Rotational analysis of the v6 band in furan (C4H4O)

SCOPUS: no.j

Signal restoration from band-pass filtered data

The restoration problem for a band-pass linear system is examined in the case the input signal is weighted by a profile function. The singular system is evaluated analytically for three different forms of the profile function. An example of restoration process is presented.

Dynamic analysis of Flip-Chip Self-Alignment

Self-alignment of soldered electronic components such as flip-chips (FC), ball grid arrays (BGA) and optoelectronic devices during solder reflow is important as it ensures good alignment between components and substrates. Two uncoupled analytical models are presented which provide estimates of the dynamic time scales of both the chip and the solder in the self-alignment process. These predicted time scales can be used to decide whether a coupled dynamic analysis is required for the analysis of the chip motion. In this paper, we will show that for flip-chips, the alignment dynamics can be described accurately only when the chip motion is coupled with the solder motion because the two have similar time-scale values. To study this coupled phenomenon, a dynamic modeling method has been developed. The modeling results show that the uncoupled and coupled calculations result in significantly different predictions. The calculations based on the coupled model predict much faster rates of alignment than those predicted using the uncoupled approach.

Optoelectronic packaging interfaces for submicron alignment (OPISA) and the dynamics of laser spot weld formation

The work presented in this paper is part of the OPISA project. This is a collaborative research project between the University of Greenwich and Bookham Technology. This report describes some of the initial work undertaken towards the goal of investigating optoelectronic packaging where alignment issues between optical sources and fibers can arise as part of the fabrication process. The focus of this study is on charting the dynamics of laser spot weld formation. This paper introduces some of the initial simulation work that has been undertaken and presents a model describing a transient heat source applied from a laser pulse to weld a stainless steel sleeve and ferrule and the resulting weld formation

Open ended microwave oven for flip-chip assembly

A novel open-ended waveguide cavity resonator for the microwave curing of bumps, underfills and encapsulants is described. The open oven has the potential to provide fast alignment of devices during flip-chip assembly, direct chip attach, surface mount assembly or wafer-scale level packaging. The prototype microwave oven was designed to operate at X-band for ease of testing, although a higher frequency version is planned. The device described in the paper takes the form of a waveguide cavity resonator. It is approximately square in cross-section and is filled with a low-loss dielectric with a relative permittivity of 6. It is excited by end-fed probes in order to couple power preferentially into the TM3,3,k mode with the object of forming nine 'hot-spots' in the open end. Low power tests using heat sensitive film demonstrate clearly that selective heating in multiple locations in the open end of the oven is achievable

Lundgreen, Peter unter Mitarbeit von Jürgen Schallmann: Die Lehrer an den Schulen in der Bundesrepublik Deutschland 1949-2009, Datenhandbuch zur deutschen Bildungsgeschichte, Band XI, Göttingen: Vandenhoeck & Ruprecht 2013 [...] [Sammelrezension]

Sammelrezension: 1. Lundgreen, Peter unter Mitarbeit von Jürgen Schallmann: Die Lehrer an den Schulen in der Bundesrepublik Deutschland 1949-2009, Datenhandbuch zur deutschen Bildungsgeschichte, Band XI, Göttingen: Vandenhoeck & Ruprecht 2013, (352 S.; ISBN 978-3-525-36388-5; 89,99 EUR) 2. András Németh / Ehrenhardt Skiera (Hrsg.): Lehrerbildung in Europa, Geschichte, Struktur und Reform, (Erziehung in Wissenschaft und Praxis; Bd. 9), Frankfurt am Main: Peter Lang 2012 (340 S.; ISBN 978-3-631-62454-8; 51,95 EUR)

Spatial Demultiplexing in the sub-millimeter wave band using multlayer free-standing frequency selective surfaces

In this paper, we show that a multilayer freestanding slot array can be designed to give an insertion loss which is significantly lower than the value obtainable from a conventional dielectric backed printed frequency selective surface (FSS). This increase in filter efficiency is highlighted by comparing the performance of two structures designed to provide frequency selective beamsplitting in the quasioptical feed train of a submillimeter wave space borne radiometer. A two layer substrateless FSS providing more than 20 dB of isolation between the bands 316.5â??325.5 GHz and 349.5â??358.5 GHz, gives an insertion loss of 0.6 dB when the filter is orientated at 45 incidence in the TM plane, whereas the loss exhibited by a conventional printed FSS is in excess of 2 dB. A similar frequency response can be obtained in the TE plane, but here a triple screen structure is required and the conductor loss is shown to be comparable to the absorption loss of a dielectric backed FSS. Experimental devices have been fabricated using a precision micromachining technique. Transmission measurements performed in the range 250â??360 GHz are in good agreement with the simulated spectral performance of the individual periodic screens and the two multilayer freestanding FSS structures.

Three-dimensional macroporous silicon photonic crystal with large photonic band gap

Three-dimensional photonic crystals based on macroporous silicon are fabricated by photoelectrochemical etching and subsequent focused-ion-beam drilling. Reflection measurements show a high reflection in the range of the stopgap and indicate the spectral position of the complete photonic band gap. The onset of diffraction which might influence the measurement is discussed.