Pressure-coefficient trends for mixed propellants

Spline fitting has been used in processing measurements on the pressure dependence of the burning rate to obtain additional information on the variation in the pressure coefficient v as affected by grain size and composition, as well as by the nature of the components. Conclusions are drawn on the burning mechanism. The peak on v(p) is due to serial-parallel conversion of APC in the condensed and gas phases and to changes in the relative significance of the chemical stages. There is a minimum at elevated pressures for many propellants, which in some cases is transformed into a plateau or inflection on account of interaction between the fuel and the oxidizing agent in the diffusion-kinetic hydrocarbon flame.Chernogolovka. Translated from Fizika Goreniya i Vzryva, Vol. 29, No. 2, pp. 68–72, March–April, 1993     

Improving the testability of switched-capacitor filters

A design-for-test methodology for SC filters is presented, based on an architecture using some additional circuitry and providing extra capabilities for both off- and on-line tests. The approach uses a comparison (voting) mechanism to indicate whether or not two copies of a filter element (a biquad, for instance) have a similar response during their actual operation. The design and implementation of a few filter examples are included to assess the potential usefulness of this new approach.     

Maternal serum screening for trisomy 18 in the first trimester of pregnancy

It is widely accepted that thrombocytopenia associated with liver cirrhosis is caused by increased platelet destruction in the enlarged spleen, but this issue has not yet been analysed sufficiently in terms of platelet production. Thrombopoietin is produced mainly in the liver and strongly promotes platelet production. We studied serum thrombopoietin and the levels of its mRNA in liver tissue of cirrhotic patients and also in a rat model of liver cirrhosis. Furthermore, to clarify the influence of the spleen, we investigated thrombopoietin mRNA in splenectomized rats. The serum thrombopoietin level in humans with liver cirrhosis was not significantly reduced instead of thrombocytopenia. The expression of thrombopoietin mRNA in liver tissue decreased with the progression of liver cirrhosis in both patients and the rat model and no compensatory expression was observed in other organs or non-parenchymal cells. The level of thrombopoietin mRNA did not differ significantly in splenectomized cirrhotic rats before or after administration of dimethylnitrosamine, but was lower than that in splenectomized rats without cirrhosis. We conclude that thrombocytopenia in liver cirrhosis is caused not only by platelet destruction but also by decreased platelet production, perhaps due to reduction of thrombopoietin mRNA in the liver.     

Putting reader roles to the test: an ethnomethodological approach

That readers read within roles has long been argued by literary theorists and more recently by technical communication theorists. Yet few scholars have attempted to put their theories to a test. The study reported in this paper attempts to do by using a conversation analysis tool called ethnomethodology. In an experimental setting, subjects were videotaped reading and responding to a set of instructions. Their responses indicate that: readers will often choose to play a role different from the one embedded in a text, especially if the text role offends them in some way; readers with similar education and interest may display different reader roles, making these roles difficult to predict; and within a single reading, a reader may change roles frequently. The paper concludes by discussing the implications of the findings and the appropriateness of ethnomethodology for reader-role research     

Factors affecting the quality of low- and medium-level solidified wastes

Main Science Center of the Russian Federation, A. A. Bochvara All-Russia Scientific-Research Institute of Standardization in Machine Engineering. Atomnaya énergiya, Vol. 79, No. 3, pp. 197–200, September, 1995.     

Ohmic contact and transport properties of II–VI Green/Blue laser diodes

The employment of the Zn(Se,Te) pseudo-graded contacting scheme to p-type ZnSe-based alloys contributes directly to the recent demonstration of room temperature continuous-wave operation of II– VI green-blue laser diodes. Contact ohmicity is maintained down to cryogenic temperatures which enabled the investigation of electrical transport properties associated with the p-type nitrogen-doped ZnSe, Zn(S,Se), and (Zn,Mg)(S,Se). The observation of both persistent photoconductivity and a metastable population of holes which are in thermodynamic equilibrium with hydrogenic acceptors having reduced activation energy suggests the presence of a DX-like behavior for holes in p-type (Zn,Mg)(S,Se).     

Effect of neutron radiation on the structure and properties of uranium monosilicide

A. A. Bochvar All-Union Scientific-Research Institute of Standardization in Machine Engineering. Moscow Engineering Physics Institute. Translated from Atomnaya énergiya, Vol. 77, No. 2, pp. 123–129, August, 1994.     

Dynamic analysis of the NPP pressure sensor system

The aim of the work was to develop on-line methods of control and diagnostics of pressure sensors at a NPP. The analysis was carried out along two lines:

1. i) The detection system including the sensor itself was modeled theoretically to obtain and study its transfer function, and to establish correspondence between the spectral characteristics of the pressure signal.

2. ii) The numerical processing of the signal using the AR technique to reconstruct the transfer function and evaluate the system's response, to a step impulse, as well as the spectral analysis. The hydraulic model presented indicate that the spectral lines observed at 10 Hz are due to longitu-dinal oscillations of water in the system branches, while the response time of the detection system is effectively the time of signal retardation in the porous ceramic diaphragms of the δ-cell of the sensor itself.