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

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

Perbaikan Teknologi Produksi Jamur Tiram Dengan Variasi Waktu Perendaman Media Tumbuh Serbuk Kayu Gergaji

Substrat serbuk kayu gergaji harus bebas polutan dan mempunyai kadar air 65-70% untuk mendukung pertumbuhan optimal miselium dan hasil maksimal jamur tiram. Penelitian bertujuan untuk mendapatkan lama perendaman bahan baku serbuk kayu gergaji (SKG) yang optimal untuk perbaikan produksi bobot jamur tiram. Percobaan menggunakan rancangan petak terpisah dengan tiga ulangan. Petak utama adalah spesies jamur tiram, yaitu Pleurotus sayor-caju, P. flabellatus, P. cystuidiosus, P. ostreatus strain florida, dan P. pulmonarius strain sylvan 301. Anak petak yaitu waktu perendaman substrat SKG, yaitu 0, 3, 6, 9, dan 12 jam. Penelitian dilakukan di Balai Penelitian Tanaman Sayuran, Lembang, Jawa Barat. Hasil penelitian menunjukkan bahwa P. ostreatus strain florida dan P. sayor-caju masing-masing menghasilkan bobot jamur segar tertinggi (970,27 dan 942,26 g/kg substrat basah). Efisiensi biologis tertinggi berasal dari P. cystidiosus (48,84%) dan P. sayor-caju (43,74%) yang dibudidayakan pada substrat SKG yang direndam selama 12 jam. Improving oyster mushrooms production technology by dipping time variation of sawdust medium. Sawdust as main raw material of substrate must be free from pollutant with its water content of 65-70%, to obtain high yield of oyster mushrooms. The goal of this experiment was to gain the optimum dipping time of sawdust as growing media to improve oyster mushrooms yield. A split plot design was arranged with three replications. Main plot was oyster mushrooms species of Pleurotus sayor-caju, P. flabellatus, P. cystuidiosus, P. ostreatus strain florida, and P. pulmonarius strain sylvan 301. Subplot was dipping time of sawdust of 0, 3, 6, 9, and 12 hours, respectively. Research activities was carried out at Indonesian Vegetable Research Institute Lembang, West Jawa. Research results revealed that P. ostreatus strain florida and P. sayor-caju independently produced the highest yield, viz: 970.27 and 942.26 g/kg wet substrate. The highest values of biological efficiency were found from P. cystuidiosus (48.84%) and P. sayor-caju (43.74%) cultivated on the substrate with 12 hours dipping time. Sawdust must be dipped at least for 6 hours prior to set up substrate formula in order to catch sufficient water content (65-70%) for better growth of mycelium and finally produce high yield of oyster mushrooms

EQCM Analysis of the Insertion Phenomena in a n-Doped Poly-Alkyl-Terthiophene With Regioregular Pattern of Substitution

In the present work, we have undertaken the study of the n-doping process in poly-3,3″-didodecyl-2,2′:5′,2″-terthiophene (poly-33″-DDTT) employing the electrochemical quartz crystal microbalance (EQCM). The present study aims at understanding how cathodic charge in n-doped poly-33″-DDTT is compensated. For this purpose, the in situ analysis of the variations of the polymeric mass has been considered. Poly-33″-DDTT was obtained as a thin coating onto a metallic substrate via the anodic coupling of the corresponding monomer 3,3″-didodecyl-2,2′:5′,2″-terthiophene (33″-DDTT). When subjected to electrochemical n-doping in the polarization interval -2.5 ≤ Eappl ≤ 0 V vs. Ag/Ag+, the films of poly-33″-DDTT varied their mass according to a mechanism of cations insertion during n-doping and cations extraction during polymer neutralization. In fact, the electrochemical doping of polythiophenes requires the accompanying exchange of charged species to maintain the electroneutrality within the structure of the polymer in all states of polarization. At the end of a full electrochemical cycle (consisting of the n-doping and the successive neutralization of poly-33″-DDTT), the polymer retains a fraction of the mass acquired during n-doping, thus manifesting the phenomena of mass trapping. The combined analysis of electrochemical and microgravimetric data suggests that poly-33″-DDTT in the n-doped state undergoes (or electrocatalyzes) uncontrolled electrochemical reactions that are not accompanied by mass variations

Identifikasi Mikoriza dari Lahan Desa Poteran, Pulau Poteran, Sumenep Madura

Mikoriza merupakan suatu bentuk simbiosis mutualisme antara cendawan dengan perakaran tanaman yang dapat membantu peningkatan penyerapan unsur-unsur hara tanah yang dibutuhkan oleh tanaman, berperan sebagai penghalang biologi terhadap infeksi patogen akar, dan memperpanjang fungsi perakaran. Penelitian ini bertujuan untuk mengetahui jenis MVA yang terdapat pada sampel tanah Desa Poteran. Identifikasi mikoriza dari lahan Desa Poteran dilakukan dengan menggunakan metode tuang saring basah kemudian diamati dengan mikroskop cahaya dan diidentifikasi hingga tingkat genus dengan menggunakan buku panduan Working with Mycorrhizas in FoPrestry and Agriculture serta dipertegas dengan menggunakan website INVAM. Karakteristik yang diamati adalah bentuk spora, warna spora dan ornamen spora. Hasil dari identifikasi mikoriza Desa Poteran ditemukan tiga genus spora yaitu genus Glomus, Acaulospora dan Gigaspora

Pengaruh Latar Belakang Pendidikan dan Pelatihan terhadap Kinerja Account Officer (Ao) Kredit Komersial Bank Bri Sumatera Barat

Penelitian ini bertujuan untuk mengungkapkan pengaruh: latar belakang pendidikan dan pelatihan terhadap kierja karyawan account officer (AO) Bank BRI Sumatera Barat. Jenis penelitian yang dilakukan dalam penelitian ini adalah Deskriptif Kuantitatif. Populasi dalam penelitian ini adalah jumlah keseluruhan karyawan account officer (AO) Bank BRI Sumatera berjumlah 30 orang. Teknik pengambilan sampel dalam penelitian ini adalah menggunakan total sampling dimana responden yang kurang dari 100 maka semua populasi dijadikan sampel. Data dikumpulkan melalui angket dengan menggunakan skala likert yang telah diuji kesahihan dan kehandalannya. Teknik analisis data yang digunakan adalah analisis deskriptif. Untuk pengujian hipotesis digunakan uji t dan uji f. Berdasarkan hasil pengujian hipotesis uji t latar belakang pendidikan tidak berpengaruh positif dan signifikan terhadap kinerja karyawan, uji t pelatihan berpengaruh positif dan signifikan terhadap kinerja karyawan. Sedangkan uji f pengaruh bersama-sama positif dan signifikan antara latar belakang pendidikan dan pelaihan terhadap kinerja karyawan. Besarnya pengaruh latar belakang pendidikan dan pelatihan terhadap kinerja karyawan adalah 32,90% dan sisanya sebesar 67,10% dipengaruhi oleh variabel lain yang tidak termasuk kedalam model penelitian

Biological systems interact with Engineered NanoMaterials (ENMs): Possible environmental risks

There is a growing and controversial public debate on the potential risk of NanoMaterials (NMs) to living organisms, including humans. In particular, the processes of dispersion and bioaccumulation of Engineered NanoMaterials (ENMs) into the environment are poorly investigated. Biological systems interact with ENMs in a very complex dynamic way whose comprehension is still at its infancy. Thus the evaluation of the environmental impact of ENMs may be useful to minimize or eliminate ENMs toxicity and/or ecotoxicity, and to help authorities to draw directives and regulations for a safe production and use of ENMs. Here we briefly review biotoxicity and environmental risks of ENMs (like carbon- and metalnanoparticles) reporting also our experience in the cytotoxicity of carbon (C) and silver (Ag) NanoParticles (NPs) on HeLa cells and nanoecotoxicity on Paracentrotus lividus