Fuzzy Logic Applied to the Inverter of a SOFC Power Plant

Solid‐oxide fuel cell (SOFC) units normally supply power to the local load centers but the excess power can also be exported to the regional power grid, adding to the capacity and stability of the overall grid system. A SOFC power plant is equipped with a pulse width modulation (PWM) inverter. This paper presents the design of a new fuzzy logic regulator for a three‐phase inverter, using the strategy of an inverter flux vector control method. Criteria for designing the fuzzy controller are given and a comparison with the hysteresis method is presented. The flux vector approach is to generate the command pulses for low ripple current and constant switching frequency.     

Time-Dependence of the Adhesion of Micrometer-Size Particles to Substrates: Correlation with Postdeposition Particle Rotation

The time dependence of the detachment force of 7-µm ground polyester particles coated with silica nanoparticles from a ceramer-coated substrate was determined by ultracentrifugation. The detachment force of the particles from the substrate was found to increase with the time since the particle deposition. Scanning electron microscopy (SEM) results show that, following deposition, the particles rotate at approximately the same scale as the observed increase in the detachment force. This suggests that the increase in adhesion may be due to particle rotation from their initial positions obtained upon deposition to a more stable position that results from torques generated by either electrostatic or van der Waals forces acting on the particles.     

Investigation of Shape Transformations of Vesicles,Induced by Their Adhesion to Flat Substrates Characterized by Different Adhesion Strength

The adhesion of lipid vesicles to a rigid flat surface is investigated. We examine the influence of the membrane spontaneous curvature, adhesion strength, and the reduced volume on the stability and shape transformations of adhered vesicles. The minimal strength of the adhesion necessary to stabilize the shapes of adhered vesicles belonging to different shape classes is determined. It is shown that the budding of an adhered vesicle may be induced by the change of the adhesion strength. The importance of the free vesicle shape for its susceptibility to adhesion is discussed.     

Amino Organo Alkoxysilanes in Organic Solvents for Promoting Adhesion of Polyimide Films to Silicon Substrates

In this study of silane adhesion promoters for coupling polyimide films to clean silicon dioxide surfaces the adhesion values obtained with three amino organo trialkoxysilanes and with several solvents for these silanes were compared. When applied from aqueous solution the silanes with primary amino groups gave higher adhesion values, as measured by a peel test, than did one having only a secondary amino group; however, when applied from organic solvents all three were effective. The highest values for all of the solvents tested were obtained with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane. A fundamental discussion is presented to rationalize the differences.     

Adhesion of Different Concrete Repair Systems Exposed to Different Environments

This article presents the results of experiments conducted to assess the effects of aging under dry laboratory conditions, underwater storage, cyclic freeze-thaw, and temperature changes on the adhesion between the repair and the substrate concrete. The repair systems considered for these studies included ordinary sand/cement (S/C) mortar, with and without bonding agents, two polymer modified cementitious mortars, and two resinous mortars. The specimens were concrete slabs of 600 × 300 × 100 mm dimensions with saw cut face 600 × 300 mm on which a repair layer of 20 mm had been applied. In order to eliminate the effects of surface texture and surface strength of the concrete on the adhesion of repair systems, repair applied surfaces were all saw cut surfaces of concrete with 28-day design compressive strength of 65 MPa. Tensile bond strengths of these specimens were measured using a direct tensile test (pull-off) method. The results indicated that the tensile bond strengths of different repair systems under dry laboratory conditions, and stored underwater, ranged from 1.51 to 5.27 Mpa. Exposure to 300 cycles of freeze-thaw and to 200 cycles of temperature changes resulted in 6 to 100 percent reduction in their tensile bond strengths.     

Using Twist-off Method for Measuring CFRP/Concrete Adhesion when Exposed to Cyclic Temperature Changes,Wet-Dry and Freeze-Thaw

Materials such as fiber-reinforced plastics (FRPs) are lightweight, strong, and for the most part, non-corrodible. Hence, the use of FRPs as retrofitting materials for concrete represents a viable, durable alternative to conventional practice using reinforcing steel. This paper addresses the magnitude of the residual shear bond strengths between rigid and flexible carbon fiber reinforced plastic (CFRP) sheets and substrate concrete, after being subjected to cyclic temperature changes, wet-dry and freeze-thaw, by means of a Twist-off method. In the experimental investigation, the shear bond strength of a number of CFRP/concrete specimens was monitored. These results were then used to make comparisons between the behaviors of the two types of CFRPs. Analysis of the results indicated that while 180 freeze-thaw cycles destroy the shear bond strength of rigid and flexible CFRP completely, the same number of wetting and drying and temperature change cycles can reduce these bonds by up to about 30 and 20%, respectively. The results also showed that despite the insignificant flexible CFRP failure, the failure in the rigid CFRP material was noticeable.     

Adhesion of Different Concrete Repair Systems Exposed to Different Environments

This article presents the results of experiments conducted to assess the effects of aging under dry laboratory conditions, underwater storage, cyclic freeze-thaw, and temperature changes on the adhesion between the repair and the substrate concrete. The repair systems considered for these studies included ordinary sand/cement (S/C) mortar, with and without bonding agents, two polymer modified cementitious mortars, and two resinous mortars. The specimens were concrete slabs of 600 × 300 × 100 mm dimensions with saw cut face 600 × 300 mm on which a repair layer of 20 mm had been applied. In order to eliminate the effects of surface texture and surface strength of the concrete on the adhesion of repair systems, repair applied surfaces were all saw cut surfaces of concrete with 28-day design compressive strength of 65 MPa. Tensile bond strengths of these specimens were measured using a direct tensile test (pull-off) method. The results indicated that the tensile bond strengths of different repair systems under dry laboratory conditions, and stored underwater, ranged from 1.51 to 5.27 Mpa. Exposure to 300 cycles of freeze-thaw and to 200 cycles of temperature changes resulted in 6 to 100 percent reduction in their tensile bond strengths.     

Time-Dependence of the Adhesion of Micrometer-Size Particles to Substrates: Correlation with Postdeposition Particle Rotation

The time dependence of the detachment force of 7-µm ground polyester particles coated with silica nanoparticles from a ceramer-coated substrate was determined by ultracentrifugation. The detachment force of the particles from the substrate was found to increase with the time since the particle deposition. Scanning electron microscopy (SEM) results show that, following deposition, the particles rotate at approximately the same scale as the observed increase in the detachment force. This suggests that the increase in adhesion may be due to particle rotation from their initial positions obtained upon deposition to a more stable position that results from torques generated by either electrostatic or van der Waals forces acting on the particles.     

Adhesion Improvement of Poly(Phenylene-Vinylene) Substrates Induced by Argon-Oxygen Plasma Treatment

Copper films evaporated on argon-oxygen plasma-treated poly(phenylene-vinylene) films have been studied by scratch test, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The adhesion of the metallic film to the polymer substrate was greatly enhanced after treatment and found to increase with the treatment time. SEM observation of the treated samples revealed that the morphology of the polymer surface was gradually changed with the treatment time as compared with that of the bare polymer film. On the other hand, XPS analysis of the polymer-metal interface showed that the bonding between carbon, oxygen and copper were subsequently modified as compared with those obtained in untreated samples. The high adhesion strength observed on these substrates was related to the modification in the surface morphology on the one hand and to the formation of new compounds at the polymer-metal interface on the other. The nature of the interfacial layer and its influence on the adhesion of the copper layer was discussed by comparing the results with those obtained in poly(phenylene-vinylene) (PPV)-Al systems.     

Adhesion Improvement of Poly(Phenylene-Vinylene) Substrates Induced by Argon-Oxygen Plasma Treatment

Copper films evaporated on argon-oxygen plasma-treated poly(phenylene-vinylene) films have been studied by scratch test, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The adhesion of the metallic film to the polymer substrate was greatly enhanced after treatment and found to increase with the treatment time. SEM observation of the treated samples revealed that the morphology of the polymer surface was gradually changed with the treatment time as compared with that of the bare polymer film. On the other hand, XPS analysis of the polymer-metal interface showed that the bonding between carbon, oxygen and copper were subsequently modified as compared with those obtained in untreated samples. The high adhesion strength observed on these substrates was related to the modification in the surface morphology on the one hand and to the formation of new compounds at the polymer-metal interface on the other. The nature of the interfacial layer and its influence on the adhesion of the copper layer was discussed by comparing the results with those obtained in poly(phenylene-vinylene) (PPV)-Al systems.     

C60自密实混凝土氯离子渗透和抗冻性能研究

采用绝对体积法配制C60自密实混凝土,研究C60自密实混凝土工作性能、不同龄期立方体抗压强度、混凝土氯离子渗透和抗冻融循环性能.结果表明:新拌自密实混凝土流动性能满足二级自密实混凝土要求;28 d标准养护后,抗压强度达标;6 h电通量较低,抗氯离子渗透性能优良;200次冻融循环后动弹性模量损失率26.05%,低于标准规定上限,试件质量损失率1.86%,抗冻性能良好.研究结果为自密实混凝土的推广应用提供依据参考.     

LabVIEW中模糊控制器的设计及应用

通过火电厂给水加氨模糊控制实例 ,详细介绍利用LabVIEW提供的模糊逻辑工具箱 (FuzzyLogicforGToolkit)设计开发模糊控制器的方法。     

Adhesion of resin composite to enamel and dentin: a methodological assessment

This study compared the impact of four test methods on adhesion of resin composite to enamel and dentin. Human molars (N = 54) were randomly assigned to test the adhesion of resin composite material (Quadrant Universal LC) using one of the following test methods: (a) macroshear test (SBT; n = 16), (b) macrotensile test (TBT; n = 16), (c) microshear test (μSBT; n = 16) and (d) microtensile test (μTBT; n = 6). In a randomized manner, buccal or lingual surfaces of each tooth, were assigned as enamel or dentin substrates. Enamel and dentin surfaces were conditioned using an etch-and-rinse adhesive system (Syntac Classic). After storage (24 h, 37 °C), bond tests were conducted in a Universal Testing Machine (1 mm/min) and failure types were analyzed. Data were analyzed using Univariate and Tukey`s, Bonneferroni tests (α = 0.05). Two-parameter Weibull modulus, scale (m) and shape (0) were calculated. Test method (p < 0.001) and substrate type (p < 0.001) significantly affected the results. When testing adhesion of resin composite to enamel, SBT (25.9 ± 5.7)^a, TBT (17.3 ± 5.1)^a,c and μSBT (27.2 ± 6.6)^a,d test methods showed significantly higher mean bond values compared to μTBT (10.1 ± 4.4)^b (p < 0.05). Adhesion of resin composite to dentin did not show significant difference depending on the test method (12 ± 5.7–20.4 ± 4.8; p > 0.05). Only with SBT, significant difference was observed for bond values between enamel (25.9 ± 5.7) and dentin (12 ± 5.7; p < 0.05). Weibull distribution presented the highest shape values for enamel-μSBT (29.7) and dentin-μSBT (22.2) among substrate-test combinations. Regardless of the test method, cohesive failures in substrate were more frequent in enamel (19.1%) than in dentin (9.8%).     

Improvement in Dispersion of Phosphate Pigments Modified by Functionalized Graphite Nanoplatelets and Its Influence on Epoxy Coating Adhesion

Tripolyphosphate corrosion inhibitor was modified by functionalized graphite nanoplatelets to obtain a hybrid nanoparticle (functionalized graphite nanoplatelets–tripolyphosphate) with homogenous dispersion in epoxy coating. The effect of functionalized graphite nanoplatelets–tripolyphosphate dispersion on adhesion and anticorrosion behavior was discussed. Characterization analyses of the hybrid nanoparticle were performed by Fourier transform-infrared spectroscope, scanning electron microscope, and transmission electron microscope. Tripolyphosphate was linked to functionalized graphite nanoparticles by hydrogen bondings. Different epoxy coatings formulated with 1 wt% of functionalized graphite nanoplatelets, functionalized graphite nanoplatelets–tripolyphosphate, and tripolyphosphate were evaluated. Results showed, compared to traditional phosphate pigments, the adhesion of functionalized graphite nanoplatelets–tripolyphosphate epoxy coating and its anticorrosion behavior were significantly increased with the lowest loadings amounts.     

Adsorption of Proteins and Cell Adhesion to Plasma Treated Polymer Substrates

Plasma treatment is often used to alter cell interaction with polymer surfaces used in biomedical application. The influence of surface hydrophilicity/hydrophobicity on human mammary epithelial cell (HMEC) proliferation and adhesion of protein albumin to plasma treated polystyrene (PS) was studied. The PS surface was made hydrophilic or hydrophobic by treatment either in O₂ or CF₄ plasma. The rate of protein adhesion was studied by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) after incubation of PS in albumin solution for different periods, while cell viability and morphology was studied by MTT assay and scanning electron microscope (SEM). XPS measurements have shown that the quantity of adsorbed protein was higher for both plasma treated samples than for the untreated one. No significant difference regarding protein adhesion on hydrophilic or hydrophobic plasma treated surface was found by XPS. Contrary, the results for cell proliferation showed much better proliferation on hydrophilic surface.     

热处理对Ni-P镀层内应力及结合强度的影响

采用薄片弯曲法和压痕法分别研究了热处理温度对化学镀镍层的内应力以及镀层与基体的结合强度的影响规律。结果表明 :镀层的内应力为拉应力 ;当热处理温度为 2 0 0℃时 ,内应力减小 ,镀层经过 30 0、4 0 0或 6 0 0℃热处理 ,内应力逐步增大。随热处理温度升高 ,镀层与基体的结合力增大     

Adhesion of Styrene-Butadiene and Silicons Elastomers to Rigid Substrates at Quasi-Equilibrium

Adhesion threshold values for elastomers (SBR or silicone) in contact with rigid substrates (glass or polycarbonate) are obtained from the Johnson, Kendall and Roberts' test. The energy W_F involved in the formation of the contact at quasi-equilibrium shows no significant effect of the molecular weight of the elastomer. Moreover, W_F is of the same order of magnitude as the reversible energy of adhesion W_O. On the contrary, the energy W_R at quasi-equilibrium after forced contact depends on the molecular weight between crosslinks. However, the dependence is not universal for the different elastomers considered. It has not yet been possible to find the characteristics of the network which are responsible for the observed behaviours     

The Mechanism of Adhesion of Phenol-Formaldehyde Resins to Cellulosic and Lignocellulosic Substrates

The mechanism of adhesion of phenolic resins to cellulosic and lignocellulosic fibers has been explored using a nonpolymerizable bromine-labelled benzyl alcohol as a model for the adhesive. Bromine analysis by neutron activation techniques is sufficiently sensitive to show that reaction occurs much more extensively with the lignified fibers. This is attributed to the formation of covalent linkages between the model adhesive and the guaiacyl units in the lignin. The excellent general performance of phenolic adhesives on cellulose and lignocellulosic substrates can therefore be in part ascribed to the existence of high enthalpy covalent chemical bonds between adherend and adhesive.     

Adhesion of polyimides to metal and ceramic surfaces: an overview

Experimental and theoretical results on polyimide-to-metal and -ceramic adhesion are briefly reviewed. In general, the polyimide-on-metal interfaces have stronger interactions vis-a-vis the metal-on-polyimide interfaces. A section is also devoted to adhesion promoters and their effect on the adhesion. Data from the literature imply that one of the reasons for the improvement in adhesion in the case of the polyimide-on-silicon oxide interface using a y-aminopropyltriethoxysilane adhesion promoter is physical in nature. With the adhesion promoter the interfacial region within the polyimide is likely to be less oriented and more entangled than the same system without the adhesion promoter. This subtle effect is illustrative of the understanding that can result from careful locus-of-failure analysis in an adhesion study.