title: Composing patterns to construct secure systems

authors: Rimba, Paul

subjects: security

abstract: Building secure applications requires significant expertise. Secure platforms and security patterns have been proposed to alleviate this problem. However, correctly applying patterns to use platform features is still highly expertise-dependent. Patterns are informal and there is a gap between them and platform features. We propose the concept of reusable verified design fragments, which package security patterns and platform features and are verified to provide assurance about their security properties. Design fragments can be composed through four primitive tactics. The verification of the composed design against desired security properties is presented in an assurance case. We demonstrate our approach by securing a Continuous Deployment pipeline and show that the tactics are sufficient to compose design fragments into a secure system. Finally, we formally define composition tactics, which are intended to support the development of systems that are secure by construction.

text: Composing patterns to construct secure systems Building secure applications requires significant expertise. Secure platforms and security patterns have been proposed to alleviate this problem. However, correctly applying patterns to use platform features is still highly expertise-dependent. Patterns are informal and there is a gap between them and platform features. We propose the concept of reusable verified design fragments, which package security patterns and platform features and are verified to provide assurance about their security properties. Design fragments can be composed through four primitive tactics. The verification of the composed design against desired security properties is presented in an assurance case. We demonstrate our approach by securing a Continuous Deployment pipeline and show that the tactics are sufficient to compose design fragments into a secure system. Finally, we formally define composition tactics, which are intended to support the development of systems that are secure by construction.

year: 2015

title: Development of an aluminium filled epoxy insert using perfactory rapid prototyping technique and electroless nickel plating for low volume plastic injection moulding

authors: Rajaguru, Janaka Chandraguptha

subjects: Rapid

abstract: In this research, a rapid tool for low volume production plastic injection moulding is designed, developed, and tested on an injection moulding machine. The tool is designed as a cavity insert of injection mould for plastic parts by an indirect rapid tooling approach. The plastic part is modelled in a CAD system and then built using a Perfactory rapid prototyping (RP) technique. Then a layer of nickel-phosphorous alloy is deposited on the prototype by electroless plating. This nickel plated RP model is then used as a casting pattern. A cavity insert, which is produced by using aluminium filled epoxy resin with the nickel plated casting pattern, is fabricated in a mould	base for injection moulding. Experimental testing on the cavity insert using an injection moulding machine show that the tool is producing quality parts without any noticeable deterioration of the surface. The number of shots completed using the cavity insert is more than 600.
Applying electroless nickel plating on the casting pattern made of rapid prototyping material was successful. It was found that pre-treatment processes are crucial. In addition, the rapid prototyping material cannot be plated with nickel without palladium activation and stannous sensitising. Results show that the deposited layer is uniform and composed of both nickel and phosphorous. The surface properties of the nickel and phosphorous deposit enhance the plated layer performance due to their low surface roughness and high lubrication characteristics. Moreover, the nickel-phosphorous layer also improves the surface hardness of the cavity insert since it is left on the cavity after the removal of the casting pattern. 
The cavity insert was installed on an industrial injection moulding machine for trials. Results show that the cavity insert performs well with Polyethylene at 170˚C at an injection pressure in the range of 80 ~ 100 bar. There are no signs of wear and tear on the cavity insert up to 620 shots. However, when the injection pressure is over 120 bar, cracks start developing in the cavity insert followed by catastrophic fracture. 
This research has shown that manufacturing an indirect rapid tooling using electroless nickel plating for low volume production of plastic injection mouldings is feasible for Perfactory produced RP models. The cavity insert can be fabricated using commonly available low cost materials within 48 hours.

text: Development of an aluminium filled epoxy insert using perfactory rapid prototyping technique and electroless nickel plating for low volume plastic injection moulding In this research, a rapid tool for low volume production plastic injection moulding is designed, developed, and tested on an injection moulding machine. The tool is designed as a cavity insert of injection mould for plastic parts by an indirect rapid tooling approach. The plastic part is modelled in a CAD system and then built using a Perfactory rapid prototyping (RP) technique. Then a layer of nickel-phosphorous alloy is deposited on the prototype by electroless plating. This nickel plated RP model is then used as a casting pattern. A cavity insert, which is produced by using aluminium filled epoxy resin with the nickel plated casting pattern, is fabricated in a mould	base for injection moulding. Experimental testing on the cavity insert using an injection moulding machine show that the tool is producing quality parts without any noticeable deterioration of the surface. The number of shots completed using the cavity insert is more than 600.
Applying electroless nickel plating on the casting pattern made of rapid prototyping material was successful. It was found that pre-treatment processes are crucial. In addition, the rapid prototyping material cannot be plated with nickel without palladium activation and stannous sensitising. Results show that the deposited layer is uniform and composed of both nickel and phosphorous. The surface properties of the nickel and phosphorous deposit enhance the plated layer performance due to their low surface roughness and high lubrication characteristics. Moreover, the nickel-phosphorous layer also improves the surface hardness of the cavity insert since it is left on the cavity after the removal of the casting pattern. 
The cavity insert was installed on an industrial injection moulding machine for trials. Results show that the cavity insert performs well with Polyethylene at 170˚C at an injection pressure in the range of 80 ~ 100 bar. There are no signs of wear and tear on the cavity insert up to 620 shots. However, when the injection pressure is over 120 bar, cracks start developing in the cavity insert followed by catastrophic fracture. 
This research has shown that manufacturing an indirect rapid tooling using electroless nickel plating for low volume production of plastic injection mouldings is feasible for Perfactory produced RP models. The cavity insert can be fabricated using commonly available low cost materials within 48 hours.

year: 2015

title: Rejoinder

authors: Kelly, Martin

abstract: Our paper (Kelly et al., 1999) set out to have points recognized as ‘needing to be addressed’ on the agendas of institutions currently providing accounting education. We believe that many institutions are continuing to fail to respond to recognized problems. We are grateful to the Commentators for recognizing our purpose. They note that our paper:
1. raises some important issues which need to be urgently addressed (Commentator 1);
2. illuminates why it is dif  cult to implement change even when there is a consensus to do so (Commentator 2);
3. provides a very important theme which has been neglected by many accounting educators (Commentator 3).

text: Rejoinder Our paper (Kelly et al., 1999) set out to have points recognized as ‘needing to be addressed’ on the agendas of institutions currently providing accounting education. We believe that many institutions are continuing to fail to respond to recognized problems. We are grateful to the Commentators for recognizing our purpose. They note that our paper:
1. raises some important issues which need to be urgently addressed (Commentator 1);
2. illuminates why it is dif  cult to implement change even when there is a consensus to do so (Commentator 2);
3. provides a very important theme which has been neglected by many accounting educators (Commentator 3).

year: 2000