Joint Radio and Computational Resource Allocation for NOMA-Based Mobile Edge Computing in Heterogeneous Networks

Song, Zhengyu,Liu, Yuanwei,Sun, Xin IEEE 2018 IEEE COMMUNICATIONS LETTERS Vol.22 No.12

<P>A joint radio and computational resource allocation problem is investigated for non-orthogonal multiple access (NOMA)-based mobile edge computing (MEC) in heterogeneous networks (HetNets). The aim is to minimize the energy consumption of all users under the task execution latency constraint with partial task offloading. Due to the non-convexity of the formulated problem, we propose an iterative algorithm by decomposing the optimization problem into two subproblems, where the computational resource allocation is a convex optimization problem, and the uplink power allocation is solved by the sequential convex programming. Simulation results reveal that the partial offloading is superior to local computing-only and full offloading-only and NOMA-based MEC outperforms the orthogonal multiple access-based MEC in HetNets.</P>

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.

Anticorrosion and antibiofouling performance of in-situ prepared layered double hydroxide coating modified by sodium pyrithione on aluminum alloy 7075

Wenyuan Jian,Zhengyu Jin,Jing Yang,Guozhe Meng,Hongfang Liu,Hongwei Liu 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.113 No.-

The anticorrosion and antibiofouling of marine engineering equipments have strong demands, especiallyfor antibiofouling. In this work, an in-situ growth layered double hydroxide (LDH) coating on aluminumalloys (AA) 7075 was prepared and then modified by sodium pyrithione (SPT) to increase the anticorrosionand antibiofouling performance. Results indicated that CoAl-LDHs and CoAl-LDHs-SPT coatings hadbeen successfully prepared according to TEM, XRD, XPS, Raman spectra, and SEM analysis results. The(0 1 2) plane of LDHs with a interplanar spacing of 0.26 nm was recognized from TEM images. The contentof SPT in CoAl-LDHs-SPT is 38.79 wt.%. Electrochemical impedance spectroscopy (EIS) and polarizationcurvies demonstrate that the corrosion resistance of AA 7075 was largely improved in the presence ofCoAl-LDHs and CoAl-LDHs-SPT coatings while the anticorrosion performance of CoAl-LDHs-SPT coatingwas better. The corrosion resistance of Co-Al LDHs-SPT coating increased by about two orders of magnitudecompared with the bare AA 7075. The surface analysis results show that only a few Pseudomonasaeruginosa and Spirulina cells attached to the CoAl-LDHs coating surface, and no biofouling cells wereobserved for the CoAl-LDHs-SPT coating. Co-Al LDHs-SPT coating possessed the best anticorrosion andantibiofouling properties due to the presence of SPT compared with the CoAl-LDHs coating.

A Model Predictive Current Control Based on Adaline Neural Network for PMSM

Li Hongfeng,Liu Zhengyu,Shao Jianyu 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.2

The parameter mismatch seriously affects the control performance of the model predictive current control (MPCC). Aiming at improving the parameter robustness of MPCC, a MPCC method based on Adaline neural network for permanent magnet synchronous motor (PMSM) is established. First, the parameters sensitivity analysis of PMSM incremental current prediction model is carried out that eliminates effects of rotor flux linkage mismatch and resistance mismatch. Therefore, a new incremental current prediction model is built, which does not require rotor flux and resistance parameters. Second, based on the above model, Adaline neural network strategy is introduced to identify the inductance parameters which has a variable momentum to improve accuracy. Then, the strategy proposed in this paper has strong robustness to parameter mismatch. Finally, experiment results verify that the proposed method can effectively improve the parameter robustness.

Blooms of the woloszynskioid dinoflagellate Tovellia diexiensis sp. nov. (Dinophyceae) in Baishihai Lake at the eastern edge of Tibetan Plateau

Qi Zhang,Huan Zhu,Zhengyu Hu,Guoxiang Liu 한국조류학회I 2016 ALGAE Vol.31 No.3

Freshwater red tides due to dinoflagellates have caused spectacular and regular “summer reddening” in recent years in Baishihai Lake, a temperate, meromictic, meso- or oligotrophic, high-altitude, landslide-dammed, deep lake located at the eastern edge of Tibetan Plateau in China. Based on morphological and molecular analyses, the causative organism has been identified as a new woloszynskioid dinoflagellate, Tovellia diexiensis Q. Zhang et G. X. Liu sp. nov. The vegetative cells are 20–32 μm long and 16–24 μm wide. They have a hemispherical episome and a broadly rounded hyposome with a short characteristic antapical spine. Usually cells are bright red due to the presence of numerous red-pigmented bodies, which often masked the yellowish green discoid chloroplasts. The amphiesma of motile cells comprise mainly quadrilateral, pentagonal or hexagonal thin plates, arranged in 4–5 latitudinal series on the episome, 1 in the cingulum and 4 on the hyposome. Molecular phylogenies based on small subunit ribosomal DNA and large subunit ribosomal DNA (LSU) indicate T. diexiensis from Baishihai Lake to belong to the family Tovelliaceae, which was monophyletic in our LSU phylogenies. During the bloom-forming period in 2005, cell density of T. diexiensis reached 9.15 × 105 cells L−1. Astaxanthin and its diester were found to be the major pigments in T. diexiensis, resulting in a characteristic blood-red color of the water in Baishihai Lake.

Blooms of the woloszynskioid dinoflagellate Tovellia diexiensis sp. nov. (Dinophyceae) in Baishihai Lake at the eastern edge of Tibetan Plateau

Zhang, Qi,Zhu, Huan,Hu, Zhengyu,Liu, Guoxiang The Korean Society of Phycology 2016 ALGAE Vol.31 No.3

Freshwater red tides due to dinoflagellates have caused spectacular and regular “summer reddening” in recent years in Baishihai Lake, a temperate, meromictic, meso- or oligotrophic, high-altitude, landslide-dammed, deep lake located at the eastern edge of Tibetan Plateau in China. Based on morphological and molecular analyses, the causative organism has been identified as a new woloszynskioid dinoflagellate, Tovellia diexiensis Q. Zhang et G. X. Liu sp. nov. The vegetative cells are 20-32 μm long and 16-24 μm wide. They have a hemispherical episome and a broadly rounded hyposome with a short characteristic antapical spine. Usually cells are bright red due to the presence of numerous red-pigmented bodies, which often masked the yellowish green discoid chloroplasts. The amphiesma of motile cells comprise mainly quadrilateral, pentagonal or hexagonal thin plates, arranged in 4-5 latitudinal series on the episome, 1 in the cingulum and 4 on the hyposome. Molecular phylogenies based on small subunit ribosomal DNA and large subunit ribosomal DNA (LSU) indicate T. diexiensis from Baishihai Lake to belong to the family Tovelliaceae, which was monophyletic in our LSU phylogenies. During the bloom-forming period in 2005, cell density of T. diexiensis reached 9.15 × 10⁵ cells L⁻¹. Astaxanthin and its diester were found to be the major pigments in T. diexiensis, resulting in a characteristic blood-red color of the water in Baishihai Lake.