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The equivalent conductances of aqueous solutions of sodium decanoate, sodium laurate, and sodium myristate have been determined from the very dilute region up to saturation concentration, at 25O and 35". The limiting conductances have been obtained from the measurements in the usual way. In addition and for the sake of completeness, the limiting equivalent conductances of sodium formate, sodium acetate, sodium propionate, and sodium butyrate have also been determined a t 35O, since they were not known a t this temperature.The effect of increasing chain length on mobility is discussed. From a consideration of the experimental and the theoretical values of the slopes of the plots of equivalent conductance against the square root of the concentration, it is concluded that some sort of interaction, possibly a reversible dimerization of anions, occurs, even in the dilute region, and this could account for the lower experimental values of the slope. This phenomenon has been observed with other long chain electrolytes, however, and the hypothesis of dimerization is not the only possible one.The critical micelle concentrations have been determined, and recent concepts of micelle formation are applied to interpret their structure. The surface tensions of the aqueous solutions have been measured a t 25O and 50".The object of this work has been described in a previous publication (I). We have now extended our work to include the decanoate, laurate, and myristate ions (14 carbons, including the carboxyl group) and this is about as far as there is any point in going. In addition, however, to our interest in the limiting conductance of the anion, it was found that the slope of the conductance curve, in the very dilute region, is not that of the Onsager theory, when the number of carbon atoms exceeds six. This phenomenon has been observed by others and it points to peculiarities in the structure of solutions of these salts. Moreover, since the soap-like character of the solutions of these sodium salts is very marked, we were obliged t o investigate other physical properties, notably the surface tension. EXPERIMENTAL Our method of determining conductances has been described previously (1). Densities were determined with Ostwald-Sprengel pycnometers, cap. 2.5 ml, and the usual precautions with respect to bouyancy, etc., were taken. The densities are correct to f 0.0001. Viscosities were determined with the Cannon and Fenske modification of the Ostwald viscometer. The stalagmometer method was used to determine surface tension. T o obtain a sufficient degree of accuracy, it was necessary to count from 100 t o 200 drops but, because these soap-like solutions are sometimes very viscous, this laborious operation could occupy a s much as 3 h. An automatic system was therefore desired. Each drop as it fell from the stalagmometer fell into a glass cone, having platinum plates on opposite sides: these plates were connected to a n electronic glow counter. The glow counter was enclosed in a Faraday cage to eliminate signal pickup.T...

The properties of NaN03, NaC104, and NaCNS in concentrated aqueous solutions have been investigated at 25" by the techniques of electrical conductance, diffusion (Stokes' diaphragm technique), viscosity, and density, and the comparison of these with those of NaCl (as model electrolyte) is reported. In addition to the analytical characterization, the data are examined as an indication of ion-ion and solvation type interactions, and structural transitions in very concentrated salt solutions.

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Research Council of the National Academy of Sciences-National Academy of Engineering provides. These services are organized under an overall Review Committee which considers the program as a whole and makes recommendations on policy, long-term planning, and international collaboration. Advisory Panels, each concerned with a single technical area, meet regularly to examine major portions of the program, assign relative priorities, and identify specific key problems in need of further attention. For selected specific topics, the Advisory Panels sponsor subpanels which make detailed studies of users' needs, the present state of knowledge, and existing data resources as a basis for recommending one or more data compilation activities. This assembly of advisory services contributes greatly to the guidance of NSRDS activities. The NSRDS-NBS series of publications is intended primarily to include evaluated reference data and critical reviews of long-term interest to the scientific and technical community.

No abstract

Wave-pipelining enables a digital circuit to be operated at a higher frequency. In the literature, only trial-and-error and manual procedures are adopted for the choice of the optimum value of clock frequency and clock skew between the input and output registers of wave-pipelined circuits. One of the major contributions of this paper is the proposal for automating the above procedure. A second contribution is the study of how logic depths determine the superiority of wave-pipelining over pipelining with regard to power dissipation. For the study and implementation of wave-pipelined circuits, filters using the distributed arithmetic algorithm are considered. In this paper, two automation schemes are proposed for the implementation of the wave-pipelined filters on both Xilinx and Altera field programmable gate arrays (FPGAs). In the first scheme, a self-tuning finite state machine (FSM) is used to choose the clock skew and clock period for I/O registers between the wave-pipelined blocks. In the second approach, an on-chip soft-core processor is used to choose the clock skew and clock period. To test the efficacy of the schemes proposed, filters with different taps are implemented using three schemes: synchronous pipelining, sub-optimal wave-pipelining and no pipelining (i.e. using neither synchronous pipelining nor wave-pipelining). From the implementation results, it is observed that wave-pipelined distributed arithmetic (DA) filters are faster by a factor of 1.31-1.61 compared to non-pipelined DA filters. The synchronous pipelined DA filters are in turn faster by a factor of 1.73-3.27 compared to the wave-pipelined DA filters. The This work is carried out with the funding received from the 262 Circuits Syst Signal Process (2008) 27: 261-276 increased speeds are achieved in the pipelined filters at the cost of an increase in the number of slices by 15-33% and in the number of registers by 350-530%. To compare the power dissipation, both pipelined and wave-pipelined DA filters are tested by operating them at the same frequency. For medium logic depths, the wave-pipelined DA filters dissipate less power than pipelined filters.

Application mapping of disseminated intellectual property into Network on Chip (NoC) is a well-defined NP-Hard problem. Improvement of network performance in NoC is purely based on an effective mapping approach with cost and performance metrics optimization which includes area, power, delay, reliability, and thermal distribution. A self-adaptive mapping approach for NoC is proposed in this paper. In this method, the self-adaptive chicken swarm optimization algorithm (SCSO) is used for an effective mapping, which has never been applied with NoC. The proposed method reduces the power consumption of NoC through a cognitive base using shared K-nearest neighbor clustering method and it offers faster mapping over standard and randomly generated benchmarks. The experimental results indicate that the proposed method outperforms existing bio-inspired metaheuristic algorithms, especially for large application graph. INDEX TERMS Network on chip, self-adaptive chicken swarm optimization, shared K-nearest neighbor clustering, bio-inspired metaheuristic algorithm.