A new method of studying the accelerated ageing of interconnection materials is applied to a high‐stability thick film resistor system (the Du Pont HS‐80 system). The new…
A new method of studying the accelerated ageing of interconnection materials is applied to a high‐stability thick film resistor system (the Du Pont HS‐80 system). The new method, referred to hereafter as the in‐situ method, allows measurement of the electrical resistance of a thick film resistor to a resolution of a few ppm during accelerated ageing. With the in‐situ technique, the electrical resistance measurements are performed at the elevated ageing temperature during the ageing treatment, whereas with the conventional ageing method the resistance measurements are carried out at room temperature, between subsequent annealing steps. The measuring resolution obtainable with the in‐situ method is orders of magnitude better than with the conventional method. The ageing kinetics can therefore be studied on a shorter time scale and in greater detail than with the conventional method. In this paper, the authors use the in‐situ method to study the accelerated ageing of the Du Pont HS‐80 thick film resistor system, encapsulated with a proper glaze. It will be shown that kinetics of the resistance drift observed in this system cannot be described by an Arrhenius‐type equation. The ageing data can only be interpreted in terms of a kinetic model incorporating a spectrum of activation energies for the ageing process. Such a model is given, and is shown to provide a good explanation of the observed ageing behaviour. The physical process that causes the observed ageing is most probably diffusion of silver from the contacting terminals into the amorphous matrix of the thick film resistor.
Presents the influence of rheological properties of a sewing thread on its dynamical loads in a stitch formation process, or on change of thread strength as a consequence…
Presents the influence of rheological properties of a sewing thread on its dynamical loads in a stitch formation process, or on change of thread strength as a consequence of dynamical loads in the sewing process, respectively. Research work shows the change in thread strength, as a result of the stitch formation process forming dynamic loads of a thread, as a function of rheological properties of a thread.
Artificial automata replace, in part or in total, natural automata in systems, and properly disciplined models of natural automata become design models of artificial…
Artificial automata replace, in part or in total, natural automata in systems, and properly disciplined models of natural automata become design models of artificial automata for replacement. In Part I, a summary of two sets of disciplines provided by a General Systems Theory is presented, and the importance of these disciplines to the modeling of three inherited abilities is indicated for a case study. A theorem is presented in the form of an algorithm to aid in the modeling of the ability to modify and extend knowledge structures. In Part II (appearing in the next issue), the proof of the theorem is given and the theorem is applied to the case study. Finally, the application of the disciplines of the General Systems Theory is indicated for a second casestudy of an industrial system of 10 interactive automata.
A cybernetic theory of hierarchical social systems is given, starting from an extension of Ashby's general theory of regulation and control to amplifying regulation. Regulation and control in human society are then discussed and the conditions for the existence of social classes and social hierarchy examined.
To prolong engine life and reduce exhaust pollution caused by gasoline engines, the aim of this paper was to compare the lubrication properties of biofuel (ethanol) blends…
To prolong engine life and reduce exhaust pollution caused by gasoline engines, the aim of this paper was to compare the lubrication properties of biofuel (ethanol) blends and pure unleaded gasoline.
Biofuels with a concentration of 0, 1, 2, 5 and 10 per cent were added to unleaded gasoline to form ethanol-blended fuels named E0, E1, E2, E5 and E10. Next, the ethanol-blended fuels and unleaded gasoline were used to power engines to facilitate comparisons between the pollution created from exhaust emissions.
Using ethanol as a fuel additive in pure unleaded gasoline improves engine performance and reduces exhaust emissions. Because bioethanol does not contain lead but contains low aromatic and high oxygen content, it induces more complete combustion compared with conventional unleaded gasoline.
Using biofuels as auxiliary fuel reduces environmental pollution, strengthens local agricultural economy, creates employment opportunities and reduces demand for fossil fuels.
This brief paper considers the various possible mathematical operations on fuzzy sets that are required to implement a set of control rules as a fuzzy logic control element. The influence that these operations have on the characteristics of the final control element is a factor that is used to select those operations most suitable in the control context.
The first half In the first part (March) the idea was introduced of the metal adopting an electrical potential when it is placed in a solution. This happened because some…
The first half In the first part (March) the idea was introduced of the metal adopting an electrical potential when it is placed in a solution. This happened because some of the metal atoms went into the solution forming positively charged particles called ions, and leaving behind electrons in the metal. In shorthand notation:
Calculations have been carried out on two elliptic wings, with ratios of major to minor axis 2·5 and 5 to 1 respectively, in order to demonstrate the use of vortex…
Calculations have been carried out on two elliptic wings, with ratios of major to minor axis 2·5 and 5 to 1 respectively, in order to demonstrate the use of vortex lattice theory in calculating lr and nr by lifting plane theory for wings of arbitrary plan form. Special tables of downwash, required in order to allow for the curvature of the wake, are included, and the origin of the formulae by which these are derived in a form applicable to linear theory is fully described. For the first wing, the calculated results for lr and nr and for local aerodynamic centre, load coefficients, and local lift coefficients are given for the Glauert‐Wieselsberger lifting line solution as well as for lifting plane solutions with three, six and nine control points respectively. The main work on the second wing is concerned with a six‐point lifting plane solution. The results show that there is not a serious difference between lifting line and lifting plane theory, excepting that the former does not give reliable values for the local a.c. For straight wings the six‐point lifting plane solution gives excellent accuracy. The method is applicable to wings of arbitrary plan, but the field of sweptback wings is unexplored and it should not be assumed without check that the relation of accuracy to number of control points is always the same. A further investigation is also required on the formula for nr when sweepback is present. The calculated value of lr for the 5 to 1 elliptic wing is in close agreement with the measured value for this wing obtained by Wieselsberger on a whirling arm. The report is concerned mainly with the calculation of spanwise load grading and local aerodynamic centre, and extension to detailed pressure distribution may require the use of more variables.