A hybrid damage model for simulating adiabatic shear bands

International Journal of Fracture - Adiabatic shear band (ASB) is one of the most important failure modes under high strain-rate deformation. In this work, we propose a hybrid damage model to...     

Suitability Evaluation of Cultivated Land Reserved Resources in Arid Areas Based on Regional Water Balance

With rapid socioeconomic and population growth, high-quality arable land resources are decreasing daily, especially in arid areas, which makes arable land reserve resources an important way to supplement arable land. How to accurately evaluate cultivated land reserve resources is of great significance to socioeconomic development and sustainable land use in arid areas. Therefore, this study selected Hangjin Banner as a typical area and calculated the regional maximum available irrigation water based on the principle of regional water balance. Then, the "irrigation area check algorithm" was used to evaluate the amount of cultivated land reserve resources, and policy recommendations were proposed for the development and utilization of cultivated land resources. The results showed that Hangjin Banner had no cultivated land reserve resources under the current irrigation method and had cultivated land reserve resources under the efficient water-saving irrigation method, but only in the southern zone during normal and partially abundant water years. Therefore, we believe that arid areas should adhere to the "set land by water" principle, the allocation of water resources should be optimized, and cultivated land resources with high quality should be utilized based on the actual regional conditions.

     

Failure Prediction of Municipal Water Pipes Using Machine Learning Algorithms

Pipe failure prediction has become a crucial demand of operators in daily operation and asset management due to the increase in operation risks of water distribution networks. In this paper, two machine learning algorithms, namely, random forest (RF) and logistic regression (LR) algorithms are employed for pipe failure prediction. RF algorithm consists of a group of decision trees that predicts pipe failure independently and makes the final decision by voting together. For the LR algorithm, the mapping relationship between existing data and decision variables is expressed by the logistic function. Then, the prediction is made by comparing the conditional probability with the fixed threshold value. The proposed algorithms are illustrated using an actual water distribution network in China. Results indicate that the RF algorithm performs better than the LR algorithm in terms of accuracy, recall, and area under the receiver operating characteristic curve. The effects of seven characteristics on pipe failures are analyzed, and diameter and length are identified as the top two influential factors.

Graphical Abstract

     

Eco-friendly and degradable red phosphorus nanoparticles for rapid microbial sterilization under visible light

Pathogens pose a serious challenge to environmental sanitation and a threat to public health.The frequent use of chemicals for sterilization in recent years has not only caused secondary damage to the environment but also increased pathogen resistance to drugs,which further threatens public health.To address this issue,the use of non-chemical antibacterial means has become a new trend for environmental disinfection.In this study,we developed red phosphorus nanoparticles(RPNPs),a safe and degradable photosensitive material with good photocatalytic and photothermal properties.The red phosphorus nanoparticles were prepared using a template method and ultrasonication.Under the irradiation of simulated sunlight for 20 min,the RPNPs exhibited an efficiency of 99.98%in killing Staphylococcus aureus due to their excellent photocatalytic and photothermal abilities.Transmission electron microscopy and ultraviolet–visible spectroscopy revealed that the RPNPs exhibited degradability within eight weeks.Both the RPNPs and their degradation products were nontoxic to fibroblast cells.Therefore,such RPNPs are expected to be used as a new type of low-cost,efficient,degradable,biocompatible,and eco-friendly photosensitive material for environmental disinfection.     

计及Spark和属性权重的售电套餐推荐方法

针对电力市场用户群庞大，交易过程中售电套餐选择困难的问题，在Spark环境下设计了一种售电套餐推荐方法，同时也解决了售电套餐推荐过程中在大数据环境下的可扩展性及实时性问题。首先，计算出每个套餐属性的权重值，从而计算得到售电套餐综合相似度。然后，计及用户和套餐两方面提出一种售电套餐推荐方法，实现售电套餐的精准推荐。实验表明，提出的推荐方法能够明显提高推荐的准确度，并且在分布式环境下具有良好的推荐效率和可扩展性。     

Electrical oscillation generation with current-induced resistivity switching in VO2 micro-channel devices

We report large amplitude modulation waveforms as large as ~ 10 V using vanadium dioxide micro-channel devices operating under current-controlled conditions. The self-sustained electrical oscillations were generated by controlling the applied current in the negative differential resistance region of the investigated devices. An appropriate value of internal capacitance was achieved as parasitic capacitance in the device structure to stabilize the electrical oscillations. This eliminates the need of an external pulsed source or any external passive component connected to the micro-channel devices. Amplitude and frequency of the oscillation were tuned by illuminating the device micro-channel with an external laser. An equivalent circuit model was developed to simulate the waveforms. A good agreement between experiment and simulation was verified.     

柱塞卡滞原因分析

某柱塞泵工作中发生柱塞卡滞,经显微形貌观察、光谱分析、电子探针面扫描分析和显微硬度分析等,确定柱塞卡滞的根本原因为原材料组织中存在严重的网状共晶碳化物,降低了强度和韧性,增大了柱塞球面表层的脆性,进而导致了球面部位的接触疲劳抗力下降。严重的疲劳磨损与接触疲劳造成了柱塞球面脱层破坏,由此产生的金属碎屑进入柱塞与衬套的配合间隙处,进而限制了柱塞的自由运动。