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In this study, changes in the microstructure, mechanical properties, and electrical conductivity of cast and extruded Al–Zn–Cu–Mg based alloys with the addition of Li (0, 0.5 and 1.0 wt.%) were investigated. The Al–Zn–Cu–Mg–xLi alloys were cast and homogenized at 570 °C for 4 hours. The billets were hot extruded into rod that were 12 mm in diameter with a reduction ratio of 38:1 at 550 °C. As the amount of Li added increased from 0 to 1.0 wt.%, the average grain size of the extruded Al alloy increased from 259.2 to 383.0 µm, and the high-angle grain boundaries (HGBs) fraction decreased from 64.0 to 52.1%. As the Li content increased from 0 to 1.0 wt.%, the elongation was not significantly different from 27.8 to 27.4% and the ultimate tensile strength (UTS) was improved from 146.7 to 160.6 MPa. As Li was added, spherical particles bonded to each other, forming an irregular particles. It is thought that these irregular particles contribute to the strength improvement.

In this study, microstructure and sintering behaviors of the gas-atomized Al-(25 or 30) Cr–xSi alloy (x = 5, 10 and 20 at.%) during spark plasma sintering (SPS) process were investigated. Gas-atomized alloy powders were manufactured using Ar gas atomizer process. These alloy powders were consolidated using SPS process at different temperature under pressure 60 MPa in vacuum. Microstructures of the gas-atomized powders and sintered alloys were analyzed using scanning electron microscopy (SEM) with energy–dispersive X-ray spectrometer (EDS), and transmission electron microscopy (TEM). Hardness of the SPS sintered alloys was measured using micro Vickers hardness tester. The Al–Cr–Si bulks with high Cr and Si content were produced successfully using SPS sintering process without crack and obtained fully dense specimens close to nearly 100% T. D. (Theoretical Density). The maximum values of the hardness were 834 Hv for the sintered specimen of the gas atomized Al–30Cr–20Si alloy. Enhancement of hardness value was resulted from the formation of the multi-intermetallic compound with the hard and thermally stable phases and fine microstructure by the addition of high Cr and Si.

In this study, changes in the microstructure, mechanical properties, and electrical conductivity of as-cast and as-extruded Al–B based alloys with the addition of Fe and rare earth (RE) were investigated. The melted aluminum alloy was maintained at 750 °C and then poured into a mould at 200 °C. Aluminum alloys were hot-extruded into a rod that was 12 mm in thickness with a reduction ratio of 39:1. The addition of Fe and RE resulted in the formation of Al11RE3 and Al3Fe intermetallic compounds and the area fraction of these inter-metallic compounds increased with increasing Fe and RE contents. As the amount of Fe and RE increased, the average grain size of the extruded Al alloy decreased to 798.6, 196.1, and 21.9 µm, and the high-angle grain boundaries fraction increased to 24.8, 27.9, and 60.7%. In the case of cast materials, low electrical conductivity was shown by porosity and fine casting defects. As the Fe and RE contents increased, the electrical conductivity of the extruded Al–B alloy decreased to 62.3, 59.6 and 55.0% International Annealed Copper Standard. As the Fe and RE content increased the ultimate tensile strength improved from 90.8 to 112.9 MPa which was attributed to the grain refinement and formation of Al11RE3 and Al3Fe intermetallic compounds by the addition of Fe and RE.

The effect of addition of Mischmetal (MM) on the microstructure, electrical and thermal conductivity, and mechanical properties of the as-extruded Al-MM based alloys were investigated. The studied AlxMM alloys (where x = 0.2, 0.5, 1.0, 1.5, 2.0 and 5.0 wt.%) were cast and homogenized at 550 °C for 4 h. The cast billets were extruded into 12 mm bars with an extrusion ratio of 39 at 550 °C. The addition of MM resulted in the formation of Al11(Ce, La)3 intermetallic compounds and the area fraction of these intermetallic compounds increased with an increase in the MM content. The Al11(Ce, La)3 phase, which was distributed in the as-cast alloys, was crushed into fine particles and arrayed along the extruded direction during the extrusion process. In particular, these intermetallic compounds in the extruded Al-5.0MM alloy were distributed with a wide-band structure due to the fragmentation of the eutectic phase with a lamellar structure. As the MM content increased from 1.0 wt.% to 5.0 wt.%, the average grain size decreased remarkably from 740 to 73 μm. This was due to formation of Al11(Ce, La)3 particles during the hot extrusion process, which promoted dynamic recrystallization and suppression of grain growth. The electrical and thermal conductivity of the extruded alloys containing up to 2.0 wt.% MM were around 60.5% IACS and 230 W/m · K, respectively. However, the electrical and thermal conductivity of the extruded alloy with 5.0 wt.% MM decreased to 55.4% IACS and 206 W/m · K, respectively. As the MM content increased from 1.0 wt.% to 5.0 wt.%, the ultimate tensile strength (UTS) was improved remarkably from 74 to 119 MPa which was attributed to the grain refinement and formation of Al11(Ce, La)3 intermetallic compounds by the addition of MM.

High conductivity Al alloys are widely used for electric materials, heat exchangers, and heat dissipation parts such as electric conductors, transmission lines, communication cables, automobile wires and so on. In this study, the effects of Ca and Mn addition on the microstructure and mechanical properties of Al–0.3Cu–0.2Fe–0.15Si–0.15Zn alloys were investigated. The melt was held at 800 °C for 20 minutes and poured into a mold. The cast Al alloy was hot extruded with a rod having a diameter of 12 mm and a reduction ratio of 38:1. Al–0.3Cu–0.2Fe–0.15Si–0.15Zn–0.9Mn–0.4Ca alloy consists of Al, Al–(Fe, Mn)–Si, Al–(Fe, Mn) and Al–(Ca) intermetallic compounds. The formation of the intermetallic compound and this phase was broken in to small particles during extrusion. As the Ca content increased from 0 to 0.4 wt.%, the electrical conductivity of the extruded Al–0.3Cu– 0.2Fe–0.15Si–0.15Zn alloys increased by 57.3, 57.9 and 59.0 %IACS (International annealed copper standard). Al–0.3Cu–0.2Fe–0.15Si–0.15Zn–0.9Mn alloy with element additions of Ca, ultimate tensile strength was decreased from 178.3 to 163.2 and 151.8 MPa. However, the elongation was improved to 18.6, 21.6 and 23.15%.

In this study, we investigate the microstructure and mechanical properties of as-extruded Al-1.0RE alloys. The molten Aluminum alloy was maintained at 800 °C and then poured into a mould at 200 °C. Aluminum alloys were hot-extruded into a rod measuring 12 mm thick with a reduction ratio of 38:1. The microstructure and electric conductivity properties of as-extruded Al-1.0RE alloy under different annealing processes were investigated and compared. After extrusion, the intermetallic compound having a needle shape in the cast state was finely decomposed based on the direction of extrusion. Significant changes in the microstructure were detected after annealing at 500 °C with fragmentation and sphering of eutectic particles. The annealing temperature of Al-1.0RE alloy increased proportionally to the electrical conductivity. The formation of Al-RE intermetallic compounds increases the electrical conductivity and improves the mechanical properties of the alloy through precipitation hardening.

Microstructure and texture of P-type 75%Sb₂Te₃-25%Bi₂Te₃ alloy fabricated by using gas-atomization and extrusion processes was investigated. The microstructure of the gas-atomized powders exhibited fine grains with needle shape. After hot extrusion, grain size was characterized by fine and equiaxed grains due to dynamic recrystallization by severe deformation. (0001) basal planes of the extruded specimens were preferentially orientated parallel to extrusion direction. As extrusion temperature, fraction of the basal planes was increased.

In this work, Al-0.15Si-0.2Fe-0.3Cu-0.9Mn alloys with different Zn addition (0, 0.15 and 0.3 wt%) were melted and extruded at 200 °C. The effect of Zn on the microstructure, texture evolution and mechanical properties of Al-0.15Si-0.2Fe-0.3Cu-0.9Mn alloys was investigated using scanning electron microscope (SEM), equipped with energy-dispersive X-ray spectrometry (EDS) and electron backscatter diffraction (EBSD) and in the present study. In order to evaluate the mechanical properties, we implemented the tensile tests by a universal material test machine. Al-0.15Si-0.2Fe- 0.3Cu-0.9Mn-xZ resulted in the formation of Al-(Fe, Mn)-Si and Al-(Fe, Mn) intermetallic compounds. The formation of the intermetallic compound and this phase was broken in to small particles during extrusion. The ultimate strength and elongation of the as-extruded Al-0.15Si-0.2Fe-0.3Cu- 0.9Mn alloy were 96.51 MPa and 34.01%, while those of the Al-0.15Si-0.2Fe-0.3Cu-0.9Mn-0.3Zn alloy were 99.08 MPa and 36.21%, respectively. Al-0.15Si-0.2Fe-0.3Cu-0.9Mn alloys with Zn addition resulted in improving the strength with no reduction in elongation.

In this study, microstructure and sintering behaviors of the gas-atomized Al-(25 or 30) Cr-xSi alloy (

Microstructure and properties of Al–2 wt.%Zn–1 wt.%Cu–xMg (x = 0.1, 0.3, 0.5, 0.7 wt.%) alloy extrusion materials were investigated. The lattice constants for the (311) plane increased to 4.046858, 4.048483, 4.050114 and 4.051149 Å with the addition of 0.1, 0.3, 0.5, and 0.7 wt.% of elemental Mg. The average grain size of the as-extruded Al alloys was found to be 328.7, 297.7, 187.0 and 159.3 μm for the alloys with 0.1, 0.3, 0.5, and 0.7 wt.% Mg content, respectively. The changes in the electrical conductivity by the addition of elemental Mg in Al–2 wt.%Zn–1 wt.%Cu alloy was determined, and it was found that for the addition of 0.1, 0.3, 0.5, and 0.7 wt.% Mg, the conductivity decreased to 51.62, 49.74, 48.26 and 46.80 %IACS. The ultimate tensile strength of Al–2 wt.%Zn–1 wt.%Cu–0.7 wt.%Mg alloy extrusion was increased to 203.55 MPa. Thus, this study demonstrated the correlation between the electrical conductivity and strength for the Al–2 wt.%Zn–1 wt.%Cu–xMg alloys.

The effect of addition of Mischmetal (MM) on the microstructure, electrical and thermal conductivity, and mechanical properties of the as-extruded Al-MM based alloys were investigated. The studied Al

Fe is considered as one of the most harmful trace elements among impurities in aluminum and its alloys due to its influence of the mechanical properties especially in elongation. It is therefore essential that the Fe content is controlled to improve quality and the toughness of aluminum alloy castings. Since demand for high strength aluminum alloy casting was significantly increased in electro materials and devices, automotive and airplane industries, it is necessary to characterize the effect of Fe and set the tolerable amount of Fe content in aluminum alloys. Al6061 alloys were prepared with compositions of 0.36, 0.45, 0.58, 0.65, 0.75, 0.81 and 0.91 wt.% Fe. Solidification characteristics were analyzed by CALPHAD (Pandat software) method. Mechanical properties such as hardness, tensile strength, elongation and fatigue strength were evaluated and compared with different Fe contents. Al13Fe4 phase increased with increasing as Fe content, however, other phases, α-AlFeSi and Mg2Si, showder a slight decrease. The higher the Fe content, the lower the electrical conductivity of the alloy due to the severe distortion of the Al matrix. As Fe content was more than specification of Al6061 alloy, 0.7 wt.%, the mechanical properties, especially, hardness and elongation were greatly influenced. The hardness is attributed to the poor densification and angular-shaped Al13Fe4 phases unevenly distributed in the α-Al matrix.

In order to investigate the microstructure and mechanical properties on Al–25Cr–5Si (at%) alloy, a mixed powder with pure elements and an alloy powder using a gas atomization process were used. Fine and high purity Al–25Cr–5Si (at%) alloy powder was successfully prepared by gas atomization and densified using a spark plasma sintering (SPS) process. The overall powder size distribution of the mixed Al, Cr, and Si elemental powders was in the range of 10–15 μm. The atomized Al–Cr–Si alloy powder was fine and spherical in morphology and difficult to be formed by intermetallic formation. Densification was clearly confirmed at 1000 °C, with almost isolated pores formed, by clear removal of pores between particles, deformation of particles, an increase in the number of contacts, and a change in size between particles. As a result of XRD analysis of the sintered compacts, single phase was observed using the mixed powder, but the compact using gas atomization remained the alloy phase even at the process temperature. The Vickers hardness of the compacts by mixed powder was observed at 59.70 Hv and the compact using gas atomized powders on the temperature 1000 °C of the Vickers hardness increased to 702.6 Hv. The compressive yield strength of the compact with mixed powder was 195.24 MPa and the compressive strength of the compact with gas atomized powder increased to 802.07 MPa. It is considered not to be decomposed by the AlCrSi, Al13Cr4Si4 and Al8Cr5 phases sintering process, resulting from the improvement of mechanical properties. We have obtained a fine and high purity Al–25Cr–5Si (at%) alloy powder, which has been successfully manufactured by gas atomization. The atomized Al–Cr–Si alloy powder was fine and spherical in morphology and difficult to be formed by intermetallic formation. Alloy powders have been densified using a pulsed current-activated sintering (PCAS) process. The Vickers hardness of the compacts by mixed powder was observed at 59.70 Hv and the compact using gas atomized powders on the temperature 1000 ℃ of the Vickers hardness increased to 702.6 Hv. The compressive yield strength of the compact with mixed powder was 195.24 MPa and the compressive strength of the compact with gas atomized powder increased to 802.07 MPa.

We investigated the effects of Al-5.0wt%Ti-1.0wt%B addition on the microstructure and mechanical properties of the as-extruded Al-0.15wt%Si-0.2wt%Fe-0.3wt%Cu-0.15wt%Zn-0.9wt%Mn based alloys. The Aluminum alloy melt was held at 800 °C and then poured into a mould at 200 °C. Aluminum alloys were hot-extruded into a rod that was 12 mm in thickness with a reduction ratio of 38:1. AlTiB addition to Al-0.15Si-0.2Fe-0.3Cu-0.15Zn-0.9Mn based alloys resulted in the formation of Al3Ti and TiB2 intermetallic compounds and grain refinement. With increasing of addition AlTiB, ultimate tensile strength increased from 93.38 to 99.02 to 100.01 MPa. The tensile strength of the as-extruded alloys was improved due to the formation of intermetallic compounds and grain refinement.

Accumulative roll-bonding (ARB) is the most appropriate process for sheet-shaped materials because it can be carried out readily by utilizing the conventional rolling apparatus. In this study, a nanostructured AA1050/AA5052 Al alloy sheet was successfully fabricated by four-layer stack ARB process. The ARB of AA1050 and AA5052 alloy sheets was performed up to 6 cycles without a lubricant at ambient temperature. The sample fabricated by the ARB was a multi-layer aluminum alloy sheet in which AA1050 and AA5052 layers are alternately stacked. The layer thickness of the each alloy became thinner and elongated to the rolling direction with the number of ARB cycles. The grain size decreased with increasing of the number of ARB cycles, after 6 cycles it became about 180 nm in thickness. The fraction of high angle grain boundaries increased with the number of ARB cycles. The tensile strength also increased with the ARB, it reached 305 MPa which is about 2.1 times that of the as-received AA1050. The mechanical properties of a multi-layer AA1050/AA5052 alloy fabricated by the ARB were compared to those of the other materials.

Niobium-titanium alloy is attractive materials for industrials as a superconducting magnets to high critical magnetic field and supercurrent density at -283 °C. The Nb-Ti alloy has been shown in earlier work to exhibit Van Gosh Sky microstructures. They may also be accentuated by plastic deformation due to work and temperature exposure during deformation. In order to miniaturize the magnet generating the same magnetic field, it is necessary to increase the critical current density of the superconducting wire. When fabricating superconducting wires, it is important to increase critical current density by optimizing processing and annealing conditions. When the α-phase of the Ti rich phase is uniformly precipitated by the heat treatment, the non-superconducting α-phase is dispersed in the superconducting Nb-Ti matrix. It becomes a pinning point that serves to fix the magnetic flux, which improves the critical current density. Also, if the shape of the precipitate is changed by machining, the superconducting and non-superconducting characteristics are further improved. In the present study, we studied the fraction of α-Ti phase of strain amount through groove rolling and heat treatment. The specimens were processed by groove rolling at room temperature and strain of 2.0, 3.16, 4.28 and 5.57. A microstructural analysis of the Nb-Ti alloys was performed by field emission scanning electron microscopy (FESEM).

Objective It is well known that cancer patients' perception of social support is associated with their depressive symptoms and health-related quality of life. However, there have been little studies that compared the variates of cancer patients with the general population. We sought to compare differences in the level of perceived social support and the impact of perceived social support on depressive symptoms and health-related quality of life between cancer survivors and the general population. Methods Data were collected from 1818 cancer patients treated at the National Cancer Center and regional cancer centers in South Korea. The control group of the general population was composed of 2000 individuals without cancer from community. Results Cancer patients reported significantly higher level of perceived social support than the general population, while they reported lower health-related quality of life and were more susceptible to depression. The positive associations of higher perceived social support with lower depressive symptoms, as well as with higher health-related quality of life, were stronger among cancer patients than among the general population. Conclusions The interaction effect suggests that the impact of social support would be stronger among cancer patients than the general public. Thus, it would be beneficial to pay attention to providing social support to cancer patients, particularly to those who are more vulnerable. Furthermore, investigation of the most effective and efficient methods to deliver social support interventions would be worthwhile.

The hot deformation characteristics of an UNS No. S32205 grade duplex stainless steel with nitrogen content of 0.17 ms% was studied over the ranges of temperature from 800 to 1200 °C and strain rates from 0.001 to 1.0 s−1 at the total strain of 0.5 by the hot compression test to draw the processing map. The obtained map was discussed in combinations of microstructural observations and TEM analysis. The optimum hot working region is the temperatures from 950 to 1200 °C regardless of the strain rates without cracks and sigma precipitates.

In this research, effects of Zn and Cu content on microstructure, mechanical properties, electric and thermal conductivity of the as-extruded Al

Thermal properties and microstructure of Al-4 wt.% Zn-2 wt.% Cu–x (x = 2 wt%. Mg, 2 wt%. Sn, 0.7 wt.% Mg-0.7 wt.% Sn-0.7 wt.% Ca) alloys on cast and extrusion have been investigated with extrusion temperature of 400 °C. Al-4 wt.% Zn-2 wt.% Cu alloy was composed of Al and Al2Cu phases. By adding Mg contents, Al2Mg3Zn3 phase was increased and Al2Cu phase was decreased respectively. During hot extrusion, elongated in the extrusion direction because of severe deformation. The thermal conductivity with temperature and composition of as-extruded Al-4 wt.% Zn-2 wt.% Cu–x alloys decreases with adding 2 wt.% Mg, 2 wt.% Sn contents from 190.925 and 196.451 W/mK but thermal properties of addition of 0.7 wt.% Mg-0.7 wt.% Sn-0.7 wt.% Ca element slightly reduced from 222.32 to 180.775 W/mK. The ultimate tensile strength (UTS) for Al-4 wt.% Zn- 2 wt.% Cu alloy was 121.67 MPa. By adding 2 wt.% Mg contents, tensile strength was dramatically increased with 350.5 MPa.

Benefits of the Integrated Demand Management (IDM) concept were assessed utilizing a newly developed automated simulation capability called ‘Traffic Management Initiative Automated Simulation (TMIAutoSim).’ The IDM concept focuses on improving traffic flow management (TFM) by coordinating the FAA’s strategic Traffic Flow Management System (TFMS) with its more tactical Time-Based Flow Management (TBFM) system. The IDM concept leverages a new TFMS capability called Collaborative Trajectory Options Program (CTOP) to strategically pre-condition traffic demand flowing into a TBFM-managed arrival environment, where TBFM is responsible for tactically managing traffic by generating precise arrival schedules. The IDM concept was developed over a multi-year effort, focusing on solving New York metroplex airport arrival problems. TMIAutoSim closely mimics NASA’s high-fidelity simulation capabilities while enabling more data to be collected at higher speed. Using this new capability, the IDM concept was evaluated using realistic traffic across various weather scenarios. Six representative weather days were selected after clustering three months of historical data. For those selected six days, Newark Liberty International Airport (EWR) and LaGuardia Airport (LGA) arrival traffic scenarios were developed. For each selected day, the historical data were analyzed to accurately simulate actual operations and the weather impact of the day. The current day operations and the IDM concept operations were simulated for the same weather scenarios and the results were compared. The selected six days were categorized into two groups: ‘clear weather’ for days without Ground Delay Programs (GDP) and ‘convective weather’ for days with GDP and significant weather around New York metroplex airports. For the clear weather scenarios, IDM operations reduced last minute, unanticipated departure delays for short-haul flights within TBFM control boundaries with minimal to no impact on throughput and total delay. For the convective weather scenarios, IDM significantly reduced delays and increased throughput to the destination airports.

Aluminum and its alloys are used in a wide range of industrial applications from low density, high strength and a variety of structural materials. In this study, the effects of Ca addition on the microstructure and mechanical properties of Al-1wt.%RE alloys were investigated. The melt was held at 800 °C for 20 minutes and poured into a mold. The cast Al alloy was hot extruded with a rod having a diameter of 12 mm and a reduction ratio of 38:1. Al-1wt.%RE alloy consists of Al, Al11RE₃ phase. The Al₂Ca phase is increased by increasing the Ca content to 0.2 to 0.4 wt.%. As the Ca content increased from 0 to 0.4 wt.%, the average grain size of the extruded Al alloy decreased by 739.8, 400.8 and 155.0 μm. The tensile strengths were increased to 74.25, 76.53, and 79.52 MPa. The electrical conductivity of Al-RE alloy with Ca addition decreased to 60.32, 58.15 and 57.89% IACS.

Microstructure and texture of

The purpose of this study was to compare flow constrained area (FCA) capacity setting methods for Collaborative Trajectory Options Program (CTOP) as they pertain to the Integrated Demand Management (IDM) concept. IDM uses flow balancing to manage air traffic across multiple FCAs with a common downstream constraint, as well as constraints at the respective FCA locations. FCA capacity rates can be set manually, but generating capacities for multiple, interdependent FCAs could potentially over-burden a user. A new enhancement to CTOP called the FCA Balance Algorithm (FBA) was developed at NASA Ames Research Center to improve the process of allocating capacity across multiple flow constrained segments in the airspace. The FBA evaluates the predicted demand and capacity across multiple FCAs and dynamically generates capacity settings for the FCAs that best meet capacity limits for all identified constraints. In a human-in-the-loop simulation study, both manual and automated capacity setting methods were evaluated in terms of their overall feasibility using measures of system performance, human performance, and qualitative feedback. Subject matter experts were asked to use three different methods to allocate capacity to three FCAs, either (1) by manually setting capacity for every 60-minute time window, (2) by manually setting capacity for every 15-minute time window, or (3) by using the FBA capability to automatically generate capacity settings. Results showed no significant differences in terms of overall system performance, indicated by similar ground delay and airport throughput numbers between methods. However, differences in individual strategies afforded by the manual methods allowed some participants to achieve system-wide delay that was much lower than the average. The FBA was the fastest method of capacity setting, and it received the lowest subjective rating scores on physical task load, mental task load, task difficulty and task complexity out of the three methods. Finally, participants explained through qualitative feedback that there were many benefits to using the FBA, such as ease of use, accuracy, and low risk of human input error. Participants did not experience the same limitations with the FBA that they did with the manual methods, such as reduced accuracy in the 60-minute manual condition, or high complexity in the 15-minute/manual condition. These results suggest that the FBA automation enhancement to CTOP maintains system performance while improving human performance. Therefore, the FBA could be introduced as a way to mitigate operator workload while planning a CTOP.

This paper presents the methodology and results of a Human-In-The-Loop (HITL) simulation study conducted in the Airspace Operations Laboratory at NASA Ames Research Center. This study is a part of NASA's ongoing research into developing an Integrated Demand Management (IDM) concept, whose aim is to improve traffic flow management (TFM) by coordinating the FAA's strategic Traffic Flow Management System (TFMS) with its more tactical Time-Based Flow Management (TBFM) system. The purpose of TFM is to regulate air traffic demand so that it is delivered efficiently through constrained airspace resources without exceeding their capacity limits. The IDM concept leverages a new TFMS capability called the Collaborative Trajectory Options Program (CTOP) to strategically pre-condition traffic demand flowing into a TBFM-managed arrival environment, where TBFM is responsible for managing traffic tactically by generating precise arrival schedules. Unlike other TFM tools, CTOP gives flight operators the option of submitting a set of user-preferred alternative trajectories for each flight. CTOP can then use these trajectory option sets (or TOSs) to find user-preferred alternative routes to reduce demand on an overloaded resource. CTOP's effectiveness in redistributing demand is limited, however, by the availability of flights with alternative routes. The research presented in this paper focuses on evaluating the impact on TFM operations by varying the percentage of flights that submit a multiple-option TOS ('TOS participation levels'). Results show the impact on overall system performance and on the rerouted flights themselves. The simulation used a Newark (EWR) airport arrival scenario, with en route weather affecting traffic inbound from the west. Participants were asked to control each of the three arrival flows (north, west, and south) to meet their individual capacity constraints while simultaneously ensuring efficient utilization of the capacity at the destination airport. A large, permeable convective weather cell located southeast of Chicago severely reduced the capacity of the west flow. The study evaluated the impact of five different TOS participation levels on CTOP's ability to re-allocate traffic from the west and improve TFM performance in terms of delay assignment and traffic delivery rate to the airport. Overall, the results showed that increasing TOS submissions allowed the overall system delays to be reduced and fairly distributed among the three arrival flows, at the same time achieving the airport throughput rate. Moreover, it was found that aircraft who submitted a TOS saw a greater reduction in delay, even when they were assigned longer routes. This was particularly true when fewer aircraft submitted a TOS. The results confirm that the CTOP operations with higher TOS participation levels helped utilize the overall National Airspace System (NAS) resources as well as benefited the users who participated.

The microstructure and mechanical properties of as-extruded Al-0.1 wt%Si-0.2 wt%Fe- 0.4 wt%Cu-0.04 wt%Zr-xMn-xAlTiB (x = 1.0 wt%) alloys under various annealing processes were investigated and compared. After the as-cast billets were kept at 400 °C for 1 hr, hot extrusion was carried out with a reduction ratio of 38:1. In the case of the as-extruded Al-Si-Fe-Cu-Zr alloy at annealed at 620 °C, large equiaxed grain was observed. When the Mn content is 1.0 wt%, the phase exhibits a skeleton morphology, the phase formation in which Mn participated. Also, the volume fraction of the intermetallic compounds increased with Mn and AlTiB addition. For the Al-0.1Si-0.2Fe-0.4Cu-0.04Zr alloy with Mn and AlTiB addition from 1.0 wt%, the ultimate tensile strength increased from 100.47 to 119.41 to 110.49 MPa. The tensile strength of the as-extruded alloys improved with the addition of Mn and AlTiB due to the formation of Mn and AlTiB-containing intermetallic compounds.

Magnesium and its alloys are potential candidates for many automotive and aerospace applications due to their low density and high specific strength. However, the use of magnesium as wrought products is limited because of its poor workability at ambient temperatures. Mg-Li alloys containing 5-11 wt.% Li exhibit a two-phase structure consisting of a α (hcp) Mg-rich phase and a β (bcc) Li-rich phase. Mg-Li alloys with Li content greater than 11 wt.% exhibit a single-phase structure consisting of only the β phase. In the present study, we studied the effects of Y addition on the microstructure and mechanical properties of Mg-11Li-6Zn-0.6Zr-0.4Ag-0.2Ca based alloys. The melt was maintained at 720 °C for 20 min and poured into a mold. Then, the as-cast Mg alloys were homogenized at 350 °C for 4 h and were hot-extruded onto a 4-mm-thick plate with a reduction ratio of 14:1. The as-cast Mg-11Li-6Zn-0.6Zr-0.4Ag-0.2Ca-xY (x 0, 1, 3, and 5 wt.%) alloys were composed of α-Mg, β-Li, γ-Mg2Zn3Li, I-Mg3YZn6, W-Mg3Y2Zn3, and X-Mg12YZn phases. By increasing the Y content from 0 to 5 wt.%, the composition of the W-Mg3Y2Zn3 phase increased. With increasing Y content, from 0 to 1, 3, and 5 wt.%, the average grain size and ultimate tensile of the as-extruded Mg alloys decreased slightly, from 8.4, to 3.62, 3.56, and 3.44 μm and from 228.92 to 215.57, 187.47, and 161.04 MPa, respectively, at room temperature.

In this study, the effects of heat-treatment conditions on the densification, microstructure, and magnetic properties of Fe powder were investigated. The oxygen content of the Fe powders heat-treated in Ar and Ar-H2 atmosphere was much lower than that of the Fe powder heat-treated in air atmosphere. The density of the compacts of the Fe powder heat-treated in Ar and Ar + H2 atmosphere was higher than that of the compacts of Fe powders heat-treated in air. Oxygen content in the heat-treatment conditions played a significant role in the improvement of the densification and magnetic properties.

Air traffic management in the New York (NY) metropolitan area presents significant challenges such as excess demand, chronic delays, and inefficient routes. At NASA, a new research effort has been ...

Microstructure and thermal properties of Mg–(3 mass% or 5 mass%) Sn–2 mass% Ca alloys as casts and extrusions have been investigated with different ram speeds and extrusion temperatures. Mg–(3 mass% or 5 mass%) Sn–2 mass% Ca alloys are composed of $$\upalpha $$ -Mg, MgSnCa, and $$\hbox {Mg}_{2}\hbox {Ca}$$ phases. By adding Sn content from 3 mass% to 5 mass%, the MgSnCa phase is increased and the $$\hbox {Mg}_{2}\hbox {Ca}$$ phase is decreased. During hot extrusion, the average grain sizes are increased with increasing ram speed and temperature. The ultimate tensile strength (UTS) and elongation for the Mg–5Sn–2Ca alloy at $$2.3\, \hbox {mm}{\cdot }\hbox {s}^{-1}$$ are 227.73 MPa and 18.43 %, respectively. With increasing extrusion ram speed, the UTS and elongation for the Mg–5Sn–2Ca alloy are remarkably decreased to 215.95 MPa, 206.33 MPa, and 14.74 %, 6.88 %, respectively. The thermal conductivity for the Mg–3Sn–2Ca alloy is dramatically improved, compared to commercialized Mg alloys such as AZ31 and AZ91 due to formation of MgSnCa and $$\hbox {Mg}_{2}\hbox {Ca}$$ phases.