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1.
The synthesis of the organometallic d2 [Cp*W(dmit)2]1– complex (where Cp* is pentamethylcyclopentadienyl and dmit is 1,3‐dithiole‐2‐thione‐4,5‐dithiolate), and its oxidation to the paramagnetic d1 [Cp*W(dmit)2] species, is described and their X‐ray crystal structures given. Geometrical evolutions upon oxidation, characterized by a variable folding of the WS2C2 metallacycles along the S–S hinge, are rationalized by density functional theory (DFT) calculations and by comparison with the molybdenum analogs; as is also the evolution in the UV‐vis‐NIR absorption spectra. In solution, only the d1 complexes exhibit positive optical density variations in transitory nanosecond spectroscopy after 10 ns laser pulses. A weak optical limiting effect was observed on these d1 species, stronger in the W than in the Mo complex. In the solid state, the interacting, paramagnetic [Cp*W(dmit)2] species (θCurie–Weiss = –20 K) orders antiferromagnetically below TNéel = 4.5 K with a spin‐flop field, BSF(W) of 8000 G. Compared with the molybdenum analog, the weaker θCurie–Weiss(W) and TNéel(W) values, and larger BSF(W) values reflect weaker intermolecular interactions due to a decreased spin density on the dithiolene ligands and stronger spin–orbit coupling with the W atom, as confirmed by DFT calculations on the d2 and d1 Mo and W complexes.  相似文献   

2.
meso‐Tetrakis{4‐[2‐(trimethylsilyl)ethynyl]phenyl}porphyrin [TPP(4‐CCTMS)_H2] and its complexes with ZnII, NiII, GaIII, InIII, and SnIV were synthesized and characterized. Their nonlinear optical transmission characteristics were determined using a 532 nm, 5 ns pulsed laser at a repetition rate of 20 Hz. Stronger nonlinear absorption was obtained with the zinc derivative, ZnIImeso‐tetrakis{4‐[2‐(trimethylsilyl)ethynyl]phenyl}porphyrin (TPP(4‐CCTMS)_Zn), than with the standard analogues, ZnIImeso‐tetraphenylporphyrin (TPP_Zn), and ZnIImeso‐tetratolyl‐porphyrin (TTP_Zn), indicating that the excited‐state absorption can be influenced via fine molecular modification on the para‐position of the meso‐phenyl rings, without changing the ground‐state absorption. The nonlinear optical response can be further enhanced via insertion of closed‐shell metal ions. In particular, InIIICl‐meso‐tetrakis{4‐[2‐(trimethylsilyl)ethynyl]phenyl}porphyrin (TPP(4‐CCTMS)_InCl), exhibited a larger change in transmission with increasing energy than C60 and a comparable change to the state‐of‐the‐art phthalocyanine dye, chloro(tetra(tert‐butyl)phthalocyanato)indium(III) (Pc(t‐Bu)_InCl).  相似文献   

3.
Sb2Te3 and Bi2Te3 thin films were grown on SiO2 and BaF2 substrates at room temperature using molecular beam epitaxy. Metallic layers with thicknesses of 0.2?nm were alternately deposited at room temperature, and the films were subsequently annealed at 250°C for 2?h. x-Ray diffraction and energy-filtered transmission electron microscopy (TEM) combined with high-accuracy energy-dispersive x-ray spectrometry revealed stoichiometric films, grain sizes of less than 500?nm, and a texture. High-quality in-plane thermoelectric properties were obtained for Sb2Te3 films at room temperature, i.e., low charge carrier density (2.6?×?1019?cm?3), large thermopower (130???V?K?1), large charge carrier mobility (402?cm2?V?1?s?1), and resulting large power factor (29???W?cm?1?K?2). Bi2Te3 films also showed low charge carrier density (2.7?×?1019?cm?3), moderate thermopower (?153???V?K?1), but very low charge carrier mobility (80?cm2?V?1?s?1), yielding low power factor (8???W?cm?1?K?2). The low mobilities were attributed to Bi-rich grain boundary phases identified by analytical energy-filtered TEM.  相似文献   

4.
We report the synthesis and organic light‐emitting devices (OLEDs) made from a series of 1‐phenyl‐ and 3‐phenylisoquinolinyliridium complexes in which the phenyl group is linked to the C1 and C3 carbons of isoquinoline, respectively. These linkage isomers show distinct differences in their photophysical and electroluminescence (EL) properties, including the magnitude of phosphorescent lifetimes and photoluminescence (PL) and EL emission wavelengths, as well as the phenomenon of triplet–triplet (T–T) annihilation. Complexes of these two families show a strong absorption band in the region 440–490 nm assignable to spin‐forbidden 3MLCT (metal–ligand charge‐transfer) bands. The extinction coefficients of these bands are similar to those of spin‐allowed 1MLCT bands, indicative of an anomalously strong spin–orbital coupling. Upon excitation, 1‐phenylisoquinolinyliridium complexes exhibit a single phosphorescent emission band in the red region (595–631 nm). All of these red phosphors show outstanding EL performance with negligible T–T annihilation because of short phosphorescent lifetimes (1.04–2.46 μs in CH2Cl2) and good emission quantum yields. One representative, [Ir(5‐f‐1piq)2(acac)] (acac = acetylacetonate) ( 3 ) (5‐f‐1piqH = 5‐fluoro‐1‐phenylisoquinoline), is not only the brightest at low voltages (1883 cd m–2 at 7.1 V; 8320 cd m–2 at 9.0 V) but also shows a ηext value of. 6.50 % at high current (J = 400 mA cm–2). The maximum brightness is 38 218 cd m–2 (x = 0.68, y = 0.31) with the full width at half maximum (FWHM) only 50 nm at 8 V. In contrast, 3‐phenylisoquinolinyliridium complexes show phosphorescent emissions in the yellow region (534–562 nm) but with a long phosphorescent lifetime (3.90–15.6 μs in CH2Cl2). Most of these yellow phosphors suffer T–T annihilation in the EL performance. The exception is [Ir(3‐piq)2(acac)] ( 5 ) (3‐piqH = 3‐phenylisoquinoline), which has a relatively short lifetime 3.90 μs in CH2Cl2. Complex 5 achieves an external efficiency (ηext) value of 5.27 % at J = 20 mA cm–2 and maintains a ηext value of 3.58 at J = 400 mA cm–2 with a maximum brightness of 65 448 cd m–2 (x = 0.49, y = 0.51).  相似文献   

5.
Cationic Au4Ag2 heterohexanuclear aromatic acetylides cluster complexes supported by bis(2‐diphenylphosphinoethyl)phenylphosphine (dpep) are prepared. The Au4Ag2 cluster structure originating from the combination of one anionic [Au(C≡CR)2]? with one cationic [Au3Ag2(dpep)2(C≡CR)2]3+ through the formation of Ag?acetylide η2‐bonds is highly stabilized by Au–Ag and Au–Au contacts. The Au4Ag2 alkynyl cluster complexes are moderately phosphorescent in the fluid CH2Cl2 solution, but exhibit highly intense phosphorescent emission in solid state and film. As revealed by theoretical computational studies, the phosphorescence is ascribable to significant 3[π (aromatic acetylide) → s/p (Au)] 3LMCT parentage with a noticeable Au4Ag2 cluster centered 3[d → s/p] triplet state. Taking advantage of mCP and OXD‐7 as a mixed host with 20 wt% dopant of phosphorescent Au4Ag2 cluster complex in the emitting layer, solution‐processed organic light‐emitting diodes (OLEDs) exhibit highly efficient electrophosphorescence with the maximum current, power, and external quantum efficiencies of 24.1 cd A?1, 11.6 lm W?1, and 7.0%, respectively. Introducing copper(I) thiocyanate (CuSCN) as a hole‐transporting layer onto the PEDOT:PSS hole‐injecting layer through the orthogonal solution process induces an obvious improvement of the device performance with lower turn‐on voltage and higher electroluminescent efficiency.  相似文献   

6.
Precious metal intermetallic nanoclusters (IMNCs) are promising nanocatalysts for practical industrial applications. However, to date, the preparation of these nanoclusters has been restricted to harsh conditions, and only succeeds for a limited number of elements. This study developed a simple and efficient strategy that enables the synthesis of supported IMNCs under ambient conditions via inorganometallic coordination chemistry, specifically, by donating the Cl? ligand, a noble metal chloride (MClab?) forms a heterobimetallic ion (MxFeyClzn?) with the coordination‐unsaturated FeCl3. Upon reduction, the ordered heterobimetallic ions are simultaneously transformed into IMNCs and embedded into γ‐Fe2O3 nanosheets, which form from excess FeCl3. In addition to providing convincing spectral evidence for the structure of the heterobimetallic ions, magnetic measurements, atomic‐resolution electron microscopy, X‐ray absorption spectroscopy, and Fourier transform infrared spectroscopy of chemisorbed CO collectively confirm the successful preparation of the L10‐phased Pd3Fe IMNCs. Furthermore, this versatile method can be extended to synthesize other IMNCs, such as AuFe and PtFe, and seems to be applicable to IrFe, RhFe, RuFe, and MCo. When utilized as a heterogeneous catalyst in a Heck coupling reaction, the prepared Pd3Fe IMNCs display satisfactory activity and stability, highlighting their potential applications as advantageous catalysts.  相似文献   

7.
Thirty-nine new submillimetre laser lines in CH2F2 and twelve in CD2Cl2 have been obtained in a Fabry-Perot FIR resonator by optically pumping with a CW12C18O2 laser. The wavelength range obtained for CH2F2 is 126μm to 1091μm and for CD2Cl2 212μm to 774μm. The wavelength measurements are accurate to within 5.10?3. The relative polarisations of the pump laser and the FIR laser output were also determined. Tentative assignments of the IR and FIR transitions were made using existing microwave data.  相似文献   

8.
A series of stable and inert complexes with ErIII cores and dendritic PtII‐porphyrin ligands exhibit strong near‐IR (NIR) emission bands via highly efficient energy transfer from the excited triplet state of the PtII‐porphyrin ligand to Er3+ ions. The NIR emission intensity of thin films of ErIII complexes at 1530 nm, originating from 4f–4f electronic transitions from the first excited state (4I13/2) to the ground state (4I15/2) of the Er3+ ion, is dramatically enhanced upon increasing the generation number (n) of the aryl ether dendrons because of site‐isolation and light‐harvesting (LH) effects. Attempts are made to distinguish the site‐isolation effect from the LH effect in these complexes. Surprisingly, the site‐isolation effect is dominant over the LH effect in the Er3+‐[Gn‐PtP]3(terpy) (terpy: 2,2′:6′,2″‐terpyridine) series of complexes, even though the present dendrimer systems with ErIII cores have a proper cascade‐type energy gradient. This might be due to the low quantum yield of the aryl ether dendrons. Thus, the NIR emission intensity of Er3+‐[G3‐PtP]3(terpy) is 30 times stronger than that of Er3+‐[G1‐PtP]3(terpy). The energy transfer efficiency between the PtII‐porphyrin moiety in the dendritic PtII‐porphyrin ligands and the Ln3+ ion increases with increasing generation number of the dendrons from 12–43 %. The time‐resolved luminescence spectra in the NIR region show monoexponential decays with a luminescence lifetime of 0.98 μs for Er3+‐[G1‐PtP]3(terpy), 1.64 μs for Er3+‐[G2‐PtP]3(terpy), and 6.85 μs for Er3+‐[G3‐PtP]3(terpy) in thin films of these complexes. All the ErIII‐cored dendrimer complexes exhibit excellent thermal stability and photostability, and possess good solubility in common organic solvents.  相似文献   

9.
Layered van der Waals (vdW) magnets are prominent playgrounds for developing magnetoelectric, magneto-optic, and spintronic devices. In spintronics, particularly in spincaloritronic applications, low thermal conductivity (κ) is highly desired. Herein, by combining thermal transport measurements with density functional theory calculations, this study demonstrates low κ down to 1 W m−1 K−1 in a typical vdW ferromagnet Cr2Si2Te6. In the paramagnetic state, development of magnetic fluctuations way above Tc = 33 K strongly reduces κ via spin-phonon scattering, leading to low κ ≈ 1 W m−1 K−1 over a wide temperature range, in comparable to that of amorphous silica. In the magnetically ordered state, emergence of resonant magnon-phonon scattering limits κ below ≈2 W m−1 K−1, which will be three times larger if magnetic scatterings are absent. Application of magnetic fields strongly suppresses the spin-phonon scattering, giving rise to large enhancements of κ. This study's calculations well capture these complex behaviors of κ by taking the temperature- and magnetic-field-dependent spin-phonon scattering into account. Realization of low κ, which is easily tunable by magnetic fields in Cr2Si2Te6, may further promote spincaloritronic applications of vdW magnets. This study's theoretical approach may also provide a generic understanding of spin-phonon scattering, which appears to play important roles in various systems.  相似文献   

10.
Understanding the fundamentals of nanoscale heat propagation is crucial for next‐generation electronics. For instance, weak van der Waals bonds of layered materials are known to limit their thermal boundary conductance (TBC), presenting a heat dissipation bottleneck. Here, a new nondestructive method is presented to probe heat transport in nanoscale crystalline materials using time‐resolved X‐ray measurements of photoinduced thermal strain. This technique directly monitors time‐dependent temperature changes in the crystal and the subsequent relaxation across buried interfaces by measuring changes in the c‐axis lattice spacing after optical excitation. Films of five different layered transition metal dichalcogenides MoX2 [X = S, Se, and Te] and WX2 [X = S and Se] as well as graphite and a W‐doped alloy of MoTe2 are investigated. TBC values in the range 10–30 MW m?2 K?1 are found, on c‐plane sapphire substrates at room temperature. In conjunction with molecular dynamics simulations, it is shown that the high thermal resistances are a consequence of weak interfacial van der Waals bonding and low phonon irradiance. This work paves the way for an improved understanding of thermal bottlenecks in emerging 3D heterogeneously integrated technologies.  相似文献   

11.
Indium-selenium-based compounds have received much attention as thermoelectric materials since a high thermoelectric figure of merit of 1.48 at 705?K was observed in In4Se2.35. In this study, four different compositions of indium-selenium compounds, In2Se3, InSe, In4Se3, and In4Se2.35, were prepared by mechanical alloying followed by spark plasma sintering. Their thermoelectric properties such as electrical resistivity, Seebeck coefficient, and thermal conductivity were measured in the temperature range of 300?K to 673?K. All the In-Se compounds comprised nanoscaled structures and exhibited n-type conductivity with Seebeck coefficients ranging from ?159???V?K?1 to ?568???V?K?1 at room temperature.  相似文献   

12.
Soluble molecular red emitters 1a / 1b are synthesized by Stille coupling from 2‐(3,5‐di(1‐naphthyl)phenyl)thiophene precursors. The compounds show emission maxima at ca. 610 nm in CH2Cl2 solution and 620 nm in solid films. Replacing the n‐hexyl substituent by 4‐sec‐butoxyphenyl produces a marked increase of glass transition temperature (Tg) from 82 °C to 137 °C and increases the solubility in toluene and p‐xylene, thus improving the film‐forming properties. Cyclic voltammetry shows that the compounds can be reversibly oxidized and reduced around +1.10 and ?1.20 V, respectively. A two‐layered electroluminescent device based on 1b produces a pure red light emission with CIE coordinates (0.646, 0.350) and a maximal luminous efficiency of 2.1 cd A?1. Furthermore, when used as a solution‐processed red emitter in optically pumped laser devices, compound 1b successfully produces a lasing emission at ca. 650 nm.  相似文献   

13.
n‐Doping electron‐transport layers (ETLs) increases their conductivity and improves electron injection into organic light‐emitting diodes (OLEDs). Because of the low electron affinity and large bandgaps of ETLs used in green and blue OLEDs, n‐doping has been notoriously more difficult for these materials. In this work, n‐doping of the polymer poly[(9,9‐dioctylfluorene‐2,7‐diyl)‐alt‐(benzo[2,1,3]thiadiazol‐4,7‐diyl)] (F8BT) is demonstrated via solution processing, using the air‐stable n‐dopant (pentamethylcyclopentadienyl)(1,3,5‐trimethylbenzene)ruthenium dimer [RuCp*Mes]2. Undoped and doped F8BT films are characterized using ultraviolet and inverse photoelectron spectroscopy. The ionization energy and electron affinity of the undoped F8BT are found to be 5.8 and 2.8 eV, respectively. Upon doping F8BT with [RuCp*Mes]2, the Fermi level shifts to within 0.25 eV of the F8BT lowest unoccupied molecular orbital, which is indicative of n‐doping. Conductivity measurements reveal a four orders of magnitude increase in the conductivity upon doping and irradiation with ultraviolet light. The [RuCp*Mes]2‐doped F8BT films are incorporated as an ETL into phosphorescent green OLEDs, and the luminance is improved by three orders of magnitude when compared to identical devices with an undoped F8BT ETL.  相似文献   

14.
CH3NH3PbI3‐xClx is a commonly used chemical formula to represent the methylammonium lead halide perovskite fabricated from mixed chlorine‐ and iodine‐containing salt precursors. Despite the rapid progress in improving its photovoltaic efficiency, fundamental questions remain regarding the atomic ratio of Cl in the perovskite as well as the reaction mechanism that leads to its formation and crystallization. In this work we investigated these questions through a combination of chemical, morphological, structural and thermal characterizations. The elemental analyses reveal unambiguously the negligible amount of Cl atoms in the CH3NH3PbI3‐xClx perovskite. By studying the thermal characteristics of methylammonium halides as well as the annealing process in a polymer/perovskite/FTO glass structure, we show that the formation of the CH3NH3PbI3‐xClx perovskite is likely driven by release of gaseous CH3NH3Cl (or other organic chlorides) through an intermediate organometal mixed halide phase. Furthermore, the comparative study on CH3NH3I/PbCl2 and CH3NH3I/PbI2 precursor combinations with different molar ratios suggest that the initial introduction of a CH3NH3+ rich environment is critical to slow down the perovskite formation process and thus improve the growth of the crystal domains during annealing; accordingly, the function of Cl? is to facilitate the release of excess CH3NH3+ at a relatively low annealing temperatures.  相似文献   

15.
Semi‐ionically fluorinated graphene (s‐FG) is synthesized with a one step liquid fluorination treatment. The s‐FG consists of two different types of bonds, namely a covalent C‐F bond and an ionic C‐F bond. Control is achieved over the properties of s‐FG by selectively eliminating ionic C‐F bonds from the as prepared s‐FG film which is highly insulating (current < 10?13 A at 1 V). After selective elimination of ionic C‐F bonds by acetone treatment, s‐FG recovers the highly conductive property of graphene. A 109 times increase in current from 10?13 to 10?4A at 1 V is achieved, which indicates that s‐FG recovers its conducting property. The properties of reduced s‐FG vary according to the number of layers and the single layer reduced s‐FG has mobility of more than 6000 cm2 V?1 s?1. The mobility drastically decreases with increasing number of layers. The bi‐layered s‐FG has a mobility of 141cm2 V?1 s?1 and multi‐layered s‐FG film showed highly p‐type doped electrical property without Dirac point. The reduction via acetone proceeds as 2C2F(semi‐ionic) + CH3C(O)CH3(l) → HF + 2C(s) + C2F(covalent) + CH3C(O)CH2(l). The fluorination and reduction processes permit the safe and facile non‐destructive property control of the s‐FG film.  相似文献   

16.
Single crystal field-effect transistors (FETs) using [6]phenacene and [7]phenacene show p-channel FET characteristics. Field-effect mobilities, μs, as high as 5.6 × 10?1 cm2 V?1 s?1 in a [6]phenacene single crystal FET with an SiO2 gate dielectric and 2.3 cm2 V?1 s?1 in a [7]phenacene single crystal FET were recorded. In these FETs, 7,7,8,8-tetracyanoquinodimethane (TCNQ) was inserted between the Au source/drain electrodes and the single crystal to reduce hole-injection barrier heights. The μ reached 3.2 cm2 V?1 s?1 in the [7]phenacene single crystal FET with a Ta2O5 gate dielectric, and a low absolute threshold voltage |VTH| (6.3 V) was observed. Insertion of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) in the interface produced very a high μ value (4.7–6.7 cm2 V?1 s?1) in the [7]phenacene single crystal FET, indicating that F4TCNQ was better for interface modification than TCNQ. A single crystal electric double-layer FET provided μ as high as 3.8 × 10?1 cm2 V?1 s?1 and |VTH| as low as 2.3 V. These results indicate that [6]phenacene and [7]phenacene are promising materials for future practical FET devices, and in addition we suggest that such devices might also provide a research tool to investigate a material’s potential as a superconductor and a possible new way to produce the superconducting state.  相似文献   

17.
Modulating and constructing interface engineering is an efficient strategy to enhance catalytic activity for water splitting. Herein, a hybrid nanoarray structure of V‐CoP@a‐CeO2, where “a” represents amorphous, integrated into carbon cloth is fabricated for water splitting. The synergy effect between V and CeO2 can increase the electron density of Co atoms at active sites, further optimizing the Gibbs free energy of H* adsorption energy (ΔGH*). Besides, V‐CoP@a‐CeO2 possesses lower water adsorption/dissociation energies, enabling accelerated reaction kinetics in alkaline media. As expected, the V‐CoP@a‐CeO2 exhibits superior performance toward the hydrogen evolution reaction and the oxygen evolution reaction. More importantly, a two‐electrode electrolyzer combined with an electrocatalyst of V‐CoP@ a‐CeO2 only demands that voltages of electrolytic cell are 1.56 and 1.71 V to achieve the current densities of 10 and 100 mA cm?2, respectively. This work provides guidance for the design or optimization of materials for water electrolysis and beyond.  相似文献   

18.
[ThB5O6(OH)6][BO(OH)2]·2.5H2O (Notre Dame Thorium Borate‐1, NDTB‐1) is an inorganic supertetrahedral cationic framework material that is derived from boric acid flux reactions. NDTB‐1 exhibits facile single crystal to single crystal anion exchange with a variety of common anions such as Cl?, Br?, NO3?, IO3?, ClO4?, MnO4?, and CrO42?. More importantly, NDTB‐1 is selective for the removal of TcO4? from nuclear waste streams even though there are large excesses of competing anions such as Cl?, NO3?, and NO2?. Competing anion exchange experiments and magic‐angle spinning (MAS)‐NMR spectroscopy of anion‐exchanged NDTB‐1 demonstrate that this unprecedented selectivity originates from the ability of NDTB‐1 to trap TcO4? within cavities, whereas others remain mobile within channels in the material. The exchange kinetics of TcO4? in NDTB‐1 are second‐order with the rate constant k2 of 0.059 s?1 M?1. The anion exchange capacity of NDTB‐1 for TcO4? is 162.2 mg g?1 (0.5421 mol mol?1) with a maximum distribution coefficient Kd of 1.0534 × 104 mL g?1. Finally, it is demonstrated that the exchange for TcO4? in NDTB‐1 is reversible. TcO4? trapped in NDTB‐1 can be exchanged out using higher‐charged anions with a similar size such as PO43? and SeO42?, and therefore the material can be easily recycled and reused.  相似文献   

19.
An increase in the energy density of lithium‐ion batteries has long been a competitive advantage for advanced wireless devices and long‐driving electric vehicles. Li‐rich layered oxide, xLi2MnO3?(1?x)LiMn1?y?zNiyCozO2, is a promising high‐capacity cathode material for high‐energy batteries, whose capacity increases by increasing charge voltage to above 4.6 V versus Li. Li‐rich layered oxide cathode however suffers from a rapid capacity fade during the high‐voltage cycling because of instable cathode–electrolyte interface, and the occurrence of metal dissolution, particle cracking, and structural degradation, particularly, at elevated temperatures. Herein, this study reports the development of fluorinated polyimide as a novel high‐voltage binder, which mitigates the cathode degradation problems through superior binding ability to conventional polyvinylidenefluoride binder and the formation of robust surface structure at the cathode. A full‐cell consisting of fluorinated polyimide binder‐assisted Li‐rich layered oxide cathode and conventional electrolyte without any electrolyte additive exhibits significantly improved capacity retention to 89% at the 100th cycle and discharge capacity to 223–198 mA h g?1 even under the harsh condition of 55 °C and high charge voltage of 4.7 V, in contrast to a rapid performance fade of the cathode coated with polyvinylidenefluoride binder.  相似文献   

20.
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   

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