An experimental study of the dual-fuel performance of a small compression ignition diesel engine operating with three gaseous fuels

A dual-fuel engine is a compression ignition (CI) engine where the primary gaseous fuel source is premixed with air as it enters the combustion chamber. This homogenous mixture is ignited by a small quantity of diesel, the ‘pilot’, that is injected towards the end of the compression stroke. In the present study, a direct-injection CI engine, was fuelled with three different gaseous fuels: methane, propane, and butane. The engine performance at various gaseous concentrations was recorded at 1500 r/min and quarter, half, and three-quarters relative to full a load of 18.7 kW. In order to investigate the combustion performance, a novel three-zone heat release rate analysis was applied to the data. The resulting heat release rate data are used to aid understanding of the performance characteristics of the engine in dual-fuel mode. Data are presented for the heat release rates, effects of engine load and speed, brake specific energy consumption of the engine, and combustion phasing of the three different primary gaseous fuels. Methane permitted the maximum energy substitution, relative to diesel, and yielded the most significant reductions in CO2. However, propane also had significant reductions in CO2 but had an increased diffusional combustion stage which may lend itself to the modern high-speed direct-injection engine

Estimating the amount of vorticity generated by cosmological perturbations in the early universe

We estimate the amount of vorticity generated at second order in cosmological perturbation theory from the coupling between first order energy density and non-adiabatic pressure, or entropy, perturbations. Assuming power law input spectra for the source terms, and working in a radiation background, we calculate the wave number dependence of the vorticity power spectrum and its amplitude. We show that the vorticity generated by this mechanism is non-negligible on small scales, and hence should be taken into consideration in current and future CMB experiments.Comment: 9 pages, revtex4, 1 figure; v2: typos and minor error corrected, result unchange

Black hole entropy from an SU(2)-invariant formulation of Type I isolated horizons

A detailed analysis of the spherically symmetric isolated horizon system is performed in terms of the connection formulation of general relativity. The system is shown to admit a manifestly SU(2) invariant formulation where the (effective) horizon degrees of freedom are described by an SU(2) Chern-Simons theory. This leads to a more transparent description of the quantum theory in the context of loop quantum gravity and modifications of the form of the horizon entropy.Comment: 30 pages, 1 figur

Kemampuan Fission Teripang Holothuria Edulis Dan Holothuria Leucospilota (Holothuridae) Ukuran Yang Berbeda Di Kepulauan Karimunjawa

Sea cucumber is one of the important natural resources of Karimunjawa Islands. Because it has a high economic value, so fishermen exploit excessively it may reduce the population. Naturally sea cucumbers are able to reproduce asexually by fission process (division). This study aimed to determine the ability of fission and regeneration of sea cucumber Holothuria edulis and Holothuria leucospilota having different body sizes. The research was conducted in October-December 2011, in Karimunjawa waters. Jepara. Stimulation of fission carried out by binding sea cucumbers with a rubber band at 1/3 position of the anterior part. The results showed that the sea cucumber H. edulis and H. leucospilota successfully split at the 24. The difference in the size of cucumbers affect the fission time, while the intensity of regeneration of bigger sea cucumbers has higher value than a small one. The rate of fission of H. edulis and H. leucospilota 95-100%. Regeneration intensity of bigger H. edulis and H. leucospilota are higher than the small size. Posterior part of the body has higher survival rate is than the anterior

POEM: Pricing Longer for Edge Computing in the Device Cloud

Multiple access mobile edge computing has been proposed as a promising technology to bring computation services close to end users, by making good use of edge cloud servers. In mobile device clouds (MDC), idle end devices may act as edge servers to offer computation services for busy end devices. Most existing auction based incentive mechanisms in MDC focus on only one round auction without considering the time correlation. Moreover, although existing single round auctions can also be used for multiple times, users should trade with higher bids to get more resources in the cascading rounds of auctions, then their budgets will run out too early to participate in the next auction, leading to auction failures and the whole benefit may suffer. In this paper, we formulate the computation offloading problem as a social welfare optimization problem with given budgets of mobile devices, and consider pricing longer of mobile devices. This problem is a multiple-choice multi-dimensional 0-1 knapsack problem, which is a NP-hard problem. We propose an auction framework named MAFL for long-term benefits that runs a single round resource auction in each round. Extensive simulation results show that the proposed auction mechanism outperforms the single round by about 55.6% on the revenue on average and MAFL outperforms existing double auction by about 68.6% in terms of the revenue.Comment: 8 pages, 1 figure, Accepted by the 18th International Conference on Algorithms and Architectures for Parallel Processing (ICA3PP

Prevalence and severity of viral hepatitis in Pakistani pregnant women: A five year hospital based study

A hospital based observational study was carried out on pregnant women presenting with either acute hepatitis or fulminant hepatic failure (FHF), during the past years. Of 53 patients, 20 (38%) developed FHF.Non-A, Non-B was the commonest cause (62%) followed by hepatitis B in 17% and hepatitis A in 4% cases. Eight women expired (case fatality rate 15%) with a high maternal mortality (62%) caused by NANB hepatitis. Perinatal mortality was 30%. Poor prognostic factors identified were lack of antenatal care, severity of jaundice, history of somnolence, gastrointestinal bleeding and a high grade of encephalopathy

First impressions and perceived roles: Palestinian perceptions on foreign aid

This paper summarizes some results of a wider research on foreign aid that was conducted in the West Bank and Gaza Strip in 2010. It seeks to describe the impressions and feelings of Palestinian aid beneficiaries as well as the roles and functions they attached to foreign aid. To capture and measure local perceptions on Western assistance a series of individual in depth interviews and few focus group interviews were conducted in the Palestinian territories. The interview transcripts were processed by content analysis. As research results show — from the perspective of aid beneficiaries — foreign aid is more related to human dignity than to any economic development. All this implies that frustration with the ongoing Israeli-Palestinian conflict inevitably embraces the donor policies and practices too