Construction Process Analysis for a Single-Layer Folded Space Grid Structure in Considering Time-Dependent Effect

Zhen Zhou,Jing Wu,Shao-ping Meng,Qi Yu 한국강구조학회 2012 International Journal of Steel Structures Vol.12 No.2

A new long-span space grid structure system, “single-layer folded space grid” (SFSG), is applied in the Shenzhen Universiade Stadium. Compared with regular single-layer grid, the out-of plane stiffness and bearing capacity of the structure is improved with bending and uplifting of the structural units in SFSG, and the span capacity of the structure is then enhanced. Because of the large structural dimension, the construction process including assembling, closure and brace-unloading should be divided into many stages. As a result, there is very strong time-dependent effect for the structural stress state in construction. In this paper, based on matrix mechanics model of space grid structures, a time-dependent analysis method considering temperature variation during construction is presented based on matrix mechanics model to optimize the closure scheme. A combined brace element is presented to accurately simulate the mechanic character of temporary braces. In this way, the whole construction process of assembling, closure and brace-unloading are effectively and accurately analyzed for the SFSG structure of Shenzhen Universiade Stadium. The displacement state, stress distribution, and force changes in temporary braces are obtained to provide instruction for the design and control of construction process.

Semi-active control on long-span reticulated steel structures using MR dampers under multi-dimensional earthquake excitations

Zhen Zhou,Shao-ping Meng,Jing Wu,Yong Zhao 국제구조공학회 2012 Smart Structures and Systems, An International Jou Vol.10 No.6

This paper focuses on the vibration control of long-span reticulated steel structures under multidimensional earthquake excitation. The control system and strategy are constructed based on Magneto- Rheological (MR) dampers. The LQR and Hrovat controlling algorithm is adopted to determine optimal MR damping force, while the modified Bingham model (MBM) and inverse neural network (INN) is proposed to solve the real-time controlling current. Three typical long-span reticulated structural systems are detailedly analyzed, including the double-layer cylindrical reticulated shell, single-layer spherical reticulated shell, and cable suspended arch-truss structure. Results show that the proposed control strategy can reduce the displacement and acceleration effectively for three typical structural systems. The displacement control effect under the earthquake excitation with different PGA is similar, while for the cable suspended arch-truss, the acceleration control effect increase distinctly with the earthquake excitation intensity. Moreover, for the cable suspended arch-truss, the strand stress variation can also be effectively reduced by the MR dampers, which is very important for this kind of structure to ensure that the cable would not be destroyed or relaxed.

DBDTSO: Decentralized Bandwidth and Deployment Time Saving-oriented VM Image Management Mechanism for IaaS

Zhen Zhou,Shuyu Chen,Mingwei Lin,Guiping Wang 보안공학연구지원센터(IJGDC) 2013 International Journal of Grid and Distributed Comp Vol.6 No.3

Co-adsorption of electrolyte and protein to Ag colloid observed by surface-enhanced Raman scattering

Zhou, Zhen,Yang, In-sang,Huang, Genin Gary,Ozaki, Yukihiro Royal Society of Chemistry 2010 The Analyst Vol.135 No.9

<P>Protein detection using surface-enhanced Raman scattering (SERS) usually requires electrolytes to yield an enhanced SERS signal. However, the adsorption mechanism of electrolyte and protein to Ag colloid is not yet clearly understood. In this work, we have investigated co-adsorption of NO<SUB>3</SUB><SUP>−</SUP> and lysozyme to Ag colloid using SERS. Three experimental factors including concentration of lysozyme (10<SUP>−5</SUP> and 10<SUP>−6</SUP> M), concentration of NO<SUB>3</SUB><SUP>−</SUP> (0, 1, 2, 3 and 5 mM) and drying temperature (25 and 100 °C) have been studied. The results have shown that the co-adsorption of the adsorbates (lysozyme and NO<SUB>3</SUB><SUP>−</SUP>) on a SERS substrate and the non-absorption of NO<SUB>3</SUB><SUP>−</SUP> on the substrate can be controlled by using different experimental conditions. The co-adsorption manner of lysozyme and NO<SUB>3</SUB><SUP>−</SUP> is consistent with the mechanism of double-layer adsorbates when a protein adsorbs on a solid/liquid interface. The variation in protein conformation, especially the main-chain conformation, seems to affect the adsorption manner of the adsorbates. It has been found that the final adsorption result is not affected by the addition sequence of lysozyme and NO<SUB>3</SUB><SUP>−</SUP> during the sample preparation.</P> <P>Graphic Abstract</P><P>The co-adsorption of electrolyte and protein to Ag colloid observed by SERS would be helpful in understanding the adsorption mechanism of a protein on Ag colloids, and useful in designing protocol for preparing a SERS sample for protein detection. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0an00150c'> </P>

Minimizing Average Startup Latency of VMs by Clustering-based Template Caching Scheme in an IaaS System

Zhen Zhou,Shuyu Chen,Mingwei Lin,Guiping Wang,Qian Yang 보안공학연구지원센터(IJUNESST) 2013 International Journal of u- and e- Service, Scienc Vol.6 No.6

Minimizing Average Startup Latency of VMs by an Optimized VM Templates Caching Mechanism Based on K-Medoids Clustering in an IaaS System with Multi-cluster of Servers

Zhen Zhou,Shuyu Chen,Mingwei Lin,Guiping Wang,Qian Yang 보안공학연구지원센터 2015 International Journal of Grid and Distributed Comp Vol.8 No.3

Investigation of the behavior of a crack between two half-planes of functionally graded materials by using the Schmidt method

Zhou, Zhen-Gong,Wang, Biao,Wu, Lin-Zhi Techno-Press 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.19 No.4

In this paper, the behavior of a crack between two half-planes of functionally graded materials subjected to arbitrary tractions is resolved using a somewhat different approach, named the Schmidt method. To make the analysis tractable, it is assumed that the Poisson's ratios of the mediums are constants and the shear modulus vary exponentially with coordinate parallel to the crack. By use of the Fourier transform, the problem can be solved with the help of two pairs of dual integral equations in which the unknown variables are the jumps of the displacements across the crack surfaces. To solve the dual integral equations, the jumps of the displacements across the crack surfaces are expanded in a series of Jacobi polynomials. This process is quite different from those adopted in previous works. Numerical examples are provided to show the effect of the crack length and the parameters describing the functionally graded materials upon the stress intensity factor of the crack. It can be shown that the results of the present paper are the same as ones of the same problem that was solved by the singular integral equation method. As a special case, when the material properties are not continuous through the crack line, an approximate solution of the interface crack problem is also given under the assumption that the effect of the crack surface interference very near the crack tips is negligible. It is found that the stress singularities of the present interface crack solution are the same as ones of the ordinary crack in homogenous materials.

Comparative Study between ZOOMit and Conventional Intravoxel Incoherent Motion MRI for Assessing Parotid Gland Abnormalities in Patients with Early- or Mid-Stage Sjögren’s Syndrome

Zhou Qing-Qing,Zhang Wei,Yu Yu-Sheng,Li Hong-Yan,Wei Liang,Li Xue-Song,He Zhen-Zhen,Zhang Hong 대한영상의학회 2022 Korean Journal of Radiology Vol.23 No.4

Objective: To compare the reproducibility and performance of quantitative metrics between ZOOMit and conventional intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) in the diagnosis of early- and mid-stage Sjögren’s syndrome (SS). Materials and Methods: Twenty-two patients (mean age ± standard deviation, 52.0 ± 10.8 years; male:female, 2:20) with early- or mid-stage SS and 20 healthy controls (46.9 ± 14.6 years; male:female, 7:13) were prospectively enrolled in our study. ZOOMit IVIM and conventional IVIM MRI were performed simultaneously in all individuals using a 3T scanner. Quantitative IVIM parameters - including tissue diffusivity (D), pseudodiffusion coefficient (D*), and perfusion fraction (f) - inter- and intra-observer reproducibility in measuring these parameters, and their ability to distinguish patients with SS from healthy individuals were assessed and compared between ZOOMit IVIM and conventional IVIM methods, appropriately. MR gland nodular grade (MRG) was also examined. Results: Inter- and intra-observer reproducibility was better with ZOOMit imaging than with conventional IVIM imaging (ZOOMit vs. conventional, intraclass correlation coefficient of 0.897–0.941 vs. 0.667–0.782 for inter-observer reproducibility and 0.891–0.968 vs. 0.814–0.853 for intra-observer reproducibility). Significant differences in ZOOMit f, ZOOMit D*, conventional D*, and MRG between patients with SS and healthy individuals (all p < 0.05) were observed. ZOOMit D* outperformed conventional D* in diagnosing early- and mid-stage SS (area under receiver operating curve, 0.867 and 0.658, respectively; p = 0.002). The combination of ZOOMit D*, MRG, and ZOOMit f as a new diagnostic index for SS, increased diagnostic area under the curve to 0.961, which was higher than that of any single parameter (all p < 0.01). Conclusion: Considering its better reproducibility and performance, ZOOMit IVIM may be preferred over conventional IVIM MRI, and may subsequently improve the ability to diagnose early- and mid-stage SS.

A Novel Form Analysis Method Considering Pretension Process for Suspen-dome Structures

Zhen Zhou,Yu-long Feng,Shao-ping Meng,Jing Wu 대한토목학회 2014 KSCE JOURNAL OF CIVIL ENGINEERING Vol.18 No.5

Suspen-dome is a kind of new prestressed space grid structure which is formed by combing a single-layer reticulated shell andtensegrity system. For the existence of lower flexible cable-strut system, form analysis is crucial for the mechanical performance ofsuspen-domes. This paper develops a novel form analysis method considering the influence of pretension process for suspen-domestructures. Some definitions of form analysis for suspen-dome structures are first expounded. Then an iterative method is presentedfor form analysis, and a sequential analysis method is proposed for pretension process simulation. By combining these two methods,a form analysis method considering pretension process is constructed for suspen-dome structures. Two examples are employed toverify the proposed method. Numerical example results show that both the error of nodal coordinates and cable forces can stablyconverge to set tolerances. According to a scheduled pretension scheme, form analysis results can accurately achieve the expectedinitial state. Engineering example results show that without considering the influence of pretension process, the form analysis wouldbe error and the final state after all cables tensioned deviates greatly from the expected initial state. However, this can be achievedaccurately through the proposed method in this paper.

Pretension process control based on cable force observation values for prestressed space grid structures

Zhou, Zhen,Meng, Shao-Ping,Wu, Jing Techno-Press 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.34 No.6

Pointing to the design requirement of prestressed space grid structure being the target cable force, the pretension scheme decision analysis method is studied when there's great difference between structural actual state and the analytical model. Based on recursive formulation of cable forces, the simulative recursive system for pretension process is established from the systematic viewpoint, including four kinds of parameters, i.e., system initial value (structural initial state), system input value (tensioning control force scheme), system state parameters (influence matrix of cable forces), system output value (pretension accomplishment). The system controllability depends on the system state parameters. Based on cable force observation values, the influence matrix for system state parameters can be calculated, making the system controllable. Next, the pretension scheme decision method based on cable force observation values can be formed on the basis of iterative calculation for recursive system. In this way, the tensioning control force scheme that can meet the design requirement when next cyclic supplemental tension finished is obtained. Engineering example analysis results show that the proposed method in this paper can reduce a lot of cyclic tensioning work and meanwhile the design requirement can be met.