SPICE application in the study of the behaviour of multi-state systems described by Markov models

This paper shows the applicability of the SPICE circuit analysis computer program for studying the behaviour of multi-state desribed by Markov models. Two samples are considered and the results are compared with those obtained by the Laplace transform and the flow graph methods. Agreement between the three techniques is excellent.     

MATCHING OF SEPARATELY EXCITED DC MOTORS TO PHOTOVOLTAIC GENERATORS FOR MAXIMUM POWER OUTPUT

This paper addresses the matching of separately excited dc motors to photovoltaic generators (PVG) for maximum power output. The dc motor is used to drive a centrifugal water pump. A PVG is a nonlinear device having insolation dependent I–V (current–voltage) characteristic, and hence a natural mismatch exists between the motor loads and the PVG. Therefore, considering the high initial cost of PVG, it is of vital importance to develop an appropriate matching process, to utilize PVG efficiently. In this article a procedure is developed to express the field current of the motor directly in terms of the maximum power point current and voltage of the PVG. It is shown that by adjusting the field current according to the developed relation, the motor is forced to follow the maximum power trajectory of the PVG, i.e. the input power of the motor is always equal to the maximum output power of the PVG at any available solar insolation. The effect of temperature on the I–V characteristic of the PVG is neglected at this stage. Finally a general expression is proposed relating the optimum field current directly to the available insolation level, which may be used as base for best matching.     

The visuo-motor pathway in the local circuit of the rat superior colliculus

Intrinsic circuit of the superior colliculus (SC), in particular the pathway from the optic tract (OT) to neurons in the intermediate layer (SGI), was investigated by whole-cell patch-clamp recording in slice preparations obtained from 17- to 24-d-old rats. Stimulation of the OT induced monosynaptic EPSPs in neurons in the superficial gray layer (SGS) and the optic layer (SO), and disynaptic or polysynaptic EPSPs in a majority of SGI neurons. Stimulation of the SGS induced monosynaptic or oligosynaptic EPSPs in the SGI neurons. Both the monosynaptic EPSPs induced in the SGS/SO neurons by stimulation of the OT and those induced in the SGI neurons by stimulation of the SGS were mediated by AMPA- and NMDA-type glutamate receptors. Thus, we have clarified the existence of the glutamatergic excitatory pathway from the OT to the SGI neurons via SGS and SO neurons. The EPSPs in the SGI neurons induced by stimulation of the OT or SGS were remarkably enhanced by bicuculline, suggesting that the signal transmission in this pathway is under strong suppression by the GABAergic system.     

Stress intensity factor calculation for a modified round bend bar by 3-D finite element analysis

Stress intensity factors were calculated for a modified round bend bar (MRBB) using 3-D finite element analysis. The results were compared with published solutions for a rectangular and round bend bars. The stress intensity values for the MRBB are between those for the two other geometries as expected. The stress intensity solutions were non-dimensionalized utilizing limit solution for short and long cracks.     

Assessment of evolutionary algorithms in predicting non-deposition sediment transport

In this article, the densimetric Froude number of the flow is estimated using the parameters of volumetric sediment concentration (C_V), the relative depth of flow (d/R), dimensionless particle number (D_gr) and the overall sediment friction factor (λ_s). The particle swarm optimization (PSO) and imperialist competitive algorithms (ICA) were used to estimate the densimetric Froude number. To study the effects of sediment transport parameters on the densimetric Froude number, six different models are presented. The PSO algorithm with root mean square error (RMSE) = 0.014 and mean absolute percentage error (MAPE) = 5.1% present the results with a relatively good accuracy. The accuracy of the results presented for the selected model by the ICA algorithm is also in the form of RMSE = 0.007 and MAPE = 5.6%. Although both algorithms return good results in estimating the densimetric Froude number for the selected model, it should be mentioned that for all the six presented models ICA returns better results than PSO.     

Current and future interventions for improving poultry health and poultry food safety and security: A comprehensive review

Poultry is thriving across the globe. Chicken meat is the most preferred poultry worldwide, and its popularity is increasing. However, poultry also threatens human hygiene, especially as a fomite of infectious diseases caused by the major foodborne pathogens (Campylobacter, Salmonella, and Listeria). Preventing pathogenic bacterial biofilm is crucial in the chicken industry due to increasing food safety hazards caused by recurring contamination and the rapid degradation of meat, as well as the increased resistance of bacteria to cleaning and disinfection procedures commonly used in chicken processing plants. To address this, various innovative and promising strategies to combat bacterial resistance and biofilm are emerging to improve food safety and quality and extend shelf-life. In particular, natural compounds are attractive because of their potential antimicrobial activities. Natural compounds can also boost the immune system and improve poultry health and performance. In addition to phytochemicals, bacteriophages, nanoparticles, coatings, enzymes, and probiotics represent unique and environmentally friendly strategies in the poultry processing industry to prevent foodborne pathogens from reaching the consumer. Lactoferrin, bacteriocin, antimicrobial peptides, cell-free supernatants, and biosurfactants are also of considerable interest for their prospective application as natural antimicrobials for improving the safety of raw poultry meat. This review aims to describe the feasibility of these proposed strategies and provide an overview of recent published evidences to control microorganisms in the poultry industry, considering the human health, food safety, and economic aspects of poultry production.     

Fault detection and location in gears by the smoothed instantaneous power spectrum distribution

Time–frequency methods are effective tools for analysing diagnostics signals and have been widely used to describe machine condition. This paper introduces a time–frequency distribution, called the smoothed instantaneous power spectrum (SIPS) distribution, and demonstrates its use in the detection and location of local tooth defects in gears. The SIPS distribution is derived from the frequency domain definition of the instantaneous power spectrum (IPS) distribution, but has the added advantage that provides a considerable reduction in the ringing effect of the IPS transform, which results in a smoother and clearer time–frequency representation. A simulated gear vibration signal is used to show the capabilities of the proposed method over the IPS distribution and spectrogram. Healthy and faulty vibration signals monitored from a gear test rig are analysed, the results of which show that a local gear tooth defect can clearly be detected by the SIPS distribution.     

Axial view inductively coupled plasma optical emission spectrometry for monitoring tin concentration in canned tomato sauce samples

In this study it was evaluated the variation of tin concentration in function of storage time in canned food samples by using an axial view inductively coupled plasma optical emission spectrometry (AX ICP OES). The effect of various parameters of the ICP OES, such as analytical lines, sample introduction systems and interferences were investigated. Eight emission lines for tin were tested, but only 283.998 nm line was found to be robust enough with respect to interferences and sensitivity, presenting a limit of quantification of 0.094 mg kg⁻¹. A concentric nebuliser combined with a cyclonic chamber has shown better sensitivity than a V-groove nebuliser. Tin was determined in canned tomato sauce stored at room temperature (20.0 ± 1.8 °C) for 0, 30, 60, 90, 120 and 150 days. After 150 days, tin contents increased in the 43-91% range. Despite an increase of almost 100% for one sample, tin contents are well below the maximum level allowed by Agência Nacional de Vigilância Sanitária (ANVISA) regulation of 250 mg kg⁻¹.     

Effects of powder size and metallic bonding layer on corrosion behaviour of plasma-sprayed Al2O3-13% TiO2 coated mild steel in fresh tropical seawater

This study focuses on the effects of powder size and Ni–Al bonding layer on the electrochemical behaviour of plasma-sprayed Al₂O₃-13% TiO₂ coating in fresh tropical seawater. The presence of the metallic bonding layer reduces the coating porosity and increases the surface roughness for both microparticle and nanoparticle coatings. The nanoparticle exhibits better corrosion rate of 1.9×10⁻⁶ mmpy compared to the microparticle coating, with a corrosion rate of 3.05×10⁻⁶ mmpy. However, the presence of the metallic bonding layer increases the corrosion rate for both micro and nanoparticle coatings. The corrosion mechanism for the coating with and without the metallic bonding layer is discussed in detail.