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The rock mass viscous behaviour during tunnel construction is discussed. Initially, a brief introduction to the squeezing phenomenon and its association with the related one of creep is provided. Then, existing simplified models of rheological rock mass behaviour are presented and analysed. The range of the viscoelastic rock parameters identified in the literature for weak rocks is also given and
Gold nanoparticles are of great interest for various nanoelectronic applications, e.g., for making single electron transistors or very fine leads to molecular size entities. For this and other applications, it is important that all particles have controllable size and shape. In this paper, we describe the production of size-selected gold aerosol particles in the 20 nm range made by evaporation in
In this paper we investigate the feasibility of a fabrication route to produce nanocrystals of compound material with incongruent sublimation behavior via the simple evaporation of the powder of the compound. The generation of stoichiometric particles would only be possible if the particle formation occurs at temperatures below the incongruent sublimation point. Our experiments, done on three diff
We have used carbon nanotubes to electrically contact a 7 nm gold particle by scanning-probe manipulation. The result was a single-electron transistor showing a periodic modulation of the current as a function of gate voltage for temperatures up to ∼200 K, with the particle responsible for the main features of the electron transport. This interpretation could be verified when the particle was remo
We have developed a technique for the synthesis of size-selected, GaAs, epitaxial nano-whiskers, grown on a crystalline substrate. As catalysts, we used size-selected gold aerosol particles, which enabled us to fully vary the surface coverage independently of the whisker diameter. The whiskers were rod shaped, with a uniform diameter between 10 and 50 nm, correlated to the size of the catalytic se
Arrangements of nanometer-sized particles were obtained on plane oxidized silicon substrates by direct deposition from the gas phase. The particles were attracted onto charge patterns created by contact charging. Monodisperse, singly charged indium aerosol particles with a diameter of 30 nm were used as a test case to illustrate this process. Due to the surface treatment, the deposition is highly
Nanometer-sized particles of W are of interest in semiconductor device research, where such particles may store electrons inside heteroepitaxially defined structures. In this paper, we present results concerning W particles produced by thermal decomposition of tungsten hexacarbonyl. By the described method, it was possible to produce size-selected, single-crystalline W particles in the size range
Nanocrystals of indium phosphide, with diameters of around 10nm, have been produced via an aerosol route. The method is based on the formation of monodisperse indium droplets and the subsequent reaction with phosphine at elevated temperature. The size of the final InP nanocrystal is self-limited by the size of the introduced size-selected In droplet. This size can be tuned carefully, thus this met
Single-electron transistors (SET) rely for their functionality on extreme control of lithography and lateral positioning as well as of properties of the building blocks from which the devices are built. By an aerosol-based nanoparticle fabrication we can prepare nanocrystals down to sub-10nm dimensions with metallic or semiconducting character, as well as having a core + shell design for definitio
In this paper we present a fabrication route to produce size-selected III-V semiconductor nanocrystals via a simple, reliable, and efficient aerosol route. Since this approach includes the reaction of aerosol particles and a self-organized growth of a new compound, all in the aerosol phase, we call this process aerotaxy. Size-selected nanocrystals of different III-V compounds in a diameter range b
An investigation on the different levels of interpretation of medieval architectural iconography. The architecture and sculpture of Lund cathedral is related to function, history, politics and religion.
La conferencia plantea la necesidad de un tránsito hacia otras formasde aplicar la semiótica en el diseño.La semiótica del diseño con enfoque agentivo ofrece elementos paraconocer en detalle la experiencia humana y las condiciones que determinanla construcción de sentido que emerge cuando un usuario integra artefactosa dicha experiencia para el cumplimiento de sus objetivos.El asumir un enfoque se
This research aims to encourage interdisciplinary and inter-institutionalcollaborative work through the design and manufacture of an electricvehicle. The goal is to design an experimental vehicle concept in order toimprove sustainable mobility in Bogotá.Industrial Center of Maintenance and Manufacturing CIMM, SENABoyacá, is manufacturing the prototype designed by the team ofresearchers, while priv
Laminar burning velocities of syngas/air premixed flames, varying with H2/CO ratio (from 5/95 to 75/25) and N2 or CO2 dilution rate (from 0% to 60%), were accurately measured using a Teflon coated Heat Flux burner and OH-PLIF based Bunsen flame method. Experiments were carried out at atmospheric pressure and room temperature, with fuel/air equivalence ratios ranging from fuel-lean to fuel-rich. Co
Car-sharing systems with electric vehicles are an alternativeto reduce commuting times in big cities and also to mitigateair pollution. Car-sharing exists in 1100 cities around theworld. These systems have had positive effects in the cities,replacing between 9 and 23 private vehicles for each car. Thisdocument proposes a public car-sharing system for Bogotá.The article focuses on the design and ma
A simple experiment to characterize the gating properties of X-ray area detectors using pulsed X-ray sources is presented. For a number of time-resolved experiments the gating uniformity of area detectors is important. Relative gating delays between individual modules and readout chips of PILATUS2 series area X-ray detectors have been observed. For three modules of a PILATUS300K-W unit the maximum
