Integration of RP and explicit dynamic FEM for the visualization of the sheet metal forming process

This paper develops a FORTRAN program to convert the explicit dynamic finite element method (FEM)-simulated deformed sheet to the stereolithography (STL) format used in the rapid prototyping (RP) apparatus. Such integration of the RP/FEM can rapidly produce a visualized 3D physical part of the sheet deformation state. Three cases – cylindrical drawing, bore expanding and square cup drawing processes, simulated by explicit dynamic FEM – were investigated to verify the integration system. The wrinkled flange in the cylindrical drawing process, the circle hole expansion in the bore expanding process, and the square cup in the square cup drawing were successfully predicted by explicit dynamic FEM, and the rapid prototyping 3D physical parts also showed good visualization of the deformed sheet for the above three cases. It proves that the integration system of RP/FEM will be able to supply a useful method for the visualization of the 3D physical part in the sheet metal forming process.     

Effect of biometric flow channel on the power generation at different Reynolds numbers in the single chamber of rumen microbial fuel cells (RMFCs)

Microbial fuel cells (MFCs) represent a completely new method of renewable energy recovery. The purpose of this work is to study the effect of biometric flow channels on the power performance in the single rumen microbial fuel cells (RMFCs) at different Reynolds numbers. Experiments in a circulation system were executed by using a double two-inlet Y-type inlet channel and connecting it with the RMFCs. Some results that were found from the numerical simulation and experiment are addressed as follows: First, the biometric flow channel would create a more uniform flow field with obstacles than one without, regardless of the Reynolds number. Second, an extra voltage output of 0.2 V, based on the example without obstacles, was provided as in the case of one with. This further explains the design of biometric flow channels having a greater, more positive effect on power performance. Finally, these observations can provide more information on realizing the mechanism of MFCs dynamic reactions and further enhance power performance.     

Effects of fumarate on ruminal ammonia accumulation and fiber digestion in vitro and nutrient utilization in dairy does

The objective of this study was to evaluate effects of fumarate on ruminal ammonia accumulation and fiber digestion in vitro and on feed intake and nutrient utilization in dairy does. Batch cultures of mixed rumen microorganisms were used to study effects of different concentrations of fumarate on fermentation with various N sources (ammonia as ammonium bicarbonate, casein amino acids, casein peptides, gelatin peptides) and feeds (bermudagrass hay, mixed diet of 60% bermudagrass hay plus 40% concentrate) for 6 and 24 h, respectively. Substrates were grouped into pairs for separate incubations. Monosodium fumarate was added to incubation tubes to achieve final concentrations of 0, 5, and 10 mM fumarate. More ammonia accumulated at the end of incubation with added ammonium bicarbonate. Ammonia concentration was higher for peptide compared with amino acid incubation, and for casein peptide compared with gelatin peptide. Addition of fumarate linearly decreased ammonia for all N sources and for feed substrates. For all substrate types, fumarate treatment increased acetate, propionate, and total volatile fatty acids (VFA), decreased acetate to propionate ratio, and tended to reduce branched-chain VFA. Digestion of feed neutral detergent fiber (NDF) by rumen microorganisms was improved by fumarate along with elevated endoglucanase and xylanase activities. In an animal metabolism experiment, 8 dairy does (4 per treatment) were used in a completely randomized design for 21 d. Does were fed a hay plus concentrate diet without (control) or with fumarate (6 g/head per day) supplementation to determine feed intake, whole-tract nutrient digestibility, and N utilization. Fumarate treatment did not affect weight change or feed intake but increased whole-tract digestion of gross energy, crude protein, and cellulose. Digested N was increased by fumarate supplementation; however, N retention was unaffected. Plasma glucose concentration was elevated with fumarate but urea N concentration remained unchanged. Fumarate addition had significant effects on rumen microbial fermentation by decreasing ammonia and branched-chain VFA, and by increasing acetate and propionate, and NDF digestion. These effects were reflected in the improvement in whole-tract gross energy, crude protein, and cellulose digestion and elevated plasma glucose concentration when dairy does were supplemented with fumarate.     

Effect of heat treatments on the essential oils of kumquat (Fortunella margarita Swingle)

Kumquats (Fortunella margarita Swingle) cultivated in Taiwan are eaten raw or made into candied fruit or fruit tea. For the experiments described in this paper, essential oils were obtained from kumquat peels or whole fruit by cold pressing, steam distillation or heating in water at 90 °C for 15 min followed by steam distillation. The volatile components contained in the essential oils were identified by direct injection (DI) or headspace-solid phase microextraction (HS-SPME) coupled with gas chromatography (GC). A total of 43 compounds were identified, of which 37 were verified by DI/GC and 31 by HS-SPME/GC. Hot water heating increased the yields of essential oils from both peels and whole fruit. The principal constituents of the oils were similar except for the minor compounds, including linalool, terpinen-4-ol and α-terpineol, the levels of which increased after steam distillation. The whole fruit also contained higher levels of terpene alcohols.     

Study of ductile fracture and preform design of upsetting process using adaptive network fuzzy inference system

This paper combines adaptive-network-based inference system (ANFIS) and elasto-plastic finite element to predict the ductile fracture initiation and the preform shape of the upsetting process. From the hybrid-learning algorithm in ANFIS, it can efficiently construct rule database and optimal distribution of membership function to solve the punch stroke which causes the ductile fracture, and the preform shape which results a desired cylindrical workpiece after forming in the upsetting process. As a verification of this system, the punch stroke for ductile fracture initiation and the free boundary radius of the billet after forming are compared between ANFIS and FEM simulated results. In the ductile fracture prediction, it is proved that ANFIS can efficiently predict the ductile fracture initiation successfully for arbitrary friction coefficient and aspect ratio. In the preform shape prediction, the simulated cylindrical radius shows good coincidence with the desired radius after forming. From this forward and inverse investigation, the ANFIS is proved to supply a useful optimal soft computing approach in the forming category.     

Influence of solfonated melamine formaldehyde condensate on the quality of building blocks production by extrusion of cement–clay pastes

The extrusion of cement–clay pastes to manufacture building blocks by cold stabilization of clays by cement is investigated. Based on the pressure and the torque values measured during paste preparation and extrusion, an operative window of concentration of water and sulphonated melamine formaldehyde (SMF) fluidizer suitable to obtain simple and complex building blocks is identified: for pastes with clay/cement ratio 2.6:1 the water content ranges between 24% and 29% w/w for 6% w/w SMF and between 29% and 33% for 0% w/w SMF. Extruded items have been submitted to bending stress resistance tests to evaluate the mechanical properties of clay stabilized by cement and to identify the paste formulations with the highest resistances. To the best a 25% increase in mechanical properties is achieved by applying a curing treatment at 35 °C and 90% humidity for 96 h. However based on the results of tests of frost resistance and resistance to water contact, the clay–cement blocks do not offer so far an alternative to conventional bricks.     

Low-frequency damping properties of as-extruded Mg-11.2Li-0.95Al-0.43Zn magnesium alloy

Low-frequency damping capacities of as-extruded Mg-11.2Li-0.95Al-0.43Zn (LAZ1110) alloy are studied by dynamic mechanical analysis tests. Experimental results reveal that it is β-phase matrix with α precipitates in major. The heating internal friction Q⁻¹(T) curves show P₁, P₂ and P₃ peaks appearing at 30 °C, 107 °C and 215 °C, respectively, and P₁ and P₂ peaks have been reported, but P₃ peak has not yet. P₁ and P₂ peaks are frequency-dependent and their activation energies are calculated as 0.85 eV and 1.02 eV, respectively. The heating Q⁻¹(T) curves also show a significant high-temperature damping background (HTDB) at temperature above 275 °C and its activation energy is calculated as 0.75 eV which is relatively low due to the abundant α/β phase boundaries. XRD tests indicate that the textures are developed during recrystallization and grain growth of the heated specimens and the texture development is suggested to be closely related to the occurrence of P₃ peak.     

Purine Content in Grass Shrimp during Storage as Related to Freshness

In grass shrimp ( Penaeus monodon ), the combined total content of the uricogenic bases adenine (Ade) and hypoxanthine (Hyp) decreased gradually during storage. Whether stored at 5°C or at room temperature (22°C), a negative regression of log Ade and a positive regression of the Kp value (Hyp/Ade) were observed. Volatile basic nitrogen (VBN) increased during storage at 5°C and 22°C. Correlations between the content of log Ade and VBN at 5°C and 22°C were –0.9248 (p<0.01) and –0.8139 (p<0.05, while those between the Kp value and VBN were 0.9557 (p<0.001) and 0.8197 (p<0.05), respectively. At the point where the shrimp would remain acceptable, the upper limits of Kp were 1.42 and 1.29 for storage at 5°C and 22°C, respectively; the corresponding lower limits of Ade were 18.72 and 20.42 μmole/g dry wt.