Rapports de stage
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Rapports de stage
In this chapter we study the properties of a plasma in an electric field Our treatment of magnetized plasmas will await consideration of individual charged particle orbits in spatially and time varying electric and magnetic fields presented in Chapter Thus in this chapter the Lorentz force is simple F qE We look at basic phenomena such as plasma breakdown equilibrium di usion and plasma wall interactions including sheath physics and Langmuir probes To commence let us look at plasma equilibrium in the presence of an E field
22 pages
English
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Rapports de stage
Symmetries and symmetry breakings: the fabric of physical interactions and the flow of time1 Giuseppe Longo Dépt d'Informatique CNRS Ecole Normale Supérieure et CREA Polytechnique Paris http: www di ens fr users longo Summary This short note develops some ideas along the lines of the stimulating paper by Heylighen Found Sci 2010a It summarizes a theme in several writings with Francis Bailly downloadable from this author's web page The “geometrization” of time and causality is the common ground of the analysis hinted here and in Heylighen's paper Heylighen adds a logical notion consistency in order to understand a possible origin of the selective process that may have originated this organization of natural phenomena We will join our perspectives by hinting to some gnoseological complexes common to mathematics and physics which may shed light on the issues raised by Heylighen Note: Francis Bailly passed away recently: his immense experience in physics has been leading our joint work for many years Historically it is with relativist physics that there occurs a “change of perspective”: we pass from “causal laws” to the structural organization of space and time or even from causal laws to the “legality normativity of geometric structures” This understanding of causal laws by the identification of structural organizations stems essentially from the intrinsic duality existing between the characterization of the geometry of the universe and that of energy momentum within that universe By this duality and the putting into effect of the principle of invariance under the differentiable transformations of space time the “forces” are relativized to the nature of this geometry: they will even appear or disappear according to the geometric nature of the universe chosen a priori to describe physical behaviors Now it is similar for quantum physics in gauge theories Here gauge groups operate upon internal variables such as in the case of relativity where the choice of local gauges and their changes enable to define or ...
3 pages
English
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Rapports de stage
General Description The MAX3222E MAX3232E MAX3237E MAX3241E are 3V powered EIA TIA and V V communications interfaces with low power requirements high data rate capabilities and enhanced electrostatic discharge ESD protection All transmitter outputs and receiver inputs are protected to ±15kV using IEC Air Gap Discharge ±8kV using IEC Contact Dis charge and ±15kV using the Human Body Model The MAX3237E's logic and receiver I O pins are protected to the above standards while the transmitter output pins are protected to ±15kV using the Human Body Model The transceivers have a proprietary low dropout transmit ter output stage delivering true RS performance from a 0V to 5V supply with a dual charge pump The charge pump requires only four small F capacitors for operation from a 3V supply Each device is guaran teed to run at data rates of 250kbps while maintaining RS output levels The MAX3237E is guaranteed to run at data rates of 250kbps in the normal operating mode and 1Mbps in the MegaBaud™ operating mode while main taining RS compliant output levels The MAX3222E MAX3232E have two receivers and two drivers The MAX3222E features a A shutdown mode that reduces power consumption and extends battery life in portable systems Its receivers can remain active in shutdown mode allowing external devices such as modems to be monitored using only A supply current Both the MAX3222E and MAX3232E are pin package and functionally compatible with the industry standard MAX242 and MAX232 respectively The MAX3241E is a complete serial port three drivers five receivers designed for notebook and subnotebook com puters The MAX3237E five drivers three receivers is ideal for peripheral applications that require fast data transfer Both devices feature a shutdown mode in which all receivers can remain active while using a supply cur rent of only A MAX3241E or 10nA MAX3237E The MAX3237E MAX3241E have additional receiver outputs that always remain active The MAX3222E and MAX3232E are available in space saving SO SSOP and TSSOP packages The ...
20 pages
English
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Rapports de stage
IP Smart Object networks also referred to as LLN Low power and Lossy Networks have unique characteristics and requirements Indeed by contrast with “typical” IP networks where powerful routers are interconnected by highly stable links LLNs are usually interconnected by low power low bandwidth links offering between a few Kbits s and a few hundreds of Kbits s In addition to providing limited bandwidth such links especially wireless are usually extremely unstable with high BER Bit Error Rate It is not unusual to see the PDR Packet Delivery Rate oscillating between and with large bursts of unpredictable errors and even loss of connectivity for some period of time Note that such behavior can be observed both for RF links such as IEEE and PLC links that exhibit similar behaviors Another characteristic of IP smart objects is that node failures for example due to energy depletion are significantly more frequent than in traditional IP networks where nodes are main powered highly redundant multi processors supporting non stop forwarding Another key characteristic is that LLNs do need to scale Some LLNs can be made of dozens and even hundreds of thousands of nodes This explains why specifying protocols for very large scale constrained and unstable environments bring its own sets of challenges For the sake of illustration other topics are discussed later one of the golden rules was to under react to failure by contrast with routing protocols such as OSPF or ISIS where the network needs to re converge within a few dozens of milliseconds This required a real paradigm shift since over reaction would lead to network collapse very rapidly Furthermore control plane overhead had to be minimized while supporting dynamic link node metrics MTR and so forth With these physical constraints and requirements this paper provides a rough first draft at describing the challenges in securing both LLNs and IP smart objects
4 pages
English
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