Engineering Work Research Articles

Numerical and experimental investigations of flow separation control through a linear compressor cascade

Modern large-scale gas turbines are equipped with high-pressure ratio compressors to increase engine work and its overall efficiency. Flow separation and energy losses are also two interrelated phenomenon associated with changes in compressor loading level and performance. This paper examines therefore the control of flow separation using a passive-control technique. An arced divergent-convergent slot grooved from the blade pressure side to its suction side was adopted to control flow separation, reducing the losses through a linear compressor cascade. The spanwise location of the slot was selected based on CFD simulations where the corner separation was predicted. The slot height in the spanwise direction was selected to be 8% of the blade height at the end-wall side. The present work was performed experimentally and numerically at an inlet Reynolds number,Rec=ρV∞C/μ=2.98×105\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${R}_{ec}=\\rho {V}_{\\infty }C/\\mu =2.98\ imes {10}^{5}$$\\end{document}, covering a wide range of incidence angles from +6∘to-6∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$+ 6^{ \\circ } {\ ext{ to}} - 6^{ \\circ }$$\\end{document}. The experimental work was carried out using a linear cascade test section consisting of six NACA 65-009 blade profiles integrated into a low-speed wind tunnel. A five-hole pressure probe system was used to obtain main flow parameters. Numerically, four turbulence models, including Spalart–Allmaras (S–A) model, Realizable (R k-ε) model, Shear-Stress Transport (SST k-ω) model, and Reynolds Stress model (RSM) were tested to predict the velocity and pressure fields. Good agreement between the experimental measurements and the numerical results, which were obtained using the RSM turbulence model in terms of velocity profiles and total pressure downstream of blades. It was observed also that the use of the arced-slotted blades for positive incident angles was more effective in reducing the separation than the negative and zero incident angles, approaching a maximum value of 33% for 6° with enhanced blade loading reaching 17.6%. It is to be concluded that, the use of arced slotted blade improves the compressor performance specially for positive incident angles.

QACDes: QoS-aware context-sensitive design of cyber-physical systems

There is a lot of confusion and ambiguity regarding the quantification of the Quality of Service (QoS) of a system, especially for cyber-physical systems (CPS) involved in automating or controlling the operations in built environments and critical urban infrastructures, such as office buildings, factories, transportation systems, smart cities, etc. In these cases, the QoS, as experienced by human users, depends on the context in which they (i.e., humans) interact with these systems. Traditionally, the QoS of a CPS has been defined in terms of absolute metrics. Such measures are unable to take into account the variations in performance due to contextual factors arising out of different kinds of human interactions. Further, the QoS of a CPS has typically been evaluated by comparing the performance of the actual, fully realized system with the given QoS constraints only after the actual system has been completely developed. In the case of faults in the design exposed by observed deviations from the QoS constraints due to unpredicted variations in the contextual factors, the system needs to be re-designed and re-developed from scratch. Due to the above-mentioned reason, the validation approach associated with the traditional QoS makes the design of CPS systems prohibitively expensive, impractical, as well as infeasible in numerous application areas, such as civil and engineering works, since it may not be possible to modify the system once developed beyond a certain extent. To that end, we propose a context-aware definition of QoS of a CPS which facilitates the design of robust systems as elaborated below. In this paper, we define QoS as a function of contextual factors. A CPS designed according to our QoS specifications would always satisfy the QoS irrespective of any possible changes in contextual factors resulting from many different human interactions that may occur during operation of the system. We also present QACDes - a novel framework that provides a formal mechanism for validating the design of a CPS with respect to the specified QoS constraints at the design phase as well as after the realization of the actual system. QACDes can validate any given CPS, irrespective of its application domain, against a QoS guarantee: (A) as early as even before the design phase by comparing the proposed model with a baseline model, or (B) after the realization of the actual system based on logs collected from running the actual system. We consider a lighting control system that manages the light switches - switching it on/off depending on contextual factors, such as the presence of occupants and time of the day. Using the lighting control system in a building as a use case, we analyze and demonstrate the effectiveness of our QoS definition as well as the QACDes framework against the performance metric measured in an actual fully-realized CPS.

On the importance of CI/CD practices for database applications

SummaryContinuous integration and continuous delivery (CI/CD) automate software integration and reduce repetitive engineering work. While the use of CI/CD presents efficiency gains, in database application development, this potential has not been fully exploited. We explore the state of the art in this area, with a focus on current practices, common software tools, challenges, and preconditions that apply to database applications. The work is grounded in a synoptic literature review and contributes a novel generic CI/CD pipeline for database system application development. Our generic pipeline was tailored to three industrial development use cases in which we measured the benefits of integration and deployment automation. The measurements demonstrate clearly that introducing CI/CD had significant benefits. It reduced the number of failed deployments, improved their stability, and increased the number of deployments. Interviews with the developers before and after the implementation of the CI/CD show that the pipeline brings clear benefits to the development team (i.e., a reduced cognitive load). These findings put current database release practices driven by business expectations, such as fixed release windows, in question.

Research on Automated Modeling Technology of Sluice Gate Project Based on BIM Technology.

In order to improve the efficiency and accuracy of the modeling and design work of the sluice gate project, this paper proposes an automatic generation template of the sluice gate project with customized semantics and project layout scheme, aiming at realizing the rapid assembling of all kinds of components of the sluice gate project. In the construction process, this paper first starts from basic parametric modeling and proposes constraints as the basis of modeling. Subsequently, a template library framework is developed based on the constraints to ensure that the generated templates have a high degree of standardization and consistency. Finally, an efficient and flexible template library is successfully constructed by using the customized classes and functions of Revit API, which provides powerful technical support for the modeling and design work of sluice gate engineering. This achievement helps to promote the informationization and intelligent development of the water conservancy engineering industry, and its versatility and scalability also make it have a wide range of application prospects in other water conservancy engineering fields.

Perfusionist education in Japan: A survey of challenges and current status.

This study aimed to examine the educational challenges faced by perfusionists in Japan. Although Japan has over 400 cardiovascular surgery centers, it performs fewer surgeries than by countries such as Germany and the United States. We focused on challenges related to varying caseloads and working conditions. We conducted an online survey containing 24 questions using Google Forms from January to June 2022, targeting perfusionists in Japan. The 24-question survey spanned various educational topics and was approved by the Morinomiya University of Medical Sciences Ethics Committee. Responses were received from 129 perfusionists across 77 institutions. Approximately 70% of these centers managed less than 200 cardiopulmonary bypass (CPB) cases per year, with a similar proportion of perfusionists handling under 50 CPB cases annually. Challenges in Japanese perfusionist education include enhancing communication and troubleshooting skills and the need for instructors with a broad teaching experience. This study emphasizes the significant differences in caseload and work environments for perfusionists among Japanese institutions. Perfusionists, who often work in clinical engineering, have various responsibilities. These findings highlight the need for improved communication, problem-solving skills, and the implementation of modern teaching technologies. Additionally, this study highlights the complexities of training Japanese perfusionists and underscores the need for more practical, technology-driven educational methods. Addressing these issues is crucial for improving Japan's healthcare standards and could influence global perfusionist education.

Outcome of novel combination of graphene nanoparticles and Moringa methyl ester fueled engine working under varying loads and compression ratios

The widespread use of petroleum products in modern times has led to a search for alternative resources. Biofuel is a promising alternative to petroleum fuel, but biodiesel has a lower calorific value and is slightly more denser than diesel. To address this, a novel combination of GNA emulsified MME20 fuel is being investigated. This study aims to analyze the impact of a novel Nano additive blended biodiesel on engine performance and optimize the best compression ratio for the selected blend. The novelty of the study lies in the production of novel GNA emulsified MME fuel and its influence on a conventional CI engine. To achieve the objectives of the study, MME was produced using a two-phase transesterification method, and GNA was added to the MME20 at concentrations of 30, 60, and 90 ppm using the ultrasonication method. Engine experiments were then conducted using the prepared samples at CRs of 16, 17.5, and 19, and the results were compared with the standard diesel and MME20 blend. The results showed that the CP of the MME20 + GNA30 fuel at a CR 19 revealed a 14% increase compared to diesel. The ID of the fuel decreased by 20% compared to diesel at CR19, and there was a 23.5% increase in the CD for the MME20 + GNA30 blend compared to diesel at CR19. The BTHE for the MME20 + GNA30 fuel showed increases of 2.64% and BSFC and EGT decreases of 3.6% and 3.9%, respectively, at CR19 compared to the other blends. In summary, the study found that MME20 with GNA30, along with VCR, significantly enhanced the engine attributes compared to the pure diesel-operated standard CI engine conditions.

LOGICAL-PROBABLIC MODELING OF FAILURES OF GEODESIC NETWORKS

The credibility and reliability of the results of geodetic and cadastral works depends mainly on the accuracy of the instruments, the qualification of the observer, his professionalism and the reliability of the points of the geodetic network (GN). As a rule, in most cases, there is a well-founded choice of geodetic tools suitable for accuracy and the involvement of a highly qualified geodetic engineer to perform certain types of geodetic work. However, certain questions may arise regarding the determination of starting points for the creation of a reliable geodetic survey justification. The issue of selecting reliable geodetic points for performing engineering and geodetic works based on the application of reliability assessment methods is an urgent scientific problem today. The purpose of the work is to establish the optimal reliability assessment method based on the analysis of existing ones. Adapt this method to solve the problem of assessing the reliability of geodetic networks as one of the most important parameters characterizing its condition. Assess the reliability of the Dnipro geodetic network by constructing a fault tree. Calculate the dynamics of the intensity of GN failures during the 100-year period of its existence. Calculate the appropriate periodicity of surveys (monitoring) of GN depending on the intensity of failures of elements (geodetic points). Methodology. Analysis of international and national standards for reliability assessment, Standards of Ukraine, where the methods of system reliability assessment are given. Review of methods for assessing GN reliability. The deductive method with the construction of a geodetic network failure tree has been applied. This method is based on a logic-probabilistic model of cause-and-effect relationships of system failures with failures of its elements and other events. Scientific novelty. The optimal method of assessing the reliability of GN has been established. A GN failure tree has been built in the TopEvent FTA software tool. The reliability of the geodetic network has been evaluated, the intensity of failures at various stages of its operation has been calculated. Mathematical expressions of the failure functions of the geodetic network have been described by applying Boolean functions. Practical value. International and national regulatory documents and Standards of Ukraine of reliability assessment have been analyzed. In Standarts the methods of system reliability assessment have been given. The performed assessment of the reliability of the state of the geodetic network of the city of Dnipro helps to choose stable geodetic points for the creation of local geodetic networks and survey justification. Reasonable periodicity of monitoring for the survey of geodetic points has been substantiated. The use of reliable points of geodetic networks will allow obtaining reliable observation data, which will significantly increase the quality of engineering and geodetic works. Results. The functioning of the geodetic network of the city of Dnipro on the constructed sequential tree of failures has been considered. Boolean functions to describe the mathematical expressions of the failure functions of the geodetic network, which includes 5 and 10 elements have been used.

Design Of Overheat Detection Device On Vehicle Engine Through Monitoring Water Temperature Or Cooling Oil

Currently, there is a cooling system in vehicle engines that uses additional cooling which warns the driver that the engine's working temperature has exceeded a predetermined threshold, but not for older vehicles or those that still use a CDI (Capacitor Discharge Ignition) system that only relies on the cooling system. through the fins on the machine. To overcome the problems described previously, research was carried out. The result of this research is a tool or device that can detect excessive heat in a vehicle engine using the DS18B20 sensor. The temperature sensor results are processed using an NodeMCU ESP8266 Lolin microcontroller to obtain information about engine temperature. This tool provides a warning system with fan commands and an LCD display that shows the condition of the engine's working temperature at that time. With this tool, overheating of the engine can be prevented.

What Makes this Lesson Engineering? What Makes it Science? Examining the Thought Processes of Pre-Service Elementary Teachers

ABSTRACT Elementary teachers are navigating a curriculum landscape in which engineering activities now exist alongside science. Teacher education should prepare future elementary teachers to be critical curators of curriculum resources, which includes appraising the extent to which engineering and science activities authentically reflect those fields. To date, though, research has not examined how teachers think about what makes a lesson “engineering” rather than “science.” In this study, we examine how a group of elementary pre-service teachers (PSTs) determined the extent to which a set of classroom activities represented engineering and/or science instruction. PSTs analyzed a set of lessons before and after completing an online module that was designed to expand their understanding of the nature of engineering. The module gave PSTs examples of real-world engineering work, drew distinctions between science and engineering, and modeled how those ideas can be applied to instructional decision-making. We found that PSTs identified lessons as “science” when students were conducting investigations and collecting data while learning disciplinary content. In contrast, PSTs saw engineering activities as ones that involved students constructing physical products while solving practical problems. After completing the online module, PSTs placed less emphasis on the “making” of products and more on cognitive aspects of engineering problem-solving, such as testing ideas and justifying design decisions. Our results indicate how teachers’ understanding of the natures of engineering and science can play a role in how they think about what makes an activity “engineering” and/or “science.”

Pengaruh Penambahan Surfaktan Estolida dan Digliserida pada Pelumas Minyak Goreng terhadap Temperatur Mesin dan Daya

Lubricating oil is a type of fluid needed by a machine to carry out work steps. Significant changes in the temperature of the lubricating oil viscosity until it is too low makes the engine components less lubricated, which causes the engine components to heat up quickly because the friction between the metals that occurs becomes greater. Lubricant that is of poor quality can cause deposits to appear in the engine room which results in the engine working harder. The aim can be achieved in this research by varying the lubricating oil with a mixture of Estolide and Diglyceride surfactant percentages of (2.5%, 5% and 7.5%). This test was carried out on a petrol motorbike with a combustion chamber volume of 125cc with standard conditions. The data that will be taken in this research includes engine temperature and power. The power testing method using a dynamometer and lubricant with cooking oil mixed with 7.5% estolide surfactant after heating produces an average value of 6.52 HP which has a higher average value than oil with a value of 5.37 HP

Application of Machine Learning Algorithms to Analyze the Clinical Characteristics of NIHL Caused by Impulse Noise and Steady Noise.

Occupational hearing loss of workers exposed to impulse noise and workers exposed to steady noise for a long time may have different clinical characteristics. As of May 2019, all 92 servicemen working in a weapon experimental field exposed to impulse noise for over 1 year were collected as the impulse noise group. As of Dec 2019, all 78 servicemen working in an engine working experimental field exposed to steady noise for over 1 year were collected as the steady noise group. The propensity score matching (PSM) model was used to eliminate the imbalance of age and working time between the two groups of subjects. After propensity score matching, 51 subjects in each group were finally included in the study. The machine learning model is constructed according to pure tone auditory threshold, and the performance of the machine learning model is evaluated by accuracy, sensitivity, specificity, and AUC. Subjects in the impulse noise group and the steady noise group had significant hearing loss at high frequencies. The hearing of the steady noise group was worse than that of the impulse noise group at speech frequency especially at the frequency of 1 kHz. Among machine learning models, XGBoost has the best prediction and classification performance. The pure tone auditory threshold of subjects in both groups decreased and at high frequency. The hearing of the steady noise group at 1 kHz was significantly worse than that of the impulse noise group. XGBoost is the best model to predict the classification of our two groups. Our research can guide the prevention of damage caused by different types of noises.

Experimental study on the comparative performance of R1233zd(E) and R123 for organic rankine cycle for engine waste heat recovery

ABSTRACT The organic Rankine cycle (ORC) is an effective way for engine waste heat recover (WHR). The selection of the working fluid is crucial. In recent years, low GWP and ODP working fluid have been invented. For R123, which is commonly used in engine ORC-WHR system, the alternative working fluid is R1233zd(E). In order to explore the performance of R123 and R1233zd(E) when applied to ORC-WHR system, this study conducted experimental studies of R123 and R1233zd(E) under a wide range of engine working conditions. The experiments were carried out under seven sets of engine working conditions with gradually increasing loads. Variable operating parameter experiments were carried out for R123 and R1233zd(E) at each engine load. The selected operating parameters include expander speed and superheat degree. The experimental results show that R123 has higher output power and thermal efficiency compared to R1233zd(E) at all engine conditions.The maximum output power and thermal efficiency of R123 are 1.55 kw and 5.81% respectively.The maximum output power and thermal efficiency of R1233zd(E) are 1.43 kw and 5.29% respectively. Taking the net output power as the evaluation index, the optimal expander speed of R123 is higher than that of R1233zd(E) under the same engine working condition, and the superheat degree has little effect on the net output power.

Drying time of plaster within in-fill plasterboard walls and evaporation theory for water within gypsum: methodology, numerical simulation and application

ABSTRACT The desulphurisation-gypsum-filling-wall (DSG-FW) formed by pouring into plasterboard partitions with desulphurisation gypsum slurry can utilise low-quality desulphurisation gypsum and also improve the acoustic insulation issues arising from the use of hollow partitions. The construction schedule of this wall is unable to be controlled because the moisture transfer characteristics in DSG-FW are unclear. Therefore, it is important to determine the drying time and the moisture-transfer behaviour during the construction process. By using different thicknesses of gypsum samples, adding different amounts of perlite and adjusting the relative humidity, whether the gypsum board is covered, the drying and evaporating process of gypsum was compared and analysed. The evaporative characteristics of the desulphurisation gypsum core wall at different relative humidities were determined through experiments. In addition, an evaporation model was introduced for simplification and verification. The experimental results show that the drying of gypsum is correlated with relative humidity and gypsum thickness: the higher the relative humidity, the lower the evaporation rate; the thicker the gypsum, the longer the drying time; perlite and gypsum board have no effect on gypsum drying. The rate of evaporation of DSG-FW increases non-linearly with the decrease in relative humidity under which the DSG-FW is conditioned; the simplified Hertz-Knudsen-Langmuir (HKL-S) model can only be used to predict the evaporation behaviour within the higher relative humidity range (more than 55% RH), while the simplified statistical rate theory (SRT-S) model was verified as being able to predict the rate of evaporation across almost the whole relative humidity range. The SRT-S model can be used to predict and control the construction of DSG-FW in actual engineering work.

Numerical Investigation of the Operating Characteristics of the Passive and Active Prechamber Jet Ignition in a Natural Gas Engine.

Prechamber jet ignition is a promising technology that enables stable ignition and fast combustion by combining thermal effects, chemical kinetics, and turbulent disturbance. The development and application of the prechamber ignition require a comprehensive and in-depth understanding of the operating characteristics of the prechamber ignition in the real engine working cycle. Therefore, numerical simulations are conducted to explore the operating performance of the prechamber ignition applied to a large-bore natural gas engine in this study. The differences between the passive prechamber (PPRE) and active prechamber (APRE) near the lean burn limit are compared. The results show that the jet ignition performance of the PPRE is hampered by the high residual gas coefficient and lean mixture in the prechamber under lean burn conditions. The ignition mode of the PPRE is similar to torch ignition, and the combustion process in the main chamber is mainly turbulent flame propagation. The ignition mechanism of the APRE is flame jet ignition. The main chamber combustion process presents a two-stage heat release characteristic, which can be subdivided into three phases: the initial flame development phase, the rapid combustion phase, and the late combustion phase. The heat release rate during the initial flame development phase depends on the physical and chemical properties of the prechamber jet and the mixture conditions in the main chamber. During the rapid combustion phase, the flame propagation along the radial direction of the jet largely depends on the time scale of the chemical reaction. The heat release rate depends on the coverage area of the jet, the jet residual momentum, and the turbulent flame speed. During the late combustion phase, the flame propagation is mainly affected by the turbulent flame speed. These results provide theoretical guidance for the subsequent application of prechamber ignition systems in various powertrains.

An engineering design-based mathematics activity example based on STEM approach in middle school: Cold storage design

Engineering design practices in STEM education focus on reflecting the discipline-specific work of engineers in a manner that is suitable for the student level and course learning objectives. Using an engineering design context also facilitates student identification of global problems and feasible solutions to address such problems. In this article, within the framework of STEM approach, an engineering design activity that can be applied in middle school mathematics course is presented. Additionally, examples of students’ experiences of the engineering design-based mathematics activity are given. The "Cold Storage Design Activity" was executed in a classroom setting, and the implementation process underwent examination and evaluation. 12 eighth-grade students from a middle school in Turkey took part in the implementation. The middle school were able to successfully perform an engineering design process and effectively overcome challenges through teamwork. The results of the activity show that middle school students are excited and eager to participate in a design activity.

Managing professional socialization of women in engineering and technical work: challenges and solutions

The article explores the management of professional socialization of women in the engineering and technical fields, an important aspect in the context of global efforts towards achieving gender equality and sustainable development. In the face of socio-political instability and considering the adoption of the National Strategy for Action in the Interests of Women for 2023-2030, this topic is particularly significant for Russia. The study aims to analyze the problems and challenges faced by women in the engineering and technical sectors and to identify effective measures to support their professional socialization. The research is based on biographical interviews with female educators (N=19, 2019) and practicing engineers, as well as expert interviews with university representatives (N=25, 2024) and document analysis. The study identified two main issues: limited involvement of women engineers in research activities and gender inequality, along with limited career opportunities for women in this field, which is often characterized by an organizational environment that does not fully adhere to gender equality principles. Key challenges in achieving gender equality in the engineering and technical sectors have been identified, including ensuring equal conditions for women's professional growth and overcoming persistent gender stereotypes about their professional roles and capabilities. Solutions proposed include measures to increase women's involvement in research and support their professional development, as well as creating favorable conditions for career advancement in the engineering and technical fields.

Barclay Curle & Co. Ltd, Britain’s First Ocean-going Motor Ship, MS Jutlandia, and the Scottish Shale Oil Industry

This article explores the link between the building of the pioneering motor ship Jutlandia by Barclay Curle & Co. Ltd in 1912 for the East Asiatic Company of Copenhagen and the Burmeister & Wain oil engines which powered it, notably through Scottish shale oil. It traces the difficulties in building and installing machinery that was unfamiliar to Clydeside engineers and the impact that the ultimate success of the vessel had on marine engine building on the Clyde. After the Burmeister & Wain licence was awarded to Harland and Wolff, the North British Diesel Engine Works was created as a joint venture between Barclay Curle and Swan Hunter, brokered by the oil and shipping broker Frederick Lane and financed by oil industry capital. Despite early promise, the First World War and state control of the shale oil industry hampered the wholesale adoption of shale oil fuelled commercial motor shipping.

Simulation and verification of cylinder head’s temperature field for marine low-speed engine

Abstract The high load capacity of marine low-speed engines poses a challenge to the thermal load of the cylinder head and temperature field simulation can guide its structural design and optimization. The 3-dimensional models of the fluid domain for the cooling water and the solid domain for the cylinder head are established and meshed, the fluid domain model is simulated to research the heat transfer pattern by Fluent software, and the surface temperature and heat transfer coefficient of the cooling water is calculated. The thermal boundary conditions of the gas in the cylinder are simulated through the analysis of the engine working process. The temperature of the cylinder head is calculated based on the fluid-structure interaction model with the thermal boundary conditions by Workbench software. The validation of the model is carried out by comparing the simulated and measured temperature data in the heated inner wall of the cylinder head. The research results show that compared with the measured value, the error of simulation results is small, which shows that the model and method are reasonable. The temperature in the inner wall of the combustion chamber is low, which can provide possibilities to appropriately improve the power density of the low-speed engine and reduce the risk of low-temperature corrosion.

EVALUATION OF GLOBAL GEOPOTENTIAL MODELS IN KAZAKHSTAN BASED ON GEOID HEIGHTS AND GRAVITY ANOMALIES

Orthometric height is required for all surveying work in civil engineering. The most effective and less labor-intensive method for determining orthometric heights on the ground is the use of GNSS technologies. But to use GNSS technologies, it is necessary to determine the geoid height (the difference between ellipsoidal and orthometric heights). This article reviews and compares the latest high-resolution Global geopotential models (GGM) in order to select the optimal model for creating a model of the geoid of Kazakhstan. The study consists of three stages. In the first stage, the GGMs were evaluated using 112 GNSS/leveling points distributed over the test area. In the second stage, selected GGMs were evaluated based on gravity data. In the third stage, some of the best performing models were further compared using spectral information contained in their spherical harmonic coefficients. The EIGEN-6C4 model demonstrated advantages over other GGMs (XGM2019e_2159, GECO, SGG-UGM-2, EGM2008) that participated in the accuracy assessment, showing a standard deviation of 0.267 m at the first stage. When analyzed to match ground-based gravity data, the EIGEN-6C4 model demonstrated a match with a standard deviation of 5.341 mGal. Based on the evaluation results, it is decided that EIGEN-6C4 is the most suitable model for generating local geoid, which will contribute to the development of geodesy in civil engineering in the future.

A quantum otto heat engine driven by three quantum dots

A quantum heat engine composed of three coupled quantum dots as a working substance is proposed. Since quantum dots naturally obey the Fermi Hubbard Hamiltonian, the strong coupling interaction regime allows the working substance to be evaluated under an effective Heisenberg Hamiltonian. Indeed, the influence of the strength coupling, between the three dots, on quantum machine efficiency and work in the presence of a homogeneous magnetic field is also examined. Furthermore, the influence of entanglement on the efficiency & work of the quantum dot Otto heat engine is well analyzed. As a tripartite working substance, we are interested in analyzing the local work and efficiency associated with each single and pair of quantum dots. The results show that the local efficiency associated with a pair of quantum dots achieves a maximum value, unlike the global efficiency. Indeed, the entanglement impact on Global/local work is studied.