Hydrostatic pressures during normal ventilation in the bullfrog tadpole

1968 ◽  
Vol 46 (6) ◽  
pp. 1169-1174 ◽  
Author(s):  
Norman Gradwell ◽  
Valerie M. Pasztor
Keyword(s):  
Buccal Cavity ◽  
Ventilation System ◽  
Compression Stroke ◽  
Pressure Pump ◽  
Pharyngeal Pressure ◽  
Flow Through ◽  
Gill Cavity ◽  
Valvular Function ◽  
Bullfrog Tadpole ◽  
Normal Ventilation

A detailed description of the water flow through the ventilation system of the bullfrog tadpole has been facilitated by recording the time dependence of normal hydrostatic pressures in the system. The mouth and nasal intakes are discontinuous but a pharyngeal pressure pump to support the buccal pressure pump has been found to assist in maintaining a flow through the gill cavity. The alternate action of these pumps drives water into the gill cavity during almost the entire ventilation cycle and owes its efficiency to the occlusion between the buccal cavity and pharynx during the compression stroke of the pharyngeal pump. The need for a valvular function of the ventral velum has thus been demonstrated as it is the only structure between the buccal cavity and pharynx which can effect such cyclic occlusion.

The function of the ventral velum during gill irrigation in Rana catesbeiana

1970 ◽  
Vol 48 (6) ◽  
pp. 1179-1186 ◽  
Author(s):  
Norman Gradwell
Keyword(s):  
Direct Observation ◽  
Rana Catesbeiana ◽  
Buccal Cavity ◽  
Maximum Volume ◽  
Gill Cavity ◽  
Valvular Function

The direct observation of the ventral velum in normally breathing tadpoles confirms earlier evidence for a valvular function of this structure during inspiration. The ventral velum also acts as a hydrofoil during expiration and as a mucus-secreting surface for the entrapment of suspended food particles.As the volume of water pumped per irrigation cycle is normally less than the maximum volume of the buccal cavity, it is unnecessary for the pharynx also to become filled with inspired water during the sinking of the buccal floor. Therefore the ventral velum's cyclic occlusion of the buccal cavity from the pharynx is no handicap to normal irrigation; on the contrary, it is a prerequisite for the efficiency of the pharyngeal pump.The dorsal velum does not participate in valvular activity, but deflects the respiratory current downward and inward to the gill cavity via gill clefts 2, 3, and 4. Therefore the strong flow pumped into the pharynx by buccal compression is prevented from impinging directly on the ciliated groove behind the dorsal velum and thereby interfering with the transport of food into the esophagus.

Gas Control Technology in Heading Laneway Based on Gas Migration Character

2014 ◽  
Vol 716-717 ◽  
pp. 1481-1485
Author(s):  
Shu Fang Wang ◽  
Ye Ming Zheng ◽  
Jian Cheng Zhang
Keyword(s):  
Ventilation System ◽  
Critical Issue ◽  
Gas Migration ◽  
Dual Mode ◽  
Underground Coal Mine ◽  
Experiment Platform ◽  
Weight Calculation ◽  
Simulation Results ◽  
Fuzzy Control Strategy ◽  
Normal Ventilation

Gas disaster and prevention is the critical issue in heading laneways of underground coal mine. There are two goals needs to meet, one is air quantity requirement and energy conservation during normal ventilation, the other is safety and quickly during gas outburst. Firstly, gas migration character and auxiliary ventilation system placements are described in detail. Since two control goals need to reach, a dual-mode fuzzy control strategy for auxiliary ventilation is established. Besides weight calculation method which harmonizes subjective and objective weight calculation is put forward. After then, a gas discharging experiment platform including PLC controller, converter and heading laneway simulation model is established on the basis of theoretical analysis and simulation results. Finally, experimental results have shown that the system can safely and efficiently fulfill the function both at normal ventilation and gas discharging.

scholarly journals An analysis of moist air energy potential during the process of paper band drying

2006 ◽  
Vol 60 (7-8) ◽  
pp. 188-194 ◽  
Author(s):  
Vladimir Valent ◽  
Milorad Krgovic ◽  
Srecko Nikolic
Keyword(s):  
Relative Humidity ◽  
Air Temperature ◽  
Ventilation System ◽  
Specific Consumption ◽  
Moist Air ◽  
Energy Potential ◽  
Dry Air ◽  
Thermodynamic State ◽  
Flow Through ◽  
Kinetics Of

The energy potential of moist air venting from the dryer of the installation for drying paper bands was analyzed. The thermodynamic state of air is defined by the air temperature at the outlet of the dryer and the dew temperature of the air. For the temperature at the outlet of the dryer (55-85?C) and selected dew temperatures (45-65?C), the specific consumption of dry air was determined. For selected kinetics of paper band drying, 10-35 kgH2O/(m2h), the modification of energy potential of the air as a function of air temperature at the outlet of the dryer and the temperature of dew air was specified. The air flow through the dryer was also correlated with the operation of the ventilation system and recuperation of energy. An analysis of the thermodynamic state of moist air venting from the dryer and the calculation of its energy potential confirmed that increase of the dew temperature of the air decreases its energy potential. With the intensity of vaporization Ivm,isp = 10 kgH2O/(m2h), the decrease is 6%. With Ivm,isp = 35 kgH2O/(m2h), the decrease is much greater and amounts to 21.6%. With increasing dew temperature, the specific consumption of dry air decreases, as well as the relative humidity of the air.

The jaw and hyoidean mechanism of the bullfrog tadpole during aqueous ventilation

1968 ◽  
Vol 46 (5) ◽  
pp. 1041-1052 ◽  
Author(s):  
Norman Gradwell
Keyword(s):  
Electrical Stimulation ◽  
Direct Observation ◽  
Buccal Cavity ◽  
Time Sequence ◽  
Lower Jaw ◽  
New Interpretation ◽  
Bullfrog Tadpole

Bullfrog tadpoles (above ca. 18 C) normally achieve branchial ventilation by the rhythmic pumping of water through the buccal cavity. This is facilitated by a coordination between the mandibular and hyoidean movements. Below 70 cycle/min only the lower jaw is active, but both jaws participate at higher frequencies. The jaw and hyoidean muscles and their time sequence were investigated by direct observation, electrical stimulation, lesion, and electromyography. A consideration of jaw ligaments has led to a new interpretation of the jaw mechanism.

Gill irrigation in Rana catesbeiana. Part II. On the musculoskeletal mechanism

1972 ◽  
Vol 50 (5) ◽  
pp. 501-521 ◽  
Author(s):  
Norman Gradwell
Keyword(s):  
Ambient Temperature ◽  
Rana Catesbeiana ◽  
Irrigation System ◽  
Muscle Fibers ◽  
Gill Cavity ◽  
Initial Depression ◽  
Bullfrog Tadpole ◽  
Narrow Opening

The jaw and hyoidean movements and the activity of certain of the muscles which cause these movements have been correlated with hydrostatic pressures in the irrigation system of the bullfrog tadpole. The jaws are capable of three modes of expression: narrow opening, wide opening, and protrusion. During inspiration the initial depression of the buccal floor is passive; active depression occurs near the end of the inspiration phase.Water flows continuously from the gill cavity and is most effusive at the onset of inspiration. Intermittent variations in the amplitude of irrigation result from natural and experimental irritation of the gill cavity. These variations, or hyperirrigations, are correlated with the activity of special muscle fibers, called fibrillic fibers, in the H1c, H2a, H3a, and B4 muscles. The respective contributions to rhythmic irrigation of the alternating buccal and pharyngeal pumps depend on ambient temperature. An auxiliary branchial force pump behind the gill clefts is powered by the H3a muscle in the soft opercular skin.

scholarly journals Investigation of the Use of Underground Cold in a Tunnel-type Ventilation System

2021 ◽  
Vol 7 (9) ◽  
pp. 166-174
Author(s):  
I. Veliyev ◽  
A. Iskenderova ◽  
B. Aliev ◽  
B. Salmanov
Keyword(s):  
Egg Production ◽  
Ventilation System ◽  
Poultry Production ◽  
Cooling Systems ◽  
Climatic Zones ◽  
Factors Affecting ◽  
Operating Modes ◽  
Positive Results ◽  
Normal Ventilation ◽  
Poultry Farming

The article analyzed the main factors affecting the productivity of birds, indicating the importance of poultry production, and also studied the widespread use of two storage systems in poultry farming. As a result of the conducted analyses, the task was set to study the optimal parameters and operating modes of the installation providing tunnel-type ventilation as a working hypothesis for warm climatic zones. The aim of the study was to increase the reliability of the cooling effect inside the building in tunnel-type ventilation installations. Based on the existing methodology, an experiment was conducted and positive results were obtained. The obtained methods have shown that it is not possible to provide the treated moisture inside the building with normal ventilation. Cooling systems ensure normal humidity. But here the use of an underground cooling channel has a wider range of redundancy. In the experimental version, egg production increased by an average of 1.26%, and the weight of eggs increased by 1.5%, and the losses of birds for 5 months of the warm period were 21 heads less.

scholarly journals Determination of the Zone Endangered by Methane Explosion in Goaf with Caving of Longwalls Ventilated on „Y“ System

2016 ◽  
Vol 24 (4) ◽  
pp. 247-251 ◽  
Author(s):  
Jarosław Brodny ◽  
Magdalena Tutak
Keyword(s):  
Oxygen Concentration ◽  
Underground Mining ◽  
Ventilation System ◽  
Hard Coal ◽  
Methane Drainage ◽  
Endogenous Fire ◽  
Flow Through ◽  
Selection Of ◽  
Sufficient Oxygen

Abstract One of the most dangerous and most commonly present risks in hard coal mines is methane hazard. During exploitation by longwall system with caving, methane is emitted to mine heading from the mined coal and coal left in a pile. A large amount of methane also flows from neighboring seams through cracks and fissures formed in rock mass. In a case of accumulation of explosive methane concentration in goaf zone and with appropriate oxygen concentration and occurrence of initials (e.g. spark or endogenous fire), it may come to the explosion of this gas. In the paper there are presented results of numerical analysis of mixture of air and methane streams flow through the real heading system of a mine, characterized by high methane hazard. The aim of the studies was to analyze the ventilation system of considered heading system and determination of braking zones in goaf zone, in which dangerous and explosive concertation of methane can occur with sufficient oxygen concentration equal to at least 12%. Determination of position of these zones is necessary for the selection of appropriate parameters of the ventilation system to ensure safety of the crew. Analysis of the scale of methane hazard allows to select such a ventilation system of exploitation and neighboring headings that ensures chemical composition of mining atmosphere required by regulation, and required efficiency of methane drainage. The obtained results clearly show that numerical methods, combined with the results of tests in real conditions can be successfully used for the analysis of variants of processes related to ventilation of underground mining, and also in the analysis of emergency states.

Annual Analysis of Boundary Conditions on Air Flow through Building Envelope

2016 ◽  
Vol 824 ◽  
pp. 379-386
Author(s):  
Michaela Horáčková
Keyword(s):  
Mechanical Ventilation ◽  
Relative Humidity ◽  
Boundary Conditions ◽  
Ventilation System ◽  
Building Envelope ◽  
Flow Through ◽  
The Difference ◽  
One Year ◽  
Measured Pressure

Leakage in the building envelope may occur airflow as well as its surface. It brings series of adverse consequences, including the flow of diffuse. The airflow building envelope is allowed through a pressure gradient, which is caused by the difference in temperature and wind effects; if necessary a mechanical ventilation system. Article introduces the analysis which was performed on experimental objects of different wind exposition in situ. In this analysis was measured pressure, relative humidity and air temperature in the interior and exterior, for a period of one year. In the conclusion is evaluated the effect of these boundary conditions on the very existence of the airflow through building envelope.

scholarly journals Natural balanced ventilation. Simulations part 2

2018 ◽  
Vol 49 ◽  
pp. 00026
Author(s):  
Tomasz Gaczoł
Keyword(s):  
Natural Ventilation ◽  
Residential Buildings ◽  
Air Flow ◽  
Ventilation System ◽  
Flow Analysis ◽  
Comfort Level ◽  
Test Results ◽  
Pressure System ◽  
Exhaust Duct ◽  
Flow Through

The paper is devoted to test results of air flow through natural ventilation supply-exhaust ducts in the rooms located on the upper floor of the building that were conducted in ANSYS Fluent software. Three types of solutions were selected for the tests: air inflow into the room through the air intake located at the basement level, air inflow through the window ventilator (although no longer used, this solution can be found in many existing residential buildings) and the natural ventilation system supported with the so-called “solar chimney” that is usually a glass superstructure, located on the roof of the building above the ventilation ducts. All simulations were conducted with an outdoor temperature of +3 degrees C. The indoor temperature is + 20 degrees C, considered to be the minimum thermal comfort level. The simulations concerned such issues as: pressure system inside the room and in the exhaust duct, distribution of air temperatures in the room, vector direction of air flow through supply and exhaust ducts and in the room. Tests conducted using a computer method of air flow analysis in ducts and in the analysed room indicate that the developed natural balanced ventilation system is a good solution, especially when building sealing is so common. In all cases presented, it meets the normative regulations and requirements for the ventilation air stream and the air exchange rate in the room. The paper (second part) describes test results concerning the room located on the upper floor of the building, i.e. with a long 9-meter long supply duct and a short 3-meter long exhaust duct.

scholarly journals Heart valve function: a biomechanical perspective

2007 ◽  
Vol 362 (1484) ◽  
pp. 1369-1391 ◽  
Author(s):  
Michael S Sacks ◽  
Ajit P Yoganathan
Keyword(s):  
Heart Valves ◽  
Cardiac Cycle ◽  
Matrix Proteins ◽  
Mechanical Stimuli ◽  
Biological Impact ◽  
Valve Function ◽  
Organ Tissue ◽  
Flow Through ◽  
Cyclic Function ◽  
Valvular Function

Heart valves (HVs) are cardiac structures whose physiological function is to ensure directed blood flow through the heart over the cardiac cycle. While primarily passive structures that are driven by forces exerted by the surrounding blood and heart, this description does not adequately describe their elegant and complex biomechanical function. Moreover, they must replicate their cyclic function over an entire lifetime, with an estimated total functional demand of least 3×10 9 cycles. As in many physiological systems, one can approach HV biomechanics from a multi-length-scale approach, since mechanical stimuli occur and have biological impact at the organ, tissue and cellular scales. The present review focuses on the functional biomechanics of HVs. Specifically, we refer to the unique aspects of valvular function, and how the mechanical and mechanobiological behaviours of the constituent biological materials (e.g. extracellular matrix proteins and cells) achieve this remarkable feat. While we focus on the work from the authors' respective laboratories, the works of most investigators known to the authors have been included whenever appropriate. We conclude with a summary and underscore important future trends.

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