There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

“Unpaired Image-to-Image Translation using Cycle-Consistent Adversarial Networks”の学習報告

The distributed nature and dynamic topology of Wireless Sensor Networks (WSNs) introduces very special requirements in routing protocols that should be met. The most important feature of a routing protocol, in order to be efficient for WSNs, is the energy consumption and the extension of the network's lifetime. During the recent years, many energy efficient routing protocols have been proposed for WSNs. In this paper, energy efficient routing protocols are classified into four main schemes: Network Structure, Communication Model, Topology Based and Reliable Routing. The routing protocols belonging to the first category can be further classified as flat or hierarchical. The routing protocols belonging to the second category can be further classified as Query-based or Coherent and non-coherent-based or Negotiation-based. The routing protocols belonging to the third category can be further classified as Location-based or Mobile Agent-based. The routing protocols belonging to the fourth category can be further classified as QoS-based or Multipath-based. Then, an analytical survey on energy efficient routing protocols for WSNs is provided. In this paper, the classification initially proposed by Al-Karaki, is expanded, in order to enhance all the proposed papers since 2004 and to better describe which issues/operations in each protocol illustrate/enhance the energy-efficiency issues.

Energy-Efficient Routing Protocols in Wireless Sensor Networks: A Survey

https://hal.archives-ouvertes.fr/hal-01009386/document

Energy efficiency in wireless sensor networks: A top-down survey

A new hypercube-type structure, the folded hypercube (FHC), which is basically a standard hypercube with some extra links established between its nodes, is proposed and analyzed. The hardware overhead is almost 1/n, n being the dimensionality of the hypercube, which is negligible for large n. For this new design, optimal routing algorithms are developed and proven to be remarkably more efficient than those of the conventional n-cube. For one-to-one communication, each node can reach any other node in the network in at most (n/2) hops (each hop corresponds to the traversal of a single link), as opposed to n hops in the standard hypercube. One-to-all communication (broadcasting) can also be performed in only (n/2) steps, yielding a 50% improvement in broadcasting time over that of the standard hypercube. All routing algorithms are simple and easy to implement. Correctness proofs for the algorithms are given. For the proposed architecture, communication parameters such as average distance, message traffic density, and communication time delay are derived. In addition, some fault tolerance capabilities of this architecture are quantified and compared to those of the standard cube. It is shown that this structure offers substantial improvement over existing hypercube-type networks in terms of the above-mentioned network parameters. >

Properties and performance of folded hypercubes

Wireless sensor networks (WSNs) are resource constraint: limited power supply, bandwidth for communication, processing speed, and memory space. One possible way of achieve maximum utilization of those resource is applying data compression on sensor data. Usually, processing data consumes much less power than transmitting data in wireless medium, so it is effective to apply data compression before transmitting data for reducing total power consumption by a sensor node. However, existing compression algorithms are not applicable for sensor nodes because of their limited resource. Therefore, some of compression algorithms, which have been specifically designed for WSNs, are presented in this paper: coding by ordering, pipelined in-network compression, low-complexity video compression, and distributed compression.

A survey on data compression in wireless sensor networks

Introduces a new measure of conditional connectivity for large regular graphs by requiring each vertex to have at least g good neighbors in the graph. Based on this requirement, the vertex connectivity for the n-dimensional cube is obtained, and the minimal sets of faulty nodes that disconnect the cube are characterized. >

Conditional connectivity measures for large multiprocessor systems

On the fault-diameter of the star graph

It is shown that the diameter of an n-dimensional hypercube can only increase by an additive constant of 1 when (n-1) faulty processors are present. Based on the concept of forbidden faulty sets, which guarantees the connectivity of the cube in the presence of up to (2n-3) faulty processors. It is shown that the diameter of the n-cube increases to (n-2) as a result of (2n-3) processor failures. It is also shown that only those nodes whose Hamming distance is (n-2) have the potential to be located at two ends of the diameter of the damaged cube. It is proven that all the n-cubes with (2n-3) faulty processors and a fault-diameter of (n+2) are isomorphic. A generalization to the subject study is presented. >

Shahram Latifi

Papers

Properties and performance of folded hypercubes

A survey on data compression in wireless sensor networks

Conditional connectivity measures for large multiprocessor systems

On the fault-diameter of the star graph

Combinatorial analysis of the fault-diameter of the n-cube