甲烷干气重整镍基复合结构催化剂的研究进展

甲烷干气重整反应能够实现温室气体CO₂和CH₄的转化利用, 其反应产物合成气可以通过费托反应进一步生产液态燃料, 该反应在能源与环境领域具有重要意义。寻找合适的催化剂是推动甲烷干气重整工业化的关键。镍基复合结构催化剂因其与贵金属催化剂相媲美的催化活性和低廉的工业成本而受到广泛关注, 但镍基催化剂存在高温下长时间反应后碳沉积和金属组分烧结所导致的失活问题, 严重影响了其工业应用和干气重整化工的发展。本文从镍基复合结构催化剂的成分、结构、制备方法及模拟计算设计等方面出发, 介绍了改进镍基催化剂活性、抗积碳和抗烧结性能的研究进展, 并结合最新的原子催化以及原位表征等研究进展对干气重整研究的发展趋势进行 展望。     

Multi-objective ceramic matrix composite material design using the variable fidelity model management optimization framework

The increasing computational requirements of advanced numerical tools for simulating material behaviour can prohibit direct integration of these tools in a design optimization procedure where multiple iterations are required. Therefore, a design approach is needed that can incorporate multiple simulations (multi-physics with different input variables) of varying fidelity in an iterative model management framework that can significantly reduce design cycle times. In this research, a material design tool based on a variable fidelity model management framework is applied to obtain the optimal size of a second phase, consisting of silicon carbide (SiC) fibres, in a silicon-nitride (Si₃N₄) matrix to obtain continuous fibre SiC-Si₃N₄ ceramic composites (CFCCs) with maximum high temperature strength and high temperature creep resistance. This investigation shows how models with different dimensions and input design variables can be handled and integrated efficiently by the trust region model management framework, while significantly reducing design cycle times in application to the design of multiphase composite materials.     

Suppression of phase-noise interference due to closely spaced data and calibration signals

At high frequencies, phase noise, which occurs at frequencies surrounding a data frequency, may seriously interfere with the measurement of nearby signals. Our motivation for removing phase noise was based on our use of simultaneous data and calibration signals, which were closely spaced in frequency. We found that by measuring the source phase noise, we are able to effectively remove phase-noise interference from the measured data and calibration signals. In order to accomplish this phase-noise suppression, a normalization procedure has been developed so that signals on differing measurement channels can be compared. Using this phase-noise suppression procedure and a prototype measurement system, we were able to improve magnitude measurements by 36 dB. We were able to improve phase measurements by a factor of 70. We propose that this procedure can significantly improve measurement accuracy in many situations where two closely spaced signals, which have a common source, must be measured with high accuracy. This procedure can also be used to monitor, and thereby remove, other types of interference besides just phase noise.     

Auto-consistent environment for measurement software development

In a measurement environment, the user will repeatedly change some of the measurement settings and will want to view the results. Developers of elaborate measurement systems are often puzzled as to whether the generated results correspond to the latest settings. Data consistency in a measurement system means that displayed results will always conform to the latest settings. This paper suggests that automatic data consistency is an underestimated feature of dataflow environments. If only a few of the settings are modified each time, it is unreasonable to repeat operations that do not depend on the changed settings. A demand-driven execution scheme is presented in which data tokens are tagged with their time of calculation. This scheme avoids redundant operations without programmer intervention. This is an important concern when some real-time constraints are to be met, because the operations in complex measurement systems can be very time-consuming. When the developer must handle these two issues programmatically, their combination often results in unmanageable programs     

一种用于线膨胀系数测量的高稳定性激光干涉系统

介绍了一种可以对材料长度变化进行测量的高稳定性双光程激光干涉系统,由于该干涉系统的测量光路和参考光路具有相似的传播路径,光程差仅由被测试样的长度引起,干涉系统具有较强的抵抗环境温度变化和振动等外界干扰的能力。通过平晶反射膜测量试验,对干涉系统的稳定性进行了验证,结果表明在6. 5 h内测量数据的标准偏差为4. 2 nm。该激光干涉系统可用于材料尺寸变化(如线膨胀系数)的高准确度测量。     

有机氟聚合物加固保护砂岩文物的可行性

报道了用有机氟聚合物渗透加固保护砂岩文物的研究，目的是提高文物的机械强度，阻止或减缓水的侵蚀。分别进行了渗透深度、抗压强度、持水量、冻融等实验，以评估加固保护效果及有机氟聚合物在砂石文物保护应用的可行性。结果表明，有机氟聚合物在砂石类文物的加固保护中具有良好效果。     

Uncertainty Evaluation and Validation of a Comparison Methodology to Perform In-house Calibration of Platinum Resistance Thermometers using a Monte Carlo Method

The uncertainty required by laboratories and industry for temperature measurements based on the practical use of platinum resistance thermometers (PRTs) can commonly be achieved by calibration using temperature reference conditions and comparison methodologies (TCM) instead of the more accurate primary fixed-point (ITS-90) method. TCM is suitable for establishing internal traceability chains, such as connecting reference standards to transfer and working standards. The data resulting from the calibration method can be treated in a similar way to that prescribed for the ITS-90 interpolation procedure, to determine the calibration coefficients. When applying this approach, two major tasks are performed: (i) the evaluation of the uncertainty associated with the estimate of temperature (a requirement shared by the ITS-90 method), based on knowledge of the uncertainties associated with the temperature fixed points and the measured electrical resistances, and (ii) the validation of this practical comparison considering that the reference data are obtained using the ITS-90 method. The conventional approach, using the GUM uncertainty framework, requires approximations with unavoidable loss of accuracy and might not provide adequate uncertainty evaluation for the methods mentioned, because the conditions for its valid use, such as the near-linearity of the mathematical model relating temperature to electrical resistance, and the near-normality of the measurand (temperature), might not apply. Moreover, there can be some difficulty in applying the GUM uncertainty framework relating to the formation of sensitivity coefficients through partial derivatives for a model that, as here, is somewhat complicated and not readily expressible in an explicit form. Alternatively, uncertainty evaluation can be carried out by a Monte Carlo method (MCM), a numerical implementation of the propagation of distributions that is free from such conditions and straightforward to apply. In this paper, (a) the use of MCM to evaluate uncertainties relating to the ITS-90 interpolation procedure, and (b) a validation procedure to perform in-house calibration of PRTs by comparison are discussed. An example illustrating (a) and (b) is presented.     

Characterization of patinas by means of microscopic techniques

Many stone-made historic buildings have a yellowish layer called 'patina' on their external surface. In some cases, it is due to the natural ageing of the stone caused by chemical–physical reactions between the surface of the stone and the environment, and in other cases it is the result of biological activity. The origin of these patinas can be also be due to ancient protective treatments. The use of organic additives, such as protein-based compounds, in lime or gypsum-based patinas is a traditional technique, which has been used in past centuries for the conservation and protection of stone materials. The thinness of the patinas ensures that microscopic techniques are irreplaceable for their analysis. Optical Microscopy, Fluorescence Microscopy, Scanning Electron Microscopy together with an Energy Dispersive X-ray Spectrometer, and Electron Microprobe are the microscopic techniques used for the characterization of these coverings, providing very useful information on their composition, texture and structure.     

The appropriateness of the systematic framework to develop diagnosis procedures of nuclear power plants—an experimental verification

It has been well recognized that a diagnosis procedure that allows operators to successfully identify the nature of an on-going event is inevitable for an effective and appropriate recovery. Unfortunately, studies for a framework that can suggest a unified and consistent process in constructing a serviceable diagnosis procedure seem to be scant. Thus, Park et al. have suggested a systematic framework that can be used to construct a useful diagnosis procedure. In addition, the diagnosis procedure that is currently in use at the reference nuclear power plant (NPP) is reformed in order to demonstrate the appropriateness of the suggested framework. However, the necessity of a well-designed experiment is proposed to confirm the appropriateness of the suggested framework.In this regard, in this study, an experiment is conducted using a full-scope simulator of the reference NPP. From the experiment, two sets of operators' diagnosis performance data are collected, and then they are compared to investigate the change of an operator's diagnosis performance with respect to two types of diagnosis procedures.As a result, it is shown that an operator's diagnosis performance is improved when the revised diagnosis procedure is used. Therefore, it is reasonable to conclude that the suggested framework is useful in constructing an effective diagnosis procedure.     

An inverse geometry problem for the localisation of skin tumours by thermal analysis

In this paper, the dual reciprocity method (DRM) is coupled to a genetic algorithm (GA) in an inverse procedure through which the size and location of a skin tumour may be obtained from temperature measurements at the skin surface. The GA is an evolutionary process which does not require the calculation of sensitivities, search directions or the definition of initial guesses. The DRM in this case requires no internal nodes. It is also shown that the DRM approximation function used is not an important factor for the problem considered here. Results are presented for tumours of different sizes and positions in relation to the skin surface.     

Symmetric Level Index Arithmetic in Simulation and Modeling

This paper begins with a general introduction to the symmetric level-index, SLI, system of number representation and arithmetic. This system provides a robust framework in which experimental computation can be performed without the risk of failure due to overflow/underflow or to poor scaling of the original problem. There follows a brief summary of some existing computational experience with this system to illustrate its strengths in numerical, graphical and parallel computational settings. An example of the use of SLI arithmetic to overcome graphics failure in the modeling of a turbulent combustion problem is presented. The main thrust of this paper is to introduce the idea of SLI-linear least squares data fitting. The use of generalized logarithm and exponential functions is seen to offer significant improvement over the more conventional linear regression tools for fitting data from a compound exponential decay such as the decay of radioactive materials.     

Experimental Observations and Modelling of Compaction Bands in Oedometric Tests on High Porosity Rocks

Abstract:  Experimental results obtained in a series of displacement controlled oedometric tests on soft rocks are presented. Four different materials characterised by a high void ratio have been examined; three natural soft rocks and an artificial one. The materials under investigation were conchyliates stone, calcarenite, pumice stone and Gasbeton. In order to monitor the stress path as well, a soft oedometer ring was designed and constructed for the measurement of the radial stresses. The observed behaviour can be divided in three phases. After an initial phase in which the mechanical response is essentially elastic, a second phase starts, in which bonds are progressively broken, so that in the axial stress–strain curve a stress decrease is recorded and in some cases, a sort of 'curl' appears in the stress path. This is associated to the occurrence of strain non-homogeneities in the form of compaction bands. In the final part of the experiment the axial stress increases exponentially and the stress path returns to be linear, as the one expected for a cohesionless material. The experimental behaviour is reproduced by means of an elastoplastic strain-hardening/softening constitutive model and the occurrence of compaction bands is theoretically predicted.     

Mechanical behaviour of non-structural concrete made with recycled ceramic aggregates

In order to reduce the volume of ceramic waste from the construction industry, it is possible, among other applications, to use it as aggregates in the production of non-structural concrete artefacts. The main characteristics of such aggregates as well as those of the fresh and hardened concrete made with them (after a standardized pre-saturation procedure) are presented here and compared with those of conventional materials (primary stone aggregates and the concretes made exclusively with them), within a larger experimental investigation to maximize the reuse and reutilization of construction and demolition waste. The results show that there is a potential for the use of these ceramic aggregates in elements in which the primary requirement is not compressive strength but tensile strength and abrasion resistance, such as for concrete pavement slabs.     

Measurement of the Intrinsic Thermal Conductivity of a Multiwalled Carbon Nanotube and Its Contact Thermal Resistance with the Substrate

The intrinsic thermal conductivity of an individual carbon nanotube and its contact thermal resistance with the heat source/sink can be extracted simultaneously through multiple measurements with different lengths of the tube between the heat source and the heat sink. Experimental results on a 66‐nm‐diameter multiwalled carbon nanotube show that above 100 K, contact thermal resistance can contribute up to 50% of the total measured thermal resistance; therefore, the intrinsic thermal conductivity of the nanotube can be significantly higher than the effective thermal conductivity derived from a single measurement without eliminating the contact thermal resistance. At 300 K, the contact thermal resistance between the tube and the substrate for a unit area is 2.2 × 10^?8 m² K W^?1, which is on the lower end among several published data. Results also indicate that for nanotubes of relatively high thermal conductance, electron‐beam‐induced gold deposition at the tube–substrate contacts may not reduce the contact thermal resistance to a negligible level. These results provide insights into the long‐lasting issue of the contact thermal resistance in nanotube/nanowire thermal conductity measurements and have important implications for further understanding thermal transport through carbon nanotubes and using carbon nanotube arrays as thermal interface materials.     

Piezoelectric Vibration-Type Tactile Sensor Using Elasticity and Viscosity Change of Structure

We propose a new tactile sensor utilizing piezoelectric vibration. This tactile sensor has a high sensitivity, wide measurement range, pressure resistance, flexibility, and self-sensing function. This tactile sensor comprises two piezoelectric materials. One is used for the vibration of the sensor element and the other is used for the measurement of the change in mechanical impedance induced by an external force. We achieved the wide measurement range by implementing two ideas. One was to apply the external force to the sensor element through an elastic body and the other was to use two or more modes of vibration. Moreover, for the elastic body, it is preferable to use a material whose elasticity and viscosity are easily changed by an external force, such as a gel. In this study, first, this tactile sensor was analyzed, and then its characteristics were derived. The analytical results qualitatively corresponded to the experimental results. Next, a prototype tactile sensor was fabricated and evaluated. The evaluation results showed that this tactile sensor can measure a pressure of 2.5 Pa or less and a pressure of 10 kPa or more and its pressure resistance is 1 MPa or more.     

井斜实时测量方法研究

介绍了用重力加速度传感器进行井斜实时测量的方法，阐述了重力加速度传感器的工作原理及其测量井斜的算法，从理论角度分析了实钻中严重干扰井斜信号的因素——噪声、钻具的振动和随机转动，其中噪声和振动信号可采用低通滤波器滤除，而转动使加速度计因离心力产生的测量信号失真，则可通过诸如转速补偿之类的修正去除。经专门的实验装置验证此井斜测量方法和信号处理方法可进行较高精度的井斜实时测量，为高精度的井斜控制奠定了基础。     

GZ-10型高精度数字式表面电阻测试仪的研制

静电火花是煤矿、加气站等有危险气体场所发生爆炸的主要点火源之一。为防止静电火花产生,关键是设备和材料必须具有抗静电性能,而评价聚合物制品抗静电性能的主要方法是用表面电阻测试仪测量其表面电阻。本文介绍了研制的新型GZ-10型高精度数字式表面电阻测试仪的系统组成及硬件设计。该表面电阻测试仪采用低阻档和高阻档两组测试电路,高阻档测试电路测量双取样电阻的电压,低阻档电路采用比例法,克服了普通表面电阻测试仪因被测电压或电流的变化而变化的缺点,保证了测量的准确性。     

Consolidation effectiveness of modified Si-based nanocomposites applied to limestones

One of the main issues in the field of Monument Protection is the degradation of limestones as a result of the action of various weathering mechanisms. The modification of widely used silicon-based materials for stone consolidation is intended to overcome the well-known drawbacks of these materials, such as shrinkage and cracking tendency during drying. The addition of nano-dispersions into a silica matrix aims to enhance their effectiveness in several ways, by improving their properties and their viscoelastic behavior. The objective of the current research was the application and evaluation of Si-based modified nanocomposites of optimized composition. The materials were applied to two types of porous stone and the assessment of their compatibility and performance was carried out by using both laboratory techniques and methods (SEM, MIP, TMA, Water Absorption by Capillarity, determination of Water Vapor Permeability) and non-destructive techniques (Ultrasound Velocity determination, Colorimetry). To study the resistance of the treated samples to soluble salt crystallization, accelerated aging tests were performed in sodium sulfate cycles. The modified consolidants consist of an ethyl silicate matrix reinforced with colloidal silica (SiO₂) nano-particles and titania (TiO₂) particles. Based on the results, the consolidating material does not significantly alter the characteristics of the microstructure and the appearance of stones, allowing the passage of water vapor, while increasing their mechanical properties. Furthermore, the accelerated ageing tests revealed that the treated samples have a higher resistance to the action and crystallization of soluble salts in comparison to untreated.     

A procedure to study thermo- and electrophysical properties of materials

We describe a measurement procedure and the construction of an automatic measuring complex to study thermal conductivity by an absolute stationary method and also electrical conductivity and thermal EMF of materials in a temperature range from −60 to +4400 ° C. The use of a specialized microprocessor system to perform stationary measurements and to control parameter measurement processes in combination with highgrade measuring devices and equipment developed for this procedure enables high accuracy of measurements. Test studies performed on reference samples show that the thermal conductivity measurement error does not exceed 4 and 3% for electrical conductivity and thermal EMF, respectively. In the development of devices and equipment for this measuring complex, unconventional engineering, schematic, and programming solutions are implemented. The application of a microprocessor control system together with the software developed allows the measurements to be performed automatically.     

Zyklisches Werkstoffverhalten sprühkompaktierter Aluminiumwerkstoffe. Kennwerte für die Bauteilbemessung: Von der Probe zum Bauteil

The fatigue behaviour of spray compacted aluminium materials. Material properties for component design data: From specimen to component. Spray compacted, high performance aluminium alloys (DISPAL = DISpersion hardened Aluminium) are characterised by their high strength, high Young’s modulus, good wear resistance and low coefficient of thermal expansion. These properties vindicate both the application of these materials and the increasing interest of the automobile manufacturers. Within the framework of a bilateral project, tests were carried out by varying different parameters under both strain‐ and load‐controlled conditions in order to describe the fatigue behaviour of these materials.