This paper presents the impact of acetoacetic esters and di-carboxylic acid esters on the lubrication properties of automotive diesel. Three alkyl acetoacetates and seven di-carboxylic esters were ...used as lubricating additives on two low sulfur diesel fuels, at seven different concentrations of 50, 100, 500, 750, 1000, 1500 and 2000
ppm. Tribological experiments carried out on the high frequency reciprocating rig (HFRR) showed that only two of the three acetoacetic esters used, provide satisfactory mean wear scar diameter (WS 1.4) of less than 460
μm, at the concentration level of 750
ppm. In the case of di-carboxylic acid esters, the effective concentration was 500
ppm or higher.
To reduce their fuel related logistic burden, NATO Armed Forces are advancing the use of a single fuel for both aircraft and ground equipment. To this end, F-34 is replacing distillate diesel fuel in ...many applications. However, tests conducted with kerosene on High Frequency Reciprocating Rig, showed that it causes unacceptable wear due to the poor lubricity of aviation fuel. In order to make this type of fuel compatible with direct injection compression engines, tests were carried out with ten mono–carboxylic acid esters to improve the lubricity of kerosene. Tribological results showed that all esters tested, were suitable for increasing the kerosene lubricity to a satisfactory level. Among the esters of the same molecular type, those having the ester group around the middle of the molecule appear to have better lubrication performance.
This paper presents the impact of alkyl ethers and alcohols on the lubricity of automotive diesel. Seven ethers and five alcohols were used as lubricating additives on two low sulfur diesel fuels, at ...the concentration range of 50–2000
ppm. Tribological experiments carried out on the high frequency reciprocating rig showed that six of seven ethers used provide satisfactory mean wear scar diameter (WS 1.4) of less than 0.46
mm, at the concentration levels of 750–1500
ppm. Among the ethers of the same molecular type, those having the oxygen in the middle of the molecule appeared to have marginally better lubrication performance for some concentration ranges. In the case of alcohols, the effective concentration was 750
ppm or higher. Overall, alcohols appear to be better lubricants than ethers at high concentrations, maybe due to their more pronounced polar nature.
Vegetable oils are produced from numerous oil seed crops. While all vegetable oils have high-energy content, most require some processing to assure safe use in internal combustion engines. Some of ...these oils already have been evaluated as substitutes for diesel fuels. With the exception of rape seed oil which is the principal raw material for biodiesel fatty acid methyl esters, sunflower oil, corn oil and olive oil, which are abundant in Southern Europe, along with some wastes, such as used frying oils, appear to be attractive candidates for biodiesel production. In this paper, fuel consumption and exhaust emissions measurements from a single cylinder, stationary diesel engine are described. The engine was fueled with pure marine diesel fuel and blends containing two types of biodiesel, at proportions up to 50%. The two types of biodiesel appeared to have equal performance, and irrespective of the raw material used for their production, their addition to the marine diesel fuel improved the particulate matter, unburned hydrocarbons, nitrogen oxide and carbon monoxide emissions.
The present study examines the absorption capacity of five different types of materials for oil spills clean up. The absorbents were a commercial cellulosic material from processed wood, a commercial ...synthetic organic fiber from polypropylene and three commercial types of local expanded perlite from the island of Milos. The absorption capacities of the above materials were evaluated in a wet as well as a dry environment with different types of petroleum products. The results showed that commercial types of perlite, in some cases, have absorption capacities comparable to natural and synthetic organic materials used for clean-up applications. The enhancement of the hydrophobic properties of perlite can result in better performance in a water bath. The nature of the spilled oil proved to play an important role in the selection of the proper absorbing material. Overall, the results suggested that partial substitution of commercial synthetic sorbents by mineral materials widely produced in Greece for oil spill clean-up operations is possible, given their friendliness to the environment and their local abundancy.
The main objective of this work is to investigate a viable alternative for the final disposal of sewage sludge from urban wastewater treatment plants using a mixture with cement and jarosite/alunite ...(J/A) precipitate to develop new construction materials. J/A precipitate is a waste product of a new hydrometallurgical process, which was developed in order to treat economically low-grade nickel oxide ores. In the current study two methods were used for the hardening of the stabilized/solidified products: (1) in laboratory conditions and (2) in accelerated conditions (autoclave treatment).
For this purpose, mortar prism samples of 4
×
4
×
16
cm in dimension were prepared, composed of 50% sewage sludge, 30% cement and 20% jarosite/alunite. The samples were treated in an autoclave for 3
h at a temperature of 200
°C and a pressure of 16
bar as well as in laboratory conditions for 28 and 90 days. Compressive and bending strength, while chemical, XRD, thermal analysis, as well as tests of leaching, were tested according to the standard/principal methods of toxicity characteristics leaching procedure (TCLP) and CEN/TS 14405. The results indicated that stabilized/solidified products can be produced for use in construction and that the heavy metals of sludge can be contained in the cement and jarosite/alunite mixture.
Auditory physiology: present trends TEAS, D. C
Annual review of psychology,
1989, 1989-00-00, 1989-01-00, 19890101, Letnik:
40, Številka:
1
Journal Article
Recenzirano
Recent trends in auditory physiology are discussed. Particular emphasis in this discussion focuses on studies of inner and outer hair cells, auditory localization and sensory information transmission.