Integration of electric vehicles for load frequency output feedback H ∞ control of smart grids

This study considers a novel application of electric vehicles (EVs) to quickly help reheated thermal turbine units to provide the stability fluctuated by load demands. A mathematical model of a power system with EVs is first derived. This model contains the dynamic interactions of EVs and multiple network-induced time delays. Then, a dynamic output feedback H∞ controller for load frequency control of power systems with multiple time delays in the control input is proposed. To address the multiple time delays issue, a refined Jensen-based inequality, which encompasses the Jensen inequality, is used to derive less conservative synthesis conditions in terms of tractable linear matrix inequalities. A procedure is given to parameterise an output feedback controller to guarantee stability and H∞ performance of the closed-loop system. Extensive simulations are conducted to validate the proposed control method.

Identifying destination distances that support walking trips in local neighborhoods

When examining associations between local destinations and walking it is common to count local destinations using street network buffers measured at various distances to mitigate spatial data aggregation issues caused by scale and the Modifiable Areal Unit Problem. However, it remains unclear whether a particular buffer size is preferred since large buffers may mask important effects whilst small buffers may not accurately represent a neighborhood area. Furthermore, the use of various buffer distances in measuring destination counts does not yield specific information on distances where destinations could be placed in order to increase levels of walking. This paper extends current methods to address these issues by using a new method to define network buffers to identify threshold distances for walking to seven destination types using multilevel models. Donut-buffers are introduced as a method of counting destinations between distances of 401. m-800. m and 801. m-1200. m which are compared to standard network buffers at distances of 400. m, 800. m and 1200. m respectively. We found that destinations within 401. m-800. m could be responsible for associations found at a network buffer of 1200. m. Specifically, the odds of walking increased when local food outlets including supermarkets, cafés/takeaway stores, and small food stores, were located within 401. m-800. m but not 801. m-1200. m, suggesting that these destinations encourage walking when placed at 401. m-800. m away. Consequently we argue that donut-buffers offer greater specificity than standard network buffers for geographic measurement of destinations. This warrants further investigation to inform urban policy guidelines for designing walkable environments.

A digital signal processor controlled smart battery charger for photovoltaic power systems

An off-grid photovoltaic power system requires an energy storage system, especially batteries, for mitigation of variability and intermittency problems, and for assured service reliability and availability. The longevity and reliability of such batteries depend on the effectiveness of the charging system. This paper presents the modelling, simulation and hardware implementation of a four-stage switch-mode charger based on the single-ended primary inductance converter. The digital signal processor based controller implements algorithms for the system's power balance control, maximum power point tracking to improve charging speed and efficiency, four-stage optimal charging, and system's protection. The protection algorithm provides over-charge, overdischarge, over-temperature and short circuit protection capabilities. The proposed system has the following advantages: ability to continuously charge the batteries even at reduced solar irradiation, higher efficiency, and use of adaptive thermally compensated set points for optimum performance. A prototype is built and experimental results are presented to validate the simulation results.

Randomised controlled trial of a digitally assisted low intensity intervention to promote personal recovery in persisting psychosis: SMART-Therapy study protocol

BACKGROUND: Psychosocial interventions have an important role in promoting recovery in people with persisting psychotic disorders such as schizophrenia. Readily available, digital technology provides a means of developing therapeutic resources for use together by practitioners and mental health service users. As part of the Self-Management and Recovery Technology (SMART) research program, we have developed an online resource providing materials on illness self-management and personal recovery based on the Connectedness-Hope-Identity-Meaning-Empowerment (CHIME) framework. Content is communicated using videos featuring persons with lived experience of psychosis discussing how they have navigated issues in their own recovery. This was developed to be suitable for use on a tablet computer during sessions with a mental health worker to promote discussion about recovery.

METHODS/DESIGN: This is a rater-blinded randomised controlled trial comparing a low intensity recovery intervention of eight one-to-one face-to-face sessions with a mental health worker using the SMART website alongside routine care, versus an eight-session comparison condition, befriending. The recruitment target is 148 participants with a schizophrenia-related disorder or mood disorder with a history of psychosis, recruited from mental health services in Victoria, Australia. Following baseline assessment, participants are randomised to intervention, and complete follow up assessments at 3, 6 and 9 months post-baseline. The primary outcome is personal recovery measured using the Process of Recovery Questionnaire (QPR). Secondary outcomes include positive and negative symptoms assessed with the Positive and Negative Syndrome Scale, subjective experiences of psychosis, emotional symptoms, quality of life and resource use. Mechanisms of change via effects on self-stigma and self-efficacy will be examined.

DISCUSSION: This protocol describes a novel intervention which tests new therapeutic methods including in-session tablet computer use and video-based peer modelling. It also informs a possible low intensity intervention model potentially viable for delivery across the mental health workforce.