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34322. Simulated 3D biped walking with an evolution-strategy tuned spiking neural network
- Creator:
- Wiklendt, Lukasz, Chalup, Stephan K. , and Seron , María M.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Spiking neurons, evolution strategy, and biped locomotion
- Language:
- English
- Description:
- This paper presents the results of experiments in applying a spiking neural network to control the locomotion of a simulated biped robot. The neural model used in simulations was developed to allow for an analytic solution to a neuron fire time, while maintaining a non-instant post-synaptic potential rise time. The synaptic weights and delays were tuned using an evolution strategy. Simulation experiments demonstrate that within about seven thousand generations the biped is able to acquire a dynamic walk which allows it to walk upright for several metres.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
34323. Simulated annealing construction of shortest paths on incomplete graphs
- Creator:
- Pospíchal, Jiří and Kvasnička, Vladimír
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- simulated annealing, traveling salesman problem, and shortest paths on incomplete graphs
- Language:
- English
- Description:
- Simulated annealing construction of shortest (spanning/nonspanning and closed/open) paths on generál connected graphs is discussed. A brief graphtheoretical analysis of the problem is given. A theorem has been proved that for connected graphs the shortest paths are semielementary, that is each edge on the path is visited at most twice in opposite directions. This observation considerably reduces the search space. Tasks may be further specified depending on whether the initial and terminal vertices are given or not. Similarly, in construction of shortest open paths a subtask is considered when the path must visit a prescribed subset of graph vertices. Illustrative calculations demonstrate that the proposed method results for incomplete graphs in the paths that are dosely related to optimal solutions.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
34324. Simulated microgravity reduces proliferation and reorganizes the cytoskeleton of human umbilical cord mesenchymal stem cells
- Creator:
- Quynh Chi, Ho Nguyen, Nghia Son, Hoang, Chinh Chung, Doan, Dinh Huan, Le, Hong Diem, Tran, and Thanh Long, Le
- Format:
- počítač and online zdroj
- Type:
- model:article and TEXT
- Subject:
- proliferace buněk, cytoskelet, cell proliferation, cytoskeleton, human umbilical cord mesenchymal stem cells, simulated microgravity, 14, and 612
- Language:
- English
- Description:
- The cytoskeleton plays a key role in cellular proliferation, cellshape maintenance and internal cellular organization. Cells are highly sensitive to changes in microgravity, which can induce alterations in the distribution of the cytoskeletal and cell proliferation. This study aimed to assess the effects of simulated microgravity (SMG) on the proliferation and expression of major cell cycle-related regulators and cytoskeletal proteins in human umbilical cord mesenchymal stem cells (hucMSCs). A WST-1 assay showed that the proliferation of SMG-exposed hucMSCs was lower than a control group. Furthermore, flow cytometry analysis demonstrated that the percentage of SMG-exposed hucMSCs in the G0/G1 phase was higher than the control group. A western blot analysis revealed there was a downregulation of cyclin A1 and A2 expression in SMG-exposed hucMSCs as well. The expression of cyclin-dependent kinase 4 (cdk4) and 6 (cdk6) were also observed to be reduced in the SMG-exposed hucMSCs. The total nuclear intensity of SMG-exposed hucMSCs was also lower than the control group. However, there were no differences in the nuclear area or nuclear-shape value of hucMSCs from the SMG and control groups. A western blot and quantitative RT-PCR analysis showed that SMG-exposed hucMSCs experienced a downregulation of β-actin and α-tubulin compared to the control group. SMG generated the reorganization of microtubules and microfilaments in hucMSCs. Our study supports the idea that the downregulation of major cell cycle-related proteins and cytoskeletal proteins results in the remodeling of the cytoskeleton and the proliferation of hucMSCs., Ho Nguyen Quynh Chi, Hoang Nghia Son, Doan Chinh Chung, Le Dinh Huan, Tran Hong Diem, Le Thanh Long., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
34325. Simulating vertical flow wetlands using filter media with different grain sizes with the HYDRUS Wetland Module
- Creator:
- Pucher, Bernhard and Langergraber, Guenter
- Type:
- article, model:article, and TEXT
- Subject:
- treatment wetlands, vertical flow, french VF wetland, HYDRUS Wetland Module, and CW2D
- Language:
- Slovak
- Description:
- In this study, the simulation results of four vertical flow wetland systems using the HYDRUS Wetland Module are presented. The four wetland systems comprise three single-stage pilot scale systems and one full-scale two-stage system. The main difference between these systems is the filter media used, referred to as fine media, i.e., sand with a grain size distribution 0.063–4 mm, or coarse media, i.e., sand with grain size distributions between 1–4 mm, respectively. The water-flow simulation of each system is carried out using the single porosity van Genuchten-Mualem model. A good match between measured and simulated volumetric effluent flow rates could be achieved for all wetland systems. For reactive transport simulations, the CW2D biokinetic model was applied. First, simulations were run using the standard CW2D parameter set. For some systems, adjustments of the parameter set were needed in order to avoid unlimited bacteria growth. To better fit measured COD, NH4-N, and NO3-N effluent concentrations, adjustments of few parameters of the standard parameter set were required. The results show that for the VF wetlands with fine sand, no adjustments of the CW2D standard parameter set were needed, while for systems with coarser filter media as the main layer, the standard parameter set had to be adjusted to match simulated and measured effluent concentrations.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
34326. Simulation studies on the statistics of a multipulse laser radar working at the single photoelectron level
- Creator:
- Neubert, R.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- simulation studies, statistics, and multipulse laser radar
- Language:
- Czech
- Description:
- The residual ambiguity of a laser radar system using pulse trains from a mode locking laser has been investigated by computer simulation. Numerical results are given for pulse groups with Gaussian envelope. A slight modification of this signal shape results in strong reduction of the ambiguity.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
34327. Simulations of coupled non-isothermal soil moisture transport and evaporation fluxes in a forest area
- Creator:
- Shao, Wei, Su, Ye, and Langhammer, Jakub
- Type:
- article, model:article, and TEXT
- Subject:
- soil–vegetation–atmosphere transfer model, evaporation flux, soil moisture transport, and forest meteorology
- Language:
- Slovak
- Description:
- This study focuses on the quantification of non-isothermal soil moisture transport and evaporation fluxes in vegetated area. A one-dimensional numerical model is developed by integrating a multi-phase flow model with a twolayer energy-balance model. The non-isothermal multi-phase flow model solves four governing equations for coupled air, vapour, moisture, and heat transport in soil porous medium. The two-layer energy balance model estimates evaporation fluxes from transpiration, interception, and soil surface. The model was implemented to an oak forest area in Missouri, USA. For model calibration and validation, measurements of energy fluxes, soil moisture, and soil temperature were used. The proposed model is compared with a simple model that couples the Penman-Monteith equation with the Richards’ equation. The results indicate that the simple model underestimate the total evaporation rate. On the contrary, the proposed model includes a more detailed description of energy transfer, which could improve the accuracy in estimating evaporation rates. The proposed model could be a promising tool to quantify the energy and moisture fluxes in a soil-vegetation-atmosphere continuum in vegetated area.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
34328. Simulations of freshwater lens recharge and salt/freshwater interfaces using the HYDRUS and SWI2 packages for MODFLOW
- Creator:
- Szymkiewicz, Adam, Gumuła-Kawęcka, Anna, Šimůnek, Jirka, Leterme, Bertrand, Beegum, Sahila, Jaworska-Szulc, Beata, Pruszkowska-Caceres, Małgorzata, Gorczewska-Langner, Wioletta, Angulo-Jaramillo, Rafael, and Jacques, Diederik
- Type:
- article, model:article, and TEXT
- Subject:
- groundwater recharge, freshwater lenses, HYDRUS, SWI2, MODFLOW, and vadose zone
- Language:
- Slovak
- Description:
- The paper presents an evaluation of the combined use of the HYDRUS and SWI2 packages for MODFLOW as a potential tool for modeling recharge in coastal aquifers subject to saltwater intrusion. The HYDRUS package for MODFLOW solves numerically the one-dimensional form of the Richards equation describing water flow in variablysaturated media. The code computes groundwater recharge to or capillary rise from the groundwater table while considering weather, vegetation, and soil hydraulic property data. The SWI2 package represents in a simplified way variable-density flow associated with saltwater intrusion in coastal aquifers. Combining these two packages within the MODFLOW framework provides a more accurate description of vadose zone processes in subsurface systems with shallow aquifers, which strongly depend upon infiltration. The two packages were applied to a two-dimensional problem of recharge of a freshwater lens in a sandy peninsula, which is a typical geomorphologic form along the Baltic and the North Sea coasts, among other places. Results highlighted the sensitivity of calculated recharge rates to the temporal resolution of weather data. Using daily values of precipitation and potential evapotranspiration produced average recharge rates more than 20% larger than those obtained with weekly or monthly averaged weather data, leading to different trends in the evolution of freshwater-saltwater interfaces. Root water uptake significantly influenced both the recharge rate and the position of the freshwater-saltwater interface. The results were less sensitive to changes in soil hydraulic parameters, which in our study were found to affect average yearly recharge rates by up to 13%.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
34329. Simultaneous approximation by a class of Bernstein-Durrmeyer operators preserving linear functions
- Creator:
- Gonska, Heiner and Păltănea, Radu
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- positive linear operator, Bernstein-type operator, genuine Bernstein-Durrmeyer operator, simultaneous approximation, degree of approximation, and moduli of continuity
- Language:
- English
- Description:
- We introduce and study a one-parameter class of positive linear operators constituting a link between the well-known operators of S. N. Bernstein and their genuine Bernstein-Durrmeyer variants. Several limiting cases are considered including one relating our operators to mappings investigated earlier by Mache and Zhou. A recursion formula for the moments is proved and estimates for simultaneous approximation of derivatives are given.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
34330. Simultaneous approximation for Szász-Mirakian quasi-interpolants
- Creator:
- Guo, Shunsheng and Qi, Qiulan
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Szász-Mirakian quasi-interpolants, simultaneous approximation, direct and inverse theorems, and Ditzian-Totik modulus
- Language:
- English
- Description:
- We obtain simultaneous approximation equivalence theorem for Szász-Mirakian quasi-interpolants.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public