A phase-locked-loop design for the smooth operation of a hybrid microgrid

A microgrid contains both distributed generators (DGs) and loads and can be viewed by a controllable load by utilities. The DGs can be either inertial synchronous generators or non-inertial converter interfaced. Moreover, some of them can come online or go offline in plug and play fashion. The combination of these various types of operation makes the microgrid control a challenging task, especially when the microgrid operates in an autonomous mode. In this paper, a new phase locked loop (PLL) algorithm is proposed for smooth synchronization of plug and play DGs. A frequency droop for power sharing is used and a pseudo inertia has been introduced to non-inertial DGs in order to match their response with inertial DGs. The proposed strategy is validated through PSCAD simulation studies.

The influence of Monte Carlo source parameters on detector design and dose perturbation in small field dosimetry

To obtain accurate Monte Carlo simulations of small radiation fields, it is important model the initial source parameters (electron energy and spot size) accurately. However recent studies have shown that small field dosimetry correction factors are insensitive to these parameters. The aim of this work is to extend this concept to test if these parameters affect dose perturbations in general, which is important for detector design and calculating perturbation correction factors. The EGSnrc C++ user code cavity was used for all simulations. Varying amounts of air between 0 and 2 mm were deliberately introduced upstream to a diode and the dose perturbation caused by the air was quantified. These simulations were then repeated using a range of initial electron energies (5.5 to 7.0 MeV) and electron spot sizes (0.7 to 2.2 FWHM). The resultant dose perturbations were large. For example 2 mm of air caused a dose reduction of up to 31% when simulated with a 6 mm field size. However these values did not vary by more than 2 % when simulated across the full range of source parameters tested. If a detector is modified by the introduction of air, one can be confident that the response of the detector will be the same across all similar linear accelerators and the Monte Carlo modelling of each machine is not required.

Trade marks for the design and layout of retail premises

In January 2013, Apple Inc obtained United States trademarks for the design and layout of its retail stores. While innovative brand protection strategies of this kind are not without precedent in the United States, traders in Australia have seemingly not adopted them. This article considers the prospects of an applicant seeking to register a similar trade mark in Australia and the protection such a registration would likely provide.

Making the case for improved structural design : tornado outbreaks of 2011

A total of 1,625 tornadoes occurred in the United States in 2011, resulting in economic losses that exceeded $25 billion. Two tornado outbreaks stand out because they caused more than half of those losses. The tornadoes that cut through Tuscaloosa, Alabama, on April 27 and Joplin, Missouri, on May 22 were responsible for a combined 223 fatalities and more than 13,000 damaged buildings in the two cities. Although the economic losses associated with tornado damage are well documented, the writers argue that the overall impact should encompass longer term, broader considerations such as the social disruption and psychological effects that impact communities. This paper examines observations by tornado damage assessment teams led by the first author in these two medium-sized cities and suggests that the evolution of building codes and past approaches to construction have led to conditions that made this extent of damage possible. The authors outline a multidisciplinary path forward that incorporates engineering research and social and economic studies into a new design paradigm leading to building code changes and social practices that will improve resistance and mitigate future losses at a community level from tornadoes.

Stimulating organizational ingenuity with design methods

Organizations invest in ways to stimulate new ideas for new products and services for the benefit of the organization, engaging in tournaments and competitions to generate new ideas or to combine existing ideas in new ways for new products and services (Terweisch and Uhlrich, 2009). Specifically, some large companies have developed platforms for posting intractable problems to tap into the ideas and problem solving abilities of a broader range of people (Huston and Sakkab, 2006; Morgan and Wang, 2010), and to develop new and elegant solutions often in an open innovation approach (Chesbrough, 2003). The notion of ingenuity is often applied to individuals who create innovative solutions in situations of constraint, where ingenuity in the form of elegant solutions can be understood as one form of resourcefulness (Young, 2011). However, the notion of organizational ingenuity locates ingenuity more centrally to an organization's strategic decision making and implementation, embedding ingenuity into the company's culture. Studies of organizations displaying ingenuity indicate a range of possibilities from extreme ingenuity (Baker and Nelson, 2005) to less dramatic but substantial changes (Thomke, 2003), sometimes in an experimental phase or as part of a move towards a new and distinct identity for ongoing innovation.

Engineering Design

Engineering Your Future: An Australasian Guide, 2nd Edition, is the ideal textbook for undergraduate students beginning their engineering studies. Building on the success of the popular 1st edition, this new edition continues the strong and practical emphasis on skills that are essential for engineering problem-solving and design. Numerous topical and locally focused examples of projects across the broad range of engineering disciplines help to graphically demonstrate the role and responsibilities of a professional engineer. Themes of sustainability, ethical practice and effective communication are constant throughout the text. In addition, its many exercises and project activities will encourage students to put key engineering principles and skills into practice.

Non-formal techniques for early assessment of design ideas for services

Designing systems for multiple stakeholders requires frequent collaboration with multiple stakeholders from the start. In many cases at least some stakeholders lack a professional habit of formal modeling. We report observations from student design teams as well as two case studies, respectively of a prototype for supporting creative communication to design objects, and of stakeholder-involvement in early design. In all observations and case studies we found that non-formal techniques supported strong collaboration resulting in deep understanding of early design ideas, of their value and of the feasibility of solutions.

Numerical modelling and design of lipped channel beams subject to shear

Cold-formed steel members are increasingly used as primary structural elements in buildings due to the availability of thin and high strength steels and advanced cold-forming technologies. Cold-formed lipped channel beams (LCB) are commonly used as flexural members such as floor joists and bearers. Many research studies have been carried out to evaluate the behaviour and design of LCBs subject to pure bending actions. However, limited research has been undertaken on the shear behaviour and strength of LCBs. Hence a numerical study was undertaken to investigate the shear behaviour and strength of LCBs. Finite element models of simply supported LCBs with aspect ratios of 1.0 and 1.5 were considered under a mid-span load. They were then validated by comparing their results with test results and used in a detailed parametric study based on the validated finite element models. Numerical studies were conducted to investigate the shear buckling and post-buckling behaviour of LCBs. Experimental and numerical results showed that the current design rules in cold-formed steel structures design codes are very conservative for the shear design of LCBs. Improved design equations were therefore proposed for the shear strength of LCBs. This paper presents the details of this numerical study of LCBs and the results.

Rational design of artificial cellular niches for tissue engineering

Tissue Engineering is a promising emerging field that studies the intrinsic regenerative potential of the human body and uses it to restore functionality of damaged organs or tissues unable of self-healing due to illness or ageing. In order to achieve regeneration using Tissue Engineering strategies, it is first necessary to study the properties of the native tissue and determine the cause of tissue failure; second, to identify an optimum population of cells capable of restoring its functionality; and third, to design and manufacture a cellular microenvironment in which those specific cells are directed towards the desired cellular functions. The design of the artificial cellular niche has a tremendous importance, because cells will feel and respond to both its biochemical and biophysical properties very differently. In particular, the artificial niche will act as a physical scaffold for the cells, allowing their three-dimensional spatial organization; also, it will provide mechanical stability to the artificial construct; and finally, it will supply biochemical and mechanical cues to control cellular growth, migration, differentiation and synthesis of natural extracellular matrix. During the last decades, many scientists have made great contributions to the field of Tissue Engineering. Even though this research has frequently been accompanied by vast investments during extended periods of time, yet too often these efforts have not been enough to translate the advances into new clinical therapies. More and more scientists in this field are aware of the need of rational experimental designs before carrying out complex, expensive and time-consuming in vitro and in vivo trials. This review highlights the importance of computer modeling and novel biofabrication techniques as critical key players for a rational design of artificial cellular niches in Tissue Engineering.

Design, characterisation and in vivo testing of a new, adjustable stiffness, external fixator for the rat femur

Very little is known about the infl uence of the mechanical environment on the healing of large segmental defects. This partly reflects the lack of standardised, well characterised technologies to enable such studies. Here we report the design, construction and characterisation of a novel external fixator for use in conjunction with rat femoral defects. This device not only imposes a predetermined axial stiffness on the lesion, but also enables the stiffness to be changed during the healing process. The main frame of the fi xator consists of polyethylethylketone with titanium alloy mounting pins. The stiffness of the fi xator is determined by interchangeable connection elements of different thicknesses. Fixators were shown to stabilise 5 mm femoral defects in rats in vivo for at least 8 weeks during unrestricted cage activity. No distortion or infections, including pin infections, were noted. The healing process was simulated in vitro by inserting into a 5 mm femoral defect, materials whose Young’s moduli approximated those of the different tissues present in regenerating bone. These studies confirmed that, although the external fixator is the major determinant of axial stiffness during the early phase of healing, the regenerate within the lesion subsequently dominates this property. There is much clinical interest in altering the mechanics of the defect to enhance bone healing. Our data suggest that, if alteration of the mechanical environment is to be used to modulate the healing of large segmental defects, this needs to be performed before the tissue properties become dominant.

Design of a garment for data collection of toddler language and physical activity

Design process phases of development, evaluation and implementation were used to create a garment to simultaneously collect reliable data of speech production and intensity of movement of toddlers (18-36 months). A series of prototypes were developed and evaluated that housed accelerometer-based motion sensors and a digital transmitter with microphone. The approved test garment was a top constructed from loop-faced fabric with interior pockets to house devices. Extended side panels allowed for sizing. In total, 56 toddlers (28 male; 28 female; 16-36 months of age) participated in the study providing pilot and baseline data. The test garment was effective in collecting data as evaluated for accuracy and reliability using ANOVA for accelerometer data, transcription of video for type of movement, and number and length of utterances for speech production. The data collection garment has been implemented in various studies across disciplines.

Studies on the in-plane shear response of confined masonry shear walls

The prime aim of this research project is to evaluate the performance of confined masonry walls under in-plane shear with a view to contributing to the national masonry design standard through a set of design clauses. This aim stems from the criticisms of the current provisions of the in-plane shear capacity equations in the Australian Masonry Standard AS3700 (2011) being highly non-conservative. This PhD thesis is an attempt to address this gap in the knowledge through systematic investigation of the key parameters that affects the in-plane shear strength of the masonry walls through laboratory experiments and extensive finite element analyses.

Hip and knee kinematics display complex and time-varying sagittal kinematics during repetitive stepping: Implications for design of a functional fatigue model of the knee extensors and flexors

The validity of fatigue protocols involving multi-joint movements, such as stepping, has yet to be clearly defined. Although surface electromyography can monitor the fatigue state of individual muscles, the effects of joint angle and velocity variation on signal parameters are well established. Therefore, the aims of this study were to i) describe sagittal hip and knee kinematics during repetitive stepping ii) identify periods of high inter-trial variability and iii) determine within-test reliability of hip and knee kinematic profiles. A group of healthy men (N = 15) ascended and descended from a knee-high platform wearing a weighted vest (10%BW) for 50 consecutive trials. The hip and knee underwent rapid flexion and extension during step ascent and descent. Variability of hip and knee velocity peaked between 20-40% of the ascent phase and 80-100% of the descent. Significant (p<0.05) reductions in joint range of motion and peak velocity during step ascent were observed, while peak flexion velocity increased during descent. Healthy individuals use complex hip and knee motion to negotiate a knee-high step with kinematic patterns varying across multiple repetitions. These findings have important implications for future studies intending to use repetitive stepping as a fatigue model for the knee extensors and flexors.

Livable housing design : the voluntary provision of inclusive housing in Australia

This paper reports on a study of the voluntary provision of inclusive housing. The impetus for the study is the Livable Housing Design initiative, an agreement among Australian housing industry and community leaders in 2010 to a national guideline and voluntary strategy with a target to provide minimum access features in all new housing by 2020. Situated in and around Brisbane, Australia, the study problematises the assumption that the housing industry will respond voluntarily; an assumption which this study concludes is unfounded. The Livable Housing Design initiative asks individual agents to consider the needs of people beyond the initial contract, to proceed with objective reasoning and to do the right thing voluntarily. Instead, the study found that interviewees focused on their immediate contractual obligations, were reluctant to change established practices and saw little reason to do more than was legally required of them. This paper argues that the highly-competitive and risk-averse nature of the industry works against a voluntary approach for inclusive housing and, if the 2020 target of the Livable Housing Design initiative is to be reached, a mandated approach through legislation will be necessary. The Livable Housing Design initiative, however, has an important role to play in preparing the Australian housing industry to accept further regulation.

Key facilitators and barriers to quality of life in residential aged care : the role of design

Australia is undergoing a critical demographic transition: the population is ageing. By 2050, one in four Australians will be older than 65 years and by 2031, the number of older Australians requiring residential aged care will increase 63%, to 1.4 million (ABS, 2005). In anticipation of this global demographic transition, the World Health Organisation has advocated ‘active ageing’, identifying health, participation and security as the three key factors that enhance quality of life for people as they age (WHO, 2002). While there is considerable discussion and acceptance of active ageing principles, little is known about the experience of ‘active ageing’ for older Australians who live in Residential Aged Care Facilities (RACF). This research addresses this knowledge gap by exploring the key facilitators and barriers to quality of life and active ageing in aged care from the perspective of aged care residents (n=12). To do this, the project documented the initial expectations and daily life experience of new residents living in a RACF over a one-year period. Combined with in-depth interviews and surveys, the project utilised Photovoice methodology - where participants used photography to record their lived experiences. The initial findings suggest satisfaction with living in aged care centers around five key themes; resident’s mental attitude to living in aged care, forming positive peer and staff relationships, self-determination and maintaining independence, opportunities to participate in interesting activities, and living in a safe and comfortable physical environment. This paper reports on the last of these five key themes, focusing on the role of design in facilitating quality of life, specifically: “living within these walls” – safety, comfort and the physical environment.