Search results

Filters

  • Journals
  • Keywords
  • Date

Search results

Number of results: 14
items per page: 25 50 75
Sort by:

Abstract

The suburb of Kalisz, called the Old Town, is a historical craft and trade settlement located near the ducal castle — the early medieval town of Kalisz. In 2001, during archaeological excavations a number of coins were discovered at this location. Six of them are the subject of this paper. They are bracteates struck in the second half of the 13th century, probably in Greater Poland during the reign of Przemysł II (†1296).
Go to article

Abstract

Eight coins (seven medieval and one modern) were found during archaeological rescue excavation on the Main Market Square in Kalisz in 2012. Four coins (including one fragment) are hohlpfennigs, probably all of them are of Polish origin (from Greater Poland?) and date from the thirteenth-fourteenth century. The next three are: a halved penny, perhaps from the end of the thirteenth century, West Pomeranian penny and, probably, a Silesian heller from the fourteenth-fifteenth century. The modern coin is a heavily worn copper shilling by John Casimir (1648–1668).
Go to article

Abstract

Archaeological excavations conducted recently in Kalisz brought about two groups of Jagiellonian pennies. One is a small hoard of less than twenty coins of Vladislaus Jagiełło, found near the St. Joseph Sanctuary. The other comprises 37 coins found separately in archaeological excavations at early mediaeval settlement known as Stare Miasto (Old Town), adjacent to the hillfort at Zawodzie.
Go to article

Abstract

Hydraulic fracturing of rocks boosts the production rate by increasing the fracture-face surface area through the use of a pressurized liquid. Complex stress distribution and magnitude are the main factors that hinder the use of information gathered from in situ hydraulic fracturing in other locations. Laboratory tests are a good method for precisely determining the characteristics of these processes. One of the most important parameters is breakdown pressure, defined as the wellbore pressure necessary to induce a hydraulic fracture. Therefore, the main purpose of this investigation is to verify fracture resistance of rock samples fractured with the assistance of the most popular industry fluids. The experiments were carried out using a stand designed specifically for laboratory hydraulic fracturing. Repeatable results with a relative error within the range of 6-11% prove that the experimental methodology was correct. Moreover, the obtained results show that fracturing pressure depends significantly on fluid type. In the case of a water test, the fracturing pressure was 7.1±0.4 MPa. A similar result was achieved for slickwater, 7.5±0.7 MPa; however, a much lower value (4.7±0.5 MPa) was registered in the case of carbon dioxide.
Go to article

Abstract

The aim of the study is to identify the relevant aspects of numerical analysis of impact of projectiles with soft cores into a package composed of thin flexible plies located on the plastic backing. In order to illustrate the problem, normal impact of 7.62 mm TT projectile into an unclamped package comprising 36 plies of Dyneema SB71 supported on the plastic backing was selected. The problem was solved with the use of the finite element method (FEM) with the explicit integration scheme (central difference method) of motion equations in the matrix form. Based on the conducted numerical computations, it was revealed that obtaining the extreme deformations of a projectile soft core and the backing material in Lagrangian description requires employment of adaptive methods. The proposed R-adaptive method performs its role but must be used carefully due to the mass loss which may appear during calculations.
Go to article

Abstract

The article describes the process of creating 3D models of architectural objects on the basis of video images, which had been acquired by a Sony NEX-VG10E fixed focal length video camera. It was assumed, that based on video and Terrestrial Laser Scanning data it is possible to develop 3D models of architectural objects. The acquisition of video data was preceded by the calibration of video camera. The process of creating 3D models from video data involves the following steps: video frames selection for the orientation process, orientation of video frames using points with known coordinates from Terrestrial Laser Scanning (TLS), generating a TIN model using automatic matching methods. The above objects have been measured with an impulse laser scanner, Leica ScanStation 2. Created 3D models of architectural objects were compared with 3D models of the same objects for which the self-calibration bundle adjustment process was performed. In this order a PhotoModeler Software was used. In order to assess the accuracy of the developed 3D models of architectural objects, points with known coordinates from Terrestrial Laser Scanning were used. To assess the accuracy a shortest distance method was used. Analysis of the accuracy showed that 3D models generated from video images differ by about 0.06 ÷ 0.13 m compared to TLS data.
Go to article

This page uses 'cookies'. Learn more