Which Surrogate Works for Empirical Performance Modelling? A Case Study with Differential Evolution

It is not uncommon that meta-heuristic algorithms contain some intrinsic parameters, the optimal configuration of which is crucial for achieving their peak performance. However, evaluating the effectiveness of a configuration is expensive, as it involves many costly runs of the target algorithm. Perhaps surprisingly, it is possible to build a cheap-to-evaluate surrogate that models the algorithm's empirical performance as a function of its parameters. Such surrogates constitute an important building block for understanding algorithm performance, algorithm portfolio/selection, and the automatic algorithm configuration. In principle, many off-the-shelf machine learning techniques can be used to build surrogates. In this paper, we take the differential evolution (DE) as the baseline algorithm for proof-of-concept study. Regression models are trained to model the DE's empirical performance given a parameter configuration. In particular, we evaluate and compare four popular regression algorithms both in terms of how well they predict the empirical performance with respect to a particular parameter configuration, and also how well they approximate the parameter versus the empirical performance landscapes

FLEXURAL PERFORMANCE OF COLD-FORMED THIN-WALLED STEEL-PAPER STRAW BOARD COMPOSITE SLAB

A new type of composite slab was proposed by connecting paper straw board and cold-formed thin-walled steel with self-tapping screws. In order to investigate the failure process and failure mode of the composite slab, the tests on the flexural capacity of three composite slabs with different factors such as steel beam section size, beam spacing and the number of screws were carried out. The strain of the cold-formed thin-walled C-shaped steel and the paper straw board, and the deflection of the composite slab were observed, respectively. Moreover, the flexural behaviour and the composite action of the composite slab were investigated and the flexural capacity of the composite slab was obtained. It was found that the final failure mode of composite slab was the local buckling mode of cold-formed thin-walled C-shaped steel beam due to the adequate restraint of the straw board, and the reducing of the screw spacing had beneficial influence on the flexural yield capacity. The calculation method of midspan deflection and flexural capacity of composite slab were proposed, and the calculated values of deflection and flexural capacity agreed well with the test results. Therefore, the new composite slabs were of good working performance and high flexural capacity

Low-Complexity Constrained Recursive Kernel Risk-Sensitive Loss Algorithm

The constrained recursive maximum correntropy criterion (CRMCC) combats the non-Gaussian noise effectively. However, the performance surface of maximum correntropy criterion (MCC) is highly non-convex, resulting in low accuracy. Inspired by the smooth kernel risk-sensitive loss (KRSL), a novel constrained recursive KRSL (CRKRSL) algorithm is proposed, which shows higher filtering accuracy and lower computational complexity than CRMCC. Meanwhile, a modified update strategy is developed to avoid the instability of CRKRSL in the early iterations. By using Isserlis’s theorem to separate the complex symmetric matrix with fourth-moment variables, the mean square stability condition of CRKRSL is derived, and the simulation results validate its advantages

Low-Complexity Constrained Recursive Kernel Risk-Sensitive Loss Algorithm

The constrained recursive maximum correntropy criterion (CRMCC) combats the non-Gaussian noise effectively. However, the performance surface of maximum correntropy criterion (MCC) is highly non-convex, resulting in low accuracy. Inspired by the smooth kernel risk-sensitive loss (KRSL), a novel constrained recursive KRSL (CRKRSL) algorithm is proposed, which shows higher filtering accuracy and lower computational complexity than CRMCC. Meanwhile, a modified update strategy is developed to avoid the instability of CRKRSL in the early iterations. By using Isserlis’s theorem to separate the complex symmetric matrix with fourth-moment variables, the mean square stability condition of CRKRSL is derived, and the simulation results validate its advantages

Effect of Heat Input on Microstructure and Properties of Laser-Welded 316L/In601 Dissimilar Overlap Joints in High-Temperature Thermocouple

Heat input, a crucial factor in the optimization of high-temperature thermocouple laser welding, has a significant impact on the appearance and mechanical properties of dissimilar welded joints involving stainless-steel- and nickel-based alloys. This study focuses on laser overlay welding of austenitic stainless steels and nickel-based alloys. The findings indicate that an increase in heat input has a more pronounced effect on the penetration depth and dilution rate. Under high heat input, the weld has cracks, spatter, and other defects. Additionally, considerable amounts of chromium (Cr) and nickel (Ni) elements are observed outside the grain near the crack, and their presence increases with higher heat input levels. Phase analysis reveals the presence of numerous Cr2Fe14C and Fe3Ni2 phases within the weld. The heat input increases to the range of 30–35 J/mm, and the weld changes from shear fracture to tensile fracture. In the center of the molten pool, the Vickers hardness is greater than that of the base metal, while in the fusion zone, the Vickers hardness is lower than that of the base metal. The overall hardness is in a downward trend with the increase of heat input, and the minimum hardness is only 159 HV0.3 at 40 J/mm. The heat input falls within the range of 28–30 J/mm, and the temperature shock resistance is at its peak

Toxicity Assessment of PEG-PCCL Nanoparticles and Preliminary Investigation on Its Anti-tumor Effect of Paclitaxel-Loading

Abstract The efficiency of single treatment of conventional chemotherapy drugs is unpleasantly reduced by the physiological barriers of tumors. In this regard, nanoparticles have become attractive for achieving such medical purpose of targeted cancer therapy by delivering anti-tumor agents to the needed area. A novel drug deliverer, poly (ethylene glycol) carboxyl-poly (ε-caprolactone) (PEG-PCCL), has been reported to be highly hydrophilic and stable, while little is known about its organic toxicity. This study focused on systemic toxicity assessments of PEG-PCCL. The pharmacokinetics of PTX-loaded PEG-PCCL (PEG-PCCL/PTX) and its anti-tumor effect were preliminarily investigated. In the present work, PEG-PCCL was characterized by laser particle size analyzer and transmission electron microscopy. The cytotoxicity was investigated by MTT test, LDH leakage assay, immunofluorescence, and transmission electron microscopy. Hemolysis, phlebitis, and organ toxicity tests were performed to demonstrate the biocompatibility and acute biotoxicity. H22 tumor-bearing mice were used to evaluate the pharmacokinetics of the micells of PEG-PCCL/PTX and its anti-tumor effect. The results showed that the size of PEG-PCCL nanospheres was 97 ± 2.6 nm. PEG-PCCL treatment showed little cytotoxicity and good biocompatibility, and did not exhibit organ toxicity. PTX-loading efficiency was 49.98%. The pharmacokinetic study on H22 tumor-bearing mice revealed that PEG-PCCL/PTX has higher stability and slower release than PTX alone. Together, these results suggest that PEG-PCCL nanosphere has little toxicity to organisms and is a potential candidate of biocompatible drug vehicle for hydrophobic drugs

Improving anti‐Gram‐positive‐bacterial performance and osteogenesis for zinc alloy via mussel mimetic polydopamine with non‐antibiotic lysozyme and parathyroid hormone

Abstract In this work, a novel coating with a non‐antibiotic agent for inhibiting Gram‐positive bacteria and promoting osteogenesis was prepared on zinc‐aluminium alloy (ZA6‐1) via mussel mimetic polydopamine (PDA) containing lysozyme (LYS) and parathyroid hormone (PTH). The results indicate that as‐deposited coatings can efficiently decrease the degradation rate of ZA6‐1 from 0.52 to 0.16 mm/year, and the addition of LYS weakens the coating resistance, while the addition of PTH enhances the coating resistance. In spite that no obvious inhibition of Escherichia coli is observed, the coated zinc alloys show good in vitro antibacterial performance against Staphylococcus aureus. Compared with ZA6‐1 zinc alloys, the increase of antibacterial efficacy reaches 86.9%–90.1%. Furthermore, the lower hydrophilicity (26.4°), higher osteoblast cell viability (>100%), good osteoblast cell morphology and better osteoblast cell differentiation (ALP = 107.7%) for PDA‐LYS/PTH coated samples support that as‐prepared coating is promising for modifying biodegradable zinc implants