Simple Diagram Research Articles

Quantitative assessing of crystal field, nephelauxetic, and Stokes shift effects on the blue luminescence of Eu2+ ions incorporated in ZnS films

A quantitative study of the crystal field, nephelauxetic, and Stokes shift effects on the 5d → 4 f levels of Eu2+ ions incorporated in ZnS films is presented. The magnitude of the crystal effect was calculated using the simplest point charge model to express the crystal field splitting of Eu2+ 5d orbitals surrounded by four S2− ligands in tetrahedral coordination symmetry. The shift of the centroid of the 5d levels by nephelauxetic effect was analyzed using a model that involves the polarizability of the anion ligands, similar to that used to investigate this effect for Ce3+ in many inorganic compounds. The Stokes shift was evaluated according to the Frank-Condon principle, under the idealized situation where the Stokes shift and the emission bandwidth can be expressed in terms of the Huang-Rhys parameter. We found that the redshift of the 5d → 4 f transition for the free Eu2+ ion, due to crystal field splitting was half of the redshift due to the nephelauxetic effect. This result is consistent with the large size, large polarizability, and low electronegativity of the sulfide ions. We also found a relatively large Stokes shift which can be attributed to the autoionization of the 5d electrons to the conduction band levels. The total redshift of the 5d and 4 f energy levels with respect to the 5d and 4 f energy gap for a free Eu2+ in vacuum fits quite well with the blue luminescence peaked at 2.73 eV for Eu2+ ions incorporated in the ZnS films. Based on the experimental results and the calculations for the crystal field splitting, nephelauxetic, and Stokes shift effects, we also propose a simplified energy band and levels diagram which helps to explain the excitation-emission mechanisms of the blue luminescence of the Eu2+ ions incorporated in the ZnS films.

Towards an evidence-based out-patient care pathway for children and young people with avoidant restrictive food intake disorder

Despite growing research and clinical interest in avoidant restrictive food intake disorder (ARFID), robust, evidence-based guidance on optimal treatment interventions, appropriate clinic structures, and modes of service delivery remain absent. Current consensus recommendations include a multi-disciplinary, multi-modal approach to assessment and treatment, with out-patient care being appropriate for the majority of patients, yet to date there is no clear guidance on how this might best be organised or implemented. This lack of guidance is due to a number of factors, that include the time required to conduct the necessary controlled trials and other well-designed investigations and for the subsequent body of research evidence to build. Lack of specific treatment guidance may also be related to the heterogeneous nature of ARFID clinical presentations potentially limiting the likelihood of uniform recommendations. This situation presents a challenge for clinicians required to engage in evidence-based practice, and for health care planners, providers, and policy makers. We describe here a proposed evidence-informed framework for care, subjected to preliminary testing and currently in use in an out-patient eating disorders service for children and young people aged 2–17 years. The use of the simplified care pathway diagram is illustrated with three case examples, and intended to serve as a possible model for further testing in a range of settings. In the face of ongoing uncertainty and inconsistency in the clinical management of ARFID, our intention is to share our experience in the form of an evidence-informed, trialled approach to structuring and providing intervention for this patient population.

Electrochemistry of the NaI-AlBr3 Molten Salt System: A Redox-Active, Low-Temperature Molten Salt Electrolyte

NaI-AlBr3 is a very appealing low melting temperature (<100 °C), salt system for use as an electrochemically-active electrolyte. This system was investigated for its electrochemical and physical properties with focus to energy storage considerations. A simple phase diagram was generated; at >100 °C, lower NaI concentrations had two partially miscible liquid phases, while higher NaI concentrations had solid particles. Considering the fully molten regime, electrical conductivities were evaluated over 5–25 mol% NaI and 110 °C–140 °C. Conductivities of 6.8–38.9 mS cm−1 were observed, increasing with temperature and NaI concentration. Effective diffusion coefficients of the I−/I3 − redox species were found to decrease with both increasing NaI concentration and increasing applied potential. Regardless, oxidation current density at 3.6 V vs Na/Na+ was observed to increase with increasing NaI concentration over 5–25 mol%. Finally, the critical interface between the molten salt electrolyte and electrode materials was found to significantly affect reaction kinetics. When carbon was used instead of tungsten, an adsorbed species, most likely I2, blocked surface sites and significantly decreased current densities at high potentials. This study shows the NaI-AlBr3 system offers an attractive, low-temperature molten salt electrolyte that could be useful to many applied systems, though composition and electrode material must be considered.

Motility-induced clustering and meso-scale turbulence in active polar fluids

Meso-scale turbulence was originally observed experimentally in various suspensions of swimming bacteria, as well as in the collective motion of active colloids. The corresponding large scale dynamical patterns were reproduced in a simple model of a polar fluid, assuming a constant density of active particles. Recent, more detailed studies in a variety of experimental realizations of active polar fluids revealed additional interesting aspects, such as anomalous velocity statistics and clustering phenomena. Those phenomena cannot be explained by currently available models for active polar fluids. Herein, we extend the continuum model suggested by Dunkel et al to include density variations and a local feedback between the local density and self-propulsion speed of the active polar particles. If the velocity decreases strong enough with the density, a linear stability analysis of the resulting model shows that, in addition to the short-wavelength instability of the original model, a long-wavelength instability occurs. This is typically observed for high densities of polar active particles and is analogous to the well-known phenomenon of motility-induced phase separation (MIPS) in scalar active matter. We determine a simple phase diagram indicating the linear instabilities and perform systematic numerical simulations for the various regions in the corresponding parameter space. The interplay between the well understood short-range instability (leading to meso-scale turbulence) and the long-range instability (associated with MIPS) leads to interesting dynamics and novel phenomena concerning nucleation and coarsening processes. Our simulation results display a rich variety of novel patterns, including phase separation into domains with dynamically changing irregularly shaped boundaries. Anomalous velocity statistics are observed in all phases where the system segregates into regions of high and low densities. This offers a simple explanation for their occurrence in recent experiments with bacterial suspensions.

Predicting Damage to Hop Cones by Tetranychus urticae (Acari: Tetranychidae).

Twospotted spider mite (Tetranychus urticae Koch) is a cosmopolitan pest of numerous plants, including hop (Humulus lupulus L.). The most costly damage from the pest on hop results from infestation of cones, which are the harvested product, which can render crops unsalable if cones become discolored. We analyzed 14 yr of historical data from 312 individual experimental plots in western Oregon to identify risk factors associated with visual damage to hop cones from T. urticae. Logistic regression models were fit to estimate the probability of cone damage. The most predictive model was based on T. urticae-days during mid-July to harvest, which correctly predicted occurrence and nonoccurrence of cone damage in 91 and 93% of data sets, respectively, based on Youden's index. A second model based on the ratio of T. urticae to predatory arthropods late in the season correctly predicted cone damage in 92% of data sets and nonoccurrence of damage in 77% of data sets. The model based on T. urticae abundance performed similarly when validated in 23 commercial hop yards, whereas the model based on the predator:prey ratio was relatively conservative and yielded false-positive predictions in 11 of the 23 yards. Antecedents of these risk factors were explored and quantified by structural equation modeling. A simple path diagram was constructed that conceptualizes T. urticae invasion of hop cones as dependent on prior density of the pest on leaves in early spring and summer, which in turn influences the development of predatory arthropods that mediate late-season density of the pest. In summary, the biological insights and models developed here provide guidance to pest managers on the likelihood of visual cone damage from T. urticae that can inform late-season management based on both abundance of the pest and its important predators. This is critically important because a formal economic threshold for T. urticae on hop does not exist and current management efforts may be mistimed to influence the pest when crop damage is most probable. More broadly, this research suggests that current management practices that target T. urticae early in the season may in fact predispose yards to later outbreaks of the pest.

Consideration to the mean stress based line method for estimating the notch fatigue limit

To consider a mechanistic explanation of the mean stress based line method (called LM) for estimating the notch fatigue limit, the limit values predicted by the LM are investigated from both the energy condition required to create fractured surfaces and the crack propagation condition of the linear elastic fracture mechanism.Based on the energy condition, an energy release criterion (ERC), was introduced to estimate the notch fatigue limit of Δσnp for crack propagation. It is found that Δσn|ERC,1.58L≅Δσn|LM,2L holds for all the investigated notches. Here, Δσn|ERC,1.58L denotes the predicted value by the ERC with the intrinsic crack length lc=1.58L, and Δσn|LM,2L denotes the predicted value by the LM with the characteristic distance dLM=2L (L is the El Haddad’s material characteristic length). The validity of the LM in predicting the fatigue limit of Δσnp based on stress condition was demonstrated by the correspondence relation between the average stress and the energy release in the relevant zone.Also, the growth of small cracks near the notch root is investigated using the R-curve approach. It is found that, as a universal criterion applicable to various notch root radiuses ρ, Δσn|LM,2L gives a critical condition for crack to overcome the typical resistance force represented by the simplified Kitagawa-Takahashi diagram, the values of which is denoted by ΔKth(l)|Kitagawa here. However, to each specified notch root radius ρ,Δσn|LM,2L may be a conservative solution, and theoretically Δσnp⩽Δσn|LM,2L holds. The reason is that: (1) most of the curves of crack driving force at a nominal stress of Δσn|LM,2L are above the resistance curve of ΔKth(l)|Kitagawa; (2) the actual resistance curve of the material is generally below the resistance curve of ΔKth(l)|Kitagawa.

Structure evolution and tunable magneto‐optical multifunctional property study of novel Ca18K3Sc1‐xSmx(PO4)14 phosphors

AbstractThe optical‐magnetic multifunctional materials are of great importance owing to their potential applications in intersect discipline fields. However, the multifunctional materials with satisfied optical and magnetic property are limited, and the modulation mechanism of their magneto‐optical property related to their structure feature is ambiguous. Here, a new multifunctional solid solution phosphors Ca18K3Sc1‐xSmx(PO4)14 (0 ≤ x ≤ 1) are designed based on composition engineering and are successfully synthesized. The detailed structure feature including the structural evolution of the crystallographic parameters and local lattice environment as well as polyhedral distortion behavior are investigated through X‐ray diffraction Rietveld structure refinement for Ca18K3Sc1‐xSmx(PO4)14 in the full range (0 ≤ x ≤ 1). The photoluminescence spectra indicate that Ca18K3Sc1‐xSmx(PO4)14 (0 ≤ x ≤ 1) can emit intense orange‐red emission (IQE~42.6%) under ultraviolet light excitation ascribed to the4G5/2 ‐6H7/2 transition of Sm3+ ions. The structure modulated luminescence behavior, for example, the tunable emission ratio of I648/I565, high quenching content, and electric multipole interaction mechanism are studied. The versatile phosphors can exhibit tunable orange‐red cathodoluminescence emission along with increasing the accelerating voltage. The electron transition mechanism of the photoluminescence and cathodoluminescence behavior is further discussed through a simple schematic diagram. Moreover, Ca18K3Sc1‐xSmx(PO4)14 (0 ≤ x ≤ 1) shows a ferromagnetic behavior with controllable magnetization and coercive field. Finally, the impact of Fe ions on the photoluminescence and magnetic property of Ca18K3Sc1‐yFey(PO4)14: 0.4Sm3+ (0 ≤ y ≤ 0.05 and y = 1) phosphors are investigated. The current research can provide some ideas and mechanism to design and investigate more novel magneto‐optical muntifunctional materials for versatile applications in intersect disciplines.

Rationality is decidable for nearly Euclidean Thurston maps

Nearly Euclidean Thurston (NET) maps are described by simple diagrams which admit a natural notion of size. Given a size bound C, there are finitely many diagrams of size at most C. Given a NET map F presented by a diagram of size at most C, the problem of determining whether F is equivalent to a rational function is, in theory, a finite computation. We give bounds for the size of this computation in terms of C and one other natural geometric quantity. This result partially explains the observed effectiveness of the computer program NETmap in deciding rationality.

Theory of 3F4D Universe (Beyond Standard Model of Particle Physics)

In this theory, “mass is equivalent to length of imaginary straight line segment” and “direction to imaginary line segment is intrinsic property of that particle which is Equivalent to its intrinsic spin”. With this concept, all fundamental particles, fermions and bosons are described as quanta imaginary string particles with a definite direction. For e.g. unidirectional imaginary straight line with fixed length are massive spin 1/2 fermions; while unidirectional imaginary quanta curved lines are massless spin 1 bosons. Thus, it gives co-relation between massless (curved imaginary line) and spin = 1 properties of boson as proved in QED theory. All fundamental particles of standard model and beyond standard model are arranged in one simple diagram in 3 folds (bottom fold, middle upper and lower folds and top fold) and are projected in 4th Imaginary Dimension in order of decreased in Mass from TeV to approx. 0 eV. This theory is beyond standard model because it predicts new fundamental particles viz. dark matter (spin = 0 massive boson) along with gravitons (spin = 2, massless bosons); 4th pair of neutrinos, vertical massless boson (VMB) particles and tri-axis massive boson (spin = 0) particle. The discovery of these new particles will act as solid proof to this theory. With this 3F4D representation of the universe at an atomic and sub-atomic level, it solves lots of current problems of SM of particle physics like matter-antimatter asymmetry, origin of mass of hadrons like protons, origin of mass and L.H. nature for neutrinos, wave-particle duality of particles, etc. giving true insight of fundamental particles. With proving that, dark matter is not a quanta particle, rather it is a single entity and spreads/expands throughout the universe in the form of “web of spider”, it shows space-time is not empty, but it is filled with Continuous lines of Dark Matter and we, materialistic massive objects are floating/sailing w.r.t. current of this vast ocean. Correlation of its continuity with time gives new a definition to time: “Time is neither Illusion nor 4th Dimension, but, it represents Continuous Flow of Single Entity, Dark Matter”. Space-time is not Empty and is filled with massive dark matter, hence, we have to add more terms to newtonian gravitational equation to account for gravitational strength of mass of surrounding dark matter which represents curvature of space-time in terms of Increase in its mass-density w.r.t. to mass-density of flat universe. Finally, using an empirical formula (h = k*c*Q; k = boltzmann’s constant = mass in TeV range) and inverse relation of mass-density of DM with age of the universe (H2 = Constant&#8226G&#8226Mass-Density of DM); Unification of Gravity at TeV is achieved without consideration of “Gravitational Constant, G”, hence, Planck’s Scale is not required.

ST-BFL: A Structured Transparency Empowered Cross-Silo Federated Learning on the Blockchain Framework

Federated Learning (FL) relies on on-device training to avoid the migration of devices’ data to a centralized server to address privacy leakage. Moreover, FL is feasible for scenarios (e.g., autonomous cars) where an enormous amount of data is generated every day. Transferring only local model updates in the case of FL is highly communication-efficient compared to transferring all data in the case of centralized machine learning (ML). Although FL offers many advantages, it also has some challenges. A malicious aggregation server can infer device information via local model updates. Another downside of FL is the centralized aggregation server that can malfunction due to an attack or physical damage. To address these issues, we propose a novel Structured Transparency empowered cross-silo Federated Learning on the Blockchain (ST-BFL) framework. In ST-BFL, homomorphic encryption, FL-aggregators, FL-verifiers, and smart contract are employed, which satisfy various structured transparency components, such as input privacy, output privacy, output verification, and flow governance. We present the framework architecture, algorithms, and sequence diagram of our ST-BFL framework to show how different entities interact in ST-BFL for the FL process. We also present a simplified class diagram of ST-BFL’s smart contract for an FL task. Finally, we perform a simulation to analyze our framework from the perspective of aggregation time, accuracy, and storage size. The qualitative and quantitative evaluation shows that ST-BFL has the same accuracy as traditional FL. However, ST-BFL provides input privacy, output privacy, input verification, output verification, and flow governance at the expense of relatively higher computation and communication costs than traditional FL.

Criterion for elastoplastic failure of bimetallic plate with edge crack of transverse shear at the boundary of the materials joint

The initiation of a transverse shear edge crack in elastoplastic materials with the limiting strain is considered. The crack propagation criterion is formulated using a modified Leonov-Panasyuk-Dugdale model using the additional parameter - the width of the plasticity zone. The coupled quasi-brittle fracture criterion for mode II cracks in an elastoplastic material is formulated under conditions of small-scale yield in the presence of a singular feature of the stress field in the vicinity of the crack tip. The coupled fracture criterion includes the deformation criterion, which is formulated at the crack tip, as well as the force criterion, which is formulated at the model crack tip. The lengths of the initial and model cracks differ by the length of the prefracture zone. The sequential analysis of the possibility of applying the proposed fracture criterion in determining the critical loads for solids containing edge cracks of transverse shear at the interface of different media is performed. Quasi-brittle fracture diagrams are constructed for a composite plate with an edge crack under plane strain and plane stress conditions. he analysis of the parameters included in the proposed model of quasi-brittle fracture is carried out. The model parameters are proposed to be selected by approximation of simple shear diagram and critical stress intensity factor. The critical loads were found numerically for the quasi-ductile and ductile fracture types. The finite element method is used to solve the problem of drawing out a reinforcing layer from a metal composite under quasi-static loading. The process of propagation of plastic zones in the vicinity of the crack tip is described consistently. It is shown that the shapes of the constructed plastic zones differ significantly from the well-known classical concepts.

A New Model to Evaluate Groundwater Vulnerability that Uses a Hybrid AHP-GIS Approach

ABSTRACT Parameters like aquifer depth, aquifer replenishment rate, aquifer medium, soil medium, percolation medium, and the coefficient of permeability are considered during the preparation of a groundwater vulnerability diagram. The analytic hierarchy process is used for evaluation, and expert scoring is used to analyze and establish the judgment matrix, and then new weights have been computed for each DRASTIC parameter, such that some subjectivity can be reduced to some extent and the weight value tends to be reasonable. Various spatially referenced digital data layers are overlaid to analyse with the partition diagram in GIS spatial analysis and a comprehensive simple and straight diagram is drawn. The study area is a plain of Naiman Banner, Inner Mongolia China, and covers an area of approximately 10,700km2. The areas of lower vulnerability are mainly located in the south. Slightly higher vulnerability areas are mainly located in the north, and the others have medium vulnerability.

General model of hydropneumatic suspension for the grain combine harvester adapter

The paper presents the hydropneumatic suspension mathematical and simulation model development results for the grain combine harvester adapter. The urgency of the work in connection with the hydropneumatic suspensions spread and the need to increase the system efficiency for field relief copying has been substantiated. A computational model of a hydropneumatic suspension including hydraulic cylinders and hydropneumatic shock absorbers connected in parallel to them, including chokes and gas springs has been presented. A system of equations for the hydraulic cylinder piston motion, depending on the hydropneumatic suspension parameters and the number of the connected hydropneumatic shock absorbers has been presented. On the assumption basis, a simplified diagram of the adapter hydropneumatic suspension with back pressure and the corresponding equation system for determining the hydraulic cylinder piston movement have been drawn up. The model includes changing the parameters of external influence on the system, as well as the hydropneumatic accumulator presetting parameters. To assess the developed model’s performance, its simulation model, which was integrated into the well-known simulation model of the grain combine harvester movement, has been compiled. The modeling results of the combine movement on the field with real geometric evenness parameters have been presented. Based on the simulation results, an oscillogram of the hydraulic cylinder piston movement has been shown, depending on the hydropneumatic accumulators’ settings. Conclusions and directions for further research in this area have been presented.

Numerical analysis of stability of an axially-compressed i-beam rod subjected to constrained torsion

Introduction. Today thin-walled structures are widely used in the construction industry. The analysis of their rigidity, strength and stability is a relevant task which is of particular practical interest. The article addresses a method for the numerical analysis of stability of an axially-compressed i-beam rod subjected to the axial force and the bimoment. An axially compressed i-beam rod is the subject of the study. Materials and methods. Femap with NX Nastran were chosen as the analysis toolkit. Axially compressed cantilever steel rods having i-beam profiles and different flexibility values were analyzed under the action of the bimoment. The steel class is C245. Analytical data were applied within the framework of the Euler method and the standard method of analysis pursuant to Construction Regulations 16.13330 to determine the numerical analysis method. Results. The results of numerical calculations are presented in geometrically and physically nonlinear settings. The results of numerical calculations of thin-walled open-section rods, exposed to the axial force and the bimoment, are compared with the results of analytical calculations. Conclusions. Given the results of numerical calculations, obtained in geometrically and physically nonlinear settings, recommendations for the choice of a variable density FEM model are provided. The convergence of results is estimated for different diagrams describing the steel behavior. The bearing capacity of compressed cantilever rods, exposed to the bimoment, is estimated for the studied flexibility values beyond the elastic limit. A simplified diagram, describing the steel behaviour pursuant to Construction regulations 16.13330, governing the design of steel structures, is recommended to ensure the due regard for the elastoplastic behaviour of steel. The numerical analysis method, developed for axially-compressed rods, is to be applied to axially-compressed thin-walled open-section rods. National Research Moscow State University is planning to conduct a series of experiments to test the behaviour of axially-compressed i-beams exposed to the bimoment and the axial force. Cantilever i-beams 10B1 will be used in experimental testing.

A simple band model for ultraviolet induced ambipolarity in single SnO2 nanowire devices

Single Tin Dioxide nanowire (SnO 2 NW) field-effect-transistors (FET) devices have been a great candidate to build electronic circuits, as chemical and physical sensors and study low dimensional properties and related effects. Ambipolarity is one of those effects that may direct its use for specific purposes, where a controllable separated unipolar mode can be achieved in one single device. SnO 2 NWs grown by the VLS method were used for single NW devices fabrication by direct photolithography using the simple back-gate FET architecture. Single SnO 2 NWFET's transport properties were explored, where on/off ratio, mobility and carrier density parameters were extracted, resulting in values around 10 5 , lower than 0.1 cm 2 /V and in the order of 10 19 /cm 3 , respectively. When under ultraviolet (UV) light, all devices presented UV induced ambipolary effect, where on/off states ratio with values of the same order were obtained and ranged from 1.12 to about 19.34. A simple band model was then proposed to explain such behavior. • Ambipolarity allows a controllable separated unipolar mode in FET devices. • Back-gated single n-type SnO2 NWFET showed light induced ambipolarity conduction. • Simple band diagram model fully explains the ambipolarity behavior.

Single resonator microwave device for monitoring the complex dielectric constant of liquid fuels and lubricants

A simplified structural diagram of a single-cavity microwave dielectric meter designed to control the complex permittivity of liquid fuels and lubricants is presented. The structural diagram of the microwave sensor of the dielectrometer, made in the form of a parallelepiped, inside which waveguide paths, a resonator, controlled and reference generators, mixing and detector diodes and attenuators is considered. A general view of the lower part of the microwave sensor housing is given.&#x0D; The technique of initial tuning of the microwave sensor is considered, during which the initial frequencies of the controlled and reference oscillators are set and the range of electronic frequency tuning of the frequency of the controlled generator is determined.&#x0D; A method for calibrating a dielectrometer with an empty cuvette is presented. This method makes it possible to determine the suitability of the cuvette for its use in measuring the complex dielectric constant of samples of fuels and lubricants, and to exclude the influence of the dispersion of the dielectric constant of the material of the cuvette on the results of measuring the complex dielectric constant of fuels and lubricants.&#x0D; The technique of studying the parameters of samples of fuels and lubricants is considered, based on which the measurement data are presented on a complex plane for analyzing the results obtained.&#x0D; A technique for studying the difference between a fuel and lubricant sample and its standard is presented, which includes measuring the parameters of an empty cell, measuring the real and imaginary components of the complex dielectric constant of the fuel and lubricant sample and its standard, and analyzing the differences between their real and imaginary components on a complex plane.

Analysis of Processes Mechanized Oil Mining with the Methods Theory of Electrical Circuits

The authors investigate the problems of the development of the oil and gas complex at the last stage of operation, when oil is extracted by lifting. The main methods of lifting employed in the Russian Federation and the USA are described. A particular focus is placed on large water cuts at this stage of oil production. Literature on the issue under investigation is reviewed and the problem is set to analyze and construct models of oil production processes at the stage of well operation by lifting methods using network analysis (electrical circuits) in order to rationally manage all processes comprehensively. A typical flow chart of the oil production process by lifting methods is described. Technological processes of oil production are compared to processes in electric circuits. Thus the process of pumping purified formation water into injection wells by means of block cluster pumping units is similar to the process of recharging a battery using an electric power generator. The process of filling a production well with gas-liquid mixture displaced from the formation under pressure of injection wells is similar to the process of charging a capacitor from a battery, the process of lifting liquid from production wells using production pumps — to the process of discharging a capacitor on an active load. The simplified electrical diagram of a typical flow chart of oil production processes at this stage is given. Based on the given equivalent electrical circuit of technological processes, according to the laws of theoretical electrical engineering, models of the battery charging, capacitor charging and discharging processes are built. The table of correspondence of the parameters of technological and electrical circuits is presented on the basis of which the authors propose simplified models of the processes of pumping purified formation water into injection wells using unit cluster pumping stations, of filling a production well under pressure of the injection well, lifting liquid from production wells by means of suction pumps and conditions under which various operating modes of lifting processes are achieved.

Blood group systems

Blood group systems

Stochastic model of oxygen adsorption

The authors propose a microscopic stochastic model of the process of oxygen adsorption on the surface of a solid object. As a first approximation, the constructed model describes the dynamics of the system in terms of a planar surface coating with oxygen adatoms. A simplified diagram of the adsorbent surface oxidation mechanism is presented in five stages. The reaction conditions are determined by the temperature of the crystal surface and the partial pressure of the reagent in the gas phase. The reaction is considered as a random Markov process with a discrete set of states for a stream of elementary events occurring on a fragment of an ideal square lattice of ferrous sulfide with periodic boundary conditions. For the constructed model, numerical calculations are done using a software solution and the results of computational experiments are presented. The research results analysis suggests that the presented mathematical process model of oxygen adsorption on the ferrous sulfide surface along with the software solution for simulation studies can be used to determine control parameters for various technological processes.

Qualitative Analysis of Process Hazard for Hydro-treatment of Base Oils Using Combination of HAZOP and Network Analysis

Mineral base oils are conventionally acid treated using concentrated sulphuric acid to meet various service requirements before end usage. The acid treatment is not sustainable process as it generates lots of solid waste and acid treated oils have cancer hazard. Alternative techniques are adsorption over acid treated clays and hydro-treatment using suitable catalyst. The adsorptive process is relatively better option than conventional acid treatment. However, the adsorbents require regeneration which generates lots of acidic waste water and disposal of solid adsorbents after certain adsorptive cycles and hence hydro-treatment is more sustainable than acid treatment and adsorptive process with almost zero disposal of waste. Since hydro-treatment involves handling of hydrogen at elevated temperature and pressure, safety issues associated with hydro-treatment must be duly addressed. Process Hazard Analysis (PHA) was performed for hydro-treatment of mineral base oils for continuous fixed bed reactor using combination of Hazard Operability (HAZOP) and network analysis. Simplified Process Flow Diagram (PFD) was developed and two critical nodes pre-heater (node-1) and fixed bed reactor (node-2) were selected, for which three critical process parameters namely temperature, pressure and flow were identified. The present work describes qualitative PHA using HAZOP for second node (fixed bed reactor) and two possible scenarios of thermal run away and over pressure in reactor using simplified network analysis. The network analysis helps to understand various cause and effect whereas HAZOP analysis suggests suitable preventive and mitigating action for both the scenario and continuous safer operation.