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See detailOptimality Results on the Security of Lookup-Based Protocols
Mauw, Sjouke UL; Toro Pozo, Jorge Luis UL; Trujillo Rasua, Rolando UL

in Hancke, Gerard P.; Markantonakis, Konstantinos (Eds.) Radio Frequency Identification and IoT Security - 12th International Workshop, RFIDSec 2016, Hong Kong, China, November 30 - December 2, 2016, Revised Selected Papers (2016, December)

Distance-bounding protocols use the round-trip time of a challenge-response cycle to provide an upper-bound on the distance between prover and verifier. In order to obtain an accurate upper-bound, the ... [more ▼]

Distance-bounding protocols use the round-trip time of a challenge-response cycle to provide an upper-bound on the distance between prover and verifier. In order to obtain an accurate upper-bound, the computation time at the prover’s side should be as short as possible, which can be achieved by precomputing the responses and storing them in a lookup table. However, such lookup-based distance bounding protocols suffer from a trade-off between the achieved security level and the size of the lookup table. In this paper, we study this security-memory trade-off problem for a large class of lookup-based distance bounding protocols; called layered protocols. Relying on an automata-based security model, we provide mathematical definitions for different design decisions used in previous lookup-based protocols, and perform general security analyses for each of them. We also formalize an interpretation of optimal trade-off and find a non-trivial protocol transformation approach towards optimality. That is to say, our transformation applied to any layered protocol results in either an improved or an equal protocol with respect to the optimality criterion. This transformation allows us to provide a subclass of lookup-based protocol that cannot be improved further, which means that it contains an optimal layered protocol. [less ▲]

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See detailOptimally Combining Censored and Uncensored Datasets
Devereux, Paul J.; Tripathi, Gautam UL

in Journal of Econometrics (2009), 151

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See detailOptimierung auf der Energiesynchronisationsplattform: Teil der Reihe Diskussionspapiere V4 Konzept der Energiesynchronisationsplattform
Schlip, Johannes; Bank, Lukas; Köberlein, Jana et al

Report (2021)

This discussion paper is intended to present the range of optimisers developed in the SynErgie project and to go into more detail on the methodological aspects. In this discussion paper, a distinction is ... [more ▼]

This discussion paper is intended to present the range of optimisers developed in the SynErgie project and to go into more detail on the methodological aspects. In this discussion paper, a distinction is made between optimisers on the company platform and on the market platform. On the company platform, the goal is to ensure optimal operation of the plants, so that in addition to energy, other operational key figures are included in the analysis. These include various optimisers from production planning and control (PPC), which, in addition to energy costs, also track logistical target variables, such as the on-time delivery of products, as key figures. In addition to the production systems, the facilities of the technical building equipment (TGA) are also optimised on the company platform. Furthermore, within the discussion paper, we differentiate between energy-oriented and energy-flexible optimisation. Energy-oriented optimisation, pursues the goal of minimise energy costs, uses information from the energy markets, such as electricity price forecasts. With flexible optimisation, for example, flexibilities are determined or scheduled, which can then be transmitted to the market. The discussion paper also deals with the optimisation services of the optimisation services of the market platform, which determines the optimal marketing opportunity for the determined. The optimiser calculates the optimal time for different markets in order to maximise the proceeds of the maximise the revenue of the flexibility offered or minimise the costs. Should a flexibility provider decide to use a service to take over the marketing of his flexibility measure, information on the flexibility is transmitted between the flexibility is transmitted between the service and the company in order to be able to implement the measure in the company. [less ▲]

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See detailOptimierung der Wickelgüte in der Spinnvliesproduktion mit Fuzzy Control
Voos, Holger UL; Hartel, Harald; Schmitt, Peter

in Automatisierungstechnische Praxis (1999), 41(6), 48-54

This work introduces a new control concept for a re-winder in the spunweb production. The rewinder serves to cut the spunweb-rolls into several rolls of customer-specified width. High customer demands ... [more ▼]

This work introduces a new control concept for a re-winder in the spunweb production. The rewinder serves to cut the spunweb-rolls into several rolls of customer-specified width. High customer demands toward roll quality were, so far, only met unsatisfactorily with PID control of the web-tension. The newly developed control concept uses fuzzy control. It provides a modular design and is specifically adjusted to the different states of the machine that occur during production. It was proven that this concept rapidly increases roll quality. The control concept is implemented on a PLC and used in industrial spunweb production at Freudenberg Vliesstoffe KG in Kaiserslautern. [less ▲]

Detailed reference viewed: 68 (0 UL)
See detailOptimierung und Charakterisierung einer mittels Laserstrahl gefügten Verbindung zwischen Aluminium und Polyamid 6.6
Lamberti, Christian UL

Doctoral thesis (2018)

The creation of strong joints between dissimilar materials and in particular between polymers and metals is one of the most often discussed topics in the fields of automotive, aerospace and transportation ... [more ▼]

The creation of strong joints between dissimilar materials and in particular between polymers and metals is one of the most often discussed topics in the fields of automotive, aerospace and transportation. Especially the combination of polyamide and aluminum is of highest interest, due to their market share as construction materials. New joining concepts are anticipated to deliver strong, durable and resource efficient structural components that are ideally suited for lightweight designs. However, current research activities have shown that the highly distinct material properties of these materials pose enormous challenges on the creation of hybrid structures. The cause that potentially enables the connection between the aluminum surface and the polymer is still not fully understood. The research objective of the presented work, therefore is, on the one hand, to create an optimal joint between aluminum and polyamide 6.6 using a laser beam to reach high shear strength for an industrial application. On the other hand, the presented work seeks to deliver a substantial contribution to furtherly understand the interaction between the polymer and the metal surface during the thermal joining. A laser-based joining method was developed that enables the researchers to overcome limitations of conventional processes, that is minimizing space requirements, making the application of additional gaskets obsolete, reaching high strength, saving weight and reducing processing time. The effectiveness of different surface pre-treatments has been studied, and the described optimization of this method has lead to an increase of the shear strength of the joints by more than 100 %. Laser ablation and the hydrothermal treatment of the metallic surface, before the joining operation, lead to the highest joint strength. The surface pre-treatment method of laser ablation delivered to transfer the gathered insights and experience from the laboratory to the industrial scale, due to its repeatability and reproducibility. The experiment mentioned above includes the use of production materials, such as aluminum with a higher sheet thickness of up to 1.48 mm and glass fiber reinforced polymer. Shear strength of 40 MPa was reached in quasi-static single lap shear tests. During dynamic testing, samples maintained 63 % of static breaking load after one million cycles. The hydrothermal treatment of the aluminum surface leads to a lower surface roughness of Ra = 1.58 µm in average as opposed to 4.90 µm after laser ablation. Due to the lower roughness values, the first-mentioned method was chosen to study the interaction. An XPS-analysis revealed a strong influence of the surface pre-treatment method on the chemical composition of the metal surface, which becomes noticeable by hydroxylation of the surface layer and is expressed by the oxide ratio (O/Al) and hydroxide ratio (OH/O). A high O/Al ratio of 2.36 and an OH/O ratio of 0.63 after the hydrothermal treatment is showing a strong increase of the amount of hydroxide in direct comparison to values of 35 % and 36 % of OH/O ratio after ethanol and hexane cleaning respectively. The question, as to which extent the presence of such hydroxide structures at the boundary layer of the aluminum influence the interaction between the metal surface and the polymer, was a subject matter of an additional FT-IR analysis. In case of the infrared spectra from thin polymer films on the hydrothermally treated surface, clear indications of interaction are visible. In direct comparison to the infrared spectra from polymer films on either ethanol or hexane cleaned surfaces, this interaction seems to increase nearby of the interface further. The interaction mentioned above appears at the carbonyl band and amine band as a shift of 4 cm-1 and 8 cm-1 and an increase of the full width at half maximum by 35 % respectively 40 %. Additional strong differences are visible at the molecule vibrations below 1,200 cm-1, which are typically assigned to both crystalline phases and amorphous phases of the polyamide. In case of the hydrothermal treatment, collected data indicates a polymorphous state inside the polymer films, which seems to become increasingly disordered close to the interface. On the contrary, spectra from the polymer films on ethanol and hexane pre-treated substrates show only marginal changes. Methods are proposed to build upon the results described in this work and refine distinct signs of the interaction. [less ▲]

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See detailOptimisation and validation of a high throughput screening compatible assay to identify inhibitors of the plasma membrane calcium ATPase pump--a novel therapeutic target for contraception and malaria.
Mohamed, Tamer M. A.; Zakeri, Simon A.; Baudoin, Florence et al

in Journal of Pharmacy and Pharmaceutical Sciences (2013), 16(2), 217-30

PURPOSE: ATPases, which constitute a major category of ion transporters in the human body, have a variety of significant biological and pathological roles. However, the lack of high throughput assays for ... [more ▼]

PURPOSE: ATPases, which constitute a major category of ion transporters in the human body, have a variety of significant biological and pathological roles. However, the lack of high throughput assays for ATPases has significantly limited drug discovery in this area. We have recently found that the genetic deletion of the ATP dependent calcium pump PMCA4 (plasma membrane calcium/calmodulin dependent ATPase, isoform 4) results in infertility in male mice due to a selective defect in sperm motility. In addition, recent discoveries in humans have indicated that a single nucleotide polymorphism (SNP) in the PMCA4 gene determines the susceptibility towards malaria plasmodium infection. Therefore, there is an urgent need to develop specific PMCA4 inhibitors. In the current study, we aim to optimise and validate a high throughput screening compatible assay using recombinantly expressed PMCA4 and the HTRF(R) Transcreener(R) ADP (TR-FRET) assay to screen a drug library. METHODS AND RESULTS: PMCA4 membrane microsomes were prepared from HEK293 cells overexpressing PMCA4. Western blot quantification revealed nearly nine-fold increased expression of PMCA4 compared to LacZ (control virus)-infected cells. Maximal PMCA4 microsomal activity was achieved in the TR-FRET assay with 15ng/mul microsomal concentration, 30-minute pre-incubation with compounds at 37 degrees C, and calcium buffering with 1mM EGTA providing 1muM free-calcium. Finally a dose-response curve for carboxyeosin (a non-specific PMCA inhibitor) under optimised conditions showed significant PMCA4 inhibition. Upon confirmation that the assay was suitable for high-throughput screening, we have screened the ChemBioNet small molecule library (~21,000 compounds) against the PMCA4 assay to identify those that are its apparent inhibitors. This screening yielded 1,494 primary hits. CONCLUSIONS: We have optimised the HTRF(R) Transcreener(R) ADP assay for high-throughput screening to identify PMCA4 inhibitors. The output of the screening campaign has provided preliminary chemical starting points that could be further developed to specific PMCA4 inhibitors for non-hormonal contraception or anti-malaria therapy. [less ▲]

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See detailOptimisation de la prise en charge médicale des patients sortant de prison au Luxembourg
Battista, Jorge; Stein, Romain; Baumann, Michèle UL

Poster (2019)

Le passage en prison peut être un gain de chance pour la santé de la population carcérale qui a généralement un faible accès au système de soins. L’élargissement de prison peut devenir une période de ... [more ▼]

Le passage en prison peut être un gain de chance pour la santé de la population carcérale qui a généralement un faible accès au système de soins. L’élargissement de prison peut devenir une période de vulnérabilité où ce gain potentiellement acquis s’annule si la transition vers la société civile n’est pas anticipée. L’objectif principal était l’identification et l’analyse des facteurs qui favorisent et s’opposent à une pratique de soins primaires chez les patients sortant du milieu carcéral au Luxembourg. L’objectif secondaire était l’élaboration de recommandations à l’égard des principaux résultats en s’appuyant sur une revue de la littérature. Méthodes : Une enquête qualitative à l’aide d’entretiens semi-dirigés a été menée auprès de médecins généralistes et de patients-détenus. Les questions des deux guides d’entretien étaient semblables afin que l’analyse permette une mise en miroir des résultats. Un recueil des caractéristiques sociodémographiques a également été effectué. A l’aide de la transcription des entretiens, une analyse de contenu thématique catégorielle de ces derniers a été réalisée au regard des objectifs. Sur base des verbatim, des items ont été formulés et regroupés en dimensions puis en thèmes. Résultats : Notre analyse a mis en lumière le manque de relais entre la prison et l’extérieur à chaque étape de la prise en charge médico-psycho-sociale du point de vue des soins et des aides proposées en prison jusqu’à l’élargissement. Des recommandations concernant des améliorations possibles ont pu être proposées, comme la création d’un réseau de médecins généralistes prenant le relais ainsi qu’une véritable coopération avec des organisations prenant en charge des toxicomanes. Conclusion : Des reformes concernant les soins en prison devraient être envisagées entre le système de l’élargissement, la création de relais socio-médicaux et des alternatives à l’incarcération, en analogie aux transitions clinics retrouvés aux États-Unis. [less ▲]

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See detailOptimisation of Terahertz Photomixer Layout
Juul, Lars UL

Doctoral thesis (2014)

This thesis examines ways to improve the output power of LT GaAs terahertz photomixer circuits, by focusing on the large impedance mismatch between photoconductor and antenna which gives rise to loss of a ... [more ▼]

This thesis examines ways to improve the output power of LT GaAs terahertz photomixer circuits, by focusing on the large impedance mismatch between photoconductor and antenna which gives rise to loss of a large fraction of power, which could potentially have been absorbed by the antenna. Impedance matching is a known problem in the microwave domain, and in this work such approaches were implemented in the terahertz domain and evaluated using a commercial numerical simulation tool with measured material properties. ?e aim was to provide cost effective design suggestions which are easily integrated into existing single layer technologies. Evaluation of high impedance antennas with integrated DC-blocking showed improvements ranging from 1.5 to 3 times the output power compared to the 3.0 µW reference case at 0.85 THz. A quarterwave transformer with an added shunt capacitance shows a 4 times improvement over the reference case. Adding a multilayer DC-block structure yields a 5 times improvement. Corrugated high impedance wire structures were evaluated for suitability in terms of radiative and transmission properties, in search for improved matching elements. Furthermore, a mechanically tunable resonant photomixer has been proposed, which yields significant improvement in output power over existing tunable broadband photomixers. Finally, a modulation scheme is proposed for binary ASK-modulation in the gigabit per second range of a terahertz photomixer, using an off the shelf 10 Gbps output driver. [less ▲]

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See detailOptimisation of the Co-Digestion of Maize and Grass Silage Influence of the Substrate Mixture on the Biogas Yield
Benito Martin, Patricia Cristina UL; Sibisi-Beierlein, Nonjabulo N.; Greger, Manfred UL

in Bilitewski, B.; Clarke, W. P.; Cossu, R. (Eds.) et al Venice 2012 Fourth International Symposium on Energy from Biomass and Waste Proceedings (2012, November)

In recent years, energy crops have been increasingly introduced as co-substrates in biogas plants due to their high biogas yield potential. The purpose of the current research was to investigate the ... [more ▼]

In recent years, energy crops have been increasingly introduced as co-substrates in biogas plants due to their high biogas yield potential. The purpose of the current research was to investigate the influence of the mixture of maize and grass silages, added as feedstock, on the specific methane production (SMP) and on the process dynamics. To this end, biological methane potential (BMP) tests were carried out in 500ml reactors with grass and maize silage in mono-digestion and 3 different co-digestion mixtures. For selected mixtures, process dynamics were further investigated in batch anaerobic experiments in 1 litre reactors by measuring different control parameters. A positive correlation was observed between the proportion of grass in the mixture and the specific methane yield due to the higher protein content (a yield up to 6% higher in comparison with mono-digestion of maize). Nevertheless, increasing amounts of grass were also related with slower degradation (lower hydrolysis rate constants) and higher instability during the first days of digestion. [less ▲]

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See detailOptimisation of the enhanced distance based broadcasting protocol for MANETs
Ruiz, Patricia UL; Dorronsoro, Bernabé UL; Valentini, Giorgio et al

in Journal of Supercomputing (2012), 62(3), 1213-1240

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See detailOptimisation of the mechanical properties of Miscanthus lightweight concrete (Top 10 Journal)
Pereira Dias, Patrick UL; Waldmann, Danièle UL

in Construction and Building Materials (2020)

In this paper, Miscanthus fibres are used to develop lightweight concrete. The amount of Miscanthus and cement, as well as the water/cement ratio, are varied to analyse the behaviour of the mixture ... [more ▼]

In this paper, Miscanthus fibres are used to develop lightweight concrete. The amount of Miscanthus and cement, as well as the water/cement ratio, are varied to analyse the behaviour of the mixture concerning the physical and mechanical properties. The Miscanthus was pre-treated with a silicate sealant or a cement-based fluid. The current paper analyses the impact of the pre-treatment of the Miscanthus fibres on the compressive strength as well as on the long-term deformations. The specimens with a pre-treatment based on a silicate sealant reached a compressive strength of 19.3 MPa, which is higher than the compressive strength of a conventional LC 16/18, a Young's Modulus above 9.9 GPa and a shrinkage deformation of 2244 μm/m. Nevertheless, considering the density the pre-treatment showed not to be beneficial. [less ▲]

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See detailOptimised Anchor Plates
Dorka, U.; Fromknecht, S.; Maas, S. et al

Presentation (2007)

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See detailOptimised biomolecular extraction for metagenomic analysis of microbial biofilms from high-mountain streams
Busi, Susheel Bhanu UL; Pramateftaki, Paraskevi; Brandani, Jade et al

in PeerJ (2020)

Glacier-fed streams (GFS) are harsh ecosystems dominated by microbial life organized in benthic biofilms, yet the biodiversity and ecosystem functions provided by these communities remain under ... [more ▼]

Glacier-fed streams (GFS) are harsh ecosystems dominated by microbial life organized in benthic biofilms, yet the biodiversity and ecosystem functions provided by these communities remain under-appreciated. To better understand the microbial processes and communities contributing to GFS ecosystems, it is necessary to leverage high throughput sequencing. Low biomass and high inorganic particle load in GFS sediment samples may affect nucleic acid extraction efficiency using extraction methods tailored to other extreme environments such as deep-sea sediments. Here, we benchmarked the utility and efficacy of four extraction protocols, including an up-scaled phenol-chloroform protocol. We found that established protocols for comparable sample types consistently failed to yield sufficient high-quality DNA, delineating the extreme character of GFS. The methods differed in the success of downstream applications such as library preparation and sequencing. An adapted phenol-chloroform-based extraction method resulted in higher yields and better recovered the expected taxonomic profile and abundance of reconstructed genomes when compared to commercially-available methods. Affordable and straight-forward, this method consistently recapitulated the abundance and genomes of a mock community, including eukaryotes. Moreover, by increasing the amount of input sediment, the protocol is readily adjustable to the microbial load of the processed samples without compromising protocol efficiency. Our study provides a first systematic and extensive analysis of the different options for extraction of nucleic acids from glacier-fed streams for high-throughput sequencing applications, which may be applied to other extreme environments. [less ▲]

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See detailOptimised recovery with a coordinated checkpoint/rollback protocol for domain decomposition applications
Besseron, Xavier UL; Gautier, Thierry

in Modelling, Computation and Optimization in Information Systems and Management Sciences. MCO 2008 (2008, September)

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See detailOptimising Packet Forwarding in Multi-Tenant Networks using Rule Compilation
Hommes, Stefan UL; Valtchev, Petko; Blaiech, Khalil et al

in Optimising Packet Forwarding in Multi-Tenant Networks using Rule Compilation (2017, November)

Packet forwarding in Software-Defined Networks (SDN) relies on a centralised network controller which enforces network policies expressed as forwarding rules. Rules are deployed as sets of entries into ... [more ▼]

Packet forwarding in Software-Defined Networks (SDN) relies on a centralised network controller which enforces network policies expressed as forwarding rules. Rules are deployed as sets of entries into network device tables. With heterogeneous devices, deployment is strongly bounded by the respective table constraints (size, lookup time, etc.) and forwarding pipelines. Hence, minimising the overall number of entries is paramount in reducing resource consumption and speeding up the search. Moreover, since multiple control plane applications can deploy own rules, conflicts may occur. To avoid those and ensure overall correctness, a rule validation mechanism is required. Here, we present a compilation mechanism for rules of diverging origins that minimises the number of entries. Since it exploits the semantics of rules and entries, our compiler fits a heterogeneous landscape of network devices. We evaluated compiler implementations on both software and hardware switches using a realistic testbed. Experimental results show a reduction in both produced table entries and forwarding delay. [less ▲]

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See detailOptimising patients’ medical care after prison in Luxembourg
Batista, Jorge; Stein, Romain; Baumann, Michèle UL

in General Practice : The human side of medicine (2019)

Introduction : Passing through prison can be a health gain for the incarcerated population and release from prison can become a period of vulnerability where this potentially acquired gain is lost if the ... [more ▼]

Introduction : Passing through prison can be a health gain for the incarcerated population and release from prison can become a period of vulnerability where this potentially acquired gain is lost if the transition back to civil society in not anticipated. The main objective was the identification and analysis of the factors favor and oppose primary care practice for patients leaving prison in Luxembourg. The secondary objective was to develop recommendations based on the key findings through a literature’s review. Methods : A qualitative study using semi-structured interviews was conducted with general practitioners and patient-inmates. The questions from the two interview guides were similar so that the analysis allowed the results to be mirrored. Using the interviews’ transcripts, a categorical thematic content analysis of those was conducted based on the objectives. On the basis of verbatim, items were formulated and grouped into dimensions and then themes. Results : Our analysis has highlighted the lack of links between the prison and the outside world at each stage of medical and psychosocial care from the point of view of care and support proposed in prison until prison release. Recommendations for doable improvements have been proposed, such as the creation of a general practitioners’ network continuing the medical care as well as genuine cooperation with organisations dealing with drug addicts. Conclusion : Reforms concerning prison care should be considered between the system of prison release, the creation of socio-medical relays and alternatives to incarceration, in analogy to the transitions clinics found in the United States [less ▲]

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See detailOptimising pheromone communication in a UAV swarm
Stolfi, Daniel H.; Brust, Matthias R. UL; Danoy, Grégoire UL et al

in GECCO '21: Genetic and Evolutionary Computation Conference, Companion Volume, Lille, France, July 10-14, 2021 (2021)

Detailed reference viewed: 42 (2 UL)