Activated sludge-loaded polyvinyl alcohol microparticles for starch wastewater treatment in an airlift bioreactor

Emulsification followed by freezing and thawing cycles was applied to produce poly(vinyl alcohol) (PVA) microparticles and to simultaneously immobilize activated sludge. Activity of the obtained microparticles (～400 μm in diameter) was evaluated in glucose syrup solutions and heat-pretreated wastewater from a starch factory by measurements of permanganate index (COD _Mn ) reduction. The reaction followed first-order kinetics, revealing slight mass transfer limitations in PVA microparticles as determined from the kinetic rate constant that was ～35% lower than that in the freely suspended activated sludge culture. Yet, efficiency of the microparticles increased almost five-fold in a laboratory airlift bioreactor operating either in batch or continuous regimes. Over 19 days of operation under high organic loadings in the industrial wastewater (～100 kgCOD m^?3 d^?1), PVA microparticles (12.4% volume fraction) remained active and induced a decrease of over 90% of biodegradable COD _Mn at the hydraulic retention time of 8 h.     

Application of feedforward neural network in the study of dissociated gas flow along the porous wall

This paper concerns the use of feedforward neural networks (FNN) for predicting the nondimensional velocity of the gas that flows along a porous wall. The numerical solution of partial differential equations that govern the fluid flow is applied for training and testing the FNN. The equations were solved using finite differences method by writing a FORTRAN code. The Levenberg–Marquardt algorithm is used to train the neural network. The optimal FNN architecture was determined. The FNN predicted values are in accordance with the values obtained by the finite difference method (FDM). The performance of the neural network model was assessed through the correlation coefficient (r), mean absolute error (MAE) and mean square error (MSE). The respective values of r, MAE and MSE for the testing data are 0.9999, 0.0025 and 1.9998 · 10^?5.     

A Higher-Order Asymptotic Theory for Fully Developed Turbulent Flow in Smooth Pipes

A complete second-order asymptotic theory for fully developed turbulent flow in smooth pipes at high turbulent Reynolds numbers is presented in the paper. The theory is based on Prandtl's mixing-length hypothesis involving a fourth-order polynomial representation for the mixing length and taking into account its dependence on the Reynolds number. Two main contributions with respect to the existing literature have been achieved:(a) the friction law is obtained by asymptotic evaluation of an integral, completely independently of the velocity field, and(b) an axis layer (in addition to the wall layer and the outer layer) has to be included in the analysis in order to remove a nonuniformity appearing in the second-order solution for the velocity fieldClosed-form analytic expressions for all constants and wake functions appearing up to the second-order solution in both the friction law and the velocity field are obtained. The results are in a very good agreement with experiments.     

Properties of thermomechanically rolled Nb/Ti microalloyed steel sheets

Structure and mechanical properties of a Nb/Ti microalloyed steel, thermomechanically rolled on a strip-production facility, are evaluated. Small (0.02%) titanium addition to niobium-containing steel is found to increase precipitation while reducing grain-refining potential of niobium. This effect increases with increasing finish-rolling temperature, and is also reflected in an increased charpy energy transition temperature. A reduced tendency for precipitation in a nitrogen-free austenite together with the short interpass times in the finishing train, is assumed to reduce the tendency for pancaking, which is prerequisite for an effective grain refining.     

Almost constant-time 3D nearest-neighbor lookup using implicit octrees

A recurring problem in 3D applications is nearest-neighbor lookups in 3D point clouds. In this work, a novel method for exact and approximate 3D nearest-neighbor lookups is proposed that allows lookup times that are, contrary to previous approaches, nearly independent of the distribution of data and query points, allowing to use the method in real-time scenarios. The lookup times of the proposed method outperform prior art sometimes by several orders of magnitude. This speedup is bought at the price of increased costs for creating the indexing structure, which, however, can typically be done in an offline phase. Additionally, an approximate variant of the method is proposed that significantly reduces the time required for data structure creation and further improves lookup times, outperforming all other methods and yielding almost constant lookup times. The method is based on a recursive spatial subdivision using an octree that uses the underlying Voronoi tessellation as splitting criteria, thus avoiding potentially expensive backtracking. The resulting octree is represented implicitly using a hash table, which allows finding the leaf node a query point belongs to with a runtime that is logarithmic in the tree depth. The method is also trivially extendable to 2D nearest neighbor lookups.     

Longitudinal air permeability of pinewood with beetle transmitted blue-stain

The mountain pine beetle epidemic is destroying an extensive volume of the lodgepole pine forests being one of the most commercially harvested trees in British Columbia. The purpose of this study was to test the permeability of wood of four different classes regarding the time of the beetle attack. The experiments used the ‘‘falling water’’ unsteady-steady method of measuring superficial air permeability. The results showed that the specific permeability is not significantly different between the infested classes tested. The same conclusion could be reached for comparisons of uninfected and infested wood.     

Parking assistance using dense motion-stereo

The ability of generating and interpreting a three-dimensional representation of the environment in real-time is one of the key technologies for autonomous vehicles. While active sensors like ultrasounds have been commercially used, their cost and precision is not favorable. On the other hand, integrating passive sensors, like video cameras, in modern vehicles is quite appealing especially because of their low cost. However, image processing requires reliable real-time algorithms to retrieve depth from visual information. In addition, the limited processing power in automobiles and other mobile platforms makes this problem even more challenging. In this paper we introduce a parking assistance system which relies on dense motion-stereo to compute depth maps of the observed environment in real-time. The flexibility and robustness of our method is showcased with different applications: automatic parking slot detection, a collision warning for the pivoting ranges of the doors and an image-based rendering technique to visualize the environment around the host vehicle. We evaluate the accuracy and reliability of our system and provide quantitative and qualitative results. A comparison to ultrasound and feature-based motion-stereo solutions shows that our approach is more reliable.     

Prospects of wind energy sector development in Serbia with relevant regulatory framework overview

The growth of the renewable energy sector in the world in the first decade of the twenty-first century was rapid. Wind energy sector was one of the fastest growing renewable energy technologies. In this paper, authors have tried to review the current state of wind power utilization in Serbia as one of the most penetrating RES technologies in the world. The brief overview of electric power sector in Serbia was given in order to describe the environment for emerging wind energy sector development. Sufficient wind energy resources were identified in several regions of the country. Current energy policy in Serbia was reviewed in terms of the regulations that have to be followed in order to meet the requirements for RES power plants, i.e. wind power plant construction. In subsequent section short reviews of wind energy projects which are in their initial phases are provided. The wind energy sector in Serbia is emerging despite the difficulties faced by the investors, regulatory bodies and other shareholders, in the course of the past several years. There is an urgent need of a broader transfer of specific knowledge and technologies related to wind farms and wind turbines in order to speed up the current wind energy sector development.     

Calcium–Alginate–Inulin Microbeads as Carriers for Aqueous Carqueja Extract

Carqueja (Pterospartum tridentatum) is an endemic species and various bioactive compounds have been identified in its aqueous extract. The aim of this study was to protect the natural antioxidants from the aqueous extract of carqueja by encapsulation in Ca–alginate microbeads and Ca–alginate microbeads containing 10% and 20% (w/v) of inulin. The microbeads produced by electrostatic extrusion technique had an average diameter from 625 μm to 830 μm depending on the portion of inulin. The sphericity factor of the hydrogel microbeads had values between 0.014 and 0.026, while freeze dried microbeads had irregular shape, especially those with no excipient. The reduction in microbeads size after freeze drying process (expressed as shrinkage factor) ranged from 0.338 (alginate microbeads with 20% (w/v) of inulin) to 0.523 (plain alginate microbeads). The expressed radical scavenging activity against ABTS and DPPH radicals was found to be between 30% and 40% for encapsulated extract, while the fresh extract showed around 47% and 57% of radical scavenging activity for ABTS and DPPH radicals, respectively. The correlation between antioxidant activity and the total phenolic content were found to be positive (in both assay methods, DPPH and ABTS), which indicate that the addition of inulin didn't have influence on antioxidant activity. The presence of inulin reduced stiffness of the hydrogel, and protected bead structure from collapse upon freeze‐drying. Alginate–inulin beads are envisaged to be used for delivery of aqueous P. tridentatum extract in functional food products.