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The surrounding environment of overhead transmission lines is complex and changeable, which often causes short circuit trip because of the foreign objects such as kite, colored ribbon and plastic film. It brings serious threat to the security of power grid and causes great economic loss. In this paper, an advanced laser distance removing method is proposed in this paper, which can quickly and reliably remove the foreign objects on the line. In this paper, the principle analysis of overhead line laser removal is carried out, and the comparison test results with different lasers of different kinds of lasers are carried out, and the optimal selection scheme of laser is obtained. Laser aiming technology, cooling technology and safety guarantee measures are developed. It has high application value for removing obstacles from overhead lines. [ABSTRACT FROM AUTHOR]

This paper is involved in a test of performance comparison of multifunctional high-speed highway condition monitors. Data of rut, IRI and cracking has been collected and analysis of variation coefficient and correlation has also been analyzed. A significant difference of all samples is revealed in the test. It is of great affection for operators, work condition to the result of the test. And a few of the samples even didn't finish some sections of the test. Above all, the result of the test can provide the department of maintenance very important information. [ABSTRACT FROM AUTHOR]

Acceleration of particles in laser-driven dielectric structures fabricated using semiconductor manufacturing techniques is a new and promising approach to developing future generations of ultra-compact particle accelerators. We present a conceptual layout for a wafer scale device based on this approach. We examine one particularly promising near-term use for such accelerators in radiation oncology, and discuss energy scaling for high energy physics and basic energy science applications. [ABSTRACT FROM AUTHOR]

Dynamic torque calibration method based on rotating table and interferometric system is studied in this paper. A load mass with certain moment of inertia are screwed on the top of torque transducer, the dynamic torque is realized by load object are traceable to angular acceleration and moment of inertia of the object by M(t) = IӪ(t), where I is the total moment of inertia acting on the sensing element of the torque transducer and Ӫ is the time and spatial-dependent angular acceleration of the load object which is directly measured by a laser interferometer. This paper will introduce a dynamic torque calibration system developed at Changcheng Institute of Metrology and Measurement (CIMM). It uses servomotor to generate dynamic torque in the range from 0.1Nm to 200Nm, and heterodyne laser interferometers cooperated with column grating are used for angular acceleration measurement. An airbearing system is developed to increase the performance of the dynamic turque calibration system. This paper introduce the setup of the dynamic torque calibration system. [ABSTRACT FROM AUTHOR]

The Polypropylene is one of the most versatile polymer materials used in the industry. Due to this versatility, it is possible to use it in different products. This material can also be mixed with several additives namely glass fiber, carbon nanotubes, etc. This compatibility with different additives allows also obtaining products with characteristics that goes from an impact absorber to an electricity conductor. When is necessary to join components in PP they could be welded through hot plate, ultrasonic weld and also by laser. This study had the objective of study the influence of several variables, capable of influence the final quality of the seam. In this case were studied variables of the injection molding process as mold temperature and cooling time. Was also studied laser welding variables and different materials. The results showed that the variables that have the most influence were mould temperature, laser velocity and laser diameter. The seams were analyzed using Optical Microscopy technique. The seams showed perfect contact between the materials analyzed, despite the high standard variation presented in the mechanical testes. [ABSTRACT FROM AUTHOR]

Compared to different welding methods such as ultrasonic welding, laser transmission welding is a relatively new technology to join thermoplastic parts. The most significant advantages over other methods are the contactless energy input which can be controlled very precisely and the low mechanical loads on the welded parts. Therefore, laser transmission welding is used in various areas of application, for example in medical technology or for assembling headlights in the automotive sector. However, there are several challenges in welding dissimilar thermoplastics. This may be due to different melting points on the one hand and different polarities on the other hand. So far these problems are faced with the intermediate layer technique. In this process a layer bonding together the two components is placed between the components. This means that an additional step in the production is needed to apply the extra layer. To avoid this additional step, different ways of joining dissimilar thermoplastics are investigated. In this regard, the improvement in the weldability of the dissimilar thermoplastics polyamide 6 (PA 6) and polypropylene (PP) by means of plasma surface modification and contour welding is examined. To evaluate the influence of the plasma surface modification process on the subsequent welding process of the two dissimilar materials, the treatment time as well as the storage time between treatment and welding are varied. The treatment time in pulsed micro wave excited oxygen plasmas with an electron density of about 1x1017 m-3 is varied from 0.5 s to 120 s and the time between treatment and welding is varied from a few minutes up to a week. As reference, parts being made of the same polymer (PP and PA 6) are welded and tested. For the evaluation of the results of the welding experiments, short-time tensile tests are used to determine the bond strength. Without plasma treatment the described combination of PA 6/PP cannot be welded with sufficient bond strength to withstand handling of the samples. In contrast, the tear-out force of previously plasma treated samples can be determined to up to 1400 N. The achieved bond strengths are higher than of untreated PP/PP welded parts (about 1000 N). [ABSTRACT FROM AUTHOR]

Laser cutting is a thermal separation process widely used in shaping and contour cutting applications. It is a very fast and at the same time very accurate technology with the optical tool laser not being exposed to any wear. There are, however, gaps in understanding the dynamics of the process, especially with regard to issues related to cut quality. Numerical modeling and simulation of the laser cutting process has shown to improve that understanding without the need for executing a lot of experiments in the real world. In this paper, the utility of a metamodeling technique in gaining valuable information relating to the optimization of a laser cutting process, where a CW laser is used to cut, is analyzed. The numerical simulation itself is characterized by a high dimensional input parameter set. Each parameter has its own range, and thus they are together forming the parameter domain space. The quality criteria, which are predicted with the numerical model, are analyzed together with the parameter domain space and are thus used to optimize the process. However, simulation results can only help in the build-up of process understanding, if they can be presented in their entirety and together with their origin in the parameter domain. For this purpose a new metamodeling concept is presented, which takes the results from numerical simulations and generates a process map, clearly indicating the process domains. [ABSTRACT FROM AUTHOR]

To date, differing implementations of continuous scan laser Doppler vibrometry have been demonstrated by various academic institutions, but since the scan paths were defined using step or sine functions from function generators, the paths were typically limited to 1D line scans or 2D areas such as raster paths or Lissajous trajectories. The excitation was previously often limited to a single frequency due to the specific signal processing performed to convert the scan data into an ODS. In this paper, a configuration of continuous-scan laser Doppler vibrometry is demonstrated which permits scanning of arbitrary areas, with the benefit of allowing multi-frequency/broadband excitation. Various means of generating scan paths to inspect arbitrary areas are discussed and demonstrated. Further, full 3D vibration capture is demonstrated by the addition of a range-finding facility to the described configuration, and iteratively relocating a single scanning laser head. Here, the range-finding facility was provided by a Microsoft Kinect, an inexpensive piece of consumer electronics. [ABSTRACT FROM AUTHOR]

To Assemble a complete subsystem as a rear lamp, is necessary to have different machines and to perform several tasks. This necessity obliges the companies to have large structures to support all the assembling process. These huge structures are very costly and have as a consequence the reduction of the competitiveness of the companies. The process presented in this document has the intention of reducing the number of tasks needed to produce the final subsystem/product. To achieve this goal were combined several technologies, as in-mould assembling, laser welding and LEDs (light-emitting diode). One of the advantages of this process was the utilization of only one injection molding machine with three injection units to do all the assembling process. To achieve the main objective, firstly, the rear lamp was designed according to with the legislation of UNECE Vehicle Regulations - 1958 Agreements; Regulation No. 50 -Rev.2 - Position lamps, stop lamps, direction indicators for motorcycles. Posterior several polymeric materials were studied at different levels. Initial were studied several concentrations of carbon nanotubes mixed with PC (polycarbonate). This had the objective of determine, if these materials are suitable to conduct the necessary electric current to turn on the different LEDs. One of the main advantages of this process is the use of the laser transmission welded process. Since, with this welding technology is possible reduce the complexity of the final part. To understand the potentialities of this technology a combination of two materials was studied. The studied showed that all materials presented a high transparency to the laser beam. In terms of weld process, the study showed that the best welding conditions are the lowest velocity, diameter and power. With these studies was possible conclude that this new process is suitable to be implemented at the industrial level. [ABSTRACT FROM AUTHOR]

In this paper we outline the main quantum properties of the system of nano-based laser called Dipole Nano-Laser emphasizing mainly on its ability to produce coherent light and for different configurations such as different embedding materials and subjecting it to an external classical electric field. [ABSTRACT FROM AUTHOR]

The formation and growth of Fe based aluminum diffusion layers at the Fe-Al interface have been investigated to improve the surface hardness. The diffusion of Fe into Al has been accomplished by focusing a Q-switched Nd:YAG laser on the modified surface. The variety of the layer depth is achieved based on the type of heating and quenching media. Microstructural characterization and mechanical properties of the modified surface were carried out via gas discharge spectrometer GDS, X-Ray diffraction (XRD), Scanning electron microscope (SEM), and Vickers Hardness tester. The results indicate that hardness at the interface of Fe-Al layer is increased. The optimum hardness achieved as 93 HV at corresponding critical energy density of 438 Jcm-2. [ABSTRACT FROM AUTHOR]

Experiments using a laser-accelerated flyer impact system were conducted on various forms of nickel-aluminum over a range of velocities in attempt to characterize the processes leading to reaction initiation and product formation. The laser-accelerated flyer system consists of an Nd:YAG, 3-Joule, 1064-nm seeded laser, beam shaping optics, recovery chamber, and velocity interferometry diagnostics. Using various flyer materials, impact velocities up to 1.4 km/sec have been measured. The laser-accelerated flyer system was used to conduct impact experiments on Ni-Al powder compacts, Ni-Al vapor-deposited foils, and single Ni-Al interface configurations. Subsequently, post-mortem characterization was performed to identify the processes that lead to reaction initiation and products formed in the various Ni-Al configurations. [ABSTRACT FROM AUTHOR]

Hexanitrostilbene (HNS) is a secondary explosive with attractive properties for detonator usage, including thermal stability, good safety properties and easy initiability. It is desirable to characterize the shock initiation of detonator explosives to enable optimization of system parameters. HNS is a suitable explosive for use in electrical and optical slapper detonators, where shock pressures generated by the flyer plates used can exceed 30 GPa. This extreme shock regime can be explored by initiating HNS with a variety of flyer thicknesses, from 3 to 25 microns at velocities of several km/s. Thresholds for optical and electrical slapper detonators were evaluated, and Photonic Doppler Velocimetery used to determine the flyer velocity at threshold. The flyer diameters are in excess of the critical diameter for HNS, allowing a one-dimensional treatment of the initiation. Calculated values for pressure and shock duration are used to evaluate the critical energy criteria P²τ. The James Criterion is used to analyse the initiation, with values of EC and ΣC being determined from experimental data, providing a predictive capability to model other configurations such as different flyer thicknesses and materials. [ABSTRACT FROM AUTHOR]

The unprecedented laser capabilities of the National Ignition Facility (NIF) make it possible for the first time to countenance laboratory-scale experiments in which gigabar pressures can be applied to a reasonable volume of material, and sustained long enough for percent level equation of state measurements to be made. We describe the design for planned experiments at the NIF, using a hohlraum drive to induce a spherically-converging shock in samples of different materials. Convergence effects increase the shock pressure to several gigabars over a radius of over 100 microns. The shock speed and compression will be measured radiographically over a range of pressures using an x-ray streak camera. In some cases, we will use doped layers to allow a radiographic measurement of particle velocity. [ABSTRACT FROM AUTHOR]

This paper discusses the application of a nanosecond laser-shock to induce a cavitation bubble in a suspension of water and aluminum and an underwater ablation event at an aluminum target to generate the conditions under which metal fuels will oxidize with water. The energy deposited into the plasma is varied with laser energy, allowing for a laboratory-scale setting where particle reactivity can be investigated. In the case of suspended aluminum fuel particles, the bubble dynamics (expansion radius and period) are augmented by the presence of the reactive particles. Laser ablation at an aluminum surface is also accompanied by fast oxidation, augmenting the bubble formation. Highspeed framing camera images along with time-resolved emission spectra are used to monitor bubble dynamics and reactivity. The critical conditions necessary to promote underwater reactivity of fuels in this laboratory setting will be used to guide future applications of reactive materials. [ABSTRACT FROM AUTHOR]

We have developed a laser-Compton gamma-ray source at beamline (BL1) in NewSUBARU, an electron storage ring operating at electron energies of 0.7–1.5 GeV. Initially, we generated 17–37 MeV gamma rays using a Nd:YVO4 laser operating at 1.06 μm and 0.53 μm, achieving a luminosity of 6000 photons/(W·mA·s) and a flux of 5×106 photons/s with a laser power of 4 W and a beam current of 200 mA. We then installed a CO2 laser operating at 10.6 μm, and generated gamma rays in the energy range of 1–4 MeV. In this range, the gamma-ray luminosity is 7300 photons/(W·mA·s) and the flux is 5.6×106 photons/s when operating the laser at 4 W and 200 mA. These performances are in good agreement with calculations. We will next add a Tm-fiber laser operating at 2 μm to generate gamma rays in the energy range of 4–21 MeV, using a laser-focusing design to generate the maximum flux. The luminosity of this stage is calculated to be 6400 photons/(W·mA·s). Nd:YVO4, CO2, and Tm-fiber laser are all capable of operating in a high-power regime and can generate kW-level output power. At present, the maximum gamma-ray flux is limited only by the laser power. When operating the laser at 1 kW of output power with a beam current of 200 mA, we expect a flux of up to ∼109 photons/s. At NewSUBARU, up to several dozen MeV gamma-ray sources are capable of generating such high power. [ABSTRACT FROM AUTHOR]

In this paper, a circuit model is devised to analyze nonlinear behaviour of quantum cascade lasers. Such nonlinear behavior influences the light output when the laser is driven by currents comparable to the average (DC) current. The simplified 2-level rate equations are first improved. Next, the circuit model is obtained following the approach for interband lasers. The difference between the circuit models of quantum cascade lasers and interband lasers is pointed out. The circuit model is simpler compared to that obtained from a 3-level model. Unlike a circuit model derived earlier from the 2-level model, the present model can handle both small and large current drives. [ABSTRACT FROM AUTHOR]

In mid-February 1986, Peter Ascher and Daniel Choy performed the first Percutaneous Laser Disc Decompression (PLDD) at the Neurosurgical Department, University of Graz, Graz, Austria. It was planned to deliver 1000 joules with a Nd:YAG laser to a herniated L4-5 disc causing sciatica. At 600 joules the procedure was terminated because the pain was gone. Since then, PLDD has spread all over the world, with procedures being performed in the entire spine except for T1-T4 because these discs do not permit percutaneous access with a needle. The success rate has ranged from 70 to 89%, and the complication rate, chiefly discitis, from 0.3 to 1.0%. When successful, return to normal work averages one week. Long term follow-up to 23 years yields a recurrence rate of 4–5%. [ABSTRACT FROM AUTHOR]

Calibration of vibration transducers requires sinusoidal motion over a wide frequency range with low distortion and low cross-axial motion. Piezoelectric shakers are well suited to generate such motion and are suitable for use with laser interferometric methods at frequencies of 3 kHz and above. An advantage of piezoelectric shakers is the higher achievable accelerations and displacement amplitudes as compared to electro-dynamic (ED) shakers. Typical commercial ED calibration shakers produce maximum accelerations from 100 m/s2 to 500 m/s2. Very large ED shakers may produce somewhat higher accelerations but require large amplifiers and expensive cooling systems to dissipate heat. Due to the limitations in maximum accelerations by ED shakers at frequencies above 5 kHz, the amplitudes of the generated sinusoidal displacement are frequently below the resolution of laser interferometers used in primary calibration methods. This limits the usefulness of ED shakers in interferometric based calibrations at higher frequencies. Small piezoelectric shakers provide much higher acceleration and displacement amplitudes for frequencies above 5 kHz, making these shakers very useful for accelerometer calibrations employing laser interferometric measurements, as will be shown in this paper. These piezoelectric shakers have been developed and used at NIST for many years for high frequency calibration of accelerometers. This paper documents the construction and performance of a new version of these shakers developed at NIST for the calibration of accelerometers over the range of 3 kHz to 30 kHz and possibly higher. Examples of typical calibration results are also given. [ABSTRACT FROM AUTHOR]