A fuzzy optimization model for planning integrated terrestrial carbon management networks

Clean Technologies and Environmental Policy - Biochar application and enhanced weathering are negative emission technologies (NETs) with the potential for large-scale deployment for the removal of...     

The role of biodegradation in limiting the accumulation of petroleum hydrocarbons in raingarden soils

Previous studies have indicated that raingardens are effective at removing petroleum hydrocarbons from stormwater. There are concerns, however, that petroleum hydrocarbons could accumulate in raingarden soil, potentially resulting in liability for the site owner. In this work, 75 soil samples were collected from 58 raingardens and 4 upland (i.e., control) sites in the Minneapolis, Minnesota area, representing a range of raingarden ages and catchment land uses. Total petroleum hydrocarbon (TPH) concentrations in the samples were quantified, as were 16S rRNA genes for Bacteria and two functional genes that encode for enzymes used in the degradation of petroleum hydrocarbons. TPH levels in all of the raingarden soil samples were low (<3 μg/kg) and not significantly different from one another. The TPH concentration in raingarden soil samples was, however, significantly greater (p ≤ 0.002) than TPH levels in upland sites. In addition, the number of copies of Bacteria 16S rRNA genes and functional genes were greater in the raingardens planted with deeply-rooted natives and cultivars than in raingardens containing simply turf grass or mulch (p < 0.036), suggesting that planted raingardens may be better able to assimilate TPH inputs. The ability of microorganisms present in the soil samples to degrade a representative petroleum hydrocarbon (naphthalene) was also investigated in batch experiments. A sub-set of the field sites was selected for re-sampling, and all soil samples tested (n = 8) were able to mineralize naphthalene. In these experiments the initial mineralization rate correlated with the number of copies of Bacteria 16S rRNA genes present.     

On the hazard of quiet vehicles to pedestrians and drivers

The need to produce more efficient and less polluting vehicles has encouraged mass production of alternative energy vehicles, such as hybrid and electric cars. Many of these vehicles are capable of very quiet operation. While reducing noise pollution is desirable, quieter vehicles could negatively affect pedestrian safety because of reduced sound cues compared to louder internal combustion engines. Three studies were performed to investigate people's concern about this issue. In Study 1, a questionnaire completed by 378 people showed substantial positive interest in quiet hybrid and electric cars. However, they also indicated concern about the reduced auditory cues of quiet vehicles. In Study 2, 316 participants rated 14 sounds that could be potentially added to quiet alternative-energy vehicles. The data showed that participants did not want annoying sounds, but preferred adding “engine” and “hum” sounds relative to other types of sounds. In Study 3, 24 persons heard and rated 18 actual sounds within 6 categories that were added to a video of a hybrid vehicle driving by. The sounds most preferred were “engine” followed by “white noise” and “hum”. Implications for adding sounds to facilitate pedestrians' detection of moving vehicles and for aiding drivers' awareness of speed are discussed.     

Response Surface Designs for Experiments with Mixtures

In estimating a response surface where the k variables represent proportions in a mixture, the experimenter is often interested in a reasonably well-defined region of interest which may, for example, center about current operating levels. Previously developed designs are difficult to use except in exploring the entire factor space, and even then there are several disadvantages to these designs. A general method of constructing designs from familiar response surface designs in k ? 1 independent variables and the appropriate analysis for a general polynomial is given. Special attention is given to the first and second order polynomials.     

Feasible compositions for random copolymerizations

Using the attainable region approach, feasible compositions and conversions for random copolymers are determined, along with altermatives for the related reactor configurations. This analysis attempts to find all of the possible compositions that can be produced by any system of reactros and mixing. The average copolymer compositions are bounded by the feed composition and the instantaneous copolymer composition produced at the initial conditions. Since the instantaneous copolymer composition can be found through the Mayo‐Lewis equation, that case and the feed composition mark the limiting feasible compositions. The results can also be used to determine the range of feed compositions for which a specific copolymer product composition is possible. If the addition of monomer at any point in the reactor system is possible, e.g., by side‐feeding, the analysis indicates that any desired copolymer composition can be obtained.     

Hydrodeoxygenation of HMF over Pt/C in a continuous flow reactor

The three‐phase hydrodeoxygenation reaction of 5‐hydroxymethylfurfural (HMF) with H₂ was studied over a 10 wt % Pt/C catalyst using both batch and flow reactors, with ethanol, 1‐propanol, and toluene solvents. The reaction is shown to be sequential, with HMF reacting first to furfuryl ethers and other partially hydrogenated products. These intermediate products then form dimethyl furan (DMF), which in turn reacts further to undesired products. Furfuryl ethers were found to react to DMF much faster than HMF, explaining the higher reactivity of HMF when alcohol solvents were used. With the optimal residence time, it was possible to achieve yields approaching 70% in the flow reactor with the Pt/C catalyst. Much higher selectivities and yields were obtained in the flow reactor than in the batch reactor because side products are formed sequentially, rather than in parallel, demonstrating the importance of choosing the correct type of reactor in catalyst screening. © 2014 American Institute of Chemical Engineers AIChE J, 61: 590–597, 2015     

Examination of radio‐opacity enhancing additives in shape memory polyurethane foams

Three microparticle additives, tungsten (W), zirconium oxide (ZrO₂) , and barium sulfate (BaSO₄) were selected to enhance the radio‐opacity in shape memory polymer (SMP) foam biomaterials. The addition of filler causes no significant alterations of glass transition temperatures, density of the materials increases, pore diameter decreases, and total volume recovery decreases from approximately 70 times in unfilled foams to 20 times (4% W and 10% ZrO₂). The addition of W increases time to recovery; ZrO₂ causes little variation in time to shape recovery; BaSO₄ increases the time to recovery. On a 2.00 mean X‐ray density (mean X.D.) scale, a GDC coil standard has a mean X.D. of 0.62 ; 4% W enhances the mean X.D. to 1.89, 10% ZrO₂ to 1.39 and 4% BaSO₄ to 0.74. Radio‐opacity enhancing additives could be used to produce SMP foams with controlled shape memory kinetics, low density , and enhanced X ‐ray opacity for medical materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42054.     

Bridging the Gap between Quantitative and Qualitative Accelerated Life Tests

Test planners have long sought the ability to incorporate the results of highly accelerated life testing (HALT) into an early estimate of system reliability. While case studies attest to the effectiveness of HALT in producing reliable products, the capability to translate the test's limited failure data into a meaningful measure of reliability improvement remains elusive. Further, a review of quality and reliability literature indicates that confusion exists over what defines a HALT and how HALT differs from quantitative accelerated life testing methods. Despite many authors making a clear distinction between qualitative and quantitative accelerated life tests, an explanation as to why this delineation exists cannot be found. In this paper, we consider an exemplary HALT composed of a single stressor to show that the HALT philosophy precludes the estimation of a system's hazard rate function parameters because of the test's fix implementation strategy. Four common accelerated failure data analysis methods are highlighted to show their limitations with respect to estimating reliability from HALT data. Finally, a modified accelerated reliability growth test is proposed as a way forward for future research in HALT scenarios to characterize the risk of attaining a reliability requirement and improve parameter estimation. Copyright © 2014 John Wiley & Sons, Ltd.     

Matching housing supply and demand: an empirical study of Hong Kong's market

This paper has the objective of improving on the issue of forecasting new housing construction, and highlights differences between space demand and investment demand in housing markets. Further, it indicates how these differences will affect construction decisions. The first step is to identify the factors associated with estimating residential property prices in Hong Kong, based on a demand-supply adjustment process. Specifically, this study examines the role of population growth, transaction volume, inflation and interest rate in determining house prices. Second, based on these estimations, a methodology is developed to estimate the investment demand schedule and new construction of residential property.