Perturbation observer based adaptive passive control for damping improvement of multi-terminal voltage source converter-based high voltage direct current systems

This paper proposes a Perturbation Observer-based adaptive passive control (POAPC) for damping improvement of multi-terminal voltage source converter-based high voltage direct current (VSC-MTDC) systems. The POAPC is designed for an N-terminal VSC-MTDC system, and the perturbation is defined as a lumped term including interactions between terminals, unmodelled dynamics and unknown external disturbances, which are estimated online via a perturbation observer. Then an extra system damping is injected for each terminal to improve the transient dynamics via passivation. The POAPC does not require an accurate system model and measurements of full states; only the DC voltage and active and reactive power need to be measured. Case studies are carried out on a four-terminal VSC-MTDC system under four scenarios such as active and reactive power reversal, faults at AC bus, offshore wind farm connection, and fast time-varying parameter uncertainties. Simulation results verify its effectiveness under various operating conditions, compared with that of conventional proportional-integral (PI) control and classical passive control (PC). </jats:p

Adaptive channel selection through collaborative sensing

Proper channel selection is essential to exploit the benefits of multi-channel systems by distributing conflicting transmissions across non-interfering channels? Critical to channel selection is the channel quality metric, We propose a busy time ratio (BTR) metric that captures channel contention and user traffic load under a variety of network dynamics, We also propose a distributed collaborative sensing scheme to reduce sensing overhead and energy consumptions, The proposed algorithms can be implemented using conventional 802.11 hardware with single radio interface, The proposed metric can be integrated with routing and channel selection. Experimental results show that the proposed scheme significantly outperforms the existing channel selection methods. © 2006 IEEE.published_or_final_versio

Terahertz Channel Characterization Inside the Human Skin for Nano-Scale Body-Centric Networks

This paper focuses on the development of a novel radio channel model inside the human skin at the terahertz range, which will enable the interaction among potential nano-machines operating in the inter cellular areas of the human skin. Thorough studies are performed on the attenuation of electromagnetic waves inside the human skin, while taking into account the frequency of operation, distance between the nano-machines and number of sweat ducts. A novel channel model is presented for communication of nano-machines inside the human skin and its validation is performed by varying the aforementioned parameters with a reasonable accuracy. The statistics of error prediction between simulated and modeled data are: mean (μ)= 0.6 dB and standard deviation (σ)= 0.4 dB, which indicates the high accuracy of the prediction model as compared with measurement data from simulation. In addition, the results of proposed channel model are compared with terhaertz time-domain spectroscopy based measurement of skin sample and the statistics of error prediction in this case are: μ = 2.10 dB and σ = 6.23 dB, which also validates the accuracy of proposed model. Results in this paper highlight the issues and related challenges while characterizing the communication in such a medium, thus paving the way towards novel research activities devoted to the design and the optimization of advanced applications in the healthcare domain

Synthesis of new dendritic chiral binol ligands and their applications in enantioselective lewis acid catalyzed addition of diethylzinc to aldehydes

2002-2003 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

THz Time-Domain Spectroscopy of Human Skin Tissue for In-Body Nanonetworks

Copyright: 2016. IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications standards/publications/rights/index.html for more information

Nano-Communication for Biomedical Applications: A Review on the State-of-the-Art From Physical Layers to Novel Networking Concepts

We review EM modeling of the human body, which is essential for in vivo wireless communication channel characterization; discuss EM wave propagation through human tissues; present the choice of operational frequencies based on current standards and examine their effects on communication system performance; discuss the challenges of in vivo antenna design, as the antenna is generally considered to be an integral part of the in vivo channel; review the propagation models for the in vivo wireless communication channel and discuss the main differences relative to the ex vivo channel; and address several open research problems and future research directions

Current status of urban wastewater treatment plants in China

© 2016 Elsevier Ltd. The study reported and analyzed the current state of wastewater treatment plants (WWTPs) in urban China from the perspective of treatment technologies, pollutant removals, operating load and effluent discharge standards. By the end of 2013, 3508 WWTPs have been built in 31 provinces and cities in China with a total treatment capacity of 1.48 × 108 m3/d. The uneven population distribution between China's east and west regions has resulted in notably different economic development outcomes. The technologies mostly used in WWTPs are AAO and oxidation ditch, which account for over 50% of the existing WWTPs. According to statistics, the efficiencies of COD and NH3-N removal are good in 656 WWTPs in 70 cities. The overall average COD removal is over 88% with few regional differences. The average removal efficiency of NH3-N is up to 80%. Large differences exist between the operating loads applied in different WWTPs. The average operating loading rate is approximately 83%, and 52% of WWTPs operate at loadings of <80%, treating up to 40% of the wastewater generated. The implementation of discharge standards has been low. Approximately 28% of WWTPs that achieved the Grade I-A Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918-2002) were constructed after 2010. The sludge treatment and recycling rates are only 25%, and approximately 15% of wastewater is inefficiently treated. Approximately 60% of WWTPs have capacities of 1 × 104 m3/d-5 × 104 m3/d. Relatively high energy consumption is required for small-scale processing, and the utilization rate of recycled wastewater is low. The challenges of WWTPs are discussed with the aim of developing rational criteria and appropriate technologies for water recycling. Suggestions regarding potential technical and administrative measures are provided