Simple Duct Research Articles

Identification of Secretory Compounds from the European Callipodidan Species Apfelbeckia insculpta

Defensive secretions of the callipodidan species Apfelbeckia insculpta contain a p-cresol as the main component and phenol in traces. This is the first identification of these compounds in a European callipodidan species. The repugnatory glands of A. insculpta are of the spirobolid type and consist of a spherical reservoir, a simple duct, and a valvular cuticular infolding that opens onto the lateral surface of the millipede via a pore.

From frequency to time domain: Signal features and physical characteristics for resonant acoustical systems

The determination of the impulse response or the reflection function of an acoustical system from data expressed in the frequency domain is not immediate. Signal processing from frequency domain to time domain should involve phenomena of large amplitude as oscillations known as "ripple" that does not correspond to any physical phenomenon. The "ripple phenomenon" will be analyzed from both a signal processing and a physical point of view with the help of simple duct acoustic examples. A map designed as a new time‐frequency tool helps us to show that it cannot be removed in most cases without the use of processing techniques involving modifications in the computed signal. This work has been developed for the automotive research, but can be applied to musical acoustics or to any field connected with time domain exploration of acoustic cues.

Adaptive active attenuation of noise using multiple model approaches

The adaptive active noise control problem is considered, in which the response of the system under control varies with time. A new algorithm for system identification in such circumstances, using multiple models of the secondary path transfer function, is presented. The computational burden of the proposed algorithm can be much smaller than the existing methods, particularly in the multi-channel case. An infinite impulse response structure is assumed for the control filter, and the recursive least mean square algorithm introduced by Feintuch is used to adjust the filter coefficients. By combining the proposed identification technique and the filtered-x recursive least mean square algorithm, the multiple model adaptive controller for active noise control problems is presented. This method requires a prioriinformation about the plant to select models of the secondary path transfer function, so it can be used when we have some information on the plant and operating situations. Computer simulations were performed to show the effectiveness of the proposed algorithm in a simple duct problem.

Anatomy of the Major Lacrimal Gland of Rhesus Monkeys (Macaca mulatta)

The major lacrimal gland of rhesus monkeys is impalpable within the fatty connective tissue of the upper lateral quadrant of the orbit. Acini of the lacrimal glands are composed of both sparsely and heavily granulated cells that histochemically resemble serous acinar cells of the submandibular salivary gland. The cytoplasmic granules are strongly periodic acid-Schiff (PAS)-positive, and some are also stained by alcian blue for acidic mucosubstances. The lacrimal gland has a simple duct system of intralobular ducts and interlobular excretory ducts. Lymphocytes and plasma cells are common in the periductal stroma. Major lacrimal glands of rhesus monkeys are suitable for comparative and correlative studies of lacrimal and salivary diseases and radiation responses.

NUMERICAL CALCULATION OF TURBULENT OPEN-CHANNEL FLOWS BY USING A MODIFIED κ-ε TURBULENCE MODEL

Numerical calculation techniques of turbulent shear flows are classified into two categories: one is κ-e turbulence model and the other is large eddy simulation (LES). The standard κ-e model has been established at present to predict turbulent structure in closed duct flows, while LES is being developed to predict coherent eddy structure in more simple duct flows. The standard κ-e model cannot be, however, applied to open channel surface flows, because the turbulence near the free surface is more depressed than the closed duct flows.In the present study a new modified κ-e model is proposed to predict reasonably the turbulent structure in open channel flows with both of low and high Reynolds numbers. The numerical calculations indicate a splendid agreement with the experimental data which were obtained by making use of hot-film and Laser Doppler anemometers.

The anatomy of Addisonia (Mollusca, Gastropoda)

The organization of Addisonia lateralis (Requien, 1848) and A. brophyi McLean, 1985 is described. Addisonia species have a thin, asymmetrical, cup-like shell and a very simple shell muscle. Eyes, oral lappets and epipodial tentacles are absent and the right cephalic tentacle is also used as a copulatory organ. Most characteristic is the enormously developed gill which is enlarged into the right subpallial cavity. It is composed of about 30 leaflets with skeletal rods and its epithelia are uniquely arranged. The heart is large and the single auricle is situated anteriorly left. There are two kidneys: the left is small, while the right forms large coelomic cavities and has no connection with the pericardium or the hermaphroditic genital system. Testis and ovary are separate: both have a simple duct proper (vas deferens, oviduct). They are connected to the copulatory organ by an open seminal groove; a small receptaculum is present. The mouth opening is typically triangular, with no jaws or subradular sense organs. Addisonia possesses tuft-like salivary glands, a radula diverticulum and distinct, tubular oesophageal glands. The oesophagus itself is simple. The radula and the posterior alimentary tract are unique; the stomach is completely reduced and the intestine forms a pseudostomach. The streptoneurous, hyoathroid nervous system has pedal cords with three commissures. The visceral loop is also cord-like. A single (left) osphradium is present and the small statocysts have several statocones. The peculiarities and unique combination of primitive and advanced characters in Addisonia reflect a highly enigmatic organization among the Archaeogastropoda. Possible relationships to other archaeogastropod groups are discussed.

Morphology of the intercapsular segment of the oviduct in the golden hamster with special reference to ovum-transit from ruptured follicles to the ampulla.

The intercapsular segment of the oviduct in the golden hamster is not a simple duct which has constant outer and inner diameters. After penetrating the bursa ovarica the ICS has a circular constriction and the corresponding oviductal lumen is narrowed.

Research Note: A Twin-Rotor Cross-Flow Fan

A twin-rotor cross-flow fan, having two parallel-axis contra-rotating impellers at the entrance to a simple rectangular duct, is found to have a longer stable operating characteristic than an equivalent single-rotor fan.

The Shock Tube

In recent years interest has been revived in an apparatus which was first developed more than fifty years ago. This apparatus, which is known today as a shock tube, is a very useful research tool, the versatility of which is not generally appreciated in this country. In this paper the author attempts to give a clear physical description of the flow in a shock tube and a review of the problems which may be investigated by means of this apparatus.Basically, a shock tube consists of a simple fabricated duct which may be closed or open at one end, and closed at the other end. A diaphragm divides this duct into two compartments which initially contain gases at different pressures. In a conventional shock tube the cross-section is constant, the ends are closed, and air is used on both sides of the diaphragm (Fig. 1).

Studies on Acholic Cachexia: IV. Relation of Biliary Diversion to Duodenal Ulcer Formation.

The occurrence of peptic ulcer of the duodenum after the exclusion of bile has been noted with a wide variation in frequency and the factors concerned are not clearly understood. Kapsinow and Harvey,1 using a cholecystnephrostomy, produced ulcer in 17 out of 43 animals. Bollman and Mann2 by simply ligating the common ducts produced ulceration in about 60%. In the experiments of Berg and Jobling3 in which a Rous type of fistula was used, ulcers resulted in 13 of 23. Kim and Ivy report 10% ulcers in one series4 in which the common duct was tied, but 60% in cases of Rous fistula.Besides the obvious acid factor, there is considerable evidence that other influences are at work. Ivy has suggested that the mechanical irritation of the tubing near the duodenum may be important. On the other hand Elman has seen but few ulcers resulting from bile fistula alone. Our own experience has been that simple duct ligature alone caused ulceration in numbers about one-half the rate usually suggested (60%), but that a very hi...