Autonomous operation of multiple interconnected microgrids with self-healing capacity

This paper shows how multiple interconnected microgrids can operate in autonomous mode in a self–healing medium voltage network. This is possible if based on network self– healing capability, the neighbour microgrids are interconnected and a surplus generation capacity is available in some of the Distributed Energy Resources (DERs) of the interconnected microgrids. This will reduce or prevent load shedding within the microgrids with less generation capacity. Therefore, DERs in a microgrid are controlled such that they share the local load within that microgrid as well as the loads in other interconnected microgrids. Different control algorithms are proposed to manage the DERs at different operating conditions. On the other hand, a Distribution Static Compensator (DSTATCOM) is employed to regulate the voltage. The efficacy of the proposed power control, sharing and management among DERs in multiple interconnected microgrids is validated through extensive simulation studies using PSCAD/EMTDC.

Practical Advice to Entrepreneurs Series by ACE Adjunct Professor Dean Shepherd: Practical advice on transitioning from trauma to entrepreneurship

The author, Dean Shepherd, is of entrepreneurship—how entrepreneurs think, decide to act, and feel. He recently realized that while his publications in academic journals have implications for entrepreneurs, those implications have remained relatively hidden in the text of the articles and hidden in articles published in journals largely inaccessible to those involved in the entrepreneurial process. This series is designed to bring the practical implications of his research to the forefront.

Trauma overload

Reporting on death and accidents in regional and rural areas can exact a heavy toll on reporters. News reporters necessarily report on trauma. Overseas correspondents who report from war zones or areas of conflict or natural disaster are often exposed to physical risk and are sometimes required to confront extreme trauma. To an extent reporters embarking on overseas assignments are mentally prepared to face traumatic situations. Their supervisors are more or less aware of the reporter’s isolation and vulnerability...

One tune, three dances : using a traumatic stress framework to understand trauma survivors as networked news sources

Newman and Nelson (2012) describe three ‘dances’ to explain the vacillating psychological states of trauma survivors: the dance of approach and avoidance; the dance of fragmentation and integration; and the dance of resilience and vulnerability. The first pair of seemingly opposite responses describes how survivors at times cope by ‘approaching’ the trauma, for example by gathering information about what happened; whilst at other times, the same person will cope by ‘avoiding’ the trauma by engaging in activities which distract them from the memory of the trauma or having to deal with the consequences of it. The ‘dance’ of fragmentation and integration describes the opposing individual or group experiences encountered after traumas or disasters. Individuals may experience fragmentation, or emotional disconnection, from the trauma as an adaptive means of survival. The ‘dance’ of resilience and vulnerability refers to an individual’s ability to ‘process’ trauma and return to a resilient state in which they re-learn to trust people and the world around them and ‘bounce back’ to a state of being resilient again. This paper will illustrate how an understanding of the three dances can be used to enable survivors of child sexual assault to engage with the media to tell their stories. I will give current examples from six months of journalism research, collaboration and writing of a series of news stories and features which broke an exclusive story simultaneously in The Australian and The Times in London during 2013.

A coordinated voltage support strategy for LV network with multiple DSTATCOMs

Voltage rise and drop are the main power quality challenges in Low Voltage (LV) network with Renewable Energy (RE) generators. This paper proposes a new voltage support strategy based on coordination of multiple Distribution Static Synchronous Compensators (DSTATCOMs) using consensus algorithm. The study focuses on LV network with PV as the RE source for customers. The proposed approach applied to a typical residential LV network and its advantages are shown comparing with other voltage control strategies.

Primary control level of parallel distributed energy resources converters in system of multiple interconnected autonomous microgrids within self-healing networks

To minimise the number of load sheddings in a microgrid (MG) during autonomous operation, islanded neighbour MGs can be interconnected if they are on a self-healing network and an extra generation capacity is available in the distributed energy resources (DER) of one of the MGs. In this way, the total load in the system of interconnected MGs can be shared by all the DERs within those MGs. However, for this purpose, carefully designed self-healing and supply restoration control algorithm, protection systems and communication infrastructure are required at the network and MG levels. In this study, first, a hierarchical control structure is discussed for interconnecting the neighbour autonomous MGs where the introduced primary control level is the main focus of this study. Through the developed primary control level, this study demonstrates how the parallel DERs in the system of multiple interconnected autonomous MGs can properly share the load of the system. This controller is designed such that the converter-interfaced DERs operate in a voltage-controlled mode following a decentralised power sharing algorithm based on droop control. DER converters are controlled based on a per-phase technique instead of a conventional direct-quadratic transformation technique. In addition, linear quadratic regulator-based state feedback controllers, which are more stable than conventional proportional integrator controllers, are utilised to prevent instability and weak dynamic performances of the DERs when autonomous MGs are interconnected. The efficacy of the primary control level of the DERs in the system of multiple interconnected autonomous MGs is validated through the PSCAD/EMTDC simulations considering detailed dynamic models of DERs and converters.

Multiple-time signature schemes against adaptive chosen message attacks

Multiple-time signatures are digital signature schemes where the signer is able to sign a predetermined number of messages. They are interesting cryptographic primitives because they allow to solve many important cryptographic problems, and at the same time offer substantial efficiency advantage over ordinary digital signature schemes like RSA. Multiple-time signature schemes have found numerous applications, in ordinary, on-line/off-line, forward-secure signatures, and multicast/stream authentication. We propose a multiple-time signature scheme with very efficient signing and verifying. Our construction is based on a combination of one-way functions and cover-free families, and it is secure against the adaptive chosen-message attack.

Damage evaluation based on a wave energy flow map using multiple PZT sensors

A new wave energy flow (WEF) map concept was proposed in this work. Based on it, an improved technique incorporating the laser scanning method and Betti’s reciprocal theorem was developed to evaluate the shape and size of damage as well as to realize visualization of wave propagation. In this technique, a simple signal processing algorithm was proposed to construct the WEF map when waves propagate through an inspection region, and multiple lead zirconate titanate (PZT) sensors were employed to improve inspection reliability. Various damages in aluminum and carbon fiber reinforced plastic laminated plates were experimentally and numerically evaluated to validate this technique. The results show that it can effectively evaluate the shape and size of damage from wave field variations around the damage in the WEF map.

Verifiable multi-secret sharing schemes for multiple threshold access structures

A multi-secret sharing scheme allows several secrets to be shared amongst a group of participants. In 2005, Shao and Cao developed a verifiable multi-secret sharing scheme where each participant’s share can be used several times which reduces the number of interactions between the dealer and the group members. In addition some secrets may require a higher security level than others involving the need for different threshold values. Recently Chan and Chang designed such a scheme but their construction only allows a single secret to be shared per threshold value. In this article we combine the previous two approaches to design a multiple time verifiable multi-secret sharing scheme where several secrets can be shared for each threshold value. Since the running time is an important factor for practical applications, we will provide a complexity comparison of our combined approach with respect to the previous schemes.

Management of multiple heterogeneous UAVs using capability and autonomy visualisation: theory, experiment and result

The interest in utilising multiple heterogeneous Unmanned Aerial Vehicles (UAVs) in close proximity is growing rapidly. As such, many challenges are presented in the effective coordination and management of these UAVs; converting the current n-to-1 paradigm (n operators operating a single UAV) to the 1-to-n paradigm (one operator managing n UAVs). This paper introduces an Information Abstraction methodology used to produce the functional capability framework initially proposed by Chen et al. and its Level Of Detail (LOD) indexing scale. This framework was validated through comparing the operator workload and Situation Awareness (SA) of three experiment scenarios involving multiple autonomously heterogeneous UAVs. The first scenario was set in a high LOD configuration with highly abstracted UAV functional information; the second scenario was set in a mixed LOD configuration; and the final scenario was set in a low LOD configuration with maximal UAV functional information. Results show that there is a significant statistical decrease in operator workload when a UAV’s functional information is displayed at its physical form (low LOD - maximal information) when comparing to the mixed LOD configuration.

Multiple repeats of a promoter segment causes transcription factor autoregulation in red apples

Mutations in the genes encoding for either the biosynthetic or transcriptional regulation of the anthocyanin pathway have been linked to color phenotypes. Generally, this is a loss of function resulting in a reduction or a change in the distribution of anthocyanin. Here, we describe a rearrangement in the upstream regulatory region of the gene encoding an apple (Malus x domestica) anthocyanin-regulating transcription factor, MYB10. We show that this modification is responsible for increasing the level of anthocyanin throughout the plant to produce a striking phenotype that includes red foliage and red fruit flesh. This rearrangement is a series of multiple repeats, forming a minisatellite-like structure that comprises five direct tandem repeats of a 23-bp sequence. This MYB10 rearrangement is present in all the red foliage apple varieties and species tested but in none of the white fleshed varieties. Transient assays demonstrated that the 23-bp sequence motif is a target of the MYB10 protein itself, and the number of repeat units correlates with an increase in transactivation by MYB10 protein. We show that the repeat motif is capable of binding MYB10 protein in electrophoretic mobility shift assays. Taken together, these results indicate that an allelic rearrangement in the promoter of MYB10 has generated an autoregulatory locus, and this autoregulation is sufficient to account for the increase in MYB10 transcript levels and subsequent ectopic accumulation of anthocyanins throughout the plant.

Facilitating query decomposition in query language modeling by association rule mining using multiple sliding windows

This paper presents a novel framework to further advance the recent trend of using query decomposition and high-order term relationships in query language modeling, which takes into account terms implicitly associated with different subsets of query terms. Existing approaches, most remarkably the language model based on the Information Flow method are however unable to capture multiple levels of associations and also suffer from a high computational overhead. In this paper, we propose to compute association rules from pseudo feedback documents that are segmented into variable length chunks via multiple sliding windows of different sizes. Extensive experiments have been conducted on various TREC collections and our approach significantly outperforms a baseline Query Likelihood language model, the Relevance Model and the Information Flow model.

Associations between individual and workplace risk factors for self-reported neck pain and disability among female office workers

A cross-sectional survey of female office workers (n=333) was undertaken to determine the level of neck pain and disability (Neck Disability Index—NDI) and to explore the relationship between individual and workplace risk factors with the NDI score and the presence of pain. Workers reported nil (32%), mild (53%), moderate (14%) and severe (1%) neck pain. There were more risk factors associated with the NDI score than the presence of neck pain. The presence of neck pain was associated with a history of neck trauma (OR: 4.8), using a graduated lens (OR: 4.6), and negative affectivity (OR: 2.7) in the multiple regression model. Factors associated with higher NDI score were using the computer mouse for more than 6 h per day, higher negative affectivity, older age and an uncomfortable workstation. These results suggest that measuring the level of neck pain and disability rather than just the presence of neck pain provides more specific directives for the prevention and management of this disorder.