91 research outputs found
A geochemical method to trace the taphonomic history of reworked bones in sedimentary settings
No full textRare earth element (REE) signatures can be used to identify the original mode of deposition of fossil bones and teeth that have been reworked. This new technique may resolve the notoriously difficult problem of assessing the amount of transport or reworking undergone by fossil bones and teeth on the basis of physical parameters, such as degree of abrasion. Different REE signals characterize different pore-water environments. Bones and teeth, composed of apatite, incorporate REEs rapidly during early diagenesis, and the REE signature in the bone is controlled by that of the surrounding pore waters. Reworked bones and teeth may show REE traces suggesting early-diagenetic pore-water conditions different from those indicated by in situ sedimentary or geochemical evidence. This situation is demonstrated in a case study from the Rhaetian (latest Triassic) of southwest England, where different bone beds are compared. In one case, the original environmental setting of reworked bone is traced by matching REE traces with contemporaneous unreworked bone assemblages in neighboring areas
A nesting trace with eggs for the Cretaceous theropod dinosaur Troodon formosus
No full textAn unusual trace containing eggs of the 50 kg-plus theropod dinosaur, Troodon formosus, represents one of the best preserved dinosaur nests. This unique specimen (MOR 963) represents the actual nest structure and the direct product of Troodon behavior. The trace comes from the Campanian, Late Cretaceous Two Medicine Formation of Montana, and consists of a bowl-shaped depression with an internal area of similar to 1m(2) surrounded by a distinct rim. A clutch of 24 tightly-placed eggs sat in the center and both nest and clutch show bilateral symmetry about a north-south axis. The trace occurs within a moderately well-developed micritic paleosol. A physically and chemically distinct mudstone covered the nest and represents overbank deposition. The nest protected the eggs by creating a suitable micro-environment during the lengthy egg-laying and incubation periods. Clutch and nest size, shape, and symmetry and low organic carbon of the overlying mudstone suggests brooding rather than incubation with vegetative cover, although the latter cannot be ruled out. The nest probably played no role in the post-hatching care of precocial Troodon young. Reproductive traits indicated by MOR 963 show that Troodon possessed plesiomorphies shared with crocodilians (some burial of eggs and lack of egg rotation), apomorphies shared with birds (open nests, exposed eggs, and incubation by a brooding adult), but also at least one unusual feature (steeply-inclined eggs) not found in either extant archosaur group. Some reproductive features typically associated with living birds first evolved within non-avian coelurosaurian theropods like Troodon
Variation of REE patterns in dinosaur bones from North West Montana: implications for taphonomy and preservation
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CNG as a Feasible Replacement for the U.S. Transportation Sector
No full textFor many years there has been much attention on reducing U.S. fuel imports to improve the nation\u27s energy independence. Much of the focus has been on the transportation sector, as it accounts for 28% of total U.S. energy consumption. This thesis examines compressed natural gas (CNG) as a possible alternative fuel for the U.S. transportation sector. To fully explore this possibility, it is essential to understand both the supply and demand sides of the problem. This research examines the availability and adequacy of CNG as a full or partial fuel replacement for U.S. transportation fuels, the factors that prevent CNG from being a widely used transportation fuel, the costs and benefits of using CNG as a vehicle fuel, and ways in which to make CNG more cost-effective. The author applies the Analytic Hierarchy Process to determine the optimum short-term and long-term scenarios for CNG use in the U.S. transportation sector
Comparison of CNG and diesel trucks profitability
No full textLõputöö eesmärk oli anda hinnang CNG veokite kasutamise võimalustele võrrelduna diiselveokitega maanteevedude teostamisel. Lõpustöös uuriti kahte ettevõtet, millest esimene tegeleb toiduainetootmisega, teine on transpordiettevõte. Mõlemad ettevõtted kasutavad nii diiselveokeid kui CNG veokeid. Lõputöös viidi läbi küsitlus kahe ettevõtte seas, analüüsiti veokitega seotud kulusid ja veoringe.
Lõputöös läbiviidud küsitlus näitas, et mõlemad uuritud ettevõtted kasutavad peamiselt diiselveokeid ning CNG veokeid on kasutusel vähem. Seoses CNG hinna kallinemisega on CNG veokite kasutamist vähendatud ja lähitulevikus, enne kui CNG hind võrreldes diislikütusega ei odavne, ettevõtted CNG veokeid juurde soetada ei kavatse.
Uuringu tulemused näitavad, et praeguste CNG hindade juures ei ole osutunud CNG veokid majanduslikult tasuvaks. Selleks, et CNG veokeid tasuks kasutada, on vajalik, et CNG hind oleks võrreldes diislikütusega soodsam, kuivõrd CNG veokid on kallimad ning lühema hooldusvälba tõttu on nende hoolduskulud kõrgemad. Tulenevalt CNG veokite lühemast tankevälbast ja CNG tanklate vähesusest Eestis, muudab CNG veokite kasutamine veoringide koostamise keerulisemaks ja teatud määral pikendab veoringe. Viimane asjaolu omakorda vähendab CNG veokite majanduslikku tasuvust.
Uuritud ettevõtted leidsid, et CNG hinna tõus on mõjunud CNG veokite kasutamisele ebasoodsalt. Selle tulemusena on kasvanud ettevõtete transpordikulud. Kuigi ka diislikütuse hind on tõusnud, on see toimunud väiksemas ulatuses. Üks uuritud ettevõtetest fikseeris CNG kütuse hinna, mis ei toonud kulude kasvu, sest varasemalt oli sõlmitud kütusemüüjaga pikaajaline hinnakokkulepe.
Küsitlusele vastanud ettevõtted ei olnud kindlad, kas nad hakkavad tulevikus kasutama alternatiivkütuseid tarbivaid veokeid. Elektri- ja vesinikukütusega veokite osas jäädi äraootavale seisukohale, sest tegemist on uute tehnoloogiatega ja ei ole teada, milliseks osutuvad nende veokite kasutamise kulud. Ettevõtted möönsid, et kui tehnoloogia areneb, siis võidakse minna üle uut tüüpi veokitele, aga see on kaugem tulevik. Kuigi keskkonnasäästlikkus on oluline, siis on ettevõtete jaoks tähtis, et uudseid veokeid oleks majanduslikult tasuv ja mugav kasutada.
Kütusekulude analüüsi tulemused näitasid, et 2021. aasta sügisel hakkas CNG hind järsult kallinema, kuid diislikütuse hind on samal ajal olnud stabiilsem. 2020. aasta kevadel toimus seoses aktsiisimäära langetamisega diislikütuse odavnemine, hiljem on selle hind siiski tõusnud. Selle tulemusena muutus CNG kasutamine võrreldes diislikütusega majanduslikult kulukamaks. Ettevõte jaoks, mis kasutas nii CNG kui diislikütusel töötavaid veokeid, tõi CNG hinna kasv kaasa kütusekulude olulise kasvu. Lõputöös uuritud ettevõttes kasvasid 2022. aasta CNG kulud võrreldes 2020. aastaga kuludega ligi kolmekordseks. Kokku on selles ettevõttes kütusekulu kasvanud sel perioodil rohkem kui 400 000 euro võrra.
Kütusekulude analüüsi tulemused näitasid, et CNG veokite kasutamine on majanduslikult soodsam, kui CNG kulu läbisõidu 1 km kohta on 0,04 euro võrra madalam. Põhjuseks on CNG veokite kõrgem maksumus ja suuremad hoolduskulud. Analüüsi tulemusena selgus, et CNG veokeid oli kasulikum kasutada 2020. a jaanuarist 2021. a oktoobrini. Alates 2021. a novembrist kuni 2023. a märtsini on soodsam olnud diiselveokite kasutamine.
Lõputöös uuriti piimavedusid teostava ettevõtte veoringe. Ettevõttel on 23 veoringi, millega veetakse piima 68 farmist kahte tehasesse. Farmid asuvad kokku 10 maakonnas, kuid peamiselt paiknevad need Kesk- ja Lõuna-Eestis. 20 veoringi teostatakse diiselveokitega ja kolmel veoringil kasutatakse CNG veokeid. Veoringi pikkus on seotud peale võetava piimakogusega. Suuremaid farme läbivad veoringidest osad võtavad piima peale vaid ühest farmist, mõnel ringil aga külastatakse kuni üheksat väiksemat farmi.
Kuna diiselveoki tankevälp on 1200–1500 km, siis on võimalik sellega sõita mitmeid järjestikuseid veoringe ilma tankimata. Kõige pikem veoring on 473 km, mis tähendab, et ka seda ringi saaks sõita vähemalt 2 korda enne kui on vaja tankida. CNG veokeid kasutatakse kuni 310 km pikkustel veoringidel ehk ka CNG veokiga saab neid ringe läbida ilma tankimata. Siiski oleks CNG veokeid parem kasutada, kui rajataks CNG tankla Imaveresse. Veoringidel, mille puhul kasutatakse CNG veokeid, soodustab seda Tartus asuv CNG tankla.
Veoringide analüüsi tulemused näitasid, et paljudel veoringidel on head võimalused CNG veokite kasutamiseks. Pooled veoringid on piisavalt lühikesed, et ei ole vaja CNG veokeid igal veoringil tankida. Ülejäänutes enamusel pikeneb marsruut vaid mõne kilomeetri võrra. Suur potentsiaal CNG veokite rakendamiseks on Võru ja Valgamaa veoringide puhul, mis on lühikesed ning CNG tankimine on võimaik Võrus asuva tehase läheduses.
Mitmeid veoringe uurides jõudis lõputöö autor järeldusele, et neid oleks võimalik lühendada, kui hakata toorpiima vedama teise tehasesse. Osadel juhtudel on sellega võimalik veoringe lühendada rohkem kui 100 km võrra ning ka ajaline võit on kohati 2 tundi ja rohkem. Veoringide muutmisel tuleb siiski arvestada tehaste tootmisvõimsuste tõttu ning seetõttu ei ole ilmselt alati kasulikum vedada piima lähemal asuvasse tehasesse.
Kokkuvõtvalt näitavad töö tulemused, et CNG veokite tankimine ei ole CNG veokite kasutuselevõtu juures väga suureks takistuseks. Pigem on probleemiks CNG kõrge hind koos CNG veokite endi kõrgema hinna ja suurema hoolduskuluga. Kui CNG hind langeks, siis oleks võimalik CNG veokeid praeguse Eesti CNG tanklavõrgu juures majanduslikult tasuvalt kasutada.The aim of the thesis was to evaluate the possibilities of using CNG trucks in road freight. In the thesis, two companies were studied, the first of which is engaged in food production, the second is a transport company. Both companies use diesel and CNG trucks
It turned out that at current CNG prices, CNG trucks have not proven to be economically efficient. CNG trucks are more expensive and have higher maintenance costs due to shorter service intervals. Due to the shorter refueling interval of CNG trucks and the lack of CNG filling stations in Estonia, the use of CNG trucks makes vehicle routing more difficult. The increase in the price of CNG has had an unfavorable effect on the use of CNG trucks and has led to an increase in the transport costs of companies. The companies that responded to the survey were not sure whether they would use alternative fuel trucks in the future. Although environmental sustainability is important for companies, the economic profitability of new trucks is also important. The results of the analysis of fuel costs showed that the use of CNG trucks is economically more favorable if the cost of CNG per 1 km is lower by 0.04 euros. It was more beneficial to use CNG trucks from January 2020 to October 2021. From November 2021 to March 2023 disel truck proved to be more economically efficient.
Milk transportation routes were analyzed in the thesis. The company has 23 trucks that transport milk from 68 farms to two factories. The results of the analysis of transport routes showed that many transport routes have good possibilities for using CNG trucks. Half of the routes are short enough that there is no need to refuel CNG trucks on every running. In most of the other cases, the route is only a few kilometers longer with CNG refueling. By studying several transport routes, the author of the thesis concluded that they could be shortened if raw milk were to be transported to another factory. In some cases, it is possible to shorten routes by more than 100 km, and the time gain is sometimes 2 hours or more.
In summary, the results of the work show that refueling CNG trucks is not a very big obstacle in the introduction of CNG trucks. Rather, the problem is the high price of CNG together with the higher price and higher maintenance cost of the CNG trucks themselves. If the price of CNG were to drop, it would be possible to economically use CNG trucks at the current Estonian CNG filling station network
CNG prospect’s as an alternative fuel in road transport in Poland
No full textW artykule omówione zostały uwarunkowania oraz perspektywy rozwoju CNG jako alternatywnego paliwa w transporcie samochodowym w Polsce. Zaprezentowano prawne i ekonomiczne uwarunkowania współczesnego wykorzystania CNG w transporcie samochodowym zarówno publicznym jak i prywatnym. Autor poddał analizie także kierunki i szanse rozwoju infrastruktury niezbędnej do wykorzystania CNG jako alternatywnego paliwa w transporcie samochodowym.Paper discussed the conditions and prospects of development of CNG as an alternative fuel in road transport in Poland. There was presented the legal and economic conditions of the modern use of CNG in road transport, both public and private. The author has analyzed trends and opportunities for the development of infrastructure necessary for the use of CNG as an alternative fuel in road transport
Reliability techniques to reduce the risk of failure in cng composite pressure vessel
No full textThis paper is devoted to present reliability techniques as a best failure mitigation tool for CNG composite pressure vessels. As far as composite materials are so sensitive to environmental working conditions, design methodology must be established based on reliability considerations. Because of over using of car fuel tanks, CNG should be properly substituted as an alternative fuel. Safety and cost are the most critical points in developing CNG-CPV to public usage. Meeting optimum point, design criteria must be followed by reliability criteria. In this paper, author tried to persuade CNG-CPV developer to take care of mentioned risks. Reliability testing is introduced as a feasible and reliable solution in order to assure desired safety
Pengaruh Temperatur Mesin Terhadap Kadar Emisi NOx pada Motor dengan Bahan Bakar Compressed Natural Gas (CNG)
No full textThe increase in NOx levels produced by CNG-fueled engines occurs when the fuel switches from gasoline to gas fuel (CNG). The author changed the otto 4 stroke gasoline engine, into a CNG-fueled motorbike and provided additional cooling in the form of a burst of air to the cylinder block. Changes in engine block temperature are detected using a temperature sensor placed on the engine oil. Bursts of air cooling result in temperature changes in engine oil. Changes in engine oil temperature are accompanied by changes in the resulting NOx emissions. This study shows that with a decrease in engine oil temperature in the combustion engine, NOx emission levels also decrease. From the research results it can be ignored that by providing additional air bursts will be able to reduce NOx emissions by up to 18
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