Knowledge Discovery from the Data of Long Distance Travel Mode Choices Based on Rough Set Theory

Weijie Wang,Moon Namgung 보안공학연구지원센터 2007 International Journal of Multimedia and Ubiquitous Vol.2 No.2

The purpose of this study is to find the relationships between personal demographic attributes and long distance travel mode choices based on the Artificial Intelligence technique-rough set theory. Rough set theory can learn and refine decision rules or hidden facts from the incomplete observed data without the constraints of statistical assumptions. Also the induced decision rules are expressed in natural language, which can help policymakers in the decision making process. In the study, we conducted a survey to collect the peoples’ most preferred travel mode choices for the given destination and people’s demographic information. We analyzed the observed data based the rough set theory, calculated and discussed the approximation, core, reduct and rules of the data. The results of validation test were very promising, which showed that the induced decision rules could represent the relationships between data with the accuracy of 74.59%.

Determination of the Bearing Capacity of a Concrete-filled Steel Tubular Arch Support for Tunnel Engineering: Experimental and Theoretical Studies

Weijie Zhang,Weiteng Li,Ning Yang,Qi Wang,Tingchun Li,Gang Wang 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.7

Although Concrete-filled Steel Tubular (CFST) arch support technology for transportation tunnels and mining roadways is developing rapidly, research regarding the determination of the bearing capacity of the CFST arch support is still limited. Based on a literature analysis, the definition and expression form of the bearing capacity of CFST supporting arch Qu was clarified, and determination approaches via laboratory testing and theoretical calculation methods were recommended. Full-size mechanical tests of CFST arches were performed by adhering to the suggested loading pattern that uses a number of hydraulic cylinders along the arch profile to simulate the surrounding rock pressure. The failure mode of the arches was determined as elastic-plastic instability with an extreme point. The critical criterion of global instability for the tested arch was proposed as the critical CFST section reaching the compression-bending limit. Based on the above criterion, a specific process for determining the Qu by theoretical calculation was proposed. Calculation examples show that the calculation results deviations were less than 4% compared with the tests results, and the reliability and accuracy of the new theoretical approach were thus verified. Finally, the limitations of the calculation method were noted.

A Logic-compatible Embedded DRAM Utilizing Common-body Toggled Capacitive Cross-talk

Weijie Cheng,Hritom Das,Yeonbae Chung 대한전자공학회 2016 Journal of semiconductor technology and science Vol.16 No.6

This paper presents a new approach to enhance the data retention of logic-compatible embedded DRAMs. The memory bit-cell in this work consists of two logic transistors implemented in generic triple-well CMOS process. The key idea is to use the parasitic junction capacitance built between the common cell-body and the data storage node. For each write access, a voltage transition on the cell-body couples up the data storage levels. This technique enhances the data retention and the read performance without using additional cell devices. The technique also provides much strong immunity from the write disturbance in the nature. Measurement results from a 64-kbit eDRAM test chip implemented in a 130 nm logic CMOS technology demonstrate the effectiveness of the proposed circuit technique. The refresh period for 99.9% bit yield measures 600 μs at 1.1 V and 85℃, enhancing by 87.5% over the conventional design approach.

A comprehensive quality analysis of randomized controlled clinical trials of Asian ginseng and American ginseng based on the CONSORT guideline

Weijie Chen,Xiuzhu Li,Zhejie Chen,Wei Hao,Peifen Yao,Meng Li,Kunmeng Liu,Hao Hu,Shengpeng Wang,Yitao Wang 고려인삼학회 2022 Journal of Ginseng Research Vol.46 No.1

Ginseng is an international herb that has been used for thousands of years. Two species most commonly applied and investigated in the ginseng family are Asian ginseng and American ginseng. The number of randomized controlled clinical trials (RCTs) has conspicuously increased, driven by the rapid development of ginseng. However, the reporting of RCT items of ginseng is deficient because of different trial designs and reporting formats, which is a challenge for researchers who are looking for the data with high quality and reliability. Thus, this study focused on providing an extensive analysis of these two species and examined the quality of the RCTs, based on the Consolidated Standards of Reporting Trials (CONSORT) guideline. Ninety-one RCTs conducted from 1980 to 2019 that were related to Asian ginseng and American ginseng used singly met our inclusion criteria. We found that the reporting quality of the two species has improved during the past 40 years. Publication date and sample size were significantly associated with the reporting quality. Rigorous RCTs designed for the species of ginseng are warranted, which can shed light on product research and development of ginseng in the future.

Localized evaluation of actuator tracking for real-time hybrid simulation using frequency-domain indices

Weijie Xu,Tong Guo,Cheng Chen 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.62 No.5

Accurate actuator tracking plays an important role in real-time hybrid simulation (RTHS) to ensure accurate and reliable experimental results. Frequency-domain evaluation index (FEI) interprets actuator tracking into amplitude and phase errors thus providing a promising tool for quantitative assessment of real-time hybrid simulation results. Previous applications of FEI successfully evaluated actuator tracking over the entire duration of the tests. In this study, FEI with moving window technique is explored to provide post-experiment localized actuator tracking assessment. Both moving window with and without overlap are investigated through computational simulations. The challenge is discussed for Fourier Transform to satisfy both time domain and frequency resolution for selected length of moving window. The required data window length for accuracy is shown to depend on the natural frequency and structural nonlinearity as well as the ground motion input for both moving windows with and without overlap. Moving window without overlap shows better computational efficiency and has potential for future online evaluation. Moving window with overlap however requires much more computational efforts and is more suitable for post-experiment evaluation. Existing RTHS data from Network Earthquake Engineering Simulation (NEES) is utilized to further demonstrate the effectiveness of the proposed approaches. It is demonstrated that with proper window size, FEI with moving window techniques enable accurate localized evaluation of actuator tracking for real-time hybrid simulation.

Navigation of Mobile Robots Based on Deep Reinforcement Learning: Reward Function Optimization and Knowledge Transfer

Weijie Li,Ming Yue,Jinyong Shangguan,Ye Jin 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.2

This paper presents an end-to-end online learning navigation method based on deep reinforcement learning (DRL) for mobile robots, whose objective is that mobile robots can avoid obstacles to reach the target point in an unknown environment. Specifically, double deep Q-networks (Double DQN), dueling deep Q-networks (Dueling DQN) and prioritized experience replay (PER) are combined to form prioritized experience replay-double dueling deep Q-networks (PER-D3QN) algorithm to realize high-efficiency navigation of mobile robots. Moreover, considering the problem of sparse reward in the traditional reward function, an artificial potential field is introduced into the reward function to guide robots to fulfill the navigation task through the change of potential energy. Furthermore, in order to accelerate the training of mobile robots in complex environment, a knowledge transfer training method is proposed, which migrates the knowledge from simple to complex environment, and quickly learns on the basis of the priori knowledge. Finally, the performance is validated based on a three-dimensional simulator, which shows that the mobile robot can obtain higher rewards and achieve higher success rates and less time for navigation, indicating that the proposed approaches are feasible and efficient.

Large-eddy simulation of low-swirl multi-nozzle combustion with co- and counter-swirling arrays

Weijie Liu,Bing Ge,Shusheng Zang,Huiru Wang 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.1

Large-eddy simulation (LES) of CH 4 -air low-swirl flame was carried out in a multi-nozzle combustor with two burner configurations by using a premixed flamelet model. The multi-nozzle burner includes a co-swirling array where all five nozzles act in the same direction and a counter-swirling array where the center nozzle is in the opposite swirling direction to the outer nozzles. LES results are in good agreement with OH-planar laser-induced florescence data in terms of OH concentrations and combustion progress variables. Numerical results show that the flow of each nozzle is constant before merging. The neighboring flows interact with each other and generate a highvelocity zone with intensive turbulence. The kinetic energy in the interacting region for the co-swirling array is larger than that for the counter-swirling array. After neighboring flow combining, the flow develops into a unified swirling motion similar to a single swirling flow for the co-swirling array, whereas the flow maintains the individual swirling structures for the counter-swirling arrangement. However, the swirling array exerts minimal effect on multi-nozzle combustion in terms of the temperature distributions and combustion progress of premixed low-swirl multi-nozzle flames.

State and Faults Interval Estimations for Discrete-time Linear Systems

Weijie Ren,Shenghui Guo 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.7

This paper concerns state and fault simultaneous interval estimations for discrete-time linear systems with unknown but bounded uncertainties. Unlike most existing works on interval estimation, the system considered in this work is subject to actuator and sensor faults, while bounded uncertainties exist in both components. Thus, the method developed in this paper can be used for more general conditions. First, the considered system is reformulated as a descriptor one through the augmented vector method. An important lemma for descriptor systems is given in a more accurate description and proven in a very simple way. Then, by using the reachability analysis technique, a new proportional-integral observer-based interval estimation method is proposed. The H∞ technique reduces the influences of time-varying actuator faults and uncertainties. To build the zonotope of bounded uncertainties in the residual system, an equivalent description is introduced. Finally, a numerical example and an industrial system are simulated to demonstrate the efficacy and applicability of the developed method.

Synthesis and adsorption properties of chabazite-like zeolites

Weijie Liu,Lei Qian,Zong Chen,Liying Liu 대한환경공학회 2019 대한환경공학회 학술발표논문집 Vol.2019 No.-

Bit-area efficient embedded pseudo-SRAM utilising dual-threshold hybrid 2T gain cell

Weijie Cheng,Yeonbae Chung IET 2014 IET circuits, devices & systems Vol.8 No.2

<P>The design and physical implementation of an embedded memory utilising bit-area efficient hybrid gain cell is presented. The memory cells in this work are composed of a high-threshold NMOS write transistor and a standard-threshold NMOS read transistor. The bit data are stored on the parasitic capacitances within the cells. Owing to the combination of low subthreshold-leakage write device and high mobility read device, this NMOS-based hybrid 2T gain cell exhibits much improved data retention and read performance in a compact bit area. The memory arrays operate with a logic-compatible supply voltage; SRAM-like I/O interface; chip-select-controlled 128-row refresh; and non-destructive read with speed comparable with 6T SRAM, but 65% smaller cell area. Measurement results from a 32 kbit pseudo-SRAM test chip implemented in a 130 nm logic CMOS technology demonstrate the effectiveness of the proposed embedded memory techniques.</P>