Conventional solidification theory asserts that eutectic phases solidify into only one specific morphology at a fixed undercooling when volume effects are negligible, while dendrites adopt rotationally parabolic tips. Here, experiments aboard China Space Station reveal that space fluid flow localization reshapes these dynamics: confined solute-thermal coupling near solid-liquid interfaces drives transitions among three eutectic growth patterns (worm-like, lamellar, faceted). Simultaneously, Marangoni convection at large undercoolings induces non-parabolic dendritic tip morphologies (dome-like, finger-like, needle-like). Spatially ordered separation of eutectic and dendritic zones is governed by localized spherically symmetric temperature and concentration fields arising from space fluid flow, whereas buoyancy-driven convection in terrestrial gravity environment disrupts this ordering, perturbing phase domain distributions. When solidified at a small undercooling, the weak convection during late stage preserves the near-perfect symmetry of dendrites under microgravity. These findings uncover novel dendritic and eutectic growth patterns under microgravity and may be applied to in-situ space manufacturing and controlled growth of crystals.

The eutectic growth kinetics and solidified microstructures of liquid Zr57V43 refractory alloy were explored aboard the China Space Station (CSS), where long-term microgravity state and confined fluid flow were ensured synchronously. The thermophysical properties were determined at both metastable undercooled liquid and high temperature solid states, which were hard to measure accurately on the ground. The solidified microstructures exhibited eutectic cells with a novel ripple-like characteristic under the effects of 10-5 g0 microgravity and 73 K undercooling. The eutectic growth velocity attained 4.59 mm & sdot;s-1 in this case. The ripple-like pattern was formed by the (Zr) and V2Zr phases developing alternatively from the surface towards the droplet center, resulting from suppressed convection around the nucleation sites. Anomalous eutectic was distributed inside the eutectic cells and the lamellar eutectic outside due to the eutectic growth kinetics change. The anomalous eutectic and finer lamellar eutectic respectively lead to an 11.7 % and 13.2 % increase in micro-indentation hardness of the Zr57V43 alloy compared with the levitationally solidified alloy at a similar undercooling on the ground. The research findings contribute to further understanding of novel microstructure formation and the performance change of eutectic alloys solidified in outer space.

The peritectic μ-Nb7Ni6 phase was prepared directly from liquid Nb54Ni46 alloy by melting spinning technique. The atomic resolution image reveals the presence of complex atomic arrangements, including both {0001} stacking faults and twins. Notably, the crystallographic slipping plane does not coincide with the crystallographic twinning plane of the {0001} twin. Furthermore, the density functional theory calculation indicates that the formation of the {0001} twin arises from the synergistic effect of slipping on (0006) crystallographic slipping plane with the Burgers vector b ​= ​1/3<1¯100>, combined with local atomic rearrangements at the 3a and 6c2 sites along the [0001] direction during slipping. Finally, the twinning mechanism of the {0001} twin was elucidated by integrating the atomic model of the μ-Nb7Ni6 phase, the atomic resolution images and density functional theory calculation results, the slipping of three consecutive neighboring (0006) planes along [1¯100] direction will form two adjacent {0001} twin interfaces separated by a distance of c.

Under the background of the construction of “new engineering” and the training mode of large-scale talents, combined with the characteristics of national defense, the orientation of subjects and the existing experimental teaching and scientific research conditions, we explored and reformed the curriculum system of experimental teaching for undergraduate majors of Applied Physics in our university. It mainly includes the construction of a professional experimental teaching system with national defense characteristics, the design of research-oriented modular series of experiments and the implementation of diversified assessment. Through exploration and practice, it has promoted the construction of national and provincial first-class undergraduate majors, improved students' innovation ability, cooperation ability and practical ability, stimulated military feelings, cultivated the spirit of scientists, and significantly improved students' comprehensive quality.

Molecular dynamics has become an important method to study the physical properties of liquid alloy, and has irreplaceable advantages in experimental research in many aspects. The accurate physical properties of liquid alloy in a wide temperature range can be obtained by employing the molecular dynamics, which is of great significance to expand the database of physical properties of liquid alloy and further deepening the understanding of high-temperature liquid alloy. Based on the type cases, the calculation process of the density, specific heat, diffusion coefficient and surface tension of liquid alloy have been heuristically introduced. The relationship between the outputs of molecular dynamics simulation with the macroscopic physical properties has been taught form the shallower to the deeper, and students' understands of this relationship are deepened by combining the computer experiments. After teaching reform and practice, the classroom contents of the physical properties of liquid alloy calculated by molecular dynamics can be vividly taught, and the teaching effect of the structure and properties of liquid alloy is also improved by using this teaching process design.

双体分布函数是表征液态金属结构的重要方法,对理解液态结构具有重要的作用.本文根据分布函数能够完整地描述随机变量统计规律的内涵,并且决定随机变量其他概率特征的基本属性,结合双体分布函数简洁的数学表达和抽象的物理表征,在课程教学过程中,从双体分布函数的物理意义入手,介绍了实验中测量双体分布函数的手段,同时讲解了计算模拟中双体分布函数的统计方法,并以液态金属Nb和液态Ni-Zr合金的前沿科技成果为例,分析了不同有序度双体分布函数的曲线特征,讲授了其中物理过程与数学模型的内在联系.以典型案例将双体分布函数与液态结构变化的知识同步传授,形象且深刻地讲解了双体分布函数在液态金属结构中的表征过程.

密度是十分基本且非常重要的物理量,但密度十分常见,因此在高温合金熔体性质教学和学习过程中,常常重视不够,以致影响对高温熔体性质的认识.本文根据高温合金熔体的基本物理化学性质,创新教学方法,精心进行教学过程设计,首先以航空发动机用Inconel718合金的固态和液态密度随温度的变化作为切入点,抓住学生的学习兴趣点,进而"有设计""有构思"地引出密度测定为什么难、如何进行实验测定、典型的密度变化规律等体系化的知识.这一教学过程设计生动形象地讲授了高温合金熔体密度的课堂内容,深化了液态金属结构与性质的教学效果.

In view of the frontier, cross and abstract course characteristics of liquid metal structure and properties, in order to implement the fundamental task of building morality and cultivating people, this paper introduces the exploration and practice of curriculum ideological and political education in the teaching of liquid metal structure and properties from two aspects of textbook construction and teaching process, focusing on the school-running characteristics and the talent training objectives of material physics. It focuses on how to combine the requirements of the Central Committee of the Party and the major strategic deployment of the country to carry out the textbook construction, fully excavate the core elements of the teaching process, integrate the ideological and political elements into the whole process of classroom teaching, and finally it summarizes the exploration and practice of teaching reform, teaching process design and teaching case selection.

As wearables, such as smartwatches and data gloves, become ubiquitous in our daily lives, it is possible to capture users' behaviors as they go, and then to authenticate them using biometrics. A variety of behaviors have been exploited to authenticate users in a plethora of scenarios. However, there is still a lack of systematic investigations on what types of behaviors present better performance for authentication, and therefore, limiting our understanding of the custom design of behavioral “passwords” to fit people's needs. This paper is designed to help answer this question. First, we design a collection of behaviors, which is used to explore the effect of different types of behaviors on authentication. This collection involves hand and finger behaviors since they are common and natural human actions; it also reasonably covers both basic movements and complex behaviors, two major categories of behaviors. We evaluated authentication performance along the dimensions of behaviors, users (sensitivity) and classification models (independence). A valuable finding shows that finger-issued movements present almost equivalent performance with complex behaviors. Therefore, it suggests applying them to the wearable and mobile devices as an alternative to complex behaviors, and could considerably reduce requirements for computational resources compared to complex behaviors. Furthermore, they extend the applications of behavioral authentication to a wider array of scenarios, like performing behavioral authentication such as moving fingers in one's pocket, which is common for wearable and mobile applications.

The mechanisms of microstructure evolution and dendritic growth of Inconel alloys in a drop tube were investigated in this paper. The Vickers microhardness of the solidified alloy droplets was also measured to explore the effects of grain size and precipitated phase on the mechanical properties. From XRD results, the rapidly solidified Inconel 600, 617, 625, and 718 alloys are characterized by γ phase solid solution with fcc structure. Further analyses based on EDS and SEM reveal that Laves phase precipitates at the grain boundaries of γ phase in Inconel 718 alloy. With the decrease of droplet diameter ( D ), the dendritic morphology experiences a transformation of “orthogonal long dendrites→irregular stubby dendrites→equiaxed grains” in Inconel 600 alloy, “orthogonal long dendrites → stubby irregular dendrites” in Inconel 625 alloy and “orthogonal long dendrites→equiaxed grains” in Inconel 617 and 718 alloys. Although the dendrites become coarse locally, the dendritic grain size obviously reduces with the decrease of droplet diameter, leading to the increase of Vickers microhardness. For Inconel 718 alloy, the Vickers microhardness firstly decreases, when the droplet diameter decreases from 1000 to 900 µm, and then increases linearly with the decrease of droplet diameter. It is found that the Vickers microhardness of Inconel 625 alloy is the largest among the four alloys.

Natural and convenient physiological health monitoring and the technology of health information sharing has important practical value in preventing the occurrence of disease and enhancing people's health level, this paper combines physiological health monitoring technology and mobile application technology, studying the mobile application of collaborative physiological health monitoring and sharing technology. Heart rate monitoring as a break-through point of health monitoring, this paper studies non-contact heart rate monitoring technology based on visible light and constructs the physiological signs network for group users. Finally, combined with mobile terminals and so-cial networking platforms, the paper achieves natural and convenient physiological health monitoring and community health information sharing for network relationship support.

Some key techniques are discussed for using the model-derived development method in aerospace domain.The AADL is used to build architecture model,environment model,behavior model,error model and execution model for aerospace software.Based on AADL model,the sourcing codes are generated automatically,which lightens the programming workload.The author manages to analyze and cheek its safety and sustainability by transforming ADDL model to fault tree and finite automata machine model.A aerospace domain models database can be developed to support large-scale re-use by software models.The framework of aerospace model-driven software development platform is also provided.And the space GNC system is used to verify the effectiveness of model-derived approach.

Human gesture is a natural and efficient way of human computer interaction.It has wide applications in smart home and intelligent transportation.The gestures with identical semantic may have multiple presentations in temporal and spatial dimensions,due to its derivatives on gesture speed,spatial constrains,and the user demographics.All of these bring a significant challenge to the recognition precision.This article presented a novel dynamic time warping (DTW) based recognition approach——spatial-temporal dynamic time warping(SDTW),which applies a decentralized slot method to achieve both adaptiveness to spatial and temporal multi-scale.A smartphone-based prototype system is developed,which exploits the accelerometer to capture the gesture and applies SDTW to do gesture recognition.The experiment shows that the SDTW can promote the recognition precision effectively.

Multimodal Tele-interaction aims to use a variety of interactive modal and collaborative way and complementary characteristics and information between multiple modal,to communicate and understand the user interaction desires,improve the efficiency of interaction,enhance the naturalness of interaction,and enable users to complete the remote tasks in their "expectations".Recently,with the applications of multimodal tele-interaction on the space exploration,deep sea exploitation and tele-surgery,the delay is introduced into the process of tele-interaction,which is produced mainly by the communication delay and bandwidth.The significant dalay causes the problems of asynchronous interaction and lack of interaction modal,which results a fundamental effect on the user's behavior,psychological and cognitive characteristics,breaks and blocks the continuity,real-time and naturalness of interaction,not only degrade interactive user experience,but also is difficult to guarantee validity.The article defined the concept of multimodal tele-interaction,presented its key applications,and discussed the key technology,including the delay issue,asynchronous interaction and lack of interaction modal.Finally,we presented research challenges in the future.

Android based smartphone users' privacy has been a hot issue recently in public concerns due to various instances of security attacks and privacy leakage on Android platform. Android existing security has been built upon a permission based mechanism which restricts critical resources accesses of third-party Android applications. This permission based security system is widely assessed for its major control of application permissions and critical management of permissions by developers, marketers, and end users. Considering the critical management of permissions some previous research papers proposed automatic permission management tools. But those automatic tools never assessed end user's expectation about permissions perfectly. This paper presents a tool, SDroid (Secured anDroid) that assesses the best permissions management based on end users opinion. SDroid evaluates requested permissions and allow users selectively grant permissions considering his/her knowledge level depending on the opinion.

The safety awareness online detection of driving behavior means that a kind of detection of the ongoing unsafe driving behavior as it starts but before it ends. This type of detection is significant important for achieving safe driving assistant because it is able to recognize the unsafe or aggressive driving behavior in advance and then give a buffer time to issue the vital alert. In order to achieve online detection, it is critical to reduce the processing time spent on the whole behavior recognition procedure, which usually is complex and involves a lot of computation loads. This paper proposes an approach to address the challenge by adopting a methodology of software and hardware co-design. We implement the most computation intensive stages of preprocessing and feature extraction as the hardware cores. A prototype safety awareness online behavior detection system is implemented on the programmable chip (SoPC) by using software and hardware co-design, and the experiment shows its effectiveness.

Frequent route is an important individual outdoor behavior pattern that many trajectory-based applications rely on. In this paper, we propose a novel framework for extracting frequent routes from personal GPS trajectories. The key idea of our design is to accurately detect road corners and utilize these new metaphors to tackle the problem of frequent route extraction. Concretely, our framework contains three phases: 1) characteristic point (CP) extraction; 2) corner detection; and 3) trajectory mapping. In the first phase, we present a linear fitting-based algorithm to extract CPs. In the second phase, we develop a multiple density level DBSCAN (density-based spatial clustering of applications with noise) algorithm to locate road corners by clustering CPs. In the third phase, we convert each trajectory into an ordered sequence of road corners and obtain all routes that have been traversed by an individual for at least ${F}$ (frequency threshold) times. We evaluate the framework using real-world trajectory datasets of individuals for one year and the experimental results demonstrate that our framework outperforms the baseline approach by 7.8% on average in terms of precision and 21.9% in terms of recall.

In order to improve the quality of Activity Recognition Chain (ARC) systems, an effective testing approach is required to evaluate the functionalities of their major components, especially for two kernel components, the segmentation and recognition components. Both of them largely utilize the machine learning algorithms to achieve the detection and recognition of activity correctly. The probabilistic nature of the machine learning algorithms present severe challenge to the testing for the ARC systems. The article adopts a MT (metamorphic testing) methodology to address this topic. We analyze the MR (metamorphic relation) between the results of segmentation and recognition components. Based on this kind of MR, we propose a two-stage MT based approach for the testing of ARC systems, which exploits the association fact between segmentation and recognition, and then performs the MT testing on them respectively in sequence. This approach is able to deal with the specific issues in ARC systems testing, and provides a general method for systems testing with probabilistic nature.

With the rapid development of mobile application′s market, how to efficiently test and verify the quality of mobile applications has become one research focus in current academia and industry. In particular, due to the types of mobile devices, technology updates faster; how to test compatibility for mobile applications is an urgent problem. We propose a new mobile application testing method based on testing?value?weight semantic tree model. The method can drive all testing environments of mobile applications and then rank and select appropriate environ?ments with the testing values. The experiments have proved the feasibility of the proposed method, which can reduce the amount of compatibility testing environmental configuration, thus improving the efficiency of testing and reducing the testing cost and time.