Efficient symbolic computation of approximated small-signal characteristics of analog integrated circuits

A symbolic analysis tool is presented that generates simplified symbolic expressions for the small-signal characteristics of large analog integrated circuits. The expressions are approximated while they are computed, so that only those terms are generated which remain in the final expression. This principle causes drastic savings in CPU time and memory, compared with previous symbolic analysis tools. In this way, the maximum size of circuits that can be analyzed, is largely increased. By taking into account a range for the value of a circuit parameter rather than one single number, the generated expressions are also more generally valid. Mismatch handling is explicitly taken into account in the algorithm. The capabilities of the new tool are illustrated with several experimental result

Symbolic analysis of large analog integrated circuits by approximation during expression generation

A novel algorithm is presented that generates approximate symbolic expressions for small-signal characteristics of large analog integrated circuits. The method is based upon the approximation of an expression while it is being computed. The CPU time and memory requirements are reduced drastically with regard to previous approaches, as only those terms are calculated which will remain in the final expression. As a consequence, the maximum circuit size amenable to symbolic analysis has largely increased. The simplification procedure explicitly takes into account variation ranges of the symbolic parameters to avoid inaccuracies of conventional approaches which use a single value. The new approach is also able to take into account mismatches between the symbolic parameters

A Family of matroid intersection algorithms for the computation of approximated symbolic network functions

In recent years, the technique of simplification during generation has turned out to be very promising for the efficient computation of approximate symbolic network functions for large transistor circuits. In this paper it is shown how symbolic network functions can be simplified during their generation with any well-known symbolic network analysis method. The underlying algorithm for the different techniques is always a matroid intersection algorithm. It is shown that the most efficient technique is the two-graph method. An implementation of the simplification during generation technique with the two-graph method illustrates its benefits for the symbolic analysis of large analog circuits

Algorithm for efficient symbolic analysis of large analogue circuits

An algorithm is presented that generates simplified symbolic expressions for the small-signal characteristics of large analogue circuits. The expressions are approximated while they are computed, so that only the most significant terms are generated which remain in the final expression. This principle leads to dramatic savings in CPU time and memory compared to existing techniques, significantly increasing the maximum size of circuits that can be analysed. By taking into account a range for the value of a circuit parameter rather than one single number the generated symbolic expressions are also generally valid

Análisis de la influencia de la adición de polímeros absorbentes en unidades de albañilería, 2023 – Trujillo

En la ingeniería es muy importante los materiales de construcción, y en los últimos años estos han avanzado a grandes pasos mediante la tecnología que se utiliza para crearlos, y uno de los más utilizados en el mundo de la construcción es el concreto que no ha sido ajeno a este avance tecnológico. La presente tesis, tuvo como objeto principal el “Análisis de la influencia de la adición de polímeros absorbentes en unidades de albañilería”, para esto tuvimos que determinar el grado de influencia en la absorción de agua cal adicionar polímeros absorbentes a las unidades de albañilería, buscar también materiales que mejoren propiedades o una propiedad del concreto, pero a un menor costo comparado con otros aditivos convencionales los cuales sus costos son elevados, y pues, por último ayudar con nuestro trabajo a futuros ingenieros, lectores e investigadores interesados en este tema y reducir la brecha teórica respecto a la inclusión de nuevos elementos en la mezcla de concreto. Finalmente se concluye que a mayor cantidad de adición de polímero en el ladrillo menor será el grado de absorción, puesto que adopta una condición tipo impermeable; asimismo, se concluye que, en comparación de los costos de las unidades de albañilerías convencionales con las unidades de albañilería con adición de polímeros absorbentes, el ladrillo con adición de polímero es más barato que uno convencionalIn engineering, construction materials are very important, and in recent years they have made great strides through the technology used to create them, and one of the most used in the world of construction is concrete that has not been oblivious to this technological advance. The main objective of this thesis was ""Analysis of the influence of the addition of absorbent polymers in masonry units"", for this we had to determine the degree of influence on the absorption of lime water by adding absorbent polymers to masonry units. Also look for materials that improve properties or a property of concrete, but at a lower cost compared to other conventional additives which have high costs, and therefore, finally, help with our work future engineers, readers and researchers interested in this topic and reduce the theoretical gap regarding the inclusion of new elements in the concrete mix. Finally, it is concluded that the greater the amount of polymer addition in the brick, the lower the degree of absorption will be, since it adopts a waterproof type condition; Likewise, it is concluded that, in comparison of the costs of conventional masonry units with masonry units with the addition of absorbent polymers, the brick with polymer addition is cheaper than a conventional one.Tesi

Rediscovery, ecology, and identification of rare free-tailed bats (Chiroptera: Molossidae) in Costa Rica

Five new specimens ofthe poorly known Sanborn's bonneted bat, Eumops hansae (Chiroptera: Molossidae), are reported for Costa Rica's central and northern Pacific lowlands based on a subadult male collected in 1990 and four adult females collected in 2003. We also report the second known specimen of Eumops underwoodi from Costa Rica and additional specimens of Cynomops mexicanus, Eumops glaucinus, Molossus molossus, and Molossus pretiosus. Most of the females captured in August and April were either lactating or pregnant, suggesting that parturition in these molossids occurs in the late dry season and the early to middle rainy season, periods when insects are especially abundant in this dry forest. Characters used previously to distinguish between the similar-sized E. hansae and E. nanus are evaluated, and external and cranial measurements for the specimens of E. hansae are provided. The best single character for distinguishing the two species is size and shape of the upper incisors. In E. hansae, the upper incisors are thin and recurved, whereas they are thick, straight, and slightIy procumbent in E. nanus. The six sympatric species of free-tailed bat found in the gallery forest along the Rio Enmedio vary in size, jaw thickness, and wing shape suggesting coexistence through resource partitioning in this molossid bat assemblage

Monitoring variance by EWMA charts with time varying smoothing parameter

Memory charts like EWMA-S² or CUSUM-S² can be designed to be optimal to detect a specific shift in the process variance. However, this feature could be a serious inconvenience since, for instance, if the charts are designed to detect small shift, then, they can be inefficient to detect moderate or large shifts. In the literature, several alternatives have been proposed to overcome this limitation, like the use of control charts with variable parameters or adaptive control charts. This paper proposes new adaptive EWMA control charts for the dispersion (AEWMA-S²) based on a timevarying smoothing parameter that takes into account the potential misadjustment in the process variance. The obtained control charts can be interpreted as a combination of EWMA control charts designed to be efficient for different shift values. Markov chain procedures are established to analyse and design the proposed charts. Comparisons with other adaptive and traditional control charts show the advantages of the proposals

Gestión integrada de la formación, investigación y extensión universitaria para la adaptación al cambio climático / Management of the Formation, Investigation and University Extension for Adapting to Climatic Change

El articulo presenta las experiencias de La Facultad de Comunicación de la Universidad de La Habana en el apoyo a la adaptación basada en la comunidad a través de la gestión integrada de procesos investigativos, docentes y extensionistas, la gestión de redes de conocimiento e innovación con el entorno y la implementación de estrategias transversales de formación ambiental. Igualmente se hace énfasis en las tendencias investigativas y de ambientalización, la formación de capacidades y la producción. El trabajo puede ser referente tanto para instituciones formativas en el ámbito de la información y la comunicación, como para entidades de apoyo a la adaptación al cambio climático. The article presents the experiences of the Faculty of Communication of the University of Havana in the support of community-based adaptation through the integrated management of research processes, teachers and extensionists, the management of knowledge networks and innovation with the environment and the implementation of cross-cutting environmental training strategies. Emphasis is also placed on research and environmentalization trends, capacity building and production. The work can be a reference both for training institutions in the field of information and communication, and for entities that support adaptation to climate change

EVALUACIÓN DE ELECTROFACIES EN UN YACIMIENTO DE LA FRANJA PETROLERA NORTE CUBANA: Electrofacies evaluation in a deposit of Cuban Oil North Belt

This paper shows the results obtained after applied multivariate statistical classification techniques on geophysical logs in wells located in Cuban Oil North Belt, in Habana del Este field.  The well logs geophysics employed were: natural gamma radioactivity, photoelectric absorption coefficient, total porosity, density, electrical resistivity and caliper. The aim was identifying electrofacies corresponding to seals and reservoirs. The applied procedure integrated the statistical descriptive techniques, main components and  K-means algorithm like unsupervised multivariate statistical classification. It was possible to distinguish four main electrofacies associated with seals and reservoirs. The electrofacies that constitute the seals are related to Vega Alta Formation and are characterized by their high clay content. The electrofacies that represent the collectors are associated with Veloz Group and are made up of sequences with a predominance of carbonates or sandstones, fractured and porous, little clayey. An electrofacies stands out with  organic matter presence, where carbonates predominate and which constitutes the main reservoir. The application of these procedures contributes to reduce oil prospecting risks.Este artículo muestra los resultados obtenidos después de aplicar técnicas de clasificación estadística multivariada sobre registros geofísicos de radiactividad gamma natural, coeficiente de absorción fotoeléctrica, porosidad total, densidad, resistividad eléctrica y caliper en pozos ubicados en el yacimiento Habana del Este, al oeste de la Franja Petrolera Norte Cubana, con el objetivo de identificar electrofacies correspondientes a sellos y reservorios. El procedimiento aplicado integró el análisis estadístico descriptivo, el análisis de componentes principales y la técnica de clasificación estadística multivariada no supervisada K-medias, logrando distinguir cuatro electrofacies principales asociadas a sellos y reservorios. Las electrofacies que constituyen sellos se relacionan con la Formación Vega Alta y se caracterizan por su alta arcillosidad. Las electrofacies que representan los colectores se asocian al Grupo Veloz y están constituidas por secuencias con predominio de carbonatos o de areniscas, poco arcillosas, fracturadas y porosas. Se destaca una electrofacies con presencia de materia orgánica, donde predominan los carbonatos y que constituye el reservorio principal. El desarrollo y aplicación de estos procedimientos contribuye a reducir los riesgos de la prospección petrolera.Este artigo mostra os resultados obtidos após a aplicação de técnicas de classificação estatística multivariada em registros geofísicos de radioatividade gama natural, coeficiente de absorção fotoelétrica, porosidade total, densidade, resistividade elétrica e calibre em poços localizados no campo Habana del Este, a oeste do Faixa Petrolífera do Norte de Cuba, com o objetivo de identificar eletrofácies correspondentes a selos e reservatórios. O procedimento aplicado integrou análise estatística descritiva, análise de componentes principais e a técnica de classificação estatística multivariada não supervisionada K-média, conseguindo distinguir quatro eletrofácies principais associadas a selos e reservatórios. As eletrofácies que constituem os selos estão relacionadas com a Formação Vega Alta e são caracterizadas por sua alta argilosidade. As eletrofácies que representam os coletores estão associadas ao Grupo Veloz e são constituídas por sequências com predominância de carbonatos ou arenitos, pouco argilosos, fraturados e porosos. Destaca-se uma eletrofácies com presença de matéria orgânica, onde predominam os carbonatos e que constitui o reservatório principal. O desenvolvimento e a aplicação desses procedimentos contribuem para reduzir os riscos da prospecção de petróleo