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1.
Matrix-valued Nevanlinna-Pick interpolation with complexity constraint: an optimization approach 总被引:1,自引:0,他引:1
Blomqvist A. Lindquist A. Nagamune R. 《Automatic Control, IEEE Transactions on》2003,48(12):2172-2190
Over the last several years, a new theory of Nevanlinna-Pick interpolation with complexity constraint has been developed for scalar interpolants. In this paper we generalize this theory to the matrix-valued case, also allowing for multiple interpolation points. We parameterize a class of interpolants consisting of "most interpolants" of no higher degree than the central solution in terms of spectral zeros. This is a complete parameterization, and for each choice of interpolant we provide a convex optimization problem for determining it. This is derived in the context of duality theory of mathematical programming. To solve the convex optimization problem, we employ a homotopy continuation technique previously developed for the scalar case. These results can be applied to many classes of engineering problems, and, to illustrate this, we provide some examples. In particular, we apply our method to a benchmark problem in multivariate robust control. By constructing a controller satisfying all design specifications but having only half the McMillan degree of conventional H/sup /spl infin// controllers, we demonstrate the advantage of the proposed method. 相似文献
2.
Three test methods for measuring the rate of heat release, RHR, have been compared on the same building materials. The test methods are the OSU-box modified for O2-consumption, the STFI open arrangement and the NBS cone calorimeter. All methods are based on the oxygen-consumption technique. Radiation intensities up to 50 k Wm?2 have been applied. Thirteen different materials were tested. The results obtained using the three methods seem to be quite similar in spite of the different equipment used. The minor deviations observed in the results seem to be systematic and may be due to the different testing arrangements. There is a good correlation between results, e.g. total heat release up to 1min after ignition, obtained by the different methods. Additional information about the time to ignition is obtained simultaneously. Heat-release rates in the vertical and horizontal orientations are also compared in the NBS cone calorimeter. 相似文献
3.
A Blomqvist 《Water science and technology》2004,49(7):211-213
Urban development and industrial growth give rise to the two problems of insidious and growing pollution, and an over-exploitation of water resources. To solve these problems, various solutions have been promoted, such as multi-stakeholder dialogues, establishment of river basin committees, strong regulation, compensation for water-exporting basins and convincing politicians and the public of the need for change. 相似文献
4.
Anna A. Stec Peter FardellPer Blomqvist Lucas Bustamante-ValenciaLaurent Saragoza Eric Guillaume 《Fire Safety Journal》2011,46(5):225-233
Gaseous fire effluents contain a mixture of components, some of which are present in toxicologically significant proportions, together with water vapour and particulate matter, representing a significant challenge to the analyst. The most useful information is obtained from fire gases at about 180 °C where water and most organic species are volatile. Despite this, it is often necessary to sample and measure fire effluents for prediction of fire toxicity, estimation of the environmental impact of fires, and to understand their behaviour.Gas phase Fourier Transform Infrared (FTIR) spectroscopy has the potential to measure almost all volatiles on a continuous basis during fire. This paper considers the key parameters, which must be carefully measured and controlled in order to obtain reliable calibration data. It evaluates a number of techniques designed for calibrating an FTIR spectrometer for use in fire gas analysis with conclusions on the best system for use for each species and for specific fire tests or experimental scenarios.As few molecules in the gas phase infrared spectrum obey the Beer-Lambert law, a full set of infrared spectra at different concentrations must be obtained for each target analyte, for the actual spectrophotometer—gas cell configuration in use. In some cases, stable standard mixtures are available, and these only have to be quantitatively diluted. In other cases reactive gases such as hydrogen halides must be generated quantitatively in situ, or vapours must be generated from volatile liquids under controlled conditions, in order to obtain calibration spectra. In each case, care must be taken in the design of the sampling line and calibration system, paying particular attention to the temperature, pressure and gas flow.Gas phase FTIR is a powerful analytical tool, but requires a significant investment in time and equipment before quantitative analysis can be undertaken. Unless care is taken to ensure constant temperature and pressure in the sample lines and gas cell, significant errors will result. 相似文献
5.
Isocyanates, aminoisocyanates and amines were quantified from the combustion of 24 different materials or products typically found in buildings. Small‐scale combustion experiments were conducted in the cone calorimeter, where generally well‐ventilated combustion conditions are attained. Measurements were further made in two different full‐scale experiments. Isocyanates and amino‐compounds were sampled using an impinger‐filter sampling system with a reagent solution of di‐n‐butylamine in toluene. Filter and impinger solution were analysed separately using LC‐MS technique. Further the particulate distribution in the smoke gases was determined by impactor technique, and selected gaseous compounds quantified by FTIR. It was found in the small‐scale that isocyanates were produced from the majority of the materials tested. The highest concentration was found for glass wool insulation, and further high concentrations were found for PUR products, particleboard, nitrile rubber and melamine. Lower concentrations were found for wood and cable‐products. Amino‐isocyanates and amines were generally found from PUR products only. The distribution of isocyanates between the particulate‐ and fluid phases varied for the different materials and a tendency to enrichment of particles was seen for some of the materials. Further, when comparing the potential health hazard between isocyanates and other major fire gases (based on NIOSH IDLH‐values) it was found that isocyanates in several cases represented the greatest hazard. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
6.
DE Watenpaugh SF Vissing LD Lane JC Buckey BG Firth W Erdman AR Hargens CG Blomqvist 《Canadian Metallurgical Quarterly》1995,26(3):414-419
Atrial natriuretic peptide (ANP) is produced and secreted by atrial cells. We measured calf capillary filtration rate with prolonged venous-occlusion plethysmography of supine healthy male subjects during pharmacologic infusion of ANP (48 pmol/kg/min for 15 min; n = 6) and during placebo infusion (n = 7). Results during infusions were compared to prior control measurements. ANP infusion increased plasma [ANP] from 30 +/- 4 to 2,568 +/- 595 pmol/l. Systemic hemoconcentration occurred during ANP infusion: mean hematocrit and plasma colloid osmotic pressure increased 4.6 and 11.3%, respectively, relative to preinfusion baseline values (p < 0.05). Mean calf filtration, however, was significantly reduced from 0.15 to 0.08 ml/100 ml/min with ANP. Heart rate increased 20% with ANP infusion, whereas blood pressure was unchanged. Calf conductance (blood flow/arterial pressure) and venous compliance were unaffected by ANP infusion. Placebo infusion had no effect relative to prior baseline control measurements. Although ANP induced systemic capillary filtration, in the calf, filtration was reduced with ANP. Therefore, pharmacologic ANP infusion enhances capillary filtration from the systemic circulation, perhaps at upper body or splanchnic sites or both, while having the opposite effect in the leg. 相似文献
7.
G Armengol M Tarkkanen M Virolainen A Forus J Valle T B?hling S Asko-Seljavaara C Blomqvist I Elomaa E Karaharju AH Kivioja MA Siimes E Tukiainen MR Caballín O Myklebost S Knuutila 《Canadian Metallurgical Quarterly》1997,75(10):1403-1409
Comparative genomic hybridization (CGH) was used to detect copy number changes of DNA sequences in the Ewing family of tumours (ET). We analysed 20 samples from 17 patients. Fifteen tumours (75%) showed copy number changes. Gains of DNA sequences were much more frequent than losses, the majority of the gains affecting whole chromosomes or whole chromosome arms. Recurrent findings included copy number increases for chromosomes 8 (seven out of 20 samples; 35%), 1q (five samples; 25%) and 12 (five samples; 25%). The minimal common regions of these gains were the whole chromosomes 8 and 12, and 1q21-22. High-level amplifications affected 8q13-24, 1q and 1q21-22, each once. Southern blot analysis of the specimen with high-level amplification at 1q21-22 showed an amplification of FLG and SPRR3, both mapped to this region. All cases with a gain of chromosome 12 simultaneously showed a gain of chromosome 8. Comparison of CGH findings with cytogenetic analysis of the same tumours and previous cytogenetic reports of ET showed, in general, concordant results. In conclusion, our findings confirm that secondary changes, which may have prognostic significance in ET, are trisomy 8, trisomy 12 and a gain of DNA sequences in 1q. 相似文献
8.
9.
Early in spaceflight, an apparently paradoxical condition occurs in which, despite an externally visible headward fluid shift, measured central venous pressure is lower but stroke volume and cardiac output are higher, and heart rate is unchanged from reference measurements made before flight. This paper presents a set of studies in which a simple three-compartment, steady-state model of cardiovascular function is used, providing insight into the contributions made by the major mechanisms that could be responsible for these events. On the basis of these studies, we conclude that, during weightless spaceflight, the chest relaxes with a concomitant shape change that increases the volume of the closed chest cavity. This leads to a decrease in intrapleural pressure, ultimately causing a shift of blood into the vessels of the chest, increasing the transmural filling pressure of the heart, and decreasing the central venous pressure. The increase in the transmural filling pressure of the heart is responsible, through a Starling-type mechanism, for the observed increases in heart size, left ventricular end-diastolic volume, stroke volume, and cardiac output. 相似文献