Pressure transients in a Canadian sewage force main

2004 ◽  
Vol 31 (6) ◽  
pp. 1039-1050 ◽  
Author(s):  
David H Axworthy ◽  
Normand Chabot
Keyword(s):  
Pressure Head ◽  
Field Testing ◽  
Water Hammer ◽  
Friction Model ◽  
Data Logging ◽  
Relief Valve ◽  
Protection Measures ◽  
Pump Station ◽  
Before And After ◽  
Surge Protection

Severe water hammer following pump shutdown was suspected to be the cause of pipe displacement at a pump station in Saguenay, Quebec, because it appeared that insufficient surge protection was installed on the force main. To confirm this assertion and prevent further pipe displacement, data logging of a field test of the sewage pump station undergoing power failure was conducted in combination with the development of a water-hammer computer model for the design of additional surge protection measures. This paper describes the results of field testing, both before and after the installation of additional surge protection, and the calibration of a method of characteristics water-hammer model that accounts for vaporous cavitation and unsteady friction effects within the force main. Good agreement is shown between measured and computed pressure head histories at the pump station and at a vacuum relief valve following loss of power to a pump. To the authors' knowledge, this paper presents one of the first applications of the unsteady friction model referenced in this paper to a real system.Key words: sewage, force main, pump, water hammer, unsteady friction, data logging.

scholarly journals Comparison of Latanoprost/Timolol with Carbonic Anhydrase Inhibitor and Dorzolamide/Timolol with Prostaglandin Analog in the Treatment of Glaucoma

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Kenji Inoue ◽  
Shoichi Soeda ◽  
Goji Tomita
Keyword(s):  
Visual Field ◽  
Fixed Combination ◽  
Open Angle Glaucoma ◽  
Field Testing ◽  
Mean Deviation ◽  
Single Action ◽  
Before And After ◽  
Group 2 ◽  
Concomitant Medications ◽  
Medication Changes

Purpose.We retrospectively reviewed medical records of glaucoma patients to investigate how switching medications may affect intraocular pressure (IOP) management. Three concomitant medications were changed to two medications: one combination drop and one single-action drop. Associated adverse effects were also examined.Subjects and Methods.A total of 112 patients with primary open-angle glaucoma or ocular hypertension were examined. All patients were concomitantly using a prostaglandin (PG) analog, aβ-blocker, and a carbonic anhydrate inhibitor (CAI). Fifty-five patients began using latanoprost (PG analog)/timolol (β-blocker) fixed-combination (LTFC) drops and a CAI (group 1), and 57 patients began using dorzolamide (CAI)/timolol fixed-combination (DTFC) drops and a PG analog (group 2). The IOP was measured every 6 months for 2 years following medication changes. Changes in visual field mean deviation (MD) and medication discontinuations were also examined.Results.There were no significant differences in IOP or MD values before and after medication changes in either group. The proportion of medication discontinuations, uncontrolled IOP, and adverse reactions was similar in both groups.Conclusion.Switching patients from multiple single-action medications to combination medications was not associated with changes in IOP, visual field testing results, or adverse event frequency.

scholarly journals Earth-termination system for onshore wind Turbines.

2020 ◽  
Vol 11 (7-2020) ◽  
pp. 66-72
Author(s):  
Liubov A. Belova ◽  
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Lightning Strike ◽  
Lightning Protection ◽  
Protection Measures ◽  
Lightning Strikes ◽  
Grounding System ◽  
Initial Stage ◽  
Wind Turbine Towers ◽  
Surge Protection

The earth-termination system for towers of ground-based wind turbines in addition to protective and functional grounding provides lightning protection grounding, which is especially important since the wind turbine is susceptible to lightning strikes. If insufficient protective measures are taken, the risk of damage to a wind turbine due to a lightning strike increases. Therefore, a well-thought-out built-in grounding system for wind turbine towers is needed, which would function as necessary and guarantee long-term mechanical strength and corrosion resistance. The configuration of grounding systems for wind turbines is discussed in IEC 61400-24, which deals with the topic of lightning protection for wind turbines, including detailed information on the choice of lightning protection measures and surge protection. It is advisable to create a lightning protection concept at the initial stage of planning a wind turbine in order to avoid later costly repairs and retrofitting.

scholarly journals ELIMINATION OF IMPACT WHEN CLOSING THE DISC VALVE ON THE DRAINAGE OF HORIZONTAL SEDIMENTS

2021 ◽  
Vol 11 (1) ◽  
pp. 56-62
Author(s):  
Sergej A. ANCIFEROV ◽  
Elena V. CHIRKOVA ◽  
Mariya N. KUCHERENKO
Keyword(s):  
Numerical Experiment ◽  
Low Pressure ◽  
Water Hammer ◽  
Pneumatic Actuator ◽  
Closed Space ◽  
Additional Energy ◽  
Before And After ◽  
Treatment Facilities ◽  
The Impact

The reasons for the occurrence of an impact when closing a butt erfl y valve installed on pipelines that discharge sludge water from horizontal sedimentation tanks of treatment facilities are considered. The assumption about the possibility of water hammer was experimentally refuted. It is hypothesized that the cause of the impact is the disruption of the fl uid fl ow when fl owing around a fl at plate at critical angles of att ack. A numerical experiment was carried out, which consists in modeling the movement of a water fl ow in a completely fi lled, closed space of a pipe. As a result of the experiment, it was revealed that the fl ow stall was caused by the formation of zones of high and low pressure, respectively, before and after the valve. This provides additional energy to increase the closing torque, comparable to the force of a pneumatic actuator, and results in an impact.

Maximum Pressure Head Due to Linear Valve Closure

1991 ◽  
Vol 113 (4) ◽  
pp. 643-647 ◽  
Author(s):  
Chyr Pyng Liou
Keyword(s):  
Flow Characteristic ◽  
Pressure Head ◽  
Head Loss ◽  
Water Hammer ◽  
Point Of View ◽  
Global Perspective ◽  
Maximum Pressure ◽  
Valve Closure ◽  
Subtle Effect ◽  
Dimensionless Variables

The maximum pressure head resulting from one-speed closure of wide open valves is investigated. The dimensionless variables formulated in this study make the subtle effect of the initial valve head loss explicit and separate from that of the pipe frictional head loss. The maximum head is related to initial pipe frictional head loss, the initial valve head loss, the inherent flow characteristic of the valve, and the closure period by plots of dimensionless variables. The trends of the variation of the maximum pressure head are discussed. An example is used to illustrate the usage of the plots, and to show the advantage of having a global perspective of the phenomenon in the selection and sizing of valves from the water hammer point of view.

Fast Meshless Solution With Lumped Friction for Water Hammer

2020 ◽  
Author(s):  
Yuanzhi Xu ◽  
Zongxia Jiao ◽  
Longfei Zhao
Keyword(s):  
Computational Grid ◽  
Water Hammer ◽  
Friction Model ◽  
Time Cost ◽  
Improved Method ◽  
Fluid Friction ◽  
Time Line ◽  
Practical Applications ◽  
Distributed Friction ◽  
Mesh Grid

Abstract The water hammer in pipelines, with the absence of fluid friction, could be solved by a time-domain exact solution, using a simple recursive process. No computational grid was needed, but the calculation time cost was extremely high. Its improved method, named as the fast meshless solution (FMS), was developed to speed the computation by introducing the time-line interpolation. For the purpose of practical applications, the attempt to consider fluid friction in the FMS is presented here. As there is no mesh grid in the distance-time plane, the distributed friction model can not be employed upon the presented method directly. The fluid friction lumped at the pipe end is proposed, and both steady and unsteady friction are studied. A benchmark problem of the water hammer in a reservoir-pipe-valve (RPV) system is employed for the validation and comparison. The water hammer considering lumped friction can be calculated fast by the FMS, and the accuracy is acceptable. The method discussed here may be of interest in a quick assessment of the piping water hammer.

The Relationship of Lactate to 1-Mile Walk Performance in Women Aged 60 to 70 Years

1998 ◽  
Vol 6 (3) ◽  
pp. 285-289 ◽  
Author(s):  
Carmelo Bazzano ◽  
Lee N. Cunningham ◽  
Giovanni Cama ◽  
Tony Falconio
Keyword(s):  
Older Women ◽  
Blood Lactate ◽  
Field Testing ◽  
Testing Procedure ◽  
Physiological Data ◽  
Walk Test ◽  
Treadmill Test ◽  
Physiological Variables ◽  
Before And After ◽  
The Relationship

The purpose of this study was to examine the relationship between selected physiological variables and lactate accumulation at the end of a l-mile walk test (MWT) in older women (mean ± SD: 64.6 ± 3.1 years). Seventeen women with a peak (ml · kg-1 · min-1) of 21.1 ± 4.2 volunteered to participate. Physiological data were obtained via a COSMED K2 miniaturized O2 analyzer with telemetric capabilities during a maximal treadmill (TM) test and MWT. Blood samples were obtained from the ear lobe for lactale analysis immediately before and after the treadmill test and MWT. Subjects performed the MWT in 15.4 ± 1.4 min at an intensity of 76% of peak and 86% of HRmax. The blood lactate accumulated at the end of the MWT was 2.61 ± 1.47 mmol/L. Peak lactate following the maximal treadmill test was 3.8 ± 1.42 mmol/L. HR during the test was significantly related with blood lactate (r= .65, p< .01). The lactate values observed during the lest suggest that the I-mile walk test is a suitable field testing procedure for older women.

Effects of open field testing and associated handling v. handling alone on the adrenocortical reactivity of piglets around weaning

2002 ◽  
Vol 74 (3) ◽  
pp. 485-491 ◽  
Author(s):  
M. S. Herskin ◽  
K. H. Jensen
Keyword(s):  
Blood Sample ◽  
Open Field ◽  
Field Testing ◽  
Blood Sampling ◽  
Cortisol Response ◽  
Temporal Development ◽  
Novel Object ◽  
Before And After ◽  
Pre Treatment

AbstractEffects of open field testing and associated handling (including blood sampling) v. handling (with blood sampling) alone on adrenocortical reactivity were investigated in piglets around weaning. After weaning at day 28, piglets were mixed to form eight replicates with three litter each and kept on slatted floors. Treatments were open field/novel object testing and associated handling (OFT + H) v. handling alone (H) (no. = 40). Testing took place on the following days (weaning day 0): -4, 0, 1, 4 and 8 (no. = 16). The open field/novel object test lasted 10 min and blood was sampled by venipuncture before and after the test and/or handling procedures. In the first blood sample, plasma concentration of cortisol did not differ between OFT + H and H piglets. In the second blood sample, however, OFT + H piglets had a higher concentration of cortisol and a larger increase in cortisol than H piglets (P < 0·01). In the first blood sample the concentration of cortisol was affected by day (P < 0·05), with concentration on day -4 being lower than those on day 0, 1, and 4 and the concentration on day 8 was lower than the concentration on day 0 as well. However, no differences were found between days for the second blood sample nor the adrenocortical reactivity. In conclusion, the increase in pre-treatment cortisol in the first 4 days after weaning as well as the lack of changes in the adrenocortical reactivity after weaning suggest that the temporal development of HPA activity and reactivity in piglets after weaning are comparable with other, more standardized long-term stressors. Exposure to an open field/novel object test and associated handling results in higher adrenocortical reactivity than handling alone but the latter (including blood sampling) in itself accounts for proportionately 0·74 of the cortisol response.

Validation and Field Testing of an Ergonomic Computer Use Checklist and Guidebook

2002 ◽  
Vol 46 (13) ◽  
pp. 1007-1011 ◽  
Author(s):  
Ira Janowitz ◽  
Arlie Stern ◽  
Don Morelli ◽  
Eileen Vollowitz ◽  
Mark Hudes ◽  
...  
Keyword(s):  
Risk Factors ◽  
Field Test ◽  
Field Testing ◽  
Evaluation Instrument ◽  
Self Assessment ◽  
Self Evaluation ◽  
Working Postures ◽  
Before And After ◽  
Large Employer ◽  
The Subject

The authors developed a validated office ergonomics checklist that focused on outcomes instead of workstation features. The workstation is evaluated primarily through observed working postures and movement patterns while the subject performs their usual tasks. A guidebook for the improvement of computer workstations is keyed to the checklist, to lead the user in reducing risk factors and improving workstation ergonomics. The checklist was first validated in a field test with three expert evaluators. The checklist and guidebook were later tested with a large employer and used as a self-evaluation instrument, by a co-worker, and by an Ergonomics Coordinator with training and experience. Workstations were evaluated by an independent ergonomist before and after interventions were made. Results indicated that the checklist and guidebook were effective in making significant improvements in workstation conditions when administered by an Ergonomics Coordinator, but not when used as a self-assessment or by an untrained co-worker.

scholarly journals Charts for Sizing Surge Anticipating Valve in Rising Mains

2020 ◽  
Vol 9 (7) ◽  
pp. 316-322
Keyword(s):  
Transient Analysis ◽  
Cost Effective ◽  
Water Hammer ◽  
Design Guidelines ◽  
Protection Device ◽  
Analysis Software ◽  
Protection Devices ◽  
Surge Protection ◽  
Selection Of

Transient analysis for large rising mains is performed to protect them from worst effects of water hammer. It requires costly surge analysis software for analysing system for surge & sizing surge protection devices. If software is not available, engineers requires, selection charts or formulae pertaining to quick sizing of surge protection device for given pumping main. If size of surge protection device is known suitable cost shall be considered in budgetary estimates. Surge anticipating valve is a cost effective, compact & reliable surge protection device used in pumping mains. It is installed on delivery manifold of the pump. There are no design guidelines or selection charts available by valve manufacturers for selection of surge anticipating valves. Hence in this paper, charts are prepared to estimate amount of surge & size of surge anticipating valve using KYPIPE TranSurge software after numerous analysis of pumping mains for various combinations of flows, diameters, elevations and lengths. In the end, software results are validated by comparing it with results obtained by experiment.

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