Strain Transfer Mechanism of Grating Ends Fiber Bragg Grating for Structural Health Monitoring

The grating ends bonding fiber Bragg grating(FBG)sensor has been widely used in sensor packages such as substrate type and clamp type for health monitoring of large structures.However,owing to the shear deformation of the adhesive layer of FBG,the strain measured by FBG is often different from the strain of actual matrix,which causes strain measurement errors.This investigation aims at improving the measurement accuracy of strain for the grating ends surface-bonded FBG.To fulfill this objective,a strain transfer equation of the grating ends bonding FBG is derived,and a theoretical model of the average strain transfer from the matrix to the optical fiber is developed.Moreover,parameters that influence the average strain transfer rate from the matrix to the optical fiber are analyzed.A selection scheme of bonding parameters by numerical simulation is provided,which is significantly advantageous over that of the grating bonding FBG.The theoretical equation is verified by finite element method(FEM).Compared with the existing model,the proposed model has higher measurement accuracy.Experimental tests are performed to validate the effectiveness of the proposed model on the equalintensity cantilever beam,whose surface is attached to the bare FBG with grating ends bonding and strain gauge by using epoxy glue.The results show that there is a great agreement between the outcome of the bare FBG and that of the strain gauge,and the corrected strain is closer to the true strain.The proposed model provides a theoretical basis for the design of the grating ends surface-bonded FBG strain sensor for health monitoring of large structures.

The association between the genetic polymorphisms of LMP2/LMP7 and the outcomes of HCV infection among drug users

Objective：To investigate a possible association of LMP2/LMP7 genes with chronic hepatitis C virus（HCV） infection,and to assess whether LMP2/LMP7 genes could influence the outcomes of HCV infection among drug users.Methods：Genomic DNAs of 362 anti-HCV sero-positive drug users and 225 control drug users were extracted from the peripheral blood leukocytes.The sero-positive patients were divided into those who had persistent infection and those who had spontaneously cleared the infection.Polymorphisms of LMP genes were determined by PCR combined with restriction fragment length polymorphism（RFLP）.Results：The distribution of LMP2 genotypes among the control,persistent infection and spontaneous clearance groups were not different.However,the LMP7 codon 145 Gln/Lys,Lys/Lys,and Gln/Lys＋Lys/Lys genotypes were found significantly more frequent in the persistent infection group than in control group（OR=1.75,95%CI=1.06～2.90;OR=3.16,95%CI=1.23-8.12;OR=1.94,95%CI=1.21-3.12,respectively）.Similarly,the frequencies of the codon 145 Gln/Lys,Lys/Lys,and Gln/Lys＋Lys/Lys genotypes were found significantly more frequent in the persistent infection group than in the spontaneous clearance group（OR=1.64,95%CI=1.04-2.57;OR=2.40,95%CI=1.09-5.28;OR=1.76,95%CI=1.152.69,respectively）.Stratified analysis indicated that combined genotype Gln/Lys＋Lys/Lys of the LMP7 gene was related to an increasing susceptibility to HCV infection（OR=1.91,95%CI=1.02-3.55;OR=2.19,95%CI=1.243.89;OR=1.91,95%CI=1.05-3.48,OR=2.86,95%CI=1.41-5.78,respectively）and the risk of persistent HCV infection（OR=1.94,95%CI=1.12-3.34;OR=2.02,95%CI=1.21-3.38;OR=1.78,95%CI=1.12-2.85,OR=2.23,95%CI=1.09-4.58,respectively）among30-year-old,males,the injection drug user（IDU）subjects and/or the shorter duration drug users（≤5 y）.Conclusion：These results suggest that polymorphism of the LMP7 gene may have an influence on the outcomes of HCV infection,and is one of the factors accounting for the genetic susceptibility to HCV infection among drug users.

Sensor Layout of Hoisting Machinery Vibration Monitoring Based on Harmony Genetic Search Algorithm

With the construction of automated docks,health monitoring technology as a parallel safety assurance technology for unmanned hoisting machinery has become a hot spot in the development of the industry.Hoisting machinery has a huge structure and numerous welded joints.The complexity and nonlinearity of the welded structure itself makes the structural failure parts random and difficult to arrange for monitoring sensors.In order to solve the problem of effectiveness and stability of the sensor arrangement method for monitoring the structure of hoisting machinery.Using the global and local search capabilities enhanced by the complementary search mechanism,a structural vibration monitoring sensor placement algorithm based on the harmony genetic algorithm is proposed.Firstly,the model is established for modal analysis to obtain the displacement matrix of each mode.Secondly,the optimal parameter combination is established through parameter comparison,and the random search mechanism is used to quickly search in the modal matrix to obtain the preliminary solution,and then the preliminary solution is genetically summed The mutation operation obtains the optimized solution,and the optimal solution is retained through repeated iterations to realize the decision of the vibration sensor layout of the crane structure monitoring.Combining the comparison test of harmony genetic algorithm,harmony search algorithm and genet-ic algorithm,the fitness of harmony genetic algorithm in X,Y and Z directions were 0.0045,0.0084 and 0.0058,respectively,which were all optimal.And the average probability of deviating from the optimal path is 1.10%,19.34%,and 54.43%,which are also optimal.Harmony genetic algorithm has the advantages of simplicity,fastness and strong global search ability,and can obtain better fitness value and better search stability.

结构健康监测与完整性管理

在中国经济快速发展的今天，大型结构装置和设施扮演着越来越重要的角色，在推动国民经济建设中发挥着不可替代的作用。如何保障这些结构装置或设施使用过程中的安全，如何在保证这些结构装置安全地发挥最大作用的同时延长其使用期限，都是摆在科研工作者和工程人员面前的重要问题。