Soft Subdivision Motion Planning for Complex Planar Robots

The design and implementation of theoretically-sound robot motion planning algorithms is challenging. Within the framework of resolution-exact algorithms, it is possible to exploit soft predicates for collision detection. The design of soft predicates is a balancing act between easily implementable predicates and their accuracy/effectivity. In this paper, we focus on the class of planar polygonal rigid robots with arbitrarily complex geometry. We exploit the remarkable decomposability property of soft collision-detection predicates of such robots. We introduce a general technique to produce such a decomposition. If the robot is an m-gon, the complexity of this approach scales linearly in m. This contrasts with the O(m^3) complexity known for exact planners. It follows that we can now routinely produce soft predicates for any rigid polygonal robot. This results in resolution-exact planners for such robots within the general Soft Subdivision Search (SSS) framework. This is a significant advancement in the theory of sound and complete planners for planar robots. We implemented such decomposed predicates in our open-source Core Library. The experiments show that our algorithms are effective, perform in real time on non-trivial environments, and can outperform many sampling-based methods

Rods and Rings: Soft Subdivision Planner for R^3 x S^2

We consider path planning for a rigid spatial robot moving amidst polyhedral obstacles. Our robot is either a rod or a ring. Being axially-symmetric, their configuration space is R^3 x S^2 with 5 degrees of freedom (DOF). Correct, complete and practical path planning for such robots is a long standing challenge in robotics. While the rod is one of the most widely studied spatial robots in path planning, the ring seems to be new, and a rare example of a non-simply-connected robot. This work provides rigorous and complete algorithms for these robots with theoretical guarantees. We implemented the algorithms in our open-source Core Library. Experiments show that they are practical, achieving near real-time performance. We compared our planner to state-of-the-art sampling planners in OMPL [Sucan et al., 2012]. Our subdivision path planner is based on the twin foundations of epsilon-exactness and soft predicates. Correct implementation is relatively easy. The technical innovations include subdivision atlases for S^2, introduction of Sigma_2 representations for footprints, and extensions of our feature-based technique for "opening up the blackbox of collision detection"

A New Design for Control Method Based on Hierarchical Deficit Round Robin Scheduler for EPON

With the development of ICT (Information and Communication Technology), how to use EPON for ensuring an effective and fair bandwidth allocation as well as the quality of service has become an important issue. Our research is based on Cousin Fair Hierarchical Deficit Round Robin Dynamic Bandwidth Allocation (CFHDRR DBA), which applies the concepts of hierarchical scheduling to reduce extra actions in information controlling and queue switching and DRR (Deficit Round Robin) to attain the goal of cousin fairness. Our research proposes three additional modules to CFHDDR DBA: (1) an admission control module, which limits the sum weight of QoS-controlled flow; (2) a weight partition module, which isolates the sum weight of other interfering flows from QoS-controlled flows; and (3) the quantum adaptation module, which minimizes the access time of QoS-controlled flows through  uantum distribution. With the help of OMNet++ simulation software, this research presents the improvement of CFHDRR by introducing dynamic DDR Quantum. In addition, it proposes admission control and bounded weight to keep the sum of flows within service capacity. The simulation result shows that, while keeping CFHDRR’s fairness, the queuing delay is reduced and the cycle time is effectively controlled so that the packet delay of QoS-controlled flows is minimized and QoS of real-time multimedia in EPON is fairly ensured

Vulnerability Assessment of IPv6 Websites to SQL Injection and Other Application Level Attacks

Given the proliferation of internet connected devices, IPv6 has been proposed to replace IPv4. Aside from providing a larger address space which can be assigned to internet enabled devices, it has been suggested that the IPv6 protocol offers increased security due to the fact that with the large number of addresses available, standard IP scanning attacks will no longer become feasible. However, given the interest in attacking organizations rather than individual devices, most initial points of entry onto an organization's network and their attendant devices are visible and reachable through web crawling techniques, and, therefore, attacks on the visible application layer may offer ways to compromise the overall network. In this evaluation, we provide a straightforward implementation of a web crawler in conjunction with a benign black box penetration testing system and analyze the ease at which SQL injection attacks can be carried out

Hybrid Network Defense Model Based on Fuzzy Evaluation

With sustained and rapid developments in the field of information technology, the issue of network security has become increasingly prominent. The theme of this study is network data security, with the test subject being a classified and sensitive network laboratory that belongs to the academic network. The analysis is based on the deficiencies and potential risks of the network’s existing defense technology, characteristics of cyber attacks, and network security technologies. Subsequently, a distributed network security architecture using the technology of an intrusion prevention system is designed and implemented. In this paper, first, the overall design approach is presented. This design is used as the basis to establish a network defense model, an improvement over the traditional single-technology model that addresses the latter’s inadequacies. Next, a distributed network security architecture is implemented, comprising a hybrid firewall, intrusion detection, virtual honeynet projects, and connectivity and interactivity between these three components. Finally, the proposed security system is tested. A statistical analysis of the test results verifies the feasibility and reliability of the proposed architecture. The findings of this study will potentially provide new ideas and stimuli for future designs of network security architecture

Exposure to Secondhand Smoke and Risk of Tuberculosis: Prospective Cohort Study

Background: Prospective evidence on the association between secondhand-smoke exposure and tuberculosis is limited. Methods: We included 23,827 never smokers from two rounds (2001 and 2005) of Taiwan National Health Interview Survey. Information on exposure to secondhand smoke at home as well as other sociodemographic and behavioral factors was collected through in-person interview. The participants were prospectively followed for incidence of tuberculosis through cross-matching the survey database to the national tuberculosis registry of Taiwan. Results: A total of 85 cases of active tuberculosis were identified after a median follow-up of 7.0 years. The prevalence of exposure to secondhand smoke at home was 41.8% in the study population. In the multivariable Cox proportional hazards analysis, secondhand smoke was not associated with active tuberculosis (adjusted hazard ratio [HR], 1.03; 95% CI, 0.64 to 1.64). In the subgroup analysis, the association between secondhand smoke and tuberculosis decreased with increasing age; the adjusted HR for those = 18 and = 40 and = 60 years old was 8.48 (0.77 to 93.56), 2.29 (0.75 to 7.01), 1.33 (0.58 to 3.01), and 0.66 (0.35 to 1.23) respectively. Results from extensive sensitivity analyses suggested that potential misclassification of secondhand-smoke exposure would not substantially affect the observed associations. Conclusions: The results from this prospective cohort study did not support an overall association between secondhand smoke and tuberculosis. However, the finding that adolescents might be particularly susceptible to secondhand smoke's effect warrants further investigation

External-Memory Graph Algorithms

We present a collection of new techniques for designing and analyzing efficient external-memory algorithms for graph problems and illustrate how these techniques can be applied to a wide variety of specific problems. Our results include: Proximate-neighboring. We present a simple method for deriving external-memory lower bounds via reductions from a problem we call the “proximate neighbors” problem. We use this technique to derive non-trivial lower bounds for such problems as list ranking, expression tree evaluation, and connected components. PRAM simulation. We give methods for efficiently simulating PRAM computations in external memory, even for some cases in which the PRAM algorithm is not work-optimal. We apply this to derive a number of optimal (and simple) external-memory graph algorithms. Time-forward processing. We present a general technique for evaluating circuits (or “circuit-like” computations) in external memory. We also usethis in a deterministic list ranking algorithm. Deterministic 3-coloring of a cycle. We give several optimal methods for 3-coloring a cycle, which can be used as a subroutine for finding large independent sets for list ranking. Our ideas go beyond a straightforward PRAM simulation, and may be of independent interest. External depth-first search. We discuss a method for performing depth first search and solving related problems efficiently in external memory. Our technique can be used in conjunction with ideas due to Ullman and Yannakakis in order to solve graph problems involving closed semi-ring computations even when their assumption that vertices fit in main memory does not hold. Our techniques apply to a number of problems, including list ranking, which we discuss in detail, finding Euler tours, expression-tree evaluation, centroid decomposition of a tree, least-common ancestors, minimum spanning tree verification, connected and biconnected components, minimum spanning forest, ear decomposition, topological sorting, reachability, graph drawing, and visibility representation