A bridging transition technique for the combination of meshfree method with finite element method in 2D solids and structures

For certain continuum problems, it is desirable and beneficial to combine two different methods together in order to exploit their advantages while evading their disadvantages. In this paper, a bridging transition algorithm is developed for the combination of the meshfree method (MM) with the finite element method (FEM). In this coupled method, the meshfree method is used in the sub-domain where the MM is required to obtain high accuracy, and the finite element method is employed in other sub-domains where FEM is required to improve the computational efficiency. The MM domain and the FEM domain are connected by a transition (bridging) region. A modified variational formulation and the Lagrange multiplier method are used to ensure the compatibility of displacements and their gradients. To improve the computational efficiency and reduce the meshing cost in the transition region, regularly distributed transition particles, which are independent of either the meshfree nodes or the FE nodes, can be inserted into the transition region. The newly developed coupled method is applied to the stress analysis of 2D solids and structures in order to investigate its’ performance and study parameters. Numerical results show that the present coupled method is convergent, accurate and stable. The coupled method has a promising potential for practical applications, because it can take advantages of both the meshfree method and FEM when overcome their shortcomings.

Implication of 3D culture system for study of prostate cancer (CaP) mediated bone metastasis

Introduction : For the past decade, three dimensional (3D) culture has served as a foundation for regenerative medicine study. With an increasing awareness of the importance of cell-cell and cell-extracellular matrix interactions which are lacking in 2D culture system, 3D culture system has been employed for many other applications namely cancer research. Through development of various biomaterials and utilization of tissue engineering technology, many in vivo physiological responses are now better understood. The cellular and molecular communication of cancer cells and their microenvironment, for instance can be studied in vitro in 3D culture system without relying on animal models alone. Predilection of prostate cancer (CaP) to bone remains obscure due to the complexity of the mechanisms and lack of proper model for the studies. In this study, we aim to investigate the interaction between CaP cells and osteoblasts simulating the natural bone metastasis. We also further investigate the invasiveness of CaP cells and response of androgen sensitve CaP cells, LNCaP to synthetic androgen.----- Method : Human osteoblast (hOB) scaffolds were prepared by seeding hOB on medical grade polycaprolactone-tricalcium phosphate (mPLC-TCP) scaffolds and induced to produce bone matrix. CaP cell lines namely wild type PC3 (PC3-N), overexpressed prostate specific antigen PC3 (PC3k3s5) and LNCaP were seeded on hOB scaffolds as co-cultures. Morphology of cells was examined by Phalloidin-DAPI and SEM imaging. Gelatin zymography was performed on the 48 hours conditioned media (CM) from co-cultures to determine matrix metalloproteinase (MMP) activity. Gene expression of hOB/LNCaP co-cultures which were treated for 48 hours with 1nM synthetic androgen R1881 were analysed by quantitative real time PCR (qRT-PCR).----- Results : Co-culture of PCC/hOB revealed that the morphology of PCCs on the tissue engineered bone matrix varied from homogenous to heterogenous clusters. Enzymatically inactive pro-MMP2 was detected in CM from hOBs and PCCs cultured on scaffolds. Elevation in MMP9 activity was found only in hOB/PC3N co-culture. hOB/LNCaP co-culture showed increase in expression of key enzymes associated with steroid production which also corresponded to an increase in prostate specific antigen (PSA) and MMP9.----- Conclusions : Upregulation of MMP9 indicates involvement of ECM degradation during cancer invasion and bone metastases. Expression of enzymes involved in CaP progression, PSA, which is not expressed in osteoblasts, demonstrates that crosstalk between PCCs and osteoblasts may play a part in the aggressiveness of CaP. The presence of steroidogenic enzymes, particularly, RDH5, in osteoblasts and stimulated expression in co-culture, may indicate osteoblast production of potent androgens, fuelling cancer cell proliferation. Based on these results, this practical 3D culture system may provide greater understanding into CaP mediated bone metastasis. This allows the role of the CaP/hOB interaction with regards to invasive property and steroidogenesis to be further explored.

Initial steps in optimal planning of a distribution system

This paper reports the initial steps of research on planning of rural networks for MV and LV. In this paper, two different cases are studied. In the first case, 100 loads are distributed uniformly on a 100 km transmission line in a distribution network and in the second case, the load structure become closer to the rural situation. In case 2, 21 loads are located in a distribution system so that their distance is increasing, distance between load 1 and 2 is 3 km, between 2 and 3 is 6 km, etc). These two models to some extent represent the distribution system in urban and rural areas, respectively. The objective function for the design of the optimal system consists of three main parts: cost of transformers, and MV and LV conductors. The bus voltage is expressed as a constraint and should be maintained within a standard level, rising or falling by no more than 5%.

Defining the flammability of cylindrical metal rods through characterization of the thermal effects of the ignition promoter

All relevant international standards for determining if a metallic rod is flammable in oxygen utilize some form of “promoted ignition” test. In this test, for a given pressure, an overwhelming ignition source is coupled to the end of the test sample and the designation flammable or nonflammable is based upon the amount burned, that is, a burn criteria. It is documented that (1) the initial temperature of the test sample affects the burning of the test sample both (a) in regards to the pressure at which the sample will support burning (threshold pressure) and (b) the rate at which the sample is melted (regression rate of the melting interface); and, (2) the igniter used affects the test sample by heating it adjacent to the igniter as ignition occurs. Together, these facts make it necessary to ensure, if a metallic material is to be considered flammable at the conditions tested, that the burn criteria will exclude any region of the test sample that may have undergone preheating during the ignition process. A two-dimensional theoretical model was developed to describe the transient heat transfer occurring and resultant temperatures produced within this system. Several metals (copper, aluminum, iron, and stainless steel) and ignition promoters (magnesium, aluminum, and Pyrofuze®) were evaluated for a range of oxygen pressures between 0.69 MPa (100 psia) and 34.5 MPa (5,000 psia). A MATLAB® program was utilized to solve the developed model that was validated against (1) a published solution for a similar system and (2) against experimental data obtained during actual tests at the National Aeronautics and Space Administration White Sands Test Facility. The validated model successfully predicts temperatures within the test samples with agreement between model and experiment increasing as test pressure increases and/or distance from the promoter increases. Oxygen pressure and test sample thermal diffusivity were shown to have the largest effect on the results. In all cases evaluated, there is no significant preheating (above about 38°C/100°F) occurring at distances greater than 30 mm (1.18 in.) during the time the ignition source is attached to the test sample. This validates a distance of 30 mm (1.18 in.) above the ignition promoter as a burn length upon which a definition of flammable can be based for inclusion in relevant international standards (that is, burning past this length will always be independent of the ignition event for the ignition promoters considered here. KEYWORDS: promoted ignition, metal combustion, heat conduction, thin fin, promoted combustion, burn length, burn criteria, flammability, igniter effects, heat affected zone.

Virtual design process : design validation tool schematic approach in car carrier

An important aspect of designing any product is validation. Virtual design process (VDP) is an alternative to hardware prototyping in which analysis of designs can be done without manufacturing physical samples. In recent years, VDP have been generated either for animation or filming applications. This paper proposes a virtual reality design process model on one of the applications when used as a validation tool. This technique is used to generate a complete design guideline and validation tool of product design. To support the design process of a product, a virtual environment and VDP method were developed that supports validation and an initial design cycle performed by a designer. The product model car carrier is used as illustration for which virtual design was generated. The loading and unloading sequence of the model for the prototype was generated using automated reasoning techniques and was completed by interactively animating the product in the virtual environment before complete design was built. By using the VDP process critical issues like loading, unloading, Australian Design rules (ADR) and clearance analysis were done. The process would save time, money in physical sampling and to large extent in complete math generation. Since only schematic models are required, it saves time in math modelling and handling of bigger size assemblies due to complexity of the models. This extension of VDP process for design evaluation is unique and was developed, implemented successfully. In this paper a Toll logistics and J Smith and Sons car carrier which is developed under author’s responsibility has been used to illustrate our approach of generating design validation via VDP.

The Smart Skies Project

Smart Skies is an international research project exploring the development and demonstration of future aviation technologies which facilitate the more efficient utilisation of airspace for both manned and unmanned aircraft. These technologies include autonomous vision-based collision avoidance systems, autonomous airspace separation management systems and a mobile ground-based radar system to support non-segregated UAS operations within the NAS. This presentation will provide an introduction to the key programs of research, detail results from recent flight trial activities and will outline future directions for the project.

Designing interaction for local communications : an urban screen study

This paper discusses the ongoing design and use of a digital community noticeboard situated in a suburban hub. The design intention is to engage residents, collect and display local information and communications, and spark discussion. A key contribution is an understanding of Situated Display navigation that aids retrieval from a long-term collection created by and for suburban community, and engaging qualities of this collection.

Automatic Detection of Marine Mammal from Aerial Imagery

The following technical report describes the approach and algorithm used to detect marine mammals from aerial imagery taken from manned/unmanned platform. The aim is to automate the process of counting the population of dugongs and other mammals. We have developed and algorithm that automatically presents to a user a number of possible candidates of these mammals. We tested the algorithm in two distinct datasets taken from different altitudes. Analysis and discussion is presented in regards with the complexity of the input datasets, the detection performance.

Evaluation of separation management algorithms in Class G airspace

Use of Unmanned Aerial Vehicles (UAVs) in support of government applications has already seen significant growth and the potential for use of UAVs in commercial applications is expected to rapidly expand in the near future. However, the issue remains on how such automated or operator-controlled aircraft can be safely integrated into current airspace. If the goal of integration is to be realized, issues regarding safe separation in densely populated airspace must be investigated. This paper investigates automated separation management concepts in uncontrolled airspace that may help prepare for an expected growth of UAVs in Class G airspace. Not only are such investigations helpful for the UAV integration issue, the automated separation management concepts investigated by the authors can also be useful for the development of new or improved Air Traffic Control services in remote regions without any existing infrastructure. The paper will also provide an overview of the Smart Skies program and discuss the corresponding Smart Skies research and development effort to evaluate aircraft separation management algorithms using simulations involving realworld data communication channels, and verified against actual flight trials. This paper presents results from a unique flight test concept that uses real-time flight test data from Australia over existing commercial communication channels to a control center in Seattle for real-time separation management of actual and simulated aircraft. The paper also assesses the performance of an automated aircraft separation manager.

Parametric building development during early design stage

Objectives The objectives of this project were two-fold: • Assess the ease with which current architectural CAD systems supported the use ofparametric descriptions in defining building shape, engineering system performance and cost at the early stages of building design; • Assess the feasibility of implementing a software decision support system that allowed designers to trade-off the characteristics and configuration of various engineering systems to move towards a “global optimum” rather than considering each system in isolation and expecting humans to weigh up all of the costs and benefits. The first stage of the project consisted of using four different CAD systems to define building shells (envelopes) with different usages. These models were then exported into a shared database using the IFC information exchange specifications. The second stage involved the implementation of small computer programs that were able to estimate relevant system parameters based on performance requirements and the constraints imposed by the other systems. These are presented in a unified user interface that extracts the appropriate building shape parameters from the shared database Note that the term parametric in this context refers to the relationships among and between all elements of the building model - not just geometric associations - which will enable the desired coordination.

Development of diagnostic and prognostic algorithms for SF6 puffer circuit breakers from transient waveforms : a validation proposal

- This paper presents a validation proposal for development of diagnostic and prognostic algorithms for SF6 puffer circuit-breakers reproduced from actual site waveforms. The re-ignition/restriking rates are duplicated in given circuits and the cumulative energy dissipated in interrupters by the restriking currents. The targeted objective is to provide a simulated database for diagnosis of re-ignition/restrikes relating to the phase to earth voltage and the number of re-ignition/restrikes as well as estimating the remaining life of SF6 circuit-breakers. The model-based diagnosis of a tool will be useful in monitoring re-ignition/restrikes as well as predicting a nozzle’s lifetime. This will help ATP users with practical study cases and component data compilation for shunt reactor switching and capacitor switching. This method can be easily applied with different data for the different dielectric curves of circuit breakers and networks. This paper presents modelling details and some of the available cases, required project support, the validation proposal, the specific plan for implementation and the propsed main contributions.

A database ATP simulated waveforms of shunt reactor switching cases with vacuum breakers on motor circuits

This paper presents a database ATP (Alternative Transient Program) simulated waveforms for shunt reactor switching cases with vacuum breakers in motor circuits following interruption of the starting current. The targeted objective is to provide multiple reignition simulated data for diagnostic and prognostic algorithms development, but also to help ATP users with practical study cases and component data compilation for shunt reactor switching. This method can be easily applied with different data for the different dielectric curves of circuit-breakers and networks. This paper presents design details, discusses some of the available cases and the advantages of such simulated data.

Discussion Paper : Proposed CDIO Standard 13 - Internationalisation and Mobility

The benefits and growing need for international transparency in engineering qualifications, simple cross-credit processes, international dual awards and mechanisms to encourage student mobility, are receiving much attention around the world at present. In response, there are a number of global initiatives now looking at how these issues may be addressed, particularly in Europe, North America and Australia. CDIO has adopted 12 Standards as guiding principles for program reform and evaluation. The 12 CDIO Standards address program philosophy curriculum development, design-build experiences and workspaces, new methods of teaching and learning, faculty/academic development, and assessment and evaluation. However, none of the Standards address international qualifications nor student mobility. This discussion paper presents the underpinning case for introducing the 13th CDIO Standard, Internationalization and Mobility.

Evaluation of polycaprolactone scaffold degradation for 6 months in vitro and in vivo

The use of polycaprolactone (PCL) as a biomaterial, especially in the fields of drug delivery and tissue engineering, has enjoyed significant growth. Understanding how such a device or scaffold eventually degrades in vivo is paramount as the defect site regenerates and remodels. Degradation studies of three-dimensional PCL and PCL-based composite scaffolds were conducted in vitro (in phosphate buffered saline) and in vivo (rabbit model). Results up to 6 months are reported. All samples recorded virtually no molecular weight changes after 6 months, with a maximum mass loss of only about 7% from the PCL-composite scaffolds degraded in vivo, and a minimum of 1% from PCL scaffolds. Overall, crystallinity increased slightly because of the effects of polymer recrystallization. This was also a contributory factor for the observed stiffness increment in some of the samples, while only the PCL-composite scaffold registered a decrease. Histological examination of the in vivo samples revealed good biocompatibility, with no adverse host tissue reactions up to 6 months. Preliminary results of medical-grade PCL scaffolds, which were implanted for 2 years in a critical-sized rabbit calvarial defect site, are also reported here and support our scaffold design goal for gradual and late molecular weight decreases combined with excellent long-term biocompatibility and bone regeneration. (C) 2008 Wiley Periodicals, Inc. J Biomed Mater Res 90A: 906-919, 2009

A naturally shaped silicone ventricle evaluated in a mock circulation loop : a preliminary study

Mock circulation loops are used to evaluate the performance of cardiac assist devices prior to animal and clinical testing. A compressible, translucent silicone ventricle chamber that mimics the exact size, shape and motion of a failing heart is desired to assist in flow visualization studies around inflow cannulae during VAD support. The aim of this study was therefore to design and construct a naturally shaped flexible left ventricle and evaluate its performance in a mock circulation loop. The ventricle shape was constructed by the use of CT images taken from a patient experiencing cardiomyopathic heart failure and used to create a 3D image and subsequent mould to produce a silicone ventricle. Different cardiac conditions were successfully simulated to validate the ventricle performance, including rest, left heart failure and VAD support.