In order to realize two-dimensional lithography at high resolution (several tens of nanometres), a new approach to the lithography of a fine pattern using a confined etchant layer technique (CELT) in an electrochemical system is presented. A mould plate of conductive material with a highresolution line pattern (which can be prepared with the aid of e.g. electron beams) is used instead of the tip in scanning tunnelling microscopy (STM). The etchant species is generated at the surface of the mould plate by electrochemical photochemical or photoelectrochemical methods, then diffuses away from the surface of the mould plate. The key feature of CELT is the design of a chemical reaction which rapidly destroys the etchant (e.g. within microseconds on average) following its generation. Therefore, the gradient of the concentration of etchant can be greatly enhanced and the thickness of the diffusion layer can be greatly decreased to several tens of nanometres. Thus, the etchant layer is confined and its outer boundary can essentially retain the fine structure of the pattern of the mould plate. Then the substrate to be corroded is adjusted by ECSTM to approach the mould plate within several tens of nanometres and the corroded pattern can retain the fine structure giving a resolution of several tens of nanometres.

Cryst. Res. Technol. 341999 1 71-88Starting from the origin and the informational content of Kossel interferences excited by electron and synchrotron radiation beams selected examples of microstructural applications, such as the precision determination of lattice constants, the precision determination of crystallographic orientation of single grains, the determination of local stresses/strains and the determination of tetragonal distortions of cubic lattices including the description of a variety of methods for analysis are presented.Ausgehend vom Prinzip der Entstehung und des Informationsgehaltes von elektronenstrahl-bzw. synchrotronstrahlangeregten Kossel-Aufnahmen werden Auswertungsmethoden und Anwendungen im Mikrobereich, wie die Präzisionsgitterkonstantenbestimmung, die Einzelkorn-Orientierungsbestimmung, die Eigenspannungsanalyse sowie die Diagnose von Abweichungen von der kubischen Symmetrie an ausgewählten Beispielen beschrieben.

Vehicle-to-vehicle (V2V) communication empowers vehicles to share information by broadcasting basic and critical safety messages. Dedicated short-range communication (DSRC), the medium access control (MAC) layer of which utilizes the IEEE 802.11p protocol, is a promising candidate technology for vehicular communication. Safety applications usually demand safety message dissemination to be prompt and reliable. To satisfy these strict requirements, the MAC layer of vehicular safety communication tends to adopt Distributed Coordination Function (DCF) or single-class Enhanced Distributed Channel Access (EDCA) without request-to-send/clear-to-send (RTS/CTS), acknowledgment (ACK) and retransmission mechanisms as the access scheme. As far as we know, although many numerical models have been provided to understand the IEEE 802.11 DCF performance, there is no precise model that examines the performance of vehicular safety communication exploiting such an access scheme in imperfect channels with different incoming traffic loads. In this paper, we settle this problem by developing an analytical model where the impacts of various incoming traffic loads, packet length distribution, hidden terminal effects, node mobility, the MAC layer queuing system, and the faulty radio channels are all included which no one has done this before. The experimental and numerical results reveal that the constructed model can exactly forecast the vehicular network performance of packet delay, delivery rate, and reception rate under different traffic and channel circumstances.

In this paper, we design a mathematical model for performance and reliability evaluation of the IEEE 802.11p Enhanced Distributed Channel Access (EDCA) broadcast scheme in Dedicated Short-Range Communication (DSRC) with the presence of hidden terminals. Specifically, we first introduce a more accurate semi-Markov process (SMP) model to portray the channel contention among multiple types of safety messages and their backoff behavior in DSRC based vehicular ad hoc networks (VANETs) with the influence of hidden terminals. Each type of safety message's generation and service in an individual vehicular node is modeled leveraging a unique M/G/1/K queue. For the channel contention, the SMP model interrelates with the M/G/1/K queue via fixed-point iteration. Additionally, grounded on the solution of fixed-point iteration, we acquire the performance indices such as packet delay (PD), packet delivery rate (PDR), and packet reception rate (PRR). The new SMP model considers the IEEE 802.11p EDCA backoff counter process, unsaturated packet arrivals, limited MAC queue length, hidden terminals, Nakagami-m fading channel with distance-related path loss, and distinct transmission, carrier sensing and interference ranges. Eventually, we validate the correctness of the model through the comparison between the numerical and simulation results under different network parameters and prove that the proposed model has an advantage over the existing models in analyzing the impact of hidden terminals on PDR and PRR.

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