Showing papers on "Modular design published in 2009"

Control and Experiment of Pulsewidth-Modulated Modular Multilevel Converters

Abstract: A modular multilevel converter (MMC) is one of the next-generation multilevel converters intended for high- or medium-voltage power conversion without transformers. The MMC is based on cascade connection of multiple bidirectional chopper-cells per leg, thus requiring voltage-balancing control of the multiple floating DC capacitors. However, no paper has made an explicit discussion on voltage-balancing control with theoretical and experimental verifications. This paper deals with two types of pulsewidth-modulated modular multilevel converters (PWM- MMCs) with focus on their circuit configurations and voltage-balancing control. Combination of averaging and balancing controls enables the PWM-MMCs to achieve voltage balancing without any external circuit. The viability of the PWM-MMCs, as well as the effectiveness of the voltage-balancing control, is confirmed by simulation and experiment.

On dynamics and voltage control of the Modular Multilevel Converter

Abstract: This paper discusses the impact of modulation on stability issues of the Modular Multilevel Converter (M2C) The main idea is to describe the operation of this converter system mathematically, and suggest a control method that offers stable operation in the whole operation range A possible approach is to as­sume a continuous model, where all the modules in each arm are represented by variable voltage sources, and as a result, all pulse width modulation effects are disregarded After simulating this model and test­ing different control methods, useful conclusions on the operation of the M2C have been extracted The control methods are then implemented on a model with discrete half-bridge modules, in order to compare the results and to validate the continuous model approach When assuring that this model functions as expected, the goal of this paper is to conclude into a self-stabilizing voltage controller A controller is proposed, which eliminates circulating currents between the phase legs and balances the arm voltages regardless of the imposed alteranting current

Hierarchical modularity in human brain functional networks.

Abstract: The idea that complex systems have a hierarchical modular organization originates in the early 1960s and has recently attracted fresh support from quantitative studies of large scale, real-life networks. Here we investigate the hierarchical modular (or “modules-within-modules”) decomposition of human brain functional networks, measured using functional magnetic resonance imaging (fMRI) in 18 healthy volunteers under no-task or resting conditions. We used a customized template to extract networks with more than 1800 regional nodes, and we applied a fast algorithm to identify nested modular structure at several hierarchical levels. We used mutual information, 0 < I < 1, to estimate the similarity of community structure of networks in different subjects, and to identify the individual network that is most representative of the group. Results show that human brain functional networks have a hierarchical modular organization with a fair degree of similarity between subjects, I=0.63. The largest 5 modules at the highest level of the hierarchy were medial occipital, lateral occipital, central, parieto-frontal and fronto-temporal systems; occipital modules demonstrated less sub-modular organization than modules comprising regions of multimodal association cortex. Connector nodes and hubs, with a key role in inter-modular connectivity, were also concentrated in association cortical areas. We conclude that methods are available for hierarchical modular decomposition of large numbers of high resolution brain functional networks using computationally expedient algorithms. This could enable future investigations of Simon's original hypothesis that hierarchy or near-decomposability of physical symbol systems is a critical design feature for their fast adaptivity to changing environmental conditions.

Extensible component-based architecture for FLASH, a massively parallel, multiphysics simulation code

Abstract: FLASH is a publicly available high performance application code which has evolved into a modular, extensible software system from a collection of unconnected legacy codes. FLASH has been successful because its capabilities have been driven by the needs of scientific applications, without compromising maintainability, performance, and usability. In its newest incarnation, FLASH3 consists of inter-operable modules that can be combined to generate different applications. The FLASH architecture allows arbitrarily many alternative implementations of its components to co-exist and interchange with each other, resulting in greater flexibility. Further, a simple and elegant mechanism exists for customization of code functionality without the need to modify the core implementation of the source. A built-in unit test framework providing verifiability, combined with a rigorous software maintenance process, allow the code to operate simultaneously in the dual mode of production and development. In this paper we describe the FLASH3 architecture, with emphasis on solutions to the more challenging conflicts arising from solver complexity, portable performance requirements, and legacy codes. We also include results from user surveys conducted in 2005 and 2007, which highlight the success of the code.

A biomimetic modular polymer with tough and adaptive properties.

Abstract: Natural materials employ many elegant strategies to achieve mechanical properties required for survival under varying environmental conditions. Thus these remarkable biopolymers and nanocomposites often not only have a combination of mechanical properties such as high modulus, toughness, and elasticity, but also exhibit adaptive and stimuli-responsive properties. Inspired by skeletal muscle protein titin, we have synthesized a biomimetic modular polymer that not only closely mimics the modular multidomain structure of titin, but also manifests an exciting combination of mechanical properties, as well as adaptive properties such as self-healing and temperature-responsive shape-memory properties.

A new highly modular medium voltage converter topology for industrial drive applications

Abstract: This paper evaluates the features of a new highly modular multilevel converter topology (M2C) for medium voltage applications. Furthermore this paper will compare the M2C converter topology with existing converter topologies regarding the basic principle of operation, measurements as well as the harmonic content of the electrical output values.

Extensible Component Based Architecture for FLASH, A Massively Parallel, Multiphysics Simulation Code

Abstract: FLASH is a publicly available high performance application code which has evolved into a modular, extensible software system from a collection of unconnected legacy codes. FLASH has been successful because its capabilities have been driven by the needs of scientific applications, without compromising maintainability, performance, and usability. In its newest incarnation, FLASH3 consists of inter-operable modules that can be combined to generate different applications. The FLASH architecture allows arbitrarily many alternative implementations of its components to co-exist and interchange with each other, resulting in greater flexibility. Further, a simple and elegant mechanism exists for customization of code functionality without the need to modify the core implementation of the source. A built-in unit test framework providing verifiability, combined with a rigorous software maintenance process, allow the code to operate simultaneously in the dual mode of production and development. In this paper we describe the FLASH3 architecture, with emphasis on solutions to the more challenging conflicts arising from solver complexity, portable performance requirements, and legacy codes. We also include results from user surveys conducted in 2005 and 2007, which highlight the success of the code.

Modular Ontologies: Concepts, Theories and Techniques for Knowledge Modularization

Abstract: This book constitutes a collection of research achievements mature enough to provide a firm and reliable basis on modular ontologies. It gives the reader a detailed analysis of the state of the art of the research area and discusses the recent concepts, theories and techniques for knowledge modularization. The 13 papers presented in this book were all carefully reviewed before publication. They have been organized in three parts: Part I gives a general introduction to the idea and issues characterizing modularization and offers an in-depth analysis of properties, criteria and knowledge import techniques for modularization. Part II describes four major research proposals for creating modules from an existing ontology either by partitioning an ontology into a collection of modules or by extracting one or more modules from the ontology. Part III reports on collaborative approaches where modules that pre-exist are linked together through mappings to form a virtual large ontology.

TinkerCell: modular CAD tool for synthetic biology.

Abstract: Synthetic biology brings together concepts and techniques from engineering and biology. In this field, computer-aided design (CAD) is necessary in order to bridge the gap between computational modeling and biological data. Using a CAD application, it would be possible to construct models using available biological "parts" and directly generate the DNA sequence that represents the model, thus increasing the efficiency of design and construction of synthetic networks. An application named TinkerCell has been developed in order to serve as a CAD tool for synthetic biology. TinkerCell is a visual modeling tool that supports a hierarchy of biological parts. Each part in this hierarchy consists of a set of attributes that define the part, such as sequence or rate constants. Models that are constructed using these parts can be analyzed using various third-party C and Python programs that are hosted by TinkerCell via an extensive C and Python application programming interface (API). TinkerCell supports the notion of a module, which are networks with interfaces. Such modules can be connected to each other, forming larger modular networks. TinkerCell is a free and open-source project under the Berkeley Software Distribution license. Downloads, documentation, and tutorials are available at http://www.tinkercell.com . An ideal CAD application for engineering biological systems would provide features such as: building and simulating networks, analyzing robustness of networks, and searching databases for components that meet the design criteria. At the current state of synthetic biology, there are no established methods for measuring robustness or identifying components that fit a design. The same is true for databases of biological parts. TinkerCell's flexible modeling framework allows it to cope with changes in the field. Such changes may involve the way parts are characterized or the way synthetic networks are modeled and analyzed computationally. TinkerCell can readily accept third-party algorithms, allowing it to serve as a platform for testing different methods relevant to synthetic biology.

A family of 45nm IA processors

Abstract: Nehalem is a family of next-generation IA processors for mobile, desktop and server segments implemented in 45nm high-κ metal-gate CMOS [1]. The family features a new system architecture, significantly enhanced Core architecture [2], innovations in power management and modular design. The 4-core 8MB-L3-cache die has 731M transistors. We introduce a coherent point-to-point link called QuickPath Interconnect that is the foundation for coherent communication between IA processors, chipsets, I/O hubs and coprocessors/ accelerators for multiple generations. It features advanced power management, RAS capabilities and reduced hops/latency. At the physical level, it uses unidirectional variable-width differential signaling. The 45nm implementation features current-mode signaling with cascode driver, clock forwarding, source and sink termination, per-bit skew compensation and 2-tap driver equalization, as showin in Fig. 3.2.1. Signaling speed is up to 6.4GT/s in 45nm but the basic approach scales to 20GT/s using conventional copper interconnect [3].

Streams on wires: a query compiler for FPGAs

Abstract: Taking advantage of many-core, heterogeneous hardware for data processing tasks is a difficult problem. In this paper, we consider the use of FPGAs for data stream processing as coprocessors in many-core architectures. We present Glacier, a component library and compositional compiler that transforms continuous queries into logic circuits by composing library components on an operator-level basis. In the paper we consider selection, aggregation, grouping, as well as windowing operators, and discuss their design as modular elements.We also show how significant performance improvements can be achieved by inserting the FPGA into the system's data path (e.g., between the network interface and the host CPU). Our experiments show that queries on the FPGA can process streams at more than one million tuples per second and that they can do this directly from the network, removing much of the overhead of transferring the data to a conventional CPU.

Modular design for a fill-level-radar antenna system

Abstract: A modular system is for assembling a fill-level radar antenna, a fill-level radar antenna, and o a fill level radar. The modular system comprises several modules that can be interconnected. In this way a host of different fill-level radar antennae may be produced that are optimally adapted to the corresponding conditions.

A Modular Fuel Cell, Modular DC–DC Converter Concept for High Performance and Enhanced Reliability

Abstract: Fuel cell stacks produce a DC output with a 2:1 variation in output voltage from no-load to full-load. The output voltage of each fuel cell is about 0.4 V at full-load, and several of them are connected in series to construct a stack. An example 100 V fuel cell stack consists of 250 cells in series and to produce 300 V at full-load requires 750 cells stacked in series. Since fuel cells actively convert the supplied fuel to electricity, each cell requires proper distribution of fuel, humidification, coupled with water/thermal management needs. With this added complexity, stacking more cells in series decreases the reliability of the system. For example, in the presence of bad or malperforming cell/cells in a stack, uneven heating coupled with variations in cell voltages may occur. Continuous operation under these conditions may not be possible or the overall stack output power is severely limited. In this paper, a modular fuel cell powered by a modular DC-DC converter is proposed. The proposed concept electrically divides the fuel cell stack into various sections, each powered by a DC-DC converter. The proposed modular fuel cell powered by modular DC-DC converter eliminates many of these disadvantages, resulting in a fault tolerant system. A design example is presented for a 150-W, three-section fuel cell stack and DC-DC converter topology. Experimental results obtained on a 150-W, three-section proton exchange membrane (PEM) fuel cell stack powered by a modular DC-DC converter are discussed.

Integrality gaps for Sherali-Adams relaxations

Abstract: We prove strong lower bounds on integrality gaps of Sherali-Adams relaxations for MAX CUT, Vertex Cover, Sparsest Cut and other problems. Our constructions show gaps for Sherali-Adams relaxations that survive nδ rounds of lift and project. For MAX CUT and Vertex Cover, these show that even nδ rounds of Sherali-Adams do not yield a better than 2-e approximation. The main combinatorial challenge in constructing these gap examples is the construction of a fractional solution that is far from an integer solution, but yet admits consistent distributions of local solutions for all small subsets of variables. Satisfying this consistency requirement is one of the major hurdles to constructing Sherali-Adams gap examples. We present a modular recipe for achieving this, building on previous work on metrics with a local-global structure. We develop a conceptually simple geometric approach to constructing Sherali-Adams gap examples via constructions of consistent local SDP solutions. This geometric approach is surprisingly versatile. We construct Sherali-Adams gap examples for Unique Games based on our construction for MAX CUT together with a parallel repetition like procedure. This in turn allows us to obtain Sherali-Adams gap examples for any problem that has a Unique Games based hardness result (with some additional conditions on the reduction from Unique Games). Using this, we construct 2-e gap examples for Maximum Acyclic Subgraph that rules out any family of linear constraints with support at most nδ.

Has Click Chemistry Lead to a Paradigm Shift in Polymer Material Design

Abstract: Has the introduction of the click chemistry concept by Sharpless and colleagues in 2001 lead to a paradigm shift in how we approach the design of macromolecular materials; or is it simply a relatively inconsequential re-branding exercise of already existing and slightly optimized but well-tried and tested reactions as some critics would have it? The current Trend Article analyses the situation by examining a series of select macromolecular research fields to shed light on this question, providing an unambiguous answer: The focusing of polymer chemists through the click concept on what constitutes a powerful modular chemical transformation to generate a specific polymeric material is a defining element in contemporary synthetic polymer chemistry, transcending a specific reaction. Without the introduction of the click philosophy several classes of innovative materials and polymer designs would not have been realized.

A review of power electronics interfaces for distributed energy systems towards achieving low-cost modular design

Abstract: Due to increased attention towards clean and sustainable energy, distributed energy (DE) systems are gaining popularity all over the world. Power electronics are an integral part of these energy systems being able to convert generated electricity into consumer usable and utility compatible forms. But the addition of power electronics adds costs to the DE capital investments along with some reliability issues. Therefore, widespread use of distributed energy requires power electronics topologies that are less expensive and more dependable. Use of modular power electronics is a way to address these issues. Adoption of functional building blocks that can be used for multiple applications results in high volume production and reduced engineering effort, design testing, onsite installation and maintenance work for specific customer applications. In this paper, different power electronics topologies are reviewed that are typically used with distributed energy systems. The integrated power electronics module (IPEM) based back-to-back converter topologies are found to be most suitable interface that can operate with different DE systems with small or no modifications. Also the requirements for a hierarchical control structure with standardized power and communication interfaces are addressed in the paper along with some discussion on future design possibilities for the IPEM-based power electronics topologies. It is expected that modular and flexible power electronics and standardized controls and interfaces, will provide commonality in hardware and software for the power electronics interfaces, thus will enable their volume production and decrease their cost share in distributed energy applications.

Modularity concepts for the automotive industry: A critical review

Abstract: Modularization has been used mostly in order for the management of complex systems to be simplified. In the present paper, the major evolutions of modularity concepts are reviewed in the case of the automotive industry. The current trend indicates that the next generation of vehicles will change from the integrated “unibody” with high production volume and low flexibility, to the modular ones of middle to high production volume and flexibility. Typical examples of different modular design approaches are presented and discussed. The paper includes the vehicle's body design requirements that have to be met in order for such a modular approach to be effective.

Antimony: a modular model definition language

Abstract: Motivation: Model exchange in systems and synthetic biology has been standardized for computers with the Systems Biology Markup Language (SBML) and CellML, but specialized software is needed for the generation of models in these formats. Text-based model definition languages allow researchers to create models simply, and then export them to a common exchange format. Modular languages allow researchers to create and combine complex models more easily. We saw a use for a modular text-based language, together with a translation library to allow other programs to read the models as well. Summary: The Antimony language provides a way for a researcher to use simple text statements to create, import, and combine biological models, allowing complex models to be built from simpler models, and provides a special syntax for the creation of modular genetic networks. The libAntimony library allows other software packages to import these models and convert them either to SBML or their own internal format. Availability: The Antimony language specification and the libAntimony library are available under a BSD license from

Modular movement that is fully functional standalone and interchangeable in other portable devices

Abstract: A portable device comprising a modular movement is disclosed. The modular movement has a body housing a plurality of layers that include a top layer of glass, and a movement subassembly for displaying information, including time, wherein the modular movement includes all parts necessary for power and operation, including the displaying of the information, such that the modular movement is fully functional standalone. The portable device further includes a case, which includes a receptacle for removably receiving the modular movement without need for a tool, such that the modular movement is user-interchangeable with another case of another portable device.

Modular verification of dynamically adaptive systems

Abstract: Cyber-physical systems increasingly rely on dynamically adaptive programs to respond to changes in their physical environment; examples include ecosystem monitoring and disaster relief systems. These systems are considered high-assurance since errors during execution could result in injury, loss of life, environmental impact, and/or financial loss. In order to facilitate the development and verification of dynamically adaptive systems, we separate functional concerns from adaptive concerns. Specifically, we model a dynamically adaptive program as a collection of (non-adaptive) steady-state programs and a set of adaptations that realize transitions among steady state programs in response to environmental changes. We use Linear Temporal Logic (LTL) to specify properties of the non-adaptive portions of the system, and we use A-LTL (an adapt-operator extension toLTL) to concisely specify properties that hold during the adaptation process. Model checking offers an attractive approach to automatically analyzing models for adherence to formal properties and thus providing assurance. However, currently, model checkers are unable to verify properties specified using A-LTL. Moreover, as the number of steady-state programs and adaptations increase, the verification costs (in terms of space and time) potentially become unwieldy. To address these issues, we propose a modular model checking approach to verifying that a formal model of an adaptive program satisfies its requirements specified in LTL and A-LTL, respectively.

Modular stacked subsea power system architectures

Abstract: A sub-sea power delivery system (10) includes a plurality of modular power converter building blocks (12), (13) on each of the power source (20) side and the sub-sea load side (30) that are stacked and interconnected to meet site expansion requirements and electrical load topologies. The power delivery system comprises (10) a system DC transmission link/bus (14), wherein the system DC link (14) is configured to carry HVDC or MVDC power from an onshore utility or topside power source (20) to multiple sub-sea load modules (18). The stacked modular power converter topology on the sub-sea side of the sub-sea power delivery system (10) is symmetrical with the stacked modular power converter topology on the on-shore/top-side of the sub-sea power delivery system (10).

Modularity aspects of disjunctive stable models

Abstract: Practically all programming languages allow the programmer to split a program into several modules which brings along several advantages in software development In this paper, we are interested in the area of answer-set programming where fully declarative and nonmonotonic languages are applied In this context, obtaining a modular structure for programs is by no means straightforward since the output of an entire program cannot in general be composed from the output of its components To better understand the effects of disjunctive information on modularity we restrict the scope of analysis to the case of disjunctive logic programs (DLPs) subject to stable-model semantics We define the notion of a DLP-function, where a well-defined input/output interface is provided, and establish a novel module theorem which indicates the compositionality of stable-model semantics for DLP-functions The module theorem extends the well-known splitting-set theorem and enables the decomposition of DLP-functions given their strongly connected components based on positive dependencies induced by rules In this setting, it is also possible to split shared disjunctive rules among components using a generalized shifting technique The concept of modular equivalence is introduced for the mutual comparison of DLP-functions using a generalization of a translation-based verification method

Substrate and collector grid structures for integrated series connected photovoltaic arrays and process of manufacture of such arrays

Abstract: The invention teaches novel structure and methods for producing electrical current collectors and electrical interconnection structure. Such articles find particular use in facile production of modular arrays of photovoltaic cells. The current collector and interconnecting structures may be initially produced separately from the photovoltaic cells thereby allowing the use of unique materials and manufacture. Subsequent combination of the structures with photovoltaic cells allows facile and efficient completion of modular arrays. Methods for combining the collector and interconnection structures with cells and final interconnecting into modular arrays are taught.

Dynamic Rolling for a Modular Loop Robot

Abstract: Reconfigurable modular robots have the ability to use different gaits and configurations to perform various tasks. A rolling gait is the fastest currently implemented gait available for traversal over level ground and shows dramatic improvements in efficiency. In this work, we analyze and implement a sensor-based feedback controller to achieve dynamic rolling for a loop robot. The robot senses its position relative to the ground and changes its shape as it rolls. This shape is such that its center of gravity is maintained to be in front of its contact point with the ground, so in effect the robot is continuously falling and thus accelerates forward. Using simulation and experimental results, we show how the desired shape can be varied to achieve higher terminal velocities. The highest velocity achieved in this work is 26 module lengths per second (1.6 m/s) which is believed to be the fastest gait yet implemented for an untethered modular robot. One of the major findings is that more elongated shapes achieve higher terminal velocities than rounder shapes. We demonstrate that this trend holds going up inclines as well as down. We show that rounder shapes have lower specific resistance and are thus more energy efficient. The control scheme is scalable to an arbitrary number of modules, shown here using eight to 14 modules.

Complex modular structure of large-scale brain networks

Abstract: Modular structure is ubiquitous among real-world networks from related proteins to social groups. Here we analyze the modular organization of brain networks at a large scale (voxel level) extracted from functional magnetic resonance imaging signals. By using a random-walk-based method, we unveil the modularity of brain webs and show modules with a spatial distribution that matches anatomical structures with functional significance. The functional role of each node in the network is studied by analyzing its patterns of inter- and intramodular connections. Results suggest that the modular architecture constitutes the structural basis for the coexistence of functional integration of distant and specialized brain areas during normal brain activities at rest.

Real-time perception-guided motion planning for a personal robot

Abstract: This paper presents significant steps towards the online integration of 3D perception and manipulation for personal robotics applications. We propose a modular and distributed architecture, which seamlessly integrates the creation of 3D maps for collision detection and semantic annotations, with a real-time motion replanning framework. To validate our system, we present results obtained during a comprehensive mobile manipulation scenario, which includes the fusion of the above components with a higher level executive.