Numerical Determination Research Articles

Evaluation of Numerical Methods for Predicting the Energy Performance of Windows

Windows are important structural components that determine the energy efficiency of buildings. A significant parameter in windows technology is the overall heat transfer coefficient, U. This paper analyzes the methods of numerical determination of the U-value, including for windows that use passive technologies to improve thermal performance. The analysis was intended to evaluate the heat flux and temperature distribution across glazed surfaces and the accuracy of traditional approaches to the determination of heat loss through window structures. The results were obtained using the heat flux measurement method described in the international standard ISO 9869-1:2014. The paper shows that the non-uniformity of the heat flux density on a window surface can be as high as 60%, which in turn generates an error in the calculations based on stationary heat transfer conditions.

Analysis of Stress Intensity Factor of a Fibre Embedded in a Matrix

The analytical or numerical determination of the stress intensity factor (SIF) in cracked bodies usually assumes the body to be isolated. However, in fibre-reinforced composites, the fibre, which is the main load-carrying component, is embedded in a matrix. To clarify the effect the embedding matrix has on the SIF of the fibre, we propose a 3D computational model of an orthotropic fibre embedded in an isotropic matrix, and compute the SIF using the J-integral method. A parametric analysis based on dimensionless variables explores the effect of the fibre–matrix stiffness ratio as well as the effect of the degree of elastic orthotropy of the fibre. The results show that the SIF is strongly influenced by both factors, and that the matrix reduces the SIF by limiting the crack opening.

Ponding time, hydraulic conductivity, and sorptivity – experimental and numerical determination

Abstract Determination of actual soil sorptivity becomes one of the research preferences in the field of soil management and flash-flood protection. This Note presents an innovative approach to soil sorptivity determination. A single ring infiltration method, along with a simulation of rainfall of constant intensity, was used to measure ponding time t p. Hydraulic conductivity K was approximated from the analysis of the time series of the process of vertical non-steady cumulative infiltration appearing after the ponding time. Based on Philip's infiltration theory, a simple equation was derived in order to calculate sorptivity S from ponding time, rainfall intensity, and saturated hydraulic conductivity. Numerically determined results of S show to closely correspond with theoretical values published in the literature. To the best of our knowledge, this process of numerical determination of K and S has not been published so far. Moreover, unlike the traditional methods, e.g. single or double-ring in filtration experiments, this method provides more precise and representative values of S, verified by ponding time, as the results refer to the original soil sorptivity, not the sorptivity determined after the ponding time (meaning sorptivity of the fully saturated environment) which tends to reach zero. Our assumption was definitely confirmed by field experimental determination of ponding time and selected soil hydrology characteristics.

Combination of Tissue Microarray Profiling and Multiplexed IHC Approaches to Investigate Transport Mechanism of Nucleoside Analog Drug Resistance.

Nucleoside analogs (NAs) are an established class of anticancer agents being used clinically for the treatment of diverse cancers, either as monotherapy or in combination with other established anticancer or pharmacological agents. To date, nearly a dozen anticancer NAs are approved by the FDA, and several novel NAs are being tested in preclinical and clinical trials for future applications. However, improper delivery of NAs into tumor cells because of alterations in expression of one or more drug carrier proteins (e.g., solute carrier (SLC) transporters) within tumor cells or cells surrounding the tumor microenvironment stands as one of the primary reasons for therapeutic drug resistance. The combination of tissue microarray (TMA) and multiplexed immunohistochemistry (IHC) is an advanced, high-throughput approach over conventional IHC that enables researchers to effectively investigate alterations to numerous such chemosensitivity determinants simultaneously in hundreds of tumor tissues derived from patients. In this chapter, taking an example of a TMA from pancreatic cancer patients treated with gemcitabine (a NA chemotherapeutic agent), we describe the step-by-step procedure of performing multiplexed IHC, imaging of TMA slides, and quantification of expression of some relevant markers in these tissue sections as optimized in our laboratory and discuss considerations while designing and carrying out this experiment.

Uncertainty Principle and Numerical Value Determination of the Strong Nuclear Force

Uncertainty Principle and Numerical Value Determination of the Strong Nuclear Force

Numerical and experimental determination of contact heat transfer during orthogonal cutting

During the cutting process, a large part of the mechanical work is converted into heat, which is dissipated to the environment via the chip, the tool and the workpiece in dry machining. The heat flux partition in the cutting zone depends on the contact heat transfer between the workpiece and the tool. In most cutting simulations to date, the contact heat transfer is assumed to be thermal resistance-free contact, which leads to an overestimation of the heat flux into the tool. In this work, a pressure and temperature dependent contact heat transfer model was derived and implemented in the numerical cutting simulation. The model parameters for dry machining of AISI 1045 with carbide tools were calibrated experimentally. The heat distribution determined with the model provided assured accuracy for orthogonal machining with low uncut chip thickness and thus established a basis for the investigation of the process parameters on the tool temperature.

Critical Determinants of the Competitiveness of the Ghanaian Construction Industry

Construction industry’s contribution to the development of nations has been well documented in the literature. Some authors argue that the construction industry offers one of the most significant avenues through which infrastructure is provided for almost every sector of economy. Yet, studies focusing on the development of the construction industry are replete with problems regarding the numerous competitiveness determinants to consider, not only from where and whom to collect the data but also the type and range of data. This study investigates the essential factors influencing the competitiveness of the Ghanaian construction industry (GCI) using Michael Porter’s Diamond Model. Factor analysis revealed four underlying constructs that determine the competitiveness of the GCI. These include industrial resources availability, construction business strategies and project management, stakeholders’ demands and performance and government role and industry development policy. The study highlights that more emphasis should be placed on macro-variables of GCIs at the national level and senior managers in GCI should integrate advanced management processes and techniques in construction business management to improve upon their performances. In addition, the results from the current study may help inform and direct government policies towards repositioning and engendering the competitiveness of the GCI, while providing international construction firms entering the GCI with first-hand information about the performance of the GCI.

Contribution of carbohydrate-related metabolism in Herpesvirus infections

Human herpesviruses are enveloped viruses with double-stranded linear DNA genomes highly prevalent in the human population. These viruses are subdivided into three subfamilies, namely alphaherpesvirinae (herpes simplex virus type 1, HSV-1; herpes simplex virus type 2, HSV-2; and varicella-zoster virus, VZV), betaherpesvirinae (human cytomegalovirus, HCMV; human herpesvirus 6, HHV-6; and human herpesvirus 7, HHV-7) and gammaherpesvirinae (Epstein-Barr virus, EBV; and Kaposi's sarcoma-associated herpesvirus, KSHV). Besides encoding numerous molecular determinants to evade the host antiviral responses, these viruses also modulate cellular metabolic processes to promote their replication. Here, we review and discuss existing studies describing an interplay between carbohydrate metabolism and the replication cycle of herpesviruses, altogether highlighting potentially new molecular targets based on these interactions that could be used to block herpesvirus infections.

Numerical and experimental determination of stress and strain state in a connection lug

Numerical and experimental determination of stress and strain state in a connection lug

Analysis of laser scanning and photogrammetric scanning accuracy on the numerical determination of Head-Related Transfer Functions of a dummy head

Individual Head-Related Transfer Functions (HRTFs) are necessary for the accurate rendering of virtual scenes. However, their acquisition is challenging given the complex pinna shape. Numerical methods can be leveraged to compute HRTFs on meshes originating from precise scans of a subject. Although photogrammetry can be used for the scanning, its inaccuracy might affect the spatial cues of simulated HRTFs. This paper aims to assess the significance of the photogrammetric error affecting a Neumann KU100 dummy head scan. The geometrical differences between the photogrammetric scan and a laser scan are mainly located at the pinna cavities. The computed photogrammetric HRTFs, compared to measured and simulated data using objective and perceptually inspired metrics, show deviation in high frequency spectral features, stemming from the photogrammetric scanning error. This spectral deviation hinders the modelled elevation perception with photogrammetric HRTFs to levels comparable to renderings with nonindividual data. Extracting the photogrammetric geometry at individual ear cavities and merging it to the laser mesh, an assessment of the influence of the inaccuracy at different pinna structures is conducted. Correlation analysis between acoustic and geometrical metrics computed on the results is used to identify the most relevant geometrical metrics in relation to the HRTFs.

Modeling of the thermal regime of a platformless navigation system with thermal stabilization of accelerated warm-up

Currently, platformless inertial navigation systems (IBS) based on fiber optic gyroscopes (FOG) are widely used in modern aviation and space technology. In connection with the high sensitivity of VOG to the influence of temperature changes, ensuring stable thermal modes of operation is an urgent problem. The most important task of increasing the accuracy of system operation is the development of methods of thermal protection and thermostabilization of VOG. The work is devoted to the modeling of the temperature field of the platformless inertial unit (BIB), which is part of the BINS, in order to ensure a minimum temperature difference on the VOG platform with the use of thermal stabilization. The purpose of the work is to simulate the temperature field of the BIB measuring unit and determine the conditions that ensure a minimum of temperature differences on the VOG platform under thermal stabilization conditions. To achieve the goal, the following tasks were solved: creation of a calculation scheme and finite element model of the BIB device, modeling of the effect of changes in external temperatures on the temperature field of the BIB device, numerical determination of temperature gradients at given points of the device. According to the results of numerical modeling, the parameters of the temperature field of the device and the characteristics of the thermal stabilization system were studied. The thermal mode of the device with a thermostabilization system for accelerated heating and reduction of temperature change gradients on VOG sensors with a governing law corresponding to base temperature changes is considered. The temperature gradients at the given points of the device are numerically determined. It was established that the law of thermostabilization should ensure the stability of the temperature field (the smallness of the temperature gradient). The value of the VOG temperature itself does not have a significant effect on the amount of drift. It is advisable to use the thermal stabilization system only to bring the system to the working temperature mode for no more than 30 minutes, and not to use it in the working mode.

Media Visibility Index as a Tool for Measuring the Presence of Political Parties in the Media: Case of Polish Parliamentary Election Campaign in 2019

The problem of media visibility of politicians and political parties is at the heart of the interest of political communication researchers. Theoretical reflections and empirical studies focus on numerous media presence determinants. At the same time, attempts to identify the media visibility of political actors in specific periods, such as the particularly important for democracy period of the election campaign preceding the parliamentary election, are relatively rare. This study is intended to fill that gap. It proposes a simple research tool in the form of a media visibility index, which makes it possible to calculate and compare the visibility of electoral committees in selected media during the election campaign. The tool was used to determine the visibility of electoral committees taking part in the 2019 parliamentary elections in Poland in two TV news services “Wiadomości” and “Fakty”, and three weekly opinion magazines “Newsweek”, “Polityka” and “Sieci”. The data to calculate the index was gathered through manual content analysis of the studied media conducted six weeks before the day of the parliamentary elections.

Experimental and numerical determination of interlayer shear strength of glass fiber-reinforced epoxy composites

This study aims to produce glass fiber composite plates by vacuum infusion method and to determine the interlaminar shear strength (ILSS) under the short beam test. For this purpose, composite plates were produced under the effect of vacuum and temperature by adding glass fiber layers on a flat vacuum table. Short beam tests were carried out on the obtained laminated composite plates and the interlayer shear strength, which is generally characterized by delamination damage, was investigated. In the numerical part, the tests were modeled using the LS-DYNA finite element package program, and the Hashin damage criterion-based material model was used to see the damages that occurred in the composite structure after the tests.

What Firm-Specific and Macroeconomic Determinants of Financial Structure Affect Transport and Storage Companies from Selected European Countries?

A number of indicators can be assessed for a company’s financial health, with indebtedness indicators being one of the important ones. The formation of the financial structure is influenced by a huge number of factors. The subject of this research is the indebtedness of companies in the Transportation and storage industry. The companies come from the V4 countries, Austria, Bulgaria, Slovenia, and Romania, between 2010 and 2018. In total 25,246 companies are analysed according to their size for medium and large companies. The aim of the research is to find out whether profitability, liquidity, asset structure, non-debt tax shield, GDP growth rate, reference interest rate, and inflation rate affect the level of total, long-term and short-term debt. The main finding is that corporate debt is significantly affected (measured by the value of coefficients) by non-corporate determinants and specifically the development of the reference interest rate. However, if we look at the most numerous determinants, it is profitability. Companies in the selected industry should focus primarily on the various forecasts within the external environment of the company and include them in their analyses when financing their activities.

Risk-Based Method for Determining Separation Minima in Unmanned Aircraft Systems

Risk assessment is a key issue in enabling the use of unmanned aircraft systems (UASs) in nonsegregated areas, especially in very low-level airspace and urban areas. The specific operations risk assessment (SORA) methodology represents an important milestone in performing the risk assessments required by aviation safety agencies to UAS operators in specific operations. However, the SORA is a qualitative method used for UASs operating inside a well-bounded operational volume. This paper proposes a quantitative method that can not only be used in a closed volume but also in an airspace shared by several UAS missions and even general aviation. The basis for this is providing a separation volume (a “bubble”) to prevent collisions that is calculated using a risk-based approach. The method consists of setting a target level of safety, which is accomplished using a tradeoff between strategic and tactical mitigations. A probabilistic methodology for performing quantitative risk assessment of strategic and tactical mitigations is provided, and the dependence of the separation distance is carefully analyzed. All factors affecting the separation distance are identified, and their contributions to collision risk are probabilistically estimated. The method takes into account specific factors relating to UASs such as trajectories, separation methods, and performance. As a result, the method allows numerical determination of a separation distance for a given target level of safety and an operational scenario.

ВУЛКАНИЧЕСКИЕ КОМПЛЕКСЫ И ТЕКТОНО-МАГМАТИЧЕСКИЕ ЭТАПЫ ЭВОЛЮЦИИ МАГЕЛЛАНОВЫХ ГОР (ТИХИЙ ОКЕАН). СООБЩЕНИЕ 1: ВУЛКАНИЧЕСКИЕ КОМПЛЕКСЫ

The paper presents original and published data of radioisotope dating of volcanic rocks of the Magellan Seamounts. These data and available geological materials allow us to distinguish five major volcanic complexes of different ages in the guyots of the Magellan Seamounts: 1 — Late Jurassic-Early Cretaceous (earliest Cretaceous); 2 — Early Cretaceous (Apt-Albian); 3 — Late Cretaceous (Late Cenomanian-Turonian- Early Campanian); 4 — Late Cretaceous (Late Campanian-Maastrichian); 5 — Cenozoic. Each of these age complexes corresponds to a specific tectonic-magmatic stage of the evolution of the Magellan Seamounts and characterizes a specific geomorphological space (pedestal, main body, small complicating superimposed structures of the second order). This division is based on numerous isotopic age determinations for 11 guyots obtained by K-Ar and Ar-Ar methods. The tectonic-magmatic evolutionary stages of the Magellan Seamounts correspond, in general, to the periods of tectonic activation for other structures of the Pacific Ocean bed.

Numerical determination of fluid‐to‐particle mass and heat transfer coefficients in packed bed reactors

AbstractA method based on particle‐resolved CFD is built and validated, to calculate the fluid‐to‐particle mass and heat transfer coefficients in packed beds of spheres with different tube‐to‐particle diameter ratios (N) and of various particle shapes with N = 5.23. This method is characterized by considering axial dispersion. The mass and heat transfer coefficients increase by 5%–57% and 9%–63% after considering axial dispersion, indicating axial dispersion should be included in the method. The mass and heat transfer coefficients are reduced as N decreases. The catalyst particles without inner holes show higher mass and heat transfer coefficients than the ones with inner holes, because of unfavorable fluid flow in inner holes. The bed of trilobes has the highest mass and heat transfer coefficients, being 85% and 95% higher than the one of spheres. This work provides a versatile method and some useful guidance for the design of packed bed reactors.

Tabakalı Zeminlerde Tekerlek Temas Gerilmesi ve Deplasman Dağılımlarının Üç Boyutlu Sınır Eleman Yöntemi ile Belirlenmesi

In this study, the Boundary Element Method (BEM) was employed for the numerical determination of the response of a layered half-space. The material behaviour of the soil was assumed to be isotropic and linear elastic. The BEM was used in the Fourier transform space (FTS). The focus of this paper is to determine the stress and deflection distributions of interior points of a layered half-space. To achieve this aim, in this study, a computer program is developed for three-dimensional elastic or visco-elastic problems. The results of stress and deflection distributions in a layered half-space determined using boundary element formulation are presented in figures.

Mathematical modeling and computational outcomes for the thermal oblique stagnation point investigation for non-uniform heat source and nonlinear chemical reactive flow of Maxwell nanofluid

Owing to fine thermal prospective of nanomaterials, different applications have been addressed in nanotechnology and thermal management systems. Multidisciplinary applications of such nanomaterials are commonly observed in nuclear reactors, thermal systems, transportation systems, industrial products cooling, power industry, renewable energy etc. The motivated work aims to predicts improved thermal consequences of Maxwell nanofluid with applications of non-uniform heat source and radiated phenomenon. The heat transfer analysis is assessed by using the Cattaneo-Christov theories. The thermal phenomenon is controlled with interference of slip effects. The flow pattern is based on the oblique stagnation point flow confined by stretched cylinder. The Keller Box numerical determination of problem is worked out with fine accuracy. The physical dynamic of flow parameters is visualized graphically. It is claimed that control of thermal transportation phenomenon is resulted when the slip effects are dominant. The exponential heat source with nonlinear radiated phenomenon is important when enhancement in thermal process needed.

A case study of the Severo-Danilovskoye field on experimental and numerical determination of miscibility parameters when justifying gas injection

Miscibility largely determines the performance of gas injection. Miscible displacement allows achieving maximum effect. The minimum miscibility pressure (MMP) is a key parameter, which is determined when justifying a gas injection project. For the conditions of East Siberian reservoirs, the accuracy of correlation equations is 10-50 %, and A. M. Maklavani, H. M. Sebastian, and M. Dong equations demonstrate the most accurate values. The equation of state matched to the results of routine studies evaluates the MMP with an error of up to 30 %. Additional data from special studies (swell test) increased the estimating accuracy by up to 10 %. An express laboratory method for measuring the miscibility parameter (a method of vanishing interfacial tension) showed high accuracy of MMP estimate. The method also allows describing the process of changing the interfacial tension with increasing pressure or changing the gas composition, and complements the process of adjusting the equation of state when setting up a slim tube experiment.