Undular Tidal Bores: Basic Theory and Free-Surface Characteristics

The present study examines the free-surface properties of undular tidal bores observed for 1相似文献   

Design and Implementation of a PKI-Based End-to-End Secure Infrastructure for Mobile E-Commerce

The popularity of handheld mobile devices and deployment of the public key infrastructure in many parts of the world have led to the development of electronic commerce on mobile devices. For the current version of mobile phones, the main challenge is the limited computing capacity on these devices for PKI-based end-to-end secure transactions. This paper presents a new architecture and protocol for authentication and key exchange as well as the supporting infrastructure that is suitable for the mobile phone environment. The system requirements and our solutions in addressing these requirements in the restrictive environment are discussed. An evaluation of the system performance is also included. The system has been implemented and is supporting some real-life applications.     

Incubation of lipid emulsions with plasma lipoproteins modifies the fluidity of each particle

Lipid emulsions (LE) contain triglyceride (TG)-rich particles (TGRP) and phospholipid-rich particles (PLRP). Various lipid and protein exchanges take place during in vitro incubations of LE with lipoproteins. These composition changes affect physical properties of particles. The aim of this study was to determine the role of different LE particles and the effect of TG composition on physical modifications. Low density lipoproteins (LDL: 1.025<d<1.040 g/mL) or high density lipoproteins (HDL: 1.085<d<1.150 g/mL) were incubated with the following four LE or their TGRP or PLRP, which were manufactured with the same phospholipid emulsifier: long-chain triglycerides (LCT): 100% soybean oil; medium-chain triglycerides (MCT)/LCT (MCT/LCT, 5∶5, w/w); FO (100% fish oil); and MLF541 (MCT/LCT/FO, 5∶4∶1, by wt). After incubation, modified LE particles and lipoproteins were analyzed by fluorescence polarization. Observed physical modifications were significant in emulsion particles (ordering effect) but not in lipoporteins and also were significant for TG composition effect. Since intact emulsion contained a large excess of TGRP over PLRP, it is not surprising that intact emulsion had the same behavior as TGRP alone, and that PLRP had the same physical characteristics as lipoproteins. TG loss and cholesterol and protein acquisitions by emulsion particles rigidify their envelope. The two emulsions containing FO were less ordered after incubation. In conclusion, incubation of LE with lipoproteins changes physical properties of each kind of particle, and TG composition of the emulsion affects emulsion particle changes but has no effect on LDL and HDL. These order modifications induce more effective exchanges between LE particles and lipoproteins and modify their metabolism; HDL changes may increase the reverse cholesterol transport.     

Logical inference of clauses based on Petri net models

This paper extends the logical inference of Horn clauses in Petri net models to cover a large class of non-Horn clauses. Based on four-valued logic and the conflict transition concept, we show how the Petri net model for this class of non-Horn clauses can be constructed. The clause inference is solved by the T-invariant method or the fixpoint of markings. Both forward and backward inference can be used in our model. It is further shown that these techniques are efficient for the common classes of monotonic reasoning. © 1998 John Wiley & Sons, Inc.     

Hydraulic Performances of Minimum Energy Loss Culverts in Australia

Culverts are among the most common hydraulic structures. Modern designs do not differ from ancient structures and are often characterized by significant afflux at the design flows. A significant advance was the development of the minimum energy loss (MEL) culverts in the late 1950s. The design technique allows a drastic reduction in the upstream flooding associated with lower costs. The development and operational performances of this type of structure is presented. The successful operation of MEL culverts for more than 40 years is documented with first-hand records during and after floods. The experiences demonstrate the design soundness, while highlighting the importance of the hydraulic expertise of the design engineers.     

Process groups and group communications: classifications andrequirements

Different distributed applications are examined and their requirements for group communication support are outlined. The concept of a process group is defined. On the basis of internal structures and external behavior, groups are classified into different categories and their properties are discussed. Group communication is an OS-level abstraction that offers convenience and clarity to the programmer