scispace - formally typeset
Search or ask a question

Showing papers on "TEC published in 1989"


Journal ArticleDOI
Shunichi Numata1, Takao Miwa1
01 Jun 1989-Polymer
TL;DR: In this paper, the effects of linearity and rigidity of molecular chains and their cohesive energy density on the thermal expansion coefficient (TEC) and modulus of polyimide films were investigated, using various uniaxially stretched films.

47 citations


Journal Article
01 Jan 1989-Thymus
TL;DR: The concept of T EC heterogeneity is extended and might also be useful to further understanding of TEC origin, development and functions.
Abstract: Rat thymic epithelial cells (TEC) have been studied by a panel of monoclonal antibodies specific for single cytokeratin polypeptides or cytokeratin pairs. Using various combinations of single and double immunostainings 6 TEC subsets (CK types) were identified, each characterized by different cytokeratin expression. Subcapsular/perivascular TEC (TEC-CK type 1) share cytokeratins 7, 8, 19 with a subset of medullary TEC, while cortical TEC were reactive with anti-CK 8 and anti-CK 18 mAbs only (TEC-CK type 2). Additional 4 subsets were identified in the medulla; TEC-CK type 3 (CK 8 + 18 + 19 +), TEC-CK type 4 (CK 8 + 10 + 18 + 19 +), TEC-CK Type 5 (CK 8 + 10 + 10 +) and TEC-CK type 6 positive only with CK 8 of all above cytokeratins. This study extends the concept of TEC heterogeneity and might also be useful to further understanding of TEC origin, development and functions.

32 citations


Journal ArticleDOI
TL;DR: Evidence for the first time is presented that human recombinant interleukin 1 (IL1) and IL1-containing mixed cytokine preparations induced DNA synthesis of TEC as measured in a 48-hr stimulation assay and that IL1 induced a profound change in the morphology of T EC.

29 citations


Journal ArticleDOI
TL;DR: On two separate evenings in September 1982, rockets were launched into the bottomside equatorial F{sub 2} region off the coast of Natal, Brazil, to create a hole in ionization as mentioned in this paper, and the hole-induced depletions in total electron content (TEC) of more than 10{sup 16} el/m{sup 2} were observed over horizontal distances of at least 60 km from the chemical injection point.
Abstract: On two separate evenings in September 1982, rockets were launched into the bottomside equatorial F{sub 2} region off the coast of Natal, Brazil, to inject chemicals, consisting of mainly H{sub 2}O and CO{sub 2}, to create a hole in ionization. The chemicals were injected near the height where the density gradient was steepest, and at a time when the F{sub 2} region was rising rapidly to see whether plasma bubble irregularities could be generated from instabilities triggered by the ionization hole. On both occasions, hole-induced depletions in total electron content (TEC) of more than 10{sup 16} el/m{sup 2} were observed over horizontal distances of at least 60 km from the chemical injection point. The eastward drifts of these artificial depletions were observed by the time difference in the TEC features observed at various TEC monitoring stations, and from the changing range of oblique ionosonde echoes observed by an ionosonde located 300 km magnetically east of the chemical release point. Their subsequent evolution into plasma bubble irregularities was demonstrated from the observations of spread F echoes, strong amplitude scintillation, and TEC depletion at distances of from 300 to 500 km eastward of the release points. The fact that similar behavior ofmore » the ionosphere was observed during the evenings of both rocket chemical releases, and on no other nights of the campaign, is strong evidence of successful artificial generation of bubble irregularities by chemical injection into the bottomside F{sub 2} region.« less

18 citations


Journal ArticleDOI
TL;DR: In this article, single crystals of CuInSe2 have been fabricated by the vertical Bridgman method using a conventional Czochralski crystal-pulling system adapted for this purpose.
Abstract: Single crystals of CuInSe2 have been fabricated by the vertical Bridgman method. A conventional Czochralski crystal-pulling system was adapted for this purpose. An accelerated crucible-rotation tec...

15 citations


01 Jan 1989
TL;DR: The NASA/JPL Rogue Receiver as mentioned in this paper is an 8-satellite, non-multiplexed, highly digital global positioning system (GPS) receiver that can obtain dual frequency data either with or without knowledge of the P-code.
Abstract: The NASA/JPL Rogue Receiver is an 8-satellite, non-multiplexed, highly digital global positioning system (GPS) receiver that can obtain dual frequency data either with or without knowledge of the P-code. In addition to its applications for high accuracy geodesy and orbit determination, the Rogue uses GPS satellite signals to measure the total electron content (TEC) of the ionosphere along the lines of sight from the receiver to the satellites. These measurements are used by JPL's Deep Space Network (DSN) for calibrating radiometric data. This paper will discuss Rogue TEC measurements, emphasizing the advantages of a receiver that can use the P-code, when available, but can also obtain reliable dual frequency data when the code is encrypted.

12 citations


01 Jan 1989
TL;DR: A detailed sensitivity study on the recently developed Translational Energy Criteria (TEC) confirmed that the TEC is consistent with the well accepted conclusion implying that a harder head impact causes a more severe head injury.
Abstract: In this paper, a detailed sensitivity study on the recently developed Translational Energy Criteria (TEC) was accomplished. The results of the study confirmed that the TEC is consistent with the well accepted conclusion implying that a harder head impact causes a more severe head injury. In the TEC analysis, the energy function increases as the impact momentum increases. Thus, a harder hit (higher momentum) causes a more serious head injury and has a higher EC2 value. The results of the TEC analysis also showed that the power function, the impact onset rate and skull fracture correlate well. As a result, the TEC may also be used to predict the occurrence of skull fracture in impact situations.

10 citations



01 Jan 1989
TL;DR: In this paper, a detailed sensitivity study on the recently developed Translational Energy Criteria (TEC) was accomplished and the results of the study confirmed that the TEC is consistent with the well accepted conclusion implying that a harder head impact causes a more severe head injury.
Abstract: In this paper, a detailed sensitivity study on the recently developed Translational Energy Criteria (TEC) was accomplished. The results of the study confirmed that the TEC is consistent with the well accepted conclusion implying that a harder head impact causes a more severe head injury. In the TEC analysis, the energy function increases as the impact momentum increases. Thus, a harder hit (higher momentum) causes a more serious head injury and has a higher EC2 value. The results of the TEC analysis also showed that the power function, the impact onset rate and skull fracture correlate well. As a result, the TEC may also be used to predict the occurrence of skull fracture in impact situations.(A) For the covering abstracts of the conference see IRRD 826430.

5 citations


Proceedings ArticleDOI
06 Aug 1989
TL;DR: In this article, a high permeability to cesium has been revealed in tungsten layers transferred from the thermionic energy converter (TEC) emitter to collector.
Abstract: A high permeability to cesium has been revealed in tungsten layers transferred from the thermionic energy converter (TEC) emitter to collector. Absorbed cesium reduces the energy of cesium desorption from the collector surface. Collector specimens with tungsten films deposited by the emitter-to-collector mass transfer proceeding in the TEC interelectrode space have been studied, and thermoemission microscopy investigations of the process have been carried out. A relationship has been established between the position of the work function minima in curves e psi =f(T/T/sub CS/) and cesium vapor pressure. >

3 citations


Proceedings ArticleDOI
02 Jun 1989
TL;DR: In this article, the variations of thermal expansion coefficient (TEC) and viscosity with refractive index modifier dopants have been measured and the expression αTg2 = constant holds well for glasses not containing Li and allows the magnitude and direction of changes in TEC to be predicted from changes in tg.
Abstract: The variations of thermal expansion coefficient (TEC) and viscosity with refractive index modifier dopants have been measured. When PbF2 replaces BaF2 there is an increase in TEC accompanied by a decrease in both T5 and viscosity at fibre pulling temperature whereas when PbF2 replaces NaF there is a drop in TEC with a complementary increase in Tg and viscosity at fibre pulling temperature. Similarly when HfF4 replaces ZrF4 the TEC decreases while Tg and viscosity at fibre pulling temperature increase. The expression αTg2 = constant holds well for glasses not containing Li and allows the magnitude and direction of changes in TEC to be predicted from changes in Tg. The activation energy for viscous flow at small dopant levels varied little indicating that the magnitude and direction of viscosity changes can be predicted from Arrhenius behaviour and Tg differences. The stresses in a fibre resulting from expansion mismatch and those mechanically induced during drawing as a result of viscosity mismatch are small for common core clad structures. The thermal and mechanical stresses are generally of the same magnitude and opposing sign; they therefore do not enhance or degrade fibre strength.

Proceedings ArticleDOI
06 Aug 1989
TL;DR: In this paper, a flame-heated, air-cooled thermionic conversion (TEC) at the Eindhoven University of Technology is described, and the characterization of the materials used in the convertor, some design considerations for the aircooled test TEC constructed recently, and test results for a sodium heat pipe collector are discussed.
Abstract: Research on thermionic conversion (TEC) at the Eindhoven University of Technology is described. The initial fundamental research on emitter materials has been followed by the design, construction and testing of a flame-heated, air-cooled TEC. Air cooling of the collector with a sodium heat pipe has been preferred as it improves the thermodynamical behavior of the TEC in its prime application area, the electrical generator of a total energy module (TOTEM). Some results of the characterization of the materials used in the convertor, some design considerations for the air-cooled test TEC constructed recently, and test results for a sodium heat pipe collector are discussed. >

Proceedings ArticleDOI
06 Aug 1989
TL;DR: In this paper, a theoretical model of the pulse mode of the TEC with Cs+N/sub 2/ filling is developed, and the converter characteristics are calculated and the optimum conditions for energy conversion are found.
Abstract: On the basis of an analysis of the processes observed in the cesium-nitrogen plasma a theoretical model of the pulse mode of the thermionic converter (TEC) with Cs+N/sub 2/ filling is developed. The converter characteristics are calculated, and the optimum conditions for energy conversion are found. The effects of ion production nonequilibrium are investigated. The decay stage of the thermionic diode simulating a thermionic converter with the Cs+N/sub 2/ plasma is studied experimentally. The period of plasma decay is shown to increase sharply with an increase in the nitrogen pressure as soon as it exceeds a certain value. This evidence supports the idea of cesium ionization being effected by nitrogen. The reasons for such a strong dependence of the ionization rate on nitrogen pressure are discussed. >

01 Nov 1989
TL;DR: In this paper, a dual frequency CPS receiver measuring ionospheric delay or TEC (Total Electron Content) named GTR-2 was constructed in BIPM (Bureau International des Poids et Mesures) and operates in regular base since October 1988.
Abstract: : A dual frequency CPS receiver measuring ionospheric delay or TEC (Total Electron Content) named GTR-2 was constructed in BIPM (Bureau International des Poids et Mesures) [1], and operates in regular base since October 1988. CRL (Communications Research Laboratory) also has completed a development of the same equipment this year. It has almost same performances as GTR-2 in BIPM. By using the two receivers, we have begun to compensate the time transfer results obtained from the conventional GPS time transfer receivers between Japan and Europe under the cooperation of CRL and BIPM for a construction of a tight time-transfer link by using GPS satellite. This paper shows the improvement of GPS time transfer results by using the ionospheric delays measured by GTR-2. For a highly transportable geodetic purpose VLBI (Very Long Baseline Interferometer) station, CRL has another application program of CTR-2. For this compact VLBI station, we are making a study of ionospheric compensation of the signal from radio stars by using the TEC data obtained from GTR-2.

Journal ArticleDOI
T.J. Taylor1, Y.P. Khanna1
TL;DR: In this article, a study has been carried out to evaluate the accuracy of thermal expansion coefficients (TEC) data obtained from two commercial thermomechanical analyzers, and the accuracy has been improved to about ± 2% on a borosilicate sample of TEC = 4.7×10−6C−1.

30 Jun 1989
TL;DR: In this paper, the authors proposed the asymptotic presheath theory of the TEC and applied it to a time-dependent model of TEC in the program called TEC, which is not limited in applicability to TEC but is on interest to plasma-surface interactions in general.
Abstract: : The work on plasma presheaths, which form a transition region between the collisionless electrode sheaths and the plasma, is directed toward the problems of the Thermionic Energy Converter (TEC). A schematic of a TEC is shown in a reactor core for space power applications and the basic physics, Cesium is put the gap between the emitter and collector for two purposes: First, to ionize and neutralize the space charge so that a useful electron current density can pass (10 - 100 amps/square cm), and second to reduce the electrode work functions by adsorption fo cesium. Of the plasma physics of the cesium filled gap of the TEC, the plasma-electrode interactions are the most significant part because these regions form boundary conditions which control the plasma density and temperatures of the entire gap. Thus the research under this grant has been directed toward the study of collisional presheaths which form the layer adjacent to an electrode on the order of one ion mean free path thick. However, the research pursued under this grant is not limited in applicability to TECs but is on interest to plasma-surface interactions in general. Other applications include electric propulsion where electrode erosion is a problem and not fully understood and more generally any plasma-surface interaction. This report included the asymptotic presheath theory developed, and is preceded by the basic theory of the Thermionic Energy Converter (TEC) and is followed by the application of the theory to a time dependent model of the TEC in the program called TEC. As shown in the TEC results, the agreement with experiment is good except in the low current regime of the TEC where an unexplained disagreement remains. This is still a puzzle.

Journal ArticleDOI
TL;DR: In this paper, the authors derived analytic expressions connecting the three plasma parameters, namely hm, the height of the F2-peak; Nm, peak density and Ym, radius of curvature of the vertical profile at hm.

Proceedings ArticleDOI
06 Aug 1989
TL;DR: An experimental and theoretical investigation of the influence of molecular nitrogen additives on the volt-ampere characteristics of the diffusion mode and ignited mode in the interelectrode gap (IEG) of the thermionic energy converter (TEC) is reported in this article.
Abstract: An experimental and theoretical investigation of the influence of molecular nitrogen additives (P/sub N2/=10/sup -1//6*10/sup 2/ Pa) on the volt-ampere characteristics (VAC) of the diffusion mode and ignited mode in the interelectrode gap (IEG) of the thermionic energy converter (TEC) is reported. The experimental investigation was carried on a cylindrical TEC equipped with a system of dosed gas filling and pressure control. The processes in a Cs-N/sub 2/ plasma which cause the change of VAC of the thermionic converter were theoretically analyzed. It was found that the main process involved is the suppression of cesium atoms by nitrogen molecules. A theoretical model of a TEC with simple molecular gas additives was developed, and its VAC was calculated. The calculated VAC was in good agreement with experimental results for the various cases considered. >