bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimation of burned areas in forest fires using artificial neural networks
Authors: Calp M. Hanefi , Kose Utku
Published: November 2020

Introduction: This article is the product of the research “Developing an Artificial Neural Network Based Model for Estimating Burned Areas in Forest Fires”, developed at Karadeniz Technical University in the year 2020.

Problem: Forest Fires are an issue that greatly affect human life and the ecological order, leaving long-term issues. It should be estimated because it is not known when, where and how much the fire will be in the area.

Objective: The objective of the research is to use artificial neural networks to estimate the burned areas in forest fires.

Methodology: A feed-forward backpropagation neural network model was used for estimating the burned areas.

Results: We performed a performance evaluation over the proposed model by considering Regression values, Mean Absolute Percentage Error (MAPE) and Mean Square Error (MSE). The results show that the model is efficient in terms of its estimation of burnt areas.

Conclusions: The proposed artificial neural network model has low error rate and high estimation accuracy. It is more effective than traditional methods for estimating burned areas in forests.

Originality: To the best of our knowledge, this is the first time that this real, unique data has been used for building and testing the model’s estimations and the improvements that have been made in producing results faster and more accurately than with traditional methods.

Limitations: Since there are regional differences over different forest areas, effective criteria need to be analysed regarding the target regions.
Understanding the Structure of Tourism Experience in Autobiographical Memory
Authors:   The Tourism Sciences Society Of Korea, Han Seok-Ho , Yoon Ji-Hwan
Published: November 2020

The purpose of this study was to identify the common and connotation structure of the autobiographical memory formed by tourism experience. Based on Colaizzi’s phenomenological method, the contents of common autobiographical memories in the retrospective of tourism experience was summarized in an intensive structure. Specifically, the autobiographical memory in the pre-trip stage was structured into three categories('Travel planning', 'Self-directed planning', and 'Expectation and anxiety'). The on-site stage was structured into a single category(‘Unusual experiences’). Lastly, the post-trip stage’s autobiographical memory was structured into three categories(‘Discovering new meanings’, ‘Positively distorted emotions’, and ‘Savoring memories’). The tourism experience shown in autobiographical memory is derived from experiences that have given subjective meanings according to cognitive and affective self-consciousness. It may include past experience or unconsciously, automatically, or reflexively by certain external conditions or stimulation. In particular, prior knowledge and external stimulation accumulated from past experience acted as crucial influence factors of tourist behavior and decision-making, and the process of such selection was also a part of the autobiographical memory. It was also identified that the autobiographical memory could be reconstructed and distorted by various factors. Our findings may help researchers and practitioners understanding the decision-making mechanism in tourist autobiographical memory, and devise various theoretical and practical strategies for evoking and promoting memory.
Agricultural trichothecene mycotoxin contamination affects the life-history and reduced glutathione content of Folsomia candida Willem (Collembola)
Authors: Szabó Borbála , Bálint Benjamin , Mézes Miklós , Balogh Krisztián
Published: November 2020

There is limited data available concerning the effect of T-2/HT-2 toxin or deoxynivalenol (DON) on invertebrates such as springtails, and no data on their life history and oxidative stress. Control maize and DON or T-2 toxin contaminated maize were fed to Folsomia candida with a toxin content of 16324 mg DON kg–1 or 671 mg T-2 kg–1 maize. Ten to twelve days old animals were investigated in a life-history test and a stress protein test.T-2 toxin did not affect Folsomia candida in any measured parameters. The DON exposed group showed decreased growth and reproduction, and a higher survival rate. DON treatment resulted in lower protein content, while reduced glutathione content was higher than in control. It suggests that DON activated the glutathione-related detoxification pathway, which possibly causes a higher survival rate. The results also suggest that the oral toxicity of DON or T-2 is lower than through physical contact.For that reason, DON and T-2 toxin contaminated maize is not suggested to be used as green manure in the native state. Alternative solutions could be using mycotoxin contaminated maize for biogas production, or after decontamination by bacterial strains, it can be used as organic fertilizer.
Estudo sobre a criação de vínculos afetivos por professores da modalidade EAD
Authors: Imperatore Simone , Soares Echeveste Simone
Published: November 2020

A modalidade de Educação a Distância (EaD) tem merecido destaque nas publicações relacionadas à educação devido aos novos cenários e papéis assumidos por professores e alunos. Os desafios metodológicos são inúmeros; as teorias constroem-se em alicerces constituídos de aprendizagem colaborativa, oferecendo autonomia ao aluno e ao professor. Diante de toda esta mudança de paradigmas que a EaD traz no processo de aprendizagem, um dos aspectos mais relevantes para seu sucesso são as relações entre professores e alunos em um ambiente virtual e como se determina a criação de vínculos indispensáveis nesse processo. O presente estudo teve como objetivo identificar o uso de ações e procedimentos metodológicos que pudessem ser realizados pelos professores da modalidade EaD para a criação de vínculos afetivos com seus alunos, observando de que forma os professores conduzem suas disciplinas com o propósito de fomentar uma relação mediadora que valoriza as dimensões humanas fundamentais. Caracterizou-se por uma pesquisa quantitativa, realizada com uma amostra de 85 professores universitários que atuavam na modalidade 100% a distância, através de um questionário estruturado. Dentre os principais resultados obtidos, destacam-se que 54,1% dos professores investigados atuavam a mais de 9 anos na EaD e 70,6% possuíam alguma formação específica para lecionarem na modalidade a distância. Observou-se que a comunicação entre professor/aluno foi a dimensão que mais precisava de atenção, que os professores ainda enfrentavam barreiras devido a habilidades tecnológicas e pessoais para a comunicação através de áudio e vídeos, e que o professor que já tinha a experiência de ser um aluno EaD favorecia uma maior afetividade no desenvolvimento de suas aulas. O estudo pode concluir que cabe ao professor repensar o seu papel nesse novo contexto, despir-se das metodologias convencionais utilizadas em suas aulas presenciais e assumir a posição de mediador no processo ensino-aprendizagem, traçando novas arquiteturas pedagógicas com vistas à criação de laços sociocognitivos, afetivos e emocionais, pois só assim este viabilizará a aprendizagem significativa de seus alunos.
A Case for Transnational Law in Contemporary Times
Authors: Soyapi Brewsters
Published: November 2020

When Jessup first wrote about transnational law about 60 years ago, scholarship on globalisation had not started yet. It seems though that transnational law, as we understand it, is as closely related to and has been developing alongside globalisation. However, transnational law and its place in scholarship remains contested. In the context of this contribution, globalisation serves as the catalyst that has transformed the manner in which law is viewed nationally and internationally and as such presents the lens through which transnationality could be understood and conceptualised. The article shows that the transnationalisation of law is inevitable in a fluid and ever-changing society which demands answers and solutions to the increasing problems brought about by and through globalisation.
Демографическая и семейная политика в разных странах: концептуальные подходы и практики
Authors: Исупова Ольга Генриховна
Published: November 2020

Статья посвящена анализу различных концептуальных подходов к семейной и демографической политике, начиная с периода формирования теоретических оснований воздействия государства на население в XIX веке. Исторически семейная политика выросла из демографической, и одновременно является поздним разделом политики социальной. Этим объясняется большое количество противоречий в ее идеологии в разных странах. В статье описана эволюция подходов к семейной политике в Европе и США с акцентом на развитии в конце XX века и в первые десятилетия — XXI (рождаемость и экономическое развитие, детское и женское образование, репродуктивные права, благосостояние различных возрастных и гендерных групп населения, баланс жизни и труда, реакция на падение рождаемости ниже уровня простого воспроизводства, этическое восприятие населением «навязывания» людям стандартов рождаемости и др.). Рассмотрены различные типологии систем семейной политики в развитых странах по разным основаниям — многообразие в этой области свидетельствует об отсутствии консенсуса и конвергенции, пока ни одна из национальных систем политики не может быть названа однозначно эффективной. Важным для определения идеологии семейной политики в настоящее время является то, обращена ли она к индивиду (и какому именно индивиду) или к семье как общности (и к какой именно форме/формам семьи), как каждая конкретная концепция решает вопрос о взаимодействии семьи и государства. На примере США показано, как представления о том, что в семейные дела лучше не вмешиваться, постепенно изменялись, появлялись не только отдельные политики, направленные на помощь семьям, но и стремление соответственно изменить законодательство. Всё больше стран, где семейная политика, скорее, идет за социальными изменениями вместо того, чтобы пытаться направить их в заранее заданное русло.
Центр-периферийные различия продолжительности жизни в России: региональный анализ
Authors: Щур Алексей Евгеньевич , Тимонин Сергей Андреевич
Published: November 2020

Высокий в сравнении со странами Запада уровень смертности и значительные пространственные различия в ожидаемой продолжительности жизни – серьезные вызовы, стоящие перед Россией. Решение задач повышения продолжительности жизни и улучшения здоровья россиян, в том числе за счет уменьшения неравенства в смертности как между субъектами РФ, так и на внутрирегиональном уровне, тесным образом переплетаются с целями пространственного развития России, направленными на сокращение межрегиональных различий в уровне и качестве жизни людей.

В статье представлена оценка различий в смертности между «центром» и «периферией» регионов и динамика этих различий в 67 регионах России, в которых проживает три четверти населения страны. Период исследования – 2003-2018 гг. – характеризуется устойчивым ростом ожидаемой продолжительности жизни при рождении в России. Используя данные Росстата по городам, мы оценили ожидаемую продолжительность жизни при рождении для 67 региональных центров и для остальной территории регионов («периферии»). В зависимости от величины различий и динамики их изменений были выделены 6 типов регионов (I-VI). Для регионов, в которых наблюдается наибольший центр-периферийный разрыв в ожидаемой продолжительности жизни, применен метод декомпозиции, позволивший определить ключевые возрастные группы и причины смерти, ответственные за столь высокие различия.

В 36 регионах России, отнесенных к I-III типам, центр-периферийный разрыв превышал среднероссийский уровень, при этом лишь в 6 из них в 2003-2018 гг. отмечалась тенденция к сокращению разрыва. Анализ результатов декомпозиции различий в продолжительности жизни для первых трех типов регионов показал, что у мужчин отставание периферии от центров обусловлено различиями в  смертности в трудоспособном возрасте от внешних причин смерти, особенно от ДТП, убийств и самоубийств, а также от «алкогольных» причин смерти, у женщин – различиями в смертности в пожилом возрасте от хронических неинфекционных заболеваний.

Несмотря на, казалось бы, «объективный» характер центр-периферийных различий в уровне смертности в России (преимущество центров в продолжительности жизни в первую очередь зависит от социально-демографических характеристик жителей, образовательной структуры населения, а также селективной миграции, направленной из периферии в центры), положительный опыт других стран показывает, что эффективная политика в области общественного здоровья может значительно сократить размах пространственного неравенства в уровне смертности даже при сохранении существенной гетерогенности в уровне социально-экономического развития территорий.
COVID-19: Threat or Opportunity?
Authors: Rivaz Mozhgan , Kazemi Seyed Mojtaba , Mosallanezhad Mina
Published: November 2020

The COVID-19 pandemic is spreading quickly. Despite scientists’ best efforts all over the world, there is not a vaccine or definite treatment for it and the novel coronavirus remains a threat to humanity with far-reaching, and in many cases, irredeemable consequences for the economic, political, social-psychological , and cultural aspects of humans’ lives.(1)The quick transmission and fatality of the disease, absence of herd immunity, lack of or inequitable distribution of resources, e.g. Personal Protective Equipment ( PPE), and the existing challenges in the implementation of social distancing result in a daily increase in the number of victims and, consequently, an ever-expanding workload in healthcare systems worldwide. Moreover, the increasing mortality and morbidity of COVID-19 and lack of hospital beds and ventilators have led to healthcare provider’s exhaustion and burnout.(1,2) Healthcare providers, especially nurses are the most vulnerable group in the face of the current disaster. Unfortunately, In the world, many front-line experts have lost their lives.(3)
Feelings, Stress, and Adaptation Strategies of Nurses against COVID-19 in Guayaquil
Authors: Franco Coffré Joicy Anabel , Leví Aguirre Patricia de los Ángeles
Published: November 2020

Objective. To explore the feelings, stress factors, and adaptation strategies of nurses during the COVID-19 pandemic in Guayaquil, Ecuador.

Methods. A cross-sectional, descriptive quantitative study, conducted through the application of a 52-item questionnaire with four sections (feelings, perceived stress, stress-reducing factors, and adaptation strategies). The study population was 227 nursing professionals from “Hospital General del Guasmo Sur” of the Ministry of Public Health, who worked during the peak of the pandemic from March to May 2020. The sample comprised 155 nurses who voluntarilyaccepted to participate. The study received 127 complete questionnaires for analysis.

Results. The data showed the priority of humanist feelings and professional duty for these nurses, mostly young (59% under 35 years of age and with the professional exercise of three and fewer years), against the fear of contagion and the stress of strenuous work. They also revealed the great importance for them of the institutional support, recognition to the staff, and strict organization of safe care, like strategies for coping with this difficult experience.

Conclusion. The COVID-19 pandemic represented for nurses from Guayaquil a great professional and emotional challenge. Health services and society could consider these findings to avoid burning out nurses and their professional desertion.
Subtitles in virtual reality: Guidelines for the integration of subtitles in 360º content
Authors: Agulló Belén , Matamala Anna
Published: November 2020

Immersive content has become a popular medium for storytelling. This type of content is typically accessed via a head-mounted visual display within which the viewer is located at the center of the action with the freedom to look around and explore the scene. The criteria for subtitle position for immersive media still need to be defined. Guiding mechanisms are necessary for circumstances in which the speakers are not visible and viewers, lacking an audio cue, require visual information to guide them through the virtual scene. The aim of this reception study is to compare different subtitling strategies: always-visible position to fixed-position and arrows to radar. To do this, feedback on preferences, immersion (using the ipq questionnaire) and head movements was gathered from 40 participants (20 hearing and 20 hard of hearing). Results show that always-visible subtitles with arrows are the preferred option. Always-visible and arrows achieved higher scores in the ipq questionnaire than fixed-position and radar. Head-movement patterns show that participants move more freely when the subtitles are always-visible than when they are in a fixed position, meaning that with always-visible subtitles the experience is more realistic, because the viewers do not feel constrained by the implementation of subtitles.
La lectura en voz alta en la formación inicial de los maestros de educación infantil de la Universidad de Cádiz
Authors: Trigo-Ibanez Ester , Rivera-Jurado Paula , Sánchez-Rodríguez Susana
Published: November 2020

El objetivo de esta investigación fue valorar la utilidad de una secuencia didáctica para mejorar la competencia en lectura literaria en voz alta de maestros de Educación Infantil en formación de la Universidad de Cádiz. En un marco de investigación-acción, se realizó un análisis de contenido de los datos generados en dicha implementación: listado de obras seleccionadas para la lectura, grabaciones en vídeo de las lecturas en voz alta, rúbricas para la coevaluación, foros de e-autoevaluación registrados en la plataforma del curso y un grupo focal de discusión. Los resultados mostraron que la implementación de la secuencia fue efectiva para permitir que el alumnado avanzara en su competencia lectora en voz alta. Además, posibilitó la compilación de un corpus de obras idóneas para la lectura en voz alta. Sin embargo, se detectaron carencias en relación con la selección de las obras y dificultades en la realización de la lectura para lograr la comprensión por parte del público. Se constata también la necesidad de integrar la formación lingüística y literaria en los programas de formación de maestros y el interés de utilizar la evaluación formativa para fomentar un aprendizaje reflexivo.
Instruction on Metaphors During a Study-Abroad Program: Students' Perceptions and Understandings
Authors: Tocaimaza-Hatch C. Cecilia
Published: November 2020

It has been observed that language learners struggle to gain access to the metaphorical structures that are part of the target language and culture. In this study, six Spanish L2 learners and nine Spanish heritage speakers from the United States completed a study abroad program in Spain in which language instruction was supplemented with a module on the subject of metaphors. This article seeks to describe this module and present learners’ perceptions of its implementation and of the learnings resulting from it, as reflected in learners’ weekly reflections and exit questionnaire. The analysis of these data indicated that most participants became aware of metaphors in every-day language. However, they were not fully able to produce metaphors themselves. Pedagogical implications of this experience include differentiated metaphor instruction for heritage speakers and L2 learners, and fostering not just metaphor awareness but competence.
Geleneksel veya Siber Zorbalığa Maruz Kalmanın Okula Yabancılaşmaya İlişkin Etkileri
Authors: HAN Ferhat , DEMİRTAŞ Hasan
Published: November 2020

Bu araştırmanın amacı öğrencilerinin okulda ve siber ortamda ne türde zorbalıklara maruz kaldıklarını ve zorbalığa maruz kalmanın okula yabancılaşmaya ilişkin etkilerini tespit etmektir. Araştırma da nitel araştırma desenlerinden olgu bilim deseni kullanılmıştır. Araştırmanın katılımcıları farklı okul türlerinde öğrenim gören 16 kadın 15 erkek olmak üzere toplam 31 lise öğrencisidir. Araştırma verileri daha önce en az bir defa geleneksel veya siber zorbalığa maruz kalmış gönüllü öğrencilerden yarı yapılandırılmış görüşme formu aracılığıyla toplanmıştır. Araştırma verileri betimsel analiz ve içerik analizi teknikleri kullanılarak analiz edilmiştir. Öğrencilerin görüşleri frekans ve yüzde değerleri kullanılarak sıralanmıştır. Araştırma sonunda öğrencilerin geleneksel zorbalık türlerinden en çok, alay etme, küfür, hakaret, hakkında söylenti çıkarılması, iftiraya uğrama, aşağılama, itilme ve dövülmekle tehdit edilme şeklinde zorbalıklara maruz kaldıkları tespit edilmiştir. Araştırmada iki öğrencinin de cinsel zorbalığa maruz kaldığı tespit edilmiştir. Siber zorbalık açısından öğrencilerin en çok, tehdit edildiği, küfür ve hakarete uğradığı, sahte hesaplardan gelen arkadaşlık istekleriyle rahatsız edildikleri tespit edilmiştir. Araştırma sonunda okul ortamında yaşanan bazı olumsuzlukların siber ortama, benzer şekilde siber ortamda yaşanan bazı olumsuzlukların da okul ortamına taşındığı görülmüştür. Geleneksel ve siber zorbalığa maruz kalmanın öğrencilerin psikolojilerini ve ders başarılarını olumsuz etkileyerek öğrencilerin güçsüzlük boyutunda okula yabancılaşmalarına neden olduğu görülmüştür. Bazı öğrencilerin zorbalarla kavga ederek kuralsızlık boyutunda okula yabancılaştıkları görülmüştür. Zorbalık mağduru bazı öğrencilerin okula gitmek istemedikleri, devamsızlık yaptıkları, insanlarla konuşma çekindikleri ve buna bağlı olarak sosyal uzaklık boyutunda okula yabancılaştıkları tespit edilmiştir.
IN THE FIELD OF HISTORICAL AND ARCHIVAL SCIENCES
Authors: Kotsur Нalyna
Published: November 2020

The article is devoted to the scientific activity of Professor Mykola Shcherbak, his contribution to the development of national historical science.
SELECTION CRITERIA FOR TECHNICAL DIAGNOSTIC SYSTEMS AND INFORMATION TRAINING OF MOTOR VEHICLES
Authors: Bansak O.V. , Tolok I.V. , Lapina E.V. , Martcenco A.M.
Published: November 2020

The aspects of the development of criteria for the selection tools and options for systems of technical diagnostics of vehicles are considered. Monitoring systems and forecasting the technical condition of vehicles will require expanding the range of monitored parameters. The above criteria for assessing the selection of the optimal set of measured parameters and their means of measurement to ensure the effectiveness of the developed systems monitoring and diagnostics. The main aspects of information preparation diagnostics and repair of motor vehicles are given.
The Measurement of Particle Sizes Below 0.1 Micrometers
Authors: Knollenberg Robert
Published: November 2020

The paper examines the size domain of particles below 0.3 μm with considerable emphasis on the 0.1 μm and below size range, encompassing the size range of molecules and nuclei which have been described as Rayleigh and Mie scatterers, respectively, after the individuals first responsible for theoretical treatment of the optical scattering properties. Contamination control for critical manufacturing environments is emphasized. Theoretical limits of detection using available lasers are defined and instrumental techniques resulting from compromises reached in their practical application are described. Discussion focuses on aerosol and is extended to include liquids and surfaces.
The Application of Condensation Nuclei Monitors to Clean Rooms
Authors: Ensor David , Donovan Robert
Published: November 2020

The instrument often used by aerosol researchers to detect 0.1-μm and smaller particles is the condensation nuclei monitor. The instrument will provide information about ultrafine particles in the clean room unobtainable by any other means. The principle of operation is to grow the particles by the condensation of water or alcohol onto a size that can be detected optically. The instrument was invented at the turn of the century by John Aitken.1 His instrument was an adiabatic expansion chamber followed by counting with a microscope after the droplets had settled onto a slide. In the last few years, automatic instruments have been commercially available. Since the condensation nuclei counter only detects the total number of particles, a particle size preseparator needs to be used with the instrument to obtain size distribution information. One type of preseparator is the "diffusion battery," and another is a differential mobility separator. The present application of the instrument is as a research tool to quantify the size spectrum of particles less than 1 μm. Measurements of clean-room condensation nuclei will be presented under a number of situations.
On Aerosol Size Distribution Measurement by Laser and White Light Optical Particle Counters
Authors: Liu Benjamin , Szymanski Wladyslaw , Ahn Kang-Ho
Published: November 2020

Light scattering optical particle counters are widely used for size distribution measurement of aerosol particles. The accuracy of the measured size distribution is dependent upon the response of the counter, which is affected by the refractive index and shape of the particles as well as by the optical design of the instrument, including the light source used. This paper addresses the measurement accuracy of the optical particle counter. Data are presented showing the response characteristics of several widely used commercial optical counters and the comparative size distribution measurement made by means of these instruments.
Vibration-Random Required
Authors: McGrath John , Kindig William
Published: November 2020

This paper presents the General Electric Aerospace Control Systems Department (ACSD) approach to hardware screening using random vibration as a stimulus. The proposed techniques were developed to achieve a screening program that is cost effective and is supportable in dollar payoff with increased productivity. Cost savings are realized by avoiding the assignment of a costly combined environment facility to each product line and reducing the number of test cycles required in the screening process.
Preliminary Studies of the Effects of Semiconductor Reagents on Polymers Containing Fluorine and of Trace Metallic Leachate from Molded Fluorocarbon Resin
Authors: Imbalzano John , Moody John
Published: November 2020

Traces of undesired materials in semiconductor devices are a serious processing deficiency and their elimination is widely sought. To this end, the effects of semiconductor reagents on discs molded from commercial materials of construction—perfluoroalkoxy (PFA) fluorocarbon resin and polyvinylidene fluoride (PVDF)—were assessed by measuring retained physical properties and by analytical microscopic inspection. At the National Bureau of Standards, Center for Analytical Chemistry, ultrapure nitric acid was stored, in a class 10 environment, in a container molded from PFA, and the level of leachable selected trace metallics was determined by graphite furnace atomic absorption spectrometry, flame emission spectrometry with repetitive optical scanning, and isotope dilution spark source mass spectrometry. The results from the exposure tests indicated that PVDF was significantly affected in the exposures; PFA was essentially unaffected. The amounts of leachable metallics from PFA were at or below low part-per-billion levels, since they were indistinguishable from those in the extractant blank.
Advanced Analysis Techniques for the Optimum Design of Clean Rooms
Authors: Deaves D. , Malam D.
Published: November 2020

This paper describes the application of advanced vibration analysis techniques and computational modeling to the design of microelectronics clean rooms. The ASAS (Atkins Stress Analysis System) and ASIST computer models were used to perform dynamic finite element analyses to determine the effects of transmitted structural forces on sensitive photolithographic equipment. The CAFE (Computer Aided Flow Evaluation) computer program was used to recirculate flow problems and evaluate the influences of representative obstructions on laminar air flow. Results of both analyses are presented.
Anion Analysis of High Purity Water
Authors: Cutler Frances
Published: November 2020

The semiconductor, power and pharmaceutical industries all require ultra high purity water for process control. While the type of demineralizer system used and the specific contaminants of concern may differ, the problems associated with maintaining and monitoring process water quality are similar.

The power industry has become increasingly concerned over the levels and transport of trace impurities in steam cycle systems as a result of corrosion problems experienced at supercritical generating units. On-line sodium analysis and continuous conductivity and acid conductivity measurements, used to monitor the high purity water in steam cycle systems, had not prevented the turbine and reheater corrosion in supercritical units.

In order to identify the contaminants responsible, ion chromatographic (IC) techniques were developed for analysis of chloride, fluoride, sulfate, formate, acetate, and glycolate at the ppb and ppt levels (parts per billion and parts per trillion). In addition to a discussion of the 1C procedures developed, the paper provides a summary of sample collection and conditioning methods and identifies potential interferences. The paper also examines the relationships between conductivity (or its reciprocal, resistivity), acid conductivity and the level of ionic contamination and presents evidence demonstrating that specific analytical techniques such as 1C need to be used in conjunction with conductivity or resistivity monitoring of ultra pure water.
Design and Control of a High Velocity, High Force Hydraulic Shock Test Machine
Authors: Favour John
Published: November 2020

This paper discusses the design and control of a large hydraulic shock testing device. The system is capable of peak velocities up to 10.2 m/s (400 in/sec) and peak forces up to 801 kN (180,000 lbs). The major challenges discussed are: 1) the concept design, 2) the specification and procurement of two very large (2500 gpm) electro-hydraulic servovalves and 3) the failsafe control of the servovalves and system response. The system performance is briefly discussed.
Bacteria as a Particle Source in Wafer Processing Equipment
Authors: Harned Wayne
Published: November 2020

Contamination control in integrated circuit wafer processing has become a major concern within the last two to three years. The surface particle counters and liquid particle counters have identified many particle sources within wafer processing equipment. One of these sources which is often overlooked is bacteria from the deionized water which is utilized in various etch, clean, rinser/dryers, scrubbers, and positive photoresist develop systems. Bacteria as live or dead microorganisms or as fragments of these microorganisms are a particle source and are a source of low level metals contamination.

Bacteria in equipment is overlooked by many integrated circuit manufacturers and was not addressed by equipment manufacturers until recently. In many cases, integrated circuit manufacturers monitor only final rinse tanks or quick dumps for bacteria level and do not sample the bacteria level from all sources of equipment. By testing for bacteria level at every source of water that comes in contact with the waters, one finds many areas of stagnant water where the bacteria counts are too-numerous-to-count (TNTC). The causes for these high bacteria counts are dead legs (plumbing within equipment which has stagnant water flow), water velocities too low, inadequately sized plumbing, and materials used in the plumbing of the equipment. The solutions to these problems must be addressed by equipment users and manufacturers modifying existing equipment and designing new equipment with bacteria control as a primary concern.
Low Level Radioactive Waste Disposal — Technology and Public Policy
Authors: Breiner Evelyn
Published: November 2020

The disposal of low level radioactive waste (LLRW) is becoming a political problem of the eighties. The problems with shallow land burial of LLRW in the recent past have indicated to the public that the operational technology is not adequate; therefore, studies are concentrating on the use of alternate technologies. These technologies consist of below and aboveground vaults, earth-mounded concrete bunkers, minded cavities, and augered holes. Each of these disposal concepts meet various performance criteria set for the disposal of LLRW. However, there are some performance criteria in each case, where the alternate disposal methods do not show any Improvement over shallow land burial. A trade-off is then necessary between sociopolitical acceptance and technical performance.
Optimization of Outgassing Bake-Out Temperatures and Duration of Space Systems
Authors: Scialdone John
Published: November 2020

Spacecraft systems are baked under vacuum to remove occluded and absorbed gases, solvents, plasticizers, and other materials acquired during their manufacture and exposure to the environment. The procedure is intended to reduce outgassing during subsequent vacuum exposure, decrease the quantity of potential contaminants which may deposit on critical surfaces, and limit the gaseous environment induced by the outgassing around a spacecraft. The determination of the temperature and of the duration of the bake which accomplishes a major portion of the outgassing and is not unduly high and long is of considerable importance for the integrity of the system and cost effectiveness.

In this paper, the percentage of the outgassing mass removed as a function of bake-out temperatures in the range of 45 to 85°C and bake durations of up to 200 hours have been provided in terms of the percentage removed after 24 hours of bake at 125°C. It has been shown, among others, that extending the bake-out from 60 hours to 100 hours or even to 200 hours will release only a few percent more of the outgassing at those bake temperatures. For example, in extending the bake from 60 hours to 200 hours at a temperature of 65° one removes only an additional 6 percent outgassing if the outgassing decays lineraly with time which is often found experimentally. On the other hand, the additional release is about 15 percent for the same conditions if the outgassing decays with the square root of time which represents a diffusive outgassing process. It is obvious that considerable savings in time and money can be made using as a guideline the data reported here to decide on the duration of the bake after having selected a maximum acceptable bake temperature which does not degrade the system. The data can also be used for the outgassing tests of materials in optimizing the test duration.
A Method of Structural Analysis For Small Items in A Random Vibration Environment, Part I.
Authors: Allen Hilary
Published: November 2020

To perform engineering analyses in the most cost-effective manner, engineers must eliminate noncritical design items from a detailed analysis program and concentrate on the marginal and critical design items. This paper shows an approach to accomplishing this objective through the use of a rapid single-degree-of-freedom analysis. Part I develops equations for determining dynamic stresses on structural items modeled as simple beams and presents a nondimensional method for determining the equivalent spring rate of a variable-stiffness beam. Part II presents a step-by-step example that provides the deflection, equivalent stiffness, frequency, and dynamic stress on two different beam configurations with their predicted times-to-failure. In addition, the deflection and frequency results from a finite-element-model analysis of two tapered brackets are compared with the results from the nondimensional variable stiffness beam method developed previously.
Study of Constant Airflow Rate and Constant Room Pressure Control Systems for Physical Containment Laboratories
Authors: Takahashi Atsushi , Okada Takao
Published: November 2020

This study discusses various control systems that can keep the room pressure and supply/exhaust airflow rate at constant levels in "other rooms" of a highly airtight containment facility when the supply/exhaust airflow is shut off in one of the rooms for decontamination purposes. This study has shown that the constant air volume control system (CAV) allows hysteresis to occur at small differentials on the performance curve of the static pressure differentials and that this hysteresis can cause wide fluctuations in room pressure. In contrast, the variable air volume, central processing unit (VAV-CPU) control system can maintain both airflow rates and room pressures. Each room pressure was controllable to the set level, with an error of less than ±0.5 mmH2O even during transient distur bances. This control system limited fluctuations in the airflow to and from each room to 5 percent during the transient responses. This control system also allows power savings in the operation of supply/exhaust fans, because of the reduced airflow rate and the static pressure of the fans, and is considered to be an excellent control system.
Human Occupational and Industrial Vibration
Authors: Wasserman Donald
Published: November 2020

The medical/epidemiological and engineering aspects of both whole-body and hand-arm occupational/industrial vibration are discussed. Eight million workers in the U.S. are exposed to occupational vibration. Current hand-arm and whole-body vibration standards are also presented, along with engineering control and work practice recommendations for minimizing worker exposure to vibration.
The Effects of Contamination on Semiconductor Manufacturing Yield
Authors: Osburn Carlton , Berger Henry , Donovan Robert , Jones Gary
Published: November 2020

The challenges associated with controlling particulate and chemical contamination to achieve high semiconductor device yields are demonstrated with data showing the influence of cleanroom air, semiconductor processes and tools, gases, chemicals, and Dl water. Because typical film thicknesses are much smaller than pattern feature sizes, defects that are as small as one hundredth of the lithographic dimension must be controlled. Scaling device dimensions by a factor of 1/3 to 1/2 will require almost a factor of 10 reduction of particulate levels in order to maintain the prescaling yield. To achieve a 78 percent yield (0.25 defects/cm2) in a typical submicron process containing 250 process steps, each step must contribute no more than 0.001 killer defects/cm2 on average. Storage of wafers for 1 hr in a Class 1 vertical laminar flow cleanroom is sufficient to reach this level. Considerably more defects are introduced in other process steps involving automated tools or chemical/gas exposure. As device dimensions are reduced, the contamination associated with liquids will become relatively more important than that from gases and cleanroom air.
Wastewater Effluent vs. Safety In Its Reuse: State-of-the-Art
Authors: Shahalam Abul
Published: November 2020

A state-of-the-art review of the human health risks associated with the reuse of wastewater effluent is presented. The subject is of much concern as the need for wastewater becomes more critical in the wake of worldwide shortages of good quality water.

The subject of wastewater reuse has been a controversial subject during the last few decades due to the fear of harmful effects on human health and the environment. But recent technology relating to wastewater treatment methods has changed the outlook significantly.

The article offers a broad review of the available data on wastewater treatment performance particularly relating to the removal of pathogenic agents. The areas specifically covered are: wastewater quality from various wastewater systems with respect to pathogens; available conventional and nonconventional wastewater treatment technologies; available laboratory methodologies for enumerating the pathogenic state of wastewater and their reliabilities; various methodologies of preuse disinfection of wastewater and their feasibility for practical use; and the pathogen survival rates in liquid water and various other media. The human health risks associated with wastewater reuse in agriculture are assessed at the present level of understanding and are discussed in detail. Areas that need further investigations are delineated.
Comparing Particle Counters: Cost vs. Reproducibility
Authors: Cooper Douglas , Grotzinger Stephen
Published: November 2020

Particle counters are used in evaluating particle concentrations in liquids and gases and on surfaces. Even for the same purpose, several types are commercially available. Many factors will go into a decision about which to buy. These include upper and lower particle size detection limits; particle size subdivisions; data display, communication, and analysis capabilities; ease of use; reliability; accuracy; reproducibility (precision); and cost. A method is presented to allow comparisons based on reproducibility of measurements and cost.
Status and Needs of In-Situ Real-time Process Particle Detection
Authors: Bowling R. , Larrabee Graydon , Fisher Wayne
Published: November 2020

Particle defects play a major role in yield losses in semiconductor device fabrication. It is generally acknowledged that about 50 percent of all yield losses are due to particles. Processing of devices with 0.35 to 0.5 μm minimum feature sizes will exacerbate the effects of particles due to the large relative abundance of submicron particles. The cleanroom is no longer the major particle contributor because current state-of-the-art cleanrooms have less than 10 particles (<0.5 μm) per cubic foot. Particles in processing equipment now play the dominant role in wafer contamination. An analysis of the status and needs of particle detection techniques for semiconductor processing equipment and processes clearly shows that they are inadequate to meet the requirements of the next generation of devices. Detection limits must be improved both in terms of particle diameter and in the number of particles on a wafer. An experimental laser particle counter was fabricated and used to show that such a detector would be extremely useful for in-vacuum realtime particle detection. Experimental studies on wafer surface measurements show that current wafer surface scanning techniques cannot provide the level of detection needed for future devices. Ideas for a new generation of particle detection equipment are presented.
An Automated System for Contamination-Controlled Processing of Precision Instruments
Authors: Stepien Thomas
Published: November 2020

The design and assembly of an automated system for cleaning and assembly of precise electromechanical instruments in a cleanroom environment is described. Precision contamination-controlled automation implies controlling processes that substantially exceed the ability of humans and controlling contamination at a Class 1 cleanroom level. The automated system described has demonstrated the capability to meet these requirements by successfully processing inertial instruments formerly processed by manual operators. It performs all operations while maintaining the internal processing environment at a Class 1 level.
Particle Adhesion to Solid Surfaces
Authors: Hecht Lewis
Published: November 2020

This review paper provides cleanroom technologists with an up-to-date overview on the subject of particle adhesion to solid surfaces. The discussion consists of four sections: (1) fundamental concepts of adhesion, (2) the nature of a solid surface, (3) the physical properties of particles, and (4) comments on the various theories of particle adhesion to solid surfaces. Some practical examples are also cited. A numeric example of adhesive forces as a function of particle size is presented in detail. The appendix contains references to other useful sources of information in the technical literature.
A Captive Store Flight Vibration Simulation Project
Authors: Szymkowiak E. , Silver W.
Published: November 2020

Military electronic equipment has become increasingly more sophisticated and, with greater complexity, very often less reliable. The project described here constitutes a complete effort, using as a test bed an AN/ALQ-131 electronic countermeasures external store, captive to an F-Ill F aircraft. The project included flight vibroacoustic data acquisition and reduction, development of a simulation approach designed to secure a high degree of matching field and laboratory environments, flight life simulation in the laboratory using a time compression factor of 20.5 to 1, and comparison of field and laboratory reliability. The simulation, completed rapidly and at low cost, resulted in very high correlation of field and laboratory failure types and a reasonable correlation of reliability. The relationships between vibration response and flight conditions measured during this project were considerably different than those predicted by the generic model for assembled external stores in MIL-STD-810D.
A Sequential Sampling Plan for Federal Standard 209
Authors: Cooper Douglas , Milholland Dan
Published: November 2020

A sequential sampling plan is developed to match the operating characteristic (OC) curve of the Federal Standard 209D single sampling plan as a possible revision to the Standard. The sequential sampling plan gives virtually identical probabilities of passing or failing that a single sample gives. However, the sequential plan would save 80 percent of the sampling time for very clean air, about 35 percent of the sampling time for air that is just at the Class Limit, and more than 80 percent of the sampling time for air that is more than 2.5 times as contaminated as the Class Limit.
Point-of-Use Monitoring for Ultrapure Water Applications in the Semiconductor Industry
Authors: Frith Clifford
Published: November 2020

Major improvements in water purification processes for the semiconductor industry have been reported over the past several years. Improved quality control testing programs have been instituted in major semiconductor facilities throughout the world. More recently, the quality of water produced at the central purification facility, as well as distribution for point-of-use (POU), has been verified with continuous on-line instrumentation versus the time-dependent lab analysis.

This presentation will document the most recent data for ultrapure water measurement at the POU, including the actual rinsing process. The data indicate that further research and development is required for improving the quality of the water in the actual rinsing process. In previous reports, the quality of water has not been monitored in the actual rinsing process and therefore information recorded is not complete. The pure water at the use point must he continuously monitored and verified for best results in the wafer rinsing process.
Infrared Sensor Calibration Facility
Authors: Hazen John , Scorsone L.
Published: November 2020

The Boeing Infrared Sensor (BIRS) Calibration Facility represents a major capital investment by The Boeing Company in optical and infrared technology. The facility was designed and built for calibrating and testing new generation large aperture long wave infrared (LWIR) sensors, seekers, and related technologies. The capability exists to perform both radiometric and goniometric calibrations of large infrared sensors under simulated environmental operating conditions. The system is presently configured for endoatmospheric calibrations with a uniform background field that can be set to simulate the expected mission background levels. During calibration, the sensor under test is also exposed to expected mission temperatures and pressures within the test chamber. The facility could be converted for exoatmospheric testing.

The first major test runs in the facility were completed during 1989 with very satisfactory results. This paper will describe system configuration and hardware elements, and will address the modifications made to date.

Pitt-Des Moines. Inc. (PDM) of Pittsburgh, Pennsylvania, was the contractor for the turnkey design and construction of the test chambers and thermal vacuum systems. Hughes Danbury Optical Systems (formerly Perkin Elmer Optical Systems) was the hardware supplier for the optical hardware. The Boeing Company performed all optical assembly, integration, testing, and alignment on-site.