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1
Oshati, Olajide Samuel, Arun J. Valsangkar, and Allison B. Schriver. "Earth pressures exerted on an induced trench cast-in-place double-cell rectangular box culvert." Canadian Geotechnical Journal 49, no. 11 (November 2012): 1267–84. http://dx.doi.org/10.1139/t2012-093.
Повний текст джерелаАнотація:
Earth pressure data from the field instrumentation of a cast-in-place reinforced rectangular box culvert are presented in this paper. The instrumented culvert is a 2.60 m by 3.60 m double-cell reinforced cast-in-place rectangular box buried under 25.10 m of fill constructed using the induced trench installation (ITI) method. The average earth pressure measured across the roof was 0.42 times the overburden pressure, and an average of 0.52 times the overburden pressure was measured at mid-height of the culvert on the sidewalls. Base contact pressure under the rectangular box culvert was also measured, providing field-based data demonstrating increased base pressure resulting from downward drag forces developed along the sidewalls of the box culvert. An average increase of 25% from the measured vertical earth pressures on the roof plus the culvert dead load (DL) pressure was calculated at the culvert base. A model culvert was also tested in a geotechnical centrifuge to obtain data on earth pressures at the top, sides, and base of the culvert. The data from the centrifuge testing were compared with the prototype structure, and the centrifuge test results agreed closely with the measured field prototype pressures, in spite of the fact that full similitude was not attempted in centrifuge testing.
2
Davis, M. J. "Microvascular control of capillary pressure during increases in local arterial and venous pressure." American Journal of Physiology-Heart and Circulatory Physiology 254, no. 4 (April 1, 1988): H772—H784. http://dx.doi.org/10.1152/ajpheart.1988.254.4.h772.
Повний текст джерелаАнотація:
The extent to which capillary hydrostatic pressure might be protected from increases in local arterial and venous pressure was examined in the wing microcirculation of unanesthetized pallid bats (Antrozous pallidus). Arterial inflow and venous outflow pressures to the wing were elevated using a box technique to increase pressure around the body of the animal in steps of 12 mmHg between 0 and +60 mmHg for 3-min periods. During this time, hydrostatic pressure, diameter, and red cell velocity in single microvessels were continuously recorded. All branching orders of arterioles constricted significantly during increases in box pressure (Pb), while capillaries and venules dilated. First-order arteriole and venule pressures increased 1:1 with Pb. Capillary pressures increased by only a fraction of Pb up to +36 mmHg, but at higher Pb, the change in capillary pressure was equivalent to the change in Pb. Calculations of vascular resistance indicate that changes in both pre- and postcapillary resistance in this tissue act to prevent increases in capillary pressure during moderate, but not during large, increases in arterial and venous pressure.
3
Zhang, Yunlong, Xin Feng, Hao Zhou, Peng Zhang, Baosong Ma, Lixin Tan, and Jianfeng Wang. "Pressure characteristics of rectangular box jacking considering box-soil-lubricant interaction." Tunnelling and Underground Space Technology 126 (August 2022): 104569. http://dx.doi.org/10.1016/j.tust.2022.104569.
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4
McGuigan, Benjamin L., and Arun J. Valsangkar. "Centrifuge testing and numerical analysis of box culverts installed in induced trenches." Canadian Geotechnical Journal 47, no. 2 (February 2010): 147–63. http://dx.doi.org/10.1139/t09-085.
Повний текст джерелаАнотація:
Induced trench construction is routinely used for circular conduits, but its application for box culverts is less common. To understand the complex soil–structure interaction issues related to the design of induced trench box culverts, centrifuge tests were performed to measure earth pressures on a model box culvert installed in several induced trench configurations. These tests were modelled with FLAC and good agreement was achieved. A parametric study performed with FLAC identified a preferred compressible zone geometry having a width of 1.2 times the culvert width and a thickness of 0.5 times the culvert height. For this geometry, the earth pressure on the top was 0.28 times the overburden, the lateral earth pressure on the sides was 0.47 times the mid-height overburden, and the contact pressure at the base was 0.73 times the overburden plus the pressure from the dead load of the culvert. The average base contact pressures for the induced trench geometry were 35% lower than those for the corresponding positive projecting case. The induced trench method, therefore, appears to be a viable option for box culverts installed under high embankments.
5
Alam, Miah, Omar Chaallal, and Bertrand Galy. "Soil-Structure Interaction of Flexible Temporary Trench Box: Parametric Studies Using 3D FE Modelling." Modelling and Simulation in Engineering 2021 (September 20, 2021): 1–17. http://dx.doi.org/10.1155/2021/9949976.
Повний текст джерелаАнотація:
This paper presents the results of two parametric finite-element studies that were carried out using the PLAXIS-3D finite element (FE) computer code. The following objectives and corresponding parameters were considered: (i) to evaluate the soil pressure on the steel trench box shield; the parameters studied were related to soil type and material, and the study considered till, dry sand, wet sand, and sensitive clay soil; (ii) to assess the effect of trench box material and geometry on earth pressure; the parameters studied were related to trench box material (steel versus aluminum) as well as geometry (plate thickness and strut diameter). These studies included simulation of two steel (or aluminum) trench box shields stacked upon each other to cover the total 6 m (20 ft) deep trench. A Mohr-Coulomb (MC) constitutive material model was chosen for FE analysis (FEA). The FEA results were compared to empirical apparent earth pressure diagrams for a sensitive clay. Comparisons showed that the parameters related to the soil and the trench box have a significant influence on earth pressures.
6
Liu, Guo Dan, Xin Xin Wang, Xuan Wang, Feng Qi, Gang Wang, and Song Tao Hu. "Large Size Static Pressure Box Airflow Distribution." Advanced Materials Research 756-759 (September 2013): 4433–38. http://dx.doi.org/10.4028/www.scientific.net/amr.756-759.4433.
Повний текст джерелаАнотація:
This paper mainly studies at the different way of ventilation to the influence of air distribution in the large size plenum. The model is a grand theatre stalls. To model the plenum which under the grand theatre stalls,and took out the size of large mutations alone modeling and studying it. the six different way of ventilation: small plenum with four directions supply air; Take a duct with four tuyere on supply air; Single tuyere withside air supply; Tuyere parallel supply air; Single tuyere with air supply under; Take a duct with four draught under supply air have influence of air distribution.And combined with the well of heat insulation in the large size plenum.It can use the standard RNG turbulence model, and the pressure interpolation adopt standard discrete format, the convection item of the momentum equations, k equation, ε equation adopt with second order the format. the pressure speed coupling adopt Simple algorithm. Finally through the FLUENT software were used. It can use the air balance coefficient wich is one evaluation index to analyz Simulation results of the Six air distribution mode . Through the analysis and comparison with a wind that four tuyere air supply under Static pressure boxair supply the best effect, the static pressure air distribution most evenly
7
Smith, Thomas R., and M. Bonner Denton. "A High-Pressure Inductively Coupled Plasma Torch." Applied Spectroscopy 41, no. 4 (May 1987): 654–57. http://dx.doi.org/10.1366/0003702874448607.
Повний текст джерелаАнотація:
An inductively coupled plasma (ICP) torch utilizing an extended coolant tube that tapers down to a small exit orifice designed to increase the pressure within the ICP torch is described. This torch design makes use of the advantages associated with higher torch operating pressures (including improved detection limits, increased sensitivity, and better plasma stability), without requiring major modifications to existing commercially available ICP torch box and matching networks. Detection limits obtained with the use of the new torch design are compared with those obtained from several commonly used torch designs using a commercially available torch box and spectrometer. A two- to sevenfold improvement in detection limits is observed through increasing torch operating pressure from 101.325 KPa (760 Torr, or atmospheric pressure) to 120 KPa (900 Torr).
8
Lee, Kicheol, Joonyoung Kim, and Sang Inn Woo. "Analysis of Horizontal Earth Pressure Acting on Box Culverts through Centrifuge Model Test." Applied Sciences 12, no. 4 (February 14, 2022): 1993. http://dx.doi.org/10.3390/app12041993.
Повний текст джерелаАнотація:
Underground space is being utilized due to the saturation of surface ground. The box culvert, as a representative infrastructure that has moved underground, is installed to protect such fixtures as electricity and gas. Because buried box culverts are necessarily affected by soil, it is important to study the earth pressure according to soil type. Herein, the horizontal earth pressure of the buried box culvert was analyzed. Accordingly, a precisely simulated centrifuge model test was performed. Additionally, the coefficient of earth pressure was analyzed. The results had significant variability because, in the existing theory, the horizontal earth pressure acting on the side of the box culvert was only calculated using the coefficient of earth pressure and the friction angle of the soil. Therefore, a correction factor was deemed necessary for calculating the horizontal earth pressure acting on the side of the box culvert.
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Ni, Weixiang, Jian Zhang, and Sheng Chen. "Optimal Location of Energy Dissipation Box in Long Distance and High Drop Gravitational Water Supply System." Water 13, no. 4 (February 10, 2021): 461. http://dx.doi.org/10.3390/w13040461.
Повний текст джерелаАнотація:
In the long-distance and high-drop gravitational water supply systems, the water level difference between the upstream and downstream is large. Thus, it is necessary to ensure energy dissipation and pressure head reduction to reduce the pipeline pressure head. The energy dissipation box is a new type of energy dissipation and pressure head reduction device, which is widely used in the gravitational flow transition systems. At present, there is still a dearth of systematic knowledge about the performance of energy dissipation boxes. In this paper, a relationship between the location of the energy dissipation box and the pressure head amplitude is established, a theoretical optimal location equation of the energy dissipation box is derived, and numerical simulations using an engineering example are carried out for verification. The protective effects of an energy dissipation box placed at the theoretical optimal location and an upstream location are compared. The results indicate that for the same valve action time, the optimal position allows effectively reducing the total volume of energy dissipation box. The oscillation amplitudes of the water level in the box and the pressure head behind the box are markedly reduced. Under the condition that the water level oscillation of the energy dissipation box is almost the same, the optimal location offers better pressure head reduction protection performance than the upstream location.
10
Zhang, Wei Jing. "Study on the Control Strategy and Algorithm for Head-Box." Applied Mechanics and Materials 738-739 (March 2015): 1086–89. http://dx.doi.org/10.4028/www.scientific.net/amm.738-739.1086.
Повний текст джерелаАнотація:
This paper introduces the work process and mechanism of the head-box, from the experimental point of view, analyzed the relationship between the head-box control parameters. The relationship between the level and the total pressure and the relationship between the fan pressure and total pressure is give. Through various experimental results, the control algorithm and strategy of the head-box is proposed. The practice shows that the total pressure control precision is about 3%.
11
Abuhajar, Osama, Tim Newson, and Hesham El Naggar. "Scaled physical and numerical modelling of static soil pressures on box culverts." Canadian Geotechnical Journal 52, no. 11 (November 2015): 1637–48. http://dx.doi.org/10.1139/cgj-2014-0493.
Повний текст джерелаАнотація:
The response of buried box culverts is a complex soil–structure interaction problem, where the relative stiffness between the soil and structure is a critical factor. In addition, soil arching is an important aspect of the soil–culvert interaction problem. A series of static scaled physical model centrifuge tests were performed to investigate soil–culvert interaction. Two different box culvert thicknesses and Nevada sand specimens with different relative densities were used to explore the interaction between the sand and box culverts under different conditions. The static loading consisted of the self-weight from the soil body. The responses of the box culvert were recorded for all loading conditions. The results were evaluated in terms of bending moment, soil pressure, and soil–culvert interaction factors. Soil pressures were evaluated using different experimental methods, which provided comparable results. The soil pressure observed on the culvert top slab showed parabolic distribution, i.e., higher values at the edges and lower at the centre than the theoretical vertical soil (overburden) pressure. The horizontal soil pressure on the side wall increased with depth. The soil–culvert interaction factors decreased at the centre and increased at the edges of the top slab, as the thickness and relative stiffness of the culvert decreased.
12
Xia, Jun Wu, Guo Tao Dou, Di Wang, and Zhen Hua Lu. "Numerical Modeling of Lateral Earth Pressure Acting on Box Culvert under the Ground Deformation." Applied Mechanics and Materials 577 (July 2014): 1166–69. http://dx.doi.org/10.4028/www.scientific.net/amm.577.1166.
Повний текст джерелаАнотація:
Box culvert affected by mining subsidence is exposed to damage potential in relation to the lateral earth pressure. This study intends to specify and compare different ground deformation by the mining subsidence effect in box culvert. For this purpose, a finite-element software (ANSYS) is used to generate models incorporating the soil and a box culvert. The results shows that the lateral earth pressure of box culvert was related to the way of ground deformation, In addition, the kind of soil also affected the distribution and value of the lateral earth pressure.
13
Joyner, M. J. "Does the pressor response to ischemic exercise improve blood flow to contracting muscles in humans?" Journal of Applied Physiology 71, no. 4 (October 1, 1991): 1496–501. http://dx.doi.org/10.1152/jappl.1991.71.4.1496.
Повний текст джерелаАнотація:
The purpose of this study was to determine in humans 1) the gain for the reflex pressor response that occurs when perfusion pressure to rhythmically contracting muscles is reduced and 2) whether the pressor response improves blood flow to the contracting muscles. Six normal subjects performed light, moderate, and heavy rhythmic forearm contractions (30/min) with the forearm enclosed in a Plexiglas box. Pressure in the box was increased 10 mmHg each minute up to 50 mmHg to reduce transmural pressure in the arterial system of the forearm. Mean arterial pressure (MAP) was measured continuously. During light exercise no reflex increase in MAP occurred until box pressure was 50 mmHg. During moderate and heavy exercise MAP began to increase with only 10- to 20-mmHg increases in box pressure. The slope of this increase was 3.5–3.9 mmHg per 10 mmHg of box pressure (approximately 60% of that in dogs). In a further study on six subjects a deep vein draining the active forearm muscles was cannulated and deep venous O2 saturation measured to assess how a 50-mmHg increase in box pressure and subsequent reflex increase in MAP altered blood flow to the contracting muscles during heavy rhythmic exercise. The increase in box pressure reduced blood flow to contracting forearm muscles by 20–25% and was followed by a 19-mmHg increase in MAP that did not appear to improve perfusion of the active muscles. This finding was unexpected, because studies in dogs suggest that the pressor response to rhythmic exercise with restricted muscle blood flow can improve perfusion of the active muscles.(ABSTRACT TRUNCATED AT 250 WORDS)
14
Xiaodong, Wang, and Liu Ciqun. "Horizontal well pressure analysis in box-bounded reservoirs." Applied Mathematics and Mechanics 19, no. 4 (April 1998): 315–20. http://dx.doi.org/10.1007/bf02457535.
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15
Hamza, Leila H., Quang Dang, Xiao Lu, Ayesha Mian, Sabee Molloi, and Ghassan S. Kassab. "Effect of passive myocardium on the compliance of porcine coronary arteries." American Journal of Physiology-Heart and Circulatory Physiology 285, no. 2 (August 2003): H653—H660. http://dx.doi.org/10.1152/ajpheart.00090.2003.
Повний текст джерелаАнотація:
The objective of this study was to determine the effect of passive myocardium on the coronary arteries under distension and compression. To simulate distension and compression, we placed a diastolic-arrested heart in a Lucite box, where both the intravascular pressure and external (box) pressure were varied independently and expressed as a pressure difference (ΔP = intravascular pressure – box pressure). The ΔP-cross-sectional area relationship of the first several generations of porcine coronary arteries and the ΔP-volume relationship of the coronary arterial tree (vessels >0.5 mm in diameter) were determined using a video densitometric technique in the range of +150 to –150 mmHg. The vasodilated left anterior descending (LAD) coronary artery of six KCl-arrested hearts were perfused with iodine and 3% Cab-O-Sil. The intravascular pressure was varied in a triangular pattern, whereas the absolute cross-sectional area of each vessel and the total arterial volume were calculated using video densitometry under different box pressures (0, 50, 100, and 150 mmHg). In the range of positive ΔP, we found that the compliance of the proximal LAD artery in situ (4.85 ± 3.8 × 10–3 mm2/mmHg) is smaller than that of the same artery in vitro (16.5 ± 6 × 10–3 mm2/mmHg; P = 0.009). Hence, the myocardium restricts the compliance of the epicardial artery under distension. In the negative ΔP range, the LAD artery does not collapse, whereas the same vessel readily collapses when tested in vitro. Hence, we conclude that myocardial tethering prevents collapse of large blood vessel under compression.
16
Li, Xiao Hui, Yi Liang Zhang, and Xue Dong Xu. "Failure Analysis of the Stuffing Box in a Super High Pressure Compressor." Advanced Materials Research 415-417 (December 2011): 2226–30. http://dx.doi.org/10.4028/www.scientific.net/amr.415-417.2226.
Повний текст джерелаАнотація:
In this paper, theoretical and experimental researches were done to find the repeated cracking reason of stuffing box in a super hyper pressure compressor. The mathematical expression of the assembly pressure was deduced in interference fit. From macro and micro perspectives, residual stresses were measured by X-ray diffraction in typical position of stuffing box when the packing box in combination and separation states. Besides, metallography and fracture examinations were carried out. The results showed that the real magnitude of shrink range of the failed stuffing box was only account for 12% of the designed size requirements, however, under this working condition this stress was not sufficient to cause cracking; Unqualified smelting process and tensile stress concentration in tank caused micro crack, which finally results in fracture of the stuffing box under fatigue mode.
17
Davis, M. J. "Control of bat wing capillary pressure and blood flow during reduced perfusion pressure." American Journal of Physiology-Heart and Circulatory Physiology 255, no. 5 (November 1, 1988): H1114—H1129. http://dx.doi.org/10.1152/ajpheart.1988.255.5.h1114.
Повний текст джерелаАнотація:
Regulation of blood flow depends on changes in the sum of arterial (Ra) and venous (Rv) resistances, whereas regulation of capillary pressure (Pc) depends on the ratio of Rv to Ra. If the myogenic response of the arterial system (i.e., delta Ra) is the primary mechanism for controlling pressure and flow when perfusion pressure is lowered, then Pc and total flow should be regulated to the same degree under these conditions. This hypothesis was tested by making direct measurements of Pc and flow in skin and skeletal muscle in the wings of unanesthetized bats. The box method was used to reduce perfusion pressure to the wing. Pressures were measured with a servo-null system; flows were computed from measurements of vascular diameters and red cell velocities using intravital microscopy. All branching orders of arterioles dilated significantly during decreases in box pressure (Pb). For 0 less than Pb less than or equal to -30 mmHg, total flow (1st-order arteriolar flow) remained nearly constant, whereas Pc was "regulated" only approximately 60%. These results cannot be explained by changes in arteriolar resistance alone and suggest that changes in Rv may be important. The possible consequences of flow redistribution, capillary recruitment, and micropressure sampling procedures are discussed in relationship to local regulation of capillary pressure and flow.
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Hall, Trevor J., Paul Jones, Richard G. Silcock, and Piet G. Filet. "Grazing pressure impacts on two Aristida/Bothriochloa native pasture communities of central Queensland." Rangeland Journal 39, no. 3 (2017): 227. http://dx.doi.org/10.1071/rj16126.
Повний текст джерелаАнотація:
Managing native pastures for sustainable and economic production requires a good understanding of grazing effects on pasture dynamics. The Aristida/Bothriochloa pastures of north-eastern Australia are important for cattle production but little data on grazing pressure impacts on pastures are available to guide management decisions of producers, for land management education programs, or for predictive modelling. To address this deficiency, four different continuous grazing intensities were imposed on woodland communities over 7 or 8 years at two sites: a Eucalyptus populnea (poplar box) and a E. melanophloia (silver-leaved ironbark) community. Both sites had replicated paddocks grazed at a low, medium or high grazing pressure by +/− tree killing using herbicide (12 paddocks), and 12 ungrazed (nil grazing pressure) 1-ha plots subjected to the same tree-killing contrasts. Grazed paddock areas were fixed and varied between 3.5 and 21.5 ha. Differential grazing pressures were reset each autumn, by adjusting cattle numbers to consume over the next year the equivalent of 0%, 25%, 50% or 75% of the standing pasture mass available. Pasture grasses suitable as indicators of grazing pressure were identified for both communities. Under low grazing pressure, Themeda triandra (kangaroo grass) was the only desirable grass to show a significant increase in total contribution over time at both sites, although Dichanthium sericeum (Queensland bluegrass) also increased its contribution at the poplar box site. Chloris species increased their contribution as grazing pressure increased. The proportion of less palatable Aristida spp. (wiregrasses) in the pasture was not affected by high grazing pressure, although they increased at low grazing pressure in the poplar box community. There were no consistent changes in native legumes or weedy forb species to any treatment. Increasing grazing pressure had a greater negative effect on pasture mass, ground cover and pasture crown cover area than on changing species composition. Most changes in composition due to grazing pressure were smaller than those associated with variable seasonal rainfall, and were greater in the poplar box community. In above-average rainfall years grazing up to 50% of autumn standing pasture mass had no detrimental effect on composition in treeless poplar box country in the short term. The pastures remained stable or improved in both communities when grazing pressure was set annually to utilise 25% of the standing autumn forage.
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Davis, M. J., and P. J. Sikes. "A rate-sensitive component to the myogenic response is absent from bat wing arterioles." American Journal of Physiology-Heart and Circulatory Physiology 256, no. 1 (January 1, 1989): H32—H40. http://dx.doi.org/10.1152/ajpheart.1989.256.1.h32.
Повний текст джерелаАнотація:
The responses of three sequential branching orders of arterioles in the bat wing to rapid and slow changes in transmural pressure were studied. Arterial and venous pressures to the wing were elevated simultaneously by pressurizing a box containing the body of the animal, while the wing was exposed to atmospheric pressure. Box pressure was elevated from 0 to +48 mmHg at two rates: 24 and 0.6 mmHg/s. During this time, continuous recordings of hydrostatic pressure and diameter were made in single arterioles using intravital microscopic techniques. Second-order arterioles and arcuate arterioles from skin and skeletal muscle constricted in response to elevated transmural pressure but did not show an enhanced response to rapid pressure changes. There was a trend for terminal arterioles to show a transient peak constriction during rapid stretch, but this response was always associated with a biphasic change in arteriolar pressure. These results suggest that the transient arteriolar resistance changes associated with rapid transmural pressure increases in previous experiments may be primarily a result of transient pressure changes in small arterioles. We find no evidence that arterioles in this preparation exhibit a rate-sensitive component to their myogenic response.
20
Hu, Huyi. "Box Dimensions and Topological Pressure for some Expanding Maps." Communications in Mathematical Physics 191, no. 2 (February 1, 1998): 397–407. http://dx.doi.org/10.1007/s002200050272.
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Iommi, Godofredo, and Anibal Velozo. "Pressure, Poincaré series and box dimension of the boundary." Nonlinearity 34, no. 6 (June 1, 2021): 3936–52. http://dx.doi.org/10.1088/1361-6544/abfecf.
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22
Yao, Guo Wen, Liang Zhou, Zhi Xiang Zhou, and Shi Ya Li. "Study on Pressure-Bending Stress Transfer in the Joint of the Steel-Concrete Composite Arch Bridge." Advanced Materials Research 250-253 (May 2011): 2053–56. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.2053.
Повний текст джерелаАнотація:
Effective combination and carry-loading together between steel and concrete play important roles for the steel-concrete composite structure. The steel-concrete composite joint decides the constructing safety and life-cycle performance as the key member for the steel-concrete composite arch bridge. The stress distribution in the steel-concrete composite joint was studied by model test under pressure-bending load. And the stress transfer was probed in the steel box, composite joint and reinforced concrete box. The result shows that the steel and reinforced concrete boxes are under elastic compression in the steel-concrete composite joint. The bearing plate can effectively reduce the stress in concrete and steel boxes. This plate and stiffener can smoothly transfer and scatter the stress from steel box to concrete box. The failure mode is concrete cracking near the interface between steel box and concrete box under large eccentric compression.
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Tang, Jia Dong, Yi Ping Lu, Jia De Han, and Zuo Min Wang. "Research of Flow Field for Irradiation Box of Cable Ultraviolet Cross-Linking." Applied Mechanics and Materials 274 (January 2013): 208–11. http://dx.doi.org/10.4028/www.scientific.net/amm.274.208.
Повний текст джерелаАнотація:
In order to analyze the cooling air velocity and pressure distribution characteristics in a ventilation scheme presented for the irradiation box of cable ultraviolet cross-linking, the three-dimensional solid model of the irradiation box was established, its flow field was simulated by software FLUENT according to computational fluid dynamics principle under some calculation conditions. The results show that the air velocity around the cable is higher, enhancing convective heat transfer effect, the irradiation box large space is under negative pressure condition.
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Shan, Renliang, Weijun Liu, Zhe Liu, and Zhien Wang. "Structure Design and Flow Field Analysis of a Model Test Box Used to Study Freezing Temperature Field of Seepage Stratum." Advances in Materials Science and Engineering 2021 (June 17, 2021): 1–11. http://dx.doi.org/10.1155/2021/5587148.
Повний текст джерелаАнотація:
To meet the research needs of the freezing temperature field under seepage, we investigate and design a seepage-freezing model test box, which can meet the requirements of strength, deformation, dispersed flow, simulated laminar flow, and water sealing performance. Using theoretical analysis and calculation, the pressure design index of the model box was obtained. Based on safety considerations, the model test box was designed with a pressure vessel bearing of 0.05 MPa. The structure of “sink + porous plate” was used inside the box. By flow field analysis, the porous plate can effectively reduce the influence of flow convergence to the orifice on the flow field and achieve the purpose of dispersed-water flow and laminar flow simulation. The composite structure form of “panel + frame beam” was adopted to perform the load-bearing test. Under the pressure of 0.05 MPa, the maximum deformation in the x, y, and z directions was <2.4 mm, and the maximum stress was approximately 248 MPa. The model box could meet the requirements of strength and deformation. Water sealing between the upper cover plate and lower box body was achieved by arranging bolts, iron sheets, and silica gel strips. After testing the processed box, we found that the designed box can fully meet the test requirements. These research results may be used as a reference for the development and design of other seepage-freezing model test boxes.
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Shrier, I., and S. Magder. "Pressure-flow relationships in in vitro model of compartment syndrome." Journal of Applied Physiology 79, no. 1 (July 1, 1995): 214–21. http://dx.doi.org/10.1152/jappl.1995.79.1.214.
Повний текст джерелаАнотація:
Compartment syndrome is a condition in which an increase in intramuscular pressure decreases blood flow to skeletal muscle. According to the Starling resistor (i.e., vascular waterfall) model of blood flow, the decrease in flow could occur through an increase in arterial resistance (Rart) or an increase in the critical closing pressure (Pcrit). To determine which explains the decrease in flow, we pump perfused a canine gastrocnemius muscle placed within an airtight box, controlled box pressures (Pbox) so that flow ranged from 100 to 50%, and measured Pcrit, Rart, arterial compliance, small venular pressure (measured by the double-occlusion technique), and venous pressure. An increase in Pbox limited flow mainly through an increase in Pcrit (75–85%), with only small changes in Rart (15–25%) and no change in arterial compliance. Increases in Pbox also produced a vascular waterfall in the venous circulation, but small venular transmural pressure always remained less than control levels. We conclude that increases in Pbox mostly limit blood flow through increases in Pcrit and that Rart plays a minor role. Transmural pressure across the small venules decreases with increases in intramuscular pressure, which contradicts the currently held belief that compartment syndrome is due to a cycle of swelling-ischemia-swelling.
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Paik, Jeom Kee. "Limit State Design Technology for a Membrane Type Liquid Natural Gas Cargo Containment System Under Sloshing Impacts." Marine Technology and SNAME News 43, no. 03 (July 1, 2006): 126–34. http://dx.doi.org/10.5957/mt1.2006.43.3.126.
Повний текст джерелаАнотація:
The aim of the present paper is to develop limit state design technology for cargo containment system structures of membrane type liquid natural gas (LNG) carriers, with the focus on sloshing impacts. The mechanical properties of plywood material making up the NO96 type LNG cargo containment insulation box structures are obtained from tensile coupon testing undertaken in the present study. The ultimate strength characteristics of the LNG cargo insulation box structure under quasi-static pressure action are investigated using ANSYS computer code. The dynamic failure behavior of the insulation box structure under sloshing impacts is examined using LS-DYNA3D computer code. Some important parameters, such as peak pressure and pressure duration time, which affect dynamic failure behavior, are varied in the LS-DYNA3D computations. The limit state design criteria for the insulation box structures under sloshing impacts are developed. Problem areas to be resolved are discussed.
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Cristelo, Nuno, Carlos Félix, and Joaquim Figueiras. "Experimental behaviour of concrete box culverts — comparison with current codes of practice." Canadian Geotechnical Journal 56, no. 7 (July 2019): 970–82. http://dx.doi.org/10.1139/cgj-2018-0506.
Повний текст джерелаАнотація:
It is now accepted that current expeditious models for determining earth pressures on flexible underground structures under compacted layers do not include several technical nuances of the soil–structure interaction. Thus, these models are not capable of delivering an optimized design. The present paper compares the results from the well-known American Association of State Highway and Transportation Officials (AASHTO) model with two different numerical models — a user-friendly elastic model and a more robust finite element model — and with results retrieved from a full-scale monitoring of a concrete box culvert, 5.5 m high and 3.77 m width, over which a 15 m high embankment was built. This structure was instrumented selectively, over a period of almost 1 year, during which several parameters were recorded, including earth pressures and structural deformation. Results have shown that the two most significant drawbacks associated with the use of the AASHTO model are the inadequate evaluation of vertical pressure on the top slab and the coefficient of earth pressure, which results in a significant overestimation of the lateral pressures and, consequently, in an overall inefficient design of the structure.
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Koopmann, G. H., W. Neise, and K. A. Cunefare. "Fan Casing Noise Radiation." Journal of Vibration and Acoustics 113, no. 1 (January 1, 1991): 37–42. http://dx.doi.org/10.1115/1.2930152.
Повний текст джерелаАнотація:
This paper presents a method for assessing the extent of casing noise radiation of a centrifugal fan relative to the aeroacoustic sources associated with the inlet box of the fan. Central to the method is a boundary element program which is used to compute the acoustic pressures on the surfaces of the fan casing in terms of its surface vibration which in this case was measured experimentally. Data from an earlier experiment was used as the starting point for this study. Available data included sound pressure measurements near and away from the inlet box of the fan and vibration measurements over the casing of the fan. Noise from the outlet duct of the fan was purposely highly attenuated. Computations of sound pressure, intensity, and power indicated that, at the blade passing frequency (300 Hz), the aerodynamic sources generated near the entrance plane of the inlet box of the fan dominate the noise spectrum in the field. On the other hand, at the first subharmonic frequency of the blade tone (150 Hz), the sound power generated from the inlet box and fan casing are within 3 dB of each other. Thus, for effective noise control at this frequency, it would be necessary to include both noise sources in the overall treatment.
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Li, Jing, and Yi Jiang. "Numerical Calculation on the Influence of Missile Exhaust Plume with Mechanical Properties to the Double-Launch Box." Advanced Materials Research 978 (June 2014): 101–5. http://dx.doi.org/10.4028/www.scientific.net/amr.978.101.
Повний текст джерелаАнотація:
The adverse impact of the exhaust plume on the inner wall of the vertical launch box and the former friable lid of the adjacent launch box is a common phenomenon, which causes the deformation or damage of the launch container. By using the three-dimensional unsteady numerical simulation, discrete phase model and multicomponent model, the change of the pressure and temperature with time on many monitoring sites are analyzed. The results show that the pressure and the temperature on the edge of the inner wall significantly rise over time after 0.2s. The pressure on the centerline of the inner wall rises over time after 0.2s but the temperature gradually decreases. The maximum pressure on the former friable lid of the adjacent launch box peaks at 0.54s. The conclusion can be regarded as a theoretical reference for engineering application.
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Li, Dong, Shijie Dai, and Tao Lin. "Evaluation of the Explosion Pressure Parameters in Flameproof Enclosures under the Pressure Piling Condition." Energies 14, no. 23 (December 5, 2021): 8156. http://dx.doi.org/10.3390/en14238156.
Повний текст джерелаАнотація:
Explosion resistance is one of the most important performances for all flameproof enclosures. Pressure piling requires the flameproof enclosures to withstand explosion pressure higher than the design pressure. In order to study the explosion parameters in a flameproof enclosure under pressure piling, two experimental setups were prepared based on the theoretical analysis of the mechanism of pressure piling. One setup simulated the condition that the interior of a flameproof box is isolated by a baffle with a small hole. Another setup simulated the condition that a large number of electrical components were installed inside an explosion-proof box. The experimental result showed that the explosion pressure increased significantly in a very short time under pressure piling. When an explosion occurred in a cavity, the pressure wave of the explosion propagated faster than the flame propagation, and the pressure wave was transmitted to another cavity through a gas channel between the two cavities. This resulted in the pre-pressurization of the combustible gas in another cavity. It was observed that the ignition time in the cavity with an ignition source, is the key factor for pressure piling.
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Lee, Jen-shih, Timothy Fallon, Margaret Hunter, Qiang Ye, and Lian-pin Lee. "Respiratory Effect on the Blood Volume of Pulmonary Capillaries." Journal of Biomechanical Engineering 110, no. 2 (May 1, 1988): 150–54. http://dx.doi.org/10.1115/1.3108420.
Повний текст джерелаАнотація:
We measured the density variations of aortic blood from rabbits ventilated by a positive end inspiratory pressure of 6 mmHg or a negative box pressure of the same magnitude. When calculated from the density variations, the fluctuations in blood volume of the pulmonary capillaries within one cycle as induced by an intermittent positive pressure ventilation were found to be similar to the ones induced by an intermittent negative pressure ventilation. Using these volumetric fluctuations as a means to assess the transpulmonary pressure and the transmural pressure across the pulmonary capillaries, we conclude that the switching of the ventilation method did not alter the cyclic fluctuations of these pressures.
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Wang, Zhiyuan. "Thinking outside the Box: Globalization, Labor Rights, and the Making of Preferential Trade Agreements." International Studies Quarterly 64, no. 2 (February 12, 2020): 343–55. http://dx.doi.org/10.1093/isq/sqaa001.
Повний текст джерелаАнотація:
Abstract States can seemingly defy the dictates of globalization. In practice, although being pressured by their competitors, states rarely engage in the race to the bottom by downgrading labor rights laws that are politically costly to pursue. I argue that states’ resistance is made possible by adopting more viable policy alternatives, i.e., concluding preferential trade agreements (PTAs). PTAs can generate considerable economic gains in a less politically costly way than does reducing legal labor protection. As a result, it is expected that a pair of states is more likely to form a PTA in the face of policy pressure to lower legal labor protection. I also argue that facing such pressure, these states are more likely to include strong labor provisions in PTAs. Finally, in the face of the policy pressure, states may feel that signing a PTA is a bit less urgent when they are able to diminish practical labor protection. Applying structural equivalence technique to a new global labor rights dataset to capture the policy pressure to lower legal labor protection, I find robust evidence in support of these conjectures.
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Tang, Longjiang, Jungang Wang, Huizhong Zhu, Maorong Ge, Aigong Xu, and Harald Schuh. "A Comparative Study on the Solar Radiation Pressure Modeling in GPS Precise Orbit Determination." Remote Sensing 13, no. 17 (August 26, 2021): 3388. http://dx.doi.org/10.3390/rs13173388.
Повний текст джерелаАнотація:
For Global Positioning System (GPS) precise orbit determination (POD), the solar radiation pressure (SRP) is the dominant nongravitational perturbation force. Among the current SRP models, the ECOM and box-wing models are widely used in the International GNSS Service (IGS) community. However, the performance of different models varies over different GPS satellites. In this study, we investigate the performances of different SRP models, including the box-wing and adjustable box-wing as a priori models, and ECOM1 and ECOM2 as parameterization models, in the GPS POD solution from 2017 to 2019. Moreover, we pay special attention to the handling of the shadow factor in the SRP modeling for eclipsing satellites, which is critical to achieve high-precision POD solutions but has not yet been fully investigated. We demonstrate that, as an a priori SRP model, the adjustable box-wing has better performance than the box-wing model by up to 5 mm in the orbit day boundary discontinuity (DBD) statistics, with the largest improvement observed on the BLOCK IIR satellites using the ECOM1 as a parameterization SRP model. The box-wing model shows an insignificant orbit improvement serving as the a priori SRP model. For the eclipsing satellites, the three-dimensional (3D) root mean square (RMS) values of orbit DBD are improved when the shadow factor is applied only in the D direction (pointing toward to Sun) than that in the three directions (D, Y, and B) in the satellite frame. Different SRP models have comparable performance in terms of the Earth rotation parameter (ERP) agreement with the IERS EOP 14C04 product, whereas the magnitude of the length of day (LoD) annual signal is reduced when the shadow factor is applied in the D direction than in the three directions. This study clarifies how the shadow factor should be applied in the GPS POD solution and demonstrates that the a priori adjustable box-wing model combined with ECOM1 is more suitable for high-precision GPS POD solutions, which is useful for the further GNSS data analysis.
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Gorecki, J., and W. Byers Brown. "Padded-box model for the effect of pressure on helium." Journal of Physics B: Atomic, Molecular and Optical Physics 21, no. 3 (February 14, 1988): 403–10. http://dx.doi.org/10.1088/0953-4075/21/3/009.
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Titze, Jens. "Interstitial fluid homeostasis and pressure: news from the black box." Kidney International 84, no. 5 (November 2013): 869–71. http://dx.doi.org/10.1038/ki.2013.287.
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Ricciardelli, Francesco, and Horia Hangan. "Pressure distribution and aerodynamic forces on stationary box bridge sections." Wind and Structures 4, no. 5 (October 25, 2001): 399–412. http://dx.doi.org/10.12989/was.2001.4.5.399.
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Shevchenko, Serhii S. "Physical Model and Calculation of Face Packing Seals." Journal of Mechanical Engineering 23, no. 4 (December 30, 2020): 45–51. http://dx.doi.org/10.15407/pmach2020.04.045.
Повний текст джерелаАнотація:
Increasing the reliability and service life of dynamic-pump shaft seals is the most important requirement for their creation. The most common type of seals is still traditional stuffing box seals, which are controlled leakage assemblies that are periodically restored during operation. A radical change in the design of standard stuffing box seals is the transition to face packing seals with a constant pressure against the packing. It is shown that face packing seals can successfully combine the advantages of mechanical face seals and the simplicity and relatively low cost of traditional stuffing box seals. Mechanical face seals, in which one of the packing rings is replaced by a stuffing box packing, have advantages that significantly expand the application of traditional stuffing box seals. A scheme and a physical model of the face packing seal operation are described. During the operation of the seal, the packing is pushed away from the mating metal surface by the pressure of the medium. In this case, a confusor gap is formed, the length of which is proportional to the ratio of the sealed pressure to the pre-compression pressure of the packing. The calculation of the distribution of the hydrostatic pressure and gap along the radius of the face joint of the seal is presented. The irregularity of the contact pressure along the radius, caused by the pressing out of the packing by the sealed inlet pressure, causes premature wear of the overloaded areas of contact surfaces. Expressions are proposed for estimating friction power losses in face packing seals. It is shown that these losses are significantly lower in comparison with the power losses in traditional stuffing box seals. Assessment of the thermal state of face packing seals has been carried out. An expression has been obtained for determining the flow rate that provides the average contact-surface temperature not exceeding the permissible value. Our studies have shown that the load factor of face packing seals, in contrast to mechanical face seals, must be close to unity. The obtained dependencies make it possible to calculate face packing seals at their design stage.
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Ströbele, Markus, and Hans-Jürgen Meyer. "Pandora's box of binary tungsten iodides." Dalton Transactions 48, no. 5 (2019): 1547–61. http://dx.doi.org/10.1039/c8dt04004d.
Повний текст джерелаАнотація:
More than 20 binary tungsten iodides have been discovered. This was possible due to a new synthesis of W3I12 through halide exchange reaction and by thermal scanning. Depending on the I2 partial pressure compounds can incorporate or release I2. On heating they undergo self-reduction. Some tungsten iodide clusters can be directly transferred into solution.
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Kitiyakara, Taya, Patarapong Kamalaporn, Akharawit Poolsombat, Patthama Anumas, Thanyaluck T. Tawarate, and Kesrada Akkanit. "Leak-Testing of an Endoscopic Aerosol Box for Preventing SARS-CoV-2 Infection during Upper Gastrointestinal Endoscopy." Siriraj Medical Journal 73, no. 10 (October 1, 2021): 702–9. http://dx.doi.org/10.33192/smj.2021.90.
Повний текст джерелаАнотація:
Objective: The SARS-CoV-2 virus has infected many healthcare professionals. Endoscopy is an aerosol-generating procedure and the endoscopy team is at risk of exposure and infection. We describe the leak-testing of an aerosol box that uses a glove-covering for the endoscope.Materials and Methods: An endoscopic aerosol box with a glove-covering over the endoscope was made for gastroscopy, EUS and ERCP procedures and was tested for leakage of aerosol/airborne particles. Fine particulate matter (PM) from burnt incense sticks was used as a model for viral aerosol. The leakage from the box was measured by comparing readings from 2 PM light-scattering sensors, one placed inside the box and the other just outside the glove opening in a sealed container. Negative pressure conditions were also used to see if this had any effect on the leakage.Results: The concentration levels of the particulate matter differed with different negative pressure conditions and movement of the endoscope through the glove. Very little leakage was seen with the endoscope stationary even with no negative pressure, at 2.4%, 0.17% and 0.07% for PM1, PM2.5 and PM10, respectively. The maximum leakage was 14% for PM1, 8.7% for PM2.5 and 2.6% for PM10 in the moving-endoscope condition and no negative pressure. This reduced to 6.2%, 1.3%and 0.37% respectively when suction was applied at full strength (negative pressure of -0.05 bar). Conclusion: The glove covering significantly reduced the passage of particles. The particulate leak was seen most with the smallest particles and reached 14% for PM1 without negative pressure. This reduced to 6.2% with maximum negative pressure using the wall suction.
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Volod’ko, Oleg, Aleksandr Bychenin, and Oleg Chernikov. "PRESSURE ACCUMULATOR DISCHARGE EFFECT ON GEAR SHIFT WITH HYDRAULIC CONTROL BOX." Bulletin Samara State Agricultural Academy 5, no. 3 (July 15, 2020): 25–31. http://dx.doi.org/10.12737/38765.
Повний текст джерелаАнотація:
The purpose of the study is the reduction of the time of hydraulic couplings slipping by optimization of hydraulic accumulator discharge pressure. When operating tractors with hydroshift transmission at loads close to the nomi-nal values, there is a problem of slipping of the friction coupling during gear shift without interruption in torque de-livery. There is a critical scientific problem of reducing the slipping of hydroshift transmission during the operation of major tractors. Theoretical prerequisites for increasing friction force due to the reduction of slipping via the re-duction of gear shift time and influence of oil pressure in the booster of the released drive are justified. Procedure and results of study of gear shift in transmission of tractor «Kirovets» with the use of both standard and constant discharge pressure hydraulic accumulators are given. The process of gear shift was investigated on the new gear-box with standard hydraulic accumulator, on the box with standard hydraulic accumulator worn to the limit provided, and on the new gearbox with constant discharge pressure hydraulic accumulator. It has been established that dur-ing operation of a new transmission with standard hydraulic accumulator the 0.2MPa discharge pressure exceeds the optimal value, which leads to an increase in the duration of the shift from 0.915...0.920 s at a pressure of 0.45...0.46 MPa to 1.395...1.04 s at a pressure of 0.65...0.66 MPa. The installation of a constant discharge pressure hydraulic accumulator on the new transmission reduces the discharge pressure to 0.48...0.49 MPa, which reduces the gear shift process to 1.034...1.040 s, that is only 4.2...6.6% higher than the optimal value. Recommendations are given to optimize the gear shift process in the transmission of the «Kirovets» tractor.
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Trevisanut, Amanda Malel. "Taking on the Box Office." Media International Australia 139, no. 1 (May 2011): 149–57. http://dx.doi.org/10.1177/1329878x1113900119.
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For better or worse, under the intensifying pressure of market rationalisation, audience engagement with content produced by the heavily subsidised Australian film industry has become a pivotal issue. Historically, the success of local productions has been evaluated primarily through recourse to box office statistics. Rather than helping the industry, this article argues that over-reliance on this data can only further threaten the security of future government funding by rendering invisible the non-theatrical audience, and lending weight to the perception that Australian audiences don't consume local content. This article contends that an alternative and more suitable resource needs to be created for industry practitioners. It suggests that, as the industry-specific public institution responsible for the aggregation, interpretation and dissemination of industry-specific data, Screen Australia is the ideal candidate to provide such information.
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Yuan, Zhuo Li, Hao Cai Huang, Yan Ying Ye, and Jian Xing Leng. "Study on the Titanium Film in the Pressure Self-Adaptive Water-Tight Junction Box of Underwater Vehicle." Advanced Materials Research 538-541 (June 2012): 16–22. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.16.
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Water-tight junction box (WJB) is one of key underwater vehicle technologies, which is indispensible in nowadays underwater engineering. Taking the advantage of large deformation range and corrosion resistance characters of the titanium material, this paper utilizes the titanium thin film material to put forward a titanium film pressure adaptive compensator (TFPAC) which solves the pressure problem and improves the reliability of the WJB greatly. The finite element analysis (FEA) software ANSYS is used to analyze the stress and strain condition of the titanium film when the film is suffering the internal pressure in the working condition. The feasibility and reliability of the Pressure Self-adaptive Water-tight Junction Box (PSAWJB) is tested and verified by hyperbaric chamber tests.
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Jiang, Qing, Ye Zhang, Shiyou Yan, and Liangyuan Xu. "Optimal Design of an Angular Box for a Mixed Flow Grain Dryer." Applied Engineering in Agriculture 37, no. 4 (2021): 555–62. http://dx.doi.org/10.13031/aea.14643.
Повний текст джерелаАнотація:
Highlights The drying effect in the drying layer is affected by the status of the flow field. The angular box of the drying oven is optimized to improve the drying effect. The structure of the variable-section angular box significantly reduced unevenness and improved the drying effect. Abstract . Dryers are subject to problems as they are unable to fully and uniformly dry grain. Considering the mixed-flow drying process and improving the drying uniformity, this study conducted a numerical simulation of the hot air temperature field, velocity field, and pressure field with ordinary equal cross-section. The dryer was optimized by a variable-section angular box structure for simulation analysis and experimental verification. The results demonstrated the following: the optimized variable cross-section angular box can improve the uniformity of the overall flow of hot air in the drying box; that is, it diffuses uniformly in the temperature, speed, and pressure field of hot air. A comparative analysis of equal cross-section and variable cross-section angled tubes indicated that the unevenness coefficient of the tubes’ wind field of the same section was reduced from 81.31% to 66.8%, 51.19% to 32.78%, and 56.98% to 42.57%, which significantly reduced unevenness and improved the drying effect. Keywords: Angular box, Flow field distribution uniformity, Grain drying, Numerical simulation.
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Varshni, Y. P. "Scaling Relation For The Energy Levels Of A Hydrogen Atom At High Pressures." Zeitschrift für Naturforschung A 57, no. 12 (December 1, 2002): 915–18. http://dx.doi.org/10.1515/zna-2002-1201.
Повний текст джерелаАнотація:
The effect of high pressure on a hydrogen atom has frequently been simulated by enclosing the atom in an impenetrable spherical box. It is shown that for such a confined hydrogen atom placed at the centre of a spherical box a simple scaling relation exists between the energy and the radius of the confining box for 1s, 2p, 3d, and 4f levels, and another similar relation exists for 2s, 3p, and 4d levels.
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McGuigan, Benjamin L., Olajide Samuel Oshati, Bethanie A. Parker, and Arun J. Valsangkar. "Post-construction performance of induced trench rigid culverts." Canadian Geotechnical Journal 53, no. 11 (November 2016): 1807–21. http://dx.doi.org/10.1139/cgj-2016-0088.
Повний текст джерелаАнотація:
Induced trench construction is commonly used to reduce earth pressures on rigid circular and box culverts. Most of the reported literature pertains to the performance of induced trench culverts during construction and shortly after construction. This paper addresses the post-construction performance of induced trench culverts. First, results of field inspection reports are presented as an indirect assessment of performance of 90 induced trench culverts installed in New Brunswick that have been in service for up to 24 years. Second, earth pressure measurements are presented from three case studies where prototype installations were monitored over periods ranging from 4 to 9 years. The case studies presented include a single circular culvert, a cast-in-place double-cell box culvert, and a twin circular culvert installation. The fill heights above the instrumented structures varied from 19 to 25 m. All the available data from both the field inspections and earth pressure measurements indicate that the culverts installed in induced trenches are performing in a satisfactory manner.
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Daye, RM, ML Huber, and RA Henderson. "Interlocking box jejunostomy: a new technique for enteral feeding." Journal of the American Animal Hospital Association 35, no. 2 (March 1, 1999): 129–34. http://dx.doi.org/10.5326/15473317-35-2-129.
Повний текст джерелаАнотація:
A new jejunostomy tube placement technique is described and compared to traditional methods. The interlocking box technique was compared to a simple purse-string with jejunopexy and an inverting serosal tunnel (Witzel technique) with jejunopexy. Procedures performed in fresh canine cadavers were fluid pressure tested following tube removal. Mean+/-standard deviation (SD) intraluminal pressure necessary to induce leakage at the jejunopexy site of the interlocking box group (87.63+/-40.56 cm H2O) was significantly greater (p less than 0.001) than the simple purse-string (43.17+/-31.69 cm H2O) and serosal tunnel (46.33+/-23.60 cm H2O) groups. Significant differences were not identified between the latter groups. The interlocking box technique resisted leakage following acute removal better than conventional techniques and should be tested clinically.
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Yan, Xingyuan, Chenchen Liu, Guanwen Huang, Qin Zhang, Le Wang, Zhiwei Qin, and Shichao Xie. "A Priori Solar Radiation Pressure Model for BeiDou-3 MEO Satellites." Remote Sensing 11, no. 13 (July 5, 2019): 1605. http://dx.doi.org/10.3390/rs11131605.
Повний текст джерелаАнотація:
Due to the cuboid satellite body of BeiDou-3 satellites, the accuracy of their orbit showed a trend of systematic variation with the sun-satellite-earth angle (ε) using the Extend CODE Orbit Model (ECOM1). Therefore, an a priori cuboid box-wing model (named the cuboid model) is necessary to compensate ECOM1. Considering that the body-dimensions and optical properties of the BeiDou-3 satellites used to construct the box-wing model have not yet been fully released, the adjustable box-wing model (ABW) was used for precise orbit determination (POD). The a priori cuboid box-wing model was directly estimated by the precision radiation accelerations, obtained from ABW POD. When using ECOM1 model, for 14 < β < 40°, a linear systematic variation of D0 related to the elevation of the sun above the orbital plane (β-angle) with a slope of 0.048 nm/s2/°, was found for C30. After adding the cuboid model to assist ECOM1 (named Cuboid + ECOM1), the slope was reduced to 0.005 nm/s2/°, and for C20 satellite, the standard deviation (STD) of D0 was improved, from 1.28 to 0.85 nm/s2 (34%). For satellite laser ranging (SLR) validation, when using the ECOM1 model, the systematic variation with the ε angle was about 14 cm for C20 and C30. After using the Cuboid + ECOM1 model, the variation was significantly reduced to about 5 cm. For C20 and C21, compared with the ECOM1 model, the root mean square (RMS) of the ECOM2 and Cuboid + ECOM1 model was improved by about 0.54 (10.3%) and 0.43 cm (8.7%). For C29 and C30, the RMS of ECOM2 and Cuboid + ECOM1 model was improved for about 0.7 (10.9%) and 1.6 cm (25.6%). Finally, the RMS of the SLR residuals of 4.37 to 4.88 cm was achieved for BeiDou-3 POD.
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Meininger, G. A., and J. E. Faber. "Adrenergic facilitation of myogenic response in skeletal muscle arterioles." American Journal of Physiology-Heart and Circulatory Physiology 260, no. 5 (May 1, 1991): H1424—H1432. http://dx.doi.org/10.1152/ajpheart.1991.260.5.h1424.
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The myogenic response was studied in large skeletal muscle arterioles in the presence of varying degrees of constriction with norepinephrine (NE; 3 x 10(-8) to 1 x 10(-5) M) or potassium chloride (KCl, 40-120 mM). The cremaster muscle of anesthetized rats was exteriorized into a Krebs-filled tissue bath chamber for observation of the microvasculature using a video microscopy system. The body of the rats was enclosed in an airtight Plexiglas box that was pressurized from 0 to +30 mmHg to raise intravascular pressure and elicit the myogenic response. All experiments were performed in acutely denervated muscles with propranolol (1 x 10(-6) M) present to produce beta-receptor blockade. Diameter responses of the first-order arteriole (1A) were measured with a videoimage caliper and intravascular pressure with the servo-null micropipette technique. Under basal conditions, without NE, 1A diameter increased in a passivelike fashion from 122 +/- 5.4 to 130 +/- 5.1 microns as box pressure was elevated from 0 to +30 mmHg, respectively. Addition of NE to the cremaster bath produced a dose-dependent constriction of the 1A (EC50 2 x 10(-7) M). In the presence of this adrenergic tone the 1A exhibited myogenic constriction in response to increases in box pressure. For example, topical application of 3 X 10(-7) M NE caused the 1A to constrict from 122 +/- 5.4 to 70 +/- 5.3 microns. In the presence of this adrenergic tone elevating box pressure from 0 to +30 mmHg caused additional constriction to 55 +/- 6.6 microns.(ABSTRACT TRUNCATED AT 250 WORDS)
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Rizzo, Fabio. "Sensitivity Investigation on the Pressure Coefficients Non-Dimensionalization." Infrastructures 6, no. 4 (April 1, 2021): 53. http://dx.doi.org/10.3390/infrastructures6040053.
Повний текст джерелаАнотація:
The scaling of large structures to investigate their aerodynamics in wind tunnels is a common and robust procedure to estimate important magnitudes, including pressure coefficients. Different aspects can affect the estimation of pressure coefficients; four examples are the non-dimensionalization, blockage, non-stationarity, and non-Gaussianity of the wind tunnel velocity. This paper shows the variability of pressure coefficients due to these four aspects for the case study of a closed box section of a suspended bridge. It was estimated that the pressure coefficients of similar pressure taps vary significantly due to different sets of wind velocity time history used to non-dimensionalize the wind tunnel pressures. In addition, the stationarity of the wind velocity process was not confirmed for all wind velocity sets and the non-Gaussianity of the wind velocity time history was confirmed.
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Lai-Fook, Stephen J., and Yih-Loong Lai. "Airway resistance due to alveolar gas compression measured by barometric plethysmography in mice." Journal of Applied Physiology 98, no. 6 (June 2005): 2204–18. http://dx.doi.org/10.1152/japplphysiol.00869.2004.
Повний текст джерелаАнотація:
We developed a method for measuring airway resistance (Raw) in mice that does not require a measurement of airway flow. An analysis of Raw induced by alveolar gas compression showed the following relationship for an animal breathing spontaneously in a closed box: Raw = AbtVb/[Vt (Ve + 0.5Vt)]. Here Abt is the area under the box pressure-time curve during inspiration or expiration, Vb is box volume, Vt is tidal volume, and Ve is functional residual capacity (FRC). In anesthetized and conscious unrestrained mice, from experiments with both room temperature box air and body temperature humidified box air, the contributions of gas compression to the box pressure amplitude were 15 and 31% of those due to the temperature-humidity difference between box and alveolar gas. We corrected the measured Abt and Vt for temperature-humidity and gas compression effects, respectively, using a sinusoidal analysis. In anesthetized mice, Raw averaged 4.3 cmH2O·ml−1·s, fourfold greater than pulmonary resistance measured by conventional methods. In conscious mice with an assumed FRC equal to that measured in the anesthetized mice, the corrected Raw at room temperature averaged 1.9 cmH2O·ml−1·s. In both conscious mice and anesthetized mice, exposure to aerosolized methacholine with room temperature box air significantly increased Raw by around eightfold. Here we assumed that in the conscious mice both Vt and FRC remained constant. In both conscious and anesthetized mice, body temperature humidified box air reduced the methacholine-induced increase in Raw observed at room temperature. The method using the increase in Abt with bronchoconstriction provides a conservative estimate for the increase in Raw in conscious mice.