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1.
Tomerlin Andrew T. Edmonson William W. 《Multidimensional Systems and Signal Processing》2002,13(3):333-340
Consider the class of d-dimensional causal filters characterized by a d-variate rational function
analytic on the polydisk
. The BIBO stability of such filters has been the subject of much research over the past two decades. In this paper we analyze the BIBO stability of such functions and prove necessary and sufficient conditions for BIBO stability of a d-dimensional filter. In particular, we prove if a d-variate filter H(z) analytic on
has a Fourier expansion that converges uniformly on the closure of
, then H(z) is BIBO stable. This result proves a long standing conjecture set forth by Bose in [3]. 相似文献
2.
The ability of a parallel algorithm to make efficient use of increasing computational resources is known as its scalability. In this paper, we develop four parallel algorithms for the 2-dimensional Discrete Wavelet Transform algorithm (2-D DWT), and derive their scalability properties on Mesh and Hypercube interconnection networks. We consider two versions of the 2-D DWT algorithm, known as the Standard (S) and Non-standard (NS) forms, mapped onto P processors under two data partitioning schemes, namely checkerboard (CP) and stripped (SP) partitioning. The two checkerboard partitioned algorithms
(Non-standard form, NS-CP), and as
(Standard form, S-CP); while on the store-and-forward-routed (SF-routed) Mesh and Hypercube they are scalable as
(NS-CP), and as
(S-CP), respectively, where M
2 is the number of elements in the input matrix, and (0,1) is a parameter relating M to the number of desired octaves J as
. On the CT-routed Hypercube, scalability of the NS-form algorithms shows similar behavior as on the CT-routed Mesh. The Standard form algorithm with stripped partitioning (S-SP) is scalable on the CT-routed Hypercube as M
2 = (P
2), and it is unscalable on the CT-routed Mesh. Although asymptotically the stripped partitioned algorithm S-SP on the CT-routed Hypercube would appear to be inferior to its checkerboard counterpart S-CP, detailed analysis based on the proportionality constants of the isoefficiency function shows that S-SP is actually more efficient than S-CP over a realistic range of machine and problem sizes. A milder form of this result holds on the CT- and SF-routed Mesh, where S-SP would, asymptotically, appear to be altogether unscalable. 相似文献
3.
Let
相似文献
4.
This paper considers the problem of constructing feedback stabilizing controllers for the wave operator on
n (more generally AR systems determined by a hyperbolic operator). In order to accomplish this, it must first clarify the notion of an input-output structure on a distributed system, as well as what it means to interconnect two such systems. Both these notions are shown to be consequences of a structure which generalizes the standard causal structure of lumped systems determined by the flow of time. Given this apparatus, the paper then constructs feedback controllers which stabilize the wave equation along directions given by a proper cone in
n. 相似文献
5.
This paper studies the notions of time-autonomy and (exact) time-controllability of behaviours with respect to a certain mild space, which while being not too general, encompasses natural partial differential equation solutions and excludes certain pathological ones. We give an algebraic characterization of the property of time-autonomy and also give necessary and sufficient conditions for the time-controllability of behaviours with respect to the space of distributions on
that are tempered in the spatial direction. 相似文献
6.
Interfacial reactions of Y and Er thin films on both (111)Si and (001)Si have been studied by transmission electron microscopy
(TEM). Epitaxial rare-earth (RE) silicide films were grown on (111)Si. Planar defects, identified to be stacking faults on
planes with 1/6
displacement vectors, were formed as a result of the coalescence of epitaxial silicide islands. Double-domain epitaxy was
found to form in RE silicides on (001)Si samples resulting from a large lattice mismatch along one direction and symmetry
conditions at the silicide/(001)Si interfaces. The orientation relationships are [0001]RESi2−x//
Si,
RESi2−x//(001)Si and [0001]RESi2−x/
Si,
RESi2−x//(001)Si. The density of staking faults in (111) samples and the domain size in (001) samples were found to decrease and
increase with annealing temperature, respectively. 相似文献
7.
In this paper, we investigate the problem of approximating a given (not necessarily bandlimited) signal, x(t), by a (bandlimited) interpolation or sampling series of the form:
8.
Hao Lee Weidong Yang Peter C. Sercel A. G. Norman 《Journal of Electronic Materials》1999,28(5):481-485
We have determined the shape of InAs quantum dots using reflection high energy electron diffraction. Our results indicate
that self-assembled InAs islands possess a pyramidal shape with {136} bounding facets. This shape is characterized by C2v
symmetry and a parallelogram base, which is elongated along the
direction. Cross-sectional transmission electron microscopy images taken along the [110] and
directions as well as atomic force microscopy images strongly support the {136} shape. Furthermore, polarization-resolved
photoluminescence spectra show strong in-plane anisotropy, with emission predominantly polarized along the
direction, consistent with the proposed quantum dot shape. 相似文献
9.
In this paper we investigate new Fourier series with respect to orthonormal families of directed cycles
, which occur in the graph of a recurrent stochastic matrixP. Specifically, it is proved thatP may be approximated in a suitable Hilbert space by the Fourier series
. This approach provides a proof in terms of Hilbert space of the cycle decomposition formula for finite stochastic matricesP. 相似文献
10.
A 900 MHz low-power CMOS bandpassamplifier suitable for the applications of RFfront-end in wireless communication receiversis proposed and analyzed. In this design, thetemperature compensation circuit is used tostabilize the amplifier gain so that theoverall amplifier has a good temperaturestability. Moreover, the compact tunablepositive-feedback circuit is connected to theintegrated spiral inductor to generate thenegative resistance and enhance its
value. The simple diode varactor circuit isadopted for center-frequency tuning. These twoimproved circuits can reduce the powerdissipation of the amplifier. An experimentalchip fabricated by 0.5 mdouble-poly-double-metal CMOS technologyoccupies a chip area of
; chip area. The measuredresults have verified the performance of thefabricated CMOS bandpass amplifier. Under a2-V supply voltage, the measured quality factoris tunable between 4.5 and 50 and the tunablefrequency range is between 845 MHz and 915 MHz. At
, the measured
is 20 dB whereas thenoise figure is 5.2 dB in the passband. Thegain variation is less than 4 dB in the rangeof 0–80°C. The dc powerdissipation is 35 mW. Suitable amplifier gain,low power dissipation, and good temperaturestability make the proposed bandpass amplifierquite feasible in RF front-endapplications. 相似文献
11.
Jyh-Haur Hwang Sun-Yuan Tsay Chyi Hwang 《Multidimensional Systems and Signal Processing》1999,10(2):137-160
An algorithm is presented to compute the variance of the output of a two-dimensional (2-D) stable auto-regressive moving-average (ARMA) process driven by a white noise bi-sequence with unity variance. Actually, the algorithm is dedicated to the evaluation of a complex integral of the form
, where
and G(z1,z2) = B(z1, z2) / A(z1, z2) is stable (z1,z2)-transferfunction. Like other existing methods, the proposed algorithmis based on the partial-fraction decomposition G(z1,z2)G(z
1
-1
, z
2
-1
) = X(z1, z1) / A(z1,z2)+ X(z
1
-1
, z
2
-1
) / A(z
1
-1
, z
2
-1
). However,the general and systematic partial-fraction decomposition schemeof Gorecki and Popek [1] is extended to determine X(z1,z2).The key to the extension is that of bilinearly transforming thediscrete (z1, z2)-transfer function G(z1,z2)into a mixed continuous-discrete (s1, z2)-transferfunction
. As a result, the partial-fraction decomposition involves only efficient DFT computations for the inversion of a matrix polynomial, and the value of I is finally determined by the residue method with finding the roots of a 1-D polynomial. The algorithm is very easy to implement and it can be extended to the covariance computation for two 2-D ARMA processes. 相似文献
12.
A novel figure of merit to describe the bandwidth power efficiency of CMOS transconductors—
is proposed and optimized for cross-coupled differential pair transconductor structures. The optimization is done in two different ways: univariable unconstrained and multivariable constrained. It is revealed that not only dc biases but also ac input phases can affect the bandwidth power efficiency of the transconductor. The bias voltages which can lead to best
ratio at different ac phase combinations are obtained and presented in the article. HSPICE simulations are conducted to verify the theoretical predictions. On the basis of the cross-coupled differential pair transconductor, a biquadratic transconductor-C filter configuration is implemented. The frequency vs. power characteristic of the filter is studied for both optimally- and non-optimally-biased transconductor. It is shown that the
optimization of the transconductor structure can result in performance improvement of the transconductor-C filter. The deviation of the optimal bias condition between the transconductor alone and the transconductor-C filter due to the inclusion of peripheray circuitries in the filter is discussed in the article. 相似文献
13.
Orientation dependent etching of photolithographically patterned
GaP was investigated using solutions of HCl:CH3COOH:H2O2. The pattern was prepared using standard ultraviolet lithography and was a two-dimensional grid with an 18 μm repeat, consisting
of 15 μm squares separated by 3 μm spaces. The mask sides were aligned along the
and
directions. Under appropriate etching conditions, high quality arrays of pyramids were prepared. These pyramids were defined
by
,
and
facets. It was shown that the etching process depended on the degree of solution aging after initial mixing. For a freshly
prepared solution, the etching rate showed an inverse dependence on time. For short etching times (below 5 min), an intermediate
etching profile was followed, while for long times (greater than 5 min) etching was kinetically controlled. We demonstrated
that controlled etching at extremely low rates (0.1–0.5 μm/min) is feasible with this new approach. 相似文献
14.
Constant-round zero-knowledge proof systems for every language in
are presented, assuming the existence of a collection of claw-free functions. In particular, it follows that such proof systems exist assuming the intractability of either the Discrete Logarithm Problem or the Factoring Problem for Blum integers. 相似文献
15.
Bruce D. Calvert 《Circuits, Systems, and Signal Processing》1999,18(3):241-267
We study solutions of the linear system in a saturated mode
16.
Seoyong Ha Noel T. Nuhfer Gregory S. Rohrer Marc de Graef Marek Skowronski 《Journal of Electronic Materials》2000,29(7):L5-L8
Transmission electron microscopy (TEM) and KOH etching have been used to study the dislocation structure of 4H SiC wafers
grown by physical vapor transport. A new type of threading dislocation arrays was observed. Rows of etch pits corresponding
to dislocation arrays were observed in vicinity of micropipes, misoriented grains and polytypic inclusions at the periphery
of the boules and extended along the
directions. Plan view conventional and high resolution TEM showed that the arrays consisted of dislocations threading along
the c-axis with Burgers vectors having edge components of the a/3
type. The Burgers vectors were parallel to the corresponding arrays. The dislocation arrays were interpreted as slip bands
formed by dislocation glide in the prismatic slip system
of hexagonal SiC during post-growth cooling. 相似文献
17.
A Fully Integrated, Low Noise and Low Power BiCMOS Front-end Readout System for Capacitive Detectors 总被引:1,自引:0,他引:1
Chaoying-Christine Guo Philippe Schmitt Grzegorz Deptuch Yongcai-Yann Hu 《Analog Integrated Circuits and Signal Processing》2001,28(3):211-223
Bipolar transistors are interesting for low noise front-end readout systems when high speed and low power consumption are required. This paper presents a fully integrated, low noise front-end design for the future Large Hadron Collider (LHC) experiments using the radiation hard SOI BiCMOS process. In the present prototype, the input-referred Equivalent Noise Charge (ENC) of 990 electrons (rms) for 12 pF detector capacitance with a shaping time of 25 ns and power consumption of 1.4 mW/channel has been measured. The gain of this front-end is 90 mV/MIP (Minimum Ionisation Particle: 1
fC) with non-linearity of less than 3% and linear input dynamic range is
MIP. These results are obtained at room temperature and before irradiation. The measurements after irradiations by high intensity pion beam with an integrated flux of
pions/cm2 are also presented in this paper. 相似文献
18.
CORDIC-based algorithms to compute cos
and
are proposed. The implementation requires a standard CORDIC module plus a module to compute the direction of rotation, this being the same hardware required for the extended CORDIC vectoring, recently proposed by the authors [T. Lang and E. Antelo, IEEE Transactions on Computers, vol. 47, no. 7, 1998, pp. 736–749.]. Although these functions can be obtained as a special case of this extended vectoring, the specific algorithm we propose here presents two significant improvements: (1) it uses the same datapath width as the standard CORDIC, even when t has 2n bits (to achieve a granularity of 2–n for the whole range). In contrast, the extended vectoring unit requires about 2n bits. (2) no repetitions of iterations are needed (the extended vectoring needs some repetitions). The proposed algorithm is compatible with the extended vectoring and, in contrast with previous implementations, the number of iterations and the delay of each iteration are the same as for the conventional CORDIC algorithm. 相似文献
19.
Charalampos Kapnistis Konstantinos Misiakos Nikos Haralabidis 《Analog Integrated Circuits and Signal Processing》2001,27(1-2):39-49
A charge sensitive readout chain has been designed and fabricated in acommercially available 0.8 m CMOS technology. The readout chain is optimizedfor pixel detectors measuring soft X-ray energies up to 20 KeV. In the first modean analog signal proportional to input charge is generated and processed in realtime. In the second mode a peak-and-hold operation is enabled and therelevant signal is processed in later time. This dual mode of operation iscontrolled by an external digital signal. The readout chain consists of a chargeamplifier, a shaper, an operational amplifier which can either operate as avoltage amplifier or a peak detector and an output buffer. Its area is
. The gain at the shaper output is 378 mv/fC, theENC is 16
rms at 160 nsec shaping time. The overall gainis 557 mV/fC, the ENC is
rms with 240 nsec peaking timeand 1.4 sec recovery time. The overall power dissipation is 1.5 mWatt with aload capacitance of 25 pF. 相似文献
20.
Feng Wu Shai Zamir Boris Meyler Joseph Salzman Yuval Golan 《Journal of Electronic Materials》2003,32(1):23-28
Transmission electron microscopy (TEM), atomic force microscopy (AFM), and photoluminescence (PL) spectroscopy were used in
order to study the microstructure and optical properties of GaN films grown by metal-organic chemical vapor deposition (MOCVD)
on c-plane sapphire by lateral confined epitaxy (LCE). In this method, the substrate is etched prior to growth to form uniform
mesas separated by trenches for laterally restricting growth area. As previously observed for LCE GaN on Si(111), the density
of threading dislocations was significantly reduced in the areas close to the edge of mesas due to the lateral propagation
of the dislocations. Hence, the overall material quality improves with decreasing mesa size, which is consistent with the
observed increase in photoluminescence band edge peak intensity. Electron diffraction indicated ∼1° rotation about the [
] axis between the mesa and trench material, which was also observed in the image contrast of these two regions with g=
. Additionally, LCE samples prepared in [
] and [
] cross sections were used for comparing the growth rates in these two perpendicular directions. As theoretically expected,
growth in the [
] direction appears to proceed considerably faster than that in the [% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn%
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