Lower bound on BER performance for maximal ratio combining with weighting errors

The theoretical lower bounds on mean squared channel estimation errors for typical fading channels are presented by the infinite-length and non-causal Wiener filter and the exact closed-form expressions of the lower bounds for different channel Doppler spectra are derived. Based on the obtained lower bounds on mean squared channel estimation errors, the limits on bit error rate （BER） for maximal ratio combining （MRC） with Gaussian distributed weighting errors on independent and identically distributed （i. i. d） fading channels are presented. Numerical results show that the BER performances of ideal MRC are the lower bounds on the BER performances of non-ideal MRC and deteriorate as the maximum Doppler frequency increases or the SNR of channel estimate decreases.

Research and Simulation on Weak Signal Detection Based on Duffing Oscillator and Damping Ratio Perturbation

The chaotic system is sensitive to the initial value, and this can be applied in the weak signal detection. There are periodic, critical and chaotic states in a chaotic system. When the system is in the critical state, a small perturbation of system,n parameter may lead to a qualitative change of the system＇s state. This paper introduces a new method to detect weak signals by the way of disturbing the damping ratio. The authors choose the duffing equation, using MATLAB to carry on the simulation, to study the changes of the system when the signal to be measured is added to the damping ratio. By means of observing the phase loots chart and time damin chart, the weak signal will be detected.

IMPROVED MLV FILTER TO REMOVE MULTIPLICATIVE NOISE

More methods can be used to remove the additive noise, such as the Mean of Least Variance (MLV) filter. When the signal is noised by the multiplicative noise, it is difficult to remove. The paper presents an improved filter to remove multiplicative noise by changing the multiplicative noise to the additive noise, and then using the MLV-like to remove the additive noise. The simulation results show that the performance is better than Minimum Coefficient of Variation (MCV) filter and MLV filter. Both one-dimension and image experiments demonstrate its theoretical performance.

Demythologizing the South： Cormac McCarthy＇s Suttree in an Intertextual Perspective

The article is structured around a premise of intertextuality, which is suggested not only by McCarthy＇s own more or less overt allusions to Faulkner＇s writing but also by the very name of his protagonist Suttree, which is evocative of the name of perhaps the best known Faulkner villain Thomas Sutpen. This supposition in turn leads to an argument that in his 1979 novel McCarthy does indeed reverse the life story of Thomas Sutpen by making Suttree descend down the very path that Sutpen ascended a century and a half before him, i.e., from the ranks of Southern aristocracy to the scum of the earth, and in defiance of the same ideology that Sutpen went to great lengths to embrace. Thus, an intertextual and comparative approach to McCarthy＇s novel not only in the context of Faulkner＇s Absalom, Absalom! but also his Light in August （cf. Joe Christmas） and The Sound and the Fury （cf. Quentin） as well as Ellen Glasgow＇s short story ＂Jordan＇s End＂ demonstrates that what Cormac McCarthy actually does in Suttree is to demythologize the South, complete with its aristocratic pretensions （＂doing pretty＂）, dubious morality （incest） and fear of miscegenation （obsession with time and the double）. Moreover, in doing so, he defamiliarizes it by reducing it to its Other （poor whites and African Americans）, whose authenticity, liveliness and charitability defy the affectation, lifelessness and decadence of the aristocratic South.

Parameter identification of inertially stabilized platforms using current command design

Accurate parameter identification is essential when designing controllers for inertially stabilized platforms （lSPs）. But traditional identification methods suffer from observation measurement noise and operating restrictions of ISPs. To address this issue, a novel identification method based on current command design and multilevel coordinate search （MCS） algorithm without any higher order measurement differentiations was proposed. The designed current commands were adopted to obtain parameter decoupled models with the platform operating under allowable conditions. MCS algorithm was employed to estimate the parameters based on parameter decoupled models. A comparison experiment between the proposed method and non-linear least square method was carried out and most of the relative errors of identified parameters obtained by the proposed method were below 10%. Simulation and experiment based on identified parameters were conducted. A velocity control structure was also developed with disturbance observer （DOB） for application in disturbance compensation control system of an ISR Experimental results show that the control scheme based on the identified parameters with DOB has the best disturbance rejection performance. It reduces the peak to peak value （PPV） of velocity error integral to 0.8 mrad which is much smaller than the value （10 mrad） obtained by the single velocity controller without DOB. Compared with the control scheme based on sweep model with DOB compensation, the proposed control scheme improves the PPV of velocity error integral by 1.625 times.

Evapotranspiration and ratio of soil evaporation to evapotranspiration of winter wheat and maize in north China

Evapotranspiration （ETc） is an important quantity for hydrological cycle. This study shows evapotranspiration, the ratio of evaporation to evapotranspiration （E/ETc） of winter wheat and maize in north China. Several relationships, namely, E/ET0 and soil surface moisture, E/ET0 and leaf area index （LAI）, are also analyzed. The average seasonal ETc values for winter wheat, maize （2008） and maize （2009） are 431.21,456.3 and 341.4mm. The value of E/ET0 varied from 1 at initial growth stage to 0.295 at the later growth for winter wheat, and from 1 to 0.492, from 1 to 0.566 for maize （2008） and maize （2009）. The relationship between E/ET0 and surface soil water content, and E/ET0 and LAI are fitted to a quadratic parabola equation with significant correlation coefficients, respectively, for wheat and maize. These results should help the precise planning and efficient management of irrigation for these crops in this region.