Multiobjective analysis for the design and control of an electromagnetic valve actuator

The electromagnetic valve actuator can deliver much improved fuel efficiency and reduced emissions in spark ignition (SI) engines owing to the potential for variable valve timing when compared with cam-operated, or conventional, variable valve strategies. The possibility exists to reduce pumping losses by throttle-free operation, along with closed-valve engine braking. However, further development is required to make the technology suitable for accept- ance into the mass production market. This paper investigates the application of multiobjective optimization techniques to the conflicting objective functions inherent in the operation of such a device. The techniques are utilized to derive the optimal force–displacement characteristic for the solenoid actuator, along with its controllability and dynamic/steady state performance

Young Measures Generated by Ideal Incompressible Fluid Flows

In their seminal paper "Oscillations and concentrations in weak solutions of the incompressible fluid equations", R. DiPerna and A. Majda introduced the notion of measure-valued solution for the incompressible Euler equations in order to capture complex phenomena present in limits of approximate solutions, such as persistence of oscillation and development of concentrations. Furthermore, they gave several explicit examples exhibiting such phenomena. In this paper we show that any measure-valued solution can be generated by a sequence of exact weak solutions. In particular this gives rise to a very large, arguably too large, set of weak solutions of the incompressible Euler equations.Comment: 35 pages. Final revised version. To appear in Arch. Ration. Mech. Ana

Improved thermal isolation of silicon suspended platforms for an all-silicon thermoelectric microgenerator based on large scale integration of Si nanowires as thermoelectric material

Special suspended micro-platforms have been designed as a part of silicon compatible planar thermoelectric microgenerators. Bottom-up grown silicon nanowires are going to bridge in the future such platforms to the surrounding silicon bulk rim. They will act as thermoelectric material thus configuring an all-silicon thermoelectric device. In the new platform design other additional bridging elements (usually auxiliary support silicon beams) are substituted by low conductance thin film dielectric membranes in order to maximize the temperature difference developed between both areas. These membranes follow a sieve-like design that allows fabricating them with a short additional wet anisotropic etch step. © Published under licence by IOP Publishing Ltd.Peer ReviewedPostprint (published version

Rank-(n – 1) convexity and quasiconvexity for divergence free fields

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Monoenergetic proton beams accelerated by a radiation pressure driven shock

High energy ion beams (> MeV) generated by intense laser pulses promise to be viable alternatives to conventional ion beam sources due to their unique properties such as high charge, low emittance, compactness and ease of beam delivery. Typically the acceleration is due to the rapid expansion of a laser heated solid foil, but this usually leads to ion beams with large energy spread. Until now, control of the energy spread has only been achieved at the expense of reduced charge and increased complexity. Radiation pressure acceleration (RPA) provides an alternative route to producing laser-driven monoenergetic ion beams. In this paper, we show the interaction of an intense infrared laser with a gaseous hydrogen target can produce proton spectra of small energy spread (~ 4%), and low background. The scaling of proton energy with the ratio of intensity over density (I/n) indicates that the acceleration is due to the shock generated by radiation-pressure driven hole-boring of the critical surface. These are the first high contrast mononenergetic beams that have been theorised from RPA, and makes them highly desirable for numerous ion beam applications

Metabolic factors in obesity

Obesity has a rising prevalence in children and adolescents, affecting 30% of the paediatric population in Portugal. Leptin is an important hormone involved in the pathogenesis of obesity and has been under investigation as a risk marker for future complications. AIMS: 1. To evaluate the relation between serum leptin levels and body mass index (BMI) and height. 2. To compare leptin levels in obese and non-obese children. 3. To evaluate the relation between leptin levels and insulin resistance index. METHODS: Cross-sectional study, using a sample of 70 obese children and a control group of 53 non-obese children. Obesity was defined as BMI standard deviation > 2 for age and sex. In the obese group we assessed sex, age, BMI SDS and height SDS for age and sex, and serum levels of glucose, insulin and leptin. In the control group were obtained BMI SDS and height SDS for age and sex and leptin levels. Data were analysed using SPSS 12. RESULTS: The mean age of obese and non-obese children was 10.3 +/- 2.9 versus 10.9 +/- 3.5 years. In the obese group, 32 (45.7%) were boys versus 18 (31.0%) in the non-obese group. BMI SDS in the obese group was 3.12 +/- 0.60 versus 0.20 +/- 0.99 in the non-obese group (p < 0.001). Leptin levels showed a positive correlation with BMI SDS (r = 0.69; p < 0.001) and height SDS (r = 0.31; p < 0.001). When comparing leptin levels between obese and non-obese groups, we found a significant difference in boys (50.7 +/- 27.3 versus 7.0 +/- 6.8 ng/ml; p < 0.001) and in girls (57.6 +/- 25.5 versus 16.5 +/- 10.3 ng/ml; p < 0.001). In the nonobese group, leptin levels were lower in boys. This difference was not seen in the obese group. Leptin showed a positive correlation with insulin resistance index in boys (r = 0.45, p = 0.05), but not in girls. CONCLUSIONS: This study has confirmed a positive correlation between leptin levels and BMI SDS. In obese children elevated leptin is associated with central resistance to its action. The positive correlation of leptin with insulin resistance index may suggest a major role of leptin in insulin resistance.info:eu-repo/semantics/publishedVersio

Finding SQL Injection and Cross Site Scripting Vulnerabilities with Diverse Static Analysis Tools

The use of Static Analysis Tools (SATs) is mandatory when developing secure software and searching for vulnerabilities in legacy software. However, the performance of the various SATs concerning the detection of vulnerabilities and false alarm rate is usually unknown and depends on many factors. The simultaneous use of several tools should increase the detection capabilities, but also the number of false alarms. In this paper, we study the problem of combining several SATs to best meet the developer needs. We present results of analyzing the performance of diverse static analysis tools, based on a previously published dataset that resulted from the use of five diverse SATs to find two types of vulnerabilities, namely SQL Injections (SQLi) and Cross-Site Scripting (XSS), in 132 plugins of the WordPress Content Management System (CMS). We present the results based on well-established measures for binary classifiers, namely sensitivity and specificity for all possible diverse combinations that can be constructed using these 5 SAT tools. We then provide empirically supported guidance on which combinations of SAT tools provide the most benefits for detecting vulnerabilities with low false positive rates