17,903 research outputs found

    Behavioral modeling of digital IC input and output ports

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    This paper addresses the development of accurate and efficient behavioral models of digital integrated circuit input and output ports for signal integrity simulations and timing analyses. The modeling process is described and applied to the characterization of actual device

    Behavioral Modeling of IC Ports Including Temperature Effects

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    The development of temperature-dependent macromodels for digital IC ports is addressed. The proposed modeling approach is based on the theory of discrete-time parametric models and allows one to estimate the model parameters from voltage and current waveforms observed at the ports and to implement the model as a SPICE subcircuit. The proposed technique is validated by applying it to commercial devices described by detailed transistor-level models. The obtained models perform at a good accuracy level and are more efficient than the original transistor-level models

    Renewable build-up pathways for the US: Generation costs are not system costs

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    The transition to a future electricity system based primarily on wind and solar PV is examined for all regions in the contiguous US. We present optimized pathways for the build-up of wind and solar power for least backup energy needs as well as for least cost obtained with a simplified, lightweight model based on long-term high resolution weather-determined generation data. In the absence of storage, the pathway which achieves the best match of generation and load, thus resulting in the least backup energy requirements, generally favors a combination of both technologies, with a wind/solar PV energy mix of about 80/20 in a fully renewable scenario. The least cost development is seen to start with 100% of the technology with the lowest average generation costs first, but with increasing renewable installations, economically unfavorable excess generation pushes it toward the minimal backup pathway. Surplus generation and the entailed costs can be reduced significantly by combining wind and solar power, and/or absorbing excess generation, for example with storage or transmission, or by coupling the electricity system to other energy sectors.Comment: 11 pages, 6 figure

    Macromodeling strategy for digital devices and interconnects

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    International audienceThis paper proposes a macromodeling approach for the simulation of digital interconnected systems. Such an approach is based on a set of macromodels describing IC ports, IC packages and multiconductor interconnect structures in standard circuit simulators, like SPICE. We illustrate the features of the macromodels and we demonstrate the proposed approach on a realistic simulation problem

    Make the Most Out of Your Net: Alternating Between Canonical and Hard Datasets for Improved Image Demosaicing

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    Image demosaicing is an important step in the image processing pipeline for digital cameras, and it is one of the many tasks within the field of image restoration. A well-known characteristic of natural images is that most patches are smooth, while high-content patches like textures or repetitive patterns are much rarer, which results in a long-tailed distribution. This distribution can create an inductive bias when training machine learning algorithms for image restoration tasks and for image demosaicing in particular. There have been many different approaches to address this challenge, such as utilizing specific losses or designing special network architectures. What makes our work is unique in that it tackles the problem from a training protocol perspective. Our proposed training regime consists of two key steps. The first step is a data-mining stage where sub-categories are created and then refined through an elimination process to only retain the most helpful sub-categories. The second step is a cyclic training process where the neural network is trained on both the mined sub-categories and the original dataset. We have conducted various experiments to demonstrate the effectiveness of our training method for the image demosaicing task. Our results show that this method outperforms standard training across a range of architecture sizes and types, including CNNs and Transformers. Moreover, we are able to achieve state-of-the-art results with a significantly smaller neural network, compared to previous state-of-the-art methods

    Effects of a saponin fraction extracted from Trigonella foenum-graecum L. and two commercially available saponins on sex ratio and gonad histology of Nile tilapa fry, Oreochromis niloticus (L.)

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    Over three million tonnes (t) of tilapia, mostly Nile tilapia (Oreochromis niloticus, L.), are produced annually making it the second most abundantly produced freshwater fish (FAO, 2010). Tilapia are mouthbreeders that often produce stunted populations under pond conditions; one means of prevention is to produce all-male fish with the additional advantage that males usually grow faster than females. All-male populations can be achieved by supplementing feed with androgens such as 17-α-Methyltestosterone (MT) during days 10–25 post-hatch (Pandian and Sheela, 1995). However, MT is considered to be carcinogenic (Velazquez and Alter, 2004), and Hulak et al. (2008) also showed that effluents of systems in which carp were fed diets containing MT caused masculinization of female fish. Furthermore, in aquaculture the application of hormones to fish destined for human consumption is prohibited in the European Union under directive 96/22/EC, article 5, which also prohibits import of animal products produced with hormones. Kwon et al. (2000) showed that Fadrozole, a non-steroidal compound, caused masculinization in tilapia by inhibiting aromatase, which is the enzyme responsible for the conversion of endogenous androgens to estrogens. Steinbronn et al. (2004) were able to show that a dose of 2000 ppm Quillaja saponins (Sigma S-2149) inhibited reproduction of tilapia after dietary application for 32 days to first-feeding fry, suggesting saponins as a possible alternative to MT. These secondary plant compounds consist of either a steroid or triterpenoid basic structure (aglycone or sapogenin) plus one or more sugar side chains (Francis et al., 2002a). In a previous experiment a saponin fraction from the soapbark tree (Quillaja saponaria M.) inhibited aromatase in vitro (Golan et al., 2008). The fenugreek plant (Trigonella foenum-graecum L), widely cultivated in the Middle East and Asia, also has a high saponin content. The experiment was therefore conducted to test whether saponin fractions from Q. saponaria and from T. foenum-graecum were able to influence the sex ratio and gonad histology of Nile tilapia

    Origin of Unexpected Low Energy Structure in Photoelectron Spectra Induced by Mid-Infrared Strong Laser Fields

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    Using a semiclassical model which incorporates tunneling and Coulomb field effects, the origin of the unexpected low-energy structure (LES) in above-threshold ionization spectrum observed in recent experiments [C. I. Blaga et al., Nature Phys. {\bf 5}, 335 (2009) and W. Quanet al., Phys. Rev. Lett. {\bf 103}, 093001 (2009)] is identified. We show that the LES arises due to an interplay between multiple forward scattering of an ionized electron and the electron momentum disturbance by the Coulomb field immediately after the ionization. The multiple forward scattering is mainly responsible for the appearance of LES, while the initial disturbance mainly determines the position of the LES peaks. The scaling laws for the LES parameters, such as the contrast ratio and the maximal energy, versus the laser intensity and wavelength are deduced

    Relativistic ionization-rescattering with tailored laser pulses

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    The interaction of relativistically strong tailored laser pulses with an atomic system is considered. Due to a special tailoring of the laser pulse, the suppression of the relativistic drift of the ionized electron and a dramatic enhancement of the rescattering probability is shown to be achievable. The high harmonic generation rate in the relativistic regime is calculated and shown to be increased by several orders of magnitude compared to the case of conventional laser pulses. The energies of the revisiting electron at the atomic core can approach the MeV domain, thus rendering hard x-ray harmonics and nuclear reactions with single atoms feasible
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