Simulation of Optimized Evacuation Processes based on Sub-Goal CA Model

Zhiwen Hu,Huaqing Mao,Li Zhu 보안공학연구지원센터 2016 International Journal of Grid and Distributed Comp Vol.9 No.5

With the full swing of computer technology, evacuation models are constructed and simulated via computers to study the various phenomena and behaviors during the evacuation process. They open unique potential opportunity to evaluate the architectural design and provide the decision support for the emergency evacuation plans. This paper details a capacity constrained route planner (CCRP) algorithm, which is used to optimize evacuation path, and the distance map based on sub-goal cellular automata (CA) is also proposed to simulate the evacuation scenarios. Two evacuation scenarios are further discussed, and the experimental results strongly suggested that the sub-goal CA model could simulate the evacuation scenarios and evaluate the emergency evacuation plans effectively and finally help us penetrate to the essence of reality.

Identification of flutter derivatives of bridge decks using CFD-based discrete-time aerodynamic models

Zhiwen Zhu,Ming Gu 한국풍공학회 2014 한국풍공학회지 Vol.18 No.3

This paper presents a method to extract flutter derivatives of bridge decks based on acombination of the computational fluid dynamics (CFD), system simulations and system identifications. Theincompressible solver adopts an Arbitrary Lagrangian-Eulerian (ALE) formulation with the finite volumediscretization in space. The imposed sectional motion in heaving or pitching relies on exponential time seriesas input, with aerodynamic forces time histories acting on the section evaluated as output. Systemidentifications are carried out to fit coefficients of the inputs and outputs of ARMA models, as to establishdiscrete-time aerodynamic models. System simulations of the established models are then performed as toobtain the lift and moment exerting on the sections to a sinusoidal displacement. It follows that flutterderivatives are identified. The present approaches are applied to a hexagon thin plate and a real bridge deck. The results are compared to the Theodorsen closed-form solution and those from wind tunnel tests. Satisfactory agreements are observed.

Continuous Pad Dyeing of Cotton Fabric in a Non-Aqueous Medium for Realizing Ultra-High Fixation and Washing-Free

Zhiwen Wang,Liujun Pei,Hongjuan Zhang,Hao Li,Jiping Wang 한국섬유공학회 2022 Fibers and polymers Vol.23 No.5

In traditional water-based dyeing system, a low fixation of reactive dye requires six to ten times washing afterdyeing, which consumes a lot of water and results in huge dyeing effluent. To alleviate this issue, the development of asustainable dyeing technology of cotton textile is essential. In the present investigation, silicone non-aqueous medium wasemployed to improve the fixation of dye with a pad-dyeing process under the optimized dyeing parameters. The appropriatewashing-free dyeing conditions were recommended as follows: the padded fabric was placed at 105 oC for 15-30 s tocomplete pre-drying to decrease the water content rapidly, and then fixed in non-aqueous medium for 80-90 s at 95 oC. Afterdyeing, the dyed fabric was treated with 30 g/l fixing agent through pre-dried at 80 oC and baked at 160 oC. The resultsindicated that the final fixation of dye was above 95 %, and the dry rubbing fastness of dyed cotton fabric can reach grade 5. Moreover, the wet rubbing fastness and washing fastness of dyed cotton fabric can reach grade 3-4 and 4, respectively. Therefore, it can obtain the washing-free dyeing of cotton fabric with reactive dye. If the washing procedure was omitted inthe industrial application, the environmental cost of cotton dyeing would be greatly decreased. This method provides asubstantial reduction in wastewater effluent, which will be considerably potential for industrial application.

Performance evaluation of inerter-based damping devices for structural vibration control of stay cables

Zhiwen Huang,Xugang Hua,Zhengqing Chen,Huawei Niu 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.23 No.6

Inerter-based damping devices (IBBDs), which consist of inerter, spring and viscous damper, have been extensively investigated in vehicle suspension systems and demonstrated to be more effective than the traditional control devices with spring and viscous damper only. In the present study, the control performance on cable vibration reduction was studied for four different inerter-based damping devices, namely the parallel-connected viscous mass damper (PVMD), series-connected viscous mass damper (SVMD), tuned inerter dampers (TID) and tuned viscous mass damper (TVMD). Firstly the mechanism of the ball screw inerter is introduced. Then the state-space formulation of the cable-TID system is derived as an example for the cable-IBBDs system. Based on the complex modal analysis, single-mode cable vibration control analysis is conducted for PVMD, SVMD, TID and TVMD, and their optimal parameters and the maximum attainable damping ratios of the cable/damper system are obtained for several specified damper locations and modes in combination by the Nelder-Mead simplex algorithm. Lastly, optimal design of PVMD is developed for multi-mode vibration control of cable, and the results of damping ratio analysis are validated through the forced vibration analysis in a case study by numerical simulation. The results show that all the four inerter-based damping devices significantly outperform the viscous damper for single-mode vibration control. In the case of multi-mode vibration control, PVMD can provide more damping to the first four modes of cable than the viscous damper does, and their maximum control forces under resonant frequency of harmonic forced vibration are nearly the same. The results of this study clearly demonstrate the effectiveness and advantages of PVMD in cable vibration control.

Impact of axial power distribution on thermal-hydraulic characteristics for thermionic reactor

Zhiwen Dai,Chenglong Wang,Dalin Zhang,Wenxi Tian,Suizheng Qiu,G.H. Su 한국원자력학회 2021 Nuclear Engineering and Technology Vol.53 No.12

Reactor fuel's power distribution plays a vital role in designing the new generation thermionic SpaceReactor Power Systems (SRPS). In this paper, the 1/12th SPACE-R's full reactor core was numericallyanalyzed with two kinds of different axial power distribution, to identify their impacts on thermalhydraulic and thermoelectric characteristics. In the benchmark study, the maximum error betweennumerical results and existing data or design values ranged from 0.2 to 2.2%. Four main conclusions wereobtained in the numerical analysis: a) The axial power distribution has less impact on coolant temperature. b) Axial power distribution influenced the emitter temperature distribution a lot, when the corepower was cosine distributed, the maximum temperature of the emitter was 194 K higher than that ofthe uniform power distribution. c) Comparing to the cosine axial power distribution, the uniform axialpower distribution would make the maximum temperature in each component of the reactor core muchlower, reducing the requirements for core fuel material. d) Voltage and current distribution were similarto the axial electrode temperature distribution, and the axial power distribution has little effect on theoutput power

How Did Reviewers Give Their Reviews? Characterizing Review Activity in Academic Conferences

Zhiwen Yu,Xinxin Zhang,Yunji Liang,Daqing Zhang 보안공학연구지원센터 2013 International Journal of Multimedia and Ubiquitous Vol.8 No.5

Effect of Ultrasonic Power on Grain Refinement and Purification Processing of AZ80 Alloy by Ultrasonic Treatment

Zhiwen Shao,Qichi Le,Zhiqiang Zhang,Jianzhong Cui 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.2

Ultrasound with different powers was applied to treat AZ80 alloy melt to attain grain refinement or purifi-cation processing of the alloy. The influence of ultrasonic powers from 0 W to 1400 W on microstruc-tures of the AZ80 alloy with ultrasonic grain refinement treatment was investigated. The average grain size of the alloy could be decreased from 387 µm to 147 µm after the ultrasound with the optimal power 600 W was applied to treat the melt. The effect of ultrasonic powers from 0 W to 230 W on the inclusion distribution in the ingot that was treated by ultrasonic purification processing was also studied. The opti-mal ultrasonic power in the ultrasonic purification processing was 80 W. In order to gain insight into the mechanism by which ultrasonic power affected the microstructure of the alloy or inclusion distribution in the ingot, numerical simulations were carried out and the ultrasonic field propagation in the melt was characterized.

Ensemble convolutional neural networks for automatic fusion recognition of multi‐platform radar emitters

Zhiwen Zhou,Gaoming Huang,Xuebao Wang 한국전자통신연구원 2019 ETRI Journal Vol.41 No.6

Presently, the extraction of hand‐crafted features is still the dominant method in radar emitter recognition. To solve the complicated problems of selection and updation of empirical features, we present a novel automatic feature extraction structure based on deep learning. In particular, a convolutional neural network (CNN) is adopted to extract high‐level abstract representations from the time‐frequency images of emitter signals. Thus, the redundant process of designing discriminative features can be avoided. Furthermore, to address the performance degradation of a single platform, we propose the construction of an ensemble learning‐based architecture for multi‐platform fusion recognition. Experimental results indicate that the proposed algorithms are feasible and effective, and they outperform other typical feature extraction and fusion recognition methods in terms of accuracy. Moreover, the proposed structure could be extended to other prevalent ensemble learning alternatives.

Multiple principal-agent relationships, corporate-control mechanisms and expropriation through related party transactions

Zhiwen Zhu 인하대학교 정석물류통상연구원 2009 인하대학교 정석물류통상연구원 학술대회 Vol.2009 No.10

This study investigated the intermediation of expropriation in the linkage between corporate governance and firm value. We manifested the triple principal-agent relationships among minority shareholders, majority shareholders and the board of directors, and conceptualized the expropriation as rents demanded by majority shareholders to compensate their agency function in a theoretical framework of internal and external corporate-control mechanisms for firms with concentrated ownership structure. By using related party transactions as a direct measure for expropriation and the event study, we corroborated the negative value effect of expropriation in China"s stock markets, and found that the controlling capability of controlling shareholders, ownership balancing, identity of controlling shareholders, stock incentives for the board/executives, and the proportion of tradable shares are significantly associated with expropriation. We also found an interact effect between the proportion of tradable shares ande the controlling shareholders on expropriation.

Vision measurement of gear pitting based on DCGAN and U-Net

Zhiwen Wang,Yi Qin,Weiwei Chen 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.7

To quantitatively detect the gear pitting, this paper proposes a vision measurement method based on deep convolutional generative adversarial network (DCGAN) and fully convolutional segmentation network (U-Net) for measuring the area ratio of gear pitting. A machine vision system is designed to automatically collect the pitting images of all gear teeth obtained from gear fatigue tests, but the pitting images are not sufficient due to the high cost of gear fatigue test. To solve the problem of small sample, DCGAN is applied to expand pitting samples. By the expansive sample set, the edge detection algorithm and U-Net are respectively used to segment the tooth surface and pitting. The proposed approach is applied to measure the gear pitting, and a comprehensive evaluation index is designed to evaluate the performance of gear pitting detection. Experimental results show that the average relative error and the absolute error of pitting area ratio obtained by the proposed method are respectively 7.83 % and 0.18 %, which are much lower than those obtained by the conventional detection method without sample augmentation. Thus, the proposed method has satisfactory accuracy and precede the detection method without sample augmentation.