Feedback factorizing control of 3-D transfer functions via a canonical state-space model

The problem factorizing (separating) the transfer function of a given SISO 3-D discrete system, ie of a system depending on three independent variables, is considered. The 3-D system is assumed to be available in its transfer function representation, which is converted to a canonical state-space model by a simple inspection procedure. Then applying state-feedback to this canonical model we choose the feedback matrix gain (under certain conditions) such that the transfer function of the closed-loop system has the desireed factorized form, ie a product of three 1-D transfer functions each one being dependent on a single variable. The method is illustrated by a nontrivial numerical example.     

Seawater desalination by reverse osmosis

Until comparatively recently the purification of sea or brackish water depended largely on some form of distillation. In recent years, however, a number of industrial concerns have directed increasing attention to processes depending on reverse osmosis. A number of large plants have been installed and this article reviews the present state of reverse osmosis technology and the factors determining its efficiency. Its advantages include its relatively low fuel consumption, and in this respect further substantial savings are in prospect.     

Effect of labour and surgical stress on serum free fatty acids

Serum free fatty acids (FFA) in 100 parturient (50 primiparous and 50 multiparous volunteers) and 50 female patient (30 patients 20–30 years age group and 20 patients 31–50 yrs age group) volunteers undergoing elective major abdominal surgery were monitored during different stages of delivery and surgery respectively. FFA increased in both primiparous and multiparous from full term (46 mg%) to second stage of labour (60 mg%) and gradually decreased to 38 mg% on the third day postpartum. The intergroup comparison between primiparous and multiparous was significant. Surgical stress also increased FFA from the day of admission (21 mg%) to the preoperative stage (35 mg%). The intergroup comparison between 20–30 yrs age group and 31–50 yrs age group did not show any significant change.     

Standardization of a dilution method for cyclosporin (C2) estimation in renal transplant patients

Accurate monitoring of blood cyclosporin C2 levels is vital to prevent over immunosuppression and acute renal toxicity in patients who receive organ transplant. The matrix used to dilute patients’ C2 samples prior to the assay affected the final measured values. Hence there was a need to develop a method of dilution that would accurately estimate C2 levels when cyclosporin levels were beyond the calibration range of the method employed. Whole blood, cyclosporin free hemolysate and cell and protein free supernatant obtained after pretreatment of normal blood were used to dilute patients’ C2 samples. C2 was measured in 188 patients using the supernatant method of dilution. C2 was correlated with Co and dose of cyclosporin received by the patient. The use of cell and protein free supernatant obtained after pretreatment of normal blood as a C2 diluent detected higher levels of C2 in the sample. Measured C2 correlated significantly with Co and the cyclosporin dose received by the patient. The uniformly aqueous cell and protein free supernatant ensures uniform dilution of the patients’ C2 sample and measures higher cyclosporin levels.     

Pre and post analytical errors in lipid determination

A number of pre analytical variables affect lipid determinations. These include posture during blood sampling, the duration of tourniquet application and fasting, the time of day when blood is collected, the concentration and type of anticoagulant used for blood collection to name just a few. Effect of life style such as diet, alcohol and caffeine consumption, smoking, and exercise influence lipid determinations. Disease states such as infection, diabetes, nephrotic syndrome and heart disease culminating in myocardial infarction and conditions such as obesity and pregnancy influence lipid profiles. A variety of drugs ranging from diuretics to oral contraceptives to immunosuppressive drugs induce alterations in the patient's lipid profile. Post analytical variables impacting on the interpretation of laboratory data such as in the determination of the true mean of a lipid constituent would depend on the number of specimens analyzed, the analytical variability of the method and approaches to handling data such as the use of relative range to estimate the effect of biological variability on the computed mean value.     

Study of adenosine deaminase activity in various arthritic conditions

Aim of present study was to compare the adenosine deaminase (ADA) activity in various types of arthritis conditions with synovial effusion. No. significant difference was observed in ADA activity in serum of control and study groups but results have shown a definite pattern of ADA activity in synovial fluid in various arthritic conditions. The highest value of ADA activity was observed in synovial fluid of patients with tubercular arthritis followed by rheumatoid, septic, osteo and post traumatic arthritis. Thus measurement of ADA activity in synovial fluid can be used as a parameter of differential diagnosis of arthritis specially tubercular in initial stages.     

Query processing in a retrospective document retrieval system that uses word fragments as language elements

The structure of a retrospective information retrieval system that uses equifrequent word or text fragments is described, and its advantages over word oriented systems are mentioned briefly. Word fragments are proposed as retrieval elements, and a discussion is given of the changes required in order to process a query. Some necessary modifications in the treatment of logical operators are described, and two conditions are postulated as necessary for the successful operation of the system. Aspects of query processing are illustrated by experimental results obtained from single and two-term queries applied to a portion of the MARC tapes.     

Selectivity nomographs for classical filters

Nomographs for determining the filter order of classical filters based on selectivity requirements are presented. The selectivities for a variety of standard classical filters are summarized in equation form and the general selectivity nomograph is constructed. The selectivity equations are then converted into nomograph form by applying the relationship between the transfer function and the response slope. Design examples are presented to demonstrate the usefulness of the selectivity nomographs. These nomographs can be used to gauge filter performance and combined with optimization techniques can yield superior classical filter designs.     

On orthogonal polynomials

A study is made of the orthogonal polynomials on certain curves in the complex plane. Necessary and sufficient conditions for a set of polynomials to be orthogonal on the curves are obtained in terms of symmetric matrices. The relations of the symmetric matrices to Toeplitz matrices and innerwise matrices are shown.     

Contributions of Emergent Literacy Skills to Name Writing, Letter Writing, and Spelling in Preschool Children

The purpose of this study was to examine which emergent literacy skills contribute to preschool children's emergent writing (name-writing, letter-writing, and spelling) skills. Emergent reading and writing tasks were administered to 296 preschool children aged 4-5 years. Print knowledge and letter-writing skills made positive contributions to name writing; whereas alphabet knowledge, print knowledge, and name writing made positive contributions to letter writing. Both name-writing and letter-writing skills made significant contributions to the prediction of spelling after controlling for age, parental education, print knowledge, phonological awareness, and letter-name and letter-sound knowledge; however, only letter-writing abilities made a significant unique contribution to the prediction of spelling when both letter-writing and name-writing skills were considered together. Name writing reflects knowledge of some letters rather than a broader knowledge of letters that may be needed to support early spelling. Children's letter-writing skills may be a better indicator of children's emergent literacy and developing spelling skills than are their name-writing skills at the end of the preschool year. Spelling is a developmentally complex skill beginning in preschool and includes letter writing and blending skills, print knowledge, and letter-name and letter-sound knowledge.