51 research outputs found
NUMA-CIC: Issues and Challenges for Scaling Scientific Applications on a Large Scale ccNuma Prototype
No full textThis whitepaper studies the various aspects and challenges of performance scaling on large scale shared memory systems.
Our experiments are performed on a large ccNUMA machine that consists of 72 IBM 3755 nodes connected with
NumaConnect and provides shared memory over a total of 1728 cores, a number that is far beyond conventional server
platforms. As benchmarks, three data-intensive and memory-bound applications with different communication patterns
are selected, namely Jacobi, CSR SpMV and Floyd-Warshall. Our results illustrate the need for numa-aware design and
implementation of shared-memory parallel algorithms in order to achieve scaling to high core counts. At the same time, we
observed that, depending on its communication pattern, an application could bene t more from explicit communication
using message passing
Asymptomatic Valvular Heart Disease: Indications and Timing for Surgery
No full textPatients who have severe aortic stenosis and remain asymptomatic is an issue of great interest and controversy. The reason of the argument is that on one side many physicians believe that irreversible myocardial damage and fibrosis may develop during a prolonged asymptomatic stage and therefore delayed aortic valve replacement will not have ideal results [1]. On the other side early surgery is associated with perioperative mortality and morbidity and significant long-term morbidity (2%/year) and mortality (1%/year), which combined together, exceed the possibility of sudden death (1%/year) from the aortic stenosis itself [2,3]. Therefore we should try to identify patients who may be at high risk of sudden death or patients who are ???pseudo-asymptomatic?? by limiting their gradual daily physical activity. Exercise stress test within a hospital environment is a useful tool to reveal these groups of patients.In brief, asymptomatic patients with severe aortic stenosis who have abnormal stress test or left ventricular systolic dysfunction or excessive left ventricular hypertrophy or very tight aortic stenosis, should be offered the benefit of aortic valve replacement
Master plan coastal havens, "Nikas", Kuwait
No full textCurrently there are 20,000 to 40,000 yachts in Kuwait. The majority of these yachts is stored on land because the number of berths in Kuwait is not sufficient to accommodate them all. Besides yachts, there are approximately 1,000 fishing vessels in Kuwait. The facilities for fishermen are not of sufficient quality. To overcome these problems, the Kuwaiti government initiated the development of a master plan for 9 coastal havens on Kuwait coast. Kuwait is located at the northeastern part of the Arabian Peninsula. It is bordering Saudi-Arabia and Iraq and lies on the northwestern shore of the Arabian Gulf. The emirate covers approximately 20,000 km2 and has a population 3.5 million inhabitants. The coastal havens need to facilitate fishing vessels, yachts, public transport vessels, vessels from the national authorities and incidentally vessels that take refuge in one of these coastal havens. Besides the possible locations of the havens, the demand and need for these facilities is an important aspect. The yachting demand potential gives an indication of the expected development in demand of the yachting industry up to the year 2030. There already is a need for berths in Kuwait at the moment. The master plan accounts for 6750 berths in the year 2030, an increase of 4750 berths in 25 years, and a small increase in the number of fishing vessels in Kuwait. The master plan contains recommendations for the proposed development directions and functions that have to be allocated for all coastal haven locations. The complexity of the concept of a coastal haven lays within the fact that it has to facilitate yachts, fishing vessels and somewhat larger vessels at the same time. The facility must be multipurpose to some extent, but other aspects must be kept separate in order to provide all users in their needs and meet their expectations. The design requirements and criteria are applied to one coastal haven location and are translated into three layout alternatives for one coastal haven location. The layouts are evaluated with two hydraulic models. These models simulate the wave propagation from an offshore data point into the wave conditions within the coastal haven basins. The modeled wave conditions are those that occur only once during the life of the coastal haven. The layout has to be such that it can protect the vessels from these conditions. During the modeling it is concluded that the layout needs to be such that the basins are relatively closed off. The acceptable wave height within the coastal haven is very limited, because damage to the yachts and speedboats used for fishing is not acceptable in a coastal haven.Hydraulic EngineeringCivil Engineering and Geoscience
The concept of doubt in the work of Atelie 66: critical analysis in the work of Dimitris and Suzana Antonakakis and their associates during the years 1960-80
No full textMCF Skew Estimation at the Receiver for ARoF Antenna Beamforming
No full textMulticore fibers can be used for Radio over Fiber transmission of mmwave signals for phased array antennas in 5G networks. The inter-core skew of these fibers distorts the radiation pattern and has to be measured and compensated. We propose a method to accurately measure the differential delays remotely, after installation, without intervening heavily with the transmitter setup. The properties of the phase response measured at a distant receiver are exploited to acquire the differential delays among the antenna array elements
Static Skew Compensation in Multi Core Radio over Fiber systems for 5G Mmwave Beamforming
No full textParametric and Optimization Study of Rectangular-Rounded, Hydraulic, Elastomeric, Reciprocating Seals at Temperatures between −54 and +135 °C
No full textHydraulic, reciprocating, polymeric seals are met in many engineering applications and are critical components for mechanism and machine reliability in industries including the automotive, marine, and aerospace industries. A parametric and optimization study of rectangular-rounded, hydraulic, reciprocating, elastomeric rod seals at −54, +23, and +135 °C is presented, which is particularly relevant to hydraulic actuators in aircraft landing gear. Parametric optimization not only improves performance, but also helps avoid sealing failures. The calculations were based on a physically based, deterministic mathematical model of such seals, experimentally validated at the aforementioned temperatures and recently published by the author. The parameters varied were the seal axial width and corner radius, seal elastic modulus, sealed pressure, stroking velocity, operating temperature, rod surface roughness, seal radial interference, and seal swelling by fluid uptake. Their influence was established based on the following performance variables: leakage rate, frictional force, coefficient of friction, temperature rise in the sealing contact, lambda ratio (proportional to the average film thickness in the contact), and ratio of the asperity friction force to the total friction force. The parametric study greatly facilitates the selection of optimal values of the analyzed parameters to minimize leakage, friction, and wear, either concurrently as a set or individually, depending on application priorities
Particle Entrapment in Line Elastohydrodynamic Contacts and the Influence of Intermolecular (van der Waals) Forces
No full textA metallic particle passing through concentrated rolling-sliding contacts is often linked to surface damage for particles larger than the available gap. At the instant of particle pinching, force balancing dictates particle entrapment and passing through the contact or rejection. It is vital to include all major forces in this process. This study revisits the analytical entrapment model previously published by the author for spherical micro-particles by incorporating a force so far overlooked in related studies, namely the van der Waals intermolecular force and, additionally, surface roughness effects. In conjunction with particle mechanical and fluid forces, this provides an almost complete set to use for correct force balancing. A parametric analysis shows the effect of several geometrical, mechanical, rheological, and surface parameters on spherical particle entrapment and reveals the significance of the van der Waals force for particles smaller than about 5–10 μm in diameter
Compact optical displacement sensing by detection of microwave signals generated from a monolithic passively mode-locked laser under feedback
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