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Investment casting plays a pivotal role in the fabrication of complex and precise components, notably turbine blades for aerospace and energy industries. During the casting process, the non-uniform shell thickness distribution affects the dimensional accuracy and surface quality, and further impact the performance and reliability of the products. This study delves into the effects of turbine blade casting system design, focusing on shell thickness uniformity and its correlation with casting dimensional accuracy. Through an experimental setup that manipulates wax pattern attitude angles and module diameters, coupled with the Industrial Computed Tomography (ICT) for non-destructive thickness measurement, this study uncovers the critical role of centrifugal effects during the slurry application in modulating shell thickness uniformity. Our findings reveal that strategic adjustments to the wax pattern attitude angle and module diameter can significantly enhance shell thickness uniformity, thereby potentially increasing the structural integrity and dimensional precision of turbine blades. In addition, a positive correlation between shell inhomogeneity and casting manufacturing deviation was found through casting profile inspection and correlation analysis. This research not only elucidates the relationship between manufacturing parameters and shell formation but also proposes practical adjustments to the casting system design, offering new pathways to refine investment casting processes for high-value components.

The in-situ TiB2particle reinforced aluminum matrix composites are materials that are difficult to machine, owing to hard ceramic particles in the matrix. In the milling process, the polycrystalline diamond (PCD) tools are used for machining these materials instead of carbide cutting tools, which significantly increase the machining cost. In this study, ultrasonic vibration method was applied for milling in-situ TiB2/7050Al metal matrix composites using a TiAlN coated carbide end milling tool. To completely understand the tool wear mechanism in ultrasonic-vibration assisted milling (UAM), the relative motion of the cutting tool and interaction of workpiece-tool-chip contact interface was analyzed in detail. Additionally, a comparative experimental study with and without ultrasonic vibration was carried out to investigate the influences of ultrasonic vibration and cutting parameters on the cutting force, tool life and tool wear mechanism. The results show that the motion of the cutting tool relative to the chip changes periodically in the helical direction and the separation of tool and chip occurs in the transverse direction in one vibration period, in ultrasonic vibration assisted cutting. Large instantaneous acceleration can be obtained in axial ultrasonic vibration milling. The cutting force in axial direction is significantly reduced by 42%–57%, 40%–57% and 44%–54%, at different cutting speeds, feed rates and cutting depths, respectively, compared with that in conventional milling. Additionally, the tool life is prolonged approximately 2–5 times when the ultrasonic vibration method is applied. The tool wear pattern micro-cracks are only found in UAM. These might be of great importance for future research in order to understand the cutting mechanisms in UAM of in-situ TiB2/7050Al metal matrix composites.

A coupled cellular automaton-finite element model was developed to simulate the solidification behavior and structure of 38CrMoAl large round bloom, in which mold electromagnetic stirring + final electromagnetic stirring was taken into consideration, under different superheat, casting speeds, and secondary cooling water flow. Industrial trials for infrared temperature measurement and macro etch experiments of the post-test round bloom samples were used to verify the simulated solidification structure and temperature field. The simulation results show that superheat and secondary cooling water flow have little influence on the surface temperature, center temperature, and center solid fraction while casting speed has a more obvious influence on solidification behavior. With the increase in the casting speed of 0.02 m min−1, the solidification position is prolonged by about 1.64 m. With the increasing specific water ratio by 0.02 L kg−1each, the surface temperature of the secondary cooling zones decreases by about 18 °C, and the solidification position shortens by about 0.11 m. As the superheat increases from 10 to 40 °C, the ratio of the equiaxed crystal zone decreases from 35.98% to 23.98%. The casting speed and secondary cooling water flow increase the equiaxed crystal ratios of the large round bloom, but neither is significant, both being about 2%.

Model reconstruction is crucial in blade repair because it directly determines the shape precision and finish of a repaired surface. However, owing to insufficient surface data pertaining to defective regions and the unique deformation caused by harsh environments, modeling a worn blade remains difficult. Hence, a model reconstruction method for worn blades is developed in this study. Unlike conventional methods of constructing and interpolating sectional curves, the proposed method focuses on modifying a nominal computer aided design (CAD) model to reconstruct the worn blade. Through weighted rigid registration and constraint-based non-rigid registration, the design surface extracted from the nominal CAD model can be deformed to align with the surface data of the worn blade without a significant loss of its initial shape. Verification results show that the deformed design surface exhibits sufficient smoothness and accuracy for guiding tool path generation in the subsequent blade repair.

As an advanced material, ceramic matrix composites have attracted attention due to their superior properties, such as low density, high strength, and high-temperature resistance. However, it is also a typical difficult-to-cut material with the reinforcement and matrix material being of high hardness and brittleness, which makes the manufacturing of this kind of material an urgent problem. Ultrasonic vibration-assisted machining technique has advantages in decreasing cutting force, reducing tool wear, and improving machinability, making it suitable for machining hard and brittle difficult-to-cut materials. This paper has investigated ultrasonic vibration-assisted milling-grinding SiC fiber reinforced ceramic matrix composite. It aims to understand the feasibility of machining this advanced material and tool performance. Experimental results found that the ultrasonic vibration-assisted machining technique with the proper tool would be a suitable method for this advanced material. The self-designed polycrystalline diamond compact tool had a better performance and tool life. Its tool life was 4.11 times, 12 times, and 50.63 times as long as commonly used 50 mesh brazed diamond tool, 200 mesh brazed diamond tool and 100 mesh electroplated diamond tool, respectively. For a smaller cutting force and tool wear, machining parameters of a more considerable spindle speed, lower feed speed, and small cutting depth would be suggested, with ultrasonic amplitude being 4 μm and frequency being 30 kHz.

Embryo rescue technology plays an important role in seedless grape breeding. However, the efficiency of embryo rescue, including the embryo formation, germination, and seedling rates, is closely related to the parental genotypes, degree of abortion, growth medium, and plant growth regulators. In this study, we investigated the effects of different concentrations of paclobutrazol (PAC), a plant growth regulator, and embryo collection times on the embryo formation, germination, and seedling rates for different hybrid combinations of grape breeding varieties used for their aroma and cold-resistance traits. The results showed that the different PAC concentrations had varying impacts on the development of ovules and embryos from the different grape varieties. The embryo formation rates of the ‘Sultanina Rose’בBeibinghong’ and ‘Kunxiang Seedless’בTaishan-2’ crosses were the highest under the 5.1 μmol L−1PAC treatment. The 1.0 μmol L−1PAC treatment was optimal for the germination and seedling development of the ‘Sultanina Rose’בBeibinghong’ embryos, whereas the 0.2 μmol L−1PAC treatment induced the highest germination rate for the ‘Sultanina Rose’בKunxiang Seedless’ cross. The optimal sampling times for each cross varied as 39 d after pollination (DAP) for the ‘Flame Seedless’בMuscat Hamburg’ cross, 46 DAP for the ‘Kunxiang Seedless’בBeibinghong’ cross, and 41 DAP for the ‘Ruby Seedless’בBeibinghong’ and ‘Fantasy Seedless’בShuangyou’ crosses. Moreover, the medium modified with 0.5 g L−1of indole-3-butyric acid allowed the malformed seedlings to develop into plantlets and achieve larger progenies. This study provides a useful basis for further studies into grape embryo rescue and could improve breeding efforts for new seedless grape varieties.

As a typical refractory material, the DD6 nickel-based single-crystal superalloy has important applications in the aviation industry. Ultrasonic-assisted drilling is an advanced machining method that significantly improves machining of refractory materials. The drilling thrust force influences the hole surface quality, burr height, and bit wear. Therefore, it is necessary to predict the thrust force during ultrasonic-assisted drilling. However, there are few reports on the modeling of the thrust force in the ultrasonic-assisted drilling of micro-holes. A thrust force prediction model for ultrasonic-assisted micro-drilling is proposed in this study. Based on the basic cutting principle, the dynamic cutting speed, dynamic cutting thickness, and acoustic softening effect caused by ultrasonic vibrations are factored into this model. Through model calibration, the specific friction force and specific normal force coefficients were determined. The model was verified through ultrasonic-assisted drilling experiments conducted at different feed rates, spindle speeds, frequencies, and amplitudes. The maximum and minimum errors of the average thrust force were 10.5% and 2.3%, respectively. This model accurately predicts the thrust force based on the parameters used for ultrasonic-assisted micro-hole drilling and can assist in the analysis and modeling of DD6 superalloy processing.

Traditional processing methods have been used to relieve toxicity and enhance a calming effect of Polygalae Radix(PR). However, up to now, there is no comprehensive study on the changes of saponins, aromatic acids, and so on (from relatively big molecules to small molecules). Here, a novel processing-omics (PO) strategy was reported. It cleverly integrated the non-targeted and targeted chemomics technology, and the simulated processing method of compounds for mining original markers, to rapidly and comprehensively evaluate mechanisms of chemical transformation among PR, PR with refined honey (HP), and PR with licorice(LP). In this strategy, the advanced ultra-high performance liquid chromatography coupled with quadrupole time-of-flight data-independent mass spectrometry (UHPLC-Q-TOF-MSE) and HPLC platform were employed to study and collect chemical composition data of PR processing. And the combination of QI and UNIFITMsoftware was designed to analyze relatively big molecules for PR, HP and LP sequentially, avoiding a waste of time for the identification of extra non-markers. A total of 57 relatively big markers were identified. Six small aromatic acids were quantified by targeted chemomics, as critical markers. Importantly, the hydrolysis mechanisms of saponins, isomerization of xanthones and glycolipids, and intact mechanisms of transformation, were reported by a combination of above chemomics and the simulated processing method. This study provided a rapid and comprehensive guidance to further study on processing procedures, chemical mechanisms, and construction of quality standards.

Investment casting is a complex process with multiple procedures. Predicting the dimensional accuracy of products and identifying defect parts at the early manufacturing stage is vital yet challenging. Physical simulation is commonly used for analyzing the part deformation during the casting process. However, it is usually timing consuming, thus not suitable for applications during the manufacturing process. This paper proposes a data-driven framework for estimating and screening defect products at the early stage based on ensemble learning techniques. Taking the geometrical relationship of the intermediate and the final products into consideration, a feature derivation and selection method is firstly developed. Then, an ensemble machine learning model is proposed for high prediction accuracy with the integration of multiple machine learning models. Validation experiment outcomes for the case of aircraft hollow turbo blade manufacturing indicate that the proposed prediction method can accurately predict the wall thickness of the final parts based on wax patterns and effectively identify the unqualified intermediate parts at the early stage. In this way, the production yield rate could be improved, and the cost of the production could be reduced.

ABSTRACTObjectives: Multilevel noncontiguous thoracic and lumbar spinal tuberculosis (MNST) is a relatively rare entity. The objective of this retrospective study was to investigate whether a technique involving a one-stage posterior debridement and decompression, combined with an intervertebral fusion and posterior instrumentation, is effective for treating MNST.Methods: Thirteen patients, with an average age of 40.69 (18–67) years, who had MNST and were surgically treated in our department from January 2008 to October 2013, were reviewed.Results: The average follow-up time was 37.54 ± 10.49 (19–58) months. The mean Cobb angle range was 15.69° ± 00A09.09° (−3° to 33°). The mean erythrocyte sedimentation rate (ESR) was 47.69 ± 9.30 mm/h (range 30–62 mm/h) before the operation. Neurological deficits were evaluated using the Frankel grade system. The mean Cobb angle decreased to 6.92° ± 3.93° postoperatively. Three months after the operation, the Cobb angle was 7.54° ± 4.35°, and the average ESR was 10.38 ± 4.54 mm/h that was normal for all cases in this retrospective observational study. Solid fusion was achieved in all cases. No severe complications occurred.Conclusions: The study demonstrated that a one-stage posterior debridement and decompression, combined with an intervertebral fusion and posterior instrumentation, was effective for treating MNST.

The structure of the thin liquid films determines the stability of foams and emulsions. In this work the bubbles stretched length with different hollow SiO2 particles concentration is measured when the foam has been stilled for different time. The results show that the bubbles stretched length is longer than that of bubbles when the foam is free of hollow SiO2 particles even when the foam has been stilled for 500mins. The bubbles stretched length increases with increasing the concentration of hollow SiO2 particles. A strong hydration effect leaves a large volume of hydration layers on the solid particles surfaces in aqueous solutions. The water in hydration layers can help the film keep a certain thickness. The existence of hydration forces leads that two particles cannot be too close each other. The high concentration surfactant limited in the fixed area helps the film keep good elasticity. Therefore the film has a long life time with compatible thickness and elasticity and the three-phrase foam is upper stable.

Ceramic core shifting during the filling process of investment casting is one of the key factors that influence the wall thickness accuracy of hollow turbine blades. Although plenty of study has conducted to analyze and control the wall thickness accuracy, the mechanism of core shifting has rarely taken much attention. To fill this gap, this paper firstly analyze the movement of ceramic core under the casting condition combining computational fluid dynamics and motion simulation. Then, the shifting mode and final position of ceramic core were predicted based on the time-varying load in investment casting filling process. Afterwards, a casting experiment was conducted to verify the proposed prediction method and the results show a good match. In addition, a wax pattern reverse compensating approach was devised and validated based on the prediction result. After correction, the maximum displacement of the ceramic core has lowered by 51.6 %, indicating that the suggested approach is successful in improving the wall thickness accuracy.

•Machinability of brand new TiB2particles reinforced Al-MMC were investigated.•The main tool wear mechanisms are abrasive and adhesive.•Small surface roughness was obtained compared to SiC/Al MMCs.•The machinability is better than SiC/Al MMCs.

A hydrophobic surface was fabricated on a micro-arc oxidation (MAO) treated AZ31 Mg alloys via surface modification with myristic acid. The effects of modification time on the wettability of the coatings were investigated using the contact angle measuring device. The surface morphologies and structure of the coatings were evaluated using SEM, XRD and FT-IR. The corrosion resistance was investigated by potentiodynamic polarization curves and long-term immersion test. The results showed that the water contact angle (CA) increases gradually with modification time from 0 to 5 h, the highest CA reaches 138° after being modified for 5 h, and the number and size of the micro pores are decreased. The modification method hardly alters crystalline structure of the MAO coating, but improves the corrosion resistance based on the much positive potential and low current density. Moreover, the corrosion resistance and hydrophobicity can be enhanced with increasing the alkyl chain. The wetting and spreading for the alkylcarboxylate with low surface energy become easier on the micro-porous surface, and alkylcarboxylate monolayer will be formed through bidentate bonding, which changes the surface micropores to a sealing or semi-sealing structure and makes the MAO coating dense and hydrophobic. All the results demonstrate that the modification process improves the corrosion protection ability of the MAO coating on AZ31B Mg alloy.

In large-scale urban adaptation and real estate development process, some protective cultural relic buildings and modern excellent architecture face the reality of being demolished, that will produce a large number of construction rubbish, pollute the environment , at the same time, cause a large number of resources waste. In this paper, the application of monolithic moving technique of building is introduced, which can not only save nature resources, but also maximum reduce pollution to the environment.

Engineering science is bridge of fundamental science and engineering. This paper introduces origin, growth and figuration of engineering science by examining its history, and defines it as science-based engineering theory, or science-abstracted engineering theory by comparing concepts related. Finally, roles, which engineering science play for a nation, are discussed including increasing productivity, providing solutions for national security, and advancing science and technology. The authors suggest more recognition of fundamental science, talent cultivation from Chinese perspective.

A novel image encryption scheme comprising of one permutation process and one diffusion process is proposed. In the permutation process, the image sized is expanded to one sized by dividing the plain-image into two parts: one consisting of the higher 4bits and one consisting of the lower 4bits. The permutation operations are done row-by-row and column-by-column to increase the speed. The chaotic generalized Arnold map is utilized to generate chaotic sequence, which is quantized to shuffle the expanded image. The chaotic sequence for permutation process is dependent on plain-image and cipher keys, resulting in good key sensitivity and plain-image sensitivity. To achieve more avalanche effect and larger key space, Chinese Remainder Theorem is applied to diffuse the shuffled image. The key sensitivity and key space of the proposed image encryption have been analyzed as well. The experimental results suggest that the proposed image encryption scheme can be used for secure image and video communication applications.

In this paper, the NiCu alloy coatings were electroplated on the 304 stainless steel coupon. The XRD was used to identify the phase structure of the as-prepared products. The SEM and EDS were used to observe the surface morphology of the as-prepared coatings and the atomic composition of the as-prepared coatings, respectively. The influences of the current density on the as-plated NiCu coatings are systematically researched. It was found that the moderate current density is beneficial to the compactness of the coatings. The content of the copper decreased and that of the nickel increased with the increasing of the current density. When the current density is smaller than 40 mA/cm2, the contents of nickel and copper vary apparently. When the current density is larger than 40 mA/cm2, the contents of nickel and copper vary slightly. That means the copper is more easily deposited at low current density and the nickel is more easily deposited at high current density.

A color image watermarking scheme using the chaotic properties of 2D tent map and Chebyshev map is proposed. Given control parameters and initial values, one can iterate the 2D tent map to get one chaotic sequence and obtain one permutation by sorting the chaotic sequence in ascending order. The permutation is then utilized to shuffle the blue channel components of color image as a preprocessing stage to enhance the security, imperceptibility and robustness of watermarking. Meanwhile, one can iterate the Chebyshev map to generate another chaotic sequence to determine the embedding bit positions and strengthen the security as well. Experiment results show that the watermarking scheme is secure with large key space, imperceptible and robust against cropping, noise attacks.

Elastic modulus of a coating is an important property for design and use of the coating. At present, many methods have been put forward to evaluate the coating elastic modulus. However, each methods has special property, which make the elastic moduli from them are different. In the study, elastic modulus of a porous Ti coating has been evaluated by three-point bending test and indentation method. The results show that the coating elastic moduli from the two different methods agree well, which can reflect the uniformity of the pore structures of the porous coating. Meanwhile, the little deviations among the different test points of indentation method could reflect the uniformity of the coating structure partly.

A duplex-layered phosphate conversion coating was obtained on AZ31Mg alloy through a phosphate bath with citric. Morphology, composition and corrosion behavior of the coating immersed into 3.5% NaCl solution for various time were investigated using scanning electron microscopy (SEM), X-ray diffractometer (XRD) and electrochemical method. The results show that the coating is completely degraded after immersed in NaCl solution for 48h. The corrosion mediums mainly peel coating through the cracks among particles. The phosphate coating is damaged and falls out primarily, then the intermediate layer is degraded, and the substrate happens to dissolve with increasing of immersion time.

In this paper, the NiCu alloy coatings were electroplated on the 304 stainless steel coupon. The XRD was used to identify the phase structure of the as-prepared products. The SEM and EDS were used to observe the surface morphology of the as-prepared coatings and the atomic composition of the as-prepared coatings, respectively. The influences of the pH value on the as-plated NiCu coatings are systematically researched. It was found that the weak acid environment was beneficial to the deposition of nickel copper alloy. With the increasing of the pH value, the content of the copper decrease and that of nickel increase.