Republican Remedies

Since its founding of the republic, Americans have devised a variety of different ways to reconcile unity with depth, separation with checks, and presidentialism with republicanism. This chapter surveys the succession of informal institutional and organizational improvisations that periodically altered practical working relationships within the American constitutional system. These extra-constitutional contrivances created several distinctive “systems” of administration, each of which preserved the republican idea of inter-branch collaboration. Nineteenth-century remedies were party-based; twentieth-century remedies were administration-based. The move from one system to the next marked a profound change in the operation of government at large, but at every turn, a more powerful presidency was corralled into novel arrangements that reaffirmed collective responsibility. The origins of our beleaguered republic lay in the 1970s, when that spirit of accommodation began to break down. Presidents grew more independent in their political and institutional powers, and they asserted their right to unitary control over the executive branch more vigorously. In the congressional pushback, collaboration gave way to a constitutional face-off.

Wave Propagation in Periodic Metallic Structures with Equilateral Triangular Holes

This paper studies wave propagation in a periodic parallel-plate waveguide with equilateral triangular holes. A mode-matching method is implemented to analyze the dispersion diagram of the structure possessing glide and mirror symmetries. Both structures present an unexpected high degree of isotropy, despite the triangle not being symmetric with respect to rotations of 90°. We give some physical insight on the matter by carrying out a modal decomposition of the total field on the hole and identifying the most significant modes. Additionally, we demonstrate that the electrical size of the triangular hole plays a fundamental role in the physical mechanism that causes that isotropic behavior. Finally, we characterize the influence of the different geometrical parameters that conform the unit cell (period, triangle size, hole depth, separation between metallic plates). The glide-symmetric configuration offers higher equivalent refractive indexes and widens the stopband compared to the mirror-symmetric configuration. We show that the stopband is wider as the triangle size is bigger, unlike holey structures composed of circular and elliptical holes where an optimal hole size exists.

Propagation of Torsional Surface Waves in a Nonhomogeneous Half-Space With Circular Irregularity in Free Surface

The present paper studies the effect of circular regularity on propagation of torsional surface waves in an elastic non-homogeneous half-space. Both rigidity and density of the half-space are assumed to vary inversely linearly with depth. Separation of variable method has been used to get the analytical solutions for the dispersion equation of the torsional surface waves. Also, the effects of non-homogeneity and irregularity on the phase velocity of torsional surface waves have shown graphically.

Modelling One-Dimensional Fractional Impact Using Basic Fractional Viscoelastic Models

Viscoelastic materials can be mathematically represented using integer- or order models. It has been shown in different studies that modeling a viscoelastic material usually requires an enormous number of parameters. Fractional viscoelastic models have been shown to be advantageous over integer viscoelastic models in the representation of viscoelastic materials, specifically when the system has memory or hereditary property. However, to the authors’ knowledge, no study has yet been done about fractional impact models. Thus, in this paper, fractional modified Kelvin-Voigt model and fractional Maxwell model are introduced as one-dimensional fractional impact models for basic fractional viscoelastic materials. The force-displacement hysteresis curves are obtained by using the fractional Chebyshev collocation method and the gradient of impact force, penetration depth, separation depth, and the coefficient of restitution are studies. It is shown numerically that fractional viscoelastic models behave more realistic than their integer counterparts in one-dimensional impact problems.

Solving Stereo Transparency with an Extended Coarse-to-Fine Disparity Energy Model

Modeling stereo transparency with physiologically plausible mechanisms is challenging because in such frameworks, large receptive fields mix up overlapping disparities, whereas small receptive fields can reliably compute only small disparities. It seems necessary to combine information across scales. A coarse-to-fine disparity energy model, with both position- and phase-shift receptive fields, has already been proposed. However, because each scale decodes only one disparity for each location and uses the decoded disparity to select cells at the next scale, this model cannot represent overlapping surfaces at different depths. We have extended the model to solve stereo transparency. First, we introduce multiplicative connections from cells at one scale to the next to implement coarse-to-fine computation. The connection is the strongest when the presynaptic cell’s preferred disparity matches the postsynaptic cell’s position-shift parameter, encouraging the next scale to encode residual disparities with the more reliable phase-shift mechanism. This modification not only eliminates the artificial decoding and selection steps of the original model but also enables maintenance of complete population responses throughout the coarse-to-fine process. Second, because of this modification, explicit decoding is no longer necessary but rather is for visualization only. We use a simple threshold criterion to decode multiple disparities from population energy responses instead of a single disparity in the original model. We demonstrate our model using simulations on a variety of transparent and nontransparent stereograms. The model also reproduces psychophysically observed disparity interactions (averaging, thickening, attraction, and repulsion) as the depth separation between two overlapping planes varies.

The Simulation Experiments Research of Plow Bit Cutting Coal Rock Basing on Ls-Dyna

Using finite element analysis software ANSYS/ LS-DYNA, establishing the plow cutting coal seam 3D simulation model, simulating plow bit cutting coal seam dynamic process. under study, obtaining plow bit the cutting resistance, plow speed of time process curve, analyzing the influence on cutting energy consumption of the different cutting depth, separation distance and width, reaching the rule of cutting energy consumption changing with plow bits’ structure parameter and design parameters, in order to reduce the energy consumption and resistance, cutting depth and plow bits spacing ought to be selected by the real coal seam face conditions.

The Finite Element Simulation Study on Plow Bit’s Resistance during Cutting Coal and Rock

Establishing the plow cutting coal seam 3D simulation model, Using finite element analysis software ANSYS/ LS-DYNA, simulating plow bit cutting coal seam process. under Through this study, obtaining the plow speed, cutting resistance of plow bit’s time process curve, analyzing the influence on cutting resistance of different cutting depth, separation distance and width.

Size-structured risk assessments govern Daphnia migration

One of the more fascinating phenomena in nature is animal mass migrations and in oceans and freshwaters, diel variations in depth distribution of zooplankton are a phenomenon that has intrigued scientists for more than a century. In our study, we show that zooplankton are able to assess the threat level of ultraviolet radiation and adjust their depth distribution to this level at a very fine tuned scale. Moreover, predation risk induces a size-structured depth separation, such that small individuals, which we show are less vulnerable to predation than larger, make a risk assessment and continue feeding in surface waters during day, offering a competitive release from down-migrating larger animals. Hence, we mechanistically show that such simple organisms as invertebrate zooplankton are able to make individual, size-specific decisions regarding how to compromise between threats from both predators and UV radiation, and adjust their diel migratory patterns accordingly.