Yuntian Yang

The porous-media-based electrospray thruster is a cutting-edge micropropulsion technology that can revolutionize the capabilities of microsatellites. This paper reports the design, fabrication, and characterization of a novel porous-media borosilicate glass electrospray thruster. The porous glass used here is integrally formed by the phase separation method, which make it display outstanding pore uniformity and processability. The picosecond ultraviolet laser processing technique is applied to machine 361 emitters out of glass. Performance characteristic experiments are conducted with the thruster passively fed with ionic EMI-BF4 liquid. The results reveal that the per-emitter can emit up to 200.46 nA of ion current at 2 kV. The novel porous glass and the corresponding machine method present an opportunity to attain more-controllable emitter shapes, which has a positive impact on thruster lifetime and performance improvement.

This work describes the advances on a micro-newton torsional thrust balance for ionic liquid electrospray thruster (ILET) being developed in the National University of Defense Technology. The torsional thrust balance adopts an asymmetric pendulum arm about a flexural pivot, and an electrostatic comb device is used for calibration, which makes the balance compact and allows the measurement of the micro-newton level thrust with high accuracy. To minimize the influence of gravity on the measurement results, a two-dimensional adjustable counterweight mechanism is adapted to balance the entire arm and make its mass center close to the pivot axis. Mechanical oscillations are passively damped with an eddy current damper. A series of experimental studies are carried out in a vacuum chamber; the results provide validation that the balance has good linearity in the range of 2–30 μN, with the resolution better than 0.21 μN and the settling time to a step force is less than 7 s, which can meet the thrust measurement requirements of the ILET operating in the mode of alternating work voltage polarity. In addition, we find that the electrostatic force generated by the power supply wire has a non-negligible influence on thrust measurement results, which needs to be considered in the actual thrust measurement.

Let R=⊕i≥0Ri be a Noetherian commutative nonnegatively graded ring such that (R0,m0) is a Henselian local ring. Let m be its unique graded maximal ideal m0+⊕i>0Ri. Let T be a module-finite (noncommutative) graded R-algebra. Let Tgrmod denote the category of finite graded left T-modules and M∈Tgrmod. Then the following are equivalent: (1) Mˆ is an indecomposable Tˆ-module, where (−)ˆ denotes the m-adic completion; (2) Mm is an indecomposable Tm-module; (3) M is an indecomposable T-module; and (4) M is indecomposable as a graded T-module. As a corollary we prove that for two finite graded left T-modules M and N, the following are equivalent: (1) If M=M1⊕⋯⊕Ms and N=N1⊕⋯⊕Nt are decompositions into indecomposable objects in Tgrmod, then s=t, and there exist some permutation σ∈Ss and integers d1,…,ds such that Ni≅Mσi(di), where −(di) denotes the shift of degree; (2) M≅N as T-modules; (3) Mm≅Nm as Tm-modules; and (4) Mˆ≅Nˆ as Tˆ-modules. As an application, we compare the FFRT property of rings of characteristic p in the graded sense and in the local sense.

The porous-media based electrospray thruster is a cutting edge micro propulsion technology that can revolutionize the capabilities of NanoSats. This paper reports the design, fabrication, and characterization of a porous-media borosilicate glass electrospray thruster. The picosecond infrared laser processing technique is applied to machine 81 emitters out of porous-media. Performance characteristic experiments are conducted with the thruster passively fed with ionic liquid EMI-BF4. The results reveal that the per emitter can emit up to 1.27μA at 2kV. The corresponding machine method present an opportunity to attain more controllable emitter shapes, which has a positive impact on thruster lifetime and performance improvement.

记述采自中国内蒙古和宁夏贺兰山危害青海云杉的扁蜂科一新种:烟翅腮扁蜂 Cephalcia infumata Zhang & Wei，sp.nov.。本种与贺兰腮扁蜂 Cephalcia alashanica(Gussakovskij，1935)和马氏腮扁蜂 C.masuttii Battisti & Boato，1998 近似，3种扁蜂的幼虫均在云杉嫩枝上用虫粪做成显著的虫巢。烟翅腮扁蜂与贺兰腮扁蜂的区别:翅深烟褐色; 雌虫各足股节背侧部分淡色，腹侧大部黑色; 雌虫后眶中下部无后颊脊; 两性触角第3节长于第4+5节之和，长于复眼长径; 雄虫阳茎瓣内顶角近方形等。烟翅腮扁蜂与马氏腮扁蜂的区别:翅深烟褐色; 中胸背板侧叶全部和后小盾片、雄虫小盾片、两性腹部1-6背板大部、雌虫各足股节腹侧大部黑色; 两性触角窝侧区的上侧3/5具刺毛和粗大刻点，下侧2/5无刺毛、无刻点; 触角通常26节; 雄虫阳茎瓣无臀角等。烟翅腮扁蜂与贺兰腮扁蜂COⅠ序列的K2P距离为5.2%。