MINLP Model for the Synthesis of Heat Exchanger Networks with Handling Pressure of Process Streams

This paper introduces a new mathematical model for the simultaneous synthesis of heat exchanger networks (HENs), wherein the handling pressure of process streams is used to enhance the heat integration. The proposed approach combines generalized disjunctive programming (GDP) and mixed-integer nonlinear programming (MINLP) formulation, in order to minimize the total annualized cost composed by operational and capital expenses. A multi-stage superstructure is developed for the HEN synthesis, assuming constant heat capacity flow rates and isothermal mixing, and allowing for streams splits. In this model, the pressure and temperature of streams must be treated as optimization variables, increasing further the complexity and difficulty to solve the problem. In addition, the model allows for coupling of compressors and turbines to save energy. A case study is performed to verify the accuracy of the proposed model. In this example, the optimal integration between the heat and work decreases the need for thermal utilities in the HEN design. As a result, the total annualized cost is also reduced due to the decrease in the operational expenses related to the heating and cooling of the streams.

Optimal Design of a Hybrid Membrane System Combining Reverse and Forward Osmosis for Seawater Desalination

In this work we study Forward Osmosis (FO) as an emerging desalination technology, and its capability to replace totally or partially Reverse Osmosis (RO) in order to reduce the great amount of energy required in the current desalination plants. For this purpose, we propose a superstructure that includes both membrane based desalination technologies, allowing the selection of only one of the technologies or a combination of both of them seeking for the optimal configuration of the network. The optimization problem is solved for a seawater desalination plant with a given fresh water production. The results obtained show that the optimal solution combines both desalination technologies to reduce not only the energy consumption but also the total cost of the desalination process in comparison with the same plant but operating only with RO.

Isobutane Alkylation Process Synthesis by means of Hybrid Simulation-Multiobjective Optimization

Multiobjective Generalized Disjunctive Programming (MO-GDP) optimization has been used for the synthesis of an important industrial process, isobutane alkylation. The two objective functions to be simultaneously optimized are the environmental impact, determined by means of LCA (Life Cycle Assessment), and the economic potential of the process. The main reason for including the minimization of the environmental impact in the optimization process is the widespread environmental concern by the general public. For the resolution of the problem we employed a hybrid simulation- optimization methodology, i.e., the superstructure of the process was developed directly in a chemical process simulator connected to a state of the art optimizer. The model was formulated as a GDP and solved using a logic algorithm that avoids the reformulation as MINLP -Mixed Integer Non Linear Programming-. Our research gave us Pareto curves compounded by three different configurations where the LCA has been assessed by two different parameters: global warming potential and ecoindicator-99.

Rigorous design of distillation columns using surrogate models based on Kriging interpolation

The economic design of a distillation column or distillation sequences is a challenging problem that has been addressed by superstructure approaches. However, these methods have not been widely used because they lead to mixed-integer nonlinear programs that are hard to solve, and require complex initialization procedures. In this article, we propose to address this challenging problem by substituting the distillation columns by Kriging-based surrogate models generated via state of the art distillation models. We study different columns with increasing difficulty, and show that it is possible to get accurate Kriging-based surrogate models. The optimization strategy ensures that convergence to a local optimum is guaranteed for numerical noise-free models. For distillation columns (slightly noisy systems), Karush–Kuhn–Tucker optimality conditions cannot be tested directly on the actual model, but still we can guarantee a local minimum in a trust region of the surrogate model that contains the actual local minimum.

Ideological systems and its validation: a neutrosophic approach

Ideologies face two critical problems in the reality, the problem of commitment and the problem of validation. Commitment and validation are two separate phenomena, in spite of the near universal myth that the human is committed because his beliefs are valid. Ideologies not only seem external and valid but also worth whatever discomforts believing entails. In this paper the authors develop a theory of social commitment and social validation using concepts of validation of neutrosophic logic.

Retrofit of heat exchanger networks with pressure recovery of process streams at sub-ambient conditions

This paper presents a new mathematical programming model for the retrofit of heat exchanger networks (HENs), wherein the pressure recovery of process streams is conducted to enhance heat integration. Particularly applied to cryogenic processes, HENs retrofit with combined heat and work integration is mainly aimed at reducing the use of expensive cold services. The proposed multi-stage superstructure allows the increment of the existing heat transfer area, as well as the use of new equipment for both heat exchange and pressure manipulation. The pressure recovery of streams is carried out simultaneously with the HEN design, such that the process conditions (streams pressure and temperature) are variables of optimization. The mathematical model is formulated using generalized disjunctive programming (GDP) and is optimized via mixed-integer nonlinear programming (MINLP), through the minimization of the retrofit total annualized cost, considering the turbine and compressor coupling with a helper motor. Three case studies are performed to assess the accuracy of the developed approach, including a real industrial example related to liquefied natural gas (LNG) production. The results show that the pressure recovery of streams is efficient for energy savings and, consequently, for decreasing the HEN retrofit total cost especially in sub-ambient processes.

Optimization of Chemical Processes Using Surrogate Models Based on a Kriging Interpolation

Superstructure approaches are the solution to the difficult problem which involves the rigorous economic design of a distillation column. These methods require complex initialization procedures and they are hard to solve. For this reason, these methods have not been extensively used. In this work, we present a methodology for the rigorous optimization of chemical processes implemented on a commercial simulator using surrogate models based on a kriging interpolation. Several examples were studied, but in this paper, we perform the optimization of a superstructure for a non-sharp separation to show the efficiency and effectiveness of the method. Noteworthy that it is possible to get surrogate models accurate enough with up to seven degrees of freedom.

Constituição e modelo de mercado : uso liberal e desuso neoliberal

Tese de doutoramento, Direito (Ciências Jurídico-Políticas), Universidade de Lisboa, Faculdade de Direito, 2016

Althusser lector de Gramsci

Este trabajo examina las lecturas de Gramsci realizadas por Althusser, desde sus primeras notas críticas y anotaciones hasta sus escritos sobre la ;crisis del marxismo. Subraya la profunda ambivalencia de las interpretaciones de Althusser. Por una parte, Gramsci es presentado como un precursor, como la única figura dentro de la tradición marxista que intentó pensar la superestructura y en particular lo político. Por otra parte, el corpus gramsciano es criticado como la instancia paradigmática de un concepto de la temporalidad y de la política con el que Althusser disiente. Considerando la crítica althusseriana, identificamos dos fases distintas, comenzando por una crítica al desconocimiento del status específico de la ciencia en general, y en particular de la ciencia de la historia, que caracteriza al período de la segunda mitad de los sesentas, Althusser formuló, hacia el final de los setentas, una crítica del concepto gramsciano de hegemonía que, en su opinión, borra el ;problema de la dominación de clase

Althusser lector de Gramsci

Este trabajo examina las lecturas de Gramsci realizadas por Althusser, desde sus primeras notas críticas y anotaciones hasta sus escritos sobre la ;crisis del marxismo. Subraya la profunda ambivalencia de las interpretaciones de Althusser. Por una parte, Gramsci es presentado como un precursor, como la única figura dentro de la tradición marxista que intentó pensar la superestructura y en particular lo político. Por otra parte, el corpus gramsciano es criticado como la instancia paradigmática de un concepto de la temporalidad y de la política con el que Althusser disiente. Considerando la crítica althusseriana, identificamos dos fases distintas, comenzando por una crítica al desconocimiento del status específico de la ciencia en general, y en particular de la ciencia de la historia, que caracteriza al período de la segunda mitad de los sesentas, Althusser formuló, hacia el final de los setentas, una crítica del concepto gramsciano de hegemonía que, en su opinión, borra el ;problema de la dominación de clase

Illustrated technical dictionary in six languages, English, German, French, Russian, Italian, Spanish /

Vols. 7-13 have added t.p.: Schlomann-Oldenbourgh illustrierte technische wörterbücher, unter mitwirkung hervorragender fachieute des in- und auslandes, hrsg. von Alfred Schlomann ... Müchen und Berlin, Druck und verlag von R. Oldenbourg; London, Constable & Co., etc.

Althusser lector de Gramsci

Este trabajo examina las lecturas de Gramsci realizadas por Althusser, desde sus primeras notas críticas y anotaciones hasta sus escritos sobre la ;crisis del marxismo. Subraya la profunda ambivalencia de las interpretaciones de Althusser. Por una parte, Gramsci es presentado como un precursor, como la única figura dentro de la tradición marxista que intentó pensar la superestructura y en particular lo político. Por otra parte, el corpus gramsciano es criticado como la instancia paradigmática de un concepto de la temporalidad y de la política con el que Althusser disiente. Considerando la crítica althusseriana, identificamos dos fases distintas, comenzando por una crítica al desconocimiento del status específico de la ciencia en general, y en particular de la ciencia de la historia, que caracteriza al período de la segunda mitad de los sesentas, Althusser formuló, hacia el final de los setentas, una crítica del concepto gramsciano de hegemonía que, en su opinión, borra el ;problema de la dominación de clase

ENSINO SUPERIOR E FORMAÇÃO HUMANA: A PERSPECTIVA DE PROFESSORES DO CURSO DE PEDAGOGIA

A finalidade deste trabalho é discutir formação no ensino superior e o que significa formação humana para professores do curso de pedagogia. Considerando a complexidade do tema, a intenção desta pesquisa é apontar os modos pelos quais certas metas oficiais do ensino superior, consagradas na legislação vigente, repercutem na consciência dos professores. Realizou-se uma pesquisa bibliográfica com o objetivo de apurar como o ideal da formação humana se inscreveu historicamente no mundo universitário e no sistema de ensino superior. Posteriormente foi desenvolvida uma pesquisa empírica. Para a coleta de dados, foram realizadas entrevistas seguindo um roteiro. Após a coleta dos dados, foi feita uma análise qualitativa individual de cada entrevista destacando pontos relevantes. Foi realizada uma análise geral com a junção de opiniões convergentes, pois embora os discursos tenham se mostrado diferentes, identificamos tendências de pensamento sobre os temas. Referindo-nos às opiniões dos autores apresentados que sinalizam para uma estruturação do ensino superior voltada a formar pessoas capazes de atender ao mercado de trabalho, e às opiniões dos professores entrevistados nesta pesquisa, podemos entender que a formação humana no ensino superior é uma ideologia. Ela existe no discurso oficial e na documentação legal, mas na prática não se concretiza. A diversidade das opiniões apuradas evidencia que os dispositivos legais referentes ao ensino superior criaram uma superestrutura ideológica flexível cujas fórmulas são suscetíveis de serem apreendidas de modo diferenciado nos agentes do sistema do ensino superior e são pouco operacionalizadas nas atuais estruturas deste sistema.(AU)

Meeting the challenge on the path to democracy: discursive strategies in governmental declarations

The communicative practice in the ex-GDR was complex and diverse, although public political discourse had been fairly ritualized. Text-types characteristic of the Communist Party discourse were full of general (superordinate) terms semantic specification was hardly possible (propositional reduction). Changes in the social world result in changes in the communicative practice as well. However, a systematic comparision of text-types across cultures and across ideological boundaries reveals both differences in the textual macro- and superstructures and overlapping as well as universal features, probably related to functional aspects (discourse of power). Six sample texts of the text-type `government declaration', two produced in the ex-GDR, four in the united Germany, are analysed. Special attention is paid to similarities and differences (i) in the textual superstructure (problem-solution schema), (ii) in the concepts that reflect the aims of political actions (simple worlds), (iii) in the agents who (are to) perform these actions (concrete vs abstract agents). Similarities are found mainly in the discursive strategies, e.g. legitimization text actions. Differences become obvious in the strategies used for legitimization, and also in the conceptual domains referred to by the problem-solution schema. The metaphors of construction, path and challenge are of particular interest in this respect.

Characterizing femtosecond laser inscribed Bragg grating spectra

We present numerical modeling based on a combination of the Bidirectional Beam Propagation Method and Finite Element Method that completely describes the wavelength spectra of point by point femtosecond laser inscribed fiber Bragg gratings, showing excellent agreement with experiment. We have investigated the dependence of different spectral parameters such as insertion loss, all dominant cladding and ghost modes and their shape relative to the position of the fiber Bragg grating in the core of the fiber. Our model is validated by comparing model predictions with experimental data and allows for predictive modeling of the gratings. We expand our analysis to more complicated structures, where we introduce symmetry breaking; this highlights the importance of centered gratings and how maintaining symmetry contributes to the overall spectral quality of the inscribed Bragg gratings. Finally, the numerical modeling is applied to superstructure gratings and a comparison with experimental results reveals a capability for dealing with complex grating structures that can be designed with particular wavelength characteristics. (C) 2010 Optical Society of America