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排序方式: 共有1592条查询结果,搜索用时 13 毫秒
91.
Scientometrics - Open Access (OA) initiatives and knowledge infrastructure represent vital elements for both producing significant changes in scholarly communication and reducing limitations of... 相似文献
92.
We are interested in an optimal packing density problem for material flows on conveyor belts in two spatial dimensions. The control problem is concerned with the initial configuration of parts on the belt to ensure a high overall flow rate and to further reduce congestion. An adjoint approach is used to compare the optimization results from the microscopic model based on a system of ordinary differential equations with the corresponding macroscopic model relying on a hyperbolic conservation law. Computational results highlight similarities and differences of both optimization models and emphasize the benefits of the macroscopic approach. 相似文献
93.
Simone Ceriani Giulio Fontana Alessandro Giusti Daniele Marzorati Matteo Matteucci Davide Migliore Davide Rizzi Domenico G. Sorrenti Pierluigi Taddei 《Autonomous Robots》2009,27(4):353-371
A trustable and accurate ground truth is a key requirement for benchmarking self-localization and mapping algorithms; on the
other hand, collection of ground truth is a complex and daunting task, and its validation is a challenging issue. In this
paper we propose two techniques for indoor ground truth collection, developed in the framework of the European project Rawseeds, which are mutually independent and also independent on the sensors onboard the robot. These techniques are based, respectively,
on a network of fixed cameras, and on a network of fixed laser scanners. We show how these systems are implemented and deployed,
and, most importantly, we evaluate their performance; moreover, we investigate the possible fusion of their outputs. 相似文献
94.
95.
The Cost of Irrigation Water Delivery: An Attempt to Reconcile the Concepts of Cost and Efficiency 总被引:2,自引:1,他引:1
This work discusses the conflict between two of the main objectives of the EU Water Framework Directive: cost recovery and
economic efficiency in the use of irrigation water. In the Mediterranean region, this conflict is commonly embedded in a state
of under-utilization of irrigation networks managed by Water User Associations (WUAs). This under-utilization arises from
factors independent of farmers’ choice, such as water shortage, crises in the sector, and changes to the Common Agricultural
Policy. This prevents the facilities from operating at the minimum average cost. This paper argues that farmers should not
suffer this inefficiency, which results in them paying higher water prices to cover the costs of water supply. Indeed, the
application of the Water Directive should be rethought, taking into account the specific problems related to irrigation in
the Mediterranean region. Based on an econometric analysis of the costs of water distribution in a WUA in Sardinia (Italy),
we propose a payment system based on two components. Primarily there is a fee related to the number of hectares under irrigation.
In addition there is a fee that considers the intensity of irrigation: this component is to encourage farmers to save water.
The results show that the proposed approach has some desirable effects, including higher rates of cost recovery and possibly
a reduction in the use of groundwater. Finally, the proposed system is not overly expensive for the rest of the community,
who must bear the costs of inefficiencies in the use of irrigation water that do not depend on choices of farmers. 相似文献
96.
Luca Lucchese Simone Leorin Guido M Cortelazzo 《IEEE transactions on image processing》2006,15(10):3008-3019
This paper presents a new and effective method for estimating two-dimensional affine transformations and its application to image registration. The method is based on matching polar curves obtained from the radial projections of the image energies, defined as the squared magnitudes of their Fourier transforms. Such matching is formulated as a simple minimization problem whose optimal solution is found with the Levenberg-Marquardt algorithm. The analysis of affine transformations in the frequency domain exploits the well-known property whereby the translational displacement in this domain can be factored out and separately estimated through phase correlation after the four remaining degrees of freedom of the affine warping have been determined. Another important contribution of this paper, emphasized through one example of image mosaicking and one example of remote sensing image registration, consists in showing that affine motion can be accurately estimated by applying our algorithm to the shapes of macrofeatures extracted from the images to register. The excellent performance of the algorithm is also shown through a synthetic example of motion estimation and its comparison with another standard registration technique. 相似文献
97.
Simone Fujii Ricardo Marcelo Reche Ribeiro Maria Brígida Dos Santos Scholz Elisabete Yurie Sataque Ono Cássio Egidio C Prete Eiko Nakagawa Itano Yoshio Ueno Osamu Kawamura Elisa Yoko Hirooka 《Food Additives & Contaminants》2006,23(9):902-909
The performance of an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) based on a monoclonal antibody (mAb) for ochratoxin A (OTA) detection was evaluated in a comparative study with high-performance liquid chromatography (HPLC) analysis using 68 freshly harvested coffee samples from the North of Paraná State, Brazil. The anti-OTA mAb showed high specificity and low cross-reactivity with OTA analogues (OTB and OTalpha), but cross-reacted with OTC. This ic-ELISA showed a detection limit of 3.75 ngg-1 sample, when compared to 0.80 ngg-1 by HPLC, with an ic-ELISA/HPLC correlation coefficient of 0.90. As regards OTA analysis of these coffee samples, natural contamination was detected in 10 samples (14.7%) by both methods, where the ic-ELISA values (range 3.9-7.3 ngg-1) were 1.1 to 1.6-fold higher than HPLC data (2.7-4.7 ngg-1). Five samples (7.4%) were OTA positive (range 0.84-1.30 ngg-1) only by HPLC assay, probably due to the higher detection limit reached by ic-ELISA. OTA was undetectable in 53 samples (77.9%) by both methods, while all positive samples (range 0.84-7.30 ngg-1) showed OTA levels lower than 8 ngg-1 (maximum limit recommended by the European Union). The matrix interference of green coffee was minimized by dilution of sample extracts before carrying out the ELISA assay. This mAb-based ic-ELISA can be effectively applied for OTA screening in coffee, because it is simple, sensitive and sample preparation is easy. 相似文献
98.
We prove that both the synchronous data-flow language Lustre restricted to types with finite values and the synchronous state-oriented language Argos are embedded in the synchronous paradigm Timed Concurrent Constraint Programming (tccp). In fact, for each of the two languages we provide a tccp language encoding it compositionally with respect to the syntax of programs and linearly with respect to the size of programs. Besides giving results of expressiveness for tccp, our encodings permit us to obtain a language tailored for programming reactive systems where both control handling aspects and data processing aspects are relevant.Author partially supported by MIUR progetto cofinanziato Modelli Formali per la Sicurezza e il Tempo and by ESPRIT Working Group Constraint Programming for Time Critical Applications, Project Number 23677Accepted in revised form 22 October 2003 by M. Broy, G. Lüttgen and M. Mendler 相似文献
99.
100.