Propagation characteristics of lamb waves in stringer-stiffened panels

Stringer-stiffened plate-like structure is a typical engineering structure and its structural integrity is critical. A guided Lamb wave-based damage identification scheme and an online structural health monitoring (SHM) system with an integrated PZT-sensor network were developed. In the previous studies, the specimens were relatively simple. In this paper, the above mentioned method was extended to the stiffened plate-like structure—a flat plate reinforced by stringer. FE dynamic simulation was applied to investigate the Lamb wave propagation characteristics due to the existence of stringer with the consideration of its material and geometric configurations.

Gambling, society and the evolution of risk-taking

Gambling is emerging as a major industry around the world at a time when many of the more traditional economic pursuits are becoming less productive, but while the burgeoning gambling industry is certainly profitable and provides good investment opportunities and economic benefits for business and communities alike, it is timely that we look more closely at the overall benefits and costs of this phenomenon in modern society.

In this book about the modern gambling business, a motif of the Colorado River and the Boulder/Hoover Dam is explored in the opening section, likening the benefits and risks of gambling to those of the damming of the Colorado to irrigate California. There can be no doubt that the project wrested many Americans from poverty and unemployment in the depression, built a world-leading engineering structure that served to help the desert bloom, so to speak, including, of course, the re-making of Las Vegas. With the wisdom of hindsight and our increasing environmental awareness, the choking of the Colorado has had its downsides as does the gambling industry as we already know.

From the metaphorical re-examination of Fear and Loathing in Las Vegas, this current book focuses on some of the central aspects of the gambling industry in Australia and around the world, exploring how the industry is traveling in the 21st Century and asking why we are becoming so pre-occupied at this time with the processes of gambling. The prevalence of problem gambling is discussed; the numbers and how they are measured, along with various approaches to treatment and remediation for people affected adversely by their gambling behaviour.

Beyond the ‘bricks and mortar’ gambling and the electronic gaming machines of the latter part of the twentieth century, however, the development of new on-line gambling technologies is introducing different types of products, inducting new consumers to gambling products, changing the face of gambling in society, driving greater profits and potentially spawning more associated problems. While we are still struggling to understand the mechanisms through which more traditional gambling mechanisms affect consumers of these products and how best to remediate or treat such problems, a new form of the gambling phenomenon is being loosed upon modern consumers.

To return to the Hoover Dam metaphor; perhaps this new flood will be too strong for the dam or perhaps it will bring profits and benefits for all concerned. Before we can arrive at a decision about such potential costs and benefits, however, it will be important for us to see just whose money fuels this next phase of industry expansion and whether the profits of the industry are won at the cost of people with gambling problems; people who can’t afford to play the game, let along lose. Will the players in Macau, Singapore, Hong Kong, Vegas, Atlantic City, Sydney and other emerging markets in Asia, along with the new generation of consumers of on-line gambling products, at the end of the day see that their play has been worth the price paid or will the losses to individuals and communities out-weigh the benefits that flow, paradoxically, from this complex industry?

Architecture and engineering of a supramolecular functional material by manipulating the nano-structure of fiber network

Three-dimensional fiber networks were created from an organogel system consisting mainly of elongated fibrils by using a nonionic surfactant as an additive. The presence of the surfactant molecules manipulates the network structure by enhancing the mismatch nucleation on the growing fiber tips. Both the fiber network structure and the rheological properties of the material can be finely tuned by changing the surfactant concentration, which provides a robust approach to the engineering of supramolecular soft functional materials.

Eiffel assertions and the external structure of classes and objects

The “external structure” in an object oriented system refers here to the  graphs of objects and classes. The class structure graph or class model is derived from the object structure graph or object model, and in this operation structural information is lost, or never made explicit. Although object oriented programming languages capture the class model as declarations,  contradictory assumptions about object model properties may be made introducing faults into the design. Consistent assumptions about the object model can be specified in the code using assertions such as Eiffel’s  invariants, preconditions and postconditions. Three examples specifying the external structure are considered.

Issues in IT service-oriented requirements engineering

Corporate information technology (IT) management is increasingly service-oriented, offering continuous evaluation and improvement of application, communication, delivery and support services to internal and external customers. Service-oriented requirements engineering (SoRE) plays a significant role in identifying and specifying service requirements, formally defined through service-level agreements (SLAs). However, the new frameworks and approaches emerging to guide these developments have not yet addressed how requirements for such services can be effectively developed, nor identified the diverse issues involved. We report a case study of a web services team development of requirements for an internal Service Desk service. The study revealed five main issues of concern when developing service provider requirements: service roles, responsibilities and accountability; service performance metrics; resolution of conflicting stakeholder service requirements; customer acceptance of service change; and service provider team structure. This study suggests that in the new IT services era, new techniques and approaches are needed for eliciting and determining provider and customer requirements that involve key stakeholder groups equitably and more closely negotiate the sometimes-conflicting provider and customer needs.

Requirements engineering during global software development : some impediments to the requirements engineering process : a case study

Requirements engineering is not straightforward for any software development team. Developing software when team members are located in widely distributed geographic locations poses many challenges for developers, particularly during the requirements engineering phase. This paper reports on a case study concerning a large software development project that was completed in just seven months between users located in the UK and software developers from an international software house based in New Zealand. The case indicates that while “true” global requirements engineering may be desirable in achieving economy of resources, a “hybrid” structure of requirements engineering processes is more realistic so that lasting relationships with clients may be formed, and requirements engineering activities achieved. The main impediment to the process of requirements engineering during global software development, as recounted by the team members in this case, is communication. Communication issues may be further described in terms of four categories: distribution of the clients and the development team, distribution of the development team, cultural differences between the clients and the development team and cultural differences among the development team.

Shape memory alloy scaffolds for bone tissue engineering

Titanium alloy scaffolds for bone tissue engineering are receiving increasing attention because their porous structure and mechanical properties can be adjusted to match those of bone. In particular, there is an enormous potential to increase the life of such implant material if the porous structure can be imparted with shape memory properties. In the present study, TiNi scaffolds with a porous structure and high porosities up to 75% were fabricated by powder metallurgy. The porous structure was characterized by scanning electron microscope. The mechanical properties, the shape memory and superelastic effects were investigated by differential scanning calorimetry, nanoindentation and compressive tests. Results indicate that the porous TiNi scaffolds display an open-cell porous structure which provides new bone tissue ingrowth ability. The mechanical properties of the TiNi scaffolds can be tailored to match those of natural bone. Furthermore, the TiNi scaffolds show good shape memory and superelastic effects.

Titanium–nickel shape memory alloy foams for bone tissue engineering

Titanium–nickel (TiNi) shape memory alloy (SMA) foams with an open-cell porous structure were fabricated by space-holder sintering process and characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The mechanical properties and shape memory properties of the TiNi foam samples were investigated using compressive test. Results indicate that the plateau stresses and elastic moduli of the foams under compression decrease with the increase of their porosities. The plateau stresses and elastic moduli are measured to be from 1.9 to 38.3 MPa and from 30 to 860 MPa for the TiNi foam samples with porosities ranged from 71% to 87%, respectively. The mechanical properties of the TiNi alloy foams can be tailored to match those of bone. The TiNi alloy foams exhibit shape memory effect (SME), and it is found that the recoverable strain due to SME decreases with the increase of foam porosity.

Ti6Ta4Sn alloy and subsequent scaffolding for bone tissue engineering

Porous titanium (Ti) and titanium alloys are promising scaffold biomaterials for bone tissue engineering, because they have the potential to provide new bone tissue ingrowth abilities and low elastic modulus to match that of
natural bone. In the present study, a new highly porous Ti6Ta4Sn alloy scaffold with the addition of biocompatible alloying elements (tantalum (Ta) and tin (Sn)) was prepared using a space-holder sintering method. The
strength of the Ti6Ta4Sn scaffold with a porosity of 75% was found to be significantly higher than that of a pure Ti scaffold with the same porosity. The elastic modulus of the porous alloy can be customized to match that of
human bone by adjusting its porosity. In addition, the porous Ti6Ta4Sn alloy exhibited an interconnected porous structure, which enabled the ingrowth of new bone tissues. Cell culture results revealed that human SaOS₂
osteoblast-like cells grew and spread well on the surfaces of the solid alloy, and throughout the porous scaffold. The surface roughness of the alloy showed a significant effect on the cell behavior, and the optimum surface
roughness range for the adhesion of the SaOS2 cell on the alloy was 0.15 to 0.35 mm. The present study illustrated the feasibility of using the porous Ti6Ta4Sn alloy scaffold as an orthopedic implant material with a special
emphasis on its excellent biomechanical properties and in vitro biocompatibility with a high preference by osteoblast-like cells.

Analysis of twelve electrical and electronics engineering programs

This paper investigates undergraduate programs in electrical and electronics engineering offered by twelve universities in Australia, Asia, Europe, and America. The investigation focuses on the structure and content of the programs, and the contact hour and assessment of the subjects involved in the programs. The investigation is carried out in four stages: selection of universities, collection of data, analysis of data, and formulation of outcomes. A list of subjects is created based on the content of the programs. The average percentage coverage of each subject in the twelve programs is calculated. The subjects are then grouped into nine program components. The average percentage coverage of each component per university is calculated. For each component, the total number of contact hours for lecture, tutorial, and practical is calculated. Also, the average percentage of four assessment methods for each component is found. Discussions on the outcome of the investigation are presented.

Inter-bonded fibrous matrices for 3D tissue engineering scaffolds

The thesis established a stable three-dimensional fibrous tissue scaffold that has controlled pore structure and inter-bonded fibrous structure, and also examined the effects of the 3D fibrous matrices and functional surfaces including nano-scale topography, bioactive CaP coating and antibacterial treatment on the cell growth behavior for tissue engineering application.