277 research outputs found
Hexapod Design For All-Sky Sidereal Tracking
In this paper we describe a hexapod-based telescope mount system intended to
provide sidereal tracking for the Fly's Eye Camera project -- an upcoming
moderate, 21"/pixel resolution all-sky survey. By exploiting such a kind of
meter-sized telescope mount, we get a device which is both capable of
compensating for the apparent rotation of the celestial sphere and the same
design can be used independently from the actual geographical location. Our
construction is the sole currently operating hexapod telescope mount performing
dedicated optical imaging survey with a sub-arcsecond tracking precision.Comment: Accepted for publication in PASP, 10 page
Benchmarking CPUs and GPUs on embedded platforms for software receiver usage
Smartphones containing multi-core central processing units (CPUs) and powerful many-core graphics processing units (GPUs) bring supercomputing technology into your pocket (or into our embedded devices). This can be exploited to produce power-efficient, customized receivers with flexible correlation schemes and more advanced positioning techniques. For example, promising techniques such as the Direct Position Estimation paradigm or usage of tracking solutions based on particle filtering, seem to be very appealing in challenging environments but are likewise computationally quite demanding. This article sheds some light onto recent embedded processor developments, benchmarks Fast Fourier Transform (FFT) and correlation algorithms on representative embedded platforms and relates the results to the use in GNSS software radios. The use of embedded CPUs for signal tracking seems to be straight forward, but more research is required to fully achieve the nominal peak performance of an embedded GPU for FFT computation. Also the electrical power consumption is measured in certain load levels.Peer ReviewedPostprint (published version
Observing and Improving the Reliability of Internet Last-mile Links
People rely on having persistent Internet connectivity from their homes and
mobile devices. However, unlike links in the core of the Internet, the links
that connect people's homes and mobile devices, known as "last-mile" links, are
not redundant. As a result, the reliability of any given link is of paramount
concern: when last-mile links fail, people can be completely disconnected from
the Internet.
In addition to lacking redundancy, Internet last-mile links are vulnerable to
failure. Such links can fail because the cables and equipment that make up
last-mile links are exposed to the elements; for example, weather can cause
tree limbs to fall on overhead cables, and flooding can destroy underground
equipment. They can also fail, eventually, because cellular last-mile links can
drain a smartphone's battery if an application tries to communicate when signal
strength is weak.
In this dissertation, I defend the following thesis: By building on existing
infrastructure, it is possible to (1) observe the reliability of Internet
last-mile links across different weather conditions and link types; (2) improve
the energy efficiency of cellular Internet last-mile links; and (3) provide an
incrementally deployable, energy-efficient Internet last-mile downlink that is
highly resilient to weather-related failures. I defend this thesis by
designing, implementing, and evaluating systems
Personal Data Management Systems: The security and functionality standpoint
International audienceRiding the wave of smart disclosure initiatives and new privacy-protection regulations, the Personal Cloud paradigm is emerging through a myriad of solutions offered to users to let them gather and manage their whole digital life. On the bright side, this opens the way to novel value-added services when crossing multiple sources of data of a given person or crossing the data of multiple people. Yet this paradigm shift towards user empowerment raises fundamental questions with regards to the appropriateness of the functionalities and the data management and protection techniques which are offered by existing solutions to laymen users. These questions must be answered in order to limit the risk of seeing such solutions adopted only by a handful of users and thus leaving the Personal Cloud paradigm to become no more than one of the latest missed attempts to achieve a better regulation of the management of personal data. To this end, we review, compare and analyze personal cloud alternatives in terms of the functionalities they provide and the threat models they target. From this analysis, we derive a general set of functionality and security requirements that any Personal Data Management System (PDMS) should consider. We then identify the challenges of implementing such a PDMS and propose a preliminary design for an extensive and secure PDMS reference architecture satisfying the considered requirements. Finally, we discuss several important research challenges remaining to be addressed to achieve a mature PDMS ecosystem
Survey and Systematization of Secure Device Pairing
Secure Device Pairing (SDP) schemes have been developed to facilitate secure
communications among smart devices, both personal mobile devices and Internet
of Things (IoT) devices. Comparison and assessment of SDP schemes is
troublesome, because each scheme makes different assumptions about out-of-band
channels and adversary models, and are driven by their particular use-cases. A
conceptual model that facilitates meaningful comparison among SDP schemes is
missing. We provide such a model. In this article, we survey and analyze a wide
range of SDP schemes that are described in the literature, including a number
that have been adopted as standards. A system model and consistent terminology
for SDP schemes are built on the foundation of this survey, which are then used
to classify existing SDP schemes into a taxonomy that, for the first time,
enables their meaningful comparison and analysis.The existing SDP schemes are
analyzed using this model, revealing common systemic security weaknesses among
the surveyed SDP schemes that should become priority areas for future SDP
research, such as improving the integration of privacy requirements into the
design of SDP schemes. Our results allow SDP scheme designers to create schemes
that are more easily comparable with one another, and to assist the prevention
of persisting the weaknesses common to the current generation of SDP schemes.Comment: 34 pages, 5 figures, 3 tables, accepted at IEEE Communications
Surveys & Tutorials 2017 (Volume: PP, Issue: 99
Integrated Control of Microfluidics â Application in Fluid Routing, Sensor Synchronization, and Real-Time Feedback Control
Microfluidic applications range from combinatorial chemical synthesis to high-throughput screening, with platforms integrating analog perfusion components, digitally controlled microvalves, and a range of sensors that demand a variety of communication protocols. A comprehensive solution for microfluidic control has to support an arbitrary combination of microfluidic components and to meet the demand for easy-to-operate system as it arises from the growing community of unspecialized microfluidics users. It should also be an easy to modify and extendable platform, which offer an adequate computational resources, preferably without a need for a local computer terminal for increased mobility. Here we will describe several implementation of microfluidics control technologies and propose a microprocessor-based unit that unifies them. Integrated control can streamline the generation process of complex perfusion sequences required for sensor-integrated microfluidic platforms that demand iterative operation procedures such as calibration, sensing, data acquisition, and decision making. It also enables the implementation of intricate optimization protocols, which often require significant computational resources. System integration is an imperative developmental milestone for the field of microfluidics, both in terms of the scalability of increasingly complex platforms that still lack standardization, and the incorporation and adoption of emerging technologies in biomedical research. Here we describe a modular integration and synchronization of a complex multicomponent microfluidic platform
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