Hole Entrance Research Articles

Fundamental Study of Acid Copper Through‐Hole Electroplating Process

Through‐hole plating experiments were carried out with a gap cell and with Plexiglas boards. The gap cell provided good simulation of the plated through‐hole system and allowed accurate and nondestructive profile analysis of copper deposits. As the current density and the aspect ratio were increased, the copper distribution inside the hole (gap) became more nonuniform. Plugging of holes was observed at high current levels due to current crowding into the hole entrance where the mass transport rate was high. The experimental findings were confirmed by mathematical models which were developed on the basis of electrochemical engineering principles and were applied to the geometric domain that included both the surface of the board and the through‐hole wall. The limits of present through‐hole plating technology are pointed out and possible means for process improvement are discussed.

Seasonal Variation in Nest Placement of Abert's Towhees

Several meteorological variables are known to influence the heat budgets of nesting birds (e.g., Walsberg and King 1978a, b). Such factors include air temperature, incident radiation, wind, and humidity. If the microclimate of the nest is unfavorable, parent birds may become inattentive, exposing eggs or nestlings to excessive heat or cold. They may then desert the nest and their offspring may die. To improve the probability of nesting successfully, many Old World desert birds place their nests so as to receive morning sunlight (Maclean 1976). Several investigators have demonstrated nonrandom orientation of hole entrances of New World cavity-nesting birds (Ricklefs and Hainsworth 1968, Inouye 1976, Inouye et al. 198 1), but few have tested for the significance of nonrandom placement or variation in placement between seasons of open nests. Maclean (1976) indicated that larks in the Kalahari Desert oriented their nests to receive shade in summer and sun in winter. Balda and Bateman (1970) predicted that Pinyon Jays (Gymnorhinus cyanocephalus) in Arizona may place first nests of the season on the sunny sides of ponderosa pines (Pinus ponderosa), but that they may orient later nests more randomly. They showed that these trees in March were 30C warmer on the south side than on the north side, and that the jays selected nest sites to gain more heat: all jay nests, regardless of season, had a significant southward orientation. I report here a second test of Balda and Bateman's (1970) hypothesis, using data for a bird of hotter climates, the Abert's Towhee (Pipilo aberti). This sedentary species inhabits only desert riparian regions of the southwestern United States, whereas the mobile Pinyon Jay occupies a greater elevational and latitudinal range, though breeding chiefly in foothills and lower mountain ranges. Because nests of the Abert's Towhee are typically exposed to higher spring and summer temperatures than those of the Pinyon Jay, a second test of Balda and Bateman's prediction may demonstrate greater seasonal variation in nest placement. The study was conducted in honey mesquite (Prosopis glandulosa) habitat on the Colorado River Indian Reservation 10 km north of Ehrenberg, Arizona. From January to July 1980, I spent 15 h each week (84 5-h searches) looking for nests on, or near a gridded study plot of 20 ha. Field work terminated in July when no new nests were started.

Disturbances to viscometric flow patterns: Birefringence observations

A visual preliminary investigation has been made of the flow pattern adjacent to piezometric holes of different diameters and also the flow pattern upstream and downstream of a jet exit using a birefringence technique. Perturbations to the main flow pattern are noted near to the piezometer hole entrances. At the jet exit initial curvature just upstream of the exit plane is noted at higher flow rates.

A new attempt to estimate the number of nesting petrel, Oceanodroma leucorhoa leucorhoa, and wildlife of the Daikoku Island, Hokkaido

An ecological survey of Daikoku-jima Island was made July 4-8, 1972. It is a 1, 074, 000 km2 islet (six kilometers round, one hundred meters high) located in eastern Hokkaido about 12 kilometer off Akkeshi Pay (Fig. 1), and has the only known breeding colony of the Leach's Fork-tailed Petrel in Japan. There are several fishermen in the northern tip in summer and two lighthouse keepers in the southern end of the islet. The southwest corner of the island (119. 937 m2, 11% of the total area) is conserved as a seabird breeding sanctuary (ig.3).Thirty-six species of birds and three species of mammals were observed on and around the islet (Table 1). Most of the islet is covered with herbaceous plants(Fig. 5), such as Artemisia montana, Urtica platyphylla, Ligularia hodgsonii, Calamagrostis langsdorffii, Sasa nipponica, Polygonum sachalinense etc., and a poor broad-leaved woods, such as Betula ermanii, Quercus mongolica, Alnus hirsuta and Acer mono are seen here and there (Fig. 4). Forty-one species of plants were recorded in 20 plots (3×3 meter square) (Table 2).The dominant species of bird on the island is the Leach's Fork-tailed Petrel (Fig. 2). They begin to come to the island in mid-April and leave at the end of October every year. The petrel digs a tunnel-shaped nest under the ground and lays one white egg. They use dried herbaceous leaves and stems for nesting materials. Takamatsu (1935) observed in 1933 that the first egg was laid July 9. Chicks were found Aug. 19 and then about 80 days after hatching they had fledged.In this survey only eggs were found in the observed nests.Aug. 11, 1956 Abe and Matsuki observed about two-week old nestlings with blackish-grey feathers in the nests.Petrels' nests can be found everywhere on the islet except woods, cliffs and some kinds of vegetation (Fig. 6-a, b). Random sampling was carried out to check the number of nests in each plant community. The numbers of nests in each plant community (3×3 meter square) were 0 to 47 : 47 nests in Artemisia montana community, 33 in Urtica platyphylla, 17 in Polygonum sachalinense, 16 in Cacalina hastata var. orientalis, 5 in Petasites japonicus var, giganteus and no nest was found in Calamagrostis langsdorffii, Ligularia hodgsonii, Miscanthus sinensis community and woodlands. It was found that the difference of the density depended on the vegetation covering on the ground. Some plants, such as Artemisia montana and Urtica platyphylla have very simple root systems, on the other hand, Sasa nipponica, Calamagrostis langsdorffii etc. have very complex root systems (Fig. 8). It is considered that the petrel is not able to dig a tunnel through the complex root systems.Toothpicks were placed at the entrance of the nest hole to check whether the nest was occupied or not on that time (Fig. 9). Four hundred and thirty-seven toothpicks were used for that purpose. Out of 437 toothpicks, 173 toothpicks were missing, i. e. 264 were found in and around the nests. Out of found 264 toothpicks, 97 toothpicks 37% were left as they were, and the remainders (63% 167 toothpicks) were knocked down. It became clear that about 37% of the nests were not used for breeding.The total number of nests on the islet were estimated from the total areas of each vegetation and the numbers of nests on each sampling plot. It amounts to about 1.70×106 nests on the island (370 of them, 1.70×106 nests were not used for breeding).The petrel could be seldom seen on and around the island during daytime, because they are nocturnal (Fig. 7). Diurnal rhythms of the petrel were observed all night long. Numbers of the petrels were counted every five minutes of each hour using two beams of head-lights.

Stresses Due to a Band of Normal Stress at the Entrance of a Circular Hole

The essential difficulty in this radially symmetric problem arises from the geometry involving intersecting cylindrical and plane boundaries. The problem may be reduced by integral transformation to that of solving numerically a single integral equation.

On the recent Exploration of a Cave at Elbolton, near Thorpe

The Craven Naturalists’ Society, in the ardency of youth, were desirous to add their quota of research into caves. We felt we knew but little, and that some practical investigation would help us, and perhaps be of use to more learned and experienced societies. Some of us, in rambling for fossils in the neighbourhood of Thorpe, heard of the existence of this Cave at Elbolton. It seems to have been often visited by the young farmers in the neighbourhood; they call it “Knavvy Noddle Hole.” Whitaker, in his History of Craven, states that he went into a Cave near Thorpe, called Knave Hole Cave, and that there was a tradition that at one time it was a robbers’ retreat. During Easter-week a few of the members of the Craven Naturalists’ Society made a special visit to Thorpe to find this Cave. Skirting the slopes of the grit moorland of Rylstone, Thorpe, and Burnsall Fells, there are a series of peculiar conical limestone hills, of which Elbolton, near to the hamlet of Thorpe, is one of the most prominent. The entrance of Knave Hole is at the foot of a small scar on the south side of Elbolton, about 100 feet from the summit. The present entrance is a pit-like mouth, and a ladder is required to make the descent in safety; the floor of the first chamber being about 20 feet below the mouth; this chamber is about 30 feet long, and varying from 7 feet to 13 feet in ...