2,335 research outputs found
Production of Acetic Acid in Kraft Pulp Mill Biorefinery Using Bi-Polar Membrane Electrodialysis
The objective of this dissertation was to develop a process for the production of acetic acid in kraft mills. Acetyl groups in hardwood can be hydrolyzed using alkali at 50 °C. The product from this process contains about 15 g/L of sodium acetate and was determined to be suitable for the production of acetic acid.
Experiments performed using aqueous sodium acetate to evaluate the ability of electrodialysis (ED) to separate and concentrate sodium acetate showed that sodium acetate can be concentrated up to 275 g/L starting with an initial concentration of 17 g/L. The transport of water with sodium and acetate ions through ED membranes limited the maximum obtainable concentration.
To avoid the deleterious effects of white liquor on ED, selectivity experiments were performed using synthetic oxidized white liquor extract. These experiments showed a decrease in the efficiency of ED process due to the presence of sodium carbonate and sodium sulphate in the extract. Hence, it was concluded that caustic should be used as the extraction solvent.
Bi-polar electrodialysis (BPMED) experiments performed using sodium acetate showed that up to 200-280 g/L of acetic acid can be produced using BPMED. Although higher concentrations of sodium hydroxide can also be produced using BPMED, 30 g/L concentration was considered to be sufficient for recycle to the extraction process.
Feed and bleed mode BPMED experiments were performed to determine the current efficiencies and the suitable inlet concentration of sodium acetate for the production of up to 200 g/L of acetic acid. Both feed and bleed mode and batch experiments showed that the current density was the major driving force for BPMED.
Two types of concentrated wood extracts; namely (1) clarified and (2) unclarified were prepared with and without the lignin removal pre-treatment, respectively. The results of the ED and BPMED experiments performed using these extracts were similar to those of the synthetic sodium acetate. A major difference involved an increase of about 15% in electric energy consumption arising from the transport of formate, lactate and glycolate salts. The color of the anionic membranes slightly changed after processing unclarified extract through ED and BPMED
An athletic approach to studying perception-action integration: Does sport-specific training, and the impact of injury, influence how individuals visually guide navigation?
The objective of this thesis was to investigate perception-action integration capabilities of individuals during a choice navigation task. This task assessed navigation strategies in open space while individuals avoided colliding with two vertical obstacles that created a body-scaled, horizontal gap, at three varying obstacle distances from the starting location (3m, 5m, 7m). The two studies completed in this thesis employed the same paradigm to assess the hypothesized group differences. Gaze behaviours and kinematics of navigation strategies were compared between: 1) athletes specifically trained in navigating in open space versus non-athletes; and 2) athletes with post-concussion syndrome (PCS) versus non-concussed, specifically trained athletes. Specifically trained athletes have been identified as demonstrating more successful perception-action integration in discrete motor tasks related to their sport (Mann et al., 2007; Vickers, 2007). However, whether these abilities translate to the continuous motor task of obstacle avoidance in open space was unknown. The purpose of Study 1 was to identify the influence of sport-specific training on navigating in open space (i.e. navigational strategies of large field sport athletes) compared to age-matched, non-athletes. It was hypothesized that specifically-trained athletes would demonstrate fewer, longer fixations, suggesting a more successful perception-action integration strategy (as defined by Mann et al., 2007), and would employ more sport-specific navigation strategies than non-athletes by maintaining their straight trajectory toward the goal (Fajen & Warren, 2003). Athletes were found to make fewer, longer fixations than non-athletes. However, no differences were observed between navigation strategies of the two groups, nor were any kinematic measures found to differ between groups. It can be concluded that athletes and non-athletes differentially obtain visual information to perform the same actions, suggesting that athletes and non-athletes differentially perform perception-action integration when navigating in open space. Future studies are required to identify sport-specific nuances of navigation (moving obstacles, running) to better identify athletic-related navigation strategies.
Although athletic training can enhance perception-action integration strategies, sport-related injuries can hinder this process. Following a concussion, individuals experience deficits of perception-action integration that persist well beyond 30 days of recovery, post-concussion (Baker and Cinelli, 2014; Slobounov et al., 2006). These perception-action integration deficits may also exist in individual with postconcussion syndrome (PCS). The purpose of the Study 2 was to identify whether perception-action integration deficits persist with the persistent physical symptoms of concussion characteristic of PCS. The current study revealed that athletes with PCS did not differ from non-concussed athletes on any measure of visual fixation strategy, nor were they found to differ on any kinematic measure assessed. These findings suggest that in the context of the current paradigm, athletes with PCS have no perception-action integration deficit. In that, athletes with PCS may have adapted perception-action integration strategies to navigate with equal efficiency as a specifically-trained group of athletes or that the paradigm was not sensitive enough to identify these differences. Such findings suggest that more research is required to assess what, if any, perception-action integration deficits persist with persisting physical symptoms of PCS to better benefit rehabilitative procedures and outcomes for these individuals.
Together, these studies add to what was previously known about perception-action integration, as it relates to navigation. Both studies assessed perception-action integration in unique populations that add to understanding of behavioural dynamics in the sport setting. Study 1 builds on a line of research assessing affordance theory and behavioural dynamics in sport (Fajen, Riley, & Turvey, 2008). The findings of this study suggest that although navigation strategies did not differ between specifically trained athletes and non-athletes, visual search strategies employed in task did. Such findings add to the understanding that sport-specific training influences perception-action integration, through our understanding of how athletes obtain visual information to perform actions. This thesis did not identify perception-action integration deficits in athletes with PCS. These findings suggest that the individuals in the present study likely adapted to their injury as they demonstrated equal ability in gaze and navigation strategies to specifically-trained athletes. As such, further research is required to assess the cognitive, motor, and sensory-motor deficits that may persist with the persisting physical symptoms of PCS. As individuals with PCS do not demonstrate similar visuomotor integration deficits as individuals with acute concussions (Baker & Cinelli, 2014), such individuals must be assessed and researched as a separate population
Aspectos ideológicos de los discursos sobre drogas.
Existen otras maneras de explicar los consumos de drogas, diferentes a la ideología
hegemónica representada por -y en- los discursos oficiales sobre drogas.
Revisaremos algunos aspectos ideológicos en torno a las drogas así como otros postulados
teóricos menos convencionales acerca del uso de drogas: Por una parte, encontramos
autores que narran la historia de los consumos de drogas (ilícitas) como una cuestión
de clase social. Por otro lado, encontramos el enfoque marxista, para el cual el consumo
de drogas favorece el dominio de la ciudadanía [descerebrada] por los órganos de poder.There are other ways of explaining drug consumption, apart from the hegemonic ideology
represented by the official discourse on drugs.
In this text we will review some ideological aspects on drugs and other less conventional
theoretical assumptions about drug use:
On one hand, some authors narrate illicit drug use as a matter of social class. On the
other hand, we find the Marxist approach, in which drug consumption helps the organs
of power to control the [mindless] people
IPv6 Network Mobility
Network Authentication, Authorization, and Accounting has
been used since before the days of the Internet as we know it
today. Authentication asks the question, “Who or what are
you?” Authorization asks, “What are you allowed to do?” And fi nally,
accounting wants to know, “What did you do?” These fundamental
security building blocks are being used in expanded ways today. The
fi rst part of this two-part series focused on the overall concepts of
AAA, the elements involved in AAA communications, and highlevel
approaches to achieving specifi c AAA goals. It was published in
IPJ Volume 10, No. 1[0]. This second part of the series discusses the
protocols involved, specifi c applications of AAA, and considerations
for the future of AAA
Scalable QoS-aware Mobility for Future Mobile Operators
Telecom operators and Internet service providers
are heading for a new shift in communications
paradigms. The forthcoming convergence
of cellular and wireless data networks is often
manifested in an “all IP approach” in which all
communications are based on an end-to-end IP
protocol framework. The approach to network
design becomes user and service-centered, so
that continuous reachability of mobile users and
sustained communication capabilities are default
requirements for a prospective architecture. In
this article, we describe a network architecture
which is able to provide seamless communication
mobility, triggered either by the user or by the
network, across multiple technologies. The architecture
allows for media independent handovers
and supports optimized mobility and resource
management functions. The main focus of the
article is on major technical highlights of mobility
and quality-of-service (QoS) management subsystems
for converged networks.Publicad
Romance and pseudoscience: female indoctrination in hygiene manuals, 1850s-turn of the century
From mid nineteenth century onwards the publication of prescriptive literature for and about women increasingly rose in Spain until reaching its peak by the turn of the century: manuals, essays, treatises and textbooks for girls experienced an unprecedented boom. Hygiene manuals in particular intended to convince women of the need to be guided by male doctors and, while prescribing hygienic practices to improve women's health and that of their families, manuals also prescribed social roles such as that of wife and mother. Thus, the female body and the ways to keep it healthy became a way of preserving Spain's status quo and traditional male authority. The most convincing technique to reinforce that authority was the use of a scientific halo conveyed by medical discourse, with which the authors empowered themselves and their works. However, scientific discourse in hygiene manuals was full of fissures: science was curiously mixed with the popular and the romantic, the literary and ancient beliefs about the female body and mind more in accordance with superstition than scientific objectivity.Desde mediados del siglo diecinueve en adelante la publicación de literatura prescriptiva sobre la mujer y para la mujer aumentó increíblemente en España, alcanzando el máximo número de publicaciones a finales de siglo: la escritura de manuales, ensayos, tratados y libros de texto para niñas vivió un auge sin precedentes. Los manuales de higiene en particular tenían la misión de convencer a la mujer de la necesidad de ser guiada por el médico y, a pesar de prescribir prácticas que servían para mejorar la salud de la mujer y su familia, también prescribían roles sociales tradicionales como el de madre y esposa. De esta forma el cuerpo de la mujer y los métodos para mantenerlo saludable se convirtieron en estrategias para preservar el status quo español y la autoridad masculina. La técnica más convincente para reforzar dicha autoridad fue el uso del discurso médico, que rodeaba con un halo científico a los autores de estos manuales y sus obras, dándoles legitimidad. Sin embargo, el discurso científico en estos manuales de higiene curiosamente estaba lleno de fisuras: se mezclaba la ciencia con el romanticismo y lo popular, lo literario y creencias milenarias referentes al cuerpo y la mente de la mujer que eran más acordes con la superstición que con la objetividad científica
A polynomial Jacobi-Davidson solver with support for non-monomial bases and deflation
[EN] Large-scale polynomial eigenvalue problems can be solved by Krylov methods operating on an equivalent linear eigenproblem (linearization) of size d center dot n where d is the polynomial degree and n is the problem size, or by projection methods that keep the computation in the n-dimensional space. Jacobi-Davidson belongs to the latter class of methods, and, since it is a preconditioned eigensolver, it may be competitive in cases where explicitly computing a matrix factorization is exceedingly expensive. However, a fully fledged implementation of polynomial Jacobi-Davidson has to consider several issues, including deflation to compute more than one eigenpair, use of non-monomial bases for the case of large degree polynomials, and handling of complex eigenvalues when computing in real arithmetic. We discuss these aspects and present computational results of a parallel implementation in the SLEPc library.This work was supported by Agencia Estatal de Investigación (AEI) under Grant TIN2016-75985-P,
which includes European Commission ERDF funds.Campos, C.; Jose E. Roman (2020). A polynomial Jacobi-Davidson solver with support for non-monomial bases and deflation. BIT Numerical Mathematics. 60(2):295-318. https://doi.org/10.1007/s10543-019-00778-zS295318602Bai, Z., Su, Y.: SOAR: a second-order Arnoldi method for the solution of the quadratic eigenvalue problem. SIAM J. Matrix Anal. Appl. 26(3), 640–659 (2005)Balay, S., Abhyankar, S., Adams, M., Brown, J., Brune, P., Buschelman, K., Dalcin, L., Eijkhout, V., Gropp, W., Karpeyev, D., Kaushik, D., Knepley, M., May, D., McInnes, L.C., Mills, R., Munson, T., Rupp, K., Sanan, P., Smith, B., Zampini, S., Zhang, H., Zhang, H.: PETSc users manual. Technical report ANL-95/11—revision 3.10, Argonne National Laboratory (2018)Betcke, T., Kressner, D.: Perturbation, extraction and refinement of invariant pairs for matrix polynomials. Linear Algebra Appl. 435(3), 514–536 (2011)Betcke, T., Voss, H.: A Jacobi–Davidson-type projection method for nonlinear eigenvalue problems. Future Gen. Comput. Syst. 20(3), 363–372 (2004)Betcke, T., Higham, N.J., Mehrmann, V., Schröder, C., Tisseur, F.: NLEVP: a collection of nonlinear eigenvalue problems. ACM Trans. Math. Softw. 39(2), 7:1–7:28 (2013)Campos, C., Roman, J.E.: Parallel Krylov solvers for the polynomial eigenvalue problem in SLEPc. SIAM J. Sci. Comput. 38(5), S385–S411 (2016)Effenberger, C.: Robust successive computation of eigenpairs for nonlinear eigenvalue problems. SIAM J. Matrix Anal. Appl. 34(3), 1231–1256 (2013)Effenberger, C., Kressner, D.: Chebyshev interpolation for nonlinear eigenvalue problems. BIT 52(4), 933–951 (2012)Fokkema, D.R., Sleijpen, G.L.G., van der Vorst, H.A.: Jacobi–Davidson style QR and QZ algorithms for the reduction of matrix pencils. SIAM J. Sci. Comput. 20(1), 94–125 (1998)Guo, J.S., Lin, W.W., Wang, C.S.: Numerical solutions for large sparse quadratic eigenvalue problems. Linear Algebra Appl. 225, 57–89 (1995)Hernandez, V., Roman, J.E., Vidal, V.: SLEPc: a scalable and flexible toolkit for the solution of eigenvalue problems. ACM Trans. Math. Softw. 31(3), 351–362 (2005)Higham, N.J., Al-Mohy, A.H.: Computing matrix functions. Acta Numer. 19, 159–208 (2010)Higham, N.J., Mackey, D.S., Tisseur, F.: The conditioning of linearizations of matrix polynomials. SIAM J. Matrix Anal. Appl. 28(4), 1005–1028 (2006)Hochbruck, M., Lochel, D.: A multilevel Jacobi–Davidson method for polynomial PDE eigenvalue problems arising in plasma physics. SIAM J. Sci. Comput. 32(6), 3151–3169 (2010)Hochstenbach, M.E., Sleijpen, G.L.G.: Harmonic and refined Rayleigh–Ritz for the polynomial eigenvalue problem. Numer. Linear Algebra Appl. 15(1), 35–54 (2008)Huang, T.M., Hwang, F.N., Lai, S.H., Wang, W., Wei, Z.H.: A parallel polynomial Jacobi–Davidson approach for dissipative acoustic eigenvalue problems. Comput. Fluids 45(1), 207–214 (2011)Hwang, F.N., Wei, Z.H., Huang, T.M., Wang, W.: A parallel additive Schwarz preconditioned Jacobi–Davidson algorithm for polynomial eigenvalue problems in quantum dot simulation. J.Comput. Phys. 229(8), 2932–2947 (2010)Kressner, D.: A block Newton method for nonlinear eigenvalue problems. Numer. Math. 114, 355–372 (2009)Kressner, D., Roman, J.E.: Memory-efficient Arnoldi algorithms for linearizations of matrix polynomials in Chebyshev basis. Numer. Linear Algebra Appl. 21(4), 569–588 (2014)Lancaster, P.: Linearization of regular matrix polynomials. Electron. J. Linear Algebra 17, 21–27 (2008)Matsuo, Y., Guo, H., Arbenz, P.: Experiments on a parallel nonlinear Jacobi–Davidson algorithm. Procedia Comput. Sci. 29, 565–575 (2014)Meerbergen, K.: Locking and restarting quadratic eigenvalue solvers. SIAM J. Sci. Comput. 22(5), 1814–1839 (2001)Roman, J.E., Campos, C., Romero, E., Tomas, A.: SLEPc users manual. Technical report DSIC-II/24/02—Revision 3.10, D. Sistemes Informàtics i Computació, Universitat Politècnica de València (2018)Romero, E., Roman, J.E.: A parallel implementation of Davidson methods for large-scale eigenvalue problems in SLEPc. ACM Trans. Math. Softw. 40(2), 13:1–13:29 (2014)Rommes, J., Martins, N.: Computing transfer function dominant poles of large-scale second-order dynamical systems. SIAM J. Sci. Comput. 30(4), 2137–2157 (2008)Saad, Y.: Iterative Methods for Sparse Linear Systems, 2nd edn. SIAM Publications, Philadelphia (2003)Sensiau, C., Nicoud, F., van Gijzen, M., van Leeuwen, J.W.: A comparison of solvers for quadratic eigenvalue problems from combustion. Int. J. Numer. 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NEP: A Module for the Parallel Solution of Nonlinear Eigenvalue Problems in SLEPc
[EN] SLEPc is a parallel library for the solution of various types of large-scale eigenvalue problems. Over the past few years, we have been developing a module within SLEPc, called NEP, that is intended for solving nonlinear eigenvalue problems. These problems can be defined by means of a matrix-valued function that depends nonlinearly on a single scalar parameter. We do not consider the particular case of polynomial eigenvalue problems (which are implemented in a different module in SLEPc) and focus here on rational eigenvalue problems and other general nonlinear eigenproblems involving square roots or any other nonlinear function. The article discusses how the NEP module has been designed to fit the needs of applications and provides a description of the available solvers, including some implementation details such as parallelization. Several test problems coming from real applications are used to evaluate the performance and reliability of the solvers.This work was partially funded by the Spanish Agencia Estatal de Investigacion AEI http://ciencia.gob.es under grants TIN2016-75985-P AEI and PID2019-107379RB-I00 AEI (including European Commission FEDER funds).Campos, C.; Roman, JE. (2021). NEP: A Module for the Parallel Solution of Nonlinear Eigenvalue Problems in SLEPc. ACM Transactions on Mathematical Software. 47(3):1-29. https://doi.org/10.1145/3447544S12947
Finanzas : Propuesta de la administración de inventario de la empresa comercializadora La Compañia,S.A.del periodo enero a noviembre 2017
En el presente trabajo se abordó conceptos y la importancia de la administración de inventario dentro de la empresa comercializadora “La compañía S, A” para el periodo enero a noviembre 2017 al realizar este trabajo obtuvimos información a través de libros y recursos de internet se quiso obtener y profundizar el tema ya que es muy amplio y para mayor comprensión es necesario conocer a fondo todos los conceptos aplicados.
Se utilizó diferente metodología de investigación mediante visitas bibliográficas de libros y páginas web se logró obtener información confiable y segura tanto de la empresa en estudio y temas que relativamente se asocian a la administración de inventario, así mismo se realizó un caso práctico con información real de la empresa comercializadora “La Compañía S, A”.
El caso práctico se realizó atreves del método de control de inventario ABC con este sistema se deduce que lo más conveniente que los materiales que mantienen un mayor volumen en el inventario sean los que menor costo representen del mismo
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