Describing the Flow Curve of Shear-Banding Fluids Through a Structural Minimal Model

Main characteristics of colloidal systems that develop fluid phases with different mechanical properties, namely shear-banding fluids, are briefly reviewed both from experimental and theoretical (modelling) point of view. A non-monotonic shear stress vs. shear rate constitutive relation is presented. This relation derives from a phenomenological model of a shear ratedependent viscosity describing structural changes and involves the possibility of multivalued shear rates under a given shear stress. In the case of a stress-dependent viscosity, the same model allows one to predict vorticity banding. Predictions of this model under controlled stress are discussed, namely occurrence of a kind of top- and bottom-jumping of the shear rate in response to stress increasing-decreasing. Applying this model to evaluation of the flow curve of such colloidal systems is performed. Particular emphasis is placed on the adequate computation of the shear rate function in cylindrical Couette cells in order to handle the corresponding flow curve which exhibits the well-known shear stress plateau. Indeed, as different fluid phases coexist in the flow domain, measured (torque vs. angular velocity) data cannot be directly converted into rheometric (shear stress vs. shear rate) functions. As the lacking non-local terms in the model prevents the direct determination of the stress-plateau, this value is included as an adjustable parameter. Thus model predictions satisfactorily match up experimental data of wormlike micellar solutions from the literature.Comment: 22 pages, 9 fi

On the Flow Curve of Colloids Presenting Shear-Induced Phase Transitions

This work deals with the evaluation of the flow curve of colloidal systems that develop fluid phases with different mechanical properties, namely shear-banding fluids. The problem involved is that, as different fluid phases coexist in the flow domain of the rheometric cell, measured data cannot be directly converted into rheometric functions. In order to handle this problem, a shear stress vs. shear rate constitutive relation is introduced to interpret the steady state flow curves. The relation derives from a phenomenological description of structural changes, and involves the possibility of multivalued shear rates under a given shear stress. Numerical predictions satisfactorily match up to experimental data of wormlike micellar solutions. A crucial aspect is the adequate computation of the shear rate function from raw data measured in the rheometric cell.Comment: 12 page

Multiple Studies: The Influence of Collaborative Learning Approach on Indonesian Secondary High School Students’ English-Speaking Skills

To respond the globalization, the importance of English communication skills including speaking skills increases. Looking at Indonesian context, secondary high school students find spoken English is much more difficult than written English. Students are good at grammar, reading, and writing but they can hardly speak (Hairdara, 2016). This article proposes collaborative learning approach (CLA) as one suitable solution to solve the obstacles of sharpening English speaking skills due to its benefits. The discussion of this investigation highlights some benefits of CLA in developing speaking skills and its challenges need to be considered as well. Receiving well-proven evidence of its benefits, CLA is recommended to be implemented in teaching and learning English speaking skills. As results of this investigation, there are three main benefits of CLA that its implementation can reduce language anxiety, raise students’ participation, and increase students’ self-confidence

On the Viscosity of Concentrated Suspensions of Charged Colloids

This work is concerned with the theoretical estimation of the low-shear viscosity of concentrated suspensions of charged-stabilized latex particles. Calculations are based on the assumption that particles interacting through purely repulsive potentials behave as equivalent hard-spheres (HS), and suspension viscosity may be analyzed in the framework of HS systems. In order to predict numerically the HS radius, the pair potential due to double-layer interaction, as a function of particle concentration, was investigated by using Poisson-Boltzmann theory and the cell model. Calculations explain appropriately experimental data for a wide range of particle sizes, volume fractions and salt concentrations. The problem concerning the effective surface charge of latex particles is also discussed.Fil: Berli, Claudio Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Deiber, Julio Alcides. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Quemada, Daniel. Universite Paris VII; Franci

Pengaruh Income Smoothing dan Corporate Governance Terhadap Return Saham Pada Perusahaan Perbankan tahun 2012-2017.

Penelitian ini bertujuan untuk menganalisa pengaruh income smoothing dan corporate governance terhadap return saham. Income smoothing diukur dengan model ekspektasi. Corporate governance diukur dengan corporate governance perception index dan return saham diukur dengan cummulative actual return. Penelitian ini dilakukan dengan sampel perusahaan perbankan yang terdaftar pada Bursa Efek Indonesia dan The Indonesian Institute for Corporate Governanceuntuk periode 2012-2017. Hasil penelitian ini menunjukkan bahwa income smoothing pengaruh positif terhadap return saham dan corporate governance berpengaruh negatif terhadap return saham. Hasil penelitian yang dilakukan dengan uji f (uji simultan) menunjukkan bahwa seluruh variabel bebas (income smoothing dan corporate governance), secara bersama-sama berpengaruh signifikan terhadap return saham. Kata Kunci: Income smoothing, corporate governance, stock return

Deteksi Cacat Bantalan Poros Engkol Motor Pembakaran dalam Menggunakan Spektrum Envelope

Bantalan poros engkol adalah salah satu komponen penting pada motor pembakaran-dalam (IC engine) yang dapat mengalami cacat akibat pembebanan berulang dan temperatur tinggi. Kerusakan bantalan menyebabkan penurunan kinerja mesin yang jika tidak segera dilakukan tindakan perawatan dapat mengakibatkan kerusakan total. Analisis spektrum getaran adalah teknik utama yang digunakan untuk mendeteksi cacat bantalan. Namun demikian, spektrum tidak efektif untuk mendeteksi cacat bantalan di mesin-mesin pembakaran-dalam karena menghasilkan background noise yang sangat besar sehingga menutup amplitudo getaran bantalan. Penelitian ini mengusulkan prosedur pre-processing sinyal getaran untuk mengeliminasi frekuensi-rendah-amplitudo-tinggi dan menguatkan amplitudo dari frekuensi bantalan. Penelitian ini menerapkan analisis envelope pada bantalan poros engkol motor pembakaran dalam 2 langkah. Eksperimen pada rig uji menggunakan 3 kondisi bantalan single row dari Danmotor yaitu bantalan normal (tidak cacat), cacat lintasan dalam ukuran 0,25 mm dan 0,50 mm. Kecepatan poros dijaga konstan pada variasi 1500 RPM dan 2000 RPM. Sensor akselerometer diletakkan pada blok mesin dekat dengan lokasi poros engkol untuk merekam sinyal getaran menggunakan kecepatan sampling 51200 Hz. Hasil penelitian menunjukan bahwa spektrum tidak dapat mendeteksi cacat bantalan untuk semua ukuran cacat dan kecepatan poros sedangkan spektrum envelope berhasil menampilkan BPFI dan side band yang dapat digunakan untuk mendeteksi cacat bantalan dan menentukan level cacatnya. A bearing on the crankshaft is one of critical component of the IC engine which may fault due to cyclic loading and high temperature. The vibration spectrum analysis is the main technique used to detect faulty bearings. However, it is not effective because IC engine produces a very large background noise which immerses bearing vibration amplitude. The study proposes a signal pre-processing procedure to eliminate low-frequency high-amplitude vibration and magnifies the amplitude of the bearing frequency. This paper applies envelope analysis on crankshaft bearings of two-strokes IC engine. The experiments on the test rig uses 3 condition of single row bearing from Danmotor i.e. normal bearing (healthy), inner race fault of 0,25 mm and 0,50 mm. The shaft speed of 1500 RPM and 2000 RPM is used during experiment. An accelerometer sensor is placed on the engine block near the location of the crankshaft to record vibration signals using 51200 Hz sampling rate. The result shows that spectrum fails to detect faulty bearing for all size defects and shaft speed. Meanwhile, envelope spectrum shows obvious BPFI and its side bands which can be used to detect and localize bearing fault. 

Advantages and limitations of molecular genetic prognostic tests for breast cancer. A systematic literature review

Background: Breast cancer is the most commonly diagnosed cancer in women internationally, and the most common cause of cancer related death among women. There are many ways to classify breast cancer, and breast cancer can be divided into several subgroups depending on which classification system is used. Pathological reports of breast carcinoma not only depend on one of these systems but include histopathological classification, grade of the tumor, and immunohistochemical (IHC) parameters like estrogen receptor (ER), progesterone receptor (PR), HER2- and Ki67-status. With the development of microarrays, it is now possible to analyze the genes of the cells, and with gene expression profiling (GEP) we have been able to evaluate breast cancer prognosis based on the gene expression of the cancer cells. Different genetic signatures of breast cancer have been obtained through DNA microarray technology, RNA sequencing and bioinformatic models. Some of these signatures have been validated through clinical studies and been translated into commercial prognostic assays. Four such commercial prognostic assays are Oncotype DX, MammaPrint, EndoPredict and PAM5-ROR. Methods: A literature search were conducted on the databases Medline and Embase. The inclusion criteria of the search were based on the Population, Intervention, Comparison and Outcome (PICO) framework. The search included terms to identify studies assessing the prognostic or economic aspects of Oncotype DX, MammaPrint, EndoPredict or Prosigna. Out of a total of 290 identified studies, 5 were included in this thesis. Results: Through the systematic literature search only studies focusing on Oncotype DX were included. The litterateur search disclosed that the Oncotype DX recurrence score (RS) is significantly associated with worse prognosis. The Oncotype DX RS were associated with both overall survival, disease free survival and local recurrence. The literature search also disclosed that Oncotype DX may be cost effective, especially in the high-risk RS group, were chemotherapy seemed to be clearly cost-effective because of the gain of additional quality- adjusted life-years (QUALY) at a low cost. Conclusion: The findings of this thesis suggest that Oncotype DX have an independent prognostic significance and is significantly associated with survival and risk of recurrence and may be helpful to guide treatment. Studies also show that Oncotype DX may be a cost effective alternative when used to guide adjuvant chemotherapy treatment

Deteksi Cacat Lintasan Luar Bantalan Bola pada Fan Industri Menggunakan Metode Cepstrum

Bantalan bola pada sebuah fan (kipas) menerima beban dinamis yang sangat besar ketika beroperasi. Hal ini menyebabkan bantalan mengalami keausan yang harus dapat segera dideteksi untuk mencegah kerusakan/cacat lebih lanjut. Salah satu metode deteksi yang sering digunakan adalah metode analisis spektrum. Namun metode ini menghasilkan harmonik dan sidebands yang rumit jika diaplikasikan pada fan dengan transmisi roda gigi sehingga observasi amplitudo pada spektrum sulit dilakukan. Penelitian ini mengusulkan metode cepstrum ketimbang spektrum karena cepstrum dapat mengelompokkan berbagai harmonik yang berasal dari getaran komponen-komponen fan sehingga amplitudo cacat bantalan dapat diidentifikasi dengan mudah dan jelas. Bantalan yang digunakan dalam penelitian adalah tipe ASB 6209 2RS dengan kondisi normal (tanpa cacat) dan cacat lintasan luar. Cacat pada bantalan sengaja dibuat menggunakan Electrical Discharge Machine (EDM)  dengan kawat kuningan berdiameter 0,25 mm. Hasil penelitian menunjukkan bahwa spektrum dapat mendeteksi frekuensi poros fan  9,11 Hz, frekuensi ball pass frequency outer (BPFO) 36,52 Hz, dan frekuensi poros roda gigi 22,59 Hz.  Namun demikian amplitudo BPFO sulit diidentifikasi pada spektrum karena secara visual bercampur dengan amplitudo harmonik dari komponen-komponen lain yang turut bergetar pada fan. Hasil lebih baik diberikan oleh metode cepstrum dimana amplitudo quefrency BPFO sebesar 0,027 detik, yang bersesuaian dengan BPFO, sangat jelas terlihat karena tidak terganggu oleh amplitudo lain di sekitarnya. A Ball bearing in a fan  experience a very large dynamic load during its operation. This causes wear which must be detected immediately to prevent severe damage. One detection method that is often used is the spectrum analysis. However, this method produces complex harmonics and sidebands when applied to a fan with a gear transmission which makes it difficult to observe amplitude on the spectrum. This research proposes the cepstrum method rather than the spectrum because the cepstrum can classify the various harmonics that come from the vibrations of the fan components so that the amplitude of the bearing defects can be identified easily and clearly. The bearings used in the study are ASB 6209 2RS with normal condition (no fault) and with outer race fault. Defect in the bearings is intentionally made using an Electrical Discharge Machine (EDM) with 0,25 mm brass wire. The results show that the spectrum can detect the fan shaft frequency of 9,11 Hz, the ball pass frequency outer race (BPFO) 36,52 Hz, and the gear shaft frequency of 22,59 Hz. However, the BPFO amplitude is difficult to identify on the spectrum because it is visually mixed with the harmonic amplitude of the other vibrating components. A prominent results are given by the cepstrum method where the quefrency of 0,027 s, which corresponds to the BPFO, is clearly visible because it is not disturbed by other amplitudes.

Lubrication model of a knee prosthesis, with non newtonian fluid and porous rough material

Tibial component of knee prostheses, made of ultra high molecular weight polyethylene (UHMWPE), experiences a high degree of wear and may be expected to last twelve years on average. In this work, a steady state one-dimensional lubrication model of a knee prosthesis is solved through a nu-merical technique based on the Finite Element Method. The model takes into account a non Newto-nian synovial fluid, its ultra filtration mechanism and the surface roughness of a porous elastic layer on the tibial component. The benefits of a porous compliant material placed at the top of the metallic tibial component are shown taking into account the stiffness and exudation capacity of the material and hyaluronic acid concentration of synovial fluid.Fil: Berli, Marcelo Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina. Universidad Nacional de Entre Ríos. Facultad de Ingeniería; ArgentinaFil: Campana, Diego Martin. Universidad Nacional de Entre Ríos. Facultad de Ingeniería; ArgentinaFil: Ubal, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Di Paolo, José. Universidad Nacional de Entre Ríos. Facultad de Ingeniería; Argentin