587 research outputs found
SCI citation analysis and impact factor prediction of JZUS-B in 2008
Full text linkWe analysis the SCI citation of Journal of Zhejiang University-SCIENCE B, predict its 2008 Impact Factor in the range of 0.737~0.915, and list the top-10 SCI cited articles
Corydalis austroshaanxiensis sp. nov. (Papaveraceae), a neglected species from Shaanxi, China, and a revised circumscription for C. pseudoincisa C.Y. Wu, Z.Y. Su & Lidén
No full textCorydalis austroshaanxiensis, a new species of Corydalis sect. Incisae Fedde (Papaveraceae) from Shaanxi, China, is described. It is most similar to C. pseudoincisa C.Y. Wu, Z.Y. Su & Lidén, but differs in the outer petals retuse to emarginate, with dorsal crest (vs acuminate, rounded to shortly mucronate, without crest), lowermost pedicels that are conspicuously elongating and basally recurved in fruit (vs slightly elongating, straight, erect-spreading), sepals that are 3–4 × ca. 3 mm (vs 1.5–2 × ca. 1.5 mm), lower petals that usually have a linear reddish tint at base (vs without reddish tint), capsules that are narrowly to broadly elliptic to obovoid (vs linear to narrowly oblong), and by the racemes corymbose, forming a very dense cluster of upper fruits (vs racemes not corymbose-like, flower dense in anthesis, lax in fruit). The original materials, which were referred to C. pseudoincisa were mosaic, and the original descriptions and illustrations annotated as C. pseudoincisa only fit in part C. pseudoincisa. A revised circumscription for C. pseudoincisa was given in this study. We suggest the need for caution when identifying additional specimens as paratypes that differ from holotype in distinct characters.Funding provided by: National Natural Science Foundation of ChinaCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100001809Award Number: 31170310After extensive field collections and the study of herbarium specimens, we confirm that these unusual plants represent a hitherto undescribed species
Een draadloze sensor voor het monitoren van bederfelijke producten
No full textOm een pH-sensor[1], ontwikkeld binnen het PASTEUR-project [2], aan te kunnen sturen en uit te kunnen lezen is een ontwerp voor een sensorsysteem gemaakt dat de pH en temperatuur in vlees kan monitoren. Belangrijke eigenschappen hiervan zijn het lage energieverbruik, de draadloze digitale communicatie en het kleine formaat. Het systeem meet gedurende 48 uur elke tien minuten de pH en slaat deze op. Andere intervallen zijn ook mogelijk, maar dat verandert wel de tijd waarin het systeem blijft werken. De gebruiker kan al deze data ophalen via een reader en ook een instantane meting aanvragen. Het sensorsysteem is opgedeeld in twee onderdelen: de draadloze communicatie en de sensor node. In deze thesis wordt het ontwerp van de sensor node besproken. Deze stuurt de sensor daadwerkelijk aan, slaat de rauwe data van de pH en temperatuur op en geeft dit door aan de draadloze communicatie zodat deze de data kan versturen naar een computer, die de data verder verwerkt. De sensor node bestaat uit een microcontroller en een extern geheugen om alle data in op te slaan. Daarnaast bestaat het uit hardware om de communicatie met de RFID-tag en de sensorstick mogelijk te maken. Het systeem bevindt zich het grootste gedeelte van de tijd in sleep mode om energie te besparen. De microcontroller die hiervoor gebruikt is, is de C8051F986 van Silicon Labs, welke de laagste sleep mode current heeft op de huidige markt. Het geheugen is een 24AA64-I/OT, een EEPROM chip van 64kbit met I2C communicatie. De draadloze communicatie zal door middel van RFIDtechniek tot stand komen. De groep die dat ontworpen heeft, gebruikt de TMS37157, een passieve RFID interface met SPI aansturing. Een protocol is ontwikkeld, genaamd het Data Link Protocol, om foutloze dataoverdracht te garanderen. De sensor node wordt gevoed door een 3V lithium knoopcel. De microcontroller en het geheugen wordt direct gevoed door de batterijspanning, de pH-sensor door een 1,8V regulator, en het RFID subsysteem wordt enkel gevoed door de RF energie van de reader. De software is geschreven in C en werkt zonder operating system, omdat er slechts één proces tegelijkertijd zal worden uitgevoerd en een OS dus niet noodzakelijk is. De software is opgebouwd uit een toplaag, een middenlaag en drivers. De toplaag bestaat uit de mainfunctie die controle heeft over de functie die met de TMS37157-chip communiceert, de functie die het geheugen beheert, de slaapfunctie en de functie die de pH-sensor aanstuurt en uitleest. Vanuit de TMS37157-chip kunnen acht verschillende commando’s komen die door de sensor node moeten worden opgevolgd. Op basis hiervan roept de mainfunctie de juiste functies aan. Ondanks de CRC-check van de TMS37157-chip moet de foutdetectie van de draadloze communicatie extra verzekerd worden, omdat de CRC geen rekening kan houden met geheel niet ontvangen van verzendingen. Daarvoor is er een data link protocol ontwikkeld. In het geheugen worden de kalibratiemetingen, de geplande metingen en de instantane metingen apart opgeslagen. Hierbij is ervoor gezorgd dat genoeg ruimte is om acht kalibratiemetingen op te slaan. Bij deze kalibratiemetingen worden de time stamp en de pH-waarde, door de gebruiker meegegeven, opgeslagen. Zonder getriggerde metingen is er daarnaast nog ruimte om 2698 geplande metingen op te slaan, wat meer dan voldoende is voor wat nodig is om 48 uur lang elke tien minuten een meting te doen. Dit aantal is wat minder met getriggerde metingen erbij, omdat deze meer ruimte innemen. Het ontwerp is nog niet getest, dus er zijn nog geen algemene resultaten te zien, maar met behulp van een logic analyser is wel aangetoond dat het beheren van de EEPROM en de communicatie met de TMS-chip via SPI werkt.Microelectronics & Computer EngineeringElectrical Engineering, Mathematics and Computer Scienc
Wireless Indoor Climate Sensor: Implementing the Control Unit at Ultra Low Power
No full textWith the completion of the MIST1431 multi sensor IC a demonstrator developed by the Electronic Instrumentation Laboratory of Delft University of Technology and NXP, a demonstrator that shows the capabilities of the MIST chip was needed. This thesis describes the implementation of the control unit, which has to control the MIST chip and wireless communication module residing in the demonstrator. Temperature and relative humidity had to be transmitted wirelessly at low power consumption. A method of analysis and assessment of the different methods and hardware was developed. Then a suitable controller was chosen: the LPC1114. After choosing the controller, a study about the functionalities of the controller was done. Software was designed and written. Finally measurements were taken proving the functionalities of the demonstrator. Testing showed that the demonstrator is capable of sending its measurements once per second to a computer while using a mean of 50.807?A. The result is that the demonstrator meets its requirements.ElektrotechniekElectronic Instumentation LaboratoryElectrical Engineering, Mathematics and Computer Scienc
Black Soybean Promotes the Formation of Active Components with Antihepatoma Activity in the Fermentation Product of Agaricus blazei
No full textNumerical thermo-mechanical stress analysis for HVDC cables
Full text linkCalculating the current rating of paper insulated HVDC cables under low ambient temperatures can require additional mechanical considerations. Under rapid cable heating or cooling processes, an extremely high mechanical stress or a rapid pressure drop can develop due to the strong impregnant thermal expansion or contraction respectively. This may cause plastic deformation of the sheath or the creation of voids. This paper demonstrates the importance of this thermo-mechanical constraint through the application of finite element modelling techniques which permit a coupling of the thermal and mechanical properties within the cable. The results show that the FEA technique can be fully applied to analyze the internal thermo-mechanical stress distribution of the cable and calculate the resulting mechanical stress-limited rating, which provides an alternative to an analytical method previously developed by the same author
Een draadloze sensor voor het monitoren van bederfelijke producten: Draadloze communicatie ontwerp
No full textIn deze bachelorthesis wordt een ontwerp gepresenteerd van draadloze communicatie voor een draadloos sensorsysteem voor het automatisch meten van pH en temperatuur. Het is gelukt een volledig passieve RFID tag te selecteren en deze te integreren in een PCB ontwerp met de andere onderdelen van het sensorsysteem. Op basis van een proof of concept is aangetoond dat communicatie vanaf een PC via een reader en RFID tag met een microcontroller mogelijk is voor het aansturen van het sensorsysteem en het uitlezen van opgeslagen data op 2 cm afstand. De communicatie tussen RFID tag en microcontroller vindt hierbij plaats via een SPI interface en de functionaliteiten voor het aansturen van de reader zijn geïmplementeerd in MATLAB.EE3842 Bachelor afstudeerproject (2012-2013 Q4)Electronic Instrumentation LaboratoryElectrical Engineering, Mathematics and Computer Scienc
Wireless Indoor Climate Sensor: Wireless Communication at Ultra Low Power
No full textThe required product is a wireless indoor climate sensor. It is an autonomous sensor that transmits several parameters concerning its environment wirelessly. The product will be used to demonstrate a number of energy efficient sensors. The electronic instrumentation department at Delft University of Technology developed these sensors in association with NXP. Since the desire to communicate information wirelessly in an energy efficient way existed, several options could be explored. First a wireless protocol had to be chosen. Thereafter, a hardware solution had to be found in order to implement the chosen protocol. Lastly, the information had to be displayed on a computer screen. This thesis investigates six wireless protocols that can transmit information. The investigated protocols are Bluetooth, ZigBee, Rubee, UWB, Z-Wave and the well known Wi-Fi. In order to choose the right option, several criteria were set up. First of all, the system had to be entirely wireless. Therefore, the power consumption had to be as low as possible. Moreover, the program of requirements stated that the transmission distance had to be at least five meters. After searching for suitable wireless protocols for this assignment, the hardware had to be chosen. The SX1212, XBEE series II, ATmega128RFA1 and CC430xxxx were found as potential solutions. The same criteria that were subjected to the wireless protocols were applied to these hardware solutions as well. Furthermore, the ease of hardware implementation was added as well as the ease of software implementation. Additionally, the knowledge available at EEMCS about these solutions was appended to the criteria. The measurements had to be displayed after setting up the wireless communication. The measurements could be displayed on a website, an app or a computer screen. The measurements could have been stored locally as well as externally. Safety is one of the criteria used to choose a display solution. This was why locally storing the measurements was preferred. However, the recent popularity for apps was a criterion for choosing the method of displaying the information as well. The ZigBee solution was chosen, because it was most suited for this project. Rubee, UWB and Wi-Fi were abandoned, because those protocols do not meet the specifications. ZigBee uses less power than Z-Wave and therefore, is chosen above Z-Wave. The fact that former researchers encountered problems while setting up a connection between two Z-Wave modules was added to the argumentation. Bluetooth can have either a short range or a high outputpower to transmit. Since the “short range” was considered too short, Bluetooth was abandoned as well. Moreover, ZigBee had been developed to transmit a low amount of data in a low power consuming way. Hardware had to be chosen after finding a suitable protocol. The XBEE series II was chosen from the hardware solutions. A low amount of data had to be sent and the XBEE series II was the least power consuming of these solutions while sending a low amount of data. Moreover, the XBEE series II was the easiest to implement. There were several options to display the received data. Since the data had to be received by a computer, displaying it on a computer screen was chosen. The data was displayed in the console in which the program was written. Moreover, an internet connection is not mandatory. However, it was chosen to develop an app as well. This is because an app can be viewed anywhere at any time. The current running through the system was measured in order to check if the requirements were met. The system appeared to have an average current consumption of 50.8?A. This consumption would be sufficient for the system to run autonomously for a year. Furthermore, it was necessary to check if the system was able to transmit over at least 5 meters, since the program of requirements stated this demand. The measurements showed that the system was able to transmit over 40 meters, which was enough.ElektrotechniekElectronic Instumentation LaboratoryElectrical Engineering, Mathematics and Computer Scienc
Energy Management System for a Wireless Indoor Climate Sensor
No full textThe Electronic Instrumentation Lab at Delft University of Technology desired to have a demonstrator for low-power temperature and humidity sensors they developed, in the form of a wireless sensor node. This thesis presents the design of the energy management system of this node. The primary design goal was to allow the sensor systems to run for as long as possible, at least a year, without any kind of service or human intervention, doing so in indoor lighting conditions. Using the state of the art of such energy systems in sensor nodes, a concept consisting of energy storage combined with energy conditioning was generated. A single cell lithium-ion polymer battery and an ultra low quiescent current linear voltage regulator (the Texas Instruments TPS78233) were used to implement this concept. Switching voltage regulators with buck and buck-boost topologies were also considered, as well as combinations of linear and switching voltage regulators, but these ultimately turned out to be highly inefficient when the sensor is idle and the output current is in the order of microamperes. The lithium-ion polymer battery chemistry was chosen because it is widely available in high capacities, it has a relatively low self-discharge current and it can be charged. As the ultimate goal of this design was to let the sensor systems run for as long as possible, and not just a year, energy harvesting techniques were also researched. It was found that amorphous solar cells were the best option for this design, as this was the best commercially available technology for harvesting energy at low light levels at the time. A promising new solar cell technology for this purpose is the dye-sensitized solar cell, however, these were only available as do-it-yourself kits at the time, and project time constraints withheld the usage of this technology because of that. Energy harvesting based on radio-frequency electromagnetic waves was also considered, but it was found that this technology did not provide enough power within the size and budget constraints. As such, a secondary concept was generated, using a 100x50 mm amorphous solar panel by Sanyo Energy and a lithium-ion charger circuit based on the Maxim MAX17710. The charging circuit consists primarily of a largely integrated switching voltage regulator using the boost topology. Both of these systems were implemented on a single circuit board along with the other sensor systems, designed such that it was possible to switch between the two energy systems easily. When this circuit board was completed, measurements were done to determine the average output current of the charger under office light conditions. When it is assumed that these conditions last for about ten hours per day, the average current output was found to be approximately 45 ?A. Furthermore, the average supply current for the sensor was found to be 53.4 ?A. Using these numbers, the minimum capacity for the battery to run the system for a year was determined to be 1300 mAh when no harvesting system is used, and 213 mAh when the solar panel is used.Electronic Instrumentation LaboratoryElectrical EngineeringElectrical Engineering, Mathematics and Computer Scienc
A 30 ppm < 80 nJ Ring-Down-Based Readout Circuit for Resonant Sensors
No full textThis paper presents an energy-efficient readout circuit for micro-machined resonant sensors. It operates by briefly exciting the sensor at a frequency close to its resonance frequency, after which resonance frequency and quality factor are determined from a single ring-down transient. The circuit employs an inverter-based trans-impedance amplifier to sense the ring-down current, with a programmable feedback network to enable the readout of different resonant sensors. An inverter-based comparator with dynamically-adjusted threshold levels tracks the ring-down envelope to measure quality factor, and detects zero crossings to measure resonance frequency. The excitation frequency is dynamically adjusted to accommodate large resonance frequency shifts. Experimental results obtained with a prototype fabricated in 0.35 μm standard CMOS technology and three different SiN resonators are in good agreement with conventional impedance analysis. The prototype achieves a frequency resolution better than 30 ppm while consuming less than 80 nJ/meas from a 1.8 V supply, which is 7.8x less than the state-of-the-art.Accepted author manuscriptElectronic Instrumentatio
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