31 research outputs found
COMBUSTION AND EMISSIONS FORMATION IN DIESEL ENGINE FUELED BY POLYOXYMETHYLENE DIMETHYL ETHER AND ITS BLENDS
No full textPh.DDOCTOR OF PHILOSOPHY (FOE
Auto-ignition of polyoxymethylene dimethyl ether 3 (PODE3) blended with diesel and gasoline via combustion under homogeneous charge compression ignition
No full textWith high oxygen content and cetane number, PODE3 is a favorable renewable fuel for engines. PODE3/diesel/gasoline blends in a HCCI engine are numerically studied for the first time. The effects of fuel blend ratio and equivalence ratio (ER) on auto-ignition are investigated. A highly compact and robust chemical mechanism has been implemented. Crank angle at which 50 percent of heat is released (CA50) displays higher sensitivity towards blend ratio in leaner mixtures with 50% PODE3 displaying a change of 12.31 CAD at 0.34 ER and only 6.19 CAD at 0.5 ER when made in comparison to their respective CA50 at 100% PODE3. Furthermore, indicated thermal efficiency (ITE) is observed to be better with higher ER with 100% PODE3 having a 23.3% increase in ITE at 0.5 ER than at 0.34 ER, and is generally higher with increased PODE3. Neat PODE3 displays lowest CO and highest CO2 for all cases, manifesting high oxidation reactivity. Additionally, acetylene levels are substantially lower for combustions at 0.5 ER as compared to 0.34 ER. Lastly, PODE3 yields only 2.04 × 10−10g/cycle and 5.67 × 10−11g/cycle of C2H2 at 0.34 ER and 0.5 ER respectively. With nearly no soot precursors, PODE3 demonstrates high potential in encouraging clean combustion
Development of a compact and robust Polyoxymethylene Dimethyl Ether 3 reaction mechanism for internal combustion engines
No full text10.1016/j.enconman.2019.02.007ENERGY CONVERSION AND MANAGEMENT18535-4
A novel non-Gaussian embedding based model for recommender systems
No full textInternational audienceTraditional recommender systems employ a history of item preferences by a set of users for recommending items of interest to a given user. Matrix factorization based models have achieved the state-of-the-art success in the personal recommendation tasks by aiming at predicting ratings through learning latent factors of users and items via the rating matrix decomposition. Matrix factorization based models treat ratings as integers which are supposed to be generated from Gaussian distribution assumption all the time, but long-tail distribution widely exists in real rating data. Moreover, these approaches always ignore the semantic meanings of ratings which can expose the underlying attitudes of users with respect to many aspects of items. In this paper we propose a novel non-Gaussian embedding based model for recommender systems (NGEM) that represents each rating as a translation between users and items in the rating-dependent subspace. Then various types of initializations are incorporated into the proposed model to enhance the learned embeddings of users, items and ratings for better optimization. The effectiveness of our proposed model is demonstrated on rating-prediction task by extensive experiments on the real-world data sets. The results also show that different types of initializations help our model achieve an improvement on accuracy in comparison with some state-of-the-art matrix factorization based models
Putting precision and elegance in enzyme immobilisation with bio-orthogonal chemistry
No full textThe covalent immobilisation of enzymes generally involves the use of highly reactive crosslinkers, such as glutaraldehyde, to couple enzyme molecules to each other or to carriers through, for example, the free amino groups of lysine residues, on the enzyme surface. Unfortunately, such methods suffer from a lack of precision. Random formation of covalent linkages with reactive functional groups in the enzyme leads to disruption of the three dimensional structure and accompanying activity losses. This review focuses on recent advances in the use of bio-orthogonal chemistry in conjunction with rec-DNA to affect highly precise immobilisation of enzymes. In this way, cost-effective combination of production, purification and immobilisation of an enzyme is achieved, in a single unit operation with a high degree of precision. Various bio-orthogonal techniques for putting this precision and elegance into enzyme immobilisation are elaborated. These include, for example, fusing (grafting) peptide or protein tags to the target enzyme that enable its immobilisation in cell lysate or incorporating non-standard amino acids that enable the application of bio-orthogonal chemistry.BT/Biocatalysi
Development of a Highly Compact and Robust Chemical Reaction Mechanism for Unsaturated Furan Oxidation in Internal Combustion Engines via a Multiobjective Genetic Algorithm and Generalized Polynomial Chaos
No full text10.1021/acs.energyfuels.9b03272ENERGY & FUELS341936-94
Optimization of a Coil System for Generating Uniform Magnetic Fields inside a Cubic Magnetic Shield
No full textUltra-low magnetic fields have drawn lots of attention due to their important role in scientific and technological research. The combination of a magnetic shield and an active compensation coil is adopted in most high performance magnetically shielded rooms. Special consideration needs to be taken in the coil design since the magnetic shield significantly affects the uniformity of the magnetic field that is generated by the coil. An analytical model for the magnetic field calculation of the coil inside a cubic magnetic shield is proposed based on the generalized image method, which is validated by finite element analysis. A novel design method of the coil used in a cubic magnetic shield with a large homogeneous volume is proposed. The coil parameters are optimized to obtain a large cubic uniform volume with desired total deviation rate by discretizing the central volume in the coil. In the desired total deviation rate, the normalized usable volume of the new coil increases by 70% when compared with the Merritt coil. A coil system is developed according to the parameters obtained based on this method. The magnetic flux density and practical deviation rate of the coil are measured to validate the accuracy of this model and the feasibility of the design method. The experimental magnetic flux density agrees well with the analytical value. The maximum practical deviation rate of uniform volume of 0.8 × 0.8 × 0.8 m is in good agreement with the theoretical design value, taking into account the experiment errors
