Design of Balanced Dual-Band Bandpass Filter with Self-Feedback Structure

Xinwei Chen,Guorui Han,Runbo Ma,Jiangrui Gao,Wenmei Zhang 한국전자통신연구원 2009 ETRI Journal Vol.31 No.4

A balanced dual-band bandpass filter based on λ/2 stepped-impedance resonators and open-loop resonators is proposed in this letter. By employing a type of self-feedback structure, an extra transmission zero is introduced near the common-mode resonance frequency, and the common-mode signal is suppressed. The measured results indicate that the filter can operate in 2.46 GHz and 5.6 GHz bands, and the insertion loss is 1.85 dB and 1.9 dB, respectively. Also, better common-mode suppression is achieved.

A multiple level set method for modeling grain boundary evolution of polycrystalline materials

Zhang, Xinwei,Chen, Jiun-Shyan,Osher, Stanley Techno-Press 2008 Interaction and multiscale mechanics Vol.1 No.2

In this paper, we model grain boundary evolution based on a multiple level set method. Grain boundary migration under a curvature-induced driving force is considered and the level set method is employed to deal with the resulting topological changes of grain structures. The complexity of using a level set method for modeling grain structure evolution is due to its N-phase nature and the associated geometry compatibility constraint. We employ a multiple level set method with a predictor-multicorrectors approach to reduce the gaps in the triple junctions down to the grid resolution level. A ghost cell approach for imposing periodic boundary conditions is introduced without solving a constrained problem with a Lagrange multiplier method or a penalty method. Numerical results for both uniform and random grain structures evolution are presented and the results are compared with the solutions based on a front tracking approach (Chen and Kotta et al. 2004b).

Study on Wheel-Side Drive System with a Single Trailing Arm

Wang Bin,Chen Xinbo,Lyu Hongming,Niu Xinwei 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.5

In order to reduce unsprung mass and ensure driving comfortability, a novel electrical vehicle (EV) drive system, which integrated the wheel-side reducer and a single trailing arm, was studied in this paper. Firstly, the general structure of the drive system was studied, in which the reducer not only worked as a wheel-side reducer but also as the single trailing arm. Then, the transmission power losses were modeled by integrating different load-independent and load-independent models of power losses. Next, the experiment of the power losses test for the wheel-side drive system was conducted, which declared the patterns of power losses of electric motor and the whole drive system. Finally, the power losses of wheel-side reducer based on NEDC are studied, which illustrates oil churning and gear sliding power losses are the main types of transmission power losses. At low rotational velocities, gear friction power losses are larger than oil churning power losses. While at high rotational velocities, oil churning power losses are dominant. The transmission efficiency of the reducer based on NEDC varies among the range of 78 ~ 95 %, which depends on the torque and rotational velocity transmitted from the driving motor to EV’s wheel.

The Structural Adaptation of Aerial Parts of Invasive Alternanthera philoxeroides to Water Regime

Yong Tao,Fang Chen,Kaiyuan Wan,Xinwei Li,Jianqiang Li 한국식물학회 2009 Journal of Plant Biology Vol.52 No.5

Alternanthera philoxeroides has successfully invaded diverse habitats with considerably various water availability, threatening biological diversity in many parts of the world. Because its genetic variation is very low, phenotypic plasticity is believed to be the primary strategy for adapting to the diverse habitats. In the present paper, we investigated the plastic changes of anatomical traits of the aerial parts of A. philoxeroides from flooding to wet then to drought habitat; the results are as follows: A. philoxeroides could change anatomical structures sensitively to adapt to water regime. As a whole, effects of water regime on structures in stem were greater than those in leaf. Except for principal vein diameter and stoma density on leaf surfaces, all other structural traits were significantly affected by water regime. Among which, cuticular wax layer, collenchyma cell wall, phloem fiber cell wall, and hair density on both leaf surfaces thickened significantly with decrease of water availability, whereas, pith cavity and vessel lumen in stem lessened significantly; wet habitat is vital for the spread of A. philoxeroides from flooding to drought habitat and vice versa, because in this habitat, it had the greatest structural variations; when switching from flooding to wet then to drought habitat, the variations of cuticular wax layer, collenchyma cell wall, phloem fiber cell wall, pith cavity area ratio, diameter of vessel lumen, and hair density on both leaf surfaces, played the most important role. These responsive variables contribute most to the adaptation of A. philoxeroides to diverse habitats with considerably various water availability.

Accurate Measurement of Agatston Score Using kVp-Independent Reconstruction Algorithm for Ultra-High-Pitch Sn150 kVp CT

Hu Xi,Tao Xinwei,Zhang Yueqiao,Niu Zhongfeng,Zhang Yong,Allmendinger Thomas,Kuang Yu,Chen Bin 대한영상의학회 2021 Korean Journal of Radiology Vol.22 No.11

Objective: To investigate the accuracy of the Agatston score obtained with the ultra-high-pitch (UHP) acquisition mode using tin-filter spectral shaping (Sn150 kVp) and a kVp-independent reconstruction algorithm to reduce the radiation dose. Materials and Methods: This prospective study included 114 patients (mean ± standard deviation, 60.3 ± 9.8 years; 74 male) who underwent a standard 120 kVp scan and an additional UHP Sn150 kVp scan for coronary artery calcification scoring (CACS). These two datasets were reconstructed using a standard reconstruction algorithm (120 kVp + Qr36d, protocol A; Sn150 kVp + Qr36d, protocol B). In addition, the Sn150 kVp dataset was reconstructed using a kVp-independent reconstruction algorithm (Sn150 kVp + Sa36d, protocol C). The Agatston scores for protocols A and B, as well as protocols A and C, were compared. The agreement between the scores was assessed using the intraclass correlation coefficient (ICC) and the Bland–Altman plot. The radiation doses for the 120 kVp and UHP Sn150 kVp acquisition modes were also compared. Results: No significant difference was observed in the Agatston score for protocols A (median, 63.05; interquartile range [IQR], 0–232.28) and C (median, 60.25; IQR, 0–195.20) (p = 0.060). The mean difference in the Agatston score for protocols A and C was relatively small (-7.82) and with the limits of agreement from -65.20 to 49.56 (ICC = 0.997). The Agatston score for protocol B (median, 34.85; IQR, 0–120.73) was significantly underestimated compared with that for protocol A (p < 0.001). The UHP Sn150 kVp mode facilitated an effective radiation dose reduction by approximately 30% (0.58 vs. 0.82 mSv, p < 0.001) from that associated with the standard 120 kVp mode. Conclusion: The Agatston scores for CACS with the UHP Sn150 kVp mode with a kVp-independent reconstruction algorithm and the standard 120 kVp demonstrated excellent agreement with a small mean difference and narrow agreement limits. The UHP Sn150 kVp mode allowed a significant reduction in the radiation dose.

Design for a Dual-Frequency Antenna-in-Package

Li Li,Liping Han,Guorui Han,Xinwei Chen,Yanfeng Geng,Wenmei Zhang 한국전자통신연구원 2010 ETRI Journal Vol.32 No.4

For an antenna-in-package (AiP), via holes are used to connect the antenna ground and system ground. In this letter, a dual-frequency AiP with a U-slot embedded in the patch is proposed. By properly arranging three via holes under the non-radiating edge, an AiP with two resonant frequencies is realized. Then a U-slot is embedded in the patch to further improve the bandwidth of the AiP. To validate the proposed design, an AiP with the bandwidth of 4.49% at 2.45 GHz and 6.02% at 5.32 GHz is achieved and fabricated. The measured results agree with the simulated results.