The SOS Platform: Designing, Tuning and Statistically Benchmarking Optimisation Algorithms

open access articleWe present Stochastic Optimisation Software (SOS), a Java platform facilitating the algorithmic design process and the evaluation of metaheuristic optimisation algorithms. SOS reduces the burden of coding miscellaneous methods for dealing with several bothersome and time-demanding tasks such as parameter tuning, implementation of comparison algorithms and testbed problems, collecting and processing data to display results, measuring algorithmic overhead, etc. SOS provides numerous off-the-shelf methods including: (1) customised implementations of statistical tests, such as the Wilcoxon rank-sum test and the Holm–Bonferroni procedure, for comparing the performances of optimisation algorithms and automatically generating result tables in PDF and formats; (2) the implementation of an original advanced statistical routine for accurately comparing couples of stochastic optimisation algorithms; (3) the implementation of a novel testbed suite for continuous optimisation, derived from the IEEE CEC 2014 benchmark, allowing for controlled activation of the rotation on each testbed function. Moreover, we briefly comment on the current state of the literature in stochastic optimisation and highlight similarities shared by modern metaheuristics inspired by nature. We argue that the vast majority of these algorithms are simply a reformulation of the same methods and that metaheuristics for optimisation should be simply treated as stochastic processes with less emphasis on the inspiring metaphor behind them

Velocity selection (without surface tension) in multi-connected Laplacian growth

We predict a novel selection phenomenon in nonlinear interface dynamics out of equilibrium. Using a recently developed formalism based on the Schottky-Klein prime functions, we extended the existing integrable theory from a single interface to multiple moving interfaces. After applying this extended theory to the two-dimensional Laplacian growth, we derive a new rich class of exact (non-singular) solutions for the unsteady dynamics of an arbitrary assembly of air bubbles within a layer of a viscous fluid in a Hele-Shaw cell. These solutions demonstrate that all bubbles reach an asymptotic velocity, $U$, which is {\it precisely twice} greater than the velocity, $V$, of the uniform background flow, i.e., $U=2V$. The result does not depend on the number of bubbles. It is worth to mention that contrary to common belief, the predicted velocity selection does not require surface tension.Comment: 5 pages, 1 figure. Updated versio

Kajian Aspek Interior Kantor (Studi Kasus : Pt. Balai Diklat Perkretaapian)

The office is a place used for business or can be referred to as the "Company" which is run regularly. Offices are divided into two types, namely large offices or so-called headquarters and simple offices or so-called branch offices. A pleasant office is a place that is not boring and can excite work. Balai Diklat Perkretaapian is the office where the work unit under the Badan Pengembangan Sumber Daya Manusia engaged in railway services. The problems and arrangements in this office vary from the lighting, the condition of the room, and the arrangement of furniture that affects the interior room. Physically, the interior of today's office is more needed in an open and intimate atmosphere. Proper application of color and light can eliminate existing dark corners. Massive walls can be reduced by placing transparent glass on some sides of the space so that the impression is wide and open. This problem is considered important to be solved and given a solution by making a study of the interior aspect of the office. The goal is to optimize the workspace in order to be able to restore the passion of the employees who work in it and give a first impression that is scarred to the client. Keywords: Aspects, Elements, Interior Design and OfficeKantor adalah tempat yang digunakan untuk perniagaan atau bisa disebut dengan “Perusahaan†yang dijalankan secara rutin. Kantor terbagi atas dua jenis, yaitu kantor besar atau yang sering disebut kantor pusat dan kantor sederhana atau disebut kantor cabang. Kantor yang  menyenangkan adalah tempat yang tidak membosankan dan dapat membangkitkan gairah kerja. Balai Diklat Perkeretaapian merupakan kantor tempat unit kerja di bawah Badan Pengembangan Sumber Daya Manusia yang bergerak dibidang layanan perkeretaapian. Permasalahan dan penataan pada kantor ini berbeda-beda dimulai dari tata cahaya, kondisi ruangan, serta penataan perabotan yang mempengaruhi ruangan interior tersebut. Secara fisik, interior kantor masa kini lebih dibutuhkan yang bersuasana terbuka dan akrab. Penerapan warna dan cahaya yang tepat dapat menghilangkan sudut-sudut gelap yang ada. Dinding masif dapat dikurangi dengan cara menempatkan kaca transparan di beberapa sisi ruang sehingga kesannya luas dan terbuka. Permasalahan ini dirasa penting untuk dipecahkan dan diberikan solusi dengan membuat sebuah kajian aspek interior kantor. Tujuannya dapat mengoptimalan ruang kerja agar mampu mengembalikan passion karyawan yang bekerja di  dalamnya dan memberikan kesan pertama yang membekas kepada klien. Kata Kunci : Aspek, Desain Interior, Elemen, dan Kanto

Doubly-periodic array of bubbles in a Hele-Shaw cell

Exact solutions are presented for a doubly-periodic array of steadily moving bubbles in a Hele-Shaw cell when surface tension is neglected. It is assumed that the bubbles either are symmetrical with respect to the channel centreline or have fore-and-aft symmetry, or both, so that the relevant flow domain can be reduced to a simply connected region. By using conformal mapping techniques, a general solution with any number of bubbles per unit cell is obtained in integral form. Several examples are given, including solutions for multi-file arrays of bubbles in the channel geometry and doubly-periodic solutions in an unbounded cell.Comment: 15 pages, 12 figure