Multi-split configuration design for fluid-based thermal management systems

High power density systems require efficient cooling to maintain their thermal performance. Despite this, as systems get larger and more complex, human practice and insight may not suffice to determine the desired thermal management system designs. To this end, a framework for automatic architecture exploration is presented in this article for a class of single-phase, multi-split cooling systems. For this class of systems, heat generation devices are clustered based on their spatial information, and flow-split are added only when required and at the location of heat devices. To generate different architectures, candidate architectures are represented as graphs. From these graphs, dynamic physics models are created automatically using a graph-based thermal modeling framework. Then, an optimal fluid flow distribution problem is solved by addressing temperature constraints in the presence of exogenous heat loads to achieve optimal performance. The focus in this work is on the design of general multi-split heat management systems. The architectures discussed here can be used for various applications in the domain of configuration design. The multi-split algorithm can produce configurations where splitting can occur at any of the vertices. The results presented include 3 categories of cases and are discussed in detail.Comment: 11 pages, 18 figure

Advancing Fluid-Based Thermal Management Systems Design: Leveraging Graph Neural Networks for Graph Regression and Efficient Enumeration Reduction

In this research, we developed a graph-based framework to represent various aspects of optimal thermal management system design, with the aim of rapidly and efficiently identifying optimal design candidates. Initially, the graph-based framework is utilized to generate diverse thermal management system architectures. The dynamics of these system architectures are modeled under various loading conditions, and an open-loop optimal controller is employed to determine each system's optimal performance. These modeled cases constitute the dataset, with the corresponding optimal performance values serving as the labels for the data. In the subsequent step, a Graph Neural Network (GNN) model is trained on 30% of the labeled data to predict the systems' performance, effectively addressing a regression problem. Utilizing this trained model, we estimate the performance values for the remaining 70% of the data, which serves as the test set. In the third step, the predicted performance values are employed to rank the test data, facilitating prioritized evaluation of the design scenarios. Specifically, a small subset of the test data with the highest estimated ranks undergoes evaluation via the open-loop optimal control solver. This targeted approach concentrates on evaluating higher-ranked designs identified by the GNN, replacing the exhaustive search (enumeration-based) of all design cases. The results demonstrate a significant average reduction of over 92% in the number of system dynamic modeling and optimal control analyses required to identify optimal design scenarios.Comment: 13 pages, 17 figure

Extracting Design Knowledge from Optimization Data: Enhancing Engineering Design in Fluid Based Thermal Management Systems

As mechanical systems become more complex and technological advances accelerate, the traditional reliance on heritage designs for engineering endeavors is being diminished in its effectiveness. Considering the dynamic nature of the design industry where new challenges are continually emerging, alternative sources of knowledge need to be sought to guide future design efforts. One promising avenue lies in the analysis of design optimization data, which has the potential to offer valuable insights and overcome the limitations of heritage designs. This paper presents a step toward extracting knowledge from optimization data in multi-split fluid-based thermal management systems using different classification machine learning methods, so that designers can use it to guide decisions in future design efforts. This approach offers several advantages over traditional design heritage methods, including applicability in cases where there is no design heritage and the ability to derive optimal designs. We showcase our framework through four case studies with varying levels of complexity. These studies demonstrate its effectiveness in enhancing the design of complex thermal management systems. Our results show that the knowledge extracted from the configuration design optimization data provides a good basis for more general design of complex thermal management systems. It is shown that the objective value of the estimated optimal configuration closely approximates the true optimal configuration with less than 1 percent error, achieved using basic features based on the system heat loads without involving the corresponding optimal open loop control (OLOC) features. This eliminates the need to solve the OLOC problem, leading to reduced computation costs.Comment: 13 pages, 20 figure

Patterns of pneumococcal vaccination and revaccination in elderly and non-elderly adults: a Vaccine Safety Datalink study

<p>Abstract</p> <p>Background</p> <p>Pneumococcal polysaccharide vaccine (PPV) is recommended for all adults 65 years of age and older and for younger adults with high-risk conditions. While data from national surveys provide information on the proportion of adults 65 years of age and older reporting ever receipt of PPV they do not collect more detailed information, such as age at vaccination or the total number of vaccinations received. In addition, there is relatively little information available on PPV coverage in younger adults with chronic conditions. To assess contemporary patterns of pneumococcal vaccination and revaccination of adults, we conducted a cross-sectional study of adults enrolled in medical care organizations (MCOs) participating in the Vaccine Safety Datalink project.</p> <p>Methods</p> <p>The study population included 1.5 million adults 25 years of age and older enrolled in the four participating MCOs on December 1, 2006. PPVs administered to members of the study population prior to that date were identified from computerized immunization registries maintained by the MCOs.</p> <p>Results</p> <p>Among the general population of adults 25 through 64 years of age, vaccine coverage increased from 2% in the 25–29 year old age-group to 26% in the 60–64 year old age-group. In all age-groups, coverage was substantially higher in persons defined as having a chronic high risk condition. This was particularly true for diabetes mellitus, with vaccine coverage of over 50% in the lower age-groups and 75% in those 60–64 years of age. Among adults 65 years of age and older, 82% had received at least one PPV and 18% had received two or more PPVs.</p> <p>Conclusion</p> <p>We found higher levels of PPV coverage among adults 65 years of age and older and among younger adults with diabetes mellitus than reported by national surveys and for those groups PPV coverage approached the <it>Healthy People 2010 </it>national objectives. These results suggest that achieving those objectives for PPV is possible and that high vaccination coverage may be facilitated by vaccine tracking and reminder systems.</p

Do adults with high functioning autism or Asperger Syndrome differ in empathy and emotion recognition?

The present study examined whether adults with high functioning autism (HFA) showed greater difficulties in (i) their self-reported ability to empathise with others and/or (ii) their ability to read mental states in others’ eyes than adults with Asperger syndrome (AS). The Empathy Quotient (EQ) and ‘Reading the Mind in the Eyes’ Test (Eyes Test) were compared in 43 adults with AS and 43 adults with HFA. No significant difference was observed on EQ score between groups, while adults with AS performed significantly better on the Eyes Test than those with HFA. This suggests that adults with HFA may need more support, particularly in mentalizing and complex emotion recognition, and raises questions about the existence of subgroups within autism spectrum conditions

Growth characteristics in individuals with osteogenesis imperfecta in North America: results from a multicenter study.

PurposeOsteogenesis imperfecta (OI) predisposes people to recurrent fractures, bone deformities, and short stature. There is a lack of large-scale systematic studies that have investigated growth parameters in OI.MethodsUsing data from the Linked Clinical Research Centers, we compared height, growth velocity, weight, and body mass index (BMI) in 552 individuals with OI. Height, weight, and BMI were plotted on Centers for Disease Control and Prevention normative curves.ResultsIn children, the median z-scores for height in OI types I, III, and IV were -0.66, -6.91, and -2.79, respectively. Growth velocity was diminished in OI types III and IV. The median z-score for weight in children with OI type III was -4.55. The median z-scores for BMI in children with OI types I, III, and IV were 0.10, 0.91, and 0.67, respectively. Generalized linear model analyses demonstrated that the height z-score was positively correlated with the severity of the OI subtype (P &lt; 0.001), age, bisphosphonate use, and rodding (P &lt; 0.05).ConclusionFrom the largest cohort of individuals with OI, we provide median values for height, weight, and BMI z-scores that can aid the evaluation of overall growth in the clinic setting. This study is an important first step in the generation of OI-specific growth curves

Trends in thrombolytic use for ischemic stroke in the United States

BACKGROUND: Although recombinant tissue plasminogen activator (tPA) improves outcomes from ischemic stroke, prior studies have found low rates of administration. Recent guidelines and regulatory agencies have advocated for increased tPA administration in appropriate patients, but it is unclear how many patients actually receive tPA. OBJECTIVE: To determine whether national rates of tPA use for ischemic stroke have increased over time. METHODS: We identified all patients with a primary diagnosis of ischemic stroke from years 2001 to 2006 in the National Hospital Discharge Survey (NHDS), a nationally representative sample of inpatient hospitalizations, and searched for procedure codes for intravenous thrombolytic administration. Clinical and demographic factors were obtained from the survey and multivariable logistic regression used to identify independent predictors associated with thrombolytic use. RESULTS: Among the 22,842 patients hospitalized with ischemic stroke, tPA administration rates increased from 0.87% in 2001 to 2.40% in 2006 ( P < 0.001 for trend). Older patients were less likely to receive tPA (adjusted odds ratio [OR] and 95% confidence interval [CI]; 0.4 [0.3-0.6] for patients ≥80 years vs. <60 years), as were African American patients (0.4 [0.3-0.7]). Larger hospitals were more likely to administer tPA (3.3 [2.0-5.6] in hospitals with at least 300 beds compared to those with 6-99 beds). CONCLUSIONS: Although tPA administration for ischemic stroke has increased nationally in recent years, the overall rate of use remains very low. Larger hospitals were more likely to administer tPA. Further efforts to improve appropriate administration of tPA should be encouraged, particularly as the acceptable time-window for using tPA widens. Journal of Hospital Medicine 2010. © 2010 Society of Hospital Medicine.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78061/1/689_ftp.pd

Frequency of medically attended adverse events following tetanus and diphtheria toxoid vaccine in adolescents and young adults: a Vaccine Safety Datalink study

<p>Abstract</p> <p>Background</p> <p>Local reactions are the most commonly reported adverse events following tetanus and diphtheria toxoid (Td) vaccine and the risk of local reactions may increase with number of prior Td vaccinations.</p> <p>Methods</p> <p>To estimate the risk of medically attended local reactions following Td vaccination in adolescents and young adults we conducted a six-year retrospective cohort study assessing 436,828 Td vaccinations given to persons 9 through 25 years of age in the Vaccine Safety Datalink population from 1999 through 2004.</p> <p>Results</p> <p>Overall, the estimated risk of a medically attended local reaction was 3.6 events per 10,000 Td vaccinations. The lowest risk (2.8 events per 10,000 vaccinations) was found in the 11 to 15 year old age group. In comparison with that group, the event risks were significantly higher in both the 9 to 10 and 21 to 25 year old age groups. The risk of a local reaction was significantly higher in persons who had received another tetanus and diphtheria toxoid containing vaccine (TDCV) in the previous five years (incidence rate ratio, 2.9; 95% confidence interval, 1.2 to 7.2). Twenty-eight percent of persons with a local reaction to Td vaccine were prescribed antibiotics.</p> <p>Conclusion</p> <p>Medically attended local reactions were uncommon following Td vaccination. The risk of those reactions varied by age and by prior receipt of TDCVs. These findings provide a point of reference for future evaluations of the safety profile of newer vaccines containing tetanus or diphtheria toxoid.</p

mRNA expression of the DNA replication-initiation proteins in epithelial dysplasia and squamous cell carcinoma of the tongue

<p>Abstract</p> <p>Background</p> <p>The tongue squamous cell carcinomas (SCCs) are characterized by high mitotic activity, and early detection is desirable. Overexpression of the DNA replication-initiation proteins has been associated with dysplasia and malignancy. Our aim was to determine whether these proteins are useful biomarkers for assessing the development of tongue SCC.</p> <p>Methods</p> <p>We analyzed the mRNA expression of CDC6, CDT1, MCM2 and CDC45 in formalin-fixed, paraffin-embedded benign and malignant tongue tissues using quantitative real-time PCR followed by statistical analysis.</p> <p>Results</p> <p>We found that the expression levels are significantly higher in malignant SCC than mild precancerous epithelial dysplasia, and the expression levels in general increase with increasing grade of precancerous lesions from mild, moderate to severe epithelial dysplasia. CDC6 and CDC45 expression is dependent of the dysplasia grade and lymph node status. CDT1 expression is higher in severe dysplasia than in mild and moderate dysplasia. MCM2 expression is dependent of the dysplasia grade, lymph node status and clinical stage. The expression of the four genes is independent of tumor size or histological grade. A simple linear regression analysis revealed a linear increase in the mRNA levels of the four genes from the mild to severe dysplasia and SCC. A strong association was established between CDC6 and CDT1, and between MCM2 and CDC45 expression. The nonparametric receiver operating characteristic analysis suggested that MCM2 and CDC45 had a higher accuracy than CDC6 and CDT1 for distinguishing dysplasia from tongue SCC.</p> <p>Conclusion</p> <p>These proteins can be used as biomarkers to distinguish precancerous dysplasia from SCC and are useful for early detection and diagnosis of SCC as an adjunct to clinicopathological parameters.</p