HIGH SPEED CMOS/SOS IMPLEMENTATION OF A BIT LEVEL SYSTOLIC CORRELATOR.

The fabrication and performance of the first bit-level systolic correlator array is described. The application of systolic array concepts at the bit level provides a simple and extremely powerful method for implementing high-performance digital processing functions. The resulting structure is highly regular, facilitating yield enhancement through fault-tolerant redundancy techniques and therefore ideally suited to implementation as a VLSI chip. The CMOS/SOS chip operates at 35 MHz, is fully cascadable and exhibits 64-stage correlation for 1-bit reference and 4-bit data. 7 refs.

Analysis of Two-Speed Wind Farm Operation From Grid-Side Measurements

This paper analyzes data captured by a phasor measurement unit at a wind farm, employing two-speed induction generators, and investigates aspects of the control system's interaction with the power system. Composite superimposed transient events are proposed as a method to improve the quality of the analysis and reduce errors caused by unknowns, such as wind speed variation. A Mathworks SimPowerSystems model validates the inertia contribution of the wind farm, which is an important parameter in power systems with high wind penetration. Transients caused by turbine speed transitions are identified and explained. The analysis also highlights areas where wind farm control should be improved if useful inertia contribution is to be provided.

Senegalin: a novel antimicrobial/myotropic hexadecapeptide from the skin secretion of the African running frog, Kassina senegalensis

Amphibian skin is a rich and unique source of novel bioactive peptides most of which are endowed with either antimicrobial or pharmacological properties. Here we report the identification and structural characterization of a novel peptide, named senegalin, which possesses both activities. Senegalin is a hexadecapeptide amide (FLPFLIPALTSLISSL-NH2) of unique primary structure found in the skin secretion of the African running frog, Kassina senegalensis. The structure of the biosynthetic precursor of senegalin, deduced from cloned skin cDNA, consists of 76 amino acid residues and displays the typical domain organization of an amphibian skin peptide precursor. Both natural senegalin and its synthetic replicate
displayed antimicrobial and myotropic activities. Senegalin was active against Staphylococcus aureus (MIC 50µM) and Candida albicans (MIC 150µM) but was nonhaemolytic at concentrations up to and including 150µM. In contrast, senegalin induced a dose-dependent contraction of rat urinary bladder smooth muscle (EC50 2.9nM) and a dosedependent relaxation of rat tail artery smooth muscle (EC50 37.7nM). Senegalin thus represents a prototype biologically-active amphibian skin peptide and illustrates the fact thatamphibian skin secretion peptidomes continue to be unique sources of such molecules.

Tip leakage flow and heat transfer on turbine blade tip and casing, Part 1: Effect of tip clearance height and rotation speed

Steady simulations were performed to investigate tip leakage flow and heat transfer characteristics on the rotor blade tip and casing in a single-stage gas turbine engine. A typical high-pressure gas turbine stage was modeled with a pressure ratio of 3.2. The predicted isentropic Mach number and adiabatic wall temperature on the casing showed good agreement with available experimental data under similar operating condition. The present numerical study focuses extensively on the effects of tip clearance heights and rotor rotational speeds on the blade tip and casing heat transfer characteristics. It was observed that the tip leakage flow structure is highly dependent on the height of the tip gap and the speed of the rotor. In all cases, the tip leakage flow was seen to separate and recirculate just around the corner of the pressure side of the blade tip. This region of re-circulating flow enlarges with increasing clearance heights. The separated leakage flow reattaches afterwards on the tip surface. Leakage flow reattachment was shown to enhance surface heat transfer at the tip. The interaction between tip leakage flow and secondary flows that is induced by the relative casing motion is found to significantly influence the blade tip and casing heat transfer distribution. A region of critical heat transfer exists on the casing near the blade tip leading edge and along the pressure-side edge for all the clearance heights that were investigated. At high rotation speed, the region of critical heat transfer tends to move towards the trailing edge due to the change in inflow angle.

Novel Radio Link Buffer Management Schemes for End-User Multi-class Traffic in High Speed Packet Access Networks

The requirement to provide multimedia services with QoS support in mobile networks has led to standardization and deployment of high speed data access technologies such as the High Speed Downlink Packet Access (HSDPA) system. HSDPA improves downlink packet data and multimedia services support in WCDMA-based cellular networks. As is the trend in emerging wireless access technologies, HSDPA supports end-user multi-class sessions comprising parallel flows with diverse Quality of Service (QoS) requirements, such as real-time (RT) voice or video streaming concurrent with non real-time (NRT) data service being transmitted to the same user, with differentiated queuing at the radio link interface. Hence, in this paper we present and evaluate novel radio link buffer management schemes for QoS control of multimedia traffic comprising concurrent RT and NRT flows in the same HSDPA end-user session. The new buffer management schemes—Enhanced Time Space Priority (E-TSP) and Dynamic Time Space Priority (D-TSP)—are designed to improve radio link and network resource utilization as well as optimize end-to-end QoS performance of both RT and NRT flows in the end-user session. Both schemes are based on a Time-Space Priority (TSP) queuing system, which provides joint delay and loss differentiation between the flows by queuing (partially) loss tolerant RT flow packets for higher transmission priority but with restricted access to the buffer space, whilst allowing unlimited access to the buffer space for delay-tolerant NRT flow but with queuing for lower transmission priority. Experiments by means of extensive system-level HSDPA simulations demonstrates that with the proposed TSP-based radio link buffer management schemes, significant end-to-end QoS performance gains accrue to end-user traffic with simultaneous RT and NRT flows, in addition to improved resource utilization in the radio access network.

Analysis of Fixed-Speed Wind Farm Low-Frequency Power Pulsations using a Wavelet-Prony Method

The increasing penetration of wind generation on the Island of Ireland has been accompanied by close investigation of low-frequency periodic pulsations contained within the active power flow from different wind farms. A primary concern is excitation of existing low-frequency oscillation modes already present on the system, particularly the 0.75 Hz mode as a consequence of the interconnected Northern and Southern power system networks. Recently grid code requirements on the Northern Ireland power system have been updated stipulating that wind farms connected after 2005 must be able to control the magnitude of oscillations in the range of 0.25 - 1.75 Hz to within 1% of the wind farm's registered output. In order to determine whether wind farm low-frequency oscillations have a negative effect (excite other modes) or possibly a positive impact (damping of existing modes) on the power system, the oscillations at the point of connection must be measured and characterised. Using time - frequency methods, research presented in this paper has been conducted to extract signal features from measured low-frequency active power pulsations produced by wind farms to determine the effective composition of possible oscillatory modes which may have a detrimental effect on system dynamic stability. The paper proposes a combined wavelet-Prony method to extract modal components and determine damping factors. The method is exemplified using real data obtained from wind farm measurements.

A Study of Tower Shadow Effect on Fixed-Speed Wind Turbines

This paper studies the impact of tower shadow effect on the power output of a fixed-speed wind farm. A data acquisition unit was placed at a wind farm in Northern Ireland which consists of ten fixed-speed wind turbines. The recording equipment logged the wind farmpsilas electrical data, which was time stamped using the global positioning network. Video footage of the wind farm was recorded and from it the blade angle of each turbine was determined with respect to time. Using the blade angle data and the wind farmpsilas power output, studies where performed to ascertain the extent of tower shadow effect on power fluctuation. This paper presents evidence that suggests that tower shadow effect has a significant impact on power fluctuation and that this effect is increased due to the synchronising of turbine blades around the tower region.

Modelling and Control of a Variable-Speed Switched Reluctance Generator based Wind Turbine

This paper studies the system modelling and control aspects of switched reluctance generator (SRG) based variable speed wind turbines. A control system is implemented to provide proper operation of the SRG as well as power tracking capabilities for varying wind speeds. The control system for the grid side inverter that will allow the SRG to properly generate power to the system is also presented. Studies are presented of both the SRG and inverter control systems capabilities during a balanced three-phase fault. The paper will demonstrate that the SRG based wind turbine presents a feasible variable wind speed solution with good fault response capabilities.

Effect of impeller speed on mechanical and dissolution properties of high-shear granules

Impeller speed is one of the most crucial process variables that affect the properties of the granules produced in a high-shear granulator. Several reports can be found in literature that discuss the influence of impeller speed on the granules size. For instance some researchers like Knight report an increase of granule size with impeller speed [1] and [2], while others (Scheaefer et al. and Ramaker et al.) observed a decrease of granules size with increasing impeller speed [3] and [4]. However there is limited work reported in literature on the effect of the impeller speed on the mechanical properties of granules. Mechanical properties are important as they affect the performance of the granules on the other downstream process such as transportation and handling. The work reported here serves to address the missing in knowledge gap regarding the influence of impeller speed on mechanical properties granules. How the granulation system responds to the changes in the impeller speeds depends on binder that is used in the process. For this reason the two extreme cases, of a low viscosity binder system and high viscosity binder system are considered in this research. For low viscosity binder system it was observed that the granule size decreased with increasing impeller speed whilst for the high viscosity binder system the opposite was observed by Knight [1]. The granule strength, the Young's modulus and yield strength of the high viscosity granules increased with increasing impeller speed where as the opposite trends were observed for the low viscosity binder granules.

K-Contagion: Sound, Space and Speed in Psy's 'Gangnam Style'

Park Jae-Sang’s (otherwise known as PSY) bewilderingly successful pop contagion ‘Gangnam Style’ needs no introduction. As of January 2013, it has become the most watched video in YouTube’s history and has garnered over 1.23 billion hits since. ‘Gangnam Style’ has also become a rapid global pop phenomenon with multiple parodic reproductions, imitations and adaptations; Rapper PSY himself has become an international name and styled as the ‘anti-hero’ of the glamour-driven K-pop scene. His fame has transcended the social sphere and permeated the political stratosphere with politicians such as Barrack Obama and David Cameron being among the many whom PSY has exchanged pleasantries with. Apart from breaking ground and creating social and media history in many ways, ‘Gangnam Style’ has even been purported by UN Secretary-General Ban Ki Moon to be a “force for world peace” – cultural barriers are demolished as the world dances. Underlying this sentiment is the video’s almost universal appeal that assumes a supracultural yet equally paradoxical translatability: Korea’s neoteric ‘K-Wave’ phenomenon is at once local yet global, and where the latter is predicated on the former quality. The paper’s concern is thus two-fold. It will consider the dromological aspects of this musical contagion as it exemplifies and performs quite literally Paul Virilio’s thesis that the modern condition is driven by speed yet arrested to a dictatorship of movement. While many theories have been put forward for this astounding pop peculiarity, this paper would also examine the intercultural currents that advocate such a global (pop) cultural response. Through an analysis of sonic qualities – digital techno-beat rhythms, synth-based musicality, cyclical lyrics, horse-galloping movements – and acoustic receptions, it will consider the simultaneous and dichotomous currents of glocalisation and globalisation as it relates to the ways in which sonic ‘hyper-links’ establish new concepts of global-cultural identities even as these seem to be interrogated in the borderless worlds of hyper-mediatised realities and cultural technologies.