Temperature Sensitivity Control and Mechanical Stress Effect of Boron-Doped Long-Period Fiber Gratings

We will present in this work the quantitative analysis of the relationship between the doping concentrations of GeO 2 and B 2 O 3 in the core and cladding regions and the temperature sensitivity of the resonance wavelength shift in long-period fiber gratings (LPFGs). Based on this analysis, the temperature sensitivity was suppressed and enhanced to 0.002 nm/C and 0.28 nm/C, respectively. We will also discuss the effect of the residual mechanical stress on the optical and mechanical properties of LPFGs. In particular, we will present the measurement results of the dependence of the refractive index change and mechanical strength on the residual mechanical stress in the boron-doped fibers with depressed clad and matched clad.     

Temperature Sensitivity Control and Mechanical Stress Effect of Boron-Doped Long-Period Fiber Gratings

We will present in this work the quantitative analysis of the relationship between the doping concentrations of GeO 2 and B 2 O 3 in the core and cladding regions and the temperature sensitivity of the resonance wavelength shift in long-period fiber gratings (LPFGs). Based on this analysis, the temperature sensitivity was suppressed and enhanced to 0.002 nm/°C and 0.28 nm/°C, respectively. We will also discuss the effect of the residual mechanical stress on the optical and mechanical properties of LPFGs. In particular, we will present the measurement results of the dependence of the refractive index change and mechanical strength on the residual mechanical stress in the boron-doped fibers with depressed clad and matched clad.     

Flattening of sheet metal by laser forming

Laser forming is a thermal process for deformation of sheet metal by thermal stress. In this paper, the technique of laser forming is applied to flatten a protruded distortion on the sheet metal, and the mechanism of flattening is investigated experimentally. The protrusion of some height is intentionally produced by pressing a steel ball on a flat sheet metal. The laser beam was irradiated at the area of distortion, and as a result, the protrusion disappeared and an almost flat sheet metal could be obtained.     

Representability of Hom implies flatness

LetX be a projective scheme over a noetherian base schemeS, and letF be a coherent sheaf onX. For any coherent sheaf ε onX, consider the set-valued contravariant functor Hom(ε,F)S-schemes, defined by Hom(ε,F) (T)= Hom(ε _T ,F _T) where ε _T andF _T are the pull-backs of ε andF toX _T =X x _S T. A basic result of Grothendieck ([EGA], III 7.7.8, 7.7.9) says that ifF is flat over S then Kom_ε,F) is representable for all ε. We prove the converse of the above, in fact, we show that ifL is a relatively ample line bundle onX over S such that the functor Hom(L ^-n ,F) is representable for infinitely many positive integersn, thenF is flat overS. As a corollary, takingX =S, it follows that ifF is a coherent sheaf on S then the functorT ↦H°(T, F _t) on the category ofS-schemes is representable if and only ifF is locally free onS. This answers a question posed by Angelo Vistoli. The techniques we use involve the proof of flattening stratification, together with the methods used in proving the author’s earlier result (see [N1]) that the automorphism group functor of a coherent sheaf onS is representable if and only if the sheaf is locally free.     

Relationship between particle size and deformation in the cold spray process

The flattening of aluminum and copper particles cold sprayed onto ceramic surfaces has been described by an ellipsoidal function. The accuracy of this approximation was verified from particle dissections performed in a focused ion beam/scanning electron microscope (FIB/SEM). Flattening data were collected from SEM measurements. It was shown that aluminum particle deformation was limited below ∼5 μm, and copper deformation below ∼2 μm. Deceleration of the particles through the bow shock, strain rate hardening and thermal conduction were factors that contributed to the differences in deformation behaviour.     

Properties of Physical Systems: Transient Singularities on Borders and Surface Transitive Zones

Certain alternative properties of physical systems are describable by supports of arguments of response functions (e.g. light cone, borders of media) and expressed by projectors; corresponding equations of restraints lead to dispersion relations, theorems of counting, etc. As supports are measurable, their absolutely strict borders contradict the spirit of quantum theory and their quantum evolution leading to appearance of subtractions or certain needed flattening would be considered. “Flattening” of projectors introduce transitive zones that can be examined as a specification of adiabatic hypothesis or the Bogoliubov regulatory function in QED. For demonstration of their possibilities the phenomena of refraction and reflection of electromagnetic wave are considered; they show, in particular, the inevitable appearing of double electromagnetic layers on all surfaces that formerly were repeatedly postulated, etc. Quantum dynamics of projectors proves the neediness of subtractions that usually are artificially adding and express transient singularities and zones in squeezed forms.     

激光周向探测小型化发射技术

针对小口径弹药用脉冲激光周向探测系统的小体积和轻质量的设计难点,在全面分析脉冲激光周向探测系统的基础上,提出了采用激光发射系统解体分离技术和光学系统扁平化技术实现脉冲激光周向探测系统小型化的解决方案.将传统、较大尺寸、一体化结构的激光发射系统的激光器与激光器驱动电源进行结构分离,达到轴向尺寸压缩的目的,并利用灌封技术进行抗过载处理;选择平凸球面单透镜光学元件代替非球面透镜,经过理论计算和光学系统仿真,设计出扁平化激光准直系统,有效压缩轴向尺寸.针对结构小型化带来的空间电磁干扰问题,基于磁场屏蔽机理,采用特殊结构屏蔽体,有效抑制了电磁干扰.加工制作了原理样机并进行了目标探测试验.实验结果表明:样机能有效探测近程目标,且脉冲激光周向探测系统的有效尺寸显著减小,验证了小型化技术的可行性和实用性.