Unambiguous sine-phased binary offset carrier modulated signal acquisition technique

In this letter, a side-peak cancelation unambiguous acquisition technique is proposed for sine-phased binary offset carrier (BOC) modulated signals. The test criterion used in this technique is based on a synthesized correlation function which has no major positive side peak. This synthesized correlation function is obtained by subtracting the cross-correlation between the received sin-BOC signal and an auxiliary signal from the autocorrelation of sin-BOC signal. For different types of BOC signal, the proposed technique employs corresponding modulated symbols of the auxiliary signal. The common solution of the symbol shape vector is derived, and the theoretical false alarm and detection performance formulas are given. Theoretical and simulation results show that at the expense of some performance degradation this technique completely removes the ambiguity threat in acquisition process.     

Opportunistic decoding of unequal erasure protected scalable coded source

In this paper,we propose an opportunistic decoding method to enhance the reconstruction of unequal erasure protected scalable coded source.This method explores some non-channel-decodable symbols of the received packets by opportunistically utilizing the structure information of joint source-channel coding scheme.As a result,a longer prefix of source coded stream may be obtained to enhance the reconstruction of scalable coded source.Experiment results indicate that opportunistic decoding at the receiver can ...     

Surface-tension measurements of the eutectic alloy (Ag-Sn 96.2 at.%) with Cu additions

The maximum bubble-pressure method has been used to measure the surface tension and density of liquid alloys (Ag-Sn)_eut + Cu (X_Cu = 0.005, 0.020, 0.0375, and 0.065 (mole fraction)). The surface tension and density measurements were curried out in the temperature ranges of 262–942°C and 264–937°C, respectively. The linear dependencies of surface tensions and densities on temperature were observed, and they were described by straight-line equations. It has been found that the additions of Cu to the Ag-Sn eutectic alloy increase the surface tension. Experimental data of the surface tension were compared with those from modeling based on Butler’s method, using the optimized-thermodynamic parameters from the literature, and a slight tendency contrary to the experimental results was observed.     

Time-resolved photoluminescence of polycrystalline GaN layers on metal substrates

The low-temperature time-resolved photoluminescence of polycrystalline GaN layers grown by molecular beam epitaxy on metal substrates (Mo and Ta) was investigated. The photoluminescence spectra observed include two emission bands in the ultraviolet spectral region. We assign one of these bands to recombination processes inside cubic nanocrystallites, which are formed in the hexagonal polycrystalline GaN host. The recombination radiation of cubic nanocrystallites is enhanced due to predominant trapping of the nonequilibrium electron-hole pairs in these crystallites.     

Power aware channel width tapering of serially connected MOSFETs

This paper reviews a transistor channel width tapering scheme called Hill Tapering for FET chains with specific emphasis on power dissipation and layout area of the tapered chains. The Hill Tapering scheme results in the lowest power dissipation and physical area compared to any of the existing tapering schemes like linear, exponential or optimal tapering. It also offers high speed operation. This tapering scheme is general and suits domino logic circuit designs. SPICE simulation results have shown that up to 81% power dissipation reduction could be achieved by using this tapering scheme.     

Joint Carrier Frequency Offset Estimation and Compensation for Downlink Group-Orthogonal Multicarrier CDMA

A carrier frequency offset (CFO) estimation and compensation method is proposal for downlink group-orthogonal multicarrier code-division multiple-access (GO-MC-CDMA) system. The proposed algorithm has taken into consideration both the inherent orthogonality among subcarriers of different groups of GO-MC-CDMA system and the characteristics of Fast Fourier Transform (FFT) demodulation are taken into consideration. The CFO estimation is achieved by searching the value which minimizes the cost function constructed in terms of performing FFT on the interfering signals. Simulation results show that the estimated value of CFO is very close to the real value for the downlink GO-MC-CDMA system. In addition, it is shown that the bit error rate (BER) performance is improved significantly by CFO compensation.     

Annealing-Induced Morphological Changes in Nanocrystalline Quantum Dots and Their Impact on Charge Transport Properties

The effects of thermal annealing on the morphological and photoconductive properties of cadmium selenide quantum dots coated with zinc sulfide are studied. The results of transmission electron microscopy with in situ annealing show a number of events taking place simultaneously, including aggregation of dots, changes in the size and shape distribution, and reduction in interdot separation. Transient absorption results indicate that there is a small redshift of the spectrum. There is a shortening of the absorption decay lifetimes due to annealing. Higher photocurrents are measured in the annealed compared with unannealed dots at room temperature.     

The Performance of ST-Turbo TC Based on the Improved Log-MAP Algorithm

The iterative decoding in turbo code has very high decoding complexity. This paper adopts the improved Log-MAP algorithm for decoding of Space-Time Turbo Trellis Code (ST-Turbo TC) in the slow Rayleigh fading channels. Using the MacLaurin formulae, the proposed algorithm expands the logarithmic function of the Log-MAP. It makes the computation much easier and the operation of the hardware system much faster. Simulation results show that the proposed algorithm performs very closely to the Log-MAP algorithm for decoding of ST-Turbo TC in slow Rayleigh fading channels.     

A Signed Array Multiplier with Bypassing Logic

A low power digital signed array multiplier based on a 2-dimensional (2-D) bypassing technique is proposed in this work. When the horizontally (row) or the vertically (column) operand is zero, the corresponding bypassing cells skip redundant signal transitions to avoid unnecessary calculation to reduce power dissipation. An 8×8 signed multiplier using the 2-D bypassing technique is implemented on silicon using a standard 0.18 μm CMOS process to verify power reduction performance. The power-delay product of the proposed 8×8 signed array multiplier is measured to be 31.74 pJ at 166 MHz, which is significantly reduced in comparison with prior works.     

Controlled Synthesis of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>/Ag Core–Shell Composite Nanoparticles with High Electrical Conductivity

The presented method provides an easy processing route to synthesize Fe₃O₄/Ag core–shell composite nanoparticles. Their structures were characterized by x-ray diffraction and transmission electron microscopy. The average size of the Fe₃O₄ core and Ag shell was about 32.0 nm and 5.0 nm (or 28.0 nm), respectively. Furthermore, magnetic measurements showed that the composite nanoparticles exhibited typical superparamagnetic behavior, specific saturation magnetization of ca. 24.0 emu/g, and intrinsic coercivity of 106.0 Oe. At the same time, high conductivity (64.7 S/cm) of the composite nanoparticles was also observed. This method provides an opportunity to synthesize other core–shell (Fe₃O₄) nanoparticles in a single step.