Search

In the field of many-objective evolutionary optimization algorithms (MaOEAs), how to maintain the balance between convergence and diversity has been a significant research problem. With the increase of the number of objectives, the number of mutually nondominated solutions increases rapidly, and multi-objective evolutionary optimization algorithms, based on Pareto-dominated relations, become invalid because of the loss of selection pressure in environmental selection. In order to solve this problem, indicator-based many-objective evolutionary algorithms have been proposed; however, they are not good enough at maintaining diversity. Decomposition-based methods have achieved promising performance in keeping diversity. In this paper, we propose a MaOEA based on indicator and decomposition (IDEA) to keep the convergence and diversity simultaneously. Moreover, decomposition-based algorithms do not work well on irregular PFs. To tackle this problem, this paper develops a reference-points adjustment method based on the learning population. Experimental studies of several well-known benchmark problems show that IDEA is very effective compared to ten state-of-the-art many-objective algorithms. [ABSTRACT FROM AUTHOR]

This work is geared toward a real-world manufacturing planning (MP) task, whose two objectives are to maximize the order fulfillment rate and minimize the total cost. More important, the requirements and constraints in real manufacturing make the MP task very challenging in several aspects. For example, the MP needs to cover many production components of multiple plants over a 30-day horizon, which means that it involves a large number of decision variables. Furthermore, the MP task’s two objectives have extremely different magnitudes, and some constraints are difficult to handle. Facing these uncompromising practical requirements, we introduce an interactive multiobjective optimization-based MP system in this article. It can help the decision maker reach a satisfactory tradeoff between the two objectives without consuming massive calculations. In the MP system, the submitted MP task is modeled as a multiobjective integer programming (MOIP) problem. Then, the MOIP problem is addressed via a two-stage multiobjective optimization algorithm (TSMOA). To alleviate the heavy calculation burden, TSMOA transforms the optimization of the MOIP problem into the optimization of a series of single-objective problems (SOPs). Meanwhile, a new SOP solving strategy is used in the MP system to further reduce the computational cost. It utilizes two sequential easier SOPs as the approximator of the original complex SOP for optimization. As part of the MP system, TSMOA and the SOP solving strategy are demonstrated to be efficient in real-world MP applications. In addition, the effectiveness of TSMOA is also validated on benchmark problems. The results indicate that TSMOA as well as the MP system are promising. [ABSTRACT FROM AUTHOR]

Hugoniot equation-of-state data of shock compressed beta-Si4Al2O2N6 are determined to a pressure of 120 GPa. A comparison of the Hugoniot data and recovered samples suggests that the high-pressure CaTi2O4-type phase is not quenchable and quenched as an amorphorus phase although a large hysteresis is detected in the release path.

In recent years, gas tests in Benxi Formation in the south-central Ordos Basin have shown good oil and gas displays. In 2009, a gas reservoir was encountered in the Benxi Formation during drilling by the Shanxi Yanchang Petroleum Company, and the open flow potential was estimated at over a million cubic meter per day. Thus, studying the reservoirs in this area is of great exploration and guidance significance. In the paper, reservoirs were studied by casting thin sections, scanning electron microscopy, and high-pressure mercury intrusion experiments, and then, a diagenetic evolution sequence was established. Combined with the recovery model of the initial porosity of the sandstone and a quantitative pore analysis technique, the quantitative porosity evolution model of the Benxi Formation reservoir was established. The results show that i) the Benxi Formation mainly includes quartz sandstone, with less lithic quartz sandstone and lithic sandstone; ii) In general, five types of pores are generally developed in the Benxi Formation, namely, residual intergranular pores, intergranular dissolution pores, intercrystalline pores, micropores and microfractures; iii) Reservoir development was mainly affected by sedimentation and diagenesis; iv) At present, the main reservoir has currently reached the end of the mid-diagenesis of the B stage or late diagenesis stage. The average primary porosity of the sandstone was approximately 38.1%. The reservoir underwent a porosity reduction stage due to strong compaction, a porosity reduction stage due to early cementation, a porosity enhancement stage due to dissolution and a porosity reduction stage due to late cementation. The average porosity of the reservoir is now 4.89%. [ABSTRACT FROM AUTHOR]

Hugoniot measurements are performed up to 180 GPa on fully dense, polycrystalline aluminum oxynitride spinel (AlON) from Raytheon to determine the equations of state and to investigate possible high-pressure transformations. The phase transition to CaTi2O4-type structures implies that the Si3N4 spinel can also be transformed into a CaTi2O4-type phase with increasing pressure.

It is well known that traditional microstrip (MS) transmission lines suffer from high transmission losses at microwave and millimeter wave frequencies. To solve the issue, a novel periodic subwavelength structure is proposed in this work with semi-elliptical grooves (SEGs) on a lateral edge of MS line, for the propagation of spoof surface plasmon polaritons (SSPPs) in the microwave regime. Dispersion relations are analyzed by a numerical method using ANSYS's HFSS (High-Frequency Structure Simulator), and ability to operate efficiently in primary mode is demonstrated. A comparison with other structures is also accomplished and found that more strong resonant modes are created by the coupling between upper metal strip with textured SEGs and the lower ground layer which are confined near the surface of this grating structure. It has been observed that the cutoff frequency (fc) and the level of field confinement depend on the geometric parameters, and SEG-based SSPPs efficiently minimize the asymptotic frequency by 65% and 12% as compared to MS and Vee-groove structures, respectively. We further investigate a planar and highly efficient, low-pass plasmonic filter with 3 dB cutoff frequency of 11.4 GHz and significantly reduced insertion loss (>−1.9 dB) in the passband. A prototype is fabricated for validation by standard PCB manufacturing process; good agreement between experimental and simulation results confirms the excellent performance of this compact filter in the entire passband with smaller transmission losses. Such a plasmonic metamaterial structure presents a unique and highly unexplored geometry which strongly supports confined SSPPs, therefore, can play a significant role in advanced integrated plasmonics circuitry and applications. [ABSTRACT FROM AUTHOR]

Domain patterning thin ferroelectric films creates nonlinear optical devices. Unfortunately, pinholes cause conventional electrical domain-poling methods to short circuit when used on thin film. We have applied a focused ion beam (FIB) to pattern the ferroelectric domains of LiNbO3 single crystalline films with thicknesses of 800 nm–2 μm. FIB can fabricate domains 100 times faster than a scanning probe microscope and can be applied to irregular surface structures. Furthermore, FIB is compatible with semiconductor device processing techniques, which paves the way for monolithic nonlinear photonic integrated circuits in ferroelectrics. [ABSTRACT FROM AUTHOR]

Diamond-like carbon (DLC) is a form of amorphous carbon which has high fraction of sp3 hybridization. Due to its nature of sp3 bonding, diamond-like carbon has been shown to have excellent properties similar to that of diamond. This includes high hardness, excellent wear-resistance, large modulus and chemically inert. Traditional applications include wear resistant coatings and protective film. This article intends to review the synthesis and material properties of diamond-like carbon as well as its potential as a novel material for applications in nano-architecture and nano-mechanical devices. An introduction into metal-dopants in diamond-like carbon film will be briefly mentioned as well as techniques on the design and fabrication of this material. [ABSTRACT FROM AUTHOR]

Abstract: Patterned ferroelectric domains and domain selective etching of the patterned domains can provide ferroelectrics-based photonic crystals. In this paper, electron-beam has been applied to switch domains in LiNbO3 (LN) and LiTaO3 (LT) crystals. The complex dynamics of interaction of beam electrons with the crystals has been highlighted. Based on this research, an improved e-beam domain patterning technique utilizing resist covering is successfully applied to switch domains in a z-cut 1mol% MgO-doped stoichiometric LN at room temperature. [Copyright &y& Elsevier]

The ferromagnetic transition temperatures have been measured on two bathes of perovskite manganese oxides such as (La1- x R x )2/3Ca1/3MnO3(R=Ce, Pr, Nd, etc.) and La2/3(Ca1- y Cd y )1/3MnO3. It is found that the (La1- x R x )2/3Ca1/3MnO3 samples have obviously different Curie temperature T C although their (rA) (the average A-site cation radius) are almost identical, and the T C in the system of (La1- x R x )2/3Ca1/3MnO3(R=Ce, Pr, Nd, etc.) and La2/3(Ca1- y Cd y )1/3MnO3. It is found that the (La1- x R x )2/3Ca1/3MnO3 compounds increases with increasing y although (rA) decreases slightly. It is suggested that the Curie temperature should be influenced by the average local A-site magnetic moment in the ferromagnetic perovskite manganite system. [ABSTRACT FROM AUTHOR]

The electrical resistance in zero magnetic field and magnetoresistance in different external magnetic fields have been measured in a temperature range of 77—300 K. It is found that the temperature dependence of magnetoresistance can be well described by a phenomenofogical formula of where the fitting parameters α, β vary as the external magnetic field H changes, E 0 is the activation energy, E 0/ k B = 1160 K, M s is the saturation magnetization, the temperature and magnetic field dependence of M/ M s is obtained by the mean-field expression. [ABSTRACT FROM AUTHOR]

Cutting planes (cuts) play an important role in solving mixed-integer linear programs (MILPs), which formulate many important real-world applications. Cut selection heavily depends on (P1) which cuts to prefer and (P2) how many cuts to select. Although modern MILP solvers tackle (P1)-(P2) by human-designed heuristics, machine learning carries the potential to learn more effective heuristics. However, many existing learning-based methods learn which cuts to prefer, neglecting the importance of learning how many cuts to select. Moreover, we observe that (P3) what order of selected cuts to prefer significantly impacts the efficiency of MILP solvers as well. To address these challenges, we propose a novel hierarchical sequence/set model (HEM) to learn cut selection policies. Specifically, HEM is a bi-level model: (1) a higher-level module that learns how many cuts to select, (2) and a lower-level module-that formulates the cut selection as a sequence/set to sequence learning problem-to learn policies selecting an ordered subset with the cardinality determined by the higher-level module. To the best of our knowledge, HEM is the first data-driven methodology that well tackles (P1)-(P3) simultaneously. Experiments demonstrate that HEM significantly improves the efficiency of solving MILPs on eleven challenging MILP benchmarks, including two Huawei's real problems.

Purpose: To explore whether texture features based on magnetic resonance can distinguish diseases combined hepatocellular-cholangiocarcinoma (cHCC-CC) from hepatocellular carcinoma (HCC) before operation., Methods: The clinical baseline data and MRI information of 342 patients with pathologically diagnosed cHCC-CC and HCC in two medical centers were collected. The data were divided into the training set and the test set at a ratio of 7:3. MRI images of tumors were segmented with ITK-SNAP software, and python open-source platform was used for texture analysis. Logistic regression as the base model, mutual information (MI) and Least Absolute Shrinkage and Selection Operator (LASSO) regression were used to select the most favorable features. The clinical, radiomics, and clinic-radiomics model were constructed based on logistic regression. The model's effectiveness was comprehensively evaluated by the receiver operating characteristic (ROC) curve, area under the curve (AUC), sensitivity, specificity, and Youden index which is the main, and the model results were exported by SHapley Additive exPlanations (SHAP)., Results: A total of 23 features were included. Among all models, the arterial phase-based clinic-radiomics model showed the best performance in differentiating cHCC-CC from HCC before an operation, with the AUC of the test set being 0.863 (95% CI: 0.782 to 0.923), the specificity and sensitivity being 0.918 (95% CI: 0.819 to 0.973) and 0.738 (95% CI: 0.580 to 0.861), respectively. SHAP value results showed that the RMS was the most important feature affecting the model., Conclusion: Clinic-radiomics model based on DCE-MRI may be useful to distinguish cHCC-CC from HCC in a preoperative setting, especially in the arterial phase, and RMS has the greatest impact., Competing Interests: The authors report no conflicts of interest in this work., (© 2023 Guo et al.)

Lithium niobate on insulator (LNOI) photonics promises to combine the excellent nonlinear properties of lithium niobate with the high complexity achievable by high contrast waveguides. However, to date, fabrication challenges have resulted in high-loss and sidewall-angled waveguides, limiting its applicability. We report LNOI single mode waveguides with ultra low propagation loss of 0.4 dB/cm and sidewall angle of 75°. Our results open the route to a highly efficient photonic platform with applications ranging from high-speed telecommunication to quantum technology.