Non-linearity in pulmonary arterial circulation process

This paper describes the procedure for determination of the non-linearity present in the pulmonary arterial circulation process. A method of investigation of the non-linearity by applying control theory is first described. The basic linear model of the circulation process is then discussed and the parameters of the linear model are estimated. The basic model is non-linearized by considering the presence of an additional actuating signal to the model to account for the effective non-linearity of the circulation process. The characteristic of the non-linearizing signal is then determined by examining the resemblance between the model response and the actually observed pressure contour characteristics. The system non-linearity with respect to the determined characteristic of the non-linearizing signal is discussed.     

Structural characterization of electrodeposited boron

Structural characterization of electrodeposited boron was carried out by using transmission electron microscopy and Raman spectroscopy. Electron diffraction and phase contrast imaging were carried out by using transmission electron microscopy. Phase identification was done based on the analysis of electron diffraction patterns and the power spectrum calculated from the lattice images from thin regions of the sample. Raman spectroscopic examination was carried out to study the nature of bonding and the allotropic form of boron obtained after electrodeposition. The results obtained from transmission electron microscopy showed the presence of nanocrystallites embedded in an amorphous mass of boron. Raman microscopic studies showed that amorphous boron could be converted to its crystalline form at high temperatures.     

A note on the correct evaluation of junction capacitance of a solar cell

In the fabrication of low-cost solar cells one has often to contend with finite series and shunt resistances. These tend to give misleading values of the junction capacitance as measured with an ordinary bridge. The problem is discussed analytically and graphical plots are given for determination of the true values from the measured ones. Practical use of these plots is discussed and illustrated with the help of experiments on thin-film Cu₂S-CdS solar cells.     

ADI Method for Heat Conduction Problems in an Orthogonal Coordinate System

A mathematical model has been developed for the time-dependent heat conduction process in a region of arbitrary geometry. An alternating direction implicit (ADI) scheme has been worked out for the computer solution of the problem in three space dimensions. The time and nodal propagation of the errors are depicted graphically. Also included in the computer software is a subroutine for plotting the isotherms in various geometries.     

Identification and Expression of the Saccharomyces cerevisiae Cytoplasmic Tryptophanyl-tRNA Synthetase Gene

The enzymes that aminoacylate tRNAs have been studied extensively and can be organized into two distinct classes based on signature sequences and the position of aminoacylation. The class I enzymes have canonical HIGH and KMSKS sequences as part of a Rossman fold nucleotide-binding site. The tryptophan-specific enzymes have been placed in class I based on analysis of the cognate genes from Escherichia coli, B. stearothermophilus, B. taurus, and Homo sapiens. An unidentified open reading frame (ORF) on Saccharomyces cerevisiae chromosome XV, HRE342, has 46% identity with the bovine tryptophanyl-tRNA synthetase and possesses the appropriate signature sequences. The predicted molecular weight of the putative HRE342 protein also closely matched the expected monomer size of the S. cerevisiae enzyme. The HRE342 ORF plus about 250 bp of 5′ and 3′ flanking sequence was amplified by polymerase chain reaction, cloned into a 2 μ based vector, and transformed into a host strain, S. cerevisiae JG369.3B. Nucleotide sequence analysis of the clone confirmed the presence of HRE342. Extracts from transformed yeast have a 30- to 100-fold increase in specific activity of the tryptophanyl-tRNA synthetase. An HRE342 locus in a diploid strain, PTY33XPTY44, was disrupted with a LEU2 insert. Sporulation and tetrad analysis of the HRE342::LEU2 strain demonstrated that HRE342 is an essential gene. We conclude that HRE342 is the S. cerevisiae gene encoding the cytoplasmic tryptophanyl-tRNA synthetase, WRS1. A search of the Saccharomyces Genome Database using amino acid sequences from other eukaryotic aminoacyl-tRNA synthetases suggests there is sufficient similarity to identify both class I and class II genes. © 1997 by John Wiley & Sons, Ltd.     

Modeling and analysis of singular systems via orthogonal triangular functions

This paper presents a new approach to singular system analysis by modeling the system in terms of orthogonal triangular functions (TFs). The proposed method is more accurate compared to block pulse function-based analysis with respect to mean integral square error (MISE). A numerical example involving four states of a singular system is treated and solutions obtained thereof. Four tables and relevant curves are presented to compare the respective coefficients in block pulse function (BPF) domain as well as in TF domain. The percentage error of the samples determined via TF domain are compared with the exact samples of the states. Furthermore, MISE for both BPF and TF analysis are computed and compared to reveal the efficiency of TF-based analysis.     

A new recurslve method for the analysis of linear time invariant dynamic systems via double-term triangular functions （DTTF） in state space environment

This paper presents a new recursive method for system analysis via double-term triangular functions (DTTF) in state space environment. The proposed method uses orthogonal triangular function sets and proves to be more accurate as compared to single term Walsh series (STWS) method with respect to mean integral square error (MISE). This has been established theoretically and comparison of error with respect to MISE is presented for clarity. A numerical example is treated to establish the proposed method. Relevant curves for the solutions of states of the dynamic system are also presented with plots of percentage error for DTTF-based analysis.     

Reexamination of the Kaolinite-to-Mullite Reaction Series

The kaolinite-to-mullite reaction series was reexamined with special attention to the nature of the metaphase, the eontroversial spinel phase, and the cause of the exothermic peak at 980°C. Amorphous SiO₂ forms during the exothermic reaction; it can be leached by alkali extraction. When the residual cubic phase is heated further, it forms mullite only. This result indicates that the cubic phase is an Al-Si spinel and that metakaolinite is an AI₂O₃-SiO₂ compound. It was established that the exotherm exhibited by kaolinite at 980°C represents the sudden transformation of metakaolinite to Al-Si spinel, the crystallization of mullite, and the liberation of amorphous SiO₂. The AI-Si spinel has the same composition as mullite, containing both AI(IV) and AI(VI). This spinel transforms into mullite at the second exothermic peak; no amorphous SiO₂ is liberated.