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1.
Atlanta is perhaps the city with the greatest degree of black political empowerment (BPE) in the United States. Yet in 2009 a relatively weak white mayoral candidate nearly won the general and runoff elections over a field of stronger black candidates. Why? Treating Atlanta as a prototypical case, the article examines factors that undermine the capacity of blacks to retain control of mayoralties in strong BPE cities, with an emphasis on disruptions to black electorates, discontent among black citizens, and reinvestment in electoral politics by whites at the local level. 相似文献
2.
Stability and boundedness conditions of pulse modulated feedback systems are derived in this paper. These conditions, based on the frequency domain approach, extend the range of applicability of this approach to systems without the strict sector non-linearity. Geometric interpretations of the results in the Popov plane are also presented. 相似文献
3.
JACOB HAMMER 《International journal of control》2013,86(5):1981-1990
The problem of constructing right-coprime fraction representations is considered for non-linear discrete-time systems possessing a continuous realization. It is shown that, given a static, possibly non-additive, state feedback that stabilizes the input/state part of the realization, a right-coprime fraction representation of the entire system can be constructed. The resulting coprime fraction representation has a particularly simple factorization space, and can be used to derive stabilizing controllers for the original system without state access. The construction of appropriate static state feedbacks is described in a companion paper (Hammer 1989 b). 相似文献
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5.
The effect of natural convection on forced convection in a horizontal flow was investigated during zinc electrodeposition on a horizontal electrode facing upward in a channel. The previous findings of Tobias and Hickman [1] are confirmed. A secondary flow in the form of roll cells whose axes are parallel to the flow direction is formed at some distance from the leading edge. This distance depends linearly on the flow velocity through the critical Rayleigh number for the onset of natural convection across the diffusion boundary layer. Striated zinc deposits reveal the imprint of the secondary flow on the planar cathode facing upward. 相似文献
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Using calf rennet or a commercial microbial rennet substitute derived from Rhizomucor miehei cheesemaking experiments were performed at laboratory and pilot scale, and at commercial scale in two industrial dairy plants during regular production. At all levels of scale, the solids transfer from milk to curd was significantly higher (0.50–1.19%) when using calf rennet. There were significant differences in levels of proteolysis during maturation and in levels of bitterness at 12 weeks of ripening between Gouda cheeses produced with calf rennet or with commercial rennet substitute at pilot and at commercial scale. 相似文献
8.
Composite Ag(Br,I) tabular microcrystals of photographic emulsions were studied by the combination of energy-filtering electron microscopy (EFTEM) and electron energy-loss spectroscopy (EELS) in conjunction with energy-dispersive X-ray (EDX) microanalysis. The contrast tuning under the energy-filtering in the low-loss region was used to observe more clearly edge and random dislocations, {11− 1} stacking faults in the grain shells parallel to {11− 2} edges and bend and edge contours. Electron spectroscopic diffraction patterns revealed numerous extra reflections at commensurate positions in between the Bragg reflections and diffuse honeycomb contours; these were assigned to the number of defects in the shell region parallel to the grain edges and polyhedral clusters of interstitial silver cations, respectively. Inner-shell excitation bands of silver halide were detected and confirmed by EDX analyses, i.e. the Ag N2,3 edge at 62 eV (probably overlapped with the weak I N4,5 edge at 52 eV and the Br M4,5 edge at 70 eV), the I M4,5 edge at about 620 eV, and the Br L2,3 edge at about 1550 eV energy losses. Energy-loss near-edge structure of the Ag M4,5 edge at about 367 eV energy losses and low-loss fine structure arisen as a result of interband transitions and excitons, possibly superimposed with many electron effects, have been revealed. The crystal thickness was determined by a modified EELS log-ratio technique in satisfactory agreement with measurements on grain replicas. 相似文献
9.
JACOB FISH RAVI GUTTAL 《International journal for numerical methods in engineering》1997,40(10):1767-1784
An adaptive solver for large-scale hierarchic finite element systems has been developed. A decision-making methodology aimed at selecting an optimal solution strategy on the basis of estimated conditioning, sparsity and memory requirements for a given problem has been devised. Numerical experiments have been conducted on selected shell and 3-D problems in the range of 1000–100 000 degrees of freedom. © 1997 by John Wiley & Sons, Ltd. 相似文献
10.
In power system studies, congestion in transmission lines and utilization of flexible alternating current transmission system (FACTS) devices are closely associated. These devices are very important due to their role in power delivery system enhancement. It is to be noted that the generation companies can exercise their market power which depends on the line flows, line constraints, generators’ location and its share to the individual loads. This issue cannot be overlooked as it creates monopoliness which is against the deregulated market policy. The objective of this paper is to study the impact of market power when FACTS devices like thyristor controlled switching capacitor (TCSC) and thyristor controlled phase angle regulator (TCPAR) are used under steady state operation. The market power is determined using nodal must-run share (NMRS) index for the standard IEEE 14-bus system with and without the above FACTS devices and the results obtained are compared. All the above simulations are conducted in a MATLAB 7.9-R2009b environment. 相似文献