Interplay of laser power and pore characteristics in selective laser melting of ZK60 magnesium alloys:A study based on in-situ monitoring and image analysis

This study offers significant insights into the multi-physics phenomena of the SLM process and the subsequent porosity characteristics of ZK60 Magnesium(Mg)alloys.High-speed in-situ monitoring was employed to visualise process signals in real-time,elucidating the dynamics of melt pools and vapour plumes under varying laser power conditions specifically between 40 W and 60 W.Detailed morphological analysis was performed using Scanning-Electron Microscopy(SEM),demonstrating a critical correlation between laser power and pore formation.Lower laser power led to increased pore coverage,whereas a denser structure was observed at higher laser power.This laser power influence on porosity was further confirmed via Optical Microscopy(OM)conducted on both top and cross-sectional surfaces of the samples.An increase in laser power resulted in a decrease in pore coverage and pore size,potentially leading to a denser printed part of Mg alloy.X-ray Computed Tomography(XCT)augmented these findings by providing a 3D volumetric representation of the sample internal structure,revealing an inverse relationship between laser power and overall pore volume.Lower laser power appeared to favour the formation of interconnected pores,while a reduction in interconnected pores and an increase in isolated pores were observed at higher power.The interplay between melt pool size,vapour plume effects,and laser power was found to significantly influence the resulting porosity,indicating a need for effective management of these factors to optimise the SLM process of Mg alloys.

Technical development of operational in-situ marine monitoring and research on its key generic technologies in China

In China,operational in-situ marine monitoring is the primary means of directly obtaining hydrological,meteorological,and oceanographic environmental parameters across sea areas,and it is essential for applications such as forecast of marine environment,prevention and mitigation of disaster,exploitation of marine resources,marine environmental protection,and management of transportation safety.In this paper,we summarise the composition,development courses,and present operational status of three systems of operational in-situ marine monitoring,namely coastal marine automated network station,ocean data buoy and voluntary observing ship measuring and reporting system.Additionally,we discuss the technical development in these in-situ systems and achievements in the key generic technologies along with future development trends.

A Self-Referenced Fiber-Optic Refractive Index Sensor for Cure Monitoring of Epoxy Composites

A self referenced fiber optic refractive index sensor is developed to measure quantitative cure extent of epoxy. In case the sensor is applied to in situ cure monitoring of epoxy composites, each sensor embedded in different location within the structure is self referenced and can be normalized to a common scale. Therefore, the real time comparative of each sensor’s output becomes possible and variations in the extent of cure at different locations can be monitored. The developed sensor was used to monitor the isothermal cure of an epoxy system. The output of the sensor was compared with the results of the differential scanning calorimetry (DSC). The self referencing function of the sensor is confirmed.

Influences of rainfall infiltration on stability of accumulation slope by in-situ monitoring test

In order to improve the understanding of the fundamental mechanism of rainfall infiltration induced landslides in accumulation slope and to clarify some important characteristics of slope performance,artificial rainfall simulation tests and field synthetic monitoring were carried out on a typical accumulation slope of Shangrui Freeway in Guizhou Province,China.The monitoring results show that the most accumulation landslides caused by rainfall infiltration are shallow relaxation failure,whose deformation zone lies within the top 0-4 m soil layer.The deformation of slope gradually reduces from the surface,where the greatest deformation lies in,to the deep part of slope.The average percentage of infiltration during the first 2 h is 86%,and then it reduces gradually with time because of the increase of the surface runoff.The average percentage of infiltration drop to a relatively stable value(50%)after 6 h.Rainfall infiltration causes obvious increase of pore-water pressure,which may result in a reduction of shear strength due to a decrease in effective stress and wetting-induced softening.The double-effect of rainfall infiltration is the main reason of rainfall infiltration induced landslides in accumulation slope.

Piezomagnetic In-situ Stress Monitoring and its Application in the Longmenshan Fault Zone

The relative change of in-situ stress is an inevitable outcome of differential movement among the crust plates. Conversely, changes of in-situ stress can also lead to deformation and instability of crustal rock mass, trigger activity of faults, and induce earthquakes. Hence, monitoring real-time change of in-situ stress is of great significance. Piezomagnetic in-situ stress monitoring has good and longtime applications in large engineering constructions and geoscience study fields in China. In this paper, the new piezomagnetic in-situ stress monitoring system is introduced and it not only has overall improvements in measuring cell＇s structure and property, stressing and orienting way, but also enhances integration and intelligence of control and data transmission system, in general, which greatly promotes installing efficiency of measuring probe and quality of monitoring data. This paper also discusses the responses of new piezomagnetic system in large earthquake events of in-situ stress monitoring station at Qiaoqi of Baoxing and Wenxian of Gansu. The monitoring data reflect adjustments and changes of tectonic stress field at the southwestern segment of and the northern area near the Longmenshan fault zone, which shows that the new system has a good performance and application prospect in the geoscience field. Data of the Qiaoqi stress-monitoring station manifest that the Lushan Earthquake did not release stress of the southwestern segment of the Longmenshan fault zone adequately and there still probably exists seismic risk in this region in the future. Combined with absolute in-situ stress measurement, carrying out long-term in-situ stress monitoring in typical tectonic position of important regions is of great importance for researchers to assess and study regional crust stability.

Design and feasibility analysis of a new completion monitoring technical scheme for natural gas hydrate production tests

As a prerequisite and a guarantee for safe and efficient natural gas hydrates(NGHs)exploitation,it is imperative to effectively determine the mechanical properties of NGHs reservoirs and clarify the law of the change in the mechanical properties with the dissociation of NGHs during NGHs production tests by depressurization.Based on the development of Japan’s two offshore NGHs production tests in vertical wells,this study innovatively proposed a new subsea communication technology-accurate directional connection using a wet-mate connector.This helps to overcome the technical barrier to the communication between the upper and lower completion of offshore wells.Using this new communication technology,this study explored and designed a mechanical monitoring scheme for lower completion(sand screens).This scheme can be used to monitor the tensile stress and radial compressive stress of sand screens caused by NGHs reservoirs in real time,thus promoting the technical development for the rapid assessment and real-time feedback of the in-situ mechanical response of NGHs reservoirs during offshore NGHs production tests by depressurization.

Experimental Study of Monitoring and Controlling of Composite Cure Process in Autoclave Featured with Fiber Optic Sensor

With the aid of the latest fiber optic sensing technology parameters in the cure process of ther- mosetting resin-matrix composite, such as temperature, viscosity,void and residual stress, can be monitored entirely and efficiently.In this paper, experiment results of viscosity measurement in composite cure process in autoclave using fiber optic sensors are presented. Based on the sensed information, a computer program is utilized to control the cure process. With this technology, the cure process becomes more apparent and controllable, which will greatly improve the cured products and reduce the cost.

Non-contact and full-field online monitoring of curing temperature during the in-situ heating process based on deep learning

Online monitoring of the curing temperature field is essential to improving the quality and efficiency of the manufacturing process of composite parts.Traditional embedded sensor-based technologies have difficulty monitoring the full temperature field or have to introduce heterogeneous items that could have an undesired impact on the part.In this paper,a non-contact,full-field monitoring method based on deep learning that predicts the internal temperature field of composite parts in real time using surface temperature measurements of auxiliary materials is proposed.Using the proposed method,an average temperature monitoring accuracy of 97%is achieved in various heating patterns.In addition,this method also demonstrates satisfying feasibility when a stronger thermal barrier covers the part.This method was experimentally validated during the self-resistance electric heating process,in which the monitoring accuracy reached 93.1%.This method can potentially be applied to automated manufacturing and process control in the composites industry.

In-situ monitoring plume,spattering behavior and revealing their relationship with melt flow in laser powder bed fusion of nickel-based superalloy

Laser powder bed fusion(LPBF)is a highly dynamic and complex physical process,and single-track de-fects tend to accumulate into non-negligible internal defects of parts.The nickel-based superalloy single track was fabricated by LPBF,and its plume and spattering behavior were monitored in situ and recorded in real time based on image recognition and tracking in this study.The relationship among laser energy density,melt flow,plume and spattering behavior during LPBF was discussed.Volumetric energy density had limitations as a design parameter for LPBF.However,we found that plume and spattering behavior can be used as real-time design parameters for the processing of LPBF parts and implemented the initial velocity statistics for LPBF single-track spattering based on the centroid extraction algorithm.The influ-ence of melt flow evolution paths on the spattering and plume behavior in three different melting modes was revealed,and a shift in plume behavior was found in the overlap region of the additive substrate.This study provides a new method for obtaining statistics of spattering-related physical quantities in the melting mode,which is beneficial for the development of processing methods to mitigate the instability of the LPBF process.

Applied research of correspondence analysis method in waste tailings reservoir heavy metal pollution monitoring points optimization

In order to optimize monitoring points and monitoring factor, the relationshipbetween pollutants and soil sample were established by correspondence analysis.Thestudy results show that the reflecting monitoring points and monitoring factors in thegraphic on the same factor axis can clearly express the intrinsic link between pollutantsand monitoring points and distribution characteristics.To determine the main monitoringpoint and the main monitoring indicators can reduce and optimize the number of monitoringpoints under the premise of ensuring the typical and representative of monitoring data.Using the correlation of pollutants can reduce the number of monitoring indicators and improvethe effectiveness of data collection.

Monitoring the Morphology of the Bottom of Streams and Reservoirs Using Electrical Impedance Spectrometry Method

A part of the Earth＇s surface has been formed by the action of running water during geomorphological development. The flow of water is one of the ways of how particles can be eroded, transported and accumulated. If endogenous processes do not work, the surface of the continents would lower to the level close to the ocean surface and the relief would have almost no ruggedness. Recently, there have been talks about the relative classification of deviation of the present state from the ＂original＂ or ＂natural＂ one caused by anthropogeneous effects. The activity of man can manifest itself by pollution, the excessive use of water, a change in the flow regime, and the like. Research into the morphology of the river bottom and the bottom of settling tanks or dam reservoirs is systematically carried out in selected streams and reservoirs by the long-term sampling of bottom sediments. The knowledge of the sediment layer is also important. The EIS method, which was used for measuring, is new for the aforementioned applications. Possibilities of EIS method with new apparatus using for this application were tested in laboratory and in situ. On the basis of interpretation of the electrical conductivity data, a grid of depth data was acquired. These data are characterized by anomalously high and low ＂spots＂ and show morphological changes in the studied area.

超声在线监测不饱和聚酯树脂固化过程及其动力学行为

为探索不饱和聚酯树脂(UPR)固化体系在不同温度下的超声振幅变化规律,采用超声波穿透技术对UPR固化过程进行在线监测,获得声速、储能模量、松弛时间、凝胶时间等动力学参数变化规律,并得到固化反应动力学方程。结果表明:温度越高,声速与储能模量变化越快,且最终数值也越大,而固化松弛时间与凝胶时间随温度增加而缩短;此外,超声法与差示扫描量热法(DSC)得到的固化度曲线变化高度一致,通过2种方法所得到的反应活化能分别为38.14 kJ/mol和45.3 kJ/mol;最终,通过DSC法确定了UPR固化反应动力学级数为0.92。总之,超声法与DSC法2种方法相互结合,不仅证明了超声结果的准确性,也为UPR固化过程提供一种精准的在线监控技术和量化方法,从而为UPR生产过程提供理论指导。

In-situ measurement and distribution of flue gas mercury for a utility PC boiler system

The in-situ instrumentation technique for measuring mercury and itsspeciation downstream a utility 100 MW pulverized coal (PC) fired boiler system was developed andconducted by the use of the Ontario hydro method (OHM) consistent with American standard test methodtogether with the semi-continuous emissions monitoring (SCEM) system as well as a mobile laboratoryfor mercury monitoring. The mercury and its speciation concentrations including participate mercuryat three locations of before air preheater, before electrostatic precipitator (ESP) and after ESPwere measured using the OHM and SCEM methods under normal operation conditions of the boiler systemas a result of firing a bituminous coal. The vapor-phase total mercury Hg(VT) concentration declinedwith the decrease of flue gas temperature because of mercury species transformation from oxidizedmercury to particulate mercury as the flue gas moved downstream from the air preheater to the ESPand after the ESP. A good agreement for Hg°, Hg^(2+) and Hg( VT) was obtained between the twomethods in the ash-free area. But in the dense particle-laden flue gas area, there appeared to be abig bias for mercury speciation owing to dust cake formed in the filter of OHM sampling probe. Theparticulateaffinity to the flue gas mercury and the impacts of sampling condition to accuracy ofmeasure were discussed.

固化封尘剂智能加药在线监测系统的设计

传统的封尘剂管理和监测方法存在诸多局限性和问题,开发了一种固化封尘剂智能加药在线监测系统,介绍了该系统的设计、搭建、测试及结果。测试结果表明,该系统可以有效地监测固化封尘剂的加药量,并能根据生产需求自动调整药剂投放量,提高煤场物料密度和装载效率,减少煤炭流失,保护周边环境。

基于光纤光栅监测固化工艺参数对层合板内部残余应变的影响

复合材料以其比强度、比模量高,具有较好设计性等优点,成为轻量化装备的重要材料。复合材料生产过程中产生的残余应变是制约其快速发展和应用的重要因素之一,因此研究成形过程中材料内部应变变化十分必要。本文采用内埋光纤布拉格光栅(Fiber Bragg grating,FBG)的方法,对T700/C11预浸料在不同工艺参数下成形时内部应变及温度进行实时监测,探究了工艺条件对其内部应变的影响,建立了预测层合板残余应变数值分析模型,从而优化复合材料固化工艺参数。结果表明,合理地降低升温速率、使用较低热膨胀系数和导热系数的模具材料以及避免铺放误差可以有效降低残余应变。

基于物联网的密集烤房精准监测平台设计

该研究以窄带物联网(NB-IoT)为基础构建密集烤房环境参数精准自动监测平台,采用主控制器、电源模块和传感器模块组成的设备,实现对烟叶烘烤过程中装烟室内不同区域环境参数的全方位、全流程的精准自动监测,同时通过NB-IoT模块实现监测系统和云平台的连接,使“云计算”和烟叶烘烤结合,提高烘烤温湿度自动监测与控制的精度,降低劳动强度,为实现密集烤房烟叶烘烤的数字化、智慧化调控奠定坚实基础。

In situ and on-line monitoring of cadmium in soil pore water using an automatic sampling integrated electrochemical sensor

Cadmium(Cd) contamination in soil pore water is the primary pathway for Cd uptake by food crops,such as rice(Oryza sativa L.),posing significant risks to both food safety and human health.This study presents a novel soil pore water metal sensor(SPW-Msensor) for in situ and online monitoring of Cd in soil pore water(Cd_(pw)).The SPW-Msensor integrates an automated sampling device,comprising a Rhizon sampler and a reciprocating series pump with an independent dual plunger drive,along with a portable electrochemical sensor consisting of a screen-printed electrode,flow cell,and portable potentiostat.The SPW-Msensor enables the detection of Cd within a linear range of 50 to 300 ppb while exhibiting high anti-interference capability.Moreover,it demonstrates excellent repeatability(relative standard deviation values(RSDs)<3.6%) across 30 measurements conducted within a 2-h period.The method exhibits good agreement with results obtained using the standard ICP-MS method(RSDs<5%).Additionally,this study establishes a positive correlation between Cd_(pw)detected by the SPW-Msensor and total Cd concentration(Cd_(total)) in the soil with an R^(2) value equal to 0.89.Data acquired from the SPW-Msensor can be utilized for predicting Cd_(total)through partial least squares regression modeling,achieving model quality score(Q^(2)) of 0.69,adjusted R^(2) of 0.9345,and root mean square error(RMSE) of 0.1912.The SPW-Msensor demonstrates real-time monitoring capabilities for assessing Cd levels in acidified soils.This SPW-Msensor offers an efficient approach for in-situ and continuous monitoring of Cd_(pw)that provides valuable insights applicable to environmental and agricultural domains.

松材线虫病监测普查与防治技术

为了有效控制松材线虫病疫情的发生,对松材线虫病监测普查与防治技术进行了探讨。提出应根据松材线虫病的发病特点,先从监测范围、监测时段、监测的内容、监测方法等方面制定监测普查方案,再从取样方法、分离鉴定等方面确认疫情和疫情详查,最后根据疫情情况从检疫检验、物理防治、化学防治、生物防治4方面进行防治,从根本上控制松材线虫病的扩散。

Research and implementation of the monitor for in situ radioactivity measurements in the marine environment

As the traditional methods can not meet the requirements of marine radioactivity monitoring,a radioactivity monitoring sensor used in marine field has been proposed.This sensor is based on Nal(TI) scintillation crystal and employs the special shielding method,the anticoincidence design,the spectrum stabilization algorithm of characteristic peaks and the Monte Carlo simulation fitting calibration formula.Through the continuous tests of terminals and the activity test for target nuclide ^(40)K,it is found that the sensor is stable and the error is less than 10%.

基于治未病理念探讨中西医联合防治溃疡性结肠炎

溃疡性结肠炎是一种病因不明的肠道炎症,病情反复缠绵,具有一定的癌变倾向,很难完全治愈,对该病早期防治尤为重要。本研究基于“治未病”思想,从未病先防、既病防变、病后防复三个方面探讨中西医联合防治溃疡性结肠炎,以期为临床治疗该病提供理论依据。