0.2µm T-gate InP/InGaAs/InP pHEMT with an InGaP Diffusion Barrier Layer Grown By LP-MOCVD Using an N2-carrier

in Proceedings of the 26th European Solid State Devices Research Conference, Bologna, Italy, 1996 (1996)

100 Jaar Prandtl-Wig: De draagkrachtfactoren

in Geotechniek (2017), December

In 1920 publiseerde Prandtl een artikel over het bezwijken van een materiaal onder een strookbelasting. De bezweken grondmoot is hierbij verdeeld in drie zones, die tezamen de zogenoemde Prandtl-wig ... [more ▼]

In 1920 publiseerde Prandtl een artikel over het bezwijken van een materiaal onder een strookbelasting. De bezweken grondmoot is hierbij verdeeld in drie zones, die tezamen de zogenoemde Prandtl-wig vormen. Prandtl heeft nooit aan de funderingstechnische toepassing gedacht, maar geotechnici vertalen deze oplossing nu als een analytische oplossing voor de draagkracht van de grond onder een strookfundering. Deze oplossing is uitgebreid door Reissner met een bovenbelasting naast de funderingsstrook en door Keverling Buisman en Terzaghi voor het grondgewicht. Terzaghi schreef dit als eerste met drie gescheiden draagkrachtfactoren en Meyerhof als eerste met “inclinatie-” en “shape” factoren, voor de drie afzonderlijke draagkrachtcomponenten; cohesie, bovenbelasting en het grondgewicht. Deze schrijfwijze werd later door Brinch Hansen overgenomen. In dit artikel zijn een groot aantal numerieke berekeningen gemaakt om het bezwijkmechanisme van de Prandtl-wig en de bijbehorende draagkrachtfactoren te controleren. Het blijkt dat het Prandtl-wig bezwijkmechanisme juist is, maar niet in alle gevallen. Ook blijkt dat de analytische oplossingen voor de draagkrachtfactoren die tegenwoordig worden gebruikt, alleen juist zijn voor grond met een onrealistisch hoge dilatantiehoek. [less ▲]

100 Years of Prandtl's Wedge

Book published by IOS Press (2018)

The biggest problem for a shallow foundation, just as for any other type of foundation, is a failure due to an overestimation of the bearing capacity. This means that the correct prediction of the bearing ... [more ▼]

The biggest problem for a shallow foundation, just as for any other type of foundation, is a failure due to an overestimation of the bearing capacity. This means that the correct prediction of the bearing capacity of the foundation is often the most important part of the design of a civil structure. That is why the publication by Prandtl in 1920 about the hardness of a plastic body, was a major step in solving the bearing capacity of shallow foundations, although it is well possible that he never realised this, because his solution was not made for civil engineering purposes, but for mechanical purposes. Over the last 100 years, a lot of extensions have been made, for example with inclination factors and shape factors. Also many laboratory experiments have been done and numerical calculations have been made. Some even try to extrapolate the failure mechanism for shallow foundations to the failure mechanism around the tip of a pile. All this scientific work leads back to the first publication by Ludwig Prandtl in 1920. This book, “100 Years of Prandtl’s Wedge”, is intended for all those who are interested in these fundamentals of foundation engineering and their history. The Appendices include a copy of Prandtl’s Über die Härte plastischer Körper and of Reissner’s publication of 1924, Zum Erddruckproblem. [less ▲]

11,8-100% Rural Renewable Energy and Power Supply and its Influence on the Luxembourgish Power System

Poster (2015, March 10)

Introduction; Currently, the majority of countries tries to reduce their dependency on fossil fuels by the introduction of renewable resources in their energy systems. In the following the relatively ... [more ▼]

Introduction; Currently, the majority of countries tries to reduce their dependency on fossil fuels by the introduction of renewable resources in their energy systems. In the following the relatively small Luxembourgish electricity system is analysed (0.55 Mio Inhabitants). Current power-system-models mainly focus on larger systems, due to the unavailability of specific consumption-data. Prices and effects on the Luxembourgish power system of different supply scenarios for rural-private households are analysed. Methodology; A linear optimisation for the minimum-cost of the power-supply of all villages with the following renewable energy resources: wind- (max.100kW), solar-PV- and hydrokinetic-power is made. The electricity-demand scales with the number of inhabitants and agricultural-consumers. The wind-power-potential differs with the location of the village. The solar-radiation is assumed to be the equal over the country, due to the small size of approximately 80 by 50 km. The hydrokinetic turbines complete the supply where a village is located close to a river. Results; The minimum cost of the specific village power-supply is the result of the optimization. The installation- and maintenance-cost of each renewable technology are considered. The whole number of rural Luxembourgish private households is considered and their power contribution to the system is estimated for different renewable energy supply scenarios, namely from 11,8% to 100% renewable-energy-scenarios. For each scenario the power exchanged from the village to the grid is calculated in 15-min-steps for 9-years, the amount differs widely with the amount of applied technologies. Discussion; Due to the high share of imported electricity of about 80% in the recent years, every consideration of national power generation does not harm the supply security. Conclusion; Luxembourg is a good model country to analyse the high share of distributed, renewable generators, due to its structure of rural and civic regions and their effects on a central European region with a high electricity consumption. [less ▲]

16 GHz Bandwidth MSM Photodetector and 45/85 GHz fT/fmax HEMT Prepared on an Identical InGaAs/InP Layer Structure

in Electronics Letters (1996), 32

2-stage process for a higher flexibility of biogas-plants

Scientific Conference (2016, September 21)

The increasing part of renewable energy in the electricity production mix with its known fluctuations of wind and photovoltaic plants is leading to an enlarged discrepancy of production and consumption ... [more ▼]

The increasing part of renewable energy in the electricity production mix with its known fluctuations of wind and photovoltaic plants is leading to an enlarged discrepancy of production and consumption. Up to now the electricity production of biogas plants is more or less constant but could be used in future more to balance the energy production by using higher biogas storage capacity. An interesting alternative could be a 2 stage process. The 1st stage is operated at higher loadings and low pH where mainly substrate hydrolysis takes place and relatively small quantities of H2/CO2 gas are produced. The effluent shows high concentrations (total > 10 g FA/l) of mainly butyric and caproic acid which could easily and stable be temporarily stored in liquid-tanks. The transformation of the acidic intermediates from hydrolysis to biogas (and finally electricity) in the 2nd stage is faster compared to the traditional fermentation. The storage capacity for the acidic intermediates is more than 10 times smaller compared to the temporary storage of biogas. [less ▲]

2015 Workshop on Socio-Technical Aspects in Security and Trust, STAST 2015, Verona, Italy, July 13, 2015

Scientific Conference (2015, July 13)

2018 25th International Conference on Telecommunications (ICT)

in 2018 25th International Conference on Telecommunications (ICT) (2018)

The anticipated exponential growth in network traffic is posing significant challenges for the implementation of 5G networks. In this context, a major problem is the backhaul network which acts as a ... [more ▼]

The anticipated exponential growth in network traffic is posing significant challenges for the implementation of 5G networks. In this context, a major problem is the backhaul network which acts as a bottleneck preventing the efficient flow of ultra-dense and heavy traffic between the end users and the core network. Spectrum scarcity has emerged as the primary problem encountered when trying to accommodate the traffic upsurge. In this paper, we investigate the carrier allocation problem in the context of Integrated Satellite-Terrestrial Backhaul (ISTB) networks. In particular, we consider the satellite component to be integrated with the conventional terrestrial wireless backhaul network thus providing evident benefits in terms of data-offloading. To enhance the overall spectral efficiency of the proposed network, we consider that both terrestrial and satellite segments operate in the Ka band, where the sharing between terrestrial microwave links and satellite communications is already allowed. A novel carrier allocation algorithm based on fairness is proposed, which ensures that all backhaul links are continuously active to satisfy the operator's coverage needs. The problem is NP-hard by definition. As a consequence, we present a two-step sequential carrier allocation strategy specifically tailored to tackle the interference issues emerging from the spectral co-existence. Supporting results based on numerical simulations show that the proposed carrier allocation can provide a 2x improvement in terms of spectral efficiency when compared to benchmark terrestrial-only backhaul networks. [less ▲]

2018 Lab Report Computational Mechanics Legato-team and Z-team

Report (2018)

2D Tool-Path Generation Method for Multi-Axis Milling Machine using ToF camera

Scientific Conference (2014, September 12)

Multi-axis machines are known for their precise production of complex parts, where multi-tool are working in the same area or static workpiece support or clamping parts, may cause collision problems. It ... [more ▼]

Multi-axis machines are known for their precise production of complex parts, where multi-tool are working in the same area or static workpiece support or clamping parts, may cause collision problems. It is therefore necessary to identify potential collision risks and avoid them in an efficient way, which may cause production stops and machinery damage. This research study has been focusing on safe non-functional (rapid) tool-path generation for multi-axis milling machine, where no efficient automatic collision avoidance solution exists (in the literature). A 3D Time of Flight (TOF) camera attached into the machine will be able to sense any unwanted situation in the manufacturing environment and provide rapid and automatic solution to detect and avoid collisions for safe tool movements during production. In the presence of obstacles, the proposed approach will provide decisions regarding tool-path correction and improvement automatically. The proposed algorithm based on 3D vision concept is also able to take into account unknown obstacle shape, size during production but dynamic aspects of the scene will be treated in future. The concept presented take into account the 3D information from the scene for traversal safe tool-paths generation for a static environment as an initial application, which will be adapted to more complex real machining scenarios by integrating it with STEP-NC technology in future. [less ▲]