Keypoints-based approaches have shown to be promising for retinal image registration, which superimpose two or more images from different views based on keypoint detection and description. However, existing approaches suffer from ineffective keypoint detector and descriptor training. Meanwhile, the non-linear mapping from 3D retinal structure to 2D images is often neglected. In this paper, we propose a novel learning-based junction detection approach for retinal image registration, which enhances both the keypoint detector and descriptor training. To improve the keypoint detection, it uses a multi-task vessel detection to regularize the model training, which helps to learn more representative features and reduce the risk of over-fitting. To achieve effective training for keypoints description, a new constrained negative sampling approach is proposed to compute the descriptor loss. Moreover, we also consider the non-linearity between retinal images from different views during matching. Experimental results on FIRE dataset show that our method achieves mean area under curve of 0.850, which is 12.6% higher than 0.755 by the state-of-the-art method. All the codes are available at https://github.com/samjcheng/SuperJunction.

Destination prediction based on the partial trajectory of a moving vehicle is vital for urban mobility applications. Recent research efforts focus on improving the prediction accuracy by incorporating more spatio-temporal semantics through complex model architectures, which inevitably impact the generalization and scalability due to ad-hoc hyper-parameters and heavier computations. In the present study, we propose a novel Location Recommendation System for Destination Prediction, LRS4DP. Through an integrated design of several technologies (map-matching, deep learning and recommender system), LRS4DP provides an end-to-end solution for destination prediction based on input trajectories and road network configurations. By adopting a node-based spatial discretization scheme through map-matching, LRS4DP is able to adapt according to the local road network density and generalize to different urban layouts. As compared to the state-of-the-art algorithms, our proposed Top-K formulation based on individual road nodes leads to fundamentally better spatial precision and prediction accuracy even with simple model architectures. We further designed the offline training and online serving as a location recommendation system to achieve better scalability and flexible trade-off between performance and run-time. The experimental evaluation of two real-world taxi datasets demonstrates the generalization of LRS4DP under different urban scales and layouts. The LRS4DP framework is also generically applicable for location prediction tasks (e.g., next location and passing-by location predictions) and capable to support various downstream transportation and location-based service applications.

Many well-established anomaly detection methods use the distance of a sample to those in its local neighbourhood: so-called `local outlier methods', such as LOF and DBSCAN. They are popular for their simple principles and strong performance on unstructured, feature-based data that is commonplace in many practical applications. However, they cannot learn to adapt for a particular set of data due to their lack of trainable parameters. In this paper, we begin by unifying local outlier methods by showing that they are particular cases of the more general message passing framework used in graph neural networks. This allows us to introduce learnability into local outlier methods, in the form of a neural network, for greater flexibility and expressivity: specifically, we propose LUNAR, a novel, graph neural network-based anomaly detection method. LUNAR learns to use information from the nearest neighbours of each node in a trainable way to find anomalies. We show that our method performs significantly better than existing local outlier methods, as well as state-of-the-art deep baselines. We also show that the performance of our method is much more robust to different settings of the local neighbourhood size.

Detecting anomalies is an important task in a wide variety of applications and domains. Deep learning methods have achieved state-of-the-art performance in anomaly detection in recent years; unsupervised methods being particularly popular. However, deep learning methods can be fragile to small perturbations in the input data. This can be exploited by an adversary to deliberately hinder model performance; an adversarial attack. This phenomena has been widely studied in the context of supervised image classification since its discovery, however such studies for an anomaly detection setting are sorely lacking. Moreover, the plethora of defense mechanisms that have been proposed are often not applicable to unsupervised anomaly detection models. In this work, we study the effect of adversarial attacks on the performance of anomaly-detecting autoencoders using real data from a Cyber physical system (CPS) testbed with intervals of controlled, physical attacks as anomalies. An adversary would attempt to disguise these points as normal through adversarial perturbations. To combat this, we propose the Approximate Projection Autoencoder (APAE), which incorporates two defenses against such attacks into a general autoencoder. One of these involves a novel technique to improve robustness under adversarial impact by optimising latent representations for better reconstruction outputs.

There are numerous ways to monitor business activities, but the most effective way is by adopting data-driven decision-making processes and technologies to enable the corporate entities to monitor and measure performance KPIs. Dashboards are commonly used as the main supporting tool for presenting analytical results. However, current approaches have some limitations. Since data sources are usually transformed and materialized during the design phase, end users of typical dashboards can only perform simple filtering and layout changes in most cases. In this work, we introduce a flexible qualitative data analytics dashboard framework called Cookbook. The main novelty of our approach is that we achieve a highly customizable dashboard framework by segregating data during design phase, and materializing data during execution phase.

Internet of Things (IoT) is an emerging technological innovation and it could potentially changing the way people work, live and engage with devices. However, interaction with IoT devices through tangible user interface hasn't been getting much attention, particularly in the smart city domain. In this paper, we present a new urban scenario planning tool by introducing a new IoT based geospatial tangible user interface (GTUI). We discuss its advantages and disadvantages in the context of urban planning. We demonstrate three use cases where public and city planner can be benefited through the integration of IoT and tangible user interface.

Probe vehicle data, also known as floating car data or connected vehicle data, is the data collected from GPS-enabled sensors on vehicles. With the advancement in wireless communications and localization technologies, more and more vehicles are expected to be equipped with such sensors. Existing studies only focus on using small-scale probe vehicle data. In this paper, we are interested in developing a real-time parallel stream processing framework to extract traffic flow KPIs from large-scale probe vehicle data. The developed framework is implemented using Apache Storm on Amazon AWS, and can process one million probe vehicle messages per second. Various design considerations, such as data partition and delay processing are discussed. To evaluate the performance of stream processing framework, simulated probe vehicle data based on the actual traffic flows in Jurong Lake District (JLD) of Singapore, is generated using the microscopic simulation software VISSIM. The JLD data is replicated multiple times to represent the one million population of vehicles in Singapore. GPS errors and communication delays are added to represent the real situations before the data is fed to stream processing module. The estimated KPIs from our stream processing model are validated against the ground truth values under different penetration levels.

Telecommunication companies possess mobility information of their phone users, containing accurate locations and velocities of commuters travelling in public transportation system. Although the value of telecommunication data is well believed under the smart city vision, there is no existing solution to transform the data into actionable items for better transportation, mainly due to the lack of appropriate data utilization scheme and the limited processing capability on massive data. This paper presents the first ever system implementation of real-time public transportation crowd prediction based on telecommunication data, relying on the analytical power of advanced neural network models and the computation power of parallel streaming analytic engines. By analyzing the feeds of caller detail record (CDR) from mobile users in interested regions, our system is able to predict the number of metro passengers entering stations, the number of waiting passengers on the platforms and other important metrics on the crowd density. New techniques, including geographical-spatial data processing, weight-sharing recurrent neural network, and parallel streaming analytical programming, are employed in the system. These new techniques enable accurate and efficient prediction outputs, to meet the real-world business requirements from public transportation system.

Today, people can access various services with smart carry-on devices, e.g., surf the web with smart phones, make payments with credit cards, or ride a bus with commuting cards. In addition to the offered convenience, the access of such services can reveal their traveled trajectory to service providers. Very often, a user who has signed up for multiple services may expose her trajectory to more than one service providers. This state of affairs raises a privacy concern, but also an opportunity. On one hand, several colluding service providers, or a government agency that collects information from such service providers, may identify and reconstruct users' trajectories to an extent that can be threatening to personal privacy. On the other hand, the processing of such rich data may allow for the development of better services for the common good. In this paper, we take a neutral standpoint and investigate the potential for trajectories accumulated from different sources to be linked so as to reconstruct a larger trajectory of a single person. We develop a methodology, called fuzzy trajectory linking (FTL) that achieves this goal, and two instantiations thereof, one based on hypothesis testing and one on Naïve-Bayes. We provide a theoretical analysis for factors that affect FTL and use two real datasets to demonstrate that our algorithms effectively achieve their goals.

The tourism industry is a key economic driver for many cities. To understand tourists' traveling patterns can help both public and private relevant sectors design and improve their services to serve tourists better and get additional values from it. The existing approaches to discover tourists' traveling pattern focus on small sets of known tourists extracted from social media or other channels. The accuracy of the mining result cannot be guaranteed due to the small and bias set of samples.

Tourism industry has become a key economic driver for Singapore. Understanding the behaviors of tourists is very important for the government and private sectors, e.g., restaurants, hotels and advertising companies, to improve their existing services or create new business opportunities. In this joint work with Singapore's Land Transport Authority (LTA), we innovatively apply machine learning techniques to identity the tourists among public commuters using the public transportation data provided by LTA. On successful identification, the travelling patterns of tourists are then revealed and thus allow further analyses to be carried out such as on their favorite destinations, region of stay, etc. Technically, we model the tourists identification as a classification problem, and design an iterative learning algorithm to perform inference with limited prior knowledge and labeled data. We show the superiority of our algorithm with performance evaluation and comparison with other state-of-the-art learning algorithms. Further, we build an interactive web-based system for answering queries regarding the moving patterns of the tourists, which can be used by stakeholders to gain insight into tourists' travelling behaviors in Singapore.

Personal mobile data are being extensively collected by various service providers, in the form of data stream. Most service providers promise their customers for not misusing their data by paper-based agreement. However, the customers have no way to know whether the agreements are strictly followed or not, unless any scandals of private data misuse are revealed. To guarantee the correct use of customers' personal data and assure them of the service safety, system-level data privacy control between the data owners (i.e., Customers) and the data users (i.e., Service providers) is in compelling need. Inspired by the concept of Hippocratic data management, we design and implement a system, Hip Stream to systemically enforce different Hippocratic principles to preserve data providers' privacy when they send their data stream for services. In this paper, we describe the architecture of the Hip Stream system and demonstrate how it meets those privacy principles.

The Electronic Road Pricing (ERP) system was implemented by the Land Transport Authority of Singapore to control traffic by road pricing since 1998. To better understand the traffic condition and improve the pricing scheme, the government initiated the next generation ERP (ERP 2) project, which aims to use the Global Navigation Satellite System (GNSS) collecting positional data from vehicles for analysis. However, most drivers fear of being monitored once the government installs the devices in their vehicles to collect GPS data. The existing data stream management systems (DSMS) centralize both data management and privacy control at server site. This framework assumes DSMS server is secure and trustable, and protects providers' data from illegal access by data users. In ERP 2, the DSMS server is maintained by the government, i.e., data user. Thus, the existing framework is not adoptable. We propose a novel framework in which privacy protection is pushed to data provider site. By doing this, the system could be safer and more efficient. Our framework can be used for the situations such as ERP 2, i.e., data providers would like to control their own privacy policies and/or the workload of DSMS server needs to be reduced.

Path prediction is useful in a wide range of applications. Most of the existing solutions, however, are based on eager learning methods where models and patterns are extracted from historical trajectories and then used for future prediction. Since such approaches are committed to a set of statistically significant models or patterns, problems can arise in dynamic environments where the underlying models change quickly or where the regions are not covered with statistically significant models or patterns.

Path prediction is presently an important area of research with a wide range of applications. However, most of the existing path prediction solutions are based on eager learning methods which commit to a model or a set of patterns extracted from historical trajectories. Such methods do not perform very well in dynamic environments where the objects' trajectories are affected by many irregular factors which are not captured by pre-defined models or patterns. In this demonstration, we present the "R2-D2" system that supports probabilistic path prediction in dynamic environments. The core of our system is a "semi-lazy" learning approach to probabilistic path prediction which builds a prediction model on the fly using historical trajectories that are selected dynamically based on the trajectories of target objects. Our "R2-D2" system has a visual interface that shows how our path prediction algorithm works on several real-world datasets. It also allows us to experiment with various parameter settings.

We present a novel elastic system architecture called Plug Cloud, which aims to increase the power of low-compute (and possibly mobile) devices, such as tablets, through distributing high-compute tasks, such as rendering, data analysis and visualization, to a set of Plug Computers [1, 2] that can be added or removed from the system incrementally. These devices are connected through a wired/wireless connection and the network is formed seamlessly with zero configurations. Plug Cloud allows users of low-compute devices to acquire more processing power externally on demand by plugging one or more plug-computers as needed. Furthermore, it allows a user to remove the plug-computer safely at any time without bringing down the whole system. This makes an elastic network where it can expand and shrink automatically with one or more plug-computers being added or removed from the system. This innovative architecture forms a personal cloud infrastructure on demand to support users' computational needs. We have implemented a computer graphics rendering application using Plug Cloud architecture. We will demo our architecture and prototype system using a tablet and several plug-computers.

Big data management and analysis has become a hot topic in academic and industrial research. In fact, a large portion of big data in service today are initially streaming data. To preserve the privacy of such data that are collected from data streams, the most efficient way is to control the process of data collection according to corresponding privacy polices. In this paper, we design a framework to support data stream management with privacy-preserving capabilities. In particular, we focus on two premier principles of data privacy, limited disclosure and limited collection. With these two principles guaranteed, the archived data will not necessarily be checked for privacy protection, before analysis and other operations can be done.

We demonstrate a system that monitors the taxi availability at taxi stands by mining real-time taxi trajectory data streams. The system includes a server-side trajectory data stream processing and mining program and a client-side mobile application for Android smart phones. The server program continuously monitors for each taxi stand the numbers of taxis queueing at the taxi stand, the numbers of taxis that will pass the taxi stand, as well as the traffic conditions in the area around the stand. It delivers real time taxi and traffic information to mobile users via Restful web services. The client-side location-based mobile application consumes these services to help mobile users make informed transportation choices. For example the availability of taxis might yet be a deterrent when traffic is congested. Real world taxi trajectory data from more than 14000 taxis are used in the demo.

Matching two 3-D trajectories is an important task in a number of applications. The trajectory matching problem can be solved by aligning the two trajectories and taking the alignment score as their similarity measurement. In this paper, we propose a new method called "TrajAlign" (Trajectory Alignment). It aligns two trajectories by means of aligning their representative distance matrices. Experimental results show that our method is significantly more precise than the existing state-of-the-art methods. While the existing methods can provide correct answers in only up to 67% of the test cases, TrajAlign can offer correct results in 79% (i.e. 12% more) of the test cases, TrajAlign is also computationally inexpensive, and can be used practically for applications that demand efficiency.

One of the major objectives of Advanced Traffic Management Systems (ATMS) is to reduce traffic congestion in urban environments by improving the efficiency of utilization of existing infrastructures. Many creative and efficient technologies have been developed over the years. Although, commuters especially drivers take a critical part in containing traffic congestion problems, they are playing a passive role in the traffic-management ecosystem. Considerably, this is due to the information asymmetry between ATMS decision makers and commuters; what is missing is a matching mechanism to create a bridge between information providers and information consumers in a mobility environment. We solve this dilemma through implementing visual pertinent information services for commuters. We use probe vehicles to estimate the real-time traffic flow and disseminate this information effectively to users' mobile devices. We propose a 2-level indexing scheme to effectively index the grid cells which contain the spatial information. Processed information is disseminated to users through wireless means and presented in a user friendly interface on users' mobile devices. We have implemented a location-aware mobile application and back-end services. Experimental results show that our system is effective and scalable.

Mobile healthcare (m-Healthcare) systems are regarded as a solution to address skyrocketing healthcare costs without reducing the quality of patient care. It is our aim to build an m-Healthcare platform based on the service-oriented computing paradigm. We are developing a Service-oriented Architecture (SOA) for m-Healthcare services platform, called SOAMOH that shall also support interfacing with the HL7 standard and facilitate the provisioning of healthcare to people anywhere, anytime using mobile devices that are connected through wireless communication technologies.

We present the design and evaluation of PeerDB, a peer-to-peer (P2P) distributed data sharing system. PeerDB distinguishes itself from existing P2P systems in several ways. First, it is a full-fledge data management system that supports fine-grain content-based searching. Second, it facilitates sharing of data without shared schema. Third, it combines the power of mobile agents into P2P systems to perform operations at peers' sites. Fourth, PeerDB network is self-configurable, i.e., a node can dynamically optimize the set of peers that it can communicate directly with based on some optimization criterion. By keeping peers that provide most information or services in close proximity (i.e., direct communication), the network bandwidth can be better utilized and system performance can be optimized. We implemented and evaluated PeerDB on a cluster of 32 Pentium II PCs. Our experimental results show that PeerDB can effectively exploit P2P technologies for distributed data sharing.

No abstract available.

We present BestPeer, a prototype P2P system that we have implemented at the National University of Singapore. BestPeer is a generic P2P system designed to serve as a platform on which P2P applications can be developed easily and efficiently. The network consists of two types of entities: a large number of computers (nodes), and a relatively fewer number of location independent global name lookup (LIGLO) servers. Each participating node runs the BestPeer (Java-based) software and will be able to communicate or share resources with any other nodes (i.e., peers) in the BestPeer network. Each node comprises two types of data: private data and sharable data. Nodes can only access peers' data that are sharable.

Peer-to-Peer (P2P) systems are becoming increasingly popular as they enable users to exchange digital information by participating in complex networks. Such systems are inexpensive, easy to use, highly scalable and do not require central administration. Despite their advantages, however, limited work has been done on employing database systems on top of P2P networks.Here we propose the PeerOLAP architecture for supporting On-Line Analytical Processing queries. A large number low-end clients, each containing a cache with the most useful results, are connected through an arbitrary P2P network. If a query cannot be answered locally (i.e. by using the cache contents of the computer where it is issued), it is propagated through the network until a peer that has cached the answer is found. An answer may also be constructed by partial results from many peers. Thus PeerOLAP acts as a large distributed cache, which amplifies the benefits of traditional client-side caching. The system is fully distributed and can reconfigure itself on-the-fly in order to decrease the query cost for the observed workload. This paper describes the core components of PeerOLAP and presents our results both from simulation and a prototype installation running on geographically remote peers.

With the flurry of research on P2P computing, many P2P technical challenges have emerged, one of which is how to efficiently locate desired resources. Advances have been made in this hot research field, where the pioneers are Pastry, CAN, Chord, and Tapestry. By using the functionality of a distributed hash table, they have achieved fair effectiveness. However they have many common limitations, such as ignoring the autonomous nature of peers, and just supporting weakly semantic functions. According to reality in the distributed network, we propose a content-based location mechanism, which not only keeps the autonomy of peers, but also supports approximate query and finer granularity of content sharing. Furthermore, this mechanism also facilitates P2P system to evolve dynamically. We have also used PeerIS, a P2P based information system used to verify it and obtained satisfactory results.