Temperature Responses to External Heat Fluxes of the Power Distribution System on Alpha Magnetic Spectrometer

High-temperature warnings frequently occurred at the Power Distribution System(PDS)of the Alpha Magnetic Spectrometer(AMS).To investigate the fundamental reasons,a theoretical model for the AMS PDS was established under the International Space Station(ISS)normal and special operating conditions.With the model,the study investigated the external heat fluxes and the temperature responses of the PDS.The effects of ISS special operations on the PDS’s thermal environment were also investigated.Results reveal that the total external heat flux at the PDS reaches its maximum value when the angleβis around–25°,where high-temperature warning frequently occurs.Under the ISS normal operating condition,the temperature response hysteresis at the PDS varies from 116 s to 230 s.When the ISS performed special operations,locking the ISS solar arrays had the greatest influence on the PDS’s external heat fluxes,and the average temperature at the PDS fell by 1.7°C.When the ISS performed multiple special operations,simultaneously locking the ISS solar arrays and adjusting the ISS flight attitude were the most frequent operations,of which the influences on the PDS temperature were the largest,i.e.,the changes in peak temperature reached up to+2.5°C.

Structure dependence of magnetic properties in yttrium iron garnet by metal-organic decomposition method

The yttrium iron garnet（YIG） samples are prepared at different temperatures from 900℃ to 1300℃ by the metalorganic decomposition（MOD） method. The chemical composition and crystal structure of the samples are studied by scanning electron microscope（SEM）, XRD, and Mossbauer spectrometer. It is shown that the ratio of ferric ions on two types of sites, the octahedral and the tetrahedral, is increased with the sintering temperature. At 1300℃, the pure garnet phase has been obtained, in which the ferric ions ratio is 2：3 leading to the minimum magnetic coercivity and maximum saturation magnetization. These results provide a route to synthesize pure YIG materials as the basic materials used in various spintronics applications.

Measurment of the energy spectrum of an electron beam extracted from an accelerator

The electron energy spectrum is one of the most important characteristics of an electron beam that is extracted from a linear accelerator. The most direct way to determine an electron spectrum would be to use a magnetic spectrometer and this method could also give results with high precision and effectiveness. In this article we describe our design of a new multi-layer absorption method, which is based on the depth-dose curves method that can be used in most irradiation accelerators, and adds the Monte Carlo simulation and iterative algorithm in order to reconstruct the electron energy spectrum. In this article the energy spectrum was measured using these two methods, and good results were acquired. These results could be crosschecked, which made the results more reliable.

Operation characteristics of AMS-02 loop heat pipe with bypass valve

Loop heat pipes （LHPs） were designed for the alpha magnetic spectrometer （AMS-02） to dissipate heat from the cryocoolers. A bypass valve is applied to the LHP to keep the cryocooler temperature above its limit （-20℃） in cold environment. Extensive experiments were performed on operation characteristics of LHPs with the bypass valve for AMS-02 during thermal vacuum and thermal balance （TVTB） test. We found that the bypass valve can start up successfully in cold environment. With the bypass valve, the evaporator temperature is stable and can meet the requirement of the cryocooler. We analyzed three operating modes of the bypass valve. Set point temperature and regulation temperature shifts were observed and their relations with the bypass valve temperature were given.

Prediction of Metabolic Disorders Using NMR-Based Metabolomics:The Shanghai Changfeng Study

A metabolically healthy status,whether obese or not,is a transient stage with the potential to develop into metabolic disor-ders during the course of life.We investigated the incidence of metabolic disorders in 1078 metabolically healthy Chinese adults from the Shanghai Changfeng Study and looked for metabolites that discriminated the participants who would develop metabolic disorders in the future.Participants were divided into metabolically healthy overweight/obesity(MHO)and meta-bolically healthy normal weight(MHNW)groups according to their body mass index(BMI)and metabolic status.Their serum metabolomic profile was measured using a ^(1)H nuclear magnetic resonance spectrometer(^(1)H-NMR).The prevalence of diabetes,hypertriglyceridemia,hypercholesterolemia and metabolic syndrome was similar between the MHNW and MHO participants at baseline.After a median of 4.2 years of follow-up,more MHO participants became metabolically unhealthy than MHNW participants.However,a subgroup of MHO participants who remained metabolically healthy(MHO→MHO)had a similar prevalence of metabolic disorders as the MHNW participants at the follow-up examination,despite a signifi-cant reduction in their serum concentrations of high-density lipoprotein(HDL)and an elevation in valine,leucine,alanine and tyrosine.Further correlation analysis indicated that serum intermediate-density lipoprotein(IDL)and very low-density lipoprotein cholesterol(VLDL-CH)might be involved in the transition from metabolically healthy to unhealthy status and could be valuable to identify the MHNW and MHO with increased metabolic risks.