Simplified Variants Research Articles

Connected and Autonomous Vehicle Scheduling Problems: Some Models and Algorithms

In this paper, we consider some problems that arise in connected and autonomous vehicle (CAV) systems. Their simplified variants can be formulated as scheduling problems. Therefore, scheduling solution algorithms can be used as a part of solution algorithms for real-world problems. For four variants of such problems, mathematical models and solution algorithms are presented. In particular, three polynomial algorithms and a branch and bound algorithm are developed. These CAV scheduling problems are considered in the literature for the first time. More complicated NP-hard scheduling problems related to CAVs can be considered in the future.

An ensemble learning framework for click-through rate prediction based on a reinforcement learning algorithm with parameterized actions

Click-through rate (CTR) prediction is essential for targeted advertising systems. Although there have been many studies on CTR prediction and forming some representative models, building a CTR prediction model that performs well under various scenarios remains a formidable challenge. Ensemble learning is a class of methods that improve the final performance by aggregating multiple base models. This paper proposes an ensemble learning framework that can predict the click probability for each ad impression by combining the results of one or more CTR prediction models. The framework utilizes an improved Reinforcement Learning (RL) algorithm that supports parametric operations to dynamically determine the models and their weights that participated in predicting CTR for each ad impression. Specifically, for each ad impression, the agent generates a discrete action and a continuous action vector based on predicted click-through rates by all base models. The discrete action determines the number of base models involved in prediction, while each continuous action decides the weight of each base model. We validate the ensemble learning framework on three benchmark datasets, including iPinYou, Criteo, and Avazu. The experimental results demonstrate that, in most cases, the ensemble learning framework outperforms the base models in terms of AUC and LogLoss metrics. Finally, we give two simplified variants of the ensemble learning framework and discuss their applicability.

Fatigue strength of the joint of steel cantilevers in composite bridges

AbstractBox girders with steel cantilevers underneath the deck are frequently used in the design of composite steel bridges. Hereby, the welded joints between the main girder and the transverse system have to endure fatigue loads. Current design specifications for this joint, e.g., a tapering in thickness of the top flanges at the same position of a transition radius, are complex to manufacture and provide a higher fatigue resistance than necessary. This article addresses the optimization of this structural detail, which is realized hundreds of times per structure. Several laboratory tests and numerical simulations were carried out regarding the load‐bearing behavior and the fatigue safety of the cantilevers as double‐T‐sections and as box girders. Additionally, 60 fatigue tests were conducted on small‐scale specimen to classify the resulting simplified design variants in detail categories of the nominal stress concept. As a result, two design recommendations are proposed for the joint at the intersecting top flanges. Moreover, the effect of an unplanned axial misalignment on the fatigue strength of the joint at the bottom flange is quantified.

Actuator line model using simplified force calculation methods

Abstract. To simulate transient wind turbine wake interaction problems using limited wind turbine data, two new variants of the actuator line technique are proposed in which the rotor blade forces are computed locally using generic load data. The proposed models, which are extensions of the actuator disk force models proposed by Navarro Diaz et al. (2019a) and Sørensen et al. (2020), only demand thrust and power coefficients and the tip speed ratio as input parameters. In the paper the analogy between the actuator disk model (ADM) and the actuator line model (ALM) is shown, and from this a simple methodology to implement local forces in the ALM without the need for knowledge of blade geometry and local airfoil data is derived. Two simplified variants of ALMs are proposed, an analytical one based on Sørensen et al. (2020) and a numerical one based on Navarro Diaz et al. (2019a). The proposed models are compared to the ADM using analogous data, as well as to the classical ALM based on blade element theory, which provides more detailed force distributions by using airfoil data. To evaluate the local force calculation, the analysis of a partial-wake interaction case between two wind turbines is carried out for a uniform laminar inflow and for a turbulent neutral atmospheric boundary layer inflow. The computations are performed using the large eddy simulation facility in Open Source Field Operation and Manipulation (OpenFOAM), including Simulator for Wind Farm Applications (SOWFA) libraries and the reference National Renewable Energy Laboratory (NREL) 5 MW wind turbine as the test case. In the single-turbine case, computed normal and tangential force distributions along the blade showed a very good agreement between the employed models. The two new ALMs exhibited the same distribution as the ALM based on geometry and airfoil data, with minor differences due to the particular tip correction needed in the ALM. For the challenging partially impacted wake case, both the analytical and the numerical approaches manage to correctly capture the force distribution at the different regions of the rotor area, with, however, a consistent overestimation of the normal force outside the wake and an underestimation inside the wake. The analytical approach shows a slightly better performance in wake impact cases compared to the numerical one. As expected, the ALMs gave a much more detailed prediction of the higher-frequency power output fluctuations than the ADM. These promising findings open the possibility to simulate commercial wind farms in transient inflows using the ALM without having to get access to actual wind turbine and airfoil data, which in most cases are restricted due to confidentiality.

Inconsistent illusory motion in predictive coding deep neural networks

Why do we perceive illusory motion in some static images? Several accounts point to eye movements, response latencies to different image elements, or interactions between image patterns and motion energy detectors. Recently PredNet, a recurrent deep neural network (DNN) based on predictive coding principles, was reported to reproduce the “Rotating Snakes” illusion, suggesting a role for predictive coding. We begin by replicating this finding, then use a series of “in silico” psychophysics and electrophysiology experiments to examine whether PredNet behaves consistently with human observers and non-human primate neural data. A pretrained PredNet predicted illusory motion for all subcomponents of the Rotating Snakes pattern, consistent with human observers. However, we found no simple response delays in internal units, unlike evidence from electrophysiological data. PredNet’s detection of motion in gradients seemed dependent on contrast, but depends predominantly on luminance in humans. Finally, we examined the robustness of the illusion across ten PredNets of identical architecture, retrained on the same video data. There was large variation across network instances in whether they reproduced the Rotating Snakes illusion, and what motion, if any, they predicted for simplified variants. Unlike human observers, no network predicted motion for greyscale variants of the Rotating Snakes pattern. Our results sound a cautionary note: even when a DNN successfully reproduces some idiosyncrasy of human vision, more detailed investigation can reveal inconsistencies between humans and the network, and between different instances of the same network. These inconsistencies suggest that predictive coding does not reliably give rise to human-like illusory motion.

Efficient automatic construction of atom-economical QM regions with point-charge variation analysis.

The setup of QM/MM calculations is not trivial since many decisions have to be made by the simulation scientist to achieve reasonable and consistent results. The main challenge to be tackled is the construction of the QM region to make sure to take into account all important parts of the adjacent environment and exclude less important ones. In our previous work [F. Brandt and Ch. R. Jacob, Systematic QM Region Construction in QM/MM Calculations Based on Uncertainty Quantification, J. Chem. Theory Comput., 2022, 18, 2584-2596.], we introduced the point charge variation analysis (PCVA) as a simple and reliable tool to systematically construct QM regions based on the sensitivity of the reaction energy with respect to variations of the MM point charges. Here, we assess several simplified variants of this PCVA approach for the example of catechol O-methyltransferase and apply PCVA for another system, the triosephosphate isomerase. Furthermore, we extend its scope by applying it to a DNA system. Our results indicate that PCVA offers an efficient and versatile approach of the automatic construction of atom-economical QM regions, but also identify possible pitfalls and limitations.

SYMBOLIC AI AND GÖDEL'S ONTOLOGICAL ARGUMENT

AbstractOver the past decade, variants of Gödel's ontological arguments have been critically examined using modern symbolic AI technology. Computers have unearthed new insights about them and even contributed to the exploration of new, simplified variants of the argument, which now need to be further investigated by theologians and philosophers. In this article, I provide a brief, informal overview of these contributions and engage in a discussion of the possible future role of AI technology for the rigorous assessment of arguments in theology and philosophy.

Experimental Verification of the Mechanical State Equation Adequacy for Description of the Creep of Some Polymer Materials under Non-stationary Modes of Static and Cyclic Loading in Plain Stress

The equation of mechanical condition for the description of deformation of polymer and polymer composite materials under complex modes of long static and cyclic loading in condition of the plain stress state is developed. The experimental data show its efficiency. The means of accounting the influence of natural aging and the damage accumulation data of a material are suggested. The opportunity of using of a simplified variants of the equation is shown.

The Use of the Integral Method in the Determination of the Mayr-Voronin and Cassie-Voronin Simplified Mathematical Models of Electric Arc with the Changeable Length of the Plasma Column

The article discusses the possibility of extending the usability of wellknown integral method formulas used to determine the parameters of the Mayr and Cassie mathematical models of fixed-length arc. Simulation tests discussed in the article involved the simplified variants of the Mayr-Voronin and Cassie-Voronin models of electric arc with dissipated power proportional to the volume of the elongated column. Results obtained in the tests proved the usability of the above-named formulas when calculating the parameters of modified arc models within a wide range of elongation rate changes.

New computer technologies to determine postmortem interval by the Henssge method

Background: The Henssge method is still the main thermometric method to determine postmortem interval. However, its existing software implementations are characterized by several disadvantages associated with copying simplified nomographic variants of the original mathematical models without any optimization attempts, as well as procedural imperfection in finding the roots of implicit functions. In this paper, methods are proposed for optimizing solutions to the Henssge mathematical models and determine their errors, as well as software application implementation. Aim: Optimization of the Henssge algorithm and development of a series of applications based on the obtained data, designed to determine postmortem interval. Material and methods: Methods for solving double exponential Henssge models and determining their errors based on computational mathematics and regression modeling using the least-squares method with subsequent implementation in the format of computer programs in C# language optimized. Results: The discrete nature of residual variance changes of the double exponential Henssge models intended to determine the postmortem interval according to rectal and cranioencephalic thermometry data under constant external temperature conditions is eliminated. The interval estimate determination of postmortem interval at any confidence probability is possible. The application program Warm Bodies HR was developed, which implements applied optimization methods. The application program Warm Bodies AHBG, designed to determine postmortem interval by the Henssge method in a single discrete decrease or increase conditions in the constant temperature of the external environment, including a change in the cooling conditions of the corpse, was developed. The search for the roots of implicit functions in programs is carried out using the Newton tangent method, which ensures continuous source data nature and eliminates errors associated with the need to round directly measured physical quantities. Conclusions: The developed programs are recommended for forensic medical expert practice to determine postmortem interval.

Uncertainty in phytoplankton-based lake ecological status classification: Implications of sampling frequency and metric simplification

We examined the influence of sampling frequency and the elimination of selected metrics from the Phytoplankton Multimetric for Polish Lakes (PMPL index) on lake ecological status classification. The effect of sampling frequency was analysed by calculating the official PMPL index using data from four sampling periods (848 lake-years; 478 Polish lakes), and compared the Pmpl-based classification to that assessed from PMPL variants calculated using one, two and three sampling periods. The effect of metric elimination was analysed by comparing the official three-metric PMPL classification with two variants, a one-metric PMPL including only the concentration of chlorophyll-a and a two-metric variant including total phytoplankton biomass and summer cyanobacterial biomass. Correlation strength between the official PMPL and simplified variants weakened by reducing sampling frequency but varied by period combinations. Uncertainty of ecological status classification increased in both simplification types but it was greatest when using the one-metric (chlorophyll-a based) variant. Sampling reduction from four to three periods resulted in 0.5–6.5% of lakes being over- or under-classified (total lake-year misclassification: 3.7–6.7%). Highest uncertainty of classification to at least good status occurred when the spring sampling period was excluded (6.5%). The risk of misclassification increased to 4.2–14.9% when two sampling periods were used. When classification was based only on a one-period (late summer) PMPL, 12.1% of lake-years were misclassified to at least good and 9.3% to below-good ecological status. The risk of misclassification to at least good ecological status was 2% when the two-metric (biomass-based) PMPL index was used and 28.9% when the one-metric (chlorophyll-a based) was used. Lowest misclassification error (0.5%–5.2%) occurred when a three-period (spring-August-October), three-metric PMPL index was used, but as this 5.2% would result in substantial status under-classification, we recommend further research to possibly optimize a three-period PMPL variant to reduce the costs of lake ecological monitoring in Poland.

Population-Based Novelty Searches Can Converge

Novelty search is a powerful tool for finding sets of complex objects in complicated, open-ended spaces. Recent empirical analysis on a simplified version of novelty search makes it clear that novelty search happens at the level of the archive space, not the individual point space. The sparseness measure and archive update criterion create a process that is driven by a clear pair of objectives: spread out to cover the space, while trying to remain as efficiently packed as possible driving these simplified variants to converge to an

Systematic simplification of the Anaerobic Digestion Model No. 1 (ADM1) – Model development and stoichiometric analysis

Rigorous process models provide a reliable basis for model-based monitoring and control of anaerobic digestion plants. Due to the complex model structure and non-linear system characteristics, the established Anaerobic Digestion Model No. 1 (ADM1) is rarely applied in industrial plant operation. The present investigation proposes a systematic procedure for successive model simplification and presents the description of five model variants of a mass-based ADM1. Individual model structures greatly differ in their number of implemented process phases, characteristic components and required parameters. Simplified model variants combine nutrient degradation and biogas formation based on first-order sum reactions, whereas complex model structures describe individual degradation pathways and intermediates during acido- and acetogenesis. Characteristic features of the derived model structures as well as the stoichiometric methane potentials and microbial biomass yields of the underlying degradation pathways of individual model variations are evaluated and discussed in detail.

CALCULUL CÂMPULUI ELECTRIC ASOCIAT UNUI CUPLOR INDUCTIV DESTINAT TRANSFERULUI DE PUTERE WIRELESS

"Contactless or wireless power transmission has become a widespread disruptive technology. Although known for more than 100 years, it is the result of the unprecedented development of microelectronics and power electronics in recent decades. Numerous technical solutions for near-field energy transmission at different power and frequency levels are currently established: capacitive electric field transmission (CPT), inductive magnetic field transmission (IPT), multi-coil transmission and simultaneous transmission via electric field and magnetic field as a combination of the first two. The materialization of the contactless transmission is achieved in theory and practice through different types of contactless coupling circuits, generically called ""contactless couplers"". The inductive coupler can be considered as an electrical transformer in air or with open magnetic circuit in which the primary (Tx) and the secondary winding (Rx) can occupy different positions from each other depending on the application [1]. It is considered a representative element for WPT (Wireless Power Transfer) systems currently used from transferred powers of several watts to tens or hundreds of kilo-watts. To increase the transfer efficiency, the coupler works at high frequencies, of the order of kHz or MHz and in some cases has planar windings, of different shapes, made of litz wire and usually has magnetic flux concentrators [2]. Any inductive coupler is integrated into a complex transmission system, consisting of many other components [3]. In addition to the electromagnetic calculation widely presented in other works, open magnetic circuit construction produces electric and magnetic scattering fields that have a negative effect on both electrical and electronic equipment in the vicinity and on human health if the exposure exceeds certain thresholds. These thresholds are indicated by international standards and requirements [4-5] achieved by applying the precautionary principle [6] so that they can be reviewed periodically and are not mandatory unless they are taken over in national law. In this paper we analyze by the finite element method, in approximate 2D, the electric field produced by an inductive coupler in various simplified construction variants and calculate certain related quantities of practical importance such as: electric field distribution in the field of calculation, electric field strength in the vicinity of the inductive coupler, equipotential lines, reactive power, equivalent capacities."

Replacing the Rhamnose-Xylose Moiety of QS-21 with Simpler Terminal Disaccharide Units Attenuates Adjuvant Activity in Truncated Saponin Variants.

Adjuvants are key immunostimulatory components in vaccine formulations, which improve the immune response to the co‐administered antigen. The saponin natural product QS‐21 is one of the most promising immunoadjuvants in the development of vaccines against cancer and infectious diseases but suffers from limitations that have hampered its widespread human use. Previous structure–activity relationship studies have identified simplified saponin variants with truncated carbohydrate chains, but have not focused on the influence of the linear oligosaccharide domain of QS‐21 in adjuvant activity. Herein, an expeditious 15‐step synthesis of new linear trisaccharide variants of simplified QS‐21‐derived adjuvants is reported, in which the complex terminal xylose‐rhamnose moiety has been replaced with commercially available, simpler lactose and cellobiose disaccharides in a β‐anomeric configuration. In vivo immunological evaluation of the synthetic saponins showed attenuated antibody responses, highlighting the negative impact of such carbohydrate modifications on adjuvant activity, which could be associated with higher saponin conformational flexibility.

Computing the Growth of Small Cracks in the Assist Round Robin Helicopter Challenge

Sustainment issues associated with military helicopters have drawn attention to the growth of small cracks under a helicopter flight load spectrum. One particular issue is how to simplify (reduce) a measured spectrum to reduce the time and complexity of full-scale helicopter fatigue tests. Given the costs and the time scales associated with performing tests, a means of computationally assessing the effect of a reduced spectrum is desirable. Unfortunately, whilst there have been a number of studies into how to perform a damage tolerant assessment of helicopter structural parts there is currently no equivalent study into how to perform the durability analysis needed to determine the economic life of a helicopter component. To this end, the present paper describes a computational study into small crack growth in AA7075-T7351 under several (reduced) helicopter flight load spectra. This study reveals that the Hartman-Schijve (HS) variant of the NASGRO crack growth equation can reasonably accurately compute the growth of small naturally occurring cracks in AA7075-T7351 under several simplified variants of a measured Black Hawk flight load spectra.

Molecular Dynamics Simulations for Three-Dimensional Structures of Orotate Phosphoribosyltransferases Constructed from a Simplified Amino Acid Set.

Proteins of modern terrestrial organisms are composed of nearly 20 amino acids; however, the amino acid sets of primitive organisms may have contained fewer than 20 amino acids. Furthermore, the full set of 20 amino acids is not required by some proteins to encode their function. Indeed, simplified variants of Escherichia coli (E. coli) orotate phosphoribosyltransferase (OPRTase) constructed by Akanuma et al. and composed of a limited amino acid set exhibit significant catalytic activity for the growth of E. coli. However, its structural details are currently unclear. Here, we predict the structures of simplified variants of OPRTase using molecular dynamics (MD) simulations and evaluate the accuracy of the MD simulations for simplified proteins. The three-dimensional structure of the wild-type was largely maintained in the simplified variants, but differences in the catalyst loop and C-terminal helix were observed. These results are considered sufficient to elucidate the differences in catalytic activity between the wild-type and simplified OPRTase variants. Thus, using MD simulations to make structural predictions appears to be a useful strategy when investigating non-wild-type proteins composed of reduced amino acid sets.

The influence of channel network silting up at Žitný Ostrov to range of interaction between surface and groundwater

The movement of water resources, especially the possibilities of their regulation by interaction between surface and groundwaters are the subject matter of attention particularly during the occurrence of extreme hydrologic situation. This work presents the overview of knowledge and results which were achieved at IH SAS in this question. It can show the ways how to optimize the adjudicated processes which emerge during the requirement of emergency intervention. The solution of this task was located at the Žitný Ostrov area because this territory with their existence of channel network is suitable for studying the surface and groundwater interaction. The channel network at Žitný Ostrov was built up for drainage and also to safeguard irrigation water. The water level in the whole channel network system has an effect on groundwater level on the Žitný Ostrov and vice versa. It was been necessary to judge the impact of the channel network silting up by bed silts on the interaction between channel network and groundwater on the Žitný Ostrov. The aim was to evaluate the changes of bed silt state of Žitný Ostrov channel network and consecutively their influence on interaction processes between groundwater and surface water along the channels in the period from 1993 to present. The measurements of bed silt thickness in Žitný ostrov channel network had been started from1993, later they continued at selected profiles of three main channels – channel Gabčíkovo-Topoľníky, Chotárny channel and Komárňanský channel (for checking of the silting up variability). From 2008 the detailed field measurements of cross-section profiles aggradations along these selected three channels have been started. The objective of detailed field measurements was the determination of the silt permeability which is expressed by parameter of saturated hydraulic conductivity. This parameter was determined by two ways – as the saturated hydraulic conductivity obtained from disturbed samples of silt Kp and as the saturated hydraulic conductivity obtained from undisturbed samples of silt Kn. In the first case the granularity of silts was determined as a first step and then was computed their Kp from the empirical formulas according Bayer-Schweiger and Spacek. From undisturbed samples of silts which were extracted along the channels from top, middle and bottom layer of silts, were determined the values Kn by the laboratory falling head method. The valid values Kp on channel Gabčíkovo-Topoľníky ranged from 4,33 10-7 to 4,46.10-5 m s-1, on Chotárny channel from 5.98 10-5 to 2.14 10-6 m s-1 and on Komárňanský channel fluctuated from 1.93 10-6 – 6.09 10-5 m s-1. The valid values Kn on on channel Gabčíkovo-Topoľníky ranged from 5.21 10-8 – 4.18 10-3 m s-1 , on Chotárny channel ranged from 8.54 10-8 – 2.70 10-4 m s-1 and on Komárňanský channel fluctuated from 4.72 10-7 – 1.26 10-5 m s-1. The remarkable results were noticed by comparison of values of saturated hydraulic conductivity from disturbed and undisturbed samples Kp and Kn. On Chotárny channel the values of silt saturated hydraulic conductivity from undisturbed samples Kn approximately hundredfold decreased (from 10-6 to 10-8 m s-1). On Komárňanský channel the comparison of values Kp and Kn shown that the values Kn from undisturbed samples approximately tenfold descended against Kp.
 Simultaneously, the bed silts‘ impact on the groundwater recharge (saturated hydraulic conductivity of silt) was also examined. Determination of the total recharge amount was done by numerical simulation (model SKOKY) and by the so-called method of interaction formulas. These two approaches were applied at the Žitný Ostrov channel network. There were field measurements performed in monitored three main channels and adjacent to obtain correct input data. These characteristics were used for simulation and computation of total recharge along the channels. The total recharge amount was calculated for four alternatives of the surface water levels in the channel and the surroundings groundwater respectively. We chose four simplified variants with the same geological conditions in surroundings area of channels, only water levels of groundwater and in channels were modified. The results of the simulations seem to show greater impact of the silt in the case of outflow from the channels to the surroundings than the inflow into the channel from the surroundings.

Semi-Supervised Text Simplification with Back-Translation and Asymmetric Denoising Autoencoders

Text simplification (TS) rephrases long sentences into simplified variants while preserving inherent semantics. Traditional sequence-to-sequence models heavily rely on the quantity and quality of parallel sentences, which limits their applicability in different languages and domains. This work investigates how to leverage large amounts of unpaired corpora in TS task. We adopt the back-translation architecture in unsupervised machine translation (NMT), including denoising autoencoders for language modeling and automatic generation of parallel data by iterative back-translation. However, it is non-trivial to generate appropriate complex-simple pair if we directly treat the set of simple and complex corpora as two different languages, since the two types of sentences are quite similar and it is hard for the model to capture the characteristics in different types of sentences. To tackle this problem, we propose asymmetric denoising methods for sentences with separate complexity. When modeling simple and complex sentences with autoencoders, we introduce different types of noise into the training process. Such a method can significantly improve the simplification performance. Our model can be trained in both unsupervised and semi-supervised manner. Automatic and human evaluations show that our unsupervised model outperforms the previous systems, and with limited supervision, our model can perform competitively with multiple state-of-the-art simplification systems.

Comments on “On a Continuum Model for Avalanche Flow and Its Simplified Variants” by S. S. Grigorian and A. V. Ostroumov

This note first summarizes the history of the manuscript “On a Continuum Model for Avalanche Flow and Its Simplified Variants” by Grigorian and Ostroumov—published in this Special Issue—since the early 1990s and explains the guiding principles in editing it for publication. The changes are then detailed and some explanatory notes given for the benefit of readers who are not familiar with the early Russian work on snow avalanche dynamics. Finally, the editor’s personal views as to why he still considers this paper of relevance for avalanche dynamics research today are presented in brief essays on key aspects of the paper, namely the role of simple and complex models in avalanche research and mitigation work, the status and possible applications of Grigorian’s stress-limited friction law, and non-monotonicity of the dynamics of the Grigorian–Ostroumov model in the friction coefficient. A comparison of the erosion model proposed by those authors with two other models suggests to enhance it with an additional equation for the balance of tangential momentum across the shock front. A preliminary analysis indicates that continuous scouring entrainment is possible only in a restricted parameter range and that there is a second erosion regime with delayed entrainment.