Backlash is one of the most important non-linearities that limit the performance of speed and position control in industrial, robotics, automotive, automation and other applications. The control of systems with backlash has been the subject of study since the 1940s. This survey reveals that surprisingly few control innovations have been presented since the early path breaking papers that introduced the describing function analysis of systems with backlash. Promising developments are however taking place using adaptive and non-linear control strategies. 相似文献
We report on two patients with sulbactam/ampicillin (SBT/ABPC)-induced pneumonitis. Both patients were being treated with SBT/ABPC for respiratory-tract infections. Following the initiation of SBT/ABPC chemotherapy, however, chest X-ray films showed a shift of shadow in patient 1 and new pulmonary infiltration shadows in patient 2. Bronchoalveolar lavage fluid (BALF) findings showed a marked increase in the total cell count and percentage of eosinophils in patient 1 and of lymphocytes in patient 2. The results of lymphocyte stimulation tests were SBT/ABPC positive for both patients. SBT/ABPC therapy was therefore discontinued and corticosteroid therapy started. Both patients were subsequently relieved of their symptoms demonstrated significantly lower and pulmonary infiltrate levels. Based on these findings, both patients were given a diagnosis of SBT/ABPC-induced pneumonitis. It has been widely reported that CD 4/CD 8 ratio in BALF decreases in cases of drug-induced pneumonitis. However, some reports have cited increase in the CD 4/CD 8 ratio. In our two patients as well, the CD 4/CD 8 ratio increased. These results, together with the findings from several other case reports, indicate that the CD 4/CD 8 ratio may not be good basis for diagnosing drug-induced pneumonitis. Recently, the incidence of drug-induced pneumonitis has been rising. To our knowledge this is the first report documenting cases of SBT/ABPC-induced pneumonitis. 相似文献
Corrosion fatigue tests were carried out on extruded AZ31 (3% Al, 1% Zn, 0.3% Mn, Mg—the rest), AM50 (5% Al, 0.4% Mn, Mg—the rest) and ZK60 (5% Zn, 0.5% Zr, Mg—the rest) Mg alloys in air, NaCl-based and borate solutions. Nsol/Nair ratios (the relative fatigue life) were used for the analysis of the corrosion fatigue behavior of Mg alloys in various environments, where Nsol and Nair are the numbers of cycles to failure in the solution and in air, respectively. Extruded ZK60 alloy reveals very high fatigue and corrosion fatigue properties in comparison with other alloys. However, it has the lowest relative fatigue life (Nsol/Nair 10−3–10−2) or the highest sensitivity to the action of NaCl-based solutions in comparison with that of AM50 and AZ31 alloys (Nsol/Nair 10−2–10−1). Under the same stress, the corrosion fatigue life of extruded alloys is significantly longer than that of die-cast alloys (Nsol for extruded AM50 in NaCl is two to three times longer than that of die-cast AM50). 相似文献
This paper develops adaptive state feedback control schemes for a class of linear systems with state delay in the presence of unknown actuator failures. The main contributions of this paper are the development of two controller parametrizations which attempt to anticipate the future states, the introduction of an appropriate Lyapunov–Krasovskii type functional to design the new class of adaptation algorithms, and a stability proof. 相似文献
Dense, single-phase β-sialon ceramics were sintered at 1700°C and 200 MPa using the glass-encapsulated hot isostatic pressing technique. The materials were very hard, 1500 to 1700 kg / mm2 (98 N load), but were fairly brittle, with an indention fracture toughness of about 3 MPa · m1/2. The addition of 1 wt% Y2O3 before sintering had a positive effect on the toughness, especially at the low x compositions of Si3-xAlxOxN4-x, where KIC∼4 MPa · m1/2. 相似文献
Combustion of CO, ethyl acetate and ethanol was studied over CuOx/Al2O3, CuOx–CeO2/Al2O3, CuMn2O4/Al2O3 and Mn2O3/Al2O3 catalysts. It was found that modification of the alumina with ceria before subsequent copper oxide deposition increases the activity for combustion of CO substantially, but the effect of ceria was small on the combustion of ethyl acetate and ethanol. The activity increases with the CuOx loading until crystalline CuO particles are formed, which contribute little to the total active surface. The CuOx–CeO2/Al2O3 catalyst is more active than the CuMn2O4/Al2O3 catalyst for the oxidation of CO but the CuMn2O4/Al2O3 catalyst is more active for the combustion of ethyl acetate and ethanol.
Thermal ageing and water vapour in the feed caused a modest decrease in activity and did not affect the CuOx–CeO2/Al2O3 and CuMn2O4/Al2O3 catalysts differently. In addition, no difference in intermediates formed over the two catalysts was observed.
Characterisation with XRD, FT-Raman and TPR indicates that the copper oxide is present as a copper aluminate surface phase on alumina at low loading. At high loading, bulk CuO crystallites are present as well. Modification of the alumina with ceria before the copper oxide deposition gives well dispersed copper oxide species and bulk CuO crystallites associated to the ceria, in addition to the two copper oxide species on the bare alumina. The distribution of copper species depends on the ceria and copper oxide loading. The alumina supported copper manganese oxide and manganese oxide catalysts consist mainly of crystalline CuMn2O4 and Mn2O3, respectively, on Al2O3. 相似文献
The effects of intranasal syringing with 5% zinc sulfate were assessed in rats trained in a wind-tunnel olfactometer to detect the presence of an odor or to discriminate odors of graded intensities. The syringing produced a severe but brief interference in olfactory performance. Full recovery of detection performance occurred within 72 hr after treatment. Initial recovery of odor intensity discrimination occurred in 2-8 days and full recovery within 8-10 days. These results suggest that intranasal syringing with ZnSO4 is not an adequate control for the effects of anosmia produced by olfactory bulbectomy. 相似文献