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In shallow water, there exist regular interference striations on the structured sound intensity pattern versus frequency and element location of a horizontal array. Beamforming along the striation with frequency-shifted pressure can improve the correlation among array signals, but the beam focusing performance is limited by the source spectrum (e.g. random phase spectrum generated from ship-radiated noise) and signal truncation. In this paper, the cross-correlation phase relationship among the array signals is deduced, and striation-based beamforming with such cross-correlated data can produce a similar directivity to the conventional beamforming, while the effect from signal truncation and source spectrum can be eliminated. This striation-correlation-based beamforming also outputs the signal corresponding to the Green’s function between the source and the reference array element, moreover, recovers the interference structure that characters the channel. The striation-based array signal processing also provides the proposed Greens function estimation method with the ability to work effectively under the condition of low signal-to-noise ratio. Simulation results are presented and performance variations related to signal frequency, signal-to-noise ratio, striation slope estimation error, element number and array aperture are also analyzed numerically.

Due to the dispersion of normal modes in shallow water, there exist regular striations on the interference spectrogram in space-frequency domain. Based on the range-frequency domain striations, waveguide invariant can be estimated with the prior knowledge of source range. Utilizing striations along the array, Rouseff and Zurk [J. Acoust. Soc. Amer. 130 (2011) EL76–EL81] proposed the striation-based beamforming (SBF), which shows a theoretical possibility to estimate waveguide invariant that is independent of source range. To make this beamforming technique more practical, its application requirements and performance limitation should be defined. These two issues are researched with the phase and amplitude relationships deduced by the frequency-shift compensation theory. It shows the source whose spectrum varies slowly and received signals that contain the complete information of transmission time are keys for applying SBF to real work. The azimuth limitation can lead to the degradation of array gain and distortion of interference structure. Matching parameters of waveguide invariant and source range, respectively, two modified striation-based beamformers are developed to eliminate the azimuth limitation. Simulation and experimental results are presented.

A low tower cable-stayed bridge with a span of 30m+60m+120m+60m+30m had been built before Guidelines for Seismic Design of Highway Bridge was promulgated. Because of its impor¬tance and specificity, it is necessary to do research on seismic performance of this bridge. According to the numerical analysis, it is found that the structural response exceeds the allowance and the bridge might be destroyed if earthquake happened. Here, energy dissipated technology is chosen to cope with this problem. But traditional lead shear damper hasn’t the capabilities of large deformation for some reason and can not be applied to bridge engineering in general case. In this article, a new type of lead shear damper with capabilities of large deformation is used to achieve energy dissipation. Through comparing, it is found that the damping effect of this new damper is as good as that of viscous damper. And the damper has no problem with leakage and metamorphism. What’s more, it is much cheaper than vis¬cous damper. So, lead shear damper has a good prospect in bridge damping.

At the beginning of the 21st century, Su-tong and Stonecutters cable-stayed bridges were born into the world, which make the original span record of 890m up to 1088m. The increasing range of the span is so large that it is necessary to carry out a special research on structural system of the cable-stayed bridge with kilometer-scale span. Therefore, two cable-stayed bridges have been designed as the research objects, which come from the background of Su-tong cable-stayed bridge. And the main span is respectively 1308m and 1500m. In this paper, an analysis is carried out from the aspect of girder-tower relationship which comes from the concept of the structural system. In the static analysis, structural system, which is respectively floating, half floating and rigid, has been studied. And in the dynamic analysis, the girder-tower relationship has also been studied, which is respectively with no dampers, elastic links and viscous dampers. Based on the analysis results, structural system applicable for kilometer-scale cable-stayed bridges is summarized.

For a super-long-span cable-stayed bridge, it is often required that the main tower be essentially elastic under a strong earthquake. Therefore, a seismic isolation structural system is often used to reduce the seismic response. Since the seismic displacement at the end of the deck may severely exceed the allowance, the elastic link device and viscous damper are often employed to control the displacement. In this article, a new damper (Metal Alloy Brace) is used to achieve this goal. Under the frequently occurred earthquake excitation, MAB’s hysteretic curve is plump, so the structural deformation is reduced. Under rare earthquake excitation, MAB can supply so big stiffness that the structural deformation is limited, and the damper will also dissipate much energy. And the damper has no problem with leakage and metamorphism. So, the prospect of MAB is brightening.

With the development of society and economy, the issues of environment have becoming the focus of all around the world, especially in the developing countries. In China, on one hand, villagers' income was rising. On the other hand, the environment was running down gradually: In 2009, pesticides were used by 89% of farmers. Upon 300,000 tons of pesticides were used in the whole country annually. And 60~70% of pesticides were dissolved in waters and soils; 67% of daily rubbishes were discarded arbitrarily by villagers in country; 74% of farmers made use of plastic film, while only 13% of it was cleared completely; the decrease of forest areas that due to the denudation was almost 50% compared with the last 5 years; in villages, many resources were not effectively used. 64% of the villagers did not re-use waste consciously. It can be concluded that protection of the ecological environment in rural areas was urgent. As a sample writer took an investigation in a village.

Oxygen of two propionic acid groups of the heme group in an MP-8 molecule, leading to an increase in the non-planarity of the porphyrin ring of the heme group. The increasing extent in the non-planarity of the porphyrin ring of the heme group due to the interaction of La3+ and MP-8 molecule would be significantly decreased because NaCl could increase the aggregation extent of MP-8 molecules. Although methanol can reduce the aggregation extent of MP-8 molecules, it has little influence on the increasing extent in the non-planarity of the porphyrin ring of the heme group due to the interaction of La3+ and MP-8 molecule.