995 resultados para Open-pore polyurethane
Resumo:
Machine learning has become a valuable tool for detecting and preventing malicious activity. However, as more applications employ machine learning techniques in adversarial decision-making situations, increasingly powerful attacks become possible against machine learning systems. In this paper, we present three broad research directions towards the end of developing truly secure learning. First, we suggest that finding bounds on adversarial influence is important to understand the limits of what an attacker can and cannot do to a learning system. Second, we investigate the value of adversarial capabilities-the success of an attack depends largely on what types of information and influence the attacker has. Finally, we propose directions in technologies for secure learning and suggest lines of investigation into secure techniques for learning in adversarial environments. We intend this paper to foster discussion about the security of machine learning, and we believe that the research directions we propose represent the most important directions to pursue in the quest for secure learning.
Resumo:
Railway timetabling is an important process in train service provision as it matches the transportation demand with the infrastructure capacity while customer satisfaction is also considered. It is a multi-objective optimisation problem, in which a feasible solution, rather than the optimal one, is usually taken in practice because of the time constraint. The quality of services may suffer as a result. In a railway open market, timetabling usually involves rounds of negotiations among a number of self-interested and independent stakeholders and hence additional objectives and constraints are imposed on the timetabling problem. While the requirements of all stakeholders are taken into consideration simultaneously, the computation demand is inevitably immense. Intelligent solution-searching techniques provide a possible solution. This paper attempts to employ a particle swarm optimisation (PSO) approach to devise a railway timetable in an open market. The suitability and performance of PSO are studied on a multi-agent-based railway open-market negotiation simulation platform.
Resumo:
For the filling and reconstruction of non-healing bone defects, the application of porous ceramic scaffold as bone substitutes is considered to be a reasonable choice. In bone tissue engineering, an ideal scaffold must satisfy several criterias such as open porosity, having high compressive strength (it depends where in body, and if external fixatures are used) and the practicability for cell migration. Many researchers have focused on enhancing the mechanical properties of hydroxyapatite scaffolds by combining it with other biomaterials, such as bioglass and polymers. Nevertheless, there is still a lack of suitable scaffolds based on porous biomaterials. In this study, zirconia scaffolds from two different templates (polyurethane (PU) and Acrylonitrile Butadiene Styrene (ABS) templates) were successfully fabricated with dissimilar fabrication techniques. The scaffold surfaces were further modified with mesoporous bioglass for the purpose of bone tissue engineering. In the study of PU template scaffold, high porosity (~88%) sol-gel derived yttria-stabilized zirconia (YSZ) scaffold was prepared by a polyurethane (PU) foam replica method using sol-gel derived zirconia for the first time, and double coated with Mesoporous Bioglass (MBGs) coating. For the ABS template scaffold, two types of templates (cube and cylinder) with different strut spacings were used and fabricated by a 3D Rapid Prototyper. Subsequently, zirconia scaffolds with low porosity (63±2.8% to 68±2.5%) were fabricated by embedding the zirconia powder slurry into the ABS templates and burning out the ABS to produce a uniform porous structure. The zirconia scaffolds were double coated with mesoporous bioglass by dip coating for the first time. The porosities of the scaffolds were calculated before and after coating. The microstructures were then examined using scanning electron microscopy and the mechanical properties were evaluated using compressive test. Accordingly, relationships between microstructure, processing and mechanical behaviour of the porous zirconia was discussed. Scaffold biocompatibility and bioactivity was also evaluated using a bone marrow stromal cell (BMSC) proliferation test and a simulated body fluid test.
Resumo:
Open-source software systems have become a viable alternative to proprietary systems. We collected data on the usage of an open-source workflow management system developed by a university research group, and examined this data with a focus on how three different user cohorts – students, academics and industry professionals – develop behavioral intentions to use the system. Building upon a framework of motivational components, we examined the group differences in extrinsic versus intrinsic motivations on continued usage intentions. Our study provides a detailed understanding of the use of open-source workflow management systems in different user communities. Moreover, it discusses implications for the provision of workflow management systems, the user-specific management of open-source systems and the development of services in the wider user community.
Resumo:
A better understanding of Open Source Innovation in Physical Product (OSIP) might allow project managers to mitigate risks associated with this innovation model and process, while developing the right strategies to maximise OSIP outputs. In the software industry, firms have been highly successful using Open Source Innovation (OSI) strategies. However, OSI in the physical world has not been studied leading to the research question: What advantages and disadvantages do organisations incur from using OSI in physical products? An exploratory research methodology supported by thirteen semi-structured interviews helped us build a seven-theme framework to categorise advantages and disadvantages elements linked with the use of OSIP. In addition, factors impacting advantage and disadvantage elements for firms using OSIP were identified as: „h Degree of openness in OSIP projects; „h Time of release of OSIP in the public domain; „h Use of Open Source Innovation in Software (OSIS) in conjunction with OSIP; „h Project management elements (Project oversight, scope and modularity); „h Firms. Corporate Social Responsibility (CSR) values; „h Value of the OSIP project to the community. This thesis makes a contribution to the body of innovation theory by identifying advantages and disadvantages elements of OSIP. Then, from a contingency perspective it identifies factors which enhance or decrease advantages, or mitigate/ or increase disadvantages of OSIP. In the end, the research clarifies the understanding of OSI by clearly setting OSIP apart from OSIS. The main practical contribution of this paper is to provide manager with a framework to better understand OSIP as well as providing a model, which identifies contingency factors increasing advantage and decreasing disadvantage. Overall, the research allows managers to make informed decisions about when they can use OSIP and how they can develop strategies to make OSIP a viable proposition. In addition, this paper demonstrates that advantages identified in OSIS cannot all be transferred to OSIP, thus OSIP decisions should not be based upon OSIS knowledge.
Resumo:
This paper describes modelling, estimation and control of the horizontal translational motion of an open-source and cost effective quadcopter — the MikroKopter. We determine the dynamics of its roll and pitch attitude controller, system latencies, and the units associated with the values exchanged with the vehicle over its serial port. Using this we create a horizontal-plane velocity estimator that uses data from the built-in inertial sensors and an onboard laser scanner, and implement translational control using a nested control loop architecture. We present experimental results for the model and estimator, as well as closed-loop positioning.
Resumo:
The Malaysian National Innovation Model blueprint states that there is an urgent need to pursue an innovation-oriented economy to improve the nation’s capacity for knowledge, creativity and innovation. In nurturing a pervasive innovation culture, the Malaysian government has declared the year 2010 as an Innovative Year whereby creativity among its population is highly celebrated. However, while Malaysian citizens are encouraged to be creative and innovative, scientific data and information generated from publicly funded research in Malaysia is locked up because of rigid intellectual property licensing regimes and traditional publishing models. Reflecting on these circumstances, this paper looks at, and argue why, scientific data and information should be made available, accessible and re-useable freely to promote the grassroots level of innovation in Malaysia. Using innovation theory as its platform of argument, this paper calls for an open access policy for publicly funded research output to be adopted and implemented in Malaysia. Simultaneously, a normative analytic approach is used to determine the types of open access policy that ought to be adopted to spur greater innovation among Malaysians.
Resumo:
This special issue of the Journal of Urban Technology brings together five articles that are based on presentations given at the Street Computing workshop held on 24 November 2009 in Melbourne in conjunction with the Australian Computer-Human Interaction conference (OZCHI 2009). Our own article introduces the Street Computing vision and explores the potential, challenges and foundations of this research vision. In order to do so, we first look at the currently available sources of information and discuss their link to existing research efforts. Section 2 then introduces the notion of Street Computing and our research approach in more detail. Section 3 looks beyond the core concept itself and summarises related work in this field of interest.
Resumo:
Purpose - Thermo-magnetic convection and heat transfer of paramagnetic fluid placed in a micro-gravity condition (g = 0) and under a uniform vertical gradient magnetic field in an open square cavity with three cold sidewalls have been studied numerically. Design/methodology/approach - This magnetic force is proportional to the magnetic susceptibility and the gradient of the square of the magnetic induction. The magnetic susceptibility is inversely proportional to the absolute temperature based on Curie’s law. Thermal convection of a paramagnetic fluid can therefore take place even in zero-gravity environment as a direct consequence of temperature differences occurring within the fluid due to a constant internal heat generation placed within a magnetic field gradient. Findings - Effects of magnetic Rayleigh number, Ra, Prandtl number, Pr, and paramagnetic fluid parameter, m, on the flow pattern and isotherms as well as on the heat absorption are presented graphically. It is found that the heat transfer rate is suppressed in increased of the magnetic Rayleigh number and the paramagnetic fluid parameter for the present investigation. Originality/value - It is possible to control the buoyancy force by using the super conducting magnet. To the best knowledge of the author no literature related to magnetic convection for this configuration is available.