Co-DDTMA : Cooperative Distributed TDMA for Vehicular Networks

Zhen Chen,Zhengyu Liu,Jianghong Han,Songhua Hu,Yang Lu 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.2

In recent years, Vehicular Ad Hoc Networks (VANET) has experienced a rapid development due to the advancement of wireless communication technologies, and now emerges as a promising way to provide road safety, traffic efficiency and infotainment applications. However, it is a challenge to design a reliable and efficient Medium Access Control (MAC) protocol for VANET due to its frequent topology changes and unreliable wireless links. Cooperative communication, on the other hand, can enhance the reliability of wireless links by exploiting the broadcast nature of the wireless communication. A cooperative scheme for MAC is proposed for VANET in this paper, referred to as Cooperative Distributed TDMA (Co-DTDMA). In the Co-DTDMA, neighboring nodes utilize its idle slots for cooperatively retransmitting a packet which has failed to reach the destination. Since the cooperative retransmission is conducted in node's own idle slot, the proposed scheme does not interrupt the normal transmission. Both theoretical analysis and simulation results demonstrate that the proposed scheme greatly increases the probability of successful packet transmission and decreases the packet transmission delay.

Orthotropic Analysis of Steel Deck–Girder–Rib Systems Subjected to Transverse Load

Mu Chen,Jianghong Xue,Ping Li,Fusong Jin 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.3

As one of the advanced modern techniques, orthotropic steel decks are widely used in bridge engineering. Because of its structural complexity, theoretical analysis of mechanical performances of the orthotropic steel bridge deck is very diffi cult. Therefore, in the past 50 years, a series of experiments and fi nite element analysis have been used to obtain the information. A steel deck–girder–rib bridge system subjected to the transverse load is investigated in this paper. The bridge deck is laid on four simply-supported girders at the four edges and is reinforced by ribs in longitudinal direction. The longitudinally stiff ened deck is idealized as an orthotropic plate. The equivalent material properties in the longitudinal and breadth directions of the orthotropic plate are evaluated using micro-mechanics of composite material by treating the ribs as reinforcing fi ber-beams. Governing equations for the deck–girder–rib bridge systems are established and are solved using Ritz method. The analytical solutions are substantiated by comparing with the classic solutions of an isotropic deck with fi xed ends and with the fi nite element predictions. The analytical approach presented in this paper eliminates the very intricate and arduous kinematics study among deck–girder–rib and allows the bridge engineer to fast and convenient estimate the deformation in an orthotropic bridge deck.

OsSPL13 controls grain size in cultivated rice

Si, Lizhen,Chen, Jiaying,Huang, Xuehui,Gong, Hao,Luo, Jianghong,Hou, Qingqing,Zhou, Taoying,Lu, Tingting,Zhu, Jingjie,Shangguan, Yingying,Chen, Erwang,Gong, Chengxiang,Zhao, Qiang,Jing, Yufeng,Zhao, Y Nature Publishing Group, a division of Macmillan P 2016 Nature genetics Vol.48 No.4

<P>Although genetic diversity has a cardinal role in domestication, abundant natural allelic variations across the rice genome that cause agronomically important differences between diverse varieties have not been fully explored. Here we implement an approach integrating genome-wide association testing with functional analysis on grain size in a diverse rice population. We report that a major quantitative trait locus, GLW7, encoding the plant-specific transcription factor OsSPL13, positively regulates cell size in the grain hull, resulting in enhanced rice grain length and yield. We determine that a tandem-repeat sequence in the 5'UTR of OsSPL13 alters its expression by affecting transcription and translation and that high expression of OsSPL13 is associated with large grains in tropical japonica rice. Further analysis indicates that the large-grain allele of GLW7 in tropical japonica rice was introgressed from indica varieties under artificial selection. Our study demonstrates that new genes can be effectively identified on the basis of genome-wide association data.</P>

A Generalized Markov Chain Model for IEEE 802.11 Distributed Coordination Function

( Ping Zhong ),( Jianghong Shi ),( Yuxiang Zhuang ),( Huihuang Chen ),( Xuemin Hong ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.2

To improve the accuracy and enhance the applicability of existing models, this paper proposes a generalized Markov chain model for IEEE 802.11 Distributed Coordination Function (DCF) under the widely adopted assumption of ideal transmission channel. The IEEE 802.11 DCF is modeled by a two dimensional Markov chain, which takes into account unsaturated traffic, backoff freezing, retry limits, the difference between maximum retransmission count and maximum backoff exponent, and limited buffer size based on the M/G/1/K queuing model. We show that existing models can be treated as special cases of the proposed generalized model. Furthermore, simulation results validate the accuracy of the proposed model.

Feasibility Study of Radiation Dose Reduction in Adult Female Pelvic CT Scan with Low Tube-Voltage and Adaptive Statistical Iterative Reconstruction

Xinlian Wang,Wen He,Jianghong Chen,Zhihai Hu,Liqin Zhao 대한영상의학회 2015 Korean Journal of Radiology Vol.16 No.5

To evaluate image quality of female pelvic computed tomography (CT) scans reconstructed with the adaptive statistical iterative reconstruction (ASIR) technique combined with low tube-voltage and to explore the feasibility of its clinical application. Ninety-four patients were divided into two groups. The study group used 100 kVp, and images were reconstructed with 30%, 50%, 70%, and 90% ASIR. The control group used 120 kVp, and images were reconstructed with 30% ASIR. The noise index was 15 for the study group and 11 for the control group. The CT values and noise levels of different tissues were measured. The contrast to noise ratio (CNR) was calculated. A subjective evaluation was carried out by two experienced radiologists. The CT dose index volume (CTDIvol) was recorded. A 44.7% reduction in CTDIvol was observed in the study group (8.18 ± 3.58 mGy) compared with that in the control group (14.78 ± 6.15 mGy). No significant differences were observed in the tissue noise levels and CNR values between the 70% ASIR group and the control group (p = 0.068–1.000). The subjective scores indicated that visibility of small structures, diagnostic confidence, and the overall image quality score in the 70% ASIR group was the best, and were similar to those in the control group (1.87 vs. 1.79, 1.26 vs. 1.28, and 4.53 vs. 4.57; p = 0.122–0.585). No significant difference in diagnostic accuracy was detected between the study group and the control group (42/47 vs. 43/47, p = 1.000). Low tube-voltage combined with automatic tube current modulation and 70% ASIR allowed the low CT radiation dose to be reduced by 44.7% without losing image quality on female pelvic scan.

Optimal Power Allocation for Wireless Uplink Transmissions Using Successive Interference Cancellation

( Liaoyuan Wu ),( Yamei Wang ),( Jianghong Han ),( Wenqiang Chen ),( Lusheng Wang ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.5

Successive interference cancellation (SIC) is considered to be a promising technique to mitigate multi-user interference and achieve concurrent uplink transmissions, but the optimal power allocation (PA) issue for SIC users is not well addressed. In this article, we focus on the optimization of the PA ratio of users on an SIC channel and analytically obtain the optimal PA ratio with regard to the signal-to-interference-plus-noise ratio (SINR) threshold for successful demodulation and the sustainable demodulation error rate. Then, we design an efficient resource allocation (RA) scheme using the obtained optimal PA ratio. Finally, we compare the proposal with the near-optimum RA obtained by a simulated annealing search and the RA scheme with random PA. Simulation results show that our proposal achieves a performance close to the near-optimum and much higher performance than the random scheme in terms of total utility and Jain`s fairness index. To demonstrate the applicability of our proposal, we also simulate the proposal in various network paradigms, including wireless local area network, body area network, and vehicular ad hoc network.

A Heuristic Algorithm for Optimal Facility Placement in Mobile Edge Networks

( Jiping Jiao ),( Lingyu Chen ),( Xuemin Hong ),( Jianghong Shi ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.7

Installing caching and computing facilities in mobile edge networks is a promising solution to cope with the challenging capacity and delay requirements imposed on future mobile communication systems. The problem of optimal facility placement in mobile edge networks has not been fully studied in the literature. This is a non-trivial problem because the mobile edge network has a unidirectional topology, making existing solutions inapplicable. This paper considers the problem of optimal placement of a fixed number of facilities in a mobile edge network with an arbitrary tree topology and an arbitrary demand distribution. A low-complexity sequential algorithm is proposed and proved to be convergent and optimal in some cases. The complexity of the algorithm is shown to be O(H²γ), where H is the height of tree and γ is the number of facilities. Simulation results confirm that the proposed algorithm is effective in producing near-optimal solution

On the Controlled-spin Intensity Method For the Tangentially-fired Furnaces

Ding Shifa,Kuang Jianghong,Liu Pingyuan,Chen Chaosong,Hu Xingsheng,Cao Handing,Xu Jinyuan 한국전산유체공학회 2003 한국전산유체공학회 학술대회논문집 Vol.2003 No.10

Locating QTLs controlling overwintering seedling rate in perennial glutinous rice 89-1 (Oryza sativa L.)

Xiaoshu Deng,Lu Gan,Yan Liu,Ancai Luo,Liang Jin,Jiao Chen,Ruyu Tang,Lixia Lei,Jianghong Tang,Jiani Zhang,Zhengwu Zhao 한국유전학회 2018 Genes & Genomics Vol.40 No.12

A new cold tolerant germplasm resource named glutinous rice 89-1 (Gr89-1, Oryza sativa L.) can overwinter using axillary buds, with these buds being ratooned the following year. The overwintering seedling rate (OSR) is an important factor for evaluating cold tolerance. Many quantitative trait loci (QTLs) controlling cold tolerance at different growth stages in rice have been identified, with some of these QTLs being successfully cloned. However, no QTLs conferring to the OSR trait have been located in the perennial O. sativa L. To identify QTLs associated with OSR and to evaluate cold tolerance. 286 F12 recombinant inbred lines (RILs) derived from a cross between the cold tolerant variety Gr89-1 and cold sensitive variety Shuhui527 (SH527) were used. A total of 198 polymorphic simple sequence repeat (SSR) markers that were distributed uniformly on 12 chromosomes were used to construct the linkage map. The gene ontology (GO) annotation of the major QTL was performed through the rice genome annotation project system. Three main-effect QTLs (qOSR2, qOSR3, and qOSR8) were detected and mapped on chromosomes 2, 3, and 8, respectively. These QTLs were located in the interval of RM14208 (35,160,202 base pairs (bp))–RM208 (35,520,147 bp), RM218 (8,375,236 bp)–RM232 (9,755,778 bp), and RM5891 (24,626,930 bp)–RM23608 (25,355,519 bp), and explained 19.6%, 9.3%, and 11.8% of the phenotypic variations, respectively. The qOSR2 QTL displayed the largest effect, with a logarithm of odds score (LOD) of 5.5. A total of 47 candidate genes on the qOSR2 locus were associated with 219 GO terms. Among these candidate genes, 11 were related to cell membrane, 7 were associated with cold stress, and 3 were involved in response to stress and biotic stimulus. OsPIP1;3 was the only one candidate gene related to stress, biotic stimulus, cold stress, and encoding a cell membrane protein. After QTL mapping, a total of three main-effect QTLs—qOSR2, qOSR3, and qOSR8—were detected on chromosomes 2, 3, and 8, respectively. Among these, qOSR2 explained the highest phenotypic variance. All the QTLs elite traits come from the cold resistance parent Gr89-1. OsPIP1;3 might be a candidate gene of qOSR2.