Streaming FFT on REDEFINE-v2: An Application-Architecture Design Space Exploration

In this paper we explore an implementation of a high-throughput, streaming application on REDEFINE-v2, which is an enhancement of REDEFINE. REDEFINE is a polymorphic ASIC combining the flexibility of a programmable solution with the execution speed of an ASIC. In REDEFINE Compute Elements are arranged in an 8x8 grid connected via a Network on Chip (NoC) called RECONNECT, to realize the various macrofunctional blocks of an equivalent ASIC. For a 1024-FFT we carry out an application-architecture design space exploration by examining the various characterizations of Compute Elements in terms of the size of the instruction store. We further study the impact by using application specific, vectorized FUs. By setting up different partitions of the FFT algorithm for persistent execution on REDEFINE-v2, we derive the benefits of setting up pipelined execution for higher performance. The impact of the REDEFINE-v2 micro-architecture for any arbitrary N-point FFT (N > 4096) FFT is also analyzed. We report the various algorithm-architecture tradeoffs in terms of area and execution speed with that of an ASIC implementation. In addition we compare the performance gain with respect to a GPP.

Analysis and design of split-capacitor resistive-inductive passive damping for LCL filters in grid-connected inverters

Grid-connected inverters require a third-order LCL filter to meet standards such as the IEEE Std. 519-1992 while being compact and cost-effective. LCL filter introduces resonance, which needs to be damped through active or passive methods. Passive damping schemes have less control complexity and are more reliable. This study explores the split-capacitor resistive-inductive (SC-RL) passive damping scheme. The SC-RL damped LCL filter is modelled using state space approach. Using this model, the power loss and damping are analysed. Based on the analysis, the SC-RL scheme is shown to have lower losses than other simpler passive damping methods. This makes the SC-RL scheme suitable for high power applications. A method for component selection that minimises the power loss in the damping resistors while keeping the system well damped is proposed. The design selection takes into account the influence of switching frequency, resonance frequency and the choice of inductance and capacitance values of the filter on the damping component selection. The use of normalised parameters makes it suitable for a wide range of design applications. Analytical results show the losses and quality factor to be in the range of 0.05-0.1% and 2.0-2.5, respectively, which are validated experimentally.

Medium-Voltage Drive for Induction Machine With Multilevel Dodecagonal Voltage Space Vectors With Symmetric Triangles

Multilevel inverters with dodecagonal (12-sided polygon) voltage space vector structure have advantages, such as complete elimination of fifth and seventh harmonics, reduction in electromagnetic interference, reduction in device voltage ratings, reduction of switching frequency, extension of linear modulation range, etc., making it a viable option for high-power medium-voltage drives. This paper proposes two power circuit topologies capable of generating multilevel dodecagonal voltage space vector structure with symmetric triangles (for the first time) with minimum number of dc-link power supplies and floating capacitor H-bridges. The first power topology is composed of two hybrid cascaded five-level inverters connected to either side of an open-end winding induction machine. Each inverter consists of a three-level neutral-point-clamped inverter, which is cascaded with an isolated H-bridge making it a five-level inverter. The second topology is for a normal induction motor. Both of these circuit topologies have inherent capacitor balancing for floating H-bridges for all modulation indexes, including transient operations. The proposed topologies do not require any precharging circuitry for startup. A simple pulsewidth modulation timing calculation method for space vector modulation is also presented in this paper. Due to the symmetric arrangement of congruent triangles within the voltage space vector structure, the timing computation requires only the sampled reference values and does not require any offline computation, lookup tables, or angle computation. Experimental results for steady-state operation and transient operation are also presented to validate the proposed concept.

Low-Order Harmonic Suppression for Open-End Winding IM With Dodecagonal Space Vector Using a Single DC-Link Supply

This paper proposes a technique to suppress low-order harmonics for an open-end winding induction motor drive for a full modulation range. One side of the machine is connected to a main inverter with a dc power supply, whereas the other inverter is connected to a capacitor from the other side. Harmonic suppression (with complete elimination of fifth- and seventh-order harmonics) is achieved by realizing dodecagonal space vectors using a combined pulsewidth modulation (PWM) control for the two inverters. The floating capacitor voltage is inherently controlled during the PWM operation. The proposed PWM technique is shown to be valid for the entire modulation range, including overmodulation and six-step mode of operation of the main inverter. Experimental results have been presented to validate the proposed technique.

Thermal test method for high power three-phase grid-connected inverters

Semiconductor device junction temperatures are maintained within datasheet specified limits to avoid failure in power converters. Burn-in tests are used to ensure this. In inverters, thermal time constants can be large and burn-in tests are required to be performed over long durations of time. At higher power levels, besides increased production cost, the testing requires sources and loads that can handle high power. In this study, a novel method to test a high power three-phase grid-connected inverter is proposed. The method eliminates the need for high power sources and loads. Only energy corresponding to the losses is consumed. The test is done by circulating rated current within the three legs of the inverter. All the phase legs being loaded, the method can be used to test the inverter in both cases of a common or independent cooling arrangement for the inverter phase legs. Further, the method can be used with different inverter configurations - three- or four-wire and for different pulse width modulation (PWM) techniques. The method has been experimentally validated on a 24 kVA inverter for a four-wire configuration that uses sine-triangle PWM and a three-wire configuration that uses conventional space vector PWM.

Paranormal operator on a Hilbert space

In this thesis an extensive study is made of the set P of all paranormal operators in B(H), the set of all bounded endomorphisms on the complex Hilbert space H. T ϵ B(H) is paranormal if for each z contained in the resolvent set of T, d(z, σ(T))//(T-zI)^-1 = 1 where d(z, σ(T)) is the distance from z to σ(T), the spectrum of T. P contains the set N of normal operators and P contains the set of hyponormal operators. However, P is contained in L, the set of all T ϵ B(H) such that the convex hull of the spectrum of T is equal to the closure of the numerical range of T. Thus, N≤P≤L.

If the uniform operator (norm) topology is placed on B(H), then the relative topological properties of N, P, L can be discussed. In Section IV, it is shown that: 1) N P and L are arc-wise connected and closed, 2) N, P, and L are nowhere dense subsets of B(H) when dim H ≥ 2, 3) N = P when dimH ˂ ∞ , 4) N is a nowhere dense subset of P when dimH ˂ ∞ , 5) P is not a nowhere dense subset of L when dimH ˂ ∞ , and 6) it is not known if P is a nowhere dense subset of L when dimH ˂ ∞.

The spectral properties of paranormal operators are of current interest in the literature. Putnam [22, 23] has shown that certain points on the boundary of the spectrum of a paranormal operator are either normal eigenvalues or normal approximate eigenvalues. Stampfli [26] has shown that a hyponormal operator with countable spectrum is normal. However, in Theorem 3.3, it is shown that a paranormal operator T with countable spectrum can be written as the direct sum, N ⊕ A, of a normal operator N with σ(N) = σ(T) and of an operator A with σ(A) a subset of the derived set of σ(T). It is then shown that A need not be normal. If we restrict the countable spectrum of T ϵ P to lie on a C²-smooth rectifiable Jordan curve G_o, then T must be normal [see Theorem 3.5 and its Corollary]. If T is a scalar paranormal operator with countable spectrum, then in order to conclude that T is normal the condition of σ(T) ≤ G_o can be relaxed [see Theorem 3.6]. In Theorem 3.7 it is then shown that the above result is not true when T is not assumed to be scalar. It was then conjectured that if T ϵ P with σ(T) ≤ G_o, then T is normal. The proof of Theorem 3.5 relies heavily on the assumption that T has countable spectrum and cannot be generalized. However, the corollary to Theorem 3.9 states that if T ϵ P with σ(T) ≤ G_o, then T has a non-trivial lattice of invariant subspaces. After the completion of most of the work on this thesis, Stampfli [30, 31] published a proof that a paranormal operator T with σ(T) ≤ G_o is normal. His proof uses some rather deep results concerning numerical ranges whereas the proof of Theorem 3.5 uses relatively elementary methods.

Development of a time and space resolved sampling probe diagnostic for engine exhaust hydrocarbons

In order to understand how unburned hydrocarbons emerge from SI engines and, in particular, how non-fuel hydrocarbons are formed and oxidized, a new gas sampling technique has been developed. A sampling unit, based on a combination of techniques used in the Fast Flame Ionization Detector (FFID) and wall-mounted sampling valves, was designed and built to capture a sample of exhaust gas during a specific period of the exhaust process and from a specific location within the exhaust port. The sampling unit consists of a transfer tube with one end in the exhaust port and the other connected to a three-way valve that leads, on one side, to a FFID and, on the other, to a vacuum chamber with a high-speed solenoid valve. Exhaust gas, drawn by the pressure drop into the vacuum chamber, impinges on the face of the solenoid valve and flows radially outward. Once per cycle during a specified crank angle interval, the solenoid valve opens and traps exhaust gas in a storage unit, from which gas chromatography (GC) measurements are made. The port end of the transfer tube can be moved to different locations longitudinally or radially, thus allowing spatial resolution and capturing any concentration differences between port walls and the center of the flow stream. Further, the solenoid valve's opening and closing times can be adjusted to allow sampling over a window as small as 0.6 ms during any portion of the cycle, allowing resolution of a crank angle interval as small as 15°CA. Cycle averaged total HC concentration measured by the FFID and that measured by the sampling unit are in good agreement, while the sampling unit goes one step further than the FFID by providing species concentrations. Comparison with previous measurements using wall-mounted sampling valves suggests that this sampling unit is fully capable of providing species concentration information as a function of air/fuel ratio, load, and engine speed at specific crank angles. © Copyright 1996 Society of Automotive Engineers, Inc.

Connected Life Courses:Influences on and Experiences of 'Midlife' In-Migration to Rural Areas

This paper aims to contribute to the theorisation of midlife migration into rural areas. Although the factors influencing migration are known to be variable at different stages of a person's life, much less well understood is how migration decisions at different stages of the life course are connected and how post-migration experiences may be influenced by an earlier life course stage. We argue that midlife migration decisions are the product of the migrant's lifetime experiences and influences up until that stage in their life alongside their expectations and aspirations for future life course stages. Using a case study of the Glens of Antrim (Northern Ireland), this paper specifically demonstrates the role of childhood memories to explain midlife migration to a rural area. In doing so, it argues that some findings more commonly associated with second-generation transnational migration are also equally relevant to migration within the UK. Roots migration and place attachment alongside the midlife migrant's post-migration sense of belonging and permanency are found to be influenced by the migrant's earlier memories, behaviours, and experiences.

Gender and Public Space in Divided Cities

The paper addresses two connected questions: firstly, in what ways might ‘public’ and ‘private’ spaces in cities be gendered; and secondly, what might this mean for the possibilities for complex forms of civility in a divided city such as Belfast? The specific focus on gendered dynamics of entitlement to inhabit urban space in this paper begins with some consideration of debates about the quality and experience of everyday life in cities, and the emergence of commonsense notions of ‘public’ and ‘private’ behaviour. Following this, key research concerned with the gendered dynamics of claimed collective, and particularly national, identities are outlined, in order to consider the significance of this literature for any study of the gender dynamics of life in a contested political context such as Belfast.

Marginal/minority popular music : the concept of the "third space" and the case for "hybridities" of cultures/identities /

The topic of this thesis is marginaVminority popular music and the question of identity; the term "marginaVminority" specifically refers to members of racial and cultural minorities who are socially and politically marginalized. The thesis argument is that popular music produced by members of cultural and racial minorities establishes cultural identity and resists racist discourse. Three marginaVminority popular music artists and their songs have been chosen for analysis in support of the argument: Gil Scott-Heron's "Gun," Tracy Chapman's "Fast Car" and Robbie Robertson's "Sacrifice." The thesis will draw from two fields of study; popular music and postcolonialism. Within the area of popular music, Theodor Adorno's "Standardization" theory is the focus. Within the area of postcolonialism, this thesis concentrates on two specific topics; 1) Stuart Hall's and Homi Bhabha's overlapping perspectives that identity is a process of cultural signification, and 2) Homi Bhabha's concept of the "Third Space." For Bhabha (1995a), the Third Space defines cultures in the moment of their use, at the moment of their exchange. The idea of identities arising out of cultural struggle suggests that identity is a process as opposed to a fixed center, an enclosed totality. Cultures arise from historical memory and memory has no center. Historical memory is de-centered and thus cultures are also de-centered, they are not enclosed totalities. This is what Bhabha means by "hybridity" of culture - that cultures are not unitary totalities, they are ways of knowing and speaking about a reality that is in constant flux. In this regard, the language of "Otherness" depends on suppressing or marginalizing the productive capacity of culture in the act of enunciation. The Third Space represents a strategy of enunciation that disrupts, interrupts and dislocates the dominant discursive construction of US and THEM, (a construction explained by Hall's concept of binary oppositions, detailed in Chapter 2). Bhabha uses the term "enunciation" as a linguistic metaphor for how cultural differences are articulated through discourse and thus how differences are discursively produced. Like Hall, Bhabha views culture as a process of understanding and of signification because Bhabha sees traditional cultures' struggle against colonizing cultures as transforming them. Adorno's theory of Standardization will be understood as a theoretical position of Western authority. The thesis will argue that Adorno's theory rests on the assumption that there is an "essence" to music, an essence that Adorno rationalizes as structure/form. The thesis will demonstrate that constructing music as possessing an essence is connected to ideology and power and in this regard, Adorno's Standardization theory is a discourse of White Western power. It will be argued that "essentialism" is at the root of Western "rationalization" of music, and that the definition of what constitutes music is an extension of Western racist "discourses" of the Other. The methodological framework of the thesis entails a) applying semiotics to each of the three songs examined and b) also applying Bhabha's model of the Third Space to each of the songs. In this thesis, semiotics specifically refers to Stuart Hall's retheorized semiotics, which recognizes the dual function of semiotics in the analysis of marginal racial/cultural identities, i.e., simultaneously represent embedded racial/cultural stereotypes, and the marginal raciaVcultural first person voice that disavows and thus reinscribes stereotyped identities. (Here, and throughout this thesis, "first person voice" is used not to denote the voice of the songwriter, but rather the collective voice of a marginal racial/cultural group). This dual function fits with Hall's and Bhabha's idea that cultural identity emerges out of cultural antagonism, cultural struggle. Bhabha's Third Space is also applied to each of the songs to show that cultural "struggle" between colonizers and colonized produces cultural hybridities, musically expressed as fusions of styles/sounds. The purpose of combining semiotics and postcolonialism in the three songs to be analyzed is to show that marginal popular music, produced by members of cultural and racial minorities, establishes cultural identity and resists racist discourse by overwriting identities of racial/cultural stereotypes with identities shaped by the first person voice enunciated in the Third Space, to produce identities of cultural hybridities. Semiotic codes of embedded "Black" and "Indian" stereotypes in each song's musical and lyrical text will be read and shown to be overwritten by the semiotic codes of the first person voice, which are decoded with the aid of postcolonial concepts such as "ambivalence," "hybridity" and "enunciation."

Particle swarm optimization for two-connected networks with bounded rings

The Two-Connected Network with Bounded Ring (2CNBR) problem is a network design problem addressing the connection of servers to create a survivable network with limited redirections in the event of failures. Particle Swarm Optimization (PSO) is a stochastic population-based optimization technique modeled on the social behaviour of flocking birds or schooling fish. This thesis applies PSO to the 2CNBR problem. As PSO is originally designed to handle a continuous solution space, modification of the algorithm was necessary in order to adapt it for such a highly constrained discrete combinatorial optimization problem. Presented are an indirect transcription scheme for applying PSO to such discrete optimization problems and an oscillating mechanism for averting stagnation.

Integrating control systems defined on the frame bundles of the space forms

This paper considers left-invariant control systems defined on the orthonormal frame bundles of simply connected manifolds of constant sectional curvature, namely the space forms Euclidean space E-3, the sphere S-3 and Hyperboloid H-3 with the corresponding frame bundles equal to the Euclidean group of motions SE(3), the rotation group SO(4) and the Lorentz group SO(1, 3). Orthonormal frame bundles of space forms coincide with their isometry groups and therefore the focus shifts to left-invariant control systems defined on Lie groups. In this paper a method for integrating these systems is given where the controls are time-independent. In the Euclidean case the elements of the Lie algebra se(3) are often referred to as twists. For constant twist motions, the corresponding curves g(t) is an element of SE(3) are known as screw motions, given in closed form by using the well known Rodrigues' formula. However, this formula is only applicable to the Euclidean case. This paper gives a method for computing the non-Euclidean screw motions in closed form. This involves decoupling the system into two lower dimensional systems using the double cover properties of Lie groups, then the lower dimensional systems are solved explicitly in closed form.

Aretusa: continuity, rupture, and space for intervention, 1944-1946

This article focuses on the cultural activity of Aretusa (1944-1946), a journal that was deeply connected to the inner circle of philosopher and politician Benedetto Croce (1866-1952). The article analyses the role played by periodical editors Francesco Flora (1891-1962) and Carlo Muscetta (1912-2004) in shaping the mission and direction of this journal. By drawing on Pierre Bourdieu’s theory of habitus, and the notion of hysteresis in particular, this study details the factors influencing the aesthetic dispositions, political positioning, and the wider impact of historical circumstances on the cultural practice of each editor while at the helm of the review.

An indecomposable Banach space of continuous functions which has small density

Using the method of forcing we construct a model for ZFC where CH does not hold and where there exists a connected compact topological space K of weight omega(1) < 2(omega) such that every operator on the Banach space of continuous functions on K is multiplication by a continuous function plus a weakly compact operator. In particular, the Banach space of continuous functions on K is indecomposable.

THE FUNDAMENTAL GROUP OF THE SPACE OF MAPS FROM A SURFACE INTO THE PROJECTIVE PLANE

In this work we compute the fundamental group of each connected component of the function space of maps from it closed surface into the projective space