Correct Operation Research Articles

Long-term results of operations for hernias of the esophageal orifice of the diaphragm depending on the performance of vagotomy

Introduction. Hernia of the esophageal orifice of the diaphragm, complicated by reflux esophagitis, is one of the most common gastroenterological diseases, occupying the first place among all benign pathology of the cardiofundal zone. Typical complications of this pathology are esophagitis of varying severity, bleeding from the esophagus, peptic stricture and shortening of the esophagus, Barette's esophagus, ulcer and cancer of the esophagus. Indications for surgery include severe reflux esophagitis, the development of complications, and the failure of conservative therapy.Objective: to evaluate the effect of stem vagotomy on the long-term results of surgical treatment of patients with hiatal hernia complicated by reflux esophagitis.Object and methods. The long-term treatment outcomes of 130 patients were studied. All patients had increased acid production. The patients were divided into two groups: group I – 77 patients who underwent correction of hiatal hernia in isolation; group II – 53 patients who had correction of hiatal hernia supplemented by stem vagotomy. In group I, anatomical recurrence of hiatal hernia was diagnosed in 14 patients (18.2%), and in group II – in 1 (1.9%) patient. In the long-term postoperative period, none of the patients who underwent stem vagotomy were diagnosed with severe reflux esophagitis. While in patients who did not undergo stem vagotomy, a severe form of reflux esophagitis was found in 10.3% of patients.Conclusion. In patients with hiatal hernia with increased acid production complicated by reflux esophagitis, it is advisable to supplement the correction operation with a stem vagotomy. This tactic leads to a statistically significant decrease in the number of relapses in the long-term period.

Gas equilibrium membrane inlet mass spectrometry (GE-MIMS) for water at high pressure

Abstract. Gas species are widely used as natural or artificial tracers to study fluid dynamics in environmental and geological systems. The recently developed gas equilibrium membrane inlet mass spectrometry (GE-MIMS) method is most useful for accurate and autonomous on-site quantification of dissolved gases in aquatic systems. GE-MIMS works by pumping water through a gas equilibrator module containing a gas headspace, which is separated from the water by a gas-permeable membrane. The partial pressures of the gas species in the headspace equilibrate with the gas concentrations in the water according to Henry's Law and are quantified with a mass spectrometer optimized for low gas consumption (miniRUEDI or similar). However, the fragile membrane structures of the commonly used equilibrator modules break down at water pressures ≳3 bar. These modules are therefore not suitable for use in deep geological systems or other environments with high water pressures. To this end, the SysMoG® MD membrane module (Solexperts AG, Switzerland; “SOMM”) was developed to withstand water pressures of up to 100 bar. Compared to the conventionally used GE-MIMS equilibrator modules, the mechanically robust construction of the SOMM module entails slow and potentially incomplete gas–water equilibration. We tested the gas equilibration efficiency of the SOMM and developed an adapted protocol that allows correct operation of the SOMM for GE-MIMS analysis at high water pressures. This adapted SOMM GE-MIMS technique exhibits a very low gas consumption from the SOMM to maintain the gas–water equilibrium according to Henry's Law and provides the same analytical accuracy and precision as the conventional GE-MIMS technique. The analytical potential of the adapted SOMM GE-MIMS technique was demonstrated in a high-pressure fluid migration experiment in an underground rock laboratory. The new technique overcomes the pressure limitations of conventional gas equilibrators and thereby opens new opportunities for efficient and autonomous on-site quantification of dissolved gases in high-pressure environments, such as in research and monitoring of underground storage of CO2 and waste deposits or in the exploration of natural resources.

Improved Feedback Quantizer with Discrete Space Vector.

The use of advanced modulation and control schemes for power converters, such as a Feedback Quantizer and Predictive Control, is widely studied in the literature. This work focuses on improving the closed-loop modulation scheme called Feedback Quantizer, which is applied to a three-phase voltage source inverter. This scheme has the natural behavior of mitigating harmonics at low frequencies, which are detrimental to electrical equipment such as transformers. This modulation scheme also provides good tracking for the voltage reference at the fundamental frequency. On the other hand, the disadvantage of this scheme is that it has a variable switching frequency, creating a harmonic spectrum in frequency dispersion, and it also needs a small sampling time to obtain good results. The proposed scheme to improve the modulation scheme is based on a Discrete Space Vector with virtual vectors to obtain a better approximation of the optimal vectors for use in the algorithm. The proposal improves the conventional scheme at a high sampling time (200 μs), obtaining a THD less than 2% in the load current, decreases the noise created by the conventional scheme, and provides a fixed switching frequency. Experimental tests demonstrate the correct operation of the proposed scheme.

Effect of Time-Varying Multiplicative Noise on DNN- k WTA Model.

Among many k -winners-take-all ( k WTA) models, the dual-neural network (DNN- k WTA) model is with significantly less number of connections. However, for analog realization, noise is inevitable and affects the operational correctness of the k WTA process. Most existing results focus on the effect of additive noise. This brief studies the effect of time-varying multiplicative input noise. Two scenarios are considered. The first one is the bounded noise case, in which only the noise range is known. Another one is for the general noise distribution case, in which we either know the noise distribution or have noise samples. For each scenario, we first prove the convergence property of the DNN- k WTA model under multiplicative input noise and then provide an efficient method to determine whether a noise-affected DNN- k WTA network performs the correct k WTA process for a given set of inputs. With the two methods, we can efficiently measure the probability of the network performing the correct k WTA process. In addition, for the case of the inputs being uniformly distributed, we derive two closed-form expressions, one for each scenario, for estimating the probability of the model having correct operation. Finally, we conduct simulations to verify our theoretical results.

Simplified Single-Stage Buck-Boost Rectifier With Proportional-Integral and Cascaded Proportional-Resonant Control Method

This paper presents a simplified single-stage buck-boost rectifier as well as a proportional-integral (PI) and cascaded proportional-resonant (PR) control methods. The design of the proposed rectifier is based on a recently introduced buck-boost inverter with the elimination of low-frequency switches in the H-bridge. It is verified that the low-frequency switches are redundant, and the rectifier can operate when these switches are replaced with diodes. Elimination of four switches as well as their drivers not only simplifies the modulation scheme, but also reduces the overall cost of the proposed rectifier. Moreover, the proposed PI and cascaded PR control method ensures almost zero steady-state error in the dc-link voltage as well as in the grid current. The correct operation of proposed rectifier together with the proposed control method during buck and boost modes are confirmed with experimental results obtained from a 500W prototype. The steady-state and transient results are obtained to verify that the proposed rectifier has a wide ac grid voltage and dc-link voltage operation ranges.

A Three-Transistor Energy Management Circuit for Energy-Harvesting-Powered IoT Devices

Energy harvesting (EH) provides a promising solution for powering distributed Internet of Things (IoT) devices. Due to the low-level and sporadic ambient energy supply, an EH-powered device should operate in an intermittent and energy-driven mode. Commercial voltage supervisors were not optimized for the EH scenario, making it difficult to satisfy all new demands. The conventional energy management (EM) circuit has a risk of locking up during the turn-on transient; therefore, it might fail to power the IoT load device. Previous technologies have used a relatively large circuit to solve this problem. In this paper, a concise discrete three-transistor energy management circuit (3T-EM) is proposed. It can track stored energy, switch on/off to the load device, and provide a regulated voltage output. These key functions are realized by utilizing a minimum number of components; therefore, power consumption and manufacturing cost are largely cut. The voltage thresholds and minimum input current are theoretically derived. In experiments, the on/off thresholds can be adjusted accurately, as predicted by the theory. The 3T-EM circuit can ensure the correct operation when the input current is as low as 0.4 μA. Control experiments also prove the effectiveness and performance of the 3T-EM circuit. The proposed 3T-EM circuit shows the characteristics of low cost, low power, inherent regulation, high voltage rating, and good predictability. It is a good candidate to perform the EM task in widely distributed EH-powered IoT devices.

OPTIMALISASI LAHAN BUDIDAYA PERTANIAN DENGAN SYSTEM MULTICROPPING SEBAGAI AGROWISATA EDUKATIF DI WONOGIRI

Indonesia is an agricultural country where the agricultural sector plays an important role in supporting national economic growth in the era of globalization, Land is one of the important indicators for the agricultural process, the effectiveness of land in each region is different. This study aims to describe the development of optimization of agricultural cultivation land with the Multiple Cropping system. The purpose of this optimization is the combination of cultivation of food crops and horticultural crops or called integrated agriculture on a certain economic scale, the cultivation process needs to be carried out with the correct technology support pattern and Standard Operating Procedure (SOP). This research uses qualitative research methods. Data collection techniques using interviews, observation and documentation. Data analysis uses qualitative descriptive analysis techniques. This study was conducted at Barro Tani Manunggal Agritourism. The results of this study show that land optimization techniques with multiple cropping systems are very effective to be applied in various land conditions, and can also be a business field for farmers.

Sizing of a Scattered Housing Microgrid in a Remote Rural Area

Power solutions for remote rural regions are mainly based on generator sets or individualized generation systems per household. These solutions have low reliability and high financial and environmental costs, especially those involving fossil fuels. However, current solutions incorporate hybrid systems with renewable energy sources to reduce pollutant gas emissions and costs and increase the reliability and robustness of power generation. These hybrid systems can be considered micro-grid (MG) and could contribute to energizing remote non interconnected areas. However, implementing MGs in these regions must challenge energizing dispersed households. Thus, both the sizing of the generation and distribution systems must be considered to guarantee the correct operation of the MG and a low cost. This paper explores coordinated sizing between the power sources and the distribution system to address the challenges of energizing remote areas with dispersed loads through MG. It presents a literature review on energization strategies for remote regions and proposes coordinated MG sizing. Finally, it applies coordinated sizing to a case study in Colombia. The sizing is approached as a mixed-integer nonlinear integer programming optimization problem and is solved by a particle swarm optimization (PSO) algorithm.

A study on the application of Prepar3D-based Aviation’s Localizer Performance with Vertical Guidance Approach procedures in the teaching of simulated flight training courses

Firstly, the advantages of flight simulators and the three types of flight simulation software widely used by current flight students are briefly described, focusing on the analysis of instrument landing knowledge, how to read the instrument approach procedure charts, and how to use the flight simulation software to implement various instrument landing systems, so as to make the correct operation according to the approach procedure charts. Based on Prepar3D flight simulation software, Cessna C172R G1000 system was used to demonstrate two different types of precision approaches, so that the trainees could be more clearly and intuitively familiarized with the relevant operation procedures of precision approaches. From the results of the demonstration, it can be seen that flight simulation has the advantages of improving training efficiency, saving training funds, ensuring flight safety, and reducing environmental pollution, etc. The advantages of flight simulation software can fundamentally improve the flight skills of the trainees, increase flight experience, and thus reduce the incidence of major safety accidents.

Developing typical profiles of generation Z students to improve the quality of the educational process

Global digital platforms that influence the development of local digital platforms (from national-level platforms to the platform of a particular enterprise), in order to be more effective, must take into account the informational requirements of users, including those determined by their emotional and psychological characteristics. For this purpose, their developers need to know the typical emotional and psychological profiles of users.The construction of typical emotional and psychological profiles of Generation Z learners is necessary for correct and efficient operation of information and educational platforms, in particular, adaptive e-learning environments, which, among other things, implement gamification approaches.To identify the above-mentioned profiles of Generation Z learners, we use R. Cattell’s multifactor testing methodology (form C) and subsequent processing of the obtained results using statistical methods (in the form of cluster analysis). To ensure the representativeness of the results, the study involved 994 students from various universities (the survey results were used in an impersonal form).The analysis of clustering results makes it possible to identify the share of students who are able to independently form new knowledge and obtain original results of intellectual activity, to determine the share of students with a pragmatic attitude to life, as well as those who possess the qualities of business leadership, etc.Based on these results, recommendations for improving the quality of the educational process as a special case of adaptive e-learning environment are formulated.

РАСПОЗНОВАНИЕ ДЕФЕКТОВ ЛОПАТОЧНОГО АППАРАТА ТУРБОМАШИН ПРИ ПОМОЩИ НЕЙРОННОЙ СЕТИ

Correct, serviceable and high-quality operation of a turbomachine directly depends on the condition of its flow path. One of the reasons for the decrease in the efficiency and reliability of the turbine unit is the wear of the blade apparatus due to the formation of various defects on the edges and surface of the blade airfoil. This study develops an approach to automating the defect detection process of products using modern computer vision technologies. In this work, a program code was prepared in the Python programming language, a database of images of blade defects was created, and the YOLOv8 model was trained and tested. The achieved accuracy in determining the type of defect in the study exceeded 80%.

Small Scale Models of Solar Tracking Systems

Increasing the efficiency of photovoltaic panels using solar tracking systems is a current topic. The use of solar tracking systems is a solution, especially in low power applications. The paper presents two types of solar tracking systems, one based on astronomical data, and the other based on tracking the point of maximum illumination. Both systems are made on small scale for educational purposes. These systems can be used for the analysis of methods, principles and particularities in order to use them in practical applications. For the two experimental models of solar tracking made, the hardware and software structure are presented. To orient the photovoltaic panels in the two directions (East-West, respectively South-North) DC motors or stepper motors are used. One motor is used for each axis of rotation. Both structures have the control part composed of a microcontroller development system. This control method has the advantage that can significantly reduce the number of electronic components as well as the cost of designing and building of equipment. For the solar tracking system based on astronomical data, a remote monitoring and control system has been achieved. It uses a friendly graphic interface made on PC with the help of Visual Basic software. Both models were tested and the experimental results showed correct operation according to the imposed protocol. Finally, an energy efficiency analysis was done and it was found that the PV panel that uses the tracking systems produces 35% more energy compared to a fixed PV panel.

Surface Functional Modification for Boosting Power Density of Hydrovoltaic Devices

AbstractGenerating electricity based on the interaction between water and materials is a new green energy harvesting technology. However, the performance based on streaming potential generation is not sufficient to drive microelectronic devices with high power supply demands. In this work, an asymmetric sandwich structure is designed with adjustable performance of hydrovoltaic devices as a power system for micro‐electronic devices. The flexible hydrovoltaic device structure that only consumes renewable energy is low‐cost, non‐polluting, and highly sustainable, achieving a satisfied output power density exceeding 124.5 µW·cm−2 (2075 µW·cm−3). Both experimental results and theoretical calculations reveal that the working principle of the device depends on the evaporation potential rather than the streaming potential. In addition, the integration of multiple devices makes it easy to drive electronic devices for correct operation and energy storage. For the first time, this integrated hydroelectric photovoltaic device has demonstrated the ability to charge commercial button‐type lithium batteries with great success. The current work combines asymmetric structure and tunable performance, providing an alternative method for high‐efficiency hydrovoltaic devices with high power density.

Modelling the Reliability of Logistics Flows in a Complex Production System

This paper analyses the disruptions occurring in a production system determining the operating states of a single machine. A system with a convergent production character, in which both single flows (streams) and multi-stream flows occur, was considered. In this paper, a two-level formalisation of the production system (PS) was made according to complex systems theory. The continuity analysis was performed at the operational level (manufacturing machine level). The definition of the kth survival value and the quasi-coherence property defined on chains of synchronous relations were used to determine the impact of interruption of the processed material flow on uninterrupted machine operation. The developed methodology is presented in terms of shaping the energy efficiency of technical objects with the highest power demand (the furnace of an automatic paint shop and the furnace of a glass tempering line were taken into consideration). The proposed methodology is used to optimise energy consumption in complex production structures. The model presented is utilitarian in nature—it can be applied to any technical system where there is randomness of task execution times and randomness of unplanned events. This paper considers the case in which two mutually independent random variables determining the duration of correct operation TP and the duration of breakdown TB are determined by a given distribution: Gaussian and Gamma family distributions (including combinations of exponential and Erlang distributions). A formalised methodology is also developed to determine the stability of system operation, as well as to assess the potential risk for arbitrary system evaluation parameters.

Flow-Thermal-Strength Analysis of the Finned Tube Heat Exchanger Operation

Ensuring the safety and adequate service life of thermal power equipment, in addition to the need to maintain the required operating parameters, are among the most important issues related to the heat exchanger operation. This also applies to heat exchangers with extended surfaces, which are usually achieved by finned tubes. They are typically used where heat is exchanged between working fluids characterized by quite different properties, such as gas-water or air-coolant fluids. The high parameters of these fluids (temperature, pressure), occasionally their aggressiveness, and often the salts they contain, causing fouling of surfaces, can be the cause of failures. Among the most common are tube failures, which can lead to severe consequences. The developed methodology of coupled flow-thermal and strength analysis was used in exemplary calculations for a two-pass, two-row combustion gas - water heat exchanger with finned elliptical tubes. The reason for choosing such a design, was the fact of having failure data for two similar designs. This allowed verification of the correct operation of the developed methodology and redesign the heat exchanger manifold to ensure better flow distribution in a tubular space and better stress distribution.

Transverse Profiles of Belt Core Damage in the Analysis of the Correct Loading and Operation of Conveyors

This article presents an analysis of the transverse profile of belt damage in the context of the proper loading and operation of conveyors. The aim of this study was to identify and understand the characteristic features of damage and their placement that may occur in conveyor belts during operation and indicate abnormalities in any of the components of the conveyor system, especially during loading at chutes. A total of seven different conveyors were examined, and the obtained results allowed for a thorough comparison and investigation of the distribution of belt damage on their cross-sectional profiles. This article discusses factors that may contribute to the occurrence of unevenly distributed belt damage. The conclusions from the conducted research can be of significant importance for conveyor owners and operators as they enable an effective assessment of the conveyor belt’s condition, the correctness of the conveyors, and the chutes’ designs as well as the implementation of necessary design changes, correct actions, and repairs. Through proper belt monitoring and maintenance, the risk of failure can be minimized, extending the belts’ lifespan and ensuring the efficiency of the transportation process. The article presents practical approaches to the analysis of the cross-sectional profile of damage, serving as a valuable source of information for individuals interested in optimizing the transportation process and maintaining efficient and safe conveyor operation.

First operational dodecapole correction in the LHC

First operational dodecapole correction in the LHC

How mechanics of individual muscle-tendon units define knee and ankle joint function in health and cerebral palsy-a narrative review.

This study reviews the relationship between muscle-tendon biomechanics and joint function, with a particular focus on how cerebral palsy (CP) affects this relationship. In healthy individuals, muscle size is a critical determinant of strength, with muscle volume, cross-sectional area, and moment arm correlating with knee and ankle joint torque for different isometric/isokinetic contractions. However, in CP, impaired muscle growth contributes to joint pathophysiology even though only a limited number of studies have investigated the impact of deficits in muscle size on pathological joint function. As muscles are the primary factors determining joint torque, in this review two main approaches used for muscle force quantification are discussed. The direct quantification of individual muscle forces from their relevant tendons through intraoperative approaches holds a high potential for characterizing healthy and diseased muscles but poses challenges due to the invasive nature of the technique. On the other hand, musculoskeletal models, using an inverse dynamic approach, can predict muscle forces, but rely on several assumptions and have inherent limitations. Neither technique has become established in routine clinical practice. Nevertheless, identifying the relative contribution of each muscle to the overall joint moment would be key for diagnosis and formulating efficient treatment strategies for patients with CP. This review emphasizes the necessity of implementing the intraoperative approach into general surgical practice, particularly for joint correction operations in diverse patient groups. Obtaining in vivo data directly would enhance musculoskeletal models, providing more accurate force estimations. This integrated approach can improve the clinicians' decision-making process and advance treatment strategies by predicting changes at the muscle and joint levels before interventions, thus, holding the potential to significantly enhance clinical outcomes.

A semi-Lagrangian Splitting framework for the simulation of non-hydrostatic free-surface flows

Incorporation of the free-surface dynamics plays an important role in the numerical modelling of non-hydrostatic flows. In the present work a novel semi-Lagrangian splitting (SLS) scheme for the free-surface Euler system is proposed.Using the operator splitting technique, the three main components emerge: the multilayer Shallow Water Equations (mSWE) (enforcing the free-surface kinematics), the Vertical Remeshing Operator (VRO) (that blends the Eulerian and Lagrangian techniques) and the Pressure Correction Operator (PCO) (that is a classic elliptic equation used in projection-type pressure coupling schemes). The first two are solved by two separate Finite Volume schemes, while the latter is resolved in a Finite Difference manner.In order to assess the SLS’s performance, numerical simulations of periodic waves and solitons propagating over variable bathymetry are performed. The last case concerns the propagation of waves on top of a shear current, showcasing the use of the SLS on rotational flows. The results are compared with experiments and analytic relations and the method is proven to be robust and efficient.

Code observation-specific biases estimation for the modernized multi-GNSS and multi-frequency signals: An approach considering signal distortion biases

With the continuous development of global navigation satellite systems (GNSS) modernization, the code bias presented in the form of observation-specific biases (OSB) is more flexible and effective when processing modern multi-frequency and multi-GNSS signals, and therefore widely accepted by the GNSS community. However, the newly reported signal distortion biases (SDB) are ignored in the existing OSB estimation methods, which may affect the reliability of the final OSB estimation. In addition, the existing studies about SDB estimation are independent of OSB estimation, and thus a set of SDB products is generated independent of OSB products, which undoubtedly brings more complicated correction operations to GNSS users. In view of it, this study proposes an approach to code OSB estimation for multi-frequency and multi-GNSS arbitrary signals by reparameterization, which considers the SDB parameter. The aim of this study is to generate a set of code OSB products that take into account SDB parameters for the GNSS users to use. Due to considering the influence of SDB on raw code observations, the OSB estimation obtained by the proposed method is related to specific satellite-receiver pairs, which makes it different from the traditional OSB estimation methods. To achieve this, an extended model for multi-frequency and multi-GNSS arbitrary signal is first established based on the undifferenced and uncombined model, in which the SDB parameter is taken into account by re-parameterization. Based on the proposed model, three types of code bias that contain the OSB information can be obtained for the subsequent OSB estimation. Then, the three types of code bias in the first step are used as virtual observations for multi-frequency and multi-GNSS arbitrary signal OSB estimation through a two-step method. The proposed method is validated with a whole month of real measured data from 418 stations in MGEX and GA CORS to generate OSBs for GPS, GLONASS, and Galileo. The comparison between the estimated OSBs and the OSB products from CAS indicates the reliability of the proposed method. Besides, all types of OSB for four receiver groups are generated based on the proposed method to analyze the relationship between OSB and receiver groups. Results indicate that the estimated OSBs are related to receiver groups, and specific differences exist between different satellites and GNSS signals. It also proves that the OSB estimation is biased by the inconsistencies of the deviation in different receiver groups, which is more obvious for GLONASS.