A note on the determinant of a functional confluent vandermonde matrix and controllability

AbstractA factorization expression for the determinant of the confluent Vandermonde matrix is extended to a functional form. With the exponential function, simpler necessary and sufficient conditions for controllability of sampled input systems follow

Optimal household energy management and participation in ancillary services with PV production

The work presented in this paper deals with a project aiming to increase the value of photovoltaic (PV) solar production for residential application. To contribute to the development of the new functionalities for such system and the efficient control system to optimize its operation, this paper defines the possibility for the proposed system to participate to the ancillary services, particularly in active power service provider. This service of PV-based system for housing application, as it does not exist today, has led to a market design proposition in the distribution system. The mathematical model for calculating the optimal operation of system (sources, load, and the exchange power with the grid) results in a linear mix integer optimization problem where the objective is to maximize the profit obtained by participating to electricity market. The approach is illustrated in an example study case. The PV producer could benefit from its intervention on balancing market or ancillary services market despite of the impact on the profit of several kinds of uncertainty, as the intermittence of PV source.energy management ; ancillary services ; PV production ; household application

Rural Roads: Multi-Tier Monitoring of Infrastructure: Top Down and Bottom Up

The focus of this paper is on the last set of these questions -- that of the capacity and the practice of decentralized infrastructure monitoring. The experience and practice of low, middle and high income countries alike is considered. The paper is organized as follows: the next section, Section 2, defines how infrastructure is defined for purposes here, and then proceeds to discuss where the monitoring of infrastructure fits into the broader activity of decentralized infrastructure management. Section 3 then lays out some of the “pre-conditions” for effective decentralized monitoring of infrastructure, leading to the conclusion that for many developing countries these pre-conditions are not satisfied and, thus, why in order to make useful statements about decentralized monitoring of infrastructure one turns to specific case studies for lessons learned from current practice. Accordingly, Section 4 focuses on a mix of illustrative country practices on governmental monitoring of infrastructure that serve to reinforce the conventional view that though there are core lessons common to all intergovernmental societies, there is no single “best” approach since each country faces different starting and end points to which they aspire. Section 5 reviews selected non-governmental and civil society role in what the paper labels as decentralized “bottom up” monitoring. Concluding comments are provided in Section 6

Assessment of cattle marketing in Ea Kar district, Daklak, Vietnam in 2008

This paper describes and discusses the results of a Cattle Market Study conducted in Ea Kar district, Daklak province of Vietnam in 2008. Since 2000, CIAT, TNU and NIAH, in partnership with the Ea Kar Extension Service and District Government, have worked in Ea Kar to introduce the concept of cultivating forage grasses and legumes on farmers’ land for improved smallholder beef cattle production. By 2007, more than 2400 smallholder farmers had adopted cultivated forages to feed to their animals. This new feed resource has enabled farmers to change their cattle production system. They have intensified their production systems from grazing to pen-fed cattle using planted forages as the main feed for fattening, and by changing from local breeds to raising Laisind and cross-bred cattle

Optimal household energy management and economic analysis: from sizing to operation scheduling

The study presented in this paper takes part in a project aiming to increase the value of solar production for residential application with a medium-term vision where preferential solar energy subsidies will decrease before to disappear. This study is dedicated to propose and develop optimal energy architecture at supply side, a multi-source system based on photovoltaic (PV) solar energy connecting to main electrical network, taking further into account the effectiveness of intelligent demand side management. To investigate this issue, a method of optimal supplying system sizing and household energy management has been developed. This method, which has been formulated employing Mix Integer Linear Programming (MILP), enables the calculation of the appropriate configuration for power supply system and the optimal operation control to be applied. Using a Net Present Value (NPV) and Probability Index (P.I) basis, the economic analysis allows estimation of the viability of the proposed system under different factors of influence such as renewable energy policies, technology evolutions leading to cheaper installed PV module cost and deregulated electricity market. Simulation results show that, the solution makes it possible for PV power to be significantly valued by the customers without subsidized measures.connected-grid PV system ; battery storage ; sizing optimization ; energy management ; MILP

Counterion Condensation and Fluctuation-Induced Attraction

We consider an overall neutral system consisting of two similarly charged plates and their oppositely charged counterions and analyze the electrostatic interaction between the two surfaces beyond the mean-field Poisson-Boltzmann approximation. Our physical picture is based on the fluctuation-driven counterion condensation model, in which a fraction of the counterions is allowed to ``condense'' onto the charged plates. In addition, an expression for the pressure is derived, which includes fluctuation contributions of the whole system. We find that for sufficiently high surface charges, the distance at which the attraction, arising from charge fluctuations, starts to dominate can be large compared to the Gouy-Chapmann length. We also demonstrate that depending on the valency, the system may exhibit a novel first-order binding transition at short distances.Comment: 15 pages, 8 figures, to appear in PR

Caretaker mental health and family environment factors are associated with adolescent psychiatric problems in a Vietnamese sample

Little is known about risk factors for adolescent mental health in Vietnam. The present study investigated the relationship between caretaker mental health and adolescent mental health in a cross-sectional Vietnamese sample. Primary caretakers completed measures of their own mental distress and general health status using the Self-Reporting Questionnaire-20 (SRQ-20) as well as reports of adolescent mental health using the parent version of the Strengths and Difficulties Questionnaire (SDQ). Multivariate regression models were used to examine the relationships between the caretaker and adolescent health variables. The demographic factors of age, sex, ethnicity, religious affiliation, and household wealth status demonstrated significant relationships with SDQ subscale scores. Caretaker mental health was positively associated with adolescent mental health, and this association remained significant even after accounting for other relevant demographic variables and caretaker general health status. Understanding correlates of adolescent mental health difficulties may help identify youth and families at risk for developing psychiatric problems and inform mental health interventions in Vietnam

The Persistence Length of a Strongly Charged, Rod-like, Polyelectrolyte in the Presence of Salt

The persistence length of a single, intrinsically rigid polyelectrolyte chain, above the Manning condensation threshold is investigated theoretically in presence of added salt. Using a loop expansion method, the partition function is consistently calculated, taking into account corrections to mean-field theory. Within a mean-field approximation, the well-known results of Odijk, Skolnick and Fixman are reproduced. Beyond mean-field, it is found that density correlations between counterions and thermal fluctuations reduce the stiffness of the chain, indicating an effective attraction between monomers for highly charged chains and multivalent counterions. This attraction results in a possible mechanical instability (collapse), alluding to the phenomenon of DNA condensation. In addition, we find that more counterions condense on slightly bent conformations of the chain than predicted by the Manning model for the case of an infinite cylinder. Finally, our results are compared with previous models and experiments.Comment: 13 pages, 2 ps figure

Effectiveness of cervical pessary compared to cervical cerclage with or without vaginal progesterone for the prevention of preterm birth in women with twin pregnancies and a short cervix : Study protocol for a two-by-two factorial randomised clinical trial

Peer reviewedPublisher PD