Coherent detection of M-ary phase-shift keying in thesatellite mobile channel with tone calibration

A formula is derived for the error probability of M-ary phase-shift keying (PSK) in the satellite mobile channel when the signal is accompanied by a pilot tone which is used in the receiver for coherent detection of the signal. The author computes the error probability as a function of the signal-to-noise ratio, the ratio of powers in the specular and diffused signal component, the ratio of bandwidth in the pilot tone and signal extraction filters, and the numbers of symbols, i.e. M, while optimizing the ratio of powers in the pilot tone and signal. He computes results when the diffused component is not delayed with respect to the specular component, as well as for the opposite case, i.e. when the symbol in the diffused component is independent of the symbol in the main component     

M-ary CPFSK-DPD with L-diversity maximum ratio combining in Ricianfast-fading channels

We derive a formula for the bit error probability (BEP) of M-ary continuous phase frequency shift keying with differential phase detection and maximum ratio combining diversity in Rician fast-fading channels. We assume that transmitter and receiver filters distort the signal and limit the noise. We compute the BEP as a function of energy-to-noise ratio per bit (E_b/N₀) and other system and channel parameters: Rician factor K=0, 6 dB, 10, ∞; number of diversity channels L=1, 2, 3; Doppler frequency shift f_D T=0, 0.01, 0.02; Butterworth filters in transmitter and receiver of order N_T=3 and N_R=4; optimal sampling time and filter bandwidth. In all cases the BEP is significantly reduced by diversity     

Activity-dependent plasticity of synaptic efficacy at inhibitory junctions

Despite a considerable amount of investigation on long-term potentiation, the question of whether this process occurs at inhibitory synapses has remained controversial until studies of these junctions have been achieved in the Mauthner cell of Teleosts. In this preparation, inhibitory long-term potentiation similar to that occurring at hippocampal excitatory synapses has been demonstrated.     

Q2DPSK in the satellite mobile channel with ISI and CSI

The authors analyze the performance of quadrature-quadrature differential phase shift keying (Q²DPSK) in the satellite mobile channel. The expression for the bit error probability takes into account both intersymbol and cross-symbol interference (ISI and CSI). Numerical results are presented for three different pulse pairs. It is shown that Q²DPSK with 4 symbols outperforms DPSK with 8 symbols. They conclude that Q²DPSK is both power and bandwidth efficient for the satellite mobile channel which includes as special cases the Gaussian and Rayleigh channels     

Relation between bit and symbol error probabilities for FSK withLDI detection

In M-ary, Gray coded digital communication the bit error probability is usually approximated by the symbol error probability divided by the number of bits in a symbol. This approximation is known to be excellent for phase shift keying with coherent detection at high-signal-to-noise ratios and Gaussian channel. Here it is illustrated that this approximation may also be good for M-ary frequency shift keying with limiter-discriminator-integrator detection on Gaussian, Rayleigh, and Rician channels     

GMSK with limiter-discriminator detector in Nakagami fading channel with and without selection combining

We derive an equation for the bit-error probability (BEP) of Gaussian minimum-shift keying with limiter discriminator detection in Nakagami-m fading channels including selection and switch-and-stay combining. We compute the BEP for various selections of system parameters.     

Author Index

The enantioselective hydrogenation of ethyl benzoylformate to (R)-ethyl mandelate over dihydrocinchonidine (DHCD)-modified Pt/Al₂O₃ catalyst in acetic acid was studied as a function of modifier concentration, hydrogen pressure and reaction temperature. The maximum enantioselectivity obtained under optimized conditions (DHCD concentration 1 mmol dm^-3, 25 bar H₂, 0 °C, AcOH/toluene 1:1) was 98% ee. The difference between the rates of racemic and enantioselective hydrogenation was less significant than in the case of ethyl pyruvate. This indicates that the high reaction rate in the enantioselective heterogeneous hydrogenation of -ketoesters is not a necessary condition of the chiral induction.     

Investigation of the thermoformability of various D-Lactide content poly(lactic acid) films by ball burst test

In this article, we investigated the thermoformability of poly(lactic acid) (PLA) films with various D -Lactide contents and therefore different crystallization properties, performing tensile and ball burst tests at various temperatures and testing rates. We found that the behavior of the PLA films tested above the glass transition temperature significantly differs due to the difference in D -Lactide content, and thus crystallinity. During tensile testing, elevated temperatures and mechanical stress caused the crystallization temperature to decrease and thus highly induced crystallization. At the same time, as testing speed was increased, the ability of the polymer to crystallize decreased. In ball burst tests, the PLA films crystallized more than during tensile testing. We described the differences found between tensile testing and ball burst testing, which latter better represents the conditions of thermoforming through inducing biaxial deformation.     

Climatic conditions for operation of wind turbines in Hungary

According to wind-climatic requirement of wind farms wind speed should exceed the so called cut-in speed. If this inequality is realized then regarding the wind-climatic features of Hungary the following conditions may occur: the wind turbine is operating with high probability, energy is generated; it is working in a regulated mode with low probability; it is not working with very low probability. Therefore in terms of continuous energy production by wind one question arises: are there any temporal and/or orographic shifts in different heights compared to the wind-climatic condition mentioned above. In this paper this question is analyzed on the basis of seven Hungarian meteorological stations that have hourly measured wind speed data considering the period between 1991 and 2000. The probability of wind speeds exceeding 3 m/s, statistics of wind speed intervals higher and lower than 3 m/s and statistics of average hourly wind speed intervals higher than 3 m/s were analyzed at the heights of 10, 30 and 60 m. A statistical parameter that is proportional to the average specific wind power of a day in a time period was defined and, its connection to the average length of those intervals that have higher or equal hourly average wind speeds more than 3 m/s in a given month was investigated. With the help of such parameters the value of monthly average specific wind power can be estimated.