Spinors for Spinning p-Branes

The group of the p-brane world volume preserving diffeomorphism is considered. The infinite-dimensional spinors of this group are related, by the nonlinear realization techniques, to the corresponding spinors of its linear subgroup, that are constructed explicitly. An algebraic construction of the Virasoro and Neveu-Schwarz-Ramond algebras, based on this infinite-dimensional spinors and tensors, is demonstrated.Comment: 18 page

World Spinors - Construction and Some Applications

The existence of a topological double-covering for the $GL(n,R)$ and diffeomorphism groups is reviewed. These groups do not have finite-dimensional faithful representations. An explicit construction and the classification of all $\bar{SL}(n,R)$, $n=3,4$ unitary irreducible representations is presented. Infinite-component spinorial and tensorial $\bar{SL}(4,R)$ fields, "manifields", are introduced. Particle content of the ladder manifields, as given by the $\bar{SL}(3,R)$ "little" group is determined. The manifields are lifted to the corresponding world spinorial and tensorial manifields by making use of generalized infinite-component frame fields. World manifields transform w.r.t. corresponding $\bar{Diff}(4,R)$ representations, that are constructed explicitly.Comment: 19 pages, Te

Minimal Algebras for Relativistic Wave Equations

The idea that matrices occuring in both first and second order relativistic wave equations generate (under commutation) some finite Lie algebra, which contains the Lorentz algebra, is considered. For first and second order wave equations the minimal non trivial Lie algebras are so(3,2) and sl(4,R) respectively. The unique mass condition and the so(3,2) algebra rule out all but the Dirac and Duffin-Kemmer equations, while the sl(4,R) algebra is associated to the Klein-Gordon, Proca and Joos-Weinberg (spin 1) equations

Probability of failure of thermal power plant boiler tubing system due to corrosion

Korozija predstavlja nepovratni proces degradacije materijala. Zbog nepovoljanog uticaja koji ima na radne osobine materijal, posebno materijala cevnog sistema kotla, ona predstavlja predstavlja neizostavni deo rada termoenergetskih postrojenja i glavni uzrok mnogih otkaza. Pored uobičajenih metoda za procenu preostalog radnog veka korisno je primeniti i metode za procenu pouzdanosti kotlovskih cevi termoenergetskih postrojenja koje su oštećene korozijom. Korelacijom rezultata koji se dobijaju primenom ove dve različite metode moguće je dobiti bolja saznanja o trenutnom stanju materijala cevi uz istovremeno izvođenje tačnije procene njihovog ponašanja tokom dalje eksploatacije. Stoga je u ovom radu na primeru cevi ulazne zone paketa naknadnog pregrejača prikazan integralni pristup procene preostalog radnog veka i pouzdanosti. Razmatranja ove vrste su veoma značajna za pristupe u održavanju koji su zasnovani na riziku.Corrosion is irreversible process of material degradation. Due to detrimental effects exerted on the operating material characteristics, especially in the boiler tube system, it is of one the most important issues in the operation of thermal plants and is considered to be the root cause of many outages. Besides common remaining life assessment methods, it is useful to apply a method of reliability evaluation of the thermal power plant boiler tubes with corrosion damages. Correlation of results obtained by these two methods makes possible to obtain a better knowledge of current tubes material state as well as a more accurate assessment of their behavior during future exploitation. Therefore, an integrated approach of remaining life assessment and reliability evaluation, on the first stage reheater tubes system example, is presented in this paper. Considerations of this kind are very important for the risk-based maintenance programs

Probability of failure of thermal power plant boiler tubing system due to corrosion

Korozija predstavlja nepovratni proces degradacije materijala. Zbog nepovoljanog uticaja koji ima na radne osobine materijal, posebno materijala cevnog sistema kotla, ona predstavlja predstavlja neizostavni deo rada termoenergetskih postrojenja i glavni uzrok mnogih otkaza. Pored uobičajenih metoda za procenu preostalog radnog veka korisno je primeniti i metode za procenu pouzdanosti kotlovskih cevi termoenergetskih postrojenja koje su oštećene korozijom. Korelacijom rezultata koji se dobijaju primenom ove dve različite metode moguće je dobiti bolja saznanja o trenutnom stanju materijala cevi uz istovremeno izvođenje tačnije procene njihovog ponašanja tokom dalje eksploatacije. Stoga je u ovom radu na primeru cevi ulazne zone paketa naknadnog pregrejača prikazan integralni pristup procene preostalog radnog veka i pouzdanosti. Razmatranja ove vrste su veoma značajna za pristupe u održavanju koji su zasnovani na riziku.Corrosion is irreversible process of material degradation. Due to detrimental effects exerted on the operating material characteristics, especially in the boiler tube system, it is of one the most important issues in the operation of thermal plants and is considered to be the root cause of many outages. Besides common remaining life assessment methods, it is useful to apply a method of reliability evaluation of the thermal power plant boiler tubes with corrosion damages. Correlation of results obtained by these two methods makes possible to obtain a better knowledge of current tubes material state as well as a more accurate assessment of their behavior during future exploitation. Therefore, an integrated approach of remaining life assessment and reliability evaluation, on the first stage reheater tubes system example, is presented in this paper. Considerations of this kind are very important for the risk-based maintenance programs

Research of injuries of passengers in city buses as a consequence of non-collision effects

In this study, a research of injuries of passengers in city buses is presented, which are not a consequence of collision of buses with other objects. The number of injured passengers in the territory of Belgrade was registered, during three consecutive years. Most frequently injured body part was the head, while women over the age of 60 are the most vulnerable population of passengers. The most often reason for the appearance of injuries was the effect of acceleration. Also, it is pointed out to the importance of consideration of the problem of multiple injuries. These injuries are more complex than the individual ones, and they may indicate to the existence of greater omissions in the design of the interior of the bus. Proposals for certain system solutions, as well as some recommendations for designing are given, which can improve the safety of passengers who use the city bus as a means of transportation

Numerical simulation of quenching process, part II: Residual stresses

Polazeći od osnovnih zakona mehanike kontinuuma, definisana je procedura primene metode konačnih elemenata na problem određivanja zaostalih napona usled kaljenja, pri čemu su kao ulazna veličina korišćena vremenska i prostorna raspodela temperature, dobijena u prvom delu rada. Kao primena opisane procedure analizirana su dva primera određivanja zaostalih napona usled kaljenja cilindra od čelika, u jednom slučaju bez faznih transformacija a u drugom slučaju uzimajući u obzir i fazne transformacije tipa austenit beinit.Starting from the basic laws of continuum mechanics, the procedure of finite element method application to the quenching residual stresses evaluation is defined, taking as input data spatial and time distribution of temperature obtained in the first part of paper. As an application of this procedure two examples of calculation of residual stresses due to cylinder quenching are given, in one case without phase transformation, and in the other one with phase transformation of austenite - bainite type

Numerical simulation of quenching process, part II: Residual stresses

Polazeći od osnovnih zakona mehanike kontinuuma, definisana je procedura primene metode konačnih elemenata na problem određivanja zaostalih napona usled kaljenja, pri čemu su kao ulazna veličina korišćena vremenska i prostorna raspodela temperature, dobijena u prvom delu rada. Kao primena opisane procedure analizirana su dva primera određivanja zaostalih napona usled kaljenja cilindra od čelika, u jednom slučaju bez faznih transformacija a u drugom slučaju uzimajući u obzir i fazne transformacije tipa austenit beinit.Starting from the basic laws of continuum mechanics, the procedure of finite element method application to the quenching residual stresses evaluation is defined, taking as input data spatial and time distribution of temperature obtained in the first part of paper. As an application of this procedure two examples of calculation of residual stresses due to cylinder quenching are given, in one case without phase transformation, and in the other one with phase transformation of austenite - bainite type