Sliding-mode adaptive control of Pioneer 3-DX wheeled mobile robot

Parameter identification scheme and discrete-time adaptive sliding-mode controller applied to Pioneer 3-DX wheeled mobile robot (WMR) are presented in this paper. The dynamical model for mobile robot with one pair of active wheels, time–varying mass and moment of inertia have been used in sliding-mode control. Two closed-loop, on-line parameter estimators have been used in order to achieve robustness against parameter uncertainties (robot mass and moment of inertia). Two sliding-mode adaptive controllers corresponding to angular and position motion have been designed. Closed-loop circular trajectory tracking Pioneer 3-DX real-time control is presented

Dual-mode-locking mechanism for an akinetic dispersive ring cavity swept source

A fast dual-mode-locked akinetic optical swept source in the 1550-nm wavelength band is presented that is tested up to a sweep rate of 797 KHz. It comprises a voltage-controlled oscillator-driven wideband semiconductor optical amplifier (SOA) along with a dispersion compensation fiber, in a ring laser configuration. A Faraday rotating mirror is employed in the cavity as a reflective element in order to achieve better polarization control. By driving the SOA at a high-MHz-frequency value multiple of the resonant frequenc

Copper toxicosis with hemoglobinuric nephrosis in three adult sheep

Acute and, particularly, chronic copper exposures, along with defects in hepatic copper metabolism, altered excretion of copper, and/or nutritional imbalances between copper and other trace elements, can lead to hepatic accumulation of copper and primary copper toxicosis. There is interspecies variation in susceptibility to copper toxicosis, with sheep being the species most likely to develop this condition. The current report is rather unusual in that it describes instances of naturally occurring copper toxicosis with hemolysis and hemoglobinuric nephrosis in 3 adult sheep. In 2 of these sheep, a possible source of excessive dietary copper was investigated but not definitively identified. In the third goat, the etiologic factors associated with the copper toxicosis were not determined. It appears that mature sheep are susceptible to the hemolytic stage of chronic copper toxicosis, which was not observed in a recent, large-scale copper intoxication involving lactating dairy sheep (3, 5, 6, 12). Copper analyses on both kidney samples were necessary to confirm the diagnosis of copper toxicosis in all 3 sheep. All feedstuffs associated with instances of copper toxicosis should be analyzed for iron, molybdenum, sulphur, and zinc as well as copper to determine what nutritional factors are contributing to the pathogenesis of this disease. Consideration also should be given to the ingestion of hepatotoxic plants and other toxic exposures, which could predispose an animal to secondary chronic copper toxicosis (4, 7, 8, 11). It is thought that sheep are predisposed to chronic copper toxicosis because of their reduced biliary and urinary excretion of copper, the distribution of zinc- and copper-binding proteins in the liver, and the relatively small difference between the copper concentrations reported to be adequate for sheep rations (5–10 mg/kg, 7–11 mg/kg, or 10–20 mg/kg on a dry matter basis, depending on the reference) and those dietary copper concentrations considered to be potentially toxic (>15, 20, or 30 mg/kg on a dry matter basis). In contrast, cattle, horses, swine, and poultry tend to be more resistant to copper accumulation and chronic copper toxicosis, with maximum tolerable dry matter concentrations of dietary copper being approximately 50 mg/kg for cattle and horses, 250 mg/kg for swine, and 300–500 mg/kg for poultry. In a previous study, ponies were even reported to tolerate dietary copper concentrations approaching 800 mg/kg for 6 months. However, histopathologic examinations of the kidney were not apparently performed, and it is extremely important to recognize that copper bioavailability and dietary concentrations of molybdenum also play important roles in the pathogenesis of chronic copper toxicosis (9, 10, 13)

Actuator fault reconstruction using FDI system based on sliding mode observers

Interplanetary space missions require spacecraft autonomy in order to fulfill the mission objective. The fault detection and isolation (FDI) system increases the level of autonomy and can ensure the safety of the spacecraft by detecting and isolating potential faults before they become critical. The proposed FDI system is based on an innovative bank of SMOs (sliding mode observers), designed for different fault scenarios cases. The FDI system design aims to detect and isolate actuators and measurement units’ faults used by the satellite control system and considers the nonlinear model of the satellite dynamics. This approach gives the possibility of fault reconstruction based on the information provided by an equivalent injection signal, allowing to reconstruct external perturbances and faults. The SMO chattering phenomenon is avoided by using the pseudo-sliding function, being a linear approximation of the signum function, which gives the possibility of using the equivalent injection signal for fault reconstruction purposes. The proposed fault reconstruction methodology is illustrated by a case study for a 6U Cubesat

1 MHz Akinetic Dispersive Ring Cavity Swept Source at 850 nm

A fast dual mode-locked akinetic optical swept source at 850 nm central wavelength is presented using a dispersive cavity. We demonstrate that single mode fiber can be successfully used as dispersive element to induce mode locking. A first locking condition is imposed by driving the optical gain at a high frequency, to induce mode locking, while a second locking condition involves sweeping at a rate close to resonance value. In this regime, using the same fiber length in the loop, sweeping rates of 0.5 MHz and 1 MHz are demonstrated with proportional reduction in the tuning bandwidth. The axial range of the swept source was evaluated by scanning through the channeled spectrum of a Michelson interferometer

Influence of magnetostatic interactions on first-order-reversal-curve (FORC) diagrams: a micromagnetic approach

Accepted versio

Unusual Canine Distemper Virus Infection in Captive Raccoons (Procyon lotor)

Canine morbillivirus, also known as canine distemper virus (CDV), is the causative agent of canine distemper (CD), which is a serious contagious disease of canines, large felids, and, occasionally, raccoons. This study included seven raccoons from the Timisoara Zoological Garden, Romania. CDV was detected using RT-qPCR on blood samples, but several other exams were also performed—clinical, bacteriological, immunohistochemistry (IHC) and histopathology, toxicological screening, and necropsy—which confirmed CDV infection. Severe digestive disorders (diarrhea and frequent hematemesis) were observed. The necropsy findings included pseudo membranous gastroenteritis, congestion, and pulmonary edema in two raccoons. Immunohistochemistry showed immunolabeled CDV antigenantibodies on the viral nucleocapsid. Histopathology revealed lymphocyte depletion in mesenteric lymphnodes and intranuclear and intracytoplasmic inclusions in the enterocytes of the small intestine. Based on the RT-qPCR assay, laboratory tests, and the lesions observed, it was established that the raccoons were infected with CDV, which was the cause of death in two cases. The results from the necropsy, histology, and immunohistochemistry in the raccoons are comparable with reported CDV lesions in dogs. In conclusion, several exams may be performed to establish the etiology of possible interspecific viral infection, but only very specific exams can identify aCDV infection. Laboratory analyses must be completed by RT-qPCR assay or IHC to establish infection with uncommon viruses in raccoons with high accuracy

Validation of distinct pathogenic patterns in a cohort of membranoproliferative glomerulonephritis patients by cluster analysis

Background: A novel data-driven cluster analysis identified distinct pathogenic patterns in C3-glomerulopathies and immune complex-mediated membranoproliferative glomerulonephritis. Our aim was to replicate these observations in an independent cohort and elucidate disease pathophysiology with detailed analysis of functional complement markers. ----- Methods: A total of 92 patients with clinical, histological, complement and genetic data were involved in the study, and hierarchical cluster analysis was done by Ward method, where four clusters were generated. ----- Results: High levels of sC5b-9 (soluble membrane attack complex), low serum C3 levels and young age at onset (13 years) were characteristic for Cluster 1 with a high prevalence of likely pathogenic variations (LPVs) and C3 nephritic factor, whereas for Cluster 2-which is not reliable because of the small number of cases-strong immunoglobulin G staining, low C3 levels and high prevalence of nephritic syndrome at disease onset were observed. Low plasma sC5b-9 levels, decreased C3 levels and high prevalence of LPV and sclerotic glomeruli were present in Cluster 3, and patients with late onset of the disease (median: 39.5 years) and near-normal C3 levels in Cluster 4. A significant difference was observed in the incidence of end-stage renal disease during follow-up between the different clusters. Patients in Clusters 3-4 had worse renal survival than patients in Clusters 1-2. ----- Conclusions: Our results confirm the main findings of the original cluster analysis and indicate that the observed, distinct pathogenic patterns are replicated in our cohort. Further investigations are necessary to analyse the distinct biological and pathogenic processes in these patient groups