3,381 research outputs found
The Effect of Ambient Temperature on Cold Start Urban Traffic Emissions for a Real World SI Car
The influence of ambient temperature on exhaust
emissions for an instrumented Euro 1 SI car was
determined. A real world test cycle was used, based on
an urban drive cycle that was similar to the ECE urban
drive cycle. It was based on four laps of a street circuit
and an emissions sample bag was taken for each lap.
The bag for the first lap was for the cold start emissions.
An in-vehicle direct exhaust dual bag sampling
technique was used to simultaneously collect exhaust
samples upstream and downstream of the three-way
catalyst (TWC). The cold start tests were conducted
over a year, with ambient temperatures ranging from â
2°C to 32°C. The exhaust system was instrumented with
thermocouples so that the catalyst light off temperature
could be determined. The results showed that CO
emissions for the cold start were reduced by a factor of
8 downstream of catalyst when ambient temperature
rose from -2°C to 32°C, the corresponding hydrocarbon
emissions were reduced by a factor of 4. There was no
clear relationship between NOx emissions and ambient
temperature. For subsequent laps of the test circuit the
reduction of CO and HC emissions as a function of
ambient temperature was lower. The time for catalyst
light off increased by 50% as the ambient temperature
was reduced. The results show that the vehicle used is
unlikely to meet the new â 7oC cold start CO emission
regulations
20/20 eyesight: Is it enough for your child?
Early detection and correction of a vision problem is particularly important for elementary school children who are learning to read and write. After all, vision accounts for 80% of learning in the first twelve years of life. Currently most schools limit their vision screening to a basic Snellen Acuity Test. Although this test accurately assesses distance visual acuity, it does not identify the visual skills necessary for successful learning and development. This ten minute videotape was produced to educate parents and teachers on the importance of a comprehensive vision evaluation. The videotape illustrates the abilities necessary for an efficient visual system: eye health, distance and near acuities, eye tracking, focusing ability, depth perception, eye-hand coordination, eye teaming ability and visual perception
Comments on "There is no axiomatic system for the quantum theory"
In a recent paper, Nagata [1] claims to derive inconsistencies from quantum
mechanics. In this paper, we show that the inconsistencies do not come from
quantum mechanics, but from extra assumptions about the reality of observables
Frost weathering of chalk
The processes and factors that determine the heave and fracture of frost-susceptible bedrock exposed to temperature cycling above and below 0°C are little known but important to understanding of rock deformation, weathering and ground conditions. To investigate the early stages of heave, settlement and fracture of intact chalk, physical modelling experiments were performed on blocks of Saint Cyr Tuffeau and Totternhoe Clunch. Unidirectional (downward) freezing simulated seasonally frozen bedrock in non-permafrost regions, and bidirectional (upward from permafrost and downward from the surface) simulated an active layer above permafrost.
Heave and settlement of the top of the blocks were monitored in relation to rock temperature and unfrozen water content. Heave and settlement showed complex behavior that varied with moisture content, freezing regime and time. Progressive heave of wet chalk during thaw periods (simulated summers) is attributed to microcracking in near-surface permafrost. Macrocracking was favoured near the rock top during unidirectional freezing and near the permafrost table during bidirectional freezing, producing extensive fracture networks. Four processes, operating singly or in combination, account for the heave and settlement behavior: (1) thermal expansion and contraction in dry chalk; (2) volumetric expansion of freezing water, causing bursts of heave; (3) ice segregation, causing sustained heave and rock fracture; and (4) freezeâthaw cycling, causing initial consolidation and settling of wet chalk during unidirectional freezing.
The experimental data and field observations of chalk weathering profiles elucidate the nature and origin of chalk brecciation. Type 1 brecciation (angular or subangular rock fragments separated by unfilled fractures with matched sides) is attributed primarily to ice segregation. Type 2 brecciation (subangular to rounded lumps of rockâlithorelictsâset in a fine-grained matrix of the same, but softer and remoulded material) probably resulted from frost weathering and limited ground movement, particularly beneath the sides and bottoms of wet (now dry) valleys
Limb reconstruction in Ollier's disease.
We present our experience of lengthening and correction of complex deformities in the management of patients with Ollier's dysplasia (multiple enchondromatosis) from 1985 and 2002. All patients were under 18Â years with a minimum follow-up time of 2Â years (mean 9.6Â years, range 2-15Â years). There were a total of ten patients of which seven were male and three female. The mean age at presentation was 10.7Â years (range 5-17Â years; SD 3.7Â years). The total length gain was 42.3Â mm (range 30-110Â mm; SD 28.9Â mm). The number of days in external fixation was 164.8Â days (range 76-244Â days; SD 42.9Â days). The bone healing index was 32.5Â days/cm (18-50Â days/cm; SD 10.3Â days/cm). Patients with Ollier's disease have limb length inequality and angular deformities and require multiple reconstructive procedures owing to a high incidence of recurrence. We identified a tendency for the osteotomy to prematurely consolidate and advise the latency period after surgery to be 4-5Â days and for distraction to proceed at a faster rate
Particle Acceleration at Relativistic Shocks
I review the current status of Fermi acceleration theory at relativistic
shocks. I first discuss the relativistic shock jump conditions, then describe
the non-relativistic Fermi mechanism and the differences introduced by
relativistic flows. I present numerical calculations of the accelerated
particle spectrum, and examine the maximum energy attainable by this process. I
briefly consider the minimum energy for Fermi acceleration, and a possible
electron pre-acceleration mechanism.Comment: 17 pages, 4 figures. To appear in "Relativistic Flows in
Astrophysics", A.W. Guthmann, M. Georganopoulos, A. Marcowith and K.
Manolokou, eds., Lecture Notes in Pysics, Springer Verla
Growth, yield and phenology of 2 hybrid papayas (Carica papaya L.) as influenced by method of water application
Highly variable, outcrossed papaya lines irrigated with overhead sprinklers were grown at Yarwun (151.3ËE, 23.75ËS) in Queensland, Australia. The inherent variability made scientifically based comparative studies impractical. The advent of uniform hybrid papaya lines allowed the testing of 2 of these hybrids under 3 irrigation methods, 2 of which had the potential to greatly reduce water use compared with overhead sprinklers. Yields of 92 t/ha.year were achieved by both papaya Hybrids 29 and 1E. Water application method did not influence yield. About 26% of plants were lost due to the phytoplasma diseases dieback, yellow crinkle and mosaic over the life of the trial. Downward yield fluctuations were related to poor fruit set in winter when pollinators (Family Sphingidae) were not present and growth was slow due to hot dry periods affecting fruit set. The resultant fruit (about 6 months later) were small and reduced in number.
Irrigation with overhead sprinklers using saline water (1400â4000 S/cm) damaged leaves and reduced growth of plants. Winter spot was most severe in July, August and September, in Hybrid 29 with overhead irrigation.
Height of plants 13 weeks after planting was greater under trickle irrigation due to less damage from the saline water supply than in the overhead sprinkler treatment. Hybrid 29 set fruit at 94.3 cm above ground compared with 117.6 cm for Hybrid 1E
Violation of local realism vs detection efficiency
We put bounds on the minimum detection efficiency necessary to violate local
realism in Bell experiments. These bounds depends of simple parameters like the
number of measurement settings or the dimensionality of the entangled quantum
state. We derive them by constructing explicit local-hidden variable models
which reproduce the quantum correlations for sufficiently small detectors
efficiency.Comment: 6 pages, revtex. Modifications in the discussion for many parties in
section 3, small erros and typos corrected, conclusions unchange
Polarization Correlations of 1S0 Proton Pairs as Tests of Bell and Wigner Inequalities
In an experiment designed to overcome the loophole of observer dependent
reality and satisfying the counterfactuality condition, we measured
polarization correlations of 1S0 proton pairs produced in 12C(d,2He) and
1H(d,He) reactions in one setting. The results of these measurements are used
to test the Bell and Wigner inequalties against the predictions of quantum
mechanics.Comment: 8 pages, 4 figure
Solving Large-Scale Optimization Problems Related to Bell's Theorem
Impossibility of finding local realistic models for quantum correlations due
to entanglement is an important fact in foundations of quantum physics, gaining
now new applications in quantum information theory. We present an in-depth
description of a method of testing the existence of such models, which involves
two levels of optimization: a higher-level non-linear task and a lower-level
linear programming (LP) task. The article compares the performances of the
existing implementation of the method, where the LPs are solved with the
simplex method, and our new implementation, where the LPs are solved with a
matrix-free interior point method. We describe in detail how the latter can be
applied to our problem, discuss the basic scenario and possible improvements
and how they impact on overall performance. Significant performance advantage
of the matrix-free interior point method over the simplex method is confirmed
by extensive computational results. The new method is able to solve problems
which are orders of magnitude larger. Consequently, the noise resistance of the
non-classicality of correlations of several types of quantum states, which has
never been computed before, can now be efficiently determined. An extensive set
of data in the form of tables and graphics is presented and discussed. The
article is intended for all audiences, no quantum-mechanical background is
necessary.Comment: 19 pages, 7 tables, 1 figur
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