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Stress field around graphene nanoplates coated carbon fiber strand reinforced in polymer matrix
摘要： Photoelasticity method was used to map the stress field around the graphene nanoplates (GnPs) coated carbon fiber strand reinforced in a polymer matrix. Carbon fiber strand (0.4 mm diameter, containing 40 carbon fibers) was considered. The composite was subjected to diametrical compression. The models were loaded under partial edge compression having 0o, 45o and 90o orientation of fiber strand with respect to loading axis. Typical isochromatic fringe patterns were observed using circular polariscope which indicated that GnPs coated carbon fiber strand inferred the direction of isochromatics. Stress concentration near the fiber region was observed. The isochromatics were slightly bent towards fiber strand which showed the strong adhesion of fiber strand with the polymer matrix. The fringe order calculated from orthotropic Mohr’s circle relevance of fringe order was different from isotropic fringe order. The isochromatic fringe pattern for composite with 0o fiber orientation was almost similar to pure epoxy. This showed that the compressive behavior of fabricated 0o oriented GnPs coated carbon fiber strand composite was almost similar to pure epoxy. The calculated values of stresses at the center of the disc showed that composite with 0o orientation of fiber strand was most effective in stress sharing. The calculation of stress fringe value for 45o orientation of fiber strand showed that aligning fiber strand at 45o doesn’t represent the case of pure shear in fiber reinforced composites. However, the deviation from pure shear was very less
关键词： Isochromatic fringes,Compressive load.,Photoelasticity,Epoxy resin,Graphene nanoplates
更新于2025-09-23 15:22:29
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Integration of Solar PV with Low-Voltage Weak Grid System: using Maximize-M Kalman Filter and Self-tuned P&O Algorithm
摘要： This paper introduces a novel 'self-tuned perturb and observe (P&O)' (SPO) algorithm for quick maximum power point tracking (MPPT) and a novel maximize-M Kalman filter (MMKF) based control technique for optimal operation of 'grid-integrated solar PV system, where linear/nonlinear loads are attached at PCC (Point of Common Coupling)'. Proposed SPO is the improved form of perturb and observe (P&O) algorithm, where inherent problems of traditional P&O like steady-state oscillation, slow dynamic responses and fixed step size issues, are successfully mitigated. Therefore, SPO tracks maximum power peak (MPP) very rapidly and it very accurately extracts maximum power from the PV array. The extracted power is used to meet the active power requirement of loads, and after meeting the load demand, the excess power is supplied to the grid. During power feeding, the power quality and power management are maintained by the MMKF based control technique. In control strategy, the MMKF is used for fundamental harmonic component extraction from the grid voltage and load current, even when the grid voltage is characterized by adverse situations, like sag, swell, harmonic distortion, DC offset etc. Here, the SPO MPPT algorithm and MMKF based control techniques, are tested on a developed prototype. The efficient and reliable performances of SPO MPPT algorithm and MMKF based control algorithm, in dynamic as well as in steady-state condition, are demonstrated under insolation variation conditions, nonlinear loading, as well as in different grid disturbances such as over-voltage, under-voltage, phase imbalance, harmonics distortion in the grid voltage etc.
关键词： MPPT,Solar PV,MMKF,Power quality,Nonlinear Load,SPO
更新于2025-09-23 15:22:29
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White light interferometry and MountainsMap? - case studies in static load capacity of bearings and surface finish optimisation of orthotic knee joints
摘要： This paper deals with two case studies demonstrating the combined use of white light interferometry and MountainsMap? software to: 1) accurately measure indentation diameters on race elements with an accuracy of a 1/100th of a micrometer and to examine static load capacity of bearings compared to the industry standard. In this case study, static load capacity of the ball bearings was shown to be 31% lower than that specified by ISO and ANSI/ABMA bearing standards; 2) characterise machined surfaces with 2D and 3D parameters, with the goal of producing optimal surface finish on orthotic knee joints used by Cerebral Palsy patients. In this case study, 2D roughness parameters Ra, Rq, Rp, Rz, and 3D roughness parameters Sa, Sq, Sp, Sz, were improved by 34%, 31%, 8%, 20%, and 36%, 33%, 6%, 6% respectively. Both case studies demonstrate the significance of modern topography techniques in enhancing the measurement accuracy of surface characteristics.
关键词： robust design,MountainsMap?,surface roughness,signal-to-noise (S/N) ratio,interferometry,WLI,static load capacity,white light,ball bearing indentations
更新于2025-09-23 15:22:29
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[IEEE 2018 International Power Electronics Conference (IPEC-Niigata 2018-ECCE Asia) - Niigata (2018.5.20-2018.5.24)] 2018 International Power Electronics Conference (IPEC-Niigata 2018 -ECCE Asia) - Secondary-side-only Control for Smooth Voltage Stabilization in Wireless Power Transfer Systems with Constant Power Load
摘要： In recent years, wireless power transfer technology has received considerable attention because of its wide range of applications. Almost all literature focuses on resistance load or constant voltage load, but constant power load is never considered. The constant power load voltage is unstable, thus stabilization is required. In order to perform it without resorting to discontinuous operation and avoid big voltage transients, this paper proposes a control strategy for a secondary side with a single converter. It is based on the combination of synchronous rectification and symmetric phase shift, without communication with the primary side. While the primary side is not manipulated, the AC/DC converter regulates the amplitude of the secondary coil voltage and stabilizes the constant power load voltage on the DC side. In this paper, the control concept, the design and the stability analysis are provided. The proposed control is verified through experimental results both in a static scenario.
关键词： Constant Power Load (CPL),secondary-side-only,symmetric phase shift,Wireless power transfer
更新于2025-09-23 15:22:29
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Antimicrobial efficacy of photodynamic therapy on dental implant surfaces: A systematic review of in vitro studies
摘要： Background: To systematically review the literature regarding the antimicrobial effects of photodynamic therapy (PDT) on the multi-bacterial species and the possible surface alterations of the dental implants as a result of PDT. Methods: The addressed focused question was: “Does PDT show antimicrobial efficacy against multi-bacterial species colonization and result in surface alteration on dental implants?” Electronic databases including MEDLINE and EMBASE up to and including December 2018 were searched. Results: Seven studies were included. Two studies used a total of 110 titanium dental implants, while 1 study included a total of 72 zirconia dental implants. Three studies investigated the antimicrobial PDT effects on titanium discs, while 1 study used titanium plates with germanium prisms. All in-vitro studies used diode laser. Energy fluence was reported only in 2 studies. Power output and density were 100 milliwatts (mW) and 150 mW cm-2, respectively. All in-vitro studies reported the multibacterial species outcomes after the application of antimicrobial PDT. All studies showed a significant reduction in the bacterial load. Only two studies reported the outcomes of microstructural changes on the titanium surface, in which both studies did not report any significant alterations on the titanium implants or discs with the application of PDT. Conclusion: This systematic review demonstrated significant reduction in the bacterial load but inconclusive findings regarding structural alterations on the titanium surface with the use of PDT. The results of this review should be considered preliminary and further in-vitro studies with standardized laser parameters are needed to obtain strong conclusions.
关键词： systematic review,titanium surface,dental implants,photodynamic therapy,bacterial load
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE Power & Energy Society General Meeting (PESGM) - Portland, OR, USA (2018.8.5-2018.8.10)] 2018 IEEE Power & Energy Society General Meeting (PESGM) - A Multiobjective Voltage Unbalance Factor for PV Hosting Capacity with Probabilistic ZIP Load Models
摘要： This paper proposes a multiobjective voltage unbalance factor to estimate single-phase photovoltaic (PV) hosting capacity in 3-phase residential networks. This factor is derived from a combination of various components, including zero and negative-sequence voltage unbalance factors associated with the inherent variability and uncertainty of both loads and PV generation. A time-varying probabilistic ZIP load model is also incorporated in the proposed factor to characterize the uncertainty of voltage-dependent loads within each hour of a day over four seasons. The location, size and phase allocation of PV units are randomly generated. Simulation results obtained on a modified IEEE 4-bus test feeder and the IEEE European low voltage test feeder show that the developed approach can provide a better response to the hourly-varying and uncertain behaviors of loads and generation.
关键词： PV hosting capacity,voltage unbalance,power quality,probabilistic ZIP load model,Distribution system
更新于2025-09-23 15:22:29
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A spatiotemporal probabilistic model-based temperature-augmented probabilistic load flow considering PV generations
摘要： The probabilistic steady‐state forecasting of a PV‐integrated power system requires a suitable forecasting model capable of accurately characterizing the uncertainties and correlations among multivariate inputs. The critical and foremost difficulties in the development of such a model include the accurate representation of the characterizing features such as complex nonstationary pattern, non‐Gaussianity, and spatial and temporal correlations. This paper aims at developing an improved high‐dimensional multivariate spatiotemporal model through enhanced preprocessing, transformation techniques, principal component analysis, and a suitable time series model that is capable of accurately modeling the trend in the variance of uncertain inputs. The proposed model is applied to the probabilistic load flow carried out on the modified Indian utility 62‐bus transmission system using temperature‐augmented system model for an operational planning study. A detailed discussion of various results has indicated the effectiveness of the proposed model in capturing the aforesaid characterizing features of uncertain inputs.
关键词： PV generation,probabilistic load flow,operational planning,spatiotemporal correlation,steady‐state forecasting
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE PES/IAS PowerAfrica - Cape Town, South Africa (2018.6.28-2018.6.29)] 2018 IEEE PES/IAS PowerAfrica - Efficient Energy Management System Using Pir Sensor
摘要： In most developing countries like Nigeria, the demand for electrical energy outweighs the supply. Negative economic and environmental impacts are also associated with its generation, transmission, and consumption. As a result there is need for the available energy to be efficiently managed. This project designed and implemented a microcontroller based energy saver and management system. The design of the energy saver and management system was aimed at coordinating the manner of use of electrical appliances, thereby reducing energy consumption in electrical appliances (such as fan and light) and devising a means of reducing the need for human intervention in the control of electrical appliances in a residential building. The project consists of a PIC microcontroller that utilizes a PIR sensor to detect occupants’ presence in the building; it also has a light intensity detection unit used to determine the level of ambient lighting as well as a temperature sensor to determine ambient temperature. The control signal from the microcontroller was used to operate the load driver circuit to switch the appliances on or off. The results show that the designed system can reduce the level of energy consumption effectively and efficiently.
关键词： load driver circuit,appliances,temperature sensor,light intensity detection,PIC microcontroller,Energy saver and Management system
更新于2025-09-23 15:21:21
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[IEEE 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Odessa, Ukraine (2018.9.4-2018.9.7)] 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Broadband Antennas with Reactive Loads
摘要： The results of a study on the expansion of the frequency range of vibrational curved whip and loop antennas are presented. Optimal designs of these antennas with concentrated reactive loads included in the shoulders are proposed. The study was carried out for a design that appears promising for use as a microstrip antenna. It is a Z-shaped antenna of orthogonal linear polarization and loop antenna, supplemented by concentrated capacitive loads. It is shown that in order to obtain in the Z-shaped antenna and loop antenna a regime of a current close to the traveling wave regime and to obtain broadband, it is sufficient to include no more than four capacitive loads of a certain value in the antenna arm. This makes the construction of a broadband antenna and to reduce the expenditure of time and resources for its development and fabrication in comparison with known works in which it was proposed to include in the arm of the antenna a much larger number of reactive loads.
关键词： concentrated capacitive load,distribution of the complex current at the antenna,broadband antenna,standing wave voltage factor,antenna gain factor
更新于2025-09-23 15:21:21
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[IEEE 2019 International Topical Meeting on Microwave Photonics (MWP) - Ottawa, ON, Canada (2019.10.7-2019.10.10)] 2019 International Topical Meeting on Microwave Photonics (MWP) - Proposal of Photonic Analog-to-digital Conversion Using Weighted Multiwavelength Pulses and Balanced Photodetector
摘要： Nowadays, enhanced knowledge of the nature of the electricity demand is achieved through the progressively increasing deployment of smart meters and advanced data analysis techniques. One of the major challenges is to exploit this knowledge to support the introduction of strategies to modify the demand according to relevant objectives to be achieved, like users’ participation in demand response programmes. A key point for facing this challenge is to characterize the demand flexibility. In spite of many discussions about the concept of flexibility, the few mathematical definitions of flexibility available do not address the variation in time of the overall demand aggregation. This paper starts from the analysis of time-variable patterns of aggregate residential customers, ending up with suitable definitions of expected flexibility for aggregate demand. These definitions are based on assessing positive and negative pattern variations and are identified from the analysis of the collective behavior of the aggregate users. A set of results is shown for different numbers of aggregate customers, by considering different values of the averaging time step for load pattern representation.
关键词： binomial probability,customers,demand flexibility,Aggregate demand,electrical load,demand response,load variation pattern,maximum likelihood estimation
更新于2025-09-23 15:21:01