Fatigue,residual strength and non-destructive tests of an aging aircraft’s wing detail

This study concentrates on fatigue, residual strength and non-destructive tests of an aging aircraft’s wing detail of the Finnish Air Force’s Hawk Mk.51 jet trainer. The studied detail was the integral stiffener with a drain hole near the wing root. Fatigue tests were deemed necessary to verify experimentally the analytically observed short fatigue life, significant crack growth rates and eventually to re-assess the detail’s inspection period for the fleet jets. The results of the study have been utilized e.g. at the complementary type approval accomplished for the Finnish Air Force’s Hawk.     

Radiation monitoring strategy: factors to be considered

In a nuclear or radiological emergency radiation measurements provide indispensable data needed in the management of the situation at hand. In order to assess the possible consequences correctly and to carry out proper countermeasures on time, the authorities must have a pre-prepared monitoring strategy at their disposal. There are, however, many different factors that affect a strategy. Thus, drawing up a comprehensive yet realistic emergency monitoring strategy is far from being an easy task. Some of the key factors related to strategies are reviewed and a simple way of producing a strategy plan is presented.     

Bonded thick film SOI with pre-etched cavities

We have studied direct bonding and thinning of pre-etched silicon wafers. Silicon-on-insulator (SOI) substrates with pre-etched cavities provide freedom to MEMS design and enable manufacturing of advanced sensor structures (sensor structures that would be difficult or impossible with conventional substrates). Cavities with different shapes and sizes were etched on to the handle wafers. The etched handle wafers were bonded to unpatterned cap wafers in air or in vacuum. The bonding quality was evaluated with scanning acoustic microscopy and with HF-etching test. After bonding, the cap wafers were thinned down with grinding and polishing. The thickness variation of silicon diaphragm over the cavities was evaluated with cross-sectional SEM. The deflection of the Si film was measured with surface profilometry. To decrease the deflection and the thickness variation of the film, different support structures were placed inside the cavities.The bonding experiments carried out with patterned wafers showed that vacuum bonding results in slightly higher bonding energy than bonding in air. With large cavity fraction (80% of total wafer area), the air bonded samples had large void on the bonded interface. With smaller cavity fractions or with vacuum bonded samples, no such voids were found. Thinning studies showed that the thickness variation of the silicon diaphragm increases with increasing cavity dimensions and with decreasing SOI layer thickness. Thickness variation can be reduced with support structures under the Si membrane.     

Daylight optimization of multifunctional solar facades

Multifunctional solar facades consisting of a transparent window and an opaque photovoltaic section are analyzed and optimized. Employing numerical daylight estimation techniques, the optimal shape, position, and area of the window section is determined. Maximum yearly average daylight availability is achieved with a similarly shaped window as the facade which is placed near the centre of the facade. For non-residential buildings, the yearly average useful interior daylight illuminance does not increase significantly for windows larger than 30% of the total facade area. Considering both the artificial lighting requirement replaced by daylight through the window and the electricity produced by the PV section of the facade, the maximum electricity benefit for a south-facing facade is achieved with a window area of about 10% of the total facade area in Southern Europe (38° N) and 15% in Northern Europe (60° N).     

A robust method for image stitching

Pattern Analysis and Applications - We propose a novel method for large-scale image stitching that is robust against repetitive patterns and featureless regions in the imagery. In such cases,...     

Nanocrystalline WC-Co HVAF Coatings by Utilizing Novel Powder Manufacturing Route Using Water-Soluble Raw Materials

In this study, nanostructured WC-Co coatings were produced using experimental nanocrystalline WC-12Co and WC-24Co powders produced by a novel chemical synthesis route. Test coatings were produced using HVAF spraying keeping the temperature as low as possible during the deposition in order to avoid decomposition of the nanocarbides. In experimental powders, two different Co incorporation methods were used: a conventional way in which cobalt was incorporated as a metallic Co powder and a chemical synthesis way in which cobalt acetate was used as a cobalt source. When using cobalt acetate, it decomposes to metallic cobalt during the process. Experimental powders in which cobalt acetate has been used as cobalt source resulted poor deposition efficiency. With warmer parameters, powders resulted better DE, but significant WC decarburization and the dissolution into the matrix phase occurred. Powders in which Co has been introduced as Co powder showed enhanced DE enabling spraying with decreased temperature and higher particle velocity, resulting in coatings with less WC decomposition. Especially, an experimental powder in which Co has been incorporated both as Co powder and as Co-Ac results very fine nanocarbide structure with significantly less WC decomposition having a hardness value of 1201 HV0.3, even with 24% Co.     

The Effect of Sulphur and Water Treatments on the Performance of Pd/��-Zeolite Diesel Oxidation Catalysts

Sulphur, sulphur-water, and water pretreatments were done to find out the effect of these compounds on a diesel oxidation Pd/??-zeolite catalyst and ??-zeolite washcoat. After pretreatments, the samples were analysed by BET, XRF, TEM-SEM, and XPS. In addition, the activity of fresh and pretreated Pd/??-zeolite catalysts was studied utilizing the by Gasmet FT-IR in production gas analysis. Sulphur compounds (SO₂ or ?SO₄) were found to have a deactivating effect on the activity of the studied Pd/??-zeolite catalyst.     

Comparison of analog continuum correlators for remote sensing andradio astronomy

Two different designs of analog correlators for radiometry are compared in this paper. A continuum correlator based on a microwave nonlinear device is a simple and inexpensive way to detect wide-band polarized signals. Analysis and extensive measurements including linearity, dynamic range, amplitude response, phase balance, and stability are presented, and the suitability of the designs for microwave radiometry is discussed. Both correlators showed nearly ideal performance. A novel method for determining the correlator degradation factor is applied     

争论-分析-评价：一种运用于战略规划的手段

赫尔辛基科技大学结合若干研究项目，开发了一种在规划过程中自始自终运用“争论-分析-评价”的方法。争论理论在许多研究领域得到普遍运用，特别是在20世纪50年代流行以来得到了更大的发展。虽然这种方法尚未经过实际规划过程的检验，但它已经被运用在规划文件的后期评价中。本文对这种方法的理论基础进行了阐述。