In wireless smart metering optimization for energy efficiency is indispensable, because in case of systems without external power supply, battery life is a key factor regarding the usability of the whole system. Senso...
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In wireless smart metering optimization for energy efficiency is indispensable, because in case of systems without external power supply, battery life is a key factor regarding the usability of the whole system. Sensor networks are less sensitive for delay, this is why aggregation of packets is possible. The aim of this paper is to determine analytically the amount of meter records to aggregate in one packet, regarding the SNR which characterizes the quality of the channel, so that the energy usage is optimal. The introduced formulas, help determining scheduling parameters in wireless smart metering systems. The calculations are presented on a real world scenario and system using GFSK modulation.
This paper presents a novel approach for off-line signature verification. First the different aspects and problems of signature verification are discussed in conjunction with off-line analysis methods. It is shown, th...
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This paper presents a novel approach for off-line signature verification. First the different aspects and problems of signature verification are discussed in conjunction with off-line analysis methods. It is shown, that on-line analysis methods perform usually better than off-line methods because they can make use of the temporal information (and thereby get a better perception of the semantics of the signature). An assumption is made, that off-line verification methods have difficulties improving their results because of the high level of abstraction they use, which is a direct consequence of the missing semantics. Afterwards a solution is presented with the ability to preserve some semantic information, and thereby deliver a better ability to analyze the results and optimize the system.
We examined the quality and the reliability of lead-free solder joints which were made with a selective laser soldering process. The three types of applied substrate materials - polyimide (PI), a kind of polyester (PE...
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We examined the quality and the reliability of lead-free solder joints which were made with a selective laser soldering process. The three types of applied substrate materials - polyimide (PI), a kind of polyester (PET) and polyethylene-naphtalate (PEN) - withstood the local heat dose even if the allowed temperature limits of them were lower than the melting points of the applied solders. We used substrates with different adhesives and cover layers. The two types of solder pastes were SnBi and SnAgCu (SAC) alloys. Altogether 16 solder-substrate-adhesive combinations were tested and compared to similar reflow soldered combinations when the implementation of the technology was possible. The testboards were submitted to HAST (highly accelerated stress test) and the degradation was monitored. Optical inspection and shear force measurements were used for comparative analyses. As a result, the combinations were put in order on the basis of these data. With these achievements; the processing, materials, product performance and reliability could be improved.
The size decreison of passive components nowadays reaches 01005 dimension. For larger components also, but for these tiny components the accuracy of the component placement machines is a very important variable in res...
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The size decreison of passive components nowadays reaches 01005 dimension. For larger components also, but for these tiny components the accuracy of the component placement machines is a very important variable in respect of the placement quality. There are other variables that affect the placement quality (the quality of the solder paste, or the adhesive etc.), but I only studied the methods, that could improve the accuracy of the placement machines. It was a very important aspect that I use the method that is suggested in the standard: IPC-9850, but not to use expensive, special optical CMM (Calibrated Measuring Machine), and not to use expensive tester components (QFP, R, C, etc.) either.
A major problem with tin electroplating is the formation of tin whiskers. These are spontaneous protrusions of few microns in diameter and up to hundreds of microns or even millimeters in length. There are several mit...
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A major problem with tin electroplating is the formation of tin whiskers. These are spontaneous protrusions of few microns in diameter and up to hundreds of microns or even millimeters in length. There are several mitigation strategies and using a nickel or silver underplate is proven to be excellent in preventing the forming of Cu 6 Sn 5 intermetallics. Still there are not many scientific researches about the effects of this mitigation strategy. Therefore we have tested leadframe samples in different temperature and humidity conditions (105degC/100% relative humidity (RH), 50degC/25% RH) for over 3400 hours. Both leadframes were on bronze substrates and had 1-2 mum underplates (silver or nickel) with 5-7 mum tin on the top. Our results have shown hillock and whisker growth differences on the samples depending on the nature of the different environmental circumstances, which is originated to the different stress-causing mechanisms, and also growth differences have been found on the different underplate materials.
Skype uses strong encryption to secure communications inside the whole Skype network. Clients choose communication ports randomly. Therefore traditional port based or payload based identification of Skype traffic is n...
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Skype uses strong encryption to secure communications inside the whole Skype network. Clients choose communication ports randomly. Therefore traditional port based or payload based identification of Skype traffic is not feasible. In this paper we introduce a novel flow dynamics based identification method to discover Skype host and voice calls as well. Our method uses only packet headers and the extracted flow level information. The whole identification process is scripted in Transact-SQL, thus it can be executed automatically. We also present the validation of the algorithm together with some analysis of the identification results.
The design of a wide tuning range voltage controlled oscillator (VCO) for integrated phase locked loop (PLL) is presented. The circuit was implemented on a 0.35um bicmos technology. The VCO had 36% tuning range togeth...
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The design of a wide tuning range voltage controlled oscillator (VCO) for integrated phase locked loop (PLL) is presented. The circuit was implemented on a 0.35um bicmos technology. The VCO had 36% tuning range together with good figure of merit. The paper shows the design methodology used to obtain small tuning gain variation in the whole frequency, temperature and process variation range. Some design details are shown together with measurement results.
This paper presents an online time scaling concept for robotic manipulators. The task is to ensure the fastest possible motion along a trajectory with a given geometry in the robot workspace. The other requirement is ...
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This paper presents an online time scaling concept for robotic manipulators. The task is to ensure the fastest possible motion along a trajectory with a given geometry in the robot workspace. The other requirement is tracking accuracy. Robots should move not only with high speed but with high precision as well. The speed of the motion cannot be arbitrary fast. It is delimited by the saturation of the actuators and by some other (e.g. security) constraints. Offline time scaling solutions change the speed of the motion without changing its geometry, thus these constraints are not violated. If the exact torque bounds are not known in advance, another method should be used. This work gives an online time scaling algorithm which is based on the tracking error. Simulations demonstrate the usefulness of the algorithm proposed
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