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Increasingly, many security and privacy-sensitive applications are running on mobile platforms. However, as mobile operating systems are becoming increasingly sophisticated, they are vulnerable to various attacks. In addressing the need of running high assurance mobile apps in a secure environment even though the operating systems are untrusted, this paper presents vTrust, a new mobile app trusted execution environment, which offloads the general execution and storage of a mobile app to a trusted remote server (e.g., a VM running in a cloud) and secures the I/O between the server and the mobile device with the aid of a trusted hypervisor on the mobile device. Specifically, vTrust establishes an encrypted I/O channel between the local hypervisor and the remote server. In this way, any sensitive data flowing through the mobile OS, which the hypervisor hosts, is encrypted from the perspective of the local mobile OS. To enhance the performance of vTrust, we have also designed multiple optimizations, such as output data compression and selective sensor data transmission. We have implemented vTrust, and our evaluation shows that it has limited impact on both user experience and the application performance. [ABSTRACT FROM AUTHOR]

Mobile crowdsensing (MCS) has attained much attention for gathering distributed mobile users to complete large-scale sensing tasks. To ensure the task completion, enough users should be motivated to participate in sensing tasks. Thus, much research in MCS focuses on proposing incentive mechanism, and these works usually focus on the offline scenario, where the information of all users is available to the platform. However, we argue that the actual MCS is usually an online scenario, where the platform does not know the user's information until they establish connections with the platform. Meanwhile, mobile users connect to the platform randomly and will cut off the connection at any time. Hence, when accessed by a user, the platform needs to make an irrevocable decision instantly about whether to select the user or not, and decides a remuneration for the user without knowing future information. In this paper, we first propose a reverse-auction framework to model the interaction between the platform and mobile users. Then, we present an online truthful incentive mechanism (OTIM) to motivate users, including online winner selection and remuneration determination strategies. Finally, massive simulations are conducted based on three real traces, and the simulation results illustrate that OTIM achieves truthfulness, individual rationality, computational efficiency and an approximately full budget utilization. [ABSTRACT FROM AUTHOR]

Modern mobile operating systems support displaying Web pages in native mobile applications. When an app user navigates to a specific location containing a Web page, the Web page will be loaded and rendered from within the app. Such kind of Web browsing, as we call embedded Web browsing, is different from traditional Web browsing, which involves typing a URL on a browser and loading the Web page. However, little has been known about the prevalence or performance of such embedded Web pages. In this paper, we conduct, to the best of our knowledge, the first measurement study on embedded Web browsing on Android. Our study on 22,521 popular Android apps shows that 57.9 and 73.8 percent of apps embed Web pages on two popular app markets, that is, Google Play and Wandoujia, respectively. We design and implement EWProfiler, a tool that can automatically search for embedded Web pages inside apps, trigger page loads, and retrieve performance metrics to analyze the embedded Web browsing performance at scale. Based on 445 embedded Web pages obtained by EWProfiler in 99 popular apps from the two app markets, we investigate the characteristics and performance of embedded Web pages, and find that embedded Web pages significantly impede the app user experience. We investigate the effectiveness of three techniques, i.e., separating the browser kernel to a different process, loading pages from the local storage, and pre-rendering, to optimize the performance of embedded Web browsing. We believe that our findings could draw the attention of Web developers, browser vendors, app developers, and mobile OS vendors together toward a better performance of embedded Web browsing. [ABSTRACT FROM AUTHOR]

With the increasing applications of wheeled mobile manipulators (WMMs), consisting of a mobile platform (MP) and a manipulator, in diverse fields, new challenges have arisen in achieving multiple tasks such as obstacle avoidance in a constrained environment during the end-effector (EE) operation. A WMM is usually redundant due to the combination of the MP and the manipulator, making multitask control possible via employing its null space. Dual-user/two-handed teleoperation of a WMM is desirable for tasks where it is important to simultaneously control the poses of both the MP and the EE. The existing teleoperation approaches for WMMs are mostly executed at the kinematic level, without considering the nonlinear rigid-body dynamics of the WMMs. In this article, a task-priority-based dual-user teleoperation framework for a WMM is implemented to perform tasks in a constrained environment. It can simultaneously manipulate the MP and the EE, the overground obstacles are avoided by telecontrolling the MP using the WMM’s null space. Any residual redundancy can be further employed for other tasks such as singularity avoidance. The stability of the entire teleoperation design is rigorously proved even with arbitrary time delays. Experiments with a dual-user teleoperation system, consisting of two local robots and an omnidirectional WMM, are conducted to verify the proposed approach’s feasibility and effectiveness. [ABSTRACT FROM AUTHOR]

In mobile crowdsourcing, platforms seek to incentivize heterogeneous workers to complete tasks (e.g., road traffic sensing) and truthfully report their solutions. When platforms cannot verify the quality of the workers’ solutions, the crowdsourcing problem is known as information elicitation without verification (IEWV). In an IEWV problem, a platform needs to provide incentives to motivate high-quality solutions and truthful reporting of the solutions from the workers. A common approach to solve the IEWV problem is majority voting, where each worker is rewarded according to whether his solution matches the majority’s solution. However, previous work has not considered workers with heterogeneous solution accuracy. This is unrealistic in many domains, where one would expect workers to differ in judgment, expertise, and reliability. Moreover, prior work has not considered how this heterogeneity affects a platform’s tradeoff between the quality of the workers’ solutions and the platform’s cost of achieving this. We address these gaps by studying the interactions between the mobile crowdsourcing platform and workers as a two-stage Stackelberg game. In Stage I, the platform chooses the reward level for majority voting. In Stage II, the workers decide their effort levels and reporting strategies. We show that as a worker’s solution accuracy increases, he is more likely, in equilibrium, to exert effort and truthfully report his solution. However, given a fixed total worker population, surprisingly, the platform’s payoff may decrease in the number of high-accuracy workers. We further characterize the value of knowing the workers’ solution accuracy in terms of improving the platform’s optimal reward design and maximizing its payoff. Knowing such information enables a more effective aggregation of the workers’ solutions. We further design a discriminatory reward policy to incentivize heterogeneous workers. Surprisingly, such a discriminatory policy can improve both the platform’s and the workers’ payoffs, and hence improve the social welfare. [ABSTRACT FROM AUTHOR]

We constructed an open multi-access network platform using open source hardware and software. The open multi-access network platform is characterized by flexible utilization of network functions, integral management and control of wired and wireless access networks, zero-touch provisioning, intelligent resource monitoring, and dynamic task offloading. We also propose application-driven dynamic task offloading that utilizes intelligent resource monitoring to ensure effective task processing in edge and cloud servers. For this purpose, we developed a mobile application and server applications for the open multi-access network platform. To investigate the feasibility and availability of our developed platform, we experimentally and analytically evaluated the effectiveness of application-driven dynamic task offloading and intelligent resource monitoring. The experimental results demonstrate that application-driven dynamic task offloading could reduce real-time task response time and traffic over metro and core networks. [ABSTRACT FROM AUTHOR]

With the development of multimedia technology, Augmented Reality (AR) has become a promising next-generation mobile platform. The primary value of AR is to promote the fusion of digital contents and real-world environments, however, studies on how this fusion will influence the Quality of Experience (QoE) of these two components are lacking. To achieve better QoE of AR, whose two layers are influenced by each other, it is important to evaluate its perceptual quality first. In this paper, we consider AR technology as the superimposition of virtual scenes and real scenes, and introduce visual confusion as its basic theory. A more general problem is first proposed, which is evaluating the perceptual quality of superimposed images, i.e., confusing image quality assessment. A ConFusing Image Quality Assessment (CFIQA) database is established, which includes 600 reference images and 300 distorted images generated by mixing reference images in pairs. Then a subjective quality perception experiment is conducted towards attaining a better understanding of how humans perceive the confusing images. Based on the CFIQA database, several benchmark models and a specifically designed CFIQA model are proposed for solving this problem. Experimental results show that the proposed CFIQA model achieves state-of-the-art performance compared to other benchmark models. Moreover, an extended ARIQA study is further conducted based on the CFIQA study. We establish an ARIQA database to better simulate the real AR application scenarios, which contains 20 AR reference images, 20 background (BG) reference images, and 560 distorted images generated from AR and BG references, as well as the correspondingly collected subjective quality ratings. Three types of full-reference (FR) IQA benchmark variants are designed to study whether we should consider the visual confusion when designing corresponding IQA algorithms. An ARIQA metric is finally proposed for better evaluating the perceptual quality of AR images. Experimental results demonstrate the good generalization ability of the CFIQA model and the state-of-the-art performance of the ARIQA model. The databases, benchmark models, and proposed metrics are available at: https://github.com/DuanHuiyu/ARIQA. [ABSTRACT FROM AUTHOR]

Gait impairment represented by crouch gait is the main cause of decreases in the quality of lives of children with cerebral palsy. Various robotic rehabilitation interventions have been used to improve gait abnormalities in the sagittal plane of children with cerebral palsy, such as excessive flexion in the hip and knee joints, yet in few studies have postural improvements in the coronal plane been observed. The aim of this study was to design and validate a gait rehabilitation system using a new cable-driven mechanism applying assist in the coronal plane. We developed a mobile cable-tensioning platform that can control the magnitude and direction of the tension vector applied at the knee joints during treadmill walking, while minimizing the inertia of the worn part of the device for less obstructing the natural movement of the lower limbs. To validate the effectiveness of the proposed system, three different treadmill walking conditions were performed by four children with cerebral palsy. The experimental results showed that the system reduced hip adduction angle by an average of $4.57~\pm ~1.79^{\circ }$ compared to unassisted walking. Importantly, we also observed improvements of hip joint kinematics in the sagittal plane, indicating that crouch gait can be improved by postural correction in the coronal plane. The device also improved anterior and lateral pelvic tilts during treadmill walking. The proposed cable-tensioning platform can be used as a rehabilitation system for crouch gait, and more specifically, for correcting gait posture with minimal disturbance to the voluntary movement. [ABSTRACT FROM AUTHOR]

Fine-grained city-scale outdoor air pollution maps provide important environmental information for both city managers and residents. Installing portable sensors on vehicles (e.g., taxis, Ubers) provides a low-cost, easy-maintenance, and high-coverage approach to collecting data for air pollution estimation. However, as non-dedicated platforms, vehicles like taxis usually prefer gathering at busy areas of a city where it is more likely to pick up riders. This leaves many parts of the city unsensed or less-sensed. In addition, due to the natural changes in a city and the movements of the vehicles, the sensed and unsensed areas change over time. Consequently, challenges of air pollution estimation with data collected by non-dedicated mobile platforms are twofold: i. data coverage is sparse; ii. data coverage changes over time. Therefore, the major research question is: how can we derive accurate and robust fine-grained field (e.g., air pollution) estimation given dynamic and sparse data collected from uncontrollable mobile sensing platforms? This paper presents adaptive HMSS, an adaptive hybrid model-enabled sensing system for fine-grained air pollution estimation with dynamic and sparse data collected from uncontrollable mobile sensing platforms, which is achieved by combining the advantages of a physics guided model and a data driven model. To address the challenge of sparse coverage, the physical understanding of the spatiotemporal correlation for air pollution distribution in the physics guided model is utilized to infer values at unsensed sparse areas. Meanwhile, the data driven model is adopted to estimate the air pollution influential factors (e.g., buildings) not included in the physics guided model. To address the challenge of time-varying coverage, an adaptive model combination algorithm is designed to enable the system bias to either of the two models according to the amount of data collection and uncertainty of the model. To evaluate the system performance, we deployed 47 air pollution sensing devices on taxis and fixed locations in 2 cities for both controlled and uncontrolled experiments for over two weeks. The results show that with a resolution of $500 \;\mathrm m$ 500 m by $500\;\mathrm m$ 500 m by $1\;\mathrm {hour}$ 1 hour , our system achieves up to $3.2\times$ 3. 2 × error reduction when compared to the baseline approaches. [ABSTRACT FROM AUTHOR]

Mobile crowdsourcing platforms often want to incentivize workers to finish tasks with high quality and truthfully report their solutions by providing proper rewards. Most existing incentive mechanisms reward workers based on the comparison among workers’ reported solutions. However, these mechanisms are vulnerable to worker collusion, i.e., workers coordinate to misreport their solutions. We address such an issue by proposing a novel rewarding mechanism based on a ${truth detection}$ t r u t h d e t e c t i o n technology, which relies on the independent verification of the correctness of each worker’s response to some question with an imperfect accuracy. We model the interactions between the platform and workers as a two-stage Stackelberg game. In Stage I, the platform optimizes the reward mechanism parameters associated with truth detection to maximize its payoff. In Stage II, the workers decide their effort levels and reporting strategies to maximize their payoffs (which depend on the output of the truth detector). We analyze the game’s equilibrium and show that our proposed mechanism can effectively mitigate worker collusion. We also propose a novel rule, named filtered majority, for the platform to more effectively aggregate the workers’ solutions. Our proposed aggregation rule utilizes truth detection and outperforms the conventional simple majority rule. We further characterize the impact of the truth detection accuracy on the platform’s decisions. Surprisingly, under the simple majority rule, we show that as the truth detection accuracy improves, the platform should always incentivize more workers to exert effort and truthfully report. However, under our proposed filtered majority rule, we show that as the truth detection accuracy improves, in some cases, the platform should incentivize fewer workers and save costs. We further examine the impact of the workers’ imperfect estimation of the truth detection accuracy on the platform’s decisions. [ABSTRACT FROM AUTHOR]

Unmanned aerial vehicles (UAVs) and Terahertz (THz) technology are envisioned to play paramount roles in next-generation wireless communications. In this paper, we present a novel secure UAV-assisted mobile relaying system operating at THz bands for data acquisition from multiple ground user equipments (UEs) towards a destination. We assume that the UAV-mounted relay may act, besides providing relaying services, as a potential eavesdropper called the untrusted UAV-relay (UUR). To safeguard end-to-end communications, we present a secure two-phase transmission strategy with cooperative jamming. Then, we devise an optimization framework in terms of a new measure $-$ secrecy energy efficiency (SEE), defined as the ratio of achievable average secrecy rate to average system power consumption, which enables us to obtain the best possible security level while taking UUR’s inherent flight power limitation into account. For the sake of quality of service fairness amongst all the UEs, we aim to maximize the minimum SEE (MSEE) performance via the joint design of key system parameters, including UUR’s trajectory and velocity, communication scheduling, and network power allocation. Since the formulated problem is a mixed-integer nonconvex optimization and computationally intractable, we decouple it into four subproblems and propose alternative algorithms to solve it efficiently via greedy/sequential block successive convex approximation and non-linear fractional programming techniques. Numerical results demonstrate significant MSEE performance improvement of our designs compared to other known benchmarks. [ABSTRACT FROM AUTHOR]

The ultra-high-definition 16K Virtual Reality (VR) video is coming to ages with more ”real” virtual experience and less cybersickness. However, the huge bitrate and decoding overhead would overwhelm today’s network and mobile hardware. The widely-known Field-of-View (FoV) adaptation streaming method still has severe bitrate wastes and decoding overhead as it delivers FoV areas with grid-like static tiles. Inspired by this, we present a novel ShiftTile-traCking (STC) streaming scheme, which crops and delivers tiles by tracking FoV movement. It is equivalent to deliver an FoV planar video instead of VR videos. This would save huge bit-rate and reduce decoding complexity. We mainly entail three contributions. 1) To reduce projection distortions, a novel FoV-centric sphere projection is proposed, which projects VR videos with the center of users’ FoVs. 2) To cover diverse FoV movement trajectories with a limited number of tiles, we propose an optimal tiling algorithm by trajectory clustering. 3) To be resilient to FoV prediction errors, we propose an accuracy-sensitive streaming algorithm, which scales FoV areas by the prediction accuracy. The evaluation shows that under the same network conditions, STC improves up to 1.3dB V-PSNR, reduces up to 13.2% buffering ratio, and achieves 60% faster decoding speed (61.5 frames per second) compared with state-of-the-art solutions. [ABSTRACT FROM AUTHOR]

Many mobile applications deliver and show sensitive and private textual content to users including messages, social network posts, account information, and verification codes. All such textual content must be displayed to users but must be strongly protected from unauthorized access in mobile devices. Unfortunately, this is not the case in mobile devices today: malware that can compromise the OS can easily access textual content of other applications. We present SchrodinText, a system solution for strongly protecting the confidentiality of an application's selected UI textual content from a fully compromised OS. SchrodinText leverages a novel security monitor based on two hardware features on ARM processors: virtualization hardware and TrustZone. Our key contribution is a set of novel techniques that allow the OS to perform text rendering without needing access to the text itself, hence minimizing the trusted computing base (TCB). These techniques, collectively called oblivious rendering, enable the OS to rasterize and lay out all the characters without access to the text; the monitor resolves the right character glyphs onto the framebuffer observed by the user and protects them from the OS. Using our prototypes, we show that SchrodinText incurs noticeable overhead but that its performance is usable. [ABSTRACT FROM AUTHOR]

In participatory mobile crowdsensing (MCS) users repeatedly make choices among a finite set of alternatives, i.e., whether to contribute to a task or not and which task to contribute to. The platform coordinating the MCS campaigns often engineers these choices by selecting MCS tasks to recommend to users and offering monetary or in-kind rewards to motivate their contributions to them. In this paper, we revisit the well-investigated question of how to optimize the contributions of mobile end users to MCS tasks. However, we depart from the bulk of related literature by explicitly accounting for the bounded rationality evidenced in human decision making. Bounded rationality is a consequence of cognitive and other kinds of constraints, e.g., time pressure, and has been studied extensively in behavioral science. We first draw on work in the field of cognitive psychology to model the way boundedly rational users respond to MCS task offers as Fast-and-Frugal-Trees (FFTs). With each MCS task modeled as a vector of feature values, the decision process in FFTs proceeds through sequentially parsing lexicographically ordered features, resulting in choices that are satisfying but not necessarily optimal. We then formulate, analyze and solve the novel optimization problems that emerge for both nonprofit and for-profit MCS platforms in this context. The evaluation of our optimization approach highlights significant gains in both platform revenue and quality of task contributions when compared to heuristic rules that do not account for the lexicographic structure in human decision making. We show how this modeling framework readily extends to platforms that present multiple task offers to the users. Finally, we discuss how these models can be trained, iterate on their assumptions, and point to their implications for applications beyond MCS, where end-users make choices through the mediation of mobile/online platforms. [ABSTRACT FROM AUTHOR]

In this article, an energy-efficient deep learning processor is proposed for deep neural network (DNN) training in mobile platforms. Conventional mobile DNN training processors suffer from high-bit precision requirement and high ReLU-dependencies. The proposed processor breaks through these fundamental issues by adopting three new features. It first combines the runtime automatic bit precision searching method addition to both conventional dynamic fixed-point representation and stochastic rounding to realize low-precision training. It adopts bit-slice scalable core architecture with the input skipping functionality to exploit bit-slice-level fine-grained sparsity. The iterative channel reordering unit helps the processor to maintain high core utilization by solving the workload unbalancing problem during zero-slice skipping. It finally achieves at least 4.4× higher energy efficiency compared with the conventional DNN training processors. [ABSTRACT FROM AUTHOR]

With the rise of crowdsourcing and mobile crowdsensing techniques, a large number of crowdsourcing applications or platforms ($\mathbb {CAP}$ CAP ) have appeared. In the mean time, $\mathbb {CAP}$ CAP -related models and frameworks based on different research hypotheses are rapidly emerging, and they usually address specific issues from a certain perspective. Due to different settings and conditions, different models are not compatible with each other. However, $\mathbb {CAP}$ CAP urgently needs to combine these techniques to form a unified framework. In addition, these models needs to be learned and updated online with the extension of crowdsourced data and task types; thus, requiring a unified architecture that integrates lifelong learning concepts and breaks down the barriers between different modules. This paper draws on the idea of ubiquitous operating systems and proposes a novel OS (CrowdOS), which is an abstract software layer running between native OS and application layer. In particular, based on an in-depth analysis of the complex crowd environment and diverse characteristics of heterogeneous tasks, we construct the OS kernel and three core frameworks including task resolution and assignment framework (TRAF), integrated resource management (IRM), and task result quality optimization (TRO). In addition, we validate the usability of CrowdOS, module correctness and development efficiency. Our evaluation further reveals TRO brings enormous improvement in efficiency and a reduction in energy consumption. [ABSTRACT FROM AUTHOR]

Mobile manipulators are being deployed for transporting parts between machines and work stations in warehouses and shop floors. To increase the efficiency of operations, these mobile manipulators are required to complete the tasks as fast as possible. Picking up parts with the manipulator while the mobile base is moving decreases the time required to complete the transportation task and increases the efficiency of operations. However, motions of the manipulator on a moving platform can be risky, and hence, it is desired that the manipulator starts and ends its motions as close as possible to the part being picked up. In this article, we present a bidirectional sampling-based scheme for generating such manipulator trajectories for a given mobile base trajectory for pickup and transportation. Our approach implicitly determines the location of the mobile base where the manipulator motion starts and ends as well as where grasping happens. It also determines which grasping pose to use for picking up the part. Furthermore, we have presented the techniques to reduce the manipulator motion time (span time) and the computation time. Our approach enables us to reduce span time on average by 35% with a $16\times $ reduction in the computation time compared to the RRT-based baseline methods. Note to Practitioners—Transportation of objects is a crucial application in industrial and warehouse environments. Conveyor belts and AGVs are typically used for such applications as they provide an efficient mode of transportation of a large number of objects. However, they may not provide the flexibility which mobile manipulators bring in for small-scale operations. The method presented in this article provides a way to increase the efficiency of operation for mobile manipulators for transportation tasks. We attempt to reduce the risks of the manipulator colliding with expensive equipment and moving obstacles by making sure that the manipulator moves only when needed for picking up objects. Moreover, the method can be used to pick up and transport a variety of parts in different ways using a two-fingered gripper. The method can also easily incorporate different types of grippers and mobile platforms. [ABSTRACT FROM AUTHOR]

Mobile devices aggregate various types of data from sensitive corporate documents to personal content. While users desire to access this content on a single device via a unified user experience and through any mobile app, protecting this data is challenging. Even though different data types have different security and privacy needs, mobile operating systems include only a few, if any, functionalities for fine-grained data protection. We present SWIRLS, an Android-based mobile OS that provides a policy-based information-flow data protection abstraction for mobile apps to support BYOD (bring-your-own-device) use cases. SWIRLS attaches security policies to individual pieces of data and enforces these policies as the data flows through the device. Unlike current BYOD solutions like VMs that create duplication overload, SWIRLS provides a single environment to access content from different security contexts using the same applications while monitoring for malicious data leakage. SWIRLS leverages a two-level hybrid information flow tracking (IFT) mechanism to track both intra-application flows and a higher level IFT based on processes for application isolation. Our evaluation presents BYOD data protection use-cases such as limiting document sharing, preventing leakage based on document classification and security policies based on geo-fencing. SWIRLS only imposes a low battery consumption and performance overhead. [ABSTRACT FROM AUTHOR]

This article proposes a predictive end-effector control method for manipulators operating on mobile platforms subjected to unwanted base motion. Time series is used to forecast the base motion using historical state information. Then, a trajectory specified in the inertial frame is transformed to a predicted trajectory with respect to the manipulator. By tracking this transformed trajectory, the manipulator negates the base motion. A model-predictive control problem is formulated via quadratic programming (QP) to track said trajectory over the prediction horizon. Only the first control action in the control sequence is constrained by kinematic feasibility. In this manner, QP can be swiftly solved with linear inequality constraints. It is shown that the actual joint trajectory executed by the manipulator is always kinematically feasible. Moreover, tracking error can still be reduced despite future predicted control actions being infeasible. The method is validated through both simulation and experiment. The proposed method can reduce pose error by over 60% compared to a proportional–integral feedback controller. [ABSTRACT FROM AUTHOR]

Maintaining safe chip and device skin temperatures in small form-factor mobile devices (such as smartphones and tablets) while continuing to add new functionalities and provide higher performance has emerged as a key challenge. This article presents Therminator 2, an early stage, fast, full-device thermal analyzer, which generates accurate transient- and steady-state temperature maps of an entire smartphone starting from the application processor and other key device components, extending to the skin of the device itself. Therminator 2 uses advanced numerical optimization techniques to perform steady-state simulations 1.6 times faster than the prior art technique and is capable of performing transient-state simulations in real time and 1.25 times faster than the prior art method. The thermal analysis is sensitive to detailed device specifications (including its material composition and 3-D layout) as well as different use cases (each case specifying the set of active device components and their activity levels.) Therminator 2 considers all major components within the device, builds a corresponding compact thermal model for each component and the whole device, and produces their transient- and steady-state temperature maps. Temperature results obtained by using Therminator 2 have been validated against a commercial computational fluid dynamics (CFDs)-based tool, i.e., Autodesk Simulation CFD, and thermocouple measurements on a Qualcomm Mobile Developer Platform and Google Nexus 5. A case study on a Samsung Galaxy S4 using Therminator 2 is provided to relate the device performance to the skin temperature and investigate the thermal path design. [ABSTRACT FROM AUTHOR]

Recent breakthroughs in deep neural networks (DNNs) have fueled a tremendously growing demand for bringing DNN-powered intelligence into mobile platforms. While the potential of deploying DNNs on resource-constrained platforms has been demonstrated by DNN compression techniques, the current practice suffers from two limitations: 1) merely stand-alone compression schemes are investigated even though each compression technique only suit for certain types of DNN layers; and 2) mostly compression techniques are optimized for DNNs’ inference accuracy, without explicitly considering other application-driven system performance (e.g., latency and energy cost) and the varying resource availability across platforms (e.g., storage and processing capability). To this end, we propose AdaDeep, a usage-driven, automated DNN compression framework for systematically exploring the desired trade-off between performance and resource constraints, from a holistic system level. Specifically, in a layer-wise manner, AdaDeep automatically selects the most suitable combination of compression techniques and the corresponding compression hyperparameters for a given DNN. Thorough evaluations on six datasets and across twelve devices demonstrate that ${\sf AdaDeep}$ AdaDeep can achieve up to $18.6\times$ 18. 6 × latency reduction, $9.8\times$ 9. 8 × energy-efficiency improvement, and $37.3\times$ 37. 3 × storage reduction in DNNs while incurring negligible accuracy loss. Furthermore, ${\sf AdaDeep}$ AdaDeep also uncovers multiple novel combinations of compression techniques. [ABSTRACT FROM AUTHOR]

We present a novel online 3D scanning system for high-quality object reconstruction with a mobile device, called Mobile3DScanner. Using a mobile device equipped with an embedded RGBD camera, our system provides online 3D object reconstruction capability for users to acquire high-quality textured 3D object models. Starting with a simultaneous pose tracking and TSDF fusion module, our system allows users to scan an object with a mobile device to get a 3D model for real-time preview. After the real-time scanning process is completed, the scanned 3D model is globally optimized and mapped with multi-view textures as an efficient postprocess to get the final textured 3D model on the mobile device. Unlike most existing state-of-the-art systems which can only scan homeware objects such as toys with small dimensions due to the limited computation and memory resources of mobile platforms, our system can reconstruct objects with large dimensions such as statues. We propose a novel visual-inertial ICP approach to achieve real-time accurate 6DoF pose tracking of each incoming frame on the front end, while maintaining a keyframe pool on the back end where the keyframe poses are optimized by local BA. Simultaneously, the keyframe depth maps are fused by the optimized poses to a TSDF model in real-time. Especially, we propose a novel adaptive voxel resizing strategy to solve the out-of-memory problem of large dimension TSDF fusion on mobile platforms. In the post-process, the keyframe poses are globally optimized and the keyframe depth maps are optimized and fused to obtain a final object model with more accurate geometry. The experiments with quantitative and qualitative evaluation demonstrate the effectiveness of the proposed 3D scanning system based on a mobile device, which can successfully achieve online high-quality 3D reconstruction of natural objects with larger dimensions for efficient AR content creation. [ABSTRACT FROM AUTHOR]

This article addresses the problem of clutter cancelation for slowly moving target detection and localization in multichannel passive radar onboard mobile platforms. A post-Doppler space-time adaptive processing (STAP) approach is exploited in the case of an angle-dependent imbalance affecting the receiving channels. While the clutter suppression capability is ensured by the adaptivity of space-time filtering, different solutions are compared, aimed at recovering the detection performance losses associated with channel calibration errors. A space-time generalized-likelihood ratio test (GLRT) scheme is considered, where the steering vector is not specified in the spatial domain, resulting in a noncoherent integration of target echoes across the receiving channels. This is compared with a fully coherent GLRT scheme where echoes from the stationary scene are exploited for the proper calibration of spatial steering vector mismatch. The first scheme proves to be a simple solution for target detection in the passive radar case, offering comparable clutter cancelation capability. The second scheme, at the expense of an additional stage, offers slightly better detection performance and preserves target direction-of-arrival (DoA) estimation capability. Finally, the STAP scheme is employed for the maximum-likelihood estimation of target DoA, evaluating the role of the steering vector calibration against the negative impact of channel imbalance. The effectiveness of the proposed approaches is tested against both simulated and experimental data from a DVB-T-based mobile passive radar. [ABSTRACT FROM AUTHOR]

Recently, the state-of-the-art performance in various sensor based human activity recognition (HAR) tasks have been acquired by deep learning, which can extract automatically features from raw data. In order to obtain the best accuracy, many static layers have been always used to train deep neural networks, and their weight connectivity in network remains unchanged. Pursuing the best accuracy in mobile platforms with a very limited computational budget at millions of FLOPs is impractical. In this paper, we make use of shallow convolutional neural networks (CNNs) with channel-selectivity for the use of HAR. As we have known, it is for the first time to adopt channel-selectivity CNN for sensor based HAR tasks. We perform extensive experiments on 5 public benchmark HAR datasets consisting of UCI-HAR dataset, OPPORTUNITY dataset, UniMib-SHAR dataset, WISDM dataset, and PAMAP2 dataset. As a result, the channel-selectivity can achieve lower test errors than static layers. The existing performance of deep HAR can be further improved by the CNN with channel-selectivity without any extra cost. [ABSTRACT FROM AUTHOR]

Recent learned image coding has emerged with superior efficiency to conventional methods. It, however, is criticized for its complexity-exhaustive deep neural network (DNN) architectures, especially on resource-constrained mobile platforms. Thus we devise a two-stage approach: first, a range pre-processing is applied to constrain the dynamic range of feature map activation by leveraging its sparsity nature with densely clustered distribution, then a layer-wise range-adaptive quantization for convolutional parameter (e.g., weight, bias), and simple yet efficient linear scaling and range-dependent normalization for activation are executed, leading to a fully fixed-point inference architecture. All arithmetic operations and associated data tensors are processed using low-bit-width fixed-point numbers, yielding significant reductions of the computational complexity, memory space, and the elimination of platform-dependent inconsistency induced by floating-point operations. We first exemplify such fixed-point inference in a DNN-based image decoder, showing the comparable coding efficiency with its native floating-point model, against the same anchor using the High-Efficiency Video Coding (HEVC)-based intra image coder. We also extend proposed approach to the super-resolution network for learned resolution scaling-based video streaming, and VGG network-based classification tasks, both of which present negligible performance loss. These evidence the generalization of our approach for efficient DNN processing of various tasks. All materials are made publicly accessible at http://njuvision.github.io/fixed-point/. [ABSTRACT FROM AUTHOR]

Games have been one of the most popular applications on smartphones. In order to meet the increasing computational complexity of mobile games, smartphones are now equipped with heterogeneous CPU multi-core architectures like big.LITTLE as well as high-performance GPUs. However, the integrated CPUs and GPUs drain the battery quickly, which has become a bottleneck for improving user experience. In addition to traditional Dynamic Voltage and Frequency Scaling (DVFS) technique for CPUs and GPUs power reduction, heterogeneous multi-core processors, such as the big.LITTLE architecture, have been designed to offer more opportunity for performance-energy tradeoffs. But current processor governors in smartphones can not exploit these power-saving mechanisms wisely, causing considerable energy waste. In this article, we propose a CPU-GPU governing framework that recognizes the performance demand for different game scenes, and select the most energy-efficient hardware configuration for the corresponding scenes. We implement our framework on an ODROID-XU4 mobile platform, and the experiments show that our framework can achieve 26.7, 16.6, and 10.5 percent power saving on average without compromising user experience when compared to the default governor used in our platform and two governors proposed by other researchers, respectively. [ABSTRACT FROM AUTHOR]

Equipping mobile platforms with deep learning applications is very valuable. Providing healthcare services in remote areas, improving privacy, and lowering needed communication bandwidth are the advantages of such platforms. Designing an efficient computation engine enhances the performance of these platforms while running deep neural networks (DNNs). Energy-efficient DNN accelerators use skipping sparsity and early negative output feature detection to prune the computations. Spatial DNN accelerators in principle can support computation-pruning techniques compared to other common architectures, such as systolic arrays. These accelerators need a separate data distribution fabric like buses or trees with support for high bandwidth to run the mentioned techniques efficiently and avoid network on chip (NoC)-based stalls. Spatial designs suffer from divergence and unequal work distribution. Therefore, applying computation-pruning techniques into a spatial design, which is even equipped with an NoC that supports high bandwidth for the processing elements (PEs), still causes stalls inside the computation engine. In a spatial architecture, the PEs that perform their tasks earlier have a slack time compared to others. In this article, we propose an architecture with a negligible area overhead based on sharing the scratchpads in a novel way between the PEs to use the available slack time caused by applying computation-pruning techniques or the used NoC format. With the use of our dataflow, a spatial engine can benefit from computation-pruning and data reuse techniques more efficiently. When compared to the reference design, our proposed method achieves a speedup of $\times 1.24$ and an energy efficiency of $\times 1.18$ per inference. [ABSTRACT FROM AUTHOR]

Cable-driven parallel robots (CDPRs) are a new type of parallel robots with a mobile platform driven by several cables. The flexibility of the structure not only helps them perform better than traditional parallel robots, but also brings about the issues of model uncertainty and multicable coordination. To handle these problems, a novel adaptive synchronization control (ASC) scheme is proposed to suppress the uncertainties of kinematics and dynamics simultaneously, regulate the coordination motion of multiple cables, and finish high-precision tracking tasks. In the proposed scheme, apart from tracking error, a new synchronization error is introduced to describe the coordination motion relationship between adjacent cables. According to these defined errors, the kinematic and dynamic adaptation laws are designed through the linear expressions of kinematic and dynamic models, respectively. Finally, the ASC scheme is presented as well as a tension distribution algorithm. The tracking experiments are implemented on a redundantly actuated 3-degree-of-freedom CDPR with four cables. The proposed ASC scheme can effectively complete the correction of the model parameters by using the feedback of errors and enhance the tracking accuracy of each cable and the synchronization accuracy between all the cables significantly, thereby ultimately improving the control performance of the mobile platform. [ABSTRACT FROM AUTHOR]

Mobile video chatting has emerged as an important Internet multimedia application that greatly enriches interpersonal communications. Mobile power efficiency is crucial to the service quality and time of video chatting on battery-limited smartphones. However, the power characteristics of the video coding and data communication are highly complex due to the time-varying network conditions and dynamic mobile energy features. This incurs crucial challenges to maintaining the low power dissipation of mobile chatting application while streaming satisfactory-quality videos. To address these challenges, this paper presents a joinT cOding-tranSmission Optimization (TOSO) protocol at application layer that performs machine learning based adaptation of the video bit rate and FEC (Forward Error Correction) coding parameters. By taking advantage of analytical and empirical models characterizing the quality-power relationship, TOSO is able to maximize video quality subject to a specified upper bound of power consumption in mobile chat application. This distinguishing feature prevents the video chat from draining battery too quickly. Moreover, it allows the smartphone operating system or the mobile user to define a desired video chat duration given the remaining battery, avoiding unpleasant conversation disruption due to battery depletion. Extensive experiments based on the Linphone platform and Exata network emulator show that TOSO outperforms baseline approaches by 29.3 percent in power conservation while achieving the same video quality level. [ABSTRACT FROM AUTHOR]

Free space optics (FSO) is considered primarily for establishing point-to-point (PtP). However, due to the increasing demand for mobile platforms and mechanisms to establish point-to-multipoint (PtM) connections, this research proposes and implements a novel PtM tracking mechanism for FSO communication. The alignment mechanism consists of two tracking systems, i.e., coarse tracking and fine-tuning. The coarse tracking is responsible to locate FSO transceivers placed at different positions by using magnetometer sensors connected to the cloud. On the other hand, the fine-tuning mechanism overcomes high-frequency amplitude oscillation or jitter with a displacement range of 8 cm. The link is continuously monitored and if the link is lost or not established after a pre-determined time, then the reference line-of-sight (LoS) angle is updated in the cloud to provide an alternate connection. The stability of the closed-loop system is analyzed in terms of root locus and step response. The proposed PtM system is experimentally validated with FSO terminals located at different locations and distances over indoor and outdoor environments. The proposed method achieved an alignment time of less than 5 s for ten degrees of misalignment. [ABSTRACT FROM AUTHOR]

Heterogeneous robot teams offer significant advantages for exploration and navigation missions in unknown environments. Notably, the air–ground robot teams have superior efficiency due to their mixed abilities and shared sensor resources useful when completing missions. However, the high energy consumption and reduced payload capability of the vertical take-off and landing (VTOL) aerial platforms limit the complete robot team’s behavior. At some point in a mission, the aircraft needs to return to the base, land, and replenish its batteries. This task restricts the team to explore the environment in-depth and to work for longer durations. To solve this problem, we present an autonomous system for docking a VTOL-unmanned aerial vehicles (UAVs) with a mobile manipulator. The central measurement-actuation unit consists of a robot manipulator mounted on a mobile platform with a visual sensor configured as an eye-in-hand device. The visual information is used to execute a stable UAV tracking to achieve air–ground robot contact firmly. This strategy allows the multirobot team to economize and potentially recover aircraft energy. It also enables the robust ground platform to protect and store the aircraft facilitating to continue the mission for a longer duration. The on-site autonomous docking can be initiated multiple times, allowing the team to explore larger areas and complete long-term missions. The proposed method has been tested in simulations and real environments with detailed experimental results. [ABSTRACT FROM AUTHOR]

In this study, a real-time underwater onboard vision sensing system is developed for robotic gripping. First, an efficient image enhancement method based on the Retinex theory is presented. The enhanced images are provided for underwater robot to observe the seabed environment clearly via cameras. Subsequently, a real-time lightweight object detector (RLOD) for the mobile embedded platform is proposed. The RLOD is designed as an hourglass detector network, which introduces dense connections and a featured pyramid network to improve the detection performance and speed. Moreover, from an engineering perspective, two merging methods are used to deploy the trained network. It can be implemented at 11.11 frames per second (FPS) on the Nvidia Jetson TX2 processor, satisfying the real-time requirement of underwater robotic gripping. Furthermore, a refraction tracing model is constructed. The comparative results show the effectiveness of the proposed methods. Finally, this onboard vision sensing system is mounted on an underwater robot with a manipulator to implement robotic gripping. Pool and sea experiments are conducted to verify the practicability of the developed system. [ABSTRACT FROM AUTHOR]

The pervasive penetration of mobile smart devices has significantly enriched Internet applications and undoubtedly reshaped the way that users access Internet services. Different from traditional desktop applications, mobile Internet applications require users to input via touch screens and view outputs on the displays with considerably limited size. The significant conflict between the limited-size of touch screens and the richness of online media contents widely exists in dynamic-viewport mobile applications, a class of mobile Internet applications that download contents beyond the user's viewing region (referred to as viewport). As dynamic-viewport mobile applications usually use HTTP for content downloading, to improve their quality of experience (QoE) and cost efficiency, in this paper, we present a Mobile-Friendly HTTP middleware (MF-HTTP), which can interpret user touch screen inputs and optimize the HTTP downloading of media objects for such applications. We first demystify screen scrolling in mobile operating systems and precisely break down the viewport moving process. We identify the key influential factors for media object downloading and develop an optimal download scheme. Towards building a practical middleware, we further discuss and address the implementation issues in detail. We implement a MF-HTTP prototype based on Android platforms and evaluate the performance of MF-HTTP by conducting concrete case studies on two representative dynamic-viewport mobile applications, namely, web browsing and 360-degree video streaming. [ABSTRACT FROM AUTHOR]

The reliability of mobile devices is a challenge for vendors, since the mobile software stack has significantly grown in complexity. In this article, we study how to assess the impact of faults on the quality of user experience in the Android mobile OS through fault injection. We first address the problem of identifying a realistic fault model for the Android OS, by providing to developers a set of lightweight and systematic guidelines for fault modeling. Then, we present an extensible fault injection tool (AndroFIT) to apply such fault model on actual, commercial Android devices. Finally, we present a large fault injection experimentation on three Android products from major vendors, and point out several reliability issues and opportunities for improving the Android OS. [ABSTRACT FROM AUTHOR]

Air quality, especially particulate matter, has recently attracted a lot of attention from governments, industry, and academia, motivating the use of denser air quality monitoring networks based on low-cost sensing strategies. However, low-cost sensors are frequently sensitive to aging, environmental conditions, and pollutant cross-sensitivities. These issues have been only partially addressed, limiting their usage. In this study, we develop a low-cost particulate matter monitoring system based on special-purpose acquisition boards, deployed for monitoring air quality on both stationary and mobile sensor platforms. We explore the influence of all model variables, the quality of different calibration strategies, the accuracy across different concentration ranges, and the usefulness of redundant sensors placed in each station. The collected sensor data amounts to about 50GB of data, gathered in six months during the winter season. Tests of statically immovable stations include an analysis of accuracy and sensors’ reliability made by comparing our results with more accurate and expensive standard $\beta$ -radiation sensors. Tests on mobile stations have been designed to analyze the reactivity of our system to unexpected and abrupt events. These experiments embrace traffic analysis, pollution investigation using different means of transport and pollution analysis during peculiar events. With respect to other approaches, our methodology has been proved to be extremely easy to calibrate, to offer a very high sample rate (one sample per second), and to be based on an open-source software architecture. Database and software are available as open source in . [ABSTRACT FROM AUTHOR]

Convolutional neural networks (CNNs) have become powerful algorithms in various tasks. Application-specific integrated circuit (ASIC) has been widely used to accelerate CNN on mobile platforms because of its tremendous energy efficiency and performance. Meanwhile, CNNs have become much sparser with the development of network pruning algorithms. Recent works have employed different methods to improve the energy efficiency and performance of ASIC accelerators by utilizing the sparsity character of CNN. However, some of these methods suffer from tremendous output memory overhead and performance degradation induced by hash collisions. To overcome the aforementioned problem, we propose GAAS: an efficient group associated architecture and scheduler module for sparse CNN accelerators. It achieves smaller output memory overhead and higher performance compared with the state-of-the-art accelerator. Our proposed method GAAS mainly consists of two parts: 1) an $n$ -way group associated architecture to reduce the output memory overhead and 2) a scheduler module to improve the performance. Besides, a load-balancing algorithm is proposed and implemented in the scheduler module to improve the performance by reducing the hash collision rate. To demonstrate the efficiency of GAAS, we implement a 4-way image-principal associated architecture with a $16\times 16$ PE array and the scheduler module on our proposed method. The experimental results on AlexNet, VGG16, ResNet18, and MobileNet show that GAAS can reduce the output memory overhead by 50%, and it can surely improve the performance of them by $1.53\times $ , $1.62\times $ , $1.46\times $ , and $1.55\times $ , respectively. [ABSTRACT FROM AUTHOR]

Recent diversification of mobile computing devices allows a mobile user to own multiple types of devices for different application scenarios, but also results in various restrictions on the performance and usability of these devices. A viable solution to such restriction is to incorporate and interconnect mobile devices towards a personal mobile cloud where these devices can complement each other via cooperative resource sharing, but is challenging due to the heterogeneity of mobile devices in both hardware and software aspects. In this paper, we propose a novel design of resource sharing framework to address these challenges and generically interconnect heterogeneous mobile devices. Our basic idea is to mask the hardware and software heterogeneity in mobile systems by exploiting the existing mobile OS services as the interface of resource sharing, and further develop the resource sharing framework as a middleware in the mobile OS. We have implemented our design over various mobile platforms with diverse characteristics and resource limits, and demonstrated that our design can efficiently support generic resource sharing among heterogeneous mobile devices without incurring significant system overhead or requiring individual system modification. [ABSTRACT FROM AUTHOR]

We present a real-time monocular 3D reconstruction system on a mobile phone, called Mobile3DRecon. Using an embedded monocular camera, our system provides an online mesh generation capability on back end together with real-time 6DoF pose tracking on front end for users to achieve realistic AR effects and interactions on mobile phones. Unlike most existing state-of-the-art systems which produce only point cloud based 3D models online or surface mesh offline, we propose a novel online incremental mesh generation approach to achieve fast online dense surface mesh reconstruction to satisfy the demand of real-time AR applications. For each keyframe of 6DoF tracking, we perform a robust monocular depth estimation, with a multi-view semi-global matching method followed by a depth refinement post-processing. The proposed mesh generation module incrementally fuses each estimated keyframe depth map to an online dense surface mesh, which is useful for achieving realistic AR effects such as occlusions and collisions. We verify our real-time reconstruction results on two mid-range mobile platforms. The experiments with quantitative and qualitative evaluation demonstrate the effectiveness of the proposed monocular 3D reconstruction system, which can handle the occlusions and collisions between virtual objects and real scenes to achieve realistic AR effects. [ABSTRACT FROM AUTHOR]

As digital currency wallets are gaining popularity, security incidents related to them are also increasing. They lead to the disclosure of users' private information and security threats of users' assets. This article analyzes the security risks of digital wallets in Android, which is the most popular mobile operating system. it first establishes the threat model and the security goals, and then analyzes the attack surface and attack vectors from the aspects of wallet apps and the Android system. Experiments are conducted on two realworld digital currency wallet apps, and the results reveal several serious security risks in these apps, which highlight the necessity and importance of developing secure cryptocurrency wallets. [ABSTRACT FROM AUTHOR]

The distribution of indoor illuminance affects the health and the performance of humans and is, therefore, subject to audits. Audits are performed after each modification of the light sources, and the currently adopted approach uses a human operator to perform measurements manually. This process is time-consuming, and we, therefore, aim to automate it with a mobile platform. In order to automate the process, we propose an online algorithm for selecting the control points. The algorithm is iterative, and it takes previous measurements into account in order to select the control points adaptively. We show how the proposed method can be combined with a mobile platform to perform the audit autonomously. Initially, the mobile platform, equipped with a laser range finder, is used to build the floor plan of the room. This floor plan is then used to restrict the area within which the control points can be selected. The whole measurement process is then executed without the presence or the intervention of a human operator, and this reduces the time needed for the audit. We have performed simulated and real experiments to demonstrate the performance of the proposed approach. [ABSTRACT FROM AUTHOR]

This article describes the development of a software architectural framework for implementing compute-aware control systems, where the term “compute-aware” describes controllers that can modify existing low-level computing platform power managers in response to the needs of the physical system controller. This level of interaction means that high-level decisions can be made as to when to operate the computing platform in a power-savings mode or a high-performance mode in response to situation awareness of the physical system. The framework is demonstrated experimentally on a mobile robot platform. In this example, a situation-aware governor is developed that adjusts the speed of the processor based on the physical performance of the robot as it traverses a path through obstacles. The results show that the situation-aware governor results in overall power savings of up to 38.9 percent with 1.3 percent degradation in performance compared to the static high-power strategy. [ABSTRACT FROM AUTHOR]

Small-scale ocean observations play an important role in oceanographic research. The station-keeping method based on the underwater mobile platform has been proposed as a means of small-scale ocean observation with the advantages of low cost and high flexibility. However, few studies have carried out complete modeling of the small-scale ocean observation process of mobile platforms and proposed a corresponding station-keeping method based on this. In this article, a hybrid underwater profiler (HUP) was tested under two working conditions for its ability of maintaining position during designated area persistent monitoring (DAPM) within a specific area of the sea over a long period. The DAPM problem is modeled and the cost function that evaluates the performance of DAPM is defined. If the underwater profiler cannot measure data about underwater currents, it can maintain its position by setting constant gliding and yaw angles based on the depth-averaged current measured each time it surfaces. If it has instruments to observe ocean currents at each depth during a dive, the profiler can maintain its position using a strategy based on a quasi-Newton method. Simulation results show that the gliding strategies effectively assist the HUP in monitoring a designated area. Additionally, sea trials were performed without instrumentation to measure ocean currents and the effectiveness of the simpler gliding strategy was clearly demonstrated. [ABSTRACT FROM AUTHOR]

Data processing on convolutional neural networks (CNNs) places a heavy burden on energy-constrained mobile platforms. This article optimizes energy on a mobile client by partitioning CNN computations between in situ processing on the client and offloaded computations in the cloud. A new analytical CNN energy model is formulated, capturing all major components of the in situ computation, for ASIC-based deep learning accelerators. The model is benchmarked against measured silicon data. The analytical framework is used to determine the optimal energy partition point between the client and the cloud at runtime. On standard CNN topologies, partitioned computation is demonstrated to provide significant energy savings on the client over a fully cloud-based computation or fully in situ computation. For example, at 80 Mbps effective bit rate and 0.78 W transmission power, the optimal partition for AlexNet [SqueezeNet] saves up to 52.4% [73.4%] energy over a fully cloud-based computation and 27.3% [28.8%] energy over a fully in situ computation. [ABSTRACT FROM AUTHOR]

Correlation filters (CF) have received considerable attention in visual tracking because of their computational efficiency. Leveraging deep features via off-the-shelf CNN models (e.g., VGG), CF trackers achieve state-of-the-art performance while consuming a large number of computing resources. This limits deep CF trackers to be deployed to many mobile platforms on which only a single-core CPU is available. In this paper, we propose to jointly compress and transfer off-the-shelf CNN models within a knowledge distillation framework. We formulate a CNN model pretrained from the image classification task as a teacher network, and distill this teacher network into a lightweight student network as the feature extractor to speed up CF trackers. In the distillation process, we propose a fidelity loss to enable the student network to maintain the representation capability of the teacher network. Meanwhile, we design a tracking loss to adapt the objective of the student network from object recognition to visual tracking. The distillation process is performed offline on multiple layers and adaptively updates the student network using a background-aware online learning scheme. The online adaptation stage exploits the background contents to improve the feature discrimination of the student network. Extensive experiments on six standard datasets demonstrate that the lightweight student network accelerates the speed of state-of-the-art deep CF trackers to real-time on a single-core CPU while maintaining almost the same tracking accuracy. [ABSTRACT FROM AUTHOR]

In this paper, we present a novel look-ahead concept for combined longitudinal and lateral vehicle following control for a car-like platoon. A nonlinear controller structure, which is based on Cooperative Adaptive Cruise Control, is designed for the lateral and longitudinal direction. For practical implementation and cost efficiency, a preceding vehicle look-ahead approach is considered since it utilizes the already available information (such as preceding vehicle position, orientation, and velocity) from radar and vehicle-to-vehicle communication. However, due to the position control in the look-ahead approach, the follower vehicle may cut corners. To overcome this problem, the look-ahead is extended to a point perpendicular to the direction of the preceding vehicle, which can be viewed as a virtual preceding vehicle tracking objective. To demonstrate the effectiveness of the designed controller with the extended look-ahead approach, simulations are performed and further validated with experiments on a mobile robot platform. The results prove the effectiveness of the extended look-ahead approach. [ABSTRACT FROM AUTHOR]

Pain evaluation methods can represent pain information clearly yet inefficiently; they also cannot effectively display long-term pain records for review or comparison. They often must be supplemented by multidimensional scales with descriptors and labeled body figures. Pain is complicated to describe accurately, has a variety of causes, is related to pathology, and, in pain evaluation, needs improvements in information loss or incompleteness, dynamic pattern, long-term history tracking, and complexity and convenience of recording and maintaining this information. We propose a novel pain recording and tracking system using augmented reality (AR) that is complete and direct to use. Results show this app is reliable and appeals to users. [ABSTRACT FROM AUTHOR]

This paper presents an application-transparent execution context for mobile operating systems that reflects the criticality of current execution on the user interactivity. We track Android / Linux system-level events including semantic syscalls, UI actions, and standard inter-process and intra-process communication interfaces that signal the initiation and propagation of interactivity-related executions. This interactive context enables new optimizations in CPU scheduling and power state management. We recognize that online resource scheduling is susceptible to inaccurate contexts—e.g., misidentifying an interactive execution as background leads to possible priority inversion by schedulers. In particular, low-level OS events such as kernel block / wake-up carry ambiguous semantics that could induce false context propagations. We selectively expose such uncertainties to the schedulers so that executions with uncertain contexts are prioritized behind interactive executions but otherwise run as fast as possible to minimize the priority inversion. We further recognize the importance of prompt propagation of the interactivity context at the earliest possible moment to facilitate immediate prioritization. We utilize the interactivity context to enable differential per-core frequency control and background workload consolidation. Experiments on a quad-core smartphone with a dozen mobile workload scenarios show that we can, on average, save 13 percent energy with only 1 percent degradation on the interactive performance. [ABSTRACT FROM AUTHOR]

In this study, we present WindTalker, a novel and practical keystroke inference framework that can be used to infer the sensitive keystrokes on a mobile device through WiFi-based side-channel information. WindTalker is motivated from an observation that keystrokes on mobile devices will lead to different hand coverage and the finger motions, which will introduce a unique interference to the multi-path signals and can be reflected by the channel state information (CSI). An attacker can exploit the strong correlation between the CSI fluctuation and the keystrokes to infer the user's password input. Compared with the previous keystroke inference approaches, WindTalker neither deploys external equipment physically close to the target device nor compromises the target device. Instead, it employs a more practical setting by deploying a free public WiFi hotspot and collects the CSI data from the target device as long as the device is connected to the hotspot. In addition, to improve inference accuracy and efficiency, it analyzes the WiFi traffic to selectively collect CSI only for the sensitive period where password entering occurs. WindTalker can be implemented without the requirement of visually seeing the target device, or installing any malware on the device. We tested Windtalker on several mobile phones and performed a detailed case study to evaluate the practicality of the password inference towards Alipay, the largest mobile payment platform in the world. Furthermore, we proposed a novel CSI obfuscation countermeasure to thwart the inference attack. The evaluation results show that the performance of WindTalker can be dramatically reduced by adopting the proposed countermeasures. [ABSTRACT FROM AUTHOR]

The era of mobile communications and the Internet of Things (IoT) has introduced numerous challenges for mobile processing platforms that are responsible for increasingly complex signal processing tasks from different application domains. In recent years, the power efficiency of computing has been improved by adding more parallelism and workload-specific computing resources to such platforms. However, programming of parallel systems can be time-consuming and challenging if only low-level programming methods are used. This work presents a dataflow-based co-design framework TTADF that reduces the design effort of both software and hardware design for mobile processing platforms. The paper presents three application examples from the fields of video coding, machine vision, and wireless communications. The application examples are mapped and profiled both on a pipelined and a shared-memory multicore platform that is generated by TTADF. The results of the TTADF co-design-based solutions are compared against previous manually created designs and a recent dataflow-based design flow, showing that TTADF provides very high energy efficiency together with a high level of automation in software and hardware design. [ABSTRACT FROM AUTHOR]