Aerodynamical Investigations on Reaction Turbine Blades

So far no theory of the Reaction Turbine has as yet been investigated which is capable of clarifying fully the effect of such factors as the number of blades, the blade angle, the blade pitch and the breadth of the blade upon the action of these machines. It Is known that the "lift" of biplanes and triplanes per unit of wing surface is Inferior to that of a monoplane, and that the degree of departure depends upon the gap-chord ratio. Published data indicate that the lift increases with increasing gap, apparently towards some limiting value. Regarding steam turbine wheels as rings of multiplanes, it may be asked "Is there any direct evidence that the torque on each blade Is influenced by the presence of the other blades?" Many experiments have been made to determine the optimum circumferential pitch for a given blade shape, but most of these have aimed simply at arriving empirically at the best efficiency, without inquiry into the factors involved. The present investigations were carried out on Model Reaction Blades reproduced several times the actual full size so that the Reynold's number is maintained at a value of interest in turbine design, but with comparatively low air speeds usual in WIND TUNNEL work, to examine the effects of the number of blades, the blade pitch and the blade angle

Accelerating Asymptotically Exact MCMC for Computationally Intensive Models via Local Approximations

We construct a new framework for accelerating Markov chain Monte Carlo in posterior sampling problems where standard methods are limited by the computational cost of the likelihood, or of numerical models embedded therein. Our approach introduces local approximations of these models into the Metropolis-Hastings kernel, borrowing ideas from deterministic approximation theory, optimization, and experimental design. Previous efforts at integrating approximate models into inference typically sacrifice either the sampler's exactness or efficiency; our work seeks to address these limitations by exploiting useful convergence characteristics of local approximations. We prove the ergodicity of our approximate Markov chain, showing that it samples asymptotically from the \emph{exact} posterior distribution of interest. We describe variations of the algorithm that employ either local polynomial approximations or local Gaussian process regressors. Our theoretical results reinforce the key observation underlying this paper: when the likelihood has some \emph{local} regularity, the number of model evaluations per MCMC step can be greatly reduced without biasing the Monte Carlo average. Numerical experiments demonstrate multiple order-of-magnitude reductions in the number of forward model evaluations used in representative ODE and PDE inference problems, with both synthetic and real data.Comment: A major update of the theory and example

Which one is better: presentation-based or content-based math search?

Mathematical content is a valuable information source and retrieving this content has become an important issue. This paper compares two searching strategies for math expressions: presentation-based and content-based approaches. Presentation-based search uses state-of-the-art math search system while content-based search uses semantic enrichment of math expressions to convert math expressions into their content forms and searching is done using these content-based expressions. By considering the meaning of math expressions, the quality of search system is improved over presentation-based systems

Long Term Culture of Hepatocytes of Some Fish Species of the Chesapeake Bay

The liver is an important site of metabolism and effects of toxic chemicals. This makes it an important organ for tumorigenesis studies. This study was aimed at investigating the optimal culture characteristics of liver cells derived from some indigenous Chesapeake Bay fish species. Hepatocytes from Atlantic -menhaden (Brevootia tyraMus), toadfish (Opsanus tau), croaker (Micropogonius undulatus), and hogchocker (Trinectes maculatus) were isolated using an enzymatic dispersion technique. The highest yield was obtained from toadfish livers (14.9±5. lx 1 o5 cells/g oflive weight) and the lowest was from the croaker (5.9±3. lx 1 o5 cells/g of live body weight). The percentage of hepatocytes in cell preparations exceeded 90% except for the toadfish liver cells preparation (82.3%). Freshly isolated hepatocytes were globular with irregular contour and occurred as individual cells or small clusters of 2-30 cells. A confluent monolayer of attached cells was obtained after two weeks of incubation. An osmolality of 325 m Osm/kg best supported the multiplication of hepatocytes of the four fish species. While the optimum temperature for hogchocker and toadfish hepatocytes appeared to be 33oC; it ranged from 21-27oC for menhaden and croaker. The medium that best supported the growth of culture The potential of long term hepatocyte culture using fish of Chesapeake Bay will enable further studies on the activation and detoxification processes of xenobiotics and, therefore, help in understanding pollution related neoplasia and diseaseshttps://scholarworks.wm.edu/vimsbooks/1181/thumbnail.jp

Generalized β\beta-conformal change and special Finsler spaces

In this paper, we investigate the change of Finslr metrics $$L(x,y) \to\bar{L}(x,y) = f(e^{\sigma(x)}L(x,y),\beta(x,y)),$$ which we refer to as a generalized $\beta$-conformal change. Under this change, we study some special Finsler spaces, namely, quasi C-reducible, semi C-reducible, C-reducible, $C_2$-like, $S_3$-like and $S_4$-like Finsler spaces. We also obtain the transformation of the T-tensor under this change and study some interesting special cases. We then impose a certain condition on the generalized $\beta$-conformal change, which we call the b-condition, and investigate the geometric consequences of such condition. Finally, we give the conditions under which a generalized $\beta$-conformal change is projective and generalize some known results in the literature.Comment: References added, some modifications are performed, LateX file, 24 page

Recent Advances in Non-Linear Site Response Analysis

Studies of earthquakes over the last 50 years and the examination of dynamic soil behavior reveal that soil behavior is highly nonlinear and hysteretic even at small strains. Non-linear behavior of soils during a seismic event has a predominant role in current site response analysis. The pioneering work of H. B. Seed and I. M. Idriss during the late 1960’s introduced modern site response analysis techniques. Since then significant efforts have been made to more accurately represent the non-linear behavior of soils during earthquake loading. This paper reviews recent advances in the field of non-linear site response analysis with a focus on 1-D site response analysis commonly used in engineering practice. The paper describes developments of material models for both total and effective stress considerations as well as the challenges of capturing the measured small and large strain damping within these models. Finally, inverse analysis approaches are reviewed in which measurements from vertical arrays are employed to improve material models. This includes parametric and non-parametric system identification approaches as well as the use of Self Learning Simulations to extract the underlying dynamic soil behavior unconstrained by prior assumptions of soil behavior

A Survey on Retrieval of Mathematical Knowledge

We present a short survey of the literature on indexing and retrieval of mathematical knowledge, with pointers to 72 papers and tentative taxonomies of both retrieval problems and recurring techniques.Comment: CICM 2015, 20 page

On Finslerized Absolute Parallelism spaces

The aim of the present paper is to construct and investigate a Finsler structure within the framework of a Generalized Absolute Parallelism space (GAP-space). The Finsler structure is obtained from the vector fields forming the parallelization of the GAP-space. The resulting space, which we refer to as a Finslerized Parallelizable space, combines within its geometric structure the simplicity of GAP-geometry and the richness of Finsler geometry, hence is potentially more suitable for applications and especially for describing physical phenomena. A study of the geometry of the two structures and their interrelation is carried out. Five connections are introduced and their torsion and curvature tensors derived. Some special Finslerized Parallelizable spaces are singled out. One of the main reasons to introduce this new space is that both Absolute Parallelism and Finsler geometries have proved effective in the formulation of physical theories, so it is worthy to try to build a more general geometric structure that would share the benefits of both geometries.Comment: Some references added and others removed, PACS2010, Typos corrected, Amendemrnts and revisions performe

Myringoplasty in children: Retrospective analysis of 60 cases

Myringoplasty or type 1 tympanoplasty aims the restoration of the anatomic integrity of the tympanic membrane; it's a very common surgery in otology. The objective was to evaluate the anatomic and functional results of this surgery in children using the retro-auricular approach. Sixty young patients with diagnosis of simple tympanic perforation were evaluated; these patients underwent myringoplasty by a retro-auricular approach (underlay technique) between November 2010 and May 2013. It's a retrospective evaluation of the anatomic and functional results of theses myringoplasties. Mean age at surgery was 8, 5 years old, cartilage was used as graft in our entire patient, closure of perforation was successful in 48 cases (80%), and audiometric results showed functional improvement in 27 (45%) patients, no significant change was noted in the remaining patients. The results of myringoplasty in children seem worse than those in adults. However, a large study with a long follow up is warranted in order to come to definitive conclusions