A Data-Consistency Scheme for the Distributed-Cache Storage of the Memcached System

Jianwei Liao,Xiaoning Peng 한국정보과학회 2017 Journal of Computing Science and Engineering Vol.11 No.3

Memcached, commonly used to speed up the data access in big-data and Internet-web applications, is a system software of the distributed-cache mechanism. But it is subject to the severe challenge of the loss of recently uncommitted updates in the case where the Memcached servers crash due to some reason. Although the replica scheme and the disk-log-based replay mechanism have been proposed to overcome this problem, they generate either the overhead of the replica synchronization or the persistent-storage overhead that is caused by flushing related logs. This paper proposes a scheme of backing up the write requests (i.e., set and add) on the Memcached client side, to reduce the overhead resulting from the making of disk-log records or performing the replica consistency. If the Memcached server fails, a timestamp-based recovery mechanism is then introduced to replay the write requests (buffered by relevant clients), for regaining the lostdata updates on the rebooted Memcached server, thereby meeting the data-consistency requirement. More importantly, compared with the mechanism of logging the write requests to the persistent storage of the master server and the serverreplication scheme, the newly proposed approach of backing up the logs on the client side can greatly decrease the time overhead by up to 116.8% when processing the write workloads.

A Data-Consistency Scheme for the Distributed-Cache Storage of the Memcached System

Liao, Jianwei,Peng, Xiaoning Korean Institute of Information Scientists and Eng 2017 Journal of Computing Science and Engineering Vol.11 No.3

Memcached, commonly used to speed up the data access in big-data and Internet-web applications, is a system software of the distributed-cache mechanism. But it is subject to the severe challenge of the loss of recently uncommitted updates in the case where the Memcached servers crash due to some reason. Although the replica scheme and the disk-log-based replay mechanism have been proposed to overcome this problem, they generate either the overhead of the replica synchronization or the persistent-storage overhead that is caused by flushing related logs. This paper proposes a scheme of backing up the write requests (i.e., set and add) on the Memcached client side, to reduce the overhead resulting from the making of disk-log records or performing the replica consistency. If the Memcached server fails, a timestamp-based recovery mechanism is then introduced to replay the write requests (buffered by relevant clients), for regaining the lost-data updates on the rebooted Memcached server, thereby meeting the data-consistency requirement. More importantly, compared with the mechanism of logging the write requests to the persistent storage of the master server and the server-replication scheme, the newly proposed approach of backing up the logs on the client side can greatly decrease the time overhead by up to 116.8% when processing the write workloads.

A Cut‑Out Strategy for Wind Turbines that Ensures Low‑Voltage Ride‑Through Capability

Aiguo Tan,Zhihan Tang,Xianbo Sun,Jianwei Zhong,Honghua Liao,Haibing Fang 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.4

To ensure the dynamic stability of the system and improve low-voltage ride-through (LVRT) capability, this study presents a cut-out strategy for doubly-fed induction generator (DFIG) wind turbines that combines reactive power output with asynchronous load reduction. This strategy reduces the risk of the large-scale disconnection of DFIGs in a wind farm by regulating the reactive power output of DFIGs in the wind farm and removing DFIGs in an asynchronous state based on the reduction ratio. Simulation results demonstrate that the implementation of this strategy can help increase the voltage at the point of common coupling and the LVRT time for a wind farm.

Genetic Algorithm‑Based Analysis of the Efects of an Additional Damping Controller for a Doubly Fed Induction Generator

Aiguo Tan,Zhihan Tang,Xianbo Sun,Jianwei Zhong,Honghua Liao,Haibing Fang 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.4

In view of the problem that large-scale and high-penetration wind power access may weaken the stability of small interference in the power grid, this study proposes a novel additional damping controllers for the doubly-fed induction generator (DFIG) based on the genetic algorithm. A DFIG model and its control system is built, and the parameters of the controller are tuned using the genetic algorithm to optimize the control efect. Based on Western System Coordinating Council (WSCC) 3-machine 9-node system, multi-scenario simulation results verifes that the additional damping controller proposed in this study performs better to suppress the low-frequency oscillation than the power system stabilizer (PSS) installed on the synchronous generators which are farther to the disturbance point. Meanwhile, the proposed strategy is compared with the reactive power modulation control, which can provide a reference for engineering applications of an added DFIG damping controller.

Impact of NR1I2, adenosine triphosphateebinding cassette transporters genetic polymorphisms on the pharmacokinetics of ginsenoside compound K in healthy Chinese volunteers

Luping Zhou,Lulu Chen,Yaqin Wang,Jie Huang,Guo Ping Yang,Zhi-Rong Tang,Yicheng Wang,Jianwei Liao,Gan Zhou,Kai-hua Wei,Zhenyu Li,Dongsheng Ouyang 고려인삼학회 2019 Journal of Ginseng Research Vol.43 No.3

Background: Ginsenoside compound K (CK) is a promising drug candidate for rheumatoid arthritis. Thisstudy examined the impact of polymorphisms in NR1I2, adenosine triphosphateebinding cassette (ABC)transporter genes on the pharmacokinetics of CK in healthy Chinese individuals. Methods: Forty-two targeted variants in seven genes were genotyped in 54 participants using SequenomMassARRAY system to investigate their association with major pharmacokinetic parameters of CK and itsmetabolite 20(S)-protopanaxadiol (PPD). Subsequently, molecular docking was simulated using theAutoDock Vina program. Results: ABCC4 rs1751034 TT and rs1189437 TT were associated with increased exposure of CK anddecreased exposure of 20(S)-PPD, whereas CFTR rs4148688 heterozygous carriers had the lowestmaximum concentration (Cmax) of CK. The area under the curve from zero to the time of the lastquantifiable concentration (AUClast) of CK was decreased in NR1I2 rs1464602 and rs2472682 homozygouscarriers, while Cmax was significantly reduced only in rs2472682. ABCC4 rs1151471 and CFTR rs2283054influenced the pharmacokinetics of 20(S)-PPD. In addition, several variations in ABCC2, ABCC4, CFTR, andNR1I2 had minor effects on the pharmacokinetics of CK. Quality of the best homology model of multidrugresistance protein 4 (MRP4) was assessed, and the ligand interaction plot showed the mode of interactionof CK with different MRP4 residues. Conlusion: ABCC4 rs1751034 and rs1189437 affected the pharmacokinetics of both CK and 20(S)-PPD. NR1I2 rs1464602 and rs2472682 were only associated with the pharmacokinetics of CK. Thus, thesehereditary variances could partly explain the interindividual differences in the pharmacokinetics of CK.

Backbone Conformation Tuning of Carboxylate-Functionalized Wide Band Gap Polymers for Efficient Non-Fullerene Organic Solar Cells

Chen, Jianhua,Wang, Lei,Yang, Jie,Yang, Kun,Uddin, Mohammad Afsar,Tang, Yumin,Zhou, Xin,Liao, Qiaogan,Yu, Jianwei,Liu, Bin,Woo, Han Young,Guo, Xugang American Chemical Society 2019 Macromolecules Vol.52 No.1

<P>Two carboxylate-functionalized wide band gap polymers, 2TC-TT-BDTFT and 2T-TTC-BDTFT, which feature a fluorinated benzodithiophene (BDTFT)-<I>alt</I>-2,5-di(thiophen-2-yl)thieno[3,2-<I>b</I>]thiophene (2T-TT) backbone having different carboxylate attaching positions, were designed and synthesized. By variation of the substitution position of carboxylate groups on the 2T-TT unit, the backbone conformation of the designed building blocks 2TC-TT and 2T-TTC and their corresponding donor-acceptor polymers was fine-tuned as demonstrated by single crystal study and DFT calculation, thus yielding a large device performance difference in organic solar cells. As a result of the relatively higher planarity of the 2T-TTC unit in which the two carboxylate groups were attached on the inner thieno[3,2-<I>b</I>]thiophene moiety, the 2T-TTC-BDTFT polymer exhibited a red-shifted UV-vis absorption, stronger aggregation, and improved charge transport property than its polymer analogue 2TC-TT-BDTFT, in which the two outer thiophene rings were functionalized with carboxylate groups. Benefiting from the improved exciton dissociation and charge collection efficiency, better film morphology, and higher photoresponse, non-fullerene organic solar cells based on 2T-TTC-BDTFT:m-ITIC achieved a power conversion efficiency (PCE) of 11.15% with a fill factor (FF) of ∼70%, while the 2TC-TT-BDTFT:m-ITIC cells showed a relatively lower PCE of 9.65% and FF of 59.31%. The much higher FF of 2T-TTC-BDTFT-based solar cells reflects the great merit of the carboxylation on thienothiophene moiety rather than the outer thiophene counterpart. Therefore, the modulation of the carboxylate position on polymer backbones is an efficient strategy to tune the backbone conformation, interchain packing, film morphology, and the resulting optical, electrical, and photovoltaic properties. Moreover, both the 2T-TTC-BDTFT:m-ITIC and 2TC-TT-BDTFT:m-ITIC solar cells showed excellent stability during annealing and long-term storage. These results demonstrate that carboxylate-functionalized 2T-TTC and 2TC-TT have great potentials as a weak electron-accepting building block for wide band gap polymers for high-performance non-fullerene organic solar cells, and the carboxylate position on the polymer backbones is critical for performance improvement of organic photovoltaic devices.</P> [FIG OMISSION]</BR>

Impact of NR1I2, adenosine triphosphate-binding cassette transporters genetic polymorphisms on the pharmacokinetics of ginsenoside compound K in healthy Chinese volunteers

Zhou, Luping,Chen, Lulu,Wang, Yaqin,Huang, Jie,Yang, Guoping,Tan, Zhirong,Wang, Yicheng,Liao, Jianwei,Zhou, Gan,Hu, Kai,Li, Zhenyu,Ouyang, Dongsheng The Korean Society of Ginseng 2019 Journal of Ginseng Research Vol.43 No.3

Background: Ginsenoside compound K (CK) is a promising drug candidate for rheumatoid arthritis. This study examined the impact of polymorphisms in NR1I2, adenosine triphosphate-binding cassette (ABC) transporter genes on the pharmacokinetics of CK in healthy Chinese individuals. Methods: Forty-two targeted variants in seven genes were genotyped in 54 participants using Sequenom MassARRAY system to investigate their association with major pharmacokinetic parameters of CK and its metabolite 20(S)-protopanaxadiol (PPD). Subsequently, molecular docking was simulated using the AutoDock Vina program. Results: ABCC4 rs1751034 TT and rs1189437 TT were associated with increased exposure of CK and decreased exposure of 20(S)-PPD, whereas CFTR rs4148688 heterozygous carriers had the lowest maximum concentration ($C_{max}$) of CK. The area under the curve from zero to the time of the last quantifiable concentration ($AUC_{last}$) of CK was decreased in NR1I2 rs1464602 and rs2472682 homozygous carriers, while $C_{max}$ was significantly reduced only in rs2472682. ABCC4 rs1151471 and CFTR rs2283054 influenced the pharmacokinetics of 20(S)-PPD. In addition, several variations in ABCC2, ABCC4, CFTR, and NR1I2 had minor effects on the pharmacokinetics of CK. Quality of the best homology model of multidrug resistance protein 4 (MRP4) was assessed, and the ligand interaction plot showed the mode of interaction of CK with different MRP4 residues. Conlusion: ABCC4 rs1751034 and rs1189437 affected the pharmacokinetics of both CK and 20(S)-PPD. NR1I2 rs1464602 and rs2472682 were only associated with the pharmacokinetics of CK. Thus, these hereditary variances could partly explain the interindividual differences in the pharmacokinetics of CK.