2,831 research outputs found
Privacy-Preserving Electronic Ticket Scheme with Attribute-based Credentials
Electronic tickets (e-tickets) are electronic versions of paper tickets,
which enable users to access intended services and improve services'
efficiency. However, privacy may be a concern of e-ticket users. In this paper,
a privacy-preserving electronic ticket scheme with attribute-based credentials
is proposed to protect users' privacy and facilitate ticketing based on a
user's attributes. Our proposed scheme makes the following contributions: (1)
users can buy different tickets from ticket sellers without releasing their
exact attributes; (2) two tickets of the same user cannot be linked; (3) a
ticket cannot be transferred to another user; (4) a ticket cannot be double
spent; (5) the security of the proposed scheme is formally proven and reduced
to well known (q-strong Diffie-Hellman) complexity assumption; (6) the scheme
has been implemented and its performance empirically evaluated. To the best of
our knowledge, our privacy-preserving attribute-based e-ticket scheme is the
first one providing these five features. Application areas of our scheme
include event or transport tickets where users must convince ticket sellers
that their attributes (e.g. age, profession, location) satisfy the ticket price
policies to buy discounted tickets. More generally, our scheme can be used in
any system where access to services is only dependent on a user's attributes
(or entitlements) but not their identities.Comment: 18pages, 6 figures, 2 table
Service Virtualisation of Internet-of-Things Devices: Techniques and Challenges
Service virtualization is an approach that uses virtualized environments to
automatically test enterprise services in production-like conditions. Many
techniques have been proposed to provide such a realistic environment for
enterprise services. The Internet-of-Things (IoT) is an emerging field which
connects a diverse set of devices over different transport layers, using a
variety of protocols. Provisioning a virtual testbed of IoT devices can
accelerate IoT application development by enabling automated testing without
requiring a continuous connection to the physical devices. One solution is to
expand existing enterprise service virtualization to IoT environments. There
are various structural differences between the two environments that should be
considered to implement appropriate service virtualization for IoT. This paper
examines the structural differences between various IoT protocols and
enterprise protocols and identifies key technical challenges that need to be
addressed to implement service virtualization in IoT environments.Comment: 4 page
Low loss high index contrast nanoimprinted polysiloxane waveguides
Nanoimprint lithography is gaining rapid acceptance in fields as
diverse as microelectronics and microfluidics due to its simplicity high
resolution and low cost. These properties are critically important for the
fabrication of photonic devices, where cost is often the major inhibiting
deployment factor for high volume applications. We report here on the use
of nanoimprint technology to fabricate low loss broadband high index
contrast waveguides in a Polysiloxane polymer system for the first time
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Resection Cavity Contraction Effects in the Use of Radioactive Sources (1-25 versus Cs-131) for Intra-Operative Brain Implants.
Background and Objectives Intra-parenchymal brain surgical resection cavities usually contract in volume following low dose rate (LDR) brachytherapy implants. In this study, we systematically modeled and assessed dose variability resulting from such changes for I-125 versus Cs-131 radioactive sources. Methods Resection cavity contraction was modeled based on 95 consecutive patient cases, using surveillance magnetic resonance (MR) images. The model was derived for single point source geometry and then fully simulated in 3D where I-125 or Cs-131 seeds were placed on the surface of an ellipsoidal resection cavity. Dose distribution estimated via TG-43 calculations and biological effective dose (BED) calculations were compared for both I-125 and Cs-131, accounting for resection cavity contractions. Results Resection cavity volumes were found to contract with an effective half-life of approximately 3.4 months (time to reach 50% of maximum volume contraction). As a result, significant differences in dose distributions were noted between I-125 and Cs-131 radioactive sources. For example, when comparing with static volume, assuming no contraction effect, I-125 exhibited a 31.8% and 30.5% increase in D90 and D10 values (i.e., the minimal dose to 90% and 10% of the volume respectively) in the peripheral target areas over the follow-up period of 20.5 months. In contrast, Cs-131 seeds only exhibited a 1.44% and 0.64% increase in D90 and D10 values respectively. Such discrepancy is likewise similar for BED calculations. Conclusion Resection cavity contractions affects Cs-131 dose distribution significantly less than that of I-125 for permanent brain implants. Care must be taken to account for cavity contractions when prescribing accumulative doses of a radioactive source in performing the brain implant procedures
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VR teleoperation interface for learning loco-manipulation of humanoid robots
Our world is designed by humans, for humans. This makes humanoid robots the most suitable general-purpose platform to automate repetitive or dangerous tasks done by people. However, due to the complex dynamics and high degrees-of-freedom of humanoid robots as well as the shortage of demonstration data, research in robot learning for humanoids is scarce. To address these challenges, I present a VR interface named TRILL (TeleopeRation Interface for Learning Loco-manipulation) to collect human demonstrations for humanoid robots in both simulation and reality. The demonstrations are then used to train a baseline Imitation Learning algorithm that uses an underlying controller to abstract away the complexity of whole-body control. I further propose that by embedding this data collection mechanism in VR video games, we can amass a large-scale dataset of high quality human demonstrations that can drive the development of future autonomous humanoids. To illustrate the feasibility of this idea, we collect a small dataset on toy tasks in simulation and real robot using the VR interface. We then show that the trained policy can be deployed in simulation with a reasonable success rate. A video demo of the VR teleoperation can be found here: https://youtu.be/PNZTwtcRhVU.Computer Science
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