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排序方式: 共有576条查询结果,搜索用时 593 毫秒
121.
In this study, we present two new grounded capacitance multiplier circuits based on a negative-type second-generation current conveyor (CCII-) and an inverting second-generation current conveyor (ICCII). The first proposed circuit consists of one CCII- and a voltage follower (VF) employing two NMOS transistors while the second proposed circuit is composed of an ICCII and an inverting voltage follower (IVF) including two NMOS transistors. Each circuit contains two resistors, and single grounded capacitor, which is attractive for integrated circuit realization. No active and passive component matching conditions are required for the realization of the proposed capacitance multiplier circuits. The simulation results are included to confirm the theory. 相似文献
122.
123.
124.
The mechanisms governing the activation of dislocation sources in aluminum at different strain rates
This article examines the time to activate Frank–Read sources in response to macroscopic strain rates ranging from 101 s−1 to 1010 s−1 in aluminium under athermal conditions. We develop analytical models of the bowing of a pinned dislocation segment as well as numerical simulations of three dimensional dislocation dynamics. We find that the strain rate has a direct influence on both the activation time and the source strength of Frank–Read sources at strain rates up to 106 s−1, and the source strength increases in almost direct proportion to the strain rate. This contributes to the increase in the yield stress of materials at these strain rates. Above 106 s−1, the speed of the bowing segments reaches values that exceed the domain of validity of the linear viscous drag law, and the drag law is modified to account for inertial effects on the motion of the dislocation. As a result the activation times of Frank–Read sources reach a finite limit at strain rates greater than 108 s−1, suggesting that Frank–Read sources are unable to operate before homogeneous nucleation relaxes elastic stresses at the higher strain rates of shock loading. Elastodynamic calculations are carried out to compare the contributions of Frank–Read sources and homogeneous nucleation of dislocations to plastic relaxation. We find that at strain rates of 5×107 s−1 homogeneous nucleation becomes the dominant generation mechanism. 相似文献
125.
Thomas Henneron Stéphane Clénet Patrick Dular Francis Piriou 《Journal of Computational and Applied Mathematics》2008
The consideration of electromagnetic field sources in potential formulations necessitates the definition of source fields. Such source fields are first defined for both volume and boundary constraints in static electromagnetic models. Then, automatic procedures are proposed to conveniently and efficiently characterize discrete source fields, with regard to their use in finite element formulations, their supports, their direct expression requiring no pre-computation, and their associated constraints. Two application examples are proposed to illustrate the approach. 相似文献
126.
Cristina Silvano Giovanni Agosta Gianluca Palermo 《Design Automation for Embedded Systems》2007,11(1):1-23
The hardware/software co-exploration is a critical phase for a broad range of embedded platforms based on the System-On-Chip
approach. Traditionally, the compilation and the architectural design sub-spaces have been explored independently. Only recently,
some approaches have analyzed the problem of the concurrent exploration of the compilation/architecture sub-spaces. This paper
proposes a framework to support the co-exploration phase of the design space composed of architectural parameters and source
program transformations. The objective space is multi-dimensional, including conflicting objectives such as energy and delay.
In the proposed framework, heuristic co-exploration techniques based on Pareto Simulated Annealing (PSA) have been used to
efficiently explore the architecture/compiler co-design space. A first result of this paper consists of showing how the architecture/compiler
co-exploration can be more effective than a traditional two-phase exploration. Since the co-exploration space is quite large,
to speed up the co-exploration phase by several orders of magnitude over simulation-based approaches, a methodology based
on analytical models has been introduced in the co-exploration framework. The goal of analytical models is to quickly evaluate
energy/delay metrics at the systems level, while maintaining accuracy with respect to simulation-based co-exploration. The
proposed co-exploration framework has been applied to a parameterized SoC superscalar architecture during the execution of
a selected set of multimedia applications. 相似文献
127.
Let G=(V,E) be a simple undirected graph with a set V of vertices and a set E of edges. Each vertex v∈V has an integer valued demand d(v)?0. The source location problem with vertex-connectivity requirements in a given graph G asks to find a set S of vertices with the minimum cardinality such that there are at least d(v) vertex-disjoint paths between S and each vertex v∈V-S. In this paper, we show that the problem with d(v)?3, v∈V can be solved in linear time. Moreover, we show that in the case where d(v)?4 for some vertex v∈V, the problem is NP-hard. 相似文献
128.
Diana White Nicholas Carruth Joshua Eastes Dominic Klyve Daniel Otero Nicholas A. Scoville 《International Journal of Mathematical Education in Science & Technology》2019,50(7):987-998
ABSTRACTThis study investigates changes in instructor teaching tendencies, instructor’s perception of impact on student learning and dispositions, and methods of implementation of Primary Source Projects (PSPs). PSPs are curricular modules designed to teach core mathematical topics from primary historical sources rather than from standard textbooks. In essence, they are a form of inquiry-based learning that incorporates the history of mathematics through original source texts. We provide an overview of results from two semesters of implementation reports and surveys administered at the beginning and end of the semester by instructors who implemented PSPs in their undergraduate mathematics classes. 相似文献
129.
Daniel J. G. Johnson Ian D. Jenkins Cohan Huxley Mark J. Coster Kah Yean Lum Jonathan M. White Vicky M. Avery Rohan A. Davis 《Molecules (Basel, Switzerland)》2021,26(9)
A radical approach to late-stage functionalization using photoredox and Diversinate™ chemistry on the Open Source Malaria (OSM) triazolopyrazine scaffold (Series 4) resulted in the synthesis of 12 new analogues, which were characterized by NMR, UV, and MS data analysis. The structures of four triazolopyrazines were confirmed by X-ray crystal structure analysis. Several minor and unexpected side products were generated during these studies, including two resulting from a possible disproportionation reaction. All compounds were tested for their ability to inhibit the growth of the malaria parasite Plasmodium falciparum (3D7 and Dd2 strains) and for cytotoxicity against a human embryonic kidney (HEK293) cell line. Moderate antimalarial activity was observed for some of the compounds, with IC50 values ranging from 0.3 to >20 µM; none of the compounds displayed any toxicity against HEK293 at 80 µM. 相似文献
130.
In this paper a wideband flipped voltage follower (FVF) with low output impedance at high frequency has been proposed. Inductive-peaking-based bandwidth extension technique is employed in the FVF cell. The small signal high-frequency analysis of both conventional and proposed FVF has been done. It is shown in analytical derivation of the proposed FVF that by adding an inductive element in the feedback path, the bandwidth is enhanced. Simulation results show that bandwidth extension ratio (BWER) of proposed FVF is about 2.00, without extra dc power dissipation. A wideband low voltage current mirror has been developed by using proposed FVF in place of conventional FVF and by doing so, BWER of 2.98 has been achieved. The performances of circuits are verified in TSMC 0.18 μm CMOS, BSIM3 and Level 49 technology with 1.5 V power supply and by using Spectre simulator of Cadence. 相似文献