In order to investigate the size dependence of microstructure of the AlSi10Mg alloy fabricated by selective laser melting (SLM) combined with a powder bed technique, plate-shaped AlSi10Mg alloy ...samples with various widths (ranging from approximately 10mm to 0.3mm) were produced in this study. All the fabricated samples exhibited characteristic microstructural morphologies consisting of melt pools with columnar α-Al grains surrounded by fine eutectic Si particles, whereas their sample sizes had a relatively small effect on the texture and average grain size of the α-Al matrix. However, the formation of fine Si precipitates inside the columnar α-Al grains was observed more often for the smaller-sized samples, which could be a possible dominant contributor to the observed softening of the sample by reducing sample size. The obtained results were utilized for discussing the size dependence of the strength of the SLM-manufactured porous alloy samples.
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•Plate-shaped samples with various widths were fabricated via selective laser melting.•The hardness of AlSi10Mg samples slightly decreased with decreasing sample width.•The alloy sample size had a slight effect on microstructure of the α-Al matrix.•Precipitation of Si phase in α-Al matrix was enhanced by reducing the sample size.•The softening by reducing sample size is likely due to their slower cooling rate.
In the present study, we examined changes in the microstructure and mechanical properties of AlSi10Mg alloy, initially fabricated using selective laser melting (SLM) combined with a powder-bed ...system, by applying heat treatments at temperatures of either 300 or 530°C. The as-fabricated samples exhibited a characteristic microstructural morphology and {001} texture. Melt pools corresponding to the locally melted and rapidly solidified regions were found to be composed of several columnar α-Al grains surrounded by fine eutectic Si particles. A fine dislocation substructure consisting of low-angle boundaries is present within the columnar α-Al grains. At elevated temperatures, fine Si phase precipitates within the columnar α-Al phase and coarsening of the eutectic Si particles occurs. These fine Si particles inhibit grain growth in the α-Al matrix, resulting in the microstructural morphology and 001 texture observed in the heat-treated samples. The dislocation substructure disappears in the columnar α-Al grains. Furthermore, the formation of a stable intermetallic phase occurs, reaching microstructural equilibrium after long-term exposure. The as-fabricated specimen exhibits a high tensile strength of approximately 480MPa. The strength is independent of the tensile direction, that is, normal and parallel to the building direction. In contrast, the tensile ductility is found to be direction-dependent, and is therefore responsible for a fracture preferentially occurring at a melt pool boundary. The direction-dependence of the tensile ductility was not found in the specimen that had been heat-treated at 530°C. The present results provide new insights into the control of the direction-dependence of the tensile properties of AlSi10Mg alloys fabricated by SLM.
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To identify the dominant contributing factor in the anomalously high strength of Al–Si-based alloys fabricated by selective laser melting (SLM), microstructural characteristics of a ...SLM-built Al–10Si–0.3 Mg alloy (AlSi10Mg) and their changes upon annealing at elevated temperatures were investigated. The as-built AlSi10Mg alloy exhibits a peculiar microstructure comprising of a number of columnar α-Al (fcc) phase with concentrated Si in solution. Numerous nano-sized particles were observed within the α-Al matrix. At elevated temperatures, a number of Si phase (diamond structure) precipitates consumed the solute Si in the columnar α-Al phase, but the microstructure of the α-Al matrix changed slightly. After annealing at elevated temperatures, the tensile strength of the as-built AlSi10Mg alloy substantially decreased accompanied by a reduction in the strain hardening rate. The supersaturated solid solution of the α-Al phase containing numerous nano-sized particles enhanced the strain hardening, resulting in the anomalous strengthening of the SLM-built AlSi10Mg alloy. The microstructural features were formed due to rapid solidification at an extremely high cooling rate in the SLM process, which provides important insights into controlling the strength of Al–Si-based alloys fabricated by SLM.
Microstructure and mechanical properties of Al–10Si–0.4Mg (mass%) alloy (AlSi10Mg alloy) specimens fabricated using selective laser melting (SLM) combined with powder-bed system have been examined. ...Optical microscope was used to identify the characteristic scalloped microstructure derived from local melting and rapid solidification of alloy powder during SLM process. The results of microscopy observation revealed that columnar α-Al grains subdivided by eutectic fine Si particles were elongated to the solidification direction depending on the radial heat flow caused by SLM process. The observed {100} texture along the building direction was attributed to the preferential 100 growth direction of α-Al phase in liquid. On the basis of the experimental results and thermodynamic analysis, the formation process of microstructure in the fabricated sample was discussed. The tensile strength of the fabricated specimen is 480 MPa, which is independent of the specimen geometry associated with the building direction, whereas the specimen tensile-deformed normal to the building direction exhibits a lower tensile ductility, which would be responsible for the fracture in the vicinity of melt pool (locally melted and rapidly solidified regions) boundaries.
Solar photovoltaic generation and energy storage play an increasingly important role in supplying the electricity needs of remote areas. However, private energy storage systems are a significant ...encumbrance to consumers in remote areas. Moreover, communal energy storage has enormous economic constraints owing to the distance from remote areas. In this study, we propose a new model for shared energy storage using the Neighbor scenario, where each consumer can share an energy storage system with the nearest consumer. To validate the model, we propose three scenarios: Individual, Neighbor, and Communal. The system was designed as a mixed-integer linear programming (MILP) model to analyze optimal operational schemes. The results show that using the Neighbor scenario can save operating costs and increase the storage utilization rate by 6.15% and 2.65%, respectively, relative to the other scenarios. Finally, a sensitivity analysis is performed to demonstrate optimal operation in terms of economic and emission parameters.
•Consumers in remote areas participate in shared energy storage.•MILP models are formulated to find optimal operations.•The benefits of neighbor storage compared to individual and communal storage.•Neighbor storage is evaluated using technological and social indicators.•Optimum operations are analyzed to provide insights for developing storage systems.
The power management system (PMS) for detached houses has been studied for many years; however, the PMS for apartment buildings (APBs) is not fully understood considering the structures of the APBs. ...Furthermore, electric vehicle (EV) batteries, photovoltaic (PV) generation, and battery energy storage system (BESS) can be used as distributed energy resources. Therefore, this study proposes an integrated PMS that optimizes the power schedules of individual residents, EV batteries, and common facilities (PV power generation and BESS) in APBs considering the time-of-use pricing policy. To develop the proposed system, a two-stage optimization was adopted using a genetic algorithm. For individual households, the first stage had three objectives: electricity cost, peak power, and user comfort. For the APB, the second stage had two objectives: total electricity cost and total peak power. To evaluate the performance of the proposed system, computational experiments were conducted in three cases: 1) unmanaged schedule, 2) conventional system, and 3) proposed system. For 50- and 100-unit APBs, the proposed PMS had lower total electricity costs (53119 JPY, 106150 JPY) and total peak power demands (184 kW, 366 kW) than the total electricity costs (54744 JPY, 109517 JPY) and total peak power demands (214 kW, 423 kW) of the conventional PMS. Based on a case study that used the proposed two-stage system with different weighting factors, the trade-off relationship among the five objectives of the proposed PMS was obtained. These findings suggest that the all-inclusive power scheduling of the APBs can be managed by dividing the comprehensive demand into individual household and common facility power demands, including cooperative systems. These results provide an important opportunity to advance the understanding of integrated PMS and cooperative systems for APBs. Further research is required to establish the dynamic relationships between households and APBs.
•Integrated power management system for an apartment building.•Vehicle-to-Home, PV generation and battery energy storage systems as DERs.•Two-stage system with multiple objectives considering household and building sides.
Internode line impedance values are essential information for achieving coordinated voltage regulation with distributed energy devices. However, in a low-voltage distribution system, these values are ...difficult to acquire, especially when the devices are installed in an ad hoc manner by individual users. This paper proposes a novel method for automated impedance estimation based on practically available parameters at the terminal nodes. The distributed energy devices measure and transmit the terminal parameters to a host device. Then, the host device estimates the line impedances based on its impedance model and the collected parameters. For practical implementation, the proposed method is built under several assumptions. For example, it is assumed that the phases of terminal voltages are not synchronized owing to communication latency. Instead, only the magnitude value is incorporated during the impedance estimation. The proposed method is verified via a simulation that assumes a realistic environment.
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Background: dCRT with 5-FU/MMC is a standard treatment for cStage II/III SCCA. S-1 is an oral fluoropyrimidine and has a greater effect on radiosensitivity. We conducted this trial ...of dCRT with S-1/MMC to determine the recommended dose (RD) of S-1 in dose-finding (phase I) part and to evaluate the efficacy and safety in confirmatory (phase II) part for cStage II/III SCCA. We reported the RD of S-1 and the 3-year survival at 2019 Gastrointestinal Cancers Symposium. We report the final data after 5-year follow-up. Methods: Eligibility criteria included histologically proven SCCA, cStage II/III (UICC 6th), PS 0-1, and age 20-80 years. dCRT consisted of MMC (10 mg/m
2
on days 1, 29) and S-1 (60 mg/m
2
/d in level 0 and 80 mg/m
2
/d in level 1 on days 1-14, 29-42) with concurrent radiotherapy of 59.4 Gy/33fr. The dose-finding part adopted the 3+3 cohort design. The primary endpoint of confirmatory part was 3-year event-free survival (EFS). The sample size was 65 in the confirmatory part, with one-sided alpha of 5% and power of 80%, threshold and expected 3-year EFS as 60% and 75%. Key secondary endpoints were overall survival (OS) and progression-free survival (PFS) and colostomy-free survival (CFS), and adverse events. Final analysis was planned after 5-year follow-up for all pts. Results: From Feb/2010 to Mar/2015, 69 pts (3 in level 0 and 66 7 in phase I and 59 in phase II in level 1) were enrolled. Pts characteristics for level 1 were as follows: M/F, 12/54; Age, median 64 (range 33-80); cStage II/IIIA/IIIB, 29/9/28. Three in level 1 were ineligible and 63 eligible assigned to level 1 were included in efficacy analysis. In the dose-finding part, RD of S-1 was determined as 80 mg/m
2
/d. The complete response rate was 81% (95% CI, 69.1-90.0%) on central review. With a median follow-up of 5.4 years, 3- and 5-year EFS was 65.0% (90% CI 54.1-73.9%) and 63.4% (95% CI 50.2-73.9%). 5-year OS, PFS, and CFS were 84.1% (95% CI 72.5-91.1%), 84.1% (95% CI 72.4-91.1%), and 73.0% (95% CI 60.2-82.3%), respectively. In a univariable analysis, male sex (p = 0.045) prognosticated for poor OS and cT3 or T4 (p = 0.001), male sex (p = 0.019) and, PS 1 (p = 0.048) prognosticated for poor CFS. Nine (14.3%) of 63 pts at a dose level 1 developed recurrence or disease progression. Locoregional recurrence only and distant metastasis were observed in 1 pts (1.6%) and 8 pts (12.7%) respectively. Among all treated 65 pts, only 5 pts (7.7%) showed grade 3 late toxicities including jejunum obstruction, jejunum ulcer, proctitis, lower gastrointestinal hemorrhage, anal pain, radiation dermatitis, and ureteral stenosis. No Grade 4 or 5 late toxicities were observed. Conclusions: dCRT with S-1/MMC showed acceptable toxicities and favorable 5-year survival and could be a possible treatment option for pts with locally advanced SCCA. Clinical trial information: jRCTs031180002.
Solar photovoltaic generation and energy storage are being used to power rural places. However, remote users are burdened by private energy storage devices. Remoteness limits the economic viability ...of cooperative energy storage. Our work proposes a shared energy storage model considering battery degradation. To test the model, we compared Individual, Neighbor, and Communal scenarios. The system was built as a mixed integer linear programming model to investigate optimal operating methods. Compared to the other situations, the Neighbor scenario saves operational expenses by 4.97%. Finally, the self-consumption rate shows optimal penetration of renewable energy parameters.
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