

  13. Credit price optimisation within retail banking

    African Journals Online (AJOL)

    2014-02-14

    Feb 14, 2014 ... function. Cross and Dixit [5] state that the key to customer-centric pricing is to set prices that accurately reflect the perceived value of products per customer segment, .... 1The interest rate at which commercial banks can borrow money from the Reserve Bank. ..... following additional parameters are required:.

  14. Cost modelling in maintenance strategy optimisation for infrastructure assets with limited data

    International Nuclear Information System (INIS)

    Zhang, Wenjuan; Wang, Wenbin

    2014-01-01

    Our paper reports on the use of cost modelling in maintenance strategy optimisation for infrastructure assets. We present an original approach: the possibility of modelling even when the data and information usually required are not sufficient in quantity and quality. Our method makes use of subjective expert knowledge, and requires information gathered for only a small sample of assets to start with. Bayes linear methods are adopted to combine the subjective expert knowledge with the sample data to estimate the unknown model parameters of the cost model. When new information becomes available, Bayes linear methods also prove useful in updating these estimates. We use a case study from the rail industry to demonstrate our methods. The optimal maintenance strategy is obtained via simulation based on the estimated model parameters and the strategy with the least unit time cost is identified. When the optimal strategy is not followed due to insufficient funding, the future costs of recovering the degraded asset condition are estimated

  15. Designing and optimising anaerobic digestion systems: A multi-objective non-linear goal programming approach

    International Nuclear Information System (INIS)

    Nixon, J.D.

    2016-01-01

    This paper presents a method for optimising the design parameters of an anaerobic digestion (AD) system by using first-order kinetics and multi-objective non-linear goal programming. A model is outlined that determines the ideal operating tank temperature and hydraulic retention time, based on objectives for minimising levelised cost of electricity, and maximising energy potential and feedstock mass reduction. The model is demonstrated for a continuously stirred tank reactor processing food waste in two case study locations. These locations are used to investigate the influence of different environmental and economic climates on optimal conditions. A sensitivity analysis is performed to further examine the variation in optimal results for different financial assumptions and objective weightings. The results identify the conditions for the preferred tank temperature to be in the psychrophilic, mesophilic or thermophilic range. For a tank temperature of 35 °C, ideal hydraulic retention times, in terms of achieving a minimum levelised electricity cost, were found to range from 29.9 to 33 days. Whilst there is a need for more detailed information on rate constants for use in first-order models, multi-objective optimisation modelling is considered to be a promising option for AD design. - Highlights: • Nonlinear goal programming is used to optimise anaerobic digestion systems. • Multiple objectives are set including minimising the levelised cost of electricity. • A model is developed and applied to case studies for the UK and India. • Optimal decisions are made for tank temperature and retention time. • A sensitivity analysis is carried out to investigate different model objectives.

  16. An optimisation framework for thermal energy storage integration in a residential heat pump heating system

    International Nuclear Information System (INIS)

    Renaldi, R.; Kiprakis, A.; Friedrich, D.

    2017-01-01

    Highlights: • An integrated framework for the optimal design of low carbon heating systems. • Development of a synthetic heat demand model with occupancy profiles. • Linear model of a heat pump with thermal energy storage heating system. • Evaluation of domestic heating system from generally available input parameters. • The lower carbon heating system can be cost competitive with conventional systems. - Abstract: Domestic heating has a large share in the UK total energy consumption and significant contribution to the greenhouse gas emissions since it is mainly fulfilled by fossil fuels. Therefore, decarbonising the heating system is essential and an option to achieve this is by heating system electrification through heat pumps (HP) installation in combination with renewable power generation. A potential increase in performance and flexibility can be achieved by pairing HP with thermal energy storage (TES), which allows the shifting of heat demand to off peak periods or periods with surplus renewable electricity. We present a design and operational optimisation model which is able to assess the performance of HP–TES relative to conventional heating systems. The optimisation is performed on a synthetic heat demand model which requires only the annual heat demand, temperature and occupancy profiles. The results show that the equipment and operational cost of a HP system without TES are significantly higher than for a conventional system. However, the integration of TES and time-of-use tariffs reduce the operational cost of the HP systems and in combination with the Renewable Heating Incentive make the HP systems cost competitive with conventional systems. The presented demand model and optimisation procedure will enable the design of low carbon district heating systems which integrate the heating system with the variable renewable electricity supply.

  17. Production of biosolid fuels from municipal sewage sludge: Technical and economic optimisation.

    Science.gov (United States)

    Wzorek, Małgorzata; Tańczuk, Mariusz

    2015-08-01

    The article presents the technical and economic analysis of the production of fuels from municipal sewage sludge. The analysis involved the production of two types of fuel compositions: sewage sludge with sawdust (PBT fuel) and sewage sludge with meat and bone meal (PBM fuel). The technology of the production line of these sewage fuels was proposed and analysed. The main objective of the study is to find the optimal production capacity. The optimisation analysis was performed for the adopted technical and economic parameters under Polish conditions. The objective function was set as a maximum of the net present value index and the optimisation procedure was carried out for the fuel production line input capacity from 0.5 to 3 t h(-1), using the search step 0.5 t h(-1). On the basis of technical and economic assumptions, economic efficiency indexes of the investment were determined for the case of optimal line productivity. The results of the optimisation analysis show that under appropriate conditions, such as prices of components and prices of produced fuels, the production of fuels from sewage sludge can be profitable. In the case of PBT fuel, calculated economic indexes show the best profitability for the capacity of a plant over 1.5 t h(-1) output, while production of PBM fuel is beneficial for a plant with the maximum of searched capacities: 3.0 t h(-1). Sensitivity analyses carried out during the investigation show that influence of both technical and economic assessments on the location of maximum of objective function (net present value) is significant. © The Author(s) 2015.

  18. Modelling and genetic algorithm based optimisation of inverse supply chain

    Science.gov (United States)

    Bányai, T.

    2009-04-01

    possible solution method. By the aid of analytical methods, the problem can not be solved, so a genetic algorithm based heuristic optimisation method was chosen to find the optimal solution. The input parameters of the optimisation are the followings: specific fixed, unit and environmental risk costs of the collection points of the inverse supply chain, specific warehousing and transportation costs and environmental risk costs of transportation. The output parameters are the followings: the number of objects in the different hierarchical levels of the collection system, infrastructure costs, logistics costs and environmental risk costs from used infrastructures, transportation and number of products recycled out of time. The next step of the research work was the application of the above mentioned method. The developed application makes it possible to define the input parameters of the real system, the graphical view of the chosen optimal solution in the case of the given input parameters, graphical view of the cost structure of the optimal solution, determination of the parameters of the algorithm (e.g. number of individuals, operators and termination conditions). The sensibility analysis of the objective function and the test results showed that the structure of the inverse supply chain depends on the proportion of the specific costs. Especially the proportion of the specific environmental risk costs influences the structure of the system and the number of objects at each hierarchical level of the collection system. The sensitivity analysis of the total cost function was performed in three cases. In the first case the effect of the proportion of specific infrastructure and logistics costs were analysed. If the infrastructure costs are significantly lower than the total costs of warehousing and transportation, then almost all objects of the first hierarchical level of the collection (collection directly from the users) were set up. In the other case of the proportion of

  19. A Monte-Carlo simulation framework for joint optimisation of image quality and patient dose in digital paediatric radiography

    International Nuclear Information System (INIS)

    Menser, Bernd; Manke, Dirk; Mentrup, Detlef; Neitzel, Ulrich

    2016-01-01

    In paediatric radiography, according to the as low as reasonably achievable (ALARA) principle, the imaging task should be performed with the lowest possible radiation dose. This paper describes a Monte-Carlo simulation framework for dose optimisation of imaging parameters in digital paediatric radiography. Patient models with high spatial resolution and organ segmentation enable the simultaneous evaluation of image quality and patient dose on the same simulated radiographic examination. The accuracy of the image simulation is analysed by comparing simulated and acquired images of technical phantoms. As a first application example, the framework is applied to optimise tube voltage and pre-filtration in newborn chest radiography. At equal patient dose, the highest CNR is obtained with low-kV settings in combination with copper filtration. (authors)

  20. Agent-Based Decision Control—How to Appreciate Multivariate Optimisation in Architecture

    DEFF Research Database (Denmark)

    Negendahl, Kristoffer; Perkov, Thomas Holmer; Kolarik, Jakub

    2015-01-01

    , the method is applied to a multivariate optimisation problem. The aim is specifically to demonstrate optimisation for entire building energy consumption, daylight distribution and capital cost. Based on the demonstrations Moth’s ability to find local minima is discussed. It is concluded that agent-based...... in the early design stage. The main focus is to demonstrate the optimisation method, which is done in two ways. Firstly, the newly developed agent-based optimisation algorithm named Moth is tested on three different single objective search spaces. Here Moth is compared to two evolutionary algorithms. Secondly...... optimisation algorithms like Moth open up for new uses of optimisation in the early design stage. With Moth the final outcome is less dependent on pre- and post-processing, and Moth allows user intervention during optimisation. Therefore, agent-based models for optimisation such as Moth can be a powerful...

  1. Multigrid Implementation of Cellular Automata for Topology Optimisation of Continuum Structures with Design Dependent loads

    NARCIS (Netherlands)

    Zakhama, R.

    2009-01-01

    Topology optimisation of continuum structures has become mature enough to be often applied in industry and continues to attract the attention of researchers and software companies in various engineering fields. Traditionally, most available algorithms for solving topology optimisation problems are

  2. Solving dynamic multi-objective problems with vector evaluated particle swarm optimisation

    CSIR Research Space (South Africa)

    Greeff, M

    2008-06-01

    Full Text Available Many optimisation problems are multi-objective and change dynamically. Many methods use a weighted average approach to the multiple objectives. This paper introduces the usage of the vector evaluated particle swarm optimiser (VEPSO) to solve dynamic...

  3. Optimisation of warpage on plastic injection moulding part using response surface methodology (RSM) and genetic algorithm method (GA)

    Science.gov (United States)

    Miza, A. T. N. A.; Shayfull, Z.; Nasir, S. M.; Fathullah, M.; Hazwan, M. H. M.

    2017-09-01

    In this study, Computer Aided Engineering was used for injection moulding simulation. The method of Design of experiment (DOE) was utilize according to the Latin Square orthogonal array. The relationship between the injection moulding parameters and warpage were identify based on the experimental data that used. Response Surface Methodology (RSM) was used as to validate the model accuracy. Then, the RSM and GA method were combine as to examine the optimum injection moulding process parameter. Therefore the optimisation of injection moulding is largely improve and the result shown an increasing accuracy and also reliability. The propose method by combining RSM and GA method also contribute in minimising the warpage from occur.

  4. SINGLE FIXED CRANE OPTIMISATION WITHIN A DISTRIBUTION CENTRE

    Directory of Open Access Journals (Sweden)

    J. Matthews

    2012-01-01

    Full Text Available

    ENGLISH ABSTRACT: This paper considersthe optimisation of the movement of a fixed crane operating in a single aisle of a distribution centre. The crane must move pallets in inventory between docking bays, storage locations, and picking lines. Both a static and a dynamic approach to the problem are presented. The optimisation is performed by means of tabu search, ant colony metaheuristics,and hybrids of these two methods. All these solution approaches were tested on real life data obtained from an operational distribution centre. Results indicate that the hybrid methods outperform the other approaches.

    AFRIKAANSE OPSOMMING: Die optimisering van die beweging van 'n vaste hyskraan in 'n enkele gang van 'n distribusiesentrum word in hierdie artikel beskou. Die hyskraan moet pallette vervoer tussen dokhokke, stoorposisies, en opmaaklyne. Beide 'n statiese en 'n dinamiese benadering tot die probleem word aangebied. Die optimisering word gedoen met behulp van tabu-soektogte, mierkolonieoptimisering,en hibriede van hierdie twee metodes. Al die oplossingsbenaderings is getoets met werklike data wat van 'n operasionele distribusiesentrum verkry is. Die resultate toon aan dat die hibriedmetodes die beste oplossings lewer.

  5. Formulation des betons autopla~ants : Optimisation du squelette ...

    African Journals Online (AJOL)

    Formulation des betons autopla~ants : Optimisation du squelette granulaire par la methode graphique de Dreux - Gorisse. Fatiha Boumaza - Zeraoulia* & Mourad Behim. Laboratoire Materiaux, Geo - Materiaux et Environnement - Departement de Genie Civil. Universite Badji Mokhtar Annaba - BP 12, 23000 Annaba - ...

  6. Development of an Optimised Losartan Potassium Press-Coated ...

    African Journals Online (AJOL)

    The optimised formulation was further characterized with Fourier-transform infrared spectroscopy (FTIR) and powder X-ray diffractometry (PXRD) to investigate any drug/excipient modifications/interactions. Results: The tensile strength values of all the PCT were between 1.12 and 1.23MNm-2 and friability was < 0.36 %.

  7. Statistical Optimisation of Fermentation Conditions for Citric Acid ...

    African Journals Online (AJOL)

    This study investigated the optimisation of fermentation conditions during citric acid production via solid state fermentation (SSF) of pineapple peels using Aspergillus niger. A three-variable, three-level Box-Behnken design (BBD) comprising 17 experimental runs was used to develop a statistical model for the fermentation ...

  8. Optimising the Blended Learning Environment: The Arab Open University Experience

    Science.gov (United States)

    Hamdi, Tahrir; Abu Qudais, Mohammed

    2018-01-01

    This paper will offer some insights into possible ways to optimise the blended learning environment based on experience with this modality of teaching at Arab Open University/Jordan branch and also by reflecting upon the results of several meta-analytical studies, which have shown blended learning environments to be more effective than their face…

  9. Comparing and Optimising Parallel Haskell Implementations for Multicore Machines

    DEFF Research Database (Denmark)

    Berthold, Jost; Marlow, Simon; Hammond, Kevin

    2009-01-01

    In this paper, we investigate the differences and tradeoffs imposed by two parallel Haskell dialects running on multicore machines. GpH and Eden are both constructed using the highly-optimising sequential GHC compiler, and share thread scheduling, and other elements, from a common code base. The ...

  10. Larval feeding inhibition assay – need for optimisation

    DEFF Research Database (Denmark)

    Azuhnwi, Blasius; Desrues, O.; Hoste, H.

    2013-01-01

    for this observed variation in results include: parasite (species/strain); material tested; or season. There is thus need to optimise LFIA to permit intra and inter-laboratory comparison of results. We investigate here, if changes in EC50 values occur over the patency phase of a nematode species using two test...

  11. A comparative study of marriage in honey bees optimisation (MBO ...

    African Journals Online (AJOL)

    2012-02-15

    Feb 15, 2012 ... In a typical mating, the queen mates with 7 to 20 drones. Each time the .... Honey bee mating optimisation model's pseudo-code ... for this analysis, which consists of 47 years of monthly time ... tive of Karkheh Reservoir is to control and regulate the flow of ..... Masters thesis, Maastricht University, Maastricht.

  12. Analysing the performance of dynamic multi-objective optimisation algorithms

    CSIR Research Space (South Africa)

    Helbig, M

    2013-06-01

    Full Text Available and the goal of the algorithm is to track a set of tradeoff solutions over time. Analysing the performance of a dynamic multi-objective optimisation algorithm (DMOA) is not a trivial task. For each environment (before a change occurs) the DMOA has to find a set...

  13. Optimisation of dialysate flow in on-line hemodiafiltration

    Directory of Open Access Journals (Sweden)

    Francisco Maduell

    2015-09-01

    Conclusion: Qd variations in OL-HDF do not change convective volume. A higher Qd was associated to a slightly increased urea clearance with no change being observed for medium and large molecules. Qd optimisation to the minimal level assuring an adequate dialysis dose and allowing water and dialysate use to be rationalised should be recommended.

  14. Day-ahead economic optimisation of energy storage

    NARCIS (Netherlands)

    Lampropoulos, I.; Garoufalis, P.; Bosch, van den P.P.J.; Groot, de R.J.W.; Kling, W.L.

    2014-01-01

    This article addresses the day-ahead economic optimisation of energy storage systems within the setting of electricity spot markets. The case study is about a lithium-ion battery system integrated in a low voltage distribution grid with residential customers and photovoltaic generation in the

  15. Optimisation of the image resolution of a positron emission tomograph

    International Nuclear Information System (INIS)

    Ziemons, K.

    1993-10-01

    The resolution and the respective signal-to-noise ratios of reconstructed pictures were a point of main interest of the work for optimisation of PET systems. Monte-Carlo modelling calculations were applied to derive possible improvements of the technical design or performance of the PET system. (DG) [de

  16. FISHRENT; Bio-economic simulation and optimisation model

    NARCIS (Netherlands)

    Salz, P.; Buisman, F.C.; Soma, K.; Frost, H.; Accadia, P.; Prellezo, R.

    2011-01-01

    Key findings: The FISHRENT model is a major step forward in bio-economic model-ling, combining features that have not been fully integrated in earlier models: 1- Incorporation of any number of species (or stock) and/or fleets 2- Integration of simulation and optimisation over a period of 25 years 3-

  17. Plant-wide performance optimisation – The refrigeration system case

    DEFF Research Database (Denmark)

    Green, Torben; Razavi-Far, Roozbeh; Izadi-Zamanabadi, Roozbeh

    2012-01-01

    applicationsin the process industry. The paper addresses the fact that dynamic performance of the system is important, to ensure optimal changes between different operation conditions. To enable optimisation of the dynamic controller behaviour a method for designing the required excitation signal is presented...

  18. Preconditioned stochastic gradient descent optimisation for monomodal image registration

    NARCIS (Netherlands)

    Klein, S.; Staring, M.; Andersson, J.P.; Pluim, J.P.W.; Fichtinger, G.; Martel, A.; Peters, T.

    2011-01-01

    We present a stochastic optimisation method for intensity-based monomodal image registration. The method is based on a Robbins-Monro stochastic gradient descent method with adaptive step size estimation, and adds a preconditioning matrix. The derivation of the pre-conditioner is based on the

  19. Optimisation of Hidden Markov Model using Baum–Welch algorithm

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 126; Issue 1. Optimisation of Hidden Markov Model using Baum–Welch algorithm for prediction of maximum and minimum temperature over Indian Himalaya. J C Joshi Tankeshwar Kumar Sunita Srivastava Divya Sachdeva. Volume 126 Issue 1 February 2017 ...

  20. optimisation of compressive strength of periwinkle shell aggregate

    African Journals Online (AJOL)

    user

    2017-01-01

    Jan 1, 2017 ... In this paper, a regression model is developed to predict and optimise the compressive strength of periwinkle shell aggregate concrete using Scheffe's regression theory. The results obtained from the derived regression model agreed favourably with the experimental data. The model was tested for ...

  1. Smart optimisation and sensitivity analysis in water distribution systems

    CSIR Research Space (South Africa)

    Page, Philip R

    2015-12-01

    Full Text Available optimisation of a water distribution system by keeping the average pressure unchanged as water demands change, by changing the speed of the pumps. Another application area considered, using the same mathematical notions, is the study of the sensitivity...

  2. Estimators for initial conditions for optimisation in learning hydraulic systems

    NARCIS (Netherlands)

    Post, W.J.A.E.M.; Burrows, C.R.; Edge, K.A.

    1998-01-01

    In Learning Hydraulic Systems (LHS1. developed at the Eindhoven University of Technology, a specialised optimisation routine is employed In order to reduce energy losses in hydraulic systems. Typical load situations which can be managed by LHS are variable cyclic loads, as can be observed In many

  3. An optimised portfolio management model, incorporating best practices

    OpenAIRE

    2015-01-01

    M.Ing. (Engineering Management) Driving sustainability, optimising return on investments and cultivating a competitive market advantage, are imperative for organisational success and growth. In order to achieve the business objectives and value proposition, effective management strategies must be efficiently implemented, monitored and controlled. Failure to do so ultimately result in; financial loss due to increased capital and operational expenditure, schedule slippages, substandard deliv...

  4. Optimisation of searches for Supersymmetry with the ATLAS detector

    Energy Technology Data Exchange (ETDEWEB)

    Zvolsky, Milan

    2012-01-15

    The ATLAS experiment is one of the four large experiments at the Large Hadron Collider which is specifically designed to search for the Higgs boson and physics beyond the Standard Model. The aim of this thesis is the optimisation of searches for Supersymmetry in decays with two leptons and missing transverse energy in the final state. Two different optimisation studies have been performed for two important analysis aspects: The final signal region selection and the choice of the trigger selection. In the first part of the analysis, a cut-based optimisation of signal regions is performed, maximising the signal for a minimal background contamination. By this, the signal yield can in parts be more than doubled. The second approach is to introduce di-lepton triggers which allow to lower the lepton transverse momentum threshold, thus enhancing the number of selected signal events significantly. The signal region optimisation was considered for the choice of the final event selection in the ATLAS di-lepton analyses. The trigger study contributed to the incorporation of di-lepton triggers to the ATLAS trigger menu. (orig.)

  5. Optimisation Study on the Production of Anaerobic Digestate ...

    African Journals Online (AJOL)

    Organic fraction of municipal solid waste (OFMSW) is a rich substrate for biogas and compost production. Anaerobic Digestate compost (ADC) is an organic fertilizer produced from stabilized residuals of anaerobic digestion of OFMSW. This paper reports the result of studies carried out to optimise the production of ADC from ...

  6. Optimising performance in steady state for a supermarket refrigeration system

    DEFF Research Database (Denmark)

    Green, Torben; Kinnaert, Michel; Razavi-Far, Roozbeh

    2012-01-01

    Using a supermarket refrigeration system as an illustrative example, the paper postulates that by appropriately utilising knowledge of plant operation, the plant wide performance can be optimised based on a small set of variables. Focusing on steady state operations, the total system performance...

  7. A Bayesian Approach for Sensor Optimisation in Impact Identification

    Directory of Open Access Journals (Sweden)

    Vincenzo Mallardo

    2016-11-01

    Full Text Available This paper presents a Bayesian approach for optimizing the position of sensors aimed at impact identification in composite structures under operational conditions. The uncertainty in the sensor data has been represented by statistical distributions of the recorded signals. An optimisation strategy based on the genetic algorithm is proposed to find the best sensor combination aimed at locating impacts on composite structures. A Bayesian-based objective function is adopted in the optimisation procedure as an indicator of the performance of meta-models developed for different sensor combinations to locate various impact events. To represent a real structure under operational load and to increase the reliability of the Structural Health Monitoring (SHM system, the probability of malfunctioning sensors is included in the optimisation. The reliability and the robustness of the procedure is tested with experimental and numerical examples. Finally, the proposed optimisation algorithm is applied to a composite stiffened panel for both the uniform and non-uniform probability of impact occurrence.

  8. Optimisation of selective breeding program for Nile tilapia (Oreochromis niloticus)

    NARCIS (Netherlands)

    Trong, T.Q.

    2013-01-01

    The aim of this thesis was to optimise the selective breeding program for Nile tilapia in the Mekong Delta region of Vietnam. Two breeding schemes, the “classic” BLUP scheme following the GIFT method (with pair mating) and a rotational mating scheme with own performance selection and

  9. Optimised cantilever biosensor with piezoresistive read-out

    DEFF Research Database (Denmark)

    Rasmussen, Peter; Thaysen, J.; Hansen, Ole

    2003-01-01

    We present a cantilever-based biochemical sensor with piezoresistive read-out which has been optimised for measuring surface stress. The resistors and the electrical wiring on the chip are encapsulated in low-pressure chemical vapor deposition (LPCVD) silicon nitride, so that the chip is well sui...

  10. Optimisation of Heterogeneous Migration Paths to High Bandwidth Home Connections

    NARCIS (Netherlands)

    Phillipson, F.

    2017-01-01

    Operators are building architectures and systems for delivering voice, audio, and data services at the required speed for now and in the future. For fixed access networks, this means in many countries a shift from copper based to fibre based access networks. This paper proposes a method to optimise

  11. Optimisation of wort production from rice malt using enzymes and ...

    African Journals Online (AJOL)

    Commercially, rice malt has never been successfully used in brewing because of its low free α-amino nitrogen (FAN) content. This study was designed to optimise rice malt replacement for barley malt in wort production and to improve FAN by adding α-amylase and protease. The response surface methodology (RSM) ...

  12. Optimisation of a novel trailing edge concept for a high lift device

    CSIR Research Space (South Africa)

    Botha, JDM

    2014-09-01

    Full Text Available A novel concept (referred to as the flap extension) is implemented on the leading edge of the flap of a three element high lift device. The concept is optimised using two optimisation approaches based on Genetic Algorithm optimisations. A zero order...

  13. Coil optimisation for transcranial magnetic stimulation in realistic head geometry.

    Science.gov (United States)

    Koponen, Lari M; Nieminen, Jaakko O; Mutanen, Tuomas P; Stenroos, Matti; Ilmoniemi, Risto J

    Transcranial magnetic stimulation (TMS) allows focal, non-invasive stimulation of the cortex. A TMS pulse is inherently weakly coupled to the cortex; thus, magnetic stimulation requires both high current and high voltage to reach sufficient intensity. These requirements limit, for example, the maximum repetition rate and the maximum number of consecutive pulses with the same coil due to the rise of its temperature. To develop methods to optimise, design, and manufacture energy-efficient TMS coils in realistic head geometry with an arbitrary overall coil shape. We derive a semi-analytical integration scheme for computing the magnetic field energy of an arbitrary surface current distribution, compute the electric field induced by this distribution with a boundary element method, and optimise a TMS coil for focal stimulation. Additionally, we introduce a method for manufacturing such a coil by using Litz wire and a coil former machined from polyvinyl chloride. We designed, manufactured, and validated an optimised TMS coil and applied it to brain stimulation. Our simulations indicate that this coil requires less than half the power of a commercial figure-of-eight coil, with a 41% reduction due to the optimised winding geometry and a partial contribution due to our thinner coil former and reduced conductor height. With the optimised coil, the resting motor threshold of abductor pollicis brevis was reached with the capacitor voltage below 600 V and peak current below 3000 A. The described method allows designing practical TMS coils that have considerably higher efficiency than conventional figure-of-eight coils. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Future aircraft cabins and design thinking: optimisation vs. win-win scenarios

    Directory of Open Access Journals (Sweden)

    A. Hall

    2013-06-01

    Full Text Available With projections indicating an increase in mobility over the next few decades and annual flight departures expected to rise to over 16 billion by 2050, there is a demand for the aviation industry and associated stakeholders to consider new forms of aircraft and technology. Customer requirements are recognized as a key driver in business. The airline is the principal customer for the aircraft manufacture. The passenger is, in turn, the airline's principal customer but they are just one of several stakeholders that include aviation authorities, airport operators, air-traffic control and security agencies. The passenger experience is a key differentiator used by airlines to attract and retain custom and the fuselage that defines the cabin envelope for the in-flight passenger experience and cabin design therefore receives significant attention for new aircraft, service updates and refurbishments. Decision making in design is crucial to arriving at viable and worthwhile cabin formats. Too little innovation will result in an aircraft manufacturer and airlines using its products falling behind its competitors. Too much may result in an over-extension with, for example, use of immature technologies that do not have the necessary reliability for a safety critical industry or sufficient value to justify the development effort. The multiple requirements associated with cabin design, can be viewed as an area for optimisation, accepting trade-offs between the various parameters. Good design, however, is often defined as developing a concept that resolves the contradictions and takes the solution towards a win-win scenario. Indeed our understanding and practice of design allows for behaviors that enhance design thinking through divergence and convergence, the use of abductive reasoning, experimentation and systems thinking. This paper explores and defines the challenges of designing the aircraft cabin of the future that will deliver on the multiple

  15. Global nuclear industry views: challenges arising from the evolution of the optimisation principle in radiological protection

    International Nuclear Information System (INIS)

    Saint-Pierre, S.

    2012-01-01

    Over the last few decades, the steady progress achieved in reducing planned exposures of both workers and the public has been admirable in the nuclear sector. However, the disproportionate focus on tiny public exposures and radioactive discharges associated with normal operations came at a high price, and the quasi-denial of a risk of major accident and related weaknesses in emergency preparedness and response came at an even higher price. Fukushima has unfortunately taught us that radiological protection (RP) for emergency and post-emergency situations can be much more than a simple evacuation that lasts 24–48 h, with people returning safely to their homes soon afterwards. On optimisation of emergency and post-emergency exposures, the only ‘show in town’ in terms of international RP policy improvements has been the issuance of the 2007 Recommendations of the International Commission on Radiological Protection (ICRP). However, no matter how genuine these improvements are, they have not been ‘road tested’ on the practical reality of severe accidents. Post-Fukushima, there is a compelling case to review the practical adequacy of key RP notions such as optimisation, evacuation, sheltering, and reference levels for workers and the public, and to amend these notions with a view to making the international RP system more useful in the event of a severe accident. On optimisation of planned exposures, the reality is that, nowadays, margins for further reductions of public doses in the nuclear sector are very small, and the smaller the dose, the greater the extra effort needed to reduce the dose further. If sufficient caution is not exercised in the use of RP notions such as dose constraints, there is a real risk of challenging nuclear power technologies beyond safety reasons. For nuclear new build, it is the optimisation of key operational parameters of nuclear power technologies (not RP) that is of paramount importance to improve their overall efficiency. In

  16. Global nuclear industry views: challenges arising from the evolution of the optimisation principle in radiological protection.

    Science.gov (United States)

    Saint-Pierre, S

    2012-01-01

    Over the last few decades, the steady progress achieved in reducing planned exposures of both workers and the public has been admirable in the nuclear sector. However, the disproportionate focus on tiny public exposures and radioactive discharges associated with normal operations came at a high price, and the quasi-denial of a risk of major accident and related weaknesses in emergency preparedness and response came at an even higher price. Fukushima has unfortunately taught us that radiological protection (RP) for emergency and post-emergency situations can be much more than a simple evacuation that lasts 24-48 h, with people returning safely to their homes soon afterwards. On optimisation of emergency and post-emergency exposures, the only 'show in town' in terms of international RP policy improvements has been the issuance of the 2007 Recommendations of the International Commission on Radiological Protection (ICRP). However, no matter how genuine these improvements are, they have not been 'road tested' on the practical reality of severe accidents. Post-Fukushima, there is a compelling case to review the practical adequacy of key RP notions such as optimisation, evacuation, sheltering, and reference levels for workers and the public, and to amend these notions with a view to making the international RP system more useful in the event of a severe accident. On optimisation of planned exposures, the reality is that, nowadays, margins for further reductions of public doses in the nuclear sector are very small, and the smaller the dose, the greater the extra effort needed to reduce the dose further. If sufficient caution is not exercised in the use of RP notions such as dose constraints, there is a real risk of challenging nuclear power technologies beyond safety reasons. For nuclear new build, it is the optimisation of key operational parameters of nuclear power technologies (not RP) that is of paramount importance to improve their overall efficiency. In pursuing

  17. Image Quality and Patient Dose Optimisation in Mammography in Slovakia

    International Nuclear Information System (INIS)

    Horvathova, M.; Nikodemova, D.; Prikazska, M.

    2003-01-01

    Breast cancer represents also in Slovakia the greatest cancer risk for women, with great incidence and mortality. Conventional film-screen mammography is still the primary breast imaging modality with increasing number of mammography units and mammography examinations. From the radiation protection point of view achievement of good practice in mammography department by implementation of quality assurance play an important role for reduction of patients doses. Introduction of QA needs trained and experienced staff and requires close collaboration between radiologists, medical physicist and radiographers. At the beginning of nineties at the Institute of Preventive and Clinical Medicine we started with a survey of mean glandular doses at 15 existing mammography units in the country. On the basis of a questionnaire in the year 1991 were performed 10 488 mammography examinations, where due to out of date mammography units the mean glandular dose reached more as 3 mGy. In the following years the claim to the modern mammography units kept growing and in the year 1999 the total number of 63 mammography units were operating in Slovakia providing about 101 471 mammography examinations. According to the alarming increase of the number of mammography examinations it is absolutely necessary to work out criteria and principles for Quality Control at mammography workplaces in our country and make it obligatory for the staff of all mammography units. Summarising the CRP results it can be stated that they: 1) Initiated the suggestion of unified QA/QC criteria in mammography and the urgent need to implement them into the national program of radiology image quality improvement; 2) Remitted on unhomogenity not only in the equipment outfit but also in the procedure of evaluation of the measured parameters and imaging quality; 3) Revealed the shortcomings in the everyday practice of mammography units which can be removed only by comprehensive by training of personal in imaging radiology

  18. Optimising cardiac/angiographic digital images using a Butternut as the image quality phantom

    International Nuclear Information System (INIS)

    Bibbo, G.; Balman, D.

    2008-01-01

    Full text: Digital images, whether produced by image intensifiers, flat panels or computed radiography imaging plates, have a broad dynamic range and, thus, there is a need to adjust the exposure parameters of the imaging protocols to obtain diagnostic images without over exposing patients. The default exposure techniques of protocols delivered with the imaging equipment are in general set to produce high quality images at the expense of high radiation doses to patients. Ideally, these protocols should be optimised for best possible image quality at the lowest possible patient dose, particularly for paediatric patients. Manufacturers of equipment do not generally supply paediatric protocols and, thus, the default settings of the adult protocols have to be adjusted for paediatric patients. Optimising imaging protocols is not a trivial matter and, without a suitable phantom, it is difficult and time consuming. Commercial phantoms are commonly used to optimise adult protocols, but these are made of dry materials such as perspex, Teflon, aluminium, dry bone as in dry skulls, or a combination of these materials. The problem with these phantoms is that the features on their images are artificial, not simulating any characteristics of patients' anatomic details. In optimising paediatric protocols for our new cardiac/angiographic Siemens Biplane Digital Imaging System, we searched for a paediatric phantom with moisture content, and found that the humble butternut pumpkin (cucurbita moschate) from the squash family makes a good paediatric phantom, particularly, when it is injected with contrast. The part of the butternut that is useful as a phantom is the pulp, i.e., the part that contains the seeds. This is also the part where the contrast is injected. The image of the pulp contains structures that are natural as the butternut is the fruit of a living plant. The image of the seeds is suitable for low-level contrast detectability while fine structures enhanced by the

  19. Optimisation of ultrasonic-assisted extraction of phenolic compounds, antioxidants, and anthocyanins from sugar beet molasses.

    Science.gov (United States)

    Chen, Mingshun; Zhao, Yi; Yu, Shujuan

    2015-04-01

    Response surface methodology was used to optimise experimental conditions for ultrasonic-assisted extraction (UAE) of functional components from sugar beet molasses. The central composite design (CCD) was used for the optimisation of extraction parameters in terms of total phenolic contents, antioxidant activities and anthocyanins. Result suggested the optimal conditions obtained by RSM for UAE from sugar beet molasses were as follows: HCl concentration 1.55-1.72 mol/L, ethanol concentration 57-63% (v/v), extraction temperature 41-48 °C, and extraction time 66-73 min. In the optimal conditions, the experimental total phenolic contents were 17.36 mg GAE/100mL, antioxidant activity was 16.66 mg TE/g, and total anthocyanins were 31.81 mg/100g of the sugar beet molasses extract, which were well matched the predicted values. Teen compounds, i.e. gallic acid, vanillin, hydroxybenzoic acid, syringic acid, cyanidin-3-O-rutinoside, cyanidin-3-O-glucoside, catechin, delphinidin-3-O-rutinoside, delphinidin-3-O-glucuronide and ferulic acid were determined by HPLC-DAD-MS/MS in sugar beet molasses. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Optimising electron holography in the presence of partial coherence and instrument instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Shery L.Y., E-mail: shery.chang@fz-juelich.de; Dwyer, Christian, E-mail: c.dwyer@fz-juelich.de; Boothroyd, Chris B.; Dunin-Borkowski, Rafal E.

    2015-04-15

    Off-axis electron holography provides a direct means of retrieving the phase of the wavefield in a transmission electron microscope, enabling measurement of electric and magnetic fields at length scales from microns to nanometers. To maximise the accuracy of the technique, it is important to acquire holograms using experimental conditions that optimise the phase resolution for a given spatial resolution. These conditions are determined by a number of competing parameters, especially the spatial coherence and the instrument instabilities. Here, we describe a simple, yet accurate, model for predicting the dose rate and exposure time that give the best phase resolution in a single hologram. Experimental studies were undertaken to verify the model of spatial coherence and instrument instabilities that are required for the optimisation. The model is applicable to electron holography in both standard mode and Lorentz mode, and it is relatively simple to apply. - Highlights: • We describe a simple, yet accurate, model for predicting the best phase resolution in off-axis electron holography. • Calibration of the model requires only two series of blank holograms; an intensity sequence and a time sequence. • The model can predict the optimum dose rate and exposure time for any given combination of biprism voltage and magnification. • The model is applicable in both standard mode and Lorentz mode, using either round or elliptical illumination.

  1. Optimisation of ultrasound-assisted osmotic dehydration of sweet potato (Ipomea batatas) using response surface methodology.

    Science.gov (United States)

    Oladejo, Ayobami Olayemi; Ma, Haile

    2016-08-01

    Sweet potato is a highly nutritious tuber crop that is rich in β-carotene. Osmotic dehydration is a pretreatment method for drying of fruit and vegetables. Recently, ultrasound technology has been applied in food processing because of its numerous advantages which include time saving, little damage to the quality of the food. Thus, there is need to investigate and optimise the process parameters [frequency (20-50 kHz), time (10-30 min) and sucrose concentration (20-60% w/v)] for ultrasound-assisted osmotic dehydration of sweet potato using response surface methodology. The optimised values obtained were frequency of 33.93 kHz, time of 30 min and sucrose concentration of 35.69% (w/v) to give predicted values of 21.62, 4.40 and 17.23% for water loss, solid gain and weight reduction, respectively. The water loss and weight reduction increased when the ultrasound frequency increased from 20 to 35 kHz and then decreased as the frequency increased from 35 to 50 kHz. The results from this work show that low ultrasound frequency favours the osmotic dehydration of sweet potato and also reduces the use of raw material (sucrose) needed for the osmotic dehydration of sweet potato. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  2. Optimisation of chemical solution deposition of indium tin oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sunde, Tor Olav Løveng; Einarsrud, Mari-Ann; Grande, Tor, E-mail: grande@ntnu.no

    2014-12-31

    An environmentally friendly aqueous sol–gel process has been optimised to deposit indium tin oxide (ITO) thin films, aiming to improve the film properties and reduce the deposition costs. It was demonstrated how parameters such as cation concentration and viscosity could be applied to modify the physical properties of the sol and thereby reduce the need for multiple coatings to yield films with sufficient conductivity. The conductivity of the thin films was enhanced by adjusting the heat treatment temperature and atmosphere. Both increasing the heat treatment temperature of the films from 530 to 800 °C and annealing in reducing atmosphere significantly improved the electrical conductivity, and conductivities close to the state of the art sputtered ITO films were obtained. A pronounced decreased conductivity was observed after exposing the thin films to air and the thermal reduction and ageing of the film was studied by in situ conductivity measurements. - Highlights: • Spin coating of indium tin oxide using an aqueous solution was optimised. • The conductivity was enhanced by thermal annealing in reducing atmosphere. • The conductivity of is comparable to the conductivity of sputtered films. • A relaxation process in the reduced thin film was observed after exposure in air.

  3. Optimised resource construction for verifiable quantum computation

    International Nuclear Information System (INIS)

    Kashefi, Elham; Wallden, Petros

    2017-01-01

    Recent developments have brought the possibility of achieving scalable quantum networks and quantum devices closer. From the computational point of view these emerging technologies become relevant when they are no longer classically simulatable. Hence a pressing challenge is the construction of practical methods to verify the correctness of the outcome produced by universal or non-universal quantum devices. A promising approach that has been extensively explored is the scheme of verification via encryption through blind quantum computation. We present here a new construction that simplifies the required resources for any such verifiable protocol. We obtain an overhead that is linear in the size of the input (computation), while the security parameter remains independent of the size of the computation and can be made exponentially small (with a small extra cost). Furthermore our construction is generic and could be applied to any universal or non-universal scheme with a given underlying graph. (paper)

  4. Altered microstructural connectivity of the superior and middle cerebellar peduncles are related to motor dysfunction in children with diffuse periventricular leucomalacia born preterm: A DTI tractography study

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shanshan, E-mail: jelly_66@126.com; Fan, Guo Guang, E-mail: cjr.fanguoguang@vip.163.com; Xu, Ke, E-mail: cjr.xuke@vip.163.com; Wang, Ci, E-mail: xiangxuehai19850224@yahoo.cn

    2014-06-15

    Purpose: To investigate the microstructural integrity of superior cerebellar peduncles (SCP) and middle cerebellar peduncles (MCP) by using DTI tractography method, and further to detect whether the microstructural integrity of these major cerebellar pathways is related to motor function in children with diffuse periventricular leucomalacia (PVL) born preterm. Materials and methods: 46 children with diffuse PVL (30 males and 16 females; age range 3–48 months; mean age 22.4 ± 6.7 months; mean gestational age 30.5 ± 2.2 weeks) and 40 healthy controls (27 males and 13 females; age range 3.5–48 months; mean age 22.1 ± 5.8 months) were enrolled in this study. DTI outcome measurements, fractional anisotropy (FA), for the SCP, MCP and cortical spinal tract (CST) were calculated. The gross motor function classification system (GMFCS) was used for assessing motor functions. Results: Compared to the controls, patients with diffuse PVL had a significantly lower FA in bilateral SCP, MCP and CST. There was a significant negative correlation between GMFCS levels and FA in bilateral SCP, MCP and CST in the patients group. In addition, significant inverse correlation of FA value was found between not only the contralateral but also the ipsilateral CST and SCP/MCP. Conclusions: These findings suggest that the injury of SCP and MCP may contribute to the motor dysfunction of diffuse PVL. Moreover, the correlations we found between supratentorial and subtentorial injured white matter extend our knowledge about the cerebro-cerebellar white matter interaction in children with diffuse PVL.

  5. Left hemisphere fractional anisotropy increase in noise-induced tinnitus: a diffusion tensor imaging (DTI) study of white matter tracts in the brain.

    Science.gov (United States)

    Benson, Randall R; Gattu, Ramtilak; Cacace, Anthony T

    2014-03-01

    Diffusion tensor imaging (DTI) is a contemporary neuroimaging modality used to study connectivity patterns and microstructure of white matter tracts in the brain. The use of DTI in the study of tinnitus is a relatively unexplored methodology with no studies focusing specifically on tinnitus induced by noise exposure. In this investigation, participants were two groups of adults matched for etiology, age, and degree of peripheral hearing loss, but differed by the presence or absence (+/-) of tinnitus. It is assumed that matching individuals on the basis of peripheral hearing loss, allows for differentiating changes in white matter microstructure due to hearing loss from changes due to the effects of chronic tinnitus. Alterations in white matter tracts, using the fractional anisotropy (FA) metric, which measures directional diffusion of water, were quantified using tract-based spatial statistics (TBSS) with additional details provided by in vivo probabilistic tractography. Our results indicate that 10 voxel clusters differentiated the two groups, including 9 with higher FA in the group with tinnitus. A decrease in FA was found for a single cluster in the group with tinnitus. However, seven of the 9 clusters with higher FA were in left hemisphere thalamic, frontal, and parietal white matter. These foci were localized to the anterior thalamic radiations and the inferior and superior longitudinal fasciculi. The two right-sided clusters with increased FA were located in the inferior fronto-occipital fasciculus and superior longitudinal fasciculus. The only decrease in FA for the tinnitus-positive group was found in the superior longitudinal fasciculus of the left parietal lobe. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Combined DTI Tractography and Functional MRI Study of the Language Connectome in Healthy Volunteers: Extensive Mapping of White Matter Fascicles and Cortical Activations.

    Directory of Open Access Journals (Sweden)

    François Vassal

    Full Text Available Despite a better understanding of brain language organization into large-scale cortical networks, the underlying white matter (WM connectivity is still not mastered. Here we combined diffusion tensor imaging (DTI fiber tracking (FT and language functional magnetic resonance imaging (fMRI in twenty healthy subjects to gain new insights into the macroscopic structural connectivity of language. Eight putative WM fascicles for language were probed using a deterministic DTI-FT technique: the arcuate fascicle (AF, superior longitudinal fascicle (SLF, uncinate fascicle (UF, temporo-occipital fascicle, inferior fronto-occipital fascicle (IFOF, middle longitudinal fascicle (MdLF, frontal aslant fascicle and operculopremotor fascicle. Specific measurements (i.e. volume, length, fractional anisotropy and precise cortical terminations were derived for each WM fascicle within both hemispheres. Connections between these WM fascicles and fMRI activations were studied to determine which WM fascicles are related to language. WM fascicle volumes showed asymmetries: leftward for the AF, temporoparietal segment of SLF and UF, and rightward for the frontoparietal segment of the SLF. The lateralization of the AF, IFOF and MdLF extended to differences in patterns of anatomical connections, which may relate to specific hemispheric abilities. The leftward asymmetry of the AF was correlated to the leftward asymmetry of fMRI activations, suggesting that the lateralization of the AF is a structural substrate of hemispheric language dominance. We found consistent connections between fMRI activations and terminations of the eight WM fascicles, providing a detailed description of the language connectome. WM fascicle terminations were also observed beyond fMRI-confirmed language areas and reached numerous cortical areas involved in different functional brain networks. These findings suggest that the reported WM fascicles are not exclusively involved in language and might be

  7. The neuroanatomy of subthreshold depressive symptoms in Huntington's disease: a combined diffusion tensor imaging (DTI) and voxel-based morphometry (VBM) study.

    Science.gov (United States)

    Sprengelmeyer, R; Orth, M; Müller, H-P; Wolf, R C; Grön, G; Depping, M S; Kassubek, J; Justo, D; Rees, E M; Haider, S; Cole, J H; Hobbs, N Z; Roos, R A C; Dürr, A; Tabrizi, S J; Süssmuth, S D; Landwehrmeyer, G B

    2014-07-01

    Depressive symptoms are prominent psychopathological features of Huntington's disease (HD), making a negative impact on social functioning and well-being. We compared the frequencies of a history of depression, previous suicide attempts and current subthreshold depression between 61 early-stage HD participants and 40 matched controls. The HD group was then split based on the overall HD group's median Hospital Anxiety and Depression Scale-depression score into a group of 30 non-depressed participants (mean 0.8, s.d. = 0.7) and a group of 31 participants with subthreshold depressive symptoms (mean 7.3, s.d. = 3.5) to explore the neuroanatomy underlying subthreshold depressive symptoms in HD using voxel-based morphometry (VBM) and diffusion tensor imaging (DTI). Frequencies of history of depression, previous suicide attempts or current subthreshold depressive symptoms were higher in HD than in controls. The severity of current depressive symptoms was also higher in HD, but not associated with the severity of HD motor signs or disease burden. Compared with the non-depressed HD group DTI revealed lower fractional anisotropy (FA) values in the frontal cortex, anterior cingulate cortex, insula and cerebellum of the HD group with subthreshold depressive symptoms. In contrast, VBM measures were similar in both HD groups. A history of depression, the severity of HD motor signs or disease burden did not correlate with FA values of these regions. Current subthreshold depressive symptoms in early HD are associated with microstructural changes - without concomitant brain volume loss - in brain regions known to be involved in major depressive disorder, but not those typically associated with HD pathology.

  8. The efficiency of retrospective artifact correction methods in improving the statistical power of between-group differences in spinal cord DTI.

    Science.gov (United States)

    David, Gergely; Freund, Patrick; Mohammadi, Siawoosh

    2017-09-01

    Diffusion tensor imaging (DTI) is a promising approach for investigating the white matter microstructure of the spinal cord. However, it suffers from severe susceptibility, physiological, and instrumental artifacts present in the cord. Retrospective correction techniques are popular approaches to reduce these artifacts, because they are widely applicable and do not increase scan time. In this paper, we present a novel outlier rejection approach (reliability masking) which is designed to supplement existing correction approaches by excluding irreversibly corrupted and thus unreliable data points from the DTI index maps. Then, we investigate how chains of retrospective correction techniques including (i) registration, (ii) registration and robust fitting, and (iii) registration, robust fitting, and reliability masking affect the statistical power of a previously reported finding of lower fractional anisotropy values in the posterior column and lateral corticospinal tracts in cervical spondylotic myelopathy (CSM) patients. While established post-processing steps had small effect on the statistical power of the clinical finding (slice-wise registration: -0.5%, robust fitting: +0.6%), adding reliability masking to the post-processing chain increased it by 4.7%. Interestingly, reliability masking and registration affected the t-score metric differently: while the gain in statistical power due to reliability masking was mainly driven by decreased variability in both groups, registration slightly increased variability. In conclusion, reliability masking is particularly attractive for neuroscience and clinical research studies, as it increases statistical power by reducing group variability and thus provides a cost-efficient alternative to increasing the group size. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  9. Altered microstructural connectivity of the superior and middle cerebellar peduncles are related to motor dysfunction in children with diffuse periventricular leucomalacia born preterm: A DTI tractography study

    International Nuclear Information System (INIS)

    Wang, Shanshan; Fan, Guo Guang; Xu, Ke; Wang, Ci

    2014-01-01

    Purpose: To investigate the microstructural integrity of superior cerebellar peduncles (SCP) and middle cerebellar peduncles (MCP) by using DTI tractography method, and further to detect whether the microstructural integrity of these major cerebellar pathways is related to motor function in children with diffuse periventricular leucomalacia (PVL) born preterm. Materials and methods: 46 children with diffuse PVL (30 males and 16 females; age range 3–48 months; mean age 22.4 ± 6.7 months; mean gestational age 30.5 ± 2.2 weeks) and 40 healthy controls (27 males and 13 females; age range 3.5–48 months; mean age 22.1 ± 5.8 months) were enrolled in this study. DTI outcome measurements, fractional anisotropy (FA), for the SCP, MCP and cortical spinal tract (CST) were calculated. The gross motor function classification system (GMFCS) was used for assessing motor functions. Results: Compared to the controls, patients with diffuse PVL had a significantly lower FA in bilateral SCP, MCP and CST. There was a significant negative correlation between GMFCS levels and FA in bilateral SCP, MCP and CST in the patients group. In addition, significant inverse correlation of FA value was found between not only the contralateral but also the ipsilateral CST and SCP/MCP. Conclusions: These findings suggest that the injury of SCP and MCP may contribute to the motor dysfunction of diffuse PVL. Moreover, the correlations we found between supratentorial and subtentorial injured white matter extend our knowledge about the cerebro-cerebellar white matter interaction in children with diffuse PVL

  10. Combined DTI Tractography and Functional MRI Study of the Language Connectome in Healthy Volunteers: Extensive Mapping of White Matter Fascicles and Cortical Activations.

    Science.gov (United States)

    Vassal, François; Schneider, Fabien; Boutet, Claire; Jean, Betty; Sontheimer, Anna; Lemaire, Jean-Jacques

    2016-01-01

    Despite a better understanding of brain language organization into large-scale cortical networks, the underlying white matter (WM) connectivity is still not mastered. Here we combined diffusion tensor imaging (DTI) fiber tracking (FT) and language functional magnetic resonance imaging (fMRI) in twenty healthy subjects to gain new insights into the macroscopic structural connectivity of language. Eight putative WM fascicles for language were probed using a deterministic DTI-FT technique: the arcuate fascicle (AF), superior longitudinal fascicle (SLF), uncinate fascicle (UF), temporo-occipital fascicle, inferior fronto-occipital fascicle (IFOF), middle longitudinal fascicle (MdLF), frontal aslant fascicle and operculopremotor fascicle. Specific measurements (i.e. volume, length, fractional anisotropy) and precise cortical terminations were derived for each WM fascicle within both hemispheres. Connections between these WM fascicles and fMRI activations were studied to determine which WM fascicles are related to language. WM fascicle volumes showed asymmetries: leftward for the AF, temporoparietal segment of SLF and UF, and rightward for the frontoparietal segment of the SLF. The lateralization of the AF, IFOF and MdLF extended to differences in patterns of anatomical connections, which may relate to specific hemispheric abilities. The leftward asymmetry of the AF was correlated to the leftward asymmetry of fMRI activations, suggesting that the lateralization of the AF is a structural substrate of hemispheric language dominance. We found consistent connections between fMRI activations and terminations of the eight WM fascicles, providing a detailed description of the language connectome. WM fascicle terminations were also observed beyond fMRI-confirmed language areas and reached numerous cortical areas involved in different functional brain networks. These findings suggest that the reported WM fascicles are not exclusively involved in language and might be related to

  11. Site-specific optimisation of the countermeasure structure on rehabilitation of radioactive contaminated territories

    International Nuclear Information System (INIS)

    Yatsalo, B.I.; Okhrimenko, D.V.; Lisyanski, B.G.; Okhrimenko, I.V.; Mirzeabassov, O.A.

    2000-01-01

    The use of 'soft' countermeasures (CMs) (agricultural CMs, some administrative ones, except for relocation/resettlement and some 'strong' measures on restriction of living conditions) allows considering the radiological and economic parameters for assessing their effectiveness. In this case cost-benefit analysis (CBA) or some its modification are used. However, the determination of various radiological and economic parameters (and their combination) is not enough for making final decisions on countermeasure implementation. All radiological, ecological and economic characteristics and other expert knowledge, corresponding standards and regulations should be taken into account, and many of them may not be used very often in analytical methods directly. The approaches to evaluating strong' CMs are based, as a rule, on expert judgements (MAUA, M-Crit). However, in practice they can lead to any result given in advance or to a choice of an weighted solution which does not comply with opinions by most experts due to considerable range of expert opinions and subjective weights for chosen attributes/criteria. Implementation of CMs on rehabilitation of contaminated territories should be based on the radiation protection principles. However, these principles are declared only when realising CMs on rehabilitation of contaminated territories after the Chernobyl accident. In practice some national or departmental standards are used and principles of justification'/'optimisation' are not examined. Taking into consideration a complex character of tasks on CM analysis and comparison of various alternatives it is quite necessary to use up-to-date computer decision support systems (DSSs). One of the systems which is directly intended for site-specific rehabilitation of territories subjected to radioactive contamination after the Chernobyl accident is the PRANA DSS. A key block of PRANA is 'analysis and optimisation of CMs structure'. It is intended for : -determination of territories

  12. Site-specific optimisation of the countermeasure structure on rehabilitation of radioactive contaminated territories

    Energy Technology Data Exchange (ETDEWEB)

    Yatsalo, B.I.; Okhrimenko, D.V.; Lisyanski, B.G.; Okhrimenko, I.V.; Mirzeabassov, O.A. [Obninsk Institute of Nuclear Power Engineering, Obninsk, Kaluga (Russian Federation)

    2000-05-01

    The use of 'soft' countermeasures (CMs) (agricultural CMs, some administrative ones, except for relocation/resettlement and some 'strong' measures on restriction of living conditions) allows considering the radiological and economic parameters for assessing their effectiveness. In this case cost-benefit analysis (CBA) or some its modification are used. However, the determination of various radiological and economic parameters (and their combination) is not enough for making final decisions on countermeasure implementation. All radiological, ecological and economic characteristics and other expert knowledge, corresponding standards and regulations should be taken into account, and many of them may not be used very often in analytical methods directly. The approaches to evaluating strong' CMs are based, as a rule, on expert judgements (MAUA, M-Crit). However, in practice they can lead to any result given in advance or to a choice of an weighted solution which does not comply with opinions by most experts due to considerable range of expert opinions and subjective weights for chosen attributes/criteria. Implementation of CMs on rehabilitation of contaminated territories should be based on the radiation protection principles. However, these principles are declared only when realising CMs on rehabilitation of contaminated territories after the Chernobyl accident. In practice some national or departmental standards are used and principles of justification'/'optimisation' are not examined. Taking into consideration a complex character of tasks on CM analysis and comparison of various alternatives it is quite necessary to use up-to-date computer decision support systems (DSSs). One of the systems which is directly intended for site-specific rehabilitation of territories subjected to radioactive contamination after the Chernobyl accident is the PRANA DSS. A key block of PRANA is 'analysis and optimisation of CMs structure

  13. Application of statistical experimental design for optimisation of bioinsecticides production by sporeless Bacillus thuringiensis strain on cheap medium.

    Science.gov (United States)

    Ben Khedher, Saoussen; Jaoua, Samir; Zouari, Nabil

    2013-01-01

    In order to overproduce bioinsecticides production by a sporeless Bacillus thuringiensis strain, an optimal composition of a cheap medium was defined using a response surface methodology. In a first step, a Plackett-Burman design used to evaluate the effects of eight medium components on delta-endotoxin production showed that starch, soya bean and sodium chloride exhibited significant effects on bioinsecticides production. In a second step, these parameters were selected for further optimisation by central composite design. The obtained results revealed that the optimum culture medium for delta-endotoxin production consists of 30 g L(-1) starch, 30 g L(-1) soya bean and 9 g L(-1) sodium chloride. When compared to the basal production medium, an improvement in delta-endotoxin production up to 50% was noted. Moreover, relative toxin yield of sporeless Bacillus thuringiensis S22 was improved markedly by using optimised cheap medium (148.5 mg delta-endotoxins per g starch) when compared to the yield obtained in the basal medium (94.46 mg delta-endotoxins per g starch). Therefore, the use of optimised culture cheap medium appeared to be a good alternative for a low cost production of sporeless Bacillus thuringiensis bioinsecticides at industrial scale which is of great importance in practical point of view.

  14. Application of statistical experimental design for optimisation of bioinsecticides production by sporeless Bacillus thuringiensis strain on cheap medium

    Directory of Open Access Journals (Sweden)

    Saoussen Ben Khedher

    2013-09-01

    Full Text Available In order to overproduce bioinsecticides production by a sporeless Bacillus thuringiensis strain, an optimal composition of a cheap medium was defined using a response surface methodology. In a first step, a Plackett-Burman design used to evaluate the effects of eight medium components on delta-endotoxin production showed that starch, soya bean and sodium chloride exhibited significant effects on bioinsecticides production. In a second step, these parameters were selected for further optimisation by central composite design. The obtained results revealed that the optimum culture medium for delta-endotoxin production consists of 30 g L-1 starch, 30 g L-1 soya bean and 9g L-1 sodium chloride. When compared to the basal production medium, an improvement in delta-endotoxin production up to 50% was noted. Moreover, relative toxin yield of sporeless Bacillus thuringiensis S22 was improved markedly by using optimised cheap medium (148.5 mg delta-endotoxins per g starch when compared to the yield obtained in the basal medium (94.46 mg delta-endotoxins per g starch. Therefore, the use of optimised culture cheap medium appeared to be a good alternative for a low cost production of sporeless Bacillus thuringiensis bioinsecticides at industrial scale which is of great importance in practical point of view.

  15. A framework for the computer-aided planning and optimisation of manufacturing processes for components with functional graded properties

    Science.gov (United States)

    Biermann, D.; Gausemeier, J.; Heim, H.-P.; Hess, S.; Petersen, M.; Ries, A.; Wagner, T.

    2014-05-01

    In this contribution a framework for the computer-aided planning and optimisation of functional graded components is presented. The framework is divided into three modules - the "Component Description", the "Expert System" for the synthetisation of several process chains and the "Modelling and Process Chain Optimisation". The Component Description module enhances a standard computer-aided design (CAD) model by a voxel-based representation of the graded properties. The Expert System synthesises process steps stored in the knowledge base to generate several alternative process chains. Each process chain is capable of producing components according to the enhanced CAD model and usually consists of a sequence of heating-, cooling-, and forming processes. The dependencies between the component and the applied manufacturing processes as well as between the processes themselves need to be considered. The Expert System utilises an ontology for that purpose. The ontology represents all dependencies in a structured way and connects the information of the knowledge base via relations. The third module performs the evaluation of the generated process chains. To accomplish this, the parameters of each process are optimised with respect to the component specification, whereby the result of the best parameterisation is used as representative value. Finally, the process chain which is capable of manufacturing a functionally graded component in an optimal way regarding to the property distributions of the component description is presented by means of a dedicated specification technique.

  16. Optimisation of X-ray examinations: General principles and an Irish perspective

    International Nuclear Information System (INIS)

    Matthews, Kate; Brennan, Patrick C.

    2009-01-01

    In Ireland, the European Medical Exposures Directive [Council Directive 97/43] was enacted into national law in Statutory Instrument 478 of 2002. This series of three review articles discusses the status of justification and optimisation of X-ray examinations nationally, and progress with the establishment of Irish diagnostic reference levels. In this second article, literature relating to optimisation issues arising in SI 478 of 2002 is reviewed. Optimisation associated with X-ray equipment and optimisation during day-to-day practice are considered. Optimisation proposals found in published research are summarised, and indicate the complex nature of optimisation. A paucity of current, research-based guidance documentation is identified. This is needed in order to support a range of professional staff in their practical implementation of optimisation.

  17. Mesh dependence in PDE-constrained optimisation an application in tidal turbine array layouts

    CERN Document Server

    Schwedes, Tobias; Funke, Simon W; Piggott, Matthew D

    2017-01-01

    This book provides an introduction to PDE-constrained optimisation using finite elements and the adjoint approach. The practical impact of the mathematical insights presented here are demonstrated using the realistic scenario of the optimal placement of marine power turbines, thereby illustrating the real-world relevance of best-practice Hilbert space aware approaches to PDE-constrained optimisation problems. Many optimisation problems that arise in a real-world context are constrained by partial differential equations (PDEs). That is, the system whose configuration is to be optimised follows physical laws given by PDEs. This book describes general Hilbert space formulations of optimisation algorithms, thereby facilitating optimisations whose controls are functions of space. It demonstrates the importance of methods that respect the Hilbert space structure of the problem by analysing the mathematical drawbacks of failing to do so. The approaches considered are illustrated using the optimisation problem arisin...

  18. Optimising imaging parameters for post mortem MR imaging of the human brain

    Energy Technology Data Exchange (ETDEWEB)

    Blamire, A.M.; Rowe, J.G.; Styles, P. [MRC Magnetic Resonance Spectroscopy Unit, Dept. of Biochemistry, Univ. of Oxford (United Kingdom); McDonald, B. [MRC Schizophrenia Research Group, Dept. of Neuropathology, Radcliffe Infirmary, Oxford (United Kingdom)

    1999-11-01

    Purpose: MR imaging of post mortem brains has the potential to yield volumetric information and define the extent of structural changes prior to pathological examination. Although standard T2-weighted clinical imaging sequences have been used for the examination of formalin-fixed brains, these protocols may not yield optimum contrast. We examined the effect of varying durations of formalin fixation on the transverse relaxation time (T2) and the tissue spin density. Material and Methods: Three post mortem brains were examined weekly during formalin fixation from the unfixed state to 35 days fixation. Standard MR spin-echo imaging was used at 5 echo times (20-100 ms) to calculate transverse relaxation time (T2) and spin density. Results: T2 decreased significantly (ANOVA, p<0.001) in both grey and white matter by 7 days fixation and there was a further (but non-significant) trend towards lower values between7 and 35 days. Grey and white matter T2 times converged with fixation. Conversely, the grey to white matter spin density ratio increased from 1.19{+-}0.01 to 1.54{+-}0.06 over five weeks of fixation. Conclusion: Our results suggest that spin density-weighted imaging sequences would provide improved grey to white matter contrast over T2-weighted sequences. (orig.)

  19. Bee Parameter Determination via Weighted Centriod Modified Simplex and Constrained Response Surface Optimisation Methods

    OpenAIRE

    P. Luangpaiboon

    2011-01-01

    Various intelligences and inspirations have been adopted into the iterative searching process called as meta-heuristics. They intelligently perform the exploration and exploitation in the solution domain space aiming to efficiently seek near optimal solutions. In this work, the bee algorithm, inspired by the natural foraging behaviour of honey bees, was adapted to find the near optimal solutions of the transportation management system, dynamic multi-zone dispatching. This...

  20. Evaluating phantom image quality parameters to optimise patient radiation dose in dental digital radiology.

    Science.gov (United States)

    Gonzalez, Luciano; Vano, Eliseo; Fernandez, Ramon; Ziraldo, Viviana; Delgado, Jaime; Delgado, Victor; Moro, Javier; Ubeda, Carlos

    2012-08-01

    Our objective was to obtain images of a predictable level of quality using an intraoral X-ray system with digital imaging, avoiding patient overexposure. A polymethylmethacrylate (PMMA) physical test phantom was imaged at different exposure times and at various PMMA thicknesses using a dental imaging coupled charge device. Two identical regions of interest (ROIs) were chosen in every image file, and quality was numerically evaluated by measuring high-contrast spatial resolutions, low-contrast thresholds and signal-to-noise ratios. In addition, three practitioners proposed personal quality scores by image inspection. Numerical contents in the ROIs, related to the image quality, were plotted against exposure time. From here, a simple expression linking the exposure time with the thickness to obtain images of comparable quality was deduced. As a result, the optimum exposure time for imaging with a predictable level of quality can be inferred. The potential effect could imply savings above 1000 man Sv, roughly 20 % of the collective dose due to dental imaging, over a population of 1540 millions.

  1. Optimisation of cultivation parameters in photobioreactors for microalgae cultivation using the A-stat technique

    NARCIS (Netherlands)

    Barbosa, M.J.; Hoogakker, J.; Wijffels, R.H.

    2003-01-01

    Light availability inside the reactor is often the bottleneck in microalgal cultivation and for this reason much attention is being given to light limited growth kinetics of microalgae, aiming at the increase of productivity in photobioreactors. Steady-state culture characteristics are commonly used

  2. FEL gain optimisation and spontaneous radiation

    Energy Technology Data Exchange (ETDEWEB)

    Bali, L.M.; Srivastava, A.; Pandya, T.P. [Lucknow Univ. (India)] [and others

    1995-12-31

    Colson have evaluated FEL gains for small deviations from perfect electron beam injection, with radiation of the same polarisation as that of the wiggler fields. We find that for optimum gain the polarisation of the optical field should be the same as that of the spontaneous emission under these conditions. With a helical wiggler the axial oscillations resulting from small departures from perfect electron beam injection lead to injection dependent unequal amplitudes and phases of the spontaneous radiation in the two transverse directions. Viewed along the axis therefore the spontaneous emission is elliptically polarised. The azimuth of the ellipse varies with the difference of phase of the two transverse components of spontaneous emission but the eccentricity remains the same. With planar wigglers the spontaneous emission viewed in the axial direction is linearly polarised, again with an injection dependent azimuth. For optimum coherent gain of a radiation field its polarisation characteristics must be the same as those of the spontaneous radiation with both types of wiggler. Thus, with a helical wiggler and the data reported earlier, an increase of 10% in the FEL gain at the fundamental frequency and of 11% at the fifth harmonic has been calculated in the small gain per pass limit. Larger enhancements in gain may result from more favourable values of input parameters.

  3. Study of the costs of offshore wind generation: a report to the Renewables Advisory Board and DTI (Dept. of Trade and Industry)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-03-12

    This study was commissioned by the Department of Trade and Industry (DTI) to provide an estimation of the future costs of offshore wind generation, and the potential for cost reductions in the future. Currently, given the strong market demand for wind turbines and cables, project costs are rising for an industry that is already borderline in terms of economical viability. Hence, the industry and the Government needs to be convinced that there is potential to make this industry more economically attractive and to ensure that it is able to contribute to meet future UK targets of energy from renewable sources. The focus of this report is on the Offshore Design Engineering Ltd. (ODE) Offshore Wind Farm Cost Model, which was specifically developed to allow specific estimates of future wind generation costs to be produced and to allow the user to carry out 'what if' scenarios for changes in the primary trends. Following extensive research six parameters were identified has having the most significant effect on overall project costs. Those are supply and demand, steel costs, copper costs, the effect of learning, research and development and supply and demand of turbines. These trends have been developed based on, where applicable, historical data, previous study work and an extensive Industry Research carried out by ODE. Three trend lines were identified for each trend, a normalised trend line which ODE perceived would be the most likely, and an upper and lower bound. The cost model is based on a level 2 schedule with calculated and fixed costs and durations to individual activities. These costs and durations have been based on information garnered from representatives right across the industry from developers to financiers to cable manufacturers to installation contractors. In parallel with the cost model, a structural study was run with the aim of identifying foundation weights with varying water depths and soil types. It was determined that the monopile, the

  4. Current NRPB recommendations on optimisation of protection of workers

    International Nuclear Information System (INIS)

    Wrixon, A.D.

    1994-01-01

    The National Radiological Protection Board is required by Ministerial Direction to provide advice on the relevance of the recommendations of the International Commission on Radiological Protection to the UK. Its advice was published in the Spring of 1993 after a period of consultation. In this article, which formed the basis of a presentation at an SRP Meeting on 29 April 1994, the Board's advice on the optimisation of protection of workers is explored and presented in the context of the developments in the understanding of the principle that have taken place in recent years. The most significant developments are the realisation that implementation of the principle is an essential function of good management and the recognition that the interests of the individual are not sufficiently taken into account by the dose limits alone but doses to individuals should be both constrained and optimised. (author)

  5. Optimised Design and Analysis of All-Optical Networks

    DEFF Research Database (Denmark)

    Glenstrup, Arne John

    2002-01-01

    through various experiments and is shown to produce good results and to be able to scale up to networks of realistic sizes. A novel method, subpath wavelength grouping, for routing connections in a multigranular all-optical network where several wavelengths can be grouped and switched at band and fibre......This PhD thesis presents a suite of methods for optimising design and for analysing blocking probabilities of all-optical networks. It thus contributes methodical knowledge to the field of computer assisted planning of optical networks. A two-stage greenfield optical network design optimiser...... is developed, based on shortest-path algorithms and a comparatively new metaheuristic called simulated allocation. It is able to handle design of all-optical mesh networks with optical cross-connects, considers duct as well as fibre and node costs, and can also design protected networks. The method is assessed...

  6. Optimised mounting conditions for poly (ether sulfone) in radiation detection.

    Science.gov (United States)

    Nakamura, Hidehito; Shirakawa, Yoshiyuki; Sato, Nobuhiro; Yamada, Tatsuya; Kitamura, Hisashi; Takahashi, Sentaro

    2014-09-01

    Poly (ether sulfone) (PES) is a candidate for use as a scintillation material in radiation detection. Its characteristics, such as its emission spectrum and its effective refractive index (based on the emission spectrum), directly affect the propagation of light generated to external photodetectors. It is also important to examine the presence of background radiation sources in manufactured PES. Here, we optimise the optical coupling and surface treatment of the PES, and characterise its background. Optical grease was used to enhance the optical coupling between the PES and the photodetector; absorption by the grease of short-wavelength light emitted from PES was negligible. Diffuse reflection induced by surface roughening increased the light yield for PES, despite the high effective refractive index. Background radiation derived from the PES sample and its impurities was negligible above the ambient, natural level. Overall, these results serve to optimise the mounting conditions for PES in radiation detection. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Optimisation of patient and staff exposure in interventional cardiology

    International Nuclear Information System (INIS)

    Padovani, R.; Malisan, M.R.; Bernardi, G.; Vano, E.; Neofotistou, V.

    2001-01-01

    The Council Directive of the European Community 97/43/Euratom (MED) deals with the health protection of individuals against dangers of ionising radiation in relation to medical exposure, and also focuses attention on some special practices (Art. 9), including interventional radiology, a technique involving high doses to the patient. The paper presents the European approach to optimisation of exposure in interventional cardiology. The DIMOND research consortium (DIMOND: Digital Imaging: Measures for Optimising Radiological Information Content and Dose) is working to develop quality criteria for cineangiographic images, to develop procedures for the classification of complexity of therapeutic and diagnostic procedures and to derive reference levels, related also to procedure complexity. DIMOND project also includes aspects of equipment characteristics and performance and content of training in radiation protection of personnel working in interventional radiology field. (author)

  8. Biomass supply chain optimisation for Organosolv-based biorefineries.

    Science.gov (United States)

    Giarola, Sara; Patel, Mayank; Shah, Nilay

    2014-05-01

    This work aims at providing a Mixed Integer Linear Programming modelling framework to help define planning strategies for the development of sustainable biorefineries. The up-scaling of an Organosolv biorefinery was addressed via optimisation of the whole system economics. Three real world case studies were addressed to show the high-level flexibility and wide applicability of the tool to model different biomass typologies (i.e. forest fellings, cereal residues and energy crops) and supply strategies. Model outcomes have revealed how supply chain optimisation techniques could help shed light on the development of sustainable biorefineries. Feedstock quality, quantity, temporal and geographical availability are crucial to determine biorefinery location and the cost-efficient way to supply the feedstock to the plant. Storage costs are relevant for biorefineries based on cereal stubble, while wood supply chains present dominant pretreatment operations costs. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Computed tomography dose optimisation in cystic fibrosis: A review.

    LENUS (Irish Health Repository)

    Ferris, Helena

    2016-04-28

    Cystic fibrosis (CF) is the most common autosomal recessive disease of the Caucasian population worldwide, with respiratory disease remaining the most relevant source of morbidity and mortality. Computed tomography (CT) is frequently used for monitoring disease complications and progression. Over the last fifteen years there has been a six-fold increase in the use of CT, which has lead to a growing concern in relation to cumulative radiation exposure. The challenge to the medical profession is to identify dose reduction strategies that meet acceptable image quality, but fulfil the requirements of a diagnostic quality CT. Dose-optimisation, particularly in CT, is essential as it reduces the chances of patients receiving cumulative radiation doses in excess of 100 mSv, a dose deemed significant by the United Nations Scientific Committee on the Effects of Atomic Radiation. This review article explores the current trends in imaging in CF with particular emphasis on new developments in dose optimisation.

  10. Necessity and complexity of order picking routing optimisation based on pallet loading features

    Directory of Open Access Journals (Sweden)

    Bódis Tamás

    2017-12-01

    Full Text Available Order picking is the most labour-intensive and costly activity of warehouses. The main challenges of its improvement are the synchronisation of warehouse layout, storage assignment policy, routing, zoning, and batching. Furthermore, the competitiveness of the warehouse depends on how it adapts to the unique customer demands and product parameters and the changes. The operators usually have to manage the picking sequence based on best practices taking into consideration the product stacking factors and minimising the lead time. It is usually necessary to support the operators by making e ective decisions. Researchers of the pallet loading problem, bin packing problem, and order picking optimisation provide a wide horizon of solutions but their results are rarely synchronised.

  11. Optimisation and characterisation of tungsten thick coatings on copper based alloy substrates

    Science.gov (United States)

    Riccardi, B.; Montanari, R.; Casadei, M.; Costanza, G.; Filacchioni, G.; Moriani, A.

    2006-06-01

    Tungsten is a promising armour material for plasma facing components of nuclear fusion reactors because of its low sputter rate and favourable thermo-mechanical properties. Among all the techniques able to realise W armours, plasma spray looks particularly attractive owing to its simplicity and low cost. The present work concerns the optimisation of spraying parameters aimed at 4-5 mm thick W coating on copper-chromium-zirconium (Cu,Cr,Zr) alloy substrates. Characterisation of coatings was performed in order to assess microstructure, impurity content, density, tensile strength, adhesion strength, thermal conductivity and thermal expansion coefficient. The work performed has demonstrated the feasibility of thick W coatings on flat and curved geometries. These coatings appear as a reliable armour for medium heat flux plasma facing component.

  12. Optimisation and characterisation of tungsten thick coatings on copper based alloy substrates

    International Nuclear Information System (INIS)

    Riccardi, B.; Montanari, R.; Casadei, M.; Costanza, G.; Filacchioni, G.; Moriani, A.

    2006-01-01

    Tungsten is a promising armour material for plasma facing components of nuclear fusion reactors because of its low sputter rate and favourable thermo-mechanical properties. Among all the techniques able to realise W armours, plasma spray looks particularly attractive owing to its simplicity and low cost. The present work concerns the optimisation of spraying parameters aimed at 4-5 mm thick W coating on copper-chromium-zirconium (Cu,Cr,Zr) alloy substrates. Characterisation of coatings was performed in order to assess microstructure, impurity content, density, tensile strength, adhesion strength, thermal conductivity and thermal expansion coefficient. The work performed has demonstrated the feasibility of thick W coatings on flat and curved geometries. These coatings appear as a reliable armour for medium heat flux plasma facing component

  13. Optimisation and characterisation of tungsten thick coatings on copper based alloy substrates

    Energy Technology Data Exchange (ETDEWEB)

    Riccardi, B. [Associazione Euratom-ENEA sulla Fusione, CR Frascati, P.B. 65 00044 Frascati, Roma (Italy)]. E-mail: riccardi@frascati.enea.it; Montanari, R. [Dipartimento di Ingegneria Meccanica, Universita di Roma, Tor Vergata, 00133 Roma (Italy); Casadei, M. [Centro Sviluppo Materiali, 00100 Roma (Italy); Costanza, G. [Dipartimento di Ingegneria Meccanica, Universita di Roma, Tor Vergata, 00133 Roma (Italy); Filacchioni, G. [ENEA CR Casaccia, I-00060 S. M. di Galeria, Roma (Italy); Moriani, A. [Associazione Euratom-ENEA sulla Fusione, CR Frascati, P.B. 65 00044 Frascati, Roma (Italy)

    2006-06-30

    Tungsten is a promising armour material for plasma facing components of nuclear fusion reactors because of its low sputter rate and favourable thermo-mechanical properties. Among all the techniques able to realise W armours, plasma spray looks particularly attractive owing to its simplicity and low cost. The present work concerns the optimisation of spraying parameters aimed at 4-5 mm thick W coating on copper-chromium-zirconium (Cu,Cr,Zr) alloy substrates. Characterisation of coatings was performed in order to assess microstructure, impurity content, density, tensile strength, adhesion strength, thermal conductivity and thermal expansion coefficient. The work performed has demonstrated the feasibility of thick W coatings on flat and curved geometries. These coatings appear as a reliable armour for medium heat flux plasma facing component.

  14. Ant colony optimisation for scheduling of flexible job shop with multi-resources requirements

    Directory of Open Access Journals (Sweden)

    Kalinowski Krzysztof

    2017-01-01

    Full Text Available The paper presents application of ant colony optimisation algorithm for scheduling multi-resources operations in flexible job shop type of production systems. Operations that require the participation of two or more resources are common in industrial practice, when planning are subject not only machines, but also other additional resources (personnel, tools, etc.. Resource requirements of operation are indicated indirectly by resource groups. The most important parameters of the resource model and resource groups are also described. A basic assumptions for ant colony algorithm used for scheduling in the considered model with multiresources requirements of operations is discussed. The main result of the research is the schema of metaheuristic that enables searching best-score solutions in manufacturing systems satisfying presented constraints.

  15. Use of ultrasonic baths for analytical applications: a new approach for optimisation conditions

    Directory of Open Access Journals (Sweden)

    Nascentes Clésia C.

    2001-01-01

    Full Text Available Optimisation conditions for obtaining maximum cavitation intensity in ultrasonic baths are proposed using a simple and fast method. Parameters such as water volume, temperature, detergent concentration, horizontal and vertical positions, number of tubes in the bath, sonication time and bath water substitution were studied. The results obtained for both baths studied (Neytech and Cole-Parmer lead to the following conditions for maximum cavitation intensity: 1 L of water at room temperature, 0.2 % (v/v of detergent, central position on the bottom of the tank. Only one tube at a time should be used inside the bath during the ultrasound application. The cavitation intensity was linear with the sonication time up to 10 minutes and the water substitution during the sonication improved reproducibility. This system using continuous water change makes possible the sonication of 6 consecutive samples, without changes in the water volume.

  16. Energy balance of the optimised CVT-hybrid-driveline

    Energy Technology Data Exchange (ETDEWEB)

    Hoehn, Bernd-Robert; Pflaum, Hermann; Lechner, Claus [Forschungsstelle fuer Zahnraeder und Getriebebau, Technische Univ. Muenchen, Garching (Germany)

    2009-07-01

    Funded by the DFG (German Research Foundation) and some industry partners like GM Powertrain Europe, ZF, EPCOS the Optimised CVT-Hybrid was developed at Technische Universitaet Muenchen in close collaboration with the industry and is currently under scientific investigation. Designed as a parallel hybrid vehicle the Optimised CVT-Hybrid combines a series-production diesel engine with a small electric motor. The core element of the driveline is a two range continuously variable transmission (i{radical}i-transmission), which is based on a chain variator. By a special shifting process without interruption of traction force the ratio range of the chain variator is used twice; thereby a wide transmission-ratio spread is achieved by low complexity. Thus the transmission provides a large pull-away ratio for the small electric motor and a fuel-efficient overdrive ratio for the ic-engine. Instead of heavy and space-consuming accumulators a small efficient package of double layer capacitors (UltraCaps) is used for electric energy and power storage. The driveline management is done by an optimised vehicle controller. Within the scope of the research project two prototype drivelines were manufactured. One driveline is integrated into an Opel Vectra Caravan and is available for investigations at the roller dynamometer and in the actual road traffic. The second hybrid driveline is assembled at the powertrain test rig of the FZG for detailed analysis of system behaviour and fuel consumption. Based on measurements of standardised driving cycles system behaviour, fuel consumption and a detailed energy balance of the Optimised CVT-Hybrid are presented. In comparison to the series-production vehicle the fuel savings are shown. (orig.)

  17. Optimising metadata workflows in a distributed information environment

    OpenAIRE

    Robertson, R. John; Barton, Jane

    2005-01-01

    The different purposes present within a distributed information environment create the potential for repositories to enhance their metadata by capitalising on the diversity of metadata available for any given object. This paper presents three conceptual reference models required to achieve this optimisation of metadata workflow: the ecology of repositories, the object lifecycle model, and the metadata lifecycle model. It suggests a methodology for developing the metadata lifecycle model, and ...

  18. Optimising training data for ANNs with Genetic Algorithms

    OpenAIRE

    Kamp , R. G.; Savenije , H. H. G.

    2006-01-01

    International audience; Artificial Neural Networks (ANNs) have proved to be good modelling tools in hydrology for rainfall-runoff modelling and hydraulic flow modelling. Representative datasets are necessary for the training phase in which the ANN learns the model's input-output relations. Good and representative training data is not always available. In this publication Genetic Algorithms (GA) are used to optimise training datasets. The approach is tested with an existing hydraulic model in ...

  19. Optimising training data for ANNs with Genetic Algorithms

    OpenAIRE

    R. G. Kamp; R. G. Kamp; H. H. G. Savenije

    2006-01-01

    Artificial Neural Networks (ANNs) have proved to be good modelling tools in hydrology for rainfall-runoff modelling and hydraulic flow modelling. Representative datasets are necessary for the training phase in which the ANN learns the model's input-output relations. Good and representative training data is not always available. In this publication Genetic Algorithms (GA) are used to optimise training datasets. The approach is tested with an existing hydraulic model in The Netherlands. An...

  20. A review of patient dose and optimisation methods in adult and paediatric CT scanning

    International Nuclear Information System (INIS)

    Dougeni, E.; Faulkner, K.; Panayiotakis, G.

    2012-01-01

    Highlights: ► CT scanning frequency has grown with the development of new clinical applications. ► Up to 32-fold dose variation was observed for similar type of procedures. ► Scanning parameters should be optimised for patient size and clinical indication. ► Cancer risks knowledge amongst physicians of certain specialties was poor. ► A significant number of non-indicated CT scans could be eliminated. - Abstract: An increasing number of publications and international reports on computed tomography (CT) have addressed important issues on optimised imaging practice and patient dose. This is partially due to recent technological developments as well as to the striking rise in the number of CT scans being requested. CT imaging has extended its role to newer applications, such as cardiac CT, CT colonography, angiography and urology. The proportion of paediatric patients undergoing CT scans has also increased. The published scientific literature was reviewed to collect information regarding effective dose levels during the most common CT examinations in adults and paediatrics. Large dose variations were observed (up to 32-fold) with some individual sites exceeding the recommended dose reference levels, indicating a large potential to reduce dose. Current estimates on radiation-related cancer risks are alarming. CT doses account for about 70% of collective dose in the UK and are amongst the highest in diagnostic radiology, however the majority of physicians underestimate the risk, demonstrating a decreased level of awareness. Exposure parameters are not always adjusted appropriately to the clinical question or to patient size, especially for children. Dose reduction techniques, such as tube-current modulation, low-tube voltage protocols, prospective echocardiography-triggered coronary angiography and iterative reconstruction algorithms can substantially decrease doses. An overview of optimisation studies is provided. The justification principle is discussed along