Vertical Openings Research Articles

Airflow through large openings

The subject of airflow through large openings includes a large number of different problems, ranging from steady gravitational flows to fluctuating flows due to wind turbulence, and including recirculating flows caused by boundary layer effects in a thermally driven cavity. After a review describing the various physical phenomena, and the existing solutions available in the literature to solve this problem, we present in this paper a general solution to predict airflow through large vertical openings. This solution is able to take into account effects of density gradients and turbulence on gravitational flows, and is compatible with a pressure network description for multizone modelling of airflow in buildings.

FLOW RATES OF GRAIN THROUGH VARIOUS SHAPES OF VERTICAL AND HORIZONTAL ORIHCES

ABSTRACT Flow rates of wheat, corn, sorghum, and soybeans through horizontal and vertical orifices were measured. Orifice sizes ranged ft-om 100 to 400 cm2 with each size consisting of six different shaped orifices. The observed relationships between volume flow rate per unit orifice area and orifice hydraulic diameter for both horizontal and vertical orifices were log-linear for all grains. Coefficients for an empirical equation to predict volume flow rate of grain through various sizes and shapes of horizontal and vertical openings were determined and presented. For the same hydraulic diameter, differences in flow rate per unit orifice area were significant among the six different orifice shapes, and the interaction of orifice shape and hydraulic diameter was also significant for all grain and for both vertical and horizontal orifices. Volume fiow rate per unit orifice area increased as the orifice hydraulic diameter increased for all grains. Volume flow rate of grain through vertical orifices was about 37 to 50% of the flow rate through the same orifices placed horizontally.

FLOW RATES OF GRAIN THROUGH VERTICAL ORIFICES

ABSTRACT Flow rates of wheat, corn, sorghum, and soybeans through circular and square vertical orifices were measured. Orifice sizes ranged from 10.2 to 30.5 cm in diameter or side length with increments of 2.5 cm. Moisture contents of the grain lots ranged from 10.2 to 14.4% (w.b.) for wheat, from 13.2 to 22.4% for com, from 11.6 to 18.0% for sorghum, and was 12.3% for soybeans. The observed relationships between volume flow rate and orifice diameter or side length for all grains were log-linear. For a given size of orifice, the flow rate was higher for sorghum and was lower for wheat and corn at the higher moisture content. Coefficients for an empirical equation to predict volume flow rate of grain through vertical openings were determined and presented.

開放系住居の夏の環境特性 : 町家の冷気積層型の上方開放空間

There are two types of traditional wooden house "Noka" and "Machiya" in Japan, which have many wisdoms to make them cool in hot and humid summer. The purpose of this study is to find out the mechanism and seek the way to apply them to the modern house which has thick insulation. Although the large horizontal openings and cross ventilation are the distinctive thermal features of Noka in rural area together with thick thatched roof, deep eaves and naked earth floor, it is not practical to apply them to the modern house in a city. On the other hand the typical town house Machiya, which is the subject of this study is characterized by its vertical openings. Although the Machiya had been built very closely to each other, facing to the paved street and surrounded by roof tiles under the burning sun, there are also found refreshing soft winds in their living spaces. The authors tried to find out the cause of this attractive mechanisms with careful observations, inquiries and physical measurement. The results are as follows ; *A typical Machiya house has two gardens ; small court yard "Tsubo-niwa" and back yard "Ura-niwa" at the both ends of living spaces. *The living spaces are open to these closed yards which are open to the sky. *Living spaces are shaded to the sun by deep eaves, straw blinds and dense trees in the yard. So the living spaces are dark in the day time. *Common walls between the two houses and store rooms on the upper floor isolate the heat from outside as if they had thik insulation. *Warmed air is removed naturally upward through both yards and "Tori-niwa" which is a passage of high ceiling with the opening at the top. *Cooled air from the naked ground at the yards and crawl space under the floor fill the living space like a pool. *In spite of heated breeze on the roof, its fluctuations induce delicate change of air pressure difference between two yards and brings ever changing swings of cool air in the living spaces. Although the Machiya has no insulation at all, it has the same thermal characteristics as the insulated houses at least in summer. This idea of upward opening gives an important suggestion on natural cooling of insulated houses even in cold region.

Marginal fit of porcelain-fused-to-metal and two types of ceramic crown

The marginal fit of Dicor, Cerestore, and porcelain-fused-to-metal crowns was evaluated. Ten premolars free of caries were prepared for each type of restoration and crowns were made. The vertical marginal openings were measured before cementation, after cementation, and after thermocycling. There were statistically significant differences between all three test conditions in each type of crown, between Dicor and porcelain-fused-to-metal crowns after cementation and after thermocycling, and between Cerestore and porcelain-fused-to-metal crowns after thermocycling. All 30 cemented crowns were then embedded in acrylic resin for serial sections for measurement of absolute marginal openings. Statistically significant differences between Dicor and Cerestore crowns and between Cerestore and porcelain-fused-to-metal crowns were found. It was concluded that marginal openings increased after cementation and after thermocycling, and porcelain-fused-to-metal crowns had significantly better marginal fit than that of Dicor and Cerestore crowns.

Technique for radioactivity measurement in drum package waste by using scattered gamma-rays.

An evaluation method for the radionuclide content in low level drum package waste by using scattered γ-rays has been investigated. Gamma-rays are counted by a detector after passing through a collimator having appropriate vertical and horizontal openings both for the segmented scan and for the average geometrical efficiency being almost independent of the source position. The attenuation of unscattered γ-rays is estimated from the intensity ratio of scattered rays to unscattered ones of the nuclide emitting the highest γ-ray energy in the drum. Satisfactory results were obtained in numerical simulations and basic experiments carried out using test equipment with a pure Ge detector and a rectangular collimator, and sample 200l drums, containing sealed 60Co and 137Cs sources, and having a uniform density of 2.2 g/cm3. The error of the evaluated content, which depended slightly on the activity distribution, was a maximum of about ±30%.

Prediction Of Entrained Mass Flows Through Vertical Openings In A Multiroom Fire Model

CIFI (Circulation dans un Immeuble des Fumdes de l'incendie) is a computer program based on a multi-room zone model. It has been developed at CSTB for the purpose of predicting air and smoke movement in a multi-storey building. In the previous versions of CIFI, the mass flows circulating from room to room through vertical openings were calculated from the differences in vertical pressure fields across these openings, but no estimate of entrainments was made. We introduced recently in CIFI a simple set of criteria in order to decide on the possibility of distributing each flow through a vertical opening between the two gaseous layers located downstream. This results in plumes and entrained flows into these plumes, which were approximately estimated. A description of our approach in given and applied to the interpretation of experiments at NBS.

Drought and the organization of tree-hole mosquito communities.

In southeastern North America (North Florida, USA), the duration, frequency, and timing of drought differentially affect the survivorship of pre-adult tree-hole mosquitoes. Drought affects survivorship both by the direct action of dehydration on developing larvae and pupae and by the indirect modulation of predation. The drought-susceptible species, Toxorhynchites rutilus, Orthopodomyia signifera, and Anopheles barberi co-occur in more permanent holes that are larger, with larger, more vertical openings, lower down in larger trees, and contain darker water with higher conductivity, pH, and tannin-lignin content than the holes occupied by Aedes triseriatus that has drought-resistant eggs and rapid larval development. Ovipositing mosquitoes cue on physical and chemical attributes of tree holes independently of host tree species. These same attributes differ among drought-prone and drought-resistant holes but mosquitoes track these attributes more faithfully than the attributes predict tree-hole stability.

Trawl performance during the barents sea cod and haddock survey: potential sources of gear-related sampling bias

Hydroacoustic instruments were used to determine the operating dimensions of the bottom trawls used by Norwegian research vessels to assess the cod and haddock resources in the Barents Sea, with the goal of identifying gear performance characteristics that might have influenced the sampling efficiency of the gear. The observations revealed several aspects of the geometry and performance of the gear that could have reduced its efficiency at sampling demersal and semidemersal o organisms, particularly small fish. These included excessively high door spreads and wing spreads, and low vertical openings. The influence of the trawl's geometry on its sampling efficiency and selectivity is discussed, referring to other studies on gear performance and fish behaviour.

Steel linings in vertical openings : Ball, G S; Harrower, J W Proc of the 1985 Rapid Excavation and Tunneling Conference, New York, 16–20 June 1985V2, P1131–1142. Publ New York: AIME, 1985

Steel linings in vertical openings : Ball, G S; Harrower, J W Proc of the 1985 Rapid Excavation and Tunneling Conference, New York, 16–20 June 1985V2, P1131–1142. Publ New York: AIME, 1985

The influence of urbanization of sinkhole development in central Pennsylvania

The karsted limestone valleys of central Pennsylvania contain two populations of sinkholes. Solution sinkholes occur in the Champlainian limestone units along the margins of the valleys. Solution sinkholes are permanent parts of the landscape and, although a nuisance to construction, do not present other problems. The second population is the suffosional or soil-piping sinkholes These occur on all carbonate rock units including the Beekmantown and Gatesburg dolomites that comprise the two principal carbonate aquifers in the valley. Suffosional sinkholes are the principal land-use hazard. Suffosional sinkholes are transient phonomena. They occur naturally but are exacerbated by runoff modifications that accompany urbanization Suffosional sinkholes are typically 1.5–2.5 m in diameter depending on soil thickness and soil type. The vertical transport of soil to form the void space and soil arch that are the precursors to sinkhole collapse is through solutionally widened fractures and cross-joints and less often through large vertical openings in the bedrock. The limited solution development on the dolomite bedrock combined with soil thickness, seldom greater than 2 m, limits the size of the sinkholes. All aspects of suffosional sinkhole development are shallow processes: transport, piping, void and arch formation, and subsequent collapse take place usually less than 10 m below the land surface Factors exacerbating sinkhole development include pavement, street, and roof runoff which accelerates soil transport Such seemingly minor activities as replacing high grass and brush with mowed grass is observed to accelerate sinkhole development. Dewatering of the aquifer is not a major factor in this region

Variables affecting measurements of vertical occlusal force.

Previous studies of occlusal force have provided conflicting results. The purpose of these studies was to determine whether the extent of vertical opening, contralateral occlusal support, or head posture influenced vertical occlusal forces during swallowing, simulated chewing, and maximum biting effort. Three samples of subjects with normal vertical facial proportions--one each of children, adolescents, and young adults--were evaluated to determine the effects of changes in small (2.5 vs. 6.0 mm) vertical separation of the first molars. A sample of young adults was used to evaluate changes in large (10-40 mm) vertical openings, and a sample of adolescents was used to investigate the effect of contralateral support and head posture. All between-group comparisons were evaluated using non-parametric statistics. For the small vertical openings, there was significantly more vertical occlusal force at 6.0 than 2.5 mm in children during swallowing and chewing but not during maximum biting effort. In adults, there was significantly more force during swallowing at 6.0 than at 2.5 mm separation, but no differences in chewing or maximum biting. Increasingly large vertical openings resulted in a progressive increase in maximum bite force to a maximum at about 20 mm, followed by a decrease and then a second increase to near-maximum force at about 40 mm for young adults. There were no significant differences in vertical force with or without contralateral support or between flexed, normal, and extended head postures at either of the small openings.

Assessment Of Extent And Degree Of Thermal Damage To Polymeric Materials In The Three Mile Island Unit 2 Reactor Building

This paper describes assumptions and procedures used to perform thermal damage analysis caused by post loss-of-coolant-accident (LOCA) hydrogen deflagration at Three Mile Island Unit 2 Reactor. Examination of available photographic evidence yields data on the extent and range of thermal and burn damage. Thermal damage to susceptible material in accessible regions of the reactor building was distributed in non-uniform patterns. No clear explanation for non-uniformity was found in examined evidence, e.g., burned materials were adjacent to materials that appear similar but were not burned. Because these items were in proximity to vertical openings that extend the height of the reactor building, we assume the unburned materials preferentially absorbed water vapor during periods of high, local steam concentration. A control pendant from the polar crane located in the top of the reactor building sustained asymmetric burn damage of decreasing degree from top to bottom. Evidence suggests the polar-crane pendant side that experienced heaviest damage was exposed to intense radiant energy from a transient fire plume in the reactor containment volume. Simple hydrogen-fire-exposure tests and heat transfer calculations approximate the degree of damage found on inspected materials from the containment building and support for an estimated 8% pre-fire hydrogen.

On Minimization of Intersymbol Interference in Digital Magnetic Recording-Reproduction Systems

Some of the severe limitations in achieving high density magnetic recording with satisfactory data reliability are the increase of intersymbol interference and the decrease of signal-to-noise ratio in the readout system. Fourier transform technique serves a useful tool in establishing a logical relationship between magnetic recording reproduction and communication systems. As a result of which, we are in a position to apply, techniques developed in communication theory for achieving high density reliable magnetic recording. The concept of eye pattern as developed in communication theory, is utilized in this paper for evaluating and minimizing the effect of intersymbol interference. A simulation study has been made by applying the correlative level coding technique to calculate the eye-openings. The vertical eye openings versus normalized data transmission rate to bandwidth ratio of various media velocities, thickness and head-to-media distances together with the condition for minimum distortion have also ...

Aspects of the natural history of the swordtail jawfish,Lonchopisthus micrognathus(Poey) (Pisces: Opistognathidae), in south-western Puerto Rico

Summary The burrow-dwelling jawfish, Lonchopisthus micrognathus, occurs at 12–40 m depths on sandy-mud substrates in back reef areas off southwestern Puerto Rico. Its behaviour is remarkably similar to Opistognathus aurifrons. It feeds on suspended material in the water. The burrow has a primary opening with a vertical tube and smaller accessory openings. A crab, Chasmocarcinus cylindricus, occurs with it. Lonchopisthus micrognathus broods its eggs orally and may spawn the year round. Availability of suitable sediment is not limiting distribution of the species.

The Effects of Equalization, Timing, and Carrier Phase on the Eye Patterns of Class-4 Partial-Response Data Signals

A general expression is derived for the eye pattern boundaries of a multilevel class-4 partial-response (PR) signal after single-sideband amplitude-modulation (SSBAM) transmission with a carrier phase error. From the expression particular results are obtained for the horizontal and vertical eye openings of the signal. Expressions are derived for the tap settings of a linear transversal equalizer using the minimum mean-square error (MMSE) criterion when the class-4 PR signal is distorted by a carrier phase error and sampled with timing error. The values of the tap settings can be used to reduce the carrier and timing phase errors. Finally, an expression for the vertical eye opening of the equalized signal is derived as a function of the carrier phase and the number of stages in the equalizer.

Factors affecting infiltration and recharge in a loess covered basin

Hydrographs of shallow piezometers installed in a basin overlain primarily by loess reveal that water infiltrating and percolating through the loess recharges ground water. Local gravity ground-water flow systems adjacent to some intermittent streams thereby are established. Relief on the water table is at a maximum during late winter or spring but decreases steadily through the summer when dry weather and maximal evapotranspiration minimize recharge. Several factors make the loess more or less susceptible to infiltration and percolation. Among the more important are cultivation practices and type of crop grown. Smooth, heavily worked surfaces (commonly planted in winter wheat) appear to act as a major limitation to infiltration capacity. Soil moisture concomitantly is low beneath such surfaces. Root mats developed beneath grassy surfaces provide optimal conditions for infiltration, and consequently for recharge. Measured infiltration capacities are often influenced by near vertical tubular openings extending to a depth of at least 30 feet in the loess. Tracer studies indicate that when sufficient water is available and when surficial infiltration capacity is sufficiently high to form a zone of positive pressure above these openings, they conduct water ahead of the saturation front. Water moves both downward in the openings and laterally into small rootlet holes in the matrix of the loess. By maximization of surface infiltration capacity it may be possible to utilize the tubular openings to induce groundwater recharge.

Stability of Clay at Vertical Opening

The stability of clay at vertical openings in walls and tunnels has been investigated. Laboratory experiments have shown that a cohesive soil flows through a vertical opening when the total overburden pressure exceeds about six times the undrained shear strength of the soil at the level of the opening. Field data collected from tunnels and pipes constructed in soft clays show that no difficulties have been encountered with soil flowing through openings in the tunnel lining or through the tunnel front when the net overburden pressure has been less than six times the undrained shear strength of the soil. Field data indicate, furthermore, that the force required to push a tunnel shield forward into a cohesive soil corresponds to approximately the sum of the overburden pressure and six times the undrained shear strength of the soil.

On unpublished sections illustrating the superficial geology of the northern districts of Edinburgh and the immediate neighbourhood

The late Mr Blackadder, C.E., appears to have presented two papers on local superficial geology to the Wernerian Society, one of which appears in their memoirs, while the unpublished one contains sections of the superficial deposits on which Edinburgh is built. Many of the sections have since appeared in print; but some of the MSS. ones are interesting, as they shed light on recent investigations on this department of local geology. At Fettes Row clayey sand belts were seamed with vertical belts of coal grains; while nearer Bellevue the brown clayey strata, speckled with traversing lines of minute coal grains, in some places became segregated into a firm rock. Here, too, in an exposure of 8 feet, were found vertical crooked openings in the stratified sand of the nature of veins, and filled with foreign matter. They occurred from a depth of a few inches to that of 10 feet, the deeper ones of 10 feet extending many yards horizontally and in a crooked course. Sometimes four or five of those veins were seen a foot or two apart. The direction of the beds was horizontal or slightly inclined. A section at Ann Street is interesting, when connected with similar superficial beds changed into hard stone near the old City Poor House, described to this Society. The following was the section:—1. Gravel. 2. Gravel to the thickness of 3 feet cemented into a calcareous mass, which gradually thinned away into the general mass of loose gravel. In the interstices betwixt