Construction and qualification of the pre-series MQM superconducting quadrupoles for the LHC insertions

The LHC insertions will be equipped with individually powered MQM superconducting quadrupoles, produced in three versions with magnetic lengths of 2.4 m, 3.4 m, and 4.8 m. The quadrupoles feature a 56 mm aperture coil, designed on the basis of an 8.8 mm wide Rutherford-type NbTi cable for a nominal gradient of 200 T/m at 1.9 K and 5390 A. A total of 96 quadrupoles are in production in Tesla Engineering, UK. In this report we describe the construction of the pre-series MQM quadrupoles and present the results of the qualification tests.     

On the eigenvalue control of electromechanical oscillations byadaptive power system stabilizer

The eigenvalue control strategy, which utilizes an adaptive power system stabilizer, is presented for the decentralized control of damping and frequency of electromechanical oscillations in power systems. The control procedure includes the complete identification of the decoupled subsystem model in real-time from local measurements only and the assignment of its estimated electromechanical eigenvalue by the change of stabilizer parameters. The robustness and efficiency of the proposed adaptive controller to enhance overall system stability are illustrated by several examples, including the three-machine power system model     

Design and fabrication of a 1 m model of the 70 mm bore twinaperture superconducting quadrupole for the LHC insertions

For reasons of geometrical acceptance, 70 mm bore twin aperture quadrupoles are required in the LHC insertions. For an operating gradient of 160 T/m at 4.5 K, a design based on a four layer coil wound from two graded 8.2 mm NbTi conductors has been developed. Three 1 m single aperture quadrupoles of this design have been built and successfully tested. Thereafter, the magnets have been disassembled and the coils re-collared using self-supporting collars. In this paper, we describe the design features of the twin aperture quadrupole, and report on the initial collaring tests and procedures for collaring and final assembly of the 1 m magnet     

Combined low dose dipyridamole-dobutamine stress echocardiography to identify myocardial viability

OBJECTIVES: We sought to evaluate the effects of combined administration of infra-low dose dipyridamole and low dose dobutamine on assessment of myocardial viability. BACKGROUND: Low dose pharmacologic stress echocardiography with either dobutamine or dipyridamole infusion has been proposed for the recognition of myocardial viability. METHODS: Thirty-four patients with rest wall motion dyssynergy by two-dimensional echocardiography and with angiographically proved coronary artery disease underwent in combination with two-dimensional echocardiographic monitoring: 1) low dose (5 to 10 microgram/kg per min over 3 min) dobutamine infusion; 2) infra-low dose (0.28 mg/kg over 4 min) dipyridamole infusion; 3) combination of infra-low dose dipyridamole infusion immediately followed by low dose dobutamine infusion (combined dipyridamole-dobutamine). RESULTS: Follow-up rest echocardiography was available in 30 patients. After revascularization, 82 segments showed a contractile improvement of > or = 1 grade, whereas 63 segments remained unchanged. The sensitivity of dobutamine, dipyridamole and combined dipyridamole-dobutamine for predicting recovery was 72% (95% confidence interval [CI] 60.9% to 81.3%), 67% (CI 55.8% to 77%) and 94% (CI 86.3% to 97.9%), respectively. The specificity of dipyridamole, dobutamine and combined dipyridamole-dobutamine was 95% (CI 86.7% to 99%), 92% (CI 82.4% to 97.3%) and 89% (CI 78.4% to 95.4%), respectively. The accuracy of the dobutamine, dipyridamole and combined dipyridamole-dobutamine test was 80%, 79% and 92%, respectively (combined dipyridamole-dobutamine vs. dobutamine, p < 0.05; combined dipyridamole-dobutamine vs. dipyridamole, p < 0.01). CONCLUSIONS: Infra-low dose dipyridamole added to low dose dobutamine recruits an inotropic reserve in asynergic segments that were nonresponders after either dobutamine or dipyridamole alone and destined to recover after revascularization.     

Design and assembly of the pre-series quadrupoles for the LHC insertions

The LHC insertions are equipped with several different types of individually powered superconducting quadrupoles. These units comprise several quadrupole magnets and orbit correctors, and range in length from 5.3 m to 11.3 m. In spite of the variety of types and interface requirements, the design of the quadrupoles is based on the same principle where two welded half-shells provide the rigidity and alignment of the magnets and serve as a helium pressure vessel. In this paper we present the mechanical design of the LHC insertion quadrupoles, describe the initial experience in the assembly of the pre-series units, and report on the alignment measurements.     

The analysis of the renewable energy production sector in Serbia

Producing energy from renewable sources in Serbia is in its initial phase, and therefore this paper points towards the basic assumptions, potentials and institutional framework for the development of this activity in Serbia. Until recently, production and consumption of energy in Serbia was a social category, but the shift towards market economy together with the fact that Serbia has adopted Kyoto protocol, production of energy from renewable sources became a competitive and obligatory activity. Research shows that the current potentials for producing energy from renewable sources in Serbia are favorable. Besides this, the paper provides an overview of the existing institutional structure in the energy sector in Serbia, but also the short overview of the adequate legal acts. Researches that were done so far have proven that energy potentials of Serbia are insufficiently known and therefore authors will give an overview of the foreign investments in this sector and reveal the possibilities for further investing. Considering the existing know-how base and potentials for the production of equipment, geothermal energy and energy coming from biomass have been identified as priority renewable sources of energy. Producing energy from other renewable sources is also possible, but would require substantial foreign investments. As a final conclusion, the paper states that completely unused potentials for production of energy from renewable sources, together with adequately set institutional framework, would create great possibilities for foreign investments.     

A New Multilevel Conversion Structure for Grid-Connected PV Applications

A novel scheme for three-phase grid-connected photovoltaic (PV) generation systems is presented in this paper. The scheme is based on two insulated strings of PV panels, each one feeding the dc bus of a standard two-level three-phase voltage-source inverter (VSI). The inverters are connected to the grid by a three-phase transformer having open-end windings on the inverter side. The resulting conversion structure performs as a multilevel power active filter (equivalent to a three-level inverter), doubling the power capability of a single VSI with given voltage and current ratings. The multilevel voltage waveforms are generated by an improved space-vector-modulation algorithm, suitable for the implementation in industrial digital signal processors. An original control method has been introduced to regulate the dc-link voltages of each VSI, according to the voltage reference given by a single maximum power point tracking controller. The proposed regulation system has been verified by numerical simulations and experimental tests with reference to different operating conditions.     

Sublingual nucleotides and immune response to exercise

ABSTRACT: Evidence exists regarding the potential role of exogenous nucleotides as regulators of the immune function in physically active humans, yet the potential use of nucleotides has been hindered by their low bioavailability after oral administration. We conducted a double-blind, placebo-controlled, randomized trial to assess the effect of sublingual nucleotides (50?mg/day) on salivary and serum immunity indicators as compared to placebo, both administered to healthy males aged 20 to 25?years for 14?days. Sublingual administration of nucleotides for 14?days increased serum immunoglobulin A, natural killer cells count and cytotoxic activity, and offset the post-exercise drop of salivary immunoglobulins and lactoferrin (P??0.05). It seems that sublingual administration of nucleotides for two weeks considerably affected immune function in healthy males.