Showing papers by "Delft University of Technology published in 1970"

Projection masking, thin photoresist layers and interference effects

Abstract: Projection masking is used for producing microwave semiconductor devices with micrometer or submicrometer structures. In contrast to contact masking, the mask is projected onto the silicon wafer by means of a high quality microscope objective. Since the chromatic errors of such a lens cannot be fully corrected, monochromatic light has to be employed. This, however, causes standing light waves to occur in the SiO2 and photoresist layers, leading to unexpected effects. This report describes some of these effects and the experimental conditions under which satisfactory masking results can be obtained.

Pseudo-random binary sequences for multiplex codes.

Abstract: A multiplex technique is described that can be used in photoelectric observations of dispersed spectra. The encoding pattern is a set of pseudo-random binary sequences. The data processing requires a minimum possible number of operations. A special purpose device could give the spectral intensity distribution on-line. An application at the solar eclipse (Mexico, 1970) is described.

Isolation and characterization of two vibrio-shaped methane-oxidizing bacteria.

Abstract: An enrichment method for, and the isolation of two related vibrio-shaped methane-oxidizing bacteria are described. Their morphological and physiological characteristics are given. As a name for the genus of the organisms “Methy lovibrio” is proposed.

The Shuman filtering operator and the numerical computation of shock waves

Abstract: Shuman's method of filtering short-wave components is discussed. In certain cases, this method can be used to prevent nonlinear instabilities in numerical calculations. As illustrative example, the computation of a detached shock in front of a blunt body is considered.

Metallization processes in fabrication of Schottky-barrier FET's

Abstract: The metallization processes necessary for the production of microwave Schottky-barrier field-effect transistors are described. Since the gate contact is only 1 micrometer wide, the holes and the metallization of the source, drain and gate contacts are produced simultaneously. Then in a subsequent process,the source and drain contacts are converted to ohmic contacts by the evaporation of Au-Sb onto these contacts. Mask alignment is not a problem because the Au-Sb spreads across the surface after suitable heat treatment.

DDT: its action and degradation in bacterial populations.

Abstract: A POSSIBLE example of a bacterial population adapted to DDT has been reported by Henzell and Lancaster1, who demonstrated a 50 per cent conversion of DDT in silage. In the study I report here, soil and water microflora were examined for DDT-accumulating, DDT-resistant, DDT-sensitive and DDT-degrading microbes.

A quantum mechanical treatment of the mirror electron microscope

Abstract: A wave mechanical description of the electron beam in a mirror electron microscope is given. First the Schrodinger equation of the electron beam is set up, from which the wave function is obtained. Then the probability current density is derived, which turns out to be a useful expression to clarify the formation of the image on the screen.

An apparatus for the continuous cultivation of sulfate-reducing bacteria and its application to geomicrobiological purposes.

Abstract: An apparatus for the continuous cultivation of sulfate-reducing microorganisms is described. The characteristics of the continuous process are discussed and a brief description is given of an iron-sulfide mineral formed in this bacteriological process.

Experimental Calibration Of A Viscoplastic-Fracturing Computational Model

Abstract: An extensive experimental and analytical investigation is currently being carried out on the mechanisms leading to the initiation and propagation of damage in viscoplastic materials. One of the major goals of the investigation is the development and the finite elements implementation of a generalised triaxial, strain rate sensitive, history and temperature dependent constitutive model. Explicit procedures have been formulated for the experimental determination of the model parameters. As a minimum, only uniaxial test results are needed for determination of the basic parameters. The model has been implemented in the finite element code CAPA-3D. Results of the utilization of CAPA-3D for the investigation of the dynamic non-linear response of a road pavement are reviewed in the last part of this contribution.

Changing public port management in the Hamburg-Le Havre range

Abstract: Recent trends in trade liberalisation and globalisation of the world economy have a significant impact on seaborne trade and ports. As a results of these developments, the traditional view on public port management is changing. In the paper recent and anticipated developments in public port management in the Hamburg - Le Havre range are examined. The classification refers mainly to formal aspects and shows a wide variety in public port management. A closer look at the real situation shows differences in port policy even within the same institutional setting. So, the diversity in public port management not only concerns the institutional factors but also the pursued port policy. Additionally, the (future) European sea port policy is described. The purpose of the newly published Green Paper on Sea Ports and Maritime Infrastructure by the European Commission, is launching a wide ranging debate on individual port issues and possible future policies. At the heart of this policy lies the introduction of market principles in infrastructure and the development of a uniform approach to ensuring that the full costs are charged to the users. Ultimately, a situation of free and fair competition must be achieved. The paper shows that a shift towards greater private participation in port activities, in particular those of a commercial nature, is already evident.

Solution of state-constrained optimal control problems through quasilinearization

Abstract: Quasilinearization is extended to the numerical solution of multi-point boundary-value problems for ordinary differential equations. It is described how such problems arise from state-constrained optimal control problems. A simple numerical example is given to illustrate the method.

Enhancing Process Visibility of the Supply Chain ‘Data Pipeline’

Abstract: Although business process visibility is considered to be increasingly important for international trade, the visibility of existing supply chains is currently still ambiguous. Information deficiencies such as incorrectness or inconsistency of data are major determinants that decrease clarity. The Data Pipeline principle has been proposed to overcome the data quality shortcomings, enhance the visibility, and improve performance of the supply chain. In a first elaboration, the Data Pipeline model named the Distributed Trust Backbone (DTB) was designed and implemented in three different countries. In order to discover the effectiveness and feasibility of the model, the visualization of the Data Pipeline’s process flow is urgently required in terms of both real-time detection of system failures and process flow representations. However, there is no process visualization feature available for the Data Pipeline. This challenge is taken up in this paper. We propose a Data Pipeline monitoring system and describe the results of performed simulation tests based on a case study of the international trade lane between Southeast Asia and Europe.

Design of a probe microphone

Abstract: Measuring a fluctuating pressure at a discrete point in an air flow requires a narrow probe connected by a transmission tube (of arbitrary length) to the membrane chamber of a microphone. A correct transmission of the pressure in the tube is achieved by a special construction of the chamber giving the tube the characteristic specific acoustic impedance at its terminal. The chamber is accordingly shunted to the ambient atmosphere by a narrow slit; the effect of the inertia of the slit is balanced by the capacity of the chamber, the resistance constitutes the required real impedance.

On Sensitivity and Detection Limit with Reference to Flame Spectrometry

Abstract: Apparently and amazingly, the concepts of sensitivity and detection limit are still a matter of debate among flame spectroscopists. Probably the papers on this issue by Willis1 and West2 and certainly some misleading statements would have been left unwritten, if these authors had taken the elementary precaution of consulting the pertinent literature3-7 or an appropriate textbook8. Surely there is no need to resort to “normal English usage”2 when discussing well-defined scientific concepts. No doubt, most of the confusion stems from the fact that the pioneering articles have been written in German and from the lack of a consistent English, terminology. One frightening example is offered by Ramirez-Munoz9 who introduces no less than sixteen different terms, freely interchanging sensitivity and detection limit. But perhaps, it is not too late to restore the damage.