Wyniki wyszukiwania - BazTech

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Multiple-warehouse sliding mode control with a predefined demand trajectory profile

Adamiak Katarzyna, Zwierzchowski Tymoteusz

International Journal of Applied Mathematics and Computer Science

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2024

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Vol. 34, no. 3

375--389

EN

The paper discusses the inventory management problem with a single product stored in two warehouses, where each has its unique suppliers with certain lead times. Moreover, one of the warehouses may act as a backup supplier for the other. In other words, product exchange between two different warehouses within one company is allowed. The first warehouse operates under an a priori known time-variant contractual demand and a bounded random one. Its secondary goal is to accumulate emergency stock that can be delivered to the second warehouse within one time period. For this warehouse we use a desired trajectory generator to shape the required stock level and then utilize a trajectory following control law. The demand in the second warehouse is unknown but bounded, and its suppliers have limited delivery capacity. The challenge is to fulfill the customers’ needs, although they might exceed the order limit. Therefore, occasional backup supplies from the first warehouse are necessary. For the control of the second warehouse, a simple sliding mode (SM) scheme is applied. The paper proves that, with appropriate compensation of the emergency deliveries in the first warehouse, our proposed control scheme ensures full demand satisfaction in both warehouses despite the second one’s control limit.

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Fish collagen and chitosan mixtures as a promising biomaterial for potential use in medicine and cosmetic industry

Sionkowska Alina, Musiał Katarzyna, Gadomska Magdalena, Adamiak Katarzyna

Engineering of Biomaterials

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2022

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vol. 25, no. 164

16--24

EN

For the last three decades, an increasing interest in new materials based on blends of two or more polymers has been observed. Fish skin collagen and chitosan are constantly highly popular among scientists. This study aimed to obtain thin films from mixtures of low and medium molecular weight chitosan with fish collagen in three different ratios and examine their features for potential use in medicine and cosmetic industry. Polymer blends in ratios 25:75, 50:50, and 75:25 were made to obtain thin films. The infrared spectroscopy, mechanical properties study, contact angle measurements, topographic imaging, and swelling test were used to characterize the features of the films. A statistical appraisal of the results was conducted with the Q-Dixon’s test. The infrared spectroscopy analysis showed that in the IR spectra of the examined biomaterials, there are shifts in the bands positions proving intermolecular interactions between collagen and chitosan in the blends. The mechanical properties in the mixtures were different from those of a single biopolymer film. Hydrophilicity and polarity of the blends decrease with the increasing collagen content, which may suggest that the adhesion to the skin will be enhanced. The surface topography of the obtained films varies depending on the ratio of biopolymers in the mixtures. The swelling tests indicated that chitosan absorbs more water than collagen. The properties of the films made of collagen-chitosan mixtures vary depending on the molecular weight of chitosan and the content of each biopolymer in the blend.

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Modification of chitosan films with fish skin collagen

Sionkowska Alina, Musiał Katarzyna, Gadomska Magdalena, Adamiak Katarzyna

Engineering of Biomaterials

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2021

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Vol. 24, no. 163

90

4

Rheological properties of collagen gels after UV treatment

Sionkowska Alina, Adamiak Katarzyna, Lewandowska Katarzyna

Engineering of Biomaterials

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2020

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Vol. 23, no. 158 spec. iss.

9

5

A reference trajectory based discrete time sliding mode control strategy

Bartoszewicz Andrzej, Adamiak Katarzyna

International Journal of Applied Mathematics and Computer Science

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2019

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Vol. 29, no. 3

517--525

EN

This study presents a new, reference trajectory based sliding mode control strategy for disturbed discrete time dynamical systems. The desired trajectory, which is generated externally according to an existing switching type reaching law, determines the properties of the emerging sliding motion of the system. It is proved that an appropriate choice of the trajectory generator parameters ensures the existence of the quasi-sliding motion of the system according to the definition by Gao et al. (1995) in spite of the influence of disturbances. Moreover, the paper shows that the application of the desired trajectory based reaching law results in a significant reduction in the quasi-sliding mode band width and errors of all state variables. Therefore, in comparison with Gao’s control method, the system’s robustness is increased. The paper also presents an additional modification of the reaching law, which guarantees a further reduction in the quasi-sliding mode band in the case of slowly varying disturbances. The results are confirmed with a simulation example.