An Empirical Study of the Effectiveness of 'Forcing Diversity' Based on a Large Population of Diverse Programs

Use of diverse software components is a viable defence against common-mode failures in redundant softwarebased systems. Various forms of "Diversity-Seeking Decisions" (“DSDs”) can be applied to the process of developing, or procuring, redundant components, to improve the chances of the resulting components not failing on the same demands. An open question is how effective these decisions, and their combinations, are for achieving large enough reliability gains. Using a large population of software programs, we studied experimentally the effectiveness of specific "DSDs" (and their combinations) mandating differences between redundant components. Some of these combinations produced much better improvements in system probability of failure per demand (PFD) than "uncontrolled" diversity did. Yet, our findings suggest that the gains from such "DSDs" vary significantly between them and between the application problems studied. The relationship between DSDs and system PFD is complex and does not allow for simple universal rules (e.g. "the more diversity the better") to apply

ECONOMIC VALUATION ON CLIMATE CHANGE IN THE MARINE FISHERIES IN CILACAP, CENTRAL JAVA

The objective of this study is to estimate the impact of climate change in the marine capture fisheries in Cilacap, Central Java. Also to formulate the adaptation and mitigation strategies on the impacts of climate change. Data collection was done through multi-stages sampling. Samples of respondents were: 73 marine-fisher respondents, 43 collector respondents, and 100 consumer respondents, which were analyzed by descriptive statistics. In the aspect of production, there was a decrease in catch which caused severe losses in 26 respondents, an increase in length of trip which was vary from 1 day to 7 days, and changes in fishers spending, such as: change in cost of fuel, change in food & lodging cost, and change in productivity. Lack of production has led to a decrease in fish-stocks. Therefore availability and sustainability of fish-stock in the aspect of distribution became questionable, which influenced availability and affordability of fish in market (Aspect of consumption). Thus, enhancing the performance of extension institution was needed to anticipate the impact of climate change in marine fisheries sector. An ideal extension institution was made to enhance the performance of extension institution was made in order to estimate transaction cost of the policy. The result has shown the amount of information cost, policing cost and operational & maintenance cost to establish a successful program

Frame-Based Editing: Easing the Transition from Blocks to Text-Based Programming

Block-based programming systems, such as Scratch or Alice, are the most popular environments for introducing young children to programming. However, mastery of text-based programming continues to be the educational goal for stu- dents who continue to program into their teenage years and beyond. Transitioning across the significant gap between the two editing styles presents a difficult challenge in school- level teaching of programming. We propose a new style of program manipulation to bridge the gap: frame-based edit- ing. Frame-based editing has the resistance to errors and approachability of block-based programming while retaining the flexibility and more conventional programming seman- tics of text-based programming languages. In this paper, we analyse the issues involved in the transition from blocks to text and argue that they can be overcome by using frame- based editing as an intermediate step. A design and imple- mentation of a frame-based editor is provided

Cross-level sensor network simulation with COOJA

Simulators for wireless sensor networks are a valuable tool for system development. However, current simulators can only simulate a single level of a system at once. This makes system development and evolution difficult since developers cannot use the same simulator for both high-level algorithm development and low-level development such as device-driver implementations. We propose cross-level simulation, a novel type of wireless sensor network simulation that enables holistic simultaneous simulation at different levels. We present an implementation of such a simulator, COOJA, a simulator for the Contiki sensor node operating system. COOJA allows for simultaneous simulation at the network level, the operating system level, and the machine code instruction set level. With COOJA, we show the feasibility of the cross-level simulation approach