Tallinn University of Technology

About: Tallinn University of Technology is a education organization based out in Tallinn, Estonia. It is known for research contribution in the topics: European union & Oil shale. The organization has 3688 authors who have published 10313 publications receiving 145058 citations. The organization is also known as: Tallinn Technical University & Tallinna Tehnikaülikool.

Carrier Level-Shifted Based Control Method for the PWM 3L-T-Type qZS Inverter With Capacitor Imbalance Compensation

Abstract: This paper presents a modified carrier level-shifted based control method for a pulsewidth modulation controlled three-phase three-level T-type quasi-impedance-source inverter. The benefits of the proposed strategy are a uniform distribution of shoot-through states of constant width throughout the fundamental period and the mitigation of the inner capacitors’ voltages imbalance. The latter is achieved by means of a proportional-integral controller, which adjusts the relative time application of redundant states. The improved performance is demonstrated in terms of reliability, as the capacitors do not suffer from neutral-point imbalance. The control method can also be implemented in a different multilevel inverter configuration with an impedance-source network. A comprehensive simulation study and several experiments were performed in order to validate the adopted method in situations of imbalanced capacitor voltages.

Solar Optiverter—A Novel Hybrid Approach to the Photovoltaic Module Level Power Electronics

Abstract: In this paper, the concept of an Optiverter is proposed as a novel class of photovoltaic (PV) module level power electronics systems Functionally, the Optiverter is a hybrid technology that combines the ultrawide maximum power point tracking (MPPT) voltage window of the PV power optimizers with the direct ac connectivity and inherent safety of the PV microinverters Thanks to the advanced multimode control with variable dc-link and the shade-tolerant MPPT algorithm, the proposed Optiverter ensures efficient energy harvest from the PV module in different shading scenarios To justify the superiority of the concept, the performance of a 300 W prototype of the PV Optiverter is experimentally compared to that of the industrial microinverters in different operation conditions, including an extreme case with opaque shading of two out of three substrings of the PV module

Soluble CD44 Interacts with Intermediate Filament Protein Vimentin on Endothelial Cell Surface

Abstract: CD44 is a cell surface glycoprotein that functions as hyaluronan receptor. Mouse and human serum contain substantial amounts of soluble CD44, generated either by shedding or alternative splicing. During inflammation and in cancer patients serum levels of soluble CD44 are significantly increased. Experimentally, soluble CD44 overexpression blocks cancer cell adhesion to HA. We have previously found that recombinant CD44 hyaluronan binding domain (CD44HABD) and its non-HA-binding mutant inhibited tumor xenograft growth, angiogenesis, and endothelial cell proliferation. These data suggested an additional target other than HA for CD44HABD. By using non-HA-binding CD44HABD Arg41Ala, Arg78Ser, and Tyr79Ser-triple mutant (CD443MUT) we have identified intermediate filament protein vimentin as a novel interaction partner of CD44. We found that vimentin is expressed on the cell surface of human umbilical vein endothelial cells (HUVEC). Endogenous CD44 and vimentin coprecipitate from HUVECs, and when overexpressed in vimentin-negative MCF-7 cells. By using deletion mutants, we found that CD44HABD and CD443MUT bind vimentin N-terminal head domain. CD443MUT binds vimentin in solution with a Kd in range of 12–37 nM, and immobilised vimentin with Kd of 74 nM. CD443MUT binds to HUVEC and recombinant vimentin displaces CD443MUT from its binding sites. CD44HABD and CD443MUT were internalized by wild-type endothelial cells, but not by lung endothelial cells isolated from vimentin knock-out mice. Together, these data suggest that vimentin provides a specific binding site for soluble CD44 on endothelial cells.

The Role of Private Actors in Public Sector Innovation

Abstract: The changing forms of governance stemming from the rise of New Public Management (NPM) and New Public Governance (NPG) have brought about significant changes in the relationship between the public and private sectors (Christensen and Laegreid 2007; Torfing and Triantafillou 2013). Not only have we witnessed a gradual increase in the involvement of private actors in the provision of public services, but we have also seen an upsurge of new forms of public–private interaction based on quasi-markets, partnerships and networks.This development, which has unfolded over the past four decades, entails two parallel but distinct trends. First, the gradual replacement of public with private solutions across a broad range of services, such as health, eldercare, employment services and childcare, many of which are services that have traditionally been seen as the family silver of the modern welfare state. While this trend has developed incrementally, it has nonetheless resulted in significant transfers of activities from the public to the private domain (Petersen and Hjelmar 2013). Second, we have witnessed the emergence of a growing number of innovation-oriented forms of public–private interaction under catchy titles such as ‘public–private partnerships’ (PPPs) (Hodge and Greve 2005), ‘public procurement of innovation’ (Lember, Kattel and Kalvet 2014), ‘innovative contracting out’ (Lindholst and Bogetoft 2011) and ‘public–private innovation partnerships’ (Brogaard and Petersen 2014). Today, perhaps more than ever before, there is a search for new forms of public–private collaboration that have the potential for delivering efficient public services, enhancing innovation and safeguarding public value in its widest sense (Moore 1995).This chapter examines how governments can enhance public sector innovation by utilizing new as well as old forms of public–private interaction that mobilizes the knowledge, competencies and resources of the private sector. We focus on three major yet distinct forms of public and private interplay: contracting out, public procurement and public–private partnerships (PPPs). The aim is to examine how these widely used interaction forms fit into the emerging NPG paradigm and how they can contribute to enhanced innovation, learning and collaboration under the evolving NPG framework.As outlined by the editors in Chapter 1 of the book, innovation and learning are embedded into collective action and institutions governing the public–private collaboration.