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91.
Chakraborty Shyam S. Liinaharja Markku Lindroos Petri 《Wireless Personal Communications》2003,26(4):347-363
In this article, an adaptive SR ARQ scheme is analyzed and optimized in a time-varying channel environment with unreliable feedback. To have an operational scheme, we choose the smaller packet size to be half of the bigger one. Thus, there is only one independent design parameter related to packet size. The other two parameters are associated with channel sensing. The performance of the adaptive scheme is measured by its average throughput, which is upper-bounded by the throughput of the so-called ideal adaptive scheme. This upper bound is very useful in the optimization of the packet size and other design parameters. 相似文献
92.
The HArF molecule can occupy in solid Ar thermally unstable and stable configurations, and their microscopic structure is not understood at the moment. We present additional experimental results on the formation of two HArF configurations and analyze them with emphasis on possible reactions of the unstable configuration with matrix vacancies to form the stable configuration. We conclude that the existing computational scenarios do not describe fully the present experimental data. In order to explain qualitatively the experimental results, two tentative models are discussed. The first model is based on local mobility of matrix vacancies produced during photolysis and the second model considers isomerization of the HArF at Arn supermolecule. More importantly, the present results constitute the experimental basis for future theoretical studies. 相似文献
93.
Colacio E Lloret F Kivekäs R Ruiz J Suárez-Varela J Sundberg MR 《Chemical communications (Cambridge, England)》2002,(6):592-593
A 2D grid-shaped cyanide-bridged Co(II)-Au(I) bimetallic coordination polymer, [Co(DMF)2(Au(CN)2)2], has been prepared from the [Au(CN)2]- building block; sheets associate pair-wise by aurophilic interactions and the compound exhibits zeolite-like properties. 相似文献
94.
We propose an optical system to implement rewritable transparent broad-band color filters. The filter consists of a linear variable filter and a liquid crystal spatial light modulator in which an expected filter function is written. A time-integrated intensity image was taken while the filter was passing the lens aperture of a CCD camera. The averaged norm error between the implemented and the expected filter functions was about 5.4#x0025;. The system was applied to spectral estimation in a two-dimensional color image. 相似文献
95.
Paula Aulaskari Markku Ahlgrn Pirjo Vainiotalo Esko Pohjala 《Journal of heterocyclic chemistry》2000,37(1):87-93
New high yield preparation methods were developed for the pharmaceutically interesting compounds, 1‐benzyl‐, 1‐methyl‐, and 1H‐5‐[(2‐oxo‐2‐phenyl)ethyl]imidazoles 1a‐c , respectively. The title compounds were synthesized by four different methods using various starting materials. Two of the methods involved transformation reactions of the key intermediates, 1‐substituted‐5‐[(2‐nitro‐2‐phenyl)ethenyl]imidazoles 2a‐c and 1‐substituted‐5‐[(2‐nitro‐2‐phenyl)ethyl]imidazoles 3a‐c , while the other two utilized the oxidation of 1‐substituted‐5‐[(2‐hydroxy‐2‐phenyl)ethyl]imidazoles 4a‐c , with chromic oxide, and the umpolung reaction of benzaldehyde followed by a condensation reaction of the umpolung intermediate with imidazolecarboxaldehydes 6a‐c. 相似文献
96.
Adnan S. Abu‐Surrah Martti Klinga Timo Repo Markku Leskel Tony Debaerdemaeker Bernhard Rieger 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(2):e44-e45
The title compound was formed upon slow evaporation of a solution of the solvated dicationic complex bis(acetonitrile)bis[1,2‐bis(diphenyl‐phosphino)ethane]palladium(II) bis(tetrafluoroborate) in deuterated chloroform. The dinucleur palladium complex forms triclinic crystals and there is an inversion center between the Pd atoms. Compared to the corresponding monomeric compound, the Cl—Pd—Cl angles decrease upon briding from 94.19 (7) to 86.96 (4)°. 相似文献
97.
Juha-Veikko Voutilainen Juha Häkkinen Markku Moilanen 《Microelectronics Reliability》2011,51(2):425-436
This article presents a method for estimating solder interconnection failure times based on nonlinear parameter estimation techniques in conjunction with the Levenberg-Marquardt Algorithm (LMA). The LMA algorithm is applied to precursor measurements, from which failure time estimations are deduced using nonlinear estimation parameters. An electrical behavioural model is also proposed for precursors indicating weakening of solder interconnections. This model is divided into three sections: linear region, conversion region and nonlinear portion. Results obtained from experimental studies are presented and discussed in detail. In addition, an error estimation of the results is conducted to obtain knowledge of the most critical parameters in the estimation problem.The results suggest that the proposed method is capable of predicting solder interconnection failure times in advance, provided that the precursor describing electronic fatigue damage in interconnections obeys the exponential growth model during the wear-out period of the interconnection life-cycle. The obtained prognostic distances (PDs) varied between 15% and 38%, and failure times were predicted 15-25% before the actual failure occurred with an error rate of less than 10%. To show the generality of the proposed method, experimental results are presented for several samples with both lead and lead-free solders. 相似文献
98.
Stable operation of a cw optical parametric oscillator near the signal-idler degeneracy 总被引:1,自引:0,他引:1
The frequency stability of a cw optical parametric oscillator (cw OPO) near the signal-idler degeneracy has been studied. The strong tendency of a near-degenerate OPO to mode hop has been suppressed by using a bulk Bragg grating as a spectral filter in the OPO cavity. An experimental demonstration of stable parametric oscillation in a single longitudinal mode of the OPO cavity is reported, together with the capability of tuning the signal-idler difference frequency from 1 to 4 THz. The OPO has potential use in cw terahertz generation. 相似文献
99.
Kari Kopra Alessio Ligabue Qi Wang Markku Syrjänpää Olga Blaževitš Stefan Veltel Arjan J. van Adrichem Pekka Hänninen Daniel Abankwa Harri Härmä 《Analytical and bioanalytical chemistry》2014,406(17):4147-4156
A quenching resonance energy transfer (QRET) assay for small GTPase nucleotide exchange kinetic monitoring is demonstrated using nanomolar protein concentrations. Small GTPases are central signaling proteins in all eukaryotic cells acting as a “molecular switches” that are active in the GTP-state and inactive in the GDP-state. GTP-loading is highly regulated by guanine nucleotide exchange factors (GEFs). In several diseases, most prominently cancer, this process in misregulated. The kinetics of the nucleotide exchange reaction reports on the enzymatic activity of the GEF reaction system and is, therefore, of special interest. We determined the nucleotide exchange kinetics using europium-labeled GTP (Eu-GTP) in the QRET assay for small GTPases. After GEF catalyzed GTP-loading of a GTPase, a high time-resolved luminescence signal was found to be associated with GTPase bound Eu-GTP, whereas the non-bound Eu-GTP fraction was quenched by soluble quencher. The association kinetics of the Eu-GTP was measured after GEF addition, whereas the dissociation kinetics could be determined after addition of unlabeled GTP. The resulting association and dissociation rates were in agreement with previously published values for H-RasWt, H-RasQ61G, and K-RasWt, respectively. The broader applicability of the QRET assay for small GTPases was demonstrated by determining the kinetics of the Ect2 catalyzed RhoAWt GTP-loading. The QRET assay allows the use of nanomolar protein concentrations, as more than 3-fold signal-to-background ratio was achieved with 50 nM GTPase and GEF proteins. Thus, small GTPase exchange kinetics can be efficiently determined in a HTS compatible 384-well plate format. Figure
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100.
Tuomo Hänninen Janne Janhunen Markku Juntti 《Analog Integrated Circuits and Signal Processing》2014,78(3):645-655
We summarize our recent state-of-the-art programmable and reconfigurable detector and QR decomposition (QRD) implementations targeting 3G long term evolution (LTE) downlink and uplink requirements. The downlink transmission is based on the orthogonal frequency division multiplexing, whereas the uplink transmission uses a single-carrier frequency-division multiple access. The downlink implementations are based on the programmable transport triggered architecture (TTA) which provides a flexible and energy efficient architecture template. In TTA detector implementation, the LTE detection rate requirements up to 20 MHz bandwidth and 4 × 4 antenna system with 64-QAM, are achieved by using 1–6 programmable cores in parallel. Each core runs at 277 MHz clock frequency and consumes 55.5–64.0 mW depending on the detector configuration. The downlink detector is based on the selective spanning with fast enumeration algorithm. The uplink field-programmable gate array (FPGA) detector implementation is targeted for 4 × 4 antenna system and 64-QAM achieving a detection rate requirement for 20 MHz bandwidth. The used FPGA board for uplink implementation is Xilinx Virtex-6 and the implementation has been carried out using Xilinx Vivado high level synthesis tool. Two different detector architectures are implemented. The first one achieves the detection rate requirement with a single processing block running at 231 MHz and the latter one with four blocks in parallel, each running at 247 MHz. The implemented detector is based on the K-best algorithm. A multiple-input multiple-output receiver requires QRD to produce valid inputs for the detector. In addition to detector implementations, QRD is also implemented on both TTA and FPGA. Modified Gram–Schmidt algorithm is used in both QRD implementations. 相似文献