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This paper discusses the thermal management of the structure design of an anti-freezing building in an HVDC substation. The CFD simulation has been carried out under the condition of natural wind velocity with the influence of the air cooler. The result shows that the hot air reflux ratio is proportional to natural wind velocity when the anti-freezing building has a certain height; the hot air reflux ratio is proportional to the anti-freezing building height when the natural wind is in a certain velocity. Through detailed cost analysis, the most optimal height of anti-freezing building is about 6 meter. Based on the thermal analysis, rational design of anti-freezing building can effectively prevent hot air recirculation, and the air cooler inlet temperature decreases 3°C.

A micro-pattern gas detector named leak microstructure (LM) has been studied. A new chemical electrolytic technique is introduced to make perfect shaped LM needles with very sharp tips, and this method may be developed to make LM array detectors in batches. The experimental results are presented for both a single needle LM detector and a small LM array detector. The gas gain is up to 105 by calculation from the waveform. Good gain stability and uniformity are achieved. The light emission from the needle tip is also measured in Ar/CF4(95/5) gas mixture. The result shows a promising application for imaging.

Silicon photomultipliers (SiPMs) are a new generation of semiconductor-based photon counting devices with the merits of low weight, low power consumption and low voltage operation, promising to meet the needs of space particle physics experiments. In this paper, comparative studies of SiPMs and traditional vacuum photomultiplier tubes (PMTs) have been performed regarding the basic properties of dark currents, dark counts and excess noise factors. The intrinsic optical crosstalk effect of SiPMs was evaluated.

A kind of thick GEM-like gaseous electron multiplier (THGEM), which is mechanically an expansion of the GEM with its various dimensions being enlarged, is studied. The leak current of THGEM plates is measured. The effective gain and energy resolution of a single THGEM are studied with a source of 55Fe, and the effective gain of the single THGEM versus the electric field strength in the induction region is investigated. The results show that the leak current of THGEM plates is less than 200 pA. In an atmospheric-pressure standard gas mixture, 8×103 effective gain and about 32% energy resolution can be reached for the single-THGEM detector.

The BESⅢ detector has a high-resolution electromagnetic calorimeter which can be used for low momentum μ-π identification. Based on Monte Carlo simulations, μ-π separation was studied. A multilayer perceptron neural network making use of the defined variables was used to do the identification and a ...

The CsI(Tl) crystal modules of the Beijing Spectrometer III (BESIII) electro-magnetic calorimeter (EMC) were designed and assembled through Monte Carlo simulation and experiments. After the assembly was finished, the performance of each crystal module was tested by cosmic rays. All crystal modules were found to work well before the installation of EMC.

The nanostructured materials have been revealed to have exclusive physical and chemical properties due to their quantum-size effects, small-size effects and a large fraction of grain boundaries. Especially, the grain boundaries play an important role in the electrical resistivity of nanostructured metal. We use the four-point probe method to measure the values of electrical resistivity () of the nanostructured aluminum samples and the coarse-grained bulk aluminum samples at temperature (T) ranging from 8 K to 300 K to explore the relationship between the electrical resistivity and temperature. The aluminum nanoparticles produced by the flow-levitation method through electromagnetic induction heating are compacted into nanostructured samples in vacuum by the hot pressing and sintering technology. The microstructures of all nanostructured aluminum samples are analyzed by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope with the energy-dispersive spectrometer (SEM-EDS). The densities of all nanostructured aluminum samples are measured by using the Archimedes method (the medium is absolute alcohol). The experimental results show that the shape of aluminum nanoparticles is found to keep spherical from the SEM images and the relative density of all nanostructured aluminum samples is about 93% of the coarse-grained bulk aluminum. The XRD spectra state that the face-centered cubic (fcc) phase dominates the samples and no diffraction peak related to impurities appears in the XRD spectrum for each of all nanostructured aluminum samples. Amorphous alumina layers (about 2 nm thick) are found to surround the aluminum nanoparticles and hence connect the grains in the nanostructured aluminum as shown in the high-resolution TEM images. Owing to the scattering of grain boundaries on electrons and the phonon-electron scattering at grain boundaries, the electrical resistivity is far larger in the nanostructured aluminum than in the coarse-grained bulk aluminum and the relationship between the electrical resistivity and temperature for nanostructured aluminum shows a different feature from that for the coarse-grained bulk aluminum. Although the temperature dependent electrical resistivity ((T)) is a function of T4 at low temperatures for the coarse-grained bulk aluminum, it varies with the temperature not only according to the relation T4, but also according to the relation T3 for the nanostructured aluminum. The residual resistivity (0) of the nanostructured aluminum sample is about 5.510-4m, 5-6 orders magnitude larger than that of the coarse-grained bulk aluminum (2.0110-10m) due to the scattering of both the grain boundaries and amorphous alumina on electrons therein.

Mobile communication network echo is mainly caused by two factors: mobile terminals and wireless network delay. Several adaptive algorithms are found to offset the echo of wireless network delay, such as the LMS-type algorithm (including the NLMS, BLMS), and RLS algorithms. By analysis and comparison of their performances, a new algorithm (NLMS-BRLS) is obtained for echo cancellation in mobile communication systems, and the simulation results demonstrate the efficiency of the proposed method.

In this paper, we proposed a new mixed variable step size ELMS algorithm (MVSS-ELMS) which combined the mean square error and the correlation of the error to modify the step size. The approach is general in the sense that it not only retains the benefits of ELMS algorithm lower steady-state error, but also improves the system convergence speed. In comparison, the new approach performance is much better than VSS-ELMS algorithm and VFSS-ELMS algorithm in the convergence speed and anti-noise capacity. Effectiveness of the proposed algorithm is demonstrated through computer simulations.

In order to overcome the shortcoming of fixed step- size constant module(CM) blind equalization algorithm, this paper proposes an new adaptive variable step- size constant module blind equalization algorithm, in which we use mean square error (MSE) to improved function as step- size control factor. Computer simulations and theory analyses show that the proposed algorithm has advantages of low complexity, fast convergence, and low computational load.

In the modern times, the highway management needs better information supporting system to connect all these Online Transaction Processing Systems, to meet the integrated data analysis need of scientific management. Because of the deficiencies of traditional data management information system, the data warehouse technology has been used to organize and analysis the massive datas and provide a basis decision-making supporting. Combination of the highway management practices, in this paper the provincial highway management data warehouse architecture was constructed and the data model design method and strategy were put forward, and the subject, data granularity of data warehouse for highway management were analysised. In finally the meta-data organize and its implementation program were discussed. With the application of data warehouse technology in highway management, which will promote the analysis of management decision-making of China's highway modernization, scientific and information process.

In wireless communications, blind equalization plays an important role in combating inter-symbol interference (ISI) introduced by multipath fading wireless channels, and its main performance criterions are residual mean square error (MSE), convergence speed, and complexity. In this paper, an efficient blind decision feedback equalization algorithm suitable for wireless communication channels is proposed. The performance of the new method is compared to traditional blind decision feedback algorithm by means of computer simulations, and the simulation results confirm the validity of the proposed method.

Aiming to overcome deficiencies of existing DSS for VRP, which cannot meet with real-time and online routing and scheduling, a new knowledge representation approach to efficiently eliciting domain knowledge of the vehicle routing problems (VRP) and transforming this elicited knowledge into a machine usable format is proposed. According to the characteristics of VRP, the approach contains three steps: confirming problem rarr identifying problem structure rarr representing problem knowledge. The approach is demonstrated in detail through case study after analyzing principles of it. This approach sets foundations for consequent modeling and solving of VRP and can be used as reference by DSS for any types of VRP