Search results for "Artificial"
showing 10 items of 7394 documents
Use of artificial substrates for sampling benthic macroinvertebrates in the assessment of water quality of large lowland rivers
2004
The objective of this investigation was to evaluate the usefulness of the artificial substrate sampler in collecting macroinvertebrates for water quality assessment of Polish lowland rivers. This paper presents the results of a comparative study between two different sampling techniques, i.e. nettings filled with brick as artificial substrates and handnet sampling. The validity of applying the biotic index method is also demonstrated. The Belgian Biotic Index (BBI) method and the lower Nysa Kłodzka river were chosen for study. Macroinvertebrates were collected seasonally at five sampling sites. Although some invertebrate taxa revealed a specific preference for one of the two tested sampling…
Post-operative computed tomography imaging evaluation of ascending aorta surgery
2021
Ascending thoracic aorta disease is often a life-threatening condition. Aortic aneurysm and aortic dissection are the most frequent ascending aorta diseases requiring surgical intervention. Surgical repair techniques of the ascending aorta are various; they include reconstruction of the ascending aorta by using a graft with or without a prosthetic valve, reconstruction with a composite artificial graft or using a biological graft, and reconstruction of the ascending aorta with a composite graft preserving the native valve and arch repair. The radiologist plays a key role in the identification of post-operative complications; differentiation from normal postoperative findings is fundamental.…
Towards Automatic Testing of Reference Point Based Interactive Methods
2016
In order to understand strengths and weaknesses of optimization algorithms, it is important to have access to different types of test problems, well defined performance indicators and analysis tools. Such tools are widely available for testing evolutionary multiobjective optimization algorithms. To our knowledge, there do not exist tools for analyzing the performance of interactive multiobjective optimization methods based on the reference point approach to communicating preference information. The main barrier to such tools is the involvement of human decision makers into interactive solution processes, which makes the performance of interactive methods dependent on the performance of huma…
An Artificial Decision Maker for Comparing Reference Point Based Interactive Evolutionary Multiobjective Optimization Methods
2021
Comparing interactive evolutionary multiobjective optimization methods is controversial. The main difficulties come from features inherent to interactive solution processes involving real decision makers. The human can be replaced by an artificial decision maker (ADM) to evaluate methods quantitatively. We propose a new ADM to compare reference point based interactive evolutionary methods, where reference points are generated in different ways for the different phases of the solution process. In the learning phase, the ADM explores different parts of the objective space to gain insight about the problem and to identify a region of interest, which is studied more closely in the decision phas…
Pirmie pavadoņu novērojumi Latvijas Universitātē pirms 60 gadiem
2018
Latvijas Universitātes Muzeja virtuālā izstāde „Pirmie pavadoņu novērojumi Latvijas Universitātē pirms 60 gadiem” stāsta par 1957. – 1958. gadu, kad tika palaisti pirmie Zemes mākslīgie pavadoņi. Universitātes astronomi aktīvi iesaistījās to novērošanā, jo bija nepieciešams noteikt pavadoņu orbītas. Sākumā notika pavadoņu vizuālie novērojumi, kuros bija iesaistīti daudzi studenti. Tā kā tie nebija pietiekami precīzi, astronomi sāka domāt par pavadoņu fotografēšanu. Pirmos uzņēmumus ieguva 1958. gadā uz LU galvenās ēkas jumta Raiņa bulvārī 19. Kamera, ar kuru tas veikts, glabājas Latvijas Universitātes Muzejā. Turpmākajos gados Latvijas Universitātes astronomi izvirzījās pavadoņu novērošanas…
Orientation Adaptive Minimal Learning Machine for Directions of Atomic Forces
2021
Machine learning (ML) force fields are one of the most common applications of ML in nanoscience. However, commonly these methods are trained on potential energies of atomic systems and force vectors are omitted. Here we present a ML framework, which tackles the greatest difficulty on using forces in ML: accurate prediction of force direction. We use the idea of Minimal Learning Machine to device a method which can adapt to the orientation of an atomic environment to estimate the directions of force vectors. The method was tested with linear alkane molecules. peerReviewed
Memory degradation induced by attention in recurrent neural architectures
2022
This paper studies the memory mechanisms in recurrent neural architectures when attention models are included. Pure-attention models like Transformers are more and more popular as they tend to outperform models with recurrent connections in many different tasks. Our conjecture is that attention prevents the recurrent connections from transferring information properly between consecutive next steps. This conjecture is empirically tested using five different models, namely, a model without attention, a standard Loung attention model, a standard Bahdanau attention model, and our proposal to add attention to the inputs in order to fill the gap between recurrent and parallel architectures (for b…
Setting the future of digital and social media marketing research: Perspectives and research propositions
2021
in press The use of the internet and social media have changed consumer behavior and the ways in which companies conduct their business. Social and digital marketing offers significant opportunities to organizations through lower costs, improved brand awareness and increased sales. However, significant challenges exist from negative electronic word-of-mouth as well as intrusive and irritating online brand presence. This article brings together the collective insight from several leading experts on issues relating to digital and social media marketing. The experts' perspectives offer a detailed narrative on key aspects of this important topic as well as perspectives on more specific issues i…
Application of a Knowledge Discovery Process to Study Instances of Capacitated Vehicle Routing Problems
2020
Vehicle Routing Problems (VRP) are computationally challenging, constrained optimization problems, which have central role in logistics management. Usually different solvers are being developed and applied for different kind of problems. However, if descriptive and general features could be extracted to describe such problems and their solution attempts, then one could apply data mining and machine learning methods in order to discover general knowledge on such problems. The aim then would be to improve understanding of the most important characteristics of VRPs from both efficient solution and utilization points of view. The purpose of this article is to address these challenges by proposi…
A trie-based approach for compacting automata
2004
International audience; We describe a new technique for reducing the number of nodes and symbols in automata based on tries. The technique stems from some results on anti-dictionaries for data compression and does not need to retain the input string, differently from other methods based on compact automata. The net effect is that of obtaining a lighter automaton than the directed acyclic word graph (DAWG) of Blumer et al., as it uses less nodes, still with arcs labeled by single characters.