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21.
Praveen Seshadri 《The VLDB Journal The International Journal on Very Large Data Bases》1998,7(3):130-140
The explosion in complex multimedia content makes it crucial for database systems to support such data efficiently. This
paper argues that the “blackbox” ADTs used in current object-relational systems inhibit their performance, thereby limiting
their use in emerging applications. Instead, the next generation of object-relational database systems should be based on
enhanced abstract data type (E-ADT) technology. An (E-ADT) can expose the semantics of its methods to the database system, thereby permitting advanced query optimizations. Fundamental architectural changes
are required to build a database system with E-ADTs; the added functionality should not compromise the modularity of data
types and the extensibility of the type system. The implementation issues have been explored through the development of E-ADTs
in Predator. Initial performance results demonstrate an order of magnitude in performance improvements.
Received January 1, 1998 / Accepted May 27, 1998 相似文献
22.
Deep packet inspection using parallel bloom filters 总被引:2,自引:0,他引:2
There is a class of packet processing applications that inspect packets deeper than the protocol headers to analyze content. For instance, network security applications must drop packets containing certain malicious Internet worms or computer viruses carried in a packet payload. Content forwarding applications look at the hypertext transport protocol headers and distribute the requests among the servers for load balancing. Packet inspection applications, when deployed at router ports, must operate at wire speeds. With networking speeds doubling every year, it is becoming increasingly difficult for software-based packet monitors to keep up with the line rates. We describe a hardware-based technique using Bloom filters, which can detect strings in streaming data without degrading network throughput. A Bloom filter is a data structure that stores a set of signatures compactly by computing multiple hash functions on each member of the set. This technique queries a database of strings to check for the membership of a particular string. The answer to this query can be false positive but never a false negative. An important property of this data structure is that the computation time involved in performing the query is independent of the number of strings in the database provided the memory used by the data structure scales linearly with the number of strings stored in it. Furthermore, the amount of storage required by the Bloom filter for each string is independent of its length. 相似文献
23.
Kumar DD Mitra S Senthil K Sharma DK Rajan RN Sharma A Nagesh KV Chakravarthy DP 《The Review of scientific instruments》2008,79(4):045104
A design approach giving the optimum number of stages in a magnetic pulse compression circuit and gain per stage is given. The limitation on the maximum gain per stage is discussed. The total system volume minimization is done by considering the energy storage capacitor volume and magnetic core volume at each stage. At the end of this paper, the design of a magnetic pulse compression based linear induction accelerator of 200 kV, 5 kA, and 100 ns with a repetition rate of 100 Hz is discussed with its experimental results. 相似文献
24.
Praveen C. Ramamurthy Ashwini N. Mallya Alex Joseph William R. Harrell Richard V. Gregory 《Polymer Engineering and Science》2012,52(8):1821-1830
High molecular weight polyaniline (PANI) was synthesized by a combined procedure incorporating various synthesis methods. Temperature and open circuit potential of the reaction mixture were collected to monitor the reaction progress. The polymer is characterized by various techniques including gel permeation chromatography, dynamic light scattering, infrared spectroscopy, solid‐state nuclear magnetic resonance, and differential scanning calorimetry for elucidating the molecular architecture obtained by this method. As‐synthesized PANI was found to possess high molecular weight, reduced branching, reduced cross‐linking, and to predominantly consist of linear polymer chains. This polymer was also found to be more stable in solution form. J–V characteristics of as‐synthesized PANI films indicate a high current density which is due to increased free pathways and less traps for the charge transport to occur in PANI films. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers 相似文献
25.
26.
Praveen Siluvai Antony Rajiv Ananth Sohony Rajesh B. Biniwale 《International Journal of Hydrogen Energy》2014
A mathematical model has been developed to study the impact of nozzle-catalyst distance and bulk gas temperature on the conversion and hydrogen evolution rate in a spray pulse reactor. The effects of reactor configuration and operating parameters on conversion and evolution rate were predicted with more than 90% accuracy. Reactor optimization and sensitivity analysis were carried out and an optimal design of nozzle-catalyst distance 5 cm and bulk gas temperature of 50 °C were proposed. The optimized design was predicted to increase the conversion from approximately 32–74%. The model could be in general used for designing any endothermic heterogeneous catalytic reaction in a spray pulse reactor. 相似文献
27.
28.
Hebbar Narayana Praveen B. M. Prasanna B. M. Sachin H. P. 《Journal of Failure Analysis and Prevention》2018,18(2):371-381
Journal of Failure Analysis and Prevention - The inhibition effect of Flectofenine on corrosion of mild steel in 1M HCl solution was investigated by using traditional weight loss method and... 相似文献
29.
Kumar Rajwardhan Pal Sanjit Kumar Gupta Praveen Kumar 《Mine Water and the Environment》2021,40(3):622-638
Mine Water and the Environment - Seepage of water through an underground coal-mine barrier is a common indicator of a potential hydrogeological hazard. The Jharia coalfield has witnessed several... 相似文献
30.
Sanjeev Kumar Pandey S. L. Patil Praveen V. Pol S. B. Phadke 《International Journal of Electronics》2020,107(10):1682-1703
ABSTRACT In this paper, two control schemes for boost converters affected by uncertainties in input voltage and load are proposed. The boost converter dynamics is redefined in terms of new state variables to facilitate the use of a disturbance observer that can estimate matched and unmatched disturbances. A sliding surface, which is new in the context of boost converters, is proposed to enable tracking and regulation of output voltage without requiring measurement of input voltage and load current. The stability of the overall system including the disturbance observer, the sliding variable and the output is proved. The performance of the schemes is assessed for regulation of output voltage and tracking of reference voltage by simulation as well as experimentation in which various types of uncertainties and various types of reference voltages are considered. 相似文献