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Andrzej Nowakowski

Abstract

This paper presents the results of laboratory tests carried out in order to formulate effective stress law. The law was sought for two different cases: first - when rock was treated as a porous Biot medium (Biot, 1941; Nur & Byerlee, 1971) and second - when the law was formulated according to definition of Robin (1973) developed by Gustkiewicz (1990) and Nowakowski (2007). In the first case coefficents (4) and (5) of the Biot equation (3) were were determined on the basis of compressibility test, in the second one effective pressure equation (9) and effective pressure value (11) were found on the basis of results of so called individual triaxial compression test (see Kovari et al., 1983) according to the methodology given by Nowakowski (2007).

On the basis of Biot coefficients set of values was found that volumetric strain of the pore space described by a coefficient (5) was not dependent on the type of pore fluid and the pore pressure of only, while in case of volumetric strain of total rock described by coefficient (4) both the structure and texture of rock were important.

The individual triaxial compression test results showed that for tested rock an effective pressure equation was a linear function of pore pressure as (15). The so called Rebinder effect (Rehbinder & Lichtman, 1957) might cause, that the α coefficient in equation (15) could assume values greater than one. This happened particularly in the case when the porous fluid was non-inert carbon dioxide.

In case of inert pore fluid like kerosene the test results suggested that the a coefficient in equation (15) decreased while the differential strength limit was increasing. This might be caused by, so called, dillatancy strengthening (see Zoback & Byerlee, 1975).

Another considered important parameter of the equation (15) was the value of the effective press p'. The results showed that the value of this parameter was practically independend on the pore fluid type. This conclusion was contrary to previous research (see, for example, Gustkiewicz et al., 2003 and Gustkiewicz, 1990) so these results should be treated with caution. There are no doubts, however, over p' increasing simultaneously with increase in 1-σ3. Basically, the differential strength limit of the specimen is greater the greater is confining pressure applied to it. Thus, higher 1-σ3 values are accompanied by higher p'.

Open access

Andrzej Nowakowski and Mariusz Młynarczuk

Abstract

Temperature is one of the basic factors influencing physical and structural properties of rocks. A quantitative and qualitative description of this influence becomes essential in underground construction and, in particular, in the construction of various underground storage facilities, including nuclear waste repositories. The present paper discusses the effects of temperature changes on selected mechanical and structural parameters of the Strzelin granites. Its authors focused on analyzing the changes of granite properties that accompany rapid temperature changes, for temperatures lower than 573ºC, which is the value at which the β - α phase transition in quartz occurs. Some of the criteria for selecting the temperature range were the results of measurements carried out at nuclear waste repositories. It was demonstrated that, as a result of the adopted procedure of heating and cooling of samples, the examined rock starts to reveal measurable structural changes, which, in turn, induces vital changes of its selected mechanical properties. In particular, it was shown that one of the quantities describing the structure of the rock - namely, the fracture network - grew significantly. As a consequence, vital changes could be observed in the following physical quantities characterizing the rock: primary wave velocity (vp), permeability coefficient (k), total porosity (n) and fracture porosity (η), limit of compressive strength (1) and the accompanying deformation (1), Young’s modulus (E), and Poisson’s ratio (ν).

Open access

Marcin Warchałowski, Piotr Nowakowski and Andrzej Dancewicz

Abstract

Relations between climatic factors during the winter season (n days with frost <0oC and −10oC; n days with snow cover: >1 cm, >10 cm and >30 cm; maximum snow cover during season [cm]) and mortality in free-living ungulates (red deer Cervus elaphus Linnaeus, 1758, roe deer Capreolus capreolus Linnaeus, 1758 and mouflon Ovis aries musimon Linnaeus, 1758) in the Owl Mountains (Lower Silesia – Poland) in years 1998–2010 were investigated. Significant effects of all analysed climatic factors on ungulates mortality were documented. Correlations (Pearson) between such weather factors as the depth of snow cover and number of days with frost and recorded mortality in total animal populations analysed ranged from r = 0.33 to r = 0.77. The least adapted to local weather conditions was mouflon introduced to this area ca. 100 years ago from more southern parts of Europe. Roe deer species seems to be environmentally plastic, and are doing quite well in severe winters. Tolerance of red deer to the snow cover is much lower at low temperatures due to the fact that this species, during the period of snow cover, has limited access to the plants covered with snow and difficult access to food base.

Open access

Zbigniew Jakielaszek, Grzegorz Kowaleczko, Andrzej J. Panas and Mirosław Nowakowski

Abstract

The subject of the research was a catastrophic recorder of the S2-3a system for recording flight parameters, developed at the Air Force Institute of Technology. The article discusses tests of catastrophic recorders’ resilience to factors present at aircraft accidents. The document specifying the requirements for catastrophic recorders of flight parameters includes the defence standard: NO-16-A200, and the European standard: EuroCAE ED-112. According to NO-16-A200 and ED-112 standards, the protective unit should be resistant to: g-forces existing during crash, puncture, compression, fire, underwater pressure and aggressive liquids.

Open access

Sławomir Rudzki, Mariusz Matuszek, Andrzej Nowakowski, Beata Matuszek, Przemysław Matras and Katarzyna Wojewoda

Own Experience in Treatment of Autoimmune Goiter in the Last Decade

The aim of the study. The study was intended to be a retrospective analysis of clinical data concerning patients operated on for autoimmune goitre in the period 1998-2008, in the 1st Department of General and Transplant Surgery of the Medical University in Lublin.

Material and methods. 1157 patients were operated on for various goitre forms. This group included 134 patients with Graves' and Hashimoto's disease associated goitre, which accounted for 11% of all goitre patients undergoing the surgery. Major indications to surgical treatment of the Graves' disease included progressive exophthalmos, goitre with compression symptoms, hoarseness, and uncertain biopsy diagnoses. As regards Hashimoto's disease, goitre with compression symptoms or with tumour-like changes, and ambiguous biopsy diagnoses were the factors qualifying the patient for surgical treatment. Statistical analysis was conducted using STATISTICA 6.0 PL software, the chi2 test was performed, and the statistical significance was established at p<0.005.

Results. Graves' disease associated goitre was operated on in 72 patients, including 53 cases (39.5%) where infiltrative ophthalmopathy was also observed. Hashimoto's disease associated goitre was operated on in 62 patients. Early paralysis of the recurrent laryngeal nerve occurred in 10 (13.9%) patients operated on for Graves' disease, and in 5 (8.1%) patients operated on for Hashimoto's disease. As regards patients operated on for non-autoimmune goitre, early paralysis of the recurrent laryngeal nerve was observed in 29 (3%) cases. Post-surgical tetany was observed in 11.1% of Graves' disease patients, and in 8% of Hashimoto's disease patients. Finally, temporary post-surgical tetany was found in 2% of patients with non-autoimmune goitre.

Conclusions. The type of goitre being operated on has a significant impact on the incidence of early post-surgical complications. In general, the incidence of early post-surgical complications is higher in the case of patients operated on for autoimmune-type goitre, compared with patients with non-autoimmune goitre. Yet this method is both safe and efficient. Total thyroid removal should be the treatment applied in the case of progressive orbitopathy associated with Graves' disease.

Open access

Paweł Kroczak, Konstanty Skalski, Andrzej Nowakowski and Adrian Mróz

Abstract

The paper presents an analysis of factors influencing the accuracy of reproduction of geometry of the vertebrae and the intervertebral disc of the lumbar motion segment for the purpose of designing of an intervertebral disc endoprosthesis. In order to increase the functionality of the new type of endoprostheses by a better adjustment of their structure to the patient’s anatomical features, specialist software was used allowing the processing of the projections of the diagnosed structures. Recommended minimum values of projection features were determined in order to ensure an effective processing of the scanned structures as well as other factors affecting the quality of the reproduction of 3D model geometries. Also, there were generated 3D models of the L4-L5 section. For the final development of geometric models for disc and vertebrae L4 and L5 there has been used smoothing procedure by cubic free curves with the NURBS technique.

This allows accurate reproduction of the geometry for the purposes of identification of a spatial shape of the surface of the vertebrae and the vertebral disc and use of the model for designing of a new endoprosthesis, as well as conducting strength tests with the use of finite elements method.