Existence of financial equilibria with restricted participation

We consider a two-date model of a financial exchange economy with finitely many agents having nonordered preferences and portfolio constraints. There is a market for physical commodities at any state today or tomorrow and financial transfers across time and across states are allowed by means of finitely many nominal assets or num´eraire assets. We prove a general existence result of equilibria for such a financial exchange economy in which portfolios are defined by linear constraints, extending the framework of linear equality constraints by Balasko et al. (1990), and the existence results in the unconstrained case by Cass (1984, 2006), Werner (1985), Duffie (1987), and Geanakoplos and Polemarchakis (1986). Our main result is a consequence of an auxiliary result, also of interest for itself, in which agents’ portfolio constraints are defined by general closed convex sets and the financial structure is assumed to satisfy a ”nonredundancy-type” assumption, weaker than the ones in Radner (1972) and Siconolfi (1989).Restricted participation, portfolio constraints, financial exchange economy, equilibrium, existence, arbitrage-free asset prices

Existence of financial equilibria with restricted participation

We consider a two-date model of a financial exchange economy with finitely many agents having nonordered preferences and portfolio constraints. There is a market for physical commodities at any state today or tomorrow and financial transfers across time and across states are allowed by means of finitely many nominal assets or numeraire assets. We prove a general existence result of equilibria for such a financial exchange economy in which portfolios are defined by linear constraints, extending the framework of linear equality constraints by Balasko et al. (1990) and the existence results in the unconstrained case by Cass (1984, 2006), Werner (1985), Duffie (1987) and Geanakoplos and Polemarchakis (1986). Our main result is a consequence of an auxiliary result, also of interest for itself, in which agents' portofolio constraints are defined by general closed convex sets and the financial structure is assumed to satisfy a "nonredundancy-type" assumption, weaker than the ones in Radner (1972) and Siconolfi (1989).Restricted participation; portfolio constraints; financial exchange economy; equilibrium; existence; arbitrage-free asset prices

Rolling Optimization Method for Humanoid Robots

In this paper, a method of optimizing the rolling amplitude needed for a stable and smooth walking movement of a humanoid robot is considered. The optimization algorithm was based on minimizing a cost function defined by the rolling overshoot. The amplitude of the rolling during locomotion was calculated using the lateral zero moment point (ZMP) position. The initial value of the rolling was the static rolling that corresponds to the position of the ZMP at the center of the support polygon. The algorithm consisted of performing a ZMP calculation at two points that correspond to single support phases. Simplifying the robot as an inverted pendulum, the gyro feedback controller parameters were tuned to have a passive-like walking motion and a faster response of the robot state to the equilibrium point at single support phase. Experimental results, using HOAP-3 of Fujitsu, showed that the algorithm was successfully implemented along with the locomotion controller. With the optimal rolling technique, the humanoid robot could exhibit a stable and smooth walking movement

Channel Estimation Study for Block - Pilot Insertion in OFDM Systems under Slowly Time Varying Conditions

In this paper, we propose a study of performance of the channel estimation using LS, MMSE, LMMSE and Lr-LMMSE algorithms in OFDM (Orthogonal Frequency Division Multiplexing) system which, as known suffers from the time variation of the channel under high mobility conditions, using block pilot insertion. The loss of sub channel orthogonality leads to inter-carrier interference (ICI). Using many algorithms for channel estimation, we will show that, for a 16- QAM modulation, the LMMSE algorithm performs well to achieve this estimation but when the SNR (Signal Noise Rate) is high, the four algorithms (LS, MMSE, LMMSE and Lr-LMMSE) perform similarly, this is not always the case for another scheme of modulation. We will improve also the mean squared error for these algorithms. It will be illustrious in this paper that the LMMSE algorithm performs well with the block- pilot insertion as well as its low rank version which behave very good even when the size of FFT is very high.Comment: 16 pages, 10 figures; International Journal of Computer Networks & Communications (IJCNC) Vol.3, No.6, November 2011, 39-5

Financial Economies With Restricted Participation

An abundant literature is concerned with the existence of equilibrium in incomplete markets where participation to financial markets is not restricted. To mention a few, Cass (1984), Werner (1985), Geanakoplos and Polemarchakis (1986), Duffie (1987), Duffie and Shafer (1985) and Magill and Quinzii (1996). Financial economies with incomplete markets assume (in general) a symmetric participation structure, i.e. each consumer is confronted with the same restrictions on her portfolio trades. This is a very limiting assumption: in reality, people get to know about different investment opportunities and not all investors are able to trade in the same markets. In this work we consider institutional restrictions on trading activity in the financial markets. Following Siconolfi (1989), Angeloni and Cornet (2006), and Hahn and Won (2007), the broadest formulation of such restricted participation is to assume that households face financial constraints modeled by closed convex subsets of the portfolio space. Our contribution to the literature on general equilibrium of financial markets is threefold. In Chapter 2 we refine the definition of reduced financial structure to accommodate the case of financial structures with restricted participation. We then provide a characterization of reduced financial structures in terms of arbitrage-free prices and by the compactness of a set of ``admissible'' portfolio allocations. In Chapter 3 we introduce an equivalence relation on the set of financial structures and we show that, under mild assumptions, every financial structure is equivalent to a reduced financial structure, and that subsequently, all equilibria in a financial economy are in one-to-one correspondence with the equilibria of an economy where the financial structure is replaced by an equivalent reduced one. Finally, in Chapter 4 we prove a general existence result of equilibria for financial exchange economies with restricted participation in which agents may have nonordered preferences. Our result extends the results by Radner (1972), and Siconolfi (1989), and also extends to the restricted participation case the results by Cass (1984), Werner (1985), and Duffie (1987)

Designing Well-Organized Donor-Bridge-Acceptor Conjugated Systems Based on Cyclopentadithiophene as Donors in Bulk Heterojunction Organic Solar Cells: DFT-Based Modeling and Calculations

Two host materials based on CPDT as donors in bulk heterojunction organic solar cells were designed and investigated by means of DFT calculations. The first one (P-CPDTBT3) is a copolymer with D-A configuration and the second one (SM-CPDTDPP) is a D-π-A-π-D type small molecule. The investigated materials exhibited interesting structural properties with high planarity and rigidity originated from intra-molecular non-covalent interactions between the different building blocks. Thanks to their narrow band gaps, the optical absorption spectra have covered the main part of solar spectrum of interest. In addition, some general transport properties have been established. The transition density matrix (TDM) was used to get insight into the interaction of hole–electron localization and the electronic excitation processes. The photovoltaic parameters (FF, Voc) were calculated. The obtained results have been attempted to provide novel structure–property relationships for the rational design strategies of high-performance photovoltaic materials with power conversion efficiency of nearly 10%

Computational Study on Optoelectronic Properties of Donor-Acceptor Type Small π-Conjugated Molecules for Organic Light-Emitting Diodes (OLEDs) and Nonlinear Optical (NLO) Applications

Recently, donor-acceptor type molecule that contains electron-rich (D) and electron-deficient (A) moiety has emerged as an interesting approach of molecular design strategy to develop organic light-emitting diodes (OLEDs) and non-linear optical (NLO) devices. In this work, we report a theoretical investigation based on two donor-acceptor (D-A) type small π-conjugated molecules based on dithieno [3,2-b: 2′,3′-d] pyrrole (DTP) and anthracene derivatives. All of the theoretical calculations were performed by Density Functional Theory (DFT) approach at B3LYP/6-31 g(d) level of theory. The structural, electronic, optical and charge transfer properties were investigated. The effect of acceptor blocks (DPA and DTA) on the molecular characteristics was elucidated. The obtained results clearly show that the studied compounds exhibit non-coplanar structures with low electronic band gap values. These relevant structures exhibited important optical absorption and intense emission in the green-yellow region. NLO investigation based on static polarizability (α0), first-order hyperpolarizability (β0) and second-order hyperpolazabilty (ɣ0) demonstrated that the studied materials exhibit excellent NLO properties. Thus, the designed materials showed promising capabilities to be utilized in OLED and NLO applications