熔模铸件砂眼缺陷分析

阐述了熔模铸造铸件出现砂眼缺陷的特征与出现的部位,分析了砂眼缺陷产生的内、外部原因并提出了相应的对策。结果表明,砂眼是由于型壳内、外部的型砂和/或耐火材料进入型腔形成的,尽量减少影响型壳质量的人为因素,提高型壳质量是防止铸件砂眼最有效的措施。     

下沟煤矿本煤层预抽钻孔合理封孔长度研究

封孔长度的合理性对于煤层预抽钻孔的抽采质量影响较大，当封孔长度较大时，不利于封孔段瓦斯的抽采，同时封孔成本增加，反之当封孔段长度较小时，若未封孔部分与煤壁裂隙导通，钻孔发生漏气又影响钻孔抽采质量。为确定合理的封孔长度，针对下沟煤矿302工作面特定的地质条件，采用单孔声波发射对巷道卸压区和应力集中区范围进行了研究，通过分析卸压区范围，确定了合理的封孔长度，并结合试验孔周边的预抽钻孔抽采数据，进行了验证分析，得出该工作面的合理封孔深度为8 m。     

双面板非金属孔内渗油研究

双面板非金属孔内渗油是PCB感光阻焊制程中最常见的品质缺陷之一。就双面板非金属孔内渗油的品质问题进行了研究,设计试验对各影响因素进行分析,确定双面板非金属孔内渗油的根本原因及改善方向。     

Advances in analysis of total uncertainties in a semi‐invasive residual stress measurement method

The ability to characterise residual stress distribution accurately and over different length scales, particularly deep into an engineering part, plays a significant role in assessing structural integrity. Two most commonly used techniques to measure residual stress fields deep into engineering components include neutron diffraction (ND) and deep‐hole drilling (DHD). As the measurements depend on several physical quantities, they are susceptible to error. The error or uncertainties may turn substantial and compromise the suitability of the results. Although noninvasive, the neutron diffraction technique is neither readily available nor portable and is limited to approximately 60‐mm‐thick specimen; errors associated with results become unacceptable at greater flight paths. Moreover, a mock‐up representing the engineering component is normally used in the ND technique. In contrast, the DHD technique is portable and measures residual stresses with high spatial resolution. An error propagation technique was applied to develop an error analysis procedure taking into consideration various stages of the DHD method and successfully applied to different DHD measurements. An essential feature comprising the effect of plasticity due to the creation of reference hole in the DHD procedure has not yet been taken into account in the error analysis procedure. This paper briefly describes how the uncertainties due to the creation of the initial reference hole can be determined. The effect of plasticity in the drilling procedure is quantified in this study. This error is combined with other sources of error and formulated to determine the total error. An incremental DHD technique was used to measure the complex triaxial residual stress field in an as‐welded circular disc, and the measured data were used to illustrate the total error using the error analysis method developed in the study.     

Squaraine Dyes for Photovoltaic and Biomedical Applications

Squaraine dyes (SQs) are an important class of polymethine dyes with a unique reasonable-stabilized zwitterionic structure, in which electrons are highly delocalized over the conjugated bridge. These dyes can not only be easily synthesized via a condensation, but also exhibit intense absorption and emission in the visible and near-infrared region with excellent photochemical stability, making them attractive material candidates for many photoelectric and biomedical applications. Thus, in this review, after an introduction of SQs, the recent advances of SQs in the photovoltaic field are comprehensively summarized including dye-sensitized solar cells, organic solar cells, and perovskite solar cells. Then, the important advances in the use of SQs as the biosensors, biological imaging, and photodynamic/photothermal therapy reagents in the biomedical field are also discussed. Finally, a summary and outlook will be provided with some new perspectives for the future design of SQs.     

分段中深孔采矿法切割槽及底部出矿结构设计优化

间柱采场用分段中深孔嗣后充填采矿法回采，为利用中深孔爆破形成切割槽及底部桃形体出矿结构，优化切割天井位置，以溜矿口上方的桃形体作为安全隔柱，利用溜矿口空间作为底部拉槽的凿岩和装药空间；采用平行中深孔和扇形中深孔相结合的方式进行布眼，爆破形成切割槽和底部桃形体出矿结构，避免了采用人工浅孔爆破施工的安全风险,切割槽爆破到位，底部桃形体出矿结构成型良好且稳固安全，该技术已在全矿推广应用。     

Salmonella in table eggs from farm to retail – When is cooling required?

Storage time and temperature are known to be important factors in determining Salmonella growth in table eggs. It is assumed that growth of Salmonella within eggs starts when the egg yolk membrane breaks down, allowing Salmonella to enter and grow. The length of time for which the yolk membrane remains intact is time and temperature dependent.The present study addresses the question whether the current legal requirement in Germany to cool table eggs marketed 18 days after laying needs to be updated. Detailed data on the current storage and transport conditions in Germany were collected. On the basis of these data, typical combinations of temperature and time were selected. For these different time-temperature scenarios, the consequences regarding the probability of growth of Salmonella Enteritidis inside the eggs were calculated. A probabilistic model consisting of nine modules reflecting storage/transport stages from farm to retail in Germany was used to calculate whether the yolk membrane remains intact during the individual steps. Growth of Salmonella was simulated without cooling (room temperature) as well as with two different cooling scenarios (4–6 °C and 8–12 °C), which are temperature ranges used in Germany by various retailers. Simulations of these scenarios resulted in relative low numbers of eggs with Salmonella growth until purchase (89 out of 50,000 eggs in the uncooled scenario, 10 out of 50,000 eggs stored at 8–12 °C and 5 out of 50,000 eggs stored at 4–6 °C). These results show that for an average egg trading time of 7.5 days, as was observed for Germany, the probability for the consumer to purchase eggs where no Salmonella growth has started and yolk membrane integrity still exists is high. However, the model supports the necessity for egg cooling after the yolk membrane integrity time is exhausted. Furthermore, the model shows clearly that cooling will extend the time period before the egg yolk membrane breaks down. According to our results, the requirement to cool eggs from the 18th day onwards after laying, as required by legislation in Germany, is reasonable, as it matches the time point of the yolk membrane breakdown for the average egg kept at 18–20 °C. Therefore, continuation of this regulation is strongly supported.     

Automated coronal hole segmentation from Solar EUV Images using the watershed transform

Region of interest segmentation in solar images is the subject of frequent research in solar physics. This study outlines watershed by immersion segmentation to identify coronal hole areas in solar images acquired using the Extreme UV Imaging Telescope (EIT). Solutions presented here produce highly accurate segmentation results of coronal holes of irregular shape, and what is more, they do so for images representing varied solar activity, recorded in different years and months. In addition, the solutions presented here make all the methods used operate very quickly. These methods include: the preprocessing step before the watershed segmentation, the watershed segmentation itself, and also the postprocessing of solar images after the watershed segmentation. The mean duration of the entire segmentation process of solar images amounts to 342 ms for a single coronal hole, without the parallel implementation of the methods used. The experiments were carried out on a computer with an Intel Core i7 CPU @ 2 GHz and 4 GB RAM. After the seed point is identified inside the coronal hole, the segmentation runs automatically.     

Investigation by neutron diffraction of texture induced by the cooling process of zirconia refractories

New fused cast refractories with a high content of zirconia have been developed to face corrosion in glass furnaces. The controlled cooling process is responsible for thermal gradients. So, thermal mismatches appear between core and edge zones of blocks. Besides, the multiphasic nature of ZrO₂ based refractories is associated to thermal mismatches during cooling. Finally, the expansive transformation of ZrO₂ can lead to stress generation.This paper is an application of neutron diffraction to study texture generated during the cooling process of zirconia based materials. In fact, it is shown that ZrO₂ crystallographic variants have particular crystallographic texture regarding the main direction of the thermal gradient in the block. It was hypothesized that a selection of crystallographic variants could be done depending on the field stress. Tensile-compressive tests at high temperature have been done, to reproduce stress environment during the transformation of zirconia.     

硅砖熔洞的成因

通过硅砖熔洞、铁斑在硅砖检验中的重要性的阐述,对生产过程中出现的一些硅砖熔洞进行原因排查,探讨了硅砖铁洞、钙洞的成因及应采取的预防措施。