Statistical modeling and optimal energy distribution of cogeneration units by genetic algorithms

Our main objective is to evaluate the performance of a new method to optimize the energy management of a production system composed of six cogeneration units using artificial intelligence. The optimization criterion is economic and environmental in order to minimize the total fuel cost, as well as the reduction of polluting gas emissions such as COx, NOx and SOx. First, a statistical model has been developed to determine the power that the cogeneration units can provide. Then, an economic model of operation was developed: fuel consumption and pollutant gas emissions as a function of the power produced. Finally, we studied the energy optimization of the system using genetic algorithms (GA), and contribute to the research on improving the efficiency of the studied power system. The GA has a better optimization performance, it can easily choose satisfactory solutions according to the optimization objectives, and compensate for these defects using its own characteristics. These characteristics make GA have outstanding advantages in iterative optimization. The robustness of the proposed algorithm is validated by testing six cogeneration units, and the obtained simulation results of the proposed system prove the value and effectiveness of GA for efficiency improvement as well as operating cost minimization.

Research on Optimal Investment Reinsurance of Insurance Companies under Delayed Risk Model

The reinsurance and investment portfolio of insurance companies has always been a hot issue in insurance business. In insurance practice, it is inevitable for insurance companies to invest their own funds in order to expand their capital scale and enhance market competitiveness so as to obtain greater returns. At the same time, in order for insurance companies to disperse insurance risks and to avoid too concentrated claims or catastrophes caused by failure to perform compensation responsibilities, the purchase of reinsurance business has also become an important way. Stochastic control theory is widely used in reinsurance and investment issues. Based on the reinsurance system architecture, this paper establishes a reinsurance delay risk investment model, which reduces the amount of claims to be borne by buying proportional reinsurance to avoid bankruptcy caused by the excessive amount of claims. By using the delayed venture capital model to describe the earnings of insurance companies, the optimal investment and reinsurance strategy are solved under the optimization criterion of minimizing the probability of bankruptcy. By analyzing the model parameter data, the influence of each parameter on optimal investment strategy and optimal reinsurance strategy is discussed.

OPTIMIZATION OF PARAMETERS OF THE MOBILE MACHINE ADAPTIVE HYDRAULIC CIRCUIT

Mobile machine hydraulic circuits tend to adopt electrohydraulics. Such hydraulic circuits are based on controlled pumps, modulated hydraulics, sensors and controllers. This allows adapting the hydraulic circuit operating modes to the changes of external conditions of the machine operation. Application of hydraulic circuits with electrohydraulics in mobile machines allows to use mobile machines efficiently with a high number of removable endangers, increases their performance and improves the quality of performed works. The authors propose an adaptive hydraulic circuit for a mobile machine. The operation process in the adaptive hydraulic circuit in static and dynamic modes is determined by the interaction of the pump controller and pressure differential control valves. The hydraulic system operation stability, its fast response and readjustment are determined by the controller parameters. It has been revealed that the main parameters affecting the dynamic characteristics of the hydraulic system are: throttle area and coefficient of amplifying the pump controller orifice, dampener area and coefficient of amplifying the pressure differential control valve orifice. These parameters affect the stability, controlling and readjustment time in the hydraulic circuit differently. A functional including the values of controlling time , σ controlling and losses in the pump controller was used as an optimization criterion. The optimization has been made according to the developed mathematical model applying the method developed by I. Sobol and R. Statnikov. During the optimization each controller parameter changed on 3 levels. 81 tests were made and the best combination of controller parameters for the optimization criterion was determined. The following hydraulic circuit operation values were reached under the optimal values of parameters = 1.0·10-6 m2, = 1.0·10-3 m, = 1.2·10-6 m2, = 10·10-3 m: = 1.1 с, σ = 32 %, = 0.82 kW that comply with the requirements towards hydraulic circuits of mobile machines.

Collaborative Workplace Design: A Knowledge-Based Approach to Promote Human–Robot Collaboration and Multi-Objective Layout Optimization

The innovation-driven Industry 5.0 leads us to consider humanity in a prominent position as the center of the manufacturing field even more than Industry 4.0. This pushes us towards the hybridization of manufacturing plants promoting a full collaboration between humans and robots. However, there are currently very few workplaces where effective Human–Robot Collaboration takes place. Layout designing plays a key role in assuring safe and efficient Human–Robot Collaboration. The layout design, especially in the context of collaborative robotics, is a complex problem to face, since it is related to safety, ergonomics, and productivity aspects. In the current work, a Knowledge-Based Approach (KBA) is adopted to face the complexity of the layout design problem. The framework resulting from the KBA allows for developing a modeling paradigm that enables us to define a streamlined approach for the layout design. The proposed approach allows for placing resource within the workplace according to a defined optimization criterion, and also ensures compliance with various standards. This approach is applied to an industrial case study in order to prove its feasibility. A what-if analysis is performed by applying the proposed approach. Changing three control factors (i.e., minimum distance, robot speed, logistic space configuration) on three levels, in a Design of Experiments, 27 layout configurations of the same workplace are generated. Consequently, the inputs that most affect the layout design are identified by means of an Analysis of Variance (ANOVA). The results show that only one layout is eligible to be the best configuration, and only two out of three control factors are very significant for the designing of the HRC workplace layout. Hence, the proposed approach enables the designing of standard compliant and optimized HRC workplace layouts. Therefore, several alternatives of the layout for the same workplace can be easily generated and investigated in a systematic manner.

INCREASING MICROGRID ENERGY EFFICIENCY WITH DIESEL GENERATORS

It is shown that increasing the energy efficiency of Microgrid with diesel generators requires solving the problem of optimizing the modes of operation of Microgrid using as an optimization criterion for reducing the consumption of primary fuel diesel generators. To study the energy efficiency of such types of Microgrid as a criterion that has a direct impact on the amount of electricity generated, selected adequate accounting of primary fuel consumption when generating a given amount of electricity in the system. The article determines that one of the important indicators of diesel generator sets is their efficiency, which is determined by the ratio of energy produced to fuel consumption per hour of operation at rated load. It is shown that the reduction of fuel consumption allows to increase the efficiency of diesel generators, and different types of steady and transient modes of diesel generators significantly affect the efficiency of Microgrid in terms of technical and financial efficiency. To improve the technical and economic indicators in Microgrid with diesel generators, the article proposes to use the electric cost model of the power generation system, which allows to calculate both the dynamic change of generated power and the dynamic change of its cost and the cost of primary fuel. This model allows flexible nonlinear tracking of fuel consumption, which, taking into account the cost of diesel fuel, can serve as an economic criterion for determining the energy efficiency of the generating system. The article presents an algorithm for evaluating the financial and technical performance of Microgrid in dynamic modes over a period of technology, which not only evaluates the economic and energy efficiency of Microgrid with diesel generators, but can also be used to modify Smart meters, which can significantly expand their functionality.

Optimal spatial allocation of enzymes as an investment problem

Given a limited number of molecular components, cells face various allocation problems demanding decisions on how to distribute their resources. For instance, cells decide which enzymes to produce at what quantity, but also where to position them. Here we focus on the spatial allocation problem of how to distribute enzymes such as to maximize the total reaction flux produced by them in a system with given geometry and boundary conditions. So far, such distributions have been studied by computational optimization, but a deeper theoretical understanding was lacking. We derive an optimal allocation principle, which demands that the available enzymes are distributed such that the marginal flux returns at each occupied position are equal. This ‘homogeneous marginal returns criterion’ (HMR criterion) corresponds to a portfolio optimization criterion in a scenario where each investment globally feeds back onto all payoffs. The HMR criterion allows us to analytically understand and characterize a localization-delocalization transition in the optimal enzyme distribution that was previously observed numerically. In particular, our analysis reveals the generality of the transition, and produces a practical test for the optimality of enzyme localization by comparing the reaction flux to the influx of substrate. Based on these results, we devise an additive construction algorithm, which builds up optimal enzyme arrangements systematically rather than by trial and error. Taken together, our results reveal a common principle in allocation problems from biology and economics, which can also serve as a design principle for synthetic biomolecular systems.

An Improved Structural Analysis Method for Isolator with Quasi-Zero-Stiffness Characteristic

A typical quasi-zero-stiffness (QZS) vibration isolator consisting of a vertical spring and two oblique springs has been widely researched on its static and dynamic characteristics. A general criterion for determining structural parameters of QZS isolator is to achieve low nondimensional stiffness around the equilibrium position. However, lower nondimensional stiffness of linear isolator means lower isolation frequency, which may be invalid on QZS isolator. Because there is an implicit relationship between geometric parameter and stiffness ratio of QZS isolator, this study presents an improved optimization criterion for determining the optimal structural parameters of the typical QZS isolator. The optimization criterion is that the QZS isolator has the maximum displacement range around the equilibrium position without exceeding given natural frequency, rather than given nondimensional stiffness. The results show that isolator with these optimal parameters can achieve lower stiffness around the equilibrium position and better vibration isolation performance. Furthermore, an extended QZS isolator consisting of vertical spring with fixed stiffness and prestressed oblique springs is discussed to further improve stiffness characteristic. Better stiffness performance can be obtained when the prestressed oblique springs have softening stiffness and the exponent of the nonlinear stiffness is 2. Considering the existence of friction in practical application, the influence of friction on both static and dynamic characteristics is investigated. The analysis reveals that friction has little influence on its stiffness characteristic around the static equilibrium position and friction damping produced by friction affects the response amplitude and resonant frequency in dynamics.

Improvement in Ridge Coefficient Optimization Criterion for Ridge Estimation-Based Dynamic System Response Curve Method in Flood Forecasting

The ridge estimation-based dynamic system response curve (DSRC-R) method, which is an improvement of the dynamic system response curve (DSRC) method via the ridge estimation method, has illustrated its good robustness. However, the optimization criterion for the ridge coefficient in the DSRC-R method still needs further study. In view of this, a new optimization criterion called the balance and random degree criterion considering the sum of squares of flow errors (BSR) is proposed in this paper according to the properties of model-simulated residuals. In this criterion, two indexes, namely, the random degree of simulated residuals and the balance degree of simulated residuals, are introduced to describe the independence and the zero mean property of simulated residuals, respectively. Therefore, the BSR criterion is constructed by combining the sum of squares of flow errors with the two indexes. The BSR criterion, L-curve criterion and the minimum sum of squares of flow errors (MSSFE) criterion are tested on both synthetic cases and real-data cases. The results show that the BSR criterion is better than the L-curve criterion in minimizing the sum of squares of flow residuals and increasing the ridge coefficient optimization speed. Moreover, the BSR criterion has an advantage over the MSSFE criterion in making the estimated rainfall error more stable.

Modeling of Curvilinear Steel Rod Structures Based on Minimal Surfaces

The article deals with shaping effective curvilinear steel rod roof structures using genetic algorithms by implementing them for the analysis of various case studies in order to find new and efficient structures with positive characteristics. The structures considered in this article are created on the basis of the Enneper surface and minimal surfaces stretched on four arcs. On the Enneper surface, a single layer grid is used, while on the other surfaces, two-layer ones. The Enneper form structure with four supports and the division into an even number of parts along the perimeter of the covered place proved to be the most efficient, and the research showed that small modifications of the initial base surface in order to adapt the structure to the roof function did not significantly affect its effectiveness. However, the analysis and comparison of single and double-shell rod structures based on minimal surfaces stretched on four arcs have shown that a single-shell structure is much more effective than a double one. The paper considers the theoretical aspects of shaping effective structures, taking their masses as the optimization criterion. The optimization helped to choose the best solutions due to structures’ shapes and topologies. However, the obtained, optimized results can find practical applications after conducting physical tests.

OPTIMIZATION OF THE DRYING PROCESS GRAIN CROP IN A TUMBLE DRYER WITH HEAT PUMP

Рассмотрена возможность автоматической оптимизации процесса сушки зернобобовых культур в барабанной сушилке с парокомпрессионным тепловым насосом по технико-экономическому показателю при выполнении ограничений на качество готового продукта. В качестве критерия оптимизации использованы суммарные энергетические затраты, приходящиеся на единицу массы испаряемой влаги. Определены три составляющие числителя критерия оптимизации: затраты на преодоление аэродинамического сопротивления слоя продукта в барабанной сушилке, затраты электроэнергии на привод компрессора парокомпрессионного теплового насоса (ТНУ), привод вращения барабана. Затраты электроэнергии на привод компрессора рассчитывали через холодопроизводительность ТНУ. Установлена зависимость разности влагосодержаний сушильного агента до сушки и после нее от степени заполнения сушильного барабана зернистым продуктом при различных значениях его начальной влажности. Получена однозначная функциональная связь суммарных энергетических затрат, приходящихся на единицу массы испаряемой влаги от степени заполнения барабана. На примере сушки зерна пшеницы в барабанной сушилке с профильной канальной насадкой, укомплектованной парокомпрессионным тепловым насосом, показана возможность управления степенью заполнения барабана по минимальной величине удельных энергетических затрат. Сочетанием экспериментальных и аналитических методов исследования разработана система экстремального управления процессом сушки зерна в барабанной сушилке с тепловым насосом, позволяющая с помощью микропроцессора осуществлять оперативный поиск оптимального значения степени заполнения барабана, что существенно снизит удельные энергозатраты на процесс сушки. При этом по текущей информации, получаемой с датчиков, микропроцессор непрерывно вырабатывает сигнал отклонения текущего значения степени заполнения от оптимального и посредством исполнительного механизма воздействует на расход влажного зерна, а следовательно, и на степень заполнения барабана продуктом, так чтобы суммарная удельная мощность энергооборудования для выбранного режима сушки была бы минимальной. Для многозонной барабанной сушилки предложенный алгоритм управления необходимо повторять для каждой из зон, в которых степень заполнения регулируется с помощью секторных заслонок. The possibility of automatic optimization of the drying process of legumes in a tumble dryer with a steam compression heat pump according to the technical and economic indicator when the quality of the finished product is limited. As an optimization criterion, the total energy costs per unit mass of evaporated moisture. Three components of the numerator of the optimization criterion are determined: the costs of overcoming the aerodynamic resistance of the product layer in the drum dryer, power consumption for the compressor drive of a steam compression heat pump (HPI), drum rotation drive. The energy costs for the compressor drive were calculated through the cooling capacity of the HPI. The dependence the difference in the moisture content of the drying agent before and after drying on the degree of filling the drying drum with a granular product is established for different values its initial humidity. An unambiguous functional relationship between the total energy costs per unit mass of evaporated moisture, the degree filling the drum. On the example wheat grain drying in a drum drier with a profile channel nozzle equipped with a steam compression heat pump, it is shown that it is possible to control the degree of filling of the drum by the minimum value of the specific energy costs. A combination experimental and analytical research methods developed a system for extreme control of the drying process grain in a drum dryer with a heat pump, allowing using the microprocessor to perform an operative search for the optimal degree of filling of the drum, which will significantly reduce the specific energy consumption for the drying process. At the same time, according to the current information received from the sensors, the microprocessor continuously generates a signal of deviation of the current value the filling degree from the optimal one and by means of the actuator it affects the consumption wet grain, and consequently, the degree of filling of the drum with the product, so that the total specific power of the power equipment for the selected drying regime would be minimal. For a multi-zone drum dryer, the proposed control algorithm must be repeated for each zone in which the degree of filling is controlled by sectoral dampers.