Modular input-parallel-output-series DC/DC converter control with fault detection and redundancy

Large offshore wind farms will require an extensive sub-sea power network to provide internal interconnection. Present solutions are based around conventional medium-voltage AC architectures. This paper proposes an alternative DC collection network based around modular DC/DC converters with input-parallel-output-series (IPOS) connection. Small-signal analysis of the converter is presented, to assist in control scheme development for the converter input and output stages. A Lyapunov controller is embedded within the conventional output voltage sharing control loop. A master-slave control scheme is proposed to ensure power sharing under a range of operating conditions, and provides fault-tolerant operation since the status of 'master' can be reallocated in the event that the present 'master' module fails

State Policy Response to the Taxpayer Relief Act of 1997

The Taxpayer Relief Act of 1997 (TRA 1997) is the largest single increase in federal funding for higher education since the GI Bill. This chapter explores the impact of this new federal law on state higher education policy and offers options and recommendations for state response. These recommendations are based on the belief that programs which support both access and affordability are necessary to advance the larger national policy of college opportunity, but that affordability should not be allowed to supersede access as a policy goal

Modular input-parallel output-series DC/DC converter control with fault detection and redundancy

Large offshore wind farms require extensi ve sub-sea cables within the collection network. Present solutions are based aro und medium-voltage AC collection networks. Recent studies have highlighted the poten tial benefits of DC collection networks. However, achieving DC/DC conversion at th e required voltage and power levels presents a significant challenge for wind-tu rbine power electronics. This paper proposes an alternative DC collection network based around a modular DC/DC converter with input-parallel output-series (IPOS) connection. This modular topology can overcome the limitations imposed by semiconduct or voltage ratings and provides fault-tolerant operation. Small-signal analysis of the converter is presented to be used to facilitate controller design for the converter inpu t and output stages. A new master- slave control scheme and distributed voltage sharin g controllers are proposed that ensure power sharing under all operating conditions , including during failure of a master module. This control scheme achieves fault-t olerant operation by allowing the status of master module to be reallocated to any he althy module. The proposed control scheme is validated using simulation and experiment ation, considering active power sharing between modules with parameter mismatch

Longitudinal Analysis of Technical Debt for Strategic Platform Adoption

Increasingly, software producing organizations utilize a common software platform, joining an ecosystem; however, little expertise exists on selecting which platform to use when presented a number of different platforms. While technical debt can be used to examine the quality of a software platform by the organization that produces the software, a single discrete data point does not provide sufficient context for analysis. In this paper, we seek to resolve this difficulty by applying linear regression analysis to technical debt data collected by the SonarQube static analyzer. We apply this method to a case study on Cytoscape network analysis platform to perform a pedagogical investigation on the longitudinal technical debt found in that platform. We present our case study on the longitudinal technical debt in the form of arguments for and against the adoption of the Cytoscape network analysis platform, utilizing the data and analysis generated from our method

Omitted Variable Bias in the Link Between Planning and Performance

This article argues that existing research poorly specifies the link between planning and performance because of omitted variable bias. Researchers agree planning is a critical part of creating any new venture. Many researchers assess planning by whether a small firm has a written business plan. Unfortunately, efforts empirically to validate this relationship have been inconclusive. This article proposes that researchers should assess business plans both on the quality of the plan (and the planning process that produced it), and on the quality of the underlying business opportunity. Failure to account for both aspects of a business plan amounts to omitted variable bias, frustrating attempts to accurately estimate the true relationship