Adaptive sliding mode control for a class of MIMO nonlinear systems with uncertainties

This paper proposes an adaptive scheme of designing sliding mode control (SMC) for affine class of multi-input multi-output (MIMO) nonlinear systems with uncertainty in the systems dynamics and control distribution gain. The proposed adaptive SMC does not require any a priori knowledge of the uncertainty bounds and therefore offers significant advantages over the non-adaptive schemes of SMC design. The closed loop stability conditions are derived based on Lyapunov theory. The effectiveness of the proposed approach is demonstrated via simulations considering an example of a two-link robot manipulator and has been found to be satisfactory.     

Transitions to Middle-Skill Jobs: Pathways Into the New Racio-Economic Structure of the 21st Century

College and Career Pathways is an educational policy initiative widely acclaimed as a commonsensical and effective measure to ease students’ transitions between secondary and postsecondary education and into the middle-skill jobs. This article investigates the internal dynamics of the Pathways’ curricular model as well as its underpinning assumptions and implications. First, it situates this development within the broader context of school-to-work reform efforts and explores its connections to the neoliberal ideological thinking. Drawing on Leonardo's (2012) critical raceclass theory of education as a conceptual lens, and with close attention to the new order of job categories, it then examines the rise of Pathways in light of the realities of class, race, and the asymmetrical power relations that characterize the modern nation state. The article concludes that pathways is best understood when situated within the dynamics of production and reproduction of a new class of workers for the new racio-economic structure of the 21st century.     

A sex education programme for mothers in Iran: Does preschool children’s sex education influence mothers’ knowledge and attitudes?

Mothers have an important role to play in teaching their children about sexual issues and shaping children’s sexual knowledge, attitudes and behaviours. In many cases, however, mothers themselves need help and support. This study was conducted to examine the effects of a sex education programme on the knowledge and attitudes of the mothers of pre-school children. Eighty mothers of pre-school children were randomly divided into an experimental and a control group. The experimental group received an education and training programme delivered over two 2-h sessions. The control group received no such intervention. Researcher-constructed knowledge and attitude questionnaires were completed by both groups before and one month after the intervention. Findings showed no significant differences between the two groups in terms of knowledge and attitudes before the training. After the education and training intervention, however, there was a significant increase in the mean score for both knowledge and attitudes in the experimental group compared to the control group. Study findings suggest that the sex education programme for the mothers of pre-school children can improve their knowledge and attitudes.     

Beneficial Effect of Aqueous Garlic Extract on Inflammation and Oxidative Stress Status in the Kidneys of Type 1 Diabetic Rats

One of the most important complications of diabetes is nephropathy. This study investigates the effects of aqueous garlic extract on inflammation and oxidative stress status in the kidneys of diabetic rats. Male rats were divided into four groups- control rats, diabetic rats, garlic extract-treated diabetic rats, garlic extract-treated normal rats. The glucose, urea, uric acid, and creatinine levels were measured in sera using colorimetric methods. To determine the oxidative stress condition in the kidney tissues, total antioxidant capacity (TAC), malondialdehyde (MDA), and total oxidant status (TOS) were measured using colorimetric methods. Inflammation status was evaluated by the determination of tumor necrosis factor-alpha (TNF-α) gene and protein expression using qRT-PCR and ELISA respectively, while nitric oxide (NO) level in these tissues was measured using the Griess method. Histological examination of Kidneys was carried out by H&E staining. The levels of glucose, urea, and uric acid were found to increase in the serum of diabetic rats and decrease in that of diabetic rats after treatment with garlic. Measurement of MDA, TOS, and TAC revealed oxidative stress in diabetic rats, which improved after receiving the extract. The NO and TNF-α protein levels in diabetic rats were higher than those in control rats. After treatment with garlic, the levels of TNF-α protein and NO became close to the normal levels. Histological results confirmed certain other data as well. Garlic has antioxidant properties; therefore, it can reduce oxidative stress, which plays an important role in the development of diabetic nephropathy. Reduction in oxidative stress has beneficial effects on inflammation because it leads to a decrease in the level of TNF-α.     

A novel controller for nonlinear uncertain systems using a combination of SDRE and function approximation technique: Regulation and tracking of flexible-joint manipulators

This paper presents a novel combined State Dependent Riccati Equation (SDRE) / Function Approximation Technique (FAT)-based control design for nonlinear uncertain systems. The SDRE is employed to construct an optimal controller and the function approximation technique is utilized to estimate time-varying disturbances and uncertainties. Moreover, a robust term in the proposed control law compensates for the truncation error. The closed-loop stability and boundedness of the tracking error and FAT weights approximation error are proved in the sense of Lyapunov, with consideration of truncation error. Due to the great importance of the adequate performance of transient response from practical point of view, performance evaluation has been accomplished. The proposed scheme is computationally simple due to utilizing the FAT to represent uncertainties and disturbances as a function of time. Compared with the SDRE based SMC, the proposed controller is superior in terms of capability to track a fast and highly complicated trajectory and no need to determine time-varying disturbances and uncertainties bounds. The case study is a Selective Compliant Articulated Robot for Assembly (SCARA) flexible joint manipulator as a representative of highly nonlinear, coupled, large robotic systems. Simulation results easily verify the effectiveness and superiority of the proposed controller.