简介:通过对三相四线系统零线运行故障的分析,发现三相四线中的零线因故断路后,在三相负载不对称时,则会产生变压器中性点位移,致使三相电压不平衡,即有的相电压过高,可能烧毁电器设备,有的相电压过低,使电器设备无法正常使用。为了防止此类故障的发生,通过试实验研究,提出了具体可行的预防措施,以供实际工作中参考.
简介:OnMarch26,2010anunderwaterexplosion(UWE)ledtothesinkingoftheROKSCheonan.TheofficialMultinationalCivilian-MilitaryJointInvestigationGroup(MCMJIG)reportconcludedthatthecauseoftheunderwaterexplosionwasa250kgnetexplosiveweight(NEW)detonationatadepthof69mfromaDPRK'CHT-02D'torpedo.KimandGitterman(2012a)determinedtheNEWandseismicmagnitudeas136kgatadepthofapproximately8mand2.04,respectivelyusingbasichydrodynamicsbasedontheoreticalandexperimentalmethodsaswellasspectralanalysisandseismicmethods.ThepurposeofthisstudywastoclarifythecauseoftheUWEviamoredetailedmethodsusingbubbledynamicsandsimulationofpropellersaswellasforensicseismology.Regardingtheobservedbubblepulseperiodof0.990s,0.976sand1.030swerefoundincaseofa136NEWatadetonationdepthof8musingtheboundaryelementmethod(BEM)and3Dbubbleshapesimulationsderivedfora136kgNEWdetonationatadepthof8mapproximately5mportsidefromthehullcenterline.Hereweshowthroughanalyticalequations,modelsand3Dbubbleshapesimulationsthatthemostprobablecauseofthisunderwaterexplosionwasa136kgNEWdetonationatadepthof8mattributabletoaROKlittoral'landcontrol'mine(LCM).
简介:目的:调查我院对外合作办学2013级新生入校时心理健康素质和大学生活适应状况,并对比单招生和统招生的差异,为学生工作提供依据。方法:随机整群抽取我院对外合作办学2013级新生780名,在新生入校初进行《大学生心理健康素质》和《大学新生适应量表》问卷测评。结果:单招生的情绪调控维度上的得分显著低于统招生,统招生在目标追求维度上的得分显著低于单招生。统招生整体大学生活困扰、独立生活困扰和人际关系困扰程度显著高于单招生。结论:单招生的情绪调控能力更差,发生打架闹事等违纪现象的概率会更高。而统招生普遍对本专业认知不清、目标模糊。单招新生更适应大学生活,尤其是独立生活困扰不大,与人交往也更得心应手。