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排序方式: 共有463条查询结果,搜索用时 15 毫秒
381.
Jiri Hosek Pavel Masek Dominik Kovac Michal Ries Franz Kröpfl 《e & i Elektrotechnik und Informationstechnik》2014,131(4-5):123-128
There are many candidates for a communication infrastructure between the smart home gateway and service providers, distribution centers or end-users accessing smart home applications remotely. Optimally the access technology should be already deployed in order to minimize initial investments and in parallel must provide sufficient reliability and security even for critical applications. Therefore, we focused at already deployed platforms which have a strong potential to become the key communication technologies for smart home domain. Furthermore, we investigated the applicability of residential gateway access technology for emerging home automation services. Finally, we developed and demonstrate a middleware solution enabling the “state of technology” IP-based home gateway to serve as a universal multi-purpose enabler for connected home automation systems like alarm systems, smart metering and grid, photo-voltaic energy production systems, etc. 相似文献
382.
A new technique for measurement of magnetic properties of materials is demonstrated. It can be used for the measurement of thin magnetic films during their chemical modification. The resonance frequency of a quartz crystal microbalance (QCM) with conducting polymer (polyaniline) suspension in poly(ethylene glycol) was observed to increase with increasing the externally applied uniform dc magnetic field. Slowly sweeping the magnetic field between 0 and 3.1 T results in a frequency-field response curve. Chemical doping was done by exposing the polyaniline-emeraldine base film to HCl vapor. The change in population of free spins is reflected in increased frequency-field curve magnitude after HCl doping. Two working hypotheses explaining this observation are offered to explain how frequency of QCM with deposited magnetic film shifts with increasing intensity of the magnetic field. 相似文献
383.
Steven C. Cermak Jakob W. Bredsguard Billee L. John Kristy Kirk Travis Thompson Katelyn N. Isbell Kati A. Feken Terry A. Isbell Rex Murray 《Journal of the American Oil Chemists' Society》2013,90(12):1895-1902
Acetic‐ and butyric‐capped oleic estolide 2‐ethylhexyl (2‐EH) esters were synthesized in a perchloric acid catalyzed (0.05 equiv) one‐pot process from industrial 90 % oleic acid and either acetic or butyric fatty acids at two different ratios. This was directly followed by the esterification process incorporated into an in‐situ second step to provide a low viscosity estolide ester functional fluid. The monoestolide and polyestolides were separated via vacuum distillation (6–13 Pa) at 240–250 °C. The physical properties of these materials were followed throughout the synthetic process and are reported. The final low viscosity acetic‐ and butyric‐capped monoestolide 2‐EH esters had viscosities of 19.9 and 24.2 cSt at 40 °C and 4.8 and 5.5 cSt at 100 °C with viscosity indexes (VI) of 161 and 163, respectively. Both monoestolide esters displayed excellent pour points (PPs). The PPs of the two were as follows: acetic‐capped estolide 2‐EH ester PP = ?45 °C and butyric‐capped estolide 2‐EH ester PP = ?27 °C. The biodegradable short‐capped oleic estolide 2‐EH esters had excellent low temperature properties and should perform well in low viscosity applications. 相似文献
384.
This paper describes the design and experimental verification of a current-mode multiphase sinusoidal oscillator (MSO) employing current differencing units. The oscillator, composed of n 1st-order all-pass sections, generates harmonic current signals with 2n equidistant phase shifts, where n ≥ 2. Compared with conventional MSOs, this circuit is characterized by an extremely simple circuitry and a minimum number of passive and active components. The oscillation condition and the frequency of oscillation are orthogonally controlled. The proposed circuit is suitable for IC fabrication. Experimental verification on an erlier manufactured chip together with a detailed analysis of real influences are included in the paper. 相似文献
385.
Modern communication networks cannot get along without quality of service (QoS) assurance. QoS-support mechanisms offer preferential treatment for specific traffic classes that is required especially by real-time network applications. Unfortunately current QoS technologies have certain disadvantages and limitations and therefore they are not always able to guarantee the required QoS level. This paper introduces a quality of service support system that improves the most often used quality of service support technology called Differentiated Services (DiffServ). The system proposed utilizes the Simple Network Management Protocol (SNMP) for the acquisition of configuration information from the edge router of the DiffServ domain. This information is subsequently used to control the allocation of network resources within the QoS assurance process. In order to evaluate this system we used the OPNET Modeler simulation environment where we built a simulation scenario able to interact with real network components. For this purpose we implemented the SNMP protocol into the OPNET Modeler and used it for acquisition of management information, stored in the Management Information Base (MIB) of the network node. The paper describes in details the improved QoS-support mechanism and the simulation model able to cosimulate the behavior of both real and virtual network elements. 相似文献
386.
In order to mimic the operation of the air-cathode in a direct borohydride alkaline fuel cell, we studied the oxygen reduction reaction (ORR) in sodium hydroxide solution containing traces of borohydride. The activity of several ORR electrocatalysts, namely carbon-supported platinum, gold, silver and manganese oxide, has been investigated using slow-scan linear voltammetry. Whereas platinum is one of the best electrocatalyst in pure sodium hydroxide, none of the classical electrocatalysts: gold, silver and platinum, exhibit sufficient selectivity towards the ORR. When BH4− is present in solution, the potential taken by electrodes using such materials is a mixed potential, following the competition between the ORR and the NaBH4 hydrolysis and/or oxidation. Conversely, manganese oxide-based electrocatalysts exhibit very interesting behaviour towards the ORR in alkaline medium; while their intrinsic ORR activity in pure sodium hydroxide is quite as good as that for platinum, they still display a remarkable selectivity for this reaction when the electrolyte contains traces of sodium borohydride.As a result, carbon-supported manganese oxide-based nanoparticles seem very interesting materials to be used in direct borohydride fuel cell. 相似文献
387.
The structure of selected special (Σ=5) symmetrical tilt grain boundaries in Ni3Al with tilt axis [1 0 0] was simulated by the Monte Carlo method. Vacancies were generated both in Al and Ni sites in their relaxed structure and the vacancy formation and migration energy was estimated. 相似文献
388.
389.
Zdenek Kaspar 《电子产品世界》2006,(12):65,62
在汽车工业中,采用更先进的控制系统则意味着要求汽车内的通信要面对更多的挑战.这些新的要求通过网络就可解决.由于汽车内的环境十分特殊,在汽车工业中有三种主要的通信标准. FlexRay速度最快(每通道可达10Mbps).它含有两个通道,都是时间触发、具有鲁棒性且有容错能力,可用作骨干网.典型的目标应用是X-by-wire概念. 相似文献
390.
Ivo Schindler Rudolf Kawalla Jiri Plura Tomas Kubina Stanislav Rusz Eugeniusz Hadasik Vladislav Jurko 《国际钢铁研究》2008,79(10):758-764
The aim of this work was to describe the deformation resistance of austenitized Ti‐IF steel in the temperature range of 650 to 1100°C by a complex equation. The mean flow stress was determined by an original procedure, based on laboratory rolling of flat samples. Deformation resistance was described by a single formula, using a cumulative function in which particular terms are multiplied by a coefficient of 1 or 0, in dependence on a specific temperature. Calculation of specific coefficients had to be proposed in such a way that they could react to exceeding temperature boundaries between individual phase regions. The developed model can be used for off‐line predictions of power/force parameters in the forming of Ti‐IF steel, in a wide range of conditions of hot and warm deformation. 相似文献