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Although building information modeling (BIM) has demonstrated to be an effective tool for the construction of urban rail transit worldwide, it has not gained the same popularity in the facility management (FM) of urban rail transit. The objective of this study is to investigate the BIM application areas for FM in urban rail transit from an innovation diffusion theory perspective, in order to gain efficient operation and maintenance (O&M) in urban rail transit. A total of 18 BIM application areas were first identified through semistructured interviews. A questionnaire survey was then conducted to further quantitatively characterize the relative advantage, ease of use, trialability, observability, and compatibility of these areas. Statistical analysis of the survey results provided evidence that, currently, BIM application areas directly related with facilities and equipment are most likely to be adopted. Correlation analysis further indicates that the perceived innovation diffusion characteristics of these BIM application areas significantly correlate with the development level of urban rail transit in different regions. The findings contribute to a broadened understanding of the complex innovation diffusion process of BIM for FM in urban rail transit and provide insights into how BIM can be more effectively adopted in the domain. [ABSTRACT FROM AUTHOR]

Although building information modeling (BIM) has demonstrated to be an effective tool for the construction of urban rail transit worldwide, it has not gained the same popularity in the facility management (FM) of urban rail transit. The objective of this study is to investigate the BIM application areas for FM in urban rail transit from an innovation diffusion theory perspective, in order to gain efficient operation and maintenance (O&M) in urban rail transit. A total of 18 BIM application areas were first identified through semistructured interviews. A questionnaire survey was then conducted to further quantitatively characterize the relative advantage, ease of use, trialability, observability, and compatibility of these areas. Statistical analysis of the survey results provided evidence that, currently, BIM application areas directly related with facilities and equipment are most likely to be adopted. Correlation analysis further indicates that the perceived innovation diffusion characteristics of these BIM application areas significantly correlate with the development level of urban rail transit in different regions. The findings contribute to a broadened understanding of the complex innovation diffusion process of BIM for FM in urban rail transit and provide insights into how BIM can be more effectively adopted in the domain. [ABSTRACT FROM AUTHOR]

The rock mechanical properties under the effect of high temperature present a great significance on underground rock engineering. In this paper, the mechanical properties of sandstones, marbles, and granites under real-time heating were investigated with a servo-controlled compression apparatus. The results show that mechanical behaviours of all the three types of rocks are influenced by real-time heating to different degrees. Due to thermal cracking, the uniaxial compressive strengths decrease as the heating temperature rises from room temperature to 400°C. Above 400°C, the sandstone exhibits a significant increase in UCS because of the sintering reaction. The sintering enlarges the contact area and friction between crystal grains in the sandstone, which strengthens the bearing capacity. For marbles, the UCS continues to decrease from 400°C to 600°C due to thermal cracking. However, the carbonate in the marble begins to decompose after 600°C. The generated particles would fill the cracks in the marble and increase the strength. For granites, their UCS presents a sharp decline after 400°C because of thermal cracking. For all rock elastic modulus, they present a decreasing trend, and this indicates that the rock's ability to resist deformation gradually weakens under the effect of temperature. In general, rock mechanical behaviours under real-time heating differ from those in normal situations, and use of the parameters presented here is important for underground rock engineering related to high temperature and can improve the precision in theoretical and numerical analysis. [ABSTRACT FROM AUTHOR]

Face gear dynamics is addressed by many scholars. However, dynamic behaviors of face gear drives associated with pinion dedendum fatigue cracks are yet to be investigated. Thus, in the study, a calculation solution of static transmission errors (STE) of face gear drives associated with pinion dedendum fatigue cracks is constructed, based on the proposed equivalent face gear drives, and a four-degree-of-freedom (DOF) dynamic model of face gear drives is formulated. The dynamic behaviors of an example case of face gear drives associated with pinion dedendum fatigue cracks are investigated. The simulation results indicate natural frequencies of face gear drives would be decreased with pinion dedendum fatigue crack extensions; the relationship between accelerations and velocities of face gear drives, dynamic mesh forces, and vibration accelerations at bearings would also be changed. However, pinion dedendum fatigue cracks of face gear drives are detected difficultly, due to simulation result similarities. Therefore, a determination solution for pinion dedendum fatigue cracks of face gear drives is proposed. The result shows a trend of vibration accelerations at bearings, namely, a first decreasing and then increasing tendency, which could be beneficial to detecting pinion dedendum fatigue cracks of face gear drives. These contributions would improve engineering applications of face gear drives in the future. [ABSTRACT FROM AUTHOR]

Asymmetric group key agreement is a cryptographic primitive allowing a group of users to negotiate a common public encryption key while each of them holds a different secret private decryption key. Anyone (including outsiders) with the public encryption key can send encrypted messages to the group members, and then the group members can decrypt the messages. Authenticated key agreement protocols authenticate the identities of users to ensure that only the intended group members can establish a session in which the group members can communicate with each other. Dynamic asymmetric group key agreement concerns about the scenarios such as ad hoc networks in which the group members may join or leave at any given time. In this paper, we propose a one-round authenticated dynamic protocol for symmetric group key agreement. For efficiency reasons, we employ the identity-based public-key cryptography (IB-PKC) to authenticate users rather than the public key infrastructure and the certificate-less public-key cryptography. Our analysis shows that the proposals in the paper can resist active attacks and meet many desirable security attributes. Besides, our protocol allows users to join or leave the group at the same time. Furthermore, our protocol is round-optimal and has a quite good performance as compared with previous works. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In order to further explore the coordination gain from the cloud cellular network, the Coordinated Semidirectional Distributed Antenna System (CS-DAS) is proposed with deploying 180-degree sector antennas. Based on the CS-DAS, the coordinated cellular deployment structure is established with corresponding communication procedure designs. The handover process for CS-DAS is designed with less handover rate and signaling overheads. The system performances of ergodic capacity and Energy Efficiency are derived, with a strong focus on the downlink performances, and analyzed with comparisons of current cellular structure. The numerical expressions of ergodic capacity are obtained with improvements of coordinated gain. The Energy Efficiency with different transmission modes is also investigated. The simulation results verify the performance improvements. [ABSTRACT FROM AUTHOR]

Spectral efficient transmission techniques are necessary and promising for future broadband wireless communications, where the quality of service (QoS) and/or max-min fair (MMF) of intended users are often considered simultaneously. In this paper, both the QoS problem and the MMF problem are investigated together for transmit beamforming in broadband multigroup multicast channels with frequency-selective fading characters. We first present a basic algorithm by directly using the results in frequency-flat multigroup multicast systems (Karipidis et al., 2008), namely, the approximation algorithms in this paper, for both problems, respectively. Due to high computational consumption nature of the approximation algorithms, two reduced-complexity algorithms for each of the two problems are proposed separately by introducing the time-frequency correlations. In addition, parameters in the new time-frequency formulations, such as the number of optimization matrix variables and the taps of the beamformer with finite impulse response (FIR) structure, can be used to make a reasonable tradeoff between computational burden and system performance. Insights into the relationship between the two problems and some analytical results of the computational complexity of the proposed algorithms are also studied carefully. Numerical simulations indicate the efficiency of the proposed algorithms. [ABSTRACT FROM AUTHOR]

Euphorbia helioscopia L. is a traditional Chinese medicine; recently research found that its ethyl acetate extract (EAE) plays an important role on tumor cell proliferation, apoptosis, invasion, and metastasis in vitro. But the effect of EAE for tumor cells in vivo has not been reported. To explore the inhibitory effect of EAE and molecular mechanism on hepatocellular carcinoma (HCC) SMMC-7721 cells in vivo, we utilized the nude mouse xenograft model of HCC. Treated with EAE (50, 100, and 200 μg/mL), the volume of xenograft was measured during the entire process of EAE treatment. In EAE treatment group, the volume of xenograft was significantly reduced compared with the control group (P<0.05) and the protein expressions of CyclinD1, bcl-2, and MMP-9 were reduced, while those of bax, caspase-3, and nm23-H1 were increased. A significant change trend with increasing EAE concentrations has presented, compared with controls. Moreover, the ultrastructural morphology of xenografts showed significant changes, including nuclear pyknosis and chromatin condensation, We found that EAE could effectively inhibit tumor growth, induce apoptosis, and inhibit tumor invasion and metastasis in vivo; it is suggested that EAE is a potential candidate for as a new anticancer agent. [ABSTRACT FROM AUTHOR]

The concept of Cooperated Multipoint (CoMP) transmission is proposed for LTE-Advanced, which is in a form of distributed networks. In this background, a novel CoMP architecture is proposed in this paper, based on Group Cell concept in China FuTURE 4G TDD systems. Moreover, four actual scenarios are also concluded in CoMP, which, respectively, are single user in intracell, multiple users in intracell, single user in intercell and slide handover in intercell. In addition, a joint subcarrier optimization method is proposed to mitigate the intercell interference and improve performance under CoMP architecture; the method includes two aspects, which, respectively, are subcarrier allocation with maximum gain to interference plus noise ratio (GINR) and power allocation based on balanced signal to interference plus noise ratio (SINR). On this basis, three combined schemes are presented in simulation. Compared with traditional scheme, the proposed scheme improves throughputs and reduces blocking probability. Moreover, the average data rates in cell edge are also raised. [ABSTRACT FROM AUTHOR]