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Cezary Specht and Marcin Skóra

Abstract

The previous measurement campaigns planning used in geodesy is conducted exclusively for individual points. For the natural process aimed at the adoption of the introduction of the planning (prediction of constellation state) in navigation, which is characterized by the movement, one should adopt measurement campaigns planning for linear objects. In contrast to the existing planning solutions, focused on point presentation of the state of the constellation of navigation system, the author of this article rearranges the proposal of determination of geometrical factors, and their summation. In the presented simulation, one has specified the route of passing at certain times and it was assumed that the receiver will move with variable motion. One has defined the geometric ratios (PDOP), which allow to distinguish the results corresponding to the adopted criteria for the measurement of linear object to be conducted with the best possible accuracy.

Open access

Cezary Specht, Mateusz Mania, Marcin Skóra and Mariusz Specht

Abstract

A possibility of utilising the GPS system for navigation and transport are fundamentally dependent on the accuracy in positioning. Two fundamental factors decisive for its value are the values of the User Range Error (URE) and Dilution of Precision (DOP), strictly related to the number of satellites forming the constellation. The nominal constellation of GPS satellites consists of 24 units which gives a possibility of identification of coordinates all over the globe. In the last few years, however, the nominal number of satellites in the constellation was much higher, and the URE value has been constantly increasing.

The authors of the paper try to estimate the impact of the changing number of GPS satellites on accuracy of position coordinates with a variable URE value. Mathematical model for estimating geometrical indicators’ value, utilising data derived from the almanac files has been presented. Following a drawn-up algorithm and calculations made with Mathcad software, the authors carried out a comparative analysis of mean daily values of DOP indicators for a variable number of satellites included in the GPS constellation in the years 2001-2013. Then, the authors have established representative values of Two Distance Root Mean Square Error (2drms) 2D and 3D, and calculated a percentage increase of accuracy in the period under discussion.

Open access

Dariusz Janczak, Jan Skóra, Jerzy Garcarek, Marcin Merenda and Andrzej Litarski

Rusults of Classical Crawford and Hybrid Operations in Thoracic-Abdominal Aorta Aneursysms Treatment - Comperative Assesment

Thoracic-abdominal aortic aneurysms (TAAA) are still serious medical problem. Classical procedure requires two cavities approach and implantation of vascular prosthetic in the place of aneurysm - Crawford's procedure. Significant progress was made during last years by using endovascular procedures (stentgrafts). Alternative is hybrid procedure - prosthetic appliance of visceral and kidney arteries and then stentgraft implantation in whole thoracic-abdominal aorta.

The aim of the study was comparative analysis of classical and hybrid procedures in thoracic-abdominal aneurysms treatment.

Material and methods. Between 1989-2011 in Department of Vascular, General and Transplantological Surgery Medical University in Wrocław and Surgical Department of 4th Military Clinical Hospital in Wrocław 53 patients were operated due to thoracic-abdominal aortic aneurysms. Classical Crawford's procedure was performed in 41 patients (group I) and hybrid procedure was performed in 12 patients (group II). Additionally 7 patients required aortic arc branches reconstruction due to achieve optimal conditions to stentgraft amplantation. Procedures were performed at one or two stages.

Results. Mortality in patients treated classically (group I) depended on type of aneurysm in Crawford's classification. In type I-II mortality rate was 54% ((7 deaths/12 patients), in type III do V 17% (5 deaths/ 29 patients). In the group after hybrid procedure (group II) mortality rate was 28% (2 deaths/ 7 patients) in type I-II and 20% (1 death/5 patients) in type III to V. Observed serious perioperative complications.

Conclusions. 1. Endovascular procedures development enabled introducing of new methods in thoracic-abdominal aortic aneurysms treatment (hybrid procedures) and allowed to get better results. 2. Clear advantage of hybrid procedures above classical Crawford's procedure is observed in type I and II of TAAA. 3. Mortality and morbidity rates recommend hybrid procedure in type I and II of TAAA. 4. Surgical results of classical and hybrid procedures in type III-V TAAA treatment are comparative, with indication on classical approach.

Open access

Dariusz Janczak, Piotr Janczak, Jan Skóra, Karolina Dorobisz, Marcin Merenda, Andrzej Litarski and P. Szyber

Abstract

Inflammatory mediators play an important role in thrombosis etiopathology. Diagnostic radioisotopic tests can be used to assess the activity of thrombo-inflammatory process.

The aim of the study was to assess the suitability of Tc-99m HMPAO labelled leukocyte scintigraphy in the diagnostics of deep vein thrombosis.

Material and methods. The study covered 45 patients with lower limb deep vein thrombosis treated in 2009 at the Department of Vascular, General and Transplantological Surgery of the Wrocław Medical University. Scintigraphic test were performed during the first few days after the onset of symptoms and 8 weeks later.

Results. All patients with active deep vein thrombosis had higher levels of TC-99m-HMPAO markers in sick limbs. After 8 weeks, 93% of patients still had elevated levels of radioisotope in limbs with an active thrombosis process. However, the levels of markers were clearly lower than in the acute phase of thrombosis.

Conclusions. 1. In the chronic phase of thrombosis, 93% of patients still have higher levels of radioisotopic markers, which indicates an active inflammatory process. 2. Tc-99m HMPAO labelled leukocyte scintigraphy demonstrates high sensitivity in the diagnostics of deep vein thrombosis.