2,003 research outputs found
A New Modified Collection Selection Algorithm using Optimal Term Weight for Web based Applications
As the number of electronic data collections available on the internet increases so does the difficulty of finding the right collection for a given query Often the first time user will be overwhelmed by the array of options available and will waste time hunting through pages of collection names followed by time reading results pages after doing an adhoc search Collection selection using optimal weight methods try to solve this problem by suggesting the best subset of collections to search based on a query This is of importance to fields containing large number of electronic collections which undergo frequent change and collections that cannot be fully indexed using traditional methods such as spiders This paper presents a solution to these problems of selecting the best collections and reducing the number of collections needing to be searche
The Lax conjecture is true
In 1958 Lax conjectured that hyperbolic polynomials in three variables are
determinants of linear combinations of three symmetric matrices. This
conjecture is equivalent to a recent observation of Helton and Vinnikov.Comment: 7 pages, Proceedings to the AMS, to appear. Added background materia
Design of an Implantable Device for Ocular Drug Delivery
Ocular diseases, such as, glaucoma, age-related macular degeneration (AMD), diabetic retinopathy, and retinitis pigmentosa require drug management in order to prevent blindness and affecting million of adults in USA and worldwide. There is an increasing need to develop devices for drug delivery to address ocular diseases. This study focuses on the design, simulation, and development of an implantable ocular drug delivery device consisting of micro-/nanochannels embedded between top and bottom covers with a drug reservoir made from polydimethylsiloxane (PDMS) which is silicon-based organic and biodegradable polymer. Several simulations were carried out with six different micro-channel configurations in order to see the feasibility for ocular drug delivery applications. Based on the results obtained, channel design of osmotic I and osmotic II satisfied the diffusion rates required for ocular drug delivery. Finally, a prototype illustrating the three components of the drug delivery design is presented. In the future, the device will be tested for its functionality and diffusion characteristics
Experimental Evidence of Time Delay Induced Death in Coupled Limit Cycle Oscillators
Experimental observations of time delay induced amplitude death in a pair of
coupled nonlinear electronic circuits that are individually capable of
exhibiting limit cycle oscillations are described. In particular, the existence
of multiply connected death islands in the parameter space of the coupling
strength and the time delay parameter for coupled identical oscillators is
established. The existence of such regions was predicted earlier on theoretical
grounds in [Phys. Rev. Lett. 80, 5109 (1998); Physica 129D, 15 (1999)]. The
experiments also reveal the occurrence of multiple frequency states, frequency
suppression of oscillations with increased time delay and the onset of both
in-phase and anti-phase collective oscillations.Comment: 4 aps formatted RevTeX pages; 6 figures; to appear in Phys. Rev. Let
A Novel Multi-Band Patch Antenna on Metamaterial Substrate for Ku band applications
In this paper, a metamaterial based compact multiband microstrip antenna is proposed which can give high gain and directivity. Metamaterial are periodic structures and have been intensively investigated due to the particular features such as ultra-refraction phenomenon and negative permittivity and/or permeability. A metamaterial based microstrip patch antenna with enhanced characteristics and multi band operation will be investigated in this work. The multiple frequency operation will be achieved by varying the capacitance of the metamaterial structure with the help of metallic loadings placed in each metamaterial unit cells. The potential impacts will be miniaturization, reduced cost and reduced power consumption since multiple antennas operating at different frequencies are replaced by a single antenna which can operate at multiple frequencies. The proposed microstrip patch antenna will have its frequencies of operation in the Ku band. The proposed structure is simulated using HFSS
The number of rational numbers determined by large sets of integers
When and are subsets of the integers in and
respectively, with and , we show that the
number of rational numbers expressible as with in is
for any , where the implied
constant depends on alone. We then construct examples that show that
this bound cannot in general be improved to . We also
resolve the natural generalisation of our problem to arbitrary subsets of
the integer points in . Finally, we apply our results to
answer a question of S\'ark\"ozy concerning the differences of consecutive
terms of the product sequence of a given integer sequence.Comment: 11 page
Quantitative Analysis of AGV System in FMS Cell Layout
Material handling is a specialised activity for a modern manufacturing concern. Automated guided vehicles (AGVs) are invariably used for material handling in flexible manufacturing Systems (FMSs) due to their flexibility. The quantitative analysis of an AGV system is useful for determining the material flow rates, operation times, length of delivery, length of empty move of AGV and the number of AGVs required for a typical FMS cell layout. The efficiency of the material handling system, such as AGV can be improved by reducing the length of empty move. The length of empty move of AGV depends upon despatching and scheduling methods. If these methods of AGVs are not properly planned, the length of empty move of AGV is greater than the length of delivery .This results in increase in material handling time which in turn increases the number of AGVs required in FMS cell. This paper presents a method for optimising the length of empty travel of AGV in a typical FMS cell layout
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