Wireless Personal Communications - Due to the development and growth of Internet platforms and web services as communication resources, the competition for the network and its limited resources is... 相似文献
Two approaches are introduced for the identification of linear time-invariant systems when only output data are available. The input sequences are independent and must be non-Gaussian. To estimate the parameters of the system, we use only the fourth-order cumulants of the output, which may be contaminated by an additive, zero mean, Gaussian noise of unknown variance. To measure the performance of the proposed algorithms against existing methods, we compared them with the Zhang's algorithm. Simulations verify an apparent performance of the second algorithm, compared with the first and Zhang's algorithms, in a low signal-to-noise ratio and for small data. The simulation results show that the first algorithm has the same performance compared with Zhang's one. But the second algorithm achieves better performance compared with the first and Zhang is algorithm. For validation purposes, the second algorithm is used to search for a model able to describe and simulate the data set representing the wind speed. 相似文献
This paper presents ARMA models of the weather parameters: ambient temperature, humidity and clearness index recorded at or near Marrakech. The identification of the model parameters is based on Higher Order Statistics (cumulants). Comparison between the statistical characteristics of the measured data and the data generated using the models has been performed, and the results show that the weather parameters can be predicted with acceptable accuracy. 相似文献
A cleaning resin has been developed for the non-chromatographic purification of 99mTc-labeled monoclonal antibodies (MAbs). The resin used is a modified form of thiopropylsepharose 6B resin, in which its sulfhydryl groups have been tinylated with stannous chloride. The method requires only simple stirring of the radiolabeling reaction mixture with this tinylated resin and subsequent separation of it from the resin by filtration to obtain a 99mTc-labeled MAb of radiopharmaceutical purity. The method provides an alternative to chromatographic purification of the radiolabeled MAb (i.e. gel filtration or anion exchange chromatography) which has been used in other 99mTc-MAb preparations. For comparison studies, we labeled the B72.3 MAb with NeoRx's diamide dimercaptide chelate radiolabeling kit, split the reaction mixture into two equal portions and then purified one portion with anion exchange chromatography (NeoRx's chosen method) while the other portion was purified with our cleaning resin. Comparison of HPLC chromatograms, percent 99mTc-bound to MAb, biodistribution and scintigraphic results show that our cleaning resin methodology provides a 99mTc-labeled MAb of essentially equal purity and utility as does the established, chromatographic one. 相似文献
In this study, a new method is proposed for determining the thermal performance parameters of a flat-plate water heating collector. A parametric identification principle is applied to a mathematical model of the collector operating in a real system. The advantages of the method are that it does not need a sophisticated testing system, it avoids the problem of regulating the inlet fluid temperature (which must be held constant during the tests in the standard procedures) and a cloudless sky is not essential. Solar radiation of 600 W m−2 was chosen as a threshold to start experiments. Applied to a flat-plate collector with a single-glazed cover, the proposed method gave satisfactory results for the determination of its thermal performance coefficients. To verify the adequacy of the present method, it was used to predict the outlet fluid temperature. The results indicate a satisfactory agreement between predicted and measured values with a correlation coefficient of 0.99 and an error of 0.4%. We propose that performance results will be presented as a technical sheet showing collector features and accompanied with a curve giving the correlation between estimated and measured output temperature of the collector fluid. 相似文献
This work addresses channel estimation (CE) in the uplink phase for a cell-free massive multiple-input multiple-output system operating under the time division duplex protocol. Considering that, channels are spatially correlated under the Rician fading model, where the investigated model is composed of two components: deterministic and nondeterministic, with the deterministic component describing the line-of-sight paths and the nondeterministic component describing the non-line-of-sight paths. Additionally, we dealt with correlated shadow fading that represents the most realistic situation. On the other hand, this work introduces a dynamic cooperation cluster framework in which the user is not served with the whole network ( i.e., all access points [APs]) but only the APs that present the best channel conditions regarding that user. In other words, this work proposes partial CE for each user because only APs with the best channel conditions are allowed to compute channel estimates. Consequently, we proposed partial channel estimators that perform the CE process with low complexity, namely, a partial minimum mean square error estimator and a partial element-wise minimum mean square error estimator. In addition, a simple pilot assignment technique is proposed in order to reduce interference signals so that each user experiences low interference from other users. Furthermore, the computational complexity required by each estimator is derived, where it is represented by the number of complex multiplications that each estimator requires in each consistency block. Theoretical and simulated results are provided, where the performance of each estimator is evaluated and analyzed using the normalized mean-square error metric. 相似文献
The upper bound capacity based on the SINR model is a very important parameter when evaluating the performance of the multi-hop wireless ad hoc networks. In this paper, a new upper bound capacity algorithm is proposed. Firstly, we analyzed the classical physics SINR model over the Rayleigh fading channels to establish the relationship between density of nodes and path outage probability. Then, we developed the closed-form expression of the upper bound transmission capacity based on the Weber model for the random networks. Finally, we evaluated effects of parameters in the communication range, density, SINR threshold and fading factors, and consequently transmission capacity of the network by sensitivity analysis. The numerical simulation showed that the optimum density of nodes was existed to obtain the upper bound transmission capacity. The capacity increased firstly and then decreased over the density of nodes increasing. It affected by channel fading factor and communication range sensitively.
Traffic modeling is a key step in several intelligent transportation systems (ITS) applications. This paper regards the traffic modeling through the enhancement of the cell transmission model. It considers the traffic flow as a hybrid dynamic system and proposes a piecewise switched linear traffic model. The latter allows an accurate modeling of the traffic flow in a given section by considering its geometry. On the other hand, the piecewise switched linear traffic model handles more than one congestion wave and has the advantage to be modular. The measurements at upstream and downstream boundaries are also used in this model in order to decouple the traffic flow dynamics of successive road portions. Finally, real magnetic sensor data, provided by the performance measurement system on a portion of the Californian SR60-E highway are used to validate the proposed model. 相似文献
There is not a widely amount of available annotated Arabic corpora. This leads us to contribute to the enrichment of Arabic corpora resources. In this regard, we have decided to start working with correct and carefully selected texts. Thus, beginning with the Quranic Arabic text is the best way to start for such an effort. Furthermore, the annotating linguistic resources, such as Quranic Corpus, are important for researchers working in all Arabic natural language processing fields. To the best of our knowledge, the only available Quranic Arabic corpora are from the University of Leeds, University of Jordan and the University of Haifa. Unfortunately, these corpora have several problems and they do not contain enough grammatical and syntactical information. To build a new Corpus of the Quran, the work used a semi-automatic technique, which consists in using the morphsyntactic of standard Arabic words “AlKhalil Morpho Sys” followed by a manual treatment. As a result of this work, we have built a new Quranic Corpus rich in morphosyntactical information. 相似文献
In the present work the effect of the chemical reaction on the temperature field in an anode supported planar SOFC is numerically studied by the aid of a two-dimensional mathematical model. For the model development the mass transport phenomena, the energy conservation, the species flow governed by Darcy’s law and the electrochemistry are coupled. The finite difference method is used to solve numerically the system of the equations.The temperature field within each component of the SOFC (interconnection, cathode, anode and electrolyte) is calculated via the mathematical model which is implemented in FORTRAN language. The model results demonstrate the effect of different expressions of the chemical heat source, expressed in terms of enthalpy and entropy, on the temperature field and the location of the higher temperatures that occur within the SOFC during its operation. 相似文献