In this paper, the spatial correlation analysis was based on a circular antenna arrays. The antenna was placed on the circle equably. So, the distance between antenna elements was considered in the analysis. At the same time, the formula of spatial correlation at the receiver was educed, which was aimed at circular antenna arrays. The correlation between antenna elements changed due to the changed antenna distance, the angle spread and the average angle of arrival direction of the signal. The antenna correlation changed with the angle spread changed. At this paper, the equality distributing of angle spread was considered. Each parameter that influenced spatial correlation was analyzed, the simulation figure demo the results derived by the formula. It was important to the analysis of the MIMO systems estimation and design.Keywords: multiple input multiple output (MIMO) system, spatial correlation, angle spread, direction of signal arrival, antenna array 1-4244-1312-5/07/$25.00

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The chemical composition and antioxidant activity of extracts (POE) of Penicillium oxalate isolated from Ligusticum chuanxiong Hort have been investigated. However, the biological activity of POE is limited, and its antioxidant, stress resistance and DNA protection effects in vivo are unclear. The current study aims to explore the beneficial effects of POE on DNA damage protection in pBR322 plasmid and lymphocytes and stress resistance in Caenorhabditis elegans. The results showed that POE increased the survival rate of C. elegans under 35°C, UV and H2O2 stress, attenuated ROS and MDA accumulation, and enhanced the activity of some important enzymes (SOD, CTA, and GSH-PX). In addition, the POE-mediated stress resistance involved the upregulation of the expression of the sod-3, sod-5, gst-4, ctl-1, ctl-2, daf-16, hsp-16.1, hsp-16.2, and hsf-1 genes and acted dependently on daf-16 and hsf-1 rather than skn-1. Moreover, POE also reduced lipofuscin levels, but did not prolong the lifespan or damage the growth, reproduction and locomotion of C. elegans. Furthermore, POE showed a protective effect against DNA scission in the pBR322 plasmid and lymphocytes. These results suggested that P. oxalate extracts have significant anti-stress and DNA protection potential and could be potential drug candidates in the pharmaceutical field, thus greatly broadening the understanding of the biological effects of the endophytic fungus P. oxalate.

SPM (Scanning Probe Microscope) provides "three-dimensional images" with nanometer level resolution, and some of them can be used as metrology tools. However, SPM's images are commonly distorted by non-ideal properties of SPM's piezoelectric scanner, which reduces metrological accuracy and data repeatability. In order to eliminate this limit, an "open-loop sampling" method is presented. In this method, the positional values of sampling points in all three directions on the surface of the sample are measured by the position sensor and recorded in SPM's image file, which is used to replace the image file from a conventional SPM. Because the positions in X and Y directions are measured at the same time of sampling height information in Z direction, the image distortion caused by scanner locating error can be reduced by proper image processing algorithm.

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In order to understand the loading path and further anticipate the bearing capacity of the staggered perforated RC flanged shear walls, this paper proposed an improved strut-and-tie model and perforated reduction coefficient based on the theoretical and numerical analysis. The finite element model has been validated experimentally. The parametric study was conducted numerically to investigate the influence of shear-span ratio, axial compression load ratio, flange, dimension of perforation, and the additional rebar on the seismic performance of shear walls. When the ratio of perforation area to the wall is ranged from 10% to 26%, the proposed strut-and-tie model can effectively predict the loading path and the lateral ultimate bearing capacity with the different combinations of shear-span ratio and axial compression load ratio; however, if the ratio of the perforation area is either lower than 10% or higher than 26%, the proposed strut-and-tie model is not applicable. While the perforated reduction coefficient can be used to calculate the lateral ultimate bearing capacity of the perforated shear wall.

Some influence factors such as engine performance, structural characteristics and docking situation affect the operating performance and structural safety of vehicle. However, due to lacking of systematic workflow in current vehicle manufacturers, it's unsatisfactory for engine selection and docking. In this paper, a vehicle engine configuration procedure was systematically designed based on the integrative structure, and a comprehensive study combined with engine selection of a vehicle model and the process of docking design was made. Analysis and demonstration for the key influence factors of various stages were made by applying examples, and solutions were proposed, which provide references for the future development of new automobile samples.

LBSNs (Location-based Social Networks) provide abundant information for users to browse and explore the places where they are interested in, named POI (Point-of-Interest). However, such large amount of check-in records in LBSNs cause information overload problem and increase difficulty for users to find the really desire POIs. POI recommendation systems can be employed to solve this problem. Most traditional POI recommendation methods are CF (Collaborative Filtering) based and achieve recommendations for a particular user according to check-in records of his similar users. In this paper, we propose an adaptive CF based algorithm to achieve POI recommendations for users, considering their personalized activity regions. Compare with existing algorithm, our algorithm does not construct user-POI matrix by using the entire historical records. Instead, we first explore users' activity regions and construct more personalized user-POI matrix for each particular user according to corresponding activity regions. Besides, we propose a method to dynamically determine the number of similar users for a certain user, instead of using a fix number for all users, leading to more personalized recommendations. We have implemented our POI recommendation system and compared with state-of-theart methods by using Foursquare dataset. The experimental results show that our POI recommendation system achieves better performance than all these compared approaches.