Wright-Patterson Air Force Base Research Articles

Closed-Loop Control Tests for Vertical Fin Buffeting Alleviation Using Strain Actuation

F. Nitzsche¤ Carleton University, Ottawa, Ontario K1S 5B6, Canada D. G. Zimcik† National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada T. G. Ryall‡ Aeronautical and Maritime Research Laboratory, Melbourne, Victoria 3001, Australia R. W. Moses§ NASA Langley Research Center, Hampton, Virginia 23681-2199 and D. A. Henderson¶ U.S. Air Force Research Laboratory, Wright–Patterson Air Force Base, Ohio, 45433-7006

Medical Meteorology: Whether Weather Influences Admissions

To the Editor: Senior residents routinely petition Mother Nature for adverse weather conditions with the hope of reducing their workload by decreasing the number of hospital admissions. To our knowledge, no study to date has challenged the validity of this assumption. Wright-Patterson Medical Center is a US Air Force Regional Medical Center that provides primary and tertiary care to active-duty and retired military members and their dependents. The Wright-Patterson Air Force Base Weather Center is located less than 1 mile from the hospital. All weather data for this study were obtained from this weather center. We collected and compared admission and weather data over 13 noncontinuous months, representing all seasons. We measured the effect of the presence of any rainfall, snowfall, lightning, poor visibility (<5/8 mile), or extreme temperatures (<20°F/>90°F) and weekend/weekday numbers of admissions. For the months studied, the average number of admissions per day to the internal medicine service was 5.9 patients. The univariate analysis of the 6 independent weather variables done with t tests to determine the difference between the presence and absence of the weather variable on admissions is given in Table 1. Admissions were increased when rain was present, and the number was higher on weekdays than on weekends. Admissions were decreased when snow and lightning were present.Table 1Noncontinuous Adverse Conditions and Number of Admissions*Expressed as sample size (mean ± SD number of admissions).ConditionVisibility < 5/8mileRain†P<.01.Snow†P<.01.Lightning†P<.01.Temperature <20°F/>90°FWeekday†P<.01.Present42 (5.92±3.27)66 (6.50±3.40)15 (5.00±2.59)13 (5.00±2.89)23 (5.96±2.92)186 (6.56±1.66)Absent217 (5.91±2.81)193 (5.72±2.58)244 (5.97±2.84)246 (5.96±2.82)236 (5.91±2.82)73 (4.27±2.93)* Expressed as sample size (mean ± SD number of admissions).† P<.01. Open table in a new tab The results of the multiple regression analysis to determine what combinations of variables significantly predict admissions are shown in Table 2. When “weekend” was entered on step 1 with “snowfall” on step 2, the predicted variance was 14.7%. None of the remaining variables entered was significantly predictive. When all variables were forced into the equation, a total of 18.5% of the variance was explained.Table 2Multiple Regression With Admissions per Day as Dependent Variable*Final R2=0.157.R2R changeP valueStep 1: weekend0.1330.133<.001Step 2: snowfall0.1470.014<.001* Final R2=0.157. Open table in a new tab We found that weekends and snowfall together were important predictors of fewer admissions at our institution. While rain and lightning were significant in the univariate analysis, neither entered the prediction equation significantly in the multivariate analysis. The other variables studied did not affect admissions. Our study suggests that adverse weather conditions, with the exception of snowfall, may not reduce the senior resident's admission workload, but an open clinic is likely to increase it. The views expressed in this article are those of the authors and do not reflect the official policy of the Department of Defense or other departments of the US government.

FAILURE OF INTRAOPERATIVE CYSTOSCOPY TO IDENTIFY PARTIAL URETERAL OBSTRUCTION

Division of Urogynecology and Reconstructive Pelvic Surgery, Good Samaritan Hospital, Cincinnati; and the Air Force Institute of Technology, Wright-Patterson Air Force Base, Ohio. The opinions expressed herein are those of the authors and are not necessarily those of the United States Air Force or the Department of Defense. Received January 10, 2000, Received in revised form March 13, 2000, Accepted April 13, 2000

Hip and triaxial compaction of titanium-aluminium-vanadium models: D.P.Delo et al. (Wright-Patterson Air Force Base, Ohio, USA.) Acta Mater., vol 47, no 11, 1999, 3159–3167

Hip and triaxial compaction of titanium-aluminium-vanadium models: D.P.Delo et al. (Wright-Patterson Air Force Base, Ohio, USA.) Acta Mater., vol 47, no 11, 1999, 3159–3167

The Tech Trek - Mobile Research Laboratory Enhances Educational Outreach Efforts at Wright-Patterson Air Force Base, Ohio.

Abstract Wright-Patterson Air Force Base (near Dayton, OH) continues to expand their local community educational outreach programs with the new mobile science research laboratory, Tech Trek - Mobile Research Laboratory. Tech Trek serves surrounding communities using a 40-foot customized Blue Bird bus equipped with an R.J. Lee Instruments Limited portable scanning electron microscope (SEM). The microscope is on loan from the Materials and Manufacturing Directorate of the Air Force Research Laboratory (AFRL) at Wright-Patterson Air Force Base. The purpose of the Tech Trek program is to stimulate school science programs by making state-of-the-art, usually cost-prohibitive scientific equipment and experienced support staff accessible to schools. The program is focussed on providing opportunities for students currently in the grades six through twelve, our future scientists and engineers, to interact with role models in science and technology while being engaged in interesting scientific research. Using this mobile format combination classroom and laboratory,

The Scanning Electron Microscopy Educators Program - A Unique Educational Outreach Program at Wright-Patterson Air Force Base, Ohio.

Abstract Wright-Patterson Air Force Base (near Dayton, OH) continues to offer a unique educational outreach program, Scanning Electron Microscopy EDucatorS (SEMEDS; pronounced sem-eds). This ten year old motivational science program provides an opportunity for students and educators to visit the Materials and Manufacturing Directorate's research laboratories, where scanning electron microscopes (SEMs) are used by scientists and engineers working in diverse areas of materials research. As a favorite motivational science program, SEMEDS serves surrounding communities by bringing students and educators on-site to Wright-Patterson Air Force Base's Air Force Research Laboratory (AFRL) to operate state-of-the-art SEMs in a real life research laboratory setting. The special features of this program include: exposure to a world-class facility, introductions to the elite researchers who work there, and an opportunity for students to operate the same equipment used by the facility researchers. SEMEDS is an after school program intended for middle school and high school students.

Simplified dynamics model of planar two-joint arm movements

A theoretical framework is presented that describes a way in which the inverse dynamics equations of motion of planar two-joint arm movements (EX-model) are reformulated in a simple form. A single point was assumed to define both the wrist and elbow joint centers, and thus the motion of two points in extrinsic space was represented by second-order differential equations to provide the variables in the reformulation (RE-) model. Through an analytical processes, it was shown that the RE-model for reproducing the shoulder joint torque consists of the linearly scaled moment per unit mass responsible for accelerating the wrist and elbow points about the shoulder joint, while that for reproducing the elbow joint torque consists of the linearly scaled moment per unit mass responsible for accelerating the wrist point about the elbow. The scaling factors for variables in the RE-model were based solely on the values for segment lengths, while in the EX-model the inertial parameter data for the segments are involved in its representation. The inertial parameter data of six-arm specimens from the cadaver experiment of Chandler et al. (1975, AMRL Technical Report, Wright-Patterson Air Force Base, OH) were used to develop and verify the numeric solutions of the RE-model. The adequacy of the model varied somewhat among subjects, but minor changes of the physical parameters of the arm segments enabled perfect reformulation, regardless of the specimens. The potential abilities of the RE-model to deal with the complexities in motor control with more simple control schemes are discussed.

Vertebral stress of a cervical spine model under dynamic load

The objective of this study is to develop cervical spine models that predict the stresses in each vertebra by taking account of the biodynamic characteristics of the neck. The loads and the moments at the head point (Occipital Condyle) used for the models were determined by the rigid body dynamic response of the head due to G-z acceleration. The experimental data used were collected from the biodynamic responses of human volunteers during an acceleration in the z direction on the drop tower facility at Armstrong Laboratory at Wright Patterson Air Force Base (WPAFB). Three finite element models were developed: an elastic local model, viscoelastic local model and complete viscoelastic model. I-DEAS software was used to create the solid models, the loadings and the boundary conditions. Then, ABAQUS finite element software was employed to solve the models, and thus the stresses on each vertebral level were determined. Beam elements with different properties were employed to simulate the ligaments, articular facets and muscles. The complete viscoelastic model was subjected to 11 cases of loadings ranging from 8 G-z to 20 G-z accelerations. The von Mises and Maximum Principal stress fields, which are good indicators of bone failure, were calculated for all the cases. The results indicated that the maximum stress in all cases increased as the magnitude of the acceleration increased. The stresses in the 10 to 12 G-z cases were comfortably below the injury threshold level. The majority of the maximum stresses occurred in C6 and C4 regions.

A Comparison of Exhaust Condensation Trail Forecast Algorithms at Low Relative Humidity

Abstract The Schrader and Schumann contrail forecast algorithms and a third algorithm are evaluated under low relative humidity conditions using a dataset of asynoptic atmospheric soundings and 318 coincident ground-based aircraft and contrail observations collected near Dayton, Ohio. Aircraft were positively identified and their flight altitudes were determined using either Federal Aviation Administration flight logs or data collected with the Wright–Patterson Air Force Base air traffic control radar. The sounding data were used with assumed aircraft performance parameters to prepare nowcasts of contrail critical temperatures. The nowcasts were examined subjectively by comparing the distribution of correct and incorrect forecasts as a function of the difference between critical temperature and ambient temperature. Objective evaluation against the contrail observations also was done using several common statistical measures. The third algorithm produced critical temperatures that were systematically too c...

A New Imperial Presidency? Insights from U.S. Involvement in Bosnia

In August 1995, President Bill Clinton caught a lucky break. A few days after Congress voted with veto-proof majorities to lift the arms embargo on Bosnia, the Croatian government launched an offensive against its dissident Serbian minority. Neither the Serb government in Belgrade nor Western nations responded, despite the fact that this Croatian operation was similar to the earlier Serbian cleansing that had received such negative attention in the Western news media. With the clean ethnic borders more or less in place, Serbia and Croatia appeared finally ready to move toward a settlement that had plagued the two countries since the breakup of Yugoslavia in 1991. However, when the Serbs continued to attack Muslim military positions in Sarajevo, Clinton was able to advance his alternative to congressional pressure to lift the arms embargo to the Western allies-namely, air strikes against the Serbs. The air strikes had the dual impact of blunting the efforts to override the vote on lifting the arms embargo and providing the military muscle to bring the warring sides in the Bosnian conflict to the bargaining table. After several weeks of U.S.-sponsored negotiations at Wright-Patterson Air Force Base in Dayton, Ohio, the principals representing the three factions in Bosnia-Croats, Serbs, and Muslims-initialed a peace agreement on 21 November 1995. A few days after the formal signing of the Dayton Peace Accords in Paris on 14 December, President Clinton ordered the deployment of more than 20,000 United States troops as part of a NATO-led Implementation Force (IFOR) of 60,000, which was charged with patrolling and enforcing a cease-fire and a zone of separation between the newly created semiautonomous entities

Air Force Application of Advanced Magnetic Materials

ABSTRACTA national initiative is underway to develop and test a more electric aircraft (MEA) and is being led by the U.S. Air Force Research Laboratory at Wright-Patterson Air Force Base, Ohio. The MEA concept is based on utilizing electric power to drive aircraft subsystems which are currently driven by a combination of hydraulic, pneumatic, electric and mechanical power transfer systems. A major objective of this effort is to increase military aircraft reliability, maintainability and supportability and to drastically reduce the need for ground support equipment. These improvements will be realized through the further advancement of key MEA technologies, including magnetic bearings, aircraft integrated power units (IPU), and starter/generators (IS/G) internal to an aircraft main propulsion engine. These advanced developments, as well as weapon and space power applications, are the driving force for the new emphasis on high temperature and high strength magnetic materials for power applications. In determining the best magnetic material for an application it is typically necessary to conduct an engineering trade-off analysis which takes into consideration mechanical behavior, electrical loss, and magnetic properties under the conditions of actual usage. New materials solutions are required to meet these challenges, as designers often find the magnetic material performance to be the technological limitation.

Use of Ada in digital radar landmass simulation (DRLMS)

2. Introduction Radsim(TM) is a line of cost-effective, high fidelity, multi-mode radar simulations implemented entirely in software. This approach allows Radsim(TM) to easily adapt to a wide variety of training system applications. The latest version consists of SAIC's patented core radar simulation technology, including the fundamental algorithms and processes necessary to produce real-time synthetic aperture radar, doppler beam sharpening and real beam imagery. Implemented as an Ada95 class library that allows the construction of new Radar simulations with a fraction of the work required to build custom simulations. Figure 1 is a Radsim generated 1 meter Synthetic Aperture Radar image of some buildings. Note the highlights and shadows for individual buildings. 3. Initial Work RADSIM(TM) is based on a highly successful approach developed for simulating the AN/APQ-164 radar on the B-1B Engineering Research Simulator built by SAIC for the Armstrong Aerospace Research Laboratory at WrightPatterson Air Force base in 1984. One of the driving requirements of the B-1B DRLMS was a high degree of simulated image fidelity and correlation with real-world radar imagery. This original DRLMS was developed in a combination of PLM and FORTRAN. It was highly successful, but extremely expensive to maintain and tied to SAIC proprietary hardware.

Effects of simulated aircraft noise on the behavior and egg production of white leghorn chickens

White leghorn chicken poults (3 weeks and 8 weeks of age) and laying pullets (48 weeks of age) were exposed to a series of simulated jet aircraft overflights. Poultry were exposed in small groups (∼35 birds/pen) in barns equipped with a U. S. Air Force-designed simulation system. For poult experiments, 72 pens were exposed four to six times per day for 4 days. For experiments with laying hens, 60 pens were exposed four times per day for two 5-day blocks over a 2-week period. Level of exposure ranged from 105 dB ASEL down to the ambient noise floor in the barns. Ambient noise was dominated by poultry vocalizations and fan noise (70–85 dBA). Behavior, food and water consumption, mortality, weights (poults), and laying success (hens) were measured for each pen throughout the experiment. Neither poults nor hens responded to simulated overflights with panic flight, piling, or any other hazardous behavior, regardless of exposure level. However, 8-week-old poults picked at one another more often in the most highly exposed pens. Hens exhibited brief, small decreases in laying rate after initial exposure. Over the experimental period, the decrease was not significant. [Work supported by the U.S. Air Force, AL/OEBN, Wright–Patterson Air Force Base (F41624-95-C-6014 DO-C9).]

Voices in the Museum

Museum visitors hear many voices. artifacts themselves speak with the greatest clarity and authority, carrying the burden of the exhibit. A curatorial voice emerges from labels, story lines, and even the selection of artifacts. museum itself gives voice to its history and purpose. Sometimes voices from the street intrude upon the visitor's experience. All these voices reverberated through the exhibit of the Enola Gay, producing a tower of Babel. National Air and Space Museum (NASM), reportedly the most visited museum in the world, intrudes on the visitor's communion with the artifacts. Perhaps all Smithsonian museums do. The Nation's Attic, as the Smithsonian has been labeled, is a special kind of repository. Unlike many museums, which display all or most of their collection, the Smithsonian displays only a small fraction. Choosing what will be removed from the attic and put on public display necessarily mediates the collection. Putting an artifact in one of the museums on the Mall, the nation's front yard, attaches still more symbolism to the selection. Putting the object in the world's most visited museum, within sight of the halls of Congress, burdens the exhibit still further. NASM would be an ideal place if only it could insulate its exhibits from the symbolism of the place. Few museums suffer this handicap. Normally, the voice of the artifacts dominates that of the repository. Bock's Car, the airplane that dropped the atomic bomb on Nagasaki, has been on display for years at WrightPatterson Air Force Base in Dayton, Ohio. aircraft has stirred no great public controversy, because visitors expect an air force museum to celebrate this instrument of war. It is something else again to display Enola Gay, the Hiroshima bomber, in the NASM on the Mall. site of the exhibit, in the same building with the Wright Flyer, the Spirit of St. Louis, and the Apollo 11 space capsule, trumpets celebration.1 By its own existence, the NASM colors its artifacts.

Use of 3H/3He Ages to evaluate and improve groundwater flow models in a complex buried‐valley aquifer

Combined use of the tritium/helium 3 (3H/3He) dating technique and particle‐tracking analysis can improve flow‐model calibration. As shown at two sites in the Great Miami buried‐valley aquifer in southwestern Ohio, the combined use of 3H/3He age dating and particle tracking led to a lower mean absolute error between measured heads and simulated heads than in the original calibrated models and/or between simulated travel times and 3H/3He ages. Apparent groundwater ages were obtained for water samples collected from 44 wells at two locations where previously constructed finite difference models of groundwater flow were available (Mound Plant and Wright‐Patterson Air Force Base (WPAFB)). The two‐layer Mound Plant model covers 11 km2 within the buried‐valley aquifer. The WPAFB model has three layers and covers 262 km2 within the buried‐valley aquifer and adjacent bedrock uplands. Sampled wells were chosen along flow paths determined from potentiometric maps or particle‐tracking analyses. Water samples were collected at various depths within the aquifer. In the Mound Plant area, samples used for comparison of 3H/3He ages with simulated travel times were from wells completed in the uppermost model layer. Simulated travel times agreed well with 3H/3He ages. The mean absolute error (MAE) was 3.5 years. Agreement in ages at WPAFB decreased with increasing depth in the system. The MAEs were 1.63, 17.2, and 255 years for model layers 1, 2, and 3, respectively. Discrepancies between the simulated travel times and 3H/3He ages were assumed to be due to improper conceptualization or incorrect parameterization of the flow models. Selected conceptual and parameter modifications to the models resulted in improved agreement between 3H/3He ages and simulated travel times and between measured and simulated heads and flows.

A proposed method for allocation of compensation for noise-induced hearing loss

The method proposed uses the area under a statistical distribution of hearing levels in which the hearing threshold level is above 25 dB. These areas, normalized to 100 individuals, can be calculated for both non-noise-exposed populations as well as populations with various noise exposures. The statistical distributions are calculated by the procedures outlined in ANSI Standard S3.44. One minus the ratio of the non-noise-exposed area to the noise-exposed area provides a fair means for the allocation of hearing loss between noise and presbycusis. This approach considers an individual as representative of a group of exposed workers. This idea was first proposed in Air Force Medical Research Laboratory Technical Report No. TR-80-032, September 1983, Wright–Patterson Air Force Base, OH.

EDITORIAL

International Journal of Robust and Nonlinear ControlVolume 7, Issue 6 p. 513-514 EditorialFree Access EDITORIAL C. H. Houpis, C. H. Houpis Air Force Institute of Technology, Wright-Patterson Air Force Base, Ohio, USASearch for more papers by this author C. H. Houpis, C. H. Houpis Air Force Institute of Technology, Wright-Patterson Air Force Base, Ohio, USASearch for more papers by this author First published: 04 December 1998 https://doi.org/10.1002/(SICI)1099-1239(199706)7:6<513::AID-RNC287>3.0.CO;2-DAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume7, Issue6June 1997Pages 513-514 RelatedInformation

The effect of stress ratio on fatigue crack growth rate in the absence of closure

A fractographic study1This investigation was conducted at the Materials Directorate of Wright Laboratory at Wright-Patterson Air Force Base, OH, USA, under contract F33615-94-C-5200.1 was performed on Al-alloy fatigue fracture surfaces produced by programmed load sequences. The load sequences included steps of constant amplitude cycles at three different stress ratios, each step is preceded by a small number of high amplitude cycles designed to avoid the influence of crack closure and to serve as fractographic markers. The experiments were conducted on different specimen geometries to produce conditions associated with a long crack under fully elastic conditions and a short crack in a notched coupon seeing high local post yield stress conditions. Crack sizes covered in the study ranged from 0.02 to 12mm, and growth rates ranged from 2×10−7 to 4×10−5mmcycle−1. Fractographic evidence from the study suggests that the crack growth rate can vary by up to a factor of five with applied stress ratio change from 0.64 to 0.73. In the case of the long crack, the effect is less noticeable or totally absent. In the case of naturally initiating notch root cracks, the effect is more pronounced at higher stress level and lower crack growth rate.

Differential Mass and Energy Balances in the Flame Zone From a Practical Fuel Injector in a Technology Combustor

This paper presents further analysis of experimental results from an Air Force program conducted by researchers at Brigham Young University (BYU), Wright-Patterson Air Force Base (WPAFB), and Pratt and Whitney Aircraft Co. (P&amp;W) (Hedman et al., 1994a, 1995). These earlier investigations of the combustion of propane in a practical burner installed in a technology combustor used: (1) digitized images from video and still film photographs to document observed flame behavior as fuel equivalence ratio was varied, (2) sets of LDA data to quantify the velocity flow fields existing in the burner, (3) CARS measurements of gas temperature to determine the temperature field in the combustion zone, and to evaluate the magnitude of peak temperature, and (4) two-dimensional PLIF images of OH radical concentrations to document the instantaneous location of the flame reaction zones. This study has used the in situ velocity and temperature measurements from the earlier study, suitably interpolated, to determine local mass and energy balances on differential volume elements throughout the flame zone. The differential mass balance was generally within about ±10 percent with some notable exceptions near regions of very high shear and mixing. The local differential energy balance has qualitatively identified the regions of the flame where the major heat release is occurring, and has provided quantitative values on the rate of energy release (up to −400 kJ/m3s). The velocity field data have also been used to determine Lagrangian pathlines through the flame zone. The local velocity and temperature along selected pathlines have allowed temperature timelines to be determined. The temperature generally achieves its peak value, often near the adiabatic flame temperature, within about 10 ms. These temperature timelines, along with the quantitative heat release data, may provide a basis for evaluating kinetic combustion models.

Modeling and simulation of metal forming equipment

The demand for components made from hard-to-form materials is growing, as is the need to better understand and improve the control of metal forming equipment. Techniques are presented for developing accurate models and computer simulations of metal forming equipment for the purpose of improving metal forming process design. Emphasis is placed on modeling the dynamic behavior of hydraulic vertical forge presses, although similar principles apply to other types of metal forming equipment. These principles are applied to modeling and simulation of a 1000 ton forge press in service at Wright-Patterson Air Force Base, Ohio, along with experimental verification.