Operation Problems Research Articles

Problems of testing and operation of hydraulic power transfer units

The purpose and principles of operation of a civil aircraft emergency system including a power transfer unit are considered. Problems and trends of the development of piston hydraulic machines in aircraft construction are analyzed. The parameters of power transfer units used on 12 types of passenger airplanes are analyzed. The scenarios of failure of power transmission units are considered. The main directions of solving the problems of operation, as well as the requirements to design and testing are outlined.

Solving optimization problems in steady operation of regulated asynchronous motor

Solving optimization problems in steady operation of regulated asynchronous motor

Identification of transformer overload and new energy planning for enterprises based on load forecasting.

The new energy system constructed by energy storage and photovoltaic power generation system can effectively solve the problem of transformer overload operation in some enterprises. It can not only reduce the cost of electricity, but also realize low-carbon emission reduction. However, due to its low return on investment, the willingness of enterprises to install new energy is not high. In this paper, we first establish a load forecasting model to users whose transformers are overloaded or about to be overloaded, which are potential customers with new energy installation needs. Then, Optimal configuration models of PV and energy storage systems based on nonlinear programming are developed for these potential customers. The optimal installed capacity of the PV energy storage and the optimal charging and discharging strategy for the energy storage system can be obtained. This optimization strategy ensures that the electricity consumption of the enterprise does not exceed the rated capacity, and effectively reduces the enterprise's basic tariff and electricity price to achieve cost reduction and efficiency. Finally, taking a building materials production factory as an example, we obtain the optimal plan for the new energy capacity, as well as the economic benefits of the plan and the specific strategy of energy storage charging and discharging for this factory.

Euler Force-Driven Siphon Valve Control for Precise Sequential Release in Centrifugal Microfluidic Chips

Controlling the fluids in centrifugal microfluidic chips for precise sequential release is critical for multi-step reactions and immunoassays. Currently, the traditional methods of liquid sequential release mainly rely on various types of microvalves, which face the problems of complex operation and high costs. Here, this work presents a method for driving liquid release using the Euler force. Under continuous acceleration and deceleration, the centrifugal and Euler forces can transfer the liquid from the sample chamber to the collection chamber. The liquid sequential release mechanism based on the Euler force was analyzed, which showed that the angular acceleration is key to the liquid release. Then, the geometrical parameters affecting the angular acceleration of complete release were investigated and simulated. Finally, based on the relationship between the geometrical parameters of the connecting channels and the angular acceleration of complete release, a simple and precise sequential release structure was designed, which allowed for a sequential and stable transfer of the liquid into the reaction chamber. The results showed that the proposed method is capable of transferring liquid, and its simple structure, low manufacturing cost, and ease of operation enable precise sequential liquid release in centrifugal microfluidic platforms.

Research on random dynamic cylinder deactivation control strategy of engine based on nonlinear model prediction

In the process of cycle cylinder deactivation, the different proportion of cylinder deactivation between adjacent working cycles will cause the problem of uneven operation of each cylinder. In this paper, a random dynamic cylinder deactivation (RD-CDA) control method based on nonlinear model prediction is proposed. The RBF neural network model of the RD-CDA system is built. The K-means algorithm is applied to the offline training of the center position c of the hidden layer node. The P-nearest algorithm is used to train the hidden layer node width σ offline. The recursive least squares (RLS) algorithm is applied to train the output layer weight vector w online. The online adaptive change of the model is realized, and the model verification is carried out. Then, the nonlinear model predictive control system structures with the minimum torque fluctuation and brake specific fuel consumption rate (BSFC) are built respectively. Under different working conditions, the average torque fluctuation per cycle is improved by about 9% to 18.75%, and the average BSFC is improved by about 2 % -3.9 %, which verifies the effectiveness of this strategy in reducing the dynamic fluctuation of random dynamic cylinder deactivation torque and improving fuel economy.

The Results of the Laboratory Study on the Separating Fiber Flax Seed Balls when Combing the Standing Plants with a Single-Rotor Comb-Dresser

Introduction. The low purity of combing flax seed balls with flax harvesters is a problem for the technological operation when harvesting fibre flax. The analysis of the comb designs of the combing units made it possible to identify the main disadvantages that do not fully meet the agrotechnical requirements for harvesting fiber flax. An innovative design of a removable comb for single-rotor drum-type harvesters is proposed.Aim of the Study. The study is aimed at determining the purity of combing the standing fiber flax stems using a single-rotor comb-dresser with removable combs.Materials and Methods. There has been made an experimental setup to simulate the process of combing standing fiber flax plants with combs of a single-rotor comb dresser. During the period from 2018–2023, the design parameters and operating modes of the combing unit were investigated and justified. There has been developed a technique for conducting a multifactorial experiment to determine the purity of combing fiber flax using a combing drum-type unit with removable combs.Results. The results of laboratory studies on the separating flax balls from the standing fiber flax stems by removable combs are presented to determine the combing quality. It has been found that the purity of combing fiber flax plants is up to 99.2%.Discussion and Conclusion. When studying the technological process of combing Nadezhda standing fiber flax plants the with single-rotor drum removable combs, the physico-mechanical properties of the flax stems were studied in laboratory conditions, the optimal operating modes of the combing drum were determined, which ensure the purity of the stems above 98% that meets the agrotechnical requirements for flax combines.

Some aspects of reliability prediction of chemical industry and hydrogen energy facilities (vessels, machinery and equipment) operated in emergency situations and extreme conditions

This work is aimed at a comprehensive solution to the problem of reliable and safe operation of a transport energy system with a high energy concentration based on a universal energy carrier - cryogenic liquid hydrogen.The article discusses the possibility of using various methods and techniques to assess the reliability of machines and equipment operated in emergency situations and extreme conditions. The obtained results are analyzed.Currently, the oil and gas complex pays great attention to the development of hydrogen technologies, as well as hydrogen energy in connection with the relevance of the Climate Agenda. In this regard, hydrogen energy facilities are of the greatest interest: cryogenic hydrogen reservoirs, cryogenic hydrogen pipelines, cryogenic oxygen reservoirs and cryogenic oxygen pipelines, as well as cryogenic reservoirs and pipelines for storing process nitrogen gas. An important role for global energy exchange is played by LH2 tankers for transporting cryogenic hydrogen. For example, Australia and Japan built the first LH2 tanker to transport hydrogen from Australia to Japan. In addition, another 85 LH2 tankers are expected to be built.After transportation, cryogenic hydrogen is stored in cryogenic hydrogen storages, usually also representing cryogenic hydrogen tanks with piping in the form of cryogenic pipelines, as well as cryogenic nitrogen tanks for storing process nitrogen gas. Further, hydrogen is used in road transport, aviation, ship fleet, industry, and energy. The main elements of mobile, stationary and airborne hydrogen storage systems are under critical loads and are in the area of increased study and attention.In this regard, we considered the functions of changing the main operational characteristics, made proposals on the possibility of predicting the development of accumulated faults and proposals for ensuring safety and extending the life of objects, taking into account the determination of local and integral damage to cryogenic tanks and pipelines.

Robotic Valve Turning with a Wheeled Mobile Manipulator via Hybrid Passive/Active Compliance.

This paper addresses the problems of valve-turning operation in rescue environments where a wheeled mobile manipulator (WMM) is employed, including the possible occurrence of large internal forces. Rather than attempting to obtain the exact position of the valve, this paper presents a solution to two main problems in robotic valve-turning operations: the radial position deviation between the rotation axes of the tool and the valve handle, which may cause large radial forces, and the possible axial displacement of the valve handle as the valve turns, which may lead to large axial forces. For the former problem, we designed a compliant end-effector with a tolerance of approximately 3.5° (angle) and 9.7 mm (position), and provided a hybrid passive/active compliance method. For the latter problem, a passivity-based force tracking algorithm was employed. Combining the custom-built compliant end-effector and the passivity-based control method can significantly reduce both the radial and the axial forces. Additionally, for valves with different installation types and WMMs with different configurations, we analyzed the minimum required number of actuators for valve turning. Simulation and experimental results are presented to show the effectiveness of the proposed approach.

Risk Assessment of Rubber Tapping A Case Study: Pa Phayom District, Phatthalung Province, Thailand

This cross-sectional study investigated the risks of rubber tapping among rubber farmers in Pa Phayom District, Phatthalung Province, Thailand, utilizing the EART (Ergonomic Risk Assessment Tool for Rubber Tappers) and RULA (Rapid Upper Limb Assessment) approaches. Purposive sampling was utilized to randomly choose 154 rubber farmers, aged 20 to 60 to serve as the sample group. They met the inclusion requirements of being in excellent health, being able to read and write Thai fluently, not having a history of back discomfort or injuries, and having at least a year of experience tapping rubber. The results showed that the mean RTL value was 415, SD = 182, while the mean RTI value was 1.77, SD = 1.35, with Min = 0.31 and Max = 8.64. The RULA analysis gave scores ranging from 2 to 7 as acceptable risk to high risk, suggesting that rubber farmers should improve their working posture or reduce factors that affect risk to ensure better health outcomes. It was discovered that the EART and RULA can be used as an assessment method to identify ergonomic risk problems in rubber tapping operation. It was suggested that the rubber tapping operation needs to be improved, re-evaluated, and implemented immediately.

Literature Review on Fresh Products Cold Chain Logistics and Distribution Issues

In this paper, the literature on the concepts of fresh product cold chain logistics, the container operation problems related to cold chain transport, product order picking, distribution and the integration of the two problems are sorted out to provide theoretical references for the further study of the transport and distribution problems of fresh product cold chain logistics. Through combing the literature at home and abroad, the current fresh product cold chain logistics transport and distribution mainly exists in the container intermodal transport research object is single, mostly focusing on the railway container centre station; order distribution problems related research is less, vehicle path problem solving algorithms and related mathematical models are less; order picking and distribution of the joint research is less, and most of them stay in the theoretical stage, the method of landing is more difficult and other problems.

Recent Progress in Memrsitor Array Structures and Solutions for Sneak Path Current Reduction

AbstractMemristors have diverse potential for improving data storage through linear memory control and synaptic operation in AI and neuromorphic computing. Prior research on optimizing memristors in next‐generation devices has generally indicated that emerging arrays and vertical structures can improve memory density, although special fabrication steps are required to realize improved operation. Until now, many obstructions, such as the sneak path current and forming processes from the initial device in array structure operation at the device level, have limited the development of array‐based memristor devices for further progressing circuits and integrated design. In this paper, memristor array studies are examined that have suggested solutions for sneak path current and forming operation problems at the device level. Ultimately, representative solutions are proposed to progress memristors into array structures by introducing the latest research on one diode‐one RRAM (1D1R), one selector‐one RRAM (1S1R), overshoot suppressed RRAM (OSRRAM), self‐rectifying cell (SRC), charge trap memory (CTM) and their applications. Additionally, essential details demonstrating the practical implementation of these devices in crossbar array memory are investigated. Finally, the advantages and perspectives of these array‐based memristor solutions are summarized.

Using An In Vitro Tissue Perfusion System to Detect the Functional Activities of Isolated Intestinal Tubes in Real Time.

Gastrointestinal diseases, which have a high incidence, pose considerable challenges for humans. The small intestine is integral to food and drug digestion and absorption and plays a crucial role in treating these diseases. The intestinal tube movement experiment, a common and essential in vitro method, is utilized to study gastrointestinal dynamics. This includes the preparation of the isolated intestinal tube, as well as the suspension of the prepared intestinal tube in the bath and its connection to a signal detector. This is followed by the recording and analysis of a series of parameters, such as tension, which can be used to assess intestinal motor function, as well as considerations for keeping the intestinal tube active in vitro. The standardized program from sampling to data collection greatly improves the repeatability of the experimental data and ensures the authenticity of the recording of intestinal tension after physiological, pathological, and drug intervention. Here we present the key problems in experimental operation and a valuable reference experimental protocol for studying drugs that regulate gastrointestinal motility.

Research on the Collision Risk of Fusion Operation of Manned Aircraft and Unmanned Aircraft at Zigong Airport.

Low-altitude airspace is developing rapidly, but the utilization rate of airspace resources is low. Therefore, in order to solve the problem of the safe operation of the fusion of large UAVs and manned aircraft in the same airspace, this paper analyzes the theoretical calculation of the collision risk of the fusion operation of manned aircraft and UAVs at Feng Ming Airport in Zigong, verifying that while assessing the safety spacing of 10 km in the lateral direction, it further simulates the possibility of calculating the theoretical smaller safety spacing. The study will propose a new theory of error spacing safety margin and improve it according to the traditional Event collision risk model, combining the error spacing safety margin to establish an improved collision model more suitable for the fusion operation of manned and unmanned aircraft and reduce the redundancy of calculation. The error factors affecting manned and unmanned aircraft at Zigong Airport are analyzed, and theoretical calculations are analyzed by combining the actual data of Zigong Airport. Finally, the Monte Carlo simulation method is used to solve the error, substitute the calculation results, and simulate a section of the trajectory of the fusion operation for the reverse argument. The theoretical calculation results show that the collision risk from 10 km to 8 km satisfies the lateral target safety level (TSL) specified by ICAO under both traditional and improved models. The collision risk calculated by the improved model incorporating the error spacing safety margin is smaller, which enhances the safety of the model calculations. The results of the study can provide theoretical references for the fusion operation of manned and unmanned aircraft.

Stochastic optimisation of district integrated energy systems based on a hybrid probability forecasting model

Day-ahead scheduling optimisation plays a significant role in solving stable operation problems of district integrated energy systems (DIESs) by carrying out scheduling optimisation of key equipment of the system based on forecasting data. However, the stable operation of DIESs is affected by multiple uncertainties from source-load. Day-ahead scheduling optimisation method is designed in this study for DIESs based on “prediction-optimisation” to reduce the impact of source-load uncertainty on the stable operation of system. Considering multidimensional source-load data, hybrid probability forecasting model based on Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN)-Long Short-Term Memory (LSTM)-Gaussian Process Quantile Regression (GPQR) is introduced to quantify the uncertainty using prediction interval. K-means method is used to generate typical scenarios in optimisation step and these scenarios are fed into stochastic optimisation to obtain day-ahead scheduling optimisation results. The experimental results in case study show that hybrid probability prediction model exhibits good prediction performance, while the day-ahead scheduling optimisation based on stochastic optimisation for system's key equipment has the smallest error in typical summer and winter days compared with the real situation, which is 0.018 and 0.0176, respectively. The “prediction-optimisation” approach proposed in this paper shows significant advantages for improving the performance of day-ahead scheduling optimisation of DIESs.

Application of improved Wolf pack algorithm in planning and operation of multi-microgrid systems with electric vehicles

Abstract With the rapid growth of renewable energy sources and the widespread use of electric vehicles (EVs), the planning and operation problems of multiple microgrids (MMGs) have become more complex and diverse. This paper develop an MMG model with multiple renewable energy sources and small-scale EVs, aiming to maximize the use of renewable energy sources and realize the charging demand of EVs, and highlighting the potential role of EVs in MMGs. In addition, the paper underscores the indispensable role of measurement technology in microgrids and the impetus that microgrid development provides for advancements in measurement technology. To this end, this paper proposes an improved Wolf pack algorithm (IWPA) based on the standard Wolf Pack Algorithm (WPA) with a spiral search approach and chaotic updating of individuals to improve the global search capability of the algorithm and the complexity of solving the scheduling problem. Through simulation experiments on ten standard test functions and examples, it is verified that the IWPA algorithm improves the search accuracy by 2.8%–6.8% and 13.9%–18.3% in the worst and best cases, respectively, in comparison with other algorithms, and it also has a faster convergence speed. Meanwhile, this paper proposes a load interval pricing strategy for the shortcomings of time-of-use pricing strategy and traditional real-time pricing strategy, which is simulated under grid-connected operation, isolated grid operation, and multi-microgrid cooperative operation modes, and the simulation results of the arithmetic example show that this strategy can effectively reduce carbon emissions, and IWPA can effectively coordinate renewable energy, EVs, and other energy resources to achieve efficient energy management of MMGs and supply-demand balance.

Performance and environmental sustainability studies on a dual-fuel IC engine working with producer gas of variable calorific values from rural biomass.

Decentralized power generation using renewable gaseous biofuels faces challenges due to their inconsistent quality and availability. Mixing producer gas (PG) with diesel as a secondary fuel is a promising option, but the non-stable calorific value (CV) of PG from different biomasses poses a serious problem for the efficient operation of a dual-fuel engine. This study aims to examine how the CV of PG from various biomasses affects a 3.75-kW dual-fuel IC engine's performance. The experimental facility, which has a dual-fuel engine and a 115-kW thermal gasifier, tested the blends of diesel and PG from different biomasses. We chose biomass based on its availability and PG's CV of 3.4, 4.4, 5.2, and 6.3MJ/Nm3. For this range of CV, the efficiency, energy consumption, and fuel replacement of a dual-fuel engine vary between 20.9 and 26.6%, 17.3 and 13.5MJ/kWh, and 10.8 and 76.9%, respectively. Furthermore, the blend with the maximum CV of PG had a 69.64% lower specific diesel consumption and an 86% higher diesel replacement rate than the blend with the lowest CV of PG. In terms of emission characteristics, the comparison showed a 2.02-7.06% reduction in NOx and a 4.05-55.6% increase in hydrocarbons (HCs) for the tested conditions. The overall observations demonstrated that a significant enhancement in a dual-fuel engine's performance is possible with a higher CV of PG. However, the emissions trade-offs demand additional optimization studies, as well as case-based research, in order to integrate renewable energy and emission management in smaller-scale applications across more geographies.

Comparison of different optimization techniques applied to optimal operation of energy storage systems in standalone and grid-connected direct current microgrids

This study addresses the problem of optimal operation and functioning of lithium-ion batteries in direct current (DC) microgrids with photovoltaic generators, in both urban and rural settings, under an approach that considers three mathematical models as objective functions: reduction of operational costs, reduction of power losses associated with energy transport, and reduction of CO2 emissions produced by conventional generators. After defining the objective functions, six optimization algorithms are integrated as solution methodologies: Equilibrium Optimizer (EO), Salp Swarm Algorithm (SSA), Particle Swarm Optimization (PSO), Sine and Cosine Algorithm (SCA), Black Hole Optimizer (BHO), and the Generalized Normal Distribution Optimizer (GNDO) algorithm. These methodologies are used to determine the hourly power flow through successive approximations, thus evaluating each of the objective functions with the system’s constraints in order to achieve reductions of each objective function and thereby confirm the quality of the solutions applied to the problem under analysis. Where, for the urban case of Medellín, the optimization achieved minimum reductions of 0.163% in fixed costs, 1.436% in variable costs, 7.160% in power losses, and 0.165% in CO2 emissions. In the rural case of Capurganá, the results showed minimum reductions of 0.095% in energy costs and 10.938% in power losses. These numerical results confirm the effectiveness of the applied optimization algorithms in reducing operational costs, power losses, and emissions, thereby validating the quality of the solutions for the analyzed problem.

Method for the consideration of statistically distributed geometrical deviations in the design of cylindrical roller bearing arrangements

Rolling bearings are of great importance in all areas of mechanical engineering due to their precise and low-friction guidance of rotating components at low cost. The design of rolling bearing arrangements is usually based on approximately ideal geometries of bearings and adjacent parts on which the bearing seats are located. However, real components inevitably show statistically distributed deviations from their nominal shapes, which are limited by tolerances. Tight tolerances result in high manufacturing costs while on the other hand their expansion leads to an increase of occurring geometrical deviations which cause changes in the bearing-internal contact and load conditions and can thus impair the operating behavior of the bearing, e.g. with regard to fatigue life, frictional torque or vibration behavior. By taking these effects into account in the design stage, potential problems in operation can be identified early during development and countermeasures can be taken, e.g. by adjusting bearing and seat tolerances. This enables an improvement of overall product quality and a reduction of costs. This paper presents a method for the integration of component deviations in the computation of the fatigue life (Lnmr) and dynamic behavior of cylindrical roller bearing arrangements—both of which are crucial design criteria—based on a combination of statistical tolerance analysis and multi-body simulations. The method is applied to an exemplary use case for illustration.

Features of railway transport operation in modern conditions

The application of the system of operational indicators, which developed during the years of the planned economy, in modern conditions requires an assessment for the changed working conditions of railway transport. However, it should be noted that any changes in the management of rail transport will have an impact on all logistics chains with the inclusion of rail transport. The emergence of wagon fleet operators and the transfer of almost all wagons of the network to them obviously reflected an increase in empty mileage, loss of versatility of the wagon fleet, an increase in the surplus of wagons on the infrastructure and, as a result, the risk of an increase in the number of ‟abandoned” trains. The analysis of the problems of the surplus of the wagon fleet and the increase in the number of ‟abandoned” trains makes it possible to structure the causes and differentiate the areas of management decisions for their leveling by JSC ‟Russian Railways”, operators of the wagon fleet and large cargo owners. The application of restrictions by JSC ‟Russian Railways” to the withdrawal of wagons on public tracks with obvious advantages in the context of the increasing strategic importance of railway transport may lead to the opposite effect of increasing the turnover of the wagon and the growth of the wagon fleet. The possibility of independent management of the wagon fleet for the largest operators with an analysis of the system of operational indicators with its subsequent improvement would allow solving a number of problems of rolling stock operation.

Design and Analysis of Load Frequency Control for a Two-Area Power System Using Conventional PID and FPID Controllers

Power system stability is required to maintain a continuous balance between power generation and load demand. Frequency control is also a major function of automatic generation control and one of the most important control problems in power system design and operation. So, a robust control system must be implemented for controlling the actual power and frequency. This paper mainly focuses on the design of a two-area power system with a rated frequency of 50 Hz, which is used in Myanmar, using the fuzzy-PID method to control the load frequency. It also aims to imply from one area to another when demand suddenly increases or decreases. It involves applying mathematical formulas and models to analyze how an automatic generation control works. The plan is first implemented in a single area before being modified to a two-area power system with and without controllers. The output results are simulated with MATLAB/ SIMULINK.