1,391 research outputs found

    CeO2 based catalysts for the treatment of propylene in motorcycle's exhaust gases

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    In this work, the catalytic activities of several single metallic oxides were studied for the treatment of propylene, a component in motorcycles' exhaust gases, under oxygen deficient conditions. Amongst them, CeO2 is one of the materials that exhibit the highest activity for the oxidation of C3H6. Therefore, several mixtures of CeO2 with other oxides (SnO2, ZrO2, Co3O4) were tested to investigate the changes in catalytic activity (both propylene conversion and CO2 selectivity). Ce0.9Zr0.1O2, Ce0.8Zr0.2O2 solid solutions and the mixtures of CeO2 and Co3O4 was shown to exhibit the highest propylene conversion and CO2 selectivity. They also exhibited good activities when tested under oxygen sufficient and excess conditions and with the presence of co-existing gases (CO, H2O)

    Parameter Estimation and Predictive Speed Control of Chopper-Fed Brushed DC Motors

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    This paper presents an effective speed control method for brushed DC motors fed by a DC chopper using the concept of Finite Control Set-Model Predictive Control (FCS-MPC). As this control algorithm requires the parameters of the controlled object, the estimation of motor parameters is first performed by using two types of data. The first data includes the output speed response corresponding to the step input voltage to obtain the transfer function in the no-load regime. The second data consists of the motor speed and armature current when a load torque is applied to the motor shaft. The discrete-time equation of the motor armature circuit is used to obtain the future values of the armature circuit current and the motor speed. A cost function is defined based on the difference between the reference and predicted motor speed. The optimal switching states of the DC chopper are selected corresponding to the maximum value of the cost function. The performance of the proposed speed control algorithm is validated on an experimental system. The simulation and experimental results obtained show that the MPC controller can outperform the conventional proportional-integral (PI) controller

    Organic Fertilizer Production and Application in Vietnam

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    Crop production is an important subsector of Vietnam’s agriculture, has an impressive achievement in last 30 years and based on the intensive production with increasing use of chemical fertilizer and pesticide. Consequences are the negative effects on environment and human health and food safety. Organic agriculture has become a trend worldwide and is developing rapidly in the world. In Vietnam the certified organic farming area has expanded since 2012. Organic market revenue in Vietnam is estimated to be at $132.15 million a year. Most Vietnamese certified organic products are exported to international markets. Organic agriculture using organic fertilizer is one of Vietnam government’s priorities. Vietnam already produced organic fertilizer from different materials by using different production technologies, but the production capacity is small and does not meet the demand for organic agriculture. Vietnam government encourages, promotes the organic fertilizer production, application and has the policy to develop the organic fertilizer in Vietnam

    Food and biosecurity: livestock production and towards a world free of foot-and-mouth disease

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    A key challenge for global livestock production is the prevalence of infectious animal diseases. These diseases result in low productivity in meat and dairy production, culled animals, and significant barriers to trade and lost income from meat and meat products. Foot-and-mouth disease (FMD) affects both developing countries, where it is often endemic and very costly, and developed countries where incursions result in considerable economic losses in the order of billions of dollars per year. In some cases, production levels of pork meat in developed countries have still not recovered to levels prior to past disease incursions, more than a decade ago. In developing countries, the export of animal products has exhibited sluggish growth for decades, constrained by ongoing animal disease problems. We make three contributions. First, we provide an overview of worldwide meat production, consumption and trade in the context of FMD. Second, we provide insights into the economics of biosecurity measures and how these activities should be optimally designed to enhance livestock production. Third, we analyse a case study of an FMDendemic country, Vietnam, which has been trying to achieve FMD-free status for some time. Lessons learnt from this case study shed light on the challenges in achieving FMD-free status in developing countries, which is useful for a global FMD control strategy and the promotion of world food security.Partial funding from the Centre of Excellence for Biosecurity Risk Analysis at the University of Melbourne is also greatly appreciated. This paper was part of a workshop sponsored by the OECD Co-operative Research Programme on Biological Resource Management for Sustainable Agricultural Systems

    Performance of cluster-based cognitive multihop networks under joint impact of hardware noises and non-identical primary co-channel interference

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    In this paper, we evaluate outage probability (OP) of a cluster-based multi-hop protocol operating on an underlay cognitive radio (CR) mode. The primary network consists of multiple independent transmit/receive pairs, and the primary transmitters seriously cause co-channel interference (CCI) to the secondary receivers. To improve the outage performance for the secondary network under the joint impact of the CCI and hardware imperfection, we employ the best relay selection at each hop. Moreover, the destination is equipped with multiple antennas and uses the selection combining (SC) technique to enhance the reliability of the data transmission at the last hop. For performance evaluation, we first derive an exact formula of OP for the primary network which is used to calculate the transmit power of the secondary transmitters. Next, an exact closed-form expression of the end-to-end OP for the secondary network is derived over Rayleigh fading channels. We then perform Monte-Carlo simulations to validate the derivations. The results present that the CCI caused by the primary operations significantly impacts on the outage performance of the secondary network

    A Machine Learning-based Approach to Vietnamese Handwritten Medical Record Recognition

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    Handwritten text recognition has been an active research topic within computer vision division. Existing deep-learning solutions are practical; however, recognizing Vietnamese handwriting has shown to be a challenge with the presence of extra six distinctive tonal symbols and extra vowels. Vietnam is a developing country with a population of approximately 100 million, but has only focused on digitalization transforms in recent years, and so Vietnam has a significant number of physical documents, that need to be digitized. This digitalization transform is urgent when considering the public health sector, in which medical records are mostly still in hand-written form and still are growing rapidly in number. Digitization would not only help current public health management but also allow preparation and management in future public health emergencies. Enabling the digitalization of old physical records will allow efficient and precise care, especially in emergency units. We proposed a solution to Vietnamese text recognition that is combined into an end-to-end document-digitalization system. We do so by performing segmentation to word-level and then leveraging an artificial neural network consisting of both convolutional neural network (CNN) and a long short-term memory recurrent neural network (LSTM) to propagate the sequence information. From the experiment with the records written by 12 doctors, we have obtained encouraging results of 6.47% and 19.14% of CER and WER respectively

    A pillanat sterilezett tej fehérjéinek változása tárolás során

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    Die Änderung der Proteine von zur begrenzten Lagerung „sterilisierten” Milchproben wurde untersucht. Die in einer mit einem in Gegenstrom arbeitenden Wärmeaustauscher versehenen Pasteurisiereinrichtung bei 130 °C und 140 °C geheizten Proben von Milchgemischen wurden unter verschiedenen Bedingungen (hei 10, 20 bzw. 30 °C 10, 20, 25 und 30 Tage lang) gelagert. Es wurde sowohl mit den sensorischen wie auch mit der durch Polyacrylamid gel-Elektrophorese bzw. mit dem Pro-Milk Gerät durchgeführten Proteinuntersuchungen festgestellt, dass - besonders die bei höherer Temperatur „sterilisierte” - Milch einige Wochen land sogar bei einer schwach gekühlten Lagerung haltbar ist. Natürlich muss man auch in diesem Fall die Kühlkette bis zum Verbrauch sichern. Changes of proteins of milk samples sterilized for a limited storage were investigates. Samples of miqed milk heated at 130 °C and 140 °C in a pasteurizer equipped with a counter-current heat exchanger were stored under various conditions (at 10, 20 or 30 °C 10, 20, 25 and 30 days). Protein investigations both by sensory tests and by polyacrylamide-gel electrophoresis and with the Pro-Milk proved that particularly the milk „sterilized” at higher temperature can be stored for some weeks even on storage in a slightly cooled area. Obviously the cooling chain must be ensured in this case until the milk is consumed
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