An experimental investigation of two-dimensional thrust augmenting ejectors, part 2

The flow-field within a two-dimensional thrust augmenting ejector has been documented experimentally. Results are presented on the mean velocity field and the turbulent correlations by Laser Doppler Velocimeter, surface pressure distribution, surface temperature distribution, and thrust performance for two shroud geometries. The maximum primary nozzle pressure ratio tested was 3.0. The tests were conducted at primary nozzle temperature ratios of 1.0, 1.8 and 2.7. Two ejector characteristic lengths have been identified based on the dynamics of the ejector flow field, i.e., a minimum length L sub m below which no significant mixing occurs, and a critical length L sub c associated with the development of U'V' correlation in the ejector. These characteristic lengths divide the ejector flow field into three distinctive regions: the entrance region where there is no direct interaction between the primary flow and the ejector shroud; the interaction region where there is an increased momentum of induced flow near the shroud surface; and a pipe flow region characterized by an increased skin friction where x is the distance downstream from the ejector inlet. The effect of the coflowing induced flow has been shown to produce inside the ejector a centerline velocity that has increased over the free-jet data

The Philippines: External Shocks, Adjustment Policies and Impact on Selected Development Concerns, 1973-1985

With the objective of designing and implementing more effective policies and programs in the light of external shocks, this paper assesses the impact of economic crisis and adjustment policies on basic economic and social concerns particularly on vulnerable income groups. The development path implied in this article is a strategy that is expansionary within the limits set by external finance and other policy considerations.vulnerable groups, adjustment policies

Mapped Null Hypersurfaces and Legendrian Maps

For an $(m+1)$-dimensional space-time $(X^{m+1}, g),$ define a mapped null hypersurface to be a smooth map $\nu:N^{m}\to X^{m+1}$ (that is not necessarily an immersion) such that there exists a smooth field of null lines along $\nu$ that are both tangent and $g$-orthogonal to $\nu.$ We study relations between mapped null hypersurfaces and Legendrian maps to the spherical cotangent bundle $ST^*M$ of an immersed spacelike hypersurface $\mu:M^m\to X^{m+1}.$ We show that a Legendrian map \wt \lambda: L^{m-1}\to (ST^*M)^{2m-1} defines a mapped null hypersurface in $X.$ On the other hand, the intersection of a mapped null hypersurface $\nu:N^m\to X^{m+1}$ with an immersed spacelike hypersurface $\mu':M'^m\to X^{m+1}$ defines a Legendrian map to the spherical cotangent bundle $ST^*M'.$ This map is a Legendrian immersion if $\nu$ came from a Legendrian immersion to $ST^*M$ for some immersed spacelike hypersurface $\mu:M^m\to X^{m+1}.$Comment: 13 pages, 1 figur

Egg Parasitoids of Proconiini (Hemiptera: Cicadellidae) in Northwestern Mexico, with Description of a New Species of Gonatocerus (Hymenoptera: Mymaridae)

Nine species of Mymaridae and Trichogrammatidae parasitic on eggs of Proconiini sharpshooters (Cicadellidae: Cicadellinae) were collected in northwestern Mexico in relation to neoclassical biological control efforts against glassy-winged sharpshooter, Homalodisca vitripennis (Germar), in California. Gonatocerus chula Triapitsyn and Bernal sp. n., which belongs to the ater species group of Gonatocerus Nees (Mymaridae), is described. Specimens of G. chula sp. n. were reared from eggs of the smoke-tree sharpshooter, Homalodisca liturata Ball, on jojoba [Simmondsia chinensis (Link) C. K. Schneider] leaves collected in central Sonora state, Mexico. Also given are new data on other egg parasitoids of Homalodisca spp. and Oncometopia spp. in Sinaloa and Sonora states, Mexico, including Gonatocerus atriclavus Girault, G. morrilli (Howard), and G. novifasciatus Girault, and the Trichogrammatidae Burksiella sp(p)., Ittys sp., Pseudoligosita sp., Ufens ceratus Owen, and U. principalis Owen. For the first time, a species of Ittys is recorded from eggs of Proconiini, and U. principalis from Mexico. Colonies of G. atriclavus, G. novifasciatus and Pseudoligosita sp. were successfully established in a quarantine laboratory at University of California, Riverside, on eggs of the glassy-winged sharpshooter. These three parasitoid species had never been reared under laboratory conditions. In addition, seven species of Proconiini were collected in central and northwestern Mexico: Cyrtodisca major (Signoret), Homalodisca insolita (Walker), H. liturata Ball, Oncometopia sp. cf. clarior (Walker), O. sp. cf. trilobata Melichar, O. (Similitopia) sp., and Phera centrolineata (Signoret). Oncometopia sp. cf. clarior, O. sp. cf. trilobata, and O. (Similitopia) sp. appeared to be undescribed species

Linking and causality in globally hyperbolic spacetimes

The linking number $lk$ is defined if link components are zero homologous. Our affine linking invariant $alk$ generalizes $lk$ to the case of linked submanifolds with arbitrary homology classes. We apply $alk$ to the study of causality in Lorentz manifolds. Let $M^m$ be a spacelike Cauchy surface in a globally hyperbolic spacetime $(X^{m+1}, g)$. The spherical cotangent bundle $ST^*M$ is identified with the space $N$ of all null geodesics in $(X,g).$ Hence the set of null geodesics passing through a point $x\in X$ gives an embedded $(m-1)$-sphere $S_x$ in $N=ST^*M$ called the sky of $x.$ Low observed that if the link $(S_x, S_y)$ is nontrivial, then $x,y\in X$ are causally related. This motivated the problem (communicated by Penrose) on the Arnold's 1998 problem list to apply link theory to the study of causality. The spheres $S_x$ are isotopic to fibers of $(ST^*M)^{2m-1}\to M^m.$ They are nonzero homologous and $lk(S_x,S_y)$ is undefined when $M$ is closed, while $alk(S_x, S_y)$ is well defined. Moreover, $alk(S_x, S_y)\in Z$ if $M$ is not an odd-dimensional rational homology sphere. We give a formula for the increment of \alk under passages through Arnold dangerous tangencies. If $(X,g)$ is such that $alk$ takes values in $\Z$ and $g$ is conformal to $g'$ having all the timelike sectional curvatures nonnegative, then $x, y\in X$ are causally related if and only if $alk(S_x,S_y)\neq 0$. We show that $x,y$ in nonrefocussing $(X, g)$ are causally unrelated iff $(S_x, S_y)$ can be deformed to a pair of $S^{m-1}$-fibers of $ST^*M\to M$ by an isotopy through skies. Low showed that if (\ss, g) is refocussing, then $M$ is compact. We show that the universal cover of $M$ is also compact.Comment: We added: Theorem 11.5 saying that a Cauchy surface in a refocussing space time has finite pi_1; changed Theorem 7.5 to be in terms of conformal classes of Lorentz metrics and did a few more changes. 45 pages, 3 figures. A part of the paper (several results of sections 4,5,6,9,10) is an extension and development of our work math.GT/0207219 in the context of Lorentzian geometry. The results of sections 7,8,11,12 and Appendix B are ne

Quantum effects on Higgs-strahlung events at Linear Colliders within the general 2HDM

The associated production of neutral Higgs bosons with the Z gauge boson is investigated in the context of the future linear colliders, such as the ILC and CLIC, within the general two-Higgs-doublet model (2HDM). We compute the corresponding production cross-sections at one-loop, in full consistency with the available theoretical and phenomenological constraints. We find that the wave-function renormalization corrections to the external Higgs fields are the dominant source of the quantum effects, which turn out to be large and negative, and located predominantly in the region around \tan\beta=1 and moderate values of the parameter \lambda_5 (being \lambda_5 < 0). This behavior can be ultimately traced back to the enhancement potential of the triple Higgs boson self-couplings, a trademark feature of the 2HDM with no counterpart in the Higgs sector of the Minimal Supersymmetric Standard Model. The predicted Higgs-strahlung rates comfortably reach a few tens of femtobarn, which means barely 10^3 - 10^4 events per 500 inverse femtobarn of integrated luminosity. Due to their great complementarity, we argue that the combined analysis of the Higgs-strahlung events and the previously computed one-loop Higgs-pair production processes could be instrumental to probe the structure of the Higgs sector at future linac facilities.Comment: LaTeX, 16 pages, 9 Figures, 2 Tables. Extended discussion, references added, matches published version in Phys. Rev.