12,072 research outputs found
Behavior of RC beams patch repaired and strengthened with FRP composites : a numerical study
No full textIncludes bibliographical references.Reinforced concrete (RC) beams get deteriorated and become deficient mainly due to corrosion of steel reinforcements, poor maintenance and design, earthquakes and aging. Patch repair and structural strengthening using fiber reinforced polymers (FRP) have been increasingly adopted all over the world as an economical solution to upgrade the load carrying capacity of such beams. However, the failure modes of such repaired and strengthened RC beams are governed by brittle and sudden premature debonding which involves separation of external reinforcement; i.e. FRP and RC beam. Different researchers have used different approaches including experimental, analytical and numerical to investigate the behavior of patch repaired and FRP strengthened RC beams. It is noteworthy that there are no such numerical studies that investigated the effect of patch repair. In this study, a numerical investigation was carried out using the commercial finite elements analysis software ABAQUS with the aim of investigating the overall behavior of RC beams patch repaired and strengthened with FRP plates including the failure mechanisms
Modelling delay and noise in arbitrarily coupled RC trees.
No full textClosed-form equations for second-order transfer functions of general arbitrarily coupled resistance-capacitance (RC) trees with multiple drivers are reported. The models allow precise delay and noise calculations for systems of coupled interconnects with guaranteed stability and represent the minimum complexity associated with this class of circuits. Their accuracy is extensively compared against other relevant models and is found to be better or comparable to more expensive models. All results are derived from a theoretical approach, and their physical basis is examined. The simplicity, accuracy, and generality of the models make them suitable for use in early signal integrity analyses of complex systems and incremental physical optimization
Rb and Rc Crises
No full textThe Rb and Rc crises described by Kaoru Hagiwara in hep-ph/9512425 [2] can be resolved by the T-quark mass value of 130 GeV and the αs(MZ) value of 0.106 of the D4 − D5 − E6 model described in hep-ph/9501252 [5] and quant-ph/9503009 [6]. c○1995 Frank D. (Tony) Smith, Jr., Cartersville, Georgia USA1 Introduction. During 1995, precision electroweak data have confirmed the predictions of the Standard Model, with no new physics, with the possible exception of the two observables Rb and Rc. In his recent review, Kaoru Hagiwara [2] has described the situation i
Measurable parameters for performance of correded and repaired RC beams under load
No full textIncludes abstract.Includes bibliographical references.Structural engineers and asset managers rely on measurable parameters developed by researchers to predict residual load-bearing capacities of corroding in-service RC structures and to assess repair-effectiveness. Laboratory research that was used to develop these measurable parameters varied between researchers and in most cases, did not represent in-service conditions. As a result, they found different relations between measurable and non-measurable parameters which are unsafe and/or engineers find difficult to apply to in-service structures. A holistic research that emulates in-service conditions was therefore developed. Parameters that were looked at were corrosion crack widths and longitudinal strains together with their derivatives
A Compact 10-MHz RC Frequency Reference With a Versatile Temperature Compensation Scheme
No full textThis article presents the design and implementation of a compact CMOS RC frequency reference. It consists of a frequency-locked loop (FLL) that locks the period of a voltage-controlled oscillator (VCO) to the time an RC network takes to charge to a reference voltage. Conventionally, an RC time constant with a near-zero temperature coefficient (TC) is realized by using a trimmed network of resistors with different TCs. In this work, such a network is used to realize a temperature-dependent reference voltage whose TC cancels that of a single-resistor RC time constant. Compared with the conventional approach, which requires resistors with TCs of opposite polarity, the proposed approach can be implemented with resistors with TCs of similar polarity, and so it can be implemented in most CMOS processes. To compensate for RC spread, a trimmed capacitor is used to adjust the nominal frequency. Two prototype chips were made, one based on p- /n-polysilicon resistors and other based on silicided/p-diffusion resistors. Fabricated in a standard 180-nm CMOS technology, the polysilicon-based prototype has an active area of 0.01 mm2 and an absolute inaccuracy of ±2800 ppm from -45 °C to 125 °C with a fixed TC-trim and a one-point frequency trim. After one week of accelerated aging at 150 °C, however, significant drift (5000 ppm) was observed. The diffusion-based prototype exhibits greater inaccuracy (±14 400 ppm) but much less drift (600 ppm).Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
‘Parabolic’ trapped modes and steered Dirac cones in platonic crystals
No full textThis paper discusses the properties of flexural waves governed by the biharmonic operator, and propagating in a thin plate pinned at doubly periodic sets of points. The emphases are on the design of dispersion surfaces having the Dirac cone topology, and on the related topic of trapped modes in plates for a finite set (cluster) of pinned points. The Dirac cone topologies we exhibit have at least two cones touching at a point in the reciprocal lattice, augmented by another band passing through the point. We show that these Dirac cones can be steered along symmetry lines in the Brillouin zone by varying the aspect ratio of rectangular lattices of pins, and that, as the cones are moved, the involved band surfaces tilt. We link Dirac points with a parabolic profile in their neighbourhood, and the characteristic of this parabolic profile decides the direction of propagation of the trapped mode in finite clusters
A CMOS Dual-RC frequency reference with ±250ppm inaccuracy from -45°C to 85°C
No full textTo comply with wired communication standards such as USB, SATA and PCI/PCI-E, systems-on-chip require frequency references with better than 300ppm accuracy. LC-based references achieve 100ppm accuracy [1], but suffer from high power consumption (∼20mW). Thermal diffusivity (TD) references require less power (∼2mW), at the expense of less accuracy (1000ppm) [2]. RC-based references offer the lowest power consumption, but their accuracy is typically limited to ∼0.1% [3]. In RC relaxation oscillators, comparator offset and delay are the major sources of inaccuracy [4,5]. References based on frequency-locked loops (FLLs) circumvent these by locking an oscillator's frequency to the time-constant of an RC filter, but their accuracy is then limited by the nonlinear temperature dependency of on-chip resistors [3,6].Session 3.3 Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Instrumentation(OLD)Applied Quantum ArchitecturesMicroelectronic
Influence of FRP anchors on the strength and ductility of FRP-strengthened RC slabs
No full textExtensive experimental verification has shown that existing reinforced concrete (RC) members can be strengthened with externally bonded fibre-reinforced polymer (FRP) composites. Two well documented limitations to the strengthening technology though are premature FRP debonding failure and non-ductile member behaviour. A recent study by Smith et al. [1] showed anchors made from FRP (also known as FRP anchors) to be effective in delaying debonding and also effective in enhancing the deformability (and ductility) of RC slabs strengthened in flexure with FRP plates. This paper extends the work of Smith et al. by reporting the results of tests on 10 FRP-strengthened RC slabs anchored with FRP anchors of varying geometry and positioning. Optimal arrangements of anchors in this second series of tests have enabled the load and deflection capacities of the FRP-strengthened slabs, in relation to the unanchored but strengthened control slab, to be enhanced by up to 44% and 216%, respectively. Strain utilisation of the FRP plate has also been shown to increase from 44% of the flat coupon strain capacity for the unanchored but strengthened control slab to 95% for an optimally anchored FRP-strengthened slab
Obsessive compulsive disorder in children and young people: experiences of children with OCD and the involvement of families in treatment
No full textOsservazioni comparative sull'organo sotto commessurale di anfibi anuri ed urodeli adulti
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