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Soldier Radio Waveform (SRW) network is a kind of mobile Ad hoc network. It is mostly suitable to tactical or emergency communications. The Time Division Multiple Access (TDMA) control mechanism of Barrage Relay Network (BRN) is used in SRW. To make simulation study on BRN, a group of network models, node models, and process models of BRN are built with OPNET simulation kits. Moreover, the simulation study includes Controlled Barrage Region (CBR), which is a representative application of BRN. The procedures of building CBR and data transmission are implemented. The correctness of these models is proved by extensive simulation experiments and rigorous analyses. These models can be used in both academic study and industrial applications.

The scheme of maglev-rotor unmanned aerial vehicle (UAV) is presented based on research of the existing multi-rotor UAV with vertical take-off and landing (VTOL) capability in this paper. Besides calculation and CFD analysis of aerodynamic characters of the maglev-rotor system and the transition between the VTOL mode and the forward flight mode of the maglev-rotor UAV, test flight are carried out to verify the calculation method and the feasibility of the scheme. The prototype of conventional electric motors is specially designed and built on this purpose. The attack angle of fuselage, the tilt angle of rear duct, the power of lift duct and the power of rear tilt duct are measured at different wind speeds. It is confident that the transition mode is available since the changes of the fundamental parameters, such as the attack angle of fuselage, the power of the lift duct fan and the rear tilt duct fan, the tilt angle of the rear duct fan, go on smoothly and continuously.

This paper presents a coded aperture method to remotely estimate the radioactivity of a source. The activity is estimated from the detected counts and the estimated source location, which is extracted by factoring the effect of aperture magnification. A 6mm thick tungsten-copper alloy coded aperture mask is used to modulate the incoming gamma-rays. The location of point and line sources in all three dimensions was estimated with an accuracy of less than 10% when the source-camera distance was about 4 m. The estimated activities were 17.6% smaller and 50.4% larger than the actual activities for the point and line sources, respectively.

Uranium enrichment measurement is an essential quality inspection for fuel rods before delivery to users. Generally, compared with active neutron assay (ANA) equipment, passive gamma-ray assay (PGA) equipment is more economical and safer. However, the current PGA equipment based on photomultipliers is too slow (1 m/min) to meet the growing needs in China. Recently, we have developed a set of compact high-speed PGA equipment including four detection modules (128 units in total), a 128-channel data acquisition system (DAS), a power supply, special software, and an automatic loading and unloading mechanism. The detection unit is based on silicon photomultipliers in virtue of its compact size and good performance. The DAS processes signals of all units in parallel into a sequence of data packets carrying the energy information and the corresponding unit ID. The software integrates the data packets into a fluctuating count curve in a time-delay superposition method and identifies possible abnormal pellets. After calibrations, our equipment can locate abnormal pellets accurately at a speed of 6 m/min. In addition, it can directly measure the enrichment of fresh pellets not in secular equilibrium without waiting for two months. So far, the equipment has been successfully run for one year on the assembly line of China North Nuclear Fuel Co. and shows good potential to replace the traditional ANA equipment.

We develop a compact, high signal-to-noise ratio line-detector array Compton scatter imaging system based on Y2SiO5 scintillators and silicon photomultipliers. It is shown that the system's response uniformity is better than 98% for low-Zeff materials after a specific correction. Backscatter images of an “IHEP”-character model, cubes of different materials, and some other applications are presented, to show its potential for use in nondestructive testing.

The seeds of Gleditsia sinensis and Gleditsia microphylla, widespread in China, are an important source of galactomannans. G. sinensis gum (GSG) and G. microphylla gum (GMG) were purified and precipitated using different concentrations of ethanol and isopropanol. The GSG and GMG, precipitated in different stages, presented different characteristics, including polymer recovery, mannose/galactose ratio, chemical composition, molecular weight, and morphological appearance. The galactomannan recovery of GSG and GMG in 33.3% ethanol was 81.7% and 82.5%, respectively, while that in 28.8% isopropanol was 81.3% and 82.9%, respectively. To achieve similar precipitation efficiency, the amount of isopropanol should be lower than that of ethanol because of the lower dielectric constant of isopropanol (20 vs. 25 for ethanol). The precipitation behavior of galactomannans in polar organic solvents was dependent on the molecular structures and properties of the solvent. A higher mannose/galactose ratio and a higher molecular weight was obtained in a lower concentration of alcohols.

Neutron localization, which finds (localizes) neutron sources , is a non-destructive method used in the application of nuclear emergency response and special nuclear material (SNM) localization. Fast neutrons from SNM fission can be detected using a hydrogen-rich scintillation detector system with relatively high efficiency. In this study, we proposed a compact multi-pixel photon counter (MPPC)-based neutron scattering camera prototype consisting of sixteen plastic scintillator pillars. This camera is capable of detecting fast neutrons produced by neutron sources in the far-field. It provides a three-dimensional structure to detect incident neutrons with omnidirectional (4 π ) field-of-view. Based on double neutron–proton elastic scattering, a reconstructed image can be achieved by using an Am–Be source. Besides, time-of-flight technology was adopted for separating neutron signals from the gamma-ray background radiation. The results of the imaging efficiency and the average imaging resolution are reported in this article. This camera offers good prospects to expand the application field of SNM localization for nuclear security and proliferation deterrence.

A new signal readout method for position-sensitive multi-output detectors, such as those in high-energy spectroscopy measurement and nuclear imaging, was developed by combining the charge division circuit, summing circuit and charge-to-time conversion (QTC) circuit. The 64 outputs of a Hamamatsu H8500 position-sensitive photomultiplier tube were processed, and three digital pulses were generated. The widths of digital pulses were determined using the time-to-digital converter in an field programmable gate array. The energy and position information of incident γ-rays is estimated based on the proportionality between the width of digital pulses and input charge created by γ-photons. A prototype was built using discrete components and tested, and the energy and position resolutions were improved compared with that obtained with standard ADCs. This method greatly simplifies the front-end electronics and the digital interface. It enables a compact electronics system and an easy integration into an ASIC.

With the development of information technology, the automation level of electric engineering is continuously increasing. The extensive application of the PLC technique has enhanced the control effect. During the application process of the PLC technique, CPU plays a fundamental role, efficiently improving the control flexibility and reliability. In this paper, the PLC technique is introduced, based on which its application to electric engineering automation is discussed.

A PET module that comprises a pair of compact, high-resolution and large-area detectors based on silicon photomultipliers (SiPM) was developed and evaluated. The detector's effective area was 24 mm x 24 mm. LYSO crystals measuring 1.9 mm x 1.9 mm x 10 mm and charge division circuit were employed to obtain high spatial resolution with relatively concise Front-end electronics (FEE). Initial results showed the detector to be compatible with 1.5 T magnetic fields. The system's intrinsic FWHM spatial resolution is 1.50 mm. The average energy resolution is 18.5% and the coincidence timing resolution is 2.6 ns. (C) 2011 Elsevier B.V. All rights reserved.