Ze Zhao

The Design and Evaluation of a Wireless Sensor Network for Mine Safety Monitoring

This paper describes a wireless sensor network for mine safety monitoring. Based on the characteristics of underground mine gallery and the requirements for mine safety monitoring, we proposed a distributed heterogeneous hierarchical mine safety monitoring prototype system, namely HHMSM This system is capable of monitoring methane concentration, and locating miner. We proposed a novel overhearing-based adaptive data collecting scheme which exploits the redundancy and correlation of the sampling readings in both time and space to reduce traffic and control overhead with a well-bounded offset error for large-scale sensor networks. This mechanism is easy to implement and low-cost compared to other more theoretically based mechanisms such as Kalman filter. Experimental results show that HHMSM achieves better performance on flexibility, correctness, coverage, and lifetime compared with other existing wireless mine safety monitoring systems.

EasiMed: A remote health care solution

An embedded remote health care system based on wireless sensor network technology was established. Firstly, a new system architecture was proposed which introduced a scalable wireless personal medical sensor network around humans body. Then the designs of several sensor node and the care base-station were presented. The wireless communication between the sensor nodes and the care base-station used IEEE 802.15.4/Zigbee standard whilst the care base-station and the remote central server was connected in one of the following ways, including computing network, GSM short messages and telephone modem. The system can be used for remote health care at home or in the hospitals

Design and implementation of an ASIC-based sensor device for WSN applications

The practical applications of wireless sensor networks require the sensor devices to be high in computation ability, low in power consumption, small in size, as well as competitive in cost. In addition, there are other particular attributes which require special consideration in sensor device design. These include, for example, the capabilities in protecting the embedded program from foreign intrusion and supporting efficient air-programming, which are very common requirements in many large-scale applications. In this paper, we describe the system architecture and design methodology of an ASCI-based sensor network device to meet those attributes for a class of applications. Compared with existing works, the unique features of the sensor device include: (1) a module-based extensible processor and co-processor cooperation architecture is designed with application-specific components to accelerate the signal collection, processing, and networking via hardware-software co-design to balance computation efficiency and design flexibility; (2) a program protection mechanism is developed based on un-resemble coder algorithm to protect the program data from being read out by system intruders so as to improve the security of the sensor device; (3) an air-programming component is proposed to enable an efficient remote programming which is a very common requirement in network deployment and maintenance. In this paper, we present the design, implementation, and evaluation of the prototype sensor device based on a general configurable FPGA platform for developing next-generation sensor devices. Initial results of the first version of prototype chip will also be introduced.

Demonstration of a WSN Application in Relic Protection and an Optimized System Deployment Tool

This paper presents an overview of our demonstration of a real application of a WSN system for relic protection applied in the Forbidden City of China. We briefly introduce the EasiNet hardware platform we have developed and the corresponding mesh-architecture of the system constructed. We present a sensor deployment optimization tool based on ant colony optimization technology (DT-ACO) to meet the requirements of network connectivity, sensing coverage and a minimized overall cost of the system. We describe a novel power-aware cross-layer scheme (PACS) to facilitate adjustable system lifetime and surveillance accuracy. We also show some detailed results of the application case.

Implementation and application of a multi-radio wireless sensor networks testbed

The authors propose EasiTest, a multi-radio testbed for heterogeneous wireless sensor networks (WSNs). Two types of sensor nodes, specifically, high-speed multi-radio node (EZ271) and low-speed single-radio node (EZ521) are developed. An administration platform is provided to monitor and control the testbed. EasiTest enjoys high flexibility, powerful processing capability and ease of expansion. EasiTest provides a powerful tool not only for the study and evaluation of large-scale, heterogeneous sensor networks, but also for quick prototyping of practical WSN applications. To demonstrate the capability of the testbed, the co-existence problem of IEEE 802.11 and IEEE 802.15.4 is studied. Guidelines are given on channel allocation and network parameter configuration to minimise the interference. In addition, to demonstrate the flexibility of the testbed, the authors evaluate robust opportunistic scheduling for ad hoc networks, a distributed opportunistic scheduling protocol, based on the testbed. The experimental results match with the simulation results very well.

A cyber physical networking system for monitoring and cleaning up blue-green algae blooms with agile sensor and actuator control mechanism on Lake Tai

Nowadays, the harmful blue-green algae blooms on lakes threaten the daily life of millions of people in China. We designed and developed a cyber physical networking system on Lake Tai for the monitoring and cleanup of the water blooms which is at work in Wuxi City, Jiangsu Province. We designed the sensor device and algorithm to monitor the order of severity of algae bloom. A GIS-based management website is built for the end user to monitor the whole system. In this paper, we focus on the agile sensor and actuator control (ASAC) mechanism to dispatch salvaging boats. The location area and the order of severity of a water bloom change rapidly with the climatic, the terrain and the sewage disposal system. The location and the capacity of salvaging boat are also in changing when the system is running. ASAC is designed to generate optimal dispatch plan in the changing environment. This mechanism also balances workloads among the boats and among the algae factories to achieve an overall high working efficiency. Through the tests in the real system, ASAC largely saved human resource and increased the work efficiency in the cleaning up process.

A multi-radio wireless P2P network testbed

Wireless peer-to-peer (P2P) networks have been widely studied in recent years. Testing and evaluating wireless P2P network protocols are challenging tasks because they require a powerful and flexible hardware platform and supervision interface. In this work, EZ270, a novel wireless node with multi-radio support is designed and developed. Based on EZ270, a general purpose wireless P2P network testbed with user-friendly supervision features is built. The functionality and effectiveness of the wireless nodes and of the testbed are demonstrated.

Data-Driven Soft Sensor Modeling for Algal Blooms Monitoring

Currently, salvage is considered as an effective way for protecting ecosystems of inland water from toxin-producing algal blooms. Yet, the magnitude of algal blooms, which is the essential information required for dispatching salvage boats, cannot be estimated accurately with low cost in real time. In this paper, a data-driven soft sensor is proposed for algal blooms monitoring, which estimates the magnitude of algal blooms using data collected by inexpensive water quality sensors as input. The modeling of the soft sensor consists of two steps: 1) magnitude calculation and 2) regression model training. In the first step, we propose an active learning strategy to construct high-accuracy image classification model with ~50 % less labeled data. Based on this model, we design a new algorithm that recognizes algal blooms and calculates the magnitude using water surface pictures. In the second step, we propose to use Gaussian process to train the regression model that maps the multiparameter water quality sensor data to the calculated magnitude of algal blooms and learn the parameters of the model automatically from the training data. We conduct extensive experiments to evaluate our modeling method, AlgaeSense, based on over 200 000 heterogeneous sensor data records collected in four months from our field-deployed sensor system. The results indicate that the soft sensor can accurately estimate the magnitude of algal blooms in real time using data collected by just three kinds of inexpensive water quality sensors.

A Channel Allocation Scheme to Mitigate Wifi Interference for Wireless Sensor Networks: A Channel Allocation Scheme to Mitigate Wifi Interference for Wireless Sensor Networks

Wireless sensor networks will suffer severe performance degradation in communication reliability and throughput when interfered by co-located Wifi devices.When multiple sensor networks with different priority are interfered by Wifi devices,it is of great significance to allocate channels according to their priority as well as take into consideration the overall communication reliability and throughput.To address this problem,a channel allocation scheme to mitigate Wifi interference,called EasiCAP(Channel Allocation for wireless sensor networks with Priority),is presented.The scheme employs an external interference model,which is based on interference signal strength and activity ratio,to measure Wifi interference in each channel of sensor networks.In addition,a receiver-centric interference model is used to gauge internal interference amongst different sensor networks.Based on the measurements of external interference and internal interference,each sensor network independently selects its working channel in real time via a localized greedy algorithm in order to assign channels according to priority and also reduce the overall interference of all sensor networks as much as possible.Then,the sensor network performs one of the three operations,i.e.,channel keeping,channel swapping,and channel preempting,based on the channel selection decision.Testbed experiments and simulations are conducted to verify the effectiveness of the proposed scheme.The experimental results demonstrate that EasiCAP can provide differentiated communication reliability and throughput corresponding to the network priority.Also,it has higher average communication reliability and throughput than existing schemes.Furthermore,it does not introduce significant overhead.

A heterogeneous peer-to-peer network testbed

In this paper, we describe a heterogeneous peer-to-peer network testbed, which is developed as part of a joint research project to investigate novel resource discovery and content distribution protocols in a heterogeneous wired/wireless environment. We describe the testbed requirements, the testbed architecture, the multi-functional wireless node, and the software architecture. We also describe some of the proposed protocols to be developed and tested on the testbed.