2,333 research outputs found

    Oil quality in diesel engines with on line oil cleaning using a heated lubricating oil recycler

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    A method of cleaning the oil on line was investigatedusing a bypass fine particulate filter followed by an infra red heater to remove water and light diesel fractions in the oil. This was tested on a range of on road vehicles and a Ford 1.8 litre IDI passenger car engine on a test bed. Comparison was made with the oil quality on the same vehicles and engines without the on-line recycler. Test times were from 200 to 1500 hours of oil ageing and some of the tests showed that the oil quality was still good after 4 times the normal oil life. The results showed that the on line oil recycler cleaning system reduced the rate of fall of the TBN and rate of increase of the TAN. There was a very significant reduction in the soot in oil and the fuel dilution. There was also a consistent reduction in all the wear metals apart from copper and a decrease in the rate of reduction of oil additives. There was also measured on the Ford IDI engine a 5% reduced fuel consumption. Many of these effects were attributed to an influence of the cleaner oil on reduced engine deposits

    Closing the communications loop on the computerized peer‐assessment of essays

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    The use of self‐ and peer‐assessment is not new to higher education. Traditionally its use has required the complex and time‐consuming management of coursework submissions by the tutor, in an attempt to maintain validity and anonymity of the assessment process. In the last few years a number of computerized systems have been developed that are capable of automatically supporting, managing and performing the assessment process. The requirement for student anonymity and the release of the tutor from the process of marking have reduced the ability to develop the iterative process of feedback. This feedback is considered essential in supporting student learning and developing reflective practice. This paper describes the enhancement of a computerized assessment system to support anonymous computer‐mediated discussion between marker and marked having previously performed peer‐assessment. A detailed description is provided of the integrated assessment process, and an analysis of the use of this anonymous discussion is presented. Anonymous student feedback is presented and analyzed with respect to the perceived benefits of using the system with respect to enhancing the student learning process

    Oil quality in diesel engines with on line oil cleaning using a heated lubricating oil recycler

    Get PDF
    A method of cleaning the oil on line was investigatedusing a bypass fine particulate filter followed by an infra red heater to remove water and light diesel fractions in the oil. This was tested on a range of on road vehicles and a Ford 1.8 litre IDI passenger car engine on a test bed. Comparison was made with the oil quality on the same vehicles and engines without the on-line recycler. Test times were from 200 to 1500 hours of oil ageing and some of the tests showed that the oil quality was still good after 4 times the normal oil life. The results showed that the on line oil recycler cleaning system reduced the rate of fall of the TBN and rate of increase of the TAN. There was a very significant reduction in the soot in oil and the fuel dilution. There was also a consistent reduction in all the wear metals apart from copper and a decrease in the rate of reduction of oil additives. There was also measured on the Ford IDI engine a 5% reduced fuel consumption. Many of these effects were attributed to an influence of the cleaner oil on reduced engine deposits

    Interaction of picrotoxin with GABAA receptor channel-lining residues probed in cysteine mutants

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    We used the substituted-cysteine-accessibility method to identify the channel-lining residues in a region (257–261) near the putative cytoplasmic end of the M2 membrane-spanning segment of the rat gamma-aminobutyric acid type A (GABAA) receptor alpha 1 subunit. The residues alpha 1Val257 and alpha 1Thr261 were accessible to charged, sulfhydryl-specific reagents applied extracellularly in both the open and closed states. The accessibility of alpha 1V257C and alpha 1T261C in the closed state implies that the gate must be at least as close to the cytoplasmic end of the channel as alpha 1Val257. Also, the positively charged reagent methanethiosulfonate ethylammonium penetrated from the extracellular end of the channel to alpha 1T261C, with which it reacted, indicating that the anion-selectivity filter is closer to the cytoplasmic end of the channel than this residue is. Co-application of picrotoxin prevented the sulfhydryl reagents from reacting with alpha 1V257C but did not prevent reaction with the more extracellular residue alpha 1T261C. Picrotoxin protection of alpha 1V257C may be due to steric block by picrotoxin bound in the channel at the level of alpha 1Val257; however, if this protection is allosteric, it is not due to the induction of the resting closed state in which alpha 1V257C was accessible to sulfhydryl reagent

    Study on the Activity of PI3K/AKT, Death Receptor and 14-3-3 Mediated Signaling Pathways Regulating Hepatocyte Apoptosis during Rat Liver Regeneration

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    Studies have shown that apoptosis is closely related to the rat liver regeneration. To understand the mechanism of hepatocyte apoptosis during rat liver regeneration at the gene transcription level, the Rat Genome 230 2.0 Array was used to determine the expression changes of genes. Then the genes associated with cell apoptosis were searched by GO and NCBI databases, and cell apoptosis signaling pathways were searched by the database of QIAGEN and KEGG. Their signaling activities were calculated by spectral function E(t). The mechanism of hepatocyte apoptosis during rat liver regeneration was analyzed by Ingenuity Pathway Analysis 9.0 (IPA). The results showed that among the 27 signaling pathways regulating cell apoptosis, the E(t) values of Apoptosis signaling pathway and 14-3-3 mediated signaling pathway were significantly increased in the progression phase (6-72h after PH) of rat liver regeneration, and the E(t) values of hepatocyte apoptosis mediated by mitochondria rout were also significantly increased. The E(t) values of death receptor signaling pathway and PI3K/AKT branch of 14-3-3 mediated signaling pathway were significantly increased in the progression phase and the terminal phase (72-168h after PH) of rat liver regeneration, and the E(t) values of hepatocyte apoptosis mediated by cytomembrane route and nucleus route were also significantly increased. Conclusion: PI3K/AKT, death receptor and mitochondria branch played a key role in promoting cell apoptosis during rat liver regeneration

    Modified extragradient methods for solving variational inequalities

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    AbstractIn this paper, we propose two methods for solving variational inequalities. In the first method, we modified the extragradient method by using a new step size while the second method can be viewed as an extension of the first one by performing an additional projection step at each iteration and another optimal step length is employed to reach substantial progress in each iteration. Under certain conditions, the global convergence of two methods is proved. Preliminary numerical experiments are included to illustrate the efficiency of the proposed methods

    Loading a vapor cell magneto-optic trap using light-induced atom desorption

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    Low intensity white light was used to increase the loading rate of 87^{87}Rb atoms into a vapor cell magneto-optic trap by inducing non-thermal desorption of Rb atoms from the stainless steel walls of the vapor cell. An increased Rb partial pressure reached a new equilibrium value in less than 10 seconds after switching on the broadband light source. After the source was turned off, the partial pressure returned to its previous value in 1/e1/e times as short as 10 seconds.Comment: 7 pages, 6 figure

    Detailed quantitative comparison of half-bridge modular multilevel converter modelling methods

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    This paper presents a detailed comparison of different modelling methods of the half-bridge modular multilevel converter (HB-MMC), namely, switching function, Thevenin equivalent and averaged, considering both MMC implementations (large and reduced number of cells). The theoretical basis that underpins each modelling method are discussed. Offline PSCAD simulations are used to validate user-defined switching function and averaged MMC models against the Thevenin equivalent model provided in PSCAD library for accuracy, considering steady-state and dc fault conditions. Furthermore, the RTDS based real-time simulation results of the user-defined HB-MMC switching function model are validated against the above mentioned offline models, considering steady-state and dc short circuit fault operations. Simulation speed and efficiency of different offline HB-MMC models being studied in this paper are compared. From comprehensive corroboration of different HB-MMC models presented in this paper, it has been found that the averaged, switching function and Thevenin equivalent models produce practically identical results during steady-state and dc faults. In detailed offline and real-time simulation studies where fundamental and harmonic dynamics are of interest, switching function model is found to be faster and computational efficient compared to the Thevenin equivalent model
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