Search results for " Bridge"
showing 10 items of 128 documents
BROWNIAN DYNAMICS SIMULATIONS WITHOUT GAUSSIAN RANDOM NUMBERS
1991
We point out that in a Brownian dynamics simulation it is justified to use arbitrary distribution functions of random numbers if the moments exhibit the correct limiting behavior prescribed by the Fokker-Planck equation. Our argument is supported by a simple analytical consideration and some numerical examples: We simulate the Wiener process, the Ornstein-Uhlenbeck process and the diffusion in a Φ4 potential, using both Gaussian and uniform random numbers. In these examples, the rate of convergence of the mean first exit time is found to be nearly identical for both types of random numbers.
The (micro) processes of integration as dialectic of structure and agency : the case of seconded national experts within the European Commission
2008
Masteroppgave i offentlig politikk og ledelse - Universitetet i Agder 2008 Micro-processes of integration – i.e. how agents develop identities, properties and decision-making behaviours preferred by a particular institution – have been a topic of significant scholarly debate. Most previous work builds on one underlying theoretical framework and thereby excludes (potentially important) elements lying outside it. My thesis attempts to contribute to the ongoing debate by developing a more holistic understanding of these processes, based on the dialectics of structure and agency and thereby positions actors’ decision-making behaviour on a continuum between ‘structural idiocy’ and ‘structural en…
Intervention strategies for the enhancement of the Peruvian route of the Inca royal path Qhapaq Ñan
2023
Qhapaq Ñan, a UNESCO World Heritage Site, was a complex administrative communication and transport system that connected the immense territory of the Inca empire for over 30 thousand km, intercepting sites of great historical and cultural interest today, first of all the Sanctuary of Machu Picchu. The consequences of climate change and the high tourist presence, which is mostly concentrated in Machu Picchu, are seriously jeopardizing the survival of this precious asset. The heavy rains that hit the monuments produce dangerous infiltrations of water between the masonry structures, compromising their stability; the transit of people along the paths and stairways erodes the rock and the soil. …
Stressing Sequence for Hanger Replacement of Tied-Arch Bridges with Rigid Bars
2022
The construction of bridges with suspenders, such as cable-stayed or tied-arch bridges, needs deep study of the prestressing forces to be applied to stays or hangers in all stages, depending on the construction technique adopted. In these cases, the main issue is the determination of the initial forces and optimization of the prestressing system in terms of stressing values and sequence. When the bridge is already built and suspenders have to be replaced for maintenance, a different problem has to be faced by the engineer, because the sequence of replacements and the values of the axial stresses depend very much on the service conditions of the bridge and on its historical evolution from co…
DC Bias Abatement in Dual Active Bridge Converter using Covalent Active and Passive Components
2022
The Dual Active Bridge (DAB) converter is the most attractive bidirectional DC-DC converter topology in the distribution network. However, the DC bias is the most common issue in the dual active bridge converter due to the sudden change in internal or external phase shift angles to regulate the power signal. Consequently, it will increase conduction losses, a core saturation problem of High-Frequency Transformer (HFT), and loss of Zero Voltage Switching (ZVS) operation. Therefore, this paper presents the DC bias abatement in the DAB converter using covalent active and passive components to alleviate these problems. The proposed method employs the series capacitor in the windings of HFT as t…
Current-Based Measurement Technique for High Sensitivity Detection of Resistive Bridges With External Balancing Through Control Voltages
2017
We present a novel approach based on differential measurements of dc currents with very high sensitivity suitable for the detection of very small variations of resistors in Wheatstone full-bridge configurations. External control voltages allow for the compensation of the bridge unbalancing avoiding the need of changing its elements so making the solution suitable for integrated sensor systems. The proposed current-based measurement technique has been implemented through three different circuits, in transimpedance configuration and without the use of any further amplification stage, employing only two active blocks that allow for a very high integration level. The main characteristics of the…
Die Dissoziationskonstanten von 2,2?-Dihydroxydiphenylmethanderivaten
1973
The pK-values of the first and second degree of dissociation of 2.2′-dihydroxy-5-methyl-3′.5′-dinitro-diphenylmethane, 2.2′-dihydroxy-5-methyl-5′-nitro-diphenylmethane and 2.2′-dihydroxy-5.5′-dimethyl-3′-nitro-diphenylmethane were determined in aqueous solution at 25°C spectrophotometrically. Comparing the observed pK-values with those of 2-methyl-4.6-dinitrophenol, 2-methyl-4-nitrophenol, 2.4-dimethyl-6-nitro-phenol and 2.4-dimethylphenol, we found a decrease of the values of pK1 and an increase of pK2. We explain this by the formation of an intramolecular hydrogen bridge which stabilizes the anion of the half dissociated form. This assumption is supported by the UV spectra.
Symplectic analysis of thin-walled curved box girders with torsion, distortion and shear lag warping effects
2022
Shear lag effect and torsional and distortional warping can significantly affect the performance of thin-walled curved box girders used in modern bridge engineering. The structural behaviour of these bridges exhibits complexity due to coupled bending and torsion together with warping effects of non-uniform torsion, distortion and shear lag. A practical method of analysis, based on the symplectic approach, with the same perspective as the Higher Order Beam Theories, is presented for overcoming the difficulties of numerical approaches via the Finite Element Method. In this paper, the Hamiltonian Structural Analysis method implements the analysis of the shear lag effect together with non-unifo…
Total ionizing dose (TID) evaluation of magnetic tunnel junction (MTJ) current sensors
2015
Abstract The paper shows an experimental study to know the behaviour of tunnel magnetoresistive effect-based current sensors configured in a Wheatstone bridge in response to irradiation. In particular the sensitivity, hysteresis, output offset voltage and input resistance are discussed when the sensors are submitted to a total irradiation dose of 43 krad with 36 krad/h dose rate. The same electrical parameters were studied subsequently once the irradiated sensors were submitted to an 80 °C annealing process. The studied TMR sensors are applied in a switched-mode power converter for space application.
Electrical Characterization of a Magnetic Tunnel Junction Current Sensor for Industrial Applications
2012
The objective of the work was the design of a Wheatstone bridge current sensor using MTJ as magnetoresistive elements. Each one of the four resistances of the bridge consists on 360 MTJ single elements connected in series for improved electrical robustness. A printed circuit board (PCB) was designed with a U-shaped copper trace placed under the PCB maintaining a 1.1 mm separation distance between sensor and trace. A 160% of tunnel magnetoresistance effect in the single junction and a 120% in its corresponding series elements connection has been achieved with a sensitivity of 9.2 Ω/Oe in a 65 Oe linear range. The DC sensor sensitivity in response to an external DC current sweeps of ±10, ±20,…