MULTIPLE FLAG IND-VARIETIES WITH FINITELY MANY ORBITS

Let G be one of the ind-groups GL(∞), O(∞), Sp(∞), and let P1, ..., Pℓ be an arbitrary set of ℓ splitting parabolic subgroups of G. We determine all such sets with the property that G acts with finitely many orbits on the ind-variety X1 × × Xℓ where Xi = G/Pi. In the case of a finite-dimensional classical linear algebraic group G, the analogous problem has been solved in a sequence of papers of Littelmann, Magyar–Weyman–Zelevinsky and Matsuki. An essential difference from the finite-dimensional case is that already for ℓ = 2, the condition that G acts on X1 × X2 with finitely many orbits is a rather restrictive condition on the pair P1, P2. We describe this condition explicitly. Using the description we tackle the most interesting case where ℓ = 3, and present the answer in the form of a table. For ℓ ≥ 4 there always are infinitely many G-orbits on X1 × × Xℓ.

Recoverability and Expectations-Driven Fluctuations

Time series methods for identifying structural economic disturbances often require disturbances to satisfy technical conditions that can be inconsistent with economic theory. We propose replacing these conditions with a less restrictive condition called recoverability, which only requires that the disturbances can be inferred from the observable variables. As an application, we show how shifting attention to recoverability makes it possible to construct new identifying restrictions for technological and expectational disturbances. In a vector autoregressive example using postwar U.S. data, these restrictions imply that independent disturbances to expectations about future technology are a major driver of business cycles.

Certain cases of elastic equilibrium of a composed wedge with an interface crack

Problems of interface cracks starting from the common corner points of pairs of perfectly glued wedges of different isotropic elastic materials are addressed. It is demonstrated that for a few particular configurations and a restrictive condition imposed on values of elastic constants (corresponding to vanishing of the second Dundurs parameter), the problem of elastic equilibrium may be solved by Khrapkov’s method. These configurations are: (i) the wedges forming a half-plane; (ii) the wedges forming a plane; (iii) one of the wedges being a half-plane. In all cases, the external boundaries are supposed to be free of stresses. By applying Mellin’s transform for all three configurations the problem has been reduced to vector Riemann’s problem, and the matrix coefficient has been factorized for the case of the mentioned restrictive condition. The first configuration, i.e. the problem of an inclined edge crack located along the boundary separating two wedges of different elastic isotropic materials forming a half-plane is considered in more detail. The solution has been obtained for both uniform (corresponding to remote loading) and non-uniform (loading applied at the crack faces) problems. Numerical results are presented and compared with the available results obtained by other authors for particular cases. The obtained solutions appear especially valuable for analysing extreme cases of parameters.

Strengthening the impairment argument against abortion

Perry Hendricks’ impairment argument for the immorality of abortion is based on two premises: first, impairing a fetus with fetal alcohol syndrome (FAS) is immoral, and second, if impairing an organism to some degree is immoral, then ceteris paribus, impairing it to a higher degree is also immoral. He calls this the impairment principle (TIP). Since abortion impairs a fetus to a higher degree than FAS, it follows from these two premises that abortion is immoral. Critics have focussed on the ceteris paribus clause of TIP, which requires that the relevant details surrounding each impairment be sufficiently similar. In this article, we show that the ceteris paribus clause is superfluous, and by replacing it with a more restrictive condition, the impairment argument is considerably strengthened.

On the universal texture in the PA-2HDM for the V-spin case

In a version of the PA-2HDM where only mixing between third and second fermion generations is allowed, we propose a mechanism to generate the second Yukawa matrix through a Unitary V-spin flavor transformation on the mass matrix for quarks and leptons. This flavor structure is constrained to be universal, that is, we use the same parameters to generate Yukawa matrix elements in the quark and leptonic sectors, reducing drastically the number of free parameters of the PA-2HDM. As a consequence of this restrictive condition, we obtain relations between the Yukawa matrix elements, that we call the Universal Texture Constraint (UTC). We obtained an interval of values for the second Yukawa matrix elements, expressed in terms of the Cheng and Sher ansatz, for [Formula: see text] and [Formula: see text] coming from the UTC and experimental bounds for light scalar masses. Finally, we find the allowed parameter region when the experimental bounds and values for [Formula: see text] decays, [Formula: see text] mixing, [Formula: see text] and [Formula: see text] are considered.

Combined Cycle Units for Terrestrial Propulsion - Dimensional Approach

High performances and operation with low water consumption are mandatory but not sufficient conditions for the Combined Cycles Units implementation in the terrestrial propulsion systems field. There is another restrictive condition, which refers on the admitted size. That is why a dimensional analysis of the Combined Cycles Units is mandatory. In this view, paper presents the results of the dimensional analysis of a small scale Combined Cycles Unit for terrestrial propulsion, based on a two-pressure-levels Steam Cycle and operating with liquid fuel.

FURTHER GEOMETRIC RESTRICTIONS ON JORDAN STRUCTURE IN MATRIX FACTORIZATION

It is known that a nonsingular, nonscalar, n-by-n complex matrix A may be factored as A = BC, in which the spectra of B and C are arbitrary, subject to det (A) = det (B) det (C). It has been shown that when two matrices have eigenvalues of high geometric multiplicity, this restricts the possible Jordan structure of the third. We demonstrate a previously unknown restriction on the Jordan structures of B and C. Furthermore, we show that this generalized geometric multiplicity restriction implies the already known geometric multiplicity restriction, show that the new more restrictive condition is not sufficient in general but is sufficient in a situation that we identify.

A Study on UCAV Flight Control System Based on Jamming Observer

In order to study the uncertain nonlinear jamming problem in UCAV’s flight control system, a method using jamming observer to check the system’s jamming was designed. Based on jamming observer, a flight control law was constructed, which reduced the restrictive condition for the jamming. The simulation results show that the adaptive flight control law based on jamming observer, make UCAV’s flight control system have good stability and robustness, it’s a great convenience analyzing the system stability.