On the Application of Topology Optimisation Techniques to Thermal Management of Microelectronics Systems

In this paper, an autonomous thermal management design process based on a topological optimisation algorithm is presented. The numerical framework uses a finite element multiphysics solver to assess fluid flow and heat transfer, coupled with the Method of Moving Asymptotes approach for topology optimisation. The design framework is utilised to develop a copper heatsink for a simplified electronics package at two differing Reynolds numbers. In both cases, the final shape resembles a tree like structure rather than a more conventional fin structure

Modelling methodologies for quality assessment of 3D inkjet printed electronic products

Purpose of the Fraunhofer Direct Digital Manufacturing Conference is an intellectual exchange between researchers, enterprises and users of Additive Manufacturing technologies in order to gather the latest information about trends, progress, importance and the future potential of these technologies for industrial applications. The range of topics covers Product Development (incl. simulation, co-design, mass customization), Technologies (incl. bio-printing, hybrid processes, novel developments/visionary concepts, process chains for industrial production), Materials (incl. ceramics, bio-materials, multi-material approaches), Quality (incl. process/ part quality management) as well as further innovative and visionary approaches not fitting the range of topics above. Renowned international keynote speakers give insight into the latest trends and challenges in additive manufacturing in a variety of industry sectors, including biomedical, aerospace and automotive

Numerical analysis of droplet deposition in inkjet printed electronics assembly

In this paper, a computational approach for the analysis of microscale droplet impact dynamics is presented. The approach is intended to support a condition based monitoring system to enhance quality and reliability of inkjet printed electronics components. The Smoothed Particle Hydrodynamics (SPH) approach of Lucy and Gingold and Monaghan has been used as the basis for the model, with the δ-SPH terms of Marrone et al used to improve handling of the dynamic impact events and the gradient correction terms of Belytschko used to improve the accuracy of interface dynamics. Model validation has been performed through comparison against a macroscale dam break problem and through a microscale analysis designed to determine accurate surface tension-pressure behaviour based on the Young-Laplace relation. The model is used to assess impact of a single drop on a uniform surface and the three dimensional formation of multi-drop layers

Experimental investigation of open-ended microwave oven assisted encapsulation process

An open ended microwave oven is presented with improved uniform heating, heating rates and power conversion efficiency. This next generation oven produces more uniform EM fields in the evanescent region forming part of the heating area of the oven. These fields are vital for the rapid and uniform heating of various electromagnetically lossy materials. A fibre optic temperature sensor and an IR pyrometer are used to measure in situ and in real-time the temperature of the curing materials. An automatic computer controlled closed feedback loop measures the temperature in the curing material and drives the microwave components to obtain predetermined curing temperature cycles for efficient curing. Uniform curing of the lossy encapsulants is achieved with this oven with typical cure cycle of 270 seconds with a ramp rate of 1oC/s and a hold period of 2 minutes. Differential scanning calorimeter based measurement for the pulsed microwave based curing of the polymer dielectric indicates a ~ 100% degree of cure

SPH analysis of inkjet droplet impact dynamics

This paper presents a novel Smoothed Particle Hydrodynamics (SPH) framework for analysis of droplet impact dynamics in a 3D inkjet printing process. Results obtained are validated against experimentally derived high-speed imaging data. The numerical framework is based on the Smoothed Particle Hydrodynamics approach of Monaghan et al [1] which has been proven to be efficient and effective for analysis of dynamic fluid flow problems involving free surface interfaces. The SPH approach has been augmented through addition of the kernel gradient correction scheme proposed by Belytschko et al [2] and stabilization terms of Marrone et el [3]. This correction provides a more accurate approximation of the boundary forces including surface tension which dominate at typical inkjet droplet lengthscales (<100 µm). Analysis is expedited through adoption of the OpenACC programming paradigm to enable GPU based computation. Numerical analyses have been validated against analytical solutions, reference macroscale problems and through comparison with experimental high speed imaging data of the inkjet printing process. The experimental setup consisted of a Fuji Dimatix SL-128 inkjet printhead jetting an acrylate based 3D printing build material onto a glass substrate. Images of a single inkjet droplet impacting onto the glass slide were captured at a rate of 100,000 frames per second, with droplet diameter assessed using a weight test approach. Qualitative comparison of the numerical and experimental results showed a good agreement, indicating that the implemented framework is effective for analysis of the fluidic aspects of the printing process. The model is able to assist in tackling manufacturing issues that can detrimentally influence the quality of manufactured parts through provision of insight into the process

Economic burden of neural tube defects and impact of prevention with folic acid: a literature review

Neural tube defects (NTDs) are the second most common group of serious birth defects. Although folic acid has been shown to reduce effectively the risk of NTDs and measures have been taken to increase the awareness, knowledge, and consumption of folic acid, the full potential of folic acid to reduce the risk of NTDs has not been realized in most countries. To understand the economic burden of NTDs and the economic impact of preventing NTDs with folic acid, a systematic review was performed on relevant studies. A total of 14 cost of illness studies and 10 economic evaluations on prevention of NTDs with folic acid were identified. Consistent findings were reported across all of the cost of illness studies. The lifetime direct medical cost for patients with NTDs is significant, with the majority of cost being for inpatient care, for treatment at initial diagnosis in childhood, and for comorbidities in adult life. The lifetime indirect cost for patients with spina bifida is even greater due to increased morbidity and premature mortality. Caregiver time costs are also significant. The results from the economic evaluations demonstrate that folic acid fortification in food and preconception folic acid consumption are cost-effective ways to reduce the incidence and prevalence of NTDs. This review highlights the significant cost burden that NTDs pose to healthcare systems, various healthcare payers, and society and concludes that the benefits of prevention of NTDs with folic acid far outweigh the cost. Further intervention with folic acid is justified in countries where the full potential of folic acid to reduce the risk of NTDs has not been realized

Surviving pediatric intensive care: physical outcome after 3 months

Objective: This study investigated the prevalence and nature of physical and neurocognitive sequelae in pediatric intensive care unit ( PICU) survivors. Design and setting: Prospective follow-up study 3 months after discharge from a 14-bed tertiary PICU in The Netherlands. Patients and participants: The families of 250 previously healthy children unexpectedly admitted to the PICU were invited to visit the outpatient follow-up clinic for structured medical examination of the child 3 months after discharge; 186 patients were evaluated. Measurements and results: Pediatric Cerebral Performance Category ( PCPC) and Pediatric Overall Performance Category ( POPC) values were determined at PICU discharge, at the outpatient follow-up clinic, and retrospectively before admission to the PICU. We found that 69% of children had physical sequelae. In 30% of cases these were caused by a previously unknown illness and in 39% by acquired morbidity. In 8% of the children the acquired morbidity was related to complications from PICU procedures. Three months after discharge 77% of the children had normal PCPC scores and 31% had normal POPC scores. Conclusions: Our results indicate that PICU survival may be associated with substantial physical sequelae. Structured follow-up research, preferably by multicenter studies, is warranted in PICU survivor

Serum S100B levels after meningioma surgery: A comparison of two laboratory assays

<p>Abstract</p> <p>Background</p> <p>S100B protein is a potential biomarker of central nervous system insult. This study quantitatively compared two methods for assessing serum concentration of S100B.</p> <p>Methods</p> <p>A prospective, observational study performed in a single tertiary medical center. Included were fifty two consecutive adult patients undergoing surgery for meningioma that provided blood samples for determination of S100B concentrations. Eighty samples (40 pre-operative and 40 postoperative) were randomly selected for batch testing. Each sample was divided into two aliquots. These were analyzed by ELISA (Sangtec) and a commercial kit (Roche Elecsys^®) for S100B concentrations. Statistical analysis included regression modelling and Bland-Altman analysis.</p> <p>Results</p> <p>A parsimonious linear model best described the prediction of commercial kit values by those determined by ELISA (y = 0.045 + 0.277*x, x = ELISA value, R²= 0.732). ELISA measurements tended to be higher than commercial kit measurements. This discrepancy increased linearly with increasing S100B concentrations. At concentrations above 0.7 μg/L the paired measurements were consistently outside the limits of agreement in the Bland-Altman display. Similar to other studies that used alternative measurement methods, sex and age related differences in serum S100B levels were not detected using the Elecsys^®(p = 0.643 and 0.728 respectively).</p> <p>Conclusion</p> <p>Although a generally linear relationship exists between serum S100B concentrations measured by ELISA and a commercially available kit, ELISA values tended to be higher than commercial kit measurements particularly at concentrations over 0.7 μg/L, which are suggestive of brain injury. International standardization of commercial kits is required before the predictive validity of S100B for brain damage can be effectively assessed in clinical practice.</p

Thermal expansion of solid solutions Kr-CH4 at temperatures of liquid helium

A negative contribution of the CH4 impurity to the thermal expansion of the solution has been revealed in dilatometric studies of solid Kr+0.76% CH4, Kr+5.25% CH4 and Kr+10.5% CH4 solutions at 1-23 K. It is shown that the negative contribution results from changes in the occupancy of the ground state of the A-modifications of isolated CH4 molecules. Assuming that the CH4 impurity singles and clusters contribute to the thermal expansion independently, we can estimate their contributions. The contribution of the singles to the thermal expansion of the solid solution is negative. The energies of the first excitational rotational states were determined for singles and two-body and three-body clusters of CH4 molecules.Comment: 10 pages, 7 figure

Measuring Health Utilities in Children and Adolescents: A Systematic Review of the Literature.

BACKGROUND: The objective of this review was to evaluate the use of all direct and indirect methods used to estimate health utilities in both children and adolescents. Utilities measured pre- and post-intervention are combined with the time over which health states are experienced to calculate quality-adjusted life years (QALYs). Cost-utility analyses (CUAs) estimate the cost-effectiveness of health technologies based on their costs and benefits using QALYs as a measure of benefit. The accurate measurement of QALYs is dependent on using appropriate methods to elicit health utilities. OBJECTIVE: We sought studies that measured health utilities directly from patients or their proxies. We did not exclude those studies that also included adults in the analysis, but excluded those studies focused only on adults. METHODS AND FINDINGS: We evaluated 90 studies from a total of 1,780 selected from the databases. 47 (52%) studies were CUAs incorporated into randomised clinical trials; 23 (26%) were health-state utility assessments; 8 (9%) validated methods and 12 (13%) compared existing or new methods. 22 unique direct or indirect calculation methods were used a total of 137 times. Direct calculation through standard gamble, time trade-off and visual analogue scale was used 32 times. The EuroQol EQ-5D was the most frequently-used single method, selected for 41 studies. 15 of the methods used were generic methods and the remaining 7 were disease-specific. 48 of the 90 studies (53%) used some form of proxy, with 26 (29%) using proxies exclusively to estimate health utilities. CONCLUSIONS: Several child- and adolescent-specific methods are still being developed and validated, leaving many studies using methods that have not been designed or validated for use in children or adolescents. Several studies failed to justify using proxy respondents rather than administering the methods directly to the patients. Only two studies examined missing responses to the methods administered with respect to the patients' ages