Energy Efficiency of Distributed Massive MIMO Systems

He, Chunlong,Yin, Jiajia,He, Yejun,Huang, Min,Zhao, Bo The Korea Institute of Information and Commucation 2016 Journal of communications and networks Vol.18 No.4

In this paper, we investigate energy efficiency (EE) of the traditional co-located and the distributed massive multiple-input multiple-output (MIMO) systems. First, we derive an approximate EE expression for both the idealistic and the realistic power consumption models. Then an optimal energy-efficient remote access unit (RAU) selection algorithm based on the distance between the mobile stations (MSs) and the RAUs are developed to maximize the EE for the downlink distributed massive MIMO systems under the realistic power consumption model. Numerical results show that the EE of the distributed massive MIMO systems is larger than the co-located massive MIMO systems under both the idealistic and realistic power consumption models, and the optimal EE can be obtained by the developed energy-efficient RAU selection algorithm.

Energy Efficiency of Distributed Massive MIMO Systems

Chunlong He,Jiajia Yin,Yejun He,Min Huang,Bo Zhao 한국통신학회 2016 Journal of communications and networks Vol.18 No.4

In this paper, we investigate energy efficiency (EE) of thetraditional co-located and the distributed massive multiple-inputmultiple-output (MIMO) systems. First, we derive an approximateEE expression for both the idealistic and the realistic power consumptionmodels. Then an optimal energy-efficient remote accessunit (RAU) selection algorithm based on the distance between themobile stations (MSs) and the RAUs are developed to maximizethe EE for the downlink distributedmassive MIMO systems underthe realistic power consumption model. Numerical results showthat the EE of the distributedmassiveMIMOsystems is larger thanthe co-locatedmassiveMIMOsystems under both the idealistic andrealistic power consumptionmodels, and the optimal EE can be obtainedby the developed energy-efficient RAU selection algorithm.

Hydroxide MgSn(OH)6: A Promising New Photocatalyst for Methyl Orange Degradation

Jiajia Tao,Zhaoqi Sun,Miao Zhang,Gang He,Xiaoshuang Chen 대한금속·재료학회 2017 ELECTRONIC MATERIALS LETTERS Vol.13 No.4

Highly crystalline hydroxide MgSn(OH)6 (MHS) polyhedral particleswere synthesized by changing reaction time (10, 15 and 20 h) in ahydrothermal process. The structural and morphological poperties ofobtained samples were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM), and UV-vis diffuse reflectancespectroscopy (DRS). The photocatalytic activity of the MHS wasfurther evaluated by the degradation of methyl orange (MO) underultraviolet (UV) light illumination. Compared with commercial TiO2(Degussa P25), the MHS prepared for 15 h showed similar degradationefficiency of methyl orange (MO), mainly due to its higher specificsurface area (55 m2g−1) and better optical properties.

Anaerobic membrane bioreactors for wastewater treatment: mechanisms, fouling control, novel configurations, and future perspectives

Jiajia Li,Jinyuan Jiang,Junchao Li,Changjun He,Yong Luo,Lihong Wei 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.1

As the world focuses on reducing greenhouse gas emissions and recovering energy from sewage, technologies that can recover energy and reuse wastewater are becoming increasingly important. Anaerobic membrane bioreactor (AnMBR) technology has recently attracted attention, as it can achieve energy recovery and yields high-quality effluent. However, the large-scale commercial application of AnMBRs requires that certain barriers be overcome, including membrane pollution and dissolved methane recovery. In this review article, we summarize the basic principles of anaerobic wastewater digestion and discuss the excellent performance of AnMBRs for wastewater treatment. Various factors, membrane types, and pollution are discussed, and control strategies for dealing with membrane pollution are put forward. In addition, a variety of new AnMBRs are described that may better control membrane pollution. Finally, future research directions for AnMBRs are presented to promote the large-scale integrated application of AnMBRs for industrial wastewater treatment.

Three-dimensional trajectory tracking for underactuated AUVs with bio-inspired velocity regulation

Jiajia Zhou,Dingqi Ye,Junpeng Zhao,Dongxu He 대한조선학회 2018 International Journal of Naval Architecture and Oc Vol.10 No.3

This paper attempts to address the motion parameter skip problem associated with three-dimensional trajectory tracking of an underactuated Autonomous Underwater Vehicle (AUV) using backstepping-based control, due to the unsmoothness of tracking trajectory. Through kinematics concepts, a three-dimensional dynamic velocity regulation controller is derived. This controller makes use of the surge and angular velocity errors with bio-inspired models and backstepping techniques. It overcomes the frequently occurring problem of parameter skip at inflection point existing in backstepping tracking control method and increases system robustness. Moreover, the proposed method can effectively avoid the singularity problem in backstepping control of virtual velocity error. The control system is proved to be uniformly ultimately bounded using Lyapunov stability theory. Simulation results illustrate the effectiveness and efficiency of the developed controller, which can realize accurate three-dimensional trajectory tracking for an underactuated AUV with constant external disturbances.

A Novel Xylanase from Streptomyces sp. FA1: Purification, Characterization, Identification, and Heterologous Expression

Jie He,Lingqia Su,Xiaojun Sun,Jiajia Fu,Jian Chen,Jing Wu 한국생물공학회 2014 Biotechnology and Bioprocess Engineering Vol.19 No.1

A xylanase (XynA) was purified from the culturemedium of Streptomyces sp. FA1, which was previouslyisolated from a bamboo retting system. XynA had amolecular mass of 43 kDa, displayed maximal activity atpH 5.5, retained 41% of its maximal activity at pH 11.0,and was stable over a wide pH range (3.0 ~ 11.0). PurifiedXynA was subjected to peptide mass fingerprinting, whichled to the cloning of the xynA gene. The xynA gene, whichencodes a mature protein of 436 amino acids, washeterologously expressed in E. coli BL21(DE3). The activityin the culture medium could reach 213.5 U/mL, which was11.2-fold higher than that produced by Streptomyces sp. FA1. BLAST searching revealed that full-length XynAshares less than 90% identity with most of its homologues,whereas amino acids 48-436 of the enzyme share 97%identity with an open reading frame encoding a putativefull-length mature xylanase from Streptomyces tendae. Thetruncated xynA gene, xynA48-436, was cloned and expressedin E. coli, however, no xylanase activity could be detectedin the culture medium. Based on these results, it is suggestedthat XynA is a new member of glycoside hydrolasesfamily10 with exceptional catalytic efficiency at alkalinepH.

Three-dimensional trajectory tracking for underactuated AUVs with bio-inspired velocity regulation

Zhou, Jiajia,Ye, Dingqi,Zhao, Junpeng,He, Dongxu The Society of Naval Architects of Korea 2018 International Journal of Naval Architecture and Oc Vol.10 No.3

This paper attempts to address the motion parameter skip problem associated with three-dimensional trajectory tracking of an underactuated Autonomous Underwater Vehicle (AUV) using backstepping-based control, due to the unsmoothness of tracking trajectory. Through kinematics concepts, a three-dimensional dynamic velocity regulation controller is derived. This controller makes use of the surge and angular velocity errors with bio-inspired models and backstepping techniques. It overcomes the frequently occurring problem of parameter skip at inflection point existing in backstepping tracking control method and increases system robustness. Moreover, the proposed method can effectively avoid the singularity problem in backstepping control of virtual velocity error. The control system is proved to be uniformly ultimately bounded using Lyapunov stability theory. Simulation results illustrate the effectiveness and efficiency of the developed controller, which can realize accurate three-dimensional trajectory tracking for an underactuated AUV with constant external disturbances.

Resource Allocation for Relay-Aided Cooperative Systems Based on Multi-Objective Optimization

( Runze Wu ),( Jiajia Zhu ),( Hailin Hu ),( Yanhua He ),( Liangrui Tang ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.5

This paper studies resource allocation schemes for the relay-aided cooperative system consisting of multiple source-destination pairs and decode-forward (DF) relays. Specially, relaying selection, multisubcarrier pairing and assignment, and power allocation are investigated jointly. We consider a combinatorial optimization problem on quality of experience (QoE) and energy consumption based on relay-aided cooperative system. For providing better QoE and lower energy consumption we formulate a multi-objective optimization problem to maximize the total mean opinion score (MOS) value and minimize the total power consumption. To this end, we employ the nondominated sorting genetic algorithm version II (NSGA-II) and obtain sets of Pareto optimal solutions. Specially, two formulas are devised for the optimal solutions of the multi-objective optimization problems with and without a service priority constraint. Moreover, simulation results show that the proposed schemes are superior to the existing ones.

Effect of TiO2@Carbon Nanotubes and Praseodymium on the Microhardness and Corrosion Properties of AZ91 Alloy

Qianwen Ran,Hong Yan,Jiajia He,Ning Li,Yushun Lei 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8

Effect of 1 wt% TiO2@carbon nanotubes (TiO2@CNTs) and 1 wt% praseodymium (Pr) on the microhardness and corrosionproperties of AZ91 magnesium alloy were discussed. The microhardness test, electrochemistry test that AZ91 magnesiumalloy with 1 wt% TiO2@CNTs and 1 wt% Pr addition exhibits excellent microhardness (111 HV), low corrosion currentdensity (0.165 mA·cm−2), and low polarization resistance (537.15 Ω·cm2) compared with AZ91 magnesium alloy (89 HV,0.184 mA·cm−2, 261.06 Ω·cm2). After 1 wt% TiO2@CNTs and 1 wt% Pr added to AZ91, the average crystallite size wasreduced and microhardness was increased. Additionally, the Al11Pr3phase formed by the combination of Pr and Al transformedthe morphology of β-Mg17Al12 phase into weeny particles and decreased the volume fraction of β-Mg17Al12 phase. The reduction and refinement of cathode phase (β-Mg17Al12 phase) weakened the micro-galvanic corrosion and sloweddown the corrosion rate.

Synthesis, and antioxidant, thrombin-inhibitory, and anticancer activities of hydroxybenzamide derivatives

Jin-Rui Wei,Kun Liu,Faquan Lin,Chunping He,Xuan Luo,Jiajia Zou,Wei He,Wenqian Nong,Cui-Wu Lin 한국응용생명화학회 2016 Applied Biological Chemistry (Appl Biol Chem) Vol.59 No.2

Four hydroxybenzamide derivatives were synthesized from protocatechuic acid. The antioxidant activities of these derivatives were evaluated in vitro using DPPH radical scavenging and reducing power assays. In addition, these compounds were subjected to a chromogenic thrombin-inhibitory assay using Chromozym-TH as the substrate. The anticancer effects of these derivatives were also investigated using the MTT assay in three human cancer cell lines. Four derivatives exhibited excellent DPPH radical scavenging activity and redox potential. Their highly inhibitory effect against thrombin may allow them to be utilized as novel micromolecule thrombin inhibitors. Furthermore, four derivatives demonstrated different inhibitory activities in three human cancer cell lines but showed minimal harmful effects on normal HUVEC cells. Therefore, hydroxybenzamide derivatives indicate the superior antioxidant, thrombin-inhibitory, and anticancer activities along with the excellent biocompatibility, which have the potential application in therapeutic interventions and disease prevention of cancer, thrombotic diseases, and aging.