Search results for "NIP"
showing 10 items of 775 documents
Compensation of compliance errors in parallel manipulators composed of non-perfect kinematic chains
2012
The paper is devoted to the compliance errors compensation for parallel manipulators under external loading. Proposed approach is based on the non-linear stiffness modeling and reduces to a proper adjusting of a target trajectory. In contrast to previous works, in addition to compliance errors caused by machining forces, the problem of assembling errors caused by inaccuracy in the kinematic chains is considered. The advantages and practical significance of the proposed approach are illustrated by examples that deal with groove milling with Orthoglide manipulator.
Compliance error compensation technique for parallel robots composed of non-perfect serial chains
2012
The paper presents the compliance errors compensation technique for over-constrained parallel manipulators under external and internal loadings. This technique is based on the non-linear stiffness modeling which is able to take into account the influence of non-perfect geometry of serial chains caused by manufacturing errors. Within the developed technique, the deviation compensation reduces to an adjustment of a target trajectory that is modified in the off-line mode. The advantages and practical significance of the proposed technique are illustrated by an example that deals with groove milling by the Orthoglide manipulator that considers different locations of the workpiece. It is also de…
Denoising Autoencoders for Fast Combinatorial Black Box Optimization
2015
Estimation of Distribution Algorithms (EDAs) require flexible probability models that can be efficiently learned and sampled. Autoencoders (AE) are generative stochastic networks with these desired properties. We integrate a special type of AE, the Denoising Autoencoder (DAE), into an EDA and evaluate the performance of DAE-EDA on several combinatorial optimization problems with a single objective. We asses the number of fitness evaluations as well as the required CPU times. We compare the results to the performance to the Bayesian Optimization Algorithm (BOA) and RBM-EDA, another EDA which is based on a generative neural network which has proven competitive with BOA. For the considered pro…
Reordering Method and Hierarchies for Quantum and Classical Ordered Binary Decision Diagrams
2017
We consider Quantum OBDD model. It is restricted version of read-once Quantum Branching Programs, with respect to "width" complexity. It is known that maximal complexity gap between deterministic and quantum model is exponential. But there are few examples of such functions. We present method (called "reordering"), which allows to build Boolean function $g$ from Boolean Function $f$, such that if for $f$ we have gap between quantum and deterministic OBDD complexity for natural order of variables, then we have almost the same gap for function $g$, but for any order. Using it we construct the total function $REQ$ which deterministic OBDD complexity is $2^{\Omega(n/\log n)}$ and present quantu…
RationalizeRoots: Software Package for the Rationalization of Square Roots
2019
The computation of Feynman integrals often involves square roots. One way to obtain a solution in terms of multiple polylogarithms is to rationalize these square roots by a suitable variable change. We present a program that can be used to find such transformations. After an introduction to the theoretical background, we explain in detail how to use the program in practice.
REDUCTION OF CONSTRAINT SYSTEMS
1993
Geometric modeling by constraints leads to large systems of algebraic equations. This paper studies bipartite graphs underlaid by systems of equations. It shows how these graphs make possible to polynomially decompose these systems into well constrained, over-, and underconstrained subsystems. This paper also gives an efficient method to decompose well constrained systems into irreducible ones. These decompositions greatly speed up the resolution in case of reducible systems. They also allow debugging systems of constraints.
Using manipulation techniques to distribute Covid-19 disinformation: example of Facebook pages
2021
Bakalaura darbs „Manipulācijas tehniku izmantošana COVID-19 dezinformācijas izplatīšanā: Facebook lapu piemērs” ir izstrādāts ar mērķi izpētīt, ar kādiem manipulatīvajiem līdzekļiem visbiežāk tiek izplatīta COVID-19 dezinformācija „Facebook” lapās. Darba teorētisko bāzi veido apskats par sociālajiem medijiem, medijpratību, dezinformāciju, manipulāciju un tās taktikām gan starppersonu komunikācijā, gan sociālo mediju vidē. Izvirzītā darba problēma – līdz ar COVID-19 vīrusa izplatīšanos, sociālo tīklu informatīvajā telpā parādās nepatiesas ziņas un sagrozīta informācija saistībā ar COVID-19 vīrusa uzliesmojumu, kas tiešā veidā ietekmē cilvēku domāšanu un rīcību. Empīriskajā daļā izmantotas tr…
Fauna Europaea: Hymenoptera - Apocrita (excl. Ichneumonoidea)
2015
Fauna Europaea provides a public web-service with an index of scientific names (including important synonyms) of all living European land and freshwater animals, their geographical distribution at country level (up to the Urals, excluding the Caucasus region), and some additional information. The Fauna Europaea project covers about 230,000 taxonomic names, including 130,000 accepted species and 14,000 accepted subspecies. This represents a huge effort by more than 400 contributing specialists throughout Europe and is a unique (standard) reference suitable for many users in science, government, industry, nature conservation and education. Hymenoptera is one of the four largest orders of inse…
Use of stable isotope analysis to evaluate the possible impact of fish migration on a lake biomanipulation
2007
1. A lake restoration project involving mass fish removals was started to improve further the water quality of a lake recovering from severe eutrophication. The effectiveness of such biomanipulation as a lake management option could be compromised if removed fish are rapidly replaced by large-scale immigration from a connected lake. 2. Stable isotope analysis (SIA) was used to examine the migrations of perch (Perca fluviatilis L.) and roach (Rutilus rutilus (L.)) between two connected lakes in central Finland, Jyvasjarvi and the larger Paijanne. Baseline δ15N signatures in primary consumers were significantly higher in Jyvasjarvi and this difference was reflected further up the food chain i…
Biomanipulating the drinking water reservoir of Estonia's capital city: Prospects for success
2008
The possibility of utilizing biomanipulation to improve the water quality of Tallinn's drinking water reservoir (Lake Ulemiste) was analysed on the basis of water quality data, test fishing by different methods, and earlier studies on aquatic plants, light climate and sediments. Eutrophic, polymictic Lake Ulemiste is characterized by a prevalence of high filamentous cyanobacteria biomass, rotifers in the zooplankton community, mature bream in the fish biomass, and a high density of planktivores (YOY perch). Several prerequisites for being a potential target for biomanipulation were identified, including (i) decreased external total phosphorus (TP) loading; and (ii) a sufficient stock of pis…