Liquid Level Sensor for High Temperature Molten Salt in Confined Container

Electrical resistance measurements on different rod materials in liquid solutions, molten salts, or molten lead are considered to design a liquid level sensor in a sealed containers when the temperature of the fluid is very high (~1000ºC) and conventional measurements are not possible due to properties of the fluid or condition of the container. An analytical solution to the problem is adopted to reduce the cost of the sensor and overcome the difficulties of calibration of sensors at high temperature for prediction of the level of liquid. An electrical circuit model is suggested for analytical solution to compute the resistivity versus height of the electrode rod submerged in the liquid in a narrow container. Good prediction of circuit model for experimental results is verified by comparison of analytical results of different combination of liquid solutions and rods’ material with experimental graphs

Returns to Education in Four Transition Countries: Quantile Regression Approach

This paper uses quantile regression techniques to analyze heterogeneous patterns of return to education across the conditional wage distribution in four transition countries. We correct for sample selection bias using a procedure suggested by Buchinsky (2001), which is based on a Newey (1991, 2009) power series expansion. We also examine the empirical implications of allowing for the endogeneity of schooling, using the control function approach proposed by Lee (2007). Using household data from Bulgaria, Russia, Kazakhstan and Serbia in 2003, we show that the return to education is heterogeneous across the earnings distribution. It is also found that accounting for the endogeneity of schooling leads to a higher rate of return to education.sample selection, endogeneity, rate of return to education, quantile regression

Irreversibility in response to forces acting on graphene sheets

The amount of rippling in graphene sheets is related to the interactions with the substrate or with the suspending structure. Here, we report on an irreversibility in the response to forces that act on suspended graphene sheets. This may explain why one always observes a ripple structure on suspended graphene. We show that a compression-relaxation mechanism produces static ripples on graphene sheets and determine a peculiar temperature $T_c$, such that for $T<T_c$ the free-energy of the rippled graphene is smaller than that of roughened graphene. We also show that $T_c$ depends on the structural parameters and increases with increasing sample size.Comment: 4 pages, 4 Figure

Mathematical Modeling, a Small Step in a Right Direction

Models developed by mathematicians/statisticians based on criterion such as goodness of fit often leads to a “best” model only for the data utilized. Moreover the parameters in such models often do not have physical interpretations and as such their validity cannot be checked by other means. This article makes argument against modeling processes that do not incorporate information from discipline related to the origin of data and presents an example to demonstrate benefits of doing so

Correcting the Eccentricity Error of Projected Spherical Objects in Perspective Cameras

Projective transformation of spheres onto images produce ellipses, whose centers do not coincide with the projected center of the sphere. This results in an eccentricity error, which must be treated in high precision metrology. This article provides closed formulations for modeling this error in images to enable 3-dimensional (3D) reconstruction of the center of spherical objects. The article also provides a new direct robust method for detecting spherical pattern in point clouds. It was shown that the eccentricity error in an image has only one component in the direction of the major axis of the ellipse. It was also revealed that the eccentricity is zero if and only if the center of the projected sphere lies on the camera’s perspective center. The effectiveness of the robust sphere detection and the eccentricity error modeling method was evaluated on simulated point clouds of spheres and real-world images, respectively. It was observed that the proposed robust sphere fitting method outperformed the popular M-estimator sample consensus in terms of radius and center estimation accuracy by a factor of 13, and 14 on average, respectively. Using the proposed eccentricity adjustment, the estimated 3D center of the sphere using modeled eccentricity was superior to the unmodeled case. It was also observed that the accuracy of the estimated 3D center using modeled eccentricity continuously improved as the number of images increased, whereas the unmodeled eccentricity did not show improvements after eight image views. The results of the investigation show that: (i) the proposed method effectively modeled the eccentricity error, and (ii) the effects of eliminating the eccentricity error in the 3D reconstruction become even more pronounced in a larger number of image views

Analisa Data Tekanan Untuk Menentukan Deskripsi Reservoir Dalam Melakukan Pengembangan Produksi Pada Formasi “X” Lapangan “Y”

Formasi “X” pada Lapangan “Y” merupakan sumur tua yang terletak 90 km dari sebelah barat Duriyang akan dilakukan optimisasi dan pengembangan lapangan. Alasan mengapa akan dilakukanpemgembangan produksi dikarenakan nilai RF yang masih mencapai 35% yang artinya masihdapat dioptimalkan. Untuk merencanakan optimisasi dan pengembangan di perlukan pertimbanganyang meliputi data core, PVT, data log, data produksi, dan hasil deskripsi reservoir pada Formasi“X” dengan melakukan analisa tekanan. Analisa tekanan yang digunakan yaitu analisa data ujiPressure Build Up dilakukan dengan bantuan software Ecrin, data Reapeated Formation Tester,dan data swab test. Dari ke tiga analisa diatas mendapatkan deskripsi reservoir bahwa terdapatPartial Communication pada Formasi “X” dan terdapat lebih dari satu kualitas reservoir, dari LowQuality – High Quality. Serta di pertkuat dari hasil pembacaan log terdapat lebih dari satu Lobespada tiap sumurnya. Untuk perencanaan pengembangan produksi akan dilakukan penambahansumur horizontal dikarenakan pada bagian Low Quality Reservoir masih belum dapatterproduksikan secara maksimal jika hanya melakukan pemboran secara vertikal saja. Sudahterdapat tiga sumur horizontal pada bagian atas formasi ini yaitu sumur AN040, AN041, AN042yang menghasilkan proven oil. Dari hasil analisa tekanan, analisa log, dan pembuatan Bubble mapdidapatkan kandidat letak sumur horizontal baru yang akan dilakukan pada Formasi “X” yangterletak pada bagian Selatan formasi ini

Penentuan Flow Unit Batuan Reservoir pada Lapangan Rn

Batuan karbonat merupakan salah satu batuan yang sangat bagus sebagai batuan reservoar, namun batuan ini memiliki tingkat heterogenitas yang sangat tinggi dibandingkan dengan batupasir sehingga memerlukan pendekatan dengan melakukan rock typing. Pada umumnya, indentifikasi rock type membutuhkan hasil pengukuran dari core dengan menggunakan beberapa metode yang telah ada. Namun, pada sumur-sumur yang tidak memiliki data core sangat sulit untuk menerapkan metode tersebut. Penelitian ini dilakukan dalam upaya untuk menentukan Hydraulic Flow Unit (HFU) reservoar pada sumur yang memiliki data core dengan menggunakan parameter Flow Zone Indicator (FZI) dan metode regresi non-parametrik yang disebut Alternating Conditional Expectation (ACE) pada sumur yang tidak memiliki data core. Dari hasil penelitian, reservoar pada lapangan RN dapat dikelompokkan menjadi delapan flow unit. Delapan flow unit tersebut masing-masing memiliki permeabilitas sebagai fungsi dari porositas yang telah divalidasi dengan mengaplikasikannya pada sumur. Dengan menggunakan metode ACE, kita dapat menentukan Hydraulic Flow Unit pada sumur yang tidak memiliki data core dengan menggunakan data log. Setelah FZI dihitung dari data log dan divalidasi dengan data core terlihat bahwa hasil dari metode tersebut menghasilkan korelasi yang cukup baik (R2 = 0.84), sehingga metode tersebut cukup dapat diaplikasikan pada sumur-sumur yang tidak memiliki data core

Deposition of general ellipsoidal particles

We present a systematic overview of granular deposits composed of ellipsoidal particles with different particle shapes and size polydispersities. We study the density and anisotropy of such deposits as functions of size polydispersity and two shape parameters that fully describe the shape of a general ellipsoid. Our results show that, while shape influences significantly the macroscopic properties of the deposits, polydispersity plays apparently a secondary role. The density attains a maximum for a particular family of non-symmetrical ellipsoids, larger than the density observed for prolate or oblate ellipsoids. As for anisotropy measures, the contact forces show are increasingly preferred along the vertical direction as the shape of the particles deviates for a sphere. The deposits are constructed by means of an efficient molecular dynamics method, where the contact forces are efficiently and accurately computed. The main results are discussed in the light of applications for porous media models and sedimentation processes.Comment: 7 pages, 8 figure