Transceiver design for non-regenerative MIMO relay systems with decision feedback detection

In this paper we consider the design of zero forcing (ZF) and minimum mean square error (MMSE) transceivers for non-regenerative multiple input multiple output (MIMO) relay networks. Our designs utilise linear processors at each stage of the network along with a decision feedback detection device at the receiver. Under the assumption of full channel state information (CSI) across the entire link the processors are jointly optimised to minimise the system arithmetic mean square error (MSE) whilst meeting average power constraints at both the source and the relay terminals. We compare the presented methods to linear designs available in the literature and show the advantages of the proposed transceivers through simulation results

Transverse mass and invariant mass observables for measuring the mass of a semi-invisibly decaying heavy particle

Formulae are derived for the positions of end-points in the invariant mass and transverse mass distributions obtained from the products of heavy states decaying to pairs of semi-invisibly decaying lighter states. Formulae are derived both for the special case where the two decay chains are identical and the more general case where they are different. The formulae are tested with a simple case study of heavy SUSY higgs particles decaying to gauginos at the LHC.Comment: 13 pages, 8 eps figure

Attitude motion planning for a spin stabilised disk sail

While solar sails are capable of providing continuous low thrust propulsion the size and flexibility of the sail structure poses difficulties to their attitude control. Rapid slewing of the sail can cause excitation of structural modes, resulting in flexing and oscillation of the sail film and a subsequent loss of performance and decrease in controllability. Disk shaped solar sails are particularly flexible as they have no supporting structure and so these spacecraft must be spun around their major axis to stiffen the sail membrane via the centrifugal force. In addition to stiffening the structure this spin stabilisation also provides gyroscopic stiffness to disturbances, aiding the spacecraft in maintaining its desired attitude. A method is applied which generates smooth reference motions between arbitrary orientations for a spin-stabilised disk sail. The method minimises the sum square of the body rates of the spacecraft, therefore ensuring that the generated attitude slews are slow and smooth, while the spin stabilisation provides gyroscopic stiffness to disturbances. An application of Pontryagin’s maximum principle yields an optimal Hamiltonian which is completely solvable in closed form. The resulting analytical expressions are a function of several free parameters enabling parametric optimisation to be used to provide reference motions which match prescribed boundary conditions on the initial and final configurations. The generated reference motions are utilised in the repointing of a 70m radius spin-stabilised disk solar sail in a heliocentric orbit, with the aim of assessing the feasibility of the motion planning method in terms of the control torques required to track the motions

Learn While You Earn: Two Approaches to Learning Auction Parameters in Take-it-or-leave-it Auctions

Much of the research in auction theory assumes that the auctioneer knows the distribution of participants ’ valuations with complete certainty. However, this is unrealistic. Thus, we analyse cases in which the auctioneer is uncertain about the valuation distributions; specifically, we consider a repeated auction setting in which the auctioneer can learn these distributions. Using take-it-or-leave-it auctions (Sandholm and Gilpin, 2006) as an exemplar auction format, we consider two auction design criteria. Firstly, an auctioneer could maximise expected revenue each time the auction is held. Secondly, an auctioneer could maximise the information gained in earlier auctions (as measured by the Kullback-Liebler divergence between its posterior and prior) to develop good estimates of the unknowns, which are later exploited to improve the revenue earned in the long-run. Simulation results comparing the two criteria indicate that setting offers to maximise revenue does not significantly detract from learning performance, but optimising offers for information gain substantially reduces expected revenue while not producing significantly better parameter estimates

Evolution of the star formation histories of BLAST galaxies

We have measured star formation histories (SFHs) and stellar masses of galaxies detected by the Balloon-borne Large Aperture Sub-millimetre Telescope (BLAST) over approximately 9 square degrees centred on the Chandra Deep Field South. We have applied the recently developed SFH reconstruction method of Dye et al. to optical, near-infrared and mid-infrared photometry of 92 BLAST galaxies. We find significant differences between the SFHs of low mass (<10^11 M_sol) and high mass (>10^11 M_sol) galaxies. On average, low mass galaxies exhibit a dominant late burst of star formation which creates a large fraction of their stellar mass. Conversely, high mass systems tend to have a significant amount of stellar mass that formed much earlier. We also find that the high mass SFHs evolve more strongly than the low mass SFHs. These findings are consistent with the phenomenon of downsizing observed in optically selected samples of galaxies.Comment: Accepted by MNRAS Letters. 5 pages. 4 figure

A Dynamic Programming Solution to Bounded Dejittering Problems

We propose a dynamic programming solution to image dejittering problems with bounded displacements and obtain efficient algorithms for the removal of line jitter, line pixel jitter, and pixel jitter.Comment: The final publication is available at link.springer.co

Comment on "Experimental Verification of a Jarzynski-Related Information-Theoretic Equality by a Single Trapped Ion" PRL 120 010601 (2018)

The target paper presents an experimental verification of a "Jarzynski-related" equality. We show that the latter equality is in fact not related to the Jarzynski equality.Comment: 1 pag