In-situ fluid-pressure measurements for earthquake prediction: An example from a deep well at Hi Vista, California

1985 ◽  
Vol 122 (2-4) ◽  
pp. 255-279 ◽  
Author(s):  
John H. Healy ◽  
T. C. Urban
Keyword(s):  
Earthquake Prediction ◽  
Fluid Pressure ◽  
Pressure Measurements ◽  
Deep Well

Digital manometry to measure cerebrospinal fluid pressure during lumbar puncture

2021 ◽  
pp. 197140092110551
Author(s):  
Robert Heider ◽  
Peter G Kranz ◽  
Erin Hope Weant ◽  
Linda Gray ◽  
Timothy J Amrhein
Keyword(s):  
Cerebrospinal Fluid ◽  
Lumbar Puncture ◽  
Pressure Measurement ◽  
Fluid Pressure ◽  
Cerebrospinal Fluid Pressure ◽  
Pressure Measurements ◽  
Csf Pressure ◽  
Left Lateral Decubitus Position ◽  
Significant Difference ◽  
Time Savings

Rationale and Objectives Accurate cerebrospinal fluid (CSF) pressure measurements are critical for diagnosis and treatment of pathologic processes involving the central nervous system. Measuring opening CSF pressure using an analog device takes several minutes, which can be burdensome in a busy practice. The purpose of this study was to compare accuracy of a digital pressure measurement device with analog manometry, the reference gold standard. Secondary purpose included an assessment of possible time savings. Materials and Methods This study was a retrospective, cross-sectional investigation of 71 patients who underwent image-guided lumbar puncture (LP) with opening CSF pressure measurement at a single institution from June 2019 to September 2019. Exclusion criteria were examinations without complete data for both the digital and analog measurements or without recorded needle gauge. All included LPs and CSF pressures were measured with the patient in the left lateral decubitus position, legs extended. Acquired data included (1) digital and analog CSF pressures and (2) time required to measure CSF pressure. Results A total of 56 procedures were analyzed in 55 patients. There was no significant difference in mean CSF pressures between devices: 22.5 cm H2O digitally vs 23.1 analog ( p = .7). Use of the digital manometer resulted in a time savings of 6 min (438 s analog vs 78 s digital, p < .001). Conclusion Cerebrospinal fluid pressure measurements obtained with digital manometry demonstrate comparable accuracy to the reference standard of analog manometry, with an average time savings of approximately 6 min per case.

A clinical comparison of subdural screw pressure measurements with ventricular pressure

1983 ◽  
Vol 58 (1) ◽  
pp. 45-50 ◽  
Author(s):  
A. David Mendelow ◽  
John O. Rowan ◽  
Lilian Murray ◽  
Audrey E. Kerr
Keyword(s):  
Head Injury ◽  
Intracranial Pressure ◽  
Severe Head Injury ◽  
Fluid Pressure ◽  
Ventricular Catheter ◽  
Pressure Measurements ◽  
Content Type ◽  
Single Lumen ◽  
Ventricular Fluid Pressure ◽  
Fine Print

✓ Simultaneous recordings of intracranial pressure (ICP) from a single-lumen subdural screw and a ventricular catheter were compared in 10 patients with severe head injury. Forty-one percent of the readings corresponded within the same 10 mm Hg ranges, while 13% of the screw pressure measurements were higher and 46% were lower than the associated ventricular catheter measurements. In 10 other patients, also with severe head injury, pressure measurements obtained with the Leeds-type screw were similarly compared with ventricular fluid pressure. Fifty-eight percent of the dual pressure readings corresponded, while 15% of the screw measurements were higher and 27% were lower than the ventricular fluid pressure, within 10-mm Hg ranges. It is concluded that subdural screws may give unreliable results, particularly by underestimating the occurrence of high ICP.

scholarly journals Isolating In-Situ Grip and Push Force Distribution from Hand-Handle Contact Pressure with an Industrial Electric Nutrunner

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 8120
Author(s):  
Cederick Landry ◽  
Daniel Loewen ◽  
Harish Rao ◽  
Brendan L. Pinto ◽  
Robert Bahensky ◽  
...  
Keyword(s):  
Grip Force ◽  
Pressure Sensors ◽  
Measurement Instrument ◽  
Force Distribution ◽  
Pressure Measurements ◽  
Industrial Workers ◽  
Shoulder Injuries ◽  
Significant Difference ◽  
Measured Pressure

Objectives: Grip force during hand tool operation is the primary contributor to tendon strain and related wrist injuries, whereas push force is a contributor to shoulder injuries. However, both cannot be directly measured using a single measurement instrument. The objective of this research was to develop and test an algorithm to isolate the grip and push force distributions from in-situ hand-handle pressure measurements and to quantify their distributions among industrial workers using an electric nutrunner. Methods: Experienced automobile assembly line workers used an industrial nutrunner to tighten fasteners at various locations and postures. The pressure applied by the hand on the tool handle was measured dynamically using pressure sensors mounted on the handle. An algorithm was developed to compute the push force applied to the handle of an electric pistol-grip nutrunner based on recorded pressure measurements. An optimization problem was solved to find the contribution of each measured pressure to the actual pushing force of the tool. Finally, the grip force was determined from the difference between the measured pressure and the calculated pushing pressure. Results: The grip force and push force were successfully isolated and there was no correlation between the two forces. The computed grip force increased from low to high fastener locations, whereas the push force significantly increased during overhead fastening. A significant difference across the participants’ computed grip forces was observed. The grip force distribution showed that its contribution to total hand force was larger than other definitions in the literature. Conclusions: The developed algorithm can aid in better understanding the risk of injury associated with different tasks through the notion of grip and push force distribution. This was shown to be important as even workers with considerable power tool experience applied significantly more grip and push force than other participants, all of whom successfully completed each task. Moreover, the fact that both forces were uncorrelated shows the need for extracting them independently.

Tilt and Interfacial Fluid Pressure Measurements of a Disk Sliding on a Polymeric Pad

2005 ◽  
Vol 127 (1) ◽  
pp. 198-205 ◽  
Author(s):  
Sum Huan Ng ◽  
Len Borucki ◽  
C. Fred Higgs ◽  
Inho Yoon ◽  
Andre´s Osorno ◽  
...  
Keyword(s):  
Negative Pressure ◽  
Reynolds Equation ◽  
Fluid Pressure ◽  
Leading Edge ◽  
Dominant Factor ◽  
Pressure Measurements ◽  
Capacitive Sensing ◽  
One Dimensional ◽  
Pressure Mapping ◽  
Pressure Region

Previous experimental work has shown that negative fluid pressure does develop at the disk/pad interface during chemical mechanical polishing. However, these studies dealt with one-dimensional measurement and modeling. To better understand the problem, two-dimensional pressure mapping is carried out. In addition, the orientation of the disk is measured with a capacitive sensing technique. Results reveal a large negative pressure region at the disk/pad interface that is skewed toward the leading edge of the disk. The disk is also found to be leaning down toward the leading edge and toward the center of the pad. A mixed-lubrication model based on the Reynolds equation and taking into account the disk orientation angles has been developed. Modeling and experimental results show similar trends, indicating the tilting of the disk as a dominant factor in causing the negative pressure phenomenon.

A simplified method for obtaining cerebrospinal fluid pressure measurements in the dog

1963 ◽  
Vol 18 (4) ◽  
pp. 837-837 ◽  
Author(s):  
Javier Verdura ◽  
Robert J. White ◽  
Henry Kretchmer
Keyword(s):  
Cerebrospinal Fluid ◽  
Continuous Monitoring ◽  
Fluid Pressure ◽  
Cerebrospinal Fluid Pressure ◽  
Cerebrospinal Fluid Leakage ◽  
Pressure Measurements ◽  
Fluid System ◽  
Polyethylene Tube ◽  
Simplified Method ◽  
Direct Inspection

A simplified method for recording the cerebrospinal fluid pressure in the dog is presented. It consists of introducing the polyethylene tube of a Rochester needle into the sub-arachnoid space at the level of the ventral atlanto-occipital joint. The advantages of this technique are: the dura mater is punctured under direct vision; a completely sealed fluid system results which permits direct inspection for cerebrospinal fluid leakage; and the animal may be placed in any anatomical position during the continuous monitoring of cerebrospinal fluid pressure. This method of measuring the cerebrospinal fluid pressure has been utilized in 30 canine experiments and has proven equally effective in recording cerebrospinal fluid pressures in monkeys. Submitted on December 21, 1962

scholarly journals Cerebro?spinal fluid pressure measurements during an�sthesia

Anaesthesia ◽  
1966 ◽  
Vol 21 (2) ◽  
pp. 189-201 ◽  
Author(s):  
D. GORDON McDOWALL ◽  
JOHN BARKER ◽  
W. BRYAN JENNETT
Keyword(s):  
Fluid Pressure ◽  
Spinal Fluid ◽  
Pressure Measurements

scholarly journals Artificial Interference of Stress Field in a Near-Fracture show="" $6#?=""Zone by Water Injection in a Preexisting Crack

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Yongxiang Zheng ◽  
Jianjun Liu ◽  
Bohu Zhang
Keyword(s):  
Oil And Gas ◽  
Fractured Reservoirs ◽  
Water Injection ◽  
Fluid Pressure ◽  
In Situ Stress ◽  
Stress Intervention ◽  
Oil And Gas Resources ◽  
Favorable State ◽  
Artificial Stress

The in situ stress has an important influence on fracture propagation and fault stability in deep formation. However, the development of oil and gas resources can only be determined according to the existing state of in situ stress in most cases. It is passive acceptance of existing in situ stress. Unfortunately, in some cases, the in situ stress conditions are not conducive to resource development. If the in situ stress can be interfered in some ways, the stress can be adjusted to a more favorable state. In order to explore the method of artificial interference, this paper established the calculation method of the in situ stress around the cracks based on fracture mechanics at first and obtained the redistribution law of the in situ stress. Based on the obtained redistribution law, attempts were made to interfere with the surrounding in situ stress by water injection in the preexisting crack. On this basis, the artificial stress intervention was applied. The results show that artificial interference of stress can effectively be achieved by water injection in the fracture. And changing the fluid pressure in the crack is the most effective way. By stress artificial intervention, critical pressure for water channelling in fractured reservoirs, directional propagation of cracks in hydraulic fracturing, and stress adjustment on the structural plane were applied. This study provides guidance for artificial stress intervention in the exploitation of the underground resource.

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