STUDI REGIM ALIRAN FLUIDA DAN PENENTUAN HEAD LOSS AKIBAT GESEKAN PADA INSTALASI PERPIPAAN

Instalasi perpipaan dalam industry merupakan sistem keteknikan memegang perananan penting yang berfungsi untuk mengalirkan  air, minyak dan gas dari satu titik ke titik lain melalui semua komponen yang tercakup didalamnya. Sistem perpipaan terdiri dari pipa lurus, sambungan-sambungan, belokan katup-katup dan peralatan-peralatan instrumentasi yang harus bekerja secara optimal. Regim aliran fluida di dalam berbagai komponen perpipaan memberikan pengaruh terhadap aliran teristimewa pada dua parameter penting yaitu koefesien gesek dan kehilangan head. Tujuan penelitian ini adalah memantau sifat pergerakan fluida dalam rezim laminar dan turbulen dan menentukan nilai head loss sebagai fungsi debit dalam rezim laminar dan turbulen. Penelitian dilakukan pada pipa lurus berdiamater 4 inci dengan panjang total 10 meter, diameter 4 inci dengan satu belokan 90o. Penentuan hubungan kerugian head terhadap debit dilakukan melalui simulasi hidrodinamika, dimana kecepatan aliran divariasi dari 0,02 - 0,1 m/s, sesuai dengan debit Q = 10-52 liter/menit. Variasi kecepatan ini melewati regim aliran laminar dan turbulen yang diukur pada 4 penampang pada pipa lurus dan elbow. Hasil yang diperoleh menunjukan bahwa profil aliran pada setiap penampang berbeda-bada untuk nilai debit Q yang sama. Pada setiap penampang dengan variasi nilai debit Q, karakter nilai kerugian head meningkat dengan meningkatnya debit aliran Q dengan nilai berbeda pada setiap penampang, namun trend perubahannya mirip. Kondisi laminar terjadi pada Q <34 lit/menit dengan kerugian head hdl < 0,74x10-3 m,  transisi terjadi pada Q=34-36 lit/menit, dengan hdl = (0,74 -0,68)x10-3 m dan turbulen sepenuhnya pada Q>36 lit/menit dengan hdl > 0,74x10-3 m. Hal ini menujukan bahwa pada elbow atau belokan, aliran akan menjadi turbulen walaupun pada kecepatan yang rendah

An Equation of State of a Carbon-Fibre Epoxy Composite under Shock Loading

An anisotropic equation of state (EOS) is proposed for the accurate extrapolation of high-pressure shock Hugoniot (anisotropic and isotropic) states to other thermodynamic (anisotropic and isotropic) states for a shocked carbon-fibre epoxy composite (CFC) of any symmetry. The proposed EOS, using a generalised decomposition of a stress tensor [Int. J. Plasticity \textbf{24}, 140 (2008)], represents a mathematical and physical generalisation of the Mie-Gr\"{u}neisen EOS for isotropic material and reduces to this equation in the limit of isotropy. Although a linear relation between the generalised anisotropic bulk shock velocity $U^{A}_{s}$ and particle velocity $u_{p}$ was adequate in the through-thickness orientation, damage softening process produces discontinuities both in value and slope in the $U^{A}_{s}$-$u_{p}$ relation. Therefore, the two-wave structure (non-linear anisotropic and isotropic elastic waves) that accompanies damage softening process was proposed for describing CFC behaviour under shock loading. The linear relationship $U^{A}_{s}$-$u_{p}$ over the range of measurements corresponding to non-linear anisotropic elastic wave shows a value of $c^{A}_{0}$ (the intercept of the $U^{A}_{s}$-$u_{p}$ curve) that is in the range between first and second generalised anisotropic bulk speed of sound [Eur. Phys. J. B \textbf{64}, 159 (2008)]. An analytical calculation showed that Hugoniot Stress Levels (HELs) in different directions for a CFC composite subject to the two-wave structure (non-linear anisotropic elastic and isotropic elastic waves) agree with experimental measurements at low and at high shock intensities. The results are presented, discussed and future studies are outlined.Comment: 12 pages, 9 figure

The Early Husserl on Typicality

This paper presents and evaluates the early Husserl’s account of typicality. In the Logical Investigations, Husserl holds that the meaning of ordinary language (common) names is sensitive to typicality: this meaning depends on typical examples which vary in different contexts and are more or less similar to one another. This seems to entail that meanings, which according to Husserl are concepts, are “fluctuating” (schwankend) and vague. Prima facie, such a claim contravenes his theory of ideal meanings, or concepts, which are “fixed” (fest) and sharp. However, Husserl wants to save this theory. He claims that the fluctuation and vagueness in question are not to be found in the meaning itself, or the concept, but rather derive from the act of meaning. Thus, he apparently manages to make room for typicality in ordinary language while accepting only fixed and sharp meanings. After presenting Husserl’s theory, I evaluate it and ask whether he will still be committed, despite his own claims, to accepting prototype concepts to account for typicality in ordinary language

A school-based physical activity program to improve health and fitness in children aged 6–13 years ("Kinder-Sportstudie KISS"): study design of a randomized controlled trial [ISRCTN15360785]

BACKGROUND: Childhood obesity is the result of a long lasting imbalance between energy intake and energy expenditure. A major contributing factor is physical inactivity which is closely linked to bone health, cardiovascular disease risk, fitness and psychological factors. The school seems to provide an excellent setting to enhance levels of physical activity (PA). However, there is insufficient data from previous school-based intervention trials on how to enhance overall PA. It is also unknown whether an intervention aimed at increasing PA is effective in improving the children's health. The purpose of this paper is to outline the design of a school-based randomized, controlled trial (RCT) aiming to increase overall PA and to improve fitness and health in 6- to 13-year-old children. METHODS/DESIGN: 15 schools were randomized to the intervention (n = 9) or the control (n = 6) group, stratified by geographic region (urban vs. rural) and by age (1(st )and 5(th )grade). Participation was given for all children in the intervention group since in this group the intervention was part of the normal school curriculum. The intervention during one academic year consisted of: 1. two additional physical education classes per week given by trained physical education teachers adding up to a total of five PA classes per week, 2. short PA breaks (2–5 min each) during academic lessons, 3. PA home work, and 4. adaptation of recreational areas around the school. All children underwent anthropometric measurements, blood pressure assessment, fitness testing, measurement of PA and they filled out questionnaires. At least 70% of all children agreed to blood sampling and measurements of body composition and bone mineral measurements by dual energy x-ray absorptiometry. The primary endpoints of the study after one year were an increase in total PA by accelerometry, an increase in aerobic fitness measured by the 20 m shuttle run, a decrease in percent body fat derived from skinfold measurements and an increase in quality of life as assessed by the child health questionnaire in the intervention group compared to the control group. Secondary outcomes were overall fitness, differences in body composition including body fat distribution, cardiovascular risk factors, psychosocial health, bone mineral content and density of femur, lumbar spine and total body and food intake. DISCUSSION: Our preliminary data suggest that the children were representative of Swiss children with respect to sex, socio-demographic status, and body mass index. Short-term results can be expected by the beginning of 2007. We hypothesized that our intervention will lead to an increase in PA, fitness and overall health. Based on our data, we aim to provide important information regarding the influence of such an intervention on these outcome measures in school-aged children and to provide nationwide guidelines to improve PA in children

Targeting Signal Transduction Pathways in Metastatic Breast Cancer: A Comprehensive Review

This review summarizes some of the key signaling pathways involved in tumor progression and some of the novel therapies that are in development for the treatment of metastatic breast cancer patients

Beyond trastuzumab: novel therapeutic strategies in HER2-positive metastatic breast cancer

The use of trastuzumab, a monoclonal antibody that targets the human epidermal growth factor receptor 2 (HER2) alteration present in 25 to 30% of breast cancers, has been associated with improved survival outcomes in both the adjuvant and metastatic settings. However, despite the robust clinical efficacy of trastuzumab in HER2-positive metastatic breast cancer (MBC), primary and secondary resistance remains a clinical challenge. Although lapatinib has demonstrated modest activity in this setting, trials reported to date have yet to demonstrate improvements in overall survival with its use. Novel therapeutic strategies to circumvent trastuzumab resistance are warranted, and agents targeting the HER, vascular endothelial growth factor, heat shock protein 90, phosphoinositide 3 kinase/Akt/mammalian target of rapamycin, and insulin-like growth factor-1 receptor pathways represent rational approaches in the management of HER2-positive disease. In this review, early-phase and emerging trial data surrounding the use of these promising agents in HER2-positive MBC will be discussed