AlphaPilot: autonomous drone racing

Autonomous Robots - This paper presents a novel system for autonomous, vision-based drone racing combining learned data abstraction, nonlinear filtering, and time-optimal trajectory planning. The...     

Multi-perspective Navigation of Movies

Digital libraries of video are rapidly growing in size and availability through digital networks of computers. The explosion of digital unstructure information, such as video, traveling through the network raises the need for tools that allow video information structuring and “intelligent” access to sequences.In this paper we present a novel video database system, which has been expressly designed to support structured storage of movies. A semiotic formalization for movie logical organization is here introduced and exploited to derive the conceptual schema of an object-oriented movie database. This structure is expressly tailored to enable queries on film technical features and on semantic contents as well, thus allowing feature fusion and access from multiple perspectives. A novel visual interaction scheme is implemented that allows users to formulate queries as filtering operations, that enable focussing on the interesting part of information, while skipping the rest. Formalization of the operators of “perspective” and “filtering” is thereby supplied. Retrieval of stored sequences by iconic motion example is also implemented for accessing sequences by contents. Examples are supplied of interaction with the database and of expressive power of visual query language.     

Paillier''s Trapdoor Function Hides up to O ( n ) Bits

At EuroCrypt '99 Paillier proposed a new encryption scheme based on higher residuosity classes. The new scheme was proven to be one-way under the assumption that computing N -residuosity classes in Z _N2 ^* is hard. Similarly the scheme can be proven to be semantically secure under a much stronger decisional assumption: given w ∈ Z _N2 ^* it is impossible to decide if w is an N -residue or not. In this paper we examine the bit security of Paillier's scheme. We prove that if computing residuosity classes is hard, then given a random w it is impossible to predict the least significant bit of its class significantly better than at random. This immediately yields a way to obtain semantic security without relying on the decisional assumption (at the cost of several invocations of Paillier's original function). In order to improve efficiency we then turn to the problem of simultaneous security of many bits. We prove that Paillier's scheme hides n-b (up to O(n) ) bits if one assumes that computing the class c of a random w remains hard even when we are told that c<2 ^b . We thoroughly examine the security of this stronger version of the intractability of the class problem. An important theoretical implication of our result is the construction of the first trapdoor function that hides super-logarithmically (up to O(n) ) many bits. We generalize our techniques to provide sufficient conditions for a trapdoor function to have this property.     

Dating of newly formed minerals in geothermal fields through Th series short lived isotopes: Check on mineral of known age and implications to fluid-rock interactions

The ²²⁸Th/²²⁸Ra activity ratio can provide a tool for age measurements of newly formed minerals, down to about 15 yr. A general discussion of the method is followed by an experimental check on an aphthitalite brine, crystallized from a geothermal well at Cesano (Rome) in July, 1978 (the real age is 85 ± 5 months). It yielded an age of 75 + 8/-5 months through alpha-spectrometry activity measurements, and 85 ± 3 months through gamma-spectrometry activity measurements. A residence time of the fluid in the rock ranging from 3 to 10 centuries has been estimated by comparing the Ra isotopic composition of the fluid with the U/Th ratio of the wall rocks, according to a model proposed by Cherdyntsev (1971).     

Development and Experimental Analysis of a Soft Compliant Tactile Microsensor for Anthropomorphic Artificial Hand

This paper presents the development and preliminary experimental analysis of a soft compliant tactile microsensor (SCTM) with minimum thickness of 2 mm. A high shear sensitive triaxial force microsensor was embedded in a soft, compliant, flexible packaging. The performance of the whole system, including the SCTM, an electronic hardware and a processing algorithm, was evaluated by static calibration, maximum load tests, noise and dynamic tests, and by focusing on slippage experiments. A proper tradeoff between final robustness and sensitivity of the tactile device was identified. The experiments showed that the tactile sensor is sufficiently robust for application in artificial hands while sensitive enough for slip event detection. The sensor signals were elaborated with the cumulative summation algorithm and the results showed that the SCTM system could detect a slip event with a delay from a minimum of 24.5 ms to a maximum of 44 ms in the majority of experiments fulfilling the neurophysiological requirement.     

A mobile microrobot actuated by a new electromagnetic wobblemicromotor

Microactuators are perhaps the most critical components of micromechatronic systems. Micromotors with diameters in the range between 10-1 mm are needed, but are not readily available for practical use. This paper describes a teleoperated mobile microrobot, actuated by a new electromagnetic wobble micromotor, and designed to participate in the “International Micro Robot Maze Contest" organized every year in Nagoya, Japan. This competition is an excellent benchmark to compare the performance of different microactuators. The working principle, design, fabrication, and performance of the wobble micromotor are described. The microrobot has a volume of 1 cm³ and incorporates two wobble micromotors, the rotors of which are the driving wheels. The micromotor generates a torque of 350 μN·m at each step and a maximum speed of about 180 r/min. The operator controls the motion of the microrobot by a remote joystick connected to the microrobot by flexible ultraminiature wires. The microrobot is highly maneuverable, has a maximum speed of 10 cm/s and can climb a slope of 15°. Two microrobots, which differ only in some constructive details, were fabricated. A smaller version (4-mm diameter) of the wobble micromotor has been developed for use in an innovative miniature robot system for diagnosis and intervention in the colon     

A demand-assignment algorithm based on a Markov modulated chain prediction model for satellite bandwidth allocation

This article deals with the problem of the design of a control-based demand-assignment algorithm for a satellite access network using a Markov modulated chain traffic prediction model. The objective is to guarantee a target Quality of Service (QoS) to Internet traffic, while efficiently exploiting the air interface. The proposed algorithm is in charge of dynamically partitioning the uplink bandwidth capacity in a satellite spotbeam among the in-progress connections. Such partition is performed aiming at matching the QoS requirements of each connection and maximizing the satellite bandwidth exploitation. A closed-loop Control Theory approach is adopted to efficiently tackle the problem of the delay between bandwidth requests and bandwidth assignments, while minimizing the signaling overhead caused by control messages. The algorithm efficiently copes with both the satellite propagation delay and the delays inherent in the periodic nature of the bandwidth request mechanism. The proposed demand-assignment algorithm and Markov chain traffic prediction model are shown to improve the overall satellite network performance through extensive simulation experiments.     

Can Worms Be Good?

Since 1999 programmers and security analysts all over the world have been engaged in a debate over the use of malicious techniques for “constructive” purposes. The use of viral techniques as a means of solving problems implies certain risks. Here are some examples.