Reducing handover latency and improving tcp performance in wireless networks

Chemical processes at the interfaces often differ kinetically and mechanistically from the bulk counterparts, partly due to the concentration inhomogeneity of different chemicals at the interfaces. The fractionation of chemicals at the interfaces not only determines their interfacial concentrations, but also affects the physicochemical properties of the interfaces. In this thesis, three sets of chemicals/interfaces with important environmental implications are studied: (1) anion fractionation at the gas–liquid microdroplet interfaces, (2) fractionation of perfluoroalkyl surfactants and matrix components at the bubble–water interface in ultrasonically irradiated solutions, and (3) ion fractionation across the ice–water interface during the freeze–thaw cycle of electrolyte solutions. The relative anion affinity for the air–water interface, as measured by Electrospray Mass Spectrometry (ES–MS), is exponentially correlated with ionic radius. The affinities respond differently to different additives, suggesting that specific anion effects are due to different energy levels of physical interactions. Relative anion affinities at the air–methanol interfaces are almost identical to those at the air–water interface, suggesting that surface structure is not the primary driving force for interfacial anion fractionation. Perfluoroalkyl carboxylates and sulfonates can be transferred from the ocean to marine aerosols due to their high affinity for the air–water interface, but transfer to gas phase is unlikely as they remain deprotonated in aqueous phase because of their low pKa. Organic matrix components may reduce the sonochemical kinetics of Perfluorooctanesulfonate (PFOS) and Perfluorooctanoate (PFOA) by competitive adsorption onto the bubble–water interface or by lowering the interfacial temperatures. Inorganic anions, but not cations, may significantly enhance or reduce the sonochemical kinetics of PFOS and PFOA. The specific anion effects following the Hofmeister series are likely related to anions’ partitioning to and interaction with the bubble–water interface. Time–resolved confocal fluorescence microscopy of freezing electrolyte solutions reveals that the thickness of interstitial liquid films depends non–monotonically on electrolyte concentration. It also confirms that selective incorporation of cations (anions) into the ice lattice decreases (increases) the pH of the interstitial liquid films. Since the magnitude of pH change during freezing is smaller than during the subsequent thawing process, it is likely to be limited by the seepage of proton or hydroxide slowly produced via water dissociation.

An overview of electrified interfaces structure and electronic properties of metal surfaces physics of surfaces ab-inito molecular dynamics - selected applications to disordered systems and surfaces the problem of Schottky barrier the semiconductor/electrolyte interface stark effect on adsorbates at electrified interfaces thermodynamics of adsorption electrode potentials and energy scales phenomenological approach to metal/electrolyte interfaces the application of scanning tunnelling microscopy to electrochemistry singly crystal electrodes modelling of metal-water electrified interfaces molecular models of organic adsorption from water at charged interfaces the interface between a metal and a solution in the absence of specific adsorption adsorption at the metal/solution interface electron-transfer reactions at metal-solution interfaces - an introduction to some contemporary issues the solid-electrolyte interface as exemplified by hydrous oxides - surface chemistry and surface reactivity discrete charges on biological membranes structural rearrangements in lipid bilayer membranes evaluation of the surface potential at the membrane-solution interface of photosynthetic bacterial systems electrical currents of the light driven pump bacteriorhodopsin the role of asp 85 and asp 96 on proton translocation the electrochemical relaxation at thylakoid membranes evaluation of the electric field in a protein by dynamic measurements of proton transfer.

Vitreo-retinal surgery encompasses the surgical procedures performed on the vitreous humor and the retina. A procedure typically consists of the removal of the vitreous humor, the peeling of a membrane and/or the repair of a retinal detachment. Operations are performed with needle shaped instruments which enter the eye through surgeon made scleral openings. An instrument is moved by hand in four degrees of freedom (three rotations and one translation) through this opening. Two rotations (? and ? ) are for a lateral instrument tip movement. The other two DoFs (z and ?) are the translation and rotation along the instrument axis. Actuation of for example a forceps can be considered as a fifth DoF. Characteristically, the manipulation of delicate, micrometer range thick intraocular tissue is required. Today, eye surgery is performed with a maximum of two instruments simultaneously. The surgeon relies on visual feedback only, since instrument forces are below the human detection limit. A microscope provides the visual feedback. It forces the surgeon to work in a static and non ergonomic body posture. Although the surgeon’s proficiency improves throughout his career, hand tremor may become a problem around his mid-fifties. Robotically assisted surgery with a master-slave system enhances dexterity. The slave with instrument manipulators is placed over the eye. The surgeon controls the instrument manipulators via haptic interfaces at the master. The master and slave are connected by electronic hardware and control software. Implementation of tremor filtering in the control software and downscaling of the hand motion allow prolongation of the surgeon’s career. Furthermore, it becomes possible to do tasks like intraocular cannulation which can not be done by manually performed surgery. This thesis focusses on the master console. Eye surgery procedures are observed in the operating room of different hospitals to gain insight in the requirements for the master. The master console as designed has an adjustable frame, a 3D display and two haptic interfaces with a coarse adjustment arm each. The console is mounted at the head of the operating table and is combined with the slave. It is compact, easy to place and allows the surgeon to have a direct view on and a physical contact with the patient. Furthermore, it fits in today’s manual surgery arrangement. Each haptic interface has the same five degrees of freedom as the instrument inside the eye. Through these interfaces, the surgeon can feel the augmented instrument forces. Downscaling of the hand motion results in a more accurate instrument movement compared to manually performed surgery. Together with the visual feedback, it is like the surgeon grasps the instrument near the tip inside the eye. The similarity between hand motion and motion of the instrument tip as seen on the display results in an intuitive manipulation. Pre-adjustment of the interface is done via the coarse adjustment arm. Mode switching enables to control three or more instruments manipulators with only two interfaces. Two one degree of freedom master-slave systems with force feedback are built to derive the requirements for the haptic interface. Hardware in the loop testing provides valuable insights and shows the possibility of force feedback without the use of force sensors. Two five DoF haptic interfaces are realized for bimanual operation. Each DoF has a position encoder and a force feedback motor. A correct representation of the upscaled instrument forces is only possible if the disturbance forces are low. Actuators are therefore mounted to the fixed world or in the neighborhood of the pivoting point for a low contribution to the inertia. The use of direct drive for ' and and low geared, backdriveable transmissions for the other three DoFs gives a minimum of friction. Disturbance forces are further minimized by a proper cable layout and actuator-amplifier combinations without torque ripple. The similarity in DoFs between vitreo-retinal eye surgery and minimally invasive surgery (MIS) enables the system to be used for MIS as well. Experiments in combination with a slave robot for laparoscopic and thoracoscopic surgery show that an instrument can be manipulated in a comfortable and intuitive way. User experience of surgeons and others is utilized to improve the haptic interface further. A parallel instead of a serial actuation concept for the ' and DoFs reduces the inertia, eliminates the flexible cable connection between frame and motor and allows that the heat of the motor is transferred directly to the frame. A newly designed z-?? module combines the actuation and suspension of the hand held part of the interface and has a three times larger z range than in the first design of the haptic interface.

High-order adaptive mesh refinement offers the potential for accurate and efficient resolution of problems in fluid dynamics and other fields where a wide range of length scales is present. A critical requirement for the interface closures used with these methods is stability in the context of hyperbolic systems of partial differential equations. In this study, a class of energy-stable high-order finite-difference interface closures is presented for grids with step resolution changes in one dimension. Asymptotic stability in time for these schemes is achieved by imposing a summation-by-parts condition on the interface closure, which is thus also nondissipative. Interface closures compatible with interior fourth- and sixth-order explicit, and fourth-order implicit centered schemes are presented. Validation tests include linear and nonlinear problems in one and in two dimensions with tensor-product grid refinement. A second class of stable high-order interface closures is presented for two-dimensional cell-centered grids with patch-refinement and step-changes in resolution. For these grids, coarse and fine nodes are not aligned at the mesh interfaces, resulting in hanging nodes. Stability is achieved by again imposing a summation-by-parts condition, resulting in nondissipative closures, at the cost of accuracy at corner interfaces. Interface stencils for an explicit fourth-order finite-difference scheme are presented for each geometry. Validation tests confirm the stability and accuracy of these closures for linear and nonlinear problems. The Richtmyer-Meshkov instability is investigated using a novel first-order perturbation of the two-dimensional Navier-Stokes equations about a shock-resolved base flow. The computational domain is efficiently resolved using the one-dimensional fourth-order interface scheme. Results are compared to analytic models of the instability, showing agreement with predicted asymptotic growth rates in the inviscid range, while significant discrepancies are noted in the transient growth phase. Viscous effects are found to be poorly predicted by existing models.

The structure of charged interfaces

This paper describes two approaches to the automatic generation of behavioral VHDL models from descriptions written in natural language. Both approaches are based on a modeling style in which behavior is represented by a system of interconnected processes. The first approach employs a semantic grammar to directly generate a single VHDL process from a paragraph written in a restricted English called ModelSpeak. The second approach accepts more general English and generates models consisting of multiple processes. series of sentences describing the behavior of a single process and generated correct VHDL code for it. This interface requires the behavior be expressed in a highly restricted English called ModelSpeak (10). Conditional expressions (if statements) may be nested to two levels, and interaction is invoked by the interface to resolve scope ambiguity of loops. This interface is implemented with a semantic grammar (3) in Prolog. The second interface (Approach II) to the Modeler's Assistant for natural language is substantially more complex, but accepts more general English expressions and generates multiple-process models. In this approach, each sentence is parsed by a bottom-up, parallel chart parser to generate a set of valid parse trees. The trees are examined by a Semantic Analyzer (7) to determine one which is semantically correct, and a conceptual graph (14) (semantic network) of its meaning is generated. Once the conceptual graph of individual sentences are joined together (12), a program called the Linker (8) analyzes the graph to produce a Process Model Graph and VHDL process code for the Modeler's Assistant. Nodes in the conceptual graph representing verbs typically generate processes or the conditions which govern them. Nodes representing objects generate signals. The modeling style underlying the Linker produces a sizable collection of processes, each consisting of a single if_then statement. To avoid unnecessary bus resolutions, multiple processes assigning to the same signal are merged. Since signal types are generally not expressed in the English description, they may be added interactively later. Before describing the approaches in more detail, related research on natural language interfaces is reviewed briefly.

In this thesis, we use integral equation methods to study the scattering of timeharmonic electromagnetic plane waves by biperiodic multilayered structures. Here, such structures are modeled by vertically arranging finitely many non-self-intersecting polyhedral Lipschitz interfaces. We distinguish single profile scatterers and scatterers composed of at least two surfaces. The electromagnetic scattering problem, which arises from the presence of obstacles of the first type, serves as a basic model that we reuse in the multilayered case. By treating it with a combined potential ansatz, we obtain an equivalent new periodic singular integral equation with Fredholm index zero. The Fredholmness is verified by Garding inequalities. This property is crucial for proving one of the main results of our analysis in the single interface setting: an existence theorem for the derived integral equation under certain assumptions on the electromagnetic material parameters. The second central result, a uniqueness theorem, is proven by a variational argumentation and again depends on the values of the electromagnetic material parameters. In the main part of this thesis, we then extend the considered obstacles to “real” multilayered obstacles consisting of at least two grating interfaces. For these, we propose two recursive integral equation algorithms to determine the generated reflected and transmitted waves. On the one hand, the recursive scattering matrix method and, on the other hand, a recursive algorithm based on the transmission conditions across the interfaces of the multilayered structure. In addition to their accurate derivation, new existence and uniqueness results, depending on the electromagnetic properties of the considered obstacle, are presented for each algorithm. Their proofs partially exploit the insights originating from the treatment of the single interface model problem. Our analytical investigation is intended to provide a basis for new efficient numerical implementations of the biperiodic multilayered electromagnetic scattering problem.

TCP performance in contention-based multi-hop wireless networks is shaped by two main factors, which are unlike the wired network case. First, the maximum throughput for a given topology and flow pattern is reached at an optimal congestion window. We provide an improved analysis of this effect. Second, the control traffic uses higher proportion of the channel bandwidth than in the wired case. Our results show that the much smaller TCP ACKpackets consume channel resource comparable to the much longer data packets, over high-speed connections. Motivated by this understanding, we reformulate and enhance an existing idea for improving TCP performance by further lowering the number of control packets. Extensive simulations show that our strategy increases the TCP throughput up to 205% compared to the regular TCP, in long-hop wireless networks and 35% in a complex network.

Examples, Ion Properties and Concepts: The Past and What Can Be Learnt from It (W Kunz et al.) Specific Ion Properties (G Hefter) Ion-Surfactant Interactions: Experiments and Models (E Leonitis) Promising Experimental Techniques: Probing Specific Ion Effects with Grazing Incidence X-Ray Diffraction (J Daillant) Neutron Scattering, Simulation, Denaturants (P E Mason & G Neilson) Specific Ion Effects at The Air-Water Interface - New Experimental Studies (V Craig) Newest Results From Theory and Simulation: Simulations of Ions at the Air-Water Interface and Near Biomolecules (M Lund & P Jungwirth) Simulations of Ion Near Water-Solid Interfaces and in Bulk Water (R Netz & D Horinek) HNC Calculations of Specific Ion Effects (L Belloni) and other papers.

As smart homes become more widespread, the need for more natural forms of interaction in the home also increases. On the one hand, forcing a user to go to a central home controller at every required change does not make sense. On the other hand, having a different controller for each device is also quite overwhelming. Object-Specific Interfaces (OSIs) allow an interface customized to an object of interest to show up on a mobile device when in close proximity to it. The interface can be passive, thus showing a manual or information, or interactive and so would allow for device monitoring and controlling.

Single molecule detection and fluorescence correlation spectroscopy on surfaces

Augmented tabletops have recently attracted considerable attention in the literature. However, little has been known about the effects that these interfaces have on learning tasks. In this paper, we report on the results of an empirical study that explores the usage of tabletop systems in an expressive collaborative learning task. In particular, we focus on measuring the difference in learning outcomes at individual and group levels between students using two interfaces: traditional computer and augmented tabletop with tangible input.No significant effects of the interface on individual learning gain were found. However, groups using traditional computer learned significantly more from their partners than those using tabletop interface. Further analysis showed an interaction effect of the condition and the group heterogeneity on learning outcomes. We also present our qualitative findings in terms of how group interactions and strategy differ in the two conditions.

The re is a growing need for robot control interfaces that allow a single user to effe ctively control a large number of mostly-autonomous robots. The ch allenges in controlling such a collection of robots are very similar to the challenges of controlling characters in some genres of video games. In this paper, we argue that interfaces based on elements from computer video games are effe ctive tools for the control of large robot teams. We present RIDE, the Robot Interactive Display Environment, an example of such an interface, and give the results of initial user studies with the interface, which lend support to our claim. Follow this and additional works at: htt p://openscholarship.wustl.edu/cse_research Part of the Computer Engineering Commons, and the Computer Sciences Commons

Local area network and wide area network are different network protocols, small and medium enterprises due to the geographical distribution of discrete and interface diversity, leading to its needs to be compatible with different network protocols, it is difficult to use a single network protocol to realize network architecture, and due to the ipv4 address scarcity, making its application or maintenance cost greatly increased, based on this, this paper presents the design of multi-protocol network architecture based on point-to-point protocol and frame relay, and with the advantages of the router is compatible with a variety of interfaces and protocols to connect different network interfaces, the paper also gives the configuration of routing information protocol and static routing through local area network, the paper presents the core information of frame relay and point-to-point protocol among the routers, and the paper gives the realization of the network address translation in the end.

The level set method is a mathematical and computational, technique for tracking a moving interface over time. It can naturally handle topological changes such as merging or breaking interfaces. Intrinsic geometric properties of the interface, such as curvature and normal direction, are easily determined from the level set function p. There are many applications of the level set method, including kinetic crystal growth, epitaxial growth of thin films, image restoration, vortex dominated flows, and so forth. Most applications described in the growing literature on the applications of level sets advance the level set equation with explicit time integration. Hence, small CFL-respecting time steps are needed to maintain stability. In this thesis, an implicit level set method is introduced and applied to wildland firespread models, removing vulnerability to instability.