Rapid sizing tool for a low cost university microsatellite structure subsystem

In recent decays university class small satellites are creating many opportunities for space research and professional trainings while at the same time responding to constrained budgets. In this work the main focus is on developing a simple and rapid structural sizing tool considering the main objectives of a low cost university class microsatellite project. In satellite projects, structure subsystem is one of the influential subsystems as a driver of the cost and acceptance of the final design. At the first steps of such projects there is no confirmed data regarding the launch vehicle or even in some cases there is no data for the satellite payload. Due to these facts, developing simple sizing tools at conceptual design phase for obtaining an over view of the effect of different variables is useful before entering complex calculations in detailed design phases. In this study, after developing a simple analytical model of satellite structure subsystem, a design space is evaluated with practical boundaries considering mass and dimensions constraints of such projects. The results are useful to give initial insight to establish the system level structural sizing

Multiobjective optimization applied to structural sizing of low cost university-class microsatellite projects

In recent years, there has been continuing interest in the participation of university research groups in space technology studies by means of their own microsatellites. The involvement in such projects has some inherent challenges, such as limited budget and facilities. Also, due to the fact that the main objective of these projects is for educational purposes, usually there are uncertainties regarding their in orbit mission and scientific payloads at the early phases of the project. On the other hand, there are predetermined limitations for their mass and volume budgets owing to the fact that most of them are launched as an auxiliary payload in which the launch cost is reduced considerably. The satellite structure subsystem is the one which is most affected by the launcher constraints. This can affect different aspects, including dimensions, strength and frequency requirements. In this paper, the main focus is on developing a structural design sizing tool containing not only the primary structures properties as variables but also the system level variables such as payload mass budget and satellite total mass and dimensions. This approach enables the design team to obtain better insight into the design in an extended design envelope. The structural design sizing tool is based on analytical structural design formulas and appropriate assumptions including both static and dynamic models of the satellite. Finally, a Genetic Algorithm (GA) multiobjective optimization is applied to the design space. The result is a Pareto-optimal based on two objectives, minimum satellite total mass and maximum payload mass budget, which gives a useful insight to the design team at the early phases of the design.

Optimum sizing of bare-tape tethers for de-orbiting satellites at end of mission

De-orbiting satellites at end of mission would prevent generation of new space debris. A proposed de-orbit technology involves a bare conductive tape-tether, which uses neither propellant nor power supply while generating power for on-board use during de-orbiting. The present work shows how to select tape dimensions for a generic mission so as to satisfy requirements of very small tether-to-satellite mass ratio mt/MS and probability Nf of tether cut by small debris, while keeping de-orbit time tf short and product tf ×× tether length low to reduce maneuvers in avoiding collisions with large debris. Design is here discussed for particular missions (initial orbit of 720 km altitude and 63° and 92° inclinations, and 3 disparate MS values, 37.5, 375, and 3750 kg), proving it scalable. At mid-inclination and a mass-ratio of a few percent, de-orbit time takes about 2 weeks and Nf is a small fraction of 1%, with tape dimensions ranging from 1 to 6 cm, 10 to 54 μμm, and 2.8 to 8.6 km. Performance drop from middle to high inclination proved moderate: if allowing for twice as large mt/MS, increases are reduced to a factor of 4 in tf and a slight one in Nf, except for multi-ton satellites, somewhat more requiring because efficient orbital-motion-limited electron collection restricts tape-width values, resulting in tape length (slightly) increasing too.

Rapid method for spacecraft sizing

In this paper, a rapid method for spacecraft sizing is presented. This method is useful in both the conceptual and preliminary design phases of scientific and communication satellites. The aim of this method is to provide a sizing procedure similar to the ones used in the design of aircraft; actually by determining the mass of all the spacecraft subsystems. In the Introduction, the importance of an accurate initial mass budget in the design of satellites is emphasized. Literature about this topic is not very extensive and most of the existing methods have been recapitulated. The methodology followed in the proposed procedure for spacecraft mass sizing is based on these methods. Data from 26 existing satellites have been considered to obtain correlations between each subsystem mass and the mass of the whole spacecraft.

Estudio experimental del Sistema de Albañilería Integral en la construcción de viviendas sismorresistentes. Experimental study of the Integral Masonry System in the construction of earthquake resistant houses

This paper presents the application of the Integral Masonry System (IMS) to the construction of earthquake resistant houses and its experimental study. To verify the security of this new type of building in seismic areas of the third world two prototypes have been tested, one with adobe and the other with hollow brick. In both cases it’s a two-story 6x6x6 m3 house built to scale 1/2. The tests are carried out at the Laboratory of Antiseismic Structures of the Department of Engineering, Pontifical Catholic University of Peru in Lima, in collaboration with the UPM (Technical University of Madrid). This article shows the design process of the prototypes to test, including the sizing of the reinforcements, the characteristics of the tests and the results obtained. These results show that the IMS with adobe or brick remains stable with no significant cracks faced with a severe earthquake, with an estimated acceleration of 1.8 g. Este artículo presenta una aplicación del Sistema de Albañilería Integral (SAI) a la construcción de viviendas sismorresistentes y su estudio experimental. Para verificar su seguridad para su construcción en zonas sísmicas del tercer mundo se han ensayado dos prototipos, uno con adobe, y otro con ladrillo hueco. Se trata de una vivienda de 6x6x6 m3 y dos plantas que se construyen a escala 1/2. Los ensayos se realizaron en el Laboratorio de Estructuras Antisísmicas del Departamento de Ingeniería de la Pontificia Católica Universidad del Perú (PUCP) de Lima en colaboración con la UPM (Universidad Politécnica de Madrid). Este artículo muestra el proceso de diseño de los prototipos a ensayar, incluido el dimensionado de los refuerzos, las características de los ensayos y los resultados obtenidos. Estos resultados muestran que el SAI con adobe o ladrillo permanece estable sin grietas significativas ante un sismo severo, con una aceleración estimada de 1,8 g.

Practical case with regard to applying the functional and environmental method to low crest level, detached breakwaters

The research work as presented in this article covers the design of detached breakwaters since they constitute a type of coastal defence work with which to combat many of the erosion problems found on beaches in a stable, sustainable fashion. The main aim of this work is to formulate a functional and environmental (but not structural) design method, enabling the fundamental characteristics of a detached breakwater to be defined as a function of the effect it is wished to induce on the coast, and taking into account variables of a different nature (climate, geomorphology and geometry) influencing the changes the shoreline undergoes after its construction. With this article, it is intended to submit the final result of the investigation undertaken, applying the detached breakwater design method as developed to solving a practical case. Thus it may be shown how the method enables a detached breakwater’s geometric pre-sizing to be tackled at a place on the coast with certain climate, geomorphology and littoral dynamic characteristics, first setting the final state of equilibrium it is wanted to obtain therein after its construction.

Experience with PV-diesel hybrid village power systems in southern Morocco

In October 2002, under the auspices of Spanish Cooperation, a pilot electrification project put into operation two centralised PV-diesel hybrid systems in two different Moroccan villages. These systems currently provide a full-time energy service and supply electricity to more than a hundred of families, six community buildings, street lighting and one running water system. The appearance of the electricity service is very similar to an urban one: one phase AC supply (230V/50Hz) distributed up to each dwelling using a low-voltage mini-grid, which has been designed to be fully compatible with a future arrival of the utility grid. The management of this electricity service is based on a “fee-for-service” scheme agreed between a local NGO, partner of the project, and electricity associations created in each village, which are in charge of, among other tasks, recording the daily energy production of systems and the monthly energy consumption of each house. This register of data allows a systematic evaluation of both the system performance and the energy consumption of users. Now, after four years of operation, this paper presents the experience of this pilot electrification project and draws lessons that can be useful for designing, managing and sizing this type of small village PV-hybrid system

Dimensionamiento de una instalación eléctrica de un edificio de oficinas y almacén de productos farmacéuticos

En el presente proyecto se realiza el diseño y cálculo de la instalación eléctrica y el cálculo de luminarias, de un edificio de oficinas y almacén de productos farmacéuticos. Este diseño se precisa para el correcto desarrollo de la actividad de la nave industrial objeto de la instalación. Mediante la utilización de programas informáticos se pretende diseñar una guía para agilizar los procesos de dimensionamiento y cálculo para este tipo de proyectos. Al contar estos programas con una normativa totalmente actualizada, también agilizan el proceso de adecuación a la norma. En el cálculo de luminarias se consigue un cálculo muy aproximado de la potencia requerida, además de asegurar las condiciones lumínicas necesarias. También se tiene un cálculo muy exacto del circuito eléctrico que es fácil modificar a futuras ampliaciones. ABSTRACT The project´s aim is to make the design and calculations of the electrical and lighting installations, for a pharmaceutical warehouse. This design is necessary to ensure proper operational activity of the industrial warehouse, subject to the installation. By means of computer programs, it is intended to design a guide in order to speed up the processes of calculations and sizing of the electric wiring for this type of project. These programs are also fully updated, and therefore, the processes of adaptation to the legislation and regulations are made easier. In the calculation of the lighting, the software achieves a close approximation of the required power as well as ensuring the necessary light conditions. With this software we also achieve a very accurate calculation of the electrical circuit that is easy to modify to future expansions.

Diseño de un sistema de climatización para un edificio singular mediante el uso de fuentes de energía renovable

El proyecto consiste en el diseño del sistema de climatización de un edificio ubicado en la ciudad de Madrid que utilice la energía solar como fuente de calor y electricidad. El objetivo es que el edificio tenga un consumo energético lo más bajo posible y que utilice energías de origen renovable para su explotación. Se incluye el cálculo de cargas térmicas, el dimensionamiento del sistema de climatización y de los sistemas de captación de energía solar (térmica y fotovoltaica). Adicionalmente, se definen las principales características de un sistema de control centralizado que permita optimizar el rendimiento y monitorizar el funcionamiento de la instalación de forma continua. Se incluye el diseño de las instalaciones auxiliares con un grado de detalle suficiente que permita su valoración, tanto desde el punto de vista energético como económico. Como parte fundamental del proyecto, se extraen conclusiones acerca del ahorro energético de las instalaciones y se analiza la viabilidad económica de las inversiones. ABSTRACT The project covers the design of a Heating and Climatization System for a building located in the city of Madrid (Spain). The facilities will use solar energy as the main source for both heat and electricity. The main goals are to achieve the lowest possible energy consumption and to use renewable sources of energy to cover it. Calculation of thermal charges is included, together with the sizing of both the Climatization System and the Solar Energy (Thermal and PV) facilities. In addition, the main characteristics of a Centralized Control System are defined. This will help both to optimize the performance of the different systems involved and to monitor the operation. Design of all auxiliary systems is included with enough level of detail as to be able to evaluate them from both energetic and economic points of view. Paramount in this project is to be able to draw conclusions about the energy savings and the profitability (or not) of the main investments to be carried out

Metodología para maximizar la rentabilidad de una terminal marítima de contenedores a través de la optimización de su grado de automatización

Son generalmente aceptadas las tendencias actuales de maximización de la automatización para la adaptación de las terminales marítimas de contenedores a las cada vez mayores exigencias competitivas del negocio de transporte de contenedores. En esta investigación, se somete a consideración dichas tendencias a través de un análisis que tenga en cuenta la realidad global de la terminal pero también su propia realidad local que le permita aprovechar sus fortalezas y minimizar sus debilidades en un mercado continuamente en crecimiento y cambio. Para lo cual se ha desarrollado un modelo de análisis en el que se tengan en cuenta los parámetros técnicos, operativos, económicos y financieros que influyen en el diseño de una terminal marítima de contenedores, desde su concepción como ente dependiente para generar negocio, todos ellos dentro de un perímetro definido por el mercado del tráfico de contenedores así como las limitaciones físicas introducidas por la propia terminal. Para la obtención de dicho modelo ha sido necesario llevar a cabo un proceso de estudio del contexto actual del tráfico de contenedores y su relación con el diseño de las terminales marítimas, así como de las metodologías propuestas hasta ahora por los diferentes autores para abordar el proceso de dimensionamiento y diseño de la terminal. Una vez definido el modelo que ha de servir de base para el diseño de una terminal marítima de contenedores desde un planteamiento multicriterio, se analiza la influencia de las diversas variables explicativas de dicho modelo y se cuantifica su impacto en los resultados económicos, financieros y operativos de la terminal. Un paso siguiente consiste en definir un modelo simplificado que vincule la rentabilidad de una concesión de terminal con el tráfico esperado en función del grado de automatización y del tipo de terminal. Esta investigación es el fruto del objetivo ambicioso de aportar una metodología que defina la opción óptima de diseño de una terminal marítima de contenedores apoyada en los pilares de la optimización del grado de automatización y de la maximización de la rentabilidad del negocio que en ella se desarrolla. It is generally accepted current trends in automation to maximize the adaptation of maritime container terminals to the growing competitive demands of the business of container shipping. In this research, is submitted to these trends through an analysis taking into account the global reality of the terminal but also their own local reality it could exploit its strengths and minimize their weaknesses in a market continuously growing and changing. For which we have developed a model analysis that takes into account the technical, operational, financial and economic influence in the design of a container shipping terminal, from its conception as being dependent to generate business, all within a perimeter defined by the market of container traffic and the physical constraints introduced by the terminal. To obtain this model has been necessary to conduct a study process in the current context of container traffic and its relation to the design of marine terminals, as well as the methodologies proposed so far by different authors to address the process sizing and design of the terminal. Having defined the model that will serve as the basis for the design for a container shipping terminal from a multi-criteria approach, we analyze the influence of various explanatory variables of the model and quantify their impact on economic performance, financial and operational of the terminal. A next step is to define a simplified model that links the profitability of a terminal concession with traffic expected on the basis of the degree of automation and the kind of terminal. This research is the result of the ambitious target of providing a methodology to define the optimal choice of designing a container shipping terminal on the pillars of automation optimizing and maximizing the profitability of the business that it develops.

Static Pressure Impact on Aerodynamics of High Speed Railway Tunnels

A pressure wave is generated when a high speed train enters a tunnel. This wave travels along the tunnel back and forth, and is reflected at the irregularities of the tunnel duct (section changes, chimneys and tunnel ends). The pressure changes are associated to these waves can have an effect on passengers if the trains are not suitably sealed or pressurized. The intensity of the waves depends mainly on the train speed, and on the blockage ratio (train-section-to- tunnel-section area ratio). As the intensity of the waves is limited by regulations, and also by the effects on passengers and infrastructures, the sizing of the tunnel section area is largely influenced by the maximum train speed allowed in the tunnel. The aim of this study is to analyse the increase in cost in a tunnel due to the existence of this difference in ground level, and evaluate the increase of construction costs that this elevation might involve.

Storm evolution characterization for analysing stone armour damage progression

Storm evolution is fundamental for analysing the damage progression of the different failure modes and establishing suitable protocols for maintaining and optimally sizing structures. However, this aspect has hardly been studied and practically the whole of the studies dealing with the subject adopt the Equivalent triangle storm. As against this approach, two new ones are proposed. The first is the Equivalent Triangle Magnitude Storm model (ETMS), whose base, the triangular storm duration, D, is established such that its magnitude (area describing the storm history above the reference threshold level which sets the storm condition),HT, equals the real storm magnitude. The other is the Equivalent Triangle Number of Waves Storm (ETNWS), where the base is referred in terms of the real storm's number of waves,Nz. Three approaches are used for estimating the mean period, Tm, associated to each of the sea states defining the storm evolution, which is necessary to determine the full energy flux withstood by the structure in the course of the extreme event. Two are based on the Jonswap spectrum representativity and the other uses the bivariate Gumbel copula (Hs, Tm), resulting from adjusting the storm peaks. The representativity of the approaches proposed and those defined in specialised literature are analysed by comparing the main armour layer's progressive loss of hydraulic stability caused by real storms and that relating to theoretical ones. An empirical maximum energy flux model is used for this purpose. The agreement between the empirical and theoretical results demonstrates that the representativity of the different approaches depends on the storm characteristics and point towards a need to investigate other geometrical shapes to characterise the storm evolution associated with sea states heavily influenced by swell wave components.

Storm characterization for analyzing stone armour damage progression

Storm evolution is fundamental for analysing the damage progression of the different failure modes and establishing suitable protocols for maintaining and optimally sizing structures. However, this aspect has hardly been studied and practically the whole of the studies dealing with the subject adopt the Equivalent triangle storm. As against this approach, two new ones are proposed. The first is the Equivalent Triangle Magnitude Storm model (ETMS), whose base, the triangular storm duration, D, is established such that its magnitude (area describing the storm history above the reference threshold level which sets the storm condition),HT, equals the real storm magnitude. The other is the Equivalent Triangle Number of Waves Storm (ETNWS), where the base is referred in terms of the real storm's number of waves,Nz. Three approaches are used for estimating the mean period, Tm, associated to each of the sea states defining the storm evolution, which is necessary to determine the full energy flux withstood by the structure in the course of the extreme event. Two are based on the Jonswap spectrum representativity and the other uses the bivariate Gumbel copula (Hs, Tm), resulting from adjusting the storm peaks. The representativity of the approaches proposed and those defined in specialised literature are analysed by comparing the main armour layer's progressive loss of hydraulic stability caused by real storms and that relating to theoretical ones. An empirical maximum energy flux model is used for this purpose. The agreement between the empirical and theoretical results demonstrates that the representativity of the different approaches depends on the storm characteristics and point towards a need to investigate other geometrical shapes to characterise the storm evolution associated with sea states heavily influenced by swell wave components.

System Engineering Approach to Initial Design of LEO Remote Sensing Missions

The satellite remote sensing missions are essential for long-term research around the condition of the earth resources and environment. On the other hand, in recent years the application of microsatellites is of interest in many space programs for their less cost and response time. In microsatellite remote sensing missions there are tight interrelations between different requirements such as orbital altitude, revisit time, mission life and spatial resolution. Also, all of these requirements can affect the whole system level design characteristics. In this work, the remote sensing microsatellite sizing process is divided into three major design disciplines; a) orbit design, b) payload sizing and c) bus sizing. Finally, some specific design cases are investigated inside the design space for evaluating the effect of different design variables on the satellite total mass. Considering the results of the work, it is concluded that applying a systematic approach at the initial design phase of such projects provides a good insight to the not clearly seen interactions inside their highly extended design space

Propellantless de orbiting of space debris by bare electrodynamic tethers

A 3-year Project started on November 1 2010, financed by the European Commision within the FP-7 Space Program, and aimed at developing an efficient de-orbit system that could be carried on board by future spacecraft launched into LEO, will be presented. The operational system will deploy a thin uninsulated tape-tether to collect electrons as a giant Langmuir probe, using no propellant/no power supply, and generating power on board. This project will involve free-fall tests, and laboratory hypervelocity-impact and tether-current tests, and design/Manufacturing of subsystems: interface elements, electric control and driving module, electron-ejecting plasma contactor, tether-deployment mechanism/end-mass, and tape samples. Preliminary results to be presented involve: i) devising criteria for sizing the three disparate tape dimensions, affecting mass, resistance, current-collection, magnetic self-field, and survivability against debris itself; ii) assessing the dynamical relevance of tether parameters in implementing control laws to limit oscillations in /off the orbital plane, where passive stability may be marginal; iii) deriving a law for bare-tape current from numerical simulations and chamber tests, taking into account ambient magnetic field, ion ram motion, and adiabatic electron trapping; iv) determining requirements on a year-dormant hollow cathode under long times/broad emission-range operation, and trading-off against use of electron thermal emission; v) determining requirements on magnetic components and power semiconductors for a control module that faces high voltage/power operation under mass/volume limitations; vi) assessing strategies to passively deploy a wide conductive tape that needs no retrieval, while avoiding jamming and ending at minimum libration; vii) evaluating the tape structure as regards conductive and dielectric materials, both lengthwise and in its cross-section, in particular to prevent arcing in triple-point junctions.