Creep fracture behaviour of SUS304H steel with vanadium addition based on small punch creep testing

The high-temperature creep fracture behaviour and creep strength of SUS 304H containing a minor addition of V were investigated in this study. A series of small punch (SP) creep and uniaxial creep tests were performed at 700 °C. The load and punch displacement rates obtained from the SP creep tests were used to derive conversion equations to determine the equivalent stress and creep strain rates. A converting equation is suggested in this study so that Norton’s secondary power law creep constants obtained from the SP creep testing can be in agreement with those obtained from the uniaxial tensile creep tests. The creep strength of the modified SUS 304H steel containing V was shown to be superior to that without V based on the current results and other available results for type 304H steel.     

Two‐Terminal Multibit Optical Memory via van der Waals Heterostructure

2D van der Waals (vdWs) heterostructures exhibit intriguing optoelectronic properties in photodetectors, solar cells, and light‐emitting diodes. In addition, these materials have the potential to be further extended to optical memories with promising broadband applications for image sensing, logic gates, and synaptic devices for neuromorphic computing. In particular, high programming voltage, high off‐power consumption, and circuital complexity in integration are primary concerns in the development of three‐terminal optical memory devices. This study describes a multilevel nonvolatile optical memory device with a two‐terminal floating‐gate field‐effect transistor with a MoS₂/hexagonal boron nitride/graphene heterostructure. The device exhibits an extremely low off‐current of ≈10^?14 A and high optical switching on/off current ratio of over ≈10⁶, allowing 18 distinct current levels corresponding to more than four‐bit information storage. Furthermore, it demonstrates an extended endurance of over ≈10⁴ program–erase cycles and a long retention time exceeding 3.6 × 10⁴ s with a low programming voltage of ?10 V. This device paves the way for miniaturization and high‐density integration of future optical memories with vdWs heterostructures.     

Tailored Heterojunction Active Sites for Oxygen Electrocatalyst Promotion in Zinc-Air Batteries

Rechargeable zinc-air batteries (ZABs) are promising energy storage systems due to their low-cost and safety. However, the working principle of ZABs is based on oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), which display sluggish kinetic and low stability. Herein, this work proposes a novel method to design a heterogeneous CoP/CoO electrocatalyst on mesopore nanobox carbon/carbon nanotube (CoP/CoO@MNC-CNT) that enriched active sites and synergistic effect. Moreover, the well-defined heterointerfaces could lower the energy barrier for intermediate species adsorption and promote OER and ORR electrochemical performances. The CoP/CoO@MNC-CNT electrocatalyst presents a high half-wave potential of 0.838 V for ORR and a small overpotential of 270 mV for OER. The ZABs-based CoP/CoO@MNC-CNT air-cathode shows an open-circuit voltage of 1.409 V, the long-term cycle life of 500 h with a small voltage difference change of 7.7%. Additionally, the flexible ZABs exhibit highly mechanical stability, demonstrating their application potential in wearable electronic devices.     

Numerical solution of multi-variable order fractional integro-differential equations using the Bernstein polynomials

In practice, computer simulations cannot be perfectly controlled because of the inherent uncertainty caused by variability in the environment (e.g., demand rate in the inventory management). Ignoring this source of variability may result in sub-optimality or infeasibility of optimal solutions. This paper aims at proposing a new method for simulation–optimization when limited knowledge on the probability distribution of uncertain variables is available and also limited budget for computation is allowed. The proposed method uses the Taguchi robust terminology and the crossed array design when its statistical techniques are replaced by design and analysis of computer experiments and Kriging. This method offers a new approach for weighting uncertainty scenarios for such a case when probability distributions of uncertain variables are unknown without available historical data. We apply a particular bootstrapping technique when the number of simulation runs is much less compared to the common bootstrapping techniques. In this case, bootstrapping is undertaken by employing original (i.e., non-bootstrapped) data, and thus, it does not result in a computationally expensive task. The applicability of the proposed method is illustrated through the Economic Order Quantity (EOQ) inventory problem, according to uncertainty in the demand rate and holding cost.

     

Novel wide‐beam cross‐dipole CP antenna for GNSS applications

A wide‐beam circularly polarized (CP) cross‐dipole antenna for GNSS applications is proposed in this article. This cross‐dipole antenna is fed by a coaxial cable, on which the slots is added to optimize the impedance matching. These two pairs of dipole arms are designed with different lengths to obtain the circularly polarized radiation. Enhanced wide‐beam CP radiation characteristics can be achieved by curving the dipole arms and adjusting the distance between the arms and the metallic ground plane. The study of proposed antenna performance with different geometric parameters has been conducted. The final antenna exhibits a good impedance bandwidth (IBW) of ～13.1% (1.50‐1.71 GHz), and the 3‐dB axial‐ratio bandwidth is over 7% (1.52‐1.64 GHz). Broad pattern coverage of more than 140°, pure CP radiation at all designed bands and a wide 3 dB axial‐ratio beamwidth (ARBW) of nearly 150° makes this antenna an excellent candidate for satellite communications and navigation systems.     

A secure image steganography based on modified matrix encoding using the adaptive region selection technique

This paper introduced an image steganography technique based on modified matrix encoding to enhance the perceptual quality of the stego images. Additionally, more pixel bit-planes are exploited in the data hiding process to improve the embedding capacity. The number of used image layers depends on the size of the given secret message and the texture characteristic of the cover image. The complexity of the pixel block is identified by the difference between the middle pixel and its neighbors. By performing the suitable embedding solutions of modified matrix encoding, the complexity is unchanged by the data hiding stage. Therefore, the used image regions could be determined precisely in the extraction process without using any additional information. The experimental results proved that the stego images created by the proposed approach achieved higher security against statistical and visual steganalysis techniques than the previous methods. The improvement of the security against detection by Ensemble Classifier is four times as secure as the best security performance of the existing methods.

     

A valences-totaling model for English sentiment classification

Sentiment classification plays an important role in everyday life, in political activities, activities of commodity production and commercial activities. Finding a time-effective and highly accurate solution to the classification of emotions is challenging. Today, there are many models (or methods) to classify the sentiment of documents. Sentiment classification has been studied for many years and is used widely in many different fields. We propose a new model, which is called the valences-totaling model (VTM), by using cosine measure (CM) to classify the sentiment of English documents. VTM is a new model for English sentiment classification. In this study, CM is a measure of similarity between two words and is used to calculate the valence (and polarity) of English semantic lexicons. We prove that CM is able to identify the sentiment valence and the sentiment polarity of the English sentiment lexicons online in combination with the Google search engine with AND operator and OR operator. VTM uses many English semantic lexicons. These English sentiment lexicons are calculated online and are based on the Internet. We present a full range of English sentences; thus, the emotion expressed in the English text is classified with more precision. Our new model is not dependent on a special domain and training data set—it is a domain-independent classifier. We test our new model on the Internet data in English. The calculated valence (and polarity) of English semantic words in this model is based on many documents on millions of English Web sites and English social networks.     

Preparation of Al2O3–AlN–Ni Composites

A method is proposed to prepare Al₂O₃-AlN-Ni composites. The composites are prepared by sintering Al₂O₃/NiAl powder mixtures at 1600°C in a mixture of nitrogen and carbon monoxide. The presence of NiAl particles raises the green density of Al₂O₃/NiAl powder compacts. During sintering, NiAl reacts with nitrogen to form AlN and Ni inclusions. A volume expansion accompanies the reaction. Because of the high green density and the reaction, the volume shrinkage of the Al₂O₃-AlN-Ni composite decreases with the increase of added NiAl content.     

Pressure-volume-temperature properties for binary and ternary polymer solutions of poly(ethylene glycol), poly(propylene glycol), and poly(ethylene glycol methyl ether) with anisole

Pressure-volume-temperature properties were measured for polymer solutions of poly(propylene glycol) (PPG)+anisole, polymer blends of PPG+poly(ethylene glycol methyl ether) (PEGME), and the blends of PPG+PEGME and poly(ethylene glycol) (PEG)+PPG with anisole at temperatures from 298.15 to 348.15 K and pressures up to 50 MPa. The Tait equation represents accurately the pressure effect on the liquid densities over the entire pressure range. The excess volumes change from positive to negative as increasing the mole fraction of PPG in the binary systems of PPG+anisole and PPG+PEGME. The volumetric data of the related binary systems were correlated with the Flory-Orwoll-Vrij and the Schotte equations of state to determine the binary parameters. By using these determined binary parameters, both equations predicted the specific volumes of the polymer blends with anisole to average absolute deviations of better than 0.13%.     

我国民营企业员工工作压力和组织承诺 相关关系实证研究

工作压力是影响员工组织承诺进而影响工作行为的一项重要因素.紧张的工作活动,沉重的工作负担,往往会在不同程度上影响到员工的组织承诺,进而影响组织效能.因此,对于现代组织而言,应该弄清楚各种压力源对组织承诺的影响程度,做到有针对性地采取策略来降低员工的工作压力水平.以此为出发点,通过实证研究调查民营企业员工的工作压力与工作态度之间的相关关系,从而依据研究结论,提出了压力管理的相应建议对策.