Structural optimization with an automatic mode identification method for tracking the local vibration mode

Traditional optimization methods, which take a specific order of modal frequency as the design constraint, could fail to obtain the desired solution because of modal substitution. An improved optimization model with continuous sizing variables is established to solve this problem, in which the minimum weight and a given local modal frequency are considered as the objective and the constraint. To capture accurately the expected mode of vibration, a local mode identification technique is proposed based on the strain energy ratio between the local area and the whole structure. With that scheme, an optimization system is developed, in which the local mode can be effectively identified and the constraint can be updated with it in the iteration process. Two numerical examples, of a reinforced plate and a satellite structure, are applied to illustrate the effectiveness and efficacy of the proposed method.     

基于船载卫星通信三轴天线的跟踪搜索技术

针对船载卫星通信三轴天线跟踪系统,介绍了船载三轴天线的系统组成,提出了一种基于捷联惯导的船载三轴天线跟踪搜索技术。天线以目标地理角为中心,通过坐标转换将目标地理角转换为天线的目标甲板角,调整AEC三轴使其及时准确地跟随目标甲板角。目前,该方法已经成功应用于多种船载三轴天线。实践表明,该方法能够快速准确地搜索到目标卫星,并实现对目标卫星的稳定跟踪。     

阳泉矿区煤样不同应力状态下声发射特性分析

为探索原煤煤样的力学性能和不同应力状态下的声发射活动特性,对阳泉矿区新景矿、平舒矿主采煤层的煤样进行了单轴、三轴压缩和巴西劈裂的声发射试验,分析了2种煤样力学性能及不同加载过程的声发射活动规律。证明通过监测声发射(微震)活动分析煤样或煤岩体内部破坏状态是一种方便有效的手段。     

基于SSM框架的大坝监测数据管理系统设计

针对目前大坝安全监测存在数据不能实时计算分析、展示,长期运行产生的大量数据主要靠人工整编且易出错等问题,结合现代信息化技术手段,以Java作为服务开发语言,设计了基于Spring+SpringMVC+Mybatis(SSM)框架的大坝安全监测数据管理平台,用于大坝监测数据的管理和分析,实现数据采集、存储、查询、计算分析、绘图、生成报表报告、实时监控及远程展示等功能,同时亦为监测仪器管理提供了可视化界面,方便仪器管理。结果表明,基于SSM框架的大坝安全监测数据管理系统实时反馈效果好,操作便捷,数据存取性能好、可视化程度高,便于大坝监测数据的管理与实时分析,为大坝安全运行与决策提供支撑。     

A spectrally selective surface structure for combined photothermic conversion and radiative sky cooling

The sun and outer space are the ultimate heat and cold sources for the earth, respectively. They have significant potential for renewable energy harvesting. In this paper, a spectrally selective surface structure that has a planar polydimethylsiloxane layer covering a solar absorber is conceptually proposed and optically designed for the combination of photothermic conversion (PT) and nighttime radiative sky cooling (RC). An optical simulation is conducted whose result shows that the designed surface structure (i.e., PT-RC surface structure) has a strong solar absorption coefficient of 0.92 and simultaneously emits as a mid-infrared spectral-selective emitter with an average emissivity of 0.84 within the atmospheric window. A thermal analysis prediction reveals that the designed PT-RC surface structure can be heated to 79.1°C higher than the ambient temperature in the daytime and passively cooled below the ambient temperature of approximately 10°C in the nighttime, indicating that the designed PT-RC surface structure has the potential for integrated PT conversion and nighttime RC utilization.     

Applied data science in patient-centric healthcare: Adaptive analytic systems for empowering physicians and patients

We define the emerging research field of applied data science as the knowledge discovery process in which analytic systems are designed and evaluated to improve the daily practices of domain experts. We investigate adaptive analytic systems as a novel research perspective of the three intertwining aspects within the knowledge discovery process in healthcare: domain and data understanding for physician- and patient-centric healthcare, data preprocessing and modelling using natural language processing and (big) data analytic techniques, and model evaluation and knowledge deployment through information infrastructures. We align these knowledge discovery aspects with the design science research steps of problem investigation, treatment design, and treatment validation, respectively. We note that the adaptive component in healthcare system prototypes may translate to data-driven personalisation aspects including personalised medicine. We explore how applied data science for patient-centric healthcare can thus empower physicians and patients to more effectively and efficiently improve healthcare. We propose meta-algorithmic modelling as a solution-oriented design science research framework in alignment with the knowledge discovery process to address the three key dilemmas in the emerging “post-algorithmic era” of data science: depth versus breadth, selection versus configuration, and accuracy versus transparency.     

CFD modeling of thermal contact resistance between solid contacting surfaces

Heat transfer has considerable applications in different industries such as designing of heat exchanger, nuclear reactor cooling, control system for spacecraft, and designing of microelectronics cooling. As the surfaces of two metals contact each other, this issue becomes so crucial. Thermal contact resistance (TCR) is one of the key physical parameters in heat transfer of mentioned surfaces. Measuring the experimental value of TCR in laboratory is highly expensive and difficult. As an alternative, numerical modeling methods could be engaged. In this study, inverse problem method solution is utilized as a proper method for estimation of TCR value. In this order, three different configurations (flat-flat, flat-cylinder, and cylinder-cylinder) were utilized in two steady and unsteady state conditions to predict the value of TCR. A comparison between the measured values and obtained values from the simulation show the errors for flat-flat, flat-cylinder, and cylinder-cylinder configuration after 10 min from starting the experiment are 4.6074%, 0.1662%, and 0.5622%, respectively. And in steady-state condition, the corresponding errors are 6.06e-3%, 1.506%, and 0.846%, respectively. In conclusion, the final results establish the fact that the inverse problem method solution can predict TCR values between contacting surfaces.     

Exergy analysis of the diesel pre-reforming solid oxide fuel cell system with anode off-gas recycling in the SchIBZ project. Part I: Modeling and validation

Solid oxide fuel cell (SOFC) systems with anode off-gas recirculation (AGR) and diesel pre-reforming are advantageous because they can operate with the current fuel infrastructure. In the SchIBZ-project, the prototype of such a SOFC system for maritime applications has already been commissioned. In this first paper, we model the system devices to conduct an exergy analysis of this real SOFC plant and validate them with experimental values from experiments in laboratory scale. The results of our simulation agree well with the experimental values. The calculations with the validated results may be closer to the real thermodynamic behavior of such system components than previous literature.     

Developing microencapsulated 12‐hydroxystearic acid (HSA) for phase change material use

Phase change materials (PCM) have an increasingly more important role as a thermal energy storage (TES) media. However, leakage problem of PCM causes limitation during their integration in TES systems. Therefore, the encapsulation of PCMs is attracting research interest to extend usage of PCMs in real TES applications in recent years. In this study, hydroxystearic acid (HSA) was encapsulated with polymethyl methacrylate (PMMA) and different PMMA comonomer shells via emulsion polymerization method for the first time in literature. HSA with high melting temperature range (74–78°C) can widen the scope of using PCMs, and the encapsulated form can make it more versatile. The chemical structures, morphologies, and thermophysical properties of capsules were determined by FT‐IR, SEM, DSC, TGA, and thermal infrared camera. Among the produced HSA capsule candidates, PMMA‐HEMA is the most promising with latent heat of 48.5 J/g with melting range of 47 to 85°C. SEM analysis indicated that the capsules have spherical shape with compact surface at nano‐micro (100–440 nm) size range; however, some capsules exhibited agglomeration.