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The variation of fuel loads after a fire for three forest types,phododendron--Larix gmelinii forest,herb--Larix gmelinii forest andherb--Betula platyphlla forest, in the northern forest area of Daxing’anling region was discussed. The dynamic models were developed by gray theory for estimating the fuels loads of arbor, shrub, herbs, grass, litter, and semi-decomposed litter, inflammable fuel and the total fuels in each forest type. After a fire, the inflammable fuel loads inphododendron-Lxirix gmelinii forest and in the herb- -Betula platyphlla fores was estimated at 10.958 t/hm2 and 10.473 t/hm2 respectively, by 13 years later, and that was 12.297 t/hm2 inherb--Larix gmelinii forest by 7 years later. It was predicated that a big fire may occur after 10 years based on inflammable fuel biomass accumulated.

The site index table, site class table and quantizing model of dahurian larch forests were formed based on 418 temporary plots and 179 dominant stem analysis trees. By testing raw data which were not used to form the site index table, the site index table of plantations was validated. The site index table or site class table can be used in timber stands according to the intensive degrees of forest management. The quantizing model can be used in cutover, deforested and nonforested areas.

The fuel moisture content is an integral part of any workable fire danger-rating system. This paper presented dynamic models for estimating 1-h, 10-h, 100-h and 1000-h timelag fuels, that were developed by multiple regression and stepwise variable selection of statistics. The variables include both meteorological factors and moisture contents observed prior to the day correspondingly. The analysis revealed that the fuel moisture content are correlated positively with the precipitation of 24 hours prior to the observation time, and negatively with air temperature at observing height of 1.5 meter in forest.

Multiple transmit-and-receive antennas can be used in orthogonal frequency division multiplexing (OFDM) systems to improve communication quality and capacity. In this paper, an improved channel estimation for MIMO-OFDM system is proposed by exploiting a new method of pilot insert by which pilots are inserted into different carriers at different time. The method can estimate the CSI of all frequencies, so it will enhance the ability to resist frequency selective fading. Then it regards the results of interpolation as pre-estimation and takes different Averaged Channel Estimation in the Time-domain (ACE-T) on different channel conditions to get final channel estimation. The effectiveness of the new technique is demonstrated through the simulation of an OFDM system with two-transmit and two-receive antennas.

In this paper, we propose a new frequency synchronization algorithm for orthogonal frequency division multiplexing (OFDM) system by combining PN sequences with cyclic prefix. It is the improvement of Tufvesson's algorithm. In the new algorithm, the frequency offset is estimation with two steps. First a small step (span of the correlation) is used to estimate frequency offset which will result in a larger estimation range but less precise. After the frequency offset has been compensated, the second estimation using cyclic prefix is conducted which is a large step. The new algorithm has large estimation range and the estimation is more precise. Performance of the new estimator improved than that of the old one in AWGN channel and multipath fading channel.

This paper deals with the chip-level equalization technique for large area synchronized-code division multiple access (LAS CDMA) system communications. In the downlink of LAS CDMA, frequency-selective multi-path channel often destroys the orthogonality of spread codes at receivers between users and introduces inter-path interference (IPI), inter-symbol interference (ISI) and multi-path access interference (MAI). The conventional RAKE receiver is limited in suppressing IPI and MAI. Chip equalization is an efficient tool to restore the orthogonality of the user signals. So we focus on a new chip equalization scheme of receiver based on three criterions, and proposed the adaptive implementation algorithms. Simulation results show improved performance as compared with the RAKE receiver for the CDMA downlink.

In this paper, we propose a constrained least mean square error cost function, which is subject to a quadratic function. It is not different from all of the previous ones, such as in (Daoben Li., Beijing Uni. of Posts and Telecom. Press, p.258-266, 1995), for equalization. The implementation algorithm is a derivative of the previous one for this constrained criterion. A performance comparison is shown between the constrained and unconstrained algorithm.

A new method was proposed to study the dynamics of stem form of natural Korean pine (Pinus koraiensis) tree. In natural Korean Pine forest, the occurring time of maximum height and diameter is very difference. This paper connected stem form to stage of tree growth to analysis the form dynamic of Korean pine. The monpmolecular equation was chosen as the stem model. The result shows that the maximum growth year of natural Korean pine is earlier than diameter.