Scale Micro Research Articles

Multi-objective optimization of steam methane reformer in micro chemically recuperated gas turbine

A kinetic theory, known as the Langmuir–Hinshelwood–Hougen–Watson adsorption model, is applied to describe the steam methane reforming (SMR) in a 500 kW scale micro chemically recuperated gas turbine (CRGT) cycle. The response surface models of important performance parameters, including the methane conversion, carbon monoxide selectivity, and chemically recuperated heat as a function of the temperature, pressure, steam-to-carbon ratio, and contact time are numerically obtained based on the cases selected by the central composite design. The factors affecting the SMR performance are analyzed, and the reformer performance is optimized using both the desirability function combined with the response surface methodology and the second generation non-dominated sorting genetic algorithm. Finally, performance of the optimized reformer and electrical efficiency of the micro CRGT cycle with the reformer are evaluated. Results reveal that the efficiency of the micro CRGT is 40.70%, which is much higher than the typical high-efficiency micro gas trubine without reformer.

Predicting mechanical properties of 3D printed nanocomposites using multi-scale modeling

The main objective of this research is to predict the Young’s modulus of 3D-printed specimens made of nanocomposites. Printable nanocomposites filaments reinforced with various portions of carbon nanotubes (CNTs) are produced at the first stage. At the second stage, extruded nanocomposite filaments are fed into a 3D desktop printer and tensile specimens are printed with two different infill patterns. A multi-scale modeling is developed as a hierarchical computational procedure covering involved scales of micro, meso and macro. Treating CNT length, orientation and agglomeration as random parameters, stochastic modeling is performed. CNT length is considered at microscale, while CNT agglomeration and orientation are taken into account at the scale of meso. The infill patterns and printing parameters are captured at the uppermost scale of macro. The Young’s modulus of both nanocomposite filaments and 3D printed samples are predicted and compared with the results of experimental characterization.

Some problems of modeling the liquid cavitation degassing. I. Acoustic cavitation.

In recent decades, cavitation methods of liquid degassing have become widely used, which today have practically replaced the traditional time-consuming mechanical and chemical methods of degassing in industry. The application of cavitation methods is based on the fact that a part of the neutral gases present in the liquid is not in a dissolved state, but in a so-called "free" state in the composition of a large number of vapor-gas bubbles, the size of which is measured on the scale of micro- and nanometers. The nature of the stable, long-term existence of such micro-bubbles has not yet found a reasonable explanation and is the subject of debate among researchers. Cavitation methods of degassing, both hydrodynamic and acoustic, are aimed precisely at the rapid removal of these bubbles from the liquid together with the free gas present in them. The advantage of using acoustic cavitation methods is the ability to precisely control the frequency and intensity of ultrasound, as well as the duration of sounding. Acoustic degassing methods are based on two mechanisms: the passage of dissolved gas inside pulsating bubbles due to the effect of "directed diffusion" and the convergence and subsequent coalescence of neighboring bubbles under the influence of force Bjerknes As a result, the growing bubbles quickly float up and leave the liquid together with the free gas. In recent years, a large number of articles on the comprehensive study of acoustic degassing processes have been published. According to the authors of these publications, the mechanism of degassing at the microscopic level and all the diversity of bubble dynamics, depending on the frequency and intensity of the sound, remain unclear. This article examines the main problems of modeling acoustic degassing processes, which confirm the absence of generally accepted clear ideas about the physical nature and mechanisms of cavitation phenomena and a general approach to the analysis of the obtained results. In order to develop research in this direction, the article also presents the results of a computational experiment on the coalescence of pulsating bubbles, conducted by the authors on the basis of a model of the dynamics of a single bubble previously created by them. As a result of the theoretical study, new, previously unknown information about the force interaction of pulsating bubbles of different sizes was obtained, which can be considered as a certain contribution to the understanding of the mechanisms of acoustic degassing.

Design and Construction of a Turbine Pump as Laboratory Scale Micro Hydro Electricity Learning Media

Lack of understanding of students about renewable energy can be produced from pumps, namely electrical energy. The energy produced by this pump is beneficial for rural areas that do not have electricity. The purpose of this research is to modify the pump as a turbine for a micro-hydro power plant which can be used by students of the Mechanical Engineering Department, the University of Muhammadiyah Pontianak as learning media in the field of fluid machines and laboratory-scale energy conversion machines. The research subjects were 15 students of mechanical engineering and pumps that were converted into turbines to generate electricity. The data collected first comes from the performance test of a pump that has been converted into a pump as a turbine. Further data was obtained from students through a pretest with a conceptual type of pump used as a power plant. Then after the pretest, students were treated by using and operating a pump as a turbine as a learning media. From this media, students must also explain the concept and how the pump as a turbine can produce electrical energy in writing. The student's written results obtained were analyzed to determine the effect of the pump as turbine model on students' understanding of conceptual analysis. The result of this research is a pump that has been converted into a pump as the turbine. In addition, as a simple practical tool to test the performance of the pump as a turbine. There was an increase in students' understanding in terms of the ability to describe the concept of power generation sources from pumps and analyze the process and workings of the pump as a turbine to produce electrical energy.

Do Digital Marketing Impact Business Performance? Emerging Views from Managers and Owners of Micro, Small and Medium Scales Enterprises in Nigeria

Micro, Small and Medium Enterprises (MSMEs) are engaged in recreation and economic wellbeing of a nation. They generate diversified sources of national income, improve a country’s competitive advantage and support economic development leading to suppleness of the economies. This study examines the influence of digital marketing on MSMEs performance in Plateau State, survey research design was used, data were obtained from 130 MSMEs in Plateau State through self – administered questionnaires and the study instruments were adapted from previous studies. The study instruments were subjected to determine the validity and reliability of the research instrument and subsequently to determine the hypothesized direct relationships among the variables through multiple regression analysis method. The findings revealed that social media marketing, e – mail marketing, internet marketing, and mobile marketing, are positive related to the performance scale of micro and medium scale enterprises in plateau state, while search engine marketing has no relationship with firm performance. The implication to the study is that digital marketing has a potential as marketing strategy to influence performance of small firms, the study will be of great importance to scholars because it a new subject to explore as a marketing strategy for MSMEs in competitive environment characterized rapid change in technology

APPLICATIONS OF ROTATIONAL MANIPULATORS IN THE MANUFACTURE AND CHARACTERIZATION OF HIGHLY CURVED THIN FILMS

AbstractWhat do common devices such as smartphones, CD’s and solar panels all have in common? They are all examples of innovative technology that is still limited to flat, rigid geometries. This is primarily due to the limitations of the manufacturing processes used to create components within these devices, key among them the thin polymer films produced through spin coating.Spin coating is a technique used due to its ability to effectively create uniform films on the scale of micro or nanometres. However, it relies on a planar substrate to produce uniform layers, thus restricting the design of components manufactured using this process to simple, flat objects. As the requirement for curved device geometries expands, complex alternative fabrication methods are being implemented in industry.For spin coating to remain relevant, a viable process for controlling the fluid flow over curved surfaces must be developed. This research investigates the hypothesis that coating distributions can be controlled through optimized rotation of a curved substrate. Where a multi-axis rotational manipulator and novel characterization system have been developed to investigate the fabrication of curved devices using the improved spin coating technique.

HARNESSING PSYCHOLOGICAL CAPITAL TO AUGMENT EMPLOYEE ENGAGEMENT IN THE MICRO-FINANCE SME SECTOR

The study sought to establish the effect of psychological capital on employee engagement on small to medium scale micro finance institutions. Secondary objectives were developed using psychological capital constructs namely hope, self-efficacy and resilience. The study adopted a quantitative approach backed by positivist philosophy. A sample of 350 respondents was determined using the Yamane’s model. Stratified random sampling was adopted and data was collected using a structured questionnaire. The results of the study indicate that psychological capital has a significant effect on employee engagement. The study recommends that employee behavioral workshops, mentorship, ethical leadership and coaching programmes directed at developing psychological capital in SMEs.

Investigating long‐term creep in a composite pipe subjected to transverse loading and aqueous condition

AbstractGlass‐fiber reinforced‐polymer (GFRP) pipes are widely used in various applications under wet conditions. Despite the considerable efforts on characterizing the mechanical response of GFRP pipes from various viewpoints in dry condition, less attention has been given to the influence of moisture absorption on their performance. The main goal of this research is to investigate the influence of moisture absorption on the long‐term creep behavior of GFRP pipes experimentally and theoretically. As experimental program, a GFRP pipe is subjected to a constant compressive transverse loading while it is submerged in water. Thus, the interaction between creep and water absorption are studied up to 5000 h. A systematic modeling procedure is also developed to evaluate the long‐term wet‐creep response of the GFRP pipes. Two scales of micro and macro are linked through an explicit modeling procedure. An excellent agreement is observed between experimental observations and outputs of the developed modeling procedure.Highlights A process is developed to model long‐term creep in composites under wet condition. Long‐term creep is predicted based on short‐term creep behavior of pure resin. Long‐term creep on immersed pipe in water under the transverse loading is simulated. Updating constitutive equations, nonlinear viscoelastic behavior is estimated. The effect of moisture absorption on the long‐term creep behavior is investigated.

Microsystem Advances through Integration with Artificial Intelligence.

Microfluidics is a rapidly growing discipline that involves studying and manipulating fluids at reduced length scale and volume, typically on the scale of micro- or nanoliters. Under the reduced length scale and larger surface-to-volume ratio, advantages of low reagent consumption, faster reaction kinetics, and more compact systems are evident in microfluidics. However, miniaturization of microfluidic chips and systems introduces challenges of stricter tolerances in designing and controlling them for interdisciplinary applications. Recent advances in artificial intelligence (AI) have brought innovation to microfluidics from design, simulation, automation, and optimization to bioanalysis and data analytics. In microfluidics, the Navier-Stokes equations, which are partial differential equations describing viscous fluid motion that in complete form are known to not have a general analytical solution, can be simplified and have fair performance through numerical approximation due to low inertia and laminar flow. Approximation using neural networks trained by rules of physical knowledge introduces a new possibility to predict the physicochemical nature. The combination of microfluidics and automation can produce large amounts of data, where features and patterns that are difficult to discern by a human can be extracted by machine learning. Therefore, integration with AI introduces the potential to revolutionize the microfluidic workflow by enabling the precision control and automation of data analysis. Deployment of smart microfluidics may be tremendously beneficial in various applications in the future, including high-throughput drug discovery, rapid point-of-care-testing (POCT), and personalized medicine. In this review, we summarize key microfluidic advances integrated with AI and discuss the outlook and possibilities of combining AI and microfluidics.

Simulating the dynamics of dispersal and dispersal ability in fragmented populations with mate-finding Allee effects.

We consider the spatial propagation and genetic evolution of model populations comprising multiple subpopulations, each distinguished by its own characteristic dispersal rate. Mate finding is modeled in accord with the assumption that reproduction is based on random encounters between pairs of individuals, so that the frequency of interbreeding between two subpopulations is proportional to the product of local population densities of each. The resulting nonlinear growth term produces an Allee effect, whereby reproduction rates are lower in sparsely populated areas; the distribution of dispersal rates that evolves is then highly dependent upon the population's initial spatial distribution. In a series of numerical test cases, we consider how these dynamics affect lattice-like arrangements of population fragments, and investigate how a population's initial fragmentation determines the dispersal rates that evolve as a habitat is colonized. First, we consider a case where initial population fragments coincide with habitat islands, within which death rates differ from those that apply outside; the presence of inhospitable exterior regions exaggerates Allee effect-driven reductions in dispersal ability. We then examine how greater distances separating adjacent population fragments lead to more severe reductions in dispersal ability. For populations of a fixed initial magnitude, fragmentation into smaller, denser patches leads not only to greater losses of dispersal ability, but also helps ensure the population's long-term persistence, emphasizing the trade-offs between the benefits and risks of rapid dispersal under Allee effects. Next, simulations of well-established populations disrupted by localized depopulation events illustrate how mate-finding Allee effects and spatial heterogeneity can drive a population's dispersal ability to evolve either downward or upward depending on conditions, highlighting a qualitative distinction between population fragmentation and habitat heterogeneity. A final test case compares populations that are fragmented across multiple scales, demonstrating how differences in the relative scales of micro- and macro-level fragmentation can lead to qualitatively different evolutionary outcomes.

Three-dimensional flow simulation and cavitation erosion modeling for the assessment of incubation time and erosion rate

A compressible three-dimensional in-house flow solver is employed for the assessment of cavitation erosion. The flow solution method provides the wall load, which is coupled to a one-dimensional ductile material model and which yields the incubation time and erosion rate. Due to the assumption of a homogeneous mixture in the flow solver, details of collapsing wall adjacent single bubbles cannot be resolved, so that two different wall load models are presented. In the first method, a collapse detection algorithm based on the mass flux divergence is applied, load collectives are statistically evaluated by the multitude of detected collapses, and a spectrum of distinct loads is passed on to the material model. Since the physical simulation time is much shorter than the real exposure time, a method for the time extrapolation of the wall load to capture realistic time scales is presented. In the second method, a sub grid scale micro jet model is applied, and the wall load is approximated by mean values, so that a time extrapolation is dispensable. Both methods require calibration to e.g. experimentally measured incubation time. An application to the widely used Grenoble axisymmetric impinging jet test case reveals, that the first method fails to capture the location of maximum wear. Due to the inclusion of an erosion probability for the detection of prospectively erosive collapse events in the second method, a good match with data is obtained. Beyond a validation for a broad range of erosive flow conditions, the use of alternative material models including high cycle fatigue as important wear mechanism is planned in future studies.

Advanced polymer processing technologies for micro‐ and nanostructured surfaces: A review

AbstractFunctional surfaces with attractive properties, such as superhydrophobicity and omniphobicity often rely on the synergy between intrinsic material properties and dual scale micro‐ and nano‐hierarchical structures for achieving desired wettability. Historically, engineered liquid repellent surfaces have attracted a great deal of interest from academia and industry due to their broad application prospects. Hence, for several years, there have been significant scientific efforts by researchers exploring state of the art manufacturing technologies that are efficient and yet cost effective to produce functional liquid repellent surfaces at an industrial scale. This technical review summarizes the various advanced and state of the art polymer processing technologies employed to fabricate the micro‐ and nanostructured polymer surfaces, with a special focus given to superhydrophobic and omniphobic applications. Here, we discuss the merits and limitations of each fabrication methods available for micro‐ and nanostructuring of polymer‐based surfaces. In addition, an attempt has been made to provide insight into the relationship between geometry of micro/nanostructures (size and shape) and intrinsic wettability on liquid repellency. A special section has been devoted to feature and document all commercialization efforts, including various commercially available products that were developed in the past decade. Finally, outlook and the development trend in the polymer micro‐ and nanostructured surfaces are highlighted to lead future research.

A micro‐macromechanical approach for analyzing creep in randomly oriented short fiber composites

AbstractThe main purpose of this research is to develop a model investigating creep phenomenon in polymeric composites reinforced with randomly oriented short fibers. The creep phenomenon is first analyzed in a representative volume element of a long‐fiber composites at the scale of micro through an implicit approach. Then, creep analysis is performed at laminate level as the macro‐scale analysis. Then, creep response of a quasi‐isotropic laminate is obtained where the outputs of the micro‐scale analysis are fed as input data to the macro‐scale modeling. Laminate analogy is properly integrated with creep modeling technique to obtain the creep behavior of randomly oriented short fiber composites. The results of modeling are compared with published experimental data revealing the proper performance of the developed modeling for both short‐term and long‐term creep phenomena.

Creating a Competitive Advantage for Micro and Small Enterprises Based on Eco-Innovation as a Determinant of the Energy Efficiency of the Economy

The aim of this analysis is to identify the possibility of treating eco-innovation in micro and small enterprises as a factor influencing the energy efficiency of the economy. In order to obtain an answer to such a research question, quantitative research was carried out among Polish enterprises from the SME sector (N = 400). Accordingly, the CATI technique was applied. The selection of enterprises was random and took place in the non-returnable drawing process. The criterion for selecting the sample was the size of enterprises, but in order to ensure the possibility of drawing conclusions based on a sufficiently large research sample, its structure (300 micro and 100 small enterprises) assumed the study of small enterprises in a proportion greater than their actual share in the population of enterprises. As a result of this research, the existence of a relationship between the improvement of the company’s competitive position and its activity in the field of eco-innovation implementation was confirmed. It is shown that the behavior and attitudes of entrepreneurs largely determine the very decisions regarding the use of specific types of eco-innovation, as well as the areas in which they brought about changes influencing the improvement of the competitive position of the surveyed companies. Differences in these decisions can be observed in micro and small companies. This article justifies the notion that the impact of the scale of micro and small companies is important in shaping the energy efficiency of the economy.

PENGARUH TINGKAT PENDIDIKAN, PENGETAHUAN AKUNTANSI, UMUR USAHA DAN SKALA USAHA PELAKU USAHA MIKRO KECIL DAN MENENGAH (UMKM) TERHADAP PENGGUNAAN INFORMASI AKUNTANSI DI KECAMATAN SENAPELAN

This study aims to determine the effect of education level, accounting knowledge, business age and business scale of micro, small and medium enterprises (MSMEs) on the use of accounting information in Senapelan District. The method used in this research is simple random sampling. The type of data used is primary data. Data collection carried out in this study is the distribution of questionnaires. The sample of this study consisted of 74 businesses. Data processing was carried out using SPSS version 21 program tools. The research model used by the researcher was multiple linear regression analysis. Based on the results of the tests carried out, it was concluded that the level of education, accounting knowledge, business age and business scale had a significant effect on the use of accounting information on MSMEs in Senapelan District.

Factor Analysis of Capital, Family Support, Entrepreneur's Skill and Networking that Shapes the Success of Women Entrepreneurs in Manado City

This study was conducted to confirm the factors of capital, family support, entrepreneur’s skillsand networking as factors that shape the success of female entrepreneurs in Manado City. This study uses aquantitative research methodology with a population of female entrepreneurs in Manado City in the periodFebruary-March 2021. The sampling method used is Non-probability Sampling: Purposive Sampling,namely the selected sample has criteria that have a business that has been operating for at least 42 months,with the scale of micro, small and medium enterprises and have social media. The number of respondentsbased on filling out the questionnaire was 325. However, the data of 23 respondents was categorized asinvalid because the duration of the business was less than 3.5 years, so that only 302 respondents data whichwere declared valid were used in this study. The results of the survey as a primary source were thenprocessed using the SPSS version 25 software. The results in this study indicate that the factors of capital,family support, entrepreneur’s skills and networking are factors that shape the success of femaleentrepreneurs.

Kajian Hukum Pencemaran Lingkungan Udara Berkaitan Dengan Usaha Mikro Kecil Dan Menengah Di Kabupaten Cirebon

The existence of human life is very dependent on environmental conditions. Thus the environment has an important role in the survival of the community. However, humans need an effort as an effort to maintain life. The existence of micro, small and medium enterprises (Usaha Mikro, Kecil, dan Menengah/UMKM) is the largest part of the national economy. In Cirebon Regency itself there are still economic activities that cause air pollution. How is the implementation of the policy of the Cirebon Regional Government in an effort to overcome air pollution based on the scale of micro, small and medium enterprises based on Law Number 32 of 2009 and what is the implementation of sanctions by the Regional Government of Cirebon in overcoming air pollution. The purpose of this study is to determine the policies and implementation of sanctions carried out by the Cirebon Regency Government in overcoming air pollution. This research method is a normative juridical research, through a law approach and then described in an analytical descriptive manner. Regional Government of Cirebon carries out an environmental pollution program to tackle air pollution through two major sub-districts, namely first measuring air quality to find sources of pollution, second controlling pollution and environmental damage. The application of sanctions by the Environmental Service to perpetrators of air pollution has not yet resulted in criminal sanctions because they do not yet have an Environmental Supervisory Officer. Sanctions carried out by the Office are administrative sanctions or commonly called reprimands. Regional government of Cirebon requires business owners to have UKL-UPL permits which are used as the basis for environmental permits. The government is also obliged to protect the environment in the regional of Cirebon.

INTEREST AND DETERMINING FACTORS FOR DIGITAL PRODUCT ADOPTION: A CASE OF TAPE MAKERS IN MALANG, INDONESIA

Marketing using digital products is one way to do marketing through social media that uses the internet. The purpose of this study was to determine the interest of tape makers in the use of digital products and the factors that influence them. The sampling method used the survey method and obtained 45 respondents of tape makers on the scale of Micro, Small and Medium Enterprises (MSMEs) in Banjarsari Village, Ngajum District, Malang Regency. The descriptive analysis method is used to analyze the interest of tape makers in the use of digital products. While Partial Least Square (PLS) analysis is used to analyze the factors that influence the interest of tape makers in digital products. The results showed that tape makers have an interest in digital products in marketing tape. However, tape makers are not interested in applying or using digital information products in marketing tape. This is due to several factors that influence significantly, including advances in information technology, the ability of tape makers, environment, competition, and capital.

Estimating the burst pressure of a filament wound composite pressure vessel using two-scale and multi-scale analyses

The influence of inescapable imperfections associated with fiber arrangement in the filament winding process on the burst pressure of a composite vessel is analyzed. Firstly, the influence of fiber packing, fiber spacing and fiber contiguity is analyzed through a two-scale analysis. Mechanical properties of the layers are estimated considering aforementioned parameters at the scale of micro and the burst pressure is estimated at the scale of macro. As the second approach, fiber-bundle crossovers and undulation arisen from filament winding process are also considered at the scale of meso. Thus, a multi-scale modeling is performed capturing micro, meso and macro scales.

Solids lateral mixing and compartmentalization in dynamically structured gas–solid fluidized beds

An adequate use of gas pulsation can create an ordered, dynamically structured bubble flow in a bed of Geldart B particles. A structured bed is more homogeneous, responds to external control and is scalable. While earlier studies have focused on describing the self-organization of the gas bubbles, the solid mixing and gas–solid contact patterns have remained unclear. In this work, the solids circulation and mixing behavior in structured and unstructured beds at various pulsation frequencies are compared with a traditional fluidized bed operation. The degree of lateral mixing is hereby quantified through an effective lateral dispersion coefficient extracted from CFD-DEM (discrete element modelling) simulations in a thin fluidized bed system. Mixing shows major quantitative and qualitative differences amongst the investigated cases. The coordinated motion of the gas bubbles wraps the solid flow into a series of compartments with minimal interaction, whereby effective lateral dispersion coefficients are an order of magnitude lower than in an unstructured operation. More importantly, unlike a traditional bed, dispersion in a structured bed is driven by advection and is no longer a diffusive process. Compartmentalization decouples the time scales of micro- and macromixing. Every pulse, the compartments rearrange dynamically, causing a level of local axial mixing that is scale-independent. While further work is necessary to fully understand the compartmentalization at a larger scale, the circulation described here indicates that a dynamically structured bed can provide a tight control of mixing at low gas velocities and a narrower distribution of stresses in the solid phase compared to traditional devices.