Pressure transient analysis for asymmetrically fractured wells in dual-permeability organic compound reservoir of hydrogen and carbon

In this paper, a comprehensive semi-analytical model was presented to investigate pressure transient behavior for asymmetrically fractured wells in organic compound reservoir of hydrogen and carbon with dual-permeability behavior. Stehfest inversion algorithm can be used to transform it back into time domain to obtain pressure solution. The presented solution was validated well with numerical solutions. Flow characteristics for asymmetrically fractured wells in dual-permeability organic compound reservoir of hydrogen and carbon were divided into five regime. The effects of some important parameters on dimensionless pressure and its derivative curves were analyzed in details, including inter-porosity flow coefficient from matrix to natural fractures λ, storage coefficient ω, fracture asymmetry factor θ and permeability ratio κ. The presented model can be used to predict production performance and do well test analysis in the development of dual-permeability organic compound reservoir of hydrogen and carbon.     

基于模糊综合评判和层次分析法的中子管故障风险评估

中子管是一种用途广泛的关键部件，然而目前国产中子管的可靠性水平与国外相比还有一定差距，难以满足各行业的使用需求。本文分析了中子管的主要故障模式，采用模糊综合评判和层次分析法对中子管故障进行了多级模糊综合评判，并对中子管故障风险进行了评估。结果表明，中子管总体故障风险水平中等，故障风险前3位的部件为靶、氘氚储存器和加速极，在设计和使用中应重点关注靶释放氦气，靶膜氧化，氘氚储存器吸气剂局部破损，绝缘瓷管破损，加速极离子加速、聚焦不稳定等故障。     

Development of a void ratio-moisture ratio-net stress framework for the prediction of the volumetric behavior of unsaturated granular materials

Despite extensive research on the behavior of unsaturated fine-grained materials, there is still a lack of understanding of the volumetric behavior of unsaturated granular materials. In this research, a model has been developed to predict the fundamental volumetric behavior of unsaturated granular materials through loading and wetting state paths. In this regard, a loading-wetting surface was developed in a space of void ratio-moisture ratio-net stress. A distinctive feature of the proposed model is the relative simplicity in obtaining the model parameters using conventional geotechnical testing equipment. Two types of recycled granular materials, commonly applied in unbound pavements were used, namely, recycled crushed brick (CB) and excavation waste rock (WR). The uniqueness of the developed surface was evaluated by employing a number of loading and wetting state paths. The results indicate that the developed surface is unique in its loading state paths; however, it only shows uniqueness in its wetting state paths for stress levels greater than 2000 kPa. The proposed model seeks to introduce the application of the unsaturated soil mechanics theory, for predicting the behavior of granular materials in the field, by providing a practical and cost-effective methodology.     

Evaluation and validation of an automatic jaw movement recorder (RumiWatch) for ingestive and rumination behaviors of dairy cows during grazing and supplementation

Observation of ingestive and rumination behaviors of dairy cows may assist in detecting diseases, controlling reproductive status, and estimating intake. However, direct observation of cows on pasture is time consuming and can be difficult to realize. Consequently, different systems have been developed to automatically record behavioral characteristics; among them is the RumiWatch System (RWS; Itin and Hoch GmbH, Liestal, Switzerland). Until now, the RWS has not been thoroughly validated under grazing conditions. The aim of the current study was to validate the RWS, against direct observation, in measuring ingestive and rumination behaviors of dairy cows during grazing and supplementation in the barn. A further objective was to examine whether it is possible to refine the algorithm used by the evaluation software RumiWatch Converter 0.7.3.2 to improve the accuracy of the RWS. The data were collected from an experiment carried out with 18 lactating Holstein cows in a crossover block design including 3 treatments and 3 measuring periods. All cows grazed night and day, 19 h/d, and were either unsupplemented or supplemented, with chopped whole-plant corn silage, or chopped whole-plant corn silage mixed with a protein concentrate. During the measuring periods, cows were equipped with the RumiWatch Halter, and their ingestive and rumination behaviors were recorded concurrently by the RumiWatch Halter and by direct observation (690 × 10 min). Comparison of concurrently measured data shows that the RWS detected jaw movements reliably, but classification errors occurred. A low relative prediction error of ≤0.10 for the number of rumination boluses, rumination chews, and total eating chews was found. A high relative prediction error of >0.10 was found for the number of prehension bites and time spent in prehension and eating. Both converter versions performed equally well in differentiating ingestive and rumination behaviors when cows were supplemented in the barn or when grazing and supplementation activities were combined. For grazing cows, with no supplementation, more reliable results for the total number of eating chews, rumination chews, prehension bites, and time spent in these activities were obtained, by using the RumiWatch Converter 0.7.3.11. In light of these findings, further research is warranted to improve the accuracy of the RWS and to allow a differentiation between mastication chews and prehension bites while eating.     

Reliability Allocation for Series-Parallel Systems subject to Potential Propagated Failures

To analyze the dependent failures in the early stage of system development, this paper considers the potential propagated failures in the reliability allocation process. Factors which can be used to not only measure the component importance but also to reflect the influence brought by propagated failures are proposed. Specifically, cooperative game theory is introduced to explore how the propagated failures affect the failure severity level. Failure rates are obtained by using the Alpha Factor Model with the consideration of dependence among components. Reliability improvement rate is also developed to proportionally assign the target improvement of system reliability to the corresponding components. Furthermore, reliability allocation frameworks for series, parallel and series-parallel systems are designed respectively to make the proposed model meet a wide range of applications. An illustrative example of a hydraulic cooling system is presented to show how the proposed approach is applied. The allocation results demonstrate that the proposed method can achieve a valid reliability improvement with the minimum error.     

Colloidal processing of Al2O3-doped zirconia ceramics with CaO–P2O5–SiO2 glass as additive

Well-dispersed concentrated aqueous suspensions of Al₂O₃-doped Y-TZP (AY-TZP), AY-TZP with 5.4 vol% of CaO–P₂O₅–SiO₂ (CaPSi) glass (AY-TZP5) and 10.5 vol% CaPSi glass (AY-TZP10), with ammonium polyacrylate (NH₄PA) dispersant were prepared to produce slip cast compacts. The rheological properties of 35 and 40 vol% slips were studied. The densification, microstructure as well as hardness and fracture toughness were investigated as a function of CaPSi glass content at 1300°C-1500°C. The optimum NH₄PA concentration of 35 vol% AY-TZP5 and AY-TZP10 slips at pH ~9 was found to be about 43% and 67% greater than that of AY-TZP slips; this behavior was related to the greater amounts of Ca²⁺ ions leached out from the CaPSi glass surface. The viscosity of stabilized 40 vol% slips with NH₄PA attained a minimum value at 5.4 vol% CaPSi glass addition, and resulted in a more dense packing of cast samples. AY-TZP5 can be sintered at a lower temperature (1300°C) compared to that of AY-TZP. AY-TZP5 exhibited a fine microstructure of tetragonal ZrO₂ (grain sizes below 0.3 µm), and ZrSiO₄–Ca₂P₂O₇ particles homogeneously distributed within the zirconia matrix. It presented similar fracture toughness and a slightly lower hardness compared to those of AY-TZP.     

非晶Fe粉掺杂Al-12Si合金的高温压缩变形行为

为提高Al-12Si合金的热变形抗力,并探索非晶Fe粉掺杂对Al-12Si合金热压缩行为的影响和掺杂非晶Fe粉热压缩中的晶化温度等,采用连续挤压技术制备了掺杂10wt%非晶Fe粉与不掺杂非晶Fe粉的Al-12Si合金试样,对试样进行了不同温度和应变速率下的热压缩试验,分析了试样在热压缩中的组织转变,以及采用双曲正弦关系构建了试样的热流变应力方程。结果表明:非晶Fe掺杂试样在450 ℃及以下的热压缩时,Fe维持非晶态,500 ℃时,则已发生晶化;掺杂10wt%非晶Fe粉使Al-12Si合金的热抗变形能力显著提高,其热压缩激活能Q=211.29 kJ/mol,比未掺杂非晶Fe粉的Al-12Si合金试样高40.78 kJ/mol,且热压缩过程中存在动态回复和动态再结晶;利用双曲正弦关系构建试样的热流变应力方程为ε·=4.42×10¹⁴[sinh(0.016 6σ)]^6.13exp(-211 290/RT),线性回归系数高达0.99,即可为非晶Fe粉掺杂试样的热加工提供一定的理论指导。     

5%碳酸氢钠严格控制代谢性酸中毒对活体肾移植患者术后早期肾功能的影响

目的：观察使用5%碳酸氢钠严格控制代谢性酸中毒是否可改善活体肾移植患者术后早期肾功能。方法：选择2019年3月至2020年3月于中国科学技术大学附属第一医院择期行活体肾移植手术的120例尿毒症患者为研究对象，随机分为观察组和对照组。观察组术中根据碱剩余（BE）测量值补充5%碳酸氢钠，维持－3 mmol/L≤BE≤+3 mmol/L。对照组仅在明显代谢性酸中毒（BE≤－10 mmol/L或pH≤7.25）时才补充5%碳酸氢钠。调整分钟通气量，使PaCO2在正常范围内。记录患者麻醉前（T0）、麻醉诱导后10 min（T1）、肾动脉血流开放前（T2）、肾动脉血流开放后5 min（T3）、手术结束时（T4）的血流动力学指标及术中出血量、输液量、手术时间。记录术后1、2、3、7、30 d的肌酐、尿素氮及尿量。结果：与对照组相比，观察组术中5%碳酸氢钠输注量明显增加，去氧肾上腺素使用量明显减少（P<0.05），对照组无输注5%碳酸氢钠指征；观察组术毕时pH、BE明显大于对照组（P<0.05）。与T0时比较，T3时两组MAP、CVP均明显降低（P<0.05）。观察组术后1、2、3、7 d血肌酐、尿素氮含量明显低于对照组（P<0.05）。观察组术后1、2、3 d尿量明显多于对照组（P<0.05）。结论：活体肾移植术中应用5%碳酸氢钠严格控制代谢性酸中毒可改善术后早期肾功能。     

Microstructural characteristic,outward-inward growth behavior and formation mechanism of MAO ceramic coating on the surface of ADC12 Al alloy with micro-groove

The ceramic coatings on the surface of aluminum alloy substrates with micro-grooves have been successfully fabricated in the silicate solution via micro-arc oxidation (MAO) approach. Microstructure characterization showed that the larger main discharge channels were located in the center of micro-groove, the smaller secondary discharge channels were located on both sides of main discharge channel; and a few irregular micro-pores existed in the vicinity of all discharge channels, which were mainly cause by the rapid cooling and solidification of discharge channels hindering the removal of gases produced via reaction. Moreover, the growing direction of coating in the initial stage was mainly outward-growth and resulted in the formation of inverted triangle coating structure, which was due to the sharp-angled effect. But in the final growing stage, the inward-growth behavior played a key role owing to the spark transfer. According to above results and discussion, the formation of smooth, uniform and homogeneous ceramic coating on the surface of whole trapezoidal micro-groove substrate contained four stages: anodic oxidation growth, sharp corner rapid growth, coating homogenization and groove self-filling.