Academic literature on the topic 'Integrated Computer Modeling'

With the growth of information technologies in the field of computer-aided design, the concept of CAD acquires new meaning and changes the contents. More and more a new definitions, i.e. Building Information Modeling - BIM, Fabrication Information Modeling - FIM, Integrated Structural Modeling - ISM, Building Lifecycle Management - PLM and others are encountered, the concept of which may be described as way to develop the strategy of building project design, construction, and maintenance management based on the computer aided modeling and simulation technologies. Examine BIM application in building design process it can be assumed that of object modeling and simulation technique comprises a full range of actions starting from the development of virtual model of the project under consideration, describing all physical parameters characteristic of a real structure, defining the conditions of its position. Then analysis of model behavior under real maintenance conditions is performed: effects of different character are described and the results obtained are analyzed. The results received by next step are presented in common technical documentation form: general arrangement and erection drawings are generated, final detailing of connections and structural elements in the form of shop drawing or NC code is performed, bill of materials, cut lists, various reports, specifications and estimates are composed. During the last five years there is strong request from the market for the state-of-the-art computer-aided design applications developed to meet the needs and requirements of the Architectural, Engineering, and Construction as well as Plant, Process, and Power industries, for high performance, flexible and versatile tools with extended graphics integration to simulation and analysis systems within a user-friendly design environment that allows the close emulation of natural design phases and workflow to which structural are accustomed. This could became possible due to the innovative development of ‘new generation’ structural software application capable to maintain an intelligent and true 3D real-world simulated structure containing all the information required for the general and detailed design, fabrication and construction of engineering structures, enabling designers to operate intuitively in the adaptive high-performance real-time visual modeling environment while simultaneously achieving high-quality results by applying powerful simulation, analysis and optimization methods which would guarantee a rational and effective choice of the constructive decision. It has to be flexible to enable external best of breed vertical market products to be linked to the application and hence creating an open design environment; this enables members of a workgroup to collaborate effectively, performing the multiple tasks associated with construction design.

ABSTRACT This paper examines the potential use of computer models to estimate environmental impacts from oil spills. Computer simulation models for oil spills have long been used for risk analysis and have continually improved over the past few decades. Beyond risk analysis, however, these modeling tools could contribute to the estimation of the environmental impacts such as species mortality and shoreline contact. Proposed activities such as offshore oil and gas exploration and development can be analyzed using models that integrate spill-simulation capability with environmental resource and toxicological data. To estimate the potential use and reasonableness of such models for oil-spill impact analysis, the authors have applied a commercially available state-of-the-art spill model using previously unavailable historical winds and currents data and spill events extracted from the oil-spill record for the Outer Continental Shelf (OCS) in the Gulf of Mexico (GOM). This is one of the first efforts to bring together such complete data sets for modeling effects on so broad a geographic and temporal scale. Such information is valuable in determining the reasonableness and appropriateness of model use for impact analysis of future exploration, development, and production activities.

Competition generated the requirement of quick decisions at engineering activities. As a consequence, application of advanced computer modeling in engineering design needs application of intelligent computer methods to assist human decision making. A powerful CAD/CAM system with a comprehensive range of sophisticated modeling tools for describing engineering objects and programming tools for creating modeling procedures constitutes an appropriate environment to accept intelligent methods. The only way of survival for companies producing mechanical products on the competitive edge seems application of advanced modeling together with intelligent decision making. Much modeling, problem solving, database handling, visualization and other methods are involved in a typical computer-based engineering process. This process recently relies upon an integrated set of modeling tools and an integrated product database. Involving intelligent computer methods is a great challenge in this field. This paper surveys advanced modeling from the point of view of application of intelligent methods. It is organized as follows. A characterization of state of the art in advanced engineering modeling reveals important issues to be discussed in this paper. Following this, worldwide network-based group work of engineers is discussed. Human computer interaction (HCI) and network communication methods as important aspects of computer-aided engineering are outlined. Then recent development results in modeling of mechanical systems with special emphasis on integrated modeling of mechanical products, especially well-engineered shapes, are introduced. Finally, virtual manufacturing as an area of involving intelligent methods in CAD/CAM technology is discussed.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.
Includes bibliographical references (leaf 38).
by SunMan Patrick Wu.
M.Eng.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 215-225).
Planarization processes are a key enabling technology for continued performance and density improvements in integrated circuits (ICs). Dielectric material planarization is widely used in front-end-of-line (FEOL) processing for device isolation and in back-end-of-line (BEOL) processing for interconnection. This thesis studies the physical mechanisms and variations in the planarization using chemical mechanical polishing (CMP). The major achievement and contribution of this work is a systematic methodology to physically model and characterize the non-uniformities in the CMP process. To characterize polishing mechanisms at different length scales, physical CMP models are developed in three levels: wafer-level, die-level and particle-level. The wafer-level model investigates the CMP tool effects on wafer-level pressure non-uniformity. The die-level model is developed to study chip-scale non-uniformity induced by layout pattern density dependence and CMP pad properties. The particle-level model focuses on the contact mechanism between pad asperities and the wafer. Two model integration approaches are proposed to connect wafer-level and particle-level models to the die-level model, so that CMP system impacts on die-level uniformity and feature size dependence are considered. The models are applied to characterize and simulate CMP processes by fitting polishing experiment data and extracting physical model parameters. A series of physical measurement approaches are developed to characterize CMP pad properties and verify physical model assumptions. Pad asperity modulus and characteristic asperity height are measured by nanoindentation and microprofilometry, respectively. Pad aging effect is investigated by comparing physical measurement results at different pad usage stages. Results show that in-situ conditioning keeps pad surface properties consistent to perform polishing up to 16 hours, even in the face of substantial pad wear during extended polishing. The CMP mechanisms identified from modeling and physical characterization are applied to explore an alternative polishing process, referred to as pad-in-a-bottle (PIB). A critical challenge related to applied pressure using pad-in-a-bottle polishing is predicted.
by Wei Fan.
Ph.D.

As operating frequency increases and device sizes shrink, the complexity of current state-of-the-art designs has increased dramatically. One of the main contributors to this complexity is high speed interconnects. At high frequencies, interconnects become dominant contributors to signal degradation, and their effects such as delays, reflections, and crosstalk must be accurately simulated. Time domain analysis of such structures is however very difficult because, at high frequencies, they must be modeled as distributed transmission lines which, after discretization, result in very large networks. In order to improve the simulation efficiency of such structures, model order reduction has been proposed in the literature. Conventional model order reduction methods based on Krylov subspace have a number of limitations in many practical simulation problems. This restricts their usefulness in general commercial simulators.
In this thesis, a number of new reduction techniques were developed in order to address the key shortcomings of current model order reduction methods. Specifically a new approach for handling macromodels with a very large number of ports was developed, a multi-level reduction and sprasification method was proposed for regular as well as parametric macromodels, and finally a new time domain reduction method was presented for the macromodeling of nonlinear parametric systems. Using these approaches, CPU speedups of 1 to 2 orders of magnitude were obtained.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.
Leaf 108 blank.
Includes bibliographical references (leaves 106-107).
A quantitative model capturing pattern dependent effects in plasma etching of integrated circuits (ICs) is presented. Plasma etching is a key process for pattern formation in IC manufacturing. Unfortunately, pattern dependent non-uniformities arise in plasma etching due to microloading and RIE lag. This thesis contributes a semi-empirical methodology for capturing and modeling microloading, RIE lag, and related pattern dependent effects. We apply this methodology to the study of interconnect trench etching, and show that an integrated model is able to predict both pattern density and feature size dependent non-uniformities in trench depth. Previous studies of variation in plasma etching have characterized microloading (due to pattern density), and RIE lag (aspect ratio dependent etching or ARDE) as distinct causes of etch non-uniformity for individual features. In contrast to these previous works, we present here a characterization and computational methodology for predicting IC etch variation on a chip scale that integrates both layout pattern density and feature scale or ARDE dependencies. The proposed integrated model performs well in predicting etch variation as compared to a pattern density only or feature scale only model.
by Kwaku O. Abrokwah.
M.Eng.

Information systems development research has documented the importance and the difficulty of eliciting requirements from users. Research on the use of Group Support Systems (GSS) for requirements elicitation led to development of the Collaborative Software Engineering Methodology (CSEM) and identified the need for collaborative methods and tools to provide a dynamic picture of the business processes that a system must support. Recent research suggests that scenarios can fill this need. A review of the scenario literature showed that although there is widespread agreement on the usefulness of scenarios, there are many questions on how to implement a user-focused, scenario-based systems development process. The purpose of this research was to advance understanding in this area and to determine: What are the collaborative modeling processes, tools, and facilitation techniques needed to effectively elicit scenarios from users in a group environment? A two-phase, multi-method systems development research approach was used. The first phase focused on use of a general-purpose GSS for collaborative scenario elicitation. A conceptual framework and initial methodology were developed and then evaluated during exploratory case studies and a laboratory experiment. The second phase focused on development and evaluation of a special-purpose GSS and methodology. Phase I results showed that: users can easily define scenarios which provide rich pictures of the problem domain; an iterative, collaborative methodology with scenario and action prompts is needed to ensure scenario completeness; and limitations of general-purpose GSS negatively impacted productivity. The Collaborative Distributed Scenario and Process Analyzer (SPA) provides integrated textual scenario and graphical process modeling capabilities which successfully overcame these limitations. This research made several contributions. CSEM was extended to define scenario usage opportunities throughout development. Scenario content, form, group process and facilitation techniques were defined for collaborative scenario elicitation using a general-purpose GSS, which can be used now by practitioners. A special-purpose GSS tool (SPA) was developed and integrated into a comprehensive methodology which allows user groups to rapidly define and analyze scenarios in face-to-face and distributed settings. Finally, flexibility designed into SPA opens up opportunities for many other uses for SPA and serves as a first-step towards a build-your-own GSS tool.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.
Includes bibliographical references (p. 173-176).
Copper metallization has emerged as the leading interconnect technology for deep sub-micron features, where electroplating and chemical mechanical polish (CMP) processes have a vital role in the fabrication of integrated circuits. The processes both suffer from a similar problem: the copper electroplated profiles and the polished surface exhibit pattern dependent topography. In this thesis, a methodology for the characterization and modeling of pattern dependent problems in copper interconnect topography is developed. For the electroplating process, the methodology consists of test structure and mask design to examine feature scale copper step height and the height of copper array regions as a function of underlying layout parameters. Semi-empirical response surface models are then generated with model parameters extracted from conventional and superfill plating processes. Once the models are calibrated, layout parameters including pattern density, line width distributions, and line length are extracted for each cell in a 40 gm by 40 tm discretization of any random chip layout. Then, a chip-scale prediction is achieved by simulating generalized average heights for each grid cell across the entire chip. The prediction result shows root mean square errors of less than 1000 A for array height and around 500 A for step height. This methodology provides the first known chip-scale prediction of electroplated topography. For pattern dependencies in copper CMP, this thesis focuses on the development of test structures and masks (including multi-level structures) to identify key pattern effects in both single-level and multi-level polishing.
(cont.) Especially for the multi-level studies, electrical test structures and measurements in addition to surface profile scans are seen to be important in accurately determining thickness variations. The developed test vehicle and characterization of copper dishing and oxide erosion serve as a basis for further pattern dependent model development. Finally, integration of electroplating and CMP chip-scale models is illustrated; the simulated step and array heights as well as topography pattern density are used as an input for the initial starting topography for CMP simulation of subsequent polishing profile evolution.
by Tae Hong Park.
Ph.D.

Abstract Increasing performance requirements of present and future mechanical systems, along with the development of cost effective high performance computers, is creating an environment where new designs require the support of numerical simulations to be successful both technically and commercially. This new design environment requires an integrated systems approach to design with more exhaustive and accurate engineering analyses being made earlier, faster, and at reduced cost and physical risk. The use of analysis in design provides better prototypes, and the same computer models provide a basis for properly interpreting/understanding empirical results. The combined effect is a shorter development cycle and a superior product based on well understood principles. FMC, because of its diversified product lines has recognized this need and has been developing verified numerical simulation tools in support of design activities. The overall objective has been to develop verified modeling and numerical simulation capabilities to predict the performance of a total mechanical system. Our approach is to incrementally develop, validate, and integrate subsystem models into a total system level model that includes all significant subsystem interactions. Hardware and software tools for computer graphic rendering, test data acquisition, reduction, and comparison are also being developed that facilitate our goals. This presentation will provide a summary of our computer simulation and validation activities in areas of finite element techniques, kinematic and dynamic analyses, vehicle systems analysis, computer-aided testing, interactive simulation, dynamic modeling using symbolic code generation, high-performance computing, and scientific visualization.

One of the well-known results of the theory of management is the fact, that multi-stage hierarchical organization of management is unstable. Hence, the ideas expressed in a number of works by Don Tapscott on advantages of network organization of businesses over vertically integrated ones is clear. While studying the basic tendencies of business organization in the conditions of globalization, computerization and internetization of the society and the results of the financial activities of the well-known companies, the authors arrive at the conclusion, that such companies, as IBM, Boeing, Mercedes-Benz and some others companies have not been engaged in their traditional business for a long time. Their partner networks performs this function instead of them. The companies themselves perform the function of system integrators. The Tapscott’s idea finds its confirmation within the framework of a new powerful direction of the development of the modern interdisciplinary science – the theory of the complex networks (CN) [2]. CN-s are multifractal objects, the loss of multifractality being the indicator of the system transition from more complex state into more simple state. We tested the multifractal properties of the data using the wavelet transform modulus maxima approach in order to analyze scaling properties of our company. Comparative analysis of the singularity spectrumf(®), namely, the difference between maximum and minimum values of ® (∆ = ®max ¡ ®min) shows that IBM company is considerably more fractal in comparison with Apple Computer. Really, for it the value of ∆ is equal to 0.3, while for the vertically integrated company Apple it only makes 0.06 – 5 times less. The comparison of other companies shows that this dependence is of general character. Taking into consideration the fact that network organization of business has become dominant in the last 5-10 years, we carried out research for the selected companies in the earliest possible period of time which was determined by the availability of data in the Internet, or by historically later beginning of stock trade of computer companies. A singularity spectrum of the first group of companies turned out to be considerably narrower, or shifted toward the smaller values of ® in the pre-network period. The latter means that dynamic series were antipersistant. That is, these companies‘ management was rigidly controlled while the impact of market mechanisms was minimized. In the second group of companies if even the situation did changed it did not change for the better. In addition, we discuss applications to the construction of portfolios of stock that have a stable ratio of risk to return.

Background Lung cancer is the number one cause of cancer death worldwide.(1) It is the fifth most commonly diagnosed cancer in Australia (12,741 cases diagnosed in 2018) and the leading cause of cancer death.(2) The number of years of potential life lost to lung cancer in Australia is estimated to be 58,450, similar to that of colorectal and breast cancer combined.(3) While tobacco control strategies are most effective for disease prevention in the general population, early detection via low dose computed tomography (LDCT) screening in high-risk populations is a viable option for detecting asymptomatic disease in current (13%) and former (24%) Australian smokers.(4) The purpose of this Evidence Check review is to identify and analyse existing and emerging evidence for LDCT lung cancer screening in high-risk individuals to guide future program and policy planning. Evidence Check questions This review aimed to address the following questions: 1. What is the evidence for the effectiveness of lung cancer screening for higher-risk individuals? 2. What is the evidence of potential harms from lung cancer screening for higher-risk individuals? 3. What are the main components of recent major lung cancer screening programs or trials? 4. What is the cost-effectiveness of lung cancer screening programs (include studies of cost–utility)? Summary of methods The authors searched the peer-reviewed literature across three databases (MEDLINE, PsycINFO and Embase) for existing systematic reviews and original studies published between 1 January 2009 and 8 August 2019. Fifteen systematic reviews (of which 8 were contemporary) and 64 original publications met the inclusion criteria set across the four questions. Key findings Question 1: What is the evidence for the effectiveness of lung cancer screening for higher-risk individuals? There is sufficient evidence from systematic reviews and meta-analyses of combined (pooled) data from screening trials (of high-risk individuals) to indicate that LDCT examination is clinically effective in reducing lung cancer mortality. In 2011, the landmark National Lung Cancer Screening Trial (NLST, a large-scale randomised controlled trial [RCT] conducted in the US) reported a 20% (95% CI 6.8% – 26.7%; P=0.004) relative reduction in mortality among long-term heavy smokers over three rounds of annual screening. High-risk eligibility criteria was defined as people aged 55–74 years with a smoking history of ≥30 pack-years (years in which a smoker has consumed 20-plus cigarettes each day) and, for former smokers, ≥30 pack-years and have quit within the past 15 years.(5) All-cause mortality was reduced by 6.7% (95% CI, 1.2% – 13.6%; P=0.02). Initial data from the second landmark RCT, the NEderlands-Leuvens Longkanker Screenings ONderzoek (known as the NELSON trial), have found an even greater reduction of 26% (95% CI, 9% – 41%) in lung cancer mortality, with full trial results yet to be published.(6, 7) Pooled analyses, including several smaller-scale European LDCT screening trials insufficiently powered in their own right, collectively demonstrate a statistically significant reduction in lung cancer mortality (RR 0.82, 95% CI 0.73–0.91).(8) Despite the reduction in all-cause mortality found in the NLST, pooled analyses of seven trials found no statistically significant difference in all-cause mortality (RR 0.95, 95% CI 0.90–1.00).(8) However, cancer-specific mortality is currently the most relevant outcome in cancer screening trials. These seven trials demonstrated a significantly greater proportion of early stage cancers in LDCT groups compared with controls (RR 2.08, 95% CI 1.43–3.03). Thus, when considering results across mortality outcomes and early stage cancers diagnosed, LDCT screening is considered to be clinically effective. Question 2: What is the evidence of potential harms from lung cancer screening for higher-risk individuals? The harms of LDCT lung cancer screening include false positive tests and the consequences of unnecessary invasive follow-up procedures for conditions that are eventually diagnosed as benign. While LDCT screening leads to an increased frequency of invasive procedures, it does not result in greater mortality soon after an invasive procedure (in trial settings when compared with the control arm).(8) Overdiagnosis, exposure to radiation, psychological distress and an impact on quality of life are other known harms. Systematic review evidence indicates the benefits of LDCT screening are likely to outweigh the harms. The potential harms are likely to be reduced as refinements are made to LDCT screening protocols through: i) the application of risk predication models (e.g. the PLCOm2012), which enable a more accurate selection of the high-risk population through the use of specific criteria (beyond age and smoking history); ii) the use of nodule management algorithms (e.g. Lung-RADS, PanCan), which assist in the diagnostic evaluation of screen-detected nodules and cancers (e.g. more precise volumetric assessment of nodules); and, iii) more judicious selection of patients for invasive procedures. Recent evidence suggests a positive LDCT result may transiently increase psychological distress but does not have long-term adverse effects on psychological distress or health-related quality of life (HRQoL). With regards to smoking cessation, there is no evidence to suggest screening participation invokes a false sense of assurance in smokers, nor a reduction in motivation to quit. The NELSON and Danish trials found no difference in smoking cessation rates between LDCT screening and control groups. Higher net cessation rates, compared with general population, suggest those who participate in screening trials may already be motivated to quit. Question 3: What are the main components of recent major lung cancer screening programs or trials? There are no systematic reviews that capture the main components of recent major lung cancer screening trials and programs. We extracted evidence from original studies and clinical guidance documents and organised this into key groups to form a concise set of components for potential implementation of a national lung cancer screening program in Australia: 1. Identifying the high-risk population: recruitment, eligibility, selection and referral 2. Educating the public, people at high risk and healthcare providers; this includes creating awareness of lung cancer, the benefits and harms of LDCT screening, and shared decision-making 3. Components necessary for health services to deliver a screening program: a. Planning phase: e.g. human resources to coordinate the program, electronic data systems that integrate medical records information and link to an established national registry b. Implementation phase: e.g. human and technological resources required to conduct LDCT examinations, interpretation of reports and communication of results to participants c. Monitoring and evaluation phase: e.g. monitoring outcomes across patients, radiological reporting, compliance with established standards and a quality assurance program 4. Data reporting and research, e.g. audit and feedback to multidisciplinary teams, reporting outcomes to enhance international research into LDCT screening 5. Incorporation of smoking cessation interventions, e.g. specific programs designed for LDCT screening or referral to existing community or hospital-based services that deliver cessation interventions. Most original studies are single-institution evaluations that contain descriptive data about the processes required to establish and implement a high-risk population-based screening program. Across all studies there is a consistent message as to the challenges and complexities of establishing LDCT screening programs to attract people at high risk who will receive the greatest benefits from participation. With regards to smoking cessation, evidence from one systematic review indicates the optimal strategy for incorporating smoking cessation interventions into a LDCT screening program is unclear. There is widespread agreement that LDCT screening attendance presents a ‘teachable moment’ for cessation advice, especially among those people who receive a positive scan result. Smoking cessation is an area of significant research investment; for instance, eight US-based clinical trials are now underway that aim to address how best to design and deliver cessation programs within large-scale LDCT screening programs.(9) Question 4: What is the cost-effectiveness of lung cancer screening programs (include studies of cost–utility)? Assessing the value or cost-effectiveness of LDCT screening involves a complex interplay of factors including data on effectiveness and costs, and institutional context. A key input is data about the effectiveness of potential and current screening programs with respect to case detection, and the likely outcomes of treating those cases sooner (in the presence of LDCT screening) as opposed to later (in the absence of LDCT screening). Evidence about the cost-effectiveness of LDCT screening programs has been summarised in two systematic reviews. We identified a further 13 studies—five modelling studies, one discrete choice experiment and seven articles—that used a variety of methods to assess cost-effectiveness. Three modelling studies indicated LDCT screening was cost-effective in the settings of the US and Europe. Two studies—one from Australia and one from New Zealand—reported LDCT screening would not be cost-effective using NLST-like protocols. We anticipate that, following the full publication of the NELSON trial, cost-effectiveness studies will likely be updated with new data that reduce uncertainty about factors that influence modelling outcomes, including the findings of indeterminate nodules. Gaps in the evidence There is a large and accessible body of evidence as to the effectiveness (Q1) and harms (Q2) of LDCT screening for lung cancer. Nevertheless, there are significant gaps in the evidence about the program components that are required to implement an effective LDCT screening program (Q3). Questions about LDCT screening acceptability and feasibility were not explicitly included in the scope. However, as the evidence is based primarily on US programs and UK pilot studies, the relevance to the local setting requires careful consideration. The Queensland Lung Cancer Screening Study provides feasibility data about clinical aspects of LDCT screening but little about program design. The International Lung Screening Trial is still in the recruitment phase and findings are not yet available for inclusion in this Evidence Check. The Australian Population Based Screening Framework was developed to “inform decision-makers on the key issues to be considered when assessing potential screening programs in Australia”.(10) As the Framework is specific to population-based, rather than high-risk, screening programs, there is a lack of clarity about transferability of criteria. However, the Framework criteria do stipulate that a screening program must be acceptable to “important subgroups such as target participants who are from culturally and linguistically diverse backgrounds, Aboriginal and Torres Strait Islander people, people from disadvantaged groups and people with a disability”.(10) An extensive search of the literature highlighted that there is very little information about the acceptability of LDCT screening to these population groups in Australia. Yet they are part of the high-risk population.(10) There are also considerable gaps in the evidence about the cost-effectiveness of LDCT screening in different settings, including Australia. The evidence base in this area is rapidly evolving and is likely to include new data from the NELSON trial and incorporate data about the costs of targeted- and immuno-therapies as these treatments become more widely available in Australia.