Complexity, parallel computation and statistical physics

The intuition that a long history is required for the emergence of complexity in natural systems is formalized using the notion of depth. The depth of a system is defined in terms of the number of parallel computational steps needed to simulate it. Depth provides an objective, irreducible measure of history applicable to systems of the kind studied in statistical physics. It is argued that physical complexity cannot occur in the absence of substantial depth and that depth is a useful proxy for physical complexity. The ideas are illustrated for a variety of systems in statistical physics.Comment: 21 pages, 7 figure

Distributed Collaborative Monitoring in Software Defined Networks

We propose a Distributed and Collaborative Monitoring system, DCM, with the following properties. First, DCM allow switches to collaboratively achieve flow monitoring tasks and balance measurement load. Second, DCM is able to perform per-flow monitoring, by which different groups of flows are monitored using different actions. Third, DCM is a memory-efficient solution for switch data plane and guarantees system scalability. DCM uses a novel two-stage Bloom filters to represent monitoring rules using small memory space. It utilizes the centralized SDN control to install, update, and reconstruct the two-stage Bloom filters in the switch data plane. We study how DCM performs two representative monitoring tasks, namely flow size counting and packet sampling, and evaluate its performance. Experiments using real data center and ISP traffic data on real network topologies show that DCM achieves highest measurement accuracy among existing solutions given the same memory budget of switches

An overview of recent research results and future research avenues using simulation studies in project management

This paper gives an overview of three simulation studies in dynamic project scheduling integrating baseline scheduling with risk analysis and project control. This integration is known in the literature as dynamic scheduling. An integrated project control method is presented using a project control simulation approach that combines the three topics into a single decision support system. The method makes use of Monte Carlo simulations and connects schedule risk analysis (SRA) with earned value management (EVM). A corrective action mechanism is added to the simulation model to measure the efficiency of two alternative project control methods. At the end of the paper, a summary of recent and state-of-the-art results is given, and directions for future research based on a new research study are presented

Tracer Applications of Noble Gas Radionuclides in the Geosciences

The noble gas radionuclides, including 81Kr (half-life = 229,000 yr), 85Kr (11 yr), and 39Ar (269 yr), possess nearly ideal chemical and physical properties for studies of earth and environmental processes. Recent advances in Atom Trap Trace Analysis (ATTA), a laser-based atom counting method, have enabled routine measurements of the radiokrypton isotopes, as well as the demonstration of the ability to measure 39Ar in environmental samples. Here we provide an overview of the ATTA technique, and a survey of recent progress made in several laboratories worldwide. We review the application of noble gas radionuclides in the geosciences and discuss how ATTA can help advance these fields, specifically determination of groundwater residence times using 81Kr, 85Kr, and 39Ar; dating old glacial ice using 81Kr; and an 39Ar survey of the main water masses of the oceans, to study circulation pathways and estimate mean residence times. Other scientific questions involving deeper circulation of fluids in the Earth's crust and mantle also are within the scope of future applications. We conclude that the geoscience community would greatly benefit from an ATTA facility dedicated to this field, with instrumentation for routine measurements, as well as for research on further development of ATTA methods

A Model for Collective Dynamics in Ant Raids

Ant raiding, the process of identifying and returning food to the nest or bivouac, is a fascinating example of collective motion in nature. During such raids ants lay pheromones to form trails for others to find a food source. In this work a coupled PDE/ODE model is introduced to study ant dynamics and pheromone concentration. The key idea is the introduction of two forms of ant dynamics: foraging and returning, each governed by different environmental and social cues. The model accounts for all aspects of the raiding cycle including local collisional interactions, the laying of pheromone along a trail, and the transition from one class of ants to another. Through analysis of an order parameter measuring the orientational order in the system, the model shows self-organization into a collective state consisting of lanes of ants moving in opposite directions as well as the transition back to the individual state once the food source is depleted matching prior experimental results. This indicates that in the absence of direct communication ants naturally form an efficient method for transporting food to the nest/bivouac. The model exhibits a continuous kinetic phase transition in the order parameter as a function of certain system parameters. The associated critical exponents are found, shedding light on the behavior of the system near the transition.Comment: Preprint Version, 30 pgs., 18 figures, complete version with supplementary movies to appear in Journal of Mathematical Biology (Springer

Transportation of concentration and leaching tailings in underground mining of metal deposits

Purpose. The article aims to substantiate efficient parameters of resource-saving technological processes ensuring optimal environmental and economic indices of concrete mixtures transportation under the force mode and changes of the transported mass parameters depending on transportation conditions. Methods. The complex method of investigation includes generalization and analysis of the theory and practice of mixtures transportation, theoretical and industrial research into the processes associated with long-haul delivery of mixtures, engineering forecasting, mathematical simulation with alternative calculation variants for the purpose of developing recommendations. Findings. Parameters of concentration and leaching tailings transportation under the force mode of a vibration wire were calculated in detail for the case of the haul length exceeding potential of the gravity flow. Calculation schemes for determining head losses and the flow critical velocity are created by alternative methods and ranked according to the reliability degree. Originality. Basic points of the new method for controlling indices of mixture preparation and transportation by changing the head and the feed rate of mixtures are defined for combined mineral mining. Practical implications. Solving the problem of hydromixture transportation under the force mode by joint application of accumulated industrial experience and simulation of delivery processes for combined mineral mining in order to achieve a complex environmental and economic effect.Мета. Обґрунтування раціональних параметрів ресурсозберігаючих технологічних процесів, що забезпечують оптимальні за еколого-економічними критеріями показники транспортування бетонних сумішей у режимі примусу і динаміки змінення параметрів переміщуваної маси у залежності від умов транспортування. Методика. Комплексний метод досліджень включає узагальнення й аналіз теорії та практики транспортування сумішей, теоретичні й виробничі дослідження процесів доставки сумішей на далеку відстань, інженерне прогнозування, математичне моделювання процесів із використанням альтернативних варіантів розрахунків для розробки рекомендацій. Результати. Деталізовано розрахунок параметрів транспортування хвостів збагачення і вилуговування у примусовому режимі роботи вібропроводу в умовах довжини доставки, що перевищує можливості самопливу. Дано розрахункові схеми визначення втрат напору та критичної швидкості потоку гідросуміші альтернативними методами з ранжируванням за ступенем надійності. Наукова новизна. Сформульована основа нового методу управління показниками приготування та транспортування сумішей при комбінованій розробці родовищ шляхом зміни напору і швидкості подачі сумішей. Практична значимість. Результати вирішення проблеми транспортування гідросумішей у режимі примусу шляхом спільного використання накопиченого виробничого досвіду та моделюванням процесів доставки для умов комбінованої розробки родовищ дозволяють одержати комплексний еколого-економічний ефект.Цель. Обоснование рациональных параметров ресурсосберегающих технологических процессов, обеспечивающих оптимальные по эколого-экономическим критериям показатели транспортирования бетонных смесей в режиме принуждения и динамики изменения параметров перемещаемой массы в зависимости от условий транспортирования. Методика. Комплексный метод исследований включает обобщение и анализ теории и практики транспортирования смесей, теоретические и производственные исследования процессов доставки смесей на дальнее расстояние, инженерное прогнозирование, математическое моделирование процессов с использованием альтернативных вариантов расчетов для разработки рекомендаций. Результаты. Детализирован расчет параметров транспортирования хвостов обогащения и выщелачивания в принудительном режиме работы вибропровода в условиях длины доставки, превышающей возможности самотека. Даны расчетные схемы определения потерь напора и критической скорости потока гидросмеси альтернативными методами с ранжированием по степени надежности. Научная новизна. Сформулирована основа нового метода управления показателями приготовления и транспортирования смесей при комбинированной разработке месторождений путем изменения напора и скорости подачи смесей. Практическая значимость. Результаты решения проблемы транспортирования гидросмесей в режиме принуждения путем совместного использования накопленного производственного опыта и моделированием процессов доставки для условий комбинированной разработки месторождений позволяют получить комплексный эколого-экономический эффект.The authors express their sincere gratitude to North Caucasian Mining and Metallurgical Institute and Kryvyi Rih National University for support in conducting research

Secure Routing in Wireless Mesh Networks

Wireless mesh networks (WMNs) have emerged as a promising concept to meet the challenges in next-generation networks such as providing flexible, adaptive, and reconfigurable architecture while offering cost-effective solutions to the service providers. Unlike traditional Wi-Fi networks, with each access point (AP) connected to the wired network, in WMNs only a subset of the APs are required to be connected to the wired network. The APs that are connected to the wired network are called the Internet gateways (IGWs), while the APs that do not have wired connections are called the mesh routers (MRs). The MRs are connected to the IGWs using multi-hop communication. The IGWs provide access to conventional clients and interconnect ad hoc, sensor, cellular, and other networks to the Internet. However, most of the existing routing protocols for WMNs are extensions of protocols originally designed for mobile ad hoc networks (MANETs) and thus they perform sub-optimally. Moreover, most routing protocols for WMNs are designed without security issues in mind, where the nodes are all assumed to be honest. In practical deployment scenarios, this assumption does not hold. This chapter provides a comprehensive overview of security issues in WMNs and then particularly focuses on secure routing in these networks. First, it identifies security vulnerabilities in the medium access control (MAC) and the network layers. Various possibilities of compromising data confidentiality, data integrity, replay attacks and offline cryptanalysis are also discussed. Then various types of attacks in the MAC and the network layers are discussed. After enumerating the various types of attacks on the MAC and the network layer, the chapter briefly discusses on some of the preventive mechanisms for these attacks.Comment: 44 pages, 17 figures, 5 table