A porous crystal plasticity constitutive model for ductile deformation and failure in porous single crystals

The author thankfully acknowledges the financial support of EPSRC funding (EP/ L021714/1).Peer reviewedPostprin

SHAREDWEALTH: A CRYPTOCURRENCY TO REWARD MINERS EVENLY

Bitcoin [19] is a decentralized cryptocurrency that has recently gained popularity and has emerged as a popular medium of exchange. The total market capitalization is around 1.5 billion US dollars as of October 2013 [28]. All the operations of Bitcoin are maintained in a distributed public global ledger known as a block chain which consists of all the successful transactions that have ever taken place. The security of a block chain is maintained by a chain of cryptographic puzzles solved by participants called miners, who in return are rewarded with bitcoins. To be successful, the miner has to put in his resources to solve the cryptographic puzzle (also known as a proof of work). The reward structure is an incentive for miners to contribute their computational resources and is also essential to the currency\u27s decentralized nature. One disadvantage of the reward structure is that the payment system is uneven. The reward is always given to one person. Hence people form mining pools where every member of the pool solves the same cryptographic puzzle and irrespective of the person who solved it, the reward is shared evenly among all the members of the pool. The Bitcoin protocol assumes that the miners are honest and they follow the Bitcoin protocol as prescribed. If group of selfish miners comes to lead by forming pools, the currency stops being decentralized and comes under the control of the selfish miners. Such miners can control the whole Bitcoin network [29]. Our goal is to address this problem by creating a distinct peer-to-peer protocol that reduces the incentives for the miners to join large mining pools. The central idea is to pay the “runners-up” who come close to finding a proof, thereby creating a less volatile payout situation. The work done by the “runners-up” can be used by other miners to find the solution of proof of work by building upon their work. Once they find the actual solution they have to include the solution of the other miner in order to get rewarded. The benefit of this protocol is that not only the miners save their computational resources but also the reward is distributed among the miners

Defining pro-poor growth

.Poverty, pro-poor

A multiscale constitutive model for intergranular stress corrosion cracking in type 304 austenitic stainless steel

Intergranular stress corrosion cracking (IGSCC) is a fracture mechanism in sensitised austenitic stainless steels exposed to critical environments where the intergranular cracks extends along the network of connected susceptible grain boundaries. A constitutive model is presented to estimate the maximum intergranular crack growth by taking into consideration the materials mechanical properties and microstructure characters distribution. This constitutive model is constructed based on the assumption that each grain is a two phase material comprising of grain interior and grain boundary zone. The inherent micro-mechanisms active in the grain interior during IGSCC is based on crystal plasticity theory, while the grain boundary zone has been modelled by proposing a phenomenological constitutive model motivated from cohesive zone modelling approach. Overall, response of the representative volume is calculated by volume averaging of individual grain behaviour. Model is assessed by performing rigorous parametric studies, followed by validation and verification of the proposed constitutive model using representative volume element based FE simulations reported in the literature. In the last section, model application is demonstrated using intergranular stress corrosion cracking experiments which shows a good agreement

A multiscale constitutive model for intergranular stress corrosion cracking in type 304 austenitic stainless steel

Peer reviewedPublisher PD

A multiscale constitutive model for intergranular stress corrosion cracking in type 304 austenitic stainless steel

Intergranular stress corrosion cracking (IGSCC) is a fracture mechanism in sensitised austenitic stainless steels exposed to critical environments where the intergranular cracks extends along the network of connected susceptible grain boundaries. A constitutive model is presented to estimate the maximum intergranular crack growth by taking into consideration the materials mechanical properties and microstructure characters distribution. This constitutive model is constructed based on the assumption that each grain is a two phase material comprising of grain interior and grain boundary zone. The inherent micro-mechanisms active in the grain interior during IGSCC is based on crystal plasticity theory, while the grain boundary zone has been modelled by proposing a phenomenological constitutive model motivated from cohesive zone modelling approach. Overall, response of the representative volume is calculated by volume averaging of individual grain behaviour. Model is assessed by performing rigorous parametric studies, followed by validation and verification of the proposed constitutive model using representative volume element based FE simulations reported in the literature. In the last section, model application is demonstrated using intergranular stress corrosion cracking experiments which shows a good agreement

PARENTAL EXPERIENCES PARTICIPATING IN THE POSITIVE BEHAVIOR INTERVENTION AND SUPPORT PROCESS IN SCHOOLS

The purpose of this study was to explore the experiences of parents of children with challenging behavior regarding their involvement with, and interest in, the Positive Behavior Intervention and Support (PBIS) process within school systems. The overarching research question was what are the lived (perceived) experiences of parents of children with challenging behavior regarding their involvement in the PBIS process? From this main question, there were five subsidiary questions that were addressed: How do parents of children with challenging behavior involved in the PBIS process describe their lived experiences? In what ways have parents made meaning out of their experiences of participation in PBIS interventions of their children with challenging behavior at school? What do parents consider to have been the risk and protective factors in their experiences in collaborating with schools on the PBIS process? How have the parents’ personal characteristics influenced their perceptions of the support they get from school systems in their collaboration on PBIS? How do parents evaluate the support they get from the school system during their involvement? In order to answer these research questions, the researcher used semi-structured interviews with parents of children with challenging behavior. Eight parents, who met the criteria of the research selection process, were interviewed. All the interviews were transcribed, coded, and analyzed. The coding and analysis of the eight interviews was informed and guided by the constructivism paradigm of qualitative inquiry called constructivist grounded theory. The five major themes that emerged from the interviews were: (a) parental motivation to be involved in PBIS with the school systems, (b) parents’ roles and support to schools in implementing PBIS, (c) school collaboration for successful implementation of PBIS, (d) school collaboration for successful implementation, and (e) parents’ motivation for collaborating with schools. The findings revealed that the parents had limited knowledge regarding PBIS, played limited roles in supporting PBIS implementation because of lack of knowledge and communication with schools, were highly motivated to be involved in PBIS, and faced several barriers in working with schools. Overall, the findings were consistent with current research and added to the limited literature on the experience of families of children with challenging behavior in the implementation of PBIS. The findings could promote collaboration between parents of children with challenging behavior and the school systems in the PBIS process thereby improving the behavioral, and ultimately, the academic outcomes of children with challenging behavior. The study helped identify areas in need of further research such as the type of training that the parents need in implementing PBIS in the home environment. Practical implications of the findings are provided and discussed

Smooth particle hydrodynamics study of surface defect machining for diamond turning of silicon

Acknowledgments The authors would like to thank EPSRC (EP/K018345/1) and Royal Society-NSFC International Exchange Scheme for providing financial support to this research.Peer reviewedPublisher PD