On Wireless Scheduling Using the Mean Power Assignment

In this paper the problem of scheduling with power control in wireless networks is studied: given a set of communication requests, one needs to assign the powers of the network nodes, and schedule the transmissions so that they can be done in a minimum time, taking into account the signal interference of concurrently transmitting nodes. The signal interference is modeled by SINR constraints. Approximation algorithms are given for this problem, which use the mean power assignment. The problem of schduling with fixed mean power assignment is also considered, and approximation guarantees are proven

Key Topics in Deep Geological Disposal : Conference Report (KIT Scientific Reports ; 7696)

The current state of knowledge of central aspects of radioactive waste repository research was presented in the course of the DAEF conference "Key topics in deep geological disposal". For the first time socio-economic and socio-technical issues played an important role within a conference focusing on the disposal of radioactive waste. Scientists from about 16 different countries presented their scientific work in 8 sessions and during a poster session

A Fast Exact Algorithm for the Optimum Cooperation Problem

Given a graph G=(V,E) with real edge weights, the optimum cooperation problem consists in determining a partition of the graph that maximizes the sum of weights of the edges having nodes in the same partition plus the number of resulting partitions. The problem is also known in the literature as the optimum attack problem in networks. It occurs as a subproblem in the separation of partition inequalities. Furthermore, a relevant physics application exists. Solution algorithms known in the literature require at least |V|-1 minimum cut computations in a corresponding network. In this work, we present a fast exact algorithm for the optimum cooperation problem. By graph-theoretic considerations and appropriately designed heuristics, we considerably reduce the number of minimum cut computations that are necessary in practice. We show the effectiveness of our method by comparing the performance of our algorithm with that of the fastest previously known method on instances coming from the physics application

A Fast Exact Algorithm for the Problem of Optimum Cooperation and Structure of Its Solutions

Given a graph with real edge weights, the optimum cooperation problem consists in determining a partition of the graph that maximizes the sum of weights of the edges with nodes in the same class plus the number of the classes of the partition. The problem is also known in the literature as the optimum attack problem in networks. Furthermore, a relevant physics application exists. In this work, we present a fast exact algorithm for the optimum cooperation problem. Algorithms known in the literature require n-1 minimum cut computations in a corresponding network, where n is the number of nodes in the graph. By theoretical considerations and appropriately designed heuristics, we considerably reduce the numbers of minimum cut computations that are necessary in practice. We show the effectiveness of our method by presenting results on instances coming from the physics application. Furthermore, we analyze the structure of the optimal solutions

A Fast Exact Algorithm for the Optimum Cooperation Problem

Given a graph G=(V,E) with real edge weights, the optimum cooperation problem consists in determining a partition of the graph that maximizes the sum of weights of the edges having nodes in the same partition plus the number of resulting partitions. The problem is also known in the literature as the optimum attack problem in networks. It occurs as a subproblem in the separation of partition inequalities. Furthermore, a relevant physics application exists. Solution algorithms known in the literature require at least |V|-1 minimum cut computations in a corresponding network. In this work, we present a fast exact algorithm for the optimum cooperation problem. By graph-theoretic considerations and appropriately designed heuristics, we considerably reduce the number of minimum cut computations that are necessary in practice. We show the effectiveness of our method by comparing the performance of our algorithm with that of the fastest previously known method on instances coming from the physics application

Сучасні тенденції в методиці викладання англійської мови

In the interference scheduling problem, one is given a set of n communication requests described by sourcedestination pairs of nodes from a metric space. The nodes correspond to devices in a wireless network. Each pair must be assigned a power level and a color such that the pairs in each color class can communicate simultaneously at the specified power levels. The feasibility of simultaneous communication within a color class is defined in terms of the Signal to Interference plus Noise Ratio (SINR) that compares the strength of a signal at a receiver to the sum of the strengths of other signals. The objective is to minimize the number of colors as this corresponds to the time needed to schedule all requests. We introduce an instance-based measure of interference, denoted by I, that enables us to improve on previous results for the interference scheduling problem. We prove upper and lower bounds in terms of I on the number of steps needed for scheduling a set of requests. For general power assignments, we prove a lower bound of Ω(I/(log ∆ log n)) steps, where ∆ denotes the aspect ratio of the metric. When restricting to the two-dimensional Euclidean space (as previous work) the bound improves to Ω(I / log ∆). Alternatively, when restricting to linear power assignments, the lower bound improves even to Ω(I). The lower bounds are complemented by an efficient algorithm computing a schedule for linear power assignments using onl

Annual Report 2015 / Institute for Nuclear Waste Disposal. (KIT Scientific Reports ; 7725)

The contributions collected in this report provide a representative overview of the scientific outcome of INE research activities in 2015. The structure of the report follows widely the organization of the institute according to research topics: basic research towards understanding geochemical reactions of radionuclides on a molecular scale and applied studies on radionuclide retention in multi-barrier system under real repository conditions