| 1. |
- Johansson, Ted, et al.
(författare)
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Influence of SOI-generated stress on BiCMOS performance
- 2006
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Ingår i: Solid-State Electronics. - : Elsevier BV. - 0038-1101 .- 1879-2405. ; 50:6, s. 935-942
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Tidskriftsartikel (refereegranskat)abstract
- Two BiCMOS processes were adapted for SOI and the performance of the bipolar devices was studied. Differences in electrical parameters were observed, in particular the current gain, which processing or doping profiles could not explain, but correlated with observed stress in transistors. Simulation of the process flow with stress included revealed that stress was generated to a higher degree in the SOI wafers in the presence of deep trench isolation (DTI). Theoretical estimations and electrical simulations with and without stress yielded results consistent with observed data. Thus, we conclude that the observed differences are caused by process-induced in-plane biaxial stress.
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| 2. |
- Wannberg, Gudmund, et al.
(författare)
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EISCAT_3D - a next-generation European radar system for upper atmosphere and geospace research
- 2010
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Ingår i: Radio Science Bulletin. - 1024-4530. ; :333, s. 75-88
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Tidskriftsartikel (refereegranskat)abstract
- The EISCAT Scientifi c Association, together with a number of collaborating institutions, has recently completed a feasibility and design study for an enhanced performance research radar facility to replace the existing EISCAT UHF and VHF systems. This study was supported by EU Sixth-Framework funding. The new radar retains the powerful multi-static geometry of the EISCAT UHF, but will employ phased arrays, direct-sampling receivers, and digital beamforming and beam steering. Design goals include, inter alia, a tenfold improvement in temporal and spatial resolution, an extension of the instantaneous measurement of full-vector ionospheric drift velocities from a single point to the entire altitude range of the radar, and an imaging capability to resolve small-scale structures. Prototype receivers and beamformers are currently being tested on a 48-element, 224 MHz array (the "Demonstrator") erected at the Kiruna EISCAT site, using the EISCAT VHF transmitter as an illuminator.
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| 3. |
- Alander, B., et al.
(författare)
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A facile way of making inexpensive rigid and soft protein biofoams with rapid liquid absorption
- 2018
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Ingår i: Industrial crops and products (Print). - : Elsevier. - 0926-6690 .- 1872-633X. ; 119, s. 41-48
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Tidskriftsartikel (refereegranskat)abstract
- A novel and facile method to produce inexpensive protein biofoams suitable for sponge applications is presented. The protein used in the study was wheat gluten (WG), readily available as a by/co-product, but the method is expected to work for other cross-linkable proteins. The foams were obtained by high-speed stirring of pristine WG powder in water at room temperature followed by drying. Glutaraldehyde was used to crosslink the foam material in order to stabilize the dispersion, reduce its tackiness and improve the strength of the final foam. The foams were of medium to high density and absorbed readily both hydrophobic and hydrophilic liquids. The foam structure, consisting primarily of an open pore/channel system, led to a remarkably fast capillary-driven (pore-filling only) uptake of a hydrophobic liquid (limonene). Essentially all uptake occurred within the first second (to ca. 90% of the dry weight). In a polar liquid (water), the rapid pore-filling occurred in parallel with a more time-dependent swelling of the foam matrix material. Further improvement in the foam strength was achieved by making a denser foam or adding TEMPO-oxidized cellulose nanofibres. Soft foams were obtained by adding glycerol.
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| 4. |
- Haralson, Erik, et al.
(författare)
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Influence of self heating in a BiCMOS on SOI technology
- 2004
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Ingår i: ESSCIRC 2004. - NEW YORK : IEEE. - 0780384784 ; , s. 337-340
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Konferensbidrag (refereegranskat)abstract
- Self heating in a 0.25mum BiCMOS technology with different isolation structures is characterized. Thermal resistance values for single- and multiple-emitter devices are extracted and reported. The dependence of the thermal resistance on the emitter aspect ratio is critical to take into consideration when determining the isolation scheme for devices. 2-D electro-thermal simulations are performed and compared to experimental results. The impact of metallization on the self-heating in the device is examined through simulations.
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| 5. |
- Rombouts, I., et al.
(författare)
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Crosslinks in wheat gluten films with hexagonal close-packed protein structures
- 2013
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Ingår i: Industrial crops and products (Print). - : Elsevier BV. - 0926-6690 .- 1872-633X. ; 51, s. 229-235
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Tidskriftsartikel (refereegranskat)abstract
- Wheat gluten/glycerol (WGG) films were extruded with aqueous ammonia/salicylic acid or urea to investigate the reactions contributing to their hexagonal close-packed protein structures and material properties. The addition of aqueous ammonia and salicylic acid increased the pH, which, in turn, increased the level of intermolecular disulfide and lanthionine cross-links in the WGG films. Increased protein cross-linking reactions resulted in higher material strength and tensile modulus. These cross-linking reactions and the resulting material properties were similar for WGG films with 7.5% and 10% aqueous ammonia. Added urea into WGG film partially degraded into cyanate and ammonium. Cyanate subsequently reacted with lysine and cysteine to ε-carbamyllysine and S-carbamylcysteine, respectively. Even though these reactions resulted in a more alkaline reaction environment, hereby favoring disulfide bond formation and decreasing protein extractability, they also prevented the involvement of cysteine and lysine in protein cross-linking. The alkylation of these reactive amino acids, together with the plasticizing effect of urea, led to lower material strength and elastic modulus with increasing levels of urea.
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| 6. |
- Zou, Zhenhua, 1984-
(författare)
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Real-time communication in wireless lossy networks
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The last decades’ tremendous advances in wireless communications havebeen driven mainly by personal communications. Radio resource allocationmechanisms for optimizing key metrics, such as average throughput and delay,are by now rather well-developed. However, with the increased interest inwireless machine-to-machine communication, new challenges emerge, such asmulti-hop connectivity, lossy and bursty links, battery-powered nodes, andchanging/unknown link parameters, among others. With these challenges inmind, this thesis studies real-time communication in wireless lossy networks,and how the resulting networking primitive can be used to design networkedcontrol systems with optimal closed-loop performance.First, we study optimal forwarding of deadline-constrained traffic overmulti-hop networks with losses on links described by finite-state Markovchains. We consider two problems: maximizing the probability that packetsare delivered within specified deadlines; and minimizing the expected energycost with a guaranteed probability of on-time delivery. Both problems fallinto the category of Markov Decision Processes and can be studied in a generaldynamic programming framework. Particular instances with Bernoulliand Gilbert-Elliot loss models, which admit insight and efficient computations,are discussed. Moreover, a number of extensions and variations ofthe deadline-constrained forwarding problem are investigated. These extensionsinclude systems with unknown channel states and unknown link lossmodels, scenarios with multiple concurrent flows, and solutions adapted toopportunistic routing and the recent WirelessHART standard.Second, we show how the solution for the deadline-constrained forwardingproblem can be used in the optimal co-design of networked control systems.Specifically, we consider the joint design of packet forwarding policies andcontrollers for wireless control loops where sensor data are sent to the controllerover an unreliable and energy-constrained multi-hop wireless network.For fixed sampling rate of the sensor, the co-design problem separates into twowell-defined and independent subproblems: transmission scheduling for maximizingthe deadline-constrained reliability and optimal control under packetloss. We develop optimal and implementable solutions for these subproblemsand show that the optimally co-designed system can be efficiently found.Finally, we study online shortest-path routing problems in which link delaysare time-varying and modeled by random processes with initially unknownparameters. The optimal path can only be estimated by routing packetsthrough the network and observing the realized delays. The aim is to finda routing policy that minimizes the regret (the cumulative delay difference)between the path chosen by the policy and the unknown optimal path. Weformulate the problem as a combinatorial bandit optimization problem andconsider several scenarios. For each scenario, we derive the tight asymptoticlower bound on the regret that has to be satisfied by any online routing policy.These bounds help us to understand the performance improvements wecan expect when (i) taking routing decisions at each hop rather than at thesource only, and (ii) observing per-link costs rather than aggregate path costs.Efficient algorithms are proposed and evaluated against the state-of-the-art.
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| 7. |
- Besselink, B., et al.
(författare)
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D-stability and delay-independent stability of monotone nonlinear systems with max-separable Lyapunov functions
- 2016
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Ingår i: 2016 IEEE 55th Conference on Decision and Control, CDC 2016. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781509018376 ; , s. 3172-3177
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Konferensbidrag (refereegranskat)abstract
- Stability properties of monotone nonlinear systems with max-separable Lyapunov functions are considered in this paper, motivated by the following observations. First, recent results have shown that such Lyapunov functions are guaranteed to exist for asymptotically stable monotone systems on compact sets. Second, it is well-known that, for monotone linear systems, asymptotic stability implies the stronger properties of D-stability and robustness with respect to time-delays. This paper shows that similar properties hold for monotone nonlinear systems that admit max-separable Lyapunov functions. In particular, a notion of D-stability for monotone nonlinear systems and delay-independent stability will be discussed. The theoretical results are illustrated by means of examples.
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| 8. |
- Blanco, A., et al.
(författare)
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Performance of timing resistive plate chambers with relativistic neutrons from 300 to 1500 MeV
- 2015
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Ingår i: Journal of Instrumentation. - : IOP Publishing. - 1748-0221. ; 10:2
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Tidskriftsartikel (refereegranskat)abstract
- A prototype composed of four resistive plate chamber layers has been exposed to quasi-monoenergetic neutrons produced from a deuteron beam of varying energy (300 to 1500 AMeV) in experiment S406 at GSI, Darmstad, Germany. Each layer, with an active area of about 2000 × 500 mm2, is made of modules containing the active gaps, all in multigap construction. Each gap is defined by 0.3 mm nylon mono-filaments positioned between 2.85 mm thick float glass electrodes. The modules are operated in avalanche mode with a non-flammable gas mixture composed of 90% C2H2F4 and 10% SF6. The signals are readout by a pick-up electrode formed by 15 copper strips (per layer), spaced at a pitch of 30 mm, connected at both sides to timing front end electronics. Measurements of the time of flight jitter of neutrons, in the mentioned energy range, point to a contribution of the resistive plate chamber in the order of 150 ps, independent of the neutron energy.
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| 9. |
- Malm, B. Gunnar, et al.
(författare)
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Self-heating effects in a BiCMOS on SOI technology for RFIC applications
- 2005
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Ingår i: IEEE Transactions on Electron Devices. - : IEEE Press. - 0018-9383 .- 1557-9646. ; 52:7, s. 1423-1428
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Tidskriftsartikel (refereegranskat)abstract
- Self-heating in a 0.25 mu m BiCMOS technology with different isolation structures, including shallow and deep trenches on bulk and silicon-on-insulator (SOI) substrates, is characterized experimentally. Thermal resistance values for single- and multifinger emitter devices are extracted and compared to results obtained from two-dimensional, fully coupled electrothermal simulations. The difference in thermal resistance between the investigated isolation structures becomes more important for transistors with a small aspect ratio, i.e., short emitter length. The influence of thermal boundary conditions, including the substrate thermal resistance, the thermal resistance of the first metallization/via layer, and the simulation structure width is investigated. In, the device with full dielectric isolation-deep polysilicon-filled trenches on an SOI substrate-accurate modeling of the heat flow in the metallization is found to be crucial. Furthermore, the simulated structure must be made wide enough to account for the large heat flow in the lateral direction.
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