Pocket Type Research Articles

A system for automatic extraction of 3D part features using syntactic pattern recognition techniques

This paper reports a system which employs string based syntactic pattern recognition techniques for feature extraction. A B-rep based solid model of the component is used for processing the face boundaries (loops) to derive boundary strings which are syntactically analysed to detect feature signatures. The detected signatures are geometrically verified, and the positional and dimensional parameters of the features are calculated. The system is capable of detecting features with complex cross sections; compound features which include nested and intersecting features; and various types of holes and pockets. These capabilities of the system make it an effective interface between a geometric solid modeller and various application programs.

Effects of the Feedline and the Hydrostatic Pocket Depth on the Flow Pattern and Pressure Distribution

The paper treats on a comparative basis the development of the flow and pressure maps in deep, and respectively, shallow hydrostatic bearing pockets. The numerical simulation uses a dimensionless formulation of the Navier-Stokes equations written for a body fitted coordinates system, and applied through a collocated grid. The present work is a continuation of the simulations performed by Braun et al. (1993, 1994a, 1994b) to cases where the length and diameter of the restrictor feedline is of consequence to the flow in both the shallow and the deep pocket. The model includes the coupling between the pocket flow and a finite length feedline flow, on one hand, and the pocket and the adjacent lands on the other hand. Geometrically, all pockets have the same projected footprint, lands length, and capillary feedline. This numerical study uses the Reynolds number Re based on the runner velocity (laminar range only), and the inlet jet strength F as the dynamic similarity parameters, while the dimensionless clearance C is used as a geometric parameter. The flow structures, and the physical reasons underlying the causes of the pressure variation inside the deep and shallow pockets [either longitudinally (radially) or transversally (circum-ferentially)], are discussed quantitatively and comparatively. It is further shown that the transversal pressure distributions under the runner are highly dependent on whether the flow is dominated by the rotation of the runner (hydrodynamic effects), or by the strength of the hydrostatic jet (F). Finally the longitudinal pressure curves in the depth of the pocket, and restrictor are presented and the nature of their variation discussed. The back step and Rayleigh step effects are also discussed on a comparative basis for the two types of pockets, and in conjunction with the Couette, and the jet dominated flow. The modification of the central vortical zones of the deep pockets into oblong vortical zones for the shallow pockets is presented, and its consequences are discussed.

Electron Tunneling Studies in the Charge Density Wave State of the Quasi Bidimensional Metal ?-Mo4O11

Electron tunneling studies have been performed on junctions made with the quasi bidimensional oxide η-Mo 4 O 11 and a lead film separated by an insulating oxide layer. The density of states in the vicinity of the Fermi level has been obtained along two directions (parallel and perpendicular to the layers) in the temperature range 1 K-90 K. The data from the differential conductance as a function of dc bias voltage are consistent with gap openings taking place at T p1 = 100 K and T p2 = 30 K. Both electron instabilities are attributed to charge density waves and the anisotropy of the density of states is related to the anisotropy of the Fermi surface. For tunneling current in the plane of the layers, weak oscillations are found in the density of states at low temperatures. They are possibly due to the existence of several types of small electron and hole pockets induced on the Fermi surface by the charge density wave gap openings

Association between mites and leaf domatia: evidence from Bangladesh, South Asia

ABSTRACTMites use the leaf domatia of many woody plant species in Australasia and North America. Different types of leaf domatia, including pits, pockets and tuft domatia, are present among plant species in disturbed forests, plantations and gardens of Bangladesh in South Asia. These structures are frequently occupied by mites. Pooling across all species, domatia were often (66%) occupied by mites and used by them for shelter, egg-laying and development. On average, 70% of all mites on leaves were found in domatia, and over three-quarters of these were potentially beneficial (i.e. of predaceous or microbivorous taxa) to the plant. Further, when species were pooled across sites, leaves of domatia-bearing plants had significantly more predaceous mites than those of plants without domatia. These results are consistent with the patterns of mite-domatia association reported in Australasia, North America and North Asia and with predictions of mutualism between plants and mites.

The role of principles and methods in loess-paleosol investigations

In the process of loessification, the development of loess fabric, the role of zonal, regional and partly of local environmental factors is regarded decisive. In the loess sequences various genetic types of loess pockets and paleosols occur and reflect different climatic and paleogeographical conditions.

Examination of Components of Variance for A Production Scale, Low Dose Powder Blend and Resulting Tablets

AbstractA study was performed to quantify the contributions of the different components comprising the total variance term observed following the analysis of content uniformity testing of powder blends and tablets. A full scale (400 kg) blend study was performed on a low dose tablet formulation (drug content = 0.13%). Content uniformity samples were pulled from throughout the blender using a pocket type probe thief in a manner which allowed the blend to be assessed for both homogeneity and sample to sample variability at a given location. Tablets were compressed from the batch and assayed for content uniformity. Sampling error accounted for approximately 75% of the variance observed following analysis of drug content in the powder blends. The estimated total variance for the powder blend was approximately twice that observed for tablets compressed from the mixture. The analytical contribution to the total variance term was minor. The difference between the estimated total variance terms for powder blend a...

GAUGE SENSITIVITY OPTIMIZATION IN AIR POCKET TENSIOMETRY

Potential applications of air pocket type tensiometers in measuring hydraulic head profiles in deep vadose zones are discussed. Advantages of this method include (i) the ability to obtain tensiometer measurements far beyond the approximately 9 m-depth often associated with the limit of conventional tensiometry, (ii) ease of regular gauge calibration, and (iii) low cost. Advantages relative to buried, dedicated pressure transducer tensiometers are gained at the expense of substantial losses in gauge sensitivity, S*. In view of this compromise, an analysis was performed to determine the optimal fractional water-filled length, F, for air pocket tensiometers. It is shown that the critical ratio governing the nature of S*-optimization is approximated by (II* - II{sub 0})/z* > 1, S* is optimized when F {yields} 1. However, when (II* - II{sub 0})/z* < 1, S* is optimized as F {yields} 0. The central role of (II* - II{sub 0})/z* arises from the fact that S* = P{sub a}/V{sub g}, where P{sub a} refers to the absolute pressure of all tensiometer headspace gases excluding water vapor, and V{sub g} refers to the volume of the gas phase within the tensiometer headspace. When (II* - II{sub 0}) is less than z*, S* goes to zeromore » because the absolute pressure in the tensiometer headspace approaches the vapor pressure of the tensiometer water (P{sub 0}) when attempts are made to fill the tensiometer column with liquid water. In the more familiar case of II* - II{sub 0} being larger than z*, the dominance of P{sub a} over P{sub 0} assures that S* increases as the instrument is filled. To test the predicted nature of S*, laboratory experiments were performed on 1.11-, 6.36-, and 11.91-m long tensiometers over a range of values of (II* - II{sub 0}) and F sufficient to provide three orders of magnitude variation in S*. 17 refs., 5 figs.« less

Sistemática, ecologia e zoogeografia dos Tropidurus do grupo Torquatus ao sul do Rio Amazonas (Sauria, Iguanidae)

This paper is a systematic revision of the lizards of the genus Tropidurus (torquatus group) occurring south of the Rio Amazonas. Following an analysis of meristic characters in five areas where lizards with different types of mite pockets occur synpatrically, eleven species are recognized, seven of which described as new. Diagnoses, descriptions and geographic distribution are given for each species, and an artificial key to species is presented. Ecologically, there seem to be two species assemblages: the first includes all species with wide geographic distribution, and the second includes species with restricted distributions, usually limited to mountain or sandy soil areas. Probably present climatic conditions are more suitable for the first group, than for the second. A model based on the geographic ecology of the recent past of a pair of species is proposed to explain the present complex distribution of some species of the torquatus group. The geographic differentiation of T. torquatus and T. hygomi is studied and a sequence of events proposed to explain its origin, ecologic differentiation and evolution.

Estimating Log Pearson Parameters by Mixed Moments

When applying the method of moments, parameters of log Pearson type 3 distribution (LP) can be estimated either from the moments of real data or from the moments of the logarithmic data, or by mixing the moments of real and log data. Mixed moments methods eliminate the use of sample skewness coefficient which is generally biased. By a previous study, the mixed moments method (MXM1) which uses the mean and variance of real data and the mean of log data was found to possess superior statistical properties, but the estimating procedure was tedious. This paper describes simplified approaches by which LP parameters, through the MXM1 method, can be obtained even by ordinary pocket type calculators. Practical examples are presented to illustrate the application of eight LP fitting methods.

Geographical heterochrony: Comtemporaneous coexistence of neogene and recent molluscan faunas in the Americas

Geographical heterochrony is a biogeographical pattern that, within a single faunal province, represents the contemporaneous coexistence of newly-evolved faunas and those which have persisted, unchanged, from earlier geological ages. This array of discrete, adjacent, and asynchronous faunules produces a mosaic pattern in both time and space. Based on the faunas of three anachronistic subregions within the Recent Caribbean Molluscan Province, one off the Yucatan Peninsula, one off Roatan Island, and one near the Gulf of Venezuela, this geographically heterochronous province is shown to contain two types of relict pockets. The term “primary relict pocket” is proposed for a faunule that contains the same genera and species as the older, more extensive parent fauna, and differs only in being reduced spatially. The term “secondary relict pocket” is proposed for a faunule that contains relict genera that were once widespread but have persisted and speciated within the boundaries of the pocket. Based on the faunas of the Caribbean relict pockets, on patterns seen in the fossil record, and on the unusual ecological conditions of the Gulf of Venezuela area, a new reconstruction of Neogene Caribbean molluscan provinciality is proposed and two new Neogene molluscan provinces, the Caloosahatchian and the Gatunian, are described. To explain the existence of the Caribbean relict pockets and their affinities to the Recent Panamic and Neogene Floridian faunas, a new interpretation of Upper Pliocene biological catastrophism and extinction is proposed, incorporating aspects of the effects of the closing of the Isthmus of Panama and glacially-induced sea level fluctuations and temperature changes. A new scheme of Recent tropical American marine molluscan provinciality is presented, taking into account the two paleoprovinces and the distribution of the post-Pleistocene Caribbean fauna.

Influence of the Acoustical Shielding Effect of the Body in Hearing Aid Users

Speech audiometry with two hearing aids of the pocket type was carried out in persons with normal and with impaired hearing. The signal loudspeaker was placed 45° to the left and the louderspeaker giving USASI noise of 55 dB SPL was 45° to the right. With hearing aids placed on the right and left side of the chest the discrimination was significant better than when both hearing aids were located close to each other in front of the chest. In the normally hearing persons the difference at 50% discrimination score was 5.8 dB, in the hearing-impaired persons 4.9 dB. It is probably not a good solution to put two hearing aids together so that they form a single unit because this does not permit the patient to benefit from the acoustical shielding effect of the body.

Some late Pleistocene involutions at Dalton‐in‐Furness, northern England

AbstractInvolutions are reported for the first time from northwest England. They occur in ‘head’ deposits of reworked mudstone, shale, sandstone and breccia soliflucted over glacio‐fluvial sands and gravels in the Poaka Beck valley. The involutions were developed in the late Devensian period and most present a strongly festooned cross‐section. Excavation of these features showed that the regular form was a result of chance sectioning and that the cryoturbate structures were a cellular or pocket type of feature. Frost heave, ice segregation and a reversed density stratification all probably contributed to the development of the involutions, but an important factor was the ground water hydrology which gave especially favourable conditions for strong cryergic activity at this site.

Statistical mechanics of noncovalent bonds in polyamino acids. IV. Matrix treatment of hydrophobic bonds in the random coil and of the helix–coil transition for chains of arbitrary length

AbstractThe Lifson‐Roig matrix theory of the helix–coil transition in polyglycine is extended to situations where side‐chain interactions (hydrophobic bonds) are present both in the helix and in the random coil, as discussed for short chains in paper II of this series. It is shown that the conditional probabilities of occurrence of any number and size of hydrophobic pockets in the random coil can be adequately described by a 2 × 2 matrix. This is combined with the Lifson‐Roig 3 × 3 matrix to produce a 4 × 4 matrix which represents all possible combinations of any amount and size sequence of α‐helix with random coil containing all possible types of hydrophobic pockets in molecules of any given chain length.

The scales of modern lungfish.

SUMMARY A description is given of the scales of Epiceratodus, Protopterus and Lepidosiren, and the associated soft tissues. In Epiceratodus the scale still shows considerable differentiation, and its parts can be related in some degree to those of the ancestral cosmoid scale. The cosmine layer has disappeared, but the outer calcified layer probably represents the remains of the lacunar layer, and the inner laminated layer may represent the isopedine. In Protopterus and Lepidosiren the scales are much simplified but their structure can still be understood through that of Epiceratodus. Direct, attachments between the posterior part of the scale and a superficial connective tissue layer are present in all, and the incomplete type of pocket in which the scale lies differs only in detail.

Fiftieth Anniversary: Anniversary Issue on Storage Batteries: Nickel‐Cadmium Batteries—Pocket Type

not Available.

Burning of Wood Structures by Leakage Currents

Wood pole or structure fires of leakage-current origin have caused serious wood-member damage and service interruption. These fires often occur at the end of prolonged dry periods. Operating experience indicates surface tree carbonization on crossarms and pocket burninig at the crossarm-pole junction to be the two general types of burn damage. Pocket burning on some properties has been responsible for the larger part of the cases that required wood-member replacement. Laboratory tests conducted on approximately 200 specimens indicate that a coincident occurrence of dry wood and selective wetting of pole and crossarm surfaces by a light rain or fog, wind directed, which leaves a dry wood area in series with the leakage path, can result in a fire of a pocket type. This dry area, being high in resistance in comparision with adjacent series wetted-wood surfaces, results in a voltage concentration across the dry zone. If the dry zone is sufficiently short for a given circuit voltage, electrical breakdown occurs across the dry zone. This electrical breakdown being located favorably in dry wood and encouraged by a breeze may result in a pocket burn. Shunting devices which by-pass leakage currents around dry high resistance areas have proven successful in laboratory tests in eliminating pocket fires within the by passed zone.