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Donkers S.,Grontmij Nederland BV the Netherlands | Ledoux H.,Technical University of Delft | Zhao J.,Tongji UniversityShanghai | Stoter J.,Technical University of Delft
Transactions in GIS | Year: 2015

Although the international standard CityGML has five levels of detail (LODs), the vast majority of available models are the coarse ones (up to LOD2, i.e. block-shaped buildings with roofs). LOD3 and LOD4 models, which contain architectural details such as balconies, windows and rooms, rarely exist because, unlike coarser LODs, their construction requires several datasets that must be acquired with different technologies, and often extensive manual work is needed. In this article we investigate an alternative to obtaining CityGML LOD3 models: the automatic conversion from already existing architectural models (stored in the IFC format). Existing conversion algorithms mostly focus on the semantic mappings and convert all the geometries, which yields CityGML models having poor usability in practice (spatial analysis, for instance, is not possible). We present a conversion algorithm that accurately applies the correct semantics from IFC models and that constructs valid CityGML LOD3 buildings by performing a series of geometric operations in 3D. We have implemented our algorithm and we demonstrate its effectiveness with several real-world datasets. We also propose specific improvements to both standards to foster their integration in the future. © 2015 John Wiley & Sons Ltd.

Zafari A.,University of MelbourneVictoria | Wei X.S.,University of MelbourneVictoria | Wei X.S.,Tongji UniversityShanghai | Xu W.,University of MelbourneVictoria | And 2 more authors.
Acta Materialia | Year: 2015

Abstract High pressure torsion was conducted to obtain nano-sized β grains in a metastable Ti-5553 alloy. Much finer grains of <50 nm were achieved, compared to >100 nm in a stable Ti-20 wt.% Mo alloy. The more effective grain refinement was attributed to stress induced martensitic transformation in the former, leading to the formation of thin α" plates which divide β grains into smaller domains. Further deformation resulted in a reverse α" to β transformation with decreasing α" sizes, generating a completely nano β grain structure at very large straining. A detailed description of the β grain refinement mechanism is provided. The reverse transformation is shown to be caused by the significantly increased free energy below a critical α" size of ∼10 nm, consistent with experimental observations. It is also calculated that extremely high energies were required for the formation of α" in nano-sized β grains, making further martensitic transformation impossible. It is concluded that the stress induced martensitic transformation and the subsequent reverse transformation are critical to producing nano-grained metastable β Ti alloys. © 2015 Acta Materialia Inc.

Xu J.,Tongji UniversityShanghai | Sun X.,Tongji UniversityShanghai
International Journal of Mechanical Sciences | Year: 2015

Abstract The potential beneficial performance of a Multi-Direction Quasi-Zero-Stiffness vibration isolator (MDQZS-VI) with linear time-delayed active control is investigated in this study. From the analysis of vibration property such as natural frequency, it is found that the isolation effectiveness of the MDQZS-VI for different directions can be adjusted respectively. The vertical direction natural frequency and damping property of the MDQZS-VI are dependent on structural parameters while the horizontal direction natural frequency and damping coefficient are related to the active control parameters. Moreover, bifurcation analysis shows that the values of control strength and time-delay have effect on the stability of horizontal vibration. By solving the displacement transmissibility for multi-direction, it is shown that structural parameters and active control coefficients could be designed deliberately so that natural frequencies are reduced and nonlinear damping coefficients are increased which is helpful for vibration suppression. The results provide a useful insight into the analysis and design of multi-direction QZS vibration isolator by exploiting potential nonlinear benefits of the time delay in vibration active control. © 2015 Elsevier Ltd.

Sun D.,Tongji UniversityShanghai | Lin T.,Tongji UniversityShanghai | Zhu X.,Tongji UniversityShanghai | Cao L.,Tongji UniversityShanghai
Construction and Building Materials | Year: 2015

Abstract Self-healing, as a very valuable characteristic, should be considered when selecting and designing constitutions of asphalt materials. It is necessary to develop a fundamental and universal healing evaluation indication based on the healing mechanism. However, most existing healing evaluation indication lacks physical meaning and hardly can predict the time-dependent healing process under different conditions. In this paper, the formulation of activation energy as a self-healing indication is developed based on the Arrhenius law. The procedure to get the activation energy of different asphalt mastic is put forward. Nine samples of different asphalt mastic are prepared. Then, the fatigue-rest-fatigue tests are employed to get the activation energy of nine asphalt mastic. Finally, the potential of the activation energy as the healing evaluation index for asphalt mastic is studied, and the effect of type of asphalt and filler, asphalt-filler ratio, damage degree on the value of activation energy is discussed. It is found that the healing activation energy can obviously distinguish the healing ability of different asphalt mastic. Healing activation energy represents the minimum energy required for the time-dependent strength gain and reflects the time-dependent strength gain rate, also can rank the time-dependent healing capacity of different asphalt mastic. © 2015 Elsevier Ltd.

Zhao X.,Tongji UniversityShanghai | Wang H.,Tongji UniversityShanghai | Hu X.,Tongji UniversityShanghai | Liu J.,Tongji UniversityShanghai | Jiang G.,Tongji UniversityShanghai
International Journal of Clinical and Experimental Medicine | Year: 2014

We present the first report of a rare case of typical carcinoid tumor of the lung in a patient with complete situs inversus. The patient was a 65-year-old woman with the chief complaint of productive and mild chest pain. Chest X-ray and computed tomography (CT) scans of the thorax showed a mirror image of the organs and vessels and revealed a tumor 2.5 cm in diameter in the left middle lobe. The patient underwent resection of the left middle lobe through posterolateral incision. Postoperative pathological examination returned a diagnosis of typical carcinoid tumor. The patient made an uneventful recovery. This case highlights the importance of considering malignant tumors in pulmonary nodules in patients with complete situs inversus. © 2014, International Journal of Clinical and Experimental Medicine. All rights reserved.

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