56 research outputs found
The role of female peace activists for the construction of peace in Colombia
Existen innumerables procesos para transformar el conflicto armado en Colombia. Mientras desde la política han intentado de resolverlo por medios militares y políticos, como el Acuerdo de Paz de 2016, las organizaciones de mujeres están trabajando con y por la comunidad, la gente en las regiones y barrios afectados. Esta tesis examina la construcción feminista de la paz a través del trabajo de las mujeres a nivel de base, utilizando el estudio de caso de cinco activistas en Medellín. Muestra que tanto el significado de la paz como su construcción se desvían de los procesos formales que suelen ser dominados por los hombres. Para las activistas, la paz se construye con lazos de amor, que significa empatía, cuidado, respeto, tolerancia y solidaridad. La construcción se hace siempre colectivamente y empieza por un trabajo individual antes de poder iniciar procesos de paz en la familia y la comunidad.There are countless approaches to transforming the armed conflict in Colombia. While politicians have tried to do so through military and political means, such as the peace agreement of 2016, women's organisations are working with the people in the affected regions and neighbourhoods. This thesis thus looks at feminist peace construction through women's work at the grassroots level, using the case study of five activists in Medellín. It shows that both the meaning of peace and its construction deviate from formal and male-dominated processes. For the activists, peace is built on ties of love, which means empathy, care, respect, tolerance and solidarity. The construction always happens collectively and starts with oneself before one can initiate peace processes in the family and the community
Lean satellite design for amateur communications payload in the ESA ESEO mission
AMSAT-UK and the Surrey Space Centre are cooperating in delivering an educational communication payload for the ESA European Student Earth Orbiter (ESEO) mission, comprising a payload computer, an L-band receiver and a VHF transmitter. The primary purpose of the payload is to provide downlink telemetry that can be easily received by schools and colleges for educational outreach purposes [1]. Common space industry standards such as European Cooperation for Space Standardization (ECSS) consist of a large number of documents that were primarily written for large-scale space missions. Academic space projects cannot follow these design guidelines due to a lack of sufficient expertise, human resources, facilities or equipment. However, many projects were successfully developed, launched and operated with major deviations from ECSS standards. A recently published CubeSat standard consists of tailored ECSS requirements with the aim to improve the applicability of these specifications to small satellite projects. These, however, are still incompatible with the limited working environment of most university projects. In recent years, a `lean satellite' design approach that utilises non-traditional, risk-taking development and management was proposed by Cho et al. [2] to address these issues. This design approach was successfully applied by the AMSAT project team to develop a proto-flight model of the payload which entailed an improvement of customer specification compliance from 81% to 86% with respect to the engineering model. This method allowed a low cost and fast development process as well as passing all functional and environmental tests without major issues. A key finding was that despite having superior facilities, equipment and expertise compared to most academic CubeSat teams, only an overall compliance of 82% to the CubeSat standard and 57% to the analysed set of ECSS specifications could be achieved. This shows the challenge small space projects face when following conventional industry specifications such as ECSS which are written for traditional space missions. Following this, it is recommended to further promote the development of a new ISO standard for lean satellite design which could ease the development process and reliability of small space projects that struggle to fully comply to ECSS or CubeSat specifications
Simplify Your Experiments: Simple Three Electrode and Full Cell Measurements for Better Understanding of Lithium Ion Battery Materials
Simple Experiments Giving Deep Insights into Capacity Fade and Capacity Loss Mechanisms of Li Battery Materials
Running out of lithium? A route to differentiate between capacity losses and active lithium losses in lithium-ion batteries
Active lithium loss (ALL) resulting in a capacity loss (QALL), which is caused by lithium consuming parasitic reactions like SEI formation, is a major reason for capacity fading and, thus, for a reduction of the usable energy density of lithium-ion batteries (LIBs). QALL is often equated with the accumulated irreversible capacity (QAIC). However, QAIC is also influenced by non-lithium consuming parasitic reactions, which do not reduce the active lithium content of the cell, but induce a parasitic current. In this work, a novel approach is proposed in order to differentiate between QAIC and QALL. The determination of QALL is based on the remaining active lithium content of a given cell, which can be determined by de-lithiation of the cathode with the help of the reference electrode of a three-electrode set-up. Lithium non-consuming parasitic reactions, which do not influence the active lithium content have no influence on this determination. In order to evaluate this novel approach, three different anode materials (graphite, carbon spheres and a silicon/graphite composite) were investigated. It is shown that during the first charge/discharge cycles QALL is described moderately well by QAIC. However, the difference between QAIC and QALL rises with increasing cycle number. With this approach, a differentiation between “simple” irreversible capacities and truly detrimental “active Li losses” is possible and, thus, Coulombic efficiency can be directly related to the remaining useable cell capacity for the first time. Overall, the exact determination of the remaining active lithium content of the cell is of great importance, because it allows a statement on whether the reduction in lithium content is crucial for capacity fading or whether the fading is related to other degradation mechanisms such as material or electrode failure
Lean Qualification of the AMSAT-UK Software Radio Payload
The European Student Earth Orbiter (ESEO) is a micro-satellite mission to Low Earth Orbit and is being developed, integrated, and tested by European university students as an ESA Education Office project. AMSAT-UK and Surrey Space Centre are contributing to the mission with a transceiver and transponder similar to that of FUNcube-1 with the addition of utilising an Atmel AT32 processor for packet software-redundancy, baseband processing, forward error correction, and packet forming; acting as a step towards software defined radio using automotive microprocessors [1]. As on the FUNcube-1 satellite, the telemetry formats and encoding schemes presented utilize a large ground network of receivers on the VHF downlink and conforms to 1200 bps and a new 4800 bps redundant downlink for the rest of the spacecraft. The uplink is on L-band using bespoke partial-CCSDS frames. This paper describes the lean satellite design approach introduced by Cho et al. [2] for hardware and software development and testing of the proto-flight model (PFM) payload computer. Furthermore, it assesses the compliance of the project to customer and ESA specifications and discusses the applicability of these standards. Finally, lessons learned are elaborated to provide guidance for future small satellite projects. Through multiple student projects, it was possible to successfully develop a proto-flight model using the lean satellite design approach which entailed an improvement of customer specification compliance from 81% to 86% comparing to the engineering model. In software, utilising the Google Test Suite for verification of the SDR functions and FreeRTOS tools allowed students to optimize processor load margins to 30% when operating parallelized ADC and DAC, and CAN-open telemetry chains and exploring stable memory operations. A further finding was that in Summer 2017, there was an overall compliance of 82% to the CubeSat standard and 57% to the analysed set of ECSS specifications could be achieved. The poorer compliance in ECSS is due to the incomplete environmental testing at that time. The unfunded and student-based nature of the project places significant challenges when compared to conventional missions – but this was outweighed by the ESEO flight opportunity. Following this, we recommended to further the development of a new ISO standard for lean satellite design as initiated by Cho et al. [3] which eases the development process and reliability of small space projects that struggle to fully comply to ECSS or CubeSat specifications. ESA have since defined a subset of ECSS Specifications for educational and CubeSat missions.</p
Pre-Lithiation Strategies for Rechargeable Energy Storage Technologies: Concepts, Promises and Challenges
Abstract: In order to meet the sophisticated demands for large-scale applications such as electro-mobility, next generation energy storage technologies require advanced electrode active materials with enhanced gravimetric and volumetric capacities to achieve increased gravimetric energy and volumetric energy densities. However, most of these materials suffer from high 1st cycle active lithium losses, e.g., caused by solid electrolyte interphase (SEI) formation, which in turn hinder their broad commercial use so far. In general, the loss of active lithium permanently decreases the available energy by the consumption of lithium from the positive electrode material. Pre-lithiation is considered as a highly appealing technique to compensate for active lithium losses and, therefore, to increase the practical energy density. Various pre-lithiation techniques have been evaluated so far, including electrochemical and chemical pre-lithiation, pre-lithiation with the help of additives or the pre-lithiation by direct contact to lithium metal. In this review article, we will give a comprehensive overview about the various concepts for pre lithiation and controversially discuss their advantages and challenges. Furthermore, we will critically discuss possible effects on the cell performance and stability and assess the techniques with regard to their possible commercial exploration
TV-Satelliten-Empfangstechnik fuer den Praktiker
With appendix: New television standard D2-MACCopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLE3. rev. and enl. ed.DEGerman
New insights into pre-lithiation kinetics of graphite anodes via nuclear magnetic resonance spectroscopy
Pre-lithiation of anode materials can be an effective method to compensate active lithium loss which mainly occurs in the first few cycles of a lithium ion battery (LIB), due to electrolyte decomposition and solid electrolyte interphase (SEI) formation at the surface of the anode. There are many different pre-lithiation methods, whereas pre-lithiation using metallic lithium constitutes the most convenient and widely utilized lab procedure in literature. In this work, for the first time, solid state nuclear magnetic resonance spectroscopy (NMR) is applied to monitor the reaction kinetics of the pre-lithiation process of graphite with lithium. Based on static 7Li NMR, we can directly observe both the dissolution of lithium metal and parallel formation of LiCx species in the obtained NMR spectra with time. It is also shown that the degree of pre-lithiation as well as distribution of lithium metal on the electrode surface have a strong impact on the reaction kinetics of the pre-lithiation process and on the remaining amount of lithium metal. Overall, our findings are highly important for further optimization of pre-lithiation methods for LIB anode materials, both in terms of optimized pre-lithiation time and appropriate amounts of lithium metal
Satelliten-Fernsehen Bericht ueber Experimente mit den Satelliten OTS 2, Gorizont, Meteosat 2
Copy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLE3. ed.DEGerman
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