This paper suggests a new algorithm for data compression that depends on Boolean minimization of binary data. On the compressor side, the input bit-stream is chopped into chunks of 16-bit each, and a "sum of products" function is found for each chunk of bits using the Quine-McClusky algorithm. The minimized "sum of products" function is stored in a file. Later, the Huffman coding is applied to this file. The obtained Huffman code is used to convert the original file into a compressed one. On the decompression side, the Huffman tree is used to retrieve the original file. The experimental results of the proposed algorithm showed that the saving ratio on average is around 50%. In addition, the worst case was investigated and a remedy to it was suggested. The proposed technique can be used for various file formats including images and videos.
During an experiment to transmit Tetracapsula bryosalmonae Canning, Curry, Feist, Longshaw et Okamura, 1999 to a laboratory-cultured bryozoan, Plumatella repens L. a previously undescribed malacosporean species was noted. This parasite produced sacs of spores in the host that reached 1.2 mm in length. The spores released from the sacs appeared similar in size to the two species of Tetracapsula previously described although slight differences in form were noted. Release of spores from the bryozoans was observed associated with the lophophore of the host. The use of experimental bryozoan cultures for the examination of malacosporeans is described and discussed.
This paper describes the contacts the lecturers of the Czech Technical University had with third world countries in the 1960s. The general processes in preparing these contacts in Czechoslovakia are described, together with the specific strategy of the school and its lecturers.
The finite volume method is applied for solving the conservative Saint-Venant equations in case of a one-dimensional open channel flow with high temporal and spatial variability. A new shock-capturing discretisation scheme is proposed for computation of flow equations with source terms. The proposed scheme, called hybrid, combines adventages of flux-splitting and flux-difference-splitting schemes. Five benchmark tests are used to verify the hybrid scheme. The tests are: (1) Flow in a rectangular cross-section rough channel, (2) instantaneous dambreak over an horizontal, initially dry bed, (3) undercritical flow over a bump, (4) undercritical flow over a bump with change to supercritical flow, and (5) supercritical flow over a bump with hydraulic jump. The quality of the proposed scheme is evaluated and compared with that of well known flux-splitting and flux-difference-splitting schemes, on the base of the average percentual error. Results show that the hybrid scheme has a good precision for calculation of highly unsteady, varied flow and that the model is able to consider a partially dry bed. The average percentual errors of the computations ranged from 0.0 to 5.4 % for flow depth and from 0.0 to 6.3 % for specific discharge. and Metoda konečných objemů se používá při řešení Saint-Venantových rovnic pro jednorozměrné proudění v otevřeném kanále a při velkých časových a prostorových změnách. V práci je navrženo nové diskretizační schéma schopné zachytit rázové jevy pro řešení tokových rovnic se zdrojovými členy. Navržený postup nazýváme hybridním, neboť kombinuje výhody modelování pomocí dvou schémat, nazývaných fluxsplitting a flux-difference-splitting. Pro ověření hybridního schématu bylo testováno pět různých uspořádání. Byly zkoušeny: 1. proudění v drsném korytě s obdélníkovým průřezem, 2. okamžitý vtok do horizontálního původně suchého koryta, 3. podkritické proudění přes práh, 4. podkritické proudění přes práh s přechodem na nadkritické proudění a 5. nadkritické proudění přes práh s hydraulickým skokem. Kvalita navrženého postupu je vyhodnocena a porovnána s výsledky získanými pomocí známých výše uvedených schémat. Byly vyhodnoceny průměrné chyby v procentech. Výsledky naznačují, že hybridní schéma vykazuje dobrou přesnost při výpočtu neustáleného, proměnlivého proudění, a že tento model je schopen vzít v úvahu částečně suché koryto. Průměrné chyby v procentech se pohybovaly od nuly do 5,4 % pro hloubku a od nuly do 6,3 % pro specifický průtok.
Mining-induced ground fissure (MIGF) contributes to vegetation deterioration, landslides and other natural hazards. The study is an attempt to reveal the development type, dynamic development process, and formation mechanism of MIGF for MIGF-induced natural hazard prevention of shallow burial coal seam mining. A novel approach including in situ measurement, theoretical analysis, and numerical simulation was implemented. There are two typical types of fissures, namely sliding-type ground fissures and stepped-type ground fissures. Sliding-type ground fissures generally develop in a mountainous slope with a large gradient while steppedtype ground fissures typically occur in a mountainous slope with a small gradient and especially near a valley. Dynamic development process of MIGF is significantly affected by roof periodic movement. The advancing distance of a sliding-type ground fissure is 1.35 times periodic weighting step distance while it corresponds to 0.89 times the periodic weighting step distance for a stepped-type ground fissure. A positive relationship exists between horizontal tensile deformation and MIGF width. The movement mode of “voussoir beam” is favorable for slidingtype ground fissure development while the movement mode of “stepped beam” leads to steppedtype ground fissure development. These results can contribute to MIGF treatment and ecological protection in the southwestern mountainous area.