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STEP-based Feature Recognition System for B-spline Surface Features

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International Journal of Automation and computing 2018年第4期15卷 500-512页

作者： Bitla Venu Venkateswara Rao Komma Deepanshu srivastava Department of Mechanical Engineering Motilal Nehru National Institute of Technology

The geometrical and topological information of 3D computer aided design （CAD） models should be represented as a neut- ral format file to exchange the data between different CAD systems. Exchange of 3D CAD model data implies that the companies must exchange complete information about their products, all the way from design, manufacturing to inspection and shipping. This informa- tion should be available to each relevant partner over the entire life cycle of the product. This led to the development of an international standard organization （ISO） neutral format file named as standard for the exchange of product model data （STEP）. It has been ob- served from the literature, the feature recognition systems developed were identified as planar, cylindrical, conical and to some extent spherical and toroidal surfaces. The advanced surface features such as B-spline and its subtypes are not identified. Therefore, in this work, a STEP-based feature recognition system is developed to recognize t--spline surface features and its sub-types from the 3D CAD model represented in AP203 neutral file format. The developed feature recognition system is implemented in Java programming language and the product model data represented in STEP AP203 format is interpreted through Java standard data access interface （JSDAI）. The developed system could recognize B-spline surface features such as B-Spline surface with knots, quasi uniform surface, uniform surface, rational surface and Bezier surface. The application of extracted B-spline surface features information is discussed with reference to the toolpath generation for STEP-NC （STEP AP238）.

关键词： Feature recognition 3D computer aided design(CAD)model geometrical information standard for the exchange ofproduct model data(STEP)AP203 Java standard data access interface(JSDAI).

Luminescence Dating and Bracketing Time of the Youngest Toba Tuff Deposits in the Quaternary Sediments of Purna Alluvial Basin,Central India

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Journal of Earth Science 2022年第4期33卷 1007-1016页

作者： Singh Ajab K.srivastava Ashok Chauhan Naveen Department of Geology Faculty of ScienceUniversity of MalayaKuala Lumpur 50603Malaysia Department of Geology SGB Amravati UniversityAmravati 444602India Physical Research Laboratory Ahmedabad 380009India

Light gray to yellowish brown youngest Toba tuff(YTT)ash,preserved in the Quaternary sediments of India,have been used as a tool to know depositional and bracketing time period of the same in the sediments through applications of luminescence dating to interpret age connotation of various geological ***-and post-tephra sediments of YTT ash beds from Hudki and Sukali areas of Purna alluvial basin,Central India have been optically dated to interpret the depositional age and bracketing time of the tephra within sedimentary *** sediments are yellowish brown,thinly bedded,laminated,silty clay and host laterally extend discontinued beds of 0.15–0.20 m *** ash is light gray,fine grained and powdery in nature,massive to structureless and lacks any sign of retransportation and redeposition,hence,considered as primary in *** four sediment samples,one each from pre-and post-tephra lithounits of both the localities have been dated through optically stimulated luminescence technique(OSL)equipped with single aliquot regenerative(SAR)procedure on the feldspar *** shows pre-and post-tephra ages of 57±5 and 70±4 ka respectively for Hudki and 66±5 and 67±4 ka for Sukali *** depositional ages suggest that the ash was bracketed within sediments thousands years after YTT *** is correlatable with the previously reported depositional and absolute ages for the YTT ash from the localities of Ghoghara and Khuntheli,Son Valley;Tejpur,Madhumati River Basin and Jwalapuram,Jurreru *** ages also provide an idea about the period of existence of biological communities represented by the remains of faunal and vegetational activities before and during settlement of the YTT ash in the basin area.

关键词： youngest Toba tuff Tephra optically stimulated luminescence Quaternary sediments depositional age

Efficient Aggregation Algorithms on Very LargeCompressed Data Warehouses

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Journal of Computer Science & Technology 2000年第3期15卷 213-229页

作者：李建中李英姝 Jaideep srivastava DepartmentofComputerScienceandEngineering HarbinInstituteofTechnologyHatrbin150001P.R.China

Multidimensional aggregation is a dominant operation on data ware-houses for on-line analytical processing (OLAP). Many efficient algorithms to compute multidimensional aggregation on relational database based data warehouseshave been developed. However, to our knowledge, there is nothing to date in theliterature about aggregation algorithms on multidimensional data warehouses thatstore datasets in multidimensional arrays rather than in tables. This paper presentsa set of multidimensional aggregation algorithms on very large and compressed mul-tidimensional data warehouses. These algorithms operate directly on compresseddatasets in multidimensional data warehouses without the need to first decompressthem. They are applicable to a variety of data compression methods. The algorithmshave differefit performance behavior as a function of dataset parameters, sizes of out-puts and main memory availability. The algorithms are described and analyzed withrespect to the I/O and CPU costs. A decision procedure to select the most efficientalgorithm, given an aggregation request, is also proposed. The analytical and ex-perimental results show that the algorithms are more efficient than the traditionalaggregation algorithms.

关键词： OLAP aggregation data warehouse

UNIFORM APPROXIMATION OF ENTIRE FUNCTIONS OF SLOW GROWTH ON COMPACT SETS

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Acta Mathematica Scientia 2012年第6期32卷 2401-2410页

作者： G.S.srivastava S.Kuma Department of Mathematics Indian Institute of Technology RoorkeeRoorkee-247667India Department of Mathematics Central University of Himachal PradeshDharamshala-176215India

In the present paper, we study the polynomial approximation of entire functions of several complex variables. The characterizations of generalized order and generalized type of entire functions of slow growth are obta... 详细信息

关键词： entire function generalized order generalized type approximation errors interpolation errors

Linking temporal records

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Frontiers of Computer Science 2012年第3期6卷 293-312页

作者： Pei LI Xin Luna DONG Andrea MAURINO Divesh srivastava Department of Informatics Systems and Communication University of Milan-Bicocca Milan 20126 Italy Data Management Department AT&T Labs-Research Florham Park NJ 07932 USA

Many data sets contain temporal records which span a long period of time; each record is associated with a time stamp and describes some aspects of a real-world en- tity at a particular time （e.g., author information in DBLP）. In such cases, we often wish to identify records that describe the same entity over time and so be able to perform interest- ing longitudinal data analysis. However, existing record link- age techniques ignore temporal information and fall short for temporal data. This article studies linking temporal records. First, we ap- ply time decay to capture the effect of elapsed time on entity value evolution. Second, instead of comparing each pair of records locally, we propose clustering methods that consider the time order of the records and make global decisions. Ex- perimental results show that our algorithms significantly out- perform traditional linkage methods on various temporal data sets.

关键词： temporal data record linkage data integration

Upper ocean high resolution regional modeling of the Arabian Sea and Bay of Bengal

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Acta Oceanologica Sinica 2019年第5期38卷 32-50页

作者： Dwivedi Suneet Mishra Alok Kumar srivastava Atul K Banerjee Centre of Atmospheric and Ocean Studies and M N Saha Centre of Space Studies University of Allahabad

In this paper, effort is made to demonstrate the quality of high-resolution regional ocean circulation model in realistically simulating the circulation and variability properties of the northern Indian Ocean(10°S–25°N,45°–100°E) covering the Arabian Sea(AS) and Bay of Bengal(BoB). The model run using the open boundary conditions is carried out at 10 km horizontal resolution and highest vertical resolution of 2 m in the upper *** surface and sub-surface structure of hydrographic variables(temperature and salinity) and currents is compared against the observations during 1998–2014(17 years). In particular, the seasonal variability of the sea surface temperature, sea surface salinity, and surface currents over the model domain is studied. The highresolution model's ability in correct estimation of the spatio-temporal mixed layer depth(MLD) variability of the AS and BoB is also shown. The lowest MLD values are observed during spring(March-April-May) and highest during winter(December-January-February) seasons. The maximum MLD in the AS(BoB) during December to February reaches 150 m (67 m). On the other hand, the minimum MLD in these regions during March-April-May becomes as low as 11–12 m. The influence of wind stress, net heat flux and freshwater flux on the seasonal variability of the MLD is discussed. The physical processes controlling the seasonal cycle of sea surface temperature are investigated by carrying out mixed layer heat budget analysis. It is found that air-sea fluxes play a dominant role in the seasonal evolution of sea surface temperature of the northern Indian Ocean and the contribution of horizontal advection, vertical entrainment and diffusion processes is small. The upper ocean zonal and meridional volume transport across different sections in the AS and BoB is also computed. The seasonal variability of the transports is studied in the context of monsoonal currents.

关键词： Indian Ocean modeling Arabian Sea and Bay of Bengal mixed layer depth transport

Security Attacks in Named Data Networking: A Review and Research Directions

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Journal of Computer Science & Technology 2019年第6期34卷 1319-1350页

作者： Naveen Kumar Ashutosh Kumar Singh Abdul Aleem Shashank srivastava Department of Computer Science and Engineering Motilal Nehru National Institute of Technology Allahabad Prayagraj 211004India

Contents such as audios,videos,and images,contribute most of the Internet traffic in the current *** content sharing is a tedious *** existing security solutions do not secure data but secure the communicating *** data networking(NDN)secures the data by enforcing the data publisher to sign the *** user can verify the data by using the public key of the *** is resilient to most of the probable security attacks in the TCP/IP model due to its new ***,new types of attacks are possible in *** article surveys the most significant security attacks in NDN such as interest flooding attacks,cache privacy attacks,cache pollution attacks,and content poisoning *** attack is classified according to their behavior and discussed for their detection techniques,countermeasures,and the affected *** article is an attempt to help new researchers in this area to gather the domain knowledge of *** article also provides open research issues that could be addressed by researchers.

关键词： named data networking(NDN) interest flooding attack cache privacy attack cache pollution attack content poisoning attack

Legumes from the Paleocene sediments of India and their ecological significance

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Plant Diversity 2023年第2期45卷 199-210页

作者： Harshita Bhatia Gaurav srivastava R.C.Mehrotra Birbal Sahni Institute of Palaeosciences 53 University RoadLucknow 226007India Academy of Scientific and Innovative Research(AcSIR) Ghaziabad 201002India

During the early Paleogene,greenhouse gases created warm global *** warm climates redistributed the habitat of marine and terrestrial biota *** the ecology of biotas under extremely warm climates is important to decipher their behavior in future climate *** we report two new legume fossils(Leguminocarpum meghalayensis Bhatia,srivastava et Mehrotra ***.,and Parvileguminophyllum damalgiriensis Bhatia,srivastava et Mehrotra ***.) from the late Paleocene sediments of Tura Formation of Meghalaya,northeast ***,the Paleocene legume fossil records indicate that legumes most likely immigrated to India from Africa via the Ladakh-Kohistan Arc during the early ***,previously reconstructed climate data from the Tura Formation indicate that legumes were well adapted to a warm seasonal climate with monsoon rains.

关键词： Fabaceae Global warming Fruits Damalgiri Tura Rhynchosia

Microstructure transformations and improving wear resistance of austenitic stainless steel additively fabricated by arc-based DED process

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