Robustness Analysis of a Flexible Cable-Strut Tensile Structure

Lian-meng Chen,Wei-feng Gao,Zhichao Jiang,Yi-yi Zhou,Fu-bo Zhang,Shi-lin Dong 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.5

Currently, the robustness analysis of structure is primarily related to rigid structures, and little has been done to study the robustness of spatial fl exible cable-strut tensile structures with larger span, more complex forms, lower redundancy, more sensitivity to unexpected interference such as construction deviations, etc. Based on the H ∞ theory, this paper starts with the fundamental theory and develops analysis method for the robustness of fl exible cable-strut tensile structures, and then the relationships between the structural robustness and some design parameters such as initial pre-stress level, load distribution form, structural span, cross-section area, rise-span ratio, etc. are analysed through a case study of a concrete cable-strut tensile structure in China. On this basis, the eff ects of construction errors such as element-length error and supporting node position error are further analysed. Finally, the importance of each kind of element is analysed by means of conceptual removal of element. The results show that the higher the initial pre-stress level, the larger the element cross-section, the smaller the structural span, the larger the rise-span ratio and the more uniform the load distribution, the stronger the structural robustness. In the limited construction error range, the element-length error and the supporting node position error have little eff ects on the robustness of the structure. The hoop cables are the more important elements and the elements in inner region of the structure are of comparatively lower importance in the cable dome structure in this study.

Identification and Adjustment of the Pretension Deviation in Cable-Strut Tensile Structures

Lian-meng Chen,Zhichao Jiang,Wei-feng Gao,Yi-yi Zhou 대한토목학회 2020 KSCE Journal of Civil Engineering Vol.24 No.1

Construction errors inevitably arise in real cable-strut tensile structures. Nevertheless, construction error analysis and evaluation, as well as methods to identify the source of the errors and proper adjustment methods to compensate for these errors, remain in their infancies. In this study, the relationship between pretension deviation and element length deviation is first established based on the three basic equations for pin-joint structures. On this basis, identification methods are proposed to identify the sources of the pretension deviation caused by the active cable length deviation and the pretension deviation caused by both the active and the passive cable length deviations. Using measured data, an adjustment method is developed for the pretension deviation under different scenarios. Furthermore, the effectiveness of the adjustment method for the pretension deviation is discussed using the evaluation indices. Finally, a case study is presented and demonstrates that the proposed identification method can identify the sources of the pretension deviations. The number of adjusted cables will affect the level of adjustment for the pretension deviation. During the adjustment of the pretension deviation, different adjustment methods will result in different shape deviations and different maximum displacements.

Determination of a Monitoring Scheme for Controlling Construction Errors of a Cable-strut Tensile Structure

Lian-meng Chen,Wei-feng Gao,Dong Hu,Yi-yi Zhou,Fu-bo Zhang,Shi-lin Dong 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.10

Construction errors are inevitable in real cable-strut tensile structures. Nevertheless, the relevant work, especially the monitoring scheme design work, to control the construction errors is lacking. At present, the monitoring schemes always lay out the monitored members in the places with great internal force or great deformation, do not consider the method to control the construction errors and do not explain the method to lay out the monitored members in fundamental theory. To address this situation, the element length error, which is an important construction error affecting the bearing performance, is considered as the factor variable and the fundamental equation of pre-stress deviation and element length error is derived firstly. Next the methods to express the pre-stress deviation, which are only derived from the active cable length errors or from both the active cable and passive cable length errors, are discussed. After that, based on the condition that the errors can be solved and compensated, the least number of monitored members is determined. Moreover, those members sensitive to cable length deviation of active cables are selected as monitored members. In order to evaluate the effect level caused by passive cable length deviation, two evaluation parameters Δ and ρ are further discussed. Finally, one cable-strut tensile structure example is employed to verify the proposed method and the results of the example studies indicate that the least necessary number of monitored members can be achieved for the accurate solution and compensation of active cable length deviations. Different members have different sensitivities to the change of the length in active cables and those members with great sensitivities can be chosen in prior as monitored members. The evaluation parameters Δ and ρ can be used to analyze the source of errors and to evaluate the error effect level caused by the passive cable length deviation.

Optimization of the construction scheme of the cable-strut tensile structure based on error sensitivity analysis

Lian-meng Chen,Dong Hu,Hua Deng,Yu-hong Cui,Yi-yi Zhou 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.5

Optimization of the construction scheme of the cable-strut tensile structure based on error sensitivity analysis is studied in this paper. First, the element length was extracted as a fundamental variable, and the relationship between element length change and element internal force was established. By setting all pre-stresses in active cables to zero, the equation between the pre-stress deviation in the passive cables and the element length error was obtained to analyze and evaluate the error effects under different construction schemes. Afterwards, based on the probability statistics theory, the mathematical model of element length error is set up. The statistical features of the pre-stress deviation were achieved. Finally, a cable-strut tensile structure model with a diameter of 5.0 m was fabricated. The element length errors are simulated by adjusting the element length, and each member in one symmetrical unit was elongated by 3 mm to explore the error sensitivity of each type of element. The numerical analysis of error sensitivity was also carried out by the FEA model in ANSYS software, where the element length change was simulated by implementing appropriate temperature changes. The theoretical analysis and experimental results both indicated that different elements had different error sensitivities. Likewise, different construction schemes had different construction precisions, and the optimal construction scheme should be chosen for the real construction projects to achieve lower error effects, lower cost and greater convenience.

Preparation of High-density YAG/ZrB2 Multi-phase Ceramics by Spark Plasma Sintering

Lian-Meng Zhang,Jie-Guang Song,Jun-Guo Li,Jian-Rong Song 한양대학교 세라믹연구소 2007 Journal of Ceramic Processing Research Vol.8 No.5

ZrB2 and YAG are widely applied because of some excellent properties, but ZrB2 is difficult to prepare as a high-density ceramic, and it is easily oxidized in high temperature air, which limits the application of ZrB2 materials. To obtain high-density for better oxidation resistance ZrB2 ceramic materials, in this paper, Al2O3 and Y2O3 are added into ZrB2 raw material to prepare high-density YAG/ZrB2 multi-phase ceramics by spark plasma sintering. Through the above analysis, it is proposed that 1600oC is regarded as a critical sintering temperature (Tc) to fabricate YAG/ZrB2 multi-phase ceramics. Only if the sintering temperature is higher than Tc, can a nearly full density composite be achieved. The microstructure of sintered YAG/ ZrB2 multi-phase ceramics after 4 minutes at 1600oC is a better compact, the density and relative density are 5.5865 g/cm3 and 99.40% respectively, which indicates that high-density YAG/ZrB2 multi-phase ceramics have been fabricated successfully. ZrB2 and YAG are widely applied because of some excellent properties, but ZrB2 is difficult to prepare as a high-density ceramic, and it is easily oxidized in high temperature air, which limits the application of ZrB2 materials. To obtain high-density for better oxidation resistance ZrB2 ceramic materials, in this paper, Al2O3 and Y2O3 are added into ZrB2 raw material to prepare high-density YAG/ZrB2 multi-phase ceramics by spark plasma sintering. Through the above analysis, it is proposed that 1600oC is regarded as a critical sintering temperature (Tc) to fabricate YAG/ZrB2 multi-phase ceramics. Only if the sintering temperature is higher than Tc, can a nearly full density composite be achieved. The microstructure of sintered YAG/ ZrB2 multi-phase ceramics after 4 minutes at 1600oC is a better compact, the density and relative density are 5.5865 g/cm3 and 99.40% respectively, which indicates that high-density YAG/ZrB2 multi-phase ceramics have been fabricated successfully.

Genetic Variations in TERT-CLPTM1L Genes and Risk of Lung Cancer in a Chinese Population

Zhao, Meng-Meng,Zhang, Yue,Shen, Li,Ren, Yang-Wu,Li, Xue-Lian,Yin, Zhi-Hua,Zhou, Bao-Sen Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.6

Background: This study was conducted to investigate the association between single nucleotide polymorphisms (SNPs) in telomerase reverse transcriptase (TERT) and cleft lip and palate transmembrane1-like (CLPTM1L) and lung cancer risk in a Chinese population. Methods: We performed a hospital-based case-control study, including 980 lung cancer cases and 1000 cancer-free controls matched for age and sex. Each case and control was interviewed to collect information by well-trained interviewers. A total of 5 ml of venous blood was collected for genotype testing of TERT rs2736098 and CLPTM1L rs401681 using TaqMan methodology. Results: The results revealed that the variant homozygote TERT rs2736098TT was associated with an increased risk of lung cancer (OR=2.017, 95%CI=1.518-2.681), especially lung adenocarcinoma (OR=2.117, 95%CI=1.557-3.043) and small cell carcinoma (OR=1.979, 95%CI: 1.174-3.334), compared with the TERT rs2736098CC genotype. Similar results were observed in non-smokers. Conclusion: The TERT rs2736098 polymorphism might affect the susceptibility to lung cancer in Chinese populations. The associations need to be verified in larger and different populations.

Low cycle fatigue properties of hydrogenated welding sheets of Zr–Sn–Nb alloy using funnel-shaped flat specimens

Lian-feng Wei,Chen Bao,Shi-zhong Wang,Yong Zheng,Meng-bin Zhou 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.8

Low cycle fatigue tests on the hydrogenated welding seam of ZreSneNb alloy at room temperature and 360 C had been carried out by using the funnel-shaped flat specimens. The relationships between nominal stress & strain directly measured across the funnel and local stress & strain at the root of the funnel are given by considering cyclic plasticity correction. The results show that the fatigue resistance of welding seam at room temperature is only slightly better than that at 360 C. Probabilistic fatigue life curves are obtained by using a two-parameter power function.

Posterior convergence for Bayesian functional linear regression

Lian, H.,Choi, T.,Meng, J.,Jo, S. Academic Press 2016 Journal of multivariate analysis Vol.150 No.-

<P>We consider the asymptotic properties of Bayesian functional linear regression models where the response is a scalar and the predictor is a random function. Functional linear' regression models have been routinely applied to many functional data analytic tasks in practice, and recent developments have been made in theory and methods. However, few works have investigated the frequentist convergence property of the posterior distribution of the Bayesian functional linear regression model. In this paper, we attempt to conduct a theoretical study to understand the posterior contraction rate in the Bayesian functional linear regression. It is shown that an appropriately chosen prior leads to the minimax rate in prediction risk. (C) 2016 Elsevier Inc. All rights reserved.</P>

Study of the Enhancement of Magnetic Properties of NdFeB Materials Fabricated by Modified HDDR Process

Meng Fu,Fa-zeng Lian,Ji-jie Wang,Wen-li Pei,Yu-lan Chen,Hong-cai Yang 한국자기학회 2004 Journal of Magnetics Vol.9 No.4

The HDDR (Hydrogenation-Disproportionation-Desorption-Recombination) process is a special method to produce anisotropic NdFeB powders for bonded magnet. The effect of the modified HDDR process on magnetic properties of Nd₂Fe₁₄B-based magnet with several composition Nd_(11.2)Fe_(66.5-x)Co_(15.4)B_(6.8)Zr_(0.1)Ga_x (x = 0~1.0) and that of microelement Ga, disproportional temperature and annealing temperature on jHc, grain size were investigated in order to produce anisotropic powder with high magnetic properties. It was found that modified HDDR process is very effective to enhance magnetic properties and to fine grain size. The addition of Ga could change disproportionation character remarkably of the alloy and could improve magnetic properties of magnet powder. Increasing annealing temperature induces significant grain growth. And grain size produced by modified HDDR process is significantly smaller than those produced by conventional HDDR process.

Design and Test of the MEMS Coupled Piezoelectric- Electromagnetic Energy Harvester

Lian-min Cao,Zhi-xu Li,Cheng Guo,Peng-peng Li,Xiang-qiang Meng,Ting-ming Wang 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.4

This paper researches on the design and test of the output performance of double-end clamped MEMS coupled piezoelectric–electromagnetic energy harvester. It establishes the theoretical output model of the double-end clamped rectangular beam and trapezoidal beam piezoelectric–electromagnetic energy harvester, and optimizes the structure parameters of piezoelectric and electromagnetic unit with simulation analysis. It also respectively realizes the processing of piezoelectric and electromagnetic unit by MEMS and flexible PCB technology, and completes the performance test of structure prototype through the experimental system. The result showed that the capacity of MEMS coupled piezoelectric–electromagnetic energy harvester, which taked four coil piezoelectric with integrated electromagnetic in series, was 12.23 times higher than that of piezoelectric energy harvester. Also the output voltage and power of coupled trapezoidal beam energy harvester were respectively increased 18.89% and 2.26%, compared with coupled rectangular beam energy harvester.