Performance evaluation of a digital electrical impedance tomography system

Performance evaluation of a portable digital multi-frequency electrical impedance tomography system is presented. The instrumentation hardware and image reconstruction are assessed according to a systematic methodology using a practical phantom. The phantom is equipped with eight electrodes in a ring configuration and a sinusoidal current of constant amplitude is injected using an adjacent current injection protocol. Artificial anomalies are introduced as inhomogeneity targets and the boundary potential data is collected. The images are reconstructed from the boundary data using Comsol Multiphysics and Matlab. Signal to noise ratio (SNR) and accuracy of the measurements are calculated. The limits of detectability and distinguishability of contrasts are measured from the collected potential data set for single and double inhomogeneities. The conductivity of the targets is successfully reconstructed from the potential data measurements. The detectability value is found to be high when a single target is close to the electrodes, while the values are less for the target in the centre. Also, the value of distinguishability increases when the targets move further away from each other

Effects of secondary compounds from cactus and acacias trees on rumen microbial profile changes performed by Real-Time PCR

Plant rich secondary compounds had antimicrobial effects by acting against different rumen microbial populations. The current study investigated the influence of spineless cactus (Opuntia ficus indica f. inermis), Acacia nilotica and A. saligna on rumen microbial fermentation, using in vitro gas production technique, and microbial population profile changes, using a molecular-based technique (Real-Time PCR). The acacias and Opuntia reduced significantly total gas production (p<0.01), rumen CH4 production (p?0.01) and ammonia concentration (p<0.001). At 24h of incubation, Fungi population was 0.30- and 0.03 -fold reduced with A.nilotica and Opuntia as compared to 0h, but 2-and 1.24- fold higher with A.cyanophylla .Increases in the abundance of F.succinogenes were observed in all substrates; however, the tanniferous plants and Opuntia reduced the relative abundance of R.flavefaciens. Methanogenic population was increased with all substrates, except for Opuntia (0. 90- fold lower than the control). There was a significant reduction (p<0.05) in rumen protozoa count with A.cyanophylla, Opuntia and A.nilotica (3.68; 5.59 and 5.34 times, respectively). Results suggested that tannin sources from A.nilotica and A.cyanophylla had an indirect effect on methanogenesis. This study showed an antimicrobial activity of oxalates content of O. ficus indica

MCDHF calculations of isotope shifts in neutral antimony

Ab initio multiconfiguration Dirac–Hartree–Fock (MCDHF) calculations have been carried out in order to determine the isotope shift (IS) electronic parameters of transitions belonging to electric dipole (E1) transition arrays 5s25p3−5s25p26s, 5s25p26s−5s25p26p and 5s25p26s−5s25p27p in neutral antimony, Sb I. In a correlation model limited to single and double excitations from the valence shells, these parameters, combined with the changes in mean-square nuclear charge radius δ⟨r2⟩123,121 compiled by Angeli and Marinova [3] produce isotope shifts values in good agreement with the most recent measurements by high-resolution emission and optogalvanic absorption spectroscopy of Sobolewski et al. [5] but not with the old measurements of Buchholz et al. [4] for 5p3−5p26s. However, our analysis does not allow to reject the latter due to the large uncertainty affecting δ⟨r2⟩123,121, i.e. 0.072 ± 0.048 fm2 [3]. This shows the need of a more accurate determination of this nuclear parameter. Although improving excitation energies, the inclusion of core-valence correlation limited to one hole in the 4d core subshell destroyed the theory-experiment agreement on the IS parameters. © 2018 Elsevier LtdInteruniversity Attraction Poles Programm

New OSTBC for Blind Channel Estimation and Tracking in MIMO-OFDM Systems, Journal of Telecommunications and Information Technology, 2019, nr 3

Applying orthogonal space time block coding (OSTBC) to multiple-input multiple-output (MIMO) systems helps reduce receiver complexity. However, this approach has been applied only to flat fading channels, as when the channel is a frequency selective fading MIMO channel, OSTBC cannot be used directly since its orthogonal propriety may be lost. Furthermore, the MIMO channel is not always known. To deal with this problem, many techniques were proposed to estimate the channel using a training sequence. Unfortunately, these techniques reduce the useful spectral bandwidth. This paper proposes OSTBC for blind channel estimation and data detection in the case of a MIMO frequency selective channel. The aim of this new OSTBC is twofold: to solve the ambiguity of channel estimation and to reduce the complexity of the detector. By exploiting the well-known technique of orthogonal frequency division multiplexing (OFDM), the frequency selective fading MIMO channel is split into a set of flat fading subchannels. Moreover, to accommodate the fact that a MIMO channel can be time varying, the steady state Kalman channel estimator (SS-KCE) is extended to track the channel’s fast variations. The performance of the proposed blind algorithm is related by the adequate choice of the number of subcarriers and it is compared with other existing approaches by means of Monte Carlo simulations

Geosynthetic capillary barriers: current state of knowledge

ABSTRACT: This paper provides theoretical background, laboratory data and full-scale measurements useful in understanding the interaction between soils and geosynthetics under unsaturated conditions. It also includes an evaluation of the current state of knowledge regarding the hydraulic properties of porous geosynthetics under unsaturated conditions relevant for geosynthetic capillary barrier design. These properties include the water retention curve and the hydraulic conductivity function. In addition, the mechanisms involved in the development of capillary barriers are evaluated to explain the storage of water at the interface between materials with contrasting hydraulic conductivity (e.g. a fine-grained soil and a nonwoven geotextile). Finally, specific applications are presented to illustrate new opportunities and applications that may result from a better understanding of the unsaturated hydraulic properties of geosynthetics. Experimental data are provided illustrating that geosynthetic capillary barriers are superior to soil-only capillary barriers. Based on this observation, it is emphasized that no capillary barrier should be designed without consideration of the enhanced performance offered by the inclusion of nonwoven geotextiles under the fine-grained soil component of the cover

Psychometric Properties of Smartphone Addiction Questionnaire (SPAQ) among Sultan Qaboos University Undergraduate Students

The aim of this study was to identify the psychometric properties of a smartphone addiction questionnaire. It explored the structure of the questionnaire: smartphone usage, the level of addiction to smartphones' different activities and applications, and the level of smartphones' addiction symptoms appearance. The dimensional structure of the questionnaire was investigated with a sample of 140 SQU undergraduates (37.1% males and 62.9% females). Based on the factor analysis results, the questionnaire consisted of five factors: disregard of harmful consequences, preoccupation, inability to control craving, productivity loss and feeling anxious and lost. The internal consistency and concurrent validity of SPAQ were verified (Cronbach's alpha= 0.76). SPAQ and its factors were significantly correlated with smartphone addiction scale (SAS). The reliability of SPAQ has been tested using test-re-test method and revealed a significant correlation of 0.67 between the two applications

The Effect of the Stationary Phase on Resolution in the HPLC-Based Separation of Racemic Mixtures Using Vancomycin as a Chiral Selector: A Case Study with Profen Nonsteroidal Anti-Inflammatory Drugs

\ua9 2023 by the authors.Chiral resolution is a technique of choice, making it possible to obtain asymmetric and enantiomerically pure compounds from a racemic mixture. This study investigated the behavior of vancomycin when used as a chiral additive in high-performance liquid chromatography (HPLC) to separate enantiomers of nonsteroidal anti-inflammatory drugs (NSAIDs), including ketoprofen, ibuprofen, flurbiprofen, and naproxen enantiomeric impurities. We compared two achiral stationary phases (C18 and NH2) to assess the impact of mobile phase composition and stationary phase on the vancomycin retention time in the racemic resolution of drug enantiomers. Our results demonstrated the successful enantioseparation of all drugs using vancomycin in the mobile phase (phosphate buffer 0.05 M/2-propanol, 50/50) with an NH2 column. This enhanced separation on the NH2 column resulted from the chromatography system’s efficiency and vancomycin dimers’ stereoselective interaction on the NH2 surface. This study underscores the importance of stationary phase selection in the chiral resolution of NSAIDs with vancomycin as a chiral additive. It offers valuable insights for future research and development of NSAID chiral separation methods, highlighting potential vancomycin applications in this context