This study proposes a visualization that can assist computer scientists and data scientists to make decisions by exploring technology trends. While it is important for them to understand the technology trends in the rapidly changing computer science and data science fields, it takes considerable time and knowledge to acquire good information about these trends. Particularly, data/computer scientists with little experience in the field find it difficult to obtain information on such trends. Therefore, we propose a visualization system that can easily and quickly explore the technology trends in computer and data science. This study aims to identify the key technologies and developers in a specific field, and other technologies deeply related to specific technologies, and explore the changes in popularity of technologies, languages, and libraries over time. This study includes two case studies to obtain information using the proposed visualization. We demonstrate our system with GitHub repositories data.

ABSTRACT The vector decomposition problem has been considered as a hard problem, which is applicable to cryptography. Okamoto and Takashima proposed various types of public key cryptographic schemes based on the VDP. In this paper, we study the cryptographic implications of Okamoto‐Takashima schemes with respect to the properties of public keys. In the public key cryptography, one public key is associated to a unique private key, and an action using the public key implicitly assumes that the corresponding private action can be done only with the corresponding private key. We formalize this security issue by introducing the notion of equivalent public keys. We show that equivalent public keys exist in the Okamoto‐Takashima basic signature scheme and the homomorphic encryption scheme. We present a strong key substitution attack to their basic signature. We suggest how to prevent equivalent public keys and strong key substitution attack in their signature scheme. We point out that there are cases with no efficient methods to prevent equivalent public keys in their encryption scheme. Copyright © 2013 John Wiley & Sons, Ltd.

ABSTRACT Redactable signature schemes permit deletion of arbitrary substrings of a signed document while preserving the authenticity of the remaining document. Most of known redactable signatures based on pairing have large‐sized signatures and the sizes depend on the product of security parameter and the number of blocks of the redacted document. In this paper, we present a short redactable signature scheme based on pairing. We modify Waters signature scheme to obtain an underlying standard signature defined on composite‐order bilinear group. The modified scheme satisfies the unforgeability under the known message attack based on the Computational Diffie–Hellman assumption. Based on the modified Waters signature, we propose a short redactable signature that is existentially unforgeable under random message attack and weakly private. The size of the proposed scheme is 20% of known redactable signatures using aggregated pairing‐based signatures when half of the message blocks are deleted. Copyright © 2011 John Wiley & Sons, Ltd.

In this paper, we propose a new method for constructing a bilinear pairing over (hyper)elliptic curves, which we call the R-ate pairing. This pairing is a generalization of the Ate and Ateipairing, and can be computed more efficiently. Using the R-ate pairing, the loop length in Miller's algorithm can be as small as log (r1/phi(k)) some pairing-friendly elliptic curves which have not reached this lower bound. Therefore, we obtain savings of between 29% and 69% in overall costs compared to the Ateipairing. On supersingular hyperelliptic curves of genus 2, we show that this approach makes the loop length in Miller's algorithm shorter than that of the Ate pairing.

This paper presents stability analysis and experimental results of the nonlinear bang-bang impact controller for robotic manipulators. A stability condition has been derived based on the analysis in Ln ∞ space and its physical interpretation has been given. The analysis shows that the stability of nonlinear bang-bang impact control depends on sampling time and the accuracy of inertia estimation. Stability is enhanced with the decrease of changes in the Coriolis, centrifugal, and disturbance forces. The stability condition is verified by simulations and experiments. Experiments show that overall performance is comparable to or better than existing impact control techniques which employ more complicated control strategies.

For stabilization of a robot manipulator upon collision with a stiff environment, a nonlinear bang-bang impact controller is developed. Under this control, a robot can successfully achieve contact tasks without changing control algorithm or controller gains throughout all three modes: free space, transition and constrained motion. It uses a robust hybrid impedance/time-delay control algorithm to absorb impact forces and stabilize the system. This control input alternates with zero when no environment force is sensed due to loss of contact. This alternation of control action repeats until the impact transient subsides and steady state is established. After impact transient, the hybrid impedance/time-delay control algorithm is utilized. This bang-bang control method provides stable interaction between a robot with severe nonlinear joint friction and a stiff environment and achieves rapid response while minimizing force overshoots. During contact transition, we employ one simple control algorithm with same gains that switches only to zero, while other controllers use more than one control algorithms or different control gains. It is shown via experiments that overall controlled performance is superior or comparable to existing impact force control techniques.