bluuebunny/crossref_metadata_2025 huggingface dataset:
Forty Years of Thinking in Front of the Alps: Saussure's (1796) Unpublished Theory of the Earth
Authors: Carozzi Albert
Published: April 2015

The four volumes of Voyages dans les Alpes.. published by Horace Bénédict de Saussure (1779-1796) consist of the description of seven trips, organized chronologically only in part. A large portion of Saussure's descriptions represents a composite assemblage of observations and interpretations, often not updated, borrowed from numerous itineraries, repeated many times during various years. The planned theory of the earth, mentioned repeatedly throughout the volumes, is replaced at the end by an Agenda or listing of observations to be made by his followers as a basis for this theory.

Circumstances and poor health prevented Saussure from writing his theory. Fortunately, all his personal papers have been preserved, and among them are carefully-dated field notes and short memos summarizing his ideas at a given time. These documents allow one to reconstruct the evolution of his geological thinking and to present what his unpublished theory, based mainly on the structure of the Alps, might have been.

Several phases in Saussure's thinking show his struggle to untangle himself from a pre-Wernerian to Wernerian heritage, and to break new ground dictated by his observations. These phases are discussed in chronological order under headings describing Saussure's new ideas.

Two versions (1786 and 1796) of the table of contents of Saussure's incomplete theory of the earth indicate the evolution of his synthesis toward a mature and almost modern outlook of planet earth.
Geology, Time and History
Authors: Schneer Cecil
Published: April 2015

There is evidence of consciousness of natural time as far back as the Early Ice Age in recorded observations of the recurrent and successive appearances of the moon. The idea of geologic time was broached as part of the 17th century scientific revolution in the same milieu as the ideal time of rational mechanics, but the sense of time drawn from observations of the earth transcended the limitations of ideal physical law. Inapplicable to "…an unlimited assemblage of local instabilities…" (Maxwell, 1877 p. 14), the laws of physics by definition are independent of the very particulars of time and place that are the essence of historical science. In the 18th century, Hutton formulated a physically dynamic theory of earth history as an indefinitely repeating series of cycles, while continental geologists such as Arduino and Werner constructed an ordinal classification of the major rock formations from primary crystalline basement to the alluvium of the present surface. The detailed scale of geological time as expressed in the geologic column was made possible by the discovery (principally by G. Cuvier and A.Brongniart and independently W. Smith) of the principle of faunal succession. By 1836, a consensus on the main outlines of the structure and biologic, as well as lithologic, succession was reached that held almost up to the present day. With temporal succession, the static scala naturae of Aristotle became first the progressionism of the great chain of being and finally, Darwinian evolution. The idea of geologic time encompasses all that we have learned of the history of our earth and its life.
Problems of Time in Geology
Authors: Milanovsky E.
Published: April 2015

Geology occupies a special position among the natural sciences because of the great importance attributed to the time factor in it. A main goal of geology is reconstruction of the most probable detailed and reliable history of the Earth, based on well-grounded geochronology. This paper contains a short historical review of the evolution of ideas on the Earth's duration of existence, on geological time and its measurement from the old myths and thoughts of ancient philosophers to the notions in modern Earth Sciences, and a brief discussion of some aspects of measuring geological time on the basis of study of different natural processes.
Earliest History of Vertebrate Paleontology in Utah: Last Half of the 19th Century
Authors: Miller Wade , Hall Dee
Published: April 2015

Aside from the recorded travels of Juan de Rivera in 1765 and the Dominguez-Escalante party in 1776, the earliest reports involving explorations into Utah were mostly those for proposed railroad lines and trade routes, or for general knowledge of the poorly known Western Territories (1840s to 1870s). These explorations were usually conducted under the auspices of the United States Army. Scientists, including geologists/paleontologists, commonly accompanied the survey parties. The first surveys whose prime objectives were to study geology and topography were commissioned by Congress in 1867.

The earliest discovery of a vertebrate fossil in Utah apparently took place on the J. N. Macomb expedition of 1859 (which generally followed the Old Spanish Trail), when J. S. Newberry collected dinosaur bones in the southeastern part of the state. F. V. Hayden's 1870 survey may have extended into northernmost Utah. It is possible that a few of the Eocene age fossils which were reported by him from southernmost Wyoming, came from here. Fossils collected during the Hayden survey prompted a vertebrate fossil collecting trip headed by J. Leidy into the same area two years later. Also in 1870, O. C. Marsh discovered and named the Uinta Basin, making a significant fossil vertebrate collection there. Numerous Eocene mammals as well as reptiles and fish were collected in the Basin proper, while a turtle shell and dinosaur teeth were recovered from the upturned Mesozoic beds on the eastern rim of the Uinta Basin. A Jurassic crocodile humerus was found by Marsh along the eastern flank of the Uinta Mountains. In subsequent years before the turn of the century several institutions sent paleontological parties into this area. E. D. Cope in 1880 identified fossil fish and a crocodile from Eocene deposits of central Utah. Pleistocene mammals were first reported by P. A. Chadbourne (1871) and C. King (1878) from Salt Lake and Utah valleys.

While early expeditions for vertebrate fossils concentrated largely on adjacent states, many of America's prominent 19th Century vertebrate paleontologists collected fossils in Utah. Their work pioneered the way for present-day paleontologists.
American Geological Investigations and the French, 1750-1850
Authors: Taylor Kenneth
Published: April 2015

By the middle of the nineteenth century, leaders of the French geological community were taking a keen interest in North American geological phenomena and investigations. Most of this French attention to American geology developed during the first half of the nineteenth century. French geological preoccupations in America during that period tended to focus especially on issues of stratigraphic correlation and paleontology, with discernible concern also for the North American glacial (drift) phenomena, mineral ores, and meteorite observations. The growth of French regard for American geologists and for America as a geological resource, up to 1850, displays features of international cooperation and communication especially plain in such a location-specific science. Historical development of communal scientific activity is seen in travel accounts, and in exchanges of publications and specimens. The Société Géologique de France, founded in 1830, quickly became an important vehicle for commerce in geological knowledge between America and France. French respect for American geological work in the first part of the nineteenth century illustrates the comparatively early maturity of American geological science.
German-Brazilian Relations in the Field of Geological Sciences During the 19th Century
Authors: de Mendonça Figueirôa Silvia
Published: April 2015

This paper analyses the German presence in the development of geological sciences in Brazil during the 19th century, taking into account the local situation - for Brazil was Portugal's colony until 1822 - as well as the importance of mineral extraction activities which played an embryonic role in that process. The German-Brazilian geoscientific relations may be classified as follows: Brazilians sent to visit and to study in German institutions, especially in the Bergakademie Frieberg; German functionaries invited by the Portuguese government to work in mining activities in Brazil; German travelers in Brazil; exchange of geological and mineralogical samples; Brazilian geological problems studied by German scientists.
A Fundamental Overview of Accelerated Testing Analytical Models
Authors: Caruso Hank , Dasgupta Abhijit
Published: April 2015

This paper describes analytical models that are commonly used for product life estimation and accelerated life testing. Model descriptions include: Miner's "Rule" for describing accumulated fatigue damage; Coffin-Manson nonlinear power law, often applied to mechanical fatigue damage; Rudra model for CFF failures; Arrhenius steady-state temperature acceleration model for estimating chemical aging effects; Peck's model for accelerated combined temperature-humidity effects; and Kemeny model for combined temperature and voltage acceleration effects.

The general form of these models will be presented along with specific guidance regarding: relative strengths and appropriate applications for each model; limitations and sources of uncertainty for each model; and example values for exponents and material coefficients.
A Sampling System for Measurement of Nanometer-Sized Particles in Hydrogen
Authors: Malczewski Mark , Holmer Arthur , Demmin Hollis
Published: April 2015

Particle counting in reactive gases such as hydrogen and oxygen utilizing condensation nucleus counter (CNC) technology is now possible with counters such as the CPC 7651 being commercially available. Described here is a sampling system that allows these counters to be used for continuous monitoring in hydrogen and oxygen.

A closed sampling system is described which maintains the inlet of the particle counter at slightly above atmospheric pressure, utilizing sample gas pressure to maintain the proper sample flow rate. This avoids the use of a sampling pump which is a potential ignition source when used with reactive gases. For continuous monitoring applications, refilling of the working fluid during operation is necessary. A pressurized fill system is also described which allows a counter to be refilled against the elevated pressure at the sample inlet. The fill system provides an inert gas above the working fluid and can also be used to refill multiple particle counters.
Control of High-Intensity Acoustic Test Environments
Authors: Noreen R. , Mayne A. , Slone R.
Published: April 2015

Growing demand for commercial and defense satellites has resulted in a recent, dramatic increase in the demand for new high-intensity reverberant acoustic test facilities. During the past two years, three new acoustic test facilities representing a wide range of test capabilities were developed. These facilities differed significantly in the complexity of the noise generation systems, and thus the degree of spectral control that could be achieved. Control of the acoustic spectrum is accomplished by combining noise sources and components with limited capabilities into individual control bands in a manner that yields the desired overall performance. The paper shows the physical parameters involved that limit the performance capabilities of the components. Control requirements are developed for multiple bands through example calculations for an assumed acoustic facility model.
Particle Transmission Through a Turbo Pump
Authors: Kinney Patrick , Pui David , Liu Benjanin
Published: April 2015

Experiments were performed to determine if small particles are capable of passing through a turbo-molecular vacuum pump. A test aerosol was generated at atmospheric pressure and injected into the vacuum system upstream of the turbo pump. Particles were measured immediately upstream and downstream of the turbo pump using two laser-based vacuum particle detectors. Tests were performed with solid and liquid particles. Solid particles were found to pass through the pump, although the efficiency of transmission is not known. Liquid particles did not pass through the pump. These results indicate that vacuum particle counters employed downstream of turbo pumps may be sensitive to upstream particle levels.
A Gas Diluter for Measuring Nanometer-Sized Particles in Oxygen or Hydrogen
Authors: McDermott Wayne
Published: April 2015

A laminar flow diluter tube was designed and tested. The tube dilutes reactive gas aerosols in nitrogen using molecular diffusion. No turbulent mixing of the gases occurs in the tube. The gases are diluted without substantially changing the particle concentration of the sample. The diluted gas can then be measured using an inert gas particle counter. A numerical model predicted the molecular diffusion and particle transport behavior of the tube. Experimental tests confirmed the predictions. The tube diluted sample hydrogen to a concentration of 6.5 percent and oxygen to a concentration of 17 percent. The same tube transported particles smaller than 10 nm with greater than 78 percent efficiency. Therefore, the diluter can be used with particle counters designed for nanometer-size sensitivity. The laminar flow diluter can be used to measure contaminant particle concentrations in filtered reactive gases. Such filtered gases are typically used in microcircuit fabrication.
Temperature Response Characteristics of Various Vibration Isolators
Authors: White George
Published: April 2015

Four types of vibration isolators were characterized to determine whether the system using them could survive Arctic operation. Previous operation in a desert environment had been performed without difficulty. It was predicted that Arctic operations would be successful based on desert and laboratory information. Data at various temperatures were gathered in the lab, and power spectral density (PSD) data, transfer functions, and fatigue ratios were used to predict responses at Arctic temperatures. Predicted Arctic responses exceeded desert responses in some frequency regions, and it was determined that additional testing at Arctic temperatures was warranted.
Theoretical Study of Molecular Contamination on Silicon Wafers: Kinetics
Authors: Zhu Sheng-Bai
Published: April 2015

In an earlier paper ["Theoretical Study of Molecular Contaminants on Silicon wafers: Interactions Between Molecular Contaminants and the Silicon Surface," Journal of the IEST, July/August 1998] a simple formulation was developed to describe interactions between gas phase molecules and solid surfaces.1 Adsorption energies of various organic/inorganic molecules on silicon wafer surfaces were derived, In this paper, the relationship between the gas phase molecule concentration and the surface contamination density based on simple kinetic theories is established. The most important approximations in this derivation include the neglect of possible chemical reactions on the surface and the assumption that gas phase concentrations of pollutants are constants, both in time and in location. The mass transport mechanisms are ignored. With these approximations, the equilibrium in surface kinetics can be reached almost instantly for all the molecules investigated, even for those having activation energies as high as ∼ 72 kJ/mole. This agrees with the experimental data for moisture adsorption on stainless steel.2 A guide is provided for material selection.
Use of a Zero-Gravity Suspension System for Testing a Vibration Isolation System
Authors: Idle M. , Cobb R. , Sullivan J. , Goodding J.
Published: April 2015

The Air Force Research Laboratory team has been confronted with many unique testing challenges in the Ballistic Missile Defense Organization sponsored Vibration Isolation and Suppression System (VISS) performance test program, VISS incorporates a combination passive/active vibration mitigation technology in a Stewart platform configuration to provide a mechanically quiet platform for a medium-wavelength, infrared camera.

VISS actuator stiffnesses, insufficient to support the payload in a l-g field, require a gravity off-load system to simulate the free boundary conditions of space A performance test series characterized the test fixture dynamics, VISS payload dynamics and the open loop control system plant.

Passive performance has been characterized and the active performance measured in the laboratory will be verified when VISS is on-orbit. VISS goals include demonstrating good passive-based vibration isolation at high frequencies, augmenting low-frequency isolation with closed loop control, suppressing an on-board disturbance due to a cryocooler, and demonstrating steering capabilities of the payload with a prescribed amplitude and spectral content.
Investigations of Particle Penetration in Fibrous Filters: Part II. Theoretical
Authors: Dhaniyala Suresh , Liu Benjamin
Published: April 2015

This article is the second part of a two-part series. The first part, "Investigation of Particle Penetration in Fibrous Filters: Experimental," appeared in the January/February, 1999, issue of the Journal of the IEST.

The performance of seven state-of-the-art air cleaning filter media having a wide range of filter efficiencies is described. The figure of merit values have been obtained to compare the performance of different media. The experimentally obtained pressure drops and the theoretically calculated fiber drags are used in deriving an expression to calculate an equivalent fiber diameter for different media. The theoretical values of fiber diameter compare well with the experimental observations. Use of the equivalent fiber diameter values in calculating the parameters of the dimensionless correlation model results in better agreement between the experiments and theory. The calculated equivalent fiber diameter is useful in predicting the most penetrating particle size of different media.
Ground Simulation of Space Radiation Effects on Nonmetallic Materials: Status of the Proposed ISO Standard
Authors: Briskman Boris , Borson Eugene
Published: April 2015

Russia has proposed a new international standard for the testing of nonmetallic materials to simulate space radiation effects. The proposal was submitted to ISO (International Organization for Standardization) Technical Committee 20 (Aircraft and Space Vehicles), Subcommittee 14 (Space Systems and Operations) and was approved as Working Draft 15856 at the Los Angeles meeting (1997). The second version of the draft was approved at the Beijing meeting (1998).
Combined Loads, Vibration, and Modal Testing on the QuikSCAT Spacecraft
Authors: Scharton Terry , Vujcich Michael
Published: April 2015

Combining the quasi-static loads, workmanship verification, and model validation tests of aerospace hardware into a single vibration test sequence can reduce schedule and cost considerably. The enabling factor in the implementation of the combined dynamic testing approach is the measurement of the dynamic forces exerted on the test item by the shaker. The dynamic testing of the QuikSCAT spacecraft is discussed as an example of a successful combined loads, workmanship, and model validation test program.
Measuring Particles and Bubbles in Process Chemicals at Controlled Temperatures
Authors: Xu Mindi , Li Wei-Ching
Published: April 2015

Microbubbles in semiconductor manufacturing process chemicals can be produced by mechanical disturbance to the chemicals or by changing the temperature and pressure. Bubbles suspended in liquid are easily miscounted as particles when an optical particle counter is used for measuring particles. A new technique, controlling sample temperature, has been developed. Samples for measuring particles are refrigerated to a temperature that eliminates bubbles and then introduced into a particle counter for measurement. The results from these experiments indicate that sample temperature strongly affects the particle counts due to the bubbles in the liquids. Effective temperatures for bubble suppression in several process chemicals have been selected based on the experiments. To better understand bubble suppression by controlling temperature, theoretical simulations for the microbubbles in the chemicals were conducted at various temperature conditions. The results from the experiments and the theoretical simulations are compared.
Evaluation of an In-Situ Particle Monitoring System on an MxP Plasma Etch Tool
Authors: Carlberg Jon , Hess Don
Published: April 2015

Etching is the process where a layer is removed from a wafer surface through openings in a photoresist pattern. To monitor this process, a surface scan was employed. An in-situ particle monitor (ISPM) was installed on a plasma etch tool. The ISPM was incorporated so engineers and technicians could gain real-time information and notification of what is happening inside this tool during processing. Since ISPMs are real-time, they can catch problems as they are occurring. The ISPM detected two major problems on the plasma etch tool within a 3-wk period. The wafer scan data were monitored during this same time frame.
Simulated Space Debris Impact Experiments on Toughened Laminated Thin Solar Cell Cover Glass
Authors: Roybal Robert , Tlomak Pawel , Stein Charles , Stokes P.
Published: April 2015

Increasing demands on the design criteria of spacecraft components have driven efforts to develop advanced space debris ground simulation techniques suitable to be incorporated into a space environmental effects chamber. A laser-driven flyer method suitable in such a chamber was used to conduct an initial investigation of space debris impact on a new toughened solar cell coverglass material. Damage characteristics, including mechanical damage and contamination generated by impact with a 3-mm diameter, 3-μm thick aluminum particle accelerated to 4.5 km/sec, were investigated. Scanning electron microscopy, optical microscopy, and spectrophotometry were used to measure the mechanical damage and the loss of solar transmission. Because of the limited number of impact tests made in this initial study, a quantitative analysis was not possible. However, much insight was obtained from the observed damage.
Environmental Simulation for Safe Preservation of Wet Mummies: The Case of 'Ötzi,' the Man from the Ice
Authors: Angelantoni Gianluigi
Published: April 2015

Archeological signs of the past can be impressive when discovered but the first question that arises is how to preserve them for the future. In particular, when organic materials, such as human bodies, are discovered, the technical issues relevant to the preservation environment become critical and the design requirements are often opposed to the physical laws. One of the most important discoveries in this area was "Ötzi." the man from the ice, a 5,500-year-old mummy found in the Similaun glacier. The peculiarity of this mummy is that it is "wet." not "dry" like Egyptian mummies. To preserve this treasure, which is a witness to human evolution, a special thermal safe had to be designed and manufactured. This safe is currently maintained in the museum of Bolzano, Italy. Environmental chamber technology has been used as a baseline to implement a state-of-the art preservation system which demonstrates that wet mummies can be preserved and, at the same time, be displayed for future generations
Environmental Stress Screening vs. Product Life Consumption
Authors: Caruso Hank
Published: April 2015

The question of how much product life environmental stress screening (ESS) will consume is neither simple not straightforward. Adopting simplistic rules of thumb invokes the assumption that all products are the same and homogeneous. This paper discusses the issues involved with assessing the potential impact a particular ESS regimen has on a product's useful life: a) How do we define product life?; b) What environmental loads are applied during ESS?; and c) How will the product be affected and to what degree? Several options for dealing with product life consumed during ESS are discussed.
Determining Vehicle Sensitivity to Changes in Test-Course Roughness
Authors: Connon William
Published: April 2015

Test courses are monitored at the U.S. Army Aberdeen Test Center (ATC) on a monthly basis and are altered as required to maintain a "constant" roughness. The monitoring process consists of a jury ride and analysis of data acquired using an instrumented, light wheeled vehicle. The surface profiles of test courses at ATC are also measured on a monthly basis using a profilometer. A series of displacement and angular measurements are made. These are used to compute surface roughness as a function of distance traveled over the test course. This article proposes two techniques for determining vehicle sensitivity to changes in test-course roughness (vehicle-dependent ride quality and vehicle-independent fatigue damage spectrum) and, thus, the requirement to maintain the course. Both of these techniques require a data transformation in the spatial domain analogous to the power spectral density function in the temporal domain. An example using data measured before and after grading of an actual test course is presented.
Size Distributions of Particles Extracted from Different Materials Compared with the MIL-STD-1246 Particle Size Distribution
Authors: Welker Roger
Published: April 2015

MIL-STD-1246 particle-size distribution is the basis for specifying the particle cleanliness of surfaces for many governmental and industrial applications. MIL-STD-1246 states that naturally occurring particle contamination on surfaces follows a log-normal particle-size distribution, with a geometric mean of 1 μm, following a very precise size specification. However, the naturally occurring particle-size distribution may be a function of the material under examination or the prior cleaning or surface treatment history of the material. This paper explores the relation between the MIL-STD-1246 particle-size distribution and particle-size distributions measured after extraction followed by liquidborne particle-size distribution analysis.
Evaluating the Effects of Flow Rate Reduction on the Environmental Parameters of an Operational Cleanroom
Authors: Jue Michael , Wang Richard , Huang Tom , Fillipovic Anto , Hundt Andreas , Cooper Douglas
Published: April 2015

This article provides results of measurements made to characterize the effects of lowering the HEPA filter air velocity in a operational semiconductor facility. Reduction of HEPA filter velocity can reduce energy consumption by lowering the power consumption of recirculation fans. Data were collected for the cleanroom base HEPA velocity condition. The same data set was collected for conditions of reduced HEPA filter air velocity. Comparison of the data distinguishes changes between different operational air velocities. There is significant variation in the measured values for HEPA filter velocity attributed to technique and facility parameters. When air velocity is reduced below an optimum value, airborne particle counts and variation in the counts increase. Lowered air velocity also affects total adsorbed vapors, the drain rate of charged wafers, and electrical power consumption of recirculation air handlers. For other measured parameters, a difference can be observed but the practical effect on the product can be considered negligible.
Evaluation of Outgassing Compounds from Cleanroom Construction Materials
Authors: Takeda Kikuo , Mochizuki Ai , Nonaka Tatsuo , Matsumoto Ikuko , Fujimoto Taketoshi , Nakahara Taketoshi
Published: April 2015

The control of organic outgassing from cleanroom construction materials is becoming stricter, as semiconductor device geometries continue to shrink. In this article, a dynamic headspace sampling technique coupled with gas chromatography-mass spectrometry (GC-MS) was studied for evaluating cleanroom construction materials. With this method, the outgassing amount increases linearly with increasing sampling time. The outgassing rate is determined from the slope of this curve. The logarithm of the outgassing rate shows a linear relation with a reciprocal number of the absolute temperature of outgassing. By using this relationship, the outgassing rate of materials at temperatures of interest can be estimated from the available data.
Design and Validation of the University of Naples Space Magnetic Field Simulator (SMAFIS)
Authors: Pastena M. , Sorrentino L. , Grassi M.
Published: April 2015

This paper discusses the design and validation of the space magnetic field simulator at the university of Naples. The simulator is designed to reproduce, with predetermined uniformity, the magnetic field vector as sensed by an orbiting satellite in the an assigned volume about the simulator's geometrical center. The simulator will be used primarily for ground testing the magnetic attitude control subsystem onboard the university microsatellite SMART. The paper describes the criteria as well as the mathematical model used for the simulator design. The design aims mainly at developing a simulator configuration that maximizes the volume in which the desired magnetic field vector is realized with a predetermined uniformity with respect to a nominal field. The simulator is configured as an open-loop system, in which fixed currents are used to nullify the local magnetic field. Precision currents are then added to the fixed ones to accurately reproduce, in the test volume, the in-orbit magnetic field vector variation. Results of the simulator validation tests are presented.
Use of Computational Fluid Dynamics Applications in Cleanroom Design
Authors: Lei Tink-Kwo
Published: April 2015

A Computational Fluid Dynamics (CFD) commercial program was used to assist in the design of a Class 1 cleanroom. Two cases were studied. The first case included the design of a modular plenum system. The impact of the size of each plenum module on the modular plenum system performance was studied. A 33-percent less pressure drop was achieved when a regularly designed modular plenum system was carefully redesigned. The second case studied the impact of tool geometry and location on the flow patterns and contamination control in a cleanroom. A platform was placed in the cleanroom, and flow simulations by the CFD program were performed. Flow laminarity in the cleanroom was investigated for two designs. These are primarily the same except that one has the platform located so it is in direct contact with the cleanroom wall and the other has the platform 30.5 cm (12 in.) away from the cleanroom wall. It was observed that the design with a gap between the platform and the cleanroom wall significantly reduced the air turbulence above the platform compared with the design with no gap. A platform made of 55-percent perforated plates was shown to be highly efficient in reducing the air turbulence both above and below the platform in both designs.
Improving the Repeatability and Reproducibility of the Helmke Drum Test Method
Authors: Elion Jenni , Ensor David , Berndt Chuck , Bovino Mike , Diener Roger , Ely Gordon , Eudy Jan , Giroux Robert , Rataj Mike , Witt Jean
Published: April 2015

The Helmke Drum test method, described in IEST-RP-CC003.2, Garment Systems Considerations for Cleanrooms and Other Controlled Environments, is used to measure particle release greater than 0.5 micrometers (μm) from cleanroom garments. During the current effort to revise IEST-RP-CC003.2, it became clear that the method as currently written required revision. Under "Description of Test Limitations," the current method mentions a 1991 interlaboratory comparison (ILC). However, results from that ILC were too variable to allow meaningful interpretation. A cursory look at the results from this 1991 ILC suggested that a re-evaluation of the data using the statistical analysis outlined in ASTM E691 might yield new insights. The Helmke Drum subcommittee of IEST Working Group 003 proposed several changes to the method and a second ILC was conducted in 2001, in which six participating laboratories tested garments per the revised method. A comparison of the statistical analysis of the 2001 results with the statistical analysis of the 1991 ILC shows the revised method yields more repeatable and more reproducible results. The proposed revisions to the method are expected to be adopted by the IEST Working Group and incorporated into the rewrite of the Recommended Practice.
Certification of 200,000 g Shock Calibration Technique for Sensors
Authors: Bateman Vesta , Thacker Philip
Published: April 2015

A split Hopkinson bar technique has been developed to evaluate the performance of accelerometers that measure large amplitude, up to 200,000 g, mechanical shock pulses. An evaluation of this technique has been conducted in the Mechanical Shock Laboratory at Sandia National Laboratories (SNL) for use as an accelerometer calibration technique. Results of this evaluation are presented and include a comparison with a NIST calibrated reference accelerometer. The certification of split Hopkinson flyaway technique by the SNL Primary Standards Laboratory is presented in this paper.
Internet Data Centers and the Infrastructure Require Environmental Design, Controls, and Monitoring
Authors: Frith Clifford
Published: April 2015

Internet technology requires new facilities and infrastructure similar to the data centers for mainframe and supercomputers of the early 1990s. Internet Data Centers (IDC) and the infrastructure require environmental design, controls, and monitoring. Specifications and standards need to be developed, and specialists from the environmental sciences with knowledge and skills are valuable resources.

Security and environmental controls, as well as reliable, redundant connectivity and electric power must be monitored and evaluated periodically. Industry standards must be developed to achieve the high level of performance for mission-critical Internet applications.

This presentation provides an overview of systems, processes, monitoring, and controls required to achieve a reliability level of >99.999% to support business-to-business Internet applications.
End-to-End Mechanical Calibration of Strain Channels in Dynamic Health Monitoring Systems
Authors: Banaszak David
Published: April 2015

The U.S. Air Force invented a calibration technique that allows one person to perform multiple, mechanical end-to-end calibrations of structural dynamics measurement systems. In Order to define the vibrations and acoustics environment, often an aircraft or engine structural health monitoring system collects airframe or engine structural integrity data. A recommended practice is to perform an end-to-end mechanical calibration of the system. This means a full calibration of instrumentation from the physical input to the transducer to the output where the analog or digital signal is normally analyzed. It is difficult to stimulate mounted and embedded transducers with a known physical input, especially strain gages bonded to a structure. This new technique uses a remote control structural exciter (RCSE) to stimulate transducers in structures, with a measurable input level, and the output signal is communicated to the data storage device of the structural health monitoring system. The Air Force demonstrated this patented technique by using accelerometers in the laboratory. This paper investigates this new technique to evaluate and calibrate strain gages mounted on structure. A reference piezoelectric strain gage measures the input. A typical system may include dynamic strain gages connected to a battery operated data acquisition system. This paper describes the invention and looks at potential field applications to insure data integrity of strain data in structural health monitoring data acquisition systems on aging commercial and military vehicles. Also, the paper describes a planned design of experiments to evaluate the use of remote control structural exciters for mechanical end-to-end calibration of strain gages in measurement systems.
A Review of Analytical Techniques for Identifying Contaminants in the Semiconductor Industry
Authors: Chia Victor
Published: April 2015

The appropriate analytical technique to characterize contamination requires the correct measurement instrument, together with careful experimental design and data analysis to eliminate random and systematic errors. When selecting the analytical technique for a specific application, it is important to recognize the advantages and limitations of the technique. This paper reviews common analytical techniques to monitor the purity of cleaning chemicals, solvents, and water; cleanroom environment and components; wafer boxes; and wafers. The techniques described are wet chemical analytical methods and microanalytical methods.
Force Limits Measured on a Space Shuttle Flight
Authors: Scharton Terry
Published: April 2015

The random vibration forces between a payload and the sidewall of the space shuttle have been measured in flight and compared with the force specifications used in ground vibration tests. The flight data are in agreement with a semi-empirical method, which is widely used to predict vibration test force limits. The flight measurements are less than one-half of the random vibration loads specified in the shuttle payload design guide. These data are consistent with published data [1]
Adsorption Behavior of Chemical Contaminants by Molecular Simulation
Authors: Godo Masazumi , Takatsuka Takeshi , Tomonari Mutsuya , Miura Kunio , Takami Seiichi , Kubo Momoji , Miyamoto Akira
Published: April 2015

The adsorption process of chemical contaminants on silicon wafers was investigated by using molecular mechanics, molecular dynamics, Monte Carlo method, and computer graphics. The adsorption energy of organic gaseous contaminants, such as DBP, DOP, and D5, on the hydrogen terminated silicon surface and its oxide surface, were estimated and compared. The adsorption energy of chemical contaminants was larger than that of low molecular weight species, such as benzene, H2O and NH3. The adsorption energy on the hydrogen terminated silicon surface was smaller than that on its oxide surface. The equilibrium adsorption amount on the silicon wafer was also calculated. It was indicated that the configuration of the adsorbed DBP molecules over its gas concentration of 1.9x103 ng/m3 showed multi-layer adsorption. It was indicated that adsorption energy and the equilibrium adsorption amount is a good index to estimate the adsorption properties of organic molecules.
Statistical Validation of Structural Dynamics Models
Authors: Urbina Angel , Paez Thomas
Published: April 2015

There is an increasing reliance in the engineering community on the use of mathematical models to characterize physical system behavior. This is happening even though mathematical models rarely simulate real system behavior perfectly. Due to this reliance, we require objective, well-founded mathematical techniques for model validation. This paper develops a formal approach to the validation of mathematical models of structural dynamics systems. It uses a probabilistic/statistical approach to the characterization of an important measure of behavior of dynamic systems subjected to random excitations, and seeks to validate a mathematical model in a statistical sense. An example is presented.
Physics of Failure as an Integrated Part of Design for Reliability
Authors: Snook Ian , Marshall Jane , Newman Robert
Published: April 2015

A study of the use of Physics of Failure (PoF) methods was undertaken as part of a collaboratively funded United Kingdom Government Department of Industry (UK DTI) project for developing a holistic methodology and assessment model for the enhancement of electronics reliability. Several case studies were conducted to review the use of PoF techniques. The study concluded PoF methods, and in particular life modeling, are essential tools in design for reliability. PoF analysis can also be used to establish reliability enhancement testing (RET) and environmental stress screening (ESS) conditions. A guide for the effective use and inclusion of the PoF methods in the product design and development process was developed and described. Use of the techniques facilitates accurate design right, thereby avoiding redesign and retest cycles, with consequent cost savings and reduced product development times. The PoF method has limitations. It is essentially a bottom-up approach assessing time to failure due to known failure mechanisms. Consequently, it is difficult to apply to full systems, has limitations in assessing failure rate prior to the onset of life-limiting wear out, and is dependent on identifying and having a validated model for all potential failure mechanisms.
Numerical Analysis of Microclimate of Desk Displacement Ventilation Using a Zero-equation Turbulence Model
Authors: Zhao Bin , Zhang Zhao , Yang Xudong , Li Xianting , Huang Dongtao
Published: April 2015

A computational fluid dynamics (CFD) program based on a zero-equation turbulence model is used to simulate the microclimate in a model office ventilated by desk displacement ventilation (DDV). DDV is a new ventilation concept that intends to combine the positive features of displacement ventilation and local task ventilation. The CFD model correctly predicts both the thermal plume and temperature stratification, and the calculated air temperature distributions agree with the measured data. The pollutant concentration distribution is further simulated to evaluate the microclimate of DDV. Results show that despite rather large discrepancies between simulated velocity distributions and experimental data, the zero-equation turbulence model may simulate the main characteristics (thermal plume, temperature, and qualitative velocity tendency) of DDV more quickly than other commonly used models, for instance, the k-ε model, and thus may be applied to similar cases in indoor environment design.
Practical Assessment of Electronic Circuit Cards Under Mechanical Shock Loading
Authors: Stadterman Thomas , Barker Donald
Published: April 2015

This paper presents a practical approach for assessing electronic circuit cards for mechanical shock loading. The approach is comprised of three areas: determining board response, assessing damage to the printed wiring boards, and assessing damage to the components. Determining the board response to the shock loading provides the basis for the damage assessments. To determine board response, the approach recommends specific structures to model and finite element analysis (FEA) methods to use. Failure models for circuit board and component failures are provided in terms of failure risk. To demonstrate this practical assessment approach, an example of a US Army circuit card from a computer assembly mounted on a tracked vehicle is provided. This practical assessment approach will allow electronic circuit card designers to quickly evaluate circuit cards with minimal testing and FEA. It also provides information necessary for circuit card redesign to improve failure risk for shock loading.
Response of Large Membrane Optical Surfaces to Acoustic Environment
Authors: Maahs Gordon , Tolomeo Jason
Published: April 2015

Acoustic launch vibration is often the critical source of vibration for space telescopes. The large surfaces of membrane optics act as receivers of acoustic energy and can experience significant stresses on launch and significant displacements during laboratory testing. Using the finite element software MSC.NASTRAN, several membrane reflector geometries were analyzed under applied axial tension to the membrane surfaces. The pressure field was applied with a sin (kx)/(kx) spatial correlation. Stress and displacements were found at selected points on the membrane surface. Recommendations regarding membrane launch and laboratory testing states are presented in this paper.
Surface Corrosion of HDD Media and Subsidiary Particle Formation Due to SO2 Gas Adsorption
Authors: Namiki Norikazu , Komtasu Akihiro , Watanabe Keiji , Kagi Naoki
Published: April 2015

The storage capacity of hard disk drives (HDDs) for personal computers has increased more than 10,000 times in the past decade. Meanwhile, the gap between the disk and the magnetic head (flying height) has decreased from sub-micrometers to a few nanometers. The lower flying height leads to more sensitive disk-to-surface contamination linked to fatal failures. Many studies have reported that disk surface contamination is related to the adsorption of volatile organic compounds (VOCs) and the corrosion of the magnetic layer of the disk. However, surface contamination derived from sulfur dioxide (SO2) gas in the surrounding area has been discussed insufficiently. In this work, to ascertain the mechanism of disk surface contamination and the subsidiary particle generation, HDD disks were intentionally exposed to SO2 gas, followed by an evaluation of disk operation performance during endurance testing. After the series of endurance tests, a large quantity of sulfate and nickel, which is a main component of the disk substrate layer, was detected on the SO2-contaminated disk surface, as well as a small quantity of cobalt, which is a main component of the magnetic layer. From these findings, the mechanism of surface contamination of HDD disks in the coexistence of SO2 and water was inferred. Nickel is supplied from the substrate layer to the top layer through holes and cracks in the films of disks because of the corrosion triggered by adsorbed water. High temperature and humidity causes the desorption of SO2 from SO2-contaminated disk surfaces to react with nickel. Eventually, the products of nickel sulfate are precipitated on the surface to be released in the form of particles by contact with the head.
An In-Depth Assessment of Internal Contamination in the Wide Field/Planetary Camera: Republished from the Journal of the IES May-June 1990 issue, pages 29-35
Authors: Maag Carl , Millard Jerry , Anderson Mark
Published: April 2015

Following thermal vacuum/thermal balance testing, a gray haze was discovered on the corners of the Wide Field/Planetary Camera (WF/PC) aperture window. The phenomenon was suggested to be a result of molecular transport from a low outgassing structural adhesive. Detailed analyses, both chemical and analytical, were conducted to assess the formation of the haze. Each material was considered individually, as it was not known if the actual contamination was a result of one, many, or possibly none of the materials considered. Results of the analytical assessment and the comparison with the aforementioned chemical analyses provided incontrovertible evidence as to the cause of the window haze. The resultant cleanup and subsequent elimination of the problem are also addressed. [Editor's Note: This 1990 paper is republished as part of the Journal of the IEST 50th anniversary celebration. It is accompanied by remarks from Patti Hansen, author of "Overview of the HST Contamination Engineering Program at 15 Years: A Cleanliness Metric for Success with Optical Satellites" paper in this issue.]
Design Characterization
Authors: Roy Michael
Published: April 2015

Design characterization test (DCT) is a discovery process that identifies the hardware response, both environmentally and operationally, to selected individual types of forcing functions via a step stress testing methodology. DCT forcing functions stimulate the hardware, and the test item performance is measured, focusing on the test item operating and design limits, with emphasis on identification of the test item operating limit. This dynamic test process systematically identifies, diagnoses, and verifies the design changes that optimize the test item design early in the design phase where these changes are cost effective to implement. DCT improves the designed-in reliability, but does not identify all time- and wear-dependent failure mechanisms. Primary forcing functions are thermal, vibration, and electrical power. Properly applied DCT minimizes design risks prior to releasing a design to manufacturing.
IEST leads ISO 14644 Experts in Focus on Nanotechnology in Cleanrooms
Authors: Dixon Anne , Ensor David , Burrows Roberta
Published: April 2015

IEST has again taken a leadership role in ISO Technical Committee 209 Cleanrooms and associated controlled environments as the committee begins developing standards for the nanoscale.