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Metoda komputerowego wspomagania wyznaczania harmonogramów pracy pojazdów kolejowych z uwzględnieniem zajętości torów postojowych

Piętka R., Ambroziak T.

Prace Naukowe Politechniki Warszawskiej. Transport

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2013

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z. 97

411--419

PL

Harmonogramy pracy pojazdów kolejowych możemy uzyskać stosując metodę tzw. mini-obiegów. W artykule przedstawiono sposób uwzględnienia w modelu matematycznym problemu zajętości torów postojowych.

EN

Applying the method of so-called mini-circulations we can get the schedules of the work of traction vehicles. Approach to the problem secondary tracks occupancy in mathematical model is presented in this paper.

2

Metoda komputerowego wspomagania wyznaczania harmonogramów pracy pojazdów trakcyjnych

Ambroziak T., Piętka R.

Prace Naukowe Politechniki Warszawskiej. Transport

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2008

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z. 64

13-18

PL

W artykule przedstawiona została propozycja metody komputerowego wspomagania wyznaczania harmonogramów pracy pojazdów trakcyjnych. W szczególności został przedstawiony model matematyczny zagadnienia przydziału pojazdów trakcyjnych do realizowanych zadań przewozowych. Harmonogramy pracy pojazdów trakcyjnych uzyskujemy stosując metodę tzw. mini-obiegów.

EN

The proposal of the method of the computer aid of marking the schedules of the work of traction vehicles was introduced in the article. He became in the peculiarity introduced the mathematical model of the question of the allotment of traction vehicles [o realized transport tasks. Applying the method of so-called mini-circulations we get the schedules of the work of traction vehicles.

3

Metoda wyznaczania suboplymalnych planów pracy pojazdów (składów)

Ambroziak T., Piętka R.

Prace Naukowe Politechniki Warszawskiej. Transport

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2007

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z. 63

15-23

PL

Wśród problemów związanych z planowaniem organizacji transportu kolejowego jednymi z ważniejszych są problemy przydziału pojazdów. W artykule zaproponowano sformułowanie problemu przydziału pojazdów do pociągów w kontekście transportu pasażerskiego bazując na aparacie matematycznym zagadnienia przepływu w sieci.

EN

The vehicle scheduling problems (or the vehicle assignment problems) are among the most important problems in railroad scheduling. In this paper, we propose a network flow-based formulation for assigning vehicles to trains in the context of passenger transportation.

4

Metoda wyznaczania górnego ograniczenia dla całkowitej liczby odbiorców w problemach trasowania pojazdów z ograniczeniami czasowymi oraz ograniczoną liczbą pojazdów

Ambroziak T., Piętka R.

Prace Naukowe Politechniki Warszawskiej. Transport

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2007

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z. 60

47-53

PL

W artykule przedstawiono metodę wyznaczania górnego ograniczenia całkowitej liczby odbiorców możliwych do obsłużenia daną ograniczoną liczbą pojazdów w problemach trasowania pojazdów z ograniczeniami czasowymi oraz ograniczoną liczbą pojazdów.

EN

This paper introduces a variant of the vehicle routing problem with time windows where a limited number of vehicles is given. There is also presented the method of determining an upper bound for the total number of customers that can be served by a given fixed number of vehicles.

5

On the gelation of profens as a property causing their oscillatory transenantiomerization

Sajewicz M., Piętka R., Kuś P., Kowalska T.

Acta Chromatographica

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2006

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No. 16

181-191

EN

We have previously revealed, for the first time, the tendency of some profens (S-(+)-ibuprofen, S-(+)-naproxen, and S,R-(š)-2-phenylpropionic acid) to undergo oscillatory transenantiomerization when dissolved in some low-molecular-weight solvents. Such oscillatory reactions, which are relatively rare among chemical reactions, can be stimulated by several different physical and chemical conditions. It was the objective of this study to reveal the reason for the oscillatory transenantiomerization of profens. The analytical techniques used in our study embraced measurement of the viscosity of the profen solutions and acquiring their HPLC chromatograms and 1H NMR spectra. It has been firmly established that the physical property leading to oscillatory transenantiomerization of the profens is their ability to act as low-molecular-weight gelators, which results in substantial differences between the viscosity of their solutions and that of the pure solvents. One well-known cause of oscillatory reactions is diffusion-driven instability which appears in the form of oscillations. This occurs when, because of high solution viscosity, the rate of diffusion of an intermediate reaction product becomes less its rate of formation. For the profens investigated it seems most likely that their ability to substantially increase the viscosity of the solution results in the rate of diffusion of an intermediate keto–enol product being lower than its rate of formation from the respective profen enantiomer.

6

Application of thin-layer chromatography (TLC) to investigating oscillatory instability of the selected profen enantiomers

Sajewicz M., Piętka R., Pieniak A., Kowalska T.

Acta Chromatographica

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2005

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No. 15

131-149

EN

In our earlier studies we intended to evaluate the performance of thin-layer chromatography (TLC) as an analytical tool applied to separation of the selected profen (i.e. 2-arylpropionic acid) enantiomers and we se-lected ibuprofen as a model analyte for this purpose. Surprisingly enough, TLC is relatively seldom used for separation of enantiomers, even though – despite the low number of theoretical plates (N) in this particular techni-que in comparison with fully automated column chromatographic techni-ques (basically GC and HPLC) – it seems very well suited for complete separation of two analytes only (i.e. a pair of enantiomers). Separation of profens can be regarded as a particularly urgent ana-lytical task, because they are among the most widely prescribed synthetic non-steroidal anti-inflammatory drugs and in medicinal chemistry we must be vigilantly aware of possible unpredictable consequences of dispensing medicines as racemic mixtures. In earlier and in more recent studies we have provided enough evi-dence not only to prove that the analytical performance of TLC is suffi-cient for separation of the enantiomers of ibuprofen, but also – even more important – to demonstrate the usefulness of this simple yet very efficient separation technique in physicochemical studies of the oscillatory instability of profens when stored for long periods of time in aqueous media. By use of TLC it was possible to show the oscillatory transenantiomerization of the profens from the S to the R form, and vice versa, during storage. The correctness of our TLC assessment with regard to structural oscillation of enantiomeric profens was later successfully confirmed by means of pola-riemetry.

7

Zagadnienie przewozów terminowych. Sformułowanie zadania optymalizacyjnego, metoda rozwiązania

Piętka R.

Zeszyty Naukowe. Transport / Politechnika Śląska

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2004

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z. 52

395-402

PL

W poniższym artykule przedstawiony został problem organizacji przewozów pasażerów "od drzwi do drzwi", a w szczególności problem dekompozycji zleceń na przewozy zamknięte, występujący w tym zagadnieniu.

EN

This paper presents the "door to door" passenger service problem with time windows and suggests of a method decomposition of transportation requests.

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Densitometric acquisition of concentration profiles in planar chromatography and its possible shortcomings. Part 1. 4-phenylbutyric acid as analyte

Sajewicz M., Pieniak A., Piętka R., Kaczmarski K., Kowalska T.

Acta Chromatographica

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2004

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No. 14

5-15

EN

In this paper we describe part of a study originally devoted to inve-stigating lateral interactions of 4-phenylbutyric acid in 'mild' chromatogra-phic systems comprising low-activity stationary phases (microcrystalline cellulose or chromatography paper) and low-polarity decalin as mobile phase. The presence or absence of lateral interactions of an analyte in a given chromatographic system can be judged from the shape of the concentration profile and for this purpose densitograms of the bands of interest must first be acquired. Our attention was unexpectedly attracted by a largely surprising observation that the concentration profile of 4-phe-nylbutyric acid on cellulose powder could be measured easily on a freshly developed chromatogram only after drying whereas on chromatography paper developed at room temperature it was hardly detectable, and became fully shaped only two days later. To explain this striking phenomenon we had to perform several additional experiments and, although the final answer is not fully conclusive, a tentative explanation can already be presented.