两管的

The formation mechanism of the absolute instability and gyrotron backward wave oscillations is analyzed, and the methods to suppress the parasitical modes are discussed.The nonlinear theory model of gyro-TWT is consummated by considering the influence of tapered magnetic field and waveguide radius, electron velocity spread, and waveguide loss on electron beam-wave interaction. The large-signal characteristic of gyro-TWT, such as launching loss and absolute instability, are also analyzed in detail. This work establishes the foundation for the development of a gyro-TWT amplifier.

重点研究了两段损耗波导结构和损耗陶瓷结构回旋行波管中的电子注-波互作用，分析了绝对不稳定性和回旋返波振荡的形成机制和抑制寄生模式的方法；完善了回旋行波管的非线性理论模型，并考虑了磁场和波导半径渐变、速度零散、波导损耗等因素对注-波互作用的影响；详细分析了发射损耗、相位稳定性等回旋行波管的大信号特征，为回旋行波管放大器的研制奠定了基础。

Based on thermodynamics and thermo-acoustics, the effect of the pulse tube structure was analyzed. It was found that the cross sectional area of the pulse tube influence greatly the working fluid pressure and temperature distributions.

结合热力学和热声学两方面的理论，对脉管制冷机中脉管的结构进行了分析，发现脉管的截面积与其内工质压力、温度分布匹配与否，对脉管制冷机的性能有很大影响。

For naturally cooled monobloc barrel, its thermal condition in regular regime can be evaluated by measuring the outside temperature of two arbitrary rounds;(2) During a sustained firing process, unsteady heat conduction exists in a monobloc barrel, whereas unsteady and quasi steady heat conduction exist with actively cooled composite barrels, meaning that the thermal condition changes from uncontrolled to controlled;(3) Different combinations of the convective heat transfer coefficient h and thickness of gun barrel δ have much effects on cooling the bore temperature.

利用有限元软件分析了某大口径火炮身管的温度场分布，并对自然散热条件下的单筒身管和主动冷却条件下的复合身管温度场进行了比较，其结果为(1)身管温度场分布存在初始和正规工况阶段，后者的单筒身管热状态可以通过测定任意两发身管外表面温度来评估；(2)持续射击过程中，单筒身管始终处于非稳态导热过程，主动冷却身管则包括非稳态和准稳态两个过程，实现了身管热状态由不可控向可控转变；(3)对流传热系数h和身管壁厚δ的组合对降低内膛温度具有很大影响。

Aiming at the two structural features of axle shaft sleeve on the basis of analyzing various forming technologies applied in domestic and overseas in recent years,two new hot extrusion forming technology of axle shaft sleeve are worked out.

针对半轴套管的两种结构特点，在分析了国内外近年来所采用的各种成形工艺的基础上，分别开发了用镦粗-反挤压和扩径-正挤压两道复合工序相结合成形分体式半轴套管和用两次复合镦挤的方法成形整体式半轴套管的两种热挤压成形新工艺，通过物理模拟实验证明了成形工艺的可行性、实用性。

Or, rather, it employs two ring-shaped half-pipes that rotate with respect to one another (the lower one remaining fixed while the upper one revolves along with the building). The joints between the half-pipes have rubber seals to stop the contents leaking, and each half-pipe has a vertical pipe connected to it, to introduce or dispose of the fluid concerned.

或者更确切的说，它使用了两根彼此旋转的环形半管（当上面那根独自围着建筑旋转的时候，下面那根余下的部分被固定），两根半管的接头有橡胶防止泄漏，每根半管都有一根垂直管与之相连，引入或排出附着的液体。

Since the turbine-driven feedwater pump failed to regulate directly the drum level of single boiler and problems like pressure overrun of main feedwater pipe existed, DCS was utilized to solve the problems for its features of shared information, powerful configuration functions and easy modification.

在对国电成都热电厂嘉陵2×142MW机组两炉一机单元给水系统控制方式进行分析的基础上，针对运行中出现的汽动给水泵不能直接调节单台锅炉汽包水位及给水母管压力超限等问题，利用分散控制系统信息共享、组态功能强大、修改方便的特点，在不增加硬件设备的情况下，通过软件组态增加了汽动给水泵调节单台锅炉汽包水位调节回路和给水母管超压及欠压保护回路，实现了机组在一炉一机单元运行和两炉一机母管运行2种运行方式下给水自动的合理控制，并解决了给水母管的压力保护问题，提高了机组运行的安全可靠性。

Objective To evaluate clinical effect of the handling ProTaper Nickel-titanium rotary instruments in preparation of canals of posterior teeth.Methods 96teeth with pulpitis or periapical periodontitis were instrumented by handling ProTaper rotary instruments using step-down technique,and by K files using step-back technique for control.All teeth were obturated with lateral condensation methods.The efficiency of preparation was analyzed with ra-diographs before and after operation.

目的 评价手用ProTaper预备后牙根管的临床效果方法选取患有牙髓炎和根尖周炎的后牙96例，随机分成试验组和对照组各48例，试验组用手用ProTaper 锥度镍钛旋转器械逐步伸入法预备根管，对照组用K锉，逐步后退法预备根管，两组均用侧向加压充填法充填根管，根据治疗后的X线片，评价后牙根管预备效果。

objective to evaluate clinical effect of the handling protaper nickel-titanium rotary instruments in preparation of canals of posterior teeth.methods 96teeth with pulpitis or periapical periodontitis were instrumented by handling protaper rotary instruments using step-down technique,and by k files using step-back technique for control.all teeth were obturated with lateral condensation methods.the efficiency of preparation was analyzed with ra-diographs before and after operation.results no transportation,apical blockage and ledge were found in test.the technique could keep canals smooth.there were two ledge,one instrument fracture and nine transportation in control.the operative time was shorter and post treatment pain seldom occurred in handling protaper group.conclusion the handling protaper niti rotary instruments can prepare the canals effectively and safety.after the preparation,the canals could be easily washed,sterilized and filled.it is an efficient instrumentation method for posterior teeth's canals and be used widely.

目的 评价手用protaper预备后牙根管的临床效果。方法选取患有牙髓炎和根尖周炎的后牙96例，随机分成试验组和对照组各48例，试验组用手用protaper多锥度镍钛旋转器械逐步伸入法预备根管，对照组用k锉，逐步后退法预备根管，两组均用侧向加压充填法充填根管，根据治疗前后的x线片，评价后牙根管预备效果。结果试验组无根管偏移、根尖阻塞、台阶，且根管壁平滑流畅，无器械折断等并发症发生。对照组有2例台阶形成，器械折断1例，根管偏移9例。试验组操作时间短且术后疼痛轻微。结论应用手用protaper预备后牙根管快速、安全，成形效果好，易于根管冲洗消毒及填充，可视为临床上预备后牙根管的有效方法。

The results showed that the CNTs have outer diameters of about 60 nm~90 nm and a length of 8 μm, showing straight tubular and chain structures.

结果显示：合成的碳纳米管为多壁碳管；碳纳米管直径60nm~90nm，长度约8μm；碳纳米管展现出中空管状和链状两种结构；碳纳米管的生长采取催化剂底端生长模式。

During past 2 years, we produced milkly white fused quartz tubing, non-ozone quartz tubing, UV stop quartz glass tubing, sunshine quartz tubing on the basis of common quartz tubing, they are widely used in electric industry, electric lamp-house, chemical, nuclear industry, etc, and won users'trust and favorable comments .Our co. also holds advanced full analyse and finished product and detect system. The 2 sets of infrared photometers have being used in the process of producing, and control effectively the content of hydroxy in the quartz products.

公司成立两年多来，在生产普通石英管的基础上，相继推出乳白石英管、无臭氧石英管、滤紫外线石英管、以及太阳光石英管等，广泛用于电子工业、电光源、化学、核工业等领域，深受用户的信赖和好评。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。