Solve[order/topology == quasi-metric/x, x]

AbstractIn the study of the semantics of programming languages, the qualitative framework using partially ordered sets and the quantitative framework using pseudo-metric spaces have existed separately for years. Smyth however noticed that both concepts can be unified by means of quasi-metric spaces.Recent literature concerning these “quantitative domains”, lacks the canonicity which is so typical for the relationship between topological techniques and theoretical computer science in the classical settings mentioned above. On the one hand, this yields the use of structures which could be considered “ad hoc” from a categorical point of view, such as continuity spaces by Flagg and Kopperman. On the other hand, this yields “incomplete structures”, which essentially belong to one of both classical settings, such as the generalized Scott topology by Bonsangue e.a.We shall discuss a natural generalization of the symbiosis between ordered sets and topology to an analogous relationship between quasi-metric spaces and approach spaces. Approach spaces seem to be an important tool in the study of certain aspects concerning quantitative domains

Driving electronics for OLED lighting

This paper proposes the concept of integrating an OLED (foil) and its driving electronics into one module. A complete light system consisting of these modules is the ultimate goal of this work. The main focus in this article is on the design of the driver chip and the circuit implementation. The measurement results confirm that it is possible to control the light output of the different modules

Hybrid monolithic integration of high-power DC-DC converters in a high-voltage technology

The supply of electrical energy to home, commercial, and industrial users has become ubiquitous, and it is hard to imagine a world without the facilities provided by electrical energy. Despite the ever increasing efficiency of nearly every electrical application, the worldwide demand for electrical power continues to increase, since the number of users and applications more than compensates for these technological improvements. In order to maintain the affordability and feasibility of the total production, it is essential for the distribution of the produced electrical energy to be as efficient as possible. In other words the loss in the power distribution is to be minimized. By transporting electrical energy at the maximum safe voltage, the current in the conductors, and the associated conduction loss can remain as low as possible. In order to optimize the total efficiency, the high transportation voltage needs to be converted to the appropriate lower voltage as close as possible to the end user. Obviously, this conversion also needs to be as efficient, affordable, and compact as possible. Because of the ever increasing integration of electronic systems, where more and more functionality is combined in monolithically integrated circuits, the cost, the power consumption, and the size of these electronic systems can be greatly reduced. This thorough integration is not limited to the electronic systems that are the end users of the electrical energy, but can also be applied to the power conversion itself. In most modern applications, the voltage conversion is implemented as a switching DC-DC converter, in which electrical energy is temporarily stored in reactive elements, i.e. inductors or capacitors. High switching speeds are used to allow for a compact and efficient implementation. For low power levels, typically below 1 Watt, it is possible to monolithically implement the voltage conversion on an integrated circuit. In some cases, this is even done on the same integrated circuit that is the end user of the electrical energy to minimize the system dimensions. For higher power levels, it is no longer feasible to achieve the desired efficiency with monolithically integrated components, and some external components prove indispensable. Usually, the reactive components are the main limiting factor, and are the first components to be moved away from the integrated circuit for increasing power levels. The semiconductor components, including the power transistors, remain part of the integrated circuit. Using this hybrid approach, it is possible in modern converterapplications to process around 60 Watt, albeit limited to voltages of a few Volt. For hybrid integrated converters with an output voltage of tens of Volt, the power is limited to approximately 10 Watt. For even higher power levels, the integrated power transistors also become a limiting factor, and are replaced with discrete power devices. In these discrete converters, greatly increased power levels become possible, although the system size rapidly increases. In this work, the limits of the hybrid approach are explored when using so-called smart-power technologies. Smart-power technologies are standard lowcost submicron CMOS technologies that are complemented with a number of integrated high-voltage devices. By using an appropriate combination of smart-power technologies and circuit topologies, it is possible to improve on the current state-of-the-art converters, by optimizing the size, the cost, and the efficiency. To determine the limits of smart-power DC-DC converters, we first discuss the major contributing factors for an efficient energy distribution, and take a look at the role of voltage conversion in the energy distribution. Considering the limitations of the technologies and the potential application areas, we define two test-cases in the telecommunications sector for which we want to optimize the hybrid monolithic integration in a smart-power technology. Subsequently, we explore the specifications of an ideal converter, and the relevant properties of the affordable smart-power technologies for the implementation of DC-DC converters. Taking into account the limitations of these technologies, we define a cost function that allows to systematically evaluate the different potential converter topologies, without having to perform a full design cycle for each topology. From this cost function, we notice that the de facto default topology selection in discrete converters, which is typically based on output power, is not optimal for converters with integrated power transistors. Based on the cost function and the boundary conditions of our test-cases, we determine the optimal topology for a smart-power implementation of these applications. Then, we take another step towards the real world and evaluate the influence of parasitic elements in a smart-power implementation of switching converters. It is noticed that the voltage overshoot caused by the transformer secondary side leakage inductance is a major roadblock for an efficient implementation. Since the usual approach to this voltage overshoot in discrete converters is not applicable in smart-power converters due to technological limitations, an alternative approach is shown and implemented. The energy from the voltage overshoot is absorbed and transferred to the output of the converter. This allows for a significant reduction in the voltage overshoot, while maintaining a high efficiency, leading to an efficient, compact, and low-cost implementation. The effectiveness of this approach was tested and demonstrated in both a version using a commercially available integrated circuit, and our own implementation in a smart-power integrated circuit. Finally, we also take a look at the optimization of switching converters over the load range by exploiting the capabilities of highly integrated converters. Although the maximum output power remains one of the defining characteristics of converters, it has been shown that most converters spend a majority of their lifetime delivering significantly lower output power. Therefore, it is also desirable to optimize the efficiency of the converter at reduced output current and output power. By splitting the power transistors in multiple independent segments, which are turned on or off in function of the current, the efficiency at low currents can be significantly improved, without introducing undesirable frequency components in the output voltage, and without harming the efficiency at higher currents. These properties allow a near universal application of the optimization technique in hybrid monolithic DC-DC converter applications, without significant impact on the complexity and the cost of the system. This approach for the optimization of switching converters over the load range was demonstrated using a boost converter with discrete power transistors. The demonstration of our smart-power implementation was limited to simulations due to an issue with a digital control block. On a finishing note, we formulate the general conclusions and provide an outlook on potential future work based on this research

Quantifying completion

Approach uniformities were introduced in Lowen and Windels (1998) as the canonical generalization of both metric spaces and uniform spaces. This text presents in this new context of quantitative uniform spaces, a reflective completion theory which generalizes the well-known completions of metric and uniform spaces. This completion behaves nicely with respect to initial structures and hyperspaces. Also, continuous extensions of pseudo-metrics on uniform spaces and (real) compactification of approach spaces can be interpreted in terms of this completion

Graphlet-adjacencies provide complementary views on the functional organisation of the cell and cancer mechanisms

Recent biotechnological advances have led to a wealth of biological network data. Topo- logical analysis of these networks (i.e., the analysis of their structure) has led to break- throughs in biology and medicine. The state-of-the-art topological node and network descriptors are based on graphlets, induced connected subgraphs of different shapes (e.g., paths, triangles). However, current graphlet-based methods ignore neighbourhood infor- mation (i.e., what nodes are connected). Therefore, to capture topology and connectivity information simultaneously, I introduce graphlet adjacency, which considers two nodes adjacent based on their frequency of co-occurrence on a given graphlet. I use graphlet adjacency to generalise spectral methods and apply these on molecular networks. I show that, depending on the chosen graphlet, graphlet spectral clustering uncovers clusters en- riched in different biological functions, and graphlet diffusion of gene mutation scores predicts different sets of cancer driver genes. This demonstrates that graphlet adjacency captures topology-function and topology-disease relationships in molecular networks. To further detail these relationships, I take a pathway-focused approach. To enable this investigation, I introduce graphlet eigencentrality to compute the importance of a gene in a pathway either from the local pathway perspective or from the global network perspective. I show that pathways are best described by the graphlet adjacencies that capture the importance of their functionally critical genes. I also show that cancer driver genes characteristically perform hub roles between pathways. Given the latter finding, I hypothesise that cancer pathways should be identified by changes in their pathway-pathway relationships. Within this context, I propose pathway- driven non-negative matrix tri-factorisation (PNMTF), which fuses molecular network data and pathway annotations to learn an embedding space that captures the organisation of a network as a composition of subnetworks. In this space, I measure the functional importance of a pathway or gene in the cell and its functional disruption in cancer. I apply this method to predict genes and the pathways involved in four major cancers. By using graphlet-adjacency, I can exploit the tendency of cancer-related genes to perform hub roles to improve the prediction accuracy

Active asynchronous secondary side voltage clamping

An asynchronous active voltage clamp for the secondary side of switching DC-DC converters is proposed. The control of the proposed clamping circuit is independent from the main converter, thus allowing use of a physically small inductor and offering increased control over the clamping operation. Measurements on a 1 MHz implementation of the asynchronous active voltage clamp on the secondary side of a prototype 220 kHz phase shifted full bridge DC-DC converter confirm the effectiveness of the voltage clamping and the improved converter efficiency

GABA, not glutamate, controls the activity of substantia nigra reticulata neurons in awake, unrestrained rats

Substantia nigra pars reticulata (SNr) receives both GABAergic and glutamatergic (GLU) inputs that are believed to act together to regulate neuronal activity in this structure. To examine the role of these inputs, single-unit recording was coupled with iontophoresis of GLU and GABA in rats under two conditions: awake, unrestrained and under chloral hydrate anesthesia. Although GABA potently inhibited SNr cells in both conditions, freely moving rats showed lower sensitivity than anesthetized animals. Likewise, GLU effectively induced excitations in most SNr neurons in anesthetized animals but was much less effective in awake, unrestrained animals in terms of both the number of sensitive cells and the magnitude of GLU-induced excitation. These findings, along with consistent excitations induced by bicuculline in awake, unrestrained rats, suggest that modulation of GABA inhibitory input, not the opposing actions of GLU and GABA, is the primary factor that regulates the activity state of SNr neurons

Numerical simulation of a multi-inlet microfluidic device for biosensing purposes in osteoporosis management

Objectives In this paper, the effect of the position of the inlet and outlet microchannels on the flow profile and the geometry of the recognition chamber for sample pre-treatment in an electrochemical biosensor to be used in osteoporosis management were investigated. Methods All numerical computation presented in this work were performed using COMSOL Multiphysics and Fluent. Simulation was performed for a three-dimensional, incompressible Navier-Stokes flow and so explicit biphasic volume of fluid (VOF) equations were used. Results In the designed microfluidic system, a pressure-driven laminar flow with no-slip boundary condition was responsible for fluid actuation through microchannels in a reproducible approach. Based on the simulation results, the number of outlets was increased and the angel through which the inlets and outlets were attached to the microchamber was changed so that the dead volume would be eliminated and the fluid flow trajectory, the velocity field and pressure were evenly distributed across the chamber. The Re number in the inlets was equal to 4.41, suggesting a laminar flow at this site. Conclusion The simulation results along with the fact that the design change was tested using laser ablated tape and a color dye at different steps provided the researchers with the opportunity to study the changes in a fast and accurate but cheap method. The absence of backflow helps with the cross-talk concern in the channels and the lack of bubbles and complete coverage of the chamber helps with a better surface modification and thus better sensing performance

Traceability Management Architectures Supporting Total Traceability in the Context of Software Engineering

In the area of Software Engineering, traceability is defined as the capability to track requirements, their evolution and transformation in different components related to engineering process, as well as the management of the relationships between those components. However the current state of the art in traceability does not keep in mind many of the elements that compose a product, specially those created before requirements arise, nor the appropriated use of traceability to manage the knowledge underlying in order to be handled by other organizational or engineering processes. In this work we describe the architecture of a reference model that establishes a set of definitions, processes and models which allow a proper management of traceability and further uses of it, in a wider context than the one related to software development