Enhanced remote astronomical archive system based on the file-level Unlimited Sliding-Window technique

Abstract Data archiving is one of the most critical issues for modern astronomical observations. With the development of a new generation of radio telescopes, the transfer and archiving of massive remote data have become urgent problems to be solved. Herein, we present a practical and robust file-level flow-control approach, called the Unlimited Sliding-Window (USW), by referring to the classic flow-control method in the TCP protocol. Based on the USW and the Next Generation Archive System (NGAS) developed for the Murchison Widefield Array telescope, we further implemented an enhanced archive system (ENGAS) using ZeroMQ middleware. The ENGAS substantially improves the transfer performance and ensures the integrity of transferred files. In the tests, the ENGAS is approximately three to twelve times faster than the NGAS and can fully utilize the bandwidth of network links. Thus, for archiving radio observation data, the ENGAS reduces the communication time, improves the bandwidth utilization, and solves the remote synchronous archiving of data from observatories such as Mingantu spectral radioheliograph. It also provides a better reference for the future construction of the Square Kilometer Array (SKA) Science Regional Center.

Download Full-text

ICMA: AN EFFICIENT INTEGRATED CONGESTION CONTROL APPROACH

Recent Patents on Engineering ◽

10.2174/1872212114666191231150916 ◽

2019 ◽

Vol 14 ◽

Author(s):

Tayyab Khan ◽

Karan Singh ◽

Kamlesh C. Purohit

Keyword(s):

Congestion Control ◽

Packet Loss ◽

Control Method ◽

Multicast Communication ◽

Bandwidth Utilization ◽

File Transfer ◽

Control Approach ◽

Communication Technique ◽

Control Scheme ◽

Multiparty Video Conferencing

Background: With the growing popularity of various group communication applications such as file transfer, multimedia events, distance learning, email distribution, multiparty video conferencing and teleconferencing, multicasting seems to be a useful tool for efficient multipoint data distribution. An efficient communication technique depends on the various parameters like processing speed, buffer storage, and amount of data flow between the nodes. If data exceeds beyond the capacity of a link or node, then it introduces congestion in the network. A series of multicast congestion control algorithms have been developed, but due to the heterogeneous network environment, these approaches do not respond nor reduce congestion quickly whenever network behavior changes. Objective: Multicasting is a robust and efficient one-to-many (1: M) group transmission (communication) technique to reduced communication cost, bandwidth consumption, processing time and delays with similar reliability (dependability) as of regular unicast. This patent presents a novel and comprehensive congestion control method known as integrated multicast congestion control approach (ICMA) to reduce packet loss. Methods: The proposed mechanism is based on leave-join and flow control mechanism along with proportional integrated and derivate (PID) controller to reduce packet loss, depending on the congestion status. In the proposed approach, Proportional integrated and derivate controller computes expected incoming rate at each router and feedback this rate to upstream routers of the multicast network to stabilize their local buffer occupancy. Results: Simulation results on NS-2 exhibit the immense performance of the proposed approach in terms of delay, throughput, bandwidth utilization, and packet loss than other existing methods. Conclusion: The proposed congestion control scheme provides better bandwidth utilization and throughput than other existing approaches. Moreover, we have discussed existing congestion control schemes with their research gaps. In the future, we are planning to explore the fairness and quality of service issue in multicast communication.

Download Full-text

A Critical Review of Supersonic Flow Control for High-Speed Applications

Applied Sciences ◽

10.3390/app11156899 ◽

2021 ◽

Vol 11 (15) ◽

pp. 6899

Author(s):

Abdul Aabid ◽

Sher Afghan Khan ◽

Muneer Baig

Keyword(s):

Supersonic Flow ◽

Flow Control ◽

Active Control ◽

Critical Review ◽

High Speed ◽

Passive Control ◽

Control Method ◽

Sudden Expansion ◽

Control Approach ◽

Cost Efficient

In high-speed fluid dynamics, base pressure controls find many engineering applications, such as in the automobile and defense industries. Several studies have been reported on flow control with sudden expansion duct. Passive control was found to be more beneficial in the last four decades and is used in devices such as cavities, ribs, aerospikes, etc., but these need additional control mechanics and objects to control the flow. Therefore, in the last two decades, the active control method has been used via a microjet controller at the base region of the suddenly expanded duct of the convergent–divergent (CD) nozzle to control the flow, which was found to be a cost-efficient and energy-saving method. Hence, in this paper, a systemic literature review is conducted to investigate the research gap by reviewing the exhaustive work on the active control of high-speed aerodynamic flows from the nozzle as the major focus. Additionally, a basic idea about the nozzle and its configuration is discussed, and the passive control method for the control of flow, jet and noise are represented in order to investigate the existing contributions in supersonic speed applications. A critical review of the last two decades considering the challenges and limitations in this field is expressed. As a contribution, some major and minor gaps are introduced, and we plot the research trends in this field. As a result, this review can serve as guidance and an opportunity for scholars who want to use an active control approach via microjets for supersonic flow problems.

Download Full-text

Real-Time Validation of Power Flow Control Method for Enhanced Operation of Microgrids

Energies ◽

10.3390/en13225959 ◽

2020 ◽

Vol 13 (22) ◽

pp. 5959

Author(s):

Hossein Abedini ◽

Tommaso Caldognetto ◽

Paolo Mattavelli ◽

Paolo Tenti

Keyword(s):

Flow Control ◽

Real Time ◽

Data Exchange ◽

Power Flow ◽

Control Method ◽

Low Voltage ◽

Power Flow Control ◽

Real Time Simulation ◽

Control Approach ◽

Time Simulation

This paper describes a control methodology for electronic power converters distributed in low-voltage microgrids and its implementation criteria in general microgrid structures. In addition, a real-time simulation setup is devised, implemented, and discussed to validate the control operation in a benchmark network. Considering these key aspects, it is shown that operational constraints regarding the power delivered by sources, flowing through network branches, and exchanged at the point of connection with the main grid can generally be fulfilled by the presented control approach. The control is performed considering a cost function aiming at optimizing various operation indexes, including distribution losses, current stresses on feeders, voltage deviations. The control system allows an enhanced operation of the microgrid, specifically, it allows dynamic and accurate power flow control enabling the provision of ancillary services to the upstream grid, like the demand–response, by exploiting the available infrastructure and the energy resources. Then, the validation of the approach is reported by using a real-time simulation setup with accurate models of the power electronic converters and related local controllers, of the grid infrastructure, of the power flow controller, and of the communication network used for data exchange. It is also shown that the implemented platform allows to fully reproduce, analyze, and finally validate all the relevant steady-state and dynamic behaviors related in the considered scenario.

Download Full-text

Power-Flow Control Method for Wireless In-Wheel Motor with Supercapacitor

IEEJ Transactions on Industry Applications ◽

10.1541/ieejias.138.219 ◽

2018 ◽

Vol 138 (3) ◽

pp. 219-226

Author(s):

Takuma Takeuchi ◽

Takehiro Imura ◽

Daisuke Gunji ◽

Hiroshi Fujimoto ◽

Yoichi Hori

Keyword(s):

Flow Control ◽

Power Flow ◽

Control Method ◽

Power Flow Control

Download Full-text

Improved Feeder Flow Control Method for a Virtual Power Plant With Various Resources to Reduce Communication Dependency

IEEE Access ◽

10.1109/access.2020.3035867 ◽

2020 ◽

Vol 8 ◽

pp. 206820-206834

Author(s):

Jae-Won Chang ◽

Hee Seung Moon ◽

Seung-Il Moon ◽

Yong Tae Yoon ◽

Mark B. Glick ◽

...

Keyword(s):

Power Plant ◽

Flow Control ◽

Control Method ◽

Virtual Power ◽

Virtual Power Plant

Download Full-text

A Novel Adaptive Control Approach Based on Available Headroom of the VSC-HVDC for Enhancement of the AC Voltage Stability

Energies ◽

10.3390/en14113222 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3222

Author(s):

Duc Nguyen Huu

Keyword(s):

Adaptive Control ◽

Voltage Stability ◽

Reactive Power ◽

Control Method ◽

Offshore Wind ◽

Voltage Source ◽

Long Distance ◽

Control Approach ◽

Hvdc System ◽

Voltage Support

Increasing offshore wind farms are rapidly installed and planned. However, this will pose a bottle neck challenge for long-distance transmission as well as inherent variation of their generating power outputs to the existing AC grid. VSC-HVDC links could be an effective and flexible method for this issue. With the growing use of voltage source converter high-voltage direct current (VSC-HVDC) technology, the hybrid VSC-HVDC and AC system will be a next-generation transmission network. This paper analyzes the contribution of the multi VSC-HVDC system on the AC voltage stability of the hybrid system. A key contribution of this research is proposing a novel adaptive control approach of the VSC-HVDC as a so-called dynamic reactive power booster to enhance the voltage stability of the AC system. The core idea is that the novel control system is automatically providing a reactive current based on dynamic frequency of the AC system to maximal AC voltage support. Based on the analysis, an adaptive control method applied to the multi VSC-HVDC system is proposed to realize maximum capacity of VSC for reactive power according to the change of the system frequency during severe faults of the AC grid. A representative hybrid AC-DC network based on Germany is developed. Detailed modeling of the hybrid AC-DC network and its proposed control is derived in PSCAD software. PSCAD simulation results and analysis verify the effective performance of this novel adaptive control of VSC-HVDC for voltage support. Thanks to this control scheme, the hybrid AC-DC network can avoid circumstances that lead to voltage instability.

Download Full-text

Lifetime and reliability improvements in modular multilevel converters using controlled circulating current

Journal of Power Electronics ◽

10.1007/s43236-021-00297-7 ◽

2021 ◽

Author(s):

Nasiru B. Kadandani ◽

Mohamed Dahidah ◽

Salaheddine Ethni ◽

Musbahu Muhammad

Keyword(s):

Control Method ◽

Semiconductor Devices ◽

Junction Temperature ◽

Multilevel Converters ◽

Control Approach ◽

Circulating Current ◽

Inherent Feature ◽

Modular Multilevel Converters ◽

Current Loading ◽

Laboratory Prototype

AbstractCirculating current has been an inherent feature of modular multilevel converters (MMC), which results in second-order harmonics on the arms currents. If not properly controlled, the circulating current can affect the lifetime and reliability of a converter by increasing the current loading, loss distribution, and junction temperature of its semiconductor devices. This paper proposes controlled circulating current injection as a means of improving the lifetime and reliability of an MMC. The proposed method involves modifying the reference modulating signals of the converter arms to include the controlled differential voltage as an offset. The junction temperature of the semiconductor devices obtained from an electro-thermal simulation is processed to deduce the lifetime and reliability of the converter. The obtained results are benchmarked against a case where the control method is not incorporated. The incorporation of the proposed control method results in a 68.25% increase in the expected lifetime of the converter and a 3.06% increase on its reliability index. Experimental results of a scaled down laboratory prototype validate the effectiveness of the proposed control approach.

Download Full-text

Trajectory following control of lower limb exoskeleton robot based on Udwadia–Kalaba theory

Journal of Vibration and Control ◽

10.1177/10775463211031701 ◽

2021 ◽

pp. 107754632110317

Author(s):

Jin Tian ◽

Liang Yuan ◽

Wendong Xiao ◽

Teng Ran ◽

Li He

Keyword(s):

Lower Limb ◽

Control Method ◽

Uniform Boundedness ◽

Adaptive Robust Control ◽

Structural Vibration ◽

Control Approach ◽

Lower Limb Exoskeleton ◽

Exoskeleton Robot ◽

Constraint Problem ◽

Trajectory Following

The main objective of this article is to solve the trajectory following problem for lower limb exoskeleton robot by using a novel adaptive robust control method. The uncertainties are considered in lower limb exoskeleton robot system which include initial condition offset, joint resistance, structural vibration, and environmental interferences. They are time-varying and have unknown boundaries. We express the trajectory following problem as a servo constraint problem. In contrast to conventional control methods, Udwadia–Kalaba theory does not make any linearization or approximations. Udwadia–Kalaba theory is adopted to derive the closed-form constrained equation of motion and design the proposed control. We also put forward an adaptive law as a performance index whose type is leakage. The proposed control approach ensures the uniform boundedness and uniform ultimate boundedness of the lower limb exoskeleton robot which are demonstrated via the Lyapunov method. Finally, simulation results have shown the tracking effect of the approach presented in this article.

Download Full-text