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1
Gorev, V. A. "Model load in case of an internal explosion." Pozharovzryvobezopasnost/Fire and Explosion Safety 30, no. 3 (July 12, 2021): 5–15. http://dx.doi.org/10.22227/0869-7493.2021.30.03.5-15.
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Introduction. Presently, there are no model loads that describe the burst effect of an internal explosion. The goal of the article is to design a model load that characterizes an internal explosion with regard for the effect of inertial safety structures. The author provides relevant examples.Methods. The experiment and the numerical modeling identify the characteristics of an internal explosion, primarily, its destructive effect. First of all, these characteristics include the pressure value and rate in the process of the first peak formation. A drop follows the first peak. Another rise to the second peak is followed by the final pressure drop. The rise to the first peak is described by a cubic parabola. The constant value of pressure is equal to the highest value of the two peaks. It replaces the drop and rise between the peaks. The linear dependence describes the area of the final pressure drop, so that the deformation is completed at the end point. The time of the pressure rise is determined by breakup, and it takes account of the characteristics of safety structures. The time of the second peak is the time when the flame area is maximal.Results and discussion. The deformation that may occur before the first peak represents a solution to the equation, describing the beam motion. This equation is provided in the article. The deformation between the peaks is determined by the balance of energy. The deformation, that occurs when the pressure drops, is identified by the solution to the motion equation. The solution is subject to the deformation completion condition.Conclusions. The results show that the time between the peaks is important when the pressure is close to maximal. The analysis identifies the conditions under which deformation remains elastic. These results can be contributed to the assessment of the bearing capacity of buildings that accommodate explosive production facilities. This approach ensures conservative results.
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Kumar, Sanjeet, Deepak Kumar, Jayant Jain, and Jaswant Kumar Hirwani. "Influence of load, sliding speed, and microstructure on wear response of AZ91 Mg alloy." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 230, no. 12 (August 5, 2016): 1462–69. http://dx.doi.org/10.1177/1350650116638601.
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This article deals with the tribological study of solution-treated and peak aged AZ91 Mg alloy. Tribological studies were carried out using reciprocating sliding contact under lubricated conditions. The effect of load, sliding speed, and microstructure on wear response of AZ91 Mg alloy was investigated. The wear response was characterized using optical microscopy, scanning electron microscope, and energy dispersive X-ray spectroscopy mapping. The peak aged alloy showed excellent wear resistance against Al6351 Al alloy as compared with solution-treated alloy. The formation of γ-Mg17Al12 precipitates in aged sample was found to increase the wear resistance. The specific wear rate for peak aged alloy was almost one-third than that of solution-treated alloy. In both the samples, i.e. solution-treated and peak aged, the coefficient of friction decreases with increase in sliding speed at low load, while the behavior of peak aged sample was found to be opposite at higher load. At low load, the wear mode for peak aged sample was oxidative which further shifted to adhesive at higher loads.
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Liu, Chun Yang, Bing Xin Li, Jin San Ju, Xiu Gen Jiang, and Xiao Chuan You. "Numerical Solution of Elas-Plastic Impact Load of Tube Column." Advanced Materials Research 33-37 (March 2008): 363–68. http://dx.doi.org/10.4028/www.scientific.net/amr.33-37.363.
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The explicit numerical method is used to trace the impact procedure of the tube columns impacted by a rigid body. The bar and rectangle tube models are both used to simulate the tube column. The elastic and elas-plastic impact load with different mass ratio and impact speed are obtained. The calculation results show that: for elastic models, the bigger the mass ratio and the higher the rigid body speed, the bigger the peak value of elastic impact load; at the same time, the more obvious the reduction effect of local buckling of rectangle tube on the peak value of impact load and the longer the contact time of tube model; so the peak value of impact load of the rectangle tube is not proportional to the rigid body speed. The stress wave in the tube causes a little difference between the load curves of tube model and bar model. For elas-plastic models, the higher the rigid body speed and the smaller the mass ratio, the bigger the peak value of impact load and the longer the contact time. The higher the rigid body speed, the bigger the difference between elastic and elas-plastic impact load peak value due to the expanding of plasticity. Because of the effect of local buckling, the peak value of elas-plastic impact load of rectangle tube is always lower than that of bar.
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Popov, I. P. "Peak Load Balancing for Engineering Vehicles." Herald of the Bauman Moscow State Technical University. Series Mechanical Engineering, no. 3 (132) (June 2020): 85–93. http://dx.doi.org/10.18698/0236-3941-2020-3-85-93.
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The paper considers the possibility of equipping engineering vehicles with inertial capacitance energy storage units, which should allow the power plant loads to be evened out, in turn leading to reducing the output power, mass and dimensions of the plant. In a range of engineering vehicles, such as excavators, bulldozers, diesel shunter locomotives and so on, loads are of a substantially irregular character. Peak loads are what determines the output power of power plants. It is evident that the power plant is not fully loaded most of the time. We propose a technological solution for balancing peak loads in engineering vehicles. Since operation modes of engineering vehicles change relatively frequently, it is efficient and advisable to equip them with energy storage units. The storage unit will not only level the power plant load, but also allow the energy to be recuperated during deceleration, which should improve the energy efficiency of the machine. We present the theoretical background required to develop an inertial capacitance energy storage unit, which is implemented as a direct current machine featuring a super flywheel. Employing flywheels in engineering vehicles is feasible due to their total mass requirements being flexible. Another advantage of certain engineering vehicles is their electro-mechanical transmission, the presence of which should minimise the development effort concerning the inertial capacitance energy storage unit discussed in the paper engineering vehicle, energy storage unit, super flywheel, power plant, energy efficiency
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Huang, Zhiyuan, Ruihua Xu, Wei Fan, Feng Zhou, and Wei Liu. "Service-Oriented Load Balancing Approach to Alleviating Peak-Hour Congestion in a Metro Network Based on Multi-Path Accessibility." Sustainability 11, no. 5 (March 1, 2019): 1293. http://dx.doi.org/10.3390/su11051293.
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To further improve the service quality and reduce safety risks in current congested metro systems during peak hours, this paper presents a load balancing (LB) approach so that available capacity can be utilized more effectively in order to alleviate peak hour congestion. A set of under-utilized yet effective alternative routes were searched using a deletion algorithm (DA) in order to share the passenger loads on overcrowded metro line segments. An optimization model was constructed based on an improved route generalized time utility function considering the penalties of both in-vehicle congestion and transfers. A detailed load balancing solution was generated based on the proposed algorithm. A real-world example of three overloaded metro line segments in the Shanghai metro network were selected and used to verify the feasibility and validity of the developed load balancing method. The results show that the load balancing method can effectively reduce the overcrowding situation to a great extent. Finally, two prospective inducing schemes are discussed to help implement the load balancing solution in the actual metro system in an efficient and effective manner.
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Baranovsky, Vladimir, and Maxim Lipatov. "Marine steam-gas semi-closed cycle power plant for peak loads." Energy Safety and Energy Economy 2 (April 2021): 21–25. http://dx.doi.org/10.18635/2071-2219-2021-2-21-25.
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A wide range of efficient gas turbine engines has been developed at UEC NPO Saturn, Russia. Those engines can be successfully used for developing a marine steam-gas semi-closed cycle power plant to compensate peak loads on ships and vessels. This compact steam-gas power plant will demonstrate high efficiency which doesn’t change significantly depending on the load when compared to conventional steam-gas power plants. Also, this solution can possibly change the diesel engine prevalence among marine power plants.
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Kumar, D. Sai. "Demand Side Management Techniques for Peak Reduction." International Journal for Research in Applied Science and Engineering Technology 9, no. VII (July 30, 2021): 2911–13. http://dx.doi.org/10.22214/ijraset.2021.36979.
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Industrial growth is the back bone for the development of any nation. Industries are mainly dependent on electrical energy. But from the various studies, the sources for electrical energy are decreasing gradually, and in turn, the gap is increasing between the supplier and the load. The solution for this scenario is optimal utilization of resources. To overcome this problem , the concept Demand Side Management (DSM) has emerged in Power System Planning and Management. The principle objective of DSM is mutual understanding between the supplier and the consumer for maximizing benefits and minimizing inconvenience. The aim of this research work is selection and application of appropriate DSM techniques to industrial and domestic loads for peak load management and energy conservation, that is to control the maximum demand during the peak hours and saving the energy by using the energy efficient and intelligent appliances like air conditioners and water heaters. DSM includes techniques like the End Use Equipment Control, the Load Priority Technique, he Peak Clipping & Valley filling, the Differential Tariff and Resizing of the equipment. Depending upon the application, all the techniques may be applied sequentially, or only a few of them can be applied. There is a lot of ambiguity in the selection of DSM techniques, because the application of each DSM technique depends on the case study and the problem associated with the respective case study. After comprehensive understanding of a particular case, a thorough investigation and subsequent data analysis pave the way for the selection of appropriate DSM technique/techniques
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Chen, Zhi Wei, and Jian Gang Wu. "Study on Generalized Fatigue Damage under Random Loading." Key Engineering Materials 324-325 (November 2006): 1161–64. http://dx.doi.org/10.4028/www.scientific.net/kem.324-325.1161.
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Generalized fatigue damage is derived based on S-N curve under constant amplitude loads with S characterizes the load cycle by the combination of load peak and load amplitude. For random fatigue loads, a natural choice is to use half cycle (Range) counting method. Rain Flow counting is popular due to its useful nature to pick-out full cycles among random loads. It is found in the present research through analysis and verified by experimental results that Rain Flow counting seriously overestimate the damage for the actual true random loads owing to its inherent nature and the Range counting method is more reliable. As the filtering threshold increases gradually, the overestimation effect by Rain Flow counting method becomes less, and the calculated damages by Rain Flow and Range counting begin to converge. The filtering threshold damage corresponding to the “fatigue limits” for the concerned case was calculated. According to equal damage principle, the filtering threshold amplitudes were derived and found to vary with the load peaks. In practice, an acceptable solution is to use quasi-variable filtering thresholds.
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Kim, Hyung-Joon, and Mun-Kyeom Kim. "Multi-Objective Based Optimal Energy Management of Grid-Connected Microgrid Considering Advanced Demand Response." Energies 12, no. 21 (October 30, 2019): 4142. http://dx.doi.org/10.3390/en12214142.
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This paper proposes an optimal energy management approach for a grid-connected microgrid (MG) by considering the demand response (DR). The multi-objective optimization framework involves minimizing the operating cost and maximizing the utility benefit. The proposed approach combines confidence-based velocity-controlled particle swarm optimization (CVCPSO) (i.e., PSO with an added confidence term and modified inertia weight and acceleration parameters), with a fuzzy-clustering technique to find the best compromise operating solution for the MG operator. Furthermore, a confidence-based incentive DR (CBIDR) strategy was adopted, which pays different incentives in different periods to attract more DR participants during the peak period and thus ensure the reliability of the MG under the peak load. In addition, the peak load shaving factor (PLSF) was employed to show that the reliability of the peak load had improved. The applicability and effectiveness of the proposed approach were verified by conducting simulations at two different scales of MG test systems. The results confirm that the proposed approach not only enhances the MG system peak load reliability, but also facilitates economical operation with better performance in terms of solution quality and diversity.
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Conteh, Abdul, Mohammed Elsayed Lotfy, Oludamilare Bode Adewuyi, Paras Mandal, Hiroshi Takahashi, and Tomonobu Senjyu. "Demand Response Economic Assessment with the Integration of Renewable Energy for Developing Electricity Markets." Sustainability 12, no. 7 (March 27, 2020): 2653. http://dx.doi.org/10.3390/su12072653.
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Electricity disparity in sub-Saharan Africa is a multi-dimensional challenge that has significant implications on the current socio-economic predicament of the region. Strategic implementation of demand response (DR) programs and renewable energy (RE) integration can provide efficient solutions with several benefits such as peak load reduction, grid congestion mitigation, load profile modification, and greenhouse gas emissions reduction. In this research, an incentive and price-based DR programs model using the price elasticity concepts is proposed. Economic analysis of the customer benefit, utility revenue, load factor, and load profile modification are optimally carried out using Freetown (Sierra Leone) peak load demand. The strategic selection index is employed to prioritize relevant DR programs that are techno-economically beneficial for the independent power producers (IPPs) and participating customers. Moreover, optimally designed hybridized grid-connected RE was incorporated using the Genetic Algorithm (GA) to meet the deficit after DR implementation. GA is used to get the optimal solution in terms of the required PV area and the number of BESS to match the net load demand after implementing the DR schemes. The results show credible enhancement in the load profile in terms of peak period reduction as measured using the effective load factor. Moreover, customer benefit and utility revenues are significantly improved using the proposed approach. Furthermore, the inclusion of the hybrid RE supply proves to be an efficient approach to meet the load demand during low peak and valley periods and can also mitigate greenhouse gas emissions.
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Al-Nama, M. A., M. S. Al-Hafid, and A. S. Al-Fahadi. "Estimation of the Consumer Peak Load for the Iraqi Distr ibution System Using intelligent Methods." Iraqi Journal for Electrical and Electronic Engineering 7, no. 2 (December 1, 2011): 180–84. http://dx.doi.org/10.37917/ijeee.7.2.15.
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The drastic increase of residential load consumption in recent years result in over loading feeder lines and transformers for the Iraqi northern area distribution system especially in the city of Mosul. Solution for this problem require up to date research consumers load study to find the proper solution to stop excess overload in the transformers and the feeders. This paper include the regional survey for samples of consumers representing typical types of different standard of living and energy consumption by distributing questioners contain list of information such as load type in daily use. Also current readings are recorded for the individual consumer for the months of the year 2006. In addition to those readings, energy consumption is recorded once every two months. The registered readings are used in conjunction with the list of questionnaires to find a sample (for different loads) that coincide with the list of questionnaires for current and energy readings. Resulting in the feasibility of using the sample to know the peak value of current for any consumer even if he is not included in the list of questionnaires and for any new consumer, since it become possible to decide the size of the transformers and feeder lines, to overcome the problem of overloading in any part of the distribution system. The Artificial Neural Network (ANN) is used in this paper to find the above mentioned sample.
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El-Saadawy, Magdi, Mohamed Adel El-Sayes, and M. El-Maghraby. "New Solution Algorithm for Peak Shaving and Load Leveling Using Photovoltaic/Battery Aggregation.(Dept.E)." MEJ. Mansoura Engineering Journal 13, no. 1 (May 26, 2021): 1–26. http://dx.doi.org/10.21608/bfemu.2021.172527.
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Sadiq, Sadiq E., Muhsin J. Jweeg, and Sadeq H. Bakhy. "Strength Analysis of an Aircraft Sandwich Structure with a Honeycomb Core: Theoretical and Experimental Approaches." Engineering and Technology Journal 39, no. 1A (January 25, 2021): 153–66. http://dx.doi.org/10.30684/etj.v39i1a.1722.
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In this paper, the strength of aircraft sandwich structure with honeycomb core under bending load was evaluated theoretically and experimentally based on failure mode maps. A failure mode map for the loading under three-point bending was constructed theoretically to specify the failure modes and corresponding load. Three point bending test for aluminum honeycomb sandwich beam has been achieved to measure the peak load and maximum deflection. The obtained results elucidated a good agreement between the theoretical solutions and experimental tests, where the error ratio was not exceeded 12%. The core height, the cell size and the cell wall thickness were selected to explore the effect of honeycomb parameters on the strength of sandwich structure. In order to obtain the optimum solution of peak load and maximum deflection and energy absorption, Response Surface Methodology (RSM) was used. Results showed that the maximum bending load, minimum deflection, and maximum energy absorption were found at 25 mm core height, 10 mm size cell and 1 mm cell wall thickness. The optimal value of maximum bending load, minimum deflection and maximum energy absorption were 1975.3415 N, 1.0402 mm and 1.0229 J respectively.
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Taiwo, Ogunboyo Patrick, and Melodi O. Adegoke. "Electrical Distribution Industry - Long Term Load Forecast on Ilesha Road 11kV Feeder, Akure, Ondo State, Nigeria." International Journal of Engineering Research in Africa 37 (August 2018): 52–61. http://dx.doi.org/10.4028/www.scientific.net/jera.37.52.
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This paper presents an investigative study on a selected 11 kV distribution feeder network in Akure township, Nigeria, aimed at evaluating power distribution problems and solution proposals for effective application of existing 11 kV feeders for power supply within Nigeria. Based on peak loads recorded on the feeder for 8 years a long term load forecast up to 2021 was carried out using “Trend’ and “Growth’ functions in Excel worksheet. These functions use Method of Least Squares. The peak network load is 8 MW and the expected load in 2021 is 14.5 MW (18.5 MVA at 0.8 power factor) after an exponential growth rate of 0.6 MW per annum. There is need to increase the rating of the power transformer feeding the feeder in order to enhance the security power supply to the network. Furthermore, the Power Company must provide standard input voltage (1.05x11 kV) to the network in order to normalize end-users voltage quality.
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Chen, Ke, and Xue Feng Tong. "Numerical Solution of Dynamic Responses of Moving Load on Ice Sheet." Applied Mechanics and Materials 138-139 (November 2011): 44–49. http://dx.doi.org/10.4028/www.scientific.net/amm.138-139.44.
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To study on the breaking mechanism of an ice sheet under moving load, have need for researching the displacement responses of ice sheet. From viscoelastic vibration differential equation of ice sheet, dynamic equation of ice sheet was established under moving load in the cylindrical coordinate system, and the boundary conditions were given for solving differential equations. Used Hankel transform and Laplace transform to solve Green function of ice sheet vibration responses under loading, and derived the displacement response of ice sheet on the base of Green function. The example calculation shows that the displacement responses of ice sheet of 0.5m thickness is got under moving load at different time, the peak position of gravity wave propagation lags behind the loading point.
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Muhsen, Dhiaa Halboot, Haider Tarish Haider, Yaarob Al-Nidawi, and Tamer Khatib. "Optimal Home Energy Demand Management Based Multi-Criteria Decision Making Methods." Electronics 8, no. 5 (May 10, 2019): 524. http://dx.doi.org/10.3390/electronics8050524.
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From the growth of residential energy demands has emerged new approaches for load scheduling to realize better energy consumption by shifting the required demand in response to cost changes or incentive offers. In this paper, a hybrid method is proposed to optimize the load scheduling problem for cost and energy saving. The method comprises a multi-objective optimization differential evolution (MODE) algorithm to obtain a set of optimal solutions by minimizing the cost and peak of a load simultaneously, as a multi-objective function. Next, an integration of the analytic hierarchy process (AHP) and a technique for order preferences by similarity to ideal solution (TOPSIS) methods are used as multi-criteria decision making (MCDM) methods for sorting the optimal solutions’ set from the best to the worst, to enable the customer to choose the appropriate schedule time. The solutions are sorted based on the load peak and energy cost as multi-criteria. Data are for ten appliances of a household used for 24 h with a one-minute time slot. The results of the proposed method demonstrate both energy and cost savings of around 47% and 46%, respectively. Furthermore, the results are compared with other recent methods in the literature to show the superiority of the proposed method.
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Benysek, G., M. Jarnut, SZ Werminski, and J. Bojarski. "Distributed active demand response system for peak power reduction through load shifting." Bulletin of the Polish Academy of Sciences Technical Sciences 64, no. 4 (December 1, 2016): 925–36. http://dx.doi.org/10.1515/bpasts-2016-0101.
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Abstract The large variability in power consumption in electrical power systems (EPS) influences not only growth balance losses and technical losses, but also in some cases reduces energy security. Delayed restoration of power generation, combined with unpredictable weather events leading to the loss of generating power can lead to a situation in which to save the stability of the power system there must be introduced in the system a load power limit or even disconnection of end-user in a given area, which will significantly reduce the comfort of use of energy. This situation can be prevented through either the building of new intervention power units or the aggregated use of new energy technologies, such as distributed network resources (DER), which are part of an intelligent Smart Grid network. Such resources bring together virtual power plants (VPP) and demand side management (DSM). The article presents an alternative decentralized active demand response (DADR) system, that by acting on selected groups of loads reduces peak loads with minimized loss of comfort of energy in use for the end-user. The system operates without any communication. The effectiveness of the proposed solution has been confirmed, outlined in test results obtained by the authors from a developed analytical model, which also contains stochastic algorithms to decrease the negative impact of such DSM systems on the power system (power overshoot and oscillation).
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Acquah, Moses Amoasi, and Sekyung Han. "Online Building Load Management Control with Plugged-in Electric Vehicles Considering Uncertainties." Energies 12, no. 8 (April 15, 2019): 1436. http://dx.doi.org/10.3390/en12081436.
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Robust operation of load management control for a building is important to account for the uncertainty in demand as well as any distributed sources connected to the building. This paper discussed an online load management control solution using distributed energy storage (DES) while considering uncertainties in demand as well as DES to reduce peak demand for economic benefit. In recent years’ demand-side management (DSM) solutions using DES such as stationary energy management system (BESS) and plugged-in electric vehicles (PEV) have been popularised. Most of these solutions resort to deterministic load forecast for the day ahead energy scheduling and do not consider the uncertainties in demand and DES making these solutions vulnerable to uncertainties. This study presents an online density demand forecast, k-means clustering of PEV groups and stochastic optimisation for robust operation of BESS and PEV for a building. The proposed method accounts for uncertainties in demand and uncertainties due to mobile energy storage as presented by PEVs. For a case study, we used data obtained from an industrial site in South Korea. The verified results as compared to other methods with a deterministic approach prove the solution is efficient and robust.
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Naik, Ketaki Bhalchandra, G. Meera Gandhi, and S. H. Patil. "Pareto Based Virtual Machine Selection with Load Balancing in Cloud Data Centre." Cybernetics and Information Technologies 18, no. 3 (September 1, 2018): 23–36. http://dx.doi.org/10.2478/cait-2018-0036.
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Abstract Cloud Data centers have adopted virtualization techniques for effective and efficient compilation of an application. The requirements of application from the execution perspective are fulfilled by scaling up and down the Virtual Machines (VMs). The appropriate selection of VMs to handle the unpredictable peak workload without load imbalance is a critical challenge for a cloud data center. In this article, we propose Pareto based Greedy-Non dominated Sorting Genetic Algorithm-II (G-NSGA2) for agile selection of a virtual machine. Our strategy generates Pareto optimal solutions for fair distribution of cloud workloads among the set of virtual machines. True Pareto fronts generate approximate optimal trade off solution for multiple conflicting objectives rather than aggregating all objectives to obtain single trade off solution. The objectives of our study are to minimize the response time, operational cost and energy consumption of the virtual machine. The simulation results evaluate that our hybrid NSGA-II outperforms as compared to the standard NSGA-II Multiobjective optimization problem.
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Behrens, D., T. Schoormann, and R. Knackstedt. "Developing an Algorithm to Consider Mutliple Demand Response Objectives." Engineering, Technology & Applied Science Research 8, no. 1 (February 20, 2018): 2621–26. http://dx.doi.org/10.48084/etasr.1819.
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Due to technological improvement and changing environment, energy grids face various challenges, which, for example, deal with integrating new appliances such as electric vehicles and photovoltaic. Managing such grids has become increasingly important for research and practice, since, for example, grid reliability and cost benefits are endangered. Demand response (DR) is one possibility to contribute to this crucial task by shifting and managing energy loads in particular. Realizing DR thereby can address multiple objectives (such as cost savings, peak load reduction and flattening the load profile) to obtain various goals. However, current research lacks algorithms that address multiple DR objectives sufficiently. This paper aims to design a multi-objective DR optimization algorithm and to purpose a solution strategy. We therefore first investigate the research field and existing solutions, and then design an algorithm suitable for taking multiple objectives into account. The algorithm has a predictable runtime and guarantees termination.
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Martins, Rodrigo, Holger Hesse, Johanna Jungbauer, Thomas Vorbuchner, and Petr Musilek. "Optimal Component Sizing for Peak Shaving in Battery Energy Storage System for Industrial Applications." Energies 11, no. 8 (August 7, 2018): 2048. http://dx.doi.org/10.3390/en11082048.
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Recent attention to industrial peak shaving applications sparked an increased interest in battery energy storage. Batteries provide a fast and high power capability, making them an ideal solution for this task. This work proposes a general framework for sizing of battery energy storage system (BESS) in peak shaving applications. A cost-optimal sizing of the battery and power electronics is derived using linear programming based on local demand and billing scheme. A case study conducted with real-world industrial profiles shows the applicability of the approach as well as the return on investment dependence on the load profile. At the same time, the power flow optimization reveals the best storage operation patterns considering a trade-off between energy purchase, peak-power tariff, and battery aging. This underlines the need for a general mathematical optimization approach to efficiently tackle the challenge of peak shaving using an energy storage system. The case study also compares the applicability of yearly and monthly billing schemes, where the highest load of the year/month is the base for the price per kW. The results demonstrate that batteries in peak shaving applications can shorten the payback period when used for large industrial loads. They also show the impacts of peak shaving variation on the return of investment and battery aging of the system.
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Mourelatos, Z. P. "Gas Lubrication of a Ringless Piston in an Internal Combustion Engine Under Dynamic Loading." Journal of Tribology 110, no. 4 (October 1, 1988): 718–26. http://dx.doi.org/10.1115/1.3261719.
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A theoretical model is presented to solve the transient, two-dimensional, compressible Reynolds equation for a gas bearing. The Newton-Raphson method is used on the governing nonlinear Reynolds equaion while the Galerkin’s method is employed to solve the resulting linear equations for the correction term. The numerical solution of the pressure distribution of an infinitely long, plane-wedge, slider bearing compares very well with the analytical (exact) solution. This theoretical model is then used to calculate the trajectory of a ringless piston within the cylinder of an I. C. engine under a given dynamic loading. The flexible polyhedron unconstrained minimization method is used to find the equilibrium position of the piston within the cylinder for each crankangle. It was found that a 40 mm long ringless piston can support a uniform side load of about 50 Newtons at 2000 r/min running on a gas film. However, the same piston can sustain a nonuniform side load with a much higher peak value (three to five times the uniform load) which lasts approximately 20 to 30 degrees of crankangle only. The sustainable side load by gas lubrication is much lower than the peak piston side load of conventional internal combustion engines.
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Alves, Helton do Nascimento, Benemar Alencar de Souza, and Helvio Alves Ferreira. "Banks of automatic capacitors in electrical distribution systems: a hibrid algorithm of control." Sba: Controle & Automação Sociedade Brasileira de Automatica 16, no. 1 (March 2005): 93–99. http://dx.doi.org/10.1590/s0103-17592005000100011.
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A microgenetic algorithm (MGA) in conjunction with fuzzy logic (FL) is proposed for solving the capacitor placement problem. The objective function includes economic savings obtained by energy loss reduction and peak power loss reduction in contrast with acquisition and installation costs of fixed and switched capacitors. Voltage constraints are considered. A simple and efficient method for load flow solution is used, with acceptable CPU time, even for very extensive distribution systems under full load. An approximate load-duration curve divided in different load levels is used to compute energy losses. A 104-bus test system is presented and the results are compared to the solution given by another search technique. This comparison confirms the efficiency of the proposed method which makes it promising to solve complex problems of capacitor placement in distribution feeders.
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Zhuravchak, Ruslan, Natasa Nord, and Helge Brattebø. "Control strategy for battery-supported photovoltaic systems aimed at peak load reduction." E3S Web of Conferences 111 (2019): 05027. http://dx.doi.org/10.1051/e3sconf/201911105027.
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The use of photovoltaic (PV) technologies is one of the key means for achieving the balance between operational power demand and generation in net Zero Energy Buildings (nZEBs). However, direct use of PV power on-site is limited due to wide variability and uncertainty of PV output, the temporal mismatch between PV generation and load and other factors. Consequently, in addition to low self-consumption rates, the problem of peak grid load and peak PV feed into the grid persists. Batteries that are coupled to PV units may partially offer the solution to these problems, if operated under an intelligent control strategy. In this paper we proposed a forecast-based control strategy for battery-to-grid interaction aimed at enhancing selfconsumption and at reducing peak load. Python programming environment was used for data processing and algorithm development. Exemplification was made based on the reported hourly energy demand in one office building of 3000 m2 heated floor area located in Trondheim, Norway. Forecasting of electricity load profiles was based on the seasonal autoregressive integral moving average (SARIMA) model. For PV power forecasting, the algorithm communicated with external service – Solcast API. The search method for optimal scheduling of operational time and the extent of charging/discharging was proposed. The results showed that as opposed to conventional battery use, this control strategy allowed to achieve significantly more consistent grid interaction. It offered highly accurate battery scheduling on a day-ahead basis while utilising minimum historical data and computational resources. The algorithm may be beneficial for end-users and grid operators, and thus, it has a high potential for future integration into building energy supply systems.
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Ju, Jin San, Min Ding, Xu Dong Shi, Song Cen, Xiu Gen Jiang, and Xing Hua Chen. "Effect of Beam Height on Elastic Impact Load Subjected to Transverse Impact of Bar." Key Engineering Materials 462-463 (January 2011): 259–64. http://dx.doi.org/10.4028/www.scientific.net/kem.462-463.259.
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The procedure of beam subjected to transverse impact by bar is simulated using numerical method. The method considers the propagation of the expansion wave and shear wave in beam. The effect of beam height on elastic impact loads with different bar lengths and beam heights are investigated. With condition that the length of beam is longer than or equal to that of bar, the numerical solution shows that: when the bar length is constant, if the length of bar is shorter than the height of beam, the longer the bar, the bigger the peak value of impact force; the impact load curve consists of ascending and descending part basically; When the bar length is longer than or equal to beam height, the peak value of impact force is not related to the bar length and equal to that of bar with the same length as the beam height; the impact load curve is trapezium. The contact time is proportional to bar length and equal to the duration time of stress wave propagation in the bar for once return. If the bar length is constant, when bar length is shorter than beam height, the impact load is not related to beam height; when bar length longer than or equal to beam height, the peak value of impact force increases along with the beam height and approach to that of bar with the same length as the beam height.
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de Castro Tomé, Mauricio, Pedro H. J. Nardelli, Hafiz Majid Hussain, Sohail Wahid, and Arun Narayanan. "A Cyber-Physical Residential Energy Management System via Virtualized Packets." Energies 13, no. 3 (February 6, 2020): 699. http://dx.doi.org/10.3390/en13030699.
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This paper proposes a cyber-physical system to manage flexible residential loads based on virtualized energy packets. Before being used, flexible loads need to request packets to an energy server, which may be granted or not. If granted, the energy server guarantees that the request will be fulfilled. Each different load has a specific consumption profile and user requirement. In the proposed case study, the residential consumers share a pool of energy resources that need to be allocated by the energy server whose aim is to minimize the imports related to such a group. The proposed solution shows qualitative advantages compared to the existing approaches in relation to computational complexity, fairness of the resource allocation outcomes and effectiveness in peak reduction. We demonstrate our solution based on three different representative flexible loads; namely, electric vehicles, saunas and dishwashers. The numerical results show the efficacy of the proposed solution for three different representative examples, demonstrating the advantages and drawbacks of different allocation rules.
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Sharma, Dharmendra, Jari Rehu, Klaus Känsälä, and Heikki Ailisto. "An Automatic Aggregator of Power Flexibility in Smart Buildings Using Software Based Orchestration." Sensors 21, no. 3 (January 28, 2021): 867. http://dx.doi.org/10.3390/s21030867.
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This paper presents a software-based modular and hierarchical building energy management system (BEMS) to control the power consumption in sensor-equipped buildings. In addition, the need of this type of solution is also highlighted by presenting the worldwide trends of thermal energy end use in buildings and peak power problems. Buildings are critical component of smart grid environments and bottom-up BEMS solutions are need of the hour to optimize the consumption and to provide consumption side flexibility. This system is able to aggregate the controls of the all-controllable resources in building to realize its flexible power capacity. This system provides a solution for consumer to aggregate the controls of ‘behind-the-meter’ small loads in short response and provide ‘deep’ demand-side flexibility. This system is capable of discovery, status check, control and management of networked loads. The main novelty of this solution is that it can handle the heterogeneity of the installed hardware system along with time bound changes in the load device network and its scalability; resulting in low maintenance requirements after deployment. The control execution latency (including data logging) of this BEMS system for an external control signal is less than one second per connected load. In addition, the system is capable of overriding the external control signal in order to maintain consumer coziness within the comfort temperature thresholds. This system provides a way forward in future for the estimation of the energy stored in the buildings in the form of heat/temperature and use buildings as temporary batteries when electricity supply is constrained or abundant.
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Frantziskonis, G. "Surface Effects in Brittle Materials and Internal Length Estimation." Applied Mechanics Reviews 45, no. 3S (March 1, 1992): S62—S70. http://dx.doi.org/10.1115/1.3121392.
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The concept of state of degradation is employed as a tool to study the effect of initial material (structure) inhomogeneity and the implications of surface (skin) effects on brittle material response. The initial heterogeneity pattern and its growth under external load is studied experimentally via ultrasonic scanning measurements on prismatic simulated rock samples subjected to mechanical load. Numerical solutions are compared with the experimental results. The skin effects are also studied experimentally through the spatial variation of dissipated energy within the samples tested. In addition, microstructure considerations highlight the skin effect and its implications. The material length for the simulated rock is estimated (for load levels up to peak load) through the experimental observations which yielded 1≃0.24 inches (0.61 cm). The analytical solution of a simple problem including microstructure considerations for the same material yielded 1≃0.21 inches (0.53 cm). This paper integrates and extends the recent work of the author and co-workers.
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Lee, Eunjung, Keon Baek, and Jinho Kim. "Evaluation of Demand Response Potential Flexibility in the Industry Based on a Data-Driven Approach." Energies 13, no. 23 (December 2, 2020): 6355. http://dx.doi.org/10.3390/en13236355.
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The rapid increase in renewable energy resources has resulted in the increasing need for a demand flexibility program (DFP) from industrial load resources as a solution to oversupply and peak load spikes. However, to reasonably estimate the DR potential flexibility, the load characteristics must be analyzed and potential assessment formulas must be validated. Thus, in this study, a novel method is proposed to evaluate the DR potential flexibility of industrial loads according to a process of related load-characteristic data analysis. The proposed potential-estimation model considers frequency, consistency, and DR event operation scores during designated ramp-up and ramp-down time intervals separately. A case study was conducted by considering typical cement industry process with actual power-consumption data analysis for demonstrating the test system. The results confirm that load reduction of more than half of the usual power consumption is possible if a potential score is about 0.27 in cement industry cases. Thus, the proposed method can be used as an indicator to determine how an industrial load is adequate for obtaining a DFP while suggesting meaningful implications through industrial load-resource data analysis.
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Veic, Duje, and Wojciech Sulisz. "Impact Pressure Distribution on a Monopile Structure Excited by Irregular Breaking Wave." Polish Maritime Research 25, s1 (May 1, 2018): 29–35. http://dx.doi.org/10.2478/pomr-2018-0019.
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Abstract The problem of impact pressure distribution on a monopole structure excited by irregular breaking waves is investigated. The analysis is performed by applying a numerical model that combines potential flow model with a Navier-Stokes/VOF solution. The temporal pressure distribution is analysed for two breaking wave cases characterized by the significant difference in the steepness of the wave front. The peak impact pressures are observed in the region below the overturning wave jet where the pressure increases rapidly resulting in a peak value of the slamming coefficient equal to Cs=2π. The vertical load distribution provided by the derived model is more realistic than a rectangular shape distribution applied in engineering practice. This is because the vertical load distribution strongly depends on breaking wave shape and it is difficult to uniquely approximate such a load distribution by a rectangle.
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Berger, E. J., F. Sadeghi, and C. M. Krousgrill. "Finite Element Modeling of Engagement of Rough and Grooved Wet Clutches." Journal of Tribology 118, no. 1 (January 1, 1996): 137–46. http://dx.doi.org/10.1115/1.2837069.
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A finite element model has been developed to investigate the engagement of rough, grooved, paper-based permeable wet clutches. The finite element (Galerkin) approach was used to discretize the modified Reynolds and force balance equations, and the solution domain geometry was described using an isoparametric formulation. Surface roughness effects were modeled via the Patir and Cheng (1978) average flow model, while asperity load sharing was calculated using the Greenwood and Williamson (1966) approach. The finite element model developed, was used to investigate the effects of applied load, friction material permeability, and groove size on the engagement characteristics of wet clutches (i.e., torque, pressure, engagement time, and film thickness). The results indicate that the applied load, friction material permeability, and groove width significantly influence the engagement characteristics. Higher facing pressures increase peak torque and decrease engagement time. Higher permeability of the friction material significantly decreases engagement time but dramatically increases peak torque. Wider grooves decrease the peak torque and increase the engagement time. Groove depth does not significantly affect engagement characteristics for this model.
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Allen, James, Ari Halberstadt, John Powers, and Nael H. El-Farra. "An Optimization-Based Supervisory Control and Coordination Approach for Solar-Load Balancing in Building Energy Management." Mathematics 8, no. 8 (July 23, 2020): 1215. http://dx.doi.org/10.3390/math8081215.
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This work considers the problem of reducing the cost of electricity to a grid-connected commercial building that integrates on-site solar energy generation, while at the same time reducing the impact of the building loads on the grid. This is achieved through local management of the building’s energy generation-load balance in an effort to increase the feasibility of wide-scale deployment and integration of solar power generation into commercial buildings. To realize this goal, a simulated building model that accounts for on-site solar energy generation, battery storage, electrical vehicle (EV) charging, controllable lighting, and air conditioning is considered, and a supervisory model predictive control (MPC) system is developed to coordinate the building’s generation, loads and storage systems. The main aim of this optimization-based approach is to find a reasonable solution that minimizes the economic cost to the electricity user, while at the same time reducing the impact of the building loads on the grid. To assess this goal, three objective functions are selected, including the peak building load, the net building energy use, and a weighted sum of both the peak load and net energy use. Based on these objective functions, three MPC systems are implemented on the simulated building under scenarios with varying degrees of weather forecasting accuracy. The peak demand, energy cost, and electricity cost are compared for various forecast scenarios for each MPC system formulation, and evaluated in relation to a rules-based control scheme. The MPC systems tested the rules-based scheme based on simulations of a month-long electricity consumption. The performance differences between the individual MPC system formulations are discussed in the context of weather forecasting accuracy, operational costs, and how these impact the potential of on-site solar generation and potential wide-spread solar penetration.
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VAHDAT, IMAN, MOHAMAD PARNIANPOUR, FARHAD TABATABAI GHOMSHEH, NIMA TOOSIZADEH, and ALI TANBAKOOSAZ. "COMPARING METHODS FOR 3D INVERSE DYNAMICS ANALYSIS OF SQUAT LIFTING USING A FULL BODY LINKED SEGMENT MODEL." Journal of Mechanics in Medicine and Biology 20, no. 03 (April 2020): 2050004. http://dx.doi.org/10.1142/s0219519420500049.
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Objective: The main objective of this study was to assess the accuracy of bottom-up solution for three-dimensional (3D) inverse dynamics analysis of squat lifting using a 3D full body linked segment model. Least squares solution was used in this study as reference for assessment of the accuracy of bottom-up solution. Findings of this study may clarify how much the bottom-up solution can be reliable for calculating the joint kinetics in 3D inverse dynamics problems. Methods: Ten healthy males volunteered to perform squat lifting of a box with a load of one-tenth of their body weights. The joint moments were calculated using 110 reflective passive markers (46 anatomical markers and 64 tracking markers) and a 3D full body linked segment model. Ground reaction forces and kinematics data were recorded using a Vicon system with two parallel Kistler force plates. Three-dimensional Newton–Euler equations of motion with bottom-up and least squares solutions were applied to calculate joint moments. The peak and mean values of the joint moments were determined to check the quantitative differences as well as the time-to-peak value of the moment curves was determined to check the temporal differences between the two inverse dynamics solutions. Results: Significant differences (all [Formula: see text]-values [Formula: see text]) between the two inverse dynamics solutions were detected for the peak values of the hip (right and left sides) and L5–S1 joint moments in the lateral anatomical direction as well significant differences (all [Formula: see text]-values [Formula: see text]) were detected for the peak and mean values of the L5–S1 joint moment in all anatomical directions. Moreover, small differences (all RMSEs [Formula: see text]%) were detected between the two inverse dynamic solutions for the calculated lower body joint moments. Conclusions: The findings of this study clarified the disadvantages of the straightforward solutions and demonstrated that the bottom-up solution may not be accurate for more distal measures from the force plate (for hip and S1–L5) but it may be accurate for more proximal joints (ankle and knee) in 3D inverse dynamics analysis.
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Li, Jing, Ning Bo Wang, Ying Wei, and Qun Gu. "The Current and Solution of Wind Power Consumption for Gansu Province." Applied Mechanics and Materials 826 (February 2016): 55–60. http://dx.doi.org/10.4028/www.scientific.net/amm.826.55.
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The average wind power in China increases year by year, obviously wind power output volatility and uncertainty that makes the large-scale wind power grid to bring a lot of problem, such as peaking and frequency modulation, voltage regulator, stability, power quality problems, etc. The power structure in China is given priority with coal-fired thermal power, peaking power is relatively scarce. Lack of wind power on a large scale grid has intensified. The paper briefly analyzes the power grid network frame structure, load and power characteristics in Gansu province. Considering the measured data in 2014 of Gansu power network, intuitive shows Gansu power grid fluctuation characteristics of wind power output in different period of time, discussed the influence of wind power grid peak shaving capability. It improving the large-scale wind power access after the measures of Gansu power grid peak shaving capability.
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Dai, Xingjian, Kunpeng Wei, and Xiaozhang Zhang. "Analysis of the Peak Load Leveling Mode of a Hybrid Power System with Flywheel Energy Storage in Oil Drilling Rig." Energies 12, no. 4 (February 14, 2019): 606. http://dx.doi.org/10.3390/en12040606.
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The load frequently oscillates in large amplitude like pulses when the draw-works lift or lower in the oil well drilling rig, and that makes the diesel engine run uneconomically. A new solution for the pulse load problem is to add a motor/generator set and a flywheel energy storage (FES) unit to the diesel engine mechanical drive system to form a hybrid power system with energy storage. The storage capacity of the power and energy, and the charging-discharging operation modes are discussed for the first time. The engine power output in frequent fluctuation was measured in the oil well drilling engineering practice. The configuration and the theoretical model of the hybrid power system with energy storage and peak load leveling were established. Furthermore, 1% to 12% saving of fuel is possible for the case of single engine in the load leveling running mode compared to bi-engines in a traditional running mode for the peak load between 900 to 1200 kW and the valley load between 200 to 600 kW. The experimental verification of the load leveling with FES confirmed that the diesel engine worked more smoothly with less smoke emission. In addition, 5% to 10% more fuel was consumed in the load leveling test compared to the traditional running mode with the drive-by 800 kW diesel engine. However, 21% fuel saving was obtained in the load leveling test with the drive-by 400 kW diesel generator.
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Lan, Xiangjun, Zhihua Feng, and Fan Lv. "Stochastic Principal Parametric Resonances of Composite Laminated Beams." Shock and Vibration 2014 (2014): 1–17. http://dx.doi.org/10.1155/2014/617828.
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This paper presents a detailed study on the stochastic stability, jump, and bifurcation of the motion of the composite laminated beams subject to axial load. The largest Lyapunov exponent which determines the almost sure stability of the trivial solution is quantificationally resolved and the results show that the increase of the bandwidth facilitates the almost sure stability of the trivial response. The stochastic jump and bifurcation of the response are numerically calculated through the stationary joint probability and the results reveal that (a) the higher the excitation frequency is, the more probable the jump from the stable stationary nontrivial solution to the stable stationary trivial one is; (b) the most probable motion is around the nontrivial solution when the bandwidth is smaller; (c) the outer flabellate peak decreases, while the central volcano peak increases as the value of the excitation load decreases; and (d) the overall tendency of the response is that the probable motion jumps from the stable stationary nontrivial branch to the stable stationary trivial one as the fiber orientation angle of the first lamina with respect to thex-axis of the beam increases from zero to a smaller angle.
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Mocera, Francesco, and Aurelio Somà. "Analysis of a Parallel Hybrid Electric Tractor for Agricultural Applications." Energies 13, no. 12 (June 12, 2020): 3055. http://dx.doi.org/10.3390/en13123055.
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The field of Non-Road Mobile Machineries (NRMM) is now more than ever considering the adoption of electric systems to reduce the amount of pollutant emissions per unit of work. However, the intensity and complexity of the tasks performed by a working machine during its life is an obstacle to the widespread adoption of electric systems. Specific design solutions are required to properly split the power output of the hybrid powertrain among the different loads (wheel, power take off, hydraulic tools, etc.). In this work, a performance analysis between a traditional agricultural tractor and a proposed hybrid electric architecture of the same vehicle is shown. The comparison was performed on a set of tasks characterized on a real orchard tractor which were used to build the input signals of two different numerical models: one for the traditional diesel architecture and the other for the hybrid electric solution. The two models were tested with the same operating tasks to have a one to one comparison of the two architectures. Peak power capabilities of the hybrid solution and performance of the Load Observer energy management strategy were investigated to validate the feasibility of the proposed solution.
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Hartungi, Rusdy, and L. J. Commis. "Contribution on Improving Power Resilience in the Healthcare Facility." International Journal of Smart Grid and Sustainable Energy Technologies 1, no. 2 (December 18, 2019): 61–66. http://dx.doi.org/10.36040/ijsgset.v1i2.214.
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Focused on predicting and preventing electrical failures, this paper presents methodologies to those responsible for managing the electrical supplies in Healthcare and other similar environments. Particular attention has been directed to developing ways of exploiting the known relationships between thermal and electrical engineering disciplines as a means of monitoring and informing a timely intervention. There are two major studies presented in this paper which contrubute resilience in specific areas of Healtcare Facility. The first study is focusing on thermography, it is enhanced with an application of the finite difference method for modelling thermal performance under adverse conditions has been analysed.Thsi methos could provide a more robust solution for appraising new and existing installations. Study shows that early identification. A second study was carried out to examine the use of weather forecast-based electrical site load predictions as a possible precursor to automated load shed control which found reliable correlation between a site’s peak electrical load and the peak outside air temperature. The use of weather forecast-based electrical site load will help reducing unnecessary tripping of the power supply and this increase resilience.
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Tao, Xingyu, Heng Li, Chao Mao, Chen Wang, Jeffrey Boon Hui Yap, Samad Sepasgozar, Sara Shirowzhan, and Timothy Rose. "Developing Shuffled Frog-Leaping Algorithm (SFLA) Method to Solve Power Load-Constrained TCRTO Problems in Civil Engineering." Advances in Civil Engineering 2019 (May 2, 2019): 1–16. http://dx.doi.org/10.1155/2019/1404636.
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It is extensively acknowledged that excessive on-site electricity power load often causes power failure across a construction site and surrounding residential zones and can result in unforeseen schedule delay, construction quality problems, life inconvenience, and even property loss. However, energy management, such as power load optimization, has long been ignored in construction scheduling. This study aims to develop a modified shuffled frog-leaping algorithm (SFLA) approach in project scheduling to aid decision-makers in identifying the best Pareto solution for time-cost-resource trade-off (TCRTO) problems under the constraint of precedence, resource availability, and on-site peak electricity power load. A mathematical model including three objective functions and five constraints was established followed by the application of the modified SLFA on real-case multiobjective optimization problems in construction scheduling. The performance of SLFA was compared with that of the nondominated sorting genetic algorithm (NSGA II). The results showed that the developed new approach was superior in identifying optimal project planning solutions, which could essentially assist on-site power load-oriented schedule decision-making for construction teams.
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Dong, Hong Bo, and Gao Chao Wang. "Microstructure and Mechanical Properties of 6061 Aluminum Alloy Processed by Multi-Pass ECAE at Room Temperature." Advanced Materials Research 148-149 (October 2010): 579–85. http://dx.doi.org/10.4028/www.scientific.net/amr.148-149.579.
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In order to investigate effect of equal channel angular extrusion (ECAE) on microstructure and mechanical properties of annealed and solution-aged 6061 aluminum alloys, continuous ECAE process was carried out by physical test and finite element methods. The results show that the grains are refined with the increase of deformation; the metal flow lines cross and shear each other to form the clear boundaries. The solution-aged Al alloy does not show a monotonic increase in surface hardness with increasing passes as the annealed Al alloy does, but reaches a maximum value after the second pass and decreases successively during next two passes, which is closely related with the dislocation multiplication, recombination and annihilation. For the annealed and solution-aged Al-6061, the peak load reaches a maximum value in the second pass and fluctuates during the additional passes, which is caused by both material properties and frictions. The simulation shows that the peak load increases slowly with increasing passes, which is not in agreement with the measured value. Therefore the finite element mode using a single constitutive equation is not suitable for simulating multi-pass ECAE processing. The constitutive relations need to amend accordingly due to great changes of the mechanical properties between different passes.
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Suriya, Ponnambalam, Srikrishna Subramanian, Sivarajan Ganesan, and Manoharan Abirami. "Generation and transmission expansion management using grasshopper optimization algorithm." International Journal of Engineering Business Management 11 (January 1, 2019): 184797901881832. http://dx.doi.org/10.1177/1847979018818320.
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This article explores how generation and transmission expansion plans (GTEPs) vary and become better suited for the accessibility of smart grid technology (SGT), essentially comprising load shifting, environmental assets and cost rebates. Demand response (DR) resources in smart grids have emerged in debates on GTEP, especially with respect to compromising system security. The planned model is designed as an innovative GTEP solution with DR resources that minimize cost by decreasing the peak load of the basic plan. A chaotic grasshopper optimization algorithm (CGOA) is used to optimize the results of the proposed GTEP model.
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Topel, Monika, and Josefine Grundius. "Load Management Strategies to Increase Electric Vehicle Penetration—Case Study on a Local Distribution Network in Stockholm." Energies 13, no. 18 (September 14, 2020): 4809. http://dx.doi.org/10.3390/en13184809.
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As part of decarbonization efforts, countries are adapting their energy policies accordingly. Sweden has established ambitious energy goals, which include CO2 emissions reduction in the transport sector and high integration of renewables in the electricity sector. Coupling the two can be an enabling force towards fossil freedom. An increased share of electric vehicles is therefore a promising solution in this regard. However, there are challenges concerning the impact that a surge of electric vehicles would have on the electric infrastructure. Moreover, in Stockholm there is a shortage of power capacity due to limitations in the national transmission infrastructure, which further aggravates the situation. This paper develops a scenario-based simulation study to evaluate the impact of electric vehicle loads on the distribution grid of a Stockholm neighborhood. In this process, limiting factors and bottlenecks in the network were identified as being related to the peak power and transformer capacities for the years of 2025 and 2031. Two load management strategies and their potential to mitigate the power peaks generated from uncontrolled charging were investigated for the critical years.
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Raad, P. E., and J. W. White. "Entrance and Stationary Roughness Effects on the Load Carrying Capacity of a Wide Wedge Gas Bearing." Journal of Tribology 111, no. 1 (January 1, 1989): 41–48. http://dx.doi.org/10.1115/1.3261877.
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The objective of this work is the determination of the effects of surface roughness amplitude and inlet conditions on ultra-thin, compressible, isothermal, infinitely-wide gas bearings. The method of study is numerical in nature and consists of a second-order accurate finite difference solution of the Reynolds equation of lubrication without molecular slip for a range of bearing numbers spanning six orders of magnitude. The motivation for this work comes from the magnetic disk drive industry where ever decreasing head flying heights are being sought to increase the recording density. Past studies by these authors of the infinitely-wide air bearing with stationary roughness have shown that, unlike in the case of a smooth bearing, the load peaks at a finite bearing number comparable to that at which current rigid disk drives operate. This suggests that it may be possible to arrange the roughness pattern in such a way as to cause the slider to separate from the hard disk more rapidly, minimizing wear to both surfaces. A wedge bearing with stationary sinusoidal roughness is studied for different roughness amplitudes and two phases. It is shown that for all configurations considered, the load exhibits a peak unlike in the case of the smooth bearing where the load monotonically reaches a peak at an infinite gas bearing number. Two rough sliders with flat tapers smoothly attached to their leading edge are also studied to answer questions regarding the role that the inlet condition plays in the resulting magnitude and behavior of the generated load. The leading taper allows the bearing to dynamically determine the entrained flow rate and maximum pressure as well as to self prescribe the inlet condition at the leading edge of the first roughness wave. The inlet conditions prescribed by the developing flow in the flat taper region still give rise to a peak in the load. The addition of the smooth taper, however, causes an overall decrease (increase) in the load when the roughness waves are entirely above (below) the plane of the taper compared to the results of the rough bearing with no taper. It is demonstrated that all the considered roughness patterns result in a peak load at a finite bearing number. Of special interest are two bearing configurations: one composed of a smooth taper followed by a transversely roughened slider and the other is a rough slider with a transverse roughness pattern whose slope at the inlet of the bearing is negative. Both are shown to achieve a maximum lifting force at low bearing numbers, providing rapid separation while alleviating the narrow rail manufacturing problem.
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Zhang, Bo, Bicheng Huang, and Zhongxian Wang. "Study on Capacity Distribution of Optimal Configuration Ratio of Urban Replenishment Station of Electric Vehicles." Recent Advances in Electrical & Electronic Engineering (Formerly Recent Patents on Electrical & Electronic Engineering) 13, no. 1 (February 20, 2020): 119–25. http://dx.doi.org/10.2174/1874476105666190830111228.
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Background: This paper deeply studies the influence of the capacity distribution of urban charging and replacing power stations on the distribution network and gives the optimal solution. Objective: The optimal configuration scheme of the charging and replacing station has been given to reduce the impact of the charging and replacing station on the distribution network. Methods: First, the Monte Carlo simulation method is used to extract the influencing factors. The probability load models of the battery replacement station, the slow charging station and the fast charging station are established respectively. The capacity distribution is represented by three different types of charging and switching station configuration ratios. Furthermore, the impact of the charging and replacing power station on the economics and safety of the distribution network is analyzed. Different from other literature, the “peak-filling” model with “minimum peak load”, “maximum valley load” and “minimum peak-to-valley difference” is established, and then PSO is adopted. Results: Finally, the actual configuration is used to compare and analyze the four configuration schemes to prove the superiority of the optimization scheme. Conclusion: Three models have different key influencing factors, so that the electric vehicle load forecasting is more targeted and accurate. The results show that more battery replacement stations can reduce the impact of EV charging on the distribution network, and the construction of the supply replenishment should be based on the construction of the power station.
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Forsström, Antti, Yuriy Yagodzinskyy, and Hannu Hänninen. "Hydrogen effects on mechanical performance of nodular cast iron." Corrosion Reviews 37, no. 5 (September 25, 2019): 441–54. http://dx.doi.org/10.1515/corrrev-2019-0007.
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AbstractThe KBS-3 method for long-term disposal of spent nuclear fuel is designed with an external self-standing copper shell, which provides the most important barrier against corrosion and escape of radionuclides, and an internal nodular cast iron insert, which provides the load-bearing structure against external loads. The material intended for the load-bearing insert is ferritic nodular cast iron EN 1563 grade EN-GJS-400-15U. In this paper, hydrogen uptake and sensitivity to hydrogen-induced cracking of the cast iron were studied using tensile testing under continuous electrochemical charging in 1 N H2SO4 solution. Hydrogen uptake was measured by using the thermal desorption method. It was found that the hydrogen desorption profile manifests three distinct peaks at initial locations of 400, 500, and 700 K with a heating rate of 6 K/min. Plastic deformation results in a remarkable increase of the 400 K peak, which indicates hydrogen uptake during deformation. In the constant extension rate tests (CERT) and the constant load tests (CLT), electrochemical hydrogen charging reduced markedly the elongation to fracture and time to fracture, respectively. In CLT, hydrogen charging increased dramatically the creep rate at the applied load of about 0.7 yield stress. Ligaments between the graphite nodules exhibit brittle cleavage facets in the presence of hydrogen, while the ligaments show a characteristic ductile appearance of shear and small dimples when testing in air or distilled water. The obtained results are discussed in terms of the known mechanisms of hydrogen-induced cracking and the role of the graphite nodules in the embrittlement of ductile cast iron.
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Tan, Mao, Hua-li Yang, Bin Duan, Yong-xin Su, and Feng He. "Optimizing Production Scheduling of Steel Plate Hot Rolling for Economic Load Dispatch under Time-of-Use Electricity Pricing." Mathematical Problems in Engineering 2017 (2017): 1–13. http://dx.doi.org/10.1155/2017/1048081.
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Time-of-Use (TOU) electricity pricing provides an opportunity for industrial users to cut electricity costs. Although many methods for Economic Load Dispatch (ELD) under TOU pricing in continuous industrial processing have been proposed, there are still difficulties in batch-type processing, since power load units are not directly adjustable and nonlinearly depend on production planning and scheduling. In this paper, for hot rolling, a typical batch-type and energy intensive process in steel industry, a production scheduling optimization model for ELD is proposed under TOU pricing, in which the objective is to minimize electricity costs while considering penalties caused by jumps between adjacent slabs. A NSGA-II based multiobjective production scheduling algorithm is developed to obtain Pareto optimal solutions, and then TOPSIS based multicriteria decision-making is performed to recommend an optimal solution to facilitate field operation. Experimental results and analyses show that the proposed method cuts electricity costs in production, especially in case of allowance for penalty score increase in a certain range. Further analyses show that the proposed method has effect on peak load regulation of power grid.
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Kim, Hye Ji, Hosung Jung, Young Jun Ko, Eun Su Chae, Hyo Jin Kim, Il Seo Hwang, Jae-Haeng Heo, and Jong-young Park. "Cooperative Operation Schedules of Energy Storage System and Demand Response Resources Considering Urban Railway Load Characteristic under a Time-of-Use Tariff." Journal of Electrical Engineering & Technology 16, no. 3 (February 15, 2021): 1273–84. http://dx.doi.org/10.1007/s42835-021-00670-3.
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AbstractThis paper proposes an algorithm for the cooperative operation of air conditioning facilities and the energy storage system (ESS) in railway stations to minimize electricity. Unlike traditional load patterns, load patterns of an urban railway station can peak where energy charge rates are not high. Due to this possibility, if applying the traditional peak-reduction algorithm to railway loads, energy changes can increase, resulting in higher electricity bills. Therefore, it is required to develop a new method for minimizing the sum of capacity charges and energy charges, which is a non-linear problem. To get a feasible solution for this problem, we suggest an algorithm that optimizes the facility operation through two optimizations (primary and secondary). This method is applied to the air-quality change model for operating air conditioning facilities as demand-response (DR) resources in railway stations. This algorithm makes it possible to estimate operable DR capacity every hour, rather than calculating the capacity of DR resources conservatively in advance. Finally, we perform a simulation for the application of the proposed method to the operation of DR resources and ESS together. The simulation shows that electricity bills become lowered, and the number of charging and discharging processes of ESS is also reduced.
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Ciavarella, M., G. Macina, and G. P. Demelio. "On stress concentration on nearly flat contacts." Journal of Strain Analysis for Engineering Design 37, no. 6 (August 1, 2002): 493–501. http://dx.doi.org/10.1243/030932402320950116.
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Fretting fatigue can severely damage components subjected to oscillatory tangential loads, leading to a dramatic reduction in fatigue life and causing catastrophic ruptures. A conservative approach that can be used when considering the effect of stress concentration induced by fretting is to ensure that the peak stress is smaller than the fatigue limit of the material. However, this depends on details of the geometry as well as loading conditions. In the present work, the contact problem of a flat rounded punch in contact with a half-plane is considered, where a dovetail joint contact geometry is approximated and the classical Hertzian contact is retrieved in the limit. Developing the analytical results given by Ciavarella, Hills and Monno, an approximate Hertzian equivalent solution using Cattaneo superposition is obtained, leading to a simple formula to estimate the maximum tangential stress as a function of the load parameter Q/(f P) and geometric parameter a/b. The accuracy of the formula is checked numerically. The proposed formula gives a maximum error as low as 4 per cent in the case of zero bulk loads. For non-zero bulk loads an analytical solution is possible for the Hertzian case for moderate bulk. This leads to a second general formula containing the three dependencies (geometry, tangential load and bulk stress), which also gives a very good approximation for rounded flat and larger bulk loads, the error being generally well below 10 per cent.
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Pathak, Shashank, and G. V. Ramana. "A Designer’s Approach for Estimation of Nuclear-Air-Blast-Induced Ground Motion." Advances in Civil Engineering 2018 (2018): 1–12. http://dx.doi.org/10.1155/2018/3029837.
Full textAbstract:
A reliable estimate of free-field ground displacement induced by nuclear-air-blast is required for design of underground strategic structures. A generalized pseudostatic formulation is proposed to estimate nuclear-air-blast-induced ground displacement that takes into account nonlinear stress-strain behaviour of geomaterials, stress-dependent wave propagation velocity, and stress wave attenuation. This proposed formulation is utilized to develop a closed-form solution for linearly decaying blast load applied on a layered ground medium with bilinear hysteretic behaviour. Parametric studies of closed-form solution indicated that selection of appropriate constrained modulus consistent with the overpressure is necessary for an accurate estimation of peak ground displacement. Stress wave attenuation affects the computed displacement under low overpressure, and stress-dependent wave velocity affects mainly the occurrence time of peak displacement and not its magnitude. Further, peak displacements are estimated using the proposed model as well as the UFC manual and compared against the field data of atmospheric nuclear test carried out at Nevada test site. It is found that the proposed model is in good agreement with field data, whereas the UFC manual significantly underestimates the peak ground displacements under higher overpressures.
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Yang, T., and Q. S. Ye. "Elastoplastic Analysis of Circular Opening Based on a New Strain-Softening Constitutive Model and Its Engineering Application in Hydraulic Fracturing." Advances in Civil Engineering 2018 (December 10, 2018): 1–12. http://dx.doi.org/10.1155/2018/2806489.
Full textAbstract:
Constitutive effect is extremely important for the research of the mechanical behavior of surrounding rock in hydraulic fracturing engineering. In this paper, based on the triaxial test results, a new elastic-peak plastic-softening-fracture constitutive model (EPSFM) is proposed by considering the plastic bearing behavior of the rock mass. Then, the closed-form solution of a circular opening is deduced with the nonassociated flow rule under the cavity expansion state. Meanwhile, the parameters of the load-bearing coefficient and brittles coefficient are introduced to describe the plastic bearing capacity and strain-softening degrees of rock masses. When the above two parameters take different values, the new solution of EPSFM can be transformed into a series of traditional solutions obtained based on the elastic-perfectly plastic model (EPM), elastic-brittle plastic model (EBM), elastic-strain-softening model (ESM), and elastic-peak plastic-brittle plastic model (EPBM). Therefore, it can be applied to a wider range of rock masses. In addition, the correctness of the solution is validated by comparing with the traditional solutions. The effect of constitutive relation and parameters on the mechanical response of rock mass is also discussed in detail. The research results show that the fracture zone radii of circular opening presents the characteristic of EBM > EPBM > ESM > EPSFM; otherwise, it is on the contrast for the critical hydraulic pressure at the softening-fracture zone interface; the postpeak failure radii show a linear decrease with the increase of load-bearing coefficients or a nonlinear increase with the increasing brittleness coefficient. This study indicates that the rock mass with a certain plastic bearing capacity is more difficult to be cracked by hydraulic fracturing; the higher the strain-softening degree of rock mass is, the easier it is to be cracked. From a practical point of view, it provides very important theoretical values for determining the fracture range of the borehole and providing a design value of the minimum pumping pressure in hydraulic fracturing engineering.