Present Problems Research Articles

Trend Analysis as a Methodological Reference for Startup Strategy in the New Normal

The objective of this work is to analyze the current competitive context of technology-based companies called Startup based on a documentary review in order to propose strategies that allow their relative and absolute growth, taking as a reference the change in lifestyles and restrictions that citizenship derived from the Covid 19 pandemic has faced. The approach is qualitative based on realistic theories; Data was collected fromupdated books on the subject, articles and scientific journals, to analyze the effectiveness of previous research applicable to the present research problem. Results. Startups can enhance their services through continuous innovation, individually or in association with others. It is concluded that, given the new opportunities derived from the changes in consumer habits, they will be able to consolidate themselves by including in their strategy adapting to trends, developing agile capacities for fluid timesand practicing corporate activism.

DarwinGSE: Towards better image retrieval systems for intellectual property datasets.

A trademark's image is usually the first type of indirect contact between a consumer and a product or a service. Companies rely on graphical trademarks as a symbol of quality and instant recognition, seeking to protect them from copyright infringements. A popular defense mechanism is graphical searching, where an image is compared to a large database to find potential conflicts with similar trademarks. Despite not being a new subject, image retrieval state-of-the-art lacks reliable solutions in the Industrial Property (IP) sector, where datasets are practically unrestricted in content, with abstract images for which modeling human perception is a challenging task. Existing Content-based Image Retrieval (CBIR) systems still present several problems, particularly in terms of efficiency and reliability. In this paper, we propose a new CBIR system that overcomes these major limitations. It follows a modular methodology, composed of a set of individual components tasked with the retrieval, maintenance and gradual optimization of trademark image searching, working on large-scale, unlabeled datasets. Its generalization capacity is achieved using multiple feature descriptions, weighted separately, and combined to represent a single similarity score. Images are evaluated for general features, edge maps, and regions of interest, using a method based on Watershedding K-Means segments. We propose an image recovery process that relies on a new similarity measure between all feature descriptions. New trademark images are added every day to ensure up-to-date results. The proposed system showcases a timely retrieval speed, with 95% of searches having a 10 second presentation speed and a mean average precision of 93.7%, supporting its applicability to real-word IP protection scenarios.

Empirical analysis of dust and noise pollutants produced in the wood-CNC machining process.

In the manufacturing processes, consideration of sustainability is of particular importance. The current study is concerned with the influences of changing the process variables on the reduction of pollutions in the wood-CNC machining operation. Noise and dust are the studied pollutants in the present research work. Process variables include feed rate, spindle speed, step-over, and depth of cut, and the aim is to predict the behavior of aforementioned pollutants variations in the current process. The amounts of these harmful factors are measured based on existing standards. In order to analyze the findings, adaptive neuro-fuzzy inference system (ANFIS) and regression analysis methods have been employed, separately. The effects of process parameters on response variables have been comprehensively studied. The research findings demonstrated that for the present problem, ANFIS outcomes are more accurate. According to the mean absolute error (MAE) criterion, the prediction errors of ANFIS for noise and dust factors were computed to, in turn, 0.50 and 14.89. Meanwhile, the error values for prediction of noise and dust responses using regression analysis were calculated as 1.54 and 34.62, respectively.

The Use of Nano-based Drug Delivery Systems for Neurodegenerative Disorders

ABSTRACT Blood–brain interfaces surrounding the central nervous system (CNS) present problems for targeted drug delivery, which limits the bioavailability of therapies for the diagnosis and treatment of neurological illnesses such as Alzheimer’s diseases and Parkinson’s diseases (AD/PD). Over the past 10 years, research has concentrated on creating novel approaches to get around these restrictions and effectively transport medications to the CNS. The protective barriers surrounding the CNS can be penetrated by nanoparticles (NPs), which have the ability to encapsulate medicines with prolonged drug release patterns and customizable physiochemical properties. To find out more about drug delivery systems, blood–brain barrier, NPs, neurodegenerative illnesses, AD and PD, and their treatment applications, a ScienceDirect, PubMed, and Google Scholar search was done. After analysis using the keywords/phrases, relevant articles were determined to be completed. Because nanotechnology is a potent substitute for traditional drug delivery systems, it thus offers new hope for the treatment of AD and PD for example. The possible use of techniques based on NPs in neurodegenerative disorders and their therapeutic implications are covered briefly in this work.

MHD nonlinear thermally radiative Ag − TiO 2/H 2 O hybrid nanofluid flow over a stretching cylinder with Newtonian heating and activation energy

Hybrid nanofluids are significant in biomedical, industrial, transportation, as well as several engineering applications due to their high thermal conductivity and mass transfer enhancement nature in contrast to regular fluids and nanofluids. Taking this into consideration, the present problem explores the flow of hybrid nanofluid (Ag − TiO 2/H 2 O) over a stretching cylinder subject to Newtonian heat and mass conditions. The novel aspect of the current work is to analyze the heat and mass transfer characteristics of MHD hybrid nanofluid flow on Darcy-Forchheimer porous medium in addition to activation energy, nonlinear thermal radiation, heat generation/absorption, viscous and Joulian dissipation. Further, Silver (Ag) and Titanium oxide (TiO 2) are the constituent nanoparticles of the water-based hybrid nanofluid owing to their stable chemical features and extensive industrial manufacturing. By introducing suitable similarity transformations, the governing partial differential equations (PDEs) of the developed model are reduced to ordinary differential equations (ODEs), and then the numerical solution is procured with shooting technique by using MATLAB solver bvp4c. The influence of the pertinent parameters is depicted graphically and described elaborately. The analysis indicates that velocity exhibits a declining trend against the permeability and Forchheimer parameters, while the temperature profiles show opposite behavior. The radiation and conjugate heat parameters (R, γ 1) upgrade the heat transfer rate, while the curvature and conjugate mass parameters (α c , γ 2) amplify the mass transfer rate. The maximum heat transfer rate of Ag − TiO 2/H 2 O hybrid nanofluid is 2.3344 attained for γ 1 = 0.6. The investigation demonstrates larger heat and mass transfer rates for Ag − TiO 2/H 2 O hybrid nanofluid than Ag − H 2 O nanofluid. The outcomes of the present investigation have practical applications in conjugate heat transfer over fins, development of vaccines, effluent treatment plants, solar cells, heat exchangers, and many more. An excellent agreement is achieved on comparing our numerical results with the published results in the literature.

Numerical heat transfer analysis of bio convective flow of non-Newtonian nanofluid with Darcy-Forchheimer effect over a curved stretching surface

The main aim of this study is to investigate the behavior of bio-convective flow of 2nd grade micropolar nanofluid with Darcy-Forchheimer law over a curved porous stretching surface. The fluid flow analysis includes novel aspects such as the nonuniform heat source/sink, Joule heating, magnetic field, chemical reaction, and thermal radiation. Furthermore, the boundary of the stretching surface is acquired the stratification conditions. A suitable conversion method is employed to transform the flow model into a collection of ordinary differential equations, characterized by their nonlinearity. The bvp4c technique on the MATLAB is utilized to acquire numerical solutions for this set of nonlinear equations. The characteristics of various influential parameters on the velocity, temperature, concentration, and microorganism density profiles are observed and discussed. In the present problem, it is observed that by the growth of micropolar parameter enhances the angular fluid velocity. Moreover, larger values of the magnetic parameter, Darcy number, and porosity parameter result in a decrease in the fluid’s linear velocity. The temperature profile exhibits a decreasing pattern with the elevation thermal stratification parameter, while the opposite trend shows by the increment of the radiation parameter and Eckert number. Additionally, the concentration of nanoparticles decreases as the Schmidt number and Brownian motion parameter increases.

The present situation, problems and countermeasures of small-scale Rural School Teachers in western China

The present situation, problems and countermeasures of small-scale Rural School Teachers in western China

Characterisation of the internal friction angle of waste rock material from large triaxial tests using the contact dynamics method

ABSTRACT The Chilean copper mining industry generates large amounts of waste rock materials. These structures must be designed, operated, and closed considering their physical stability. Although these structures generally do not present physical stability problems, superficial failures may occur, where waste rock material is subjected to low confining pressures. The identification of the internal friction angle, necessary for stability calculations, is based on the characterisation of these materials under high confining pressures. This assumption is not representative of the loading conditions in the superficial layers. To address this issue, numerical large-scale triaxial tests, using the contact dynamics method, are performed to identify the internal friction angle of these materials under low confining pressures. To model these material, irregular polyhedrons were generated using statistical data of crushed aggregates, considering the morphology and the particle size distribution from experimental waste rock materials. The proposed numerical approach was validated by comparing it to literature data for confining pressures over 0.5 MPa. Our results indicate that the internal friction angle stabilises at 39° for confining pressures below 0.1 MPa. This study provides important insights into the physical stability of waste rock dumps and contributes to the development of more accurate stability calculations for these structures.

Radiative squeezed flow of magnetized Prandtl-Eyring fluid over a sensor surface under Soret effect

The central aim of this numerical analysis is to describe the effects of magnetic body force and thermal radiation on the boundary layer flow of Prandtl-Eyring fluid over a sensor surface suspended between two parallel plates. The considered fluid flow is two-dimensional unsteady electrically conducting and viscous incompressible in nature. A novel Soret effect is included in the concentration equation to reveal the significant features of mass diffusion mechanism under the influence of external squeezing mechanism. Surface permeable velocity concept is also included in the boundary conditions to describe the suction/injection process. However, squeezing flows find their abundant applications in bio-medicine, medical and bio-technology areas. Particularly, the micro-cantilevers with physical or chemical sensor surfaces are effectively used in the bio-medical applications for the finding of various hazardous or bio-warfare agents’, infections, hazardous virus, nuclear reactor cooling, polymer processing, pharmaceutical, blood flow, injection molding and many more. Thus, inspired by these practical applications of squeezing flows, the present problem is modeled based on the investigated geometry. The present physical problem gives the highly nonlinear coupled unsteady two-dimensional partial differential equations and which are not amenable to any of the direct methods. Owing to this reason, the appropriate similarity transformations are used to diminish the dimensional complexity of the emerged partial differential equations (PDEs). Thus, a robust Runge-Kutta -4th order scheme (RK-4) is used as a basic tool to obtain the similar solutions of the governing equations. The graphical visualization is used to analyze the computer generated numerical data in the boundary layer regime for the different set of physical parameters. It is observed that, the enhancing magnetic number ( 0.1 ≤ M ≤ 2.7 ) in the flow region 0 ≤ η ≤ 3 increases the velocity field and decreases the temperature and concentration fields. Increasing squeezed flow index ( 0.1 ≤ b ≤ 2.5 ) in the flow domain 0 ≤ η ≤ 3 decreased the fluid velocity, temperature and concentration fields. This result may be useful in sensor surface cooling process. Rising Prandtl-Eyring fluid parameters in the range 0 ≤ η ≤ 3 decreased the velocity field and enhanced the temperature and concentration profiles. Increasing Soret number ( 0.1 ≤ Sr ≤ 0.9 ) in the flow domain 0 ≤ η ≤ 3 enhances the concentration field. Enhancing magnetic and squeezed flow numbers amplifies the skin-friction coefficient on the sensor surface. Enhancing radiation parameter increases the heat transport rate. Increasing Soret number magnifies the concentration transport rate. Finally, it is explored that, the current similar results displaying good agreement with the formerly published results in the literature and this fact confirms the accuracy and guarantee of the RK-4 method and present similar results.

Stratified numerical heat and mass transport mechanism in MHD Maxwell fluid flow with nonuniform heat source/sink

The present boundary layer flow of Maxwell fluid over a stretching sheet has good number of practical applications in metallurgy, drawing of plastics, polymer sheet extrusion including hot rolling extrusion, glass blowing, spinning of fibers, rubber and plastic sheets, crystal growing and many more. Due to these extensive applications of Maxwell fluid in engineering, medicine and manufacturing industries including the above-mentioned applications, authors have motived, inspired and investigated the present problem. However, in this research paper, the influences of Soret and Dufour effects on the steady-state Maxwell fluid flow past a stretching sheet with nonuniform heat source/sink are considered numerically. The thermal and concentration stratifications impacts are also incorporated. The viscous dissipation and magnetic field effects are also included in the respective governing equations. The main novelty and uniqueness of this numerical research is to generalize the earlier studies and describe the salient features of magneto-thermo visco-elastic dissipative Maxwell fluid motion about a stretching sheet with cross-diffusion effects under the influence of double stratification phenomena. To differentiate the non-Newtonian fluids from those of Newtonian fluids, a well-known Maxwell fluid flow model is used in the present study. The investigated physical problem results the highly nonlinear coupled partial differential equations (PDEs) and which are not amenable to any of the direct methods. Suitable similarity transformations are deployed to reduce the highly complex PDEs into the system of ordinary differential equations (ODEs). A robust BVP4C Matlab function is employed to solve the rendered dimensionless system of ODEs. The numerically generated computed data is plotted in terms of velocity, temperature and concentration profiles including engineering quantities of interest such as skin-friction, Nusselt and Sherwood numbers in the flow region. It is evident from the current analysis that, the amplified magnetic field decreases the velocity field and increases the thermal and concentration distribution fields. Accelerating Maxwell’s number diminished the flow velocity and increased the temperature field. Increasing Soret and Dufour numbers enhances the concentration and temperature fields, respectively. Amplifying Maxwell’s number raises the skin-friction coefficient and enlarging the thermal stratification parameter magnifies the thermal transport rate. The mass transport rate amplified with a raise in concentration stratification number in the flow region. Finally, it is provided that, the current results are excellently matching with earlier published results in the literature and it confirms the accuracy of the used numerical method and the produced similarity solutions.

Investigation of the wave solutions of two space–time fractional equations in physics

In this study, two fractional differential equations describing the characteristics of three-dimensional nonlinear ion-acoustic waves (IAWs) in plasmas are considered with the conformable fractional derivative (CFD). 3+1-dimensional space–time fractional Jimbo–Miwa (JM) equation and 3+1-dimensional space–time fractional modified KdV–Zakharov–Kuznetsov (mKdV-ZK) equation are reduced into ordinary differential equations and an investigation into the exact solutions is carried out through the modified exponential function method (MEFM). These exact wave solutions are beneficial in interpreting the interior structure and characteristics of physical phenomena modeled by the aforementioned nonlinear evolution equations (NLEEs) arising in magnetized plasma. Various analytical methods were applied to such equations. Therefore, it is vital to determine the proper technique for the present problem. The proposed scheme has demonstrated a different spectrum of wave structures. The portrait of the exact solutions permits the exploration of plasmas, plasma models, and optics. The software system Mathematica is employed and the rational, exponential, trigonometric, and hyperbolic function solutions are acquired. The graphical results are presented for the physical nature of the solutions. The results are compared with the integer-order models.

Calcinosis Prevalence in Autoimmune Connective Tissue Diseases-A Retrospective Study.

Background/Objectives: Calcinosis cutis is the deposition of insoluble calcium salts, which may cause inflammation, ulceration, pain, and restricted joint mobility. It rarely develops in damaged tissues (dystrophic subtype), most frequently in autoimmune connective tissue diseases (CTDs), but there is very limited data on the prevalence. Also, therapy remains an unsolved issue. In this study, we aimed to collect data on the prevalence of calcinosis in CTD patients to highlight that it is a considerable problem. Methods: A retrospective study was conducted in our department to assess the epidemiology of dystrophic calcinosis in CTDs between January 2003 and January 2024. Results: A total of 839 CTD patients were identified, of whom 56 had calcinosis (6.67%). The mean age of the calcinosis patients at diagnosis of underlying CTD was 41.16 ± 19.47 years. The mean time interval from the onset of calcinosis was 5.96 ± 8.62 years. Systemic sclerosis was the most common CTD complicated by calcinosis (n = 22). Conclusions: Our results are comparable to those reported previously in the literature. Although calcinosis is rare in the overall population, it is a present and unsolved problem in CTD patients. Therefore, further studies are needed on the factors involved in the development and progression of calcinosis as well as its treatment.

Numerical performance of Hall current and Darcy-forchheimer influences on dissipative Newtonian fluid flow over a thinner surface

Present problem concerns may be found in a wide variety of various industries and can takes a shape of round toroid's, cones, cylinders, domes (Axisymmetric shape), and other shapes as well. When it comes to actual applications, they are represented by aerosol cans, submarine pressure hulls, cooling towers, offshore drilling rigs, radomes, nuclear reactors, and other similar objects. The aim of this research is to improve the performance of MHD flow using Darcy-Forchheimer, viscous dissipation, porous and a heat source. The viscous convective permeable flow flowing over a bullet-shaped item is examined. Using similarity transforms, the structure of nonlinear differential equations are converted into dimensionless ODEs. Employing bvp4c shooting technique to decrypt the findings. Influences of physical entities on velocity and temperature were sketched and briefly described. Physical behaviors of skin friction and heat transfer rates are explored. The fluid velocity drops for Eckert number Ec as ε < 1.0, and rises as ε > 1.0, The fluid velocity improves with Darcy-Forchhemier parameter Fr when stretching ratio ε < 1.0 or = 1 or >1.0. The enhancement of fluid temperature is observed with enhanced Ec. A enhance in the Darcy-Forchhemier parameter Fr associated with improvement in skin-friction. In the absence of viscous dissipation, hall current, porous and Dacy-Forchhemier influences, the outcomes are in splendid covenant with those of previous studies.

Recent Progresses in Quantum‐Dot‐Sensitized Solar Cells: The Role of Counter Electrodes

Energy demand, global warming, environmental impacts, sustainability, and energy sources are some of the concerns faced by humanity. Quantum‐dot‐sensitized solar cells (QDSSC) are an alternative solution to addressing some of these issues, in addition to reducing the costs of producing electrical energy. However, QDSSCs present stability problems and low efficiency, less than 16%. In light of this challenge, this review aims to present the main strategies adopted to reduce energy losses that occur in each component of the solar cell, with a focus on one key component: the counter electrode (CE). The CE plays a crucial role in collecting electrons and regenerating the electrolyte, thus impacting the lifespan and efficiency of QDSSCs. As such, this review discusses the main advancements in CEs based on key materials such as metal sulfides, carbonaceous materials, and composites. The efforts related to the synthesis and application of different counter electrodes for QDSSCs are explored.

Analytical solutions in the modeling of the endovenous laser ablation

We modeled the operative treatment of incompetent truncal veins using endovenous laser ablation (EVLA). The main concern regarding the thermoablative technique is tissue damage, which is correlated with (1) the energy provided by the laser power and (2) temperature distribution. Our objective was to accurate the two functions, namely the fluence rate and the temperature, depending on the thermoablative technique and the endovenous laser treatment (ELT). First, we considered three differential equations: diffusion, heat, and bioheat equations in the endovenous-perivenous multidomain to describe the lumen, the vein wall, the tissue pad, and the skin. Second, we examined the power source according to the Beer-Lambert law in the incident beam irradiance and the heat source as the so-called absorbed optical power density. Third, we checked out the heat transfer at the skin boundary according to Newton’s law of cooling, which stands for a Robin boundary condition. For this new model, we proposed exact solutions: applying differential equations techniques, we solved (1) a diffusion approximation of the radiative transfer equation under the considered power source, and (2) the coupled heat and bioheat equations under the considered heat source accomplished with the Robin boundary condition. Then, we graphically illustrated the fluence rate profile and discussed its time dependence and steady state. Besides, we discuss thermal damage to the vein-tissue system and present open problems.

Numerical assessment of viscoelastic tetra hybrid nanofluid flow across a stretchable rotatory disk under the Soret and Dufour aspects

PurposeFluid flows through rotatory disks are encountered in industrial and practical engineering processes, such as computer storage devices, gas turbine rotators, rotating machinery, air cleaning machines, etc. The primary purpose of this research is to examine the combined aspects of variable electrical conductivity, thermal radiation, Soret and Dufour effects on a magnetohydrodynamic Maxwell single-walled carbon nanotubes–graphene oxide–multi-walled carbon nanotubes–copper (SWCNT–GO–MWCNT–Cu)/sodium alginate tetra-hybrid nanofluid flow through a stretchable rotatory disk.Design/methodology/approachThe modeled administrative equations of the present flow problem are converted to a non-dimensional system of ordinary differential equations by applying suitable similarity conversion and then solved numerically by implementing the bvp4c method. The impressions of noteworthy dimensionless parameters on velocity, temperature, concentration distributions, Nusselt number, skin friction and Sherwood number are reported via graphs and tables.FindingsThe authors figured out that the developed values of the rotation parameter diminish the temperature but enhance both the radial and angular velocities. Further, the mass and heat transmission rates are better for tetra-hybrid nanofluids than for ternary and hybrid nanofluids.Originality/valueThe present study emphasizes a special type of fluid called the tetra-hybrid nanofluid. The existing literature has not discussed the Maxwell tetra hybrid nanofluid flow through a stretchable rotatory disk with variable electrical conductivity. Besides, the novel aspects of magnetohydrodynamics, thermal radiation, Soret and Dufour effects are also incorporated into the present flow problem.

Research on the Present Situation, Problems and Countermeasures of Digital Transformation of Small and Medium-sized Private Enterprises

Research on the Present Situation, Problems and Countermeasures of Digital Transformation of Small and Medium-sized Private Enterprises

Innovative Approach to Promoting Walkability in Lisbon

The increases in both the elderly population and urbanization present new problems for planning new cities and managing old cities. To solve this challenge, innovative ideas/proposals that encourage walkability and reduce fossil energy motor transport are needed, in line with the actions advocated by Sustainable Development Goal #11 (SDG11), Sustainable Cities and Communities. Opening passages that cross blocks, creating connections between the streets, is the proposal discussed in this paper, as seen in cities like Paris, Prague, Milan, and Juíz de Fora, which have passages in their urban fabric. These can be implemented in a building’s rehabilitation or when a new building replaces it. New architectural project designs should have several characteristics that promote walkability in the city, including passages and galleries. Although previous research has obtained promising results, extending the research to different urban fabrics and block sizes is needed. Using space syntax and data analysis, we simulated and quantitatively assessed the walkability of three neighborhoods in Lisbon, Portugal. The comparison of all simulations and the discussion of the results show that the passages improve walkability. It is also noticeable that there is higher walkability in orthogonal urban fabrics than in non-orthogonal fabrics. The results for block size are inconclusive.

Numerical Study of Natural Convective Flow of a Nanofluid Over Rotating Truncated Cone with Convective Heating

In this paper, we consider the natural convection flow of a nanofluid simultaneously heat and mass transfer over a truncated rotating porous cone with convective boundary condition. Buongiorno’s model is used to describe the present nanofluid flow problem which is represented by Brownian motion and thermophoresis effects. Governing set of nonlinear boundary layer equations for the nanofluid over a rotating truncated cone is converted into a set of non-similar forms through non-similarity transformations. The obtained reduced nonlinear PDE system is linearized locally and solved via an accurate Chebyshev Spectral Collocation Method. The accuracy of the obtained numerical solutions is tested against existing results in the literature for specific cases and demonstrates good agreement. In addition, the impacts of active parameters such as the rotational parameter (0 ≤ χ ≤ 3), Biot number (0.1 ≤ Bi ≤ 1), and suction/injection parameter (−0.5 ≤ fw ≤ 0.5) on velocities, temperature, and nanoparticle volume fraction profiles along with heat and mass transfer rates are examined. It is found that the local surface drag and heat transfer rate increase, and the nanoparticle mass transfer rate decreases, with the increase in both the spinning parameter and Biot number.

Numerical study of flow past two square cylinders with horizontal detached control rod through passive control method

A two dimensional (2-D) numerical study is conducted through the lattice Boltzmann method for flow past two square cylinders with a detached control rod placed in the horizontal position of the channel. The range of Reynolds number (Re) is fixed at Re = 150, with the length (l) of the control rod varying from l = 0.1d–21d. First, we check the accuracy of grid points and the validity of the code for present problems by comparing the results with already available data in the literature. After that, we discussed the obtained results in terms of vorticity contour, drag and lift coefficients, and force statistics. In our study of flow structure mechanisms, we examined four types of flow regimes: a small length control rod, a small and moderate length control rod, a moderate length control rod, and a larger length control rod according to flow behavior. In force statistics, we calculated the values of CDmean, CDrms, CLrms, CDamp, CLamp, and St, respectively. The mean drag coefficient contains the smallest values at the largest length, i.e., l = 19 and 21d. The maximum value of CDmean is examined at the first cylinder (C1) as compared to the second cylinder (C2) at l = 2.25d, and it is 1.2789. The values of CDmean for C2 at the length of the control rod, l = 0.1d–1.25d, and at l = 21d are negative due to the effect of thrust. The value of the Strouhal number is the same for both cylinders C1 and C2, and its highest value is 0.1036. The pressure amplitude of the drag coefficient is maximum for C1, while the pressure amplitude of the lift coefficient is maximum for C2, and its value is 2.1569.