bluuebunny/crossref_metadata_2025 huggingface dataset:
Uses of History in an Historical Science: Learning from Traditions in Geology
Authors: Johnson Markes
Published: April 2015

Different academic disciplines are affected by their history and react toward history in various and sometimes changeable ways. Geology is by far the most historical science in its operational approach to problem solving. Religious, cultural, and political overtones undeniably permeated many aspects of unfolding geological thought during the last few centuries. Despite these influences, the sustained success of applied geology as a predictive tool for the location of natural resources has generated a highly tolerant climate for pure geological research within a broad array of societal systems. Thus, the main influence of history on the continuing evolution of the discipline has been supportive in a remarkably steady way. Geologists tend to react to their history conservatively, seeking no realignments. This relationship is underscored by the fact that the discipline of geology entered the academic arena only after proving itself in the practical world. Geologists were once the unchallenged students of their own history. Historians of science now claim an increasing, if not exclusive role as interpreters of the more subtle inter-relationships between science and society. Practicing geologists will continue their indulgence in history, however, if only to find a measure of continuity in their work, learn moral lessons about the conduct of their science, and gain valuable career perspective.
The Cartoon "Phillipsia Attacking Griffithides", An Observation on a 19th Century Controversy
Authors: Rushton A.
Published: April 2015

The cartoon "Phillipsia attacking Griffithides" dates from about 1843. It is a humorous comment on a disagreement between John Phillips and Richard Griffith as to the age of some unfossiliferous, supposedly Silurian, strata in south-west Ireland. Fossils depicted in the cartoon are traced to contemporary sources; those represented as witnesses of the dispute are aptly drawn from Murchison's "Silurian System".
Concepts of Natural Law and Time in the History of Geology
Authors: Guntau Martin
Published: April 2015

Our contemporary conceptions of time in terms of geology have developed since the Renaissance. In addition to an adequate notion of the age of the earth, these ideas include different concepts of the nature of geological processes in history. Until the 19th century the different concepts of geological time were determined by views on cyclic processes and processes which have a direction, as well as sequences of events, with or without relations between their various phases. These different aspects of geological thought have finally been incorporated into evolutionary conceptions of geohistory.

Despite objective and epistemological problems, geological laws were formulated in the history of geology such as the law of superposition by Steno in 1669, the law of stratigraphy by Smith in 1799, and the law of development of the earth by Cotta in 1858. Laws of nature are interpreted as essential correlations of a general and necessary nature which exist independently of human cognition. Some fundamental geological processes have not been effective throughout the history of the earth. Presupposing that these processes were governed by natural laws as well, it is inferred that laws of nature exist over certain different periods of time. There are four possibilities of how long laws of nature, or combinations of them, can exist: (1) temporally unlimited existence, (2) existence from the beginning up to a certain point in time, (3) existence from a certain point in time up to the present time, (4) existence over a certain past period of time. Thus the science of geology shows that natural laws are of a historical nature, in that they do not exist eternally nor everywhere.
The Second Jurassic Dinosaur Rush
Authors: McIntosh John
Published: April 2015

The first great North American Dinosaur Rush, begun in 1877 and precipitated by the Marsh-Cope rivalry, was followed by an even greater second Dinosaur Rush, begun just before the turn of the century. The two major principals involved were H. F. Osborn of the American Museum of Natural History in New York and W. J. Holland of the Carnegie Museum in Pittsburgh, but a number of other institutions were also involved, among them the Field Museum in Chicago and parties from the Universities of Wyoming and Kansas. The old Marsh sites at Como Bluff, Wyoming and Garden Park, Colorado were reworked with great success, but many new quarries were also opened, among them, those in the Freezeout Hills and eastern slope of the Big Horn Mountains in Wyoming and the Grand Junction area in Colorado, but most importantly at the two greatest North American Jurassic dinosaur sites: The American Museum Bone Cabin Quarry in Wyoming and the Carnegie Museum Quarry at Dinosaur National Monument in Utah.
Thomas Chesmer Weston and the Red Deer River Fossil Fields
Authors: Russell Loris
Published: April 2015

Thomas Chesmer Weston was an English lapidary, who was employed by the Geological Survey of Canada from 1858. He enjoyed field work and made important collections of minerals and fossils in various parts of Canada. In 1889 he made a boat trip down the Red Deer River of Alberta, assisted by Roderick McKenzie of Red Deer. Weston made important fossil finds on this trip, but his most notable discovery was the "Belly River" fossil field, now the Dinosaur Provincial Park. He recognized that this field was older than that of the "Edmonton Series" of Tyrrell, and predicted that it would be one of the world's great fossil fields, a prediction that his successors have fully confirmed.
The American Countercurrent - Eastward Flow of Geologists and Their Ideas in the Late Nineteenth Century
Authors: Dott R.
Published: April 2015

Whereas the trans-Atlantic flow of geological knowledge previously had been overwhelmingly westward, by the mid-nineteenth century, an eastward countercurrent had begun. That flow increased rapidly after the Civil War, when geology was at the forefront in the maturation of science in America. H.D. Rogers was appointed Regius Professor at the University of Glasgow in 1855. James Hall was chosen to be Organizing President of the first International Geological Congress in Paris (1878) and the first English-speaking foreign correspondent of the Academy of Sciences of France (1884). James D. Dane was almost as well known abroad as Hall, especially for his mountain-building theory. Increasingly, American theoretical contributions had to be reckoned with in such fields as Mountain Building, Structural and Precambrian Geology, Geomorphology and Glacial Geology, and Paleontology. By the first decade of the twentieth century, America had seized the initiative on several fronts, but especially in experimental petrology and physics of the earth's interior through the creation of the Carnegie Institution of Washington.
The Academic Fruits of a Trans-Atlantic Relationship and Frienship Henri Ami and Charles Lapworth
Authors: Hamilton Beryl
Published: April 2015

Correspondence between Henri Ami and Charles Lapworth in the early years of this century illustrates the relationship between science and Empire fostered by both governments and scientific organizations. In a small way, these two men tried to put this ideal into practical terms by attempting to found a research chair at Birmingham, England, using Canadian resources.
Trace Moisture in Ammonia: Gas Chromatography Using Calcium Carbide
Authors: Monroe Susan
Published: April 2015

CaC2 is known to convert water to acetylene by the following reaction.

CaC2 + 2H2O → Ca(OH)2 + C2H2

The conversion rate of water to acetylene is reported to depend on reaction temperature, cell size, flow rate, particle size, and the type of gas studied. Data will be presented quantifying the amount of C2H2 evolved from the reaction of CaC2 with 3 to 10 ppm H2O in both helium and ammonia gas under a defined set of experimental conditions. A calibration curve is presented to illustrate linearity for acetylene detection by gas chromatography/discharge ionization detection (GC/DID) under these experimental conditions down to 15 ppb ±1.5 ppb. Taking into account the stoichiometry of the above reaction, the method could potentially have a sensitivity for water in the range of 30 to 50 ppb.

However, moisture challenges from 3 to 10 ppm in helium and ammonia were detected with an accuracy of only ±1 ppm. the precision of the measurement is a sum of the variance in the moisture input system plus variance in the reaction rate of water with calcium carbide. The reaction in NH3 requires a 2-hr residence time in the calcium carbide reaction cell for the water in the ammonia sample to fully react with the solid CaC2 at 40°C (104°F).
MIL-PRF-1540, A Performance Specification for Design and Product Verification of Space Hardware
Authors: Tanner Carole , Moening Charles
Published: April 2015

Acquisition reform has caused the cancellation or conversion of many military specifications and standards. One of the standards targeted for conversion by Air Force Material Command (AFMC) was MIL-STD-1540. The standard provides details for the testing of launch, upper stage, and space vehicles. AFMC requested that MIL-STD-1540C be converted from a standard to an alternative form of documentation. To answer this request, The Aerospace Corporation and Space and Missile Systems Center used an innovative approach to develop a document that retained the value of the original standard. The new document is MIL-PRF-1540 (a Military Performance Specification). MIL-PRF-1540 is intended for use in the Request For Proposal (RFP) instructions for new procurements of space hardware. The value of MIL-STD-1540C was retained by incorporating it into the already existing MIL-HDBK-340. The revised handbook, MIL-HDBK-340A, is referenced by MIL-PRF-1540 as guidelines only.
Operational Vibration Specification of Helicopter Stores Using Wavelet Analysis
Authors: Hale Michael , Adhami Reza
Published: April 2015

A discussion of classical signal analysis techniques for both stationary and nonstationary data and the corresponding shortcomings of each is available in Reference 24. The earlier work proposed wavelet-based signal analysis as a potential tool in the analysis and specification development of nonstationary vibration events. This paper is a continuation of this work with application toward the operational vibration specification development of nonstationary vibration events measured on helicopter stores. Wavelet analysis will be reviewed and followed by a tailored wavelet-based operational vibration specification proposal.
Miniature Quadrupole Arrays for Residual and Process Gas Analysis
Authors: Boumsellek S. , Ferran R.
Published: April 2015

This paper includes computer simulations based on ray tracing to aid in the design of miniature quadrupoles. These quadrupoles are then assembled in a matrix-like pattern to operate in parallel. The tradeoffs between sensitivity and resolution for different mechanical and electrical configurations are examined using real-time trajectories of ions. The dependence of resolution versus sensitivity is computed and compared with experimental results. The pressure dependence of the sensitivity is simulated near the upper limit (mtorr range) of the operating pressure. Space charge effects at the inlet of the mass filter are evaluated to properly design electrode apertures and spacing. Using the results of ray tracing, miniature quadrupole arrays were designed and constructed. Performance parameters were derived from recorded spectra and compared with the computations. Since they are able to operate at higher pressures, these sensor-type devices are used as residual gas analyzers (RGAs) and as process gas analyzers (PGAs) in many semiconductor applications. Networking multiple sensors to monitor the state of the semiconductor manufacturing tool and the wafers at different stages of the process enables real-time, wafer-to-wafer control using preset fault detection schemes.
Contamination Control for the Earth Observing System (EOS) Multi-Angle Imaging Spectro-Radiometer (MISR)
Authors: Aveni Glenn
Published: April 2015

The contamination control activity performed for the Multi-Angle Imaging Spectro-Radiometer (MISR) consisted of an overall system analysis for susceptibility to molecular and particulate contamination from both internal and external sources at the most sensitive sensor wavelength. This analysis considered the system long and short-term radiometric stability requirements, the expected sources of contaminants, the transport of those contaminants to the sensors, and the expected effects of those contaminants on sensitive surfaces. The derived requirements, including specific budgets, and a plan to meet them during assembly, test, and storage, were documented in the EOS MISR Contamination Control Plan. The final phase of control came from monitoring the hardware (recording data and implementing cleaning procedures) during assembly and thermal vacuum testing prior to shipment to the EOS integrator.
Determining the Dynamic Efficiency of Cleanroom Wipers for Removal of Liquids and Particles from Surfaces
Authors: Oathout J.
Published: April 2015

Three factors are important for removing a liquid from a surface using a wiper, whether that liquid is added to the surface for cleaning or whether it is present as a spill. First is the dynamic absorption efficiency; second is the number of particles present in the spill (or on the surface being wiped) and the extent of removal of particles during the wiping process: and third is the concern regarding particles and fibers which the wiper may leave behind on the surface being wiped. This paper describes new procedures for investigating these factors. Data are presented which demonstrate that cleanroom wipers made from fabrics that "wipe the surface dry" leave the wiped surface cleaner than those which do not because residual contamination from a spill remains in the liquid phase left behind on the surface. The conclusion from these data is that wipe-dry is not only desirable from a housekeeping point of view, but critical for wiping up spills and removing particles from surfaces. The inherent cleanliness of wipers is less important in selecting wiping materials than the ability of the materials to wipe surfaces dry.
Vibration Testing a Large Guided Missile on Air-Spring Supports
Authors: Schwab Harry
Published: April 2015

When performing a vibration test on a guided missile, it is necessary to simulate the free-free condition of the missile in flight. This procedure presents technical difficulties because the missile must be supported for the test in the laboratory, and the supports can affect the mode shapes and resonant frequencies. To avoid the problems that occurred when using slings or bungee cords, an air-spring support system was developed. The performance of the air-spring support system exceeded expectations. The missile could be raised quickly and consistently on the saddles, and the supports had minimal effects on the vibration responses.
Reactivity Monitoring: An Alternative to Gas Monitoring in Semiconductor Cleanrooms?
Authors: Muller Chris
Published: April 2015

One environmental parameter that is increasingly targeted for tighter control in semiconductor cleanrooms is airborne molecular contaminants (AMC). The biggest problem today is not whether specified levels of AMC can be achieved, but whether they can be accurately measured to ensure compliance with any standards or control criteria. A number of manufacturers are turning to environmental classification via reactivity (or corrosion) monitoring. This paper describes reactivity monitoring and examines its use for:

• Performing environmental assessments in cleanrooms as part of contamination control programs based on the presence (or absence) of corrosive AMC.

• Providing the short-term data required to manage and mitigate contaminant-specific episodes.

• Evaluating long-term air quality trends in a facility.

• Conducting research studies designed to determine relationships, if any, between contaminant levels and possible damaging effects.
Vibroacoustic Modeling Study of the Delta II 10-Foot Composite Fairing
Authors: Do Thinh
Published: April 2015

The Boundary Element Method (BEM) has seen increasing use in the space industry to predict vibroacoustic responses of spacecraft and launch vehicle structures. The BEM application is used in the low-frequency regime where Statistical Energy Analysis (SEA) is usually inapplicable. This paper documents a vibroacoustic study of the Delta II 10-ft composite fairing using BEM and SEA. The fairing vibration and internal acoustic levels are predicted. The BEM and SEA predictions are compared with data from the Delta II 10-ft composite fairing acoustic test. The relative accuracy of the BEM and SEA methods in various frequency ranges is discussed. In addition, computer system requirements and lessons learned from BEM and SEA modeling are presented.
Validation of Turbomachinery Computational Fluid Dynamic Models Using Laser Velocimetry
Authors: Ferguson T. , McGlynn R.
Published: April 2015

Computational fluid dynamic (CFD) codes are powerful tools for flow field modeling. The codes, however, must be calibrated with data from actual flows if the predictions of the analysis are to be applied with confidence. Laser velocimetry is one method whereby the predictions of the codes can be anchored with accurate, noninvasive flow-field data. This paper explores the process from initial CFD concerns to the application of the velocimeter in the test facility.
Accelerated Test Techniques
Authors: Raymond Mike
Published: April 2015

Currently there is considerable debate over the relevance and adequacy of emerging vibration test methodologies. This paper details a controlled series of experiments designed to evaluate the nature and consistency of failures produced from several test methodologies including single-axis step stress, skewed-fixture step stress, pneumatic impact, and finite element analysis. Details regarding the test article, individual test methods, and a summary of conclusions are presented.
Optimization of Filter Properties for Recirculating Etch Baths
Authors: Kelly Wayne , Grant Donald , Zahka Joseph
Published: April 2015

Membrane filters are often used to remove small particles from liquids in recirculating etch baths (REBs). The ideal filter for this application would have both high particle capture efficiency and high flow permeability. Unfortunately, filters with high particle capture efficiency often have low permeability because the dominant particle capture mechanism is mechanical sieving. This paper describes more efficient capture mechanisms, interception and diffusion, and a filter with a surface modified to capture particles by these mechanisms. The filter has the same permeability as a conventional 0.45-μm filter and retains particles more efficiently than a conventional 0.05-μm filter. The filter is capable of removing multiple types of small (0.065-μm) particles (polystyrene latex, silicon nitride, alumina, etc.) with high efficiency (> 99.9 percent).
High-Intensity Acoustics Simulated by a Shaker
Authors: Tolomeo Jason , Lee Y.
Published: April 2015

Designing an appropriate shaker random vibration test to accurately simulate a high-intensity acoustic environment is complicated by the fundamental differences in the nature of acoustic excitation and baseshake input, as well as test fixture and boundary condition differences. A coupon random vibration test of a spacecraft panel with an imbedded heatpipe component was performed to simulate the expected acoustic environment at liftoff and flight. Analytical predictions of the acoustic response of the full panel were made and then compared with predictions of the baseshake response of the coupon configuration at specific locations. An appropriate shaping profile was then designed for the random vibration test. The resulting responses produced by the random vibration test were found to be a good representation of the acoustic responses in both overall response levels and power spectral densities.
The Size Distribution of Particles Released by Garments During Helmke Drum Tests
Authors: Ensor David , Elion Jenni , Eudy Jan
Published: April 2015

The Helmke Drum test method to measure particles shed from garments was developed twenty years ago. It consists of a tumbling drum containing the garment under test. A probe connected to an optical particle counter is used to transport the sample from the drum. Dilution air is drawn into the drum from the surrounding cleanroom. The optical particle counters at the time of development were limited in resolution to 0.5 μm diameter. This particle size requirement is still in the current version of IEST-RP-CC003.2, Garment Systems Considerations for Cleanrooms and Other Controlled Environments. A question was raised in the current IEST Contamination Control Working Group 003, "Garment System Considerations for Cleanrooms and Other Controlled Environments," as to whether the method could be extended to smaller particle diameters. The method would benefit by including measurements of smaller particle diameters for two reasons: the higher particle counts expected for sub-0.5 μm particles might improve the statistics of the method; and there is a growing need to consider contamination by ultra-fine particles during the manufacture of high performance products. We hypothesized that the size distribution of particles released by garments follows a power law similar to that for cleanroom classes. The form of the power law distribution is N(d) = Ad(-B), where N(d) is the cumulative concentration greater to or equal to d, d is the particle diameter, and A and B are statistically determined coefficients. The size distributions from a number of Helmke Drum tests were analyzed and were found to be highly correlated to the power law equation. However, the slopes appeared to vary depending on the type of garment tested. These results support including guidance with respect to particle size in the Helmke Drum test section in the upcoming revision of IEST-RP-CC003.2.
The Effect of PAO Aerosol Challenge on the Differential Pressure of an ePTFE Media ULPA (Experimental) Filter
Authors: Roberts Ronald , Arnold Dave
Published: April 2015

A new generic ePTFE (expanded polytetrafluoroethylene) media super ULPA filter was subjected to six hours of continual PAO (polyalphaolefin) challenge to determine the effect on the filter differential pressure and delivered air flow. A continuous challenge concentration of 15 to 16 μg/L was introduced upstream of the filter. To limit the effect of the fan curve, air volume was adjusted to maintain the initial value of 500 f3/min ± 5% for the duration of the study. A volume of 500 f3/min is typical for a terminal housing to limit noise generation in a facility and maximize filter life. Over the test period the air volume and differential pressure were taken every 15 minutes. The results showed a 96% increase in differential pressure over the course of study. As a result of this significant increase in differential pressure, it was determined that the ePTFE is not suited for the intended application requiring semiannual certification using an oil-based aerosol challenge.
Dynamic Modeling and Durability Analysis from the Ground Up
Authors: Stadterman Thomas , Connon William (Skip) , Choi Kyung , Freeman Jeffrey , Peltz Alan
Published: April 2015

Vehicle manufacturers currently use dynamic modeling, finite element modeling, and durability analysis to incorporate reliability into their designs. Although these models are often used separately, there has been little effort toward integrating these analyses and performing an analysis from the "ground up" (i.e., using terrain data to determine dynamic stress and strain). This paper outlines the approach of an ongoing analysis of a US Army trailer, using an integrated process of dynamic modeling, finite element modeling, and durability analysis. This project outlines an approach to mechanical reliability analysis that can be used early in design.
Characterization and Simulation of Gunfire with Karhunen-Loeve Expansion
Authors: Smallwood David
Published: April 2015

Gunfire is used as an example to illustrate how the Karhunen-Loeve (K-L) expansion can be used to characterize and simulate nonstationary random events. This paper will develop a method to describe the nonstationary random process in terms of a K-L expansion. The gunfire record is broken up into a sequence of transient waveforms, each representing the response to the firing of a single round. First, the mean is estimated and subtracted from each waveform. The mean is an estimate of the deterministic part of the gunfire. The autocovariance matrix is estimated from the matrix of these single-round gunfire records. Each column is a realization of the firing of a single round. The gunfire is characterized with the K-L expansion of the autocovariance matrix. The gunfire is simulated by generating realizations of records of a single-round firing from the expansion and the mean waveform. The individual realizations are then assembled into a realization of a time history of many rounds firing. The method is straightforward and easy to implement, and produces a simulated record very much like the original measured gunfire record.
Normalized Error Estimates for One-Third Octave Band Filter Processing
Authors: Merritt Ronald
Published: April 2015

This paper summarizes numerically derived theoretical estimates of normalized random and normalized bias errors for one-third octave band filters applied to autoregressive processes of order two. It demonstrates that one-third octave band estimates of such processes may have substantial bias errors depending upon (1) frequency location of a true spectra peak relative to the center frequency of the one-third octave band filter and (2) half-power bandwidth of the true spectra. One-third octave band processing error is contrasted with narrowband processing error. It concludes that one-third octave band processing should be avoided whenever external information would indicate that the underlying time history data may have a narrowband character.
Sensitivity Analysis of a Microslip Friction Model
Authors: Paez Thomas , Urbina Angel , Gregory Dan , Resor Brian
Published: April 2015

Real physical systems subjected to dynamic environments all display nonlinear behavior, yet they are most frequently modeled in a linear framework. The main reasons are, first, that it is convenient and efficient to solve linear equations, and second, that the system behavior can often be accurately approximated using linear governing equations. Experience shows that much of the nonlinearity of system behavior arises from the dynamic action of mechanical joints in systems. When the linear framework is used, the stiffness of joints is modeled as linear, and the damping is modeled as linear and viscous. To model mechanical joints otherwise requires a nonlinear framework and mathematical finite element model that accommodates transient time domain analysis. This study investigates a particular mechanical joint energy dissipation model: the Iwan model for energy dissipation caused by microslip friction. The sensitivity of energy dissipation in a system due to variation of model parameters is studied. The results of a combined numerical/experimental example that uses a model calibrated to a sequence of experiments are presented.
Comparison of Indoor Environment of a Locally Concentrated Cleanroom at Occupied and Unoccupied Status by Numerical Method
Authors: Zhao Bin , Cao Li , Li Xianting , Yang Xudong , Huang Dongtao
Published: April 2015

The existing standard for cleanrooms is based on an unoccupied state where there are no people or furniture inside the room. However, the distribution of airflow and particles in a cleanroom may differ significantly in an occupied state with the presence of people and furniture. This paper first validates a numerical model for simulating the air distribution in a locally concentrated cleanroom. Then the indoor airflow and the pollutant concentration in a locally concentrated bio-clean operation room (BCOR) are simulated at both occupied and unoccupied states by the validated model. The comparison of results shows the environment is very different between the two cases. Thus, human bodies and furniture should be properly considered when evaluating the environment in the locally concentrated cleanroom.
An Assessment of RPN Prioritization in a Failure Modes Effects and Criticality Analysis
Authors: Bowles John
Published: April 2015

The Risk Priority Number methodology for prioritizing failure modes is an integral part of the Automobile Failure Modes and Effects Analysis (FMECA) technique. This technique consists of ranking potential failures from 1 to 10 with respect to their severity, probability of occurrence, and likelihood of detection in later tests, and multiplying the numbers. The result is a numerical ranking, called the RPN, on a scale from 1 to 1000. Potential failure modes having higher RPNs are assumed to have a higher design risk than those having lower values. Although this method is well documented and easy to apply, it is seriously flawed from a technical perspective, making the interpretation of the analysis results problematic. Problems with the methodology include: use of ordinal ranking numbers as numeric quantities; lack of continuity in the RPN measurement scale; duplicate RPN values with extremely different characteristics; and varying sensitivity to small changes. Recommendations for an improved methodology are provided.
Measurement of Molecular Film Contamination Using Surface Acoustic Wave Microbalances
Authors: Luey Kenneth , Fay Michael , Sly Rusty
Published: April 2015

To ensure the cleanliness of sensitive spacecraft systems, the contamination environment in aerospace cleanrooms and highbays is closely monitored. In this paper, we report the testing and evaluation of a commercially available molecular contamination monitor consisting of a 200-MHz surface acoustic wave microbalance (SAWM). SAWMs were placed into four different aerospace facilities with markedly different environments. SAWMs measured distinctly different molecular film accretion rates consistent with the levels of contamination control and activity in each facility. SAWM results were compared with nonvolatile residue (NVR) accretion rates measured by witness plates. Witness plate data yielded a higher NVR accretion rate than microbalance data. We present evidence that this difference is due to the detection limit of the witness plate analysis technique and not to a fundamental difference in surface deposition processes.
Component and System Life Distribution Prediction with Reliability Demonstration Implications for a Diesel Fuel Injector
Authors: Aldridge Dustin
Published: April 2015

A vehicle case study is used to illustrate a methodology of analysis and testing to predict component and system reliability and durability. The methodology integrates customer usage data, component failure distribution, system failure criteria, manufacturing variation, and customer severity variation. Extending this methodology to the vehicle system level enables correlation between component and system requirements. Further, this analysis provides the basis to establish a knowledge-based test option for a successful test validation program to demonstrate reliability.
Modal Testing and Finite Element Analysis of a Battery Rack for Seismic Applications
Authors: Berak Elzbieta
Published: April 2015

One of the most challenging aspects of reliability testing in the telecommunication industry is earthquake resistance testing. Cabinet systems, battery racks, equipment racks, and distribution frames are considered compliant with Network Equipment-Building System (NEBSTM) criteria for surviving earthquake conditions if test results indicate (1) the maximum deflection of the top of the structure does not exceed 7.6 cm (3 in.), (2) there are no permanent deformations or structural damage, and (3) the equipment or batteries remain functional (as defined in NEBS Requirements: Physical Protection, Specification GR-73 Issue 2). Based on seismic test results of a large population of telecom enclosures, it is accepted that a system always passes the seismic test if its fundamental natural frequency is at least 6 Hz. It is costly to produce and configure enclosures and conduct seismic qualification testing. To minimize the risk of telecom system failure, a modal finite element analysis (FEA) of the system should first be performed. Numerical results of the FEA should then be verified with experimental resonance search data generated by modal testing or sine sweep testing, combined with static pull testing where applicable. The resonance search results will determine the need for seismic testing (seismic analysis) prior to seismic qualification testing. This paper elaborates on key aspects of the static pull test method supported by the test results for a cabinet framework and a configured cabinet relative to the seismic test results. The paper also discusses sine sweep testing of a battery cabinet and results of two modal test methods used on the corresponding battery rack. Finally, this paper describes modal FEA of the same battery rack anchored to a concrete pad supported by a polystyrene plastic foam sheet and explains the correlation of the numerical results with the experimental modal analysis results. The correlated model serves as the baseline model for analyzing other battery racks and equipment cabinets configured with batteries.
Standard Accelerated Life Testing Model Applied to Mechanical Components
Authors: Tebbi O. , Guérin F. , Dumon B.
Published: April 2015

This paper provides an overview of the application of accelerated life testing (ALT) models to mechanical components. Estimates are based upon a classical test plan using a sample system tested under accelerated conditions (not under operating conditions). The time transfer regression model is considered log-linear. The parametric model, proportional hazards (PH) model, and semiparametric model are studied. This paper illustrates an experimental example on a paper clip.
Prediction of Vibration in Bandtrack-Driven Military Vehicles
Authors: McCullough Michael , Simoni Darren
Published: April 2015

Analytical methods for predicting the vibration levels in bandtrack-driven military tracked vehicles are described, contrasted, and compared. These methods range from parametric models superimposed upon existing dynamic simulation models to first principle models developed from direct measurement of suspension and band-track geometric physical properties. The first principle models are implemented in a multibody dynamics computer code for mechanical system simulation and used for predicting vibration, track retention, and rolling resistance.
Aircraft Passenger Cabin ECS-Generated Ventilation Velocity and Mass Transport CFD Simulation: Velocity Field Validation
Authors: Baker A. , Ericson S. , Orzechowski J. , Wong K. , Garner R.
Published: April 2015

A collaborative research project, established between the University of Tennessee (UT) computational fluid dynamics (CFD) Lab and the Federal Aviation Administration (FAA) Civil Aerospace Medical Institute (CAMI), sought to validate CFD prediction of the environmental control system (ECS)-generated ventilation velocity vector flow field of a wide-body aircraft passenger cabin. Measurements generating the experimental database of the time-dependent, three-dimensional velocity vector field were conducted in the CAMI Aircraft Environmental Research Facility (AERF) and in an identical wide-body aircraft in cruise flight at altitude. The CFD simulations were conducted on the CFD Lab resident PC cluster using both commercial and proprietary CFD computer codes. The results of this velocity field validation study reported herein quantitatively assess CFD algorithm/code strengths and weaknesses, and fully confirm the dominance of unsteadiness in the aircraft ventilation velocity field. To be reported in a separate paper are the results of an add-on FAA Cooperative Research and Development Agreement (CRADA) project, which generated a mass transport validation component for a gaseous release into this ECS-generated velocity field.
A Test Method for Measuring Surface Cleanliness with Respect to Nonviable Liquid Contaminants
Authors: Shaffer Lori
Published: April 2015

In cleanroom environments, minimization of surface contamination is critical. As contaminants can be trapped in liquid droplets, the ability of a substrate to remove liquid from a surface is crucial to maintaining the cleanliness of a cleanroom. The focus of this paper is a test method designed to measure the cleaning efficiency of a substrate under various wiping conditions. The intent is to utilize this method to determine the effectiveness of a given cleaning procedure.
Measuring the PWP Improvement in the Handling Component of a Semiconductor Process Tool from Air Ionization
Authors: Levit Lawrence
Published: April 2015

The purpose of this experiment was to assess the importance of electrostatic attraction in contamination control in a semiconductor fab. Wafer handling was studied in a cryogenic cleaning tool in a working 300-millimeter (mm) fab in the United States. The particles per wafer pass (PWP, >200 nanometers [nm]) was reduced from 0.455±0.058 to 0.245±0.046 through the use of air ionization. While the tool is one of the cleanest in the fab, the tool still exhibited a large percentage improvement in contamination level by the addition of air ionization.
Experimental Contribution to the Modeling of Shock Propagation Induced by a Linear Pyrotechnical Source
Authors: Collet Christelle , Chabin Philippe , Grzeskowiak Henri
Published: April 2015

In recent years, the phenomena occurring during shock wave propagation in spatial structures have been studied to characterize more accurately and to minimize the effects of pyrotechnical sources. As part of a program managed by the Centre National d'Etudes Spatiales (CNES, the French space agency), SNPE Matériaux Energétiques (SME) and MBDA France collaborated in a study to understand the mechanisms of shock wave propagation induced by the detonation of a linear pyrotechnical source. The focus of the study was on structures representative of space launcher structures such as those used for the Ariane 5 launcher. Various experiments were performed with metallic and composite plates, and two types of measurement devices (strain gauges and accelerometers) were investigated. Additional out-of-plane velocity and displacement measurements were provided by laser vibrometers, and displays of the separation of the plates were provided by a high-speed camera (up to 4800 feet/second). Signals treatment provided bending and compression strain describing plate mechanical responses. The apparatus used and the associated concerns that arose during the firings also are discussed.
Accelerated Life Test Modeling of Outdoor Optical Products with Time-Varying Multi-Stresses
Authors: Lam Chung , Guo Huairui
Published: April 2015

The long-term performance prediction of optical products deployed outdoors is important. The accuracy of the prediction directly affects warranty cost calculations. In indoor environments, products are generally operated under controlled temperature and humidity. However, products outdoors usually experience multiple stresses that continuously vary with time. An outdoor-use optical product, such as a fiber distribution hub cabinet with splitters, connectors, and fan-outs built in, will experience temperature cycling effects and varying humidity. Therefore, time-varying temperature and humidity are considered as major stresses acting on outdoor-use optical products. This study proposes a practical method that uses design of experiment (DOE) techniques and generalized log-linear (GLL) life-stress relationship to predict the life of outdoor optical products. The proposed method can consider the cumulative damage caused by time-varying temperature and humidity and was applied to predict the warranty return of an outdoor optical product.
Automated CO2 Composite Spray Cleaning System for HDD Rework Parts
Authors: Knoth G. , Jackson D. , Sorbo N.
Published: April 2015

Many advanced assemblies require high-volume and cost-effective selective cleaning during various stages of assembly or rework operations. Due to component compatibility problems and drying challenges, partially assembled devices cannot be immersed in or sprayed with aqueous cleaners or solvents. Newer dry cleaning techniques such as carbon dioxide (CO2) aerosol spray cleaning processes (snow cleaning) have proven to be challenging to implement in automated high-volume manufacturing operations. Issues associated with conventional snow cleaning include high costs of operation, lack of process consistency, ineffective controls, and the requirements for a supply of high-purity liquid CO2.

Advanced CO2 composite spray [CO2(solid)-compressed dry air (CDA)(gas)] cleaning is an effective alternative to traditional spray and immersion cleaning processes and to conventional snow cleaning for selectively removing contaminants and films from partially assembled hard disk drive (HDD) components during the remanufacturing or rework process. CO2 consumption is reduced using a composite spray, while spray cleaning control and performance is improved. CO2 composite spray cleaning performance is dependent on the position, speed, and motions of the spray applicator, which are matched to comply with HDD factory output. Stored spray cleaning programs deliver precise cleaning seven days a week, 24 hours per day, with uptimes exceeding 99.9% over a 6-month period. Monitoring and controlling composite spray cleaning process parameters including spray pressure and composition, scanning speed, and pallet/part identification are done automatically. Operator interaction is limited to loading and unloading pallets for continuous system operation.
Modeling and Adapting Production Environmental Stress Testing
Authors: Joyce Toby , Gaffney Oonagh , Kher Shirish , Wilson Simon
Published: April 2015

This study describes the production sampling environmental stress test (PSEST) process and the offline analysis conducted. Some of the key characteristics and parameters of the test are outlined. The analytical process is based on two types of regression model, each of which links a dependent variable (the log of time to failure in each dwell, or the log of the number failed in each dwell) to independent variables such as temperature and age. These two types of regression are known as Weibull regression1 and Poisson regression.2 Using the estimated regression coefficients, expressions for the probability distribution of a unit under test can be written and used to optimize the test duration.
Electrostatic Control and Air Ionization in Cleanrooms for Semiconductor and TFT Production
Authors: Wei Guan
Published: April 2015

The most critical manufacturing processes for integrated circuits and thin-film transistors, mainstays of the semiconductor industry, take place in cleanrooms. The strictly controlled temperature and humidity in cleanrooms enable electrostatic charges to be generated and maintained on the surface of objects for an extended time. Electrostatic charge and discharge cause particle contamination, damage to products, and electromagnetic interference, which can lead to production tool lockup. With the development of new manufacturing technologies, products are becoming more sensitive to electrostatic discharge. How to control electrostatic charge and eliminate associated problems has become a challenge in the high-tech semiconductor industry.
The Specification of Large Reverberant Acoustic Test Facilities
Authors: Mayne Arloe
Published: April 2015

There is a significant and continuing worldwide interest in large Reverberant Acoustic Test Facilities (RATFs) that subject spacecraft to the simulated acoustic field of a rocket launch. Established companies continue to upgrade their existing RATFs or build new ones. Companies and countries that are just entering the field of spacecraft development must eventually build new integration and test facilities, including RATFs. Acoustic test facilities are rarer than vibration test systems and less well understood in general. Even experienced users typically require assistance during the development of specifications for an upgrade or for a new RATF. This paper provides an overview of some important topics that should be included in the specification of a large RATF, based on the many facilities the author has worked with over the past 23 years. Specific recommendations for certain aspects of an RATF are also included.
Isolation and Identification of Rubisco Extracted from Spinach Leaves
Authors: Weaver Dantel
Published: April 2015

This paper evaluates a laboratory process for extracting, isolating, and identifying rubisco, an essential protein found in plant cells and an important catalyst during photosynthesis. Isolating rubisco from other proteins also found in plants requires a carefully planned series of laboratory procedures to separate the proteins on the basis of physical characteristics including solubility, electrical charge, and molecular size. In this study, ammonium sulfate precipitation was used to extract proteins from a sample of spinach leaves and to separate the proteins into two samples with different solubility characteristics. These samples were then subjected to ion exchange column chromatography using buffers with a range of salt concentrations to produce fractions with varying electrical charge characteristics. The resultant fractions were then analyzed via protein electrophoresis to determine the molecular weight of the isolated proteins, which were compared against the known molecular weight of rubisco. Finally, the experimental results were analyzed to determine which parameters for the ammonium sulfate saturation procedure and the ion exchange column chromatography procedure were most effective at isolating rubisco for future scientific study.
Limitations of the Power Spectral Density as an Indicator of Test Severity
Authors: Paulus Mark
Published: April 2015

This paper presents a set of experimental data comparing repetitive shock (RS) vibration, single-axis electrodynamic (ED) vibration, and multi-axis ED vibration. It was found that multi-axis testing is more severe than single-axis testing at the same level. In addition, weaknesses were found in the RS system at low frequency. Smoothing of the data or poor line resolution was also shown to change the overall severity of a test. A poor correlation was shown between the power spectral density (PSD) and the rate of natural frequency change (RFC) over a wide frequency shift. The change in natural frequency caused the initial PSD to be an ineffective indicator of test severity. Quantification of the severity of the test profile can be accomplished through characterization of the RFC.