Developments in geothermal energy in Mexico—Part thirty-seven. Procedure to diagnose production abatement problems in geothermal wells

A procedure to diagnose cases of production decrease in geothermal wells is presented. Most commonly, a production decrease in geothermal wells is due to: surface pipeline scaling, mechanical damage in the wellbore, entrance of cooler fluids to the producing reservoir layer and reservoir and well pipeline scaling. The procedure, which is presented as a decision diagram, is based in chemical and well production data. It is able to identify the above mentioned causes for a given well. This procedure was successfully applied to 17 wells from the Cerro Prieto geothermal field. In addition, a silica deposition rate parameter, Rd, was designed. It can be used as a forecasting tool for well scaling. It is proposed that this parameter is important in deriving suitable production strategies to minimise the effect of silica scaling processes in the reservoir.     

Assessment of the origin and geothermal potential of the thermal waters by hydro-isotope geochemistry: Eskisehir province,Turkey

The thermal fluids vented over Eskisehir province have been investigated for their origin and to estimate the geothermal potential of the area. Thermal waters as well as bubbling and dissolved gases were collected and analysed for their chemical and isotopic features. Their isotopic composition varies in the range from ?11.5 to ?7.7?‰ for δ¹⁸O, ?84 and ?57?‰ for δ²H, and 0–7.2 TU for tritium. The gases (bubbling and dissolved) are mostly N₂-dominated with a significant amount of CO₂. The helium isotopic ratios are in the range of 0.2–0.66?R/Rac, indicate remarkable mantle-He contribution ranging between 2 and 10?% in the whole study area. Considering the estimated geothermal gradient about three times higher than the normal gradient, and the reservoir temperatures estimated to be between 50 and 100?°C using quartz and chalcedony geothermometers, a circulation model was built where possible mixing with shallow waters cool down the uprising geothermal fluids.     

表面效应对γ-Fe2O3微粉饱和磁化强度的影响

我们制备了直径为80—700A的γ-Fe₂O₃微粉,测量了它的比饱和磁化强度σ_s和比表面积S_a,得出经验公式:σ_s(s=σ_s(∞)(1—aS_a)。假定微粉由两部分组成:第一部分是表面层,在磁场的作用下,它的磁矩只能转到与磁场成某个角度;第二部分是内部,它的磁矩可以转到磁场的方向。从这个简单的模型出发,上述的经验公式可以得到较好的解释。 关键词：     

Ra in geothermal and bottled mineral waters of Hungary

Geothermal waters have been used on a large scale for bathing, drinking and medical purposes, while the consumption of bottled mineral waters is increasing. In this work, radon and radium activity concentrations of thermal and bottled mineral waters, originating from different regions of Hungary, were studied by different radioanalytical methods. It was found that the thermal springs, which supply the world famous baths of Budapest along the right riverside of the Danube, have high ²²²Rn and ²²⁶Ra activity concentration: up to about 100 and 1 kBqm⁻³, respectively. The radium content of some investigated geothermal waters found in the NE region of the Great Hungarian Plain is even higher: up to several kBqm⁻³. The ²²⁶Ra content of bottled mineral waters, commercially available in Hungary, was determined by gamma-spectrometric method, applying radiochemical separation. The highest value exceeded 2 kBqm⁻³ in the case of the Apenta mineral water, which is a popular brand in Hungary, as well as in Europe and North America.     

A two-component model for the electron distribution function in ahigh-current pseudospark or back-lighted thyratron

Temperature, energy, and densities of two electron distribution function components, including an isotropic bulk part and an anisotropic beam, are analyzed for a hydrogen pseudospark and/or back-lighted thyratron switch plasma with a peak electron density of 1-3×10¹⁵ cm^-3 and peak current density of ≈10⁴ A/cm². Estimates of a very small cathode-fall width during the conduction phase and high electric field strengths lead to the injection of an electron beam with energies ⩾100 eV and density of 10¹³-10¹⁴ cm^-3 into a Maxwellian bulk plasma. Collisional and radiative processes of monoenergetic beam electrons, bulk plasma electrons and ions, and atomic hydrogen are modeled by a set of rate equations, and line intensity ratios are compared with measurements. Under these high-current conditions, for an initial density n_H2=10¹⁶ cm^-3 and electron temperature of 0.8-1 eV, the estimated beam density is ≈10¹³ -10¹⁴ cm^-3. These results suggest the possibility of producing in a simple way a very high-density electron beam     

Exotic Hadrons and Underlying Z2,3 Symmetries

The recent observation of higher quark combinations, tetraquarks and pentaquarks, is a strong indication of more exotic hadrons. Using Z₂ and Z₃ symmetries and standard model data, a general quark combination producing new hadronic states is proposed in terms of polygon geometries according to the Dynkin diagrams of  _n affine Lie algebras. It has been shown that Z_2,3 invariance is crucial in the determination of the mesonic or the baryonic nature of these states. The hexagonal geometry is considered in some details producing both mesonic and baryonic states. A general class of this family is also presented.     

Developments in geothermal energy in Mexico—part eighteen. History of the exploration of the cerro prieto geothermal field

Exploration of the geothermal field of Cerro Prieto started in the 1960's, including the drilling of wells at depths from 1000 m down to 1300 m, which discharged a large amount of geothermal fluid at high pressure. A simple model of the field indicated a suitable productive area of less than 1 km². More wells were drilled in the 1970's, resulting in an expected suitable productive area of 4 km². In 1986, the known suitable productive area was 25 km². The potential of the field was 1000 MW of power, which ensured the continuous production of the 620 MW already installed [1]. Currently, deep drilling is progressing on the eastern parts of the field, including wells 450 m deep which will eventually lead to a better knowledge of the extent and potential of the field through pressure, temperature and production measurements obtained from exploration wells.     

Nonlinear microwave emission in Ba0.6K0.4BiO3 crystals near Tc

We report a detailed investigation of harmonic generation at microwave frequencies in Ba_0.6K_0.4BiO₃ crystals. Second- and third-harmonic signals are investigated as a function of temperature, external magnetic field and input power level, at temperatures close to T_c. The experimental data are discussed in the framework of a phenomenological theory, based on the two-fluid model, which assumes that the microwave and the static fields, penetrating the sample within the penetration depth, perturb the partial concentrations of the normal and condensate fluids. We show that the enhanced nonlinear effects detected near T_c in Ba_0.6K_0.4BiO₃ and YBa₂Cu₃O₇ crystals may have the same origin. However, in order to account for the experimental data of Ba_0.6K_0.4BiO₃, one needs to involve a distribution of T_c over the crystal.     

Cold-cathode, glow-discharge, electron-beam gun pumped short pulse CO2 lasers

A pulsed cold-cathode glow-discharge electron beam gun emitting an electron-beam of 150 keV energy and 45 cm² cross-sectional area has been used to pump a short pulse CO₂ laser. A fast discharge capacitor bank was used to help make the design simpler than that employed in liquid coaxial lines. The system developed is capable of producing a CO₂ laser pulse of 1 J for about 200 ns duration.     

共聚改性g-C3N4-N可见光催化降解RhB的研究

染料废水的排放对人类健康和生态系统构成严重威胁,光催化技术因其操作简单、绿色环保等优点在解决环境污染问题上已显示出巨大的潜力。类石墨相氮化碳（g-C₃N₄）由于成本低且具有良好的化学稳定性,被认为是光催化领域最有前景的新型光催化剂之一,但由于单一g-C₃N₄的比表面积小、可见光吸收能力低、光生电子-空穴复合率高影响了其光催化性能。以邻氨基苯甲腈和尿素为原料,通过高温共聚改性制备高催化活性的g-C₃N₄-N光催化剂,研究g-C₃N₄-N在不同pH值、g-C₃N₄-N投加量和RhB溶液浓度条件下对RhB光催化降解的影响,并结合红外光谱、XRD、BET、UV-Vis对g-C₃N₄-N光催化降解RhB的机理和染料降解路径进行解析。结果表明,经共聚改性制备的碳化氮为类石墨型纯相g-C₃N₄-N,具有稳定的光催化活性、大的比表面积和多孔结构,在初始pH值为3时,加入50 mg的g-C₃N₄-N在可见光条件下光催化降解10 mg·L-1 的RhB可达到最好的光催化降解效果,RhB在暗反应30 min内的吸附去除率可达30%左右,120 min的去除率达到97.7%。在光催化作用下,g-C₃N₄-N将吸附在光催化剂表面的罗丹明B分子通过快速N-脱乙基过程形成DER、EER和AR等大分子中间体,它们在空穴与·OH和·O-₂作用下,共轭结构裂解、开环,生成丁二酸、间苯二酚、丙酸等小分子,脱除的乙基被逐步氧化为乙二醇,这些小分子可以被转化为CO₂和H₂O。     

谱学分析在造山带硅质岩中的应用及其地质意义

南秦岭造山带旬阳盆地吕河地区发育有泥盆系硅质岩剖面,该剖面中的硅质岩以谱学特征为基础的微区特征清晰的记录了硅质岩的形成及后期演变信息。以南秦岭造山带旬阳盆地吕河硅质岩样品为对象,借助XRF、拉曼光谱、红外光谱和X射线粉晶衍射分析结果表明：该硅质岩内矿物主要为低温石英并包含极少量的碳酸盐矿物。XRD分析结果进一步证实该碳酸盐矿物为白云石。在吕河硅质岩内,SiO₂结构463 cm-1附近拉曼特征峰经高斯拟合后的峰面积和FWHM值证实发生了低温石英的重结晶作用,该过程中伴随了流体作用引发的有序度变化和石英颗粒的自身有序度变化。在重结晶过程中,石英颗粒的自身重结晶伴随了有序度随时间推移而逐渐增高。流体作用对硅质岩的改造表现为硅质岩内碳酸盐脉体的穿插,该过程还导致低温石英有序度提升,其中越靠近矿物边缘处的SiO₂结构有序度越高。造山带演化过程对硅质岩进行的改造主要体现在两个方面：一方面,构造应力破坏了岩石的连续性并为后期热液流体的运移穿插提供了空间;另一方面,后期流体作用的参与促进了石英颗粒重结晶的进程。红外光谱可以系统的识别硅质岩内矿物的结构类型,拉曼光谱分析可以揭示原位（in situ）微组构特征,XRD在硅质岩内微量杂质矿物的识别优势明显,这些谱学手段为研究硅质岩的成岩演化提供了重要示范。     

Remnant magmatic activity in the Coastal Range of East Taiwan after arc–continent collision: fission-track data and He/He ratio evidence

The magma activity of the North Luzon Arc is considered to have ceased, due to collision with the Asian continental margin, since late Miocene. New fission track dates of zircons taken from dike swarms in the central Coastal Range of East Taiwan show very young ages of 0.5 Ma. Furthermore, the high ³He/⁴He ratios (2.5 R_A; R_A is the air ratio) of hot spring gases near the same area indicate that more than 30% of a mantle-derived source component is necessary to account for the helium composition. These results suggest the existence of later remnant magmatic activity (more than 4 Ma) in the central Coastal Range. Therefore, arc magmatism may survive longer than the previously expected after collision.     

Maximally Generalized Yang-Mills Model and Dynamical Breaking of Gauge Symmetry

A maximally generalized Yang-Mills model, which contains, besides the vector part V_μ, also an axial-vector part A_μ, a scalar part S, a pseudoscalar part P, and a tensor part T_μν, is constructed and the dynamical breaking of gauge symmetry in the model is also discussed. It is shown, in terms of the Nambu-Jona-Lasinio mechanism, that the gauge symmetry breaking can be realized dynamically in the maximally generalized Yang-Mills model. The combination of the maximally generalized Yang-Mills model and the NJL mechanism provides a way to overcome the difficulties related to the Higgs field and the Higgs mechanism in the usual spontaneous symmetry breaking theory.     

BiVO4/TiO2 heterojunction with rich oxygen vacancies for enhanced electrocatalytic nitrogen reduction reaction

The large-scale production of ammonia mainly depends on the Haber–Bosch process, which will lead to the problems of high energy consumption and carbon dioxide emission. Electrochemical nitrogen fixation is considered to be an environmental friendly and sustainable process, but its efficiency largely depends on the activity and stability of the catalyst. Therefore, it is imperative to develop highefficient electrocatalysts in the field of nitrogen reduction reaction (NRR). In this paper, we developed a BiVO₄/TiO₂ nanotube (BiVO₄/TNT) heterojunction composite with rich oxygen vacancies as an electrocatalytic NRR catalyst. The heterojunction interface and oxygen vacancy of BiVO₄/TNT can be the active site of N₂ dynamic activation and proton transition. The synergistic effect of TiO₂ and BiVO₄ shortens the proton transport path and reduces the over potential of chemical reaction. BiVO₄/TNT has high ammonia yield of 8.54 μg·h⁻¹·cm⁻² and high Faraday efficiency of 7.70% in −0.8 V vs. RHE in 0.1 M Na₂SO₄ solution.     

不同磁场环境下Heisenberg XXZ自旋链中的热量子失协

本文研究了不同磁场环境下一维Heisenberg XXZ自旋链中两量子比特的热量子失协特性. 在四种不同的磁场环境下: 1) B₁=B₂=0 (无磁场); 2) B₁≠0, B₂=0 (磁场只作用于其中一个量子比特); 3) B₁=B₂ (均匀磁场); 4) B₁=-B₂ (非均匀磁场), 对分别作用在每个量子比特上的磁场B₁和B₂对其量子关联的影响作了详细的讨论, 且数值计算和比较了其量子失协和量子纠缠的异同. 结果显示: 在有限温度下, 量子失协相比于量子纠缠更普遍, 且非均匀磁场相比于均匀磁场对量子失协和量子纠缠更有用, 更有利于量子通讯和量子信息处理过程. 关键词： 量子关联 纠缠 量子失协     

以二氧化钛前驱体为基的电流变液的成分分析和机理研究

制备了二氧化钛前驱体粉体, 它具有优良的巨电流变效应, 但不含一水草酸钙的成分. 通过X射线衍射谱、扫描电子显微镜、电感耦合等离子体光谱仪和热失重-质谱联用仪等一系列实验手段, 对二氧化钛前驱体粉体进行了表征, 发现它是非晶形态的纳米粉体, 其主要成分为TiOC₂O₄·2H₂O和TiO(OH)₂. 由二氧化钛前驱体配置的电流变液具有与钛酸钙前驱体电流变液类似的温度特征, 即 当处理温度超过160℃后, 电流变液的屈服强度会逐渐降低, 至200℃后, 巨电流变效应完全消失. 通过对比分析发现, 伴随上述巨电流变效应消失过程的化学反应是TiOC₂O₄·2H₂O 在加热过程中失去了结晶水. 这些特征在所有钛酸盐系列的电流变液中均可观察到, 因此我们推断TiOC₂O₄·2H₂O是钛酸盐系列巨电流变液中的关键物质. 关键词： 电流变液 钛酸盐 极性分子     

电流变液与电-磁流变液的衍射特性

本文把电流变液装置作为反射光栅研究其衍射特性,首次提出由电场强度改变来调节光栅常数的概念.并讨论了同时外加电场与磁场的情况下,电磁流变液的衍射特性.     

电场诱导二氧化钒绝缘-金属相变的研究进展

二氧化钒(VO_2)是电子强关联体系的典型代表,其晶体结构在特定阈值的温度、电场、光照和压力等物理场作用下会发生由单斜金红石结构向四方金红石结构的可逆转变,从而引发绝缘-金属相变.其中,电场诱导VO_2绝缘-金属相变后的电导率可提高2-5个数量级,在可重构缝隙天线、太赫兹辐射以及智能电磁防护材料等领域具有广阔的应用前景,成为近年来人们的研究热点.首先,简要概述了VO_2发生绝缘-金属相变时晶体结构和能带结构的变化,进而从电场诱导VO_2绝缘-金属相变的研究方法、响应时间、临界阈值场强调控以及相变机理几个方面系统总结和评述了近年来国内外学者在该领域的重要发现和研究进展.最后,指出了当前VO_2绝缘-金属相变研究存在的问题,并展望了未来的发展方向.     

一种可用于极化~3He实验的新型磁场系统

原子核自旋极化的~3He气体已被深入研究并广泛用于各种科学实验.在过去的极化~3He实验中,为了减小磁场梯度对纵向弛豫时间的影响,通常会建造大尺寸的亥姆霍兹线圈来提供所需均匀度的主磁场环境.本文通过计算得到了新的六正方形线圈系统,可以为极化~3He实验提供小型高均匀性的磁场装置.其中线圈系√统内部超过30%的区域磁场梯度满足(|▽B_x|~2+|▽B_y|~2)/B_0 10~(-4)cm~(-1),这一均匀区域比例超过了现在所有用于极化~3He实验的线圈装置.对于其他需要大均匀区域磁场环境的研究实验,新的六线圈系统也具有很好的应用价值.     

混合表面等离子体激元的纳米激光器设计

为了实现纳米激光器的性能优化,设计了一种基于纳米线、半圆形氟化镁、三角形空气槽和金属脊结构的纳米激光器模型。模型中耦合在低折射率电介质层中的SPP模式和纳米线波导可以在低折射率间隙下像电容器那样存储光能,从而使低折射率的空气槽场强明显增大。应用有限元法在COMSOL Multiphysics软件下,分析了该纳米激光器模型的电场分布、模式特性、品质因数和增益阈值随着设计结构几何参数变化的规律,通过各部分折线图的综合分析来得出模型性能的数据。分析表明：该模型的光场约束能力较强且传播损耗较低,其中归一化面积最小可达到0.004 8,有效传输损耗最小可达到0.002。波导模场区域和限制因素表明,该激光器模型可以实现输出光场的亚波长约束。该模型基本实现了低增益阈值、低传输损耗和高品质因数的要求。