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Search Results: 1 - 10 of 198238 matches for " N. Adamovic "
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Guidelines for Optimization of the Absorber Layer Energy Gap for High Efficiency Cu(In,Ga)Se2 Solar Cells  [PDF]
N. Severino, N. Bednar, N. Adamovic
Journal of Materials Science and Chemical Engineering (MSCE) , 2018, DOI: 10.4236/msce.2018.64015
Abstract: This work investigates in-depth the effects of variation of the compositional ratio of the absorber layer in Cu(In,Ga)Se2 (CIGS) thin-film solar cells. Electrical simulations were carried out in order to propose the most suitable gallium double-grading profile for the high efficiency devices. To keep the model as close as possible to the real behavior of the thin film solar cell a trap model was implemented to describe the bulk defects in the absorber layer. The performance of a solar cell with a standard CIGS layer thickness (2 μm) exhibits a strong dependence on the front grading height (decreasing band gap toward the middle of the CIGS layer). An absolute gain in the efficiency (higher than 1%) is observed by a front grading height of 0.22. Moreover, simulation results show that the position of the plateau (the region characterized by the minimum band gap) should be accurately positioned at a compositional ratio of 20% Ga and 80% In, which corresponds to the region where a lower bulk defect density is expected. The developed model demonstrates that the length of the plateau is not playing a relevant role, causing just a slight change in the solar cell performances. Devices with different absorber layer thicknesses were simulated. The highest efficiency is obtained for a CIGS thin film with thicknesses between 0.8 and 1.1 μm.
A construction of admissible $A_1^{(1)}$-modules of level $-{4/3}$
Drazen Adamovic
Mathematics , 2004,
Abstract: By using generalized vertex algebras associated to rational lattices, we construct explicitly the admissible modules for the affine Lie algebra $A_1 ^{(1)}$ of level $-{4/3}$. As an application, we show that the W(2,5) algebra with central charge c=-7 investigated in math.QA/0207155 is a subalgebra of the simple affine vertex operator algebra $L(-{4/3}\Lambda_0)$.
Lie superalgebras and irreducibility of A_1^(1)-modules at the critical level
Drazen Adamovic
Mathematics , 2006, DOI: 10.1007/s00220-006-0153-7
Abstract: We introduce the infinite-dimensional Lie superalgebra ${\mathcal A}$ and construct a family of mappings from certain category of ${\mathcal A}$-modules to the category of A_1^(1)-modules of critical level. Using this approach, we prove the irreducibility of a family of A_1^(1)-modules at the critical level. As a consequence, we present a new proof of irreducibility of certain Wakimoto modules. We also give a natural realizations of irreducible quotients of relaxed Verma modules and calculate characters of these representations.
A realization of certain modules for the $N=4$ superconformal algebra and the affine Lie algebra $A_2 ^{(1)}$
Drazen Adamovic
Mathematics , 2014,
Abstract: We shall first present an explicit realization of the simple $N=4$ superconformal vertex algebra $L_{c} ^{N=4}$ with central charge $c=-9$. This vertex superalgebra is realized inside of the $ b c \beta \gamma $ system and contains a subalgebra isomorphic to the simple affine vertex algebra $L_{A_1} (- \tfrac{3}{2} \Lambda_0)$. Then we construct a functor from the category of $L_{c} ^{N=4}$--modules with $c=-9$ to the category of modules for the admissible affine vertex algebra $L_{A_{2} } (-\tfrac{3}{2} \Lambda_0)$. By using this construction we construct a family of weight and logarithmic modules for $L_{c} ^{N=4}$ and $L_{A_{2} } (-\tfrac{3}{2} \Lambda_0)$. We also show that a coset subalgebra of $L_{A_{2} } (-\tfrac{3}{2} \Lambda_0)$ is an logarithmic extension of the $W(2,3)$--algebra with $c=-10$. We discuss some generalizations of our construction based on the extension of affine vertex algebra $L_{A_1} (k \Lambda_0)$ such that $k+2 = 1/p$ and $p$ is a positive integer.
Representations of N=2 superconformal vertex algebra
Drazen Adamovic
Mathematics , 1998,
Abstract: Let $L_c$ be simple vertex operator superalgebra(SVOA) associated to the vacuum representation of N=2 superconformal algebra with the central charge $c$. Let $c_m = {3m}/{m+2}$. We classify all irreducible modules for the SVOA $L_{c_m}$. When $m$ is an integer we prove that the set of all unitary representations of N=2 superconformal algebra with the central charge $c_m$ provides all irreducible $L_{c_m}$-modules. When $m \notin {\N} $ and $m$ is an admissible rational number we show that irreducible $L_{c_m}$-modules are parameterized with the union of one finite set and union of finitely many rational curves.
Classification of irreducible modules of certain subalgebras of free boson vertex algebra
Drazen Adamovic
Mathematics , 2002,
Abstract: Let M(1) be the vertex algebra for a single free boson. We classify irreducible modules of certain vertex subalgebras of M(1) generated by two generators. These subalgebras correspond to the W(2, 2p-1)--algebras with central charge $1- 6 \frac{(p - 1) ^{2}}{p}$ where p is a positive integer, $p \ge 2$. We also determine the associated Zhu's algebras.
Regularity of certain vertex operator algebras with two generators
Drazen Adamovic
Mathematics , 2001,
Abstract: For every $m \in {\C} \setminus \{0, -2\}$ and every nonnegative integer $k$ we define the vertex operator (super)algebra $D_{m,k}$ having two generators and rank $ \frac{3 m}{m + 2}$. If $m$ is a positive integer then $D_{m,k}$ can be realized as a subalgebra of a lattice vertex algebra. In this case, we prove that $D_{m,k}$ is a regular vertex operator (super)algebra and find the number of inequivalent irreducible modules.
A classification of irreducible Wakimoto modules for the affine Lie algebra $A_1 ^{(1)}$
Drazen Adamovic
Mathematics , 2014,
Abstract: By using methods developed in arXiv:math/0602181 we study the irreducibility of certain Wakimoto modules for $\widehat{sl_2}$ at the critical level. We classify all $\chi \in {\Bbb C}((z))$ such that the corresponding Wakimoto module $W_{\chi}$ is irreducible. It turns out that zeros of Schur polynomials play important rule in the classification result.
Some Rational Vertex Algebras
Drazen Adamovic
Mathematics , 1995,
Abstract: Let $L((n-\tfrac 3 2)\Lambda_0)$, $n \in \Bbb N$, be a vertex operator algebra associated to the irreducible highest weight module $L((n-\tfrac 3 2)\Lambda_0)$ for a symplectic affine Lie algebra. We find a complete set of irreducible modules for $L((n-\tfrac 3 2)\Lambda_0)$ and show that every module for $L((n-\tfrac 3 2)\Lambda_0)$ from the category $\Cal O$ is completely reducible.
A construction of some ideals in affine vertex algebras
Drazen Adamovic
Mathematics , 2001,
Abstract: Let $N_{k} (\g)$ be a vertex operator algebra (VOA) associated to the generalized Verma module for affine Lie algebra of type $A_{\ell -1} ^{(1)}$ or $C_{\ell} ^{(1)}$. We construct a family of ideals $J_{m,n} (\g)$ in $N_{k} (\g)$, and a family $V_{m,n} (\g)$ of quotient VOAs. These families include VOAs associated to the integrable representations, and VOAs associated to admissible representations at half-integer levels investigated in q-alg/9502015. We also explicitly identify the Zhu's algebras $A(V_{m,n} (\g))$ and find a connection between these Zhu's algebras and Weyl algebras.
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