Transmission cost allocation by cooperative games and coalition formation

The allocation of costs of a transmission system to its users is still a pending problem in many electric sector market regulations. This paper contributes with a new allocation method among the electric market participants. Both cooperation and competition are defined as the leading principles to fair solutions and efficient cost allocation. The method is based mainly on the responsibility of the agents in the physical and economic use of the network, their rational behavior, the formation of coalitions, and cooperative game theory resolution mechanisms. The designed method is applicable to existing networks or to their expansion. Simulations are made with sample networks. Results conclude that adequate solutions are possible in a decentralized environment with open access to networks. Comparisons with traditional allocation systems are shown and cooperative game solutions compare better in economic and physical terms.     

Lipid peroxidation and antioxidant status in adults receiving lipid-based home parenteral nutrition

BACKGROUND: Infusion of lipid emulsions rich in polyunsaturated fatty acids (PUFAs) may increase lipid peroxidation, which is counteracted mainly by superoxide dismutase (SOD) (a zinc-, copper-, and manganese-dependent enzyme), selenium-dependent glutathione peroxidase (Se-GSHPx), and alpha-tocopherol. OBJECTIVE: We investigated lipid peroxidation and antioxidant status in patients receiving home parenteral nutrition (HPN) providing variable amounts of a lipid emulsion rich in PUFAs, and alpha-tocopherol, zinc, copper, and manganese as recommended by the American Medical Association, and no selenium. DESIGN: Serum malondialdehyde, plasma alpha-tocopherol, selenium, Se-GSHPx, PUFAs, and red blood cell Se-GSHPx and SOD were evaluated in 12 patients and in 25 healthy control subjects. Malondialdehyde was also assessed in a group of 40 healthy control subjects. RESULTS: Patients had significantly higher concentrations of malondialdehyde and SOD and lower alpha-tocopherol concentrations and selenium nutritional status. Linear regression analysis showed that malondialdehyde was associated with the daily PUFA load (r=0.69, P< 0.03) and with plasma alpha-tocopherol (r=-0.59, P< 0.05), but stepwise multiple regression analysis confirmed only the association between malondialdehyde and alpha-tocopherol; plasma alpha-tocopherol was associated with the daily PUFA load (r=-0.65, P< 0.04) and with the duration of HPN (r=-0.74, P< 0.02). CONCLUSIONS: In HPN patients, the peroxidative stress due to lipid emulsions rich in PUFAs is counteracted primarily by alpha-tocopherol. The dosages of alpha-tocopherol, zinc, copper, and manganese recommended by the American Medical Association appear sufficient to sustain SOD activity but inadequate to maintain alpha-tocopherol nutritional status. HPN formulations should be supplemented with selenium.     

Definition of an Efficient Transmission System Using Cooperative Games Theory

Under a context of transmission open access, a methodology to define a common transmission trunk system using economic and technical criteria is proposed. A transmission trunk system is defined as a unique and common system constituted by electrical lines and substations that are economically efficient and necessary to allow the development of an electrical market and the supply of demand in the respective electrical system at a minimum cost and in an efficient manner. The principles of cooperation and interaction between agents that are the base for the cooperative games theory are used. Simple games and the Shapley value approach are used. The proposal responds to the need to identify a common main system, common to supply and demand agents, needed in system open access schemes in electricity markets     

Approximability Properties for Second-Order Sliding Mode Control Systems

New definitions of approximability are presented for nonlinear second-order sliding mode control systems. Such robustness properties are compared with those already known for first-order methods. Sufficient conditions are obtained for second-order regularization, a sliding error estimate is derived, and some relevant examples are discussed.     

A 931 + 2T-->C transition in one COL1A2 allele causes exon 16 skipping in PRO alpha 2(I) mRNA and produces moderately severe OI

The breast clinic in the university Hospital Kuala Lumpur was started in August 1993 to cater for the increasing number of women seeking treatment for breast complaints. A four-month survey carried out from January to April 1994 found that Chinese women are more "breast conscious" than Malay and Indian women. The majority of patients were in the reproductive age group. Benign breast diseases form the majority of cases of breast diseases seen. The pick-up rate for new cases of breast cancer was 3.1%. Fine needle aspiration biopsy had a 100% sensitivity during the four-month study, and was a quick method of obtaining a diagnosis.     

Simplex sliding mode control of multi-input systems with chattering reduction and mono-directional actuators

This paper analyzes features and problems related to the application of the simplex sliding mode control to systems with mono-directional actuators and integrators in the input channel. The plain use of the method formulated in previous contributions results in unacceptable behaviors, such as control laws (the output of the mono-directional actuators), which increase without bounds. A nontrivial modification of the original algorithm is proposed; the new simplex strategy allows the fulfillment of the control objectives by means of bounded inputs from the actuators.     

Large scale hydrogen production from wind energy in the Magallanes area for consumption in the central zone of Chile

The energy proposal of this research suggests the use of places with abundant wind resources for the production of H₂ on a large scale to be transported and used in the central zone of Chile with the purpose of diversifying the country's energy matrix in order to decrease its dependence on fossil fuels, increase its autonomy, and cover the future increases in energy demand. This research showed that the load factor of the proposed wind park reaches a value of 54.5%, putting in evidence the excellent wind conditions of the zone. This implies that the cost of the electricity produced by the wind park located in the Chilean Patagonia would have a cost of 0.0213 US$ kWh^?1 in the year 2030. The low prices of the electricity obtained from the park, thanks to the economy of scale and the huge wind potential, represent a very attractive scenario for the production of H₂ in the future. The study concludes that by the year 2030 the cost of the H₂ generated in Magallanes and transported to the port of Quinteros would be 18.36 US$ MBTU^?1, while by that time the cost of oil would be about 17.241 US$ MBTU^?1, a situation that places H₂ in a very competitive position as a fuel.     

Clinical profile of arterial hypertension in patients with cerebrovascular diseases

The aim this work was to assess retrospectively the history of hypertension in patients admitted for cerebrovascular diseases. Two hundred and forty eight patients were studied (69% with ischemic strokes, 24% with hemorrhagic strokes and 7% with transient ischemic attacks. 76% of cases had a history hypertension with an evolution of ten years or more in 81% of cases. No differences in the prevalence of hypertension was observed among the different types of strokes. Of the 139 patients in whom the severity of hypertension was registered, 37% had mild, 45% moderate, 15% severe and 3% systolic hypertension. Those with severe hypertension had a higher incidence of hemorrhagic stroke. Fundoscopic examination was abnormal in 81% of the 64 patients in whom it was performed, left ventricular hypertrophy was found in 62% of the 146 patients in whom it was investigated. 51% of patients were receiving anti hypertensive treatment and it was effective in 26% of them. Thirty one percent of subjects had old lesions in the CAT scan; these subjects had a similar prevalence of hypertension and effectiveness of treatment than patients without old lesions. It is concluded that a history of more than ten years of hypertension is a risk factor for cerebrovascular disease, that severe hypertension is mostly associated to hemorrhagic strokes and that only 26% of patients with stroke had and adequate anti hypertensive treatment.     

Discontinuous feedback in nonlinear tracking problems

We consider deterministic uncertain control systems, modelled as ordinary differential inclusions. We present computable criteria for possibly discontinuous feedback control laws, guaranteeing prescribed tracking conditions, via a differential inequality approach. Moreover we show that the right concept of the corresponding (Filippov or classical) solutions is related to the choice of the (Lyapounov-like) function defining the differential inequality.     

Simplex methods for nonlinear uncertain sliding-mode control

We develop a new analysis of the behavior of simplex control methods applied to multiple-input-multiple-output nonlinear control systems under uncertainties. According to such sliding-mode control methods the control vector is constrained to belong to a finite set of (fixed or varying) vectors, with an appropriate switching logic to guarantee the specified sliding condition. Bounded uncertainties acting on the nominal system are allowed. The proposed sliding control methodology relies on the knowledge of the nominal system only. We prove rigorously the convergence of these methods to the sliding manifold in a finite time under explicit quantitative conditions on the system parameters and the available bounds of the uncertainty. Application to a robotic problem is discussed and a nonlinear example is presented.