共查询到20条相似文献,搜索用时 93 毫秒
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在现在的发展中,各项工作都需要在先进的科学技术的支持下更好的开展相关的工作计量质量检验检测工作的进行对我们的工作有很大的帮助,面向未来,就要求我们在先进的技术的指导下更好的开展相关的工作。我们自身的发展还不够完善,根据实际的发展需求不断地做好相关的工作,这样才能达到更高的发展水平,随着现代化进程的加快,我们就更需要做好自己的工作,达到发展的目标。 相似文献
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随着时代的进步和高速的发展,各国的能源问题也被逐渐的提上日程。本文就世界能源的现状还有内燃机的发展进行相应的论述,提出相应的看法和亟待解决的措施。对中国的能源发展提出相应的看法,希望能走出一个适合中国国情的一条特色的道路。 相似文献
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随着时代的发展,经济的增长,社会的进步,我国的综合国力逐渐提高,科学技术不断的改良、创新、进步,而这些改变随之而来的是我国的工业发展越来越迅速,以往的封建的旧的思想以及旧的技术、产品已近满足不了这个时代的需求,人们的生活水平不断提高,对于新兴的产品以及技术的需求越来越高,超声振动辅助钻削钛合金技术的发展就是其中之一。 相似文献
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从古至今,我国的农业取得很大的发展,已基本实现自动化,作为其中最重要的经济作物之一的玉米,在其中的地位非常重要。玉米在一定程度上不但为我国的经济发展做出了相应的贡献,另外在人们的日常饮食以及生产当中的作用也十分巨大,因此将玉米高产栽培技术的推广工作做好具有非常深远的意义。然而通过对广大玉米产地进行的实际调查研究发现,在具体的推广高产栽培技术的的时候,依然有许多问题对提高玉米的生产效益造成了很大的困扰。下面我们就将对此进行简单的分析,并有针对性的提出相应的解决措施,希望能够对我国农业的发展起到借鉴和参考的作用。 相似文献
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预应力混凝土管桩的生产过程,其中预应力是对管桩抗弯性能的一个最重要的参数,预应力的施加是由一台张拉机的设备来控制,以前采用传统的标尺来控制管桩长度的拉伸量,员工观看标尺刻度到达规定的标准值时,人手控制停止的方式来决定一条管桩的预应力,这样对操作员工的要求较高(不同管桩的长度的拉伸值要相应的改变),控制产品的精度差,产品的质量得不到保证。针对生产现场的实际情况,合理设计张拉机的全自动控制系统,对员工操作的要求降低,全自动控制系统精度得到保证,从而保证产品质量的稳定,提高公司的生产效益。 相似文献
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This paper presents the design of a small-scale nanopositioner, the μHexFlex, which is comprised of a six-axis compliant mechanism and three pairs of two-axis thermo-mechanical micro-actuators. In this paper, we cover the modeling, design and fabrication of the μHexFlex. Specific attention is given to: (1) the use of constraint-based design in generating the compliant mechanism design, (2) the modeling of the actuators, and (3) the system model which links the actuator input and mechanism response. The measured, quasi-static performance of a 3 mm diameter prototype shows a maximum range of 8.4 μm × 12.8 μm × 8.8 μm and 19.2 mrad × 17.5 mrad × 33.2 mrad (1.1° × 1.0° × 1.9°). Experimental results indicate that a constant mechanical/electrical material property system model may be used to predict the position and orientation over a range of 3.0 μm × 4.4 μm × 3.0 μm and 6.3 mrad × 6.3 mrad × 8.7 mrad (0.36° × 0.36° × 0.5°). The dynamic characteristics of the device were investigated experimentally. Experimental results show a lowest natural frequency of 4 kHz. The resolution characteristics of the device have been measured at 1 Å/mV. The device was created using deep reactive ion etching (DRIE). Bulk fabrication costs are estimated at less than $ 2 per device. 相似文献
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Wear variations of Nimonic 80A slid against Incoloy 800HT between room temperature (RT) and 750 °C, and sliding speeds of 0.314 and 0.905 m s−1 were investigated using a ‘reciprocating-block-on-cylinder’, low debris retention configuration. These were considered alongside previous observations at 0.654 m s−1.Different wear types occurring were mapped, including high transfer ‘severe wear’ (RT and 270 °C, also 0.905 m s−1 at ≤570°C), low transfer ‘severe wear’ (0.314 m s−1 at 390 °C to 510 °C oxide abrasion assisted at 510 °C), and ‘mild wear’ (0.314 m s−1 at ≥570 °C; 0.905 m s−1 at ≥630 °C). Wear surfaces at 750 °C were cross-sectioned and profiled. 相似文献
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Patrice Salzenstein Nathalie Cholley Alexander Kuna Philippe Abbé Franck Lardet-Vieudrin Ludvík Šojdr Jacques Chauvin 《Measurement》2012
The aim of this communication is to present the performances of 5 MHz distributed ultra-stable system, based on ultra-stable Boitiers à Vieillissement Amélioré (BVA) oscillator. We demonstrated flicker frequency modulation (FFM) floor better than 4.5 × 10−14 ± 2.5 × 10−15 at 12 s with an intrinsic noise floor about 6 × 10−15 at 1 s with a τ−1/2 time integration dependence slope. 相似文献
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The kinematics, stiffness, and repeatability of a moving groove, dual-purpose positioner-fixture were determined experimentally. A dual-purpose positioner-fixture is an alignment device that may be operated in a fixture mode or a six-axis nanopositioning mode. When operated in fixture mode, experiments show standard deviation in repeatability of 11, 11, and 38 nm in x, y, and z; and 0.7, 0.3, and 0.3 μrad in θx, θy, and θz. The stiffness characteristics were shown to match predictions within 5%. When operated in nanopositioner mode, the device demonstrated 4 nm resolution and a range, of 40 μm × 40 μm × 80 μm in translation and 800 μrad × 800 μrad × 400 μrad in rotation. The fixture possesses a load capacity of 450 N and a natural frequency of 200 Hz when the fixture is preloaded to 225 N. 相似文献
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Density functional theory, as implemented in a full-potential linearized augmented plane wave method, flair, is used to calculated the pressure-dependent shear strength S of KCl on a Fe(100) substrate and the results are compared to the experimental dependence given by S = S0 + aP S = S_{0} + \alpha P , where P is the contact pressure and S
0 = 65 ± 5 MPa and α = 0.14 ± 0.02. Calculations were performed for a KCl bilayer enclosed between two Fe(100) slabs, where the energy was found
to vary harmonically as a function of the separation between the outermost layers. Thus, a simple analytical model was developed
for the pressure-dependent shear strength of the film, which includes both linear and quadratic pressure dependence. However,
the coefficient of the quadratic term was found to be much smaller than the linear term, leading to the linear shear-strength
pressure dependence found experimentally. The calculated values of S
0 〈10〉 = 64 ± 9 and S
0 〈11〉 = 69 ± 8 MPa are in excellent agreement with experiment, while α 〈10〉 and α 〈11〉 equal 0.05 ± 0.01, somewhat lower than,
but within the same range as the experimental values. 相似文献
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This paper is a supplement to “Trends in the Development of Advanced Manufacturing Technology” (Yang and Wu in Chin. J. Mech. Eng., 39: 73, 2003) but delves deeper into it. It first points out the strategic status of manufacturing industry in state development. Then,
a detailed analysis is given on the features and trends in the development of advanced manufacturing technology in a total
of 12 points from three aspects: “precision,” “extreme,” and “culture” from the aspect of the product itself; “green,” “rapidness,”
“saving,” and “efficiency” during the manufacturing process; and “digit,” “auto,” “integration,” “networking,” and “intelligence”
in view of the manufacturing method. In addition, it emphasizes that all the above aspects should be based on two base points:
“manufacture” and “machinery.” Finally, it puts forth the guiding ideologies for the development of advanced manufacturing
technology and the aspects China should give priority to in development, while stressing on the principles of independence,
innovation and “human orientation.” 相似文献
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The results of the upgrading of P-48 and P-49 spark-gap switches that allowed us to improve their electric performances are
presented. The design and performance data of РИМ 100/35 and РИМ 200/50 gas-filled metal-ceramic spark-gap switches are described.
When used in the circuit of the Marx generator of the APCA accelerator operating at a voltage-rise time of 5–6 μs, they ensure
a pulsed breakdown voltage of 120 and 150 kV, respectively. In such devices as МИРА, ДИНА, etc., operating at a voltage-rise
time of 0.5–1 μs, the breakdown voltage of these spark-gap switches can be increased up to 130 kV (for РИМ 100/35) and 220
kV (for РИМ 200/50). The intrinsic switch time is <0.5 ns. Some practical recommendations for the metal-ceramic spark-gap
switch design are provided. 相似文献
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V. V. Rashchenko 《Instruments and Experimental Techniques》2012,55(1):49-55
A ГИД-25 pulse generator with a 25-J capacitive storage is designed as a pulse power source of lenses and correctors of transportation
channels of electron and positron beams from the storage-cooler of the ВЭПП-5 injector system to booster storages of the ВЭПП-4
and ВЭПП-2000 systems. The generator consists of a 100-μF storage capacitor, a charging unit, and a thyristor switch, which
switches the capacitor to the load. The generator ensures the precision charging of the storage capacitors up to 15–700 V
of any polarity and switching it to the winding of the magnetic element of the channel. The capacitor charging error is ≤0.01%
in all working voltage range. The pulse repetition rate is 1 Hz. 相似文献