功能梯度金属泡沫填充管在冲击载荷下的高效吸能

研究功能梯度泡沫填充管(FGFTs)在落锤冲击载荷作用下的变形行为和耐撞性.采用液态工艺制备的闭孔泡沫铝、A356合金泡沫和锌泡沫作为轴向梯度填料,用于制备不同构造的单层和多层结构.结果表明,多层泡沫填充管的变形由低强度部位开始,然后通过应力的逐渐增加在高强度部位中扩展.使用更多的A356合金和泡沫铝层可为梯度结构提供...     

Gold nanocages in cancer diagnosis,therapy, and theranostics: A brief review

Regarding the increasing number of cancer patients, the global burden of this disease is continuing to grow. Despite a considerable improvement in the diagnosis and treatment of various types of cancer, new diagnosis and treatment strategies are required. Nanotechnology, as an interesting and advanced field in medicine, is aimed to further advance both cancer diagnosis and treatment. Gold nanocages (AuNCs), with hollow interiors and porous walls, have received a great deal of interest in various biomedical applications such as diagnosis, imaging, drug delivery, and hyperthermia therapy due to their special physicochemical characteristics including the porous structure and surface functionalization as well as optical and photothermal properties. This review is focused on recent developments in therapeutic and diagnostic and applications of AuNCs with an emphasis on their theranostic applications in cancer diseases.     

Stabilization of gas-lift oil wells by a nonlinear model predictive control scheme based on adaptive neural network models

Producing oil from gas-lift wells are often faced with severe producing oscillatory flow regimes. A major source of the oscillations is recognized as casing–heading instability which is caused by dynamic interaction between injection gas and multiphase fluid. This phenomenon poses strict production-related challenges in terms of lower average production and strain on downstream equipment. In this paper, an effective solution is proposed based on integration of an online interpretation dynamic model and a nonlinear model predictive control (NMPC) scheme. The paper uses adaptive growing and pruning radial basis function (GAP-RBF) neural networks (NNs) to recursively capture the essential dynamics of casing–heading instability in a nonlinear model structure. Extended Kalman filter (EKF) and unscented Kalman filter (UKF) are comparatively investigated to adaptively train modified GAP-RBF NNs. NMPC methodology is developed on the basis of the identified nonlinear NN model for real-time stabilization of casing–heading instability in an oil reservoir equipped with a gas-lift production well. A set of test studies has been conducted to explore the superior performance of the proposed adaptive NMPC controller under different scenarios for an oil reservoir simulated in ECLIPSE and linked to a complementary gas-lifted oil well simulated in programming environment.     

Taguchi统计学分析方法优化Al 7068-TiC纳米复合材料的凝固行为

采用机械合金化和热压工艺制备高强Al 7068?5%TiC(质量分数)纳米复合材料。基于致密化的重要性和晶粒生长的影响,以获得较高抗压强度为目标,采用Taguchi统计法对制备Al 7068?5%TiC块体纳米复合材料的热压条件进行优化。结果表明：在500 MPa和385°C下热压30 min能获得抗压强度为938 MPa、硬度为HV 265的Al 7068?TiC纳米复合材料。此外,方差分析结果表明,外加压力是影响纳米复合材料热压过程最关键的因素。各因素对纳米复合材料热压过程影响贡献率为外加压力(61.3%)、热压温度(29.53%)和热压时间(4.49%)。     

Bioactive properties of Kilka (<Emphasis Type="Italic">Clupeonella cultriventris caspi</Emphasis>) fish protein hydrolysates

Whole common Kilka fish was hydrolyzed separately using four commercial enzymes, Alcalase, Neutrase, Protamex at 50 °C and Pepsin at 37 °C for 30, 60 and 90 min. Degree of hydrolysis, angiotensin-I-converting enzyme (ACE) inhibitory activity and antimicrobial activity of each hydrolysate against Gram-negative (Escherichia coli, Salmonella enteritidis) and Gram-positive (Staphylococcus aureus, Listeria innocua) bacteria were studied. Results showed that the degree of hydrolysis for all enzymes was in the range of 2.63–3.36%. Electrophoresis profiles of the Kilka protein hydrolysates showed that most of produced peptides were in the range of 30 D but Alcalase and Neutrase had a better performance in the production of low molecular weight peptides in the range of 10 D. This led to increase the antimicrobial activity against the examined bacteria at the concentration of 200 µg/mL peptide solution. The Neutrase enzyme produced hydrolysate with the highest ACE inhibitory activity (53%?±?1.8 at 500 µg/mL). Antimicrobial activity of Kilka protein hydrolysates using Protamex and Pepsin was lower than the others due to lack of considerable amount of small peptides. The current research has demonstrated that the peptides derived from the enzymatic hydrolysis of Kilka fish protein in optimum conditions are capable of being converted to antimicrobial and antihypertensive agents to be used in functional foods.     

Comments on ‘ Commutativity of second-order time-varying systems ’

The conditions for commutativity of two second-order time-varying systems presented recently (Köksal 1982) are shown not to be necessary. Necessary and sufficient conditions are presented for the commutativity of two time-varying systems, from a certain class of systems of order not greater than two.     

High-Entropy Alloy-Induced Metallic Glass Transformation: Challenges Posed by in situ Alloying via Additive Manufacturing

In situ alloying and fabricating glassy structures through a layer-by-layer fashion approach are challenging but have high potential to develop novel-graded materials. For the first time, this cost-effective approach is applied to additive manufacturing (AM) of a Zr-based bulk metallic glass (BMG) from high-entropy alloys (HEAs). A newly developed composition of Zr₄₀Al₂₀Cu₂₀Ti₂₀ is fabricated through laser powder bed fusion (LPBF). Process parameters are optimized within a wide range of laser power (50–200 W) as well as scanning speed (50–800 mm s⁻¹). In all printed samples, microscopic and compositional examinations reveal no glass formation, but very fine grains and CuTi and AlTi nanocrystals. Some glassy transitions at the interfaces may be encouraged to occur with proper melting and mixing. However, the main reason for not obtaining a glassy matrix is the substantial proportion of unmelted Zr raw powder throughout the structure as spherical particles. Consequently, glass formation can be hindered by a considerable amount of compositional deviation. During LPBF, in situ alloying poses significant challenges to developing BMGs. Hence, the various stages of the process, including raw material specifications, laser settings, and process parameters, should be investigated further.     

Influence of high velocity oxy-fuel parameters on properties of nanostructured TiO<Subscript>2</Subscript> coatings

A liquid fuel high velocity oxy-fuel (HVOF) thermal spray process has been used to deposit TiO₂ nanostructured coatings utilizing a commercially available nanopowder as the feedstock. The coatings were characterized by means of X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM), respectively. Photocatalytic activity was evaluated as a rate constant of decomposition reaction of methylene blue (MB) determined from the changes of relative concentration of MB with UV irradiation time. The results indicate that the sprayed TiO₂ coatings were composed of both TiO₂ phases viz. anatase and rutile, with different phase contents and crystallite sizes. A high anatase content of 80% by volume was achieved at 0·00015, fuel-to-oxygen ratio with nanostructure coating by grain size smaller than feedstock powder. Photocatalytic activity evaluation results indicated that all the TiO₂ coatings are effective to degradation MB under UV radiation and their activities differ in different spray conditions. It is found that fuel flow rate strongly influenced on phase transformation of anatase to rutile and by optimizing the rate which can promote structural transformation and grain coarsening in coating and improving photocatalytic activity.     

Modeling Framework and Decomposition Scheme for On‐Demand Mobility Services with Ridesharing and Transfer

This article presents a modeling framework for the operations of on‐demand mobility services (ODMS) in urban areas. The framework provides the capabilities to analyze ODMS operations while representing emerging services such as ridesharing and transfer. The problem is formulated as a mixed integer program and an efficient decomposition‐based methodology is developed for its solution. The methodology adopts a modified version of the column generation algorithm, which implements iterative decomposition and network augmentation techniques to allow studying networks of moderate size. The results of a set of experiments considering grid and real‐world networks are presented. The results show that increasing the number of passengers willing to rideshare and/or transfer improves the overall performance of ODMS as it increases number of served passengers and associated profit and reduces the number of used vehicles. Although presented as an offline planning tool, the methodology could be adopted for real‐time applications as adequate computational resources become available.     

搅拌摩擦技术制备AA6061/SiC纳米复合材料的工艺参数优化(英文)

采用搅拌摩擦技术制备AA6061/SiC纳米复合材料,并用实验设计方法来确定影响AA6061/SiC复合材料极限拉伸强度的重要因素,包括4种因素,即旋转速度、横向速度、切削深度、搅拌头形状。运用Taguchi方法,得到优化的工艺参数。方差分析表明,旋转速度是最主要的影响因素。统计分析结果表明,采用带螺纹的搅拌头得到的复合材料的极限拉伸强度比采用方型搅拌头的高。搅拌头的旋转速度越快、横向速度越慢,则复合材料的极限拉伸强度越高。