Cycle Solutions Research Articles

Basal channels on ice shelves

Recent surveys of floating ice shelves associated with Pine Island Glacier (Antarctica) and Petermann Glacier (Greenland) indicate that there are channels incised upward into their bottoms that may serve as the conduits of meltwater outflow from the sub‐ice‐shelf cavity. The formation of the channels, their evolution over time, and their impact on ice‐shelf flow are investigated using a fully‐coupled ice‐shelf/sub‐ice‐shelf ocean model. The model simulations suggest that channels may form spontaneously in response to meltwater plume flow initiated at the grounding line if there are relatively high melt rates and if there is transverse to ice‐flow variability in ice‐shelf thickness. Typical channels formed in the simulations have a width of about 1–3 km and a vertical relief of about 100–200 m. Melt rates and sea‐water transport in the channels are significantly higher than on the smooth flat ice bottom between the channels. The melt channels develop through melting, deformation, and advection with ice‐shelf flow. Simulations suggest that both steady state and cyclic state solutions are possible depending on conditions along the lateral ice‐shelf boundaries. This peculiar dynamics of the system has strong implications on the interpretation of observations. The richness of channel morphology and evolution seen in this study suggests that further observations and theoretical analysis are imperative for understanding ice‐shelf behavior in warm oceanic conditions.

Molar Heat Capacity (Cp) of Aqueous Cyclic Amine Solutions from (298.15 to 353.15) K

Molar heat capacities at 11 different temperatures in the range (298.15 to 353.15) K are reported for aqueous 1,4-dimethyl piperazine (1,4-DMPZ), 1-(2-hydroxyethyl) piperazine (1,2-HEPZ), 1-methyl piperazine (1-MPZ), 3-morpholinopropyl amine (3-MOPA), and 4-(2-hydroxyethyl) morpholine (4,2-HEMO) solutions. Molar heat capacities of MDEA and MEA were also measured and compared with published data resulting in a 1 % experimental uncertainty. Molar excess heat capacities were correlated as a function of mole fraction and temperature employing the Redlich–Kister relation. Excess partial molar quantities were calculated and reported. Group additivity analysis was performed using the molar heat capacities for all the above cyclic amines, and data were fitted with less than 0.5 AAD%. Among the five amines studied, 3-MOPA had the highest values of molar heat capacity and 1-MPZ had the lowest. The values of molar heat capacity of amines were dominated by −CH2 and −OH group contributions. The contributions of −CH2, −N, −OH, −O, and −NH2 groups increased with increasing temperature, and the contributions of −NH and −CH3 groups decreased with increasing temperature for these cyclic amines.

Hamiltonian Cycle Systems Which Are Both Cyclic and Symmetric

AbstractThe notion of a symmetric Hamiltonian cycle system (HCS) of a graph Γ has been introduced and studied by J. Akiyama, M. Kobayashi, and G. Nakamura [J Combin Des 12 (2004), 39–45] for , by R. A. Brualdi and M. W. Schroeder [J Combin Des 19 (2011), 1–15] for , and then naturally extended by V. Chitra and A. Muthusamy [Discussiones Mathematicae Graph Theory, to appear] to the multigraphs and . In each case, there must be an involutory permutation ψ of the vertices fixing all the cycles of the HCS and at most one vertex. Furthermore, for , this ψ should be precisely the permutation switching all pairs of endpoints of the edges of I.An HCS is cyclic if it is invariant under some cyclic permutation of all the vertices. The existence question for a cyclic HCS of has been completely solved by Jordon and Morris [Discrete Math (2008), 2440–2449]—and we note that their cyclic construction is also symmetric for (mod 8). It is then natural to study the existence problem of an HCS of a graph or multigraph Γ as above which is both cyclic and symmetric. In this paper, we completely solve this problem: in the case of even order, the final answer is that cyclicity and symmetry can always cohabit when a cyclic solution exists. On the other hand, imposing that a cyclic HCS of odd order is also symmetric is very restrictive; we prove in fact that an HCS of with both properties exists if and only if is a prime.

Solution space of Bianchi type I spacetime in loop quantum cosmology

We investigate the detailed structure of the solution space of the Bianchi type I spacetime with a massless scalar field in loop quantum cosmology (LQC). To analyze the dynamics we use the effective Hamiltonian written by new gauge-invariant variables which have a more direct physical interpretation. Since the effective equations of motion contain a nontrivial quantum correction, we may regard the universes as classical when the dynamics is well-described by the classical Friedmann equation. In addition to solutions which evolve into the classical universes, we find cyclic and stationary solutions which are dominated by the quantum effect for all time. We also show the asymmetric behavior and completely classify the Kasner transition across the bounce moment. We calculate the ``probability'' of having a classical isotropic universe by using the measure defined by the volume form in the solution space. Although we find that isotropic classical universes are disfavored in our model with a massless scalar field, we argue that LQC can explain the present isotropy if we consider a more realistic model.

Archimedean-type force in a cosmic dark fluid. III. Big rip, little rip, and cyclic solutions

We analyze late-time evolution of the Universe in the framework of the self-consistent model, in which the dark matter is influenced by the Archimedean-type force proportional to the four-gradient of the dark energy pressure. The dark energy is considered as a fluid with the equation of state of the relaxation type, which takes into account a retardation of the dark energy response to the Universe accelerated expansion. The dark matter is guided by the Archimedean-type force, which redistributes the total energy of the dark fluid between two its constituents, dark energy and dark matter, in the course of the Universe accelerated expansion. We focus on the constraints for the dark energy relaxation time parameter, for the dark energy equation of state parameter, and for the Archimedean-type coupling constants, which guarantee the Big Rip avoidance. In particular, we show that the Archimedean-type coupling protects the Universe from the Big Rip scenario with asymptotically infinite negative dark energy pressure, and that the Little Rip is the fate of the Universe with the Archimedean-type interaction inside the dark fluid.

Cyclic universe with an inflationary phase from a cosmological model with real gas quintessence

Phase-plane stability analysis of a dynamical system describing the Universe as a two-fraction fluid containing baryonic dust and real virial gas quintessence is presented. Existence of a stable periodic solution experiencing inflationary periods is shown. A van der Waals quintessence model is revisited and cyclic Universe solution again found.

Using a nonlinear dynamic model for prospective balancing of the demand and offer of goods produced by the power industry

The problem of prospective balancing the demand and offer of goods produced by the power industry is solved on the basis of a dynamic self-oscillating model. The existence of limit cycles, i.e., periodic cyclic solutions for the gross internal energy product that do not depend on the initial conditions, is proven.

A new approach to reconstruction methods in f(R) gravity

We present a new approach of the reconstruction method based on the use of the cosmic parameters instead of a time law for the scale factor. This solution generating technique allows the derivation and analysis of a set of new non-trivial exact cosmological solutions for f(R)-gravity. Specifically, we find two new cyclic solutions and we re-obtain a characteristic solution found also in the classical Starobinsky's model of higher order inflation.

Brahmagupta, mathematician par excellence

Brahmagupta holds a unique position in the history of Ancient Indian Mathematics. He contributed such elegant results to Geometry and Number Theory that today’s mathematicians still marvel at their originality. His theorems leading to the calculation of the circumradius of a triangle and the lengths of the diagonals of a cyclic quadrilateral, construction of a rational cyclic quadrilateral and integer solutions to a single second degree equation are certainly the hallmarks of a genius.

Effect of Amiloride to Retinal Toxicity Induced by Tissue Plasminogen Activator

PurposeThe effects of amiloride on cellular toxicity caused by tissue plasminogen activator (tPA) in mouse primary retinal cells were investigated.MethodsPrimary retinal cell cultures were maintained using glial conditioned medium. Commercial tPA and L-arginine were added, and the level of cyclic guanosine monophosphate (cyclic-GMP) in the culture supernatant was assessed using an ELISA assay. We measured the cell viability of cultured retinal cells pretreated with three different concentrations of amiloride (1, 10, and 100 µm) in addition to commercial tPA or L-arginine treatment.ResultsAfter exposing the cultured mouse retinal cells to tPA plus L-arginine or L-arginine alone, cyclic-GMP concentrations were 61.9 ± 5.1 pmole/mL and 63.1 ± 6.1 pmole/mL, respectively. However, the control group had a significantly lower concentration of cyclic-GMP (37.2 ± 3.4 pmole/mL, p < 0.01). The cyclic GMP-dissolved solution did not cause retinal cell death. In the control group and the group treated with 1 µm amiloride and tPA containing L-arginine, the cell viability was 43.7% and 44.5%, respectively. However, cell viability increased to 70.6% with 10 µm amiloride and 78.4% with 100 µm amiloride (p = 0.015).ConclusionsL-arginine increases intracellular cyclic-GMP and may give rise to retinal cells through this mechanism. In addition, amiloride in concentrations greater than 10 µm protects against L-arginine-induced retinal cell death.

Distribution Network Reconfiguration Based on Differential Evolution Algorithm

According to the configuration of distribution network, this paper put forward the corresponding cyclic decimal coding solution and corresponding mutation, crossover and selection strategy according to problems that during the distribution network reconfiguration, large number of infeasible solutions are produced. Furthermore, we gave the definition of radial decision problem, and solve the reverse problem of the first and the end nodes after reconstruction. The experimental results of the methods of IEEE33 and PG&E69 node simulation show that this method can effectively solve the problem.

Analytical evaluation of the nonlinear vibration of a solid circular sector object

This paper applied a new class of critical technique for resolution of the cyclic solutions nonlinear called the HE’s variational approach method (VAM) to solve the nonlinear vibration of a solid circular sector object. In variational approach, only one repetition leads to high exactness of the solutions, as opposed to the other methods. It has been found that the variational approach is very prolific, rapid, functional and does not demand small perturbation and is also sufficiently accurate to both linear and nonlinear problems in engineering. The obtained consequences show that the approximate solutions are uniformly legitimate on the whole solution field in comparison with the numerical solution using Runge-Kutta method. VAM could simply be enlarged to other powerfully non-natural oscillations and it could be found widely feasible in engineering and science. Key words: Runge-Kutta method, solid circular sector object, variational approach method.

Geodesically complete analytic solutions for a cyclic universe

We present analytic solutions to a class of cosmological models described by a canonical scalar field minimally coupled to gravity and experiencing self interactions through a hyperbolic potential. Using models and methods inspired by 2T-physics, we show how analytic solutions can be obtained in flat/open/closed Friedmann-Robertson-Walker universes. Among the analytic solutions, there are many interesting geodesically complete cyclic solutions in which the universe bounces at either zero or finite sizes. When geodesic completeness is imposed, it restricts models and their parameters to a certain parameter subspace, including some quantization conditions on initial conditions in the case of zero-size bounces, but no conditions on initial conditions for the case of finite-size bounces. We will explain the theoretical origin of our model from the point of view of 2T-gravity as well as from the point of view of the colliding branes scenario in the context of M-theory. We will indicate how to associate solutions of the quantum Wheeler-deWitt equation with our classical analytic solutions, mention some physical aspects of the cyclic solutions, and outline future directions.

Non-steroidal anti-inflammatory drug diflunisal interacting with Cu(II). Structure and biological features

Copper(II) complexes with the non-steroidal anti-inflammatory drug diflunisal in the presence of N,N-dimethylformamide or nitrogen donor heterocyclic ligands (pyridine, 1,10-phenanthroline, 2,2′-bipyridine or 2,2′-bipyridylamine) have been synthesized and characterized. The deprotonated diflunisal ligands are coordinated to Cu(II) ion through carboxylato oxygen atoms. The crystal structures of [tetrakis(diflunisal)bis(N,N-dimethylformamide)dicopper(II)] 1 and [bis(diflunisal)bis(pyridine)copper(II)], 2 have been determined by X-ray crystallography and are the first reported crystal structures of diflunisal complexes. UV study of the interaction of the complexes with calf-thymus DNA (CT DNA) suggests binding of the complexes to CT DNA with the dinuclear [tetrakis(diflunisal)bis(N,N-dimethylformamide)dicopper(II)] compound exhibiting the highest binding constant, K b. Intercalative binding mode may also be concluded using cyclic voltammetry and solution viscosity measurements of the complexes in the presence of CT DNA. Competitive studies with ethidium bromide (EB) indicate that the complexes can displace the DNA-bound EB suggesting competition with EB. Diflunisal and its complexes exhibit good binding propensity to human or bovine serum albumin protein showing relatively high binding constant values.

Synthesis of poly-Lysine/Gold nanoparticle films and their electrocatalytic properties

Films composed of citrate stabilized gold nanoparticles (AuNPs) and Poly-Lysine (pLys) were fabricated by electropolymerization on glassy carbon (GC) electrodes from 0.1M phosphate buffer solution at pH = 8. The films were topographically analyzed by atomic force microcopy whereas their electrocatalytic properties were studied by cyclic voltammetry and electrochemical impedance spectroscopy in aqueous solution using 0.0005M [Fe(CN)6] 3-/4- as redox probes and 0.1M NaClO4 as supporting electrolyte. The electron transfer process proved to be more efficient at the pLys-AuNP modified electrodes containing low amounts of gold nanoparticles (500 µL, 2.5×10-4M) than at the bare glassy carbon electrode. The heterogeneous electron transfer constant increased 2 orders of magnitude at the pLys-AuNP modified electrodes proving a more efficient electron transfer than at bare GC. These new films have a great potential for DNA biosensor applications.

Conditional Fredholm determinant for the S-periodic orbits in Hamiltonian systems

For S being a symplectic orthogonal matrix on R 2 n , the S-periodic orbits in Hamiltonian systems are a solution which satisfies x ( 0 ) = S x ( T ) for some period T. This paper is devoted to establishing the theory of conditional Fredholm determinant in studying the S-periodic orbits in Hamiltonian systems. First, we study the property of the conditional Fredholm determinant, such as the Fréchet differentiability, the splittingness for the cyclic type symmetric solutions. Also, we generalize the Hill formula originally gotten by Hill and Poincaré. More precisely, let M be the monodromy matrix of the S-periodic orbits, then we get the formula relating the characteristic polynomial of the matrix SM and the conditional Fredhom determinant. Moreover, we study the relation of the conditional Fredholm determinant and the relative Morse index. Applications to the problem of linear stability for the S-periodic orbits are given.

Optimality of impulse harvesting policies

We explore the link between cyclical and smooth resource exploitation. We define an impulse control framework which can generate both cyclical solutions and steady-state solutions. Our model can admit convex and concave profit functions and allows the integration of different stock-dependent profit functions. We show that the strict concavity of the profit function is only a special case of a more general condition, related to submodularity, that ensures the existence of optimal cyclical policies. We then establish a link with the discrete-time models with cyclical solutions by Benhabib and Nishimura (J Econ Theory 35:284–306, 1985) and Dawid and Kopel (J Econ Theory 76:272–297, 1997). For the steady-state solution, we explore the relation to Clark’s (1976) continuous control model.

Partial Molar Volumes and Partial Molar Isentropic Compressions of γ-Butyrolactone and ε-Caprolactone at Infinite Dilution in Water at Temperatures (278.15 to 318.15) K and at Atmospheric Pressure

Density and speed-of-sound values at T = (278.15, 283.15, 288.15, 293.15, 298.15, 308.15, and 318.15) K and at atmospheric pressure were measured, for dilute aqueous solutions of γ-butyrolactone and e-caprolactone, using an Anton Paar DSA 5000 vibrating-tube densimeter and sound analyzer. A small but significant effect of hydrolysis was observed for aqueous e-caprolactone and a procedure for eliminating its effect was proposed and employed. Values of the partial molar volume and isentropic compression at infinite dilution were obtained from this experimental data by suitable extrapolation procedures and compared with available data from the literature. The group contribution of the methylene group was evaluated and compared with that obtained for other classes of aqueous cyclic solutes.

Lyapunov stability of economically oriented NMPC for cyclic processes

Abstract Several applications in process industries, such as simulated moving bed (SMB) separation and pressure swing adsorption (PSA), exhibit cyclic steady state behavior. Moreover, it is of economic interest to require energy intensive applications to take advantage of the periodically varying electricity price by changing the operating point frequently. Because traditional two-layer optimization methods are difficult to apply to these systems, we consider instead an economically oriented nonlinear model predictive control (NMPC) that directly considers system’s economic performance subject to the dynamic model. On the other hand, the commonly used Lyapunov framework to analyze the stability for the economically oriented NMPC cannot be applied directly. This work proposes two economically oriented NMPC formulations and proves nominal stability for both. We introduce transformed systems by subtracting the optimal cyclic steady state from the original system, for which the Lyapunov function can easily be established. Moreover, we show that the asymptotical stability of the transformed system is equivalent to that of the original system. Hence, the original systems are also nominally stable at the cyclic optimal solution. Finally, an industrial size air separation unit case study with periodic electricity cost is presented.

Fabrication and mechanical properties of homogeneous zirconia toughened alumina ceramics via cyclic solution infiltration and in situ precipitation

Alumina ceramic composites toughened with various contents of fine-sized zirconia particulates were fabricated via cyclic infiltrating pre-sintered alumina preforms with zirconium oxychloride solution and immersion in ammonia solution to induce in situ precipitation. Homogeneous distribution of zirconia throughout the bulk material has been substantiated by line-scan analysis and backscattering images taken from sections with different distances from surface. It was found that a higher drying temperature and increase in infiltration numbers lead to a greater zirconia content and bigger grain size. The hardness of fabricated zirconia toughened alumina composite was firstly improved probably due to the microstructure refining effect, while a further increase in zirconia content results in the decrease of hardness. A significantly higher indentation toughness has been observed for samples containing >10 wt.% zirconia compared with other specimens, which could be attributed to the coarser zirconia grain size and the related greater tendency to transformation into monoclinic phase.