Design,fabrication, and testing of fiber Bragg grating sensors for cryogenic long-range displacement measurement

It is essential to measure the shrinkage/expansion and positioning/aligning of magnets and to control valve displacement which plays a vital role in experiments like the Karlsruhe tritium neutrino experiment beam tube and Cryo pumps. Hence, a displacement sensor which, over a long working range, can be operated under extreme environmental conditions needs to be developed. Fiber Bragg gratings (FBG) have been considered to be excellent sensor elements useful for a variety of applications. This paper will discuss a long range displacement sensors based on fiber Bragg gratings for cryogenic temperature applications. The cryo pump inlet valve control requirements have been taken as example specifications for sensor design. To achieve the development goal, a proper signal transducer and sensor package were designed. A study of the strain transmission of surface-bonded FBG was conducted. The influence of bonding thickness and bonding length was reported. The design, fabrication, and performance were tested at low temperature of around 77 K. The sensor performance was found to be satisfactory at both room temperature and 77 K and linearly for long-range displacement of 550 mm with 14 pm/mm sensitivity and 0.142 mm accuracy.     

Investigation of cryogenic cooling effect in reaming Ti-6AL-4V alloy

This research article is based mainly on the investigation of the effect of cryogenic machining, while reaming Titanium grade 5 alloy (Ti-6Al-4V) material. Cutting speed (V_c) and feed rate (f) are two input parameters at three different levels for a constant depth of the hole. The output parameters considered by using a cryogenic LN₂ cooling compared to a conventional flood cooling are torque (M_t), thrust force (F_t), cutting temperature (T), quality of the hole (circularity and cylindricity), surface roughness (R_a) and chip morphology. The results show cryogenic liquid nitrogen (LN₂) cooling resulting in 15–31% reduction in the cutting temperature, 23–57% reduction in the thrust force and 14–65% reduction in torque. Higher surface roughness, circularity (Cir) and cylindricity (Cyl) were observed in the cryogenic LN₂ cooling condition. Furthermore, better chip breakability was observed in the cryogenic LN₂ cooling condition. No drastic change in the microstructure was observed in both flood and cryogenic LN₂ cooling. Increase in microhardness by 10–16% and 8–19% in cryogenic LN₂ cooling over flood cooling was observed.     

Empirical correlations for the solubility of pressurant gases in cryogenic propellants

We have analyzed data published by others reporting the solubility of helium in liquid hydrogen, oxygen, and methane, and of nitrogen in liquid oxygen, to develop empirical correlations for the mole fraction of these pressurant gases in the liquid phase as a function of temperature and pressure. The data, compiled and provided by NIST, are from a variety of sources and covers a large range of liquid temperatures and pressures. The correlations were developed to yield accurate estimates of the mole fraction of the pressurant gas in the cryogenic liquid at temperature and pressures of interest to the propulsion community, yet the correlations developed are applicable over a much wider range. The mole fraction solubility of helium in all these liquids is less than 0.3% at the temperatures and pressures used in propulsion systems. When nitrogen is used as a pressurant for liquid oxygen, substantial contamination can result, though the diffusion into the liquid is slow.     

低温贮运设备选型中有关问题的探讨

以一台 15m3 、设计压力为 1 0MPa、粉末真空绝热低温液体贮罐为例 ,分析了用户选型时进行经济性分析的重要性及设计人员对日蒸发率的误解 ;推荐了计算贮运设备单位漏热量的一种反算方法。     

内压球壳大开孔接管区电阻应变测量中不确定度的评定

本文对内压球壳大开孔接管区电阻应变测量进行了测量不确定度的B类评定 ,发现其外壁应力测量相对标准不确定度一般不超过 2 % ,可满足实验应力分析要求     

Testing of strain-gauge pressure transducers up to 3.5 MPa at cryogenic temperatures and in magnetic fields up to 6 T

The characteristics of four commercial strain-gauge pressure transducers suitable for measurements in a temperature range from 4.2 to 293 K were determined in the presence of magnetic fields up to 6 T. The highest pressure measured was 3.5 MPa. Tests showed that if the transducers are used in these conditions and no corrections are made, uncertainties up to 19% of the transducer full scale may be inherent in measurements. When such high error levels are unacceptable, the transducers must be individually calibrated under the working conditions: in this way the uncertainties in pressure measurements can usually be kept below 1 % of the transducer full scale.     

低温用膨胀珍珠岩绝热性能的实验研究

本文以常用低温保温材料膨胀珍珠岩 (珠光砂 )为研究对象 ,实验测量了在稳态和非稳态传热条件下的导热性能、热扩散性能及其随温度的变化规律 ,并对两种传热条件下的绝热特性进行了分析和研究 ,为工程应用提供可靠的理论依据 ,也为低温绝热方案的选择及优化提供参考资料     

两类声速测温方法的研究与比较

声学测温是一种先进的温度测量方法，与传统方法相比，具有很多优势。而在声学测温的各种方法中，基于声波传播时间的声速测温方法又是一种比较好的、应用更广泛的方法。本文着重对气体介质中声速测温的两类测量方法进行了研究和比较，分析了其各自的优势与不足。结果表明，直接传播测量方法是一种更有潜力、应用更广泛的测温方法。     

Main problems of the unification and standardization in developing special purpose displacement transducers

The main problems of unification that arise in the development of special purpose displacement transducers are formulated. Ways are considered for resolving these problems, and the main concepts and definitions used in unification and standardization of transducer equipment are provided. Translated from Izmeritel’naya Tekhnika, No. 12, pp. 56–58, December, 2008.     

Investigation of failure behavior of two different types of Zircaloy clad tubes used as nuclear reactor fuel pins

Nuclear reactor fuel pins act as barriers to the release of radioactive fission products to the coolant flowing around these thin-walled tubes and hence they prevent the leakage of radioactivity to the surroundings of reactor core. These tubes are of small thickness in order to have less resistance in the path of heat flow from the fuel to the coolant. Investigation of failure behavior of these fuel clad tubes is of utmost importance to the designers and plant operators in order to ensure the maximum residence time of the fuel bundles inside the reactor core as well as to ensure minimal activity during operation and refueling activities. Various types of zirconium based alloys are used to manufacture these pins. The focus is to obtain better strength, ductility, corrosion resistance, oxidation resistance, and minimal creep including those due to irradiation-assisted damage and deformation processes. Two number of such types of alloys, namely, re-crystallization annealed Zircaloy-2 and stress-relief annealed Zircaloy-4, have been investigated in this work for their fracture behavior. As standard fracture mechanics specimens cannot be machined from these thin-walled tubes, non-standard specimens with axial cracks have been used in this work. Load normalization technique has been used to evaluate crack growth during loading of these specimens. It was observed that the re-crystallization annealed Zircaloy-2 specimens have higher initiation fracture toughness as well as higher resistance to crack growth compared to the other type of specimens. In order to understand the micro-structural aspects of the fracture resistance behavior of these materials, further investigation incorporating optical and transmission electron microscopy have also been carried out. It was concluded that the higher fracture resistance behavior of the re-crystallization annealed Zircaloy-2 specimens can be attributed to the presence of finer grain and sub-grain micro-structure, very low dislocation density and other defects in the material.     

大型低温液体贮存站贮罐设计选型论证

分析论证了容积大于 12 5m3 的LNG卫星站贮罐设计选型技术方案 ,评价了A (子母罐 )、B (球罐 )、C (圆筒罐 )、D (常压罐 +输液泵 )、E (集群罐 )方案各自的特点及其适用范围 ,提出了建造大型真空粉末绝热压力罐的模式及用户建站贮罐设计选型时的参考原则     

两种不同形式蒸发冷却房间空调器的性能测试

分别选择直接式和间接式蒸发冷却房间空调器进行性能测试，并进行比较，指出直接式和间接式各自特点。在此基础上提出并论证将直接式和间接式结合起来的二级蒸发冷却用于房间空调器的可行性和优越性。     

Incorporating Artificial Neural Networks in the dynamic thermal–hydraulic model of a controlled cryogenic circuit

A model based on Artificial Neural Networks (ANNs) is developed for the heated line portion of a cryogenic circuit, where supercritical helium (SHe) flows and that also includes a cold circulator, valves, pipes/cryolines and heat exchangers between the main loop and a saturated liquid helium (LHe) bath. The heated line mimics the heat load coming from the superconducting magnets to their cryogenic cooling circuits during the operation of a tokamak fusion reactor. An ANN is trained, using the output from simulations of the circuit performed with the 4C thermal–hydraulic (TH) code, to reproduce the dynamic behavior of the heated line, including for the first time also scenarios where different types of controls act on the circuit. The ANN is then implemented in the 4C circuit model as a new component, which substitutes the original 4C heated line model. For different operational scenarios and control strategies, a good agreement is shown between the simplified ANN model results and the original 4C results, as well as with experimental data from the HELIOS facility confirming the suitability of this new approach which, extended to an entire magnet systems, can lead to real-time control of the cooling loops and fast assessment of control strategies for heat load smoothing to the cryoplant.     

Pd77.5Cu6Si16.5剪切模量的光纤位移检测

提出用反射型光纤位移法对非晶体Ｐｄ７７．５Ｃｕ６Ｓｉ１６．５的剪切变模量的测试方法。讨论了测试原理,得到了测量非晶态微应变的一种新途径,分析了误差来源,对光纤测距条件进行了修正,提出了约束条件。     

The relationship between the sweep efficiency and displacement efficiency of function polymer in heterogeneous reservoir after polymer flood

A function polymer is considered to be a kind of potential Enhanced Oil Recovery (EOR) agent that can further enhance oil recovery after polymer flooding. Based on the typical geologic features and development history of the Daqing Oilfield, a function polymer displacement experiment was conducted using a 3D laboratory physical model with a high-permeability channel between the injection end and the production end to study the EOR mechanism of the function polymer solution. In this article, the displacement feature and oil/water distribution of function polymer flooding is presented, as well as the swept effect in pores of different sizes. The experimental results show that the function polymer flooding after regular polymer flooding further enhances oil recovery by 10.29%. Moreover, the increment of sweep efficiency and displacement efficiency reaches 3.02% and 11.78%, respectively, which clearly demonstrates that the function polymer system improves the displacement efficiency by the emulsification effect and increases the displacement efficiency by the plugging effect. Combined with nuclear magnetic resonance imaging, the swept effect in pores of medium size tends to occupy the dominate role in the performance of function polymer flooding, rather than that in pores of smaller or larger size. By analyzing the EOR mechanism of the function polymer system, this work offers a novel theoretical reference for future decision-making in tertiary recovery.     

Investigation of turbo-molecular pumps in strong magnetic fields

In modern particle and accelerator physics as well as in nuclear fusion experiments turbo-molecular pumps (TMP) are used in close proximity to super-conducting magnets. This can cause considerable heating of the fast moving rotor by eddy currents, which can ultimately lead to the destruction of the pump. Motivated by the KATRIN neutrino experiment, where TMPs are operated close to super-conducting magnets, a measurement programme has been elaborated to investigate the effect of magnetic fields on TMPs. An infra-red pyrometer has been used to measure the temperature of the revolving rotor. In addition the effect of different gas loads on the temperature was investigated. With these data a simplified model has been developed to predict the evolution of the rotor temperature over time, using easy to measure parameters. Here we introduce the new model and present first measurements and their application in predicting the rotor temperature in the pulsed field of a nuclear fusion experiment.     

基于超导磁场环境真空测量电离规磁屏蔽结构仿真研究

聚变装置超导磁场环境下真空测量电离规因灯丝变形、带电粒子轨迹变化等物理机制导致真空测量精度不高,不能满足工程精确测量的需求。基于磁屏蔽的理论,构建了半封闭式和开放式的两种多层磁屏蔽结构模型,利用Maxwell有限元软件,仿真研究了结构材料层不同厚度和不同磁场方向等条件下磁屏蔽效能的变化规律。结果表明,屏蔽效能随铁层材料径向厚度的增加而增大,铁层材料端部厚度对其影响较小;超导材料层厚度对屏蔽效能影响较小;磁场方向角在0°~90°范围内,屏蔽效能先减后增,并在90°(屏蔽结构轴向与磁场方向平行)时达到最大值。为电离规在复杂磁场应用条件下的屏蔽结构工程设计提供了依据。     

Investigation of different types of nano drug delivery systems of atorvastatin for the treatment of hyperlipidemia

Abstract

Different nanoparticles, namely solid lipid nanoparticles, nanocrystals and nanosponges loaded with atorvastatin were successfully fabricated with desirable technological properties which reckoned promising methods of their preparation. Further, suitable characterization and evaluation parameters for in-vitro and in-vivo studies were conducted which led to increase in drug’s bioavailability, provided better in-vivo efficacy and reduced toxicity in treating hyperlipidemia systemically. Particle sizes were found to be less than 300?nm with minimal polydispersity indices and maximized entrapment efficiency which are pre-requisites for their absorption in intestines. Drug release studies showed sustained release for a prolonged period, which was justified by release kinetics. Augmented bioavailability and reduced lipoprotein levels were key observations. In addition, reduced hepatotoxicty, decreased myotoxicity and diminished drug distribution were also the important highlights of these developed nanosystems as compared with the pure drug and marketed formulation. Histopathology of liver confirmed reduced hepatotoxicity. An elaborate comparison of these nanoparticles along with pure drug and marketed formulation concluded that nanosponges are potentially one of the best nanosystems for treating hyperlipidemia by systemic delivery.     

Prioritising the types of manufacturing flexibility in an uncertain environment

Researchers have stressed that manufacturing system flexibility research requires a quantitative model allowing a manufacturing system to prioritize its flexibility dimension and promote the performance of the manufacturing system. A quantification model presented in the present research is demonstrated to assess the degree of environmental uncertainty and illustrates a method for delivering the requirement of flexibility improvement for the manufacturing system so that the company is able to prioritize the types of manufacturing flexibility which a manufacturing system requires in an uncertain environment. Quantitative approaches including quality function deployment (QFD), analytical hierarchy process (AHP), and grey relational analysis (GRA) have been employed to find a means for improving the flexibility of a manufacturing system to cope with environmental uncertainty. QFD is the focal approach for the deployment of the integrated structure of the research. AHP is applied to explore the relative weighted importance of environmental uncertainty factors, while GRA is used to find out the relationships between manufacturing flexibility and environmental uncertainty. A combination of these approaches reveals a useful tool for managers to prioritize the types of flexibility which a manufacturing system requires for coping with an uncertain environment. In particular, the present research studied the manufacturing flexibility requirements of a food company in Taiwan.