The roadmap approach to robot path planning is one of the earliest methods. Since then, many different algorithms for building roadmaps have been proposed and widely implemented in mobile robots but their use has always been limited to planning in static, totally known environments. In this paper we combine the use of dynamic analogical representations of the environment with an efficient roadmap extraction method, to guide the robot navigation and to classify the different regions of space in which the robot moves. The paper presents the general reference architecture for the robotic system and then focuses on the algorithms for the construction of the roadmap, the classification of the regions of space and their use in robot navigation. Experimental results indicate the applicability and robustness of this approach in real situations. 相似文献
Several areas of knowledge are being benefited with the reduction of the computing time by using the technology of graphics processing units (GPU) and the compute unified device architecture (CUDA) platform. In case of evolutionary algorithms, which are inherently parallel, this technology may be advantageous for running experiments demanding high computing time. In this paper, we provide an implementation of a co-evolutionary differential evolution (DE) algorithm in C-CUDA for solving min–max problems. The algorithm was tested on a suite of well-known benchmark optimization problems and the computing time has been compared with the same algorithm implemented in C. Results demonstrate that the computing time can significantly be reduced and scalability is improved using C-CUDA. As far as we know, this is the first implementation of a co-evolutionary DE algorithm in C-CUDA. 相似文献
Scientometrics - Current knowledge on peer review consists of general formulations of its goals and micro level accounts of its practice, while journals’ attempts to guide and shape peer... 相似文献
The problem of autonomous transportation in industrial scenarios is receiving a renewed interest due to the way it can revolutionise internal logistics, especially in unstructured environments. This paper presents a novel architecture allowing a robot to detect, localise, and track (possibly multiple) pallets using machine learning techniques based on an on-board 2D laser rangefinder only. The architecture is composed of two main components: the first stage is a pallet detector employing a Faster Region-Based Convolutional Neural Network (Faster R-CNN) detector cascaded with a CNN-based classifier; the second stage is a Kalman filter for localising and tracking detected pallets, which we also use to defer commitment to a pallet detected in the first stage until sufficient confidence has been acquired via a sequential data acquisition process. For fine-tuning the CNNs, the architecture has been systematically evaluated using a real-world dataset containing 340 labelled 2D scans, which have been made freely available in an online repository. Detection performance has been assessed on the basis of the average accuracy over k-fold cross-validation, and it scored 99.58% in our tests. Concerning pallet localisation and tracking, experiments have been performed in a scenario where the robot is approaching the pallet to fork. Although data have been originally acquired by considering only one pallet as per specification of the use case we consider, artificial data have been generated as well to mimic the presence of multiple pallets in the robot workspace. Our experimental results confirm that the system is capable of identifying, localising and tracking pallets with a high success rate while being robust to false positives.
A new ternary molybdenum chalcogenide has been found with composition InxMo15Se19. This compound crystallizes in the hexagonal space group P63/m, and shows both types of blocks Mo6Se8 and Mo9Se11. To our knowledge, this is the first Me9X11 unit ever observed in a material. It presents a homogeneity domain: 2, 9 < x < 3, 4. Substitution of sulphur and tellurium for selenium in In3.3Mo15Se19-yXy (X = S, Te) is possible in the limits 0 < y < 12 and 0 < y < 2 respectively. The new compound becomes a high field superconductor at low temperature. 相似文献
Solution processing of conjugated polymers into ordered self‐assembled precursors has attracted great interest in the past years owing to the ability to manipulate their structural and physical properties. Regioregular poly(3‐hexylthiophene) (P3HT) has become the benchmark polymer in this scenario, where ordered lamellar structures significantly improve carrier mobility of the thin films due to increased crystallinity, extended intrachain conjugation, and ordered interchain π‐stacking. Here, a new photoinduced approach is presented for the generation of highly ordered P3HT aggregate structures that is amenable to the use of visible light to control the aggregate formation. Strong intra‐ and interchain interactions in the solution precursors allow for permanent formation of localized and delocalized polarons that are stable for months. Spin‐coated thin films are found to preserve, in part, the morphological and physical properties of the aggregated P3HT solution precursors with high degree of crystallinity and short π‐stack interchain distances. 相似文献
A multiplierless architecture based on algebraic integer representation for computing the Daubechies 4-tap wavelet transform for 1-D/2-D signal processing is proposed. This architecture improves on previous designs in a sense that it minimizes the number of parallel 2-input adder circuits. The algorithm was achieved using numerical optimization based o exhaustive search over the algebraic integer representation. The proposed architecture furnishes exact computation up to the final reconstruction step, which is the operation that maps the exactly computed filtered results from algebraic integer representation to fixed-point. Compared to Madishetty et al. (IEEE Trans Circuits Syst I (Accepted, In Press), 2012a), this architecture shows a reduction of \(10\cdot n-3\) adder circuits, where \(n\) is the number of wavelet decomposition levels. Standard \(512\times 512\) images Mandrill, Lena, and Cameraman were submitted to digital realizations of both proposed algebraic integer based as well as fixed-point schemes, leading to quantifiable comparisons. The design is physically implemented for a 4-level 2-D decomposition using a Xilinx Virtex-6 vcx240t-1ff1156 FPGA device operating at up to a maximum clock frequency of 263.15 MHz. The FPGA implementation is tested using hardware co-simulation using an ML605 board with clock of 100 MHz. A 45 nm CMOS synthesis shows improved clock frequency of better than 500 MHz for a supply voltage of 1.1 V. 相似文献
The sponge Tethya lyncurium from the Northern Adriatic has been used as an experimental species.A method is outlined for preparation of DNA which yields a highly purified DNA with a double-strand (ds) molecular weight of 25 M-dalton between single-strand (ss) breaks, which when properly damaged can be cut opposite to ss-breaks with nuclease s1. The molecular weights of the resulting ds-DNA pieces and their distribution has been evaluated by electron microscope photographs.Sponges exposed to benzo[a]pyrene (BaP) in the dark only incorporate BaP-derivatives (BaPD) in small amounts, if any. However, in the presence of light, derivatization to BaP derivatives enables effective coupling to occur, as shown previously (R. K. Zahn et al., 1981). Sponges were exposed to radiolabeled BaP in the presence of light. Coupling of BaPD to the DNA as well as the induction of ss-breaks were measured.Light-mediated coupling is concentration dependent from 0.01 – 20 ppb BaP with a correlation coefficient of r = 0.84.Under conditions of possible repair, ss-breaks completely disappear from sponge DNA in the course of three weeks while a substantial fraction of the BaP derivatives persists.Double label experiments show that substantial DNA synthesis occurs during this time. Pollution causes a decrease of the molecular weight of unnicked DNA, re-incubation in clean water an increase. A DNA species of 24 M-dalton seems to play a critical role. If its percentage in the DNA population drops below a critical level, recovery is not longer possible. DNA damage by PAH and repair in sponges seems to differ from that of most eucaryotes. 相似文献
Reports an error in the original article by G. P. Lombardo and R. Foschi (History of Psychology, 2003, 2, 123-142). In the reference list, several works by Pierre Janet were identified as being Paul Janet. The correct references are provided, where Paul Janet is identified by the initial P. and Pierre Janet is identified by the initials P. M. F.. (The following abstract of this article originally appeared in record 2003-03729-003.) Since the 1920s, the road to the acknowledgment of personality psychology as a field of scientific psychology that has individuality as its object began with the founding of the discipline by Gordon W. Allport. Historians of psychology have made serious attempts to reconstruct the cultural, political, institutional, and chronological beginnings of this field in America in the 20th century. In this literature, however, an important European tradition of psychological studies of personality that developed in France in the 2nd half of the 19th century has been overlooked. The aim of this article is to cast some light on this unexplored tradition of psychological personality studies and to discuss its influence on the development of the scientific study of personality in the United States. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献