Matching Items (43,913)
Description
The wood-framing trade has not sufficiently been investigated to understand the work task sequencing and coordination among crew members. A new mental framework for a performing crew was developed and tested through four case studies. This framework ensured similar team performance as the one provided by task micro-scheduling in planning software. It also allowed evaluation of the effect of individual coordination within the crew on the crew's productivity. Using design information, a list of micro-activities/tasks and their predecessors was automatically generated for each piece of lumber in the four wood frames. The task precedence was generated by applying elementary geometrical and technological reasoning to each frame. Then, the duration of each task was determined based on observations from videotaped activities. Primavera's (P6) resource leveling rules were used to calculate the sequencing of tasks and the minimum duration of the whole activity for various crew sizes. The results showed quick convergence towards the minimum production time and allowed to use information from Building Information Models (BIM) to automatically establish the optimal crew sizes for frames. Late Start (LS) leveling priority rule gave the shortest duration in every case. However, the logic of LS tasks rule is too complex to be conveyed to the framing crew. Therefore, the new mental framework of a well performing framer was developed and tested to ensure high coordination. This mental framework, based on five simple rules, can be easily taught to the crew and ensures a crew productivity congruent with the one provided by the LS logic. The case studies indicate that once the worst framer in the crew surpasses the limit of 11% deviation from applying the said five rules, every additional percent of deviation reduces the productivity of the whole crew by about 4%.
ContributorsMaghiar, Marcel M (Author) / Wiezel, Avi (Thesis advisor) / Mitropoulos, Panagiotis (Committee member) / Cooke, Nancy J. (Committee member) / Arizona State University (Publisher)
Created2011
Description
Detecting anatomical structures, such as the carina, the pulmonary trunk and the aortic arch, is an important step in designing a CAD system of detection Pulmonary Embolism. The presented CAD system gets rid of the high-level prior defined knowledge to become a system which can easily extend to detect other anatomic structures. The system is based on a machine learning algorithm --- AdaBoost and a general feature --- Haar. This study emphasizes on off-line and on-line AdaBoost learning. And in on-line AdaBoost, the thesis further deals with extremely imbalanced condition. The thesis first reviews several knowledge-based detection methods, which are relied on human being's understanding of the relationship between anatomic structures. Then the thesis introduces a classic off-line AdaBoost learning. The thesis applies different cascading scheme, namely multi-exit cascading scheme. The comparison between the two methods will be provided and discussed. Both of the off-line AdaBoost methods have problems in memory usage and time consuming. Off-line AdaBoost methods need to store all the training samples and the dataset need to be set before training. The dataset cannot be enlarged dynamically. Different training dataset requires retraining the whole process. The retraining is very time consuming and even not realistic. To deal with the shortcomings of off-line learning, the study exploited on-line AdaBoost learning approach. The thesis proposed a novel pool based on-line method with Kalman filters and histogram to better represent the distribution of the samples' weight. Analysis of the performance, the stability and the computational complexity will be provided in the thesis. Furthermore, the original on-line AdaBoost performs badly in imbalanced conditions, which occur frequently in medical image processing. In image dataset, positive samples are limited and negative samples are countless. A novel Self-Adaptive Asymmetric On-line Boosting method is presented. The method utilized a new asymmetric loss criterion with self-adaptability according to the ratio of exposed positive and negative samples and it has an advanced rule to update sample's importance weight taking account of both classification result and sample's label. Compared to traditional on-line AdaBoost Learning method, the new method can achieve far more accuracy in imbalanced conditions.
ContributorsWu, Hong (Author) / Liang, Jianming (Thesis advisor) / Farin, Gerald (Committee member) / Ye, Jieping (Committee member) / Arizona State University (Publisher)
Created2011
Description
Writing scientific explanations is increasingly important, and today's students must have the ability to navigate the writing process to create a persuasive scientific explanation. One aspect of the writing process is receiving feedback before submitting a final draft. This study examined whether middle school students benefit more in the writing process from receiving peer feedback or teacher feedback on rough drafts of scientific explanations. The study also looked at whether males and females reacted differently to the treatment groups. And it examined if content knowledge and the written scientific explanations were correlated. The study looked at 38 sixth and seventh-grade students throughout a 7-week earth science unit on earth systems. The unit had six lessons. One lesson introduced the students to writing scientific explanations, and the other five were inquiry-based content lessons. They wrote four scientific explanations throughout the unit of study and received feedback on all four rough drafts. The sixth-graders received teacher feedback on each explanation and the seventh-graders received peer-feedback after learning how to give constructive feedback. The students also took a multiple-choice pretest/posttest to evaluate content knowledge. The analyses showed that there was no significant difference between the group receiving peer feedback and the group receiving teacher feedback on the final drafts of the scientific explanations. There was, however, a significant effect of practice on the scores of the scientific explanations. Students wrote significantly better with each subsequent scientific explanation. There was no significant difference between males and females based on the treatment they received. There was a significant correlation between the gain in pretest to posttest scores and the scientific explanations and a significant correlation between the posttest scores and the scientific explanations. Content knowledge and written scientific explanations are related. Students who wrote scientific explanations had significant gains in content knowledge.
ContributorsLange, Katie (Author) / Baker, Dale (Thesis advisor) / Megowan, Colleen (Committee member) / Middleton, James (Committee member) / Arizona State University (Publisher)
Created2011
Description
ABSTRACT Many foster children experience numerous placements while in out-of-home care; some up to fifteen in an 18 month period (Newton, Litrownik, & Landsverk, 2000). Placement stability is important for children to find permanent families, and for social, emotional and educational development of children. This study used the National Survey of Child and Adolescent Well-being (NSCAW) data set to examine foster child and caregiver characteristics, and the caregiver-child relationship as a predictor of placement stability in the long term foster care general sample. Logistic regression was performed with the Complex Samples add-on to appropriately weight the NSCAW sampling. Children who were placed in foster homes or kinship homes and who had not been returned home at the Wave 3 interview were included in the study. The sample consisting of 562 children was divided into three groups based on age: Early Group 1, childhood ages 1to 5, group 1;Group 2, Middle childhood ages 6 to 10, group 2; Group 3, Adolescence ages 11 to 18, group 3. Results are consistent with previous studies in that children in early childhood and middle childhood who were placed in foster homes were 83% and 87% less likely to achieve placement stability than children in kinship homes, respectively. In early childhood, each additional household member reduced the odds of achieving placement stability by 35%.The caregiver-child relationship did not predict placement stability.
ContributorsO'Neill, Marissa (Author) / Risley-Curtiss, Christina (Thesis advisor) / Ayün, Cecilia (Committee member) / Williams, Lela (Committee member) / Arizona State University (Publisher)
Created2011
Description
The photovoltaic (PV) modules are primarily characterized for their performance with respect to incident irradiance and operating temperature. This work deals with data collection and automation of data processing for the performance and thermal characterizations of PV modules. This is a two-part thesis: The primary part (part-1) deals with the software automation to generate performance matrix as per IEC 61853-1 standard using MPPT (maximum power point tracking) data at the module or system level; the secondary part (part-2) deals with the software automation to predict temperature of rooftop PV modules using the thermal model coefficients generated in the previous studies of the Photovoltaic Reliability Laboratory (PRL). Part 1: The IEC 61853-1 standard published in January 2011 specifies the generation of a target performance matrix of photovoltaic (PV) modules at various temperatures and irradiance levels. In a conventional method, this target matrix is generated using all the data points of several measured I-V curves and the translation procedures defined in IEC 60891 standard. In the proposed method, the target matrix is generated using only three commonly field measured parameters: Module temperature, Incident irradiance and MPPT (Maximum Peak Power Tracking) value. These parameters are loaded into the programmed Excel file and with a click of a button, IEC 61853-1 specified Pmppt matrix is displayed on the screen in about thirty seconds. Part 2: In a previous study at PRL, an extensive thermal model to predict operating temperature of rooftop PV modules was developed with a large number of empirical monthly coefficients for ambient temperature, irradiance and wind speed. Considering that there is large number of coefficients for each air gap of rooftop modules, it became necessary to automate the entire data processing to predict the temperature of rooftop PV modules at different air gaps. This part of the work was dedicated to automatically predict the temperature of rooftop modules at different air gaps for any month in a year just using only four input parameters: Month, Irradiance, Ambient temperature and Wind speed.
ContributorsKoka, Kartheek (Author) / Tamizhmani, Govindasamy (Thesis advisor) / Rogers, Bradley (Committee member) / Macia, Narciso F. (Committee member) / Arizona State University (Publisher)
Created2011
Description
The constructs of compliance and temperament play an important role in children's school liking and engagement, and these constructs may differ between typically-developing children and children with autism because of the deficits associated with autism. The present study examined group differences among temperament, parent and child behaviors in a compliance context, and school liking and how these processes related to each other. This was the first study to examine school liking in children with high functioning autism and to explore the associations among school liking, temperament, and compliance in this population. Participants included children with high functioning autism (n = 20) and typically-developing children (n = 20) matched on language and mental age, and their parents. Compliance to a parent was observed in a laboratory setting, and temperament and school liking data were collected using parent-report measures. The findings revealed that children with autism had significantly lower Effortful Control (EC) and school liking scores than typically-developing children. However, there were no group differences in compliance, and no significant relation was found between temperament and compliance. Additionally, school liking scores were related to compliance and EC. These findings are discussed with respect to implications for potential future research and use of interventions for children with high functioning autism.
ContributorsInglese, Crystal (Author) / Jahromi, Laudan B (Thesis advisor) / Spinrad, Tracy (Committee member) / Sullivan, Amanda (Committee member) / Arizona State University (Publisher)
Created2011
Description
This study presents a structural model of coping with dating violence. The model integrates abuse frequency and solution attribution to determine a college woman's choice of coping strategy. Three hundred, twenty-four undergraduate women reported being targets of some physical abuse from a boyfriend and responded to questions regarding the abuse, their gender role beliefs, their solution attribution and the coping behaviors they executed. Though gender role beliefs and abuse severity were not significant predictors, solution attribution mediated between frequency of the abuse and coping. Abuse frequency had a positive effect on external solution attribution and external solution attribution had a positive effect on the level of use of active coping, utilization of social support, denial and acceptance.
ContributorsBapat, Mona (Author) / Tracey, Terence J.G. (Thesis advisor) / Bernstein, Bianca (Committee member) / Green, Samuel (Committee member) / Arizona State University (Publisher)
Created2011
Description
The evolution of single hairpin vortices and multiple interacting hairpin vortices are studied in direct numerical simulations of channel flow at Re-tau=395. The purpose of this study is to observe the effects of increased Reynolds number and varying initial conditions on the growth of hairpins and the conditions under which single hairpins autogenerate hairpin packets. The hairpin vortices are believed to provide a unified picture of wall turbulence and play an important role in the production of Reynolds shear stress which is directly related to turbulent drag. The structures of the initial three-dimensional vortices are extracted from the two-point spatial correlation of the fully turbulent direct numerical simulation of the velocity field by linear stochastic estimation and embedded in a mean flow having the profile of the fully turbulent flow. The Reynolds number of the present simulation is more than twice that of the Re-tau=180 flow from earlier literature and the conditional events used to define the stochastically estimated single vortex initial conditions include a number of new types of events such as quasi-streamwise vorticity and Q4 events. The effects of parameters like strength, asymmetry and position are evaluated and compared with existing results in the literature. This study then attempts to answer questions concerning how vortex mergers produce larger scale structures, a process that may contribute to the growth of length scale with increasing distance from the wall in turbulent wall flows. Multiple vortex interactions are studied in detail.
ContributorsParthasarathy, Praveen Kumar (Author) / Adrian, Ronald (Thesis advisor) / Huang, Huei-Ping (Committee member) / Herrmann, Marcus (Committee member) / Arizona State University (Publisher)
Created2011
Description
Action language C+ is a formalism for describing properties of actions, which is based on nonmonotonic causal logic. The definite fragment of C+ is implemented in the Causal Calculator (CCalc), which is based on the reduction of nonmonotonic causal logic to propositional logic. This thesis describes the language of CCalc in terms of answer set programming (ASP), based on the translation of nonmonotonic causal logic to formulas under the stable model semantics. I designed a standard library which describes the constructs of the input language of CCalc in terms of ASP, allowing a simple modular method to represent CCalc input programs in the language of ASP. Using the combination of system F2LP and answer set solvers, this method achieves functionality close to that of CCalc while taking advantage of answer set solvers to yield efficient computation that is orders of magnitude faster than CCalc for many benchmark examples. In support of this, I created an automated translation system Cplus2ASP that implements the translation and encoding method and automatically invokes the necessary software to solve the translated input programs.
ContributorsCasolary, Michael (Author) / Lee, Joohyung (Thesis advisor) / Ahn, Gail-Joon (Committee member) / Baral, Chitta (Committee member) / Arizona State University (Publisher)
Created2011
Description
The high penetration of photovoltaic (PV) both at the utility and at the distribu-tion levels, has raised concerns about the reliability of grid-tied inverters of PV power systems. Inverters are generally considered as the weak link in PV power systems. The lack of a dedicated qualification/reliability standard for PV inverters is a main barrier in realizing higher level of confidence in reliability. Development of a well-accepted design qualification standard specifically for PV inverters will help pave the way for significant improvement in reliability and performance of inverters across the entire industry. The existing standards for PV inverters such as UL 1741 and IEC 62109-1 primarily focus on safety. IEC 62093 discusses inverter qualification but it includes all the balance of sys-tem components and therefore not specific to PV inverters. There are other general stan-dards for distributed generators including the IEEE1547 series of standards which cover major concerns like utility integration but they are not dedicated to PV inverters and are not written from a design qualification point of view. In this thesis, some of the potential requirements for a design qualification standard for PV inverters are addressed. The IEC 62093 is considered as a guideline and the possible inclusions in the framework for a dedicated design qualification standard of PV inverter are discussed. The missing links in existing PV inverter related standards are identified by performing gap analysis. Dif-ferent requirements of small residential inverters compared to large utility-scale systems, and the emerging requirements on grid support features are also considered. Electric stress test is found to be the key missing link and one of the electric stress tests, the surge withstand test is studied in detail. The use of the existing standards for surge withstand test of residential scale PV inverters is investigated and a method to suitably adopt these standards is proposed. The proposed method is studied analytically and verified using simulation. A design criterion for choosing the switch ratings of the inverter that can per-form reliably under the surge environment is derived.
ContributorsAlampoondi Venkataramanan, Sai Balasubramanian (Author) / Ayyanar, Raja (Thesis advisor) / Vittal, Vijay (Committee member) / Heydt, Gerald (Committee member) / Arizona State University (Publisher)
Created2011