TY - JOUR
AU - De La Bretèche, Régis
AU - Browning, Timothy D
ID - 221
IS - 1
JF - Michigan Mathematical Journal
TI - On Manin's conjecture for singular del Pezzo surfaces of degree four, I
VL - 55
ER -
TY - JOUR
AB - Acknowledgements. The authors are grateful to Ulrich Derenthal and Brendan Hassett for several useful conversations relating to universal torsors for singular del Pezzo surfaces. Special thanks are due to Roger Heath–Brown whose ideas led us to the proof of Lemma 6. The paper was finalised while the first author was at the École Normale Supérieure, and the second author was at Oxford University supported by EPSRC grant number GR/R93155/01. The hospitality and financial support of these institutions is gratefully acknowledged. Finally, the authors would like to thank the anonymous referee for his careful reading of the manuscript and numerous useful suggestions.
AU - de la Bretèche, Régis
AU - Timothy Browning
ID - 222
IS - 3
JF - Mathematical Proceedings of the Cambridge Philosophical Society
TI - On Manin's conjecture for singular del Pezzo surfaces of degree four, II
VL - 143
ER -
TY - JOUR
AB - Let Q be a non-singular diagonal quadratic form in at least four variables. We provide upper bounds for the number of integer solutions to the equation Q = 0, which lie in a box with sides of length 2B, as B → ∞. The estimates obtained are completely uniform in the coefficients of the form, and become sharper as they grow larger in modulus.
AU - Timothy Browning
ID - 223
IS - 1
JF - Monatshefte fur Mathematik
TI - Density of integer solutions to diagonal quadratic forms
VL - 152
ER -
TY - JOUR
AB - The main factors for reducing the consumption of a vehicle are reduction of curb weight, air drag and increase in the drivetrain efficiency. Highly efficient drivetrains can be developed based on PEFC technology and curb weight may be limited by an innovative vehicle construction. In this paper, data on consumption and efficiency of a four‐place passenger vehicle with a curb weight of 850 kg and an H2/O2 fed PEFC/Supercap hybrid electric powertrain are presented. Hydrogen consumption in the New European Driving Cycle is 0.67 kg H2/100 km, which corresponds to a gasoline equivalent consumption of 2.5 l/100 km. When including the energy needed to supply pure oxygen, the calculated consumption increases from 0.67 to 0.69–0.79 kg H2/100 km, depending on the method of oxygen production.
AU - Büchi, F. N.
AU - Paganelli, G.
AU - Dietrich, P.
AU - Laurent, D.
AU - Tsukada, A.
AU - Varenne, P.
AU - Delfino, A.
AU - Kötz, R.
AU - Freunberger, Stefan Alexander
AU - Magne, P.-A.
AU - Walser, D.
AU - Olsommer, D.
ID - 7323
IS - 4
JF - Fuel Cells
SN - 1615-6846
TI - Consumption and efficiency of a passenger car with a Hydrogen/Oxygen PEFC based hybrid electric drivetrain
VL - 7
ER -
TY - JOUR
AB - Efficiency is the key parameter for the application of fuel cells in automotive applications. The efficiency of a hydrogen/oxygen polymer electrolyte fuel cell system is analyzed and compared to hydrogen/air systems. The analysis is performed for the tank to electric power chain. Furthermore, the additional energy required for using pure oxygen as a second fuel is analyzed and included in the calculation. The results show that if hydrogen is produced from primary fossil energy carriers, such as natural gas and pure oxygen needs to be obtained by a conventional process; the fuel to electric current efficiency is comparable for hydrogen/oxygen and hydrogen/air systems. However, if hydrogen and oxygen are produced by the splitting of water, i.e., by electrolysis or by a thermochemical process, the fuel to electric current efficiency for the hydrogen/oxygen system is clearly superior.
AU - Büchi, F. N.
AU - Freunberger, Stefan Alexander
AU - Reum, M.
AU - Paganelli, G.
AU - Tsukada, A.
AU - Dietrich, P.
AU - Delfino, A.
ID - 7324
IS - 2
JF - Fuel Cells
SN - 1615-6846
TI - On the efficiency of an advanced automotive fuel cell system
VL - 7
ER -