Robust adaptive finite-time stabilization control for a class of nonlinear switched systems based on finite-time disturbance observer

The problem of adaptive global finite-time stabilization control for a class of nonlinear switched systems in the presence of external perturbations and arbitrary switchings has been addressed in this research study. The proposed scheme has been designed based on a finite-time estimation technique in which during the control procedure, unknown imposed perturbations are accurately estimated by means of the designed finite-time disturbance observer (FTDO). Due to the exact estimation of the external disturbances within a given finite time, the encountered complications and adversities from loss of information in the Lyapunov parameter estimation (LPE) methods have been solved which are caused by the persistent switchings in the system. Furthermore, a new solution for the problem of chattering phenomenon in nonlinear switched systems has been presented by utilizing the designed FTDO, which can counteract the malfunctioning responses of the system caused by external disturbances and unmodeled dynamics. In this paper, an acknowledged class of nonlinear switched systems has been taken into account which is in the general form of canonical structure. In addition, the established design strategy is formulated for the control of perturbed nonlinear switched systems with one and only input and assures that the system states through the finite-time convergence characteristic, reach the equilibrium point of origin. Finally, numerical simulations are carried out on a mass-spring-damper (MSD) dynamical system to indicate advantages and superior efficiency of the suggested method.     

Protective effect of ascorbic acid against oxidative damage induced by hydrogen peroxide in cultured human peripheral blood lymphocytes

Hydrogen peroxide is one of the reactive oxygen species for cellular injury. It is overproduced during oxidative stress and is known to damage proteins, nucleic acids and cell membranes. The present study was aimed to study the protective effect of ascorbic acid against the toxic doses of hydrogen peroxide using lipid peroxidation and cytokinesis blocked micronucleus assay. Hydrogen peroxide was studied at 50, 100 and 200μM and was found to increase a dose dependent increase in lipid peroxidation and micronuclei frequency. The treatment of 100 and 200μM of hydrogen peroxide separately along with 20, 40 and 80μM of ascorbic acid showed a dose dependent decrease in the lipid peroxidation and micronuclei frequency. The results suggest a protective effect of ascorbic acid against the hydrogen peroxide induced oxidative damage in cultured human peripheral blood lymphocytes.     

Attenuation of oxidative stress in streptozotocin-induced diabetic rats by <Emphasis Type="Italic">Eucalyptus globulus</Emphasis>

In traditional medicine, Eucalyptus globulus (eucalyptus) was used for the treatment of diabetes mellitus. Hyperglycemia in diabetes has been associated with increased formation of reactive oxygen species (ROS) and oxidative damage to tissue compounds. The aim of this study was to evaluate the effects of eucalyptus in the diet (20 g/Kg) and drinking water (2.5 g/L) on lipid peroxidation, protein oxidation and antioxidant power in plasma and liver homogenate, as well as glycated-Hb (HbA_1C) of blood in streptozotocin-induced diabetic rats for a period of 4 weeks. Diabetes induced in rats by a single intraperitoneal injection of streptozotocin (STZ, 65 mg/Kg). At the end of the treatment period, the level of plasma glucose, plasma and liver malondialdehyde (MDA, the main product of lipid peroxidation), protein carbonyl (PC, one of the protein oxidation products) and HbA_1C increased and ferric reducing antioxidant power (FRAP) decreased in diabetic rats compared to normal rats. Eucalyptus administration for 4 weeks caused a significant decrease in the plasma glucose levels, plasma and liver MDA, PC and HbA_1C, also a concomitant increase in the levels of FRAP in diabetic treated rats. In conclusion, the present study showed that eucalyptus posses antioxidant activities. Eucalyptus probably restores antioxidant power, due to the improved hyperglycemia in streptozotocin-induced diabetic rats.     

Changing Attitudes to University Mathematics Through Problem Solving

University mathematics is often presented in a formal way that causes many students to cope by memorising what they perceive as a fixed body of knowledge rather than learning to think for themselves. This research studies the effects on students' attitudes of a course encouraging co-operative problem-solving and reflection on the thinking activities involved. The attitudinal questionnaire was shown to the students' teachers who were asked to specify the attitudes they expect from their students and the attitudes they prefer. This was used to give a ‘desired direction of change’ from expected to preferred. Before the course, half the students responded that university mathematics did not make sense. A majority declared negative attitudes such as anxiety, fear of new problems and lack of confidence. During the problem-solving course the changes were almost all in the desired direction. During the following six months of standard mathematics lecturing, almost all changes were in the opposite direction. This revised version was published online in July 2006 with corrections to the Cover Date.     

Yaffa: a school of their choice?

This article is a product of in‐depth research in Yaffa, The Arab Democratic School that was carried out in 2004/05, as part of a study on alternative Arab education in Israel. Its aim, beyond telling the story of Yaffa, is to explicate the motivations that underlay this initiative, and to examine parental choice amongst the disadvantaged. We ask how the Arabs’ parental choice is affected by their (marginalised) social location, by how far they are from the dominant culture, and by their (in)capacity to make a difference. Apparently, to make a choice is a multidimensional act, reflecting the Palestinian citizens’ resistance to their marginalisation and unwillingness to be subjugated through non‐democratic educational perceptions. Their positionality resonates in Yaffa, as an act of intervention, and their search for an alternative reality where democratic education is not and cannot be separated from the Palestinian citizens’ need to imagine themselves as Arabs.     

A new fabrication technique to form complex polymethylmethacrylate microchannel for bioseparation

Recent studies show that reduction in cross-sectional area can be used to improve the concentration factor in microscale bioseparations. Due to simplicity in fabrication process, a step reduction in cross-sectional area is generally implemented in microchip to increase the concentration factor. But the sudden change in cross-sectional area can introduce significant band dispersion and distortion. This paper reports a new fabrication technique to form a gradual reduction in cross-sectional area in polymethylmethacrylate (PMMA) microchannel for both anionic and cationic isotachophoresis (ITP). The fabrication technique is based on hot embossing and surface modification assisted bonding method. Both one-dimensional and two-dimensional gradual reduction in cross-sectional area microchannels were formed on PMMA with high fidelity using proposed techniques. ITP experiments were conducted to separate and preconcentrate fluorescent proteins in these microchips. Thousand fold and ten thousand fold increase in concentrations were obtained when 10 × and 100 × gradual reduction in cross-sectional area microchannels were used for ITP.     

Performance improvement of complementary feeders using static transfer switch system

The performance of complementary feeders, running in parallel, can be significantly improved by installing static transfer switches （STSs） at critical locations. We develop the STS control logic, which transfers the critical load from the preferred feeder to the alternate feeder when a voltage sag or a fault occurs on the preferred feeder. A forced commutation technique is proposed and implemented to turn off the preferred feeders＇ thyristor, thus avoiding cross current to flow and minimizing the transfer time. Simulation results show that the forced commutation technique is more effective as compared to the recently proposed time delay technique for STS operation. Two different feeders, namely New Exchange, the preferred feeder, and Sector 1-10/2, the alternate feeder of Islamabad Electric Supply COmpany （IESCO）, Pakistan, have been selected for case studies. The software PSCAD/EMTDC professional package has been used for simulation.     

Does performance in progressive assessment influence the outcome in final examination? An Australian experience

This paper investigates whether performance in progressive assessment necessarily influences the outcome in the end-of-semester final examination using the experience of an introductory postgraduate statistics course at a large Australian university. The average score on progressive assessments was higher than that of the final examination. Students attaining a higher distinction (HD) at the progressive assessment had a 37% chance of securing the same grade in the final examination, while students securing just a pass grade at the progressive assessment had 54 percent chance of failure in the final examination. Multiple regression analysis revealed that students’ performance in progressive assessments had a significant positive impact on final examination, so has the impact of learning diary. Mid-semester tests based exclusively on multiple choice questions (MCQs), more weights in progressive assessment and class-size appeared to have significant negative impact on the performance in the final examination. Focus group discussions suggest that (a) the final examination under timed conditions; (b) competing demands on time for final examination in other courses due contemporaneously; and (c) weaker motivation to sustain the momentum due to pass or near pass based on progressive assessments were the main hurdles in achieving better performance in the final examination.     

How do legal surprises drive organizational attention and case resolution? An analysis of false patent marking lawsuits

Legal surprises are unexpected suits or actions in which plaintiffs rely on claims or precedents that may be obscure, unfamiliar, or unknown to the defendants. Our study explores false patent marking suits, a unique type of patent-related legal surprise involving allegations of defendants marking products with ineligible patent numbers to deceive customers and/or deter competitors. An abrupt shift in U.S. Federal Courts’ interpretation of intellectual property rights (IPRs) policy amplified plaintiff incentives for filing these suits while escalating defendant penalties for proven violations. Handling costly legal surprises such as false patent marking suits requires focused attention from managers. Our core premise is that temporal and evidential cues in the timelines and storylines of plaintiffs’ legal narratives in surprise suits attract defendants’ organizational attention. We hypothesize about temporal focus (past, present, and future) and evidentiary reasoning (relevance, credibility, and inferential power) as attention cues and possible predictors of the mode (litigation or negotiation) and timing of case resolution. We apply automated content analysis to official court records for 992 false patent marking cases (2009–2011) and quantify competing risks using hazard models. We find that differences in temporal focus and evidentiary reasoning in the legal narratives of surprise suits are significant predictors of case resolution mode and timing. We also find that defendants countersuing to redirect plaintiffs’ attention is an effective negotiating tactic. We discuss the economic significance and strategic implications of our empirical findings on legal surprises, attention, case resolution mode and timing, and the unintended consequences of IPR policy changes.