| 1. |
- Payler, S.J., et al.
(författare)
-
Planetary science and exploration in the deep subsurface : results from the MINAR Program, Boulby Mine, UK
- 2017
-
Ingår i: International Journal of Astrobiology. - : Cambridge University Press. - 1473-5504 .- 1475-3006. ; 16:2, s. 114-129
-
Tidskriftsartikel (refereegranskat)abstract
- The subsurface exploration of other planetary bodies can be used to unravel their geological history and assess their habitability. On Mars in particular, present-day habitable conditions may be restricted to the subsurface. Using a deep subsurface mine, we carried out a program of extraterrestrial analog research – MINe Analog Research (MINAR). MINAR aims to carry out the scientific study of the deep subsurface and test instrumentation designed for planetary surface exploration by investigating deep subsurface geology, whilst establishing the potential this technology has to be transferred into the mining industry. An integrated multi-instrument suite was used to investigate samples of representative evaporite minerals from a subsurface Permian evaporite sequence, in particular to assess mineral and elemental variations which provide small-scale regions of enhanced habitability. The instruments used were the Panoramic Camera emulator, Close-Up Imager, Raman spectrometer, Small Planetary Linear Impulse Tool, Ultrasonic drill and handheld X-ray diffraction (XRD). We present science results from the analog research and show that these instruments can be used to investigate in situ the geological context and mineralogical variations of a deep subsurface environment, and thus habitability, from millimetre to metre scales. We also show that these instruments are complementary. For example, the identification of primary evaporite minerals such as NaCl and KCl, which are difficult to detect by portable Raman spectrometers, can be accomplished with XRD. By contrast, Raman is highly effective at locating and detecting mineral inclusions in primary evaporite minerals. MINAR demonstrates the effective use of a deep subsurface environment for planetary instrument development, understanding the habitability of extreme deep subsurface environments on Earth and other planetary bodies, and advancing the use of space technology in economic mining. Copyright © Cambridge University Press 2016
|
|
| 2. |
- Xu, Fei, et al.
(författare)
-
Fatigue Life Prediction for PBGA under Random Vibration Using Updated Finite Element Models
- 2016
-
Ingår i: Experimental techniques (Westport, Conn.). - : Springer. - 0732-8818 .- 1747-1567. ; 40:5, s. 1421-1435
-
Tidskriftsartikel (refereegranskat)abstract
- A procedure based on finite element (FE) modeling, response surface-based model updating and random vibration analysis is presented to predict the fatigue life of plastic ball grid array (PBGA) components mounted on daisy chain printed circuit board (PCB). A specially designed fixture is used to mimic the typical boundary condition of plug-in PCBs. The FE model is updated through three consecutive stages. In each stage, the first three resonant frequencies are calculated using ANSYS and correlated with modal test results. Two objective functions are created using resonant frequencies and minimized using a multi-objective genetic algorithm (MOGA). The results show that commercial FE software can be used to improve the accuracy of the FE model in a practical way. Random vibration analysis is performed and good agreement with test result is obtained. The resistance of the specially designed daisy chain PCB is monitored. A two-parameter Weibull distribution is used to fit the PBGA failure time. The Von Mises stress power spectral density (PSD) of the critical solder joints is calculated in ANSYS and transferred into time-history data. The rainflow cycle counting (RFCC), the S–N curve and the Miner’s rule are used to estimate the cumulative damage. The calculated fatigue life agrees well with the test results.
|
|
