Spread Of Solutions Research Articles

Applications of Mathematics: Dispersion of soluble matter in solvent flowing through a tube under a steady pressure gradient.

This paper contains many directions such as Estuary, Solute, Concentration, and Diffusion. Including a sample tube under a steady pressure gradient, the partial differential equations, and the ordinary differential is following the solution. The result comes from the reality that a probability of a mote crossing out of the element of the cross-sectional area of the flow is independent of some position of the cross-sectional element. Thus, the solute spread over a distance proportional to t^1/2.

Modelling non-isothermal volume change and solute transport behaviours of a semi-permeable clay soil under the combined influence of mechanical loading, chemical-osmosis, and thermo-osmosis

Clays are widely used in geotechnical and geoenvironmental engineering applications and it is crucial to understand its behaviour for the dynamic field conditions. The presence of a temperature gradient across clayey soils that exhibit semi-permeable membrane (or osmotic) behaviour may promote a number of complex processes, including thermal expansion or consolidation, thermally induced osmosis, thermal diffusion, along with other flow and deformation processes. Chemical-osmosis and chemico-osmotic consolidation that are significant in isothermal conditions are also affected by temperature. Publications on chemical-osmosis, and to some extent thermo-osmosis behaviour of semi-permeable clays under coupled conditions are widely available. However, studies that include the influence of both thermo-osmosis and chemical-osmosis together are rare. In this paper, a fully coupled numerical model is presented to study the effects of both osmotic processes on thermo-hydro-mechanical-chemical behaviour of semi-permeable clays. Solute spread in a landfill clay liner is investigated under the combined influence of mechanical, thermal, and chemical loading. Model results show that the clay deformation is sensitive to thermo-osmosis; and the effects of thermo-osmotic consolidation, excess pore water dissipation, and the overall settlement increases with temperature. Variation of the source temperature from 40 °C to 80 °C yielded an increase of 11.3% of the peak soil settlement. Significant contribution of thermo-osmosis on solute transport is noticed in this study and ignoring the process substantially deviate from the realism. Up to 80% overprediction of cadmium spread is observed in the clay liner when the thermo-osmotic processes are neglected.

Difficult subarachnoid anaesthesia Prediction and Performance

Spinal anaesthesia (SA) has enjoyed a long history of success, celebrating soon its 125th anniversary. Puncturing the dura mater is considered a simple procedure, followed by a subarachnoid injection of a local anaesthetic (LA) agent into the cerebrospinal fluid (CSF). Even when the technique is performed perfectly, there is no guarantee that the block sits perfectly. Failure is not uncommon and encompasses a range from total absence of any neuraxial blockade, a partial block (insufficient height, quality or duration) or a patchy block. Table 1 lists a large number of potential causative factors that may result in a failed spinal anaesthetic, providing suggestions of solutions. Analysing each distinct phase of the procedure, i.e., spinal puncture, injection of local anaesthetic solution, spread of the local anaesthetic solution through the cerebrospinal fluid, action of the drug on subarachnoid neural tissue and patient management, are the keys to success at each stage. Mechanisms of failure of spinal anaesthesia include insufficient preparation and check of equipment and drugs, suboptimal positioning of the patient, unsuccessful puncture due to inadequate training or experience and inadequate use of needles and local anaesthetic solution.1-5 Besides operator, preparation, technique-dependent and patient-related factors (anatomical variations), there are also organisational factors (lack of block room, lack of adequate monitoring and trained personnel, insufficient time between block and onset of surgery, subsequent management following block). The use of the correct local anaesthetic (dose, volume, concentration) injected at the correct lumbar interspace is of paramount importance to produce an adequate spinal block for the right surgical intervention. Nevertheless, failures may still occur. Therefore, the anaesthetist should always have a contingency plan for a failed spinal block. Indeed, patients expect reliable surgical anaesthesia when undergoing an operation

Understanding the Microstructure Formation of Polymer Films by Spontaneous Solution Spreading Coating with a High-Throughput Engineering Platform.

An important step of the great achievement of organic solar cells in power conversion efficiency is the development of low‐band gap polymer donors, PBDB−T derivatives, which present interesting aggregation effects dominating the device performance. The aggregation of polymers can be manipulated by a series of variables from a materials design and processing conditions perspective; however, optimization of film quality is a time‐ and energy‐consuming work. Here, we introduce a robot‐based high‐throughput platform (HTP) that is offering automated film preparation and optical spectroscopy thin‐film characterization in combination with an analysis algorithm. PM6 films are prepared by the so‐called spontaneous film spreading (SFS) process, where a polymer solution is coated on a water surface. Automated acquisition of UV/Vis and photoluminescence (PL) spectra and automated extraction of morphological features is coupled to Gaussian Process Regression to exploit available experimental evidence for morphology optimization but also for hypothesis formulation and testing with respect to the underlying physical principles. The integrated spectral modeling workflow yields quantitative microstructure information by distinguishing amorphous from ordered phases and assesses the extension of amorphous versus the ordered domains. This research provides an easy to use methodology to analyze the exciton coherence length in conjugated semiconductors and will allow to optimize exciton splitting in thin film organic semiconductor layers as a function of processing.

Pruning Pareto optimal solutions for multi-objective portfolio asset management

Budget allocation problems in portfolio management are inherently multi-objective as they entail different types of assets of which performance metrics are not directly comparable. Existing asset management methods that either consolidate multiple goals to form a single objective (a priori) or populate a Pareto optimal set (a posteriori) may not be sufficient because a decision maker (DM) may not possess comprehensive knowledge of the problem domain. Moreover, current techniques often present a Pareto optimal set with too many options, making it counter-productive. In order to provide the DM with a diverse yet compact solution set, this paper proposes a three-step approach. In the first step, we employ different approximation functions to capture investment-performance relationships at the asset-type level. These simplified relationships are then used as inputs for the multi-objective optimisation model in the second step. In the final step, Pareto optimal solutions generated by a selected evolutionary algorithm are pruned by a clustering method. To measure the spread of representative solutions over the Pareto front, we present two novel indicators based on average Euclidean distance and cosine similarity between original Pareto solutions and representative solutions. Through numerical examples, we demonstrate that this approach can provide a set of representative solutions that maintain high integrity of the original Pareto front. We also put forward suggestions on choosing appropriate approximation functions, pruning methods, and indicators.

Efficient development of silk fibroin membranes on liquid surface for potential use in biomedical materials

Silk fibroin (SF) protein is versatile for the application of biomaterials due to its excellent mechanical properties, biocompatibility and biodegradability. However, the efficient way to fabricate SF membranes with special structure is still challenging. Here, we develop an efficient and simple way to create SF membranes on the liquid (i.e. subphase) surface. It is essential to prepare highly concentrated SF solution with low surface tension by dissolving the degummed SF powders in 6% (w/v) LiBr/methanol solution by one step. 95 wt% polyethylene glycol (PEG) 200 and 30 wt% (NH4)2SO4 are the subphases, on which the SF solution spreads quickly, generating nonporous and microporous SF membranes (SFM-1 and SFM-2), respectively. PEG 200 causes more ordered molecular packing (β-sheets) in SFM-1. While Fast diffusion and denaturation of SF on (NH4)2SO4 solution lead to the formation of microporous, water-unstable membrane SFM-2. Both membranes have good transparency, hydrophilicty, and mechanical properties. To fabricate antibacterial biomaterials, we design a composite membrane by SFM-1 and SFM-2 sandwiching a layer of hydroxypropyl trimethylammonium chloride chitosan (HACC) to provide antibacterial functions. The sandwich membrane has good cell viability and antibacterial properties, showing potential use for biomedical materials.

An Introduction to Patterns for the Internet of Robotic Things in the Ambient Assisted Living Scenario

The Internet of Things paradigm envisions the interoperation among objects, people, and their surrounding environment. In the last decade, the spread of IoT-based solutions has been supported in various domains and scenarios by academia, industry, and standards-setting organizations. The wide variety of applications and the need for a higher level of autonomy and interaction with the environment have recently led to the rise of the Internet of Robotic Things (IoRT), where smart objects become autonomous robotic systems. As mentioned in the recent literature, many of the proposed solutions in the IoT field have to tackle similar challenges regarding the management of resources, interoperation among objects, and interaction with users and the environment. Given that, the concept of the IoT pattern has recently been introduced. In software engineering, a pattern is defined as a general solution that can be applied to a class of common problems. It is a template suggesting a solution for the same problem occurring in different contexts. Similarly, an IoT pattern provides a guide to design an IoT solution with the difference that the software is not the only element involved. Starting from this idea, we propose the novel concept of the IoRT pattern. To the authors’ knowledge, this is the first attempt at pattern authoring in the Internet of Robotic Things context. We focus on pattern identification by abstracting examples also in the Ambient Assisted Living (AAL) scenario. A case study providing an implementation of the proposed patterns in the AAL context is also presented and discussed.

Vanadium Oxide‐Modified Triphenylamine‐Based Hole‐Transport Layer for Highly Reproducible and Efficient Inverted Perovskite Solar Cells

Inverted perovskite solar cells (PSCs) often employ triphenylamine‐based materials, such as poly(triarylamine) (PTAA), as hole‐transporting layer (HTL). However, the high hydrophobic PTAA usually induces unsatisfactory perovskite growth, resulting in inferior efficiency and reproducibility. Herein, the vanadium oxide (VOx) film is introduced to modify hydrophobic PTAA layer and establish a hydrophilic surface for high‐quality perovskite film due to the decreased surface tension with improved perovskite solution spread, nucleation, and growth. The PSCs based on PTAA/VOx HTL exhibit high power conversion efficiency up to 18.9% with a sharp increase in comparison to the 16.5% of the control device. Moreover, the reproducibility is also significantly improved, showing a much smaller standard deviation of 1.75 for 40 devices compared to the control devices of 3.64. This work demonstrates that the introduction of VOx is a promising approach in producing high‐quality perovskite films on poor‐wetting PTAA layer for high‐performance inverted PSCs.

Chitosan-Based Adhesive: Optimization of Tensile Shear Strength in Dry and Wet Conditions

Commercial adhesives present a high bond strength and water resistance, but they are considered non-healthier products. Chitosan can be considered as an interesting biosourced and biodegradable alternative, despite its low water resistance. Here, its wood bonding implementation and its tensile shear strength in dry and wet conditions were investigated depending on its structural characteristics. Firstly, the spread rate, open assembly time, drying pressure, drying temperature, and drying time have been determined for two chitosans of European pine double lap specimens. An adhesive solution spread rate of 1000 g·m−2, an open assembly time of 10 min, and a pressure temperature of 55 °C for 105 min led to a bond strength of 2.82 MPa. Secondly, a comparison between a high molecular weight/low deacetylation degree chitosan and a lower molecular weight/higher deacetylation degree chitosan was conducted. Tests were conducted with beech simple lap specimens in accordance with the implementation conditions and the conditioning treatments in wet and dry environments required for thermoplastic wood adhesive standards used in non-structural applications (EN 204 and EN 205). The results clearly revealed the dependence of adhesive properties and water resistance on the structural features of chitosans (molecular weight and deacetylation degree), explaining the heterogeneity of results published notably in this field.

Walking worker vs fixed worker assembly considering the impact of components exposure on assembly time and energy expenditure

Recently, the need for assembly systems of better following the market demand has led to the spread of alternative solutions with respect to the traditional fixed worker strategy. Walking worker systems, where operators move across the line to produce the finished product, are gaining always more interest. In this paper, a comparison between the fixed worker (FW) and the walking worker (WW) assembly strategies is provided, by taking into account their differences both in terms of performed activities during assembly and of material exposure at the assembly workstations. The evaluation is carried out through the proposal of a mathematical model, to understand the impact on assembly time and on operators’ energy expenditure. The behavior of the model is investigated both with a parametric analysis and a real case study. The results show that the FW is the best one when the system is working at its maximum throughput, while the WW strategy turns out to be preferable for the lower values of market demand, both from a time and an energy expenditure perspective.

Evolution of Smart Strategies and Machines Used for Conservative Management of Herbaceous and Horticultural Crops in the Mediterranean Basin: A Review

Preserving soil quality and increasing soil water availability is an important challenge to ensure food production for a growing global population. As demonstrated by several studies, conservative crop management, combined with soil cover and crop diversification, can significantly reduce soil and water losses. The aim of this review is to evaluate the spread of smart solutions to perform conservation agriculture (CA) well in the Mediterranean Basin, taking into account the evolution of the strategies and the machines used to perform conservative tillage systems in different contexts in the last 30 years, as well as the effects induced by their adoption on the productivity of herbaceous and horticultural crops, weed control and economic feasibility, in comparison with those obtained utilizing conventional techniques based on soil inversion.

Persistence and Spread of Solutions in a Two-Species Lotka--Volterra Competition-Diffusion Model with a Shifting Habitat

We consider a two-species Lotka--Volterra competition-diffusion model with a shifting habitat. The growth rate of each species is nondecreasing along the $x$-axis, and it changes sign and shifts ri...

Solving Multi-Objective Problems Using Bird Swarm Algorithm

This paper introduces an effective method by combining the multi-objective technique with the bird swarm algorithm (BSA) to obtain a new method called MBSA. The MBSA obtains some of the different non-dominated techniques that maintain variety amongst the optimal solutions. To verify and evaluate the effectiveness of the MBSA, collections of constrained, unconstrained, and engineering problems are measured. These problems have various Pareto front (PF) properties, including non-convex, convex, and discrete PFs. The results show that the MBSA has a good ability to obtain both a better solution spread and better convergence near the true PF. Furthermore, the quantitative and qualitative results indicate that the MBSA provides high convergence and good results in all experiments and with real-world problems against well-known algorithms in the literature.

RISe of Flight: RIS-Empowered UAV Communications for Robust and Reliable Air-to-Ground Networks

Next generation mobile networks need to expand towards uncharted territories in order to enable the digital transformation of society. In this context, aerial devices such as unmanned aerial vehicles (UAVs) are expected to address this gap in hard-to-reach locations. However, limited battery-life is an obstacle for the successful spread of such solutions. Reconfigurable intelligent surfaces (RISs) represent a promising solution addressing this challenge since on-board passive and lightweight controllable devices can efficiently reflect the signal propagation from the ground BSs towards specific target areas. In this paper, we focus on air-to-ground networks where UAVs equipped with RIS can fly over selected areas to provide connectivity. In particular, we study how to optimally compensate flight effects and propose RiFe as well as its practical implementation Fair-RiFe that automatically configure RIS parameters accounting for undesired UAV oscillations due to adverse atmospheric conditions. Our results show that both algorithms provide robustness and reliability while outperforming state-of-the-art solutions in the multiple conditions studied.

Factors and conditions for the development of the digital economy in Russia

The use of digital technologies in order to increase the efficiency of production processes, distribution and consumption of the results of economic activities, and their participation in the creation of fundamental innovative developments that allow reaching a high level of application of knowledge in the field of science and technological progress, is one of the modern economic models. The purpose of the study is to assess the factors that ensure the formation of the digital economy in Russia and develop proposals aimed at accelerating the introduction of digital technologies into the economy and social sphere. Among the factors determining the formation of the digital economy in Russia, it is necessary to highlight the following: the level of digital competency skills, the effectiveness of R&D and innovation activities, the level of development of information and communication infrastructure. As a result of the study, conclusions were drawn about the presence of the necessary prerequisites for accelerating the pace of digitalization of the Russian economy. An obstacle on this path is the lack of coordinated actions on the part of the state, business and the scientific community, the low readiness of the regulatory framework for high rates of technology development and the spread of digital solutions. In order to test the effectiveness of new developments, it seems reasonable to use digital “regulatory sandboxes”.

Localization and Spreading of Asymptotic Solutions of a Hyperbolic Equation with Variable Coefficients Describing Waves in a Channel of Variable Cross Section

Asymptotic solutions of the Cauchy problem with localized initial conditions are described for a hyperbolic equation describing waves in a channel of variable cross section. It is shown that, if the equation is reduced to a wave equation, then the solution remains localized, whereas, if the initial equation reduces to the Klein–Gordon equation, then nonlocalized corrections occur in the asymptotics.

Моделирование процессов фильтрации технологических растворов при блочном подземном выщелачивании

PAO “Priargunsky Production Mining and Chemical Association” has been working on reserves of uranium deposits of the Streltsovsky ore field for more than 50 years. During this period, most of the rich ores have been worked out by traditional mining and physical technology. The share of poor and ordinary ores remains significant, but traditional technology does not provide the necessary level of profitability. Therefore, the widespread introduction of physicochemical technology: underground block (BPV) and heap leaching (KV) can be a decisive moment in the continuation of the operation of these deposits. The applied technology of underground block leaching has one significant drawback – a low rate of uranium recovery into a productive solution, which significantly reduces the effectiveness of this technology in the development of poor uranium deposits. To increase the yield of uranium into the productive solution, it is necessary to analyze the entire preparation and leaching process and establish the main reasons for the low rates of transition of uranium to a mobile state. For this purpose, it is proposed to simulate the underground leaching process by building visual models of halos spreading of solutions along shrinked ore mining mass accumulated in an underground chamber. During the simulation, it was found that the distribution of the size classes of the broken ore pieces in the chamber can be predicted at the stage of drilling and blasting operations, and when determining the line of least resistance W and the distance between the ends of the wells, take into account the diameter of the controlled crushing zone R_p. At the same time, 3 zones of granulometric compositions are formed: a re-grinding zone, an optimum zone and a non-carbarite exit zone. The flow of solutions through these zones will differ the more significantly, the higher the height of the chamber. In a zone with larger crushing, an almost steep distribution of the solution spreading front is expected. Accordingly, the smaller the fraction, the lower the front to the horizontal is. The following functions are offered to simulate filtering processes: – it is possible to control the flow of working solutions to the fan of irrigation wells in order to achieve optimal leaching parameters, i.e. to quickly control the process; – knowledge of the law of distribution of irrigation flares makes it possible to select the optimal grid of location of single sprinklers

Online clustering reduction based on parametric and non-parametric correlation for a many-objective vehicle routing problem with demand responsive transport

In this paper, we address an online dimensionality reduction approach to deal with a many-objective formulation of a Vehicle Routing Problem with a Demand Responsive Transport (VRPDRT). The problem relates to a mode of transport similar to available carpooling services in which passengers are transported from their origin to their destination sharing the same vehicle. The goal is to reduce the operating/riding costs while meeting passenger needs and providing high-quality service. Due to the complexity and conflicting characteristics of the problem, an evolutionary approach based on a dimensionality reduction technique is applied to solve the VRPDRT in which eight different objective functions are used. The performance of the proposed approaches – OnCLτ-MOEA/D and OnCLρ-MOEA/D – are compared to an a priori cluster dimensionality reduction with Pearson’s and τ of Kendall correlation coefficients using a realistic data set containing distances and travel time for Belo Horizonte, Brazil. The online and offline versions of the algorithms are also compared with a baseline approach, a classic version of MOEA/D. Results show that the online cluster-based approach achieves a better spread of solutions, when compared to its a priori versions. Moreover, there is no difference between the results obtained from the online Cluster-based approach and the original MOEA/D. It shows that the proposed dimensionality reduction is an effective technique presenting a positive effect on the search efficiency, computational cost, and in the application of usual visualization techniques.

RETRACTED ARTICLE: The role of temperature on the global spread of COVID-19 and urgent solutions

AbstractThis study explored whether the global temperature had any role in the spread and vulnerability to COVID-19 and how that knowledge can be used to arrest the fast-spreading disease. It highlighted that for transmitting the virus, global temperature played an important role and a moderately cool environment was the most favourable state. The risk from the virus was reduced significantly for warm places and countries. Based on the temperature of March and April, various degrees of vulnerability were identified and countries were specified. The maximum reported case, as well as death, was noted when the temperature was in the range of around 275 °K (2 °C) to 290 °K (17 °C). Countries like the USA, UK, Italy and Spain belonged to this category. The vulnerability was moderate when the temperature was less than around 275 °K (2 °C), e.g. Russia, parts of Canada and a few Scandinavian countries. For temperature 300 °K (27 °C) and above, a significantly lesser degree of vulnerability was noted. Countries from South Asian Association for Regional Cooperation, South-East Asia, the African continent and Australia fell in that category. This work discussed that based on the variability of temperature, countries can switch from one vulnerability state to another. That influence of temperature on the virus and results of previous clinical trials with similar viruses provided a useful insight that regulating the level of temperature can offer remarkable results to arrest and stop the outbreak. Based on that knowledge, some urgent and simple solutions are proposed, which are practically without side effects and very cost-effective too.

An ultrasound-guided subparaneural approach to the sciatic nerve in the dog: a cadaver study

ObjectiveTo describe the gross and microscopic anatomy of the sciatic nerve paraneural sheath and to report an ultrasound (US)-guided subparaneural approach to the sciatic nerve in dogs, comparing two different volumes of injectate. Study designProspective, randomized, anatomical study. AnimalsA group of nine middle-sized adult Mongrel canine cadavers (18 limbs). MethodsThe sciatic nerves of three pelvic limbs of two canine cadavers were identified, exposed and isolated between the greater trochanter and the popliteal fossa for gross anatomical and microscopic examination. An additional three pelvic limbs were surgically dissected on the lateral surface of the limb; the sciatic nerves were isolated, and a 26 gauge over-the-needle catheter was inserted through the paraneural sheath under direct visualization. A methylene blue solution was then slowly injected into the subparaneural compartment through the catheter under US visualization using an 8–13 MHz linear-array transducer. Subsequently, 12 pelvic limbs (six cadavers) were randomly allocated to one of two groups; using US-guided percutaneous subparaneural approach, either 0.1 or 0.05 mL kg–1of a 1:1 solution of methylene blue and 0.5% bupivacaine was injected. The spread of the dye solution and the amount of nerve staining were macroscopically scored. The stained sciatic nerves with their sheaths were then harvested for microscopic examination. ResultsThe paraneural sciatic nerve sheath was easily identified distinct from the nerve trunk both macroscopically and with US visualization, and microscopically. Complete staining was achieved in five of six (83.3%) sciatic nerves in each group; no difference was found in the amount of staining between the two groups. Microscopically, no signs of sciatic nerve intraneural injection were observed. Conclusions and clinical relevanceThe US-guided subparaneural injection of 0.05 mL kg–1 of a dye injectate resulted in satisfactory nerve staining without evidence of sciatic nerve intraneural injection.