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Suitable triggering algorithms for detecting strong ground motions using MEMS accelerometers

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Earthquake Engineering and Engineering Vibration 2015年第1期14卷 27-35页

作者： ravi sankar Jakka Siddharth Garg Department of Earthquake Engineering Indian Institute of Technology

With the recent development of digital Micro Electro Mechanical System （MEMS） sensors, the cost of monitoring and detecting seismic events in real time can be greatly reduced. Ability of MEMS accelerograph to record a seismic event depends upon the efficiency of triggering algorithm, apart from the sensor＇s sensitivity. There are several classic triggering algorithms developed to detect seismic events, ranging from basic amplitude threshold to more sophisticated pattern recognition. Algorithms based on STA/LTA are reported to be computationally efficient for real time monitoring. In this paper, we analyzed several STA/LTA algorithms to check their efficiency and suitability using data obtained from the Quake Catcher Network （network of MEMS accelerometer stations）. We found that most of the STA/LTA algorithms are suitable for use with MEMS accelerometer data to accurately detect seismic events. However, the efficiency of any particular algorithm is found to be dependent on the parameter set used （i.e., window width of STA, LTA and threshold level）.

关键词： strong ground motion triggering algorithms seismic event detection MEMS accelerometers STA/LTA based algorithms

A Review on Surface Stress-Based Miniaturized Piezoresistive SU-8 Polymeric Cantilever Sensors

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Nano-Micro Letters 2018年第2期10卷 198-238页

作者： Ribu Mathew A.ravi sankar School of Electronics Engineering (SENSE) Vellore Institute of Technology (VIT) Chennai

In the last decade, microelectromechanical systems(MEMS) SU-8 polymeric cantilevers with piezoresistive readout combined with the advances in molecular recognition techniques have found versatile applications,especially in the field of chemical and biological *** to conventional solid-state semiconductor-based piezoresistive cantilever sensors, SU-8 polymeric cantilevers have advantages in terms of better sensitivity along with reduced material and fabrication cost. In recent times,numerous researchers have investigated their potential as a sensing platform due to high performance-to-cost ratio of SU-8 polymer-based cantilever sensors. In this article, we critically review the design, fabrication, and performance aspects of surface stress-based piezoresistive SU-8 polymeric cantilever sensors. The evolution of surface stress-based piezoresistive cantilever sensors from solid-state semiconductor materials to polymers, especially SU-8 polymer, is discussed in detail. Theoretical principles of surface stress generation and their application in cantilever sensing technology are also devised. Variants of SU-8 polymeric cantilevers with different composition of materials in cantilever stacks are explained. Furthermore, the interdependence of the material selection, geometrical design parameters, and fabrication process of piezoresistive SU-8 polymeric cantilever sensors and their cumulative impact on the sensor response are also explained in *** addition to the design-, fabrication-, and performancerelated factors, this article also describes various challenges in engineering SU-8 polymeric cantilevers as a universal sensing platform such as temperature and moisture vulnerability. This review article would serve as a guideline for researchers to understand specifics and functionality of surface stress-based piezoresistive SU-8 cantilever sensors.

关键词： SU-8 polymer Surface stress Biological sensor Cantilever Chemical sensor Piezoresistor Immobilization

QoS aware routing and wavelength allocation in optical burst switching networks using differential evolution optimization

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Digital Communications and Networks 2018年第1期4卷 3-12页

作者： ravi sankar Barpanda Ashok Kumar Turuk Bibhudatta Sahoo Department of Computer Science & Engineering National Instiute of Technology Rourkela India 769008

The issue of burst losses imposes a constraint on the development of Optical Burst Switching （OBS） networks. Heavy burst losses strongly affect the Quality of Service （QoS） intended by end users. This article presents a QoS aware Routing and Wavelength Allocation （RWA） technique for burst switching in OBS networks. The RWA problem is modeled as a bi-objective Integer Linear Programming （ILP） problem, where objective functions are based on minimizing the number of wavelengths used and the number of hops traversed to fulfill the burst transmission requests for a given set of node pairs. The ILP model is solved using a novel approach based on a Differential Evolution （DE） algorithm. Analytical results show that the DE algorithm provides a better performance compared to shortest path routing, which is a widely accepted routing strategy for OBS networks.

关键词： Burst loss Optical burst switching Quality of service Routing and wavelength assignmentInteger linear programmingDifferential evolution

Characterization of municipal solid waste based on seasonal variations,source and socio-economic aspects

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Waste Disposal and Sustainable Energy 2021年第4期3卷 275-288页

作者： Venkata ravi sankar Cheela Sudha Goel Michele John Brajesh Dubey Environmental Engineering and Management Department of Civil EngineeringIndian Institute of Technology KharagpurKharagpurWest Bengal 721302India Sustainable Engineering Group Curtin UniversityPerthWA 6102Australia

Municipal solid waste(MSW)generation and characterization are the basic inputs for waste handling and treatment systems *** present research,we performed waste characterization investigations in Visakhapatnam(India),using a waste characterization methodology by integrating two standard sampling and characterization *** characterization methodology was designed by combining seasonal variations,source,and socio-economic ***-based sampling was performed at household(s),dumpster(s),transfer station,and ***-economic-based sampling was performed based on the zone classification of the *** sampling campaigns were conducted to identify the waste composition based on seasonal *** aimed to perform stratified characterization of waste and assess chemical characteristics of the mixed waste fractions to evaluate waste-to-energy *** indicate that the amount of MSW generated in the city is 1250±100 tons/day,with a generation rate of 0.65 kg/capita/*** on source stratification,organic matter(45.5%±6.5%)is a major component followed by inert *** paper,plastic,and textile components amount to 25%of overall *** seasonal studies,organic matter was higher in pre-monsoon(42%)compared to winter(39%).The moisture content of MSW varied between 30%and 35%and volatile solids between 39%and 43%.The calorific value was determined to be between 5680-7110 kJ/*** the limitations and potential errors associated with sampling and waste *** and thermal conversion treatment alternatives for processing,treatment,and handling were *** findings of this research would assist regulatory bodies and city councils to formulate policy directives on waste sampling,characterization,segregation,education,and awareness campaigns.

关键词： Municipal solid waste Waste characterization Source segregation Socio-economic Seasonal variation Waste-to-energy

Double-sided friction stir welding of Nitronic-40 stainless steel for application in tokamak devices

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Journal of Materials Science & Technology 2023年第28期159卷 170-183页

作者： Supreeth Gaddam ravi sankar Haridas Deepthi Tammana Charlie Sanabria Christopher J.Lammi Diana Berman Rajiv S.Mishra Center for Friction Stir Processing Department of Materials Science and EngineeringUniversity of North TexasDentonTX76207USA Advanced Materials and Manufacturing Processes Institute University of North TexasDentonTX76207USA Department of Mechanical Engineering University of North TexasDentonTX76207USA Commonwealth Fusion Systems CambridgeMAUSA

Nitrogen containing austenitic stainless steels(N-ASS)are widely utilized to fabricate various structural components in tokamak type fusion reactors owing to their suitable mechanical and functional *** components are exposed to a range of temperatures(4-500 K)and interact closely with the magnetic fields that are used to control and contain the plasma within the tokamak ***-40(N40)or XM-11 stainless steel is one such N-ASS used for fabricating structural components in the mag-netic and vacuum vessel systems in tokamak *** of most of the larger components in the magnetic and vacuum vessel systems typically involves some type of fusion-based welding *** study presents a double-sided friction stir welding(FSW)approach as an alternative to fusion welding processes to join 12 mm thick N40 plates to obtain joints with a low fraction ofδferrite(a detrimen-tal ferromagnetic phase),high joint efficiency,no sensitization and loss of hardness in the heat affected zone,and minimal nitrogen desorption from the weld *** double-sided FSW approach yielded superior weldments when compared to similar joints accomplished by fusion welding for application in tokamak devices.

关键词： Friction stir welding Nitronic-40 stainless steel XM-11 stainless steel Magnetic and vacuum vessel systems Tokamak devices

Formulation and evaluation of novel aspirin nanoparticles loaded suppositories

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Journal of Chinese Pharmaceutical Sciences 2013年第3期22卷 259-267页

作者： ravi sankar V. Dhachinamoorthi D. Chandra Shekar K.B. Department of Pharmaceutics C.E.S College of Pharmacy Departments of Pharmaceutics Q.I.S College of Pharmacy Department of Chemistry J.N.T.A University

The main objective of the present work is to design aspirin nanoparticles loaded suppositories which will reduce the side effects caused by aspirin suppositories. Aspirin nanoparticles were prepared initially based on ionic-gelation mechanism and lyophilized. The prepared nanoparticles were evaluated, and the results confirmed that Fa9 formulation was the best with greater drug entrapment efficiency. Aspirin suppositories were prepared in order to investigate the best base composition. The prepared suppositories were evaluated and FS1, FS3, FS4, FSS, FS1 l, and FS12 were proved to be the best base compositions based on dissolution performed. The lyophilized aspirin nanoparticles of Fa9 were used to prepare aspirin nanoparticles loaded suppositories. The in vitro results revealed that Fasl 1 was the best formulation.

关键词： Suppositories Ionic-gelation method Rectal carcinoma Aspirin Lyophilization

Multi-Criteria Fuzzy-Based Decision Making Algorithm to Optimize the VHO Performance in Hetnets

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Computers, Materials & Continua 2022年第1期70卷 323-341页

作者： A.Prithiviraj A.Maheswari D.Balamurugan Vinayakumar ravi Moez Krichen Roobaea Alroobaea Saeed Rubaiee sankar Sennan Department of CSE Sona College of TechnologySalem636005India Department of CSE Dr.M.G.R.Educational and Research InstituteChennai600095India Center for Artificial Intelligence PrinceMohammad Bin Fahd UniversityKhobarSaudi Arabia Faculty of CSIT Al-Baha UniversitySaudi Arabia ReDCAD laboratory University of SfaxTunisia Department of Computer Science College of Computers and Information TechnologyTaif UniversityTaif21944Saudi Arabia Department of Industrial and Systems Engineering College of EngineeringUniversity of JeddahJaddahSaudi Arabia

Despite the seemingly exponential growth of mobile and wireless communication,this same technology aims to offer uninterrupted access to different wireless systems like Radio Communication,Bluetooth,and Wi-Fi to achieve better network connection which in turn gives the best quality of service(QoS).Many analysts have established many handover decision systems(HDS)to enable assured continuous mobility between various radio access *** is one of themost significant problems considered in wireless communication *** application needs a distinct QoS,so the network choice may shift *** achieve this objective and to choose the finest networks,it is important to select a best decision making algorithm that chooses the most effective network for every application that the user requires,dependent on QoS ***,the main goal of the proposed system is to provide an enhanced vertical handover(VHO)decision making programby using aMulti-CriteriaFuzzy-Based algorithm to choose the best *** Multi-Criteria algorithms and a Fuzzy-Based algorithm is implemented successfully for optimal network selection and also to minimize the probability of false ***,a double packet buffer is utilized to decrease the packet loss by 1.5%and to reduce the number of handovers up to 50%compared to the existing *** addition,the network setup has an optimized mobilitymanagement system to supervise the movement of the mobile nodes.

关键词： Vertical handover mobility management handover decision systems multi-criteria fuzzy logic QoS false handover

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一种无时间标记的包调度策略

通信学报 2002年第7期23卷 26-32页

作者：冯穗力叶梧 sankar ravi 柯峰华南理工大学电子与通信工程系广东广州510640

本文提出一种多队列的包调度算法,该方法在调度的公平性、延时和所需的缓冲空间等性能方面与PGPS,PRPS等调度算法有相同的性能,同时无需对各个到达的数据包记上时间标记,使调度操作更为简单有效。

关键词：无时间标记包调度调度算法 PRBS 计算机网络服务质量 QOS

Antibiotic activity of different solvent extracts of the marine gastropod Thais bufo against Staphylococcus aureus and Streptococcus pyogenes

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Journal of Coastal Life Medicine 2017年第1期5卷 7-12页

作者： ravi Raja Arularasan Sabapathi Vishwanathan sankar Centre of Advanced Study in Marine Biology Faculty of Marine SciencesAnnamalai UniversityChidambaramIndia

Objective:To evaluate the antimicrobial activity of different solvent extracts of the species Thais bufo against theStreptococcus pyogenes andStaphylococcus aureus. Methods:Different types of solvents were used such as acetone, benzene, butanol, chloroform, ethanol, ethyl acetate, hexane, methanol, toluene and distilled water for extraction, based on the polarity basis for the purpose of minimizing the process and error in identification and characterization of the active compound. Results: Regarding the percentage of yield, aqueous extract yielded the highest percentage, following that methanolic extract and other extracts in the order of ethanol, hexane, chloroform, ethyl acetate, butanol, benzene, acetone and toluene. In the perception of antibiotic activity, ethyl acetate and methanol showed better activity against both the species. Through the results, it is clear that the methanolic extract have mild antimicrobial activity. The antimicrobial activity in the form of zone of inhibition was below the value of 7.5 mm. Further, the qualitative analysis was carried out only for the methanolic extract, due to its overall activity. Through the qualitative analysis by thin layer chromatography it happened to know that 3 bands were formed and theirRf values were 0.07, 0.17 and 0.44 respectively. Conclusions: The results showed that the solvent extracts of the speciesThais bufohave no potential antibiotic activity, hence it cannot be considered for the further research in the field of drug discovery.

关键词： Rheumatic heart disease Drug discovery Rheumatic fever Permitted daily exposure