The multiple-scale averaging and dynamics of dispersion-managed optical solitons

Multiple-scale averaging is applied to the nonlinear Schrödinger equation with rapidly varying coefficients, and use the results to analyze pulse propagation in an optical fiber when a periodic dispersion map is employed. The effects of fiber loss and repeated amplification are taken into account by use of a coordinate transformation to relate the pulse dynamics in lossy fibers to that in equivalent lossless fibers. Second-order averaging leads to a general evolution equation that is applicable to both return-to-zero (soliton) and non-return-to-zero encoding schemes. The resulting equation is then applied to the specific case of solitons, and an asymptotic theory for the pulse dynamics is developed. Based upon the theory, a simple and effective design of two-step dispersion maps that are advantageous for wavelength-division-multiplexed soliton transmission is proposed. Theuse of these specifically designed dispersion maps allows simultaneous minimization of dispersive radiation in several different channels.     

Multisoliton complexes in fiber lasers

The formation of stationary and non-stationary pulse groups is regularly observed in multiple pulse soliton fiber lasers. The environment developed in this study for the flexible investigation of this phenomenon is based on the cavity comprising a semiconductor saturable absorber mirror (SESAM) with complex dynamics of absorption recovery and all-fiber dispersion management. The detailed experimental and theoretical considerations show that multiple pulsing in fiber systems offers numerous embodiments ranging from stationary bound states to chaotic bunches. The pulse interaction through the dispersive waves was found to produce a principal impact on the bound state formation. The stability and transformation of stationary bound states and bunch propagation have been also addressed.     

温度对天然块矿爆裂的影响

 天然块矿的爆裂指标作为评价矿石最重要的指标之一,其好坏会直接影响高炉的透气性,进而影响高炉顺行。对天然块矿爆裂性能的研究,有利于为合理搭配入炉炉料结构提供相应的依据。研究了4种天然块矿在不同温度下的爆裂性能,以及天然块矿爆裂性能的主要影响因素。试验表明：随着温度的不断升高,4种天然块矿爆裂后的粒级分布以及爆裂指数呈现不同的变化规律,而不同类型的天然块矿在同一温度下的爆裂指数也不尽相同。天然块矿中羟基的质量分数越高,其爆裂性能越强烈。块矿孔隙总体积和微孔平均直径的减小也会导致块矿的爆裂性能升高。     

Multi-symplectic integration of coupled non-linear Schrödinger system with soliton solutions

Systems of coupled non-linear Schrödinger equations with soliton solutions are integrated using the six-point scheme which is equivalent to the multi-symplectic Preissman scheme. The numerical dispersion relations are studied for the linearized equation. Numerical results for elastic and inelastic soliton collisions are presented. Numerical experiments confirm the excellent conservation of energy, momentum and norm in long-term computations and their relations to the qualitative behaviour of the soliton solutions.     

静压铸造生产线落砂、清理常见问题及对策

文章简述了静压铸造生产线落砂、清理工部的特点,介绍了静压铸造生产线落砂、运输和清理时经常出现的块砂、芯砂混入、铸件磕碰等问题及其解决办法。为使静压线正常运行,必须重视产品铸造工艺设计以及落砂和清理等后处理工序对生产线运行的影响。从工艺设计入手,采取合理的落砂和输送布局;采取与生产线相适宜的铸造工艺,尤其是制芯工艺,减少清理工作量;从铸件生产的流程考虑,采取合理的清理方式,使用高效的清理设备。     

高性能混凝土中再生骨料的应用

为了利用废弃混凝土块形成的再生骨料代替天然碎石等粗骨料配制再生高性能混凝土，针对再生骨料的自身特性以及高性能混凝土本身对骨料的要求，提出了一些可行的方法来改善再生骨料自身缺陷以达到制备高性能混凝土的要求。     

基于SPH方法的大块煤冲击破碎数值模拟

为研究大块煤在钎杆冲击下的破碎效果,引入RHT混凝土本构模型材料来模拟大块硬煤（压缩强度35 MPa）,并基于光滑质点流体动力学（SPH）方法建立了钎杆冲击大块煤的三维仿真模型。分析比较了大块在静压、纯冲击和冲压组合作用下的破坏程度,以及平头和圆锥形钎杆冲击效果的差异。仿真结果表明：平头钎杆在30 MPa压力、15 m/s速度或是其组合作用下,均无法使大块产生有效破坏;平头钎杆在200 m/s的超高速下可使大块产生彻体破坏,但实现钎杆高速运动困难;圆锥钎杆在30 MPa压力和15 m/s速度的冲压作用下,使大块产生了较大范围的锥形失效,远高于常规液压破碎锤的单次冲击破坏程度。锥形钎杆、高压高速是破碎硬质大块煤的一种有效方法,可在较少作用次数下实现破碎,验证了低频重载破碎大块的可行性。     

中硬煤层块煤率提高技术

为了提高中硬煤层综采工作面的块煤率,根据矿井的地质条件及设备选型,从开采工艺和装备两方面进行了研究。采用微差爆破技术对工作面煤壁进行了弱化;对采煤机参数进行了优化,并采用数值模拟方法进行校验。研究结果表明:采用煤层弱化与采煤机参数优化相结合的技术措施后,井下工作面的块煤率提高了4.34%,地面块煤率提高了8.59%,块煤率得到了明显提高,给煤矿带来了显著的经济效益。     

提高炮采块煤率技术体系研究与应用

为了提高矿井综合块煤率,系统研究了影响块煤率的因素,认为优化爆破方案、减少块煤在运输诸多环节中损失是提高块煤率的关键。依据百善煤矿原煤的性质和特点,提出了松动预裂微差爆破的落煤方案,并对布孔参数和爆破参数进行了优化。针对块煤在运输转载环节损失严重的情况,提出了无落差平行转载技术和螺旋煤仓缓冲溜煤技术,阐述了其防破碎原理、结构和设计参数,并进行了试验研究。实践表明：松动预裂微差爆破技术可有效减小对煤体的破碎,提高块煤产出率;无落差平行转载技术和螺旋煤仓缓冲溜煤技术,大幅减少了块煤在运输转载环节中损失,基本达到了块煤的零破碎。     

提高炮采工作面块煤率的技术途径

为提高小煤矿炮采块煤率,结合龙岩矿区小煤矿块煤层特征,分析了块煤率的影响因素为块煤的岩性特征和爆破落煤方式,基于块煤岩性特征将块煤分为3类块煤,为提高块煤率研究分析了这3类块煤开采选择不同的落煤方式。试验结果表明：坚硬块煤层可通过适当爆破落煤方式实现块煤率提高23％;节理发育条带块煤层,可不放炮直接采用风镐落煤法开采,其块煤率提高33％;块煤夹粉煤煤层,采用爆破振动加风镐落煤的方法,块煤率提高较多。