2,257 research outputs found
Relaxation of Collective Excitations in LJ-13 Cluster
We have performed classical molecular dynamics simulation of
cluster to study the behavior of collective excitations. In the solid ``phase''
of the cluster, the collective oscillation of the monopole mode can be well
fitted to a damped harmonic oscillator. The parameters of the equivalent damped
harmonic oscillator-- the damping coefficient, spring constant, time period of
oscillation and the mass of the oscillator -- all show a sharp change in
behavior at a kinetic temperature of about . This marks yet another
characteristic temperature of the system, a temperature below which
collective excitations are very stable, and at higher temperatures the single
particle excitations cause the damping of the collective oscillations. We argue
that so long as the cluster remains confined within the global potential energy
minimum the collective excitations do not decay; and once the cluster comes out
of this well, the local potential energy minima pockets act as single particle
excitation channels in destroying the collective motion. The effect is manifest
in almost all the physical observables of the cluster.Comment: Revised and enlarged. 6 pages RevTeX style. 7 eps figures available
on request. To appear in J Chem Phy
Unusually high landings of some penaeid prawns at Bombay
An unusual high landings of mainly two species of penaeid prawns, Metapenaeus monoceros and Metapenaeopsis stridulans, in the New Ferry wharf, an important trawl landing centre in Greater Bombay,have been reported in October and November ,1982 and the particulars are illustrated
Heavy landing of Parapenaeopsis stylifera (M. Edw.) at Bombay during post-monsoon 1984
New Ferry Wharf is a major fish landing centre in Greater Bombay where fishing activity generally resumes in September after a period of lull during the southwest monsoon. This centre accounted for an annual (July-June) average of 7,530 tonnes of penaeid prawns of which Parapenaeopsis stylifera constituted 59.6%. The size (total length) of P. stylifera ranged from 58 to 103 mm for males and from 63 to 118 mm for females with the modal size at 83 mm and 103 mm for the respective sexes. The incidence of such huge catch all along the coast at about the same time was probably triggered by some oceanographic factors such as large scale upwelling of oxygen minimum layer which might have pushed the stock towards the shore
Crowd Counting with Decomposed Uncertainty
Research in neural networks in the field of computer vision has achieved
remarkable accuracy for point estimation. However, the uncertainty in the
estimation is rarely addressed. Uncertainty quantification accompanied by point
estimation can lead to a more informed decision, and even improve the
prediction quality. In this work, we focus on uncertainty estimation in the
domain of crowd counting. With increasing occurrences of heavily crowded events
such as political rallies, protests, concerts, etc., automated crowd analysis
is becoming an increasingly crucial task. The stakes can be very high in many
of these real-world applications. We propose a scalable neural network
framework with quantification of decomposed uncertainty using a bootstrap
ensemble. We demonstrate that the proposed uncertainty quantification method
provides additional insight to the crowd counting problem and is simple to
implement. We also show that our proposed method exhibits the state of the art
performances in many benchmark crowd counting datasets.Comment: Accepted in AAAI 2020 (Main Technical Track
Interaction of mixed mode loading on cyclic debonding in adhesively bonded composite joints
A combined experimental and analytical investigation of an adhesively-bonded composite joint was conducted to characterize the fracture mode dependence of cyclic debonding. The system studied consisted of graphite/epoxy adherends bonded with EC 3445 adhesive. Several types of specimens are tested which provide the cyclic debond growth rate measurements under various load conditions: mode 1, mixed mode 1 to 2, and mostly mode 2. This study shows that the total strain-energy-release rate is the governing factor for cyclic debonding
On placement and dynamic power control of femtocells in LTE HetNets
Femto cells a.k.a. Low Power Nodes (LPNs) are used to improve indoor data rates as well as to reduce traffic load on macro Base Stations (BSs) in LTE cellular networks. These LPNs are deployed inside office buildings and residential apartment complexes to provide high data rates to indoor Users. With high SINR (Signal-to-Interference plus Noise Ratio) the users experience good throughput, but the SINR decreases significantly because of interference and obstacles such as building walls, present in the communication path. So, efficient placement of Femtos in buildings while considering Macro-Femto interference is very crucial for attaining desirable SINR. At the same time, minimizing the power leakage in order to improve the signal strength of outdoor users in a high interference (HIZone) around the building area is important. In our work, we have considered obstacles (walls, floors) and interference between Macro and Femto BSs. To be fair to both indoor and outdoor users, we designed an efficient placement and power control SON (Self organizing Network) algorithm which optimally places Femtos and dynamically adjusts the transmission power of Femtos based on the occupancy of Macro users in the HIZone. To do this, we solve two Mixed Integer Programming (MIP) methods namely: Minimize number of Femtos (MinNF) method which guarantees threshold SINR (SINRTh) -2dB for all indoor users and optimal Femto power (OptFP) allocation method which guarantees SINRTh (- 4 dB) for indoor users with the Macro users SINR degradation as lesser than 2dB
A novel scheduling algorithm to maximize the D2D spatial reuse in LTE networks
In order to offload base station (BS) traffic and to enhance efficiency of spectrum, operators can activate many Device-to-Device (D2D) pairs or links in LTE networks. This increases the overall spectral efficiency because the same Resource Blocks (RBs) are used across cellular UEs (CUEs) (i.e., all UEs connected to BS for both C-Plane and D-plane communication) and D2D links (i.e., where the UEs are connected to BS only for C-plane communication). However, significant interference problems can be caused by D2D communications as the same RBs are being shared. In our work, we address this problem by proposing a novel scheduling algorithm, Efficient Scheduling and Power control Algorithm for D2Ds (ESPAD), which reuses the same RBs and tries to maximize the overall network throughput without affecting the CUEs throughput. ESPAD algorithm also ensures that Signal to Noise plus Interference Ratio (SINR) for each of the D2D links is maintained above a certain predefined threshold. The aforementioned properties of ESPAD algorithm makes sure that the CUEs do not experience very high interference from the D2Ds. It is observed that even when the SINRdrop (i.e., maximum permissible drop in SINR of CUEs) is as high as 10 dB, there is no drastic decrease in CUEs throughput (only 3.78%). We also compare our algorithm against other algorithms and show that D2D throughput improves drastically without undermining CUEs throughput
Turbulent jet in confined counterflow
The mean flowfield of a turbulent jet issuing into a confined, uniform counterflow was investigated computationally. Based on dimensional analysis, the jet penetration length was shown to scale with jet-to-counterflow momentum flux ratio. This scaling and the computational results reproduce the well-known correct limit of linear growth of the jet penetration length for the unconfined case when the momentum flux ratio is small. However, for the high momentum flux ratio case corresponding to the confinement, the jet penetration length is shown to reach an asymptotic limit of about 3.57 times the confining duct diameter. This conclusion is contrary to the existing results which predict indefinite growth. A simple modification of an existing similarity solution for the jet in an unconfined counterflow provides a convenient framework for presenting the results of the flowfield and jet penetration length
Sealants for preventing dental caries in primary teeth
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: To evaluate the effects of sealants in preventing pit and fissure caries in primary molars.</p
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The impact of monsoon intraseasonal variability on renewable power generation in India
India is increasingly investing in renewable technology to meet rising energy demands, with hydropower and other renewables comprising one-third of current installed capacity. Installed wind-power is projected to increase 5-fold by 2035 (to nearly 100GW) under the International Energy Agency’s New Policies scenario. However, renewable electricity generation is dependent upon the prevailing meteorology, which is strongly influenced by monsoon variability. Prosperity and widespread electrification are increasing the demand for air conditioning, especially during the warm summer.
This study uses multi-decadal observations and meteorological reanalysis data to assess the impact of intraseasonal monsoon variability on the balance of electricity supply from wind-power and temperature-related demand in India. Active monsoon phases are characterised by vigorous convection and heavy rainfall over central India. This results in lower temperatures giving lower cooling energy demand, while strong westerly winds yield high wind-power output. In contrast, monsoon breaks are characterised by suppressed precipitation, with higher temperatures and hence greater demand for cooling, and lower wind-power output across much of India. The opposing relationship between wind-power supply and cooling demand during active phases (low demand, high supply) and breaks (high demand, low supply) suggests that monsoon variability will tend to exacerbate fluctuations in the so-called demand-net-wind (i.e., electrical demand that must be supplied from non-wind sources).
This study may have important implications for the design of power systems and for investment decisions in conventional schedulable generation facilities (such as coal and gas) that are used to maintain the supply/demand balance. In particular, if it is assumed (as is common) that the generated wind-power operates as a price-taker (i.e., wind farm operators always wish to sell their power, irrespective of price) then investors in conventional facilities will face additional weather-volatility through the monsoonal impact on the length and frequency of production periods (i.e. their load-duration curves)
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