Design of cost-effective Fe-based amorphous coating alloys having high amorphous forming ability by thermodynamic calculation

In this study, new cost-effective Fe-based amorphous coating alloys having high amorphous forming ability were developed by varying the Fe content, while their microstructure, hardness, and corrosion resistance were also evaluated. Chemical compositions that have the lowest driving force of formation of crystalline phases such as Fe₃P, Fe₃C, and α-Fe were obtained from thermodynamically calculated phase diagrams of the representative Fe_xAl₂(P_10.83C_7.47B_1.7)_98-x alloy system at a crystallization temperature of 443 °C. Considering the intersections of driving force curves of Fe₃P and Fe₃C, Fe₃P and α-Fe, and Fe₃C and α-Fe, the Fe contents were found to be 77.8, 76.2, and 75.8 at.%, respectively. The microstructural analysis results of 1.5-mm-diameter suction-cast Fe-based alloys indicated that the Fe_76.5Al₂(P_10.83C_7.47B_1.7)_21.5 alloy had a fully amorphous microstructure, whereas crystalline phases were formed in other alloys. This alloy showed a better hardness and corrosion resistance than conventional thermal spray coating alloys, and its production cost could also be reduced by using less expensive alloying elements, which could provide a good way to practically apply this alloy to Fe-based amorphous thermal spray coatings.     

Highly ordered bilayer structures of gold(I)–alkanethiolates having two types of alkyl groups

The luminescent gold(I)–alkanethiolates containing two types of alkyl groups, Au(I)–(SR)_x(SR′)_ys, were synthesized by mixing HAuCl₄ with two n-alkanethiols in tetrahydrofuran. Au(I)–(SR)_x(SR′)_ys have highly ordered bilayer structures and the dominant conformations of the alkyl groups were found to be all-trans from X-ray diffraction and FT-IR spectroscopy studies. The gold nanoparticles stabilized by two types of alkanethiolates could be prepared by reducing the Au(I)–(SR)_x(SR′)_ys using tetrabutylammonium borohydride (TBABH) as a reducing agent. Elemental analysis results of Au(I)–(SR)_x(SR′)_ys and gold nanoparticles prepared from Au(I)–(SR)_x(SR′)_ys indicated that the longer alkanethiols are more reactive for the formation of Au(I)–(SR)_x(SR′)_ys and also the longer alkylthiolates are preferentially absorbed on the gold particles compared with the shorter ones.     

Cycling performance of a lithium-ion polymer cell assembled by in-situ chemical cross-linking with fluorinated phosphorous-based cross-linking agent

Lithium-ion polymer cells composed of a carbon anode and a LiCoO₂ cathode are assembled with a gel polymer electrolyte cured by in-situ chemical cross-linking with novel cross-linking agents. The strong interfacial adhesion between the electrodes and the porous polyethylene membrane by the chemical cross-linking results in the stable capacity retention of the cell. However, a reduction in the ionic mobility in both the electrolyte and the electrodes adversely affects the high rate performance of the cell. These results imply that proper control of the cross-linking density in the cell is imperative for achieving good capacity retention and high rate performance of the cell.     

Mixing–segregation phenomena of binary system in a fluidized bed

A study on mixing–segregation phenomena in a gas fluidized bed of binary density system was performed by analysis of the residence time distribution and mixing degree. The effect of particle mixing on the residence time distribution and solid mixing was studied in a binary particle system with different densities. Residence time distribution curve and mean residence time of each particle were measured according to the flotsam particle size, mixing ratio and gas velocity in a gas fluidized bed (0.109 m I.D., 1.8 m height). The characteristics of residence time distribution and the deviation of mean residence time of each particle are consistent with previous mixing index based on the axial concentration of jetsam. From this study, mixing index of binary particle system with different densities should be considered by not only axial concentration distribution of jetsam particle but also characteristics of residence time distribution. This result suggests that the solid movement by fluidization gas is more important than solid axial dispersion.     

Continuous photo-fermentative hydrogen production from lactate and lactate-rich acidified food waste

In the present work, a continuous photo-fermentative hydrogen (H₂) production from lactate was attempted at various hydraulic retention times (HRTs) (48–120 h). Electron balance was made at each operating conditions to elucidate different performances. At 120 h HRT, H₂ production was negligible, while 42% and 52% of substrate electrons diverted towards cell growth and soluble microbial products (SMPs), respectively. After changing HRT to 96 h, H₂ yield jumped to 2.3 mol-H₂/mol-lactate_added with less SMPs production and minimal cell growth. The highest H₂ production rate of 260 mL-H₂/L-fermenter/d was also achieved at 96 h HRT. When HRT was further shortened to 72 and 48 h, H₂ yield dropped to 1.4 and 0.2 mol-H₂/mol-lactate_added, respectively. While almost all of the lactate was degraded at <72 h HRT, only 65% of the lactate was consumed at 48 h HRT. From 200th day, the feedstock was changed to lactate-rich acidified food waste, which was obtained via one-day fermentation of food waste and subsequent centrifugation. At 2 g chemical oxygen demand/L, substrate conversion efficiency reached 35%, which was slightly lower than that of feeding pure lactate. SMPs were found to be mainly consisted of low molecular weight compounds (<500 Da), and the majority of organic matters were aromatic proteins at 120 h HRT and it was shifted to humic-like region in 96 h HRT.     

Phosphorus load estimation in the Saginaw River, MI using a Bayesian hierarchical/multilevel model

We propose the use of Bayesian hierarchical/multilevel ratio approach to estimate the annual riverine phosphorus loads in the Saginaw River, Michigan, from 1968 to 2008. The ratio estimator is known to be an unbiased, precise approach for differing flow-concentration relationships and sampling schemes. A Bayesian model can explicitly address the uncertainty in prediction by using a posterior predictive distribution, while in comparison, a Bayesian hierarchical technique can overcome the limitation of interpreting the estimated annual loads inferred from small sample sizes by borrowing strength from the underlying population shared by the years of interest. Thus, by combining the ratio estimator with the Bayesian hierarchical modeling framework, long-term loads estimation can be addressed with explicit quantification of uncertainty. Our study results indicate a slight decrease in total phosphorus load early in the series. The estimated ratio parameter, which can be interpreted as flow-weighted concentration, shows a clearer decrease, damping the noise that yearly flow variation adds to the load. Despite the reductions, it is not likely that Saginaw Bay meets with its target phosphorus load, 440 tonnes/yr. Throughout the decades, the probabilities of the Saginaw Bay not complying with the target load are estimated as 1.00, 0.50, 0.57 and 0.36 in 1977, 1987, 1997, and 2007, respectively. We show that the Bayesian hierarchical model results in reasonable goodness-of-fits to the observations whether or not individual loads are aggregated. Also, this modeling approach can substantially reduce uncertainties associated with small sample sizes both in the estimated parameters and loads.     

The Effects of Portland's Urban Growth Boundary on Housing Prices

Unlike previous studies, which used metropolitan level data, this study uses spatially disaggregated data (block group data from the U.S. Census) to statistically test the effects of Portland's urban growth boundary (UGB) on housing prices. This analysis shows no evidence of a significant difference between housing prices inside and outside the UGB, suggesting that both inside and outside the UGB are parts of a single housing market.     

The use of self checks and voting in software error detection: anempirical study

The results of an empirical study of software error detection using self checks and N-version voting are presented. Working independently, each of 24 programmers first prepared a set of self checks using just the requirements specification of an aerospace application, and then each added self checks to an existing implementation of that specification. The modified programs were executed to measure the error-detection performance of the checks and to compare this with error detection using simple voting among multiple versions. The analysis of the checks revealed that there are great differences in the ability of individual programmers to design effective checks. It was found that some checks that might have been effective failed to detect an error because they were badly placed, and there were numerous instances of checks signaling nonexistent errors. In general, specification-based checks alone were not as effective as specification-based checks combined with code-based checks. Self checks made it possible to identify faults that had not been detected previously by voting 28 versions of the program over a million randomly generated inputs. This appeared to result from the fact that the self checks could examine the internal state of the executing program, whereas voting examines only final results of computations. If internal states had to be identical in N-version voting systems, then there would be no reason to write multiple versions