The impact of ignition delay and further fuel properties on combustion and emissions in a compression ignition engine

Better understanding of combustion and formation of exhaust gas pollutants of fuels is needed in order to meet stringent regulation standards of a diesel engine. The cetane number is one of the most-cited indicators of diesel fuel quality. This paper presents experimental studies with a wide range of fuels to investigate the effect of cetane number on combustion and exhaust emissions (CO, NOx, PM, particle number size distribution). The fuel ignitability was controlled in two different ways: naturally, by using seven fuels (Dearomatised Hydrotreated Stream, Hydrotreated Non-Dearomatised Stream, Soy Methyl Ester, Rapeseed Methyl Ester, Heavy Paraffinic Stream, C10-C14 Paraffins, and C14-C17 Paraffins) with different cetane numbers, and through the use of an ignition improver blended into a single base fuel (Hydrotreated Non-Dearomatised Stream (NDH)) to change the ignition chemistry of the fuel while keeping physical properties unchanged. The tests were performed in naturally-aspirated single-cylinder DI diesel engine at 1200 rpm and 600 bar injection pressure at 4 bar and 6 bar IMEP. The engine tests were carried out at constant fuel injection timing and constant start of combustion timing. A strong positive correlation was found between ignition delay and CO emissions. The effect of physical and chemical properties of the fuel on NOx and particulate emissions became more dominant at higher load. Overall the results showed that changes in the fuel physical properties and molecular structure, in particular, the incorporation of oxygen, impacted on combustion and emissions through various routes in addition to the effects of ignition delay only

Non-relativistic Lee Model on two Dimensional Riemannian Manifolds

This work is a continuation of our previous work (JMP, Vol. 48, 12, pp. 122103-1-122103-20, 2007), where we constructed the non-relativistic Lee model in three dimensional Riemannian manifolds. Here we renormalize the two dimensional version by using the same methods and the results are shortly given since the calculations are basically the same as in the three dimensional model. We also show that the ground state energy is bounded from below due to the upper bound of the heat kernel for compact and Cartan-Hadamard manifolds. In contrast to the construction of the model and the proof of the lower bound of the ground state energy, the mean field approximation to the two dimensional model is not similar to the one in three dimensions and it requires a deeper analysis, which is the main result of this paper.Comment: 18 pages, no figure

Glassy Dynamics of Protein Folding

A coarse grained model of a random polypeptide chain, with only discrete torsional degrees of freedom and Hookean springs connecting pairs of hydrophobic residues is shown to display stretched exponential relaxation under Metropolis dynamics at low temperatures with the exponent $\beta\simeq 1/4$, in agreement with the best experimental results. The time dependent correlation functions for fluctuations about the native state, computed in the Gaussian approximation for real proteins, have also been found to have the same functional form. Our results indicate that the energy landscape exhibits universal features over a very large range of energies and is relatively independent of the specific dynamics.Comment: RevTeX, 4 pages, multicolumn, including 5 figures; larger computations performed, error bars improve

The Lippmann–Schwinger Formula and One Dimensional Models with Dirac Delta Interactions

We show how a proper use of the Lippmann–Schwinger equation simplifies the calculations to obtain scattering states for one dimensional systems perturbed by N Dirac delta equations. Here, we consider two situations. In the former, attractive Dirac deltas perturbed the free one dimensional Schrödinger Hamiltonian. We obtain explicit expressions for scattering and Gamow states. For completeness, we show that the method to obtain bound states use comparable formulas, although not based on the Lippmann–Schwinger equation. Then, the attractive N deltas perturbed the one dimensional Salpeter equation. We also obtain explicit expressions for the scattering wave functions. Here, we need regularisation techniques that we implement via heat kernel regularisation

Efek Variasi Waktu Ball Milling terhadap Karakteristik Elektrokimia Sel Superkapasitor Berbasis Karbon

Supercapacitor electrodes from rubber wood saw dust (RWSD) have been fabricated using experiment method to study the ball milling variation time on performance of the supercapacitor cells. The carbon electrodes were prepared with time variation of 20, 40, and 80 hours and thickness of 0.2 mm. Carbon electrodes were carbonized at 600oC and followed by physical activation method in CO2 gas atmosphere on the constant temperature of 900o C, and chemical activation was performed by KOH as an activating agent. Densities of the electrodes were 0.849 g/cm3 , 0.892 g/cm3 , 0.982 g/cm3 respectively. XRD measurement showed the peaks of carbon electrodes at 2θ of 24.091o and 44.473o which represented the presence of carbon materials with their crystal orientation of (002) and (100). SEM micrograph on magnification of 1000X showed that the pore distribution of the carbon electrodes dominant on macropores. This study found that the effects of increasing of ball milling time influenced the electrochemical properties of supercapacitor electrodes fro m RWSD. The optimum supercapacitor performance was found on 20 hour milling time electrode and had a specific capacitance of 55.414 F/g

Stock Pricing Analysis of PT. LEN as Alternative Sources of Fund Through the Initial Public Offering (IPO)

PT. LEN is one of state owned companies (BUMN) in Indonesia which is engaged in technology industries. As one of state owned companies (BUMN) which enroll in strategic industries, PT. LEN has a very important role in supporting the growth of Indonesia\u27s development, PT. LEN\u27s business performance has successfully led PT. LEN as a trillion company. In 2011, the life cycle of this company has been projected from phase stability to phase growth. Nevertheless, one issue has arisen when the growth of the company is hampered by funding issue, especially the lack of capital to run the projects. The growth of revenues become unbalanced with working capital, especially liquid working capital (cash). The objective of the company is to Go Public with huge amount of capital which can support the business activities and also to strengthen the capital structure and the liquidity of assets. The sales revenue from some of its stocks is used as an alternative source of fund apart from bank loans. The fund is used to expand the company\u27s activities, to build the facility of developing system, and also to build fabrication workshop. The total amount of fund needed is 590 billion. During the IPO process, there are several things to be concerned, internally and externally. From the company\u27s internal perspective, several things to be be concerned are company\u27s feasibility studies in doing IPO. From the external perspective will affect investors\u27 interest to the company. This thesis uses discounted cash flow as a method to calculate the valuation of the company. This method is used to value stock\u27s price and the amount of stocks issued by PT. LEN for IP process so the price will be interesting to the investors. Other than to fulfill the needs of source funding, IPO process is also one of the program to privatize the state owned companies in Indonesia which is included in BUMN\u27s Masterplan 2010-2014

A Many-body Problem with Point Interactions on Two Dimensional Manifolds

A non-perturbative renormalization of a many-body problem, where non-relativistic bosons living on a two dimensional Riemannian manifold interact with each other via the two-body Dirac delta potential, is given by the help of the heat kernel defined on the manifold. After this renormalization procedure, the resolvent becomes a well-defined operator expressed in terms of an operator (called principal operator) which includes all the information about the spectrum. Then, the ground state energy is found in the mean field approximation and we prove that it grows exponentially with the number of bosons. The renormalization group equation (or Callan-Symanzik equation) for the principal operator of the model is derived and the $\beta$ function is exactly calculated for the general case, which includes all particle numbers.Comment: 28 pages; typos are corrected, three figures are adde

The Incremental Garbage Collection of Processes

Key Words and Phrases: garbage collection, multiprocessing systems, processor scheduling. "lazy evaluation, "eager" evaluation. CR Categories: 3.60, 3.80, 4.13, 4.22, 4.32. This report describes research done at the Artificial Intelligence Laboratory of the Massachusetts Institute of Technology. Support for the laboratory's artificial intelligence research is provided in part by the Advanced Research Projects Agency of the Department of Defense under Office of Naval Research contract N00014-75-C-0522. This paper was presented at the AI*PL Conference at Rochester, N.Y. in August, 1977.This paper investigates some problems associated with an argument evaluation order that we call "future" order, which is different from both call-by-name and call-by-value. In call-by-future, each formal parameter of a function is bound to a separate process (called a "future") dedicated to the evaluation of the corresponding argument. This mechanism allows the fully parallel evaluation of arguments to a function, and has been shown to augment the expressive power of a language. We discuss an approach to a problem that arises in this context: futures which were thought to be relevant when they were created become irrelevant through being ignored in the body of the expression where they were bound. The problem of irrelevant processes also appears in multiprocessing problem-solving systems which start several processors working on the same problem but with different methods, and return with the solution which finishes first. This parallel method strategy has the drawback that the processes which are investigating the losing methods must be identified, stopped, and re-assigned to more useful tasks. The solution we propose is that of garbage collection. We propose that the goal structure of the solution plan be explicitly represented in memory as part of the graph memory (like Lisp's heap) so that a garbage collection algorithm can discover which processes are performing useful work, and which can be recycled for a new task. An incremental algorithm for the unified garbage collection of storage and processes is described.MIT Artificial Intelligence Laboratory Department of Defense Advanced Research Projects Agenc