A novel definition of the times-diffraction-limit (TDL) number of a laser beam is given. A comparison is made with the commonly used beam-propagation parameter M2, which is unreliable for hard-edge beams, like those produced by unstable resonators with diffraction output coupling. The new suggested TDL number definition doesn't rely on the real beam comparison to a Gaussian beam, but on the comparison of the far-field performances of the real beam with respect to those of a uniphase beam with the same amplitude profile in the near field. A practical method is also given for the estimation of the TDL number of real beams. Finally, this procedure is applied to the high-peak-power laser beams generated by two excimer laser systems developed in ENEA.
{"title":"Definition and measurement of the times-diffraction-limit number of high-power laser beams","authors":"S. Bollanti, P. Di Lazzaro, D. Murra","doi":"10.1117/12.316570","DOIUrl":"https://doi.org/10.1117/12.316570","url":null,"abstract":"A novel definition of the times-diffraction-limit (TDL) number of a laser beam is given. A comparison is made with the commonly used beam-propagation parameter M2, which is unreliable for hard-edge beams, like those produced by unstable resonators with diffraction output coupling. The new suggested TDL number definition doesn't rely on the real beam comparison to a Gaussian beam, but on the comparison of the far-field performances of the real beam with respect to those of a uniphase beam with the same amplitude profile in the near field. A practical method is also given for the estimation of the TDL number of real beams. Finally, this procedure is applied to the high-peak-power laser beams generated by two excimer laser systems developed in ENEA.","PeriodicalId":373160,"journal":{"name":"GR-I International Conference on New Laser Technologies and Applications","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133830863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Long-wavelength vertical-cavity surface-emitting semiconductor lasers are investigated and heating effects on the light vs. current characteristics of VCSELs are analyzed by thermal-electric, optical, and electronic modeling. The model includes nonuniform current injection, carrier diffusion, stimulated emission, distributed heat sources, and active material band structure calculations. Device parameters such as threshold current, and external quantum efficiency are evaluated. Simulated power vs. current characteristics exhibit the typical thermal roll-over in continuous wave operation. The model is applied to two specific optimized underetched structure designs in order to provide an understanding of the current-funneling mechanism and the thermal limitations of such devices.
{"title":"Numerical modeling of long-wavelength vertical-cavity surface-emitting semiconductor lasers. I. Continuous-wave modeling","authors":"A. Tsigopoulos, V. Paschos, P. Salet, J. Jacquet","doi":"10.1117/12.316558","DOIUrl":"https://doi.org/10.1117/12.316558","url":null,"abstract":"Long-wavelength vertical-cavity surface-emitting semiconductor lasers are investigated and heating effects on the light vs. current characteristics of VCSELs are analyzed by thermal-electric, optical, and electronic modeling. The model includes nonuniform current injection, carrier diffusion, stimulated emission, distributed heat sources, and active material band structure calculations. Device parameters such as threshold current, and external quantum efficiency are evaluated. Simulated power vs. current characteristics exhibit the typical thermal roll-over in continuous wave operation. The model is applied to two specific optimized underetched structure designs in order to provide an understanding of the current-funneling mechanism and the thermal limitations of such devices.","PeriodicalId":373160,"journal":{"name":"GR-I International Conference on New Laser Technologies and Applications","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129032780","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Experimental results are presented concerning the application of laser-induced breakdown spectroscopy (LIBS) for the detection of metals in plastics and biological tissues. LIBS has been used for the detection and the determination of the concentration of antimony in plastic and manganese in human hairs respectively. Calibration curves are presented for the above metals and the limiting factors of the technique are discussed.
{"title":"Laser-induced breakdown spectroscopy (LIBS): a tool for rapid in-situ elemental analysis","authors":"S. Couris, A. Mavromanolakis, C. Fotakis","doi":"10.1117/12.316588","DOIUrl":"https://doi.org/10.1117/12.316588","url":null,"abstract":"Experimental results are presented concerning the application of laser-induced breakdown spectroscopy (LIBS) for the detection of metals in plastics and biological tissues. LIBS has been used for the detection and the determination of the concentration of antimony in plastic and manganese in human hairs respectively. Calibration curves are presented for the above metals and the limiting factors of the technique are discussed.","PeriodicalId":373160,"journal":{"name":"GR-I International Conference on New Laser Technologies and Applications","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134271363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Industrial manufacturers produce many types of pressure gauges and transducers according to the applications, for gas or liquid, for high-medium and low pressure ranges. Nowadays the current production technology generally prefers to weld by micro TIG source the metallic corrugated membranes to the gauge or transducer bodies for the products, operating on the low pressure or medium pressure ranges. For the other ones, operating to high pressure range, generally the two components of the transducers are both threaded only and threaded and then circularly welded by micro TIG for the other higher range, till to 1000 bar. In this work the products, operating on the approximately equals 30 divided by 200 bar, are considered. These, when assembled on industrial plants, as an outcome of a non-correct operating sequence, give a 'shifted' electrical signal. This is due to a shift of the 'zero electrical signal' that unbalances the electrical bridge - thin layer sensor - that is the sensitive part of the product. Moreover, for the same problem, often some mechanical settlings of the transducer happen during the first pressure semi-components, with an increasing of the product manufacturing costs. In light of all this, the above referred, in this work the whole transducer has been re-designed according to the specific laser welding technology requirements. On the new product no threaded parts exist but only a circular laser welding with a full penetration depth about 2.5 divided by 3 mm high. Three different alloys have been tested according to the applications and the mechanical properties requested to the transducer. By using a 1.5 KW CO2 laser system many different working parameters have been evaluated for correlating laser parameters to the penetration depths, crown wides, interaction laser-materia times, mechanical and metallurgical properties. Moreover during the laser welding process the measurements of the maximum temperature, reached by the transducer top, has been read and recorded. At least some transducers, before the usual destructive testings, have been undertaken to many pressure test cycles to verify any pressure drops, the transducer sealing and the total quality of the new product.
{"title":"Medium- and high-pressure gauges and transducers produced by laser welding technology","authors":"G. Daurelio, F. Nenci, M. Cinquepalmi, G. Chita","doi":"10.1117/12.316610","DOIUrl":"https://doi.org/10.1117/12.316610","url":null,"abstract":"Industrial manufacturers produce many types of pressure gauges and transducers according to the applications, for gas or liquid, for high-medium and low pressure ranges. Nowadays the current production technology generally prefers to weld by micro TIG source the metallic corrugated membranes to the gauge or transducer bodies for the products, operating on the low pressure or medium pressure ranges. For the other ones, operating to high pressure range, generally the two components of the transducers are both threaded only and threaded and then circularly welded by micro TIG for the other higher range, till to 1000 bar. In this work the products, operating on the approximately equals 30 divided by 200 bar, are considered. These, when assembled on industrial plants, as an outcome of a non-correct operating sequence, give a 'shifted' electrical signal. This is due to a shift of the 'zero electrical signal' that unbalances the electrical bridge - thin layer sensor - that is the sensitive part of the product. Moreover, for the same problem, often some mechanical settlings of the transducer happen during the first pressure semi-components, with an increasing of the product manufacturing costs. In light of all this, the above referred, in this work the whole transducer has been re-designed according to the specific laser welding technology requirements. On the new product no threaded parts exist but only a circular laser welding with a full penetration depth about 2.5 divided by 3 mm high. Three different alloys have been tested according to the applications and the mechanical properties requested to the transducer. By using a 1.5 KW CO2 laser system many different working parameters have been evaluated for correlating laser parameters to the penetration depths, crown wides, interaction laser-materia times, mechanical and metallurgical properties. Moreover during the laser welding process the measurements of the maximum temperature, reached by the transducer top, has been read and recorded. At least some transducers, before the usual destructive testings, have been undertaken to many pressure test cycles to verify any pressure drops, the transducer sealing and the total quality of the new product.","PeriodicalId":373160,"journal":{"name":"GR-I International Conference on New Laser Technologies and Applications","volume":"88 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129652341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Persephonis, V. Giannetas, C. Georgiades, J. Parthenios, A. Ioannou
The resistance and inductance of a laser discharge in a pulsed gas laser are considered theoretically in this paper. The total charge and the dimensions of the discharge volume are responsible for the resistance and inductance of the laser channel respectively. Generally, the inductance increases either decreasing electrode length or discharge thickness, or increasing the interelectrode distance. The direct dependence of the resistance and inductance with the microscopically plasma parameters, total charge and drift velocity, was discovered in this paper through the external driving circuit and especially through its capacitance. The values of the capacitors form the total charge while the coupling of the capacitors in the circuits forms the drift velocity. These are inferred dealing with the two most common circuits used in a pulsed gas laser, namely the doubling circuit and the charge transfer circuit for all possible combinations of capacitance allocation.
{"title":"Electrical characteristics of the discharge in a pulsed gas laser","authors":"P. Persephonis, V. Giannetas, C. Georgiades, J. Parthenios, A. Ioannou","doi":"10.1117/12.316555","DOIUrl":"https://doi.org/10.1117/12.316555","url":null,"abstract":"The resistance and inductance of a laser discharge in a pulsed gas laser are considered theoretically in this paper. The total charge and the dimensions of the discharge volume are responsible for the resistance and inductance of the laser channel respectively. Generally, the inductance increases either decreasing electrode length or discharge thickness, or increasing the interelectrode distance. The direct dependence of the resistance and inductance with the microscopically plasma parameters, total charge and drift velocity, was discovered in this paper through the external driving circuit and especially through its capacitance. The values of the capacitors form the total charge while the coupling of the capacitors in the circuits forms the drift velocity. These are inferred dealing with the two most common circuits used in a pulsed gas laser, namely the doubling circuit and the charge transfer circuit for all possible combinations of capacitance allocation.","PeriodicalId":373160,"journal":{"name":"GR-I International Conference on New Laser Technologies and Applications","volume":"3423 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129034044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I. Apostol, R. Stoian, C. Luculescu, R. Dabu, A. Stratan, S. Udrea, Catalin Flacau
We report a YBa2Cu3O7 PLD method designed to reduce the oxygen deficiency in the as deposited YBCO superconducting thin films.OPtical dissociation of O2 buffer gas in front of the plume using a second IR laser pulse simultaneously with the UV laser beam producing the ablation plasma is proposed as a method for oxidation enhancement and oxygen enrichment in the deposited film. Oxides enhancement measurements were performed by optical spectroscopy on YO, BaO and CuO lines at large distances from the target surface. Temporal evolution of ionic, neutral and oxide lines was analyzed in 400-620 nm region, in correlation with plasma expansion in the ambient gas.
{"title":"Laser ablation of YBCO targets and optical-breakdown-assisted PLD for high Tc superconducting thin films deposition","authors":"I. Apostol, R. Stoian, C. Luculescu, R. Dabu, A. Stratan, S. Udrea, Catalin Flacau","doi":"10.1117/12.316620","DOIUrl":"https://doi.org/10.1117/12.316620","url":null,"abstract":"We report a YBa2Cu3O7 PLD method designed to reduce the oxygen deficiency in the as deposited YBCO superconducting thin films.OPtical dissociation of O2 buffer gas in front of the plume using a second IR laser pulse simultaneously with the UV laser beam producing the ablation plasma is proposed as a method for oxidation enhancement and oxygen enrichment in the deposited film. Oxides enhancement measurements were performed by optical spectroscopy on YO, BaO and CuO lines at large distances from the target surface. Temporal evolution of ionic, neutral and oxide lines was analyzed in 400-620 nm region, in correlation with plasma expansion in the ambient gas.","PeriodicalId":373160,"journal":{"name":"GR-I International Conference on New Laser Technologies and Applications","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116089805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The nonlinear optical response of fullerene solutions is examined as a function of the incident radiation pulse duration and intensity. Using the z-scan technique, the nonlinear absorption and the nonlinear refraction are studied for 10 nsec, 532 nm and 0.5 psec, 497 nm laser pulses. The corresponding nonlinear parameters are determined and their intensity dependence is shown to be the indicative parameter for the understanding of the origin of the observed nonlinearity. Possible applications of the nonlinear optical properties of fullerenes in optoelectronics are proposed.
{"title":"Optical nonlinearities of fullerenes and their implications in optoelectronics","authors":"E. Koudoumas, S. Couris","doi":"10.1117/12.316578","DOIUrl":"https://doi.org/10.1117/12.316578","url":null,"abstract":"The nonlinear optical response of fullerene solutions is examined as a function of the incident radiation pulse duration and intensity. Using the z-scan technique, the nonlinear absorption and the nonlinear refraction are studied for 10 nsec, 532 nm and 0.5 psec, 497 nm laser pulses. The corresponding nonlinear parameters are determined and their intensity dependence is shown to be the indicative parameter for the understanding of the origin of the observed nonlinearity. Possible applications of the nonlinear optical properties of fullerenes in optoelectronics are proposed.","PeriodicalId":373160,"journal":{"name":"GR-I International Conference on New Laser Technologies and Applications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131089629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Jendrzejewski, G. Rabczuk, R. Zaremba, G. Śliwiński
3D-structures obtained by means of laser cladding of the metal alloy powders: bronze B10 and stellite 6 and the process parameters are studied experimentally. The structures are made trace-on-trace by remelting of the metal powder injected into the focusing region of the 1.2 kW CO2 laser beam. For the powder and sample feeding rates of 8-22 g/min and 0.4-1.2 m/min, respectively, and the applied beam intensities not exceeding 2 X 105 W cm-2 the process is stable and regular traces connected via fusion zones are produced for each material. The thickness of these zones does not exceed several per cent of the layer height. The process results in the efficient formation of multilayer structures. From their geometry the effect of energy coupling and interaction parameters are deduced. Moreover, the microanalysis by means of SEM- and optical photographs of samples produced under different experimental conditions confirms the expected mechanical properties, low porosity and highly homogenous structure of the multilayers. In addition to the known material stellite 6 the bronze B10 is originally proposed for a rapid prototyping.
对铜B10和钨铬钴合金粉末激光熔覆获得的三维结构及其工艺参数进行了实验研究。通过将金属粉末注入到1.2 kW CO2激光束的聚焦区域中进行重熔，制备出痕量对痕量的结构。当粉末和样品的进料速率分别为8- 22g /min和0.4-1.2 m/min，施加的光束强度不超过2 X 105w cm-2时，该过程是稳定的，并且每种材料都产生了通过熔合区连接的规则痕迹。这些带的厚度不超过层高的百分之几。该过程导致多层结构的有效形成。从它们的几何形状出发，推导了能量耦合和相互作用参数的影响。此外，通过不同实验条件下样品的SEM和光学照片进行微观分析，证实了多层材料的预期力学性能、低孔隙率和高度均匀的结构。除了已知材料钨铬钴合金6外，青铜B10最初被提议用于快速原型设计。
{"title":"Laser stereolithography by multilayer cladding of metal powders","authors":"R. Jendrzejewski, G. Rabczuk, R. Zaremba, G. Śliwiński","doi":"10.1117/12.316613","DOIUrl":"https://doi.org/10.1117/12.316613","url":null,"abstract":"3D-structures obtained by means of laser cladding of the metal alloy powders: bronze B10 and stellite 6 and the process parameters are studied experimentally. The structures are made trace-on-trace by remelting of the metal powder injected into the focusing region of the 1.2 kW CO2 laser beam. For the powder and sample feeding rates of 8-22 g/min and 0.4-1.2 m/min, respectively, and the applied beam intensities not exceeding 2 X 105 W cm-2 the process is stable and regular traces connected via fusion zones are produced for each material. The thickness of these zones does not exceed several per cent of the layer height. The process results in the efficient formation of multilayer structures. From their geometry the effect of energy coupling and interaction parameters are deduced. Moreover, the microanalysis by means of SEM- and optical photographs of samples produced under different experimental conditions confirms the expected mechanical properties, low porosity and highly homogenous structure of the multilayers. In addition to the known material stellite 6 the bronze B10 is originally proposed for a rapid prototyping.","PeriodicalId":373160,"journal":{"name":"GR-I International Conference on New Laser Technologies and Applications","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131025244","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The stimulated Raman scattering (SRS) technique has been sued for upward and downward shifting the 3rd harmonic of a pulsed Nd:YAG laser into the 274-503 nm wavelength region. The gases investigated were hydrogen (H2) and deuterium (D2), using helium (He) as buffer gas. Experimental results on the output Stokes and anti-Stokes conversion efficiencies of the forward SRS technique in H2, D2 and He, versus Raman gas pressure and input pump energy, are presented. Conversion efficiencies more than 40 percent were achieved and the output energies obtained at the various ultraviolet and visible wavelengths were of the order of several mJ.
{"title":"Stimulated Raman scattering in H2 and D2 using a pulsed Nd:YAG laser at 355 nm","authors":"A. Papayannis, G. Tsikrikas, A. Serafetinides","doi":"10.1117/12.316579","DOIUrl":"https://doi.org/10.1117/12.316579","url":null,"abstract":"The stimulated Raman scattering (SRS) technique has been sued for upward and downward shifting the 3rd harmonic of a pulsed Nd:YAG laser into the 274-503 nm wavelength region. The gases investigated were hydrogen (H2) and deuterium (D2), using helium (He) as buffer gas. Experimental results on the output Stokes and anti-Stokes conversion efficiencies of the forward SRS technique in H2, D2 and He, versus Raman gas pressure and input pump energy, are presented. Conversion efficiencies more than 40 percent were achieved and the output energies obtained at the various ultraviolet and visible wavelengths were of the order of several mJ.","PeriodicalId":373160,"journal":{"name":"GR-I International Conference on New Laser Technologies and Applications","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123739858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Laser techniques for local particle velocity and size measurements in flows are presented and discussed. The laser doppler anemometer utilizing the Doppler shift of light scattered on small particles in a flow for velocity measurements is the basis of the presented techniques. Furthermore phase Doppler anemometry based on the spatial properties of the Doppler shift and shadow Doppler velocimetry utilizing the shadow image of particle for size measurements are briefly discussed. Experimental results illustrating the use of the techniques are presented. These comprise particle velocity measurements in a sudden expansion liquid solid flow as well as in a model of a beater wheel mill. PDA measurements of the size distribution of droplets produced by a nebulizer ar also presented.
{"title":"Recent developments in nonintrusive measuring techniques for particle velocity and size measurements","authors":"T. Achimastos, M. Founti, T. Panidis","doi":"10.1117/12.316600","DOIUrl":"https://doi.org/10.1117/12.316600","url":null,"abstract":"Laser techniques for local particle velocity and size measurements in flows are presented and discussed. The laser doppler anemometer utilizing the Doppler shift of light scattered on small particles in a flow for velocity measurements is the basis of the presented techniques. Furthermore phase Doppler anemometry based on the spatial properties of the Doppler shift and shadow Doppler velocimetry utilizing the shadow image of particle for size measurements are briefly discussed. Experimental results illustrating the use of the techniques are presented. These comprise particle velocity measurements in a sudden expansion liquid solid flow as well as in a model of a beater wheel mill. PDA measurements of the size distribution of droplets produced by a nebulizer ar also presented.","PeriodicalId":373160,"journal":{"name":"GR-I International Conference on New Laser Technologies and Applications","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115226916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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