In this paper, 7 different samples and two radioactive isotopes ( 60 Co and 137 Cs) are used to fill a standard industrial waste bucket for simulating the real situation of drummed nuclear wastes. A transmission tomographic gamma scanning (TGS) measurement is carried out based on the TGS system independently developed by the project group for transmission image reconstruction. The data is processed by the MLEM iterative algorithm, it's able to reconstruct the actual distribution of inhomogeneous media within the drum and to correct attenuation coefficients values of media under particular emission energies. The results show: the MLEM iterative algorithm can reconstruct clear TGS transmission images with accurate resolution of different densities which accord with the actual distributions of inhomogeneous media within the drum; the quality of reconstructed images tend to improve with the increase of transmission energy; the corrected attenuation coefficients values of 72 voxels within the drum under emission energy:661.661keV, 1173.238keV and 1332.513keV are consistent with the reference values, which proves the validity of this method.

In recent years, with the rapid development of micro electro mechanical system and DSP in high operation speed and low power consumption and high polymer lithium battery, all this creates the conditions for the development of micro unmanned aerial vehicles. UAVs possess the advantages of simple structure, flexible flight, the capability of vertical takeoff and landing, great passing ability, better carrying capacity, and so on. They can be used widely in various fields such as disaster emergency and rescue, urban mapping, outdoors exploration. The unmanned quadrocopter aroused interest among those scholars for itspotential application prospect and value in use. This paper briefly summarizes the history of application and development of the unmanned quadrocopter, and reviews the new algorithm and progress in the study of the unmanned quadrocopter and application of the unmanned quadrocopter at home and abroad.

This work presented the design and implementation of a wireless acquisition system for seismic signal. 4 distributed signal acquisition stations were integrated to the low-power prototype which composed of 48 acquisition channels, and a star-shaped wireless network was built which is suitable for seismic data transmission using the networking mode of multi-pipe and multi-address switching. A distributed seismic data acquisition system was accomplished which has the function of synchronous control and asynchronous transmission. The key technical problems and solutions of time balance distribution between multi-channel time-sharing switching acquisition and temporary storage, and wireless seismic data transmission is analyzed in detail in this paper. Thus the additional accessories of traditional wired seismograph were greatly reduced, to improve its cable layout trouble and low efficiency of construction in an adverse environment. This system increased efficiency more than 50% and took same exploration effect compared with wired mode in the field application.

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This paper aims at the problem that how to elimination the DC component of the MEMS geophone in the acquisition and processing of Seismic signal. Put forward to design a new circuit in the signal handing system. Design a new type of DC elimination circuit to eliminate the DC component through low-pass filter, reverse and other modules. The experiment result shows that, this new DC elimination circuit is easier to realize and has a large advantage than other existing DC elimination circuits.