基于铂电阻传感器的动态特性试验研究

由于热电阻测温法的测温精度高、稳定性好、测温范围广,被广泛应用于油田勘探开发中,但该测温方法常因传感器自身材料属性的原因对测温的实时性造成影响。该文以油田井温测井中常用的铂热电阻为研究对象,根据热力学定律,利用测井软件warrior及多路温度测试仪(安柏AT4204),完成了对铂热电阻动态响应过程的记录,实现了实验数据的自动采集;再利用MATLAB软件将实验数据进行处理,得出铂热电阻在不同温度、不同直径及不同长度下的感温时间常数的数学模型。在保证测量精度的情况下,为以后在测井过程中优化测速提供必要的数据支持和理论指导。

电子压力计的温度性能

目前的电子压力计都具备温度测试功能,耐温有的达到125℃,而某些高精度耐温可以高达150℃。建议根据压力计使用的具体情况,定期做温度周期检定。各型号压力计在空气浴给出的标准温度内示值情况比较准确,误差均在±2℃以内。各型号压力计到达80℃的感温时间基本都在130 s之内。温度传感器外置的电子压力计感温时间很短,可以在10 s左右达到水浴温度,感温性能明显好于温度传感器内置压力计。

桑蚕“两广二号”蚕种冷藏试验

本文对“两广二号”蚕种用三种冷藏方法进行了比较试验，结果表明：复式冷藏法有效期限前后两期冷藏２００～２２０天以内，单式冷藏法冷藏１２０～２００天，滞育卵冷藏浸酸法冷藏１００～１８０天，可得到有实用性价值的蚕种，复式冷藏法对延长滞育蚕种的冷藏有显著效果，如果适当推迟中间感温时间还可延长蚕种有效冷藏期。

Time-temperature-property curves for quench sensitivity of 6063 aluminum alloy

The quench sensitivity of 6063 alloy was investigated via constructing time-temperature-property（TTP） curves by interrupted quenching technique and transmission electron microscopy（TEM） analysis.The results show that the quench sensitivity of 6063 alloy is lower than that of 6061 or 6082 alloy,and the critical temperature ranges from 300 to 410℃ with the nose temperature of about 360℃.From TEM analysis,heterogeneous precipitate β-Mg2Si is prior to nucleate on the（AlxFeySiz） dispersoids in the critical temperature range,and grows up most rapidly at the nose temperature of 360℃.The heterogeneous precipitation leads to a low concentration of solute,which consequently reduces the amount of the strengthening phase β＇＇ after aging.In the large-scale industrial production of 6063 alloy,the cooling rate during quenching should be enhanced as high as possible in the quenching sensitive temperature range（410-300℃） to suppress the heterogeneous precipitation to get optimal mechanical properties,and it should be slowed down properly from the solution temperature to 410℃ and below 300℃ to reduce the residual stress.

Quenching sensitivity and heterogeneous precipitation behavior of AA7136 alloy

The quenching sensitivity of AA7136 alloy was investigated by time−temperature−property(TTP)diagrams,and the heterogeneous precipitation behavior during isothermal holding was investigated using scanning electron microscopy,scanning transmission electron microscopy and high resolution transmission electron microscopy.Based on 99.5%TTP diagram,the nose temperature is determined to be about 346℃ with the transformation time of about 0.245 s.The precipitation ofη(MgZn_(2)),T(Al_(2)Zn_(3)Mg_(3)),S(Al_(2)CuMg)or Cu−Zn-rich Y phases can be found depending on isothermal holding temperature and time,and it is described in a time−temperature−precipitation diagram.The size and area fraction of isothermal holding induced phase particles increase,which results in the decrease of hardness of samples after aging.The quantitative contribution to loss of hardness by grain boundaries/subgrain boundaries and dispersoids in the matrix is discussed based on the amount of heterogeneous precipitation related to them.

Impact of cold indoor thermal environmental conditions on human thermal response

To explore the thermal responses under the non-thermal equilibrium cold environmental conditions,a laboratory study was conducted in climate chamber.The local skin temperatures and thermal sensation of 20 subjects were recorded at 10 min intervals for 90 min under air temperatures of 7.4,9.1,11 and 15 °C.The results show that both local skin temperatures and mean skin temperature decrease not only with the drop of ambient air temperature but also with the exposure time.Local thermal sensation and overall the thermal sensation have the similar temperature-varying and time-varying characteristics.Predicted mean vote(PMV) model cannot correctly predict the thermal sensation under non-thermal equilibrium cold environment.The correlation between local thermal sensation and local skin temperatures shows that thermal sensation is closely related to skin temperature.Skin temperature is an effective indicator of thermal sensation.A linear relationship model between overall thermal sensation and mean skin temperature,considering both ambient temperature and exposure time,was established in the non-thermal equilibrium cold environment,which makes the evaluation of thermal sensation more objective.

Humanistic caring:the core of nursing

The voice of calling for humanistic concern is always from uncountable doctor-patient conflicts, from which we often hear a doctor is killed or injured for disputes. Prejudice has been rooted in mind that all doctors and nurses are interest-centered and cold-blooded. To some extent, it's true that patterned questions with a poker face are always more than gentle words with warm smile. Nurses are the ones who keep patients company for the longest time. Therefore, caring matters more for them. The explicit concept of "caring" will be introduced and we will attach great importance to how nurses can achieve caring. From the following aspects:the practices of loving kindness, the instillation of faith and hope, sensitivity to indicators of disease, improvem ent of healing environment, communication arts etc, you will understand why nurse is the symbol of angel. We can begin with caring about people around us. Our duty is not only to deal the ill but to warm the chill.

Autoignition of butanol isomers/n-heptane blend fuels on a rapid compression machine in N_2/O_2/Ar mixtures

Ignition delay times of butanol isomers/n-heptane mixture were measured using a rapid compression machine at compressed pressures of 15,20 and 30 bar,in the compressed temperature range of 650–830 K and equivalence ratio of 1.0.Sensitivity analysis and reaction fluxes analysis were performed using a detailed mechanism of blend fuels so as to evaluate the impact of n-heptane addition and temperature variation on the ignition and combustion process.Over the experimental conditions in this study,the blend fuels displays apparent low and high temperature reactions and a negative-temperature-coefficient(NTC)behavior.With increasing butanol isomers mole fraction in the mixtures,the ignition delay times increase.It is worth noting that the suppression to n-heptane ignition from tert-butanol is very limited.The ignition delay time of 40/60 tert-butanol/n-heptane mixture is smaller than other three kinds of blends.With the increasing of tert-butanol mole fraction,the increasing range of its ignition delay time is very large.Moreover,compressed pressure has a limited effect on the ignition of blend mixture at low temperature but certain influence at medium temperature arrange.Tert-butanol/n-heptane mixture is not sensitive to the pressure.The chemical analysis indicates that butanol isomers also present the NTC behavior because of the low temperature reactivity radicals pool produced by n-heptane.Reaction fluxes analysis shows that the n-heptane addition has little impact on the reaction path.Sensitivity analysis shows that for the pure n-butanol,2-butanol and iso-butanol fuel,H-abstraction from the?-carbon plays the dominant role in the reactions having the inhibiting effect on the low-temperature branching,while the H-abstraction from the?-carbon can promote the ignition;for tert-butanol/n-heptane mixtures,reaction R16.H2O2(+M)<=>OH+OH(+M)plays the leading role.For n-butanol/n-heptane,iso-butanol/n-heptane mixtures,the major promoting reactions include some H-abstraction from n-heptane and OH branching reactions,the influence of H-abstraction from?-carbon is weaken;For 2-butanol/n-heptane,tert-butanol/n-heptane mixtures,R16 plays an absolutely dominant role,while the major inhibiting reactions add some elementary reactions of small radicals.