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During aircraft, ship, and automobile manufacturing, lap structures are frequently produced among Al alloy skins, wall panels, and stiffeners. The occurrence of welding defects severely decreases mechanical properties during friction stir lap welding (FSLW). This study focuses on investigating the effects of rotation rate, multipass welding, and cooling methods on lap defect formation, microstructural evolution, and mechanical properties. Hook defects were eliminated by decreasing welding speed, applying two-pass FLSW with a small welding tool, and introducing additional water cooling, thus leading to a remarkable increase in effective sheet thickness and lap width. This above strategy yielded defect-free joints with an ultrafine-grained microstructure and increased tensile shear force from 298 to 551 N/mm. The fracture behavior of FSLW joints was systematically studied, and a fracture factor of lap joints was proposed to predict their fracture mode. By reducing the rotation rate, using two-pass welding, and employing additional water cooling strategies, an enlarged, strengthened, and defect-free lap zone with refined ultrafine grains was achieved with a quality comparable to that of lap welds based on 7xxx Al alloys. Importantly, this study provides a valuable FSLW method for eliminating hook defects and improving joint performance.

Although real options theory normatively suggests that managers should associate real options with project value, little field research has been conducted to test whether they suffer from systematic biases in doing so. We draw on the notion of bounded rationality in managerial decision making to explore this understudied phenomenon. Using data collected from managers in 88 firms, we show that managers exhibit what we label the bounded rationality bias in their assessments: They associate real options with value only when a project's easily quantifiable benefits are low, but fail to do so when they are high. The study also contributes the first set of empirical measures for all six types of real options. The study contributes to managerial practice by identifying the conditions under which managers must be vigilant about inadvertently neglecting real options and by providing a simple approach for assessing real options in technology development projects.

Considering the requirements pertaining to the trafficability of off-road vehicles on rough roads, and since their roll stability deteriorates rapidly when turning violently or passing slant roads due to a high center of gravity (CG), an efficient anti-slip control (ASC) method with superior instantaneity and robustness, in conjunction with a rollover prevention algorithm, was proposed in this study. A nonlinear 14 DOF vehicle model was initially constructed in order to explain the dynamic coupling mechanism among the lateral motion, yaw motion and roll motion of vehicles. To acquire physical state changes and friction forces of the tires in real time, corrected LuGre tire models were utilized with the aid of resolvers and inertial sensors, and an adaptive sliding mode controller (ASMC) was designed to suppress each wheel’s slip ratio. In addition, a model predictive controller (MPC) was established to forecast rollover risk and roll moment in reaction to the change in the lateral forces as well as the different ground heights of the opposite wheels. During experimentation, the mutations of tire adhesion capacity were quickly discerned and the wheel-hub drive motors (WHDM) and ASC maintained the drive efficiency under different adhesion conditions. Finally, a hardware-in-the-loop (HIL) platform made up of the vehicle dynamic model in the dSPACE software, semi-active suspension (SAS), a vehicle control unit (VCU) and driver simulator was constructed, where the prediction and moving optimization of MPC was found to enhance roll stability effectively by reducing the length of roll arm when necessary.

Al-5Mg-0.8Mn alloys (AA5083) with various iron and silicon contents were cast under near-rapid cooling and rolled into sheets. The aim was to study the feasibility of minimizing the deteriorating level of the harmful Fe-rich phases on the mechanical properties through refining the intermetallics by significantly increasing the casting rate. The results showed that the size and density of the intermetallic particles that remained in the hot bands and the cold rolled sheets increased as the contents of iron and silicon in the alloys were increased. However, the increment of the particle sizes was limited due to the significant refinement of the intermetallics formed during casting under near-rapid cooling. The mechanical properties of the alloys reduced as the contents of iron and silicon in the alloys increased. However, the decrement of tensile strengths and ductility was quite small. Therefore, higher contents of iron and silicon could be used in the Al-5Mg-0.8Mn alloy (AA5083 alloy) when the material is cast under near-rapid cooling, such as in the continuous strip casting process.

The development of microwave absorbing materials with attributes such as low weight, broad absorption bandwidth, and superior thermal insulation performance is still challenging. In this study, Fe3O4 nanoparticles were anchored on Ti3C2Tx MXene/RGO nanosheets by one-step hydrothermal gelation method to prepare Fe3O4/Ti3C2Tx MXene/RGO (FeMR) hybrid aerogels. Perfect impedance matching and electromagnetic coupling effect were achieved by adjusting the composition ratio of FeMR aerogels, so exceptionally outstanding microwave absorption performance was obtained. FeMR aerogel at 2.90 mm thickness, effective absorption bandwidth (EAB) up to 8.10 GHz. Simultaneously, FeMR aerogels have has good thermal insulation performance. After heating at 300°C for 60 min, the aerogel can still isolate the thermal radiation of about 155 °C. This work demonstrates a simple method for preparing lightweight, broadband electromagnetic wave absorption and heat insulation three-dimensional MXene-based aerogels, which provides inspiration for the structural design and potential applications of EWA materials.

The development of microwave absorbing materials with attributes such as low weight, broad absorption bandwidth, and superior thermal insulation performance is still challenging. In this study, Fe 3 O 4 nanoparticles were anchored on Ti 3 C 2 T x MXene/RGO nanosheets by one-step hydrothermal gelation method to prepare Fe 3 O 4 /Ti 3 C 2 T x MXene/RGO (FeMR) hybrid aerogels. Perfect impedance matching and electromagnetic coupling effect were achieved by adjusting the composition ratio of FeMR aerogels, so exceptionally outstanding microwave absorption performance was obtained. FeMR aerogel at 2.90 mm thickness, effective absorption bandwidth (EAB) up to 8.10 GHz. Simultaneously, FeMR aerogels have has good thermal insulation performance. After heating at 300°C for 60 min, the aerogel can still isolate the thermal radiation of about 155 °C. This work demonstrates a simple method for preparing lightweight, broadband electromagnetic wave absorption and heat insulation three-dimensional MXene-based aerogels, which provides inspiration for the structural design and potential applications of EWA materials.

At present, the preparation of absorbing materials that combine light weight, ultra-wideband absorption and good thermal insulation performance is still an insurmountable gap. Here, we constructed a three-dimensional porous structure in the hope of obtaining excellent microwave absorption and heat insulation properties. In this paper, a unique three-dimensional porous SiCNWs/Ti 3 C 2 T x /RGO (STR) aerogel was prepared by hydrothermal treatment. When the mass ratio of SiCNWs, Ti 3 C 2 T x and GO is 2:1:1, the effective absorption bandwidth of STR aerogel reaches 8.10 GHz (9.90–18.00 GHz). Moreover, the porous structure can effectively reduce the heat radiation transfer. After heating at 300 ℃ for 1 h, STR aerogel can effectively isolate the temperature of about 160 ℃, which proves that STR has good thermal insulation performance. In addition, the formation mechanism of the STR aerogels and the mechanism of thermal insulation and electromagnetic wave absorption of aerogels are also discussed, which will contribute to the development and application of new lightweight stealth material.

Lightweight flexible composite films are widely used in the field of smart and wearable devices due to efficient electromagnetic interference (EMI) shielding effectiveness in the wide frequency domain and excellent mechanical properties. Herein, the CNTs@MXene composite films with excellent mechanical properties and EMI effectiveness were prepared by electrophoretic deposition method on carbon nanotubes (CNTs) substrate. By optimizing the experimental parameters, the optimal deposition time was determined to be 15 min. Meanwhile, the mechanical properties of the 40 μm composite films were the best and the tensile strength reached about 29.2 MPa. Moreover, the composite films with the same thickness showed excellent electromagnetic shielding effects of 69.02 dB and 77.32 dB in X-band and P-band, respectively. The CNTs@MXene composite films showed excellent EMI shielding effectiveness and mechanical properties. Therefore, the composite films showed great advantages and potentials in the application of smart and wearable devices. Graphical abstract

Mn was an important alloying element used in Al–Mg–Mn alloys. However, it had to be limited to a low level (<1.0 wt %) to avoid the formation of coarse intermetallics. In order to take full advantage of the benefits of Mn, research was carried out to investigate the possibility of increasing the content of Mn by studying the effect of cooling rate on the formation of Fe- and Mn-rich intermetallics at different content levels of Mn and Fe. The results indicated that in Al–5Mg–Mn alloy with low Fe content (<0.1 wt %), intermetallic Al6(Fe,Mn) was small in size and amount. With increasing Mn content, intermetallic Al6(Fe,Mn) increased, but in limited amount. In high-Fe-containing Al–5Mg–Mn alloys (0.5 wt % Fe), intermetallic Al6(Fe,Mn) became the dominant phase, even in the alloy with low Mn content (0.39 wt %). Cooling rate played a critical role in the refinement of the intermetallics. Under near-rapid cooling, intermetallic Al6(Fe,Mn) was extremely refined. Even in the high Mn and/or high-Fe-containing alloys, it still demonstrated fine Chinese script structures. However, once the alloy composition passed beyond the eutectic point, the primary intermetallic Al6(Fe,Mn) phase displayed extremely coarse platelet-like morphology. Increasing the content of Fe caused intermetallic Al6(Fe,Mn) to become the primary phase at a lower Mn content.

Numerous studies have demonstrated that in residential areas of Western cities, both luxury and legacy effects significantly shape tree species diversity dynamics. However, the specific mechanisms driving these diversity patterns in China, where urbanization has progressed at an unprecedented pace, remain poorly understood. In this study we selected 20 residential settlements and 7 key socio-economic properties to investigate the change trend of tree diversity (2006–2021) and its socio-economic driving factors in Beijing. Our results demonstrate significant increases in total, native, and exotic tree species richness between 2006 and 2021 (p < 0.05), with average increases of 36%, 26%, and 55%, respectively. Total and exotic tree Shannon-Wiener indices, as well as exotic tree Simpson’s index, were also significantly higher in 2021 (p < 0.05). Housing prices was the dominant driver shaping total and exotic tree diversity, showing significant positive correlations with both metrics. In contrast, native tree diversity exhibited a strong positive association with neighborhood age. Our findings highlight two dominant mechanisms: legacy effect, where older neighborhoods preserve native diversity through historical planting practices, and luxury effect, where affluent communities drive exotic species proliferation through ornamental landscaping initiatives. These findings elucidate the dual dynamics of legacy conservation and luxury-driven cultivation in urban forest development, revealing how historical contingencies and contemporary socioeconomic forces jointly shape tree diversity patterns in urban ecosystems.