With the development of analog integrated circuits technology and due to the complexity, and various types of faults that occur in analog integrated circuits, fault detection is a new idea, has been studied in recent decades. In this paper a three amplifier state variable filter is used as circuit under test (CUT) and, a hybrid neural network is proposed for soft fault diagnosis of the CUT. Genetic algorithm (GA) has the powerful ability of searching the global optimal solution, and back propagation (BP) algorithm has the feature of rapid convergence on the local optima. The hybrid of two algorithm will improve the evolving speed of neural network. GA-BP scheme adopts GA to search the optimal combination of weights in the solution space, and then uses BP algorithm to obtain the accurate optimal solution quickly. Experiment results show that the proposed GA-BP scheme is more efficient and effective than BP algorithm. 相似文献
The peak III/I ratio of pyrene monomer fluorescence was used to characterize surface-induced insulin denaturation and aggregation. An indicator of the hydrophobicity of pyrene's microenvironment, the IIM ratio can be used to study self-association of amphipathic molecules. In sodium lauryl sulfate (NaLS), the III/I ratio was 0.71 below the critical micelle concentration (CMC) and increased to 0.98 when the concentration was above the CMC. When insulin was placed in a polystyrene cuvet for 2 days at 37°C, the IWI ratio decreased from 0.84 to 0.78. The decrease in III/I ratio corresponds to surface-induced denaturation of insulin which exposed pyrene to a more polar environment. Increasing the duration of incubation for up to 12 days increased the III/I ratio to 1.06. Increased hydrophobicity of pyrene's environment correlates with the self-association of insulin. Once the aggregates reached a critical size, they began precipitating as was evident by an increase in the turbidity (absorbance at 600 nm) of solution. The results of this study support previous hypothesis that the aggregation and precipitation of insulin at hydrophobic interfaces is initiated by adsorption and surface-induced denaturation. 相似文献
The modulation of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) biosynthesis by sulfur-substituted fatty acid
analogues has been investigated in rats. We have compared the effects of two non-β-oxidizable fatty acid analogues, 3-thiadicarboxylic
acid and tetradecylthioacetic acid, which induce proliferation of peroxisomes, with those of the analogue tetradecylthiopropionic
acid, which is a weak peroxisome proliferator. Repeated administration of 3-thiadicarboxylic acid for seven days resulted
in increased hepatic concentrations of both PC and PE, but the PC/PE ratio was decreased. PC synthesis was increased, as evidenced
by increased incorporation of [3H]choline into PC and an increased activity of cytidinetriphosphate (CTP): phosphocholine cytidylyltransferase. This was accompanied
by a reduction in the pool sizes of choline and phosphocholine. TheS-adenosylmethione/S-adenosylhomocysteine ratio (AdoMet/AdoHcy) was marginally affected, indicating no increase in the rate of methylation of
PE to PC. Administration of tetradecylthioacetic acid also resulted in increased hepatic phospholipid levels, increased AdoMet/AdoHcy
ratios and in slightly elevated activity of CTP:phosphocholine cytidylyltransferase. The most striking effect observed after
tetradecylthiopropionic acid treatment was the development of fatty liver. The activity of CTP:phosphocholine cytidylyltransferase
and the incorporation of [3H]choline into PC was reduced compared to 3-thiadicarboxylic acid treatment. Although the rate of methylation of PE seemed
to be increased at an elevated AdoMet/AdoHcy ratio, this resulted in only minor changes in the hepatic PC and PE levels, and
the PC/PE ratio remained unchanged. Furthermore, the hepatic levels of choline and phosphocholine were reduced in these rats.
The activities of the two enzymes competing for choline in the liver, choline kinase and choline dehydrogenase were changed
in opposite directions, with the activity of choline kinase increasing approximately 1.5-fold. In addition, it was found that
the level of homocysteine was elevated in the liver of tetradecylthiopropionic acid-treated rats. The possibility is discussed
that this reflects a reduced flux of choline through the oxidative pathway in the liver. In tetradecylthiopropionic acid-treated
rats, there seemed to be a coordinated regulation of the two pathways for PC biosynthesis, with an increase in the methylation
of PE to PC and a reduced synthesisvia the CDPcholine pathway. The increase in PC observed in rats treated with 3-thiadicarboxylic acid and tetradecylthioacetic
acid suggests that increased PC synthesis is linked to peroxisome proliferation. 相似文献
High-pressure phases of CaCO3, namely aragonite, calcite II, and possibly calcite III, were synthesized in air by exposing 10- to 20-μm-size particles of CaCO3 (calcite I phase) to a CO2 laser radiation at short pulse lengths (≤0.1 ms). The process, therefore, has the same effect as exposing the particles to at least several hundred megapascals pressure. Processing at higher pulse lengths resulted in the decomposition of CaCO3 to CaO and CO2. The extent of decomposition increased with increasing pulse length. 相似文献
The first formal immunisation schedule for the delivery of triple (DTP) vaccine was drawn up in November 1960. Since 1960 there have been many changes to the immunisation schedule, with a further change proposed for 1996. These changes have been in response to new vaccine development and better understanding of vaccine immunology. Further changes are certain. 相似文献
Wireless sensor networks (WSN) consist of hundreds of miniature sensor nodes to sense various events in the surrounding environment and report back to the base station. Sensor networks are at the base of internet of things (IoT) and smart computing applications where a function is performed as a result of sensed event or information. However, in resource‐limited WSN authenticating a remote user is a vital security concern. Recently, researchers put forth various authentication protocols to address different security issues. Gope et al presented a protocol claiming resistance against known attacks. A thorough analysis of their protocol shows that it is vulnerable to user traceability, stolen verifier, and denial of service (DoS) attacks. In this article, an enhanced symmetric key‐based authentication protocol for IoT‐based WSN has been presented. The proposed protocol has the ability to counter user traceability, stolen verifier, and DoS attacks. Furthermore, the proposed protocol has been simulated and verified using Proverif and BAN logic. The proposed protocol has the same communication cost as the baseline protocol; however, in computation cost, it has 52.63% efficiency as compared with the baseline protocol. 相似文献
Widespread growth of cities, the association of trace metals with urban runoff, and the potentially deleterious effect of metals on aquatic ecology have made it important to understand the distribution and transport of metals through surface water channel networks. The Don River in Toronto, Canada has been identified as an Area of Concern for pollution to Lake Ontario, with historically high levels of metal contamination. Sampling programs are sparse, therefore a model is needed to understand the spatial and temporal variability of metals in the river network. The objectives of the current study are to: i) describe the sampled spatial and temporal variability of metals in the Don River and ii) develop a modelling strategy to describe within flood metal transport dynamics. A model setup tool is developed that links Storm Water Management Model (SWMM) with the Environmental Fluid Dynamics Code (EFDC) to allow a seamless transition from catchment hydrology to in-stream hydraulic and chemical processes. Results show that lead pollution in the Don River is decreasing, likely as a result of policy changes and sediment dredging in the mouth of the river. However, zinc and copper pollution are increasingly problematic, with copper exceeding recommended lower guidelines, particularly during floods. Model results confirm that most of the sediment and metals are transported in relatively short bursts within longer flood durations and are stored in depositional hotspots within the Lower Don River. A better monitoring strategy is needed to understand and more accurately parametrize these processes in an urban river system. 相似文献
The growing prevalence of droughts and water scarcity have increased the importance of operating dam and reservoir systems efficiently. Several methods based on algorithms have been developed in recent years in a bid to optimize water release operation policy, in order to overcome or minimize the impact of droughts. However, all of these algorithms suffer from some weaknesses or drawbacks – notably early convergence, a low rate of convergence, or trapping in local optimizations – that limit their effectiveness and efficiency in seeking to determine the global optima for the operation of water systems. Against this background, the present study seeks to introduce and test a Hybrid Algorithm (HA) which integrates the Gravitational Search Algorithm (GSA) with the Particle Swarm Optimization Algorithm (PSOA) with the goal of minimizing irrigation deficiencies in a multi-reservoir system. The proposed algorithm was tested for a specific important multi-reservoir system in Iran: namely the Golestan Dam and Voshmgir Dam system. The results showed that applying the HA could reduce average irrigation deficiencies for the Golestan Dam substantially, to only 2 million cubic meters (MCM), compared to deficiency values for the Genetic Algorithm (GA), PSOA and GSA of 15.1, 6.7 and 5.8 MCM respectively. In addition, the HA performed very efficiently, reducing substantially the computational time needed to achieve the global optimal when compared with the other algorithms tested. Furthermore, the HA showed itself capable of assuring a high volumetric reliability index (VRI) to meet the pattern of water demand downstream from the dams, as well as clearly outperforming the other algorithms on other important indices. In conclusion, the proposed HA seems to offer considerable potential as an optimizer for dam and reservoir operations world-wide.
Traditional relational database systems handle data by dividing their memory into sections such as a buffer cache and working memory, assigning a memory budget to each section to efficiently manage a limited amount of overall memory. They also assign memory budgets to memory-intensive operators such as sorts and joins and control the allocation of memory to these operators; each memory-intensive operator attempts to maximize its memory usage to reduce disk I/O cost. Implementing such memory-intensive operators requires a careful design and application of appropriate algorithms that properly utilize memory. Today's Big Data management systems need the ability to handle large amounts of data similarly, as it is unrealistic to assume that truly big data will fit into memory. In this article, we share our memory management experiences in Apache AsterixDB, an open-source Big Data management software platform that scales out horizontally on shared-nothing commodity computing clusters. We describe the implementation of AsterixDB's memory-intensive operators and their designs related to memory management. We also discuss memory management at the global (cluster) level. We conducted an experimental study using several synthetic and real datasets to explore the impact of this work. We believe that future Big Data management system builders can benefit from these experiences. 相似文献