Partition games

We introduce CUT, the class of 2-player partition games. These are NIM type games, played on a finite number of heaps of beans. The rules are given by a set of positive integers, which specifies the number of allowed splits a player can perform on a single heap. In normal play, the player with the last move wins, and the famous Sprague-Grundy theory provides a solution. We prove that several rulesets have a periodic or an arithmetic periodic Sprague-Grundy sequence (i.e. they can be partitioned into a finite number of arithmetic progressions of the same common difference). This is achieved directly for some infinite classes of games, and moreover we develop a computational testing condition, demonstrated to solve a variety of additional games. Similar results have previously appeared for various classes of games of take-and-break, for example octal and hexadecimal; see e.g. Winning Ways by Berlekamp, Conway and Guy (1982). In this context, our contribution consists of a systematic study of the subclass `break-without-take'

Sol–gel synthesis and characterization of barium (magnesium) aluminosilicate glass sealants for solid oxide fuel cells

Solid oxide fuel cells (SOFC) correspond to efficient energy conversion systems coupled with low emissions of pollutants. In the aim to fabricate high temperature planar SOFC, glass and glass-ceramic sealants are developed to associate several criteria and properties : high thermal expansion (11.0 to 12.0 ⋅ 10− 6 K− 1), high electrical resistance > 2 kΩ/cm2, good thermochemical compatibility with the other active materials of the fuel cell, and stability under H2 and H2O atmospheres at an operation temperature of 800 °C for a long time. According to these requirements, new BAS (BaO–Al2O3–SiO2) and BMAS (BaO–MgO–Al2O3–SiO2) glass-ceramic sealants have been developed by sol–gel route which is a non-conventional process for such applications. By this soft chemistry process, we anticipate a decrease in the glasses processing temperature due to a better homogeneity between cationic precursors in the mixture and a more important reactivity of materials. Experimental results in terms of thermomechanical properties, thermal expansion coefficient, crystalline phase content, and microstructure were discussed. In particular, the influence of the %BaO on the thermomechanical properties of glass-ceramics was described. Changes in properties of glass-ceramics were closely related to the microstructure. The influence of MgO on glass processing temperatures, on the structure and on the microstructure is evaluated in order to confirm that these glass-ceramics are promising candidates to SOFC applications. So, after performing a systematic investigation to the various systems, the properties of suitable glass were proposed

Benchmarking solid oxide electrolysis cell-stacks for industrial Power-to-Methane systems via hierarchical multi-scale modelling

Power-to-Gas (PtG) is prognosticated to realize large capacity increases and create substantial revenues within the next decade. Due to their inherently high efficiencies, solid oxide electrolysis cells (SOECs) have the potential to become one of the core technologies in PtG applications. While thermal integration of the high-temperature SOEC module with downstream exothermic methanation is a very potent concept, the performance of SOECs needs to be boosted to amplify the technologies impact for future large-scale plants. Here, we use a combined experimental and modelling approach to benchmark commercial electrolyte- (ESC) and cathode-supported cell (CSC) designs on industrial-scale planar SOEC stack performance. In a first step, comprehensive electrochemical and microstructural analyses are carried out to parametrize, calibrate and validate a detailed multi-physics 2D cell model, which is then used to study the cells’ behaviour in detail. The analysis reveals that there exists a cell-specific threshold steam conversion of ∼80% for the ESC and ∼75% for the CSC design, which represents a maximum of the total (heat plus electrical) electrolysis efficiency. Moreover, while the ESC-design suffers from performance reductions under pressurized conditions, considerable performance increases of ∼9% at 20 atm (700 °C, 1.35 V) compared to atmospheric pressure are predicted for the CSC design, showcasing a unique advantage of the CSC cell for process integration with the catalytic methanation. Subsequently, based on a 3D stack model, a scale-up to the industrial stack size is conducted. To comparatively assess stack performances under application-oriented conditions, optimization studies are carried out for 150-cell stack units based on the two cell designs individually. When optimally selecting the stack operation points, the model predicts the CSC-based stack to reach a high capacity up to 36.6 kW (∼10.6 Nm$^3$ H$_2$ h$^{−1}$) at 1.35 V and 700 °C, whilst ensuring reasonably low temperature gradients (<10 K cm$^{−1}$) and sweep gas cooling requirements (<30 sccm cm$^{−2}$). Thus, CSC-design stacks incorporating such a highly active cell design can be expected to further boost the competitiveness of high-temperature electrolysis in PtG plant concepts

Influencia de agregado reciclado de construcción para estabilización de suelos arcillosos en el distrito de Sitabamba, Santiago de Chuco, 2022

La presente investigación tuvo por objetivo determinar la influencia de agregados reciclados de demolición de construcciones existentes, en este caso, concreto y ladrillo, para la estabilización de suelos arcillosos en el distrito de Sitabamba, Santiago de Chuco, 2022. Esta investigación según su propósito es aplicada, el diseño de esta investigación es experimental de tipo pre experimental. La población fue el suelo arcilloso de la vía Panubamba – San Sebastián. La muestra fue determinada por la técnica no probabilística, por conveniencia. De los resultados, se logró demostrar que los agregados reciclados de construcción mejoran la estabilización de suelos de la vía Panubamba – San Sebastián, Distrito de Sitabamba, Santiago de Chuco, reduciendo en 35.74% el índice de plasticidad de 10.94% a 7.03%. Respecto a la máxima densidad seca, esta se incrementó de 1.87 gr/cm3 a 1.98 gr/cm3, la humedad optima se incrementó de 8.38% a 9.11%. Con respecto a la capacidad portante soporte CBR se incrementó de 35% a 43%, ubicándola con este valor en el rango adecuado para conformar la capa de subbase, según MTC siendo el valor mínimo aceptable el de 40%. Se concluyó que, las características geotécnicas del suelo encontradas en la vía Panubamba – San Sebastián, Distrito de Sitabamba, Santiago de Chuco tienen un índice de plasticidad de 10.94, una máxima densidad seca de 1.87 gr/cm3,una humedad óptima de 8.36% y con un valor de capacidad portante soporte CBR de 35%, presentando una clasificación SUCS SC y AASHTO: A-2-6(0), las mismas que requieren de mejora, lo cual se logra con un suelo natural con adición del 5% de agregados reciclados de construcción demolida

La biomecánica postural en el proceso de aprendizaje de instrumentos musicales de los estudiantes de la especialidad de Música de la Universidad Nacional de Educación Enrique Guzmán y Valle

El objetivo principal de la investigación fue determinar la incidencia de la biomecánica postural en el proceso de aprendizaje de instrumentos musicales en los estudiantes de la especialidad de música en la Universidad Nacional de Educación Enrique Guzmán y Valle.El estudio por la naturaleza tuvo un enfoque de tipo cuantitativo, fue de tipo básica, con un diseño no experimental de nivel descriptivo correlacional de corte transversal. La población estuvo setenta (70) estudiantes de la especialidad de música de la Universidad Nacional de Educación Enrique Guzmán y Valle. La técnica utilizada fue la encuesta, los instrumentos que permitieron recabar la información respectiva fueron: Cuestionario sobre biomecánica postural y cuestionario sobre el aprendizaje de instrumentos musicales. Los resultados arrojaron lo siguiente: existe correlación significativa total entre la biomecánica postural y el aprendizaje de instrumentos musicales en los estudiantes de la especialidad de música de la Universidad Nacional de Educación Enrique Guzmán y Valle.The main objective of the research was to determine the incidence of postural biomechanics in the musical instrument learning process in students of the music specialty at the Enrique Guzmán y Valle National University of Education. The study by nature had a quantitative approach, it was of a basic type, with a non-experimental design of cross- sectional correlational descriptive level. The population was seventy (70) students of the specialty of music of the National University of Education Enrique Guzmán y Valle. The technique used was the survey, the instruments that made it possible to collect the respective information were: Questionnaire on postural biomechanics and questionnaire on learning musical instruments. The results showed the following: there is a total significant correlation between postural biomechanics and the learning of musical instruments in the students of the music specialty of the Enrique Guzmán y Valle National University of Education

Complexity and Algorithms for ISOMETRIC PATH COVER on Chordal Graphs and Beyond

A path is isometric if it is a shortest path between its endpoints. In this article, we consider the graph covering problem Isometric Path Cover, where we want to cover all the vertices of the graph using a minimum-size set of isometric paths. Although this problem has been considered from a structural point of view (in particular, regarding applications to pursuit-evasion games), it is little studied from the algorithmic perspective. We consider Isometric Path Cover on chordal graphs, and show that the problem is NP-hard for this class. On the positive side, for chordal graphs, we design a 4-approximation algorithm and an FPT algorithm for the parameter solution size. The approximation algorithm is based on a reduction to the classic path covering problem on a suitable directed acyclic graph obtained from a breadth first search traversal of the graph. The approximation ratio of our algorithm is 3 for interval graphs and 2 for proper interval graphs. Moreover, we extend the analysis of our approximation algorithm to k-chordal graphs (graphs whose induced cycles have length at most k) by showing that it has an approximation ratio of k+7 for such graphs, and to graphs of treelength at most ?, where the approximation ratio is at most 6?+2

Social Anthropology Dissertation Photographs 2017

A collection of photographs submitted to the Social Anthropology Undergraduate Dissertation Photo Competition 2017 complete with short reflections and commentary from authors