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A Reduce Task Scheduler for MapReduce with Minimum Transmission Cost Based on Sampling Evaluation
Xia Tang,Lijun Wang,Zhiqiang Geng 보안공학연구지원센터 2015 International Journal of Database Theory and Appli Vol.8 No.1
MapReduce is a popular framework for processing large datasets in parallel over a cluster. It has gained wide attention for its high scalability, reliability and low cost. However, its performance may be degraded by excessive network traffic when processing jobs, for such two problems as data locality in reduce task scheduling and partitioning skew. We propose a Minimum Transmission Cost Reduce task Scheduler (MTCRS) based on sampling evaluation to solve the two problems. The MTCRS takes the waiting time of each reduce task and the transmission cost set as indicators to decide appropriate launching locations for Reduce tasks. The transmission cost set is computed by a mathematical model, in which the parameters are the sizes and the locations of intermediate data partitions generated by Average Reservoir Sampling (ARS) algorithm. The experiments show that the MTCRS reduces network traffic by 8.4% compared with Fair scheduler.
Anti-Rollover Control Based on Stable Zone Partition of Counterbalanced Forklift Trucks
Xia Guang,Xia Yan,Tang Xiwen,Zhao Linfeng,Hu Jinfang 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.6
To improve the anti-rollover capacity of a counterbalanced forklift, a two-stage rollover dynamic model is established on the basis of the forklift structure. Stable zones are divided according to the two-stage lateral load transfer rate: stable region, relatively stable region, dangerous zone and abnormal dangerous zone. An anti-rollover layered control strategy based on stable zone partition is proposed, and different anti-rollover control actuators are selected: dynamic balance weight, anti-rollover cylinder and steering cylinder. Anti-rollover controllers consist of the upper stable region identification controller, the middle-level controller based on model predictive control (MPC) and the lower layer executive controller. The upper stable region identification controller performs stable zone recognition based on the two-stage lateral load transfer rate. The middlelevel MPC controller calculates the required control torque with the body’s lateral angle and yaw rate as the control objectives. The lower layer executive controller controls the balance weight, anti-rollover cylinder and the steering cylinder according to the improved chain incremental allocation method to meet the target control torque. Simulation and real vehicle tests based on MATLAB/Simulink show that the anti-rollover control based on stable zone partition can greatly reduce the risk of forklift rollover and improve the forklift safety.
Formation Tracking Control for Multi-agent Systems: A Wave-equation based Approach
Shu-Xia Tang,Jie Qi,Jing Zhang 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.6
This paper considers the formation tracking control problem of large-scaled Multi-Agent Systems (MAS)for which the model is based on a system of mutually independent wave Partial Differential Equations (PDEs). Thespatial derivatives in the equation correspond to the underlying communication topology of the agents. A leaderfollowermode is employed in the control algorithm, with which the agents on the boundary of PDEs are chosenas leaders knowing the tracking trajectory and all the other agents are followers. Each follower has only the informationof its own relative position and velocity to its topological neighbors. With a designed distributed controller,the formation tracking error is bounded by a constant proportional to the acceleration of the desired trajectory. Robustness of the control law to a perturbation in the velocity measurement is also discussed. Furthermore, somesimulation studies are provided to show the effectiveness of the control algorithm.
Expression of the CXCL12/SDF-1 Chemokine Receptor CXCR7 in Human Brain Tumours
Tang, Tian,Xia, Qing-Jie,Chen, Jian-Bin,Xi, Ming-Rong,Lei, Ding Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.10
Purpose: Receptor 7 (CXCR7) has recently been characterized as a novel receptor for CXCL12/SDF-1 (stromal cell derived factor-1). Given the demonstrated importance of CXCL12/SDF-1 in angiogenesis and tumour metastasis, we hypothesized that CXCR7 may also play a role in tumour pathogenesis. Located in the limited space of the intracranial cavity, any brain tumours can be inherently serious and life-threatening. However, the expression of CXCR7 in pituitary adenoma, neurilemmoma or hemangioblastoma remains to be elucidated. Therefore, we aimed to determine the potential contribution of CXCR7 in the development of brain tumours. Methods: In this study we examined and quantified the mRNA expression of CXCR7 in four different human brain tumours - 27 patients with neurilemmoma (8 patients), pituitary adenoma (7 patients), hemangioblastoma (6 patients), or meningioma (6 patients) undergoing surgical resection in the West China Hospital of Sichuan University. There were 15 females and 12 males aged from 28 to 70 years old. Total RNA was isolated and mRNA was measured by quantitative real-time RT-PCR. One-way analysis of variance (ANOVA) was performed using SPSS 11.0 statistical software to compare the mRNA levels of CXCR7 among four groups. Results: We found that CXCR7 mRNA was detected in all tumour samples. Quantitative results showed that the levels of CXCR7 mRNA in brain tissues from patients with neurilemmoma or meningioma were significantly higher than those with pituitary adenoma or hemangioblastoma. Conclusions: The results suggest that the CXCR7 may play a role in progression, metastasis and angiogenesis of brain tumours.
Xia Wu,Xiaoyan Chi,Yanhua Wang,Kailu Zhang,Le Kai,Qiuning He,Jinxiu Tang,Kewen Wang,Longshuo Sun,Xiuying Hao,Weihai Xie,Yihe Ge 한국식물병리학회 2019 Plant Pathology Journal Vol.35 No.4
In our previous study, pyrrolnitrin produced in Pseudomonas chlororaphis G05 plays more critical role in suppression of mycelial growth of some fungal pathogens that cause plant diseases in agriculture. Although some regulators for pyrrolnitrin biosynthesis were identified, the pyrrolnitrin regulation pathway was not fully constructed. During our screening novel regulator candidates, we obtained a white conjugant G05W02 while transposon mutagenesis was carried out between a fusion mutant G05ΔphzΔprn::lacZ and E. coli S17- 1 (pUT/mini-Tn5Kan). By cloning and sequencing of the transposon-flanking DNA fragment, we found that a vfr gene in the conjugant G05W02 was disrupted with mini-Tn5Kan. In one other previous study on P. fluorescens, however, it was reported that the deletion of the vfr caused increased production of pyrrolnitrin and other antifungal metabolites. To confirm its regulatory function, we constructed the vfr-knockout mutant G05Δvfr and G05ΔphzΔprn::lacZΔvfr. By quantifying β-galactosidase activities, we found that deletion of the vfr decreased the prn operon expression dramatically. Meanwhile, by quantifying pyrrolnitrin production in the mutant G05Δvfr, we found that deficiency of the Vfr caused decreased pyrrolnitrin production. However, production of phenazine-1-carboxylic acid was same to that in the wild-type strain G05. Taken together, Vfr is required for pyrrolnitrin but not for phenazine-1-carboxylic acid biosynthesis in P. chlororaphis G05.
Adaptive Fault-Tolerant Control Considering the Actuator Failure of Forklift Anti-Rollover System
Xia Guang,Li Tao,Tang Xiwen,Zhang Yang,Zhao Linfeng 한국자동차공학회 2023 International journal of automotive technology Vol.24 No.3
An adaptive fault-tolerant anti-rollover fuzzy system is proposed to improve the anti-rollover performance of counterbalanced forklifts. Considering the actual control input, various unpredictable actuator failure models in the system are established. Based on the three degree-of-freedom (DOF) model of a counterbalanced forklift, an anti-rollover Takagi-Sugeno (T-S) fuzzy system is established. The stability of this anti-rollover system is analyzed to ensure its stability under specific control inputs and external disturbances. When the upper limits of actuator faults and disturbances are unknown, an adaptive fault-tolerant control method is designed to update the controller parameters. The sufficient conditions for the stability of the forklift anti-rollover system in the presence of actuator faults and external disturbances are given using the Lyapunov stability theory. Simulation and real vehicle tests based on MATLAB/Simulink show that the anti-rollover system with adaptive fault-tolerant control can reduce impacts effectively and quickly after the actuator fails, thereby improving the safety and reliability of the forklift.
Xia Guang,Zhang Chenhao,Tang Xiwen,Zhang Yang,Zhao Linfeng 한국자동차공학회 2023 International journal of automotive technology Vol.24 No.5
The center of gravity of a forklift truck, a crucial parameter for vehicle stability, changes with different loads during operation. We propose an estimation algorithm for the center of gravity position suitable for a counterbalanced forklift truck. By installing sensors on the fork, we use an inclinable platform and propose a static joint center of gravity measurement method. For straight-line driving, we establish a longitudinal dynamics model and propose a nonlinear H∞ estimation algorithm. For steering conditions, we establish a roll dynamics model and propose a forgetting factor recursive least square estimation algorithm. A data fusion algorithm for the forklift truck’s center of gravity position under various working conditions is proposed. The fusion of these estimation results yields the best estimated center of gravity height. We validate the algorithm’s effectiveness using a hardware-in-the-loop simulation platform under different working conditions. The experiments demonstrate the algorithm’s fast parameter fitting, wide applicability, and accurate position control within a 5 % error range.