基于TS-SVM模型的水安全评价

核函数参数和误差惩罚因子的选择对支持向量机模型(SVM)的精度有较大影响。为充分发挥SVM的性能,提出基于禁忌搜索算法优化的支持向量机模型(TS-SVM)。将TS-SVM应用于山东省水安全指数计算,得到各个水安全利用方案的评价指数值和安全等级。对比分析表明,TS-SVM具有较强的学习能力,能给出合理的评价结果,是一种有效的评价模型。     

推进水价改革 促进水资源高效利用

针对目前国内水资源和供水现状情况,提出几点相应建议:首先是培育和发展水市场,正规水市场的建立对于推进水价改革和水价经济杠杆作用的发挥十分重要,引入私有企业可以加强竞争,提高供水企业运行效率;其次是不同用户类型采用不同的水价形式;最后是加强节水宣传,提高水价改革的执行力。     

基于期权思想的融资租赁在水电工程中的应用浅析

针对当前水电项目融资模式单一,前期负债重的问题,提出了一种基于期权思想的适用于水电工程机电设备融资的租赁方式。这种融资方式将期权思想融入到厂商租赁模式当中,可以使承租方建设期及生产期前期不必支付租金,而在效益稳定,其他还款压力较小时开始支付租金;对出租方而言,则相当于买入一份期权合约,当电站效益上升时,出租方将会获得较高的回报。通过案例分析,结果表明:基于期权思想的融资租赁方式与其他融资方式相比,在水电工程项目中具有一定的优越性。最后对该融资方式的改进方向进行了适当阐述。     

石灰稳定土在道路工程中的应用

本文详细阐述了根据美国AASHT0 T220标准进行石灰稳定土配合比设计的两种试验方法:一种是根据土的塑性指数来确定石灰剂量;另一种是根据石灰土的pH值来确定掺加土中的最少石灰剂量。在确定加入土中的最少石灰剂量以后,还需对石灰稳定土进行无侧限抗压强度检验,保证强度满足规范要求。由于很多地区缺乏天然砂石材料,铺筑路面基层(非高等级公路)及底基层靠完全外运石料将造成工程造价太高,且石灰稳定土的刚性和分布荷载能力较传统的级配碎石高得多,因此,广泛推广石灰稳定土在路面基层(非高等级公路)及底基层中的应用,对节约工程造价,降低工程难度具有重大的现实意义。     

基于集对分析模型的岷江上游流域震后水质综合评价

汶川大地震是我国建国以来强度最大、破坏最严重的一次地震,给我国带来巨大的人员伤亡和经济损失。岷江上游流域生态环境较为脆弱,地震、泥石流、滑坡、崩塌等地质灾害经常发生,极易造成突发性水源污染。通过引入基于熵权改进的集对分析模型,对岷江上游流域映秀镇周边水源地进行综合评价,最好、平均、最差三种情况评价结果均为Ⅰ级。结果表明,"5.12"汶川特大地震对岷江上游流域部分水源地水质影响不大,震后岷江上游流域水质无明显变化。     

用于胎儿超声切面识别的知识蒸馏方法

胎儿超声切面识别是产前超声检查的主要任务之一,直接影响了产前超声检查的质量.近年来,深度神经网络方法在临床超声辅助诊断方面取得了许多进展.然而,已有研究大多应用预训练模型微调进行迁移学习,这不仅容易导致参数冗余和过拟合问题,而且限制了在实际应用中的实时分析能力.本文提出用于胎儿超声切面识别的知识蒸馏方法.第1阶段,在学...     

Processing of high-performance Co doped Y2O3 as a single-phase electrolyte for low temperature solid oxide fuel cell (LT-SOFC)

The high-performance single-phase semiconductor materials with higher ionic conductivity have drawn substantial attention in fuel cell applications. Semiconductor materials play a key role to enhance ionic conductivity subsequently promoting low temperature solid oxide fuel cell (LT-SOFC) research. Herein, we proposed a semiconductor Co doped Y₂O₃ (YCO) samples with different molar ratios, which may easily access the high ionic conductivity and electrochemical performances at low operating temperatures. The resulting fabricated fuel cell 10% Co doped Y₂O₃ (YCO-10) device exhibits high ionic conductivity of ∼0.16 S cm⁻¹ and a feasible peak power density of 856 mW cm⁻² along with 1.09 OCV at 530 °C under H₂/air conditions. The electrochemical impedance spectroscopy (EIS) reveals that YCO-10 electrolyte based SOFC device delivers the least ohmic resistance of 0.11–0.16 Ω cm² at 530-450 °C. Electrode polarization resistance of the constructed fuel cell device noticed from 0.59 Ω cm² to 0.28 Ω cm² in H₂/air environment at different elevated temperatures (450 °C to 530 °C). This work suggests that YCO-10 can be a promising alternative electrolyte, owing to its high fuel cell performance and enhanced ionic conductivity for LT-SOFC.     

Synthesis and characterization of a high near infrared reflectance yellow pigment SbxWO3 (x ≤ 0.14)

In this work, a novel yellow near-infrared (NIR) reflective pigment based on the formula of Sb_xWO₃ was developed by high temperature solid-state method at 700–900 °C. The formation of Sb_xWO₃ was confirmed by XRD analysis, and the synthesized pigments are orthorhombic phase with high near infrared reflectivity (84.69%–87.28%). The acid/alkali resistance studies reveal that the color difference ΔE * of the pigments before and after soaking was less than 5, and the as prepared pigments are chemically stable under the atrocious weather. In addition, the synthetic pigments are bright yellowish green (L* = 92.1–92.9, a* = -4.9–4.1, b* = 35.0–37.0). In the heat insulation performance test, the indoor temperature with the Sb_xWO₃ heat insulation coating is 3.1 °C lower than that without heat insulation coating. In summary, the as prepared Sb_xWO₃ pigment has the advantages of high solar reflectivity and less toxic elements, making this new environmentally friendly energy-saving yellow pigment used as a colorant for building exterior coating formulations to reduce heat accumulation and cooling energy consumption.     

Effect of polystyrene addition on properties of porous Si3N4 ceramics fabricated by digital light processing

Porous Si₃N₄ ceramics with high strength and high transmittance have been widely used in the field of defense and military. Additive manufacturing (AM) technology is one of the effective means to fabricate porous Si₃N₄ ceramics. Nevertheless, it is difficult to prepare porous Si₃N₄ ceramics by using digital light processing (DLP) because of the large refractive index difference between Si₃N₄ powders and photosensitive resin. In this study, the effects of the amount of polystyrene (PS) powders on the properties of Si₃N₄ ceramic slurries and sintered ceramics were systematically discussed. The addition of PS reduced the overall refractive index of powders and increased the average particle size of powders, thus improving the cure depth of Si₃N₄ ceramic slurries from 11.0 ± 2.0 μm to 55.7 ± 1.8 μm. With the increase of PS content, the shrinkage and porosity of Si₃N₄ ceramics gradually increased, and the bulk density and flexural strength showed the opposite trend. The slurry with low viscosity (2.38 Pa٠s at a shear rate of 30 s⁻¹) and high cure depth (51.2 ± 4.6 μm) was obtained when the content of PS was 15 wt%, which met the thickness requirements for printing. The total porosity of Si₃N₄ ceramics reached the maximum values at 28.21 ± 2.58%. The addition of PS solved the problem of low cure depth of slurries, and PS as a pore-forming agent could help Si₃N₄ ceramics form porous structure. This research provides valuable insights into the fabrication of non-oxide ceramics with high refractive index using DLP technology.     

Room temperature NH3 gas sensor based on PMMA/RGO/ZnO nanocomposite films fabricated by in-situ solution polymerization

Effective detection of ammonia gas is of great importance due to its detrimental effects on human health, environment, and ecosystem. High-performance composite gas sensors are vital in accomplishing this goal. Herein, we investigate the performance of an ammonia (NH₃) gas sensor fabricated via dip-coating the silver interdigitated electrode for PMMA/RGO/ZnO (PRZ) nanocomposite solution with acetone as a solvent. The PRZ ternary nanocomposite was synthesized using the in-situ solution polymerization method and the resistive properties of the films assembled on the interdigitated electrode were analyzed, with respect to the fixed and varying ammonia gas concentrations, using LCR meter. When the sensor is operated in the controlled chamber containing ammonia gas at room temperature, the sensor responds rapidly to ammonia with a fast recovery of 13.02 s at a gas concentration of 350 ppm. The PRZ sensor exhibits high sensing percentage response (527%), excellent repeatability (four times), high sensitivity at low concentrations (less than 10 ppm), swift response and recovery times (1.94 s/13.02 s), and long-term stability (up to 90 days) with fluctuation of 3.2%, which signifies PRZ composite as a potential material for ammonia gas sensor. Aspects such as simplicity of the synthesis process and fabrication, excellent sensing performance, as well as fast response-recovery time at a particular gas concentration are noteworthy in this study. These features can be utilized for the detection of ammonia gas in chemical and biological fields.