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41.
The application of barrier discharges at atmospheric pressure in air expands on the market of plasma technology, because it is an ecological and cost‐effective alternative to other processes of surface treatment. These plasmas usually consist of a multitude of spatially and temporally localized filaments, whose distribution should be as even as possible for homogeneous treatment. This holds especially for the plasma treatment of sensitive goods such as wool or other textiles. In equipment for continuous pass of material the barrier arrangements often consist of a system cylinder – cylinder or cylinder – plane, whereby the gap width changes locally. Space distribution and intensity of filaments has been investigated by means of short‐time photography and spatially resolved measurement of current distribution and energy distribution derived from it. The local dependency found can be explained by means of a capacitive equivalent circuit. 相似文献
42.
Real-time multimedia applications have to use forward error correction (FEC) anderror concealment techniques to cope with
losses in today’s best-effort Internet. The efficiency of these solutions is known however to depend on the correlation between
losses in the media stream. In this paper we investigate how the packet size distribution affects the packet loss process,
that is, the distribution of the number of lost packets in a block, the related FEC performance and the average loss run length.
We present mathematical models for the loss process of the MMPP+M/D/1/K and the MMPP+M/M/1/K queues; we validate the models
via simulations, and compare the results to simulation results with an MPEG-4 coded video trace. We conclude that the deterministic
packet size distribution (PSD) not only results in lower stationary loss probability than the exponential one, but also gives
a less correlated loss process, both at a particular average link load and at a particular stationary loss probability as
seen by the media stream.Our results show that for applications that can only measure the packet loss probability, the effects
of the PSD on FEC performance are higher in access networks, where a single multimedia stream might affect the multiplexing
behavior. Our results show that the effects of the PSD on FEC performance are higher in access networks, where a single multimedia
stream might affect the multiplexing behavior and thus can improve the queuing performance by decreasing the variance of its
PSD. 相似文献
43.
44.
Electro-organic synthesis without supporting electrolyte: Possibilities of solid polymer electrolyte technology 总被引:1,自引:0,他引:1
J. Jörissen 《Journal of Applied Electrochemistry》2003,33(10):969-977
The application of ion exchange membranes as solid polymer electrolytes (SPE) in fuel cells is state-of-the-art. This technology needs no supporting electrolyte; consequently it can be applied for electro-organic syntheses in order to save process steps. In this case the process is not predetermined to a maximized energy efficiency so that the selection of the cell design, of the electrode materials and of the operating conditions can be focused on a high selectivity of the electrode reactions. The electro-osmotic stream, which is caused by the solvation shells of the ions during their migration through the membrane, and hence is a typical property of SPE technology, has a significant effect on the electrode reactions. It generates enhanced mass transfer at the electrodes, which is beneficial for reaction selectivity. It can be influenced by the choice of, and possibly by the preparation of, the membrane. An additional remarkable advantage of SPE technology is the exceptional long durability of oxide coated electrodes. By combination of several process engineering methods stable operation of SPE cells has been realized, even for examples of non-aqueous reaction systems. Experiments up to 6000 h duration and in cells of up to 250 cm2 membrane area show the potential for industrial application. 相似文献
45.
Björn Täljsten 《International Journal of Fracture》1996,82(3):253-266
This paper presents the use of fracture mechanics for the plate bonding technique. Plates of steel or carbon-fibre reinforced
plastic are bonded with an epoxy adhesive to rectangular concrete prisms and loaded in shear up to failure, what is normally
known in fracture mechanics as mode II failure. In this special application a linear and a nonlinear approach are presented.
The nonlinear equation derived for a realistic shear-deformation curve can only be used for numerical calculations. However,
for simplified shear-deformation curves, the derived formula can be solved analytically. Results from tests, which are compared
with the theory, are also presented. 相似文献
46.
Depletion and hillock formation were examined in-situ in a scanning electron microscope (SEM) during electromigration of bamboo
Al interconnect segments. Hillocks formed directly at the anode ends of the segments by epitaxial addition of Al at the bottom
Al/TiN interface. Depletion occurred nonuniformly from the cathode end and stopped once the distance between the leading void
and the hillock reached the critical length for electromigration at the given current density. A modified equation for the
drift velocity is proposed, which includes the effect of nonuniform depletion and predicts that interconnects with nonuniform
depletion are more reliable than those with uniform depletion. 相似文献
47.
T. Herrmannsdörfer J. Friebel F. Pobell J. Mrachkov M. Kirov E. Leyarovski 《Journal of Low Temperature Physics》1997,107(1-2):209-224
We have measured the 16 Hz susceptibility of the diluted Van Vleck paramagnets Pr1−x
Y
x
Ni5 withx=0.00, 0.05, 0.10. 0.20 at temperatures 1.5 K≤T≤50 K and magnetic fields up to 15T. Their Van Vleck type magnetic susceptibility χ(T, B, x) strongly depends on the field atB≥6 T. The temperatureT
max(B, x) of the maximum of χ(T, B, x) decreases at increasing the field from zero to 15 T by approximately one order of magnitude for all Pr1−x
Y
x
Ni5 compounds. Changing the dilutionx from zero to 0.20, the field whereT
max(B, x) strongly drops is increased from 9 T to 11 T. Our data agree qualitatively with the predictions of a point charge model
which considers the Zeeman term in addition to the electronic exchange and the dominating crystal field contributions. 相似文献
48.
Olaf Strelow 《Forschung im Ingenieurwesen》1997,63(9):255-261
A general method for calculating any heat exchanger network is presented. As heat exchanger networks can be considered as coupled heat exchangers, that are supplied in a predetermined order, it is convenient to consider even a single heat exchanger with complicated flow patterns as a network composed of several ideally-supplied, coupled devices. The advantage of this method lies in its higher accuracy and the use of a simpler calculation formula for an ideal device model. These advantages far outweigh the disadvantages of the arduous iterative type of calculation used to establish the temperature between ideal devices. The presented method allows, for the first time, without using the iterative method, a calculation of heat exchanger networks based upon the principle of coupled matrix equations. These equations are for any given heat exchanger network simply allocated parameters, and therefore this method is especially suited for the calculation of any network modification. For the application of this method is no special software necessary. The solution of the model equations is obtained very easy and clear with mathematical standard software, e.g. Mathcad or Maple. 相似文献
49.
50.
Summary Starting with Z-2, 3-diamino-2-butenedinitrile as diamine component the synthesis of the low molecular N,N,O,O-chelate 3.Co and its ligand 3 is optimized. An easy synthesis of the chelate 8.Co covalently bound on macroreticular resins is presented. The chelates 8.Co are the most active heterogenous catalysts for the valence isomerization of quadricyclane to norbornadiene today. 相似文献