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IMPROVING ENERGY EFFICIENCY IN SEMICONDUCTOR HVAC SYSTEMS
No full textThe semiconductor industry plays a major role in modern technology, including consumer electronics and advancing computing systems. As demand for semiconductors continues to grow, the need for efficient and sustainable processes has increased. A critical focus within the industry is optimizing cleanroom environments, which are essential for contamination-free production. Cleanrooms must meet strict standards for air quality, temperature, and humidity, but maintaining these conditions requires significant financial investment, energy consumption, and water usage. Addressing these challenges is essential to improving operational efficiency and reducing environmental impact.
Optimizing HVAC systems in semiconductor cleanrooms provides an opportunity to address these issues. This project focuses on developing and analyzing various HVAC airflow configurations tailored for different cleanroom classifications. The primary objective is to identify the optimal configuration that balances energy usage, cost-effectiveness, water consumption, and environmental responsibility. Through modeling and analysis, various cleanroom HVAC systems were created and evaluated for their ability to supply clean air efficiently while maintaining compliance with air quality, temperature, and humidity standards. Emphasis was placed on reducing energy usage and emissions without compromising cleanroom integrity. This initiative is driven by the growing demand for sustainable manufacturing practices and the continuous expansion of the semiconductor sector. With rising global energy costs and tightening environmental regulations, HVAC optimization can reduce operational expenses and support sustainability goals. Innovative airflow configurations and energy-efficient designs can also help establish new industry standards for cleanroom operation. This report analyzes four airflow configurations, labeled Exhibits A through D, using ISO 4, ISO 5, and ISO 7 cleanrooms to simulate different manufacturing processes. Exhibit A models fully independent cleanrooms with no air reuse. Exhibit B connects the cleanrooms in sequence, recycling air between different classifications. Exhibit C mirrors A but incorporates return air into the feed stream. Exhibit D combines both return and recycled air strategies across interconnected cleanrooms. In Stage 1, all configurations were modeled under extreme hot and cold dry conditions over a six-month period. In Stage 2, daily temperature and humidity data from Chandler, Arizona were used for a more realistic, year-round cost comparison. The economic analysis evaluated financial feasibility using cash flow diagrams that included capital costs, utility expenses (electricity, municipal water, R-32, and ultra-pure water), maintenance, and equipment depreciation. Utility rates were sourced from the City of Phoenix (2024), and water costs from Whitehead (2020). A 12-year Net Present Value (NPV) analysis using a 20 percent minimum acceptable return rate was conducted. In Stage 1, Exhibit D was the most cost-efficient option (NPV: 389,298,169). In Stage 2, Exhibit D again performed best (NPV: 133,110,000). The use of real daily data in Stage 2 resulted in lower projected losses overall. In Stage 1, heating and cooling dominated electricity usage due to the modeled extremes. Assumptions in equipment sizing and weather profiles introduced uncertainty. Stage 2 results, based on daily climate data, showed greater accuracy, with humidifier operation emerging as a key cost driver. However, using daily averages may obscure fluctuations in heating and cooling demands, especially when temperatures hover near the cleanroom setpoint. This limitation can affect the accuracy of utility cost estimates. Despite these uncertainties, the relative rankings of configurations in the decision matrix are unlikely to change. Refining equipment sizing and incorporating more detailed weather data could improve future modeling. Additional considerations, such as varying air change rates and fan filter efficiencies, may provide further optimization opportunities. Based on this study, Exhibit D is expected to remain the most effective configuration. This work highlights key cost drivers and areas for future refinement in cleanroom HVAC system design
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Aerosol and precipitation composition at a coastal New England site (Acadia National Park): implications for air quality and aerosol composition during cold air outbreaks
No full text<jats:p>Co-located measurements of aerosol and wet deposition composition at Acadia National Park reveal insights into aerosol–precipitation interactions.</jats:p>
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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