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排序方式: 共有3449条查询结果,搜索用时 11 毫秒
101.
Vladimir V.Novikov 《电子与封装》2004,4(4)
In spite of a long period of the development ofmicroelectronic components base, the problem of the creation of IC package design, providing minimal area losses in contrast with area of a chip, remains unsolved [1]Area losses can be described by the parameter P,which is equal to the ratio between the package area in plan and the chip area: 相似文献
102.
103.
This paper investigates data compression methods for time-of-flight (TOF) positron emission tomography (PET), which rebin the 3-D TOF measurements into a set of 2-D TOF data for a stack of transaxial slices. The goal of this work is to develop rebinning algorithms that are more accurate than the TOF single-slice-rebinning (TOF-SSRB) method proposed by Mullani in 1982. Two approaches are explored. The first one is based on a partial differential equation, which expresses a consistency condition for TOF-PET data with a Gaussian TOF profile. From this equation we derive an analytical rebinning algorithm, which is unbiased in the limit of continuous sampling. The second approach is discrete: each 2-D rebinned data sample is calculated as a linear combination of the 3-D TOF samples in the same axial plane parallel to the axis of the scanner. The coefficients of the linear combination are precomputed by optimizing a cost function which enforces both accuracy and good variance reduction, models the TOF profile, the axial PSF of the LORs, and the specific sampling scheme of the scanner. Measurements of a thorax phantom on a prototype TOF-PET scanner with a resolution of 550 ps show that the proposed discrete method improves the bias-variance trade-off and is a promising alternative to TOF-SSRB when data compression is required to achieve clinically acceptable reconstruction time. 相似文献
104.
José Vicente Calvano Antônio Carneiro de Mesquita Filho Vladimir Castro Alves Marcelo Soares Lubaszewski 《Microelectronics Journal》2002,33(10):823-834
This work presents a method for synthesizing testable continuous-time linear time-invariant electrical networks using 1st order blocks for the implementation of analog linear circuits. A functional-structural fault model for the block, and a fault dictionary are proposed together with a simple set of test vectors. The method allows, also, the fault grade evaluation for the modeled faults. The results obtained from the two application examples have shown the suitability of the approach as a design for test method for analog circuits. 相似文献
105.
Patsy V. Ramírez-González María Mercedes Zavala Arriaga Vladimir A. Escobar-Barrios 《Petroleum Science and Technology》2018,36(16):1242-1249
Interfacial tension and contact angle are two specific important parameters to take decisions for enhanced oil recovery, for instance, proper chemicals to use for surface tension reduction, expected wettability of solids, interaction between crude oil and rock. For this purpose, the article presents a method for easy calculation of the solid-liquid interfacial tension based on contact angle measurements applying Neumann's correlation and Young's equation. The main idea stands on the calculation of the rock parameters, like wettability, with known substances and extend these results to crude oils. It was possible, based on the results obtained, to establish a relationship between solid-liquid interfacial tension and contact angle for the crude oil – rock system, which can definitively be used for the calculation of interfacial tension of any other fluid spread out on the same kind of rock. A linear regression was obtained with an accuracy as good as R2 = 0.9989. Viscosity as a function of contact angle could also be obtained for the studied crude oils in the same kind of rock. 相似文献
106.
Rudolf Ahlswede Vladimir Blinovsky 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2007,53(2):526-533
We prove that the average error classical capacity C(W) of a classicalquantum arbitrarily varying channel (cq-AVC) W equals 0 or else the random code capacity C (Ahlswede's dichotomy). We also establish a necessary and sufficient condition for C(W)>0 相似文献
107.
Polyazines and Polyazomethines with Didodecylthiophene Units for Selective Dispersion of Semiconducting Single‐Walled Carbon Nanotubes 下载免费PDF全文
Widianta Gomulya Vladimir Derenskyi Erika Kozma Mariacecilia Pasini Maria Antonietta Loi 《Advanced functional materials》2015,25(36):5858-5864
Polymer wrapped single‐walled carbon nanotubes (SWNTs) have been demonstrated to be a very efficient technique to obtain high purity semiconducting SWNT solutions. However, the extraction yield of this technique is low compared to other techniques. Poly‐alkyl‐thiophenes have been reported to show higher extraction yield compare to polyfluorene derivatives. Here, the affinity for semiconducting SWNTs of two polymers with a backbone containing didodecylthiophene units interspersed with N atoms is reported. It is demonstrated that one of the polymers, namely, poly(2,5‐dimethylidynenitrilo‐3,4‐didodecylthienylene) (PAMDD), has very high semiconducting SWNT extraction yield compared to the poly(3,4‐didodecylthienylene)azine (PAZDD). The dissimilar wrapping efficiency of these two polymers for semiconducting SWNTs is attributed to the interplay between the affinity for the nitrogen atoms of the highly polarizable walls of SWNTs and the mechanical flexibility of the polymer backbones. Photoluminescence (PL) measurements demonstrate the presence of metallic tubes and SWNT bundles in the sample selected with PAZDD and higher purity of SWNT‐PAMDD samples. The high purity of the semiconducting SWNTs selected by PAMDD is further demonstrated by the high performance of the solution‐processed field‐effect transistors (FETs) fabricated using a blade coating technique, which exhibit hole mobilities up to 33.3 cm2 V?1 s?1 with on/off ratios of 106. 相似文献
108.
Vladimir V. Veremey Yury A. Tuchkin 《Journal of Infrared, Millimeter and Terahertz Waves》1997,18(4):909-938
An analysis of resonances of scattering from multi-element grating formed by a finite number of resonant elements is presented. It has been shown that gratings with three and more elements on its period can support the π-mode. The π-mode of a grating is characterized by the existence of the regions in the vicinity of the grating and along its period where the electromagnetic field has opposite phases. The existence and excitation of the π-mode in finite gratings with resonant cells formed by several scatterers having open cavities have been studied. The particular case of the grating with cells formed by three identical slotted cylinders has been considered in detail. An application of gratings which support the π-mode in electron-vacuum oscillators of millimeter waves for efficient deceleration of electrons and extracting energy from electron beam is discussed. 相似文献
109.
Grace G. D. Han Kun‐Hua Tu Farnaz Niroui Wenshuo Xu Si Zhou Xiaochen Wang Vladimir Bulović Caroline A. Ross Jamie H. Warner Jeffrey C. Grossman 《Advanced functional materials》2017,27(45)
Monolayer 2D MoS2 grown by chemical vapor deposition is nanopatterned into nanodots, nanorods, and hexagonal nanomesh using block copolymer (BCP) lithography. The detailed atomic structure and nanoscale geometry of the nanopatterned MoS2 show features down to 4 nm with nonfaceted etching profiles defined by the BCP mask. Atomic resolution annular dark field scanning transmission electron microscopy reveals the nanopatterned MoS2 has minimal large‐scale crystalline defects and enables the edge density to be measured for each nanoscale pattern geometry. Photoluminescence spectroscopy of nanodots, nanorods, and nanomesh areas shows strain‐dependent spectral shifts up to 15 nm, as well as reduction in the PL efficiency as the edge density increases. Raman spectroscopy shows mode stiffening, confirming the release of strain when it is nanopatterned by BCP lithography. These results show that small nanodots (≈19 nm) of MoS2 2D monolayers still exhibit strong direct band gap photoluminescence (PL), but have PL quenching compared to pristine material from the edge states. This information provides important insights into the structure–PL property correlations of sub‐20 nm MoS2 structures that have potential in future applications of 2D electronics, optoelectronics, and photonics. 相似文献
110.
Vladimir Dvorkin 《电子设计技术》2007,14(2):103-103
无论是测量还是使用流行的2.4GHz ISM(工业/科学/医疗)频带中工作的射频电路,无绳电话、Wi-Fi接入点、蓝牙设备、微波炉都能辐射出射频信号,导致不需要的干扰.频谱分析仪依然是检测和鉴别干扰源的首选仪器,但分析仪很贵、很庞大,并且有时不能立即使用. 相似文献