Abstract Geomagnetic disturbances have affected electrical systems on the ground for over 150 years. The first effects were noted on the early telegraph in the 1840s and in this century magnetic storms have caused power system blackouts and phone system outages. Affected systems include all those that use electrical conductors: whether for transmission of power or signals or where the conducting properties are incidental to their use such as with pipelines and railway tracks. In power systems geomagnetically induced currents cause partial saturation of power transformers producing transformer heating and distortion of the ac waveform leading to misoperation of relays and other equipment. On pipelines, induced currents may contribute to corrosion but also present a problem with the electrical surveys of the pipe performed to monitor the corrosion prevention systems. Severity of these effects depends on disturbance size, proximity to the auroral zone, and the conductivity structure of the Earth. Also significant are system parameters such as the use of higher resistance coatings on pipelines and the linking of power systems into larger networks. In this paper we have attempted to catalogue all the published reports of geomagnetic effects on electrical systems and show their occurrence in the context of the solar cycle and geomagnetic activity variations for the years 1844 to 1996.

The Effects of Geomagnetic Disturbances on Electrical Systems at the Earth's Surface - An Update

The performance of the Mel-Frequency Cepstrum Coefficients (MFCC) may be affected by (1) the number of filters, (2) the shape of filters, (3) the way in which filters are spaced, and (4) the way in which the power spectrum is warped. In this paper, several comparison experiments are done to find a best implementation. The traditional MFCC calculation excludes the 0th coefficient for the reason that it is regarded as somewhat unreliable. According to the analysis and experiments, the authors find that it can be regarded as the generalized frequency band energy (FBE) and is hence useful, which results in the FBE-MFCC. The authors also propose a better analysis, namely the auto-regressive analysis, on the frame energy,which outperforms its 1st and/or 2nd order differential derivatives. Experiments with the “863”Speech Database show that, compared with the traditional MFCC with its corresponding autoregressive analysis coefficients, the FBE-MFCC and the frame energy with their corresponding auto-regressive analysis coefficients form the best combination, reducing the Chinese syllable error rate (CSER) by about 10%, while the FBE-MFCC with the corresponding auto-regressive analysis coefficients reduces CSER by 2.5%. Comparison experiments are also done with a quite casual Chinese speech database, named Chinese Annotated Spontaneous Speech (CASS)corpus. The FBE-MFCC can reduce the error rate by about 2.9% on an average.

Comparison of Different Implementations of MFCC

The Internet of Things (IoT) is leading today’s digital transformation Relying on a combination of technologies, protocols, and devices such as wireless sensors and newly developed wearable and implanted sensors, IoT is changing every aspect of daily life, especially recent applications in digital healthcare IoT incorporates various kinds of hardware, communication protocols, and services This IoT diversity can be viewed as a double-edged sword that provides comfort to users but can lead also to a large number of security threats and attacks In this survey paper, a new compacted and optimized architecture for IoT is proposed based on five layers Likewise, we propose a new classification of security threats and attacks based on new IoT architecture The IoT architecture involves a physical perception layer, a network and protocol layer, a transport layer, an application layer, and a data and cloud services layer First, the physical sensing layer incorporates the basic hardware used by IoT Second, we highlight the various network and protocol technologies employed by IoT, and review the security threats and solutions Transport protocols are exhibited and the security threats against them are discussed while providing common solutions Then, the application layer involves application protocols and lightweight encryption algorithms for IoT Finally, in the data and cloud services layer, the main important security features of IoT cloud platforms are addressed, involving confidentiality, integrity, authorization, authentication, and encryption protocols The paper is concluded by presenting the open research issues and future directions towards securing IoT, including the lack of standardized lightweight encryption algorithms, the use of machine-learning algorithms to enhance security and the related challenges, the use of Blockchain to address security challenges in IoT, and the implications of IoT deployment in 5G and beyond

https://www.mdpi.com/1424-8220/20/13/3625/pdf

A Survey of IoT Security Based on a Layered Architecture of Sensing and Data Analysis.

Wireless sensor networks (WSN) over the years have become one of the most promising networking solutions with exciting new applications for the near future. Its deployment has been enhanced by its small, inexpensive, and smart sensor nodes, which are easily deployed, depending on its application and coverage area. Common applications include its use for military operations, monitoring environmental conditions (such as volcano detection, agriculture, and management), distributed control systems, healthcare, and the detection of radioactive sources. Notwithstanding its promising attributes, security in WSN is a big challenge and remains an ongoing research trend. Deployed sensor nodes are vulnerable to various security attacks due to its architecture, hostile deployment location, and insecure routing protocol. Furthermore, the sensor nodes in WSNs are characterized by their resource constraints, such as, limited energy, low bandwidth, short communication range, limited processing, and storage capacity, which have made the sensor nodes an easy target. Therefore, in this paper, we present a review of denial of service attacks that affect resource availability in WSN and their countermeasure by presenting a taxonomy. Future research directions and open research issues are also discussed.

Denial of Service Defence for Resource Availability in Wireless Sensor Networks

Cosmic Electrodynamics By J. H. Piddington. (Interscience Monographs and Texts in Physics and Astronomy, Vol. 23.) Pp. x + 305. (Wiley (Interscience): New York and London, March 1970.) 175s.

/pdf/the-magnetic-universe-471c4irviq.pdf

The Magnetic Universe

Wireless sensor networks (WSNs) form an important part of industrial application. There has been growing interest in the potential use of WSNs in applications such as environment monitoring, disaster management, health care monitoring, intelligence surveillance and defence reconnaissance. In these applications, the sensor nodes (SNs) are envisaged to be deployed in sizeable numbers in an outlying area, and it is quite difficult to replace these SNs after complete deployment in many scenarios. Therefore, as SNs are predominantly battery powered devices, the energy consumption of the nodes must be properly managed in order to prolong the network lifetime and functionality to a rational time. Different energy-efficient and energy-balanced routing protocols have been proposed in literature over the years. The energy-efficient routing protocols strive to increase the network lifetime by minimizing the energy consumption in each SN. On the other hand, the energy-balanced routing protocols protract the network lifetime by uniformly balancing the energy consumption among the nodes in the network. There have been various survey papers put forward by researchers to review the performance and classify the different energy-efficient routing protocols for WSNs. However, there seems to be no clear survey emphasizing the importance, concepts, and principles of load-balanced energy routing protocols for WSNs. In this paper, we provide a clear picture of both the energy-efficient and energy-balanced routing protocols for WSNs. More importantly, this paper presents an extensive survey of the different state-of-the-art energy-efficient and energy-balanced routing protocols. A taxonomy is introduced in this paper to classify the surveyed energy-efficient and energy-balanced routing protocols based on their proposed mode of communication towards the base station (BS). In addition, we classified these routing protocols based on the solution types or algorithms, and the input decision variables defined in the routing algorithm. The strengths and weaknesses of the choice of the decision variables used in the design of these energy-efficient and energy-balanced routing protocols are emphasised. Finally, we suggest possible research directions in order to optimize the energy consumption in sensor networks.

A Survey on an Energy-Efficient and Energy-Balanced Routing Protocol for Wireless Sensor Networks.

Prolonging the network lifetime for a reasonable period while meeting users' needs is key in developing a data gathering algorithm for WSNs. Clustered sensor networks are considered as an efficient approach for extending the network lifetime of WSNs. In clustering, sensor devices are arranged in clusters. Inside the cluster, non-cluster head nodes transmit data to the cluster head (
 C
 H
) nodes while the C
 H
 forward the message to the sink. Irrespective of how the clusters are formed, a clustered WSN requires sturdy energy-balanced (EB) and energy-efficient (EE) communication protocol. Different from the previous clustered based routing protocol, this paper develops and analyses a selective-path priority table EB and EE clustering based routing protocol, which employs a mobile sink. The priority table is formed by prioritising the two shortest paths to the C
 H
 or sink according to some simple but efficient rules. The rules are derived using some routing metrics such as transmission range/power and residual energy. The simulation results show that the proposed routing protocol can be integrated with most clustering formation algorithms, even in large scale WSNs. Besides, results show that this routing protocol improve the network lifetime and throughput as compared to similar schemes.

https://ietresearch.onlinelibrary.wiley.com/doi/epdf/10.1049/iet-com.2018.6163

Energy-balanced and energy-efficient clustering routing protocol for wireless sensor networks

Cetaceans have elicited the attention of researchers in recent decades due to their importance to the ecosystem and their economic values. They use sound for communication, echolocation and other social activities. Their sounds are highly non-stationary, transitory and range from short to long sounds. Passive acoustic monitoring (PAM) is a popular method used for monitoring cetaceans in their ecosystems. The volumes of data accumulated using PAM are usually big, so they are difficult to analyze using manual inspection. Therefore different techniques with mixed outcomes have been developed for the automatic detection and classification of signals of different cetacean species. So far, no single technique developed is perfect to detect and classify the vocalizations of over 82 known species due to variability in time-frequency, difference in the amplitude among species and within species' vocal repertoire, physical environment, among others. The accuracy of any detector or classifier depends on the technique adopted as well as the nature of the signal to be analyzed. In this article, we review the existing techniques for the automatic detection and classification of cetacean vocalizations. We categorize the surveyed techniques, while emphasizing the advantages and disadvantages of these techniques. The article suggests possible research directions that can improve existing detection and classification techniques. In addition, the article recommends other suitable techniques that can be used to analyze non-linear and non-stationary signals such as the cetaceans' signals. Several research have been dedicated to this topic, however, there is no review of these past results that gives a quick overview in the area of cetacean detection and classification. This review will help researchers and practitioners in the field to make insightful decisions based on their requirements.

/pdf/review-of-automatic-detection-and-classification-techniques-3o7cugfdlz.pdf

Review of Automatic Detection and Classification Techniques for Cetacean Vocalization

A symbol level iterative soft decision (SD) algorithm for Reed-Solomon codes based on parity-check equations is developed. This is achieved by transforming the systematic parity-check matrix according to some rules. The rules are based on the soft reliability information matrix derived from the received vector. The symbol error rate performance of the resulting algorithm is documented through computer simulation and compared with the hard decision Berlekamp-Massey (B-M) algorithm, and the Koetter and Vardy-Guruswami and Sudan (KV-GS) algorithm. The result verifies that the iterative (SD) algorithm outperforms the KV-GS and B-M algorithms by a significant margin while maintaining a reasonable decoding time complexity level.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/el.2015.1932

Symbol level iterative soft decision decoder for Reed-Solomon codes based on parity-check equations

The advancement in wireless communication applications encourages the use of effective and efficient channel estimation (CE) techniques because of the varying behaviour of the Rayleigh fading channel. In most cases, the emphasis of most proposed CE schemes is to improve the CE performance and complexity for ensuring quality signal reception and improved system throughput. Candidate waveforms whose designs are based on filter bank multi-carrier (FBMC) modulation techniques such as filter bank orthogonal frequency division multiplexing based on offset quadrature amplitude modulation (OFDM-OQAM), universal filtered multicarrier (UFMC) and generalised frequency division multiplexing based on offset quadrature amplitude modulation (GFDM-OQAM) are no exception to the use of these proposed CE techniques in the literature. These schemes are considered as potential waveform candidates for the physical/media access control layer of the emerging fifth generation (5G) networks. Therefore, pinpoint CE techniques represent an important requirement for these waveforms to attain their full potentials. In this regard, this paper reviews the concept of CE as applicable to these waveforms as well as other waveform candidates under consideration in the emerging 5G networks. Since the design of the majority of the waveform candidates is filter based, a review of the general filter design considerations is presented in this paper. Secondly, we review general CE techniques for candidate waveforms of next generation networks and classify some of the studied CE techniques. In particular, we classify the CE schemes used in filter bank OFDM-OQAM and GFDM-OQAM based transceivers and present a performance comparison of some of these CE schemes. Besides, the paper reviews the performances of two linear CE schemes and three adaptive based CE schemes for two FBMC based waveform candidates assuming near perfect reconstruction (NPR) and non-perfect reconstruction (Non-PR) filter designs over slow and fast frequency selective Rayleigh fading channels. The results obtained are documented through computer simulations, where the performances of the studied CE schemes in terms of the normalised mean square error (NMSE) are analysed. Lastly, we summarise the findings of this work and suggest possible research directions in order to improve the potentials of the studied candidate waveforms over Rayleigh fading channels.

https://www.mdpi.com/2079-9292/8/9/956/pdf

Olayinka O. Ogundile

Papers

A Survey on an Energy-Efficient and Energy-Balanced Routing Protocol for Wireless Sensor Networks.

Energy-balanced and energy-efficient clustering routing protocol for wireless sensor networks

Review of Automatic Detection and Classification Techniques for Cetacean Vocalization

Symbol level iterative soft decision decoder for Reed-Solomon codes based on parity-check equations

Review of channel estimation for candidate waveforms of next generation networks