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关键词： Wireless fidelity   Servers   Reliability   Performance evaluation   Hardware   Global Positioning System   Computer science   Senor network   mobile computing   Bluetooth   beacon   instant delivery  

摘要： We report a 3-year city-wide study of an operational indoor sensing system based on Bluetooth Low Energy (BLE) calledaBeacon (short for alibaba Beacon). aBeacon is pilot-studied, A/B tested, deployed, and operated in Shanghai, China to infer the indoor status of Alibaba couriers, e.g., arrival and departure at the merchants participating in the Alibaba Local Services platform. In its full operation stage (2018/01-2020/04),aBeacon consists of customized BLE devices at 12,109 merchants, interacting with 109,378 couriers to infer their status to assist the scheduling of 64 million delivery orders for 7.3 million customers with a total amount of $600 million order values. Although in an academic setting, using BLE devices to detect arrival and departure looks straightforward, it is non-trivial to design, build, deploy, and operateaBeacon from its conception to its retirement at city scale in a metric-based approach by considering the tradeoffs between various practical factors (e.g., cost and performance) during long-term system evolution. We report our study in two phases, i.e., an 8-month pilot study and a 28-month deployment and operation in the wild. We focus on an in-depth reporting on the five lessons learned and provide their implications in other systems with long-term operation and broad geospatial coverage, e.g., Edge Computing.

关键词： Computer Science   general   Software Engineering/Programming and Operating Systems   Operating Systems   Software Engineering   Artificial Intelligence  

摘要： The design of a certified program for the Karatsuba method to multiply univariate polynomials is described. A machine-checked proof of the equivalence between the simplest method for polynomial multiplication and the Karatsuba method is implemented. This is a small part of the DoCon-A library of certified computer algebra programs designed by the author of this paper. The equivalence is proved for an arbitrary commutative ring of coefficients, and our library includes a certified generation of commutative ring structure for domain R[x] of polynomials over any commutative ring R. The programs in the DoCon-A system include definitions of the corresponding mathematical concepts and proofs for the main properties of the methods implemented. These proofs are checked by the compiler. The purely functional programming language Agda, which supports dependent types, is used. General principles of designing certified programs in Agda are considered. A comparison with another approach to certified programming of the Karatsuba method is carried out.

关键词： Computer Science   general   Software Engineering/Programming and Operating Systems   Operating Systems   Software Engineering   Artificial Intelligence  

摘要： Based on Newton's recurrence formulas on the complex plane, the sums of values of one entire function at zeros of another entire function are found. This allows one to determine whether these functions have common zeros or not. An algorithm for computing an approximation to the resultant of a polynomial (or an entire function with a finite number of zeros) and an entire function is presented. The algorithm is implemented in the Maple computer algebra system. Examples that illustrate the operation of the algorithm are considered.

关键词： Memory management   Mice   Arrays   Random access memory   System-on-chip   Hash functions   Computer science   Estimator   sketches   generic counter   network measurement   compression   self-adaptive  

摘要： The Sketch is a compact data structure useful for network measurements. However, to cope with the high speeds of the current data plane, it needs to be held in the small on-chip memory (SRAM). Therefore, the product of the counter size and the number of counters must be below a certain limit. With small counters, some will overflow. With large counters, the total number of counters will be small, but each counter will be shared by more flows, leading to poor accuracy. To address this issue, we propose a generic technique: self-adaptive counters (SEAD Counter). When the value of the counter is small, it works as a standard counter. When the value of the counter is large however, we increment it using a predefined probability, so as to represent this large value. Moreover, in the SEAD Counter, the probability decreases when the value increases. We show that this technique can significantly improve the accuracy of counters. This technique can be adapted to different circumstances. We theoretically analyze the improvements achieved by the SEAD Counter. We further show that our SEAD Counter can be extended to three typical sketches and Bloom filters. We conduct extensive experiments on three real datasets and one synthetic dataset. The experimental results show that, compared with the state-of-the-art, sketches using the SEAD Counter improve the accuracy by up to 13.6 times, while the Bloom filters using SEAD Counter can reduce the false positive rate by more than one order of magnitude.

关键词： Portfolios   Training   Training data   Cybernetics   Parallel algorithms   Tuning   Computer science   Automatic portfolio construction (APC)   generative adversarial approach   parallel algorithm portfolio   parameter tuning  

摘要： Since automatic algorithm configuration methods have been very effective, recently there is increasing research interest in utilizing them for automatic solver construction, resulting in several notable approaches. For these approaches, a basic assumption is that the given training set could sufficiently represent the target use cases such that the constructed solvers can generalize well. However, such an assumption does not always hold in practice since in some cases, we might only have scarce and biased training data. This article studies effective construction approaches for the parallel algorithm portfolios that are less affected in these cases. Unlike previous approaches, the proposed approach simultaneously considers instance generation and portfolio construction in an adversarial process, in which the aim of the former is to generate instances that are challenging for the current portfolio, while the aim of the latter is to find a new component solver for the portfolio to better solve the newly generated instances. Applied to two widely studied problem domains, that is, the Boolean satisfiability problems (SAT) and the traveling salesman problems (TSPs), the proposed approach identified parallel portfolios with much better generalization than the ones generated by the existing approaches when the training data were scarce and biased. Moreover, it was further demonstrated that the generated portfolios could even rival the state-of-the-art manually designed parallel solvers.

关键词： mHealth   adherence   HIV   antiretroviral therapy   intervention development   mobile phone  

摘要： Background: The HIV epidemic in the Philippines is one of the fastest growing epidemics globally, and infections among men who have sex with men are rising at an alarming rate. The World Health Organization recommends the use of mobile health (mHealth) technologies to engage patients in care and ensure high levels of adherence to antiretroviral therapy (ART). Existing mHealth interventions can be adapted and tailored to the context and population served. Objective: This study aims to create a locally tailored intervention using a mobile phone platform to support treatment adherence for HIV patients on ART in the Philippines. Methods: A mixed methods approach guided by the Behavior Change Wheel framework was used to adapt an existing mHealth adherence support platform for the local setting and target population. A literature review, retrospective clinical record review, and focus group discussions with patients were conducted to understand the drivers of ART adherence and tailor the intervention accordingly. The resulting intervention was pilot-tested for 8 weeks, followed by focus group discussions with patients who received the intervention to assess the acceptability of the design. Results: Key issues contributing to nonadherence included side effects, lack of behavioral skills for pill taking, social support, mental health, and substance use. Patients identified mHealth as an acceptable mode of intervention delivery and wanted mHealth services to be highly personalizable. The study team, clinicians, and software developers integrated these findings into the intervention, which included a menu of services as follows: pill reminders, health tips, adherence feedback, appointment reminders, and symptom reporting. During the pilot phase, technical issues in the interactive voice response system (IVRS) were identified and addressed. Patients who participated in the pilot phase expressed a preference for SMS text messaging over the IVRS. Patients responded positively to

关键词： Task analysis   Noise measurement   Neurons   Machine learning algorithms   Computer science   Genetic algorithms   Autoencoder   class imbalance   classification   neural network   undersampling  

摘要： Machine learning models have gained popularity nowadays for their potential to solve real-life issues when trained on pertinent data. In many cases, the real-life data are class imbalanced and hence the corresponding machine learning models trained on the data tend to perform poorly on metrics like precision, recall, AUC, F1, and G-mean score. Since class imbalance issue poses serious challenges to the performance of trained models, a multitude of research works have addressed this issue. Two common data-based sampling techniques have mostly been proposed-undersampling the data of the majority class and oversampling the data of the minority class. In this article, we focus on the former approach. We propose two novel algorithms that employ neural network-based approaches to remove majority samples that are found to reside in the vicinity of the minority samples, thereby undersampling the former to remove (or alleviate) the imbalance issue. We delineate the proposed algorithms and then test the proposed algorithms on some publicly available imbalanced datasets. We then compare the performance of our proposed algorithms to other popular undersampling algorithms. Finally, we conclude that our proposed algorithms outperform most of the existing undersampling approaches on most performance metrics.

摘要： "I cannot work on what I cannot see…" ---Katherine Goble, Hidden Figures

关键词： Mineral Resources   Fossil Fuels (incl. Carbon Capture)   Geography   general   Sustainable Development   Statistics for Engineering   Physics   Computer Science   Chemistry and Earth Sciences   Mathematical Modeling and Industrial Mathematics  

关键词： Agriculture 4   0   Operator safety   Muscoskeletal disorders   Vibration risk   Machine learning   Ergonomics  

摘要： While being a fundamental driver of competitiveness in agroindustry, technological innovation has also introduced new critical elements related, for example, to the sustainability of the production processes as well as to the safety of workers. In such regard, the advent of the 4th industrial revolution (Agriculture 4.0) based on digitalization, is an unprecedented opportunity of rethinking the role of innovation in a new human-centric perspective. In particular, the establishment of an interconnected work environment and the augmentation of the operator's physical, sensorial, and cognitive capabilities, are two technologies which can be effectively employed for substantially improving the ergonomics and safety conditions on the workplace. This paper approaches such topic referring to the vibration risk, which is a well-known cause of work-related pathologies, and proposes an original methodology for mapping the risk exposure of the operators to the activities performed. A miniaturized wearable device is employed to collect vibration data, and the signals obtained are segmented in time windows and processed in order to extract the significant features. Finally, a machine learning classifier has been developed to recognize the worker's activity and to evaluate the related exposure to vibration risks. To validate the methodology proposed, an experimental analysis in real operating conditions has been finally carried out by monitoring the activities performed by a team of workers during harvesting operations. The results obtained demonstrate the feasibility and the effectiveness of the methodology proposed.