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.

Series solution methods have recently been used to solve fully nonlinear flow over topography problems. These methods are iterative schemes that update an initial estimate of the fluid surface (a free boundary) using a cost function. Series solutions are obtained efficiently and accurately with exact error bounds immediately available. Critical to the speed of the procedure is the implementation of efficient computer code and numerical techniques. In this paper we discuss methods that improve the computational time of the original implementation by several orders of magnitude, without any loss of accuracy. The efficiency of the improved method is demonstrated by generating two dimensional solutions to subcritical flow over an isolated cosine shaped obstacle.

/pdf/optimising-series-solution-methods-for-flow-over-topography-305al8l79i.pdf

Optimising series solution methods for flow over topography---Part 1

Shill bidding occurs when fake bids are introduced into an auction on the seller's behalf in order to artificially inflate the final price. This is typically achieved by the seller having friends bid in her auctions, or the seller controls multiple fake bidder accounts that are used for the sole purpose of shill bidding. We previously proposed a reputation system referred to as the Shill Score that indicates how likely a bidder is to be engaging in price inflating behaviour with regard to a specific seller's auctions. A potential bidder can observe the other bidders' Shill Scores, and if they are high, the bidder can elect not to participate as there is some evidence that shill bidding occurs in the seller's auctions. However, if a seller is in collusion with other sellers, or controls multiple seller accounts, she can spread the risk between the various sellers and can reduce suspicion on the shill bidder. Collusive seller behaviour impacts one of the characteristics of shill bidding the Shill Score is examining, therefore collusive behaviour can reduce a bidder's Shill Score. This paper extends the Shill Score to detect shill bidding where multiple sellers are working in collusion with each other. We propose an algorithm that provides evidence of whether groups of sellers are colluding. Based on how tight the association is between the sellers and the level of apparent shill bidding is occurring in the auctions, each participating bidder's Shill Score is adjusted appropriately to remove any advantages from seller collusion. Performance has been tested using simulated auction data and experimental results are presented.

Detecting Multiple Seller Collusive Shill Bidding

This paper describes a security problem involving an online data repository, which acts as a proxy for multiple companies allowing their customers to perform online services (e.g., pay invoices). The repository's host is trusted to honestly fulfil its duties in maintaining the data in a manner consistent with each companies' required services. However, the information stored by the repository remains private in that the repository's host cannot openly read any companies' operational data, nor does it learn the identities of any companies' customers. We contrast several approaches describing their viability for web deployment using existing technologies. This is a fundamentally new security problem with no established literature or clearly defined cryptographic solution. The project originated from a commercial attempt to design a secure online data archive. A sample implementation of the system is presented that allows a customer to pay and view invoices online via the data repository using a popular and widely available small business accountancy application.

Privacy and anonymity in untrusted data stores

Buying and selling online is inherently insecure
Misuse of an individual's personal information is now the leading concern among those who engage in e-commerce This book examines privacy and security issues in online auctions Various auction fraud issues are investigated, and several novel counter measures proposed An online auction server was constructed to aid in developing these security measures This allowed investigation and testing in a controlled environment The research results include:

1) A complete model for conducting secure and anonymous online auctions;

2) A complete model for conducting secure and anonymous online share trading;

3) Autonomous bidding agents which bid maliciously;

4) A method for detecting a fraudulent bidding practice referred to as shill bidding; and

5) Several alternate proposals for auction clearing algorithms

The proposed security mechanisms have been implemented on the online auction server Results are given as simulated and practical tests In addition, the auction server's software design is documented
Many of the techniques discussed in this research can be readily applied to commercial online auctions

Shilled: Fraud and Security in Online Auctions

In this paper, a two-dimensional analytic series solution for groundwater flow with a free water table condition is derived and demonstrated on a two-layer unconfined aquifer with complex (ie, natural) stratigraphy The vertical side and bottom boundaries of the model domain are impermeable, and the water table is a free-boundary condition governed by both Dirichlet and Neumann conditions Unlike previous investigations, the problem is complicated by the possible intersection of the water table with interfaces between different materials This challenge can be overcome by intelligently revising the analytic series solution approach previously developed by the authors The series coefficients are calculated through a least-squares method which minimizes errors Tests cases are used to demonstrate the effects of both system geometry and lower aquifer conductivity upon the shape of the water table surface

https://congress.cimne.com/cmwr2010/Proceedings/docs/p197.pdf

Wayne Read

Papers

Optimising series solution methods for flow over topography---Part 1

Detecting Multiple Seller Collusive Shill Bidding

Privacy and anonymity in untrusted data stores

Shilled: Fraud and Security in Online Auctions

An iterative series solution approach for solving the free-boundary condition in groundwater flow systems