Semi-active stabilisation of a pipe conveying fluid using eddy-current dampers: state-feedback control design,experimental validation

An application of electromagnetic devices of the motional type (i.e. eddy-current dampers) to improve the dynamic stability of a cantilever pipe discharging fluid is proposed. When the flow velocity reaches a critical value, this system loses stability through the flutter. A contactless damping device is used. This actuator is made of a conducting plate attached to the pipe that moves together with it within the perpendicular magnetic field that is generated by the controlled electromagnets. During the motion the eddy currents in the plate and a resultant drag force of a viscous character are generated. First, an optimal control problem that aims to stabilise the system with the optimal rate of decrease of the system’s energy is posed and solved. Then a state-feedback parametrization of the obtained optimal control, which can be used in a closed-loop scheme is proposed. The effectiveness of the designed optimal controller is validated by making a comparison with the corresponding passive solutions on the specially designed and constructed experimental test stand of a pipe conveying air.

     

Kinetics and Characterization of Degradation Products of Dihydralazine and Hydrochlorothiazide in Binary Mixture by HPLC-UV,LC-DAD and LC–MS Methods

Dihydralazine and hydrochlorothiazide were stored at high temperature and humidity, under UV/Vis light and different pH, as individual drugs and the mixture. Then, a sensitive and selective HPLC-UV method was developed for simultaneous determination of dihydralazine and hydrochlorothiazide in presence of their degradation products. Finally, the degradation products were characterized through LC-DAD and LC–MS methods. Dihydralazine was sensitive to high temperature and humidity, UV/Vis light and pH?≥?7. At the same time, it was resistant to acidic conditions. Hydrochlorothiazide was sensitive to high temperature and humidity, UV/Vis light and changes in pH. Its highest level of degradation was observed in 1 M HCl. Degradation of the drugs was higher when they were stressed in the mixture. In the case of dihydralazine, the percentage degradation was 5–15 times higher. What is more, dihydralazine became sensitive to acidic conditions. Hydrochlorothiazide was shown to be more sensitive to UV/Vis light and pH?>?4. Degradation of dihydralazine and hydrochlorothiazide followed first-order kinetics. The quickest degradation of dihydralazine was found to be in 1 M NaOH while of hydrochlorothiazide was in 1 M HCl (individual hydrochlorothiazide) or at pH 7–10 (hydrochlorothiazide in the mixture). A number of new degradation products were detected and some of them were identified by our LC-DAD and LC–MS methods. In the stressed individual samples, (phenylmethyl)hydrazine and 1,2,4-benzothiadiazine-7-sulfonamide 1,1-dioxide were observed for the first time. Interactions between dihydralazine and hydrochlorothiazide in the mixture were confirmed by additional degradation products, e.g., 2H-1,2,4-benzothiadiazine-7-sulfonamide 1,1,4-trioxide.     

Stabilité analytique et convergence locale de translatées en dynamique homogène S-arithmétique

We present the main result of Richard and Zamojski [14] concerning, in homogeneous dynamics, the general problem of the dynamics of sequences of translates of a certain measure in a space of S-arithmetic lattices.     

Embedding Banach spaces into the space of bounded functions with countable support

We prove that a WLD subspace of the space consisting of all bounded, countably supported functions on a set Γ embeds isomorphically into if and only if it does not contain isometric copies of . Moreover, a subspace of is constructed that has an unconditional basis, does not embed into , and whose every weakly compact subset is separable (in particular, it cannot contain any isomorphic copies of ).     

Erratum to: “Comparative studies of Pd, Ru, Ni, Cu/ZnAl2O4 catalysts for the water gas shift reaction”

The original version of the article was published in Cent. Eur. J. Chem. 11(6) (2013) pp. 912–919. Unfortunately, the original version of this article contains a mistake in the Acknowledgement section. It should be written as “Partially financed from grant number 0680/B/H03/2011/40 and gratefully acknowledged. Pawe? Mierczyński is a participant of START Programme.”     

Thermographic imaging as alternative method in allergy diagnosis

Allergen sensitization is being diagnosed by commonly available methods in clinical practice—skin prick tests (SPTs) and specific immunoglobulin E test (sIgE). Recently, a new thermographic (TH) method for the assessment of SPT was developed, and it was demonstrated that the TH measurements of forearm temperature distribution during SPT, supported by a mathematical model, offer a new quantification method of allergen-induced skin reactions. The aim of this study is a comprehensive comparison of the TH method with SPT and sIgE techniques. The studies were performed for a group of 51 patients. The SPT and sIgE examinations were done in a routine way. For TH analyses, set of thermograms of both forearms were acquired after prick and analyzed with the use of developed software. All results were converted into categorized scale for comparison. The collected results indicate high correlation coefficients between methods equal to 0.76–0.99. Sensitivity and accuracy of TH assessment in respect of both SPT and sIgE methods is at good level (0.72–0.93). Acceptable level of specificity 0.60–0.88 was also achieved for most allergic responses. Excellent agreement between SPT and sIgE methods was observed which makes the TH assessment competitive. Due to higher precision and sensitivity of digital infrared technology, possibility of making error in diagnosis is significantly reduced. Additional advantage of the TH method relies on an estimation of the skin reactivity which allows highlighting the hypersensitivity patients and automatic correction of the diagnosis.     

Fractional electrical model for modified bismuth oxide

Modified bismuth oxide (Bi₂O₃) is of great importance to fuel cells and oxide varistors. The electrical parameters of Bi₂O₃ vary with its modifying components as well as with its aging temperature. This paper presents an analysis of impedance test results carried out to find an equivalent electric model and the relationship between the model's elements to various additives used to modify Bi₂O₃ and to changes in aging temperature. The proposed model was tested via computer simulation and the model parameters correlated to individual modifiers.     

SUBSTITUENT EFFECTS OF PHOSPHORUS-CONTAINING GROUPS. THE ELECTRONIC EFFECTS IN ANILIDES AND PHENYL ESTERS

Abstract

¹³C NMR shielding parameters have been determined for the N-phosphorylated aniline and O-phosphorylated phenol derivatives, Ph–Y–P(O)Z₂ (Y=NH, O), and for their complexes with titanium tetrachloride. Inductive and resonance substituent constants were calculated using the dsp approach for the neutral and charged substituents. The results are compared with those for the corresponding neutral and charged acetyl derivatives. Shielding effects and substituent constants are discussed in terms of the interactions of the lone pair at Y with the aromatic ring and with the acyl center. It is concluded that no significant p _π-d _π back-donation from Y to the phosphorus atom operates in the systems studied.