An efficient, partitioned ensemble algorithm for simulating ensembles of evolutionary MHD flows at low magnetic Reynolds number

Studying the propagation of uncertainties in a nonlinear dynamical system usually involves generating a set of samples in the stochastic parameter space and then repeated simulations with different sampled parameters. The main difficulty faced in the process is the excessive computational cost. In this paper, we present an efficient, partitioned ensemble algorithm to determine multiple realizations of a reduced Magnetohydrodynamics (MHD) system, which models MHD flows at low magnetic Reynolds number. The algorithm decouples the fully coupled problem into two smaller sub-physics problems, which reduces the size of the linear systems that to be solved and allows the use of optimized codes for each sub-physics problem. Moreover, the resulting coefficient matrices are the same for all realizations at each time step, which allows faster computation of all realizations and significant savings in computational cost. We prove this algorithm is first order accurate and long time stable under a time step condition. Numerical examples are provided to verify the theoretical results and demonstrate the efficiency of the algorithm

Capital dependent population growth induces cycles

Cataloged from PDF version of article.Cobb–Douglas type production functions and time-delay are not sufficient for the economy to behave cyclic. However, capital dependent population dynamics can enforce Hopf bifurcation. 2011 Elsevier Ltd. All rights reserved

A sector analysis for RFID technologies: fundamental and technical analysis for financial decision making problems

Automatic identification technologies have been used in a wide range of applications for reducing the amount of time and labor needed to input data and improving data accuracy. As an important automatic identification technology, radio frequency identification (RFID) technologies allow contactless reading and these technologies are particularly successful in manufacturing and other environments where traditional identification technologies such as bar codes can not perform well. By integrating the RFID technology into their business models, companies may save time, lower labor cost, improve products quality and provide better service. RFID is the wireless technology that uses RF communication to identify, track and manage objects and collect and store data. RFID technology enables companies to develop applications that create value by tracking and identifying objects, animals or people. Business applications of RFID technology can be seen in areas such as manufacturing, supply chain management, software integration, security systems, asset tracking and many others. RFID technology was predicted to be one of the “top ten” technologies in 2004 by CNN. Although, the RFID market is less than five years old, it has been applied to many different industries, from retail industry to logistics, or from healthcare to service business industry – and it is still growing. Particularly, RFID has fundamental influences on today's retailing and supply chain management for applications like asset tracking the inventory control and management. RFID technology also finds major application in mobile phones and is widely used in toll collection of highways, for payments in restaurants, vending machines, retail and parking lots. There are a wide range of RFID systems currently being used or being developed. Examples to these systems include but not limited to the following; automatic vehicle and personnel access control for security (Simpson, 2006), airport passenger and baggage tracking (Ferguson, 2006), tracing blood for cutting down errors such as giving patients wrong blood types (Ranger, 2006), payment process systems (Ramachandran, 2006), production control in manufacturing (Liu & Miao, 2006), transfusion medicine (Knels, 2006) real-time inventory control by automated identification of items in warehouses, tracking and management of physical files, tracking of books in the libraries (Shadid, 2005). For some other applications, interested reader is referred to (Finkenzeller, 2003; Smith, 2004). RFID solution providers claim that their technology and solutions bring significant benefits and have valuable advantages in practice. As new RFID solutions being developed and more RFID tags and equipments being used, these solutions will become more cost effective and RFID businesses are expected to grow rapidly. Since RFID is fairly new, it’s difficult to measure resulting sales increases or heightened customer satisfaction quotients. On the other hand, according to IDC estimation (IDC is a subsidiary of International Data Group, a leading technology media, research, and events company and provider of market intelligence, advisory services, and events for the information technology, telecommunications, and consumer technology markets), companies in the retail sector will spend nearly $1.3 billion on RFID in their supply chain operations in 2008, compared to about$91.5 million in 2003 which corresponds to annual growth rate of 70 percent. In a similar look; the Wireless Data Research Group projected that the global market for RFID increased from $1 billion in 2003 to$3 billion in 2007 (Asif & Mandviwalla, 2005). There are two major drivers of this growth. The first one is the adoption of RFID technology by major retailers and government agencies. The second one is the reduction in the price of RFID tags, readers, and IT systems required to deploy RFID. Given the huge potential of RFID technology, there has been a huge emergence of RFID specialty companies and the development of RFID practices within many market-leading companies. Due to huge emergence, it is desirable to make a sector analysis. In this study, we perform a sector analysis for RFID technologies for researchers and analysts. We investigate public RFID companies traded on the stock exchange markets, summarize their financial performance, describe their RF products, services, and applications, and perform fundamental and technical analysis

Minimum Common Outage Probability for the Broadcast Relay Channel

In this paper the broadcast relay channel (BRC) is studied. In the BRC model, the source communicates with two destinations with the help of a single relay. The minimum common outage probability for four different transmission protocols, direct transmission (DT), multihop (MH), path selection (PS) and link combination with path selection (LCPS) is investigated under long-term power constraint for constant rate transmission. In addition, the epsilon-outage rate region for a fixed common outage probability is computed. Based on the cut-set bound (CSB), a lower bound on the minimum common outage probability and an upper bound on the epsilon-outage rate region are also found. Numerical results suggest that enforcing the relay to help both destinations simultaneously is limiting. The dominant factor in the gains obtained with respect to DT is due to path selection and link combination is not necessary when the relay is close to the source

Search for α\alpha decay of 151^{151}Eu to the first excited level of 147^{147}Pm using underground γ\gamma-ray spectrometry

The alpha decay of $^{151}$Eu to the first excited level of $^{147}$Pm ($J^\pi = 5/2^+$, $E_{exc}=91.1$ keV) was searched for at the HADES underground laboratory ($\approx 500$ m w.e.). A sample of high purity europium oxide with mass of 303 g and a natural isotopic composition has been measured over 2232.8 h with a high energy resolution ultra-low background n-type semi-planar HPGe detector (40 cm$^3$) with sub-micron deadlayer. The new improved half-life limit has been set as $T_{1/2} \geq 3.7\times 10^{18}$ yr at 68% C.L. Possibilities to improve the sensitivity of the experiment, which is already near the theoretical predictions, are discussed. New half-life limit for $\alpha$ decay of $^{153}$Eu is also set as $T_{1/2} \geq 5.5\times 10^{17}$ yr.Comment: 11 pages, 5 figures, 2 tables, 18 reference

A Survey About Nothing: Monitoring a Million Supergiants for Failed Supernovae

Extragalactic transient searches have historically been limited to looking for the appearance of new sources such as supernovae. It is now possible to carry out a new kind of survey that will do the opposite, that is, search for the disappearance of massive stars. This will entail the systematic observation of galaxies within a distance of 10 Mpc in order to watch ~10^6 supergiants. Reaching this critical number ensures that something will occur yearly, since these massive stars must end their lives with a core collapse within ~10^6 years. Using deep imaging and image subtraction it is possible to determine the fates of these stars whether they end with a bang (supernova) or a whimper (fall out of sight). Such a survey would place completely new limits on the total rate of all core collapses, which is critical for determining the validity of supernova models. It would also determine the properties of supernova progenitors, better characterize poorly understood optical transients, such as eta Carina-like mass ejections, find and characterize large numbers of Cepheids, luminous blue variables and eclipsing binaries, and allow the discovery of any new phenomena that inhabit this relatively unexplored parameter space.Comment: final version, 7 pages, 5 figures, ApJ in pres