853 research outputs found
On Characterizing the Data Movement Complexity of Computational DAGs for Parallel Execution
Technology trends are making the cost of data movement increasingly dominant,
both in terms of energy and time, over the cost of performing arithmetic
operations in computer systems. The fundamental ratio of aggregate data
movement bandwidth to the total computational power (also referred to the
machine balance parameter) in parallel computer systems is decreasing. It is
there- fore of considerable importance to characterize the inherent data
movement requirements of parallel algorithms, so that the minimal architectural
balance parameters required to support it on future systems can be well
understood. In this paper, we develop an extension of the well-known red-blue
pebble game to develop lower bounds on the data movement complexity for the
parallel execution of computational directed acyclic graphs (CDAGs) on parallel
systems. We model multi-node multi-core parallel systems, with the total
physical memory distributed across the nodes (that are connected through some
interconnection network) and in a multi-level shared cache hierarchy for
processors within a node. We also develop new techniques for lower bound
characterization of non-homogeneous CDAGs. We demonstrate the use of the
methodology by analyzing the CDAGs of several numerical algorithms, to develop
lower bounds on data movement for their parallel execution
Sequence variation in the haemagglutinin-neuraminidase gene of human parainfluenza virus type 3 isolates in the UK
The sequence variation in a 934 base-pair region of the gene encoding the haemagglutinin-neuraminidase of five human parainfluenza virus type 3 (HPIV3) isolates was determined together with that of a prototype UK strain. All of the clinical isolates were from the Manchester area of the UK and were obtained in 1990. 1991 and 1993. The gene segment was amplified by the polymerase chain reaction using HPIVB-specific oligonucleotide primers. The nucleotide homology of the strains was high, around 99% and specific differences in the UK sequences when compared with that of the US prototype strain were identified. In addition, a number of isolate-specific differences were seen. No correlation was detected between the observed nucleotide mutations and the year of isolation, which supports the hypothesis that HPIV3 shows cocirculation of a heterogeneous population of viruses rather than varying with time in a linear fashion. However, the data suggested that geographically-defined genetic lineages of HPIV3 may exist
On Characterizing the Data Access Complexity of Programs
Technology trends will cause data movement to account for the majority of
energy expenditure and execution time on emerging computers. Therefore,
computational complexity will no longer be a sufficient metric for comparing
algorithms, and a fundamental characterization of data access complexity will
be increasingly important. The problem of developing lower bounds for data
access complexity has been modeled using the formalism of Hong & Kung's
red/blue pebble game for computational directed acyclic graphs (CDAGs).
However, previously developed approaches to lower bounds analysis for the
red/blue pebble game are very limited in effectiveness when applied to CDAGs of
real programs, with computations comprised of multiple sub-computations with
differing DAG structure. We address this problem by developing an approach for
effectively composing lower bounds based on graph decomposition. We also
develop a static analysis algorithm to derive the asymptotic data-access lower
bounds of programs, as a function of the problem size and cache size
Identification of the Factors Affecting the Academic Performance of the Science Undergraduates of the Eastern University, Sri Lanka: A Case Study
Academic performance of Undergraduates in Sri Lankan Universities becomes an important factor among the academics and educators because the employability of the Sri Lankan graduate is growing as a challenge these days. Therefore, there is a need to identify and address the factors affecting the academic performance of Undergraduates in Sri Lankan universities. A survey designed was employed with questionnaires administered to the third year undergraduates of the Faculty of Science, Eastern University, Sri Lanka. The questionnaire covered the socio-economic factors, academic performances of the General Certificate of Education (GCE) Examinations in schools, extra studies of computer courses and English, extra-curricular activities and family backgrounds. The Grade Point Average for the first and second year of studies was used as the responses for the academic performance. The study revealed that gender, mother language, academic grades obtained for English language and general English at the GCE examinations, the stream of study of the degree programme in the University, the number of attempt at the GCE examination to enter the university were the mostly influencing factors. This study therefore recommended giving priority for learning mother language and improving English language and general English in GCE examinations in order to improve the academic performance of the students in the Faculty of Science, Eastern University, Sri Lanka. Keywords: Academic Performance, Undergraduates, GPA, Gender, Proficiency in English. DOI: 10.7176/JEP/11-15-17 Publication date:May 31st 202
Beyond Reuse Distance Analysis: Dynamic Analysis for Characterization of Data Locality Potential
Emerging computer architectures will feature drastically decreased flops/byte
(ratio of peak processing rate to memory bandwidth) as highlighted by recent
studies on Exascale architectural trends. Further, flops are getting cheaper
while the energy cost of data movement is increasingly dominant. The
understanding and characterization of data locality properties of computations
is critical in order to guide efforts to enhance data locality. Reuse distance
analysis of memory address traces is a valuable tool to perform data locality
characterization of programs. A single reuse distance analysis can be used to
estimate the number of cache misses in a fully associative LRU cache of any
size, thereby providing estimates on the minimum bandwidth requirements at
different levels of the memory hierarchy to avoid being bandwidth bound.
However, such an analysis only holds for the particular execution order that
produced the trace. It cannot estimate potential improvement in data locality
through dependence preserving transformations that change the execution
schedule of the operations in the computation. In this article, we develop a
novel dynamic analysis approach to characterize the inherent locality
properties of a computation and thereby assess the potential for data locality
enhancement via dependence preserving transformations. The execution trace of a
code is analyzed to extract a computational directed acyclic graph (CDAG) of
the data dependences. The CDAG is then partitioned into convex subsets, and the
convex partitioning is used to reorder the operations in the execution trace to
enhance data locality. The approach enables us to go beyond reuse distance
analysis of a single specific order of execution of the operations of a
computation in characterization of its data locality properties. It can serve a
valuable role in identifying promising code regions for manual transformation,
as well as assessing the effectiveness of compiler transformations for data
locality enhancement. We demonstrate the effectiveness of the approach using a
number of benchmarks, including case studies where the potential shown by the
analysis is exploited to achieve lower data movement costs and better
performance.Comment: Transaction on Architecture and Code Optimization (2014
Evaluation of Rock Characteristics for a Power Plant Site in India
Extensive geotechnical and geophysical investigations were carried out for a power plant site situated on the east coast of southern India. It is proposed to construct the foundation on rock at a depth of 18.0 m below the ground level. The geological and geotechnical characterization of the rock have been presented in this paper. Extensive boreholes were drilled up to 40.0 m to 60.0 m depth and a few boreholes up to 120.0 m depth from the ground level. Seismic crosshole tests were conducted at soil/rock strata upto 65.0 m depth for the determination of S-wave and P-wave velocity at different depths. Dilatometer tests were conducted in weathered and hard rock at 5.0 m interval up to a depth of 65.0 m. Field permeability tests were carried out in deep boreholes by single packer method. Various laboratory tests including UCC, Brazilian, and Point load tests were carried out on rock core samples. Modules obtained from UCC tests are compared with the in-situ modulus obtained from Dilatometer tests. Bearing capacity and settlement analysis are carried out for the proposed raft of about 113 m x 105 m size to be supported on rock. The allowing bearing pressure is estimated based on Rock Mass Rating, RQD and strength of rock cores. The settlement analysis is carried out using modulus obtained from Dilatometer tests and from the laboratory unconfined compression tests on rock core samples. The modulus of subgrade reaction and spring constants in vertical, horizontal and rocking modes of vibration are also evaluated for the static and seismic analysis of the raft
Tribological behaviour of RuO2 in diesel: Benthic-diatom Navicula sp. algae biodiesel
1473-1478An operating automotive engine generates more friction as well as wears in between their sliding parts when compared to an idle one, and so needs lubrication to lower this particular frictional impact. Biodiesel is surely an alternative renewable source of diesel fuel. The current research will measure the friction and wear characteristics of benthic-diatom Navicula sp. algae biodiesel with RuO2 at various concentrations. The biodiesel was studied at various blends such as B20, B20+50 ppm, and B20+100 ppm. Tests had been carried out at a speed of 1200 rpm at 75 °C under an average load of 40 kg per 1 h. Results revealed that friction and wear decreased with an increase in the concentration of RuO2 nanoparticles in biodiesel
Fun with Photons: Selective Light Induced Reactions in Solution and in Water Soluble Nano-containers
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