Electrostatic quadrupoles

The equations of motion of the charged particle under the action of electric forces in the simple Electrostatic Quadrupole (ESQ) and in the Helical Electrostatic Quadrupole (HESQ) are solved. The HESQ electric field is realized by the four pole tips forming concentric helices of pitch b. The transformation matrices for ESQ and HESQ are found as the basic elements for designing more complex optical systems

The DRIFT Project: Searching for WIMPS with a Directional Detector

A low pressure time projection chamber for the detection of WIMPs is discussed. Discrimination against Compton electron background in such a device should be very good, and directional information about the recoil atoms would be obtainable. If a full 3-D reconstruction of the recoil tracks can be achieved, Monte Carlo studies indicate that a WIMP signal could be identified with high confidence from as few as 30 detected WIMP-nucleus scattering events.Comment: 5 pages, 3 figures. Presented at Dark 98, Heidelberg, July 1998, and to appear in conference proceeding

Pročišćavanje čelika optimiranjem konfiguracije međulonca

In continuous casting process, liquid steel flows through the tundish, which is supposed to operate as a continuous refining finisher. To provide a functionality of such a device, a pack of tundish metallurgy techniques must be applied, whose efficiency is conditioned especially with optimal symmetrical and dynamical melt flow. Flow optimizing can be achieved through the shaping of inside tundish configuration, using flow control devices such as turbulence inhibitors, impact pads, baffles, weirs, dams, etc. The theme of the present paper is the precise employment of a turbulence inhibitor, commercially known as TURBOSTOPTM, together with a pair of baffles & a flat impact pad in slab custer to improve steel cleanliness and a fluid flow phenomenon in a two strands tundish.Tijekom procesa kontinuiranog lijevanja tekući čelik prolazi kroz međulonac koji funkcionira kao kontinuirani uređaj za završnu doradu rafiniranjem. Za osiguranje funkcioniranja takvog uređaja mora se primijeniti tehnika metalurgije međulonca čija učinkovitost je uvjetovana naročito optimalnim simetrijskim i dinamičkim tečenjem taline. Optimalizacija protoka se može postići oblikovanjem unutrašnje konfiguracije međulonca uporabom takvih uređaja za kontrolu protoka kao što su inhibitori turbulencije, zadebljanje za ublažavanje udaraca, pregradne ploče, brane itd. Tema ovog rada je točna primjena inhibitora turbulencije poznatog pod trgovačkim nazivom TURBOSTOPTM, zajedno s parom skretnih pregrada i ravnim zadebljanjem za ublažavanje udaraca u lijevanom slabu radi poboljšanja čistoće čelika i fenomena toka fluida u dvije žile međulonca

Fast Searching in Packed Strings

Given strings $P$ and $Q$ the (exact) string matching problem is to find all positions of substrings in $Q$ matching $P$. The classical Knuth-Morris-Pratt algorithm [SIAM J. Comput., 1977] solves the string matching problem in linear time which is optimal if we can only read one character at the time. However, most strings are stored in a computer in a packed representation with several characters in a single word, giving us the opportunity to read multiple characters simultaneously. In this paper we study the worst-case complexity of string matching on strings given in packed representation. Let $m \leq n$ be the lengths $P$ and $Q$, respectively, and let $\sigma$ denote the size of the alphabet. On a standard unit-cost word-RAM with logarithmic word size we present an algorithm using time O\left(\frac{n}{\log_\sigma n} + m + \occ\right). Here \occ is the number of occurrences of $P$ in $Q$. For $m = o(n)$ this improves the $O(n)$ bound of the Knuth-Morris-Pratt algorithm. Furthermore, if $m = O(n/\log_\sigma n)$ our algorithm is optimal since any algorithm must spend at least \Omega(\frac{(n+m)\log \sigma}{\log n} + \occ) = \Omega(\frac{n}{\log_\sigma n} + \occ) time to read the input and report all occurrences. The result is obtained by a novel automaton construction based on the Knuth-Morris-Pratt algorithm combined with a new compact representation of subautomata allowing an optimal tabulation-based simulation.Comment: To appear in Journal of Discrete Algorithms. Special Issue on CPM 200