3,604 research outputs found
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
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
A meta-analysis of the effectiveness of the opioid receptor antagonist alvimopan in reducing hospital length of stay and time to GI recovery in patients enrolled in a standardized accelerated recovery program after abdominal surgery
No full textA 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
Real closed fields and models of Peano Arithmetic
No full textShepherdson [14] showed that for a discrete ordered ring I , I is a model of IOpen iff I is an integer part of a real closed ordered field. In this paper, we consider integer parts satisfying PA. We show that if a real closed ordered field R has an integer part I that is a nonstandard model of PA (or even IΣ4),then R must be recursively saturated. In particular, the real closure of I , RC(I ), is recursively saturated. We also show that if R is a countable recursively saturated real closed ordered field, then there is an integer part I such that R = RC(I ) and I is a nonstandard model of PA
Simulation of RC beams with mechanically fastened FRP strips
No full textAbstract not availableDaniel Knight, Phillip Visintin, Deric J. Oehlers, M.S. Mohamed Al
Simulating RC beams with unbonded FRP and steel prestressing tendons
No full textAbstract not availableD. Knight, P. Visintin, D.J. Oehlers, M.S. Mohamed Al
Grain size dependency in the occurrence of sand waves
No full textSandy shallow seas, like the North Sea, are very dynamic. Several morphological features are present on the bed, from small ripples to sand waves and large tidal sandbanks. The larger patterns induce significant depth variations that have an impact on human activities taking place in this area. Therefore, it is important to know where these large-scale features occur, what their natural behaviour is and how they interact with human activities. Here, we extend earlier research that compares the results of an idealized model of large-scale seabed patterns with data of seabed patterns in the North Sea. The idealized model is extended with a grain size dependency. The adaptations lead to more accurate predictions of the occurrence of large-scale bed forms in the North Sea. Therefore, grain size dependency and, in particular, critical shear stress are important to explain the occurrence of sand waves and sandbanks in the North Sea
Experimental and theoretical investigation of crack width calculation methods for RC ties
No full textThis paper theoretically and experimentally investigates the semi-empirical formulas recommended by Eurocode 2 (EC2), fib Model Code 2010 (MC2010), and Eurocode 2 with the German National Annex (DIN) for calculating crack widths in reinforced concrete. It is shown that the formulas can be derived from the principles for the idealized behavior of RC ties. However, instead of explicitly solving the resulting differential equations, the use of simplifications leads to inconsistent formulas. An experimental study was carried out involving the testing of eight RC ties to discover the modeling uncertainty of the formulas. It was found that EC2 substantially overestimated the crack widths for the RC ties. MC2010 and DIN seemed to predict the crack widths better, but gave rather a large number of nonconservative crack width predictions. These experimental results, combined with the theoretical study, suggest that a more consistent calculation model should be formulated by explicitly solving the resulting differential equation.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.Applied Mechanic
A prospective case–control study of extralevator abdominoperineal excision (ELAPE) of the rectum versus conventional laparoscopic and open abdominoperineal excision: comparative analysis of short-term outcomes and quality of life
No full textBackground: Conventional abdominoperineal excision (APE) of the rectum is associated with higher circumferential resection margin (CRM) involvement, increased local recurrence, and reduced survival compared to anterior resection. A more radical extralevator APE (ELAPE) technique may improve oncological outcome. However, this technique may confer additional morbidity, and little comparative data on short-term outcomes have been reported. This study compares short-term outcomes and quality of life (QOL) after open and laparoscopic ELAPE, laparoscopic APE (LAPE), and open APE (OAPE).Methods: Data on all ELAPE and 10 consecutive LAPE and OAPE were extracted from a prospective database. Perioperative care and follow-up were standardized. QOL was assessed using EORTC questionnaires.Results: Sixteen ELAPE (14 laparoscopic), 10 LAPE, and 10 OAPE were included. Demographics, tumour stage, and neoadjuvant therapy use were comparable. Operative time was higher with ELAPE than LAPE and OAPE (295, 207.5, and 157.5 min, respectively, p = 0.01). A porcine collagen perineal mesh was used in 9 patients undergoing ELAPE but in no LAPE or OAPE patients. No difference in 30-day complications, re-admission, or length of stay was noted. ELAPE and LAPE were associated with earlier removal of urinary catheter (p = 0.02), yet other enhanced recovery after surgery (ERAS) parameters were equivalent. All ELAPE resections were R0 with no positive CRM identified. One LAPE and 2 OAPE were R1 resections. Analysis revealed no deterioration in QOL with ELAPE, with equivalent global health status.Conclusions: The results of this study suggest that ELAPE is not associated with deterioration in short-term outcomes or QOL when compared with LAPE or OAPE
- …
