Fractional Differential Equations

Object-oriented analysis

Harmonic Analysis and the Theory of Probability. By S. Bochner pp. 176. 35s. 1955. (California University Press and Cambridge University Press)

Advective flows rapidly transport water, solutes, and particles into and out of permeable sand beds and significantly affects the biogeochemistry of coastal environments. In this paper, we reviewed the drivers of porewater and groundwater advection in permeable shelf sediments in an attempt to bridge gaps among different disciplines studying similar problems. We identified the following driving forces: (1) terrestrial hydraulic gradients, (2) seasonal changes in the aquifer level on land moving the location of the subterranean estuary, (3) wave setup and tidal pumping, (4) water level differences across permeable barriers, (5) flow- and topography-induced pressure gradients, (6) wave pumping; (7) ripple and other bed form migration, (8) fluid shear, (9) density-driven convection, (10) bioirrigation and bioturbation, (11) gas bubble upwelling, and (12) sediment compaction. While these drivers occur over spatial scales ranging from mm to km, and temporal scales ranging from seconds to years, their ultimate biogeochemical implications are very similar (i.e., they are often a source of new or recycled nutrients to seawater and transform organic carbon into inorganic carbon). Drivers 2–12 result in no net water input into the ocean. Taking all these mechanisms into account, we conservatively estimate that a volume equivalent to that of the entire ocean is filtered by permeable sediments at time scales of about 3000 years. Quantifying the relative contribution of these drivers is essential to understand the contribution of sediments to the global cycles of matter.

The driving forces of porewater and groundwater flow in permeable coastal sediments: a review

Glutamine utilization by the small intestine.

Bid sniping is a dubious practice used in online auctions whereby a bidder makes a bid in the closing moments in an attempt to deny other bidders time to react. The primary goal for a bid sniper is to win the auction for the lowest price possible, without the risk of being forced into submitting any higher bids if there is competition for the item. This paper investigates the phenomenon of bid sniping and its prevalence in commercial online auctions. We seek to show the extent of bid sniping, understand the rationale of why it occurs, what effect this has on the other auction participants, and what can be done to prevent the practice. Based on this understanding, we present a software bidding agent that follows a bid sniping strategy. The agent has the ability to suppress an auction's price through knowing when to bid, how much to bid, how to deal with rivals, and when to cease bidding. We also propose a new online auction format that can eliminate/reduce the effect of bid sniping. The proposal adds an undisclosed random time-out extension to an auction's finishing time to entice bidders to bid their maximum amount immediately or risk being excluded from the auction.

Targeting the Strategies of a Bid Sniper

A comparison of analytic series methods for Laplacian free boundary problems

Fluid flowing over topography occurs in many physical situations. As a consequence, study of flow over topography has been a research topic of prime interest for many decades. Formally, the problem can be modelled as a nonlinear free boundary problem. Although methods such as boundary integrals are typically used, analytic series methods have also been developed to solve some of these problems. Arguably the hardest problem to solve is the lee wave problem: when the flow conditions are suitable, waves form downstream of the obstacle. Wave solutions pose several problems for the analytic series methods. The solution method is iterative, and at each step the existing solution must be updated. For the iterative scheme to converge, very accurate series solutions must be obtained at each step. The convergence rate of the series solution itself is critical in this process, and depends to a large extent on the free boundary representation. In this paper, we compare and discuss the convergence rates for a variety of free surface representations. We show that spectral convergence is possible if the correct representation is used.

/pdf/efficient-series-solutions-for-non-linear-flow-over-2fdy3cbznr.pdf

Efficient series solutions for non-linear flow over topography

Nonuniform, initial, excess pore-water pressure distributions in the horizontal direction will have a different impact on the consolidation behavior of the soil layer, when compared with the uniform pore-water pressure distributions discussed in the literature. In the current study, various practical instances in which the nonuniform, axisymmetric, horizontal distributions of pore-water pressure occur are identified. The influence of these distribution patterns on the consolidation response of a cylindrical soil layer draining only at its peripheral face is analyzed analytically using a simple series solution method and by finite-element analysis using PLAXIS. From the Uavg-T curves and pore-water pressure isochrones developed, it is observed that the uniform pore-water pressure assumption overestimates the degree of consolidation achieved for various pore-water pressure distribution conditions and important information about pore-water pressure redistribution is overlooked. Incorporating appropriate initial pore-water pressure distribution will enable realistic estimates of the degree of consolidation to be made.

Consolidation Behavior of a Cylindrical Soil Layer Subjected to Nonuniform Pore-Water Pressure Distribution

Security and privacy in online auctions is a major concern as auction participants have many opportunities to cheat (e.g., repudiate bids, not deliver items, etc.). Online auctions such as those used by eBay are based on a type of auction referred to as an English auction. Dispite the English auction being the most popular type of auction, it has received less security coverage than other types of auctions (e.g., sealed-bid auctions). An existing proposal for a “secure” English auction prevents the Auctioneer from closing the auction early and from blocking bids, but does not protect a bidder’s anonymity. Another proposal provides anonymity, but does not stop an Auctioneer from skewing its clock or blocking bids. This paper proposes a new scheme for conducting secure and anonymous online English auctions using a modified type of group signature. Trust is divided among three servers owned by separate companies to ensure anonymity and fairness. Our scheme solves the problems of the existing English auction schemes and has following characteristics: unforgeability, anonymity, unlinkability, exculpability, coalition-resistance, verifiability, robustness, traceability, revocation, one-off registration, unskewability and unblockability. Our scheme has comparable efficiency to the existing schemes for the enhanced security and privacy it provides.

Wayne Read

Papers

Targeting the Strategies of a Bid Sniper

A comparison of analytic series methods for Laplacian free boundary problems

Efficient series solutions for non-linear flow over topography

Consolidation Behavior of a Cylindrical Soil Layer Subjected to Nonuniform Pore-Water Pressure Distribution

Secure Online English Auctions