Optimal linear regulators: The discrete-time case

In this paper the optimal discrete-time linear-quadratic regulator problem is carefully presented and the basic results are reviewed. Dynamic programming is used to determine the optimization equations. Special attention is given to problems unique to the discrete-time case; this includes, for example, the possibility of a singular system matrix and a singular control-effort weighting matrix. Some problems associated with sampled-data systems are also summarized, e.g., sensitivity to sampling time, and loss of controllability due to sampling. Computational methods for the solution of the optimization equations are outlined and a simple example is included to illustrate the various computational approaches.     

Full process for integrating silicon nanowire arrays into solar cells

A novel process was developed for integrating silicon nanowire arrays into solar cells. n-Type silicon nanowires were grown by chemical-vapour deposition via the gold-catalysed vapour-liquid-solid method, on a p-type silicon substrate. After the growth, the nanowire array was planarized, by embedding the nanowires in a spin-on glass matrix and subsequent chemical-mechanical polishing of the front surface. This planarization step allows to deposit a continuous and uniform conductive film on top of the nanowire array, and thus to form a high-quality front electrical contact. For an illumination intensity of 100 mW/cm², our devices exhibit an energy conversion efficiency of 1.9%. The main performance limiting factor is a high pn junction reverse current, due to contamination by the growth catalyst or to a lack of passivation of surface electronic defects.     

Sulla risoluzione (Nel caso lineare) di un particolare problema di speculazione

This Note takes again a late work byM. Volpato, which indicates the resolution. with method of dynamics programming, of a non-linear problem in Econometrics, for decide theoptimum in a buying and selling business. When involved functions are linear, the question becomes aLP problem whose solutions is given from known methods. Here, subject shows, by method of Volpato, a very easy proceeding involving only comparisons among the dates of question. Moreover, the result confirms an intuitive rule of Economical Policy which, perhaps for the first time, is strictly justified.

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Lavoro eseguito nell'ambito dell'attività del Gruppo di Ricerca n⁰ 38 (Univ. ca' Foscari-Venezia) del Comitato per la matematica del C.N.R. per l'A.A. 1963–64.     

IN PRACTICE: A CONSULTANT' S VIEWPOINT DISTRIBUTED COMPUTING ENVIRONMENTS Process and Organization Issues

When the disjointed networks and technology platforms of an organization are connected through a distributed computing environment, companies quickly discover there' s more to manage than the technical architecture. Chief among concerns are how to structure the computing environment, deliver the distributed applications, and organize the IS department to support and maintain them     

Glycosphingolipids of white cells lymphoid tissue and bone marrow

Glycosphingolipids of lymphoid tissues, bone marrow cells, mixed blood leucocytes, separated lymphocytes, and granulocytes from large white pigs were analyzed by thin layer and gas liquid chromatographies. The composition of the glycosphingolipids of thymus and blood leucocytes (mixed population) was similar, and trihexosyl ceramide (galactosyl-[1–4]-galactosyl-[1–4]-glucosyl-[1–1]-ceramide) was the major glycosphingolipid component of both tissues. The fatty acid fractions of all glycolipids from the two tissues were analyzed, and gross differences are discussed. Blood lymphocytes had a higher content of glycosphingolipids/mole phospholipid or mg protein than thymus lymphocytes obtained by a gentle washing of sliced tissue. Similar and more pronounced differences were obtained when the glycosphingolipid content of bone marrow cells (>50% polymorphonuclear neutrophils) was compared with that of blood polymorphonuclear neutrophils. In general, most of the blood leucocytes were richer in glycosphingolipids than most of the cells of the lymphoid tissues and bone marrow. These results indicate a marked difference in lipid composition between blood polymorphonuclear neutrophils and bone marrow cells. It is possible that certain of the biophysical properties which characterize blood polymorphonuclear neutrophils and which derive from changes in the cell periphery of immature granulocytes are connected with these differences in membrane lipid composition.     

Autonomic reactivity of high and low ego-strength subjects to repeated anxiety eliciting scenes.

Conducted an experiment to answer the question of whether patients labeled high or low in ego-strength differentially responded to scenes designed either to elicit anxiety or produce little (neutral) affect. Ss were 48 18-62 yr old male psychiatric inpatients. High ego-strength Ss initially responded to anxiety scenes with reliably more affect than to neutral scenes as indexed by their skin conductance level, heart rate measures, and by responses to the Fear Thermometer test and Affect Adjective Check List. Repeated presentations of anxiety scenes across 4 sessions led to a rapid extinction effect for the autonomic measures recorded. The same comparisons over these indices for low ego-strength Ss failed to produce any reliable differences. This latter result occurred despite the finding that low ego-strength Ss reported reliably more psychopathology on the pretest MMPI and Fear Survey Schedule when compared with high ego-strength Ss. Differences in baseline autonomic reactivity and responding to a standard stressor test were not obtained between ego-strength conditions. Data from nontreated Ss suggest that the presentation of anxiety scenes produced no ill effects for either ego-strength population. A tentative learning theory interpretation of the data is advanced. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Glycosphingolipids of human thyroid

Glycosphingolipids were isolated from total lipids of female and male human thyroids by alkaline hydrolysis, silicic acid, diethylaminoethyl-celluose and thin layer chromatography and analyzed by gas liquid chromatography. On the basis of their mobility in two dimensions on thin layer chromatography, IR analysis, and of sugar molar ratio, four neutral glycolipids, a sulfatide, and a hematoside fraction were identified. Glucosyl, plus galactosyl ceramide, and trihexosyl ceramide were the major fractions and accounted for 33% and 28% of total neutral glycolipids, respectively. Dihexosyl ceramide was a mixture of lactosyl and digalactosyl ceramide. The acidic lower phase glycolipids comprised ceramide galactosyl sulfate as the major component of male thyroids. Hematoside was identified tentatively as a minor component of the thyroids of both sexes. Major fatty acids of all neutral glycolipid fractions were 20∶0, 22∶0, 24∶0, and 24∶1; 24∶0 and 24∶1 for sulfatides. Low proportions of α-hydroxy fatty acids were identified. Total neutral glycosphingolipids of male thyroids were comparable in quantities with human liver but lower than kidneys, leucocytes, and platelets. Male thyroids comprised higher quantities of neutral glycosphingolipids (4.04±0.32 μmoles/g total lipid) as compared to females (2.34±0.21 μmoles/g total lipid), and much higher sulfatide than the females. These marked differences may suggest that the biosynthesis of the glycosphingolipids in the thyroid gland is under hormonal control. Similarities in glycosphingolipid composition of human thyroid and kidney are discussed in relation to a possible role played by glycolipids in ion transport, which is a common feature of the two organs.     

Some computational aspects of the matrix exponential

Matrix norms that satisfy the Schwarz inequality are used to determine upper bounds for the error in some common computations involving the matrix exponential function.     

Effects of ten hours of implosive therapy in the treatment of outpatients: A preliminary report.

The present report, investigating the effectiveness of implosive therapy (IT) with outpatients, mainly was designed as an exploratory study to determine the feasibility and value of more effective evaluations of this new behavioral therapy. 40 patients were divided into 1 experimental and 3 control groups. Only the IT group showed a consistent trend to shift away from psychopathology as measured by the MMPI. Some evidence is presented that the changes in this group are not due to the number of therapy sessions, to the skills and personal qualities of the therapists independent of the treatment technique, to the termination of treatment, or to effects resulting from the commitment to and expectation of professional treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)