Synthesis of fluorinated polymer electrolyte membranes by radiation grafting and atom transfer radical polymerization techniques

A novel polymer electrolyte membrane was synthesized by radiation-induced grafting and consequent atom transfer radical polymerization (ATRP). First, bromine-containing perfluorinated grafts were prepared by radiation grafting of 2-bromotetrafluoroethyl trifluorovinyl ether (BrTFF) into a poly(ethylene-co-tetrafluoroethylene) (ETFE) film. Then, the bromine atoms in the ETFE-g-PBrTFF grafted films were acted as initiators, and the films were treated with Cu(I)-based catalytic system of a CuBr and 2,2′-bipyridyl (bpy) for the ATRP. By adjusting the molar ratio of initiator/CuBr/bpy and the reaction temperature, branched poly(styrene) with a grafting yield of above 100% on the poly(BrTFF) main chains was constructed in ETFE-g-PBrTFF films. Thermal analysis revealed that the perfluorinated poly(BrTFF) main chains were miscible to ETFE, whereas the hydrocarbon poly(styrene) branches were phase-separated from the ETFE-g-PBrTFF film. Sulfonic groups could be further introduced into the poly(styrene) grafts of ETFE-g-PBrTFF-g-PS films with homogeneous distribution in a perpendicular direction to the membrane surface. The resulting membrane with a styrene grafting yield of 15% exhibited higher proton conductivity than commercial Nafion 117 membrane. Likewise, it had better chemical stability than ETFE-g-PSSA membrane prepared by conventional radiation-induced grafting.     

Physical Factors Determining Thermal Conductivities of Isotropic Conductive Adhesives

The thermal conductivities of a typical isotropic conductive adhesive (ICA) composed of an epoxy-based binder containing flake-shaped and spherical Ag particles have been studied. The ICA specimens exhibit anisotropy in their thermal conductivities between the vertical and in-plane directions. In addition, their thermal conductivities apparently depend on their thermal history during the curing and subsequent annealing processes, even if they are fully cured during the preliminary curing stage. The thermal conductivities tend to increase with decreasing electrical resistivities. The experimental values for the thermal conductivities of the ICA specimens were apparently higher than␣those predicted using Bruggemann’s equation. Analysis using the Wiedemann–Franz (W–F) law indicates that their thermal conductivities increase with increasing contribution from electrical conduction. In order to discuss the thermal conductivities of ICA specimens that exhibit relatively low electrical resistivities (below 10⁻³ Ω cm), the contribution of the conducting electrons must be included.     

Effect of carbon nanomaterials on the germination and growth of rice plants

For the successful diverse applications of different nanomaterials in life sciences, it is necessary to understand the ultimate fate, distribution and potential environmental impacts of manufactured nanomaterials. Phytotoxicity studies using higher plants is an important criterion for understanding the toxicity of engineered nanomaterials. We studied the effects of engineered carbon nanomaterials of various dimensionalities (carbon nanotubes, C60, graphene) on the germination of rice seeds. A pronounced increase in the rate of germination was observed for rice seeds in the presence of some of these carbon nanostructures, in particular the nanotubes. Increased water content was observed in the carbon nanomaterial treated seeds during germination compared to controls. The germinated seeds were then grown in a basal growth medium supplemented with carbon nanomaterials for studying their impact on further seedling growth. Treated seedlings appeared to be healthier with well-developed root and shoot systems compared to control seedlings. Our results indicate the possible use for carbon nanomaterials as enhancers in the growth of rice seedlings.     

Bauschinger effect and multiaxial yield behavior of stress-reversed mild steel

Thin-walled cylindrical specimens subjected to torsional prestraining are stress-reversed along the Bauschinger curve. The Bauschinger effect (BE), yield behavior, and flow behavior of the stress-reversed mild steel were examined by using combined loadings of axial load, internal pressure, and torsion. The results indicate that the stress-reversed steel has the same yield stress at 0.2 pct offset strain in reloading tests of forward and reverse torsion, when the reverse strain is =0.77 pct. Furthermore, it is possible to cause the yield stresses in forward and reverse torsion to coincide in any offset strain. The yield locus of the stress-reversed steel is symmetric with respect to the tensile stress axis in a tension-torsion stress field. However, it has been found to be an anisotropy in the stress-reversed steel, and the magnitude of anisotropy is related to the offset strain. For example, there is a stronger anisotropy at 0.2 pct offset strain than at 2 pct offset strain, even though the BE is eliminated for the former. It is shown that the reduction in the BE by stress reversal is concerned with the relief of the long-range back-stress generated by prestraining. Besides, the roles of aging in the stress-aging process lie in the contributions to age hardening and development of directional back-stress.     

Development of a high performance electrochemical wastewater treatment system

In order to construct a high performance electrochemical system for practical use in industrial and municipal wastewater treatment, laboratory scale electrochemical experiments were performed to select anode materials by applying pulse voltage. Based on the results obtained from laboratory experiments, a pilot plant of electrochemical treatment system (0.3 m3 h(-1)) was successfully developed, in which electrocoagulation and electrooxidation processes were used. The performance of the treatment system was evaluated by treating domestic wastewater, pond water containing algae and wastewater from hog raising. As a result, production of hydroxyl radicals detected with p-nitrosodimethylaniline (RNO) at Ti/RuO(2)-TiO(2) anode was larger than with a platinum anode, and hydroxyl radicals were not detected at Ti anode. Moreover, a significant difference in electrocatalytic properties for ammonia oxidation between platinum and Ti/RuO(2)-TiO(2) electrodes was not observed from the cyclic voltammogram. The removal of T-N, T-P, NH(4)-N and COD from domestic wastewater and pond water containing algae was approximately 90%, while the removal of chlorophyll-a (chl-a) of algae was approximately 100%. Although the electrochemical treatment system was effective on biologically treated wastewater from hog raising, the treatment of raw wastewater was not remarkable. Therefore, the electrochemical treatment system requires pretreatment when used with wastewater containing high concentrations of suspended solids.     

Control System Design Automation for Mechanical Systems

In this paper, a user-friendly and comprehensive control system design package called Control System Design Automation (CSDA) is described. The system consists of five main blocks: a requirement interpretation block, a modeling block, an analysis/design block, a database management and knowledge base block, and a verification block. The requirement interpretation block transforms the specifications in terms of the application to those in terms of control. The analysis/design block selects an optimal control structure and determines the controller parameters. In addition to the conventional design methods, CSDA also contains the more recent design methods such as the LMI design approach and the Kessler/Manabe method. The LMI approach can obtain a controller which satisfies multiple specification items at the same time. The configuration of the system as well as the analysis/design block are described in detail in this paper.     

Artificial life based on the programmed self-decomposition model, SIVA

To examine the effect and significance of the phenomenon of death, we have developed an artificial life simulator, SIVA-III (simulator for individuals of virtual automata III), based on a “programmed self-decomposition model”. The architecture of this simulator consists of a “finite heterogeneous habitation environment” and “artificial life with programmed individual death and concurrent self-decomposition”. We conducted experiments under various settings to comparare and contrast mortal life and immortal life. The results clearly demonstrated the validity of a self-decomposing, programmed individual death, and the limitations inherent in immortal life, suggesting a striking superiority of mortal life over immortal life. This work was presented in part at the Fifth International Symposium on Artificial Life and Robotics, Oita, Japan, January 26–28, 2000     

Self-intersections of offsets of quadratic surfaces: Part I, explicit surfaces

Although offset surfaces are widely used in various engineering applications, their degenerating mechanism is not well known in a quantitative manner. Offset surfaces are functionally more complex than their progenitor surfaces and may degenerate even if the progenitor surfaces are regular. Self-intersections of the offsets of regular surfaces may be induced by concave regions of surface where the positive offset distance exceeds the maximum absolute value of the negative minimum principal curvature or the absolute value of the negative offset distance exceeds the maximum value of the positive maximum principal curvature. It is well known that any regular surface can be locally approximated in the neighborhood of a pointp by the explicit quadratic surface of the form r(x,y)=[x,y1/2(x²+y²)]^T to the second order where – and – are the principal curvatures at pointp. Therefore investigations of the selfintersecting mechanisms of the offsets of explicit quadratic surfaces due to differential geometry properties lead to an understanding of the self-intersecting mechanisms of offsets of regular parametric surfaces. In this paper, we develop the equations of the self-intersection curves of an offset of an explicit quadratic surface. We also develop an algorithm to detect and trace a small loop of a self-intersection curve of an offset of a regular parametric surface based on our analysis of offsets of explicit quadratic surfaces. Examples illustrate our method.     

New evaluation technique of interfacial properties in GFRP

A new method was proposed to evaluate the mechanical properties at the interface between the fibres and the matrix in composites using an embedded single fibre coupon test. A mechanical parameter at the interface (called the interfacial transmissibility, ) was derived from the fibre strength and the apparent stress of the fibre immediately before the first fracture of embedded fibre, _fa. This parameter indicated the degree of the mechanical transmission from the matrix to the fibre through the interface. This avoided some complicated problems such as the stress distribution along fibre fragments and the critical fragment state in a typical single-fibre test. This new method was tried to determine the -values for a fibre glass/epoxy resin with different amounts of a coupling agent at the interface. In order to measure the stress at the first fracture, the fracture process was monitored with a video camera during the single fibre test. The stress values at the first fracture for many coupons were analysed as a function of the three-parameter Weibull distribution. The resulting average stress and its coefficient of variation indicated that the reliability of the measurement for the stress at the first fracture was not less than that obtained by the usual single-fibre test. The change of interfacial transmissibility with amount of the coupling agent revealed the existence of an optimal interface.     

Solving nonlinear polynomial systems in the barycentric Bernstein basis

We present a method for solving arbitrary systems of N nonlinear polynomials in n variables over an n-dimensional simplicial domain based on polynomial representation in the barycentric Bernstein basis and subdivision. The roots are approximated to arbitrary precision by iteratively constructing a series of smaller bounding simplices. We use geometric subdivision to isolate multiple roots within a simplex. An algorithm implementing this method in rounded interval arithmetic is described and analyzed. We find that when the total order of polynomials is close to the maximum order of each variable, an iteration of this solver algorithm is asymptotically more efficient than the corresponding step in a similar algorithm which relies on polynomial representation in the tensor product Bernstein basis. We also discuss various implementation issues and identify topics for further study.