Inventory management based on simulation of ordering process

Inventory management is one of the key operational functions of a company which, in the context of modern Supply Chain Management schemes, plays an important role both for the company itself and the coordination with the SC partners. Especially the aspect of service level and stockout probability has become critical. Classical methods of inventory management are based on simple analytical formulae which, however, only treat special cases. In this contribution we present a tool for the optimization of inventory management which is based on a simulation of the ordering processes. The full stochastic properties of the ordering process are incorporated which allows an accurate determination of performance measures like service level. With this tool, the determination of cost-minimal inventory parameters (reorder level, reorder quantity) for given stockout probability is easily possible

Soft masses in superstring models with anomalous U(1) symmetries

We analyze the general structure of soft scalar masses emerging in superstring models involving anomalous U(1) symmetries, with the aim of characterizing more systematically the circumstances under which they can happen to be flavor universal. We consider both heterotic orbifold and intersecting brane models, possibly with several anomalous and non-anomalous spontaneously broken U(1) symmetries. The hidden sector is assumed to consist of the universal dilaton, Kahler class and complex structure moduli, which are supposed to break supersymmetry, and a minimal set of Higgs fields which compensate the Fayet-Iliopoulos terms. We leave the superpotential that is supposed to stabilize the hidden sector fields unspecified, but we carefully take into account the relations implied by gauge invariance and the constraints required for the existence of a metastable vacuum with vanishing cosmological constant. The results are parametrized in terms of a constrained Goldstino direction, suitably defined effective modular weights, and the U(1) charges and shifts. We show that the effect induced by vector multiplets strongly depends on the functional form of the Kahler potential for the Higgs fields. We find in particular that whenever these are charged matter fields, like in heterotic models, the effect is non-trivial, whereas when they are shifting moduli fields, like in certain intersecting brane models, the effect may vanish.Comment: 35 pages, LaTe

Kundenfreundliche und robuste Ersatzfahrpläne während Bau- und Unterhaltsintervallen

An der ZHAW wurde ein Verfahren entwickelt, um in kürzester Zeit Ersatzfahrpläne für Bau- und Unterhaltsintervalle zu erstellen – ein für den stabilen Bahnbetrieb zunehmend wichtiges Thema. Die Methode berücksichtigt nicht nur betriebliche Aspekte wie die temporären Einschränkungen der Bahnanlage, sondern stellt gleichzeitig auch den Kundennutzen ins Zentrum der Planung. Dadurch kann das beste Transportangebot in Bezug auf Reisezeiten und Zuverlässigkeit realisiert werden

Factores clave en los mercados de acceso móvil a contenidos

El propósito de este artículo es la identificación y análisis de los factores (técnicos, económicos, sociales y normativos) que, en la actualidad, y también lo harán en el medio plazo, están contribuyendo o impidiendo el desarrollo de los mercados de acceso a contenidos por medio de redes móviles. Este repaso sirve para establecer un marco general en que encuadrar posteriores investigaciones y, a la vez, hace posible sugerir qué medidas serían convenientes para orientar la futura evolución del sector. The main goal of the analysis summarized in this paper is to identify essential economic, technological, social and legal forces that are currently shaping (and will shape, in the short and middle-term) the mobile content sector. To illustrate the nature of their impact should inform subsequent research and provide policy-makers with a coherent and comprehensive picture of the sector¿s current state and future evolution.JRC.J.3-Information Societ

Constraints for the existence of flat and stable non-supersymmetric vacua in supergravity

We further develop on the study of the conditions for the existence of locally stable non-supersymmetric vacua with vanishing cosmological constant in supergravity models involving only chiral superfields. Starting from the two necessary conditions for flatness and stability derived in a previous paper (which involve the Kahler metric and its Riemann tensor contracted with the supersymmetry breaking auxiliary fields) we show that the implications of these constraints can be worked out exactly not only for factorizable scalar manifolds, but also for symmetric coset manifolds. In both cases, the conditions imply a strong restriction on the Kahler geometry and constrain the vector of auxiliary fields defining the Goldstino direction to lie in a certain cone. We then apply these results to the various homogeneous coset manifolds spanned by the moduli and untwisted matter fields arising in string compactifications, and discuss their implications. Finally, we also discuss what can be said for completely arbitrary scalar manifolds, and derive in this more general case some explicit but weaker restrictions on the Kahler geometry.Comment: 22 pages, Latex, no figure

Compact solution of circular orbit relative motion in curvilinear coordinates

A compact approximate solution of the highly non-linear relative motion in curvilinear coordinates is provided under the assumption of circular orbit for the chief spacecraft and moderately small inclination and eccentricity for the follower. The rather compact three-dimensional solution, which employs time as independent variable, is obtained by algebraic manipulation of the individual Keplerian motions in curviinear coordinates and Taylor expansion for small eccentricity of the follower orbit. Numerical test cases are conducted to show that the approximate solution can be effectively employed to extend the classical linear Clohessy-Wiltshire solution to include non-linear relative motion without significant loss of accuracy up to a limit of 0.4-0.5 in eccentricity and a few degrees in inclination

Factores que inciden en la aplicacion y desarrollo de los ejes articuladores de la Reforma Educacional al interior de los Centros Educativos

120 p.Este estudio, esta dirigido a establecer las percepciones de los docentes acerca de los diversos componentes de la Reforma Educacional y algunos factores de la cultura organizacional considerados relevantes por los educadores, y que comúnmente, no son incorporados como variables en los trabajos de investigación publicados sobre el tema. Los factores explicativos asociados a este fenómeno, atraviesan por una serie de aspectos que van, desde las criticas veladas a las acciones emprendidas por el Ministerio de Educación, hasta la creencia de la falta de competencias profesionales de los educadores. En el estudio se constata la influencia de elementos de la cultura organizacional referidos a las relaciones interpersonales de los docentes, que actúan como catalizadores en el proceso de implementación de las políticas educacionales. Del análisis de los resultados, se determinan aspectos a los cuales se les debe asignar prioridad en la gestión y en la generación de nuevos estilos de convivencia, con el propósito de lograr un mejoramiento sustantivo en el ámbito curricular

Efecto de distintos mulchings sobre la humedad y temperatura del suelo, estado hídrico, incidencia de malezas y crecimiento de un cultivo en implantación de mandarina Nova en Concordia, Entre Ríos

Tesis para optar por el grado académico de Magister Scientiae en Cultivos Intensivos, de la Universidad Nacional del Litoral, en 2015La eliminación de la cobertura vegetal en plantaciones citrícolas de Concordia (Entre Ríos) por diferentes prácticas de manejo contribuye a la degradación de las propiedades físicas, químicas y biológicas del suelo. El objetivo de este trabajo fue evaluar el efecto de distintos mulchings sobre la humedad y temperatura del suelo, el estado hídrico del cultivo, la incidencia de malezas y crecimiento de un cultivo de mandarina Nova. La experiencia se realizó en las campañas 2012/2013 y 2013/2014. Los tratamientos fueron: testigo; manejo químico convencional; mulching de cáscara de arroz 6 y 12 centímetros de espesor; mulching de chip de madera de eucalipto de 6 y 12 centímetros de espesor; cobertura plástica de 250 micrones. Durante la primavera y el verano los mulchings incrementaron entre 16 y 96% la humedad volumétrica del suelo (10 centímetros), correspondiendo los mayores aumentos a las coberturas de chip de eucalipto. Los mulchings orgánicos disminuyeron la temperatura del suelo hasta los 15 centímetros de profundidad, logrando las menores temperaturas superficiales (0-5 centímetros), mientras que la cobertura plástica tuvo valores intermedios entre el manejo químico convencional y las coberturas orgánicas. En períodos de déficit hídrico el potencial hídrico del tallo fue superior bajo los mulchings de chip de eucalipto y cáscara de arroz de 12 centímetros de espesor. Los mulchings de chip de eucalipto y la cobertura plástica brindaron los mejores controles de malezas. Las coberturas evaluadas permitieron incrementos en el crecimiento del diámetro del tronco y la copa de los árboles del 29 y 47% respectivamente.The practice of eliminating the vegetal cover of citrus orchards in Concordia (Entre Ríos) contributes to the degradation of the physical, chemical, and biological properties of the soil. The objective of this study was to evaluate the effects of utilizing different mulches on soil moisture and temperature, water status of the crop, incidence of weeds, and growth of a Nova mandarin orchard. This experiment was conducted in campaigns 2012/2013 and 2013/2014. The seven experimental treatments were: control; conventional chemical management; 6 and 12 centimeters thick rice husk mulch; 6 and 12 centimeters thick eucalyptus wood chip mulch; and plastic cover mulch of 250 microns thick. During spring and summer, the volumetric moisture of the soil increased between 16 and 96% with the use of the mulches (approximately 10 centimeters), with the largest increases observed in soil with eucalyptus wood chip mulches. The organic mulches decreased soil temperature up to a depth of 15 centimeters, achieving the lowest surface temperatures (0-5 centimeters), whereas the plastic cover mulch had temperatures values in between those of the conventional chemical management and the organic mulches. In periods of water deficit, the stem water potential was higher for the eucalyptus wood chip mulches and the rice husk mulch of 12 centimeters thick. The eucalyptus wood chip mulches and the plastic cover showed the best weed control. Additionally, the evaluated mulches increased the growth of stem and treetop diameters by 29 and 47% respectively.EEA ConcordiaFil: Gomez, Claudio Andres. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Concordia; Argentin

Development of a prototype for the automated generation of timetable scenarios specified by the transport service intention

Within the next 5 to 10 years, public transport in Switzerland as well as in other European countries will experience major technological and organisational changes. However, changes will also take place on the customer side, resulting in different mobility behaviour and demand patterns. These changes will lead to additional challenges for transport service providers in private as well as public domains. Time to market will be a key success factor and it is unnecessary to mention that due to these factors the speed and flexibility of business processes in freight as well as in passenger transport industry have to be increased significantly. Within the railway value chain (line planning, timetabling and vehicle scheduling etc.) the coordination of the individual planning steps is a key success factor. SBB as the leading service provider in public transport in Switzerland has recognized this challenge and, together with various partners, initiated the strategic project Smart Rail 4.0. The ZHAW and especially the Institute for Data Analysis and Process Design (IDP) of the School of Engineering wants to be part of this transformation process and to contribute with research and educational activities. The IDP research therefore aims for the transformation of academic and scientific know-how to practical applicability. In a first step this concerns directly the current Smart Rail 4.0 TMS-PAS project activities, that concentrate on timetabling issues. The IDP project team considers the integration of the line planning and the timetabling process as crucial for practical applications. To address this in the current research project, we present an application concept that enables the integration of these two major process steps in the transport service value-chain. Although it turns out from our research, that the technical requirements for the integration of the process can be satisfied, rules and conditions for a closer cooperation of the involved business units, the train operating companies and the infrastructure operating company, have to be improved and to be worked out in more detail. In addition to a detailed application concept with use cases for the timetabling process we propose a methodology for computer aided timetable generation based on the central planning object known as ‘service intention’. The service intention can be used to iteratively develop the timetable relying on a ‘progressive feasibility assessment’, a feature that is requested in practice. Our proposed model is based on the ‘track-choice’ and line rotation extension of the commonly known method for the generation of periodic event schedules ‘PESP’. The extension makes use of the track infrastructure representation which is also used in the line planning and timetabling system Viriato. This system that is widely used by public transport planners and operators. With the help of Viriato, it is rather easy to configure the timetabling problem in sufficient detail. On the other side, the level of detail of the considered data is light enough to algorithmically solve practical timetabling problems of realistic sizes. Taking into consideration the technical and operational constraints given by rolling stock, station and track topology data on one hand, and the commercial requirements defined by a given line concept on the other, the method presented generates periodic timetables including train-track assignments. In the first step, the standardized data structure ‘service intention’ represents the line concept consisting of train paths and frequencies. Due to the utilization of infrastructure-based track capacities, we are also able to assess the feasibility of the line concept given. Additionally, the method allows for handling temporary resource restrictions (e.g. caused by construction sites or operational disturbances). In order to assess the performance of the resulting timetable we present a framework for performance measurement that addresses the customer convenience (in terms of start-to-end travel time) as well as operational stability requirements (in terms of delay sensitivity and critical relations)