A Numerical Approach for Solving Optimal Control Problems Using the Boubaker Polynomials Expansion Scheme

In this paper, we present a computational method for solving optimal control problems and the controlled Duffing oscillator. This method is based on state parametrization. In fact, the state variable is approximated by Boubaker polynomials with unknown coefficients. The equation of motion, performance index and boundary conditions are converted into some algebraic equations. Thus, an optimal control problem converts to a optimization problem, which can then be solved easily. By this method, the numerical value of the performance index is obtained. Also, the control and state variables can be approximated as functions of time. Convergence of the algorithms is proved. Numerical results are given for several test examples to demonstrate the applicability and efficiency of the method

A novel non-invasive intervention for removing occlusions from shunts using an abrading magnetic microswarm.

Objective: Shunts are often employed as internal medical devices for draining aberrant fluids from organs. However, depositions of calcification in the shunt walls lead to its failure, requiring frequent replacements. The current surgical procedures for implanting shunts are invasive. Methods: This paper introduces a novel, non-invasive approach for eliminating shunt deposits. In this non-invasive intervention, a swarm of magnetic nanoparticles (MNPs) guided by an external magnetic field removes the shunt deposition. A prototype device was fabricated to provide a proof of concept. MNPs were steered within the shunt channel containing calcification layers and successfully abraded the deposition layer. The proof-of-concept experiments used a moving magnetic field ranging from 0.1 to 0.3 T and a velocity between 1 to 12 cm/s. The average nanoparticles size was 45nm. Five diverse contact theories predicted the amount of wear and indentation depth created by the abrading microswarm. Results: Experimental results confirm that MNPs under a moving magnetic field can abrade shunt deposits. Also, there is a direct relation between the intensity of the magnetic field, the speed of magnet movement, and the rate of abrading the calcification deposits. The simulation results showed that the Hoeprich model deviated 12.1% from the experimental results and was the most suitable model. Conclusion & significance: This research has introduced a novel minimally invasive approach to remove shunt depositions that can reduce the number of revision surgeries and prevent surgical complications

Environmental predictors for the distribution of the Caspian green lizard, Lacerta strigata Eichwald, 1831, along elevational gradients of the Elburz Mountains in northern Iran

Within its range, the Caspian green lizard, Lacerta strigata, occurs in the Elburz Mountains (northern Iran) at elevations from below sea level to approximately 2700 m a.s.l. To determine the environmental factors affecting the distribution of this lizard, we used an ensemble approach to model the distribution of the Caspian green lizard (Lacerta strigata) in Iran using four algorithms (generalized boosted model, maximum entropy, generalized linear model, random forest). Results revealed that low-elevation habitats between the Elburz Mountains and the Caspian Sea are the most suitable habitats for the species. The normalized difference vegetation index (NDVI), annual precipitation (both with positive relationships), and altitude (with a negative relationship) were the most important environmental variables influencing the distribution of the species. NDVI was likely the most important variable because it is an indicator of plant productivity, which presumably influences the availability of food resources such as insects. We also tested the validity of an old distribution record for the species near Shiraz in southwestern Iran. The results show that southwestern Iran is not ecologically suitable for the species. As our results highlighted that the NDVI strongly affects distribution of the species, we suggest protection of vegetation cover in the habitat of the species for conservation of Lacerta strigata

Habitat modeling of the common pheasant Phasianus colchicus (Galliformes: Phasianidae) in a highly modified landscape: application of species distribution models in the study of a poorly documented bird in Iran

The common pheasant is listed as a nationally protected species in Iran because it faces many threats such as habitat destruction, pollution from pesticides and overhunting. The species’ habitat selection remains unknown in Iran; consequently, conservation planning for the species is hampered by this lack of information. In this study we used predictor variables including topographic, anthropogenic, land cover and climate and 122 occurrence points to model the distribution of common pheasant (subspecies P. c. talischensis), in Gilan province, Iran. The results showed that distance to agriculture and orchards as well as distance to plantation forests were the most important variables in predicting species distribution. Furthermore, we found that the total potential suitable habitat for the species in Gilan province is 315,990 hectares. We observed a shift of the species to higher altitudes in the province. We recommend raising awareness about the presence of the species especially among private landowners, creating a network of protected areas on private land, and changing land-use policies at the provincial level as essential measures for the conservation of the species in Gilan province. Our results can be applied to management and conservation of the species in other modified or rapidly changing landscapes

Seismic Evaluation of a Tailings Dam Using Uncoupled and Fully Coupled Soil Constitutive Models

The Henderson Tailings Storage Facility (TSF) is an active facility located near Parshall, Colorado, consisting of two dams – 1 Dam and 3 Dam. The upstream method of construction has been used for tailings deposition since the mid-1970s. This paper presents the results of the seismic evaluation of 1 Dam using multiple constitutive modeling methodologies: an uncoupled Mohr-Coulomb approach and a fully coupled critical state-compatible PM4Sand/Silt approach. The analyses were completed to study the seismic response of the tailings embankment under the Maximum Design Earthquake (MDE) with a return period of 10,000 years. The numerical analyses showed that the results of the fully coupled, effective stress PM4 models were generally consistent with the uncoupled Mohr-Coulomb models. The PM4 models have the capability to estimate the generation of excess pore water pressure and onset of soil liquefaction during the application of the input ground motion. Subsequent zones of tailings materials that were prone to soil liquefaction or strength loss were identified based on two criteria: 1) excess pore water pressure ratio; and 2) shear strain in the PM4 modeling. This study provides valuable insights into the methods used to estimate seismic response of the Henderson TSF and highlights the importance of using properly calibrated advanced constitutive modeling methodologies to capture the complex response of tailings materials under seismic loading. The fully coupled models were capable of capturing the hysteretic soil response, including stress-strain response and accumulation of plastic shear strains, providing confidence in the predicted modes of deformation and informing the design and management of the facility.Non UBCUnreviewedOthe

Histopathological evaluation of the effect of vitamin E on rat kidney after complete unilateral urethral obstruction

Vitamin E is an important antioxidant, which plays a vital role in preventing free radical induced reperfusion injuries. Any disorder in the normal urinary flow is termed obstructive nephropathy which could ultimately lead to hydronephrosis, atrophy and complete impairment of renal function. The aim of this study was to determine the effect of vitamin E on renal tissue following complete unilateral urethral obstruction in the rat. In this experimental study, 30 adult male Sprague-Dawley rats were randomly divided into three groups each containing 10 rats. The first group was considered as the control group. Following Unilateral urethral obstruction (UUO), rats in the second group received olive oil intraperitoneally for 15 days starting one day before surgery. Group three rats were given 50 Iu/kg of Vitamin E intraperitoneally for 15 days starting one day before unilateral obstruction (UUO-Vit E). Rats were euthanized at day 14 after surgery for histopathological evaluation and their left kidneys were collected and fixed in formalin and stained with Hematoxylen and Eosin, Trichrome-masson and Periodic Acid Schiff techniques. Histopathological evaluation revealed dilation of the Bowman’s capsule, severe glomerular and tubular atrophy, periglomerular sclerosis, interstitial infiltration of mononuclear cells, severe diffuse tubular degeneration, epithelial thickening of Bowman’s capsule, perivascular edema, interstitial fibrosis, hemorrhage and sub capsular fibrosis in the UUO group. Vitamin E administration in the UUO-Vit E group significantly decreased renal tissue lesions and fibrosis. The result of the present study indicated that urethral obstruction leads to severe renal fibrosis and tissue damage and concurrent administration of Vitamin E decreases tissue lesions and fibrosis resulting from the obstruction