Basic Conservation Principles Research Articles

Stochastically estimated covariance matrices for independent and cumulative fission yields in the ENDF/B-VIII.0 and JEFF-3.3 evaluations

A Monte-Carlo method for the generation of correlation and covariance matrices for independent and cumulative fission yields has been developed. The method uses a constrained Monte-Carlo resampling structure in order to vary evaluated fission yield libraries in a way that meets basic conservation principles. This results in the generation of correlation/covariance matrices with limited model bias and uncertainty; the matrices are primarily reflective of the evaluated fission yield uncertainties and correlations that arise from the evaluation process. This method has been applied to generate correlation and covariance matrices for all of the fissioning systems of the ENDF/B-VIII.0 and JEFF-3.3 evaluations, marking the first time such matrices have been generated for all of these systems. These covariance matrices have been published online for immediate public use. These correlation and covariance matrices can be used to improve uncertainty estimation in calculations of reactor antineutrino emission rates, decay heat problems, and nuclear forensics.

ИСТОРИЧЕСКИЕ НЕКРОПОЛИ Г. ОМСКА -ОПЫТ ИЗУЧЕНИЯ И СОХРАНЕНИЯ

The present article is devoted to studying history and conservation problems of historical cemeteries in the city of Omsk, taking into account the constantly changing urban environment. In the last ten years archaeological research has uncovered seven new heritage sites, and the location of two other heritage sites has been precised. Four of these nine sites are cemeteries belonging to the 18th - 20th centuries. The present article summarizes our research, and in our conclusion we raise the question of the possibility of conserving such heritage sites. Even though the basic principles of conservation are aligned with the current methodology of field archaeological work, it is possible to encounter problems of ethical nature both from researchers and developers while working with historical necropolises. Despite the fact that the article is based on materials related to the city of Omsk, the problems outlined in it are relevant for any large modern city, since they all tend to grow and modernize. Keywords: western Siberia, Omsk, urban planning, change, historical necropolises, archaeological research, conservation

Article 2

The conservation of stone in the scientific aspect became the subject of research in the nineteenth century, when the foundations of the theory of conservation of monuments, today more widely understood as the protection of cultural her-itage, were laid. Since then, in spite of many projects, publications and even patents, the issue of stone conservation is still open and the research continues. The significance of the issue is evidenced by rich volumes of conference materials from The Inte-rnational Congresses on Deterioration and Conservation of Stone, held every 4 years. The materials from these confe-rences are available on the ISCS-ICOMOS website (http://iscs.icomos.org). The aim of this work is to familiarize the readers with many years of experience of the so-called Polish school of conservation of monuments in the field of conservation of stone monuments. The causes of deterioration, the basic principles of conservation and the methods used in individual stages of conservation and restoration work on stone sculpture and architectural detail will be discussed.

Comparative Study on a Straight and Helical Capillary Tube for CO2 and R22 Refrigerant

Abstract A comparative study has been carried out on the adiabatic straight and helical capillary tube, using a CO2 and R22 refrigerant. The numerical model for CO2 and R22 is developed using the basic principles of conservation of mass, momentum, and energy. The effect of coiling in the helical capillary tube is compared with a straight capillary tube for CO2 and R22 refrigerant. Compared with the straight capillary tube, the percentage reduction in mass flowrate in the helical capillary tube is calculated with a change in coil diameter, tube diameter, and length. As the coil diameter increases from 30 mm to 150 mm, the percentage reduction in mass is from 5.8% to 2.2% in CO2, and 5% to 1.6% in R22. For helical capillary tube with 50 mm coil diameter, as the tube diameter increases from 1 to 1.5 mm, the percentage reduction in mass flowrate with CO2 refrigerant is from 2.65% to 4.96%, however, for R22 it is from 2.43% to 4.24%. Similarly, as the capillary tube length increases from 1.3 m to 1.8 m, the percentage reduction in mass with CO2, with 50 mm coil diameter is 4.44–4.55%. However, the percentage reduction in mass with R22 is 3.71–3.85%. Moreover, compared with the straight capillary tube, the percentage reduction in length in a helical capillary tube with coil diameter 50 mm is 16% for CO2 and 9% for R22 refrigerant.

Influence of geometric and operating parameters on the performance of the helical capillary tube for the R744 refrigerant

This paper reveals the numerical investigation of the helical capillary tube. The study is carried out for an adiabatic, homogenous capillary tube with the R744 refrigerant. The basic principles of conservation of mass, momentum, and energy are used to develop the mathematical model. The results of the present coiled capillary tube model are verified with previously published test results. The refrigerant properties of R744 are employed from CO2PROP. The influence of various geometric parameters of the capillary tube-like tube diameter, roughness, and coil diameter on the performance of the tube been computed. The consequence of the tube diameter on the tube performance is larger than other geometric parameters. As the tube diameter increase by 18%, the mass flow rate increase by nearly 55%. Similarly, as an increment in the coil diameter took place by 10%, the mass flow rate increase by 5%. The negligible change is observed owing to the change in surface roughness. While the surface roughness increases by 18%, the mass increases by 1%. Moreover, the influence of various operating factors is evaluated. A significant variation in the tube and system performance is seen owing to the change in gas cooler temperature. As the gas cooler temperature rises by 5%, the drop in mass flow rate is about 18%. Comparatively, less effect is recorded due to an evaporator temperature. As the evaporator temperature rises by 15%, the mass flow decreases by nearly 11%. The considerable impact is perceived owing to the change in pressure of the gas cooler. As the gas cooler pressure increases by 4%, the mass flow rate increases by nearly 7%. Similarly, the influence of operating and geometric parameters on the coefficient of performance and cooling capacity of the transcritical R744 system is evaluated. For optimum performance of the R744 cycle, the selection of proper gas cooler temperature and gas cooler pressure is a key factor. This work is useful to design the helical capillary tube with R744 refrigerant.

Pumping flow model for couple stress fluids with a propagative membrane contraction

A pumping flow model induced by propagative and non-propagative wall contraction is presented to examine the pumping and flow characteristics. A couple stress fluid model is considered to see the effect of couple stress parameter. An inelastic single membrane is used in upper wall of the channel with rhythmic contraction to produce unidirectional flow which can be applied in many physiological transports. Governing equations are derived using basic conservation principles of mass and momentum. Furthermore scaling analysis is made to introduce the lubrication theory (typical length scale δ=(H/λ)≪1 and low Reynolds number approximation). The influence of the couple stress parameter, propagative shape membrane, and the time variation on axial velocity, volumetric flow rate, local shear stress, pressure gradient, and streamline distribution are evaluated with aid of in-house code in Matlab. The significant stagnation line in the flow streamline with the membrane parameter is computed where the pressure gradient is zero. This study is relevant in the simulation of fluid dynamics of duodenum and intestine and other physiological systems. Novel smart biomimetic pumping devices are relatively easy to engineer using this pumping mechanism.

Flow behavior of spiral capillary tube for CO2 transcritical cycle

A numerical study has been carried out on the spiral capillary tube for the CO2 transcritical cycle. The model is based on the basic principles of conservation of mass, momentum, and energy. The results of this model are validated with earlier published test results. The effect of various geometric parameters like tube diameter, length, roughness, and pitch on the mass flow rate, cooling capacity, and COP has been calculated. The mass flow rate of the tube is mostly influenced by the internal tube diameter, as the diameter increases by 28%, the mass flow increases by 88%. A minor change in mass is observed with a change in pitch and surface roughness, as the pitch increases from 300 to 700 mm, and surface roughness increases by 14%, the mass flow rate and cooling capacity increase only by 2% and 1%, respectively. Similarly, the influence of various operating factors like gas cooler pressure, evaporator temperature, and gas cooler temperature is evaluated. A significant change in mass is observed with the change in gas cooler temperature, as the gas cooler temperature increases by 5%, the mass flow rate, cooling capacity, and COP decrease by 19%, 40%, and 33%, respectively. Relatively less variation in mass flow rate is observed with the change in evaporator temperature. As the evaporator temperature increases by 12%, the mass flow rate decreases by nearly 5.5%, and cooling capacity decreases by 18%. Energy and exergy analyses of a CO2 transcritical system are carried out.

Comparative study on a straight and helical capillary tube for CO2 transcritical system

A comparative study on an adiabatic straight and helical capillary tube employing homogenous flow conditions for a CO2 refrigerant. The numerical model is based on the basic principles of conservation of mass, momentum, and energy. A result of the present model is validated with previously published test results. The properties of CO2 refrigerants are obtained from property code CO2PROP. Compared to the straight capillary tube, the percentage reduction in mass flow rate for various internal diameter, tube length, and coil diameter are evaluated. It is observed that percentage reduction in mass flow rate increases as the coil diameter, tube diameter, and length of helical capillary tube increases. Again comparison between straight and helical tube is done by calculating tube length at same working conditions. Compared to straight capillary, for similar operating and geometric conditions, the percentage reduction in length for coil diameter 50mm is 16.4%, for coil diameter 100mm is 14.2% and for coil diameter 150mm is 13.5%. This comparative study is useful for designing of compact refrigeration system using CO2 as a refrigerant.

Influence of geometric and operating parameters on the flow behavior of the helical capillary tube

This paper reveals numerical study on an adiabatic helical capillary tube employing homogenous and unchoked flow conditions for a CO2 refrigerant. The numerical model is based on the basic principles of conservation of mass, momentum, and energy. A result of the present model is validated with previously published test results. Thermodynamic and transport properties of CO2 refrigerant are obtained from property code CO2PROP which is developed by employing an iterative procedure of derivatives of Helmholtz free energy function. The influence of various geometric parameters like tube diameter, roughness, and coil diameter on the mass flow rate of the capillary tube has been evaluated. The mass flow of the helical capillary tube largely depends on the internal diameter. While the very minor change in mass is observed with change surface roughness. Influence of various operating factors like gas cooler pressure, temperature and evaporator temperature evaluated. A significant change in mass is observed with the change in gas cooler temperature, comparatively less effect is observed with evaporator temperature. For optimum performance of the transcritical CO2 cycle, selection of proper gas cooler temperature, gas cooler pressure is a key factor. This study may be useful for the design of helical capillary tube for CO2.

New analytical solution for stream\u2013aquifer interaction under constant replenishment

In the present paper, approximate analytical solutions for flow in unconfined aquifers with streams are obtained assuming one-dimensional horizontal groundwater flow in homogeneous and isotropic aquifer with recharge effect using variational homotopy perturbation method which is a combination of variational iteration method and homotopy perturbation method. The governing nonlinear Boussinesq equation is obtained by using a basic principle of conservation of mass followed by Dupuit’s assumptions. Sensitivity of the parameters has been analyzed. The obtained approximate analytical solutions are numerically validated. The present analytical method is reliable and can be equally well applied to other nonlinear equations arising in the stream–aquifer interaction problems.

Characterization of the interacting gas-particle dynamic system in cold spray nozzles in dimensional and non-dimensional form

In order to study fundamental particle and gas dynamic behavior in the cold spray process, a simplified model was created assuming all dependent process parameters to vary in the streamwise x-coordinate only. This model resulted in a coupled system of ordinary differential equations describing gas and particle interactions in terms of basic conservation principles for mass, momentum and energy within a converging-diverging nozzle. The system of ordinary differential equations along with a prescribed set of initial conditions for all dependent variables at x = 0, forms an initial value problem which was integrated in the x-direction using a 4th order Runge-Kutta method to determine the velocity and temperature of the gas and particle phases. The numerical solutions from the model were then validated by comparison with steady, axisymmetric, two-dimensional computational models incorporating the relevant PDE's using the CFD software. To obtain additional insight into the dynamic and thermal behavior of the coupled system, applicable scales were chosen to cast the simplified dimensional governing equations in non-dimensional form. One of the significant results of this simplified one-dimensional study is the parameterization that falls out naturally from the scaled equations, thus conferring a more general means to characterize (in non-dimensional terms) the relative gas-particle momentum and energy exchange in higher dimensional problems. From the scaled results it was also discovered that there is no advantage in using lighter, more expensive carrier gases such as helium to accelerate larger, heavier particles, and thus considerable cost savings can result through the use of compressed air.

On the modelling of shallow turbidity flows

In this study we investigate shallow turbidity density currents and underflows from mechanical point of view. We propose a simple hyperbolic model for such flows. On one hand, our model is based on very basic conservation principles. On the other hand, the turbulent nature of the flow is also taken into account through the energy dissipation mechanism. Moreover, the mixing with the pure water along with sediments entrainment and deposition processes are considered, which makes the problem dynamically interesting. One of the main advantages of our model is that it requires the specification of only two modeling parameters - the rate of turbulent dissipation and the rate of the pure water entrainment. Consequently, the resulting model turns out to be very simple and self-consistent. This model is validated against several experimental data and several special classes of solutions (such as travelling, self-similar and steady) are constructed. Unsteady simulations show that some special solutions are realized as asymptotic long time states of dynamic trajectories.

Numerical Limitations of 1D Hydraulic Models Using MIKE11 or HEC-RAS software – Case study of Baraolt River, Romania

MIKE 11 is an advanced hydroinformatic tool, a professional engineering software package for simulation of one-dimensional flows in estuaries, rivers, irrigation systems, channels and other water bodies. MIKE 11 is a 1-dimensional river model. It was developed by DHI Water · Environment · Health, Denmark. The basic computational procedure of HEC-RAS for steady flow is based on the solution of the one-dimensional energy equation. Energy losses are evaluated by friction and contraction / expansion. The momentum equation may be used in situations where the water surface profile is rapidly varied. These situations include hydraulic jumps, hydraulics of bridges, and evaluating profiles at river confluences. For unsteady flow, HEC-RAS solves the full, dynamic, 1-D Saint Venant Equation using an implicit, finite difference method. The unsteady flow equation solver was adapted from Dr. Robert L. Barkau’s UNET package. Fluid motion is controlled by the basic principles of conservation of mass, energy and momentum, which form the basis of fluid mechanics and hydraulic engineering. Complex flow situations must be solved using empirical approximations and numerical models, which are based on derivations of the basic principles (backwater equation, Navier-Stokes equation etc.). All numerical models are required to make some form of approximation to solve these principles, and consequently all have their limitations. The study of hydraulics and fluid mechanics is founded on the three basic principles of conservation of mass, energy and momentum. Real-life situations are frequently too complex to solve without the aid of numerical models. There is a tendency among some engineers to discard the basic principles taught at university and blindly assume that the results produced by the model are correct. Regardless of the complexity of models and despite the claims of their developers, all numerical models are required to make approximations. These may be related to geometric limitations, numerical simplification, or the use of empirical correlations. Some are obvious: one-dimensional models must average properties over the two remaining directions. It is the less obvious and poorly advertised approximations that pose the greatest threat to the novice user. Some of these, such as the inability of one-dimensional unsteady models to simulate supercritical flow can cause significant inaccuracy in the model predictions.

Concurrent reconciliation of chemical and mineral assays for mineral processing circuits

The steady-state data reconciliation of mineral processing plants has traditionally depended on chemical assays of samples collected from various streams in the plant. In some cases, additional information in the form of size assays and size-wise chemical assays have been employed to improve the reconciliation problem. Reconciliation algorithms, in addition to making the measured data consistent with the basic conservation principles, also help in predicting the material flow rates in different streams. This information helps the process engineer to identify and troubleshoot problem areas, and further use it to optimize the plant's performance. If all the minerals present in the ore system are known (established through X-Ray Diffraction), the chemical formulae of the minerals provide the relationship between the chemical assays and mineral composition. In this communication, first we propose an approach to estimate the mineral composition from the measured chemical assays for a given sample or stream. It is then extended to a plant-wide concurrent data reconciliation methodology, involving both the chemical assays and mineral composition. This concurrent data reconciliation procedure provides estimates of mineral composition around the plant even when mineral composition measurements are not available. This additional information will help the plant engineers to track and improve their plant's behavior more intuitively. When mineral compositions are measured (for example, through QEMSCAN) they can be reconciled along with chemical assays. The methodology is demonstrated with data from batch and semi-batch laboratory studies on selective dispersion-flocculation of iron ore slimes.

Effect of the cosolutes trehalose and methanol on the equilibrium and phase-transition properties of glycerol-monopalmitate lipid bilayers investigated using molecular dynamics simulations.

The influence of the cosolutes trehalose and methanol on the structural, dynamic and thermodynamic properties of a glycerol-1-monopalmitate (GMP) bilayer and on its main transition temperature [Formula: see text] is investigated using atomistic molecular dynamics simulations (600 ns) of a GMP bilayer patch (2×8×8 lipids) at different temperatures in the range of 302 to 338 K and considering three different cosolute concentrations. Depending on the environment and temperature, these simulations present no or a single GL[Formula: see text]LC, LC[Formula: see text]GL or LC[Formula: see text]ID transition, where LC, GL and ID are the liquid crystal, gel and interdigitated phases, respectively. The trehalose molecules form a coating layer at the bilayer surface, promote the hydrogen-bonded bridging of the lipid headgroups, preserve the interaction of the headgroups with trapped water and induce a slight lateral expansion of the bilayer in the LC phase, observations that may have implications for the phenomenon of anhydrobiosis. However, this cosolute does not affect [Formula: see text] and its dependence on hydration in the concentration range considered. On the other hand, methanol molecules intercalate between the lipid headgroups, promote a lateral expansion of the bilayer in the LC phase and induce a concentration dependent decrease of [Formula: see text], observations that may have implications for the phenomenon of anesthesia. The occurrence of an ID phase in the presence of this cosolute may be viewed as an extreme consequence of lateral expansion. The analysis of the simulations also suggests the existence of two basic conservation principles: (1) the hydrogen-bond saturation principle rests on the observation that for all species present in the different systems, the total numbers of hydrogen-bonds per molecule is essentially constant, the only factor of variability being their distribution among different partners; (2) the densest packing principle rests on the observation that the effective volume per methylene group in the interior of the bilayer is only weakly sensitive to the environment, with values comparable to those for liquid (LC) and solid (ID) alkanes, or intermediate (GL).

Research on Temperature Distribution for Tubing Liquid with Hot Natural Gas Injected Annulus Using Gas Lift

In light of the difficulty including the complicacy of heat transfer process with hot natural gas injected in gas lift annulus, regular temperature prediction methods are commonly used to consider the tubing fluid temperature for the heat transfer from tubing to annulus, actually the tubing fluid will not be the external heat transfer but it will be heated by annulus when the gas temperature in annulus is higher than the tubing fluid temperature, as well as especially the prediction of tubing wellhead temperature in terms of fluid temperature distribution traits in annulus and tubing, regular temperature prediction methods manifest limitation due to their applicability. Based on the fairly comprehensive tubing fluid temperature distribution prediction model with consideration of Thomson effect and such factors as kinetic energy, annular convection heat transfer and phase change etc. developed by the predecessors, and according to the basic principle of conservation of energy and heat transfer, the actual heat transfer process with hot natural gas injected in gas lift annulus was considered as a plus in this paper. The models for actual heat transfer and tubing fluid modified temperature prediction were established and eventually, the models were verified via multiple field tests. The reliability, capable of satisfying the requirements of engineering precision, in terms of temperature distribution of model prediction was proved.

Wood Construction System of Traditional Edirne Houses

Architecture heritage is one of the most considerable items that create the identity of the city. Architecture heritage transmits to following generation with its original form and special features are the basic principle of conservation. The most characteristic factor for continuity is fixed building materials and building technologies. Through the study; it is analyzed those wood constructions, usage of materials and methods of construction were built in the late 19 century and early 20 century and also hardly accessible in Edirne where the societies lived together with their different national and religious values (Grek, Bulgarian, Armenian, Jewish...). It is intended to secure this cultural heritage with its methods of construction and all details against the danger of extinction and to transmit following generations. Keywords: Wood Construction System, Tradional House, Sustainable Conservation

Devolatilization‐induced pressure build‐up: Implications for reaction front movement and breccia pipe formation

AbstractGeneration of fluids during metamorphism can significantly influence the fluid overpressure, and thus the fluid flow in metamorphic terrains. There is currently a large focus on developing numerical reactive transport models, and with it follows the need for analytical solutions to ensure correct numerical implementation. In this study, we derive both analytical and numerical solutions to reaction‐induced fluid overpressure, coupled to temperature and fluid flow out of the reacting front. All equations are derived from basic principles of conservation of mass, energy and momentum. We focus on contact metamorphism, where devolatilization reactions are particularly important owing to high thermal fluxes allowing large volumes of fluids to be rapidly generated. The analytical solutions reveal three key factors involved in the pressure build‐up: (i) The efficiency of the devolatilizing reaction front (pressure build‐up) relative to fluid flow (pressure relaxation), (ii) the reaction temperature relative to the available heat in the system and (iii) the feedback of overpressure on the reaction temperature as a function of the Clapeyron slope. Finally, we apply the model to two geological case scenarios. In the first case, we investigate the influence of fluid overpressure on the movement of the reaction front and show that it can slow down significantly and may even be terminated owing to increased effective reaction temperature. In the second case, the model is applied to constrain the conditions for fracturing and inferred breccia pipe formation in organic‐rich shales owing to methane generation in the contact aureole.

Experimental, numerical and analytical modelling of a newly developed rockfall protective cable-net structure

Abstract. An innovative configuration of pocket-type rockfall protective cable-net structure, known as Long-span Pocket-type Rock-net (LPR), has been developed in Japan. The global performance of the proposed system was initially checked by the experimental (full-scale) modelling. Given the various limitations of the physical experiments, particularly for the parametric study to have a detailed understanding of the newly developed system, a reliable and simplified method of numerical modelling is felt necessary. Again, given the sophistication involved with the method of numerical simulation, a yet simplified modelling approach may prove more effective. On top of this background, this paper presents a three-tier modelling of a design of LPR. After physical modelling, which has revealed that the displacement response may be taken more vital for LPR performance, Finite Element based numerical modelling is presented. The programme LS-DYNA is used and the models are calibrated and verified with the element- and structure-level experiments. Finally, a simple analytical modelling consisting of the equivalently linear and elastic, lumped-mass, single-degree-of-freedom system, capable of predicting the global displacement response, is proposed based on the basic principles of conservation of linear momentum and energy. The model is back-calculated and modified from the analyses of the verified numerical model.

Modelling on the effect of diffusive and convective substrate transport for biofilm

A one-dimensional biofilm model was developed based on the basic principle of conservation of mass. Three simple, generic processes were combined in the model which includes microbial growth, diffusive and convective mass transport. The final model could generate a quantitative description of the relationship between the microbial growth and the consumption of substrate (oxygen) within the fixed biofilm thickness. Mass transfer resistance contributes large influence on the substrates and microbial concentration across the biofilm thickness due to the effect of biofilm structure.