光源相关色温与分布温度的实验分析

在国家色温基准改造课题中,通过光谱辐射测量法得到色温副基准灯的相对光谱功率分布,分别采用四种不同的算法计算出光源的相关色温以及分布温度。为了比较这些计算方法的差别,由相关色温和分布温度反算出相应的光谱功率分布,分析了与光源原始分布的偏差。对采用不同算法得到的色坐标进行了对比,进一步阐明了光源的分布温度与相关色温之间的区别和联系。     

温度对高温超导材料(HTS)性能的影响

超导电力技术将为电力工业带来重大的技术突破,其在电力系统中的应用具有重大意义,而失超保护则是对超导电力系统安全运行的保障。在失超保护设计中正确把握温升对超导材料性能的影响非常重要。该文以高温超导带材为样品,通过实验实际测得加热到不同温度时样品恢复后的临界电流,研究了超导材料经历不同温升后临界电流的变化情况。结果显示:对于同一样品,超过一定温度以后,材料将发生不可恢复的变化,超导材料经历一定温升后,其临界电流会下降,温度越高,下降幅值越大,高温的经历对材料的损伤是不可恢复的。     

Characteristics of the spatiotemporal distribution of daily extreme temperature events in China: Minimum temperature records in different climate states against the background of the most probable temperature

Based on the skewed function,the most probable temperature is defined and the spatiotemporal distributions of the frequencies and strengths of extreme temperature events in different climate states over China are investigated,where the climate states are referred to as State I,State II and State III,i.e.,the daily minimum temperature records of 1961-1990,1971-2000,and 1981-2009.The results show that in space the frequency of high temperature events in summer decreases clearly in the lower and middle reaches of the Yellow River in State I and that low temperature events decrease in northern China in State II.In the present state,the frequency of high temperature events increases significantly in most areas over China except the north east,while the frequency of low temperature events decreases mainly in north China and the regions between the Yangtze River and the Yellow River.The distributions of frequencies and strengths of extreme temperature events are consistent in space.The analysis of time evolution of extreme events shows that the occurrence of high temperature events become higher with the change in state,while that of low temperature events decreases.High temperature events are becoming stronger as well and deserve to be paid special attention.     

Connection between the low temperature anomaly in glasses and the glass transition temperature

The low temperature specific heat anomaly in water-doped K-Ca nitrate glass has been found to scale with the reciprocal glass transition temperature. Similarly, the anomaly in Na₂O-containing and in neutron-irradiated silica scales with the reciprocal fictive temperature. These observations lead to the suggestion that the frozen-in disorder is connected with the low temperature anomaly characteristic of the glassy state.     

瞬态大电流测量结温中校温曲线弯曲现象的研究

利用脉宽250 μs、占空比5%的0–1.5 A脉冲电流, 分别在50, 70, 90, 110, 130 ℃条件下, 对TO-247-2L封装型PIN快恢复二极管大电流下的校温曲线进行了测量分析. 研究发现, 恒定大电流条件下, 二极管的校温曲线随温度变化发生弯曲. 分析表明, 弯曲现象主要是由于串联电阻受迁移率的影响随温度发生变化而引起的. 通过实验测量及理论计算, 得到了准确的非线性校温曲线, 从而减小了瞬态大电流测量结温中的误差.     

钻井液径向温度梯度与轴向导热对井筒温度分布影响

本文基于井筒与地层间能量平衡原理, 将井筒钻井液划分成不同径向单元网格, 建立了考虑径向温度梯度条件下钻井液层间温度模型; 同时引入钻井液轴向导热项, 建立了钻井液轴向导热温度模型, 将数学模型应用隐式有限差分法离散与求解. 计算结果表明: 钻井液径向温度梯度对井筒径向与轴向温度产生的误差分别为0.15 ℃和0.2 ℃左右; 而钻井液轴向导热对井筒温度分布几乎不产生影响. 因此, 通过建立的数学模型进行系统分析表明, 在建立井筒-地层耦合瞬态传热模型时可忽略两者对井筒温度分布的影响. 基于数学建模方法验证了以前学者模型假设条件的正确性, 为油气井与地热井井下温度分布规律深入研究奠定了可靠的理论基础. 关键词： 径向温度梯度 轴向导热 井筒温度 瞬态传热模型     

带温度补偿的分布式光纤温度传感系统设计

针对分布式光纤温度传感系统(Distributed Optical Fiber Temperature Sensing System,DTS)在线测温精度不高的问题,提出了使用光纤布拉格光栅(Fiber Bragg Grating,FBG)解调仪对DTS进行温度补偿。对不带温度补偿的DTS进行了温度测量和数据分析,证明了进行温度补偿的必要性。设计了带温度补偿的DTS并进行了温度测试。实验结果表明,在使用FBG解调仪对DTS进行温度补偿后,DTS的温度精确度可以达到0.3℃。     

由电感测量铁氧体材料的居里温度

为测量铁氧体磁芯材料的居里温度，将含有铁氧体磁芯的螺绕环置于自制的可变温度的样品室中，用电感测量仪测量螺绕环在不同温度下电感量．得到电感随温度的变化曲线，从而确定磁芯的居里温度．     

等离子体针放电的振动温度和气体温度研究

大气压等离子体针空气放电产生的低温等离子体由于脱离了真空装置,在工业上具有广泛的应用前景。本文采用等离子体针装置在空气中产生了稳定的大气压等离子体羽,并利用光谱法对等离子体羽的振动温度和气体温度进行了研究。结果发现大气压空气等离子体羽的放电区域分为强光区和弱光区。放电发光信号是宽度为几个微秒的脉冲。研究结果表明等离子体振动温度随空间位置不同在2 500～3 000K范围变化。振动温度在强光区随着远离针尖距离的增大振动温度呈上升趋势,在5mm左右存在极大值,在弱光区随着远离针尖距离的增大振动温度呈下降趋势。与其相似,弱光区放电的气体温度随着远离针尖距离增大,从640K降低到540K。这些结果对大气压空气放电的工业应用具有重要意义。     

Effects of temperature on the structure of neutron stars at high temperature

In Newtonian physics, higher temperature leads to higher thermal pressure, which provides stronger support against the gravitational contraction of stars. However, in the temperature range of tens of MeV involved in the evolution of a proto-neutron star or a higher massive neutron star, the effects of temperature are richer. We showed that, for a high temperature neutron star (HTNS) constructed with a realistic equation of state (EOS), the HTNS may expand or contract during cooling, the central density may increase or decrease, the quasi-normal mode oscillation frequencies may increase or decrease, and in particular, (i) independent of the EOS, for a HTNS of a given mass, there exists a maximum temperature \(T_{max}\) that it could ever attend at birth (with the value of \(T_{max}\) different for different EOS), and (ii) for the Hempel EOS and the Shen EOS, there is a range of mass that the HTNS may gravitationally collapse after a period of radiative cooling; however, for the Lattimer–Swesty EOS and Banik EOS, no delayed collapse is possible. Our study, which describes the cooling of HTNSs with simple quasi-stationary TOV sequences, provides an understanding of the effects of the thermal energy/pressure at high temperature, and a demonstration that different EOSs can lead to qualitatively different evolution paths.     

Existence of temperature on the nanoscale

We consider a regular chain of quantum particles with nearest neighbor interactions in a canonical state with temperature T. We analyze the conditions under which the state factors into a product of canonical density matrices with respect to groups of n particles each and under which these groups have the same temperature T. In quantum mechanics the minimum group size n(min) depends on the temperature T, contrary to the classical case. We apply our analysis to a harmonic chain and find that n(min)=const for temperatures above the Debye temperature and n(min) proportional to T(-3) below.     

低温真空冷冻干燥室内温度特性的研究

真空冷冻干燥设备广泛应用于药品、食品等的干燥领域,该干燥方式能避免药品、微生物等产生变性或失去生物活力,但是能耗较大,且干燥室内的温度在真空条件下,比较难于控制。文中从三个方面对其温度特性进行了实验研究:真空度对温度特性的影响;板面温度对于冻干瓶内温度控制的影响;保护气对于冻干瓶内温度控制的影响。     

Surface magnetization near the critical temperature and the temperature dependence of magnetic-electron scattering from NiO

The temperature dependence of low energy electrons scattered by the exchange interaction in antiferromagnetic NiO is obtained over the temperature range T_N?T?295 K. By doping the N₁O crystal with (less than 0.1 %) Li, the conductivity was increased sufficiently to obtain data at lower temperatures than previously reported.     

Influence of the temperature on the heat of formation of nickel monoxide at high temperature

In order to see whether the heat of formation ΔH⁰ of the insulating transition metal monoxides shows any change at high temperatures, this property has been accurately measured for NiO by the electrochemical method in the temperature range 743–1323 K. The results show that ΔH⁰ changes from ? 56.10 kcal mol^?1 to ? 55.66 ± 0.08 kcal mol^?1 as the temperature is increased through 913 K. The significance of the heat of formation is discussed from the viewpoint of electronic structure of this compound.     

Low temperature properties of the Kondo insulator FeSi

In this paper we study the low temperature (T) properties of the Kondo insulator FeSi within the X-boson approach. We show that the ground state of the FeSi is metallic and highly correlated with a large effective mass; the low temperature contributions to the specific heat and the resistivity are of the Fermi-liquid type. The low temperature properties are governed by a reentrant transition into a metallic state, that occurs when the chemical potential crosses the gap and enters the conduction band, generating a metallic ground state. The movement of the chemical potential is due to the strong correlations present in the system. We consider the low temperature regime of the Kondo insulator FeSi, where the hybridization gap is completely open. In this situation we identify the two characteristic temperatures: the coherence temperature T₀ and the Kondo temperature T_KL. In the range T < T₀, we identify a regime characterized by the formation of coherent states and Fermi-liquid behavior of the low temperature properties; in the range T_KL > T > T₀, we identify a regime characterized by an activation energy. Within the X-boson approach we study those low temperature regimes although we do not try to adjust parameters to recover the experimental energy scales.     

Laying the ghost of the relativistic temperature transformation

Using the Unruh-DeWitt detector, it is shown that a universal and continuous Lorentz transformation of temperature cannot exist for black-body radiation. Since any valid Lorentz transformation of temperature must be able to deal with black-body radiation, it is concluded that a universal and continuous temperature transformation does not exist.     

Conformational temperature characterizing the folding of a protein

The time sequences of the molecular dynamics simulation for the folding process of a protein is analyzed with the inherent structure landscape which focuses on the configurational dynamics of the system. Time-dependent energy and entropy for inherent structures are introduced, and from these quantities a conformational temperature is defined. The conformational temperature follows the time evolution of a slow relaxation process and reaches the bath temperature when the system is equilibrated. We show that the nonequilibrium system is described by two temperatures, one for fast vibration and the other for slow configurational relaxation, while the equilibrium system is described by one temperature. The proposed formalism is applicable widely for systems with many metastable states.     

The determination of the temperature factor

The paper deals with a method for finding the temperature factor when determining crystal structures.     

波长检测技术在温度测量中的应用

提出一种波长检测技术实现温度测量的方法,利用FBG传感器对温度等物理量实施监测,具有测试精度高,应用场合不受限制等特点,当环境参数发生变化时,光纤光栅的有效折射率和光栅周期会受到影响,将引起光纤光栅峰值波长的偏移,依据反射光谱结构的变化,可知道其温度的变化趋势。实验测试结果表明,在温度变化0.1°,波长变化1pm,温度和波长具有良好的线性关系。     

Linear temperature dependence of low temperature pyroelectric coefficient

Due to the deformation of electronic charge clouds, the Dick-Overhauser exchange charge in ionic materials is shown to have quadratic temperature dependence as T tends to zero in non-centrosymmetric crystals. It follows that the pyroelectric coefficient π has a linear temperature dependence in the same low temperature limit. The order of magnitude of π obtained theoretically by a simple model at T = 5 K is 2 × 10^?7 μC cm^?2 K^?1, which is in fairly good agreement with that obtained experimentally on LiTaO₃ by Lines.