Surge Operation Research Articles

Traumatic Event Management in Afghanistan: A Field Report on Combat Applications in Regional Command-South

This article provides information on the use of Traumatic Event Management (TEM) strategies to debrief combat arms personnel whose units sustained traumatic losses in Afghanistan. The specific focus is on the application of Event-Driven Battlemind Psychological Debriefings to combat units. This article offers the first published account of TEM services employed in southern Afghanistan during intensive surge operations in 2009-2010. This article unfolds in three parts: (1) background to the region in which the debriefings occurred; (2) three case examples with a data summary of types of incidents observed; and (3) discussion of observations, lessons learned, and recommendations for training future clinicians to provide effective debriefings to combat arms personnel.

Making Mental Health Aerovac Decisions in Afghanistan: A Field Report

This article focuses on the clinical and administrative decision-making processes involved in medevacing psychiatric patients from Kandahar Airfield, Afghanistan, during major surge operations. This article highlights organizational realities pertaining to the medevac process and offers recommendations for incoming providers to optimize their effectiveness in managing at-risk patients in a combat zone.

Research on Detection Evaluation and Reinforcement Technique of Piled Wharf

Accidents, such as storm surge, typhoon, non-normal impacting and other abnormal operating conditions will all cause damage to the structure of piled wharf. To improve the bearing capacity of structure and extend service life, it is need to detect, evaluate and reinforce the piled wharf. This paper analyzes different reasons and ways of destruction then puts up some detection methods for piled wharf’s different components. The evaluation procedures and steps of piled wharf are also disused and mechanism of various reinforcement methods are researched in the same time. The results of this study can provide reference for the detection, assessment and reinforcement of piled wharf structures.

Zolpidem in Fatigue Management for Surge Operations of Remotely Piloted Aircraft

Zolpidem is a hypnotic medication approved to manage sleep for crewmembers involved in combat operations in the USAF and other services. Previous studies demonstrated the effectiveness of zolpidem under laboratory conditions, but confirmation from the field is needed. We evaluated zolpidem in managing sleep-work cycles for crews of remotely piloted aircraft (RPA) during surge combat operations. There were 3 10-mg tablets of zolpidem dispensed to each of 43 crewmembers tasked to support RPA surge combat operations requiring rapid unscheduled shift changes. All personnel were required to take the drug on a non-flying day to evaluate its individual effect; use of the drug during operations was voluntary. The surge operations were carried out successfully with no flight or ground mishaps. There were 27 crewmembers (63%) who used the medication. Of those, 19 reported that the intervention resulted in good sleep without side effects or morning drowsiness. The other eight subjects reported side effects consisting of drug hangover (N = 4) or poor sleep with frequent awakening (N = 4). There were no reports of abnormal sleep behaviors. Five crewmembers considered the medication essential to duty performance. Zolpidem promoted the safe induction of sleep and was used successful by a majority of the RPA crewmembers. Side effects occurred in some crewmembers even though they had previously tested the drug without side effects. A small subset of the test group heavily relied on medication to successfully manage their sleep-rest cycle.

Experiments and modelling of surge in small centrifugal compressor for automotive engines

In this paper the surge phenomenon in small centrifugal compressors used for turbocharging internal combustion engines is analyzed. The experimental work was focused on the measurement of compressor behaviour within the surge zone by means of a specifically designed facility. The presented model is based on the introduction of a fluid inertia term that accounts for the non quasi steady effects and the use of a compressor map extended to the surge and negative flows zone obtained from experimental tests. The compressor model was implemented in a one-dimensional gas-dynamic model. The comparison of the modelled and measured evolution of instantaneous pressure during deep surge operation shows good agreement. Furthermore, the model is also able to predict the amplitude and frequency of pressure pulses when the compressor operates in surge with different outlet duct lengths.

Surge limit definition in a specific test bench for the characterization of automotive turbochargers

This paper describes an experimental facility for the characterization of automotive turbochargers. This installation is used to determine turbine and compressor maps from turbochargers, in situations that are quite similar to reciprocating internal combustion engine operating conditions. A heavy duty diesel engine equipped with modular joints is used as a flow generator for driving the turbines, while the centrifugal compressors flow is independently fixed. In engine operation, automotive turbochargers frequently run the risk of surging and a concise knowledge of the compressor surge limits is needed so that it can be matched correctly with the engine. In this paper, a mathematical tool has been developed for marking out surge operation points from stable compressor points. The detection principle is based on the frequency domain analysis of the instantaneous variables measured in the centrifugal compressor.

A Comparison between Measured and Computed Flow Fields in a Transonic Compressor Rotor

The flow field within the rotor of a transonic axial compressor has been computed and compared to measurements obtained with an advanced laser velocimeter. The compressor was designed for a total pressure ratio of 1.51 at a relative tip Mach number of 1.4. The comparisons are made at 100 percent design speed (20,260 RPM) with pressure ratios corresponding to peak efficiency, near surge, and wide open discharge operating conditions. The computational procedure iterates between a blade-to-blade calculation and an intrablade through flow calculation. Calculated Mach number contours, surface pressure distributions, and exit total pressure profiles are in agreement with the experimental data demonstrating the usefulness of quasi three-dimensional calculations in compressor design.

Investigation of the surge characteristics of power rectifiers and thyristors in large-area press packages

The effects that packaging has on thermal cycling of large-area rectifiers and thyristors in both steady state and surge operation are investigated. A comparison between theoretical and experimental data on forward drop and temperature rise in surge tests are given. A theoretical study is then presented which shows the effects of package variations on device ratings and the size of thermal excursions. The study shows that significant improvements in both steady state and surge device properties can be achieved through advances in packaging techniques.

An Experimental Study of Surge in Centrifugal Compressors

Results of high-response measurements in a high-pressure-ratio centrifugal compressor during surge operation are presented. The interpretation of the data provides improved understanding of the flow mechanism of surge and the phenomena which apparently trigger surge. The mass flow throughout the compressor was observed to oscillate in synchronism during supposedly “stable” operation. Surge of the test compressor occurred when a flow perturbation, during “stable” operation, exceeded an apparent limit. When the instantaneous value of diffuser-inlet pressure recovery factor, Cp2*–4, reached approximately 0.40–0.45, the diffuser inlet flow was badly deteriorated and surge occurred. However, gross separation of the diffuser inlet boundary layer was not observed before surge commencement. It is concluded that instantaneous operating states must be recognized for competent surge prediction. Further, doing so will probably require analysis of the entire compressor system including piping, vessels, flow resistances, etc.

Effects of Zero Sequence Modeling and Transposition on Switching Surge Overvoltages

Zero-sequence frequency dependent parameters for a transmission line with both ground wires and earth return paths and the effects of nontransposition are modeled on an analog transmission system simulator. The effects of this detailed modeling on the overvoltages experienced by a 200 mile 765 kV transmission system. link are investigated, for a variety of switching surge and fault initiation operations, in terms of the resulting overvoltage probability density distributions.

Switching Surge Operating Duty of Lightning Arresters

After mentioning different methods of testing the ability of an arrester to discharge long-duration switching surges, the artificial line discharge test with applied power frequency voltage is discussed. Oscillograms show that voltage transients during such tests may be influenced by the series gap of the test circuit. Test results agree fairly well with curves obtained from digital computations. Hence it appears justifiable to investigate by digital computations alone how test results are influenced by varying certain test- circuit parameters and the rate of rise of the arrester arc voltage. Computations were made for a 525-kV line and a modem 80 percent arrester. Particular mention is made of the disadvantage that could arise from too high a rate of rise of the arc voltage and of the fact that short lines can, in certain cases, impose a heavier duty on an arrester than longer lines.

Equivalent Tests for Switching Surge Operation Duty of Lightning Arresters

Equivalent Tests for Switching Surge Operation Duty of Lightning Arresters