Electric field sensing with a hybrid polymer/glass fiber

We demonstrate the operation of an in-fiber electric field sensor. The sensor is fabricated with selective chemical etching of the core of a D-shaped optical fiber followed by the deposition of an electro-optic polymer (PMMA/DR1), which forms a hybrid core. The device demonstrates electromagnetic field sensitivity less than 100 V/m at a frequency of 2.9 GHz. Epi is estimated to be 60 MV/m with an insertion loss of 14.4 dB.     

Ultra-High bit rate all-optical AND/OR logic gates based on photonic crystal with multi-wavelength simultaneous operation

In this paper, a novel two-dimensional photonic crystal based all-optical AND/OR logic gates are designed, simulated and optimized. The structure is built on a linear square lattice photonic crystal platform. A multi-wavelength operation, together with a simultaneous operation, is achieved at ultra-high bit rates. The concurrent operation is attained without altering the proposed design continuously, as stated in the literature. It provides simplicity because there is no auxiliary input required along with the absence of externally attached phase shift units. The enhancement process has been done to the rod radius. A magnificent representation tool is developed. The benefit of the mentioned tool lies in the data combination of different operating wavelengths, contrast ratio, and bit rate; which will establish an efficient optimization process. Each gate is enhanced independently, then an overall improvement has been done. As a result, the operation at 1.52?µm will provide a successful multi logic gate operation with ultra-high bit rates of 6.76 and 4.74 Tbit/s for AND and OR logic gates, respectively. The design has an acceptable size of (19.8?×?12.6 µm) and a contrast ratio of 9.74?dB and 17.95?dB for the designed AND and OR gate, respectively. The design is highly sensitive to the waveguide length to verify the gates on demand.     

Resonantly pumped 1.645 μm single longitudinal mode Er:YAG laser with intracavity etalons

We report on a 1.645 μm single longitudinal mode Er:YAG laser that was resonantly pumped by a 1.532 μm fiber laser, using intracavity etalons to generate single longitudinal mode operation. We obtained 0.749 W single longitudinal mode output power at 1.645 μm from an Er:YAG laser with two intracavity etalons. The M²-factors of the Er:YAG laser were 1.041 and 1.068 in the x and y directions, respectively.     

Large aperture superconducting magnet (benkei)

Benkei, which was a large window frame conventional magnet at KEK has been converted to a superconducting magnet. In the conversion, the pole gap has been doubled from 0.5 m to 1.0 m retaining an analysing power at 2 T m. Several new techniques were applied to coil windings and cryostat fabrication. The superconducting Benkei has shown satisfactory performances for long term operation.     

变截面悬链线箱型无铰拱桥切割爆破拆除

某中承变截面悬链线箱型无铰拱桥,因部分已出现裂缝和公路建设的需要,必须拆除。通过试验研究,并根据桥以钢结构为主的特点,采用TNT/PENT(40/60)的聚能药包对钢结构实施爆破切割。文中介绍了爆破方案的选择、预处理和切割爆破的设计、起爆网路以及安全技术措施。此外还介绍了自行设计的聚能切割器及其在钢结构上的固定方法。     

14层办公楼定向爆破拆除

待爆破拆除的14层办公楼为框架结构,南北长29m、东西宽19m,最高处为46.2m,总建筑面积6000m~2。施工过程中采用支撑轴前移的方法,有效地控制了楼体后坐。由于设计了合理的爆破参数,采取了有效的安全防护措施,使爆破拆除达到了预期效果。     

Wide-angle emission and single-mode deformed circular microlasers with a flat side

We demonstrate wide-angle emission and single mode operation in deformed circular microlasers with a flat side. The mode characteristics of a metallic confined deformed circular resonator with a flat side are investigated by finite-difference time-domain simulation. The numerical results indicate that this structure is suitable to realize wide-angle emission. Furthermore, metallic confined deformed circular microlasers with a flat side are fabricated using common photolithography and inductively coupled-plasma etching techniques. A continuous-wave single-mode operation with a side mode suppression ratio of 25 dB is achieved at an injection current of 4 mA for an 8 μm radius microlaser with a flat side. Additionally, wide angle emission over 120° is observed from the far-field pattern.     

Self-mode-locking effects in heavily doped single-clad Tm3+-doped silica fibre lasers

Self-mode-locking in single-clad Tm-doped silica fibre lasers operating at 1.92?µm is reported with 100% modulated mode-locked pulses observed for longer fibre lengths up to 6?m. The self-mode-locking was accompanied by self Q-switching. A mode-locked pulse duration of 191?ps has been measured using an autocorrelator based on a two-photon absorption detector for operation at 2?µm assembled for the purpose of this experiment. The experimental pulse train characteristics are found to be consistent with mode-locking theoretical analysis. The origin and properties of self-mode-locking in heavily Tm-doped fibre lasers are discussed.     

Design and operation of a very large ring laser gyroscope

The design and initial operation of a vertical square He-Ne ring laser G0 with a perimeter of 14 m is discussed. This builds on earlier demonstrations of the feasibility of large ring lasers (perimeter approximately 4 m) for single-mode gyroscope operation and with lesser pulling than navigation gyroscopes. With servoing of the rf excitation to yield single-mode operation, G0 gave a quality factor 1 x 10(12) and a Sagnac line with a frequency of 287.8 +/- 1.0 Hz induced by Earth rotation Omega(E). This has confirmed some vital questions over the feasibility of very large gyroscopes for geodetic measurements at the level of 10(-9) Omega(E).     

深孔爆破对电视台卫星发射装置的影响

某地在距电视台卫星发射装置20 m范围内进行深孔爆破,为了保证电视台发射装置安全运行进行全程安全监测.作者根据监测资料对发射装置安全控制标准及快速控制单响药量的方法进行了探讨.介绍了试验方法及成果,提出的成果经验证是安全可行的.     

Accuracy of Doppler Ultrasonography in Measuring Radial Artery Wall Thickness in Hemodialysis Patients: Comparison with Histologic Examination

Increased radial artery wall thickness (RAWT) is considered to be associated with early failure of radiocephalic arteriovenous fistula (AVF) as well as coronary artery atherosclerosis in hemodialysis patients. Therefore, exact measurement of RAWT by noninvasive method before the operation is very important.
Objective:  This study was designed to evaluate accuracy of Doppler ultrasonography in measuring RAWT in hemodialysis patients.
Methods:  This study enrolled 21 hemodialysis patients undergoing radiocephalic AVF operation for the first time. We measured RAWT (intima-media thickness) using high-resolution Doppler ultrasonography at the wrist before the AVF operation. We obtained specimens of the radial artery during the AVF operation and then measured RAWT by histologic examination.
Results:  Mean age of the patients was 60 ± 13 years and the number of females was 7 (33.3%). Mean values of RAWT measured by Doppler ultrasonography and histologic examination were 485 ± 93 μm (300–700 μm) and 426 ± 106 μm (300–700 μm), respectively. The value of RAWT of Doppler sonographic measurement well correlated with that of histologic measurement (r = 0.800, p < 0.001).
Conclusion:  Our data suggest that Doppler ultrasonography is an effective tool in measuring RAWT in hemodialysis patients before AVF operation.     

Quasi-static RAM design for high performance operation at liquid nitrogen temperature

The leakage currents which cause information loss in dynamic random access memories (DRAMs) at room temperature disappear at liquid nitrogen temperature, permitting operation of the circuits without the need for refresh (quasi-static operation). The current drive characteristics of the MOS transistor also improve significantly at liquid nitrogen temperatures. Combining these factors leads to an exploration of high speed dynamic RAM design based upon cells with non-destructive readout. This paper describes an experimental high speed RAM based upon a new two-transistor (2T) memory cell designed to exploit the unique advantages of operation at low temperature. Non-destructive readout coupled with a large d.c. sensible output current yields a high speed RAM with low power consumption. An experimental 4 kbit memory, fabricated using a 2 μm CMOS technology, exhibits an access time of 7 nS at 77 K.     

Power handling capability of water cooled cw linac structures

To determine the ultimate cw power handling capability of room temperature linac structures under different cooling conditions, a prototype 2450 MHz on-axis coupled linac structure has been operated at power levels up to 210 kW/m corresponding to an average energy gradient of 3.5 MeV/m. Mechanical behaviour and changes in the rf parameters during high power operation are described and compared with results from computer modeling of thermal stresses.     

深部开采单孔爆破漏斗实验

针对会泽铅锌矿因浅部资源日益枯竭,逐步向深部开采需要获得准确爆破参数的情况,根据利文斯顿爆破漏斗理论,在会泽铅锌矿深部巷道进行了一系列单孔爆破漏斗实验,得到了爆破漏斗临界埋深为1.21m,最佳埋深为0.6m,最佳爆破漏斗体积为0.153m~3,最佳埋深比为0.495 9,应变能系数为1.807 5m/kg~(1/3)等技术参数。爆破漏斗实验是爆破设计和施工的重要技术手段,是获取岩体爆破准确参数的有效途径,其实验结果为会泽铅锌矿深部开采提供了有效的技术支撑。     

A versatile digital signal annunciator for monitor/control panelinstrumentation

An application-specific integrated circuit (ASIC) design for a four-signal annunciator chip is developed. The design incorporates the ability to select three modes of operation of the sound alarm, economic lamp logic for visual indication, an all-digital built-in widely adjustable delay network for the sound alarm, operator acknowledge, autoacknowledge, two separate tones for the sound alarm-one to identify signal detection and the other to identify signal clearance-and logic circuits for cascading any number of chips and robust glitch-free operation. A 3-μm CMOS standard-cell-based layout design in Caltech Intermediate Four (CIF) is obtained. The core area and chip area are 6050 μm×4904 μm and 7426 μm×6188 μm, respectively, and the gate complexity is equivalent to 1537 in two-input NAND gates. Fan-out delay is 34.40 ns, and the estimated power dissipation is ≈11 mW     

Reflectometric frequency-modulation continuous-wave distributed fiber-optic stress sensor with forward coupled beams

A distributed optical-fiber stress sensor whose principle of operation is based on the frequency-modulation continuous-wave technique is reported. The sensor consists of a length of birefringent fiber with a mirror attached to one end, a diode laser, and a p-i-n photodiode detector. The intensity and the location of an applied stress are determined simultaneously by detecting the amplitude and the frequency of the beat signal, which is produced by two forward-coupled mode beams. The system was found to have a reasonable spatial resolution of 0.85 m (rms error) in a sensing range of 100 m. The advantages and limitations of the sensor are also discussed.     

Growth of large ultratransparent KCl single crystals

This paper reports the successful realization and operation of an installation for growing single crystals of ultratransparent KCl by injecting the reactive atmosphere. The devised procedure and apparatus can be used for preparing on a reproducible basis large-single-crystalline ingots with bulk absorption at 10.6 μm approaching the intrinsic limit, as requested in high power laser applications.     

林德50000m~3/h快速变负荷空分装置

林德公司一套 5 0 0 0 0± 1 2 0 0 0m3/h空分装置 ,2 0 0 2年 5月在奥地利林茨钢厂投运。介绍了此快速变负荷空分装置的产品参数、工艺流程、单体设备以及灌入液氧或液氮、快速变负荷1 2 0 0 0m3/h的运行情况     

空气设备氩馏分流量影响因素及调节方法分析

空分设备下塔、上塔、粗氩塔的不同精馏工况影响氩馏分流量的因素不同,使得氩馏分流量的调节方法也不同。以马钢20000 m 3/h液氧内压缩流程空分设备与35000 m 3/h氧气外压缩流程空分设备为例,详细分析空分设备下塔、上塔、粗氩塔不同精馏工况对氩馏分流量的不同影响因素,介绍20000 m 3/h空分设备热开车粗氩塔投运阶段、35000 m 3/h空分设备正常运行变负荷状态的氩馏分流量调节方法运用实例。