Directional Dependence Research Articles

Optimization of gas extraction of producing wells to increase the efficiency of condensate production

The article discusses ways to increase the efficiency of condensate production due to the optimal distribution of gas flows between producing wells. For a large number of wells, the solution of this problem becomes nontrivial and requires special methods of nonlinear optimization. The main aim of research is obtaining accurate solutions to the problem of optimizing condensate production using direct dependencies between gas and condensate production. The minimum set of reliable field information has been determined, which allows solving the problem of optimal distribution of gas production between wells at the maximum condensate flow rate. An optimization problem is formulated for this model. The conditions under which the initial problem is divided into a system of optimization subtasks for subgroups of wells are considered. By the method of pairwise optimization, analytical expressions were found for optimal ratios of gas flow rates in a group of wells. Based on the expressions obtained, an algorithm has been developed for the exact solution of the problem of short-term optimization of the well operation mode.

Additive manufacturing of functionally graded foams: Material extrusion process design, part design, and mechanical testing

Functionally graded foams (FGFs) were in-situ fabricated via material extrusion (MEX) additive manufacturing (AM) process. Foamable filaments loaded with thermally expandable microspheres (TEMs) at 8.0 wt% was first fabricated using a single screw extruder. The correlations between the resultant foam density and process factors, namely nozzle temperature (NT) and flow rate (FR) were established using a statistical analysis and the density predictability of the model was verified by experiment. With concurrent control of NT and FR, FGFs with density ranges as high as 0.86 g cm−3 were achieved within a single print. Various FGFs were designed using linear, concave, and convex density gradient functions. The density-process correlation model was then used to obtain the NT and FR parameters needed to produce the density values as demanded by the part design. FGFs along with their single density foam (SDF) counterparts were successfully printed with good dimensional stability. Under quasi-static compression testing, all FGFs showed higher energy absorption capacity at low stress levels, as compared to their SDF counterparts. Moreover, under impact conditions, a significant loading direction dependency was found for the FGFs. Overall, this work demonstrates the AM feasibility of FGFs as a single print with tailored density profiles which can be used in generative design optimization of AM parts for enhanced mechanical performance and other functionalities.

Challenges in learning foreign languages encountered by intermediate-level students

This article is dedicated to exploring and clarifying the challenges faced by intermediate-level learners aiming for advanced proficiency in a target language, but instead encountering a period of stagnation. Within this context, a survey of the studentsʼ expectations regarding learning outcomes revealed that the most highly valued achievement was the ability to conduct targeted searches on the Internet using their recently acquired language skills. Following closely was the recognition of the influential impact of fluent intercultural dialogue with foreigners as the second priority on the path to language proficiency. This capacity not only broadens professional horizons but also increases engagement in the virtual environment. Understanding studentsʼ needs is a fundamental task in education. To address this, we suggest a range of productive strategies and tools to evaluate intermediate-level learnersʼ needs. These include diagnostic evaluations, self-evaluation, needs analysis surveys, feedback monitoring, cultural competence assessment, learning style monitoring, technology usage and preferences, and continuous formative assessment. Applying these techniques allows educators to acquire a comprehensive understanding of studentsʼ requirements, inclinations, and obstacles. It empowers teachers to customize their pedagogical approaches and content, providing enhanced support to students navigating through the stagnation phase. Having determined studentsʼ expectations and the obstacles they faced at the intermediate level, the authors have drawn conclusions regarding the correlation between these factors, noting a direct dependency between them. The article proposes methods and approaches aimed at addressing the dissonance between learnersʼ expectations and demotivating difficulties. These approaches include a task-based approach, error correction, individualized feedback, cultural immersion, co-teaching for dual guidance, and peer collaboration. Additionally, it is suggested that to rectify occasional errors, teachers should engage students in methods involving open-ended questions. They should instruct students in skills relevant to effective conversational performance, such as opening conversations, turn-taking, interrupting, changing the subject, understanding adjacency pairs, and closing conversations.

The rock mechanical relevance of anisotropy in tunnel design

AbstractThe assumption of an isotropic material behaviour is still common practice for tunnel design. Strictly speaking, this assumption is only valid if the influence of directional dependencies on the resulting deformations and stresses is marginal. In lithologies that have a high degree of anisotropy, such as shales and phyllites, the orientation characteristics of material properties such as strength and stiffness should be taken into account in order to avoid serious misinterpretations of the bearing capacity and deformation characteristic of the surrounding rock and the tunnel lining. The main focus is to accurately distinguish between the different types and terminology of anisotropy.

Supplemental Material for One Step at a Time: A Statistical Approach for Distinguishing Mediators, Confounders, and Colliders Using Direction Dependence Analysis

Supplemental Material for One Step at a Time: A Statistical Approach for Distinguishing Mediators, Confounders, and Colliders Using Direction Dependence Analysis

An improved peridynamic model for failure analysis of composite laminates

The study presents an improved peridynamic (PD) model for predicting the failure mode of composite laminates without any limitation to fiber orientation. In order to describe the directional dependency of composite laminae, the structural rotation angle is introduced into the PD framework to overcome the flaw that the fiber orientation is a specific value in conventional PD models. In improved PD model (IPM), two types of material points are used to model laminated structures, and a new force function mapping relationship is derived to achieve stable load transfer between in-plane and interlayer material points. As a result, the discrete grid of in-plane material points do not have to coincide with interlayer material points, and the technical difficulties in modeling multilayer laminates with general layups can be addressed. Since the IPM matches the microscopic configuration of practical composite structures, these damage characteristics, such as the damage path, crack initiation point, etc., correlate well with the experimental results. The numerical accuracy of the developed PD model are verified by simulating a series of examples of composite laminae with different fiber orientations, and the damage example further demonstrates the strong capability of the IPM in capturing failure modes of laminates with general layup.

One step at a time: A statistical approach for distinguishing mediators, confounders, and colliders using direction dependence analysis.

In observational data, understanding the causal link when estimating the causal effect of an independent variable (x) on a dependent variable (y) often requires researchers to identify the role of a third variable in the x → y relationship. Mediation, confounding, and colliding are three key third-variable effects that yield different theoretical and methodological implications for drawing causal conclusions. Commonly used covariance-based statistical methods, such as linear regression and structural equation modeling, cannot distinguish these effects in practice, however. In this study, we introduce a statistical approach for distinguishing mediators, confounders, colliders, and potential M-bias structures that uses higher-order moment information from the data. We propose a two-step procedure that uses the Hilbert-Schmidt independence criterion within the direction dependence analysis framework. Results from Monte Carlo simulations show that our proposed approach accurately recovers the true data-generating process of the third variable. We provide an empirical example to demonstrate the application of our proposed approach in psychological research. Finally, we discuss implications and future directions of our work. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Основные статистические свойства излучения типа гектометровый континуум в околоземном пространстве

In this work, we have studied the recently discovered hectometric continuum radiation in near-Earth plasma. We have carried out a detailed statistical analysis of the occurrence of a hectometric continuum near Earth at distances 1.1–2 Re, where Re is the Earth radius, for a two-year period, using data from the ERG (Arase) satellite. We have established that the generation of the hectometric radiation depends on the local magnetic time. The continuum radiation of this type is shown to occur mainly at night and in the morning. We have also studied the dependence of the occurrence of hectometric radiation on geomagnetic activity and have demonstrated that there is no direct dependence of the occurrence of hectometric radiation on geomagnetic disturbances. Moreover, the statistical analysis made it possible to localize sources of radio emission of this type in near-Earth space and to show that the source(s) of generation of the hectometric continuum radiation is located at low latitudes.

RESULTS REGARDING SEASONAL ACTIVITY, TEMPERATURE CONDITIONS OF THE EXISTENCE OF IXODUS TICKS AND THEIR ROLE AS TRANSMITTERS OF LYME DISEASE

SUMMARY. Over the last 10 years, some countries in Europe have been troubled by the spread of infectious agents that are transmitted by ixodes ticks. Lyme disease is the most frequent ixodes tick-borne human disease in the world, with an estimated 85.500 patients annually.
 The aim – to analyze the relationships between Lyme disease appearance and Ixodes tick bites number, air temperature, and their role in the transmission of Lyme disease.
 Material and Methods. 798 ticks of Ixodes Ricinus were investigated. All ticks of the first type were found mainly in the city of Ternopil and Ternopil region, as well as some ticks were brought from Lviv, Ivano-Frankivsk and Rivne regions. The study was carried out using optical and electronic system SEO-IMAGLAB. Investigation of epidemiological state was carried out using the polymerase chain reaction (PCR) using amplifier method “ROTOR Gene-6000” in real time.
 Results. Our studies showed, that about 30 % of ticks removed from humans are carriers of pathogens. Females of ticks are more carriers of Borrelia Burgdorferi, and the nymphs are carriers of Anaplasma phagocytophilium and Borrelia Miyamotoi. Larvae can be human ectoparasites and tolerate all three pathogens of infectious diseases. Including a complex carrying, that is the simultaneosus transfer of pathogens of the two diseases. Taking into consideration the dynamics of the frequency of infection with ticks of Ixodes ricinus, were observed an increase number of females and nymphs that are carries of pathogens in the period of May-July, and then, decrease the frequency of their infection in August-October. Obviously, the main cause of these fluctuations is the temperature regime, which changes in the spring-summer-autumn periods. Thus, the average temperature in May-June was 18–23 °C, in July-August – 25–27°C, in September-October – 20–15°C. At a temperature of 10–12°C, the number of patients affected by ticks decreased. As a result of studies on the influence of seasonal changes on the degree of infection with ticks of Ixodes ricinus by pathogens of infectious diseases, it`s direct dependence on the temperature regime: at a temperature of about 18–15°C, the degree of infection in the nymph is 14%, and in females – 22 %, while at 25–28°C in the nymph this figure is 37 %, and in females – 72 %.
 Conclusions. Geographic and seasonal distribution of Lyme borreliosis, patient`s age, sex, and profession has disease-related effects on incidence.

Confidence in causal inference under structure uncertainty in linear causal models with equal variances

Abstract Inferring the effect of interventions within complex systems is a fundamental problem of statistics. A widely studied approach uses structural causal models that postulate noisy functional relations among a set of interacting variables. The underlying causal structure is then naturally represented by a directed graph whose edges indicate direct causal dependencies. In a recent line of work, additional assumptions on the causal models have been shown to render this causal graph identifiable from observational data alone. One example is the assumption of linear causal relations with equal error variances that we will take up in this work. When the graph structure is known, classical methods may be used for calculating estimates and confidence intervals for causal-effects. However, in many applications, expert knowledge that provides an a priori valid causal structure is not available. Lacking alternatives, a commonly used two-step approach first learns a graph and then treats the graph as known in inference. This, however, yields confidence intervals that are overly optimistic and fail to account for the data-driven model choice. We argue that to draw reliable conclusions, it is necessary to incorporate the remaining uncertainty about the underlying causal structure in confidence statements about causal-effects. To address this issue, we present a framework based on test inversion that allows us to give confidence regions for total causal-effects that capture both sources of uncertainty: causal structure and numerical size of non-zero effects.

The problem of political correctness in consecutive interpreting from Russian into English

The article discusses the notion of political correctness and its impact on the decision-making in interpreting from Russian into English in the sphere of politics. The correlation between the notions of political correctness and adequacy of translation is analyzed. Translations of V. Putin’s and S. Lavrov’s speeches and interviews are studied in terms of strategies and techniques employed by the interpreters for the sake of political correctness. Adequacy of translation is also assessed. Conclusions are drawn stating direct dependency of interpreters’ choices on the type of potential discrimination and on the communicative situation requirements. In case of potential discrimination based on gender, race, age, religion, health, appearance, sexual orientation or social status, the political correctness requirements normally do not come into conflict with the communicative situation requirements, so the interpreters use the corresponding English euphemistic equivalents or resort to transformations, mainly generalization. Nevertheless, when political correctness is aligned with political or economic issues, adequacy of translation tends to require direct naming of things, with political correctness waived. This allows to raise the question whether euphemization related to the description of a state’s outer policy or its economic consequences should be part of the sphere of political correctness.

VOC source apportionment: How monitoring characteristics influence positive matrix factorization (PMF) solutions

Positive matrix factorization (PMF) can be used to develop more targeted air quality mitigation strategies by identifying major sources of a pollutant in an area. This technique is dependent, however, on the ability of PMF to resolve factors that accurately represent all sources of that pollutant in an area. We investigated how the accuracy of PMF solutions might be influenced by monitoring data characteristics, such as temporal resolution, monitoring location, and species composition, to better inform the use of PMF in VOC mitigation strategies. We applied PMF to five VOC monitoring programs collected within a four-year period in Colorado and found generally consistent factors, which we identified as oil extraction, processing, and evaporation; natural gas; vehicle exhaust; and liquid gasoline/short-lived oil and gas. The main determinant influencing whether or not a dataset resolved each of these sources was whether the dataset had a comprehensive list of VOC species covering key species of each source. Pollution spikes were not well-modeled in any of the solutions. Hyperlocal and volatile chemical product factors expected to be resolved in the industrialized, urban location were also missing, highlighting three limitations of PMF analysis. Wind direction dependence and diurnal trends aided in source identification, suggesting that high-time resolution data is important for developing actionable PMF results. Based on these findings, we recommend that air monitoring for PMF-informed VOC mitigation efforts include high temporal resolution and a comprehensive array of VOC species.

High‐velocity ballistic response of AA 1100‐H14 based carbon‐fiber metal laminates: An experimental investigation

AbstractA detailed experimental investigation was carried out for the high‐velocity ballistic response of AA 1100‐H14 based carbon‐fiber metal laminates (FMLs). FMLs with different metal volume fractions and the same thickness of carbon‐epoxy fiber laminates were tested to examine the surface and internal damage. The ballistic performance parameters, namely % escalation in absorbed energy, specific energy absorbed, ballistic limit, specific perforation energy, first cracking energy, and global deformation profile, were studied and a comparison was drawn with pure carbons fiber reinforced epoxy composite laminates. Despite having greater thickness, pure carbon fiber‐reinforced epoxy composite laminates absorbed less impact energy than FMLs and failed catastrophically. For FMLs, the % escalation in the absorbed energy and the specific energy absorption kept increasing with the increasing impact velocity until the onset of perforation. Once the perforation started, both these parameters showed a decreasing trend. Thick FMLs absorbed a good amount of energy, leading to projectile recoil suffering minimal damage. The ballistic velocity, specific perforation energy, and first cracking energy on the front and rear face of FMLs layers showed an increasing trend. The minimum for the thinner and maximum for the thicker FMLs attributed to the large thickness and more metal volume fraction. Contrary to the large deformation of the impacting points, pure carbon fiber‐reinforced epoxy composite laminates showed very minimal deformation as compared to FMLs. The brittle nature of the epoxy resin resisted the deformation to a large extent leading to less energy absorption.Highlights High‐velocity ballistic response of AA 1100‐H14 based carbon‐FMLs was investigated. Ballistic performance parameters of FMLs were studied and was compared with carbons fiber reinforced composite laminates. The ballistic limit of FMLs showed a direct dependence its thickness and metal volume fraction. In the absence of any metallic layer, pure carbons fiber reinforced composite laminates absorbed less impact energy.

Interrelationships of entropy production and turbulence kinetic energy associated with simple angle and compound angle full coverage film cooling

The present paper compares experimentally-measured distributions of entropy generation with numerically-predicted distributions of streamwise vorticity, turbulence kinetic energy, and production of turbulence kinetic energy. These comparisons are provided for two full-coverage film cooling environments which are designed to model the thermal management arrangements employed for combustor liners within gas turbine engines. One of these arrangements includes alternating compound angle values of +30° in one row of holes, followed by −30° in the next row of holes. The other arrangement includes simple angle holes with a zero degree compound angle value. The associated full-coverage film cooled boundary layers are investigated within a double-wall cooling test facility wherein the air for each full-coverage film cooling arrangement is provided by an impingement jet array. Experimentally-measured entropy generation values are obtained from film cooled boundary layer measurements of local total pressure variations, obtained in isothermal flow, relative to the freestream values outside of the boundary layer. The resulting entropy generation values quantify second law losses, which are associated with aerodynamic gains. To obtain the associated numerical-prediction results for a steady-state, three-dimensional flow field, employed is the ANSYS FLUENT Version 2022 R2 computational code with a SST k–ω turbulence closure model. The resulting comparisons of entropy generation, streamwise vorticity, turbulence kinetic energy, and production of turbulence kinetic energy are provided for a blowing ratio BR of 2.9 for simple angle film cooling with a main flow Reynolds number Rems of 138,000, and for compound angle film cooling with a main flow Reynolds number Rems of 142,000. Overall, evidence is provided of strong relationships between local turbulence kinetic energy and local entropy production since the two quantities are highly correlated with each other over s substantial range of experimental conditions and configurations. For example, ratio of turbulence kinetic energy to entropy generation data collapse for Z/de values from 0 to 3.5 for Y/de = 0.5, Y/de = 1.5, and both film cooling arrangements. Here, the value of the TKE/Sgen ratio is approximately constant for these conditions, which evidences direct and simple dependences of local turbulence kinetic energy upon local entropy generation, even for lower magnitudes of Z/de. The direct and simple dependences of local turbulence kinetic energy upon local entropy generation are further illustrated by the simplicity of linear correlation equations, which represent physical behavior for different conditions and configurations. These correlation equations are developed for three arrangements, which are associated with X/de = 54.54.

Azimuth Angle Dependence of Polarized Infrared Spectra of Injection-Molded Polyoxymethylene.

Injection-molded polyoxymethylene (POM) has molecular chains mainly oriented in the injection direction. We investigated the directional dependence of the polarized infrared reflection and attenuated total reflection spectra by rotating the anisotropic POM sample. Because of the strong absorption and large frequency dispersion of the C-O vibration in the main-chain direction, we found phenomena such as shoulder wing generation that resulted from the mixing of optical responses attributed to the vibration in the main chain and that in the direction perpendicular to the main chain. The spectra of the directional dependence can be explained qualitatively because of the anisotropy of the mode with large frequency dispersion.

Climate Change Impacts on Shallow Landslide Events and on the Performance of the Regional Shallow Landslide Early Warning System of Piemonte (Northwestern Italy)

Shallow landslides are one of the most dangerous gravitational phenomena. They are responsible for more than 50% of causalities due to landslides in northwestern Italy in the last century. The aim of the research study presented here is focused on understanding if and how climate change influences the occurrence and behavior of this landslide type. A total of 120 widespread shallow landslide events have been analyzed from 1960 to 2019, taking into account the spatial and time distribution in association with related rainfall historical data elaborated by the Optimal Interpolation (OI) model. Results underline that shallow landslide events’ number (aggregated per five-year intervals) is characterized by a weak trend consisting of a slight increase in the Alps and a more pronounced decrease in the hilly and Apennines environments. In addition, the trend of the annual accumulated rainfall average shows a weak drop in the winter season of about 9 mm in ten years. Moreover, the rainy days have generally decreased over the hills and Apennines, while in the Alps, only in the summer season, with a decreasing rate of about 1.5 days every ten years. The rainfall trends are in accordance with those of shallow landslide events, pointing out the close and direct dependence of the shallow landslide events on the rainfall regime variations. The results obtained were also used to validate the robustness of the performance of the Regional Shallow Landslide Early Warning System adopted in Piemonte over the investigated period, confirming the effectiveness of the trigger thresholds used for the entire historical series and for different geographical areas.

The Impact of Coal Quality on the Generator’s Achieved Power of the 300 MW Thermal Power Plant

This paper discusses the results of monitoring the operation of the steam-turbine unit of the 300 MW thermal power plant over a period of 2 months. During the monitoring, coal samples were taken in front of the mill-fan (3 samples/day) and data were collected on the fuel load of the boiler, temperatures in the boiler, temperatures of flue gases, content of pollutants in flue gases and realized gross power on the generator. Based on the results of technical analyses of coal and collected data on the operation of the block, direct dependencies were established between the quality of coal expressed through the Lower Thermal Power (DTM) value, and the realized gross electric power on the generator, coal consumption and the content of pollutants in the flue gases of the thermal power plant.

Hemispherical power asymmetry in intensity and polarization for Planck PR4 data

One of the foundations of the Standard Model of Cosmology is statistical isotropy, which can be tested, among other probes, through the study of the Cosmic Microwave Background (CMB). However, a hemispherical power asymmetry on large scales has been reported for WMAP and Planck data by different works.The statistical significance is above 3σ for temperature, suggesting a directional dependence of the local power spectrum, and thus a feature beyond the ΛCDM model. With the third release of the Planck data (PR3), a new analysis was performed including the E-mode polarization maps, finding an asymmetry at a modest level of significance. In this work, we perform an asymmetry analysis in intensity and polarization maps for the latest Planck processing pipeline (PR4). We obtain similar results to those obtained with PR3, with a slightly lower significance (2.8% for the Sevem method)for the amplitude of the E-mode local variance dipole as well as a significant variability with the considered mask.In addition, a hint of a possible T-E alignment between the asymmetry axes is found at the level of ∼ 5%. For the analysis, we have implemented an alternative inpainting approach in order to get an accurate reconstruction of the E-modes. More sensitive all-sky CMB polarization data, such as those expected from the future LiteBIRD experiment, are needed to reach a more robust conclusion on the possible existence of deviations from statistical isotropy in the form of a hemispherical power asymmetry.

Ab-initio Investigation of Elastic Properties of Monoclinic ZnAs2 Crystal

Elastic properties of monoclinic ZnAs2 crystal are studied under the PBEsol scheme using the CRYSTAL Program. Independent elastic stiffness coefficients have been computed. Various elastic properties, such as shear modulus, bulk modulus, Young’s modulus and Poisson’s ratio have been analyzed. The directional dependence of the computed Young’s modulus and linear compressibility is studied using ELATE software. Our investigation reveals the finite elastic anisotropy of the monoclinic ZnAs2 crystal.

Intensity and Network Structure of Insomnia Symptoms and the Role of Mental Health During the First Two Waves of the COVID-19 Pandemic.

Insomnia, being a mental disorder, is best conceived as a network of symptoms. With the important increase in insomnia prevalence during the COVID-19 pandemic, our aim was to investigate how the structure of insomnia symptoms in the general population has changed due to the pandemic. We also looked at the directional dependencies of nightmares and of covid- and lockdown-related stress/anxiety and depression in insomnia. 5986 persons replied to our online questionnaire for the first wave and 2843 persons to our second wave questionnaire. Both questionnaires included the Insomnia Severity Index (ISI). Regularized Gaussian Graphical Models (GGM) and Bayesian Directed Acyclic Graphs (DAG) were estimated. The pre- and peri-lockdown networks were equally strongly connected (first wave: S = 0.13, p = 0.39; second wave: S = 0.03, p = 0.67), but differed for the first lockdown regarding only six edges (M = 0.13, p < 0.001) and for the second lockdown only five edges (M = 0.16, p < 0.001). These symptoms all worsened during the lockdowns in comparison to before the pandemic (p < 0.001). The diurnal items of the ISI had the highest predictability and centrality values in the GGMs. Lockdown-related stress/anxiety influenced indirectly nightmares through covid-related stress/anxiety, lockdown-related depressive affect and mental fatigue. These reported feelings of stress/anxiety and depression showed an indirect impact on insomnia symptoms through mental and physical fatigue. Though the lockdown slightly intensified insomnia symptoms, it did not alter their network structure. Despite their differences, both GGMs and DAGs agree that the diurnal symptoms of the ISI, play an essential role in the network structure. Both methods confirm the need for emphasizing the cognitive/affective component in the treatment of insomnia (ie cognitive behavioral therapy).