Average Load Values Research Articles

Developing Hybrid Demand Response Technique for Energy Management in Microgrid Based on Pelican Optimization Algorithm

• A new application for newly developed Pelican Optimization Algorithm in solving energy management problem for Microgrid. • New technique for integration the demand response in Microgrid energy management. • The Microgrid energy management strategy is designed. • The optimization method considers the demand response. • Two case studies are presented. This paper proposes a new application of Pelican Optimization Algorithm (POA) for optimal Energy Management (EM) in Microgrid (MG) considering Demand Response program (DRP). To maximize the MG operator (MGO) benefit and to reduce the overall operating cost, including the cost of conventional generator fuel and power transaction cost, multi-objective optimization is formulated. To achieve the optimal operation of the MG, a Hybrid DRP is proposed, based on Incentive-based Demand response (IDR) to reduce the peak load and to ensure MG reliability. Reliability is achieved by applying the Hybrid technique to encourage customers to reduce their consumption during peak hours. Applying the conventional IDR (CIDR) for optimal operation leads to customers curtailments to be in off-peak hours. Also instead of using predetermined or specifying fixed hours as peak hours, the proposed hybrid DR technique is a dynamic technique based on the load profile and the average load value. Furthermore, Peak reduction percentage (PRP) was employed to show MG's reliability enhancement. Two distinct MG test systems are examined; the effectiveness of the proposed hybrid dynamic demand response (HDDR) with the proposed POA is demonstrated by comparing its simulation results to those of well-known metaheuristics and newly developed algorithms. According to HDDR with POA technique results, a total reduction in peak hours’ load is about 14.6% in the first test system and 7.6% in the second test system. The results indicate that the POA has superiority in solving the EM problem.

Flexural response of TRM subjected to low-velocity impact loads: Experimental and analytical study

A constitutive approach to investigate the flexural impact performance of textile-reinforced mortar (TRM) is presented in this study. Experiments were performed under three-point bending conditions on a drop-weight impact system at 1, 2, 3, 4, and 4.5 m/s. Experimental results showed that the differences in peak load from 4.5 to 1 m/s were 1.964 kN (for BTRM-4) and 2.191 kN (for BTRM-6), and in energy absorption from 4.5 m/s to 1 m/s incident velocities were 2.66 J (for BTRM-4) and 2.98 J (for BTRM-6). Additionally, analytical modeling of experimental results was performed to identify the correlation between the experimental and analytical results. The parameters for a strain-hardening material model were obtained by using closed-form equations. The prepared model could reproduce a tripartite load-displacement response related to pre-cracking and post-cracking behavior. The results also verified that the best agreement between the analytical model and experimental data was achieved by considering scattering, softening, and reinforcement waviness in cement matrix under different loadings. The tensile properties of the tested samples were predicted by using an inverse algorithm and model parameters. Notably, the parametric model overpredicted the simulated three stages of TRM composites. Results could be used as average load values in the structural design and analysis of cement-based material composites under different impact loads.

Bioactive Hydrogels: Design and Characterization of Cellulose-Derived Injectable Composites.

Cellulose represents a low cost, abundant, and renewable polysaccharide with great versatility; it has a hierarchical structure composed of nanofibers with high aspect ratio (3–4 nm wide, hundreds of μm long). TEMPO-mediated oxidation represents one of the most diffused methods to obtain cellulose nanofibers (CNFs): It is possible to obtain physically crosslinked hydrogels by means of divalent cation addition. The presence of inorganic components, such as calcium phosphates (CaP), can improve not only their mechanical properties but also the bioactivity of the gels. The aim of this work is to design and characterize a TEMPO-oxidized cellulose nanofibers (TOCNFs) injectable hydrogel embedded with inorganic particles, CaP and CaP-GO, for bone tissue regeneration. Inorganic particles act as physical crosslinkers, as proven by rheological characterization, which reported an increase in mechanical properties. The average load value registered in injection tests was in the range of 1.5–4.4 N, far below 30 N, considered a reasonable injection force upper limit. Samples were stable for up to 28 days and both CaP and CaP-GO accelerate mineralization as suggested by SEM and XRD analysis. No cytotoxic effects were shown on SAOS-2 cells cultured with eluates. This work demonstrated that the physicochemical properties of TOCNFs-based dispersions could be enhanced and modulated through the addition of the inorganic phases, maintaining the injectability and bioactivity of the hydrogels.

The Effect of Material Type and Location of an Orthodontic Retainer in Resisting Axial or Buccal Forces.

The purpose of this study was to investigate the effect of retainer material and retainer position on a tooth to resist movement of the tooth in a simulation model. Bidirectional continuous glass fiber-reinforced composite (FRC) retainers and control retainers of steel wires were tested. The FRC retainers had a polymer matrix of bisphenol-A-glycidyldimethacrylate (bis-GMA) and poly(methylmethacrylate) (PMMA), and it was cured with a photoinitiator system. The retainers were adhered to a lower jaw Frasaco model in two different positions. Resistance against the movement of one tooth was measured from two directions. The average load values within the FRC retainer groups were higher than within the metal retainer groups. The load values for the groups loaded from the axial direction were higher than those loaded from the buccal direction. FRC retainers, which were located 1–2 mm from the incisal edge, showed higher load values than those located 4–5 mm from the incisal edge. There was a significant difference in load values between FRC retainers and metal retainers (p < 0.01). The wire position and the direction of force also had significant effects (p < 0.01). There were no significant differences between metal retainer groups. The results of this study suggest that metal retainers are more flexible, allowing for tooth movements of larger magnitude than with FRC retainers.

Finite-element analysis and optimization of the mechanical properties of polyetheretherketone (PEEK) clasps for removable partial dentures

PurposePolyetheretherketone (PEEK), a high-strength, aesthetic, and non-allergic thermoplastic polymer, recently became a candidate for replacing metallic components in dental prosthesis. However, as PEEK is flexible, the need for retention presents a key challenge in terms of its clinical application. In this study, clasps prepared using PEEK were optimized and evaluated to provide the mechanical properties required by dentures. MethodsSeventy-two three-dimensional rod-shape models, based on four thickness/width ratios, three base widths, and six taper ratios were created. These models were analyzed using finite-element methods to determine which modified clasp arm shape provided the most appropriate mechanical properties. Three shape-optimized PEEK specimens and one standard-shape Co–Cr alloy specimen were then fabricated. Constant-displacement fatigue testing was performed to calculate load values and deformations after ten years of clinical use. ResultsShape optimization indicated a maximum stress concentration that was consistently located at the base of the specimen, a correlation between mean load values and thickness that was greater than that with the width, and a correlation between taper ratio and mean load values. Fatigue testing showed that although PEEK exhibited significantly lower average load values than the Co–Cr alloy, these were sufficient for clinical use. All specimens exhibited significant deformation during the first period of cycling; however, there was no significant difference in the deformation between the two materials after fatigue testing. ConclusionsPEEK exerts fewer stresses on abutments compared to standard-alloy clasps, provides adequate retention, and satisfy aesthetic demands, indicating that PEEK presents a promising alternative to conventional metal clasps.

Fatigue resistance of yttria-stabilized tetragonal zirconia polycrystal clasps for removable partial dentures.

With the rapid development of computer-aided design/computer-aided manufacturing (CAD/CAM) systems, the application of zirconia in removable partial dentures is expected to expand. Clasps composed of zirconia should improve esthetics without inducing the risk of metal allergy. The aim of this study was to examine the fatigue resistance of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) clasps for removable partial dentures. Yttria-stabilized tetragonal zirconia polycrystal and cobalt-chromium (Co-Cr) alloy were prepared using CAD/CAM systems. Specimens were either of the semicircular type or of the flat type, with cross-sectional areas of taper ratios of 0.50, 0.75, and 1.00. All specimens were tested using the cantilever test and the constant displacement fatigue test, and data were analyzed using ANOVA. During the cantilever test, the maximum displacement prior to fracture was greater than the required undercut, and the semicircular-type specimen exhibited a higher fracture load than the flat type. None of the specimens displayed permanent deformation and showed almost the same degree of deformation after fatigue testing. A lower taper ratio was associated with lower average load values and greater displacement. Within the limitations of this study, it was possible to conclude that Y-TZP provides the required undercut and adequate retentive force for removable partial denture clasps. Additionally, Y-TZP and Co-Cr alloy had almost the same degree of deformation even after the simulated lifespan of removable partial dentures.

Evaluation of articular disc loading in the temporomandibular joints after prosthetic and pharmacological treatment in model studies.

Temporomandibular joint dysfunction is often related to excessive load in the stomatognathic system. The objective of the model tests, using numeric calculations, was to assess the articular disc loads in the temporomandibular joints after prosthetic and pharmacological treatment of functional disorders of the masticatory organ. The study involved 10 patients, aged 21-48 years, of both sexes, randomly selected from a group of 120 patients treated with relaxation occlusal splints (60 patients, group I) and intramuscular injection of botulinum toxin type A (60 patients, group II), suffering from temporomandibular joint dysfunction with the dominant muscle component. In all subjects, a specialized functional examination was carried out. Treatment groups: occlusal splint therapy (group I) and intramuscular injection of botulinum toxin type A (group II). An assessment of the loads of 4 disc zones of the temporomandibular joints was carried out based on the results of clinical studies (phase I of the study), and numeric model tests (phase II). In the representatives of the study groups (5 patients in each group), measurements of occlusal forces and an evaluation of tension of the masseter and temporalis muscle were performed. The results of the average load values for all evaluated zones of the right and left articular disc differ in a statistically significant way in favor of group II, with the exception of the external mid part of the discs. In the case of the anterior of the right disc, the load was lower in patients belonging to group I than in those obtained in group II. Botulinum toxin type A significantly reduces the loads within the temporomandibular joints, generated by masseter muscle hypertonia.

Study on Power Loss Reduction Considering Load Variation with Large Penetration of Distributed Generation in Smart Grid

With the increasing of penetration of distributed in the smart grid, the problems that the power loss increasing and short circuit capacity beyond the rated capicity of circuit breaker will become more serious. In this paper, a methodology (Modified BPSO) is presented for network reconfiguration which is based on hybrid approach of Tabu Search and BPSO algorithms to prevent the local convergence and to decrease the calculation time using double fitnesses to consider the constraints. Moreover, an average load simulated method (ALS method) load variation considered is proposed that the average load value is used to instead of the actual load to calculation. Finally, from a case study, the results of simulation certify the approaches will decrease drastically the losses and improve the voltage profiles obviously, at the same time, the short circuit capacity is also decreased into less the shut-off capacity of circuit breaker. The power losses won’t be increased too much even if the short circuit capacity constraint is considered; voltage profiles are better with the constraint of short circuit capacity considering. The ALS method is simple and calculated time is speed.

Modelling dental implant extraction by pullout and torque procedures

Dental implants extraction, achieved either by applying torque or pullout force, is used to estimate the bone–implant interfacial strength. A detailed description of the mechanical and physical aspects of the extraction process in the literature is still missing.This paper presents 3D nonlinear dynamic finite element simulations of a commercial implant extraction process from the mandible bone. Emphasis is put on the typical load-displacement and torque-angle relationships for various types of cortical and trabecular bone strengths. The simulations also study of the influence of the osseointegration level on those relationships. This is done by simulating implant extraction right after insertion when interfacial frictional contact exists between the implant and bone, and long after insertion, assuming that the implant is fully bonded to the bone. The model does not include a separate representation and model of the interfacial layer for which available data is limited.The obtained relationships show that the higher the strength of the trabecular bone the higher the peak extraction force, while for application of torque, it is the cortical bone which might dictate the peak torque value. Information on the relative strength contrast of the cortical and trabecular components, as well as the progressive nature of the damage evolution, can be revealed from the obtained relations. It is shown that full osseointegration might multiply the peak and average load values by a factor 3–12 although the calculated work of extraction varies only by a factor of 1.5.From a quantitative point of view, it is suggested that, as an alternative to reporting peak load or torque values, an average value derived from the extraction work be used to better characterize the bone–implant interfacial strength.

Control Strategy for Power Loss Reduction considering Load Variation with Large Penetration of Distributed Generation

With the increase of penetration of distribution in distribution systems, the problems of power loss increase and short-circuit capacity beyond the rated capacity of the circuit breaker will become more serious. In this paper, a methodology (modified BPSO) is presented for network reconfiguration which is based on the hybrid approach of Tabu search and BPSO algorithms to prevent the local convergence and to decrease the calculation time using double fitness to consider the constraints. Moreover, an average load simulated method (ALS method) considering load variation is proposed such that the average load value is used instead of the actual load for calculation. Finally, from a case study, the results of simulation certify that the approaches will decrease drastically the losses and improve the voltage profiles obviously; at the same time, the short-circuit capacity is also decreased into smaller shut-off capacity of the circuit breaker. The power losses will not be increased too much even if the short-circuit capacity constraint is considered; voltage profiles are better with the constraint of short-circuit capacity considered. The ALS method is simple and the calculation time is fast.

Accelerating Effects of Cyclic Creep Due to the Alternative Load Compared with Constant Load for CD 304L

In this paper, by using a series of uniaxial tests, accelerating effects of cyclic creep due to the alternative load are compared with constant load creep behavior of CD 304L. Austenitic stainless steel 304L is used mostly in power generation and petrochemical industries due to its high temperature creep-fatigue resistance. Test samples have been obtained from cold drawn bars and the material conforms to ASTM A276-05A specifications. Uniaxial tests have been carried out at temperatures of 687, 717, and 737°C under constant and alternating loads. The effects of alternating load and the hold time on the mechanical behavior of the material and fatigue or creep damage values have been studied. The results show the strong interaction between these two damage mechanisms. It has been observed that due to the high temperature level, creep damage is dominant even in tests with very short hold times. Also, it has been shown that by increasing the hold time, the creep strain rate increases and consequently, the creep lifetime reduces. Most importantly, the results highlight the major effect of the alternating loads in increasing creep strain rate and reducing the creep lifetime compared with the constant load tests with the same average stress. In other words, the creep lifetime under alternating load is much shorter than the creep lifetime at constant load test carried out with the average load value.

Forecasting residential air conditioning loads

A doubly censored Tobit model is used to forecast hourly air-conditioner usage for individual households. The model worked well over a wide range of temperatures, 9–38°C, making it possible to accurately forecast the electricity load for a variety of demand response applications including operational reserves for renewable energy integration. Individual models are simulated and summed to obtain aggregate forecasts and confidence intervals. The model allows for correlation between the individual shocks that occur in a region. This approach gives substantially more accurate results than the moving average method typically used for forecasting and measuring direct load control. Applying the model to data from three U.S. utilities produced mean square error values from 0.027 to 0.041 with average load values per customer ranging from 0.49 to 0.62kW.

Study on Runoff Pollution Load Model

Along with the development of JiuZhai valley tourism scenic spots increasing at the same time, and the ecological environment is also with the change, how much of the change of ecological environment must be given. The TP emissions non-point source is one of the important indexes of each branch road and plank road be given. But the results is discrete, if use the current calculation model. Need a lot of data,For this，surface runoff load model is put forward based on the average load value. Through the comparative analysis, this model lead to specific areas of non-point pollutant average load value according to some small amount of water quality monitoring data. Not only eliminates random character, but also to improve the operability. Non-point source area highway TP emission load of jiuzhai valley is given by the model.