CITATION: Craig, O O., Dobson, R. T. & Van Niekerk, W. 2017. A Novel Indirect Parabolic Solar Cooker. Journal of Electrical Engineering, 4:137-142, doi:10.17265/2328-2223/2017.03.003.

This paper discusses issues regarding the operation of algorithms for VoIP (voice over internet protocol) signaling. The resulting data include jitter, packet delays, delays related to signalization, distribution of packets in protocols and relative assessments of QoS (quality of service) and MOS (mean opinion score).

This study compares experimentally determined and simulated mechanical strength of different geometries laser cut into alumina ceramic substrates. A digital power modulated 500 W single mode fiber laser is used to cut differently shaped inner contours into rectangular ceramic substrates. The flexural strength of these samples is measured by a 3-point-bending test. In addition, employing a finite element simulation the principal stress of these geometries during a 3-point-bending is simulated with a linear elastic model. The reciprocal of the simulated stress is compared with the measured strength revealing an excellent agreement. We, therefore, can conclude that the strength reduction by cutting inner contours can be exclusively explained by the geometry of the rectangular, which in turn implies that the fiber laser cutting process itself causes no relevant additional structural damage. These results highlight the superior quality of digital power modulated fiber laser cutting of ceramics. Moreover, we demonstrate by a further comparison between experimental and simulated results that an increased strength is feasible by displacing fragile parts of inner contours to areas with less mechanical load.

Semiconductors are running in Moore's beat bringing out impressively small processor, memory, amplifier and sensor chips. However, their packaging is more often the challenge for developers and system designers. The paper describes requirements and solutions for two advancing 3D chip packages. The first application is a request for a magnetic field sensor in the narrow gap between rotor and stator of electric motors under the influence of temperature, axial and radial load. This LTCC multilayer providing twisted pair wiring and stepped cavities including a lowered bond shelf is 200 microns thin. The second one is a challenging package for a space component with a 7 layer stepped cavity. It enables multi level wire bonding to the <50μm pitch of the detector chip. Beside the large chip the package is carrying multiple soldered or adhesive bonded chips and passive components, the flex and a robust LGA connector. Further reasons for the choice of LTCC were stiffness, high reliability expectations and thermos-mechanical matching to silicon under space conditions.

Electrical properties and crystal perfection of undoped and n-type heavily arsenic-doped the Si-rich SiGe alloys bulk single-crystals were investigated. Influence of Ge atoms and doping by As on electrical properties and crystal perfection of SiGe alloys in the composition range 0-3at%Ge are reported. It was established, that carriers mobility in heavily impurity doped n-type Si-rich SiGe alloys is significantly lower, than in undoped alloys. It does not depend on the Ge concentration and is defined by carriers scattering upon impurity ions. It was established, that Ge atoms do not scatter as neutral centers. The mobility, related to the carriers scattering upon Ge atoms, can be explained in terms of "alloy" scattering. Investigation has shown that increasing of Ge content in Si increases dislocations density and disturbs their homogeneous distribution. The disturbance of homogeneous distribution of dislocations increases with increasing of Ge concentration. But dislocation structure is not revealed in heavily doped n-SiGe alloy crystals. Thus dilute heavily impurity-doped with arsenic SiGe alloys are similar to impurity-doped n-Si.

This paper presents the mathematical basis, and some results, concerning the application of the Haar Wavelets as the expansion function in the Method of Moments. As an example, the surface charge density on a finite, thin plane plate, and the Eddy current problem, in which the main computational performance aspects are evaluated. Some computational optimization techniques are used, and their main aspects are stressed in the paper.