The application of neural networks to fuel processors for fuel-cellvehicles

Passenger vehicles fueled by hydrocarbons or alcohols and powered by proton exchange membrane (PEM) fuel cells address world air quality and fuel supply concerns while avoiding hydrogen infrastructure and on-board storage problems. Reduction of the carbon monoxide concentration in the on-board fuel processor's hydrogen-rich gas by the preferential oxidizer (PrOx) under dynamic conditions is crucial to avoid poisoning of the PEM fuel cell's anode catalyst and thus malfunction of the fuel-cell vehicle. A dynamic control scheme is proposed for a single-stage tubular cooled PrOx that performs better than, but retains the reliability and ease of use of, conventional industrial controllers. The proposed hybrid control system contains a cerebellar model articulation controller artificial neural network in parallel with a conventional proportional-integral-derivative (PID) controller. A computer simulation of the preferential oxidation reactor was used to assess the abilities of the proposed controller and compare its performance to the performance of conventional controllers. Realistic input patterns were generated for the PrOx by using models of vehicle power demand and upstream fuel-processor components to convert the speed sequences in the Federal Urban Driving Schedule to PrOx inlet temperatures, concentrations, and flow rates. The proposed hybrid controller generalizes well to novel driving sequences after being trained on other driving sequences with similar or slower transients. Although it is similar to the PID in terms of software requirements and design effort, the hybrid controller performs significantly better than the PID in terms of hydrogen conversion setpoint regulation and PrOx outlet carbon monoxide reduction     

DRYING OF SOY PULP (OKARA) IN A BED OF INERT PARTICLES

Drying of okara, an insoluble pulp residue waste byproduct of tofu production, was investigated in a continuously moving bed of inert particles subjected to vortex-like motion. The experimental variables in their respective ranges included the mass of Teflon pellets used as inert particles (0.4-1.2 kg), feed rate (0.5-1.4 kg/h), inlet air temperature (100-145°C) and airflow rate (195-271 m³/h). The dryer showed good performance in general and produced dry okara with moisture content ranging from 5 to 33% wb depending upon the operating conditions. The product recovery ranged from 80 to 90% on dry basis in most experiments. The specific water evaporation rate in okara drying increased with increasing of the feed rate and mass of Teflon pellets. However, the specific heat consumption decreased with an increase in the okara feed rate. Results showed that specific heat consumption for okara drying in a bed of inert particles was about 3 to 4 times higher in comparison with that of free water.     

Impact of appearance on degree of liking and eating quality expectations of selected apple cultivars

This study investigated the effect of taste expectations based on cultivar recognition on the preference for apple‐eating quality. Consumer preference for eating quality was assessed using three levels of product information, viz. (i) no visual information, (ii) a photograph depicting the typical appearance of the specific cultivar and (iii) an incorrect photograph, misleadingly depicting a different cultivar. Consumers scored the eating quality of ‘Pink Lady^?’ served with the correct photograph significantly higher compared with presentation without pictorial information, suggesting a positive image for this trademark cultivar. Conversely, consumers had lower eating quality expectations for ‘Starking’ and ‘Golden Delicious’ indicated by lower scores when supplied with matching photos. Cultivar developers and researchers should be mindful of the confounding effect of fruit appearance on the hedonic assessment of eating quality. The order of presentation (matching or wrong photograph first) affected the preference scores and should be considered in future studies.     

Effects of raw material particle size distribution on the characteristics of Scots pine sawdust fuel pellets

In order to study the influence of raw material particle size distribution on the pelletizing process and the physical and thermomechanical characteristics of typical fuel pellets, saw dust of Scots pine was used as raw material for producing pellets in a semi industrial scaled mill (∼ 300 kg h^− 1). The raw materials were screened to a narrow particle size distribution and mixed into four different batches and then pelletized under controlled conditions. Physical pellet characteristics like compression strength, densities, moisture content, moisture absorption and abrasion resistance were determined. In addition, the thermochemical characteristics, i.e. drying and initial pyrolysis, flaming pyrolysis, char combustion and char yield were determined at different experimental conditions by using a laboratory-scaled furnace. The results indicate that the particle size distribution had some effect on current consumption and compression strength but no evident effect on single pellet and bulk density, moisture content, moisture absorption during storage and abrasion resistance. Differences in average total conversion time determined for pellet batches tested under the same combustion conditions was less than 5% and not significant.     

Characterization,liquid crystalline behavior,optical and electrochemical study of new aliphatic–aromatic polyimide with naphthalene and perylene subunits

A new aliphatic–aromatic diamine with naphthalene diimide (DA) moiety and a polyimide with naphthalene and perylene diimide subunits (PI) were synthesized and their thermotropic liquid crystalline behavior was examined by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Both compounds exhibited liquid crystalline properties. The temperatures of 5% weight loss (T_5%) of the diamine and polyimide range from 350 to 373 °C in nitrogen. The optical properties, that is, UV–vis absorption and photoluminescence (PL) of obtained monomer and polyimide were studied in solution and in solid state as a blend with inert poly(methyl methacrylate) (PMMA). Influence of solvent polarity, excitation wavelength and concentration on DA and PI emission was found. The investigated compounds emitted green light in chloroform solution. Relative PL intensity of the DA and PI was investigated in NMP in relation to rhodamine-B used as a standard. The electrochemical behavior of diamine and polyimide was studied (in solution) by differential pulse voltammetry (DPV). The HOMO and LUMO levels of these compounds were in the range of ?5.44 to ?6.03 eV and ?3.81 eV, respectively. Energy gap (E_g) values were calculated using cyclic voltammetry (CV) and UV–vis measurements. Introduction of a perylene moiety (PI) resulted in increase of E_g (2.22 eV) compared to DA which exhibited a E_g value of approximately 1.63 eV. The electrical properties of DA and PI were investigated by current–voltage (I–V) measurements on ITO/compound/Al devices.     

A review of the stability of disconnected equilibrium capillary surfaces

A disconnected free surface consists of several separate pieces (connectivity components). The connectivity components and solid walls bound a connected liquid region. Generally, the stability problem for such equilibrium configurations cannot be simply reduced to a set of independent problems for each connectivity component. Rather, the set of connectivity components, the solid walls and the connected liquid region must be considered simultaneously. In this review, we outline particular properties of the stability of mechanical equilibrium of systems with disconnected free surfaces and summarize the results of previous work. Several open problems are also discussed.     

Generation of porous particle structures using the void expansion method

The newly developed “void expansion method” allows for an efficient generation of porous packings of spherical particles over a wide range of volume fractions using the discrete element method. Particles are randomly placed under addition of much smaller “void-particles”. Then, the void-particle radius is increased repeatedly, thereby rearranging the structural particles until formation of a dense particle packing. The structural particles’ mean coordination number was used to characterize the evolving microstructures. At some void radius, a transition from an initially low to a higher mean coordination number is found, which was used to characterize the influence of the various simulation parameters. For structural and void-particle stiffnesses of the same order of magnitude, the transition is found at constant total volume fraction slightly below the random close packing limit. For decreasing void-particle stiffness the transition is shifted towards a smaller void-particle radius and becomes smoother.     

RC Slabs Strengthened with Prestressed and Gradually Anchored CFRP Strips under Monotonic and Cyclic Loading

This paper presents the test results of reinforced concrete slabs strengthened with prestressed and gradually anchored carbon fiber–reinforced polymer (CFRP) strips under monotonic and cyclic loading. To take full advantage of the externally bonded CFRP technique, it is beneficial to apply the laminates in a prestressed state, which relieves the stress in the steel reinforcement and reduces crack widths and deflection. The aim of the monotonic tests was to determine the strengthening efficiency of the new prestressing technique and to investigate serviceability and ultimate states. The cyclic tests were performed to identify the fatigue behavior of the strengthened slabs and to investigate the influence of long-term cyclic loading and elevated temperature on the bond properties of the prestressed CFRP laminates and the ductility and flexural strength of the strengthened slabs. A nonlinear analytical model of reinforced concrete members strengthened with passive and prestressed CFRP strips under static loading is proposed in the paper. A comparison of the experimental and predicted results reveals an excellent agreement in the full range of loading.