2025-04-22 2016, Volume 22 Issue 1

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  • Mingming Zhang , Hsien-Shun Wu , Guangfu Li , Xin Wang , Ching-Kuang C. Tzuang

    A 130 nm CMOS complementary-conducting-strip transmission line(CCS-TL)based multi-stage amplifier beyond 100 GHz was presented in this paper. Different structural parameters were investigated to achieve higher quality factor for the matching circuits. Moreover, CCS-TL based Marchand balun was implemented to achieve higher output power. The measured small signal gain was higher than 5 dB from 101 GHz to 110 GHz. DC power consumption was 67.2 mW with VD=1.2 V, and the chip size including contact PADs was 1.12 mm×0.81 mm.

  • Xiaonan Zhao , Chunping Hou , Qing Wang , Hua Chen , Liangzhou Pu

    To establish wireless channel suitable for the cabin environment, the power coverage was investigated with distributed antenna system and centralized antenna system based on the actual measurement of channel impulse response. The results indicated that the distributed antenna system has more uniform power coverage than the centralized antenna system. The average relative errors of receiving power of both antennas were calculated. The optimal position of the centralized antenna was obtained by Gaussian function refinement, making the system achieve a better transmission power with the same coverage effect, and providing a reference for antenna location in the future real communication in the cabin.

  • Weijie Lü , Donglin Bai

    In this paper, a sensing model for the coverage analysis of wireless sensor networks is provided. Using this model and Monte Carlo method, the ratio of private range to sensing range required to obtain the desired coverage can be derived considering the scale of deployment area and the number of sensor nodes. Base on the coverage analysis, an energy-efficient distributed node scheduling scheme is proposed to prolong the network lifetime while maintaining the desired sensing coverage, which does not need the geographic or neighbor information of nodes. The proposed scheme can also handle uneven distribution, and it is robust against node failures. Theoretical and simulation results demonstrate its efficiency and usefulness.

  • Chao Wang , Jinzhao Wu , Hongyan Tan , Jun Fu

    Using Baire metric, this paper proposes a generalized framework of transition system approximation by developing the notions of approximate reachability and approximate bisimulation equivalences. The proposed framework captures the traditional exact equivalence as a special case. Approximate reachability equivalence is coarser than approximate bisimulation equivalence, just like the hierarchy of the exact ones. Both approximate equivalences satisfy the transitive property, consequently, they can be used in transition system approximation.

  • Qiegen Liu , Hongyang Lu , Minghui Zhang

    In this paper, a two-level Bregman method is presented with graph regularized sparse coding for highly undersampled magnetic resonance image reconstruction. The graph regularized sparse coding is incorporated with the two-level Bregman iterative procedure which enforces the sampled data constraints in the outer level and updates dictionary and sparse representation in the inner level. Graph regularized sparse coding and simple dictionary updating applied in the inner minimization make the proposed algorithm converge with a relatively small number of iterations. Experimental results demonstrate that the proposed algorithm can consistently reconstruct both simulated MR images and real MR data efficiently, and outperforms the current state-of-the-art approaches in terms of visual comparisons and quantitative measures.

  • Denghua Zhong , Nengming Hu , Zhengfei Cheng , Peng Lü , Dawei Tong

    In most studies of tunnel boring machine(TBM)tunnelling, the groundwater pressure was not considered, or was simplified and exerted on the boundary of lining structure. Meanwhile, the leakage, which mainly occurs in the segment joints, was often ignored in the relevant studies of TBM tunnelling. Additionally, the geological models in these studies were simplified to different extents, and mostly were simplified as homogenous bodies. Considering the deficiencies above, a 3D refined model of the surrounding rock of a tunnel is firstly established using NURBS-TIN-BReP hybrid data structure in this paper. Then the seepage field of the surrounding rock considering the leakage in the segment joints is simulated. Finally, the stability of TBM water diversion tunnel is studied coupled with the seepage simulation, to analyze the stress-strain conditions, the axial force and the bending moment of tunnel segment considering the leakage in the segment joints. The results illustrate that the maximum radial displacement, the minimum principal stress, the maximum principal stress and the axial force of segment lining considering the seepage effect are all larger than those disregarding the seepage effect.

  • Hongyan Ding , Yaohua Guo , Yuguo Liang , Puyang Zhang

    The seismic behaviors of an integral concreting frame, a light steel storey-adding frame and a storey-adding frame strengthened with carbon fiber reinforced polymer(CFRP)were investigated under low-cycle and repeated load(scale 1:3). The failure characteristics, hysteretic behavior, rigidity degeneracy, deflection ductility and energy-dissipation capacity of the three specimens were compared. The test results reveal that chemically-bonded rebar technique can meet the requirements of storey-adding engineering. The carrying capacity, the deflection ductility, the energy-dissipating capacity and seismic performance of the light steel storey-adding frame are higher than those of the integral concreting frame, and they are the highest in the storey-adding frame strengthened with CFRP.

  • Bo Cui , Zhengyin Zhou , Xiaoling Wang , Ruirui Sun , Xiaopei Sun

    It is imperative to develop a risk assessment system for quickly predicting storm surge disaster due to the vulnerability of Tianjin Binhai New Area. The flood routing model with user-defined breaches was firstly established based on the seed spread algorithm in order to achieve a rapid forecasting of storm surge flood information. Furthermore, fuzzy mathematics was utilized to identify the storm disaster grade, and the hazard mapping was conducted to visually obtain the hazard spatial and temporal distribution. Finally, the flood routing visualization method was proposed based on numerical simulation of storm surge to achieve the reappearance scene of dynamic evolution process. The developed system can play a vital role in the management and decision-making of sea dyke mitigation engineering in Tianjin Binhai New Area.

  • Jiawen Li , Yougang Tang , Bin Wang

    A novel floating foundation to support the NREL offshore 5 MW wind turbine was designed conceptually by combining the characteristics of barge and Spar. The main focus was structural design and hydrodynamic modelling. Based on this novel floating foundation, the hydrodynamic performance was investigated in the frequency domain and time domain by using the wave analysis software HydroD and DeepC from Det Norske Veritas. The frequency domain analysis was conducted to investigate the effects of the incident wave angle and water depth. The time-domain analysis was carried out to evaluate the response of the floating foundation under a selected operational condition. The hydrodynamic performances of this floating foundation with respect to time series and response spectra were also investigated in this study.

  • Zhongwei Zhao , Zhihua Chen , Hongbo Liu

    The healing temperature of suspen-dome with stacked arches(SDSA)and arch-supported single-layer lattice shell structures was investigated based on the genetic algorithm. The temperature field of arch under solar radiation was derived by FLUENT to investigate the influence of solar radiation on the determination of the healing temperature. Moreover, a multi-scale model was established to apply the complex temperature field under solar radiation. The change in the mechanical response of these two kinds of structures with the healing temperature was discussed. It can be concluded that solar radiation has great influence on the healing temperature, and the genetic algorithm can be effectively used in the optimization of the healing temperature for hybrid structures.

  • Zhongxian Chen , Haitao Yu , Chunyuan Liu , Liwei Hong

    In this paper, the design, construction and ocean testing of a wave energy conversion system are studied. Based on the motion characteristics of double buoys in ocean waves, a wave energy conversion system with permanent magnet tubular linear generator (PMTLG) is proposed to convert ocean wave energy into electricity. The wave energy conversion system was installed in the Yellow Sea near Lianyungang, China. The ocean test results indicate that it had dynamic and static performance, and obtained an expected amount of electricity. The calculation result indicates the average output power was about 1,000,W, and the conversion efficiency from wave energy into electricity was 1.4%,. In addition, the wireless data communication, mechanics and oceanography were also discussed.

  • Jinsheng Sun , Leilei Dai , Tingting Ma , Changning Guo , Hongyuan Wei , Zhenghu Li

    A novel heat-integrated distillation scheme on pilot scale for producing C5 foaming agent, a mixture of isopentane and pentane in a certain proportion, was proposed with the aid of process simulation. Compared with the conventional distillation scheme, C5 foaming agent was directly separated at the top of the original isopentane or pentane column in the novel scheme, instead of first refining the two isomerides to high purities and then mixing them into final products. This improvement reduced the difficulty of the separation and avoided meaningless exergy loss caused by re-mixing, which finally contributed to an energy-efficient design by a big margin. Moreover, the column grand composite curves(CGCCs)were used to modify all distillation columns, indicating that there is potential to improve the energy efficiency further. Therefore, double-effect, or heat-integrated distillation was also adopted. Energy and exergy analyses were then conducted to evaluate the effectiveness of the proposed scheme for the purpose of energy saving. The simulation results of the conventional distillation scheme were in agreement with its on-site counterpart. Analyses showed that the novel heat-integrated scheme reduced hot utility by 27.12%,, cold utility by 24.49%,, and total exergy loss by 23.95%,.

  • Wuke Lang , Weijiang Zhang , Yin Tang , Jiao Xu , Lei Zhang

    A method was proposed to determine boron trifluoride in boron trifluoride complex using fluoride ion selective electrode(ISE). Hydroxide was chosen to mask aluminum for the determination of 0.01—0.1 mol/L of fluoride. The simulation indicated that the permissible aluminum masked at a certain pH value was limited and hardly related to F-concentration and boric acid. It is better to control pH value below 11.5 and the aluminum concentration within 0.025 mol/L to minimize the interference of hydroxide to the fluoride ISE. The decomposition conditions of boron trifluoride by aluminum chloride were investigated. It is found that the F-detection ratio will approach 1.0 if the Al/F molar ratio is 0.3—0.7 and aluminum concentration is no more than 0.02 mol/L when heated at 80 °C for 10 min. In one word, hydroxide is quite fit to mask aluminum for samples which contain high content of fluoride and aluminum and the BF3 content can be successfully determined by this method.

  • Xiaohong Liu , Jie Fan , Wenjuan Li

    Based on concave function, the problem of finding the sparse solution of absolute value equations is relaxed to a concave programming, and its corresponding algorithm is proposed, whose main part is solving a series of linear programming. It is proved that a sparse solution can be found under the assumption that the connected matrixes have range space property(RSP). Numerical experiments are also conducted to verify the efficiency of the proposed algorithm.