| 1. |
- Borgström, Henrik, 1975, et al.
(författare)
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Possibilities and constraints of implementing starch consolidated high speed steel in prototyping
- 2008
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Ingår i: Materials Science & Engineering. - : Elsevier BV. - 0921-5093 .- 1873-4936. ; 475:1-2, s. 34-38
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Tidskriftsartikel (refereegranskat)abstract
- In the starch consolidation (SC) process, a water-based slurry containing powder, starch, dispersant and thickener is used to fabricate near net-shape green bodies that are de-binded and further consolidated by sintering. In this study, gas atomized M3/2 as well as high and low carbon V-rich M4 type high speed steel powder (<150 mu m) are considered, Both material types undergo high volumetric shrinkage during super-solidus liquid phase sintering enabling them to reach near full density. The analyses and the review cover different process aspects like: recipe optimisation, post-gelatinization drying, de-binding and sintering. A SC recipe consisting of 58 vol.% powder, 3 vol.% starch, 1 vol.% dispersant and a thickener solution resulted in a density of >98% than what is theoretically stated after sintering. It is found that the success of the post-gelatinization drying procedure depends on the smoothness of mould material and controlling powder oxidation. The best combination was freeze drying the slurry in a silicon rubber mould. For V-rich alloys a total or partial control of eutectic carbides in the final microstructure could be realized for vacuum and nitrogen sintering atmospheres, respectively.
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| 2. |
- Nafari, Alexandra, 1980, et al.
(författare)
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MEMS Sensor for in Situ TEM Atomic Force Microscopy
- 2008
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Ingår i: Journal of microelectromechanical systems. - : IEEE Press. - 1057-7157 .- 1941-0158. ; 17:2, s. 328-333
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Tidskriftsartikel (refereegranskat)abstract
- Here, we present a MEMS atomic force microscope sensor for use inside a transmission electron microscope (TEM). This enables direct in situ TEM force measurements in the nanonewton range and thus mechanical characterization of nanosized structures. The main design challenges of the system and sensor are to reach a high sensitivity and to make a compact design that allows the sensor to be fitted in the narrow dimensions of the pole gap inside the TEM. In order to miniaturize the sensing device, an integrated detection with piezoresistive elements arranged in a full Wheatstone bridge was used. Fabrication of the sensor was done using standard micromachining techniques, such as ion implantation, oxide growth and deep reactive ion etch. We also present in situ TEM force measurements on nanotubes, which demonstrate the ability to measure spring constants of nanoscale systems.
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| 3. |
- Brzezinski, Juliusz, 1939, et al.
(författare)
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Smooth lattices over quadratic integers
- 2008
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Ingår i: Mathematische Zeitschrift. - : Springer Science and Business Media LLC. - 1432-1823 .- 0025-5874. ; 258:1, s. 161-184
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Tidskriftsartikel (refereegranskat)abstract
- We construct lattices with quadratic structure over the integers in quadratic number fields having the property that the rank of the quadratic structure is constant and equal to the rank of the lattice in all reductions modulo maximal ideals. We characterize the case in which such lattices are free. The construction gives a representative of the genus of such lattices as an orthogonal sum of "standard" pieces of ranks 1-4 and covers the case of the discriminant of the real quadratic number field congruent to 1 modulo 8 for which a general construction was not known. © 2007 Springer-Verlag.
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| 4. |
- Larson, Ulf, 1975, et al.
(författare)
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Operator-Centric and Adaptive Intrusion Detection
- 2008
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Ingår i: Proceedings of the Fourth International Conference on Information Assurance and Security (IAS 2008), September 8-10, 2008, Naples, Italy. - Naples, Italy : IEEE. - 9780769533247 ; , s. 161-166
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Konferensbidrag (refereegranskat)abstract
- An intrusion detection system should support the operator of the system. Thus, in addition to producing alerts, it should allow for easy insertion of new detection algorithms. It should also support dynamic selection and de-selection of detection algorithms, and it should adjust its resource consumption to the current need. Such a system would allow the operator to easily extend the system when new detection algorithms become available. It would also allow the operator to maintain a low-cost monitoring baseline and perform more extensive monitoring when it is required. In this paper we propose an architecture for intrusion detection which aims at providing the operator with this support. The architecture uses a modular design to promote a high degree of flexibility. This supports creation of an environment in which state-of-the-art intrusion detection algorithms easily can be inserted. The modular design also allows for detection algorithms to be enabled and disabled when required. Additionally, the architecture uses a sensor reconfiguration mechanism to affect the amount of data collected. When a detection algorithm is enabled or disabled, the sensor providing the input data to the algorithm is correspondingly reconfigured. This implies a minimum of excess collected data. To illustrate the feasibility of the architecture, we provide a proof - of-concept supporting monitoring of users for insider detection and webserver monitoring for intrusion attempts
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| 5. |
- Watcharinyanon, Somsakul, 1978-, et al.
(författare)
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A spectroscopic study of self-assembled monolayer of porphyrin-functionalized oligo(phenyleneethynylene)s on gold : the influence of the anchor moiety
- 2008
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - London : RSC Publishing. - 1463-9076 .- 1463-9084. ; 10:34, s. 5264-5275
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Tidskriftsartikel (refereegranskat)abstract
- Porphyrin-functionalized oligo(phenyleneethynylene)s (OPE) are promising molecules for molecular electronics applications. Three such molecules (1-3) with the common structure P-OPE-AG (P and AG are a porphyrin and anchor group, respectively) and different anchor groups, viz. an acetyl protected thiol, -S-COCH3 (1), an acetyl protected thiol with methylene linker, -CH2-S-COCH3 (2), and a trimethylsilylethynyl group, -C(triple bond)C-Si(CH3)3 (3) have been synthesized and the corresponding self-assembled monolayers (SAMs) on Au(111) substrates have been prepared. The integrity and structural properties of these films were studied by X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy. The results suggest that the films formed from 1 have a high orientational order with an almost upright orientation and dense packing of the molecular constituents, i.e. represent a high quality SAM. In contrast, molecule 2 formed disordered molecular layers on Au, even though the molecule-surface bonding (thiolate) is the same as in the case of molecule 1. This suggests that the methylene linker in molecule 2 has a strong impact on the quality of the resulting film, so that a well-ordered SAM cannot be formed. The silane system, 3, is also able to bind to the gold surface but the resulting SAM has a poor quality, being significantly disordered and/or comprised of strongly inclined molecules. The above results suggest that the nature of the anchor group along with a possible linker is an important parameter which, to a high extent, predetermines the entire quality of OPE-based molecular layers
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| 6. |
- Bohlin, Christina, 1979-, et al.
(författare)
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Diastereomer selectivity in the degradation of a lignin model compound of the arylglycerol β-aryl ether type by white-rot fungi
- 2008
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Ingår i: Enzyme and Microbial Technology. - : Elsevier BV. - 0141-0229 .- 1879-0909. ; 43:2, s. 199-204
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Tidskriftsartikel (refereegranskat)abstract
- Mixtures of about equal amounts of the diastereomers of arylglycerol β-aryl ether 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)-1,3-propanediol (1) were added to cultures of Trametes versicolor, Phanerochaete chrysosporium, and Pycnoporus cinnabarinus. Samples taken from the fungal cultures were analyzed with respect to the fraction of 1 degraded, the erythro:threo ratio in the remaining 1, and the product profile, using HPLC and UV-diode array detector. The P. cinnabarinus cultures exhibited laccase activity and partially decolorized Remazol Brilliant Blue R (RBBR), but they did not degrade 1 under the conditions studied. Cultures of T. versicolor and P. chrysosporium preferentially degraded the threo isomer of 1. This is consistent with the fact that the product profiles showed larger amounts of threo- than erythro-veratrylglycerol. The results can be discussed in relation to the diastereomer selectivity of various oxidants implicated in lignin degradation by white-rot fungi. Preferential degradation of the threo isomer of arylglycerol β-aryl ethers is not in agreement with the action of Fenton's reagent, since this reagent does not exhibit any stereopreference.
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| 7. |
- Larson, Ulf, 1975, et al.
(författare)
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A Revised Taxonomy of Data Collection Mechanisms with a Focus on Intrusion Detection
- 2008
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Ingår i: Proceedings of the Third IEEE International Conference on Availability, Reliability and Security (ARES 2008). - Barcelona, Spain : IEEE. - 9780769531021 ; , s. 624-629
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Konferensbidrag (refereegranskat)abstract
- Surprisingly few data collection mechanisms have been used for intrusion detection, and most systems rely on network and system call data as input to the detection engine. Even though the quality of log data is vital to the detection process and heavily dependent on the collection mechanism, no extensive survey or taxonomy has been conducted within the detection field. In this paper, we propose a revised taxonomy which provides a unified terminology and a framework in which data collection mechanisms can be systematically inspected, evaluated, and compared. Since the taxonomy is derived from existing mechanisms, it also provides a useful overview of different types of mechanisms. The paper also suggests areas within data collection where additional work is required.
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| 8. |
- Larson, Ulf, 1975, et al.
(författare)
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Decision Support for Intrusion Detection Data Collection
- 2008
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Ingår i: Proceedings of the 13th Nordic Workshop on Secure IT-systems (NordSec 2008), October 9-10, 2008, Copenhagen, Denmark. - Copenhagen, Denmark.
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Konferensbidrag (refereegranskat)abstract
- Data collection is a critical but difficult activity forintrusion detection. The amount of resources that must be monitored and the rate at which events are generated makes it impossible to use an exhaustive collection strategy. Furthermore, selection and configuration of data collection mechanisms is a tedious and elaborate task for both designers and operators. Therefore, we propose a decision support system (DSS) for selecting and configuring datacollection mechanisms. We suggest a generic system model for selecting data collection mechanisms based on the amount of excess data produced. We also provide an implementation of the system. The DSS reduces effort, time, and expertise required in the selection process, and allows both designers and operators to focus on intrusion detection rather than selection and configuration of data collection mechanisms.
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