A generation method of artificial fluctuation data of wind power output considering smoothing effect

To use realistic wind power fluctuation data is important in simulating frequency change of power systems. It is well known that the smoothing effect must be taken into account when generating the artificial wind power output. Therefore, this paper proposed a new method to generate fluctuation waveform considering smoothing effect based on random number to fulfill the correlation among multiple sites and autoregression model. The effectiveness of the proposed method was tested by using practical wind speed data measured in Tohoku district.     

Joint Learning in Innovative R&D Collaboration

The present study analyzes the mechanisms and facilitators behind joint learning in R&D collaborations by way of a qualitative comparative case study analyzing three supplier relationships and three internal R&D partnerships of the focal organization. The results suggest a single joint learning process for internal and external relationships in which the role of the customer and the facilitation of the joint learning process vary depending on the context. Whereas the role of motivation is central for joint learning in the internal relationships, mutual trust is important to the external relationships.     

Optimization of the metakaolin geopolymer preparation for maximized ammonium adsorption capacity

Geopolymers are functional materials that can be used in various environmental applications such as adsorbents in pollutant removal from wastewaters. Metakaolin geopolymer (MK-GP) has been proven to be especially suitable for ammonium (NH₄ ⁺) removal. In this research, the optimal reagent and raw material ratios in the preparation of MK-GP in terms of NH₄ ⁺ adsorption capacity were investigated. The response surface methodology based on the face-centered central composite design was used to optimize the levels of three factors: the amounts of hydroxide, silicate, and metakaolin. In addition, the effect of Na or K as the charge-balancing cation was studied. Empirical models were fitted to the experimental data using multiple linear regression. The significance of the models was confirmed by means of analysis of variance. Optimal NH₄ ⁺ removal efficiency was achieved when the amounts of hydroxide and silicate were maximized, the amount of metakaolin was minimized, and Na-based reagents were used. These trends are most likely a result of optimized conversion of metakaolin into MK-GP.     

The association of distress and sleeping problems with physicians’ intentions to change profession: The moderating effect of job control.

The present study examined whether job control moderated the association between stress indicators (distress and sleeping problems) and intentions to change profession among 2,650 Finnish physicians. Ordinal logistic regression analysis was applied. The authors found that high levels of distress and sleeping problems were associated with higher levels of intentions to change profession, whereas high job control was associated with lower levels of intentions to change profession even after adjusting for the effects of gender, age, and employment sector. In addition, high job control was able to mitigate the positive association that distress and sleeping problems had with intentions to change profession. Our findings highlight the importance of offering more job control to physicians to prevent unnecessary physician turnover. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An experimental investigation into the pre-treatment of synthetic membranes using sodium hydroxide solutions

In this paper the effect of two pre-treatment methods are compared experimentally for the filtration of (i) a spent sulphite liquor (17.8 wt.% dry solids) using a 20 kg mol⁻¹ molar mass cut off (MMCO) fluoropolymer membrane and (ii) a molasses solution (45° Brix) using a polysulphone (Psf) membrane (1.5 μm pore size). Both feeds are industrially relevant, and subject to severe fouling issues when membranes are used in their subsequent processing. The pre-treatment methods evaluated were: (i) conditioning with water at 60 °C only [Protocol 1], and (ii) conditioning with water at 60 °C followed by cleaning with 0.5 wt.% NaOH [Protocol 2]. Results are presented that confirm the benefits of sodium hydroxide preconditioning upon performance, supporting the suggestion by some membrane manufacturers that this step be included as part of the pre-treatment protocol.     

Site managers’ daily work and the uses of building information modelling in construction site management

The use of building information modelling (BIM) and related software tools is increasingly expanding in the work of site managers in construction projects. The early uses of BIM in the actual tasks of site managers are explored by examining the utilization of BIM in their work and the challenges in the deployment of the new digital tools for traditional project collaboration. The ethnographic method of the study consists of shadowing the site managers’ work. The site managers actively used BIM and found it beneficial for their daily work. However, the use of BIM in construction sites is still limited because only a few managers have the competence to use BIM software tools, mobile tools are lacking, and the information content of the models needed for construction work is insufficient.     

Shape memory crosslinked polyurethanes containing thermoreversible Diels‐Alder couplings

Crosslinked polyurethanes (PUs) containing irreversible (allophanate) and reversible Diels‐Alder chemical bonds were synthesized using various diisocyanates (methylene diphenyl diisocyanate MDI, 1,6‐hexamethylenediisocyanate HDI) and poly(?‐caprolactone) ((PCL) with different molecular weights (M_n = 10 kg/mol, 25 kg/mol, 50 kg/mol) as diol component. The melting/crystallization of PCL and the reversible DA bonds acted as temperature‐activated switches for shape memory performances, while allophanate network provided the permanent crosslinks for these PUs. The reversible DA bonds were obtained by the reaction of diisocyanate‐ended prepolymers with furfurylamine (FA) followed by the addition of bismaleimide (BMI). The permanent crosslinks between the linear chains containing DA bonds were achieved using additional amounts of diisocyanates (MDI or HDI). The above reaction path was supported by infrared spectroscopic results and swelling experiments. Tensile mechanical and shape memory properties in tension of the PUs were determined and discussed as a function of composition and crosslink densities deduced from swelling and dynamic mechanical analysis. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44145.     

Selective preparation of oligomeric naphthylene ether and its applications to epoxy resin for silicon carbide power semiconductor device materials

In this study, a novel method for selective synthesis of naphthylene ether trimers by self‐condensation of 2,7‐dihydroxynaphthalene in the presence of catalytic amount of potassium hydroxide was reported. An epoxy resin from the trimers was prepared and properties of the cured epoxy resin were examined. The cured resin showed not only good physical thermal stability, such as high glass transition temperature and low thermal expansion coefficient, but also good chemical thermal stability like high thermal decomposition temperature. Additionally, low moisture absorption of the cured resin was confirmed. From these results, the newly prepared epoxy resin with naphthylene ether skeletons was considered to be suitable for advanced applications such as silicon carbide power semiconductor device. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43339.     

Kinetic modeling of hemicellulose hydrolysis in the presence of homogeneous and heterogeneous catalysts

Kinetic models were developed for the hydrolysis of O‐acetyl‐galactoglucomannan (GGM), a hemicellulose appearing in coniferous trees. Homogeneous and heterogeneous acid catalysts hydrolyze GGM at about 90°C to the monomeric sugars galactose, glucose, and mannose. In the presence of homogeneous catalysts, such as HCl, H₂SO₄, oxalic acid, and trifluoroacetic acid, the hydrolysis process shows a regular kinetic behavior, while a prominent autocatalytic effect was observed in the presence of heterogeneous cation‐exchange catalysts, Amberlyst 15 and Smopex 101. The kinetic models proposed were based on the reactivities of the nonhydrolyzed sugar units and the increase of the rate constant (for heterogeneous catalysts) as the reaction progresses and the degree of polymerization decreases. General kinetic models were derived and special cases of them were considered in detail, by deriving analytical solutions for product distributions. The kinetic parameters, describing the autocatalytic effect were determined by nonlinear regression analysis. The kinetic model described very well the overall kinetics, as well as the product distribution in the hydrolysis of water soluble GGM by homogeneous and heterogeneous catalysts. The modelling principles developed in the work can be in principle applied to hydrolysis of similar hemicelluloses as well as starch and cellulose. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1066–1077, 2014