549 research outputs found
The relevance of index funds for pension investment in equities
No full textThe rise of index funds over the past 25 years has been a remarkable phenomenon. The traditional rationale for the success of index funds is market efficiency, net of transaction costs. The authors also focus on the role of agency conflicts between fund managers and investors, which are hard to resolve, given the low power of statistical tests of performance. Most of the empirical evidence about the superiority of index funds comes from the United States. The authors discuss issues associated with the application of index funds in developing countries, as well as policy issues in the financial sector that affect the enabling market infrastructure for index funds. They also apply these ideas to thinking about the relevance of index funds for pension investment. The equity premium provides powerful motivation for equity investment by pension funds. Index funds make it possible to sidestep the complexities of forming contracts and monitoring institutions to govern fund managers. In developing countries that seek to use index funds in pension investment, there are avenues through which policymakers can make index funds more viable. In many countries there are significant avenues for improving construction of the market index as well as market mechanisms used in the equity market.Agricultural Knowledge&Information Systems,Payment Systems&Infrastructure,Economic Theory&Research,Markets and Market Access,Access to Markets
Preparation, characterization and properties of novel PSMA-POSS systems by reactive blending
No full textNovel hybrid systems based on styrene-maleic anhydride copolymers (PSMA) and a
polyhedral oligomeric silsesquioxane characterized by an amino group as reactive side (POSS-NH2) have
been synthesized by one-step reactive blending. The features of the above materials were compared with those
of systems based on polystyrene (PS) or an unreactive POSS in order to highlight the effect of both the
reactivity of the silsesquioxane and the polymer matrix functionality on the material final characteristics.
FTIR measurements evidenced the occurrence of imidization reaction between theMAgroup of PSMA and
the amino group of POSS molecule, with the consequent formation of a cyclic imide linkage binding POSS to
the polymer backbone. This reaction turned out to promote POSS distribution in the polymer matrix, as only
the systems characterized by the aforementioned functionalities allowed to obtain a silsesquioxane dispersion
at nanometric level. By following the evolution of the system features, in terms of glass transition temperature
(Tg), morphology, yield, and crystallinity, with the mixing time, it has been verified that using a Tmix lower
than POSS melting temperature, a surface reaction at the POSS crystal/polymer boundary occurs, leading to
the formation of a very peculiar two-phase structure evolving with time. The two phases have been found to
contain different POSS concentrations. Biphasic systems, studied by means of differential scanning
calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA), have showed two Tg, depending
on the presence of unbound POSS acting as a plasticizer. Films prepared from the systems PSMA-POSS
containing low amounts of silsesquioxane (up to 10 wt %) have been found to be completely transparent,
while the transparency of those based on higher POSS content has been achieved only after removing the
unbound POSS. Indeed, the role of silsesquioxane on surface properties has been assessed by evaluating film
wettability
Preparation, Characterization, and Properties of Novel PSMA−POSS Systems by Reactive Blending
No full textNovel hybrid systems based on styrene−maleic anhydride copolymers (PSMA) and a polyhedral oligomeric silsesquioxane characterized by an amino group as reactive side (POSS-NH2) have been synthesized by one-step reactive blending. The features of the above materials were compared with those of systems based on polystyrene (PS) or an unreactive POSS in order to highlight the effect of both the reactivity of the silsesquioxane and the polymer matrix functionality on the material final characteristics. FTIR measurements evidenced the occurrence of imidization reaction between the MA group of PSMA and the amino group of POSS molecule, with the consequent formation of a cyclic imide linkage binding POSS to the polymer backbone. This reaction turned out to promote POSS distribution in the polymer matrix, as only the systems characterized by the aforementioned functionalities allowed to obtain a silsesquioxane dispersion at nanometric level. By following the evolution of the system features, in terms of glass transition temperature (Tg), morphology, yield, and crystallinity, with the mixing time, it has been verified that using a Tmix lower than POSS melting temperature, a surface reaction at the POSS crystal/polymer boundary occurs, leading to the formation of a very peculiar two-phase structure evolving with time. The two phases have been found to contain different POSS concentrations. Biphasic systems, studied by means of differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA), have showed two Tg, depending on the presence of unbound POSS acting as a plasticizer. Films prepared from the systems PSMA−POSS containing low amounts of silsesquioxane (up to 10 wt %) have been found to be completely transparent, while the transparency of those based on higher POSS content has been achieved only after removing the unbound POSS. Indeed, the role of silsesquioxane on surface properties has been assessed by evaluating film wettability
Nuclear interactions in the P<SUB>1/2</SUB>-g<SUB>9/2</SUB> configurations
No full textZr90 offers a very good case for the study of T=1 levels in the p1/2-g9/2 subshells and has recently been explored by several authros. Here earlier calculations of Thankappan and Waghmare are extended and analysed in detail. It is found that a simple central two-body interaction can be constructed which will give correctly the energy levels of the (g9/2)2 configuration, and hence also the levels of a (g9/2)n configuration. However, the same interaction fails to give correctly the levels of the other configurations (p1/2)(g9/2) and (p1/2)2. This simple two-body nuclear interaction is thus shown to be configuration dependent. It is pointed out that experimental identification of the as yet unobserved 4- level would be very helpful for further elucidation of this phenomenon. The results are compared with those of the other authors
Rank Exponent Method Based Optimal Control of AGC for Two-Area Interconnected Power Systems
No full textAutomatic generation control (AGC) is employed in power systems to maintain balance between generation and load by adjusting output of generators in real time. Controller continuously monitors system frequency and tie-line power flow by responding to fluctuations in electricity demand and supply and optimizes generator dispatch, reduces power imbalances, and enhances grid stability. This work proposes and solves the issues of the AGC in two-area interconnected power systems by proposing a new approach based on both Jaya algorithm and the rank exponent method. In particular, we design a proportional-integral-derivative controller with derivative filtering (PIDm), where the effect of the noise is mitigated by the use of a filter with derivative gain. We propose to build the objective function, to tune the controller's parameters, as the linear combination of three sub-objectives, namely integral of time multiplied absolute error (ITAE) for frequency deviations, tie-line power deviation, and area-control errors (ACEs). The rank method is exploited to evaluate the weights of these sub-objectives, while the final overall objective function is minimized exploiting the Jaya algorithm. The proposed controller's performance is assessed in six different scenarios with load disturbances, and its effectiveness is compared to state-of-art controllers tuned using salp swarm algorithm (SSA), Nelder-Mead simplex (NMS), symbiotic organisms search (SOS), elephant herding optimization (EHO), and Luus-Jaakola (LJ) optimization algorithms. To illustrate the frequency and tie-line power changes, results are also shown, and a statistical study is finally carried out to evaluate the recommended controller's overall effectiveness. Additionally, Friedman rank test as no-parametric statistical analysis is also done in order to evaluate the significance level of optimization algorithms. Our numerical findings evidence that the proposed PIDm controller outperforms other existing optimization-based controllers in terms of performance and utility, thus proving to be very effective for handling AGC issues in two-are interconnected power systems
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