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Multiple piezoelectric power sources are used for extending the bandwidth or the multi-direction operation capability of the vibration harvesters. Typical rectifier configurations including parallel or series connection before a shared rectifier or one rectifier per source are usually used for regulating the multiple sources. The problem of charge cancelation arises for the shared rectifier configuration while diodes are too many for the configuration of one rectifier per source. In this article, improved rectifier design is proposed for multiple sources by introducing a common ground branch. The improved scalable rectifier design is capable of unifying more than one sources of different voltage polarity to power the load without charge cancelation, thus promising better performance than the aforementioned configurations. The power enhancement is verified through simulations and experiments with a maximum boost of 91.9% and the effective bandwidth is increased by 23.3% at least. In particular, the design has the advantage of cost saving by reducing the diodes to almost the half in comparison with the configuration of one rectifier per source.

The Critical Chain Scheduling and Buffer Management (CC/BM) methodology, proposed by Goldratt (Critical chain, 1997), introduced the concepts of feeding buffers, project buffers and resource buffers as well as the roadrunner mentality. This last concept, in which activities are started as soon as possible, was introduced in order to speed up projects by taking advantage of predecessors finishing early. Later on, the railway scheduling concept of never starting activities earlier than planned was introduced as a way to increase the stability of the project, typically at the cost of an increase in the expected project makespan. In this paper, we will indicate a realistic situation in which railway scheduling improves both the stability and the expected project makespan over roadrunner scheduling.

In previous research (Tian and Demeulemeester 2010), we have shown that in realistic situations railway scheduling improves both the stability and the expected project length over roadrunner scheduling. In this paper, we introduce the concept of resource flow networks in this analysis and determine what the impact of combining roadrunner or railway scheduling with priority lists or resource flow networks is on the average project length, the standard deviation of the project length, the timely project completion probability and the stability cost. Extensive computational results will be presented on both small and larger projects and a statistical analysis will be conducted by using SAS PROC GLM, indicating that in smaller projects the optimal combination strongly depends on the performance indicator of interest, while in larger projects a combination of roadrunner scheduling with a resource flow network seems optimal.

Critical chain project management, proposed by Goldratt, has proven to be a good methodology to schedule the resource-constrained projects in the past decades. Buffer management is one of the main features of the CCPM. There are a lot of researches about the buffer size methods, however not so much on the rescheduling after inserting the buffer. AS we know, there might be resource or precedence conflict after inserting the feeding buffer. It is the objective of this paper to introduce how to reschedule after inserting the buffer in the project. We propose two reschedule methodologies-local repaired reschedule and global reschedule to solve the resource and precedence contentions and some computation results are provided to compare those methodologies.

The Critical Chain Scheduling and Buffer Management (CC/BM) methodology, proposed by Goldratt (1997), introduced the concepts of feeding buffers, project buffers and resource buffers as well as the roadrunner mentality. This last concept, in which activities are started as soon as possible, was introduced in order to speed up projects by taking advantage of predecessors finishing early. Later on, the railway scheduling concept of never starting activities earlier than planned was introduced as a way to increase the stability of the project, typically at the cost of an increase in the expected project makespan. In this paper, we will indicate a realistic situation in which railway scheduling improves both the stability and the expected project makespan over roadrunner scheduling.

In previous research (Tian & Demeulemeester, 2010), we have shown that in realistic situations railway scheduling improves both the stability and the expected project length over roadrunner scheduling. In this paper, we introduce the concept of resource flow networks in this analysis and determine what the impact is of the resulting combinations on the average project length, the standard deviation of the project length, the timely project completion probability and the stability cost. Extensive computational results will be presented on both small and larger projects and statistic analysis will be conducted by using SAS PROC GLM.