5,697 research outputs found

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

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    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

    Gambaran Kadar Kolesterol Pasien yang Mendapatkan Terapi Bekam

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    Consuming high cholesterol food has risk in increasing blood cholesterol level. The increased of blood cholesterol level is associated with incidence of heart disease. Many traditional treatments that can reduce cholesterol level. One of them is cupping therapy. The research aim to describe the level of cholesterol patient who received cupping therapy. The research was conduct at Rumah sehat AR-Rahmah, Pekanbaru. This descriptive study was involved 36 respondents and was selected by using purposive sampling method. The result showed an average distributions cholesterol levels on client who recieved cupping therapy. Based on the value of central tendency mean cholesterol value before cupping therapy was 200,61 mg/dl and mean of cholesterol value after cupping therapy was 197,94 mg/dl. the result showed cholesterol level on client who received cupping therapy is relatively stable and there was no significant difference. Cupping therapy process requires more time to be able to see the systemic effect of cupping therapy on cholesterol level

    Hubungan Penggunaan Backpack dengan Kejadian Low Back Pain pada Mahasiswa Universitas Riau

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    The aim of this research was to identify the correlation between using of backpack and incidence of low back pain in University of Riau's student. The design was descriptive correlational research with cross sectional approach. The sampling technique was cluster sampling with 100 respondents which was selected based on inclusion criteria. This research used questionnaire for variable of using backpack and observation sheet for incidence of low back pain. The univariate analysis was done by using distributions of frequencies and bivariate analysis was done by using chi-square test. The result showed, there was the correlation between appropriate backpack, balance, carry less and duration of using backpack with the incidence of low back pain (p value 0,003;0,000;0,000;0,000) and there was no correlation between medical history and incident of low back pain (p value 0,102). According to this research, it is necessary for University of Riau's student to select appropriate backpack, balance, carry less to reduce the incidence of low back pain

    Dynamical Characterization of Galaxies at z~4-6 via Tilted Ring Fitting to ALMA [CII] Observations

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    Until recently, determining the rotational properties of galaxies in the early universe (z>4, Universe age <1.5Gyr) was impractical, with the exception of a few strongly lensed systems. Combining the high resolution and sensitivity of ALMA at (sub-) millimeter wavelengths with the typically high strength of the [CII] 158um emission line from galaxies and long-developed dynamical modeling tools raises the possibility of characterizing the gas dynamics in both extreme starburst galaxies and normal star forming disk galaxies at z~4-7. Using a procedure centered around GIPSY's ROTCUR task, we have fit tilted ring models to some of the best available ALMA [CII] data of a small set of galaxies: the MS galaxies HZ9 & HZ10, the Damped Lyman-alpha Absorber (DLA) host galaxy ALMA J0817+1351, the submm galaxies AzTEC/C159 and COSMOS J1000+0234, and the quasar host galaxy ULAS J1319+0950. This procedure directly derives rotation curves and dynamical masses as functions of radius for each object. In one case, we present evidence for a dark matter halo of O(10^11) solar masses. We present an analysis of the possible velocity dispersions of AzTEC/C159 and ULAS J1319+0950 based on matching simulated observations to the integrated [CII] line profiles. Finally, we test the effects of observation resolution and sensitivity on our results. While the conclusions remain limited at the resolution and signal-to-noise ratios of these observations, the results demonstrate the viability of the modeling tools at high redshift, and the exciting potential for detailed dynamical analysis of the earliest galaxies, as ALMA achieves full observational capabilities.Comment: 20 pages, 6 figures, Accepted for publication in Ap

    Characterizing horizontal variability and energy spectra in the Arctic Ocean halocline

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    Energy transfer from the atmosphere into the upper Arctic Ocean is expected to become more efficient as summer sea-ice coverage decreases and multiyear ice thins due to recent atmospheric warming. However, relatively little is known about how energy is transferred within the ocean by turbulent processes from large to small scales in the presence of ice and how these pathways might change in future. This study characterises horizontal variability in several regions of the Eurasian Arctic Ocean under differing sea-ice conditions. Historic along track CTD data collected by a Royal Navy submarine during summer 1996 allows a unique examination of horizontal variability and associated wavenumber spectra within the Arctic Ocean halocline. Spectral analysis indicates that potential energy variance under perennial sea-ice in the Amundsen Basin is O(100) less than within the Marginal Ice Zone (MIZ) of Fram Strait. Spectra from all regions show a transition in scaling at wavelengths of approximately 5 to 7 km. At scales greater than the transition wavelength to 50 km, energy spectra are consistent with a k-3 scaling (where k is wavenumber) and interior quasi-geostrophic dynamics. The scaling of spectra at these scales is extremely similar between regions suggesting similar dynamics and energy exchange pathways. The k-3 scaling is steeper than typically found in regions of mid latitude open ocean. At scales below the transition wavelength to 300 m, spectra are close to a k-5/3 scaling or flatter, indicating a change in dynamics, which is potentially due to internal waves dominating variability at small scales

    The African hind's (Cephalopholis taeniops, serranidae) use of artificial reefs off Sal Island (Cape Verde): a preliminary study based on acoustic telemetry

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    The African hind Cephalopholis taeniops (Valenciennes, 1828) is one of the most important commercial demersal species caught in the Cape Verde archipelago. The species is closely associated with hard substrate and is one of the main attractions for SCUBA divers. In January 2006 a former Soviet fishing vessel - the Kwarcit - was sunk off Santa Maria Bay (Sal Island). Young C. taeniops are commonly observed in this artificial reef (AR). In order to investigate the species' use of the AR, 4 specimens were captured and surgically implanted underwater with Vemco brand acoustic transmitters. The fish were monitored daily with an active telemetry receiver for one week after release. Simultaneously, an array of 3 passive VR2 / VR2W receivers was set for 63 days, registering data that allowed an analysis of spatial, daily and short term temporal activity patterns. The results showed site fidelity to the AR, with no migrations to the nearby natural reef. The method used allowed to register a consistent higher activity during daytime and a preference for the area opposite the dominant current
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