Coupled Lattice Boltzmann – discrete element method for numerical modelling of sand production

In this study, a coupled numerical approach based on Lattice Boltzmann Method (LBM) and Discrete Element Method (DEM) is employed for 2D simulation of fluid flow in porous media comprising of movable circular particles. The developed model is used for simulation of sand production which is one of the important problems in petroleum industry. The numerical tool has proved to have the capability of investigating the mechanisms involved in sand production problem. The results show that the rate of sand production is strongly affected by flow rate and confining pressure

Inference on P(Y<X) in Bivariate Rayleigh Distribution

This paper deals with the estimation of reliability $R=P(Y<X)$ when $X$ is a random strength of a component subjected to a random stress $Y$ and $(X,Y)$ follows a bivariate Rayleigh distribution. The maximum likelihood estimator of $R$ and its asymptotic distribution are obtained. An asymptotic confidence interval of $R$ is constructed using the asymptotic distribution. Also, two confidence intervals are proposed based on Bootstrap method and a computational approach. Testing of the reliability based on asymptotic distribution of $R$ is discussed. Simulation study to investigate performance of the confidence intervals and tests has been carried out. Also, a numerical example is given to illustrate the proposed approaches.Comment: Accepted for publication. Communications in Statistics- Theory and Methods, 201

Barriers Inhibiting the Development of a Self-Sustaining Virtual Learning Cluster of Schools in New Zealand: The Case of the C-Net Cluster

Secondary school students and teachers located in remote areas are faced with barriers to educational access not seen in denser population areas. Students cannot access teachers of specialised subjects and teachers in remote locations have limited professional learning and development opportunities. Virtual clustering of local, small, rural schools using video conferencing and collaborative networks is one of the approaches adopted by some schools to overcome the barriers. Although the use of ICT for forming a collaborative cluster seems a good strategy, self-sustainability of the clusters initiated and led by the community of schools from the grass-roots level remains a problem and has generated potential for a knowledge gap. This qualitative case study research intended to identify the inhibiting factors that challenged the development of C-Net as a self-sustaining Learning Exchange cluster in New Zealand. The process of Translation from Actor-Network Theory has been used to report the findings

Inference for the Rayleigh Distribution Based on Progressive Type-II Fuzzy Censored Data

Classical statistical analysis of the Rayleigh distribution deals with precise information. However, in real world situations, experimental performance results cannot always be recorded or measured precisely, but each observable event may only be identified with a fuzzy subset of the sample space. Therefore, the conventional procedures used for estimating the Rayleigh distribution parameter will need to be adapted to the new situation. This article discusses different estimation methods for the parameters of the Rayleigh distribution on the basis of a progressively type-II censoring scheme when the available observations are described by means of fuzzy information. They include the maximum likelihood estimation, highest posterior density estimation and method of moments. The estimation procedures are discussed in detail and compared via Monte Carlo simulations in terms of their average biases and mean squared errors. Finally, one real data set is analyzed for illustrative purposes

The clinical significance of biliary findings in magnetic resonance enterography of patients with inflammatory bowel disease

Purpose: Given the association of inflammatory bowel disease (IBD) and primary sclerosing cholangitis (PSC), we aimed to investigate the clinical relevance of abnormal hepatobiliary findings on magnetic resonance enterography (MRE) of IBD patients considering the risk of over- or underestimation of PSC at MRE. Material and methods: Using the MRE dataset of patients referring to a tertiary hospital and the National Registry of Crohn’s and Colitis, 69 MREs, including 23 IBD-PSC, 23 IBD-without PSC, and 23 healthy controls (HC), were retrospectively reviewed by 2 experienced radiologists blinded to the clinical data, to evaluate hepatobiliary abnormalities. Sensitivity, specificity, and likelihood ratios were calculated. Results: Bile duct irregularities were the most common finding in the IBD-PSC group, with a frequency of 91%. Intra- and extrahepatic bile duct (IHBD and EHBD) irregularities were observed in 87% and 78% of PSC patients, respectively. Higher frequency of IHBD and EHBD wall thickening, bile duct dilation, EHBD stricture, and periportal oedema were observed in the IBD-PSC group. Peribiliary T2-weighted hyperintensities and contrast-enhancement were significantly more common in the IBD-PSC group than in the IBD and HC groups (48% and 35%, respectively) (p < 0.001). Detection of biliary irregularities on MRE had a specificity of 94% (95% CI: 82-99%), a sensitivity of 91% (95% CI: 72-99%), and a positive likelihood ratio of 14.0 (95% CI: 4.7-42.1) for the diagnosis of PSC. Conclusions: This study emphasizes the importance of assessing and reporting hepatobiliary abnormalities visible in the MRE of patients with IBD to avoid a delayed diagnosis of PSC

Constraining four generation SM with b\to s \gamma and b\to s g decays

Using the experimental result on b\to s\gamma and theoretical result on b\to sg, a four -generation SM is analysed to constrain the rephasing-invariant combinations of the CKM matrix and masses of the fourth generation quarks.Comment: 10 pages, 4 figures via fax if requeste

Propulsion of a three-sphere micro-robot in a porous medium

Microorganisms and synthetic microswimmers often encounter complex environments consisting of networks of obstacles embedded into viscous fluids. Such settings include biological media, such as mucus with filamentous networks, as well as environmental scenarios, including wet soil and aquifers. A fundamental question in studying their locomotion is how the impermeability of these porous media impact their propulsion performance compared with the case that in a purely viscous fluid. Previous studies showed that the additional resistance due to the embedded obstacles leads to an enhanced propulsion of different types of swimmers, including undulatory swimmers, helical swimmers, and squirmers. In this work we employ a canonical three-sphere swimmer model to probe the impact of propulsion in porous media. The Brinkman equation is utilized to model a sparse network of stationary obstacles embedded into an incompressible Newtonian liquid. We present both a far-field theory and numerical simulations to characterize the propulsion performance of the swimmer in such porous media. In contrast to enhanced propulsion observed in other swimmer models, our results reveal that both the propulsion speed and efficiency of the three-sphere swimmer are largely reduced by the impermeability of the porous medium. We attribute the substantial reduction in propulsion performance to the screened hydrodynamic interactions among the spheres due to the more rapid spatial decays of flows in Brinkman media. These results highlight how enhanced or hindered propulsion in porous media is largely dependent on individual propulsion mechanisms. The specific example and physical insights provided here may guide the design of synthetic microswimmers for effective locomotion in porous media in their potential biological and environmental applications.Comment: 23 pages, 4 figure

Dipole coefficients in B -> X_s gamma in supersymmetry with large \tan\beta and explicit CP violation

We perform a detailed study of the electric and chromoelectric dipole coefficients in B -> X_s \gamma decay in a supersymmetric scheme with explicit CP violation. In our analysis, we adopt the minimal flavor violation scheme by taking into account the \tan\beta-enhanced large contributions beyond the leading order. We show that the coefficients can deviate from the SM prediction significantly in both real and imaginary directions. Experimental bounds still allow for large deviations from the SM predictions for both dipole coefficients such that the CP asymmetry is as large as \pm 8%. There are further implications of these coefficients for the charmless hadronic and semileptonic B decays. As a direct application of our analysis, we have discussed \Lambda_b -> \Lambda \gamma decay.Comment: 14 pp, 13 ps figs, a direct application of the computations is given, some figures and references are adde

Peer review_1 Artikel Taman Baca Desa Kec. Tulangan Kab. Sidoarjo

aman baca merupakan salah satu tempat pembelajaran yang efektif dalam meningkatkan tumbuh kembang anak, namun dengan meningkatnya perkembangan teknologi, taman baca bukanlah salah satu tempat favorit bagi sebagian masyarkat. Hal ini sangat kontra diktif karena pemerintah telah mencanangkan program gemar membaca. Guna memberikan penyadaaran kembali akan manfaat taman baca di kalangan anak usia dini, maka pendirian dan keberadaan Taman baca desa Kenongo di tujukan untuk memberikan stemulus bagi anak usia dini dalam upaya mengimplementasikan program gemar membaca. Hal ini sangat relevan mengingat keberadaan taman baca yang ada di lingkungan kantor desa kenongo tersebut satu komplek dengan sekolah PAUD dan TK. desain konsep Taman Baca yang di gagas mahasiswa KKN awalnya diperuntukkan oleh masyarkat umum, namun permasalahan yang di alami oleh taman baca adalah minimnya koleksi bacaan yang dimiliki menyebabkan kunjungan masyarakat ke taman baca sangat terbatas dan nyaris tidak ada, tempat display buku yang dibuat dari papan dengan kontruksi yang sederhana menyebabkan penataan buku tidak maksimal. Sehingga solusi yang ditawarkan adalah melakukan perubahan konsep taman baca yang tadinya diperuntukkan bagi masyarakat umum, akan di spesifikasikan sebagai taman baca anak usia dini, sehingga dengan perubahan konsep itu maka koleksi buku akan di tambah dengan memberikan porsi buku bacaan anak usia dini diperbanyak, yang kedua adalah membuat rak buku inovatif dengan konsep kontruksi yang lebih kuat dan tidak memakan tempat. Sehingga dengan perubahan konsep taman baca dan sentuhan teknologi rak buku inovatif tersebut maka Taman Baca desa Kenongo dapat dimaksimalkan potensinya menjadi taman baca yang dalam meningkatkan tumbuh kembang anak serta memberikan stemulus dalam upaya meningkatkan gemar membaca pada usia dini

Peer Review_1 Artikel PKM kelompok usaha lele Jawa Timur

Kebutuhan lele segar pada pelaku usaha makanan terutama di Jawa Timur diyakini memiliki potensi besar, sehingga banyaknya pelaku usaha pendukung seperti ternak lele berpeluang menjadi salah satu usaha andalan yang dapat dilakukan secara swadaya. Adalah bapak sukron (mitra 1) pelaku usaha ternak lele yang berada di desa kenongo kec. Tanggulangin, banyaknya tahapan yang dilakukan dalam berternak dari persiapan kolam, bibit, pakan menjadikan usaha ternak lele tersebut rentang atas masalah. Hal itu dapat terlihat dari banyaknya kolam yang dimiliki tetapi tidak ada satu papan nama yang menunjukkan atas kondisi dan status kolam dan lele yang ada, sehingga akan kesulitan jika menjelaskan waktu panen serta perlakuan lele atas pakan dan nutri yang harus diberikan. Sehingga solusi yang akan diberikan adalah adanya papan nama di setiap kolam yang berisikan identitas kolam serta kondisi lele dan pakan yang diberikan, sehingga memudahkan mitra dalam memonitoring keberadaan kolam dan kondisi lele tersebut. Sementara mitra 2 adalah pelaku usaha abon lele, yang berada di desa Mojorejo kec. Junrejo kota Batu Malang, yang kesehariannya adalah melakukan pengolahan lele segar yang di produksi menjadi abon lele, banyaknya pesanan yang dimiliki oleh mitra 2 memerlukan alat bantu proses pengeringan abon lele pasca pengolahan. Sehingga solusi yang ditawarkan adalah pembuatan alat pengering porteble yang inovatif yang nantinya berfungsi sebagai a lat alternatif pengering abon lele mitra 2. Dengan permasalahan dan solusi yang ada, maka, masing-masing mitra akan memperoleh manfaat yang lebih baik dan memberikan daya saing guna peningkatan pendapatan kelompok maupun anggota dan pelaku usaha