ABSTRACT
The present study suggests a disturbance estimator design method for application to a recently published, two-degree-of-freedom, control scheme for open-loop, unstable processes with time delay. A simple PID controller cascaded with a lead-lag filter replaces the high-order disturbance estimator for enhanced performance. A new analytical method on the basis of the IMC design principle, featuring only one user-defined tuning parameter, is developed for the design of the disturbance estimator. Several illustrative examples taken from previous works are included to demonstrate the superiority of the proposed disturbance estimator. The results confirm the superior performance of the proposed disturbance estimator in both nominal and robust cases. The proposed method also offers several important advantages for industrial process engineers: it covers several classes of unstable process with time delay in a unified manner, and is simple and easy to design and tune.
Subject(s)
Algorithms , Feedback , Models, Theoretical , Nonlinear Dynamics , Computer Simulation , Numerical Analysis, Computer-Assisted , Time FactorsABSTRACT
High-density single-crystalline Zn2SnO4 nanowires have been successfully synthesized by using a simple thermal evaporation method by heating a mixture of ZnO and SnO2 nano powders. The products in general contain various geometries of wires, with an average diameter of 80-100 nm. These nanowires are ultra-long, up to 100 microns. The transmission electron microscopy study showed that these nanowires exhibited zigzag twinned geometry, and grow along the (111) direction. Low-temperature photoluminescence properties of the nanowires were measured, showing a strong green emission band at about 515 nm and a weak peak corresponding to UV emission at about 378 nm, which have not been reported before.
Subject(s)
Luminescent Measurements/methods , Nanowires/chemistry , Photochemistry/methods , Tin Compounds/chemistry , Zinc Oxide/chemistry , Cold Temperature , Hot Temperature , Luminescence , Materials Testing , Microscopy, Electron, Scanning , Microscopy, Electron, Transmission , Nanowires/radiation effects , Nanowires/ultrastructure , Phase Transition , Powders , Spectrophotometry , Spectrum Analysis, Raman , X-Ray Diffraction , Zinc Compounds/chemistryABSTRACT
Recent studies have shown a strong correlation between grain growth and chemical ordering in chemically synthesized FePt nanoparticles. In order to study this effect, we have prepared a series of samples in which 3.5 nm FePt nanoparticles are dispersed in a matrix of Cu nanoparticles. The samples were annealed at 600 degrees C and at 800 degrees C. Grain size was determined by XRD Scherrer analysis and time-dependent remanent coercivity measurements were made to determine the intrinsic remanent coercivity, Hcr0. For samples annealed at 600 degrees C, Hcr0 increases strongly with grain size up to approximately 5 nm and increases weakly with additional grain growth. By contrast, after annealing at 800 degrees C, Hcr0 appears nearly independent of grain size. The results suggest that isolated 3.5 nm FePt nanoparticles can be weakly ordered when annealed at 600 degrees C and sintering is necessary for significant chemical ordering.
Subject(s)
Copper/chemistry , Crystallization/methods , Hot Temperature , Iron/chemistry , Lead/chemistry , Nanostructures/chemistry , Nanostructures/ultrastructure , Nanotechnology/methods , Macromolecular Substances/chemistry , Materials Testing , Molecular Conformation , Particle Size , Surface PropertiesABSTRACT
So far known Andrographis paniculata Nees (AP) is a hepatoprotective, antiplatelet and antithrombotic drug. In this experiment its hypoglycaemic effect has been tried in various way. Water extract of AP 10 mg/kg body weight can prevent induction of hyperglycaemia significantly (P < 0.001) induced by oral administration of glucose 2 mg/kg body weight. But any how failed to do so in adrenaline induced hyperglycaemia. It also failed to demonstrate any "fasting blood sugar lowering effect" upon chronic administration (6 weeks) of AP. So probably AP prevents glucose absorption from gut. Whole experiment was done on rabbits.
Subject(s)
Anticoagulants/pharmacology , Hypoglycemia/chemically induced , Plants, Medicinal , Platelet Aggregation Inhibitors/pharmacology , Animals , Blood Glucose/analysis , Female , Male , RabbitsABSTRACT
Six weeks old male and female mice belonging to Wister strain were put on diets supplemented to the extent of 0.75% by the powdered stem of A. peniculata Nees for one, two, three and four weeks and the effect on fertility and gestational period was observed. Significant reduction in fertility was observed after three and four weeks of feeding in the group containing the treated males and the untreated females. In the same group the gestation period was also prolonged after four weeks of feeding. There was virtually no change in fertility and gestational period in the treated females and the untreated males during any stage of the experiment.
PIP: 6-week-old male and female Wistar mice were given diets supplemented with .75% powdered stem of A. peniculata Nees for 1, 2, 3, and 4 weeks to study the effect of the medicinal plant on fertility and gestation. In the 1- and 2-week groups, the medication did not produce any appreciable change in fertility or in the period of gestation. However, significantly reduced fertility was found in the males in the 3-week group. No appreciable change in the females or the untreated animals was found in the 3-week groups. When the medication was given for 4 weeks, a significantly prolonged period of gestation was found among the male-treated subgroup. It is concluded that the drug somehow affects the males with no apparent effect on the females; one explanation is that the drug lowered the male libido, explaining the prolonged gestational period in the 4-week group because gestational age was measured by the date the males were placed in cages with females and with lowered libido mating may not have occurred immediately.
