The analysis of renal artery cross-section area and kidney volume in computed tomography angiography

Background: The purpose of this study was to assess the relationship between renal artery cross-section area and kidney volume with consideration of anatomical variants of renal arteries, sexual dimorphism and lateralisation. Materials and methods: Two hundred and two patients, 104 women and 98 men, aged 57.3 ± 16 years were examined using computed tomography angiography (CTA) of abdominal aorta for various reasons. The cross-section areas of renal arteries were measured automatically with a vessel tracking programme and summed up on each side in case of the presence of additional renal arteries. The kidneys were measured manually. Results: Additional renal arteries (ARA) were found in 68 (33.7%) patients. Fifty-three (77.9%) of them had one, 11 (16.2%) two and 4 (5.9%) three ARAs. Bilateral ARAs occurred in 10 cases (14.7% patients with ARA). Proximal branching of renal artery occurred in 36 (8.4%) renal arteries. The cross-section area of the largest renal artery depended on the number of ipsilateral renal arteries. Mean cross-section area of the main left renal artery was larger than on the right side (28.52 mm2 vs. 25.36 mm2, p < 0.01) in the whole analysed group. Strong sexual dimorphism in renal artery cross-section area was observed (p < 0.01) in favour of men (31.3 mm2 in men and 22.9 mm2 in women). Mean total renal artery cross-section area has positively correlated with kidney volume (p < 10–13) in both sexes with Pearson correlation value of 0.5. Conclusions: The cross-section area of renal arteries correlated positively with kidney volume in both sexes. Presence of ARAs does not influence the sum of cross-section areas of renal arteries. In case of a difference between left and right renal artery cross-section area with symmetrical kidneys, it is necessary to look for ARA

Stability of inverter fed induction motor

W artykule zamieszczono wstępne wyniki badań analizy stabilności silnika indukcyjnego zasilanego z falownika napięcia. Przedstawiono model matematyczny silnika indukcyjnego oraz określono warunki pracy układu przyjmując założenia dla wyznaczenia równań opisujących pracę układu napędowego w stanie ustalonym. Określono transmitancję silnika indukcyjnego w celu wyznaczenia zakresu jego stabilnej pracy. Wykazano możliwość wystąpienia niestabilnej pracy układu z silnikiem indukcyjnym zasilanym z falownika napięcia.The preliminary results of stability analysis of control system for inverter fed induction motor are presented. The mathematical model of induction motor is presented as well as working conditions of the system are defined with steady state assumption for electric drive equations. The transmittance of induction motor was determined to specify the stability range. Possibility of instability of control system for inverter fed induction motor is proofed

Sensorless field oriented control for five-phase induction motors with third harmonic injection and fault insensitive feature

The paper presents a solution for sensorless field oriented control (FOC) system for five-phase induction motors with improved rotor flux pattern. In order to obtain the advantages of a third harmonic injection with a quasi-trapezoidal flux shape, two vector models, α1–β1 and α3–β3, were transformed into d1– q1, d3– q3 rotating frames, which correlate to the 1st and 3rd harmonic plane respectively. A linearization approach of the dual machine model in d – q coordinate frames is proposed by introducing a new additional variable “x” which is proportional to the electromagnetic torque. By applying the static feedback control law, a dual mathematical model of the five-phase induction motor was linearized to synthesize a control system in which the electromagnetic torque and the rotor flux can be independently controlled. The results shows the air gap flux shape in steady as well transient states under various load conditions. Moreover, the implemented control structure acquires fault tolerant properties and leads to possible emergency running with limited operation capabilities. The fault-tolerant capability of the analyzed machine was guaranteed by a special implemented control system with a dedicated speed observer, which is insensitive to open-phase fault situation. The experimental tests have been performed with single and double-open stator phase fault. A torque measurement was implemented to present the mechanical characteristics under healthy and faulty conditions of the drive system

Sensorless low speed PMSM control with cogging torque compensation

W pracy przedstawiono propozycję rozwiązania problemu bezczujnikowego sterowania wolnoobrotową maszyną synchroniczną z magnesami trwałymi PMSM. Przedstawiono silnik PMSM, który zastosowano w stanowisku badawczym. Omówiono problem występowania tętnień momentu napędowego wynikający głównie ze znacznego momentu zaczepowego. Pokazano rozwiązanie kompensujące tętnienia momentu napędowego w silniku PMSM. Przygotowano procedurę startową układu regulacji prędkości pozwalającą na uruchomienie napędu bez czujników prędkości i położenia. Do sterowania silnikiem użyto metodę sterowania polowo zorientowanego z regulatorami PI prądów stojana w osiach dq. Przedstawiono zależności nowej, prostszej wersji obserwatora stanu. Pokazano wyniki eksperymentów potwierdzających poprawne działanie napędu.The paper presents a possible implementation of a sensorless low speed permanent magnet synchronous machine (PMSM) control. The test setup for this purpose consists of an individual and programmable back-to-back voltage inverter and a PMSM with nominal power of 12 kW and nominal speed of 600 rpm. The impact of cogging torque oscillations is identified, which cause significant problems in the implementation of a Field Oriented Control for low speed PMSM. In order to handle this torque oscillation problem a compensation method is proposed as well. A start-up procedure for the control system was implemented that allows a motor start without any rotor angle and speed sensors. The presented control method is based on the Field Oriented Control with PI stator current controllers in dq axes. Furthermore, the equations of the applied state observer are shown. The observer estimates all of the control variables necessary using phase current measurement and the information of the desired stator voltage. All theoretical assumptions are verified with experimental results, which show the proper operation of the low speed PMSM drive

Persistent trigeminal artery as a rare cause of vertebrobasilar insufficiency

The persistent trigeminal artery (PTA) is the most common fetal carotid- basilar anastomosis which may persist into adult life. In the literature there are numerous papers referring to the anatomical characteristics of this anomalous vessel. In the majority of cases PTA is an incidental finding and its clinical significance has been debated. Some authors describe the coincidence of PTA with various clinical syndromes. However, there are few reports linking PTA with the symptoms of vertebrobasilar insufficiency. We present a patient with a 3-year history of recurrent dizziness and impaired vision, precipitated by physical activity, in whom neuroimaging techniques revealed a persistent left trigeminal artery (PTA). In our case the occurrence of PTA might have been related to the clinical manifestation and the potential mechanism will be discussed

Ion-selective electrodes based on p-tert-butyl-homooxacalixarene di(ethyl)amides

A series of sandwich, monomeric, dimeric and polymeric complexes supported with 1,8-xanthone-18-crown-5 (L) were synthesised. Mass spectrum experiments suggested the existence of sandwich and monomeric complexes in solution. And the structure characterisations of six new complexes by single-crystal X-ray diffraction show the strong coordination of xanthone-18-crown-5 carbonyl oxygen with alkaline earth metal cation, which results high fluorescent increase in alkaline earth metal complexes.. - Polish Ministry of Higher Education and Science [N N204 274235]. - Financial support from the Polish Ministry of Higher Education and Science, Grant No. N N204 274235, is gratefully acknowledged. We also thank Dr J. Chojnacki from Gdansk University of Technology for X-ray crystal structure determination

Critical ischemia of the fingers in an auto mechanic as a result of occupational exposure

Hypothenar hammer syndrome is a rare cause of ischemic fingers observed mainly in young men smoking cigarettes and it is associated with repeated trauma of the ulnar artery in the area of the hypothenar eminence of the dominant-hand arm, resulting in a deficit of blood supply with the occurrence of hand symptoms typical for chronic and sometimes critical ischemia. Artery injury in this location is most often the result of multiple repetitions of the same activity being mostly the result of occupational exposure. We present a case of a 27-year-old car mechanic admitted to the hospital with symptoms of critical ischemia of the fingers III, IV, and V of the right hand, which resolved after conservative treatment