A coupled finite-volume CFD solver for two-dimensional elasto-hydrodynamic lubrication problems with particular application to rolling element bearings

This paper describes a new computational fluid dynamics methodology for modelling elastohydrodynamic contacts. A finite-volume technique is implemented in the ‘OpenFOAM’ package to solve the Navier-Stokes equations and resolve all gradients in a lubricated rolling-sliding contact. The method fully accounts for fluid-solid interactions and is stable over a wide range of contact conditions, including pressures representative of practical rolling bearing and gear applications. The elastic deformation of the solid, fluid cavitation and compressibility, as well as thermal effects are accounted for. Results are presented for rolling-sliding line contacts of an elastic cylinder on a rigid flat to validate the model predictions, illustrate its capabilities, and identify some example conditions under which the traditional Reynolds-based predictions deviate from the full CFD solution

The influence of the preparation method of NiOx photocathodes on the efficiency of p-type dye-sensitised solar cells

Improving the efficiency of p-type dye-sensitized solar cells (DSCs) is an important part of the development of high performance tandem DSCs. The optimization of the conversion efficiency of p-DSCs could make a considerable contribution in the improvement of solar cells at a molecular level. Nickel oxide is the most widely used material in p-DSCs, due to its ease of preparation, chemical and structural stability, and electrical properties. However, improvement of the quality and conductivity of NiO based photocathodes needs to be achieved to bring further improvements to the solar cell efficiency. The subject of this review is to consider the effect of the preparation of NiO surfaces on their efficiency as photocathodes. (C) 2015 Elsevier B.V. All rights reserved

Heat flux evaluation in high temperature ring-on-ring contacts

A comprehensive methodology to investigate heat flux in a ring-on-ring tribometer is presented. Thermal fluxes under high contact pressures and temperature differences were evaluated through an experimental campaign and by a numerical procedure of inverse analysis applied to surface temperature measurements. An approximation of a two-dimensional time-dependent analytical solution for the temperature distribution was first developed and subsequently adapted to mimic the specific testing configuration characteristics; the problem was finally simplified to enable further inverse analysis. Experiments were performed using an innovative high temperature ring-on-ring tribometer. The evaluated contact heat transfer rates were reported as a function of normal load and temperature difference between the discs under steady-state conditions; the results reported here show that, in the present test configuration, the temperature difference has stronger influence than the applied load in terms of heat transfer induced by contact

Hubungan Kematangan Emosi Dan Kebahagiaan Pada Remaja Yang Mengalami Putus Cinta

Salah satu tugas perkembangan remaja adalah mulai mengenal lawan jenis dan jatuh cinta. Berbicara mengenai jatuh cinta pasti juga akan berbicara mengenai putus cinta. Menurut data statistic ditemukan factor utama yang menjadi alasan remaja bunuh diri adalah masalah percintaan. Oleh karena itu para remaja perlu memiliki kematangan emosi yang baik sebelum memutuskan untuk berpacaran karena dengan kematangan emosi yang baik remaja akan mampu mengendalikan segala bentuk emosi negatif yang muncul setelah berpisah dari mantan pacar dan mengedepankan emosi positif yang mampu memicu timbulnya kebahagiaan. Populasi dalam penelitian ini merupakan remaja dengan kategori usia 17-21 tahun yang pernah putus cinta maksimal 2 tahun yang lalu dengan jumlah sampel sebanyak 84 responden. Teknik analisis data yang digunakan adalah korelasi Product Moment Pearson dengan koefesien sebesar 0.721 dan P= 0,000 (p<0,05). Hasil penelitian menunjukkan bahwa ada hubungan yang sangat signifikan dengan arah hubungan positif antara kematangan emosi dan kebahagiaan pada remaja yang mengalami putus cinta, bahwa semakin tinggi kematangan emosi maka akan semakin tinggi pula kebahagiaan dan semakin rendah kematangan emosi maka akan semakin rendah kebahagiaan pada remaja yang mengalami putuscinta

Estimating the avoidable burden of certain modifiable risk factors in osteoporotic hip fracture using Generalized Impact Fraction (GIF) model in Iran

Backgrounds: The number of hip fractures, the most common complication of osteoporosis, has increased rapidly over the past decades. The goal of this study is to estimate the avoidable burden of certain modifiable risk factor of the condition using the Generalized Impact Fraction (GIF) model, which has been suggested and used by epidemiologists to overcome the drawbacks associated with the use of Attributable Fraction index. In addition to preventing a risk factor or the avoidable fraction of burden, this index can also calculate the change in the burden, when a risk factor is altered.Methods: International databases were searched through PubMed, CINAHLD, Embase using OVID and Google scholar. National resources were searched through IranDoc, IranMedex, SID and Journal sites. Other resources include abstract books and articles sent to the IOF congress. The following search strategy was used: (" Osteoporotic fracture" OR " Fragility Hip fracture" OR " Calcium" OR " vitamin D" OR " BMI" OR " lean body weight" OR " Physical activity" OR " exercise" OR " Smoke" ) AND (" prevalence" OR " incidence" OR " relative risk" ) and limited to " humans." Results: With regards to different scenarios already explained in modifying the studied risk factors, the greatest impact in reducing the prevalence of risk factors on osteoporotic hip fractures, was seen in low serum vitamin D levels, low physical activity and low intake of calcium and vitamin D, respectively. According to the fact that interventions for low serum vitamin D and low intake of calcium and vitamin D, are related to each other, it can be concluded that implementing interventions to change these two risk factors, in the easy, moderate and difficult scenarios, would result in approximately a 5%, 11% and 17% decrease in the burden of osteoporotic hip fractures, respectively. The addition of interventions addressing low physical activity in the easy, moderate and difficult scenarios, an 8%, 21% and 35% reduction in the burden of osteoporotic hip fractures would be reported, respectively.Conclusion: Improving serum vitamin D levels, recommending the consumption of calcium and vitamin D supplementations and advocating physical activity are the most effective interventions to reduce the risk of osteoporotic hip fractures. © 2013 Shahnazari et al; licensee BioMed Central Ltd

Sindrom Geriatri (Imobilitas, Instabilitas, Gangguan Intelektual, Inkontinensia, Infeksi, Malnutrisi, Gangguan Pendengaran)

Latar Belakang. Sindrom geriatri adalah serangkaian kondisi klinis pada orang tua yangdapat mempengaruhi kualitas hidup pasien dan dikaitkan dengan kecacatan. Tampilanklinis yang tidak khas sering membuat sindrom geriatri tidak terdiagnosis. Kasus. Tn. H,80 tahun, datang dengan keluhan sesak nafas yang baru pertama kali dialami.Inkontinensia alvi, inkontinensia urin, demensia, dan sulit berjalan sudah dirasakan pasiendalam 3 bulan. Dua hari sebelum masuk rumah sakit, pasien terjatuh dari kursi karenakondisi pasien yang lemah. Tidak ada riwayat khusus tentang penyakit yang pernahdialami pasien. Kesadaran compos mentis dengan tekanan darah 140/80 mmHg. Padaekstremitas bawah terdapat edema non pitting. Pemeriksaan laboratorium didapatkan Hb:11.5 g/dl, Ht : 35.6%, Albumin: 2.55, Serum Glutamic Oxaloacetic Transaminase: 84.3,Serum Glutamic Pyruvic Transaminase : 120.7, Ureum: 134.6, Kreatinin: 3.40.Penatalaksanaan pasien dilakukan berdasarkan prinsip pengobatan pada geriatri.Simpulan: Sindrom geriatri adalah suatu kondisi klinis, bukan penyakit. Sindrom geriatrimerupakan gabungan antara penurunan fisiologik dan berbagai proses patologik.[Medula Unila.2013;1(3):117-125