摘要 :
Wireless Sensor Networks have demonstrated successful applications for both civil and military tasks in recent years. However,sensor networks are susceptible to jamming attacks because they are randomly deployed in open and unprot...
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Wireless Sensor Networks have demonstrated successful applications for both civil and military tasks in recent years. However,sensor networks are susceptible to jamming attacks because they are randomly deployed in open and unprotected environments,and sensor nodes are always resource-limited. Therefore,it is necessary to utilize effective mechanisms to protect sensor networks against malicious jamming. In this paper,we propose a noncooperative zero-sum game theoretic framework for jamming detection and avoidance framework integrated for single-hop wireless sensor networks. Furthermore,we provide two utility function types and analyze the Nash Equilibrium of the proposed zero-sum game. Based on the analyzed results,our scheme can prevent jamming attacks on sensor networks efficiently.
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摘要 :
Wireless Sensor Networks have demonstrated successful applications for both civil and military tasks in recent years. However,sensor networks are susceptible to jamming attacks because they are randomly deployed in open and unprot...
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Wireless Sensor Networks have demonstrated successful applications for both civil and military tasks in recent years. However,sensor networks are susceptible to jamming attacks because they are randomly deployed in open and unprotected environments,and sensor nodes are always resource-limited. Therefore,it is necessary to utilize effective mechanisms to protect sensor networks against malicious jamming. In this paper,we propose a noncooperative zero-sum game theoretic framework for jamming detection and avoidance framework integrated for single-hop wireless sensor networks. Furthermore,we provide two utility function types and analyze the Nash Equilibrium of the proposed zero-sum game. Based on the analyzed results,our scheme can prevent jamming attacks on sensor networks efficiently.
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Thermoelectric generators (TEG) are widely used in many industries. The voltage and output power of TEG chips are critical indicators to evaluate the performance of TEGs. The conventional method is to directly test the output volt...
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Thermoelectric generators (TEG) are widely used in many industries. The voltage and output power of TEG chips are critical indicators to evaluate the performance of TEGs. The conventional method is to directly test the output voltage and power of the whole TEG chip that contains 127 pairs of PN (P- and N-type) legs (127-PN-TEG). However, the assembling of these PN legs is very time-consuming. In order to reduce experimental time and the consumption of TEG materials, we proposed an experimental method. We developed the test apparatus for the rap id evaluation of TEG performance using a TEG chip with a single pair of PN legs (1-PN-TEG). We made several 1-PN-TEGs and 127-PN-TEGs using the same thermoelectric material (bismuth telluride). We then measured the voltage and the power of these 1-PN-TEGs and 127-PN-TEGs, respectively. The experimental results were compared and analyzed. The comparison showed that the voltage of 127-PN-TEG is equal to the voltage of 1-PN-TEG times 127, which implies that we could use the test data of 1-PN-TEG to evaluate the performance of 127-PN-TEG. Using the experimental device developed in this paper, we also studied the effects of the PN leg area (cross-sectional area of PN legs) and the pressure applied over the TEGs on the output power of 1-PN-TEG. The experimental results showed that the power per unit area decreases with an increase in the 1-PN-TEG's PN leg area when the temperature difference between the hot and cold sides was constant. Under a specific temperature difference conditions, the open-circuit voltage and the output power will increase with the pressure applied on the TEG chips.
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Large cities in China are building extensive rail transit systems in combination with transitoriented
development (TOD) in suburban areas, so that public transportation can play a leading
role in supporting rapid urban expansion...
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Large cities in China are building extensive rail transit systems in combination with transitoriented
development (TOD) in suburban areas, so that public transportation can play a leading
role in supporting rapid urban expansion. Shanghai has been a leader in this planning approach.
Its experience can be valuable for other cities that are facing similar pressures of urbanization,
suburbanization and motorization while striving to improve livability and reduce GHG emission.
To gain useful insights from Shanghai, we conducted a travel survey of residents in a recently
developed suburban metro station area to examine how the city's Mass Rapid Transit (MRT) has
influenced residents' travel and car ownership. Applying statistical methods, including logistic
regression, we found that: (1) the MRT is generally adequate in supporting the station area's
economic relationships with the central city and local employment locations, (2) a high
percentage of residents intended to commute by the MRT when they moved to the suburban
station area, and their original intention has positively influenced their current travel and car
ownership, and (3) rail transit may help temporarily reduce the pace of motorization among
households near suburban metro stations by delaying car purchase and lowering the probability
of car use in commuting. However, we also found that car ownership has been increasing quite
rapidly despite the positive effects of a much expanded and improved metro system, and that
once a person owns a car, s/he will most likely drive to work.
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摘要 :
Large cities in China are building extensive rail transit systems in combination with transitoriented
development (TOD) in suburban areas, so that public transportation can play a leading
role in supporting rapid urban expansion. ...
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Large cities in China are building extensive rail transit systems in combination with transitoriented
development (TOD) in suburban areas, so that public transportation can play a leading
role in supporting rapid urban expansion. Shanghai has been a leader in this planning approach.
Its experience can be valuable for other cities that are facing similar pressures of urbanization,
suburbanization and motorization while striving to improve livability and reduce GHG emission.
To gain useful insights from Shanghai, we conducted a travel survey of residents in a recently
developed suburban metro station area to examine how the city's Mass Rapid Transit (MRT) has
influenced residents' travel and car ownership. Applying statistical methods, including logistic
regression, we found that: (1) the MRT is generally adequate in supporting the station area's
economic relationships with the central city and local employment locations, (2) a high
percentage of residents intended to commute by the MRT when they moved to the suburban
station area, and their original intention has positively influenced their current travel and car
ownership, and (3) rail transit may help temporarily reduce the pace of motorization among
households near suburban metro stations by delaying car purchase and lowering the probability
of car use in commuting. However, we also found that car ownership has been increasing quite
rapidly despite the positive effects of a much expanded and improved metro system, and that
once a person owns a car, s/he will most likely drive to work.
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摘要 :
An experimental rig of a combined refrigeration/power generation system was built and investigated.This rig uses an ammonia–water binary working fluid,is driven by low-grade heat,and can function under the absorption refrigeratio...
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An experimental rig of a combined refrigeration/power generation system was built and investigated.This rig uses an ammonia–water binary working fluid,is driven by low-grade heat,and can function under the absorption refrigeration model and absorption power generation model.When the system was operated under the refrigeration model,the temperatures of the ethylene glycol solution that entered and exited the evaporator were –5.28 oC and –9.07 oC,respectively.The cooling output was 11.67 kW,and the corresponding coefficient of performance was 0.465.When the system was operated under the power generation model,the temperature and pressure of the turbine inlet were 94.7 oC and 8.55 bar,respectively.The turbine outlet pressure was 1.79 bar,the net power output was 1.02 kW(after 1 kW of power consumed by the solution pump was reduced),and the corresponding heat-to-power conversion efficiency was 3.98％.
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摘要 :
An experimental rig of a combined refrigeration/power generation system was built and investigated.This rig uses an ammonia–water binary working fluid,is driven by low-grade heat,and can function under the absorption refrigeratio...
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An experimental rig of a combined refrigeration/power generation system was built and investigated.This rig uses an ammonia–water binary working fluid,is driven by low-grade heat,and can function under the absorption refrigeration model and absorption power generation model.When the system was operated under the refrigeration model,the temperatures of the ethylene glycol solution that entered and exited the evaporator were –5.28 oC and –9.07 oC,respectively.The cooling output was 11.67 kW,and the corresponding coefficient of performance was 0.465.When the system was operated under the power generation model,the temperature and pressure of the turbine inlet were 94.7 oC and 8.55 bar,respectively.The turbine outlet pressure was 1.79 bar,the net power output was 1.02 kW(after 1 kW of power consumed by the solution pump was reduced),and the corresponding heat-to-power conversion efficiency was 3.98％.
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With the development of the Internet of Things (IOT) technology, a large number of sensor data have been produced. Due to the complex acquisition environment and transmission condition, anomalies are prevalent. Sensor data is a ki...
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With the development of the Internet of Things (IOT) technology, a large number of sensor data have been produced. Due to the complex acquisition environment and transmission condition, anomalies are prevalent. Sensor data is a kind of typical time series data, its anomaly refers to not only outliers, but also the anomaly of continuous data fragments, namely anomaly patterns. To achieve anomaly pattern detection on sensor data, the characteristics of sensor data are analyzed including temporal correlation, spatial correlation and high dimension. Then based on these characteristics and the real-time processing requirements of sensor data, a sensor data oriented anomaly pattern detection approach is proposed in this paper. In the approach, the frequency domain features of sensor data are obtained by Fast Fourier Transform, the dimension of the feature space is reduced by describing frequency domain features with statistical values, and the high-dimensional sensor data is processed in time on the basis of Isolation Forest algorithm. In order to verify the feasibility and effectiveness of the proposed approach, experiments are carried out on the open dataset IBRL. The experimental results show that the approach can effectively identify the pattern anomalies of sensor data, and has low time cost while ensuring the high accuracy.
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摘要 :
With the development of the Internet of Things (IOT) technology, a large number of sensor data have been produced. Due to the complex acquisition environment and transmission condition, anomalies are prevalent. Sensor data is a ki...
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With the development of the Internet of Things (IOT) technology, a large number of sensor data have been produced. Due to the complex acquisition environment and transmission condition, anomalies are prevalent. Sensor data is a kind of typical time series data, its anomaly refers to not only outliers, but also the anomaly of continuous data fragments, namely anomaly patterns. To achieve anomaly pattern detection on sensor data, the characteristics of sensor data are analyzed including temporal correlation, spatial correlation and high dimension. Then based on these characteristics and the real-time processing requirements of sensor data, a sensor data oriented anomaly pattern detection approach is proposed in this paper. In the approach, the frequency domain features of sensor data are obtained by Fast Fourier Transform, the dimension of the feature space is reduced by describing frequency domain features with statistical values, and the high-dimensional sensor data is processed in time on the basis of Isolation Forest algorithm. In order to verify the feasibility and effectiveness of the proposed approach, experiments are carried out on the open dataset IBRL. The experimental results show that the approach can effectively identify the pattern anomalies of sensor data, and has low time cost while ensuring the high accuracy.
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摘要 :
Image saliency detection has achieved great improvements in last several years as the development of convolutional neural networks (CNN).But it is still difficult and challenging to get clear boundaries of salient objects.The main...
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Image saliency detection has achieved great improvements in last several years as the development of convolutional neural networks (CNN).But it is still difficult and challenging to get clear boundaries of salient objects.The main reason is that current CNN based saliency detection approaches cannot learn the structural information of salient objects well.Thus, to address this problem, this paper proposes a deep convolutional network with low-level feature enhanced for image saliency detection.Several shallow sub-networks are adopted to capture various low-level information with heuristic guidance separately, and the guided features are fused and fed into the following network for final inference.This strategy can help to enhance the spatial information in low-level features and further improve the accuracy in boundary localization.Extensive evaluations on five benchmark datasets demonstrate that the proposed method outperforms the state-of-the-art approaches in both accuracy and efficiency.
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