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The bed structure of high-grade large-scale CNC machine tools is crucial for maintaining their long-term service accuracy. This study focused on the key casting process of large nodular cast iron beds. AnyCasting software was employed to simulate and analyze the casting scheme, and then the mold filling and solidification processes were proposed based on the simulation results. The proposed casting scheme indicates that the designed gating system exhibited excellent filling capability. The dual sprue ceramic pipe bottom pouring technique, in conjunction with the chills, not only improved casting efficiency but also met the requirements of sequential solidification design. The castings possessed a dense microstructure characterized by uniform and stable phase composition, primarily comprising lamellar pearlite, with ≤0.5% of phosphorus eutectic and cementite. Furthermore, the microstructure of these materials displayed favorable graphite morphology with a spheroidization rate exceeding 85% and spheroidization grade of 2–3. This study has important academic and application value for the casting process of producing low-stress, high-grade CNC machine tool bed cast iron materials.

Nonlinear metasurfaces with high conversion efficiencies have been vastly investigated. However, strong dynamic tunability of such devices is limited in conventional passive plasmonic and dielectric material platforms. Germanium antimony telluride (GST) is a promising phase-change chalcogenide for the reconfiguration of metamaterials due to strong nonvolatile changes of the real and imaginary parts of the refraction index through amorphous-crystalline phase change. The orderly structured GST has an even higher potential in tunable second-harmonic generation (SHG) with a non-centrosymmetric crystal structure at the crystalline phase, while the amorphous phase of GST does not exhibit bulk second-order nonlinearity. Here, we experimentally demonstrate SHG switches by actively controlling the crystalline phase of GST for a GST-based hybrid metasurface featuring a gap-surface plasmon resonance, and a quarter-wave asymmetric Fabry–Perot (F–P) cavity incorporating GST. We obtain SHG switches with modulation depths as high as ∼ 20 dB for the wavelengths at the on-state resonance. We also demonstrate the feasibility of multi-level SHG modulation by leveraging three controlled GST phases, i.e., amorphous, semi-crystalline, and crystalline, for the gap-surface plasmon hybrid device, which features stronger light–matter interaction and has higher resonant SHG efficiencies than the asymmetric F–P cavity device at respective GST phases. This research reveals that GST-based dynamic SHG switches can be potentially employed in practical applications, such as microscopy, optical communication, and photonic computing in the nonlinear regime.

The "green transformation of the express" delivery industry in this study primarily refers to the adoption of green energy and environmentally friendly technologies in express delivery packaging, transportation, and recycling systems. This transformation can significantly enhance energy efficiency and reduce emissions in the express system, promoting the sustainable development of the entire industry. However, the progress of green transformation in China's express delivery industry has been impeded by various barriers. To address this, we propose a barrier analysis framework based on the Fuzzy Decision Making Trial and Evaluation Laboratory (DEMATEL) methodology to explore key obstacles to green transformation in the express industry. Our research aims to answer three main questions: (1) What are the key barriers to green transformation in China's express delivery industry? (2) How do these barriers interact and influence each other? (3) What strategic measures can be implemented to overcome these barriers? We first compile a list of barriers, innovatively proposing two new ones: "inadequate green standards in the express industry" and "suboptimal green packaging technology". Considering the ambiguity in expert input and the complex interactions among barriers, we employ fuzzy DEMATEL within an Interval Type 2 Fuzzy Sets (IT2FSs) environment to investigate the significance and causality of these barriers. This approach distinguishes our study from previous research by providing a more nuanced understanding of barrier interactions in the specific context of China's express delivery industry. Based on our analysis, we identify eight critical barriers and propose corresponding strategic measures. [ABSTRACT FROM AUTHOR]

For the inaccuracy of empirical heat loads for spindle thermal simulations,a thermal simulation analysis method onto motorized spindle unit is proposed.Firstly,the fluid-solid-heat coupling simulation model of the motorized spindle unit is established by Ansys Workbench,with the coolant dynamic heat transfer and thermal resistances of bearing inner-spindle shaft and outer rings-bearing housing being considered.Secondly,based on the simulation model,genetic algorithm is used to optimize and correct the heat generation values of spindle motor/beairngs and ambient heat transfer coefficients.The corrected values above are used as thermal loads for thermal simulation modeling of motorized spindle unit.Based on the model,the dynamic relationship between the heat dissipation power of the coolants and the heat generation power of spindle motor/beairngs is studied.Finally,the model accuracy is verified by the spindle temperature testing experiment.The results show that the optimization correction model can effectively improve the temperature field simulation accuracy of the motorized spindle unit,and the spindle structure and the coolant reach the optimal heat-heating balance when the coolant supply temperature is about 2℃ lower than the ambient temperature.

With the rapid development of urban transportation facilities, their construction inevitably encounters unfavorable conditions, such as rivers and lakes. When using the weir construction method to build transportation facilities in lakes, the design scheme for the pit slope excavation inside the cofferdam is related to the success or failure of the construction. In this study, the design scheme for pit excavations in lakes is discussed and analyzed using numerical simulation and on-site monitoring against the background of Jinji Lake Tunnel. The findings are as follows. (1) The greater the distance between the pit and the cofferdam, the smaller the impact of pit excavation on the cofferdam is; when the excavation depth is 10 m and the distance is more than 47 m, the deformation of the whole pile is less than 15 mm. (2) Under the condition that the platform width is kept the same, the smaller the height and width ratio is, the greater the safety factor will be, and under the condition that the height and width ratio is kept the same, the longer the platform width is, the greater the safety factor will be. (3) When the pit and cofferdam are far away from each other, different slope release design schemes have different effects on cofferdam deformation and stability. The results of this research can provide references and guidance for the design and construction of similar projects. [ABSTRACT FROM AUTHOR]

In the realm of modern energy systems, addressing the challenges of enhancing flexibility and efficiency under uncertain conditions is of paramount importance. This paper explores the stochastic multi-objective optimal multi-energy flow problem within the context of integrated electrical and heating systems (IEHS). First, the electrical network, the heating network, and the energy hubs were modeled in a completely linearized form. The linear weighted sum method with variable weights was used to transform the multi-objective problem into a single-objective problem and generate a large number of Pareto-optimal solutions. Second, the input stochastic variables were divided into multi-interval scenarios by employing the Cartesian product. For each interval scenario, the interval satisfaction degree level was proposed to convert the constraints involving interval numbers into deterministic ones. Third, a multiple attributes decision analysis (MADA) approach was proposed based on evidential reasoning theory. Six evaluation attributes, namely, the power purchase cost and pollution gas emissions of IEHS, the sum of power loss and sum of voltage deviation in the electrical system, the sum of temperature drop in the heating system, and the interval probability value of the multi-interval scenarios, were considered to rank the Pareto-optimal solutions collected from the multi-interval scenarios and determine the final dispatch solution (called the Utopia solution). Numerical simulations demonstrated that the Utopia solution can comprehensively evaluate various attributes, making it the most suitable option for meeting the operational requirements of IEHS. [ABSTRACT FROM AUTHOR]

In order to improve the cuttings transport ability and well hole purification effect of horizontal shale gas wells in the Sichuan and Chongqing area, a new type of aluminum alloy drill pipe is put forward, and the floatability is validated by theoretical analysis and actual parameter calculation. According to the cuttings migration mechanism, the cuttings cleaning simulation model of the new aluminum alloy drill pipe and the traditional steel drill pipe was established by Fluent, and the hexahedral mesh is used to divide the model. Thus, the mesh independence and convergence of the two models are verified. Then, the simulation model is verified by comparing the calculation results of the two simulation models with the experimental data of the indoor cuttings migration device. Finally, the rock-cleaning ability of the two drill pipes is analyzed under the conditions of changing the cuttings particle size, well inclination angle, displacement, and mechanical speed. Compared with the traditional steel drill pipe, the new aluminum alloy drill pipe can improve the borehole purification capacity by 13% on average. This research result is of great significance in reducing the quality of cuttings in the annulus and improving the borehole purification effect. [ABSTRACT FROM AUTHOR]

Here, we report the comparative study of enhanced second harmonic generation using defect engineering in pyramid-like MoS2 (P-MoS2) flakes to vertically aligned MoS2 (VA-MoS2) flakes. P-MoS2 and VA-MoS2 is synthesized via the modified chemical vapor deposition technique. The second harmonic generation measurements on P-MoS2 and VA-MoS2 are performed by sweeping the excitation wavelength from 1200 nm to 1310 nm in identical conditions. The P-MoS2 flakes show a high SHG signal. The high SHG signal in pyramid-like MoS2 is attributed to the broken inversion symmetry and high thickness of grown MoS2 flakes. VA-MoS2 flakes under the identical conditions show a 34% enhanced SHG signal in comparison to P-MoS2. The midgap states generated due to defects in the form of S vacancies in VA-MoS2 are responsible for this enhancement. These midgap states confine the photons and result in enhanced SHG properties. Our study will pave a new path to understand the role of 2D material morphology in fabricating versatile optical and photonics devices. [ABSTRACT FROM AUTHOR]