Kernel solver design of FPGA-based real-time simulator for active distribution networks

The field-programmable gate array (FPGA)-based real-time simulator takes advantage of many merits of FPGA, such as small time-step, high simulation precision, rich I/O interface resources, and low cost. The sparse linear equations formed by the node conductance matrix need to be solved repeatedly within each time-step, which introduces great challenges to the performance of the real-time simulator. In this paper, a fine-grained solver of the FPGA-based real-time simulator for active distribution networks is designed to meet the computational demand. The framework of the solver, offline process design on PC and online process design on FPGA are proposed in detail. The modified IEEE 33-node system with photovoltaics is simulated on a 4-FPGA-based real-time simulator. Simulation results are compared with PSCAD/EMTDC under the same conditions to validate the solver design

Fault diagnosis for rotating machinery based on multi-differential empirical mode decomposition

The fault diagnosis of rotating machinery has crucial significance for the safety of modern industry, and the fault feature extraction is the key link of the diagnosis process. As an effective time-frequency method, Empirical Mode Decomposition (EMD) has been widely used in signal processing and feature extraction. However, the mode mixing phenomenon may lead to confusion in the identification of multi frequency signals and restricts the applications of EMD. In this paper, a novel method based on Multi-Differential Empirical Mode Decomposition (MDEMD) was proposed to extract the energy distribution characteristics of fault signals. Firstly, multi-order differential signals were deduced and decomposed by EMD. Then, their energy distribution characteristics were extracted and utilized to construct the feature matrix. Finally, taking the feature matrix as input, the classifiers were applied to diagnosis the existence and severity of rotating machinery faults. Simulative and practical experiments were implemented respectively, and the results demonstrated that the proposed method, i.e. MDEMD, is able to eliminate the mode mixing effectively, and the feature matrix extracted by MDEMD has high separability and universality, furthermore, the fault diagnosis based on MDEMD can be accomplished more effectively and efficiently with satisfactory accuracy

Research on flux of dry atmospheric falling dust and its characterization in a subtropical city, Guangzhou, South China

Guangzhou is the central city in the Pearl River Delta (PRD), China, and is one of the most polluted cities in the world. To characterize the ambient falling dust pollution, two typical sampling sites: urban (Wushan) and suburban (University Town) areas in Guangzhou city were chosen for falling dust collection over 1 year at time intervals of 1 or 2 months. The flux of dry deposition was calculated. In addition, mineral composition and morphology of atmospheric falling dust were studied by X-ray diffraction, scanning electron microscopy, and microscopic observation. The results revealed that the dust flux in Guangzhou city was 3.34–3.78 g/(m2 month) during the study period. The main minerals in the dust were quartz, illite, calcite, kaolinite, gypsum, plagioclase, dolomite, and amorphous matter. The morphological types included grained and flaky individual minerals, chain-like aggregates, spherical flying beads, and irregular aggregates, with the chain-like and spherical aggregates indicators of industrial ash. The major dusts were derived from industrial and construction activities. The gypsum present in the dust collected in winter season was not only derived from cement dust but may also have originated from the reaction of calcic material with sulfuric acids resulting from photooxidation of SOx and NOx, which confirmed serious air pollution due to SOx and NOx in Guangzhou. The abatement of fossil fuel combustion emissions and construction dust will have a significant beneficial effect on dust reduction

Efficacy of 1% fipronil dust of activated carbon against subterranean termite Coptotermes formosanus Shiraki in laboratory conditions

Toxicity and horizontal transmission of 1% fipronil dust of activated carbon were measured using the subterranean termite Coptotermes formosanus Shiraki in laboratory conditions. 1% fipronil dust of activated carbon has delayed toxicity towards C. formosanus compared with 0.5% fipronil dust of French chalk; knockdown times KT50 and KT90 were delayed by >9 and >15 h respectively. Furthermore, 1% fipronil dust of activated carbon showed excellent primary and secondary horizontal transfer levels. In primary horizontal transfer, recipient mortalities reached 100% by 24, 48 and 72 h at donor-recipient ratios of 1:1, 1:5 and 1:10, respectively. High transfer efficacies were also found if donor-recipient ratios were greatly increased: mortality reached 100% at 9 d at ratio 1:25 and >90% at 12 d at 1:50. In secondary horizontal transfer, the toxicant transmitting ability of C. formosanus was greater when the primary horizontal transfer ratio was lower, and the highest transfer efficacy was found with a donor-recipient ratio of 1:1 - recipient mortalities reached 100% at 5 d and 11 d, respectively. Application of 1% fipronil dust of activated carbon overcomes the problem that that too high a concentration kills termites before they can contaminate their nestmates, while a lower concentration may not supply a sufficient dose for effective transfer from treated to untreated termites; this preparation has delayed toxicity, dose-dependent toxicity in horizontal transfer and high efficacy to control C. formosanus

A Synergistic Therapeutic Scheme for Hyperglycemia and Nephrotic Disorders in Diabetes

We previously demonstrated that the utilization of an electrospun scaffold could boost functional outputs of transplanted islets. In this study, we aim to develop a drug-eluting scaffold with a payload of pioglitazone to simultaneously rein in hyperglycemia and recoup lost renal functions in diabetic mice that underwent islet transplantation. The in vivo proliferation of islets was measured by a non-invasive bio-imaging technology whereas the blood insulin, blood glucose and renal proteins were assayed. The local stimulation of transplanted islets by pioglitazone saw an accelerated in vivo proliferation without apoptosis caused by the drug-eluting scaffold. In addition, pioglitazone contributed to an increased secretion of insulin and C-peptide 2, giving rise to an accelerated rein-in of hyperglycemia and enhanced tolerance of sudden oral glucose challenge. Moreover, the accelerated decrease of blood creatinine, urine creatinine and blood urea nitrogen suggested that pioglitazone contributed to the recovery of renal functions compromised by diabetes. Our bioengineering strategy effectively ameliorated hyperglycemia and associated nephrotic disorders, and shed a new light on an engineering approach to combat diabetes

Evaluation of Direct Diode Laser Deposited Stainless Steel 316L on 4340 Steel Substrate for Aircraft Landing Gear Application

300M steel is used extensively for aircraft landing gears because of its high strength, ductility and toughness. However, like other high-strength steels, 300M steel is vulnerable to corrosion fatigue and stress corrosion cracking, which can lead to catastrophic consequences in the landing gear. Stainless steels offer a combination of corrosion, wear, and fatigue properties. But for an aircraft landing gear application a higher surface hardness is required. A laser cladding process with fast heating and cooling rates can improve the surface hardness. AISI 4340 steel is used as a lower cost alternative to 300M due to its similar composition. In this study, the influence of laser cladding process parameters, shield gas, and composition of the deposition and dilution zone has been investigated. The microstructures and composition analysis were evaluated by Scanning Electron Microscopy (SEM) and Optical Microscopy. The deposition hardness varies from 330HV to 600HV.Mechanical Engineerin

Calcium Oxalate Induces Renal Injury through Calcium-Sensing Receptor

Objective. To investigate whether calcium-sensing receptor (CaSR) plays a role in calcium-oxalate-induced renal injury. Materials and Methods. HK-2 cells and rats were treated with calcium oxalate (CaOx) crystals with or without pretreatment with the CaSR-specific agonist gadolinium chloride (GdCl3) or the CaSR-specific antagonist NPS2390. Changes in oxidative stress (OS) in HK-2 cells and rat kidneys were assessed. In addition, CaSR, extracellular signal-regulated protein kinase (ERK), c-Jun N-terminal protein kinase (JNK), and p38 expression was determined. Further, crystal adhesion assay was performed in vitro, and the serum urea and creatinine levels and crystal deposition in the kidneys were also examined. Results. CaOx increased CaSR, ERK, JNK, and p38 protein expression and OS in vitro and in vivo. These deleterious changes were further enhanced upon pretreatment with the CaSR agonist GdCl3 but were attenuated by the specific CaSR inhibitor NPS2390 compared with CaOx treatment alone. Pretreatment with GdCl3 further increased in vitro and in vivo crystal adhesion and renal hypofunction. In contrast, pretreatment with NPS2390 decreased in vitro and in vivo crystal adhesion and renal hypofunction. Conclusions. CaOx-induced renal injury is related to CaSR-mediated OS and increased mitogen-activated protein kinase (MAPK) signaling, which subsequently leads to CaOx crystal adhesion

Microstructural Characterization of Diode Laser Deposited Ti-6Al-4V

Laser Direct Metal Deposition (DMD) is an effective approach to manufacturing or repairing a range of metal components. The process is a layer-by-layer approach to building up a three dimensional solid object. The microstructure influences mechanical properties of the deposited parts. Thus, it is important to understand the microstructural features of diode laser deposited parts. This paper presents a microstructure analysis of a diode laser deposited Ti-6Al-4V onto a Ti-6Al-4V substrate. laser deposited parts. This paper presents a microstructure analysis of a diode laser deposited Ti-6Al-4V onto a Ti-6Al-4V substrate

Asynchronous multi-rate method of real-time simulation for active distribution networks

The real-time simulation of active distribution networks (ADNs) can provide an accurate insight into transient behaviours, but faces challenges in simulation efficiency and flexibility brought by larger system scales and wider time-scale ranges. This paper presents an asynchronous multi-rate (AMR) method and design for the real-time simulation of large-scale ADNs. In the proposed method, the entire ADN was decoupled into different subsystems according to accuracy requirements, and optimized time-steps were allocated to each subsystem to realize a fully distributed simulation. This not only alleviated the time-step coordination problem existing in multi-rate real-time simulations, but also enhanced the flexible expansion capabilities of the real-time simulator. To realize the AMR real-time simulation, a multi-rate interfacing method, synchronization mechanism, and data communication strategy are proposed in this paper, and their hardware design is also presented in detail. A modified IEEE 123-node system with photovoltaics and wind turbine generators was simulated on a 3 field-programmable gate arrays (FPGAs)-based AMR real-time simulator. The real-time results were captured by the oscilloscope and verified with PSCAD/EMTDC, which demonstrated the superiority in simulation flexibility and accuracy compared with the synchronous multi-rate (SMR) method