Procjena varijabli stanja sustava s gorivnim člankom i uzlaznim pretvaračem metodom brzog uzorkovanja signala

Estimation of state variables of a peak current mode (PCM) controlled DC-DC boost converter supplied by a PEM fuel cell is described in this paper. Since this system is highly nonlinear and non-minimum phase, its state variables are estimated by using fast output sampling method. Estimated state variables are the converter output voltage and its first derivative, and they are suitable for model reference adaptive control or sliding mode based control techniques. The estimator has been designed in a way that it gives a good estimate of the state variables in the continuous and in the discontinuous conduction mode of the converter, and in the presence of measurement and process noise caused by converter switching-mode operation. Experimental results of estimating the state variables on a 450 W boost converter supplied by the emulator of the PEM fuel cell BCS 64-32 show good results of the estimation, regardless of the conduction mode of the converter, i.e. the operating point determined by its output current.U ovom radu obrađena je procjena varijabli stanja sustava s istomjernim uzlaznim pretvaračem u vršnom strujnom načinu upravljanja napajanim PEM gorivnim člankom. Budući da je taj sustav izrazito nelinearan te neminimalno-fazan, za procjenu njegovih varijabli stanja upotrebljena je metoda brzog uzorkovanja izlaznog signala. Procjenjene varijable stanja su izlazni napon uzlaznog pretvarača te njegova prva derivacija, te su pogodne za adaptivno upravljanje s referentnim modelom i upravljanje temeljeno na kliznim režimima. Procjenitelj je projektiran na način da daje dobru procjenu varijabli stanja u kontinuiranom i diskontinuiranom režimu rada pretvarača, te u uvjetima mjernog i procesnog šuma uzrokovanog sklopnim načinom rada pretvarača. Eksperimentalni rezultati procjene varijabli stanja na uzlaznom pretvaraču snage 450 W napajanim emulatorom gorivnog članka BCS 64-32 pokazuju dobre rezultate procjene, neovisno o režimu rada pretvarača, odnosno radnoj točki određenoj njegovom izlaznom strujom

Design, synthesis, and antimicrobial evaluation of a novel bone-targeting bisphosphonate-ciprofloxacin conjugate for the treatment of osteomyelitis biofilms

Osteomyelitis is a major problem worldwide and is devastating due to the potential for limb-threatening sequelae and mortality. Osteomyelitis pathogens are bone-attached biofilms, making antibiotic delivery challenging. Here we describe a novel osteoadsorptive bisphosphonate-ciprofloxacin conjugate (BV600022), utilizing a “target and release” chemical strategy, which demonstrated a significantly enhanced therapeutic index versus ciprofloxacin for the treatment of osteomyelitis in vivo. In vitro antimicrobial susceptibility testing of the conjugate against common osteomyelitis pathogens revealed an effective bactericidal profile and sustained release of the parent antibiotic over time. Efficacy and safety were demonstrated in an animal model of periprosthetic osteomyelitis, where a single dose of 10 mg/kg (15.6 μmol/kg) conjugate reduced the bacterial load by 99% and demonstrated nearly an order of magnitude greater activity than the parent antibiotic ciprofloxacin (30 mg/kg, 90.6 μmol/kg) given in multiple doses. Conjugates incorporating a bisphosphonate and an antibiotic for bone-targeted delivery to treat osteomyelitis biofilm pathogens constitute a promising approach to providing high bone-antimicrobial potency while minimizing systemic exposure

Effect of mechanical vibrations during transportation on physical and chemical parameters of tomatoes

Określono wpływ drgań na zmiany parametrów fizykochemicznych pomidorów związanych z ich procesem dojrzewania. W pierwszej kolejności dokonano pomiaru drgań występujących podczas rzeczywistego transportu. Następnie skonstruowano stanowisko, które umożliwiało symulację drgań i oznaczano zmiany parametrów fizykochemicznych pomidorów pod wpływem wybranych częstotliwości drgań. Na podstawie przeprowadzonych badan wyznaczono poziomy częstotliwości oraz czas narażenia na drgania skutkujące najwyższymi wartościami badanych parametrów (pH, zawartość ekstraktu) oraz najniższą twardością.The effect of mechanical vibrations on physical and chemical parameters of tomatoes, connected with their maturation process is analyzed. Firstly, vibrations occurring during real road transportation were measured. Then, a vibration simulator was constructed enabling the measurement of physicochemical parameters’ changes in tomatoes under the influence of selected vibration frequencies. The research results allowed one to determine the levels of vibration freąuency and time which leads to the highest values of tested parameters (pH, total soluble solids) and the lowest firmness