bluuebunny/crossref_metadata_2025 huggingface dataset:
Artificial Pith Gallery (APG) construction v1
Authors: Skelton James , Hulcr Jiri
Published: November 2020

This protocol describes how to rear ambrosia beetles with the fungus of your choice. Could be used for just rearing beetles, or growing fungi on natural substrate. This protocol is part of the Bark Beetle Mycobiome (BBM) Research Coordination Network. For more information on the BBM international network: Hulcr J, Barnes I, De Beer ZW, Duong TA, Gazis R, Johnson AJ, Jusino MA, Kasson MT, Li Y, Lynch S, Mayers C, Musvuugwa T, Roets F, Seltmann KC, Six D, Vanderpool D, & Villari C. 2020. Bark beetle mycobiome: collaboratively defined research priorities on a widespread insect-fungus symbiosis. Symbiosis 81: 101–113 https://doi.org/10.1007/s13199-020-00686-9.
Testing For Cellulose Degradation v1
Authors: Hulcr Jiri
Published: November 2020

This protocol describes how to test for cellulose degradation using the congo red method. This protocol is part of the Bark Beetle Mycobiome (BBM) Research Coordination Network. For more information on the BBM international network: Hulcr J, Barnes I, De Beer ZW, Duong TA, Gazis R, Johnson AJ, Jusino MA, Kasson MT, Li Y, Lynch S, Mayers C, Musvuugwa T, Roets F, Seltmann KC, Six D, Vanderpool D, & Villari C. 2020. Bark beetle mycobiome: collaboratively defined research priorities on a widespread insect-fungus symbiosis. Symbiosis 81: 101–113 https://doi.org/10.1007/s13199-020-00686-9.
Importing live fungi to the US (UF Forest Entomology Lab) v1
Authors: F Gomez Demian , Li You , Hulcr Jiri
Published: November 2020

This protocol describes how to hand-carry live fungi through airport customs into the United States for the UF Forest Entomology Lab. This protocol is part of the Bark Beetle Mycobiome (BBM) Research Coordination Network. For more information on the BBM international network: Hulcr J, Barnes I, De Beer ZW, Duong TA, Gazis R, Johnson AJ, Jusino MA, Kasson MT, Li Y, Lynch S, Mayers C, Musvuugwa T, Roets F, Seltmann KC, Six D, Vanderpool D, & Villari C. 2020. Bark beetle mycobiome: collaboratively defined research priorities on a widespread insect-fungus symbiosis. Symbiosis 81: 101–113 https://doi.org/10.1007/s13199-020-00686-9.
Visualization of chitin-rich tissues with Lactophenol blue slide mount v1
Authors: Hulcr Jiri
Published: November 2020

This protocol describes how to visualize chitin-rich tissues, such as fungal mycelium. This protocol is part of the Bark Beetle Mycobiome (BBM) Research Coordination Network. For more information on the BBM international network: Hulcr J, Barnes I, De Beer ZW, Duong TA, Gazis R, Johnson AJ, Jusino MA, Kasson MT, Li Y, Lynch S, Mayers C, Musvuugwa T, Roets F, Seltmann KC, Six D, Vanderpool D, & Villari C. 2020. Bark beetle mycobiome: collaboratively defined research priorities on a widespread insect-fungus symbiosis. Symbiosis 81: 101–113 https://doi.org/10.1007/s13199-020-00686-9.
Perspectivas estudiantiles sobre la educación física en dos instituciones educativas públicas de secundaria en Lima, Perú
Authors: Dammert Martin , Guerrero Monica
Published: November 2020

El Currículo Nacional de Educación Básica del Perú subraya los beneficios de la Educación Física para el desarrollo integral estudiantil. Específicamente, busca que los educandos desplieguen un estilo saludable y que se desenvuelvan utilizando eficientemente sus habilidades motrices. Si bien la normativa enfatiza una educación física de calidad, esta área curricular ha sido generalmente desatendida. En este estudio cualitativo se entrevistó a 24 estudiantes de cuarto de secundaria de 2 instituciones educativas de Lima (pública y emblemática) para explorar sus perspectivas sobre la Educación Física. Además, se entrevistó a 2 autoridades educativas y a 3 docentes de Educación Física. Los resultados sugieren que el curso es asociado a beneficios personales y sociales como el bienestar, la salud, la convivencia y la socialización. Se visibiliza también el potencial de conflictos interpersonales surgidos durante las clases como importantes oportunidades de aprendizaje, así como el rol crucial del docente de Educación Física.
Adherence to Secondary Prevention and Influential Factors in Individuals with Coronary Angioplasty
Authors: Henao López Vanesa , Triviño Vargas Zaider
Published: November 2020

Objective. To explore the relation between adherence to secondary prevention and factors that influence on said adherence in people with acute coronary syndrome, who underwent percutaneous coronary angioplasty in a clinic in Medellín.

Methods. Cross-sectional study on a random sample of 128 volunteer patients. A questionnaire was used for sociodemographic variables, the “Scale to measure therapeutic adherence for patients with chronic diseases, based on explicit behaviors” by Trujano, Vega, and Nava andthe “Instrument to evaluate adherence by patients according to influential cardiovascular risk factors” validated by Consuelo Ortiz.

Results. Socioeconomic factors influenced in very low manner on the adherence to secondary prevention; factors related with the therapy did so moderately and patient factors influenced in low manner. No relation was found between the health provider factor and said adherence.

Conclusion. Factors exist that influence in a lesser or higher measure on adherence to secondary prevention and which must be recognized in people with coronary angioplasty to designstrategies to improve this aspect of self-care.
Hacia una caracterización de los traductores e intérpretes en Colombia
Authors: Giraldo-Ortiz John Jairo , Clavijo-Olmos Sandra Bibiana , Malavert-Chávez Constanza , Salazar-Giraldo Bibiana , Sarmiento-Jaramillo Camilo
Published: November 2020

El objetivo principal de este estudio, de carácter exploratorio, metodología cuantitativa y enfoque descriptivo, fue realizar una caracterización de los traductores e intérpretes en Colombia. Se trata de un estudio que, junto con otros, servirá de base para que profesionales, agremiaciones y entidades gubernamentales tengan elementos para la definición de estrategias que les permitan a estos profesionales ser más competitivos en los contextos local y global. Para lo anterior, se contó con una muestra de 98 participantes de diferentes nacionalidades en el ejercicio de la profesión en Colombia, quienes respondieron una encuesta vía web. Entre los hallazgos se encuentran que la mayoría de quienes ejercen la profesión son mujeres, con edades entre 30 y 40 años, en modalidad de trabajo freelance, con residencia principalmente en Bogotá y Medellín, con formación superior en otras áreas de conocimiento, se dedican principalmente a la traducción científico-técnica, en su mayoría desconocen y por ende no aplican normas para el aseguramiento de la calidad de los servicios, y suelen desempeñar actividades complementarias como la docencia de traducción o lenguas extranjeras, la edición o la corrección de estilo. Estos hallazgos sugieren la necesidad de trabajar en la eliminación de por lo menos tres grandes riesgos que afectan localmente a la profesión, a saber: a) la escasa oferta de programas de profesionalización y formación continua; b) la baja cobertura del servicio, y c) la poca cultura de agremiación.
Factors Shaping EFL Preservice Teachers’ Identity Configuration
Authors: Buendía-Arias Ximena Paola , André-Arenas Andrea , Rosado-Mendinueta Nayibe del Rosario
Published: November 2020

Preservice EFL teachers face many challenges when developing their practicum. Such an experience shapes their identity and influences the teaching and learning processes. This descriptive case study is about preservice teachers’ identity formation and the factors that shaped their identity configurations during a practicum course offered at a state university in Colombia. Data, collected through interviews, reflective journals, and drawing-derived metaphors were analyzed using thematic analysis. The results identified participants’ value/belief system, personality traits, context, pedagogical decisions, reflective practice, and critical incidents as influential factors in their identity formation process. The findings also revealed that identity can be constructed through the intersection between the different experiences they go through during their practicum and their past and future trajectories. The study suggests that EFL teacher education programs should take explicit pedagogical actions to incorporate the identified factors in their curriculum. This could strengthen EFL preservice teachers’ identity configurations and prepare them better for their future teaching roles.
EnSenias: herramienta tecnológica para aprender, enseñar, mejorar y usar la lengua de signos panameña
Authors: Rodríguez-Fuentes Antonio , Alain Lineth , García García Francisco
Published: November 2020

La comunicación ha sido una constante en el progreso en la sociedad, y la tecnología se ha erigido, desde hace poco, en su vehículo de expansión. La comunidad sorda encuentra limitada su comunicación y requiere engranajes adicionales. Este estudio de diseño no experimental, descriptivo y de enfoque mixto se enfoca en EnSenias, una plataforma on-line para aprender, enseñar, mejorar y usar la lengua de signos panameña, con el fin de explorar su funcionalidad mediante la validación de la misma. El estudio se llevó a cabo en el Instituto Panameño de Habilitación Especial. Para llevarlo a cabo, se recogieron datos de doce grupos focales (57 participantes) y se realizó un análisis mixto. Los resultados del análisis demuestran que EnSenias es necesaria y adecuada para el aprendizaje de esta lengua, su accesibilidad es universal, es útil para aprender y enseñar vocabulario de signos panameños, y también sirve como diccionario y traductor elemental de dicha lengua. Su carácter accesible permite que ciudadanos sordos, hipoacúsicos, oyentes, ciegos, con baja visión, sordociegos y otros puedan conocer la lengua de signos.
Reseña: Translation and Paratexts
Authors: Correa-Larios Olivia
Published: November 2020

La noción de paratexto en los Estudios de Traducción ha estado presente en investigaciones y trabajos de índole práctico, pero también en reflexiones teóricas, que exploran cómo impacta en el proceso y en el producto de traducción la relación entre el texto y su entorno conformado por otros textos dentro o fuera de él o por aspectos materiales o inmateriales, es decir, tanto físicos como socioculturales que lo rodean. En Translation and Paratexts, Kathryn Batchelor propone un marco teórico a partir de una exploración terminológica que conjunta la reflexión crítica con revisiones metodológicas del concepto de paratexto en investigaciones previas.
THE SIMULATION STRUCTURE OF THE HISTORICAL AND MYTHOLOGICAL TYPES IN FANTASY MMORPG
Authors: Pilkevych Pilkevych
Published: November 2020

The article deals with the reception of historical and mythological heritage in the video games of fantasy genre. The paradigms of object-oriented programming and MMORPG algorithm logic determine the structure of the content simulation. Сreating thousands of similar objects provides for top priority the provision of a single interface to entities of different types. Mythological content class upon another class, retaining similar implementation combines the principles of historical reception and programming inheritance.
IUS Acceptance Failure Data Base
Authors: McDaniel Herbert , Hopkins Laurence
Published: November 2020

This paper describes the failure data base obtained in component and vehicle level acceptance tests of the Inertial Upper Stage (IUS). Failure trends are presented as a function of test environment, failure classification, and testing sequence for eight flight vehicles.
A Review of Contamination Issues Associated with an Orbiting Space Station External Environment
Authors: Smith Alphonso
Published: November 2020

Contamination monitoring must be placed in the forefront for long-term space exploration experiments in order to help obtain interpretable data. Present day computer program codes have been developed to the stage where they are very useful for contamination modeling and have been used to some extent with the Shuttle Orbiter associated experimental programs. With the upcoming Space Station program, contamination issues must be openly discussed and put into the proper perspective in order to help alleviate some of the associated problems encountered during the Shuttle flight experiments.

Issues are discussed relative to ongoing contamination concerns, pointing out some errors of the past and suggesting improvements in experimental approaches to enhance the interpretability of data. The purpose of this article is to focus attention on a critical technology that has been ignored to some extent in past flight experiments. Also, references and data are presented to show that significant efforts have been made in the contamination area. The present need is to make use of the available data and ensure that contamination control guidelines are adhered to. This must be done early in any proposed orbiting spacecraft design and not be added in during critical experimental stages.
Carbon Dioxide and the Environment: A Problem of Uncertainty
Authors: Lemons John
Published: November 2020

The combustion of fossil fuels increases atmospheric levels of carbon dioxide. This may cause a long-term warming of the atmosphere. Solutions to the carbon dioxide problem are particularly difficult because adverse effects will be felt by future generations, but remedial action and sacrifices must be made by present generations. Decisions regarding the problem which affect both the immediate and long-range future must be made deliberately or by default in perhaps only 15-20 years, before we are reasonably confident with our knowledge of the problem and before we know whether it will, in fact, occur. Much of the uncertainty involves projections of future energy use, and scientific knowledge of the carbon cycle and the environment.
Corrosion Testing of Captor Strongback Bands
Authors: Prettyman Thomas
Published: November 2020

Accelerated corrosion tests were conducted by the Naval Surface Weapons Center on CAPTOR mine strongback bands. Strongback bands are part of the CAPTOR suspension system, which interfaces the mine to the delivery system of minelaying aircraft and surface ships. The laboratory tests were performed to recreate the stress corrosion cracking failures observed in CAPTOR stockpile storage. The tests were designed to produce the same failures during weeks of laboratory testing which occurred after several years of stockpile storage. This magnitude of accelerated testing required the use of aggressive corrosion test environments.

Eight strongback bands, representing (known) problem bands (H925 heat treated 17-4PH stainless steel), the present-use bands (H1015 heat treated 17-4PH stainless steel), and the proposed replacement bands (Inconel 718), underwent side-by-side testing. Both (known) problem bands failed by stress corrosion cracking: the first during 28-day temperature and humidity testing, and the second during the subsequent 1000-hour salt spray test. None of the three present-use or three proposed replacement bands failed through the temperature and humidity test, salt spray test, and twelve months of outdoor exposure. These failures indicate that the test environments are sufficiently aggressive to recreate fleet-observed stress corrosion cracking failures, but in a much shorter time.
Vacuum Baking of Shuttle/Centaur Components
Authors: Weingartner C.
Published: November 2020

A variation of the Centaur launch vehicle will be used as a high-performance upper stage to launch spacecraft from the Space Shuttle cargo bay into geosynchronous orbit. As an element of the Shuttle payload, Centaur must be designed to avoid contaminating sensitive spacecraft surfaces. Nonmetallic materials used in structural and electronic applications can exhibit high rates of outgassing in a space vacuum and contaminate critical spacecraft surfaces of varying temperatures as condensation occurs. Judicious material selection, per NASA specifications, is used to control instances of such contamination. Vacuum baking is permitted by NASA Specification SP-R-0022 to "bake out" potential sources of organic contamination. Most Shuttle/Centaur missions are planned for spacecraft having surfaces of various temperatures in locations that are susceptible to condensation of organic outgassing products. To determine the extent of potential contamination, General Dynamics has initiated a test program with the White Sands Test Facility that is designed to measure outgassing and condensation rates of nonmetallic components in their use configuration. This paper reviews the tests, equipment requirements, sensor instrumentation, and some of the results to date.
A Status Report Relative to a Standardized Test Method for Electrostatic Discharge (ESD)
Authors: Hoolihan Daniel
Published: November 2020

This report addresses the problems associated with developing a standardized test method for ESD. It does not delve into the multitudinous problems of ESD damage to computer chips. It does develop a background on ESD and its effects on electronic hardware.
Advantages of Facilities Monitoring System in Integrated Circuit Fabrication
Authors: Ligtenberg Allart
Published: November 2020

This paper discusses a computerized Facilities Monitor and Control System, which has been in use for several years at Hewlett Packard's Cupertino Integrated Circuit Division. Over 350 transducers monitor the IC fabrication support systems such as deionized (DI) water, process gases, process environment, cleanroom equipment and environment, as well as systems which ensure industrial hygiene, safety and environmental compliance. Examples illustrate how the Facilities Monitor System information has been used to improve yield, diagnose process control problems, prevent contamination and improve the facilities, resulting in significant cost savings. This is accomplished by continuous real-time monitoring, historical data acquisition and analysis, trendlining, correlation studies and various levels of alarm notification.
Aerosol Charging and Neutralization and Electrostatic Discharge in Clean Rooms
Authors: Liu Benjamin , Pui David , Kinstley Warren , Fisher Wayne
Published: November 2020

This paper describes the role of electrical charge on particle transport and deposition and the neutralization of particle electrostatic charge by ionized air. The level of electrical charge on airborne particles and the rate of charge neutralization by bipolar ions have been reviewed and the effect of charge on particle deposition on semiconductor waters discussed. Finally, the use of high voltage ionizers for electrostatic control in clean rooms is discussed.
Surface Contamination Monitoring by the Measurement of Scattering Distribution Functions
Authors: Carosso Paolo , Pugel Carosso Nancy
Published: November 2020

This paper describes the use of Bidirectional Scattering Distribution Functions (BSDF) to quantify surface degradation, thus providing an effective method for contamination monitoring.

This approach to contamination monitoring is based on the use of witness surfaces (mirrors or glass slides) located next to the critical surfaces. Contaminant accretion can be monitored during all phases of spacecraft fabrication, assembly, and testing. The method can be applied in other areas of contamination control such as monitoring of clean room environments. The BSDF can also prove extremely useful in establishing contamination control requirements and acceptability criteria. This paper describes the apparatus adopted to perform BSDF measurements and discusses some practical aspects of data collection. The results obtained in contamination monitoring programs performed at the NASA Goddard Space Flight Center are presented. Some possible new applications of this monitoring technique are also addressed.
ESS at Final Assembly Level Actual Results—Optimization Method
Authors: Géniaux Bernard
Published: November 2020

For nonrepairable devices, it is possible to evaluate and optimize Environmental Stress Screening (ESS) effectiveness using the well-known Weibull analysis techniques. For repairable modules or systems, these techniques cannot be applied directly; the equipment may involve more than one failure, and after each repair, during the early life period, its behavior changes (improves). From a statistical point of view, it is a mistake to consider all the failures in the aggregate. We should study separately the distribution laws of the first failure, the second failure, the third failure, etc. A comparison of these laws gives the average number of early failures per module or system. The knowledge of the distributions parameters yields the optimal screening duration. From this information we can easily define the optimal ESS process. This article reports how this method was actually used on a real case. Moreover, it demonstrates ESS effectiveness at the final assembly level, although the boards, equipped with high-reliability components, were already screened.
Calibrations Requirements and Methods for Liquid-Borne Particle Counters
Authors: Lieberman Alvin
Published: November 2020

This paper describes present U.S. practices for calibrating optical liquid-borne particle counters (APCs). Operation of these instruments is described briefly for both light extinction and scattering instruments in order to help the reader understand why empirical calibration is necessary. Calibration requirements are pointed out in terms of the need to verify both particle sizing and particle counting accuracy. Two calibration methods are currently used in the U.S. One is based on size and count response to a suspension of presized isotropic latex spheres. The other is based on APC adjustment to match the stated size distribution of a test dust polydisperse suspension at a specific concentration. Both methods are described and some advantages and problems are presented.
Great Lakes Shore Erosion
Authors: Wysockey Michael
Published: November 2020

This paper presents the problem of high water levels that cause increased shore erosion in the Great Lakes. It will describe the pertinent hydrology and coastal morphology of the area and the three fundamental solution strategies being pursued—lake level reductions, shore stabilization measures, and legal building restrictions. The effectiveness of these strategies is discussed.
Statistical Analysis Relating to Recent Federal Standard 209 (Cleanrooms) Revisions
Authors: Cooper Douglas
Published: November 2020

The recent revisions of Federal Standard 209 regarding clean-rooms include two statistical tests for the concentration data obtained from sampling airborne particles: a) that none of the location averages exceeds the Class Limit (CL) and b) that there be 95 percent confidence that the true mean of the location averages does not exceed the CL, based on the data making up the grand mean of averages. For sampling from a constant and uniform concentration (Poisson data) or from a concentration giving data that are normally distributed, we show the statistical implications of choosing a certain level of confidence that no location average exceed CL. Similarly, we show the statistical implications of the 95 percent confidence requirement on the grand mean. For any situation where each location has approximately the same standard deviation in its readings, the Poisson and normal distributions included, if one has 95 percent confidence that none of the locations exceeds the CL, the requirement for the grand mean is also likely to be met if five or more locations are sampled. Simulation methods can assist prediction, and several methods are summarized. The likelihood of meeting the standard can usually be improved by: reducing the average concentration and the variability of the concentration (through design and good practices), increasing the number of samples per location and the volume sampled for each, and keeping the number of locations sampled to the minimum allowed.
Rationale for Proposed Revisions to Federal Standard 209B (Cleanrooms)
Authors: Cooper Douglas
Published: November 2020

This paper discusses the rationale behind the proposed revisions of Federal Standard 209B on cleanroom air cleanliness classifications. The proposed revisions were developed in a series of meetings held by the RP-50 committee of the Institute of Environmental Sciences. The major recommended changes are:

1. Class 1 and Class 10 be added

2. The two proposed new classes may be met at particle diameters of 0.1,0.2,0.3, and 0.5 μm, (microns), and Class 100 may be met at 0.2,0.3 μm as well as 0.5 μm, with suitable adjustments in the required concentrations

3. Other classes (e.g., Class 50) be defined as appropriate

4. The number of sampling points be specified differently, and a distinction be drawn between unidirectional and non-unidirectional flow, rather than laminar and turbulent flow

5. Minimum sampling volumes be set, based on measurement errors

6. Verification be done initially and periodically

7. Verification require particle counting

8. Particle counting instruments require periodic calibration

9. An area be deemed to meet the class limit if both:

a) the average particle count at each location meets the class limit and

b) the mean of these averages is sufficiently below the class limit that the population mean is almost certainly (95% confidence level) less than the class limit

The rationale for these proposed changes is discussed.
Low Cost Thermal Vacuum Testing Facility for Electronic Units
Authors: Dgany Elhanan , Kochavi Eytan , Gruntman Shimon , Kinan Asher
Published: November 2020

A thermal vacuum testing facility for electronic units has been specified, designed, and built. It is fully operational and performs its tasks—thermal vacuum qualification and acceptance testing of electronic units.

All performance requirements and design details have been carefully evaluated on a cost-effective basis, resulting in achieving the design goal of low price (purchase, operation, and maintenance) together with ease of operation, maintenance simplicity, and upgrading options.

The major cost saving originated from a detailed analysis of thermal vacuum requirements that resulted in low cost substitutes to the common thermal shroud, together with a thermal plate. The plate is actively thermally controlled by a circulating fluid that is temperature regulated by a commercial heating and cooling unit.

The high vacuum pumping system includes a diffusion pump with backstreaming holders.
The Effectiveness of Satellite Environmental Acceptance Tests
Authors: Hamberg Otto , Tosney William
Published: November 2020

This article discusses the effectiveness of system level environmental tests conducted on satellites in reducing failures that could occur in early flight, and relates the flight failures potentially avoided to the types of test and the time expended. The results indicate that environmental testing of satellites reduces early flight failures appreciably. The information compiled and analyzed allows cost-benefit correlations of environmental tests for more effective future test planning.
A Fluid Dynamics Study of Microcontaminant Particle Removal from Silicon Waters
Authors: Busnaina Ahmed , Edler Janice , Gale Glenn , Kern Frederick
Published: November 2020

Particle removal using deionized clean water and centrifugal force (water rinsing) is an effective and commonly used method in the semiconductor industry. Understanding the flow field around the rotating waters is essential in determining the effectiveness and efficiency of the process. In this study, flow visualization is used to observe the jet trajectory and the flow pattern for different flow rates at different rotational speeds. The qualitative and quantitative results show that the rotating disk is completely covered with a water film only at certain values of the governing parameters. The second part of the study involves studying the shielding effect of the carrier on the flow pattern on the waters. The flow cannot be visualized or seen through the shielding. The flow pattern is therefore visualized with the aid of some chemicals (that react and leave a color pattern) on the surface of the water and in the water jet.
Integration of Numerical Simulation and Flow Visualization in the Design of Equipment for the Manufacture of Submicron Semiconductor Devices
Authors: Kern Frederick
Published: November 2020

Improved room and equipment aerodynamics can have a significant impact on the ability to obtain acceptable yields on high density semiconductor products.1 Goals for the equipment engineer/vendor are presented here, a set of design guidelines is established, and a design and test regimen formulated to achieve aerodynamically acceptable equipment designs is proposed.
Measuring Face Mask Performance: A Real Test
Authors: Friedrichs William
Published: November 2020

A cleanroom face mask or facial covering must be capable of efficiently filtering particles that range from 0.1 microns to over 20 microns in order to significantly control particles produced by the human respiratory system of a cleanroom worker. In addition to particle filtration efficiency, there are several other important face mask performance criteria that impact the overall effectiveness of a cleanroom mask. This article reviews the evolution of the cleanroom face mask and the test methods for measuring filtration efficiency. Performance criteria and test methods for measuring cleanroom face mask performance are recommended.
Experimental Results of the IES Modal Plate
Authors: Gregory Dan , Smallwood David
Published: November 2020

Studies show that a rectangular plate is a useful modal structure that can be used for several purposes, such as comparing various modal systems and modal extraction algorithms, comparing test techniques, and training new personnel in these tasks. Plates roughly 53 cm x 32 cm x 2 cm (21 in. x 13 in. x 0.8 in.) were constructed by several participants from polymethyl methacrylate. The plates were then tested by the participants and the results compared with a NASTRAN analysis. The results show about 25 useful modes in the plate between 160 and 2500 Hz. The plate has a variable modal distribution with widely separated modes easily identified to very closely coupled modes quite difficult to separate. With careful experiments, the modal frequencies of the plate can be reproduced within 2 percent of the predicted values, and the mode shapes can be reproduced with errors of 20 percent or less. Less careful experiments can lead to large errors in frequencies, mode shapes, missed modes, and mixed modes.
Reliability Improvement of Power Inverters Through Environmental Stress Simulation
Authors: Delmont Michael , Welby Stephen
Published: November 2020

This article presents a case study of the use of environmental stress simulation to qualify commercially developed items to stricter military reliability requirements. The system offered as an example is the static inverter adapted for use by the AN/TLQ-17A(V)3 Traffic Jam system.
Replacing Chlorofluorocarbons in Industry
Authors: Weigel Kurt
Published: November 2020

Scientific evidence indicates that ozone depletion over the South Pole is more serious than was suspected a few years ago. As a result, production of the principal ozone-depleting compounds is scheduled to be phased out over the next decade. The impact of the elimination of these chemicals on industries will be immediate and significant, with the aerospace and electronics industries among the most severely affected. Alternative solvents, refrigerants, and foam-blowing agents are being developed, but will not be available in commercial quantities until 1992 at the earliest. Meanwhile, CFC users are working with the chemical manufacturers, EPA, DoD, and various research organizations, to speed up the process of identifying and implementing alternative compounds or processes. Most of the proposed alternatives have some drawbacks when compared with CFCs, but can be implemented safely if the user takes the time to understand the issues thoroughly and involves all affected parties in the decision-making process.
Comparing Three Environmental Particle Size Distributions: Power Law (FED-STD-209D), Lognormal, Approximate Lognormal (MIL-STD-1246B)
Authors: Cooper Douglas
Published: November 2020

Particle size strongly influences particle behavior. To summarize the distribution of particle sizes, a distribution function can be used. The characteristics of the particle size distributions chosen are important for two specification documents currently under revision: (1) FED-STD-209D, concerning air-cleanliness in manufacturing, which uses cumulative particle size distributions that are linear when plotted on log-log axes; these are power law distributions. (2) MIL-STD-1246B, "Product Cleanliness Levels and Contamination Control Programs," primarily concerning surface cleanliness, which uses cumulative particle size distributions that are linear when plotted as the logarithm of the cumulative distribution versus the square of the logarithm of the particle size, log2x, A third distribution, the lognormal, is commonly found in aerosol science, especially where there is a single particle source. The distributions are compared and discussed. The FED-STD-209D power law distribution can approximate a lognormal distribution over only a limited size range. The MIL-STD-1246B distribution is an asymptotic approximation to the lognormal distribution.
Test Facility Requirements for the Thermal Vacuum Thermal Balance Test of the Cosmic Background Explorer Observatory
Authors: Milam Laura
Published: November 2020

The cosmic background explorer observatory (COBE) underwent a thermal vacuum/thermal balance (TV/TB) test in the space environment simulator (SES) at the Space Simulation Test Laboratory, Goddard Space Flight Center. This was the largest and most complex test ever accomplished at this facility. The 4 × 4 m (13 × 13 ft) spacecraft weighed approximately 2223 kg (4900 lb) for the test. The test setup included simulator panels for the inboard solar array panels, simulator panels for the, flight cowlings, sun and earth sensor stimuli, thermal/radio frequency shield heater stimuli, and a cryopanel for thermal control in the attitude control system/shunt dissipator area. The fixturing also included a 4.3 m (14 ft) diameter gaseous helium cryopanel which provided a 20° Kelvin (K) (-253° C) environment for the calibration of one of the spacecraft's instruments, the differential microwave radiometer. This cryogenic panel caused extra contamination concerns so a special method was developed and written into the test procedure to prevent the high buildup of condensibles on the panel, which could have led to backstreaming of the thermal vacuum chamber. The test was completed successfully with a high-quality simulated space environment provided to the spacecraft. This paper describes the test requirements, test setup, special fixturing requirements, related contamination concerns, and a general discussion of the test and test results.
Vendor Process Contamination Checklist: A Diagnostic and Troubleshooting Tool
Authors: Nagarajan R.
Published: November 2020

Yield and reliability considerations have resulted in an increased emphasis on particulate and chemical contamination control for vended parts in the disk drive industry as well as in other microelectronics and precision manufacturing industries. A vendor process contamination checklist (VPCC) intended primarily to assist the responsible engineer in identifying potential sources of contamination within the vendor process is discussed. Appropriate remedial action may then be initiated in consultation with a cleaning/contamination control specialist. The questionnaire is slanted toward machining houses because these environments are notoriously difficult to diagnose and control with respect to contamination. It has been used with considerable success at IBM San Jose for vendor process investigation and rectification and has often resulted in greatly enhanced cleanliness of incoming components. The description of the checklist is followed by a discussion section where the reasons for some of the less obvious questions are stated. Examples of process improvements obtained by using the checklist are presented.
Comments on Kurtosis of Military Vehicle Vibration Data
Authors: Connon William
Published: November 2020

Road vibration tests were recently conducted on a series of shelters on dolly sets and on a series of prototype trucks at the U.S. Army Combat Systems Test Activity (USACSTA) at Aberdeen Proving Ground. Data from histogram or amplitude distribution tables were plotted in the normal probability domain to provide a graphic representation. When examining these probability plot data, a divergence of the actual distribution from the normal distribution at the tails was noticed. Of the 104 trials compared, the normal distribution was exceeded by 30 trials at the 90 percent level, 87 trials at the 99 percent level, and 88 trials at the 99.9 percent level. This indicates that the actual measured values at the extreme ends of the distribution (beyond the 90 percent occurrence levels) are larger in magnitude (acceleration) than would be predicted by the assumption of a normal distribution.

This same trend was noticed during examination of the kurtosis values for the same data sets. The values generally exceeded a value of three, which is the expected value for a Gaussian distribution. Because the kurtosis is largely affected by data values far from the mean, a correlation between the normalized 99.9 percent values and the normalized kurtosis values was tried. A linear regression line was fit through the data, which produced a correlation of approximately 0.82.

Although no formal effort has been put forth to catalog kurtosis measurements from military vehicles, it has generally been observed that the kurtosis values obtained from operation over our test courses is greater than three, indicating that the tails of a vibration distribution from operation over severe terrain are further from the mean (larger amplitude) than would be predicted from a normal distribution. If the kurtosis of the laboratory test distribution is less than that of the field distribution, the extreme values seen in the field environment will not be duplicated in the lab. The addition of conservatism during the schedule development process should be enough to overcome this difference; however, dome effort should be made to develop a "bi-domain" (frequency and time domain amplitude) control system so that the amplitude distribution of the lab test will more closely match that of the field data from which the schedule was derived.
Selecting a Cost-Effective Number of Samples To Use at Preselected Locations
Authors: Grotzinger Stephen , Cooper Douglas
Published: November 2020

In the control of environmental contaminants, it is often useful to sample at preselected locations to determine concentrations and their means. These locations might be on a surface, throughout a room, or outdoors. Applications include air and water pollution control, industrial hygiene, and contamination control in industry. Contamination is a major cause of yield and reliability losses in the microelectronics industry. Sampling the cleanroom environment or sampling the product surfaces can help diagnose and prevent contamination problems, but sampling is becoming increasingly expensive. One wants to use sampling resources effectively to achieve desired low levels of uncertainly. We assume that the locations to be sampled have been selected, perhaps as described by Cooper et al. We show how to calculate the optimal number of samples to be taken at each location so as to minimize the uncertainty in the mean over the entire region under study, subject to a cost constraint. We consider two distinet criteria for measuring this uncertainty. We also address the optimal allocation for minimizing the cost, subject to an upper bound on the standard error. We also discuss the differences between these approximate solutions and the true solutions, which are integers.
Precision Cleaning in a Production Environment with High-Pressure Water
Authors: Nagarajan R. , Welker R.
Published: November 2020

The increasing contamination control requirements for disk drives, and the prevailing mandate to climinate chlorinated solvents in cleaning applications have allowed high-pressure water spray to emerge as an effective and environmentally sound method for cleaning. Certain substrates, such as machined metals and alloys, can be cleaned using high-pressure water to state-of-the-art cleanliness levels. Following developmental investigations in the laboratory, two cleaners utilizing high-pressure (up to 3000 psig), high-flow (up to 50 gpm) water have been procured for use at suppliers of critical disk-drive components. Acceptance-runoff, certification, and production-run cleanliness data pertaining two the two high-pressure cleaners are presented here in terms of liquid-born particle counts on contaminants extracted from substrates ultrasonically, or by means of a low-pressure water spray. Results indicate that residual particulate contamination levels on high-pressure sprayed parts may be lower by more than two orders of magnitude compared with those obtained by more conventional cleaning methods. The cleaning efficiency increases significantly with particle size. The importance of nozzle manifold design and placement, for both cleaning and drying, is demonstrated quantitatively with examples of the deleterious consequences of not optimizing them. The underlying cleaning mechanism is explained briefly. Potential advantages and disadvantages associated with high-pressure water spray cleaning are fully discussed, and recommendations are offered for utilizing this technology most effectively.
Application of Six Sigma Statistical Quality Control to Monitoring the Deposition of Contaminating Particles
Authors: Cooper Douglas , Babcock Jan , DiPietro Frances
Published: November 2020

The goal of this work was to help in the control of particle deposition in manufacturing cleanrooms by the application of statistical quality control methods, specifically for the Class 1 cleanroom at the Semiconductor Research and Development Center at IBM East Fishkill. Each week a set of silicon wafers was inspected and the number of particles present were recorded ("precount"). The wafers were then put in various locations throughout the cleanroom. The wafers were left exposed to cleanroom air for one week, and then the number of particles were determined again. The quality control approach was the "Six Sigma" system developed originally by Motorola, Inc. In another paper, we described how these measurements were put into a Six Sigma framework: upper specification limit, target level, and estimates of the standard deviations.1 Here, we present results from 30 weeks of measurements and discuss the choice of assumed measurement distribution function (for example, the normal versus the lognormal distribution). Some locations had lognormal count frequency distributions. Others had count distributions with normal distribution components or with unclassified distribution components. Values of skewness and kurtosis were almost all greater than what would be expected from a normal distribution. In particular, this means that larger percentages were outside the limits μ±κs than would be true for a normal distribution, so that predictions of percentages of nonconforming instances would be erroneously low if the normal distribution were assumed.
Guidelines for Dynamic Data Acquisition and Analysis
Authors: Piersol Allan
Published: November 2020

The structural responses produced by the operation of pyrotechnic devices (commonly called pyroshocks) constitute one of the most difficult types of dynamic data to accurately measure and analyze. For this reason, a separate appendix devoted solely to pyrochock data acquisition and analysis problems has been included in a proposed military handbook on Guidelines for Dynamic Data Acquisition and Analysis. This paper summarizes the recommendations concerning pyroshock data given in the final draft of that proposed military handbook.
Lessons Learned from Modal Testing of Aerospace Structures
Authors: Hunt David , Brillhart Ralph
Published: November 2020

A wide variety of challenges have been encountered during the past 10 years of aerospace modal testing. New excitation methods have evolved, including single and multiple input random. Enhancements to traditional single and multiple input sine methods have been developed. Data analysis techniques that allow more consistent modal models to be extracted in less time than previously required have also been developed. New data acquisition hardware allows more rapid acquisition of modal data. As a result of these new excitation methods, data acquisition hardware and analysis tools, more high-quality data can be collected in considerably less time than was possible in the past. Modal surveys with 200 to 400 channels of response are becoming more commonplace. During the development and implementation of these new capabilities, many lessons have been learned about how to manage the increased amount of data collected and how to ensure that the quality remains high.
Nonlinear Aspects of Shock Response in Isolated Accelerometers
Authors: Paez Thomas , Hunter Norman
Published: November 2020

Numerous investigators have studied the potential for chaotic vibrations of nonlinear systems. It has been shown for many simple nonlinear systems that when they are excited severely enough, or with the appropriate parametric combinations, they will execute chaotic vibrations. The present investigation considers the potential for the occurrence of chaos in a practical nonlinear system—the isolated accelerometer. A simple first-order model is proposed for the isolated accelerometer. It is shown that chaos can occur in the isolated accelerometer. A preliminary investigation into the bearing that this chaos potential has on the measurement of shock response is summarized.
The TRW Thermal Insulation Process Continuous Process Improvement in Work
Authors: Steimer Carlos
Published: November 2020

This paper describes the Total Quality Management Continuous Process Improvement concept as applied to a specific cost-reduction project. The use of CPI to successfully reduce formal documentation costs and organizational complexity in the development of spacecraft multilayer insulation blankets is described. General CPI principles and guidance are also provided.
Optimizing Polysilicon Deposition for Film Uniformity and Particles
Authors: DePinto Gary
Published: November 2020

This paper describes a three-step approach to characterize a low-pressure chemical vapor deposition (LPCVD) flat polysilicon process. The first step was to design and construct a flat polysilicon deposition furnace for reduced defectivity and improved film uniformity. The second phase was to characterize a process in this newly constructed furnace for both film uniformity and particles by using an L18 Taguchi experimental design. The third phase was to verify the recommended setting from the experimental design by processing confirmation runs. Results from the confirmation runs in the optimally constructed polysilicon furnace showed that particles can be reduced by up to 66 percent, and film uniformity can be improved by 29 percent over the current production process.