Short‐Time Linear Quadratic Form Technique for Estimating Fast‐Varying Parameters in Feedback Loops

The precision of a closed‐loop controller system designed for an uncertain plant depends strongly upon the maximum extent to which it is possible to track the trend of time‐varying parameters of the plant. The aim of this study is to describe a new parameter estimation algorithm that is able to follow fast‐varying parameters in closed‐loop systems. The short‐time linear quadratic form (STLQF) estimation algorithm introduced in this paper is a technique for tracking time‐varying parameters based on short‐time analysis of the regressing variables in order to minimize locally a linear quadratic form cost function. The established cost function produces a linear combination of errors with several delays. To meet this objective, mathematical development of the STLQF estimation algorithm is described. To implement the STLQF algorithm, the algorithm is applied to a planar mobile robot with fast‐varying parameters of inertia and viscous and coulomb frictions. Next, performance of the proposed algorithm is assessed against noise effects and variation in the type of parameters.     

Prevention of hepatitis type B with specific immune serum globulin

In order to evaluate the preventive value of specific immune serum globulin against hepatitis type B, we have used this immune globulin in required doses in 12 patients (10 with AU antigen negative and 2 with AU antigen positive) with chronic renal failure who required maintenance hemodialysis for a period of 15 months, and we were able to prevent hepatitis type B in our dialysis patients.     

Analysis of transport phenomena within PEM fuel cells – An analytical solution

Transport phenomena within PEM fuel cells are investigated and a comprehensive analytical solution is presented. The methodology couples the transport within the fuel cell supply channels and the substrate which is composed of five different layers. The layers are all treated as macroscopically homogeneous porous media with uniform morphological properties such as porosity and permeability. The locally volume-averaged equations are employed to solve for transport through the porous layers. The problem encompasses complex interfacial transport phenomena involving several porous–porous as well as porous–fluid interfaces. Chemical reactions within the catalyst layers are also included. The method of matched asymptotic expansions is employed to solve for the flow field and species concentration distributions. Throughout the analysis, the choice of the gauge parameters involved in the perturbation solutions for velocity and concentration is found to be inherently tied to the physics of the problem and therefore an important physical metric. The analytical solution is found to be in excellent agreement with prior computational simulations. The analytical results are used to investigate several aspects of transport phenomena and their substantial role in PEM fuel cell operation. The solution presented in this work provides the first comprehensive analytical solution representing fuel cell transport phenomena.     

丹尼尔斯大厦 加拿大多伦多

正多伦多大学丹尼尔斯建筑、景观和设计学院的设计采用了分期的方法,包括修复和扩建以前称为"知识学院"的标志性建筑,将现有建筑物改造成与教学和需求更相关的框架体系。这个十九世纪遗址的总体规划是通过对预期用途模式和场地生态的分析而制定的,目的是重新定位校园西南角与安大略湖的轴线,并为学院创造新的特性。丹尼尔斯建筑、景观和设计学院需要一个可持续发展的新型工     

Synthesis and characterization of thiolated carboxymethyl chitosan-graft-cyclodextrin nanoparticles as a drug delivery vehicle for albendazole

A new strategy for the synthesis of thiolated carboxymethyl chitosan-g-cyclodextrin nanoparticles by an ionic-gelation method is presented. The synthetic approach was based on the utilization of 1,6-hexamethylene diisocyanate during cyclodextrin grafting onto carboxymethyl chitosan. The use of the 1,6-hexamethylene diisocyanate resulted in reactions between cyclodextrin and active sites at the C₆-position of chitosan, and preserved amino groups of chitosan for subsequent reactions with thioglycolic acid, as the thiolating agent, and tripolyphosphate, as the gelling counterion. Various methods such as scanning electron microscopy, rheology and in vitro release studies were employed to exhibit significant features of the nanoparticles for mucosal albendazole delivery applications. It was found that the thiolated carboxymethyl chitosan-g-cyclodextrin nanoparticles prepared using an aqueous solution containing 1 wt% of tripolyphosphate and having 115.65 (μmol/g polymer) of grafted thiol groups show both the highest mucoadhesive properties and the highest albendazole entrapment efficiency. The latter was confirmed theoretically by calculating the enthalpy of mixing of albendazole in the above thiolated chitosan polymer.     

Nanoporous organosilicas as preconcentration materials for the electrochemical detection of trinitrotoluene

We describe the use of nanoporous organosilicas for rapid preconcentration and extraction of trinitrotoluene (TNT) for electrochemical analysis and demonstrate the effect of template-directed molecular imprinting on TNT adsorption. The relative effects of the benzene (BENZ)- and diethylbenzene (DEB)-bridged organic-inorganic polymers, having narrow or broad pore size distributions, respectively, on electrochemical response and desorption behavior were examined. Sample volumes of 0.5-10 mL containing 5-1000 ppb TNT in a phosphate-buffered saline buffer were preconcentrated in-line before the detector using a microcolumn containing 10 mg of imprinted BENZ or DEB. Square-wave voltammetry was used to detect the first reduction peak of TNT in an electrochemical flow cell using a carbon working electrode and a Ag/AgCl reference electrode. Imprinted BENZ released TNT faster than imprinted DEB with considerably less peak tailing and displayed enhanced sensitivity and an improvement in the limit of detection (LOD) owing to more rapid elution of TNT from that material with increasing signal amplitude. For imprinted BENZ, the slope of signal versus concentration scaled linearly with increasing preconcentration volume, and for preconcentrating 10 mL of sample, the LOD for TNT was estimated to be 5 ppb. Template-directed molecularly imprinted DEB (TDMI-DEB) was 7-fold more efficient in adsorption of TNT from aqueous contaminated soil extract than nonimprinted DEB.     

Synthesis and flash sintering of (Hf1-xZrx)B2 solid solution powders

(Hf_1-xZr_x)B₂ solid solution powders were synthesized by two methods. First, solution-based processing of HfCl₄, ZrCl₄, sucrose, and H₃BO₃ was conducted followed by heat treatment in Argon to carry out the carbothermal reduction (CTR) reaction to form the diboride powders. Alternatively, in the so-called borohydride reduction (BHR) method, HfCl₄, ZrCl₄ and NaBH₄ were mixed in an Argon glove box followed by heat treatment in Argon at 700?1500 °C. The synthesized powders were characterized by XRD, SEM, TEM, EDS, and TGA, and the influence of different parameters such as starting composition, heat treatment temperature and time on products characteristics were revealed. Both CTR and BHR solid solution powders were then consolidated within ～5 min in a homemade flash sintering (FS) setup. The composition, microstructure, hardness, and thermal-oxidation properties of flash sintered ceramics were characterized, and the implication of this study and directions for future research were discussed.     

Critical assessment of arterial transport models

Works pertinent to arterial transport models are analyzed and a critical assessment of the models utilized in the study of fluid flow and mass transfer within the arteries is presented with an emphasis on the role of porous media. Arterial transport models are assessed and classified based on their ability to physically prescribe the arterial anatomy as well as the related transport processes. Pertinent models such as wall-free, homogeneous-wall, and multi-layer models as well as the governing equations and different types of boundary conditions utilized in each model are analyzed.     

Coherent vortical structures responsible for strong flux of scalar at free surface

We use direct numerical simulation data to study the identification of coherent vortical structures that generate strong scalar flux at the free surface of an open-channel turbulent flow. Using conventional conditional averaging of events with strong scalar surface flux or large vorticity components, we characterize the correlation of surface flux with a variety of subsurface vortical structures. We then present a clustering method based on the expectation–maximization algorithm which is shown to be effective in identifying dominant turbulence structure patterns. Using this method, clustering modes are obtained for different characteristic vorticity distributions on spanwise and streamwise vertical planes. It is found that each clustering mode can be constructed by a linear combination of a small number of enstrophy-containing eigenvectors obtained by proper orthogonal decomposition (POD). Compared with the POD eigenvectors, the clustering modes have a more direct correspondence to the turbulence structures in physical space. It is shown that ring-like and asymmetric cane vortices are the dominant vortical structures related to strong scalar surface flux in open-channel flow. The clustering method is general and can also be used for other types of flows and for applications beyond interfacial scalar transport.